Science.gov

Sample records for nothofagus pumilio bajo

  1. Nutrient cycling in Nothofagus pumilio forests along an altitudinal gradient in Tierra del Fuego, Argentina

    Treesearch

    Jorge L. Frangi; Marcelo D. Barrera; Laura L. Richter; Ariel E. Lugo

    2005-01-01

    Nothofagus pumilio (lenga) forests form monocultures from sea level to timberline in Tierra de Fuego, Argentina. Past studies suggested that the life form change from erect forest to krummholz had advantages to forest function. Aboveground net primary productivity (NPP) and organic matter production per unit leaf area and growing season day were higher in krummholz...

  2. Fine-scale genetic structure of Nothofagus pumilio (lenga) at contrasting elevations of the altitudinal gradient.

    PubMed

    Mathiasen, Paula; Premoli, Andrea C

    2013-03-01

    Montane forests provide the natural framework to test for various ecological settings at distinct elevations as they may affect population demography, which in turn will affect the spatial genetic structure (SGS). We analyzed the fine-scale SGS of Nothofagus pumilio, which dominates mountain areas of Patagonia, in three pairs of sites at contrasting elevations (low- vs. high-elevation). Within a total area of 1 ha fresh leaf tissue from 90 individuals was collected at each of the six studied stands following a spatially explicit sampling design. Population genetic diversity parameters were analyzed for all sampled individuals using five polymorphic isozyme loci, and a subset of 50 individuals per stand were also screened for five microsatellite loci. The SGS was assessed on 50 individuals/stand, using the combined datasets of isozymes and microsatellites. Most low-elevation stands consisted of older individuals with complex age structures and genetically diverse plots. In contrast, high-elevation stands and one post-fire low-elevation population yielded even-aged structures with evidence of growth suppression, and were genetically homogeneous. All stands yielded significant SGS. Similarly to mature stands of the non-sprouter congener Nothofagus dombeyi, multi-age low-altitude N. pumilio yielded significant SGS weakened by competing species of the understory and the formation of seedling banks. Alike the sprouter Nothofagus antarctica, high-altitude stands produced significant SGS as a consequence of occasional seedling establishment reinforced by vegetative spread.

  3. Differential hypogeous sporocarp production from Nothofagus dombeyi and N. pumilio forests in southern Argentina.

    PubMed

    Nouhra, Eduardo R; Urcelay, Carlos; Longo, M Silvana; Fontenla, Sonia

    2012-01-01

    Mycorrhizal fungi that form hypogeous sporocarps are an important component of the temperate forest soil community. In many regions, such as the Nothofagus forest in the Patagonian Andes, this group of fungi has been poorly studied. Here we examined the spring and autumn community composition of "sequestrate fungi", based on sporocarp production in pure forests of Nothofagus dombeyi (evergreen) and N. pumilio (deciduous). We investigated the possible relationships between these communities and environmental factors over 2 y. The rarefaction curves and the minimal richness estimates converged at nearly the same level for each forest type, and the asymptotes suggested that the sampling effort was sufficient to capture most of the hypogeous sporocarp richness in these forest stands. In total 27 species were recovered. Basidiomycota, Ascomycota and Glomeromycota respectively accounted for nine, two and one genera. Species richness of hypogeous sporocarps varied in relation to forest type but not to season (fall and spring), whereas sporocarp biomass varied according to an interaction between season and forest type. Species richness and sporocarp biomass were positively correlated with rainfall and negatively correlated with altitude. In addition sporocarp species richness was positively related to number of trees per transect. We found that two different forest stands, each dominated by different species of Nothofagus, exhibited different hypogeous sporocarp communities.

  4. Halfway encounters: meeting points of colonization routes among the southern beeches Nothofagus pumilio and N. antarctica.

    PubMed

    Soliani, Carolina; Tsuda, Yoshiaki; Bagnoli, Francesca; Gallo, Leonardo A; Vendramin, Giovanni G; Marchelli, Paula

    2015-04-01

    The Patagonian region is characterized by a complex biogeographic history, with evidence of deep phylogeographic breaks shared among species. Of particular interest to conservation is the nature of colonization and settlement patterns after the last glacial period, including the detection of secondary contact between different lineages and/or hybridization among related species around phylogeographic breaks. Here we studied population demography and past hybridization of two widespread tree species endemic to South America, Nothofagus pumilio and N. antarctica. Using 8 nuclear microsatellites we genotyped 41 populations of both species. Genetic variation and structure across the geographic region were evaluated within and among species and the past demographic history of hybridization between the two species was inferred using Approximate Bayesian Computation (ABC). Northern and southern lineages were identified in each species, and Bayesian clustering revealed their convergence at mid latitudes (42°S). Spatial genetic structure (SGS) also indicated the existence of a genetic discontinuity at these latitudes, which is in agreement with previous data from maternal DNA markers. Several populations around 42-44°S presented high levels of genetic diversity with a decrease toward southern populations. Even though the species are clearly differentiated (G'ST=0.335), admixed gene pools were observed in both species. Two independent runs of ABC suggested that inter species admixture-like patterns occurred within the timescale of the Last Glacial Maximum (around 20,000 BP). We also provide evidences of recent and bi-directional hybridization/introgression between the two Nothofagus species and describe features of the populationś demography in the past. The settlement of a secondary contact zone in Nothofagus species around 42-44°S coincides with the phylogeographic breaks and hotspots of genetic diversity found in other plant and animal species in Patagonia

  5. Multi-stemmed trees of Nothofagus pumilio second-growth forest in Patagonia are formed by highly related individuals

    PubMed Central

    Till-Bottraud, Irène; Fajardo, Alex; Rioux, Delphine

    2012-01-01

    Background and Aims Multi-stemmed trees (tree clusters) in Nothofagus pumilio, a dominant tree species in Patagonia, are very uncommon and are restricted to the edge of second-growth forests following human-provoked fires. No vegetative reproduction has been reported so far. The genetic structure of multi-stemmed trees of this species was investigated and it was hypothesized that genets within a cluster were more closely related than average in the population. Methods Fifteen clusters (composed of at least three purported stems) and 15 single trees were sampled at the edge of a second-growth forest and genotyped using two amplified fragment length polymorphism (AFLP) primer pairs. We obtained 119 polymorphic markers that allowed clonality to be determined, together with sibship structure and relatedness among samples. Key Results Clonality was detected in seven clusters but all clusters had at least two different genotypes. Full sibs were found exclusively within clusters and in all clusters. Within a cluster, stems that were not identified as full sibs were often half sibs. Relatedness values for the full sibs and half sibs were higher than the theoretical values of 0·5 and 0·25 but the relatedness between clusters was very low. Conclusions Tree clusters that are merged at the edge of the second-growth forest of N. pumilio are composed of stems of the same genotype and of other genotypes that are highly related (but not always). It is suggested that this peculiar genetic structure results from a combination of several causes, including selection for merging of related individuals. PMID:22782238

  6. No evidence of carbon limitation with tree age and height in Nothofagus pumilio under Mediterranean and temperate climate conditions

    PubMed Central

    Piper, Frida I.; Fajardo, Alex

    2011-01-01

    Background and Aims Trees universally decrease their growth with age. Most explanations for this trend so far support the hypothesis that carbon (C) gain becomes limited with age; though very few studies have directly assessed the relative reductions of C gain and C demand with tree age. It has also been suggested that drought enhances the effect of C gain limitation in trees. Here tests were carried out to determine whether C gain limitation is causing the growth decay with tree age, and whether drought accentuates its effect. Methods The balance between C gain and C demand across tree age and height ranges was estimated. For this, the concentration of non-structural carbohydrates (NSCs) in stems and roots of trees of different ages and heights was measured in the deciduous temperate species Nothofagus pumilio. An ontogenetic decrease in NSCs indicates support for C limitation. Furthermore, the importance of drought in altering the C balance with ontogeny was assessed by sampling the same species in Mediterranean and humid climate locations in the southern Andes of Chile. Wood density (WD) and stable carbon isotope ratios (δ13C) were also determined to examine drought constraints on C gain. Key Results At both locations, it was effectively found that tree growth ultimately decreased with tree age and height. It was found, however, that NSC concentrations did not decrease with tree age or height when WD was considered, suggesting that C limitation is not the ultimate mechanism causing the age/height-related declining tree growth. δ13C decreased with tree age/height at the Mediterranean site only; drought effect increased with tree age/height, but this pattern was not mirrored by the levels of NSCs. Conclusions The results indicate that concentrations of C storage in N. pumilio trees do not decrease with tree age or height, and that reduced C assimilation due to summer drought does not alter this pattern. PMID:21852277

  7. Effectiveness of fencing and hunting to control Lama guanicoe browsing damage: Implications for Nothofagus pumilio regeneration in harvested forests.

    PubMed

    Martínez Pastur, Guillermo; Soler, Rosina; Ivancich, Horacio; Lencinas, María V; Bahamonde, Héctor; Peri, Pablo L

    2016-03-01

    Browsing damage by native ungulates is often to be considered one of the reasons of regeneration failure in Nothofagus pumilio silvicultural systems. Fencing and hunting in forests at regeneration phase have been proposed to mitigate browsing effects. This study aims to determine effectiveness of these control methods in harvested forests, evaluating browsing damage over regeneration, as well as climate-related constraints (freezing or desiccation). Forest structure and regeneration plots were established in two exclosures against native ungulates (Lama guanicoe) by wire fences in the Chilean portion of Tierra del Fuego island, where tree regeneration density, growth, abiotic damage and quality (multi-stems and base/stem deformation) were assessed. Exclosures did not influence regeneration density (at the initial stage with < 1.3 m high, and at the advanced stage with >1.3 m high). However, sapling height at 10-years old was significantly lower outside (40-50 cm high) than inside exclosures (80-100 cm), and also increased their annual height growth, probably as a hunting effect. Likewise, quality was better inside exclosures. Alongside browsing, abiotic conditions negatively influenced sapling quality in the regeneration phase (20%-28% of all seedlings), but greatly to taller plants (as those from inside exclosure). This highlights the importance of considering climatic factors when analysing browsing effects. For best results, control of guanaco in recently harvested areas by fencing should be applied in combination with a reduction of guanaco density through continuous hunting. The benefits of mitigation actions (fencing and hunting) on regeneration growth may shorten the regeneration phase period in shelterwood cutting forests (30-50% less time), but incremental costs must be analysed in the framework of management planning by means of long-term studies.

  8. Living on the edge: adaptive and plastic responses of the tree Nothofagus pumilio to a long-term transplant experiment predict rear-edge upward expansion.

    PubMed

    Mathiasen, Paula; Premoli, Andrea C

    2016-06-01

    Current climate change affects the competitive ability and reproductive success of many species, leading to local extinctions, adjustment to novel local conditions by phenotypic plasticity or rapid adaptation, or tracking their optima through range shifts. However, many species have limited ability to expand to suitable areas. Altitudinal gradients, with abrupt changes in abiotic conditions over short distances, represent "natural experiments" for the evaluation of ecological and evolutionary responses under scenarios of climate change. Nothofagus pumilio is the tree species which dominates as pure stands the montane forests of Patagonia. We evaluated the adaptive value of variation in quantitative traits of N. pumilio under contrasting conditions of the altitudinal gradient with a long-term reciprocal transplant experimental design. While high-elevation plants show little response in plant, leaf, and phenological traits to the experimental trials, low-elevation ones show greater plasticity in their responses to changing environments, particularly at high elevation. Our results suggest a relatively reduced potential for evolutionary adaptation of high-elevation genotypes, and a greater evolutionary potential of low-elevation ones. Under global warming scenarios of forest upslope migration, high-elevation variants may be outperformed by low-elevation ones during this process, leading to the local extinction and/or replacement of these genotypes. These results challenge previous models and predictions expected under global warming for altitudinal gradients, on which the leading edge is considered to be the upper treeline forests.

  9. Foliar nitrogen and phosphorus dynamics of three Chilean Nothofagus (Fagaceae) species in relation to leaf lifespan.

    PubMed

    Hevia, F; Minoletti O, M L; Decker, K L; Boerner, R E

    1999-03-01

    This study examined foliar nutrient dynamics and nutrient resorption (retranslocation) in three species of Chilean Nothofagus (Fagaceae) that differed in leaf lifespan and elevational distribution. In our central Chile study area the elevations at which these three species are most abundant increase from N. obliqua (deciduous) at low elevations to N. dombeyi at intermediate elevation and N. pumilio (deciduous) at higher elevations up to treeline. We sampled a single stand at 1680 m in which all three species co-occurred. Nothofagus dombeyi leaves were structurally heavier, with specific leaf mass approximately twice that of the two deciduous species. On a concentration basis, foliar N increased in the order N. dombeyi < N. pumilio < N. obliqua and foliar P increased in the order N. dombeyi < N. obliqua < N. pumilio. However, when the differences in specific leaf mass among species were taken into account by calculating N and P content on a leaf area basis, N. dombeyi had the greatest N and P content. N and P remained relatively constant throughout most of the 4-yr N. dombeyi leaf lifespan, then decreased prior to abscission. Nothofagus dombeyi resorbed significantly less N (44-50%) than did the two deciduous species (63-78%), both on proportional and absolute bases. In contrast, N. pumilio and N. dombeyi resorbed similar amounts of P prior to abscission (40-50%), whereas no significant resorption of P from leaves of N. obliqua was noted. We use these results to clarify the relative importance of environmental gradients associated with elevation vs. genetically fixed leaf lifespans in controlling the nutrient dynamics of these congeneric tree species.

  10. Pumilio genes from the Platyhelminthes.

    PubMed

    Koziol, Uriel; Marín, Monica; Castillo, Estela

    2008-01-01

    Pumilio proteins are proposed to have a conserved primordial function in the maintenance of proliferation in stem cells through post-transcriptional regulation. In this work, a search for pumilio homology domain (PUM-HD) sequences of pumilio genes from several Platyhelminthes species was performed, including representatives form Cestoda, Trematoda and Tricladida. Only one PUM-HD sequence was found in each triclad species; however, two PUM-HD homologues were found in all the parasitic species. These sequences formed two clearly separated clades: PlatyPum1, with sequences from all species, and PlatyPum2, composed exclusively of neodermatan sequences. Therefore, at least one duplication of the pumilio gene must have occurred before the divergence of cestodes and trematodes. Further duplications of PUM-HD were found in Fasciola hepatica, but these consist of retropseudogenes. This is the first comparative analysis of PUM-HD sequences in the Platyhelminthes and, more generally, in any lophotrochozoan phylum.

  11. Patterns of fungal diversity in New Zealand Nothofagus forests.

    PubMed

    Johnston, Peter R; Johansen, Renee B; Williams, Alexandra F R; Paula Wikie, J; Park, Duckchul

    2012-03-01

    The development of protocols for the conservation of fungi requires knowledge of the factors controlling their distribution, diversity, and community composition. Here we compare patterns of variation in fungal communities across New Zealand's Nothofagus forests, reportedly the most myco-diverse in New Zealand and hence potentially key to effective conservation of fungi in New Zealand. Diversity of leaf endophytic fungi, as assessed by culturing on agar plates, is assessed for three Nothofagus sp. growing in mixed stands from four sites. Host species was found to have a greater influence on fungal community assemblage than site. The leaf endophyte communities associated with Nothofagus solandri and Nothofagus fusca (both Nothofagus subgenus Fuscopora), were more similar to each other than either were to the community associated with Nothofagus menziesii (Nothofagus subgenus Lophozonia). The broad taxonomic groups isolated, identified on the basis of internal transcribed spacer (ITS) sequences, were similar to those found in similar studies from other parts of the world, and from an earlier study on the endophyte diversity in four podocarp species from New Zealand, but there were few matches at species level. Average levels of endophyte species diversity associated with single Nothofagus species and single podocarp species were similar, despite historical literature and collection data recording more than twice as many fungal species on average from the Nothofagus species. The significance of these findings to fungal conservation is discussed.

  12. Xanthophyllomyces dendrorhous (Phaffia rhodozyma) on stromata of Cyttaria hariotii in northwestern Patagonian Nothofagus forests.

    PubMed

    Libkind, Diego; Tognetti, Celia; Ruffini, Alejandra; Sampaio, José Paulo; Van Broock, María

    2011-01-01

    The occurrence and distribution of Xanthophyllomyces dendrorhous associated with Cyttaria hariotii parasitizing three Nothofagus species (N. dombeyi, N. antarctica and N. pumilio) in northwestern Patagonia (Argentina), as well as the factors that may affect this distribution were herein studied. Between 2000 and 2007, samples were obtained from 18 different locations. Based on physiological tests and morphological characteristics of sexual structures, 72 isolates were identified as X. dendrorhous. Representative strains were studied by MSP-PCR fingerprinting and sequence analysis of the ITS region. MSP-PCR fingerprints were similar for the newly isolated strains, and were also identical to the profiles of the strains previously found in this region. Patagonian strains appear to be a genetically uniform and distinct population, supporting the hypothesis that the association with different host species has determined genetically distinct X. dendrorhous populations worldwide. X. dendrorhous was recovered from N. dombeyi and N. antarctica. Approximately half the sampling sites and samples were positive for X. dendrorhous, but the isolation recovery rate was low. X. dendrorhous was absent in the early stages of ascostromata maturation, becoming more abundant in later stages. The present work represents a step forward in the understanding of the natural distribution and ecology of this biotechnologically relevant yeast.

  13. Low temperature responses of Nothofagus dombeyi and Nothofagus nitida, two evergreen species from south central Chile.

    PubMed

    Reyes-Díaz, M; Alberdi, M; Piper, F; Bravo, L A; Corcuera, L J

    2005-11-01

    Nothofagus dombeyi (Mirb.) Blume and Nothofagus nitida (Phil.) Krasser are closely related evergreen trees native to south central Chile. Nothofagus dombeyi is a pioneer in habitats subject to high daytime irradiances and nighttime freezing temperatures and has a wider altitudinal and latitudinal distribution than N. nitida, which is restricted to more oceanic climates. We postulated that N. dombeyi has a greater cold-acclimation capacity, expressed as a greater capacity to maintain a functional photosynthetic apparatus at low temperatures, than N. nitida. Because cold-acclimation may be related to the accumulation of cryoprotective substances, we investigated relationships between ice nucleation temperature (IN), freezing temperature (FT), and the temperature causing injury to 50% of the leaf tissues (LT(50)) on the one hand, and concentrations of total soluble carbohydrates (TSC), starch and proline on the other hand. Observations were made throughout a seasonal cycle in adults and seedlings in the field and in seedlings in the laboratory under cold-acclimation inductive and non-inductive conditions. In adults, LT(50) values were lower in N. dombeyi than in N. nitida, suggesting that N. dombeyi is the more frost tolerant species. Adults of both species tolerated freezing in autumn and winter but not in spring and summer. In the fall and winter, seedlings of N. dombeyi had a much lower LT(50) than those of N. nitida. Nothofagus nitida seedlings, in autumn and winter, exhibited freezing avoidance mechanisms. Although elevated TSC and proline concentrations may contribute to freezing tolerance in adults of both species, an increase in proline concentration is unlikely to be the dominant frost tolerance response in adults because proline concentrations were higher in N. nitida than in N. dombeyi. In seedlings, however, there were large differences in proline accumulation between species that may account for the difference between them in freezing tolerance. Starch

  14. Heterospecific Acoustic Interference: Effects on Calling in Oophaga pumilio

    PubMed Central

    Wong, Stefanie; Parada, Humberto; Narins, Peter M.

    2010-01-01

    Call rate suppression is a common short-term solution for avoiding acoustic interference in animals. It has been widely documented between and within frog species, but the effects of non-anuran calling on frog vocalizations is less well known. Heterospecific acoustic interference on the calling of Oophaga pumilio (Bauer, 1994) (formerly Dendrobates pumilio) males was studied in a lowland, wet tropical forest in SE Nicaragua. Acoustic playback experiments were conducted to characterize the responses of O. pumilio males to interfering calls of cicadas, two species of crickets and a sympatric dendrobatid frog, Phyllobates lugubris. Call rate, call bout duration, percent of time calling, dominant frequency and latency to first-call were analyzed. Significant call rate suppression was observed during all stimulus playbacks, yet no significant differences were found in spontaneous call rates during pre- and post-playback trials. Dominant frequency significantly decreased after P. lugubris playback and first-call latency significantly decreased in response to both cicada and tree cricket playbacks. These results provide robust evidence that O. pumilio males can dynamically modify their calling pattern in unique ways, depending on the source of the heterospecific acoustic interference. PMID:20953296

  15. The southernmost Andean Mountain soils: a toposequence from Nothofagus Forest to Sub Antarctic Tundra at Ushuaia, Tierra del Fuego

    NASA Astrophysics Data System (ADS)

    Firme Sá, Mariana M.; Schaefer, Carlos E.; Loureiro, Diego C.; Simas, Felipe N.; Francelino, Marcio R.; Senra, Eduardo O.

    2015-04-01

    Located at the southern tip of the Fuegian Andes Cordilhera, the Martial glacier witnessed a rapid process of retreat in the last century. Up to now little is known about the development and genesis of soils of this region. A toposequence of six soils, ranging from 430-925 m a.s.l, was investigated, with emphasis on genesis, chemical and mineralogical properties. The highest, youngest soil is located just below the Martial Glacier Martial Sur sector, and the lowest soils occur on sloping moraines under Nothofagus pumilio forests. Based on chemical, physical and mineralogical characteristics, the soils were classified according to the Soil taxonomy, being keyed out as Inceptisols and Entisols. Soil parent material of the soil is basically moraines, in which the predominant lithic components dominated by metamorphic rocks, with allochthonous contributions of wind-blown materials (very small fragments of volcanic glass) observed by hand lens in all horizons, except the highest profile under Tundra. In Nothofagus Deciduous Forests at the lowest part of the toposequence, poorly developed Inceptisols occur with Folistic horizons, with mixed "andic" and "spodic" characters, but with a predominance of andosolization (Andic Drystrocryepts). Under Tundra vegetation, Inceptisols are formed under hydromorphism and andosolization processes (Oxiaquic Dystrocrepts and Typic Dystrocrepts). On highland periglacial environments, soils without B horizon with strong evidence of cryoturbation and cryogenesis occur, without present-day permafrost down to 2 meters (Typic Cryorthents and Lithic Haploturbels). The mountain soils of Martial glacier generalize young, stony and rich in organic matter, with the exception of barely vegetated Tundra soils at higher altitudes. The forest soils are more acidic and have higher Al3+activity. All soils are dystrophic, except for the highest profile of the local periglacial environment. The organic carbon amounts are higher in forest soils and

  16. Introduced species and management of a Nothofagus/Austrocedrus forest.

    PubMed

    Simberloff, Daniel; Relva, Maria Andrea; Nunez, Martin

    2003-02-01

    Isla Victoria (Nahuel Huapi National Park, Argentina), a large island dominated by native Nothofagus and Austrocedrus forest, has old plantations of many introduced tree species, some of which are famed invaders of native ecosystems elsewhere. There are also large populations of introduced deer and shrubs that may interact in a complex way with the introduced trees, as well as a recently arrived population of wild boar. Long-standing concern that the introduced trees will invade and transform native forest may be unwarranted, as there is little evidence of progressive invasion, even close to the plantations, despite over 50 years of opportunity. Introduced and native shrubs allow scattered introduced trees to achieve substantial size in abandoned pastures, but in almost all areas neither the trees nor the shrubs appear to be spreading beyond these sites. These shrub communities may be stable rather than successional, but the technology for restoring them to native forest is uncertain and probably currently impractical. Any attempt to remove the exotic tree seedlings and saplings from native forest would probably create the very conditions that would favor colonization by exotic plants rather than native trees, while simply clear-cutting the plantations would be unlikely to lead to regeneration of Nothofagus or Austrocedrus. The key to maintaining native forest is preventing catastrophic fire, as several introduced trees and shrubs would be favored over native dominant trees in recolonization. Deer undoubtedly interact with both native and introduced trees and shrubs, but their net effect on native forest is not yet clear, and specific management of deer beyond the current hunting by staff is unwarranted, at least if preventing tree invasion is the goal. The steep terrain and shallow soil make the recently arrived boar a grave threat to the native forest. Eradication is probably feasible and should be attempted quickly.

  17. Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech).

    PubMed

    Knapp, Michael; Stöckler, Karen; Havell, David; Delsuc, Frédéric; Sebastiani, Federico; Lockhart, Peter J

    2005-01-01

    Nothofagus (southern beech), with an 80-million-year-old fossil record, has become iconic as a plant genus whose ancient Gondwanan relationships reach back into the Cretaceous era. Closely associated with Wegener's theory of "Kontinentaldrift", Nothofagus has been regarded as the "key genus in plant biogeography". This paradigm has the New Zealand species as passengers on a Moa's Ark that rafted away from other landmasses following the breakup of Gondwana. An alternative explanation for the current transoceanic distribution of species seems almost inconceivable given that Nothofagus seeds are generally thought to be poorly suited for dispersal across large distances or oceans. Here we test the Moa's Ark hypothesis using relaxed molecular clock methods in the analysis of a 7.2-kb fragment of the chloroplast genome. Our analyses provide the first unequivocal molecular clock evidence that, whilst some Nothofagus transoceanic distributions are consistent with vicariance, trans-Tasman Sea distributions can only be explained by long-distance dispersal. Thus, our analyses support the interpretation of an absence of Lophozonia and Fuscospora pollen types in the New Zealand Cretaceous fossil record as evidence for Tertiary dispersals of Nothofagus to New Zealand. Our findings contradict those from recent cladistic analyses of biogeographic data that have concluded transoceanic Nothofagus distributions can only be explained by vicariance events and subsequent extinction. They indicate that the biogeographic history of Nothofagus is more complex than envisaged under opposing polarised views expressed in the ongoing controversy over the relevance of dispersal and vicariance for explaining plant biodiversity. They provide motivation and justification for developing more complex hypotheses that seek to explain the origins of Southern Hemisphere biota.

  18. APUM5, encoding a Pumilio RNA binding protein, negatively regulates abiotic stress responsive gene expression

    PubMed Central

    2014-01-01

    Background A mutant screening was carried out previously to look for new genes related to the Cucumber mosaic virus infection response in Arabidopsis. A Pumilio RNA binding protein-coding gene, Arabidopsis Pumilio RNA binding protein 5 (APUM5), was obtained from this screening. Results APUM5 transcriptional profiling was carried out using a bioinformatics tool. We found that APUM5 was associated with both biotic and abiotic stress responses. However, bacterial and fungal pathogen infection susceptibility was not changed in APUM5 transgenic plants compared to that in wild type plants although APUM5 expression was induced upon pathogen infection. In contrast, APUM5 was involved in the abiotic stress response. 35S-APUM5 transgenic plants showed hypersensitive phenotypes under salt and drought stresses during germination, primary root elongation at the seedling stage, and at the vegetative stage in soil. We also showed that some abiotic stress-responsive genes were negatively regulated in 35S-APUM5 transgenic plants. The APUM5-Pumilio homology domain (PHD) protein bound to the 3′ untranslated region (UTR) of the abiotic stress-responsive genes which contained putative Pumilio RNA binding motifs at the 3′ UTR. Conclusions These results suggest that APUM5 may be a new post-transcriptional regulator of the abiotic stress response by direct binding of target genes 3′ UTRs. PMID:24666827

  19. Declining moisture availability in late Eocene Antarctica as deduced from Nothofagus sporopollenin δ13C

    NASA Astrophysics Data System (ADS)

    Griener, K. W.; Nelson, D. M.; Warny, S.

    2012-12-01

    Palynological data demonstrate that significant changes in vegetation and climate occurred at the Eocene-Oligocene (E-O) Boundary on the Antarctic Peninsula. These changes include decreases in terrestrial palynomorph abundance and diversity as well as dinoflagellate assemblages that reflect colder sea surface temperatures and increased glaciation (Warny and Askin, 2011). Understanding the factors controlling these changes in climate and vegetation is a topic of great interest. One area of remaining uncertainty is how the hydrologic regime varied during Antarctica's shift from greenhouse to icehouse conditions. For example, estimates of Antarctic precipitation from around the E-O boundary based on plant leaf margins (e.g. Francis et al., 2008), clay mineralogy (e.g. Christian and Kennett, 1997), and models (Thorn and DeConto 2006) are vastly different. We used a moving-wire device interfaced with an isotope-ratio mass spectrometer (Sessions et al., 2005; Nelson et al., 2008) to analyze δ13C of small quantities of Nothofagus sporopollenin extracted from Antarctic Eocene SHALDRIL cores from ~35.9 Mya, just prior to the E-O Boundary (Bohaty et al., 2011). We also analyzed δ13C of modern Nothofagus sporopollenin from herbaria specimens and related these results to historical climate data. Our modern data show that carbon isotope discrimination (Δ) of Nothofagus sporopollenin is positively correlated with mean annual and growing-season precipitation, consistent with prior studies that demonstrate a strong relationship between Δ and water availability in C3 plants. Eocene Nothofagus Δ values progressively decreased through time, implying a decline in moisture availability. There is a close correlation between Nothofagus palynomorph abundance (Warny and Askin, 2011) and Δ, indicating that Nothofagus abundance declined in response to decreasing moisture availability. We consider changes in sea surface temperatures as well as increased glaciation as possible causes

  20. Regeneration mode affects spatial genetic structure of Nothofagus dombeyi forests.

    PubMed

    Premoli, Andrea C; Kitzberger, Thomas

    2005-07-01

    Disturbance may generate population bottlenecks by reducing population size and the number of founders establishing a new colony. We tested the hypothesis that the scale of disturbance affects the levels of genetic diversity and the spatial distribution of genotypes in naturally regenerating stands of Nothofagus dombeyi, an evergreen angiosperm tree, in northwestern Patagonia. At similar spatial scales, we predicted that old-growth stands characterized by fine-scale gap phase dynamics would be genetically diverse due to restricted gene flow among temporal and spatially isolated gaps. In contrast, young massively regenerated postfire cohorts resulting from coarse-scale disturbances would be genetically more homogeneous. At each of three paired old-growth and postfire stands a minimum of 50 trees were mapped and sampled within 1 ha. Fresh tissue was collected for isozyme analysis from a total of 361 trees along with tree cores and diameters. Tree age distributions reflected the dominant modes of regeneration. Six out of nine analysed loci were polymorphic. Mean genetic diversity parameters were greater but not significant in mature stands. Fixation indices suggested significant heterozygous deficit at two-thirds of possible tests indicating a Wahlund effect due to local recruitment of related seeds. F(ST) indicated moderate between-stand divergence. Mature stands concentrated half of positively like joins and yielded significant (P < 0.05) autocorrelation coefficients at small distance classes (< 20 m). Fine-scale patch dynamics within mature stands favours the maintenance of fine-scale genetic structure as a result of shade intolerance and local seed dispersal. Conversely, postfire stands suffer the effects of genetic drift given that a few reproductive trees produce a somewhat impoverished and genetically uniform progeny. Bottleneck effects will depend upon the density of remnant trees which could also be a function of the severity of fire.

  1. Development of genomic resources for Nothofagus species using next-generation sequencing data.

    PubMed

    El Mujtar, V A; Gallo, L A; Lang, T; Garnier-Géré, P

    2014-11-01

    Using next-generation sequencing, we developed the first whole-genome resources for two hybridizing Nothofagus species of the Patagonian forests that crucially lack genomic data, despite their ecological and industrial value. A de novo assembly strategy combining base quality control and optimization of the putative chloroplast gene map yielded ~32,000 contigs from 43% of the reads produced. With 12.5% of assembled reads, we covered ~96% of the chloroplast genome and ~70% of the mitochondrial gene content, providing functional and structural annotations for 112 and 52 genes, respectively. Functional annotation was possible on 15% of the contigs, with ~1750 potentially novel nuclear genes identified for Nothofagus species. We estimated that the new resources (13.41 Mb in total) included ~4000 gene regions representing ~6.5% of the expected genic partition of the genome, the remaining contigs potentially being nongenic DNA. A high-quality single nucleotide polymorphisms resource was developed by comparing various filtering methods, and preliminary results indicate a strong conservation of cpDNA genomes in contrast to numerous exclusive nuclear polymorphisms in both species. Finally, we characterized 2274 potential simple sequence repeat (SSR) loci, designed primers for 769 of them and validated nine of 29 loci in 42 individuals per species. Nothofagus obliqua had more alleles (4.89) on average than N. nervosa (2.89), 8 SSRs were efficient to discriminate species, and three were successfully transferred in three other Nothofagus species. These resources will greatly help for future inferences of demographic, adaptive and hybridizing events in Nothofagus species, and for conserving and managing natural populations. © 2014 John Wiley & Sons Ltd.

  2. Structures of Human Pumilio with Noncognate RNAs Reveal Molecular Mechanisms for Binding Promiscuity

    SciTech Connect

    Gupta,Y.; Nair, D.; Wharton, R.; Aggarwal, A.

    2008-01-01

    Pumilio is a founder member of the evolutionarily conserved Puf family of RNA-binding proteins that control a number of physiological processes in eukaryotes. A structure of human Pumilio (hPum) Puf domain bound to a Drosophila regulatory sequence showed that each Puf repeat recognizes a single nucleotide. Puf domains in general bind promiscuously to a large set of degenerate sequences, but the structural basis for this promiscuity has been unclear. Here, we describe the structures of hPum Puf domain complexed to two noncognate RNAs, CycBreverse and Puf5. In each complex, one of the nucleotides is ejected from the binding surface, in effect, acting as a 'spacer.' The complexes also reveal the plasticity of several Puf repeats, which recognize noncanonical nucleotides. Together, these complexes provide a molecular basis for recognition of degenerate binding sites, which significantly increases the number of mRNAs targeted for regulation by Puf proteins in vivo.

  3. Characterisation of ectomycorrhizal formation by the exotic fungus Amanita muscaria with Nothofagus cunninghamii in Victoria, Australia.

    PubMed

    Dunk, Christopher William; Lebel, Teresa; Keane, Philip J

    2012-02-01

    The occurrence of the exotic ectomycorrhizal fungus Amanita muscaria in a mixed Nothofagus-Eucalyptus native forest was investigated to determine if A. muscaria has switched hosts to form a successful association with a native tree species in a natural environment. A mycorrhizal morphotype consistently found beneath A. muscaria sporocarps was examined, and a range of morphological and anatomical characteristics in common with those described for ectomycorrhizae formed by A. muscaria on a broad range of hosts were observed. A full description is provided. The likely plant associate was determined to be Nothofagus cunninghamii based upon anatomy of the roots. Analysis of ITS-1 and ITS-2 regions of nuclear ribosomal DNA sequences confirmed the identities of both fungal and plant associates. These findings represent conclusive evidence of the invasion of a non-indigenous ectomycorrhizal fungus into native forest and highlight the ecological implications of this discovery.

  4. Early Miocene Nothofagus in Antarctica based on fossil leaves from the Transantarctic Mountains

    NASA Astrophysics Data System (ADS)

    Wrobleski, S. A.; Ashworth, A. C.; Lewis, A. R.

    2014-12-01

    Nothofagus (Southern Beech) is the most widely reported plant from Cenozoic Antarctic fossil assemblages. Most of the fossils are of pollen morphotypes and it is assumed that the plants the pollen represents were growing on the continent. However, because of the uncertainties with systematics, long-distance dispersal, and reworking, it has been difficult to interpret the assemblages in terms of paleoenvironments and paleoclimate. Here, we report an in situ assemblage of Nothofagus leaves and pollen from the Friis Hills (77⁰ 45'S, 161⁰ 28'E). The leaves are preserved as carbonaceous impressions in brown, fissile shales that represent the deposits of a lake occupying a glacial valley. The leaves most probably accumulated from deciduous shrubs. Based on the stratigraphic relationship to a tephra with a 40 Ar/39 Ar age of c. 20 Ma, the leaf assemblage is of early Miocene age. Nothofagus pollen from the shale suggests that at least 3 species were represented. A total of 227 leaves were examined and lengths, widths, and areas recorded. The preservation is generally good but only a few of the specimens represent complete leaves; the spectrum is 30-100%. Plots of the measurements of the leaves provide a summary of size variation but were otherwise not useful for separating out different taxa . The most useful characters for establishing differences between the leaves were the leaf margins, of which three or four types were distinguished: 1. margins entire or finely serrate between ribs; 2. margins with one or two convex lobes between the ribs; 3. margins with convex lobes over the ribs. The leaf study indicates that three or possibly four species were co-inhabiting the valley in the early Miocene and were part of a dynamic vegetation that colonized the valley with each deglaciation. A possible analog today would be at low elevations in Tierra del Fuego where three species of Nothofagus coexist. The stem diameters of abundant wood preserved in adjacent facies indicates

  5. Regulated Pumilio-2 binding controls RINGO/Spy mRNA translation and CPEB activation.

    PubMed

    Padmanabhan, Kiran; Richter, Joel D

    2006-01-15

    CPEB is a sequence-specific RNA-binding protein that controls the polyadenylation-induced translation of mos and cyclin B1 mRNAs in maturing Xenopus oocytes. CPEB activity requires not only the phosphorylation of S174, but also the synthesis of a heretofore-unknown upstream effector molecule. We show that the synthesis of RINGO/Spy, an atypical activator of cyclin-dependent kinases (cdks), is necessary for CPEB-directed polyadenylation. Deletion analysis and mRNA reporter assays show that a cis element in the RINGO/Spy 3'UTR is necessary for translational repression in immature (G2-arrested) oocytes. The repression is mediated by 3'UTR Pumilio-Binding Elements (PBEs), and by its binding protein Pumilio 2 (Pum2). Pum2 also interacts with the Xenopus homolog of human Deleted for Azoospermia-like (DAZL) and the embryonic poly(A)-binding protein (ePAB). Following the induction of maturation, Pum2 dissociates not only from RINGO/Spy mRNA, but from XDAZL and ePAB as well; as a consequence, RINGO/Spy mRNA is translated. These results demonstrate that a reversible Pum2 interaction controls RINGO/Spy mRNA translation and, as a result, CPEB-mediated cytoplasmic polyadenylation.

  6. Regulated Pumilio-2 binding controls RINGO/Spy mRNA translation and CPEB activation

    PubMed Central

    Padmanabhan, Kiran; Richter, Joel D.

    2006-01-01

    CPEB is a sequence-specific RNA-binding protein that controls the polyadenylation-induced translation of mos and cyclin B1 mRNAs in maturing Xenopus oocytes. CPEB activity requires not only the phosphorylation of S174, but also the synthesis of a heretofore-unknown upstream effector molecule. We show that the synthesis of RINGO/Spy, an atypical activator of cyclin-dependent kinases (cdks), is necessary for CPEB-directed polyadenylation. Deletion analysis and mRNA reporter assays show that a cis element in the RINGO/Spy 3′UTR is necessary for translational repression in immature (G2-arrested) oocytes. The repression is mediated by 3′UTR Pumilio-Binding Elements (PBEs), and by its binding protein Pumilio 2 (Pum2). Pum2 also interacts with the Xenopus homolog of human Deleted for Azoospermia-like (DAZL) and the embryonic poly(A)-binding protein (ePAB). Following the induction of maturation, Pum2 dissociates not only from RINGO/Spy mRNA, but from XDAZL and ePAB as well; as a consequence, RINGO/Spy mRNA is translated. These results demonstrate that a reversible Pum2 interaction controls RINGO/Spy mRNA translation and, as a result, CPEB-mediated cytoplasmic polyadenylation. PMID:16418484

  7. Variable Alkaloid Defenses in the Dendrobatid Poison Frog Oophaga pumilio are Perceived as Differences in Palatability to Arthropods.

    PubMed

    Bolton, Sarah K; Dickerson, Kelsie; Saporito, Ralph A

    2017-03-01

    Conspicuously colored dendrobatid frogs sequester alkaloid defenses from dietary arthropods, resulting in considerable alkaloid variation among populations; however, little is known about how variation is perceived as a defense against predators. Previous studies have found variable alkaloids in the dendrobatid Oophaga pumilio to be associated with differences in toxicity to laboratory mice, suggesting variable defenses are important. Arthropods are natural predators that use chemoreception to detect prey, including frogs, and may therefore perceive variation in alkaloid profiles as differences in palatability. The goal of the present study is to determine how arthropods respond to variable alkaloid defenses in O. pumilio. Frog alkaloids were sampled from individual O. pumilio from ten geographic locations throughout the Bocas del Toro region of Panama and the Caribbean coast of Costa Rica. Alkaloid extracts were used in feeding bioassays with the vinegar fly Drosophila melanogaster and the ant Ectatomma ruidum. Both species of arthropods fed significantly less on frog alkaloid extracts when compared to controls, and differences in alkaloid palatability were observed among frog populations, as well as between sexes and life stages within a population. Differences in alkaloid quantity, richness, and type were the main predictors of arthropod palatability. Our findings also represent the first direct evidence of a palatability spectrum in a vertebrate that sequesters chemical defenses from dietary sources. Further, the presence of a palatability spectrum suggests that variable alkaloid defenses in O. pumilio are ecologically relevant and play an important role in natural predator-prey interactions, particularly with respect to arthropod predators.

  8. Maternally derived chemical defences are an effective deterrent against some predators of poison frog tadpoles (Oophaga pumilio)

    PubMed Central

    Stynoski, Jennifer L.; Shelton, Georgia; Stynoski, Peter

    2014-01-01

    Parents defend their young in many ways, including provisioning chemical defences. Recent work in a poison frog system offers the first example of an animal that provisions its young with alkaloids after hatching or birth rather than before. But it is not yet known whether maternally derived alkaloids are an effective defence against offspring predators. We identified the predators of Oophaga pumilio tadpoles and conducted laboratory and field choice tests to determine whether predators are deterred by alkaloids in tadpoles. We found that snakes, spiders and beetle larvae are common predators of O. pumilio tadpoles. Snakes were not deterred by alkaloids in tadpoles. However, spiders were less likely to consume mother-fed O. pumilio tadpoles than either alkaloid-free tadpoles of the red-eyed treefrog, Agalychnis callidryas, or alkaloid-free O. pumilio tadpoles that had been hand-fed with A. callidryas eggs. Thus, maternally derived alkaloids reduce the risk of predation for tadpoles, but only against some predators. PMID:24850895

  9. Differences in prolactin levels between three alternative male reproductive tactics in striped mice (Rhabdomys pumilio)

    PubMed Central

    Schradin, Carsten

    2008-01-01

    In male fishes, birds and mammals, increased prolactin secretion is thought to play a role in species showing paternal behaviours. This hypothesis was investigated in the striped mouse (Rhabdomys pumilio). This paper compares serum prolactin levels in 71 free-living male striped mice following three different reproductive tactics: (i) paternal group-living breeders, (ii) alloparental philopatric group-living males, and (iii) roaming non-paternal solitary males. Prolactin levels of breeding males were significantly higher than that of roamers. Alloparental philopatric males had low prolactin levels, which concur with studies of cooperatively breeding mammals, but contrasts with studies of cooperatively breeding birds. Both breeding males and females showed a decrease in prolactin levels after the breeding season, but not alloparental philopatric males. Prolactin levels were correlated with neither corticosterone levels nor age. These results are in agreement with the hypothesis that prolactin is one proximate mechanism of male reproductive tactics, possibly regulating differences in male parental care. PMID:18230588

  10. Carotenoid supplementation enhances reproductive success in captive strawberry poison frogs (Oophaga pumilio).

    PubMed

    Dugas, Matthew B; Yeager, Justin; Richards-Zawacki, Corinne L

    2013-01-01

    Amphibians are currently experiencing the most severe declines in biodiversity of any vertebrate, and their requirements for successful reproduction are poorly understood. Here, we show that supplementing the diet of prey items (fruit flies) with carotenoids has strong positive effects on the reproduction of captive strawberry poison frogs (Oophaga pumilio), substantially increasing the number of metamorphs produced by pairs. This improved reproduction most likely arose via increases in the quality of both the fertilized eggs from which tadpoles develop and trophic eggs that are fed to tadpoles by mothers. Frogs in this colony had previously been diagnosed with a Vitamin A deficiency, and this supplementation may have resolved this issue. These results support growing evidence of the importance of carotenoids in vertebrate reproduction and highlight the nuanced ways in which nutrition constrains captive populations.

  11. A conserved abundant cytoplasmic long noncoding RNA modulates repression by Pumilio proteins in human cells

    PubMed Central

    Tichon, Ailone; Gil, Noa; Lubelsky, Yoav; Havkin Solomon, Tal; Lemze, Doron; Itzkovitz, Shalev; Stern-Ginossar, Noam; Ulitsky, Igor

    2016-01-01

    Thousands of long noncoding RNA (lncRNA) genes are encoded in the human genome, and hundreds of them are evolutionarily conserved, but their functions and modes of action remain largely obscure. Particularly enigmatic lncRNAs are those that are exported to the cytoplasm, including NORAD—an abundant and highly conserved cytoplasmic lncRNA. Here we show that most of the sequence of NORAD is comprised of repetitive units that together contain at least 17 functional binding sites for the two mammalian Pumilio homologues. Through binding to PUM1 and PUM2, NORAD modulates the mRNA levels of their targets, which are enriched for genes involved in chromosome segregation during cell division. Our results suggest that some cytoplasmic lncRNAs function by modulating the activities of RNA-binding proteins, an activity which positions them at key junctions of cellular signalling pathways. PMID:27406171

  12. Thermal energy dissipation and its components in two developmental stages of a shade-tolerant species, Nothofagus nitida, and a shade-intolerant species, Nothofagus dombeyi.

    PubMed

    Reyes-Díaz, Marjorie; Ivanov, Alexander G; Huner, Norman P A; Alberdi, Miren; Corcuera, Luis J; Bravo, León A

    2009-05-01

    Nothofagus dombeyi (Mirb.) Blume and Nothofagus nitida (Phil.) Krasser, two evergreens in the South Chilean forest, regenerate in open habitats and under the canopy, respectively. Both overtop the forest canopy when they are in the adult stage, suggesting that their photoprotective mechanisms differ in ontogenetic dynamics. We postulated that N. nitida, a shade-tolerant species increases its capacity to tolerate photoinhibitory conditions (low temperature and high irradiance) by thermal energy dissipation of excess energy during its transition from the seedling to the adult stage, whereas N. dombeyi, a shade-intolerant species, maintains a high capacity for photoprotection by thermal energy dissipation from the seedling to the adult stage. To test this hypothesis, the main photoprotective mechanisms in plants - the fast- and slow-relaxing components of thermal energy dissipation (NPQ, non-photochemical quenching) NPQ(F) and NPQ(S), respectively, and state transitions - were studied in seedlings and adults of both species grown in their natural habitats and in a common garden. In adults, NPQ(F) and NPQ(S) did not differ between species and seasons. The greatest differences in these parameters were observed in seedlings. The xanthophyll cycle was more active in N. dombeyi seedlings than in N. nitida seedlings at low temperature and high irradiance, consistent with a higher NPQ(F) in N. dombeyi. Under all study conditions, N. nitida seedlings had higher NPQ(S) than N. dombeyi seedlings. The state transition capability was higher in N. nitida seedlings than in N. dombeyi seedlings. Therefore, although (shade-intolerant) N. dombeyi was able to thermally dissipate the excess absorbed energy, under natural conditions its photochemical energy quenching was efficient in both developmental stages, decreasing its need for thermal dissipation. In contrast, the seedlings of N. nitida were more sensitive to photoinhibition than the adult trees, suggesting a change from shade

  13. Next generation sequencing yields the complete mitochondrial genome of the scarce blue-tailed damselfly, Ischnura pumilio.

    PubMed

    Lorenzo-Carballa, M Olalla; Thompson, David J; Cordero-Rivera, Adolfo; Watts, Phillip C

    2014-08-01

    We report the entire mitochondrial genome of the scarce blue-tailed damselfly, Ischnura pumilio (Odonata, Coenagrionidae), using next-generation sequencing on genomic DNA. A de novo assembly provided a single contiguous sequence of 15,250 bp that contained the A + T-rich region and all standard coding regions; gene configuration is similar to other odonates and comprises 13 protein-coding genes, two rRNA genes (12 S and 16 S rRNA) and 22 tRNA genes. We found a unique intergenic spacer in I. pumilio and confirm that the intergenic spacer s5 likely represents a synapomorphy between Anisoptera and Zygoptera. This is the first mitogenome sequence obtained for a member of the Coenagrionidae and demonstrates how next-generation sequencing technology can obtain mtDNA genome sequences without prior sample processing or primer design.

  14. Evidence of Pliocene Nothofagus in Antarctica from Pliocene marine sedimentary deposits (DSDP Site 274)

    USGS Publications Warehouse

    Fleming, R.F.; Barron, J.A.

    1996-01-01

    Microfossil assemblages in Pliocene sediments from DSDP Site 274 (68??59.81???S, 173??25.64???E) provide data on the age of the sediments and suggest the presence of Nothofagus (southern beech) in Antarctica during the Pliocene. A suite of 17 samples was collected in an interval from Samples 28-274-6R-1, 83-87 cm to 28-274-11R-4, 73-77 cm (48.33-100.29 mbsf). Biostratigraphic study of the abundant diatom assemblages combined with published radiolarian data indicates that the sample interval ranges in age from 5.0 to 2.2 Ma, with an apparent unconformity between about 3.8 and 3.2 Ma. Nothofagidites (the genus for fossil pollen referable to Nothofagus) occurs throughout the interval, as well as pollen and spores with known stratigraphic ranges that unequivocally indicate reworking from older rocks. Species of Nothofagidites recovered include N. asperus, N. brachyspinulosus, N. flemingii, N. senectus, and N. sp. cf. N. lachlaniae; the latter form is previously known from the Sirius Group in the Transantarctic Mountains. Abundant palynomorphs were recovered in only three of the samples from Site 274 (Samples 28-274-9R-2, 15-19 cm; 28-274-9R-2, 48-52 cm; and 28-274-9R-2, 65-69 cm). Based on the diatom and radiolarian biostratigraphic data, the ages of these samples range from 3.00 to 3.01 Ma. The relative abundance of N. sp. cf. N. lachlaniae in the three samples is an order of magnitude higher than relative abundances for the other species of Nothofagidites in the same samples. The significantly higher relative abundance of N. sp. cf. N. lachlaniae suggests that this pollen was derived from trees of Nothofagus that were living in Antarctica during the mid Pliocene. Diatom assemblages from these three samples indicate that sediments in this interval were rapidly deposited as biogenic oozes in an open-ocean setting relatively free of sea ice, thus decreasing the possibility of reworking from a single source bed rich in N. sp. cf. N. lachlaniae. Clearly, more detailed

  15. Engineered proteins with Pumilio/fem-3 mRNA binding factor scaffold to manipulate RNA metabolism.

    PubMed

    Wang, Yang; Wang, Zefeng; Tanaka Hall, Traci M

    2013-08-01

    Pumilio/fem-3 mRNA binding factor proteins are characterized by a sequence-specific RNA-binding domain. This unique single-stranded RNA recognition module, whose sequence specificity can be reprogrammed, has been fused with functional modules to engineer protein factors with various functions. We summarize the advances made with respect to developing RNA regulatory tools, as well as opportunities for the future.

  16. Transcriptome survey of Patagonian southern beech Nothofagus nervosa (= N. Alpina): assembly, annotation and molecular marker discovery.

    PubMed

    Torales, Susana L; Rivarola, Máximo; Pomponio, María F; Fernández, Paula; Acuña, Cintia V; Marchelli, Paula; Gonzalez, Sergio; Azpilicueta, María M; Hopp, Horacio Esteban; Gallo, Leonardo A; Paniego, Norma B; Poltri, Susana N Marcucci

    2012-07-02

    Nothofagus nervosa is one of the most emblematic native tree species of Patagonian temperate forests. Here, the shotgun RNA-sequencing (RNA-Seq) of the transcriptome of N. nervosa, including de novo assembly, functional annotation, and in silico discovery of potential molecular markers to support population and associations genetic studies, are described. Pyrosequencing of a young leaf cDNA library generated a total of 111,814 high quality reads, with an average length of 447 bp. De novo assembly using Newbler resulted into 3,005 tentative isotigs (including alternative transcripts). The non-assembled sequences (singletons) were clustered with CD-HIT-454 to identify natural and artificial duplicates from pyrosequencing reads, leading to 21,881 unique singletons. 15,497 out of 24,886 non-redundant sequences or unigenes, were successfully annotated against a plant protein database. A substantial number of simple sequence repeat markers (SSRs) were discovered in the assembled and annotated sequences. More than 40% of the SSR sequences were inside ORF sequences. To confirm the validity of these predicted markers, a subset of 73 SSRs selected through functional annotation evidences were successfully amplified from six seedlings DNA samples, being 14 polymorphic. This paper is the first report that shows a highly precise representation of the mRNAs diversity present in young leaves of a native South American tree, N. nervosa, as well as its in silico deduced putative functionality. The reported Nothofagus transcriptome sequences represent a unique resource for genetic studies and provide a tool to discover genes of interest and genetic markers that will greatly aid questions involving evolution, ecology, and conservation using genetic and genomic approaches in the genus.

  17. Transcriptome survey of Patagonian southern beech Nothofagus nervosa (= N. Alpina): assembly, annotation and molecular marker discovery

    PubMed Central

    2012-01-01

    Background Nothofagus nervosa is one of the most emblematic native tree species of Patagonian temperate forests. Here, the shotgun RNA-sequencing (RNA-Seq) of the transcriptome of N. nervosa, including de novo assembly, functional annotation, and in silico discovery of potential molecular markers to support population and associations genetic studies, are described. Results Pyrosequencing of a young leaf cDNA library generated a total of 111,814 high quality reads, with an average length of 447 bp. De novo assembly using Newbler resulted into 3,005 tentative isotigs (including alternative transcripts). The non-assembled sequences (singletons) were clustered with CD-HIT-454 to identify natural and artificial duplicates from pyrosequencing reads, leading to 21,881 unique singletons. 15,497 out of 24,886 non-redundant sequences or unigenes, were successfully annotated against a plant protein database. A substantial number of simple sequence repeat markers (SSRs) were discovered in the assembled and annotated sequences. More than 40% of the SSR sequences were inside ORF sequences. To confirm the validity of these predicted markers, a subset of 73 SSRs selected through functional annotation evidences were successfully amplified from six seedlings DNA samples, being 14 polymorphic. Conclusions This paper is the first report that shows a highly precise representation of the mRNAs diversity present in young leaves of a native South American tree, N. nervosa, as well as its in silico deduced putative functionality. The reported Nothofagus transcriptome sequences represent a unique resource for genetic studies and provide a tool to discover genes of interest and genetic markers that will greatly aid questions involving evolution, ecology, and conservation using genetic and genomic approaches in the genus. PMID:22747958

  18. Mistletoes and epiphytic lichens contribute to litter input in Nothofagus antarctica forests

    NASA Astrophysics Data System (ADS)

    Soler, Rosina; Pastur, Guillermo Martínez; Lencinas, María Vanessa; Peri, Pablo Luis

    2015-10-01

    Litter input is one of the key components that define nutrient cycling in forests and the majority of studies only consider the tree components of litterfall. However, epiphytic species can play a crucial role in litter input throughout the growing season. This work evaluates changes in litter production by mistletoe (Misodendrum sp.) and epiphytic lichen (Usnea sp.), related to crown cover in mature unmanaged, second-growth and managed (thinned for silvopastoral use) forests in Tierra del Fuego (Argentina). We used plastic traps to collect litterfall biomass from trees, lichens and mistletoes on a monthly basis over three consecutive years. Tree litter was considerable during autumn (March to May), which is typical of Nothofagus deciduous species in the Southern hemisphere. In contrast, peak litterfall from mistletoes and lichens occurred during spring and summer seasons. Tree litter (1954-3398 kg dry matter ha-1 year-1) was correlated with crown cover gradient being highest in second-growth forests and lowest in thinned sites. While litter input from mistletoes did not vary among forest types (307-333 kg dry matter ha-1 year-1), lichen litter (11-40 kg dry matter ha-1 year-1) was higher in unmanaged and thinned mature forests despite differences in tree crown cover. Contrary to what we expected, the management practices investigated here did not affect the biomass of canopy communities compared to unmanaged mature forests. Mistletoes and lichens significantly increased the spatial (forest type) and temporal complexity (extended period of falling) of litterfall in Nothofagus antarctica forests. This study provides a starting point to understand the ecological relevance of canopy communities in the Patagonian forests of southern Argentina.

  19. Seed dormancy responses to temperature relate to Nothofagus species distribution and determine temporal patterns of germination across altitudes in Patagonia.

    PubMed

    Arana, María V; Gonzalez-Polo, Marina; Martinez-Meier, Alejandro; Gallo, Leonardo A; Benech-Arnold, Roberto L; Sánchez, Rodolfo A; Batlla, Diego

    2016-01-01

    Seeds integrate environmental cues that modulate their dormancy and germination. Although many mechanisms have been identified in laboratory experiments, their contribution to germination dynamics in existing communities and their involvement in defining species habitats remain elusive. By coupling mathematical models with ecological data we investigated the contribution of seed temperature responses to the dynamics of germination of three Nothofagus species that are sharply distributed across different altitudes in the Patagonian Andes. Seed responsiveness to temperature of the three Nothofagus species was linked to the thermal characteristics of their preferred ecological niche. In their natural distribution range, there was overlap in the timing of germination of the species, which was restricted to mid-spring. By contrast, outside their species distribution range, germination was temporally uncoupled with altitude. This phenomenon was described mathematically by the interplay between interspecific differences in seed population thermal parameters and the range in soil thermic environments across different altitudes. The observed interspecific variations in seed responsiveness to temperature and its environmental regulation, constitute a major determinant of the dynamics of Nothofagus germination across elevations. This phenomenon likely contributes to the maintenance of patterns of species abundance across altitude by placing germinated seeds in a favorable environment for plant growth.

  20. Intestinal Helminths Recovered from Humans in Xieng Khouang Province, Lao PDR with a Particular Note on Haplorchis pumilio Infection.

    PubMed

    Chai, Jong-Yil; Sohn, Woon-Mok; Jung, Bong-Kwang; Yong, Tai-Soon; Eom, Keeseon S; Min, Duk-Young; Insisiengmay, Bounnaloth; Insisiengmay, Sithat; Phommasack, Bounlay; Rim, Han-Jong

    2015-08-01

    A survey of intestinal helminths was undertaken in riparian people in Xieng Khouang Province, Lao PDR. Fecal specimens were collected from 643 people (289 males and 354 females) residing in 4 districts (Nonghet, Kham, Phoukout, and Pek) and were examined by the Kato-Katz technique. The overall helminth egg positive rate was 41.2%, and hookworms revealed the highest prevalence (32.7%) followed by Trichuris trichiura (7.3%) and Ascaris lumbricoides (5.6%). The positive rate for small trematode eggs (STE), which may include Opisthorchis viverrini, heterophyids, and lecithodendriids, was 4.4%. For recovery of adult helminths, 12 STE or nematode/cestode egg-positive people were treated with 40 mg/kg praziquantel and 15 mg/kg pyrantel pamoate, and then purged. Mixed infections with 2 Haplorchis species (H. pumilio and H. taichui), Centrocestus formosanus, Opisthorchis viverrini, a species of cestode (Taenia saginata), and several species of nematodes including hookworms and Enterobius vermicularis were detected. The worm load for trematodes was the highest for H. pumilio with an average of 283.5 specimens per infected person followed by C. formosanus, H. taichui, and O. viverrini. The worm load for nematodes was the highest for hookworms (21.5/infected case) followed by E. vermicularis (3.2/infected case). The results revealed that the surveyed areas of Xieng Khouang Province, Lao PDR are endemic areas of various species of intestinal helminths. The STE found in the surveyed population were verified to be those of heterophyids, particularly H. pumilio.

  1. Intestinal Helminths Recovered from Humans in Xieng Khouang Province, Lao PDR with a Particular Note on Haplorchis pumilio Infection

    PubMed Central

    Chai, Jong-Yil; Sohn, Woon-Mok; Jung, Bong-Kwang; Yong, Tai-Soon; Eom, Keeseon S.; Min, Duk-Young; Insisiengmay, Bounnaloth; Insisiengmay, Sithat; Phommasack, Bounlay; Rim, Han-Jong

    2015-01-01

    A survey of intestinal helminths was undertaken in riparian people in Xieng Khouang Province, Lao PDR. Fecal specimens were collected from 643 people (289 males and 354 females) residing in 4 districts (Nonghet, Kham, Phoukout, and Pek) and were examined by the Kato-Katz technique. The overall helminth egg positive rate was 41.2%, and hookworms revealed the highest prevalence (32.7%) followed by Trichuris trichiura (7.3%) and Ascaris lumbricoides (5.6%). The positive rate for small trematode eggs (STE), which may include Opisthorchis viverrini, heterophyids, and lecithodendriids, was 4.4%. For recovery of adult helminths, 12 STE or nematode/cestode egg-positive people were treated with 40 mg/kg praziquantel and 15 mg/kg pyrantel pamoate, and then purged. Mixed infections with 2 Haplorchis species (H. pumilio and H. taichui), Centrocestus formosanus, Opisthorchis viverrini, a species of cestode (Taenia saginata), and several species of nematodes including hookworms and Enterobius vermicularis were detected. The worm load for trematodes was the highest for H. pumilio with an average of 283.5 specimens per infected person followed by C. formosanus, H. taichui, and O. viverrini. The worm load for nematodes was the highest for hookworms (21.5/infected case) followed by E. vermicularis (3.2/infected case). The results revealed that the surveyed areas of Xieng Khouang Province, Lao PDR are endemic areas of various species of intestinal helminths. The STE found in the surveyed population were verified to be those of heterophyids, particularly H. pumilio. PMID:26323842

  2. A FACS-based screening strategy to assess sequence-specific RNA-binding of Pumilio protein variants in E. coli.

    PubMed

    Kellermann, Stefanie J; Rentmeister, Andrea

    2017-01-01

    Sequence-specific and programmable binding of proteins to RNA bears the potential to detect and manipulate target RNAs. Applications include analysis of subcellular RNA localization or post-transcriptional regulation but require sequence-specificity to be readily adjustable to any target RNA. The Pumilio homology domain binds an eight nucleotide target sequence in a predictable manner allowing for rational design of variants with new specificities. We describe a high-throughput system for screening Pumilio variants based on fluorescence-activated cell sorting of E. coli. Our approach should help optimizing variants obtained from rational design regarding folding and stability or identifying new variants with alternative binding modes.

  3. Population dynamics and host reactions in young foxes following experimental infection with the minute intestinal fluke, Haplorchis pumilio

    PubMed Central

    2013-01-01

    Background Infections with fish-borne zoonotic trematodes (FZT) including the minute intestinal fluke, Haplorchis pumilio, are highly prevalent in Southeast Asia. However, little is known about the infection dynamics and clinical symptoms in the final hosts which include a range of animal species and man. We aimed to generate such information using an experimental model with H. pumilio in foxes. Method Eight commercially bred foxes were each orally infected with 2000 H. pumilio metacercariae. Another three foxes served as uninfected controls. Faecal examination for eggs was performed twice weekly. The body weight was measured, standard haematological and biochemical analysis were performed regularly. All foxes were euthanized at day 56 post infection (p.i.). Adult worms were quantified and location in the small intestine noted. Results Anorexia was observed in all infected foxes starting day 12 p.i. and lasting for approximately a week. A weight loss was noticed in the infected group in weeks 3–6 p.i. Five of eight infected foxes excreted H. pumilio eggs day 9 p.i. onwards, the remaining three started on day 13 p.i. Mean (± SD) faecal egg counts showed an initial peak at day 16–20 with a maximum of 1443 ± 1176 eggs per gram of faeces (epg), where after a stable egg output around 4–500 epg was seen. Worm burdens ranged between 116–2070 adult flukes with a mean (± SD) worm recovery of 948 ± 666. The majority of worms were found in the lower part of the jejunum. Total white blood cell and lymphocyte counts were significant lower in the infected group from first week p.i. onwards and throughout the study period. A significantly lower level of eosinophils was found in week 2 p.i. and transient anaemia was seen in week 2 and 4 p.i. Conclusion This study showed a short prepatency period, an initial peak in egg excretion, establishment of infection in all animals with predilection site in the lower jejunum and a marked but transient clinical effect of

  4. Population dynamics and host reactions in young foxes following experimental infection with the minute intestinal fluke, Haplorchis pumilio.

    PubMed

    Nissen, Sofie; Thamsborg, Stig Milan; Kania, Per Walther; Leifsson, Páll S; Dalsgaard, Anders; Johansen, Maria Vang

    2013-01-04

    Infections with fish-borne zoonotic trematodes (FZT) including the minute intestinal fluke, Haplorchis pumilio, are highly prevalent in Southeast Asia. However, little is known about the infection dynamics and clinical symptoms in the final hosts which include a range of animal species and man. We aimed to generate such information using an experimental model with H. pumilio in foxes. Eight commercially bred foxes were each orally infected with 2000 H. pumilio metacercariae. Another three foxes served as uninfected controls. Faecal examination for eggs was performed twice weekly. The body weight was measured, standard haematological and biochemical analysis were performed regularly. All foxes were euthanized at day 56 post infection (p.i.). Adult worms were quantified and location in the small intestine noted. Anorexia was observed in all infected foxes starting day 12 p.i. and lasting for approximately a week. A weight loss was noticed in the infected group in weeks 3-6 p.i. Five of eight infected foxes excreted H. pumilio eggs day 9 p.i. onwards, the remaining three started on day 13 p.i. Mean (± SD) faecal egg counts showed an initial peak at day 16-20 with a maximum of 1443 ± 1176 eggs per gram of faeces (epg), where after a stable egg output around 4-500 epg was seen. Worm burdens ranged between 116-2070 adult flukes with a mean (± SD) worm recovery of 948 ± 666. The majority of worms were found in the lower part of the jejunum. Total white blood cell and lymphocyte counts were significant lower in the infected group from first week p.i. onwards and throughout the study period. A significantly lower level of eosinophils was found in week 2 p.i. and transient anaemia was seen in week 2 and 4 p.i. This study showed a short prepatency period, an initial peak in egg excretion, establishment of infection in all animals with predilection site in the lower jejunum and a marked but transient clinical effect of the infection. The findings on egg output and

  5. Karyotypic variation in Rhinophylla pumilio Peters, 1865 and comparative analysis with representatives of two subfamilies of Phyllostomidae (Chiroptera)

    PubMed Central

    Gomes, Anderson José Baia; Nagamachi, Cleusa Yoshiko; Rodrigues, Luís Reginaldo Ribeiro; Farias, Solange Gomes; Rissino, Jorge Dores; Pieczarka, Julio Cesar

    2012-01-01

    Abstract The family Phyllostomidae belongs to the most abundant and diverse group of bats in the Neotropics with more morphological traits variation at the family level than any other group within mammals. In this work, we present data of chromosome banding (G, C and Ag-NOR) and Fluorescence In Situ Hybridization (FISH) for representatives of Rhinophylla pumilio Peters, 1865 collected in four states of Brazil (Amazonas, Bahia, Mato Grosso and Pará). Two karyomorphs were found in this species: 2n=34, FN=64 in populations from western Pará and Mato Grosso states and 2n=34, FN=62 from Amazonas, Bahia, and northeastern Pará and Marajó Island (northern). Difference in the Fundamental Number is determined by variation in the size of the Nucleolar Organizer Region (NOR) accompanied with heterochromatin on chromosomes of pair 16 or, alternatively, a pericentric inversion. The C-banding technique detected constitutive heterochromatin in the centromeric regions of all chromosomes and on the distal part of the long arm of pair 15 of specimens from all localities. FISH with a DNA telomeric probe did not show any interstitial sequence, and an 18S rDNA probe and silver staining revealed the presence of NOR in the long arm of the pair 15, associated with heterochromatin, and in the short arm of the pair 16 for all specimens. The intra-specific analysis using chromosome banding did not show any significant difference between the samples. The comparative analyses using G-banding have shown that nearly all chromosomes of Rhinophylla pumilio were conserved in the chromosome complements of Glossophaga soricina Pallas, 1766, Phyllostomus hastatus Pallas, 1767, Phyllostomus discolor Wagner, 1843 and Mimon crenulatum Geoffroy, 1801, with a single chromosomal pair unique to Rhinophylla pumilio (pair 15). However, two chromosomes of Mimon crenulatum are polymorphic for two independent pericentric inversions. The karyotype with 2n=34, NF=62 is probably the ancestral one for the other

  6. Regulation of synaptic Pumilio function by an aggregation-prone domain

    PubMed Central

    Salazar, Anna M.; Silverman, Edward J.; Menon, Kaushiki P.; Zinn, Kai

    2010-01-01

    We identified Pumilio (Pum), a Drosophila translational repressor, in a computational search for metazoan proteins whose activities might be regulated by assembly into ordered aggregates. The search algorithm was based on evolutionary sequence conservation patterns observed for yeast prion proteins, which contain aggregation-prone glutamine/asparagine (Q/N)-rich domains attached to functional domains of normal amino acid composition. We examined aggregation of Pum and its nematode ortholog PUF-9 by expression in yeast. A domain of Pum containing the Q/N-rich sequence, denoted as NQ1, the entire Pum N-terminus, and the complete PUF-9 protein localize to macroscopic aggregates (foci) in yeast. NQ1 and PUF-9 can generate the yeast Pin+ trait, which is transmitted by a heritable aggregate. NQ1 also assembles into amyloid fibrils in vitro. In Drosophila, Pum regulates postsynaptic translation at neuromuscular junctions (NMJs). To assess whether NQ1 affects synaptic Pum activity in vivo, we expressed it in muscles. We found that it negatively regulates endogenous Pum, producing gene dosage-dependent pum loss-of-function NMJ phenotypes. NQ1 coexpression also suppresses lethality and NMJ phenotypes caused by overexpression of Pum in muscles. The Q/N block of NQ1 is required for these phenotypic effects. Negative regulation of Pum by NQ1 might be explained by formation of inactive aggregates, but we have been unable to demonstrate that NQ1 aggregates in Drosophila. NQ1 could also regulate Pum by a “dominant-negative” effect, in which it would block Q/N-mediated interactions of Pum with itself or with cofactors required for translational repression. PMID:20071514

  7. Effect of ectomycorrhizal colonization and drought on reactive oxygen species metabolism of Nothofagus dombeyi roots.

    PubMed

    Alvarez, Maricel; Huygens, Dries; Fernandez, Carlos; Gacitúa, Yessy; Olivares, Erick; Saavedra, Isabel; Alberdi, Miren; Valenzuela, Eduardo

    2009-08-01

    Infection with ectomycorrhizal fungi can increase the ability of plants to resist drought stress through morphophysiological and biochemical mechanisms. However, the metabolism of antioxidative enzyme activities in the ectomycorrhizal symbiosis remains poorly understood. This study investigated biomass production, reactive oxygen metabolism (hydrogen peroxide and malondialdehyde concentration) and antioxidant enzyme activity (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) in pure cultures of the ectomycorrhizal fungi Descolea antartica Sing. and Pisolithus tinctorius (Pers.) Coker & Couch, and non-mycorrhizal and mycorrhizal roots of Nothofagus dombeyi (Mirb.) roots under well-watered conditions and drought conditions (DC). The studied ectomycorrhizal fungi regulated their antioxidative enzyme metabolism differentially in response to drought, resulting in cellular damage in D. antartica but not in P. tinctorius. Ectomycorrhizal inoculation and water treatment had a significant effect on all parameters studied, including relative water content of the plant. As such, N. dombeyi plants in symbiosis experienced a lower oxidative stress effect than non-mycorrhizal plants under DC. Additionally, ectomycorrhizal N. dombeyi roots showed a greater antioxidant enzyme activity relative to non-mycorrhizal roots, an effect which was further expressed under DC. The association between the non-specific P. tinctorius and N. dombeyi had a more effective reactive oxygen species (ROS) metabolism than the specific D. antartica-N. dombeyi symbiosis. We conclude that the combination of effective ROS prevention and ROS detoxification by ectomycorrhizal plants resulted in reduced cellular damage and increased plant growth relative to non-mycorrhizal plants under drought.

  8. Surface-bound phosphatase activity in living hyphae of ectomycorrhizal fungi of Nothofagus obliqua.

    PubMed

    Alvarez, Maricel; Godoy, Roberto; Heyser, Wolfgang; Härtel, Steffen

    2004-01-01

    We determined the location and the activity of surface-bound phosphomonoesterase (SBP) of five ectomycorrhizal (EM) fungi of Nothofagus oblique. EM fungal mycelium of Paxillus involutus, Austropaxillus boletinoides, Descolea antartica, Cenococcum geophilum and Pisolithus tinctorius was grown in media with varying concentrations of dissolved phosphorus. SBP activity was detected at different pH values (3-7) under each growth regimen. SBP activity was assessed using a colorimetric method based on the hydrolysis of p-nitrophenyl phosphate (pNPP) to p-nitrophenol phosphate (pNP) + P. A new technique involving confocal laser-scanning microscopy (LSM) was used to locate and quantify SBP activity on the hyphal surface. EM fungi showed two fundamentally different patterns of SBP activity in relation to varying environmental conditions (P-concentrations and pH). In the cases of D. antartica, A. boletinoides and C. geophilum, changes in SBP activity were induced primarily by changes in the number of SBP-active centers on the hyphae. In the cases of P. tinctorius and P. involutus, the number of SBP-active centers per μm hyphal length changed much less than the intensity of the SBP-active centers on the hyphae. Our findings not only contribute to the discussion about the role of SBP-active centers in EM fungi but also introduce LSM as a valuable method for studying EM fungi.

  9. Chemical and Antioxidant Properties of Wild Edible Mushrooms from Native Nothofagus spp. Forest, Argentina.

    PubMed

    Toledo, Carolina V; Barroetaveña, Carolina; Fernandes, Ângela; Barros, Lillian; Ferreira, Isabel C F R

    2016-09-08

    This study addresses issues regarding chemical and bioactive properties of nine wild edible mushrooms from native Nothofagus forest from Patagonia, Argentina. Macronutrients, sugars, fatty acids, tocopherols, organic acids, phenolic compounds and antioxidant properties were determined. Protein was found in high levels and varied between 3.35 g/100 g dw in Cyttaria hariotii and 22.29 g/100 g dw in Lepista nuda. All of them presented mannitol and trehalose as main sugars. Mannitol was significantly higher in Ramaria patagonica, although absent in Fistulina endoxantha, whereas trehalose predominated in Aleurodiscus vitellinus, Hydropus dusenii, Cortinarius magellanicus, C. hariotii, Grifola gargal and L. nuda, ranging from 1.15 to 10.26 g/100 g dw; it was absent in R. patagonica. The major fatty acid found was linoleic acid, followed by oleic acid and palmitic acid. All species presented oxalic and fumaric acids, while some also had malic, quinic and citric acids. Tocopherols composition was variable. Cortinarius magellanicus presented significantly higher contents of both α-tocopherol and β-tocopherol. R. patagonica presented the best results in all the antioxidant activity assays (EC50 values ≤ 1 mg/mL) and the highest content of phenolic compounds presenting gallic, p-hydroxybenzoic, p-coumaric and cinnamic acids. This study constitutes the first report on chemical composition and nutritional value of most of these edible mushroom species. Furthermore, it provides important information necessary to characterize and define the use of these species as gastronomic delicacies, functional foods and sources of bioactive compounds.

  10. Water supply and demand remain balanced during leaf acclimation of Nothofagus cunninghamii trees.

    PubMed

    Brodribb, Timothy J; Jordan, Gregory J

    2011-10-01

    Higher leaf vein density (D(vein) ) enables higher rates of photosynthesis because enhanced water transport allows higher leaf conductances to CO(2) and water. If the total cost of leaf venation rises in proportion to the density of minor veins, the most efficient investment in leaf xylem relative to photosynthetic gain should occur when the water transport capacity of the leaf (determined by D(vein) ) matches potential transpirational demand (determined by stomatal size and density). We tested whether environmental plasticity in stomatal density (D(stomata) ) and D(vein) were linked in the evergreen tree Nothofagus cunninghamii to achieve a balance between liquid and gas phase water conductances. Two sources of variation were examined; within-tree light acclimation, and differences in sun leaves among plants from ecologically diverse populations. Strong, linear correlations between D(vein) and D(stomata) were found at all levels of comparison. The correlations between liquid- and vapour-phase conductances implied by these patterns of leaf anatomy were confirmed by direct measurement of leaf conductance in sun and shade foliage of an individual tree. • Our results provide strong evidence that the development of veins and stomata are coordinated so that photosynthetic yield is optimized relative to carbon investment in leaf venation.

  11. The response of leaf morphology to irradiance depends on altitude of origin in Nothofagus cunninghamii.

    PubMed

    Hovenden, Mark J; Vander Schoor, Jacqueline K

    2006-01-01

    Leaf morphology varies reliably with increasing altitude in many species, and this is generally considered to be related to temperature. Changes in irradiance with elevation may confound any relationships between a morphological character and altitude, particularly if altitude of origin affects the response to irradiance. Here we describe the interaction between irradiance and altitude of origin on leaf morphology of Southern beech, Nothofagus cunninghamii. Cuttings from each of four altitudes were grown in a glasshouse under full sunlight or 50% shade, and leaf morphology was related to irradiance, altitude of origin and accession. There was a significant interaction between irradiance and altitude of origin for leaf length, width, thickness, area, weight, specific leaf area and stomatal density. There was no effect of altitude on leaf length to width ratio or stomatal index, nor was there an interaction between irradiance and altitude of origin for these variables. These results show that the altitude of origin of a plant has an overriding impact on the leaf morphological response to irradiance. This must be considered in climatic reconstructions.

  12. Specific and modular binding code for cytosine recognition in Pumilio/FBF (PUF) RNA-binding domains.

    PubMed

    Dong, Shuyun; Wang, Yang; Cassidy-Amstutz, Caleb; Lu, Gang; Bigler, Rebecca; Jezyk, Mark R; Li, Chunhua; Hall, Traci M Tanaka; Wang, Zefeng

    2011-07-29

    Pumilio/fem-3 mRNA-binding factor (PUF) proteins possess a recognition code for bases A, U, and G, allowing designed RNA sequence specificity of their modular Pumilio (PUM) repeats. However, recognition side chains in a PUM repeat for cytosine are unknown. Here we report identification of a cytosine-recognition code by screening random amino acid combinations at conserved RNA recognition positions using a yeast three-hybrid system. This C-recognition code is specific and modular as specificity can be transferred to different positions in the RNA recognition sequence. A crystal structure of a modified PUF domain reveals specific contacts between an arginine side chain and the cytosine base. We applied the C-recognition code to design PUF domains that recognize targets with multiple cytosines and to generate engineered splicing factors that modulate alternative splicing. Finally, we identified a divergent yeast PUF protein, Nop9p, that may recognize natural target RNAs with cytosine. This work deepens our understanding of natural PUF protein target recognition and expands the ability to engineer PUF domains to recognize any RNA sequence.

  13. A divergent Pumilio repeat protein family for pre-rRNA processing and mRNA localization

    DOE PAGES

    Qiu, Chen; McCann, Kathleen L.; Wine, Robert N.; ...

    2014-12-15

    Pumilio/feminization of XX and XO animals (fem)-3 mRNA-binding factor (PUF) proteins bind sequence specifically to mRNA targets using a single-stranded RNA-binding domain comprising eight Pumilio (PUM) repeats. PUM repeats have now been identified in proteins that function in pre-rRNA processing, including human Puf-A and yeast Puf6. This is a role not previously ascribed to PUF proteins. In this paper we present crystal structures of human Puf-A that reveal a class of nucleic acid-binding proteins with 11 PUM repeats arranged in an “L”-like shape. In contrast to classical PUF proteins, Puf-A forms sequence-independent interactions with DNA or RNA, mediated by conservedmore » basic residues. We demonstrate that equivalent basic residues in yeast Puf6 are important for RNA binding, pre-rRNA processing, and mRNA localization. Finally, PUM repeats can be assembled into alternative folds that bind to structured nucleic acids in addition to forming canonical eight-repeat crescent-shaped RNA-binding domains found in classical PUF proteins.« less

  14. Specific and Modular Binding Code for Cytosine Recognition in Pumilio/FBF (PUF) RNA-binding Domains

    SciTech Connect

    Dong, Shuyun; Wang, Yang; Cassidy-Amstutz, Caleb; Lu, Gang; Bigler, Rebecca; Jezyk, Mark R.; Li, Chunhua; Tanaka Hall, Traci M.; Wang, Zefeng

    2011-10-28

    Pumilio/fem-3 mRNA-binding factor (PUF) proteins possess a recognition code for bases A, U, and G, allowing designed RNA sequence specificity of their modular Pumilio (PUM) repeats. However, recognition side chains in a PUM repeat for cytosine are unknown. Here we report identification of a cytosine-recognition code by screening random amino acid combinations at conserved RNA recognition positions using a yeast three-hybrid system. This C-recognition code is specific and modular as specificity can be transferred to different positions in the RNA recognition sequence. A crystal structure of a modified PUF domain reveals specific contacts between an arginine side chain and the cytosine base. We applied the C-recognition code to design PUF domains that recognize targets with multiple cytosines and to generate engineered splicing factors that modulate alternative splicing. Finally, we identified a divergent yeast PUF protein, Nop9p, that may recognize natural target RNAs with cytosine. This work deepens our understanding of natural PUF protein target recognition and expands the ability to engineer PUF domains to recognize any RNA sequence.

  15. A divergent Pumilio repeat protein family for pre-rRNA processing and mRNA localization

    SciTech Connect

    Qiu, Chen; McCann, Kathleen L.; Wine, Robert N.; Baserga, Susan J.; Hall, Traci M. Tanaka

    2014-12-15

    Pumilio/feminization of XX and XO animals (fem)-3 mRNA-binding factor (PUF) proteins bind sequence specifically to mRNA targets using a single-stranded RNA-binding domain comprising eight Pumilio (PUM) repeats. PUM repeats have now been identified in proteins that function in pre-rRNA processing, including human Puf-A and yeast Puf6. This is a role not previously ascribed to PUF proteins. In this paper we present crystal structures of human Puf-A that reveal a class of nucleic acid-binding proteins with 11 PUM repeats arranged in an “L”-like shape. In contrast to classical PUF proteins, Puf-A forms sequence-independent interactions with DNA or RNA, mediated by conserved basic residues. We demonstrate that equivalent basic residues in yeast Puf6 are important for RNA binding, pre-rRNA processing, and mRNA localization. Finally, PUM repeats can be assembled into alternative folds that bind to structured nucleic acids in addition to forming canonical eight-repeat crescent-shaped RNA-binding domains found in classical PUF proteins.

  16. Evidence of maternal provisioning of alkaloid-based chemical defenses in the strawberry poison frog Oophaga pumilio.

    PubMed

    Stynoski, Jennifer L; Torres-Mendoza, Yaritbel; Sasa-Marin, Mahmood; Saporito, Ralph A

    2014-03-01

    Many organisms use chemical defenses to reduce predation risk. Aposematic dendrobatid frogs sequester alkaloid-based chemical defenses from a diet of arthropods, but research on these defenses has been limited to adults. Herein, we investigate chemical defense across development in a dendrobatid frog, Oophaga pumilio. This species displays complex parental care: at hatching, mothers transport tadpoles to phytotelmata, and then return to supply them with an obligate diet of nutritive eggs for about six weeks. We collected eggs, tadpoles, juveniles, and adults of O. pumilio, and detected alkaloids in all life stages. The quantity and number of alkaloids increased with frog and tadpole size. We did not detect alkaloids in the earliest stage of tadpoles, but alkaloids were detected as trace quantities in nutritive eggs and as small quantities in ovarian eggs. Tadpoles hand-reared with eggs of an alkaloid-free heterospecific frog did not contain alkaloids. Alkaloids that are sequestered from terrestrial arthropods were detected in both adults and phytotelm-dwelling tadpoles that feed solely on nutritive eggs, suggesting that this frog may be the first animal known to actively provision post-hatch offspring with chemical defenses. Finally, we provide experimental evidence that maternally derived alkaloids deter predation of tadpoles by a predatory arthropod.

  17. Ectomycorrhizas naturally established in Nothofagus nervosa seedlings under different cultivation practices in a forest nursery.

    PubMed

    Fernández, Natalia V; Marchelli, Paula; Fontenla, Sonia B

    2013-10-01

    Mycorrhizas are mutualistic associations between soil fungi and plant roots which usually improve water and nutrient uptake, influencing plant fitness. Nothofagus nervosa (Raulí) is an ecologically and economically important species of South American temperate forests. Since this native tree species yields valuable timber, it was overexploited and its natural distribution area was critically reduced, so it is currently included in domestication and conservation programs. Among the factors that should be considered in these programs are the ectomycorrhizas (EcM), which would be important for the successful establishment and survival of outplanted seedlings. The aim of this work was to analyze the abundance and diversity of EcM in N. nervosa nursery-cultivated seedlings assessed by morphotyping, fungal isolation, and DNA sequencing. Arbuscular mycorrhiza (AM) occurrence was also studied. A 2-year trial was conducted following the cultivation conditions used for domestication programs. Seedlings were cultivated under two different cultivation practices (greenhouse and nursery soil) without artificial inoculation of mycorrhizal fungi. Seedlings' roots were examined at different times. It was observed that they developed EcM between 6 and 12 months after germination and AMs were not detected in any plant. The most abundant ectomycorrhizal fungi present in seedlings' roots were Tomentella ellisii (Basidiomycota) and an unidentified fungus named Ascomicetous EcM sp. 1. Abundance and diversity of EcM varied between the two cultivation techniques analyzed in this study, since seedlings that continued growing in the greenhouse had higher colonization values, but those transplanted to the nursery soil were colonized by a higher diversity of fungal taxa.

  18. Size-Specific Tree Mortality Varies with Neighbourhood Crowding and Disturbance in a Montane Nothofagus Forest

    PubMed Central

    Hurst, Jennifer M.; Allen, Robert B.; Coomes, David A.; Duncan, Richard P.

    2011-01-01

    Tree mortality is a fundamental process governing forest dynamics, but understanding tree mortality patterns is challenging because large, long-term datasets are required. Describing size-specific mortality patterns can be especially difficult, due to few trees in larger size classes. We used permanent plot data from Nothofagus solandri var. cliffortioides (mountain beech) forest on the eastern slopes of the Southern Alps, New Zealand, where the fates of trees on 250 plots of 0.04 ha were followed, to examine: (1) patterns of size-specific mortality over three consecutive periods spanning 30 years, each characterised by different disturbance, and (2) the strength and direction of neighbourhood crowding effects on size-specific mortality rates. We found that the size-specific mortality function was U-shaped over the 30-year period as well as within two shorter periods characterised by small-scale pinhole beetle and windthrow disturbance. During a third period, characterised by earthquake disturbance, tree mortality was less size dependent. Small trees (<20 cm in diameter) were more likely to die, in all three periods, if surrounded by a high basal area of larger neighbours, suggesting that size-asymmetric competition for light was a major cause of mortality. In contrast, large trees (≥20 cm in diameter) were more likely to die in the first period if they had few neighbours, indicating that positive crowding effects were sometimes important for survival of large trees. Overall our results suggest that temporal variability in size-specific mortality patterns, and positive interactions between large trees, may sometimes need to be incorporated into models of forest dynamics. PMID:22046327

  19. Solar radiation transmission in and around canopy gaps in an uneven-aged Nothofagus betuloides forest.

    PubMed

    Promis, Alvaro; Schindler, Dirk; Reif, Albert; Cruz, Gustavo

    2009-07-01

    The transmission of direct, diffuse and global solar radiation in and around canopy gaps occurring in an uneven-aged, evergreen Nothofagus betuloides forest during the growing season (October 2006-March 2007) was estimated by means of hemispherical photographs. The transmission of solar radiation into the forest was affected not only by a high level of horizontal and vertical heterogeneity of the forest canopy, but also by low angles of the sun's path. The below-canopy direct solar radiation appeared to be variable in space and time. On average, the highest amount of transmitted direct solar radiation was estimated below the undisturbed canopy at the southeast of the gap centre. The transmitted diffuse and global solar radiation above the forest floor exhibited lower variability and, on average, both were higher at the centre of the canopy gaps. Canopy structure and stand parameters were also measured to explain the variation in the below-canopy solar radiation in the forest. The model that best fit the transmitted below-canopy direct solar radiation was a growth model, using plant area index with an ellipsoidal angle distribution as the independent variable (R (2) = 0.263). Both diffuse and global solar radiation were very sensitive to canopy openness, and for both cases a quadratic model provided the best fit for these data (R (2) = 0.963 and 0.833, respectively). As much as 75% and 73% of the variation in the diffuse and global solar radiation, respectively, were explained by a combination of stand parameters, namely basal area, crown projection, crown volume, stem volume, and average equivalent crown radius.

  20. PUMILIO-2 Is Involved in the Positive Regulation of Cellular Proliferation in Human Adipose-Derived Stem Cells

    PubMed Central

    Shigunov, Patrícia; Kuligovski, Crisciele; de Aguiar, Alessandra Melo; Rebelatto, Carmen K.; Moutinho, José A.; Brofman, Paulo S.; Krieger, Marco A.; Goldenberg, Samuel; Munroe, David; Correa, Alejandro

    2012-01-01

    Stem cells can either differentiate into more specialized cells or undergo self-renewal. Several lines of evidence from different organisms suggest that these processes depend on the post-transcriptional regulation of gene expression. The presence of the PUF [Pumilio/FBF (fem-3 binding factor)] domain defines a conserved family of RNA binding proteins involved in repressing gene expression. It has been suggested that a conserved function of PUF proteins is to repress differentiation and sustain the mitotic proliferation of stem cells. In humans, Pumilio-2 (PUM2) is expressed in embryonic stem cells and adult germ cells. Here we show that PUM2 is expressed in a subpopulation of adipose-derived stem cell (ASC) cultures, with a granular pattern of staining in the cytoplasm. Protein levels of PUM2 showed no changes during the differentiation of ASCs into adipocytes. Moreover, RNAi knockdown of pum2 did not alter the rate of adipogenic differentiation compared with wild-type control cells. A ribonomic approach was used to identify PUM2-associated mRNAs. Microarray analysis showed that PUM2-bound mRNAs are part of gene networks involved in cell proliferation and gene expression control. We studied pum2 expression in cell cultures with low or very high levels of proliferation and found that changes in pum2 production were dependent on the proliferation status of the cell. Transient knockdown of pum2 expression by RNAi impaired proliferation of ASCs in vitro. Our results suggest that PUM2 does not repress differentiation of ASCs but rather is involved in the positive control of ASCs division and proliferation. PMID:21649561

  1. Testing the impact of calibration on molecular divergence times using a fossil-rich group: the case of Nothofagus (Fagales).

    PubMed

    Sauquet, Hervé; Ho, Simon Y W; Gandolfo, Maria A; Jordan, Gregory J; Wilf, Peter; Cantrill, David J; Bayly, Michael J; Bromham, Lindell; Brown, Gillian K; Carpenter, Raymond J; Lee, Daphne M; Murphy, Daniel J; Sniderman, J M Kale; Udovicic, Frank

    2012-03-01

    Although temporal calibration is widely recognized as critical for obtaining accurate divergence-time estimates using molecular dating methods, few studies have evaluated the variation resulting from different calibration strategies. Depending on the information available, researchers have often used primary calibrations from the fossil record or secondary calibrations from previous molecular dating studies. In analyses of flowering plants, primary calibration data can be obtained from macro- and mesofossils (e.g., leaves, flowers, and fruits) or microfossils (e.g., pollen). Fossil data can vary substantially in accuracy and precision, presenting a difficult choice when selecting appropriate calibrations. Here, we test the impact of eight plausible calibration scenarios for Nothofagus (Nothofagaceae, Fagales), a plant genus with a particularly rich and well-studied fossil record. To do so, we reviewed the phylogenetic placement and geochronology of 38 fossil taxa of Nothofagus and other Fagales, and we identified minimum age constraints for up to 18 nodes of the phylogeny of Fagales. Molecular dating analyses were conducted for each scenario using maximum likelihood (RAxML + r8s) and Bayesian (BEAST) approaches on sequence data from six regions of the chloroplast and nuclear genomes. Using either ingroup or outgroup constraints, or both, led to similar age estimates, except near strongly influential calibration nodes. Using "early but risky" fossil constraints in addition to "safe but late" constraints, or using assumptions of vicariance instead of fossil constraints, led to older age estimates. In contrast, using secondary calibration points yielded drastically younger age estimates. This empirical study highlights the critical influence of calibration on molecular dating analyses. Even in a best-case situation, with many thoroughly vetted fossils available, substantial uncertainties can remain in the estimates of divergence times. For example, our estimates for

  2. Biome specificity of distinct genetic lineages within the four-striped mouse Rhabdomys pumilio (Rodentia: Muridae) from southern Africa with implications for taxonomy.

    PubMed

    du Toit, Nina; van Vuuren, Bettine Jansen; Matthee, Sonja; Matthee, Conrad A

    2012-10-01

    Within southern Africa, a link between past climatic changes and faunal diversification has been hypothesized for a diversity of taxa. To test the hypothesis that evolutionary divergences may be correlated to vegetation changes (induced by changes in climate), we selected the widely distributed four-striped mouse, Rhabdomys, as a model. Two species are currently recognized, the mesic-adapted R. dilectus and arid-adapted R. pumilio. However, the morphology-based taxonomy and the distribution boundaries of previously described subspecies remain poorly defined. The current study, which spans seven biomes, focuses on the spatial genetic structure of the arid-adapted R. pumilio (521 specimens from 31 localities), but also includes limited sampling of the mesic-adapted R. dilectus (33 specimens from 10 localities) to act as a reference for interspecific variation within the genus. The mitochondrial COI gene and four nuclear introns (Eef1a1, MGF, SPTBN1, Bfib7) were used for the construction of gene trees. Mitochondrial DNA analyses indicate that Rhabdomys consists of four reciprocally monophyletic, geographically structured clades, with three distinct lineages present within the arid-adapted R. pumilio. These monophyletic lineages differ by at least 7.9% (±0.3) and these results are partly confirmed by a multilocus network of the combined nuclear intron dataset. Ecological niche modeling in MaxEnt supports a strong correlation between regional biomes and the distribution of distinct evolutionary lineages of Rhabdomys. A Bayesian relaxed molecular clock suggests that the geographic clades diverged between 3.09 and 4.30Ma, supporting the hypothesis that the radiation within the genus coincides with paleoclimatic changes (and the establishment of the biomes) characterizing the Miocene-Pliocene boundary. Marked genetic divergence at the mitochondrial DNA level, coupled with strong nuclear and mtDNA signals of non-monophyly of R. pumilio, support the notion that a taxonomic

  3. Preformation and distribution of staminate and pistillate flowers in growth units of Nothofagus alpina and N. obliqua (Nothofagaceae)

    PubMed Central

    Puntieri, Javier G.; Grosfeld, Javier E.; Heuret, Patrick

    2009-01-01

    Background and Aims The distribution and differentiation times of flowers in monoecious wind-pollinated plants are fundamental for the understanding of their mating patterns and evolution. Two closely related South American Nothofagus species were compared with regard to the differentiation times and positions of staminate and pistillate flowers along their parent growth units (GUs) by quantitative means. Methods Two samples of GUs that had extended in the 2004–2005 growing season were taken in 2005 and 2006 from trees in the Lanín National Park, Patagonia, Argentina. For the first sample, axillary buds of the parent GUs were dissected and the leaf, bud and flower primordia of these buds were identified. The second sample included all branches derived from the parent GUs in the 2005–2006 growing season. Key Results Both species developed flowering GUs with staminate and/or pistillate flowers; GUs with both flower types were the most common. The position of staminate flowers along GUs was similar between species and close to the proximal end of the GUs. Pistillate flowers were developed more distally along the GUs in N. alpina than in N. obliqua. In N. alpina, the nodes bearing staminate and pistillate flowers were separated by one to several nodes with axillary buds, something not observed in N. obliqua. Markovian models supported this between-species difference. Flowering GUs, including all of their leaves and flowers were entirely preformed in the winter buds. Conclusions Staminate and pistillate flowers of N. alpina and N. obliqua are differentiated at precise locations on GUs in the growing season preceding that of their antheses. The differences between N. alpina and N. obliqua (and other South American Nothofagus species) regarding flower distribution might relate to the time of anthesis of each flower type and, in turn, to the probabilities of self-pollination at the GU level. PMID:19033286

  4. The ribosomal transcription units of Haplorchis pumilio and H. taichui and the use of 28S rDNA sequences for phylogenetic identification of common heterophyids in Vietnam.

    PubMed

    Le, Thanh Hoa; Nguyen, Khue Thi; Nguyen, Nga Thi Bich; Doan, Huong Thi Thanh; Dung, Do Trung; Blair, David

    2017-01-09

    Heterophyidiasis is now a major public health threat in many tropical countries. Species in the trematode family Heterophyidae infecting humans include Centrocestus formosanus, Haplorchis pumilio, H. taichui, H. yokogawai, Procerovum varium and Stellantchasmus falcatus. For molecular phylogenetic and systematic studies on trematodes, we need more prospective markers for taxonomic identification and classification. This study provides near-complete ribosomal transcription units (rTU) from Haplorchis pumilio and H. taichui and demonstrates the use of 28S rDNA sequences for identification and phylogenetic analysis. The near-complete ribosomal transcription units (rTU), consisting of 18S, ITS1, 5.8S, ITS2 and 28S rRNA genes and spacers, from H. pumilio and H. taichui from human hosts in Vietnam, were determined and annotated. Sequence analysis revealed tandem repetitive elements in ITS1 in H. pumilio and in ITS2 in H. taichui. A phylogenetic tree inferred from 28S rDNA sequences of 40 trematode strains/species, including 14 Vietnamese heterophyid individuals, clearly confirmed the status of each of the Vietnamese species: Centrocestus formosanus, Haplorchis pumilio, H. taichui, H. yokogawai, Procerovum varium and Stellantchasmus falcatus. However, the family Heterophyidae was clearly not monophyletic, with some genera apparently allied with other families within the superfamily Opisthorchioidea (i.e. Cryptogonimidae and Opisthorchiidae). These families and their constituent genera require substantial re-evaluation using a combination of morphological and molecular data. Our new molecular data will assist in such studies. The 28S rDNA sequences are conserved among individuals within a species but varied between genera. Based on analysis of 40 28S rDNA sequences representing 19 species in the superfamily Opisthorchioidea and an outgroup taxon (Alaria alata, family Diplostomidae), six common human pathogenic heterophyids were identified and clearly resolved. The

  5. Seasonal variation in attention and spatial performance in a wild population of the African striped mouse (Rhabdomys pumilio).

    PubMed

    Maille, Audrey; Pillay, Neville; Schradin, Carsten

    2015-11-01

    Cognitive flexibility describes the reversible changes of cognition in response to environmental changes. Although various environmental factors such as temperature, photoperiod and rainfall change seasonally, seasonal variation in cognitive performance has been reported in merely a few birds and mammals. We assessed whether cognitive performance in a wild population of African striped mice Rhabdomys pumilio, from the Succulent Karoo semidesert of South Africa, differed between summer and winter. In order to measure cognitive performance, striped mice were trapped in the field, tested under laboratory conditions at our research station and returned to the field within 5 h. We measured attention and spatial memory using the standardized orientation response test and the Barnes maze test. Males tested during summer oriented faster toward a predator-stimulus but made more errors and took longer to locate a shelter than males tested during winter. In contrast, females' performance did not differ between the two seasons. We discuss how the faster orientation in males during winter might be the consequence of lower temperatures and/or prolonged food restriction. We suggest that the enhancement of spatial performance during winter might be due to a greater motivation for future dispersal in male striped mice, as spring represents the breeding season.

  6. Drosophila Nanos acts as a molecular clamp that modulates the RNA-binding and repression activities of Pumilio

    PubMed Central

    Weidmann, Chase A; Qiu, Chen; Arvola, René M; Lou, Tzu-Fang; Killingsworth, Jordan; Campbell, Zachary T; Tanaka Hall, Traci M; Goldstrohm, Aaron C

    2016-01-01

    Collaboration among the multitude of RNA-binding proteins (RBPs) is ubiquitous, yet our understanding of these key regulatory complexes has been limited to single RBPs. We investigated combinatorial translational regulation by Drosophila Pumilio (Pum) and Nanos (Nos), which control development, fertility, and neuronal functions. Our results show how the specificity of one RBP (Pum) is modulated by cooperative RNA recognition with a second RBP (Nos) to synergistically repress mRNAs. Crystal structures of Nos-Pum-RNA complexes reveal that Nos embraces Pum and RNA, contributes sequence-specific contacts, and increases Pum RNA-binding affinity. Nos shifts the recognition sequence and promotes repression complex formation on mRNAs that are not stably bound by Pum alone, explaining the preponderance of sub-optimal Pum sites regulated in vivo. Our results illuminate the molecular mechanism of a regulatory switch controlling crucial gene expression programs, and provide a framework for understanding how the partnering of RBPs evokes changes in binding specificity that underlie regulatory network dynamics. DOI: http://dx.doi.org/10.7554/eLife.17096.001 PMID:27482653

  7. Pumilio1 Haploinsufficiency Leads to SCA1-like Neurodegeneration by Increasing Wild-Type Ataxin1 Levels

    PubMed Central

    Gennarino, Vincenzo A.; Singh, Ravi K.; White, Joshua J.; De Maio, Antonia; Han, Kihoon; Kim, Ji-Yoen; Jafar-Nejad, Paymaan; di Ronza, Alberto; Kang, Hyojin; Sayegh, Layal S.; Cooper, Thomas A.; Orr, Harry T.; Sillitoe, Roy V.; Zoghbi, Huda Y.

    2015-01-01

    SUMMARY Spinocerebellar ataxia type 1 (SCA1) is a paradigmatic neurodegenerative proteinopathy, in which a mutant protein (in this case, ATAXIN1) accumulates in neurons and exerts toxicity; in SCA1 this process causes progressive deterioration of motor coordination. Seeking to understand how post-translational modification of ATAXIN1 levels influences disease, we discovered that the RNA-binding protein PUMILIO1 (PUM1) not only directly regulates ATAXIN1 but that it also plays an unexpectedly important role in neuronal function. Loss of Pum1 caused progressive motor dysfunction and SCA1-like neurodegeneration with motor impairment, primarily by increasing Ataxin1 levels. Breeding Pum1+/− mice to SCA1 mice (Atxn1154Q/+) exacerbated disease progression, whereas breeding them to Atxn1+/− mice normalized Ataxin1 levels and largely rescued the Pum1+/− phenotype. Thus, both increased wild-type ATAXIN1 levels and PUM1 haploinsufficiency could contribute to human neurodegeneration. These results demonstrate the importance of studying post-transcriptional regulation of disease-driving proteins to reveal factors underlying neurodegenerative disease. PMID:25768905

  8. Reduced Pumilio-2 expression in patients with temporal lobe epilepsy and in the lithium-pilocarpine induced epilepsy rat model.

    PubMed

    Wu, Xu-Ling; Huang, Hao; Huang, Yun-Yi; Yuan, Jin-Xian; Zhou, Xin; Chen, Yang-Mei

    2015-09-01

    Drosophila Pumilio (Pum), a homolog of mammalian Pum2, plays an important role in translational regulation in the central nervous system (CNS), particularly for dendrite outgrowth and neuronal excitability. We investigated the expression pattern and cellular distribution of Pum2 in patients with drug-refractory temporal lobe epilepsy (TLE) and rats with lithium chloride-pilocarpine-induced epilepsy. Real-time quantitative PCR (RT-qPCR), Western blot, immunohistochemistry, and double-labeled immunofluorescence were utilized to determine the expression level and distribution of Pum2 in temporal neocortex tissues from patients with intractable TLE (n=20) and patients with severe head trauma (n=20) in addition to the hippocampus and adjacent cortex of rats with lithium chloride-pilocarpine-induced TLE and controls. Pum2 was expressed in the cell bodies and dendrites of neurons but did not colocalize with glial fibrillary acidic protein-positive astrocytes or propidium iodide (PI) in nuclei. The expression of Pum2 was significantly reduced in patients and rats with TLE in comparison to controls (P<0.05). Pum2 expression was less in patients with TLE and a rodent model of epilepsy, suggesting that decreased expression of Pum2 may be involved in the pathogenesis of TLE. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Drosophila Nanos acts as a molecular clamp that modulates the RNA-binding and repression activities of Pumilio

    DOE PAGES

    Weidmann, Chase A.; Qiu, Chen; Arvola, René M.; ...

    2016-08-02

    Collaboration among the multitude of RNA-binding proteins (RBPs) is ubiquitous, yet our understanding of these key regulatory complexes has been limited to single RBPs. We investigated combinatorial translational regulation by Drosophila Pumilio (Pum) and Nanos (Nos), which control development, fertility, and neuronal functions. Our results show how the specificity of one RBP (Pum) is modulated by cooperative RNA recognition with a second RBP (Nos) to synergistically repress mRNAs. Crystal structures of Nos-Pum-RNA complexes reveal that Nos embraces Pum and RNA, contributes sequence-specific contacts, and increases Pum RNA-binding affinity. Nos shifts the recognition sequence and promotes repression complex formation onmore » mRNAs that are not stably bound by Pum alone, explaining the preponderance of sub-optimal Pum sites regulated in vivo . Our results illuminate the molecular mechanism of a regulatory switch controlling crucial gene expression programs, and provide a framework for understanding how the partnering of RBPs evokes changes in binding specificity that underlie regulatory network dynamics.« less

  10. Seizure control through genetic and pharmacological manipulation of Pumilio in Drosophila: a key component of neuronal homeostasis

    PubMed Central

    Lin, Wei-Hsiang; Giachello, Carlo N. G.

    2017-01-01

    ABSTRACT Epilepsy is a significant disorder for which approximately one-third of patients do not respond to drug treatments. Next-generation drugs, which interact with novel targets, are required to provide a better clinical outcome for these individuals. To identify potential novel targets for antiepileptic drug (AED) design, we used RNA sequencing to identify changes in gene transcription in two seizure models of the fruit fly Drosophila melanogaster. The first model compared gene transcription between wild type (WT) and bangsenseless1 (parabss), a gain-of-function mutant in the sole fly voltage-gated sodium channel (paralytic). The second model compared WT with WT fed the proconvulsant picrotoxin (PTX). We identified 743 genes (FDR≤1%) with significant altered expression levels that are common to both seizure models. Of these, 339 are consistently upregulated and 397 downregulated. We identify pumilio (pum) to be downregulated in both seizure models. Pum is a known homeostatic regulator of action potential firing in both flies and mammals, achieving control of neuronal firing through binding to, and regulating translation of, the mRNA transcripts of voltage-gated sodium channels (Nav). We show that maintaining expression of pum in the CNS of parabss flies is potently anticonvulsive, whereas its reduction through RNAi-mediated knockdown is proconvulsive. Using a cell-based luciferase reporter screen, we screened a repurposed chemical library and identified 12 compounds sufficient to increase activity of pum. Of these compounds, we focus on avobenzone, which significantly rescues seizure behaviour in parabss flies. The mode of action of avobenzone includes potentiation of pum expression and mirrors the ability of this homeostatic regulator to reduce the persistent voltage-gated Na+ current (INaP) in an identified neuron. This study reports a novel approach to suppress seizure and highlights the mechanisms of neuronal homeostasis as potential targets for next

  11. Alternative Polyadenylation in Triple-Negative Breast Tumors Allows NRAS and c-JUN to Bypass PUMILIO Posttranscriptional Regulation

    PubMed Central

    Miles, Wayne O.; Lembo, Antonio; Volorio, Angela; Brachtel, Elena; Tian, Bin; Sgroi, Dennis; Provero, Paolo; Dyson, Nicholas

    2017-01-01

    Alternative polyadenylation (APA) is a process that changes the posttranscriptional regulation and translation potential of mRNAs via addition or deletion of 3′ untranslated region (3′ UTR) sequences. To identify posttranscriptional-regulatory events affected by APA in breast tumors, tumor datasets were analyzed for recurrent APA events. Motif mapping of the changed 3′ UTR regions found that APA-mediated removal of Pumilio regulatory elements (PRE) was unusually common. Breast tumor subtype–specific APA profiling identified triple-negative breast tumors as having the highest levels of APA. To determine the frequency of these events, an independent cohort of triple-negative breast tumors and normal breast tissue was analyzed for APA. APA-mediated shortening of NRAS and c-JUN was seen frequently, and this correlated with changes in the expression of downstream targets. mRNA stability and luciferase assays demonstrated APA-dependent alterations in RNA and protein levels of affected candidate genes. Examination of clinical parameters of these tumors found those with APA of NRAS and c-JUN to be smaller and less proliferative, but more invasive than non-APA tumors. RT-PCR profiling identified elevated levels of polyadenylation factor CSTF3 in tumors with APA. Overexpression of CSTF3 was common in triple-negative breast cancer cell lines, and elevated CSTF3 levels were sufficient to induce APA of NRAS and c-JUN. Our results support the hypothesis that PRE-containing mRNAs are disproportionately affected by APA, primarily due to high sequence similarity in the motifs utilized by polyadenylation machinery and the PUM complex. PMID:27758885

  12. Alternative Polyadenylation in Triple-Negative Breast Tumors Allows NRAS and c-JUN to Bypass PUMILIO Posttranscriptional Regulation.

    PubMed

    Miles, Wayne O; Lembo, Antonio; Volorio, Angela; Brachtel, Elena; Tian, Bin; Sgroi, Dennis; Provero, Paolo; Dyson, Nicholas

    2016-12-15

    Alternative polyadenylation (APA) is a process that changes the posttranscriptional regulation and translation potential of mRNAs via addition or deletion of 3' untranslated region (3' UTR) sequences. To identify posttranscriptional-regulatory events affected by APA in breast tumors, tumor datasets were analyzed for recurrent APA events. Motif mapping of the changed 3' UTR regions found that APA-mediated removal of Pumilio regulatory elements (PRE) was unusually common. Breast tumor subtype-specific APA profiling identified triple-negative breast tumors as having the highest levels of APA. To determine the frequency of these events, an independent cohort of triple-negative breast tumors and normal breast tissue was analyzed for APA. APA-mediated shortening of NRAS and c-JUN was seen frequently, and this correlated with changes in the expression of downstream targets. mRNA stability and luciferase assays demonstrated APA-dependent alterations in RNA and protein levels of affected candidate genes. Examination of clinical parameters of these tumors found those with APA of NRAS and c-JUN to be smaller and less proliferative, but more invasive than non-APA tumors. RT-PCR profiling identified elevated levels of polyadenylation factor CSTF3 in tumors with APA. Overexpression of CSTF3 was common in triple-negative breast cancer cell lines, and elevated CSTF3 levels were sufficient to induce APA of NRAS and c-JUN. Our results support the hypothesis that PRE-containing mRNAs are disproportionately affected by APA, primarily due to high sequence similarity in the motifs utilized by polyadenylation machinery and the PUM complex. Cancer Res; 76(24); 7231-41. ©2016 AACR.

  13. The Pumilio-domain protein PUF6 contributes to SIDER2 retroposon-mediated mRNA decay in Leishmania.

    PubMed

    Azizi, Hiva; Dumas, Carole; Papadopoulou, Barbara

    2017-09-06

    Leishmania and other trypanosomatid protozoa lack control at the level of transcription initiation and regulate gene expression exclusively posttranscriptionally. We have reported previously that Leishmania harbors a unique class of Short Interspersed DEgenerate Retroposons (SIDERs) that are predominantly located within 3'UTRs and play a major role in posttranscriptional control. We have shown that members of the SIDER2 subfamily initiate mRNA decay through endonucleolytic cleavage within the second conserved 79-nt signature sequence of SIDER2 retroposons. Here, we have developed an optimized MS2 coat protein tethering system to capture trans-acting factor(s) regulating SIDER2-mediated mRNA decay. Tethering of the MS2 coat protein to a reporter RNA harboring two MS2 stem loop aptamers and the cognate SIDER2-containing 3'UTR in combination with immunoprecipitation and mass spectrometry analysis led to the identification of RNA-binding proteins with known functions in mRNA decay. Amongst the candidate SIDER2-interacting proteins that were individually tethered to a SIDER2 reporter RNA, the Pumilio-domain protein PUF6 was shown to enhance degradation and reduce transcript half-life. Furthermore, we showed that PUF6 binds to SIDER2 sequences that include the regulatory 79-nt signature motif, hence contributing to the mRNA decay process. Consistent with a role of PUF6 in SIDER2-mediated decay, genetic inactivation of PUF6 resulted in increased accumulation and higher stability of endogenous SIDER2-bearing transcripts. Overall, these studies provide new insights into regulated mRNA decay pathways in Leishmania controlled by SIDER2 retroposons and propose a broader role for PUF proteins in mRNA decay within eukaryotic kingdom. Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  14. Genetic Diversity in Nothofagus alessandrii (Fagaceae), an Endangered Endemic Tree Species of the Coastal Maulino Forest of Central Chile

    PubMed Central

    Torres-Díaz, Cristian; Ruiz, Eduardo; González, Fidelina; Fuentes, Glenda; Cavieres, Lohengrin A.

    2007-01-01

    Background and Aims The endemic tree Nothofagus alessandrii (Fagaceae) has been historically restricted to the coastal range of Region VII of central Chile, and its forests have been increasingly destroyed and fragmented since the end of the 19th century. In this study, the patterns of within- and among-population genetic diversity in seven fragments of this endangered narrowly endemic tree were examined. Methods Allozyme electrophoresis of seven loci of N. alessandrii was used to estimate genetic diversity, genetic structure and gene flow. Key Results High levels of genetic diversity were found as shown by mean expected heterozygosity (He = 0·182 ± 0·034), percentage of polymorphic loci (Pp = 61·2 %), mean number of alleles per locus (A = 1·8) and mean number of alleles per polymorphic locus (Ap = 2·3). Genetic differentiation was also high (GST = 0·257 and Nm = 0·7). These values are high compared with more widespread congeneric species. Conclusions Despite its endemic status and restricted geographical range N. alessandrii showed high levels of genetic diversity. The observed patterns of diversity are explained in part by historical processes and more recent human fragmentation. PMID:17513870

  15. Genetic differentiation in spite of high gene flow in the dominant rainforest tree of southeastern Australia, Nothofagus cunninghamii.

    PubMed

    Duncan, C J; Worth, J R P; Jordan, G J; Jones, R C; Vaillancourt, R E

    2016-01-01

    Nothofagus cunninghamii is a long-lived, wind-pollinated tree species that dominates the cool temperate rainforests of southeastern Australia. The species' distribution is more or less continuous in western Tasmania but is fragmented elsewhere. However, it is unknown whether this fragmentation has affected the species' genetic architecture. Thus, we examined N. cunninghamii using 12 nuclear microsatellites and 633 individuals from 18 populations spanning the species' natural range. Typical of wind-pollinated trees, there was low range-wide genetic structure (FST=0.04) consistent with significant gene flow across most of the species' range. However, gene flow was not high enough to overcome the effects of drift across some disjunctions. Victorian populations (separated from Tasmania by the 240 km wide Bass Strait) formed a genetic group distinct from Tasmanian populations, had lower diversity (mean allelic richness (Ar)=5.4 in Victoria versus 6.9 in Tasmania) and were significantly more differentiated from one another than those in Tasmania (FST=0.045 in Victoria versus 0.012 in Tasmania). Evidence for bottlenecking was found in small populations that were at least 20 km from other populations. Interestingly, we found little divergence in microsatellite markers between the extremes of genetically based morphological and physiological altitudinal clines suggesting adaptive differentiation is strongly driven by selection because it is likely to be occurring in the presence of gene flow. Even though the cool temperate rainforests of Australia are highly relictual, the species is relatively robust to population fragmentation due to high levels of genetic diversity and gene flow, especially in Tasmania.

  16. Ectomycorrhizal fungi enhance nitrogen and phosphorus nutrition of Nothofagus dombeyi under drought conditions by regulating assimilative enzyme activities.

    PubMed

    Alvarez, Maricel; Huygens, Dries; Olivares, Erick; Saavedra, Isabel; Alberdi, Miren; Valenzuela, Eduardo

    2009-08-01

    Drought stress conditions (DC) reduce plant growth and nutrition, restraining the sustainable reestablishment of Nothofagus dombeyi in temperate south Chilean forest ecosystems. Ectomycorrhizal symbioses have been documented to enhance plant nitrogen (N) and phosphorus (P) uptake under drought, but the regulation of involved assimilative enzymes remains unclear. We studied 1-year-old N. dombeyi (Mirb.) Oerst. plants in association with the ectomycorrhizal fungi Pisolithus tinctorius (Pers.) Coker & Couch. and Descolea antartica Sing. In greenhouse experiments, shoot and root dry weights, mycorrhizal colonization, foliar N and P concentrations, and root enzyme activities [glutamate synthase (glutamine oxoglutarate aminotransferase (GOGAT), EC 1.4.1.13-14), glutamine synthetase (GS, EC 6.3.1.2), glutamate dehydrogenase (GDH, EC 1.4.1.2-4), nitrate reductase (NR, EC 1.6.6.1), and acid phosphomonoesterase (PME, EC 3.1.3.1-2)] were determined as a function of soil-water content. Inoculation of N. dombeyi with P. tinctorius and D. antartica significantly stimulated plant growth and increased plant foliar N and P concentrations, especially under DC. Ectomycorrhizal inoculation increased the activity of all studied enzymes relative to non-mycorrhizal plants under drought. We speculate that GDH is a key enzyme involved in the enhancement of ectomycorrhizal carbon (C) availability by fuelling the tricarboxylic acid (TCA) cycle under conditions of drought-induced carbon deficit. All studied assimilative enzymes of the ectomycorrhizal associations, involved in C, N, and P transfers, are closely interlinked and interdependent. The up-regulation of assimilative enzyme activities by ectomycorrhizal fungal root colonizers acts as a functional mechanism to increase seedling endurance to drought. We insist upon incorporating ectomycorrhizal inoculation in existing Chilean afforestation programs.

  17. Genetic differentiation in spite of high gene flow in the dominant rainforest tree of southeastern Australia, Nothofagus cunninghamii

    PubMed Central

    Duncan, C J; Worth, J R P; Jordan, G J; Jones, R C; Vaillancourt, R E

    2016-01-01

    Nothofagus cunninghamii is a long-lived, wind-pollinated tree species that dominates the cool temperate rainforests of southeastern Australia. The species' distribution is more or less continuous in western Tasmania but is fragmented elsewhere. However, it is unknown whether this fragmentation has affected the species' genetic architecture. Thus, we examined N. cunninghamii using 12 nuclear microsatellites and 633 individuals from 18 populations spanning the species' natural range. Typical of wind-pollinated trees, there was low range-wide genetic structure (FST=0.04) consistent with significant gene flow across most of the species' range. However, gene flow was not high enough to overcome the effects of drift across some disjunctions. Victorian populations (separated from Tasmania by the 240 km wide Bass Strait) formed a genetic group distinct from Tasmanian populations, had lower diversity (mean allelic richness (Ar)=5.4 in Victoria versus 6.9 in Tasmania) and were significantly more differentiated from one another than those in Tasmania (FST=0.045 in Victoria versus 0.012 in Tasmania). Evidence for bottlenecking was found in small populations that were at least 20 km from other populations. Interestingly, we found little divergence in microsatellite markers between the extremes of genetically based morphological and physiological altitudinal clines suggesting adaptive differentiation is strongly driven by selection because it is likely to be occurring in the presence of gene flow. Even though the cool temperate rainforests of Australia are highly relictual, the species is relatively robust to population fragmentation due to high levels of genetic diversity and gene flow, especially in Tasmania. PMID:26350630

  18. Using Genome-Wide SNP Discovery and Genotyping to Reveal the Main Source of Population Differentiation in Nothofagus dombeyi (Mirb.) Oerst. in Chile

    PubMed Central

    González, Jorge; Fuentes, Glenda; Alarcón, Diego; Ruiz, Eduardo

    2016-01-01

    Within a woody plant species, environmental heterogeneity has the potential to influence the distribution of genetic variation among populations through several evolutionary processes. In some species, a relationship between environmental characteristics and the distribution of genotypes can be detected, showing the importance of natural selection as the main source of differentiation. Nothofagus dombeyi (Mirb.) Oerst. (Nothofagaceae) is an endemic tree species occurring both in Chile and in Argentina temperate forests. Postglacial history has been studied with chloroplast DNA and evolutionary forces shaping genetic variation patterns have been analysed with isozymes but fine-scale genetic diversity studies are needed. The study of demographic and selection histories in Nothofagus dombeyi requires more informative markers such as single nucleotide polymorphisms (SNP). Genotyping-by-Sequencing tools now allow studying thousands of SNP markers at reasonable prices in nonmodel species. We investigated more than 10 K SNP loci for signatures of local adaptation and showed that interrogation of genomic resources can identify shifts in genetic diversity and putative adaptive signals in this nonmodel woody species. PMID:27446942

  19. Tree-Ring Stable Isotopes Reveal Twentieth-Century Increases in Water-Use Efficiency of Fagus sylvatica and Nothofagus spp. in Italian and Chilean Mountains

    PubMed Central

    Tognetti, Roberto; Lombardi, Fabio; Lasserre, Bruno; Cherubini, Paolo; Marchetti, Marco

    2014-01-01

    Changes in intrinsic water use efficiency (iWUE) were investigated in Fagus sylvatica and Nothofagus spp. over the last century. We combined dendrochronological methods with dual-isotope analysis to investigate whether atmospheric changes enhanced iWUE of Fagus and Nothofagus and tree growth (basal area increment, BAI) along latitudinal gradients in Italy and Chile. Post-maturation phases of the trees presented different patterns in δ13C, Δ13C, δ18O, Ci (internal CO2 concentration), iWUE, and BAI. A continuous enhancement in isotope-derived iWUE was observed throughout the twentieth century, which was common to all sites and related to changes in Ca (ambient CO2 concentration) and secondarily to increases in temperature. In contrast to other studies, we observed a general increasing trend of BAI, with the exception of F. sylvatica in Aspromonte. Both iWUE and BAI were uncoupled with the estimated drought index, which is in agreement with the absence of enduring decline in tree growth. In general, δ13C and δ18O showed a weak relationship, suggesting the major influence of photosynthetic rate on Ci and δ13C, and the minor contribution of the regulation of stomatal conductance to iWUE. The substantial warming observed during the twentieth century did not result in a clear pattern of increased drought stress along these latitudinal transects, because of the variability in temporal trends of precipitation and in specific responses of populations. PMID:25398040

  20. The CCR4 deadenylase acts with Nanos and Pumilio in the fine-tuning of Mei-P26 expression to promote germline stem cell self-renewal.

    PubMed

    Joly, Willy; Chartier, Aymeric; Rojas-Rios, Patricia; Busseau, Isabelle; Simonelig, Martine

    2013-01-01

    Translational regulation plays an essential role in Drosophila ovarian germline stem cell (GSC) biology. GSC self-renewal requires two translational repressors, Nanos (Nos) and Pumilio (Pum), which repress the expression of differentiation factors in the stem cells. The molecular mechanisms underlying this translational repression remain unknown. Here, we show that the CCR4 deadenylase is required for GSC self-renewal and that Nos and Pum act through its recruitment onto specific mRNAs. We identify mei-P26 mRNA as a direct and major target of Nos/Pum/CCR4 translational repression in the GSCs. mei-P26 encodes a protein of the Trim-NHL tumor suppressor family that has conserved functions in stem cell lineages. We show that fine-tuning Mei-P26 expression by CCR4 plays a key role in GSC self-renewal. These results identify the molecular mechanism of Nos/Pum function in GSC self-renewal and reveal the role of CCR4-NOT-mediated deadenylation in regulating the balance between GSC self-renewal and differentiation.

  1. Depletion of the Trypanosome Pumilio Domain Protein PUF2 or of Some Other Essential Proteins Causes Transcriptome Changes Related to Coding Region Length

    PubMed Central

    Jha, Bhaskar Anand; Fadda, Abeer; Merce, Clementine; Mugo, Elisha; Droll, Dorothea

    2014-01-01

    Pumilio domain RNA-binding proteins are known mainly as posttranscriptional repressors of gene expression that reduce mRNA translation and stability. Trypanosoma brucei has 11 PUF proteins. We show here that PUF2 is in the cytosol, with roughly the same number of molecules per cell as there are mRNAs. Although PUF2 exhibits a low level of in vivo RNA binding, it is not associated with polysomes. PUF2 also decreased reporter mRNA levels in a tethering assay, consistent with a repressive role. Depletion of PUF2 inhibited growth of bloodstream-form trypanosomes, causing selective loss of mRNAs with long open reading frames and increases in mRNAs with shorter open reading frames. Reexamination of published RNASeq data revealed the same trend in cells depleted of some other proteins. We speculate that these length effects could be caused by inhibition of the elongation phase of transcription or by an influence of translation status or polysomal conformation on mRNA decay. PMID:24681684

  2. Drosophila Nanos acts as a molecular clamp that modulates the RNA-binding and repression activities of Pumilio

    SciTech Connect

    Weidmann, Chase A.; Qiu, Chen; Arvola, René M.; Lou, Tzu-Fang; Killingsworth, Jordan; Campbell, Zachary T.; Tanaka Hall, Traci M.; Goldstrohm, Aaron C.

    2016-08-02

    Collaboration among the multitude of RNA-binding proteins (RBPs) is ubiquitous, yet our understanding of these key regulatory complexes has been limited to single RBPs. We investigated combinatorial translational regulation byDrosophilaPumilio (Pum) and Nanos (Nos), which control development, fertility, and neuronal functions. Our results show how the specificity of one RBP (Pum) is modulated by cooperative RNA recognition with a second RBP (Nos) to synergistically repress mRNAs. Crystal structures of Nos-Pum-RNA complexes reveal that Nos embraces Pum and RNA, contributes sequence-specific contacts, and increases Pum RNA-binding affinity. Nos shifts the recognition sequence and promotes repression complex formation on mRNAs that are not stably bound by Pum alone, explaining the preponderance of sub-optimal Pum sites regulatedin vivo. Our results illuminate the molecular mechanism of a regulatory switch controlling crucial gene expression programs, and provide a framework for understanding how the partnering of RBPs evokes changes in binding specificity that underlie regulatory network dynamics.

  3. Spatial and temporal patterns of alkaloid variation in the poison frog Oophaga pumilio in Costa Rica and Panama over 30 years.

    PubMed

    Saporito, Ralph A; Donnelly, Maureen A; Jain, Poonam; Martin Garraffo, H; Spande, Thomas F; Daly, John W

    2007-11-01

    A total of 232 alkaloids, representing 21 structural classes were detected in skin extracts from the dendrobatid poison frog Oophaga pumilio, collected from 53 different populations from over 30 years of research. The highly toxic pumiliotoxins and allopumiliotoxins, along with 5,8-disubstitiuted and 5,6,8-trisubstituted indolizidines, all of which are proposed to be of dietary mite origin, were common constituents in most extracts. One decahydroquinoline (DHQ), previously shown be of ant origin, occurred in many extracts often as a major alkaloid, while other DHQs occurred rather infrequently. Histrionicotoxins, thought to be of ant origin, did not appear to possess a specific pattern of occurrence among the populations, but when present, were usually found as major components. Certain 3,5-disubstituted pyrrolizidines and indolizidines, known to be of ant origin, did occur in extracts, but infrequently. Alkaloid composition differed with regard to geographic location of frog populations, and for populations that were sampled two or more times during the 30-year period significant changes in alkaloid profiles sometimes occurred. The results of this study indicate that chemical defense in a dendrobatid poison frog is dependent on geographic location and habitat type, which presumably controls the abundance and nature of alkaloid-containing arthropods.

  4. Establishment of ectomycorrhizal fungal community on isolated Nothofagus cunninghamii seedlings regenerating on dead wood in Australian wet temperate forests: does fruit-body type matter?

    PubMed

    Tedersoo, Leho; Gates, Genevieve; Dunk, Chris W; Lebel, Teresa; May, Tom W; Kõljalg, Urmas; Jairus, Teele

    2009-08-01

    Decaying wood provides an important habitat for animals and forms a seed bed for many shade-intolerant, small-seeded plants, particularly Nothofagus. Using morphotyping and rDNA sequence analysis, we compared the ectomycorrhizal fungal community of isolated N. cunninghamii seedlings regenerating in decayed wood against that of mature tree roots in the forest floor soil. The /cortinarius, /russula-lactarius, and /laccaria were the most species-rich and abundant lineages in forest floor soil in Australian sites at Yarra, Victoria and Warra, Tasmania. On root tips of seedlings in dead wood, a subset of the forest floor taxa were prevalent among them species of /laccaria, /tomentella-thelephora, and /descolea, but other forest floor dominants were rare. Statistical analyses suggested that the fungal community differs between forest floor soil and dead wood at the level of both species and phylogenetic lineage. The fungal species colonizing isolated seedlings on decayed wood in austral forests were taxonomically dissimilar to the species dominating in similar habitats in Europe. We conclude that formation of a resupinate fruit body type on the underside of decayed wood is not necessarily related to preferential root colonization in decayed wood. Rather, biogeographic factors as well as differential dispersal and competitive abilities of fungal taxa are likely to play a key role in structuring the ectomycorrhizal fungal community on isolated seedlings in decaying wood.

  5. Reduced densities of the invasive wasp, Vespula vulgaris (Hymenoptera: Vespidae), did not alter the invertebrate community composition of Nothofagus forests in New Zealand.

    PubMed

    Duthie, Catherine; Lester, Philip J

    2013-04-01

    Invasive common wasps (Vespula vulgaris L.) are predators of invertebrates in Nothofagus forests of New Zealand. We reduced wasp densities by poisoning in three sites over three y. We predicted an increase in the number of invertebrates and a change in the community composition in sites where wasps were poisoned (wasps removed) relative to nearby sites where wasps were not poisoned (wasps maintained). Wasp densities were significantly reduced by an average of 58.9% by poisoning. Despite this reduction in wasp densities, native bush ants (Prolasius advenus Forel) were the only taxa that was significantly influenced by wasp removal. However, contrary to our predictions there were more ants caught in pitfall traps where wasps were maintained. We believe that the higher abundance of these ants is probably because of the scarcity of honeydew in wasp-maintained sites and compensatory foraging by ants in these areas. Otherwise, our results indicated no significant effects of reduced wasp densities on the total number of invertebrates, or the number of invertebrate families, observed in pitfall or Malaise traps. An analysis of community composition (permutational multivariate analysis of variance) also indicated no significant difference between wasp-removed or wasp-maintained communities. The most parsimonious explanation for our results is that although we significantly reduced wasp numbers, we may not have reduced numbers sufficiently or for a sufficiently long period, to see a change or recovery in the community.

  6. Experimental increase of testosterone levels in free-ranging juvenile male African striped mice (Rhabdomys pumilio) induces physiological, morphological, and behavioral changes.

    PubMed

    Raynaud, Julien; Müller, Karin; Schradin, Carsten

    2012-08-01

    Testosterone influences sexual differentiation in early development, and activates sexual maturation and sex-related behavior in males during puberty. Testosterone can also influence the expression of male alternative reproductive tactics, by either organizational effects (fixed tactics) or by activational effects (plastic tactics). However, the roles of testosterone in sexual maturation and at the same time the expression of alternative reproductive tactics have been little investigated experimentally, and studies of free-ranging mammals are lacking. We conducted a field experiment in free-ranging juvenile African striped mice (Rhabdomys pumilio), a species with alternative reproductive tactics. Juvenile male striped mice reaching puberty can remain in their family as philopatric group-living males with low testosterone levels, or they can disperse and become solitary living roamers with much higher testosterone levels. We tested whether experimentally increased testosterone levels in non-scrotal juvenile males induces puberty and leads to the expression of the roaming tactic. Testosterone-treated males received the hormone for 15days by silastic implants which were empty in control-treated males. When compared to control-treated males, testosterone-treated males had higher testosterone levels, lower corticosterone levels, and became scrotal with descended testes. Testosterone-treated males also had larger testes, larger epididymides, and showed indication of spermatogenesis. Testosterone-treated males did not become solitary-living roamers, but had larger home ranges than control males. We conclude that testosterone can induce sexual maturation and causes juvenile males to increase their home ranges, maybe to search for dispersal opportunities.

  7. Population genetic structure, genetic diversity, and natural history of the South American species of Nothofagus subgenus Lophozonia (Nothofagaceae) inferred from nuclear microsatellite data.

    PubMed

    Vergara, Rodrigo; Gitzendanner, Matthew A; Soltis, Douglas E; Soltis, Pamela S

    2014-06-01

    The effect of glaciation on the levels and patterns of genetic variation has been well studied in the Northern Hemisphere. However, although glaciation has undoubtedly shaped the genetic structure of plants in the Southern Hemisphere, fewer studies have characterized the effect, and almost none of them using microsatellites. Particularly, complex patterns of genetic structure might be expected in areas such as the Andes, where both latitudinal and altitudinal glacial advance and retreat have molded modern plant communities. We therefore studied the population genetics of three closely related, hybridizing species of Nothofagus (N. obliqua, N. alpina, and N. glauca, all of subgenus Lophozonia; Nothofagaceae) from Chile. To estimate population genetic parameters and infer the influence of the last ice age on the spatial and genetic distribution of these species, we examined and analyzed genetic variability at seven polymorphic microsatellite DNA loci in 640 individuals from 40 populations covering most of the ranges of these species in Chile. Populations showed no significant inbreeding and exhibited relatively high levels of genetic diversity (H E = 0.502-0.662) and slight, but significant, genetic structure (R ST = 8.7-16.0%). However, in N. obliqua, the small amount of genetic structure was spatially organized into three well-defined latitudinal groups. Our data may also suggest some introgression of N. alpina genes into N. obliqua in the northern populations. These results allowed us to reconstruct the influence of the last ice age on the genetic structure of these species, suggesting several centers of genetic diversity for N. obliqua and N. alpina, in agreement with the multiple refugia hypothesis.

  8. Population genetic structure, genetic diversity, and natural history of the South American species of Nothofagus subgenus Lophozonia (Nothofagaceae) inferred from nuclear microsatellite data

    PubMed Central

    Vergara, Rodrigo; Gitzendanner, Matthew A; Soltis, Douglas E; Soltis, Pamela S

    2014-01-01

    The effect of glaciation on the levels and patterns of genetic variation has been well studied in the Northern Hemisphere. However, although glaciation has undoubtedly shaped the genetic structure of plants in the Southern Hemisphere, fewer studies have characterized the effect, and almost none of them using microsatellites. Particularly, complex patterns of genetic structure might be expected in areas such as the Andes, where both latitudinal and altitudinal glacial advance and retreat have molded modern plant communities. We therefore studied the population genetics of three closely related, hybridizing species of Nothofagus (N. obliqua, N. alpina, and N. glauca, all of subgenus Lophozonia; Nothofagaceae) from Chile. To estimate population genetic parameters and infer the influence of the last ice age on the spatial and genetic distribution of these species, we examined and analyzed genetic variability at seven polymorphic microsatellite DNA loci in 640 individuals from 40 populations covering most of the ranges of these species in Chile. Populations showed no significant inbreeding and exhibited relatively high levels of genetic diversity (HE = 0.502–0.662) and slight, but significant, genetic structure (RST = 8.7–16.0%). However, in N. obliqua, the small amount of genetic structure was spatially organized into three well-defined latitudinal groups. Our data may also suggest some introgression of N. alpina genes into N. obliqua in the northern populations. These results allowed us to reconstruct the influence of the last ice age on the genetic structure of these species, suggesting several centers of genetic diversity for N. obliqua and N. alpina, in agreement with the multiple refugia hypothesis. PMID:25360279

  9. Tree size and light availability increase photochemical instead of non-photochemical capacities of Nothofagus nitida trees growing in an evergreen temperate rain forest.

    PubMed

    Coopman, Rafael E; Briceño, Verónica F; Corcuera, Luis J; Reyes-Díaz, Marjorie; Alvarez, Daniela; Sáez, Katherine; García-Plazaola, José I; Alberdi, Miren; Bravo, León A

    2011-10-01

    Nothofagus nitida (Phil.) Krasser (Nothofagaceae) regenerates under the canopy in microsites protected from high light. Nonetheless, it is common to find older saplings in clear areas and adults as emergent trees of the Chilean evergreen forest. We hypothesized that this shade to sun transition in N. nitida is supported by an increase in photochemical and non-photochemical energy dissipation capacities of both photosystems in parallel with the increase in plant size and light availability. To dissect the relative contribution of light environment and plant developmental stage to these physiological responses, the photosynthetic performance of both photosystems was studied from the morpho-anatomical to the biochemical level in current-year leaves of N. nitida plants of different heights (ranging from 0.1 to 7 m) growing under contrasting light environments (integrated quantum flux (IQF) 5-40 mol m(-2). Tree height (TH) and light environment (IQF) independently increased the saturated electron transport rates of both photosystems, as well as leaf and palisade thickness, but non-photochemical energy flux, photoinhibition susceptibility, state transition capacity, and the contents of D1 and PsbS proteins were not affected by IQF and TH. Spongy mesophyll thickness and palisade cell diameter decreased with IQF and TH. A(max), light compensation and saturation points, Rubisco and nitrogen content (area basis) only increased with light environment (IQF), whereas dark respiration (R(d)) decreased slightly and relative chlorophyll content was higher in taller trees. Overall, the independent effects of more illuminated environment and tree height mainly increased the photochemical instead of the non-photochemical energy flux. Regardless of the photochemical increase with TH, carbon assimilation only significantly improved with higher IQF. Therefore it seems that mainly acclimation to the light environment supports the phenotypic transition of N. nitida from shade to

  10. Intraspecific Relationships among Wood Density, Leaf Structural Traits and Environment in Four Co-Occurring Species of Nothofagus in New Zealand

    PubMed Central

    Richardson, Sarah J.; Allen, Robert B.; Buxton, Rowan P.; Easdale, Tomás A.; Hurst, Jennifer M.; Morse, Christopher W.; Smissen, Rob D.; Peltzer, Duane A.

    2013-01-01

    Plant functional traits capture important variation in plant strategy and function. Recent literature has revealed that within-species variation in traits is greater than previously supposed. However, we still have a poor understanding of how intraspecific variation is coordinated among different traits, and how it is driven by environment. We quantified intraspecific variation in wood density and five leaf traits underpinning the leaf economics spectrum (leaf dry matter content, leaf mass per unit area, size, thickness and density) within and among four widespread Nothofagus tree species in southern New Zealand. We tested whether intraspecific relationships between wood density and leaf traits followed widely reported interspecific relationships, and whether variation in these traits was coordinated through shared responses to environmental factors. Sample sites varied widely in environmental variables, including soil fertility (25–900 mg kg–1 total P), precipitation (668–4875 mm yr–1), temperature (5.2–12.4 °C mean annual temperature) and latitude (41–46 °S). Leaf traits were strongly correlated with one another within species, but not with wood density. There was some evidence for a positive relationship between wood density and leaf tissue density and dry matter content, but no evidence that leaf mass or leaf size were correlated with wood density; this highlights that leaf mass per unit area cannot be used as a surrogate for component leaf traits such as tissue density. Trait variation was predicted by environmental factors, but not consistently among different traits; e.g., only leaf thickness and leaf density responded to the same environmental cues as wood density. We conclude that although intraspecific variation in wood density and leaf traits is strongly driven by environmental factors, these responses are not strongly coordinated among functional traits even across co-occurring, closely-related plant species. PMID:23527041

  11. [Epiphytic algae from Bajo Pepito, Isla Mujeres, Quintana Roo, Mexico].

    PubMed

    Quan-Young, L I; Díaz-Martín, M A; Espinoza-Avalos, J

    2006-06-01

    A total of 96 epiphytic algae species were identified from Bajo Pepito, Quintana Roo, México. 60.4% (58) belonged to the Rhodophyta, 19.79% (19) to the Phaeophyta, 16.6% (16) to the Chlorophyta and 3.1% (3) to the Cyanophyta; 49 species (50.5%) were found only in one month, while Heterosiphonia crispella was found in all of the sampled months. That species provided the largest contribution to the biomass of epiphytes. During January we registered the greater biommass and richness of epiphytes species, coincidently with high values of host species cover and rainfall.

  12. Effects of leaf age and tree size on stomatal and mesophyll limitations to photosynthesis in mountain beech (Nothofagus solandrii var. cliffortiodes).

    PubMed

    Whitehead, David; Barbour, Margaret M; Griffin, Kevin L; Turnbull, Matthew H; Tissue, David T

    2011-09-01

    Mesophyll conductance, g(m), was estimated from measurements of stomatal conductance to carbon dioxide transfer, g(s), photosynthesis, A, and chlorophyll fluorescence for Year 0 (current-year) and Year 1 (1-year-old) fully sunlit leaves from short (2 m tall, 10-year-old) and tall (15 m tall, 120-year-old) Nothofagus solandrii var. cliffortiodes trees growing in adjacent stands. Rates of photosynthesis at saturating irradiance and ambient CO(2) partial pressure, A(satQ), were 25% lower and maximum rates of carboxylation, V(cmax), were 44% lower in Year 1 leaves compared with Year 0 leaves across both tree sizes. Although g(s) and g(m) were not significantly different between Year 0 and Year 1 leaves and g(s) was not significantly different between tree heights, g(m) was significantly (19%) lower for leaves on tall trees compared with leaves on short trees. Overall, V(cmax) was 60% higher when expressed on the basis of CO(2) partial pressure at the chloroplasts, C(c), compared with V(cmax) on the basis of intercellular CO(2) partial pressure, C(i), but this varied with leaf age and tree size. To interpret the relative stomatal and mesophyll limitations to photosynthesis, we used a model of carbon isotopic composition for whole leaves incorporating g(m) effects to generate a surface of 'operating values' of A over the growing season for all leaf classes. Our analysis showed that A was slightly higher for leaves on short compared with tall trees, but lower g(m) apparently reduced actual A substantially compared with A(satQ). Our findings showed that lower rates of photosynthesis in Year 1 leaves compared with Year 0 leaves were attributable more to increased biochemical limitation to photosynthesis in Year 1 leaves than differences in g(m). However, lower A in leaves on tall trees compared with those on short trees could be attributed in part to lower g(m) and higher stomatal, L(s), and mesophyll, L(m), limitations to photosynthesis, consistent with steeper hydraulic

  13. Morphology, geology and geochemistry of the "Salar del Gran Bajo del Gualicho" (Rio Negro, Argentina)

    USGS Publications Warehouse

    Angelucci, A.; Barbieri, M.; Brodtkorb, A.; Ciccacci, S.; Civitelli, G.; De Barrio, R.; Di, Filippo M.; Fredi, P.; Friedman, I.; Lombardi, S.; Schalamuk, A.I.; Toro, B.

    1996-01-01

    A multidisciplinary study of the Gran Bajo del Gualicho area (Rio Negro - Argentina) was carried out; the aim was to delineate its geological and geomorphological evolution and to estabilish the genesis of salts filling the depression. Climatic conditions were analized first to individuate their role in the present morphogenetic processes; moreover the main morphological features of present landscape were examined as well as the stratigraphy of the outcropping formations, and of the Gran Bajo del Gualicho Formation in particular. Finally, a possible geomorphological evolution of the studied area was traced. Geophysical analyses allowed to estabilish that the paleosurface shaped on the crystalline basement is strongly uneven and shows evidence of the strong tectonic phases it underwent. The result of isotope analyses confirmed that the salt deposits on the Gran Bajo del Gualicho bottom were produced by fresh water evaporation, while strontium isotope ratio suggested that such waters were responsible for solubilization of more ancient evaporitic deposits.

  14. Quaternary active tectonic structures in the offshore Bajo Segura basin (SE Iberian Peninsula - Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Perea, H.; Gràcia, E.; Alfaro, P.; Bartolomé, R.; Lo Iacono, C.; Moreno, X.; Masana, E.; Event-Shelf Team

    2012-10-01

    The Bajo Segura fault zone (BSFZ) is the northern terminal splay of the Eastern Betic shear zone (EBSZ), a large left-lateral strike-slip fault system of sigmoid geometry stretching more than 450 km from Alicante to Almería. The BSFZ extends from the onshore Bajo Segura basin further into the Mediterranean Sea and shows a moderate instrumental seismic activity characterized by small earthquakes. Nevertheless, the zone was affected by large historical earthquakes of which the largest was the 1829 Torrevieja earthquake (IEMS98 X). The onshore area of the BSFZ is marked by active transpressive structures (faults and folds), whereas the offshore area has been scarcely explored from the tectonic point of view. During the EVENT-SHELF cruise, a total of 10 high-resolution single-channel seismic sparker profiles were obtained along and across the offshore Bajo Segura basin. Analysis of these profiles resulted in (a) the identification of 6 Quaternary seismo-stratigraphic units bounded by five horizons corresponding to regional erosional surfaces related to global sea level lowstands; and (b) the mapping of the active sub-seafloor structures and their correlation with those described onshore. Moreover, the results suggest that the Bajo Segura blind thrust fault or the Torrevieja left-lateral strike-slip fault, with prolongation offshore, could be considered as the source of the 1829 Torrevieja earthquake. These data improve our understanding of present deformation along the BSFZ and provide new insights into the seismic hazard in the area.

  15. [Crustaceans associated to macroalgae in Bajo Pepito, Isla Mujeres, Mexican Caribbean].

    PubMed

    Campos Vázquez, C

    2000-01-01

    Crustaceans associated with macroalgae were collected for one year by scuba diving in Bajo Pepito, Isla Mujeres, mexican Caribbean. A total of 148 organisms were found: three orders, 11 families, 18 genera and 19 species in nine types of associations. The order with highest abundance was Isopoda (112), followed by Amphipoda (20) and Decapoda (16).

  16. An experimental approach to explain the southern Andes elevational treeline.

    PubMed

    Fajardo, Alex; Piper, Frida I

    2014-05-01

    • The growth limitation hypothesis (GLH) is the most accepted mechanistic explanation for treeline formation, although it is still uncertain whether it applies across taxa. The successful establishment of Pinus contorta--an exotic conifer species in the southern hemisphere--above the Nothofagus treeline in New Zealand may suggest a different mechanism. We tested the GLH in Nothofagus pumilio and Pinus contorta by comparing seedling performance and carbon (C) balance in response to low temperatures.• At a southern Chilean treeline, we grew seedlings of both species 2 m above ground level, to simulate coupling between temperatures at the meristem and in the air (colder), and at ground level, i.e., decoupling air temperature (relatively milder). We recorded soil and air temperatures as well. After 3 yr, we measured seedling survival and biomass (as a surrogate of growth) and determined nonstructural carbohydrates (NSC).• Nothofagus and Pinus did not differ in survival, which, as a whole, was higher at ground level than at the 2-m height. The root-zone temperature for the growing season was 6.6°C. While biomass and NSC decreased significantly for Nothofagus at the 2-m height compared with ground level (C limitation), these trends were not significant for Pinus• The treeline for Nothofagus pumilio is located at an isotherm that fully matches global patterns; however, its physiological responses to low temperatures differed from those of other treeline species. Support for C limitation in N. pumilio but not in P. contorta indicates that the physiological mechanism explaining their survival and growth at treeline may be taxon-dependent. © 2014 Botanical Society of America, Inc.

  17. Evaluation of Bajo Blanco Sandbar as a Potential Beach Nourishment Borrow Site for Eroding Beaches in Rincon, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Rojas, C. A.; Canals, M.

    2016-02-01

    The municipality of Rincón, Puerto Rico is recognized for its world-class surfing beaches. Unfortunately, the coast from Punta Higüero to Punta Cadena in Rincón is experiencing long-term erosion (Thieler 2007), which has caused the destruction of many beachfront homes and hotels and had negative impacts on the local tourism-driven economy. The purpose of this project is to evaluate whether the nearby Bajo Blanco sandbar, located just offshore of these eroded beaches, could be used as a possible beach nourishment borrow site. A high-resolution bathymetric survey of Bajo Blanco sandbar was conducted along with a grain size analysis to compare the grain size distribution of the Bajo Blanco sandbar with the sediment properties of the eroded beaches. It was found that the sediment from Bajo Blanco is finer yet may be suitable as beach fill material for these beaches according to Dean's overfill ratio. Compatibility analysis suggests a total volume of sandbar sediment of approximately 685,555 cubic meters to allow successful beach equilibrium. To evaluate the potential effects of the sand extraction on the nearshore wave climate, numerical simulations were performed using the spectral wave model of the USACE Coastal Modeling System (CMS-Wave). Wave model results for several dredging scenarios suggest that wave energy flux concentrates around the shoal causing an increase in wave height at the northern and southern edges of the shoal. Therefore, conservation of energy leads to a reduction of wave energy flux shoreward of the shoal, causing a shadow of reduced wave height. In addition, the Tres Palmas Marine reserve is located just north of Bajo Blanco sandbar and features some of the healthiest Elkorn Corals in the Caribbean. To avoid excessive sedimentation of these reefs during dredging activities, the Particle Tracking Module (PTM), integrated in the Surface-water Modeling System (SMS), was used to evaluate the Lagrangian particle transport processes along Bajo

  18. Preliminary data on growth and enzymatic abilities of soil fungus Humicolopsis cephalosporioides at different incubation temperatures.

    PubMed

    Elíades, Lorena Alejandra; Cabello, Marta N; Pancotto, Verónica; Moretto, Alicia; Rago, María Melisa; Saparrat, Mario C N

    2015-01-01

    Nothofagus pumilio (Poepp & Endl.) Krasser, known as "lenga" is the most important timber wood species in southernmost Patagonia (Argentina). Humicolopsis cephalosporioides Cabral & Marchand is a soil fungus associated with Nothofagus pumilio forests, which has outstanding cellulolytic activity. However, there is no information about the ability of this fungus to use organic substrates other than cellulose, and its ability to produce different enzyme systems, as well as its response to temperature. The aim of this study was to examine the role of H. cephalosporioides in degradation processes in N. pumilio forests in detail by evaluating the in vitro ability of four isolates of this fungus to grow and produce different lytic enzyme systems, and their response to incubation temperature. The ability of the fungi to grow and produce enzyme systems was estimated by inoculating them on agar media with specific substrates, and the cultures were incubated at three temperatures. A differential behavior of each strain in levels of growth and enzyme activity was found according to the medium type and/or incubation temperature. A intra-specific variability was found in H. cephalosporioides. Likewise a possible link between the saprotrophic role of this fungus in N. pumilio forests and the degradation of organic matter under stress conditions, such as those from frosty environments, was also discussed. Copyright © 2013 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

  19. GPS deformation rates in the Bajo Segura Basin (NE of the Eastern Betic Shear Zone, SE Spain)

    NASA Astrophysics Data System (ADS)

    Jesús Borque, María; Sánchez-Alzola, Alberto; Estévez, Antonio; García-Tortosa, Francisco J.; Martín-Rojas, Iván; Molina, Sergio; Alfaro, Pedro; Rodríguez-Caderot, Gracia; de Lacy, Clara; García-Armenteros, Juan Antonio; Avilés, Manuel; Herrera, Antonio; Rosa-Cintas, Sergio; Gil, Antonio J.

    2014-05-01

    The Bajo Segura Basin, located in the NE end of the Eastern Betic Shear Zone, is one of the areas with highest seismic activity of the Iberian Peninsula. It is bounded by the Crevillente Fault to the north and the Bajo Segura Fault to the south, and it is characterized by a Late Miocene to Quaternary folded cover. We estimate the present-day deformation of the study area from a GPS network with 11 sites. Observation campaigns were carried out four times (June 1999, September 2001, September 2002 and September 2013). We used the 6.2 version of GIPSY-OASIS software to process GPS data in Precise Point Positioning mode (PPP). In order to obtain the position time series in the whole period of these episodic campaigns, all the GPS observations from 1999 to 2013 campaigns were processed with an identical standard procedure. We compared our velocity field estimation with respect to GEODVEL tectonic model to obtain the residual velocity field of the Bajo Segura Basin. We estimated a ~N-S shortening with deformation rates varying between 0.2 and 0.6 mm/yr. These results are consistent with local geological deformation rates although slightly higher. They also fit well with regional geodetic data estimated for the Western Mediterranean.

  20. Trends in prevalence and incidence of multiple sclerosis in Bajo Aragón, Spain.

    PubMed

    Modrego, Pedro J; Pina, Miguel A

    2003-12-15

    Recent reports provide consistent evidence that Spain is an area of high risk for multiple sclerosis (MS) according to prevalence surveys. However, the studies of incidence are scarce. The objective of the current work is to analyse whether the increased prevalence of MS is accompanied by increasing incidence in the area of Bajo Aragón, northeastern Spain. The data of both prevalence and incidence were retrieved from a prospective register created in 1994 and which included patients with probable or definite MS. Crude and age-standardised rates were calculated from 1994 to 2002 and compared with those found retrospectively in the previous period of 1984-1993. In January 2003, we found a prevalence rate of 75/100,000 (95% CI: 52-97) whereas it was 35/100,000 (95% CI: 20-50) in 1994. In a period of 9 years, 25 new cases were diagnosed in the area with a mean annual incidence rate of 4.6/100,000 (95% CI: 2.8-6.5; range: 1.6-13.6) in comparison to 17 new cases from 1984 to 1993 with a mean incidence rate of 3/100,000 (95% CI: 1.6-4.5). The standardised ratio of incidences was 1.44 (95% CI: 0.95-2.17) and, therefore, the difference of rates was not significant. We conclude that the increase in prevalence of MS is more likely to be due to improvement on case ascertainment than to increasing incidence. Nonetheless, further prospective incidence studies in larger populations are warranted in Spain to elucidate whether the frequency of this disease is truly increasing.

  1. Timescales of Porphyry Cu Formation: Bajo de la Alumbrera, NW Argentina

    NASA Astrophysics Data System (ADS)

    Buret, Y.; Von Quadt, A.; Heinrich, C. A.; Peytcheva, I.

    2014-12-01

    Using high-precision U-Pb dating we are potentially able to determine timescales of porphyry emplacement and ore formation. Previous studies have suggested timescales of porphyry Cu formation ranging from <100 yr, based on modelling diffusive equilibrium between fluids and altered rocks [1], to as much as 1 Ma using U-Pb LA-ICP-MS and SHRIMP dating techniques on zircons [2], [3]. In contrast recent numerical simulations suggest Cu precipitation occurs in the range of 50-100 ka [4]. Therefore in order to better constrain timescales of porphyry Cu formation, we apply high precision U-Pb zircon geochronology, using the youngest zircon date to estimate the emplacement age of each porphyry [5].This study focuses on the ~7 Ma Bajo de la Alumbrera Cu-Au deposit, NW Argentina. The deposit consists of a composite stock of dacitic porphyries. The relative timing of each porphyry intrusion is established based on clear cross-cutting relationships between different porphyry intrusions, which include the pre-mineralisation P2 porphyry, pre-syn-minerlisation EP3 porphyry, and the post-mineralisation LP3 and P4 porphyries.Single zircon crystals from individual porphyry intrusions (P2, EP3, LP3, P4) in the Alumbrera deposit have been dated using CA-ID-TIMS, employing the ET2535 tracer solution for maximum precision and accuracy. All porphyries display protracted zircon crystal growth over 100-200 ka timescales. Using the youngest zircons from each of the porphyry intrusions, Cu mineralisation occurred on 10 ka timescales, similar to those proposed by recent numerical predictions [4]. Trace element and Hf isotopic analyses may reveal geochemical distinctions within the porphyry intrusions and record temporal changes in the magmatic evolution. References: [1] Cathles and Shannon (2007) EPSL 262:92-108; [2] Ballard et al. (2001) Geology 29:383-386; [3] Harris et al. (2008) Min Dep 43: 295-314; [4] Weis et al. (2012) Science 338: 1613-1616; [5] von Quadt et al. (2011) Geology 39: 731-734.

  2. The stratigraphic record of the Messinian salinity crisis in the northern margin of the Bajo Segura Basin (SE Spain)

    NASA Astrophysics Data System (ADS)

    Soria, J. M.; Caracuel, J. E.; Yébenes, A.; Fernández, J.; Viseras, C.

    2005-08-01

    The Bajo Segura Basin is a marginal basin of the Western Mediterranean located on the eastern end of the Betic Cordillera (southeastern Spain). Its Messinian and Pliocene stratigraphic record is divided into four allostratigraphic units, with bounding unconformities represented by erosional surfaces corresponding to palaeogeographic changes. The Messinian Unit I (MI) is composed of three depositional systems (fluvial, coastal lagoon, and shelf) which lateral facies changes, deposited in a context of sea level highstand. The upper boundary of the MI Unit corresponds to the intra-Messinian unconformity, a lowstand erosional surface with palaeovalleys of 30 m deep generated by a sea level fall. Messinian Unit II (MII) comprises five correlative depositional systems (from fluvial to coastal) deposited during a new sea level highstand after a reflooding that followed the preceding lowstand. The upper boundary of Unit MII corresponds to the end-Messinian unconformity, which is another lowstand erosional surface with similar palaeovalleys to those of the intra-Messinian unconformity. Messinian Unit MIII forms the fluvial fill of some small incised palaeovalleys, developed during the end-Messinian lowstand. Over the end-Messinian unconformity lies the Pliocene Unit (P), which consists of four depositional systems superimposed in continuity. The first two (littoral and open marine) form a transgressive assemblage that fill the palaeovalley carved over the end-Messinian unconformity. The latter two (shallow marine to coastal in the lower part, and fluvial in the upper part) form a regressive prograding assemblage deposited in a highstand context, when the sea level reached its height in the early Pliocene. In relation to the Messinian salinity crisis, we propose that Unit MII is correlative to the evaporites deposited in the centre of the Bajo Segura Basin (San Miguel Gypsum Formation), corresponding to the marginal evaporites of the Mediterranean. Evaporitic sedimentation

  3. A Long-Lived Porphyry Ore Deposit and Associated Upper Crustal Silicic Magma Body, Bajo de la Alumbrera, Argentina

    NASA Astrophysics Data System (ADS)

    Harris, A. C.; Allen, C. M.; Reiners, P. W.; Dunlap, W. J.; Cooke, D. R.; Campbell, I. H.; White, N. C.

    2004-05-01

    Porphyry Cu deposits form within and adjacent to small porphyritic intrusions that are apophyses to larger silicic magma bodies that reside in the upper parts of the Earth's crusts. Centred on these intrusions are hydrothermal systems of exsolved magmatic fluid with a carapace of convectively circulating meteoric water. We have applied several different dating techniques to assess the longevity of the magmatic-hydrothermal system and to define the cooling history of porphyry intrusions at the Bajo de la Alumbrera porphyry Cu-Au deposit, Argentina. The closure temperatures of these techniques range from 800oC (zircon U-Pb) to ~70oC (apatite (U-Th)/He; Fig. 1). The resulting cooling history indicates that the magmatic-hydrothermal system cooled to ca. 200oC by ~1.5 m.y. after the last porphyry intrusion (i.e., 6.96±0.09 Ma; U-Pb zircon age). Based on (U-Th)/He apatite data (closure temperature ~60-70oC), exposure and cessation of the system occurred before 4 Ma. The longevity of the magmatic-hydrothermal system indicated by these results is inconsistent with accepted mechanisms for porphyry Cu deposit formation. Depending on wallrock permeability, depth and cooling method, a 2 km wide by 3 km high intrusion has been predicted to cool between 0.01 to 0.1 m.y. (marked as the grey interval; Cathles et al., 1997 Economic Geology). We have obtained numerous age determinations younger than the U-Pb zircon age of the last known intrusion at Bajo de la Alumbrera. These imply that simple cooling of the small, mineralized porphyries did not happen. For the magmatic-hydrothermal system to have been sustained for longer than 0.1 m.y., either 1) younger small intrusions have been episodically emplaced below the youngest known intrusions, thus prolonging heat flow, or 2) fluids derived from a deeper and larger parental intrusion have been episodically discharged through the ore deposit long after the porphyry intrusion had lost its available heat. In either case, the longevity of

  4. The Upper Triassic alkaline magmatism of the western Neo-Tethys (Bajo Ebro, NE Spain): age and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Sanz, T.; Lago, M.; Gil, A.; Pocoví, A.; Galé, C.; Ubide, T.; Larrea, P.; Ramajo, J.; Tierz, P.

    2012-04-01

    A set of mafic rocks crop out in the north-western margin of the Neo-Tethys (eastern Spain and France). These rocks show three common features: 1) they were emplaced into Upper Triassic sediments (Keuper facies), 2) they are mainly basalts and dolerites and show an alkaline geochemical affinity and 3) these magmas rose to their emplacement level through deep fractures; some of the fractures were newly opened as a result of the Triassic extension (Triassic-Liassic rifting), whereas others had been generated during the Permian extension (Lower Permian rifting) and were reopened. Magmatic activity has also been recognized in these areas during the Jurassic, the Cretaceous and the Quaternary. The Bajo Ebro sector (NE Spain) comprises two types of Upper Triassic mafic rocks: 1) massive rocks emplaced as dikes, sills and basaltic lavas (10-12 meters in thickness and up to kilometric in extension) and 2) a wide range of pyroclasts (from ash grains to bombs) forming layers more than 100 meters thick, which are usually interbedded with argillites and carbonates. Protrusions of the sills into the overlying sediments, together with spilitization of the igneous rocks, suggest that the magmas emplaced into unconsolidated sediments. Furthermore, a level of epiclastic-basaltic breccias is recognized overlying the magmatic levels and below the dolostones of the Imón Formation (Rhaetian in age); these breccias are interpreted to represent an erosive episode which affected the magmatic rocks in emerged areas. According to these criteria, these rocks can be considered Upper Triassic (pre-Rhaetian) in age. The basaltic lavas show alkaline mineral assemblages composed of: olivine (Fo79-65), Ti-rich clinopyroxene (Fs3-15, En52-35, Wo50-42), plagioclase (An80-50), Ti-rich magnetite and apatite. Their major and trace element whole rock compositions show contents in SiO2 (41,3-49,3 w.%), Nb/Y (1,5-4,1), Zr/TiO2 (0,0057-0,013), V (157,8-292,1 ppm) and Ti/1000 (11,3-18,53) which indicate

  5. Cyclically-arranged, storm-controlled, prograding lithosomes in Messinian terrigenous shelves (Bajo Segura Basin, western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Soria, Jesús M.; Giannetti, Alice; Monaco, Paolo; Corbí, Hugo; García-Ramos, Diego; Viseras, César

    2014-08-01

    This work focuses on a Messinian shallow-marine terrigenous unit, termed the La Virgen Formation, which forms part of the sedimentary infill of the Bajo Segura Basin (Betic margin of the western Mediterranean). This formation was deposited during a high sea level phase prior to the onset of the Messinian Salinity Crisis. Stratigraphically, it comprises a prograding stack of sandstone lithosomes alternating with marly intervals (1st-order cyclicity). These lithosomes are characterized by a homoclinal geometry that tapers distally, and interfinger with pelagic sediments rich in planktonic and benthic microfauna (Torremendo Formation). An analysis of sedimentary facies of each lithosome reveals a repetitive succession of sandy storm beds (tempestites), which are separated by thin marly layers (2nd-order cyclicity). Each storm bed contains internal erosional surfaces (3rd-order cyclicity) that delimit sets of laminae. Two categories of storm beds have been differentiated. The first one includes layers formed below storm wave base (SWB), characterized by traction structures associated to unidirectional flows. The second category consists of layers deposited above the SWB, which display typical high regime oscillatory flow structures. The 1st-order cyclicity recorded in the La Virgen Formation corresponds to sapropel/homogeneous marl precessional cycles formed in a pelagic basin context (Torremendo Formation).

  6. Incidence, mortality, and prevalence of end-stage chronic renal disease in the Bajo Lempa region of El Salvador: A ten-year community registry.

    PubMed

    García-Trabanino, Ramón; Hernández, Carolina; Rosa, Adrián; Domínguez Alonso, Jesús

    The Bajo Lempa is an impoverished rural coastal region of El Salvador affected by the chronic kidney disease (CKD) epidemic known as Mesoamerican nephropathy. The local community organisation Fondo Social de Emergencia para la Salud (FSES) (Emergency social fund for health) is helping to fight the epidemic in 42 communities of the region (19,223 inhabitants; average age 26.7 years; 48.5% male; 40.2% <18 years).

  7. Relationship between Bajo Pobre and Chon Aike formations (Deseado Massif, Patagonia, Argentina):a melt inclusions study

    NASA Astrophysics Data System (ADS)

    Busà, T.; Bellieni, G.; Fernandez, R.; Hecheveste, H.; Piccirillo, E. M.

    2003-04-01

    The Deseado Massif covers the centre-east of the Santa Cruz Province, in the extra-Andean Patagonia. Although the Deseado Massif is mainly composed of silicic volcanic rocks (Chon Aike Formation, CA; 151.5 ±0.5 - 177.8 ±0.4 Ma), mafic and intermediate volcanites (Bajo Pobre Formation, BP; 152.7 ±0.5 and 164 ±0.3 Ma) outcrop largely in the central part of the Massif. In this paper quarz-trapped melt inclusions (rhyolitic in composition) from selected samples of the BP and the CA are analysed. On the basis of major elements content, for BP the sequence from andesite (BP whole rock) to ryholite (trapped as inclusions in quartz) can be modelled by simple fractional crystallisation of ortho- and clinopyroxene, plagioclase, quartz and apatite. As regards trace elements, a good calculated/measured ratio (around 1 ±0.2) is obtained assuming only a relatively high apatite fractionation. Since the apatite fractionation amount is not acceptable for major elements, the evolution of BP Formation cannot be modelled by a simple process of fractional crystallisation, and a contamination process probably occurred. The sequence from BP to CA cannot be modelled by fractional crystallisation. 30% batch melting of BP andesite (BP whole rock) produces a magma from which the CA ryholites (trapped as inclusions in quartz) can be obtained by Rayleigh fractional crystallisation of ortho- and clinopyroxene, plagioclase, magnetite, quartz, apatite and small amounts of zircon and minor allanite. Since the latter one was not observed in the analysed sample, a contamination process during magma evolution cannot be completely excluded. Finally, on the basis of the different trace elements concentration (Nb anomaly, different content in LILE, B/Be and B/Nb), it is possible to suppose that, at the time of the BP and CA emplacement, a changing in the tectonic setting, from subduction to a lithospheric extension, was active.

  8. Quantitative subsidence-uplift analysis of the Bajo Segura Basin (eastern Betic Cordillera, Spain): tectonic control on the stratigraphic architecture

    NASA Astrophysics Data System (ADS)

    Soria, J. M.; Alfaro, P.; Fernández, J.; Viseras, C.

    2001-04-01

    The Bajo Segura Basin is located in the eastern Betic Cordillera, at present connected with the Mediterranean Sea to the east. It has a complete stratigraphic record from the Tortonian to the Quaternary, which has been separated into six units bounded by unconformities. This paper is concerned with the northern edge of the basin, controlled by a major strike-slip fault (the Crevillente Fault Zone, CFZ), where the most complete stratigraphic successions are found. The results obtained (summarised below) are based on an integrated analysis of the sedimentary evolution and the subsidence-uplift movements. Unit I (Early Tortonian) is transgressive on the basin basement and is represented by ramp-type platform facies, organised in a shallowing-upward sequence related to tectonic uplift during the first stages of movement along the CFZ. Unit II (lower Late Tortonian) consists of shallow platform facies at bottom and pelagic basin facies at top, forming a deepening-upward sequence associated with tectonic subsidence due to sinistral motion along the CFZ. Unit III (middle Late Tortonian) is made up of exotic turbiditic facies related to a stage of uplift and erosion of the southern edge of the basin. Unit IV (upper Late Tortonian) consists of pelagic basin facies at bottom and shallow platform facies at top, defining a shallowing-upward sequence related to tectonic uplift during continued sinistral movement on the basin-bounding fault. Units V (latest Tortonian-Messinian) and VI (Pliocene-Pleistocene p.p.) consist of shallowing-upward sequences deposited during folding and uplift of the northern margin of the basin. No definitive evidence of any major eustatic sea-level fall, associated with the 'Messinian salinity crisis', has been recorded in the stratigraphic sections studied.

  9. Sequestrate fungi from Patagonian Nothofagus forests: Cystangium (Russulaceae, Basidiomycota).

    PubMed

    Trierveiler-Pereira, Larissa; Smith, Matthew E; Trappe, James M; Nouhra, Eduardo R

    2015-01-01

    Six species of Cystangium, a genus of sequestrate taxa related to Russula, were collected in Patagonia (Argentina and Chile) during autumn 2001. Two species, C. depauperatum Singer & A.H. Sm. and C. nothofagi (E. Horak) Trappe, Castellano & T. Lebel, were already known from this region, while four new species, C. domingueziae, C. gamundiae, C. grandihyphatum and C. longisterigmatum, are described, illustrated and a key to the species is provided. In addition, sequences of the ITS (rDNA) region were obtained to explore the phylogenetic relationships of our South American Cystangium species. © 2015 by The Mycological Society of America.

  10. Carbon reservoirs in temperate South American Nothofagus forests.

    PubMed

    Böswald, Klaus; Lencinas, José D; Loguercio, Gabriel

    2002-01-08

    Humans are influencing the global carbon (C) cycle due to the combustion of fossil fuels and due to changes in land use management. These activities are fostering the manmade greenhouse effect and thus global climate change. Negative effects for life on earth are accounted for. Among others the international climate debate focused attention on forests and forestry, knowing about their considerable influence on global climate change. Whilst the global C budget is described fairly well, there is a lack of regional data describing the C reservoirs and flows in detail. This has to be constituted especially for forests in developing countries. This paper presents an investigation at regional scale of the C reservoirs in a South American forest ecosystem. The investigation puts emphasis on the area and stand volume estimation and the development of expansion and reduction factors. Vegetation types are classified and stratified, determining the corresponding areas and estimating the stand volume. Converting factors are developed to calculate C in branches and roots as a percentage of standing wood measured by inventories.

  11. Chronic kidney disease and associated risk factors in the Bajo Lempa region of El Salvador: Nefrolempa study, 2009.

    PubMed

    Orantes, Carlos M; Herrera, Raúl; Almaguer, Miguel; Brizuela, Elsy G; Hernández, Carlos E; Bayarre, Héctor; Amaya, Juan C; Calero, Denis J; Orellana, Patricia; Colindres, Rosa M; Velázquez, María E; Núñez, Sonia G; Contreras, Verónica M; Castro, Bertha E

    2011-10-01

    INTRODUCCIÓN En El Salvador, la enfermedad renal crónica terminal es la causa principal de muerte hospitalaria en adultos, la segunda causa de muerte en los hombres y la quinta causa principal de muerte entre adultos de ambos sexos en la población general. OBJETIVO Identificar los factores de riesgo de la enfermedad renal crónica y los marcadores de daño renovascular en orina, medir la función renal y caracterizar la prevalencia de enfermedad renal crónica en personas X18 años de edad en la región del Bajo Lempa en El Salvador. METODOS Se realizó un estudio epidemiológico transversal y analítico de la enfermedad renal crónica y los factores de riesgo asociados en individuos con edades X18 años por medio de pesquisa activa en la Región del Bajo Lempa, una zona costera rural en El Salvador. Se efectuaron visitas casa por casa y consultas médicas. Se recolectaron datos epidemiológicos y clínicos que incluían: historia clínica personal y familiar para la enfermedad; factores de riesgo biológicos, de conducta, sociales y ambientales; mediciones físicas; análisis de orina buscando marcadores de daño renovascular y exámenes de sangre (creatinina y glucosa en suero, lipidograma). La tasa de filtración glomerular se calculó usando la fórmula de MDRD (sigla en inglés de Modificación de la Dieta en la Enfermedad Renal). La confirmación de casos de enfermedad renal crónica se realizó en un período de tres meses. Se utilizó la regresión logística múltiple para analizar los datos. RESULTADOS Se estudiaron un total de 375 familias y 775 individuos (343 hombres, 432 mujeres), el 88,3% del total de la población residente en la región. Se observó una elevada prevalencia de factores de riesgo: diabetes mellitus en 10,3%; hipertensión en 16,9%; antecedentes familiares de enfermedad renal crónica en 21,6%; dislipidemias en 63,1%; sobrepeso en 34%; obesidad en 22,4%; síndrome metabólico en 28,8%; uso de medicamentos anti-inZ amatorios no

  12. Soil characterization in urban areas of the Bajo Segura Basin (Southeast Spain) using H/V, F-K and ESAC methods

    NASA Astrophysics Data System (ADS)

    Rosa-Cintas, S.; Galiana-Merino, J. J.; Molina-Palacios, S.; Rosa-Herranz, J.; García-Fernández, M.; Jiménez, M. J.

    2011-11-01

    Bajo Segura Basin, placed in the south of Alicante province (southeast Spain), is a region of moderate seismicity, which presents frequent seismic episodes. This region, as the rest of south-eastern part of Spain, is growing both economically and demographically. Hence, the presence of soft soils in a seismic region where many towns and villages are placed shows the importance of an adequate characterization of the site effects study in this area. The present work investigates the use of noise measurements for soil characterization by the application of H/V method and array techniques: extended spatial autocorrelation (ESAC) and frequency-wave number (F-K) in three urban areas of the Bajo Segura Basin. The application of these methods will help us to estimate the resonance frequencies, as well as shear-wave velocity profiles, having a better understanding of the sediment depth and site effects phenomena at the studied places. The estimated velocity profiles are used to model the fundamental mode Rayleigh wave ellipticity curves and the S-wave site transfer functions. Finally, the correlation between this curves and the experimental H/V analysis has allowed us a better assessment of the site response in the studied areas.

  13. Early Pliocene transgressive coastal lags (Bajo Segura Basin, Spain): a marker of the flooding after the Messinian salinity crisis [rapid communication

    NASA Astrophysics Data System (ADS)

    Caracuel, Jesús E.; Soria, Jesús M.; Yébenes, Alfonso

    2004-07-01

    The Messinian salinity crisis is recorded on the northern margin of the Bajo Segura Basin by lacustrine and fluvial deposits coeval to the evaporites that precipitated in the basin's central areas. These syn-evaporitic Messinian deposits are bounded at the top by an erosional surface caused by a fall in base level (end-Messinian unconformity) on which an early Pliocene sequence is located. The latter begins with a coastal lag, consisting of oncoliths and carbonate clasts intensely bored and encrusted by lithobionts, that records the installation of beach environments at the beginning of the Pliocene transgression. A succession of pelagic marls rich in planktonic and benthic foraminifers lies on this basal lag and indicates the complete marine flooding of the basin and the definitive conclusion of the salinity crisis.

  14. [Outbreaks of human rabies transmitted by vampire bats in Alto Baudó and Bajo Baudó municipalities, department of chocó, Colombia, 2004-2005].

    PubMed

    Valderrama, Jessika; García, Ingrid; Figueroa, Germán; Rico, Edilberto; Sanabria, Juliana; Rocha, Nicolás; Parra, Edgar; Saad, Cecilia; Páez, Andrés

    2006-09-01

    During months May to July 2004, a rabies outbreak in the Embera community of Birrinchao, in the Purricha river basin department of Choc6 was reported with 14 human deaths. Another rabies outbreak was reported in January 2005 in the black communities of Pató and Nauca in the neighboring municipality of Alto Baudó with 3 human deaths. To describe the largest outbreaks of human rabies transmitted by vampire bats reported in Colombia to date. To describe the diagnostic laboratory techniques used, and the activities undertaken for the control of rabies in the area. To discuss the epidemiologic significance and public health implications of these rabies outbreaks. Rabies diagnosis was achieved by direct immunofluorescence, inoculation of mice and immunohistochemistry. Typing of the virus was achieved by indirect immunofluorescence using monoclonal antibodies. Rabies control activities were undertaken in Bajo Baudó consisting in a population census, human vaccination and application of antirabies sera, vaccination of dogs and cats, and application of anticoagulant to bats. Four human cases were confirmed as positive for rabies in both rabies outbreaks. Another 13 rabies cases in humans were inferred by strong epidemiological links. Rabies antigenic variant 3 was identified in the samples studied. Rabies control activities were conducted for a human rabies outbreak caused by vampire bats. The human rabies outbreak in Bajo Baudó has been the largest reported in Colombia. It was caused by vampire bats, showing that these animals are a threat for human health. The implementation of control strategies for this kind of epizootic outbreaks is needed in South America. It remains unknown whether there is a link between this outbreak and one reported 6 months later in the neighboring municipality of Alto Baudó.

  15. Mechanisms of aggradation in fluvial systems influenced by explosive volcanism: An example from the Upper Cretaceous Bajo Barreal Formation, San Jorge Basin, Argentina

    NASA Astrophysics Data System (ADS)

    Umazano, Aldo M.; Bellosi, Eduardo S.; Visconti, Graciela; Melchor, Ricardo N.

    2008-01-01

    The Late Cretaceous succession of the San Jorge Basin (Patagonia, Argentina) records different continental settings that interacted with explosive volcanism derived from a volcanic arc located in the western part of Patagonia. This paper discusses the contrasting aggradational mechanisms in fluvial systems strongly influenced by explosive volcanism which took place during sedimentation of the Bajo Barreal Formation. During deposition of the lower member of the unit, common ash-fall events and scarce sandy debris-flows occurred, indicating syn-eruptive conditions. However, the record of primary pyroclastic deposits is scarce because they were reworked by river flows. The sandy fluvial channels were braided and show evidence of important variations in water discharge. The overbank flows (sheet-floods) represent the main aggradational mechanism of the floodplain. In places, subordinate crevasse-splays and shallow lakes also contributed to the floodplain aggradation. In contrast, deposition of the upper member occurred in a fluvial-aeolian setting without input of primary volcaniclastic detritus, indicating inter-eruptive conditions. The fluvial channels were also braided and flowed across low-relief floodplains that mainly aggraded by deposition of silt-sized sediments of aeolian origin (loess) and, secondarily by sheet-floods. The Bajo Barreal Formation differs from the classic model of syn-eruptive and inter-eruptive depositional conditions in the presence of a braided fluvial pattern during inter-eruptive periods, at least at one locality. This braided fluvial pattern is attributed to the high input of fine-grained pyroclastic material that composes the loessic sediments.

  16. Crustal shortening, exhumation, and strain localization in a collisional orogen: The Bajo Pequeño Shear Zone, Sierra de Pie de Palo, Argentina

    NASA Astrophysics Data System (ADS)

    Garber, Joshua M.; Roeske, Sarah M.; Warren, Jessica; Mulcahy, Sean R.; McClelland, William C.; Austin, Lauren J.; Renne, Paul R.; Vujovich, Graciela I.

    2014-07-01

    The Bajo Pequeño Shear Zone (BPSZ) is a lower-crustal shear zone that records shortening and exhumation associated with the establishment of a new plate boundary, and its placement in a regional structural context suggests that local- to regional-scale strain localization occurred with progressive deformation. A kilometer-scale field and analytical cross section through the ~80 m thick BPSZ and its adjacent rocks indicates an early Devonian (405-400 Ma) phase of deformation on the western margin of Gondwanan continental crust. The earliest stages of the BPSZ, recorded by metamorphic and microstructural data, involved thrusting of a hotter orthogneiss over a relatively cool pelitic unit, which resulted in footwall garnet growth and reset footwall white mica 40Ar/39Ar ages in proximity to the shear zone. Later stages of BPSZ activity, as recorded by additional microstructures and quartz c-axis opening angles, were characterized by strain localization to the center of the shear zone coincident with cooling and exhumation. These and other data suggest that significant regional tectonism persisted in the Famatinian orogenic system for 60-70 million years after one microplate collision (the Precordillera) but ceased 5-10 million years prior to another (Chilenia). A survey of other synchronous structures shows that strain was accommodated on progressively narrower structures with time, indicating a regional pattern of strain localization and broad thermal relaxation as the Precordillera collision evolved.

  17. Multimillion year thermal history of a porphyry copper deposit: application of U-Pb, 40Ar/39Ar and (U-Th)/He chronometers, Bajo de la Alumbrera copper-gold deposit, Argentina

    NASA Astrophysics Data System (ADS)

    Harris, Anthony C.; Dunlap, W. James; Reiners, Peter W.; Allen, Charlotte M.; Cooke, David R.; White, Noel C.; Campbell, Ian H.; Golding, Suzanne D.

    2008-03-01

    Application of multiple chronometers (including U-Pb and 40Ar/39Ar geochronology and zircon and apatite (U-Th)/He thermochronology) to porphyry intrusions at the Bajo de la Alumbrera porphyry copper-gold deposit, Argentina, reveals a complex history of reheating that spans millions of years. Previous U-Pb geochronology, combined with our new 40Ar/39Ar data, shows that the multiple porphyritic intrusions at Bajo de la Alumbrera were emplaced during two episodes, the first at about 8.0 Ma (P2 and associated porphyries) and the second about a million years later (Early and Late P3 porphyries). Complex overprinting alteration events have obscured the earliest hydrothermal history of the deposit. By contrast, 40Ar/39Ar data reveal the close temporal relationship of ore-bearing potassic alteration assemblages (7.12 ± 0.13 Ma; biotite) to the emplacement of the P3 intrusions. Consistent with low closure temperatures, younger ages have been determined for associated hydrothermal alkali feldspar (6.82 ± 0.05 Ma and 6.64 ± 0.09 Ma). The temperature-sensitive Ar data also record an unexpected prolonged cooling history (to below 200°C) extending to 5.9 Ma. Our data suggest that the Bajo de la Alumbrera system underwent protracted cooling, after the collapse of the main hydrothermal system, or that one or more low-temperature (~100-200°C) reheating events occurred after emplacement of the porphyritic intrusions at Bajo de la Alumbrera. These have been constrained in part by our new 40Ar/39Ar data (including multidomain diffusion modeling) and (U-Th)/He ages. Single-grain (U-Th)/He ages ( n = 5) for phenocrystic zircon from P2 and P3 intrusive phases bracket these thermal events to between 6.9 (youngest crystallization of intrusion) and 5.1 Ma. Multidomain modeling of alkali feldspar data (from both igneous and hydrothermal crystals) is consistent with the deposit cooling rapidly from magmatic temperatures to below about 300°C, with a more protracted history down to 150

  18. Improvement of isotope-based climate reconstructions in Patagonia through a better understanding of climate influences on isotopic fractionation in tree rings

    NASA Astrophysics Data System (ADS)

    Lavergne, Aliénor; Daux, Valérie; Villalba, Ricardo; Pierre, Monique; Stievenard, Michel; Srur, Ana Marina

    2017-02-01

    Very few studies of stable isotopes exist across the Andes in South America. This study is the first presenting annually resolved chronologies of both δ18 O and δ13 C in Nothofagus pumilio and Fitzroya cupressoides trees from Northern Patagonia. Interannual variability in δ18 O and δ13 C was assessed over the period 1952-2011. Based on these chronologies, we determined the primary climatic controls on stable isotopes and tree physiological responses to changes in atmospheric CO2 concentrations (ca), temperature and humidity. Changes in specific intrinsic water use efficiency (iWUE) were inferred from variations in δ13 C whereas the effects of CO2 increase on stomatal conductance were explored using δ18 O. Over the 60-year period, iWUE increased significantly (by ca. 25%) in coincidence with the rise of ca. The two species appear to have different strategies of gas-exchange. Whereas iWUE variations were likely driven by both stomatal conductance and photosynthetic assimilation rates in F. cupressoides, they were largely related to stomatal conductance in N. pumilio. After removing the low-frequency trends related to increasing ca, significant relationships between δ13 C and summer temperatures were recorded for both species. However, δ13 C variations in F. cupressoides were more strongly influenced by summer temperatures than in N. pumilio. Our results advocate for an indirect effect of summer temperatures on stable isotope ratios, which is mostly influenced by sunlight radiation in F. cupressoides and relative humidity/soil moisture in N. pumilio. δ13 C variations in F. cupressoides were spatially correlated to a large area south of 35°S in southern South America. These promising results encourage the use of δ13 C variations in F. cupressoides for reconstructing past variations in temperature and large-scale circulation indexes such as the Southern Annular Mode (SAM) in the Southern Hemisphere.

  19. The Messinian early Pliocene stratigraphic record in the southern Bajo Segura Basin (Betic Cordillera, Spain): Implications for the Mediterranean salinity crisis

    NASA Astrophysics Data System (ADS)

    Soria, Jesús M.; Caracuel, Jesús E.; Corbí, Hugo; Dinarès-Turell, Jaume; Lancis, Carlos; Tent-Manclús, José E.; Viseras, César; Yébenes, Alfonso

    2008-01-01

    The analysis of the Messinian and Pliocene stratigraphy of the southern Bajo Segura Basin (Betic Cordillera, Spain) has revealed three highstand sedimentary phases (Messinian I, Messinian II, and Pliocene) bounded by two lowstand erosional surfaces (intra-Messinian and end-Messinian unconformities). The Messinian I highstand phase is characterized by the progradation of coastal and shallow marine sandstones (La Virgen Fm) over slope and pelagic-basin marls (Torremendo Fm). After this first phase, a fall in sea level brought about the intra-Messinian unconformity, a subaerial erosional surface with local accumulations of karstic breccias and caliche-like carbonate crusts. The Messinian II highstand phase is represented by sandy beaches and muddy lagoons (Garruchal Fm) correlative with shallow marine evaporites (San Miguel Fm); this second phase records the intra-Messinian reflooding of the basin, which characterizes the salinity crisis in the marginal basins of the Mediterranean. A new sea-level fall resulted in the end-Messinian unconformity, of which the most significant feature is the presence of a broad palaeovalley, c. 200 m deep, which, along its course, completely eroded the deposits of the Messinian II phase and part of the deposits of the Messinian I phase. The Pliocene highstand phase begins with coastal and shallow marine conglomerates and sandstones (La Pedrera Fm) which fill the deep part of the above-mentioned palaeovalley. These bottom deposits evolved gradually upwards towards pelagic marls (Hurchillo Fm), over which shallow marine and coastal sandstones prograded (Rojales Fm). This third phase records the flooding of the basin at the beginning of the Pliocene, when the salinity crisis ended in the marginal basins of the Mediterranean. The combination of calcareous nannoplankton biostratigraphy and magnetostratigraphy has confirmed that both the end of the sedimentation of the Messinian I phase, as well as the two lowstand erosional surfaces (intra

  20. Structure and potential seismogenic and tsunamigenic sources of the offshore Bajo Segura fault zone, SE Iberian Peninsula (Mediterranean Sea): Preliminary results

    NASA Astrophysics Data System (ADS)

    Perea, H.; Gràcia, E.; Bartolomé, R.; Lo Iacono, C.; Masana, E.; Event-Shelf Team

    2009-04-01

    The present-day crustal deformation of the SE Iberian margin is driven mainly by the NW-SE convergence (4-5 mm/yr) between the African and Eurasian plates. This convergence is accommodated over a wide deformation zone with significant seismic activity south of the Iberian Peninsula. The Neogene and Quaternary faulting activity in the SE Iberian Margin is dominated by a large left-lateral strike-slip system of sigmoid geometry referred to as the Eastern Betic Shear Zone (EBSZ), stretching over more than 450 km from Alacant to Almería. The northern terminal splays of the EBSZ correspond to the Bajo Segura fault zone (BSFZ) that extends further into the Mediterranean Sea. This fault zone shows an important instrumental seismic activity characterized by small to moderate earthquakes. Even though, moderate to large historical earthquakes have affected the zone, being the Torrevieja earthquake (1829; IMSK=X) the largest. The onshore area of the BSFZ has been extensively studied and it is characterized by active structures (faults and folds) displaying a transpressive behavior since the Plio-Pleistocene and resulting in positive relieves and subsiding zones. However, the offshore area shows an almost complete lack of information from the tectonic point of view. Recently, the marine geophysical cruise EVENT-SHELF was carried out in September 2008 onboard the Spanish RV Garcia del Cid. The main goal was to map the seafloor ruptures and the sub-seafloor structures of the offshore area of BSFZ using swath bathymetry and high-resolution seismics (Spaker GeoSpark 6kJ). A total of 10 regional profiles were acquired along and across the fault zone. The preliminary results from the analysis of the acoustic and seismic data show that the main structures observed onshore have their continuation offshore, and that some of the faults and folds related to the BSFZ are active. The carefully study and processing of these data will allow us to localize the present active structures

  1. Asháninka medicinal plants: a case study from the native community of Bajo Quimiriki, Junín, Peru

    PubMed Central

    2010-01-01

    Background The Asháninka Native Community Bajo Quimiriki, District Pichanaki, Junín, Peru, is located only 4 km from a larger urban area and is dissected by a major road. Therefore the loss of traditional knowledge is a main concern of the local headman and inhabitants. The present study assesses the state of traditional medicinal plant knowledge in the community and compares the local pharmacopoeia with the one from a related ethnic group. Methods Fieldwork was conducted between July and September 2007. Data were collected through semi-structured interviews, collection of medicinal plants in the homegardens, forest walks, a walk along the river banks, participant observation, informal conversation, cross check through voucher specimens and a focus group interview with children. Results Four-hundred and two medicinal plants, mainly herbs, were indicated by the informants. The most important families in terms of taxa were Asteraceae, Araceae, Rubiaceae, Euphorbiaceae, Solanaceae and Piperaceae. Eighty-four percent of the medicinal plants were wild and 63% were collected from the forest. Exotics accounted to only 2% of the medicinal plants. Problems related to the dermal system, digestive system, and cultural belief system represented 57% of all the medicinal applications. Some traditional healers received non-indigenous customers, using their knowledge as a source of income. Age and gender were significantly correlated to medicinal plant knowledge. Children knew the medicinal plants almost exclusively by their Spanish names. Sixteen percent of the medicinal plants found in this community were also reported among the Yanesha of the Pasco Region. Conclusions Despite the vicinity to a city, knowledge on medicinal plants and cultural beliefs are still abundant in this Asháninka Native Community and the medicinal plants are still available in the surroundings. Nevertheless, the use of Spanish names for the medicinal plants and the shift of healing practices towards a

  2. From a long-lived upper-crustal magma chamber to rapid porphyry copper emplacement: Reading the geochemistry of zircon crystals at Bajo de la Alumbrera (NW Argentina)

    NASA Astrophysics Data System (ADS)

    Buret, Yannick; von Quadt, Albrecht; Heinrich, Christoph; Selby, David; Wälle, Markus; Peytcheva, Irena

    2016-09-01

    The formation of world class porphyry copper deposits reflect magmatic processes that take place in a deeper and much larger underlying magmatic system, which provides the source of porphyry magmas, as well as metal and sulphur-charged mineralising fluids. Reading the geochemical record of this large magmatic source region, as well as constraining the time-scales for creating a much smaller porphyry copper deposit, are critical in order to fully understand and quantify the processes that lead to metal concentration within these valuable mineral deposits. This study focuses on the Bajo de la Alumbrera porphyry copper deposit in Northwest Argentina. The deposit is centred on a dacitic porphyry intrusive stock that was mineralised by several pulses of porphyry magma emplacement and hydrothermal fluid injections. To constrain the duration of ore formation, we dated zircons from four porphyry intrusions, including pre-, syn- and post-mineralisation porphyries based on intersection relations between successive intrusion and vein generations, using high precision CA-ID-TIMS. Based on the youngest assemblages of zircon grains, which overlap within analytical error, all four intrusions were emplaced within 29 ka, which places an upper limit on the total duration of hydrothermal mineralisation. Re/Os dating of hydrothermal molybdenite fully overlaps with this high-precision age bracket. However, all four porphyries contain zircon antecrysts which record protracted zircon crystallisation during the ∼200 ka preceding the emplacement of the porphyries. Zircon trace element variations, Ti-in-zircon temperatures, and Hf isotopic compositions indicate that the four porphyry magmas record a common geochemical and thermal history, and that the four intrusions were derived from the same upper-crustal magma chamber. Trace element zoning within single zircon crystals confirms a fractional crystallisation trend dominated by titanite and apatite crystallisation. However, zircon

  3. The nasty neighbour in the striped mouse (Rhabdomys pumilio) steals paternity and elicits aggression

    PubMed Central

    2010-01-01

    Background Territoriality functions to monopolize access to resources including mates, but is costly in terms of energy and time investment. Some species reduce these costs by being less aggressive towards their neighbours than towards unfamiliar strangers, the so called dear enemy phenomenon. However, in other species individuals are more, not less aggressive towards their neighbours. It has been hypothesised that this is due to the fact that neighbours can impose a greater threat than strangers, but this has not been tested previously. Results We tested aggression in wild group-living male striped mice in a neutral test arena and demonstrate that breeders are more aggressive than non-breeding philopatrics, and that more aggression occurs during the breeding than during the non-breeding season. Male breeders were significantly more aggressive towards their neighbours than towards strangers, leading to the prediction that neighbours are the most important competitors for paternity. Using a molecular parentage analysis we show that 28% of offspring are sired by neighbouring males and only 7% by strangers. Conclusions We conclude that in male striped mice the main function of male aggression is defending paternity against their territorial neighbours. PMID:20573184

  4. A 3’UTR Pumilio binding element directs translational activation in olfactory sensory neurons

    PubMed Central

    Kaye, Julia A.; Rose, Natalie C.; Goldsworthy, Brett; Goga, Andrei; L'Etoile, Noelle D.

    2014-01-01

    Summary Prolonged stimulation leads to specific and stable changes in an animal’s behavior. In interneurons, this plasticity requires spatial and temporal control of neuronal protein synthesis. Whether such translational control occurs in sensory neurons is not known. Adaptation of the AWC olfactory sensory neurons of C. elegans requires the cGMP-dependent protein kinase EGL-4. Here we show that the PUF FBF-1 is required in the adult AWC for adaptation and in the odor-adapted animal, increases translation from the egl-4 3’ UTR. Further, the PUF protein may localize translation near the sensory cilia and cell body. Although the RNA-binding PUF proteins have been shown to promote plasticity in development by temporally and spatially repressing translation; this work reveals that in the adult nervous system, they can work in a different way to promote experience-dependent plasticity by activating translation in response to environmental stimulation. PMID:19146813

  5. Nutritional manipulation of adult female Orius pumilio (Hemiptera: Anthocoridae) enhances initial predatory performance

    USDA-ARS?s Scientific Manuscript database

    Commercial shipments of Orius insidiosus Say (Hemiptera:Anthocoridae) commonly include water and protein, the latter typically supplied by eggs from a moth such as Ephestia kuehniella Zeller. To determine whether alternative dietary conditions for young adult females might improve predation, O. in...

  6. Ecology of cultivable yeasts in pristine forests in northern Patagonia (Argentina) influenced by different environmental factors.

    PubMed

    Mestre, María Cecilia; Fontenla, Sonia; Rosa, Carlos A

    2014-06-01

    Environmental factors influencing the occurrence and community structure of soil yeasts in forests are not well studied. There are few studies dedicated to Southern Hemisphere soil yeasts populations and even fewer focused on temperate forests influenced by volcanic activity. The present work aimed to study the ecology of soil yeast communities from pristine forests influenced by different environmental factors (precipitation, physicochemical properties of soil, tree species, soil region, and season). The survey was performed in 4 northern Patagonian forests: 2 dominated by Nothofagus pumilio and 2 by Nothofagus antarctica. Yeast communities were described with ecological indices and species accumulation curves, and their association with environmental characteristics was assessed using multivariate analysis. Each forest site showed a particular arrangement of species as a result of environmental characteristics, such as dominant plant species, nutrient availability, and climatic characteristics. Cryptococcus podzolicus was most frequently isolated in nutrient-rich soils, Trichosporon porosum dominated cold mountain forests with low nutrient and water availability in soil, and capsulated yeasts such as Cryptococcus phenolicus dominated forest sites with low precipitation. The present work suggests that environmental factors affecting yeast communities may not be the current soil characteristics but the result of complex interactions of factors including natural disturbances like volcanic activity.

  7. Dendroecological analysis of a Fitzroya cupressoides and a Nothofagus nitida stand in the Cordillera Pelada, Chile

    Treesearch

    Margaret S. Devall; Bernard R. Parresol; Juan J. Armesto

    1998-01-01

    Lumbering of Fitzroya cupressoides in Chile began in 1599 and continued until 1976, when the species was declared a national monument and cutting of live trees was prohibited. Today, F. cupressoides is threatened; many of the remaining stands in the coastal range appear to be declining, with a predominance of standing dead stems and patchy, sparse regeneration. The...

  8. The phylogenetic position of poroid Hymenochaetaceae (Hymenochaetales, Basidiomycota) from Patagonia, Argentina.

    PubMed

    Rajchenberg, Mario; Pildain, María Belén; Bianchinotti, María V; Barroetaveña, Carolina

    2015-01-01

    Six poroid Hymenochaetaceae from Patagonia, Argentina, were studied phylogenetically with nuc rDNA internal transcribed spacer (ITS) and partial 28S rDNA sequences, together with morphological data. Two new genera and a new species are introduced as well as two new combinations proposed. Arambarria destruens gen. et sp. nov. is proposed for a taxon fruiting on fallen or standing, dead Diostea juncea and Lomatia hirsuta and previously recorded erroneously as Inocutis jamaicensis; it is distinguished by annual, effused to effused-reflexed basidiomes forming pilei, a monomitic hyphal system, thick-walled and yellowish basidiospores (brownish chestnut in potassium hydroxide solution), lack of a granular core in the context and lack of setoid elements. Nothophellinus gen. nov. is proposed to accommodate Phellinus andinopatagonicus, the main white wood-rotting polypore of standing Nothofagus pumilio and also an important wood-decayer of other Nothofagus species from southern Argentina and Chile. It is morphologically similar to Phellopilus (type species P. nigrolimitatus) but differs by lacking setae. The new combinations Pseudoinonotus crustosus and Phellinopsis andina are proposed for Inonotus crustosus and Phellinus andinus, respectively. Phellinus livescens, which decays the sapwood of several standing Nothofagus species, is closely related to Phellinus uncisetus, a Neotropical species related to Fomitiporia; for the time being P. livescens is retained in Phellinus sensu lato. An unidentified taxon responsible for a white heart-rot in living Austrocedrus chilensis grouped with Phellinus caryophyllii and Fulvifomes inermis, but its generic affinities remain ambiguous. Transmission electron microscopy studies confirm this unidentified taxon has an imperforate parenthesome, which is typical of the Hymenochaetaceae. © 2015 by The Mycological Society of America.

  9. Similar variation in carbon storage between deciduous and evergreen treeline species across elevational gradients

    PubMed Central

    Fajardo, Alex; Piper, Frida I.; Hoch, Günter

    2013-01-01

    Background and Aims The most plausible explanation for treeline formation so far is provided by the growth limitation hypothesis (GLH), which proposes that carbon sinks are more restricted by low temperatures than by carbon sources. Evidence supporting the GLH has been strong in evergreen, but less and weaker in deciduous treeline species. Here a test is made of the GLH in deciduous–evergreen mixed species forests across elevational gradients, with the hypothesis that deciduous treeline species show a different carbon storage trend from that shown by evergreen species across elevations. Methods Tree growth and concentrations of non-structural carbohydrates (NSCs) in foliage, branch sapwood and stem sapwood tissues were measured at four elevations in six deciduous–evergreen treeline ecotones (including treeline) in the southern Andes of Chile (40°S, Nothofagus pumilio and Nothofagus betuloides; 46°S, Nothofagus pumilio and Pinus sylvestris) and in the Swiss Alps (46°N, Larix decidua and Pinus cembra). Key Results Tree growth (basal area increment) decreased with elevation for all species. Regardless of foliar habit, NSCs did not deplete across elevations, indicating no shortage of carbon storage in any of the investigated tissues. Rather, NSCs increased significantly with elevation in leaves (P < 0·001) and branch sapwood (P = 0·012) tissues. Deciduous species showed significantly higher NSCs than evergreens for all tissues; on average, the former had 11 % (leaves), 158 % (branch) and 103 % (sapwood) significantly (P < 0·001) higher NSCs than the latter. Finally, deciduous species had higher NSC (particularly starch) increases with elevation than evergreens for stem sapwood, but the opposite was true for leaves and branch sapwood. Conclusions Considering the observed decrease in tree growth and increase in NSCs with elevation, it is concluded that both deciduous and evergreen treeline species are sink limited when faced with decreasing temperatures

  10. Uso de la punción lumbar en la evaluación de sepsis neonatal tardía en recién nacidos de bajo peso al nacer

    PubMed Central

    Zea-Vera, A; Turín, CG; Rueda, MS; Guillén-Pinto, D; Medina-Alva, P; Tori, A; Rivas, M; Zegarra, J; Castañeda, A; Cam, L; Ochoa, TJ

    2017-01-01

    RESUMEN El objetivo de este estudio fue analizar el uso de la punción lumbar (PL) en las sospechas de sepsis neonatal tardía. Se recomienda realizar una PL en la evaluación de toda sospecha de sepsis neonatal tardía. Se utilizó una cohorte de 414 neonatos con peso al nacer <2000g en tres hospitales de Lima. Se realizó la PL en 45/214 (21,0%) sospechas de sepsis y en 13/48 (27,1%) sepsis confirmadas por hemocultivo. Se diagnosticó meningitis en 8/214 (3,7%) sospechas y en 8/45 (17,5%) episodios en los que se realizó la PL. El tiempo de tratamiento de los episodios sin PL fue similar a los episodios de sepsis con meningitis descartada y menor a los episodios de meningitis. El uso de la PL es bajo, lo que puede resultar en meningitis no diagnosticadas y tratadas inadecuadamente. Es necesario reforzar la importancia de la PL en la evaluación de sepsis neonatal. PMID:27656928

  11. Histology and Ultrastructure of Transitional Changes in Skin Morphology in the Juvenile and Adult Four-Striped Mouse (Rhabdomys pumilio)

    PubMed Central

    Stewart, Eranée; Ajao, Moyosore Salihu

    2013-01-01

    The four-striped mouse has a grey to brown coloured coat with four characteristic dark stripes interspersed with three lighter stripes running along its back. The histological differences in the skin of the juvenile and adult mouse were investigated by Haematoxylin and Eosin and Masson Trichrome staining, while melanocytes in the skin were studied through melanin-specific Ferro-ferricyanide staining. The ultrastructure of the juvenile skin, hair follicles, and melanocytes was also explored. In both the juvenile and adult four-striped mouse, pigment-containing cells were observed in the dermis and were homogeneously dispersed throughout this layer. Apart from these cells, the histology of the skin of the adult four-striped mouse was similar to normal mammalian skin. In the juvenile four-striped mouse, abundant hair follicles of varying sizes were observed in the dermis and hypodermis, while hair follicles of similar size were only present in the dermis of adult four-striped mouse. Ultrastructural analysis of juvenile hair follicles revealed that the arrangement and differentiation of cellular layers were typical of a mammal. This study therefore provides unique transition pattern in the four-striped mouse skin morphology different from the textbook description of the normal mammalian skin. PMID:24288469

  12. Histology and ultrastructure of transitional changes in skin morphology in the juvenile and adult four-striped mouse (Rhabdomys pumilio).

    PubMed

    Stewart, Eranée; Ajao, Moyosore Salihu; Ihunwo, Amadi Ogonda

    2013-01-01

    The four-striped mouse has a grey to brown coloured coat with four characteristic dark stripes interspersed with three lighter stripes running along its back. The histological differences in the skin of the juvenile and adult mouse were investigated by Haematoxylin and Eosin and Masson Trichrome staining, while melanocytes in the skin were studied through melanin-specific Ferro-ferricyanide staining. The ultrastructure of the juvenile skin, hair follicles, and melanocytes was also explored. In both the juvenile and adult four-striped mouse, pigment-containing cells were observed in the dermis and were homogeneously dispersed throughout this layer. Apart from these cells, the histology of the skin of the adult four-striped mouse was similar to normal mammalian skin. In the juvenile four-striped mouse, abundant hair follicles of varying sizes were observed in the dermis and hypodermis, while hair follicles of similar size were only present in the dermis of adult four-striped mouse. Ultrastructural analysis of juvenile hair follicles revealed that the arrangement and differentiation of cellular layers were typical of a mammal. This study therefore provides unique transition pattern in the four-striped mouse skin morphology different from the textbook description of the normal mammalian skin.

  13. North Patagonia climate over the last millennium inferred from variations in tree-ring width and isotopic composition

    NASA Astrophysics Data System (ADS)

    Lavergne, Aliénor; Villalba, Ricardo; Daux, Valérie

    2014-05-01

    To disentangle natural variability from man-induced climate changes, current climatic trends should be placed in a longer perspective. Tree-rings provide a wealth of information on past climates with high-resolution records covering up to thousands years. Recent tree-ring studies have highlighted the divergence phenomenon in Northern Hemisphere forests. At some temperature-limited northern sites, tree growth responses to climate during recent decades have changed, raising concerns about the quality of historical climate reconstructions based on tree-ring widths. This shift in the eco-physiological response of trees to climate has not yet been documented in the Southern Hemisphere. The aim of this study is to present the tree-ring evolution over the last centuries in northern Patagonia (southern South America; 41° 10'S-71° 50'W) in order to assess 1) divergence in tree-growth response to climate in recent decades, and 2) the potential of tree-ring parameters (width and δ18O) to reconstruct temperature and atmospheric circulation patterns such as the Southern Annular Mode (SAM). Based on quality and extent, instrumental temperature records across North Patagonia (39° -41° S) were selected for comparison with tree-ring records. Detection and correction of series inhomogeneities were conducted using HOMER software. A set of homogenized temperature data was developed for the period 1901-2013. Increment-borer samples from Fitzroya cupressoides and Nothofagus pumilio were collected along the regional precipitation gradient from the wet Valdivian rainforest to the mesic Patagonian forests during the austral summer of 2013. Six sampling sites (2 for Fitzroya, 4 for Nothofagus) along the gradient were established to maximize differences in tree-growth responses to climate and to assess the effect of precipitation on the responses. More than 500 cores were cross-dated, detrended and indexed. Composite tree-ring index (TRI) chronologies of F. cupressoides and N. pumilio

  14. Environmental and genetic control of insect abundance and herbivory along a forest elevational gradient.

    PubMed

    Garibaldi, Lucas A; Kitzberger, Thomas; Chaneton, Enrique J

    2011-09-01

    Environmental conditions and plant genotype may influence insect herbivory along elevational gradients. Plant damage would decrease with elevation as temperature declines to suboptimal levels for insects. However, host plants at higher elevations may exhibit traits that either reduce or enhance leaf quality to insects, with uncertain net effects on herbivory. We examined folivory, insect abundance and leaf traits along six replicated elevational ranges in Nothofagus pumilio forests of the northern Patagonian Andes, Argentina. We also conducted a reciprocal transplant experiment between low- and high-elevation sites to test the extent of environmental and plant genetic control on insect abundance and folivory. We found that insect abundance, leaf size and specific leaf area decreased, whereas foliar phosphorous content increased, from low-, through mid- to high-elevation sites. Path analysis indicated that changes in both insect abundance and leaf traits were important in reducing folivory with increasing elevation and decreasing mean temperature. At both planting sites, plants from a low-elevation origin experienced higher damage and supported greater insect loads than plants from a high-elevation origin. The differences in leaf damage between sites were twofold larger than those between plant origins, suggesting that local environment was more important than host genotype in explaining folivory patterns. Different folivore guilds exhibited qualitatively similar responses to elevation. Our results suggest an increase in insect folivory on high-elevation N. pumilio forests under future climate warming scenarios. However, in the short-term, folivory increases might be smaller than expected from insect abundance only because at high elevations herbivores would encounter more resistant tree genotypes.

  15. Assessment of land influence on a high-latitude marine coastal system: Tierra del Fuego, southernmost Argentina.

    PubMed

    Amin, Oscar; Comoglio, Laura; Spetter, Carla; Duarte, Claudia; Asteasuain, Raúl; Freije, Rubén Hugo; Marcovecchio, Jorge

    2011-04-01

    The study deals with the determination of physico-chemical parameters, inorganic nutrients, particulate organic matter, and photosynthetic pigments on a monthly basis during an annual cycle from nine sampling sites of the coastal zone of a high-latitude ecosystem (Tierra del Fuego, Argentina). Nitrites and phosphates concentrations were similar to other systems of the south Atlantic coast (median, 0.30 and 1.02 μM, respectively), while nitrates were higher in all sampling periods (median, 45.37 μM), and silicates were significantly smaller (median, 7.76 μM). Chlorophyll a and phaeopigments have shown median values of 0.38 and 0.85 mg m(-3), respectively, while saturated values of dissolved oxygen were recorded throughout the study. The analysis reflected that nutrient enrichment seems to be linked to an anthropogenic source, the presence of peatlands areas, and a sink of Nothofagus pumilio woods. The area could be characterized in three zones related to (1) high urban influence, (2) natural inputs of freshwater, and (3) mixed inputs coming from moderate urban impacts.

  16. Intra and Inter-Population Morphological Variation of Shape and Size of the Chilean Magnificent Beetle, Ceroglossus chilensis in the Baker River Basin, Chilean Patagonia

    PubMed Central

    Benítez, Hugo A.; Briones, Raúl; Jerez, Viviane

    2011-01-01

    The alteration of habitat generates different degrees of stress in insects. It has been suggested that the degrees of phenotypic disturbances reflect the ability of an individual to overcome the effects of stress. The Baker River Basin in the Aysén Region, Chilean Patagonia has a very fragmented landscape, due to the destruction of the native forest and the use of land for agriculture and animal husbandry. This alteration should generate different degrees of disturbances in the insect communities, whose effects may be quantified by geometric morphometric tools. We analyzed morphological differences in 244 males and 133 females of the the Chilean magnificent beetle, Ceroglossus chilensis (Eschscholtz) (Coleoptera: Carabidae) collected in January, 2007, in mixed forests of Nothofagus dombeyi Mirbel (Ørsted) (Fagales: Nothofagaceae) and N. nitida Hofmus and in Second-growth forest of N. pumilio (Poepp. & Endl.) Krasser. Males were generally wider in the pronotum, while females had wider abdominal sternites. Although there were significant differences in shape and size between mature forests and second-growth forest, these were less significant among the sites within each type of vegetal formation. Individuals had more shape variations in the mature forest. We suggest that differences in shape are due at least in part to the isolation of the habitat. The differences found between sexes raises the question of how morphological variations and sexual dimorphism may be affected spatially by natural selection. PMID:21870986

  17. Facilitation within species: a possible origin of group-selected superorganisms.

    PubMed

    McIntire, Eliot J B; Fajardo, Alex

    2011-07-01

    Facilitation (positive interactions) has emerged as a dominant ecological mechanism in many ecosystems. Its importance has recently been expanded to include intraspecific interactions, creating the potential for higher-level natural selection within species. Using multiple lines of evidence, we show that conspecific facilitation within the southern beech tree, Nothofagus pumilio, appears to overcome competition in two life phases. In a seedling experiment addressing stress and planting-density effects, we found that mortality was lowest (∼0%) where there was no stress and was indistinguishable across densities. Furthermore, in mature forests (45 years old), genetically variable, merged individuals had lower mortality (-50%) than unmerged individuals in locations without identifiable stress. Thus, a full understanding of the occurrence of facilitation may require a more general model of resource improvements than the commonly cited stress gradient hypothesis. Additionally, the merged trees showed a density-dependent mortality pattern at the level of the group. These data demonstrate a potential mechanism (facilitation) driving natural selection at this higher level, via stem merging. These merged "superorganisms" would confirm theoretical predictions whereby facilitation acts as an ecological mechanism driving group selection.

  18. Extreme environments in the forests of Ushuaia, Argentina

    NASA Astrophysics Data System (ADS)

    D'Antoni, Hector; Rothschild, Lynn; Schultz, Cynthia; Burgess, Seth; Skiles, J. W.

    2007-11-01

    A survey over two mountain slopes (Glaciar Martial and Cerro Guanaco) in the vicinity of Ushuaia (Tierra del Fuego, Argentina) showed normal results for the region in terms of chlorophyll concentration in the leaves of the dominant tree species Nothofagus antarctica, N. pumilio and N. betuloides, and soil variables such as temperature, moisture, pH, and concentration of nitrogen, sodium and potassium. Solar radiation, on the other hand, showed high values of ultraviolet over the 200-400 nm range, suggesting that the environment is extreme in terms of incoming solar radiation. The forest canopy absorbs and/or reflects a significant amount of that radiation. In separate analyses we showed that these tree species contain UV-absorbing pigments (cyanidin, delphidin, and flavonol glycosides). We submit that the rippled and glossy surface of leaves serves as a reflection/backscattering mechanism that protects their inner structure and function. The presence of krummholz (= twisted, dwarf trees) in the upper end of the forest shows the effects of an extreme environment.

  19. Remote Sensing in Archeology: Classifying Bajos of the Paten, Guatemala

    NASA Technical Reports Server (NTRS)

    Lowry, James D., Jr.

    1998-01-01

    This project focuses on the adaptation of human populations to their environments from prehistoric times to the present. It emphasizes interdisciplinary research to develop ecological baselines through the use of remotely sensed imagery, in situ field work, and the modeling of human population dynamics. It utilizes cultural and biological data from dated archaeological sites to assess the subsistence and settlement patterns of human societies in response to changing climatic and environmental conditions. The utilization of remote sensing techniques in archaeology is relatively new, exciting, and opens many doors.

  20. In the right place at the right time: habitat representation in protected areas of South American Nothofagus-dominated plants after a dispersal constrained climate change scenario.

    PubMed

    Alarcón, Diego; Cavieres, Lohengrin A

    2015-01-01

    In order to assess the effects of climate change in temperate rainforest plants in southern South America in terms of habitat size, representation in protected areas, considering also if the expected impacts are similar for dominant trees and understory plant species, we used niche modeling constrained by species migration on 118 plant species, considering two groups of dominant trees and two groups of understory ferns. Representation in protected areas included Chilean national protected areas, private protected areas, and priority areas planned for future reserves, with two thresholds for minimum representation at the country level: 10% and 17%. With a 10% representation threshold, national protected areas currently represent only 50% of the assessed species. Private reserves are important since they increase up to 66% the species representation level. Besides, 97% of the evaluated species may achieve the minimum representation target only if the proposed priority areas were included. With the climate change scenario representation levels slightly increase to 53%, 69%, and 99%, respectively, to the categories previously mentioned. Thus, the current location of all the representation categories is useful for overcoming climate change by 2050. Climate change impacts on habitat size and representation of dominant trees in protected areas are not applicable to understory plants, highlighting the importance of assessing these effects with a larger number of species. Although climate change will modify the habitat size of plant species in South American temperate rainforests, it will have no significant impact in terms of the number of species adequately represented in Chile, where the implementation of the proposed reserves is vital to accomplish the present and future minimum representation. Our results also show the importance of using migration dispersal constraints to develop more realistic future habitat maps from climate change predictions.

  1. In the Right Place at the Right Time: Habitat Representation in Protected Areas of South American Nothofagus-Dominated Plants after a Dispersal Constrained Climate Change Scenario

    PubMed Central

    Alarcón, Diego; Cavieres, Lohengrin A.

    2015-01-01

    In order to assess the effects of climate change in temperate rainforest plants in southern South America in terms of habitat size, representation in protected areas, considering also if the expected impacts are similar for dominant trees and understory plant species, we used niche modeling constrained by species migration on 118 plant species, considering two groups of dominant trees and two groups of understory ferns. Representation in protected areas included Chilean national protected areas, private protected areas, and priority areas planned for future reserves, with two thresholds for minimum representation at the country level: 10% and 17%. With a 10% representation threshold, national protected areas currently represent only 50% of the assessed species. Private reserves are important since they increase up to 66% the species representation level. Besides, 97% of the evaluated species may achieve the minimum representation target only if the proposed priority areas were included. With the climate change scenario representation levels slightly increase to 53%, 69%, and 99%, respectively, to the categories previously mentioned. Thus, the current location of all the representation categories is useful for overcoming climate change by 2050. Climate change impacts on habitat size and representation of dominant trees in protected areas are not applicable to understory plants, highlighting the importance of assessing these effects with a larger number of species. Although climate change will modify the habitat size of plant species in South American temperate rainforests, it will have no significant impact in terms of the number of species adequately represented in Chile, where the implementation of the proposed reserves is vital to accomplish the present and future minimum representation. Our results also show the importance of using migration dispersal constraints to develop more realistic future habitat maps from climate change predictions. PMID:25786226

  2. Disturbance and density-dependent processes (competition and facilitation) influence the fine-scale genetic structure of a tree species’ population

    PubMed Central

    Fajardo, Alex; Torres-Díaz, Cristian; Till-Bottraud, Irène

    2016-01-01

    Background and Aims Disturbances, dispersal and biotic interactions are three major drivers of the spatial distribution of genotypes within populations, the last of which has been less studied than the other two. This study aimed to determine the role of competition and facilitation in the degree of conspecific genetic relatedness of nearby individuals of tree populations. It was expected that competition among conspecifics will lead to low relatedness, while facilitation will lead to high relatedness (selection for high relatedness within clusters). Methods The stand structure and spatial genetic structure (SGS) of trees were examined within old-growth and second-growth forests (including multi-stemmed trees at the edge of forests) of Nothofagus pumilio following large-scale fires in Patagonia, Chile. Genetic spatial autocorrelations were computed on a spatially explicit sampling of the forests using five microsatellite loci. As biotic plant interactions occur among immediate neighbours, mean nearest neighbour distance (MNND) among trees was computed as a threshold for distinguishing the effects of disturbances and biotic interactions. Key Results All forests exhibited a significant SGS for distances greater than the MNND. The old-growth forest genetic and stand structure indicated gap recolonization from nearby trees (significantly related trees at distances between 4 and 10 m). At distances smaller than the MNND, trees of the second-growth interior forest showed significantly lower relatedness, suggesting a fading of the recolonization structure by competition, whereas the second-growth edge forest showed a positive and highly significant relatedness among trees (higher among stems of a cluster than among stems of different clusters), resulting from facilitation. Conclusions Biotic interactions are shown to influence the genetic composition of a tree population. However, facilitation can only persist if individuals are related. Thus, the genetic composition in

  3. Extreme defoliation reduces tree growth but not C and N storage in a winter-deciduous species

    PubMed Central

    Piper, Frida I.; Gundale, Michael J.; Fajardo, Alex

    2015-01-01

    Background and Aims There is a growing concern about how forests will respond to increased herbivory associated with climate change. Carbon (C) and nitrogen (N) limitation are hypothesized to cause decreasing growth after defoliation, and eventually mortality. This study examines the effects of a natural and massive defoliation by an insect on mature trees’ C and N storage, which have rarely been studied together, particularly in winter-deciduous species. Methods Survival, growth rate, carbon [C, as non-structural carbohydrate (NSC) concentration] and nitrogen (N) storage, defences (tannins and total polyphenols), and re-foliation traits were examined in naturally defoliated and non-defoliated adult trees of the winter-deciduous temperate species Nothofagus pumilio 1 and 2 years after a massive and complete defoliation caused by the caterpillar of Ormiscodes amphimone (Saturniidae) during summer 2009 in Patagonia. Key Results Defoliated trees did not die but grew significantly less than non-defoliated trees for at least 2 years after defoliation. One year after defoliation, defoliated trees had similar NSC and N concentrations in woody tissues, higher polyphenol concentrations and lower re-foliation than non-defoliated trees. In the second year, however, NSC concentrations in branches were significantly higher in defoliated trees while differences in polyphenols and re-foliation disappeared and decreased, respectively. Conclusions The significant reduction in growth following defoliation was not caused by insufficient C or N availability, as frequently assumed; instead, it was probably due to growth limitations due to factors other than C or N, or to preventative C allocation to storage. This study shows an integrative approach to evaluating plant growth limitations in response to disturbance, by examining major resources other than C (e.g. N), and other C sinks besides storage and growth (e.g. defences and re-foliation). PMID:25851136

  4. Validating numerical simulations of snow avalanches using dendrochronology: the Cerro Ventana event in Northern Patagonia, Argentina

    NASA Astrophysics Data System (ADS)

    Casteller, A.; Christen, M.; Villalba, R.; Martínez, H.; Stöckli, V.; Leiva, J. C.; Bartelt, P.

    2008-05-01

    The damage caused by snow avalanches to property and human lives is underestimated in many regions around the world, especially where this natural hazard remains poorly documented. One such region is the Argentinean Andes, where numerous settlements are threatened almost every winter by large snow avalanches. On 1 September 2002, the largest tragedy in the history of Argentinean mountaineering took place at Cerro Ventana, Northern Patagonia: nine persons were killed and seven others injured by a snow avalanche. In this paper, we combine both numerical modeling and dendrochronological investigations to reconstruct this event. Using information released by local governmental authorities and compiled in the field, the avalanche event was numerically simulated using the avalanche dynamics programs AVAL-1D and RAMMS. Avalanche characteristics, such as extent and date were determined using dendrochronological techniques. Model simulation results were compared with documentary and tree-ring evidences for the 2002 event. Our results show a good agreement between the simulated projection of the avalanche and its reconstructed extent using tree-ring records. Differences between the observed and the simulated avalanche, principally related to the snow height deposition in the run-out zone, are mostly attributed to the low resolution of the digital elevation model used to represent the valley topography. The main contributions of this study are (1) to provide the first calibration of numerical avalanche models for the Patagonian Andes and (2) to highlight the potential of textit{Nothofagus pumilio} tree-ring records to reconstruct past snow-avalanche events in time and space. Future research should focus on testing this combined approach in other forested regions of the Andes.

  5. Extreme defoliation reduces tree growth but not C and N storage in a winter-deciduous species.

    PubMed

    Piper, Frida I; Gundale, Michael J; Fajardo, Alex

    2015-06-01

    There is a growing concern about how forests will respond to increased herbivory associated with climate change. Carbon (C) and nitrogen (N) limitation are hypothesized to cause decreasing growth after defoliation, and eventually mortality. This study examines the effects of a natural and massive defoliation by an insect on mature trees' C and N storage, which have rarely been studied together, particularly in winter-deciduous species. Survival, growth rate, carbon [C, as non-structural carbohydrate (NSC) concentration] and nitrogen (N) storage, defences (tannins and total polyphenols), and re-foliation traits were examined in naturally defoliated and non-defoliated adult trees of the winter-deciduous temperate species Nothofagus pumilio 1 and 2 years after a massive and complete defoliation caused by the caterpillar of Ormiscodes amphimone (Saturniidae) during summer 2009 in Patagonia. Defoliated trees did not die but grew significantly less than non-defoliated trees for at least 2 years after defoliation. One year after defoliation, defoliated trees had similar NSC and N concentrations in woody tissues, higher polyphenol concentrations and lower re-foliation than non-defoliated trees. In the second year, however, NSC concentrations in branches were significantly higher in defoliated trees while differences in polyphenols and re-foliation disappeared and decreased, respectively. The significant reduction in growth following defoliation was not caused by insufficient C or N availability, as frequently assumed; instead, it was probably due to growth limitations due to factors other than C or N, or to preventative C allocation to storage. This study shows an integrative approach to evaluating plant growth limitations in response to disturbance, by examining major resources other than C (e.g. N), and other C sinks besides storage and growth (e.g. defences and re-foliation). © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany

  6. Plant Responses to Increased UV-B Radiation: A Research Project

    NASA Technical Reports Server (NTRS)

    DAntoni, H. L.; Skiles, J. W.; Armstrong, R.; Coughlan, J.; Daleo, G.; Mayoral, A.; Lawless, James G. (Technical Monitor)

    1994-01-01

    because there is anecdotal evidence of plant damage on the saguaros that has been linked to increased UV radiation, and (3) the forests of Nothofagus spp. and the steppe of Patagonia where the risk of plant damage at 35S is 5% and increases to as much as 15% at 55S due to increased UV-B radiation. Measurements of UV-B radiation impinging on the surface at 55S largely exceed the predicted UV-B radiation values at 50 latitude and 0% ozone depletion. Preliminary HPLC analyses of UV-B absorbing compounds in Nothofagus antartica, N. pumilio, N. betuloides and Rumex sp. in natural conditions show species-specific patterns. The spectrum of N. antartica grown at 38S differs significantly from that of N. antartica in natural conditions in Ushuaia (55S). These results suggest that the selected main area (Patagonia) is appropriate for assessing the problem and its magnitude and that Nothofagus is appropriate for our study.

  7. Plant Responses to Increased UV-B Radiation: A Research Project

    NASA Technical Reports Server (NTRS)

    DAntoni, H. L.; Skiles, J. W.; Armstrong, R.; Coughlan, J.; Daleo, G.; Mayoral, A.; Lawless, James G. (Technical Monitor)

    1994-01-01

    because there is anecdotal evidence of plant damage on the saguaros that has been linked to increased UV radiation, and (3) the forests of Nothofagus spp. and the steppe of Patagonia where the risk of plant damage at 35S is 5% and increases to as much as 15% at 55S due to increased UV-B radiation. Measurements of UV-B radiation impinging on the surface at 55S largely exceed the predicted UV-B radiation values at 50 latitude and 0% ozone depletion. Preliminary HPLC analyses of UV-B absorbing compounds in Nothofagus antartica, N. pumilio, N. betuloides and Rumex sp. in natural conditions show species-specific patterns. The spectrum of N. antartica grown at 38S differs significantly from that of N. antartica in natural conditions in Ushuaia (55S). These results suggest that the selected main area (Patagonia) is appropriate for assessing the problem and its magnitude and that Nothofagus is appropriate for our study.

  8. Disturbance and density-dependent processes (competition and facilitation) influence the fine-scale genetic structure of a tree species' population.

    PubMed

    Fajardo, Alex; Torres-Díaz, Cristian; Till-Bottraud, Irène

    2016-01-01

    Disturbances, dispersal and biotic interactions are three major drivers of the spatial distribution of genotypes within populations, the last of which has been less studied than the other two. This study aimed to determine the role of competition and facilitation in the degree of conspecific genetic relatedness of nearby individuals of tree populations. It was expected that competition among conspecifics will lead to low relatedness, while facilitation will lead to high relatedness (selection for high relatedness within clusters). The stand structure and spatial genetic structure (SGS) of trees were examined within old-growth and second-growth forests (including multi-stemmed trees at the edge of forests) of Nothofagus pumilio following large-scale fires in Patagonia, Chile. Genetic spatial autocorrelations were computed on a spatially explicit sampling of the forests using five microsatellite loci. As biotic plant interactions occur among immediate neighbours, mean nearest neighbour distance (MNND) among trees was computed as a threshold for distinguishing the effects of disturbances and biotic interactions. All forests exhibited a significant SGS for distances greater than the MNND. The old-growth forest genetic and stand structure indicated gap recolonization from nearby trees (significantly related trees at distances between 4 and 10 m). At distances smaller than the MNND, trees of the second-growth interior forest showed significantly lower relatedness, suggesting a fading of the recolonization structure by competition, whereas the second-growth edge forest showed a positive and highly significant relatedness among trees (higher among stems of a cluster than among stems of different clusters), resulting from facilitation. Biotic interactions are shown to influence the genetic composition of a tree population. However, facilitation can only persist if individuals are related. Thus, the genetic composition in turn influences what type of biotic interactions

  9. Textos y gramatica del Pima Bajo (Texts and Grammar of the Lower Pima).

    ERIC Educational Resources Information Center

    Escalante, Roberto H.; Fernandez, Zarina Estrada

    This volume, entirely in Spanish and Pima, presents extensive descriptive information about the language spoken by the Pima of Mexico. An introductory chapter reviews the history of research on the language. The second and third chapters explain its phonology and morphology. In the fourth chapter, a number of oral histories and ethnographic texts…

  10. Ectomycorrhizal fungal communities coinvading with Pinaceae host plants in Argentina: Gringos bajo el bosque.

    PubMed

    Hayward, Jeremy; Horton, Thomas R; Nuñez, Martin A

    2015-10-01

    Coinvasive ectomycorrhizal (ECM) fungi allow Pinaceae species to invade regions otherwise lacking compatible symbionts, but ECM fungal communities permitting Pinaceae invasions are poorly understood. In the context of Pinaceae invasions on Isla Victoria, Nahuel Huapi National Park, Argentina, we asked: what ECM fungi are coinvading with Pinaceae hosts on Isla Victoria; are some ECM fungal species or genera more prone to invade than others; and are all ECM fungal species that associate with Northern Hemisphere hosts also nonnative, or are some native fungi compatible with nonnative plants? We sampled ECMs from 226 Pinaceae host plant individuals, both planted individuals and recruits, growing inside and invading from plantations. We used molecular techniques to examine ECM fungal communities associating with these trees. A distinctive subset of the ECM fungal community predominated far from plantations, indicating differences between highly invasive and less invasive ECM fungi. Some fungal invaders reported here have been detected in other locations around the world, suggesting strong invasion potential. Fungi that were frequently detected far from plantations are often found in early-successional sites in the native range, while fungi identified as late-successional species in the native range are rarely found far from plantations, suggesting a means for predicting potential fungal coinvaders.

  11. Liquefaction and fluidization structures in Messinian storm deposits (Bajo Segura Basin, Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Alfaro, P.; Delgado, J.; Estévez, A.; Molina, J. M.; Moretti, M.; Soria, J. M.

    2002-05-01

    Synsedimentary deformation structures are recognized in Upper Miocene deposits of the eastern Betic Cordillera (SE Spain). A singular stratigraphic section in these deposits shows several levels with soft-sediment deformation structures (load casts, ball-and-pillows and pipes) induced by liquidization (liquefaction and/or fluidization) of sandy sediments. The morphologic analysis of these structures reveals a liquidized sediment thickness ranging from 0.1 to 1.5 m. Although they have been previously interpreted as a result of seismic shocks, their origin was most likely related to the action of storm waves as the structures are always associated with tempestites. Facies analysis, geometrical features of the deformed beds and appraisal of geotechnical properties for shelf and coastal sediments allow the soft-sediment deformation structures to be interpreted as a result of the cyclic effect of storm waves on unconsolidated sediments, and excludes other processes such as overloading, tsunamis or the impact of breaking waves.

  12. Textos y gramatica del Pima Bajo (Texts and Grammar of the Lower Pima).

    ERIC Educational Resources Information Center

    Escalante, Roberto H.; Fernandez, Zarina Estrada

    This volume, entirely in Spanish and Pima, presents extensive descriptive information about the language spoken by the Pima of Mexico. An introductory chapter reviews the history of research on the language. The second and third chapters explain its phonology and morphology. In the fourth chapter, a number of oral histories and ethnographic texts…

  13. Invarianza de las ecuaciones de movimiento bajo transformaciones de escala espacio-temporales en la dinamica de Newton modificada (MOND)

    NASA Astrophysics Data System (ADS)

    Acosta, R.; Tuiran, E.; Molina Redondo, U.

    2015-02-01

    The basic principles that originated the Modified Newtonian Dynamics MOND, are shown, as well as a description of the fundamentals aspects of the theory: modification of gravity and modification of inertia. Also, it is considered the behaviour of the movement equations under space-temporal scale transformations of the movement equations, that is, transformations that have the form (t, r) --> (lambda*t, r). It was observed in this way that the MOND regime comes from the requirement of the invariance of the movement equations with respect to this transformations.

  14. Migrant Education Programs Under ESEA Title I Migrant Amendment. (Programas de Educacion Migrante bajo el Titulo I de ESEA.)

    ERIC Educational Resources Information Center

    Minkler, Elton D.

    Migrant Education Programs are designed for those students who, because of the migratory nature of their parents' employment, are required to move from one school district to another during the school year. In many instances these students, because of sporadic attendance and discontinuity of their educational experiences, have found it difficult,…

  15. Reconstructing streamflow variation of the Baker River from tree-rings in Northern Patagonia since 1765

    NASA Astrophysics Data System (ADS)

    Lara, Antonio; Bahamondez, Alejandra; González-Reyes, Alvaro; Muñoz, Ariel A.; Cuq, Emilio; Ruiz-Gómez, Carolina

    2015-10-01

    The understanding of the long-term variation of large rivers streamflow with a high economic and social relevance is necessary in order to improve the planning and management of water resources in different regions of the world. The Baker River has the highest mean discharge of those draining both slopes of the Andes South of 20°S and it is among the six rivers with the highest mean streamflow in the Pacific domain of South America (1100 m3 s-1 at its outlet). It drains an international basin of 29,000 km2 shared by Chile and Argentina and has a high ecologic and economic value including conservation, tourism, recreational fishing, and projected hydropower. This study reconstructs the austral summer - early fall (January-April) streamflow for the Baker River from Nothofagus pumilio tree-rings for the period 1765-2004. Summer streamflow represents 45.2% of the annual discharge. The regression model for the period (1961-2004) explains 54% of the variance of the Baker River streamflow (R2adj = 0.54). The most significant temporal pattern in the record is the sustained decline since the 1980s (τ = -0.633, p = 1.0144 ∗ 10-5 for the 1985-2004 period), which is unprecedented since 1765. The Correlation of the Baker streamflow with the November-April observed Southern Annular Mode (SAM) is significant (1961-2004, r = -0.55, p < 0.001). The Baker record is also correlated with the available SAM tree-ring reconstruction based on other species when both series are filtered with a 25-year spline and detrended (1765-2004, r = -0.41, p < 0.01), emphasizing SAM as the main climatic forcing of the Baker streamflow. Three of the five summers with the highest streamflow in the entire reconstructed record occurred after the 1950s (1977, 1958 and 1959). The causes of this high streamflow events are not yet clear and cannot be associated with the reported recent increase in the frequency of glacial-lake outburst floods (GLOFs). The decreasing trend in the observed and reconstructed

  16. Helminth parasitism in two closely related South African rodents: abundance, prevalence, species richness and impinging factors.

    PubMed

    Spickett, Andrea; Junker, Kerstin; Krasnov, Boris R; Haukisalmi, Voitto; Matthee, Sonja

    2017-04-01

    We investigated patterns of helminth infection in two closely related rodents (social Rhabdomys pumilio occurring mainly in xeric habitats and solitary R. dilectus occurring mainly in mesic habitats) at 20 localities in different biomes of South Africa and asked if between-species differences were mainly caused by difference in sociality or difference in environmental conditions of their respective habitats. Helminths recovered from the gastrointestinal tract totalled 11 nematode and 5 cestode species from R. pumilio and 19 nematode and 7 cestode species from R. dilectus. In both hosts, mean abundance and prevalence of nematodes were higher compared to cestodes. Cestode infection as well as nematode abundance, species richness or prevalence did not differ between the two rodents. However, incidence of nematode infection was significantly higher in R. dilectus than in R. pumilio. Moreover, nematode numbers and species richness in infracommunities of R. pumilio inhabiting the relatively more xeric Karoo biome were significantly lower than in those inhabiting the relatively less xeric Fynbos biome. Although we could not unequivocally distinguish between effects of host sociality and environmental factors on the number of individuals and species of helminths in the two hosts, differences in the incidence of nematode infection between R. pumilio and R. dilectus as well as differences in the number of nematode individuals and species between R. pumilio from the Fynbos and the Karoo suggested the effect of environmental conditions on helminth infection to be more important than that of sociality.

  17. Sequestrate fungi of New Zealand: Elaphomyces (Ascomycota, Eurotiales, Elaphomycetaceae)

    Treesearch

    Michael A. Castellano; Ross E. Beever; James M. Trappe

    2012-01-01

    Four species of the sequestrate fungal genus Elaphomyces are reported from New Zealand: Elaphomyces bollardii sp. nov. associated with Leptospermum spp. and Kunzea ericoides, E. luteicrustus sp. nov. associated with Nothofagus menziesii, E. putridus sp. nov. associated with...

  18. Preguntas Y Respuestas, Programa para Ninos Migratorios Bajo el Titulo I de ESEA. 1971. (Questions and Answers, Program for Migrant Children Under ESEA Title I. 1971).

    ERIC Educational Resources Information Center

    Office of Education (DHEW), Washington, DC. Office of Programs for the Disadvantaged.

    Title I of the Elementary and Secondary Education Act of 1965 is specifically designed to help educationally deprived children. It was amended in 1966 to include the children of migratory agricultural workers. Today more than 235,000 migrant children receive educational and special supplementary services under Title I. Answers to some of the…

  19. Sistemas de Documentacion e Informacion Educativa en Belgica, Paises Bajos y Francia (Educational Documentation and Information Systems in Belgium, Holland, and France).

    ERIC Educational Resources Information Center

    Rossi Etchelouz, Nelly Yvis

    This booklet describes the working and organization of the information and documentation systems in Belgium, the Netherlands, and France. The discussion begins with a look at the Belgium educational system and how information services operate within that system. The central library, specialized services, and specialized information centers are all…

  20. Parent Councils for Migrant Education Under ESEA Title I Migrant Amendment. (Concilios de Padres para Educacion Migratoria bajo el Titulo I de ESEA.)

    ERIC Educational Resources Information Center

    Minkler, Elton D.

    An educational program's quality and relevance can be guaranteed only if the needs of the students it serves are accommodated. To be certain that the program meets these needs, parents and students must be involved in its planning and implementation. One vehicle to achieve this goal is the parent advisory council. Prepared for the parents and…

  1. Identity of Two Sympatric Species of Orius (Hemiptera: Heteroptera: Anthocoridae)

    PubMed Central

    Shapiro, Jeffrey P.; Shirk, Paul D.; Kelley, Karen; Lewis, Tamera M.; Horton, David R.

    2010-01-01

    The minute pirate bugs, Orius insidiosus (Say) and Orius pumilio (Champion) (Hemiptera: Heteroptera: Anthocoridae), are closely related species known to be sympatric in north Florida. Here, male and female genitalia, DNA sequences, and the effects of within- and between-species pairings on egg production and egg development were examined to develop a better understanding of the relationship between these two species. Interspecific matings between the two species did not result in viable progeny. Although there were gross similarities in the morphology of the male parameres (external genitalia) between the two species, the cone in O. pumilio was much broader with a greater spiral twist and the flagellum was longer than in O. insidiosus. Correspondingly, there were differences in the morphology of the copulatory tubes of the females of the two species. In O. insidiosus, the organ was somewhat longer than in O. pumilio and oriented parallel to the abdominal midline, while the copulatory tube in O. pumilio tilted slightly towards the midline. Additionally, the copulatory tube for O. pumilio included a sclerotized basal mound that was not present in O. insidiosus. These morphological differences suggest that successful copulation between these species could be difficult. In contrast to conspecific matings, interspecific matings resulted in few or no eggs laid over a period of two weeks and no viable progeny. Comparison of the 18S ribosomal gene ITS-1 sequences between the two species demonstrated only 91% homology. When yolk protein contents were examined to determine whether reproductive physiology had shifted to full egg production, interspecifically mated females contained amounts of yolk protein comparable to that in fed, but unmated females; this was less than 10% of the yolk protein previously found in fed and conspecifically mated females. These findings together confirm that O. insidiosus and O. pumilio are indeed two separate species. PMID:21265614

  2. Efficacy of four traps in capturing male Helicoverpa moths in north Florida

    USDA-ARS?s Scientific Manuscript database

    Two closely related species of Orius (Hemiptera:Anthocoridae) inhabit the Florida peninsula. While O. insidiosus is nearly ubiquitous east of the Rocky Mountains, O. pumilio is a tropical/subtropical species found in the U.S. no farther north than Alachua County. For two seasons we have observed p...

  3. Finding the missing code of RNA recognition by PUF proteins

    PubMed Central

    Chen, Yu; Varani, Gabriele

    2011-01-01

    Pumilio and FBF homology (PUF) proteins represent highly promising candidates for engineering sequence-specific RNA recognition, but were only known to recognize G, A and U, significantly limiting applications. Two groups (Filipovska et al., 2011; Dong et al., 2011) have now reported the discovery of the cytosine-recognition code for PUF proteins. PMID:21802002

  4. Optimality and nitrogen allocation in a tree canopy

    Treesearch

    D.Y. Hollinger

    1996-01-01

    Physical and functional properties of foliage were measured at a variety of microsites in a broad-leaved Nothofagus fusca (Hook. f.) Orst. canopy. The light climate of the foliage at these sites was monitored for 39 days in the late sprlng and early summer with in situ sensors. Foliage nitrogen content (N), mean leaf angle, and gas exchange...

  5. Piracy in the high trees: ectomycorrhizal fungi from an aerial 'canopy soil' microhabitat.

    PubMed

    Orlovich, David A; Draffin, Suzy J; Daly, Robert A; Stephenson, Steven L

    2013-01-01

    The mantle of dead organic material ("canopy soil") associated with the mats of vascular and nonvascular epiphytes found on the branches of trees in the temperate rainforests along the southwestern coast of the South Island of New Zealand were examined for evidence of ectomycorrhizal fungi. DNA sequencing and cluster analysis were used to identify the taxa of fungi present in 74 root tips collected from the canopy soil microhabitat of three old growth Nothofagus menziesii trees in the South West New Zealand World Heritage Area. A diverse assemblage of ectomycorrhizal fungi was found to infect an extensive network of adventitious canopy roots of Nothofagus menziesii in this forest, including 14 phylotypes from nine genera of putative ectomycorrhizal fungi. Seven of the genera identified previously were known to form ectomycorrhizas with terrestrial roots of Nothofagus: Cortinarius, Russula, Cenococcum, Thelephora/Tomentella, Lactarius and Laccaria; two, Clavulina and Leotia, previously have not been reported forming ectomycorrhizas with Nothofagus. Canopy ectomycorrhizas provide an unexpected means for increased host nutrition that may have functional significance in some forest ecosystems. Presumably, canopy ectomycorrhizas on host adventitious roots circumvent the tree-ground-soil nutrient cycle by accessing a wider range of nutrients directly in the canopy than would be possible for non-mycorrhizal or arbuscular mycorrhizal canopy roots. In this system, both host and epiphytes would seem to be in competition for the same pool of nutrients in canopy soil.

  6. Postglacial vegetation, climate, and fire history along the east side of the Andes (lat 41-42.5°S), Argentina

    NASA Astrophysics Data System (ADS)

    Whitlock, Cathy; Bianchi, Maria Martha; Bartlein, Patrick J.; Markgraf, Vera; Marlon, Jennifer; Walsh, Megan; McCoy, Neil

    2006-09-01

    The history of the low-elevation forest and forest-steppe ecotone on the east side of the Andes is revealed in pollen and charcoal records obtained from mid-latitude lakes. Prior to 15,000 cal yr BP, the vegetation was characterized by steppe vegetation with isolated stands of Nothofagus. The climate was generally dry, and the sparse vegetation apparently lacked sufficient fuels to burn extensively. After 15,000 cal yr BP, a mixture of Nothofagus forest and shrubland/steppe developed. Fire activity increased between 13,250 and 11,400 cal yr BP, contemporaneous with a regionally defined cold dry period (Huelmo/Mascardi Cold Reversal). The early-Holocene period was characterized by an open Nothofagus forest/shrubland mosaic, and fire frequency was high in dry sites and low in wet sites; the data suggest a sharp decrease in moisture eastward from the Andes. A shift to a surface-fire regime occurred at 7500 cal yr BP at the wet site and at 4400 cal yr BP at the dry site, preceding the expansion of Austrocedrus by 1000-1500 yr. The spread of Austrocedrus is explained by a shift towards a cooler and wetter climate in the middle and late Holocene. The change to a surface-fire regime is consistent with increased interannual climate variability and the onset or strengthening of ENSO. The present-day mixed forest dominated by Nothofagus and Austrocedrus was established in the last few millennia.

  7. Late-Holocene rodent middens from Rio Limay, Neuquen Province, Argentina

    USGS Publications Warehouse

    Markgraf, Vera; Betancourt, J.; Rylander, K.A.

    1997-01-01

    Pollen analysis of late-Holocene amberat deposits from two caves near the forest-steppe ecotone in northern Patagonia documents a major shift from Austrocedrus-Nothofagus forest to steppe shrub assemblages some time after 1800 and before 1300 BP. The probable explanation of the reduction of tree taxa calls for either drier summers or intensified land use or a combination of both.

  8. Habitat association patterns of forest and steppe birds of northern Patagonia, Argentina

    Treesearch

    C. John Ralph

    1985-01-01

    I censused birds across a moisture gradient in northern Patagonia, Argentina, in the vicinity of Bariloche. Over a 60-km distance, the 12 sites ranged from grassland at lower elevations to upland climax Nothofagus forests of the eastern Andes. Here, I correlated bird abundance and diversities with various vegetation measures. Using all sites, bird...

  9. Collaborative Project Work Development in a Virtual Environment with Low-Intermediate Undergraduate Colombian Students (Desarrollo de trabajo colaborativo en un ambiente virtual con estudiantes colombianos de pregrado de nivel intermedio-bajo)

    ERIC Educational Resources Information Center

    Salinas Vacca, Yakelin

    2014-01-01

    This paper reports on an exploratory, descriptive, and interpretive study in which the roles of discussion boards, the students, the teacher, and the monitors were explored as they constructed a collaborative class project in a virtual environment. This research was conducted in the virtual program of a Colombian public university. Data were…

  10. Los Derechos de las Personas Incapacitadas Bajo la Ley Federal. Seccion 504 de la Ley de Rehabilitacion de 1973 (Handicapped Persons's Rights under Federal Law. Section 504 of the Rehabilitation Act of 1973).

    ERIC Educational Resources Information Center

    Office for Civil Rights (ED), Washington, DC.

    This Spanish-language pamphlet explains Section 504 of the Rehabilitation Act of 1973, which outlaws disability discrimination in programs receiving federal funds and the extensive regulations stemming from Section 504. The rights and responsibilities of handicapped persons are related to the following issues: eligibility for coverage under the…

  11. Visual mate choice in poison frogs.

    PubMed

    Summers, K; Symula, R; Clough, M; Cronin, T

    1999-11-07

    We investigated female mate choice on the basis of visual cues in two populations of Dendrobates pumilio, the strawberry poison frog, from the Bocas del Toro Archipelago in Panama, Central America. Mate choice experiments were carried out by presenting subject females of each of two morphs of this species (orange and green) from two different island populations (Nancy Key and Pope Island) with object frogs (one of each morph) under glass at one end of a terrarium. Recorded calls were played simultaneously from behind both object frogs. The experiments were carried out under two light regimes: (i) white light, and (ii) relatively monochromatic filtered blue light. Subject females from each population displayed a significant preference for their own morph under white light, but not under blue light. These results indicate that female D. pumilio use visual cues in mate choice, and suggest that colour may be the visual cue they use.

  12. Nop9 binds the central pseudoknot region of 18S rRNA

    PubMed Central

    Wang, Bing

    2017-01-01

    Abstract The assembly of eukaryotic ribosomes requires numerous factors that transiently associate with evolving pre-ribosomal particles. The Pumilio repeat-containing protein Nop9 briefly associates with the 90S pre-ribosome during its co-transcriptional assembly. Here, we show that Nop9 specifically binds an 11-nucleotide sequence of 18S rRNA that forms the 3΄ side of the central pseudoknot and helix 28 in the mature subunit. Crystal structures of Nop9 in the free and RNA-bound states reveal a new type of Pumilio repeat protein with a distinct structure, target sequence and RNA-binding mode. Nop9 contains 10 Pumilio repeats arranged into a U-shaped scaffold. The target RNA is recognized by two stretches of repeats in a bipartite manner, and three central bases are unrecognized as a result of the degeneracy of repeats 6 and 7. Our data suggest that Nop9 regulates the folding of 18S rRNA at early assembly stages of 90S. PMID:28053123

  13. Nop9 binds the central pseudoknot region of 18S rRNA.

    PubMed

    Wang, Bing; Ye, Keqiong

    2017-04-07

    The assembly of eukaryotic ribosomes requires numerous factors that transiently associate with evolving pre-ribosomal particles. The Pumilio repeat-containing protein Nop9 briefly associates with the 90S pre-ribosome during its co-transcriptional assembly. Here, we show that Nop9 specifically binds an 11-nucleotide sequence of 18S rRNA that forms the 3΄ side of the central pseudoknot and helix 28 in the mature subunit. Crystal structures of Nop9 in the free and RNA-bound states reveal a new type of Pumilio repeat protein with a distinct structure, target sequence and RNA-binding mode. Nop9 contains 10 Pumilio repeats arranged into a U-shaped scaffold. The target RNA is recognized by two stretches of repeats in a bipartite manner, and three central bases are unrecognized as a result of the degeneracy of repeats 6 and 7. Our data suggest that Nop9 regulates the folding of 18S rRNA at early assembly stages of 90S. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  14. Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog

    PubMed Central

    Maan, Martine E.; Cummings, Molly E.

    2009-01-01

    It is commonly assumed that natural selection imposed by predators is the prevailing force driving the evolution of aposematic traits. Here, we demonstrate that aposematic signals are shaped by sexual selection as well. We evaluated sexual selection for coloration brightness in populations of the poison frog Oophaga [Dendrobates] pumilio in Panama's Bocas del Toro archipelago. We assessed female preferences for brighter males by manipulating the perceived brightness of spectrally matched males in two-way choice experiments. We found strong female preferences for bright males in two island populations and weaker or ambiguous preferences in females from mainland populations. Spectral reflectance measurements, coupled with an O. pumilio-specific visual processing model, showed that O. pumilio coloration was significantly brighter in island than in mainland morphs. In one of the island populations (Isla Solarte), males were significantly more brightly colored than females. Taken together, these results provide evidence for directional sexual selection on aposematic coloration and document sexual dimorphism in vertebrate warning coloration. Although aposematic signals have long been upheld as exemplars of natural selection, our results show that sexual selection should not be ignored in studies of aposematic evolution. PMID:19858491

  15. Community structure of helminth parasites in two closely related South African rodents differing in sociality and spatial behaviour.

    PubMed

    Spickett, Andrea; Junker, Kerstin; Krasnov, Boris R; Haukisalmi, Voitto; Matthee, Sonja

    2017-08-01

    To understand the effect of social and spatial behaviour of a host on parasite community organization, we studied species co-occurrence and nestedness of assemblages of gastrointestinal helminths in two closely related rodents, solitary and mobile Rhabdomys dilectus and social and territorially conservative Rhabdomys pumilio, and asked whether helminth communities of the two hosts are characterized by a non-random pattern and whether the occurrence or degree of this non-randomness (a) differs between hosts and (b) is associated with abundance, prevalence and diversity of helminths. We found that although the general pattern of helminth co-occurrence was similar in the two hosts, helminth infracommunities of R. dilectus and R. pumilio differed in the relative frequency of positive and negative pairwise species co-occurrences (only positive in the former and both positive and negative in the latter). Nestedness-related patterns in helminth infracommunities were found in R. pumilio (predominantly anti-nested) but not R. dilectus (predominantly non-nested), whereas the opposite was the case for their component communities (non-nested versus nested, respectively). The level of infection was generally associated with the manifestation of non-randomness in helminth assemblages. Different infection parameters affected different structure patterns in the two hosts. We concluded that community structure of helminths in Rhabdomys spp. results from complex interactions between parasite- and host-associated factors.

  16. Foodborne trematode metacercariae in fish from northern Vietnam and their adults recovered from experimental hamsters.

    PubMed

    Chai, Jong-Yil; De, Nguyen Van; Sohn, Woon-Mok

    2012-12-01

    The prevalence of foodborne trematode (FBT) metacercariae was investigated in fish from 2 localities of northern Vietnam in 2004-2005. Freshwater fish (9 species) were collected from local markets in Hanoi City (n=76) and Nam Dinh Province (n=79), and were examined for FBT metacercariae using the artificial digestion technique. Adult flukes were obtained from hamsters experimentally infected with the metacercariae at day 8 post-infection. Three (Haplorchis pumilio, Centrocestus formosanus, and Procerovum varium) and 6 (Haplorchis taichui, H. pumilio, C. formosanus, P. varium, Stellantchasmus falcatus, and Heterophyopsis continua) species of FBT metacercariae were detected in the 2 regions, respectively. Overall, among the positive fish species, H. pumilio metacercariae were detected in 104 (80.0%) of 130 fish examined (metacercarial density per infected fish; 64.2). C. formosanus metacercariae were found in 37 (40.2%) of 92 fish (metacercarial density; 14.7). P. varium metacercariae were detected in 19 (63.3%) of 30 fish (Anabas testudineus and Mugil cephalus) (metacercarial density; 247.7). S. falcatus metacercariae were found in all 10 M. cephalus examined (metacercarial density; 84.4). H. continua metacercariae (2 in number) were detected in 1 fish of Coilia lindmani. Morphologic characteristics of the FBT metacercariae and their experimentally obtained adults were described. The results have demonstrated that various FBT species are prevalent in northen parts of Vietnam.

  17. An example of the use of forensic palynology in assessing an alibi.

    PubMed

    Mildenhall, Dallas C

    2004-03-01

    A man was found shot in the back on Mount Holdsworth in the Tararua Ranges north of Wellington, the capital city of New Zealand. Police investigations pinpointed one individual who had been seen in the area, knew, and had the means and motive to kill the victim. His alibi was that an eyewitness was mistaken as he never had been in the area and the jacket he was reported to have been wearing had been purchased in The Netherlands and brought to Wellington, where it never had left the city. Furthermore the distinctive board shorts that he was reported to have been wearing had been purchased in a small coastal New Zealand town after the victim had been murdered. Pollen of Nothofagus menziesii, a mountain plant, on the clothing suggested that the alibi was untrue and that the clothing had been in mountains in the vicinity of Mount Holdsworth or a similar mountain scene where Nothofagus menziesii was growing.

  18. Late-glacial and Holocene record of vegetation and climate from Cynthia Bay, Lake St Clair, Tasmania

    NASA Astrophysics Data System (ADS)

    Hopf, F. V. L.; Colhoun, E. A.; Barton, C. E.

    2000-10-01

    A Late-glacial-Holocene pollen record was obtained from a 3.96 m sediment core taken from Lake St Clair, central Tasmania. Modern vegetation and pollen analyses formed the basis for interpretation of the vegetation and climate history. Following deglaciation and before ca. 18450 yr BP Podocarpus lawrencei coniferous heath and Astelia-Plantago wet alpine herbfield became established at Lake St Clair. A distinct Poaceae-Plantago peak occurs between 18450 and 11210 yr BP and a mean annual temperature depression from ca. 6.2°C to 3°C below present is inferred for this period. The marked reduction in Podocarpus and strong increase of Poaceae suggests reduced precipitation levels during the period of widespread deglaciation (ca. 18.5-11 kyr BP). The local Late Pleistocene-Holocene non-forest to forest biostratigraphical boundary is dated at 11.2 kyr BP. It is characterised by expansion of the subalpine taxa Athrotaxis/Diselma with Nothofagus gunnii, and by the establishment of Nothofagus cunninghamii with Eucalyptus spp. A Phyllocladus bulge prior to the expansion of Nothofagus cunninghamii, reported at other Tasmanian sites, is not present at Lake St Clair. Nothofagus cunninghamii cool temperate rainforest peaked at 7800 yr BP, probably under wetter climatic conditions than present. The maximum development of rainforest in the early-middle Holocene may indicate that the temperature was slightly warmer than present, but the evidence is not definitive. The expansion of Eucalyptus spp. and Poaceae after 6000 yr BP may be partly a disclimax effect as a result of Aboriginal burning, but appears also to reflect reduced precipitation. The changes in vegetation and inferred climate can be explained by major changes in synoptic patterns of southern Australia and the adjacent southwest Pacific.

  19. New species of Tomentella (Thelephorales) from the Patagonian Andes forests.

    PubMed

    Kuhar, Francisco; Barroetaveña, Carolina; Rajchenberg, Mario

    2016-01-01

    The genus Tomentella forms abundant ectomycorrhizae in coniferous and deciduous forests worldwide. Molecular identification of root tips suggests undescribed species in the Nothofagus forests of Patagonia, Argentina. Tomentella tenuissima, T. pulvinulata and T. patagonica are described here as new to science based on morphological and molecular analyses. Their host range is addressed using available soil sequences. The identity of previous records of T. galzinii and T. radiosa are discussed with morphological and molecular evidence. © 2016 by The Mycological Society of America.

  20. A new species of Acanthostigma (Tubeufiaceae, Dothideomycetes) from the southern hemisphere.

    PubMed

    Sánchez, R M; Miller, A N; Bianchinotti, M V

    2012-01-01

    A new species belonging to the Dothideomycete genus Acanthostigma is described from bark of two Nothofagus species from Argentina. Its identity as a new species is based on both morphology and molecular sequence data. Acanthostigma patagonica differs from other species in the genus by having larger ascomata and setae and wider, asymmetrical ascospores. An amended key to Acanthostigma species is provided along with a discussion of other species previously described from South America.

  1. Holocene vegetation and climate changes from a peat pollen record of the forest - steppe ecotone, Southwest of Patagonia (Argentina)

    NASA Astrophysics Data System (ADS)

    Mancini, María Virginia

    2009-07-01

    Pollen analysis from a peat-bog sequence located at 50° 24' S, 72° 42' W in the Subantarctic forest - Patagonian steppe ecotone gives information about vegetation and climate changes in Southwestern Patagonia since the glacier retreat. After 11 000 cal yr BP a change from grass steppe to open Nothofagus forest indicates that climatic conditions became rapidly warmer. Development of a closed Nothofagus forest between 5800 and 3200 cal yr BP is interpreted as precipitation increase. During the late Holocene colder climate conditions prevail in response to Neoglacial events. After ca 3000 cal yr BP Nothofagus forest became opener, and after 800 cal yr BP grass steppe expanded. Changes in the forest-steppe ecotone composition as well as the ecotone longitudinal shifts suggest changes in temperature and precipitation. Present-day mean annual precipitation between 300 and 400 mm is associated with grass steppe, and 500-600 mm with a greater forest representation. During the last century, low presence of forest in the area may be related to European settlement and repeated flooding caused by periodic advances of Perito Moreno glacier.

  2. Climate and local controls of long-term vegetation dynamics in northern Patagonia (Lat 41°S)

    NASA Astrophysics Data System (ADS)

    Iglesias, Virginia; Whitlock, Cathy; Bianchi, María Martha; Villarosa, Gustavo; Outes, Valeria

    2012-11-01

    Patagonian vegetation has dramatically changed in composition and distribution over the last 16,000 yr. Although patterns of vegetation change are relatively clear, our understanding of the processes that produce them is limited. High-resolution pollen and charcoal records from two lakes located at lat 41°S provide new information on the postglacial history of vegetation and fire activity at the forest-steppe ecotone, and help clarify the relative importance of local and regional drivers of late-Holocene ecological change. Our results suggest that late-glacial parkland was colonized by shrubs at ca. 11,200 cal yr BP and this vegetation persisted until 4900 cal yr BP, when increased humidity allowed for the establishment of Nothofagus forest. The late Holocene is characterized by oscillations in forest dominance largely driven by changes in humidity, possibly associated with the onset or strengthening of ENSO. In the last 4900 yr, humid periods (4900-3800 and 2850-1350 cal yr BP) have promoted Nothofagus forest, whereas drier times (3800-2850 and 1350-450 cal yr BP) have favored Austrocedrus expansion. At intermediate moisture levels, however, the lower forest supported both taxa, and fire became an important control of community composition, with severe, infrequent fires facilitating Nothofagus regeneration and high fire frequency and intensity supporting Austrocedrus.

  3. Holocene Vegetation and Paleoclimatic and Paleomagnetic History from Lake Johnston, Tasmania

    NASA Astrophysics Data System (ADS)

    Anker, Sharon A.; Colhoun, Eric A.; Barton, Charles E.; Peterson, Mike; Barbetti, Mike

    2001-09-01

    Lake Johnston cirque contains some of the best subalpine rainforest in Tasmania. Pollen from the sediments shows Lagarostrobos franklinii, which presently reaches 1040 m, may be a glacial relict. Nothofagus cunninghamii-Nothofagus gunnii subalpine rainforest developed between 9000 and 6000 14C yr B.P., with a maximum at 8700 14C yr B.P. After 6000 14C yr B.P. Nothofagus gunnii became more important, and from 3600 14C yr B.P. sclerophyll and heath components increased. Partial burning of the catchment occurred periodically. Early Holocene climate was warmer and wetter than late Holocene climate. The vegetation and climate changes are similar to those recorded from western South Island New Zealand and Chile. Radiocarbon dates give a sedimentation rate of 0.43 mm/yr. Cores are correlated by magnetic susceptibility. Magnetic ages are assigned by matching with the 14C-dated secular variation master curve for southeastern Australia. Magnetic ages are consistent with the 14C chronology when the former are adjusted by 350 years.

  4. Trajectories associated to regional and extra-regional pollen transport in the southeast of Buenos Aires province, Mar del Plata (Argentina).

    PubMed

    Gassmann, María I; Pérez, Claudio F

    2006-05-01

    Long range transport of airborne pollen has been seldom studied in South America. Backward trajectories of Celtis and Nothofagus pollen grains trapped over a meteorological station outside Mar del Plata City were calculated in one-hour steps using the regional hybrid model developed by the NOAA (HYSPLIT 4.5) and the data of the NCEP filed in the NOAA server. Results showed that the observed trajectories agree with the location of vegetation sources of the collected tree species. In the case of Celtis, the transport was associated to anticyclones located east of the city, generating winds with a N-NE component, which produce pollen cloud advection from the Celtis forests located some tens of kilometers to the N and NE of the city. The sources of Nothofagus pollen correspond to a narrow strip on the Andes slopes between 39 degrees and 55 degrees S, at least 1100 km to the SW of Mar del Plata. The transport was associated to eastward displacement of the troughs corresponding to the Westerlies circulation and the presence of an anticyclone system that brings back Nothofagus pollen towards Mar del Plata area.

  5. Holocene vegetation and climate change in southern New Zealand: linkages between forest composition and quantitative surface moisture reconstructions from an ombrogenous bog

    NASA Astrophysics Data System (ADS)

    Wilmshurst, Janet M.; McGlone, Matt S.; Charman, Dan J.

    2002-10-01

    This paper presents a Holocene pollen record from an ombrotrophic bog in Southland, New Zealand, together with multiproxy data (testate amoebae, peat humification and plant macrofossils) from the same core to establish an independent semiquantitative record of peatland surface moisture. Linkages between reconstructed peatland surface moisture and regional forest composition are investigated using redundancy analysis of the forest pollen data constrained with predicted bog water-table depths. Over 32% of the pollen data variance can be explained by surface moisture changes in the bog, suggesting a common cause of water-table and regional vegetation change. Water tables were higher during the early to mid-Holocene when the forest was dominated by podocarp taxa. Water tables lowered after about 3300 cal. yr BP coevally with the expansion of Nothofagus species, culminating with the dominance of Nothofagus subgenus Fuscospora in the past 1200 cal. yr BP. This is in apparent opposition to the warm/dry to cool/wet trend suggested by subjective interpretation of pollen data alone, from this and other studies. We suggest that during the late Holocene, drier summers associated with shifts in solar insolation caused reduced surface wetness and summer humidity, which together with a trend to cooler winters, apparently favoured the regeneration of Nothofagus species.

  6. Environmental and climatic changes in Central Chilean Patagonia since the Late Glacial (Mallín El Embudo, 44° S)

    NASA Astrophysics Data System (ADS)

    de Porras, M. E.; Maldonado, A.; Quintana, F. A.; Martel-Cea, A.; Reyes, O.; Méndez, C.

    2013-10-01

    Multi-millennial environmental and climatic changes in Central Chilean Patagonia (44-49° S) during the Last Glacial-Interglacial cycle have been of particular interest as changes in the position and strength of the Southern Westerlies are the major forcing factor conditioning the environmental dynamics. Recent attempts to reconstruct regional environmental and climatic signals from Central Chilean Patagonia reveal some discrepancies and unclear issues among the records. This paper presents the 13 ka pollen and charcoal records from Mallín El Embudo (44°40' S; 71°42' W) located in the deciduous Nothofagus forest in the middle Río Cisnes valley. The paper aims to (1) establish the timing and magnitude of local vegetation changes and fire activity since the Late Glacial and (2) integrate these results at the regional scale in order to discuss the discrepancies and depict the Central Chilean Patagonia environmental and climatic dynamics since Late Glacial. Open landscapes dominated by grasses associated with scattered Nothofagus forest patches dominated middle Río Cisnes valley between 13-11.2 ka suggesting low effective moisture but also reflecting that landscape configuration after glacial retreat was still ongoing. At 11.2 ka, a sudden development of an open and quite dynamic Nothofagus forest probably associated to the synchronous high fire activity occurred suggesting a rise in effective moisture. Since 9.5 ka, the record reflects the presence of a closed Nothofagus forest related to higher/similar effective moisture conditions than before but under an unmarked precipitation seasonality. The forest experienced a slight canopy opening since 5.7 ka, probably due to slightly drier conditions than before followed by a sudden change around 4.2 ka associated with fire and volcanic disturbances. The recovery of an open Nothofagus forest related to slight wetter conditions (similar to present) occurred around 2 ka and persisted under highly variable climatic

  7. Environmental and climatic changes in central Chilean Patagonia since the Late Glacial (Mallín El Embudo, 44° S)

    NASA Astrophysics Data System (ADS)

    de Porras, M. E.; Maldonado, A.; Quintana, F. A.; Martel-Cea, A.; Reyes, O.; Méndez, C.

    2014-05-01

    Multi-millennial environmental and climatic changes in central Chilean Patagonia (44-49° S) during the Last Glacial-Interglacial cycle have been of particular interest as changes in the position and strength of the southern westerlies are the major forcing factor conditioning the environmental dynamics. Recent attempts to reconstruct regional environmental and climatic signals from central Chilean Patagonia reveal some discrepancies and unclear issues among the records. This paper presents the 13 ka pollen and charcoal records from Mallín El Embudo (44° 40' S, 71° 42' W) located in the deciduous Nothofagus forest in the middle Río Cisnes valley. The paper aims to (1) establish the timing and magnitude of local vegetation changes and fire activity since the Late Glacial and (2) integrate these results at the regional scale in order to discuss the discrepancies and depict the environmental and climatic dynamics in central Chilean Patagonia since the Late Glacial. Open landscapes dominated by grasses associated with scattered Nothofagus forest patches dominated the middle Río Cisnes valley between 13 and 11.2 ka suggesting low effective moisture but also indicating that landscape configuration after glacial retreat was still ongoing. At 11.2 ka, the sudden development of an open and quite dynamic Nothofagus forest probably associated with the synchronous high fire activity occurred, suggesting a rise in effective moisture associated with dry summers. Since 9.5 ka, the record reflects the presence of a closed Nothofagus forest related to higher effective moisture conditions than before combined with moderate dry summers that may have triggered a high frequency of low-magnitude crown fires that did not severely affect the forest. The forest experienced a slight canopy opening after 5.7 ka, probably due to slightly drier conditions than before followed by a sudden change to open forest conditions around 4.2 ka associated with fire and volcanic disturbances. Around

  8. Dynamic regulation of mRNA decay during neural development.

    PubMed

    Burow, Dana A; Umeh-Garcia, Maxine C; True, Marie B; Bakhaj, Crystal D; Ardell, David H; Cleary, Michael D

    2015-04-21

    Gene expression patterns are determined by rates of mRNA transcription and decay. While transcription is known to regulate many developmental processes, the role of mRNA decay is less extensively defined. A critical step toward defining the role of mRNA decay in neural development is to measure genome-wide mRNA decay rates in neural tissue. Such information should reveal the degree to which mRNA decay contributes to differential gene expression and provide a foundation for identifying regulatory mechanisms that affect neural mRNA decay. We developed a technique that allows genome-wide mRNA decay measurements in intact Drosophila embryos, across all tissues and specifically in the nervous system. Our approach revealed neural-specific decay kinetics, including stabilization of transcripts encoding regulators of axonogenesis and destabilization of transcripts encoding ribosomal proteins and histones. We also identified correlations between mRNA stability and physiologic properties of mRNAs; mRNAs that are predicted to be translated within axon growth cones or dendrites have long half-lives while mRNAs encoding transcription factors that regulate neurogenesis have short half-lives. A search for candidate cis-regulatory elements identified enrichment of the Pumilio recognition element (PRE) in mRNAs encoding regulators of neurogenesis. We found that decreased expression of the RNA-binding protein Pumilio stabilized predicted neural mRNA targets and that a PRE is necessary to trigger reporter-transcript decay in the nervous system. We found that differential mRNA decay contributes to the relative abundance of transcripts involved in cell-fate decisions, axonogenesis, and other critical events during Drosophila neural development. Neural-specific decay kinetics and the functional specificity of mRNA decay suggest the existence of a dynamic neurodevelopmental mRNA decay network. We found that Pumilio is one component of this network, revealing a novel function for this RNA

  9. Permanent Genetic Resources added to Molecular Ecology Resources Database 1 December 2009-31 January 2010.

    PubMed

    Anderson, Cynthia M; Aparicio, Gallego J; Atangana, Alain R; Beaulieu, Jean; Bruford, M W; Cain, Forrest; Campos, T; Cariani, A; Carvalho, M A; Chen, Nan; Chen, P P; Clamens, A-L; Clark, Ann M; Coeur D'Acier, A; Connolly, Paul; Cordero-Rivera, Adolfo; Coughlan, James P; Cross, Thomas S; David, Bruno; DE Bruyn, Colin; DE Meyer, M; DE Ridder, Chantal; Delatte, H; Dettori, M T; Downer, S J; Dubreuil, Christine; Evans, K J; Fan, Bin; Ferrara, G; Gagné, André; Gaillard, Maria; Gigliarelli, L; Giovinazzi, J; Gomez, D R; Grünwald, N J; Hansson, Bengt; Huotari, T; Jank, L; Jousselin, E; Jungmann, L; Kaczmarek, M E; Khasa, Damase P; Kneebone, Jeff; Korpelainen, H; Kostamo, K; Lanfaloni, L; Lin, Haoran; Liu, Xiaochun; Lucentini, L; Maes, G E; Mahaffee, W F; Meng, Zining; Micali, S; Milano, I; Mok, H F; Morin, L; Neill, T M; Newton, Craig H; Gigi Ostrow, D; Palomba, A; Panara, F; Puletti, M E; Quarta, R; Quilici, S; Ramos, A K B; Rigaud, Thierry; Risterucci, A M; Salomon, Matthew P; Sánchez-Guillén, Rosa A; Sarver, Shane K; Sequeira, A S; Sforça, D A; Simiand, C; Smith, Brian; Sousa, A C B; Souza, A P; Stepien, C C; Stuckert, A J; Sulikowski, James; Tayeh, A; Tinti, F; Tsang, Paul C W; VAN Houdt, J K J; Vendramin, E; Verde, I; Virgilio, M; Wang, Huan L; Wang, L E; Wattier, Rémi A; Wellenreuther, Maren; Xie, Cong X; Zane, L; Zhang, Xiu J; Zhang, Yong; Zhuang, Zhimeng; Zucchi, M I

    2010-05-01

    This article documents the addition of 220 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Allanblackia floribunda, Amblyraja radiata, Bactrocera cucurbitae, Brachycaudus helichrysi, Calopogonium mucunoides, Dissodactylus primitivus, Elodea canadensis, Ephydatia fluviatilis, Galapaganus howdenae howdenae, Hoplostethus atlanticus, Ischnura elegans, Larimichthys polyactis, Opheodrys vernalis, Pelteobagrus fulvidraco, Phragmidium violaceum, Pistacia vera, and Thunnus thynnus. These loci were cross-tested on the following species: Allanblackia gabonensis, Allanblackia stanerana, Neoceratitis cyanescens, Dacus ciliatus, Dacus demmerezi, Bactrocera zonata, Ceratitis capitata, Ceratitis rosa, Ceratits catoirii, Dacus punctatifrons, Ephydatia mülleri, Spongilla lacustris, Geodia cydonium, Axinella sp., Ischnura graellsii, Ischnura ramburii, Ischnura pumilio, Pistacia integerrima and Pistacia terebinthus.

  10. Opisthorchis viverrini metacercaria in Thai freshwater fish.

    PubMed

    Waikagul, J

    1998-06-01

    Examination for metacercaria in freshwater fish, the common intermediate hosts of Opisthorchis viverrini was carried out during 1992-1996. The 4-year survey of fish from markets in 14 provinces revealed that metacercariae of O. viverrini were found in fish from Udon Thani, Sa Kaeo and Prachin Buri Provinces; fish from Aranyaprathet district had the highest positive rates (25-28%). Fish from 12 provinces were found to be positive with heterophyid metacercariae, namely: Haplorchis pumilio, H. taichui, H. yokogawai, Stellantchasmus falcatus, Centrocestus formosanus and Haplorchoides cahirinus. It was also observed that the prevalence of O. viverrini metacercaria in fish decreased markedly during the last 10 years.

  11. Lamprops donghaensis sp. n. (Crustacea, Cumacea, Lampropidae), a new species from Korean waters

    PubMed Central

    Kim, Sung-Hyun; Kim, Young-Hyo

    2015-01-01

    Abstract A new species of Cumacea belonging to the genus Lamprops Sars was collected from the East Sea of Korea. This new species resembles Lamprops comatus Zimmer, Lamprops carinatus Hart, Lamprops flavus Harada, Lamprops pumilio Zimmer, Lamprops tomalesi Gladfelter, and Lamprops obfuscatus (Gladfelter) in lacking lateral oblique ridges on the carapace and lateral setae on the telson. The new species, however, is distinguished from its congeners by having a dorsal concave groove and a lateral rounded depressed area on pereonite 2. The new species is fully illustrated and compared with related species. A key to the world Lamprops species lacking lateral ridges on the carapace is also provided. PMID:26312026

  12. Every which way – nanos gene regulation in echinoderms

    PubMed Central

    Oulhen, Nathalie; Wessel, Gary M.

    2014-01-01

    Nanos is an essential factor of germ line success in all animals tested. This gene encodes a Zn-finger RNA-binding protein that in complex with its partner pumilio, binds to and changes the fate of several known transcripts. We summarize here the documented functions of nanos in several key organisms, and then emphasize echinoderms as a working model for how nanos expression is regulated. Nanos presence outside of the target cells is often detrimental to the animal, and in sea urchins, nanos expression appears to be regulated at every step of transcription, and post-transcriptional activity, making this gene product exciting, every which way. PMID:24376110

  13. Every which way--nanos gene regulation in echinoderms.

    PubMed

    Oulhen, Nathalie; Wessel, Gary M

    2014-03-01

    Nanos is an essential factor of germ line success in all animals tested. This gene encodes a Zn-finger RNA-binding protein that in complex with its partner pumilio binds to and changes the fate of several known transcripts. We summarize here the documented functions of Nanos in several key organisms, and then emphasize echinoderms as a working model for how nanos expression is regulated. Nanos presence outside of the target cells is often detrimental to the animal, and in sea urchins, nanos expression appears to be regulated at every step of transcription, and post-transcriptional activity, making this gene product exciting, every which way.

  14. Holocene climate variability and environmental history at the Patagonian forest/steppe ecotone: Lago Mosquito (lat. 42.50°S, long. 71.40°W) and Laguna del Cóndor (lat. 42.20°S, long. 71.17°W)

    NASA Astrophysics Data System (ADS)

    Iglesias, V.; Whitlock, C. L.; Bianchi, M. M.

    2010-12-01

    Along the eastern Andes, a sharp ecotone separates steppe from North Patagonian forest dominated by Nothofagus spp. and Austrocedrus chilensis. The elevational position of the ecotone is determined by effective moisture, which in turn is governed by the strength and latitudinal position of the Southern Westerlies. As a result, past changes in ecotone position and composition, and fire activity provide an opportunity to examine past climate variations. Holocene environmental history at two sites in close proximity along a west-to-east moisture gradient is inferred from magnetic susceptibility, pollen and high-resolution charcoal data. Comparison of the two records enhanced the spatial resolution of the reconstruction. Pollen data suggest that, prior to 9 ka, vegetation resembled a modern steppe, in accordance with the widespread aridity characteristic of the period. Fires were infrequent, likely as a consequence of fuel discontinuity associated with low vegetation cover. At 9 ka, forest taxa expanded into the steppe. This change in community composition was reflected in the fire regime: fires became more frequent and biomass burning increased. This fire-vegetation linkage suggests that summers were arid enough to support fires but moisture was sufficient for Nothofagus forest to expand. Based on a westward displacement of the forest-steppe ecotone, drier-than-before conditions are inferred for the 5.5-3.7 ka period. A shift from crown to surface fires at the westernmost site, and lengthening fire return intervals towards the east accompanied this vegetation change. Between 3.7 and 2.4 ka, both sites registered an A. chilensis expansion, suggesting an increase in effective moisture. The last 2400 years are characterized by uninterrupted advances of Nothofagus forest. Ecotonal trees and shrubs, such as A. chilensis, Maytenus boaria and Rhamnaceae, have become less abundant, suggesting a recent trend towards cooler and/or wetter conditions.

  15. High prevalence of liver and intestinal fluke infections among residents of Savannakhet Province in Laos.

    PubMed

    Chai, Jong-Yil; Han, Eun-Taek; Guk, Sang-Mee; Shin, Eun-Hee; Sohn, Woon-Mok; Yong, Tai-Soon; Eom, Keeseon S; Lee, Keon-Hoon; Jeong, Hoo-Gn; Ryang, Yong-Sang; Hoang, Eui-Hyug; Phommasack, Bounlay; Insisiengmay, Bounnaloth; Lee, Soon-Hyung; Rim, Han-Jong

    2007-09-01

    The prevalence of liver and intestinal fluke infections was surveyed on residents of Savannakhet Province, Laos. Fecal specimens were collected from a total of 981 residents in 4 Mekong riverside villages and examined by the Kato-Katz thick smear technique. The results revealed that the overall helminth egg positive rate was 84.2%, and the positive rate for small trematode eggs, including Opisthorchis viverrini, heterophyids, or lecithodendriids, was 67.1%. To obtain adult flukes, 38 small trematode egg positive cases were treated with a 20-30 mg/kg single dose of praziquantel and purged. Diarrheic stools were then collected from 29 people and searched for helminth parasites using stereomicroscopes. Mixed infections with O. viverrini and 6 kinds of intestinal flukes were found, namely, Haplorchis taichui, Haplorchis pumilio, Haplorchis yokogawai, Prosthodendrium molenkampi, Phaneropsolus bonnei, and echinostomes. The total number of flukes collected was 7,693 specimens (av. no. per treated person; 265.3). The most common species was O. viverrini, followed by H. taichui, P. molenkampi, echinostomes, H. pumilio, P. bonnei, and H. yokogawai. The results indicate that foodborne liver and intestinal fluke infections are prevalent among residents of Savannakhet Province, Laos.

  16. High prevalence of liver and intestinal fluke infections among residents of Savannakhet Province in Laos

    PubMed Central

    Han, Eun-Taek; Guk, Sang-Mee; Shin, Eun-Hee; Sohn, Woon-Mok; Yong, Tai-Soon; Eom, Keeseon S.; Lee, Keon-Hoon; Jeong, Hoo-Gn; Ryang, Yong-Sang; Hoang, Eui-Hyug; Phommasack, Bounlay; Insisiengmay, Bounnaloth; Lee, Soon-Hyung; Rim, Han-Jong

    2007-01-01

    The prevalence of liver and intestinal fluke infections was surveyed on residents of Savannakhet Province, Laos. Fecal specimens were collected from a total of 981 residents in 4 Mekong riverside villages and examined by the Kato-Katz thick smear technique. The results revealed that the overall helminth egg positive rate was 84.2%, and the positive rate for small trematode eggs, including Opisthorchis viverrini, heterophyids, or lecithodendriids, was 67.1%. To obtain adult flukes, 38 small trematode egg positive cases were treated with a 20-30 mg/kg single dose of praziquantel and purged. Diarrheic stools were then collected from 29 people and searched for helminth parasites using stereomicroscopes. Mixed infections with O. viverrini and 6 kinds of intestinal flukes were found, namely, Haplorchis taichui, Haplorchis pumilio, Haplorchis yokogawai, Prosthodendrium molenkampi, Phaneropsolus bonnei, and echinostomes. The total number of flukes collected was 7,693 specimens (av. no. per treated person; 265.3). The most common species was O. viverrini, followed by H. taichui, P. molenkampi, echinostomes, H. pumilio, P. bonnei, and H. yokogawai. The results indicate that foodborne liver and intestinal fluke infections are prevalent among residents of Savannakhet Province, Laos. PMID:17876167

  17. Nop9 is a PUF-like protein that prevents premature cleavage to correctly process pre-18S rRNA

    PubMed Central

    Zhang, Jun; McCann, Kathleen L.; Qiu, Chen; Gonzalez, Lauren E.; Baserga, Susan J.; Hall, Traci M. Tanaka

    2016-01-01

    Numerous factors direct eukaryotic ribosome biogenesis, and defects in a single ribosome assembly factor may be lethal or produce tissue-specific human ribosomopathies. Pre-ribosomal RNAs (pre-rRNAs) must be processed stepwise and at the correct subcellular locations to produce the mature rRNAs. Nop9 is a conserved small ribosomal subunit biogenesis factor, essential in yeast. Here we report a 2.1-Å crystal structure of Nop9 and a small-angle X-ray-scattering model of a Nop9:RNA complex that reveals a ‘C'-shaped fold formed from 11 Pumilio repeats. We show that Nop9 recognizes sequence and structural features of the 20S pre-rRNA near the cleavage site of the nuclease, Nob1. We further demonstrate that Nop9 inhibits Nob1 cleavage, the final processing step to produce mature small ribosomal subunit 18S rRNA. Together, our results suggest that Nop9 is critical for timely cleavage of the 20S pre-rRNA. Moreover, the Nop9 structure exemplifies a new class of Pumilio repeat proteins. PMID:27725644

  18. Patterns of second-to-fourth digit length ratios (2D:4D) in two species of frogs and two species of lizards at La Selva, Costa Rica.

    PubMed

    Direnzo, Graziella Vittoria; Stynoski, Jennifer Lynn

    2012-04-01

    It is now well documented that androgen and estrogen signaling during early development cause a sexual dimorphism in second-to-fourth digit length ratio (2D:4D). It is also well documented that males of mammalian species have a smaller 2D:4D than females. Although there are discrepancies among 2D:4D studies in birds, the consensus is that birds exhibit the opposite pattern with males having a larger 2D:4D than females. The literature currently lacks substantial information regarding the phylogenetic pattern of this trait in amphibians and reptiles. In this study, we examined 2D:4D in two species of frogs (Oophaga pumilio and Craugastor bransfordii) and two species of lizards (Anolis humilis and Anolis limifrons) to determine the existence and the pattern of the sexual dimorphism. Male O. pumilio and C. bransfordii displayed larger 2D:4D than females in at least one of their two forelimbs. Male A. humilis had larger 2D:4D than females in both hindlimbs, but smaller 2D:4D than females in both forelimbs. Male A. limifrons may also have smaller 2D:4D than females in the right forelimb. Finally, digit ratios were sometimes positively related to body length, suggesting allometric growth. Overall, our results support the existence of the 2D:4D sexual dimorphism in amphibians and lizards and add to the knowledge of 2D:4D trait patterning among tetrapods. Copyright © 2012 Wiley Periodicals, Inc.

  19. Poison frog colors are honest signals of toxicity, particularly for bird predators.

    PubMed

    Maan, Martine E; Cummings, Molly E

    2012-01-01

    Antipredator defenses and warning signals typically evolve in concert. However, the extensive variation across taxa in both these components of predator deterrence and the relationship between them are poorly understood. Here we test whether there is a predictive relationship between visual conspicuousness and toxicity levels across 10 populations of the color-polymorphic strawberry poison frog, Dendrobates pumilio. Using a mouse-based toxicity assay, we find extreme variation in toxicity between frog populations. This variation is significantly positively correlated with frog coloration brightness, a viewer-independent measure of visual conspicuousness (i.e., total reflectance flux). We also examine conspicuousness from the view of three potential predator taxa, as well as conspecific frogs, using taxon-specific visual detection models and three natural background substrates. We find very strong positive relationships between frog toxicity and conspicuousness for bird-specific perceptual models. Weaker but still positive correlations are found for crab and D. pumilio conspecific visual perception, while frog coloration as viewed by snakes is not related to toxicity. These results suggest that poison frog colors can be honest signals of prey unpalatability to predators and that birds in particular may exert selection on aposematic signal design. © 2011 by The University of Chicago.

  20. Only distance matters – non-choosy females in a poison frog population

    PubMed Central

    2013-01-01

    Background Females have often been shown to exhibit preferences for certain male traits. However, little is known about behavioural rules females use when searching for mates in their natural habitat. We investigated mate sampling tactics and related costs in the territorial strawberry poison frog (Oophaga pumilio) possessing a lek-like mating system, where both sequential and simultaneous sampling might occur. We continuously monitored the sampling pattern and behaviour of females during the complete period between two successive matings. Results We found no evidence that females compared males by visiting them. Instead females mated with the closest calling male irrespective of his acoustic and physical traits, and territory size. Playback experiments in the natural home ranges of receptive females revealed that tested females preferred the nearest speaker and did not discriminate between low and high call rates or dominant frequencies. Conclusions Our results suggest that females of O. pumilio prefer the closest calling male in the studied population. We hypothesize that the sampling tactic in this population is affected by 1) a strongly female biased sex ratio and 2) a low variance in traits of available males due to strong male-male competition, preventing low quality males from defending a territory and mating. PMID:23688371

  1. Only distance matters - non-choosy females in a poison frog population.

    PubMed

    Meuche, Ivonne; Brusa, Oscar; Linsenmair, K Eduard; Keller, Alexander; Pröhl, Heike

    2013-05-20

    Females have often been shown to exhibit preferences for certain male traits. However, little is known about behavioural rules females use when searching for mates in their natural habitat. We investigated mate sampling tactics and related costs in the territorial strawberry poison frog (Oophaga pumilio) possessing a lek-like mating system, where both sequential and simultaneous sampling might occur. We continuously monitored the sampling pattern and behaviour of females during the complete period between two successive matings. We found no evidence that females compared males by visiting them. Instead females mated with the closest calling male irrespective of his acoustic and physical traits, and territory size. Playback experiments in the natural home ranges of receptive females revealed that tested females preferred the nearest speaker and did not discriminate between low and high call rates or dominant frequencies. Our results suggest that females of O. pumilio prefer the closest calling male in the studied population. We hypothesize that the sampling tactic in this population is affected by 1) a strongly female biased sex ratio and 2) a low variance in traits of available males due to strong male-male competition, preventing low quality males from defending a territory and mating.

  2. PUF proteins: Cellular functions and potential applications.

    PubMed

    Kiani, Seyed Jalal; Taheri, Tahereh; Rafati, Sima; Samimi-Rad, Katayoun

    2016-09-14

    RNA-binding proteins play critical roles in the regulation of gene expression. Among several families of RNA-binding proteins, PUF (Pumilio and FBF) proteins have been the subject of extensive investigations, as they can bind RNA in a sequence-specific manner and they are evolutionarily conserved among a wide range of organisms. The outstanding feature of these proteins is a highly conserved RNA-binding domain, which is known as the Pumilio-homology domain (PUM-HD) that mostly consists of eight tandem repeats. Each repeat recognizes an RNA base with a simple three-letter code that can be programmed in order to change the sequence-specificity of the protein. Using this tailored architecture, researchers have been able to change the specificity of the PUM-HD and target desired transcripts in the cell, even in subcellular compartments. The potential applications of this versatile tool in molecular cell biology seem unbounded and the use of these factors in pharmaceutics might be an interesting field of study in near future.

  3. Formicine ants: An arthropod source for the pumiliotoxin alkaloids of dendrobatid poison frogs

    PubMed Central

    Saporito, Ralph A.; Garraffo, H. Martin; Donnelly, Maureen A.; Edwards, Adam L.; Longino, John T.; Daly, John W.

    2004-01-01

    A remarkable diversity of bioactive lipophilic alkaloids is present in the skin of poison frogs and toads worldwide. Originally discovered in neotropical dendrobatid frogs, these alkaloids are now known from mantellid frogs of Madagascar, certain myobatrachid frogs of Australia, and certain bufonid toads of South America. Presumably serving as a passive chemical defense, these alkaloids appear to be sequestered from a variety of alkaloid-containing arthropods. The pumiliotoxins represent a major, widespread, group of alkaloids that are found in virtually all anurans that are chemically defended by the presence of lipophilic alkaloids. Identifying an arthropod source for these alkaloids has been a considerable challenge for chemical ecologists. However, an extensive collection of neotropical forest arthropods has now revealed a putative arthropod source of the pumiliotoxins. Here we report on the presence of pumiliotoxins in formicine ants of the genera Brachymyrmex and Paratrechina, as well as the presence of these ants in the stomach contents of the microsympatric pumiliotoxin-containing dendrobatid frog, Dendrobates pumilio. These pumiliotoxins are major alkaloids in D. pumilio, and Brachymyrmex and Paratrechina ants now represent the only known dietary sources of these toxic alkaloids. These findings further support the significance of ant-specialization and alkaloid sequestration in the evolution of bright warning coloration in poison frogs and toads. PMID:15128938

  4. Studies on some fish parasites of public health importance in the southern area of Saudi Arabia.

    PubMed

    Khalil, Mokhtar Ibrahim; El-Shahawy, Ismail Saad; Abdelkader, Hussein Saad

    2014-01-01

    The present study was the first attempt to survey the diversity of fish zoonotic parasites in the southern region of Saudi Arabia, particularly the Najran area, from October 2012 to October 2013. Approximately 163 fish representing seven species (two of freshwater fish and five of marine fish) were examined for fish-borne trematode metacercariae using the compression technique, and for zoonotic nematode larvae. Adult flukes were obtained from cats experimentally infected with the metacercariae on day 25 post-infection The prevalence of each parasite species was recorded. The parasites found belonged to two taxa: Digenea (Heterophyes heterophyes and Haplorchis pumilio) in muscle tissue; and nematodes (larvae of Capillaria sp.) in the digestive tract. The morphological characteristics of the fish-borne trematode metacercariae and their experimentally obtained adults were described. This is the first report of these parasites in fish in Saudi Arabia. Moreover, Myripristis murdjan presented higher prevalence of Capillaria sp. infection (22.7%), while Haplorchis pumilio was the dominant metacercarial species (7.9%). Although the number of documented cases continues to increase, the overall risk of human infection is slight. The increasing exploitation of the marine environment by humans and the tendency to reduce cooking times when preparing seafood products both increase the chances of becoming infected with these parasites. Furthermore, our results indicate that certain fish production systems are at risk of presenting fish zoonotic parasites, and that control approaches will benefit from understanding these risk factors.

  5. Programmable RNA-binding protein composed of repeats of a single modular unit

    PubMed Central

    Adamala, Katarzyna P.; Martin-Alarcon, Daniel A.; Boyden, Edward S.

    2016-01-01

    The ability to monitor and perturb RNAs in living cells would benefit greatly from a modular protein architecture that targets unmodified RNA sequences in a programmable way. We report that the RNA-binding protein PumHD (Pumilio homology domain), which has been widely used in native and modified form for targeting RNA, can be engineered to yield a set of four canonical protein modules, each of which targets one RNA base. These modules (which we call Pumby, for Pumilio-based assembly) can be concatenated in chains of varying composition and length, to bind desired target RNAs. The specificity of such Pumby–RNA interactions was high, with undetectable binding of a Pumby chain to RNA sequences that bear three or more mismatches from the target sequence. We validate that the Pumby architecture can perform RNA-directed protein assembly and enhancement of translation of RNAs. We further demonstrate a new use of such RNA-binding proteins, measurement of RNA translation in living cells. Pumby may prove useful for many applications in the measurement, manipulation, and biotechnological utilization of unmodified RNAs in intact cells and systems. PMID:27118836

  6. Stonewalling Drosophila stem cell differentiation by epigenetic controls.

    PubMed

    Maines, Jean Z; Park, Joseph K; Williams, Meredith; McKearin, Dennis M

    2007-04-01

    During Drosophila oogenesis, germline stem cell (GSC) identity is maintained largely by preventing the expression of factors that promote differentiation. This is accomplished via the activity of several genes acting either in the GSC or in its niche. The translational repressors Nanos and Pumilio act in GSCs to prevent differentiation, probably by inhibiting the translation of early differentiation factors, whereas niche signals prevent differentiation by silencing transcription of the differentiation factor Bam. We have found that the DNA-associated protein Stonewall (Stwl) is also required for GSC maintenance. stwl is required cell-autonomously; clones of stwl(-) germ cells were lost by differentiation, and ectopic Stwl caused an expansion of GSCs. stwl mutants acted as Suppressors of variegation, indicating that stwl normally acts in chromatin-dependent gene repression. In contrast to several previously described GSC maintenance factors, Stwl probably functions epigenetically to prevent GSC differentiation. Stwl-dependent transcriptional repression does not target bam, but rather Stwl represses the expression of many genes, including those that may be targeted by Nanos and Pumilio translational inhibition.

  7. Nop9 is a PUF-like protein that prevents premature cleavage to correctly process pre-18S rRNA

    SciTech Connect

    Zhang, Jun; McCann, Kathleen L.; Qiu, Chen; Gonzalez, Lauren E.; Baserga, Susan J.; Hall, Traci M. Tanaka

    2016-10-11

    Numerous factors direct eukaryotic ribosome biogenesis, and defects in a single ribosome assembly factor may be lethal or produce tissue-specific human ribosomopathies. Pre-ribosomal RNAs (pre-rRNAs) must be processed stepwise and at the correct subcellular locations to produce the mature rRNAs. Nop9 is a conserved small ribosomal subunit biogenesis factor, essential in yeast. Here we report a 2.1-Å crystal structure of Nop9 and a small-angle X-ray-scattering model of a Nop9:RNA complex that reveals a ‘C’-shaped fold formed from 11 Pumilio repeats. We show that Nop9 recognizes sequence and structural features of the 20S pre-rRNA near the cleavage site of the nuclease, Nob1. We further demonstrate that Nop9 inhibits Nob1 cleavage, the final processing step to produce mature small ribosomal subunit 18S rRNA. Together, our results suggest that Nop9 is critical for timely cleavage of the 20S pre-rRNA. Moreover, the Nop9 structure exemplifies a new class of Pumilio repeat proteins.

  8. Pollen evidence for variations in the southern margin of the westerly winds in SW Patagonia over the last 12,600 years

    NASA Astrophysics Data System (ADS)

    Villa-Martínez, Rodrigo; Moreno, Patricio I.

    2007-11-01

    We report pollen and charcoal records from Vega Ñandú (˜ 51°0'S, 72°45'W), a small mire located near the modern forest-steppe ecotone in Torres del Paine National Park, southern Chile. The record shows an open landscape dominated by low shrubs and herbs between 12,600 and 10,800 cal yr BP, under cold and relatively humid conditions. Nothofagus experienced frequent, large-amplitude oscillations between 10,800 and 6800 cal yr BP, indicating recurrent transitions between shrubland/parkland environments, under warm and highly variable moisture conditions. A sustained increase in Nothofagus started at 6800 cal yr BP, punctuated by step-wise increases at 5100 and 2400 cal yr BP, implying further increases in precipitation. We interpret these results as indicative of variations in the amount of precipitation of westerly origin, with prominent increases at 6800, 5100, and 2400 cal yr BP. These pulses led to peak precipitation regimes during the last two millennia in this part of SW Patagonia. Our data suggest variations in the position and/or strength of the southern margin of the westerlies, most likely linked to variations in the extent and/or persistence of sea ice and sea-surface temperature anomalies in the Southern Ocean. Over the last two centuries the record shows a forest decline and expansion of Rumex acetosella, an exotic species indicative of European disturbance.

  9. Late quaternary vegetation of southern Isla Grande de Chiloñ, Chile

    NASA Astrophysics Data System (ADS)

    Villagran, Carolina

    1988-05-01

    Late-glacial-Holocene forest history of southern Isla Chiloé (latitude 43°10' S) was reconstructed on the basis of pollen analysis in three profiles (Laguna Soledad, Laguna Chaiguata, Puerto Carmen). Prior to 12,500 yr B.P. pollen records are dominated by plant taxa characteristic of open habitats (Zone I). From 12,500 yr B.P. to the present, tree species predominate in the pollen records (Zones II-V). Between 12,500 and 9500 yr B.P. ombrophyllous taxa ( Nothofagus, Podocarpus nubigena. Myrtaceae, Fitzroya/Pilgerodendron, and Drimys) are frequent in all pollen diagrams, suggesting a wetter and colder climate than the present. Between 9000 and 5500 yr B.P. Valdivian forest elements, such as Nothofagus dombeyi type, Weinmannia, and Eucryphia/Caldcluvia, dominate, indicating a period of drier and warmer climate. From 5500 yr B.P. onward, the expansion of mixed North Patagonian-Subantarctic forest elements and the increased frequence of Tepualia suggest increased rainfall and temperatures oscillating around the modern values. The change from open to forest vegetation (ca. 12,500 yr B.P.) probably represents the most pronounced climatic change in the record and can be interpreted as the glacial-postglacial transition in the study area.

  10. Heavy metal and trace elements in riparian vegetation and macrophytes associated with lacustrine systems in Northern Patagonia Andean Range.

    PubMed

    Juárez, Andrea; Arribére, María A; Arcagni, Marina; Williams, Natalia; Rizzo, Andrea; Ribeiro Guevara, Sergio

    2016-09-01

    Vegetation associated with lacustrine systems in Northern Patagonia was studied for heavy metal and trace element contents, regarding their elemental contribution to these aquatic ecosystems. The research focused on native species and exotic vascular plant Salix spp. potential for absorbing heavy metals and trace elements. The native species studied were riparian Amomyrtus luma, Austrocedrus chilensis, Chusquea culeou, Desfontainia fulgens, Escallonia rubra, Gaultheria mucronata, Lomatia hirsuta, Luma apiculata, Maytenus boaria, Myrceugenia exsucca, Nothofagus antarctica, Nothofagus dombeyi, Schinus patagonicus, and Weinmannia trichosperma, and macrophytes Hydrocotyle chamaemorus, Isöetes chubutiana, Galium sp., Myriophyllum quitense, Nitella sp. (algae), Potamogeton linguatus, Ranunculus sp., and Schoenoplectus californicus. Fresh leaves were analyzed as well as leaves decomposing within the aquatic bodies, collected from lakes Futalaufquen and Rivadavia (Los Alerces National Park), and lakes Moreno and Nahuel Huapi (Nahuel Huapi National Park). The elements studied were heavy metals Ag, As, Cd, Hg, and U, major elements Ca, K, and Fe, and trace elements Ba, Br, Co, Cr, Cs, Hf, Na, Rb, Se, Sr, and Zn. Geochemical tracers La and Sm were also determined to evaluate contamination of the biological tissues by geological particulate (sediment, soil, dust) and to implement concentration corrections.

  11. Pseudotsuga menziesii invasion in native forests of Patagonia, Argentina: What about mycorrhizas?

    NASA Astrophysics Data System (ADS)

    Salgado Salomón, María Eugenia; Barroetaveña, Carolina; Rajchenberg, Mario

    2013-05-01

    Pseudotsuga menziesii is one of the most widely planted conifers in the Patagonian Andes of Argentina, with invading characteristics that are widely reported. Nevertheless, little is known about the role of its obligate mycorrhizal associations in limiting or fostering the establishment of invading seedlings. We studied the richness and abundance of endo- (AM) and ectomycorrhizae (EM) present in P. menziesii seedlings growing in six Nothofagus forests invaded by P. menziesii seedlings (Nothofagus + P. menziesii) matrices. One transect along the maximum effective recruitment distance (ERA) was established at each site in order to wrench seedlings and sample soils. P. menziesii showed effective associations with a wide range of mycorrhizal symbionts: AM (ranging between 13.21 and 37.11%), EM (ranging between 79.91 and 89.14%) and Dark Septate Endophytes (DSE). Seedlings' mycorrhization percentages were always high, suggesting a good nursery effect provided by neighboring plantations. Mycorrhizal abundance (AM% and EM%), EM morphotypes richness and evenness showed significant differences between sites, indicating that P. menziesii displays a high plasticity being capable to select the more convenient mycorrhizal arrangement at each invaded site.

  12. Postglacial history of the Patagonian forest/steppe ecotone (41-43°S)

    NASA Astrophysics Data System (ADS)

    Iglesias, Virginia; Whitlock, Cathy; Markgraf, Vera; Bianchi, María Martha

    2014-06-01

    Patagonian vegetation has dramatically changed in composition and distribution over the last 23,000 years. Although the vegetation history has been inferred from individual pollen records, the regional patterns and drivers of vegetation development are poorly understood. High resolution pollen and charcoal data from eleven sites located along the eastern flanks of the Patagonian Andes (41-43°S) were examined to reconstruct the Lateglacial and Holocene vegetation and fire history of steppe/forest ecotone and separate the relative influence of climatic versus non-climatic factors in shaping the patterns of ecological change. Pollen data indicate that, as the Lateglacial climate became progressively wetter, the initial steppe vegetation was replaced by open forest of Nothofagus in the Lateglacial and early Holocene periods, and by closed forest in the late Holocene. Fire activity was lowest during the Lateglacial/early-Holocene transition and gradually increased through the Holocene. Prior to ca 5000 cal yr BP, the conifer Austrocedrus chilensis possibly persisted in isolated populations along the eastern boundary of its modern distribution. Cooler/more humid conditions after ca 5000 cal yr BP allowed the development of the modern mixed Nothofagus-Austrocedrus forest. The paleoenvironmental record points to the sensitivity of the forest/steppe ecotone in the past, not only to climate but also to complex environmental feedbacks that amplified the effects of climate change.

  13. Postglacial formation and dynamics of North Patagonian Rainforest in the Chonos Archipelago, Southern Chile

    NASA Astrophysics Data System (ADS)

    Haberle, S. G.; Bennett, K. D.

    2004-12-01

    Pollen analysis of continuous sediment cores from two lakes in the northern Chonos Archipelago (44°S) in southern Chile shows a complete postglacial record of vegetation change. The fossil records indicate that deglaciation was complete in the northern Chonos by at least 13,600 14C yr BP. Ericaceous heath and grassland persisted for more than 600 years after deglaciation under the influence of dry/cold climates and frequent burning. Nothofagus- Pilgerodendron- Podocarpus forest, with modern analogues in the southern Chonos Archipelago, was established across the northern islands by 12,400 14C yr BP under increasingly warm and wet climates. There is no evidence for a return to cooler climates during the Younger Dryas chronozone. The rise of Tepualia stipularis and Weinmannia trichosperma as important forest components between 10,600 and 6000 14C yr BP may be associated with climates that were warmer than present. The collapse of Pilgerodendron communities during this time may have been triggered by a combination of factors related to disturbance frequency including tephra deposition events, fire and climate change. After 6000 14C yr BP Pilgerodendron recovers and Nothofagus-Pilgerodendron-Tepualia forest persists until the present. European logging and burning activity may have increased the susceptibility of North Patagonian Rainforest to invasion by introduced species and to future collapse of the long-lived Pilgerodendron communities.

  14. Hydro-Geomorphologic Effects Of Large Wood Jams On A Third-Order Stream (Tierra Del Fuego, Argentina)

    NASA Astrophysics Data System (ADS)

    Mao, L.; Andreoli, A.; Comiti, F.; Lenzi, M. A.; Iturraspe, R.; Burns, S.; Novillo, M. G.

    2007-05-01

    Dead wood pieces, especially when organized in jams, play an important geomorphic role in streams because of the effects on flow hydraulics, pool formation and sediments storage. The increase of stream morphological diversity and complexity also exerts also an important ecological role. This work reports on geomorphic role of large wood pieces and jams in a third order mountain stream located in the Southern Tierra del Fuego (Argentina), and draining an old-growth nothofagus forested basin not influenced by the beavers damming activity. Even if the in-stream number of wood pieces (length > 1m; diameter > 0.1 m) is comparable to what observed in other climatic areas, the slow growth of the nothofagus forest causes a lower wood abundance in terms of volumetric load. Since the relatively small dimensions of the surveyed large wood pieces, almost the 70% of them demonstrated to have been fluvial transported and the also wood jams reflect the apparent dynamic of wood in the channel. Wood jams exert a significant influence on the channel morphology, representing almost the half of the drop caused by steps and being responsible for the creation of 30% of the pools. The LW-forced pool volume is strongly and positively correlated to the height of the LW jam, and a significant inverse relationship between pool spacing and wood density within is evident if only the LW-forced pools are considered. The geomorphic influence of LW jams is also exerted by a considerable sediment storing capacity.

  15. Glacier fluctuations during the last 400 years at Mount San Lorenzo and Santa Ines Island, southern Chile

    NASA Astrophysics Data System (ADS)

    Aravena, J.; Luckman, B. H.

    2007-12-01

    We examine the local glacier fluctuations for the last 400 years in two mountain areas of the western coast of southernmost South America, Mount San Lorenzo and Santa Ines Island, using dendroglaciologic, geomorphologic and historical evidence. Mount San Lorenzo moraines span between 1636 and 1927 with periods of more frequent occurrence of glacial advances for the years 1670, 1770, 1870 and 1910. Santa Ines glacial advances are less numerous than in Mount San Lorenzo with well defined, clearly separated frontal moraines. The moraines were colonized by Nothofagus betuloides and Nothofagus antarctica two species with clear and well-preserved tree rings and the total age of the sampled trees was more precisely estimated. Dated moraines cover the last 300 years with evidence for advances during late 1600s, around 1800, 1860, 1910, 1930 and 1960. Further work is needed in dendroglaciological dating, geomorphologic surveying, and better understanding of local glacial dynamics for several glaciers to obtain a regional history of the glacier fluctuations of the southern Andes.

  16. Derechos Educacionales de los Padres: Una Explicacion de los Procedimientos de Seguridad para los Padres de Ninos con Discapacidades. Bajo la Clausula del Acta de Educacion para Individuos con Discapacidades (IDEA) y las Reglas para la Administracion del Acta de Educacion para Ninos Excepcionales (Educational Rights of Parents: An Explanation of Procedural Safeguards Available to Parents of Children with Disabilities. Under Provisions of the Individuals with Disabilities Education Act (IDEA) and the Rules for the Administration of the Exceptional Children's Educational Act [ECEA]).

    ERIC Educational Resources Information Center

    Mountain Plains Regional Resource Center, Des Moines, IA.

    This pamphlet, in Spanish, describes Colorado parents' educational rights under federal and state special education rules and regulations. It addresses: (1) free appropriate public education and termination of services; (2) required prior notice to parents if there is a proposed change or refusal to change a child's special education program; (3)…

  17. 78 FR 65972 - Caribbean Fishery Management Council; Scoping Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-04

    ..., Bajo de Sico, and Tourmaline Bank. The goal of modifying the closures is to protect the red hind... Closed Areas off Puerto Rico: Abrir La Sierra Bank, Bajo de Sico, and Tourmaline Bank,'' considers the... Abrir La Sierra to 12 months. Action 2: Modify the length of the closed season for Tourmaline Bank...

  18. Indirect effects of prey swamping: differential seed predation during a bamboo masting event.

    PubMed

    Kitzberger, Thomas; Chaneton, Enrique J; Caccia, Fernando

    2007-10-01

    Resource pulses often involve extraordinary increases in prey availability that "swamp" consumers and reverberate through indirect interactions affecting other community members. We developed a model that predicts predator-mediated indirect effects induced by an epidemic prey on co-occurring prey types differing in relative profitability/preference and validated our model by examining current-season and delayed effects of a bamboo mass seeding event on seed survival of canopy tree species in mixed Patagonian forests. The model shows that predator foraging behavior, prey profitability, and the scale of prey swamping influence the character and strength of short-term indirect effects on various alternative prey. When in large prey-swamped patches, nonselective predators decrease predation on all prey types. Selective predators, instead, only benefit prey of similar quality to the swamping species, while very low or high preference prey remain unaffected. Negative indirect effects (apparent competition) may override such positive effects (apparent mutualism), especially for highly preferred prey, when prey-swamped patches are small enough to allow predator aggregation and/or predators show a reproductive numerical response to elevated food supply. Seed predation patterns during bamboo (Chusquea culeou) masting were consistent with predicted short-term indirect effects mediated by a selective predator foraging in large prey-swamped patches. Bamboo seeds and similarly-sized Austrocedrus chilensis (ciprés) and Nothofagus obliqua (roble) seeds suffered lower predation in bamboo flowered than nonflowered patches. Predation rates on the small-seeded Nothofagus dombeyi (coihue) and the large-seeded Nothofagus alpina (rauli) were independent of bamboo flowering. Indirect positive effects were transient; three months after bamboo seeding, granivores preyed heavily upon all seed types, irrespective of patch flowering condition. Moreover, one year after bamboo seeding

  19. Influence of native forest cover on water yield in southern Chile: a comparative study of small watersheeds

    NASA Astrophysics Data System (ADS)

    Alvarez-Garretón, Camila; McPhee, James; Little, Christian; Lara, Antonio

    2010-05-01

    In this work we compare water yield in five small watersheds (surface area from 7 to 70 hectares) with different native forest cover, located in Southern Chile (39.5° Lat S). Forest covers include unmanaged second-growth forest of deciduous Nothofagus obliqua - Nothofagus nervosa ("Rsm", 7,4 ha), thinned second-growth forest of deciduous N. obliqua - N. nervosa with 35% of basal area extraction ("Rcm", 12,6 ha), altered evergreen old-growth forest dominated by Laurelia philippiana ("Tran", 7,5 ha), pristine old-growth forest of Nothofagus dombeyi ("Enc", 72,1 ha) and grassland as a control ("Prad", 12,3 ha). It is expected that differences in water yield are related mainly to differences in native forest structure, given that all watersheds have similar geomorphology and are located close to each other. We monitored daily streamflow and precipitation during four hydrological years (April 2003 through Dec 2006). Data were collected on each watershed and analyzed, first by recession curve classification, then by separating base flow and direct runoff. Subsequently, storm events were individualized, in order to isolate the effect of different antecedent soil moisture conditions. Variations in hydrograph recession curves as well as rainfall-runoff coefficients are analyzed in relation to differences in land cover type, storm magnitude and duration, antecedent soil moisture and presence of leafs. In agreement with the literature, all forested watersheds consume more water than a grassland watershed, but display a slower release of soil water storage. On the other hand, results show that managed forest basins yield more total, direct and base runoff in comparison to unmanaged watersheds. Further, unmanaged natural forests display flatter recession curves, implying a longer duration of base flow after storm events. This behavior has important implications for valuation and management of water yield, as an Ecosystem Service of native forest in Chile; it suggests that it

  20. An evaluation of the impacts of energy tree plantations on water resources in the United Kingdom under present and future UKCIP02 climate scenarios

    NASA Astrophysics Data System (ADS)

    Calder, Ian R.; Nisbet, Tom; Harrison, Jennifer A.

    2009-07-01

    The Hydrological Land Use Change model was used to assess the range of water resource impacts associated with four potential energy tree species (Eucalyptus nitens, Eucalyptus gunnii, Nothofagus sp., and Fraxinus excelsior) at eight United Kingdom locations under present and future, Environment Agency Rainfall and Weather Impacts Generator, climate scenarios generated using UK Climate Impacts Programme 2002 (UKCIP02). Parameter values were derived using expert opinion and interpolation because of limited data. For Fraxinus excelsior, there are questions concerning the unusual, in a world context, published findings that evaporation from a tree crop is less than that from grass. Model predictions indicated that under the present climate all tree species, excepting Fraxinus excelsior, at all sites have greater mean annual evaporation, (8 to 84%) and reduced water yields (-6 to -97%) compared with grass. The predicted increase in tree evaporation arises from parameter values reflecting both increased rainfall interception and higher transpiration due to deeper rooting depths. Under future climate scenarios, (1) "potential annual yield" (difference between actual rainfall and potential evaporation) will decrease, becoming negative at all studied sites in England and Wales by 2080; (2) at drier sites and for species with highest evaporation rates, E. nitens and Nothofagus, evaporation rates will decrease; (3) at wetter sites and for all species, evaporation rates will increase; (4) at all sites and for all species, water yields will decrease; (5) differences between species remain the same, with evaporation rates increasing and water yield decreasing in the order Fraxinus excelsior, grass, E. gunnii, Nothofagus, and E. Nitens; and (6) there is an overall trend through time toward convergence in water yields from trees and grass. If higher water yield predictions for Fraxinus excelsior are proved correct, this would represent an attractive land use option for water and

  1. Nop9 is an RNA binding protein present in pre-40S ribosomes and required for 18S rRNA synthesis in yeast

    PubMed Central

    Thomson, Emma; Rappsilber, Juri; Tollervey, David

    2007-01-01

    Proteomic analyses in yeast have identified a large number of proteins that are associated with preribosomal particles. However, the product of the yeast ORF YJL010C, herein designated as Nop9, failed to be identified in any previous physical or genetic analysis of preribosomes. Here we report that Nop9 is a nucleolar protein, which is associated with 90S and 40S preribosomes. In cells depleted of Nop9p, early cleavages of the 35S pre-rRNA are inhibited, resulting in the nucleolar retention of accumulated precursors and a failure to synthesize 18S rRNA. Nop9 contains multiple pumilio-like putative RNA binding repeats and displays robust in vitro RNA binding activity. The identification of Nop9p as a novel, essential factor in the nuclear maturation of 90S and pre-40S ribosomal subunits shows that the complement of ribosome synthesis factors remains incomplete. PMID:17956976

  2. Alx3 regulates the spatial differences in hair pigment underlying stripe patterns in rodents

    PubMed Central

    Mallarino, Ricardo; Henegar, Corneliu; Mirasierra, Mercedes; Manceau, Marie; Shradin, Carsten; Vallejo, Mario; Beronja, Slobodan; Barsh, Gregory S.; Hoekstra, Hopi E.

    2017-01-01

    Mammalian color patterns are among the most recognizable characters found in nature and can have a profound impact on fitness. However, little is known about the mechanisms underlying their formation and subsequent evolution. Here we show that, in the African striped mouse (Rhabdomys pumilio), periodic dorsal stripes result from underlying differences in melanocyte maturation, which give rise to spatial variation in hair color, and we identify the transcription factor Alx3 as a regulator of this process. In embryonic dorsal skin, patterned expression of Alx3 foreshadows pigment stripes, and acts to directly repress Mitf, a master regulator of melanocyte differentiation, giving rise to light-colored hair. Moreover, Alx3 is also upregulated in the light stripes of chipmunks, which have independently evolved a similar pattern of dorsal stripes. Our results reveal a previously unappreciated mechanism for modulating spatial variation in hair color, and provide new insight into the ways in which phenotypic novelty evolves. PMID:27806375

  3. Translation and silencing in RNA granules: a tale of sand grains

    PubMed Central

    Pimentel, Jerónimo; Boccaccio, Graciela L.

    2014-01-01

    The transcriptome at the synapse consists of thousands of messengers encoding several cellular functions, including a significant number of receptors and ion channels and associated proteins. The concerted translational regulation of all these molecules contributes to the dynamic control of synaptic strength. Cumulative evidence supports that dendritic RNA granules and mRNA-silencing foci play an important role in translational regulation. Several relevant RBPs – FMRP; FUS/TLS; TDP-43; Staufen; Smaug; Pumilio; CPEB; HuD; ZBP1; and DDX6 among others – form granules that contain dormant mRNAs repressed by multiple pathways. Recent reports indicate that dendritic granules may contain stalled polysomes, and furthermore, active translation may occur in association with RNA granules. Here, we discuss the molecules and pathways involved in this continuum of RNA granules that contain masked mRNAs, mRNAs trapped in inactive polysomes or mRNAs engaged in translation. PMID:25100944

  4. Poor alkaloid sequestration by arrow poison frogs of the genus Phyllobates from Costa Rica.

    PubMed

    Mebs, Dietrich; Alvarez, Joseph Vargas; Pogoda, Werner; Toennes, Stefan W; Köhler, Gunther

    2014-03-01

    Frogs of the genus Phyllobates from Colombia are known to contain the highly toxic alkaloid batrachotoxin, but species from Central America exhibit only very low levels or are entirely free of this toxin. In the present study alcohol extracts from 101 specimens of Phyllobates lugubris and Phyllobates vittatus and 21 of three sympatric species (Dendrobates pumilio, Dendrobates auratus, Dendrobates granuliferus) from Costa Rica were analyzed by gas chromatography-mass spectrometry. Whereas the extracts of the Dendrobates species exhibited typical profiles of toxic alkaloids, those of the two Phyllobates species contained low levels of few alkaloids only, batrachotoxin was not detected. Although the feeding pattern of the Dendrobates and Phyllobates species are similar as revealed by examination of their stomach content (mainly ants and mites), the Phyllobates species are poorly sequestering alkaloids from their food source in contrast to the Dendrobates frogs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Structure and Function of Nematode RNA-Binding Proteins

    PubMed Central

    Kaymak, Ebru; Wee, L.M.; Ryder, Sean P.

    2010-01-01

    RNA-binding proteins are critical effectors of gene expression. They guide mRNA localization, translation, and stability, and potentially play a role in regulating mRNA synthesis. The structural basis for RNA recognition by RNA-binding proteins is the key to understanding how they target specific transcripts for regulation. Compared to other metazoans, nematode genomes contain a significant expansion in several RNA-binding protein families, including Pumilio-FBF (PUF), TTP-like zinc finger (TZF), and argonaute-like (AGO) proteins. Genetic data suggest that individual members of each family have distinct functions, presumably due to sequence variations that alter RNA binding specificity or protein interaction partners. In this review, we highlight example structures and identify the variable regions that likely contribute to functional divergence in nematodes. PMID:20418095

  6. Morpho-histological studies in the aromatic species of Chenopodium from Argentina.

    PubMed

    Bonzani, N E; Barboza, G E; Bugatti, M A; Ariza Espinar, L

    2003-04-01

    A morpho-histological study of the vegetative organs (stem and leaf) of the aromatic species of Chenopodium L. from Argentina [C. ambrosioides L., C. burkartii (Aellen) Vorosch., C. carinatum R. Br., C. chilense Schrad., C. graveolens Willd. var. bangii (Murr) Aellen, C. haumanii Ulbr., C. multifidum L., C. oblanceolatum (Speg.) Giusti, C. pumilio R. Br., C. retusum (Moq.) Moq., and C. venturii (Aellen) Cabrera] was carried out. Classifications for the glandular and non-glandular trichomes are established and their presence among species is presented. A variant in both the dorsiventral and isobilateral mesophyll is reported; some data are valuable for systematic purposes and for the identification of dried and smashed material used as vegetal drug.

  7. Translation and silencing in RNA granules: a tale of sand grains.

    PubMed

    Pimentel, Jerónimo; Boccaccio, Graciela L

    2014-01-01

    The transcriptome at the synapse consists of thousands of messengers encoding several cellular functions, including a significant number of receptors and ion channels and associated proteins. The concerted translational regulation of all these molecules contributes to the dynamic control of synaptic strength. Cumulative evidence supports that dendritic RNA granules and mRNA-silencing foci play an important role in translational regulation. Several relevant RBPs - FMRP; FUS/TLS; TDP-43; Staufen; Smaug; Pumilio; CPEB; HuD; ZBP1; and DDX6 among others - form granules that contain dormant mRNAs repressed by multiple pathways. Recent reports indicate that dendritic granules may contain stalled polysomes, and furthermore, active translation may occur in association with RNA granules. Here, we discuss the molecules and pathways involved in this continuum of RNA granules that contain masked mRNAs, mRNAs trapped in inactive polysomes or mRNAs engaged in translation.

  8. Small mammals as hosts of immature ixodid ticks.

    PubMed

    Horak, I G; Fourie, L J; Braack, L E O

    2005-09-01

    Two hundred and twenty-five small mammals belonging to 16 species were examined for ticks in Free State, Mpumalanga and Limpopo Provinces, South Africa, and 18 ixodid tick species, of which two could only be identified to genus level, were recovered. Scrub hares, Lepus saxatilis, and Cape hares, Lepus capensis, harboured the largest number of tick species. In Free State Province Namaqua rock mice, Aethomys namaquensis, and four-striped grass mice, Rhabdomys pumilio, were good hosts of the immature stages of Haemaphysalis leachi and Rhipicephalus gertrudae, while in Mpumalanga and Limpopo Provinces red veld rats, Aethomys chrysophilus, Namaqua rock mice and Natal multimammate mice, Mastomys natalensis were good hosts of H. leachi and Rhipicephalus simus. Haemaphysalis leachi was the only tick recovered from animals in all three provinces.

  9. Studies on Rift Valley fever in some African murids (Rodentia: Muridae).

    PubMed Central

    Swanepoel, R.; Blackburn, N. K.; Efstratiou, S.; Condy, J. B.

    1978-01-01

    Brains, spleens and livers of 2214 murids, 27 shrews and 7 dormice, trapped at 7 sites in Rhodesia, were tested in 277 pools for the presence of Rift Valley Fever virus. There were no isolations of Rift Valley Fever, but 69 isolations of an unidentified virus were obtained. Sixteen out of 867 sera had low-titre haemagglutination-inhibition activity against Rift Valley Fever antigen, but only one out of 1260 sera had neutralizing antibody. The evidence suggests that murids fail to encounter infection in nature and are unlikely to play a role in circulation and dissemination of Rift Valley Fever virus. Four out of seven widely distributed species of muried, Rhabdomys pumilio, Saccostomys campestris, Aethomys chrysophilus and Lemniscomys griselda, were shown to be capable of circulating amounts of virus likely to be infective for mosquitoes. PMID:632561

  10. Studies on Rift Valley fever in some African murids (Rodentia: Muridae).

    PubMed

    Swanepoel, R; Blackburn, N K; Efstratiou, S; Condy, J B

    1978-04-01

    Brains, spleens and livers of 2214 murids, 27 shrews and 7 dormice, trapped at 7 sites in Rhodesia, were tested in 277 pools for the presence of Rift Valley Fever virus. There were no isolations of Rift Valley Fever, but 69 isolations of an unidentified virus were obtained. Sixteen out of 867 sera had low-titre haemagglutination-inhibition activity against Rift Valley Fever antigen, but only one out of 1260 sera had neutralizing antibody. The evidence suggests that murids fail to encounter infection in nature and are unlikely to play a role in circulation and dissemination of Rift Valley Fever virus. Four out of seven widely distributed species of muried, Rhabdomys pumilio, Saccostomys campestris, Aethomys chrysophilus and Lemniscomys griselda, were shown to be capable of circulating amounts of virus likely to be infective for mosquitoes.

  11. An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species

    PubMed Central

    Dreher, Corinna E.; Cummings, Molly E.; Pröhl, Heike

    2015-01-01

    Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake) and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast) of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and other ecological

  12. Toward a General Approach for RNA-Templated Hierarchical Assembly of Split-Proteins

    PubMed Central

    Furman, Jennifer L.; Badran, Ahmed H.; Ajulo, Oluyomi; Porter, Jason R.; Stains, Cliff I.; Segal, David J.; Ghosh, Indraneel

    2010-01-01

    The ability to conditionally turn on a signal or induce a function in the presence of a user-defined RNA target has potential applications in medicine and synthetic biology. Although sequence-specific pumilio repeat proteins can target a limited set of ssRNA sequences, there are no general methods for targeting ssRNA with designed proteins. As a first step toward RNA recognition, we utilized the RNA binding domain of argonaute, implicated in RNA interference, for specifically targeting generic 2-nucleotide, 3' overhangs of any dsRNA. We tested the reassembly of a split-luciferase enzyme guided by argonaute-mediated recognition of newly generated nucleotide overhangs when ssRNA is targeted by a designed complementary guide sequence. This approach was successful when argonaute was utilized in conjunction with a pumilio repeat and expanded the scope of potential ssRNA targets. However, targeting any desired ssRNA remained elusive as two argonaute domains provided minimal reassembled split-luciferase. We next designed and tested a second hierarchical assembly, wherein ssDNA guides are appended to DNA hairpins that serve as a scaffold for high affinity zinc fingers attached to split-luciferase. In the presence of a ssRNA target containing adjacent sequences complementary to the guides, the hairpins are brought into proximity, allowing for zinc finger binding and concomitant reassembly of the fragmented luciferase. The scope of this new approach was validated by specifically targeting RNA encoding VEGF, hDM2, and HER2. These approaches provide potentially general design paradigms for the conditional reassembly of fragmented proteins in the presence of any desired ssRNA target. PMID:20681585

  13. Description of Laccomimus gen. n. and eleven new species from the Neotropical region (Coleoptera, Dytiscidae, Laccophilinae).

    PubMed

    Toledo, Mario; Michat, Mariano C

    2015-07-27

    A new genus of laccophiline diving beetles, Laccomimus gen. n., is here described on the basis of a large number of specimens from various collections formerly misidentified as members of the Neotropical genus Laccodytes Régimbart, 1895. Except for similar size, however, the new genus is not closely related to Laccodytes. Instead, it seems to be sister to the Oriental genus Laccosternus Brancucci, 1983, both sharing a similar body size and shape, characters of the female genital structures, and shape of the prosternal process. Twelve species are recognised within Laccomimus, all new to science except Laccomimus pumilio (LeConte, 1878) comb. n., the type species. The new species are: Laccomimus alvarengi sp. n., L. amazonas sp. n., L. bolivari sp. n., L. bordoni sp. n., L. distinctus sp. n., L. improvidus sp. n., L. malkini sp. n., L. spangleri sp. n., L. spinosus sp. n., L. variegatus sp. n., L. youngi sp. n. The distribution of the new genus includes most of the Neotropics, with one species, L. pumilio, reaching Florida, USA. Each taxon is described and illustrated and a key for their identification is provided. Laccomimus is a widespread and relatively common genus in tropical America, the species of which have a wide distributional range, except for a few confined to more restricted areas. In spite of this, Laccomimus is a very uniform genus in body shape, size and colouration, and in most cases identification of the species is possible only after examination of the male genitalia. A key to distinguish genera of the tribe Laccophilini is also presented.

  14. An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species.

    PubMed

    Dreher, Corinna E; Cummings, Molly E; Pröhl, Heike

    2015-01-01

    Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake) and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast) of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and other ecological

  15. Life history strategy influences parasite responses to habitat fragmentation.

    PubMed

    Froeschke, Götz; van der Mescht, Luther; McGeoch, Melodie; Matthee, Sonja

    2013-12-01

    Anthropogenic habitat use is a major threat to biodiversity and is known to increase the abundance of generalist host species such as rodents, which are regarded as potential disease carriers. Parasites have an intimate relationship with their host and the surrounding environment and it is expected that habitat fragmentation will affect parasite infestation levels. We investigated the effect of habitat fragmentation on the ecto- and endoparasitic burdens of a broad niche small mammal, Rhabdomys pumilio, in the Western Cape Province, South Africa. Our aim was to look at the effects of fragmentation on different parasite species with diverse life history characteristics and to determine whether general patterns can be found. Sampling took place within pristine lowland (Fynbos/Renosterveld) areas and at fragmented sites surrounded and isolated by agricultural activities. All arthropod ectoparasites and available gastrointestinal endoparasites were identified. We used conditional autoregressive models to investigate the effects of habitat fragmentation on parasite species richness and abundance of all recovered parasites. Host density and body size were larger in the fragments. Combined ecto- as well as combined endoparasite taxa showed higher parasite species richness in fragmented sites. Parasite abundance was generally higher in the case of R. pumilio individuals in fragmented habitats but it appears that parasites that are more permanently associated with the host's body and those that are host-specific show the opposite trend. Parasite life history is an important factor that needs to be considered when predicting the effects of habitat fragmentation on parasite and pathogen transmission. Copyright © 2013 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  16. A new species of Alsodes (Anura: Alsodidae) from Altos de Cantillana, central Chile.

    PubMed

    Charrier, Andrés; Correa, Claudio; Castro, Camila; Méndez, Marco A

    2015-02-05

    Based on morphological and molecular evidence (mitochondrial and nuclear sequences) we describe a new species of spiny-chest frog, Alsodes cantillanensis, from central Chile (around 34°S). The type locality, Quebrada Infiernillo, is located in the Coastal Range at approximately 65 km from Santiago (Metropolitan Region), the capital of Chile. The distribution of the new species is included entirely in that of A. nodosus (32-36°S approximately), which was identified as the sister taxon according to molecular phylogenetic analyses. Moreover, both species are sympatric in the type locality. The new species was found in a Nothofagus macrocarpa relict forest potentially threatened by gold mining activities. We identify other threats for its conservation and some biological data needed for understanding the evolution of this species. This discovery reveals the scarce knowledge about biogeography, evolution and ecology of spiny-chest frogs from central Chile. 

  17. A new species of Rhytidognathus (Carabidae, Migadopini) from Argentina

    PubMed Central

    Roig-Juñent, Sergio; Rouaux, Julia

    2012-01-01

    Abstract The Migadopini are a small tribe of Carabidae with 47 species that occur in South America, Australia, and New Zealand, in the sub-Antarctic areas. In South America, most of the genera inhabit areas related to sub-Antartic Nothofagus forest except two monogeneric genera, the Ecuadorian genus Aquilex Moret and the Pampean genus Rhytidognathus Chaudoir. These two genera are geographically isolated from the remaining five South American genera. New material of Rhytidognathus from the northeast of Buenos Aires province and from Entre Ríos province permits establishing that the previous records of Rhytidognathus ovalis (Dejean) for Argentina were erroneous and that it belongs to a new species. Based on external morphological characters and from male and female genitalia we describe Rhytidognathus platensis as a new species. In this contribution we provide illustrations, keys, habitat characteristics and some biogeographic considerations on the distribution of Rhytidognathus. PMID:23275755

  18. Ecological responses to mid- and late-Holocene climate variability in the Patagonian Andes (lat 34-55S)

    NASA Astrophysics Data System (ADS)

    Iglesias, V.; Whitlock, C. L.; Bianchi, M. M.; Markgraf, V.; Navarro, D.; Bartlein, P. J.

    2009-12-01

    Along the eastern Andes, a prominent ecotone separates steppe from North Patagonian forest, dominated by Nothofagus spp. and at middle latitudes by Nothofagus spp. and Austrocedrus. The elevational position of the ecotone is determined by effective moisture, which in turn is governed by the strength and latitudinal position of the Southern Westerlies. As a result, past changes in forest composition and fire activity provide an opportunity to examine past climate variations in this region. The vegetation and fire history can be inferred from a longitudinal transect of 8 lake and bog sites. Pollen data indicate that, on millennial time scales, late-glacial steppe was replaced by open forest in the early Holocene and then by closed forest in the middle and late Holocene (south of lat 36S). Charcoal data suggest that fire activity south of latitude 41S was highest between 11 and 8-6 ka and significantly decreased between 8-6 and 3 ka. The opposite pattern occurred north of lat 41S, where fire activity was highest between 6 and 3 ka. Between lat 40 and 43S, fires were nearly as frequent between 3 and 1 ka as in the early Holocene, and this period was followed by a decline in fire activity to the 20th century. The long-term vegetation and fire patterns are partly explained as a response to variations in seasonal and annual insolation and their effect on summer (fire-season) conditions. In the last 5000 years, changes in precipitation and interannual/decadal variability, inferred from independent data, matched closely with variations in the abundance of Nothofagus, Austrocedrus, and Poaceae pollen and charcoal influx. Four climate scenarios (dry conditions/low variability, dry conditions/high variability, wet conditions/high variability, wet conditions/low variability) registered distinctive ecotonal responses. For example, wet conditions led to the expansion of forest into steppe, and high moisture variability, mainly through its effects on fire occurrence, shaped the

  19. First Evidence for Wollemi Pine-type Pollen (Dilwynites: Araucariaceae) in South America

    PubMed Central

    Macphail, Mike; Carpenter, Raymond J.; Iglesias, Ari; Wilf, Peter

    2013-01-01

    We report the first fossil pollen from South America of the lineage that includes the recently discovered, extremely rare Australian Wollemi Pine, Wollemia nobilis (Araucariaceae). The grains are from the late Paleocene to early middle Eocene Ligorio Márquez Formation of Santa Cruz, Patagonia, Argentina, and are assigned to Dilwynites, the fossil pollen type that closely resembles the pollen of modern Wollemia and some species of its Australasian sister genus, Agathis. Dilwynites was formerly known only from Australia, New Zealand, and East Antarctica. The Patagonian Dilwynites occurs with several taxa of Podocarpaceae and a diverse range of cryptogams and angiosperms, but not Nothofagus. The fossils greatly extend the known geographic range of Dilwynites and provide important new evidence for the Antarctic region as an early Paleogene portal for biotic interchange between Australasia and South America. PMID:23894439

  20. Coevolution and the adaptive value of autumn tree colours: colour preference and growth rates of a southern beech aphid.

    PubMed

    Ramírez, C C; Lavandero, B; Archetti, M

    2008-01-01

    The evolutionary explanation for the change in leaf colour during autumn is still debated. Autumn colours could be a signal of defensive commitment towards insects (coevolution) or an adaptation against physical damage because of light at low temperatures (photoprotection). These two hypotheses have different predictions: (1) under the coevolution hypothesis, insects should not prefer red leaves in autumn and grow better in spring on trees with green autumn leaves; and (2) under the photoprotection hypothesis, insects should prefer and grow better on trees with red leaves because they provide better nutrition. Studying colour preference in autumn and growth rates in spring of a southern beech aphid species (Neuquenaphis staryi) on Nothofagus alessandrii, we found preference for green leaves in autumn but no differential performance of aphids in spring. We suggest that aphid preference for green might have evolved to exploit better their host during the autumn rather than to improve their performance in spring.

  1. Philodryas chamissonis (Reptilia: Squamata: Colubridae) preys on the arboreal marsupial Dromiciops gliroides (Mammalia: Microbiotheria: Microbiotheriidae).

    PubMed

    Muñoz-Leal, S; Ardiles, K; Figueroa, R A; González-Acuña, D

    2013-02-01

    Philodryas chamissonis, the Chilean long-tailed snake, is a diurnal predator mainly of Liolaemus lizards, but also of amphibians, birds, rodents and juvenile rabbits. Dromiciops gliroides (Colocolo opossum) is an arboreal marsupial endemic of temperate rainforest of southern South America. Little information is available about this marsupial's biology and ecology. Here we report the predation of one Colocolo opossum by an adult female P. chamissonis in a mixed Nothofagus forest, composed mainly by N. dombeyi, N. glauca and N. alpina trees, in the "Huemules de Niblinto" National Reserve, Nevados de Chillán, Chile. Since these two species have different activity and habitat use patterns, we discuss how this encounter may have occurred. Although it could just have been an opportunistic event, this finding provides insights into the different components of food chains in forest ecosystems of Chile.

  2. A new species of Rhytidognathus (Carabidae, Migadopini) from Argentina.

    PubMed

    Roig-Juñent, Sergio; Rouaux, Julia

    2012-01-01

    The Migadopini are a small tribe of Carabidae with 47 species that occur in South America, Australia, and New Zealand, in the sub-Antarctic areas. In South America, most of the genera inhabit areas related to sub-Antartic Nothofagus forest except two monogeneric genera, the Ecuadorian genus Aquilex Moret and the Pampean genus Rhytidognathus Chaudoir. These two genera are geographically isolated from the remaining five South American genera. New material of Rhytidognathus from the northeast of Buenos Aires province and from Entre Ríos province permits establishing that the previous records of Rhytidognathus ovalis (Dejean) for Argentina were erroneous and that it belongs to a new species. Based on external morphological characters and from male and female genitalia we describe Rhytidognathus platensis as a new species. In this contribution we provide illustrations, keys, habitat characteristics and some biogeographic considerations on the distribution of Rhytidognathus.

  3. Deglacial and postglacial vegetation changes on the eastern slopes of the central Patagonian Andes (47°S)

    NASA Astrophysics Data System (ADS)

    Villa-Martínez, Rodrigo; Moreno, Patricio I.; Valenzuela, Marcela A.

    2012-01-01

    We report pollen, spore, and charcoal records from Lago Augusta (47°05'S, 72°23'W, 440 m a.s.l.), a small closed-basin lake located near the modern forest-steppe ecotone east of the Andes in Central Patagonia, Chile. The record shows local ice-free conditions through the last glacial termination in the Río Chacabuco Valley and flooding by an ice-dammed lake. Once this proglacial lake ceased to inundate areas above 450 m a.s.l., the valley was colonized by herbs, shrubs and evergreen rainforest taxa between 15,600 and 16,000 cal yr BP, indicating an open landscape under cold/wet conditions. Millennial-scale fluctuations in the hygrophilous conifer Fitzroya/ Pilgerodendron suggest precipitation variations within a cool/wet climate between 11,800 and 13,400 cal yr BP, followed by the establishment of dense Nothofagus forests between 9800 and 11,800 cal yr BP and declines in hygrophilous and cold-resistant trees, herbs and shrubs. This interval coincided with peak fire activity and laminated carbonate deposition. Nothofagus forests have persisted with little variation since 9800 cal yr BP, except for a sudden decline associated with a rapid increase in Rumex cf. acetosella, an exotic weed introduced by Europeans. Our results and interpretations are best explained by changes in the strength/position of the southern westerly winds at millennial and multi-millennial timescales since the last glaciation. Contrary to previous interpretations, we propose increased precipitation of westerly origin in the Andean sector of central-east Patagonia between 11,800 and 16,000 cal yr BP followed by a decline between 9800 and 11,800 cal yr BP and an increase thereafter. These trends are coherent with variations of the southern westerly winds identified in other terrestrial mid-latitude records, suggesting zonally symmetric changes in atmospheric circulation since the last glaciation.

  4. Alteration of hydrogeomorphic processes by invasive beavers in southern South America.

    PubMed

    Westbrook, Cherie J; Cooper, David J; Anderson, Christopher B

    2017-01-01

    The North American beaver (Castor canadensis) is an invasive species in southern Patagonia, introduced in 1946 as part of a program by the Argentine government to augment furbearers. Research focus has turned from inventorying the beaver's population and ecosystem impacts toward eradicating it from the region and restoring degraded areas. Successful restoration, however, requires a fuller determination of how beavers have altered physical landscape characteristics, and of what landscape features and biota need to be restored. Our goal was to identify changes to the physical landscape by invasive beaver. We analyzed channel and valley morphology in detail at one site in each of the three major forest zones occurring on the Argentine side of Tierra del Fuego's main island. We also assessed 48 additional sites across the three forest biomes on the island to identify a broader range of aquatic habitat occupied and modified by beaver. Beaver build dams with Nothofagus tree branches on streams, which triggered mineral sediment accretion processes in the riparian zone, but not in ways consistent with the beaver meadow theory and only at a few sites. At the majority of sites, beavers actively excavated peat and mineral sediment, moved thousands of cubic meters of sediment within their occupied landscapes and used it to build dams. Beaver were also common in fen ecosystems where pond formation inundated and drowned peat forming mosses and sedges, and triggered a massive invasion of exotic plant species. Results highlight that restoration of fen ecosystems is a previously unrecognized but pressing and challenging restoration need in addition to reforestation of Nothofagus riparian forests. We recommend that decision-makers include the full ecosystem diversity of the Fuegian landscape in their beaver eradiation and ecosystem restoration plans. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. First comprehensive phylogenetic analysis of the genus Erysiphe (Erysiphales, Erysiphaceae) II: the Uncinula lineage.

    PubMed

    Takamatsu, Susumu; Ito Arakawa, Hanako; Shiroya, Yoshiaki; Kiss, Levente; Heluta, Vasyl

    2015-01-01

    Phylogenetic relationships of the Uncinula lineage, which is the basal group in the genus Erysiphe, were investigated with 167 sequences of nuc ITS1-5. 8S-ITS2 and the 28S rDNA regions. Backbone tree analyses with six datasets and two tree-constructing methods revealed that the Uncinula lineage is divided into seven distinct clades. Clades 1-5 each contained a representative powdery mildew species, namely E. australiana in Clade 1, E. liquidambaris in Clade 2, E. adunca in Clade 3, E. fraxinicola in Clade 4 and E. actinidiae in Clade 5. Clade 6 comprises 71 sequences including the Microsphaera lineage and 17 species of the Uncinula lineage, such as E. carpinicola, E. carpinilaxiflorae, E. miyabei, E. glycines and E. necator. Topology tests supported the Microsphaera lineage forming a monophyletic clade in Clade 6, suggesting that Microsphaera-type appendages appeared only once in this clade to diverge into the Microsphaera lineage. Clade 7 consists of 72 sequences containing 30 species, including species of sects. Californiomyces and Typhulochaeta, four species from Nothofagus, species of sect. Erysiphe parasitising herbaceous plants belonging to the Asteraceae, Rosaceae and Saxifragaceae. Molecular clock analysis suggests that the major seven clades appeared 50-30 million years ago (Ma) in the Paleogene Period. The Microsphaera lineage may have split from the Uncinula lineage at the boundary of the Paleogene and Neogene, when appendages with dichotomously branched tips appeared. The clade of the species on Nothofagus split from the northern hemisphere species about 20-10 million years ago (Ma) in the Miocene Epoch, and host-shift from trees to herbs also might have occurred in this period. © 2015 by The Mycological Society of America.

  6. Vegetation, Fire and Climate Over the Last 2000 Yrs in Central West Patagonia (45°S)

    NASA Astrophysics Data System (ADS)

    Villa-Martinez, R. P.; Simi, E. I.; Moreno, P. I.

    2014-12-01

    We report high-resolution pollen and charcoal records from lake sediments obtained from Lago Mellizas and Lago Churrasco to reconstruct the history of vegetation, fire and past variations of the southern westerly winds (SWW) over the last 2000 years. Both sites are located near to the climate-modulated forest-steppe ecotone in central west Patagonia. In this region the SWW are the only source of precipitation and is ideal for reconstructing past changes in atmospheric circulation. This is facilitated by the marked west-east precipitation gradient across the Patagonian Andes that induces a zonation of the regional vegetation which can be used for inferring past changes in precipitation regimes based on fossil pollen records. Furthermore, the Chilean-European colonization process in central west Patagonia started early in the 20th century, allowing characterization of natural vegetation and climate variability in the absence of human disturbance until the end of the 19th century. The pollen records shows dominance of Nothofagus deciduous forests with minor fluctuations and low herb and aquatics abundances, which suggest humid climate conditions. We detect a major change in the pollen stratigraphy at 200 cal yr BP, when started a sustained decreasing trend in Nothofagus, along with increases of Poaceae and aquatics plants (Cyperaceae, Myriophyllum). We interpret these changes as a forest opening and centripetal expansion of littoral environments toward the lake center driven by lake-level lowering in response to lowered precipitation brought by the SWW. Pinus, Rumex, Plantago, which indicate human perturbation, increase in 1900 AD. Macroscopic charcoal increases at 1750, 1400, 850-700, 500, and 200 cal yr BP, suggesting local fires, followed by sharp increases during the last 100 years. We interpret the pre-20th century charcoal peaks as dry intervals with lowered SWW influence. Acknowledgement: Fondecyt 1121141, Fondap 15110009, and ICM grants P02-51 and NC120066.

  7. Environmental change and fire in the Owen Stanley Ranges, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Hope, Geoffrey

    2009-11-01

    Kosipe, an upland valley at 2000 m altitude in the Owen Stanley Ranges of southeastern New Guinea, is known for the discovery of large stone waisted blades dated to 31 400 cal a BP. The purpose of these tools and the nature of occupation are unknown. The altitude is too high for most food crops today and may have stood close to the treeline during the last glaciation. Three pollen and charcoal diagrams from a large swamp in the Kosipe Valley provide a record of swamp and dryland changes for more than 50 000 years. There have been considerable fluctuations in vegetation on the slopes and on the swamp which reflect both environmental change and anthropogenic influences. A gymnosperm-rich forest at the base is replaced by mountain forest dominated by Nothofagus about 42 000 years ago. Fire first becomes apparent across the swamp around 40 000 years ago but is not common during the time when subalpine herbs reach their best representation. Tree fern-rich grasslands form a mosaic with montane forest in a near-treeline environment. The Pleistocene-Holocene boundary is marked by a decline in Nothofagus and increase in lower montane mixed forest taxa. Charcoal increases before this time and the swamp vegetation becomes more grass-rich. Charcoal is at its maximum through the last 3000 years possibly reflecting climate variability as well as sedentary occupation and agriculture on the swamp margin. Supplementary pollen diagrams from two higher altitude sites support the evidence from the Kosipe Swamp cores. Charcoal, local catchment erosion and increases in disturbance taxa become more widespread in the last 5000 years at these sites, suggesting that local settlement at Kosipe may have lagged behind general landscape use by populations from lower altitudes.

  8. 78 FR 15356 - Caribbean Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-11

    ... Sierra-Tourmaline off the West Coast of Puerto Rico--Graciela Garc a-Moliner/Bill Arnold --Shared Jurisdictions: Bajo de Sico and Tourmaline --Seasonal Area Closures Differences in Months SEFSC Queen Snapper...

  9. Human infections of fish-borne trematodes in Vietnam: prevalence and molecular specific identification at an endemic commune in Nam Dinh province.

    PubMed

    De, Nguyen Van; Le, Thanh Hoa

    2011-12-01

    The prevalence of fish-borne trematodes in humans and their molecular identification was investigated in the Rang Dong commune of Nam Dinh province, Vietnam, between January 2009 and December 2010. A total of 405 people in this commune were interviewed on the habit of eating raw fish and all of their stool samples were collected using the Kato-Katz technique for examination of the presence of fish-borne trematodes. The worms (and eggs) were first morphologically examined, counted, described and identified, then the representative isolates were subjected for molecular species confirmation. A total of 385 adult flukes collected from 10 patients were morphologically identified to species and defined as Clonorchis sinensis (14.58%) in Opisthorchiidae family, Haplorchis taichui (32.29%), Haplorchis pumilio (52.08%) and Centrocestus formosanus (1.04%) in Heterophyidae family. A high rate (77.8%) of the interviewees was found to have the habit of eating raw fish. This habit was attributed to the high infection rate of fish-borne trematode in humans (22.72%; OR=2.486). The infection rate of fish-borne trematodes in males was higher (29.3%) than that in females (16.0%) and increased by age, reaching the highest in the patients aged 40-59 years (28.2-28.7%). The infection intensity of fish-borne trematode was found light (336 EPG). Adult flukes were collected from a group of the patients with the highest intensity of infection and subjected to molecular and phylogenetic analysis using a portion (326 bp) of mitochondrial cox1. Phylogenetic tree inferred from cox1 sequences using sequence data for 34 isolates of opisthorchid, heterophyid, fasciolid, paragonimid, schistosomid trematodes and taeniid cestodes revealed that they are distinct groups. The newly collected with the known clonorchid and heterophyid isolates form the well defined taxonomic groups, respectively, confirming that C. sinensis and Haplorchis spp. (H. pumilio and H. taichui) were among the collected samples

  10. Experimental plague infection in South African wild rodents.

    PubMed Central

    Shepherd, A. J.; Leman, P. A.; Hummitzsch, D. E.

    1986-01-01

    Susceptibility studies were undertaken to determine the response of some South African wild rodent species to experimental plague (Yersinia pestis) infection. A degree of plague resistance was found in three gerbil species captured in the plague enzootic region of the northern Cape Province, these being the Namaqua gerbil, Desmodillus auricularis, (LD50 1 X 10(6) organisms), the bushveld gerbil, Tatera leucogaster, (LD50 9.1 X 10(5)) and the highveld gerbil, T. brantsii (LD50 4 X 10(2)). Animals from a population of the four-striped mouse, Rhabdomys pumilio, captured in the plague area of Port Elizabeth, proved moderately resistant to experimental plague infection (LD50 1.3 X 10(4)) while those from another population of the same species captured in a plague-free area of the Orange Free State were extremely susceptible (LD50, 5 organisms). The response of both populations however was a heterogeneous one. Marked differences in susceptibility were also found between two populations of multimammate mice, Mastomys natalensis (2n = 32) although both originated from areas outwith the known distribution of plague in southern Africa. The 50% infectious dose was relatively high in T. leucogaster (3.2 X 10(2)) and D. auricularis (1.7 X 10(3)), but was low (2-16 organisms) in the other rodent species tested. The plague antibody response, determined by enzyme-linked immunosorbent assay (ELISA), was extremely short-lived in T. leucogaster, only 10% of inoculated animals remaining seropositive at low titres after 11 weeks. Antibodies persisted for only slightly longer in the sera of T. brantsii which were reinoculated with 2 X 10(3) plague organisms 6 weeks after initial challenge. The demonstration of the existence of both susceptible and resistant populations of R. pumilio and M. natalensis indicates that these species must be considered as potential plague reservoir hosts in parts of South Africa. The results suggest that resistance to plague infection in previously epizootic

  11. Miocene Antarctic Terrestrial Realm

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A.; Marchant, D. R.

    2009-12-01

    The discovery of several locations in the Transantarctic Mountains that contain macrofossils and pollen is transforming our understanding of late Cenozoic Antarctica. The most southerly location is on the Beardmore Glacier (85.1°S) about 500 km from the South Pole. The environment was an active glacial margin in which plants, insects and freshwater mollusks inhabited the sand and gravel bars and small lakes on an outwash plain. In addition to leaves and wood of dwarf Nothofagus (Southern Beech) shrubs, achenes of Ranunculus (Buttercup), in situ cushion growth forms of mosses and a vascular plant, the assemblages contains various exoskeletal parts of carabid and curculionid beetles and a cyclorrhaphan fly, the shells of freshwater bivalve and gastropod species and a fish tooth. Initially the deposits were assigned a Pliocene age (3.5 Ma) but a mid- to early Miocene age is more probable (c. 14 - 25 Ma) based on correlation of fossil pollen from the deposits with 39Ar/40Ar dated pollen assemblages from the McMurdo Dry Valleys locations. The oldest location within the Dry Valleys also involved an active ice margin but was part of a valley system that was completely deglaciated for intervals long enough for thick paleosols to develop. The Friis Hills fossil deposits of the Taylor Valley region (77.8°S) are at least 19.76 Ma based on the 39Ar/40Ar age of a volcanic ash bed. The valley floor during the non-glacial phases had poorly-drained soils and the extensive development of mossy mires. Wood and leaves of Nothofagus are abundant in lacustrine deposits. The silts of shallow fluvial channels contain abundant megaspores and spiky leaves of the aquatic lycopod Isoetes (Quillwort). Fossils of beetles are also present in these deposits. During the glacial phases, proglacial lakes were surrounded by dwarfed, deciduous Nothofagus shrubs. The youngest fossils recovered from the Dry Valleys are from the Olympus Range (77.5°S) with an age of 14.07 Ma. The environment was an

  12. Early to mid-Miocene palaeoclimate of Antarctica based on terrestrial records

    NASA Astrophysics Data System (ADS)

    Ashworth, Allan; Lewis, Adam

    2017-04-01

    Paleontological and stratigraphic studies of sites in the Transantarctic Mountains (TAM) are advancing knowledge of the landscape, vegetation and climate that existed immediately before the growth of the modern East Antarctic Ice Sheet. The sites are located in the Friis Hills and the western Olympus Range in the McMurdo Dry Valleys. In both localities, parts of ancient landscapes are preserved on upland surfaces high above modern valley floors. The early to mid-Miocene interval is bracketed by 40Ar/39Ar ages on volcanic ashes of 19.76 ± 0.11 Ma to 13.85 ± 0.03 Ma. Like all glacial records it is discontinuous but even so several trends can be detected. The record is one of an evolving glacial system during which ice caps coalesced to form an ice sheet. Initially, small alpine glaciers flowed southwestward toward the continental interior eroding shallow troughs into granitic bedrock. By the close of the interval, large glaciers flowed eastward from the continental interior to the Ross Sea. The interval was marked by numerous glacial advances and retreats. Tills are matrix-rich, and outwash sands and gravels ripple-laminated and cross-bedded, typical of those associated with wet-based glaciation. The vegetation during the interval was in a dynamic flux retreating downslope during glacial advances and recolonizing valleys after retreats. Fossils accumulated in peat beds and organic silts representing lacustrine, fluvial and paludal environments. Fossils include diatoms, fungal ascomycetes, pollen and spores, lycopod megaspores, mosses, wood and leaves of Nothofagus (southern beech), fruits of vascular plants, and insect skeletal parts of Diptera (flies) and Coleoptera (beetles). The vegetation was a tundra, initially shrub- and later moss-dominated. During the interval there was a marked decline in biodiversity. Initially, there were 4 species of Nothofagus represented by different leaf types and at least 9 species of vascular plants by their seeds. At the close of

  13. Climate-vegetation-fire linkages on decadal-to-millennial time scales along the Patagonian forest-steppe ecotone (41 - 43°S)

    NASA Astrophysics Data System (ADS)

    Iglesias, V.; Whitlock, C. L.

    2013-12-01

    Patagonian vegetation has dramatically changed in composition and distribution over the last 16,000 years. Although patterns of vegetation change are relatively clear, our understanding of the processes that produce them is limited. In this study, we reconstructed the vegetation and fire history of the North Patagonian forest-steppe ecotone (41 - 43°S) and linked past ecological changes to variations in large-scale synoptic controls of climate and past human activity. Postglacial vegetation and fire dynamics were inferred from high-resolution pollen and charcoal records from seven lakes located along the forest-steppe ecotone in the eastern flanks of the Andes. We fit Mixed Generalized Additive Models to these time series to estimate regional trends in vegetation composition and biomass burning through time, and compared them with independent paleoclimate data so as to assess long-term vegetation-fire-climate linkages. Pollen data indicate that late-glacial steppe was replaced by open forest in the early Holocene and by closed forest in the middle and late Holocene. Fire activity was lowest during the late-glacial to early-Holocene transition and gradually increased through the Holocene. Long-term vegetation and fire patterns responded to variations in seasonal and annual insolation and their effect on moisture during the growing season. Submillennial-scale precipitation variability explained much of the fine-scale ecotonal behavior, mainly through its effect on fire, which can amplify or override the direct influence of climate on ecotone composition. During the late Holocene, in particular, century-long oscillations in forest composition were largely driven by changes in humidity, associated with the strengthening of the westerlies and ENSO variability. Humid periods (4900-3800 cal yr BP, 2850-1350 cal yr BP) promoted Nothofagus forest, and dry times (3800-2850 cal yr BP, 1350-450 cal yr BP) favored Austrocedrus expansion. At intermediate moisture levels

  14. The early to mid-Miocene environment of Antarctica

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A.

    2012-12-01

    Paleoecological studies in the Transantarctic Mountains of the McMurdo region provide evidence that the climate was both warmer and wetter in the early to mid-Miocene than it was during the late Miocene. The climate change was accompanied by a shift from wet- to cold-based glaciation in the TAM and the probable growth of the polar ice sheet. Terrestrial and freshwater aquatic fossil assemblages from the Friis Hills (77°S) and the Olympus Range (77°S), with endpoint 40Ar/39Ar ages on tephras of 19.76 Ma and 14.07 Ma, respectively, indicate climatic cooling during the interval. At c.14 Ma, the temperature dropped below the threshold required to support the plants and insects of a tundra biome, and they became extinct. This interpretation is supported by pollen studies from Ross Sea cores. The extinction of the tundra biota on the continent appears to have been time-transgressive, occurring at 12.8 Ma on the Antarctic Peninsula. Evidence of climatic cooling from early to mid-Miocene is based on a decrease in biodiversity. During interglacial phases of the early Miocene, the poorly drained valley of the Friis Hills supported a sexually-reproducing moss community dominated by Campylium cf. polygamum, which today grows on the margins of lakes and in soil between boulders. Wood and leaves of Nothofagus (Southern Beech), and the seeds of at least five other angiosperm species are preserved as fossils. In addition, there are abundant megaspores and spiny, curved leaves of the aquatic lycopod Isoetes (Quillwort), as well as chitinous remains of curculionid beetles and Chironomidae (midges). During glacial phases, the only fossils found are Nothofagus leaves of a species which appears to be different than that associated with the interglacial phases. Pollen supports the interpretation that there was more than one species of Nothofagus in the vegetation. The types and numbers of species indicate that the vegetation was a shrub tundra. The closest modern analog for the fossil

  15. Lacustrine Records of Holocene Climate Change From Southernmost South America

    NASA Astrophysics Data System (ADS)

    Moy, C. M.; Francois, J.; Moreno, P. I.; Dunbar, R. B.; Villa-Martinez, R.; Waldmann, N.; Ariztegui, D.

    2005-12-01

    The westerly wind field is one of the most prominent atmospheric circulation features in the Southern Hemisphere, which has a major impact on the climate of southern South America and hydrographic conditions in the Southern Ocean. Recent studies have argued that latitudinal shifts in the westerly boundaries during the LGM played a role in the modulation of atmospheric CO2 through positive feedback mechanisms within the Southern Ocean. However, significant discrepancies exist among paleoclimate records and GCM simulations. Here we present lacustrine records of late Holocene climate variability from two sites in southern South America. The first, a 4.75 meter sediment core from Laguna Guanacos (51°S, 72°W) in Southern Patagonia, provides a continuous record of climatic change related to the westerly wind regime during the last ~11,000 14C yrs. The sediment cores obtained from this small, shallow closed-basin lake reveal high concentrations of organic mater and biogenic carbonate. Eleven AMS radiocarbon dates on organic and carbonate fractions indicate that the record spans the last ~13,000 calendar years and modern dates from core tops suggest little influence by old or dead carbon sources. Combined pollen, stable isotope and elemental data indicate that significant shifts in the forest-steppe ecotone have occurred during the late Holocene. Increases in C/N and Nothofagus/Graminae index values culminating between 100 and 550 14C yrs BP are indicative of forest expansion related to cooler and moister conditions during the Little Ice Age. A large >2‰ decrease in bulk organic δ13C and a concomitant decrease in Nothofagus and rise in Rumex during the last 100 years, marks extensive burning of the region and the replacement of a forested landscape by an anthropogenic-set steppe. A positive linear relationship between δ18O and δ13C on bi-valves and ostracodes indicates that the lake behaves as a closed system and will be sensitive to changes in moisture balance

  16. Environmental changes in two lakes of Northern Patagonia (Chile): A 1000 yr reconstruction based on pollen and charcoal

    NASA Astrophysics Data System (ADS)

    Nicole, Vargas; Laura, Torres; Alberto, Araneda; Fabiola, Cruces; Fernando, Torrejón; Denisse, Alvarez; G, Bizama; Nathalie, Fagel; Roberto, Urrutia

    2010-05-01

    We aim to reconstruct the environmental changes experimented in Patagonian ecosystems during the last 1000 years. We analyze sediment cores from two lakes (Thompson and Burgos), located in Aysen Region, Southern Chile. The samples were obtained using a gravity corer and sampled at intervals of 1 cm to 30 cm depth and every 5 cm until the end of the core. Thompson lake sediment core was sampled every 5 cm. Age model is based on radiocarbon datings on bulk sediments and macroremains. In Burgos lake we evidence two main climatic changes. A wet period between 876-1444 AD is marked by the presence of Pteridophytes. A colder and dryer period is then evidenced by an increase of Berberis sp between 1444 and 1656 AD. From 1834 AD to Present the sediment record is mainly affected by human activities. High concentrations of carbon particles and a sharp change in pollen assemblage (increase of Poaceae, decrease of Nothofagus dombeyi-Type) are indicators of two large fire events. The lacustrine sediment of Thompson is characterized by a wetter period, between 874 - 1168 AD, with abundance of Pteridophytes. Then from 1168 AD to Present the environmental conditions of the watershed were characterized by lower ferns and fire events. Two major fires were evidenced between 1850 AD and Present. Like in Burgos they are marked by major changes in plant associations (sharp increase in Poaceae, drastic loss of Nothofagus dombeyi-Type). Wet periods identified in both lakes at the base of the sediment record could correspond to manifestations of a warm climate anomaly like the Medieval Warm Period. The dry and cold period, especially obvious in the Burgos record, could be associated to a cold climate anomaly. Finally the great changes in vegetation that occurred from the year ~ 1830 in the basin of the two lakes were directly related to human activities (forest cutting) developed during the ninetheenth and twentieth centuries. This research is funded by both Chilean and Belgian projects

  17. The vegetation cover of New Zealand at the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Newnham, Rewi; McGlone, Matt; Moar, Neville; Wilmshurst, Janet; Vandergoes, Marcus

    2013-08-01

    A new reconstruction of the vegetation cover for New Zealand at the Last Glacial Maximum (LGM) is presented, based primarily on a database of 66 pollen site records and a more limited range of plant macrofossil and coleopteran records. Extensive forest is evident only from Auckland northwards. Conifer-broadleaf forest similar to that in the region today, but with Agathis australis scarce, persisted in the far north, whilst Nothofagus trees and a range of shrub taxa characterised the more open forests elsewhere in Northland. Survival of Nothofagus-dominated forest in coastal and exposed continental shelf locations to the southwest of Auckland and northwestern South Island is also indicated. Beyond these regions, vegetation cover comprised shrubland- and grassland-dominant communities, with the latter more prominent in eastern areas, to the south and presumably at higher altitudes. Nevertheless the survival of forest trees is indicated unambiguously in most regions apart from the eastern South Island. Thus the concept of 'micro glacial forest refugia' in New Zealand remains supported by this latest glacial vegetation reconstruction and we draw possible parallels with the developing but contentious concept of 'northern cryptic refugia' in Europe. Recent assertions that pollen and beetle reconstructions of the New Zealand LGM vegetation patterns diverge significantly are not supported by this analysis. Rather, the two proxies are readily reconciled if the term 'woody' as indicated by coleoptera is not restricted to tall forest trees but extended to the widespread woody shrub and small tree elements of the New Zealand flora. Regional distinctions in the LGM vegetation reconstruction concur broadly with the contemporary vegetation pattern, suggesting that, along with temperature depression and likely drier growing conditions, a zonal circulation regime with prominent southern westerly winds was important at 21 ka, as it is today. Pollen-climate modelling of the extent of

  18. Biochemical characterization of the Caenorhabditis elegans FBF.CPB-1 translational regulation complex identifies conserved protein interaction hotspots.

    PubMed

    Menichelli, Elena; Wu, Joann; Campbell, Zachary T; Wickens, Marvin; Williamson, James R

    2013-02-22

    Caenorhabditis elegans CPB-1 (cytoplasmic polyadenylation element binding protein homolog-1) and FBF (fem-3 mRNA binding factor) are evolutionary conserved regulators of mRNA translation that belong to the CPEB (cytoplasmic polyadenylation element binding) and PUF (Pumilio and FBF) protein families, respectively. In hermaphrodite worms, CPB-1 and FBF control key steps during germline development, including stem cell maintenance and sex determination. While CPB-1 and FBF are known to interact, the molecular basis and function of the CPB-1⋅FBF complex are not known. The surface of CPB-1 that interacts with FBF was localized using in vivo and in vitro methods to a 10-residue region at the N-terminus of the protein and these residues are present in the FBF-binding protein GLD-3 (germline development defective-3). PUF proteins are characterized by the presence of eight α-helical repeats (PUF repeats) arranged side by side in an elongated structure. Critical residues for CPB-1 binding are found in the extended loop that connects PUF repeats 7 and 8. The same FBF residues also mediate binding to GLD-3, indicating a conserved binding mode between different protein partners. CPB-1 binding was competitive with GLD-3, suggestive of mutual exclusivity in vivo. RNA binding measurements demonstrated that CPB-1 alters the affinity of FBF for specific RNA sequences, implying a functional model where the coregulatory protein CPB-1 modulates FBF target selection. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Arginine vasopressin plasma levels change seasonally in African striped mice but do not differ between alternative reproductive tactics.

    PubMed

    Schoepf, Ivana; Schradin, Carsten

    2014-08-01

    Arginine vasopressin (AVP) is an important hormone for osmoregulation, while as a neuropeptide in the brain it plays an important role in the regulation of social behaviors. Dry habitats are often the home of obligately sociable species such as meerkats and Damaraland mole-rats, leading to the hypothesis that high plasma AVP levels needed for osmoregulation might be associated with the regulation of social behavior. We tested this in a facultative sociable species, the African striped mouse (Rhabdomys pumilio). During the moist breeding season, both solitary- and group-living reproductive tactics occur in this species, which is obligatory sociable in the dry season. We collected 196 plasma samples from striped mice following different reproductive tactics both during the moist and the dry season. Solitary mice did not have lower AVP levels than sociable mice, rejecting the hypothesis that peripheral AVP is involved in the regulation of alternative reproductive tactics. However, we found significantly higher AVP levels during the dry season, with AVP levels correlated with the abundance of food plants, the main source of water for striped mice. Plasma AVP levels were not correlated with testosterone or corticosterone levels. Our study underlines the important role that AVP plays in osmoregulation, particularly for a free ranging mammal living under harsh arid conditions.

  20. Dental microwear of sympatric rodent species sampled across habitats in southern Africa: Implications for environmental influence.

    PubMed

    Burgman, Jenny H E; Leichliter, Jennifer; Avenant, Nico L; Ungar, Peter S

    2016-03-01

    Dental microwear textures have proven to be a valuable tool for reconstructing the diets of a wide assortment of fossil vertebrates. Nevertheless, some studies have recently questioned the efficacy of this approach, suggesting that aspects of habitat unrelated to food preference, especially environmental grit load, might have a confounding effect on microwear patterning that obscures the diet signal. Here we evaluate this hypothesis by examining microwear textures of 3 extant sympatric rodent species that vary in diet breadth and are found in a variety of habitat types: Mastomys coucha, Micaelamys namaquensis and Rhabdomys pumilio. We sample each of these species from 3 distinct environmental settings in southern Africa that differ in rainfall and vegetative cover: Nama-Karoo shrublands (semi-desert) and Dry Highveld grasslands in the Free State Province of South Africa, and Afromontane (wet) grasslands in the highlands of Lesotho. While differences between habitat types are evident for some of the species, inconsistency in the pattern suggests that the microwear signal is driven by variation in foods eaten rather than grit-level per se. It is clear that, at least for species and habitats sampled in the current study, environmental grit load does not swamp diet-related microwear signatures.

  1. Enzymatic activity of rodents acclimated to cold and long scotophase

    NASA Astrophysics Data System (ADS)

    Fourie, F. Le R.; Haim, A.

    1980-09-01

    Rodents representative of a diurnal species ( Rhabdomys pumilio) as well as a nocturnal species ( Praomys natalensis) were acclimated to cold (Ta = 8°C) at a photoperiod of LD 12:12 and a long scotophase (LD 8; 16) at a temperature of 25° C(Ta). Control groups were kept for both species at Ta = 25° C and LD 12:12 and winter acclimated individuals were obtained during July and August to serve as further reference. Blood samples obtained from the tail were analysed for enzymes representative of three major biochemical pathways. The enzymatic activity of LDH (glycolytic pathway), MDH (Krebs cycle) and G6PDH (hexose monophosphate shunt, as an indicator of gonadal activity) were monitored to represent metabolic activity of the respective cycles. Cold acclimated as well as winter acclimatized mice revealed similar enzymatic patterns for both species and significant increases in LDH and MDH were recorded with a concurrent decrease in G6PDH activity. Specimens exposed to long scotophase exhibited similar enzymatic patterns for both species studied, but enzymatic activity was higher than those of cold acclimated individuals. From these results it is concluded that cold as well as long scotophase induce metabolic adaptations through biochemical activity in the experimental animals. The effect of long scotophase is assumed to be an important factor in the induction of winter acclimatization.

  2. Structural basis for specific recognition of multiple mRNA targets by a PUF regulatory protein

    SciTech Connect

    Wang, Yeming; Opperman, Laura; Wickens, Marvin; Tanaka Hall, Traci M.

    2011-11-02

    Caenorhabditis elegans fem-3 binding factor (FBF) is a founding member of the PUMILIO/FBF (PUF) family of mRNA regulatory proteins. It regulates multiple mRNAs critical for stem cell maintenance and germline development. Here, we report crystal structures of FBF in complex with 6 different 9-nt RNA sequences, including elements from 4 natural mRNAs. These structures reveal that FBF binds to conserved bases at positions 1-3 and 7-8. The key specificity determinant of FBF vs. other PUF proteins lies in positions 4-6. In FBF/RNA complexes, these bases stack directly with one another and turn away from the RNA-binding surface. A short region of FBF is sufficient to impart its unique specificity and lies directly opposite the flipped bases. We suggest that this region imposes a flattened curvature on the protein; hence, the requirement for the additional nucleotide. The principles of FBF/RNA recognition suggest a general mechanism by which PUF proteins recognize distinct families of RNAs yet exploit very nearly identical atomic contacts in doing so.

  3. Specificity factors in cytoplasmic polyadenylation

    PubMed Central

    Charlesworth, Amanda; Meijer, Hedda A; de Moor, Cornelia H

    2013-01-01

    Poly(A) tail elongation after export of an messenger RNA (mRNA) to the cytoplasm is called cytoplasmic polyadenylation. It was first discovered in oocytes and embryos, where it has roles in meiosis and development. In recent years, however, has been implicated in many other processes, including synaptic plasticity and mitosis. This review aims to introduce cytoplasmic polyadenylation with an emphasis on the factors and elements mediating this process for different mRNAs and in different animal species. We will discuss the RNA sequence elements mediating cytoplasmic polyadenylation in the 3′ untranslated regions of mRNAs, including the CPE, MBE, TCS, eCPE, and C-CPE. In addition to describing the role of general polyadenylation factors, we discuss the specific RNA binding protein families associated with cytoplasmic polyadenylation elements, including CPEB (CPEB1, CPEB2, CPEB3, and CPEB4), Pumilio (PUM2), Musashi (MSI1, MSI2), zygote arrest (ZAR2), ELAV like proteins (ELAVL1, HuR), poly(C) binding proteins (PCBP2, αCP2, hnRNP-E2), and Bicaudal C (BICC1). Some emerging themes in cytoplasmic polyadenylation will be highlighted. To facilitate understanding for those working in different organisms and fields, particularly those who are analyzing high throughput data, HUGO gene nomenclature for the human orthologs is used throughout. Where human orthologs have not been clearly identified, reference is made to protein families identified in man. © 2013 John Wiley & Sons, Ltd. PMID:23776146

  4. A universal strategy for regulating mRNA translation in prokaryotic and eukaryotic cells

    PubMed Central

    Cao, Jicong; Arha, Manish; Sudrik, Chaitanya; Mukherjee, Abhirup; Wu, Xia; Kane, Ravi S.

    2015-01-01

    We describe a simple strategy to control mRNA translation in both prokaryotic and eukaryotic cells which relies on a unique protein–RNA interaction. Specifically, we used the Pumilio/FBF (PUF) protein to repress translation by binding in between the ribosome binding site (RBS) and the start codon (in Escherichia coli), or by binding to the 5′ untranslated region of target mRNAs (in mammalian cells). The design principle is straightforward, the extent of translational repression can be tuned and the regulator is genetically encoded, enabling the construction of artificial signal cascades. We demonstrate that this approach can also be used to regulate polycistronic mRNAs; such regulation has rarely been achieved in previous reports. Since the regulator used in this study is a modular RNA-binding protein, which can be engineered to target different 8-nucleotide RNA sequences, our strategy could be used in the future to target endogenous mRNAs for regulating metabolic flows and signaling pathways in both prokaryotic and eukaryotic cells. PMID:25845589

  5. Community structure of fleas within and among populations of three closely related rodent hosts: nestedness and beta-diversity.

    PubMed

    VAN DER Mescht, Luther; Krasnov, Boris R; Matthee, Conrad A; Matthee, Sonja

    2016-09-01

    We studied nestedness and its relationships with beta-diversity in flea communities harboured by three closely related rodent species (Rhabdomys pumilio, Rhabdomys intermedius, Rhabdomys dilectus) at two spatial scales (within and among host populations) in South Africa and asked (a) whether variation in species composition of flea communities within and among host populations follows a non-random pattern; if yes, (b) what are the contributions of nestedness and species turnover to dissimilarity (= beta-diversity) among flea communities at the two scales; and (c) do the degree of nestedness and its contribution to beta-diversity differ among host species (social vs solitary) and between scales. We found that nestedness in flea assemblages was more pronounced (a) in social than solitary host species and (b) at lower (among host individuals within populations) than at higher scale (among host populations). We also found that higher degree of nestedness was associated with its higher contribution to beta-diversity. Our findings support earlier ideas that parasite community structure results from the processes of parasite accumulation by hosts rather than from the processes acting within parasite communities.

  6. Experimental increase of testosterone increases boldness and decreases anxiety in male African striped mouse helpers.

    PubMed

    Raynaud, Julien; Schradin, Carsten

    2014-04-22

    Males of many species can adjust their behaviors to environmental conditions by changing reproductive tactics. Testosterone surges in adult breeding males typically inhibit the expression of paternal care while facilitating the expression of aggression during environmental changes. Similarly, in non-breeding philopatric males of cooperatively breeding species, up-regulation of testosterone may inhibit alloparental care while facilitating dispersal, i.e. males might become bolder and more explorative. We tested this hypothesis in philopatric male African striped mice, Rhabdomys pumilio. Striped mouse males can either remain in their natal groups providing alloparental care or they can disperse seeking mating opportunities. Compared to philopatric males, dispersed males typically show higher testosterone levels and lower corticosterone levels, and more aggression toward pups and same sex conspecifics. We experimentally increased the testosterone levels of the philopatric males kept in their family groups when pups were present. Testosterone-treated males did not differ significantly from control males in alloparental care and in aggression toward same-sex conspecifics. Compared to the control males, testosterone treated males were bolder, more active, and less anxious; they also showed lower corticosterone levels. The philopatric males were sensitive to our testosterone treatment for dispersal- and anxiety-like behavior but insensitive for social behaviors. Our results suggest a role of testosterone in dispersal.

  7. Calcium-dependent N-cadherin up-regulation mediates reactive astrogliosis and neuroprotection after brain injury.

    PubMed

    Kanemaru, Kazunori; Kubota, Jun; Sekiya, Hiroshi; Hirose, Kenzo; Okubo, Yohei; Iino, Masamitsu

    2013-07-09

    Brain injury induces phenotypic changes in astrocytes, known as reactive astrogliosis, which may influence neuronal survival. Here we show that brain injury induces inositol 1,4,5-trisphosphate (IP3)-dependent Ca(2+) signaling in astrocytes, and that the Ca(2+) signaling is required for astrogliosis. We found that type 2 IP3 receptor knockout (IP3R2KO) mice deficient in astrocytic Ca(2+) signaling have impaired reactive astrogliosis and increased injury-associated neuronal death. We identified N-cadherin and pumilio 2 (Pum2) as downstream signaling molecules, and found that brain injury induces up-regulation of N-cadherin around the injured site. This effect is mediated by Ca(2+)-dependent down-regulation of Pum2, which in turn attenuates Pum2-dependent translational repression of N-cadherin. Furthermore, we show that astrocyte-specific knockout of N-cadherin results in impairment of astrogliosis and neuroprotection. Thus, astrocytic Ca(2+) signaling and the downstream function of N-cadherin play indispensable roles in the cellular responses to brain injury. These findings define a previously unreported signaling axis required for reactive astrogliosis and neuroprotection following brain injury.

  8. Calcium-dependent N-cadherin up-regulation mediates reactive astrogliosis and neuroprotection after brain injury

    PubMed Central

    Kanemaru, Kazunori; Kubota, Jun; Sekiya, Hiroshi; Hirose, Kenzo; Okubo, Yohei; Iino, Masamitsu

    2013-01-01

    Brain injury induces phenotypic changes in astrocytes, known as reactive astrogliosis, which may influence neuronal survival. Here we show that brain injury induces inositol 1,4,5-trisphosphate (IP3)-dependent Ca2+ signaling in astrocytes, and that the Ca2+ signaling is required for astrogliosis. We found that type 2 IP3 receptor knockout (IP3R2KO) mice deficient in astrocytic Ca2+ signaling have impaired reactive astrogliosis and increased injury-associated neuronal death. We identified N-cadherin and pumilio 2 (Pum2) as downstream signaling molecules, and found that brain injury induces up-regulation of N-cadherin around the injured site. This effect is mediated by Ca2+-dependent down-regulation of Pum2, which in turn attenuates Pum2-dependent translational repression of N-cadherin. Furthermore, we show that astrocyte-specific knockout of N-cadherin results in impairment of astrogliosis and neuroprotection. Thus, astrocytic Ca2+ signaling and the downstream function of N-cadherin play indispensable roles in the cellular responses to brain injury. These findings define a previously unreported signaling axis required for reactive astrogliosis and neuroprotection following brain injury. PMID:23798419

  9. Comparative morphology of eggs of the Haplorchiinae (Trematoda: Heterophyidae) and some other medically important heterophyid and opisthorchiid flukes.

    PubMed

    Ditrich, O; Giboda, M; Scholz, T; Beer, S A

    1992-01-01

    The egg morphology of the following medically important small flukes from Southeast Asia and Far East were studied: Opisthorchis viverrini, Clonorchis sinensis (Opisthorchiidae), Haplorchis taichui, H. pumilio, H. yokogawai, Stellantchasmus falcatus and Metagonimus sp. (Heterophydiae). This study revealed a great intraspecific variability and interspecific similarity in size and shape of eggs. The eggs shape does not seem to be suitable for species identification. On the other hand, biometrical analysis of egg size enabled us to divide eggs from the species studied into four distinct groups according to the Faust-Meleney index (FMI) characterizing egg size rather than the length and width of eggs. The surface structures of eggs, delineated by using a scanning electron microscope (SEM), appeared to be a suitable morphological feature for distinguishing some groups of small flukes. Eggs from the Haplorchiinae were typified by the characteristic filamentous mesh structure. The problems of identification of eggs in human stool samples and suitability of using morphological criteria such as shape and size of eggs are discussed herein.

  10. Germ line determinants are not localized early in sea urchin development, but do accumulate in the small micromere lineage.

    PubMed

    Juliano, Celina E; Voronina, Ekaterina; Stack, Christie; Aldrich, Maryanna; Cameron, Andrew R; Wessel, Gary M

    2006-12-01

    Two distinct modes of germ line determination are used throughout the animal kingdom: conditional-an inductive mechanism, and autonomous-an inheritance of maternal factors in early development. This study identifies homologs of germ line determinants in the sea urchin Strongylocentrotus purpuratus to examine its mechanism of germ line determination. A list of conserved germ-line associated genes from diverse organisms was assembled to search the S. purpuratus genome for homologs, and the expression patterns of these genes were examined during embryogenesis by whole mount in situ RNA hybridization and QPCR. Of the 14 genes tested, all transcripts accumulate uniformly during oogenesis and Sp-pumilio, Sp-tudor, Sp-MSY, and Sp-CPEB1 transcripts are also uniformly distributed during embryonic development. Sp-nanos2, Sp-seawi, and Sp-ovo transcripts, however, are enriched in the vegetal plate of the mesenchyme blastula stage and Sp-vasa, Sp-nanos2, Sp-seawi, and Sp-SoxE transcripts are localized in small micromere descendents at the tip of the archenteron during gastrulation and are then enriched in the left coelomic pouch of larvae. The results of this screen suggest that sea urchins conditionally specify their germ line, and support the hypothesis that this mechanism is the basal mode of germ line determination amongst deuterostomes. Furthermore, accumulation of germ line determinants selectively in small micromere descendents supports the hypothesis that these cells contribute to the germ line.

  11. UIS2: A Unique Phosphatase Required for the Development of Plasmodium Liver Stages

    PubMed Central

    Zhang, Min; Mishra, Satish; Sakthivel, Ramanavelan; Fontoura, Beatriz M. A.; Nussenzweig, Victor

    2016-01-01

    Plasmodium salivary sporozoites are the infectious form of the malaria parasite and are dormant inside salivary glands of Anopheles mosquitoes. During dormancy, protein translation is inhibited by the kinase UIS1 that phosphorylates serine 59 in the eukaryotic initiation factor 2α (eIF2α). De-phosphorylation of eIF2α-P is required for the transformation of sporozoites into the liver stage. In mammalian cells, the de-phosphorylation of eIF2α-P is mediated by the protein phosphatase 1 (PP1). Using a series of genetically knockout parasites we showed that in malaria sporozoites, contrary to mammalian cells, the eIF2α-P phosphatase is a member of the PP2C/PPM phosphatase family termed UIS2. We found that eIF2α was highly phosphorylated in uis2 conditional knockout sporozoites. These mutant sporozoites maintained the crescent shape after delivery into mammalian host and lost their infectivity. Both uis1 and uis2 were highly transcribed in the salivary gland sporozoites but uis2 expression was inhibited by the Pumilio protein Puf2. The repression of uis2 expression was alleviated when sporozoites developed into liver stage. While most eukaryotic phosphatases interact transiently with their substrates, UIS2 stably bound to phosphorylated eIF2α, raising the possibility that high-throughput searches may identify chemicals that disrupt this interaction and prevent malaria infection. PMID:26735921

  12. APUM23, a PUF family protein, functions in leaf development and organ polarity in Arabidopsis.

    PubMed

    Huang, Tengbo; Kerstetter, Randall A; Irish, Vivian F

    2014-03-01

    The normal biological function of leaves, such as intercepting light and exchanging gases, relies on proper differentiation of adaxial and abaxial polarity. KANADI (KAN) genes, members of the GARP family, are key regulators of abaxial identity in leaf morphogenesis. This study identified a mutant allele (apum23-3) of APUM23, which encodes a Pumilio/PUF domain protein and acts as an enhancer of the kan mutant. Arabidopsis APUM23 has been shown to function in pre-rRNA processing and play pleiotropic roles in plant development. The apum23-3 mutant also synergistically interacts with other leaf polarity mutants, affects proliferation of division-competent cells, and alters the expression of important leaf polarity genes. These phenotypes show that APUM23 has critical functions in plant development, particularly in polarity formation. The PUF gene family is conserved across kingdoms yet it has not been well characterized in plants. These results illuminating the functions of APUM23 suggest a novel role for PUF genes in Arabidopsis leaf development.

  13. APUM23, a PUF family protein, functions in leaf development and organ polarity in Arabidopsis

    PubMed Central

    Huang, Tengbo

    2014-01-01

    The normal biological function of leaves, such as intercepting light and exchanging gasses, relies on proper differentiation of adaxial and abaxial polarity. KANADI (KAN) genes, members of the GARP family, are key regulators of abaxial identity in leaf morphogenesis. This study identified a mutant allele (apum23-3) of APUM23, which encodes a Pumilio/PUF domain protein and acts as an enhancer of the kan mutant. Arabidopsis APUM23 has been shown to function in pre-rRNA processing and play pleiotropic roles in plant development. The apum23-3 mutant also synergistically interacts with other leaf polarity mutants, affects proliferation of division-competent cells, and alters the expression of important leaf polarity genes. These phenotypes show that APUM23 has critical functions in plant development, particularly in polarity formation. The PUF gene family is conserved across kingdoms yet it has not been well characterized in plants. These results illuminating the functions of APUM23 suggest a novel role for PUF genes in Arabidopsis leaf development. PMID:24449383

  14. Basal blood glucose concentration in free-living striped mice is influenced by food availability, ambient temperature and social tactic.

    PubMed

    Schradin, Carsten; Pillay, Neville; Kondratyeva, Anna; Yuen, Chi-Hang; Schoepf, Ivana; Krackow, Sven

    2015-05-01

    Vertebrates obtain most of their energy through food, which they store mainly as body fat or glycogen, with glucose being the main energy source circulating in the blood. Basal blood glucose concentration (bBGC) is expected to remain in a narrow homeostatic range. We studied the extent to which bBGC in free-living African striped mice (Rhabdomys pumilio) is influenced by ecological factors with a bearing on energy regulation, i.e. food availability, abiotic environmental variation and social tactic. Striped mice typically form extended family groups that huddle together at night, reducing energetic costs of thermoregulation, but solitary individuals also occur in the population. We analysed 2827 blood samples from 1008 individuals of seven different social categories that experienced considerable variation in food supply and abiotic condition. Blood samples were taken from mice in the morning after the overnight fast and before foraging. bBGC increased significantly with food plant abundance and decreased significantly with minimum daily ambient temperature. Solitary striped mice had significantly higher bBGC than group-living striped mice. Our results suggest that adaptive responses of bBGC occur and we found large natural variation, indicating that bBGC spans a far greater homeostatic range than previously thought.

  15. A universal strategy for regulating mRNA translation in prokaryotic and eukaryotic cells.

    PubMed

    Cao, Jicong; Arha, Manish; Sudrik, Chaitanya; Mukherjee, Abhirup; Wu, Xia; Kane, Ravi S

    2015-04-30

    We describe a simple strategy to control mRNA translation in both prokaryotic and eukaryotic cells which relies on a unique protein-RNA interaction. Specifically, we used the Pumilio/FBF (PUF) protein to repress translation by binding in between the ribosome binding site (RBS) and the start codon (in Escherichia coli), or by binding to the 5' untranslated region of target mRNAs (in mammalian cells). The design principle is straightforward, the extent of translational repression can be tuned and the regulator is genetically encoded, enabling the construction of artificial signal cascades. We demonstrate that this approach can also be used to regulate polycistronic mRNAs; such regulation has rarely been achieved in previous reports. Since the regulator used in this study is a modular RNA-binding protein, which can be engineered to target different 8-nucleotide RNA sequences, our strategy could be used in the future to target endogenous mRNAs for regulating metabolic flows and signaling pathways in both prokaryotic and eukaryotic cells.

  16. An experimental test for age-related improvements in reproductive performance in a frog that cares for its young

    NASA Astrophysics Data System (ADS)

    Dugas, Matthew B.; Moore, Michael P.; Wamelink, Caitlin N.; Richards-Zawacki, Corinne L.; Martin, Ryan A.

    2015-10-01

    Reproductive performance often increases with age in long-lived iteroparous organisms, a pattern that can result from within-individual increases in effort and/or competence. In free-living populations, it is typically difficult to distinguish these mechanisms or to isolate particular features of reproduction-influencing outcomes. In captive Oophaga pumilio, a frog in which mothers provide extended offspring provisioning via trophic eggs, we experimentally manipulated the age at which females started breeding and then monitored them across repeated reproductive events. This experiment allowed us to decouple age and experience and isolate maternal care as the proximate source of any differences in performance. Younger first-time mothers produced larger broods than older first-time mothers, but did not rear more offspring to independence. Across repeated reproductive events, maternal age was unassociated with any metric of performance. At later reproductive events, however, mothers produced fewer metamorphs, and a lower proportion of individuals in their broods reached independence. These patterns suggest that performance does not improve with age or breeding experience in this frog, and that eventual declines in performance are driven by reproductive activity, not age per se. Broadly, age-specific patterns of reproductive performance may depend on the proximate mechanism by which parents influence offspring fitness and how sensitive these are to effort and competence.

  17. Pseudouridine and N(6)-methyladenosine modifications weaken PUF protein/RNA interactions.

    PubMed

    Vaidyanathan, Pavanapuresan P; AlSadhan, Ishraq; Merriman, Dawn K; Al-Hashimi, Hashim M; Herschlag, Daniel

    2017-05-01

    RNA modifications are ubiquitous in biology, with over 100 distinct modifications. While the vast majority were identified and characterized on abundant noncoding RNA such as tRNA and rRNA, the advent of sensitive sequencing-based approaches has led to the discovery of extensive and regulated modification of eukaryotic messenger RNAs as well. The two most abundant mRNA modifications-pseudouridine (Ψ) and N(6)-methyladenosine (m(6)A)-affect diverse cellular processes including mRNA splicing, localization, translation, and decay and modulate RNA structure. Here, we test the hypothesis that RNA modifications directly affect interactions between RNA-binding proteins and target RNA. We show that Ψ and m(6)A weaken the binding of the human single-stranded RNA binding protein Pumilio 2 (hPUM2) to its consensus motif, with individual modifications having effects up to approximately threefold and multiple modifications giving larger effects. While there are likely to be some cases where RNA modifications essentially fully ablate protein binding, here we see modest responses that may be more common. Such modest effects could nevertheless profoundly alter the complex landscape of RNA:protein interactions, and the quantitative rather than qualitative nature of these effects underscores the need for quantitative, systems-level accounting of RNA:protein interactions to understand post-transcriptional regulation. © 2017 Vaidyanathan et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  18. Patterns and plasticity in RNA-protein interactions enable recruitment of multiple proteins through a single site

    SciTech Connect

    Valley, Cary T.; Porter, Douglas F.; Qiu, Chen; Campbell, Zachary T.; Tanaka Hall, Traci M.; Wickens, Marvin

    2012-06-28

    mRNA control hinges on the specificity and affinity of proteins for their RNA binding sites. Regulatory proteins must bind their own sites and reject even closely related noncognate sites. In the PUF [Pumilio and fem-3 binding factor (FBF)] family of RNA binding proteins, individual proteins discriminate differences in the length and sequence of binding sites, allowing each PUF to bind a distinct battery of mRNAs. Here, we show that despite these differences, the pattern of RNA interactions is conserved among PUF proteins: the two ends of the PUF protein make critical contacts with the two ends of the RNA sites. Despite this conserved 'two-handed' pattern of recognition, the RNA sequence is flexible. Among the binding sites of yeast Puf4p, RNA sequence dictates the pattern in which RNA bases are flipped away from the binding surface of the protein. Small differences in RNA sequence allow new modes of control, recruiting Puf5p in addition to Puf4p to a single site. This embedded information adds a new layer of biological meaning to the connections between RNA targets and PUF proteins.

  19. Mate choice and the genetic basis for colour variation in a polymorphic dart frog: inferences from a wild pedigree.

    PubMed

    Richards-Zawacki, Corinne L; Wang, Ian J; Summers, Kyle

    2012-08-01

    Understanding how reproductive barriers evolve during speciation remains an important question in evolution. Divergence in mating preferences may be a common first step in this process. The striking colour pattern diversity of strawberry dart frog (Dendrobates pumilio) populations has likely been shaped by sexual selection. Previous laboratory studies have shown that females attend to male coloration and prefer to court with males of their own colour, suggesting that divergent morphs may be reproductively isolated. To test this hypothesis, we used molecular data to estimate pedigree relationships from a polymorphic population. Whereas in the laboratory both red and yellow females preferred to court with males of their own phenotype, our pedigree shows a pattern of assortative mating only for red females. In the wild, yellow females appear to be less choosy about their mates, perhaps because they incur higher costs associated with searching than females of the more common red phenotype. We also used our pedigree to investigate the genetic basis for colour-pattern variation. The phenotype frequencies we observed were consistent with those expected if dorsal background coloration is controlled by a single locus, with complete dominance of red over yellow. Our results not only help clarify the role of sexual selection in reducing gene flow, but also shed light on the mechanisms underlying colour-pattern variation among sympatric colour morphs. The difference we observed between mating preferences measured under laboratory conditions and the pattern of mate choice observed in the wild highlight the importance of field studies for understanding behavioural reproductive isolation.

  20. PolyQ-dependent RNA–protein assemblies control symmetry breaking

    PubMed Central

    Lee, ChangHwan; Occhipinti, Patricia

    2015-01-01

    Dendritic growth in fungi and neurons requires that multiple axes of polarity are established and maintained within the same cytoplasm. We have discovered that transcripts encoding key polarity factors including a formin, Bni1, and a polarisome scaffold, Spa2, are nonrandomly clustered in the cytosol to initiate and maintain sites of polarized growth in the fungus Ashbya gossypii. This asymmetric distribution requires the mRNAs to interact with a polyQ-containing protein, Whi3, and a Pumilio protein with a low-complexity sequence, Puf2. Cells lacking Whi3 or Puf2 had severe defects in establishing new sites of polarity and failed to localize Bni1 protein. Interaction of mRNAs with Whi3 and Puf2 promotes enrichment of transcripts at established sites of polarized growth and clustering of polarity transcripts throughout the cell body. Thus, aggregation-prone proteins make functional assemblies to position polarity transcripts, and nonrandom positioning of transcripts is required for symmetry-breaking events. This reveals a physiological function for polyQ-driven assemblies in regulating cell polarity. PMID:25713414

  1. Poison frog color morphs express assortative mate preferences in allopatry but not sympatry.

    PubMed

    Yang, Yusan; Richards-Zawacki, Corinne L; Devar, Anisha; Dugas, Matthew B

    2016-12-01

    The concurrent divergence of mating traits and preferences is necessary for the evolution of reproductive isolation via sexual selection, and such coevolution has been demonstrated in diverse lineages. However, the extent to which assortative mate preferences are sufficient to drive reproductive isolation in nature is less clear. Natural contact zones between lineages divergent in traits and preferences provide exceptional opportunities for testing the predicted evolutionary consequences of such divergence. The strawberry poison frog (Oophaga pumilio) displays extreme color polymorphism in and around the young Bocas del Toro archipelago. In a transition zone between red and blue allopatric lineages, we asked whether female preferences diverged along with coloration, and whether any divergent preferences persist in a zone of sympatry. When choosing among red, blue and phenotypically intermediate males, females from monomorphic red and monomorphic blue populations both expressed assortative preferences. However, red, blue, and intermediate females from the contact zone all preferred red males, suggesting that divergent preferences may be insufficient to effect behavioral isolation. Our results highlight the complexity of behavioral isolation, and the need for studies that can reveal the circumstances under which divergent preferences do and do not contribute to speciation. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  2. Translational Repression in Malaria Sporozoites

    PubMed Central

    Turque, Oliver; Tsao, Tiffany; Li, Thomas; Zhang, Min

    2016-01-01

    Malaria is a mosquito-borne infectious disease of humans and other animals. It is caused by the parasitic protozoan, Plasmodium. Sporozoites, the infectious form of malaria parasites, are quiescent when they remain in the salivary glands of the Anopheles mosquito until transmission into a mammalian host. Metamorphosis of the dormant sporozoite to its active form in the liver stage requires transcriptional and translational regulations. Here, we summarize recent advances in the translational repression of gene expression in the malaria sporozoite. In sporozoites, many mRNAs that are required for liver stage development are translationally repressed. Phosphorylation of eukaryotic Initiation Factor 2α (eIF2α) leads to a global translational repression in sporozoites. The eIF2α kinase, known as Upregulated in Infectious Sporozoite 1 (UIS1), is dominant in the sporozoite. The eIF2α phosphatase, UIS2, is translationally repressed by the Pumilio protein Puf2. This translational repression is alleviated when sporozoites are delivered into the mammalian host.

  3. Trade-offs between reproduction and health in free-ranging African striped mice.

    PubMed

    Schoepf, I; Pillay, N; Schradin, C

    2017-05-01

    Energy is limited and must be allocated among competing life-history traits. Reproduction is considered one of the most energetically demanding life-history stages. Therefore, the amount of energy an individual invests in reproduction might carry fitness costs through reduced energy allocation to other activities such as health maintenance. We investigated whether reproduction impacts health in the seasonally breeding African striped mouse (Rhabdomys pumilio). We measured health in individuals that reproduced (breeders) and individuals that did not reproduce (their adult offspring) and tested whether: (1) breeders' health before reproduction was similar to that of their offspring (representing a baseline); (2) breeders' health deteriorated after reproduction; (3) breeders' health after reproduction was worse than that of their offspring. We collected blood samples from 12 breeding females and 11 breeding males both at the onset and at the end of the breeding season and from 12 adult daughters and 11 adult sons that did not reproduce at the end of the breeding season. Health was assessed using serum biochemistry analysis with VetScan Abaxis. Breeders differed considerably in their health before and after reproduction, particularly in parameters associated with digestion (lower amylase in males), metabolism (lower albumin, alkaline phosphatase, creatinine and glucose), osmoregulation (lower potassium and phosphorous in females) and immunity (higher globulin and altered alanine aminotransferase). Our results suggest that with the onset of breeding striped mice shifted their energy allocation from maintaining health to reproduction, indicating that investment into reproduction carries significant health costs.

  4. Comparative analysis of reference gene stability in human mesenchymal stromal cells during osteogenic differentiation.

    PubMed

    Jacobi, Angela; Rauh, Juliane; Bernstein, Peter; Liebers, Cornelia; Zou, Xuenong; Stiehler, Maik

    2013-01-01

    Mesenchymal stromal cells (MSCs) are one of the most frequently used cell sources for tissue engineering strategies. Cultivation of osteogenic MSCs is a prerequisite for cell-based concepts that aim at bone regeneration. Quantitative real time reverse transcription polymerase chain reaction (qRT-PCR) analysis is a commonly used method for the examination of mRNA expression levels. However, data on suitable reference genes for osteogenically cultivated MSCs is scarce. Hence, the aim of the study was to compare the regulation of different potential reference genes in osteogenically stimulated MSCs. Human MSCs were isolated from bone marrow aspirates of N = 6 hematologically healthy individuals, expanded by polystyrene-adherence, and maintained with and without osteogenic supplements for 14 days. Cellular proliferation and osteogenic differentiation were assessed by total DNA quantification, cell-specific alkaline phosphatase (ALP) activity and by qualitative staining for ALP and alizarin red, respectively. mRNA expression levels of N = 32 potential reference genes were quantified using the human Endogenous Control TaqMan® assays. mRNA expression stability was calculated using geNorm. The combined use of the most stable reference genes and DNA-damage-inducible alpha, Pumilio homolog 1, and large ribosomal protein P0 significantly improved gene expression accuracy as compared to the use of the commonly used reference genes beta actin and glyceraldehyde-3-phosphate dehydrogenase during qRT-PCR-based target gene expression analysis of osteogenically stimulated MSCs. © 2013 American Institute of Chemical Engineers.

  5. Cooperative breeding in groups of synchronously mating females and evolution of large testes to avoid sperm depletion in african striped mice.

    PubMed

    Schradin, C; Kinahan, A A; Pillay, N

    2009-07-01

    Testis size has been related to the mating system of both vertebrates and invertebrates. These differences are regarded as adaptive responses to sperm competition in promiscuously mating species. However, not all variation in testis size can be explained by sperm competition. Here, we test the hypothesis that the evolution of large testes occurs when synchronously breeding females must be fertilized within a short period of time to avoid reproductive competition among the females. African striped mouse (Rhabdomys pumilio) males of a polygynous population with cooperative breeding and high risk of sperm depletion had testes and cauda epididymis twice as large as those of males of four different promiscuous populations with high risk of sperm competition. When paired with three females simultaneously in captivity, males of the polygynous population bred with three females within 8 days, leading to synchronous births in their harems, thereby potentially reducing the risk of infanticide. Males from the promiscuous population reproduced with only one or two females within 8 days, and births were not synchronous. We conclude that large testes are selected for in species with synchronously mating females, which is ultimately beneficial for the evolution of cooperative breeding.

  6. Perturbations of Plasmodium Puf2 Expression and RNA-seq of Puf2-Deficient Sporozoites Reveal a Critical Role in Maintaining RNA Homeostasis and Parasite Transmissibility

    PubMed Central

    Lindner, Scott E.; Mikolajczak, Sebastian A.; Vaughan, Ashley M.; Moon, Wonjong; Joyce, Brad R.; Sullivan, William J.; Kappe, Stefan H. I.

    2013-01-01

    Summary Malaria's cycle of infection requires parasite transmission between a mosquito vector and a mammalian host. We here demonstrate that the Plasmodium yoelii Pumilio-FBF family member Puf2 allows the sporozoite to remain infectious in the mosquito salivary glands while awaiting transmission. Puf2 mediates this solely through its RNA-Binding Domain (RBD) likely by stabilizing or hastening the degradation of specific mRNAs. Puf2 traffics to sporozoite cytosolic granules, which are negative for several markers of stress granules and P-bodies, and disappear rapidly after infection of hepatocytes. In contrast to previously described Plasmodium berghei pbpuf2− parasites, pypuf2− sporozoites have no apparent defect in host infection when tested early in salivary gland residence, but become progressively noninfectious and prematurely transform into EEFs during prolonged salivary gland residence. The premature overexpression of Puf2 in oocysts causes striking deregulation of sporozoite maturation and infectivity while extension of Puf2 expression in liver stages causes no defect, suggesting that the presence of Puf2 alone is not sufficient for its functions. Finally, by conducting the first comparative RNA-seq analysis of Plasmodium sporozoites, we find that Puf2 may play a role in directly or indirectly maintaining the homeostasis of specific transcripts. These findings uncover requirements for maintaining a window of opportunity for the malaria parasite to accommodate the unpredictable moment of transmission from mosquito to mammalian host. PMID:23356439

  7. REDUCED DORMANCY5 Encodes a Protein Phosphatase 2C That Is Required for Seed Dormancy in Arabidopsis[C][W][OPEN

    PubMed Central

    Xiang, Yong; Nakabayashi, Kazumi; Ding, Jia; He, Fei; Bentsink, Leónie; Soppe, Wim J.J.

    2014-01-01

    Seed dormancy determines germination timing and contributes to crop production and the adaptation of natural populations to their environment. Our knowledge about its regulation is limited. In a mutagenesis screen of a highly dormant Arabidopsis thaliana line, the reduced dormancy5 (rdo5) mutant was isolated based on its strongly reduced seed dormancy. Cloning of RDO5 showed that it encodes a PP2C phosphatase. Several PP2C phosphatases belonging to clade A are involved in abscisic acid signaling and control seed dormancy. However, RDO5 does not cluster with clade A phosphatases, and abscisic acid levels and sensitivity are unaltered in the rdo5 mutant. RDO5 transcript could only be detected in seeds and was most abundant in dry seeds. RDO5 was found in cells throughout the embryo and is located in the nucleus. A transcriptome analysis revealed that several genes belonging to the conserved PUF family of RNA binding proteins, in particular Arabidopsis PUMILIO9 (APUM9) and APUM11, showed strongly enhanced transcript levels in rdo5 during seed imbibition. Further transgenic analyses indicated that APUM9 reduces seed dormancy. Interestingly, reduction of APUM transcripts by RNA interference complemented the reduced dormancy phenotype of rdo5, indicating that RDO5 functions by suppressing APUM transcript levels. PMID:25415980

  8. A multitasking Argonaute: exploring the many facets of C. elegans CSR-1.

    PubMed

    Wedeles, Christopher J; Wu, Monica Z; Claycomb, Julie M

    2013-12-01

    While initial studies of small RNA-mediated gene regulatory pathways focused on the cytoplasmic functions of such pathways, identifying roles for Argonaute/small RNA pathways in modulating chromatin and organizing the genome has become a topic of intense research in recent years. Nuclear regulatory mechanisms for Argonaute/small RNA pathways appear to be widespread, in organisms ranging from plants to fission yeast, Caenorhabditis elegans to humans. As the effectors of small RNA-mediated gene regulatory pathways, Argonaute proteins guide the chromatin-directed activities of these pathways. Of particular interest is the C. elegans Argonaute, chromosome segregation and RNAi deficient (CSR-1), which has been implicated in such diverse functions as organizing the holocentromeres of worm chromosomes, modulating germline chromatin, protecting the genome from foreign nucleic acid, regulating histone levels, executing RNAi, and inhibiting translation in conjunction with Pumilio proteins. CSR-1 interacts with small RNAs known as 22G-RNAs, which have complementarity to 25 % of the protein coding genes. This peculiar Argonaute is the only essential C. elegans Argonaute out of 24 family members in total. Here, we summarize the current understanding of CSR-1 functions in the worm, with emphasis on the chromatin-directed activities of this ever-intriguing Argonaute.

  9. Cryptic female Strawberry poison frogs experience elevated predation risk when associating with an aposematic partner.

    PubMed

    Segami Marzal, Julia Carolina; Rudh, Andreas; Rogell, Björn; Ödeen, Anders; Løvlie, Hanne; Rosher, Charlotte; Qvarnström, Anna

    2017-01-01

    Population divergence in sexual signals may lead to speciation through prezygotic isolation. Sexual signals can change solely due to variation in the level of natural selection acting against conspicuousness. However, directional mate choice (i.e., favoring conspicuousness) across different environments may lead to gene flow between populations, thereby delaying or even preventing the evolution of reproductive barriers and speciation. In this study, we test whether natural selection through predation upon mate-choosing females can favor corresponding changes in mate preferences. Our study system, Oophaga pumilio, is an extremely color polymorphic neotropical frog with two distinctive antipredator strategies: aposematism and crypsis. The conspicuous coloration and calling behavior of aposematic males may attract both cryptic and aposematic females, but predation may select against cryptic females choosing aposematic males. We used an experimental approach where domestic fowl were encouraged to find digitized images of cryptic frogs at different distances from aposematic partners. We found that the estimated survival time of a cryptic frog was reduced when associating with an aposematic partner. Hence, predation may act as a direct selective force on female choice, favoring evolution of color assortative mating that, in turn, may strengthen the divergence in coloration that natural selection has generated.

  10. Fragment-based modelling of single stranded RNA bound to RNA recognition motif containing proteins

    PubMed Central

    de Beauchene, Isaure Chauvot; de Vries, Sjoerd J.; Zacharias, Martin

    2016-01-01

    Protein-RNA complexes are important for many biological processes. However, structural modeling of such complexes is hampered by the high flexibility of RNA. Particularly challenging is the docking of single-stranded RNA (ssRNA). We have developed a fragment-based approach to model the structure of ssRNA bound to a protein, based on only the protein structure, the RNA sequence and conserved contacts. The conformational diversity of each RNA fragment is sampled by an exhaustive library of trinucleotides extracted from all known experimental protein–RNA complexes. The method was applied to ssRNA with up to 12 nucleotides which bind to dimers of the RNA recognition motifs (RRMs), a highly abundant eukaryotic RNA-binding domain. The fragment based docking allows a precise de novo atomic modeling of protein-bound ssRNA chains. On a benchmark of seven experimental ssRNA–RRM complexes, near-native models (with a mean heavy-atom deviation of <3 Å from experiment) were generated for six out of seven bound RNA chains, and even more precise models (deviation < 2 Å) were obtained for five out of seven cases, a significant improvement compared to the state of the art. The method is not restricted to RRMs but was also successfully applied to Pumilio RNA binding proteins. PMID:27131381

  11. Conserved regulation of MAP kinase expression by PUF RNA-binding proteins.

    PubMed

    Lee, Myon-Hee; Hook, Brad; Pan, Guangjin; Kershner, Aaron M; Merritt, Christopher; Seydoux, Geraldine; Thomson, James A; Wickens, Marvin; Kimble, Judith

    2007-12-28

    Mitogen-activated protein kinase (MAPK) and PUF (for Pumilio and FBF [fem-3 binding factor]) RNA-binding proteins control many cellular processes critical for animal development and tissue homeostasis. In the present work, we report that PUF proteins act directly on MAPK/ERK-encoding mRNAs to downregulate their expression in both the Caenorhabditis elegans germline and human embryonic stem cells. In C. elegans, FBF/PUF binds regulatory elements in the mpk-1 3' untranslated region (3' UTR) and coprecipitates with mpk-1 mRNA; moreover, mpk-1 expression increases dramatically in FBF mutants. In human embryonic stem cells, PUM2/PUF binds 3'UTR elements in both Erk2 and p38alpha mRNAs, and PUM2 represses reporter constructs carrying either Erk2 or p38alpha 3' UTRs. Therefore, the PUF control of MAPK expression is conserved. Its biological function was explored in nematodes, where FBF promotes the self-renewal of germline stem cells, and MPK-1 promotes oocyte maturation and germ cell apoptosis. We found that FBF acts redundantly with LIP-1, the C. elegans homolog of MAPK phosphatase (MKP), to restrict MAPK activity and prevent apoptosis. In mammals, activated MAPK can promote apoptosis of cancer cells and restrict stem cell self-renewal, and MKP is upregulated in cancer cells. We propose that the dual negative regulation of MAPK by both PUF repression and MKP inhibition may be a conserved mechanism that influences both stem cell maintenance and tumor progression.

  12. MPK-1/ERK regulatory network controls the number of sperm by regulating timing of sperm-oocyte switch in C. elegans germline.

    PubMed

    Yoon, Dong Suk; Alfhili, Mohammad A; Friend, Kyle; Lee, Myon-Hee

    2017-09-30

    The precise regulation of germline sexual fate is crucial for animal fertility. In C. elegans, the production of either type of gamete, sperm or oocyte, becomes mutually exclusive beyond the larval stage. Hermaphrodites initially produce sperm and then switch to produce oocytes. This change of fate during germline development is tightly controlled by several regulators. In C. elegans hermaphrodites, FBF-1 and FBF-2 (>95% identical, members of the Pumilio RNA-binding protein family) proteins function redundantly to promote the sperm-oocyte switch. Here, we demonstrate that loss of LIP-1 (dual specificity phosphatase) in fbf-1(ok91) single mutants leads to excess sperm production due to a delayed sperm-oocyte switch. This phenotype was dramatically rescued by depletion of MPK-1 (an ERK homolog). In contrast, loss of LIP-1 in fbf-2(q738) single mutants leads to a premature sperm-oocyte switch and loss of sperm. Notably, fbf-1 fbf-2; lip-1 triple mutants produce excess sperm. These results suggest that the MPK-1/ERK regulatory network, including FBF-1, FBF-2, and LIP-1, controls the number of sperm by regulating the timing of the sperm-oocyte switch in C. elegans. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. SimiRa: A tool to identify coregulation between microRNAs and RNA-binding proteins

    PubMed Central

    Preusse, Martin; Marr, Carsten; Saunders, Sita; Maticzka, Daniel; Lickert, Heiko; Backofen, Rolf; Theis, Fabian

    2015-01-01

    microRNAs and microRNA-independent RNA-binding proteins are 2 classes of post-transcriptional regulators that have been shown to cooperate in gene-expression regulation. We compared the genome-wide target sets of microRNAs and RBPs identified by recent CLIP-Seq technologies, finding that RBPs have distinct target sets and favor gene interaction network hubs. To identify microRNAs and RBPs with a similar functional context, we developed simiRa, a tool that compares enriched functional categories such as pathways and GO terms. We applied simiRa to the known functional cooperation between Pumilio family proteins and miR-221/222 in the regulation of tumor supressor gene p27 and show that the cooperation is reflected by similar enriched categories but not by target genes. SimiRa also predicts possible cooperation of microRNAs and RBPs beyond direct interaction on the target mRNA for the nuclear RBP TAF15. To further facilitate research into cooperation of microRNAs and RBPs, we made simiRa available as a web tool that displays the functional neighborhood and similarity of microRNAs and RBPs: http://vsicb-simira.helmholtz-muenchen.de. PMID:26383775

  14. Futile attempts to differentiate provide molecular evidence for individual differences within a population of cells during cellular reprogramming.

    PubMed

    Hoffmann, Xenia-Katharina; Tesmer, Jens; Souquet, Manfred; Marwan, Wolfgang

    2012-04-01

    The heterogeneity of cell populations and the influence of stochastic noise might be important issues for the molecular analysis of cellular reprogramming at the system level. Here, we show that in Physarum polycephalum, the expression patterns of marker genes correlate with the fate decision of individual multinucleate plasmodial cells that had been exposed to a differentiation-inducing photostimulus. For several hours after stimulation, the expression kinetics of PI-3-kinase, piwi, and pumilio orthologs and other marker genes were qualitatively similar in all stimulated cells but quantitatively different in those cells that subsequently maintained their proliferative potential and failed to differentiate accordingly. The results suggest that the population of nuclei in an individual plasmodium behaves synchronously in terms of gene regulation to an extent that the plasmodium provides a source for macroscopic amounts of homogeneous single-cell material for analysing the dynamic processes of cellular reprogramming. Based on the experimental findings, we predict that circuits with switch-like behaviour that control the cell fate decision of a multinucleate plasmodium operate through continuous changes in the concentration of cellular regulators because the nuclear population suspended in a large cytoplasmic volume damps stochastic noise.

  15. PINK1 and Parkin control localized translation of respiratory chain component mRNAs on mitochondria outer membrane.

    PubMed

    Gehrke, Stephan; Wu, Zhihao; Klinkenberg, Michael; Sun, Yaping; Auburger, Georg; Guo, Su; Lu, Bingwei

    2015-01-06

    Mitochondria play essential roles in many aspects of biology, and their dysfunction has been linked to diverse diseases. Central to mitochondrial function is oxidative phosphorylation (OXPHOS), accomplished by respiratory chain complexes (RCCs) encoded by nuclear and mitochondrial genomes. How RCC biogenesis is regulated in metazoans is poorly understood. Here we show that Parkinson's disease (PD)-associated genes PINK1 and Parkin direct localized translation of certain nuclear-encoded RCC (nRCC) mRNAs. Translationally repressed nRCC mRNAs are localized in a PINK1/Tom20-dependent manner to mitochondrial outer membrane, where they are derepressed and activated by PINK1/Parkin through displacement of translation repressors, including Pumilio and Glorund/hnRNP-F, a Parkin substrate, and enhanced binding of activators such as eIF4G. Inhibiting the translation repressors rescued nRCC mRNA translation and neuromuscular-degeneration phenotypes of PINK1 mutant, whereas inhibiting eIF4G had opposite effects. Our results reveal previously unknown functions of PINK1/Parkin in RNA metabolism and suggest new approaches to mitochondrial restoration and disease intervention.

  16. Role for RNA-Binding Proteins Implicated in Pathogenic Development of Ustilago maydis†

    PubMed Central

    Becht, Philip; Vollmeister, Evelyn; Feldbrügge, Michael

    2005-01-01

    Ustilago maydis causes smut disease on corn. Successful infection depends on a number of morphological transitions, such as pheromone-dependent formation of conjugation tubes and the switch to filamentous dikaryotic growth, as well as different types of mycelial structures during growth within the host plant. In order to address the involvement of RNA-binding proteins during this developmental program, we identified 27 open reading frames from the genome sequence encoding potential RNA-binding proteins. They exhibit similarities to RNA-binding proteins with Pumilio homology domains (PUM), the K homology domain (KHD), the double-stranded RNA binding motif (DSRM), and the RNA recognition motif (RRM). For 18 of these genes, we generated replacement mutants in compatible haploid strains. Through analysis of growth behavior, morphology, cyclic AMP response, mating, and pathogenicity, we identified three candidates with aberrant phenotypes. Loss of Khd1, a K homology protein containing three KHDs, resulted in a cold-sensitive growth phenotype. Deletion of khd4 encoding a protein with five KHDs led to abnormal cell morphology, reduced mating, and virulence. rrm4Δ strains were affected in filamentous growth and pathogenicity. Rrm4 is an RRM protein with a so far unique domain organization consisting of three N-terminal RRMs as well as a domain found in the C terminus of poly(A)-binding proteins. These results indicate a role for RNA-binding proteins in regulation of morphology as well as in pathogenic development in U. maydis. PMID:15643068

  17. Posterior elongation in the annelid Platynereis dumerilii involves stem cells molecularly related to primordial germ cells.

    PubMed

    Gazave, Eve; Béhague, Julien; Laplane, Lucie; Guillou, Aurélien; Préau, Laetitia; Demilly, Adrien; Balavoine, Guillaume; Vervoort, Michel

    2013-10-01

    Like most bilaterian animals, the annelid Platynereis dumerilii generates the majority of its body axis in an anterior to posterior temporal progression with new segments added sequentially. This process relies on a posterior subterminal proliferative body region, known as the "segment addition zone" (SAZ). We explored some of the molecular and cellular aspects of posterior elongation in Platynereis, in particular to test the hypothesis that the SAZ contains a specific set of stem cells dedicated to posterior elongation. We cloned and characterized the developmental expression patterns of orthologs of 17 genes known to be involved in the formation, behavior, or maintenance of stem cells in other metazoan models. These genes encode RNA-binding proteins (e.g., tudor, musashi, pumilio) or transcription factors (e.g., myc, id, runx) widely conserved in eumetazoans. Most of these genes are expressed both in the migrating primordial germ cells and in overlapping ring-like patterns in the SAZ, similar to some previously analyzed genes (piwi, vasa). The SAZ patterns are coincident with the expression of proliferation markers cyclin B and PCNA. EdU pulse and chase experiments suggest that new segments are produced through many rounds of divisions from small populations of teloblast-like posterior stem cells. The shared molecular signature between primordial germ cells and posterior stem cells in Platynereis thus corresponds to an ancestral "stemness" program. © 2013 Elsevier Inc. All rights reserved.

  18. Climate-Induced Range Shifts and Possible Hybridisation Consequences in Insects

    PubMed Central

    Sánchez-Guillén, Rosa Ana; Muñoz, Jesús; Rodríguez-Tapia, Gerardo; Feria Arroyo, T. Patricia; Córdoba-Aguilar, Alex

    2013-01-01

    Many ectotherms have altered their geographic ranges in response to rising global temperatures. Current range shifts will likely increase the sympatry and hybridisation between recently diverged species. Here we predict future sympatric distributions and risk of hybridisation in seven Mediterranean ischnurid damselfly species (I. elegans, I. fountaineae, I. genei, I. graellsii, I. pumilio, I. saharensis and I. senegalensis). We used a maximum entropy modelling technique to predict future potential distribution under four different Global Circulation Models and a realistic emissions scenario of climate change. We carried out a comprehensive data compilation of reproductive isolation (habitat, temporal, sexual, mechanical and gametic) between the seven studied species. Combining the potential distribution and data of reproductive isolation at different instances (habitat, temporal, sexual, mechanical and gametic), we infer the risk of hybridisation in these insects. Our findings showed that all but I. graellsii will decrease in distributional extent and all species except I. senegalensis are predicted to have northern range shifts. Models of potential distribution predicted an increase of the likely overlapping ranges for 12 species combinations, out of a total of 42 combinations, 10 of which currently overlap. Moreover, the lack of complete reproductive isolation and the patterns of hybridisation detected between closely related ischnurids, could lead to local extinctions of native species if the hybrids or the introgressed colonising species become more successful. PMID:24260411

  19. An essential role of KREPB4 in RNA editing and structural integrity of the editosome in Trypanosoma brucei

    PubMed Central

    Babbarwal, Vinod Kumar; Fleck, Michele; Ernst, Nancy Lewis; Schnaufer, Achim; Stuart, Kenneth

    2007-01-01

    RNA editing in the sleeping sickness parasite Trypanosoma brucei remodels mitochondrial transcripts by the addition and deletion of uridylates as specified by guide RNAs. Editing is catalyzed by at least three distinct ∼20S multiprotein editosomes, all of which contain KREPB4, a protein with RNase III and Pumilio motifs. RNAi repression of KREPB4 expression in procyclic forms (PFs) strongly inhibited growth and in vivo RNA editing, greatly diminished the abundance of 20S editosomes, reduced cellular levels of editosome proteins, and generated ∼5–10S editosome subcomplexes. Editing TUTase, exoUase, and RNA ligase activities were largely shifted from ∼20S to ∼5–10S fractions of cellular lysates. Insertion and deletion endonuclease activities in ∼20S fractions were strongly reduced upon KREPB4 repression but were not detected in the 5–10S subcomplex fraction. Abundance of MRP1 and RBP16 proteins, which appear to be involved in RNA processing but are not components of the 20S editosome, was unaltered upon KREPB4 repression. These data suggest that KREPB4 is important for the structural integrity of ∼20S editosomes, editing endonuclease activity, and the viability of PF T. brucei cells. PMID:17369311

  20. Recurrent rewiring and emergence of RNA regulatory networks.

    PubMed

    Wilinski, Daniel; Buter, Natascha; Klocko, Andrew D; Lapointe, Christopher P; Selker, Eric U; Gasch, Audrey P; Wickens, Marvin

    2017-04-04

    Alterations in regulatory networks contribute to evolutionary change. Transcriptional networks are reconfigured by changes in the binding specificity of transcription factors and their cognate sites. The evolution of RNA-protein regulatory networks is far less understood. The PUF (Pumilio and FBF) family of RNA regulatory proteins controls the translation, stability, and movements of hundreds of mRNAs in a single species. We probe the evolution of PUF-RNA networks by direct identification of the mRNAs bound to PUF proteins in budding and filamentous fungi and by computational analyses of orthologous RNAs from 62 fungal species. Our findings reveal that PUF proteins gain and lose mRNAs with related and emergent biological functions during evolution. We demonstrate at least two independent rewiring events for PUF3 orthologs, independent but convergent evolution of PUF4/5 binding specificity and the rewiring of the PUF4/5 regulons in different fungal lineages. These findings demonstrate plasticity in RNA regulatory networks and suggest ways in which their rewiring occurs.

  1. Transient translational quiescence in primordial germ cells.

    PubMed

    Oulhen, Nathalie; Swartz, S Zachary; Laird, Jessica; Mascaro, Alexandra; Wessel, Gary

    2017-02-24

    Stem cells in animals often exhibit a slow cell cycle and/or low transcriptional activity referred to as quiescence. Here we report that the translational activity in the primordial germ cells (PGCs) of the sea urchin embryo (Strongylocentrotus purpuratus) is quiescent. We measured new protein synthesis with O-propargyl-puromycin, and L-homopropargylglycine, Click-iT technologies and determined that these cells synthesize protein at only 6% the level of their adjacent somatic cells. Knock-down of translation of the RNA-binding protein Nanos2 by morpholino anti-sense oligonucleotides, or knock-out of the Nanos2 gene by CRISPR/Cas9 resulted in a significant, but partial increase (47%) in general translation specifically in the PGCs. We found that the mRNA of the translation factor eEF1A is excluded from the PGCs in a Nanos2-dependent manner, a consequence of a Nanos/Pumilio response element (PRE) in its 3'UTR. In addition to eEF1A, the cytoplasmic pH of the PGCs appears to repress translation and simply increasing the pH also significantly restores translation selectively in the PGCs. We conclude that the PGCs of this sea urchin institute parallel pathways to quiesce translation thoroughly but transiently.

  2. Reduced Dormancy5 encodes a protein phosphatase 2C that is required for seed dormancy in Arabidopsis.

    PubMed

    Xiang, Yong; Nakabayashi, Kazumi; Ding, Jia; He, Fei; Bentsink, Leónie; Soppe, Wim J J

    2014-11-01

    Seed dormancy determines germination timing and contributes to crop production and the adaptation of natural populations to their environment. Our knowledge about its regulation is limited. In a mutagenesis screen of a highly dormant Arabidopsis thaliana line, the reduced dormancy5 (rdo5) mutant was isolated based on its strongly reduced seed dormancy. Cloning of RDO5 showed that it encodes a PP2C phosphatase. Several PP2C phosphatases belonging to clade A are involved in abscisic acid signaling and control seed dormancy. However, RDO5 does not cluster with clade A phosphatases, and abscisic acid levels and sensitivity are unaltered in the rdo5 mutant. RDO5 transcript could only be detected in seeds and was most abundant in dry seeds. RDO5 was found in cells throughout the embryo and is located in the nucleus. A transcriptome analysis revealed that several genes belonging to the conserved PUF family of RNA binding proteins, in particular Arabidopsis PUMILIO9 (APUM9) and APUM11, showed strongly enhanced transcript levels in rdo5 during seed imbibition. Further transgenic analyses indicated that APUM9 reduces seed dormancy. Interestingly, reduction of APUM transcripts by RNA interference complemented the reduced dormancy phenotype of rdo5, indicating that RDO5 functions by suppressing APUM transcript levels. © 2014 American Society of Plant Biologists. All rights reserved.

  3. Viremia and antibody response of small African and laboratory animals to Crimean-Congo hemorrhagic fever virus infection.

    PubMed

    Shepherd, A J; Leman, P A; Swanepoel, R

    1989-05-01

    Eleven species of small African wild mammals, laboratory rabbits, guinea pigs, and Syrian hamsters were infected with Crimean-Congo hemorrhagic fever (CCHF) virus. Low-titered viremia followed by development of antibody was observed in scrub hares (Lepus saxatilis), Cape ground squirrels (Xerus inauris), red veld rats (Aethomys chrysophilus), white tailed rats (Mystromys albicaudatus), bushveld gerbils (Tatera leucogaster), striped mice (Rhabdomys pumilio), and guinea pigs. The maximum viremic titer in 4 scrub hares was 10(1.7-4.2) 50% mouse lethal doses/ml. Viremia was detected in 1/17 infected laboratory rabbits. Antibody response was only detected in South African hedgehogs (Atelerix frontalis), highveld gerbils (T. brantsii), Namaqua gerbils (Desmodillus auricularis), 2 species of multimammate mouse (Mastomys natalensis and M. coucha), and Syrian hamsters. The results of the study indicate that a proportion of infected scrub hares develop CCHF viremia of an intensity shown in the Soviet Union to be sufficient for infection of feeding immature ixodid ticks, but that South African hedgehogs and wild rodents are unlikely to be of importance as maintenance hosts of the virus in southern Africa.

  4. Annotated type catalogue of the Orthalicoidea (Mollusca, Gastropoda) in the Museum für Naturkunde, Berlin

    PubMed Central

    Breure, Abraham S.H.

    2013-01-01

    Abstract The type status is described of 96 taxa classified within the superfamily Orthalicoidea and present in the Mollusca collection of the Museum für Naturkunde der Humboldt-Universität zu Berlin. Lectotypes are designated for the following taxa: Orthalicus elegans Rolle, 1895; Bulimus maranhonensis Albers, 1854; Orthalicus nobilis Rolle, 1895; Orthalichus tricinctus Martens, 1893. Orthalicus sphinx tresmariae is introduced as new name for Zebra sphinx turrita Strebel, 1909, not Zebra quagga turrita Strebel, 1909. The following synonyms are established: Zebra crosseifischeri Strebel, 1909 = Orthalicus princeps fischeri Martens, 1893; Orthalicus isabellinus Martens, 1873 = Orthalicus bensoni (Reeve, 1849); Zebra zoniferus naesiotes Strebel, 1909 = Orthalicus undatus (Bruguière, 1789); Porphyrobaphe (Myiorthalicus) dennisoni pallida Strebel, 1909 = Hemibulimus dennisoni (Reeve, 1848); Zebra delphinus pumilio Strebel, 1909 = Orthalicus delphinus (Strebel, 1909); Orthalicus (Laeorthalicus) reginaeformis Strebel, 1909 = Corona perversa (Swainson, 1821); Bulimus (Eurytus) corticosus Sowerby III, 1895 = Plekocheilus (Eurytus) stuebeli Martens, 1885. The taxon Bulimus (Eudioptus) psidii Martens, 1877 is now placed within the family Sagdidae, tentatively in the genus Platysuccinea. Appendices are included with an index to all the types of Orthalicoidea extant (including those listed by Köhler 2007) and a partial list of letters present in the correspondence archives. PMID:23794831

  5. Evaluation of a push-pull strategy for the management of Frankliniella bispinosa (Thysanoptera: Thripidae) in bell peppers.

    PubMed

    Tyler-Julian, Kara; Funderburk, Joe; Frantz, Galen; Mellinger, Charles

    2014-10-01

    A push-pull strategy for managing the anthophilous Frankliniella bispinosa (Morgan) in pepper and increasing conservation biological control was evaluated. Push components of ultraviolet (UV)-reflective mulch and foliar applications of kaolin and the pull component of sunflower companion plants were evaluated in replicated field experiments in 2011 and 2012. Adult F. bispinosa rapidly colonized and reproduced in the peppers and sunflowers during early flowering, but populations declined later, as numbers of the predatory Orius insidiosus (Say) and Orius pumilio (Champion) increased in both hosts. Numbers of F. bispinosa were reduced by kaolin during early pepper flowering. Thrips numbers were increased on some of the later sample dates, apparently due to reduced predation that resulted from negative effects of kaolin and UV-reflective mulch on Orius populations. Numbers of thrips increased in peppers with companion plants during the first week of flowering each year, followed by declines in thrips numbers during the next 2 wk in 2011. There was little effect each year of the companion plants on the numbers of Orius in the pepper flowers. There was one date in 2011 and no dates in 2012 in which UV-reflective mulch or kaolin acted in concert with the presence of the companion plants to reduce thrips numbers in the main crop of pepper. Yield effects were not attributed to thrips damage. We conclude that sunflower companion plants did not act additively or synergistically with kaolin or UV-reflective mulch to reduce thrips and increase Orius populations in pepper.

  6. A conserved PUF/Ago/eEF1A complex attenuates translation elongation

    PubMed Central

    Friend, Kyle; Campbell, Zachary T.; Cooke, Amy; Kroll-Conner, Peggy; Wickens, Marvin P.; Kimble, Judith

    2011-01-01

    SUMMARY PUF (Pumilio/FBF) RNA-binding proteins and Argonaute (Ago) miRNA-binding proteins regulate mRNAs post-transcriptionally, each acting through similar yet distinct mechanisms. Here, we report that PUF and Ago proteins can also function together in a complex with a core translation elongation factor, eEF1A, to repress translation elongation. Both nematode and mammalian PUF/Ago/eEF1A complexes were identified, using co-immunoprecipitation and recombinant protein assays. Nematode CSR-1 (Ago) promotes repression of FBF (PUF) target mRNAs in in vivo assays, and the FBF-1/CSR-1 heterodimer inhibits EFT-3 (eEF1A) GTPase activity in vitro. Mammalian PUM2/Ago/eEF1A inhibits translation of nonadenylated and polyadenylated reporter mRNAs in vitro. This repression occurs after translation initiation and leads to ribosome accumulation within the open reading frame, roughly at the site where the nascent polypeptide emerges from the ribosomal exit tunnel. Together, these data suggest that a conserved PUF/Ago/eEF1A complex attenuates translation elongation. PMID:22231398

  7. Clonorchis sinensis and Opisthorchis spp. in Vietnam: current status and prospects.

    PubMed

    Doanh, Pham N; Nawa, Yukifumi

    2016-01-01

    Clonorchis sinensis and Opisthorchis viverrini are clinically important small liver flukes because of their known association with development of cholangiocarcinoma. In Vietnam, high prevalence of C. sinensis infection in humans was previously reported in northern provinces, and O. viverrini infection has been detected in several central provinces. However, diagnosis of C. sinensis and O. viverrini infections in the past was merely based on faecal egg examination. This method alone can lead to misidentification at the species level because of morphological similarity between the eggs of these liver flukes and minute intestinal trematodes of the family Heterophyidae. In fact, recent surveys in Vietnam revealed that infection with several minute intestinal flukes, such as Haplorchis pumilio and H. taichui, are much more common than infection with C. sinensis or O. viverrini, and they often co-infect humans. Thus, previously reported prevalence of small liver fluke infection in Vietnam was likely over-estimated due to mis identification of parasites in copro-parasitological examinations. In addition, there is some confusion about identification of cercariae, metacercariae and also adults of C. sinensis and O. viverrini in intermediate and definitive hosts. The aim of this review is, therefore, to draw realistic pictures of the past and present scientific reports on the epidemiology and biology of C. sinensis and Opisthorchis spp. infection in Vietnam.

  8. Virtual Screening of Plant Volatile Compounds Reveals a High Affinity of Hylamorpha elegans (Coleoptera: Scarabaeidae) Odorant-Binding Proteins for Sesquiterpenes From Its Native Host

    PubMed Central

    Palma-Millanao, Rubén; Yáñez, Osvaldo; Rojas, Maximiliano; Mutis, Ana; Venthur, Herbert; Quiroz, Andrés; Ramírez, Claudio C.

    2016-01-01

    Hylamorpha elegans (Burmeister) is a native Chilean scarab beetle considered to be a relevant agricultural pest to pasture and cereal and small fruit crops. Because of their cryptic habits, control with conventional methods is difficult; therefore, alternative and environmentally friendly control strategies are highly desirable. The study of proteins that participate in the recognition of odorants, such as odorant-binding proteins (OBPs), offers interesting opportunities to identify new compounds with the potential to modify pest behavior and computational screening of compounds, which is commonly used in drug discovery, may help to accelerate the discovery of new semiochemicals. Here, we report the discovery of four OBPs in H. elegans as well as six new volatiles released by its native host Nothofagus obliqua (Mirbel). Molecular docking performed between OBPs and new and previously reported volatiles from N. obliqua revealed the best binding energy values for sesquiterpenic compounds. Despite remarkable divergence at the amino acid level, three of the four OBPs evaluated exhibited the best interaction energy for the same ligands. Molecular dynamics investigation reinforced the importance of sesquiterpenes, showing that hydrophobic residues of the OBPs interacted most frequently with the tested ligands, and binding free energy calculations demonstrated van der Waals and hydrophobic interactions to be the most important. Altogether, the results suggest that sesquiterpenes are interesting candidates for in vitro and in vivo assays to assess their potential application in pest management strategies. PMID:27012867

  9. The spatial distribution of acid phosphatase activity in ectomycorrhizal tissues depends on soil fertility and morphotype, and relates to host plant phosphorus uptake.

    PubMed

    Alvarez, Maricel; Huygens, Dries; Díaz, Leila Milena; Villanueva, Claudia Añazco; Heyser, Wolfgang; Boeckx, Pascal

    2012-01-01

    Acid phosphatase (ACP) enzymes are involved in the mobilization of soil phosphorus (P) and polyphosphate accumulated in the fungal tissues of ectomycorrhizal roots, thereby influencing the amounts of P that are stored in the fungus and transferred to the host plant. This study evaluated the effects of ectomycorrhizal morphotype and soil fertility on ACP activity in the extraradical mycelium (ACP(myc)), the mantle (ACP(mantle)) and the Hartig net region (ACP(Hartig)) of ectomycorrhizal Nothofagus obliqua seedlings. ACP activity was quantified in vivo using enzyme-labelled fluorescence-97 (ELF-97) substrate, confocal laser microscopy and digital image processing routines. There was a significant effect of ectomycorrhizal morphotype on ACP(myc), ACP(mantle) and ACP(Hartig), while soil fertility had a significant effect on ACP(myc) and ACP(Hartig). The relative contribution of the mantle and the Hartig net region to the ACP activity on the ectomycorrhizal root was significantly affected by ectomycorrhizal morphotype and soil fertility. A positive correlation between ACP(Hartig) and the shoot P concentration was found, providing evidence that ACP activity at the fungus:root interface is involved in P transfer from the fungus to the host. It is concluded that the spatial distribution of ACP in ectomycorrhizas varies as a function of soil fertility and colonizing fungus.

  10. Two new Liolaemus lizards from the Andean highlands of Southern Chile (Squamata, Iguania, Liolaemidae).

    PubMed

    Troncoso-Palacios, Jaime; Diaz, Hugo A; Puas, German I; Riveros-Riffo, Edvin; Elorza, Alvaro A

    2016-01-01

    Liolaemus is a diverse genus of lizards, subdivided into two subgenera: Liolaemus (sensu stricto) and Eulaemus, distributed mainly in Chile and Argentina. The Liolaemus elongatus-kriegi complex is the most diverse group within Liolaemus (sensu stricto), especially the species closely related to Liolaemus elongatus, which form a clade currently comprising nine species. Several Chilean species of this group have been recently described, mainly from volcanoes and poorly explored mountains. Here molecular and morphological evidence are provided for a new species of the Liolaemus elongatus clade, which is characterized by its small size and lack of dorsal pattern, unusual features for the species of this group of lizards. Additionally, the lack of precloacal pores in males of Liolaemus (sensu stricto) is a trait found in few species, which do not constitute a monophyletic group. A second new southern Chilean species is also described, without precloacal pores and supported by molecular phylogenetics to be related to Liolaemus villaricensis. Both new species were found in the same locality, near a lake located in a pre-Andean zone with Araucaria and Nothofagus forest. The two species are dedicated to prominent Lonkos (tribal chiefs) of the Mapuche and Pehuenche people: Janequeo and Leftraru. Additionally, the phylogenetic results suggest that Liolaemus lonquimayensis is a synonym of Liolaemus elongatus.

  11. High richness of insect herbivory from the early Miocene Hindon Maar crater, Otago, New Zealand

    PubMed Central

    Lee, Daphne E.; Wappler, Torsten

    2017-01-01

    Plants and insects are key components of terrestrial ecosystems and insect herbivory is the most important type of interaction in these ecosystems. This study presents the first analysis of associations between plants and insects for the early Miocene Hindon Maar fossil lagerstätte, Otago, New Zealand. A total of 584 fossil angiosperm leaves representing 24 morphotypes were examined to determine the presence or absence of insect damage types. Of these leaves, 73% show signs of insect damage; they comprise 821 occurrences of damage from 87 damage types representing all eight functional feeding groups. In comparison to other fossil localities, the Hindon leaves display a high abundance of insect damage and a high diversity of damage types. Leaves of Nothofagus(southern beech), the dominant angiosperm in the fossil assemblage, exhibit a similar leaf damage pattern to leaves from the nearby mid to late Miocene Dunedin Volcano Group sites but display a more diverse spectrum and much higher percentage of herbivory damage than a comparable dataset of leaves from Palaeocene and Eocene sites in the Antarctic Peninsula. PMID:28224051

  12. New species of dictyostelids from Patagonia and Tierra del Fuego, Argentina.

    PubMed

    Vadell, Eduardo M; Cavender, James C; Romeralo, Maria; Edwards, Sally M; Stephenson, Steven L; Baldauf, Sandra L

    2011-01-01

    In late Jan and early Feb 2005 samples for isolation of dictyostelid cellular slime molds (dictyostelids) were collected in five different provinces and from six national parks (all located 39-55°S) in Patagonia and Tierra del Fuego, Argentina. Southern beech (Nothofagus) forests represented the primary vegetation type investigated, but some samples were obtained from Patagonian steppe, alpine meadows, Valdivian temperate rainforests and coniferous forests dominated by Araucaria, Austrocedrus and Fitzroya. Among the dictyostelids isolated from the samples we collected were seven species new to science. These species (Dictyostelium austroandinum, D. chordatum, D. fasciculoideum, D. gargantuum, D. leptosomopsis, D. valdivianum and Polysphondylium patagonicum) are described herein on the basis of both morphology and molecular (SSU rDNA) data. One of the new species, D. gargantuum, is one of the largest representatives of the group reported to date. Another unusual species, D. chordatum, produces long interwoven sorocarps that do not appear to respond to a spacing gas similar to the condition first noted in D. implicatum.

  13. Males of Hylamorpha elegans burmeister (Coleoptera: Scarabaeidae) are attracted to odors released from conspecific females.

    PubMed

    Quiroz, Andrés; Palma, Ruben; Etcheverría, Paulina; Navarro, Vicente; Rebolledo, Ramón

    2007-04-01

    The behavioral responses of Hylamorpha elegans L. (Coleoptera: Scarabaeidae, Rutelinae) to the semiochemicals released from conspecific individual adults were studied, with particular attention paid to female attraction of males. Odors released from virgin females significantly attracted male conspecifics in both the field and laboratory olfactometer and wind tunnel bioassays. However, females did not attract other females, and males attracted no one. The response of male H. elegans to (1) compounds (1,4-hydroquinone and 1,4-benzoquinone) released only by unmated females; (2) the essential oil of the secondary host (Nothofagus obliqua); and (3) the blend of 1,4-hydroquinone and 1,4-benzoquinone with N. obliqua essential oil was studied. The blend of 1,4-benzoquinone mixed with essential oil at the trial concentration was attractive with males. The same response was found with 1,4-hydroquinone alone. The essential oil did not have the expected attractant effect on conspecific males. These results suggest that, when combined with essential oil, 1,4-benzoquinone may function in the sexual behavior of males and females. These findings are discussed in terms of the ecological role of this putative sexual pheromone and its potential use in a strategy of control of this pest.

  14. Phylogeny and evolution of the Betulaceae as inferred from DNA sequences, morphology, and paleobotany.

    PubMed

    Chen, Z D; Manchester, S R; Sun, H Y

    1999-08-01

    Phylogeny of the Betulaceae is assessed on the basis of rbcL, ITS, and morphological data. Based upon 26 rbcL sequences representing most "higher" hamamelid families, the Betulaceae are monophyletic, with Casuarinaceae as its sister group, regardless of whether the outgroup is Cunoniaceae, Cercidiphyllaceae, Hamamelidaceae, or Nothofagus. Within the Betulaceae, two sister clades are evident, corresponding to the subfamilies Betuloideae and Coryloideae. However, with only 13 phylogenetically informative sites, the rbcL sequences provide limited intra-subfamilial resolution. Internal transcribed spacer (ITS) sequences provided 96 phylogenetically informative sites from 491 aligned sites resulting in a single most parsimonious tree of 374 steps (consistency index = 0.791) with two major lineages corresponding to the two traditional subfamilies: Betuloideae (Alnus, Betula) and Coryloideae (Corylus, Ostryopsis, Carpinus, Ostrya). This arrangement is mostly consistent with those from rbcL and morphology and is greatly reinforced by analyses with the three data sets combined. In the Coryloideae, the Ostryopsis-Carpinus-Ostrya clade is well supported, with Corylus as its sister group. The sister-group relationship between Ostryopsis and the Carpinus-Ostrya clade is well supported by ITS, rbcL, and morphological data. Phylogenetic relationships among the extant genera deduced by these analyses are compatible with inferences from ecological evolution and the extensive fossil record.

  15. Two new Liolaemus lizards from the Andean highlands of Southern Chile (Squamata, Iguania, Liolaemidae)

    PubMed Central

    Troncoso-Palacios, Jaime; Diaz, Hugo A.; Puas, German I.; Riveros-Riffo, Edvin; Elorza, Alvaro A.

    2016-01-01

    Abstract Liolaemus is a diverse genus of lizards, subdivided into two subgenera: Liolaemus (sensu stricto) and Eulaemus, distributed mainly in Chile and Argentina. The Liolaemus elongatus-kriegi complex is the most diverse group within Liolaemus (sensu stricto), especially the species closely related to Liolaemus elongatus, which form a clade currently comprising nine species. Several Chilean species of this group have been recently described, mainly from volcanoes and poorly explored mountains. Here molecular and morphological evidence are provided for a new species of the Liolaemus elongatus clade, which is characterized by its small size and lack of dorsal pattern, unusual features for the species of this group of lizards. Additionally, the lack of precloacal pores in males of Liolaemus (sensu stricto) is a trait found in few species, which do not constitute a monophyletic group. A second new southern Chilean species is also described, without precloacal pores and supported by molecular phylogenetics to be related to Liolaemus villaricensis. Both new species were found in the same locality, near a lake located in a pre-Andean zone with Araucaria and Nothofagus forest. The two species are dedicated to prominent Lonkos (tribal chiefs) of the Mapuche and Pehuenche people: Janequeo and Leftraru. Additionally, the phylogenetic results suggest that Liolaemus lonquimayensis is a synonym of Liolaemus elongatus. PMID:27920609

  16. From leaves to landscape: A multiscale approach to assess fire hazard in wildland-urban interface areas.

    PubMed

    Ghermandi, Luciana; Beletzky, Natacha A; de Torres Curth, Mónica I; Oddi, Facundo J

    2016-12-01

    The overlapping zone between urbanization and wildland vegetation, known as the wildland urban interface (WUI), is often at high risk of wildfire. Human activities increase the likelihood of wildfires, which can have disastrous consequences for property and land use, and can pose a serious threat to lives. Fire hazard assessments depend strongly on the spatial scale of analysis. We assessed the fire hazard in a WUI area of a Patagonian city by working at three scales: landscape, community and species. Fire is a complex phenomenon, so we used a large number of variables that correlate a priori with the fire hazard. Consequently, we analyzed environmental variables together with fuel load and leaf flammability variables and integrated all the information in a fire hazard map with four fire hazard categories. The Nothofagus dombeyi forest had the highest fire hazard while grasslands had the lowest. Our work highlights the vulnerability of the wildland-urban interface to fire in this region and our suggested methodology could be applied in other wildland-urban interface areas. Particularly in high hazard areas, our work could help in spatial delimitation policies, urban planning and development of plans for the protection of human lives and assets. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Detection of plant growth enhancing features in psychrotolerant yeasts from Patagonia (Argentina).

    PubMed

    Mestre, María Cecilia; Fontenla, Sonia; Bruzone, María Clara; Fernández, Natalia Veronica; Dames, Joanna

    2016-10-01

    This study explores the biotechnological potential for plant production of twelve psychrotolerant yeasts strains from Northwest-Patagonia. These strains were isolated from different substrates associated with Nothofagus sp. in native forests and Vaccinium sp. in a commercial plantation. Yeasts characterization was performed using in vitro assays to evaluate the production of auxin-like compounds and siderophores, ability to solubilize inorganic phosphate and to reduce common plant pathogen growth. Strain YF8.3 identified as Aureobasidium pullullans was the main producer of auxin-like and siderophores compounds. Phosphate solubilization was a characteristic observed by strains L8.12 and CRUB1775 identified as Holtermaniella takashimae and Candida maritima, respectively. Different yeast strains were able to inhibit the growth of Verticillium dahliae PPRI5569 and Pythium aphanidermatum PPRI 9009, but they all failed to inhibit the growth of Fusarium oxysporum PPRI5457. The present study, suggests that yeasts present in different environments in Northwestern-Patagonian have physiological in vitro features which may influence plant growth. These results are promising for the developing of biological products based on Patagonian yeasts for plant production in cold-temperate regions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Submillennial palynology and palaeoecology of the last glaciation at Taiquemó (˜50,000 cal yr, MIS 2 4) in southern Chile

    NASA Astrophysics Data System (ADS)

    Heusser, C. J.; Heusser, L. E.

    2006-03-01

    Stratigraphic palynology of core HE94-2B from a mire at Taiquemó (42.17°S, 73.60°W) on Isla Grande de Chiloé is one of the most closely sampled, continuous Pleistocene records in southern South America. Chronology of the 655-cm core that extends from Marine Isotope Stage (MIS) 4 through the Lateglacial is controlled by 27 finite radiocarbon dates. Sampled at 1-cm intervals, the high temporal resolution (mean ˜85 yr cm -1) captures short-term palaeoecological changes and successional restabilization of plant communities. Preponderance of Gramineae (grass) with Nothofagus dombeyi type (southern beech) characterizing Subantarctic Parkland under a cold climate in MIS 4 was followed by a conspicuously milder interval that lasted for some ten millennia in MIS 3. Of greater frequency and diversity at this time were more thermophilic taxa associated with North Patagonian Evergreen Forest ( Podocarpus, Pilgerodendron type , Pseudopanax, Myrtaceae). Subsequently with increasing cold and hyperhumidity, N. dombeyi type-Gramineae assemblages that included Subantarctic Parkland indicator taxa ( Lepidothamnus, Astelia, Gaimardia) increased stepwise in MIS 2-3. Parkland maxima in MIS 2 during the Last Glacial Maximum (LGM) date to glacial advances between ˜17,800 and 33,400 cal yr BP. On deglaciation, Lateglacial North Patagonian Evergreen Forest was subject to short-term stadial and interstadial climatic fluctuations. The high-resolution Taiquemó pollen record details and supports previous conclusions of interhemispheric synchrony of climatic and glacial events.

  19. Knowing and doing: research leading to action in the conservation of forest genetic diversity of Patagonian temperate forests.

    PubMed

    Gallo, Leonardo A; Marchelli, Paula; Chauchard, Luis; Peñalba, Marcelo Gonzalez

    2009-08-01

    Researchers dealing with conservation subjects usually do not put the results of their work into practice, even when the primary purpose of their research is the preservation of biodiversity. In the South American temperate forests we identified an area with the highest genetic diversity in Argentina of Nothofagus nervosa, one of the most relevant southern beech species. Based on the information of our scientific study and our recommendations, the authorities of Lanin National Park changed the protection status of this area to avoid logging. The new forestry management plans include consideration of "high genetic diversity" in decisions on where logging will be allowed. Results of our initial genetic study induced the analysis of biodiversity at the species and ecosystems levels, which yielded results similar to our genetic studies. A strong connection among researchers and managers from the onset of our study and the awareness of the former about the importance of the implementation of the research work were key to bridging the gap between conservation research and conservation practice.

  20. Palynological evidence for increased aridity on the central Chilean coast during the Holocene

    NASA Astrophysics Data System (ADS)

    Villagrán, Carolina; Varela, Juan

    1990-09-01

    The late Quaternary vegetation of the semiarid coast of central Chile is inferred from the palynological analysis of profiles from Quereo (31°55'S) and Quintero (32°47'S). Prior to 11,400 yr B.P., wet conditions are suggested by the abundance of pollen indicators of swamp and aquatic taxa, such as Cyperaceae and Myriophyllum, and by the presence of traces of arboreal pollen. Since ca. 10,000 yr B.P., a trend toward increasingly drier conditions is implied by the almost complete absence of arboreal and aquatic taxa, and a general decrease in the diversity of the semiarid shrubland indicators. From 3000 yr B.P. onward, the pollen records show the reappearance of swamp and aquatic taxa, presumably associated with wetter conditions, which led to recolonization by forest taxa at 1720 yr B.P. in Quintero. The drier climate detected along the semiarid coast of central Chile during most of the Holocene extended inland to the Andean foot-hills, within the present mediterranean-type climate zone of Chile, and also affected the distribution of the winter-deciduous Nothofagus forests and the northern boundary of the temperate rain forests.

  1. Relative Extents of Preformation and Neoformation in Tree Shoots: Analysis by a Deconvolution Method

    PubMed Central

    GUÉDON, YANN; PUNTIERI, J. G.; SABATIER, S.; BARTHÉLÉMY, D.

    2006-01-01

    • Background and Aims Neoformation is the process by which organs not preformed in a bud are developed on a growing shoot, generally after preformation extension. The study of neoformation in trees has been hindered due to methodological reasons. The present report is aimed at assessing the relative importance of preformation and neoformation in the development of shoots of woody species. • Methods A deconvolution method was applied to estimate the distribution of the number of neoformed organs for eight data sets corresponding to four Nothofagus species and a Juglans hybrid. • Key Results The number of preformed organs was higher and less variable than the number of neoformed organs. Neoformation contributed more than preformation to explain full-size differences between shoots developed in different positions within the architecture of each tree species. • Conclusions Differences between the distributions of the numbers of preformed and neoformed organs may be explained by alluding to the duration of differentiation and extension for each of these groups of organs. The deconvolution of distributions is a useful tool for the analysis of neoformation and shoot structure in trees. PMID:16899472

  2. Geomorphic Effect of Wood in Southern Andes Streams: Evidences From Three Mountain Basins

    NASA Astrophysics Data System (ADS)

    Andreoli, A.; Comiti, F.; Mao, L.; Lenzi, M. A.; Urciolo, A.; Iroumé, A.; Opazo, L.

    2007-05-01

    This study analyses large wood (LW) storage and the associated effects on channel morphology and flow hydraulics in three third-order mountain basins (drainage area 9-12 km2) covered in old-growth nothofagus forests, ranging from the temperate warm Chilean Andean Cordillera to the subantarctic Tierra del Fuego (Argentina). Amount, characteristics and dimensions of large wood (>10 cm large, > 1 m long) were recorded, as well as their effects on stream morphology, hydraulics and on sediment storage. Also, wood transport over a 1 year time period was assessed. Results show that major differences in LW abundance exist even between adjacent basins, due to the basins' disturbance history (fire). Massive LW volumes (i.e. > 1,000 m3ha-1) can be reached in basins disturbed by fires followed by mass movements and debris flows. However, wood mobility at bankfull conditions appears quite scarce (<4% of the logs moved), with travel distances inversely related to the piece length/channel width ratio. Potential energy dissipation due to wood dams is about a quarter of the total elevation drop in two streams, with a the gross sediment volume stored behind wood dams of around 1,000 m3km-1, which appears to be of the same order of the annual sediment yield. Finally, the presence of wood dams may increase flow resistance up to one order of magnitude.

  3. A Holocene record of climate, vegetation change and peat bog development, east Otago, South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    McGlone, Matt S.; Wilmshurst, Janet M.

    1999-05-01

    A Holocene record of pollen, macrofossils, testate amoebae and peat humification is presented from a small montane bog. Sediment accumulation began before 9000 yr BP, but peat growth not until ca. 7000 BP. From 12 000 to 7000 yr BP, a shrub-grassland dominated under a dry climate, with increasing conifer forest and tall scrub from ca. 9600 yr BP. At 7000 yr BP a dense montane-subalpine low conifer forest established under a moist, cool climatic regime. Between 7000 and 700 yr BP the bog surface was shrubby, tending to be dry but with highly variable surface wetness. The catchment was affected by major fire at least four times between 4000 and 1000 yr BP. Both fire and bog surface wetness may have been linked to ENSO-caused variations in rainfall. Cooler, cloudier winters and disturbance by fire promoted the expansion of the broadleaf tree Nothofagus menziesii between 4000 yr BP and 1300 yr BP at the expense of the previous conifer forest-scrub vegetation. Polynesian fires (ca. 700 yr BP) reduced the vegetation to tussock grassland and bracken. Deforestation did not markedly affect the hydrology of the site. European pastoralism since ad 1860 has increased run-off and rising water tables in the bog have led to a Sphagnum-dominated cover.

  4. Disturbance affects short-term facilitation, but not long-term saturation, of exotic plant invasion in New Zealand forest

    PubMed Central

    Spence, Laura A.; Ross, Joshua V.; Wiser, Susan K.; Allen, Robert B.; Coomes, David A.

    2011-01-01

    We investigate the spread of an exotic herb, Hieracium lepidulum, into a New Zealand Nothofagus forest with the aim of understanding how stand-development of tree populations, propagule pressure and invader persistence, affect invasion across the landscape and within communities. Using data repeatedly collected over 35 years, from 250 locations, we parametrize continuous-time Markov chain models and use these models to examine future projections of the invasion under a range of hypothetical scenarios. We found that the probability of invasion into a stand was relatively high following canopy disturbance and that local abundance of Hieracium was promoted by minor disturbances. However, model predictions extrapolated 45 years into the future show that neither the rate of landscape-level invasion, nor local population growth of Hieracium, was affected much by changing the frequency of canopy disturbance events. Instead, invasion levels were strongly affected by the ability of Hieracium to persist in the understorey following forest canopy closure, and by propagule supply from streams, forest edges and plants already established within the stand. Our results show that disturbance frequency has surprisingly little influence on the long-term trajectory of invasion, while invader persistence strongly determines invasion patterns. PMID:20980298

  5. Plesiosaur-bearing rocks from the Late Cretaceous Tahora Fm, Mangahouanga, New Zealand - a palaeoenvironmental study

    NASA Astrophysics Data System (ADS)

    Vajda, Vivi; Raine, J. Ian

    2010-05-01

    Mangahouanga Stream, Hawkes Bay, New Zealand is world-famous for its high southern latitude vertebrate fossils including plesiosaurs, mosasaurs and more rarely, dinosaurs. The fossils are preserved in the conglomeratic facies of the Maungataniwha Sandstone Member of the Tahora Formation. A palynological investigation of sediments from the boulders hosting vertebrate fossils reveals well-preserved palynological assemblages dominated by pollen and spores from land plants but also including marine dinoflagellate cysts in one sample. The palynofacies is strongly dominated by wood fragments including charcoal, and the sample taken from a boulder hosting plesiosaur vertebrae is entirely terrestrially derived, suggesting a fresh-water habitat for at least some of these plesiosaurs. The key-pollen taxa Nothofagidites senectus and Tricolpites lilliei, together with the dinocyst Isabelidinium pellucidum and the megaspore Grapnelispora evansii, strongly indicate an early Maastrichtian age for the host rock. The terrestrial palynoflora reflects a mixed vegetation dominated by podocarp conifers and angiosperms with a significant tree-fern subcanopy component. The presence of taxa with modern temperate distributions such as Nothofagus (southern beech), Proteaceae and Cyatheaceae (tree-ferns), indicates a mild-temperate climate and lack of severe winter freezing during the latest Cretaceous, providing an ecosystem which most probably made it possible for polar dinosaurs to overwinter. The paper is dedicated to Mrs Joan Wiffen who with her great persistence, enthusiasm and courage put Mangahouanga on the world map, becoming a role model for many young scientists.

  6. Solid-state spectroscopic analysis of lignins from several Austral hardwoods.

    PubMed

    Martínez, A T; Almendros, G; González-Vila, F J; Fründ, R

    1999-10-01

    In order to gain information about lignin molecular characteristics with a direct bearing on the remarkable susceptibility of some Austral hardwoods to biological delignification, milled-wood lignins were isolated and analyzed by spectroscopic techniques in the solid state. Cross polarization and magic-angle spinning 13C nuclear magnetic resonance (13C CPMAS NMR) and Fourier-transform infrared (FTIR) spectra of the lignin preparations were obtained. The most diagnostic peaks were assigned and quantified as percentages of the total spectral area, and the differences observed discussed in terms of lignin composition. The spectral patterns obtained revealed that the woods from Gevuina avellana, Eucryphia cordifolia and Nothofagus dombeyii have lignin with high syringyl/guaiacyl ratio, as evidenced by relative areas of 13C NMR signals at 153 and 148 ppm, and FTIR bands at 1,335 and 1,275 cm-1. The presence of syringyl-rich lignins, characterized by lower redox potential and condensation degree than guaiacyl-rich lignins, could be a structural factor contributing to the ease of extensive delignification of these woods by white-rot fungi.

  7. Differential snow accumulation and melt at southern hemisphere deciduous forested sites

    NASA Astrophysics Data System (ADS)

    McPhee, James; Huerta, Marlene; Molotch, Noah

    2016-04-01

    Little is known about the differential snow dynamics resulting from forest cover in southern hemisphere alpine regions. Tree species variability and differences in local climate preclude extrapolation of northern hemisphere results and introduce uncertainty on the future impacts of climate change on snow-cover duration, maximum accumulation and melt rates. This research presents preliminary results from field observations obtained at an experimental watershed in the Nevados de Chillan region, in south-central Chile. The relatively low elevation of the Andes Cordillera and higher latitude of the site allows the existence of mixed Nothofagus forests, sometimes combined with bamboo-type undergrowth. Rain-on-snow events can be observed during winter and in the early stages of the austral spring. We installed four instrument clusters at the Valle Hermoso experimental catchments, where snow depth, air temperature and relative humidity were measured both under canopy and in forest clearings. The clusters where positioned in order to cover a range of elevations and sun exposure. Preliminary results from two winter seasons suggest that forest cover can impact accumulation rates as much as elevation does, and that melt rates are fairly sensitive to forest cover even in low LAI conditions.

  8. Aggregate structure and stability linked to carbon dynamics in a south Chilean Andisol

    NASA Astrophysics Data System (ADS)

    Huygens, D.; Boeckx, P.; van Cleemput, O.; Godoy, R.; Oyarzún, C.

    2005-02-01

    The extreme vulnerability of soil organic carbon to climate and land use change emphasizes the need for further research in different terrestrial ecosystems. We have studied the aggregate stability and carbon dynamics in a chronosequence of three different land uses in a south Chilean Andisols: a second growth Nothofagus obliqua forest (SGFOR), a grassland (GRASS) and a Pinus radiata plantation (PINUS). The aim of this study was to investigate the role of Al as soil organic matter stabilizing agent in this Andisol. In a case study, we linked differences in carbon dynamics between the three land use treatments to physical protection and recalcitrance of the soil organic matter (SOM). In this study, C aggregate stability and dynamics were studied using size and density fractionation experiments of the SOM, δ13C and total carbon analysis of the different SOM fractions, and mineralization measurements. The results showed that electrostatic attractions between and among Al-oxides and clay minerals are mainly responsible for the stabilization of soil aggregates and the physical protection of the enclosed soil organic carbon. Whole soil C mineralization rate constants were highest for SGFOR and PINUS, followed by GRASS. In contrast, incubation experiments of isolated macro organic matter fractions showed that the recalcitrance of the SOM decreased in another order: PINUS > SGFOR > GRASS. We concluded that physical protection of soil aggregates was the main process determining whole soil C mineralization. Land use changes affected soil organic carbon dynamics in this south Chilean Andisol by altering soil pH and consequently available Al.

  9. Population genetic structure of a colonising, triploid weed, Hieracium lepidulum.

    PubMed

    Chapman, H; Robson, B; Pearson, M L

    2004-03-01

    Understanding the breeding system and population genetic structure of invasive weed species is important for biocontrol, and contributes to our understanding of the evolutionary processes associated with invasions. Hieracium lepidulum is an invasive weed in New Zealand, colonising a diverse range of habitats including native Nothofagus forest, pine plantations, scrubland and tussock grassland. It is competing with native subalpine and alpine grassland and herbfield vegetation. H. lepidulum is a triploid, diplosporous apomict, so theoretically all seed is clonal, and there is limited potential for the creation of variation through recombination. We used intersimple sequence repeats (ISSRs) to determine the population genetic structure of New Zealand populations of H. lepidulum. ISSR analysis of five populations from two regions in the South Island demonstrated high intrapopulation genotypic diversity, and high interpopulation genetic structuring; PhiST = 0.54 over all five populations. No private alleles were found in any of the five populations, and allelic differentiation was correlated to geographic distance. Cladistic compatibility analysis indicated that both recombination and mutation were important in the creation of genotypic diversity. Our data will contribute to any biocontrol program developed for H. lepidulum. It will also be a baseline data set for future comparisons of genetic structure during the course of H. lepidulum invasions.

  10. Net primary production of forests: a constant fraction of gross primary production?

    PubMed

    Waring, R. H.; Landsberg, J. J.; Williams, M.

    1998-02-01

    Considerable progress has been made in our ability to model and measure annual gross primary production (GPP) by terrestrial vegetation. But challenges remain in estimating maintenance respiration (R(m)) and net primary production (NPP). To search for possible common relationships, we assembled annual carbon budgets from six evergreen and one deciduous forest in Oregon, USA, three pine plantations in New South Wales, Australia, a deciduous forest in Massachusetts, USA, and a Nothofagus forest on the South Island of New Zealand. At all 12 sites, a standard procedure was followed to estimate annual NPP of foliage, branches, stems, and roots, the carbon expended in synthesis of these organs (R(g)), their R(m), and that of previously produced foliage and sapwood in boles, branches, and large roots. In the survey, total NPP ranged from 120 to 1660 g C m(-2) year(-1), whereas the calculated fraction allocated to roots varied from 0.22 to 0.63. Comparative analysis indicated that the total NPP/GPP ratio was conservative (0.47 +/- 0.04 SD). This finding supports the possibility of greatly simplifying forest growth models. The constancy of the NPP/GPP ratio also provides an incentive to renew efforts to understand the environmental factors affecting partitioning of NPP above and belowground.

  11. Paleoenvironmental and paleoclimatic investigations on Isla de los Estados, Argentina

    NASA Astrophysics Data System (ADS)

    Björck, S.; Fernandez, M.; Hjort, C.; Ljung, K.; Martinez, O.; Möller, P.; Ponce, F.; Rabassa, J.; Roig, F.; Unkel, I.; Wohlfarth, B.

    2007-05-01

    The expedition in November-December 2005 to Isla de los Estados (Staten Island) off the southeastern tip of South America was a cooperative venture between Lund University (LU) and Stockholm University (SU) in Sweden and the CADIC-CONICET Institute in Ushuaia, Argentina. The aim of the expedition was threefold: (1) to extend the Swedish paleoclimatic "ATLANTIS"-project (Greenland, Iceland, Faroe Islands, Azores, Grenada, Tristan da Cunha; PI S Björck) to the southern part of the South American continent, (2) to connect earlier glacial and climate history reconstructions from the Antarctic Peninsula to equivalents north of the Drake Passage in southernmost South America, and (3) to complement paleo-information available from the Tierra del Fuego mainland with information from Isla de los Estados. Focus was on two areas in the northern and north-western part of the island, Bahía Colnett and Bahia Crossley. Detailed geomorphologic and stratigraphic mapping of glacial deposits were combined with sampling sediments for OSL dating. To reconstruct the paleoclimatic development of Isla de los Estados since the last ice retreat, four main peat bog/lake sites were cored and sampled. In addition, living trees of Nothofagus and old logs preserved in the peat were sampled for dendrochronological and dendroclimatological studies. Preliminary results show that the deglaciation of the study area occurred before 16500 cal yr BP. Detailed multi- proxy analyses of the four sequences are under way and first results will be presented.

  12. Palo Podrido: Model for Extensive Delignification of Wood by Ganoderma applanatum

    PubMed Central

    Dill, Ingrid; Kraepelin, Gunda

    1986-01-01

    Chemical and micromorphological analysis revealed that South Chilean “palo podrido” results from a white-rot fungus that causes highly selective and extensive delignification. Palo podrido samples from 10 different hardwood trunks (Eucryphia cordifolia, Drimys winteri, and Nothofagus dombeyi) decayed by Ganoderma applanatum were analyzed. Of 14 samples, 11 had extremely low Klason lignin values, ranging from 6.1 to 0.4% (dry weight). The most remarkable and unusual feature was that delignification and defibration were not restricted to small pockets but extended throughout large areas in the interior of trunks subjected to undisturbed rotting over long periods of time. Comparative analysis of water content, swelling capacity, and lignin content led to the conclusion that besides lignin degradation, suppression of the cellulolytic activity of the rotting organisms plays a decisive role. Among various nutrients added to a palo podrido sample (3% residual Klason lignin), the nitrogen source was the only one leading to almost complete cellulose degradation. We suggest that the extremely low nitrogen content (0.037 to 0.073% [dry weight]) of the investigated wood species was the primary cause for the extensive delignification as well as the concomitant suppression of cellulose breakdown. The low temperatures, high humidity, and microaerobic conditions maintained within the decaying trunks are discussed as additional ecological factors favoring delignification in South Chilean rain forests. Images PMID:16347235

  13. Saccharomyces eubayanus and Saccharomyces uvarum associated with the fermentation of Araucaria araucana seeds in Patagonia.

    PubMed

    Rodríguez, M Eugenia; Pérez-Través, Laura; Sangorrín, Marcela P; Barrio, Eladio; Lopes, Christian A

    2014-09-01

    Mudai is a traditional fermented beverage, made from the seeds of the Araucaria araucana tree by Mapuche communities. The main goal of the present study was to identify and characterize the yeast microbiota responsible of Mudai fermentation as well as from A. araucana seeds and bark from different locations in Northern Patagonia. Only Hanseniaspora uvarum and a commercial bakery strain of Saccharomyces cerevisiae were isolated from Mudai and all Saccharomyces isolates recovered from A. araucana seed and bark samples belonged to the cryotolerant species Saccharomyces eubayanus and Saccharomyces uvarum. These two species were already reported in Nothofagus trees from Patagonia; however, this is the first time that they were isolated from A. araucana, which extends their ecological distribution. The presence of these species in A. araucana seeds and bark samples, led us to postulate a potential role for them as the original yeasts responsible for the elaboration of Mudai before the introduction of commercial S. cerevisiae cultures. The molecular and genetic characterization of the S. uvarum and S. eubayanus isolates and their comparison with European S. uvarum strains and S. eubayanus hybrids (S. bayanus and S. pastorianus), allowed their ecology and evolution us to be examined.

  14. Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast.

    PubMed

    Libkind, Diego; Hittinger, Chris Todd; Valério, Elisabete; Gonçalves, Carla; Dover, Jim; Johnston, Mark; Gonçalves, Paula; Sampaio, José Paulo

    2011-08-30

    Domestication of plants and animals promoted humanity's transition from nomadic to sedentary lifestyles, demographic expansion, and the emergence of civilizations. In contrast to the well-documented successes of crop and livestock breeding, processes of microbe domestication remain obscure, despite the importance of microbes to the production of food, beverages, and biofuels. Lager-beer, first brewed in the 15th century, employs an allotetraploid hybrid yeast, Saccharomyces pastorianus (syn. Saccharomyces carlsbergensis), a domesticated species created by the fusion of a Saccharomyces cerevisiae ale-yeast with an unknown cryotolerant Saccharomyces species. We report the isolation of that species and designate it Saccharomyces eubayanus sp. nov. because of its resemblance to Saccharomyces bayanus (a complex hybrid of S. eubayanus, Saccharomyces uvarum, and S. cerevisiae found only in the brewing environment). Individuals from populations of S. eubayanus and its sister species, S. uvarum, exist in apparent sympatry in Nothofagus (Southern beech) forests in Patagonia, but are isolated genetically through intrinsic postzygotic barriers, and ecologically through host-preference. The draft genome sequence of S. eubayanus is 99.5% identical to the non-S. cerevisiae portion of the S. pastorianus genome sequence and suggests specific changes in sugar and sulfite metabolism that were crucial for domestication in the lager-brewing environment. This study shows that combining microbial ecology with comparative genomics facilitates the discovery and preservation of wild genetic stocks of domesticated microbes to trace their history, identify genetic changes, and suggest paths to further industrial improvement.

  15. Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast

    PubMed Central

    Libkind, Diego; Hittinger, Chris Todd; Valério, Elisabete; Gonçalves, Carla; Dover, Jim; Johnston, Mark; Gonçalves, Paula; Sampaio, José Paulo

    2011-01-01

    Domestication of plants and animals promoted humanity's transition from nomadic to sedentary lifestyles, demographic expansion, and the emergence of civilizations. In contrast to the well-documented successes of crop and livestock breeding, processes of microbe domestication remain obscure, despite the importance of microbes to the production of food, beverages, and biofuels. Lager-beer, first brewed in the 15th century, employs an allotetraploid hybrid yeast, Saccharomyces pastorianus (syn. Saccharomyces carlsbergensis), a domesticated species created by the fusion of a Saccharomyces cerevisiae ale-yeast with an unknown cryotolerant Saccharomyces species. We report the isolation of that species and designate it Saccharomyces eubayanus sp. nov. because of its resemblance to Saccharomyces bayanus (a complex hybrid of S. eubayanus, Saccharomyces uvarum, and S. cerevisiae found only in the brewing environment). Individuals from populations of S. eubayanus and its sister species, S. uvarum, exist in apparent sympatry in Nothofagus (Southern beech) forests in Patagonia, but are isolated genetically through intrinsic postzygotic barriers, and ecologically through host-preference. The draft genome sequence of S. eubayanus is 99.5% identical to the non-S. cerevisiae portion of the S. pastorianus genome sequence and suggests specific changes in sugar and sulfite metabolism that were crucial for domestication in the lager-brewing environment. This study shows that combining microbial ecology with comparative genomics facilitates the discovery and preservation of wild genetic stocks of domesticated microbes to trace their history, identify genetic changes, and suggest paths to further industrial improvement. PMID:21873232

  16. Baseline element composition of foliose and fruticose lichens along the steep climatic gradient of SW Patagonia (Aisén Region, Chile).

    PubMed

    Monaci, Fabrizio; Fantozzi, Federica; Figueroa, Ricardo; Parra, Oscar; Bargagli, Roberto

    2012-09-01

    Samples of foliose (Nephroma antarcticum) and fruticose (Usnea sp.) lichens were collected across a steep climatic and vegetation gradient in a remote, almost pristine region of SW Chilean Patagonia. Concentrations of major and trace elements in lichens from the rainforest were among the lowest ever reported worldwide for foliose and fruticose lichens and can be considered background levels for the region. The two lichen growth forms showed different elemental compositions mainly due to the greater capacity of foliose thalli to intercept elements from windborne and canopy-leached particles. The patterns of spatial variation in the chemical composition of lichens were effectively explained by statistical methods and reflected the different availability of wet and dry deposition along the steep climatic gradient. Baseline values established for N. antarcticum samples growing in temperate Nothofagus forests were therefore distinct from those of samples growing in more open, drier habitats. The fruticose Usnea sp. showed a higher affinity for atmophile Hg, low concentrations of lithophilic elements, and the same baseline composition whether from temperate forests or from dry, barren environments. The provided background and baseline values against which variations can be measured will be useful in the early detection of local or regional climatic and environmental change, especially in view of the planned construction of hydropower dams under the recently approved HidroAysén Project.

  17. Palynological analysis of camelid coprolites: seasonality in the use of the site Cerro Casa de Piedra 7 (Santa Cruz, Argentina)

    NASA Astrophysics Data System (ADS)

    Velázquez, Nadia Jimena; Burry, Lidia Susana; Fugassa, Martín Horacio; Civalero, María Teresa; Aschero, Carlos Alberto

    2014-01-01

    Palynological, palaeoparasitological and paleobotanical studies of coprolites found in archaeological sites from Perito Moreno National Park (47°57‧S72°05‧W) yielded information on diet, palaeoenvironment and health. These studies allowed adding evidence to the reconstruction of life history of the hunter-gatherers that inhabited Patagonia during the Holocene. We examined the season of the year when camelid Lama guanicoe coprolites (5400 ± 64 yr 14C BP to 9640 ± 190 yr 14C BP) were deposited at Cerro Casa de Piedra 7 (site CCP7). The study used palynological evidence and comparison with pollen spectra of modern feces collected during summer, fall, winter and spring of 2010. The dominant types were: pollen of Nothofagus, Empetrum rubrum, Asteraceae subfam. Asteroideae, Nassauvia, Caryophyllaceae and Poaceae; fern spores; remains of Eimeria macusaniensis; and plant remains of Poaceae, Festuca pallescens, Stipa speciosa, Armeria maritima, Gaultheria mucronata and E. rubrum. Pollen spectra of modern and fossil feces were used for multivariate analysis. Coprolites associated to fall and winter modern feces. These results and those obtained from pollen concentration values and the presence of pollen types indicators of seasonality, allowed the determination of summer, fall and winter coprolites. However, caution must be taken with the seasonality results of coprolites dated earlier than 9000 years BP since the environmental conditions differed from now. The site was probably a camelid shelter during the unfavorable seasons.

  18. [Maternal factors associated with low birth weight].

    PubMed

    Heredia-Olivera, Karen; Munares-García, Oscar

    2016-01-01

    Introducción: En el Perú, el bajo peso al nacimiento es un indicador de riesgo de problemas perinatales y de la infancia, el objetivo del estudio fue determinar los factores maternos asociados al bajo peso al nacimiento. Métodos: Estudio de casos y controles, en 123 recién nacidos de bajo peso (casos) y 123 recién nacidos de peso normal (controles) pareados por fecha de nacimiento y distrito. Se indagaron factores maternos asociados al bajo peso al nacimiento y se comparó entre casos y controles. Se aplicó Chi cuadrada, Odds ratio (OR) con sus intervalos de confianza al 95% (IC 95%), regresión logística binaria y curva ROC. Resultados: Se encontraron asociaciones para antecedentes maternos de bajo peso (OR: 41.1; IC 95%: 5.5-306.7); prematuridad (OR: 12.0; IC 95%: 1.5-94.3), antecedente de eclampsia (OR: 5.8; IC 95%: 1.9-17.4), 1 a 3 controles prenatales (OR: 5.7; IC 95%: 2.6-12.3), gestación múltiple (OR: 4.7; IC 95%: 1.3-17.0) y consumo de tabaco (OR: 3.8; IC 95%: 1.5-9.8), el no ser adolescente (OR: 0.3; IC 95%: 0.1-0.6), y no tener un intervalo intergenésico corto (OR: 0.2; IC 95%: 0.1-0.7). El análisis multivariado nos indicó que el tener entre 1 a 3 controles prenatales, gestación múltiple, ser adolescente y un intervalo intergenésico corto se asocian al bajo peso al nacimiento, el modelo propuesto explicó el 18.6% del evento, el área bajo la curva fue 72.9% considerando que predice adecuadamente (p ˂ 0.001). Conclusiones: Existen factores de riesgo materno asociados al bajo peso al nacimiento en gestantes de zona urbana de la costa como el tener de 1 a 3 controles prenatales, gestación múltiple, ser adolescente y tener un periodo entre embarazos menor a dos años.

  19. Spawning aggregations of three protogynous groupers in the southern Gulf of Mexico.

    PubMed

    Tuz-Sulub, A; Brulé, T

    2015-01-01

    Spawning aggregations of red hind Epinephelus guttatus, tiger grouper Mycteroperca tigris and yellowfin grouper Mycteroperca venenosa were identified at two coral-reef systems: Arrecife Alacranes (emergent bank reef) and Bajos del Norte (submerged bank reef) on the continental shelf of the Yucatan Peninsula (Campeche Bank), Mexico. At both reefs, E. guttatus forms large spawning aggregations between February and March. At Bajos del Norte, M. tigris reproduces in a small, low-density aggregation in May, while M. venenosa aggregates at high densities for spawning between March and May. Multi-species use of an aggregation site by E. guttatus and M. venenosa was observed at Bajos del Norte. The identified spawning aggregations are apparently stable in location over time, and all three species were commonly observed to spawn within 1 week following the full moon. Development and survival of the larvae spawned in these aggregations are probably aided by a seasonal (spring-summer) upwelling in the north-east Campeche Bank. A permanent area closure at Bajos del Norte, currently outside any specific fisheries management area or regulations, would provide protection needed for the spawning aggregations of these three species. © 2014 The Fisheries Society of the British Isles.

  20. Misión de operaciones en ambientes extremos

    NASA Image and Video Library

    ¿En qué lugar del planeta se puede entrenar un astronauta en un entorno similar al espacio? ¿Qué les parece bajo el agua? NEEMO es un proyecto que envía a grupos de astronautas, ingenieros, médicos...

  1. Desechos y reciclaje

    EPA Pesticide Factsheets

    Aprenda acerca de los residuos generados por los hogares y las industrias, incluyendo desechos sólidos y peligrosos y su eliminación adecuada. EPA es responsable de regular estos residuos bajo la Ley de Conservación y Recuperación de Recursos ( RCRA ).

  2. Development of Mitochondrial Loop-Mediated Isothermal Amplification for Detection of the Small Liver Fluke Opisthorchis viverrini (Opisthorchiidae; Trematoda; Platyhelminthes)

    PubMed Central

    Nguyen, Nga Thi Bich; Truong, Nam Hai; De, Nguyen Van

    2012-01-01

    Mitochondrial DNA sequences offer major advantages over the more usual nuclear targets for loop-mediated isothermal amplification approaches (mito-LAMP) because multiple copies occur in every cell. Four LAMP primers [F3, FIP(F1c+F2), BIP(B1c+B2), and B3] were designed based on the mitochondrial nad1 sequence of Opisthorchis viverrini and used for a highly specific assay (mito-OvLAMP) to distinguish DNA of O. viverrini from that of another opisthorchiid (Clonorchis sinensis) and other trematodes (Haplorchis pumilio, Haplorchis taichui, Fasciola hepatica, and Fasciola gigantica). Conventional PCR was applied using F3/B3 primer pairs to verify the specificity of the primers for O. viverrini DNA templates. All LAMP-positive samples could be detected with the naked eye in sunlight, by gel electrophoresis (stained with ethidium bromide), and by addition of SYBR green I to the product in sunlight or under UV light. Only DNA from O. viverrini yielded amplification products by LAMP (and by PCR verification), and the LAMP limit of detection was as little as 100 fg (10−4 ng DNA), indicating that this assay is 10 to 100 times more sensitive than PCR. Field testing was done using representative egg and metacercarial samples collected from localities where the fluke is endemic. With the advantages of simplicity, rapidity, sensitivity, and cost effectiveness, mito-OvLAMP is a good tool for molecular detection and epidemiology studies in regions or countries where O. viverrini is endemic, which can lead to more effective control of opisthorchiasis and trematodiasis. PMID:22322346

  3. Development of mitochondrial loop-mediated isothermal amplification for detection of the small liver fluke Opisthorchis viverrini (Opisthorchiidae; Trematoda; Platyhelminthes).

    PubMed

    Le, Thanh Hoa; Nguyen, Nga Thi Bich; Truong, Nam Hai; De, Nguyen Van

    2012-04-01

    Mitochondrial DNA sequences offer major advantages over the more usual nuclear targets for loop-mediated isothermal amplification approaches (mito-LAMP) because multiple copies occur in every cell. Four LAMP primers [F3, FIP(F1c+F2), BIP(B1c+B2), and B3] were designed based on the mitochondrial nad1 sequence of Opisthorchis viverrini and used for a highly specific assay (mito-OvLAMP) to distinguish DNA of O. viverrini from that of another opisthorchiid (Clonorchis sinensis) and other trematodes (Haplorchis pumilio, Haplorchis taichui, Fasciola hepatica, and Fasciola gigantica). Conventional PCR was applied using F3/B3 primer pairs to verify the specificity of the primers for O. viverrini DNA templates. All LAMP-positive samples could be detected with the naked eye in sunlight, by gel electrophoresis (stained with ethidium bromide), and by addition of SYBR green I to the product in sunlight or under UV light. Only DNA from O. viverrini yielded amplification products by LAMP (and by PCR verification), and the LAMP limit of detection was as little as 100 fg (10(-4) ng DNA), indicating that this assay is 10 to 100 times more sensitive than PCR. Field testing was done using representative egg and metacercarial samples collected from localities where the fluke is endemic. With the advantages of simplicity, rapidity, sensitivity, and cost effectiveness, mito-OvLAMP is a good tool for molecular detection and epidemiology studies in regions or countries where O. viverrini is endemic, which can lead to more effective control of opisthorchiasis and trematodiasis.

  4. Monitoring of RNA Dynamics in Living Cells Using PUM-HD and Fluorescent Protein Reconstitution Technique.

    PubMed

    Yoshimura, H; Ozawa, T

    2016-01-01

    Fluorescence live-cell RNA imaging to monitor the intracellular localization and dynamics of the target RNA is a challenging subject. One of the difficulties to achieve this is to establish a precise method to enable a fluorescent labeling to the target RNA in living cells. Technologies to reduce the background fluorescence and to detect the RNA with high sensitivity are also necessary to visualize and analyze the intracellular localization and dynamic of the target RNA precisely. Especially in monitoring single-molecule motion, a special setup of a microscope system is required. Such technical problems make the live-cell RNA imaging to be a difficult subject. We recently developed a methodology to label and to visualize a target RNA in living cells with low background fluorescence by using a probe that is based on an RNA-binding protein domain PUM-HD (pumilio homology domain) and a fluorescent protein reconstitution method. A noteworthy property of PUM-HD to apply RNA probes is that this protein domain can be modified to recognize a particular 8-base RNA sequence by inducing tailor-made designed mutagenesis. The fluorescent protein reconstitution method allows us to detect the target RNA with high signal-to-noise ratio. Using the probe based on PUM-HD, a fluorescent protein reconstitution method, and a homebuilt fluorescent microscope system, we succeeded in single-molecule observation of a target RNA in living cells. In this chapter, the techniques to establish the probe and to observe the motion of single-molecule RNA are described. © 2016 Elsevier Inc. All rights reserved.

  5. Minor Histocompatibility Antigens Are Expressed in Syncytiotrophoblast and Trophoblast Debris

    PubMed Central

    Holland, Olivia J.; Linscheid, Caitlin; Hodes, Herbert C.; Nauser, Traci L.; Gilliam, Melissa; Stone, Peter; Chamley, Larry W.; Petroff, Margaret G.

    2012-01-01

    The fetal semi-allograft can induce expansion and tolerance of antigen-specific maternal T and B cells through paternally inherited major histocompatibility complex and minor histocompatibility antigens (mHAgs). The effects of these antigens have important consequences on the maternal immune system both during and long after pregnancy. Herein, we investigate the possibility that the placental syncytiotrophoblast and deported trophoblastic debris serve as sources of fetal mHAgs. We mapped the expression of four mHAgs (human mHAg 1, pumilio domain-containing protein KIAA0020, B-cell lymphoma 2–related protein A1, and ribosomal protein S4, Y linked) in the placenta. Each of these proteins was expressed in several placental cell types, including the syncytiotrophoblast. These antigens and two additional Y chromosome–encoded antigens [DEAD box polypeptide 3, Y linked (DDX3Y), and lysine demethylase5D] were also identified by RT-PCR in the placenta, purified trophoblast cells, and cord blood cells. Finally, we used a proteomic approach to investigate the presence of mHAgs in the syncytiotrophoblast and trophoblast debris shed from first-trimester placenta. By this method, four antigens (DDX3Y; ribosomal protein S4, Y linked; solute carrier 1A5; and signal sequence receptor 1) were found in the syncytiotrophoblast, and one antigen (DDX3Y) was found in shed trophoblast debris. The finding of mHAgs in the placenta and in trophoblast debris provides the first direct evidence that fetal antigens are present in debris shed from the human placenta. The data, thus, suggest a mechanism by which the maternal immune system is exposed to fetal alloantigens, possibly explaining the relationship between parity and graft-versus-host disease. PMID:22079431

  6. Coordinate post-transcriptional repression of Dpp-dependent transcription factors attenuates signal range during development.

    PubMed

    Newton, Fay G; Harris, Robin E; Sutcliffe, Catherine; Ashe, Hilary L

    2015-10-01

    Precise control of the range of signalling molecule action is crucial for correct cell fate patterning during development. For example, Drosophila ovarian germline stem cells (GSCs) are maintained by exquisitely short-range BMP signalling from the niche. In the absence of BMP signalling, one GSC daughter differentiates into a cystoblast (CB) and this fate is stabilised by Brain tumour (Brat) and Pumilio (Pum)-mediated post-transcriptional repression of mRNAs, including that encoding the Dpp transducer, Mad. However, the identity of other repressed mRNAs and the mechanism of post-transcriptional repression are currently unknown. Here, we identify the Medea and schnurri mRNAs, which encode transcriptional regulators required for activation and/or repression of Dpp target genes, as additional Pum-Brat targets, suggesting that tripartite repression of the transducers is deployed to desensitise the CB to Dpp. In addition, we show that repression by Pum-Brat requires recruitment of the CCR4 and Pop2 deadenylases, with knockdown of deadenylases in vivo giving rise to ectopic GSCs. Consistent with this, Pum-Brat repression leads to poly(A) tail shortening and mRNA degradation in tissue culture cells, and we detect a reduced number of Mad and shn transcripts in the CB relative to the GSC based on single molecule mRNA quantitation. Finally, we show generality of the mechanism by demonstrating that Brat also attenuates pMad and Dpp signalling range in the early embryo. Together our data serve as a platform for understanding how post-transcriptional repression restricts interpretation of BMPs and other cell signals in order to allow robust cell fate patterning during development.

  7. Ultraviolet radiation influences perch selection by a neotropical poison-dart frog.

    PubMed

    Kats, Lee B; Bucciarelli, Gary M; Schlais, David E; Blaustein, Andrew R; Han, Barbara A

    2012-01-01

    Ambient ultraviolet-B radiation can harm amphibian eggs, larvae and adults. However, some amphibians avoid UV-B radiation when given the opportunity. The strawberry poison dart frog, Oophaga pumilio, is diurnal and males vocalize throughout the day in light gaps under forest canopies that expose them to solar radiation. Previous studies have demonstrated that males calling from high perches are more successful at mating than those at lower perches. We investigated whether frogs at higher perches receive more ultraviolet-B than those calling from lower perches. We also investigated whether frogs on perches receiving relatively low ultraviolet-B levels maintained their positions for longer compared to individuals calling from perches receiving higher levels of ultraviolet-B. Finally, since it has been hypothesized that some animals utilize levels of UV-A as a visual cue to avoid UV-B damage, we artificially elevated ultraviolet-A levels to examine whether males exposed to artificially elevated ultraviolet-A abandoned their perches sooner compared to males exposed to visible light. We found that frogs called from perches receiving low ultraviolet-B regardless of perch height, and that frogs maintain their positions longer on perches receiving low ultraviolet-B compared to perches receiving even slightly higher ultraviolet-B levels. Exposing the frogs to artificially elevated levels of ultraviolet-A radiation caused males to move off of their perches faster than when they were exposed to a control light source. These experiments suggest that ultraviolet radiation plays an important role in frog behavior related to perch selection, even in rainforests where much of the solar radiation is shielded by the forest canopy.

  8. Both thyroid hormone levels and resting metabolic rate decrease in African striped mice when food availability decreases.

    PubMed

    Rimbach, Rebecca; Pillay, Neville; Schradin, Carsten

    2017-03-01

    In response to variation in food availability and ambient temperature (Ta), many animals show seasonal adaptations in their physiology. Laboratory studies showed that thyroid hormones are involved in the regulation of metabolism, and their regulatory function is especially important when the energy balance of an individual is compromised. However, little is known about the relationship between thyroid hormones and metabolism in free-living animals and animals inhabiting seasonal environments. Here, we studied seasonal changes in triiodothyronine (T3) levels, resting metabolic rate (RMR) and two physiological markers of energy balance (blood glucose and ketone bodies) in 61 free-living African striped mice (Rhabdomys pumilio) that live in an semi-arid environment with food shortage during the dry season. We predicted a positive relationship between T3 levels and RMR. Further, we predicted higher T3 levels, blood glucose levels and RMR, but lower ketone body concentrations, during the moist season when food availability is high compared with summer when food availability is low. RMR and T3 levels were negatively related in the moist season but not in the dry season. Both RMR and T3 levels were higher in the moist than in the dry season, and T3 levels increased with increasing food availability. In the dry season, blood glucose levels were lower but ketone body concentrations were higher, indicating a change in substrate use. Seasonal adjustments in RMR and T3 levels permit a reduction of energy expenditure when food is scarce, and reflect an adaptive response to reduced food availability in the dry season. © 2017. Published by The Company of Biologists Ltd.

  9. The essential functions of KREPB4 are developmentally distinct and required for endonuclease association with editosomes.

    PubMed

    McDermott, Suzanne M; Stuart, Kenneth

    2017-08-11

    Uridine insertion and deletion RNA editing generates functional mitochondrial mRNAs in Trypanosoma brucei, and several transcripts are differentially edited in bloodstream (BF) and procyclic form (PF) cells correlating with changes in mitochondrial function. Editing is catalyzed by three ∼20S editosomes that have a common set of 12 proteins, but are typified by mutually exclusive RNase III KREN1, N2, and N3 endonucleases with distinct cleavage specificities. KREPB4 is a common editosome protein that has a degenerate RNase III domain lacking conserved catalytic residues, in addition to zinc-finger and Pumilio/fem-3 mRNA binding factor (PUF) motifs. Here we show that KREPB4 is essential for BF and PF growth, in vivo RNA editing, and editosome integrity, but that loss of KREPB4 has differential effects on editosome component and complexes between BF and PF cells. We used targeted mutagenesis to investigate the functions of the conserved PUF and RNase III domains in both life-cycle stages and show that the PUF motif is not essential for function in BF or PF. In contrast, specific mutations in the RNase III domain severely inhibit BF and PF growth and editing, and disrupt ~20S editosomes, while others indicate that the RNase III domain is noncatalytic. We further show that KREPB4, specifically the noncatalytic RNase III domain, is required for the association of KREN1, N2, and N3 with PF editosomes. These results, combined with previous studies, support a model in which KREPB4 acts as a pseudoenzyme to form the noncatalytic half of an RNase III heterodimer with the editing endonucleases. Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  10. Evidence for Novel Hepaciviruses in Rodents

    PubMed Central

    Drexler, Jan Felix; Corman, Victor Max; Müller, Marcel Alexander; Lukashev, Alexander N.; Gmyl, Anatoly; Coutard, Bruno; Adam, Alexander; Ritz, Daniel; Leijten, Lonneke M.; van Riel, Debby; Kallies, Rene; Klose, Stefan M.; Gloza-Rausch, Florian; Binger, Tabea; Annan, Augustina; Adu-Sarkodie, Yaw; Oppong, Samuel; Bourgarel, Mathieu; Rupp, Daniel; Hoffmann, Bernd; Schlegel, Mathias; Kümmerer, Beate M.; Krüger, Detlev H.; Schmidt-Chanasit, Jonas; Setién, Alvaro Aguilar; Cottontail, Veronika M.; Hemachudha, Thiravat; Wacharapluesadee, Supaporn; Osterrieder, Klaus; Bartenschlager, Ralf; Matthee, Sonja; Beer, Martin; Kuiken, Thijs; Reusken, Chantal; Leroy, Eric M.; Ulrich, Rainer G.; Drosten, Christian

    2013-01-01

    Hepatitis C virus (HCV) is among the most relevant causes of liver cirrhosis and hepatocellular carcinoma. Research is complicated by a lack of accessible small animal models. The systematic investigation of viruses of small mammals could guide efforts to establish such models, while providing insight into viral evolutionary biology. We have assembled the so-far largest collection of small-mammal samples from around the world, qualified to be screened for bloodborne viruses, including sera and organs from 4,770 rodents (41 species); and sera from 2,939 bats (51 species). Three highly divergent rodent hepacivirus clades were detected in 27 (1.8%) of 1,465 European bank voles (Myodes glareolus) and 10 (1.9%) of 518 South African four-striped mice (Rhabdomys pumilio). Bats showed anti-HCV immunoblot reactivities but no virus detection, although the genetic relatedness suggested by the serologic results should have enabled RNA detection using the broadly reactive PCR assays developed for this study. 210 horses and 858 cats and dogs were tested, yielding further horse-associated hepaciviruses but none in dogs or cats. The rodent viruses were equidistant to HCV, exceeding by far the diversity of HCV and the canine/equine hepaciviruses taken together. Five full genomes were sequenced, representing all viral lineages. Salient genome features and distance criteria supported classification of all viruses as hepaciviruses. Quantitative RT-PCR, RNA in-situ hybridisation, and histopathology suggested hepatic tropism with liver inflammation resembling hepatitis C. Recombinant serology for two distinct hepacivirus lineages in 97 bank voles identified seroprevalence rates of 8.3 and 12.4%, respectively. Antibodies in bank vole sera neither cross-reacted with HCV, nor the heterologous bank vole hepacivirus. Co-occurrence of RNA and antibodies was found in 3 of 57 PCR-positive bank vole sera (5.3%). Our data enable new hypotheses regarding HCV evolution and encourage efforts to

  11. Inferring Predator Behavior from Attack Rates on Prey-Replicas That Differ in Conspicuousness

    PubMed Central

    2012-01-01

    Behavioral ecologists and evolutionary biologists have long studied how predators respond to prey items novel in color and pattern. Because a predatory response is influenced by both the predator’s ability to detect the prey and a post-detection behavioral response, variation among prey types in conspicuousness may confound inference about post-prey-detection predator behavior. That is, a relatively high attack rate on a given prey type may result primarily from enhanced conspicuousness and not predators’ direct preference for that prey. Few studies, however, account for such variation in conspicuousness. In a field experiment, we measured predation rates on clay replicas of two aposematic forms of the poison dart frog Dendrobates pumilio, one novel and one familiar, and two cryptic controls. To ask whether predators prefer or avoid a novel aposematic prey form independently of conspicuousness differences among replicas, we first modeled the visual system of a typical avian predator. Then, we used this model to estimate replica contrast against a leaf litter background to test whether variation in contrast alone could explain variation in predator attack rate. We found that absolute predation rates did not differ among color forms. Predation rates relative to conspicuousness did, however, deviate significantly from expectation, suggesting that predators do make post-detection decisions to avoid or attack a given prey type. The direction of this deviation from expectation, though, depended on assumptions we made about how avian predators discriminate objects from the visual background. Our results show that it is important to account for prey conspicuousness when investigating predator behavior and also that existing models of predator visual systems need to be refined. PMID:23119039

  12. Validation of endogenous control reference genes for normalizing gene expression studies in endometrial carcinoma.

    PubMed

    Ayakannu, Thangesweran; Taylor, Anthony H; Willets, Jonathon M; Brown, Laurence; Lambert, David G; McDonald, John; Davies, Quentin; Moss, Esther L; Konje, Justin C

    2015-09-01

    Real-time quantitative RT-PCR (qRT-PCR) is a powerful technique used for the relative quantification of target genes, using reference (housekeeping) genes for normalization to ensure the generation of accurate and robust data. A systematic examination of the suitability of endogenous reference genes for gene expression studies in endometrial cancer tissues is absent. The aims of this study were therefore to identify and evaluate from the thirty-two possible reference genes from a TaqMan(®) array panel their suitability as an internal control gene. The mathematical software packages geNorm qBasePLUS identified Pumilio homolog 1 (Drosophila) (PUM1), ubiquitin C (UBC), phosphoglycerate kinase (PGK1), mitochondrial ribosomal protein L19 (MRPL19) and peptidylpropyl isomerase A (cyclophilin A) (PPIA) as the best reference gene combination, whilst NormFinder identified MRPL19 as the best single reference gene, with importin 8 (IPO8) and PPIA being the best combination of two reference genes. BestKeeper ranked MRPL19 as the most stably expressed gene. In addition, the study was validated by examining the relative expression of a test gene, which encodes the cannabinoid receptor 1 (CB1). A significant difference in CB1 mRNA expression between malignant and normal endometrium using MRPL19, PPIA, and IP08 in combination was observed. The use of MRPL19, IPO8 and PPIA was identified as the best reference gene combination for the normalization of gene expression levels in endometrial carcinoma. This study demonstrates that the arbitrary selection of endogenous control reference genes for normalization in qRT-PCR studies of endometrial carcinoma, without validation, risks the production of inaccurate data and should therefore be discouraged.

  13. Adaptation for rodent pollination in Leucospermum arenarium (Proteaceae) despite rapid pollen loss during grooming

    PubMed Central

    Johnson, Christopher Michael; Pauw, Anton

    2014-01-01

    Background and Aims Plants are adapted for rodent pollination in diverse and intricate ways. This study explores an extraordinary example of these adaptations in the pincushion Leucospermum arenarium (Proteaceae) from South Africa. Methods Live trapping and differential exclusion experiments were used to test the role of rodents versus birds and insects as pollinators. To explore the adaptive significance of geoflory, inflorescences were raised above ground level and seed production was compared. Captive rodents and flowers with artificial stigmas were used to test the effect of grooming on the rate of pollen loss. Microscopy, nectar composition analysis and manipulative experiments were used to investigate the bizarre nectar production and transport system. Key Results Differential exclusion of rodents, birds and insects demonstrated the importance of rodents in promoting seed production. Live trapping revealed that hairy-footed gerbils, Gerbillurus paeba, and striped field mice, Rhabdomys pumilio, both carried L. arenarium pollen on their forehead and rostrum, but much larger quantities ended up in faeces as a result of grooming. Terrarium experiments showed that grooming exponentially diminished the pollen loads that they carried. The nectar of L. arenarium was found to be unusually viscous and to be presented in a novel location on the petal tips, where rodents could access it without destroying the flowers. Nectar was produced inside the perianth, but was translocated to the petal tips via capillary ducts. In common with many other rodent-pollinated plants, the flowers are presented at ground level, but when raised to higher positions seed production was not reduced, indicating that selection through female function does not drive the evolution of geoflory. Conclusions Despite the apparent cost of pollen lost to grooming, L. arenarium has evolved remarkable adaptations for rodent pollination and provides the first case of this pollination system in the genus

  14. Regulation of membrane excitability: a convergence on voltage-gated sodium conductance.

    PubMed

    Lin, Wei-Hsiang; Baines, Richard A

    2015-02-01

    The voltage-gated sodium channel (Nav) plays a key role in regulation of neuronal excitability. Aberrant regulation of Nav expression and/or function can result in an imbalance in neuronal activity which can progress to epilepsy. Regulation of Nav activity is achieved by coordination of a multitude of mechanisms including RNA alternative splicing and translational repression. Understanding of these regulatory mechanisms is complicated by extensive genetic redundancy: the mammalian genome encodes ten Navs. By contrast, the genome of the fruitfly, Drosophila melanogaster, contains just one Nav homologue, encoded by paralytic (DmNa v ). Analysis of splicing in DmNa v shows variants exhibit distinct gating properties including varying magnitudes of persistent sodium current (INaP). Splicing by Pasilla, an identified RNA splicing factor, alters INaP magnitude as part of an activity-dependent mechanism. Enhanced INaP promotes membrane hyperexcitability that is associated with seizure-like behaviour in Drosophila. Nova-2, a mammalian Pasilla homologue, has also been linked to splicing of Navs and, moreover, mouse gene knockouts display seizure-like behaviour.Expression level of Navs is also regulated through a mechanism of translational repression in both flies and mammals. The translational repressor Pumilio (Pum) can bind to Na v transcripts and repress the normal process of translation, thus regulating sodium current (INa) density in neurons. Pum2-deficient mice exhibit spontaneous EEG abnormalities. Taken together, aberrant regulation of Nav function and/or expression is often epileptogenic. As such, a better understanding of regulation of membrane excitability through RNA alternative splicing and translational repression of Navs should provide new leads to treat epilepsy.

  15. Ultraviolet Radiation Influences Perch Selection by a Neotropical Poison-Dart Frog

    PubMed Central

    Kats, Lee B.; Bucciarelli, Gary M.; Schlais, David E.; Blaustein, Andrew R.; Han, Barbara A.

    2012-01-01

    Ambient ultraviolet-B radiation can harm amphibian eggs, larvae and adults. However, some amphibians avoid UV-B radiation when given the opportunity. The strawberry poison dart frog, Oophaga pumilio, is diurnal and males vocalize throughout the day in light gaps under forest canopies that expose them to solar radiation. Previous studies have demonstrated that males calling from high perches are more successful at mating than those at lower perches. We investigated whether frogs at higher perches receive more ultraviolet-B than those calling from lower perches. We also investigated whether frogs on perches receiving relatively low ultraviolet-B levels maintained their positions for longer compared to individuals calling from perches receiving higher levels of ultraviolet-B. Finally, since it has been hypothesized that some animals utilize levels of UV-A as a visual cue to avoid UV-B damage, we artificially elevated ultraviolet-A levels to examine whether males exposed to artificially elevated ultraviolet-A abandoned their perches sooner compared to males exposed to visible light. We found that frogs called from perches receiving low ultraviolet-B regardless of perch height, and that frogs maintain their positions longer on perches receiving low ultraviolet-B compared to perches receiving even slightly higher ultraviolet-B levels. Exposing the frogs to artificially elevated levels of ultraviolet-A radiation caused males to move off of their perches faster than when they were exposed to a control light source. These experiments suggest that ultraviolet radiation plays an important role in frog behavior related to perch selection, even in rainforests where much of the solar radiation is shielded by the forest canopy. PMID:23251505

  16. Current status of food-borne parasitic zoonoses in Laos.

    PubMed

    Giboda, M; Ditrich, O; Scholz, T; Viengsay, T; Bouaphanh, S

    1991-12-01

    Stool samples from a total of 1,008 persons were examined for intestinal parasites during a comprehensive study on the epidemiology of small fluke infections in Laos. The prevalence of small fluke eggs in the stool was seen to peak at age 20 years, particularly in men from villages (90.4%). Three quarters of infections belong to the category of light infections and only 0.6% to the category of very heavy according to eggs per gram of feces (EPG). The highest EPG was in the 11-15 year age group. In addition, the following parasites were diagnosed: Sarcocystis hominis (prevalence more than 10% in the group over 20 years of age), Taenia sp. (12.4% for the village people over 20 years), Fasciolopsts buski (3.8% for the same group). The habit of Laos people to eat raw fish, beef and pork flesh, is reflected in significant epidemiological consequences. Cercariae of Opisthorchis viverrini occurred in 0.5% of Bithynia siamensis goniomphalus examined, Haplorchis sp. cercariae were found in 0.9% of Tarebia granifera snails. Metacercariae of O. viverrini were found in flesh of 7 species of cyprinid fish. Haplorchis taichui in 4 species of these fish, and H. pumilio of two cyprinid species. Hampala macrolepidota harbored larvae of all above mentioned species. Stellantchasmus falcatus was recovered in fins of belonid fish Xenentodon cancila. Adults of O. viverrini were found in 36% of domestic and stray cats, Heterophyid flukes were found in 24% cats. The most frequent species were H. taichui and H. yokogawai. Eight Laotian students were treated in Czechoslovakia with praziquantel to determine fluke infection. Three were infected only by O. viverrini, four only by H. taichui and one by both O. viverrini and H. taichui. These results demonstrate the problem of correct differential diagnosis of food-borne small fluke infections and the need to assess the clinical course and public health aspects of infections.

  17. Conserved Regulation of MAP Kinase Expression by PUF RNA-Binding Proteins

    PubMed Central

    Lee, Myon-Hee; Hook, Brad; Pan, Guangjin; Kershner, Aaron M; Merritt, Christopher; Seydoux, Geraldine; Thomson, James A; Wickens, Marvin; Kimble, Judith

    2007-01-01

    Mitogen-activated protein kinase (MAPK) and PUF (for Pumilio and FBF [fem-3 binding factor]) RNA-binding proteins control many cellular processes critical for animal development and tissue homeostasis. In the present work, we report that PUF proteins act directly on MAPK/ERK-encoding mRNAs to downregulate their expression in both the Caenorhabditis elegans germline and human embryonic stem cells. In C. elegans, FBF/PUF binds regulatory elements in the mpk-1 3′ untranslated region (3′ UTR) and coprecipitates with mpk-1 mRNA; moreover, mpk-1 expression increases dramatically in FBF mutants. In human embryonic stem cells, PUM2/PUF binds 3′UTR elements in both Erk2 and p38α mRNAs, and PUM2 represses reporter constructs carrying either Erk2 or p38α 3′ UTRs. Therefore, the PUF control of MAPK expression is conserved. Its biological function was explored in nematodes, where FBF promotes the self-renewal of germline stem cells, and MPK-1 promotes oocyte maturation and germ cell apoptosis. We found that FBF acts redundantly with LIP-1, the C. elegans homolog of MAPK phosphatase (MKP), to restrict MAPK activity and prevent apoptosis. In mammals, activated MAPK can promote apoptosis of cancer cells and restrict stem cell self-renewal, and MKP is upregulated in cancer cells. We propose that the dual negative regulation of MAPK by both PUF repression and MKP inhibition may be a conserved mechanism that influences both stem cell maintenance and tumor progression. PMID:18166083

  18. Phenotypic screen for RNAi effects in the codling moth Cydia pomonella.

    PubMed

    Wang, Jinda; Gu, Liuqi; Ireland, Stephen; Garczynski, Stephen F; Knipple, Douglas C

    2015-11-10

    RNAi-based technologies have the potential to augment, or replace existing pest management strategies. However, some insect taxa are less susceptible to the induction of the post-transcriptional gene silencing effect than others, such as the Lepidoptera. Here we describe experiments to investigate the induction of RNAi in the codling moth, Cydia pomonella, a major lepidopteran pest of apple, pear, and walnut. Prior to a knockdown screen, fluorescently labeled small interfering RNA (siRNA) and double-stranded RNA (dsRNA) derived from green fluorescent protein (GFP) coding sequence were delivered to the surface of artificial diet to which neonate larvae were introduced and subsequently examined for the distribution of fluorescence in their tissues. Fluorescence was highly concentrated in the midgut but its presence in other tissues was equivocal. Next, dsRNAs were made for C. pomonella genes orthologous to those that have well defined deleterious phenotypes in Drosophila melanogaster. A screen was conducted using dsRNAs encoding cullin-1 (Cpcul1), maleless (Cpmle), musashi (Cpmsi), a homeobox gene (CpHbx), and pumilio (Cppum). The dsRNAs designed from these target genes were administered to neonate larvae by delivery to the surface of the growth medium. None of the dsRNA treatments affected larval viability, however Cpcul1-dsRNA had a significant effect on larval growth, with the average length of larvae about 3mm, compared to about 4mm in the control groups. Measurement of Cpcul1 transcript levels by quantitative real-time PCR (qRT-PCR) revealed a dose-dependent RNAi effect in response to increasing amount of Cpcul1-dsRNA. Despite their reduced size, Cpcul1-dsRNA-treated larvae molted normally and matured to adulthood in a manner similar to controls. In an additional experiment, Cpcul1-siRNA was found to induce similar stunting effect as that induced by Cpcul1-dsRNA.

  19. Alternative reproductive tactics in female striped mice: heavier females are more likely to breed solitarily than communally.

    PubMed

    Hill, Davina L; Pillay, Neville; Schradin, Carsten

    2015-11-01

    Alternative reproductive tactics (ARTs) are discrete reproductive phenotypes governed by decision rules called strategies. ARTs are fixed for life in species with alternative strategies, while tactic expression is plastic in species with a single strategy. ARTs have been investigated in males of many species, but few studies have tested whether the same theoretical framework applies in females. Female striped mice (Rhabdomys pumilio) employ three ARTs: communal breeders give birth in a nest shared with female kin and a breeding male and show allo-parental care; returners give birth away from the shared nest and later return to it; and solitary breeders give birth away from the shared nest and do not return to the group. Here, studying free-living female striped mice over six breeding seasons, we tested whether ARTs arise from alternative strategies or a single strategy. We also asked to what extent stochastic extrinsic factors explain whether individuals become solitary rather than group living. Females switched tactics, consistent with a single strategy, so we tested whether this represented a mixed or conditional single strategy. Only the latter predicts differences between ARTs in traits indicating competitive ability, such as body mass or age, before individuals adopt a tactic. We weighed females at conception when they were still group living to eliminate potential confounding effects of gestation and subsequent social tactic (solitary versus group living) on body mass. Females that went on to use a solitary ART were heavier than those that became communal breeders and returners, in support of a conditional strategy. Solitary breeders also arose through extrinsic factors (mortality of all adult female group members). They weighed less than females that became solitary while relatives were alive, but did not differ in body mass from communal breeders and returners. We conclude that ART theory applies to both sexes, with female striped mice following a

  20. Inferring predator behavior from attack rates on prey-replicas that differ in conspicuousness.

    PubMed

    Stuart, Yoel E; Dappen, Nathan; Losin, Neil

    2012-01-01

    Behavioral ecologists and evolutionary biologists have long studied how predators respond to prey items novel in color and pattern. Because a predatory response is influenced by both the predator's ability to detect the prey and a post-detection behavioral response, variation among prey types in conspicuousness may confound inference about post-prey-detection predator behavior. That is, a relatively high attack rate on a given prey type may result primarily from enhanced conspicuousness and not predators' direct preference for that prey. Few studies, however, account for such variation in conspicuousness. In a field experiment, we measured predation rates on clay replicas of two aposematic forms of the poison dart frog Dendrobates pumilio, one novel and one familiar, and two cryptic controls. To ask whether predators prefer or avoid a novel aposematic prey form independently of conspicuousness differences among replicas, we first modeled the visual system of a typical avian predator. Then, we used this model to estimate replica contrast against a leaf litter background to test whether variation in contrast alone could explain variation in predator attack rate. We found that absolute predation rates did not differ among color forms. Predation rates relative to conspicuousness did, however, deviate significantly from expectation, suggesting that predators do make post-detection decisions to avoid or attack a given prey type. The direction of this deviation from expectation, though, depended on assumptions we made about how avian predators discriminate objects from the visual background. Our results show that it is important to account for prey conspicuousness when investigating predator behavior and also that existing models of predator visual systems need to be refined.

  1. Transcriptome profiles of Penaeus (Marsupenaeus) japonicus animal and vegetal half-embryos: identification of sex determination, germ line, mesoderm, and other developmental genes.

    PubMed

    Sellars, Melony J; Trewin, Carolyn; McWilliam, Sean M; Glaves, R S E; Hertzler, Philip L

    2015-06-01

    There is virtually no knowledge of the molecular events controlling early embryogenesis in Penaeid shrimp. A combination of controlled spawning environment, shrimp embryo micro-dissection techniques, and next-generation sequencing was used to produce transcriptome EST datasets of Penaeus japonicus animal and vegetal half-embryos. Embryos were collected immediately after spawning, and then blastomeres were separated at the two-cell stage and allowed to develop to late gastrulation, then pooled for RNA isolation and cDNA synthesis. Ion Torrent sequencing of cDNA from approximately 500 pooled animal and vegetal half-embryos from multiple spawnings resulted in 560,516 and 493,703 reads, respectively. Reads from each library were assembled and Gene Ontogeny analysis produced 3479 annotated animal contigs and 4173 annotated vegetal contigs, with 159/139 hits for developmental processes in the animal/vegetal contigs, respectively. Contigs were subject to BLAST for selected developmental toolbox genes. Some of the genes found included the sex determination genes sex-lethal and transformer; the germ line genes argonaute 1, boule, germ cell-less, gustavus, maelstrom, mex-3, par-1, pumilio, SmB, staufen, and tudor; the mesoderm genes brachyury, mef2, snail, and twist; the axis determination/segmentation genes β-catenin, deformed, distal-less, engrailed, giant, hairy, hunchback, kruppel, orthodenticle, patched, tailless, and wingless/wnt-8c; and a number of cell-cycle regulators. Animal and vegetal contigs were computationally subtracted from each other to produce sets unique to either half-embryo library. Genes expressed only in the animal half included bmp1, kruppel, maelstrom, and orthodenticle. Genes expressed only in the vegetal half included boule, brachyury, deformed, dorsal, engrailed, hunchback, spalt, twist, and wingless/wnt-8c.

  2. Farm-Level Risk Factors for Fish-Borne Zoonotic Trematode Infection in Integrated Small-Scale Fish Farms in Northern Vietnam

    PubMed Central

    Phan, Van Thi; Ersbøll, Annette Kjær; Nguyen, Khue Viet; Madsen, Henry; Dalsgaard, Anders

    2010-01-01

    Background Northern Vietnam is an endemic region for fish-borne zoonotic trematodes (FZT), including liver and intestinal flukes. Humans acquire the FZT infection by eating raw or inadequately cooked fish. The production of FZT-free fish in aquaculture is a key component in establishing a sustainable program to prevent and control the FZT transmission to humans. Interventions in aquaculture should be based on knowledge of the main risk factors associated with FZT transmission. Methodology/Principal Findings A longitudinal study was carried out from June 2006 to May 2007 in Nam Dinh province, Red River Delta to investigate the development and risk factors of FZT infections in freshwater cultured fish. A total of 3820 fish were sampled six times at two-month intervals from 96 fish farms. Logistic analysis with repeated measurements was used to evaluate potential risk factors based on information collected through questionnaire interviews with 61 fish farm owners. The results showed that the FZT infections significantly increased from first sampling in June to July 2006 (65%) to sixth sampling in April to May, 2007 (76%). The liver fluke, Clonorchis sinensis and different zoonotic intestinal flukes including Haplochis pumilio, H. taichui, H. yokogawai, Centrocestus formosanus and Procerovum varium were found in sampled fish. Duration of fish cultured (sampling times), mebendazole drug self-medication of household members, presence of snails in the pond, and feeding fish with green vegetation collected outside fish farms all had a significant effect on the development of FZT prevalence in the fish. Conclusions/Significance The FZT prevalence in fish increased by 11 percentage points during a one-year culture period and the risk factors for the development of infection were identified. Results also highlight that the young fish are already highly infected when stocked into the grow-out systems. This knowledge should be incorporated into control programs of FZT

  3. Adaptation for rodent pollination in Leucospermum arenarium (Proteaceae) despite rapid pollen loss during grooming.

    PubMed

    Johnson, Christopher Michael; Pauw, Anton

    2014-05-01

    Plants are adapted for rodent pollination in diverse and intricate ways. This study explores an extraordinary example of these adaptations in the pincushion Leucospermum arenarium (Proteaceae) from South Africa. Live trapping and differential exclusion experiments were used to test the role of rodents versus birds and insects as pollinators. To explore the adaptive significance of geoflory, inflorescences were raised above ground level and seed production was compared. Captive rodents and flowers with artificial stigmas were used to test the effect of grooming on the rate of pollen loss. Microscopy, nectar composition analysis and manipulative experiments were used to investigate the bizarre nectar production and transport system. Differential exclusion of rodents, birds and insects demonstrated the importance of rodents in promoting seed production. Live trapping revealed that hairy-footed gerbils, Gerbillurus paeba, and striped field mice, Rhabdomys pumilio, both carried L. arenarium pollen on their forehead and rostrum, but much larger quantities ended up in faeces as a result of grooming. Terrarium experiments showed that grooming exponentially diminished the pollen loads that they carried. The nectar of L. arenarium was found to be unusually viscous and to be presented in a novel location on the petal tips, where rodents could access it without destroying the flowers. Nectar was produced inside the perianth, but was translocated to the petal tips via capillary ducts. In common with many other rodent-pollinated plants, the flowers are presented at ground level, but when raised to higher positions seed production was not reduced, indicating that selection through female function does not drive the evolution of geoflory. Despite the apparent cost of pollen lost to grooming, L. arenarium has evolved remarkable adaptations for rodent pollination and provides the first case of this pollination system in the genus.

  4. The PUF binding landscape in metazoan germ cells

    PubMed Central

    Prasad, Aman; Porter, Douglas F.; Kroll-Conner, Peggy L.; Mohanty, Ipsita; Ryan, Anne R.; Crittenden, Sarah L.; Wickens, Marvin; Kimble, Judith

    2016-01-01

    PUF (Pumilio/FBF) proteins are RNA-binding proteins and conserved stem cell regulators. The Caenorhabditis elegans PUF proteins FBF-1 and FBF-2 (collectively FBF) regulate mRNAs in germ cells. Without FBF, adult germlines lose all stem cells. A major gap in our understanding of PUF proteins, including FBF, is a global view of their binding sites in their native context (i.e., their “binding landscape”). To understand the interactions underlying FBF function, we used iCLIP (individual-nucleotide resolution UV crosslinking and immunoprecipitation) to determine binding landscapes of C. elegans FBF-1 and FBF-2 in the germline tissue of intact animals. Multiple iCLIP peak-calling methods were compared to maximize identification of both established FBF binding sites and positive control target mRNAs in our iCLIP data. We discovered that FBF-1 and FBF-2 bind to RNAs through canonical as well as alternate motifs. We also analyzed crosslinking-induced mutations to map binding sites precisely and to identify key nucleotides that may be critical for FBF–RNA interactions. FBF-1 and FBF-2 can bind sites in the 5′UTR, coding region, or 3′UTR, but have a strong bias for the 3′ end of transcripts. FBF-1 and FBF-2 have strongly overlapping target profiles, including mRNAs and noncoding RNAs. From a statistically robust list of 1404 common FBF targets, 847 were previously unknown, 154 were related to cell cycle regulation, three were lincRNAs, and 335 were shared with the human PUF protein PUM2. PMID:27165521

  5. The Smaug RNA-Binding Protein Is Essential for microRNA Synthesis During the Drosophila Maternal-to-Zygotic Transition

    PubMed Central

    Luo, Hua; Li, Xiao; Claycomb, Julie M.; Lipshitz, Howard D.

    2016-01-01

    Metazoan embryos undergo a maternal-to-zygotic transition (MZT) during which maternal gene products are eliminated and the zygotic genome becomes transcriptionally active. During this process, RNA-binding proteins (RBPs) and the microRNA-induced silencing complex (miRISC) target maternal mRNAs for degradation. In Drosophila, the Smaug (SMG), Brain tumor (BRAT), and Pumilio (PUM) RBPs bind to and direct the degradation of largely distinct subsets of maternal mRNAs. SMG has also been shown to be required for zygotic synthesis of mRNAs and several members of the miR-309 family of microRNAs (miRNAs) during the MZT. Here, we have carried out global analysis of small RNAs both in wild-type and in smg mutants. Our results show that 85% of all miRNA species encoded by the genome are present during the MZT. Whereas loss of SMG has no detectable effect on Piwi-interacting RNAs (piRNAs) or small interfering RNAs (siRNAs), zygotic production of more than 70 species of miRNAs fails or is delayed in smg mutants. SMG is also required for the synthesis and stability of a key miRISC component, Argonaute 1 (AGO1), but plays no role in accumulation of the Argonaute family proteins associated with piRNAs or siRNAs. In smg mutants, maternal mRNAs that are predicted targets of the SMG-dependent zygotic miRNAs fail to be cleared. BRAT and PUM share target mRNAs with these miRNAs but not with SMG itself. We hypothesize that SMG controls the MZT, not only through direct targeting of a subset of maternal mRNAs for degradation but, indirectly, through production and function of miRNAs and miRISC, which act together with BRAT and/or PUM to control clearance of a distinct subset of maternal mRNAs. PMID:27591754

  6. Potential role of Nanos3 in maintaining the undifferentiated spermatogonia population.

    PubMed

    Lolicato, Francesca; Marino, Rita; Paronetto, Maria Paola; Pellegrini, Manuela; Dolci, Susanna; Geremia, Raffaele; Grimaldi, Paola

    2008-01-15

    Nanos gene encodes for zinc-finger protein with putative RNA-binding activity which shows an evolutionary conserved function in germ cell development. In the mouse, three Nanos homologs have been identified: Nanos1, Nanos2 and Nanos3. The Nanos3 ortholog is expressed in both male and female gonads of early embryo and, after birth, it is found only in the testis. Nanos3 targeted disruption results in the complete loss of germ cells in both sexes; however the role of Nanos3 in the testis during the postnatal period has not been explored yet. In this study, we show that, in prepuberal testis, Nanos3 is expressed in undifferentiated spermatogonia and that its up-regulation causes accumulation of cells in the G1 phase, indicating that this protein is able to delay the cell cycle progression of spermatogonial cells. This is in line with the observation that the cell cycle length of the undifferentiated germ cells is longer than in differentiating spermatogonia. We also demonstrate a conserved mechanism of action of Nanos3, involving the interaction with the murine RNA-binding protein Pumilio2 and consisting of a potential translational repressor activity. According to the possible role of Nanos3 in inhibiting spermatogonia cell differentiation, we show that treatment with the differentiating factor all-trans retinoic acid induces a dramatic down-regulation of its expression. These results allow to conclude that, in the prepuberal testis, Nanos3 is important to maintain undifferentiated spermatogonia via the regulation of their cell cycle.

  7. Testing evolutionary hypotheses for phenotypic divergence using landscape genetics.

    PubMed

    Funk, W Chris; Murphy, Melanie A

    2010-02-01

    Understanding the evolutionary causes of phenotypic variation among populations has long been a central theme in evolutionary biology. Several factors can influence phenotypic divergence, including geographic isolation, genetic drift, divergent natural or sexual selection, and phenotypic plasticity. But the relative importance of these factors in generating phenotypic divergence in nature is still a tantalizing and unresolved problem in evolutionary biology. The origin and maintenance of phenotypic divergence is also at the root of many ongoing debates in evolutionary biology, such as the extent to which gene flow constrains adaptive divergence (Garant et al. 2007) and the relative importance of genetic drift, natural selection, and sexual selection in initiating reproductive isolation and speciation (Coyne & Orr 2004). In this issue, Wang & Summers (2010) test the causes of one of the most fantastic examples of phenotypic divergence in nature: colour pattern divergence among populations of the strawberry poison frog (Dendrobates pumilio) in Panama and Costa Rica (Fig. 1). This study provides a beautiful example of the use of the emerging field of landscape genetics to differentiate among hypotheses for phenotypic divergence. Using landscape genetic analyses, Wang & Summers were able to reject the hypotheses that colour pattern divergence is due to isolation-by-distance (IBD) or landscape resistance. Instead, the hypothesis left standing is that colour divergence is due to divergent selection, in turn driving reproductive isolation among populations with different colour morphs. More generally, this study provides a wonderful example of how the emerging field of landscape genetics, which has primarily been applied to questions in conservation and ecology, now plays an essential role in evolutionary research.

  8. Foraging in space and time structure an African small mammal community.

    PubMed

    Abu Baker, Mohammad A; Brown, Joel S

    2014-06-01

    We used live-trapping and foraging to test for the effect of habitat selection and diet on structuring a community of six small mammals and one bird within the Soutpansberg, South Africa. We established grids that straddled adjacent habitats: woodland, rocky hillside, and grassland. Trapping and foraging were used to estimate abundance, habitat use, and species-specific foraging costs. The species with the highest abundance and foraging activity in a habitat, activity time, or food was considered the most efficient and presumed to have a competitive advantage. All species exhibited distinct patterns of spatial and temporal habitat preference which provided the main mechanism of coexistence, followed by diet selection. The study species were organized into three assemblages (α diversity): grassland, Rhabdomys pumilio, Dendromus melanotis, and Mus minutoides.; woodland, Aethomys ineptus and Micaelamys namaquensis; and rock-dwelling, M. namaquensis and Elephantulus myurus. Francolinus natalensis foraged in open rocky areas and under wooded islands within the grassland. Species organization across the habitats suggested that feeding opportunities are available within all habitats; however, distinct habitat preferences resulted from differing foraging aptitudes and efficiencies of the competing species. At Lajuma, species distribution and coexistence are promoted through distinct habitat preferences that were shaped by competition and species-specific foraging costs. The combination of trapping and foraging provided a mechanistic approach that integrates behavior into community ecology by 'asking' the animal to reveal its perspective of the environment. Using spatial and temporal foraging decisions-as behavioral indicators-enables us to guide our understanding for across-taxa species coexistence.

  9. Antarctic Miocene Climate

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A. R.

    2013-12-01

    Fossils from Antarctic Miocene terrestrial deposits, coupled with stratigraphic, geochemical and paleontological data from marine boreholes, provide new insights into the climatic history of the continent. During the Miocene, ice caps coalesced to form ice sheets and vegetated surfaces gave way to barren expanses. The cryospheric changes especially have global climatic implications. The fossil data consists of diatoms, pollen and spores, and macroscopic remains of plants, ostracods, insects, molluscs and a fish. Plant fossils include wood and leaves of Nothofagus (southern beech), seeds of several vascular plants, including Ranunculus (buttercup), Hippuris (mare's-tail) and Myriophyllum (watermilfoil), megaspores of Isoetes (quillwort), and moss species. The insect chitin consists of larval head capsules of Chironomidae (midges) and exoskeletal parts of Coleoptera (beetles). The molluscs include freshwater gastropods and bivalves. The majority of these taxa are likely descendants of taxa that had survived on the continent from the Paleogene or earlier. Even though early Miocene glaciations may have been large, the climate was never cold enough to cause the extinction of the biota, which probably survived in coastal refugia. Early Miocene (c. 20 Ma) macrofossils from the McMurdo Dry Valleys (77°S) support palynological interpretations from the Cape Roberts and ANDRILL marine records that the upland vegetation was a shrub tundra. Mean summer temperature (MST) in the uplands was c. 6°C and possibly higher at the coast. The climate was wet, supporting mires and lakes. By the mid-Miocene, even though the climate continued to be wet. MST was c. 4°C which was too cold to support Nothofagus and most vascular plant species. Stratigraphic evidence indicates that the time between the Early and Mid-Miocene was a time of repeated ice advances and retreats of small glaciers originating from ice caps. At c. 14 Ma there appears to have been a modal shift in climate to

  10. Can ectomycorrhizal symbiosis and belowground plant traits be used as ecological tools to mitigate erosion on degraded slopes in the ultramafic soils of New Caledonia?

    NASA Astrophysics Data System (ADS)

    Demenois, Julien; Carriconde, Fabian; Rey, Freddy; Stokes, Alexia

    2015-04-01

    forest with dominance of Arillastrum gummiferum, dense humid forest with dominance of Nothofagus aequilateralis, and finally mixed dense humid forest. These types of vegetation are widely represented on ultramafic soils of New Caledonia and are likely to correspond to different successional phases. At the scale of species, dominant species in the above-mentioned types of vegetation are considered for herbaceous, shrubs and trees strata. Root traits of Costularia nervosa, Tristaniopsis glauca, Nothofagus aequilateralis and Arillastrum gummiferum are then characterized in situ. These species are of particular interest for post-mining ecological restoration in New Caledonia as they are light-tolerant, endemic, associated with ECM (except for Costularia nervosa) and of particular interest or already used by mining operators for post-mining ecological restoration. For both scales (community and species), soil characteristics will be collected. Very fine and fine roots, mean root diameter, root diameter diversity, root mass density, root length density, and specific root length will be considered. Degree of ectomycorrhization and fungal biomass through qPCR will be determined. Soil aggregate stability will be measured according to the standardized method NF X 31-515. Besides, greenhouse trials with Costularia nervosa, Tristaniopsis glauca and Arillastrum gummiferum are carried out to assess the influence of plant root traits, fungal inoculation and soil aggregate stability. Controlled plant inoculations are performed using available pure fungal strains isolated from New Caledonian ultramafic soils. Plants have been bred on sterilized soil samples from the field sites. Through this study, we target to identify associations between ECM fungi and plant species that could mitigate the erodibility of degraded ultramafic soils and then water erosion. A better knowledge of interactions between soil aggregate stability, ECM fungi and plant root traits is then expected to answer the

  11. Late Holocene Lacustrine Records of Climate and Vegetation Change From Southernmost South America

    NASA Astrophysics Data System (ADS)

    Moy, C. M.; Dunbar, R. B.; Francois, J.; Moreno, P. I.; Villa Martínez, R.

    2006-12-01

    The westerly wind field is one of the most prominent atmospheric circulation features in the Southern Hemisphere and has a major impact on the climate of southern South America as well as Southern Ocean hydrography. Southernmost South America is well-located to investigate past changes in the westerly winds because regional precipitation variability is controlled by the location and intensity of the wind field and it is the only landmass to extend within the core of the westerlies. Here we present late Holocene lacustrine records of climate change related to the westerlies from southern Patagonia, Chile. We focus on Lago Guanaco, a small hydrologically closed-basin lake in Southern Patagonia, and use stable isotope and pollen data from this site and three additional lakes in order to reconstruct changes in moisture balance related to the westerlies. Lago Guanaco (51°S, 72°W) is located close to the Nothofagus forest-Patagonian Steppe transition in the eastern region of Parque Nacional Torres del Paine. The location and composition of this important biological discontinuity is highly sensitive to the W-E precipitation gradient throughout Patagonia. The 4.75 m sediment core we obtained from the center of the lake has high concentrations of organic mater in addition to ostracodes and bivalves, which are relatively rare in Chilean Patagonia. Eleven AMS radiocarbon dates on organic and carbonate fractions indicate that the record spans the last ~14,400 cal yr BP and modern dates from core tops suggest little influence by old carbon sources. Changes in moisture balance and forest density/proximity are reflected in downcore variations in δ18Obivalve and δ18Oostracode, the Nothofagus/Poaceae paleovegetation index, and the C/N ratio of bulk decalcified organic matter. Combined, these variables document changes in the isotopic composition of the lake water, which largely reflect the isotopic composition of precipitation and the influence of evaporation, as well as shifts

  12. High-resolution coproecology: using coprolites to reconstruct the habits and habitats of New Zealand's extinct upland moa (Megalapteryx didinus).

    PubMed

    Wood, Jamie R; Wilmshurst, Janet M; Wagstaff, Steven J; Worthy, Trevor H; Rawlence, Nicolas J; Cooper, Alan

    2012-01-01

    Knowledge about the diet and ecology of extinct herbivores has important implications for understanding the evolution of plant defence structures, establishing the influences of herbivory on past plant community structure and composition, and identifying pollination and seed dispersal syndromes. The flightless ratite moa (Aves: Dinornithiformes) were New Zealand's largest herbivores prior to their extinction soon after initial human settlement. Here we contribute to the knowledge of moa diet and ecology by reporting the results of a multidisciplinary study of 35 coprolites from a subalpine cave (Euphrates Cave) on the South Island of New Zealand. Ancient DNA analysis and radiocarbon dating revealed the coprolites were deposited by the extinct upland moa (Megalapteryx didinus), and span from at least 6,368±31 until 694±30 (14)C years BP; the approximate time of their extinction. Using pollen, plant macrofossil, and ancient DNA analyses, we identified at least 67 plant taxa from the coprolites, including the first evidence that moa fed on the nectar-rich flowers of New Zealand flax (Phormium) and tree fuchsia (Fuchsia excorticata). The plant assemblage from the coprolites reflects a highly-generalist feeding ecology for upland moa, including browsing and grazing across the full range of locally available habitats (spanning southern beech (Nothofagus) forest to tussock (Chionochloa) grassland). Intact seeds in the coprolites indicate that upland moa may have been important dispersal agents for several plant taxa. Plant taxa with putative anti-browse adaptations were also identified in the coprolites. Clusters of coprolites (based on pollen assemblages, moa haplotypes, and radiocarbon dates), probably reflect specimens deposited at the same time by individual birds, and reveal the necessity of suitably large sample sizes in coprolite studies to overcome potential biases in diet interpretation.

  13. Millennial-scale variability in Southern Hemisphere westerly wind activity over the last 5000 years in SW Patagonia

    NASA Astrophysics Data System (ADS)

    Moreno, P. I.; François, J. P.; Villa-Martínez, R. P.; Moy, C. M.

    2009-01-01

    Here we report results from a high-resolution palynological record and stratigraphic/geochronologic data related to a Neoglacial event in Torres del Paine National Park, southern Chile (51°S, 71°W), to investigate climatic variations in Southwest Patagonia during the last 5000 years. The record reveals a stepwise expansion of Nothofagus-dominated woodlands and forests with discrete pulses at 4400, 2900, 1300, and 570 cal yr BP. Superimposed upon this trend we identify a relative opening of the woodlands between 4100-2900 and 2300-1300 cal yr BP. Closed-canopy forests dominated the landscape between 570-60 cal yr BP, followed by a rapid decline at the end of the 19th century that coincided with intense fire activity and the appearance of Rumex cf. acetocella, an exotic species introduced by European settlers. We interpret these changes as variations in the intensity and/or position of the southern margin of the westerly winds, which culminated with a net eastward shift of the forest-steppe ecotone during the Little Ice Age. We propose that millennial-scale changes in either the latitudinal position and/or the overall strength of the southern westerlies may be responsible for vegetation changes, fire occurrence, and the dynamic behavior of Patagonian glaciers during the last 5000 years. Because the modern maximum in near-surface wind velocities and precipitation is located between 48° and 50°S, we suggest that the core of the southern westerlies may have achieved this modern position ˜570 years ago.

  14. Antarctotrechus balli sp. n. (Carabidae, Trechini): the first ground beetle from Antarctica

    PubMed Central

    Ashworth, Allan C; Erwin, Terry L.

    2016-01-01

    Abstract Fossil elytra of a small trechine carabid are reported from the Oliver Bluffs on the Beardmore Glacier at lat. 85°S. They were compared with counterparts from the extant genera Trechisibus, Tasmanorites, Oxytrechus and Pseudocnides. The fossils share some characters but are sufficiently different to be described as a new genus and species. We named the new species Antarctotrechus balli in honour of George E. Ball who made major contributions to the study of carabids through his own research and the training of students while at the University of Alberta, Edmonton, Alberta, Canada. The closest extant relatives to the extinct Antarctotrechus balli are species of Trechisibus, which inhabit South America, the Falkland Islands and South Georgia, and Tasmanorites, which inhabit Tasmania, Australia. Plant fossils associated with Antarctotrechus balli included Nothofagus (southern beech), Ranunculus (buttercup), moss mats and cushion plants that were part of a tundra biome. Collectively, the stratigraphic relationships and the growth characteristics of the fossil plants indicate that Antarctotrechus balli inhabited the sparsely-vegetated banks of a stream that was part of an outwash plain at the head of a fjord in the Transantarctic Mountains. Other insects represented by fossils in the tundra biome include a listroderine weevil and a cyclorrhaphan fly. The age of the fossils, based on comparison of associated pollen with 40Ar/39Ar dated pollen assemblages from the McMurdo Dry Valleys, is probably Early to Mid-Miocene in the range 14–20 Ma. The tundra biome, including Antarctotrechus balli, became extinct in the interior of Antarctica about 14 Ma and on the margins of the continent by 10–13 Ma. Antarctotrechus balli confirms that trechines were once widely distributed in Gondwana. For Antarctotrechus balli and other elements of the tundra biome it appears they continued to inhabit a warmer Antarctica for many millions of years after rifting of Tasmania (45 Ma

  15. Impacts of solar ultraviolet-B radiation on terrestrial ecosystems of Tierra del Fuego (southern Argentina). An overview of recent progress.

    PubMed

    Ballaré, C L; Rousseau, M C; Searles, P S; Zaller, J G; Giordano, C V; Robson, T M; Caldwell, M M; Sala, O E; Scopel, A L

    2001-09-01

    The southern part of Tierra del Fuego, in the southernmost tip of South America, is covered by dense Nothofagus spp. forests and Sphagnum-dominated peat bogs, which are subjected to the influence of ozone depletion and to increased levels of solar ultraviolet-B radiation (UV-B). Over the last 5 years we have studied some of the biological impacts of solar UV-B on natural ecosystems of this region. We have addressed two general problems: (i) do the fluctuations in UV-B levels under the influence of the Antarctic ozone 'hole' have any measurable biological impact, and (ii) what are the long-term effects of solar (ambient) UV-B on the Tierra del Fuego ecosystems? In this paper, we provide an overview of the progress made during the first 4 years of the project. We highlight and discuss the following results: (1) ambient UV-B has subtle but significant inhibitory effects on the growth of herbaceous and graminoid species of this region (growth reduction < or = 12%), whereas no consistent inhibitory effects could be detected in woody perennials; (2) in the species investigated in greatest detail, Gunnera magellanica, the inhibitory effect of solar UV-B is accompanied by increased levels of DNA damage in leaf tissue, and the DNA damage density in the early spring is clearly correlated with the dose of weighted UV-B measured at ground level; (3) the herbaceous species investigated thus far show little or no acclimation responses to ambient UV-B such as increased sunscreen levels and DNA repair capacity; and (4) ambient UV-B has significant effects on heterotrophic organisms, included marked inhibitory effects on insect herbivory. The results from the experiments summarized in this review clearly indicate that UV-B influences several potentially important processes and ecological interactions in the terrestrial ecosystems of Tierra del Fuego.

  16. Radiation of the Australian flora: what can comparisons of molecular phylogenies across multiple taxa tell us about the evolution of diversity in present-day communities?

    PubMed Central

    Crisp, Mike; Cook, Lyn; Steane, Dorothy

    2004-01-01

    The Australian fossil record shows that from ca. 25 Myr ago, the aseasonal-wet biome (rainforest and wet heath) gave way to the unique Australian sclerophyll biomes dominated by eucalypts, acacias and casuarinas. This transition coincided with tectonic isolation of Australia, leading to cooler, drier, more seasonal climates. From 3 Myr ago, aridification caused rapid opening of the central Australian arid zone. Molecular phylogenies with dated nodes have provided new perspectives on how these events could have affected the evolution of the Australian flora. During the Mid-Cenozoic (25-10 Myr ago) period of climatic change, there were rapid radiations in sclerophyll taxa, such as Banksia, eucalypts, pea-flowered legumes and Allocasuarina. At the same time, taxa restricted to the aseasonal-wet biome (Nothofagus, Podocarpaceae and Araucariaceae) did not radiate or were depleted by extinction. During the Pliocene aridification, two Eremean biome taxa (Lepidium and Chenopodiaceae) radiated rapidly after dispersing into Australia from overseas. It is clear that the biomes have different histories. Lineages in the aseasonal-wet biome are species poor, with sister taxa that are species rich, either outside Australia or in the sclerophyll biomes. In conjunction with the fossil record, this indicates depletion of the Australian aseasonal-wet biome from the Mid-Cenozoic. In the sclerophyll biomes, there have been multiple exchanges between the southwest and southeast, rather than single large endemic radiations after a vicariance event. There is need for rigorous molecular phylogenetic studies so that additional questions can be addressed, such as how interactions between biomes may have driven the speciation process during radiations. New studies should include the hitherto neglected monsoonal tropics. PMID:15519972

  17. Emission factors for PM2.5, CO, CO2, NOx, SO2 and particle size distributions from the combustion of wood species using a new controlled combustion chamber 3CE.

    PubMed

    Cereceda-Balic, Francisco; Toledo, Mario; Vidal, Victor; Guerrero, Fabian; Diaz-Robles, Luis A; Petit-Breuilh, Ximena; Lapuerta, Magin

    2017-04-15

    The objective of this research was to determine emission factors (EF) for particulate matter (PM2.5), combustion gases and particle size distribution generated by the combustion of Eucalyptus globulus (EG), Nothofagus obliqua (NO), both hardwoods, and Pinus radiata (PR), softwood, using a controlled combustion chamber (3CE). Additionally, the contribution of the different emissions stages associated with the combustion of these wood samples was also determined. Combustion experiments were performed using shaving size dried wood (0% humidity). The emission samples were collected with a tedlar bag and sampling cartridges containing quartz fiber filters. High reproducibility was achieved between experiment repetitions (CV<10%, n=3). The EF for PM2.5 was 1.06gkg(-1) for EG, 1.33gkg(-1) for NO, and 0.84gkg(-1) for PR. Using a laser aerosol spectrometer (0.25-34μm), the contribution of particle emissions (PM2.5) in each stage of emission process (SEP) was sampled in real time. Particle size of 0.265μm were predominant during all stages, and the percentages emitted were PR (33%), EG (29%), and NO (21%). The distributions of EF for PM2.5 in pre-ignition, flame and smoldering stage varied from predominance of the flame stage for PR (77%) to predominance of the smoldering stage for NO (60%). These results prove that flame phase is not the only stage contributing to emissions and on the contrary, pre-ignition and in especial post-combustion smoldering have also very significant contributions. This demonstrates that particle concentrations measured only in stationary state during flame stage may cause underestimation of emissions. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. The Potential of Stomatal Frequency Analysis as a Paleo-Altimeter

    NASA Astrophysics Data System (ADS)

    Kouwenberg, L. L.; McElwain, J. C.

    2005-12-01

    Quantitative estimations of paleo-elevation are invaluable for setting boundary conditions in both orogenic and paleo-climate models. Ideally, these estimates are based on the reconstruction of a physical parameter changing predictably with altitude, independent of latitude or atmospheric circulation patterns. One such parameter is CO2 partial pressure that declines with the decrease in atmospheric pressure over altitude in an entirely predictable manner. The CO2 partial pressure can be estimated through stomatal frequency analysis of fossil leaves, which has been used extensively to generate paleo-CO2 reconstructions throughout the Phanerozoic. If sea-level atmospheric CO2 levels are known, either through stomatal frequency analysis of sea-level floras or alternative methods, altitude can theoretically be estimated by determining the difference in CO2 partial pressure between sea level and a flora from unknown higher elevation. Thus, stomatal analysis of fossil leaves should be applicable to reconstruct paleo-elevation, and in this study we validate the potential of different tree species, both angiosperm and conifer, as paleo-altimeters by (1) developing calibration curves of stomatal frequency vs altitude in modern trees, (2) estimating prediction errors by predicting known modern elevations, and (3) discuss the influence of altitude-dependent environmental factors, other than CO2, on the stomatal frequency that might have the capacity to mask the CO2 partial pressure signal. To test the global applicability of this method in different climate regimes and latitudes, intrageneric and interspecific variability in elevational response is assessed for a tropical everwet ( Quercus costaricensis, Q. copeyensis), temperate winterwet ( Quercus kelloggii) and a temperate everwet climate ( Nothofagus solandri (var. cliffortioides)). Finally, we hope to present the first stomata-based Tertiary paleo-elevation estimates for the western US and compare these to existing

  19. Pollen sequence from the Chilean Lake District during the Llanquihue glaciation in marine Oxygen Isotope Stages 4-2

    NASA Astrophysics Data System (ADS)

    Heusser, Calvin J.; Lowell, Thomas V.; Heusser, Linda E.; Moreira M., Andrés; Moreira M., Simón

    2000-02-01

    Pollen stratigraphy of a core taken from a fen at Fundo Nueva Braunau (40°17.49S, 73°04.83W), situated 2 km beyond the western border of Llanquihue-age glacial drift, spans an age range from an estimated 60 000-70 000 BP to about 14 000 14C yr BP (marine Oxygen Isotope Stages 4-2). The location at present is in the contact zone of Valdivian Evergreen Forest and Lowland Deciduous Beech Forest. Early and late in the pollen record, as indicated by assemblages of southern beech (Nothofagus dombeyi type) and grass (Gramineae), the site was located in Subantarctic Parkland. Intervening assemblages represent expansion of Valdivian-North Patagonian Evergreen Forest (> 49 355 to about 40 000 14C yr BP) and North Patagonian Evergreen Forest-Subantarctic Parkland (approximately 40 000 to 30 000 14C yr BP).Climate over the time span was under the storm regime of the Southern Westerlies and apparently uninterruptedly wet. When Subantarctic Parkland expanded, cold conditions with summer temperatures estimated at 8-9°C (7°C lower than present) resulted in episodes of glacier maxima. Climate moderated during the period of forest expansion, at which time glaciers were in a state of recession. Contrasting with the continuously wet climate of the Lake District for the period of record, climate in semi-arid-arid, subtropical Chile underwent extended intervals of precipitation. Data from both the terrestrial and marine realm implicate the Southern Westerlies as the cause of intensified storm activity at lower latitudes.

  20. Friis Hills glacial history: an international collaboration to examine Miocene climate in Antarctica

    NASA Astrophysics Data System (ADS)

    Halberstadt, A. R. W.; Kowalewski, D. E.

    2016-12-01

    The Friis Hills, Antarctica (western McMurdo Dry Valleys) contain unique, well-preserved records of Miocene climate. These terrestrial deposits hold geomorphic clues for deciphering the glacial history in a region directly adjacent to the East Antarctic Ice Sheet. Stacked till sheets, interbedded with lake sediments and non-glacial deposits, reveal a complex history of ice flow and erosion throughout multiple glacial-interglacial cycles (Lewis and Ashworth, 2015). Fossiliferous beds containing Nothofagus, diatoms, algal cells, pollen, insects, and mosses provide past climatological constraints. The Friis Hills sustained multiple alpine glaciations as well as full ice-sheet development, recording glacial drainage reorganization and evidence of previous ice configurations that possibly overrode the Transantarctic Mountains (Lewis and Ashworth, 2015) exposing only scattered nunataks (i.e. a portion of Friis Hills). Lack of chronological control has previously hindered efforts to link the Friis Hills glacial history with regional context; a tephra deposit at the base of the glacial drifts currently provides a single age constraint within the drift deposits. To build upon previous studies, an international collaboration between the USAP, Antarctic New Zealand, and the Italian Antarctic community proposes to core a paleo-lake in the center of the Friis Hills in November 2016, thereby acquiring one of the oldest continuous sedimentological records within the McMurdo Dry Valleys. Here we report discoveries from this year's fieldwork, and reconstruct paleoenvironment at the periphery of the East Antarctic Ice Sheet for the mid-early Miocene, a critical time when marine isotopic records indicate dramatic ice fluctuations. Ash within the sediment core stratigraphy will provide a more robust chronology for the region, and will also suggest possible outcrop locations of corresponding ash deposits to pursue while in the field. We anticipate that the Friis Hills stratigraphy will

  1. Succession of ground-dwelling beetle assemblages after fire in three habitat types in the Andean forest of NW Patagonia, Argentina.

    PubMed

    Sasal, Yamila; Raffaele, Estela; Farji-Brener, Alejandro G

    2010-01-01

    Wildfires are one of the major disturbances in the dynamics of forests and shrublands. However, little is known about their effects on insect communities that contribute to faunal biodiversity and play key roles in the ecosystem's dynamics. An intense and widespread fire occurred in 1999 in the Nahuel Huapi National Park in the Andean forest in northern Patagonia, Argentina. This fire affected adjacent, but different, habitat types. After the fire, beetle abundance, species richness and assemblage composition were compared among three habitats that were structurally different before the fire. These habitats were: 1) evergreen forest dominated by Nothofagus dombeyi (Mirb.) Oerst. (Fagales: Nothofagaceae), 2) a mixed forest of the evergreen conifer Austrocedrus chilensis (D. Don) Pic. Serm. and Bizzarri (Pinales: Cupressaceae) and N. dombeyi and 3) a shrubland with a diverse community of shrub species. The relationship between beetle diversity and vegetation structure was investigated over three consecutive years. Ground beetles were collected by pitfall traps, and plant species richness, vegetation cover, and height were measured. Beetle communities varied more over years between habitats during the early regeneration after fire. There was a shift in beetle assemblage composition with time after the fire in all habitat types, probably due to similar colonization rates and microclimatic conditions. Therefore, beetle succession was more influenced by recolonization and survivorship, accompanied by climatic conditions and recovery rate of plant communities over time, than it was influenced by pre-fire habitat conditions. These results suggest that in NW Patagonia, wildfire can have a substantial, short-term impact on beetle abundance and species composition. The pre-fire conditions of each habitat type determined the structure of post-fire communities of plants but not beetle assemblages. Wildfires produce simplification and homogenization of habitat types, and this

  2. Genetics of sprouting: effects of long-term persistence in fire-prone ecosystems.

    PubMed

    Premoli, Andrea C; Steinke, Lina

    2008-09-01

    Fire functional traits (postfire resprouting and seeding) are considered to be adaptations for persisting in fire-prone environments. Although ecological and evolutionary consequences of sprouting have been extensively discussed, within-species genetic variability and structure are unknown. Here we report levels and distribution patterns of genetic polymorphisms in postfire stands of the predominant sprouter Nothofagus antarctica. Fresh foliage of 50 individuals was collected following a spatially explicit sampling design for isozyme analysis from two replicates of each of four habitat types inhabited by the species in northwestern Patagonia, Argentina: matorral, high elevation, forest, and temporally flooded basins. Average polymorphism per population ranged from 44% to 78% and mean gene diversity per site H(S )varied from 0.187 to 0.274. These results show that sprouter populations hold considerable genetic variation. Significant genetic structure over short distances (< 50 m) was found at all locations. Ancient fine-scale genetic structure is preserved by occasional seedling establishment that results in high co-ancestry coefficients. Sprouter populations growing in suboptimal habitats such as matorral, high elevation or basins consist of pairs of heterozygous genets that occur at larger spatial scales as a result of micro-environmental heterogeneity and/or local competition between near neighbour genotypes. In contrast, homozygous pairs of individuals for distinct isozyme loci occurred at larger spatial scales in forest stands. This indicates that biparental inbreeding due to local propagule establishment may take place to some extent in sprouters growing under favourable conditions. Our results show that sprouters follow a long-lasting genet persistence strategy which most probably is selected under unpredictable disturbance regimes, such as fire.

  3. Foraging behaviour of the exotic wasp Vespula germanica (Hymenoptera: Vespidae) on a native caterpillar defoliator.

    PubMed

    Pietrantuono, A L; Moreyra, S; Lozada, M

    2017-09-19

    Vespula germanica is a social wasp and an opportunistic predator. While foraging, these wasps learn and integrate different kinds of cues. They have successfully invaded many parts of the world, including native Nothofagus and Lophozonia forests located in the Andean-Patagonian region, where they forage on native arthropods. Perzelia arda, a lepidopteron defoliator of Lophozonia obliqua, uses the foliage to hide in and feed on. The purpose of this work is to study whether V. germanica use olfactory cues when foraging on P. arda. To do this, we used a Y-tube olfactometer and established three treatments to compare pairs of all combinations of stimuli (larvae, leaves with larval traces, and leaves without larval traces) and controls. Data were analysed via two developed models that showed decisions made by V. germanica and allowed to establish a scale of preferences between the stimuli. The analysis demonstrates that V. germanica wasps choose P. arda as larval prey and are capable of discriminating between the offered stimuli (deviance information criterion (DIC) null model = 873.97; DIC simple model = 84.5, n = 152). According to the preference scale, V. germanica preferred leaves with traces of larvae, suggesting its ability to associate these traces with the presence of the prey. This may be because, under natural conditions, larvae are never exposed outside their shelters of leaves and therefore V. germanica uses indirect signals. The presence of V. germanica foraging on P. arda highlights the flexible foraging behaviour of this wasp which may also act as a positive biological control, reducing lepidopteran populations.

  4. Interactive effects of atmospheric carbon dioxide and leaf nitrogen concentration on canopy light use efficiency: a modeling analysis.

    PubMed

    Medlyn, B. E.

    1996-01-01

    Potential increases in plant productivity in response to increasing atmospheric CO(2) concentration are likely to be constrained by nutrient limitations. However, the interactive effects of nitrogen nutrition and CO(2) concentration on growth are difficult to define because both factors affect several aspects of growth, including photosynthesis, respiration, and leaf area. By expressing growth as a product of light intercepted and light use efficiency (epsilon), it is possible to decouple the effects of nutrient availability and CO(2) concentration on photosynthetic rates from their effects on other aspects of plant growth. I used measured responses of leaf photosynthesis to leaf nitrogen (N) content and CO(2) concentration to parameterize a model of canopy radiation absorption and photosynthesis, and then used the model to estimate the response of epsilon to elevated CO(2) concentration for Pinus radiata D. Don, Nothofagus fusca (Hook. f.) Ørst. and Eucalyptus grandis W. Hill ex Maiden. Down-regulation of photosynthesis at elevated CO(2) was represented as a reduction in either leaf N content or leaf Rubisco activity. The response of epsilon to elevated CO(2), which differed among the three species, was analyzed in terms of the underlying relationships between leaf photosynthesis and leaf N content. The response was independent of leaf N content when photosynthesis was down-regulated to the same extent at low and high leaf N content. Interactive effects of N availability and CO(2) on growth are thus likely to be the result of either differences in down-regulation of photosynthesis at low and high N availability or interactive effects of CO(2) and N availability on other aspects of plant growth.

  5. High-Resolution Coproecology: Using Coprolites to Reconstruct the Habits and Habitats of New Zealand’s Extinct Upland Moa (Megalapteryx didinus)

    PubMed Central

    Wood, Jamie R.; Wilmshurst, Janet M.; Wagstaff, Steven J.; Worthy, Trevor H.; Rawlence, Nicolas J.; Cooper, Alan

    2012-01-01

    Knowledge about the diet and ecology of extinct herbivores has important implications for understanding the evolution of plant defence structures, establishing the influences of herbivory on past plant community structure and composition, and identifying pollination and seed dispersal syndromes. The flightless ratite moa (Aves: Dinornithiformes) were New Zealand’s largest herbivores prior to their extinction soon after initial human settlement. Here we contribute to the knowledge of moa diet and ecology by reporting the results of a multidisciplinary study of 35 coprolites from a subalpine cave (Euphrates Cave) on the South Island of New Zealand. Ancient DNA analysis and radiocarbon dating revealed the coprolites were deposited by the extinct upland moa (Megalapteryx didinus), and span from at least 6,368±31 until 694±30 14C years BP; the approximate time of their extinction. Using pollen, plant macrofossil, and ancient DNA analyses, we identified at least 67 plant taxa from the coprolites, including the first evidence that moa fed on the nectar-rich flowers of New Zealand flax (Phormium) and tree fuchsia (Fuchsia excorticata). The plant assemblage from the coprolites reflects a highly-generalist feeding ecology for upland moa, including browsing and grazing across the full range of locally available habitats (spanning southern beech (Nothofagus) forest to tussock (Chionochloa) grassland). Intact seeds in the coprolites indicate that upland moa may have been important dispersal agents for several plant taxa. Plant taxa with putative anti-browse adaptations were also identified in the coprolites. Clusters of coprolites (based on pollen assemblages, moa haplotypes, and radiocarbon dates), probably reflect specimens deposited at the same time by individual birds, and reveal the necessity of suitably large sample sizes in coprolite studies to overcome potential biases in diet interpretation. PMID:22768206

  6. Predicted responses of invasive mammal communities to climate-related changes in mast frequency in forest ecosystems.

    PubMed

    Tompkins, Daniel M; Byrom, Andrea E; Pech, Roger P

    2013-07-01

    Predicting the dynamics and impacts of multiple invasive species can be complex because ecological relationships, which occur among several trophic levels, are often incompletely understood. Further, the complexity of these trophic relationships exacerbates our inability to predict climate change effects on invaded ecosystems. We explore the hypothesis that interactions between two global change drivers, invasive vertebrates and climate change, will potentially make matters worse for native biodiversity. In New Zealand beech (Nothofagus spp.) forests, a highly irruptive invasive mammal community is driven by multi-annual resource pulses of beech seed (masting). Because mast frequency is predicted to increase with climate change, we use this as a model system to explore the extent to which such effects may influence invasive vertebrate communities, and the implications of such interactions for native biodiversity and its management. We build on an established model of trophic interactions in the system, combining it with a logistic probability mast function, the parameters of which were altered to simulate either contemporary conditions or conditions of more or less frequent masting. The model predicts that increased mast frequency will lead to populations of a top predator (the stoat) and a mesopredator (the ship rat) becoming less irruptive and being maintained at appreciably higher average abundances in this forest type. In addition, the ability of both current and in-development management approaches to suppress invasive mammals is predicted to be compromised. Because invasive mammals are key drivers of native fauna extinction in New Zealand, with the additional loss of associated functions such as pollination and seed dispersal, these predictions imply potentially serious adverse impacts of climate change for the conservation of biodiversity and ecosystem function. Our study also highlights the importance of long-term monitoring data for assessing and managing

  7. Low but structured chloroplast diversity in Atherosperma moschatum (Atherospermataceae) suggests bottlenecks in response to the Pleistocene glacials

    PubMed Central

    Worth, James R. P.; Marthick, James R.; Jordan, Gregory J.; Vaillancourt, René E.

    2011-01-01

    Background and Aims The cool temperate rainforests of Australia were much reduced in range during the cold and dry glacial periods, although genetic evidence indicates that two key rainforest species, Nothofagus cunninghamii and Tasmannia lanceolata, survived within multiple locations and underwent only local range expansions at the end of the Last Glacial. To better understand the glacial response of a co-occurring but wind-dispersed and less cold-tolerant rainforest tree species, Atherosperma moschatum, a chloroplast phylogeographic study was undertaken. Methods A total of 3294 bp of chloroplast DNA sequence was obtained for 155 samples collected from across the species' range. Key Results The distribution of six haplotypes observed in A. moschatum was geographically structured with an inferred ancestral haplotype restricted to Tasmania, while three non-overlapping and endemic haplotypes were found on the mainland of south-eastern Australia. Last glacial refugia for A. moschatum are likely to have occurred in at least one location in western Tasmania and in Victoria and within at least two locations in the Great Dividing Range of New South Wales. Nucleotide diversity of A. moschatum was lower (π = 0·00021) than either N. cunninghamii (0·00101) or T. lanceolata (0·00073), and was amongst the lowest recorded for any tree species. Conclusions This study provides evidence for past bottlenecks having impacted the chloroplast diversity of A. moschatum as a result of the species narrower climatic niche during glacials. This hypothesis is supported by the star-like haplotype network and similar estimated rates of chloroplast DNA substitution for A. moschatum and the two more cold tolerant and co-occurring species that have higher chloroplast diversity, N. cunninghamii and T. lanceolata. PMID:21856633

  8. Vegetation and climate in Southern Hemisphere mid-latitudes since 210 ka: new insights from marine and terrestrial pollen records from New Zealand

    NASA Astrophysics Data System (ADS)

    Ryan, M. T.; Dunbar, G. B.; Vandergoes, M. J.; Neil, H. L.; Hannah, M. J.; Newnham, R. M.; Bostock, H.; Alloway, B. V.

    2012-08-01

    Paleo-vegetation records developed from marine sedimentary sequences offer considerable potential for examining changes in terrestrial climate beyond the range of 14C dating because they can be independently dated by δ18O stratigraphy. Here we present the first pollen record of vegetation from a marine core site in the Tasman Sea, TAN0513-14 (42°18'S, 169°53'E), ˜110 km west of New Zealand's South Island. An independent chronology provided by correlating the Globigerina bulloides δ18O record at TAN0513-14 to a global isotope stack shows that the record extends back to 210 ka. Glacial to interglacial changes in palynomorph content are characterised by shrub and podocarp-broadleaf forest taxa respectively and are correlated with similar changes in the ca 150 kyr-long terrestrial pollen record from Okarito Pakihi (bog), 110 km to the south southeast. Both records are placed on the same timescale by matching variations in Dacrydium cupressinum and Fuscospora between sites, with a unique tie point provided by the ca 25.4 ka Kawakawa Tephra. Our Southern Hemisphere mid-latitude vegetation records show forest extent is greatest during periods of low ice volume, high mean annual sea surface temperature (MASST) and anti-phased with local insolation intensity. However, there are several features not attributable to changes in mean annual temperature. First, a fundamental change in forest composition occurred at Termination II (TII), with a loss of southern beech (Nothofagus) from the study area. Second, the amplitude of MASST change through MIS 5 is not reflected in corresponding changes in forest extent, suggesting other feature(s) of regional climate (seasonality, frostiness, ice cover) exert important controls over vegetation patterns at these latitudes.

  9. Antarctotrechus balli sp. n. (Carabidae, Trechini): the first ground beetle from Antarctica.

    PubMed

    Ashworth, Allan C; Erwin, Terry L

    2016-01-01

    Fossil elytra of a small trechine carabid are reported from the Oliver Bluffs on the Beardmore Glacier at lat. 85°S. They were compared with counterparts from the extant genera Trechisibus, Tasmanorites, Oxytrechus and Pseudocnides. The fossils share some characters but are sufficiently different to be described as a new genus and species. We named the new species Antarctotrechus balli in honour of George E. Ball who made major contributions to the study of carabids through his own research and the training of students while at the University of Alberta, Edmonton, Alberta, Canada. The closest extant relatives to the extinct Antarctotrechus balli are species of Trechisibus, which inhabit South America, the Falkland Islands and South Georgia, and Tasmanorites, which inhabit Tasmania, Australia. Plant fossils associated with Antarctotrechus balli included Nothofagus (southern beech), Ranunculus (buttercup), moss mats and cushion plants that were part of a tundra biome. Collectively, the stratigraphic relationships and the growth characteristics of the fossil plants indicate that Antarctotrechus balli inhabited the sparsely-vegetated banks of a stream that was part of an outwash plain at the head of a fjord in the Transantarctic Mountains. Other insects represented by fossils in the tundra biome include a listroderine weevil and a cyclorrhaphan fly. The age of the fossils, based on comparison of associated pollen with (40)Ar/(39)Ar dated pollen assemblages from the McMurdo Dry Valleys, is probably Early to Mid-Miocene in the range 14-20 Ma. The tundra biome, including Antarctotrechus balli, became extinct in the interior of Antarctica about 14 Ma and on the margins of the continent by 10-13 Ma. Antarctotrechus balli confirms that trechines were once widely distributed in Gondwana. For Antarctotrechus balli and other elements of the tundra biome it appears they continued to inhabit a warmer Antarctica for many millions of years after rifting of Tasmania (45 Ma) and

  10. Succession of Ground-Dwelling Beetle Assemblages After Fire in Three Habitat Types in the Andean Forest of NW Patagonia, Argentina

    PubMed Central

    Sasal, Yamila; Raffaele, Estela; Farji-Brener, Alejandro G.

    2010-01-01

    Wildfires are one of the major disturbances in the dynamics of forests and shrublands. However, little is known about their effects on insect communities that contribute to faunal biodiversity and play key roles in the ecosystem's dynamics. An intense and widespread fire occurred in 1999 in the Nahuel Huapi National Park in the Andean forest in northern Patagonia, Argentina. This fire affected adjacent, but different, habitat types. After the fire, beetle abundance, species richness and assemblage composition were compared among three habitats that were structurally different before the fire. These habitats were: 1) evergreen forest dominated by Nothofagus dombeyi (Mirb.) Oerst. (Fagales: Nothofagaceae), 2) a mixed forest of the evergreen conifer Austrocedrus chilensis (D. Don) Pic. Serm. and Bizzarri (Pinales: Cupressaceae) and N. dombeyi and 3) a shrubland with a diverse community of shrub species. The relationship between beetle diversity and vegetation structure was investigated over three consecutive years. Ground beetles were collected by pitfall traps, and plant species richness, vegetation cover, and height were measured. Beetle communities varied more over years between habitats during the early regeneration after fire. There was a shift in beetle assemblage composition with time after the fire in all habitat types, probably due to similar colonization rates and microclimatic conditions. Therefore, beetle succession was more influenced by recolonization and survivorship, accompanied by climatic conditions and recovery rate of plant communities over time, than it was influenced by pre-fire habitat conditions. These results suggest that in NW Patagonia, wildfire can have a substantial, short-term impact on beetle abundance and species composition. The pre-fire conditions of each habitat type determined the structure of post-fire communities of plants but not beetle assemblages. Wildfires produce simplification and homogenization of habitat types, and this

  11. Earth Observations taken by the Expedition 13 crew

    NASA Image and Video Library

    2006-08-27

    ISS013-E-71468 (27 Aug. 2006) --- Bajo Nuevo Reef in the western Caribbean Sea is featured in this image photographed by an Expedition 13 crewmember on the International Space Station. The Bajo Nuevo reef is approximately 26 kilometers long, comprising two separate U-shaped cays, with only tiny sandy islands associated with them. This detailed view reveals small, low islands that fringe the upwind side (image right) of the lagoon. These islands seem dwarfed by wave swells, which almost appear to wash over them. The clearest feature is the broad pattern of swells which show two slightly different orientations, producing a tightly crossed pattern. These swells are oriented transverse to the wind direction and were probably set in motion by two different storms hundreds of kilometers east of the reef. A single irregular line of light color--also suggestive of surface oil--traces a path along the south side of the lagoon.

  12. Earth Observations taken by the Expedition 13 crew

    NASA Image and Video Library

    2006-08-27

    ISS013-E-71465 (27 Aug. 2006) --- Bajo Nuevo Reef in the western Caribbean Sea is featured in this image photographed by an Expedition 13 crewmember on the International Space Station. The Bajo Nuevo reef is approximately 26 kilometers long, comprising two separate U-shaped cays, with only tiny sandy islands associated with them. The eastern cay, shown in this image, encloses a lagoon. Protected from open-sea swells, the water surface is calmer and some back reef detail is visible within the lagoon. Cloud shadows darken the top left corner. The clearest feature is the broad pattern of swells which show two slightly different orientations, producing a tightly crossed pattern. These swells are oriented transverse to the wind direction and were probably set in motion by two different storms hundreds of kilometers east of the reef. A single irregular line of light color--also suggestive of surface oil--traces a path along the south side of the lagoon.

  13. Hydrogeological investigations in the Pampa of Argentina. [using LANDSAT 1 and Skylab imagery

    NASA Technical Reports Server (NTRS)

    Kruck, W.; Kantor, W.

    1975-01-01

    In large areas of the Argentinian Pampa the salinization of ground water creates water supply difficulties. Investigations of satellite imagery (Landsat-1 and Skylab) which were based on an extensive ground survey revealed that differences in the vegetation cover are closely related to depth and salinity of ground water. Narrow elongated depressions called bajos are often the only indication of fresh ground water. They can be easily detected on the imagery. Due to their high resolution, Skylab photos even allow a quantitative estimation of fresh ground water situated below the bajos. In general however Landsat-1 imagery sufficed for evaluation. In the area of the Rio Tercero a fossil drainage pattern was discovered and in Corrientes province, soil types could be discriminated and compared to the Soil Map of the World.

  14. 3D geometry of growth strata in a fault-propagation fold: insights into space-time evolution of the Crevillente Fault (Abanilla-Alicante sector), Betic Cordillera, Spain

    NASA Astrophysics Data System (ADS)

    Martin-Rojas, I.; Alfaro, P.; Estévez, A.

    2015-07-01

    This work presents a 3D geometric model of growth strata cropping out in a fault-propagation fold associated with the Crevillente Fault (Abanilla-Alicante sector) from the Bajo Segura Basin (eastern Betic Cordillera, southern Spain). The analysis of this 3D model enables us to unravel the along-strike and along-section variations of the growth strata, providing constraints to assess the fold development, and hence, the fault kinematic evolution in space and time. We postulate that the observed along-strike dip variations are related to lateral variation in fault displacement. Along-section variations of the progressive unconformity opening angles indicate greater fault slip in the upper Tortonian-Messinian time span; from the Messinian on, quantitative analysis of the unconformity indicate a constant or lower tectonic activity of the Crevillente Fault (Abanilla-Alicante sector); the minor abundance of striated pebbles in the Pliocene-Quaternary units could be interpreted as a decrease in the stress magnitude and consequently in the tectonic activity of the fault. At a regional scale, comparison of the growth successions cropping out in the northern and southern limits of the Bajo Segura Basin points to a southward migration of deformation in the basin. This means that the Bajo Segura Fault became active after the Crevillente Fault (Abanilla-Alicante sector), for which activity on the latter was probably decreasing according to our data. Consequently, we propose that the seismic hazard at the northern limit of the Bajo Segura Basin should be lower than at the southern limit.

  15. [TEEN MOTHER AND NEWBORN NUTRITIONAL STATUS IN A GROUP OF TEENAGERS OF THE CITY OF MEDELLIN].

    PubMed

    Restrepo-Mesa, Sandra Lucia; Zapata López, Natalia; Parra Sosa, Beatriz Elena; Escudero Vásquez, Luz Estela; Betancur Arrovaye, Laura

    2015-09-01

    Introducción: en los países en vía de desarrollo, entre ellos Colombia, el embarazo adolescente es un problema de salud pública por sus consecuencias sociales, de salud y nutrición para el binomio madre-hijo. Objetivo: evaluar las características demográficas, socioeconómicas, de seguridad alimentaria, de salud y el estado nutricional en un grupo de gestantes adolescentes y sus recién nacidos. Métodos: se realizó un estudio analítico de corte transversal con 294 embarazadas adolescentes en el tercer trimestre de gestación del programa de control prenatal de la Red Pública Hospitalaria de Medellín-Colombia, durante 2011-2012. Se buscó la asociación del índice de masa corporal materno, estado nutritivo del hierro y peso al nacer del neonato con variables explicativas. Resultados: los ingresos económicos mensuales inferiores a un salario mínimo se asociaron con bajo peso materno y con recién nacidos pequeños para la edad gestacional. El bajo peso gestacional se presentó en mayor proporción en las gestantes de 15 años o menos y con una edad ginecológica inferior a cinco años. La prevalencia de anemia fue baja en el primer trimestre y aumentó significativamente al final del embarazo; 90% presentaron reservas inadecuadas de hierro. El bajo peso al nacer se asoció con la presencia de infecciones y el bajo peso materno en el tercer trimestre de gestación. Conclusión: la gestación adolescente es un problema complejo que se asocia con efectos negativos en el estado nutricional, de salud y social de la mujer y su recién nacido.

  16. [CONSUMPTION OF OMEGA- 3 FATTY ACIDS AND DEPRESSIVE SYMPTOMS IN COLLEGE STUDENTS FROM SONORA, MEXICO].

    PubMed

    Rubi Vargas, María; González Lomelí, Daniel; Terrazas Medina, Efraín A; Peralta Peña, Sandra L; Jordán Jinez, Ma Lourdes; Ruiz Paloalto, Ma Laura; Cupul Uicab, Lea A

    2015-10-01

    Introducción: estudios recientes sugieren que los niveles bajos de acidos grasos poliinsaturados omega-3 se relacionan con una mayor prevalencia de depresion; sin embargo, los resultados no son concluyentes. Objetivo: evaluar la asociacion entre el bajo consumo de acidos grasos omega-3 y la presencia de sintomas depresivos en jovenes universitarios del noroeste de Mexico. Métodos: se realizo un estudio transversal en una muestra de 706 universitarios de 18 a 24 anos de edad de ambos sexos. La presencia de sintomatologia depresiva se estimo con la escala de Depresion del Centro de Estudios Epidemiologicos (CES-D) empleando un punto de corte ≥ 24. El consumo semanal de acidos grasos alfalinolenico (ALA) y de eicosapentaenoico (EPA) mas docosahexaenoico (DHA) en mg/g de alimento se estimo por medio de un cuestionario de frecuencia de consumo de alimentos validado para la poblacion mexicana. La asociacion del consumo de omega-3 con la presencia de sintomas depresivos se evaluo con modelos de regresion logistica. Resultados: el 67% de los participantes fueron mujeres; en general, el 16,6% presentaron sintomatologia depresiva. El consumo bajo de ALA y EPA + DHA no se asocio con mayor prevalencia de sintomatologia depresiva antes y despues de ajustar por confusores. En aquellos casos con sintomatologia depresiva, los niveles ALA derivados solo de las nueces fueron significativamente menores. Conclusiones: en esta poblacion no se observo asociacion entre el bajo consumo de acidos grasos omega-3 y la sintomatologia depresiva. La posible asociacion entre el consumo de nueces y la sintomatologia depresiva requiere de mas estudios.

  17. Recent Advances in Maya Studies Using Remotely Sensed Data

    NASA Technical Reports Server (NTRS)

    Sever, Tom; Irwin, Daniel; Arnold, James E. (Technical Monitor)

    2001-01-01

    The Peten region of northern Guatemala is one of the last places on earth where major archeological sites remain to be discovered. It was in this region that the Maya civilization began, flourished, and abruptly disappeared. Remote sensing technology is helping to locate and map ancient Maya sites that are threatened today by accelerating deforestation and looting. Thematic Mapper and IKONOS satellite and airborne Star3i radar data, combined with Global Positioning System (GPS) technology, are successfully detecting ancient Maya features such as cities, roadways, canals, and water reservoirs. Satellite imagery is also being used to map the baJos, which are seasonally flooded swamps that cover over 40% of the land surface. The use of bajos for farming has been a source of debate within the professional community for many years. But the recent detection and verification of cultural features within the bajo system by our research team are providing conclusive evidence that the ancient Maya had adapted well to wetland environments from the earliest times and utilized them until the time of the Maya collapse. The combination of water management and bajo farming is an important resource for the future of the current inhabitants who are experiencing rapid population growth. Remote sensing imagery is also demonstrating that in the Preclassic period (600 BC- AD 250), the Maya had already achieved a high organizational level as evidenced by the construction of massive temples and an elaborate inter-connecting roadway system. Although they experienced several setbacks such as droughts and hurricanes, the Maya nevertheless managed the delicate forest ecosystem successfully for several centuries. However, around AD 800, something happened to the Maya to cause their rapid decline and eventual disappearance from the region. The evidence indicates that at this time there was increased climatic dryness, extensive deforestation, overpopulation, and widespread warfare. This raises a

  18. [In Process Citation].

    PubMed

    Santos, Carla Adriana; Fonseca, Jorge; Carolino, Elisabete; Lopes, Teresa; Sousa Guerreiro, António

    2016-03-25

    Introducción y objetivos: el cobre (Cu) es un oligoelemento muy estudiado, pero poco se sabe de su evolución en los pacientes alimentados por gastrostomía endoscópica (GEP). Pretendemos evaluar la evolución del Cu sérico desde la gastrostomía hasta 12 semanas después de la intervención en estos pacientes alimentados con preparaciones domésticas.  Métodos: realizamos un estudio observacional prospectivo para evaluar el Cu sérico, la albúmina, la transferrina y el índice de masa corporal (IMC) en el momento de la GEP, tras 4 semanas y 12 semanas después de la intervención. Los datos incluyen edad, género, NRS 2002 y enfermedad subyacente: cánceres de cabeza y cuello (CCC) y disfagia neurológica (DN). Después de la intervención, estos pacientes fueron alimentados conpreparaciones domésticas. Resultados: 146 enfermos (89 hombres), entre 21-95 años: CCC-56, DN-90. Valores de Cu entre 42-160 μg/dl (normal: 70-140 μg/dl); normales 89% (n = 130); bajos 11% (n = 16), albúmina baja: 53% (n = 77), transferrina baja: 65% (n = 94), IMC bajo: 53% (n = 78). Después de 4 semanas: valores normales de Cu en 93% y bajos en 7%, albúmina baja en 34%, transferrina baja en 52%. Tras 12 semanas: valores normales de Cu en 95% y bajos en 5%, albúmina baja en 25%, transferrina baja en 32%. No encontramos diferencias significativas en el Cusérico cuando se compara edad, género, enfermedad subyacente, IMC, albúmina y transferrina. Conclusiones: la mayoría de los enfermos presentan Cu sérico normal en el momento de la gastrostomía. Para los enfermos con Cu sérico bajo antes del procedimiento, la alimentación con preparaciones domésticas parece suficiente para su normalización progresiva.

  19. Applicability of the visceral adiposity index (VAI) in predicting components of metabolic syndrome in young adults.

    PubMed

    Schuster, Jéssica; Vogel, Patrícia; Eckhardt, Cristiane; Morelo, Simone Dal Bosco

    2014-10-01

    Introducción: El síndrome metabólico (SM) es uno de los principales factores de riesgo de enfermedades cardiovasculares (ECV), y la identificación de sus componentes en los adultos jóvenes puede constituir una importante herramienta de prevención. Objetivo: Analizar la aplicabilidad del Visceral Adiposity Index (VAI) para la predicción de componentes del SM en adultos jóvenes. Métodos: Estudio transversal con 444 individuos, edad 25,6 ± 6,5, 77,7% del sexo femenino. Se obtuvieron datos sobre el peso, talla, circunferencia de cintura (CC), el porcentaje de grasa corporal (%GC), glucemia, triglicéridos (TG), colesterol total (CT), colesterol HDL (HDL-c), colesterol LDL (LDL-c), y la presión arterial (PA), así como información sobre sus estilos de vida. Se calculó Índice de Masa Corporal (IMC), la proporción de cintura a la altura (PCA) y VAI. Mediciones de adiposidad se compararon con los componentes del SM, y por VAI, se determinó la capacidad predictiva de ocurrencia de los componentes de SM y el área a bajo la curva ROC. Resultados: VAI se correlaciona a la glucosa (r= 0,136), HDL-c (r=-436) y TG (r=0,825) en las mujeres y entre los hombres, se correlaciona a la glucosa (r=0,258), HDL-c (r=-0,550), TG (r=0,897), y la PAD (r= 0,290). Un aumento de VAI se asoció a un mayor riesgo de obesidad abdominal (OR=1,86), hipertrigliceridemia (OR=30,74), y bajo HDL-c (OR=3,95). Entre los indicadores de obesidad, VAI presentó una mayor área bajo la curva de aumento de triglicéridos y bajos niveles de HDL-c. Conclusión: VAI presentó una asociación a los componentes del SM en hombres, y em mujeres con un mayor riesgo de obesidad abdominal, hipertrigliceridemia y bajos niveles de HDL-c, demostrando ser un buen predictor de componentes de SM, incluso entre adultos jóvenes sanos.

  20. Active and explorative individuals are often restless and excluded from studies measuring resting metabolic rate: Do alternative metabolic rate measures offer a solution?

    PubMed

    Jäger, Jörg; Schradin, Carsten; Pillay, Neville; Rimbach, Rebecca

    2017-05-15

    It has often been proposed that bolder, more explorative or more active individuals also have a higher resting metabolic rate (RMR), indicating metabolic costs of these personality types. However, such individuals might often be restless and thus excluded from RMR datasets, leading to a significant sampling bias. We tested (1) whether such a bias occurs when animals are measured for a relatively common but short time period of 3h, and if so, (2) whether alternative measures of metabolic rate, that allow the incorporation of non-resting individuals, would reveal associations between metabolism and personality. For this, we studied free-living individuals of the African striped mouse (Rhabdomys pumilio) both during the moist season (N=25 individuals) with high food availability and the dry season (N=48 individuals) with low food availability. We assessed variation in the latency to explore a novel object, and the time spent active and time spent in the centre of a neutral arena. We examined links between personality and (i) RMR and (ii) four alternative metabolic rate (MR) metrics: average MR, highest MR, lowest MR and span of MR. Twenty-nine percent of the measured individuals had to be excluded from our RMR study because they remained restless during respirometry trials. Striped mice showed a behavioural syndrome where fast explorers also spent more time in centre and more time active than slow explorers. Individuals that did not rest during respirometry trials were faster explorers and in the moist season, they were also more active and spent more time in the centre than individuals that rested. We found no relationship between RMR and the behavioural syndrome, which might be due to the exclusion of individuals with a certain behavioural type, leaving a subset of compliant individuals. In the moist season, we found positive relationships between the behavioural syndrome and span of MR and lowest MR. In the dry season, low food availability may mask links between

  1. Transcriptional analysis of phloem-associated cells of potato.

    PubMed

    Lin, Tian; Lashbrook, Coralie C; Cho, Sung Ki; Butler, Nathaniel M; Sharma, Pooja; Muppirala, Usha; Severin, Andrew J; Hannapel, David J

    2015-09-03

    Numerous signal molecules, including proteins and mRNAs, are transported through the architecture of plants via the vascular system. As the connection between leaves and other organs, the petiole and stem are especially important in their transport function, which is carried out by the phloem and xylem, especially by the sieve elements in the phloem system. The phloem is an important conduit for transporting photosynthate and signal molecules like metabolites, proteins, small RNAs, and full-length mRNAs. Phloem sap has been used as an unadulterated source to profile phloem proteins and RNAs, but unfortunately, pure phloem sap cannot be obtained in most plant species. Here we make use of laser capture microdissection (LCM) and RNA-seq for an in-depth transcriptional profile of phloem-associated cells of both petioles and stems of potato. To expedite our analysis, we have taken advantage of the potato genome that has recently been fully sequenced and annotated. Out of the 27 k transcripts assembled that we identified, approximately 15 k were present in phloem-associated cells of petiole and stem with greater than ten reads. Among these genes, roughly 10 k are affected by photoperiod. Several RNAs from this day length-regulated group are also abundant in phloem cells of petioles and encode for proteins involved in signaling or transcriptional control. Approximately 22 % of the transcripts in phloem cells contained at least one binding motif for Pumilio, Nova, or polypyrimidine tract-binding proteins in their downstream sequences. Highlighting the predominance of binding processes identified in the gene ontology analysis of active genes from phloem cells, 78 % of the 464 RNA-binding proteins present in the potato genome were detected in our phloem transcriptome. As a reasonable alternative when phloem sap collection is not possible, LCM can be used to isolate RNA from specific cell types, and along with RNA-seq, provides practical access to expression profiles of

  2. A geochemical and sedimentary record of high southern latitude Holocene climate evolution from Lago Fagnano, Tierra del Fuego

    NASA Astrophysics Data System (ADS)

    Moy, Christopher M.; Dunbar, Robert B.; Guilderson, Thomas P.; Waldmann, Nicolas; Mucciarone, David A.; Recasens, Cristina; Ariztegui, Daniel; Austin, James A.; Anselmetti, Flavio S.

    2011-02-01

    Situated at the southern margin of the hemispheric westerly wind belt and immediately north of the Antarctic Polar Frontal zone, Tierra del Fuego is well-positioned to monitor coupled changes in the ocean-atmosphere system of the high southern latitudes. Here we describe a Holocene paleoclimate record from sediment cores obtained from Lago Fagnano, a large lake in southern Tierra del Fuego at 55°S, to investigate past changes in climate related to these two important features of the global climate system. We use an AMS radiocarbon chronology for the last 8000 yr based on pollen concentrates, thereby avoiding contamination from bedrock-derived lignite. Our chronology is consistent with a tephrochronologic age date for deposits from the middle Holocene Volcán Hudson eruption. Combining bulk organic isotopic (δ13C and δ15N) and elemental (C and N) parameters with physical sediment properties allows us to better understand sediment provenance and transport mechanisms and to interpret Holocene climate and tectonic change during the last 8000 yr. Co-variability and long-term trends in C/N ratio, carbon accumulation rate, and magnetic susceptibility reflect an overall Holocene increase in the delivery of terrestrial organic and lithogenic material to the deep eastern basin. We attribute this variability to westerly wind-derived precipitation. Increased wind strength and precipitation in the late Holocene drives the Nothofagus forest eastward and enhances run-off and terrigenous inputs to the lake. Superimposed on the long-term trend are a series of abrupt 9 negative departures in C/N ratio, which constrain the presence of seismically-driven mass flow events in the record. We identify an increase in bulk δ13C between 7000 and 5000 cal yr BP that we attribute to enhanced aquatic productivity driven by warmer summer temperatures. The Lago Fagnano δ13C record shows similarities with Holocene records of sea surface temperature from the mid-latitude Chilean continental

  3. A Geochemical and Sedimentary Record of High Southern Latitude Holocene Climate Evolution from Lago Fagnano, Tierra del Fuego

    SciTech Connect

    Moy, C M; Dunbar, R B; Guilderson, T P; Waldmann, N; Mucciarone, D A; Recasens, C; Austin, J A; Anselmetti, F S

    2010-11-19

    Situated at the southern margin of the hemispheric westerly wind belt and immediately north of the Antarctic Polar Frontal zone, Tierra del Fuego is well-positioned to monitor coupled changes in the ocean-atmosphere system of the high southern latitudes. Here we describe a Holocene paleoclimate record from sediment cores obtained from Lago Fagnano, a large lake in southern Tierra del Fuego at 55{sup o}S, to investigate past changes in climate related to these two important features of the global climate system. We use an AMS radiocarbon chronology for the last 8,000 years based on pollen concentrates, thereby avoiding contamination from bedrock-derived lignite. Our chronology is consistent with a tephrochronologic age date for deposits from the middle Holocene Volcan Hudson eruption. Combining bulk organic isotopic ({delta}{sup 13}C and {delta}{sup 15}N) and elemental (C and N) parameters with physical sediment properties allow us to better understand sediment provenance and transport mechanisms and to interpret Holocene climate and tectonic change during the last 8,000 years. Co-variability and long-term trends in C/N ratio, carbon accumulation rate, and magnetic susceptibility reflect an overall Holocene increase in the delivery of terrestrial organic and lithogenic material to the deep eastern basin. We attribute this variability to westerly wind-derived precipitation. Increased wind strength and precipitation in the late Holocene drives the Nothofagus forest eastward and enhances run-off and terrigenous inputs to the lake. Superimposed on the long-term trend are a series of abrupt 9 negative departures in C/N ratio, which constrain the presence of seismically-driven mass flow events in the record. We identify an increase in bulk {delta}{sup 13}C between 7,000 and 5,000 cal yr BP that we attribute to enhanced aquatic productivity driven by warmer summer temperatures. The Lago Fagnano {delta}{sup 13}C record shows similarities with Holocene records of sea surface

  4. Multiproxy approach revealing climate and cultural changes during the last 26kyrs in south-central Chile

    NASA Astrophysics Data System (ADS)

    Abarzua, Ana M.; Jarpa, Leonora; Martel, Alejandra; Vega, Rodrigo; Pino, Mario

    2010-05-01

    Multiproxy approach from Purén Lumaco Valley (38°S) describes the paleonvironmental history during the Last Maximum Glacial (LGM) in south-central Chile. Three sediment cores and severals AMS 14C dates were used to perform a complete pollen, diatoms, chironomids, and sedimentological records demonstrating the existence of a large and non profundal paleolake, between 25 and 20kyr BP. Some of these evidence are laminated silty-clay sediments (lacustrine rhythmites), associated with the presence of siderite mineral (FeCO3), besides biological proxies like Fragilaria construens and Stauroforma inermes (planctonic diatoms), and Dicrotendipes sp. and Tanytarsini tribe (littoral chironomids). The pollen ensemble reveals the first glacial refuge of Araucaria araucana forests in the low lands during the LGM. The lake was drained abruptly into a swamp/bog at 12kyr BP and colonized by Myrtaceae wet forest. This evidence suggest the dry/warm climate period of early Holocene in south-central Chile. Later, the sediments indicate variable lacustrine levels, and increase of charcoal particles, associated to current climatic conditions. The pollen spectrum dominated by Myrtaceae and Nothofagus contrasts with a strongly disturb current landscape. Actually, Purén-Lumaco valley constitutes a complex peat-bog system dominated by exotic grasses and forest species (Tritricum aestivum, Pinus radiata and Eucalyptus spp.). Some archaeological antecedents in the area document the human development at ca. 7yrs BP. The greatest archaeological characteristic present in the valley is the kuel, a Mapuche earth accumulation. The presence and extension of almost 300 kuel in the valley reflect the social/economic development, and partly explains why the region was the major resistance area for Spanish colonizer during XVI-XVII centuries. Also the archaeological findings reveal the presence of maize pollen (Zea mays) within their food consumption. The influence of climate and human impact in

  5. Climatically driven variations in glacier extent as documented by the laminated proglacial sediment record from Lago del Desierto (Southern Patagonia, Argentina)

    NASA Astrophysics Data System (ADS)

    Enters, D.; Kastner, S.; Ohlendorf, C.; Haberzettl, T.; Kuhn, G.; Lücke, A.; Mayr, C.; Reyss, J.; Wastegard, S.

    2009-12-01

    conditions during the MCA with enhanced runoff due to shrinking glaciers. In contrast, the LIA-like cooling trend coincides with diminished minerogenic supply due to changing glacial activity. For the last century the sediment record documents a decline in precipitation and erosion coherent to the 20th century warming trend. Thus, the proglacial lacustrine sediment record of Lago del Desierto constitutes an link between glacier studies of the South Patagonian Ice Field and tree ring studies from the surrounding Nothofagus forest.

  6. Establishment success of sooty beech scale insects, Ultracoelostoma sp., on different host tree species in New Zealand

    PubMed Central

    Wardhaugh, Carl W.; Didham, Raphael K.

    2006-01-01

    The sooty beech scale insect (Ultracoelostoma sp.) (Hemiptera: Margarodidae) exhibits a highly patchy distribution at local and regional scales. A major factor driving this common distributional phenomenon in other phloem-feeding insects is aggregation and local adaptation. The aim of this study was to determine if Ultracoelostoma was locally adapted to its natal host trees, by contrasting the establishment rates of first instar “crawlers” in reciprocal transfers to natal versus novel hosts. Although there are two closely-related species of sooty beech scale insect, the morphological characters of crawlers in this study were intermediate between those of U. assimile and U. brittini. However, all of the voucher specimens examined had consistent morphology, indicating that they belong to one species which we refer to as Ultracoelostoma sp. Reciprocal transfers of crawlers were carried out between individual red beech (Nothofagus fusca), as well as between mountain beech (N. solandri) and red beech trees, to ascertain if insects had become locally adapted to their individual host tree or to host species. In total, 480 crawlers were placed in enclosures on their natal and novel host trees, of which only 32 (6.7 %) became established. No evidence for local adaptation, either to individual host trees or to host tree species, was found. There was also no difference in crawler establishment between natal and novel hosts. However, crawlers originating from mountain beech trees had significantly higher establishment rates on both natal mountain beech and novel red beech hosts, than did crawlers originating from red beech trees. The superior ability of mountain beech crawlers to become established, even on novel red beech trees, suggests that scale insects on mountain beech trees have higher individual fitness (possibly due to maternal effects mediated by differences in host nutritional quality, defensive compounds or growth rate). This increased fitness may result in

  7. Phylogenetic diversity of true morels (Morchella), the main edible non-timber product from native Patagonian forests of Argentina.

    PubMed

    Pildain, María B; Visnovsky, Sandra B; Barroetaveña, Carolina

    2014-01-01

    Morchella species are edible fungi in high demand and therefore command high prices in world markets. Phenotypic-based identification at the species-level remains inadequate because of their complex life cycles, minor differences and plasticity of morphological characteristics between species, and the lack of agreement between scientific and common names. In Patagonia-Argentina, morels are associated with native forests of Austrocedrus chilensis (Cordilleran or Chilean cypress) and Nothofagus antarctica (ñire) and several exotic conifers that were introduced from western North America. Little is known about their taxonomy and phylogenetic relationships with other species in the genus. This work focused on the identification of collections of Morchella from Patagonia and their phylogenetic relationships with other species from the Northern Hemisphere. The comparison was made by analysis of DNA sequences obtained from four loci: the nuclear ribosomal internal transcribed spacer region (ITS) and the partial RNA polymerase I gene (RPB1) for the complete collection; and ITS, RPB1, RNA polymerase II gene (RPB2), and translation elongation factor (EF1-α) for the species-rich Elata Subclade. Analyses of individual and combined data sets revealed that Patagonian morels belong to the Elata Clade and comprised three strongly supported species-level lineages from both Patagonian native forest, and exotic trees introduced from western North America. One lineage was identified as Morchella frustrata phylogenetic species Mel-2, which is known from the USA and Canada. The second lineage, which appeared to be 'fire-adapted', was identified as Morchella septimelata phylogenetic species (Mel-7), which is also known from the USA. This species was collected from burned native forests mainly composed of A. chilensis and N. antarctica but also Pseudotsuga menziesii (Mirb.) Blanco, which is native to western North America. The phylogenetic analyses suggested that the third species from

  8. Register of the last 1000 years of environmental, climatic and anthropogenic change in Isla Grande de Chiloé, inferred through a multi-proxy approach: Lake Pastahué, Chile-South Center (42°S)

    NASA Astrophysics Data System (ADS)

    Troncoso, Jose; Alvarez, Denisse; Díaz, Gustavo; Fierro, Pablo; Araneda, Alberto; Torrejón, Fernando; Rondanelli, Mauricio; Fagel, Nathalie; Urrutia, Roberto

    2017-04-01

    Knowledge of the past environmental and climatic conditions of the lake ecosystems of the Isla Grande de Chiloé and its relationship with the anthropic effect, on a high temporal resolution scale, is scarcely known. Specifically, multi-proxy studies provide a better understanding of the context in which changes occurred in the past. This insular region is particularly interesting because environmental conditions (pre and post-Hispanic) and knowledge about the impacts generated in the ecosystems during the Spanish colonization process have so far been little studied, compared to the rest of Chile continental. This research is a new contribution to the scarce information existing for the last millennium of the Isla Grande de Chiloé. The objective of this work was to reconstruct the environmental and climatic history of the last 1000 years, from the Lake Pastahué, in the Isla Grande de Chiloé through a multi-proxy analysis and compare them with other records for the region. The core sediment was sub-sampled to perform sedimentological analysis (organic matter, carbonates, magnetic susceptibility and granulometry) and biological indicators (pollen, chironomids). The age model was constructed from the activity of 210Pb,137Cs and 14C. The pollen results reveal a composition of nordpatagónico forest represented by Nothofagus, Weinmannia, Drimys, Tepualia, Myrtaceae, Poaceae and Pteridophyta, while the anthropic effect for the last cm of the profile is represented by Rumex and Pinus. The results show a significant increase in magnetic susceptibility since the middle of the 20th century, suggesting an increase in allochthonous material to the lake. The sedimentological parameters and the chironomid assembly show similar variations along the profile, which also shows changes in the trophic state of the lake. The changes recorded in lake Pastahue are directly related to past climatic phenomena occurring in the last millennium, such as the medieval climatic anomaly (MCA

  9. Oligocene to Miocene terrestrial climate change and the demise of forests on Wilkes Land, East Antarctica

    NASA Astrophysics Data System (ADS)

    Salzmann, Ulrich; Strother, Stephanie; Sangiorgi, Francesca; Bijl, Peter; Pross, Joerg; Woodward, John; Escutia, Carlota; Brinkhuis, Henk

    2016-04-01

    The question whether Cenozoic climate was warm enough to support a substantial vegetation cover on the Antarctic continent is of great significance to the ongoing controversial debate on the dynamic behaviour of Antarctic land ice during the transition from a greenhouse to an icehouse world. Here we present palynological results from an Oligocene to Miocene sediment record provided by the Integrated Ocean Drilling Program Expedition 318 to the Wilkes Land margin (East Antarctica). The Oligocene assemblages (33.9-23 Ma) are dominated by pollen and spores from temperate forest and sub-Antarctic shrub vegetation inhabiting different altitudinal zones. These include a lowland cold temperate forest with Dacrydium and Lagarostrobos (both common in southern forests of New Zealand and Tasmania today) and a high altitude tundra shrubland comprising Microcachrys, Nothofagus (southern beech) and Podocarpaceae conifers. A decline in pollen percentages of Dacrydium and Lagarostrobos and absence of Proteaceae indicate climate cooling during the late Oligocene (~25-23 Ma). However, the continuous presence of Lagarostrobos suggests that the full transition to a tundra environment had not yet occurred and climate on Wilkes Land during the late Oligocene was still warm enough to support forest vegetation in sheltered areas. Temperature reconstructions derived from the fossil pollen assemblages using the Coexistence Approach suggest mean annual temperatures (MATs) between 6.7-13.7°C during the early Oligocene and a drop of minimum MATs to 5.8°C in the late Oligocene. Pollen of "unambiguous" forest indicators, such as Lagarostrobos, are absent in the Miocene sediment record (16.2 -12.5 Ma) but temperatures were still high enough (minimum MATs > 5°C) to sustain a woody sub-Antarctic vegetation under partially ice-free conditions. Wilkes Land provides a unique record of Antarctic vegetation change from a subtropical, highly diverse Eocene rainforest to an Oligocene cold temperate

  10. Long-term vegetation, climate and ocean dynamics inferred from a 73,500 years old marine sediment core (GeoB2107-3) off southern Brazil

    NASA Astrophysics Data System (ADS)

    Gu, Fang; Zonneveld, Karin A. F.; Chiessi, Cristiano M.; Arz, Helge W.; Pätzold, Jürgen; Behling, Hermann

    2017-09-01

    Long-term changes in vegetation and climate of southern Brazil, as well as ocean dynamics of the adjacent South Atlantic, were studied by analyses of pollen, spores and organic-walled dinoflagellate cysts (dinocysts) in marine sediment core GeoB2107-3 collected offshore southern Brazil covering the last 73.5 cal kyr BP. The pollen record indicates that grasslands were much more frequent in the landscapes of southern Brazil during the last glacial period if compared to the late Holocene, reflecting relatively colder and/or less humid climatic conditions. Patches of forest occurred in the lowlands and probably also on the exposed continental shelf that was mainly covered by salt marshes. Interestingly, drought-susceptible Araucaria trees were frequent in the highlands (with a similar abundance as during the late Holocene) until 65 cal kyr BP, but were rare during the following glacial period. Atlantic rainforest was present in the northern lowlands of southern Brazil during the recorded last glacial period, but was strongly reduced from 38.5 until 13.0 cal kyr BP. The reduction was probably controlled by colder and/or less humid climatic conditions. Atlantic rainforest expanded to the south since the Lateglacial period, while Araucaria forests advanced in the highlands only during the late Holocene. Dinocysts data indicate that the Brazil Current (BC) with its warm, salty and nutrient-poor waters influenced the study area throughout the investigated period. However, variations in the proportion of dinocyst taxa indicating an eutrophic environment reflect the input of nutrients transported mainly by the Brazilian Coastal Current (BCC) and partly discharged by the Rio Itajaí (the major river closest to the core site). This was strongly related to changes in sea level. A stronger influence of the BCC with nutrient rich waters occurred during Marine Isotope Stage (MIS) 4 and in particular during the late MIS 3 and MIS 2 under low sea level. Evidence of Nothofagus pollen

  11. Emission factors of particulate matter, polycyclic aromatic hydrocarbons, and levoglucosan from wood combustion in south-central Chile.

    PubMed

    Jimenez, Jorge; Farias, Oscar; Quiroz, Roberto; Yañez, Jorge

    2017-07-01

    In south-central Chile, wood stoves have been identified as an important source of air pollution in populated areas. Eucalyptus (Eucalyptus globulus), Chilean oak (Nothofagus oblique), and mimosa (Acacia dealbata) were burned in a single-chamber slow-combustion wood stove at a controlled testing facility located at the University of Concepción, Chile. In each experiment, 2.7-3.1 kg of firewood were combusted while continuously monitoring temperature, exhaust gases, burn rate, and collecting particulate matter samples in Teflon filters under isokinetic conditions for polycyclic aromatic hydrocarbon and levoglucosan analyses. Mean particulate matter emission factors were 2.03, 4.06, and 3.84 g/kg dry wood for eucalyptus, oak, and mimosa, respectively. The emission factors were inversely correlated with combustion efficiency. The mean emission factors of the sums of 12 polycyclic aromatic hydrocarbons in particle phases were 1472.5, 2134.0, and 747.5 μg/kg for eucalyptus, oak, and mimosa, respectively. Fluoranthene, pyrene, benzo[a]anthracene, and chrysene were present in the particle phase in higher proportions compared with other polycyclic aromatic hydrocarbons that were analyzed. Mean levoglucosan emission factors were 854.9, 202.3, and 328.0 mg/kg for eucalyptus, oak, and mimosa, respectively. Since the emissions of particulate matter and other pollutants were inversely correlated with combustion efficiency, implementing more efficient technologies would help to reduce air pollutant emissions from wood combustion. Residential wood burning has been identified as a significant source of air pollution in populated areas. Local wood species are combusted for home cooking and heating, which releases several toxic air pollutants, including particulate matter, carbon monoxide, and polycyclic aromatic hydrocarbons. Air pollutant emissions depend on the type of wood and the technology and operational conditions of the wood stove. A better understanding of emissions from

  12. Towards a common methodology for developing logistic tree mortality models based on ring-width data.

    PubMed

    Cailleret, Maxime; Bigler, Christof; Bugmann, Harald; Camarero, Jesús Julio; Cˇufar, Katarina; Davi, Hendrik; Mészáros, Ilona; Minunno, Francesco; Peltoniemi, Mikko; Robert, Elisabeth M R; Suarez, María Laura; Tognetti, Roberto; Martínez-Vilalta, Jordi

    2016-09-01

    Tree mortality is a key process shaping forest dynamics. Thus, there is a growing need for indicators of the likelihood of tree death. During the last decades, an increasing number of tree-ring based studies have aimed to derive growth-mortality functions, mostly using logistic models. The results of these studies, however, are difficult to compare and synthesize due to the diversity of approaches used for the sampling strategy (number and characteristics of alive and death observations), the type of explanatory growth variables included (level, trend, etc.), and the length of the time window (number of years preceding the alive/death observation) that maximized the discrimination ability of each growth variable. We assess the implications of key methodological decisions when developing tree-ring based growth-mortality relationships using logistic mixed-effects regression models. As examples, we use published tree-ring datasets from Abies alba (13 different sites), Nothofagus dombeyi (one site), and Quercus petraea (one site). Our approach is based on a constant sampling size and aims at (1) assessing the dependency of growth-mortality relationships on the statistical sampling scheme used, (2) determining the type of explanatory growth variables that should be considered, and (3) identifying the best length of the time window used to calculate them. The performance of tree-ring-based mortality models was reasonably high for all three species (area under the receiving operator characteristics curve, AUC > 0.7). Growth level variables were the most important predictors of mortality probability for two species (A. alba, N. dombeyi), while growth-trend variables need to be considered for Q. petraea. In addition, the length of the time window used to calculate each growth variable was highly uncertain and depended on the sampling scheme, as some growth-mortality relationships varied with tree age. The present study accounts for the main sampling-related biases to

  13. Southern high-latitude terrestrial climate change during the Palaeocene-Eocene derived from a marine pollen record (ODP Site 1172, East Tasman Plateau)

    NASA Astrophysics Data System (ADS)

    Contreras, L.; Pross, J.; Bijl, P. K.; O'Hara, R. B.; Raine, J. I.; Sluijs, A.; Brinkhuis, H.

    2014-07-01

    Reconstructing the early Palaeogene climate dynamics of terrestrial settings in the high southern latitudes is important to assess the role of high-latitude physical and biogeochemical processes in the global climate system. However, whereas a number of high-quality Palaeogene climate records has become available for the marine realm of the high southern latitudes over the recent past, the long-term evolution of coeval terrestrial climates and ecosystems is yet poorly known. We here explore the climate and vegetation dynamics on Tasmania from the middle Palaeocene to the early Eocene (60.7-54.2 Ma) based on a sporomorph record from Ocean Drilling Program (ODP) Site 1172 on the East Tasman Plateau. Our results show that three distinctly different vegetation types thrived on Tasmania under a high-precipitation regime during the middle Palaeocene to early Eocene, with each type representing different temperature conditions: (i) warm-temperate forests dominated by gymnosperms that were dominant during the middle and late Palaeocene (excluding the middle/late Palaeocene transition); (ii) cool-temperate forests dominated by southern beech (Nothofagus) and araucarians that transiently prevailed across the middle/late Palaeocene transition interval (~ 59.5 to ~ 59.0 Ma); and (iii) paratropical forests rich in ferns that were established during and in the wake of the Palaeocene-Eocene Thermal Maximum (PETM). The transient establishment of cool-temperate forests lacking any frost-sensitive elements (i.e. palms and cycads) across the middle/late Palaeocene transition interval indicates markedly cooler conditions, with the occurrence of frosts in winter, on Tasmania during that time. The integration of our sporomorph data with previously published TEX86-based sea-surface temperatures from ODP Site 1172 documents that the vegetation dynamics on Tasmania were closely linked with the temperature evolution in the Tasman sector of the Southwest Pacific region. Moreover, the

  14. Southern high-latitude terrestrial climate change during the Paleocene-Eocene derived from a marine pollen record (ODP Site 1172, East Tasman Plateau)

    NASA Astrophysics Data System (ADS)

    Contreras, L.; Pross, J.; Bijl, P. K.; O'Hara, R. B.; Raine, J. I.; Sluijs, A.; Brinkhuis, H.

    2014-01-01

    Reconstructing the early Paleogene climate dynamics of terrestrial settings in the high southern latitudes is important to assess the role of high-latitude physical and biogeochemical processes in the global climate system. However, whereas a number of high-quality Paleogene climate records has become available for the marine realm of the high southern latitudes over the recent past, the long-term evolution of coeval terrestrial climates and ecosystems is yet poorly known. We here explore the climate and vegetation dynamics on Tasmania from the middle Paleocene to the early Eocene (60.7-54.2 Ma) based on a sporomorph record from Ocean Drilling Program (ODP) Site 1172 on the East Tasman Plateau. Our results show that three distinctly different vegetation types thrived on Tasmania under a high-precipitation regime during the middle Paleocene to early Eocene, with each type representing different temperature conditions: (i) warm-temperate forests dominated by gymnosperms that were dominant during the middle and late Paleocene; (ii) cool-temperate forests dominated by southern beech (Nothofagus) and araucarians across the middle/late Paleocene transition interval (~59.5 to ~59.0 Ma); and (iii) paratropical forests rich in ferns that were established during and in the wake of the Paleocene-Eocene Thermal Maximum (PETM). The transient establishment of cool-temperate forests lacking any frost-sensitive elements (i.e., palms and cycads) across the middle/late Paleocene transition interval indicates markedly cooler conditions, with the occurrence of frosts in winter, on Tasmania during that time. The integration of our sporomorph data with previously published TEX86-based sea-surface temperatures from ODP Site 1172 documents that the vegetation dynamics on Tasmania were closely linked with the temperature evolution in the Tasman sector of the Southwest Pacific region. Moreover, the comparison of our season-specific climate estimates for the sporomorph assemblages from ODP

  15. A review of Tertiary climate changes in southern South America and the Antarctic Peninsula. Part 2: continental conditions

    NASA Astrophysics Data System (ADS)

    Le Roux, J. P.

    2012-03-01

    uninterruptedly into the Pleistocene. The Antarctic Peninsula saw its first mountain glaciation between 45 and 41 Ma, with major ice sheet expansion commencing at about 34 Ma. Isolated stands of Nothofagus forests were still present in low-lying areas, suggesting that the glaciers were initially wet-based, but dry-based glaciers were established at around 8 Ma. Although temperatures rose briefly during the Messinian-Pliocene transition, causing sub-Antarctic flora to retreat to higher elevations of the Transantarctic Mountains, the present cold polar conditions were finally established by about 3 Ma.

  16. Is New Zealand vegetation really 'problematic'? Dansereau's puzzles revisited.

    PubMed

    Wilson, J Bastow; Lee, William G

    2012-05-01

    Over four decades ago, Pierre Dansereau, the noted North American ecologist, proposed six features of New Zealand vegetation as being problematic or unusual in a global context. We examine his propositions in the light of current ecological knowledge to determine whether or not these can still be considered unusual characteristics of New Zealand vegetation. (1) 'Climatic change is still progressing' resulting in disequilibrium between species' distributions and the present climate. New data and methods of analysis now available have removed the impression that Dansereau gained of imprecise zonation, unclear vegetation/climate relations and missing vegetation types. Communities cited as having regeneration failure can now be seen as even-aged stands that developed after major disturbance, although there are other, also non-climatic, explanations. However, the cause of the Westland 'Nothofagus gap' has become more, rather than less, controversial. (2) 'Continuity of community composition defies classification' and 'Very few New Zealand associations have faithful species' are correct observations, but perhaps equally true of vegetation elsewhere. Dansereau's assertion of low species richness in New Zealand is not supported by the comparative data available. (3) 'Lack of intolerant [i.e. mid-seral] trees …' is not evident with newer information. The order of species in succession, seen as unclear by Dansereau, has been determined by a range of approaches, largely confirming each other. (4) 'Discrepancies of form and function …' in divaricate shrubs and widespread heteroblasty are still controversial, with many more explanations. Several abiotic explanations have failed to stand up to investigation. Explanations in terms of herbivory have been well supported, although the extinction of the large avian herbivores makes certainty impossible. (5) 'Incidence of hybridization …' remains problematic. We do not know whether the incidence is unusually high, as Dansereau

  17. Aggregate and soil organic carbon dynamics in South Chilean Andisols

    NASA Astrophysics Data System (ADS)

    Huygens, D.; Boeckx, P.; Van Cleemput, O.; Oyarzún, C.; Godoy, R.

    2005-06-01

    Extreme sensitivity of soil organic carbon (SOC) to climate and land use change warrants further research in different terrestrial ecosystems. The aim of this study was to investigate the link between aggregate and SOC dynamics in a chronosequence of three different land uses of a south Chilean Andisol: a second growth Nothofagus obliqua forest (SGFOR), a grassland (GRASS) and a Pinus radiata plantation (PINUS). Total carbon content of the 0-10cm soil layer was higher for GRASS (6.7 kg C m-2) than for PINUS (4.3 kg C m-2, while TC content of SGFOR (5.8 kg C m-2) was not significantly different from either one. High extractable oxalate and pyrophosphate Al concentrations (varying from 20.3-24.4 g kg-1, and 3.9-11.1 g kg-1, respectively) were found in all sites. In this study, SOC and aggregate dynamics were studied using size and density fractionation experiments of the SOC, δ13C and total carbon analysis of the different SOC fractions, and C mineralization experiments. The results showed that electrostatic sorption between and among amorphous Al components and clay minerals is mainly responsible for the formation of metal-humus-clay complexes and the stabilization of soil aggregates. The process of ligand exchange between SOC and Al would be of minor importance resulting in the absence of aggregate hierarchy in this soil type. Whole soil C mineralization rate constants were highest for SGFOR and PINUS, followed by GRASS (respectively 0.495, 0.266 and 0.196 g CO2-Cm-2d-1 for the top soil layer). In contrast, incubation experiments of isolated macro organic matter fractions gave opposite results, showing that the recalcitrance of the SOC decreased in another order: PINUS>SGFOR>GRASS. We deduced that electrostatic sorption processes and physical protection of SOC in soil aggregates were the main processes determining SOC stabilization. As a result, high aggregate carbon concentrations, varying from 148 till 48 g kg-1, were encountered for all land use sites. Al

  18. Recent Deglaciation of Darwin Mountains (Tierra de Fuego) after Little Ice Age: monitoring by photogrammetry, lichenometry, dendrochronology and field studies.

    NASA Astrophysics Data System (ADS)

    García-Sancho, L.; Palacios, D.; Zamorano, J. J.; Green, A.; Vivas, M.; Pintado, A.

    2012-04-01

    Glaciers from the Darwin mountain range have been retreating since the Little Ice Age (LIA). However, the amount of retreat varies and is minimal for some glacial snouts and substantial for others. Possible explanations for this different behaviour include climatic and glacial dynamic causes. The aim of this work was to analyse the impact of climate change on these glaciers. The research site was the terminus of glacier Pia, which descends to the south of Mount Darwin (2488 m asl, 54°45'S, 69°29'W) and reaches the coastline at the Beagle Channel. The terminus is situated some hundreds of meters above the LIA moraine but, whereas one sector retreated rapidly and then stabilized, another sector has had several advances and retreats leaving a number of moraine arches. To better understand the origin of this dynamic behaviour, we undertook a study of the evolution of the terminus of glacier Pia over the last 60 years. We used aerial photographs and satellite images to determine the exact location of the glacial terminus in certain years (1943, 1963, 1987, 1990, 2001 and 2006). These results were completed in 2008 and 2009 through field work. We also carried out lichenometric studies of the two most abundant lichen species that rapidly colonize the moraine boulders abandoned by the glacier: Placopsis perrugosa and Rhizocarpon geographicum. By comparing results from field work carried out in 2008 and 2009, we were able to determine the growth rate of these two species (García-Sancho et al. 2011). In addition, we also carried out a dendrochronological study of Nothofagus antarctica and N. betuloides. The use of the four techniques involved in this study (photogrammetry, lichenometry, dendrochronology and multiyear field work) allowed us to establish the ecesis period of each species as well as their growth curves, from which we can deduce the movements of the glacial terminus from the end of the LIA to the present. From this study we can infer that the different

  19. Lichen Persistence and Recovery in Response to Varied Volcanic Disturbances

    NASA Astrophysics Data System (ADS)

    Nelson, P.; Wheeler, T. B.

    2015-12-01

    Volcanic eruptions produce many ecological disturbances that structure vegetation. While lichens are sensitive to disturbances, little is known about their responses to volcanic disturbances, except for colonization of lava. We examined lichen community responses through time to different disturbances produced by the May 1, 2008 eruption of Volcan Chaiten in south-central Chile. Pre-eruption vegetation near the volcano was old-growth Valdivian temperate rainforest dominated by closed-canopy Nothofagus sp... In 2012, we installed thirteen 1-acre plots across volcanic disturbance zones on which a time-constrained search was done for all macrolichen species, each of which was assigned an approximate log10 categorical abundance. We also installed a 0.2 m2 quadrat on two representative trees per plot for repeat photography of lichen cover. We remeasured at least one plot per disturbance zone in 2014 and re-photographed tree quadrats in 2013 and 2014. We then analyzed species composition and abundance differences among disturbance zones. In 2012, the blast (pyroclastic density flow), scorch (standing scorched forest at the edge of the blast) and deep tephra (>10 cm) zones had the lowest lichen species richness (5-13 species), followed by reference (unimpacted) and shallow (<10 cm) tephra (17-20 species). Gravel rain (preexisting rock ejected by eruption initiation), gravel rain + pumice and flooded forests (fluvially reworked volcanic material entrained by heavy rains) were species-rich (25-42 species). In 2014, the blast and deep tephra had regained 2-3 times the number of lichen species since 2012 while the light tephra and reference were essentially unchanged. Gravel rain, gravel rain + pumice and flooded forest plots all had about the same number of species in 2014 as 2012. Lichen colonization and growth in tree quadrats varied widely, from very little colonization in the blast to prolific colonization in the gravel rain + pumice zone. Lichen's varied responses to

  20. The Neogene Environment of the Beardmore Glacier, Transantarctic Mountains

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Cantrill, D. J.; Francis, J. E.; Roof, S. R.

    2004-12-01

    , the absence of solar heating for about 5.5 months, even though there would have been additional heat from open water in the fjord, would have resulted in a low mean annual temperature. Mean summer temperatures, based on the minimal thermal requirements for Nothofagus, listroderine weevils, and freshwater molluscs, are estimated to have been between 4 and 5°C for at least two summer months. The research is supported by NSF grant OPP-0230696

  1. Major Mid-Miocene Climate Change In The Transantarctic Mountains

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A. R.; Marchant, D. R.

    2007-12-01

    Independent lines of evidence from paleoecology, glacial geology and marine isotopes indicate major climate change in the Dry Valley sector of the Transantarctic Mountains (TAM) at c.14 Ma. A fossil assemblage of pollen and spores, freshwater diatoms, ostracods, mosses, and insect remains has been recovered from lacustrine sediments preserved in a small morainic lake basin in the western Olympus Range. The diatom assemblage indicates that the lake existed for >103yr and was ice-free during summers. Based on the moss and insect fossils the minimum mean summer temperature (MST- Dec-Feb) was 2°C but could have been as high as 5°C. Today at the site the MST is c. -15°C. The lake-marginal vegetation was a sparse tundra dominated by mosses and liverworts. Based on pollen, Nothofagus (southern beech) was part of the lowland regional vegetation and individual dwarfed shrubs may have grown on the slopes surrounding the lake basin. The age of the deposits is well-constrained by an 40Ar/39Ar age of 14.11 ± 0.11 Ma from an in situ volcanic ash within related lacustrine sediments. Based on an independent study of the glacial stratigraphy of the western Wright and McKelvey valleys, diamictites of a wet-based glacial regime had been replaced by those of cold-based regime by 13.85 ± 0.03 Ma. The drop in temperatures and the cessation of meltwater at c. 14 Ma would have caused the regional extinction of all plant and insect life with the exception of the hardiest of soil-dwelling organisms. Paleobotanical evidence indicates that Antarctica had likely been vegetated throughout the Cenozoic, with forests replaced by tundra during the early Oligocene. The mid-Miocene extinction marks the end of tundra in the interior of Antarctica and its replacement by the polar desert biota which exists today. Changes in δ18O and Mg/Ca ratios from different sectors of the Southern Ocean indicate sea surface temperature cooling and ice sheet growth between 13.8 - 14.2 Ma. The close correlation

  2. Characterization of Palo Podrido, a Natural Process of Delignification in Wood †

    PubMed Central

    Agosin, Eduardo; Blanchette, Robert A.; Silva, Herman; Lapierre, Catherine; Cease, Kory R.; Ibach, Rebecca E.; Abad, André R.; Muga, Pedro

    1990-01-01

    Chemical and morphological changes of incipient to advanced stages of palo podrido, an extensively delignified wood, and other types of white rot decay found in the temperate forests of southern Chile were investigated. Palo podrido is a general term for white rot decay that is either selective or nonselective for the removal of lignin, whereas palo blanco describes the white decayed wood that has advanced stages of delignification. Selective delignification occurs mainly in trunks of Eucryphia cordifolia and Nothofagus dombeyi, which have the lowest lignin content and whose lignins have the largest amount of β-aryl ether bonds and the highest syringyl/guaiacyl ratio of all the native woods included in this study. A Ganoderma species was the main white rot fungus associated with the decay. The structural changes in lignin during the white rot degradation were examined by thioacidolysis, which revealed that the β-aryl ether-linked syringyl units were more specifically degraded than the guaiacyl ones, particularly in the case of selective delignification. Ultrastructural studies showed that the delignification process was diffuse throughout the cell wall. Lignin was first removed from the secondary wall nearest the lumen and then throughout the secondary wall toward the middle lamella. The middle lamella and cell corners were the last areas to be degraded. Black manganese deposits were found in some, but not all, selectively delignified samples. In advanced stages of delignification, almost pure cellulose could be found, although with a reduced degree of polymerization. Cellulolytic enzymes appeared to be responsible for depolymerization. A high brightness and an easy refining capacity were found in an unbleached pulp made from selectively delignified N. dombeyi wood. Its low viscosity, however, resulted in poor resistance properties of the pulp. The last stage of degradation (i.e., decomposition of cellulose-rich secondary wall layers) resulted in a gelatinlike

  3. Late Holocene Lacustrine Records of Climate and Vegetation Change From Southern Patagonia, Chile

    NASA Astrophysics Data System (ADS)

    Moy, C. M.; Francois, J.; Moreno, P.; Villa Martinez, R.; Dunbar, R. B.

    2004-12-01

    The westerly wind field is one of the most prominent atmospheric circulation features in the Southern Hemisphere, having a major impact on the climate of Chile and hydrographic conditions in the Southern Ocean. The latitudinal position and strength of the westerlies directly influences the amount and isotopic composition of precipitation that falls in southern Chile. Although instrumental records provide information on how the westerlies have varied over the recent past there is still an incomplete understanding of how the strength and latitudinal position of the southern westerlies have changed during the Holocene and how the wind field has varied at millennial to sub-decadal timescales. In this study we relate changes in the westerly winds to changes in water balance as recorded in closed-basin lakes. Sediment cores were obtained from Laguna Guanacos in Parque Nacional Torres del Paine (51° S, 72° W) during the austral summer of 2004 and sampled at 1-2cm intervals for pollen, charcoal, and stable isotope analysis. Laguna Guanacos is a small closed-basin lake situated in the core of westerly wind belt and is therefore sensitive to fluctuations in the strength and position of the westerlies. The sediment cores obtained from the lake reveal high concentrations of organic mater ( ˜20%) and biogenic carbonate, which is rare in Chilean Patagonia. AMS radiocarbon dates on the organic and carbonate fractions indicate that the record spans the last ˜14,000 calendar years and modern dates from core tops suggest little influence by old or dead carbon sources. Pollen analysis on the late Holocene portion of the record reveals a significant expansion of the Nothofagus forest since ˜3500 cal yr BP, suggesting an overall increase in precipitation during this interval. Millennial- and centennial-scale fluctuations in bulk carbonate content and forest and steppe pollen are superimposed upon this pattern, providing a view of a highly dynamic westerly wind regime and forest

  4. Mapping the Ancient Maya Landscape from Space

    NASA Technical Reports Server (NTRS)

    Sever, Tom

    2003-01-01

    This project uses new satellite and airborne imagery in combination with remote sensing, GIS, and GPS technology to understand the dynamics of how the Maya successfully interacted with their karst topographic landscape for several centuries in the northern Peten region of Guatemala. The ancient Maya attained one of the greatest population densities in human history in the tropical forest of the Peten, Guatemala, and it was in this region that the Maya civilization began, flourished, and abruptly disappeared for unknown reasons around AD 800. How the Maya were able to successfully manage water and feed this dense population is not known at this time. However, a recent NASA-funded project was the first to investigate large seasonal swamps (bajos) that make up 40 percent of the landscape. Through the use of remote sensing, ancient Maya features such as cities, roadways, canals and water reservoirs have been detected and verified through ground reconnaissance. The results of this research cast new light on the adaptation of the ancient Maya to their environment. Micro-environmental variation within the wetlands was elucidated and the different vegetational associations identified in the satellite imagery. More than 70 new archeological sites within and at the edges of the bajo were mapped and tested. Modification of the landscape by the Maya in the form of dams and reservoirs in the Holmul River and its tributaries and possible drainage canals in bajos was demonstrated. The recent acquisition of one-meter IKONOS imagery and high resolution STAR-3i radar imagery (2.5m backscatter/ 10m DEM), opens new possibilities for understanding how a civilization was able to survive for centuries upon a karst topographic landscape and their human-induced effects upon the local climate. This understanding is critical for the current population that is presently experiencing rapid population growth and destroying the landscape through non-traditional farming and grazing techniques

  5. Landscape Archeology: Remote Sensing Investigation of the Ancient Maya in the Peten Rainforest of Northern Guatemala

    NASA Technical Reports Server (NTRS)

    Sever, Thomas L.; Irwin, Daniel E.; Arnold, James E. (Technical Monitor)

    2002-01-01

    Through the use of airborne and satellite imagery we are improving our ability to investigate ancient Maya settlement, subsistence, and landscape modification in this dense forest region. Today the area is threatened by encroaching settlement and deforestation. However, it was in this region that the Maya civilization began, flourished, and abruptly disappeared for unknown reasons in the 9th century AD. At the time of their collapse they had attained one of the highest population densities in human history. How the Maya were able to successfully manage water and feed this dense population is not well understood at this time. A NASA-funded project used remote sensing technology to investigate large seasonal swamps (bajos) that make up 40 percent of the landscape. Through the use of remote sensing, ancient Maya features such as sites, roadways, canals and water reservoirs have been detected and verified through ground reconnaissance. The results of this preliminary research cast new light on the adaptation of the ancient Maya to their environment. Microenvironmental variation within the wetlands was elucidated and the different vegetation associations identified in the satellite imagery. More than 70 new archeological sites within and at the edges of the bajo were mapped and tested. Modification of the landscape by the Maya in the form of dams and reservoirs in the Holmul River and its tributaries and possible drainage canals in bajos was demonstrated. The use of Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM), one-meter IKONOS satellite imagery, as well as high resolution airborne STAR-3i radar imagery--2.5 meter backscatter/10 meter Digital Elevation Model (DEM)--are opening new possibilities for understanding how a civilization was able to survive for centuries upon a karat topographic landscape. This understanding is critical for the current population that is currently experiencing rapid population growth and destroying the landscape through

  6. [A very slow-growing exophytic hemisphere glioma: a case report].

    PubMed

    Velásquez, Carlos; Caballero, Hugo; Bucheli, Carlos; Berciano, José; Vázquez-Barquero, Alfonso; Martino, Juan

    2016-01-01

    Introduccion. Los gliomas de bajo grado presentan un patron de crecimiento caracteristico a traves de las fibras de la sustancia blanca. El crecimiento exofitico en gliomas de bajo grado hemisfericos no se ha descrito previamente. Se presenta un caso de glioma hemisferico de lenta progresion y con crecimiento exofitico. Caso clinico. Varon de 55 años, con crisis parciales motoras secundarias a un oligodendroglioma de grado II de la Organizacion Mundial de la Salud. El tumor infiltraba la circunvolucion frontal superior con extension exofitica que se extendia por encima de la circunvolucion precentral. Fue seguido con controles clinicorradiologicos durante 23 años. El analisis de la evolucion radiologica del tumor demostraba un crecimiento tumoral lento, con una velocidad de crecimiento de 0,5 mm al año. Durante la exeresis quirurgica se definio un plano subaracnoideo entre el componente exofitico y la circunvolucion precentral, que se encontraba desplazada inferiormente sin infiltracion tumoral. La estimulacion electrica intraoperatoria no evidencio funcion en el componente exofitico, pero si en la circunvolucion precentral. No se observaron deficits neurologicos postoperatorios. Conclusiones. La velocidad de crecimiento en gliomas de bajo grado se ha estimado en 4-6 mm al año. El tumor que se describe aqui tiene una velocidad de crecimiento de 0,5 mm al año, muy por debajo de esta media. La identificacion de la porcion exofitica es un paso importante en la planificacion preoperatoria. Este componente es mas facil de resecar debido al plano de clivaje subaracnoideo y a la ausencia de funcion.

  7. Explicación de las disparidades raciales en la salud neonatal en Brasil*

    PubMed Central

    Nyarko, Kwame A.; López-Camelo, Jorge; Castilla, Eduardo E.; Wehby, George L.

    2015-01-01

    Objetivos. Buscamos cuantificar la manera en que los efectos socioeconómicos, demográficos, geográficos y de atención de salud explican las disparidades raciales en las tasas de bajo peso al nacer y prematuridad en Brasil. Métodos. Utilizamos una muestra de 8 949 niños nacidos entre 1995 y el 2009 en 15 ciudades y 7 provincias de Brasil. Nos centramos en las disparidades en la prevalencia de bajo peso al nacer (< 2 500 g) y prematuridad (< 37 semanas de gestación) en recién nacidos de ascendencia solo africana o mezclada con otras ascendencias y de ascendencia solo europea. Usamos un modelo de descomposición para cuantificar la contribución de los factores conceptualmente pertinentes a esas disparidades. Resultados. El modelo permitió explicar entre 45% y 94% de las disparidades en cuanto al bajo peso al nacer y entre 64% y 94% de las disparidades en cuanto a la prematuridad entre los grupos de ascendencia africana y de ascendencia europea. Las diferencias en el uso de atención prenatal y en la ubicación geográfica fueron los factores más importantes, seguidos por las diferencias socioeconómicas. El modelo permitió explicar la mayoría de las disparidades en los recién nacidos de ascendencia africana mezclada y parte de las disparidades en los de ascendencia solo africana. Conclusiones. En las políticas públicas para mejorar la salud infantil se deben abordar las diferencias en cuanto a la atención prenatal y la ubicación geográfica a fin de reducir las disparidades en materia de salud entre los recién nacidos de ascendencia africana y los de ascendencia europea en Brasil.

  8. [Nutritional status of two generations of brothers and sisters <5 years of age beneficiaries from opportunities living in marginalized rural communities in Chiapas, Mexico].

    PubMed

    García-Parra, Esmeralda; Ochoa-Díaz-López, Héctor; García-Miranda, Rosario; Moreno-Altamirano, Laura; Morales, Helda; Estrada-Lugo, Erin Ingrid Jane; Solís-Hernández, Roberto

    2015-06-01

    En México, en las últimas décadas se han desarrollado varios programas para erradicar el problema de la desnutrición en infantes < de 5 años, principalmente de aquellos que viven en áreas indígenas y rurales. No obstante, no existe suficiente evidencia sobre su impacto en la salud y la nutrición infantil. Objetivo: describir los cambios nutricionales de dos generaciones de hermanos(as) que han sido beneficiados por el programa Oportunidades en comunidades rurales de Chiapas. Métodos: estudio transversal. Se determinó: bajo peso, baja talla, emaciación y SP + O (Sobrepeso más Obesidad). Los hermanos(as) mayores fueron evaluados en los años 2002-2003, para el 2010-2011 se evaluaron a los hermanos( as) menores, ambos grupos eran < de 5 años de edad en el momento de conseguir la información. Resultados: la desnutrición en sus tres formas es un problema, 43,4% de los hermanos(as) evaluados(as) en 2010-2011 presentaron baja talla, la prevalencia de bajo peso disminuyó de 18% a 13,2%, la emaciación (peso bajo para la talla) aumentó de 8,1% a 10.4%. El SP + O aumentó significativamente 12 puntos porcentuales entre los hermanos(as) de 24,8% en 2002-2003 a 36,8% en 2010-2011. La desnutrición en los niños (varones) es menor que la de sus hermanos de la generación de 2002- 2003 (baja talla p =.

  9. Landscape Archeology: Remote Sensing Investigation of the Ancient Maya in the Peten Rainforest of Northern Guatemala

    NASA Technical Reports Server (NTRS)

    Sever, Thomas L.; Irwin, Daniel E.; Arnold, James E. (Technical Monitor)

    2002-01-01

    Through the use of airborne and satellite imagery we are improving our ability to investigate ancient Maya settlement, subsistence, and landscape modification in this dense forest region. Today the area is threatened by encroaching settlement and deforestation. However, it was in this region that the Maya civilization began, flourished, and abruptly disappeared for unknown reasons in the 9th century AD. At the time of their collapse they had attained one of the highest population densities in human history. How the Maya were able to successfully manage water and feed this dense population is not well understood at this time. A NASA-funded project used remote sensing technology to investigate large seasonal swamps (bajos) that make up 40 percent of the landscape. Through the use of remote sensing, ancient Maya features such as sites, roadways, canals and water reservoirs have been detected and verified through ground reconnaissance. The results of this preliminary research cast new light on the adaptation of the ancient Maya to their environment. Microenvironmental variation within the wetlands was elucidated and the different vegetation associations identified in the satellite imagery. More than 70 new archeological sites within and at the edges of the bajo were mapped and tested. Modification of the landscape by the Maya in the form of dams and reservoirs in the Holmul River and its tributaries and possible drainage canals in bajos was demonstrated. The use of Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM), one-meter IKONOS satellite imagery, as well as high resolution airborne STAR-3i radar imagery--2.5 meter backscatter/10 meter Digital Elevation Model (DEM)--are opening new possibilities for understanding how a civilization was able to survive for centuries upon a karat topographic landscape. This understanding is critical for the current population that is currently experiencing rapid population growth and destroying the landscape through

  10. [Early discharge of the healthy newborn from the nursery of the Hospital Español de México].

    PubMed

    Santos Burgoa-Larrañaga, Lorena; Iglesias-Leboreiro, José; Bernardez-Zapata, Isabel

    2016-01-01

    Introducción: el riesgo-beneficio del alta temprana en neonatos es controversial. No encontramos estudios concluyentes que analicen las variables del neonato y el impacto en su morbilidad al alta temprana. Asociamos estadísticamente variables con alguna terapia adicional que pudiera poner en riesgo al neonato de alta temprana. Métodos: estudio prolectivo observacional en recién nacidos de término desde el nacimiento hasta el alta (de agosto a diciembre de 2013). Se hizo seguimiento telefónico al mes de vida para conocer su estado de salud. Las variables dependientes fueron las horas intrahospitalarias, las terapias adicionales y la atención intrahospitalaria en el primer mes. Resultados: 701 neonatos a término, 41 con terapia adicional, 23 ingresos a UCIN (22 en < 24 horas). Hubo un RR de 12.9 si el Apgar era < 8.8. Hubo 9 veces más riesgo de terapia adicional si había < 38 semanas de gestación. El peso bajo triplicó el riesgo para ingreso a UCIN. Hubo 143 altas tempranas, 58 % seguimiento telefónico, 0 % de reingresos. Las principales variables que influyen en requerir terapia adicional son el Apgar < 8 a los 5 minutos, tener < 38 semanas de gestación y peso bajo.Conclusión: los elementos para el manejo de pacientes con alta temprana son datos de alarma, seguimiento con pediatra a los tres días de vida, vigilancia estrecha si el APGAR es < 8 a los 5 minutos o < 38 semanas de gestación o si hay peso bajo para la edad gestacional.

  11. Mapping the Ancient Maya Landscape from Space

    NASA Technical Reports Server (NTRS)

    Sever, Tom

    2003-01-01

    This project uses new satellite and airborne imagery in combination with remote sensing, GIS, and GPS technology to understand the dynamics of how the Maya successfully interacted with their karst topographic landscape for several centuries in the northern Peten region of Guatemala. The ancient Maya attained one of the greatest population densities in human history in the tropical forest of the Peten, Guatemala, and it was in this region that the Maya civilization began, flourished, and abruptly disappeared for unknown reasons around AD 800. How the Maya were able to successfully manage water and feed this dense population is not known at this time. However, a recent NASA-funded project was the first to investigate large seasonal swamps (bajos) that make up 40 percent of the landscape. Through the use of remote sensing, ancient Maya features such as cities, roadways, canals and water reservoirs have been detected and verified through ground reconnaissance. The results of this research cast new light on the adaptation of the ancient Maya to their environment. Micro-environmental variation within the wetlands was elucidated and the different vegetational associations identified in the satellite imagery. More than 70 new archeological sites within and at the edges of the bajo were mapped and tested. Modification of the landscape by the Maya in the form of dams and reservoirs in the Holmul River and its tributaries and possible drainage canals in bajos was demonstrated. The recent acquisition of one-meter IKONOS imagery and high resolution STAR-3i radar imagery (2.5m backscatter/ 10m DEM), opens new possibilities for understanding how a civilization was able to survive for centuries upon a karst topographic landscape and their human-induced effects upon the local climate. This understanding is critical for the current population that is presently experiencing rapid population growth and destroying the landscape through non-traditional farming and grazing techniques

  12. Effects of Seasonal Upwelling on Inorganic and Organic Matter Dynamics in the Water Column of Eastern Pacific Coral Reefs

    PubMed Central

    Stuhldreier, Ines; Sánchez-Noguera, Celeste; Rixen, Tim; Cortés, Jorge; Morales, Alvaro; Wild, Christian

    2015-01-01

    The Gulf of Papagayo at the northern Pacific coast of Costa Rica experiences pronounced seasonal changes in water parameters caused by wind-driven coastal upwelling. While remote sensing and open water sampling already described the physical nature of this upwelling, the spatial and temporal effects on key parameters and processes in the water column have not been investigated yet, although being highly relevant for coral reef functioning. The present study investigated a range of water parameters on two coral reefs with different exposure to upwelling (Matapalo and Bajo Rojo) in a weekly to monthly resolution over one year (May 2013 to April 2014). Based on air temperature, wind speed and water temperature, three time clusters were defined: a) May to November 2013 without upwelling, b) December 2013 to April 2014 with moderate upwelling, punctuated by c) extreme upwelling events in February, March and April 2014. During upwelling peaks, water temperatures decreased by 7°C (Matapalo) and 9°C (Bajo Rojo) to minima of 20.1 and 15.3°C respectively, while phosphate, ammonia and nitrate concentrations increased 3 to 15-fold to maxima of 1.3 μmol PO43- L-1, 3.0 μmol NH4+ L-1 and 9.7 μmol NO3- L-1. This increased availability of nutrients triggered several successive phytoplankton blooms as indicated by 3- (Matapalo) and 6-fold (Bajo Rojo) increases in chlorophyll a concentrations. Particulate organic carbon and nitrogen (POC and PON) increased by 40 and 70% respectively from February to April 2014. Dissolved organic carbon (DOC) increased by 70% in December and stayed elevated for at least 4 months, indicating high organic matter release by primary producers. Such strong cascading effects of upwelling on organic matter dynamics on coral reefs have not been reported previously, although likely impacting many reefs in comparable upwelling systems. PMID:26560464

  13. FUENTES Infrarrojas EN 2.2 lim EN la Region Asociada AL GLOBULO ORI-1-2

    NASA Astrophysics Data System (ADS)

    Cruz-Gonzalez, J.; Carrasco, L.; Ramos, M. P.

    1987-05-01

    Se ha mapeado en el cercano infrarrojo a 2.2 micras, una región de 2 x 5 minutos de arco asociada al glóbulo ORI-I-2. Se ha detectado emisión infrarroja de fuentes puntuales y emisión extendida de bajo brillo superficial. Se discute la asociación de fuentes de 2.2 micras con la emisión detectada en IRAS y en moléculas de radio frecuencias.

  14. Conceptos Basicos Sobre el Gas Natural

    SciTech Connect

    2016-08-01

    El gas natural abastece cerca de 150.000 vehiculos en los Estados Unidos y aproximadamente 22 millones de vehiculos en todo el mundo. Los vehiculos de gas natural (NGV, por sus siglas en ingles) son una buena opcion para las flotas de vehiculos de alto kilometraje, tales como autobuses, taxis, vehiculos de recoleccion de basura, los cuales son alimentados centralmente u operan dentro de un area limitada o a lo largo de una ruta con estaciones de servicio de gas natural. Las ventajas del gas natural como combustible alternativo incluyen su disponibilidad interna, la red de distribucion establecida, un costo relativamente bajo, y los beneficios de las emisiones.

  15. Recent Advances in Maya Studies Using Remotely Sensed Data

    NASA Technical Reports Server (NTRS)

    Sever, Tom; Irwin, Daniel; Arnold, James E. (Technical Monitor)

    2001-01-01

    The Peten region of northern Guatemala is one of the last places on earth where major archeological sites remain to be discovered. It was in this region that the Maya civilization began, flourished, and abruptly disappeared. Remote sensing technology is helping to locate and map ancient Maya sites that are threatened today by accelerating deforestation and looting. Thematic Mapper and IKONOS satellite and airborne Star3i radar data, combined with Global Positioning System (GPS) technology, are successfully detecting ancient Maya features such as cities, roadways, canals, and water reservoirs. Satellite imagery is also being used to map the bajos, which are seasonally flooded swamps that cover over 40% of the land surface. The use of baJos for farming has been a source of debate within the professional community for many years. But the recent detection and verification of cultural features within the baJo system by our research team are providing conclusive evidence that the ancient Maya had adapted well to wetland environments from the earliest times and utilized them until the time of the Maya collapse. The combination of water management and baJo farming is an important resource for the future of the current inhabitants who are experiencing rapid population growth. Remote sensing imagery is also demonstrating that in the Preclassic period (600 BC- AD 250), the Maya had already achieved a high organizational level as evidenced by the construction of massive temples and an elaborate inter-connecting roadway system. Although they experienced several setbacks such as droughts and hurricanes, the Maya nevertheless managed the delicate forest ecosystem successfully for several centuries. However, around AD 800, something happened to the Maya to cause their rapid decline and eventual disappearance from the region. The evidence indicates that at this time there was increased climatic dryness, extensive deforestation, overpopulation, and widespread warfare. This raises a

  16. Mapping The Ancient Maya Landscape From Space

    NASA Technical Reports Server (NTRS)

    Sever, Tom; Arnold, James E. (Technical Monitor)

    2002-01-01

    The Peten region of northern Guatemala is one of the last places on earth where major archeological sites remain to be discovered. It was in this region that the Maya civilization began, flourished, and abruptly disappeared. Remote sensing technology is helping to locate and map ancient Maya sites that are threatened today by accelerating deforestation and looting. Thematic Mapper and IKONOS satellite and airborne Star3-I radar data, combined with Global Positioning System (GPS) technology, are successfully detecting ancient Maya features such as cities, roadways, canals, and water reservoirs. Satellite imagery is also being used to map the bajos, which are seasonally flooded swamps that cover over 40% of the land surface. The use of bajos for farming has been a source of debate within the professional community for many years. But the recent detection and verification of cultural features within the bajo system by our research team are providing conclusive evidence that the ancient Maya had adapted well to wetland environments from the earliest times and utilized them until the time of the Maya collapse. The use of the bajos for farming is also an important resource for the future of the current inhabitants who are experiencing rapid population growth. Remote sensing imagery is also demonstrating that in the Preclassic period (600 BC- AD 250), the Maya had already achieved a high organizational level as evidenced by the construction of massive temples and an elaborate inter-connecting roadway system. Although they experienced several setbacks such as droughts and hurricanes, the Maya nevertheless managed the delicate forest ecosystem successfully for several centuries. However, around AD 800, something happened to the Maya to cause their rapid decline and eventual disappearance from the region. The evidence indicates that at this time there was increased climatic dryness, extensive deforestation, overpopulation, and widespread warfare. This raises a question that

  17. PubMed

    Olivares Cortes, Sonia; Araneda Flores, Jacqueline; Morales Illanes, Gladys; Leyton Dinamarca, Bárbara; Bustos Zapata, Nelly; Hernández Moreno, María Angélica; Oyarzún Macchiavello, María Teresa

    2017-03-30

    Introducción: el 27 de junio de 2016 se implementó en Chile la Ley sobre Composición Nutricional de los Alimentos y su Publicidad, que implica rotular el envase de los alimentos procesados, altos en calorías, grasas saturadas, azúcares y sodio.Objetivo: determinar las actitudes de escolares de 8 a 12 años, de distinto nivel socioeconómico (NSE) y estado nutricional, ante el nuevo etiquetado de los alimentos.Métodos: se aplicó una encuesta validada previamente, agregando preguntas sobre los nuevos sellos en los envases de alimentos y bebidas. Se realizó un análisis descriptivo de las variables estudiadas y se determinaron diferencias según NSE y estado nutricional con la prueba de Chi2.Resultados: no se observaron diferencias por género o ciudad. Al consultar sobre los nuevos sellos, el 87,3% de los niños de NSE medio-alto y 78,5% de NSE bajo señaló que les gustaba ser informados del contenido de los alimentos (p < 0,01). Dejarían de comprar los alimentos con sello el 53% de NSE medio-alto y 48% de NSE bajo. Del 14% al 22% seguirían comiendo galletas dulces, bebidas azucaradas, chocolates y papas fritas, sin diferencias por NSE. Los niños de estado nutricional normal y NSE medio-alto dieron mayor importancia a los sellos altos en calorías, grasas saturadas y sodio, y los de NSE bajo al contenido alto en azúcar. Entre los niños con sobrepeso y obesidad, los de NSEmedio-alto consideraron más importantes los 4 sellos que los de NSE bajo.Discusión: estos resultados facilitarán el apoyo educativo y publicitario para favorecer la comprensión y cumplimiento de la Ley.

  18. Soil and Human Interactions in Maya Wetlands

    NASA Astrophysics Data System (ADS)

    Beach, Timothy; Luzzadder-Beach, Sheryl

    2013-04-01

    Since the early 1990s, we have studied Maya interaction with soils in Mexico, Belize, Guatemala, and elsewhere. We studied upland and lowland soils, but here we focus on seasonal or 'Bajo' wetlands and perennial wetlands for different reasons. Around the bajos, the ancient Maya focused on intensive agriculture and habitation despite the difficulties their Vertisol soils posed. For the perennial wetlands, small populations spread diffusely through Mollisol and Histisol landscapes with large scale, intensive agro-ecosystems. These wetlands also represent important repositories for both environmental change and how humans responded in situ to environmental changes. Work analyzing bajo soils has recorded significant diversity but the soil and sediment record shows two main eras of soil instability: the Pleistocene-Holocene transition as rainfall fluctuated and increased and tropical forest pulsed through the region, and the Maya Preclassic to Classic 3000 to 1000 BP as deforestation, land use intensity, and drying waxed and waned. The ancient Maya adapted their bajo soil ecosystems successfully through agro-engineering but they also withdrew in many important places in the Late Preclassic about 2000 BP and Terminal Classic about 1200 BP. We continue to study and debate the importance of perennial wetland agro-ecosystems, but it is now clear that Maya interaction with these soil landscapes was significant and multifaceted. Based on soil excavation and coring with a broad toolkit of soil stratigraphy, chemistry, and paleoecology from 2001 to 2013, our results show the ancient Maya interacted with their wetland soils to maintain cropland for maize, tree crops, arrow root, and cassava against relative sea level rise, increased flooding, and aggradation by gypsum precipitation and sedimentation. We have studied these interactions across an area of 2000 km2 in Northern Belize to understand how Maya response varied and how these soil environments varied over time and distance

  19. Physical Measurements of Water Properties Across the Mouth of the Gulf of California during April 2013 (PESCAR24 Cruise) (Mediciones Fisicas de las Propiedades del Agua a Traves de la Boca del Golfo de California Durante Abril de 2013 (Crucero PESCAR24)

    DTIC Science & Technology

    2013-11-26

    ningún datos del CTD disponible en el lance de subida para la estación 11, se utilizó información del Sistema de Adquisición de Datos en Curso (UDAS... sistema de adquisición de datos MK21 con su hardware asociado, los cuales también fueron adquiridos de Lockheed Martin Sippican. La lista de... sistema de agua de mar no contaminada desde un receptáculo situado junto a la quilla del barco, a unos tres metros bajo la superficie. Estos datos

  20. [Educational status and life expectancy in patients with chronic non-communicable diseases].

    PubMed

    Villarreal-Hernández, Liliana del Sagrario; Romo-Martínez, Jesús Eduardo

    2014-01-01

    INTRODUCCIÓN: una enfermedad crónica no transmisible, el nivel educativo bajo y los bajos ingresos económicos pueden hacer sinergia y contribuir a un mal pronóstico en cuanto a la expectativa de vida esperada. Se estima que alcanzar un mejor nivel de educación hace posible que mejore la expectativa de vida. El objetivo de esta investigación fue explorar esta relación. MÉTODOS: estudio de cohorte retrospectivo realizado del 1 de enero de 1999 al 31 de diciembre de 2011, de individuos que fallecieron por enfermedades crónicas no transmisibles. Se incluyeron 2306 pacientes registrados en el Sistema de Información en Mortalidad de la Unidad de Medicina Familiar 3, Instituto Mexicano del Seguro Social, en Guadalajara, Jalisco. Se registró la edad al momento de la muerte y el nivel educativo. Las pruebas estadísticas aplicadas fueron t de Student y 2. Se calculó el riesgo relativo.

  1. [In Process Citation].

    PubMed

    Durán Agüero, Samuel; Herrera Valenzuela, Tomás; Poblete Aro, Carlos; Durán Acevedo, Angelo; Valdés Badilla, Pablo

    2016-03-25

    Objetivo: determinar los patrones alimentarios de ultramaratonistas chilenos. Métodos: estudio descriptivo transversal, con enfoque cuantitativo. La muestra incluyó 20 ultramaratonistas (n = 3 mujeres), quienes promediaban para la edad 33,0 ± 7,8 años, peso 71,1 ± 6,6 kg y estatura 1,72 ± 0,05 m. Se aplicó una encuesta de hábitos alimentarios validada y un punto de significación de p < 0,05. Resultados: los ultramaratonistas chilenos presentan bajo consumo de alimentos de acuerdo a las porciones recomendadas de frutas, verduras, pescado y leguminosas, y el 75% de ellos consume desayuno diariamente. Se observa ingestas moderadas de bebidas azucaradas, snacks dulces y alcohol, mientras que la ingesta de frituras (65%) corresponde al hábito no saludable más frecuente. Conclusión: los ultramaratonistas chilenos presentan un bajo cumplimiento en las porciones recomendadas de alimentos, pese al gran esfuerzo físico que realizan.

  2. [Dietary factors associated with stroke: a literature review].

    PubMed

    Lopez-Romero, L; Silva-Sieger, F; Gamboa-Delgado, E

    2016-09-01

    Introduccion. El ictus es una condicion cronica no transmisible de alto impacto, producida por diferentes factores, entre los que estan los relacionados con el estilo de vida, de los cuales forman parte los factores dieteticos. Objetivo. Revisar la evidencia existente con relacion a los factores dieteticos asociados al ictus. Desarrollo. Se realizo una revision de la bibliografia de los factores dieteticos y el ictus. Los estudios revisados describen una disminucion del riesgo de ictus, segun el consumo recomendado, hasta del 39% para la dieta mediterranea, el 19% para la dieta DASH, el 10% para las nueces, el 26% para las frutas y verduras, el 31% para el pescado, el 26% para la proteina total, el 9% para los lacteos bajos en grasa y el 18% para el calcio. Por el contrario, describen un aumento del riesgo hasta del 58% para la dieta occidental, el 13% para la carne procesada y el 23% para la sal. En relacion con el consumo de legumbres, huevos y leche entera, los resultados son heterogeneos. Conclusiones. El consumo de nueces, frutas y verduras, pescado, proteina total, lacteos bajos en grasa, calcio y la alta adhesion a las dietas DASH y mediterranea podrian tener efectos protectores para el ictus. Mientras que el alto consumo de carnes rojas y procesadas, sal y la dieta occidental podrian constituir un factor de riesgo. Asimismo, es necesaria una mayor investigacion en relacion con el consumo de legumbres, huevos, leche entera, arroz, patatas y bebidas azucaradas.

  3. Pre-Inca Astronomy in Peru

    NASA Astrophysics Data System (ADS)

    McKim Malville, J.

    Huacas (shrines) and ushnus (ceremonial platforms) are ever-present elements of millennia-old Andean cosmology extending backward to 3100 BCE. Major themes of Pan-Andean cosmology include sacred mountains, the power of water, the solstice sun, as well as shamanic-like movement across the three worlds of the cosmos. Common features of many pre-Inca sites are monumental platforms and sunken circular plazas, and stairways with axes established by bi-lateral symmetries oriented along solstice lines. This style of ritual architecture first appeared in Chupacigarro/Caral, other sites in the Norte Chico area, and Sechin Bajo in the Casma Valley. Ceremonial plazas provided opportunities for public viewing of ritual ceremonies on the tops of platforms, which may have been understood as sacred mountains. Mounds and temples of the Casma Valley, such as Sechin Alto, Sechin Bajo, and Chankillo, developed an explicit astronomy associated with June and December solstices. The ritualistic use of water, which is typically associated with visual astronomy at Inca sites, appeared at Chavin de Huantar and later in Tiwanaku.

  4. An analysis of modern pollen rain from the Maya lowlands of northern Belize

    USGS Publications Warehouse

    Bhattacharya, T.; Beach, T.; Wahl, D.

    2011-01-01

    In the lowland Maya area, pollen records provide important insights into the impact of past human populations and climate change on tropical ecosystems. Despite a long history of regional paleoecological research, few studies have characterized the palynological signatures of lowland ecosystems, a fact which lowers confidence in ecological inferences made from palynological data. We sought to verify whether we could use pollen spectra to reliably distinguish modern ecosystem types in the Maya lowlands of Central America. We collected 23 soil and sediment samples from eight ecosystem types, including upland, riparian, secondary, and swamp (bajo) forests; pine savanna; and three distinct wetland communities. We analyzed pollen spectra with non-metric multidimensional scaling (NMDS), and found significant compositional differences in ecosystem types' pollen spectra. Forested sites had spectra dominated by Moraceae/Urticaceae pollen, while non-forested sites had significant portions of Poaceae, Asteraceae, and Amaranthaceae pollen. Upland, bajo, and riparian forest differed in representation of Cyperaceae, Bactris-type, and Combretaceae/Melastomataceae pollen. High percentages of pine (Pinus), oak (Quercus), and the presence of Byrsonima characterized pine savanna. Despite its limited sample size, this study provides one of the first statistical analyses of modern pollen rain in the Maya lowlands. Our results show that pollen assemblages can accurately reflect differences between ecosystem types, which may help refine interpretations of pollen records from the Maya area. ?? 2010 Elsevier B.V.

  5. Amplificadores en bandas para receptores de uso radioastronómicos

    NASA Astrophysics Data System (ADS)

    Bava, A. J.; Sanz, A. J.

    Está en curso de realización en el IAR un cabezal de receptor, en la frecuencia de 3.3 GHz. Este receptor, conjuntamente con los sistemas de procesamientos actuales del IAR y con los futuros proyectos de procesamientos, permitirán las observaciones de las líneas de la molécula de CH, de gran interés astrofísico, y las observaciones en el continuo que complementarán las realizadas en 1420 MHz. En este trabajo, se presentan el diseño de los amplificadores de bajo ruido, que van a conformar las primeras etapas del receptor de 3.3 GHz. El desarrollo de los mismos se realizó teniendo en cuenta que la temperatura del sistema, según consideraciones observacionales, deberá ser de 60oK. Por tal motivo se realizó un diseño de bajo ruido utilizando como elemento activo un HEMT. Tanto los métodos de diseño, como el circuito final, fueron realizados y comprobados con programas de simulación, permitiendo de esta forma obtener el amplificador deseado.

  6. Leishmaniasis in Colombia. I. Studies on the phlebotomine fauna associated with endemic foci in the Pacific Coast region.

    PubMed

    Travi, B L; Montoya, J; Solarte, Y; Lozano, L; Jaramillo, C

    1988-09-01

    Studies on the phlebotomine fauna related to the leishmaniasis endemic foci of the Colombian Pacific Coast were carried out in the municipalities of Tumaco and Buenaventura. In Inguapí del Guadual, Tumaco, Lutzomyia trapidoi and Lu. gomezi were the predominant anthropophilic species; Lu. panamensis and Lu. hartmanni were less frequent. In Bajo Calima, Buenaventura, Lu. trapidoi represented over 94% of the anthropophilic sandflies. Continuous sampling from 1800 to 0600 hours in Inguapí del Guadual demonstrated that Lu. trapidoi bites mainly at dusk and dawn whereas Lu. gomezi remains active throughout the night. In Inguapí del Guadual, promastigotes were found in 0.1% (2/2, 305) of Lu. trapidoi, 0.2% (3/140) of Lu. gomezi, and 0.2% (1/424) of Lu. panamensis samples collected. In Bajo Calima, 1.9% (8/429) of Lu. trapidoi were found to be infected. Leishmania braziliensis panamensis, the most common Leishmania subspecies in the human population of this endemic focus, was isolated from 1 Lu. trapidoi from Inguapí del Guadual. Parasitological and entomological findings suggest that Lu. trapidoi could be the main vector of Leishmania in these areas, although Lu. gomezi and Lu. panamensis were also predominant.

  7. Bases para la elaboracion de unidades didacticas de calidad en el area de ciencias (Fisica y Quimica 3 deg ESO)

    NASA Astrophysics Data System (ADS)

    Maccioni, Elena Lucia

    Este Trabajo Fin de Master tiene como objeto, el estudio previo de la educacion de la ciencia en la actualidad y mas destacable, del diseno de las unidades didacticas segun las metodologias mas frecuentes aplicadas por los diferentes sistemas educativos en el area de las Ciencias teniendo en cuenta la importancia y el efecto de la psicologia del alumnado y todo ello como no puede ser de otro modo bajo el corse de la Legislacion aplicable, Estatal, Autonomica y europea. Con estos antecedentes, se extrae cuales son las preguntas que deben contestarse en la elaboracion de una unidad didactica de calidad en el contexto, generacional (edad y sexo), del Proyecto Educativo de Centro, y de la Programacion del Departamento, discutiendo y justificando cada uno de los apartados en que estructuradamente dividiremos dicha Unidad, con un formato manejable, util, y dinamico en el tiempo que sea un verdadero instrumento educativo de aula. Teniendo en cuenta estas premisas, se procede a hacer una recopilacion de una misma unidad didactica publicada por diferentes editoriales, elegidas no al azar, sino en funcion de su penetracion editorial en nuestros centros de ESO, siendo las elegidas (SM y Oxford). Las diferentes unidades seleccionadas son analizadas de forma critica, atendiendo a los criterios generales de calidad bajo parametros cientificos y normativos, concluyendo con la aportacion final que es la redaccion de unas pautas cientifico-pedagogicas, para redactar unidades didacticas de calidad en el area de la Ciencias, en concreto en la Asignatura de Fisica y Quimica de 3º de ESO.

  8. Habitus furibundo en el gueto estadounidense1

    PubMed Central

    Bourgois, Philippe; Castrillo, Fernando Montero; Hart, Laurie; Karandinos, George

    2014-01-01

    Resumen Durante cinco años, un torbellino cotidiano de tiroteos, apuñalamientos y asaltos afectó a la venta de drogas al aire libre en el vecindario puertorriqueño de Filadelfia, donde residíamos y conducíamos nuestro trabajo de campo. La industria de los narcóticos ha venido a llenar el vacío que dejó la desindustrialización, convirtiendo al antiguo distrito fabril de la ciudad en un mercado de narcóticos a cielo abierto que emplea en sus niveles más bajos a jóvenes puertorriqueños y cuyos clientes son principalmente heroinómanos blancos de bajos recursos. La capacidad para movilizar la furia asegura el éxito en la economía de las drogas, garantiza protección en las cárceles y le provee un ingreso mínimo a una población de bajos recursos estigmatizada cuyos miembros frecuentemente reciben diagnósticos médicos de discapacidad cognitiva. Muchos residentes buscan alianzas en redes sociales que los comprometen a participar en intercambios solidarios de violencia auxiliar. Una dinámica de acumulación primitiva corporizada mata, hiere, discapacita o encarcela a la mayoría de estos empleados de bajo nivel y a sus clientes. Los inflados márgenes de ganancia alrededor de esta dinámica dependen de la violencia y la coerción. Un habitus furibundo impulsa a los vendedores callejeros a defender violentamente el micro monopolio de poder de sus jefes en la economía subterránea como si fuese un asunto de diversión. Estos miembros de los niveles más bajos de la industria del narcotráfico se apresuran a fraguar transacciones comerciales en ausencia de un marco legal en un ambiente de escasez que sin embargo se ve inundado por enormes flujos de dinero, drogas adictivas y armas automáticas. Tras las drásticas reformas a los programas de seguridad social, la mano izquierda del Estado, en la forma de los servicios sociales, intenta prolongar los subsidios para individuos vulnerables diagnosticándolos como discapacitados cognitivos permanentes

  9. Enhanced Southern Westerly Activity During the Last Glacial Interglacial Transition in SW Patagonia

    NASA Astrophysics Data System (ADS)

    Moreno, P. I.; Villa-Martinez, R. P.; Cardenas, M. L.; Moy, C. M.

    2008-12-01

    Much of the ongoing controversy regarding synchrony or bipolar asynchrony has centered on the timing and structure of temperature changes during the Last Glacial Interglacial Transition (LGIT) in the southern mid- latitudes, in particular the Patagonian region (40°-56°S) of South America. South America is the only continuous continental landmass in the Southern Hemisphere that intersects the entire westerly wind belt and lies in the critical climatic interface between mid- to high latitudes. The region between 50°- 55°S is of particular interest considering its proximity to the polar front and the southern margin of the westerly winds, and the possibility of monitoring paleoclimate changes at or near this important oceanic- atmospheric boundary. Present and past climate studies, including modeling simulations, have emphasized that interactions between changes in the Antarctic Circumpolar Current, the southern westerly winds, sea ice, and the polar front are important drivers for deep ocean circulation changes, variations in atmospheric CO2, and equator-to-pole temperature and pressure gradients. Yet, the behavior of the westerly winds and the adjacent Southern Ocean during the LGIT is still poorly understood despite their fundamental influence on modern hemispheric and global climate. In this study we compare sediment cores from small closed-basin lakes and a bog from the Ultima Esperanza area of SW Patagonia (52°S), an area affected solely by the southern westerlies. Lake sediment cores from three lakes show lacustrine sedimentation over the last 17,000 years. In contrast, the Dumestre bog shows subaerial peat deposition since 15 ka interrupted by a prominent lacustrine phase dated between 14.5-11.5 ka. During this interval palynological records indicate the preponderance of cold-resistant herbs, along with aquatic taxa, followed by a rapid expansion of Nothofagus woodlands/forests, a lake regressive phase in Dumestre, and disappearance of laminated calcite

  10. Towards a common methodology to simulate tree mortality based on ring-width data

    NASA Astrophysics Data System (ADS)

    Cailleret, Maxime; Bigler, Christof; Bugmann, Harald; Davi, Hendrik; Minunno, Francesco; Peltoniemi, Mikko; Martínez-Vilalta, Jordi

    2015-04-01

    Individual mortality is a key process of population and community dynamics, especially for long-lived species such as trees. As the rates of vegetation background mortality and of massive diebacks accelerated during the last decades and would continue in the future due to rising temperature and increasing drought, there is a growing demand of early warning signals that announce that the likelihood of death is very high. If physiological indicators have a high potential to predict tree mortality, their development requires an intensive tree monitoring which cannot be currently done on a representative sample of a population and on several species. An easier approach is to use radial growth data such as tree ring-widths measurements. During the last decades, an increasing number of studies aimed to derive these growth-mortality functions. However, as they followed different approaches concerning the choice of the sampling strategy (number of dead and living trees), of the type of growth explanatory variables (growth level, growth trend variables…), and of the length of the time-window (number of rings before death) used to calculate them, it makes difficult to compare results among studies and a subsequent biological interpretation. We detailed a new methodology for assessing reliable tree-ring based growth-mortality relationships using binomial logistic regression models. As examples we used published tree-ring datasets from Abies alba growing in 13 different sites, and from Nothofagus dombeyi and Quercus petraea located in one single site. Our first approach, based on constant samplings, aims to (1) assess the dependency of growth-mortality relationships on the statistical sampling scheme used; (2) determine the best length of the time-window used to calculate each growth variable; and (3) reveal the presence of intra-specific shifts in growth-mortality relationships. We also followed a Bayesian approach to build the best multi-variable logistic model considering

  11. Abundance and Morphological Effects of Large Woody Debris in Forested Basins of Southern Andes

    NASA Astrophysics Data System (ADS)

    Andreoli, A.; Comiti, F.; Lenzi, M. A.

    2006-12-01

    The Southern Andes mountain range represents an ideal location for studying large woody debris (LWD) in streams draining forested basins thanks to the presence of both pristine and managed woodland, and to the general low level of human alteration of stream corridors. However, no published investigations have been performed so far in such a large region. The investigated sites of this research are three basins (9-13 km2 drainage area, third-order channels) covered by Nothofagus forests: two of them are located in the Southern Chilean Andes (the Tres Arroyos in the Malalcahuello National Reserve and the Rio Toro within the Malleco Natural Reserve) and one basin lies in the Argentinean Tierra del Fuego (the Buena Esperanza basin, near the city of Ushuaia). Measured LWD were all wood pieces larger than 10 cm in diameter and 1 m in length, both in the active channel and in the adjacent active floodplain. Pieces forming log jams were all measured and the geometrical dimensions of jams were taken. Jam type was defined based on Abbe and Montgomery (2003) classification. Sediment stored behind log-steps and valley jams was evaluated approximating the sediment accumulated to a solid wedge whose geometrical dimensions were measured. Additional information relative to each LWD piece were recorded during the field survey: type (log, rootwad, log with rootwads attached), orientation to flow, origin (floated, bank erosion, landslide, natural mortality, harvest residuals) and position (log-step, in-channel, channel-bridging, channel margins, bankfull edge). In the Tres Arroyos, the average LWD volume stored within the bankfull channel is 710 m3 ha-1. The average number of pieces is 1,004 per hectare of bankfull channel area. Log-steps represent about 22% of all steps, whereas the elevation loss due to LWD (log-steps and valley jams) results in 27% loss of the total stream potential energy. About 1,600 m3 of sediment (assuming a porosity of 20%) is stored in the main channel

  12. Transpiration and water use efficiency in native chilean and exotic species, a usefull tool for catchment management?

    NASA Astrophysics Data System (ADS)

    Hervé-Fernández, P.; Oyarzun, C. E.

    2012-04-01

    Land-use and forest cover change play important roles in socio-economic processes and have been linked with water supply and other ecosystem services in various regions of the world. Water yield from watersheds is a major ecosystem service for human activities but has been altered by landscape management superimposed on climatic variability and change. Sustaining ecosystem services important to humans, while providing a dependable water supply for agriculture and urban needs is a major challenge faced by managers of human-dominated or increased antropical effect over watersheds. Since water is mostly consumed by vegetation (i.e: transpiration), which strongly depends on trees physiological characteristics (i.e: foliar area, transpiration capacity) are very important. The quantity of water consumed by plantations is influenced mainly by forest characteristics (species physiology, age and management), catchment water retention capacity and meteorological characteristics. Eventhough in Chile, the forest sector accounts for 3.6% of the gross domestic product (GDP) and 12.5% of total exports (INFOR, 2003), afforestation with fast growing exotic species has ended up being socially and politically questionable because of the supposed impact on the environment and water resources. We present data of trees transpiration and water use efficiency from three headwater catchments: (a) second growth native evergreen forest (Aetoxicon punctatum, Drimys winterii, Gevuina avellana, Laureliopsis philippiana); (b) Eucalyptus globulus plantation, and (c) a mixed native deciduous (Nothofagus obliqua and some evergreen species) forest and Eucalyptus globulus and Acacia melanoxylon plantation located at the Coastal Mountain Range in southern Chile (40°S). Annual transpiration rates ranged from 1.24 ± 0.41 mol•m-2•s-1 (0.022 ± 0.009 L•m-2•s-1) for E. globulus, while the lowest observed was for L. philippiana 0.44 ± 0.31 mol•m-2•s-1 (0.008 ± 0.006 L•m-2•s-1). However

  13. The influence of production conditions, starting material and deposition environment on charcoal alteration in a tropical biome.

    NASA Astrophysics Data System (ADS)

    Ascough, Philippa; Bird, Michael; Meredith, Will; Large, David; Snape, Colin; Manion, Corinne

    2014-05-01

    Natural and anthropogenic burning events are a key link in the global carbon cycle, substantially influencing atmospheric CO2 levels, and consuming c.8700 teragrams yr-1 of dry biomass [1,2,3]. An important result of this process is charcoal, when lignocellulosic structures in biomass (e.g. wood) are converted to aromatic domains with high chemical stability. Charcoal is therefore not readily re-oxidized to CO2, with estimates of 5-7 ky for the half-life of charcoal carbon in soils [3,4]. Charcoal's high carbon content coupled with high environmental resistance has led to the concept of biochar as a valuable means of global carbon sequestration, capable of carbon offsets comparable to annual anthropogenic fuel emissions [5,6,7]. Charcoal is not, however, an environmentally inert substance, and at least some components of charcoal are susceptible to alteration in depositional environments. Despite the importance of charcoal in global carbon cycling, the mechanisms by which charcoal is altered in the environment remain, as yet, poorly understood. This fact limits our ability to properly incorporate both natural environmental charcoal and biochar into global carbon budgets. This study aimed to improve understanding of charcoal alteration in the environment by examining the influence of production conditions, starting material and deposition environment on the physical and chemical characteristics of charcoal at a field site in the Daintree rainforest. These factors have been identified as critical in determining the dynamics of charcoal in depositional environments [8,9] and climatic conditions at the field site (in Tropical Queensland, Australia) are likely to result in extensive alteration of charcoal. Charcoal from wood (Nothofagus spp.), algae (Enteromorpha spp.), and sugarcane (Saccharum spp.) biomass was produced at temperatures over 300-500°C and exposed to conditions of varying pH and vegetation cover. The effect of these variables on charcoal chemistry

  14. Evidence for Repeated Early Miocene Glaciation and the Cutting of Upper Taylor Valley from the Friis Hills, Antarctica

    NASA Astrophysics Data System (ADS)

    Lewis, A.; Ashworth, A. C.; Marchant, D. R.; Hemming, S. R.

    2009-12-01

    The Friis Hills, located at the head of Taylor Valley in the the McMurdo Dry Valleys, hold a sequence of stacked tills at least Early Miocene in age. Sedimentology, clast lithology and bedrock striations indicate these tills were deposited from wet-based glaciers that flowed southeastward down a shallow paleovalley toward the Ferrar trough. Interbedded paleosols, fluvial, and glaciolacustrine deposits register ice-free periods when the valley held small streams and ponds. Exceptionally well-preserved fossil biota suggests mild conditions during at least two of these interglacial episodes. Proglacial lacustrine deposits that include dropstones and debris flows mark the return of glacial conditions but fossil leaves and wood of Nothofagus suggest conditions during the initial phase of ice advance were also relatively mild. Geomorphic relationships show that major valley incision must have taken place after deposition of these sediments as the Friis Hills is today a flat-topped inselberg, about 5 km across, isolated from nearby topography by the deep glacial troughs of the Taylor Valley drainage. A second suite of tills, directly overlying the first, registers a reorganized glacial system with ice streaming eastward, roughly parallel to Taylor Valley. Like the first, these tills were deposited during repeated ice advances but glaciers never fully inundated the Friis Hills and ice-free periods are marked by only weak weathering surfaces and thin glaciolacustrine deposits. We interpret the changing glacial pattern to reflect headward cutting in upper Taylor Valley and the capture of ice from the Ferrar drainage. A volcanic ash interbed dated by Ar-Ar at 19.76 (±0.11) Ma occurs in a Taylor Valley-oriented drift near the eastern edge of the Friis Hills plateau. Based on its stratigraphic position, the older suite of tills and fossil-bearing interbeds are >19.76 Ma. Underlying bedrock striations show that ice flow had been redirected into Taylor Valley by this time. The

  15. [Adherence to a mediterranean diet and sport performance in a elite female athletes futsal population].