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Sample records for natural selection plant

  1. Antiherbivore defenses alter natural selection on plant reproductive traits.

    PubMed

    Thompson, Ken A; Johnson, Marc T J

    2016-04-01

    While many studies demonstrate that herbivores alter selection on plant reproductive traits, little is known about whether antiherbivore defenses affect selection on these traits. We hypothesized that antiherbivore defenses could alter selection on reproductive traits by altering trait expression through allocation trade-offs, or by altering interactions with mutualists and/or antagonists. To test our hypothesis, we used white clover, Trifolium repens, which has a Mendelian polymorphism for the production of hydrogen cyanide-a potent antiherbivore defense. We conducted a common garden experiment with 185 clonal families of T. repens that included cyanogenic and acyanogenic genotypes. We quantified resistance to herbivores, and selection on six floral traits and phenology via male and female fitness. Cyanogenesis reduced herbivory but did not alter the expression of reproductive traits through allocation trade-offs. However, the presence of cyanogenic defenses altered natural selection on petal morphology and the number of flowers within inflorescences via female fitness. Herbivory influenced selection on flowers and phenology via female fitness independently of cyanogenesis. Our results demonstrate that both herbivory and antiherbivore defenses alter natural selection on plant reproductive traits. We discuss the significance of these results for understanding how antiherbivore defenses interact with herbivores and pollinators to shape floral evolution. PMID:26940904

  2. How herbivores coopt plant defenses: natural selection, specialization, and sequestration.

    PubMed

    Petschenka, Georg; Agrawal, Anurag A

    2016-04-01

    We review progress in understanding sequestration by herbivorous insects, the use of plant chemical defenses for their own defense. We incorporate sequestration into the framework of plant-insect coevolution by integrating three hierarchical issues: (1) the relationship between dietary specialization and sequestration of plant defenses, (2) the physiological mechanisms involved in sequestration, and (3) how sequestration evolves via interactions between trophic levels. Sequestration is often associated with specialization, but even specialized sequestration is not an evolutionary dead-end. Despite considerable progress in understanding physiological mechanisms, detailed knowledge of how plant toxins cross the insect gut epithelium is still largely lacking. Sequestration is likely a major vehicle for coevolutionary escalation in speciose plant-insect-predator interactions, suggesting that a strictly bitrophic view is untenable. PMID:27436642

  3. Natural selection on plant resistance to herbivores in the native and introduced range.

    PubMed

    Valverde, Pedro L; Arroyo, Juan; Núñez-Farfán, Juan; Castillo, Guillermo; Calahorra, Adriana; Pérez-Barrales, Rocío; Tapia-López, Rosalinda

    2015-01-01

    When plants are introduced into new regions, the absence of their co-evolved natural enemies can result in lower levels of attack. As a consequence of this reduction in enemy pressure, plant performance may increase and selection for resistance to enemies may decrease. In the present study, we compared leaf damage, plant size and leaf trichome density, as well as the direction and magnitude of selection on resistance and plant size between non-native (Spain) and native (Mexico) populations of Datura stramonium. This species was introduced to Spain about five centuries ago and constitutes an ideal system to test four predictions of the enemy release hypothesis. Compared with native populations, we expected Spanish populations of D. stramonium to have (i) lower levels of foliar damage; (ii) larger plant size; (iii) lower leaf trichome density that is unrelated to foliar damage by herbivores; and (iv) weak or no selection on resistance to herbivores but strong selection on plant size. Our results showed that, on average, plants from non-native populations were significantly less damaged by herbivores, were less pubescent and were larger than those from native populations. We also detected different selection regimes on resistance and plant size between the non-native and native ranges. Positive selection on plant size was detected in both ranges (though it was higher in the non-native area), but consistent positive selection on relative resistance was detected only in the native range. Overall, we suggest that changes in selection pressure on resistance and plant size in D. stramonium in Spain are a consequence of 'release from natural enemies'. PMID:26205526

  4. Natural selection on plant resistance to herbivores in the native and introduced range

    PubMed Central

    Valverde, Pedro L.; Arroyo, Juan; Núñez-Farfán, Juan; Castillo, Guillermo; Calahorra, Adriana; Pérez-Barrales, Rocío; Tapia-López, Rosalinda

    2015-01-01

    When plants are introduced into new regions, the absence of their co-evolved natural enemies can result in lower levels of attack. As a consequence of this reduction in enemy pressure, plant performance may increase and selection for resistance to enemies may decrease. In the present study, we compared leaf damage, plant size and leaf trichome density, as well as the direction and magnitude of selection on resistance and plant size between non-native (Spain) and native (Mexico) populations of Datura stramonium. This species was introduced to Spain about five centuries ago and constitutes an ideal system to test four predictions of the enemy release hypothesis. Compared with native populations, we expected Spanish populations of D. stramonium to have (i) lower levels of foliar damage; (ii) larger plant size; (iii) lower leaf trichome density that is unrelated to foliar damage by herbivores; and (iv) weak or no selection on resistance to herbivores but strong selection on plant size. Our results showed that, on average, plants from non-native populations were significantly less damaged by herbivores, were less pubescent and were larger than those from native populations. We also detected different selection regimes on resistance and plant size between the non-native and native ranges. Positive selection on plant size was detected in both ranges (though it was higher in the non-native area), but consistent positive selection on relative resistance was detected only in the native range. Overall, we suggest that changes in selection pressure on resistance and plant size in D. stramonium in Spain are a consequence of ‘release from natural enemies’. PMID:26205526

  5. Did RNA editing in plant organellar genomes originate under natural selection or through genetic drift?

    PubMed Central

    Jobson, Richard W; Qiu, Yin-Long

    2008-01-01

    Background The C↔U substitution types of RNA editing have been observed frequently in organellar genomes of land plants. Although various attempts have been made to explain why such a seemingly inefficient genetic mechanism would have evolved, no satisfactory explanation exists in our view. In this study, we examined editing patterns in chloroplast genomes of the hornwort Anthoceros formosae and the fern Adiantum capillus-veneris and in mitochondrial genomes of the angiosperms Arabidopsis thaliana, Beta vulgaris and Oryza sativa, to gain an understanding of the question of how RNA editing originated. Results We found that 1) most editing sites were distributed at the 2nd and 1st codon positions, 2) editing affected codons that resulted in larger hydrophobicity and molecular size changes much more frequently than those with little change involved, 3) editing uniformly increased protein hydrophobicity, 4) editing occurred more frequently in ancestrally T-rich sequences, which were more abundant in genes encoding membrane-bound proteins with many hydrophobic amino acids than in genes encoding soluble proteins, and 5) editing occurred most often in genes found to be under strong selective constraint. Conclusion These analyses show that editing mostly affects functionally important and evolutionarily conserved codon positions, codons and genes encoding membrane-bound proteins. In particular, abundance of RNA editing in plant organellar genomes may be associated with disproportionately large percentages of genes in these two genomes that encode membrane-bound proteins, which are rich in hydrophobic amino acids and selectively constrained. These data support a hypothesis that natural selection imposed by protein functional constraints has contributed to selective fixation of certain editing sites and maintenance of the editing activity in plant organelles over a period of more than four hundred millions years. The retention of genes encoding RNA editing activity may be

  6. [Characteristics of Natural Selection in Populations of Nodule Bacteria (Rhizobium leguminosarum) Interacting With Different Host Plants].

    PubMed

    Andronov, E E; Igolkina, A A; Kimeklis, A K; Vorobyov, N I; Provorov, N A

    2015-10-01

    Using high throughput sequencing of the nodA gene, we studied the population dynamics of Rhizobium leguminosarum (bv. viciae, bv. trifolii) in rhizospheric and nodular subpopulations associated with the leguminous plants representing different cross-inoculation groups (Vicia sativa, Lathyrus pratensis of the vetch/vetchling/pea group and Trifolium hybridum of the clover group). The "rhizosphere-nodules" transitions result in either an increase or decrease in the frequencies of 10 of the 23 operational taxonomic units (OTUs) (which were identified with 95% similarity) depending on the symbiotic specificity and phylogenetic positions of OTUs. Statistical and bioinformatical analysis of the population structures suggest that the type of natural selection responsible for these changes may be diversifying at the whole-population level and frequency-dependent at the OTU-specific level, ensuring the divergent evolution of rhizobia interacting with different host species. PMID:27169225

  7. Plants of the Cerrado naturally selected by grazing sheep may have potential for inhibiting development of Haemonchus contortus larva.

    PubMed

    Morais-Costa, Franciellen; Soares, Ana Cláudia Maia; Bastos, Gabriela Almeida; Nunes, Yule Roberta Ferreira; Geraseev, Luciana Castro; Braga, Fernão Castro; Dos Santos Lima, Walter; Duarte, Eduardo Robson

    2015-10-01

    Plant species naturally selected by sheep grazing in the Cerrado region of Brazil were assessed in vitro for activity against Haemonchus contortus. One year of observations showed the plant families in the region exhibiting greatest richness to be Fabaceae, Rubiaceae, Malpighiaceae, Bignoniaceae, Myrtaceae, and Annonaceae. Nine species commonly selected by grazing sheep showed variation in the selectivity index with respect to the dry and rainy seasons. Coproculture was conducted in five replicates of 11 treatments: ivermectin, distilled water, or dehydrated leaves of nine selected plant species administered at 333.3 mg g(-1) fecal culture. The dried powder of Piptadenia viridiflora and Ximenia americana leaves significantly reduced the number of infective larvae compared to the distilled water control. These species showed efficacy of over 85 % despite low concentrations of proanthocyanidin. High-performance liquid chromatography analyses of extracts of these plants showed major peaks of UV spectra characteristic of flavonoids. Those naturally selected plant species with high antihelminthic efficacy show promise for use in diet as an alternative control of H. contortus in sheep. PMID:26085457

  8. Anticancer Activities of Six Selected Natural Compounds of Some Cameroonian Medicinal Plants

    PubMed Central

    Kuete, Victor; Wabo, Hippolyte K.; Eyong, Kenneth O.; Feussi, Michel T.; Wiench, Benjamin; Krusche, Benjamin; Tane, Pierre; Folefoc, Gabriel N.; Efferth, Thomas

    2011-01-01

    Background Natural products are well recognized as sources of drugs in several human ailments. In the present work, we carried out a preliminary screening of six natural compounds, xanthone V1 (1); 2-acetylfuro-1,4-naphthoquinone (2); physcion (3); bisvismiaquinone (4); vismiaquinone (5); 1,8-dihydroxy-3-geranyloxy-6-methylanthraquinone (6) against MiaPaCa-2 pancreatic and CCRF-CEM leukemia cells and their multidrug-resistant subline, CEM/ADR5000. Compounds 1 and 2 were then tested in several other cancer cells and their possible mode of action were investigated. Methodology/Findings The tested compounds were previously isolated from the Cameroonian medicinal plants Vismia laurentii (1, 3, 4, 5 and 6) and Newbouldia laevis (2). The preliminary cytotoxicity results allowed the selection of xanthone V1 and 2-acetylfuro-1,4-naphthoquinone, which were then tested on a panel of cancer cell lines. The study was also extended to the analysis of cell cycle distribution, apoptosis induction, caspase 3/7 activation and the anti-angiogenic properties of xanthone V1 and 2-acetylfuro-1,4-naphthoquinone. IC50 values around or below 4 µg/ml were obtained on 64.29% and 78.57% of the tested cancer cell lines for xanthone V1 and 2-acetylfuro-1,4-naphthoquinone, respectively. The most sensitive cell lines (IC50<1 µg/ml) were breast MCF-7 (to xanthone V1), cervix HeLa and Caski (to xanthone V1 and 2-acetylfuro-1,4-naphthoquinone), leukemia PF-382 and melanoma colo-38 (to 2-acetylfuro-1,4-naphthoquinone). The two compounds showed respectively, 65.8% and 59.6% inhibition of the growth of blood capillaries on the chorioallantoic membrane of quail eggs in the anti-angiogenic assay. Upon treatment with two fold IC50 and after 72 h, the two compounds induced cell cycle arrest in S-phase, and also significant apoptosis in CCRF-CEM leukemia cells. Caspase 3/7 was activated by xanthone V1. Conclusions/Significance The overall results of the present study provided evidence for the

  9. Plant mortality and natural selection may increase biomass yield in switchgrass swards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Switchgrass (Panicum virgatum L.) is an important candidate for bioenergy feedstock production, prompting significant efforts to increase the number of breeding programs and the output of those programs. The objective of this experiment was to determine the potential utility of natural selection for...

  10. Natural Selection on Coding and Noncoding DNA Sequences Is Associated with Virulence Genes in a Plant Pathogenic Fungus

    PubMed Central

    Rech, Gabriel E.; Sanz-Martín, José M.; Anisimova, Maria; Sukno, Serenella A.; Thon, Michael R.

    2014-01-01

    Natural selection leaves imprints on DNA, offering the opportunity to identify functionally important regions of the genome. Identifying the genomic regions affected by natural selection within pathogens can aid in the pursuit of effective strategies to control diseases. In this study, we analyzed genome-wide patterns of selection acting on different classes of sequences in a worldwide sample of eight strains of the model plant-pathogenic fungus Colletotrichum graminicola. We found evidence of selective sweeps, balancing selection, and positive selection affecting both protein-coding and noncoding DNA of pathogenicity-related sequences. Genes encoding putative effector proteins and secondary metabolite biosynthetic enzymes show evidence of positive selection acting on the coding sequence, consistent with an Arms Race model of evolution. The 5′ untranslated regions (UTRs) of genes coding for effector proteins and genes upregulated during infection show an excess of high-frequency polymorphisms likely the consequence of balancing selection and consistent with the Red Queen hypothesis of evolution acting on these putative regulatory sequences. Based on the findings of this work, we propose that even though adaptive substitutions on coding sequences are important for proteins that interact directly with the host, polymorphisms in the regulatory sequences may confer flexibility of gene expression in the virulence processes of this important plant pathogen. PMID:25193312

  11. Demonstrating Natural Selection

    ERIC Educational Resources Information Center

    Hinds, David S.; Amundson, John C.

    1975-01-01

    Describes laboratory exercises with chickens selecting their food from dyed and natural corn kernels as a method of demonstrating natural selection. The procedure is based on the fact that organisms that blend into their surroundings escape predation. (BR)

  12. AfroDb: a select highly potent and diverse natural product library from African medicinal plants.

    PubMed

    Ntie-Kang, Fidele; Zofou, Denis; Babiaka, Smith B; Meudom, Rolande; Scharfe, Michael; Lifongo, Lydia L; Mbah, James A; Mbaze, Luc Meva'a; Sippl, Wolfgang; Efange, Simon M N

    2013-01-01

    Computer-aided drug design (CADD) often involves virtual screening (VS) of large compound datasets and the availability of such is vital for drug discovery protocols. We assess the bioactivity and "drug-likeness" of a relatively small but structurally diverse dataset (containing >1,000 compounds) from African medicinal plants, which have been tested and proven a wide range of biological activities. The geographical regions of collection of the medicinal plants cover the entire continent of Africa, based on data from literature sources and information from traditional healers. For each isolated compound, the three dimensional (3D) structure has been used to calculate physico-chemical properties used in the prediction of oral bioavailability on the basis of Lipinski's "Rule of Five". A comparative analysis has been carried out with the "drug-like", "lead-like", and "fragment-like" subsets, as well as with the Dictionary of Natural Products. A diversity analysis has been carried out in comparison with the ChemBridge diverse database. Furthermore, descriptors related to absorption, distribution, metabolism, excretion and toxicity (ADMET) have been used to predict the pharmacokinetic profile of the compounds within the dataset. Our results prove that drug discovery, beginning with natural products from the African flora, could be highly promising. The 3D structures are available and could be useful for virtual screening and natural product lead generation programs. PMID:24205103

  13. Glutathione transferase from Plasmodium falciparum--interaction with malagashanine and selected plant natural products.

    PubMed

    Mangoyi, Rumbidzai; Hayeshi, Rose; Ngadjui, Bonventure; Ngandeu, Francois; Bezabih, Merhatibebe; Abegaz, Berhanu; Razafimahefa, Solofoniaina; Rasoanaivo, Philippe; Mukanganyama, Stanley

    2010-12-01

    A glutathione transferase (PfGST) isolated from Plasmodium falciparum has been associated with chloroquine resistance. A range of natural products including malagashanine (MG) were screened for inhibition of PfGST by a GST assay with 1-chloro-2,4-dinitrobenzene as a substrate. Only the sesquiterpene (JBC 42C), the bicoumarin (Tral-1), ellagic acid and curcumin, were shown to be potent inhibitors of PfGST with IC(50) values of 8.5, 12, 50 and 69 μM, respectively. Kinetic studies were performed on PfGST using ellagic acid as an inhibitor. Uncompetitive and mixed types of inhibition were obtained for glutathione (GSH) and 1-chloro-2, 4-dinitrobenzene (CDNB). The K(i) for GSH and CDNB were -0.015 μM and 0.011 μM, respectively. Malagashanine (100 µM) only reduced the activity of PfGST to 80% but showed a time-dependent inactivation of PfGST with a t(1/2) of 34 minutes compared to >120 minutes in the absence of MG or in the presence of 5 mM GSH. This work facilitates the understanding of the interaction of PfGST with some plant derived compounds. PMID:20521884

  14. Selected natural and fallout radionuclides in plant foods around the Kudankulam Nuclear Power Project, India.

    PubMed

    Ross, E Mahiban; Raj, Y Lenin; Wesley, S Godwin; Rajan, M P

    2013-01-01

    The activity concentrations of certain radionuclides were quantified in some plant foods cultivated around Kudankulam, where a mega-nuclear power plant is being established. The activity concentrations were found more in the 'pulses' group and were the lowest in 'other vegetable' category. The annual effective dose was computed based on the activity concentration of radionuclides and it was found to be higher due to the consumption of cereals and pulses. Other vegetables, cereals, pulses and nuts recorded high transfer factors for the radionuclide (228)Ra. Fruits, leafy vegetables, tubers and roots, and palm embryo registered high transfer factors for (226)Ra. Group-wise activity concentration, radiation dose to the public and soil-plant-to-transfer factor are discussed in detail. PMID:23017443

  15. Reinventing Natural Selection

    ERIC Educational Resources Information Center

    Geraedts, Caspar L.; Boersma, Kerst Th.

    2006-01-01

    Although many research studies report students' Lamarckian misconceptions, only a few studies present learning and teaching strategies that focus on the successful development of the concept of natural selection. The learning and teaching strategy for upper secondary students (aged 15-16) presented in this study conducted in The Netherlands is…

  16. Natural selection and neutral evolution jointly drive population divergence between alpine and lowland ecotypes of the allopolyploid plant Anemone multifida (Ranunculaceae).

    PubMed

    McEwen, Jamie R; Vamosi, Jana C; Rogers, Sean M

    2013-01-01

    Population differentiation can be driven in large part by natural selection, but selectively neutral evolution can play a prominent role in shaping patters of population divergence. The decomposition of the evolutionary history of populations into the relative effects of natural selection and selectively neutral evolution enables an understanding of the causes of population divergence and adaptation. In this study, we examined heterogeneous genomic divergence between alpine and lowland ecotypes of the allopolyploid plant, Anemone multifida. Using peak height and dominant AFLP data, we quantified population differentiation at non-outlier (neutral) and outlier loci to determine the potential contribution of natural selection and selectively neutral evolution to population divergence. We found 13 candidate loci, corresponding to 2.7% of loci, with signatures of divergent natural selection between alpine and lowland populations and between alpine populations (Fst  = 0.074-0.445 at outlier loci), but neutral population differentiation was also evident between alpine populations (FST  = 0.041-0.095 at neutral loci). By examining population structure at both neutral and outlier loci, we determined that the combined effects of selection and neutral evolution are associated with the divergence of alpine populations, which may be linked to extreme abiotic conditions and isolation between alpine sites. The presence of outlier levels of genetic variation in structured populations underscores the importance of separately analyzing neutral and outlier loci to infer the relative role of divergent natural selection and neutral evolution in population divergence. PMID:23874801

  17. Natural Selection and Neutral Evolution Jointly Drive Population Divergence between Alpine and Lowland Ecotypes of the Allopolyploid Plant Anemone multifida (Ranunculaceae)

    PubMed Central

    McEwen, Jamie R.; Vamosi, Jana C.; Rogers, Sean M.

    2013-01-01

    Population differentiation can be driven in large part by natural selection, but selectively neutral evolution can play a prominent role in shaping patters of population divergence. The decomposition of the evolutionary history of populations into the relative effects of natural selection and selectively neutral evolution enables an understanding of the causes of population divergence and adaptation. In this study, we examined heterogeneous genomic divergence between alpine and lowland ecotypes of the allopolyploid plant, Anemone multifida. Using peak height and dominant AFLP data, we quantified population differentiation at non-outlier (neutral) and outlier loci to determine the potential contribution of natural selection and selectively neutral evolution to population divergence. We found 13 candidate loci, corresponding to 2.7% of loci, with signatures of divergent natural selection between alpine and lowland populations and between alpine populations (Fst  = 0.074–0.445 at outlier loci), but neutral population differentiation was also evident between alpine populations (FST  = 0.041–0.095 at neutral loci). By examining population structure at both neutral and outlier loci, we determined that the combined effects of selection and neutral evolution are associated with the divergence of alpine populations, which may be linked to extreme abiotic conditions and isolation between alpine sites. The presence of outlier levels of genetic variation in structured populations underscores the importance of separately analyzing neutral and outlier loci to infer the relative role of divergent natural selection and neutral evolution in population divergence. PMID:23874801

  18. Naturally selecting solutions

    PubMed Central

    Manning, Timmy; Sleator, Roy D; Walsh, Paul

    2013-01-01

    For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems. PMID:23222169

  19. Grandmothering and natural selection

    PubMed Central

    Kachel, A. Friederike; Premo, L. S.; Hublin, Jean-Jacques

    2011-01-01

    Humans are unique among primates in that women regularly outlive their reproductive period by decades. The grandmother hypothesis proposes that natural selection increased the length of the human post-menopausal period—and, thus, extended longevity—as a result of the inclusive fitness benefits of grandmothering. However, it has yet to be demonstrated that the inclusive fitness benefits associated with grandmothering are large enough to warrant this explanation. Here, we show that the inclusive fitness benefits are too small to affect the evolution of longevity under a wide range of conditions in simulated populations. This is due in large part to the relatively weak selection that applies to women near or beyond the end of their reproductive period. However, we find that grandmothers can facilitate the evolution of a shorter reproductive period when their help decreases the weaning age of their matrilineal grandchildren. Because selection favours a shorter reproductive period in the presence of shorter interbirth intervals, this finding holds true for any form of allocare that helps mothers resume cycling more quickly. We conclude that while grandmothering is unlikely to explain human-like longevity, allocare could have played an important role in shaping other unique aspects of human life history, such as a later age at first birth and a shorter female reproductive period. PMID:20739319

  20. Modeling Natural Selection

    ERIC Educational Resources Information Center

    Bogiages, Christopher A.; Lotter, Christine

    2011-01-01

    In their research, scientists generate, test, and modify scientific models. These models can be shared with others and demonstrate a scientist's understanding of how the natural world works. Similarly, students can generate and modify models to gain a better understanding of the content, process, and nature of science (Kenyon, Schwarz, and Hug…

  1. A Natural Selection Game.

    ERIC Educational Resources Information Center

    Tashiro, Mark E.

    1984-01-01

    Provides rules for a game which simulates selection pressures on a hominid group. Objectives include an appreciation of how selectivity works, an understanding of how abiotic factors are able to influence a population, and how interactions within the population can influence the group. (JM)

  2. A quantum of natural selection

    NASA Astrophysics Data System (ADS)

    Lloyd, Seth

    2009-03-01

    The modern evolutionary synthesis, which marries Darwin's theory of natural selection with Mendel's genetics, was developed around the same time as quantum mechanics. Is there any connection between the two?

  3. Natural Selection Promotes Antigenic Evolvability

    PubMed Central

    Graves, Christopher J.; Ros, Vera I. D.; Stevenson, Brian; Sniegowski, Paul D.; Brisson, Dustin

    2013-01-01

    The hypothesis that evolvability - the capacity to evolve by natural selection - is itself the object of natural selection is highly intriguing but remains controversial due in large part to a paucity of direct experimental evidence. The antigenic variation mechanisms of microbial pathogens provide an experimentally tractable system to test whether natural selection has favored mechanisms that increase evolvability. Many antigenic variation systems consist of paralogous unexpressed ‘cassettes’ that recombine into an expression site to rapidly alter the expressed protein. Importantly, the magnitude of antigenic change is a function of the genetic diversity among the unexpressed cassettes. Thus, evidence that selection favors among-cassette diversity is direct evidence that natural selection promotes antigenic evolvability. We used the Lyme disease bacterium, Borrelia burgdorferi, as a model to test the prediction that natural selection favors amino acid diversity among unexpressed vls cassettes and thereby promotes evolvability in a primary surface antigen, VlsE. The hypothesis that diversity among vls cassettes is favored by natural selection was supported in each B. burgdorferi strain analyzed using both classical (dN/dS ratios) and Bayesian population genetic analyses of genetic sequence data. This hypothesis was also supported by the conservation of highly mutable tandem-repeat structures across B. burgdorferi strains despite a near complete absence of sequence conservation. Diversification among vls cassettes due to natural selection and mutable repeat structures promotes long-term antigenic evolvability of VlsE. These findings provide a direct demonstration that molecular mechanisms that enhance evolvability of surface antigens are an evolutionary adaptation. The molecular evolutionary processes identified here can serve as a model for the evolution of antigenic evolvability in many pathogens which utilize similar strategies to establish chronic infections

  4. Natural selection and mechanistic regularity.

    PubMed

    DesAutels, Lane

    2016-06-01

    In this article, I address the question of whether natural selection operates regularly enough to qualify as a mechanism of the sort characterized by Machamer, Darden, and Craver (2000). Contrary to an influential critique by Skipper and Millstein (2005), I argue that natural selection can be seen to be regular enough to qualify as an MDC mechanism just fine-as long as we pay careful attention to some important distinctions regarding mechanistic regularity and abstraction. Specifically, I suggest that when we distinguish between process vs. product regularity, mechanism-internal vs. mechanism-external sources of irregularity, and abstract vs. concrete regularity, we can see that natural selection is only irregular in senses that are unthreatening to its status as an MDC mechanism. PMID:26921876

  5. Analyzing plant defenses in nature

    PubMed Central

    Kautz, Stefanie; Heil, Martin; Hegeman, Adrian D

    2009-01-01

    A broad range of chemical plant defenses against herbivores has been studied extensively under laboratory conditions. In many of these cases there is still little understanding of their relevance in nature. In natural systems, functional analyses of plant traits are often complicated by an extreme variability, which affects the interaction with higher trophic levels. Successful analyses require consideration of the numerous sources of variation that potentially affect the plant trait of interest. In our recent study on wild lima bean (Phaseolus lunatus L.) in South Mexico, we applied an integrative approach combining analyses for quantitative correlations of cyanogenic potential (HCNp; the maximum amount of cyanide that can be released from a given tissue) and herbivory in the field with subsequent feeding trials under controlled conditions. This approach allowed us to causally explain the consequences of quantitative variation of HCNp on herbivore-plant interactions in nature and highlights the importance of combining data obtained in natural systems with analyses under controlled conditions. PMID:19820300

  6. Natural Selection in Large Populations

    NASA Astrophysics Data System (ADS)

    Desai, Michael

    2011-03-01

    I will discuss theoretical and experimental approaches to the evolutionary dynamics and population genetics of natural selection in large populations. In these populations, many mutations are often present simultaneously, and because recombination is limited, selection cannot act on them all independently. Rather, it can only affect whole combinations of mutations linked together on the same chromosome. Methods common in theoretical population genetics have been of limited utility in analyzing this coupling between the fates of different mutations. In the past few years it has become increasingly clear that this is a crucial gap in our understanding, as sequence data has begun to show that selection appears to act pervasively on many linked sites in a wide range of populations, including viruses, microbes, Drosophila, and humans. I will describe approaches that combine analytical tools drawn from statistical physics and dynamical systems with traditional methods in theoretical population genetics to address this problem, and describe how experiments in budding yeast can help us directly observe these evolutionary dynamics.

  7. Symbiogenesis, natural selection, and the dynamic Earth.

    PubMed

    Kutschera, U

    2009-08-01

    One century ago, Constantin S. Mereschkowsky introduced the symbiogenesis theory for the origin of chloroplasts from ancient cyanobacteria which was later supplemented by Ivan E. Wallin's proposal that mitochondria evolved from once free-living bacteria. Today, this Mereschkowsky-Wallin principle of symbiogenesis, which is also known as the serial primary endosymbiosis theory, explains the evolutionary origin of eukaryotic cells and hence the emergence of all eukaryotes (protists, fungi, animals and plants). In 1858, the concept of natural selection was described independently by Charles Darwin and Alfred R. Wallace. In the same year, Antonio Snider-Pellegrini proposed the idea of shifting continents, which was later expanded by Alfred Wegener, who published his theory of continental drift eight decades ago. Today, directional selection is accepted as the major cause of adaptive evolution within natural populations of micro- and macro-organisms and the theory of the dynamic Earth (plate tectonics) is well supported. In this article, I combine the processes and principles of symbiogenesis, natural selection and the dynamic Earth and propose an integrative 'synade-model' of macroevolution which takes into account organisms from all five Kingdoms of life. PMID:19399544

  8. Probabilities of Natural Events Occurring at Savannah River Plant

    SciTech Connect

    Huang, J.C.

    2001-07-17

    This report documents the comprehensive evaluation of probability models of natural events which are applicable to Savannah River Plant. The probability curves selected for these natural events are recommended to be used by all SRP/SRL safety analysts. This will ensure a consistency in analysis methodology for postulated SAR incidents involving natural phenomena.

  9. Relative contribution of oxygenated hydrocarbons to the total biogenic VOC emissions of selected mid-European agricultural and natural plant species

    NASA Astrophysics Data System (ADS)

    König, Georg; Brunda, Monika; Puxbaum, Hans; Hewitt, C. Nicholas; Duckham, S. Craig; Rudolph, Jochen

    Emission rates of more than 50 individual VOCs were determined for eight plant species and three different types of grass land typical for natural deciduous and agricultural vegetation in Austria. In addition to the emissions of isoprene and monoterpenes, 33 biogenic oxygenated volatile organic compounds (BOVOCs) were detected. Of these, 2-methyl-l-propanol, 1-butanal, 2-butanal, 1-pentanol, 3-pentanol, 1-hexanol, 6-methyl-5-hepten-2-one, butanal and ethylhexylacetate were observed for the first time as plant emissions. In terms of prevalence of one of the groups of emitted VOCs (isoprene, terpenes, BOVOCs) the grain plants wheat and rye, grape, oilseed rape and the decidous trees hombeam and birch could be classified as "BOVOC"-emitters. For the grass plots examined, BOVOCs and terpenes appear to be of equal importance. The emission rates of the total assigned organic plant emissions ranged from 0.01 μ g -1 h -1 for wheat to 0.8 μg g -1 h -1 for oak (based on dry leaf weight). Intercomparison with available data from other studies show that our emission rates are rather at the lower end of reported ranges. The influence of the stage of growth was examined for rye, rape (comparing emissions of blossoming and nonblossoming plants) and for grape (with and without fruit). Emission rate differences for different stages of growth varied from nondetectable for blossoming and nonblossoming rye to a factor of six for the grape with fruits vs grape without fruits (emission rate based on dry leaf weight). The major decidous tree in Austria (beech) is a terpene emitter, with the contribution of BOVOCs below 5% of the total assigned emissions of 0.2 μg g -1 h -1 for the investigations of 20°C.

  10. Marketing time predicts naturalization of horticultural plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Horticulture is an important source of naturalized plants, but little is known about naturalization frequencies and potential patterns of naturalization in horticultural plants. We analyzed a unique set of data derived from the detailed sales catalogs (1886-1930) of the most important early Florida ...

  11. Plant Natural Products Targeting Bacterial Virulence Factors.

    PubMed

    Silva, Laura Nunes; Zimmer, Karine Rigon; Macedo, Alexandre José; Trentin, Danielle Silva

    2016-08-24

    Decreased antimicrobial efficiency has become a global public health issue. The paucity of new antibacterial drugs is evident, and the arsenal against infectious diseases needs to be improved urgently. The selection of plants as a source of prototype compounds is appropriate, since plant species naturally produce a wide range of secondary metabolites that act as a chemical line of defense against microorganisms in the environment. Although traditional approaches to combat microbial infections remain effective, targeting microbial virulence rather than survival seems to be an exciting strategy, since the modulation of virulence factors might lead to a milder evolutionary pressure for the development of resistance. Additionally, anti-infective chemotherapies may be successfully achieved by combining antivirulence and conventional antimicrobials, extending the lifespan of these drugs. This review presents an updated discussion of natural compounds isolated from plants with chemically characterized structures and activity against the major bacterial virulence factors: quorum sensing, bacterial biofilms, bacterial motility, bacterial toxins, bacterial pigments, bacterial enzymes, and bacterial surfactants. Moreover, a critical analysis of the most promising virulence factors is presented, highlighting their potential as targets to attenuate bacterial virulence. The ongoing progress in the field of antivirulence therapy may therefore help to translate this promising concept into real intervention strategies in clinical areas. PMID:27437994

  12. Selected Landscape Plants. Slide Script.

    ERIC Educational Resources Information Center

    McCann, Kevin

    This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with commercially important woody ornamental landscape plants. Included in the script are narrations for use with a total of 253 slides illustrating 92 different plants. Several slides are used to illustrate each plant: besides a view of…

  13. How To Select and Plant a Tree.

    ERIC Educational Resources Information Center

    Fazio, James R., Ed.

    1991-01-01

    This bulletin furnishes information about selecting and planting trees. The tree selection process includes being aware of the physical characteristics of bare root seedlings, containerized seedlings, balled and burlapped, or potted trees and determining the proper size and root ball proportions. The section on tree planting discusses how to: (1)…

  14. Plant tendrils: Nature's hygroscopic springs

    NASA Astrophysics Data System (ADS)

    Gerbode, Sharon; Puzey, Joshua; McCormick, Andrew; Mahadevan, L.

    2012-02-01

    Plant tendrils are specialized climbing organs that have fascinated biologists and physicists alike for centuries. Initially straight tendrils attach at the tip to an elevated rigid support and then winch the plant upward by coiling into a helical morphology characterized by two helices of opposite handedness connected by a helical perversion. In his renowned treatise on twining and tendril-bearing plants, Charles Darwin surmised that coiled tendrils serve as soft, springy attachments for the climbing plant. Yet, the true effect of the perverted helical shape of a coiled plant tendril has not been fully revealed. Using a combination of experiments on Cucurbitaceae tendrils, physical models constructed from strained rubber sheets, and numerical models of helical perversions, we have uncovered that tendril coiling occurs via anisotropic shrinkage of a strip of specialized cells in the interior of the tendril. Furthermore, variations in the mechanical behavior of tendrils as they become drier and ``woodier'' adds a new twist to the story of tendril coiling.

  15. SELECTING PLANT SPECIES FOR PESTICIDE REGISTRATION TESTS

    EPA Science Inventory

    Current test protocols used by the US EPA for the registration of pesticides examines plant responses of 10 crop species but may not examine regionally important native plants or crops. In order to test the efficiency of current test protocols we selected six native plant species...

  16. Genomic selection in plant breeding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genomic selection (GS) is a method to predict the genetic value of selection candidates based on the genomic estimated breeding value (GEBV) predicted from high-density markers positioned throughout the genome. Unlike marker-assisted selection, the GEBV is based on all markers including both minor ...

  17. Evaluation of antioxidant capacity of 13 plant extracts by three different methods: cluster analyses applied for selection of the natural extracts with higher antioxidant capacity to replace synthetic antioxidant in lamb burgers.

    PubMed

    Fernandes, R P P; Trindade, M A; Tonin, F G; Lima, C G; Pugine, S M P; Munekata, P E S; Lorenzo, J M; de Melo, M P

    2016-01-01

    The aims of this study were: to evaluate the total equivalent antioxidant capacities (TEAC) and phenolic contents of 13 plants extracts; to select the most promising extracts regarding reducing activity using cluster analysis multivariate statistical technique; and to analyse evaluate sensory acceptance of lamb burgers produced with the most promising natural antioxidants replacing sodium erythorbate. Plant extracts were evaluated regarding TEAC by DPPH(•) and FRAP methods, and total phenolics contents by Folin-Ciocalteau assay. The TEAC values ranged from 0.50 to 9.06 g trolox/100 g dry weight (dw) and from 43.6 to 472.32 μmol trolox/g dw for DPPH(•) and FRAP methods, respectively, and the total phenolic contents from 5.98 to 74.01 mg GAE/g dw. Extracts from Origanum vulgare, Melissa officinalis, Origanum majorana L. and Rosmarinus officinalis were grouped as the ones with higher antioxidant capacities by cluster analysis. All burgers produced with each one of these four plant extracts or with sodium erythorbate showed no differences (P > 0.05) regarding consumers' sensory acceptance. In conclusion, it is possible to replace sodium erythorbate in lamb burgers by any of the four natural extracts selected without compromising sensory acceptance of this meat product. PMID:26787964

  18. Evolutionary ecology of plant-microbe interactions: soil microbial structure alters selection on plant traits.

    PubMed

    Lau, Jennifer A; Lennon, Jay T

    2011-10-01

    • Below-ground microbial communities influence plant diversity, plant productivity, and plant community composition. Given these strong ecological effects, are interactions with below-ground microbes also important for understanding natural selection on plant traits? • Here, we manipulated below-ground microbial communities and the soil moisture environment on replicated populations of Brassica rapa to examine how microbial community structure influences selection on plant traits and mediates plant responses to abiotic environmental stress. • In soils with experimentally simplified microbial communities, plants were smaller, had reduced chlorophyll content, produced fewer flowers, and were less fecund when compared with plant populations grown in association with more complex soil microbial communities. Selection on plant growth and phenological traits also was stronger when plants were grown in simplified, less diverse soil microbial communities, and these effects typically were consistent across soil moisture treatments. • Our results suggest that microbial community structure affects patterns of natural selection on plant traits. Thus, the below-ground microbial community can influence evolutionary processes, just as recent studies have demonstrated that microbial diversity can influence plant community and ecosystem processes. PMID:21658184

  19. Natural Selection in a Petri Dish.

    ERIC Educational Resources Information Center

    McCarty, Robbie V.; Marek, Edmund A.

    1997-01-01

    Presents an activity to teach natural selection that involves students in a microbiological investigation. Students discover that a change in environmental conditions tests a species' range of adaptations. (DDR)

  20. Can natural selection favour altruism between species?

    PubMed

    Wyatt, G A K; West, S A; Gardner, A

    2013-09-01

    Darwin suggested that the discovery of altruism between species would annihilate his theory of natural selection. However, it has not been formally shown whether between-species altruism can evolve by natural selection, or why this could never happen. Here, we develop a spatial population genetic model of two interacting species, showing that indiscriminate between species helping can be favoured by natural selection. We then ask if this helping behaviour constitutes altruism between species, using a linear-regression analysis to separate the total action of natural selection into its direct and indirect (kin selected) components. We show that our model can be interpreted in two ways, as either altruism within species, or altruism between species. This ambiguity arises depending on whether or not we treat genes in the other species as predictors of an individual's fitness, which is equivalent to treating these individuals as agents (actors or recipients). Our formal analysis, which focuses upon evolutionary dynamics rather than agents and their agendas, cannot resolve which is the better approach. Nonetheless, because a within-species altruism interpretation is always possible, our analysis supports Darwin's suggestion that natural selection does not favour traits that provide benefits exclusively to individuals of other species. PMID:23848844

  1. Comparing Patterns of Natural Selection across Species Using Selective Signatures

    SciTech Connect

    Shapiro, Jesse; Alm, Eric J.

    2007-12-01

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 c-proteobacterial species. We describe the pattern of fast or slow evolution across species as the"selective signature" of a gene. Selective signatures represent aprofile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example,glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell.

  2. Comparing Patterns of Natural Selection Across Species Using Selective Signatures

    SciTech Connect

    Alm, Eric J.; Shapiro, B. Jesse; Alm, Eric J.

    2007-12-18

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 gamma-proteobacterial species. We describe the pattern of fast or slow evolution across species as the 'selective signature' of a gene. Selective signatures represent a profile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example, glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell.

  3. Naturally Occuring Fish Poisons from Plants

    NASA Astrophysics Data System (ADS)

    Cannon, Jonathan G.; Burton, Robert A.; Wood, Steven G.; Owen, Noel L.

    2004-10-01

    Since prehistoric times, cultures throughout the world have used piscicidal (fish poisoning) plants for fishing. In recent times, scientists have identified many of the plant compounds responsible for killing the fish and have found that these compounds possess other important biological properties, such as insecticidal and anti-cancer activities. This article reviews some of the chemical research that has been performed on naturally occurring fish poisons, including plant sources, methods of use, toxicity, and mechanisms of action of piscicides.

  4. Natural selection drives chemical resistance of Datura stramonium.

    PubMed

    Miranda-Pérez, Adán; Castillo, Guillermo; Hernández-Cumplido, Johnattan; Valverde, Pedro L; Borbolla, María; Cruz, Laura L; Tapia-López, Rosalinda; Fornoni, Juan; Flores-Ortiz, César M; Núñez-Farfán, Juan

    2016-01-01

    Plant resistance to herbivores involves physical and chemical plant traits that prevent or diminish damage by herbivores, and hence may promote coevolutionary arm-races between interacting species. Although Datura stramonium's concentration of tropane alkaloids is under selection by leaf beetles, it is not known whether chemical defense reduces seed predation by the specialist weevil, Trichobaris soror, and if it is evolving by natural selection. We measured infestation by T. soror as well as the concentration of the plants' two main tropane alkaloids in 278 D. stramonium plants belonging to 31 populations in central Mexico. We assessed whether the seed predator exerted preferences on the levels of both alkaloids and whether they affect plant fitness. Results show great variation across populations in the concentration of scopolamine and atropine in both leaves and seeds of plants of D. stramonium, as well as in the intensity of infestation and the proportion of infested fruits by T. soror. The concentration of scopolamine in seeds and leaves are negatively associated across populations. We found that scopolamine concentration increases plant fitness. Our major finding was the detection of a positive relationship between the population average concentrations of scopolamine with the selection differentials of scopolamine. Such spatial variation in the direction and intensity of selection on scopolamine may represent a coevolutionary selective mosaic. Our results support the view that variation in the concentration of scopolamine among-populations of D. stramonium in central Mexico is being driven, in part, by selection exerted by T. soror, pointing an adaptive role of tropane alkaloids in this plant species. PMID:27114866

  5. The Signatures of Selection for Translational Accuracy in Plant Genes

    PubMed Central

    Porceddu, Andrea; Zenoni, Sara; Camiolo, Salvatore

    2013-01-01

    Little is known about the natural selection of synonymous codons within the coding sequences of plant genes. We analyzed the distribution of synonymous codons within plant coding sequences and found that preferred codons tend to encode the more conserved and functionally important residues of plant proteins. This was consistent among several synonymous codon families and applied to genes with different expression profiles and functions. Most of the randomly chosen alternative sets of codons scored weaker associations than the actual sets of preferred codons, suggesting that codon position within plant genes and codon usage bias have coevolved to maximize translational accuracy. All these findings are consistent with the mistranslation-induced protein misfolding theory, which predicts the natural selection of highly preferred codons more frequently at sites where translation errors could compromise protein folding or functionality. Our results will provide an important insight in future studies of protein folding, molecular evolution, and transgene design for optimal expression. PMID:23695187

  6. Midbrain auditory selectivity to natural sounds.

    PubMed

    Wohlgemuth, Melville J; Moss, Cynthia F

    2016-03-01

    This study investigated auditory stimulus selectivity in the midbrain superior colliculus (SC) of the echolocating bat, an animal that relies on hearing to guide its orienting behaviors. Multichannel, single-unit recordings were taken across laminae of the midbrain SC of the awake, passively listening big brown bat, Eptesicus fuscus. Species-specific frequency-modulated (FM) echolocation sound sequences with dynamic spectrotemporal features served as acoustic stimuli along with artificial sound sequences matched in bandwidth, amplitude, and duration but differing in spectrotemporal structure. Neurons in dorsal sensory regions of the bat SC responded selectively to elements within the FM sound sequences, whereas neurons in ventral sensorimotor regions showed broad response profiles to natural and artificial stimuli. Moreover, a generalized linear model (GLM) constructed on responses in the dorsal SC to artificial linear FM stimuli failed to predict responses to natural sounds and vice versa, but the GLM produced accurate response predictions in ventral SC neurons. This result suggests that auditory selectivity in the dorsal extent of the bat SC arises through nonlinear mechanisms, which extract species-specific sensory information. Importantly, auditory selectivity appeared only in responses to stimuli containing the natural statistics of acoustic signals used by the bat for spatial orientation-sonar vocalizations-offering support for the hypothesis that sensory selectivity enables rapid species-specific orienting behaviors. The results of this study are the first, to our knowledge, to show auditory spectrotemporal selectivity to natural stimuli in SC neurons and serve to inform a more general understanding of mechanisms guiding sensory selectivity for natural, goal-directed orienting behaviors. PMID:26884152

  7. Midbrain auditory selectivity to natural sounds

    PubMed Central

    Moss, Cynthia F.

    2016-01-01

    This study investigated auditory stimulus selectivity in the midbrain superior colliculus (SC) of the echolocating bat, an animal that relies on hearing to guide its orienting behaviors. Multichannel, single-unit recordings were taken across laminae of the midbrain SC of the awake, passively listening big brown bat, Eptesicus fuscus. Species-specific frequency-modulated (FM) echolocation sound sequences with dynamic spectrotemporal features served as acoustic stimuli along with artificial sound sequences matched in bandwidth, amplitude, and duration but differing in spectrotemporal structure. Neurons in dorsal sensory regions of the bat SC responded selectively to elements within the FM sound sequences, whereas neurons in ventral sensorimotor regions showed broad response profiles to natural and artificial stimuli. Moreover, a generalized linear model (GLM) constructed on responses in the dorsal SC to artificial linear FM stimuli failed to predict responses to natural sounds and vice versa, but the GLM produced accurate response predictions in ventral SC neurons. This result suggests that auditory selectivity in the dorsal extent of the bat SC arises through nonlinear mechanisms, which extract species-specific sensory information. Importantly, auditory selectivity appeared only in responses to stimuli containing the natural statistics of acoustic signals used by the bat for spatial orientation—sonar vocalizations—offering support for the hypothesis that sensory selectivity enables rapid species-specific orienting behaviors. The results of this study are the first, to our knowledge, to show auditory spectrotemporal selectivity to natural stimuli in SC neurons and serve to inform a more general understanding of mechanisms guiding sensory selectivity for natural, goal-directed orienting behaviors. PMID:26884152

  8. Natural selection. IV. The Price equation*

    PubMed Central

    Frank, Steven A.

    2012-01-01

    The Price equation partitions total evolutionary change into two components. The first component provides an abstract expression of natural selection. The second component subsumes all other evolutionary processes, including changes during transmission. The natural selection component is often used in applications. Those applications attract widespread interest for their simplicity of expression and ease of interpretation. Those same applications attract widespread criticism by dropping the second component of evolutionary change and by leaving unspecified the detailed assumptions needed for a complete study of dynamics. Controversies over approximation and dynamics have nothing to do with the Price equation itself, which is simply a mathematical equivalence relation for total evolutionary change expressed in an alternative form. Disagreements about approach have to do with the tension between the relative valuation of abstract versus concrete analyses. The Price equation’s greatest value has been on the abstract side, particularly the invariance relations that illuminate the understanding of natural selection. Those abstract insights lay the foundation for applications in terms of kin selection, information theory interpretations of natural selection, and partitions of causes by path analysis. I discuss recent critiques of the Price equation by Nowak and van Veelen. PMID:22487312

  9. Natural and Sexual Selection on Many Loci

    PubMed Central

    Barton, N. H.; Turelli, M.

    1991-01-01

    A method is developed that describes the effects on an arbitrary number of autosomal loci of selection on haploid and diploid stages, of nonrandom mating between haploid individuals, and of recombination. We provide exact recursions for the dynamics of allele frequencies and linkage disequilibria (nonrandom associations of alleles across loci). When selection is weak relative to recombination, our recursions provide simple approximations for the linkage disequilibria among arbitrary combinations of loci. We show how previous models of sex-independent natural selection on diploids, assortative mating between haploids, and sexual selection on haploids can be analyzed in this framework. Using our weak-selection approximations, we derive new results concerning the coevolution of male traits and female preferences under natural and sexual selection. In particular, we provide general expressions for the intensity of linkage-disequilibrium induced selection experienced by loci that contribute to female preferences for specific male traits. Our general results support the previous observation that these indirect selection forces are so weak that they are unlikely to dominate the evolution of preference-producing loci. PMID:2016044

  10. Natural selection drives chemical resistance of Datura stramonium

    PubMed Central

    Miranda-Pérez, Adán; Castillo, Guillermo; Hernández-Cumplido, Johnattan; Valverde, Pedro L.; Borbolla, María; Cruz, Laura L.; Tapia-López, Rosalinda; Fornoni, Juan; Flores-Ortiz, César M.

    2016-01-01

    Plant resistance to herbivores involves physical and chemical plant traits that prevent or diminish damage by herbivores, and hence may promote coevolutionary arm-races between interacting species. Although Datura stramonium’s concentration of tropane alkaloids is under selection by leaf beetles, it is not known whether chemical defense reduces seed predation by the specialist weevil, Trichobaris soror, and if it is evolving by natural selection. We measured infestation by T. soror as well as the concentration of the plants’ two main tropane alkaloids in 278 D. stramonium plants belonging to 31 populations in central Mexico. We assessed whether the seed predator exerted preferences on the levels of both alkaloids and whether they affect plant fitness. Results show great variation across populations in the concentration of scopolamine and atropine in both leaves and seeds of plants of D. stramonium, as well as in the intensity of infestation and the proportion of infested fruits by T. soror. The concentration of scopolamine in seeds and leaves are negatively associated across populations. We found that scopolamine concentration increases plant fitness. Our major finding was the detection of a positive relationship between the population average concentrations of scopolamine with the selection differentials of scopolamine. Such spatial variation in the direction and intensity of selection on scopolamine may represent a coevolutionary selective mosaic. Our results support the view that variation in the concentration of scopolamine among-populations of D. stramonium in central Mexico is being driven, in part, by selection exerted by T. soror, pointing an adaptive role of tropane alkaloids in this plant species. PMID:27114866

  11. Darwin's explanation of design: from natural theology to natural selection.

    PubMed

    Ayala, Francisco J

    2010-08-01

    Copernicus, Galileo, Newton and other physical scientists ushered in a conception of the universe as matter in motion governed by natural laws. Their discoveries brought about a fundamental revolution, namely a commitment to the postulate that the universe obeys immanent laws that can account for natural phenomena. The workings of the universe were brought into the realm of science: explanation through natural laws. Darwin completed the Copernican revolution by extending it to the living world. Darwin demonstrated the evolution of organisms. More important yet is that he discovered natural selection, the process that explains the "design" of organisms. The adaptations and diversity of organisms, the origin of novel and complex species, even the origin of mankind, could now be explained by an orderly process of change governed by natural laws. The origin of species and the exquisite features of organisms had previously been explained as special creations of an Omniscient God. Darwin brought them into the domain of science. Evolution is a creative process that produces genuine novelty. The creative power of evolution arises from a distinctive interaction between chance and necessity, between random mutation and natural selection. PMID:19800418

  12. A Lesson on Evolution & Natural Selection

    ERIC Educational Resources Information Center

    Curtis, Anthony D.

    2010-01-01

    I describe three activities that allow students to explore the ideas of evolution, natural selection, extinction, mass extinction, and rates of evolutionary change by engaging a simple model using paper, pens, chalk, and a chalkboard. As a culminating activity that supports expository writing in the sciences, the students write an essay on mass…

  13. Antimycobacterial agents from selected Mexican medicinal plants.

    PubMed

    Rivero-Cruz, Isabel; Acevedo, Laura; Guerrero, José A; Martínez, Sergio; Bye, Robert; Pereda-Miranda, Rogelio; Franzblau, Scott; Timmermann, Barbara N; Mata, Rachel

    2005-09-01

    As part of the ICBG program Bioactive Agents from Dryland Biodiversity of Latin America, the present investigation was undertaken to explore the possible antimycobacterial potential of compounds derived from selected Mexican medicinal plants. Bioassay-guided fractionation of the crude extracts of Rumex hymenosepalus (Polygonaceae), Larrea divaricata (Zygophyllaceae), Phoradendron robinsonii (Loranthaceae) and Amphipteryngium adstringens (Julianiaceae) led to the isolation of several antimycobacterial compounds. Four stilbenoids, two flavan-3-ols and three anthraquinones were isolated from R. hymenosepalus. Two flavonols and nordihydroguaiaretic acid were obtained from L. divaricata. Sakuranetin was the antimycobacterial agent isolated from P. robinsonii. Two known triterpenoids and the novel natural product 3-dodecyl-1,8-dihydroxy-2-naphthoic acid were obtained from A. adstringens. In general, the isolates were identified by spectral means. The antimycobacterial activity of the secondary compounds isolated from the analysed species, as well as that of nine pure compounds previously isolated in our laboratories, was investigated; the MIC values ranged from 16 to 128 microg mL-1. Among the tested compounds, the glycolipids, sesquiterpenoids and triterpenoids showed the best antimycobacterial activity. The antimycobacterial property of the glycolipids is reported for the first time. Although the tested compounds showed moderate antimycobacterial activity, their presence in the analysed species provides the rationale for their traditional use in the treatment of tuberculosis. PMID:16105233

  14. Missing concepts in natural selection theory reconstructions.

    PubMed

    Ginnobili, Santiago

    2016-09-01

    The concept of fitness has generated a lot of discussion in philosophy of biology. There is, however, relative agreement about the need to distinguish at least two uses of the term: ecological fitness on the one hand, and population genetics fitness on the other. The goal of this paper is to give an explication of the concept of ecological fitness by providing a reconstruction of the theory of natural selection in which this concept was framed, that is, based on the way the theory was put to use in Darwin's main texts. I will contend that this reconstruction enables us to account for the current use of the theory of natural selection. The framework presupposed in the analysis will be that of metatheoretical structuralism. This framework will provide both a better understanding of the nature of ecological fitness and a more complete reconstruction of the theory. In particular, it will provide what I think is a better way of understanding how the concept of fitness is applied through heterogeneous cases. One of the major advantages of my way of thinking about natural selection theory is that it would not have the peculiar metatheoretical status that it has in other available views. I will argue that in order to achieve these goals it is necessary to make several concepts explicit, concepts that are frequently omitted in usual reconstructions. PMID:27385113

  15. Viability selection prior to trait expression is an essential component of natural selection

    PubMed Central

    Mojica, Julius P.; Kelly, John K.

    2010-01-01

    Natural selection operates throughout the life cycle of an organism. Correlative studies typically fail to consider the effects of viability selection prior to trait expression. A 3-year field experiment on the wildflower Mimulus guttatus demonstrates that this unmeasured component of selection can be very strong. As in previous studies, we find that fecundity is positively related to flower size. However, survival to flowering is much lower in large-flowered genotypes than in small-flowered genotypes. Aggregating viability and fecundity, lifetime fitness through female function generally favoured smaller flowered genotypes. This result differs from the great majority of field studies, which suggest strong positive selection on flower size. It has important cautionary implications for studies of natural and sexual selection on adult characters generally, in both plants and animals. PMID:20462906

  16. The naturalization of the oil collecting bee Centris nitida (Hymenoptera, Apidae, Centrini), a potential pollinator of selected native, ornamental and invasive plants in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The neotropical bee Centris nitida, recorded also from southern Arizona, has naturalized in southeastern Florida. This furry yellow and black bee has been confused with the similar C. lanosa, a native bee restricted to northern Florida and the Southwest and adjacent Mexico. Female C. nitida are smal...

  17. Natural Paradigms of Plant Cell Wall Degradation

    SciTech Connect

    Wei, H.; Xu, Q.; Taylor, L. E.; Baker, J. O.; Tucker, M. P.; Ding, S. Y.

    2009-01-01

    Natural processes of recycling carbon from plant cell walls are slow but very efficient, generally involving microbial communities and their secreted enzymes. Efficient combinations of microbial communities and enzymes act in a sequential and synergistic manner to degrade plant cell walls. Recent understanding of plant cell wall ultra-structure, as well as the carbon metabolism, ATP production, and ecology of participating microbial communities, and the biochemical properties of their cellulolytic enzymes have led to new perspectives on saccharification of biomass. Microbial communities are dynamic functions of the chemical and structural compositions of plant cell wall components. The primitive 'multicellularity' exhibited by certain cellulolytic microorganisms may play a role in facilitating cell-cell communication and cell-plant cell wall-substrate interaction.

  18. Darwinian natural selection: its enduring explanatory power

    PubMed Central

    2012-01-01

    Evolutionary theory has never had a stronger scientific foundation than it does today. In a short review I hope to portray the deep commitment of today's biologists to Darwinian natural selection and to discoveries made since Darwin's time. In spite of the scientific advances in the century and a half since the publication of On the Origin of Species, Darwin still remains the principal author of modern evolutionary theory. He is one of the greatest contributors of all time to our understanding of nature. PMID:22481845

  19. Darwinian natural selection: its enduring explanatory power.

    PubMed

    Dimijian, Gregory G

    2012-04-01

    Evolutionary theory has never had a stronger scientific foundation than it does today. In a short review I hope to portray the deep commitment of today's biologists to Darwinian natural selection and to discoveries made since Darwin's time. In spite of the scientific advances in the century and a half since the publication of On the Origin of Species, Darwin still remains the principal author of modern evolutionary theory. He is one of the greatest contributors of all time to our understanding of nature. PMID:22481845

  20. A Systematic Approach to Discover and Characterize Natural Plant Biostimulants

    PubMed Central

    Povero, Giovanni; Mejia, Juan F.; Di Tommaso, Donata; Piaggesi, Alberto; Warrior, Prem

    2016-01-01

    The use of natural plant biostimulants is proposed as an innovative solution to address the challenges to sustainable agriculture, to ensure optimal nutrient uptake, crop yield, quality, and tolerance to abiotic stress. However, the process of selection and characterization of plant biostimulant matrices is complex and involves a series of rigorous evaluations customized to the needs of the plant. Here, we propose a highly differentiated plant biostimulant development and production platform, which involves a combination of technology, processes, and know-how. Chemistry, biology and omic concepts are combined/integrated to investigate and understand the specific mode(s) of action of bioactive ingredients. The proposed approach allows to predict and characterize the function of natural compounds as biostimulants. By managing and analyzing massive amounts of complex data, it is therefore possible to discover, evaluate and validate new product candidates, thus expanding the uses of existing products to meet the emerging needs of agriculture. PMID:27092156

  1. Naturally Occurring Fish Poisons from Plants

    ERIC Educational Resources Information Center

    Cannon, Jonathan G.; Burton, Robert A.; Wood, Steven G.; Owen, Noel L.

    2004-01-01

    The fish poisons derived from plants used throughout the world, not only as piscicides but also for a range of other uses, including insecticident and in folk medicines, is presented. The aim of this review is to provide a useful background for students interested in natural products.

  2. Mechanistic Advances in Plant Natural Product Enzymes

    PubMed Central

    Usera, Aimee R.; O’Connor, Sarah E.

    2009-01-01

    Summary of Recent Advances The biosynthetic pathways of plant natural products offer an abundance of knowledge to scientists in many fields. Synthetic chemists can be inspired by the synthetic strategies that nature uses to construct these compounds. Chemical and biological engineers are working to reprogram these biosynthetic pathways to more efficiently produce valuable products. Finally, biochemists and enzymologists are interested in the detailed mechanisms of the complex transformations involved in construction of these natural products. Study of biosynthetic enzymes and pathways therefore has a wide-ranging impact. In recent years, many plant biosynthetic pathways have been characterized, particularly the pathways that are responsible for alkaloid biosynthesis. Here we highlight recently studied alkaloid biosynthetic enzymes that catalyze production of numerous complex medicinal compounds, as well as the specifier proteins in glucosinosolate biosynthesis, whose structure and mechanism of action are just beginning to be unraveled. PMID:19632140

  3. Optimize control of natural gas plants

    SciTech Connect

    Treiber, S.; Walker, J.; Tremblay, M. de ); Delgadillo, R.L.; Velasquez, R.N.; Valarde, M.J.G. )

    1994-04-01

    Multivariable constraint control (MCS) has a very beneficial and profitable impact on the operation of natural gas plants. The applications described operate completely within a distributed control system (DCS) or programmable logic controllers (PLCs). That makes MCS accessible to almost all gas plant operators. The technology's relative ease of use, low maintenance effort and software sensor,'' make it possible to operate these control applications without increasing technical support staff. MCS improves not only profitability but also regulatory compliance of gas plants. It has been applied to fractionation units, cryogenic units, amine treaters, sulfur recovery units and utilities. The application typically pay for the cost of software and engineering in less than one month. If a DCS is installed within such a project the advanced control applications can generate a payout in less than one year. In the case here (an application on the deethanizers of a 500 MMscfd gas plant) product revenue increased by over $2 million/yr.

  4. Analysing nature's experiment: Fisher's inductive theorem of natural selection.

    PubMed

    Edwards, A W F

    2016-06-01

    The paper by Ewens and Lessard (2015) adds to the progress that has been made in exploring the discrete-generation analytical version of Fisher's Fundamental Theorem of Natural Selection introduced by Ewens (1989). Fisher's continuous-time theorem differs from the version described by Ewens and Lessard by using a different concept of fitness. Ewens and Lessard use the conventional 'viability' concept whereas for Fisher the fitness of a genotype was its relative rate of increase or decrease in the population. The sole purpose of the present paper is to emphasize the alternative inductive nature of Fisher's theorem, as presented by him in 1930, by placing it in the context of his contemporary development of the analysis of variance in agricultural experiments. It is not a general discussion of the theorem itself. PMID:26581894

  5. Plant cell culture strategies for the production of natural products

    PubMed Central

    Ochoa-Villarreal, Marisol; Howat, Susan; Hong, SunMi; Jang, Mi Ok; Jin, Young-Woo; Lee, Eun-Kyong; Loake, Gary J.

    2016-01-01

    Plants have evolved a vast chemical cornucopia to support their sessile lifestyles. Man has exploited this natural resource since Neolithic times and currently plant-derived chemicals are exploited for a myriad of applications. However, plant sources of most high-value natural products (NPs) are not domesticated and therefore their production cannot be undertaken on an agricultural scale. Further, these plant species are often slow growing, their populations limiting, the concentration of the target molecule highly variable and routinely present at extremely low concentrations. Plant cell and organ culture constitutes a sustainable, controllable and environmentally friendly tool for the industrial production of plant NPs. Further, advances in cell line selection, biotransformation, product secretion, cell permeabilisation, extraction and scale-up, among others, are driving increases in plant NP yields. However, there remain significant obstacles to the commercial synthesis of high-value chemicals from these sources. The relatively recent isolation, culturing and characterisation of cambial meristematic cells (CMCs), provides an emerging platform to circumvent many of these potential difficulties. [BMB Reports 2016; 49(3): 149-158] PMID:26698871

  6. Natural selection and the maximization of fitness.

    PubMed

    Birch, Jonathan

    2016-08-01

    The notion that natural selection is a process of fitness maximization gets a bad press in population genetics, yet in other areas of biology the view that organisms behave as if attempting to maximize their fitness remains widespread. Here I critically appraise the prospects for reconciliation. I first distinguish four varieties of fitness maximization. I then examine two recent developments that may appear to vindicate at least one of these varieties. The first is the 'new' interpretation of Fisher's fundamental theorem of natural selection, on which the theorem is exactly true for any evolving population that satisfies some minimal assumptions. The second is the Formal Darwinism project, which forges links between gene frequency change and optimal strategy choice. In both cases, I argue that the results fail to establish a biologically significant maximization principle. I conclude that it may be a mistake to look for universal maximization principles justified by theory alone. A more promising approach may be to find maximization principles that apply conditionally and to show that the conditions were satisfied in the evolution of particular traits. PMID:25899152

  7. The natural selection of altruistic traits.

    PubMed

    Boehm, C

    1999-09-01

    Proponents of the standard evolutionary biology paradigm explain human "altruism" in terms of either nepotism or strict reciprocity. On that basis our underlying nature is reduced to a function of inclusive fitness: human nature has to be totally selfish or nepotistic. Proposed here are three possible paths to giving costly aid to nonrelatives, paths that are controversial because they involve assumed pleiotropic effects or group selection. One path is pleiotropic subsidies that help to extend nepotistic helping behavior from close family to nonrelatives. Another is "warfare"-if and only if warfare recurred in the Paleolithic. The third and most plausible hypothesis is based on the morally based egalitarian syndrome of prehistoric hunter-gatherers, which reduced phenotypic variation at the within-group level, increased it at the between-group level, and drastically curtailed the advantages of free riders. In an analysis consistent with the fundamental tenets of evolutionary biology, these three paths are evaluated as explanations for the evolutionary development of a rather complicated human social nature. PMID:26196335

  8. Phenotypic selection favors missing trait combinations in coexisting annual plants.

    PubMed

    Kimball, Sarah; Gremer, Jennifer R; Huxman, Travis E; Lawrence Venable, D; Angert, Amy L

    2013-08-01

    Trade-offs among traits are important for maintaining biodiversity, but the role of natural selection in their construction is not often known. It is possible that trade-offs reflect fundamental constraints, negative correlational selection, or directional selection operating on costly, redundant traits. In a Sonoran Desert community of winter annual plants, we have identified a trade-off between relative growth rate and water-use efficiency among species, such that species with high relative growth rate have low water-use efficiency and vice versa. We measured selection on water-use efficiency, relative growth rate, and underlying traits within populations of four species at two study sites with different average climates. Phenotypic trait correlations within species did not match the among-species trade-off. In fact, for two species with high water-use efficiency, individuals with high relative growth rate also had high water-use efficiency. All populations experienced positive directional selection for water-use efficiency and relative growth rate. Selection tended to be stronger on water-use efficiency at the warmer and drier site, and selection on relative growth rate tended to be stronger at the cooler and wetter site. Our results indicate that directional natural selection favors a phenotype not observed among species in the community, suggesting that the among-species trade-off could be due to pervasive genetic constraints, perhaps acting in concert with processes of community assembly. PMID:23852354

  9. Proof of the Wave Nature of Plants

    NASA Astrophysics Data System (ADS)

    Wagner, Orvin

    2008-03-01

    I assume plants operate with a set of frequencies. These frequencies and the means of these frequencies are equal in all directions. We can then write (vh/λ)avh=(vv/λ)avv where the subscripts h and v represent horizontal and vertical respectively and av is average,. or vv/vh=(1/λh)av/(1/λv)av. I use an internodal spacing as λ/2 or the the distance between adjacent branches, leaves, etc. The ratios, vv/vh, are ratios of small integers for sufficient samplings. For example, for Ponderosa pine the ratio is 3/1 or for delicious apple 4/3. Note that these ratios represent the shape of the tree or other plant and their interactions with gravity. These ratios are derivable by other means such as use the ratio of # of horizontal needles per unit length from a horizontal sample to the # of needles per unit length from a vertical sample from p-pine. Or measure the vertical and horizontal velocities. My literature provides many other proofs of the wave nature of plants. I suggest that the waves in and related waves outside of plants (outside 4.9 m/s) are a dark matter related since they travel at such low velocities. See my present web site at home.budget.net/˜oedphd.

  10. The incidental response to uniform natural selection

    PubMed Central

    Bell, Graham

    2013-01-01

    When populations are exposed to novel conditions of growth, they often become adapted to a similar extent, and at the same time, evolve some degree of impairment in their original environment. They may also come to vary widely with respect to characters which are uncorrelated with fitness, as the result of chance genetic associations among the founders, when these are a small sample from a large and variable ancestral population. I report an experiment in which 240 replicate lines of the unicellular chlorophyte Chlamydomonas were derived from primarily photoautotrophic ancestors and cultured as heterotrophs in the dark. All adapted to the dark and were impaired in the light after several hundred generations of culture. They also displayed a wide range of colony morphologies that were uncorrelated with fitness. This incidental response to selection probably arose through random variation in the initial composition of the lines. The differences between closely related species or varieties may likewise arise, in similar circumstances, by sampling error rather than natural selection. PMID:23697640

  11. Plant biochemistry: a naturally decaffeinated arabica coffee.

    PubMed

    Silvarolla, Maria B; Mazzafera, Paulo; Fazuoli, Luiz C

    2004-06-24

    The adverse side effects of caffeine have increased the market for decaffeinated coffee to about 10% of coffee consumption worldwide (http://www.ncausa.org), despite the loss of key flavour compounds in the industrial decaffeinating process. We have discovered a naturally decaffeinated Coffea arabica plant from Ethiopia, a species normally recognized for the high quality of its beans. It should be possible to transfer this trait to commercial varieties of arabica coffee plants by intraspecific hybridization--a process likely to be simpler than an interspecific hybridization strategy, which could require more than 30 years of breeding to fix the decaffeinated trait and would probably result in an inferior cup of coffee. PMID:15215853

  12. Using Card Games to Simulate the Process of Natural Selection

    ERIC Educational Resources Information Center

    Grilliot, Matthew E.; Harden, Siegfried

    2014-01-01

    In 1858, Darwin published "On the Origin of Species by Means of Natural Selection." His explanation of evolution by natural selection has become the unifying theme of biology. We have found that many students do not fully comprehend the process of evolution by natural selection. We discuss a few simple games that incorporate hands-on…

  13. Bridging Emergent Attributes and Darwinian Principles in Teaching Natural Selection

    ERIC Educational Resources Information Center

    Xu, Dongchen; Chi, Michelene T. H.

    2016-01-01

    Students often have misconceptions about natural selection as they misuse a direct causal schema to explain the process. Natural selection is in fact an emergent process where random interactions lead to changes in a population. The misconceptions stem from students' lack of emergent schema for natural selection. In order to help students…

  14. Natural selection and the elusiveness of happiness.

    PubMed Central

    Nesse, Randolph M

    2004-01-01

    The quest for happiness has expanded from a focus on relieving suffering to also considering how to promote happiness. However, both approaches have yet to be conducted in an evolutionary framework based on the situations that shaped the capacities for happiness and sadness. Because of this, the emphasis has almost all been on the disadvantages of negative states and the benefits of positive states, to the nearly total neglect of 'diagonal psychology', which also considers the dangers of unwarranted positive states and the benefits of negative emotions in certain situations. The situations that arise in goal pursuit contain adaptive challenges that have shaped domain-general positive and negative emotions that were partially differentiated by natural selection to cope with the more specific situations that arise in the pursuit of different kinds of goals. In cultures where large social groups give rise to specialized and competitive social roles, depression may be common because regulation systems are pushed far beyond the bounds for which they were designed. Research on the evolutionary origins of the capacities for positive and negative emotions is urgently needed to provide a foundation for sensible decisions about the use of new mood-manipulating technologies. PMID:15347525

  15. Darwinian agriculture: when can humans find solutions beyond the reach of natural selection?

    PubMed

    Denison, R Ford; Kiers, E Toby; West, Stuart A

    2003-06-01

    Progress in genetic improvement of crop yield potential has slowed since 1985. Simultaneously, more sustainable management of agricultural ecosystems is needed. A better understanding of natural selection can help solve both problems. We illustrate this point with two specific examples. First, the genetic legacy of crop plants has been refined by millions of years of natural selection, often driven by competition among plants. We therefore suggest that most simple, tradeoff-free options to increase competitiveness (e.g., increased gene expression, or minor modifications of existing plant genes) have already been tested by natural selection. Further genetic improvement of crop yield potential over the next decade will mainly involve tradeoffs, either between fitness in past versus present environments, or between individual competitiveness and the collective performance of plant communities. Eventually, we may develop the ability to predict the consequences of genetic alterations so radical that they have not yet been tested by natural selection. Second, natural selection acts mainly at the level of genes, individuals, and family groups, rather than ecosystems as a whole. Consequently, there is no reason to expect the structure of natural ecosystems (diversity, spatial, or temporal patterns) to be a reliable blueprint for agricultural ecosystems. Natural ecosystems are nonetheless an important source of information that could be used to improve agriculture. PMID:12825416

  16. Cytotoxic activity of selected Nigerian plants.

    PubMed

    Sowemimo, A; van de Venter, M; Baatjies, L; Koekemoer, T

    2009-01-01

    Cancer is one of the most prominent human diseases which has stimulated scientific and commercial interest in the discovery of new anticancer agents from natural sources. The current study investigates the cytotoxic activity of ethanolic extracts of sixteen Nigerian plants used locally for the treatment of cancer using the MTT assay on the HeLa cell line. Sapium ellipticum leaves showed activity comparable to the reference compound Cisplatin and greater cytotoxic activity than Combretum paniculatum, Celosia trigyna, Drymaria cordata, Cyathula achyranthoides and Cyathula prostata. Justica extensa, Pupalia lappacea, Hedranthera barteri leaves, Alternanthera sessilis, Ethulia conyzoides leaves, Combretum zenkeri root, Sapium ellipticum stembark and Lannea nigritana stembark showed very low activity while Combretum molle, Adenanthera parvoniana and Lannea acida showed no activity. The results justify the use of Sapium, Combretum, Celosia, Drymaria and Cyathula in traditional treatment of cancer. PMID:20606772

  17. A model for plant lighting system selection

    NASA Technical Reports Server (NTRS)

    Ciolkosz, D. E.; Albright, L. D.; Sager, J. C.; Langhans, R. W.

    2002-01-01

    A decision model is presented that compares lighting systems for a plant growth scenario and chooses the most appropriate system from a given set of possible choices. The model utilizes a Multiple Attribute Utility Theory approach, and incorporates expert input and performance simulations to calculate a utility value for each lighting system being considered. The system with the highest utility is deemed the most appropriate system. The model was applied to a greenhouse scenario, and analyses were conducted to test the model's output for validity. Parameter variation indicates that the model performed as expected. Analysis of model output indicates that differences in utility among the candidate lighting systems were sufficiently large to give confidence that the model's order of selection was valid.

  18. Microbial Resistance to Triclosan: A Case Study in Natural Selection

    ERIC Educational Resources Information Center

    Serafini, Amanda; Matthews, Dorothy M.

    2009-01-01

    Natural selection is the mechanism of evolution caused by the environmental selection of organisms most fit to reproduce, sometimes explained as "survival of the fittest." An example of evolution by natural selection is the development of bacteria that are resistant to antimicrobial agents as a result of exposure to these agents. Triclosan, which…

  19. Natural selection stops the evolution of male attractiveness.

    PubMed

    Hine, Emma; McGuigan, Katrina; Blows, Mark W

    2011-03-01

    Sexual selection in natural populations acts on highly heritable traits and tends to be relatively strong, implicating sexual selection as a causal agent in many phenotypic radiations. Sexual selection appears to be ineffectual in promoting phenotypic divergence among contemporary natural populations, however, and there is little evidence from artificial selection experiments that sexual fitness can evolve. Here, we demonstrate that a multivariate male trait preferred by Drosophila serrata females can respond to selection and results in the maintenance of male mating success. The response to selection was associated with a gene of major effect increasing in frequency from 12 to 35% in seven generations. No further response to selection, or increase in frequency of the major gene, was observed between generations 7 and 11, indicating an evolutionary limit had been reached. Genetic analyses excluded both depletion of genetic variation and overdominance as causes of the evolutionary limit. Relaxing artificial selection resulted in the loss of 52% of the selection response after a further five generations, demonstrating that the response under artificial sexual selection was opposed by antagonistic natural selection. We conclude that male D. serrata sexually selected traits, and attractiveness to D. serrata females conferred by these traits, were held at an evolutionary limit by the lack of genetic variation that would allow an increase in sexual fitness while simultaneously maintaining nonsexual fitness. Our results suggest that sexual selection is unlikely to cause divergence among natural populations without a concomitant change in natural selection, a conclusion consistent with observational evidence from natural populations. PMID:21321197

  20. Lessons from natural and artificial polyploids in higher plants.

    PubMed

    Hegarty, M; Coate, J; Sherman-Broyles, S; Abbott, R; Hiscock, S; Doyle, J

    2013-01-01

    Polyploidy in higher plants is a major source of genetic novelty upon which selection may act to drive evolution, as evidenced by the widespread success of polyploid species in the wild. However, research into the effects of polyploidy can be confounded by the entanglement of several processes: genome duplication, hybridisation (allopolyploidy is frequent in plants) and subsequent evolution. The discovery of the chemical agent colchicine, which can be used to produce artificial polyploids on demand, has enabled scientists to unravel these threads and understand the complex genomic changes involved in each. We present here an overview of lessons learnt from studies of natural and artificial polyploids, and from comparisons between the 2, covering basic cellular and metabolic consequences through to alterations in epigenetic gene regulation, together with 2 in-depth case studies in Senecio and Glycine. See also the sister article focusing on animals by Arai and Fujimoto in this themed issue. PMID:23816545

  1. ENHANCEMENTS TO NATURAL ATTENUATION: SELECTED CASE STUDIES

    SciTech Connect

    Vangelas, K; W. H. Albright, W; E. S. Becvar, E; C. H. Benson, C; T. O. Early, T; E. Hood, E; P. M. Jardine, P; M. Lorah, M; E. Majche, E; D. Major, D; W. J. Waugh, W; G. Wein, G; O. R. West, O

    2007-05-15

    In 2003 the US Department of Energy (DOE) embarked on a project to explore an innovative approach to remediation of subsurface contaminant plumes that focused on introducing mechanisms for augmenting natural attenuation to achieve site closure. Termed enhanced attenuation (EA), this approach has drawn its inspiration from the concept of monitored natural attenuation (MNA).

  2. Natural Selection, Nutrition Research, and Science Teaching.

    ERIC Educational Resources Information Center

    Nelson, Darby

    1980-01-01

    Provides examples of the teaching of hypothesis generation and scientific inquiry in biology. Specifically, the author applies the selection paradigm to considerations of the human nutrient-handling apparatus, finally suggesting a model of the selective forces that may have operated on the human genome since hunting-gathering and primitive…

  3. Herbivores can select for mixed defensive strategies in plants.

    PubMed

    Carmona, Diego; Fornoni, Juan

    2013-01-01

    Resistance and tolerance are the most important defense mechanisms against herbivores. Initial theoretical studies considered both mechanisms functionally redundant, but more recent empirical studies suggest that these mechanisms may complement each other, favoring the presence of mixed defense patterns. However, the expectation of redundancy between tolerance and resistance remains unsupported. In this study, we tested this assumption following an ecological genetics field experiment in which the presence/absence of two herbivores (Lema daturaphila and Epitrix parvula) of Datura stramonium were manipulated. In each of three treatments, genotypic selection analyses were performed and selection patterns compared. Our results indicated that selection on resistance and tolerance was significantly different between the two folivores. Tolerance and resistance are not redundant defense strategies in D. stramonium but instead functioned as complementary defenses against both beetle species, favoring the evolution of a mixed defense strategy. Although each herbivore was selected for different defense strategies, the observed average tolerance and resistance were closer to the adaptive peak predicted against E. parvula and both beetles together. In our experimental population, natural selection imposed by herbivores can favor the evolution of mixed defense strategies in plants, accounting for the presence of intermediate levels of tolerance and resistance. PMID:23171270

  4. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    ERIC Educational Resources Information Center

    Thagard, Paul; Findlay, Scott

    2010-01-01

    Darwin's theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin's theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that…

  5. Natural Selection in the Field and the Classroom

    ERIC Educational Resources Information Center

    Andrews, Tessa Marie

    2012-01-01

    This dissertation examined natural selection in westslope cutthroat trout ("Oncorhynchus clarkii lewisi") and undergraduate learning in the subject area natural selection. Translocation--moving individuals to a new habitat to establish, re-establish or supplement a population--is a crucial management strategy for cutthroat trout. One of…

  6. Are Humans Still Evolving? A Natural Selection Discussion Lesson

    ERIC Educational Resources Information Center

    Shields, Martin

    2004-01-01

    A study is conducted to develop sound comprehension of natural selection theory by prompting students to use its concept to explain the evolutionary status of humans. In relation to the current existence of human it is stated that human populations currently undergo microevolutionary changes in allele frequencies due to natural selection and other…

  7. A Working Model of Natural Selection Illustrated by Table Tennis

    ERIC Educational Resources Information Center

    Dinc, Muhittin; Kilic, Selda; Aladag, Caner

    2013-01-01

    Natural selection is one of the most important topics in biology and it helps to clarify the variety and complexity of organisms. However, students in almost every stage of education find it difficult to understand the mechanism of natural selection and they can develop misconceptions about it. This article provides an active model of natural…

  8. Development and Evaluation of the Conceptual Inventory of Natural Selection.

    ERIC Educational Resources Information Center

    Anderson, Dianne L.; Fisher, Kathleen M.; Norman, Gregory J.

    2002-01-01

    Presents a diagnostic test to assess students' understanding of natural selection. Field-tests the Conceptual Inventory of Natural Selection (CINS) with nonmajors and biology majors at community colleges. Compares test scores of nonmajors with performances in interviews and discusses the correlation between the test scores and the interview…

  9. Biosynthesis of natural products in plants by fungal endophytes with an emphasis on swainsonine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant natural products are frequently used as chemotaxonomic markers which are indicative of select members of a family, genus, and/or species. However, the erratic occurrence of some natural products raises questions about their biosynthetic origin and significance as chemotaxonomic markers. Rece...

  10. Linkage and the Limits to Natural Selection

    PubMed Central

    Barton, N. H.

    1995-01-01

    The probability of fixation of a favorable mutation is reduced if selection at other loci causes inherited variation in fitness. A general method for calculating the fixation probability of an allele that can find itself in a variety of genetic backgrounds is applied to find the effect of substitutions, fluctuating polymorphisms, and deleterious mutations in a large population. With loose linkage, r, the effects depend on the additive genetic variance in relative fitness, var (W), and act by reducing effective population size by (N/N(e)) = 1 + var (W)/2r(2). However, tightly linked loci can have a substantial effect not predictable from N(e). Linked deleterious mutations reduce the fixation probability of weakly favored alleles by exp(-2U/R), where U is the total mutation rate and R is the map length in Morgans. Substitutions can cause a greater reduction: an allele with advantage s < s(crit) = (π(2)/6) log(e) (S/s)[var(W)/R] is very unlikely to be fixed. (S is the advantage of the substitution impeding fixation.) Fluctuating polymorphisms at many (n) linked loci can also have a substantial effect, reducing fixation probability by exp [ &2Kn var(W)/R] [K = -1/E((u - u)(2)/uv) depending on the frequencies (u,v) at the selected polymorphisms]. Hitchhiking due to all three kinds of selection may substantially impede adaptation that depends on weakly favored alleles. PMID:7498757

  11. Canine evolution in sabretoothed carnivores: natural selection or sexual selection?

    PubMed

    Randau, Marcela; Carbone, Chris; Turvey, Samuel T

    2013-01-01

    The remarkable elongated upper canines of extinct sabretoothed carnivorous mammals have been the subject of considerable speculation on their adaptive function, but the absence of living analogues prevents any direct inference about their evolution. We analysed scaling relationships of the upper canines of 20 sabretoothed feliform carnivores (Nimravidae, Barbourofelidae, Machairodontinae), representing both dirk-toothed and scimitar-toothed sabretooth ecomorphs, and 33 non-sabretoothed felids in relation to body size in order to characterize and identify the evolutionary processes driving their development, using the scaling relationships of carnassial teeth in both groups as a control. Carnassials display isometric allometry in both sabretooths and non-sabretooths, supporting their close relationship with meat-slicing, whereas the upper canines of both groups display positive allometry with body size. Whereas there is no statistical difference in allometry of upper canine height between dirk-toothed and scimitar-toothed sabretooth ecomorphs, the significantly stronger positive allometry of upper canine height shown by sabretooths as a whole compared to non-sabretooths reveals that different processes drove canine evolution in these groups. Although sabretoothed canines must still have been effective for prey capture and processing by hypercarnivorous predators, canine morphology in these extinct carnivores was likely to have been driven to a greater extent by sexual selection than in non-sabretooths. Scaling relationships therefore indicate the probable importance of sexual selection in the evolution of the hypertrophied sabretooth anterior dentition. PMID:23951334

  12. Plant phosphomannose isomerase as a selectable marker for rice transformation

    PubMed Central

    Hu, Lei; Li, Hao; Qin, Ruiying; Xu, Rongfang; Li, Juan; Li, Li; Wei, Pengcheng; Yang, Jianbo

    2016-01-01

    The E. coli phosphomannose isomerase (EcPMI) gene is widely used as a selectable marker gene (SMG) in mannose (Man) selection-based plant transformation. Although some plant species exhibit significant PMI activity and active PMIs were even identified in Man-sensitive plants, whether plant PMIs can be used as SMGs remains unclear. In this study, we isolated four novel PMI genes from Chlorella variabilis and Oryza sativa. Their isoenzymatic activities were examined in vitro and compared with that of EcPMI. The active plant PMIs were separately constructed into binary vectors as SMGs and then transformed into rice via Agrobacterium. In both Indica and Japonica subspecies, our results indicated that the plant PMIs could select and produce transgenic plants in a pattern similar to that of EcPMI. The transgenic plants exhibited an accumulation of plant PMI transcripts and enhancement of the in vivo PMI activity. Furthermore, a gene of interest was successfully transformed into rice using the plant PMIs as SMGs. Thus, novel SMGs for Man selection were isolated from plants, and our analysis suggested that PMIs encoding active enzymes might be common in plants and could potentially be used as appropriate genetic elements in cisgenesis engineering. PMID:27174847

  13. Plant phosphomannose isomerase as a selectable marker for rice transformation.

    PubMed

    Hu, Lei; Li, Hao; Qin, Ruiying; Xu, Rongfang; Li, Juan; Li, Li; Wei, Pengcheng; Yang, Jianbo

    2016-01-01

    The E. coli phosphomannose isomerase (EcPMI) gene is widely used as a selectable marker gene (SMG) in mannose (Man) selection-based plant transformation. Although some plant species exhibit significant PMI activity and active PMIs were even identified in Man-sensitive plants, whether plant PMIs can be used as SMGs remains unclear. In this study, we isolated four novel PMI genes from Chlorella variabilis and Oryza sativa. Their isoenzymatic activities were examined in vitro and compared with that of EcPMI. The active plant PMIs were separately constructed into binary vectors as SMGs and then transformed into rice via Agrobacterium. In both Indica and Japonica subspecies, our results indicated that the plant PMIs could select and produce transgenic plants in a pattern similar to that of EcPMI. The transgenic plants exhibited an accumulation of plant PMI transcripts and enhancement of the in vivo PMI activity. Furthermore, a gene of interest was successfully transformed into rice using the plant PMIs as SMGs. Thus, novel SMGs for Man selection were isolated from plants, and our analysis suggested that PMIs encoding active enzymes might be common in plants and could potentially be used as appropriate genetic elements in cisgenesis engineering. PMID:27174847

  14. Habitat selection by three littoral zone fishes: effects of predation pressure, plant density and macrophyte type

    USGS Publications Warehouse

    Chick, J.H.; McIvor, C.C.

    1997-01-01

    We conducted laboratory experiments which demonstrated that three littoral zone fishes differentially selected among three macrophytes when seeking refuge from predation. In the presence of a predator (a juvenile Micropterus salmoides), mosquitofish (Gambusia holbrooki), sailfin mollies (Poecilia latipinna). and dollar sunfish (Lepomis marginatus) displayed ferential use of four tank areas containing patches of either Hydrilla verticillata, Potamogeton illinoensis, Panicum hemitomon, or no plants. Patterns habitat selection, and the consistency of these patterns among replicates, differed among the three fishes and among three plant-density treatments - natural (each macrophyte presented at its mean field density), equal (all three macrophytes at the same density), and control (no plants). Selection for H. verticillata by mosquitofish was significant for both the equal and natural treatments, and thus was not caused by differences in plant density alone. Sailfin mollies displayed significant selection for H. verticillata only in the natural plant-density treatments. Dollar sunfish showed less consistent habitat selection than either mosquitofish or sailfin mollies. Significant habitat selection was not found in the absence of a predator, and there was no evidence for lection among the tank areas in control treatments. Patterns of habitat selection by the three fishes in our laboratory study corresponded to observed habitat use in Lake Okeechobee.

  15. Natural selection on floral morphology can be influenced by climate

    PubMed Central

    Campbell, Diane R.; Powers, John M.

    2015-01-01

    Climate has the potential to influence evolution, but how it influences the strength or direction of natural selection is largely unknown. We quantified the strength of selection on four floral traits of the subalpine herb Ipomopsis sp. in 10 years that differed in precipitation, causing extreme temporal variation in the date of snowmelt in the Colorado Rocky Mountains. The chosen floral traits were under selection by hummingbird and hawkmoth pollinators, with hawkmoth abundance highly variable across years. Selection for flower length showed environmental sensitivity, with stronger selection in years with later snowmelt, as higher water resources can allow translation of pollination success into fitness based on seed production. Selection on corolla width also varied across years, favouring narrower corolla tubes in two unusual years with hawkmoths, and wider corollas in another late snowmelt year. Our results illustrate how changes in climate could alter natural selection even when the primary selective agent is not directly influenced. PMID:25972465

  16. Natural selection on floral morphology can be influenced by climate.

    PubMed

    Campbell, Diane R; Powers, John M

    2015-06-01

    Climate has the potential to influence evolution, but how it influences the strength or direction of natural selection is largely unknown. We quantified the strength of selection on four floral traits of the subalpine herb Ipomopsis sp. in 10 years that differed in precipitation, causing extreme temporal variation in the date of snowmelt in the Colorado Rocky Mountains. The chosen floral traits were under selection by hummingbird and hawkmoth pollinators, with hawkmoth abundance highly variable across years. Selection for flower length showed environmental sensitivity, with stronger selection in years with later snowmelt, as higher water resources can allow translation of pollination success into fitness based on seed production. Selection on corolla width also varied across years, favouring narrower corolla tubes in two unusual years with hawkmoths, and wider corollas in another late snowmelt year. Our results illustrate how changes in climate could alter natural selection even when the primary selective agent is not directly influenced. PMID:25972465

  17. Natural selective attention: Orienting and emotion

    PubMed Central

    BRADLEY, MARGARET M.

    2013-01-01

    The foundations of orienting and attention are hypothesized to stem from activation of defensive and appetitive motivational systems that evolved to protect and sustain the life of the individual. Motivational activation initiates a cascade of perceptual and motor processes that facilitate the selection of appropriate behavior. Among these are detection of significance, indexed by a late centro-parietal positivity in the event-related potential, enhanced perceptual processing, indexed by a initial cardiac deceleration, and preparation for action, indexed by electrodermal changes. Data exploring the role of stimulus novelty and significance in orienting are presented that indicate different components of the orienting response habituate at different rates. Taken together, it is suggested that orienting is mediated by activation of fundamental motivational systems that have evolved to support survival. PMID:18778317

  18. Selective molecular sequestration with concurrent natural product functionalization and derivatization: from crude natural product extracts to a single natural product derivative in one step.

    PubMed

    Krchňák, Viktor; Zajíček, Jaroslav; Miller, Patricia A; Miller, Marvin J

    2011-12-16

    A resin-bound nitroso compound sequestered a single unexpected component from crude plant seed extracts. Several plants, including Piper nigrum, Eugenia caryophyllata, and Pimenta dioica, were extracted with organic solvent in the presence of a nitroso-containing resin. The nitroso resin selectively sequestered a single compound, β-caryophyllene, via a chemo- and regioselective ene reaction. The ene product was released from the resin, and proper selection of the solid-phase linker and cleavage cocktail allowed concomitant further transformation of the primary ene product to a novel functionalized polycycle. Preliminary studies indicate that the new hydroxylamine-containing natural product derivatives have antibiotic activity. PMID:22059469

  19. Selective Molecular Sequestration with Concurrent Natural Product Functionalization and Derivatization: From Crude Natural Product Extracts to a Single Natural Product Derivative in One Step

    PubMed Central

    Krchňák, Viktor; Zajíček, Jaroslav; Miller, Patricia A.; Miller, Marvin J.

    2011-01-01

    A resin-bound nitroso compound sequestered a single unexpected component from crude plant seed extracts. Several plants, including Piper nigrum, Eugenia caryophyllata, and Pimenta dioica, were extracted with organic solvent in the presence of a nitroso-containing resin. The nitroso resin selectively sequestered a single compound, β-caryophyllene, via a chemo and regioselective ene reaction. The ene product was released from the resin and proper selection of the solid-phase linker and cleavage cocktail allowed concomitant further transformation of the primary ene product to a novel functionalized polycycle. Preliminary studies indicate that the new hydroxylamine-containing natural product derivatives have antibiotic activity. PMID:22059469

  20. Screening antifungal activities of selected medicinal plants.

    PubMed

    Quiroga, E N; Sampietro, A R; Vattuone, M A

    2001-01-01

    Plants synthesise a vast array of secondary metabolites that are gaining importance for their biotechnological applications. The antifungal activity of the ethanolic extracts of ten Argentinean plants used in native medicine is reported. Antifungal assays included radial growth inhibition, disk and well diffusion assays and growth inhibition by broth dilution tests. The chosen test fungi were yeasts, microfungi and wood-rot causing Basidiomycetes. Extracts of Larrea divaricata, Zuccagnia punctata and Larrea cuneifolia displayed remarkable activity in the assays against the majority of the test fungi. In addition to the former plants, Prosopanche americana also inhibited yeast growth. PMID:11137353

  1. Hamilton's forces of natural selection after forty years.

    PubMed

    Rose, Michael R; Rauser, Casandra L; Benford, Gregory; Matos, Margarida; Mueller, Laurence D

    2007-06-01

    In 1966, William D. Hamilton published a landmark paper in evolutionary biology: "The Moulding of Senescence by Natural Selection." It is now apparent that this article is as important as his better-known 1964 articles on kin selection. Not only did the 1966 article explain aging, it also supplied the basic scaling forces for natural selection over the entire life history. Like the Lorentz transformations of relativistic physics, Hamilton's Forces of Natural Selection provide an overarching framework for understanding the power of natural selection at early ages, the existence of aging, the timing of aging, the cessation of aging, and the timing of the cessation of aging. His twin Forces show that natural selection shapes survival and fecundity in different ways, so their evolution can be somewhat distinct. Hamilton's Forces also define the context in which genetic variation is shaped. The Forces of Natural Selection are readily manipulable using experimental evolution, allowing the deceleration or acceleration of aging, and the shifting of the transition ages between development, aging, and late life. For these reasons, evolutionary research on the demographic features of life history should be referred to as "Hamiltonian." PMID:17542838

  2. Antimycobacterial and cytotoxic activity of selected medicinal plant extracts

    PubMed Central

    Nguta, Joseph M.; Appiah-Opong, Regina; Nyarko, Alexander K.; Yeboah-Manu, Dorothy; Addo, Phyllis G.A.; Otchere, Isaac; Kissi-Twum, Abena

    2016-01-01

    Ethnopharmacological relevance Tuberculosis (TB) caused by Mycobacterium tuberculosis remains an ongoing threat to human health. Several medicinal plants are used traditionally to treat tuberculosis in Ghana. The current study was designed to investigate the antimycobacterial activity and cytotoxicity of crude extracts from five selected medicinal plants. Material and methods The microplate alamar blue assay (MABA) was used for antimycobacterial studies while the CellTiter 96® AQueous Assay, which is composed of solutions of a novel tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] and an electron coupling reagent (phenazine methosulfate) PMS, was used for cytotoxic studies. Correlation coefficients were used to compare the activity of crude extracts against nonpathogenic strains and the pathogenic Mycobacterium tuberculosis subsp.tuberculosis. Results Results of the MIC determinations indicated that all the crude extracts were active on all the three tested mycobacterial strains. Minimum inhibitory concentration values as low as 156.3 µg/mL against M. tuberculosis; Strain H37Ra (ATCC® 25,177™) were recorded from the leaves of Solanum torvum Sw. (Solanaceae). Cytotoxicity of the extracts varied, and the leaves from S. torvum had the most promising selectivity index. Activity against M. tuberculosis; Strain H37Ra was the best predictor of activity against pathogenic Mycobacterium tuberculosis subsp.tuberculosis (correlation coefficient=0.8). Conclusion The overall results of the present study provide supportive data on the use of some medicinal plants for tuberculosis treatment. The leaves of Solanum torvum are a potential source of anti-TB natural products and deserve further investigations to develop novel anti-TB agents against sensitive and drug resistant strains of M. tuberculosis. PMID:26875647

  3. Natural Selection Is a Sorting Process: What Does that Mean?

    ERIC Educational Resources Information Center

    Price, Rebecca M.

    2013-01-01

    To learn why natural selection acts only on existing variation, students categorize processes as either creative or sorting. This activity helps students confront the misconception that adaptations evolve because species need them.

  4. Meta-analysis of phenotypic selection on flowering phenology suggests that early flowering plants are favoured.

    PubMed

    Munguía-Rosas, Miguel A; Ollerton, Jeff; Parra-Tabla, Victor; De-Nova, J Arturo

    2011-05-01

    Flowering times of plants are important life-history components and it has previously been hypothesized that flowering phenologies may be currently subject to natural selection or be selectively neutral. In this study we reviewed the evidence for phenotypic selection acting on flowering phenology using ordinary and phylogenetic meta-analysis. Phenotypic selection exists when a phenotypic trait co-varies with fitness; therefore, we looked for studies reporting an association between two components of flowering phenology (flowering time or flowering synchrony) with fitness. Data sets comprising 87 and 18 plant species were then used to assess the incidence and strength of phenotypic selection on flowering time and flowering synchrony, respectively. The influence of dependence on pollinators, the duration of the reproductive event, latitude and plant longevity as moderators of selection were also explored. Our results suggest that selection favours early flowering plants, but the strength of selection is influenced by latitude, with selection being stronger in temperate environments. However, there is no consistent pattern of selection on flowering synchrony. Our study demonstrates that phenotypic selection on flowering time is consistent and relatively strong, in contrast to previous hypotheses of selective neutrality, and has implications for the evolution of temperate floras under global climate change. PMID:21332621

  5. Naturalization Test Redesign Project: Civics Item Selection Analysis

    ERIC Educational Resources Information Center

    US Citizenship and Immigration Services, 2008

    2008-01-01

    "Naturalization Test Redesign Project: Civics Item Selection Analysis" provides an overview of the development of content items for the U.S. history and government (civics) portion of the redesigned naturalization test. This document also reviews the process used to gather and analyze data from multiple studies to determine which civics test items…

  6. Annotated selected references on natural resources investigations, Collier County, Florida

    USGS Publications Warehouse

    Swayze, L.J.

    1981-01-01

    A data base for future natural resources investigations in Collier County, Fla., was initiated by compiling a selected annotated bibliography. This report provides references and annotations for selected reports released between 1950 and 1978. The references are presented by subject material as follows: biologic, ecologic, geologic, geochemical, and hydrologic. (USGS)

  7. Parts of Plants. Hawaii Nature Study Project.

    ERIC Educational Resources Information Center

    Hawaii Univ., Honolulu. Curriculum Research and Development Group.

    This teaching guide is one of a series developed by the Curriculum Research and Development Group at the University of Hawaii. The program is laboratory and field oriented for elementary students. The focus of study for the project is the plant and animal life and the physical components of the Hawaiian environment, and their ecological…

  8. The genetic consequences of selection in natural populations.

    PubMed

    Thurman, Timothy J; Barrett, Rowan D H

    2016-04-01

    The selection coefficient, s, quantifies the strength of selection acting on a genetic variant. Despite this parameter's central importance to population genetic models, until recently we have known relatively little about the value of s in natural populations. With the development of molecular genetic techniques in the late 20th century and the sequencing technologies that followed, biologists are now able to identify genetic variants and directly relate them to organismal fitness. We reviewed the literature for published estimates of natural selection acting at the genetic level and found over 3000 estimates of selection coefficients from 79 studies. Selection coefficients were roughly exponentially distributed, suggesting that the impact of selection at the genetic level is generally weak but can occasionally be quite strong. We used both nonparametric statistics and formal random-effects meta-analysis to determine how selection varies across biological and methodological categories. Selection was stronger when measured over shorter timescales, with the mean magnitude of s greatest for studies that measured selection within a single generation. Our analyses found conflicting trends when considering how selection varies with the genetic scale (e.g., SNPs or haplotypes) at which it is measured, suggesting a need for further research. Besides these quantitative conclusions, we highlight key issues in the calculation, interpretation, and reporting of selection coefficients and provide recommendations for future research. PMID:26836758

  9. Plant extracts as natural amoebicidal agents.

    PubMed

    Derda, Monika; Hadaś, Edward; Thiem, Barbara

    2009-02-01

    Strains of Acanthamoeba sp. constitute a factor contributing to the occurrence of chronic granulomatous amoebic encephalitis, keratitis, pneumonia, as well as inflammations of other organs. Treatment of these diseases is very difficult and not always effective. A majority of these infections have been fatal. The aim of our study was to examine the amoebicidal or amoebistatic activity of plant extracts from Rubus chamaemorus, Pueraria lobata, Solidago virgaurea and Solidago graminifolia. For the purpose of isolation of pharmacologically active substances, we used the aboveground parts of plants, together with flowers, roots and leaves. It was established that extracts from S. virgauera, P. lobata and R. chamaemorus displayed chemotherapeutic properties in vitro in concentrations of approximately 0.01-0.05 mg extract/mL, i.e., in concentrations of 0.350 microg/mL expressed in ellagic acid for R. chamaemorus and 0.053 microg/mL expressed in puerarin for P. lobata. Therapeutic index values is 3.5-20. As a result of in vivo experiments, it was found out that, following therapy using the extracts, animals infected with Acanthamoeba sp. survived for an extended period (2.5-3 times longer). It was determined that plant extracts may be used both externally and internally in the case of a combined therapy for acanthamoebiasis. The tested extracts are not toxic for animals. PMID:19050923

  10. Facile Synthesis of Natural Alkoxynaphthalene Analogues from Plant Alkoxybenzenes.

    PubMed

    Tsyganov, Dmitry V; Krayushkin, Mikhail M; Konyushkin, Leonid D; Strelenko, Yuri A; Semenova, Marina N; Semenov, Victor V

    2016-04-22

    Analogues of the bioactive natural alkoxynaphthalene pycnanthulignene D were synthesized by an efficient method. The starting plant allylalkoxybenzenes (1) are easily available from the plant essential oils of sassafras, dill, and parsley. The target 1-arylalkoxynaphthalenes (5) exhibited antiproliferative activity in a phenotypic sea urchin embryo assay. PMID:26910798

  11. Using Plants to Explore the Nature & Structural Complexity of Life

    ERIC Educational Resources Information Center

    Howard, Ava R.

    2014-01-01

    Use of real specimens brings the study of biology to life. This activity brings easily acquired plant specimens into the classroom to tackle common alternative conceptions regarding life, size, complexity, the nature of science, and plants as multicellular organisms. The activity occurs after a discussion of the characteristics of life and engages…

  12. Use of space for development of commercial plant natural products

    NASA Astrophysics Data System (ADS)

    Draeger, Norman A.

    1997-01-01

    Plant experiments conducted in environments where conditions are carefully controlled reveal fundamental information about physiological processes. An important environmental parameter is gravity, the effects of which may be better understood in part through experiments conducted in space. New insights gained can be used to develop commercial plant natural products in industries such as pharmaceuticals and biocontrol.

  13. Use of space for development of commercial plant natural products

    SciTech Connect

    Draeger, N.A.

    1997-01-01

    Plant experiments conducted in environments where conditions are carefully controlled reveal fundamental information about physiological processes. An important environmental parameter is gravity, the effects of which may be better understood in part through experiments conducted in space. New insights gained can be used to develop commercial plant natural products in industries such as pharmaceuticals and biocontrol. {copyright} {ital 1997 American Institute of Physics.}

  14. The Limits of Natural Selection in a Nonequilibrium World.

    PubMed

    Brandvain, Yaniv; Wright, Stephen I

    2016-04-01

    Evolutionary theory predicts that factors such as a small population size or low recombination rate can limit the action of natural selection. The emerging field of comparative population genomics offers an opportunity to evaluate these hypotheses. However, classical theoretical predictions assume that populations are at demographic equilibrium. This assumption is likely to be violated in the very populations researchers use to evaluate selection's limits: populations that have experienced a recent shift in population size and/or effective recombination rates. Here we highlight theory and data analyses concerning limitations on the action of natural selection in nonequilibrial populations and argue that substantial care is needed to appropriately test whether species and populations show meaningful differences in selection efficacy. A move toward model-based inferences that explicitly incorporate nonequilibrium dynamics provides a promising approach to more accurately contrast selection efficacy across populations and interpret its significance. PMID:26874998

  15. Hard and Soft Selection Revisited: How Evolution by Natural Selection Works in the Real World.

    PubMed

    Reznick, David

    2016-01-01

    The modern synthesis of evolutionary biology unified Darwin's natural selection with Mendelian genetics, but at the same time it created the dilemma of genetic load. Lewontin and Hubby's (1966) and Harris's (1966) characterization of genetic variation in natural populations increased the apparent burden of this load. Neutrality or near neutrality of genetic variation was one mechanism proposed for the revealed excessive genetic variation. Bruce Wallace coined the term "soft selection" to describe an alternative way for natural selection to operate that was consistent with observed variation. He envisioned nature as presenting ecological vacancies that could be filled by diverse genotypes. Survival and successful reproduction was a combined function of population density, genotype, and genotype frequencies, rather than a fixed value of the relative fitness of each genotype. My goal in this review is to explore the importance of soft selection in the real world. My motive and that of my colleagues as described here is not to explain what maintains genetic variation in natural populations, but rather to understand the factors that shape how organisms adapt to natural environments. We characterize how feedbacks between ecology and evolution shape both evolution and ecology. These feedbacks are mediated by density- and frequency-dependent selection, the mechanisms that underlie soft selection. Here, I report on our progress in characterizing these types of selection with a combination of a consideration of the published literature and the results from my collaborators' and my research on natural populations of guppies. PMID:26424874

  16. Toxicity and mutagenic activity of some selected Nigerian plants.

    PubMed

    Sowemimo, A A; Fakoya, F A; Awopetu, I; Omobuwajo, O R; Adesanya, S A

    2007-09-25

    The toxicity and mutagenic potential of most African plants implicated in the management of cancer have not been investigated. The ethanolic extracts of selected Nigerian plants were subsequently studied using the brine shrimp lethality tests, inhibition of telomerase activity and induction of chromosomal aberrations in vivo in rat lymphocytes. Morinda lucida root bark, Nymphaea lotus whole plant and Garcinia kola root were active in the three test systems. Bryophyllum calycinum whole plant, Annona senegalensis root, Hymenocardia acida stem bark, Erythrophleum suaveolens leaves and Spondiathus preussii stem bark were toxic to brine shrimps and caused chromosomal damage in rat lymphocytes. Ficus exasperata leaves, Chrysophyllum albidum root bark and Hibiscus sabdariffa leaves were non-toxic to all the three test systems. Chenopodium ambrosioides whole plant was non-toxic to brine shrimps and rat lymphocyte chromosomes but showed inhibition in the conventional telomerase assay indicating a possible selectivity for human chromosomes. The result justified the use of the first eight plants and Chenopodium ambrosioides in the management of cancer in south west Nigeria although they appear to be non-selective and their mode of action may be different from plant to plant. All these plants except Chenopodium ambrosioides are also mutagenic and cytotoxic. PMID:17707603

  17. Selection on soil microbiomes reveals reproducible impacts on plant function.

    PubMed

    Panke-Buisse, Kevin; Poole, Angela C; Goodrich, Julia K; Ley, Ruth E; Kao-Kniffin, Jenny

    2015-04-01

    Soil microorganisms found in the root zone impact plant growth and development, but the potential to harness these benefits is hampered by the sheer abundance and diversity of the players influencing desirable plant traits. Here, we report a high level of reproducibility of soil microbiomes in altering plant flowering time and soil functions when partnered within and between plant hosts. We used a multi-generation experimental system using Arabidopsis thaliana Col to select for soil microbiomes inducing earlier or later flowering times of their hosts. We then inoculated the selected microbiomes from the tenth generation of plantings into the soils of three additional A. thaliana genotypes (Ler, Be, RLD) and a related crucifer (Brassica rapa). With the exception of Ler, all other plant hosts showed a shift in flowering time corresponding with the inoculation of early- or late-flowering microbiomes. Analysis of the soil microbial community using 16 S rRNA gene sequencing showed distinct microbiota profiles assembling by flowering time treatment. Plant hosts grown with the late-flowering-associated microbiomes showed consequent increases in inflorescence biomass for three A. thaliana genotypes and an increase in total biomass for B. rapa. The increase in biomass was correlated with two- to five-fold enhancement of microbial extracellular enzyme activities associated with nitrogen mineralization in soils. The reproducibility of the flowering phenotype across plant hosts suggests that microbiomes can be selected to modify plant traits and coordinate changes in soil resource pools. PMID:25350154

  18. Herbivores modify selection on plant functional traits in a temperate rainforest understory.

    PubMed

    Salgado-Luarte, Cristian; Gianoli, Ernesto

    2012-08-01

    There is limited evidence regarding the adaptive value of plant functional traits in contrasting light environments. It has been suggested that changes in these traits in response to light availability can increase herbivore susceptibility. We tested the adaptive value of plant functional traits linked with carbon gain in contrasting light environments and also evaluated whether herbivores can modify selection on these traits in each light environment. In a temperate rainforest, we examined phenotypic selection on functional traits in seedlings of the pioneer tree Aristotelia chilensis growing in sun (canopy gap) and shade (forest understory) and subjected to either natural herbivory or herbivore exclusion. We found differential selection on functional traits depending on light environment. In sun, there was positive directional selection on photosynthetic rate and relative growth rate (RGR), indicating that selection favors competitive ability in a high-resource environment. Seedlings with high specific leaf area (SLA) and intermediate RGR were selected in shade, suggesting that light capture and conservative resource use are favored in the understory. Herbivores reduced the strength of positive directional selection acting on SLA in shade. We provide the first demonstration that natural herbivory rates can change the strength of selection on plant ecophysiological traits, that is, attributes whose main function is resource uptake. Research addressing the evolution of shade tolerance should incorporate the selective role of herbivores. PMID:22766937

  19. Natural and sexual selection in a monogamous historical human population

    PubMed Central

    Courtiol, Alexandre; Pettay, Jenni E.; Jokela, Markus; Rotkirch, Anna; Lummaa, Virpi

    2012-01-01

    Whether and how human populations exposed to the agricultural revolution are still affected by Darwinian selection remains controversial among social scientists, biologists, and the general public. Although methods of studying selection in natural populations are well established, our understanding of selection in humans has been limited by the availability of suitable datasets. Here, we present a study comparing the maximum strengths of natural and sexual selection in humans that includes the effects of sex and wealth on different episodes of selection. Our dataset was compiled from church records of preindustrial Finnish populations characterized by socially imposed monogamy, and it contains a complete distribution of survival, mating, and reproductive success for 5,923 individuals born 1760–1849. Individual differences in early survival and fertility (natural selection) were responsible for most variation in fitness, even among wealthier individuals. Variance in mating success explained most of the higher variance in reproductive success in males compared with females, but mating success also influenced reproductive success in females, allowing for sexual selection to operate in both sexes. The detected opportunity for selection is in line with measurements for other species but higher than most previous reports for human samples. This disparity results from biological, demographic, economic, and social differences across populations as well as from failures by most previous studies to account for variation in fitness introduced by nonreproductive individuals. Our results emphasize that the demographic, cultural, and technological changes of the last 10,000 y did not preclude the potential for natural and sexual selection in our species. PMID:22547810

  20. Surprisingly Low Limits of Selection in Plant Domestication

    PubMed Central

    Allaby, Robin G.; Kitchen, James L.; Fuller, Dorian Q.

    2015-01-01

    Current debate concerns the pace at which domesticated plants emerged from cultivated wild populations and how many genes were involved. Using an individual-based model, based on the assumptions of Haldane and Maynard Smith, respectively, we estimate that a surprisingly low number of 50–100 loci are the most that could be under selection in a cultivation regime at the selection strengths observed in the archaeological record. This finding is robust to attempts to rescue populations from extinction through selection from high standing genetic variation, gene flow, and the Maynard Smith-based model of threshold selection. Selective sweeps come at a cost, reducing the capacity of plants to adapt to new environments, which may contribute to the explanation of why selective sweeps have not been detected more frequently and why expansion of the agrarian package during the Neolithic was so frequently associated with collapse. PMID:27081302

  1. Avian use of natural versus planted woodlands in eastern South Dakota, USA

    USGS Publications Warehouse

    Bakker, K.K.; Higgins, K.F.

    2003-01-01

    We compared avian use of naturally occurring and planted woodlands in eastern South Dakota, USA, to evaluate whether planted woodlands support the same avian communities as natural woodlands. A stratified cluster sample was used to randomly select 307 public areas in which to survey planted (n = 425) and natural (n = 99) woodland patches. Eighty-five species of birds were detected in eastern South Dakota woodlands, 36 of which occurred in ??? 5 of 524 patches surveyed. The probability of occurrence for 8 of 13 woodland-obligate species was significantly greater in natural woodland habitats than in planted woodland habitats. Four of these species breed in relatively high numbers in eastern South Dakota. Only one woodland-obligate occurred less frequently in natural woodlands. Probability of occurrence for 6 edge and generalist species, including the brown-headed cowbird (Molothrus ater [Boddaert]), was significantly higher in planted woodlands. The avian community of planted woodlands was dominated by edge and generalist species. The homogeneous vegetation structure typical of planted woodlands does not appear to provide the habitat characteristics needed by woodland-obligate birds. We conclude that planted woodlands do not support significant numbers of woodland-obligate species and may negatively impact grassland-nesting birds by attracting edge and generalist bird species and predators into previously treeless habitats. Planted woodlands cannot be considered equal replacement habitats for natural woodland patches when managing for nongame woodland bird species. However, the preservation and maintenance of natural woodlands is critical for woodland-obligate species diversity in the northern Great Plains.

  2. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    NASA Astrophysics Data System (ADS)

    Thagard, Paul; Findlay, Scott

    2010-06-01

    Darwin’s theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin’s theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that derive from the intuitiveness of alternative theories. The main emotional obstacles to accepting evolution are its apparent conflict with valued beliefs about God, souls, and morality. We draw on the philosophy of science and on a psychological theory of cognitive and emotional belief revision to make suggestions about what can be done to improve acceptance of Darwinian ideas.

  3. On the importance of balancing selection in plants.

    PubMed

    Delph, Lynda F; Kelly, John K

    2014-01-01

    Balancing selection refers to a variety of selective regimes that maintain advantageous genetic diversity within populations. We review the history of the ideas regarding the types of selection that maintain such polymorphism in flowering plants, notably heterozygote advantage, negative frequency-dependent selection, and spatial heterogeneity. One shared feature of these mechanisms is that whether an allele is beneficial or detrimental is conditional on its frequency in the population. We highlight examples of balancing selection on a variety of discrete traits. These include the well-referenced case of self-incompatibility and recent evidence from species with nuclear-cytoplasmic gynodioecy, both of which exhibit trans-specific polymorphism, a hallmark of balancing selection. We also discuss and give examples of how spatial heterogeneity in particular, which is often thought unlikely to allow protected polymorphism, can maintain genetic variation in plants (which are rooted in place) as a result of microhabitat selection. Lastly, we discuss limitations of the protected polymorphism concept for quantitative traits, where selection can inflate the genetic variance without maintaining specific alleles indefinitely. We conclude that while discrete-morph variation provides the most unambiguous cases of protected polymorphism, they represent only a fraction of the balancing selection at work in plants. PMID:23952298

  4. On the importance of balancing selection in plants

    PubMed Central

    Delph, Lynda F.; Kelly, John K.

    2013-01-01

    Summary Balancing selection refers to a variety of selective regimes that maintain advantageous genetic diversity within populations. We review the history of the ideas regarding the types of selection that maintain such polymorphism in flowering plants, notably heterozygote advantage, negative frequency-dependent selection, and spatial heterogeneity. One shared feature of these mechanisms is that whether an allele is beneficial or detrimental is conditional on its frequency in the population. We highlight examples of balancing selection on a variety of discrete traits. These include the well-referenced case of self-incompatibility and recent evidence from species with nuclear-cytoplasmic gynodioecy, both of which exhibit trans-specific polymorphism, a hallmark of balancing selection. We also discuss and give examples of how spatial heterogeneity in particular, which is often thought unlikely to allow protected polymorphism, can maintain genetic variation in plants (which are rooted in place) as a result of microhabitat selection. Lastly, we discuss limitations of the protected polymorphism concept for quantitative traits, where selection can inflate the genetic variance without maintaining specific alleles indefinitely. We conclude that while discrete-morph variation provides the most unambiguous cases of protected polymorphism, they represent only a fraction of the balancing selection at work in plants. PMID:23952298

  5. Constraint, natural selection, and the evolution of human body form.

    PubMed

    Savell, Kristen R R; Auerbach, Benjamin M; Roseman, Charles C

    2016-08-23

    Variation in body form among human groups is structured by a blend of natural selection driven by local climatic conditions and random genetic drift. However, attempts to test ecogeographic hypotheses have not distinguished between adaptive traits (i.e., those that evolved as a result of selection) and those that evolved as a correlated response to selection on other traits (i.e., nonadaptive traits), complicating our understanding of the relationship between climate and morphological distinctions among populations. Here, we use evolutionary quantitative methods to test if traits previously identified as supporting ecogeographic hypotheses were actually adaptive by estimating the force of selection on individual traits needed to drive among-group differentiation. Our results show that not all associations between trait means and latitude were caused by selection acting directly on each individual trait. Although radial and tibial length and biiliac and femoral head breadth show signs of responses to directional selection matching ecogeographic hypotheses, the femur was subject to little or no directional selection despite having shorter values by latitude. Additionally, in contradiction to ecogeographic hypotheses, the humerus was under directional selection for longer values by latitude. Responses to directional selection in the tibia and radius induced a nonadaptive correlated response in the humerus that overwhelmed its own trait-specific response to selection. This result emphasizes that mean differences between groups are not good indicators of which traits are adaptations in the absence of information about covariation among characteristics. PMID:27482101

  6. Engineered Biosynthesis of Medicinally Important Plant Natural Products in Microorganisms.

    PubMed

    Zhang, Shuwei; Wang, Siyuan; Zhan, Jixun

    2016-01-01

    Plants produce structurally and functionally diverse natural products. Some of these compounds possess promising health-benefiting properties, such as resveratrol (antioxidant) curcumin (anti-inflammatory, anti-allergic and anticancer), paclitaxel (anticancer) and artemisinin (antimalarial). These compounds are produced through particular biosynthetic pathways in the plants. While supply of these medicinally important molecules relies on extraction from the producing species, recent years have seen significant advances in metabolic engineering of microorganisms for the production of plant natural products. Escherichia coli and Saccharomyces cerevisiae are the two most widely used heterologous hosts for expression of enzymes and reconstitution of plant natural product biosynthetic pathways. Total biosynthesis of many plant polyketide natural products such as curcumin and piceatannol in microorganisms has been achieved. While the late biosynthetic steps of more complex molecules such as paclitaxel and artemisinin remain to be understood, reconstitution of their partial biosynthetic pathways and microbial production of key intermediates have been successful. This review covers recent advances in understanding and engineering the biosynthesis of plant polyketides and terpenoids in microbial hosts. PMID:26456465

  7. Accumulation of heavy metals in selected medicinal plants.

    PubMed

    Sarma, Hemen; Deka, Suresh; Deka, Hemen; Saikia, Rashmi Rekha

    2011-01-01

    In this review, we evaluate the reports published between 1993 and 2011 that address the heavy metal accumulation in 88 medicinal plant species. We compare the safe limits for heavy metals set by governmental agencies vs. the levels at which such metals actually exist in selected medicinal plants. We also evaluate the uses and effectiveness of medicinal plants in health care, and assess the hazards of medicinal plant uses, in view of the growing worldwide use of medicinal plants. From our extensive review of the literature, we discovered that a maximum permissible level (MPL) of Pb is exceeded in 21 plant medicine species, Cd in 44 species, and Hg in 10 species. Vetiveria zizanioides a potential candidate species for the treatment of cardiovascular diseases absorb a wide range of heavy metals from metal-contaminated soils. We believe that this species is the single most impressive example of a potentially hazardous medicinal plant. Based on our review, we endorse the hypothesis that heavy metal accumulation by medicinal plants is mainly caused by extraction of soluble metals from contaminated soil, sediments and air. One continuing problem in protecting consumers of plant-based medicines is that permissible levels of all heavy metals in herbal medicine have not yet been standardized by regulating governmental entities. Moreover, there are few limit tests that exist for heavy metal content of medicinal plants, or permissible limits for essential dietary minerals, in most medicinal plants. The dearth of such limits hamstrings development of medicinal plant research and delays the release of either new or improved versions of medicinal plants or their components. In the present review, we emphasize that medicinal plants are often subjected to heavy metal contamination and that the levels at which these heavy metals sometimes occur exceeds permissible levels for some species. Therefore, collecting medicinal plants from areas that are, or may be, contaminated should be

  8. A natural plant growth promoter calliterpenone from a plant Callicarpa macrophylla Vahl improves the plant growth promoting effects of plant growth promoting rhizobacteria (PGPRs).

    PubMed

    Maji, Deepamala; Barnawal, Deepti; Gupta, Aakansha; King, Shikha; Singh, A K; Kalra, A

    2013-05-01

    Experiments were conducted to evaluate the efficacy of calliterpenone, a natural plant growth promoter from a shrub Callicarpa macrophylla Vahl., in enhancing the growth and yield promoting effects of plant growth promoting rhizobacteria (PGPRs), in menthol mint (Mentha arvensis L).This study is based on our previous results indicating the microbial growth promotion by calliterpenone and assumption that application of calliterpenone along with PGPRs will improve the population of PGPRs resulting in higher impacts on plant growth and yield. Of the 15 PGPRs (identified as potent ones in our laboratory), 25 μl of 0.01 mM calliterpenone (8.0 μg/100 ml) was found to be useful in improving the population of nine PGPRs in culture media. The five selected strains of PGPRs exhibiting synergy with calliterpenone in enhancing growth of maize compared to PGPR or calliterpenone alone were selected and tested on two cultivars (cvs. Kosi and Kushal) of M. arvensis. Of the five strains, Bacillus subtilis P-20 (16S rDNA sequence homologous to Accession No NR027552) and B. subtilis Daz-26 (16SrDNA sequence homologuos to Accession No GU998816) were found to be highly effective in improving the herb and essential oil yield in the cultivars Kushal and Kosi respectively when co-treated with calliterpenone. The results open up the possibilities of using a natural growth promoter along with PGPRs as a bio-agri input for sustainable and organic agriculture. PMID:23271460

  9. When natural selection gives gene function the cold shoulder.

    PubMed

    Cutter, Asher D; Jovelin, Richard

    2015-11-01

    It is tempting to invoke organismal selection as perpetually optimizing the function of any given gene. However, natural selection can drive genic functional change without improvement of biochemical activity, even to the extinction of gene activity. Detrimental mutations can creep in owing to linkage with other selectively favored loci. Selection can promote functional degradation, irrespective of genetic drift, when adaptation occurs by loss of gene function. Even stabilizing selection on a trait can lead to divergence of the underlying molecular constituents. Selfish genetic elements can also proliferate independent of any functional benefits to the host genome. Here we review the logic and evidence for these diverse processes acting in genome evolution. This collection of distinct evolutionary phenomena - while operating through easily understandable mechanisms - all contribute to the seemingly counterintuitive notion that maintenance or improvement of a gene's biochemical function sometimes do not determine its evolutionary fate. PMID:26411745

  10. Using Different Examples of Natural Selection When Teaching Biology.

    ERIC Educational Resources Information Center

    Perry, Robert T.

    1993-01-01

    Describes the following examples of natural selection for use in science instruction: sickle-cell anemia and human beings, clogged crabs, the rounding of the human head, shell color in land snails, pollinator behavior and flower color, copper tolerance in a grass, lizards and quick change, and Darwin's finches. (PR)

  11. The Nature of Selected English Teachers' Online Participation

    ERIC Educational Resources Information Center

    Rodesiler, Luke

    2015-01-01

    This article documents an investigation into the nature of selected secondary English teachers' online participation across platforms (i.e., blogs, microblogs, social networking sites) as they explored issues related to teaching, learning, and literacy. Ethnographic content analysis of online artifacts generated over approximately 10 months…

  12. Effective Assessment: Probing Students' Understanding of Natural Selection

    ERIC Educational Resources Information Center

    Stern, Luli

    2004-01-01

    Evolution by natural selection provides the conceptual framework upon which much of modern biology is based: therefore understanding core ideas about biological evolution is an essential part of scientific literacy. Nonetheless, research repeatedly shows that high school and college students have difficulties understanding the notion of natural…

  13. Reconsidering the logical structure of the theory of natural selection

    PubMed Central

    Hunt, Tam

    2014-01-01

    Natural selection has been criticized as a tautology. This would be a major problem for evolutionary biology, if true, because tautological statements can't be falsified and, therefore, can't be scientific. There is merit to this critique insofar as the theory of natural selection is indeed generally described in a tautological manner. However, natural selection can be described non-tautologically if we’re careful. Natural selection should be defined as the theory that attempts to predict and retrodict evolutionary change through environmental forces acting upon organisms. However, this re-framing comes at a cost: it reveals, based on our current knowledge of evolutionary forces, the lack of ability to make accurate predictions about expected changes except in the most simple of circumstances. I suggest that evolutionary biologists should work to develop “principles of evolution,” based on an expanded and more focused research program designed to identify common trends in evolution, which will ultimately allow us to make more accurate predictions and retrodictions about evolution. PMID:26478764

  14. Natural selection mapping of the warfarin-resistance gene

    PubMed Central

    Kohn, Michael H.; Pelz, Hans-Joachim; Wayne, Robert K.

    2000-01-01

    In theory, genes under natural selection can be revealed by unique patterns of linkage disequilibrium (LD) and polymorphism at physically linked loci. However, given the effects of recombination and mutation, the physical extent and persistence of LD patterns in natural populations is uncertain. To assess the LD signature of selection, we survey variation in 26 microsatellite loci spanning an ≈32-cM region that includes the warfarin-resistance gene (Rw) in five wild rat populations having resistance levels between 0 and 95%. We find a high frequency of heterozygote deficiency at microsatellite loci in resistant populations, and a negative association between gene diversity (H) and resistance. Contrary to previous studies, these data suggest that directional rather than overdominant selection may predominate during periods of intense anticoagulant treatment. In highly resistant populations, extensive LD was observed over a chromosome segment spanning ≈14% of rat chromosome 1. In contrast, LD in a moderately resistant population was more localized and, in conjunction with likelihood ratios, allowed assignment of Rw to a 2.2-cM interval. Within this genomic window, a diagnostic marker, D1Rat219, assigned 91% of rats to the correct resistance category. These results further demonstrate that “natural selection mapping” in field populations can detect and map major fitness-related genes, and question overdominance as the predominant mode of selection in anticoagulant-resistant rat populations. PMID:10884423

  15. Estimating selection through male fitness: three complementary methods illuminate the nature and causes of selection on flowering time.

    PubMed

    Austen, Emily J; Weis, Arthur E

    2016-02-24

    Our understanding of selection through male fitness is limited by the resource demands and indirect nature of the best available genetic techniques. Applying complementary, independent approaches to this problem can help clarify evolution through male function. We applied three methods to estimate selection on flowering time through male fitness in experimental populations of the annual plant Brassica rapa: (i) an analysis of mating opportunity based on flower production schedules, (ii) genetic paternity analysis, and (iii) a novel approach based on principles of experimental evolution. Selection differentials estimated by the first method disagreed with those estimated by the other two, indicating that mating opportunity was not the principal driver of selection on flowering time. The genetic and experimental evolution methods exhibited striking agreement overall, but a slight discrepancy between the two suggested that negative environmental covariance between age at flowering and male fitness may have contributed to phenotypic selection. Together, the three methods enriched our understanding of selection on flowering time, from mating opportunity to phenotypic selection to evolutionary response. The novel experimental evolution method may provide a means of examining selection through male fitness when genetic paternity analysis is not possible. PMID:26911957

  16. Plant extracts as natural antioxidants in meat and meat products.

    PubMed

    Shah, Manzoor Ahmad; Bosco, Sowriappan John Don; Mir, Shabir Ahmad

    2014-09-01

    Antioxidants are used to minimize the oxidative changes in meat and meat products. Oxidative changes may have negative effects on the quality of meat and meat products, causing changes in their sensory and nutritional properties. Although synthetic antioxidants have already been used but in recent years, the demand for natural antioxidants has been increased mainly because of adverse effects of synthetic antioxidants. Thus most of the recent investigations have been directed towards the identification of natural antioxidants from various plant sources. Plant extracts have been prepared using different solvents and extraction methods. Grape seed, green tea, pine bark, rosemary, pomegranate, nettle and cinnamon have exhibited similar or better antioxidant properties compared to some synthetic ones. This review provides the recent information on plant extracts used as natural antioxidants in meat and meat products, specifically red meat. PMID:24824531

  17. Natural selection drives the evolution of ant life cycles

    PubMed Central

    Wilson, Edward O.; Nowak, Martin A.

    2014-01-01

    The genetic origin of advanced social organization has long been one of the outstanding problems of evolutionary biology. Here we present an analysis of the major steps in ant evolution, based for the first time, to our knowledge, on combined recent advances in paleontology, phylogeny, and the study of contemporary life histories. We provide evidence of the causal forces of natural selection shaping several key phenomena: (i) the relative lateness and rarity in geological time of the emergence of eusociality in ants and other animal phylads; (ii) the prevalence of monogamy at the time of evolutionary origin; and (iii) the female-biased sex allocation observed in many ant species. We argue that a clear understanding of the evolution of social insects can emerge if, in addition to relatedness-based arguments, we take into account key factors of natural history and study how natural selection acts on alleles that modify social behavior. PMID:25114217

  18. The Divergence and Natural Selection of Autocatalytic Primordial Metabolic Systems

    NASA Astrophysics Data System (ADS)

    Marakushev, Sergey A.; Belonogova, Ol'ga V.

    2013-06-01

    The diversity of the central metabolism of modern organisms is caused by the existence of a few metabolic modules, combination of which produces multiple metabolic pathways. This paper analyzes biomimetically reconstructed coupled autocatalytic cycles as the basis of ancestral metabolic systems. The mechanism for natural selection and evolution in autocatalytic chemical systems may be affected by natural homeostatic parameters such as ambient chemical potentials, temperature, and pressure. Competition between separate parts of an autocatalytic network with positive-plus-negative feedback resulted in the formation of primordial autotrophic, mixotrophic, and heterotrophic metabolic systems. This work examined the last common ancestor of a set of coupled metabolic cycles in a population of protocells. Physical-chemical properties of these cycles determined the main principles of natural selection for the ancestral Bacteria and Archaea taxa.

  19. Biological fitness and the fundamental theorem of natural selection.

    PubMed

    Grafen, Alan

    2015-07-01

    Fisher's fundamental theorem of natural selection is proved satisfactorily for the first time, resolving confusions in the literature about the nature of reproductive value and fitness. Reproductive value is defined following Fisher, without reference to genetic variation, and fitness is the proportional rate of increase in an individual's contribution to the demographic population size. The mean value of fitness is the same in each age class, and it also equals the population's Malthusian parameter. The statement and derivation are regarded as settled here, and so the general biological significance of the fundamental theorem can be debated. The main purpose of the theorem is to find a quantitative measure of the effect of natural selection in a Mendelian system, thus founding Darwinism on Mendelism and identifying the design criterion for biological adaptation, embodied in Fisher's ingenious definition of fitness. The relevance of the newly understood theorem to five current research areas is discussed. PMID:26098334

  20. The insufficient part of abiogenesis theory - natural selection

    NASA Astrophysics Data System (ADS)

    Ploompuu, Tõnu

    2016-04-01

    Abiogenesis has already been studied for a whole century. There have been studies on the synthesis of precursors of biopolymers, concentration processes and polymerization pathways, sites of initiation of life. Autoreplication has been explained. Protocells have been constructed from abiogenic membranes. But one essential aspect for life - the natural selection - has been marginalized in these investigations. Despite the convincing use of natural selection in biology for one and half century, it has not been used sufficiently in the models of the beginning of life. Pictorially - Darwin's pond model is used without darwinism. This generates an unnecessary interruption on the path for understanding the process. Natural selection is essential in abiogenesis, in the genesis of biological information system. A selection of more collaborative autoreplicate biopolymers and the depolymerisation of others was required. Only natural selection was able to combine biopolymer molecules for life. The primary natural selection can operate only in an environment with variable physical and chemical conditions. The selective agent must constantly fluctuate during a long time span and a large area. Formation of the simplest complex of life needs homeostasis. The best sites for constant fluctuations are littoral areas of oceans. Two very constant fluctuations - waves and tides - occur there. The best conditions for the origin of life were exactly in the end of the Late Heavy Bombardment at temperature nealy 100° C. Earth's surface was then protected against the UV destruction by a thick cloud cover. High evaporation at the hotter parts of shore rocks increased the concentration of the primordial soup and there was excellent selective power by routine water level fluctuations. Because of the water level fluctuations salty ocean water and fresh water from continuous downpours alternated at the littoral zones. In low temperatures the formation of life would be hindered by UV

  1. Natural Selection VS. Random Drift: Evidence from Temporal Variation in Allele Frequencies in Nature

    PubMed Central

    Mueller, Laurence D.; Barr, Lorraine G.; Ayala, Francisco J.

    1985-01-01

    We have obtained monthly samples of two species, Drosophila pseudoobscura and Drosophila persimilis, in a natural population from Napa County, California. In each species, about 300 genes have been assayed by electrophoresis for each of seven enzyme loci in each monthly sample from March 1972 to June 1975. Using statistical methods developed for the purpose, we have examined whether the allele frequencies at different loci vary in a correlated fashion. The methods used do not detect natural selection when it is deterministic (e.g., overdominance or directional selection), but only when alleles at different loci vary simultaneously in response to the same environmental variations. Moreover, only relatively large fitness differences (of the order of 15%) are detectable. We have found strong evidence of correlated allele frequency variation in 13–20% of the cases examined. We interpret this as evidence that natural selection plays a major role in the evolution of protein polymorphisms in nature. PMID:4054608

  2. Selectable marker genes in transgenic plants: applications, alternatives and biosafety.

    PubMed

    Miki, Brian; McHugh, Sylvia

    2004-02-01

    Approximately fifty marker genes used for transgenic and transplastomic plant research or crop development have been assessed for efficiency, biosafety, scientific applications and commercialization. Selectable marker genes can be divided into several categories depending on whether they confer positive or negative selection and whether selection is conditional or non-conditional on the presence of external substrates. Positive selectable marker genes are defined as those that promote the growth of transformed tissue whereas negative selectable marker genes result in the death of the transformed tissue. The positive selectable marker genes that are conditional on the use of toxic agents, such as antibiotics, herbicides or drugs were the first to be developed and exploited. More recent developments include positive selectable marker genes that are conditional on non-toxic agents that may be substrates for growth or that induce growth and differentiation of the transformed tissues. Newer strategies include positive selectable marker genes which are not conditional on external substrates but which alter the physiological processes that govern plant development. A valuable companion to the selectable marker genes are the reporter genes, which do not provide a cell with a selective advantage, but which can be used to monitor transgenic events and manually separate transgenic material from non-transformed material. They fall into two categories depending on whether they are conditional or non-conditional on the presence of external substrates. Some reporter genes can be adapted to function as selectable marker genes through the development of novel substrates. Despite the large number of marker genes that exist for plants, only a few marker genes are used for most plant research and crop development. As the production of transgenic plants is labor intensive, expensive and difficult for most species, practical issues govern the choice of selectable marker genes that are

  3. Historical intensity of natural selection for resistance to tuberculosis.

    PubMed Central

    Lipsitch, Marc; Sousa, Alexandra O

    2002-01-01

    Infections have long been thought to exert natural selection on humans. Infectious disease resistance is frequently invoked as a mechanism shaping human genetic diversity, but such hypotheses have rarely been quantitatively evaluated with direct measures of disease-related mortality. Enhancement of genetically determined resistance to tuberculosis by natural selection has been proposed as a factor explaining the decline of tuberculosis in Europe and North America in the period 1830-1950 (before the advent of antimicrobial chemotherapy) and the apparently reduced susceptibility of Europeans and their descendants to tuberculosis infection and/or disease. We used Swedish vital statistics from 1891 to 1900 to estimate that individuals who escaped mortality from pulmonary tuberculosis (PTB) during the European tuberculosis epidemic would have enjoyed a fitness advantage of 7-15% per generation compared to individuals who were susceptible to PTB mortality; individuals with 50% protection would have had a selection coefficient of 4-7%/generation. Selection during the peak of the European TB epidemic could have substantially reduced the frequency of already rare alleles conferring increased susceptibility to PTB mortality, but only if the phenotypic effects of these alleles were very large. However, if resistant alleles were rare at the beginning of this period, 300 years would not have been long enough for such selection to increase their frequency to epidemiologically significant levels. Reductions in the frequency of rare susceptibility alleles could have played at most a small part in the decline of the epidemic in the century preceding 1950. Natural selection by PTB deaths during the European TB epidemic alone cannot account for the presently low level of TB disease observed among Europeans and their descendants just prior to the appearance of antibiotic treatment. PMID:12196403

  4. Plants for Play: A Plant Selection Guide for Children's Outdoor Environments.

    ERIC Educational Resources Information Center

    Moore, Robin C.

    This book presents guidelines in the design and management of children's landscapes and reveals the importance of plants as a resource for play and child development. It identifies plants by function, i.e., their sensory values, play values, food production, seasonal interest, shade quality, screens against natural barriers, wildlife enhancement,…

  5. Natural selection on thermal performance in a novel thermal environment

    PubMed Central

    Logan, Michael L.; Cox, Robert M.; Calsbeek, Ryan

    2014-01-01

    Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation to changing conditions. Here, we mimic the effects of climate change by experimentally transplanting a population of Anolis sagrei lizards to a novel thermal environment. Transplanted lizards experienced warmer and more thermally variable conditions, which resulted in strong directional selection on thermal performance traits. These same traits were not under selection in a reference population studied in a less thermally stressful environment. Our results indicate that climate change can exert strong natural selection on tropical ectotherms, despite their ability to thermoregulate behaviorally. To the extent that thermal performance traits are heritable, populations may be capable of rapid adaptation to anthropogenic warming. PMID:25225361

  6. Natural selection on thermal performance in a novel thermal environment.

    PubMed

    Logan, Michael L; Cox, Robert M; Calsbeek, Ryan

    2014-09-30

    Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation to changing conditions. Here, we mimic the effects of climate change by experimentally transplanting a population of Anolis sagrei lizards to a novel thermal environment. Transplanted lizards experienced warmer and more thermally variable conditions, which resulted in strong directional selection on thermal performance traits. These same traits were not under selection in a reference population studied in a less thermally stressful environment. Our results indicate that climate change can exert strong natural selection on tropical ectotherms, despite their ability to thermoregulate behaviorally. To the extent that thermal performance traits are heritable, populations may be capable of rapid adaptation to anthropogenic warming. PMID:25225361

  7. Parasite-mediated disruptive selection in a natural Daphnia population

    PubMed Central

    2008-01-01

    Background A mismatch has emerged between models and data of host-parasite evolution. Theory readily predicts that parasites can promote host diversity through mechanisms such as disruptive selection. Yet, despite these predictions, empirical evidence for parasite-mediated increases in host diversity remains surprisingly scant. Results Here, we document parasite-mediated disruptive selection on a natural Daphnia population during a parasite epidemic. The mean susceptibility of clones collected from the population before and after the epidemic did not differ, but clonal variance and broad-sense heritability of post-epidemic clones were significantly greater, indicating disruptive selection and rapid evolution. A maximum likelihood method that we developed for detecting selection on natural populations also suggests disruptive selection during the epidemic: the distribution of susceptibilities in the population shifted from unimodal prior to the epidemic to bimodal after the epidemic. Interestingly, this same bimodal distribution was retained after a generation of sexual reproduction. Conclusion These results provide rare empirical support for parasite-driven increases in host genetic diversity, and suggest that this increase can occur rapidly. PMID:18328099

  8. Genome-wide polymorphisms show unexpected targets of natural selection.

    PubMed

    Pespeni, Melissa H; Garfield, David A; Manier, Mollie K; Palumbi, Stephen R

    2012-04-01

    Natural selection can act on all the expressed genes of an individual, leaving signatures of genetic differentiation or diversity at many loci across the genome. New power to assay these genome-wide effects of selection comes from associating multi-locus patterns of polymorphism with gene expression and function. Here, we performed one of the first genome-wide surveys in a marine species, comparing purple sea urchins, Strongylocentrotus purpuratus, from two distant locations along the species' wide latitudinal range. We examined 9112 polymorphic loci from upstream non-coding and coding regions of genes for signatures of selection with respect to gene function and tissue- and ontogenetic gene expression. We found that genetic differentiation (F(ST)) varied significantly across functional gene classes. The strongest enrichment occurred in the upstream regions of E3 ligase genes, enzymes known to regulate protein abundance during development and environmental stress. We found enrichment for high heterozygosity in genes directly involved in immune response, particularly NALP genes, which mediate pro-inflammatory signals during bacterial infection. We also found higher heterozygosity in immune genes in the southern population, where disease incidence and pathogen diversity are greater. Similar to the major histocompatibility complex in mammals, balancing selection may enhance genetic diversity in the innate immune system genes of this invertebrate. Overall, our results show that how genome-wide polymorphism data coupled with growing databases on gene function and expression can combine to detect otherwise hidden signals of selection in natural populations. PMID:21993504

  9. Ontogenetic selection on hatchery salmon in the wild: natural selection on artificial phenotypes.

    PubMed

    Bailey, Michael M; Lachapelle, Kevin A; Kinnison, Michael T

    2010-07-01

    Captive rearing often alters the phenotypes of organisms that are destined for release into the wild. Natural selection on these unnatural phenotypes could have important consequences for the utility of captive rearing as a restoration approach. We show that normal hatchery practices significantly advance the development of endangered Atlantic salmon (Salmo salar) fry by 30+ days. As a result, hatchery fry might be expected to face strong natural selection resulting from their developmental asynchrony. We investigated patterns of ontogenetic selection acting on hatchery produced salmon fry by experimentally manipulating fry development stage at stocking. Contrary to simple predictions, we found evidence for strong stabilizing selection on the ontogeny of unfed hatchery fry, with weaker evidence for positive directional selection on the ontogeny of fed fry. These selection patterns suggest a seasonally independent tradeoff between abiotic or biotic selection favoring advanced development and physiological selection linked to risk of starvation in unfed fry. We show, through a heuristic exercise, how such selection on ontogeny may exacerbate problems in restoration efforts by impairing fry productivity and reducing effective population sizes by 13-81%. PMID:25567929

  10. Conserving natural enemies with flowering plants: Estimating attractiveness

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flower morphology and volatile chemistry are related to the number and type of parasitoids captured in Malaise traps baited with various flowers, including native plants. Such information could guide attempts to conserve natural enemies through modifications of agricultural landscapes such as interc...

  11. Selection and Breeding of Plant Cultivars to Minimize Cadmium Accumulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural variation occurs in the uptake and distribution of essential and nonessential trace elements among crop species and among cultivars within species. Such variation can be responsible for trace element deficiencies and toxicities, which in turn can affect the quality of food. Plant breeding ...

  12. Natural Gamma Emitters after a Selective Chemical Separation of a TENORM residue: Preliminary Results

    SciTech Connect

    Alves de Freitas, Antonio; Abrao, Alcidio; Godoy dos Santos, Adir Janete; Pecequilo, Brigitte Roxana Soreanu

    2008-08-07

    An analytical procedure was established in order to obtain selective fractions containing radium isotopes ({sup 228}Ra), thorium ({sup 232}Th), and rare earths from RETOTER (REsiduo de TOrio e TErras Raras), a solid residue rich in rare earth elements, thorium isotopes and small amount of natural uranium generated from the operation of a thorium pilot plant for purification and production of pure thorium nitrate at IPEN -CNEN/SP. The paper presents preliminary results of {sup 228}Ra, {sup 226}Ra, {sup 238}U, {sup 210}Pb, and {sup 40}K concentrations in the selective fractions and total residue determined by high-resolution gamma spectroscopy, considering radioactive equilibrium of the samples.

  13. Natural selection and infectious disease in human populations

    PubMed Central

    Karlsson, Elinor K.; Kwiatkowski, Dominic P.; Sabeti, Pardis C.

    2015-01-01

    The ancient biological 'arms race' between microbial pathogens and humans has shaped genetic variation in modern populations, and this has important implications for the growing field of medical genomics. As humans migrated throughout the world, populations encountered distinct pathogens, and natural selection increased the prevalence of alleles that are advantageous in the new ecosystems in both host and pathogens. This ancient history now influences human infectious disease susceptibility and microbiome homeostasis, and contributes to common diseases that show geographical disparities, such as autoimmune and metabolic disorders. Using new high-throughput technologies, analytical methods and expanding public data resources, the investigation of natural selection is leading to new insights into the function and dysfunction of human biology. PMID:24776769

  14. Perspectives for genomic selection applications and research in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genomic selection (GS) has created a lot of excitement and expectations in the animal and plant breeding research communities. In this review, we briefly describe how genomic prediction can be integrated into breeding efforts and point out achievements and areas where more research is needed. GS pro...

  15. Compactifying de Sitter space naturally selects a small cosmological constant

    NASA Astrophysics Data System (ADS)

    Brown, Adam R.; Dahlen, Alex; Masoumi, Ali

    2014-12-01

    We study compactifications of D -dimensional de Sitter space with a q -form flux down to D -N q dimensions. We show that for (N -1 )(q -1 )≥2 there are double-exponentially or even infinitely many compact de Sitter vacua, and that their effective cosmological constants accumulate at zero. This population explosion of Λ ≪1 de Sitters arises by a mechanism analogous to natural selection.

  16. The theory of natural selection of Alfred Russel Wallace FRS.

    PubMed

    Bulmer, Michael

    2005-05-22

    Wallace's 1858 paper 'On the tendency of varieties to depart indefinitely from the original type' is often thought to present a theory of natural selection identical with that of Darwin. Examination of Wallace's argument shows that it is different from Darwin's because Wallace thought that an inferior variety could coexist with a superior variety until environmental deterioration forced the extinction of the inferior one. Other interpretations of Wallace's argument are re-examined in the light of this finding. PMID:16116703

  17. Programed Death is Favored by Natural Selection in Spatial Systems

    NASA Astrophysics Data System (ADS)

    Werfel, Justin; Ingber, Donald E.; Bar-Yam, Yaneer

    2015-06-01

    Standard evolutionary theories of aging and mortality, implicitly based on mean-field assumptions, hold that programed mortality is untenable, as it opposes direct individual benefit. We show that in spatial models with local reproduction, programed deaths instead robustly result in long-term benefit to a lineage, by reducing local environmental resource depletion via spatiotemporal patterns causing feedback over many generations. Results are robust to model variations, implying that direct selection for shorter life span may be quite widespread in nature.

  18. Natural selection maintains the transcribed LTR retrotransposons in Nosema bombycis.

    PubMed

    Xiang, Heng; Pan, Guoqing; Zhang, Ruizhi; Xu, Jinshan; Li, Tian; Li, Wenle; Zhou, Zeyang; Xiang, Zhonghuai

    2010-05-01

    Eight intact LTR retrotransposons (Nbr1-Nbr8) have been previously characterized from the genome of Nosema bombycis, a eukaryotic parasite with a compact and reduced genome. Here we describe six novel transcribed Nbr elements (Nbr9-Nbr14) identified through either cDNA library or RT-PCR. Like previously determined ones, all of them belong to the Ty3/Gypsy superfamily. Retrotransposon diversity and incomplete domains with insertions (Nbr12), deletions (Nbr11) and in-frame stop codons in coding regions (Nbr9) were detected, suggesting that both defective and loss events of LTR retrotransposon have happened in N. bombycis genome. Analysis of selection showed that strong purifying selection acts on all elements except Nbr11. This implies that selective pressure keeps both these Nbrs and their functions in genome. Interestingly, Nbr11 is under positive selection and some positively selected codons were identified, indicating that new functionality might have evolved in the Nbr11 retrotransposon. Unlike other transposable elements, Nbr11 has integrated into a conserved syntenic block and probably resulted in the inversion of both flanking regions. This demonstrates that transposable element is an important factor for the reshuffling and evolution of their host genomes, and may be maintained under natural selection. PMID:20513631

  19. Natural Selection and Genetic Diversity in the Butterfly Heliconius melpomene.

    PubMed

    Martin, Simon H; Möst, Markus; Palmer, William J; Salazar, Camilo; McMillan, W Owen; Jiggins, Francis M; Jiggins, Chris D

    2016-05-01

    A combination of selective and neutral evolutionary forces shape patterns of genetic diversity in nature. Among the insects, most previous analyses of the roles of drift and selection in shaping variation across the genome have focused on the genus Drosophila A more complete understanding of these forces will come from analyzing other taxa that differ in population demography and other aspects of biology. We have analyzed diversity and signatures of selection in the neotropical Heliconius butterflies using resequenced genomes from 58 wild-caught individuals of Heliconius melpomene and another 21 resequenced genomes representing 11 related species. By comparing intraspecific diversity and interspecific divergence, we estimate that 31% of amino acid substitutions between Heliconius species are adaptive. Diversity at putatively neutral sites is negatively correlated with the local density of coding sites as well as nonsynonymous substitutions and positively correlated with recombination rate, indicating widespread linked selection. This process also manifests in significantly reduced diversity on longer chromosomes, consistent with lower recombination rates. Although hitchhiking around beneficial nonsynonymous mutations has significantly shaped genetic variation in H. melpomene, evidence for strong selective sweeps is limited overall. We did however identify two regions where distinct haplotypes have swept in different populations, leading to increased population differentiation. On the whole, our study suggests that positive selection is less pervasive in these butterflies as compared to fruit flies, a fact that curiously results in very similar levels of neutral diversity in these very different insects. PMID:27017626

  20. Natural Selection and Genetic Diversity in the Butterfly Heliconius melpomene

    PubMed Central

    Martin, Simon H.; Möst, Markus; Palmer, William J.; Salazar, Camilo; McMillan, W. Owen; Jiggins, Francis M.; Jiggins, Chris D.

    2016-01-01

    A combination of selective and neutral evolutionary forces shape patterns of genetic diversity in nature. Among the insects, most previous analyses of the roles of drift and selection in shaping variation across the genome have focused on the genus Drosophila. A more complete understanding of these forces will come from analyzing other taxa that differ in population demography and other aspects of biology. We have analyzed diversity and signatures of selection in the neotropical Heliconius butterflies using resequenced genomes from 58 wild-caught individuals of Heliconius melpomene and another 21 resequenced genomes representing 11 related species. By comparing intraspecific diversity and interspecific divergence, we estimate that 31% of amino acid substitutions between Heliconius species are adaptive. Diversity at putatively neutral sites is negatively correlated with the local density of coding sites as well as nonsynonymous substitutions and positively correlated with recombination rate, indicating widespread linked selection. This process also manifests in significantly reduced diversity on longer chromosomes, consistent with lower recombination rates. Although hitchhiking around beneficial nonsynonymous mutations has significantly shaped genetic variation in H. melpomene, evidence for strong selective sweeps is limited overall. We did however identify two regions where distinct haplotypes have swept in different populations, leading to increased population differentiation. On the whole, our study suggests that positive selection is less pervasive in these butterflies as compared to fruit flies, a fact that curiously results in very similar levels of neutral diversity in these very different insects. PMID:27017626

  1. Cyclone Tolerance in New World Arecaceae: Biogeographic Variation and Abiotic Natural Selection

    PubMed Central

    Griffith, M. Patrick; Noblick, Larry R.; Dowe, John L.; Husby, Chad E.; Calonje, Michael A.

    2008-01-01

    Background and Aims Consistent abiotic factors can affect directional selection; cyclones are abiotic phenomena with near-discrete geographic limits. The current study investigates selective pressure of cyclones on plants at the species level, testing for possible natural selection. Methods New World Arecaceae (palms) are used as a model system, as plants with monopodial, unbranched arborescent form are most directly affected by the selective pressure of wind load. Living specimens of known provenance grown at a common site were affected by the same cyclone. Data on percentage mortality were compiled and analysed in biogeographic and phylogenetic contexts. Key Results Palms of cyclone-prone provenance exhibited a much lower (one order of magnitude) range in cyclone tolerance, and significantly lower (P < 0·001) mean percentage mortality than collections from cyclone-free areas. Palms of cyclone-free provenance had much greater variation in tolerance, and significantly greater mean percentage mortality. A test for serial independence recovered no significant phylogenetic autocorrelation of percentage mortality. Conclusions Variation in cyclone tolerance in New World Arecaceae correlates with biogeography, and is not confounded with phylogeny. These results suggest natural selection of cyclone tolerance in cyclone-prone areas. PMID:18669575

  2. The incidence and selection of multiple mating in plants

    PubMed Central

    Pannell, John R.; Labouche, Anne-Marie

    2013-01-01

    Mating with more than one pollen donor, or polyandry, is common in land plants. In flowering plants, polyandry occurs when the pollen from different potential sires is distributed among the fruits of a single individual, or when pollen from more than one donor is deposited on the same stigma. Because polyandry typically leads to multiple paternity among or within fruits, it can be indirectly inferred on the basis of paternity analysis using molecular markers. A review of the literature indicates that polyandry is probably ubiquitous in plants except those that habitually self-fertilize, or that disperse their pollen in pollen packages, such as polyads or pollinia. Multiple mating may increase plants' female component by alleviating pollen limitation or by promoting competition among pollen grains from different potential sires. Accordingly, a number of traits have evolved that should promote polyandry at the flower level from the female's point of view, e.g. the prolongation of stigma receptivity or increases in stigma size. However, many floral traits, such as attractiveness, the physical manipulation of pollinators and pollen-dispensing mechanisms that lead to polyandrous pollination, have probably evolved in response to selection to promote male siring success in general, so that polyandry might often best be seen as a by-product of selection to enhance outcross siring success. In this sense, polyandry in plants is similar to geitonogamy (selfing caused by pollen transfer among flowers of the same plant), because both polyandry and geitonogamy probably result from selection to promote outcross siring success, although geitonogamy is almost always deleterious while polyandry in plants will seldom be so. PMID:23339242

  3. Preventing Alzheimer's disease by means of natural selection.

    PubMed

    Demetrius, Lloyd A; Driver, Jane A

    2015-01-01

    The amyloid cascade model for the origin of sporadic forms of Alzheimer's disease (AD) posits that the imbalance in the production and clearance of beta-amyloid is a necessary condition for the disease. A competing theory called the entropic selection hypothesis asserts that the primary cause of sporadic AD is age-induced mitochondrial dysregulation and the following cascade of events: (i) metabolic reprogramming—the upregulation of oxidative phosphorylation in compensation for insufficient energy production in neurons, (ii) natural selection—competition between intact and reprogrammed neurons for energy substrates and (iii) propagation—the spread of the disease due to the selective advantage of neurons with upregulated metabolism. Experimental studies to evaluate the predictions of the amyloid cascade model are being continually retuned to accommodate conflicts of the predictions with empirical data. Clinical trials of treatments for AD based on anti-amyloid therapy have been unsuccessful. We contend that these anomalies and failures stem from a fundamental deficit of the amyloid hypothesis: the model derives from a nuclear-genomic perspective of sporadic AD and discounts the bioenergetic processes that characterize the progression of most age-related disorders. In this article, we review the anomalies of the amyloid model and the theoretical and empirical support for the entropic selection theory. We also discuss the new therapeutic strategies based on natural selection which the model proposes. PMID:25551134

  4. Natural selection against a circadian clock gene mutation in mice

    PubMed Central

    Spoelstra, Kamiel; Wikelski, Martin; Daan, Serge; Loudon, Andrew S. I.; Hau, Michaela

    2016-01-01

    Circadian rhythms with an endogenous period close to or equal to the natural light–dark cycle are considered evolutionarily adaptive (“circadian resonance hypothesis”). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness. PMID:26715747

  5. Natural selection against a circadian clock gene mutation in mice.

    PubMed

    Spoelstra, Kamiel; Wikelski, Martin; Daan, Serge; Loudon, Andrew S I; Hau, Michaela

    2016-01-19

    Circadian rhythms with an endogenous period close to or equal to the natural light-dark cycle are considered evolutionarily adaptive ("circadian resonance hypothesis"). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness. PMID:26715747

  6. Preventing Alzheimer's disease by means of natural selection

    PubMed Central

    Demetrius, Lloyd A.; Driver, Jane A.

    2015-01-01

    The amyloid cascade model for the origin of sporadic forms of Alzheimer's disease (AD) posits that the imbalance in the production and clearance of beta-amyloid is a necessary condition for the disease. A competing theory called the entropic selection hypothesis asserts that the primary cause of sporadic AD is age-induced mitochondrial dysregulation and the following cascade of events: (i) metabolic reprogramming—the upregulation of oxidative phosphorylation in compensation for insufficient energy production in neurons, (ii) natural selection—competition between intact and reprogrammed neurons for energy substrates and (iii) propagation—the spread of the disease due to the selective advantage of neurons with upregulated metabolism. Experimental studies to evaluate the predictions of the amyloid cascade model are being continually retuned to accommodate conflicts of the predictions with empirical data. Clinical trials of treatments for AD based on anti-amyloid therapy have been unsuccessful. We contend that these anomalies and failures stem from a fundamental deficit of the amyloid hypothesis: the model derives from a nuclear-genomic perspective of sporadic AD and discounts the bioenergetic processes that characterize the progression of most age-related disorders. In this article, we review the anomalies of the amyloid model and the theoretical and empirical support for the entropic selection theory. We also discuss the new therapeutic strategies based on natural selection which the model proposes. PMID:25551134

  7. Effective selection of transgenic papaya plants with the PMI/Man selection system.

    PubMed

    Zhu, Yun J; Agbayani, Ricelle; McCafferty, Heather; Albert, Henrik H; Moore, Paul H

    2005-09-01

    The selectable marker gene phospho-mannose isomerase (pmi), which encodes the enzyme phospho-mannose isomerase (PMI) to enable selection of transformed cell lines on media containing mannose (Man), was evaluated for genetic transformation of papaya (Carica papaya L.). We found that papaya embryogenic calli have little or no PMI activity and cannot utilize Man as a carbon source; however, when calli were transformed with a pmi gene, the PMI activity was greatly increased and they could utilize Man as efficiently as sucrose. Plants regenerated from selected callus lines also exhibited PMI activity but at a lower specific activity level. Our transformation efficiency with Man selection was higher than that reported using antibiotic selection or with a visual marker. For papaya, the PMI/Man selection system for producing transgenic plants is a highly efficient addition to previously published methods for selection and may facilitate the stacking of multiple transgenes of interest. Additionally, since the PMI/Man selection system does not involve antibiotic or herbicide resistance genes, its use might reduce environmental concerns about the potential flow of those genes into related plant populations. PMID:15812659

  8. Inhibition of human pathogenic fungi by ethnobotanically selected plant extracts.

    PubMed

    Ficker, Christine E; Arnason, J T; Vindas, P S; Alvarez, L P; Akpagana, K; Gbéassor, M; De Souza, C; Smith, M L

    2003-02-01

    In this study, 36 extracts derived from 29 plant species selected using an ethnobotanical approach were tested for antifungal activity against a taxonomically diverse group of 13 human pathogenic fungi. We compared the inhibitory characteristics of these plant extracts with those of the commonly used antifungals, amphotericin B and ketoconazole, and the plant-derived antifungal, berberine. Several plant extracts, notably those from Zingiber officinale (ginger) and Juglans cinerea (butternut), had pronounced antifungal activity against a wide variety of fungi, including strains that were highly resistant to amphotericin B and ketoconazole. Further exploration of Z. officinale as an antifungal is warranted as this species is generally regarded as safe for human consumption. PMID:12588480

  9. Natural selection in the field and the classroom

    NASA Astrophysics Data System (ADS)

    Andrews, Tessa Marie

    This dissertation examined natural selection in westslope cutthroat trout (Oncorhynchus clarkii lewisi) and undergraduate learning in the subject area natural selection. Translocation---moving individuals to a new habitat to establish, re-establish or supplement a population---is a crucial management strategy for cutthroat trout. One of the major questions managers face in a translocation is which population(s) should contribute individuals? Unfortunately, we often know little about the differences among potential contributing population. The goal of the first half of this dissertation was to look for differences in performance among individuals from five populations of westslope cutthroat trout. I assessed survival, growth, and condition (Chapter 2) and dispersal (Chapter 3) following the translocation of embryos from these five populations to six introduction sites in Cherry Creek. No differences existed among these populations in relative survival, growth, or condition at age 1 or 2. In contrast, statistically significant differences existed in dispersal distance among these populations. These differences were consistent across some, but not all, introduction locations. As our knowledge of evolutionary biology has continued to grow, so too has our knowledge of how students learn evolution. Students taught using active learning strategies can learn substantially more about complex scientific concepts than students taught using primarily lectures. The goal of the second half of this dissertation was to further examine how students learn natural selection and how instructors facilitate that learning. I conducted a national survey of the relationship between an instructor's use of active learning strategies and how much students learned about natural selection (Chapter 4). I used a random sample of instructors from the largest and most prestigious universities in the country so that my results could be inferred to this large population of instructors. The degree to

  10. Using David Lack's Observations of Finch Beak Size to Teach Natural Selection & the Nature of Science

    ERIC Educational Resources Information Center

    Bierema, Andrea M.-K.; Rudge, David W.

    2014-01-01

    One of the key aspects of natural selection is competition, yet the concept of competition is not necessarily emphasized in explanations of natural selection. Because of this, we developed an activity for our class that focuses on competition and provides an example of the effects of competition on natural selection. This hands-on activity models…

  11. Methods of natural gas liquefaction and natural gas liquefaction plants utilizing multiple and varying gas streams

    SciTech Connect

    Wilding, Bruce M; Turner, Terry D

    2014-12-02

    A method of natural gas liquefaction may include cooling a gaseous NG process stream to form a liquid NG process stream. The method may further include directing the first tail gas stream out of a plant at a first pressure and directing a second tail gas stream out of the plant at a second pressure. An additional method of natural gas liquefaction may include separating CO.sub.2 from a liquid NG process stream and processing the CO.sub.2 to provide a CO.sub.2 product stream. Another method of natural gas liquefaction may include combining a marginal gaseous NG process stream with a secondary substantially pure NG stream to provide an improved gaseous NG process stream. Additionally, a NG liquefaction plant may include a first tail gas outlet, and at least a second tail gas outlet, the at least a second tail gas outlet separate from the first tail gas outlet.

  12. Joint phenotypes, evolutionary conflict and the fundamental theorem of natural selection

    PubMed Central

    Queller, David C.

    2014-01-01

    Multiple organisms can sometimes affect a common phenotype. For example, the portion of a leaf eaten by an insect is a joint phenotype of the plant and insect and the amount of food obtained by an offspring can be a joint trait with its mother. Here, I describe the evolution of joint phenotypes in quantitative genetic terms. A joint phenotype for multiple species evolves as the sum of additive genetic variances in each species, weighted by the selection on each species. Selective conflict between the interactants occurs when selection takes opposite signs on the joint phenotype. The mean fitness of a population changes not just through its own genetic variance but also through the genetic variance for its fitness that resides in other species, an update of Fisher's fundamental theorem of natural selection. Some similar results, using inclusive fitness, apply to within-species interactions. The models provide a framework for understanding evolutionary conflicts at all levels. PMID:24686940

  13. Phytochemical investigation of natural and in vitro raised Vṛddhadāruka plants

    PubMed Central

    Bharati, Asha Jyoti; Bansal, Yogendra Kumar

    2014-01-01

    Background: Argyreia nervosa commonly known as elephant creeper (English) and Vṛddhadāruka (Sanskrit) is a woody climber that belongs to the family Convolvulaceae. Seeds of this plant contain hallucinogens including ergot alkaloids and a naturally occurring lysergic acid amide. Traditionally the plant is used in the treatment of gonorrhea, strangury, chronic ulcers, diabetes, anemia and cerebral disorders. The plant is also used as appetitiser, brain tonic, cardiotonic, aphrodisiac. It possesses anti-inflammatory, immunomodulatory, antibacterial, antiviral and antifungal activities. Objective: To give an account of information on in vitro regeneration and phytochemical analysis of the plant. Materials and Methods: Nodal explants were selected for in vitro regeneration. Different aerial parts viz., seeds, natural and in vitro leaf, stem and callus were dried and extracted with different solvents and were subjected to various phytochemical analyses. Results: Different concentrations of 6-benzylaminopurine showed shoot and root initiation. The study of phytochemical screening of different extracts showed the presence of bioactive substances like flavonoids, alkaloids, terpenoids, etc. Conclusion: The study will provide an efficient in vitro protocol for micropropagation as an alternative method to conserve the plant and shows the presence of some important secondary metabolites in the nature grown and in vitro raised plants which can be useful for treatment of various diseases. PMID:25861141

  14. Development of a full scale selective oil agglomeration plant

    SciTech Connect

    Donnelly, J.C.; Cooney, B.; Hoare, I.; Waugh, B.; Robinson, R.

    1998-12-31

    A research and development program managed by Australian Mining Investments Limited (AMI) on behalf of an investment syndicate was conducted with the objective of improving the efficiency and economy of the Selective Oil Agglomeration Process (SOAP), and developing viable commercial sized operating plants. Fewer than half the coal preparation plants in Australia beneficiate fine coal by froth flotation, the only viable alternative to SOAP for the recovery of low ash, fine and ultra fine coal. Those plants without flotation generally dispose of the ultra fine material, approximately {minus}100{micro}m in size, as tailings to waste. In the majority of cases this ultra fine waste contains more than 50% relatively low ash coal of saleable quality. It is believed that this coal constitutes a loss of 8--10 million tonnes per annum and that the coal mining industry would welcome a recovery process which has low capital and operating costs and will function automatically with minimal operator attention. The authors carried out a comprehensive literature study of selective oil agglomeration in order to gain a full understanding of the process and to plan the research program. Extensive studies were then undertaken on oil dispersion in the water phase, formation of oil water emulsions with surfactants and the optimization of surfactant selection. Oil and emulsion properties were investigated including stability, viscosity, temperature, concentration of components, time of formation, and cost. This work was followed by characterization studies on coals from the Gunnedah Basin and agglomeration test work on these coals. These agglomeration studies were performed firstly at bench level and then by using a small, 200 kg/hr continuous process development unit. The results were sufficiently encouraging to justify the design and construction of a fully instrumented, PLC controlled, 2 tph pilot plant at Gunnedah Colliery Coal Preparation Plant. Extensive trials were carried out on

  15. Natural selection by pulsed predation: survival of the thickest.

    PubMed

    Bijleveld, Aller I; Twietmeyer, Sönke; Piechocki, Julia; van Gils, Jan A; Piersma, Theunis

    2015-07-01

    Selective predation can lead to natural selection in prey populations and may alleviate competition among surviving individuals. The processes of selection and competition can have substantial effects on prey population dynamics, but are rarely studied simultaneously. Moreover, field studies of predator-induced short-term selection pressures on prey populations are scarce. Here we report measurements of density dependence in body composition in a bivalve prey (edible cockle, Cerastoderma edule) during bouts of intense predation by an avian predator (Red Knot, Calidris canutus). We measured densities, patchiness, morphology, and body composition (shell and flesh mass) of cockles in a quasi-experimental setting, i.e., before and after predation in three similar plots of 1 ha each, two of which experienced predation, and one of which remained unvisited in the course of the short study period and served as a reference. An individual's shell and flesh mass declined with cockle density (negative density dependence). Before predation, cockles were patchily distributed. After predation, during which densities were reduced by 78% (from 232 to 50 cockles/m2), the patchiness was substantially reduced, i.e., the spatial distribution was homogenized. Red Knots selected juvenile cockles with an average length of 6.9 ± 1.0 mm (mean ± SD). Cockles surviving predation had heavier shells than before predation (an increase of 21.5 percentage points), but similar flesh masses. By contrast, in the reference plot shell mass did not differ statistically between initial and final sampling occasions, while flesh mass was larger (an increase of 13.2 percentage points). In this field study, we show that Red Knots imposed a strong selection pressure on cockles to grow fast with thick shells and little flesh mass, with selection gradients among the highest reported in the literature. PMID:26378316

  16. The Emergence of Physiology and Form: Natural Selection Revisited

    PubMed Central

    Torday, John S.

    2016-01-01

    Natural Selection describes how species have evolved differentially, but it is descriptive, non-mechanistic. What mechanisms does Nature use to accomplish this feat? One known way in which ancient natural forces affect development, phylogeny and physiology is through gravitational effects that have evolved as mechanotransduction, seen in the lung, kidney and bone, linking as molecular homologies to skin and brain. Tracing the ontogenetic and phylogenetic changes that have facilitated mechanotransduction identifies specific homologous cell-types and functional molecular markers for lung homeostasis that reveal how and why complex physiologic traits have evolved from the unicellular to the multicellular state. Such data are reinforced by their reverse-evolutionary patterns in chronic degenerative diseases. The physiologic responses of model organisms like Dictyostelium and yeast to gravity provide deep comparative molecular phenotypic homologies, revealing mammalian Target of Rapamycin (mTOR) as the final common pathway for vertical integration of vertebrate physiologic evolution; mTOR integrates calcium/lipid epistatic balance as both the proximate and ultimate positive selection pressure for vertebrate physiologic evolution. The commonality of all vertebrate structure-function relationships can be reduced to calcium/lipid homeostatic regulation as the fractal unit of vertebrate physiology, demonstrating the primacy of the unicellular state as the fundament of physiologic evolution. PMID:27534726

  17. Evolution of behavior by density-dependent natural selection

    SciTech Connect

    Pingzhong Guo; Mueller, L.D.; Ayala, F.J. )

    1991-12-01

    Theories of density-dependent natural selection predict that evolution should favor those genotypes with the highest per capita rates of population growth under the current density conditions. These theories are silent about the mechanisms that may give rise to these increases in density-dependent growth rates. The authors have observed the evolution of six populations of Drosophila melanogaster recently placed in crowded environments after nearly 200 generations at low-population density in the laboratory. After 25 generations in these crowded cultures all six populations showed the predicted increase in population growth rates at high-population density with the concomitant decrease in their growth rates at low densities. These changes in rates of population growth are accompanied by changes in the feeding and pupation behavior of the larvae: those populations that have evolve at high-population densities have higher feeding rates and are less likely to pupate on or near the food surface than populations maintained at low densities. A detailed understanding of the mechanisms by which populations evolve under density-dependent natural selection will provide a framework for understanding that nature of trade-offs in life history evolution.

  18. The Emergence of Physiology and Form: Natural Selection Revisited.

    PubMed

    Torday, John S

    2016-01-01

    Natural Selection describes how species have evolved differentially, but it is descriptive, non-mechanistic. What mechanisms does Nature use to accomplish this feat? One known way in which ancient natural forces affect development, phylogeny and physiology is through gravitational effects that have evolved as mechanotransduction, seen in the lung, kidney and bone, linking as molecular homologies to skin and brain. Tracing the ontogenetic and phylogenetic changes that have facilitated mechanotransduction identifies specific homologous cell-types and functional molecular markers for lung homeostasis that reveal how and why complex physiologic traits have evolved from the unicellular to the multicellular state. Such data are reinforced by their reverse-evolutionary patterns in chronic degenerative diseases. The physiologic responses of model organisms like Dictyostelium and yeast to gravity provide deep comparative molecular phenotypic homologies, revealing mammalian Target of Rapamycin (mTOR) as the final common pathway for vertical integration of vertebrate physiologic evolution; mTOR integrates calcium/lipid epistatic balance as both the proximate and ultimate positive selection pressure for vertebrate physiologic evolution. The commonality of all vertebrate structure-function relationships can be reduced to calcium/lipid homeostatic regulation as the fractal unit of vertebrate physiology, demonstrating the primacy of the unicellular state as the fundament of physiologic evolution. PMID:27534726

  19. Population thinking and natural selection in dual-inheritance theory.

    PubMed

    Houkes, Wybo

    2012-05-01

    A deflationary perspective on theories of cultural evolution, in particular dual-inheritance theory, has recently been proposed by Lewens. On this 'pop-culture' analysis, dual-inheritance theorists apply population thinking to cultural phenomena, without claiming that cultural items evolve by natural selection. This paper argues against this pop-culture analysis of dual-inheritance theory. First, it focuses on recent dual-inheritance models of specific patterns of cultural change. These models exemplify population thinking without a commitment to natural selection of cultural items. There are grounds, however, for doubting the added explanatory value of the models in their disciplinary context-and thus grounds for engaging in other potentially explanatory projects based on dual-inheritance theory. One such project is suggested by advocates of the theory. Some of the motivational narratives that they offer can be interpreted as setting up an adaptationist project with regard to cumulative change in cultural items. We develop this interpretation here. On it, dual-inheritance theory features two interrelated selection processes, one on the level of genetically inherited learning mechanisms, another on the level of the cultural items transmitted through these mechanisms. This interpretation identifies a need for further modelling efforts, but also offers scope for enhancing the explanatory power of dual-inheritance theory. PMID:22523438

  20. Natural Products Screening for the Identification of Selective Monoamine Oxidase-B Inhibitors

    PubMed Central

    Zarmouh, Najla O.; Messeha, Samia S.; Elshami, Faisel M.; Soliman, Karam F. A.

    2016-01-01

    Aims Monoamine oxidase-B inhibitors (MAO-BIs) are used for the initial therapy of Parkinson’s disease. Also, MAO-BIs have shown to be effective neuroprotective agents in several neurodegenerative diseases. However, some concerns exist regarding the long-term use of these compounds. Meanwhile, natural compounds showed potential MAO-B selective inhibitions. To date, few selective natural MAO-BIs have been identified. Therefore, the current study is designed to identify plants with potent and specific MAO-B inhibition. Study Design In this work, we utilized high throughput screening to evaluate the different plants ethanolic extract for their effectiveness to inhibit recombinant human (h)MAO-A and hMAO-B and to determine the relative selectivity of the top MAO-BI. Methodology Recombinant human isozymes were verified by Western blotting, and the 155 plants were screened. A continuous fluorometric screening assay was performed followed by two separate hMAO-A and hMAO-B microtiter screenings and IC50 determinations for the top extracts. Results In the screened plants, 9% of the extracts showed more than 1.5-fold relative inhibition of hMAO-B (RIB) and another 9% showed more than 1.5-fold relative inhibition of hMAO-A. The top extracts with the most potent RIBs were Psoralea corylifolia seeds, Phellodendron amurense bark, Glycyrrhiza uralensis roots, and Ferula assafoetida roots, with the highest RIB of 5.9-fold. Furthermore, extensive maceration of the promising extracts led to increase inhibitory effects with a preserved RIB as confirmed with luminescence assay. The top four extracts hMAO-BIs were equally potent (IC50= 1.3 to 3.8 μg/mL) with highly significant relative selectivities to inhibit hMAO-B (4.1- to 13.4-fold). Conclusion The obtained results indicate that Psoralea corylifolia seeds, Ferula assafoetida, Glycyrrhiza uralensis roots, and Phellodendron amurense ethanolic extracts have selective inhibitions for human MAO-B. Investigating these plant extracts as

  1. Cameroonian Medicinal Plants: Pharmacology and Derived Natural Products

    PubMed Central

    Kuete, Victor; Efferth, Thomas

    2010-01-01

    Many developing countries including Cameroon have mortality patterns that reflect high levels of infectious diseases and the risk of death during pregnancy and childbirth, in addition to cancers, cardiovascular diseases and chronic respiratory diseases that account for most deaths in the developed world. Several medicinal plants are used traditionally for their treatment. In this review, plants used in Cameroonian traditional medicine with evidence for the activities of their crude extracts and/or derived products have been discussed. A considerable number of plant extracts and isolated compounds possess significant antimicrobial, anti-parasitic including antimalarial, anti-proliferative, anti-inflammatory, anti-diabetes, and antioxidant effects. Most of the biologically active compounds belong to terpenoids, phenolics, and alkaloids. Terpenoids from Cameroonian plants showed best activities as anti-parasitic, but rather poor antimicrobial effects. The best antimicrobial, anti-proliferative, and antioxidant compounds were phenolics. In conclusion, many medicinal plants traditionally used in Cameroon to treat various ailments displayed good activities in vitro. This explains the endeavor of Cameroonian research institutes in drug discovery from indigenous medicinal plants. However, much work is still to be done to standardize methodologies and to study the mechanisms of action of isolated natural products. PMID:21833168

  2. Sexual and natural selection in the evolution of extended phenotypes: the use of green nesting material in starlings.

    PubMed

    Rubalcaba, J G; Polo, V; Maia, R; Rubenstein, D R; Veiga, J P

    2016-08-01

    Although sexual selection is typically considered the predominant force driving the evolution of ritualized sexual behaviours, natural selection may also play an important and often underappreciated role. The use of green aromatic plants among nesting birds has been interpreted as a component of extended phenotype that evolved either via natural selection due to potential sanitary functions or via sexual selection as a signal of male attractiveness. Here, we compared both hypotheses using comparative methods in starlings, a group where this behaviour is widespread. We found that the use of green plants was positively related to male-biased size dimorphism and that it was most likely to occur among cavity-nesting species. These results suggest that this behaviour is likely favoured by sexual selection, but also related to its sanitary use in response to higher parasite loads in cavities. We speculate that the use of green plants in starlings may be facilitated by cavity nesting and was subsequently co-opted as a sexual signal by males. Our results represent an example of how an extended phenotypic component of males becomes sexually selected by females. Thus, both natural selection and sexual selection are necessary to fully understand the evolution of ritualized behaviours involved in courtship. PMID:27168035

  3. On-plant selection and genetic analysis of European corn borer (Lepidoptera: Crambidae) behavioral traits: plant abandonment versus plant establishment.

    PubMed

    Rausch, Michael A; Kroemer, Jeremy A; Gassmann, Aaron J; Hellmich, Richard L

    2014-10-01

    Although some studies have investigated how insect behavior could influence resistance evolution to transgenic plants, none have determined if behavioral traits respond to selection pressure and how they may be inherited. We investigated plant establishment and abandonment traits for the European corn borer, Ostrinia nubilalisi (Hübner) (Lepidoptera: Crambidae), by conducting a laboratory selection experiment and quantifying patterns of gene expression. Egg masses with emerging larvae were placed on maize plants and silking individuals were collected every 15 min during a 4-h period to generate a plant abandonment (PA) colony. Plants were dissected 24-72 h later, and larvae were collected for a plant establishment colony. Selection of the PA colony showed an increased propensity to abandon the host plant by the third generation. The propensity for larvae to establish on the plants, however, did not show a significant response until the sixth generation. Quantitative real-time-polymerase chain reaction (qRT-PCR) was used to determine expression profiles for behavior associated genes (foraging and Onslmo). Egg samples from the two selected colonies and nonselected laboratory colony were collected at 0, 24, 48, 72, and 96 h after egg deposition, and first instars were sampled after exposure to maize tissue. Compared with the plant establishment and nonselected laboratory colonies at the 0-h time period, foraging and Onslmo showed higher expression in the PA colony. This is the first study that has specifically selected for these traits over several generations and analyzed behavior-associated genes to elucidate genetic changes. PMID:25203864

  4. The natural selection of fidelity in social learning

    PubMed Central

    Sperber, Dan

    2010-01-01

    Social learning mechanisms are usually assumed to explain both the spread and the persistence of cultural behavior. In a recent article, we showed that the fidelity of social learning commonly found in transmission chain experiments is not high enough to explain cultural stability. Here we want to both enrich and qualify this conclusion by looking at the case of song transmission in song birds, which can be faithful to the point of being true replication. We argue that this high fidelity results from natural selection pressure on cognitive mechanisms. This observation strengthens our main argument. Social learning mechanisms are unlikely to be faithful enough to explain cultural stability because they are generally selected not for high fidelity but for generalization and adjustment to the individual’s needs, capacities and situation. PMID:20798823

  5. Kaon condensation, black holes, and cosmological natural selection.

    PubMed

    Brown, G E; Lee, Chang-Hwan; Rho, Mannque

    2008-08-29

    It is argued that a well-measured double neutron-star binary in which the two neutron stars are more than 4% different from each other in mass or a massive neutron star with mass M > or approximately 2M(middle dot in circle) would put in serious doubt or simply falsify the following chain of predictions: (1) a nearly vanishing vector meson mass at chiral restoration, (2) kaon condensation at a density n-3n0, (3) the Brown-Bethe maximum neutron-star mass Mmax approximately 1.5M(middle dot in circle), and (4) Smolin's "cosmological natural selection" hypothesis. PMID:18851598

  6. Programed Death is Favored by Natural Selection in Spatial Systems.

    PubMed

    Werfel, Justin; Ingber, Donald E; Bar-Yam, Yaneer

    2015-06-12

    Standard evolutionary theories of aging and mortality, implicitly based on mean-field assumptions, hold that programed mortality is untenable, as it opposes direct individual benefit. We show that in spatial models with local reproduction, programed deaths instead robustly result in long-term benefit to a lineage, by reducing local environmental resource depletion via spatiotemporal patterns causing feedback over many generations. Results are robust to model variations, implying that direct selection for shorter life span may be quite widespread in nature. PMID:26196833

  7. Alkene Metathesis and Renewable Materials: Selective Transformations of Plant Oils

    NASA Astrophysics Data System (ADS)

    Malacea, Raluca; Dixneuf, Pierre H.

    The olefin metathesis of natural oils and fats and their derivatives is the basis of clean catalytic reactions relevant to green chemistry processes and the production of generate useful chemicals from renewable raw materials. Three variants of alkene metathesis: self-metathesis, ethenolysis and cross-metathesis applied to plant oil derivatives will show new routes to fine chemicals, bifunctional products, polymer precursours and industry intermediates.

  8. Positive selection driving diversification in plant secondary metabolism

    PubMed Central

    Benderoth, Markus; Textor, Susanne; Windsor, Aaron J.; Mitchell-Olds, Thomas; Gershenzon, Jonathan; Kroymann, Juergen

    2006-01-01

    In Arabidopsis thaliana and related plants, glucosinolates are a major component in the blend of secondary metabolites and contribute to resistance against herbivorous insects. Methylthioalkylmalate synthases (MAM) encoded at the MAM gene cluster control an early step in the biosynthesis of glucosinolates and, therefore, are central to the diversification of glucosinolate metabolism. We sequenced bacterial artificial chromosomes containing the MAM cluster from several Arabidopsis relatives, conducted enzyme assays with heterologously expressed MAM genes, and analyzed MAM nucleotide variation patterns. Our results show that gene duplication, neofunctionalization, and positive selection provide the mechanism for biochemical adaptation in plant defense. These processes occur repeatedly in the history of the MAM gene family, indicating their fundamental importance for the evolution of plant metabolic diversity both within and among species. PMID:16754868

  9. Combinatorially selected defense peptides protect plant roots from pathogen infection

    PubMed Central

    Fang, Zhiwei David; Laskey, James G.; Huang, Shaoxing; Bilyeu, Kristin D.; Morris, Roy O.; Schmidt, Francis J.; English, James T.

    2006-01-01

    Agricultural productivity and sustainability are continually challenged by emerging and indigenous pathogens. Currently, many pathogens can be combated only with biocides or environmentally dangerous fumigants. Here, we report a rapid and pathogen-specific strategy to reduce infection by organisms that target plant roots. Combinatorially selected defense peptides, previously shown to effect premature encystment of Phytophthora capsici zoospores, were fused to maize cytokinin oxidase/dehydrogenase as a display scaffold. When expressed in tomato roots, the peptide-scaffold constructs were secreted and accumulated to sufficient concentrations in the rhizosphere to induce zoospore encystment and thereby deter taxis to the root surface. Pathogen infection was significantly inhibited in roots expressing bioactive peptides fused to the maize cytokinin oxidase/dehydrogenase scaffold. This peptide-delivery technology is broadly applicable for rapid development of plant defense attributes against plant pathogens. PMID:17030803

  10. Effects of Mode of Target Task Selection on Learning about Plants in a Mobile Learning Environment: Effortful Manual Selection versus Effortless QR-Code Selection

    ERIC Educational Resources Information Center

    Gao, Yuan; Liu, Tzu-Chien; Paas, Fred

    2016-01-01

    This study compared the effects of effortless selection of target plants using quick respond (QR) code technology to effortful manual search and selection of target plants on learning about plants in a mobile device supported learning environment. In addition, it was investigated whether the effectiveness of the 2 selection methods was…

  11. The physiological effects of selection in rainbow trout selected for growth on plant-based feeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been proven that rainbow trout can selectively be improved to more efficiently process and utilize nutrients from different sources. A stock of rainbow trout has been developed to grow faster on a diet formulated without fishmeal and the protein sources coming completely from plant material. ...

  12. [Plants as a source of natural harmful substances].

    PubMed

    Czerwiecki, Ludwik

    2005-01-01

    In this review the several data concerning phytotoxins as natural harmful substances of plants and phycotoxins--toxicants of algae were described. For example plants are source of pyrrolizidine alkaloids, glycoalkaloids, glucosinolates as well as glycosides, saponine and psolarens. Possible adverse effects of phytoestrogens as endocrine disruptors versus beneficial influence these substances on human organism were mentioned. About lectins as possible factors of some diseases was reported, as well as some proteins as allergens of soy and peanuts was mentioned. Accumulated by shellfish and fish the most important phycotoxins such as saxitoxin, okadaic acid, brevetoxins and ciguatoxins were described. Phycotoxins produced several poisoning symptoms. Microcystins and nodularin--cyanobacterial phycotoxins of freshwater, was mentioned. In conclusion, the need of limitation of permissible levels of some plant toxicants, development of analytical methods as well as knowledge of influence of some technological processes on toxic plant substances was highlighted. The importance of balanced diet as a tool of defense against plant toxicants was concluded. PMID:16433227

  13. Insect herbivores selectively mute GLV production in plants.

    PubMed

    Savchenko, Tatyana; Dehesh, Katayoon

    2013-05-01

    Through co-evolution insect herbivores have developed a myriad of strategies to manipulate host plant defense responses that include the synthesis of defensive compounds whose composition depends on the insect feeding mode.  Among the plant-produced compounds are jasmonates (JAs), and Green Leafy Volatiles (GLVs), metabolites produced by the two parallel and competing branches of the oxylipin pathway. Here we provide evidence that chewing insects stimulate JA production but suppress the synthesis of GLVs through the transcriptional and post transcriptional reprogramming of critical genes in the corresponding pathway. We further establish that herbivore-derived elicitors known as Herbivore-Associated Molecular Patterns (HAMPs) are responsible for the reprogramming of these pathway genes. Through this strategy chewing herbivores coerce the plant signaling machinery that would otherwise leads to a reduction in the nutritional quality of the immediate and neighboring plants, and additionally shelters the herbivores from their natural enemies that are otherwise guided by the GLV cues to prey-infested plants.  PMID:23470722

  14. In vitro cytotoxic screening of selected Saudi medicinal plants.

    PubMed

    Almehdar, Hussein; Abdallah, Hossam M; Osman, Abdel-Moneim M; Abdel-Sattar, Essam A

    2012-04-01

    Many natural products from plants have been identified to exert anticancer activity. It might be expected to be a challenge to look at the Saudi plants in order to discover new sources for new molecules which may have anticancer activity. The methanolic extracts of forty species of plants traditionally used in Saudi Arabia for the treatment of a variety of diseases were tested in vitro for their potential anticancer activity on different human cancer cell lines. The cytotoxic activity of the methanolic extracts of the tested plants were determined using three human cancer cell lines, namely, breast cancer (MCF7), hepatocellular carcinoma (HEPG2), and cervix cancer (HELA) cells. In addition, human normal melanocyte (HFB4) was used as normal nonmalignant cells. Sulforhodamine B colorimetric assay was used to evaluate the in vitro cytotoxic activity of the different extracts. The growth inhibition of 50% (IC(50)) for each extract was calculated from the optical density of treated and untreated cells. Doxorubicin, a broad-spectrum anticancer drug, was used as the positive control. Nine plant extracts were chosen for further fractionation based on their activity and availability. Interesting cytotoxic activity was observed for Hypoestes forskaolii, Withania somnifera, Solanum glabratum, Adenium obesum, Pistacia vera oleoresin, Caralluma quadrangula, Eulophia petersii, Phragmanthera austroarabica, and Asparagus officinalis. Other extracts showed poor activity. PMID:21953271

  15. Chalcone-based Selective Inhibitors of a C4 Plant Key Enzyme as Novel Potential Herbicides.

    PubMed

    Nguyen, G T T; Erlenkamp, G; Jäck, O; Küberl, A; Bott, M; Fiorani, F; Gohlke, H; Groth, G

    2016-01-01

    Weeds are a challenge for global food production due to their rapidly evolving resistance against herbicides. We have identified chalcones as selective inhibitors of phosphoenolpyruvate carboxylase (PEPC), a key enzyme for carbon fixation and biomass increase in the C4 photosynthetic pathway of many of the world's most damaging weeds. In contrast, many of the most important crop plants use C3 photosynthesis. Here, we show that 2',3',4',3,4-Pentahydroxychalcone (IC50 = 600 nM) and 2',3',4'-Trihydroxychalcone (IC50 = 4.2 μM) are potent inhibitors of C4 PEPC but do not affect C3 PEPC at a same concentration range (selectivity factor: 15-45). Binding and modeling studies indicate that the active compounds bind at the same site as malate/aspartate, the natural feedback inhibitors of the C4 pathway. At the whole plant level, both substances showed pronounced growth-inhibitory effects on the C4 weed Amaranthus retroflexus, while there were no measurable effects on oilseed rape, a C3 plant. Growth of selected soil bacteria was not affected by these substances. Our chalcone compounds are the most potent and selective C4 PEPC inhibitors known to date. They offer a novel approach to combat C4 weeds based on a hitherto unexplored mode of allosteric inhibition of a C4 plant key enzyme. PMID:27263468

  16. Chalcone-based Selective Inhibitors of a C4 Plant Key Enzyme as Novel Potential Herbicides

    PubMed Central

    Nguyen, G. T. T.; Erlenkamp, G.; Jäck, O.; Küberl, A.; Bott, M.; Fiorani, F.; Gohlke, H.; Groth, G.

    2016-01-01

    Weeds are a challenge for global food production due to their rapidly evolving resistance against herbicides. We have identified chalcones as selective inhibitors of phosphoenolpyruvate carboxylase (PEPC), a key enzyme for carbon fixation and biomass increase in the C4 photosynthetic pathway of many of the world’s most damaging weeds. In contrast, many of the most important crop plants use C3 photosynthesis. Here, we show that 2′,3′,4′,3,4-Pentahydroxychalcone (IC50 = 600 nM) and 2′,3′,4′-Trihydroxychalcone (IC50 = 4.2 μM) are potent inhibitors of C4 PEPC but do not affect C3 PEPC at a same concentration range (selectivity factor: 15–45). Binding and modeling studies indicate that the active compounds bind at the same site as malate/aspartate, the natural feedback inhibitors of the C4 pathway. At the whole plant level, both substances showed pronounced growth-inhibitory effects on the C4 weed Amaranthus retroflexus, while there were no measurable effects on oilseed rape, a C3 plant. Growth of selected soil bacteria was not affected by these substances. Our chalcone compounds are the most potent and selective C4 PEPC inhibitors known to date. They offer a novel approach to combat C4 weeds based on a hitherto unexplored mode of allosteric inhibition of a C4 plant key enzyme. PMID:27263468

  17. Chalcone-based Selective Inhibitors of a C4 Plant Key Enzyme as Novel Potential Herbicides

    NASA Astrophysics Data System (ADS)

    Nguyen, G. T. T.; Erlenkamp, G.; Jäck, O.; Küberl, A.; Bott, M.; Fiorani, F.; Gohlke, H.; Groth, G.

    2016-06-01

    Weeds are a challenge for global food production due to their rapidly evolving resistance against herbicides. We have identified chalcones as selective inhibitors of phosphoenolpyruvate carboxylase (PEPC), a key enzyme for carbon fixation and biomass increase in the C4 photosynthetic pathway of many of the world’s most damaging weeds. In contrast, many of the most important crop plants use C3 photosynthesis. Here, we show that 2‧,3‧,4‧,3,4-Pentahydroxychalcone (IC50 = 600 nM) and 2‧,3‧,4‧-Trihydroxychalcone (IC50 = 4.2 μM) are potent inhibitors of C4 PEPC but do not affect C3 PEPC at a same concentration range (selectivity factor: 15–45). Binding and modeling studies indicate that the active compounds bind at the same site as malate/aspartate, the natural feedback inhibitors of the C4 pathway. At the whole plant level, both substances showed pronounced growth-inhibitory effects on the C4 weed Amaranthus retroflexus, while there were no measurable effects on oilseed rape, a C3 plant. Growth of selected soil bacteria was not affected by these substances. Our chalcone compounds are the most potent and selective C4 PEPC inhibitors known to date. They offer a novel approach to combat C4 weeds based on a hitherto unexplored mode of allosteric inhibition of a C4 plant key enzyme.

  18. Bayesian Inference of Natural Selection from Allele Frequency Time Series.

    PubMed

    Schraiber, Joshua G; Evans, Steven N; Slatkin, Montgomery

    2016-05-01

    The advent of accessible ancient DNA technology now allows the direct ascertainment of allele frequencies in ancestral populations, thereby enabling the use of allele frequency time series to detect and estimate natural selection. Such direct observations of allele frequency dynamics are expected to be more powerful than inferences made using patterns of linked neutral variation obtained from modern individuals. We developed a Bayesian method to make use of allele frequency time series data and infer the parameters of general diploid selection, along with allele age, in nonequilibrium populations. We introduce a novel path augmentation approach, in which we use Markov chain Monte Carlo to integrate over the space of allele frequency trajectories consistent with the observed data. Using simulations, we show that this approach has good power to estimate selection coefficients and allele age. Moreover, when applying our approach to data on horse coat color, we find that ignoring a relevant demographic history can significantly bias the results of inference. Our approach is made available in a C++ software package. PMID:27010022

  19. Phylogenomic analysis of natural selection pressure in Streptococcus genomes

    PubMed Central

    Anisimova, Maria; Bielawski, Joseph; Dunn, Katherine; Yang, Ziheng

    2007-01-01

    Background In comparative analyses of bacterial pathogens, it has been common practice to discriminate between two types of genes: (i) those shared by pathogens and their non-pathogenic relatives (core genes), and (ii) those found exclusively in pathogens (pathogen-specific accessory genes). Rather than attempting to a priori delineate genes into sets more or less relevant to pathogenicity, we took a broad approach to the analysis of Streptococcus species by investigating the strength of natural selection in all clusters of homologous genes. The genus Streptococcus is comprised of a wide variety of both pathogenic and commensal lineages, and we relate our findings to the pre-existing knowledge of Streptococcus virulence factors. Results Our analysis of 1730 gene clusters revealed 136 cases of positive Darwinian selection, which we suggest is most likely to result from an antagonistic interaction between the host and pathogen at the molecular level. A two-step validation procedure suggests that positive selection was robustly identified in our genomic survey. We found no evidence to support the notion that pathogen specific accessory genes are more likely to be subject to positive selection than core genes. Indeed, we even uncovered a few cases of essential gene evolution by positive selection. Among the gene clusters subject to positive selection, a large fraction (29%) can be connected to virulence. The most striking finding was that a considerable fraction of the positively selected genes are also known to have tissue specific patterns of expression during invasive disease. As current expression data is far from comprehensive, we suggest that this fraction was underestimated. Conclusion Our findings suggest that pathogen specific genes, although a popular focus of research, do not provide a complete picture of the evolutionary dynamics of virulence. The results of this study, and others, support the notion that the products of both core and accessory genes

  20. 8-year field comparison of naturally seeded to planted container `pinus taeda`, with and without release

    SciTech Connect

    Cain, M.D.; Barnett, J.P.

    1996-01-09

    A field study compared genetically improved, container loblolly pines (Pinus taedo L.) with naturally seeded loblolly pines through eight growing seasons on a cutover site in southern Arkansas, U.S.A. Measurement pines on 6 of 12 plots were released from woody and herbaceous competition within a 61-cm radius of each tree stem. On natural pine plots, only 1st-year pine seedlings were selected for measurement based on quality standards and their spacing. Woody competition was controlled by hand cutting for 5 consecutive years, and herbaceous competition was controlled with herbicides for 4 consecutive years. Release treatments increased 8-year survival by 50% for natural pines and by 35% for planted pines. Greater gains (343-391%) in individual tree volumes were achieved within regeneration techniques, as a result of release, than were achieved with the two regeneration techniques. In addition, stand volume gains of 647% and 910% were achieved by planted and natural pines, respectively, as a result of release. Eight years after field establishment, stand volume index averaged 46% higher on planted plots than on natural plots. Degree of overtopping was a better predictor of pine performance than live-crown ratio.

  1. PlantNATsDB: a comprehensive database of plant natural antisense transcripts

    PubMed Central

    Chen, Dijun; Yuan, Chunhui; Zhang, Jian; Zhang, Zhao; Bai, Lin; Meng, Yijun; Chen, Ling-Ling; Chen, Ming

    2012-01-01

    Natural antisense transcripts (NATs), as one type of regulatory RNAs, occur prevalently in plant genomes and play significant roles in physiological and pathological processes. Although their important biological functions have been reported widely, a comprehensive database is lacking up to now. Consequently, we constructed a plant NAT database (PlantNATsDB) involving approximately 2 million NAT pairs in 69 plant species. GO annotation and high-throughput small RNA sequencing data currently available were integrated to investigate the biological function of NATs. PlantNATsDB provides various user-friendly web interfaces to facilitate the presentation of NATs and an integrated, graphical network browser to display the complex networks formed by different NATs. Moreover, a ‘Gene Set Analysis’ module based on GO annotation was designed to dig out the statistical significantly overrepresented GO categories from the specific NAT network. PlantNATsDB is currently the most comprehensive resource of NATs in the plant kingdom, which can serve as a reference database to investigate the regulatory function of NATs. The PlantNATsDB is freely available at http://bis.zju.edu.cn/pnatdb/. PMID:22058132

  2. Seed Predators, not Herbivores, Exert Natural Selection on Solidago spp. in an Urban Archipelago.

    PubMed

    Bode, R F; Gilbert, A B

    2016-02-01

    The effects of urbanization on biodiversity are well established, as a growing city will reduce the size and diversity of patches of native plants. Recolonization of old patches and discovery of new ones by arthropod herbivores should occur as predicted by island biogeography theory. Although colonization represents an increase in biodiversity, such arrivals may exert new forms of natural selection on plants through herbivory and seed predation. Using a single species of old-field aster (Solidago altissima L.), we found that the level of natural selection by seed predators and herbivores follows patterns of island biogeography, with lower amounts of damage on smaller islands, where there are fewer species, and hypothetically smaller populations of arthropods. We also found that in an urban system, levels of herbivory are far below the tolerance levels of Solidago, and that seed predators are likely to be the only arthropod to cause reduced fitness. The pattern seen also implies that as a patch of Solidago grows through clonal expansion, it will come under higher selective pressure. PMID:26494854

  3. Sargassum as a Natural Solution to Enhance Dune Plant Growth

    NASA Astrophysics Data System (ADS)

    Williams, Amy; Feagin, Rusty

    2010-11-01

    Many beach management practices focus on creating an attractive environment for tourists, but can detrimentally affect long-term dune integrity. One such practice is mechanical beach raking in which the wrack line is removed from the beach front. In Texas, Sargassum fluitans and natans, types of brown alga, are the main components of wrack and may provide a subsidy to the ecosystem. In this study, we used greenhouse studies to test the hypothesis that the addition of sargassum can increase soil nutrients and produce increased growth in dune plants. We also conducted an analysis of the nutrients in the sargassum to determine the mechanisms responsible for any growth enhancement. Panicum amarum showed significant enhancement of growth with the addition of sargassum, and while Helianthus debilis, Ipomoea stolonifera, Sporobolus virginicus, and Uniola paniculata responded slightly differently to the specific treatments, none were impaired by the addition of sargassum. In general, plants seemed to respond well to unwashed sargassum and multiple additions of sargassum, indicating that plants may have adapted to capitalize on the subsidy in its natural state directly from the ocean. For coastal managers, the use of sargassum as a fertilizer could be a positive, natural, and efficient method of dealing with the accumulation of wrack on the beach.

  4. Commercial ballard PEM fuel cell natural gas power plant development

    SciTech Connect

    Watkins, D.S.; Dunnison, D.; Cohen, R.

    1996-12-31

    The electric utility industry is in a period of rapid change. Deregulation, wholesale and retail wheeling, and corporate restructuring are forcing utilities to adopt new techniques for conducting their business. The advent of a more customer oriented service business with tailored solutions addressing such needs as power quality is a certain product of the deregulation of the electric utility industry. Distributed and dispersed power are fundamental requirements for such tailored solutions. Because of their modularity, efficiency and environmental benefits, fuel cells are a favored solution to implement distributed and dispersed power concepts. Ballard Power Systems has been working to develop and commercialize Proton Exchange Membrane (PEM) fuel cell power plants for stationary power markets. PEM`s capabilities of flexible operation and multiple market platforms bodes well for success in the stationary power market. Ballard`s stationary commercialization program is now in its second phase. The construction and successful operation of a 10 kW natural gas fueled, proof-of-concept power plant marked the completion of phase one. In the second phase, we are developing a 250 kW market entry power plant. This paper discusses Ballard`s power plant development plan philosophy, the benefits from this approach, and our current status.

  5. Selective Behaviour of Honeybees in Acquiring European Propolis Plant Precursors.

    PubMed

    Isidorov, Valery A; Bakier, Sławomir; Pirożnikow, Ewa; Zambrzycka, Monika; Swiecicka, Izabela

    2016-06-01

    Honey bees harvest resins from various plant species and use them in the hive as propolis. While there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. The main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. Samples of propolis originating from temperate zones of Europe and the supposed botanical precursors of the product were analyzed. Taxonomical markers of bud resins of two white birch species, aspen, black poplar, horse-chestnut, black alder, and Scots pine were determined through GC-MS analysis. All these trees have been reported as sources of propolis, but comparisons of the chemical composition of their bud resins with the compositions of propolis samples from seven European countries have demonstrated the presence of taxonomical markers only from black poplar, aspen, and one species of birch. This suggests selective behavior during the collection of bud resins by honeybees. To examine the causes of such selectivity, the antimicrobial properties of bud resins were determined. Horse-chestnut resins had lower antimicrobial activity than the other resins which did not differ significantly. PMID:27294416

  6. Design and operation of a selective sweetening plant using MDEA

    SciTech Connect

    MacKenzie, D.H.; Chiraka-Parambil, F.; Daniels, C.A.; Bullin, J.A.

    1986-01-01

    The Signalta Resources Forestburg Gas Plant was constructed during the winter of 1983 and placed on stream in April of 1984. A design outlet gas specification of 1/4 grain H/sub 2/S/100 scf was requested to ensure meeting the contract commitment of 1 grain/100 scf. The design gas flowrate was 30 MMSCFD containing 0.5% H/sub 2/S and 3% CO/sub 2/ at 415 psia and 70/sup 0/F. The overall plant is configured as shown in Figure 1. Inlet separation facilities are followed by a feed gas heater. The gas stream then flows through a filter separator followed by the amine contactor. Another filter separator is used as a sweet gas scrubber. After sweetening, the gas is routed to a dew point control refrigeration unit. Finally, a single stage of compression is required to boost the gas to 1200 psig maximum pipeline pressure. The sweetening chemical selected for the Forestburg Plant was methyldiethanolamine (MDEA). This was chosen due to its capability to remove H/sub 2/S and leave a portion of the CO/sub 2/ in the residue gas. At the time of plant commissioning it was one of the first operating MDEA facilities in Western Canada.

  7. Natural and sexual selection in a wild insect population.

    PubMed

    Rodríguez-Muñoz, R; Bretman, A; Slate, J; Walling, C A; Tregenza, T

    2010-06-01

    The understanding of natural and sexual selection requires both field and laboratory studies to exploit the advantages and avoid the disadvantages of each approach. However, studies have tended to be polarized among the types of organisms studied, with vertebrates studied in the field and invertebrates in the lab. We used video monitoring combined with DNA profiling of all of the members of a wild population of field crickets across two generations to capture the factors predicting the reproductive success of males and females. The factors that predict a male's success in gaining mates differ from those that predict how many offspring he has. We confirm the fundamental prediction that males vary more in their reproductive success than females, and we find that females as well as males leave more offspring when they mate with more partners. PMID:20522773

  8. Contemporary evolution during invasion: evidence for differentiation, natural selection, and local adaptation.

    PubMed

    Colautti, Robert I; Lau, Jennifer A

    2015-05-01

    Biological invasions are 'natural' experiments that can improve our understanding of contemporary evolution. We evaluate evidence for population differentiation, natural selection and adaptive evolution of invading plants and animals at two nested spatial scales: (i) among introduced populations (ii) between native and introduced genotypes. Evolution during invasion is frequently inferred, but rarely confirmed as adaptive. In common garden studies, quantitative trait differentiation is only marginally lower (~3.5%) among introduced relative to native populations, despite genetic bottlenecks and shorter timescales (i.e. millennia vs. decades). However, differentiation between genotypes from the native vs. introduced range is less clear and confounded by nonrandom geographic sampling; simulations suggest this causes a high false-positive discovery rate (>50%) in geographically structured populations. Selection differentials (¦s¦) are stronger in introduced than in native species, although selection gradients (¦β¦) are not, consistent with introduced species experiencing weaker genetic constraints. This could facilitate rapid adaptation, but evidence is limited. For example, rapid phenotypic evolution often manifests as geographical clines, but simulations demonstrate that nonadaptive trait clines can evolve frequently during colonization (~two-thirds of simulations). Additionally, QST-FST studies may often misrepresent the strength and form of natural selection acting during invasion. Instead, classic approaches in evolutionary ecology (e.g. selection analysis, reciprocal transplant, artificial selection) are necessary to determine the frequency of adaptive evolution during invasion and its influence on establishment, spread and impact of invasive species. These studies are rare but crucial for managing biological invasions in the context of global change. PMID:25891044

  9. More than Meets the Eye--a Simulation of Natural Selection.

    ERIC Educational Resources Information Center

    Allen, J. A.; And Others

    1987-01-01

    Presents experiments using wild birds as predators and pastry as prey and colored stones as background to demonstrate natural selection. Describes the exercise as an exercise in simulating natural selection. (Author/CW)

  10. A below-ground herbivore shapes root defensive chemistry in natural plant populations.

    PubMed

    Huber, Meret; Bont, Zoe; Fricke, Julia; Brillatz, Théo; Aziz, Zohra; Gershenzon, Jonathan; Erb, Matthias

    2016-03-30

    Plants display extensive intraspecific variation in secondary metabolites. However, the selective forces shaping this diversity remain often unknown, especially below ground. Using Taraxacum officinale and its major native insect root herbivore Melolontha melolontha, we tested whether below-ground herbivores drive intraspecific variation in root secondary metabolites. We found that high M. melolontha infestation levels over recent decades are associated with high concentrations of major root latex secondary metabolites across 21 central European T. officinale field populations. By cultivating offspring of these populations, we show that both heritable variation and phenotypic plasticity contribute to the observed differences. Furthermore, we demonstrate that the production of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) is costly in the absence, but beneficial in the presence of M. melolontha, resulting in divergent selection of TA-G. Our results highlight the role of soil-dwelling insects for the evolution of plant defences in nature. PMID:27009228

  11. Selective phonotaxis of female crickets under natural outdoor conditions.

    PubMed

    Hirtenlehner, Stefan; Römer, Heiner

    2014-03-01

    Acoustic mate choice in insects has been extensively studied under laboratory conditions, using different behavioural paradigms. Ideally, however, mate choice designs should reflect natural conditions, including the physical properties of the transmission channel for the signal. Since little is known about the discrimination ability of females between male song variants under natural conditions, we performed phonotaxis experiments with female field crickets (Gryllus bimaculatus) outdoors, using two-choice decisions based on differences in carrier frequency, sound pressure level, and chirp rate. For all three song parameters, minimum differences necessary for a significant preference between two song models were considerably larger outdoors compared to laboratory conditions. A minimum amplitude difference of 5 dB was required for a significant choice in the field, compared to only 1-2 dB reported for lab-based experiments. Due to the tuned receiver system, differences in carrier frequency equal differences in perceived loudness, and the results on choice for differences in carrier frequency corroborate those in amplitude. Similarly, chirp rate differences of 50 chirps/min were required outdoors compared to only 20 chirps/min in the lab. For predictions about patterns of sexual selection, future studies need to consider the different outcomes of mate choice decisions in lab and field trials. PMID:24488017

  12. Natural selection and self-organization in complex adaptive systems.

    PubMed

    Di Bernardo, Mirko

    2010-01-01

    The central theme of this work is self-organization "interpreted" both from the point of view of theoretical biology, and from a philosophical point of view. By analysing, on the one hand, those which are now considered--not only in the field of physics--some of the most important discoveries, that is complex systems and deterministic chaos and, on the other hand, the new frontiers of systemic biology, this work highlights how large thermodynamic systems which are open can spontaneously stay in an orderly regime. Such systems can represent the natural source of the order required for a stable self-organization, for homoeostasis and for hereditary variations. The order, emerging in enormous randomly interconnected nets of binary variables, is almost certainly only the precursor of similar orders emerging in all the varieties of complex systems. Hence, this work, by finding new foundations for the order pervading the living world, advances the daring hypothesis according to which Darwinian natural selection is not the only source of order in the biosphere. Thus, the article, by examining the passage from Prigogine's dissipative structures theory to the contemporary theory of biological complexity, highlights the development of a coherent and continuous line of research which is set to individuate the general principles marking the profound reality of that mysterious self-organization characterizing the complexity of life. PMID:20882479

  13. Formal reasoning ability and misconceptions concerning genetics and natural selection

    NASA Astrophysics Data System (ADS)

    Lawson, Anton E.; Thompson, Lois D.

    Students often hold misconceptions about natural phenomena. To overcome misconceptions students must become aware of the scientific conceptions, the evidence that bears on the validity of their misconceptions and the scientific conceptions, and they must be able to generate the logical relationships among the evidence and alternative conceptions. Because formal operational reasoning patterns are necessary to generate these logical relationships, it was predicted that, following instruction, formal operational students would hold significantly fewer misconceptions than their concrete operational classmates. To test this hypothesis 131 seventh-grade students were administered an essay test on principles of genetics and natural selection following instruction. Responses were categorized in terms of the number of misconceptions present. The number of misconceptions was compared to reasoning ability (concrete, transitional, formal), mental capacity (<6, 6, 7), verbal intelligence (low, medium, high), and cognitive style (field dependent, intermediate, field independent). The only student variable consistently and significantly related to the number of misconceptions was reasoning ability; thus, support for the major hypothesis of the study was obtained.

  14. Spatially-Correlated Risk in Nature Reserve Site Selection.

    PubMed

    Albers, Heidi J; Busby, Gwenlyn M; Hamaide, Bertrand; Ando, Amy W; Polasky, Stephen

    2016-01-01

    Establishing nature reserves protects species from land cover conversion and the resulting loss of habitat. Even within a reserve, however, many factors such as fires and defoliating insects still threaten habitat and the survival of species. To address the risk to species survival after reserve establishment, reserve networks can be created that allow some redundancy of species coverage to maximize the expected number of species that survive in the presence of threats. In some regions, however, the threats to species within a reserve may be spatially correlated. As examples, fires, diseases, and pest infestations can spread from a starting point and threaten neighboring parcels' habitats, in addition to damage caused at the initial location. This paper develops a reserve site selection optimization framework that compares the optimal reserve networks in cases where risks do and do not reflect spatial correlation. By exploring the impact of spatially-correlated risk on reserve networks on a stylized landscape and on an Oregon landscape, this analysis demonstrates an appropriate and feasible method for incorporating such post-reserve establishment risks in the reserve site selection literature as an additional tool to be further developed for future conservation planning. PMID:26789127

  15. Spatially-Correlated Risk in Nature Reserve Site Selection

    PubMed Central

    Albers, Heidi J.; Busby, Gwenlyn M.; Hamaide, Bertrand; Ando, Amy W.; Polasky, Stephen

    2016-01-01

    Establishing nature reserves protects species from land cover conversion and the resulting loss of habitat. Even within a reserve, however, many factors such as fires and defoliating insects still threaten habitat and the survival of species. To address the risk to species survival after reserve establishment, reserve networks can be created that allow some redundancy of species coverage to maximize the expected number of species that survive in the presence of threats. In some regions, however, the threats to species within a reserve may be spatially correlated. As examples, fires, diseases, and pest infestations can spread from a starting point and threaten neighboring parcels’ habitats, in addition to damage caused at the initial location. This paper develops a reserve site selection optimization framework that compares the optimal reserve networks in cases where risks do and do not reflect spatial correlation. By exploring the impact of spatially-correlated risk on reserve networks on a stylized landscape and on an Oregon landscape, this analysis demonstrates an appropriate and feasible method for incorporating such post-reserve establishment risks in the reserve site selection literature as an additional tool to be further developed for future conservation planning. PMID:26789127

  16. Thermodynamics of natural selection II: Chemical Carnot cycles.

    PubMed

    Smith, Eric

    2008-05-21

    This is the second in a series of three papers devoted to energy flow and entropy changes in chemical and biological processes, and to their relations to the thermodynamics of computation. In the first paper of the series, it was shown that a general-form dimensional argument from the second law of thermodynamics captures a number of scaling relations governing growth and development across many domains of life. It was also argued that models of physiology based on reversible transformations provide sensible approximations within which the second-law scaling is realized. This paper provides a formal basis for decomposing general cyclic, fixed-temperature chemical reactions, in terms of the chemical equivalent of Carnot's cycle for heat engines. It is shown that the second law relates the minimal chemical work required to perform a cycle to the Kullback-Leibler divergence produced in its chemical output ensemble from that of a Gibbs equilibrium. Reversible models of physiology are used to create reversible models of natural selection, which relate metabolic energy requirements to information gain under optimal conditions. When dissipation is added to models of selection, the second-law constraint is generalized to a relation between metabolic work and the combined energies of growth and maintenance. PMID:18367209

  17. Mosquito management in the face of natural selection.

    PubMed

    Agusto, Folashade B; Bewick, Sharon; Parshad, Rana D

    2012-09-01

    The sterile insect technique (SIT) is an appealing method for managing mosquito populations while avoiding the environmental and social costs associated with more traditional control strategies like insecticide application. Success of SIT, however, hinges on sterile males being able to compete for females. As a result, heavy and/or continued use of SIT could potentially diminish its efficacy if prolonged treatments result in selection for female preference against sterile males. In this paper we extend a general differential equation model of mosquito dynamics to consider the role of female choosiness in determining the long-term usefulness of SIT as a management option. We then apply optimal control theory to our model and show how natural selection for female choosiness fundamentally alters management strategies. Our study calls into question the benefits associated with developing SIT as a management strategy, and suggests that effort should be spent studying female mate choice in order to determine its relative importance and how likely it is to impact SIT treatment goals. PMID:22617381

  18. Next Generation Nuclear Plant Materials Selection and Qualification Program Plan

    SciTech Connect

    R. Doug Hamelin; G. O. Hayner

    2004-11-01

    The U.S. Department of Energy (DOE) has selected the Very High Temperature Reactor (VHTR) design for the Next Generation Nuclear Plant (NGNP) Project. The NGNP will demonstrate the use of nuclear power for electricity and hydrogen production without greenhouse gas emissions. The reactor design is a graphite-moderated, helium-cooled, prismatic or pebble bed thermal neutron spectrum reactor with an average reactor outlet temperature of at least 1000 C. The NGNP will use very high burn up, lowenriched uranium, TRISO-Coated fuel in a once-through fuel cycle. The design service life of the NGNP is 60 years.

  19. Fitness consequences of plants growing with siblings: reconciling kin selection, niche partitioning and competitive ability

    PubMed Central

    File, Amanda L.; Murphy, Guillermo P.; Dudley, Susan A.

    2012-01-01

    Plant studies that have investigated the fitness consequences of growing with siblings have found conflicting evidence that can support different theoretical frameworks. Depending on whether siblings or strangers have higher fitness in competition, kin selection, niche partitioning and competitive ability have been invoked. Here, we bring together these processes in a conceptual synthesis and argue that they can be co-occurring. We propose that these processes can be reconciled and argue for a trait-based approach of measuring natural selection instead of the fitness-based approach to the study of sibling competition. This review will improve the understanding of how plants interact socially under competitive situations, and provide a framework for future studies. PMID:22072602

  20. Plant-Derived Natural Products as Sources of Anti-Quorum Sensing Compounds

    PubMed Central

    Koh, Chong-Lek; Sam, Choon-Kook; Yin, Wai-Fong; Tan, Li Ying; Krishnan, Thiba; Chong, Yee Meng; Chan, Kok-Gan

    2013-01-01

    Quorum sensing is a system of stimuli and responses in relation to bacterial cell population density that regulates gene expression, including virulence determinants. Consequently, quorum sensing has been an attractive target for the development of novel anti-infective measures that do not rely on the use of antibiotics. Anti-quorum sensing has been a promising strategy to combat bacterial infections as it is unlikely to develop multidrug resistant pathogens since it does not impose any selection pressure. A number of anti-quorum sensing approaches have been documented and plant-based natural products have been extensively studied in this context. Plant matter is one of the major sources of chemicals in use today in various industries, ranging from the pharmaceutical, cosmetic, and food biotechnology to the textile industries. Just like animals and humans, plants are constantly exposed to bacterial infections, it is therefore logical to expect that plants have developed sophisticated of chemical mechanisms to combat pathogens. In this review, we have surveyed the various types of plant-based natural products that exhibit anti-quorum sensing properties and their anti-quorum sensing mechanisms. PMID:23669710

  1. Exploring the Potential for Using Inexpensive Natural Reagents Extracted from Plants to Teach Chemical Analysis

    ERIC Educational Resources Information Center

    Hartwell, Supaporn Kradtap

    2012-01-01

    A number of scientific articles report on the use of natural extracts from plants as chemical reagents, where the main objective is to present the scientific applications of those natural plant extracts. The author suggests that natural reagents extracted from plants can be used as alternative low cost tools in teaching chemical analysis,…

  2. Natural selection for costly nutrient recycling in simulated microbial metacommunities.

    PubMed

    Boyle, Richard A; Williams, Hywel T P; Lenton, Timothy M

    2012-11-01

    Recycling of essential nutrients occurs at scales from microbial communities to global biogeochemical cycles, often in association with ecological interactions in which two or more species utilise each others' metabolic by-products. However, recycling loops may be unstable; sequences of reactions leading to net recycling may be parasitised by side-reactions causing nutrient loss, while some reactions in any closed recycling loop are likely to be costly to participants. Here we examine the stability of nutrient recycling loops in an individual-based ecosystem model based on microbial functional types that differ in their metabolism. A supplied nutrient is utilised by a "source" functional type, generating a secondary nutrient that is subsequently used by two other types-a "mutualist" that regenerates the initial nutrient at a growth rate cost, and a "parasite" that produces a refractory waste product but does not incur any additional cost. The three functional types are distributed across a metacommunity in which separate patches are linked by a stochastic diffusive migration process. Regions of high mutualist abundance feature high levels of nutrient recycling and increased local population density leading to greater export of individuals, allowing the source-mutualist recycling loop to spread across the system. Individual-level selection favouring parasites is balanced by patch-level selection for high productivity, indirectly favouring mutualists due to the synergistic productivity benefits of the recycling loop they support. This suggests that multi-level selection may promote nutrient cycling and thereby help to explain the apparent ubiquity and stability of nutrient recycling in nature. PMID:22842011

  3. Kainic Acid-Induced Excitotoxicity Experimental Model: Protective Merits of Natural Products and Plant Extracts

    PubMed Central

    Mohd Sairazi, Nur Shafika; Sirajudeen, K. N. S.; Asari, Mohd Asnizam; Muzaimi, Mustapha; Mummedy, Swamy; Sulaiman, Siti Amrah

    2015-01-01

    Excitotoxicity is well recognized as a major pathological process of neuronal death in neurodegenerative diseases involving the central nervous system (CNS). In the animal models of neurodegeneration, excitotoxicity is commonly induced experimentally by chemical convulsants, particularly kainic acid (KA). KA-induced excitotoxicity in rodent models has been shown to result in seizures, behavioral changes, oxidative stress, glial activation, inflammatory mediator production, endoplasmic reticulum stress, mitochondrial dysfunction, and selective neurodegeneration in the brain upon KA administration. Recently, there is an emerging trend to search for natural sources to combat against excitotoxicity-associated neurodegenerative diseases. Natural products and plant extracts had attracted a considerable amount of attention because of their reported beneficial effects on the CNS, particularly their neuroprotective effect against excitotoxicity. They provide significant reduction and/or protection against the development and progression of acute and chronic neurodegeneration. This indicates that natural products and plants extracts may be useful in protecting against excitotoxicity-associated neurodegeneration. Thus, targeting of multiple pathways simultaneously may be the strategy to maximize the neuroprotection effect. This review summarizes the mechanisms involved in KA-induced excitotoxicity and attempts to collate the various researches related to the protective effect of natural products and plant extracts in the KA model of neurodegeneration. PMID:26793262

  4. Potential of Plant-Derived Natural Products in the Treatment of Leukemia and Lymphoma

    PubMed Central

    Lucas, David M.; Still, Patrick C.; Pérez, Lynette Bueno; Grever, Michael R.; Kinghorn, A. Douglas

    2010-01-01

    Hematologic malignancies account for a substantial percentage of cancers worldwide, and the heterogeneity and biological characteristics of leukemias and lymphomas present unique therapeutic challenges. Although treatment options exist for most of these diseases, many types remain incurable and the emergence of drug resistance is pervasive. Thus, novel treatment approaches are essential to improve outcome. Nearly half of the agents used in cancer therapy today are either natural products or derivatives of natural products. The enormous chemical diversity in nature, coupled with millennia of biological selection, has generated a vast and underexplored reservoir of unique chemical structures with biologic activity. This review will describe the investigation and application of natural products derived from higher plants in the treatment of leukemia and lymphoma and the rationale behind these efforts. In addition to the approved vinca alkaloids and the epipodophyllotoxin derivatives, a number of other plant compounds have shown promise in clinical trials and in preclinical investigations. In particular, we will focus on the discovery and biological evaluation of the plant-derived agent silvestrol, which shows potential for additional development as a new therapeutic agent for B-cell malignancies including chronic lymphocytic leukemia. PMID:20370646

  5. Immunology (1955-1975): the natural selection theory, the two signal hypothesis and positive repertoire selection.

    PubMed

    Forsdyke, Donald R

    2012-01-01

    Observations suggesting the existence of natural antibody prior to exposure of an organism to the corresponding antigen, led to the natural selection theory of antibody formation of Jerne in 1955, and to the two signal hypothesis of Forsdyke in 1968. Aspects of these were not only first discoveries but also foundational discoveries in that they influenced contemporaries in a manner that, from our present vantage point, appears to have been constructive. Jerne's later hypothesis (1971, European Journal of Immunology 1: 1-9), that antibody-like receptors on lymphocytes were selected over evolutionary time for reactivity with the major histocompatibility complex (MHC) antigens of the species, was a first, but it was incorrect, and was foundational only to the extent that it emphasized the need to explain the Simonsen phenomenon. Although easily construed as derivative of Jerne (1971), the affinity/avidity model of Forsdyke (1975, Journal of Theoretical Biology 52: 187-198), which predicted that cell-surface components, including MHC antigens, would restrict antigen-reactivity by somatically shaping lymphocyte repertoires, was actually an extension of the two signal hypothesis. While presenting a mechanism for the positive selection of lymphocyte repertoires, and explaining the Simonsen phenomenon, the affinity/avidity model was not foundational in that it had to be independently rediscovered. For science to advance optimally we must seek to close temporal gaps so that first discoveries are also foundational. Listening to young scientists may be part of the solution. PMID:21336661

  6. Interactions in Natural Colloid Systems "Biosolids" - Soil and Plant

    NASA Astrophysics Data System (ADS)

    Kalinichenko, Kira V.; Nikovskaya, Galina N.; Ulberg, Zoya R.

    2016-04-01

    The "biosolids" are complex biocolloid system arising in huge amounts (mln tons per year) from biological municipal wastewater treatment. These contain clusters of nanoparticles of heavy metal compounds (in slightly soluble or unsoluble forms, such as phosphates, sulphates, carbonates, hydroxides, and etc.), cells, humic substances and so on, involved in exopolysaccharides (EPS) net matrix. One may consider that biosolids are the natural nanocomposite. Due to the presence of nitrogen, phosphorus, potassium and other macro- and microelements (heavy metals), vitamins, aminoacids, etc., the biosolids are a depot of bioelements for plant nutrition. Thus, it is generally recognized that most rationally to utilize them for land application. For this purpose the biocolloid process was developed in biosolids system by initiation of microbial vital ability followed by the synthesis of EPS, propagation of ecologically important microorganisms, loosening of the structure and weakening of the coagulation contacts between biosolids colloids, but the structure integrity maintaining [1,2]. It was demonstrated that the applying of biosolids with metabolizing microorganisms to soil provided the improving soil structure, namely the increasing of waterstable aggregates content (70% vs. 20%). It occurs due to flocculation ability of biosolids EPS. The experimental modelling of mutual interactions in systems of soils - biosolids (with metabolizing microorganisms) were realized and their colloid and chemical mechanisms were formulated [3]. As it is known, the most harmonious plant growth comes at a prolonged entering of nutrients under the action of plant roots exudates which include pool of organic acids and polysaccharides [4]. Special investigations showed that under the influence of exudates excreted by growing plants, the biosolids microelements can release gradually from immobilized state into environment and are able to absorb by plants. Thus, the biosolids can serve as an active

  7. Research highlights: natural passive samplers--plants as biomonitors.

    PubMed

    Lin, Vivian S

    2015-06-01

    In the past decade, interest in boosting the collection of data on environmental pollutants while reducing costs has spurred intensive research into passive samplers, instruments that monitor the environment through the free flow of chemical species. These devices, although relatively inexpensive compared to active sampling technologies, are often tailored for collection of specific contaminants or monitoring of a single phase, typically water or air. Plants as versatile, natural passive samplers have gained increased attention in recent years due to their ability to absorb a diverse range of chemicals from the air, water, and soil. Trees, lichens, and other flora have evolved exquisite biological features to facilitate uptake of nutrients and water from the ground and conduct gas exchange on an extraordinary scale, making them excellent monitors of their surroundings. Sampling established plant specimens in a region also provides both historical and spatial data on environmental contaminants at relatively low cost in a non-invasive manner. This Highlight presents several recent publications that demonstrate how plant biomonitoring can be used to map the distribution of a variety of pollutants and identify their sources. PMID:25980391

  8. Plants adapted to warmer climate do not outperform regional plants during a natural heat wave.

    PubMed

    Bucharova, Anna; Durka, Walter; Hermann, Julia-Maria; Hölzel, Norbert; Michalski, Stefan; Kollmann, Johannes; Bossdorf, Oliver

    2016-06-01

    With ongoing climate change, many plant species may not be able to adapt rapidly enough, and some conservation experts are therefore considering to translocate warm-adapted ecotypes to mitigate effects of climate warming. Although this strategy, called assisted migration, is intuitively plausible, most of the support comes from models, whereas experimental evidence is so far scarce. Here we present data on multiple ecotypes of six grassland species, which we grew in four common gardens in Germany during a natural heat wave, with temperatures 1.4-2.0°C higher than the long-term means. In each garden we compared the performance of regional ecotypes with plants from a locality with long-term summer temperatures similar to what the plants experienced during the summer heat wave. We found no difference in performance between regional and warm-adapted plants in four of the six species. In two species, regional ecotypes even outperformed warm-adapted plants, despite elevated temperatures, which suggests that translocating warm-adapted ecotypes may not only lack the desired effect of increased performance but may even have negative consequences. Even if adaptation to climate plays a role, other factors involved in local adaptation, such as biotic interactions, may override it. Based on our results, we cannot advocate assisted migration as a universal tool to enhance the performance of local plant populations and communities during climate change. PMID:27516871

  9. Selective toxicity of Catechin-a natural flavonoid towards bacteria.

    PubMed

    Fathima, Aafreen; Rao, Jonnalagadda Raghava

    2016-07-01

    Catechin is a plant polyphenol composed of epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) as diastereoisomers. Among the various classes of flavonoids, catechin was found to be the most powerful free radical scavenger, scavenging the reactive oxygen species (ROS) generated due to oxidative damage with antibacterial and anti-inflammatory activity. The toxicity of catechin towards bacteria was studied using gram-positive bacteria (B. subtilis) and gram-negative bacteria (E. coli) as model organisms and was found to be more toxic towards gram-positive bacteria. From the results, catechin was found to be beneficial as well as toxic (inhibitory) to the bacteria at a selective concentration behaving as double-edged swords with an IC50 value of 9 ppm for both the bacteria. The inhibitory mechanism of catechin was by oxidative damage through membrane permeabilization which was confirmed by the formation and treatment of bacterial liposomes. SEM images of the control and treated bacteria reveals membrane damage with morphological changes. PMID:27052380

  10. Missing domesticated plant forms: can artificial selection fill the gap?

    PubMed Central

    Van Tassel, David L; DeHaan, Lee R; Cox, Thomas S

    2010-01-01

    In the course of their evolution, the angiosperms have radiated into most known plant forms and life histories. Their adaptation to a recently created habitat, the crop field, produced a novel form: the plant that allocates an unprecedented 30–60% of its net productivity to sexual structures. Long-lived trees, shrubs and vines of this form evolved, as did annual herbs. Perennial herb forms with increased allocation to asexual reproduction evolved, but there are no examples of perennial herbs with high sexual effort. We suggest that sowing seed into annually tilled fields favored shorter-lived herbs because of trade-offs between first-year seed production and relative growth rate and/or persistence. By propagating cuttings, people quickly domesticated tuber crops and large woody plants. Perennial herbs were too small to be efficiently propagated by cuttings, and the association between longevity, allogamy and genetic load made rapid domestication by sexual cycles unlikely. Perennial grain crops do not exist because they could not have evolved under the original set of conditions; however, they can be deliberately developed today through artificial phenotypic and genotypic selection. PMID:25567937

  11. Behavior of Selected Endocrine Disrupting Chemicals in Sewage Treatment Plant

    NASA Astrophysics Data System (ADS)

    Wang, Xinze; Lu, Jiaming; Ollivier, Natacha; Saturnino, Anais; Gomez, Elena; Casellas, Claude; Picot, Bernadette

    2010-11-01

    The behavior of endocrine disrupting chemicals in sewage treatment plant affects their final fate in water environment. We selected six endocrine disrupting chemicals: 4 alkylphenols (4-tert-octylphenol, octylphenol, 4-nonylphenol, bisphenol A) and 2 steroids (17α-ethinylestradiol and estriol) as targets, their removal and transformation in wastewater treatment plant were studied. Five mixed liquors were sampled respectively from different stages of Minhang wastewater treatment plant in Shanghai. EDCs concentration were analyzed with GC-MS. The main removal pathways of EDCs include initial adsorption by suspended solids and following biodegradation in biological sludge. The removal efficiency of six targets was more than 86%. The concentration of OP and 4-n-NP in water significantly increased in anoxic stage, the reason may be the releases of EDCs from sludge to water on the condition of low DO. And it was also found that the EDCs could be released to water phase in the secondary clarifier, which may cause potential risk of EDCs entering the environment with discharge.

  12. Antileishmanial, antitrypanosomal, and cytotoxic screening of ethnopharmacologically selected Peruvian plants.

    PubMed

    González-Coloma, Azucena; Reina, Matías; Sáenz, Claudia; Lacret, Rodney; Ruiz-Mesia, Lastenia; Arán, Vicente J; Sanz, Jesús; Martínez-Díaz, Rafael A

    2012-04-01

    Extracts (34) from eight plant species of the Peruvian Amazonia currently used in traditional Peruvian medicine, mostly as antileishmanial remedies and also as painkiller, antiseptic, antipyretic, anti-inflamatory, antiflu, astringent, diuretic, antipoison, anticancerous, antiparasitic, insecticidal, or healing agents, have been tested for their antileishmanial, antitrypanosomal, and cytotoxic activity. Plant species were selected based on interviews conducted with residents of rural areas. The different plant parts were dried, powdered, and extracted by maceration with different solvents (hexane, chloroform, and 70% ethanol-water). These extracts were tested on promastigote forms of Leishmania infantum strain PB75, epimastigote forms of Trypanosoma cruzi strain Y, and the mammalian CHO cell line. Parasite viability and nonspecific cytotoxicity were analyzed by a modified MTT colorimetric assay method. The isolation and identification of pure compounds from selected extracts were performed by column chromatography, gas chromatography mass spectrometry (GC-MS; mixtures), spectroscopic techniques [MS, infrared (IR), ultraviolet (UV)], and mono and two-dimensional (1)H and (13)C nuclear magnetic resonance (NMR; COSY, HSQC, NOESY) experiments. Chondodendron tomentosum bark and Cedrela odorata were the most active extracts against Leishmania, while C. odorata and Aristoloquia pilosa were the most active against Trypanosoma, followed by Tabebuia serratifolia, Tradescantia zebrina, and Zamia ulei. Six compounds and two mixtures were isolated from Z. ulei [cycasin (1)], T. serratifolia {mixtures 1-2, and naphthoquinones 2-acetyl-4H,9H-naphtho[2,3-b]furan-4,9-dione (2) and 2-(1-hydroxyethyl)-4H,9H-naphtho[2,3-b]furan-4,9-dione (3)}, and C. tomentosum [chondrocurine (4); (S,S')-12-O-methyl(+)-curine (5); and cycleanine (6)]. Four compounds and the two mixtures exhibited significant activity. PMID:21922239

  13. Positive Selection of the Hrp Pilin HrpE of the Plant Pathogen Xanthomonas

    PubMed Central

    Weber, Ernst; Koebnik, Ralf

    2006-01-01

    The plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria possesses a type III secretion (TTS) system which is encoded by the 23-kb hrp (hypersensitive response and pathogenicity) gene cluster. The TTS system is necessary for pathogenicity in susceptible hosts and induction of the hypersensitive response in resistant plants. At the cell surface, the TTS system is associated with an extracellular filamentous structure, the Hrp pilus, which serves as a conduit for the transfer of bacterial proteins into the plant cell cytosol. The major pilus component, the HrpE pilin, is unique to xanthomonads. Previous work showed that HrpE contains two regions: a hypervariable surface-exposed domain, including the N-terminal secretion signal, and a C-terminal polymerization domain. In this study, the evolutionary rate of the hrpE gene was analyzed. Twenty-one alleles were cloned, sequenced, and compared with five known hrpE alleles. The ratio of synonymous (Ks) and nonsynonymous (Ka) substitution rates shows that parts of the HrpE N terminus are subjected to positive selection and the C terminus is subjected to purifying selection. The trade-off between positive and purifying selection at the very-N terminus allowed us to ascertain the amphipathic α-helical nature of the TTS signal. This is the first report of a surface structure from a plant-pathogenic bacterium that evolved under the constraint of positive selection and hints to the evolutionary adaptation of this extracellular appendage to avoid recognition by the plant defense surveillance system. PMID:16452423

  14. Epistasis underlying a fitness trait within a natural population of the pitcher-plant mosquito, Wyeomyia smithii.

    PubMed

    Bradshaw, William E; Haggerty, Brian P; Holzapfel, Christina M

    2005-01-01

    We selected on divergent photoperiodic response in three separate lines from a natural population of the pitcher-plant mosquito, Wyeomyia smithii. Line crosses reveal that there exists within a population, diverse epistatic variation for a fitness trait that could contribute to adaptive potential following founder events or rapid climate change. PMID:15466431

  15. Epistasis Underlying a Fitness Trait Within a Natural Population of the Pitcher-Plant Mosquito, Wyeomyia smithii

    PubMed Central

    Bradshaw, William E.; Haggerty, Brian P.; Holzapfel, Christina M.

    2005-01-01

    We selected on divergent photoperiodic response in three separate lines from a natural population of the pitcher-plant mosquito, Wyeomyia smithii. Line crosses reveal that there exists within a population, diverse epistatic variation for a fitness trait that could contribute to adaptive potential following founder events or rapid climate change. PMID:15466431

  16. Gut wall bacteria of earthworms: a natural selection process.

    PubMed

    Thakuria, Dwipendra; Schmidt, Olaf; Finan, Dillon; Egan, Damian; Doohan, Fiona M

    2010-03-01

    Earthworms and microorganisms are interdependent and their interactions regulate the biogeochemistry of terrestrial soils. Investigating earthworm-microorganism interactions, we tested the hypothesis that differences in burrowing and feeding habits of anecic and endogeic earthworms are reflected by the existence of ecological group-specific gut wall bacterial communities. Bacterial community was detected using automated ribosomal intergenic spacer analysis of 16S and 23S genes and ribotype data was used to assess diversity and community composition. Using soil and earthworm samples collected from adjacent wheat-barley and grass-clover fields, we found that the anecic Lumbricus terrestris and L. friendi, the endogeic Aporrectodea caliginosa and A. longa (classically defined as anecic, but now known to possess endogeic characteristics) contain ecological group-specific gut wall-associated bacterial communities. The abundance of specific gut wall-associated bacteria (identified by sequence analysis of ribotype bands), including Proteobacteria, Firmicutes and an actinobacterium, was ecological group dependent. A microcosm study, conducted using A. caliginosa and L. terrestris and five different feeding regimes, indicated that food resource can cause shifts in gut wall-associated bacterial community, but the magnitude of these shifts did not obscure the delineation between ecological group specificity. Using A. caliginosa and A. longa samples collected in six different arable fields, we deduced that, within an ecological group, habitat was a more important determinant of gut wall-associated bacterial community composition than was host species. Hence, we conclude that the selection of bacteria associated with the gut wall of earthworms is a natural selection process and the strongest determinant of this process is in the order ecological group>habitat>species. PMID:19924156

  17. Plant selection for dewatering and reclamation of tailings

    SciTech Connect

    Silva, M.J.; Naeth, M.A.; Biggar, K.W.; Chanasyk, D.S.; Sego, D.C.

    1998-12-31

    A two-phase greenhouse experiment was conducted to identify the most suitable species for dewatering and reclamation of Composite Tailings (CT) from Alberta oil sands operated by Syncrude Canada Ltd. and Copper Mine Tailings (CMT) from the Kennecott site in Utah. A total of 15 and 9 plant species were selected for testing in CT and CMT, respectively. In Phase 1, distilled water was added weekly to simulate local precipitation. The initial solids content were 80% and 76% and the electrical conductivities were 1.1 dS/m and 3.2 dS/m for CT and CMT, respectively. All plants survived after a ten-week period. In Phase 2 only process water was added weekly to provide a worst case scenario of no precipitation and water recharge due only to process water being released from within the tailings. The initial solids contents were 65% and 76% for CT and CMT, respectively. Surface (0--3 in.) salinity increased dramatically due to the application of process water only; at the end of Phase 2 it had reached toxic levels of approximately 18.9 dS/m and 35.0 dS/m in CT and CMT, respectively. Many plants showed signs of stress due to the high salinity level. The plants which performed the best under both phases in Composite Tailings were creeping foxtail (Alopecurus arundinaceus), reed canarygrass (Phalaris arundinacea), Altai wildrye (Elymus angustus), and red top (Agrostis stolonifera); and in Copper Mine Tailings were Altai wildrye, smooth bromegrass (Bromus inermis) and creeping foxtail.

  18. Chiral Selective Chemistry Induced by Natural Selection of Spin-Polarized Electrons.

    PubMed

    Rosenberg, Richard A; Mishra, Debabrata; Naaman, Ron

    2015-06-15

    The search to understand the origin of homochirality in nature has been ongoing since the time of Pasteur. Previous work has shown that DNA can act as a spin filter for low-energy electrons and that spin-polarized secondary electrons produced by X-ray irradiation of a magnetic substrate can induce chiral selective chemistry. In the present work it is demonstrated that secondary electrons from a substrate that are transmitted through a chiral overlayer cause enantiomeric selective chemistry in an adsorbed adlayer. We determine the quantum yields (QYs) for dissociation of (R)- or (S)-epichlorohydrin adsorbed on a chiral self-assembled layer of DNA on gold and on bare gold (for control). The results show that there is a significant difference in the QYs between the two enantiomers when adsorbed on DNA, but none when they are adsorbed on bare Au. We propose that the effect results from natural spin filtering effects cause by the chiral monolayer. PMID:25950284

  19. Antimicrobial evaluation of selected naturally occurring oxyprenylated secondary metabolites.

    PubMed

    Di Giulio, Mara; Genovese, Salvatore; Fiorito, Serena; Epifano, Francesco; Nostro, Antonia; Cellini, Luigina

    2016-08-01

    This study tested the antimicrobial activity of eight selected naturally occurring oxyprenylated secondary metabolites against Staphylococcus aureus ATCC 29213, S. epidermidis ATCC 35984, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 9027 and Candida albicans ATCC 10231. Results showed a moderate antimicrobial activity. The most active compounds were 3-(4-geranyloxyphenyl)-1-ethanol (4) and 3-(4-isopentenyloxyphenyl)-1-propanol (5) that were tested on mature and in-formation biofilms of all micro-organisms, moreover the cytotoxic activity was evaluated. Except for S. epidermidis, both compounds reduced significantly (p < 0.05) the microbial biofilm formation at 1/2 MIC and 1/4 MIC, in particular, compounds 4 and 5 at each concentration, inhibited E. coli biofilm formation to a greater extent, the biofilm formation was never more than 44% in respect to the control, moreover both compounds showed a low cytotoxic effect. Oxyprenylated derivatives may be of great interest for the development of novel antimicrobial therapeutic strategies and the synthesis of semi-synthetic analogues with anti-biofilm efficacy. PMID:27498831

  20. Relaxed natural selection in human populations during the Pleistocene.

    PubMed

    Takahata, N

    1993-12-01

    Available genetic data reveals that the human population is more variable than the chimpanzee population at the protein level, whereas the opposite is the case at the DNA level. The lower level of silent polymorphism in the human population suggests that its long-term breeding size is smaller than the chimpanzee's. The neutral theory suggests that natural selection has been relaxed in the human population under the improved environment. The possibility that the relaxation began with the emergence of Homo sapiens is examined, because it is known that H. habilis underwent for the first time dramatic changes in brain size, way of life, and culture, and that the childhood of H. erectus was already twice as long as that of chimpanzee. The relaxation hypothesis predicts that, relative to chimpanzee, some 20% of deleterious mutations became harmless under the changed environment throughout the Pleistocene. More extensive study of genetic variation in non-human primates is necessary not only to confirm the hypothesis, but also to better understand the human genome itself. PMID:8031575

  1. Student conceptions of natural selection and its role in evolution

    NASA Astrophysics Data System (ADS)

    Bishop, Beth A.; Anderson, Charles W.

    Pretests and posttests on the topic of evolution by natural selection were administered to students in a college nonmajors' biology course. Analysis of test responses revealed that most students understood evolution as a process in which species respond to environmental conditions by changing gradually over time. Student thinking differed from accepted biological theory in that (a) changes in traits were attributed to a need-driven adaptive process rather than random genetic mutation and sexual recombination, (b) no role was assigned to variation on traits within a population or differences in reproductive success, and (c) traits were seen as gradually changing in all members of a population. Although students had taken an average of 1.9 years of previous biology courses, performance on the pretest was uniformly low. There was no relationship between the amount of previous biology taken and either pretest or posttest performance. Belief in the truthfulness of evolutionary theory was also unrelated to either pretest or posttest performance. Course instruction using specially designed materials was moderately successful in improving students' understanding of the evolutionary process.

  2. Testing Transgenic Aspen Plants with bar Gene for Herbicide Resistance under Semi-natural Conditions

    PubMed Central

    Lebedev, V. G.; Faskhiev, V. N.; Kovalenko, N. P.; Shestibratov, K. A.; Miroshnikov, A. I.

    2016-01-01

    Obtaining herbicide resistant plants is an important task in the genetic engineering of forest trees. Transgenic European aspen plants (Populus tremula L.) expressing the bar gene for phosphinothricin resistance have been produced using Agrobacterium tumefaciens-mediated transformation. Successful genetic transformation was confirmed by PCR analysis for thirteen lines derived from two elite genotypes. In 2014–2015, six lines were evaluated for resistance to herbicide treatment under semi-natural conditions. All selected transgenic lines were resistant to the herbicide Basta at doses equivalent to 10 l/ha (twofold normal field dosage) whereas the control plants died at 2.5 l/ha. Foliar NH4-N concentrations in transgenic plants did not change after treatment. Extremely low temperatures in the third ten-day period of October 2014 revealed differences in freeze tolerance between the lines obtained from Pt of f2 aspen genotypes. Stable expression of the bar gene after overwintering outdoors was confirmed by RT-PCR. On the basis of the tests, four transgenic aspen lines were selected. The bar gene could be used for retransformation of transgenic forest trees expressing valuable traits, such as increased productivity. PMID:27437143

  3. Evaluation of cesium selective media at the Callaway Plant

    SciTech Connect

    Miller, B.

    1996-10-01

    Based on the desire to lower costs, public dose and in-plant exposure, Callaway Nuclear Plant evaluated the prospect of changing their liquid waste processing from evaporation to demineralization. Approximately 95% of Callaway`s annual dose to the total body can be attributed to cesium. During normal plant operations, Callaway`s influent Cs-137 level averages 3E{minus}5 {mu}Ci/ml. During episodes of failed fuel, Cs-137 rises to approximately 3E{minus}3 {mu}Ci/ml. Plant criteria specify that the Cs-137 effluent remain below 5E{minus}7 (average Minimum Detectable Activity) to maintain the required 1% dose to the public (exclusive of tritium). From February, 1995 through February, 1996, extensive testing of the capacities and associated Decontamination Factors (DF) for cesium specific media were conducted. Two media were selected for testing based on their capacity for cesium in high conductivity water. During bench scale testing, one media, CsTreat, performed well below the 1% dose parameter (0.2%) during the equivalent of processing 28,300 gallon/cu ft media. The test was ended based on time constraints rather than loss of ion exchange capacity. At the end of processing this 28,300 gallon/cu ft equivalent, the effluent Cs-137 level remained below MDA. The same test bed was then subjected to simulated waste water that would be seen during a cycle with significant fuel failures. Callaway chemists injected Cs-137 into their Floor Drain Tank (FDT) water increasing the influent level to 1.6E{minus}2 {mu}Ci/ml. The effluent Cs-137 level was measured at 3.5E{minus}6 {mu}Ci/ml giving an associated DF of 3949. Anticipated DF for full scale application is 5000 to 10000, which would maintain Callaway below the 1% dose goal for effluent during a cycle with failed fuel. Based on these results and the associated cost benefit, Callaway Plant will switch their radwaste processing from evaporation to filtration and ion exchange including CsTreat media.

  4. Natural colloidal P and its contribution to plant P uptake.

    PubMed

    Montalvo, Daniela; Degryse, Fien; McLaughlin, Mike J

    2015-03-17

    Phosphorus (P) bioavailability depends on its concentration and speciation in solution. Andisols and Oxisols have very low soil solution concentration of free orthophosphate, as they contain high concentrations of strongly P-sorbing minerals (Al/Fe oxyhydroxides, allophanes). Free orthophosphate is the form of P taken up by plants, but it is not the only P species present in the soil solution. Natural colloidal P (P associated with Al, Fe, and organic matter of sizes ranging from 1 to 1000 nm) constitutes an important fraction of soil solution P in these soils; however, its availability has not been considered. We measured the uptake of P by wheat (Triticum aestivum) from radiolabeled nonfiltered (colloid-containing) and 3-kDa filtered (nearly colloid-free) soil-water extracts from Andisols and Oxisols. In the Andisol extracts, P uptake was up to 5-fold higher from the nonfiltered solutions than the corresponding 3-kDa filtered solutions. In the Oxisol extract, no difference in P uptake between both solutions was observed. Also the diffusional flux of P as measured with the DGT technique was larger in the nonfiltered than in the 3-kDa filtered solutions. Our results suggest that colloidal P from Andisols is not chemically inert and contributes to plant uptake of P. PMID:25719745

  5. Epistasis in natural populations of a predominantly selfing plant

    PubMed Central

    Volis, S; Shulgina, I; Zaretsky, M; Koren, O

    2011-01-01

    Populations of predominantly selfing plant species often show spatial genetic structure but little is known whether epistatic gene interactions are spatially structured. To detect a possible epistatic effect and a spatial scale at which it operates, we created artificial crosses between plants spanning a range of fixed distances from 1 to 400 m in three populations of wild barley. The self-pollinated and crossed progeny (F1) and two generations of segregated progeny (F2 and F3) were tested in experimentally simulated population environments for relative performance (RP). The measured fitness traits included number of seeds, total seed weight and seed germination. For any of these traits, there was no association between RP of F1, F2 and F3 plants and either pairwise kinship coefficients or crossing distance. In contrast, in all three populations, we found lower seed viability of outcrossed as compared with self-pollinated genotypes in the first generation of segregation. However, in the F3 generation this outbreeding effect disappeared in the two populations and greatly decreased in the third population. For seed production, heterosis in F1 and outbreeding depression in F2 were observed only in the population with unusually high number of heterozygotes. Our findings support the view that in selfing species a spatial mosaic of various locally abundant genotypes represents not randomly fixed combinations of alleles but the co-adapted gene complexes that were sieved by selection, while heterozygotes are characteristic for the transient phase of this process, when segregation and purging of maladaptive genotypes have not yet occurred. PMID:20551977

  6. Nitrate dynamics in natural plants: insights based on the concentration and natural isotope abundances of tissue nitrate

    PubMed Central

    Liu, Xue-Yan; Koba, Keisuke; Makabe, Akiko; Liu, Cong-Qiang

    2014-01-01

    The dynamics of nitrate (NO−3), a major nitrogen (N) source for natural plants, has been studied mostly through experimental N addition, enzymatic assay, isotope labeling, and genetic expression. However, artificial N supply may not reasonably reflect the N strategies in natural plants because NO−3 uptake and reduction may vary with external N availability. Due to abrupt application and short operation time, field N addition, and isotopic labeling hinder the elucidation of in situ NO−3-use mechanisms. The concentration and natural isotopes of tissue NO−3 can offer insights into the plant NO−3 sources and dynamics in a natural context. Furthermore, they facilitate the exploration of plant NO−3 utilization and its interaction with N pollution and ecosystem N cycles without disturbing the N pools. The present study was conducted to review the application of the denitrifier method for concentration and isotope analyses of NO−3 in plants. Moreover, this study highlights the utility and advantages of these parameters in interpreting NO−3 sources and dynamics in natural plants. We summarize the major sources and reduction processes of NO−3 in plants, and discuss the implications of NO−3 concentration in plant tissues based on existing data. Particular emphasis was laid on the regulation of soil NO−3 and plant ecophysiological functions in interspecific and intra-plant NO−3 variations. We introduce N and O isotope systematics of NO−3 in plants and discuss the principles and feasibilities of using isotopic enrichment and fractionation factors; the correlation between concentration and isotopes (N and O isotopes: δ18O and Δ17O); and isotope mass-balance calculations to constrain sources and reduction of NO−3 in possible scenarios for natural plants are deliberated. Finally, we offer a preliminary framework of intraplant δ18O-NO−3 variation, and summarize the uncertainties in using tissue NO−3 parameters to interpret plant NO−3 utilization

  7. COMPARATIVE ASSESSMENT OF TOTAL PHENOLIC CONTENT IN SELECTED MEDICINAL PLANTS

    PubMed Central

    Johnson, C.E.; Oladeinde, F. O.; Kinyua, A.M.; Michelin, R.; Makinde, J.M.; Jaiyesimi, A.A.; Mbiti, W.N.; Kamau, G.N.; Kofi-Tsekpo, W.M.; Pramanik, S.; Williams, A.; Kennedy, A.; Bronner, Y.; Clarke, K.; Fofonoff, P.; Nemerson, D.

    2009-01-01

    This study was to compare the total phenolic (TP) content in extracts from eleven plant materials collected at different geographical locations in Kenya, Nigeria, and USA. These plants have been selected because the majority of them are highly pigmented, from yellow to purple, and would therefore have economic value in industries for producing antioxidants and surfactants. Two of them were collected from the industrial and domestic waste outlets. Each analysis was achieved using the Folin-Ciocalteau technique. The order of decreasing phenolic acid content as gallic acid concentration (mg/g dry weight) was Prunus africana (55.14) > Acacia tortilis (42.11) > Khaya grandifoliola (17.54) > Curcuma longa (17.23) > Vernonia amygdalina (14.9)> Russelia equisetiformis (14.03) > Calendula officinalis (7.96) >Phragmites australis (control) (7.09) > Rauwolfia vomitoria (6.69) > Phragmites australis (industrial) (6.21) > Cnidoscolus aconitifolius (5.6). The TP contents of Spartina alterniflora species were below the detection limit. PMID:20119491

  8. COMPARATIVE ASSESSMENT OF TOTAL PHENOLIC CONTENT IN SELECTED MEDICINAL PLANTS.

    PubMed

    Johnson, C E; Oladeinde, F O; Kinyua, A M; Michelin, R; Makinde, J M; Jaiyesimi, A A; Mbiti, W N; Kamau, G N; Kofi-Tsekpo, W M; Pramanik, S; Williams, A; Kennedy, A; Bronner, Y; Clarke, K; Fofonoff, P; Nemerson, D

    2008-01-01

    This study was to compare the total phenolic (TP) content in extracts from eleven plant materials collected at different geographical locations in Kenya, Nigeria, and USA. These plants have been selected because the majority of them are highly pigmented, from yellow to purple, and would therefore have economic value in industries for producing antioxidants and surfactants. Two of them were collected from the industrial and domestic waste outlets. Each analysis was achieved using the Folin-Ciocalteau technique. The order of decreasing phenolic acid content as gallic acid concentration (mg/g dry weight) was Prunus africana (55.14) > Acacia tortilis (42.11) > Khaya grandifoliola (17.54) > Curcuma longa (17.23) > Vernonia amygdalina (14.9)> Russelia equisetiformis (14.03) > Calendula officinalis (7.96) >Phragmites australis (control) (7.09) > Rauwolfia vomitoria (6.69) > Phragmites australis (industrial) (6.21) > Cnidoscolus aconitifolius (5.6). The TP contents of Spartina alterniflora species were below the detection limit. PMID:20119491

  9. Antioxidative activities of aroma extracts isolated from natural plants.

    PubMed

    Lee, K G; Mitchell, A; Shibamoto, T

    2000-01-01

    Natural leaves and flowers containing numerous aroma chemicals are widely used in aromatherapy since ancient times. In addition to their pleasant smells, aroma chemicals might have some beneficial health effects. Aroma extracts, isolated from coffee beans, soybeans, and mung beans by steam distillation under mild conditions (55 degrees C and 85 mm Hg) were examined for their antioxidative activities. The inhibitory effect of these extracts toward hexanal/hexanoic acid conversion was measured in the testing solution over prolonged time periods. The inhibitory effects of these extracts toward malonaldehyde formation from lipids oxidized by Fenton's reagent were also measured. The antioxidative activity of these extracts, in particular coffee bean extract, was consistent with that of BHT or alpha-tocopherol (vitamin E). Soybeans and mung beans extract contained maltol, which inhibits hexanal oxidation significantly. Eugenol, which is one of the major constituents of mung bean extract, exhibited potent antioxidative activity in an aldehyde/carboxylic acid assay. Antioxidants such as eugenol and maltol may play an important role in the pharmaceutical activities of natural plant extracts used for aromatherapy. PMID:11237179

  10. An exotic invasive plant selects for increased competitive tolerance, but not competitive suppression, in a native grass.

    PubMed

    Fletcher, Rebecca A; Callaway, Ragan M; Atwater, Daniel Z

    2016-06-01

    Exotic invasive plants can exert strong selective pressure for increased competitive ability in native plants. There are two fundamental components of competitive ability: suppression and tolerance, and the current paradigm that these components have equal influences on a species' overall competitive ability has been recently questioned. If these components do not have equal influences on overall ability, then selection on competitive tolerance and suppression may be disproportionate. We used naturally invaded communities to study the effects of selection caused by an invasive forb, Centaurea stoebe, on a native grass, Pseudoroegneria spicata. P. spicata plants were harvested from within dense C. stoebe patches and from nearby uninvaded areas, divided clonally into replicates, then transplanted into a common garden where they grew alone or competed with C. stoebe. We found that P. spicata plants collected from within C. stoebe patches were significantly more tolerant of competition with C. stoebe than P. spicata plants collected from uninvaded areas, but plants from inside invaded patches were not superior at suppressing C. stoebe. These results are consistent with the hypothesis that strong competitors may select for tolerance to competition more than for the ability to suppress neighbors. This has important implications for how native plant communities may respond to invasion over time, and how invasive and native species may ultimately coexist. PMID:26897605

  11. Human fertility, molecular genetics, and natural selection in modern societies.

    PubMed

    Tropf, Felix C; Stulp, Gert; Barban, Nicola; Visscher, Peter M; Yang, Jian; Snieder, Harold; Mills, Melinda C

    2015-01-01

    Research on genetic influences on human fertility outcomes such as number of children ever born (NEB) or the age at first childbirth (AFB) has been solely based on twin and family-designs that suffer from problematic assumptions and practical limitations. The current study exploits recent advances in the field of molecular genetics by applying the genomic-relationship-matrix based restricted maximum likelihood (GREML) methods to quantify for the first time the extent to which common genetic variants influence the NEB and the AFB of women. Using data from the UK and the Netherlands (N = 6,758), results show significant additive genetic effects on both traits explaining 10% (SE = 5) of the variance in the NEB and 15% (SE = 4) in the AFB. We further find a significant negative genetic correlation between AFB and NEB in the pooled sample of -0.62 (SE = 0.27, p-value = 0.02). This finding implies that individuals with genetic predispositions for an earlier AFB had a reproductive advantage and that natural selection operated not only in historical, but also in contemporary populations. The observed postponement in the AFB across the past century in Europe contrasts with these findings, suggesting an evolutionary override by environmental effects and underscoring that evolutionary predictions in modern human societies are not straight forward. It emphasizes the necessity for an integrative research design from the fields of genetics and social sciences in order to understand and predict fertility outcomes. Finally, our results suggest that we may be able to find genetic variants associated with human fertility when conducting GWAS-meta analyses with sufficient sample size. PMID:26039877

  12. Human Fertility, Molecular Genetics, and Natural Selection in Modern Societies

    PubMed Central

    Tropf, Felix C.; Stulp, Gert; Barban, Nicola; Visscher, Peter M.; Yang, Jian; Snieder, Harold; Mills, Melinda C.

    2015-01-01

    Research on genetic influences on human fertility outcomes such as number of children ever born (NEB) or the age at first childbirth (AFB) has been solely based on twin and family-designs that suffer from problematic assumptions and practical limitations. The current study exploits recent advances in the field of molecular genetics by applying the genomic-relationship-matrix based restricted maximum likelihood (GREML) methods to quantify for the first time the extent to which common genetic variants influence the NEB and the AFB of women. Using data from the UK and the Netherlands (N = 6,758), results show significant additive genetic effects on both traits explaining 10% (SE = 5) of the variance in the NEB and 15% (SE = 4) in the AFB. We further find a significant negative genetic correlation between AFB and NEB in the pooled sample of –0.62 (SE = 0.27, p-value = 0.02). This finding implies that individuals with genetic predispositions for an earlier AFB had a reproductive advantage and that natural selection operated not only in historical, but also in contemporary populations. The observed postponement in the AFB across the past century in Europe contrasts with these findings, suggesting an evolutionary override by environmental effects and underscoring that evolutionary predictions in modern human societies are not straight forward. It emphasizes the necessity for an integrative research design from the fields of genetics and social sciences in order to understand and predict fertility outcomes. Finally, our results suggest that we may be able to find genetic variants associated with human fertility when conducting GWAS-meta analyses with sufficient sample size. PMID:26039877

  13. Selection of a suitable plant for phytoremediation in mining artisanal zones.

    PubMed

    Chamba, I; Gazquez, M J; Selvaraj, T; Calva, J; Toledo, J J; Armijos, C

    2016-09-01

    A study was undertaken with the aim of identifying a suitable plant for the phytoremediation of metal-polluted soil from an artisanal mining area in Ecuador. Three zones including a natural zone (NZ), abandoned zone (AZ) and intensively mined zone (IZ) were selected. Three common native plants grown in the three zones were identified and collected, including Miconia zamorensis, Axonopus compressus and Erato polymnioides. The percentage of arbuscular mycorrhizal colonization that benefits their own survival in polluted soil was analyzed in the root samples of these candidate species. Analysis of the soils and plants collected from the different zones showed that the concentrations of Pb, Zn, Cu and Cd were comparatively lower in the NZ, higher in the AZ and IZ, and highest in the AZ for all the metals. The concentration of all these metals in plant tissues was the highest in E. polymnioides. The data analysis including the metal accumulation index, bioconcentration factor and translocation factor strongly identified E. polymnioides as a hyperaccumulator plant suitable for phytoremediation. PMID:26940037

  14. Carbon isotope ratios in crassulacean Acid metabolism plants: seasonal patterns from plants in natural stands.

    PubMed

    Szarek, S R

    1976-09-01

    A year round study of photosynthesis and carbon isotope fractionation was conducted with plants of Opuntia phaeacantha Engelm. and Yucca baccata Torr. occurring in natural stands at elevations of 525, 970, 1450 and 1900 m. Plant water potentials and the daytime pattern of (14)CO(2) photosynthesis were similar for all cacti along the elevational gradient, despite significant differences in temperature regime and soil water status. Carbon isotope ratios of total tissue and soluble extract fractions were relatively constant throughtout the entire year. Additionally, the sigma(13)C values were similar in all plants of the same species along the elevational gradient, i.e. -12.5 +/- 0.86 per thousand for O. phaeacantha and -15.7 +/- 0.95 per thousand for Y. baccata. The results of this study indicate Crassulacean acid metabolism predominates as the major carbon pathway of these plants, which do not facultatively utilize the reductive pentose phosphate cycle of photosynthesis as the primary carboxylation reaction. PMID:16659680

  15. Monte Carlo optimization for site selection of new chemical plants.

    PubMed

    Cai, Tianxing; Wang, Sujing; Xu, Qiang

    2015-11-01

    Geographic distribution of chemical manufacturing sites has significant impact on the business sustainability of industrial development and regional environmental sustainability as well. The common site selection rules have included the evaluation of the air quality impact of a newly constructed chemical manufacturing site to surrounding communities. In order to achieve this target, the simultaneous consideration should cover the regional background air-quality information, the emissions of new manufacturing site, and statistical pattern of local meteorological conditions. According to the above information, the risk assessment can be conducted for the potential air-quality impacts from candidate locations of a new chemical manufacturing site, and thus the optimization of the final site selection can be achieved by minimizing its air-quality impacts. This paper has provided a systematic methodology for the above purpose. There are total two stages of modeling and optimization work: i) Monte Carlo simulation for the purpose to identify background pollutant concentration based on currently existing emission sources and regional statistical meteorological conditions; and ii) multi-objective (simultaneous minimization of both peak pollutant concentration and standard deviation of pollutant concentration spatial distribution at air-quality concern regions) Monte Carlo optimization for optimal location selection of new chemical manufacturing sites according to their design data of potential emission. This study can be helpful to both determination of the potential air-quality impact for geographic distribution of multiple chemical plants with respect to regional statistical meteorological conditions, and the identification of an optimal site for each new chemical manufacturing site with the minimal environment impact to surrounding communities. The efficacy of the developed methodology has been demonstrated through the case studies. PMID:26283263

  16. Selection of natural treatment processes for algae removal from stabilisation ponds effluents in Brasilia, using multicriterion methods.

    PubMed

    Neder, K D; Carneiro, G A; Queiroz, T R; de Souza, M A A

    2002-01-01

    A multicriterion methodology is used in the evaluation and selection of the most appropriate alternative(s) for removing algae from stabilisation ponds effluents in a case study in Brasilia. For this purpose, five different natural treatment processes are tested at pilot scale: rock filter, sand filter, floating aquatic plants, constructed wetlands, and overland flow. These pilot units were constructed in Brasilia and set in parallel, each one receiving a portion of the effluent that comes from an existing wastewater treatment plant composed of preliminary treatment, UASB reactors, and high-rate stabilisation ponds. Several evaluation criteria are used in order to relate the capabilities of the post-treatment processes to the multiple objectives in this case. Two multicriterion decision-aid methods--compromise programming and ELECTRE-III--are used to select the most satisfying processes. The top ranking alternatives are indicated for subsequent studies, considering the possible implementation of these technologies to existing plants. PMID:12361031

  17. Animal genetic resources in Brazil: result of five centuries of natural selection.

    PubMed

    Mariante, A da S; Egito, A A

    2002-01-01

    Brazil has various species of domestic animals, which developed from breeds brought by the Portuguese settlers soon after their discovery. For five centuries, these breeds have been subjected to natural selection in specific environments. Today, they present characteristics adapted to the specific Brazilian environmental conditions. These breeds developed in Brazil are known as "Crioulo," "local," or naturalized. From the beginning of the 20th century, some exotic breeds, selected in temperate regions, have begun to be imported. Although more productive, these breeds do not have adaptive traits, such as resistance to disease and parasites found in breeds considered to be "native." Even so, little by little, they replaced the native breeds, to such an extent that the latter are in danger of extinction. In 1983, to avoid the loss of this important genetic material, the National Research Center for Genetic Resources and Biotechnology (Cenargen) of the Brazilian Agricultural Research Corporation (Embrapa) decided to include conservation of animal genetic resources in its research program Conservation and Utilization of Genetic Resources. Until this time, they were only concerned with conservation of native plants. Conservation has been carried out by various research centers of Embrapa, universities, state research corporations, and private farmers, with a single coordinator at the national level, Cenargen. Specifically, conservation is being carried out by conservation nuclei, which are specific herds in which the animals are being conserved, situated in the habitats where the animals have been subjected to natural selection. This involves storage of semen and embryos from cattle, horses, buffaloes, donkeys, goats, sheep, and pigs. The Brazilian Animal Germplasm Bank is kept at Cenargen, which is responsible for the storage of semen and embryos of various breeds of domestic animals threatened with extinction, where almost 45,000 doses of semen and more than 200

  18. Examining undergraduate understanding of natural selection and evolution

    NASA Astrophysics Data System (ADS)

    Balgopal, Meena Michelle

    2007-12-01

    This dissertation explores the understanding of evolution and natural selection by zoology and biological sciences education majors in two upper-division undergraduate courses. To date, there has been little research on evolution misconceptions held by these two populations. Students' misconceptions regarding evolution typically revolve around teleological and Lamarckian explanations for adaptations, origin of variation, and fitness. There are other misconceptions, however, that are described in this dissertation. The overarching objective of the dissertation was to identify variables that might influence the conceptual change. A mixed-method analysis was developed to identify instances of conceptual change that go undetected when only quantitative analyses are used. Through interpretations of in-depth interviews, written discourse, diagnostic tests, instructor interviews, and field notes, it was discovered that students' professional and personal affiliations influenced their motivation to resolve misconceptions. There were three main findings of this doctoral study. First, the effects of direct instruction on misconceptions enabled students to identify incorrect teleological wording but did not necessarily change students' writing about evolution. Higher-achieving students with career interests in biology were more likely to resolve their teleological misconceptions than lower-achieving students. Second, zoology student written discourse could be divided into subjective, objective, and authentic categories based on personal and professional connections that students made in their writing. Students who wrote authentically expressed intentions of pursuing professional biological research. Third, biological sciences education students were found to have composite identities based on personal and professional affiliations, which either hindered or enhanced their motivation to resolve evolution misconceptions. Students' personal affiliations to religious communities

  19. Landscape pattern and its effect on ecosystem functions in Seoul Metropolitan area: urban ecology on distribution of the naturalized plant species.

    PubMed

    Hong, Sun-Kee; Song, In-Ju; Kim, Hyun-Ok; Lee, Eung-Kyong

    2003-03-01

    During land transformation process in the human history, naturalized plants were introduced to several land use patterns by the different ways of plant itself. Including some naturalized plants that had been contribute to land restoration, many naturalized plants have been invaded to original habitat or landscape for native plants. Once the plants were colonized, they extend their area and population size. Urban developed areas often give an important role of source habitat for naturalized plants and expanding their population size. In recent, this situation is appearing as one of environmental problem about the urban landscape management controlling the naturalized plants that invaded in the developed area and conserving the native vegetation. This paper is focusing on relationships between distribution of habitat of naturalized plants and landscape patch in urban areas in Seoul. Gangdong-Gu, one of the administrative areas in Seoul was selected for this study. We examined the recent land use change using LANDSAT TM data and spreading of the representative naturalized plants (Robinia pseudocacia and Eupatorium rugosum) by Seoul Biotope Mapping Project and field survey in 1999. As a result, these two species were often occurred in the same habitat and distributed in forest edge disturbed by man. Their distribution patterns were related to landscape indices (patch size and shape) in the forest edge. PMID:12765262

  20. Melanogenesis and Antityrosinase Activity of Selected South African Plants

    PubMed Central

    Mapunya, Manyatja Brenda; Nikolova, Roumiana Vassileva; Lall, Namrita

    2012-01-01

    Melanin is the pigment that is responsible for the colour of eyes, hair, and skin in humans. Tyrosinase is known to be the key enzyme in melanin biosynthesis. Overactivity of this enzyme leads to dermatological disorders such as age spots, melanoma and sites of actinic damage. Ten plants belonging to four families (Asphodelaceae, Anacardiaceae, Oleaceae, and Rutaceae) were investigated for their effect on tyrosinase using both L-tyrosine and L-DOPA as substrates. Ethanol leaf extracts (500 μg/mL) of Aloe ferox, Aloe aculeata, Aloe pretoriensis, and Aloe sessiliflora showed 60%, 31%, 17%, and 13% inhibition of tyrosinase activity respectively, when L-tyrosine was used as a substrate. Harpephyllum caffrum (leaves) at a concentration of 500 μg/mL had an inhibitory effect of 70% on tyrosinase when L-DOPA was used as a substrate. The IC50 of Harpephyllum caffrum (leaves and bark) were found to be 51 ± 0.002 and 40 ± 0.035 μg/mL, respectively. Following the results obtained from the tyrosinase assay, extracts from Harpephyllum caffrum were selected for further testing on their effect on melanin production and their cytotoxicity on melanocytes in vitro. The IC50 of both extracts was found to be 6.25 μg/mL for melanocyte cells. Bark extract of Harpephyllum caffrum showed 26% reduction in melanin content of melanocyte cells at a concentration of 6.25 μg/mL. The leaf extract of this plant showed some toxicity on melanocyte cells. Therefore, the bark extract of Harpephyllum caffrum could be considered as an antityrosinase agent for dermatological disorders such as age spots and melasoma. PMID:22611429

  1. The neural bases of host plant selection in a Neuroecology framework

    PubMed Central

    Reisenman, Carolina E.; Riffell, Jeffrey A.

    2015-01-01

    Understanding how animals make use of environmental information to guide behavior is a fundamental problem in the field of neuroscience. Similarly, the field of ecology seeks to understand the role of behavior in shaping interactions between organisms at various levels of organization, including population-, community- and even ecosystem-level scales. Together, the newly emerged field of “Neuroecology” seeks to unravel this fundamental question by studying both the function of neurons at many levels of the sensory pathway and the interactions between organisms and their natural environment. The interactions between herbivorous insects and their host plants are ideal examples of Neuroecology given the strong ecological and evolutionary forces and the underlying physiological and behavioral mechanisms that shaped these interactions. In this review we focus on an exemplary herbivorous insect within the Lepidoptera, the giant sphinx moth Manduca sexta, as much is known about the natural behaviors related to host plant selection and the involved neurons at several level of the sensory pathway. We also discuss how herbivore-induced plant odorants and secondary metabolites in floral nectar in turn can affect moth behavior, and the underlying neural mechanisms. PMID:26321961

  2. The neural bases of host plant selection in a Neuroecology framework.

    PubMed

    Reisenman, Carolina E; Riffell, Jeffrey A

    2015-01-01

    Understanding how animals make use of environmental information to guide behavior is a fundamental problem in the field of neuroscience. Similarly, the field of ecology seeks to understand the role of behavior in shaping interactions between organisms at various levels of organization, including population-, community- and even ecosystem-level scales. Together, the newly emerged field of "Neuroecology" seeks to unravel this fundamental question by studying both the function of neurons at many levels of the sensory pathway and the interactions between organisms and their natural environment. The interactions between herbivorous insects and their host plants are ideal examples of Neuroecology given the strong ecological and evolutionary forces and the underlying physiological and behavioral mechanisms that shaped these interactions. In this review we focus on an exemplary herbivorous insect within the Lepidoptera, the giant sphinx moth Manduca sexta, as much is known about the natural behaviors related to host plant selection and the involved neurons at several level of the sensory pathway. We also discuss how herbivore-induced plant odorants and secondary metabolites in floral nectar in turn can affect moth behavior, and the underlying neural mechanisms. PMID:26321961

  3. Molecular taphonomy of animal and plant cuticles: selective preservation and diagenesis

    PubMed Central

    Briggs, D. E. G.

    1999-01-01

    The nature of organic material and the environment in which it is deposited exert a major influence on the extent to which biomacromolecules are preserved in the fossil record. The role of these factors is explored with a particular focus on the cuticle of arthropods and leaves. Preservation of the original chemistry of arthropod cuticles is favoured by their thickness and degree of sclerotization, and the presence of biominerals. Decay and burial in terrestrial as opposed to marine, and anoxic rather than oxygenated conditions, likewise appear to enhance preservation. The most important factor in the long-term preservation of the chemistry of both animal and plant cuticles, however, is diagenetic alteration to an aliphatic composition. This occurs even in amber, which encapsulates the fossil, eliminating almost all external factors. Some plants contain an original decay-resistant macromolecular aliphatic component but this is not the case in arthropods. It appears that the aliphatic components of many plant as well as animal fossils may be the result of diagenetic polymerization. Selective preservation as a result of decay resistance may explain the initial survival of organic materials in sediments, but in many cases longer-term preservation relies on chemical changes. Selective preservation is only a partial explanation for the origin of kerogen.

  4. North American Natural Gas Markets: Selected technical studies

    SciTech Connect

    Huntington, H.G.; Schuler, G.E.

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  5. North American Natural Gas Markets: Selected technical studies. Volume 3

    SciTech Connect

    Huntington, H.G.; Schuler, G.E.

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  6. Genes and Junk in Plant Mitochondria—Repair Mechanisms and Selection

    PubMed Central

    Christensen, Alan C.

    2014-01-01

    Plant mitochondrial genomes have very low mutation rates. In contrast, they also rearrange and expand frequently. This is easily understood if DNA repair in genes is accomplished by accurate mechanisms, whereas less accurate mechanisms including nonhomologous end joining or break-induced replication are used in nongenes. An important question is how different mechanisms of repair predominate in coding and noncoding DNA, although one possible mechanism is transcription-coupled repair (TCR). This work tests the predictions of TCR and finds no support for it. Examination of the mutation spectra and rates in genes and junk reveals what DNA repair mechanisms are available to plant mitochondria, and what selective forces act on the repair products. A model is proposed that mismatches and other DNA damages are repaired by converting them into double-strand breaks (DSBs). These can then be repaired by any of the DSB repair mechanisms, both accurate and inaccurate. Natural selection will eliminate coding regions repaired by inaccurate mechanisms, accounting for the low mutation rates in genes, whereas mutations, rearrangements, and expansions generated by inaccurate repair in noncoding regions will persist. Support for this model includes the structure of the mitochondrial mutS homolog in plants, which is fused to a double-strand endonuclease. The model proposes that plant mitochondria do not distinguish a damaged or mismatched DNA strand from the undamaged strand, they simply cut both strands and perform homology-based DSB repair. This plant-specific strategy for protecting future generations from mitochondrial DNA damage has the side effect of genome expansions and rearrangements. PMID:24904012

  7. Model operating permits for natural gas processing plants

    SciTech Connect

    Arend, C.

    1995-12-31

    Major sources as defined in Title V of the Clean Air Act Amendments of 1990 that are required to submit an operating permit application will need to: Evaluate their compliance status; Determine a strategic method of presenting the general and specific conditions of their Model Operating Permit (MOP); Maintain compliance with air quality regulations. A MOP is prepared to assist permitting agencies and affected facilities in the development of operating permits for a specific source category. This paper includes a brief discussion of example permit conditions that may be applicable to various types of Title V sources. A MOP for a generic natural gas processing plant is provided as an example. The MOP should include a general description of the production process and identify emission sources. The two primary elements that comprise a MOP are: Provisions of all existing state and/or local air permits; Identification of general and specific conditions for the Title V permit. The general provisions will include overall compliance with all Clean Air Act Titles. The specific provisions include monitoring, record keeping, and reporting. Although Title V MOPs are prepared on a case-by-case basis, this paper will provide a general guideline of the requirements for preparation of a MOP. Regulatory agencies have indicated that a MOP included in the Title V application will assist in preparation of the final permit provisions, minimize delays in securing a permit, and provide support during the public notification process.

  8. Tragedies and Crops: Understanding Natural Selection To Improve Cropping Systems.

    PubMed

    Anten, Niels P R; Vermeulen, Peter J

    2016-06-01

    Plant communities with traits that would maximize community performance can be invaded by plants that invest extra in acquiring resources at the expense of others, lowering the overall community performance, a so-called tragedy of the commons (TOC). By contrast, maximum community performance is usually the objective in agriculture. We first give an overview of the occurrence of TOCs in plants, and explore the extent to which past crop breeding has led to trait values that go against an unwanted TOC. We then show how linking evolutionary game theory (EGT) with mechanistic knowledge of the physiological processes that drive trait expression and the ecological aspects of biotic interactions in agro-ecosystems might contribute to increasing crop yields and resource-use efficiency. PMID:27012675

  9. Antitrypanosomal screening and cytotoxic effects of selected medicinal plants.

    PubMed

    Dyary, H O; Arifah, A K; Sharma, R S; Rasedee, A; Mohd-Aspollah, M S; Zakaria, Z A; Zuraini, A; Somchit, M N

    2014-03-01

    Trypanosoma evansi, the causative agent of "surra", infects many species of wild and domestic animals worldwide. In the current study, the aqueous and ethanolic extracts of six medicinal plants, namely, Aquilaria malaccensis, Derris elliptica, Garcinia hombroniana, Goniothalamus umbrosus, Nigella sativa, and Strobilanthes crispus were screened in vitro for activity against T. evansi. The cytotoxic activity of the extracts was evaluated on green monkey kidney (Vero) cells using MTT-cell proliferation assay. The median inhibitory concentrations (IC50) of the extracts ranged between 2.30 and 800.97 μg/ml and the median cytotoxic concentrations (CC50) ranged between 29.10 μg/ml and 14.53 mg/ml. The aqueous extract of G. hombroniana exhibited the highest selectivity index (SI) value of 616.36, followed by A. malaccensis aqueous extract (47.38). Phytochemical screening of the G. hombroniana aqueous extract revealed the presence of flavonoids, phenols, tannins, and saponins. It is demonstrated here that the aqueous extract of G. hombroniana has potential antitrypanosomal activity with a high SI, and may be considered as a potential source for the development of new antitrypanosomal compounds. PMID:24862048

  10. In vitro antitrypanosomal activity of ethnopharmacologically selected Beninese plants.

    PubMed

    Hoet, Sara; Opperdoes, Frederik; Brun, Reto; Adjakidjé, Victor; Quetin-Leclercq, Joëlle

    2004-03-01

    The in vitro antitrypanosomal activity of methylene chloride, methanol and aqueous extracts of the leaves and twigs of five plant species traditionally used in Benin for the treatment of sleeping sickness were evaluated on Trypanosoma brucei brucei and their selectivity was analysed on Leishmania mexicana mexicana and J774 macrophage-like murine cells. The results showed that the four most active extracts had MIC values < or =19 microg/ml (Hymenocardia acida twig and leaf, Strychnos spinosa leaf, Trichilia emetica leaf methylene chloride extracts). All these extracts had a lower activity on L. m. mexicana and J774 cells. Determination of the IC50 values of the methylene chloride leaf extracts on two strains of trypanosomes (T. b. brucei and T. b. rhodesiense) and two mammalian cell lines (L6 and J774 cells) showed that all extracts possessed some antitrypanosomal activity with IC50's ranging from 1.5 to 39 microg/ml. All were also toxic to the mammalian cells, but usually with higher IC50's. The only exception was the S. spinosa methylene chloride leaf extract which had no toxicity on J774 cells. Although tannins have been identified in most of the species studied, they could not be detected in the most active extracts, just as alkaloids. The presence of flavonoids and quinones may at least in part explain the observed activities of some of the active extracts. PMID:15036465

  11. Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students

    PubMed Central

    Kalinowski, Steven T.; Leonard, Mary J.; Andrews, Tessa M.; Litt, Andrea R.

    2013-01-01

    Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural selection and also include discussions on sexual selection, molecular evolution, evolution of complex traits, and the evolution of behavior. The set of six topics gives students the opportunity to see how natural selection operates in a variety of contexts. Pre- and postinstruction testing showed students’ understanding of natural selection increased substantially after completing this series of learning activities. Testing throughout this unit showed steadily increasing student understanding, and surveys indicated students enjoyed the activities. PMID:24006396

  12. Paternity and Nested-within-Family Marker Assisted Selection in Space Planted Red Clover Nurseries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Presented is a cost effective marker assisted selection methodology that utilizes individual plant phenotypes, seed production based knowledge of maternity, molecular marker determined paternity, and nested within halfsib family linkage relationships. Combining all above listed components, selection...

  13. Selected Common Poisonous Plants of the United States' Rangelands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poisonous plants cause large economic losses throughout the rangelands of the world. In the 17 western states of the United States alone, it has been estimated that losses related to the ingestion of poisonous plants exceed $340 million annually. There are many plants that contribute to these large...

  14. Accumulation of mercury in selected plant species grown in soils contaminated with different mercury compounds

    SciTech Connect

    Su, Yi; Han, Fengxiang; Shiyab, Safwan; Chen, Jian; Monts, David L.

    2007-07-01

    The objective of our research is to screen and search for suitable plant species for phyto-remediation of mercury-contaminated soil. Currently our effort is specifically focused on mercury removal from the U.S. Department of Energy (DOE) sites, where mercury contamination is a major concern. In order to cost effectively implement mercury remediation efforts, it is necessary now to obtain an improved understanding of biological means of removing mercury and mercury compounds.. Phyto-remediation is a technology that uses various plants to degrade, extract, contain, or immobilize contaminants from soil and water. In particular, phyto-extraction is the uptake of contaminants by plant roots and translocation within the plants to shoots or leaves. Contaminants are generally removed by harvesting the plants. We have investigated phyto-extraction of mercury from contaminated soil by using some of the known metal-accumulating plants since no natural plant species with mercury hyper-accumulating properties has yet been identified. Different natural plant species have been studied for mercury uptake, accumulation, toxicity and overall mercury removal efficiency. Various mercury compounds, such as HgS, HgCl{sub 2}, and Hg(NO{sub 3}){sub 2}, were used as contaminant sources. Different types of soil were examined and chosen for phyto-remediation experiments. We have applied microscopy and diffuse reflectance spectrometry as well as conventional analytical chemistry to monitor the phyto-remediation processes of mercury uptake, translocation and accumulation, and the physiological impact of mercury contaminants on selected plant species. Our results indicate that certain plant species, such as beard grass (Polypogon monospeliensis), accumulated a very limited amount of mercury in the shoots (<65 mg/kg), even though root mercury accumulation is significant (maximum 2298 mg/kg). Consequently, this plant species may not be suitable for mercury phyto-remediation. Other plant species

  15. Natural Selection in Virulence Genes of Francisella tularensis.

    PubMed

    Gunnell, Mark K; Robison, Richard A; Adams, Byron J

    2016-06-01

    A fundamental tenet of evolution is that alleles that are under negative selection are often deleterious and confer no evolutionary advantage. Negatively selected alleles are removed from the gene pool and are eventually extinguished from the population. Conversely, alleles under positive selection do confer an evolutionary advantage and lead to an increase in the overall fitness of the organism. These alleles increase in frequency until they eventually become fixed in the population. Francisella tularensis is a zoonotic pathogen and a potential biothreat agent. The most virulent type of F. tularensis, Type A, is distributed across North America with Type A.I occurring mainly in the east and Type A.II appearing mainly in the west. F. tularensis is thought to be a genome in decay (losing genes) because of the relatively large number of pseudogenes present in its genome. We hypothesized that the observed frequency of gene loss/pseudogenes may be an artifact of evolution in response to a changing environment, and that genes involved in virulence should be under strong positive selection. To test this hypothesis, we sequenced and compared whole genomes of Type A.I and A.II isolates. We analyzed a subset of virulence and housekeeping genes from several F. tularensis subspecies genomes to ascertain the presence and extent of positive selection. Eleven previously identified virulence genes were screened for positive selection along with 10 housekeeping genes. Analyses of selection yielded one housekeeping gene and 7 virulence genes which showed significant evidence of positive selection at loci implicated in cell surface structures and membrane proteins, metabolism and biosynthesis, transcription, translation and cell separation, and substrate binding and transport. Our results suggest that while the loss of functional genes through disuse could be accelerated by negative selection, the genome decay in Francisella could also be the byproduct of adaptive evolution

  16. Nutritional and cultural aspects of plant species selection for a controlled ecological life support system

    NASA Technical Reports Server (NTRS)

    Hoff, J. E.; Howe, J. M.; Mitchell, C. A.

    1982-01-01

    The feasibility of using higher plants in a controlled ecological life support system is discussed. Aspects of this system considered important in the use of higher plants include: limited energy, space, and mass, and problems relating to cultivation and management of plants, food processing, the psychological impact of vegetarian diets, and plant propagation. A total of 115 higher plant species are compared based on 21 selection criteria.

  17. Traditional knowledge of medicinal plants in the Serra de Mariola Natural Park, South-Eastern Spain.

    PubMed

    Belda, A; Zaragozí, B; Belda, I; Martínez, Je; Seva, E

    2013-01-01

    The present study aims to inventory and analyse the ethnobotanical knowledge about medicinal plants in the Serra de Mariola Natural Park. In respect to traditional uses, 93 species reported by local informants were therapeutic, 27 food, 4 natural dyes and 13 handcrafts. We developed a methodology that allowed the location of individuals or vegetation communities with a specific popular use. We prepared a geographic information system (GIS) that included gender, family, scientific nomenclature and common names in Spanish and Catalan for each species. We also made a classification of 39 medicinal uses from ATC (Anatomical, Therapeutic, Chemical classification system). Labiatae (n=19), Compositae (n=9) and Leguminosae (n=6) were the families most represented among the plants used to different purposes in humans. Species with the most elevated cultural importance index (CI) values were Thymus vulgaris (CI=1.431), Rosmarinus officinalis (CI=1.415), Eryngium campestre (CI=1.325), Verbascum sinuatum (CI=1.106) and Sideritis angustifolia (CI=1.041). Thus, the collected plants with more therapeutic uses were: Lippia triphylla (12), Thymus vulgaris and Allium roseum (9) and Erygium campestre (8). The most repeated ATC uses were: G04 (urological use), D03 (treatment of wounds and ulcers) and R02 (throat diseases). These results were in a geographic map where each point represented an individual of any species. A database was created with the corresponding therapeutic uses. This application is useful for the identification of individuals and the selection of species for specific medicinal properties. In the end, knowledge of these useful plants may be interesting to revive the local economy and in some cases promote their cultivation. PMID:24146454

  18. Spatial patterns of variation due to natural selection in humans

    PubMed Central

    Novembre, John; Di Rienzo, Anna

    2013-01-01

    Empowered by technology and sampling efforts designed to facilitate genome-wide association mapping, human geneticists are now studying the geography of genetic variation with unprecedented detail. With high genomic coverage and geographic resolution, these studies are identifying loci with spatial signatures of selection, such as extreme levels of differentiation and correlations with environmental variables. Collectively, patterns at these loci are beginning to provide novel insights into the process of human adaptation. Here we review the challenges of these studies and emerging results, including how human population structure has influenced the response to novel selective pressures. PMID:19823195

  19. Teaching Evolution and Natural Selection: A Look at Textbooks and Teachers.

    ERIC Educational Resources Information Center

    Aleixandre, Maria Pilar Jimenez

    1994-01-01

    Contrasts data gathered regarding how textbooks deal with natural selection and teacher's ability to explore pupils' ideas related to it with an approach seeking to develop the pupils' capacity to explain biological change using the model of natural selection. Results show the approach is often characterized by superficial handling of key ideas…

  20. A Hands-On Exercise to Demonstrate Evolution by Natural Selection & Genetic Drift

    ERIC Educational Resources Information Center

    Young, Helen J.; Young, Truman P.

    2003-01-01

    Although students "learn" (i.e., hear about) the components of evolution by natural selection in high school biology courses, few of them truly understand or remember them. Evolution by natural selection, although seemingly simple, requires that several conditions be met. The trait of concern must exhibit variation within the population; this…

  1. Evolution of Students' Ideas about Natural Selection through a Constructivist Framework

    ERIC Educational Resources Information Center

    Baumgartner, Erin; Duncan, Kanesa

    2009-01-01

    Educating students about the process of evolution through natural selection is vitally important because not only is it the unifying theory of biological science, it is also widely regarded as difficult for students to fully comprehend. Anderson and colleagues (2002) describe alternative ideas and misconceptions about natural selection as highly…

  2. Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students

    ERIC Educational Resources Information Center

    Kalinowski, Steven T.; Leonard, Mary J.; Andrews, Tessa M.; Litt, Andrea R.

    2013-01-01

    Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural…

  3. Conservation of endangered Lupinus mariae-josephae in its natural habitat by inoculation with selected, native Bradyrhizobium strains.

    PubMed

    Navarro, Albert; Fos, Simón; Laguna, Emilio; Durán, David; Rey, Luis; Rubio-Sanz, Laura; Imperial, Juan; Ruiz-Argüeso, Tomás

    2014-01-01

    Lupinus mariae-josephae is a recently discovered endemism that is only found in alkaline-limed soils, a unique habitat for lupines, from a small area in Valencia region (Spain). In these soils, L. mariae-josephae grows in just a few defined patches, and previous conservation efforts directed towards controlled plant reproduction have been unsuccessful. We have previously shown that L. mariae-josephae plants establish a specific root nodule symbiosis with bradyrhizobia present in those soils, and we reasoned that the paucity of these bacteria in soils might contribute to the lack of success in reproducing plants for conservation purposes. Greenhouse experiments using L. mariae-josephae trap-plants showed the absence or near absence of L. mariae-josephae-nodulating bacteria in "terra rossa" soils of Valencia outside of L. mariae-josephae plant patches, and in other "terra rossa" or alkaline red soils of the Iberian Peninsula and Balearic Islands outside of the Valencia L. mariae-josephae endemism region. Among the bradyrhizobia able to establish an efficient symbiosis with L. mariae-josephae plants, two strains, LmjC and LmjM3 were selected as inoculum for seed coating. Two planting experiments were carried out in consecutive years under natural conditions in areas with edapho-climatic characteristics identical to those sustaining natural L. mariae-josephae populations, and successful reproduction of the plant was achieved. Interestingly, the successful reproductive cycle was absolutely dependent on seedling inoculation with effective bradyrhizobia, and optimal performance was observed in plants inoculated with LmjC, a strain that had previously shown the most efficient behavior under controlled conditions. Our results define conditions for L. mariae-josephae conservation and for extension to alkaline-limed soil habitats, where no other known lupine can thrive. PMID:25019379

  4. Conservation of Endangered Lupinus mariae-josephae in Its Natural Habitat by Inoculation with Selected, Native Bradyrhizobium Strains

    PubMed Central

    Navarro, Albert; Fos, Simón; Laguna, Emilio; Durán, David; Rey, Luis; Rubio-Sanz, Laura; Imperial, Juan; Ruiz-Argüeso, Tomás

    2014-01-01

    Lupinus mariae-josephae is a recently discovered endemism that is only found in alkaline-limed soils, a unique habitat for lupines, from a small area in Valencia region (Spain). In these soils, L. mariae-josephae grows in just a few defined patches, and previous conservation efforts directed towards controlled plant reproduction have been unsuccessful. We have previously shown that L. mariae-josephae plants establish a specific root nodule symbiosis with bradyrhizobia present in those soils, and we reasoned that the paucity of these bacteria in soils might contribute to the lack of success in reproducing plants for conservation purposes. Greenhouse experiments using L. mariae-josephae trap-plants showed the absence or near absence of L. mariae-josephae-nodulating bacteria in “terra rossa” soils of Valencia outside of L. mariae-josephae plant patches, and in other “terra rossa” or alkaline red soils of the Iberian Peninsula and Balearic Islands outside of the Valencia L. mariae-josephae endemism region. Among the bradyrhizobia able to establish an efficient symbiosis with L. mariae-josephae plants, two strains, LmjC and LmjM3 were selected as inoculum for seed coating. Two planting experiments were carried out in consecutive years under natural conditions in areas with edapho-climatic characteristics identical to those sustaining natural L. mariae-josephae populations, and successful reproduction of the plant was achieved. Interestingly, the successful reproductive cycle was absolutely dependent on seedling inoculation with effective bradyrhizobia, and optimal performance was observed in plants inoculated with LmjC, a strain that had previously shown the most efficient behavior under controlled conditions. Our results define conditions for L. mariae-josephae conservation and for extension to alkaline-limed soil habitats, where no other known lupine can thrive. PMID:25019379

  5. Selected References on Asbestos: Its Nature, Hazards, Detection, and Control.

    ERIC Educational Resources Information Center

    National Education Association, Washington, DC.

    This document provides teachers with sources of information about the nature, hazards, detection, and control of asbestos. Because many school buildings include asbestos-containing materials, teachers and other school personnel must be aware of the potential dangers to students and to themselves and take steps to have asbestos hazards contained or…

  6. Evolutionary stasis in pollen morphogenesis due to natural selection.

    PubMed

    Matamoro-Vidal, Alexis; Prieu, Charlotte; Furness, Carol A; Albert, Béatrice; Gouyon, Pierre-Henri

    2016-01-01

    The contribution of developmental constraints and selective forces to the determination of evolutionary patterns is an important and unsolved question. We test whether the long-term evolutionary stasis observed for pollen morphogenesis (microsporogenesis) in eudicots is due to developmental constraints or to selection on a morphological trait shaped by microsporogenesis: the equatorial aperture pattern. Most eudicots have three equatorial apertures but several taxa have independently lost the equatorial pattern and have microsporogenesis decoupled from aperture pattern determination. If selection on the equatorial pattern limits variation, we expect to see increased variation in microsporogenesis in the nonequatorial clades. Variation of microsporogenesis was studied using phylogenetic comparative analyses in 83 species dispersed throughout eudicots including species with and without equatorial apertures. The species that have lost the equatorial pattern have highly variable microsporogenesis at the intra-individual and inter-specific levels regardless of their pollen morphology, whereas microsporogenesis remains stable in species with the equatorial pattern. The observed burst of variation upon loss of equatorial apertures shows that there are no strong developmental constraints precluding variation in microsporogenesis, and that the stasis is likely to be due principally to selective pressure acting on pollen morphogenesis because of its implication in the determination of the equatorial aperture pattern. PMID:26248868

  7. Food plant derived disease tolerance and resistance in a natural butterfly-plant-parasite interactions.

    PubMed

    Sternberg, Eleanore D; Lefèvre, Thierry; Li, James; de Castillejo, Carlos Lopez Fernandez; Li, Hui; Hunter, Mark D; de Roode, Jacobus C

    2012-11-01

    Organisms can protect themselves against parasite-induced fitness costs through resistance or tolerance. Resistance includes mechanisms that prevent infection or limit parasite growth while tolerance alleviates the fitness costs from parasitism without limiting infection. Although tolerance and resistance affect host-parasite coevolution in fundamentally different ways, tolerance has often been ignored in animal-parasite systems. Where it has been studied, tolerance has been assumed to be a genetic mechanism, unaffected by the host environment. Here we studied the effects of host ecology on tolerance and resistance to infection by rearing monarch butterflies on 12 different species of milkweed food plants and infecting them with a naturally occurring protozoan parasite. Our results show that monarch butterflies experience different levels of tolerance to parasitism depending on the species of milkweed that they feed on, with some species providing over twofold greater tolerance than other milkweed species. Resistance was also affected by milkweed species, but there was no relationship between milkweed-conferred resistance and tolerance. Chemical analysis suggests that infected monarchs obtain highest fitness when reared on milkweeds with an intermediate concentration, diversity, and polarity of toxic secondary plant chemicals known as cardenolides. Our results demonstrate that environmental factors-such as interacting species in ecological food webs-are important drivers of disease tolerance. PMID:23106703

  8. Physico-chemical change and heat stability of extra virgin olive oils flavoured by selected Tunisian aromatic plants.

    PubMed

    Ayadi, M A; Grati-Kamoun, N; Attia, H

    2009-10-01

    Objectives of this work were studying physico-chemical change and heat stability of olive oils flavoured by selected Tunisian aromatic plants. Flavoured olive oils were prepared by maceration of fresh plant materials (rosemary, lavender, sage, menthe, basil, lemon and thyme) with olive oil at a 5% w/w level for 15 days. A sensorial evaluation was applied to select more appreciate flavoured olive oils by consumers. An oxidative procedure was applied to test the stability of selected flavoured olive oils: oils samples were kept in glass bottles and heated at 60 and 130 degrees C during 55 days and 6h, respectively. The resistance to oxidation of these selected flavoured oils was compared to a control samples by measuring PV, K232 and K270 values and change in chlorophyll, carotenes and polyphénols contents. Obtained results show that addition of aromatic plants causes a slight increase in free acidity and viscosity of aromatised olive oils. L*, b* and a* values show that addition of thyme cause a great change in olive oil colours. Heat stability results shows that from selected aromatic plants, rosemary was effectiveness against oxidation followed by thyme and lemon. However, olive oil flavoured with basil exhibit a similar behaviour versus thermal oxidation then the natural olive oil. PMID:19635520

  9. Biometric approach in selecting plants for phytoaccumulation of uranium.

    PubMed

    Stojanović, Mirjana; Pezo, Lato; Lačnjevac, Časlav; Mihajlović, Marija; Petrović, Jelena; Milojković, Jelena; Stanojević, Marija

    2016-01-01

    This paper promotes the biometric classification system of plant cultivars, unique characteristics, in terms of the uranium (U) uptake, primarily in the function of the application for phytoremediation. It is known that the degree of adoption of U depends on the plant species and its morphological and physiological properties, but it is less known what impact have plants cultivars, sorts, and hybrids. Therefore, we investigated the U adoption in four cultivars of three plant species (corn, sunflower and soy bean). "Vegetation experiments were carried out in a plastic-house filled with soil (0.66 mgU) and with tailing (15.3 mgU kg(-1)) from closed uranium mine Gabrovnica-Kalna southeast of Serbia". Principal Component Analysis (PCA), Cluster Analysis (CA) and analysis of variance (ANOVA) were used for assessing the effect of different substrates cultivars, plant species and plant organs (root or shoot) on U uptake. Obtained results showed that a difference in U uptake by three investigated plant species depends not only of the type of substrate types and plant organs but also of their cultivars. Biometrics techniques provide a good opportunity for a better understanding the behavior of plants and obtaining much more useful information from the original data. PMID:26606604

  10. Predation and selection for antibiotic resistance in natural environments.

    PubMed

    Leisner, Jørgen J; Jørgensen, Niels O G; Middelboe, Mathias

    2016-03-01

    Genes encoding resistance to antibiotics appear, like the antibiotics themselves, to be ancient, originating long before the rise of the era of anthropogenic antibiotics. However, detailed understanding of the specific biological advantages of antibiotic resistance in natural environments is still lacking, thus limiting our efforts to prevent environmental influx of resistance genes. Here, we propose that antibiotic-resistant cells not only evade predation from antibiotic producers but also take advantage of nutrients released from cells that are killed by the antibiotic-producing bacteria. Thus, predation is potentially an important mechanism for driving antibiotic resistance during slow or stationary phase of growth when nutrients are deprived. This adds to explain the ancient nature and widespread occurrence of antibiotic resistance in natural environments unaffected by anthropogenic antibiotics. In particular, we suggest that nutrient-poor environments including indoor environments, for example, clean rooms and intensive care units may serve as a reservoir and source for antibiotic-producing as well as antibiotic-resistant bacteria. PMID:26989434

  11. Natural selection of mitochondria during somatic lifetime promotes healthy aging

    PubMed Central

    Rodell, Anders; Rasmussen, Lene J.; Bergersen, Linda H.; Singh, Keshav K.; Gjedde, Albert

    2013-01-01

    Stimulation of mitochondrial biogenesis during life-time challenges both eliminates disadvantageous properties and drives adaptive selection of advantageous phenotypic variations. Intermittent fission and fusion of mitochondria provide specific targets for health promotion by brief temporal stressors, interspersed with periods of recovery and biogenesis. For mitochondria, the mechanisms of selection, variability, and heritability, are complicated by interaction of two independent genomes, including the multiple copies of DNA in each mitochondrion, as well as the shared nuclear genome of each cell. The mechanisms of stress-induced fission, followed by recovery-induced fusion and biogenesis, drive the improvement of mitochondrial functions, not only as directed by genotypic variations, but also as enabled by phenotypic diversity. Selective adaptation may explain unresolved aspects of aging, including the health effects of exercise, hypoxic and poisonous preconditioning, and tissue-specific mitochondrial differences. We propose that intermittent purposeful enhancement of mitochondrial biogenesis by stressful episodes with subsequent recovery paradoxically promotes adaptive mitochondrial health and continued healthy aging. PMID:23964235

  12. Anthocyanins: Analysis and Distribution in Selected Medicinal Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anthocyanins are water soluble plant secondary metabolites responsible for the blue, purple, and red color of many plant tissues. They have been shown to be strong antioxidants, and may exert a wide range of health benefits through antioxidant or other mechanisms. Anthocyanins occur primarily as gly...

  13. Anthocyanins: analysis and distribution in selected medicinal plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anthocyanins are water soluble plant secondary metabolites responsible for the blue, purple, and red color of many plant tissues. They have been shown to be strong antioxidants, and may exert a wide range of health benefits through antioxidant or other mechanisms. Anthocyanins occur primarily as g...

  14. Selection of an acid-gas removal process for an LNG plant

    SciTech Connect

    Stone, J.B.; Jones, G.N.; Denton, R.D.

    1996-12-31

    Acid gas contaminants, such as, CO{sub 2}, H{sub 2}S and mercaptans, must be removed to a very low level from a feed natural gas before it is liquefied. CO{sub 2} is typically removed to a level of about 100 ppm to prevent freezing during LNG processing. Sulfur compounds are removed to levels required by the eventual consumer of the gas. Acid-gas removal processes can be broadly classified as: solvent-based, adsorption, cryogenic or physical separation. The advantages and disadvantages of these processes will be discussed along with design and operating considerations. This paper will also discuss the important considerations affecting the choice of the best acid-gas removal process for LNG plants. Some of these considerations are: the remoteness of the LNG plant from the resource; the cost of the feed gas and the economics of minimizing capital expenditures; the ultimate disposition of the acid gas; potential for energy integration; and the composition, including LPG and conditions of the feed gas. The example of the selection of the acid-gas removal process for an LNG plant.

  15. Natural selection of altruism in inelastic viscous homogeneous populations.

    PubMed

    Grafen, Alan; Archetti, Marco

    2008-06-21

    Biological explanations are given of three main uninterpreted theoretical results on the selection of altruism in inelastic viscous homogeneous populations, namely that non-overlapping generations hinder the evolution of altruism, fecundity effects are more conducive to altruism than survival effects, and one demographic regime (so-called death-birth) permits altruism whereas another (so-called birth-death) does not. The central idea is 'circles of compensation', which measure how far the effects of density dependence extend from a focal individual. Relatednesses can then be calculated that compensate for density dependence. There is very generally a 'balancing circle of compensation', at which the viscosity of the population slows up selection of altruism, but does not affect its direction, and this holds for altruism towards any individual, not just immediate neighbours. These explanations are possible because of recent advances in the theory of inclusive fitness on graphs. The assumption of node bitransitivity in that recent theory is relaxed to node transitivity and symmetry of the dispersal matrix, and new formulae show how to calculate relatedness from dispersal and vice versa. PMID:18371985

  16. Selective looking at natural scenes: Hedonic content and gender.

    PubMed

    Bradley, Margaret M; Costa, Vincent D; Lang, Peter J

    2015-10-01

    Choice viewing behavior when looking at affective scenes was assessed to examine differences due to hedonic content and gender by monitoring eye movements in a selective looking paradigm. On each trial, participants viewed a pair of pictures that included a neutral picture together with an affective scene depicting either contamination, mutilation, threat, food, nude males, or nude females. The duration of time that gaze was directed to each picture in the pair was determined from eye fixations. Results indicated that viewing choices varied with both hedonic content and gender. Initially, gaze duration for both men and women was heightened when viewing all affective contents, but was subsequently followed by significant avoidance of scenes depicting contamination or nude males. Gender differences were most pronounced when viewing pictures of nude females, with men continuing to devote longer gaze time to pictures of nude females throughout viewing, whereas women avoided scenes of nude people, whether male or female, later in the viewing interval. For women, reported disgust of sexual activity was also inversely related to gaze duration for nude scenes. Taken together, selective looking as indexed by eye movements reveals differential perceptual intake as a function of specific content, gender, and individual differences. PMID:26156939

  17. Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

    PubMed Central

    Sakkas, Denny; Ramalingam, Mythili; Garrido, Nicolas; Barratt, Christopher L.R.

    2015-01-01

    BACKGROUND In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART. METHODS A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented. RESULTS AND CONCLUSIONS New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo. PMID:26386468

  18. A force of nature: molecular mechanisms of mechanoperception in plants

    PubMed Central

    Haswell, Elizabeth S.

    2013-01-01

    The ability to sense and respond to a wide variety of mechanical stimuli—gravity, touch, osmotic pressure, or the resistance of the cell wall—is a critical feature of every plant cell, whether or not it is specialized for mechanotransduction. Mechanoperceptive events are an essential part of plant life, required for normal growth and development at the cell, tissue, and whole-plant level and for the proper response to an array of biotic and abiotic stresses. One current challenge for plant mechanobiologists is to link these physiological responses to specific mechanoreceptors and signal transduction pathways. Here, we describe recent progress in the identification and characterization of two classes of putative mechanoreceptors, ion channels and receptor-like kinases. We also discuss how the secondary messenger Ca2+ operates at the centre of many of these mechanical signal transduction pathways. PMID:23913953

  19. A selective and mild glycosylation method of natural phenolic alcohols

    PubMed Central

    Poláková, Monika

    2016-01-01

    Summary Several bioactive natural p-hydroxyphenylalkyl β-D-glucopyranosides, such as vanillyl β-D-glucopyranoside, salidroside and isoconiferin, and their glycosyl analogues were prepared by a simple reaction sequence. The highly efficient synthetic approach was achieved by utilizing acetylated glycosyl bromides as well as aromatic moieties and mild glycosylation promoters. The aglycones, p-O-acetylated arylalkyl alcohols, were prepared by the reduction of the corresponding acetylated aldehydes or acids. Various stereoselective 1,2-trans-O-glycosylation methods were studied, including the DDQ–iodine or ZnO–ZnCl2 catalyst combination. Among them, ZnO–iodine has been identified as a new glycosylation promoter and successfully applied to the stereoselective glycoside synthesis. The final products were obtained by conventional Zemplén deacetylation. PMID:27340444

  20. Natural selectivity of Nickel and Vanadium in crude oil

    NASA Astrophysics Data System (ADS)

    Fernandez, Olienka Patricia De La O.

    Nickel and Vanadium have always been found in crude oil all around the world. The metal content is found mainly in porphyrin structures in the asphaltene fraction of the petroleum. In order to determine the reason for this natural preference, a set of experiments testing thermodynamics, kinetics, and other factors were performed. Candidate metalloporphyrins containing Vanadyl, Chromium, Iron, Nickel, Copper and Zinc were analyzed through chemical reactions characterized using Silica Column Chromatography, HPLC, MS and UV-Visible. Theoretical analysis of the stability of metalloporphyrins was conducted using DFT/NRLMOL for computational calculation. The analysis of all factors leads us to conclude that the presence of Nickel and Vanadium in petroleum depend on different factors, not only on the stability of the structures, but mainly on abundance in the medium rising from biological processes.

  1. Affective Neuronal Selection: The Nature of the Primordial Emotion Systems

    PubMed Central

    Toronchuk, Judith A.; Ellis, George F. R.

    2013-01-01

    Based on studies in affective neuroscience and evolutionary psychiatry, a tentative new proposal is made here as to the nature and identification of primordial emotional systems. Our model stresses phylogenetic origins of emotional systems, which we believe is necessary for a full understanding of the functions of emotions and additionally suggests that emotional organizing systems play a role in sculpting the brain during ontogeny. Nascent emotional systems thus affect cognitive development. A second proposal concerns two additions to the affective systems identified by Panksepp. We suggest there is substantial evidence for a primary emotional organizing program dealing with power, rank, dominance, and subordination which instantiates competitive and territorial behavior and is an evolutionary contributor to self-esteem in humans. A program underlying disgust reactions which originally functioned in ancient vertebrates to protect against infection and toxins is also suggested. PMID:23316177

  2. Developments of the Price equation and natural selection under uncertainty.

    PubMed

    Grafen, A

    2000-06-22

    Many approaches to the study of adaptation, following Darwin, centre on the number of offspring of individuals. Population genetics theory makes clear that predicting gene frequency changes requires more detailed knowledge, for example of linkage and linkage disequilibrium and mating systems. Because gene frequency changes underlie adaptation, this can lead to a suspicion that approaches ignoring these sophistications are approximate or tentative or wrong. Stochastic environments and sexual selection are two topics in which there are widespread views that focusing on number of offspring of individuals is not enough, and that proper treatments require the introduction of further details, namely variability in offspring number and linkage disequilibrium, respectively. However, the bulk of empirical research on adaptation and a great deal of theoretical work continue to employ these approaches. Here, a new theoretical development arising from the Price equation provides a formal justification in very general circumstances for focusing on the arithmetic average of the relative number of offspring of individuals. PMID:10902688

  3. Nutrient composition of selected traditional native American plant foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ten wild plants (cattail narrow leaf shoots, chokecherries, beaked hazelnuts, lambsquarters, plains pricklypear, prairie turnips, stinging nettles, wild plums, raspberries, rose hips) from three Native American reservations in North Dakota were analyzed to expand composition information of tradition...

  4. The Nature of Irac-selected Extremely Red Objects

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Huang, J.; Gu, Q.

    2010-05-01

    Using deep U-8um photometry from GEMs, MUSYC and SIMPLE surveys, we investigate properties of a large sample of IRAC-selected extremely red galaxies(IEROs). The sample comprises 304 brightest IEROs distributed over the GEMS field with a total area of 800 arcmin2, which satisfy ([3.6]+[4.5]/2)<21.2 and z-[3.6] > 3.25). Combined with the deepest Chandra and Spitzer surveys in this field, we are able to determine relative contributions of AGNs, (dusty) star-forming galaxies and passively evolving systems to the RED population; 51 sources are detected in at least one of three X-ray bands, leaving 253 non-Xray sources with 179 detected in 24um( 20uJy, 3sigma), indicating that at most 25% of these IEROs are passively evolving.We derive and examine photometric redshift using different methods; their redshift range from 1 to 2.6 with the median value at 1.5. Stellar masses of non-Xray sources are also derived with SED fitting methods, achieving a median value of 0.4*1011 Msun for a chrabrier initial mass function. The properties of best-fitting BC03 models are consistent with templates used for estimating redshifts, which have on average E(B-V) of 0.5 for 24um-deteced galaxies. The corresponding star-formation rates of these star-forming galaxies through SED fitting are within 40-100 Msun yr-1, consistent with that derived from their 24μm flux, which show a median total infrared luminosity 1*1011Lsun. We argue that such selected IEROs may represent a transient population from ULIRGs to LIRGs, and are likely descents of SMGs or DOGs.

  5. Selective isolation of components from natural volatile oil by countercurrent chromatography with cyclodextrins as selective reagent.

    PubMed

    Tong, Shengqiang; Lu, Mengxia; Chu, Chu; Yan, Jizhong; Huang, Juan; Ying, Yongfei

    2016-04-29

    Selective separation of chemical components from seven kinds of volatile oil by countercurrent chromatography with three types of cyclodextrins as selective reagent was investigated in this work. Preparative separation of chemical components from volatile oil is generally quite challenging due to their extremely complexity of the composition. A biphasic solvent system n-hexane-0.10molL(-1) cyclodextrin (1:1, v/v) was selected for separation of components from volatile oil and three types of cyclodextrins were investigated, including β-cyclodexrin, methyl-β-cyclodexrin and hydroxypropyl-β-cyclodexrin. All kinds of volatile oils are from seven kinds of traditional Chinese herb. Results showed that some chemical components could be well separated with high purity from each kind of volatile oil using different type of cyclodextrin as selective reagent. For example, germacrone and curcumenone could be selectively separated from volatile oil of Curcumae Rhizoma with methyl-β-cyclodexrin and hydroxypropyl-β-cyclodexrin as selector respectively, and other five components were selectively separated from volatile oil of Chuanxiong Rhizoma, Myristicae Semen, Aucklandiae Radix and Angelicae Sinensis Radix by countercurrent chromatography with different cyclodexrin as selective reagent. Separation mechanism for separation of components from volatile oil by countercurrent chromatography with cyclodextrin as selective reagent was proposed. Peak resolution of the present separation method could be greatly influenced by the chemical compositions of volatile oil. PMID:27036211

  6. Natural toxins that affect plant amino acid metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A diverse range of natural compounds interfere with the synthesis and other aspects of amino acid metabolism. Some are amino acid analogues, but most are not. This review covers a number of specific natural phytotoxic compounds by molecular target site. Inhibition of glutamine synthetase is of part...

  7. Climate change may threaten habitat suitability of threatened plant species within Chinese nature reserves

    PubMed Central

    Wan, Jizhong

    2016-01-01

    Climate change has the potential to alter the distributions of threatened plant species, and may therefore diminish the capacity of nature reserves to protect threatened plant species. Chinese nature reserves contain a rich diversity of plant species that are at risk of becoming more threatened by climate change. Hence, it is urgent to identify the extent to which future climate change may compromise the suitability of threatened plant species habitats within Chinese nature reserves. Here, we modelled the climate suitability of 82 threatened plant species within 168 nature reserves across climate change scenarios. We used Maxent modelling based on species occurrence localities and evaluated climate change impacts using the magnitude of change in climate suitability and the degree of overlap between current and future climatically suitable habitats. There was a significant relationship between overlap with current and future climate suitability of all threatened plant species habitats and the magnitude of changes in climate suitability. Our projections estimate that the climate suitability of more than 60 threatened plant species will decrease and that climate change threatens the habitat suitability of plant species in more than 130 nature reserves under the low, medium, and high greenhouse gas concentration scenarios by both 2050s and 2080s. Furthermore, future climate change may substantially threaten tree plant species through changes in annual mean temperature. These results indicate that climate change may threaten plant species that occur within Chinese nature reserves. Therefore, we suggest that climate change projections should be integrated into the conservation and management of threatened plant species within nature reserves. PMID:27326373

  8. Natural compounds isolated from Brazilian plants are potent inhibitors of hepatitis C virus replication in vitro

    PubMed Central

    Jardim, A.C.G.; Igloi, Z.; Shimizu, J.F.; Santos, V.A.F.F.M.; Felippe, L.G.; Mazzeu, B.F.; Amako, Y.; Furlan, M.; Harris, M.; Rahal, P.

    2015-01-01

    Compounds extracted from plants can provide an alternative approach to new therapies. They present characteristics such as high chemical diversity, lower cost of production and milder or inexistent side effects compared with conventional treatment. The Brazilian flora represents a vast, largely untapped, resource of potential antiviral compounds. In this study, we investigate the antiviral effects of a panel of natural compounds isolated from Brazilian plants species on hepatitis C virus (HCV) genome replication. To do this we used firefly luciferase-based HCV sub-genomic replicons of genotypes 2a (JFH-1), 1b and 3a and the compounds were assessed for their effects on both HCV replication and cellular toxicity. Initial screening of compounds was performed using the maximum non-toxic concentration and 4 compounds that exhibited a useful therapeutic index (favourable ratio of cytotoxicity to antiviral potency) were selected for extra analysis. The compounds APS (EC50 = 2.3 μM), a natural alkaloid isolated from Maytrenus ilicifolia, and the lignans 3∗43 (EC50 = 4.0 μM), 3∗20 (EC50 = 8.2 μM) and 5∗362 (EC50 = 38.9 μM) from Peperomia blanda dramatically inhibited HCV replication as judged by reductions in luciferase activity and HCV protein expression in both the subgenomic and infectious systems. We further show that these compounds are active against a daclatasvir resistance mutant subgenomic replicon. Consistent with inhibition of genome replication, production of infectious JFH-1 virus was significantly reduced by all 4 compounds. These data are the first description of Brazilian natural compounds possessing anti-HCV activity and further analyses are being performed in order to investigate the mode of action of those compounds. PMID:25557602

  9. Predicting in silico which mixtures of the natural products of plants might most effectively kill human leukemia cells?

    PubMed

    El-Shemy, Hany A; Aboul-Enein, Khalid M; Lightfoot, David A

    2013-01-01

    The aim of the analysis of just 13 natural products of plants was to predict the most likely effective artificial mixtures of 2-3 most effective natural products on leukemia cells from over 364 possible mixtures. The natural product selected included resveratrol, honokiol, chrysin, limonene, cholecalciferol, cerulenin, aloe emodin, and salicin and had over 600 potential protein targets. Target profiling used the Ontomine set of tools for literature searches of potential binding proteins, binding constant predictions, binding site predictions, and pathway network pattern analysis. The analyses indicated that 6 of the 13 natural products predicted binding proteins which were important targets for established cancer treatments. Improvements in effectiveness were predicted for artificial combinations of 2 or 3 natural products. That effect might be attributed to drug synergism rather than increased numbers of binding proteins bound (dose effects). Among natural products, the combinations of aloe emodin with mevinolin and honokiol were predicted to be the most effective combination for AML-related predicted binding proteins. Therefore, plant extracts may in future provide more effective medicines than the single purified natural products of modern medicine, in some cases. PMID:23431350

  10. Salicornia strobilacea (Synonym of Halocnemum strobilaceum) Grown under Different Tidal Regimes Selects Rhizosphere Bacteria Capable of Promoting Plant Growth

    PubMed Central

    Marasco, Ramona; Mapelli, Francesca; Rolli, Eleonora; Mosqueira, Maria J.; Fusi, Marco; Bariselli, Paola; Reddy, Muppala; Cherif, Ameur; Tsiamis, George; Borin, Sara; Daffonchio, Daniele

    2016-01-01

    Halophytes classified under the common name of salicornia colonize salty and coastal environments across tidal inundation gradients. To unravel the role of tide-related regimes on the structure and functionality of root associated bacteria, the rhizospheric soil of Salicornia strobilacea (synonym of Halocnemum strobilaceum) plants was studied in a tidal zone of the coastline of Southern Tunisia. Although total counts of cultivable bacteria did not change in the rhizosphere of plants grown along a tidal gradient, significant differences were observed in the diversity of both the cultivable and uncultivable bacterial communities. This observation indicates that the tidal regime is contributing to the bacterial species selection in the rhizosphere. Despite the observed diversity in the bacterial community structure, the plant growth promoting (PGP) potential of cultivable rhizospheric bacteria, assessed through in vitro and in vivo tests, was equally distributed along the tidal gradient. Root colonization tests with selected strains proved that halophyte rhizospheric bacteria (i) stably colonize S. strobilacea rhizoplane and the plant shoot suggesting that they move from the root to the shoot and (ii) are capable of improving plant growth. The versatility in the root colonization, the overall PGP traits and the in vivo plant growth promotion under saline condition suggest that such beneficial activities likely take place naturally under a range of tidal regimes. PMID:27597846

  11. Salicornia strobilacea (Synonym of Halocnemum strobilaceum) Grown under Different Tidal Regimes Selects Rhizosphere Bacteria Capable of Promoting Plant Growth.

    PubMed

    Marasco, Ramona; Mapelli, Francesca; Rolli, Eleonora; Mosqueira, Maria J; Fusi, Marco; Bariselli, Paola; Reddy, Muppala; Cherif, Ameur; Tsiamis, George; Borin, Sara; Daffonchio, Daniele

    2016-01-01

    Halophytes classified under the common name of salicornia colonize salty and coastal environments across tidal inundation gradients. To unravel the role of tide-related regimes on the structure and functionality of root associated bacteria, the rhizospheric soil of Salicornia strobilacea (synonym of Halocnemum strobilaceum) plants was studied in a tidal zone of the coastline of Southern Tunisia. Although total counts of cultivable bacteria did not change in the rhizosphere of plants grown along a tidal gradient, significant differences were observed in the diversity of both the cultivable and uncultivable bacterial communities. This observation indicates that the tidal regime is contributing to the bacterial species selection in the rhizosphere. Despite the observed diversity in the bacterial community structure, the plant growth promoting (PGP) potential of cultivable rhizospheric bacteria, assessed through in vitro and in vivo tests, was equally distributed along the tidal gradient. Root colonization tests with selected strains proved that halophyte rhizospheric bacteria (i) stably colonize S. strobilacea rhizoplane and the plant shoot suggesting that they move from the root to the shoot and (ii) are capable of improving plant growth. The versatility in the root colonization, the overall PGP traits and the in vivo plant growth promotion under saline condition suggest that such beneficial activities likely take place naturally under a range of tidal regimes. PMID:27597846

  12. Genomic selection in plant breeding: knowledge and prospects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    “Genomic selection,” the ability to select for even complex, quantitative traits based on marker data alone, has arisen from the conjunction of new high throughput marker technologies and new statistical methods needed to analyze the data. This review surveys what is known about these technologies, ...

  13. Directional versus Stabilizing Selection for Developmental Time in Natural and Laboratory Populations of Flour Beetles.

    PubMed

    Dawson, P S

    1975-08-01

    Artificial selection for fast development is successful in long-established laboratory populations of Tribolium, but not in strains recently derived from natural populations. It is shown that selection against fast development in dense, synchronized cultures operates through cannibalism of early pupae by larvae. Since standard husbandry procedures for laboratory strains involve the periodic creation of dense, synchronized cultures, it is suggested that these populations are subjected to stabilizing selection for intermediate developmental time. Natural populations, on the other hand, are probably subjected to directional selection for rapid development. PMID:17248688

  14. Natural selection favors rapid reproductive phenology in Potentilla pulcherrima (Rosaceae) at opposite ends of a subalpine snowmelt gradient.

    PubMed

    Stinson, Kristina A

    2004-04-01

    In high altitude plants, flowering quickly ensures reproductive success within a short snow-free period, but limits maturation time and fecundity. Natural selection on prefloration intervals may therefore vary in contrasting snowmelt environments and could influence the outcome of phenological responses to climatic change. This study investigated adaptive differentiation and plasticity of prefloration intervals in the subalpine perennial Potentilla pulcherrima. Three years of in situ field observations were combined with phenotypic selection analyses and a common garden experiment. Plants from high, intermediate, and low altitudes expressed similar prefloration intervals and plasticity when grown at common altitude, indicating no evidence for adaptive differentiation. Selection on the prefloration interval was negative at both low and high altitudes before and after accounting for strong positive selection on size. Environmental differences between high and low altitudes indicated that long, dry seasons and short, wet seasons both favored rapid reproduction. Therefore, quicker reproduction was adaptive in response to late snowmelt, but slower reproduction in response to earlier snowmelt appeared to be maladaptive. Selection differed marginally between late snowmelt years and dry ones. Plastic responses to future precipitation patterns may therefore have positive or negative effects on fitness within a single species, depending upon altitude and year. PMID:21653408

  15. Concentration-mortality responses of Myzus persicae and natural enemies to selected insecticides.

    PubMed

    Bacci, Leandro; Rosado, Jander F; Picanço, Marcelo C; Pereira, Eliseu J G; Silva, Gerson A; Martins, Júlio C

    2012-01-01

    The toxicity of six insecticides was determined for the peach-potato aphid, Myzus persicae (Hemiptera: Aphididae), and some of its natural enemies - the predatory beetles Cycloneda sanguinea (Coccinellidae) and Acanthinus sp. (Anthicidae), and the wasp parasitoid Diaeretiella rapae (Aphidiidae). Natural enemies from these groups are important natural biological control agents in a number of agroecosystems, and insecticides potentially safe to these non-target organisms should be identified using standardized tests. Thus, concentration-mortality bioassays were carried out with both the aphid and its natural enemies to assess the toxicity and selectivity of acephate, deltamethrin, dimethoate, methamidophos, methyl parathion, and pirimicarb. The latter insecticide was highly selective to all natural enemies tested, and its LC(90) for M. persicae was 14-fold lower than the field rate recommended for control of the aphid in brassica crops. Methyl parathion also showed selectivity to C. sanguinea and Acanthinus sp., but not to D. rapae. Acephate was the least potent insecticide against M. persicae and was equally or more toxic to the natural enemies relative to the aphid. Pirimicarb and methyl parathion were efficient against M. persicae and selective in favor of two of the natural enemies tested. Acanthinus sp. and C. sanguinea were more tolerant to the insecticides than was the parasitoid D. rapae. This study shows that there are selective insecticides that may be compatible with conservation of natural enemies in brassica crops, which is important practical information to improve integrated pest management systems in these crops. PMID:22755540

  16. Nematodes Associated with Plants from Naturally Acidic Wetlands Soil

    PubMed Central

    Cox, Robert John; Smart, Grover C.

    1994-01-01

    Four plants, Cyperus ochraceus, Eriocaulon compressum, Lythrum alatum, and Xyris jupicai, growing along the shoreline of an oligotrophic lake in north central Florida were sampled for nematodes. The nematodes recovered were placed in four trophic groups: bacterivores, herbivores, omnivores, and predators. When the nematodes on all plants were considered, 27% were bacterivores, 23% were herbivores, 7% were omnivores, and 43% were predators. Tripyla was the dominant predator and the dominant genus of all nematodes, and Malenchus was the dominant herbivore. Dominance was not clearly pronounced in the other trophic groups. PMID:19279927

  17. The Discovery and Nature of Evolution by Natural Selection: Misconceptions and Lessons from the History of Science.

    ERIC Educational Resources Information Center

    McComas, William F.

    1997-01-01

    Explains the misconceptions found in the traditional textbook presentation of the theory and the history of the theory of evolution. Outlines a more accurate and complete telling of the history of the discovery of evolution by natural selection. Contains 50 references. (DDR)

  18. NEXT GENERATION NUCLEAR PLANT LICENSING BASIS EVENT SELECTION WHITE PAPER

    SciTech Connect

    Mark Holbrook

    2010-09-01

    The Next Generation Nuclear Plant (NGNP) will be a licensed commercial high temperature gas-cooled reactor (HTGR) plant capable of producing the electricity and high temperature process heat for industrial markets supporting a range of end-user applications. The NGNP Project has adopted the 10 CFR 52 Combined License (COL) application process, as recommended in the Report to Congress, dated August 2008, as the foundation for the NGNP licensing strategy. NRC licensing of the NGNP plant utilizing this process will demonstrate the efficacy of licensing future HTGRs for commercial industrial applications. This white paper is one in a series of submittals that will address key generic issues of the COL priority licensing topics as part of the process for establishing HTGR regulatory requirements.

  19. Potential of hypocotyl diameter in family selection aiming at plant architecture improvement of common bean.

    PubMed

    Oliveira, A M C; Batista, R O; Carneiro, P C S; Carneiro, J E S; Cruz, C D

    2015-01-01

    Cultivars of common bean with more erect plant architecture and greater tolerance to degree of lodging are required by producers. Thus, to evaluate the potential of hypocotyl diameter (HD) in family selection for plant architecture improvement of common bean, the HDs of 32 F2 plants were measured in 3 distinct populations, and the characteristics related to plant architecture were analyzed in their progenies. Ninety-six F2:3 families and 4 controls were evaluated in a randomized block design, with 3 replications, analyzing plant architecture grade, HD, and grain yield during the winter 2010 and drought 2011 seasons. We found that the correlation between the HD of F2 plants and traits related to plant architecture of F2:3 progenies were of low magnitude compared to the estimates for correlations considering the parents, indicating a high environmental influence on HD in bean plants. There was a predominance of additive genetic effects on the determination of hypocotyl diameter, which showed higher precision and accuracy compared to plant architecture grade. Thus, this characteristic can be used to select progenies in plant architecture improvement of common beans; however, selection must be based on the means of at least 39 plants in the plot, according to the results of repeatability analysis. PMID:26436392

  20. Is natural background or radiation from nuclear power plants leukemogenic

    SciTech Connect

    Cronkite, E.P.

    1989-01-01

    The objective in this review is to provide some facts about normal hemopoietic cell proliferation relevant to leukemogenesis, physical, chemical, and biological facts about radiation effects with the hope that each person will be able to decide for themselves whether background radiation or emissions from nuclear power plants and facilities significantly add to the spontaneous leukemia incidence. 23 refs., 1 tab.

  1. [Foraging habitat selection of Siberian Crane (Grus leucogeranus) during autumn migration period in the Momoge Nature Reserve].

    PubMed

    Kong, Wei-Yao; Zheng, Zhen-He; Wu, Jin-Cai; Ning, Yu; Wang, Yong; Han, Xiao-Dong

    2013-06-01

    In autumn of 2008 and 2009, we studied the foraging habitat selection of Siberian Crane (Grus leucogeranus) in the Momoge Nature Reserve of Jilin province. Using the resource selection index, resource selection functions, and the chi-squared test, we found that the Siberian Crane exhibited selectivity in their preferred foraging environments in relation to the distance to human disturbances, vegetation density, coverage and height, foraging vegetation density and water level. Interestingly, this selectivity in regards to large scale disturbances was lower than other factors. The characteristics of favorite foraging habits of Siberian Cranes include a variety of factors: a distance >5 000 m from a national highway, >1 500 m from a non-gravel road, >1 000 m from the nearest road, >1 000 m from a residential area, >1 000 m from farmland; plant density between 20 and 50 grass/m(2); plant coverage lower than 10%; plant height lower than 20 cm; Scirpus planiclmis density between 1 and 50 grass/m(2); Scirpus triqueter density between 1 and 10 grass/m(2); and the water level between 40 and 60 cm. The resource selection functions of Siberian Crane foraging habitat in autumn can be described thusly: Logistic (P) = 0.663 + 0.565×distance to national highway + 0.042×distance to non-gravel road + 0.519×distance to the nearest road + 0.353×distance to residential area + 0.169×distance to farmland - 0.455×vegetation density - 0.618×vegetation coverage - 0.548×vegetation height - 0.158×Scirpus planiclmis density - 0.404×Scirpus triqueter density + 0.920×water level,T (x) =e(Logistic(p)) / [1 + e(Logistic(p))], with an overall prediction accuracy of 82.9%. PMID:23775991

  2. Site-specific conditions influence plant naturalization: The case of alien Proteaceae in South Africa

    NASA Astrophysics Data System (ADS)

    Moodley, Desika; Geerts, Sjirk; Rebelo, Tony; Richardson, David M.; Wilson, John R. U.

    2014-08-01

    The outcome of plant introductions is often considered in binary terms (invasive or non-invasive). However, most species experience a time lag before naturalization occurs, and many species become naturalized at some sites but not at others. It is therefore important to understand the site-specific mechanisms underlying naturalization. Proteaceae is an interesting case as some species are widespread invaders, while others, despite a long history of cultivation, show no signs of naturalization. At least 26 non-native Proteaceae species have been introduced to, and are cultivated in, South Africa. We mapped populations and examined differences between naturalized and non-naturalized populations (e.g. propagule pressure, land use and bioclimatic suitability). Of the 15 species surveyed, 6 were naturalized at one or more sites. Of these, Hakea salicifolia is most widely cultivated, but is only naturalizing in some areas (32 naturalized populations out of 62 populations that were surveyed). We found propagule pressure to be the most important determinant of naturalization for H. salicifolia. However, in suboptimal climatic conditions, naturalization only occurred if micro-site conditions were suitable, i.e. there was some disturbance and water available. For the other naturalized species there were few sites to compare, but we came to similar conclusions - Banksia integrifolia only naturalized at the site where it was planted the longest; Banksia serrata only naturalized at a site influenced by fire regimes; while Banksia formosa naturalized at sites with high propagule pressure, absence of fires and where there is no active clearing of the plants. Naturalization of Proteaceae in South Africa appears to be strongly mediated by site-specific anthropogenic activities (e.g. many planted individuals and water availability). More broadly, we argue that invasion biology needs to focus more closely on the mechanisms by which species and pathways interact to determine the

  3. Experience-dependent specialization of receptive field surround for selective coding of natural scenes.

    PubMed

    Pecka, Michael; Han, Yunyun; Sader, Elie; Mrsic-Flogel, Thomas D

    2014-10-22

    At eye opening, neurons in primary visual cortex (V1) are selective for stimulus features, but circuits continue to refine in an experience-dependent manner for some weeks thereafter. How these changes contribute to the coding of visual features embedded in complex natural scenes remains unknown. Here we show that normal visual experience after eye opening is required for V1 neurons to develop a sensitivity for the statistical structure of natural stimuli extending beyond the boundaries of their receptive fields (RFs), which leads to improvements in coding efficiency for full-field natural scenes (increased selectivity and information rate). These improvements are mediated by an experience-dependent increase in the effectiveness of natural surround stimuli to hyperpolarize the membrane potential specifically during RF-stimulus epochs triggering action potentials. We suggest that neural circuits underlying surround modulation are shaped by the statistical structure of visual input, which leads to more selective coding of features in natural scenes. PMID:25263755

  4. Four decades of opposing natural and human-induced artificial selection acting on Windermere pike (Esox lucius).

    PubMed

    Carlson, Stephanie M; Edeline, Eric; Asbjørn Vøllestad, L; Haugen, Thrond O; Winfield, Ian J; Fletcher, Janice M; Ben James, J; Stenseth, Nils Chr

    2007-06-01

    The ability of natural selection to drive local adaptation has been appreciated ever since Darwin. Whether human impacts can impede the adaptive process has received less attention. We tested this hypothesis by quantifying natural selection and harvest selection acting on a freshwater fish (pike) over four decades. Across the time series, directional natural selection tended to favour large individuals whereas the fishery targeted large individuals. Moreover, non-linear natural selection tended to favour intermediate sized fish whereas the fishery targeted intermediate sized fish because the smallest and largest individuals were often not captured. Thus, our results unequivocally demonstrate that natural selection and fishery selection often acted in opposite directions within this natural system. Moreover, the two selective factors combined to produce reduced fitness overall and stronger stabilizing selection relative to natural selection acting alone. The long-term ramifications of such human-induced modifications to adaptive landscapes are currently unknown and certainly warrant further investigation. PMID:17498150

  5. Natural Selection Constrains Neutral Diversity across A Wide Range of Species

    PubMed Central

    Corbett-Detig, Russell B.; Hartl, Daniel L.; Sackton, Timothy B.

    2015-01-01

    The neutral theory of molecular evolution predicts that the amount of neutral polymorphisms within a species will increase proportionally with the census population size (Nc). However, this prediction has not been borne out in practice: while the range of Nc spans many orders of magnitude, levels of genetic diversity within species fall in a comparatively narrow range. Although theoretical arguments have invoked the increased efficacy of natural selection in larger populations to explain this discrepancy, few direct empirical tests of this hypothesis have been conducted. In this work, we provide a direct test of this hypothesis using population genomic data from a wide range of taxonomically diverse species. To do this, we relied on the fact that the impact of natural selection on linked neutral diversity depends on the local recombinational environment. In regions of relatively low recombination, selected variants affect more neutral sites through linkage, and the resulting correlation between recombination and polymorphism allows a quantitative assessment of the magnitude of the impact of selection on linked neutral diversity. By comparing whole genome polymorphism data and genetic maps using a coalescent modeling framework, we estimate the degree to which natural selection reduces linked neutral diversity for 40 species of obligately sexual eukaryotes. We then show that the magnitude of the impact of natural selection is positively correlated with Nc, based on body size and species range as proxies for census population size. These results demonstrate that natural selection removes more variation at linked neutral sites in species with large Nc than those with small Nc and provides direct empirical evidence that natural selection constrains levels of neutral genetic diversity across many species. This implies that natural selection may provide an explanation for this longstanding paradox of population genetics. PMID:25859758

  6. Cytokinin production by plant growth promoting rhizobacteria and selected mutants.

    PubMed

    García de Salamone, I E; Hynes, R K; Nelson, L M

    2001-05-01

    One of the proposed mechanisms by which rhizobacteria enhance plant growth is through the production of plant growth regulators. Five plant growth promoting rhizobacterial (PGPR) strains produced the cytokinin dihydrozeatin riboside (DHZR) in pure culture. Cytokinin production by Pseudomonas fluorescens G20-18, a rifampicin-resistant mutant (RIF), and two TnphoA-derived mutants (CNT1, CNT2), with reduced capacity to synthesize cytokinins, was further characterized in pure culture using immunoassay and thin layer chromatography. G20-18 produced higher amounts of three cytokinins, isopentenyl adenosine (IPA), trans-zeatin ribose (ZR), and DHZR than the three mutants during stationary phase. IPA was the major metabolite produced, but the proportion of ZR and DHZR accumulated by CNT1 and CNT2 increased with time. No differences were observed between strain G20-18 and the mutants in the amounts of indole acetic acid synthesized, nor were gibberellins detected in supernatants of any of the strains. Addition of 10(-5) M adenine increased cytokinin production in 96- and 168-h cultures of strain G20-18 by approximately 67%. G20-18 and the mutants CNT1 and CNT2 may be useful for determination of the role of cytokinin production in plant growth promotion by PGPR. PMID:11400730

  7. Stimulated rhizodegradation of atrazaine by selected plant species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of vegetative buffer strips (VBS) in removing herbicides deposited from surface runoff is related to the ability of plant species to promote rapid herbicide degradation. A growth chamber study was conducted to investigate the rhizodegradation of 14C-atrazine and the relationship of degr...

  8. THEORETICAL INVESTIGATION OF SELECTED TRACE ELEMENTS IN COAL GASIFICATION PLANTS

    EPA Science Inventory

    The report gives results of a theoretical investigation of the disposition of five volatile trace elements (arsenic, boron, lead, selenium, and mercury) in SNG-producing coal gasification plants. Three coal gasification processes (dry-bottom Lurgi, Koppers-Totzek, and HYGAS) were...

  9. Materials selection for the SRC-I demonstration plant

    SciTech Connect

    Baumert, K.L.; Barnett, W.P.

    1983-10-01

    Three major areas of concern with respect to materials are: rapid wear of letdown valves; erosion in hot slurry lines; and solvent fractionation column corrosion. Except for the transfer of hot slurry in the presence of H/SUB/2S and hydrogen, technology developed in petroleum refineries and in cryogenic industries will be used in the plant.

  10. Diuretic effects of selected Thai indigenous medicinal plants in rats.

    PubMed

    Sripanidkulchai, B; Wongpanich, V; Laupattarakasem, P; Suwansaksri, J; Jirakulsomchok, D

    2001-05-01

    Extracts of five indigenous Thai medicinal having ethnomedical application in the treatment of dysuria were investigated for their diuretic activity. Root extracts of Ananas comosus and Carica papaya, given orally to rats at a dose of 10 mg/kg, demonstrated significantly increased urine output (P < 0.01) which was 79 and 74%, respectively, of the effect of an equivalent dose of hydrochlorothiazide. Both plant extracts gave similar profiles of urinary electrolyte excretion to that of the hydrochlorothiazide. The analyses of the urinary osmolality and electrolyte excretion per unit time suggest the observed effect of A. comosus was intrinsic, whereas that of C. papaya may have resulted from a high salt content of this extract. However, our experimental evidence on the diuretic activities of the other three plants did not parallel their local utilization for dysuria. It was found that the rhizome of Imperata cylindrica apparently inhibited the urination of rats whereas the rhizome of Cyperus rotundus and the stem of Averrhoa carambola failed to demonstrate any diuretic activities. These results indicate that two of the plants investigated exert their action by causing diuresis. The other three plants need further investigation to determine their effectiveness in the treatment of dysuria. PMID:11297849

  11. Stimulated Rhizodegradation of Atrazine by Selected Plant Species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of vegetative buffer strips (VBS) in removing herbicides from surface runoff is related to the ability of plant species to promote rapid herbicide degradation. A growth chamber study was conducted to investigate the rhizodegradation of 14C-atrazine and the relationship of degradation w...

  12. Plant selection and soil legacy enhance long-term biodiversity effects.

    PubMed

    Zuppinger-Dingley, Debra; Flynn, Dan F B; De Deyn, Gerlinde B; Petermann, Jana S; Schmid, Bernhard

    2016-04-01

    Plant-plant and plant-soil interactions can help maintain plant diversity and ecosystem functions. Changes in these interactions may underlie experimentally observed increases in biodiversity effects over time via the selection of genotypes adapted to low or high plant diversity. Little is known, however, about such community-history effects and particularly the role of plant-soil interactions in this process. Soil-legacy effects may occur if co-evolved interactions with soil communities either positively or negatively modify plant biodiversity effects. We tested how plant selection and soil legacy influence biodiversity effects on productivity, and whether such effects increase the resistance of the communities to invasion by weeds. We used two plant selection treatments: parental plants growing in monoculture or in mixture over 8 yr in a grassland biodiversity experiment in the field, which we term monoculture types and mixture types. The two soil-legacy treatments used in this study were neutral soil inoculated with live or sterilized soil inocula collected from the same plots in the biodiversity experiment. For each of the four factorial combinations, seedlings of eight species were grown in monocultures or four-species mixtures in pots in an experimental garden over 15 weeks. Soil legacy (live inoculum) strongly increased biodiversity complementarity effects for communities of mixture types, and to a significantly weaker extent for communities of monoculture types. This may be attributed to negative plant-soil feedbacks suffered by mixture types in monocultures, whereas monoculture types had positive plant-soil feedbacks, in both monocultures and mixtures. Monocultures of mixture types were most strongly invaded by weeds, presumably due to increased pathogen susceptibility, reduced biomass, and altered plant-soil interactions of mixture types. These results show that biodiversity effects in experimental grassland communities can be modified by the evolution of

  13. Plant protein and secondary metabolites influence diet selection in a mammalian specialist herbivore

    PubMed Central

    Ulappa, Amy C.; Kelsey, Rick G.; Frye, Graham G.; Rachlow, Janet L.; Shipley, Lisa A.; Bond, Laura; Pu, Xinzhu; Forbey, Jennifer Sorensen

    2015-01-01

    For herbivores, nutrient intake is limited by the relatively low nutritional quality of plants and high concentrations of potentially toxic defensive compounds (plant secondary metabolites, PSMs) produced by many plants. In response to phytochemical challenges, some herbivores selectively forage on plants with higher nutrient and lower PSM concentrations relative to other plants. Pygmy rabbits (Brachylagus idahoensis) are dietary specialists that feed on sagebrush (Artemisia spp.) and forage on specific plants more than others within a foraging patch. We predicted that the plants with evidence of heavy foraging (browsed plants) would be of higher dietary quality than plants that were not browsed (unbrowsed). We used model selection to determine which phytochemical variables best explained the difference between browsed and unbrowsed plants. Higher crude protein increased the odds that plants would be browsed by pygmy rabbits and the opposite was the case for certain PSMs. Additionally, because pygmy rabbits can occupy foraging patches (burrows) for consecutive years, their browsing may influence the nutritional and PSM constituents of plants at the burrows. In a post hoc analysis, we did not find a significant relationship between phytochemical concentrations, browse status and burrow occupancy length. We concluded that pygmy rabbits use nutritional and chemical cues while making foraging decisions. PMID:26366011

  14. Measurement of resistant starch by enzymatic digestion in starch and selected plant materials: collaborative study.

    PubMed

    McCleary, Barry V; McNally, Marian; Rossiter, Patricia

    2002-01-01

    Interlaboratory performance statistics was determined for a method developed to measure the resistant starch (RS) content of selected plant food products and a range of commercial starch samples. Food materials examined contained RS (cooked kidney beans, green banana, and corn flakes) and commercial starches, most of which naturally contain, or were processed to yield, elevated RS levels. The method evaluated was optimized to yield RS values in agreement with those reported for in vivo studies. Thirty-seven laboratories tested 8 pairs of blind duplicate starch or plant material samples with RS values between 0.6 (regular maize starch) and 64% (fresh weight basis). For matrixes excluding regular maize starch, repeatability relative standard deviation (RSDr) values ranged from 1.97 to 4.2%, and reproducibility relative standard deviation (RSDR) values ranged from 4.58 to 10.9%. The range of applicability of the test is 2-64% RS. The method is not suitable for products with <1% RS (e.g., regular maize starch; 0.6% RS). For such products, RSDr and RSDR values are unacceptably high. PMID:12374410

  15. Distinct invasion strategies operating within a natural annual plant system.

    PubMed

    Lai, Hao Ran; Mayfield, Margaret M; Gay-des-Combes, Justine M; Spiegelberger, Thomas; Dwyer, John M

    2015-04-01

    Alien plant species are known to have a wide range of impacts on recipient communities, from resident species' exclusions to coexistence with resident species. It remains unclear; however, if this variety of impacts is due to different invader strategies, features of recipient communities or both. To test this, we examined multiple plant invasions of a single ecosystem in southwestern Australia. We used extensive community data to calculate pairwise segregation between target alien species and many co-occurring species. We related segregation to species' positions along community trait hierarchies and identified at least two distinct invasion strategies: 'exploiters' which occupy high positions along key trait hierarchies and reduce local native species diversity (particularly in nutrient-enriched situations), and 'coexisters' who occupy intermediate trait positions and have no discernable impact on native diversity. We conclude that trait hierarchies, linked to measures of competition, can provide valuable insights about the processes driving different invasion outcomes. PMID:25728390

  16. Rational selection of structurally diverse natural product scaffolds with favorable ADME properties for drug discovery.

    PubMed

    Samiulla, D S; Vaidyanathan, V V; Arun, P C; Balan, G; Blaze, M; Bondre, S; Chandrasekhar, G; Gadakh, A; Kumar, R; Kharvi, G; Kim, H O; Kumar, S; Malikayil, J A; Moger, M; Mone, M K; Nagarjuna, P; Ogbu, C; Pendhalkar, D; Rao, A V S Raja; Rao, G Venkateshwar; Sarma, V K; Shaik, S; Sharma, G V R; Singh, S; Sreedhar, C; Sonawane, R; Timmanna, U; Hardy, L W

    2005-01-01

    Natural product analogs are significant sources for therapeutic agents. To capitalize efficiently on the effective features of naturally occurring substances, a natural product-based library production platform has been devised at Aurigene for drug lead discovery. This approach combines the attractive biological and physicochemical properties of natural product scaffolds, provided by eons of natural selection, with the chemical diversity available from parallel synthetic methods. Virtual property analysis, using computational methods described here, guides the selection of a set of natural product scaffolds that are both structurally diverse and likely to have favorable pharmacokinetic properties. The experimental characterization of several in vitro ADME properties of twenty of these scaffolds, and of a small set of designed congeners based upon one scaffold, is also described. These data confirm that most of the scaffolds and the designed library members have properties favorable to their utilization for creating libraries of lead-like molecules. PMID:15789560

  17. From Ends to Causes (and Back Again) by Metaphor: The Paradox of Natural Selection

    ERIC Educational Resources Information Center

    Blancke, Stefaan; Schellens, Tammy; Soetaert, Ronald; Van Keer, Hilde; Braeckman, Johan

    2014-01-01

    Natural selection is one of the most famous metaphors in the history of science. Charles Darwin used the metaphor and the underlying analogy to frame his ideas about evolution and its main driving mechanism into a full-fledged theory. Because the metaphor turned out to be such a powerful epistemic tool, Darwin naturally assumed that he could also…

  18. The nature of spectral signatures in native arid plant communities

    NASA Technical Reports Server (NTRS)

    Conn, J. S.; Foster, K. E.; Mcginnies, W. G.

    1976-01-01

    Radiometric data in ERTS bands 5 and 7 of spectral signature components were compared to the overall signatures obtained from an airborne radiometric data collection system flown at low altitude. Results indicate that due to the low density and low vigor of the vegetation, vegetation has little effect on the overall signature, thus making differentiation of desert plant communities on the basis of spectral signature extremely difficult.

  19. The Nature of Selection and Judging for the Teacher of the Year Award.

    ERIC Educational Resources Information Center

    McKenna, Bonnie; And Others

    This paper reports on the investigation of the operation of the Teacher of the Year Award program in 28 states. It focuses on the method of selection for recipients of this award, and explores the nature of the judging process used in selecting candidates at both the state and national levels. Specific objectives are: (1) to determine the criteria…

  20. Thoughts Toward a Theory of Natural Selection: The Importance of Microbial Experimental Evolution.

    PubMed

    Dykhuizen, Daniel

    2016-03-01

    Natural selection should no longer be thought of simply as a primitive (magical) concept that can be used to support all kinds of evolutionary theorizing. We need to develop causal theories of natural selection; how it arises. Because the factors contributing to the creation of natural selection are expected to be complex and intertwined, theories explaining the causes of natural selection can only be developed through the experimental method. Microbial experimental evolution provides many benefits that using other organisms does not. Microorganisms are small, so millions can be housed in a test tube; they have short generation times, so evolution over hundreds of generations can be easily studied; they can grow in chemically defined media, so the environment can be precisely defined; and they can be frozen, so the fitness of strains or populations can be directly compared across time. Microbial evolution experiments can be divided into two types. The first is to measure the selection coefficient of two known strains over the first 50 or so generations, before advantageous mutations rise to high frequency. This type of experiment can be used to directly test hypotheses. The second is to allow microbial cultures to evolve over many hundreds or thousands of generations and follow the genetic changes, to infer what phenotypes are selected. In the last section of this article, I propose that selection coefficients are not constant, but change as the population becomes fitter, introducing the idea of the selection space. PMID:26747663

  1. Understanding the nature of nuclear power plant risk

    SciTech Connect

    Denning, R. S.

    2012-07-01

    This paper describes the evolution of understanding of severe accident consequences from the non-mechanistic assumptions of WASH-740 to WASH-1400, NUREG-1150, SOARCA and today in the interpretation of the consequences of the accident at Fukushima. As opposed to the general perception, the radiological human health consequences to members of the Japanese public from the Fukushima accident will be small despite meltdowns at three reactors and loss of containment integrity. In contrast, the radiation-related societal impacts present a substantial additional economic burden on top of the monumental task of economic recovery from the nonnuclear aspects of the earthquake and tsunami damage. The Fukushima accident provides additional evidence that we have mis-characterized the risk of nuclear power plant accidents to ourselves and to the public. The human health risks are extremely small even to people living next door to a nuclear power plant. The principal risk associated with a nuclear power plant accident involves societal impacts: relocation of people, loss of land use, loss of contaminated products, decontamination costs and the need for replacement power. Although two of the three probabilistic safety goals of the NRC address societal risk, the associated quantitative health objectives in reality only address individual human health risk. This paper describes the types of analysis that would address compliance with the societal goals. (authors)

  2. Response to selection under controlled environment versus natural selection in diverse regions across Canada

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Red clover is a widely adaptable and productive forage legume species found in most temperate regions of the world. To date, specific selection techniques for identifying genotypes with superior persistence have not been successful in improving the general adaptation and the long-term persistence o...

  3. A simple and rapid method for calixarene-based selective extraction of bioactive molecules from natural products.

    PubMed

    Segneanu, Adina-Elena; Damian, Daniel; Hulka, Iosif; Grozescu, Ioan; Salifoglou, Athanasios

    2016-03-01

    Natural products derived from medicinal plants have gained an important role in drug discovery due to their complex and abundant composition of secondary metabolites, with their structurally unique molecular components bearing a significant number of stereo-centers exhibiting high specificity linked to biological activity. Usually, the extraction process of natural products involves various techniques targeting separation of a specific class of compounds from a highly complex matrix. Aiding the process entails the use of well-defined and selective molecular extractants with distinctly configured structural attributes. Calixarenes conceivably belong to that class of molecules. They have been studied intensely over the years in an effort to develop new and highly selective receptors for biomolecules. These macrocycles, which display remarkable structural architectures and properties, could help usher a new approach in the efficient separation of specific classes of compounds from complex matrices in natural products. A simple and rapid such extraction method is presented herein, based on host-guest interaction(s) between a calixarene synthetic receptor, 4-tert-butyl-calix[6]arene, and natural biomolecular targets (amino acids and peptides) from Helleborus purpurascens and Viscum album. Advanced physicochemical methods (including GC-MS and chip-based nanoESI-MS analysis) suggest that the molecular structure and specifically the calixarene cavity size are closely linked to the nature of compounds separated. Incorporation of biomolecules and modification of the macrocyclic architecture during separation were probed and confirmed by scanning electronic microscopy and atomic force microscopy. The collective results project calixarene as a promising molecular extractant candidate, facilitating the selective separation of amino acids and peptides from natural products. PMID:26597796

  4. Selective Effect of Pesticides on Plant--A Review.

    PubMed

    Parween, Talat; Jan, Sumira; Mahmooduzzafar, Sumira; Fatma, Tasneem; Siddiqui, Zahid Hameed

    2016-01-01

    This review represents systematic and integrated picture of pesticide exposure to plant and its effect on growth and metabolism. Decades ago, agrochemicals were introduced aiming at enhancing crop yields and protecting crops from pests. Due to adaptation and resistance developed by pests to chemicals, every year higher amounts and new chemical compounds are used to protect crops, causing undesired side effects and raising the costs of food production. Biological chemical free agriculture is gaining also more and more support but it is still not able to respond to the need for producing massive amounts of food. The use of agrochemicals, including pesticides, remains a common practice especially in tropical regions and South countries. Cheap compounds, such as DDT, HCH, and Lindane, that are environmentally persistent, are today banned from agriculture use in developed countries, but remain popular in developing countries. As a consequence, persistent residues of these chemicals contaminate food and disperse in the environment. Therefore, the thrust of this paper was to review the application of pesticides effect early from germination to growth of the plant, leading to alteration in biochemical, physiological and different enzymatic and non-enzymatic antioxidants which ultimately affect the yield and resulted in residues in plant, vegetables, and fruits. PMID:25216296

  5. Light dependency of VOC emissions from selected Mediterranean plant species

    NASA Astrophysics Data System (ADS)

    Owen, S. M.; Harley, P.; Guenther, A.; Hewitt, C. N.

    The light, temperature and stomatal conductance dependencies of volatile organic compound (VOC) emissions from ten plant species commonly found in the Mediterranean region were studied using a fully controlled leaf cuvette in the laboratory. At standard conditions of temperature and light (30°C and 1000 μmol m -2 s -1 PAR), low emitting species ( Arbutus unedo, Pinus halepensis, Cistus incanus, Cistus salvifolius, Rosmarinus officinalis and Thymus vulgaris) emitted between 0.1 and 5.0 μg (C) (total VOCs) g -1 dw h -1, a medium emitter ( Pinus pinea) emitted between 5 and 10 μg (C) g -1 dw h -1 and high emitters ( Cistus monspeliensis, Lavendula stoechas and Quercus sp.) emitted more than 10 μg (C) g -1 dw h -1. VOC emissions from all of the plant species investigated showed some degree of light dependency, which was distinguishable from temperature dependency. Emissions of all compounds from Quercus sp. were light dependent. Ocimene was one of several monoterpene compounds emitted by P. pinea and was strongly correlated to light. Only a fraction of monoterpene emissions from C. incanus exhibited apparent weak light dependency but emissions from this plant species were strongly correlated to temperature. Data presented here are consistent with past studies, which show that emissions are independent of stomatal conductance. These results may allow more accurate predictions of monoterpene emission fluxes from the Mediterranean region to be made.

  6. Ball mill assisted rapid mechanochemical extraction method for natural products from plants.

    PubMed

    Wang, Man; Bi, Wentao; Huang, Xiaohua; Chen, David Da Yong

    2016-06-01

    A ball mill assisted mechanochemical extraction method was developed to extract compounds of natural product (NP) from plant using ionic liquid (IL). A small volume ball mill, also known as PastPrep(®) Homogenizer, which is often used for high-speed lysis of biological samples and for other applications, was used to dramatically increase the speed, completeness and reproducibility of the extraction process at room temperature to preserve the chemical integrity of the extracted compounds. In this study, tanshinones were selected as target compounds to evaluate the performance of this extraction method. Factors affecting the extraction efficiency, such as the duration, IL concentration and solid/liquid ratio were systematically optimized using the response surface methodology. Under the optimized conditions, the described method was more efficient and much faster than the conventional extraction methods such as methanol based ultrasound assisted extraction (UAE) and heat reflux extraction (HRE) that consumes a lot more organic solvent. In addition, the natural products of interest were enriched by anion metathesis of ionic liquids, combining extraction and preconcentration in the same process. The extractant was analyzed by HPLC and LC-MS. The reproducibility (RSD, n=5), correlation coefficient (r(2)) of the calibration curve, and the limit of detection, were determined to be in the range of 4.7-5.2%, 0.9992-0.9995, and 20-51ng/mL, respectively. PMID:27157426

  7. Oviposition site selection by Gasterophilus pecorum (Diptera: Gasterophilidae) in its habitat in Kalamaili Nature Reserve, Xinjiang, China

    PubMed Central

    Liu, Shan-Hui; Hu, De-Fu; Li, Kai

    2015-01-01

    Oviposition site selection is an important aspect of the behavioural ecology of insects. A comparison of the habitats used by a species enhances our understanding of their adaptation to altered environments. We collected data on the oviposition behaviours of Gasterophilus pecorum (Diptera: Gasterophilidae) in its habitat in Kalamaili Nature Reserve (KNR), Xinjiang, China between March and October 2014. We found 91 quadrats were used by G. pecorum for oviposition. Examining 13 ecological factors using the t-test, chi-square test, and principal component analysis showed that G. pecorum’s oviposition habitat was preferentially on slopes with inclinations of 10–30° that were semi-sunny, semi-cloudy slopes, in positions high or low on the slopes, with preferences for total plants lower than 10% and Stipa capillata coverage lower than 10% on the low slopes, but Ceratoides latens coverage on the high and intermediate slopes, when the numbers of plant species and families were lower than five. G. pecorum often selected sites at a distance < 2000 m from a water source and average altitude 900–1000 m. The oviposition site selection by G. pecorum may be correlated with the behaviour of Przewalski’s horses (Equus ferus przewalskii), and water and food resources may strongly influence oviposition site selection, as Przewalski’s horses rest and forage in these areas. PMID:26621549

  8. Oviposition site selection by Gasterophilus pecorum (Diptera: Gasterophilidae) in its habitat in Kalamaili Nature Reserve, Xinjiang, China.

    PubMed

    Liu, Shan-Hui; Hu, De-Fu; Li, Kai

    2015-01-01

    Oviposition site selection is an important aspect of the behavioural ecology of insects. A comparison of the habitats used by a species enhances our understanding of their adaptation to altered environments. We collected data on the oviposition behaviours of Gasterophilus pecorum (Diptera: Gasterophilidae) in its habitat in Kalamaili Nature Reserve (KNR), Xinjiang, China between March and October 2014. We found 91 quadrats were used by G. pecorum for oviposition. Examining 13 ecological factors using the t-test, chi-square test, and principal component analysis showed that G. pecorum's oviposition habitat was preferentially on slopes with inclinations of 10-30° that were semi-sunny, semi-cloudy slopes, in positions high or low on the slopes, with preferences for total plants lower than 10% and Stipa capillata coverage lower than 10% on the low slopes, but Ceratoides latens coverage on the high and intermediate slopes, when the numbers of plant species and families were lower than five. G. pecorum often selected sites at a distance < 2000 m from a water source and average altitude 900-1000 m. The oviposition site selection by G. pecorum may be correlated with the behaviour of Przewalski's horses (Equus ferus przewalskii), and water and food resources may strongly influence oviposition site selection, as Przewalski's horses rest and forage in these areas. PMID:26621549

  9. Method and apparatus for selectively harvesting multiple components of a plant material

    DOEpatents

    Hoskinson, Reed L.; Hess, Richard J.; Kenney, Kevin L.; Svoboda, John M.; Foust, Thomas D.

    2004-05-04

    A method and apparatus for selectively harvesting multiple components of a plant material. A grain component is separated from the plant material such as by processing the plant material through a primary threshing and separating mechanism. At least one additional component of the plant material is selectively harvested such as by subjecting the plant material to a secondary threshing and separating mechanism. For example, the stems of a plant material may be broken at a location adjacent one or more nodes thereof with the nodes and the internodal stem portions being subsequently separated for harvesting. The at least one additional component (e.g., the internodal stems) may then be consolidated and packaged for subsequent use or processing. The harvesting of the grain and of the at least one additional component may occur within a single harvesting machine, for example, during a single pass over a crop field.

  10. Selective Pressure along a Latitudinal Gradient Affects Subindividual Variation in Plants

    PubMed Central

    Sobral, Mar; Guitián, José; Guitián, Pablo; Larrinaga, Asier R.

    2013-01-01

    Individual plants produce repeated structures such as leaves, flowers or fruits, which, although belonging to the same genotype, are not phenotypically identical. Such subindividual variation reflects the potential of individual genotypes to vary with micro-environmental conditions. Furthermore, variation in organ traits imposes costs to foraging animals such as time, energy and increased predation risk. Therefore, animals that interact with plants may respond to this variation and affect plant fitness. Thus, phenotypic variation within an individual plant could be, in part, an adaptive trait. Here we investigated this idea and we found that subindividual variation of fruit size of Crataegus monogyna, in different populations throughout the latitudinal gradient in Europe, was explained at some extent by the selective pressures exerted by seed-dispersing birds. These findings support the hypothesis that within-individual variation in plants is an adaptive trait selected by interacting animals which may have important implications for plant evolution. PMID:24069297

  11. The use of agrobiodiversity for plant improvement and the intellectual property paradigm: institutional fit and legal tools for mass selection, conventional and molecular plant breeding.

    PubMed

    Batur, Fulya; Dedeurwaerdere, Tom

    2014-12-01

    Focused on the impact of stringent intellectual property mechanisms over the uses of plant agricultural biodiversity in crop improvement, the article delves into a systematic analysis of the relationship between institutional paradigms and their technological contexts of application, identified as mass selection, controlled hybridisation, molecular breeding tools and transgenics. While the strong property paradigm has proven effective in the context of major leaps forward in genetic engineering, it faces a systematic breakdown when extended to mass selection, where innovation often displays a collective nature. However, it also creates partial blockages in those innovation schemes rested between on-farm observation and genetic modification, i.e. conventional plant breeding and upstream molecular biology research tools. Neither overly strong intellectual property rights, nor the absence of well delineated protection have proven an optimal fit for these two intermediary socio-technological systems of cumulative incremental innovation. To address these challenges, the authors look at appropriate institutional alternatives which can create effective incentives for in situ agrobiodiversity conservation and the equitable distribution of technologies in plant improvement, using the flexibilities of the TRIPS Agreement, the liability rules set forth in patents or plant variety rights themselves (in the form of farmers', breeders' and research exceptions), and other ad hoc reward regimes. PMID:26085450

  12. The plant physical features selected by wildcats as signal posts: an economic approach to fecal marking

    NASA Astrophysics Data System (ADS)

    Piñeiro, Ana; Barja, Isabel

    2012-10-01

    The chemical signals of solitary and territorial felid species are essential for their intraspecific communication. We studied the selection of plant substrates during the fecal marking behavior of the European wildcat Felis silvestris from September 2008 to June 2009 in a protected area in Northwest Spain. The aim of the study was to examine the selection of plants as signal posts with respect to their physical characteristics. We hypothesized that wildcats deposit their fecal marks on plants with physical characteristics (e.g., size, species, and visual conspicuousness) that enhance the olfactory and visual effectiveness of the signal. Our results indicate that diameter, plant group, visual conspicuousness, and interaction between the diameter and plant group influence the decision of wildcats to deposit their fecal marks on plants. The wildcats chose plants with greater diameters and greater visual conspicuousness as scent-marking posts. Moreover, the wildcats chose woody and herbaceous plants, and certain plant species were marked more frequently than expected at random. Indeed, our results indicate that the fecal marks were not randomly distributed on the plants: the wildcats chose to place their marks on plants with certain physical characteristics that maximized the detectability of the signal by intruders and potential mates, thus facilitating the spatial distribution of the species.

  13. AFLP Genome Scanning Reveals Divergent Selection in Natural Populations of Liriodendron chinense (Magnoliaceae) along a Latitudinal Transect.

    PubMed

    Yang, Ai-Hong; Wei, Na; Fritsch, Peter W; Yao, Xiao-Hong

    2016-01-01

    Understanding adaptive genetic variation and its relation to environmental factors are important for understanding how plants adapt to climate change and for managing genetic resources. Genome scans for the loci exhibiting either notably high or low levels of population differentiation (outlier loci) provide one means of identifying genomic regions possibly associated with convergent or divergent selection. In this study, we combined Amplified Fragment Length Polymorphism (AFLP) genome scan and environmental association analysis to test for signals of natural selection in natural populations of Liriodendron chinense (Chinese Tulip Tree; Magnoliaceae) along a latitudinal transect. We genotyped 276 individuals from 11 populations of L. chinense using 987 AFLP markers. Both frequency-based (Dfdist and BayeScan) and correlation-based (MLM) methods were applied to detect outlier loci. Our analyses recovered both neutral and potentially adaptive genetic differentiation among populations of L. chinense. We found moderate genetic diversity within populations and high genetic differentiation among populations with reduced genetic diversity toward the periphery of the species ranges. Nine AFLP marker loci showed evidence of being outliers for population differentiation for both detection methods. Of these, six were strongly associated with at least one climate factor. Temperature, precipitation, and radiation were found to be three important factors influencing local adaptation of L. chinense. The outlier AFLP loci are likely not the target of natural selection, but the neighboring genes of these loci might be involved in local adaptation. Hence, these candidates should be validated by further studies. PMID:27303414

  14. AFLP Genome Scanning Reveals Divergent Selection in Natural Populations of Liriodendron chinense (Magnoliaceae) along a Latitudinal Transect

    PubMed Central

    Yang, Ai-Hong; Wei, Na; Fritsch, Peter W.; Yao, Xiao-Hong

    2016-01-01

    Understanding adaptive genetic variation and its relation to environmental factors are important for understanding how plants adapt to climate change and for managing genetic resources. Genome scans for the loci exhibiting either notably high or low levels of population differentiation (outlier loci) provide one means of identifying genomic regions possibly associated with convergent or divergent selection. In this study, we combined Amplified Fragment Length Polymorphism (AFLP) genome scan and environmental association analysis to test for signals of natural selection in natural populations of Liriodendron chinense (Chinese Tulip Tree; Magnoliaceae) along a latitudinal transect. We genotyped 276 individuals from 11 populations of L. chinense using 987 AFLP markers. Both frequency-based (Dfdist and BayeScan) and correlation-based (MLM) methods were applied to detect outlier loci. Our analyses recovered both neutral and potentially adaptive genetic differentiation among populations of L. chinense. We found moderate genetic diversity within populations and high genetic differentiation among populations with reduced genetic diversity toward the periphery of the species ranges. Nine AFLP marker loci showed evidence of being outliers for population differentiation for both detection methods. Of these, six were strongly associated with at least one climate factor. Temperature, precipitation, and radiation were found to be three important factors influencing local adaptation of L. chinense. The outlier AFLP loci are likely not the target of natural selection, but the neighboring genes of these loci might be involved in local adaptation. Hence, these candidates should be validated by further studies. PMID:27303414

  15. Identifying and Selecting Plants for the Landscape. Volume 23, Number 5.

    ERIC Educational Resources Information Center

    Rodekohr, Sherie; Harris, Clark Richard

    This handbook on identifying and selecting landscape plants can be used as a reference in landscaping courses or on an individual basis. The first of two sections, Identifying Plants for the Landscape, contains the following tables: shade tree identification; flowering tree identification; evergreen tree identification; flowering shrub…

  16. Soil, plant, and terrain effects on natural perchlorate distribution in a desert landscape.

    PubMed

    Andraski, B J; Jackson, W A; Welborn, T L; Böhlke, J K; Sevanthi, Ritesh; Stonestrom, D A

    2014-05-01

    Perchlorate (ClO) is a contaminant that occurs naturally throughout the world, but little is known about its distribution and interactions in terrestrial ecosystems. The objectives of this Amargosa Desert, Nevada study were to determine (i) the local-scale distribution of shallow-soil (0-30 cm) ClO with respect to shrub proximity (far and near) in three geomorphic settings (shoulder slope, footslope, and valley floor); (ii) the importance of soil, plant, and terrain variables on the hillslope-distribution of shallow-soil and creosote bush [ (Sessé & Moc. ex DC.) Coville] ClO; and (iii) atmospheric (wet plus dry, including dust) deposition of ClO in relation to soil and plant reservoirs and cycling. Soil ClO ranged from 0.3 to 5.0 μg kg. Within settings, valley floor ClO was 17× less near shrubs due in part to enhanced leaching, whereas shoulder and footslope values were ∼2× greater near shrubs. Hillslope regression models (soil, = 0.42; leaf, = 0.74) identified topographic and soil effects on ClO deposition, transport, and cycling. Selective plant uptake, bioaccumulation, and soil enrichment were evidenced by leaf ClO concentrations and Cl/ClO molar ratios that were ∼8000× greater and 40× less, respectively, than soil values. Atmospheric deposition ClO flux was 343 mg ha yr, ∼10× that for published southwestern wet-deposition fluxes. Creosote bush canopy ClO (1310 mg ha) was identified as a previously unrecognized but important and active reservoir. Nitrate δO analyses of atmospheric deposition and soil supported the leaf-cycled-ClO input hypothesis. This study provides basic data on ClO distribution and cycling that are pertinent to the assessment of environmental impacts in desert ecosystems and broadly transferable to anthropogenically contaminated systems. PMID:25602827

  17. 1000 Genomes Selection Browser 1.0: a genome browser dedicated to signatures of natural selection in modern humans.

    PubMed

    Pybus, Marc; Dall'Olio, Giovanni M; Luisi, Pierre; Uzkudun, Manu; Carreño-Torres, Angel; Pavlidis, Pavlos; Laayouni, Hafid; Bertranpetit, Jaume; Engelken, Johannes

    2014-01-01

    Searching for Darwinian selection in natural populations has been the focus of a multitude of studies over the last decades. Here we present the 1000 Genomes Selection Browser 1.0 (http://hsb.upf.edu) as a resource for signatures of recent natural selection in modern humans. We have implemented and applied a large number of neutrality tests as well as summary statistics informative for the action of selection such as Tajima's D, CLR, Fay and Wu's H, Fu and Li's F* and D*, XPEHH, ΔiHH, iHS, F(ST), ΔDAF and XPCLR among others to low coverage sequencing data from the 1000 genomes project (Phase 1; release April 2012). We have implemented a publicly available genome-wide browser to communicate the results from three different populations of West African, Northern European and East Asian ancestry (YRI, CEU, CHB). Information is provided in UCSC-style format to facilitate the integration with the rich UCSC browser tracks and an access page is provided with instructions and for convenient visualization. We believe that this expandable resource will facilitate the interpretation of signals of selection on different temporal, geographical and genomic scales. PMID:24275494

  18. Sex, death, and genetic variation: natural and sexual selection on cricket song

    PubMed Central

    Gray, D. A.; Cade, W. H.

    1999-01-01

    Male field crickets, Gryllus integer, in Texas, USA, produce a trilled calling song that attracts female crickets, resulting in enhanced mating success. Gravid female parasitoid flies, Ormia ochracea, are also attracted to male cricket calling song, resulting in the death of the male within about seven days. Using playbacks of field-cricket calling song in the natural habitat, we show that both female crickets and female parasitoid flies prefer male calling song with average numbers of pulses per trill. Thus female crickets exert stabilizing sexual selection, whereas flies exert disruptive natural selection on male song. Disruptive natural selection will promote genetic variation and population divergence. Stabilizing sexual selection will reduce genetic variation and maintain population cohesiveness. These forces may balance and together maintain the observed high levels of genetic variation (ca. 40%) in male calling song.

  19. Antagonistic natural and sexual selection on wing shape in a scrambling damselfly.

    PubMed

    Outomuro, David; Söderquist, Linus; Nilsson-Örtman, Viktor; Cortázar-Chinarro, María; Lundgren, Cecilia; Johansson, Frank

    2016-07-01

    Wings are a key trait underlying the evolutionary success of birds, bats, and insects. For over a century, researchers have studied the form and function of wings to understand the determinants of flight performance. However, to understand the evolution of flight, we must comprehend not only how morphology affects performance, but also how morphology and performance affect fitness. Natural and sexual selection can either reinforce or oppose each other, but their role in flight evolution remains poorly understood. Here, we show that wing shape is under antagonistic selection with regard to sexual and natural selection in a scrambling damselfly. In a field setting, natural selection (survival) favored individuals with long and slender forewings and short and broad hindwings. In contrast, sexual selection (mating success) favored individuals with short and broad forewings and narrow-based hindwings. Both types of selection favored individuals of intermediate size. These results suggest that individuals face a trade-off between flight energetics and maneuverability and demonstrate how natural and sexual selection can operate in similar directions for some wing traits, that is, wing size, but antagonistically for others, that is, wing shape. Furthermore, they highlight the need to study flight evolution within the context of species' mating systems and mating behaviors. PMID:27173835

  20. Darwin's principles of divergence and natural selection: Why Fodor was almost right.

    PubMed

    Richards, Robert J

    2012-03-01

    Darwin maintained that the principles of natural selection and divergence were the "keystones" of his theory. He introduced the principle of divergence to explain a fundamental feature of living nature: that organisms cluster into hierarchical groups, so as to be classifiable in the Linnaean taxonomic categories of variety, species, genus, and so on. Darwin's formulation of the principle of divergence, however, induces many perplexities. In his Autobiography, he claimed that he had neglected the problem of divergence in his Essay of 1844 and only solved it in a flash during a carriage ride in the 1850s; yet he does seem to have stated the problem in the Essay and provided the solution. This initial conundrum sets three questions I wish to pursue in this essay: (1) What is the relationship of the principle of divergence to that of natural selection? Is it independent of selection, derivative of selection, or a type of selection, perhaps comparable to sexual selection? (2) What is the advantage of divergence that the principle implies-that is, why is increased divergence beneficial in the struggle for life? And (3) What led Darwin to believe he had discovered the principle only in the 1850s? The resolution of these questions has implications for Darwin's other principle, natural selection, and permits us to readjust the common judgment made about Jerry Fodor's screed against that latter principle. PMID:22326095

  1. Plant functional traits and the multidimensional nature of species coexistence

    PubMed Central

    Kraft, Nathan J. B.; Godoy, Oscar; Levine, Jonathan M.

    2015-01-01

    Understanding the processes maintaining species diversity is a central problem in ecology, with implications for the conservation and management of ecosystems. Although biologists often assume that trait differences between competitors promote diversity, empirical evidence connecting functional traits to the niche differences that stabilize species coexistence is rare. Obtaining such evidence is critical because traits also underlie the average fitness differences driving competitive exclusion, and this complicates efforts to infer community dynamics from phenotypic patterns. We coupled field-parameterized mathematical models of competition between 102 pairs of annual plants with detailed sampling of leaf, seed, root, and whole-plant functional traits to relate phenotypic differences to stabilizing niche and average fitness differences. Single functional traits were often well correlated with average fitness differences between species, indicating that competitive dominance was associated with late phenology, deep rooting, and several other traits. In contrast, single functional traits were poorly correlated with the stabilizing niche differences that promote coexistence. Niche differences could only be described by combinations of traits, corresponding to differentiation between species in multiple ecological dimensions. In addition, several traits were associated with both fitness differences and stabilizing niche differences. These complex relationships between phenotypic differences and the dynamics of competing species argue against the simple use of single functional traits to infer community assembly processes but lay the groundwork for a theoretically justified trait-based community ecology. PMID:25561561

  2. ATP Binding Turns Plant Cryptochrome Into an Efficient Natural Photoswitch

    NASA Astrophysics Data System (ADS)

    Müller, Pavel; Bouly, Jean-Pierre; Hitomi, Kenichi; Balland, Véronique; Getzoff, Elizabeth D.; Ritz, Thorsten; Brettel, Klaus

    2014-06-01

    Cryptochromes are flavoproteins that drive diverse developmental light-responses in plants and participate in the circadian clock in animals. Plant cryptochromes have found application as photoswitches in optogenetics. We have studied effects of pH and ATP on the functionally relevant photoreduction of the oxidized FAD cofactor to the semi-reduced FADH. radical in isolated Arabidopsis cryptochrome 1 by transient absorption spectroscopy on nanosecond to millisecond timescales. In the absence of ATP, the yield of light-induced radicals strongly decreased with increasing pH from 6.5 to 8.5. With ATP present, these yields were significantly higher and virtually pH-independent up to pH 9. Analysis of our data in light of the crystallographic structure suggests that ATP-binding shifts the pKa of aspartic acid D396, the putative proton donor to FAD.-, from ~7.4 to >9, and favours a reaction pathway yielding long-lived aspartate D396-. Its negative charge could trigger conformational changes necessary for signal transduction.

  3. ATP binding turns plant cryptochrome into an efficient natural photoswitch.

    PubMed

    Müller, Pavel; Bouly, Jean-Pierre; Hitomi, Kenichi; Balland, Véronique; Getzoff, Elizabeth D; Ritz, Thorsten; Brettel, Klaus

    2014-01-01

    Cryptochromes are flavoproteins that drive diverse developmental light-responses in plants and participate in the circadian clock in animals. Plant cryptochromes have found application as photoswitches in optogenetics. We have studied effects of pH and ATP on the functionally relevant photoreduction of the oxidized FAD cofactor to the semi-reduced FADH(·) radical in isolated Arabidopsis cryptochrome 1 by transient absorption spectroscopy on nanosecond to millisecond timescales. In the absence of ATP, the yield of light-induced radicals strongly decreased with increasing pH from 6.5 to 8.5. With ATP present, these yields were significantly higher and virtually pH-independent up to pH 9. Analysis of our data in light of the crystallographic structure suggests that ATP-binding shifts the pKa of aspartic acid D396, the putative proton donor to FAD·(-), from ~7.4 to >9, and favours a reaction pathway yielding long-lived aspartate D396(-). Its negative charge could trigger conformational changes necessary for signal transduction. PMID:24898692

  4. Natural Selection

    ERIC Educational Resources Information Center

    Hall, Julie

    2006-01-01

    For education administrators, summer break is the time to regroup and prepare facilities for the next influx of students. Ensuring that facilities are equipped with proper furnishings is part of this preparation. Through careful research and planning, education administrators can choose furniture that will become a lasting investment. This article…

  5. Performance of five models to predict the naturalization of non-native woody plants in Iowa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of risk-assessment models that can predict the naturalization and invasion of non-native woody plants is a potentially beneficial approach for protecting human and natural environments. This study validates the power and accuracy of four risk-assessment models previously tested in Iowa, and exa...

  6. Air ingression calculations for selected plant transients using MELCOR

    SciTech Connect

    Kmetyk, L.N.

    1994-01-01

    Two sets of MELCOR calculations have been completed studying the effects of air ingression on the consequences of various severe accident scenarios. One set of calculations analyzed a station blackout with surge line failure prior to vessel breach, starting from nominal operating conditions; the other set of calculations analyzed a station blackout occurring during shutdown (refueling) conditions. Both sets of analyses were for the Surry plant, a three-loop Westinghouse PWR. For both accident scenarios, a basecase calculation was done, and then repeated with air ingression from containment into the core region following core degradation and vessel failure. In addition to the two sets of analyses done for this program, a similar air-ingression sensitivity study was done as part of a low-power/shutdown PRA, with results summarized here; that PRA study also analyzed a station blackout occurring during shutdown (refueling) conditions, but for the Grand Gulf plant, a BWR/6 with Mark III containment. These studies help quantify the amount of air that would have to enter the core region to have a significant impact on the severe accident scenario, and demonstrate that one effect, of air ingression is substantial enhancement of ruthenium release. These calculations also show that, while the core clad temperatures rise more quickly due to oxidation with air rather than steam, the core also degrades and relocates more quickly, so that no sustained, enhanced core heatup is predicted to occur with air ingression.

  7. ELECTROCHEMICAL FINGERPRINT STUDIES OF SELECTED MEDICINAL PLANTS RICH IN FLAVONOIDS.

    PubMed

    Konieczyński, Paweł

    2015-01-01

    The combination of a size-exclusion column (SEC) with electrochemical (voltammetric) detection at a boron-doped diamond electrode (BDDE) was applied for studying the correlations between electroactive Cu and Fe species with phenolic groups of flavonoids. For comparison with electrochemical results, SEC-HPLC-DAD detection was used. The studied plant material comprised of: Betula verrucosa Ehrh., Equisetun arvense L., Polygonum aviculare L., Viola tricolor L., Crataegus oxyacantha L., Sambucus nigra L. and Helichrysum arenarium (L.) Moench. Based upon the results, high negative correlation was found for the chromatographic peak currents at 45 min with the sum of Cu and Fe for the aqueous extracts of Sambucus, Crataegus and Betula species, and for the peak currents at 65 min of the aqueous extracts of Sambucus, Crataegus, Helichrysum and Betula botanical species. This behavior confirms that it is mainly the flavonoids with easily oxidizable phenolic groups which are strongly influenced by the presence of Cu and Fe. Moreover, the electrochemical profiles obtained thanks to the use of HPLC hyphenated with voltammetric detection can be potentially applied for fingerprint studies of the plant materials used in medicine. PMID:26647621

  8. Natural and planted flora of the log mountain surface - mined demonstration area, Bell County, Kentucky

    SciTech Connect

    Thompson, R.L.; Wade, G.L.; Straw, R.A.

    1996-12-31

    A descriptive study of the naturally invading and planted flora was conducted during 1984-1985 on a 14- and 21-year-old contour surface mine the 14.2 ha Log Mountain Demonstration Area (LMDA), in Bell County, Kentucky. Six habitats are designated from areas created from coal mining; the 1963 bench, 1970 bench, bench highwalls, mine outslopes, mine seeps, and coal haul-telephone microwave tower road. Twenty-four of 25 woody and herbaceous species (11 indigenous, 13 non-indigenous) have persisted from plantings by personnel of the Northeastern Forest Experiment Station, USDA Forest Service. We recommend 11 native and exotic woody and herbaceous species for planting on coal surface-mined areas. An annotated list of vascular plants comprises 360 taxa (286 indigenous, 74 non-indigenous) in 224 genera from 82 families. Taxa consist of 1 Lycopodiophyta, 1 Equisetophyta, 8 Polypodiophyta, 7 Pinophyta, and 343 Magnoliophyta. The most species-rich families are the Asteraceae (64), Poaceae (39), Fabaceae (20), Cyperaceae (16), Rosaceae (13), and Lamiaceae (11). A total of 155 Bell County distribution records were documented. Three threatened Kentucky species (Gentiana decora, Liparis loeselii, Silene ovata) were present in refugial habitats created by surface mining. The high species richness has resulted from native and naturalized invading species from the environs, native and exotic planted species, and species from the remnant seed bank. Forest vegetation is a complex mosaic of natural and semi-natural plant communities on the unplanted and planted areas of LMDA.

  9. Can selection to escape nectar thieving force plants to portion nectar in many flowers?

    NASA Astrophysics Data System (ADS)

    Pettersson, Mats W.

    1999-02-01

    There are several hypotheses which try to explain why particular plants produce just the number of flowers that they do. These hypotheses include: compromises between the attraction of pollinators and avoiding self-pollination by geitonogamy; optimal nectar production as a result of diminishing gains of nectar production; opportunity for selective abortion; or different bet-hedging strategies. In this paper, I present a hypothesis which interferes with the others concerning flower numbers in plants: nectar thieving can apply a selection force in plants which result in a portioning of nectar in many flowers. Energy saved by reducing the quantity of nectar in each flower can be directed into greater flower numbers.

  10. Grasshopper host-plant selection influences seedling recruitment of native plants in an exotic dominated grassland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crested wheatgrass (Agropyron cristatum) is the most common exotic grass in western North America. Areas planted to crested wheatgrass are resistant to colonization by native plant species and often remain relatively stable for decades, imposing problems for the restoration of native grasslands. Gra...

  11. Modern plant metabolomics: advanced natural product gene discoveries, improved technologies, and future prospects.

    PubMed

    Sumner, Lloyd W; Lei, Zhentian; Nikolau, Basil J; Saito, Kazuki

    2015-02-01

    Plant metabolomics has matured and modern plant metabolomics has accelerated gene discoveries and the elucidation of a variety of plant natural product biosynthetic pathways. This review covers the approximate period of 2000 to 2014, and highlights specific examples of the discovery and characterization of novel genes and enzymes associated with the biosynthesis of natural products such as flavonoids, glucosinolates, terpenoids, and alkaloids. Additional examples of the integration of metabolomics with genome-based functional characterizations of plant natural products that are important to modern pharmaceutical technology are also reviewed. This article also provides a substantial review of recent technical advances in mass spectrometry imaging, nuclear magnetic resonance imaging, integrated LC-MS-SPE-NMR for metabolite identifications, and X-ray crystallography of microgram quantities for structural determinations. The review closes with a discussion on the future prospects of metabolomics related to crop species and herbal medicine. PMID:25342293

  12. Modern plant metabolomics: Advanced natural product gene discoveries, improved technologies, and future prospects

    SciTech Connect

    Sumner, Lloyd W.; Lei, Zhentian; Nikolau, Basil J.; Saito, Kazuki

    2014-10-24

    Plant metabolomics has matured and modern plant metabolomics has accelerated gene discoveries and the elucidation of a variety of plant natural product biosynthetic pathways. This study highlights specific examples of the discovery and characterization of novel genes and enzymes associated with the biosynthesis of natural products such as flavonoids, glucosinolates, terpenoids, and alkaloids. Additional examples of the integration of metabolomics with genome-based functional characterizations of plant natural products that are important to modern pharmaceutical technology are also reviewed. This article also provides a substantial review of recent technical advances in mass spectrometry imaging, nuclear magnetic resonance imaging, integrated LC-MS-SPE-NMR for metabolite identifications, and x-ray crystallography of microgram quantities for structural determinations. The review closes with a discussion on the future prospects of metabolomics related to crop species and herbal medicine.

  13. Modern plant metabolomics: Advanced natural product gene discoveries, improved technologies, and future prospects

    DOE PAGESBeta

    Sumner, Lloyd W.; Lei, Zhentian; Nikolau, Basil J.; Saito, Kazuki

    2014-10-24

    Plant metabolomics has matured and modern plant metabolomics has accelerated gene discoveries and the elucidation of a variety of plant natural product biosynthetic pathways. This study highlights specific examples of the discovery and characterization of novel genes and enzymes associated with the biosynthesis of natural products such as flavonoids, glucosinolates, terpenoids, and alkaloids. Additional examples of the integration of metabolomics with genome-based functional characterizations of plant natural products that are important to modern pharmaceutical technology are also reviewed. This article also provides a substantial review of recent technical advances in mass spectrometry imaging, nuclear magnetic resonance imaging, integrated LC-MS-SPE-NMR formore » metabolite identifications, and x-ray crystallography of microgram quantities for structural determinations. The review closes with a discussion on the future prospects of metabolomics related to crop species and herbal medicine.« less

  14. Genomic selection for quantitative adult plant stem rust resistance in wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantitative adult plant resistance (APR) to stem rust (Puccinia graminis f. sp. tritici) is an important breeding target in wheat (Triticum aestivum L.) and a potential target for genomic selection (GS). To evaluate the relative importance of known APR loci in applying genomic selection, we charact...

  15. Experimental infection of plants with an herbivore-associated bacterial endosymbiont influences herbivore host selection behavior

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although bacterial endosymbioses are common among phloeophagous herbivores, little is known regarding the effects of symbionts on herbivore host selection and population dynamics. We tested the hypothesis that plant selection and reproductive performance by a phloem-feeding herbivore (potato psyllid...

  16. Determining the Effect of Natural Selection on Linked Neutral Divergence across Species

    PubMed Central

    Phung, Tanya N.; Lohmueller, Kirk E.

    2016-01-01

    A major goal in evolutionary biology is to understand how natural selection has shaped patterns of genetic variation across genomes. Studies in a variety of species have shown that neutral genetic diversity (intra-species differences) has been reduced at sites linked to those under direct selection. However, the effect of linked selection on neutral sequence divergence (inter-species differences) remains ambiguous. While empirical studies have reported correlations between divergence and recombination, which is interpreted as evidence for natural selection reducing linked neutral divergence, theory argues otherwise, especially for species that have diverged long ago. Here we address these outstanding issues by examining whether natural selection can affect divergence between both closely and distantly related species. We show that neutral divergence between closely related species (e.g. human-primate) is negatively correlated with functional content and positively correlated with human recombination rate. We also find that neutral divergence between distantly related species (e.g. human-rodent) is negatively correlated with functional content and positively correlated with estimates of background selection from primates. These patterns persist after accounting for the confounding factors of hypermutable CpG sites, GC content, and biased gene conversion. Coalescent models indicate that even when the contribution of ancestral polymorphism to divergence is small, background selection in the ancestral population can still explain a large proportion of the variance in divergence across the genome, generating the observed correlations. Our findings reveal that, contrary to previous intuition, natural selection can indirectly affect linked neutral divergence between both closely and distantly related species. Though we cannot formally exclude the possibility that the direct effects of purifying selection drive some of these patterns, such a scenario would be possible only

  17. Determining the Effect of Natural Selection on Linked Neutral Divergence across Species.

    PubMed

    Phung, Tanya N; Huber, Christian D; Lohmueller, Kirk E

    2016-08-01

    A major goal in evolutionary biology is to understand how natural selection has shaped patterns of genetic variation across genomes. Studies in a variety of species have shown that neutral genetic diversity (intra-species differences) has been reduced at sites linked to those under direct selection. However, the effect of linked selection on neutral sequence divergence (inter-species differences) remains ambiguous. While empirical studies have reported correlations between divergence and recombination, which is interpreted as evidence for natural selection reducing linked neutral divergence, theory argues otherwise, especially for species that have diverged long ago. Here we address these outstanding issues by examining whether natural selection can affect divergence between both closely and distantly related species. We show that neutral divergence between closely related species (e.g. human-primate) is negatively correlated with functional content and positively correlated with human recombination rate. We also find that neutral divergence between distantly related species (e.g. human-rodent) is negatively correlated with functional content and positively correlated with estimates of background selection from primates. These patterns persist after accounting for the confounding factors of hypermutable CpG sites, GC content, and biased gene conversion. Coalescent models indicate that even when the contribution of ancestral polymorphism to divergence is small, background selection in the ancestral population can still explain a large proportion of the variance in divergence across the genome, generating the observed correlations. Our findings reveal that, contrary to previous intuition, natural selection can indirectly affect linked neutral divergence between both closely and distantly related species. Though we cannot formally exclude the possibility that the direct effects of purifying selection drive some of these patterns, such a scenario would be possible only

  18. A highly selective biosynthetic pathway to non-natural C50 carotenoids assembled from moderately selective enzymes.

    PubMed

    Furubayashi, Maiko; Ikezumi, Mayu; Takaichi, Shinichi; Maoka, Takashi; Hemmi, Hisashi; Ogawa, Takuya; Saito, Kyoichi; Tobias, Alexander V; Umeno, Daisuke

    2015-01-01

    Synthetic biology aspires to construct natural and non-natural pathways to useful compounds. However, pathways that rely on multiple promiscuous enzymes may branch, which might preclude selective production of the target compound. Here, we describe the assembly of a six-enzyme pathway in Escherichia coli for the synthesis of C50-astaxanthin, a non-natural purple carotenoid. We show that by judicious matching of engineered size-selectivity variants of the first two enzymes in the pathway, farnesyl diphosphate synthase (FDS) and carotenoid synthase (CrtM), branching and the production of non-target compounds can be suppressed, enriching the proportion of C50 backbones produced. We then further extend the C50 pathway using evolved or wild-type downstream enzymes. Despite not containing any substrate- or product-specific enzymes, the resulting pathway detectably produces only C50 carotenoids, including ∼ 90% C50-astaxanthin. Using this approach, highly selective pathways can be engineered without developing absolutely specific enzymes. PMID:26168783

  19. A highly selective biosynthetic pathway to non-natural C50 carotenoids assembled from moderately selective enzymes

    PubMed Central

    Furubayashi, Maiko; Ikezumi, Mayu; Takaichi, Shinichi; Maoka, Takashi; Hemmi, Hisashi; Ogawa, Takuya; Saito, Kyoichi; Tobias, Alexander V; Umeno, Daisuke

    2015-01-01

    Synthetic biology aspires to construct natural and non-natural pathways to useful compounds. However, pathways that rely on multiple promiscuous enzymes may branch, which might preclude selective production of the target compound. Here, we describe the assembly of a six-enzyme pathway in Escherichia coli for the synthesis of C50-astaxanthin, a non-natural purple carotenoid. We show that by judicious matching of engineered size-selectivity variants of the first two enzymes in the pathway, farnesyl diphosphate synthase (FDS) and carotenoid synthase (CrtM), branching and the production of non-target compounds can be suppressed, enriching the proportion of C50 backbones produced. We then further extend the C50 pathway using evolved or wild-type downstream enzymes. Despite not containing any substrate- or product-specific enzymes, the resulting pathway detectably produces only C50 carotenoids, including ∼90% C50-astaxanthin. Using this approach, highly selective pathways can be engineered without developing absolutely specific enzymes. PMID:26168783

  20. Natural genetic variation for morphological and molecular determinants of plant growth and yield.

    PubMed

    Nunes-Nesi, Adriano; Nascimento, Vitor de Laia; de Oliveira Silva, Franklin Magnum; Zsögön, Agustin; Araújo, Wagner L; Sulpice, Ronan

    2016-05-01

    The rates of increase in yield of the main commercial crops have been steadily falling in many areas worldwide. This generates concerns because there is a growing demand for plant biomass due to the increasing population. Plant yield should thus be improved in the context of climate change and decreasing natural resources. It is a major challenge which could be tackled by improving and/or altering light-use efficiency, CO2 uptake and fixation, primary metabolism, plant architecture and leaf morphology, and developmental plant processes. In this review, we discuss some of the traits which could lead to yield increase, with a focus on how natural genetic variation could be harnessed. Moreover, we provide insights for advancing our understanding of the molecular aspects governing plant growth and yield, and propose future avenues for improvement of crop yield. We also suggest that knowledge accumulated over the last decade in the field of molecular physiology should be integrated into new ideotypes. PMID:27012286

  1. Natural soil microbes alter flowering phenology and the intensity of selection on flowering time in a wild Arabidopsis relative

    PubMed Central

    Wagner, Maggie R.; Lundberg, Derek S.; Coleman-Derr, Devin; Tringe, Susannah G.; Dangl, Jeffery L.; Mitchell-Olds, Thomas

    2014-01-01

    Plant phenology is known to depend on many different environmental variables, but soil microbial communities have rarely been acknowledged as possible drivers of flowering time. Here we tested separately the effects of four naturally occurring soil microbiomes and their constituent soil chemistries on flowering phenology and reproductive fitness of Boechera stricta, a wild relative of Arabidopsis. Flowering time was sensitive to both microbes and the abiotic properties of different soils; varying soil microbiota also altered patterns of selection on flowering time. Thus, soil microbes potentially contribute to phenotypic plasticity of flowering time and to differential selection observed between habitats. We also describe a method to dissect the microbiome into single axes of variation that can help identify candidate organisms whose abundance in soil correlates with flowering time. This approach is broadly applicable to search for microbial community members that alter biological characteristics of interest. PMID:24698177

  2. Darwin and his pigeons. The analogy between artificial and natural selection revisited.

    PubMed

    Theunissen, Bert

    2012-01-01

    The analogy between artificial selection of domestic varieties and natural selection in nature was a vital element of Darwin's argument in his Origin of Species. Ever since, the image of breeders creating new varieties by artificial selection has served as a convincing illustration of how the theory works. In this paper I argue that we need to reconsider our understanding of Darwin's analogy. Contrary to what is often assumed, nineteenth-century animal breeding practices constituted a highly controversial field that was fraught with difficulties. It was only with considerable effort that Darwin forged his analogy, and he only succeeded by downplaying the importance of two other breeding techniques - crossing of varieties and inbreeding - that many breeders deemed essential to obtain new varieties. Part of the explanation for Darwin's gloss on breeding practices, I shall argue, was that the methods of his main informants, the breeders of fancy pigeons, were not representative of what went on in the breeding world at large. Darwin seems to have been eager to take the pigeon fanciers at their word, however, as it was only their methods that provided him with the perfect analogy with natural selection. Thus while his studies of domestic varieties were important for the development of the concept of natural selection, the reverse was also true: Darwin's comprehension of breeding practices was moulded by his understanding of the working of natural selection in nature. Historical studies of domestic breeding practices in the eighteenth and nineteenth century confirm that, besides selection, the techniques of inbreeding and crossing were much more important than Darwin's interpretation allowed for. And they still are today. This calls for a reconsideration of the pedagogic use of Darwin's analogy too. PMID:22037999

  3. Chemo- and Site-Selective Derivatizations of Natural Products Enabling Biological Studies

    PubMed Central

    Robles, Omar

    2014-01-01

    Bioactive natural products and derivatives remain an enduring starting point for the discovery of new cellular targets for disease intervention and lead compounds for the development of new therapeutic agents. The former goal is accomplished through the synthesis of bioactive cellular probes from natural products enabling insights into the mechanism of action of these natural products by classical affinity chromatography or more recent proteome profiling methods. However, the direct and selective modification of native natural products for these purposes remains a challenge due to the structural complexity and the wide functional group diversity found in these natural substances. The lack of selective synthetic methods available to directly manipulate unprotected complex small molecules, in particular to perform structure-activity relationship studies and prepare appropriate cellular probes, has recently begun to be addressed benefitting from the broader emerging area of chemoselective synthetic methodology. Thus, new reagents, catalysts and reaction processes are enabling both chemo- and site-selective modifications of complex, native natural products. In this review, we describe selected recent examples of these functionalization strategies in this emerging area. PMID:24468713

  4. Chemo- and site-selective derivatizations of natural products enabling biological studies.

    PubMed

    Robles, Omar; Romo, Daniel

    2014-03-01

    Bioactive natural products and derivatives remain an enduring starting point for the discovery of new cellular targets for disease intervention and lead compounds for the development of new therapeutic agents. The former goal is accomplished through the synthesis of bioactive cellular probes from natural products, enabling insights into the mechanism of action of these natural products by classical affinity chromatography or more recent proteome profiling methods. However, the direct and selective modification of native natural products for these purposes remains a challenge due to the structural complexity and the wide functional group diversity found in these natural substances. The lack of selective synthetic methods available to directly manipulate unprotected complex small molecules, in particular to perform structure-activity relationship studies and prepare appropriate cellular probes, has recently begun to be addressed, benefitting from the broader emerging area of chemoselective synthetic methodology. Thus, new reagents, catalysts and reaction processes are enabling both chemo- and site-selective modifications of complex, native natural products. In this review, we describe selected recent examples of these functionalization strategies in this emerging area. PMID:24468713

  5. Genetic evidence for natural selection in humans in the contemporary United States.

    PubMed

    Beauchamp, Jonathan P

    2016-07-12

    Recent findings from molecular genetics now make it possible to test directly for natural selection by analyzing whether genetic variants associated with various phenotypes have been under selection. I leverage these findings to construct polygenic scores that use individuals' genotypes to predict their body mass index, educational attainment (EA), glucose concentration, height, schizophrenia, total cholesterol, and (in females) age at menarche. I then examine associations between these scores and fitness to test whether natural selection has been occurring. My study sample includes individuals of European ancestry born between 1931 and 1953 who participated in the Health and Retirement Study, a representative study of the US population. My results imply that natural selection has been slowly favoring lower EA in both females and males, and are suggestive that natural selection may have favored a higher age at menarche in females. For EA, my estimates imply a rate of selection of about -1.5 mo of education per generation (which pales in comparison with the increases in EA observed in contemporary times). Although they cannot be projected over more than one generation, my results provide additional evidence that humans are still evolving-albeit slowly, especially compared with the rapid changes that have occurred over the past few generations due to cultural and environmental factors. PMID:27402742

  6. Below Regulatory Concern Owners Group: Selection of plants for sampling program: Final report

    SciTech Connect

    Vance, J.N.

    1988-03-01

    This report is one of a series of reports in the EPRI Below Regulatory Concern (BRC) program. This study was performed to provide the selection basis for plants to be included in the BRC sampling program. This final report describes the evaluations performed using 10CFR61 data and current fuel performance data to identify those plants with larger quantities of tramp or exposed fuel and correspondingly higher transuranic levels in the plant waste streams. Plants were ranked from the highest level to the lowest level of exposed or tramp fuel in the core. 10 tabs.

  7. Phytohormonal basis for the plant growth promoting action of naturally occurring biostimulators.

    PubMed

    Kurepin, Leonid V; Zaman, Mohammad; Pharis, Richard P

    2014-07-01

    There is increasing interest in the use of naturally occurring 'biostimulators' for enhancing the growth of agricultural and horticultural crops. Bacteria, fungi and protozoa, as well as marine algae-based seaweed extracts, can produce or contain biostimulators. The activity of biostimulators to promote plant growth is often attributed to their ability to directly or indirectly provide mineral nutrients (mostly N, but also P, S and other macro- and micro-nutrients) to plants. Alternatively, biostimulators are postulated to increase the plant's ability to assimilate these mineral nutrients, often in return for photo-assimilates (as occurs with certain bacteria and fungi associations). Although optimal growth of plants depends on the availability of adequate mineral nutritients, that growth (and also development, including reproduction) is also regulated by plant hormones (phytohormones), including gibberellins, auxins and cytokinins. This review describes and discusses the evidence that the presence or application of biostimulators also increases plant growth directly via phytohormone action and also influences the plant's ability to control its own hormone biosynthesis and homeostasis. Finally, it discusses the need for a better understanding of the role(s) that are played by the naturally occurring biostimulators associated with the plant in the crop field. It is suggested that better understanding will allow for optimal crop yield returns, since disruptions of phytohormone homeostasis in plant organs and tissues can yield either beneficial or sub-optimal outcomes. PMID:24375470

  8. Genome-guided investigation of plant natural product biosynthesis.

    PubMed

    Kellner, Franziska; Kim, Jeongwoon; Clavijo, Bernardo J; Hamilton, John P; Childs, Kevin L; Vaillancourt, Brieanne; Cepela, Jason; Habermann, Marc; Steuernagel, Burkhard; Clissold, Leah; McLay, Kirsten; Buell, Carol Robin; O'Connor, Sarah E

    2015-05-01

    The medicinal plant Madagascar periwinkle, Catharanthus roseus (L.) G. Don, produces hundreds of biologically active monoterpene-derived indole alkaloid (MIA) metabolites and is the sole source of the potent, expensive anti-cancer compounds vinblastine and vincristine. Access to a genome sequence would enable insights into the biochemistry, control, and evolution of genes responsible for MIA biosynthesis. However, generation of a near-complete, scaffolded genome is prohibitive to small research communities due to the expense, time, and expertise required. In this study, we generated a genome assembly for C. roseus that provides a near-comprehensive representation of the genic space that revealed the genomic context of key points within the MIA biosynthetic pathway including physically clustered genes, tandem gene duplication, expression sub-functionalization, and putative neo-functionalization. The genome sequence also facilitated high resolution co-expression analyses that revealed three distinct clusters of co-expression within the components of the MIA pathway. Coordinated biosynthesis of precursors and intermediates throughout the pathway appear to be a feature of vinblastine/vincristine biosynthesis. The C. roseus genome also revealed localization of enzyme-rich genic regions and transporters near known biosynthetic enzymes, highlighting how even a draft genome sequence can empower the study of high-value specialized metabolites. PMID:25759247

  9. A reliable method for the selection and confirmation of transconjugants of plant growth-promoting bacteria especially plant-associated Burkholderia spp.

    PubMed

    Tariq, Mohsin; Lum, Michelle R; Chong, Allan W; Amirapu, Anjana B; Hameed, Sohail; Hirsch, Ann M

    2015-10-01

    Selectable markers, e.g., antibiotic resistance, for conjugation experiments are not always effective for slow-growing plant growth promoting bacteria such as Burkholderia. We used PCAT medium containing Congo Red for selecting Burkholderia transconjugants. This method allows for the reliable selection of transconjugants of these novel plant growth-promoting bacteria. PMID:26187775

  10. Selective Aptamers for Detection of Estradiol and Ethynylestradiol in Natural Waters.

    PubMed

    Akki, Spurti U; Werth, Charles J; Silverman, Scott K

    2015-08-18

    We used in vitro selection to identify new DNA aptamers for two endocrine-disrupting compounds often found in treated and natural waters, 17β-estradiol (E2) and 17α-ethynylestradiol (EE). We used equilibrium filtration to determine aptamer sensitivity/selectivity and dimethyl sulfate (DMS) probing to explore aptamer binding sites. The new E2 aptamers are at least 74-fold more sensitive for E2 than is a previously reported DNA aptamer, with dissociation constants (Kd values) of 0.6 μM. Similarly, the EE aptamers are highly sensitive for EE, with Kd of 0.5-1.0 μM. Selectivity values indicate that the E2 aptamers bind E2 and a structural analogue, estrone (E1), equally well and are up to 74-fold selective over EE. One EE aptamer is 53-fold more selective for EE over E2 or E1, but the other binds EE, E2, and E1 with similar affinity. The new aptamers do not lose sensitivity or selectivity in natural water from a local lake, despite the presence of natural organic matter (∼4 mg/L TOC). DMS probing suggests that E2 binding occurs in relatively flexible single-stranded DNA regions, an important finding for rational redesign of aptamers and their incorporation into sensing platforms. This is the first report of aptamers with strong selectivity for E2 and E1 over EE, or with strong selectivity for EE over E2 and E1. Such selectivity is important for achieving the goal of creating practically useful DNA-based sensors that can distinguish structurally similar estrogenic compounds in natural waters. PMID:26182235

  11. Herbicidal agents from actinomycetes against selected crop plants and weeds.

    PubMed

    Dhanasekaran, Dharumadurai; Thajuddin, Nooruddin; Panneerselvam, Annamalai

    2010-04-01

    About 64 total actinomycetes were isolated from various coastal soils. Sixteen actinomycete isolates were screened for herbicidal principles. Out of these, five potent isolates were selected for characterisation and identification. Based on their morphological, biochemical and physiological characteristics, the actinomycete isolates were identified as Glyomyces, Saccharomonospra and Streptomyces sp. The Streptomycetes isolates were tested for herbicidal principles by germination inhibition assay. About 10 crop seeds were tested for herbicidal activity with Streptomycetes isolates. The crop seeds did not show growth inhibition. Four weed seeds were tested for herbicidal activity with Streptomyces isolates. Streptomyces inhibits the growth of Echinochilora crusgalli, but it could not inhibit the growth of Echinochilora colonum, Parthenium sp., or Ageratum conizoites. The present study concludes that Streptomyces isolates will be a bioherbicide against E. crusgalli. Further study is required to confirm the activity of Streptomyces isolates against E. crusgalli under field conditions. PMID:20182949

  12. Image statistics underlying natural texture selectivity of neurons in macaque V4

    PubMed Central

    Okazawa, Gouki; Tajima, Satohiro; Komatsu, Hidehiko

    2015-01-01

    Our daily visual experiences are inevitably linked to recognizing the rich variety of textures. However, how the brain encodes and differentiates a plethora of natural textures remains poorly understood. Here, we show that many neurons in macaque V4 selectively encode sparse combinations of higher-order image statistics to represent natural textures. We systematically explored neural selectivity in a high-dimensional texture space by combining texture synthesis and efficient-sampling techniques. This yielded parameterized models for individual texture-selective neurons. The models provided parsimonious but powerful predictors for each neuron’s preferred textures using a sparse combination of image statistics. As a whole population, the neuronal tuning was distributed in a way suitable for categorizing textures and quantitatively predicts human ability to discriminate textures. Together, we suggest that the collective representation of visual image statistics in V4 plays a key role in organizing the natural texture perception. PMID:25535362

  13. Reassessment of selected factors affecting siting of Nuclear Power Plants

    SciTech Connect

    Davis, R.E.; Hanson, A.L.; Mubayi, V.; Nourbakhsh, H.P.

    1997-02-01

    Brookhaven National Laboratory has performed a series of probabilistic consequence assessment calculations for nuclear reactor siting. This study takes into account recent insights into severe accident source terms and examines consequences in a risk based format consistent with the quantitative health objectives (QHOs) of the NRC`s Safety Goal Policy. Simplified severe accident source terms developed in this study are based on the risk insights of NUREG-1150. The results of the study indicate that both the quantity of radioactivity released in a severe accident as well as the likelihood of a release are lower than those predicted in earlier studies. The accident risks using the simplified source terms are examined at a series of generic plant sites, that vary in population distribution, meteorological conditions, and exclusion area boundary distances. Sensitivity calculations are performed to evaluate the effects of emergency protective action assumptions on the risk of prompt fatality and latent cancers fatality, and population relocation. The study finds that based on the new source terms the prompt and latent fatality risks at all generic sites meet the QHOs of the NRC`s Safety Goal Policy by margins ranging from one to more than three orders of magnitude. 4 refs., 17 figs., 24 tabs.

  14. Two-flow simulation of the natural light field within a canopy of submerged aquatic plants

    NASA Technical Reports Server (NTRS)

    Ackleson, S. G.; Klemas, V.

    1986-01-01

    A two-flow model is developed to simulate a light field composed of both collimated and diffuse irradiance within natural waters containing a canopy of bottom-adhering plants. To account for the effects of submerging a canopy, the transmittance and reflectance terms associated with each plant structure (leaves, stems, fruiting bodies, etc.) are expressed as functions of the ratio of the refractive index of the plant material to the refractive index of the surrounding media and the internal transmittance of the plant stucture. Algebraic solutions to the model are shown to yield plausible physical explanations for unanticipated variations in volume reflectance spectra. The effect of bottom reflectance on the near-bottom light field is also investigated. These indicate that within light-limited submerged aquatic plant canopies, substrate reflectance may play an important role in determining the amount of light available to the plants and, therefore, canopy productivity.

  15. Anthocyanins as antimicrobial agents of natural plant origin.

    PubMed

    Cisowska, Agnieszka; Wojnicz, Dorota; Hendrich, Andrzej B

    2011-01-01

    Anthocyanins are particularly abundant in different fruits, especially in berries. The beneficial effects of these compounds for human health have been known from at least the 16th century. Despite the great number of papers devoted to the different biological effects exerted by anthocyanins only a limited number of studies is focused on the antimicrobial activity of these compounds. Anthocyanin content of berry fruits varies from 7.5 mg/100 mg fresh fruit in redcurrant (Ribes rubum) up to 460 mg/100 g fresh fruit in chokeberry (Aronia melanocarpa). After consumption, anthocyanins are intensively metabolized, mainly in the intestines and liver. Glucorination, methylation and sulfation are the most typical metabolic reactions. Antimicrobial activity of crude extracts of plant phenolic compounds against human pathogens has been intensively studied to characterize and develop new healthy food ingredients as well as medical and pharmaceutical products. However, there is very little information available about the antimicrobial activity of the pure anthocyanins. In the last part of this review we present the collection of papers describing the anthocyanin profiles of different fruits (mainly berries) and the antimicrobial properties of the identified compounds. Generally, anthocyanins are active against different microbes, however Gram-positive bacteria usually are more susceptible to the anthocyanin action than Gram-negative ones. Mechanisms underlying anthocyanin activity include both membrane and intracellular interactions of these compounds. Antimicrobial activity of berries and other anthocyanin-containing fruits is likely to be caused by multiple mechanisms and synergies because they contain various compounds including anthocyanins, weak organic acids, phenolic acids, and their mixtures of different chemical forms. Therefore, the antimicrobial effect of chemically complex compounds has to be critically analyzed. PMID:21366068

  16. Performance Diagnosis using Optical Torque Sensor for Selection of a Steam Supply Plant among Advanced Combined Cycle Power Plants

    NASA Astrophysics Data System (ADS)

    Umezawa, Shuichi

    A newly developed optical torque sensor was applied to select a steam supply plant among advanced combined cycle, i.e. ACC, power plants of the Tokyo Electric Power Company. The sensor uses laser beams focused on small stainless steel reflectors having bar-code patterns attached on the surface of the rotating shaft, and a technique of signal processing using a correlation function featuring high frequency. The plant that supplied steam was selected on the basis of diagnosis of each steam turbine performance of the plants. Heat balance program was developed to analyze steam turbine performance using data of turbine output measured by the torque sensor and data measured by existing instruments of the power station. The steam turbine that supplied steam was determined by the present method using the optical torque sensor. The accuracy of the method to determine the steam supply plant was analyzed. It was then confirmed that the accuracy was greatly improved as compared with that of existing method.

  17. The interaction of sexually and naturally selected traits in the adaptive radiations of cichlid fishes.

    PubMed

    Salzburger, Walter

    2009-01-01

    The question of how genetic variation translates into organismal diversity has puzzled biologists for decades. Despite recent advances in evolutionary and developmental genetics, the mechanisms that underlie adaptation, diversification and evolutionary innovation remain largely unknown. The exceptionally diverse species flocks of cichlid fishes are textbook examples of adaptive radiation and explosive speciation and emerge as powerful model systems to study the genetic basis of animal diversification. East Africa's hundreds of endemic cichlid species are akin to a natural mutagenesis screen and differ greatly not only in ecologically relevant (hence naturally selected) characters such as mouth morphology and body shape, but also in sexually selected traits such as coloration. One of the most fascinating aspects of cichlid evolution is the frequent occurrence of evolutionary parallelisms, which has led to the question whether selection alone is sufficient to produce these parallel morphologies, or whether a developmental or genetic bias has influenced the direction of diversification. Here, I review fitness-relevant traits that could be responsible for the cichlids' evolutionary success and assess whether these were shaped by sexual or natural selection. I then focus on the interaction and the relative importance of sexual vs. natural selection in cichlid evolution. Finally, I discuss what is currently known about the genes underlying the morphogenesis of adaptively relevant traits and highlight the importance of the forthcoming cichlid genomes in the quest of the genetic basis of diversification in this group. PMID:18992003

  18. Are heritability and selection related to population size in nature? Meta-analysis and conservation implications.

    PubMed

    Wood, Jacquelyn L A; Yates, Matthew C; Fraser, Dylan J

    2016-06-01

    It is widely thought that small populations should have less additive genetic variance and respond less efficiently to natural selection than large populations. Across taxa, we meta-analytically quantified the relationship between adult census population size (N) and additive genetic variance (proxy: h (2)) and found no reduction in h (2) with decreasing N; surveyed populations ranged from four to one million individuals (1735 h (2) estimates, 146 populations, 83 species). In terms of adaptation, ecological conditions may systematically differ between populations of varying N; the magnitude of selection these populations experience may therefore also differ. We thus also meta-analytically tested whether selection changes with N and found little evidence for systematic differences in the strength, direction or form of selection with N across different trait types and taxa (7344 selection estimates, 172 populations, 80 species). Collectively, our results (i) indirectly suggest that genetic drift neither overwhelms selection more in small than in large natural populations, nor weakens adaptive potential/h (2) in small populations, and (ii) imply that natural populations of varying sizes experience a variety of environmental conditions, without consistently differing habitat quality at small N. However, we caution that the data are currently insufficient to determine whether some small populations may retain adaptive potential definitively. Further study is required into (i) selection and genetic variation in completely isolated populations of known N, under-represented taxonomic groups, and nongeneralist species, (ii) adaptive potential using multidimensional approaches and (iii) the nature of selective pressures for specific traits. PMID:27247616

  19. Anthocyanin production as a potential visual selection marker during plant transformation.

    PubMed

    Kortstee, A J; Khan, S A; Helderman, C; Trindade, L M; Wu, Y; Visser, R G F; Brendolise, C; Allan, A; Schouten, H J; Jacobsen, E

    2011-12-01

    A mutant allele of the transcription factor gene MYB10 from apple induces anthocyanin production throughout the plant. This gene, including its upstream promoter, gene coding region and terminator sequence, was introduced into apple, strawberry and potato plants to determine whether it could be used as a visible selectable marker for plant transformation as an alternative to chemically selectable markers, such as kanamycin resistance. After transformation, red coloured calli, red shoots and red well-growing plants were scored. Red and green shoots were harvested from apple explants and examined for the presence of the MYB10 gene by PCR analysis. Red shoots of apple explants always contained the MYB10 gene but not all MYB10 containing shoots were red. Strawberry plants transformed with the MYB10 gene showed anthocyanin accumulation in leaves and roots. No visible accumulation of anthocyanin could be observed in potato plants grown in vitro, even the ones carrying the MYB10 gene. However, acid methanol extracts of potato shoots or roots carrying the MYB10 gene contained up to four times higher anthocyanin content than control plants. Therefore anthocyanin production as result of the apple MYB10 gene can be used as a selectable marker for apple, strawberry and potato transformation, replacing kanamycin resistance. PMID:21340526

  20. Using a semi-natural stream to produce young sturgeons for conservation stocking: Maintaining natural selection during spawning and rearing

    USGS Publications Warehouse

    Kynard, B.; Pugh, D.; Parker, T.; Kieffer, M.

    2011-01-01

    Young sturgeons used for conservation stocking are presently produced using the same methods used for commercial culture. To determine if young sturgeons could be produced without relaxing natural selection factors, we developed a semi-natural stream where we annually studied mating of wild shortnose sturgeon (Acipenser brevirostrum) observed movement of gametes released freely during spawning, and estimated the number of larvae produced by various densities of spawned eggs. The stream had a bottom area of 18.8m2, a rubble-gravel bottom, and a mean bottom current at 0.6 depth during spawning of 48cms-1 (range, 17-126cms-1). Wild adults successfully spawned in the stream each year for 7years (2002-2008). Some females and males were more successful during spawning than others, suggesting an unequal fitness during spawning among wild individuals, which is different than the controlled spawning fitness of individuals in hatcheries. Male and female gametes spawned naturally must connect quickly in the fast current or fail, a selection factor absent in hatcheries. The number of larvae produced was inversely related to spawned egg densitym-2 (R2=0.65) and the maximum number of larvae produced was 8000-16000 (425-851larvaem-2 of bottom). Artificial spawning streams have the potential to contribute to sturgeon restoration. ?? 2011 Blackwell Verlag, Berlin.

  1. From Ends to Causes (and Back Again) by Metaphor: The Paradox of Natural Selection

    NASA Astrophysics Data System (ADS)

    Blancke, Stefaan; Schellens, Tammy; Soetaert, Ronald; Van Keer, Hilde; Braeckman, Johan

    2014-04-01

    Natural selection is one of the most famous metaphors in the history of science. Charles Darwin used the metaphor and the underlying analogy to frame his ideas about evolution and its main driving mechanism into a full-fledged theory. Because the metaphor turned out to be such a powerful epistemic tool, Darwin naturally assumed that he could also employ it as an educational tool to inform his contemporaries about his findings. Moreover, by using the metaphor Darwin was able to bring his theory in accordance with both the dominant philosophy of science in his time and the respected tradition of natural theology. However, as he introduced his theory of evolution by natural selection in On the origin of species in 1859, the metaphor also turned out to have a serious downside. Because of its intentional overtones, his contemporaries systematically misunderstood his metaphor not as a natural mechanism causing evolution to occur but as an agent who works towards particular ends. The difference in success between natural selection as an epistemic tool and its failure as an educational tool is labelled as a paradox. We explain the paradox from a cognitive perspective and discuss the implications for teaching evolution.

  2. Imprints of Natural Selection Along Environmental Gradients in Phenology-Related Genes of Quercus petraea

    PubMed Central

    Alberto, Florian J.; Derory, Jérémy; Boury, Christophe; Frigerio, Jean-Marc; Zimmermann, Niklaus E.; Kremer, Antoine

    2013-01-01

    We explored single nucleotide polymorphism (SNP) variation in candidate genes for bud burst from Quercus petraea populations sampled along gradients of latitude and altitude in Western Europe. SNP diversity was monitored for 106 candidate genes, in 758 individuals from 32 natural populations. We investigated whether SNP variation reflected the clinal pattern of bud burst observed in common garden experiments. We used different methods to detect imprints of natural selection (FST outlier, clinal variation at allelic frequencies, association tests) and compared the results obtained for the two gradients. FST outlier SNPs were found in 15 genes, 5 of which were common to both gradients. The type of selection differed between the two gradients (directional or balancing) for 3 of these 5. Clinal variations were observed for six SNPs, and one cline was conserved across both gradients. Association tests between the phenotypic or breeding values of trees and SNP genotypes identified 14 significant associations, involving 12 genes. The results of outlier detection on the basis of population differentiation or clinal variation were not very consistent with the results of association tests. The discrepancies between these approaches may reflect the different hierarchical levels of selection considered (inter- and intrapopulation selection). Finally, we obtained evidence for convergent selection (similar for gradients) and clinal variation for a few genes, suggesting that comparisons between parallel gradients could be used to screen for major candidate genes responding to natural selection in trees. PMID:23934884

  3. Mercury uptake and phytotoxicity in terrestrial plants grown naturally in the Gumuskoy (Kutahya) mining area, Turkey.

    PubMed

    Sasmaz, Merve; Akgül, Bunyamin; Yıldırım, Derya; Sasmaz, Ahmet

    2016-01-01

    This study investigated mercury (Hg) uptake and transport from the soil to different plant parts by documenting the distribution and accumulation of Hg in the roots and shoots of 12 terrestrial plant species, all of which grow naturally in surface soils of the Gumuskoy Pb-Ag mining area. Plant samples and their associated soils were collected and analyzed for Hg content by ICP-MS. Mean Hg values in the soils, roots, and shoots of all plants were 6.914, 460, and 206 µg kg(-1), respectively and lower than 1. The mean enrichment factors for the roots (ECR) and shoots (ECS) of these plants were 0.06 and 0.09, respectively and lower than 1. These results show that the roots of the studied plants prevented Hg from reaching the aerial parts of the plants. The mean translocation factor (TLF) was 1.29 and higher than 1. The mean TLF values indicated that all 12 plant species had the ability to transfer Hg from the roots to the shoots but that transfer was more efficient in plants with higher ECR and ECS. Therefore, these plants could be useful for the biomonitoring of environmental pollution and for rehabilitating areas contaminated by Hg. PMID:26114359

  4. Computational genomic identification and functional reconstitution of plant natural product biosynthetic pathways.

    PubMed

    Medema, Marnix H; Osbourn, Anne

    2016-08-27

    Covering: 2003 to 2016The last decade has seen the first major discoveries regarding the genomic basis of plant natural product biosynthetic pathways. Four key computationally driven strategies have been developed to identify such pathways, which make use of physical clustering, co-expression, evolutionary co-occurrence and epigenomic co-regulation of the genes involved in producing a plant natural product. Here, we discuss how these approaches can be used for the discovery of plant biosynthetic pathways encoded by both chromosomally clustered and non-clustered genes. Additionally, we will discuss opportunities to prioritize plant gene clusters for experimental characterization, and end with a forward-looking perspective on how synthetic biology technologies will allow effective functional reconstitution of candidate pathways using a variety of genetic systems. PMID:27321668

  5. Strong selection on mandible and nest features in a carpenter bee that nests in two sympatric host plants

    PubMed Central

    Flores-Prado, Luis; Pinto, Carlos F; Rojas, Alejandra; Fontúrbel, Francisco E

    2014-01-01

    Host plants are used by herbivorous insects as feeding or nesting resources. In wood-boring insects, host plants features may impose selective forces leading to phenotypic differentiation on traits related to nest construction. Carpenter bees build their nests in dead stems or dry twigs of shrubs and trees; thus, mandibles are essential for the nesting process, and the nest is required for egg laying and offspring survival. We explored the shape and intensity of natural selection on phenotypic variation on three size measures of the bees (intertegular width, wing length, and mandible area) and two nest architecture measures (tunnel length and diameter) on bees using the native species Chusquea quila (Poaceae), and the alloctonous species Rubus ulmifolius (Rosaceae), in central Chile. Our results showed significant and positive linear selection gradients for tunnel length on both hosts, indicating that bees building long nests have more offspring. Bees with broader mandibles show greater fitness on C. quila but not on R. ulmifolius. Considering that C. quila represents a selective force on mandible area, we hypothesized a high adaptive value of this trait, resulting in higher fitness values when nesting on this host, despite its wood is denser and hence more difficult to be bored. PMID:24963379

  6. Strong selection on mandible and nest features in a carpenter bee that nests in two sympatric host plants.

    PubMed

    Flores-Prado, Luis; Pinto, Carlos F; Rojas, Alejandra; Fontúrbel, Francisco E

    2014-05-01

    Host plants are used by herbivorous insects as feeding or nesting resources. In wood-boring insects, host plants features may impose selective forces leading to phenotypic differentiation on traits related to nest construction. Carpenter bees build their nests in dead stems or dry twigs of shrubs and trees; thus, mandibles are essential for the nesting process, and the nest is required for egg laying and offspring survival. We explored the shape and intensity of natural selection on phenotypic variation on three size measures of the bees (intertegular width, wing length, and mandible area) and two nest architecture measures (tunnel length and diameter) on bees using the native species Chusquea quila (Poaceae), and the alloctonous species Rubus ulmifolius (Rosaceae), in central Chile. Our results showed significant and positive linear selection gradients for tunnel length on both hosts, indicating that bees building long nests have more offspring. Bees with broader mandibles show greater fitness on C. quila but not on R. ulmifolius. Considering that C. quila represents a selective force on mandible area, we hypothesized a high adaptive value of this trait, resulting in higher fitness values when nesting on this host, despite its wood is denser and hence more difficult to be bored. PMID:24963379

  7. Antioxidant responses in soybean and alfalfa plants grown in DDTs contaminated soils: Useful variables for selecting plants for soil phytoremediation?

    PubMed

    Mitton, Francesca M; Ribas Ferreira, Josencler L; Gonzalez, Mariana; Miglioranza, Karina S B; Monserrat, José M

    2016-06-01

    Phytoremediation is a low-cost alternative technology based on the use of plants to remove pollutants from the environment. Persistent organic pollutants such as DDTs with a long half-life in soils are attractive candidates for remediation. This study aimed to determine the potential of antioxidant response use in the evaluation of plants' tolerance for selecting species in phytoremediation purposes. Alfalfa and soybean plants were grown in DDT contaminated soils. After 60days, growth, protein content, antioxidant capacity, GST activity, concentration of proteic and non-proteic thiol groups, chlorophyll content and carotenoid content were measured in plant tissues. Results showed no effect on alfalfa or soybean photosynthetic pigments but different responses in the protein content, antioxidant capacity, GST activity and thiol groups on roots, stems and leaves, indicating that DDTs affected both species. Soybean showed higher susceptibility than alfalfa plants due to the lower antioxidant capacity and GST activity in leaves, in spite of having the lowest DDT accumulation. This study provides new insights into the role of oxidative stress as an important component of the plant's response to DDT exposure. PMID:27155479

  8. Natural or internal selection? The case of canalization in complex evolutionary systems.

    PubMed

    Riegler, Alexander

    2008-01-01

    Using biological examples and theoretical arguments, the case is presented for extending the notion of natural selection to include internal selection in order to account for the evolution of complex systems. It is suggested that we take into consideration internal factors that arise from the hierarchical dynamics of complex systems. In addition to environmental selection, it is argued, decisive constraints are created by the system itself. Canalization is shown to be an indispensable ingredient for evolutionary processes in both biological and artificial complex systems. In artificial life systems canalization is not only an instrument for controlling complexity, it also increases the speed and stability of evolutionary processes. PMID:18489255

  9. Population history and natural selection shape patterns of genetic variation in 132 genes.

    PubMed

    Akey, Joshua M; Eberle, Michael A; Rieder, Mark J; Carlson, Christopher S; Shriver, Mark D; Nickerson, Deborah A; Kruglyak, Leonid

    2004-10-01

    Identifying regions of the human genome that have been targets of natural selection will provide important insights into human evolutionary history and may facilitate the identification of complex disease genes. Although the signature that natural selection imparts on DNA sequence variation is difficult to disentangle from the effects of neutral processes such as population demographic history, selective and demographic forces can be distinguished by analyzing multiple loci dispersed throughout the genome. We studied the molecular evolution of 132 genes by comprehensively resequencing them in 24 African-Americans and 23 European-Americans. We developed a rigorous computational approach for taking into account multiple hypothesis tests and demographic history and found that while many apparent selective events can instead be explained by demography, there is also strong evidence for positive or balancing selection at eight genes in the European-American population, but none in the African-American population. Our results suggest that the migration of modern humans out of Africa into new environments was accompanied by genetic adaptations to emergent selective forces. In addition, a region containing four contiguous genes on Chromosome 7 showed striking evidence of a recent selective sweep in European-Americans. More generally, our results have important implications for mapping genes underlying complex human diseases. PMID:15361935

  10. Natural Products from Plant-associated Microorganisms: Distribution, Structural Diversity, Bioactivity, and Implications of Their Occurrence⊥

    PubMed Central

    Gunatilaka, A. A. Leslie

    2012-01-01

    A growing body of evidence suggests that plant-associated microorganisms, especially endophytic and rhizosphere bacteria and fungi, represent a huge and largely untapped resource of natural products with chemical structures that have been optimized by evolution for biological and ecological relevance. A diverse array of bioactive small molecule natural products has been encountered in these microorganisms. The structures of over 230 metabolites isolated and characterized from over 70 plant-associated microbial strains during the past four years are presented with information on their hosts, culture conditions, and biological activities. Some significant biological and ecological implications of their occurrence are also reviewed. PMID:16562864

  11. 40 CFR 60.5405 - What standards apply to sweetening units at onshore natural gas processing plants?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... units at onshore natural gas processing plants? 60.5405 Section 60.5405 Protection of Environment... SOURCES Standards of Performance for Crude Oil and Natural Gas Production, Transmission and Distribution § 60.5405 What standards apply to sweetening units at onshore natural gas processing plants? (a)...

  12. 40 CFR 60.5405 - What standards apply to sweetening units at onshore natural gas processing plants?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... units at onshore natural gas processing plants? 60.5405 Section 60.5405 Protection of Environment... SOURCES Standards of Performance for Crude Oil and Natural Gas Production, Transmission and Distribution § 60.5405 What standards apply to sweetening units at onshore natural gas processing plants? (a)...

  13. Evolving Better Cars: Teaching Evolution by Natural Selection with a Digital Inquiry Activity

    ERIC Educational Resources Information Center

    Royer, Anne M.; Schultheis, Elizabeth H.

    2014-01-01

    Evolutionary experiments are usually difficult to perform in the classroom because of the large sizes and long timescales of experiments testing evolutionary hypotheses. Computer applications give students a window to observe evolution in action, allowing them to gain comfort with the process of natural selection and facilitating inquiry…

  14. Human vs. Computer Diagnosis of Students' Natural Selection Knowledge: Testing the Efficacy of Text Analytic Software

    ERIC Educational Resources Information Center

    Nehm, Ross H.; Haertig, Hendrik

    2012-01-01

    Our study examines the efficacy of Computer Assisted Scoring (CAS) of open-response text relative to expert human scoring within the complex domain of evolutionary biology. Specifically, we explored whether CAS can diagnose the explanatory elements (or Key Concepts) that comprise undergraduate students' explanatory models of natural selection with…

  15. Instructional Design Consequences of an Analogy between Evolution by Natural Selection and Human Cognitive Architecture

    ERIC Educational Resources Information Center

    Sweller, John

    2004-01-01

    Evolution by natural selection may be characterized as a system in which a large store of genetic information will persist indefinitely while it remains coordinated with its environment but will continuously produce small random variations that are tested for environmental effectiveness. In any environment, effective variations will persist while…

  16. Aging is neither a failure nor an achievement of natural selection.

    PubMed

    Aledo, Juan Carlos; Blanco, José María

    2015-01-01

    In contraposition to the view of aging as a stochastic time-dependent accumulation of damage, phenoptotic theories of aging postulate that senescence may provide supra-individual advantages, and therefore it might have been promoted by natural selection. We reason that although programmed aging theories are subjectively appealing because they convey a cure for aging, they also raise a number of objections that need to be dealt with, before we may be entitled to contemplate aging as an adaptive function evolved through natural selection. As an alternative view, we present metabolism as an endless source of by-products and errors causing cellular damage. Although this damage accumulation event is a spontaneous entropy-driven process, its kinetics can be genetically and environmentally modulated, giving place to the wide range of lifespans we observe. Mild forms of damage may be accumulating during a long enough period of time to allow reproduction before the fatal failure happens. Hence, aging would be a stochastic process out of the reach of natural selection. However, those genetic pathways influencing the rate of aging and consequently determining longevity may be targets of natural selection and may contribute to shaping the optimal strategy according to the ecological context. In this sense, short- and long-lived organisms represent two extreme strategies that, in terms of biological fitness, can perform equally well, each within its own niche. PMID:26054343

  17. Student Conceptions of Natural Selection and Its Role in Evolution, Research Series No. l65.

    ERIC Educational Resources Information Center

    Bishop, Beth A.; Anderson, Charles W.

    Pretests and posttests on the topic of evolution through natural selection were administered to students in a college nonmajors' biology course. Analysis of test responses revealed that most students understood evolution as a process in which species respond to environmental conditions by changing gradually over time. Student thinking differed…

  18. Darwin's Arguments in Favour of Natural Selection and against Special Creationism

    ERIC Educational Resources Information Center

    Nola, Robert

    2013-01-01

    In many places in "The Origin of Species", Darwin compares his own theory of Natural Selection favourably with Special Creationism which comes off as a bad second best. He does this using some version of the argument form known as "Inference to the Best Explanation". The first part of this paper is methodological. It considers Whewell's notion of…

  19. Studying the Genetics of Behavior and Evolution by Adaptation and Natural Selection.

    ERIC Educational Resources Information Center

    Silverman, Jules

    1998-01-01

    Provides an exercise designed to give students an appreciation for the genetic basis of behavior. Employs the phenomenon of glucose aversion as an example of evolution by mutation and accelerated natural selection, thereby revealing one of the ways in which organisms adapt to human interference. (DDR)

  20. Using the FAR Guide to Teach Simulations: An Example with Natural Selection

    ERIC Educational Resources Information Center

    Sickel, Aaron J.; Friedrichsen, Patricia J.

    2012-01-01

    Engaging students in a predator-prey simulation to teach natural selection is a common activity in secondary biology classrooms. The purpose of this article is to demonstrate how the authors have changed their approach to teaching this activity from a laboratory investigation to a class-constructed simulation. Specifically, the authors drew upon a…

  1. Reasoning about Natural Selection: Diagnosing Contextual Competency Using the ACORNS Instrument

    ERIC Educational Resources Information Center

    Nehm, Ross H.; Beggrow, Elizabeth P.; Opfer, John E.; Ha, Minsu

    2012-01-01

    Studies of students' thinking about natural selection have revealed that the scenarios in which students reason evoke different types, magnitudes, and arrangements of knowledge elements and misconceptions. Diagnostic tests are needed that probe students' thinking across a representative array of evolutionary contexts. The ACORNS is a diagnostic…

  2. Developing Conceptual Understanding of Natural Selection: The Role of Interest, Efficacy, and Basic Prior Knowledge

    ERIC Educational Resources Information Center

    Linnenbrink-Garcia, Lisa; Pugh, Kevin J.; Koskey, Kristin L. K.; Stewart, Victoria C.

    2012-01-01

    Changes in high school students' (n = 94) conceptions of natural selection were examined as a function of motivational beliefs (individual interest, academic self-efficacy), basic prior knowledge, and gender across three assessments (pre, post, follow-up). Results from variable-centered analyses suggested that these variables had relatively little…

  3. The Future of Natural Selection Knowledge Measurement: A Reply to Anderson et al. (2010)

    ERIC Educational Resources Information Center

    Nehm, Ross H.; Schonfeld, Irvin Sam

    2010-01-01

    The development of rich, reliable, and robust measures of the composition, structure, and stability of student thinking about core scientific ideas (such as natural selection) remains a complex challenge facing science educators. In their recent article (Nehm & Schonfeld 2008), the authors explored the strengths, weaknesses, and insights provided…

  4. The Power of Natural Selection: A Guided Investigation of Three Case Studies

    ERIC Educational Resources Information Center

    Beachly, William

    2010-01-01

    I describe a quantitative approach to three case studies in evolution that can be used to challenge college freshmen to explore the power of natural selection and ask questions that foster a deeper understanding of its operation and relevance. Hemochromatosis, the peppered moth, and hominid cranial capacity are investigated with a common algebraic…

  5. Unweaving Misconceptions: Guided Learning, Simulations, and Misconceptions in Learning Principles of Natural Selection

    ERIC Educational Resources Information Center

    Weeks, Brian E.

    2013-01-01

    College students often come to the study of evolutionary biology with many misconceptions of how the processes of natural selection and speciation occur. How to relinquish these misconceptions with learners is a question that many educators face in introductory biology courses. Constructivism as a theoretical framework has become an accepted and…

  6. Influences of Teleological and Lamarckian Thinking on Student Understanding of Natural Selection

    ERIC Educational Resources Information Center

    Stover, Shawn K.; Mabry, Michelle L.

    2007-01-01

    Previous research has demonstrated creationist, Lamarckian, and teleological reasoning in high school and college students. These lines of thinking conflict with the Darwinian notion of natural selection, which serves as the primary catalyst for biological evolution. The current study assessed evolutionary conceptions in non-science majors,…

  7. Synthetic mimicking of plant oils and comparison with naturally grown products in polyurethane synthesis.

    PubMed

    Coles, Stuart R; Barker, Guy; Clark, Andrew J; Kirwan, Kerry; Jacobs, Daniel; Makenji, Kylash; Pink, David

    2008-06-11

    The use of plant oils as industrial feedstocks can often be hampered by their lack of optimization towards a particular process, as well as their development being risky; growing suitable volumes of crops to test can take up to five years. To circumvent this, we aimed to discover a method that would mimic plant oil profiles in the laboratory, and show that they exhibited similar properties to the naturally grown plant oils in a given process. Using the synthesis of polyurethanes as an example, we have synthesized six different polymers and demonstrated that plant oils will produce polymers with similar physical properties to those oils mimicked in the laboratory. The use of this mimicking process can be extended to other types of polymers to obtain a method for predicting the properties of a given material based on the plant oil composition of a crop before it is grown in bulk. PMID:18322912

  8. Experience-Dependent Specialization of Receptive Field Surround for Selective Coding of Natural Scenes

    PubMed Central

    Pecka, Michael; Han, Yunyun; Sader, Elie; Mrsic-Flogel, Thomas D.

    2014-01-01

    Summary At eye opening, neurons in primary visual cortex (V1) are selective for stimulus features, but circuits continue to refine in an experience-dependent manner for some weeks thereafter. How these changes contribute to the coding of visual features embedded in complex natural scenes remains unknown. Here we show that normal visual experience after eye opening is required for V1 neurons to develop a sensitivity for the statistical structure of natural stimuli extending beyond the boundaries of their receptive fields (RFs), which leads to improvements in coding efficiency for full-field natural scenes (increased selectivity and information rate). These improvements are mediated by an experience-dependent increase in the effectiveness of natural surround stimuli to hyperpolarize the membrane potential specifically during RF-stimulus epochs triggering action potentials. We suggest that neural circuits underlying surround modulation are shaped by the statistical structure of visual input, which leads to more selective coding of features in natural scenes. PMID:25263755

  9. Examining beginning biology teachers' knowledge, beliefs, and practice for teaching natural selection

    NASA Astrophysics Data System (ADS)

    Sickel, Aaron J.

    The teacher is the most important school-based factor in student learning. Thus, in order to improve student learning, we must examine how teachers learn to teach. My overarching research agenda centers upon K-16 science teacher learning and development. Within this agenda, I conduct studies focused on two strands of research: 1) How teachers learn to teach science using constructivist and inquiry-oriented teaching strategies; and 2) How teachers learn to teach biological evolution. This dissertation merges the two strands together, and consists of four related manuscripts that address how beginning biology teachers learn to teach natural selection using constructivist and inquiry-oriented teaching strategies. In the first manuscript, I reviewed the evolution education literature focused on K-12 teachers’ knowledge, beliefs, and practice for teaching evolution. Based upon findings across the studies, I articulated five goals for preparing teachers to teach evolution. The second and third manuscripts are longitudinal empirical studies focused on three beginning biology teachers learning to teach natural selection using the 5E instructional model and interactive classroom simulations. The fourth manuscript is a practitioner article that explains how to teach natural selection simulations using a constructivist, analogy-based teaching strategy. Findings that cut across the four manuscripts are organized into the following themes: (A) The participants developed some common types of knowledge for teaching natural selection, yet also developed in unique ways. All participants developed knowledge of the horizontal curriculum. Yet, participants also developed different types of knowledge. For example, participants who had taken an evolution course developed more integrated pedagogical content knowledge for teaching the core concepts of natural selection. The participant who integrated discipline-level knowledge for teaching science through inquiry with topic

  10. Soil, plant, and terrain effects on natural perchlorate distribution in a desert landscape

    USGS Publications Warehouse

    Andraski, Brian J.; Jackson, W.A.; Welborn, Toby L.; Böhlke, John Karl; Sevanthi, Ritesh; Stonestrom, David A.

    2014-01-01

    Perchlorate (ClO4−) is a contaminant that occurs naturally throughout the world, but little is known about its distribution and interactions in terrestrial ecosystems. The objectives of this Amargosa Desert, Nevada study were to determine (i) the local-scale distribution of shallow-soil (0–30 cm) ClO4− with respect to shrub proximity (far and near) in three geomorphic settings (shoulder slope, footslope, and valley floor); (ii) the importance of soil, plant, and terrain variables on the hillslope-distribution of shallow-soil and creosote bush [Larrea tridentata (Sessé & Moc. ex DC.) Coville] ClO4−; and (iii) atmospheric (wet plus dry, including dust) deposition of ClO4− in relation to soil and plant reservoirs and cycling. Soil ClO4− ranged from 0.3 to 5.0 μg kg−1. Within settings, valley floor ClO4− was 17× less near shrubs due in part to enhanced leaching, whereas shoulder and footslope values were ∼2× greater near shrubs. Hillslope regression models (soil, R2 = 0.42; leaf, R2 = 0.74) identified topographic and soil effects on ClO4− deposition, transport, and cycling. Selective plant uptake, bioaccumulation, and soil enrichment were evidenced by leaf ClO4− concentrations and Cl−/ClO4− molar ratios that were ∼8000× greater and 40× less, respectively, than soil values. Atmospheric deposition ClO4− flux was 343 mg ha−1 yr−1, ∼10× that for published southwestern wet-deposition fluxes. Creosote bush canopy ClO4− (1310 mg ha−1) was identified as a previously unrecognized but important and active reservoir. Nitrate δ18O analyses of atmospheric deposition and soil supported the leaf-cycled–ClO4− input hypothesis. This study provides basic data on ClO4− distribution and cycling that are pertinent to the assessment of environmental impacts in desert ecosystems and broadly transferable to anthropogenically contaminated systems.

  11. Plant aquaporin selectivity: where transport assays, computer simulations and physiology meet.

    PubMed

    Ludewig, Uwe; Dynowski, Marek

    2009-10-01

    Plants contain a large number of aquaporins with different selectivity. These channels generally conduct water, but some additionally conduct NH(3), CO(2) and/or H(2)O(2). The experimental evidence and molecular basis for the transport of a given solute, the validation with molecular dynamics simulations and the physiological impact of the selectivity are reviewed here. The aromatic/arginine (ar/R) constriction is most important for solute selection, but the exact pore requirements for efficient conduction of small solutes remain difficult to predict. Yeast growth assays are valuable for screening substrate selectivity and are explicitly shown for hydrogen peroxide and methylamine, a transport analog of ammonia. Independent assays need to address the relevance of different substrates for each channel in its physiological context. This is emphasized by the fact that several plant NIP channels, which conduct several solutes, are specifically involved in the transport of metalloids, such as silicic acid, arsenite, or boric acid in planta. PMID:19565186

  12. Natural selection influences AFLP intraspecific genetic variability and introgression patterns in Atlantic eels.

    PubMed

    Gagnaire, P A; Albert, V; Jónsson, B; Bernatchez, L

    2009-04-01

    Investigating patterns of genetic variation in hybridizing species provides an opportunity to understand the impact of natural selection on intraspecific genetic variability and interspecific gene exchange. The Atlantic eels Anguilla rostrata and A. anguilla each occupy a large heterogeneous habitat upon which natural selection could differentially shape genetic variation. They also produce viable hybrids only found in Iceland. However, the possible footprint of natural selection on patterns of genetic variation within species and introgressive hybridization in Icelandic eels has never been assessed. We revisited amplified fragment length polymorphism data collected previously using population genomics and admixture analyses to test if (i) genetic variation could be influenced by non-neutral mechanisms at both the intra- and interspecific levels, and if (ii) selection could shape the spatio-temporal distribution of Icelandic hybrids. We first found candidate loci for directional selection within both species. Spatial distributions of allelic frequencies displayed by some of these loci were possibly related with the geographical patterns of life-history traits in A. rostrata, and could have been shaped by natural selection associated with an environmental gradient along European coasts in A. anguilla. Second, we identified outlier loci at the interspecific level. Non-neutral introgression was strongly suggested for some of these loci. We detected a locus at which typical A. rostrata allele hardly crossed the species genetic barrier, whereas three other loci showed accelerated patterns of introgression into A. anguilla in Iceland. Moreover, the level of introgression at these three loci increased from the glass eel to the yellow eel stage, supporting the hypothesis that differential survival of admixed genotypes partly explains the spatio-temporal pattern of hybrid abundance previously documented in Iceland. PMID:19302349

  13. Phenolic content of some selected Lamiaceous Egyptian medicinal plants: antioxidant potential and ecological friend mosquito-larvicldal.

    PubMed

    Abdel-Hady, Nevein M; El-Hela, Atef A; Morsy, Tosson A

    2014-04-01

    Phenol compounds are naturally occurring biologically active compounds existing in all plants had received major medical concern so development in research focused on their extraction, identification and quantification have occurred over the last 25 years; they constitute an important source of antioxidants and were used to help human body to reduce oxidative damage. Mosquitos-borne diseases constitute one of the major health problems worldwide. Control strategies involving pinpointing natural ecological friend, cheap and safe mosquitocides, mainly larvicides to stop their life cycle. Quantitative estimation of total phenol, flavonoids, phenylethanoid and iridoid contents of sixteen selected Lamiaceous Egyptian plants for screening of their antioxidant and mosquito larvicidal effects was carried out. The results showed that the most suitable medicinal plants used as antioxidants were Lavendula dentata L., Thymus capitatus L. and Thymus bovei Benth., which contain adequate mixture of total phenol, flavonoid and phenylethanoid contents, with distinct larvicidal effect in a descending order was T. capitatus L., T. bovei Benth. and L. dentata L. by their adequate mixture of total phenol, flavonoid, iridoid and phenylethanoid glycoside content. PMID:24961008

  14. In vitro antiplasmodial, antileishmanial and antitrypanosomal activities of selected medicinal plants used in the traditional Arabian Peninsular region

    PubMed Central

    2012-01-01

    Background Worldwide particularly in developing countries, a large proportion of the population is at risk for tropical parasitic diseases. Several medicinal plants are still used traditionally against protozoal infections in Yemen and Saudi Arabia. Thus the present study investigated the in vitro antiprotozoal activity of twenty-five plants collected from the Arabian Peninsula. Methods Plant materials were extracted with methanol and screened in vitro against erythrocytic schizonts of Plasmodium falciparum, intracellular amastigotes of Leishmania infantum and Trypanosoma cruzi and free trypomastigotes of T. brucei. Cytotoxic activity was determined against MRC-5 cells to assess selectivity. The criterion for activity was an IC50 < 10 μg/ml (<5 μg/ml for T. brucei) and selectivity index of >4. Results Antiplasmodial activity was found in the extracts of Chrozophora oblongifolia, Ficus ingens, Lavandula dentata and Plectranthus barbatus. Amastigotes of T. cruzi were affected by Grewia erythraea, L. dentata, Tagetes minuta and Vernonia leopoldii. Activity against T. brucei was obtained in G. erythraea, L. dentata, P. barbatus and T. minuta. No relevant activity was found against L. infantum. High levels of cytotoxicity (MRC-5 IC50 < 10 μg/ml) and hence non-specific activities were noted in Cupressus sempervirens, Kanahia laniflora and Kniphofia sumarae. Conclusion The results endorse that medicinal plants can be promising sources of natural products with antiprotozoal activity potential. The results support to some extent the traditional uses of some plants for the treatment of parasitic protozoal diseases. PMID:22520595

  15. The Influence of Selected Management Practices on Soybean Soil-Plant Relationships.

    NASA Astrophysics Data System (ADS)

    Brumback, Thomas Benton, Jr.

    Research was conducted in Columbia, Missouri, during the 1976 to 1978 growing seasons to determine the impact of selected management practices on the soil, plant, and water relationships of soybeans {Glycine max (L.) merr.}. Four different management practices for growing 'Williams' soybeans were established in a corn-soybean rotation experiment on a Mexico silt loam soil. A standard cultural practice (conventional tillage, early-May planting date, preemergence and postemergence application of a herbicide) was designated as a control. By changing the planting date, tillage method, or herbicide application, three other treatments were provided: June planting (as soon as possible after June 1), weedy planting (no postemergence herbicide), and no-tillage. No differences in the diurnal trends of xylem pressure potential, leaf conductance, and leaf temperatures were found among treatments. Mean plant water stress over the three years was greatest for the weedy treatment and least for the June planting. Mean xylem pressure potential was -1.30, -1.19, -1.14, and -1.05 MPa for the weedy, May planting, no-tillage, and June plantings, respectively. A similar treatment ranking was found when stress was based on leaf conductance and leaf temperature (0.16, 0.18, 0.21, 0.21 cm sec('-1) leaf conductance and 32.8, 32.5, 32.3, 32.2(DEGREES)C leaf temperature for the weedy, May planting, no-tillage, and June plantings, respectively). Differences in plant growth and seed yields among management practices were attributed to plant water stress. Mean yields for the three-year study were 1590, 1530, 1520, and 970 kg ha('-1) for the June planting, May planting, weedy, and no-tillage treatments, respectively. Despite their greater growth and favorable water relations, the no-tillage soybeans had the lowest yields of all treatments because of weed competition and sparse stands. Because of greater soil moisture reserves during pod-fill, June plantings had lower stress and slightly higher

  16. Discovery and resupply of pharmacologically active plant-derived natural products: A review

    PubMed Central

    Linder, Thomas; Wawrosch, Christoph; Uhrin, Pavel; Temml, Veronika; Wang, Limei; Schwaiger, Stefan; Heiss, Elke H.; Rollinger, Judith M.; Schuster, Daniela; Breuss, Johannes M.; Bochkov, Valery; Mihovilovic, Marko D.; Kopp, Brigitte; Bauer, Rudolf; Dirsch, Verena M.; Stuppner, Hermann

    2016-01-01

    Medicinal plants have historically proven their value as a source of molecules with therapeutic potential, and nowadays still represent an important pool for the identification of novel drug leads. In the past decades, pharmaceutical industry focused mainly on libraries of synthetic compounds as drug discovery source. They are comparably easy to produce and resupply, and demonstrate good compatibility with established high throughput screening (HTS) platforms. However, at the same time there has been a declining trend in the number of new drugs reaching the market, raising renewed scientific interest in drug discovery from natural sources, despite of its known challenges. In this survey, a brief outline of historical development is provided together with a comprehensive overview of used approaches and recent developments relevant to plant-derived natural product drug discovery. Associated challenges and major strengths of natural product-based drug discovery are critically discussed. A snapshot of the advanced plant-derived natural products that are currently in actively recruiting clinical trials is also presented. Importantly, the transition of a natural compound from a “screening hit” through a “drug lead” to a “marketed drug” is associated with increasingly challenging demands for compound amount, which often cannot be met by re-isolation from the respective plant sources. In this regard, existing alternatives for resupply are also discussed, including different biotechnology approaches and total organic synthesis. While the intrinsic complexity of natural product-based drug discovery necessitates highly integrated interdisciplinary approaches, the reviewed scientific developments, recent technological advances, and research trends clearly indicate that natural products will be among the most important sources of new drugs also in the future. PMID:26281720

  17. Discovery and resupply of pharmacologically active plant-derived natural products: A review.

    PubMed

    Atanasov, Atanas G; Waltenberger, Birgit; Pferschy-Wenzig, Eva-Maria; Linder, Thomas; Wawrosch, Christoph; Uhrin, Pavel; Temml, Veronika; Wang, Limei; Schwaiger, Stefan; Heiss, Elke H; Rollinger, Judith M; Schuster, Daniela; Breuss, Johannes M; Bochkov, Valery; Mihovilovic, Marko D; Kopp, Brigitte; Bauer, Rudolf; Dirsch, Verena M; Stuppner, Hermann

    2015-12-01

    Medicinal plants have historically proven their value as a source of molecules with therapeutic potential, and nowadays still represent an important pool for the identification of novel drug leads. In the past decades, pharmaceutical industry focused mainly on libraries of synthetic compounds as drug discovery source. They are comparably easy to produce and resupply, and demonstrate good compatibility with established high throughput screening (HTS) platforms. However, at the same time there has been a declining trend in the number of new drugs reaching the market, raising renewed scientific interest in drug discovery from natural sources, despite of its known challenges. In this survey, a brief outline of historical development is provided together with a comprehensive overview of used approaches and recent developments relevant to plant-derived natural product drug discovery. Associated challenges and major strengths of natural product-based drug discovery are critically discussed. A snapshot of the advanced plant-derived natural products that are currently in actively recruiting clinical trials is also presented. Importantly, the transition of a natural compound from a "screening hit" through a "drug lead" to a "marketed drug" is associated with increasingly challenging demands for compound amount, which often cannot be met by re-isolation from the respective plant sources. In this regard, existing alternatives for resupply are also discussed, including different biotechnology approaches and total organic synthesis. While the intrinsic complexity of natural product-based drug discovery necessitates highly integrated interdisciplinary approaches, the reviewed scientific developments, recent technological advances, and research trends clearly indicate that natural products will be among the most important sources of new drugs also in the future. PMID:26281720

  18. What are plants doing and when? Using plant phenology to facilitate sustainable natural resources management

    USGS Publications Warehouse

    Chong, Geneva W.; Allen, Leslie A.

    2012-01-01

    Climate change models for the northern Rocky Mountains predict changes in temperature and water availability that in turn will alter vegetation. Changes include timing of plant life-history events, or phenology, such as green-up, flowering and senescence, and shifts in species composition. Moreover, climate changes may favor different species, such as nonnative, annual grasses over native species. Changes in vegetation could make forage for ungulates, sage-grouse, and livestock available earlier in the growing season, but shifts in species composition and phenology may also result in earlier senescence (die-off or dormancy) and reduced overall forage production.

  19. An orchid bee naturalizes in Florida; implications for orchids and other plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An orchid bee, Euglossa viridissima, from Mexico and Central America was detected in southern Florida in 2003 and now has become locally abundant. Orchid bees are important pollinators of diverse plants in their native tropical America which suggests that the naturalized orchid bee could become an i...

  20. Rearing optimization of two races of the Fall armyworm Spodoptera frugiperda feeding natural host plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two ecological races of the Fall armyworm Spodoptera frugiperda were raised under laboratory conditions feeding on natural host plants (corn and bermuda grass). Three rearing containers were used: a plastic container and a vertical cylinder to test fitness when feeding gregariously, and individual ...

  1. Relationship between humanity and plant natural resources – in the context of food and agriculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agriculture, the domestication, culture, and management of plants and animals, has led to profound social changes in human evolution and development; it can be considered as the basis for civilization. Roughly 12,000 years ago agriculture appeared independently in several parts of the world. A natur...

  2. Selective cytotoxicity of Pancratistatin-related natural Amaryllidaceae alkaloids: evaluation of the activity of two new compounds

    PubMed Central

    Griffin, Carly; Sharda, Natasha; Sood, Divya; Nair, Jerald; McNulty, James; Pandey, Siyaram

    2007-01-01

    Background Pancratistatin (PST), a compound extracted from an Amaryllidaceae (AMD) family plant, has been shown to specifically induce apoptosis in cancer cells with no/minimal toxic effect on normal cells. A systematic synthetic approach has indicated that the minimum cytotoxic pharmacophore comprises the trans-fused b/c-ring system containing the 2, 3, 4-triol unit in the C-ring. To further explore the structure-activity relationship of this group of compounds we have investigated the anti-cancer efficacy and specificity of two PST-related natural compounds, AMD4 and AMD5. Both of these compounds lack the polyhydroxylated lycorane element of PST instead having a methoxy-substuituted crinane skeleton. Results Our results indicate that AMD5 has efficacy and selectivity similar to PST, albeit at a 10-fold increased concentration. Interestingly AMD4 lacks apoptotic activity. Conclusion Our results indicate that the phenanthridone skeleton in natural Amaryllidaceae alkaloids may be a significant common element for selectivity against cancer cells; furthermore, the configuration of the methoxy-side groups is responsible for higher binding affinity to the target protein/s thus making for a more efficient anti-cancer agent. PMID:17550595

  3. Detecting the Genetic Signature of Natural Selection in Human Populations: Models, Methods, and Data

    PubMed Central

    Hancock, Angela M.; Rienzo, Anna Di

    2010-01-01

    Patterns of DNA sequence variation in the genome contain a record of past selective events. The ability to collect increasingly large data sets of polymorphisms has allowed investigators to perform hypothesis-driven studies of candidate genes as well as genome-wide scans for signatures of adaptations. This genetic approach to the study of natural selection has identified many signals consistent with predictions from anthropological studies. Selective pressures related to variation in climate, diet, and pathogen exposure have left strong marks on patterns of human variation. Additional signals of adaptations are observed in genes involved in chemosensory perception and reproduction. Several ongoing projects aim to sequence the complete genome of 1000 individuals from different human populations. These large-scale projects will provide data for more complete genome scans of selection, but more focused studies aimed at testing specific hypotheses will continue to hold an important place in elucidating the history of adaptations in humans. PMID:20622977

  4. Herbivore-induced plant volatiles mediate host selection by a root herbivore.

    PubMed

    Robert, Christelle A M; Erb, Matthias; Duployer, Marianne; Zwahlen, Claudia; Doyen, Gwladys R; Turlings, Ted C J

    2012-06-01

    In response to herbivore attack, plants mobilize chemical defenses and release distinct bouquets of volatiles. Aboveground herbivores are known to use changes in leaf volatile patterns to make foraging decisions, but it remains unclear whether belowground herbivores also use volatiles to select suitable host plants. We therefore investigated how above- and belowground infestation affects the performance of the root feeder Diabrotica virgifera virgifera, and whether the larvae of this specialized beetle are able to use volatile cues to assess from a distance whether a potential host plant is already under herbivore attack. Diabrotica virgifera larvae showed stronger growth on roots previously attacked by conspecific larvae, but performed more poorly on roots of plants whose leaves had been attacked by larvae of the moth Spodoptera littoralis. Fittingly, D. virgifera larvae were attracted to plants that were infested with conspecifics, whereas they avoided plants that were attacked by S. littoralis. We identified (E)-β-caryophyllene, which is induced by D. virgifera, and ethylene, which is suppressed by S. littoralis, as two signals used by D. virgifera larvae to locate plants that are most suitable for their development. Our study demonstrates that soil-dwelling insects can use herbivore-induced changes in root volatile emissions to identify suitable host plants. PMID:22486361

  5. The use of ECAS in plant protection: a green and efficient antimicrobial approach that primes selected defense genes.

    PubMed

    Zarattini, Marco; De Bastiani, Morena; Bernacchia, Giovanni; Ferro, Sergio; De Battisti, Achille

    2015-11-01

    The use of highly polluting chemicals for plant and crop protection is one of the components of the negative environmental impact of agricultural activities. In the present paper, an environmentally friendly alternative to pesticide application has been studied, based on the so-called electrochemically activated solutions (ECAS). Experiments have been carried out, by applying ECAS having different contents of active ingredients, on tobacco plants at a laboratory scale and on apple trees at fruit garden scale. The results, accumulated during a couple of years, have shown that properly selected dilute solutions of chlorides, once activated by an electrochemical treatment, exhibit a very effective protecting action of plants, irrespective of their nature. Extension of the research has shown that the observed effect is the result of two distinct factors: the expected anti-microbial action of the electrochemically synthesized oxidants, and an unexpected priming of immune plant defenses, which is clearly due to the treatment with ECAS. Interestingly, the repetition of ECAS application triggers an even stronger activation of defense genes. No oxidative damages, due to the use of the activated solutions, could be detected. PMID:26350548

  6. Selective transport systems mediate sequestration of plant glucosides in leaf beetles: A molecular basis for adaptation and evolution

    PubMed Central

    Kuhn, Jürgen; Pettersson, Eva M.; Feld, Birte K.; Burse, Antje; Termonia, Arnaud; Pasteels, Jacques M.; Boland, Wilhelm

    2004-01-01

    Chrysomeline larvae respond to disturbance and attack by everting dorsal glandular reservoirs, which release defensive secretions. The ancestral defense is based on the de novo synthesis of monoterpene iridoids. The catabolization of the host-plant O-glucoside salicin into salicylaldehyde is a character state that evolved later in two distinct lineages, which specialized on Salicaceae. By using two species producing monoterpenes (Hydrothassa marginella and Phratora laticollis) and two sequestering species (Chrysomela populi and Phratora vitellinae), we studied the molecular basis of sequestration by feeding the larvae structurally different thioglucosides resembling natural O-glucosides. Their accumulation in the defensive systems demonstrated that the larvae possess transport systems, which are evolutionarily adapted to the glycosides of their host plants. Minor structural modifications in the aglycon result in drastically reduced transport rates of the test compounds. Moreover, the ancestral iridoid-producing leaf beetles already possess a fully functional import system for an early precursor of the iridoid defenses. Our data confirm an evolutionary scenario in which, after a host-plant change, the transport system of the leaf beetles may play a pivotal role in the adaptation on new hosts by selecting plant-derived glucosides that can be channeled to the defensive system. PMID:15365181

  7. [Selective enrichment of Pseudomonas spp. in the rhizoplane of different plant species].

    PubMed

    Marrero, Mariana A; Agaras, Betina; Wall, Luis G; Valverde, Claudio

    2015-01-01

    In contrast to rhizobia-legume symbiosis, the specificity for root colonization by pseudomonads seems to be less strict. However, several studies about bacterial diversity in the rhizosphere highlight the influence of plant species on the selective enrichment of certain microorganisms from the bulk soil community. In order to evaluate the effect that different crops have on the structure of pseudomonad community on the root surface, we performed plant trap experiments, using surface-disinfected maize, wheat or soybean seeds that were sown in pots containing the same pristine soil as substrate. Rhizoplane suspensions were plated on a selective medium for Pseudomonas, and pooled colonies served as DNA source to carry out PCR-RFLP community structure analysis of the pseudomonads-specific marker genes oprF and gacA. PCR-RFLP profiles were grouped by plant species, and were distinguished from those of bulk soil samples. Partial sequencing of 16S rDNA genes of some representative colonies of Pseudomonas confirmed the selective enrichment of distinctive genotypes in the rhizoplane of each plant species. These results support the idea that the root systems of agricultural crops such as soybean, maize and wheat, select differential sets of pseudomonads from the native microbial repertoire inhabiting the bulk soil. PMID:26054776

  8. SELECTING AND EVALUATING NATIVE PLANTS FOR REGION-SPECIFIC PHYTOTOXICITY TESTING

    EPA Science Inventory

    In this study, we evaluated methodology to determine risks to terrestrial native plant species from potential herbicide drift, focusing on 1) selection of native species for testing, 2) growth of these species, and 3) variability in herbicide response among native species and com...

  9. Evaluation of Select USDA Watermelon Plant Introductions (PI) for Tolerance to Watermelon Vine Decline, 2006

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Watermelon vine decline (WVD) caused by squash vein yellowing virus (SqVYV) is a new and emerging disease in southwest and west central Florida. Watermelon plant introductions (PI) selected on the basis of a greenhouse screening against SqVYV were evaluated for tolerance to watermelon vine decline ...

  10. Using Reading Grade Level to Assess Readability of Selected Plant and Soil Science Textbooks.

    ERIC Educational Resources Information Center

    Graveel, John G.; Fribourg, Henry A.

    1987-01-01

    Reported is a study designed to determine whether reading grade level (RGL) assessment techniques used for elementary and secondary education textbooks would discriminate among plant and soil science textbooks. The study was to select the RGL indices suited to quantify the readability of these sources, and to identify the factors affecting…

  11. Plant breeding with genomic selection: potential gain per unit time and cost

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Advancements in genotyping are rapidly decreasing marker costs and increasing genome coverage. This is facilitating the use of marker-assisted selection (MAS) in plant breeding. Commonly employed MAS strategies, however, are not well suited for complex traits, requiring extra time for field-based ph...

  12. Plant Size as Determinant of Species Richness of Herbivores, Natural Enemies and Pollinators across 21 Brassicaceae Species

    PubMed Central

    Schlinkert, Hella; Westphal, Catrin; Clough, Yann; László, Zoltán; Ludwig, Martin; Tscharntke, Teja

    2015-01-01

    Large plants are often more conspicuous and more attractive for associated animals than small plants, e.g. due to their wider range of resources. Therefore, plant size can positively affect species richness of associated animals, as shown for single groups of herbivores, but studies usually consider intraspecific size differences of plants in unstandardised environments. As comprehensive tests of interspecific plant size differences under standardised conditions are missing so far, we investigated effects of plant size on species richness of all associated arthropods using a common garden experiment with 21 Brassicaceae species covering a broad interspecific plant size gradient from 10 to 130 cm height. We recorded plant associated ecto- and endophagous herbivores, their natural enemies and pollinators on and in each aboveground plant organ, i.e. flowers, fruits, leaves and stems. Plant size (measured as height from the ground), the number of different plant organ entities and their biomass were assessed. Increasing plant size led to increased species richness of associated herbivores, natural enemies and pollinating insects. This pattern was found for ectophagous and endophagous herbivores, their natural enemies, as well as for herbivores associated with leaves and fruits and their natural enemies, independently of the additional positive effects of resource availability (i.e. organ biomass or number of entities and, regarding natural enemies, herbivore species richness). We found a lower R2 for pollinators compared to herbivores and natural enemies, probably caused by the high importance of flower characteristics for pollinator species richness besides plant size. Overall, the increase in plant height from 10 to 130 cm led to a 2.7-fold increase in predicted total arthropod species richness. In conclusion, plant size is a comprehensive driver of species richness of the plant associated arthropods, including pollinators, herbivores and their natural enemies

  13. Trait differences between naturalized and invasive plant species independent of residence time and phylogeny.

    PubMed

    Gallagher, R V; Randall, R P; Leishman, M R

    2015-04-01

    The ability to predict which alien plants will transition from naturalized to invasive prior to their introduction to novel regions is a key goal for conservation and has the potential to increase the efficacy of weed risk assessment (WRA). However, multiple factors contribute to plant invasion success (e.g., functional traits, range characteristics, residence time, phylogeny), and they all must be taken into account simultaneously in order to identify meaningful correlates of invasion success. We compiled 146 pairs of phylogenetically paired (congeneric) naturalized and invasive plant species in Australia with similar minimum residence times (i.e., time since introduction in years). These pairs were used to test for differences in 5 functional traits (flowering duration, leaf size, maximum height, specific leaf area [SLA], seed mass) and 3 characteristics of species' native ranges (biome occupancy, mean annual temperature, and rainfall breadth) between naturalized and invasive species. Invasive species, on average, had larger SLA, longer flowering periods, and were taller than their congeneric naturalized relatives. Invaders also exhibited greater tolerance for different environmental conditions in the native range, where they occupied more biomes and a wider breadth of rainfall and temperature conditions than naturalized congeners. However, neither seed mass nor leaf size differed between pairs of naturalized and invasive species. A key finding was the role of SLA in distinguishing between naturalized and invasive pairs. Species with high SLA values were typically associated with faster growth rates, more rapid turnover of leaf material, and shorter lifespans than those species with low SLA. This suite of characteristics may contribute to the ability of a species to transition from naturalized to invasive across a wide range of environmental contexts and disturbance regimes. Our findings will help in the refinement of WRA protocols, and we advocate the inclusion

  14. Reminiscences of research on the chemistry and biology of natural sterols in insects, plants and humans

    PubMed Central

    IKEKAWA, Nobuo; FUJIMOTO, Yoshinori; ISHIGURO, Masaji

    2013-01-01

    Natural sterols often occur as a heterogeneous mixture of homologs, which had disturbed the progress of steroid research. Development and application of GC methodology overcame this difficulty and enabled us to obtain detailed sterol profiles. Together, fine synthesis of stereo-defined isomers and homologs of steroids having oxygenated side chains allowed us to compare them with natural samples as well as to investigate structure-activity relationship. Advance of HPLC technology also facilitated the determination of the stereochemical structure of naturally occurring steroidal compounds, which were obtained only in minute amounts. This review highlights three topics out of our steroid research that have been performed mainly at Tokyo Institute of Technology around 1970–1990. These are sterol metabolism in insects focusing on the mechanism of the conversion of plant sterols to cholesterol and ecdysone biosynthesis, the synthesis and biochemical research of active forms of vitamin D3 derivatives, and the synthesis and microanalysis of plant hormone brassinosteroids. PMID:24126284

  15. Evidence for evolution in response to natural selection in a contemporary human population

    PubMed Central

    Milot, Emmanuel; Mayer, Francine M.; Nussey, Daniel H.; Boisvert, Mireille; Pelletier, Fanie; Réale, Denis

    2011-01-01

    It is often claimed that modern humans have stopped evolving because cultural and technological advancements have annihilated natural selection. In contrast, recent studies show that selection can be strong in contemporary populations. However, detecting a response to selection is particularly challenging; previous evidence from wild animals has been criticized for both applying anticonservative statistical tests and failing to consider random genetic drift. Here we study life-history variation in an insular preindustrial French-Canadian population and apply a recently proposed conservative approach to testing microevolutionary responses to selection. As reported for other such societies, natural selection favored an earlier age at first reproduction (AFR) among women. AFR was also highly heritable and genetically correlated to fitness, predicting a microevolutionary change toward earlier reproduction. In agreement with this prediction, AFR declined from about 26–22 y over a 140-y period. Crucially, we uncovered a substantial change in the breeding values for this trait, indicating that the change in AFR largely occurred at the genetic level. Moreover, the genetic trend was higher than expected under the effect of random genetic drift alone. Our results show that microevolution can be detectable over relatively few generations in humans and underscore the need for studies of human demography and reproductive ecology to consider the role of evolutionary processes. PMID:21969551

  16. Natural selection of autocatalytic systems in flow as the universal mechanism of prebiotic evolution

    NASA Astrophysics Data System (ADS)

    Bartsev, S.; Mezhevikin, V.

    The problem of searching for extraterrestrial life is closely associated with the problem of origin of life in general and on the Earth. However convincing scientific concept of this event does not exist till now. The probability of casual occurrence of the elementary living cell from a set of abiogenous substances is so small, that from the point of natural-science methodological positions this variant of life origin should be excluded. It is necessary to assume the predecessors of cells were very simple, and their development, perfecting and thickening occurred gradually and in the certain sense neatly via natural selection. An assumption, that the predecessors of cells were elementary autocatalytic systems on the basis of the phase-isolated particles, and the mechanism of their selection was selection in flow with respect to kinetics parameters is put forward. In the paper probable directions of autocatalytic systems selection in flow inside a reactor of deal mixing are considered. As reali analog of in flow system of the kind the hydrothermal vent tube worms found in deep-sea waters could be considered. Thus, it is possible to select certain types of autocatalytic systems admitting an opportunity of "mutagenesis", and to plan experimental modeling of initial stages of prebiotic evolution under various physical-chemical conditions, including extraterrestrial ones. According to the concept, the life origin under the certain physical-chemical planetary conditions is the inevitable planetary phenomenon and key stages of this phenomenon allow not only theoretical, but also experimental analysis.

  17. Strong natural selection on juveniles maintains a narrow adult hybrid zone in a broadcast spawner.

    PubMed

    Prada, Carlos; Hellberg, Michael E

    2014-12-01

    Natural selection can maintain and help form species across different habitats, even when dispersal is high. Selection against inferior migrants (immigrant inviability) acts when locally adapted populations suffer high mortality on dispersal to unsuitable habitats. Habitat-specific populations undergoing divergent selection via immigrant inviability should thus show (1) a change in the ratio of adapted to nonadapted individuals among age/size classes and (2) a cline (defined by the environmental gradient) as selection counterbalances migration. Here we examine the frequencies of two depth-segregated lineages in juveniles and adults of a Caribbean octocoral, Eunicea flexuosa. Distributions of the two lineages in both shallow and deep environments were more distinct when inferred from adults than juveniles. Despite broad larval dispersal, we also found an extremely narrow hybrid zone (<100 m), with coincident clines for molecular and morphological characters of the host coral and its algal symbiont. Effective dispersal estimates derived from the hybrid zone are remarkably small (<20 m) for a broadcast spawner. The large selection coefficient against mismatched genotypes derived from cohort data is consistent with that from field transplant experiments. Narrow hybrid zones and limited effective dispersal may be a common outcome of long periods of postsettlement, prereproductive selection across steep ecological gradients. Strong diversifying selection provides a mechanism to explain the prevalence of depth-segregated sibling species in the sea. PMID:25438171

  18. Divergent natural selection promotes immigrant inviability at early and late stages of evolutionary divergence.

    PubMed

    Ingley, Spencer J; Johnson, Jerald B

    2016-03-01

    Natural selection's role in speciation has been of fundamental importance since Darwin first outlined his theory. Recently, work has focused on understanding how selection drives trait divergence, and subsequently reproductive isolation. "Immigrant inviability," a barrier that arises from selection against immigrants in their nonnative environment, appears to be of particular importance. Although immigrant inviability is likely ubiquitous, we know relatively little about how selection acts on traits to drive immigrant inviability, and how important immigrant inviability is at early-versus-late stages of divergence. We present a study evaluating the role of predation in the evolution of immigrant inviability in recently diverged population pairs and a well-established species pair of Brachyrhaphis fishes. We evaluate performance in a high-predation environment by assessing survival in the presence of a predator, and swimming endurance in a low-predation environment. We find strong signatures of local adaptation and immigrant inviability of roughly the same magnitude both early and late in divergence. We find remarkably conserved selection for burst-speed swimming (important in predator evasion), and selection for increased size in low-predation environments. Our results highlight the consistency with which selection acts during speciation, and suggest that similar factors might promote initial population differentiation and maintain differentiation at late stages of divergence. PMID:26831519

  19. Material selection for wellhead equipment exposed to chlorinated and natural seawater

    SciTech Connect

    Olsen, S.; Nice, P.; Strandmyr, O.; Maligas, M.; Vicic, J.

    1996-08-01

    Corrosion resistant alloys have been used in marine environments for their corrosion resistance. However, some of these materials are prone to localized corrosion, in particular crevice and pitting corrosion, in natural seawater. Injection water normally consists of de-oxygenated seawater, but, more recently either continuously or batch chlorinated and fully oxygenated seawater has been selected for this purpose because of their cost benefits. This investigation covers testing of corrosion resistant materials to aid in the selection of materials for wellhead equipment in an oxygenated and chlorinated seawater injection environment.

  20. Natural AChE Inhibitors from Plants and their Contribution to Alzheimer’s Disease Therapy

    PubMed Central

    Murray, Ana Paula; Faraoni, María Belén; Castro, María Julia; Alza, Natalia Paola; Cavallaro, Valeria

    2013-01-01

    As acetylcholinesterase (AChE) inhibitors are an important therapeutic strategy in Alzheimer’s disease, efforts are being made in search of new molecules with anti-AChE activity. The fact that naturally-occurring compounds from plants are considered to be a potential source of new inhibitors has led to the discovery of an important number of secondary metabolites and plant extracts with the ability of inhibiting the enzyme AChE, which, according to the cholinergic hypothesis, increases the levels of the neurotransmitter acetylcholine in the brain, thus improving cholinergic functions in patients with Alzheimer’s disease and alleviating the symptoms of this neurological disorder. This review summarizes a total of 128 studies which correspond to the most relevant research work published during 2006-2012 (1st semester) on plant-derived compounds, plant extracts and essential oils found to elicit AChE inhibition. PMID:24381530

  1. Plant selection for nest building by western lowland gorillas in Cameroon.

    PubMed

    Willie, Jacob; Tagg, Nikki; Petre, Charles-Albert; Pereboom, Zjef; Lens, Luc

    2014-01-01

    We examined 834 nests built by western lowland gorillas in Cameroon between July 2008 and July 2011 to identify the plant species used in their construction. Preference for each plant species for nesting was assessed using a 'preference index' calculated by combining information on the occurrence of each species in the forest and in the nests. Forty-six plant species representing about 15 % of the total number of species in the forest and 26 % of species used for nest building were frequently used by gorillas. Preference levels significantly varied among these species. Nests were mostly built with herbs of the families Marantaceae and Zingiberaceae and woody species such as Manniophyton fulvum (liana) and Alchornea floribunda (shrub). As observed in other gorilla populations, suitability for nest building and availability of gorilla food in stems were the likely determinants of plant selection. The total number of species used per nest ranged from 1 to 11, with an average of 4.9. This is high compared to other sites, emphasizing variability in the availability of nest building materials and habitat differences across the range of the western gorilla. Seasonal changes in the use of different habitat types for nesting did not appear to influence plant use for nest building as there was little variation in plant selection across seasons or the composition of nests. Our findings suggest that gorillas non-randomly select plant species to build nests, and use a particular set of species combined at varying proportions, with no clear seasonal or spatial patterns. PMID:23732768

  2. Phyto extraction and accumulation of mercury in selected plant species grown in soil contaminated with different mercury compounds

    SciTech Connect

    Su, Y.; Han, F.; Shiyab, S.; Monts, D.L.

    2007-07-01

    The objective of our research is to screen and search for suitable plant species for phyto-remediation of mercury-contaminated soil. Currently our effort is specifically focused on mercury removal from the U.S. Department of Energy's (DOE) Oak Ridge Site, where mercury contamination is a major concern in the Y-12 Watershed area. In order to cost effectively implement those remediation efforts currently planned for FY09, it is necessary now to obtain an improved understanding of biological means of removing mercury and mercury compounds from the Oak Ridge ecosystem. Phyto-remediation is a technology that uses various plants to degrade, extract, contain, or immobilize contaminants from soil and water. In particular, phyto-extraction is the uptake of contaminants by plant roots and translocation within the plants to shoots or leaves. Contaminants are generally removed by harvesting the plants. We have investigated phyto-extraction of mercury from contaminated soil by using some of the known metal accumulating wild plants since no natural plant species with mercury hyper-accumulating properties has yet been identified. Different natural plant species have been studied for mercury uptake, accumulation, toxicity and overall mercury removal efficiency. Various mercury compounds, such as HgS, HgCl{sub 2} and Hg(NO{sub 3}){sub 2}, were used as contaminant sources. Different types of soil were examined and chosen for phyto-remediation experiments. We have applied microscopy and diffuse reflectance spectrometry as well as conventional analytical chemistry to monitor the phyto-remediation processes of mercury uptake, translocation and accumulation; and the physiological impact of mercury contaminants on selected plant species. Our results indicate that certain plant species, such as beard grass (Polypogon monospeliensis), accumulated a very limited amount of mercury in the shoots (<65 mg/kg), even though root mercury accumulation is significant (maximum 2298 mg

  3. Pharmacological and Phytochemical Appraisal of Selected Medicinal Plants from Jordan with Claimed Antidiabetic Activities

    PubMed Central

    Afifi, Fatma U.; Kasabri, Violet

    2013-01-01

    Plant species have long been regarded as possessing the principal ingredients used in widely disseminated ethnomedical practices. Different surveys showed that medicinal plant species used by the inhabitants of Jordan for the traditional treatment of diabetes are inadequately screened for their therapeutic/preventive potential and phytochemical findings. In this review, traditional herbal medicine pursued indigenously with its methods of preparation and its active constituents are listed. Studies of random screening for selective antidiabetic bioactivity and plausible mechanisms of action of local species, domesticated greens, or wild plants are briefly discussed. Recommended future directives incurring the design and conduct of comprehensive trials are pointed out to validate the usefulness of these active plants or bioactive secondary metabolites either alone or in combination with existing conventional therapies. PMID:24482764

  4. Genetic basis and selection for life-history trait plasticity on alternative host plants for the cereal aphid Sitobion avenae.

    PubMed

    Dai, Xinjia; Gao, Suxia; Liu, Deguang

    2014-01-01

    Sitobion avenae (F.) can survive on various plants in the Poaceae, which may select for highly plastic genotypes. But phenotypic plasticity was often thought to be non-genetic, and of little evolutionary significance historically, and many problems related to adaptive plasticity, its genetic basis and natural selection for plasticity have not been well documented. To address these questions, clones of S. avenae were collected from three plants, and their phenotypic plasticity under alternative environments was evaluated. Our results demonstrated that nearly all tested life-history traits showed significant plastic changes for certain S. avenae clones with the total developmental time of nymphs and fecundity tending to have relatively higher plasticity for most clones. Overall, the level of plasticity for S. avenae clones' life-history traits was unexpectedly low. The factor 'clone' alone explained 27.7-62.3% of the total variance for trait plasticities. The heritability of plasticity was shown to be significant in nearly all the cases. Many significant genetic correlations were found between trait plasticities with a majority of them being positive. Therefore, it is evident that life-history trait plasticity involved was genetically based. There was a high degree of variation in selection coefficients for life-history trait plasticity of different S. avenae clones. Phenotypic plasticity for barley clones, but not for oat or wheat clones, was frequently found to be under significant selection. The directional selection of alternative environments appeared to act to decrease the plasticity of S. avenae clones in most cases. G-matrix comparisons showed significant differences between S. avenae clones, as well as quite a few negative covariances (i.e., trade-offs) between trait plasticities. Genetic basis and evolutionary significance of life-history trait plasticity were discussed. PMID:25181493

  5. Macroevolutionary patterns of bumblebee body size: detecting the interplay between natural and sexual selection

    PubMed Central

    del Castillo, Raúl Cueva; Fairbairn, Daphne J

    2012-01-01

    Bumblebees and other eusocial bees offer a unique opportunity to analyze the evolution of body size differences between sexes. The workers, being sterile females, are not subject to selection for reproductive function and thus provide a natural control for parsing the effects of selection on reproductive function (i.e., sexual and fecundity selection) from other natural selection. Using a phylogenetic comparative approach, we explored the allometric relationships among queens, males, and workers in 70 species of bumblebees (Bombus sp.). We found hyperallometry in thorax width for males relative to workers, indicating greater evolutionary divergence of body size in males than in sterile females. This is consistent with the hypothesis that selection for reproductive function, most probably sexual selection, has caused divergence in male size among species. The slope for males on workers was significantly steeper than that for queens on workers and the latter did not depart from isometry, providing further evidence of greater evolutionary divergence in male size than female size, and no evidence that reproductive selection has accelerated divergence of females. We did not detect significant hyperallometry when male size was regressed directly on queen size and our results thus add the genus Bombus to the increasing list of clades that have female-larger sexual size dimorphism and do not conform to Rensch's rule when analyzed according to standard methodology. Nevertheless, by using worker size as a common control, we were able to demonstrate that bumblee species do show the evolutionary pattern underlying Rensch's rule, that being correlated evolution of body size in males and females, but with greater evolutionary divergence in males. PMID:22408725

  6. The Role of Selection in Shaping Diversity of Natural M. tuberculosis Populations

    PubMed Central

    Pepperell, Caitlin S.; Casto, Amanda M.; Kitchen, Andrew; Granka, Julie M.; Cornejo, Omar E.; Holmes, Eddie C.; Birren, Bruce; Galagan, James; Feldman, Marcus W.

    2013-01-01

    Mycobacterium tuberculosis (M.tb), the cause of tuberculosis (TB), is estimated to infect a new host every second. While analyses of genetic data from natural populations of M.tb have emphasized the role of genetic drift in shaping patterns of diversity, the influence of natural selection on this successful pathogen is less well understood. We investigated the effects of natural selection on patterns of diversity in 63 globally extant genomes of M.tb and related pathogenic mycobacteria. We found evidence of strong purifying selection, with an estimated genome-wide selection coefficient equal to −9.5×10−4 (95% CI −1.1×10−3 to −6.8×10−4); this is several orders of magnitude higher than recent estimates for eukaryotic and prokaryotic organisms. We also identified different patterns of variation across categories of gene function. Genes involved in transport and metabolism of inorganic ions exhibited very low levels of non-synonymous polymorphism, equivalent to categories under strong purifying selection (essential and translation-associated genes). The highest levels of non-synonymous variation were seen in a group of transporter genes, likely due to either diversifying selection or local selective sweeps. In addition to selection, we identified other important influences on M.tb genetic diversity, such as a 25-fold expansion of global M.tb populations coincident with explosive growth in human populations (estimated timing 1684 C.E., 95% CI 1620–1713 C.E.). These results emphasize the parallel demographic histories of this obligate pathogen and its human host, and suggest that the dominant effect of selection on M.tb is removal of novel variants, with exceptions in an interesting group of genes involved in transportation and defense. We speculate that the hostile environment within a host imposes strict demands on M.tb physiology, and thus a substantial fitness cost for most new mutations. In this respect, obligate bacterial pathogens may differ from

  7. Hepatic gene expression in herbivores on diets with natural and novel plant secondary compounds.

    PubMed

    Magnanou, Elodie; Malenke, Jael R; Dearing, M Denise

    2013-09-01

    Herbivores are predicted to evolve appropriate mechanisms to process the plant secondary compounds (PSCs) in their diet, and these mechanisms are likely specific to particular suites of PSCs. Changes in diet composition over evolutionary time should select for appropriate alterations in metabolism of the more recent dietary components. We investigated differences in gene expression profiles in the liver with respect to prior ecological and evolutionary experience with PSCs in the desert woodrat, Neotoma lepida. This woodrat species has populations in the Mojave Desert that have switched from feeding on juniper to feeding on creosote at the end of the Holocene as well as populations in the Great Basin Desert that still feed on the ancestral diet of juniper and are naïve to creosote. Juniper and creosote have notable differences in secondary chemistry. Woodrats from the Mojave and Great Basin Deserts were subjected to a fully crossed feeding trial on diets of juniper and creosote after which their livers were analyzed for gene expression. Hybridization of hepatic mRNAs to laboratory rat microarrays resulted in a total of 20,031 genes that met quality control standards. We analyzed differences in large-scale patterns of liver gene expression with respect to GO term enrichment. Diet had a larger effect on gene expression than population membership. However, woodrats with no prior evolutionary experience to the diet upregulated a greater proportion of genes indicative of physiological stress compared with those on their natural diet. This pattern may be the result of a naïve animal's attempting to mitigate physiological damage caused by novel PSCs. PMID:23859940

  8. Natural selection of memory-one strategies for the iterated prisoner's dilemma.

    PubMed

    Kraines, D P; Kraines, V Y

    2000-04-21

    In the iterated Prisoner's Dilemma, mutually cooperative behavior can become established through Darwinian natural selection. In simulated interactions of stochastic memory-one strategies for the Iterated Prisoner's Dilemma, Nowak and Sigmund discovered that cooperative agents using a Pavlov (Win-Stay Lose-Switch) type strategy eventually dominate a random population. This emergence follows more directly from a deterministic dynamical system based on differential reproductive success or natural selection. When restricted to an environment of memory-one agents interacting in iterated Prisoner's Dilemma games with a 1% noise level, the Pavlov agent is the only cooperative strategy and one of very few others that cannot be invaded by a similar strategy. Pavlov agents are trusting but no suckers. They will exploit weakness but repent if punished for cheating. PMID:10736212

  9. Stochastic effects in adaptive reconstruction of body damage: implied the creativity of natural selection.

    PubMed

    Xiao, Bo; Cui, Li-Qiang; Chen, Tian-Ming; Lian, Bin

    2015-11-01

    After an injury occurs, mechanical/biochemical loads on muscles influence the composition and structure of recovering muscles; this effect likely occurs in other tissues, cells and biological molecules as well owing to the similarity, interassociation and interaction among biochemical reactions and molecules. The 'damage and reconstruction' model provides an explanation for how an ideal cytoarchitecture is created by reducing components not suitable for bearing loads; in this model, adaptive changes are induced by promoting the stochasticity of biochemical reactions. Biochemical and mechanical loads can direct the stochasticity of biochemical reactions, which can in turn induce cellular changes. Thus, mechanical and biochemical loads, under natural selection pressure, modify the direction of cell- and tissue-level changes and guide the formation of new structures and traits, thereby influencing microevolution. In summary, the 'damage and reconstruction' model accounts for the role of natural selection in the formation of new organisms, helps explain punctuated equilibrium, and illustrates how macroevolution arises from microevolution. PMID:26153081

  10. Biological Activity of Peanut (Arachis hypogaea) Phytoalexins and Selected Natural and Synthetic Stilbenoids

    PubMed Central

    SOBOLEV, VICTOR S.; KHAN, SHABANA I.; TABANCA, NURHAYAT; WEDGE, DAVID E.; MANLY, SUSAN P.; CUTLER, STEPHEN J.; COY, MONIQUE R.; BECNEL, JAMES J.; NEFF, SCOTT A.; GLOER, JAMES B.

    2011-01-01

    The peanut plant (Arachis hypogaea L.), when infected by a microbial pathogen, is capable of producing stilbene-derived compounds that are considered antifungal phytoalexins. In addition, the potential health benefits of other stilbenoids from peanuts, including resveratrol and pterostilbene, have been acknowledged by several investigators. Despite considerable progress in peanut research, relatively little is known about the biological activity of the stilbenoid phytoalexins. This study investigated the activities of some of these compounds in a broad spectrum of biological assays. Since peanut stilbenoids appear to play roles in plant defense mechanisms, they were evaluated for their effects on economically important plant pathogenic fungi of the genera Colletotrichum, Botrytis, Fusarium, and Phomopsis. We further investigated these peanut phytoalexins, together with some related natural and synthetic stilbenoids (a total of 24 compounds) in a panel of bioassays to determine their anti-inflammatory, cytotoxic, and antioxidant activities in mammalian cells. Several of these compounds were also evaluated as mammalian opioid receptor competitive antagonists. Assays for adult mosquito and larvae toxicity were also performed. The results of these studies reveal that peanut stilbenoids, as well as related natural and synthetic stilbene derivatives, display a diverse range of biological activities. PMID:21314127

  11. Clonality, genetic diversity and support for the diversifying selection hypothesis in natural populations of a flower-living yeast.

    PubMed

    Herrera, C M; Pozo, M I; Bazaga, P

    2011-11-01

    Vast amounts of effort have been devoted to investigate patterns of genetic diversity and structuring in plants and animals, but similar information is scarce for organisms of other kingdoms. The study of the genetic structure of natural populations of wild yeasts can provide insights into the ecological and genetic correlates of clonality, and into the generality of recent hypotheses postulating that microbial populations lack the potential for genetic divergence and allopatric speciation. Ninety-one isolates of the flower-living yeast Metschnikowia gruessii from southeastern Spain were DNA fingerprinted using amplified fragment length polymorphism (AFLP) markers. Genetic diversity and structuring was investigated with band-based methods and model- and nonmodel-based clustering. Linkage disequilibrium tests were used to assess reproduction mode. Microsite-dependent, diversifying selection was tested by comparing genetic characteristics of isolates from bumble bee vectors and different floral microsites. AFLP polymorphism (91%) and genotypic diversity were very high. Genetic diversity was spatially structured, as shown by amova (Φ(st)  = 0.155) and clustering. The null hypothesis of random mating was rejected, clonality seeming the prevailing reproductive mode in the populations studied. Genetic diversity of isolates declined from bumble bee mouthparts to floral microsites, and frequency of five AFLP markers varied significantly across floral microsites, thus supporting the hypothesis of diversifying selection on clonal lineages. Wild populations of clonal fungal microbes can exhibit levels of genetic diversity and spatial structuring that are not singularly different from those shown by sexually reproducing plants or animals. Microsite-dependent, divergent selection can maintain high local and regional genetic diversity in microbial populations despite extensive clonality. PMID:21851437

  12. Darwin's Arguments in Favour of Natural Selection and Against Special Creationism

    NASA Astrophysics Data System (ADS)

    Nola, Robert

    2013-02-01

    In many places in The Origin of Species, Darwin compares his own theory of Natural Selection favourably with Special Creationism which comes off as a bad second best. He does this using some version of the argument form known as `Inference to the Best Explanation'. The first part of this paper is methodological. It considers Whewell's notion of consilience, that is, the way in which theories can get additional confirmation through unifying otherwise disparate and independent facts. Then it considers various forms of inference to the best explanation. The second part of the paper applies these methodological considerations to an analysis of some of the many passages in Origin where Darwin presents his case in favour of Natural Selection. This gives a far superior explanation of biological facts compared with Special Creationism which provides either an inferior explanation or no explanation at all. Contrary to the view that Creationism should not be taught, the passages from Darwin show at least that it should be understood if only to show that it offers no explanation of a wide range of obvious biological facts. As such the passages in Origin in which Darwin presents his case against Creationism can serve as a series of excellent exercises in getting students to think about Natural Selection as opposed to Creationism. For this reason alone they ought to be better known. In addition, Darwin's point in these passages can only be understood using principles of scientific method, such as inference to the best explanation, which are essential in showing that Natural Selection is to be preferred to Creationism.

  13. Darwin's passionate environmentalism or the dangerous fallacy of the 'All-sufficiency of natural selection' theory.

    PubMed

    Marsh, David

    2012-01-01

    Following his last edition of the Origin of Species in 1872, Darwin spent much of the rest of his life searching for possible mechanisms, such as the pangenes in the blood, which would communicate information from the environment to the genome. In each of his six editions of the 'Origin', he stated that there were two forces in evolution - natural selection and conditions of existence. Of the two, he claims that the latter is the more powerful. In so doing, he recognized that natural selection could only operate within the bounds of possibility, that is the environment. August Weismann claimed that conditions of existence had no place in evolution. His publication, the 'All-sufficiency of natural selection', was based on mutilation (cutting tails of rodents and watching the next generation grow tails), which has nothing to do with Darwin's concept of conditions of existence. Nonetheless, evolutionary biologists in general followed the line of the 'all sufficiency' theory and ignored Darwin's conditions of existence, which in other words means the environment. Natural selection has a weak predictive power as it is based on random events. However, the conditions of existence have, by contrast, strong predictive powers that can be tested. The environmental views of two of the greatest evolutionists, Lamarck and Darwin, have been consistently ignored by most evolution theorists who came after them, continuing for over 200 years. Looking at the fossil record through the eyes of Darwin's conditions of existence, not to mention the recent changes in height and shape over the last century, it is possible to draw important conclusions about the past and predictions of the future. With new knowledge of epigenetics, it is perhaps time that Darwin's conditions of existence were given a second hearing. PMID:22544777

  14. Natural selection theory in non-majors' biology: Instruction, assessment and conceptual difficulty

    NASA Astrophysics Data System (ADS)

    Anderson, Dianne L.

    Evolution by natural selection is the dominant and unifying theme in biology, yet many college students hold alternative conceptions about the topic even after completing general biology. To develop effective instructional strategies and track conceptual understanding, it is useful to have a detailed assessment tool easily used with large classes. This study presents the Conceptual Inventory of Natural Selection (CINS), a distractor-driven twenty item multiple-choice test that assesses understanding of ten concepts related to natural selection: biotic potential, stable populations, limited natural resources, limited survival, variation within a population, variation inherited, differential survival, change in populations, origin of variation, and origin of species. Development, refinement, and field-testing of individual CINS items are presented, and validity, readability, reliability and factor analysis of the CINS are described. There was significant correlation between student performance on the posttest CINS and end-of-semester interviews suggesting that the CINS is a useful classroom tool. The CINS was used as both a pretest and posttest to determine relative difficulty of the concepts among college students. The three most challenging concepts were random origin of variation, how populations change over time due to changing proportions of alleles, and how new species originate. Many students chose distractors including "need" as a driving force. Results support the use of non-traditional methods, as only students in such classes demonstrated any improvement on the CINS posttest. Pre and posttesting with the CINS was also used to assess relative effectiveness of using two types of supplemental reading materials (selections from narrative, non-textbook sources or from other general biology textbooks) in a general biology course. These results suggest that specific content of readings was more important than style of the readings. Implications for teaching both

  15. Harvesting the biosynthetic machineries that cultivate a variety of indispensable plant natural products.

    PubMed

    Vickery, Christopher R; La Clair, James J; Burkart, Michael D; Noel, Joseph P

    2016-04-01

    Plants are a sustainable resource for valuable natural chemicals best illustrated by large-scale farming centered on specific products. Here, we review recent discoveries of plant metabolic pathways producing natural products with unconventional biomolecular structures. Prenylation of polyketides by aromatic prenyltransferases (aPTases) ties together two of the major groups of plant specialized chemicals, terpenoids and polyketides, providing a core modification leading to new bioactivities and downstream metabolic processing. Moreover, PTases that biosynthesize Z-terpenoid precursors for small molecules such as lycosantalene have recently been found in the tomato family. Gaps in our understanding of how economically important compounds such as cannabinoids are produced are being identified using next-generation 'omics' to rapidly advance biochemical breakthroughs at an unprecedented rate. For instance, olivetolic acid cyclase, a polyketide synthase (PKS) co-factor from Cannabis sativa, directs the proper cyclization of a polyketide intermediate. Elucidations of spatial and temporal arrangements of biosynthetic enzymes into metabolons, such as those used to control the efficient production of natural polymers such as rubber and defensive small molecules such as linamarin and lotaustralin, provide blueprints for engineering streamlined production of plant products. PMID:26851514

  16. Antiplasmodial activity of ethanolic extracts of some selected medicinal plants from the northwest of Iran.

    PubMed

    Sangian, Hadi; Faramarzi, Hossein; Yazdinezhad, Alireza; Mousavi, Seyed Javad; Zamani, Zahra; Noubarani, Maryam; Ramazani, Ali

    2013-11-01

    The effectiveness of antimalarial drugs is declining at an ever accelerating rate, with consequent increase in malaria-related morbidity and mortality. The newest antiplasmodial drug from plants is needed to overcome this problem. The aim of this study was to assess antimalarial activity of the ethanolic extracts of 10 different medicinal plants from eight families against Plasmodium falciparum chloroquine-sensitive 3D7 strain. The selection of the hereby studied plants was based on the existing information on their local ethnobotanic history. Plants were dried, powdered, and macerated in a hydroalcoholic solution. Resulting extracts have been assessed for in vitro and in vivo antimalarial and brine shrimp toxicity activities. Of 10 plant species tested, four plants: Althea officinalis L. (Malvaceae), Myrtus communis Linn (Myrtaceae), Plantago major (Plantaginaceae), and Glycyrrhiza glabra L. (Papilionaceae) displayed promising antimalarial activity in vitro (50% inhibitory concentration values of 62.77, 42.18, 40.00, and 13.56 μg/mL, respectively) with no toxicity against brine shrimp larvae. The crude extracts of three active plants, G. glabra, M. communis, and A. officinalis, also significantly reduced parasitemia in vivo in female Swiss albino mice at a dose of 400 mg/kg compared to no treatment. Antiplasmodial activities of extracts of A. officinalis and M. communis are reported for the first time. PMID:23922204

  17. A signal integration model of thymic selection and natural regulatory T cell commitment.

    PubMed

    Khailaie, Sahamoddin; Robert, Philippe A; Toker, Aras; Huehn, Jochen; Meyer-Hermann, Michael

    2014-12-15

    The extent of TCR self-reactivity is the basis for selection of a functional and self-tolerant T cell repertoire and is quantified by repeated engagement of TCRs with a diverse pool of self-peptides complexed with self-MHC molecules. The strength of a TCR signal depends on the binding properties of a TCR to the peptide and the MHC, but it is not clear how the specificity to both components drives fate decisions. In this study, we propose a TCR signal-integration model of thymic selection that describes how thymocytes decide among distinct fates, not only based on a single TCR-ligand interaction, but taking into account the TCR stimulation history. These fates are separated based on sustained accumulated signals for positive selection and transient peak signals for negative selection. This spans up the cells into a two-dimensional space where they are either neglected, positively selected, negatively selected, or selected as natural regulatory T cells (nTregs). We show that the dynamics of the integrated signal can serve as a successful basis for extracting specificity of thymocytes to MHC and detecting the existence of cognate self-peptide-MHC. It allows to select a self-MHC-biased and self-peptide-tolerant T cell repertoire. Furthermore, nTregs in the model are enriched with MHC-specific TCRs. This allows nTregs to be more sensitive to activation and more cross-reactive than conventional T cells. This study provides a mechanistic model showing that time integration of TCR-mediated signals, as opposed to single-cell interaction events, is needed to gain a full view on the properties emerging from thymic selection. PMID:25392533

  18. Assessment of range planting as a conservation practice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural Resource Conservation Service (NRCS) Range Planting - Conservation Practice Standards provide guidelines for making decisions about seedbed preparation, planting methods, plant materials selection, seeding rate, seeding depth, timing of seeding, post-planting management, and weed-control. ...

  19. Implications of quantum metabolism and natural selection for the origin of cancer cells and tumor progression

    NASA Astrophysics Data System (ADS)

    Davies, Paul; Demetrius, Lloyd A.; Tuszynski, Jack A.

    2012-03-01

    Empirical studies give increased support for the hypothesis that the sporadic form of cancer is an age-related metabolic disease characterized by: (a) metabolic dysregulation with random abnormalities in mitochondrial DNA, and (b) metabolic alteration - the compensatory upregulation of glycolysis to offset mitochondrial impairments. This paper appeals to the theory of Quantum Metabolism and the principles of natural selection to formulate a conceptual framework for a quantitative analysis of the origin and proliferation of the disease. Quantum Metabolism, an analytical theory of energy transduction in cells inspired by the methodology of the quantum theory of solids, elucidates the molecular basis for differences in metabolic rate between normal cells, utilizing predominantly oxidative phosphorylation, and cancer cells utilizing predominantly glycolysis. The principles of natural selection account for the outcome of competition between the two classes of cells. Quantum Metabolism and the principles of natural selection give an ontogenic and evolutionary rationale for cancer proliferation and furnish a framework for effective therapeutic strategies to impede the spread of the disease.

  20. Does natural selection organize ecosystems for the maintenance of high productivity and diversity?

    PubMed Central

    Leigh, Egbert Giles; Vermeij, Geerat Jacobus

    2002-01-01

    Three types of evidence suggest that natural ecosystems are organized for high productivity and diversity: (i) changes not previously experienced by a natural ecosystem, such as novel human disturbances, tend to diminish its productivity and/or diversity, just as 'random' changes in a machine designed for a function usually impair its execution of that function; (ii) humans strive to recreate properties of natural ecosystems to enhance productivity of artificial ones, as farmers try to recreate properties of natural soils in their fields; and (iii) productivity and diversity have increased during the Earth's history as a whole, and after every major biotic crisis. Natural selection results in ecosystems organized to maintain high productivity of organic matter and diversity of species, just as competition among individuals in Adam Smith's ideal economy favours high production of wealth and diversity of occupations. In nature, poorly exploited energy attracts more efficient users. This circumstance favours the opening of new ways of life and more efficient recycling of resources, and eliminates most productivity-reducing 'ecological monopolies'. Ecological dominants tend to be replaced by successors with higher metabolism, which respond to more stimuli and engage in more varied interactions. Finally, increasingly efficient predators and herbivores favour faster turnover of resources. PMID:12079531

  1. Arsenic and other heavy metal accumulation in plants and algae growing naturally in contaminated area of West Bengal, India.

    PubMed

    Singh, N K; Raghubanshi, A S; Upadhyay, A K; Rai, U N

    2016-08-01

    The present study was conducted to quantify the arsenic (As) and other heavy metal concentrations in the plants and algae growing naturally in As contaminated blocks of North-24-Pargana and Nandia district, West Bengal, India to assess their bioaccumulation potential. The plant species included five macrophytes and five algae were collected from the nine selected sites for estimation of As and other heavy metals accumulated therein by using Inductively Coupled Plasma Mass Spectrophotometer (ICP-MS). Results revealed that maximum As concentration (117mgkg(-1)) was recorded in the agricultural soil at the Barasat followed by Beliaghat (111mgkg(-1)) sites of North-24-Pargana. Similarly, concentration of selenium (Si, 249mgkg(-1)), lead (Pb, 79.4mgkg(-1)), chromium (Cr, 138mgkg(-1)) was also found maximum in the soil at Barasat and cadmium (Cd, 163mgkg(-1)) nickel (Ni, 36.5mgkg(-1)) at Vijaynagar site. Among the macrophytes, Eichhornia crassipes found more dominating species in As contaminated area and accumulate As (597mgkg(-1)) in the shoot at kanchrapara site. The Lemna minor found to accumulate maximum As (735mgkg(-1)) in the leaves at Sonadanga and Pistia stratiotes accumulated minimum As (24.5mgkg(-1)) in the fronds from Ranaghat site. In case of diatoms, maximum As (760mgkg(-1)) was accumulated at Kanchrapara site followed by Hydrodictiyon reticulatum (403mgkg(-1)) at the Ranaghat site. High concentration of As and other heavy metal in soil indicates long term effects of irrigation with contaminated ground water, however, high concentration of heavy metals in naturally growing plants and algae revealed their mobilization through leaching and possible food chain contamination. Therefore, efficient heavy metal accumulator macrophytes Eichhornia crassipes, Lemna minor, Spirodela polyrhiza may be exploited in removing metals from contaminated water by developing a plant based treatment system. However, As accumulator algal species may be used as a bioresource for

  2. Past and present effectiveness of protected areas for conservation of naturally and anthropogenically rare plant species.

    PubMed

    Vellak, Ain; Tuvi, Eva-Liis; Reier, Ülle; Kalamees, Rein; Roosaluste, Elle; Zobel, Martin; Pärtel, Meelis

    2009-06-01

    The Global Strategy of Plant Conservation states that at least 60% of threatened plant species should be within protected areas. This goal has been met in some regions with long traditions of plant protection. We used gap analysis to explore how particular groups of species of conservation interest, representing different types of natural or anthropogenic rarity, have been covered by protected areas on a national scale in Estonia during the last 100 years. Species-accumulation curves indicated that plant species that are naturally rare (restricted global or local distribution, always small populations, or very rare habitat requirements) needed almost twice as many protected areas to reach the 60% target as plant species that are rare owing to lack of suitable management (species depending on grassland management, moderate forest disturbances, extensive traditional agriculture, or species potentially threatened by collecting). Temporal analysis of the establishment of protected areas suggested that grouping plant species according to the predominant cause of rarity accurately reflected the history of conservation decision making. Species found in very rare habitats have previously received special conservation attention; species dependent on traditional extensive agriculture have been largely ignored until recently. Legislative initiative and new nature-protection schemes (e.g., Natura 2000, network of protected areas in the European Union) have had a positive influence on all species groups. Consequently, the species groups needing similar action for their conservation are sensitive indicators of the effectiveness of protected-area networks. Different species groups, however, may not be uniformly conserved within protected areas, and all species groups should fulfill the target of 60% coverage within protected areas. PMID:19128324

  3. Form and nature of precopulatory sexual selection in both sexes of a moth

    NASA Astrophysics Data System (ADS)

    Xu, Jin; Wang, Qiao

    2010-07-01

    Sexual selection is a process that operates through intrasexual competition and intersexual choice for reproduction in both sexes. Here, we report our work on a polygamous moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), aiming to infer the form and nature of precopulatory sexual selection in males and females. We show that, although a number of traits measured in each sex are correlated with mating success, the primary selection trait in females appears to be abdominal thickness and that in males is aedeagus length. As the female’s abdominal thickness is a reliable signal about the number and developmental stage of eggs, males who select females with thicker abdomens for mating will gain reproductive benefit, i.e., fertilizing more mature eggs. For females, earlier maturation of their eggs makes the females more likely to achieve mating earlier in an uncertain world where there is no guarantee that they will find more males in the future. Sexual selection appears to be the important force behind the evolution of fast egg maturation in females. We show that, under a male-biased sex ratio, more than 20% of mating fails within a few minutes after the aedeagus has penetrated into the female’s genitalia, suggesting that females can assess the features of the male aedeagus before allowing insemination to occur. Dissection and examination of both sexes suggest that a longer aedeagus enhances mating and fertilization efficiency in this species, supporting the notion that sexual selection is a primary force in the evolution of genital variance.

  4. Evaluation of anti-inflammatory activity of selected medicinal plants of Khyber Pakhtunkhwa, Pakistan.

    PubMed

    Khuda, Fazli; Iqbal, Zafar; Khan, Ayub; Zakiullah; Shah, Yasar; Ahmad, Lateef; Nasir, Fazli; Hassan, Muhammad; Ismail; Shah, Waheed Ali

    2014-03-01

    In present study, the anti-inflammatory potential of three medicinal plants, Xanthium strumarium, Achyranthes aspera and Duchesnea indica were evaluated, using both in vitro and in vivo assays. Carrageenan induced hind paw edema model was used to carry out the in vivo anti-inflammatory activity, while for in vitro screening lipoxygenase inhibition assay was used. Crude extract of all the selected plants depicted significant (plt;0.001) anti-inflammatory activity, at late phase of inflammation. Achyranthes aspera also showed considerable anti-inflammatory activity (47%) at relatively lower concentration (200 mg/ml), at the initial phase of inflammation. Similarly the ethyl acetate fraction of all the selected plants showed significant lipoxygenase inhibition activity when compared with the standard drug (Baicalein). The results obtained from both in vitro and in vivo anti-inflammatory activity suggest that the ethyl acetate fraction of the crude extract of all the selected plants can be used for the isolation of new lead compounds with better anti-inflammatory activity. PMID:24577927

  5. Polymer Selection Approach for Commonly and Uncommonly Used Natural Fibers Under Uncertainty Environments

    NASA Astrophysics Data System (ADS)

    AL-Oqla, Faris M.; Sapuan, S. M.

    2015-07-01

    Factors like awareness of the scarcity of non-renewable natural resources, high petroleum prices, and demands for environmental sustainability, as well as reducing the amount of environmental pollution, have led to a renewed interest in natural fiber reinforced polymer composites as a potential bio-based material type. The best polymer matrix type in view of the wide range of conflicting criteria to form a polymeric-based composite material suitable for sustainable industry under an uncertainty environment has still not been sufficiently determined. This work introduces a selection model to evaluate the available polymers for natural fibers to enhance the industrial sustainability theme. The model built was developed to evaluate various polymer types and to determine their relative merits taking account of various conflicting criteria for both commonly used and uncommonly used natural fibers utilizing the analytical hierarchy process technique. It was found that the choice of the best polymer type for a certain fiber type depends strongly on the polymers' intrinsic desirable conflicting characteristics. Polymers evaluations are illustrated for different technical criteria in order to facilitate the polymer selection process for various industrial applications with high confidence levels.

  6. The roles of genetic drift and natural selection in quantitative trait divergence along an altitudinal gradient in Arabidopsis thaliana

    PubMed Central

    Luo, Y; Widmer, A; Karrenberg, S

    2015-01-01

    Understanding how natural selection and genetic drift shape biological variation is a central topic in biology, yet our understanding of the agents of natural selection and their target traits is limited. We investigated to what extent selection along an altitudinal gradient or genetic drift contributed to variation in ecologically relevant traits in Arabidopsis thaliana. We collected seeds from 8 to 14 individuals from each of 14 A. thaliana populations originating from sites between 800 and 2700 m above sea level in the Swiss Alps. Seed families were grown with and without vernalization, corresponding to winter-annual and summer-annual life histories, respectively. We analyzed putatively neutral genetic divergence between these populations using 24 simple sequence repeat markers. We measured seven traits related to growth, phenology and leaf morphology that are rarely reported in A. thaliana and performed analyses of altitudinal clines, as well as overall QST-FST comparisons and correlation analyses among pair-wise QST, FST and altitude of origin differences. Multivariate analyses suggested adaptive differentiation along altitude in the entire suite of traits, particularly when expressed in the summer-annual life history. Of the individual traits, a decrease in rosette leaf number in the vegetative state and an increase in leaf succulence with increasing altitude could be attributed to adaptive divergence. Interestingly, these patterns relate well to common within- and between-species trends of smaller plant size and thicker leaves at high altitude. Our results thus offer exciting possibilities to unravel the underlying mechanisms for these conspicuous trends using the model species A. thaliana. PMID:25293874

  7. Natural selection for the Duffy-null allele in the recently admixed people of Madagascar.

    PubMed

    Hodgson, Jason A; Pickrell, Joseph K; Pearson, Laurel N; Quillen, Ellen E; Prista, António; Rocha, Jorge; Soodyall, Himla; Shriver, Mark D; Perry, George H

    2014-08-22

    While gene flow between distantly related populations is increasingly recognized as a potentially important source of adaptive genetic variation for humans, fully characterized examples are rare. In addition, the role that natural selection for resistance to vivax malaria may have played in the extreme distribution of the protective Duffy-null allele, which is nearly completely fixed in mainland sub-Saharan Africa and absent elsewhere, is controversial. We address both these issues by investigating the evolution of the Duffy-null allele in the Malagasy, a recently admixed population with major ancestry components from both East Asia and mainland sub-Saharan Africa. We used genome-wide genetic data and extensive computer simulations to show that the high frequency of the Duffy-null allele in Madagascar can only be explained in the absence of positive natural selection under extreme demographic scenarios involving high genetic drift. However, the observed genomic single nucleotide polymorphism diversity in the Malagasy is incompatible with such extreme demographic scenarios, indicating that positive selection for the Duffy-null allele best explains the high frequency of the allele in Madagascar. We estimate the selection coefficient to be 0.066. Because vivax malaria is endemic to Madagascar, this result supports the hypothesis that malaria resistance drove fixation of the Duffy-null allele in mainland sub-Saharan Africa. PMID:24990677

  8. Footprints of divergent selection in natural populations of Castanopsis fargesii (Fagaceae)

    PubMed Central

    Li, C; Sun, Y; Huang, H W; Cannon, C H

    2014-01-01

    Given predicted rapid climate change, an understanding of how environmental factors affect genetic diversity in natural populations is important. Future selection pressures are inherently unpredictable, so forest management policies should maintain both overall diversity and identify genetic markers associated with the environmental factors expected to change most rapidly, like temperature and rainfall. In this study, we genotyped 648 individuals in 28 populations of Castanopsis fargesii (Fagaceae) using 32 expressed sequence tag (EST)-derived microsatellite markers. After removing six loci that departed from Hardy–Weinberg equilibrium, we measured genetic variation, population structure and identified candidate loci putatively under selection by temperature and precipitation. We found that C. fargesii populations possessed high genetic diversity and moderate differentiation among them, indicating predominant outcrossing and few restrictions to gene flow. These patterns reduce the possible impact of stochastic effects or the influence of genetic isolation. Clear footprints of divergent selection at four loci were discovered. Frequencies of five alleles at these loci were strongly correlated with environmental factors, particularly extremes in precipitation. These alleles varied from being near fixation at one end of the gradient to being completely absent at the other. Our study species is an important forest tree in the subtropical regions of China and could have a major role in future management and reforestation plans. Our results demonstrate that the gene flow is widespread and abundant in natural populations, maintaining high diversity, while diversifying selection is acting on specific genomic regions. PMID:24984608

  9. Natural selection for the Duffy-null allele in the recently admixed people of Madagascar

    PubMed Central

    Hodgson, Jason A.; Pickrell, Joseph K.; Pearson, Laurel N.; Quillen, Ellen E.; Prista, António; Rocha, Jorge; Soodyall, Himla; Shriver, Mark D.; Perry, George H.

    2014-01-01

    While gene flow between distantly related populations is increasingly recognized as a potentially important source of adaptive genetic variation for humans, fully characterized examples are rare. In addition, the role that natural selection for resistance to vivax malaria may have played in the extreme distribution of the protective Duffy-null allele, which is nearly completely fixed in mainland sub-Saharan Africa and absent elsewhere, is controversial. We address both these issues by investigating the evolution of the Duffy-null allele in the Malagasy, a recently admixed population with major ancestry components from both East Asia and mainland sub-Saharan Africa. We used genome-wide genetic data and extensive computer simulations to show that the high frequency of the Duffy-null allele in Madagascar can only be explained in the absence of positive natural selection under extreme demographic scenarios involving high genetic drift. However, the observed genomic single nucleotide polymorphism diversity in the Malagasy is incompatible with such extreme demographic scenarios, indicating that positive selection for the Duffy-null allele best explains the high frequency of the allele in Madagascar. We estimate the selection coefficient to be 0.066. Because vivax malaria is endemic to Madagascar, this result supports the hypothesis that malaria resistance drove fixation of the Duffy-null allele in mainland sub-Saharan Africa. PMID:24990677

  10. Unusual selection on the KIR3DL1/S1 natural killer cell receptor in Africans.

    PubMed

    Norman, Paul J; Abi-Rached, Laurent; Gendzekhadze, Ketevan; Korbel, Daniel; Gleimer, Michael; Rowley, Don; Bruno, Dan; Carrington, Christine V F; Chandanayingyong, Dasdayanee; Chang, Yih-Hsin; Crespí, Catalina; Saruhan-Direskeneli, Güher; Fraser, Patricia A; Hameed, Kamran; Kamkamidze, Giorgi; Koram, Kwadwo A; Layrisse, Zulay; Matamoros, Nuria; Milà, Joan; Park, Myoung Hee; Pitchappan, Ramasamy M; Ramdath, D Dan; Shiau, Ming-Yuh; Stephens, Henry A F; Struik, Siske; Verity, David H; Vaughan, Robert W; Tyan, Dolly; Davis, Ronald W; Riley, Eleanor M; Ronaghi, Mostafa; Parham, Peter

    2007-09-01

    Interactions of killer cell immunoglobulin-like receptors (KIRs) with major histocompatibility complex (MHC) class I ligands diversify natural killer cell responses to infection. By analyzing sequence variation in diverse human populations, we show that the KIR3DL1/S1 locus encodes two lineages of polymorphic inhibitory KIR3DL1 allotypes that recognize Bw4 epitopes of protein">HLA-A and HLA-B and one lineage of conserved activating KIR3DS1 allotypes, also implicated in Bw4 recognition. Balancing selection has maintained these three lineages for over 3 million years. Variation was selected at D1 and D2 domain residues that contact HLA class I and at two sites on D0, the domain that enhances the binding of KIR3D to HLA class I. HLA-B variants that gained Bw4 through interallelic microconversion are also products of selection. A worldwide comparison uncovers unusual KIR3DL1/S1 evolution in modern sub-Saharan Africans. Balancing selection is weak and confined to D0, KIR3DS1 is rare and KIR3DL1 allotypes with similar binding sites predominate. Natural killer cells express the dominant KIR3DL1 at a high frequency and with high surface density, providing strong responses to cells perturbed in Bw4 expression. PMID:17694054

  11. Experimental evolution can unravel the complex causes of natural selection in clinical infections.

    PubMed

    Brockhurst, Michael A

    2015-06-01

    It is increasingly clear that rapid evolutionary dynamics are an important process in microbial ecology. Experimental evolution, wherein microbial evolution is observed in real-time, has revealed many instances of appreciable evolutionary change occurring on very short timescales of a few days or weeks in response to a variety of biotic and abiotic selection pressures. From clinical infections, including the chronic bacterial lung infections associated with cystic fibrosis that form a focus of my research, there is now abundant evidence suggesting that rapid evolution by infecting microbes contributes to host adaptation, treatment failure and worsening patient prognosis. However, disentangling the drivers of natural selection in complex infection environments is extremely challenging and limits our understanding of the selective pressures acting upon microbes in infections. Controlled evolution experiments can make a vital contribution to this by determining the causal links between predicted drivers of natural selection and the evolutionary responses of microbes. Integration of experimental evolution into studies of clinical infections is a key next step towards a better understanding of the causes and consequences of rapid microbial evolution in infections, and discovering how these evolutionary processes might be influenced to improve patient health.A video of this Prize Lecture, presented at the Society for General Microbiology Annual Conference 2015, can be viewed via this link: Michael A. Brockhurst https://www.youtube.com/watch?v=N1bodVSl27E. PMID:25957311

  12. Footprints of divergent selection in natural populations of Castanopsis fargesii (Fagaceae).

    PubMed

    Li, C; Sun, Y; Huang, H W; Cannon, C H

    2014-12-01

    Given predicted rapid climate change, an understanding of how environmental factors affect genetic diversity in natural populations is important. Future selection pressures are inherently unpredictable, so forest management policies should maintain both overall diversity and identify genetic markers associated with the environmental factors expected to change most rapidly, like temperature and rainfall. In this study, we genotyped 648 individuals in 28 populations of Castanopsis fargesii (Fagaceae) using 32 expressed sequence tag (EST)-derived microsatellite markers. After removing six loci that departed from Hardy-Weinberg equilibrium, we measured genetic variation, population structure and identified candidate loci putatively under selection by temperature and precipitation. We found that C. fargesii populations possessed high genetic diversity and moderate differentiation among them, indicating predominant outcrossing and few restrictions to gene flow. These patterns reduce the possible impact of stochastic effects or the influence of genetic isolation. Clear footprints of divergent selection at four loci were discovered. Frequencies of five alleles at these loci were strongly correlated with environmental factors, particularly extremes in precipitation. These alleles varied from being near fixation at one end of the gradient to being completely absent at the other. Our study species is an important forest tree in the subtropical regions of China and could have a major role in future management and reforestation plans. Our results demonstrate that the gene flow is widespread and abundant in natural populations, maintaining high diversity, while diversifying selection is acting on specific genomic regions. PMID:24984608

  13. Inference of Episodic Changes in Natural Selection Acting on Protein Coding Sequences via CODEML.

    PubMed

    Bielawski, Joseph P; Baker, Jennifer L; Mingrone, Joseph

    2016-01-01

    This unit provides protocols for using the CODEML program from the PAML package to make inferences about episodic natural selection in protein-coding sequences. The protocols cover inference tasks such as maximum likelihood estimation of selection intensity, testing the hypothesis of episodic positive selection, and identifying sites with a history of episodic evolution. We provide protocols for using the rich set of models implemented in CODEML to assess robustness, and for using bootstrapping to assess if the requirements for reliable statistical inference have been met. An example dataset is used to illustrate how the protocols are used with real protein-coding sequences. The workflow of this design, through automation, is readily extendable to a larger-scale evolutionary survey. © 2016 by John Wiley & Sons, Inc. PMID:27322407

  14. Herbaceous plant species invading natural areas tend to have stronger adaptive root foraging than other naturalized species.

    PubMed

    Keser, Lidewij H; Visser, Eric J W; Dawson, Wayne; Song, Yao-Bin; Yu, Fei-Hai; Fischer, Markus; Dong, Ming; van Kleunen, Mark

    2015-01-01

    Although plastic root-foraging responses are thought to be adaptive, as they may optimize nutrient capture of plants, this has rarely been tested. We investigated whether nutrient-foraging responses are adaptive, and whether they pre-adapt alien species to become natural-area invaders. We grew 12 pairs of congeneric species (i.e., 24 species) native to Europe in heterogeneous and homogeneous nutrient environments, and compared their foraging responses and performance. One species in each pair is a USA natural-area invader, and the other one is not. Within species, individuals with strong foraging responses, measured as plasticity in root diameter and specific root length, had a higher biomass. Among species, the ones with strong foraging responses, measured as plasticity in root length and root biomass, had a higher biomass. Our results therefore suggest that root foraging is an adaptive trait. Invasive species showed significantly stronger root-foraging responses than non-invasive species when measured as root diameter. Biomass accumulation was decreased in the heterogeneous vs. the homogeneous environment. In aboveground, but not belowground and total biomass, this decrease was smaller in invasive than in non-invasive species. Our results show that strong plastic root-foraging responses are adaptive, and suggest that it might aid in pre-adapting species to becoming natural-area invaders. PMID:25964790

  15. Herbaceous plant species invading natural areas tend to have stronger adaptive root foraging than other naturalized species

    PubMed Central

    Keser, Lidewij H.; Visser, Eric J. W.; Dawson, Wayne; Song, Yao-Bin; Yu, Fei-Hai; Fischer, Markus; Dong, Ming; van Kleunen, Mark

    2015-01-01

    Although plastic root-foraging responses are thought to be adaptive, as they may optimize nutrient capture of plants, this has rarely been tested. We investigated whether nutrient-foraging responses are adaptive, and whether they pre-adapt alien species to become natural-area invaders. We grew 12 pairs of congeneric species (i.e., 24 species) native to Europe in heterogeneous and homogeneous nutrient environments, and compared their foraging responses and performance. One species in each pair is a USA natural-area invader, and the other one is not. Within species, individuals with strong foraging responses, measured as plasticity in root diameter and specific root length, had a higher biomass. Among species, the ones with strong foraging responses, measured as plasticity in root length and root biomass, had a higher biomass. Our results therefore suggest that root foraging is an adaptive trait. Invasive species showed significantly stronger root-foraging responses than non-invasive species when measured as root diameter. Biomass accumulation was decreased in the heterogeneous vs. the homogeneous environment. In aboveground, but not belowground and total biomass, this decrease was smaller in invasive than in non-invasive species. Our results show that strong plastic root-foraging responses are adaptive, and suggest that it might aid in pre-adapting species to becoming natural-area invaders. PMID:25964790

  16. [Production of plant-derived natural products in yeast cells - A review].

    PubMed

    Wang, Dong; Dai, Zhubo; Zhang, Xueli

    2016-03-01

    Plant-derived natural products (PNPs) have been widely used in pharmaceutical and nutritional fields. So far, the main method to produce PNPs is extracting them from their original plants, however, there remains lots of problems. With the concept of synthetic biology, construction of yeast cell factories for production of PNPs provides an alternative way. In this review, we will focus on PNPs' market and application, research progress for production of artemisinin, research progress for production of terpenes, alkaloids and polyunsaturated fatty acid (PUFAs) and recent technology development to give a brief introduction of construction of yeast cells for production of PNPs. PMID:27382793

  17. Natural Circulation in Water Cooled Nuclear Power Plants Phenomena, models, and methodology for system reliability assessments

    SciTech Connect

    Jose Reyes

    2005-02-14

    In recent years it has been recognized that the application of passive safety systems (i.e., those whose operation takes advantage of natural forces such as convection and gravity), can contribute to simplification and potentially to improved economics of new nuclear power plant designs. In 1991 the IAEA Conference on ''The Safety of Nuclear Power: Strategy for the Future'' noted that for new plants the use of passive safety features is a desirable method of achieving simplification and increasing the reliability of the performance of essential safety functions, and should be used wherever appropriate''.

  18. Screening of selected ethnomedicinal plants from South Africa for larvicidal activity against the mosquito Anopheles arabiensis

    PubMed Central

    2012-01-01

    Background This study was initiated to establish whether any South African ethnomedicinal plants (indigenous or exotic), that have been reported to be used traditionally to repel or kill mosquitoes, exhibit effective mosquito larvicidal properties. Methods Extracts of a selection of plant taxa sourced in South Africa were tested for larvicidal properties in an applicable assay. Thirty 3rd instar Anopheles arabiensis larvae were exposed to various extract types (dichloromethane, dichloromethane/methanol) (1:1), methanol and purified water) of each species investigated. Mortality was evaluated relative to the positive control Temephos (Mostop; Agrivo), an effective emulsifiable concentrate larvicide. Results Preliminary screening of crude extracts revealed substantial variation in toxicity with 24 of the 381 samples displaying 100% larval mortality within the seven day exposure period. Four of the high activity plants were selected and subjected to bioassay guided fractionation. The results of the testing of the fractions generated identified one fraction of the plant, Toddalia asiatica as being very potent against the An. arabiensis larvae. Conclusion The present study has successfully identified a plant with superior larvicidal activity at both the crude and semi pure fractions generated through bio-assay guided fractionation. These results have initiated further research into isolating the active compound and developing a malaria vector control tool. PMID:22963538

  19. Selecting and evaluating native plants for region-specific phytotoxicity testing.

    PubMed

    Olszyk, David; Pfleeger, Thomas; Lee, E Henry; Burdick, Connie; King, George; Plocher, Milton; Kern, Jeffrey

    2008-01-01

    In this study, we evaluated methodology to determine risks to terrestrial native plant species from potential herbecide drift, focusing on 1) selection of native species for testing, 2) growth of these species, and 3) variability in herbicide response among native species and compared with crop plants. Native plant species were selected for initial testing on the basis of spatial analysis, which indicated that species from Illinois, USA, were at potential risk for off-target effects of herbicide drift. On the basis of preliminary seed germination tests, 5 native plant species (Andropogon gerardi, Polygonum lapathifolium, Solidago canadensis, Symphyotrichum lateriflorum, and Tridens flavus) were selected for comparison with crops grown in Illinois, normally used in the US Environmental Protection Agency's (USEPA's) Vegetative Vigor Test (Avena sativa, Daucus carota, Glycine max, Solanum lycopersicon, and Zea mays), or both. When treated with low concentrations of a test herbicide, sulfometuron methyl, 2 native species, P. lapathifolium and S. canadensis, were as sensitive as the 5 crop species. The effective herbicide concentrations producing a 25% reduction in shoot dry weight (EC25) for these species, ranged from 0.00015 to 0.0014 times a field application concentration of 52 g/ha active ingredient of sulfometuron methyl. S. lateriflorum and T. flavus were less sensitive than the other native species, whereas A. gerardi was tolerant to sulfometuron methyl with no growth reduction at any herbicide concentration tested. This study indicated that native species can be successfully selected and grown, used in the suite of species used in the USEPA's phytotoxicity test to assess risks of chemical herbicides to nontarget plants. It also showed (with a limited number of species) that native species varied more in sensitivity to simulated herbicide drift than crop species often used in phytotoxicity testing and that a Weibull function was useful to calculate EC25 values

  20. Host Range and Selectivity of the Hemiparasitic Plant Thesium chinense (Santalaceae)

    PubMed Central

    Suetsugu, Kenji; Kawakita, Atsushi; Kato, Makoto

    2008-01-01

    Background and Aims Thesium chinense is a hemiparasitic plant that is common in grassland habitats of eastern Asia. Although the physiology of Thesium has been well studied in attempts to control its weedy habit, there have been few ecological investigations of its parasitic life history. Thesium chinense is thought to parasitize species of Poaceae, but evidence remains circumstantial. Methods A vegetation survey was conducted to test whether any plant species occurs significantly more often in plots with T. chinense than expected. In addition, haustorial connections were examined directly by excavating the roots and post-attachment host selectivity was evaluated by comparing the observed numbers of haustoria on different hosts against those expected according to the relative below-ground biomass. Haustorium sizes were also compared among host species. Key Results Only two of the 38 species recorded, Lespedeza juncea and Eragrostis curvula, occurred more often in plots with Thesium than expected. In contrast to this, T. chinense parasitized 22 plant species in 11 families, corresponding to 57·9 % of plant species found at the study site. Haustoria were non-randomly distributed among host species, suggesting that there is some post-attachment host selectivity. Thesium chinense generally preferred the Poaceae, although haustoria formed on the Fabaceae were larger than those on other hosts. Conclusions This is the first quantitative investigation of the host range and selectivity of hemiparasitic plants of the Santalales. The preference for Fabaceae as hosts may be linked to the greater nutrient availability in these nitrogen-fixing plants. PMID:18492736