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1

Photoperiodic regulation of nuclear melatonin receptor ROR? in lymphoid organs of a tropical rodent Funambulus pennanti: role in seasonal oxidative stress.  

PubMed

The orphan nuclear receptor ROR? of RZR/ROR family has been suggested to mediate the genomic actions of melatonin on the expression of antioxidant enzymes. However, no direct evidences exist. In the present study we explored the role of photoperiod (natural and artificial) in regulation of ROR? and its association with the photoperiod induced antioxidant defense system in the lymphoid organs (spleen and thymus) of seasonally breeding, tropical squirrels, Funambulus pennanti. The photoperiod mediated regulation of antioxidant status was checked along with the ROR? expression and circulatory melatonin level in the squirrels. The enhancement of the antioxidant capacity of serum and lymphoid organ was concomitant with the short photoperiod (10L:14D) induced high levels of plasma melatonin. Further, peripheral melatonin level enhanced the AANAT activity as well as the melatonin synthesis in the lymphoid tissues. ROR? expression presented an inverse correlation with the plasma level of melatonin as well as the short day induced antioxidant enzyme activity in the lymphoid organs. The results suggest that for reduction of seasonal oxidative stress melatonin might not be utilizing the nuclear receptor ROR? pathway; rather the rise in circulatory melatonin collectively with tissue specific melatonin might be protecting the splenic and thymic lymphocytes from the seasonal oxidative stress. PMID:25541021

Gupta, Sameer; Haldar, Chandana; Ahmad, Raise

2015-01-01

2

Phase and period responses to short light pulses in a wild diurnal rodent, Funambulus pennanti.  

PubMed

Photic phase response curves (PRCs) have been extensively studied in many laboratory-bred diurnal and nocturnal rodents. However, comparatively fewer studies have addressed the effects of photic cues on wild diurnal mammals. Hence, we studied the effects of short durations of light pulses on the circadian systems of the diurnal Indian Palm squirrel, Funambulus pennanti. Adult males entrained to a light-dark cycle (12 h-12?h) were transferred to constant darkness (DD). Free-running animals were exposed to brief light pulses (250 lux) of 15 min, 3 circadian hours (CT) apart (CT 0, 3, 6, 9, 12, 15, 18 and 21). Phase shifts evoked at different phases were plotted against CT and a PRC was constructed. F. pennanti exhibited phase-dependent phase shifts at all the CTs studied, and the PRC obtained was of type 1 at the intensity of light used. Phase advances were evoked during the early subjective day and late subjective night, while phase delays occurred during the late subjective day and early subjective night, with maximum phase delay at CT 15 (-2.04 ± 0.23 h), and maximum phase advance at CT 21 (1.88 ± 0.31 h). No dead zone was seen at this resolution. The free-running period of the rhythm was concurrently lengthened (deceleration) during the late subjective day and early subjective night, while period shortening (acceleration) occurred during the late subjective night. The maximum deceleration was noticed at CT 15 (-0.40 ± 0.09 h) and the maximum acceleration at CT 21 (0.39 ± 0.07 h). A significant positive correlation exists between the phase shifts and the period changes (r = 0.684, p = 0.001). The shapes of both the PRC and period response curve (?RC) qualitatively resemble each other. This suggests that the palm squirrel's circadian system is entrained both by phase and period responses to light. Thus, F. pennanti exhibits robust clock-resetting in response to light pulses. PMID:24180638

Kumar, Dhanananajay; Singaravel, Muniyandi

2014-04-01

3

Effect of lead nitrate on thyroid function on the Indian palm squirrel, Funambulus pennanti (Wroughton)  

SciTech Connect

Some of the known toxic effects of lead in mammals including man are, impaired heme synthesis, anemia, nepatopathy, nephropathy, behavioral disorders and neuropathy. However, very little is known about the effect of lead on endocrine physiology. Some data are available on lead induced impairment of thyroid function in occupationally exposed men and experimental rats. As lead nitrate is largely consumed through water and food, in this study the wild rodents Funambulus pennanti were administered lead through their drinking water and their thyroid structure, radioiodine 131-I percentage uptake and protein bound iodine (PBI) level were assessed.

Shrivastava, V.K.; Katti, S.R.; Sathyanesan, A.G.

1987-06-01

4

Ancient DNA and the tropics: a rodent's tale.  

PubMed

Most genetic studies of Holocene fauna have been performed with ancient samples from dry and cold regions, in which preservation of fossils is facilitated and molecular damage is reduced. Ancient DNA work from tropical regions has been precluded owing to factors that limit DNA preservation (e.g. temperature, hydrolytic damage). We analysed ancient DNA from rodent jawbones identified as Ototylomys phyllotis, found in Holocene and Late Pleistocene stratigraphic layers from Loltún, a humid tropical cave located in the Yucatan peninsula. We extracted DNA and amplified six short overlapping fragments of the cytochrome b gene, totalling 666 bp, which represents an unprecedented success considering tropical ancient DNA samples. We performed genetic, phylogenetic and divergence time analyses, combining sequences from ancient and modern O. phyllotis, in order to assess the ancestry of the Loltún samples. Results show that all ancient samples fall into a unique clade that diverged prior to the divergence of the modern O. phyllotis, supporting it as a distinct Pleistocene form of the Ototylomys genus. Hence, this rodent's tale suggests that the sister group to modern O. phyllotis arose during the Miocene-Pliocene, diversified during the Pleistocene and went extinct in the Holocene. PMID:24899682

Gutiérrez-García, Tania A; Vázquez-Domínguez, Ella; Arroyo-Cabrales, Joaquín; Kuch, Melanie; Enk, Jacob; King, Christine; Poinar, Hendrik N

2014-06-01

5

Museum specimen data predict crop damage by tropical rodents  

PubMed Central

Museum collections constitute a massive store of information on biological diversity. We used museum specimen data to generate ecological niche models that provide predictions of geographic distributions of native rodent pest species and agricultural census data that summarize the geographic distribution of nine crops in the state of Veracruz, Mexico, as well as crop losses between planting and harvest. Herein, we show that crop damage is related significantly to the predicted presence of rodent species for seven of nine crops. Museum collections may thus provide important baseline information for designing land-use and agricultural pest-management programs. PMID:10860973

Sánchez-Cordero, Víctor; Martínez-Meyer, Enrique

2000-01-01

6

Effect of logging on rodent scatter-hoarding dynamics in tropical forests: implications for plant recruitment.  

PubMed

The present study tested the hypothesis that logging affects the scatter-hoarding behavior of rodents, which, in turn, negatively affects the quantity and quality of Pouteria campechiana (Sapotaceae) seed dispersal. A series of seed stations was established in logged and unlogged forests of ejido Señor, Yucatan Peninsula, and comparisons were made between logged and unlogged forests in terms of: (i) seed removal; (ii) number of seeds hoarded; (iii) hoarding distance; and (iv) the number of recruits and the survival of hoarded seeds. The number of both hoarded and removed seeds was significantly higher in unlogged sites. Furthermore, the mean distance of hoarding was greater in unlogged compared with logged sites. Although recruitment and survival were present in both logged and unlogged sites, there were more surviving seedlings in unlogged sites. The data indicate that both the quantity and quality of seed dispersal are negatively affected by logging because of a change in the rodent scatter-hoarding dynamics. These changes suggest that plant-animal interactions are crucial to the understanding of the ecology and conservation of managed tropical forests. PMID:21645273

Gutiérrez-Granados, Gabriel

2011-06-01

7

Long-term melatonin administration attenuates low-LET ?-radiation-induced lymphatic tissue injury during the reproductively active and inactive phases of Indian palm squirrels (Funambulus pennanti)  

PubMed Central

A comparative analysis of low linear energy transfer (LET) ?-radiation-induced damage in the lymphatic tissue of a tropical seasonal breeder, Indian palm squirrel (Funambulus pennanti), during its reproductively active phase (RAP) and inactive phase (RIP) was performed with simultaneous investigation of the effects of long-term melatonin pre-treatment (100 ?g/100 g body weight). A total of 120 squirrels (60 during RAP and 60 during RIP) were divided into 12 groups and sacrificed at 4, 24, 48, 72 and 168 h following 5 Gy ?-radiation exposure; control groups were excluded from exposure. Total leukocyte count and absolute lymphocyte count (ALC) and melatonin only of peripheral blood, stimulation index, thiobarbituric-acid-reactive substances (TBARS) level, superoxide dismutase (SOD) activity, and the apoptotic index of spleen as analysed by terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end labelling (TUNEL) noted at observed time-points were significantly reduced in melatonin pre-treated groups during RAP and RIP. Long-term melatonin pre-treatment mitigated radiation-induced alterations more prominently during RIP, as assessed by ALC, TBARS, SOD, TUNEL and caspase-3 activity, at some time-points. Our results demonstrate an inhibitory role of melatonin on caspase-3 activity in splenocytes during RAP and RIP following ?-radiation-induced caspase-mediated apoptosis. Hence, we propose that melatonin might preserve the viability of immune cells of a seasonal breeder against background radiation, which is constantly present in the environment. PMID:20139262

Sharma, S; Haldar, C; Chaube, S K; Laxmi, T; Singh, S S

2010-01-01

8

Rodent seed predation: effects on seed survival, recruitment, abundance, and dispersion of bird-dispersed tropical trees.  

PubMed

Tropical tree species vary widely in their pattern of spatial dispersion. We focus on how seed predation may modify seed deposition patterns and affect the abundance and dispersion of adult trees in a tropical forest in India. Using plots across a range of seed densities, we examined whether seed predation levels by terrestrial rodents varied across six large-seeded, bird-dispersed tree species. Since inter-specific variation in density-dependent seed mortality may have downstream effects on recruitment and adult tree stages, we determined recruitment patterns close to and away from parent trees, along with adult tree abundance and dispersion patterns. Four species (Canarium resiniferum, Dysoxylum binectariferum, Horsfieldia kingii, and Prunus ceylanica) showed high predation levels (78.5-98.7%) and increased mortality with increasing seed density, while two species, Chisocheton cumingianus and Polyalthia simiarum, showed significantly lower seed predation levels and weak density-dependent mortality. The latter two species also had the highest recruitment near parent trees, with most abundant and aggregated adults. The four species that had high seed mortality had low recruitment under parent trees, were rare, and had more spaced adult tree dispersion. Biotic dispersal may be vital for species that suffer density-dependent mortality factors under parent trees. In tropical forests where large vertebrate seed dispersers but not seed predators are hunted, differences in seed vulnerability to rodent seed predation and density-dependent mortality can affect forest structure and composition. PMID:22327614

Velho, Nandini; Isvaran, Kavita; Datta, Aparajita

2012-08-01

9

Rodent Diversity in a Highly Degraded Tropical Landscape: Hong Kong, South China  

Microsoft Academic Search

The diverse ecological roles played by different rodent species mean that the loss of some species and superabundance of others\\u000a could potentially influence a wide range of ecological processes. Hong Kong (22° N, 114° E), with seven million people in\\u000a a land area of 1100 km2, could be considered a `worst case scenario' for the survival of mammalian diversity. Existing information on rodents

Kylie P. S. Chung; Richard T. Corlett

2006-01-01

10

Seed traits and taxonomic relationships determine the occurrence of mutualisms versus seed predation in a tropical forest rodent and seed dispersal system.  

PubMed

Although many studies have been carried out on plant-animal mutualistic assemblages, the roles of functional traits and taxonomy in determining both whether interactions involve mutualisms or predation and the structure of such assemblages are unclear. We used semi-natural enclosures to quantitatively assess the interaction strengths between seeds of 8 sympatric tree species and 4 rodent species in a tropical forest in Xishuangbanna, Yunnan, Southwest China. We found 2 clusters of species in the seed-rodent network represented by 2 genera in the Fagaceae (Castanopsis, Lithocarpus). Compared to seeds of 3 Castanopsis species, seeds with heavy weight, hard coat or caloric content (including 3 Lithocarpus species) were eaten less and more frequently hoarded by rodents. In turn, hoarded seeds showed less predation and more mutualism with rodents. Our results suggest that seed traits significantly affected the hoarding behavior of rodents, and, consequently, the occurrence of mutualisms and predation as well as assemblage structure in the plant-animal seed dispersal system. Taxonomically-related species with similar seed traits as functional groups belong to the same substructures in the assemblage. Our results indicate that both seed traits and taxonomic relationships may simplify thinking about seed dispersal systems by helping to elucidate whether interactions are likely to be dominated by predation or mutualism. PMID:24382317

Wang, Zhenyu; Cao, Lin; Zhang, Zhibin

2014-06-01

11

Scatter-hoarding rodents as secondary seed dispersers of a frugivore-dispersed tree Scleropyrum wallichianum in a defaunated Xishuangbanna tropical forest, China.  

PubMed

Local extinction or population decline of large frugivorous vertebrates as primary seed dispersers, caused by human disturbance and habitat change, might lead to dispersal limitation of many large-seeded fruit trees. However, it is not known whether or not scatter-hoarding rodents as secondary seed dispersers can help maintain natural regeneration (e.g. seed dispersal) of these frugivore-dispersed trees in the face of the functional reduction or loss of primary seed dispersers. In the present study, we investigated how scatter-hoarding rodents affect the fate of tagged seeds of a large-seeded fruit tree (Scleropyrum wallichianum Arnott, 1838, Santalaceae) from seed fall to seedling establishment in a heavily defaunated tropical forest in the Xishuangbanna region of Yunnan Province, in southwest China, in 2007 and 2008. Our results show that: (i) rodents removed nearly all S. wallichianum seeds in both years; (ii) a large proportion (2007, 75%; 2008, 67.5%) of the tagged seeds were cached individually in the surface soil or under leaf litters; (iii) dispersal distance of primary caches was further in 2007 (19.6 ± 14.6 m) than that in 2008 (14.1 ± 11.6 m), and distance increased as rodents recovered and moved seeds from primary caches into subsequent caching sites; and (iv) part of the cached seeds (2007, 3.2%; 2008, 2%) survived to the seedling stage each year. Our study suggests that by taking roles of both primary and secondary seed dispersers, scatter-hoarding rodents can play a significant role in maintaining seedling establishment of S. wallichianum, and are able to at least partly compensate for the loss of large frugivorous vertebrates in seed dispersal. PMID:21910842

Cao, Lin; Xiao, Zhishu; Guo, Cong; Chen, Jin

2011-09-01

12

Rodent Research-1 Validation of Rodent Hardware  

NASA Technical Reports Server (NTRS)

To achieve novel science objectives, validation of a rodent habitat on ISS will enable - In-flight analyses during long duration spaceflight- Use of genetically altered animals- Application of modern analytical techniques (e.g. genomics, proteomics, and metabolomics)

Globus, Ruth; Beegle, Janet

2013-01-01

13

The largest fossil rodent  

PubMed Central

The discovery of an exceptionally well-preserved skull permits the description of the new South American fossil species of the rodent, Josephoartigasia monesi sp. nov. (family: Dinomyidae; Rodentia: Hystricognathi: Caviomorpha). This species with estimated body mass of nearly 1000?kg is the largest yet recorded. The skull sheds new light on the anatomy of the extinct giant rodents of the Dinomyidae, which are known mostly from isolated teeth and incomplete mandible remains. The fossil derives from San José Formation, Uruguay, usually assigned to the Pliocene–Pleistocene (4–2?Myr ago), and the proposed palaeoenvironment where this rodent lived was characterized as an estuarine or deltaic system with forest communities. PMID:18198140

Rinderknecht, Andrés; Blanco, R. Ernesto

2008-01-01

14

Rodent Control in India  

Microsoft Academic Search

Eighteen species of rodents are pests in agriculture, horticulture, forestry, animal and human dwellings and rural and urban storage facilities in India. Their habitat, distribution, abundance and economic significance varies in different crops, seasons and geographical regions of the country. Of these, Bandicota bengalensis is the most predominant and widespread pest of agriculture in wet and irrigated soils and has

V. R. Parshad

1999-01-01

15

Thieving rodents as substitute dispersers of megafaunal seeds  

PubMed Central

The Neotropics have many plant species that seem to be adapted for seed dispersal by megafauna that went extinct in the late Pleistocene. Given the crucial importance of seed dispersal for plant persistence, it remains a mystery how these plants have survived more than 10,000 y without their mutualist dispersers. Here we present support for the hypothesis that secondary seed dispersal by scatter-hoarding rodents has facilitated the persistence of these large-seeded species. We used miniature radio transmitters to track the dispersal of reputedly megafaunal seeds by Central American agoutis, which scatter-hoard seeds in shallow caches in the soil throughout the forest. We found that seeds were initially cached at mostly short distances and then quickly dug up again. However, rather than eating the recovered seeds, agoutis continued to move and recache the seeds, up to 36 times. Agoutis dispersed an estimated 35% of seeds for >100 m. An estimated 14% of the cached seeds survived to the next year, when a new fruit crop became available to the rodents. Serial video-monitoring of cached seeds revealed that the stepwise dispersal was caused by agoutis repeatedly stealing and recaching each other’s buried seeds. Although previous studies suggest that rodents are poor dispersers, we demonstrate that communities of rodents can in fact provide highly effective long-distance seed dispersal. Our findings suggest that thieving scatter-hoarding rodents could substitute for extinct megafaunal seed dispersers of tropical large-seeded trees. PMID:22802644

Jansen, Patrick A.; Hirsch, Ben T.; Emsens, Willem-Jan; Zamora-Gutierrez, Veronica; Wikelski, Martin; Kays, Roland

2012-01-01

16

Toxoplasmosis seroprevalence in urban rodents: a survey in Niamey, Niger  

PubMed Central

A serological survey of Toxoplasma gondii was conducted on 766 domestic and peridomestic rodents from 46 trapping sites throughout the city of Niamey, Niger. A low seroprevalence was found over the whole town with only 1.96% of the rodents found seropositive. However, differences between species were important, ranging from less than 2% in truly commensal Mastomys natalensis, Rattus rattus and Mus musculus, while garden-associated Arvicanthis niloticus displayed 9.1% of seropositive individuals. This is in line with previous studies on tropical rodents - that we reviewed here - which altogether show that Toxoplasma seroprevalence in rodent is highly variable, depending on many factors such as locality and/or species. Moreover, although we were not able to decipher statistically between habitat or species effect, such a contrast between Nile grass rats and the other rodent species points towards a potentially important role of environmental toxoplasmic infection. This would deserve to be further scrutinised since intra-city irrigated cultures are extending in Niamey, thus potentially increasing Toxoplasma circulation in this yet semi-arid region. As far as we are aware of, our study is one of the rare surveys of its kind performed in Sub-Saharan Africa and the first one ever conducted in the Sahel. PMID:23828008

Mercier, Aurélien; Garba, Madougou; Bonnabau, Henri; Kane, Mamadou; Rossi, Jean-Pierre; Dardé, Marie-Laure; Dobigny, Gauthier

2013-01-01

17

Geomagnetic field detection in rodents  

SciTech Connect

In addition to behavioral evidence for the detection of earth-strength magnetic fields (MF) by rodents, recent investigations have revealed that electrophysiological and biochemical responses to MF occur in the pineal organ and retina of rodents. In addition, ferrimagnetic deposits have been identified in the ethmoidal regions of the rodent skull. These findings point to a new sensory phenomenon, which interfaces with many fields of biology, including neuroscience, psychophysics, behavioral ecology, chronobiology and sensory physiology.

Olcese, J.; Reuss, S.; Semm, P.

1988-01-01

18

Lymphocytic Choriomeningitis Virus from Pet Rodents  

MedlinePLUS

... rodent? Rodents, such as mice, hamsters and guinea pigs, are popular as pets in many households. However, ... and pet mice, hamsters, and, on occasion, guinea pigs. What is LCMV? LCMV is carried by rodents ...

19

Tropical Belt  

NSDL National Science Digital Library

This lesson familiarizes learners with the term "tropical belt." First, learners locate the equator, Tropic of Cancer and Tropic of Capricorn on a map and trace these lines with a crayon. Learners also color in the locations of tropical rainforests. Next, learners cut along the colored lines of the Tropic of Cancer and Tropic of Capricorn. Educators can punch a hole at each end of this map and tie the ends together with yarn. Learners can wear the belt in class to remind themselves that rainforests are found near the equator or midsection of the Earth. This lesson includes extension ideas and is standards-based.

2012-06-26

20

Tropical Rainforests.  

ERIC Educational Resources Information Center

Presented is a summary of scientific knowledge about the rainforest environment, a tropical ecosystem in danger of extermination. Topics include the current state of tropical rainforests, the causes of rainforest destruction, and alternatives of rainforest destruction. (BT)

Nigh, Ronald B.; Nations, James D.

1980-01-01

21

Tropical malabsorption.  

PubMed

Malabsorption is an important clinical problem both in visitors to the tropics and in native residents of tropical countries. Infections of the small intestine are the most important cause of tropical malabsorption. Protozoal infections cause malabsorption in immunocompetent hosts, but do so more commonly in the setting of immune deficiency. Helminth infections occasionally cause malabsorption or protein-losing enteropathy. Intestinal tuberculosis, chronic pancreatitis and small-bowel bacterial overgrowth are important causes of tropical malabsorption. In recent years, inflammatory bowel disease and coeliac disease have become major causes of malabsorption in the tropics. Sporadic tropical sprue is still an important cause of malabsorption in adults and in children in South Asia. Investigations to exclude specific infective, immunological or inflammatory causes are important before considering tropical sprue as a diagnosis. This article briefly reviews the management of tropical sprue and presents an algorithm for its investigation and management. PMID:17148698

Ramakrishna, B S; Venkataraman, S; Mukhopadhya, A

2006-12-01

22

Rodent Abundance Dynamics and Leptospirosis Carriage in an Area of Hyper-Endemicity in New Caledonia  

PubMed Central

Background Widespread but particularly incident in the tropics, leptospirosis is transmitted to humans directly or indirectly by virtually any Mammal species. However, rodents are recognized as the most important reservoir. In endemic regions, seasonal outbreaks are observed during hot rainy periods. In such regions, hot spots can be evidenced, where leptospirosis is “hyper-endemic”, its incidence reaching 500 annual cases per 100,000. A better knowledge of how rodent populations and their Leptospira prevalence respond to seasonal and meteorological fluctuations might help implement relevant control measures. Methodology/Principal Findings In two tribes in New Caledonia with hyper-endemic leptospirosis, rodent abundance and Leptospira prevalence was studied twice a year, in hot and cool seasons for two consecutive years. Highly contrasted meteorological situations, particularly rainfall intensities, were noted between the two hot seasons studied. Our results show that during a hot and rainy period, both the rodent populations and their Leptospira carriage were higher. This pattern was more salient in commensal rodents than in the sylvatic rats. Conclusions/Significance The dynamics of rodents and their Leptospira carriage changed during the survey, probably under the influence of meteorology. Rodents were both more numerous and more frequently carrying (therefore disseminating) leptospires during a hot rainy period, also corresponding to a flooding period with higher risks of human exposure to waters and watered soils. The outbreaks of leptospirosis in hyper-endemic areas could arise from meteorological conditions leading to both an increased risk of exposure of humans and an increased volume of the rodent reservoir. Rodent control measures would therefore be most effective during cool and dry seasons, when rodent populations and leptospirosis incidence are low. PMID:22039557

Perez, Julie; Brescia, Fabrice; Becam, Jérôme; Mauron, Carine; Goarant, Cyrille

2011-01-01

23

The allometry of rodent intestines  

Microsoft Academic Search

This study examined the allometry of the small intestine, caecum, colon and large intestine of rodents (n = 51) using a phylogenetically informed approach. Strong phylogenetic signal was detected in the data for the caecum, colon\\u000a and large intestine, but not for the small intestine. Most of the phylogenetic signal could be attributed to clade effects\\u000a associated with herbivorous versus omnivorous rodents.

Barry G. Lovegrove

2010-01-01

24

Tropical myelopathies.  

PubMed

A large number of causal agents produce spinal cord lesions in the tropics. Most etiologies found in temperate regions also occur in the tropics including trauma, herniated discs, tumors, epidural abscess, and congenital malformations. However, infectious and nutritional disorders occur with higher prevalence in tropical regions. Among the most common infectious etiologies are tuberculous Pott's disease, brucellosis, and neuroborreliosis. Parasitic diseases such as schistosomiasis, neurocysticercosis, and eosinophilic meningitis are frequent causes of nontraumatic paraplegia. The retrovirus HTLV-1 is a cause of tropical spastic paraparesis. Nutritional causes of paraparesis include deficiencies of vitamin B12 and folate; endemic clusters of konzo and tropical ataxic myeloneuropathy are associated in Africa with malnutrition and excessive consumption of cyanide-containing bitter cassava. Other toxic etiologies of tropical paraplegia include lathyrism and fluorosis. Nutritional forms of myelopathy are associated often with optic and sensory neuropathy, hence the name tropical myeloneuropathies. Acute transverse myelopathy is seen in association with vaccination, infections, and fibrocartilaginous embolism of the nucleus pulposus. Multiple sclerosis and optic myelopathy occur in the tropics but with lesser prevalence than in temperate regions. The advent of modern imaging in the tropics, including computed tomography and magnetic resonance imaging, has allowed better diagnosis and treatment of these conditions that are a frequent cause of death and disability. PMID:24365434

Román, Gustavo C

2014-01-01

25

Probing perceptual decisions in rodents  

PubMed Central

The study of perceptual decision-making offers insight into how the brain uses complex, sometimes ambiguous information to guide actions. Understanding the underlying processes and their neural bases requires that one pair recordings and manipulations of neural activity with rigorous psychophysics. Though this research has been traditionally performed in primates, it seems increasingly promising to pursue it at least partly in mice and rats. However, rigorous psychophysical methods are not yet as developed for these rodents as they are for primates. Here we give a brief overview of the sensory capabilities of rodents and of their cortical areas devoted to sensation and decision. We then review methods of psychophysics, focusing on the technical issues that arise in their implementation in rodents. These methods represent a rich set of challenges and opportunities. PMID:23799475

Carandini, Matteo; Churchland, Anne K

2014-01-01

26

[Tropical sprue].  

PubMed

Tropical sprue associates prolonged diarrhea, a malabsorption syndrome, and nutritional deficiency in patients who live in or have visited tropical areas. Pathogenesis is still unknown but an infectious cause is suspected. Macrocytic anemia and hypoalbuminemia are present, together with progressive villus atrophy of the small intestine. Treatment with tetracycline, folic acid and proper nutritional support generally results in full recovery. PMID:17336033

Bourée, Patrice

2007-04-01

27

Tropical Sprue.  

PubMed

Tropical sprue is a disease that causes progressive villus atrophy in the small intestine, similar to nontropical (celiac) sprue. The loss of intestinal villi profoundly affects intestinal absorptive function, and patients with tropical or nontropical sprue present with malabsorption. Whereas the etiology of celiac sprue has been elucidated in considerable detail, the etiology of tropical sprue remains obscure. The favored hypothesis is that the disease is either initiated or sustained by a still-undefined infection. Patients with tropical sprue typically present with macrocytic anemia due to malabsorption of folate and/or vitamin B(12). Treatment of tropical sprue with folic acid replacement was introduced more than 50 years ago and has become standard medical treatment. Vitamin B(12) replacement is usually added if there is evidence of B(12) deficiency or malabsorption. Treatment of tropical sprue with folate and B(12) cures the macrocytic anemia and the accompanying glossitis, and often results in increased appetite and weight gain. However, even prolonged treatment with these vitamins fails to restore villus atrophy, and malabsorption usually persists. The benefit of antibiotic treatment of tropical sprue was first documented during World War II, when sulfonamides were used to treat epidemics of tropical sprue in British and Italian troops in India. Antibiotic treatment has since become the standard treatment, and tetracycline has replaced sulfonamides. The recommended length of treatment with tetracycline is 6 months and it is given in combination with folate. The treatment has been shown to normalize mucosal structure in the small intestine and resolve malabsorption in most patients with tropical sprue. However, there is a substantial relapse rate in treated patients who return to, or remain in, endemic areas in the tropics. PMID:14723833

Westergaard, Henrik

2004-02-01

28

Allometric disparity in rodent evolution  

PubMed Central

In this study, allometric trajectories for 51 rodent species, comprising equal representatives from each of the major clades (Ctenohystrica, Muroidea, Sciuridae), are compared in a multivariate morphospace (=allometric space) to quantify magnitudes of disparity in cranial growth. Variability in allometric trajectory patterns was compared to measures of adult disparity in each clade, and dietary habit among the examined species, which together encapsulated an ecomorphological breadth. Results indicate that the evolution of allometric trajectories in rodents is characterized by different features in sciurids compared with muroids and Ctenohystrica. Sciuridae was found to have a reduced magnitude of inter-trajectory change and growth patterns with less variation in allometric coefficient values among members. In contrast, a greater magnitude of difference between trajectories and an increased variation in allometric coefficient values was evident for both Ctenohystrica and muroids. Ctenohystrica and muroids achieved considerably higher adult disparities than sciurids, suggesting that conservatism in allometric trajectory modification may constrain morphological diversity in rodents. The results provide support for a role of ecology (dietary habit) in the evolution of allometric trajectories in rodents. PMID:23610638

Wilson, Laura A B

2013-01-01

29

Resistin in Rodents and Humans  

PubMed Central

Obesity is characterized by excess accumulation of lipids in adipose tissue and other organs, and chronic inflammation associated with insulin resistance and an increased risk of type 2 diabetes. Obesity, type 2 diabetes, and cardiovascular diseases are major health concerns. Resistin was first discovered as an adipose-secreted hormone (adipokine) linked to obesity and insulin resistance in rodents. Adipocyte-derived resistin is increased in obese rodents and strongly related to insulin resistance. However, in contrast to rodents, resistin is expressed and secreted from macrophages in humans and is increased in inflammatory conditions. Some studies have also suggested an association between increased resistin levels and insulin resistance, diabetes and cardiovascular disease. Genetic studies have provided additional evidence for a role of resistin in insulin resistance and inflammation. Resistin appears to mediate the pathogenesis of atherosclerosis by promoting endothelial dysfunction, vascular smooth muscle cell proliferation, arterial inflammation, and formation of foam cells. Indeed, resistin is predictive of atherosclerosis and poor clinical outcomes in patients with coronary artery disease and ischemic stroke. There is also growing evidence that elevated resistin is associated with the development of heart failure. This review will focus on the biology of resistin in rodents and humans, and evidence linking resistin with type 2 diabetes, atherosclerosis, and cardiovascular disease. PMID:24404511

Park, Hyeong Kyu

2013-01-01

30

Review: Population Fluctuations in Rodents  

E-print Network

Bats: Work- ing the Night Shift. By Greg Richards and Les Hall; principal photographer: Steve Parish. Collingwood (Australia): CSIRO Publish- ing. AU $79.95. viii #2; 184 p.; ill.; index. ISBN: 978-0-643-10374-0. 2012. The authors... interested in bats. Brock Fenton, Biology, University of Western On- tario, London, Ontario, Canada Population Fluctuations in Rodents. By Charles J. Krebs. Chicago (Illinois): University of Chicago Press. $55.00. x #2; 306 p.; ill.; index. ISBN: 978...

Armitage, Kenneth

2014-03-01

31

Tropical sprue.  

PubMed

Tropical sprue (TS) is a clinical entity of unknown etiology characterized by an acquired chronic diarrheal illness and malabsorption that affects indigenous inhabitants and expatriates, either long-term residents or short-term visitors, in the tropical countries. The exact pathogenetic sequence of TS remains incompletely characterized. Bacterial overgrowth, disturbed gut motility, and hormonal and histopathologic abnormalities contribute to the development of TS in a susceptible host. Treatment with tetracycline and folate is effective in some patients, although relapses after treatment are common. Research in the areas of microbial factors, pathogenesis, immunogenetics, and hormonal and immune regulation, using modern diagnostic techniques, may be able to settle some of the unanswered issues and open new venues for diagnosis, prevention, and treatment of tropical sprue. PMID:16168231

Nath, Samir Kumar

2005-10-01

32

Tropical malabsorption.  

PubMed

Tropical malabsorption remains an important clinical problem for both the indigenous population of tropical countries and for short-term visitors and longer-term residents from the industrialized world. In young children, persistent diarrhea and malabsorption can result in severe retardation of growth and development. The most common cause is an intestinal infection notably the small intestinal protozoa including Giardia intestinalis, Cryptosporidium parvum, Isospora belli, Cyclospora cayetanensis, and the microsporidia. Tropical sprue still remains an important diagnostic option but is less common than it was 20 to 30 years ago. It is important to attempt to make a specific microbiological diagnosis as this will influence the choice of antibiotic. However, if laboratory facilities are not available, it is possible to offer empirical therapy although this may involve a trial of more than one antibiotic. PMID:12465593

Farthing, Michael J G

2002-10-01

33

Mycobacteriosis in the rabbit and rodent.  

PubMed

Spontaneous mycobacteriosis is rare in rabbits and rodents with the exception of the pygmy rabbit, and there are only a handful of reported cases involving other rodents. Mycobacterium avium complex was the most commonly identified organism in reports of spontaneous mycobacteriosis involving rabbits and rodents. The resistance of rabbits and rodents to mycobacterial disease has been useful in understanding the disease in humans and other animals. Preventing or controlling Mycobacterium sp transmission from wildlife to domestic animals will require collaboration between agriculture, wildlife, environmental, and political entities. Understanding the ecology and epidemiology of mycobacteria is needed for better worldwide management of tuberculosis. PMID:22244115

McClure, Diane E

2012-01-01

34

Tropical Mathematics  

Microsoft Academic Search

These are the notes for the Clay Mathematics Institute Senior Scholar Lecture which was delivered by Bernd Sturmfels in Park City, Utah, on July 22, 2004. The topic of this lecture is the ``tropical approach'' in mathematics, which has gotten a lot of attention recently in combinatorics, algebraic geometry and related fields. It offers an an elementary introduction to this

David Speyer; Bernd Sturmfels

2004-01-01

35

Tropical Deforestation.  

ERIC Educational Resources Information Center

Outlines the deforestation problem and some efforts for solving the problem. Considers the impact of population growth, poverty, and ignorance. Includes a discussion of the current rapid decline in tropical forests, the consequences of destruction, and an outlook for the future. (YP)

Raven, Peter H.

1988-01-01

36

Urban resident attitudes toward rodents, rodent control products, and environmental effects  

EPA Science Inventory

Rodent control in urban areas can result in the inadvertent mortality of non-target species (e.g., bobcats). However, there is little detailed information about rodent control practices of urban residents. Our objective was to evaluate urban rodent control behaviors in two area...

37

Rodent Control: Seal Up! Trap Up! Clean Up!  

MedlinePLUS

... successfully trapping rodents in and around the home. Seal Up! Seal up holes inside and outside the home to ... infested areas. Before cleaning, trap the rodents and seal up any entryways to ensure that no rodents ...

38

Understanding arid environments using fossil rodent middens  

Microsoft Academic Search

American rodent middens have made a more dramatic contribution to understanding past environments and the development of ecological theory than Australian rodent middens. This relates to differences in the natural environment, the landscape histories, the scale and scientific approaches of the researchers. The comparison demonstrates: the power of synoptic perspectives; the value of thorough macrofossil identification in midden analysis and

Stuart Pearson; Julio L. Betancourtz

2002-01-01

39

Tropical Islands Jan Verschelde  

E-print Network

Tropical Rain Forest 5 Linear Algebra Jan Verschelde (UIC) Tropical Islands 16 January 2014 5 / 26 #12Tropical Islands Jan Verschelde University of Illinois at Chicago Department of Mathematics Algebraic Geometry Seminar Jan Verschelde (UIC) Tropical Islands 16 January 2014 1 / 26 #12;Tropical Islands

Verschelde, Jan

40

The Tropical Meteorology Project  

NSDL National Science Digital Library

This site includes a link to Tropical Storm Forecast, yearly forecasts for tropical storms, named storms, typhoons, hurricanes, and intense hurricanes include the current forecast and archived forecasts. Other links lead to weather products, research, and articles from The Tropical Meteorology Project, Colorado State University Researchers, and the Tropical Storm Research community from around the world. There are also tropical storm frequently asked questions about typhoons, hurricanes, and other types of tropical storms.

William Gray

2007-12-12

41

Embargoed African Rodents and Monkeypox Virus  

MedlinePLUS

... order also banned within the United States any sale, offering for distribution, transport, or release into the ... bans on importation of African rodents and the sale, distribution, transport, and release into the environment as ...

42

Guinea-zilla? World's largest rodent  

NSDL National Science Digital Library

Roughly the size of a buffalo, a giant rodent that roamed the banks of an ancient Venezuelan river some 8 million years ago, dining on sea grass and dodging crocodiles, was an evolutionary sibling to modern-day guinea pigs.

American Association for the Advancement of Science (AAAS; )

2008-07-03

43

Tropical Convection's Roles in Tropical Tropopause Cirrus  

NASA Technical Reports Server (NTRS)

The results presented here show that tropical convection plays a role in each of the three primary processes involved in the in situ formation of tropopause cirrus. First, tropical convection transports moisture from the surface into the upper troposphere. Second, tropical convection excites Rossby waves that transport zonal momentum toward the ITCZ, thereby generating rising motion near the equator. This rising motion helps transport moisture from where it is detrained from convection to the cold-point tropopause. Finally, tropical convection excites vertically propagating tropical waves (e.g. Kelvin waves) that provide one source of large-scale cooling near the cold-point tropopause, leading to tropopause cirrus formation.

Boehm, Matthew T.; Starr, David OC.; Verlinde, Johannes; Lee, Sukyoung

2002-01-01

44

Tropical Implicitization Jan Verschelde  

E-print Network

and balancing connectivity and fans stable intersection 4 Tropical Rain Forest 5 Linear Algebra Jan VerscheldeTropical Implicitization Jan Verschelde University of Illinois at Chicago Department of Mathematics Algebraic Geometry Seminar Jan Verschelde (UIC) Tropical Implicitization 6 February 2014 1 / 22 #12;Tropical

Verschelde, Jan

45

Tropical Linear Spaces  

Microsoft Academic Search

We define tropical analogues of the notions of linear space and Plucker coordinate and study their combinatorics. We introduce tropical analogues of intersection and dualization and define a tropical linear space built by repeated dualization and trans- verse intersection to be constructible. Our main result that all constructible tropical linear spaces have the same f-vector and are \\

David E. Speyer

2008-01-01

46

Can rodents conceive hyperbolic spaces?  

E-print Network

The grid cells discovered in the rodent medial entorhinal cortex have been proposed to provide a metric for Euclidean space, possibly even hardwired in the embryo. Yet one class of models describing the formation of grid unit selectivity is entirely based on developmental self-organization, and as such it predicts that the metric it expresses should reflect the environment to which the animal has adapted. We show that, according to self-organizing models, if raised in a non-Euclidean hyperbolic cage rats should be able to form hyperbolic grids. For a given range of grid spacing relative to the radius of negative curvature of the hyperbolic surface, such grids are predicted to appear as multi-peaked firing maps, in which each peak has seven neighbours instead of the Euclidean six, a prediction that can be tested in experiments. We thus demonstrate that a useful universal neuronal metric, in the sense of a multi-scale ruler and compass that remain unaltered when changing environments, can be extended to other t...

Urdapilleta, Eugenio; Stella, Federico; Treves, Alessandro

2015-01-01

47

Establishing Primary Adult Fibroblast Cultures From Rodents  

PubMed Central

The importance of using primary cells, rather than cancer cell lines, for biological studies is becoming widely recognized. Primary cells are preferred in studies of cell cycle control, apoptosis, and DNA repair, as cancer cells carry mutations in genes involved in these processes. Primary cells cannot be cultured indefinitely due to the onset of replicative senescence or aneuploidization. Hence, new cultures need to be established regularly. The procedure for isolation of rodent embryonic fibroblasts is well established, but isolating adult fibroblast cultures often presents a challenge. Adult rodent fibroblasts isolated from mouse models of human disease may be a preferred control when comparing them to fibroblasts from human patients. Furthermore, adult fibroblasts are the only available material when working with wild rodents where pregnant females cannot be easily obtained. Here we provide a protocol for isolation and culture of adult fibroblasts from rodent skin and lungs. We used this procedure successfully to isolate fibroblasts from over twenty rodent species from laboratory mice and rats to wild rodents such as beaver, porcupine, and squirrel. PMID:20972406

Seluanov, Andrei; Vaidya, Amita; Gorbunova, Vera

2010-01-01

48

Rodents as potential couriers for bioterrorism agents.  

PubMed

Many pathogens that can cause major public health, economic, and social damage are relatively easily accessible and could be used as biological weapons. Wildlife is a natural reservoir for many potential bioterrorism agents, and, as history has shown, eliminating a pathogen that has dispersed among wild fauna can be extremely challenging. Since a number of wild rodent species live close to humans, rodents constitute a vector for pathogens to circulate among wildlife, domestic animals, and humans. This article reviews the possible consequences of a deliberate spread of rodentborne pathogens. It is relatively easy to infect wild rodents with certain pathogens or to release infected rodents, and the action would be difficult to trace. Rodents can also function as reservoirs for diseases that have been spread during a bioterrorism attack and cause recurring disease outbreaks. As rats and mice are common in both urban and rural settlements, deliberately released rodentborne infections have the capacity to spread very rapidly. The majority of pathogens that are listed as potential agents of bioterrorism by the Centers for Disease Control and Prevention and the National Institute of Allergy and Infectious Diseases exploit rodents as vectors or reservoirs. In addition to zoonotic diseases, deliberately released rodentborne epizootics can have serious economic consequences for society, for example, in the area of international trade restrictions. The ability to rapidly detect introduced diseases and effectively communicate with the public in crisis situations enables a quick response and is essential for successful and cost-effective disease control. PMID:23971813

Lõhmus, Mare; Janse, Ingmar; van de Goot, Frank; van Rotterdam, Bart J

2013-09-01

49

Tropical pancreatitis.  

PubMed

Tropical pancreatitis is an uncommon cause of acute, and often chronic, relapsing pancreatitis. Patients present with abdominal pain, weight loss, pancreatic calcifications, and glucose intolerance or diabetes mellitus. Etiologies include a protein-calorie malnourished state, a variety of exogenous food toxins, pancreatic duct anomalies, and a possible genetic predisposition. Chronic cyanide exposure from the diet may contribute to this disease, seen often in India, Asia, and Africa. The pancreatic duct of these patients often is markedly dilated, and may contain stones, with or without strictures. The risk of ductal carcinoma with this disease is accentuated. Treatment may be frustrating, and may include pancreatic enzymes, duct manipulations at endoscopic retrograde cholangiopancreatography, octreotide, celiac axis blocks for pain control, or surgery via drainage and/or resection. PMID:12080228

Petersen, John M

2002-07-01

50

Rodent outbreaks in Australia: mouse plagues in cereal crops 225 Rodent outbreaks in Australia: mouse  

E-print Network

Rodent outbreaks in Australia: mouse plagues in cereal crops 225 Rodent outbreaks in Australia: mouse plagues in cereal crops Peter R. Brown, Grant R. Singleton, Roger P. Pech, Lyn A. Hinds, and Charles J. Krebs Mouse plagues have been a feature in cereal cropping areas in southeastern Australia

Krebs, Charles J.

51

The Fecal Viral Flora of Wild Rodents  

PubMed Central

The frequent interactions of rodents with humans make them a common source of zoonotic infections. To obtain an initial unbiased measure of the viral diversity in the enteric tract of wild rodents we sequenced partially purified, randomly amplified viral RNA and DNA in the feces of 105 wild rodents (mouse, vole, and rat) collected in California and Virginia. We identified in decreasing frequency sequences related to the mammalian viruses families Circoviridae, Picobirnaviridae, Picornaviridae, Astroviridae, Parvoviridae, Papillomaviridae, Adenoviridae, and Coronaviridae. Seventeen small circular DNA genomes containing one or two replicase genes distantly related to the Circoviridae representing several potentially new viral families were characterized. In the Picornaviridae family two new candidate genera as well as a close genetic relative of the human pathogen Aichi virus were characterized. Fragments of the first mouse sapelovirus and picobirnaviruses were identified and the first murine astrovirus genome was characterized. A mouse papillomavirus genome and fragments of a novel adenovirus and adenovirus-associated virus were also sequenced. The next largest fraction of the rodent fecal virome was related to insect viruses of the Densoviridae, Iridoviridae, Polydnaviridae, Dicistroviriade, Bromoviridae, and Virgaviridae families followed by plant virus-related sequences in the Nanoviridae, Geminiviridae, Phycodnaviridae, Secoviridae, Partitiviridae, Tymoviridae, Alphaflexiviridae, and Tombusviridae families reflecting the largely insect and plant rodent diet. Phylogenetic analyses of full and partial viral genomes therefore revealed many previously unreported viral species, genera, and families. The close genetic similarities noted between some rodent and human viruses might reflect past zoonoses. This study increases our understanding of the viral diversity in wild rodents and highlights the large number of still uncharacterized viruses in mammals. PMID:21909269

Phan, Tung G.; Kapusinszky, Beatrix; Wang, Chunlin; Rose, Robert K.; Lipton, Howard L.; Delwart, Eric L.

2011-01-01

52

The tropical Grassmannian  

Microsoft Academic Search

In tropical algebraic geometry, the solution sets of polynomial equations are\\u000apiecewise-linear. We introduce the tropical variety of a polynomial ideal, and\\u000awe identify it with a polyhedral subcomplex of the Grobner fan. The tropical\\u000aGrassmannian arises in this manner from the ideal of quadratic Plucker\\u000arelations. It is shown to parametrize all tropical linear spaces. Lines in\\u000atropical projective

David Speyer; Bernd Sturmfels

2004-01-01

53

Indigenous tropical ecology.  

PubMed

Two major works on the ecology of Sumatra and Sulawesi two of the world's great tropical islands, have appeared relatively recently. These volumes represent the rarest of genres in tropical ecology: works of indigenous origin with an indigenous audience in mind. An examination of these exciting books prompts us to examine a wider literature on tropical ecology. PMID:21227324

Kitching, R; Clarke, C

1989-03-01

54

Northwestern University New Researcher Checklist: Evanston Campus Rodent Users  

E-print Network

and Access to CCM Facilities Register for Facility Orientation and Hands-On Rodent Euthanasia o Contact the CCM Training Office to register for Facility Orientation and Hands-On Rodent Euthanasia training: 312-503-2758 o Facility Orientation and Hands-On Rodent Euthanasia are: Held on Tuesdays at 10:30am and Fridays

Contractor, Anis

55

Tongue Cooling: A New Reward for Thirsty Rodents  

Microsoft Academic Search

Thirsty rodents will persistently lick a stream of dry air pumped through a standard drinking tube. This air-licking is attenuated by experimental manipulations which reduce the evaporative cooling of the tongue and mouth produced by the airstream. This suggests that such cooling is itself an effective reward for thirsty rodents. We tested this hypothesis by presenting thirsty rodents with a

Joseph Mendelson; Dana Chillag

1970-01-01

56

Social Learning of Food Preferences in Rodents: Rapid Appetitive Learning  

E-print Network

, and there is an extensive literature describing both causes and consequences of social effects on food preference in rodentsSocial Learning of Food Preferences in Rodents: Rapid Appetitive Learning For the neuroscientist studying the consequences of manipulation of specific regions of the brain on learning in rodents

Galef Jr., Bennett G.

57

NEOSPORA CANINUM DETECTED IN WILD RODENTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The role of rodents in the epidemiology of neosporosis was investigated by assaying brain tissue of wild mice and rats for Neospora caninum. Both mouse and rat brain tissue were extracted for total DNA, and subjected to two different N. caninum-specific nested PCR assays. A portion of brain tissue...

58

Object Recognition Memory and the Rodent Hippocampus  

ERIC Educational Resources Information Center

In rodents, the novel object recognition task (NOR) has become a benchmark task for assessing recognition memory. Yet, despite its widespread use, a consensus has not developed about which brain structures are important for task performance. We assessed both the anterograde and retrograde effects of hippocampal lesions on performance in the NOR…

Broadbent, Nicola J.; Gaskin, Stephane; Squire, Larry R.; Clark, Robert E.

2010-01-01

59

Too many rodent carcinogens: Mitogenesis increases mutagenesis  

Microsoft Academic Search

A clarification of the mechanism of carcinogenesis is developing at a rapid rate. This new understanding undermines many assumptions of current regulatory policy toward rodent carcinogens and necessitates rethinking the utility and meaning of routine animal cancer tests. At a recent watershed meeting on carcinogenesis, much evidence was presented suggesting that mitogenesis plays a dominant role in carcinogenesis. Our own

B. N. Ames; L. S. Gold

1990-01-01

60

Novel Rodent Models for Macular Research  

PubMed Central

Background Many disabling human retinal disorders involve the central retina, particularly the macula. However, the commonly used rodent models in research, mouse and rat, do not possess a macula. The purpose of this study was to identify small laboratory rodents with a significant central region as potential new models for macular research. Methodology/Principal Findings Gerbillus perpallidus, Meriones unguiculatus and Phodopus campbelli, laboratory rodents less commonly used in retinal research, were subjected to confocal scanning laser ophthalmoscopy (cSLO), fluorescein and indocyanine green angiography, and spectral-domain optical coherence tomography (SD-OCT) using standard equipment (Heidelberg Engineering HRA1 and Spectralis™) adapted to small rodent eyes. The existence of a visual streak-like pattern was assessed on the basis of vascular topography, retinal thickness, and the topography of retinal ganglion cells and cone photoreceptors. All three species examined showed evidence of a significant horizontal streak-like specialization. cSLO angiography and retinal wholemounts revealed that superficial retinal blood vessels typically ramify and narrow into a sparse capillary net at the border of the respective area located dorsal to the optic nerve. Similar to the macular region, there was an absence of larger blood vessels in the streak region. Furthermore, the thickness of the photoreceptor layer and the population density of neurons in the ganglion cell layer were markedly increased in the visual streak region. Conclusions/Significance The retinal specializations of Gerbillus perpallidus, Meriones unguiculatus and Phodopus campbelli resemble features of the primate macula. Hence, the rodents reported here may serve to study aspects of macular development and diseases like age-related macular degeneration and diabetic macular edema, and the preclinical assessment of therapeutic strategies. PMID:20976212

Huber, Gesine; Heynen, Severin; Imsand, Coni; vom Hagen, Franziska; Muehlfriedel, Regine; Tanimoto, Naoyuki; Feng, Yuxi; Hammes, Hans-Peter; Grimm, Christian; Peichl, Leo; Seeliger, Mathias W.; Beck, Susanne C.

2010-01-01

61

Meal-feeding rodents and toxicology research.  

PubMed

Most laboratory rodents used for toxicology studies are fed ad libitum, with unlimited access to food. As a result, ad libitum-fed rodents tend to overeat. Research demonstrates that ad libitum-fed rodents are physiologically and metabolically different from rodents fed controlled amounts of food at scheduled times (meal-fed). Ad libitum-fed rodents can develop hypertriglyceridemia, hypercholesterolemia, diet-induced obesity, nephropathy, cardiomyopathy, and pituitary, pancreatic, adrenal, and thyroid tumors, conditions likely to affect the results of toxicology research studies. In contrast, meal-feeding synchronizes biological rhythms and leads to a longer life span, lower body weight, lower body temperature, hypertrophy of the small intestine, and synchronization of hepatic and digestive enzymes. The circadian rhythms present in nearly all living organisms are entrained by light intensity and food intake, and peripheral clocks in all organs of the body, especially the GI tract and liver, are particularly sensitive to food intake. Feeding schedule has been demonstrated to alter the toxicity and metabolism of drugs including sodium valproate, chloral hydrate, acetaminophen, gentamicin, and methotrexate. Feeding schedule alters the expression of genes that code for Phase I, II, and III proteins, thereby altering the rate and amplitude of drug disposition. Rhythms of plasma insulin and glucagon that fluctuate with food ingestion are also altered by feeding schedule; ad libitum feeding promotes hyperinsulinemia which is a precursor for developing diabetes. The emerging field of chronopharmacology, the interaction of biological rhythms and drugs, will lead to optimizing the design and delivery of drugs in a manner that matches biological rhythms, but it is wise for toxicology researchers to consider feeding schedule when designing these experiments. It has been 10 years since the Society for Toxicologic Pathology voiced its position that feeding schedule is an important variable that should be controlled in toxicology experiments, and research continues to underscore this position. PMID:22642213

Carey, Gale B; Merrill, Lisa C

2012-08-20

62

Rodents as reservoirs of parasites in India.  

PubMed

We monitored the prevalence of endoparasitic infections of rodents in Punjab State, India, between January 2004 and December 2005. Three species of wild rodents, namely the house rat, Rattus rattus (n= 42), the lesser bandicoot rat, Bandicota bengalensis (n= 34) and the Indian gerbil, Tatera indica (n= 15), were live-captured from houses and crop fields. Examination of various organs revealed that the highest rates of endoparasitic infection occurred in R. rattus (40.5%), followed by B. bengalensis (35.3 %) and then T. indica (20.0%), with an overall infection rate of 35.2%. All three rodent species were found naturally infected with one or more species of helminths. Metacestodes (1-6) of Cysticercus fasciolaris (larvae of Taenia taeniaeformis) were found in all three rodent species (in the liver). In one male T. indica, numerous robust T. taeniaeformis metacestodes were found in oval sacs attached to the mesentery and the abdominal wall, an unusual site. The cauda epididymal fluid of the same gerbil was also found to be infected with a very rare species of strongylid nematode, which could not be identified to genus or species level. It is possible that this nematode is transmitted sexually and thus may affect the reproductive potential of gerbils. This appears to be the first report of this phenomenon. In one B. bengalensis individual, the intestine was found to be obstructed with an acanthocephalan, Moniliformis moniliformis, with concurrent infection with C. fasciolaris in the form of multiple cysts in the liver. Although no natural protozoan infection was found in these field rodents, experimental Trypanosoma evansi infection has been established in all three species with high pathogenicity, and the possibility of sexual transmission was supported by the presence of T. evansi in the cauda epididymal fluid of male rats. PMID:21396047

Singla, Lachhman D; Singla, Neena; Parshad, Vir R; Juyal, Prayag D; Sood, Naresh K

2008-03-01

63

Molecular epidemiology of paramyxoviruses in Zambian wild rodents and shrews.  

PubMed

Rodents and shrews are known to harbour various viruses. Paramyxoviruses have been isolated from Asian and Australian rodents, but little is known about them in African rodents. Recently, previously unknown paramyxovirus sequences were found in South African rodents. To date, there have been no reports related to the presence and prevalence of paramyxoviruses in shrews. We found a high prevalence of paramyxoviruses in wild rodents and shrews from Zambia. Semi-nested reverse transcription-PCR assays were used to detect paramyxovirus RNA in 21 % (96/462) of specimens analysed. Phylogenetic analysis revealed that these viruses were novel paramyxoviruses and could be classified as morbillivirus- and henipavirus-related viruses, and previously identified rodent paramyxovirus-related viruses. Our findings suggest the circulation of previously unknown paramyxoviruses in African rodents and shrews, and provide new information regarding the geographical distribution and genetic diversity of paramyxoviruses. PMID:24189618

Sasaki, Michihito; Muleya, Walter; Ishii, Akihiro; Orba, Yasuko; Hang'ombe, Bernard M; Mweene, Aaron S; Moonga, Ladslav; Thomas, Yuka; Kimura, Takashi; Sawa, Hirofumi

2014-02-01

64

Tropical Convection's Roles in Tropical Tropopause Cirrus  

NASA Technical Reports Server (NTRS)

Remote sensing observations reveal the frequent occurrence of tropopause cirrus, thin cirrus layers located near the tropical cold-point tropopause. Here, we present a theory in which tropical convection plays several important roles in tropopause cirrus formation. First, tropical convection is the primary means by which the moisture required for tropopause cirrus formation is transported into the upper troposphere. However, previous studies suggest that this convection rarely penetrates to the altitudes at which tropopause cirrus layers are observed, suggesting that additional vertical moisture transport is required to explain tropopause cirrus formation. We propose a mechanism for explaining this transport in which tropical convection plays the key role. According to this hypothesis, the transport is accomplished by meridional circulations that develop within the tropopause transition layer (TTL) in response to momentum transport by Rossby waves generated by tropical convection. Results of a series of global scale model runs designed to test this hypothesis will be presented. In addition, reanalyses vertical velocity data will be examined for evidence of the expected correlation between large-scale rising motion within the TTL and tropical convection. Once moisture is present near the cold-point tropopause, large-scale cooling is required to initiate tropopause cirrus formation. One source of this cooling is stratospheric tropical waves induced by tropical convection, as we will show using a time series of radiosonde temperature data superimposed with data on cloud occurrence from the DOE ARM Nauru99 field experiment. Observations of the global characteristics of these waves from a longer time series of reanalysis data will also be presented.

Boehm, Matthew T.; Starr, David OC.; Verlinde, Johannes; Lee, Sukyoung

2002-01-01

65

REVIEW: GENETIC MANIPULATION OF THE RODENT PLACENTA  

PubMed Central

The principal role of the placenta is the maintenance of pregnancy and promotion of fetal growth and viability. The use of transgenic rodents has greatly enhanced our understanding of placental development and function. However, embryonic lethality is often a confounding variable in determining whether a genetic modification adversely affected placental development. In these cases, it is beneficial to specifically manipulate the placental genome. The purpose of this review is to summarize available methodologies for specific genetic modification of the rodent placenta. By restricting genetic alterations to the trophoblast lineage, it is possible to gain a deeper understanding of placental development that perhaps will lead to gene-targeted therapies to rescue irregular placentation in transgenic animals or in women at high-risk for placenta-associated pregnancy complications. PMID:21256588

Renaud, Stephen J.; Rumi, M.A. Karim; Soares, Michael J.

2011-01-01

66

Rodent models of TDP-43: Recent advances  

PubMed Central

Recently, missense mutations in the gene TARDBP encoding TDP-43 have been linked to familial ALS. The discovery of genes encoding these RNA binding proteins, such as TDP-43 and FUS/TLS, raised the notion that altered RNA metabolism is a major factor underlying the pathogenesis of ALS. To begin to unravel how mutations in TDP-43 cause dysfunction and death of motor neurons, investigators have employed both gain- and loss-of-function studies in rodent model systems. Here, we will summarize major findings from the initial sets of TDP-43 transgenic and knockout rodent models, identify their limitations, and point to future directions toward clarification of disease mechanism(s) and testing of therapeutic strategies that ultimately may lead to novel therapy for this devastating disease. PMID:22608070

Tsao, William; Jeong, Yun Ha; Lin, Sophie; Ling, Jonathan; Price, Donald L.; Chiang, Po-Min; Wong, Philip C.

2013-01-01

67

Enzootic Rabies in Rodents in Thailand  

Microsoft Academic Search

RABIES virus has occasionally been isolated from feral rats1 and yet rodents are not considered to be a significant reservoir of sylvatic rabies2. These conclusions are based on negative results of surveys of small mammal species in areas in which rabies is endemic2,3. The isolation of rabies virus from a field rat, Bandicoota indicus, in the course of routine diagnostic

Paul C. Smith; Kwanyuen Lawhaswasdi; William E. Vick; Jack S. Stanton

1968-01-01

68

Evidence for Novel Hepaciviruses in Rodents  

PubMed Central

Hepatitis C virus (HCV) is among the most relevant causes of liver cirrhosis and hepatocellular carcinoma. Research is complicated by a lack of accessible small animal models. The systematic investigation of viruses of small mammals could guide efforts to establish such models, while providing insight into viral evolutionary biology. We have assembled the so-far largest collection of small-mammal samples from around the world, qualified to be screened for bloodborne viruses, including sera and organs from 4,770 rodents (41 species); and sera from 2,939 bats (51 species). Three highly divergent rodent hepacivirus clades were detected in 27 (1.8%) of 1,465 European bank voles (Myodes glareolus) and 10 (1.9%) of 518 South African four-striped mice (Rhabdomys pumilio). Bats showed anti-HCV immunoblot reactivities but no virus detection, although the genetic relatedness suggested by the serologic results should have enabled RNA detection using the broadly reactive PCR assays developed for this study. 210 horses and 858 cats and dogs were tested, yielding further horse-associated hepaciviruses but none in dogs or cats. The rodent viruses were equidistant to HCV, exceeding by far the diversity of HCV and the canine/equine hepaciviruses taken together. Five full genomes were sequenced, representing all viral lineages. Salient genome features and distance criteria supported classification of all viruses as hepaciviruses. Quantitative RT-PCR, RNA in-situ hybridisation, and histopathology suggested hepatic tropism with liver inflammation resembling hepatitis C. Recombinant serology for two distinct hepacivirus lineages in 97 bank voles identified seroprevalence rates of 8.3 and 12.4%, respectively. Antibodies in bank vole sera neither cross-reacted with HCV, nor the heterologous bank vole hepacivirus. Co-occurrence of RNA and antibodies was found in 3 of 57 PCR-positive bank vole sera (5.3%). Our data enable new hypotheses regarding HCV evolution and encourage efforts to develop rodent surrogate models for HCV. PMID:23818848

Drexler, Jan Felix; Corman, Victor Max; Müller, Marcel Alexander; Lukashev, Alexander N.; Gmyl, Anatoly; Coutard, Bruno; Adam, Alexander; Ritz, Daniel; Leijten, Lonneke M.; van Riel, Debby; Kallies, Rene; Klose, Stefan M.; Gloza-Rausch, Florian; Binger, Tabea; Annan, Augustina; Adu-Sarkodie, Yaw; Oppong, Samuel; Bourgarel, Mathieu; Rupp, Daniel; Hoffmann, Bernd; Schlegel, Mathias; Kümmerer, Beate M.; Krüger, Detlev H.; Schmidt-Chanasit, Jonas; Setién, Alvaro Aguilar; Cottontail, Veronika M.; Hemachudha, Thiravat; Wacharapluesadee, Supaporn; Osterrieder, Klaus; Bartenschlager, Ralf; Matthee, Sonja; Beer, Martin; Kuiken, Thijs; Reusken, Chantal; Leroy, Eric M.; Ulrich, Rainer G.; Drosten, Christian

2013-01-01

69

Geometric Morphometrics of Rodent Sperm Head Shape  

PubMed Central

Mammalian spermatozoa, particularly those of rodent species, are extremely complex cells and differ greatly in form and dimensions. Thus, characterization of sperm size and, particularly, sperm shape represents a major challenge. No consensus exists on a method to objectively assess size and shape of spermatozoa. In this study we apply the principles of geometric morphometrics to analyze rodent sperm head morphology and compare them with two traditional morphometry methods, that is, measurements of linear dimensions and dimensions-derived parameters calculated using formulae employed in sperm morphometry assessments. Our results show that geometric morphometrics clearly identifies shape differences among rodent spermatozoa. It is also capable of discriminating between size and shape and to analyze these two variables separately. Thus, it provides an accurate method to assess sperm head shape. Furthermore, it can identify which sperm morphology traits differ between species, such as the protrusion or retraction of the base of the head, the orientation and relative position of the site of flagellum insertion, the degree of curvature of the hook, and other distinct anatomical features and appendices. We envisage that the use of geometric morphometrics may have a major impact on future studies focused on the characterization of sperm head formation, diversity of sperm head shape among species (and underlying evolutionary forces), the effects of reprotoxicants on changes in cell shape, and phenotyping of genetically-modified individuals. PMID:24312234

Varea Sánchez, María; Bastir, Markus; Roldan, Eduardo R. S.

2013-01-01

70

Spontaneous Type 2 Diabetic Rodent Models  

PubMed Central

Diabetes mellitus, especially type 2 diabetes (T2DM), is one of the most common chronic diseases and continues to increase in numbers with large proportion of health care budget being used. Many animal models have been established in order to investigate the mechanisms and pathophysiologic progress of T2DM and find effective treatments for its complications. On the basis of their strains, features, advantages, and disadvantages, various types of animal models of T2DM can be divided into spontaneously diabetic models, artificially induced diabetic models, and transgenic/knockout diabetic models. Among these models, the spontaneous rodent models are used more frequently because many of them can closely describe the characteristic features of T2DM, especially obesity and insulin resistance. In this paper, we aim to investigate the current available spontaneous rodent models for T2DM with regard to their characteristic features, advantages, and disadvantages, and especially to describe appropriate selection and usefulness of different spontaneous rodent models in testing of various new antidiabetic drugs for the treatment of type 2 diabetes. PMID:23671868

Wang, Yang-wei; Sun, Guang-dong; Sun, Jing; Liu, Shu-jun; Wang, Ji; Xu, Xiao-hong; Miao, Li-ning

2013-01-01

71

Liver tumors in rodents: extrapolation to man.  

PubMed

Man is a poor model for the prediction of agents that are hepatocarcinogenic for laboratory rodents. Relatively few agents are known to cause any form of primary liver cancer in man. The most important is hepatitis B virus, for which there is possibly a model in the woodchuck but not one in rats or mice. The only other agents known to cause primary liver cancer in man are certain steroid hormones, vinyl chloride, and thorium dioxide. There are animal models for the first two of these and a reasonable expectation that thorium dioxide would produce liver tumors in animals if the appropriate experiments were done. Aflatoxin, a potent hepatocarcinogen in rats and other species but not mice, is strongly suspected of being an important human hepatocarcinogen in certain geographical areas of the world, but the evidence is circumstantial. There is no more than a weak association between the nutritional type of cirrhosis secondary to excessive intake of alcohol and increased primary liver cancer in man, and no evidence at all that ethanol per se causes liver tumors in mice, rats, hamsters, or mastomys. By contrast, a very large number of chemicals to which people in the West have been exposed for many decades have been found to be hepatocarcinogens in laboratory rodents. In most cases the levels of exposure required to produce liver tumors in rodents far exceed those to which man is normally exposed. The problem is to guess whether low-level exposure to such rodent hepatocarcinogens poses any real liver cancer threat to man?The mortality from primary liver cancer is very low in countries such as England and Wales where there is widespread exposure to low doses of both natural and synthetic agents which, in high dosage, cause liver tumors in rodents. This suggests that, if there is any risk, it can only be very small. Death rate data collected in England and Wales by the Registrar General are consistent with there having been a small increase in the incidence of primary liver cancer in England and Wales during the past 20 years, but the apparent increase might well be a consequence of revisions in the International Classification of Diseases system and not real. During the first half of the present century the age-standardized incidence of primary liver cancer in England and Wales was falling.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3300204

Roe, F J

1987-01-01

72

[Tropical or non-tropical sprue?].  

PubMed

A 57-year-old Dutch man presented with weight loss and fatigue 6 months after a visit to West Papua, when he had suffered from serious diarrhoea. Macrocytic anaemia and vitamin B12 deficiency were diagnosed. A gastroduodenoscopy with biopsies of the small intestine was performed revealing no macroscopic abnormalities but partial villous atrophy was found microscopically, suggesting tropical sprue or coeliac disease. Antibodies against endomysium and tissue transglutaminase were negative, ruling out coeliac disease. The patient was successfully treated with vitamin B12, folic acid and doxycycline. This case shows that tropical sprue should be considered in the differential diagnosis of chronic diarrhoea in patients with a history of travel in tropical regions. The most frequent medical problem that travelers to the tropics experience is diarrhoea with an incidence of 30%. A small proportion of these patients eventually present with chronic diarrhoea. At that moment, the relation to their previous travelling may not be immediately clear. One of the causes of this chronic diarrhoea to be considered is tropical sprue. PMID:16261708

Sankatsing, S U C; Leguit, R J; ten Kate, F J W; Wetsteyn, J C F M

2005-10-15

73

The guinea-pig is not a rodent  

Microsoft Academic Search

IN 1991 Graur et al. raised the question of whether the guinea-pig, Cavia porcellus, is a rodent1. They suggested that the guinea-pig and myomorph rodents diverged before the separation between myomorph rodents and a lineage leading to primates and artiodactyls. Several findings have since been reported, both for and against this phylogeny, thereby highlighting the issue of the validity of

Anna Maria D'Erchia; Carmela Gissi; Graziano Pesole; Cecilia Saccone; Ulfur Arnason

1996-01-01

74

Computing tropical varieties  

Microsoft Academic Search

The tropical variety of a d-dimensional prime ideal in a polynomial ring with complex coefficients is a pured-dimensional poly- hedral fan. This fan is shown to be connected in codimension one. We present algorithmic tools for computing the tropical variety, and we dis- cuss our implementation of these tools in the Grobner fan software Gfan. Every ideal is shown to

Tristram Bogart; Anders Jensen; David Speyer; Bernd Sturmfels; Rekha R. Thomas

2007-01-01

75

Tropical Prediction Center  

NSDL National Science Digital Library

The Tropical Prediction Center Web site is maintained by the National Weather Service of NOAA. Visitors will find current information on tropical storms and hurricanes, including public advisories. Also available are hurricane facts, historical data, tracking charts, satellite imagery, season summaries, and a wealth of other interesting and important information.

76

TROPICAL SPIDERWORT - AN INTRODUCTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tropical spiderwort (also known as Benghal dayflower) has gone from relative obscurity as a roadside curiosity to troublesome weed with widespread economic impact in Georgia in less than 10 years. South Georgia and Florida are currently plagued by tropical spiderwort, but isolated populations have ...

77

Topics in Tropical Meteorology  

NSDL National Science Digital Library

This module brings together six short lessons about significant atmospheric and oceanic influences on tropical cyclone development in the Atlantic Ocean. Topics treated include the African Easterly Jet, the Loop Current, the Meridional Overturning Circulation, ocean heat content, the Saharan Air Layer, and the Tropical Upper Tropospheric Trough, or TUTT.

COMET

2008-12-22

78

Susceptibility of laboratory rodents to Trichinella papuae.  

PubMed

Members of the genus Trichinella are small nematodes that can infect a wide range of animal hosts. However, their infectivity varies depending on the parasite and host species combination. In this study, we examined the susceptibility of 4 species of laboratory rodents, i.e., mice, rats, hamsters, and gerbils to Trichinella papuae, an emerging non-encapsulated Trichinella species. Trichinella spiralis and Trichinella pseudospiralis were also included in this study for comparison. Fifteen animals of each rodent species were infected orally with 100 muscle larvae of each Trichinella species. Intestinal worm burden was determined at day 6 and 10 post-inoculation (PI). The numbers of muscle larvae were examined at day 45 PI. The reproductive capacity index (RCI) of the 3 Trichinella species in different rodent hosts was determined. By day 6 PI, 33.2-69.6% of the inoculated larvae of the 3 Trichinella species became adult worms in the small intestines of the host animals. However, in rats, more than 96% of adult worms of all 3 Trichinella species were expelled from the gut by day 10 PI. In gerbils, only 4.8-18.1% of adult worms were expelled by day 10 PI. In accordance with the intestinal worm burden and the persistence of adults, the RCI was the highest in gerbils with values of 241.5±41.0 for T. papuae, 432.6±48 for T. pseudospiralis, and 528.6±20.6 for T. spiralis. Hamsters ranked second and mice ranked third in susceptibility in terms of the RCI, Rats yielded the lowest parasite RCI for all 3 Trichinella species. Gerbils may be an alternative laboratory animal for isolation and maintenance of Trichinella spp. PMID:24516265

Sadaow, Lakkhana; Intapan, Pewpan M; Boonmars, Thidarut; Morakote, Nimit; Maleewong, Wanchai

2013-12-01

79

Conceptual Models of Tropical Waves  

NSDL National Science Digital Library

Tropical waves are prolific rainfall producers that sometimes form tropical cyclones. Conceptual models of tropical waves are used to help learners understand the dynamical characteristics and evolution of tropical waves. Users will learn about the vertical and horizontal structure of tropical waves and the typical weather changes that accompany the passage of a tropical wave. Four different methods of tracking tropical waves are also provided. The Webcast is presented by Mr. Horace Burton and Mr. Selvin Burton of the Caribbean Institute for Meteorology and Hydrology under the auspices of the MeteoForum Project.

COMET

2006-04-21

80

Small wild rodents rabies in Czechoslovakia.  

PubMed

During a period of 1969-1979 a total of 3174 small wild rodents of the genus Muridae and Microtinae (predominantly Microtus arvalis) were examined. The animals were trapped in five localities differing both in type of ecological conditions and epizootologic situation. Fox-rabies occurred here either enzootically, or epizootologically, or had been completely absent for many years in one of the localities investigated. Of the 71 isolated strains of RV 18 strains were isolated from brain, 25 from brown fat and 28 from salivary glands. Simultaneous isolation positivity in more than one tissue was sporadic. Virus isolations from deep-frozen material were mostly unsuccessful. Basic biological characteristics were determined in each isolate. The isolated strains differed in the rate of adaptation on albino mice and in intracerebral virulence. All isolates exhibited extraneural pathogenicity for common laboratory animals, dogs and foxes, showed distinct viscerotropism, stimulated formation of interferon and produced various forms of non-lethal infection. Incidence of "murine" rabies did not show any locality-specific differences and in longitudinally studied areas was enzootic. In a number of Czech districts there was observed a distinct relationship between fox-rabies incidence and the density of small game animal populations. Role of small wild rodents in the epizootology and epidemiology of rabies is discussed. PMID:6749977

Sodja, I; Lím, D; Matouch, O; Seidlová, A; Farník, J; Svec, J; Cerný, J; Klimes, A

1982-01-01

81

Rodent models of treatment-resistant depression.  

PubMed

Major depression is a prevalent and debilitating disorder and a substantial proportion of patients fail to reach remission following standard antidepressant pharmacological treatment. Limited efficacy with currently available antidepressant drugs highlights the need to develop more effective medications for treatment- resistant patients and emphasizes the importance of developing better preclinical models that focus on treatment- resistant populations. This review discusses methods to adapt and refine rodent behavioral models that are predictive of antidepressant efficacy to identify populations that show reduced responsiveness or are resistant to traditional antidepressants. Methods include separating antidepressant responders from non-responders, administering treatments that render animals resistant to traditional pharmacological treatments, and identifying genetic models that show antidepressant resistance. This review also examines pharmacological and non-pharmacological treatments regimes that have been effective in refractory patients and how some of these approaches have been used to validate animal models of treatment-resistant depression. The goals in developing rodent models of treatment-resistant depression are to understand the neurobiological mechanisms involved in antidepressant resistance and to develop valid models to test novel therapies that would be effective in patients that do not respond to traditional monoaminergic antidepressants. PMID:25460020

Caldarone, Barbara J; Zachariou, Venetia; King, Sarah L

2015-04-15

82

Tropical Storms, Worldwide  

NSDL National Science Digital Library

The University of Hawaii's Mees Solar Observatory, stationed at Haleakala, Maui, provides a wealth of data and images in its Webpages. This page, Tropical Storms Worldwide, gives regional maps and written updates of hurricane, typhoon, and tropical cyclone activity around the globe. The page also features a strike probability calculator where users click on a list of geographic locations or enter map coordinates or a US zip code in order to view the probability of a tropical storm reaching that area. A storm data archive (1994-2000) and printer-friendly .pdf-formatted storm track maps are also available.

83

Competition between harvester ants and rodents in the cold desert  

Microsoft Academic Search

Local distribution patterns of three rodent species (Perognathus parvus, Peromyscus maniculatus, Reithrodontomys megalotis) were studied in areas of high and low densities of harvester ants (Pogonomyrmex owyheei) in Raft River Valley, Idaho. Numbers of rodents were greatest in areas of high ant-density during May, but partially reduced in August; whereas, the trend was reversed in areas of low ant-density. Seed

D. S. Landeen; C. D. Jorgensen; H. D. Smith

1979-01-01

84

Genome sequence and comparative analysis of the model rodent malaria  

E-print Network

Genome sequence and comparative analysis of the model rodent malaria parasite Plasmodium yoelii Medical Centre, PO Box 9600, 2300 RC Leiden, The Netherlands § Naval Medical Research Center, Malaria ........................................................................................................................................................................................................................... Species of malaria parasite that infect rodents have long been used as models for malaria disease research

Salzberg, Steven

85

Visual Landmarks Facilitate Rodent Spatial Navigation in Virtual Reality Environments  

ERIC Educational Resources Information Center

Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain…

Youngstrom, Isaac A.; Strowbridge, Ben W.

2012-01-01

86

Vitamin K Contents of Rodent Diets: A Review  

Technology Transfer Automated Retrieval System (TEKTRAN)

Adequate nutrient intake is critical in the maintenance of normal physiological activity of rodents in biomedical studies. Vitamin K is an essential nutrient in rodent diets and functions as a cofactor for the y-carboxylation of certain proteins involved in blood coagulation and bone metabolism. Dif...

87

Breath-hold Device for Laboratory Rodents Undergoing Imaging Procedures  

Microsoft Academic Search

The increased use in noninvasive imaging of laboratory rodents has prompted innovative techniques in animal han- dling. Lung imaging of rodents can be a diffi cult task because of tissue motion caused by breathing, which affects image quality. The use of a prototype fl at-panel computed tomography unit allows the acquisition of images in as little as 2, 4, or

Belinda Rivera; Mark J Bushman; Richard G Beaver; Dianna D Cody; Roger E Price

88

PREDICTIVE SIMULATION MODELING FOR ANTIANDROGEN IMPACTS ON RODENT PROSTATE  

EPA Science Inventory

Predictive simulation modeling for antiandrogen impacts on rodent prostate HA Barton1, RW Setzer1, LK Potter1,2 1US EPA, ORD, NHEERL, ETD, PKB, Research Triangle Park, NC and 2Curriculum in Toxicology, UNC, Chapel Hill, NC Changes in rodent prostate weight and functi...

89

Natural selection and the genetic basis of osmoregulation in heteromyid rodents as revealed by RNA-seq.  

PubMed

One adaptation of ecological and evolutionary interest is the extraordinary ability of desert rodents to retain water during waste production. Much is known regarding the unique kidney physiology of kangaroo rats (Dipodomys spp.) and their ability to retain water during waste production, yet the genetic basis of these physiological adaptations is relatively unknown. Herein, we utilized RNA-seq data to conduct a comparative study to identify osmoregulatory genes expressed in heteromyid rodents. We sequenced kidney tissue from two temperate desert species (Dipodomys spectabilis and Chaetodipus baileyi) from two separate subfamilies of the Heteromyidae and compared these transcriptomes to a tropical mesic species (Heteromys desmarestianus) from a third subfamily. The evolutionary history of these subfamilies provided a robust phylogenetic control that allowed us to separate shared evolutionary history from convergence. Using two methods to detect differential expression (DE), we identified 1890 genes that showed consistent patterns of DE between the arid and mesic species. A three-species reciprocal BLAST analysis revealed 3511 sets of putative orthologues that, upon comparison to known Mus musculus sequences, revealed 323 annotated and full-length genic regions. Selection tests displayed evidence of positive selection (dn/ds > 1) on six genes in the two desert species and remained significant for one of these genes after correction for multiple testing. Thus, our data suggest that both the coding sequence and expression of genes have been shaped by natural selection to provide the genetic architecture for efficient osmoregulation in desert-adapted heteromyid rodents. PMID:24754676

Marra, Nicholas J; Romero, Andrea; DeWoody, J Andrew

2014-06-01

90

Deforestation in the Tropics  

SciTech Connect

Government policies that encourage exploitation--in particular excessive logging and clearing for ranches and farms--are largely to blame for the accelerating destruction of tropical forests. This paper surveys the problem in detail and briefly recommends potential solutions.

Repetto, R. (World Resources Institute, Washington, DC (USA))

1990-04-01

91

Scatter-Hoarding Rodents Prefer Slightly Astringent Food  

PubMed Central

The mutualistic interaction between scatter-hoarding rodents and their seed plants is highly complex yet poorly understood. Plants may benefit from the seed dispersal behavior of rodents, as long as seed consumption is minimized. In parallel, rodents may maximize foraging efficiency and cache high-quality resources for future consumption. Defensive compounds, such as tannins, are thought to be a major mechanism for plant control over rodent behavior. However, previous studies, using naturally occurring seeds, have not provided conclusive evidence supporting this hypothesis. Here, we test the importance of tannin concentrations on the scatter-hoarding behavior of rodents by using an artificial seed system. We combined feeding trials and field observations to examine the overall impact of seed tannin concentrations on rodent behavior and health. We found that rodents favored seeds with an intermediate amount of tannin (?5%) in the field. Meanwhile, in rodents that were fed a diet with different tannin content, only diets with high tannin content (25%, 15%, and 10%) caused a significant negative influence on rodent survival and health. Significant differences were not found among treatments with tannin levels of 0–5%. In contrast to many existing studies, our results clearly demonstrate that scatter-hoarding rodents prefer slightly ‘astringent’ food. In the co-evolutionary arms race between plants and animals, our results suggest that while tannins may play a significant role in reducing general predation levels by the faunal community, they have no precise control over the behavior of their mutualistic partner. Instead, the two partners appear to have reached an evolutionary point where both parties receive adequate benefits, with the year-to-year outcome being dependent on a wide range of factors beyond the control of either partner. PMID:22046284

Wang, Bo; Chen, Jin

2011-01-01

92

Scatter-hoarding rodents prefer slightly astringent food.  

PubMed

The mutualistic interaction between scatter-hoarding rodents and their seed plants is highly complex yet poorly understood. Plants may benefit from the seed dispersal behavior of rodents, as long as seed consumption is minimized. In parallel, rodents may maximize foraging efficiency and cache high-quality resources for future consumption. Defensive compounds, such as tannins, are thought to be a major mechanism for plant control over rodent behavior. However, previous studies, using naturally occurring seeds, have not provided conclusive evidence supporting this hypothesis. Here, we test the importance of tannin concentrations on the scatter-hoarding behavior of rodents by using an artificial seed system. We combined feeding trials and field observations to examine the overall impact of seed tannin concentrations on rodent behavior and health. We found that rodents favored seeds with an intermediate amount of tannin (~5%) in the field. Meanwhile, in rodents that were fed a diet with different tannin content, only diets with high tannin content (25%, 15%, and 10%) caused a significant negative influence on rodent survival and health. Significant differences were not found among treatments with tannin levels of 0-5%. In contrast to many existing studies, our results clearly demonstrate that scatter-hoarding rodents prefer slightly 'astringent' food. In the co-evolutionary arms race between plants and animals, our results suggest that while tannins may play a significant role in reducing general predation levels by the faunal community, they have no precise control over the behavior of their mutualistic partner. Instead, the two partners appear to have reached an evolutionary point where both parties receive adequate benefits, with the year-to-year outcome being dependent on a wide range of factors beyond the control of either partner. PMID:22046284

Wang, Bo; Chen, Jin

2011-01-01

93

Tropical Severe Local Storms  

NSDL National Science Digital Library

The module provides a brief overview of severe local storms in the tropics. Basic ingredients for thunderstorms and assessment of thunderstorm potential from soundings are described. Then properties and hazards of ordinary thunderstorms, multicellular thunderstorms, supercells are reviewed. Conditions conducive to supercell formation in the tropics are examined along with methods of identifying them in radar and satellite images. Supercell and non-supercell tornado properties and formation are described. Finally, tornadoes, waterspouts, and dust devils properties are compared.

COMET

2013-01-09

94

Tolerance in the Tropics  

NSDL National Science Digital Library

Although temperatures are predicted to rise the most in northern latitudes due to global warming, tropical plants and animals might have the most difficult time adapting to climate change. This radio broadcast explains how temperature varies by only a couple of degrees annually in the tropics, and organisms there have a narrow range of temperature tolerance. The clip is 2 minutes in length and is available in MP3 format.

Katt-Reinders, Elizabeth

95

Domestic Rodent Control Training Manual: A Training Aid for the Rodent Control Category for Certification of Pesticide Applicators.  

ERIC Educational Resources Information Center

This training manual, designed for training applicants who wish to obtain certification in pesticide application relative to rodent control, covers the following topics: economic factors, public health factors, biological characteristics of domestic rodents, rat and mouse signs, trapping, repellents, poisons, baits, poisoned water, dumps, sewers,…

Childress, William R., Jr.; And Others

96

Guidelines for Euthanasia of Rodents Using Carbon Dioxide Rodents must be euthanized by trained personnel using appropriate technique, equipment and  

E-print Network

1 Guidelines for Euthanasia of Rodents Using Carbon Dioxide Rodents must be euthanized by trained in cylinders is the only recommended source of carbon dioxide as it allows the inflow of gas to the induction USP Grade A (medical) or Grade B (industrial) carbon dioxide may be considered acceptable as they each

Bandettini, Peter A.

97

Intraoperative cerebral blood flow imaging of rodents  

NASA Astrophysics Data System (ADS)

Intraoperative monitoring of cerebral blood flow (CBF) is of interest to neuroscience researchers, which offers the assessment of hemodynamic responses throughout the process of neurosurgery and provides an early biomarker for surgical guidance. However, intraoperative CBF imaging has been challenging due to animal's motion and position change during the surgery. In this paper, we presented a design of an operation bench integrated with laser speckle contrast imager which enables monitoring of the CBF intraoperatively. With a specially designed stereotaxic frame and imager, we were able to monitor the CBF changes in both hemispheres during the rodent surgery. The rotatable design of the operation plate and implementation of online image registration allow the technician to move the animal without disturbing the CBF imaging during surgery. The performance of the system was tested by middle cerebral artery occlusion model of rats.

Li, Hangdao; Li, Yao; Yuan, Lu; Wu, Caihong; Lu, Hongyang; Tong, Shanbao

2014-09-01

98

[Neurosteroidogenesis and exploratory responses in rodents].  

PubMed

We have studied the influence of intraperitoneal introduction of a selective blocker of mitochondrial translocation protein 18kD PK11195 (5 mg/kg), indomethacin (5 and 10 mg/kg), finasteride (5 and 15 mg/kg), and neurosteroid pregnenolone (20 mg/kg) on the exploratory behavior of male BALB/c mice, C57BL/6 mice, and Wistar rats in open-field test. It is found that treatment with PK11195 weakens the exploratory behavior in open-field test in mice of both strains. Finasteride and indomethacin decrease the exploratory responses in rodents regardless of the species or type of stress emotional response phenotype. Pregnenolone possesses activating effect in open-field in open-field test, but enhances the inhibitory effect of finasteride in BALB/c mice. PMID:24791332

Kalinina, T S; Shimshirt, A A; Kudriashov, N V; Voronina, T A; Seredenin, S B

2014-01-01

99

[Research in tropical medicine].  

PubMed

In France, research in tropical medicine is carried out by the Institute for Research and Development (IRD), university-affiliated institutes, and other research organizations such as INSERM, CNRS and the Pasteur Institute. Currently, this research is highly fragmented and therefore inefficient. As a result, despite significant financial means, French research in this field is not sufficiently competitive. This research activity should be coordinated by creating a "federation ", that would 1) facilitate the sharing of material and human resources, thereby improving efficiency and resulting in cost savings; 2) valorize French research in tropical medicine and its expert know-how, thus favoring the nomination of French experts in large international research programs (French experts in tropical medicine are currently under-recognized); 3) attract young researchers from France and elsewhere; and 4) adapt to the ongoing demographic and economic evolution of tropical countries. The creation of a Federation of French researchers would also make research in tropical medicine more visible. The objectives to which it leads already must include 1) a better understanding of the priorities of countries in the southern hemisphere, taking into account the social, cultural and economic contexts and ensuring the consistency of current and future projects ; 2) strengthening of research networks in close and equal partnership with researchers in the southern hemisphere, with pooling of resources (scientific, human and material) to reach the critical mass required for major projects ; 3) promoting the emergence of centers of excellence for health research in tropical countries ; and 4) contributing more effectively to training, because there can be no training without research, and no research without training This consolidation will help to empower research in tropical medicine, as in other Western countries, and will allow France to recover the place it deserves. The specific conditions of this Federation of all French stakeholders (universities, research institutes, the military, and NGOs) must be defined by a committee of elected or nominated officials. PMID:25796729

Dumas, Michel; Preux, Pierre-Marie

2013-10-01

100

Structural insights into the rodent CNS via diffusion tensor imaging  

PubMed Central

Diffusion tensor imaging (DTI) is a useful tool for studying anatomy and pathology in the rodent central nervous system (CNS).The unique tissue contrasts provided by DTI are well suited for monitoring disease progression, studying brain development, and characterizing anatomical phenotypes. Recent technical developments have vastly improved the speed and resolution of rodent DTI. Ongoing research efforts exploring the microstructural basis of DTI signals have provided useful insights into its capabilities to delineate brain structures and detect neuropathology. Significant progress has also been made in combining DTI results with data acquired using other imaging modalities to enhance our understanding of the rodent CNS. PMID:22651954

Zhang, Jiangyang; Aggarwal, Manisha; Mori, Susumu

2012-01-01

101

Lack of seroreactivity to Ehrlichia chaffeensis among rodent populations.  

PubMed

A retrospective serosurvey for antibodies to Ehrlichia chaffeensis was conducted on eight species of wild rodents (Mus musculus, Oryzomys palustris, Peromyscus leucopus, Rattus norvegicus, Reithrodontomys humulis, Sciurus carolinensis, Sciurus niger, and Sigmodon hispidus) from the southeastern United States. Serum samples (n = 281) collected between 1973 and 1993 were evaluated using an indirect fluorescent antibody test. All samples, screened at a dilution of 1:32, were negative for antibodies to E. chaffeensis. Sixty-three percent of the rodents tested were from areas where E. chaffeensis has been confirmed or is strongly suspected to be endemic. These data suggest limited or no involvement of rodents in the epidemiology of E. chaffeensis. PMID:9577793

Lockhart, J M; Davidson, W R; Stallknecht, D E; Dawson, J E

1998-04-01

102

New Building, Old Parasite: Mesostigmatid Mites—An Ever-Present Threat to Barrier Rodent Facilities  

Microsoft Academic Search

Mesostigmatid mites are blood-sucking parasitic mites found in wild rodent populations. Periodically they can also become a problem for laboratory rodent colonies, particu- larly when building construction or renovations disturb colonies of commensal (building) rodents that had been act- ing as hosts. Mesostigmatid mites infest both rats and mice and, unlike the more common rodent fur mites (Myobia, Myocoptes, and

Julie Watson

103

Tropical rainforest biodiversity: field and  

E-print Network

Tropical rainforest biodiversity: field and GIS tools for assessing, monitoring and mapping II. Francesco Rovero, Curator, (tropical biodiversity and forest mammal expert) and Dr. Clara Tattoni, Research international biodiversity experts will teach specific modules. In collaboration with: Further information

104

Tropical cyclone formation  

SciTech Connect

The physics of tropical cyclone formation is not well understood, and more is known about the mature hurricane than the formative mechanisms that produce it. It is believed part of the reason for this can be traced to insufficient upper-level atmospheric data. Recent observations suggest that tropical cyclones are initiated by asymmetric interactions associated with migratory upper-level potential vorticity disturbances and low-level disturbances. Favored theories of cyclones formation, however, focus on internal processes associated with cumulus convection and/or air-sea interaction. This work focuses on external mechanisms of cyclone formation and, using both a two- and three-dimensional moist geostrophic momentum model, investigates the role of upper-level potential vorticity disturbances on the formation process. A conceptual model of tropical cyclone formation is proposed, and implications of the theory are discussed. 71 refs., 5 figs., 1 tab.

Montgomery, M.T.; Farrell, B.F. (Harvard Univ., Cambridge, MA (United States))

1993-01-15

105

Tropical Cyclone Climatology  

NSDL National Science Digital Library

This site contains figures and tables that describe the progress of a typical hurricane season in terms of the total number of tropical systems and hurricanes produced throughout the year in the Atlantic and East Pacific basins. The figures have curves which represent the average cumulative production of all named tropical systems, all hurricanes, and those hurricanes which were Category 3 or stronger in those basins. The tables list benchmark dates when a given number of tropical systems, hurricanes, or category 3 storms should have been generated. In the progress of the average Atlantic or East Pacific season based on 1944-1996 data, they show the date upon which the number of events would normally have occurred.

106

Can Rodent Longevity Studies be Both Short and Powerful?  

PubMed Central

Many rodent experiments have assessed effects of diets, drugs, genes, and other factors on life span. A challenge with such experiments is their long duration, typically over 3.5 years given rodent life spans, thus requiring significant time costs until answers are obtained. We collected longevity data from 15 rodent studies and artificially truncated them at 2 years to assess the extent to which one will obtain the same answer regarding mortality effects. When truncated, the point estimates were not significantly different in any study, implying that in most cases, truncated studies yield similar estimates. The median ratio of variances of coefficients for truncated to full-length studies was 3.4, implying that truncated studies with roughly 3.4 times as many rodents will often have equivalent or greater power. Cost calculations suggest that shorter studies will be more expensive but perhaps not so much to not be worth the reduced time. PMID:21051569

Robertson, Henry T.; Smith, Daniel L.; Pajewski, Nicholas M.; Weindruch, Richard H.; Garland, Theodore; Argyropoulos, George; Bokov, Alex

2011-01-01

107

A NEW METHOD TO QUANTIFY CORE TEMPERATURE INSTABILITY IN RODENTS.  

EPA Science Inventory

Methods to quantify instability of autonomic systems such as temperature regulation should be important in toxicant and drug safety studies. Stability of core temperature (Tc) in laboratory rodents is susceptible to a variety of stimuli. Calculating the temperature differential o...

108

Page 1 of 12 Veterinary Medical Treatment of Rodents  

E-print Network

Rectal Prolapse ............... 7 Cage Checking ............. 1 Severe Tail Bite Wounds ... 5 Eye Lesions ....................... 2 NOTE: All rodents with skin lesions, eye lesions, rectal prolapses or fight wounds must be treated

Wlodawer, Alexander

109

ASSESSMENT OF HOST RESISTANCE TO INFECTION WITH RODENT MALARIA  

EPA Science Inventory

Resistance to malaria infection is known to require an intact immune system. his chapter presents an overview of rodent malaria, the host response to infection and methods for assessing infection in rats and mice....

110

Neural Representation of Spatial Topology in the Rodent Hippocampus  

E-print Network

Pyramidal cells in the rodent hippocampus often exhibit clear spatial tuning in navigation. Although it has been long suggested that pyramidal cell activity may underlie a topological code rather than a topographic code, ...

Chen, Zhe

111

Allocentric directional processing in the rodent and human retrosplenial cortex  

PubMed Central

Head direction (HD) cells in the rodent brain have been investigated for a number of years, providing us with a detailed understanding of how the rodent brain codes for allocentric direction. Allocentric direction refers to the orientation of the external environment, independent of one’s current (egocentric) orientation. The presence of neural activity related to allocentric directional coding in humans has also been noted but only recently directly tested. Given the current status of both fields, it seems beneficial to draw parallels between this rodent and human research. We therefore discuss how findings from the human retrosplenial cortex (RSC), including its “translational function” (converting egocentric to allocentric information) and ability to code for permanent objects, compare to findings from the rodent RSC. We conclude by suggesting critical future experiments that derive from a cross-species approach to understanding the function of the human RSC. PMID:24672459

Knight, Rebecca; Hayman, Robin

2014-01-01

112

Galanin impairs cognitive abilities in rodents: relevance to Alzheimers Disease  

E-print Network

Galanin impairs cognitive abilities in rodents: relevance to Alzheimers Disease J. N. Crawley Laboratory of Behavioral Neuroscience, National Institute of Mental Health, Porter Neuroscience Research processes, taken together with the overexpression of galanin in Alzheimers disease, suggests that galanin

113

MEASUREMENT OF VENTILATORY FREQUENCY IN UNRESTRAINED RODENTS USING MICROWAVE RADIATION  

EPA Science Inventory

A novel technique for remote determination of breathing frequency in unrestrained rodents using microwave radiation is described. Single mice were placed inside a rectangular waveguide operating at 2450 MHz. Because mice efficiently absorb radio frequency energy at 2450 MHz, any ...

114

Swimming ability in three Costa Rican dry forest rodents  

E-print Network

We investigated the swimming abilities of three Costa Rican dry forest rodents (Coues' rice rat. Oryzomys couesi, hispid cotton rat, Sigmodon hispidus, and spiny pocket mouse, Liomys salvini) associated with a large marsh, Laguna Palo Verde, using...

Cook, William M.; Timm, Robert M.; Hymen, Dena E.

2001-12-01

115

Dual captures of Colorado rodents: implications for transmission of hantaviruses.  

PubMed Central

We analyzed dual-capture data collected during longitudinal studies monitoring transmission and persistence of Sin Nombre virus in rodents in Colorado. Our data indicate that multiple captures (two or more rodents captured in a single trap) may not be random, as indicated by previous studies, but rather the result of underlying, species-specific social behavior or cohesiveness. In the pairs we captured, most often, rodents were of the same species, were male, and could be recaptured as pairs. Therefore, dual captures of rodents, which are unusual but not rare, tend to occur among certain species, and appear to be nonrandom, group-foraging encounters. These demographic and ecologic characteristics may have implications for the study of the transmission of hantaviruses. PMID:10970147

Calisher, C. H.; Childs, J. E.; Sweeney, W. P.; Canestrop, K. M.; Beaty, B. J.

2000-01-01

116

Edinburgh Research Explorer Functional conservation between rodents and chicken of  

E-print Network

Edinburgh Research Explorer Functional conservation between rodents and chicken of regulatory sequences driving skeletal muscle gene expression in transgenic chickens Citation for published version: Mc and chicken of regulatory sequences driving skeletal muscle gene expression in transgenic chickens' BMC

Millar, Andrew J.

117

The tropical totally positive Grassmannian  

Microsoft Academic Search

Tropical algebraic geometry is the geometry of the tropical semiring (R, min, +). The theory of total positivity is a natural generalization of the study of matrices with all minors positive. In this paper we introduce the totally positive part of the tropicalization of an arbitrary affine variety, an object which has the structure of a polyhedral fan. We then

David Speyer; Lauren K. Williams

2003-01-01

118

Tropical Rainfall Measuring Mission  

NASA Technical Reports Server (NTRS)

Tropical rainfall affects the lives and economics of a majority of the Earth's population. Tropical rain systems, such as hurricanes, typhoons, and monsoons, are crucial to sustaining the livelihoods of those living in the tropics. Excess rainfall can cause floods and great property and crop damage, whereas too little rainfall can cause drought and crop failure. The latent heat release during the process of precipitation is a major source of energy that drives the atmospheric circulation. This latent heat can intensify weather systems, affecting weather thousands of kilometers away, thus making tropical rainfall an important indicator of atmospheric circulation and short-term climate change. Tropical forests and the underlying soils are major sources of many of the atmosphere's trace constituents. Together, the forests and the atmosphere act as a water-energy regulating system. Most of the rainfall is returned to the atmosphere through evaporation and transpiration, and the atmospheric trace constituents take part in the recycling process. Hence, the hydrological cycle provides a direct link between tropical rainfall and the global cycles of carbon, nitrogen, and sulfur, all important trace materials for the Earth's system. Because rainfall is such an important component in the interactions between the ocean, atmosphere, land, and the biosphere, accurate measurements of rainfall are crucial to understanding the workings of the Earth-atmosphere system. The large spatial and temporal variability of rainfall systems, however, poses a major challenge to estimating global rainfall. So far, there has been a lack of rain gauge networks, especially over the oceans, which points to satellite measurement as the only means by which global observation of rainfall can be made. The Tropical Rainfall Measuring Mission (TRMM), jointly sponsored by the National Aeronautics and Space Administration (NASA) of the United States and the National Space Development Agency (NASDA) of Japan, provides visible, infrared, and microwave observations of tropical and subtropical rain systems.The satellite observations are complemented by ground radar and rain gauge measurements to validate satellite rain estimation techniques. Goddard Space Flight Center's involvement includes the observatory, four instruments, integration and testing of the observatory, data processing and distribution, and satellite operations. TRMM has a design lifetime of three years. Data generated from TRMM and archived at the GDAAC are useful not only for hydrologists, atmospheric scientists, and climatologists, but also for the health community studying infectious diseases, the ocean research community, and the agricultural community.

1999-01-01

119

Tropical Mesoscale Convective Systems  

NSDL National Science Digital Library

Mesoscale Convective Systems (MCSs) occur globally and can account for significant percentages of the annual precipitation in some locations. MCSs are responsible for flooding as well as damaging surface winds in some instances. Thus, it is important for forecasters to understand when, where, and how MCSs develop and maintain themselves. This module covers all modes of MCSs with a strong focus on the tropics and the different aspects that brings to MCS development, maintenance, and structure. It describes conceptual models of MCSs and the dynamical and physical processes that influence their evolution. Also included are examples of MCSs from various areas of the tropics.

COMET

2013-05-14

120

Acidification in tropical countries  

SciTech Connect

Acidification of the environment--caused by the emission of sulfur and nitrogen oxides into the atmosphere--is one of the most serious side effects of industrialization. This volume provides a thorough introduction to this global problem. A basic overview describes acidification processes occurring in the air, water, and soil, and relates other facts known about the acidification of the tropical environment. There is discussion of potential future impacts of emissions which cause acidification. Includes a series of case studies focusing on acidification problems in specific countries in the tropics.

Rodhe, H.; Herrera, R.

1988-01-01

121

The Pathogenesis of Alopecia Areata in Rodent Models  

Microsoft Academic Search

Rodent models of human disease provide an important tool in the investigation of genetic and environmental activation factors, disease pathogenesis, and the development of new and improved treatments. Up to 20% of aged C3H\\/HeJ mice and 70% of Dundee Experimental Bald Rats (DEBR) develop alopecia areata (AA), a nonscarring, inflammatory hair loss disease with a suspected autoimmune pathogenesis. These rodent

Kevin J. McElwee; Pia Freyschmidt-Paul; John P. Sundberg; Rolf Hoffmann

2003-01-01

122

Findings of mycobacteria in insectivores and small rodents  

Microsoft Academic Search

The organs of 30 insectivorous mammals and 62 rodents from areas inhabited by people or livestock where cattle paratuberculosis\\u000a or mycobacterial infections of swine had been found to occur were examined by cultivation during the monitoring of occurrence\\u000a and spread of mycobacterioses in cattle and swine. Mycobacteria were found in the organs of 3 insectivores (10%) and 6 rodents\\u000a (9.7%).Mycobacterium

O. Fischer; L. Mátlová; J. Bartl; L. Dvorská; I. Melichárek; I. Pavlík

2000-01-01

123

Secondary dispersal of Dioscorea japonica (Dioscoreaceae) bulbils by rodents  

Microsoft Academic Search

We examined rodent dispersal of Dioscorea japonica bulbils. Bulbils dispersed by rodents may travel farther from their parent plants than those dispersed by gravity alone.\\u000a To confirm the presence of secondary dispersal and the types of vector, we used an automatic camera to photograph animals\\u000a that approached bulbils. To clarify secondary dispersal distance, we set marked bulbils at eight sites

Inoue Mizuki; Akiko Takahashi

2009-01-01

124

Calcimimetics inhibit renal pathology in rodent nephronophthisis.  

PubMed

The development and progression of renal cysts appears to be driven by reduced cellular calcium and increased cyclic adenosine monophosphate (cAMP) from G-protein-coupled receptors. To test whether treatment with a calcimimetic that stimulates the G-protein-coupled calcium-sensing receptor might normalize cystic epithelial cell intracellular calcium and cAMP, thereby inhibiting cyst progression, we used pcy mice. These animals develop cysts principally in the collecting duct, as do humans with nephronophthisis (NPHP). We administered the calcimimetic R-568 mixed in their food at early or late stages in the pathogenesis of cyst formation. The treatment reduced cyst enlargement, and the early treatment inhibited development of renal fibrosis. Although the effect of later treatment was more modest, both stages of the disease responded positively to treatment. Additionally, R-568 decreased total kidney cAMP in the pcy mice and, in vitro, decreased cAMP levels and cell proliferation, while increasing intracellular calcium in immortalized human autosomal recessive polycystic kidney disease renal epithelial cells. The latter two effects were unique to R-568 and not replicated by raising extracellular calcium. Thus, treating pcy mice with R-568 was effective in reducing cyst progression in this rodent model of NPHP. Direct studies will be needed to determine whether these results can be applied to the human disease. PMID:21633408

Chen, Neal X; Moe, Sharon M; Eggleston-Gulyas, Tracy; Chen, Xianming; Hoffmeyer, William D; Bacallao, Robert L; Herbert, Brittney S; Gattone, Vincent H

2011-09-01

125

Widespread vestibular activation of the rodent cortex.  

PubMed

Much of our understanding of the neuronal mechanisms of spatial navigation is derived from chronic recordings in rodents in which head-direction, place, and grid cells have all been described. However, despite the proposed importance of self-reference information to these internal representations of space, their congruence with vestibular signaling remains unclear. Here we have undertaken brain-wide functional mapping using both fMRI and electrophysiological methods to directly determine the spatial extent, strength, and time course of vestibular signaling across the rat forebrain. We find distributed activity throughout thalamic, limbic, and particularly primary sensory cortical areas in addition to known head-direction pathways. We also observe activation of frontal regions, including infralimbic and cingulate cortices, indicating integration of vestibular information throughout functionally diverse cortical regions. These whole-brain activity maps therefore suggest a widespread contribution of vestibular signaling to a self-centered framework for multimodal sensorimotor integration in support of movement planning, execution, spatial navigation, and autonomic responses to gravito-inertial changes. PMID:25878265

Rancz, Ede A; Moya, Javier; Drawitsch, Florian; Brichta, Alan M; Canals, Santiago; Margrie, Troy W

2015-04-15

126

Active vibrissal sensing in rodents and marsupials  

PubMed Central

In rats, the long facial whiskers (mystacial macrovibrissae) are repetitively and rapidly swept back and forth during exploration in a behaviour known as ‘whisking’. In this paper, we summarize previous evidence from rats, and present new data for rat, mouse and the marsupial grey short-tailed opossum (Monodelphis domestica) showing that whisking in all three species is actively controlled both with respect to movement of the animal's body and relative to environmental structure. Using automatic whisker tracking, and Fourier analysis, we first show that the whisking motion of the mystacial vibrissae, in the horizontal plane, can be approximated as a blend of two sinusoids at the fundamental frequency (mean 8.5, 11.3 and 7.3 Hz in rat, mouse and opossum, respectively) and its second harmonic. The oscillation at the second harmonic is particularly strong in mouse (around 22 Hz) consistent with previous reports of fast whisking in that species. In all three species, we found evidence of asymmetric whisking during head turning and following unilateral object contacts consistent with active control of whisker movement. We propose that the presence of active vibrissal touch in both rodents and marsupials suggests that this behavioural capacity emerged at an early stage in the evolution of therian mammals. PMID:21969685

Mitchinson, Ben; Grant, Robyn A.; Arkley, Kendra; Rankov, Vladan; Perkon, Igor; Prescott, Tony J.

2011-01-01

127

Assessing Spatial Learning and Memory in Rodents  

PubMed Central

Maneuvering safely through the environment is central to survival of almost all species. The ability to do this depends on learning and remembering locations. This capacity is encoded in the brain by two systems: one using cues outside the organism (distal cues), allocentric navigation, and one using self-movement, internal cues and nearby proximal cues, egocentric navigation. Allocentric navigation involves the hippocampus, entorhinal cortex, and surrounding structures; in humans this system encodes allocentric, semantic, and episodic memory. This form of memory is assessed in laboratory animals in many ways, but the dominant form of assessment is the Morris water maze (MWM). Egocentric navigation involves the dorsal striatum and connected structures; in humans this system encodes routes and integrated paths and, when overlearned, becomes procedural memory. In this article, several allocentric assessment methods for rodents are reviewed and compared with the MWM. MWM advantages (little training required, no food deprivation, ease of testing, rapid and reliable learning, insensitivity to differences in body weight and appetite, absence of nonperformers, control methods for proximal cue learning, and performance effects) and disadvantages (concern about stress, perhaps not as sensitive for working memory) are discussed. Evidence-based design improvements and testing methods are reviewed for both rats and mice. Experimental factors that apply generally to spatial navigation and to MWM specifically are considered. It is concluded that, on balance, the MWM has more advantages than disadvantages and compares favorably with other allocentric navigation tasks. PMID:25225309

Vorhees, Charles V.; Williams, Michael T.

2014-01-01

128

Hindlimb unloading rodent model: technical aspects  

NASA Technical Reports Server (NTRS)

Since its inception at the National Aeronautics and Space Administration (NASA) Ames Research Center in the mid-1970s, many laboratories around the world have used the rat hindlimb unloading model to simulate weightlessness and to study various aspects of musculoskeletal loading. In this model, the hindlimbs of rodents are elevated to produce a 30 degrees head-down tilt, which results in a cephalad fluid shift and avoids weightbearing by the hindquarters. Although several reviews have described scientific results obtained with this model, this is the first review to focus on the technical aspects of hindlimb unloading. This review includes a history of the technique, a brief comparison with spaceflight data, technical details, extension of the model to mice, and other important technical considerations (e.g., housing, room temperature, unloading angle, the potential need for multiple control groups, age, body weight, the use of the forelimb tissues as internal controls, and when to remove animals from experiments). This paper is intended as a reference for researchers, reviewers of manuscripts, and institutional animal care and use committees. Over 800 references, related to the hindlimb unloading model, can be accessed via the electronic version of this article.

Morey-Holton, Emily R.; Globus, Ruth K.

2002-01-01

129

Rodent models of neuroinflammation for Alzheimer's disease.  

PubMed

Alzheimer's disease remains incurable, and the failures of current disease-modifying strategies for Alzheimer's disease could be attributed to a lack of in vivo models that recapitulate the underlying etiology of late-onset Alzheimer's disease. The etiology of late-onset Alzheimer's disease is not based on mutations related to amyloid-? (A?) or tau production which are currently the basis of in vivo models of Alzheimer's disease. It has recently been suggested that mechanisms like chronic neuroinflammation may occur prior to amyloid-? and tau pathologies in late-onset Alzheimer's disease. The aim of this study is to analyze the characteristics of rodent models of neuroinflammation in late-onset Alzheimer's disease. Our search criteria were based on characteristics of an idealistic disease model that should recapitulate causes, symptoms, and lesions in a chronological order similar to the actual disease. Therefore, a model based on the inflammation hypothesis of late-onset Alzheimer's disease should include the following features: (i) primary chronic neuroinflammation, (ii) manifestations of memory and cognitive impairment, and (iii) late development of tau and A? pathologies. The following models fit the pre-defined criteria: lipopolysaccharide- and PolyI:C-induced models of immune challenge; streptozotocin-, okadaic acid-, and colchicine neurotoxin-induced neuroinflammation models, as well as interleukin-1?, anti-nerve growth factor and p25 transgenic models. Among these models, streptozotocin, PolyI:C-induced, and p25 neuroinflammation models are compatible with the inflammation hypothesis of Alzheimer's disease. PMID:25890375

Nazem, Amir; Sankowski, Roman; Bacher, Michael; Al-Abed, Yousef

2015-01-01

130

Divergent patterns of breakpoint reuse in Muroid rodents.  

PubMed

Multiple Genome Rearrangement (MGR) analysis was used to define the trajectory and pattern of chromosome rearrangement within muroid rodents. MGR was applied using 107 chromosome homologies between Mus, Rattus, Peromyscus, the muroid sister taxon Cricetulus griseus, and Sciurus carolinensis as a non-Muroidea outgroup, with specific attention paid to breakpoint reuse and centromere evolution. This analysis revealed a high level of chromosome breakpoint conservation between Rattus and Peromyscus and indicated that the chromosomes of Mus are highly derived. This analysis identified several conserved evolutionary breakpoints that have been reused multiple times during karyotypic evolution in rodents. Our data demonstrate a high level of reuse of breakpoints among muroid rodents, further supporting the "Fragile Breakage Model" of chromosome evolution. We provide the first analysis of rodent centromeres with respect to evolutionary breakpoints. By analyzing closely related rodent species we were able to clarify muroid rodent karyotypic evolution. We were also able to derive several high-resolution ancestral karyotypes and identify rearrangements specific to various stages of Muroidea evolution. These data were useful in further characterizing lineage-specific modes of chromosome evolution. PMID:20033182

Mlynarski, E E; Obergfell, C J; O'Neill, M J; O'Neill, R J

2010-02-01

131

People & Tropical Rain Forests.  

ERIC Educational Resources Information Center

Discusses ways people who live in rain forests make a living and some of the products that enrich our lives. Provides activities covering forest people, tropical treats, jungle in the pantry, treetop explorers, and three copyable pages to accompany activities. (Author/RT)

NatureScope, 1989

1989-01-01

132

Neglected tropical disease vaccines  

Microsoft Academic Search

The neglected tropical diseases or ‘NTDs’ represent the most common infections of the world's one billion poorest people. Unlike the better known acute or emerging infections, the NTDs are generally chronic and disabling (and often disfiguring) conditions. The long-term disability they cause has been revealed as a major reason why poor people in developing countries cannot escape the poverty trap.

Peter J. Hotez; Ami Shah Brown

2009-01-01

133

Tropical Cyclones John, Steve  

E-print Network

active, with a total of eight tropical cyclones detected in waters off northwest Australia (the waters hours with a maximum gust of 210 km/h (data courtesy of Robe River Iron Ore Automatic Weather Station of Cairns as a category 2 system on 27 February and weakened. The

Greenslade, Diana

134

Rain Forests: Tropical Treasures.  

ERIC Educational Resources Information Center

Ranger Rick's NatureScope is a creative education series dedicated to inspiring in children an understanding and appreciation of the natural world while developing the skills they will need to make responsible decisions about the environment. The topic of this issue is "Rain Forests: Tropical Treasures." Contents are organized into the following…

Braus, Judy, Ed.

1989-01-01

135

Tropical Atlantic Aerosols  

NSDL National Science Digital Library

Students will use real satellite data to determine 1) where the greatest concentrations of aerosols are located during the course of a year in the tropical Atlantic region and 2) their source of origin. This is an inquiry-style lesson where students pull real aerosol data and attempt to identify trends among data sets.

Rex Roettger

136

Tropical Storm Cristobal  

NSDL National Science Digital Library

This animation shows Tropical Storm Cristobal on August 7, 2002 . Cristobal was located east of St. Augustine, Florida. The storm has had a maximum sustained wind speed of 45 MPH.Cristobal is expected to move east-northeast within the next 24 hours.

Lori Perkins

2002-08-07

137

Assessing Tropical Cyclone Damage  

NASA Astrophysics Data System (ADS)

Landfalling tropical cyclones impact large coastal and inland areas causing direct damage due to winds, storm-surge flooding, tornadoes, and precipitation; as well as causing substantial indirect damage such as electrical outages and business interruption. The likely climate change impact of increased tropical cyclone intensity, combined with increases in exposure, bring the possibility of increased damage in the future. A considerable amount of research has focused on modeling economic damage due to tropical cyclones, and a series of indices have been developed to assess damages under climate change. We highlight a number of ways this research can be improved through a series of case study analyses. First, historical loss estimates are revisited to properly account for; time, impacted regions, the source of damage by type, and whether the damage was direct/indirect and insured/uninsured. Second, the drivers of loss from both the socio-economic and physical side are examined. A case is made to move beyond the use of maximum wind speed to more stable metrics and the use of other characteristics of the wind field such as direction, degree of gustiness, and duration is explored. A novel approach presented here is the potential to model losses directly as a function of climate variables such as sea surface temperature, greenhouse gases, and aerosols. This work is the first stage in the development of a tropical cyclone loss model to enable projections of losses under scenarios of both socio-economic change (such as population migration or altered policy) and physical change (such as shifts in tropical cyclone activity one from basin to another or within the same basin).

Done, J.; Czajkowski, J.

2012-12-01

138

Partial Rodent Genetic Models for Bipolar Disorder  

PubMed Central

Bipolar disorder (BPD) is a complex clinical phenomenon. This episodic illness comprises at least four features/components: depression, mania, vulnerability to mood swings in euthymic BPD patients, and spontaneous cyclicity in at least some BPD patients. Currently, there is no rodent genetic model capable of encompassing the whole phenotype of BPD exists; however, recent genetic-behavioral studies have delineated partial models for some components of BPD, namely, depression, mania, and vulnerability or resilience to mood swings. p11 knockout (KO), vesicular monoamine transporter 2 (VMAT2) heterozygous KO, and neural cell adhesion molecule (NCAM) KO mice display anhedonia-like symptoms, and treatment with antidepressants rescues this anhedonia-related phenotype. Mutant CLOCK, glutamate receptor 6 (GluR6) KO, and extracellular signal-regulated kinase 1 (ERK1) KO mice exhibit mania-like behavioral clusters referred to as excessive behavioral excitement; at least some of the exhibited behaviors can be rescued through treatment with mood stabilizers or atypical antipsychotics. Neuronal glucocorticoid receptor (GR) overexpressing, B-cell lymphoma 2 (Bcl-2) heterozygous KO, and Bcl-2-associated athanogene (BAG1) heterozygous KO mice show vulnerability to mood swings. In contrast, neuronal BAG1 overexpressing mice display resilience to mood swings. These mutant mouse strains and the behavioral approaches used to characterize these strains offer an emerging set of research tools for the comprehensive understanding of various components of BPD, and the interrelation of these components at the molecular, cellular, and neuronal circuitry levels. These partial genetic models can also be used as complementary tools to augment other existing behavioral tests and paradigms in drug development for BPD. PMID:25236551

Chen, Guang; Henter, Ioline D.; Manji, Husseini K.

2015-01-01

139

Ectoparasites of Rodents Captured in Bandar Abbas, Southern Iran  

PubMed Central

Background: Rodents play important role as host of ectoparasites and reservoir of different zoonotic diseases. The aim of this study was to asses the infestation of commensal rodents with ectoparasites in Bandar Abbas, a port city located in the northern part of the Persian Gulf in Iran. Methods: Rodents were captured using live traps during the study period in year 2007. After transferring the rodents to the laboratory, they were identified and then their ectoparasites were collected and mounted for species identification using appropriate systematic keys. Results: A total of 77 rodents were identified including Rattus norvegicus (74%), R. rattus (16.9%), Mus musculus (7.8%) and one hamster. Among all rodents, 40.3% were found infested with ectoparasites. A total of 69 ectoparasites were collected comprising flea, lice, mite and tick. Two species of fleas; Xenopsylla cheopis and X. astia were identified with higher index of X. astia. Two genera of ticks including Hyalomma sp. and Rhipicephalus sp. were identified. Laelaps nuttalli was the only mite found. The Polyplax spinulosa was considered as lice ectoparasite. Conclusion: Among all arthropods collected, flea and lice had the most and the least frequency, respectively. Nearly all rodent species were infested with Xenopsylla. These fleas are important due to their role in plague and murine typhus transmission. Ticks are important due to their role in CCHF (Crimean-Congo Hemorrhagic Fever), theileriosis, babesiosis, anaplasmosis and ehrlichiosis transmission .Monitoring of ectoparaiste infestation is important for preparedness and early warning preparation for possible control of arthropod-borne diseases. PMID:22808381

Kia, EB; Moghddas-Sani, H; Hassanpoor, H; Vatandoost, H; Zahabiun, F; Akhavan, AA; Hanafi-Bojd, AA; Telmadarraiy, Z

2009-01-01

140

Interval eigenproblem in tropical and fuzzy algebra Tolerance eigenproblem in tropical algebra  

E-print Network

Interval eigenproblem in tropical and fuzzy algebra Tolerance eigenproblem in tropical algebra Tolerance eigenproblem in fuzzy algebra Tolerance interval eigenvectors in tropical and fuzzy algebra Martin Workshop Birmingham, May 16, 2013 #12;Interval eigenproblem in tropical and fuzzy algebra Tolerance

Mitchener, Paul

141

Tropical cyclone genesis across palaeoclimates  

NASA Astrophysics Data System (ADS)

Tropical cyclone genesis is investigated for the Pliocene, Last Glacial Maximum (LGM) and the mid-Holocene through analysis of five climate models. The genesis potential index is used to estimate this from large scale atmospheric properties. The mid-Pliocene and LGM characterise periods where carbon dioxide levels were higher and lower than pre-industrial respectively, while the mid-Holocene differed primarily in its orbital configuration. The number of tropical cyclones formed each year is found to be fairly consistent across the various palaeoclimates. Although there is some model uncertainty in the change of global annual tropical cyclone frequency, there are coherent changes in the spatial patterns of tropical cyclogenesis. During the Pliocene and LGM, changes in carbon dioxide led to sea surface temperature changes throughout the tropics, yet the potential intensity of tropical cyclones appears relatively insensitive to these variations. Changes in tropical cyclone genesis during the mid-Holocene are observed to be asymmetric about the Equator: genesis is reduced in the Northern Hemisphere, but enhanced in the Southern Hemisphere. This is clearly driven by the altered seasonal insolation. Nonetheless, the enhanced seasonality may have driven localised effects on tropical cyclone genesis, through changes to the strength of monsoons and shifting of the inter-tropical convergence zone. Trends in future tropical cyclone genesis are neither consistent between the five models studied, nor with the palaeoclimate results. It is not clear why this should be the case.

Koh, J. H.; Brierley, C. M.

2015-02-01

142

Identification of Rodent Homologs of Hepatitis C Virus and Pegiviruses  

PubMed Central

ABSTRACT Hepatitis C virus (HCV) and human pegivirus (HPgV or GB virus C) are globally distributed and infect 2 to 5% of the human population. The lack of tractable-animal models for these viruses, in particular for HCV, has hampered the study of infection, transmission, virulence, immunity, and pathogenesis. To address this challenge, we searched for homologous viruses in small mammals, including wild rodents. Here we report the discovery of several new hepaciviruses (HCV-like viruses) and pegiviruses (GB virus-like viruses) that infect wild rodents. Complete genome sequences were acquired for a rodent hepacivirus (RHV) found in Peromyscus maniculatus and a rodent pegivirus (RPgV) found in Neotoma albigula. Unique genomic features and phylogenetic analyses confirmed that these RHV and RPgV variants represent several novel virus species in the Hepacivirus and Pegivirus genera within the family Flaviviridae. The genetic diversity of the rodent hepaciviruses exceeded that observed for hepaciviruses infecting either humans or non-primates, leading to new insights into the origin, evolution, and host range of hepaciviruses. The presence of genes, encoded proteins, and translation elements homologous to those found in human hepaciviruses and pegiviruses suggests the potential for the development of new animal systems with which to model HCV pathogenesis, vaccine design, and treatment. PMID:23572554

Kapoor, Amit; Simmonds, Peter; Scheel, Troels K. H.; Hjelle, Brian; Cullen, John M.; Burbelo, Peter D.; Chauhan, Lokendra V.; Duraisamy, Raja; Sanchez Leon, Maria; Jain, Komal; Vandegrift, Kurt Jason; Calisher, Charles H.; Rice, Charles M.; Lipkin, W. Ian

2013-01-01

143

Geographical distribution of rodent-associated hantaviruses in Texas.  

PubMed

The purpose of this study was to increase our knowledge of the geographic distribution and natural host range of hantaviruses in Texas, southeastern New Mexico, and Mexico. Blood samples from 3,225 wild rodents, representing 34 species, were tested for hantavirus antibody (IgG), using an enzyme-linked immunosorbent assay. Hantavirus antibody was found in one or more rodents from each of 13 counties in Texas, Otero County in southeastern New Mexico, and Mexico State (central Mexico). The 133 antibody-positive rodents included seven Peromyscus species (P. attwateri, P. boylii, P. hylocetes, P. leucopus, P. maniculatis, P. melanotis, and P. pectoralis), Sigmodon hispidus, Oryzomys palustris, two Reithrodontomys species (R. fulvescens and R. megalotis), Neotoma albigula, and Perognathus merriami. This study provides further evidence that rodent-associated hantaviruses are geographically widely distributed in Texas. The discovery of antibody in P. hylocetes and P. melanotis is evidence that peromyscine rodents in Mexico are naturally associated with viruses belonging to the genus Hantavirus. PMID:11469186

Mantooth, S J; Milazzo, M L; Bradley, R D; Hice, C L; Ceballos, G; Tesh, R B; Fulhorst, C F

2001-06-01

144

Rodent Models of Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis  

PubMed Central

Research in nonalcoholic fatty liver disease (NAFLD), including nonalcoholic steatohepatitis (NASH), has been limited by the availability of suitable models for this disease. A number of rodent models have been described in which the relevant liver pathology develops in an appropriate metabolic context. These models are promising tools for researchers investigating one of the key issues of NASH: not so much why steatosis occurs, but what causes the transition from simple steatosis to the inflammatory, progressive fibrosing condition of steatohepatitis. The different rodent models can be classified into two large groups. The first includes models in which the disease is acquired after dietary or pharmacological manipulation, and the second, genetically modified models in which liver disease develops spontaneously. To date, no single rodent model has encompassed the full spectrum of human disease progression, but individual models can imitate particular characteristics of human disease. Therefore, it is important that researchers choose the appropriate rodent models. The purpose of the present review is to discuss the metabolic abnormalities present in the currently available rodent models of NAFLD, summarizing the strengths and weaknesses of the established models and the key findings that have furthered our understanding of the disease’s pathogenesis. PMID:24192824

Imajo, Kento; Yoneda, Masato; Kessoku, Takaomi; Ogawa, Yuji; Maeda, Shin; Sumida, Yoshio; Hyogo, Hideyuki; Eguchi, Yuichiro; Wada, Koichiro; Nakajima, Atsushi

2013-01-01

145

Tropical ecotoxicology: The state of the environment in the tropics  

SciTech Connect

Ecotoxicology has focused almost exclusively on temperate zone countries and ecosystems. Tropical ecosystems, including rain forest, tropical dry forest, savanna, wetlands and freshwater ecosystems, have been neglected. These ecosystems combined might contain as much as 75% of global biodiversity. Tropical ecosystems are under increasing threat of development and alteration. The major causes of habitat degradation in the tropics include population growth and urbanization, agricultural expansion, deforestation, and mining. Some of these activities (in particular agriculture, mining, and the manufacturing and chemical industries) also lead to the release of toxic substances into the environment. Little research in ecotoxicology has been done in tropical environments and techniques and procedures developed for temperate environments are often applied, even though physical and chemical environmental parameters in the tropics can be very different. The regulatory environment also varies from country to country. The authors present an extensive literature review of tropical ecotoxicology, with a focus on Latin America and the Caribbean. Most research has focused on water quality and aquatic toxicology. Virtually no research has been done on the effects of toxic substance on tropical wildlife. They present a protocol for tropical ecotoxicology that addresses the special problems associated with doing ecotoxicological research in the tropics. The authors discuss the issue of adapting temperate zone principles and methods to tropical environments. Finally, they discuss priority areas for immediate research. These include large scale agricultural activities, especially bananas, pineapples, and soybeans and gold mining with the associated heavy use of mercury. The authors also present a prioritization of tropical wildlife that appear to be at highest risk of exposure to toxic substances.

Lacher, T.E. Jr. [Archbold Tropical Research Center, Clemson, SC (United States); [Inst. of Wildlife and Environmental Toxicology, Pendleton, SC (United States); Goldstein, M.I. [Inst. of Wildlife and Environmental Toxicology, Pendleton, SC (United States)

1995-12-31

146

Tropical Ocean Atmosphere Project  

NSDL National Science Digital Library

The Tropical Atmosphere Ocean array (now called the TAO/TRITON array) consists of approximately 70 moorings in the Tropical Pacific Ocean that transmit oceanographic and meteorological data in real-time via the Argos satellite system. The array is a major component of the El NiÃo/Southern Oscillation Observing System, the Global Climate Observing System and the Global Ocean Observing System. This site features datasets in the form of buoy summary plots, time series plots, section plots, latitude/longitude plots, as well as modeled animations. Real-time and archived data are also searchable by region, array and parameters such as sea surface temperature, salinity, wind, currents and many others. In addition, the site provides an extensive section devoted the El Nino/La Nina phenomenon.

Pacific Marine Environmental Lab

147

Student Research, Tropical Style!  

NSDL National Science Digital Library

A field trip to a tropical location is used to help students examine the process of scientific research. Each student designs a research project, compiles background material, develops the procedure, and builds, buys, or acquires the necessary equipment. A field study trip to a tropical location allows them to collect their data, while demonstrating that science can be interesting and fun! Conclusions are drawn and the final paper is drafted and submitted several weeks after their return. The main area of concentration is marine ecology, but usually each year an additional research topic is offered depending on the location of the field study. One semester of elective high school science credit is awarded for each year. College credit is also offered.

Monte Morris (Clark County R-1 High School REV)

1995-06-30

148

Raintree: Tropical Plant Database  

NSDL National Science Digital Library

Hosted by Raintree, the Tropical Plant Database is authored and maintained by Board Certified Naturopath, Ms. Leslie Taylor to provide accurate information about rainforest plants and to help promote rainforest conservation. Including over 300 pages of documentation on rainforest plants and very well-organized, the Tropical Plant Database lists plants by Common name, Botanical name, Ethnic uses, and Action/disorder. The Database File for each plant includes an illustration and information about family, genus, species, common names, plant description, and more. Visitors can link to great illustrations and photos as well as web resources for each plant including Medline Abstracts, W3 TROPICOS Database, Ethnobotany Database, and Phtyochem Database among others. Plant Database File pages include references as well.

149

Chronic diarrhea in tropics.  

PubMed

Diarrheal diseases continue to be very frequent in the tropics. Upto 40% of mortality associated with diarrheal diseases is associated with prolonged episodes of diarrhea and accompanying malnutrition. Prolonged diarrheal episodes can basically be divided into three main types: a) acute onset prolonged diarrhea or persistent diarrhea; b) insidious onset chronic diarrhea and c) recurrent diarrhea. Epidemiology, risk factors, etiological factors, gut pathophysiology and management of persistent diarrhea has been extensively reviewed in the article. Chronic diarrhea in tropics has entirely different etiological considerations than those observed in Western countries. Most of these factors are associated with poor sanitary and living conditions and gastrointestinal infections. Celiac disease is also identified as an important cause of chronic diarrhea in Indian settings. Chronic diarrhea needs to be differentiated from chronic non specific diarrhea wherein no adverse nutritional effects are seen in the patient. PMID:11132468

Mittal, S K

1999-01-01

150

Tropical Cyclone Eye Thermodynamics  

Microsoft Academic Search

In intense tropical cyclones, sea level pressures at the center are 50-100 hPa lower than outside the vortex, but only 10-30 hPa of the total pressure fall occurs inside the eye between the eyewall and the center. Warming by dry subsidence accounts for this fraction of the total hydrostatic pressure fall. Convection in the eyewall causes the warming by doing

H. E. Willoughby

1998-01-01

151

Hypergravity Effects on Rodent Pregnancy and Parturition  

NASA Technical Reports Server (NTRS)

No mammal has yet undergone birth, or parturition, in the microgravity of space. Previous studies (Ronco & Alberts, 2000) have shown that mid-pregnant rat dams exposed to spaceflight (0-g) and landed 48-72 hrs before term successfully delivered robust, healthy offspring Microgravity-exposed dams exhibited twice the expected numbers of labor contractions whereas length of pregnancy, duration of labor, fetal wastage, number of neonates born and litter gender ratios were identical to controls. In the present study, we report the results of rodent pregnancy and parturition at the opposite end of the gravity spectrum, in hypergravity. Dams exposed to either: 1.0-g, 1.5-g, 1.75-g or 2.0-g from Gestational day (G) 11 and throughout the births of their litters had comparable pregnancy and labor durations, fetal wastage, numbers of neonates born and litter Tender ratios. During parturition, hypergravity-exposed dams exhibited significantly fewer labor contractions as compared to 1.0-g controls. Dams that underwent birth in hypergravity had significantly fewer offspring surviving the immediate postpartum period (P1: 1.0-g, 11.92 +/- 2.84; 1.5-g, 10.88 +/- 2.17; 1.75-g, 9.22 +/-1.99; 2.0-g, 8.83 +/- 3.31). Within 24 hrs postpartum, neonatal survival was further diminished in hypergravity [P2: 100% (1.0-g); 96% (1.5-g); 96% (1.75-g); 73% (2.0-g)] and continued to decline (P10: 100%(1.0-g.); 90%(1.5-g); 87%(1.75-g), 40%(2.0-g)]. Neonatal losses stabilized by P5 for the 1.5-g andl.75-g conditions but continued until P9 for the 2.0-g condition. Together, these findings show that postnatal, but not prenatal, survival is compromised following birth in hypergravity, Maternal and neonatal factors that contribute to peri-parturitional vulnerability to altered gravity environments will be discussed.

Ronca, A. E.; Baer, L. A.; Mills, N. A.; Wade, C. E.; Dalton, Bonnie (Technical Monitor)

2002-01-01

152

Tropical Anvil Cirrus Microphysics  

NASA Astrophysics Data System (ADS)

This study synthesizes data collected during a number of field campaigns by in-situ aircraft to characterize the microphysical properties of tropical, convectively-generated cirrus. The field campaigns include the Tropical Rain Measuring Mission KWAJEX campaign near Kwajalein, M. I., KAMP (the Keys Area Microphysics Project) and the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE), both over southern Florida, and CAMEX-4 (the fourth convection and moisture experiment), studying hurricanes off the east coast of Florida. The measurements include particle size distribution and particle shape information, direct measurements of the condensed water content (CRYSTAL-FACE), and radar imagery. We examine the temperature dependence and vertical variability of the ice water content (IWC), extinction, and effective radii, and deduce the ensemble-mean ice particle densities. Data obtained in quiescent regions outside of convection are compared to observations within convective cells. The relationship between the properties of the particle size distributions and proximity to convection are examined. The IWCs show a strong temperature dependence and dependence on distance below cloud top. The IWCs are larger in the convective regions than in the quiescent regions, and the particle size distributions are markedly broader. Ensemble-mean ice particle densities are a strong function of the breadth of the particle size distributions.

Heymsfield, A.; Bansemer, A.; Schmitt, C.; Baumgardner, D.; Poellot, M.; Twohy, C.; Weinstock, E. M.; Smith, J. T.; Sayres, D.; Avallone, L.; Hallar, G.

2003-12-01

153

Unexpected primitive rodents in the Quaternary of Argentina  

NASA Astrophysics Data System (ADS)

This article describes the first fossils recorded in the Hernandarias Formation (Pleistocene) in Entre Ríos province (eastern Argentina). They are represented by three teeth assigned to the caviomorph rodents (Rodentia, Mammalia) Aenigmys diamantensis gen. et sp. nov. and Eumysops. To establish the phylogenetic affinities of the two most enigmatic teeth, their enamel microstructure was studied. Aenigmys diamantensis is considered the most primitive taxon of a clade formed by Dinomyidae-Neoepiblemidae-Heptaxodontidae. Evidence of the close relationships among these families also is presented herein. The new fossils reinforce previous hypotheses about the survival of primitive Brazilian taxa after their extinction in the Pampas and Patagonia of southern South America. They also show that the diversity of caviomorph rodents during the Quaternary was greater than supposed and that an important Quaternary extinction, not previously detected, affected several lineages. With the available evidence, it is not possible to determine if these rodents indicate a warm pulse or a particular biogeographic situation in Entre Ríos.

Vucetich, María G.; Vieytes, Emma C.; Verzi, Diego H.; Noriega, Jorge I.; Tonni, Eduardo P.

2005-10-01

154

Rodent models for HIV-associated neurocognitive disorders.  

PubMed

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) reflect the spectrum of neural impairments seen during chronic viral infection. Current research efforts focus on improving antiretroviral and adjunctive therapies, defining disease onset and progression, facilitating drug delivery, and halting neurodegeneration and viral resistance. Because HIV is species-specific, generating disease in small-animal models has proved challenging. After two decades of research, rodent HAND models now include those containing a human immune system. Antiviral responses, neuroinflammation and immunocyte blood-brain barrier (BBB) trafficking follow HIV infection in these rodent models. We review these and other rodent models of HAND and discuss their unmet potential in reflecting human pathobiology and in facilitating disease monitoring and therapeutic discoveries. PMID:22305769

Gorantla, Santhi; Poluektova, Larisa; Gendelman, Howard E

2012-03-01

155

Can shrub cover increase predation risk for a desert rodent?  

USGS Publications Warehouse

Previous research indicates that predation risk may influence activity patterns, habitat partitioning, and community structure of nocturnal desert rodents. Shrub microhabitat is typically considered safer than open microhabitat for these small mammals. We investigated predation risk for Townsend's ground squirrels (Spermophilus townsendii), which are diurnal desert rodents that detect predators visually and use burrows for refuge. Our results suggested that shrub cover may increase risk for these squirrels by decreasing their ability to escape from predators. Our field experiment indicated that running speeds of juvenile squirrels were lower in shrub (Ceratoides lanata) habitat than in open areas. Shrub cover was also associated with shorter predator-detection distances (mammalian and avian) and fewer refuges (burrow entrances per hectare) than in open areas in one year but not in another. Our study demonstrated that the visual and locomotive obstruction of vegetative cover may increase predation risk for diurnal desert rodents and that elements of habitat-dependent risk may be temporally dynamic.

Schooley, R.L.; Sharpe, Peter B.

1996-01-01

156

Rodents for comparative aging studies: from mice to beavers.  

PubMed

After humans, mice are the best-studied mammalian species in terms of their biology and genetics. Gerontological research has used mice and rats extensively to generate short- and long-lived mutants, study caloric restriction and more. Mice and rats are valuable model organisms thanks to their small size, short lifespans and fast reproduction. However, when the goal is to further extend the already long human lifespan, studying fast aging species may not provide all the answers. Remarkably, in addition to the fast-aging species, the order Rodentia contains multiple long-lived species with lifespans exceeding 20 years (naked mole-rat, beavers, porcupines, and some squirrels). This diversity opens great opportunities for comparative aging studies. Here we discuss the evolution of lifespan in rodents, review the biology of slow-aging rodents, and show an example of how the use of a comparative approach revealed that telomerase activity coevolved with body mass in rodents. PMID:19424861

Gorbunova, Vera; Bozzella, Michael J; Seluanov, Andrei

2008-09-01

157

Rodents for comparative aging studies: from mice to beavers  

PubMed Central

After humans, mice are the best-studied mammalian species in terms of their biology and genetics. Gerontological research has used mice and rats extensively to generate short- and long-lived mutants, study caloric restriction and more. Mice and rats are valuable model organisms thanks to their small size, short lifespans and fast reproduction. However, when the goal is to further extend the already long human lifespan, studying fast aging species may not provide all the answers. Remarkably, in addition to the fast-aging species, the order Rodentia contains multiple long-lived species with lifespans exceeding 20 years (naked mole-rat, beavers, porcupines, and some squirrels). This diversity opens great opportunities for comparative aging studies. Here we discuss the evolution of lifespan in rodents, review the biology of slow-aging rodents, and show an example of how the use of a comparative approach revealed that telomerase activity coevolved with body mass in rodents. PMID:19424861

Bozzella, Michael J.; Seluanov, Andrei

2008-01-01

158

Anatomy and Histology of Rodent and Human Major Salivary Glands  

PubMed Central

Major salivary glands of both humans and rodents consist of three pairs of macroscopic glands: parotid, submandibular, and sublingual. These glands secrete serous, mucous or mixed saliva via the proper main excretory ducts connecting the glandular bodies with the oral cavity. A series of discoveries about the salivary ducts in the 17th century by Niels Stensen (1638–1686), Thomas Wharton (1614–1673), and Caspar Bartholin (1655–1738) established the concept of exocrine secretion as well as salivary glands. Recent investigations have revealed the endocrine functions of parotin and a variety of cell growth factors produced by salivary glands. The present review aims to describe macroscopic findings on the major salivary glands of rodents and the microscopic differences between those of humans and rodents, which review should be of interest to those researchers studying salivary glands. PMID:23209333

Amano, Osamu; Mizobe, Kenichi; Bando, Yasuhiko; Sakiyama, Koji

2012-01-01

159

Fire in tropical pine ecosystems  

Microsoft Academic Search

\\u000a The genus Pinus extends into tropical environments in the neotropics of Mesoamerica, the Caribbean islands, and the southern tip of the Florida\\u000a peninsula. In Old World tropics, pines occur from southeast China to the Philippines and Southeast Asia. Only one species,\\u000a Pinus merkusii De Vries in Sumatra, occurs south of the equator. Pines in the tropics, as elsewhere, are associated

Ronald L. Myers; Dante Arturo Rodríguez-Trejo

160

Aerobic and anaerobic metabolism during activity in small rodents.  

PubMed

Analysis of oxygen consumption and lactic acid formation during five minutes of maximal activity by the rodents Microtus montanus (Cricetidae) and Dipodomys merriami (Hetermyidae) indicates that: (1) anaerobiosis provides approximately 10% of total energy utilized during the 5-minute activity period; (2) anaerobiosis may account for as much as one-third of total energy utilized during the first 30 seconds of activity. In addition, these data indicate at least one species of lizard may be capable of a higher total rate of metabolism during "burst" activity than are the rodents investigated here. PMID:381568

Ruben, J A; Battalia, D E

1979-04-01

161

Rodent community landscape ecology in grassland-shrubland ecotones and gradients in the Chihuahuan Desert  

Technology Transfer Automated Retrieval System (TEKTRAN)

It is believed that the abundance and diversity of Chihuahuan Desert rodents increases with shrub encroachment accompanying desertification although grassland specialist species decline with loss of perennial grasses. It has been reported, however, that rodent population responses to spatial variati...

162

Fairchild Tropical Botanic Garden 74 FAIRCHILD TROPICAL BOTANIC GARDEN  

E-print Network

Fairchild Tropical Botanic Garden 74 FIU FTBG FAIRCHILD TROPICAL BOTANIC GARDEN This garden, established by Colonel Robert Montgomery in 1938, is one of the fine botanical gardens in North America and a landmark in south Florida. Montgomery estab- lished this garden in commemoration of Dr. David Fairchild

Koptur, Suzanne

163

European Cloth and “Tropical” Skin:  

PubMed Central

As Britain’s imperial and colonial ambitions intensified toward the end of the nineteenth century, the preservation of white European health in tropical climates became an increasingly important concern. Since at least the seventeenth century, the “tropics” had been seen as spaces holding vast potential wealth but also death and disease. To combat these deadly but desirable landscapes, the British built a considerable commodity culture around the preservation of white European health, and for many, tropical clothing was one of the most important and essential items in their “kits.” This article investigates the composition and use of such clothing in relation to British ideas of health and hygiene in tropical climates. First, it considers debates that ensued over the best material—wool, cotton, linen, silk, or a combination of these materials—and the role of “black” skin and local practice in the development of tropical clothing. Second, it demonstrates the importance of location in any discussion of tropical medicine and hygiene, and the tension and ambiguity that still surrounded British ideas of health and hygiene in the tropical colonies. Third, it argues that tropical clothing was important in the maintenance of climatic etiologies despite advances in parasitology and sanitary science. Finally, it considers the relationship of tropical clothing to the formation of a unique colonial identity. To British men and women embarking for any number of tropical destinations, proper clothing was not a banal and mundane component of their outfitting. For many, the clothing signified a departure from the safe and “civil” climes of Britain for adventure in the expanding tropical empire. PMID:19801795

Johnson, Ryan

2009-01-01

164

Seven Guideposts for Tropical Rain Forest Education.  

ERIC Educational Resources Information Center

Identifies seven guideposts for tropical rain forest education. Aids teachers in finding structure and creating educational experiences that promote more complete understanding of tropical rain forests. (CCM)

Rillero, Peter

1999-01-01

165

Atlantic tropical cyclones revisited  

NASA Astrophysics Data System (ADS)

Vigorous discussions have taken place recently in Eos [e.g., Mann and Emanuel, 2006; Landsea, 2007] and elsewhere [Emanuel, 2005; Webster et al., 2005; Hoyos et al., 2006; Trenberth and Shea, 2006; Kossin et al., 2007] regarding trends in North Atlantic tropical cyclone (TC) activity and their potential connection with anthropogenic climate change. In one study, for example [Landsea, 2007], it is argued that a substantial underestimate of Atlantic tropical cyclone counts in earlier decades arising from insufficient observing systems invalidates the conclusion that trends in TC behavior may be connected to climate change. Here we argue that such connections are in fact robust with respect to uncertainties in earlier observations.Several recent studies have investigated trends in various measures of TC activity. Emanuel [2005] showed that a measure of total power dissipation by TCs (the power dissipation index, or PDI) is highly correlated with August-October sea surface temperatures (SST) over the main development region (MDR) for Atlantic TCs over at least the past half century. Some support for this conclusion was provided by Sriver and Ruber [2006]. Webster et al. [2005] demonstrated a statistically significant increase in recent decades in both the total number of the strongest category cyclones (categories 4 and 5) and the proportion of storms reaching hurricane intensity. Hoyos et al. [2006] showed that these increases were closely tied to warming trends in tropical Atlantic SST, while, for example, the modest decrease in vertical wind shear played a more secondary role. Kossin et al. [2007] called into question some trends in other basins, based on a reanalysis of past TC data, but they found the North Atlantic trends to be robust.

Mann, Michael E.; Emanuel, Kerry A.; Holland, Greg J.; Webster, Peter J.

166

Tropical Cyclone Intensity Analysis  

NSDL National Science Digital Library

This lesson provides guidance for operational forecasters needing to combine different intensity methods to determine the intensity of a tropical cyclone. Each of the intensity methods is summarized, focusing on both strengths and weaknesses. These methods include the Dvorak technique, surface observations, scatterometry, the Advanced Dvorak Technique (ADT), microwave sounders (AMSU), SATCON, and subjective interpretation of passive microwave patterns. Consideration of the previous intensity estimate and forecast is also examined. Three case studies task the learner with combining the various methods to derive appropriate intensity estimates and a final quiz tests learner knowledge to demonstrate successful completion of the lesson.

2014-09-14

167

Tropical Fish Rescue  

NSDL National Science Digital Library

Millions of fish eggs from the Caribbean get stuck in the gulf stream every year and drift thousands of miles north where they hatch. Unfortunately, when winter comes, the baby fish will die. In this video, Jonathan joins the New England Aquarium Dive Club on a tropical fish rescue in Rhode Island where they catch some of these fish in the fall before water temperatures plummet. The fish go to the New England Aquarium’s exhibits. Please see the accompanying study guide for educational objectives and discussion points.

Jonathan Bird Productions

2010-02-01

168

Desert-Tropicals.com  

NSDL National Science Digital Library

Created by plant enthusiast Philippe Faucon, Desert-Tropicals.com is a well-designed website with information about, and pictures of, over 3,500 plants. Plant lists are organized by scientific and common name, succulents, xeriscape plants, palm trees, herbs, and trees. The plant lists are quite extensive, and each species receives its own description page with a nice close-up photo as well as brief information about family, frost and heat tolerance, sun exposure, origin, propagation, and more. The site also connects to articles, a Bulletin Board, Bookstore, and relevant links.

Faucon, Philippe

169

Tropical Storm near Bermuda  

NASA Technical Reports Server (NTRS)

This unnamed tropical storm near Bermuda (26.5N, 59.5W) was the result of a strong mid-latitude low pressure system that formed over the Gulf Stream near Cape Hatteras. It rapidly developed into a spiral gyre with internal wind speeds of up to 50 knots and whipped up the sea surface with swells of 15 to 20 feet creating dangerous boating conditions. These sub-hurricane storms are frequent occurances in this region during the fall, winter and spring.

1992-01-01

170

HANTAVIRUS(BUNYAVIRIDAE) INFECTIONS IN RODENTS FROM ORANGE AND SAN DIEGO COUNTIES, CALIFORNIA  

Microsoft Academic Search

During a screening program to determine the extent of hantavirus activity in Orange and San Diego Counties, California, serum samples from 2,365 rodents representing nine genera and 15 species were tested for hantavirus antibodies. A reverse transcription-polymerase chain reaction on selected seropositive rodents was used to identify the specific hantavirus. Rodents positive for Sin Nombre virus (SNV) antibodies by Western

STEPHEN G. BENNETT; JAMES P. WEBB; MINOO B. MADON; JAMES E. CHILDS; THOMAS G. KSIAZEK; NORAH TORREZ-MARTINEZ; BRIAN HJELLE

171

Serologic Survey of Oklahoma Rodents: Evidence for the Presence of a Hantavirus and an Arenavirus  

Microsoft Academic Search

We conducted a statewide survey of Oklahoma small mammals to test for antibod- ies against rodent-borne viral diseases. Four rodent species had antibody to Sin Nombre virus (SNV), the primary causative agent of hantavirus pulmonary syn- drome (HPS), and two species had antibody to Whitewater Arroyo virus, an arenavirus associated with human fatalities. The rodent reservoirs for other HPS- causing

Richard A. Nisbett; Michael D. Stuart; Gloria M. Caddell; Charles H. Calisher

2001-01-01

172

Rodent foraging is affected by indirect, but not by direct, cues of predation risk  

E-print Network

Rodent foraging is affected by indirect, but not by direct, cues of predation risk John L. Orrock, Odocoileus virginianus), or a water control. Rather, GUD was related to microhabitat: rodents removed more of cover. Rodents also removed more seeds during nights with precipitation and when moon illumination

Orrock, John

173

Structurally complex habitat and sensory adaptations mediate the behavioural responses of a desert rodent  

E-print Network

rodent to an indirect cue for increased predation risk Yael Mandelik,* Menna Jones and Tamar Dayan of a rocky desert rodent, the common spiny mouse (Acomys cahirinus), to gain insight into how structural with results for sandy desert rodents. The structurally complex habitat of the rocky desert environment enabled

Dayan, Tamar

174

Evidence for Higher Rates of Nucleotide Substitution in Rodents Than in Man  

Microsoft Academic Search

When the coding regions of 11 genes from rodents (mouse or rat) and man are compared with those from another mammalian species (usually bovine), it is found that rodents evolve significantly faster than man. The ratio of the number of nucleotide substitutions in the rodent lineage to that in the human lineage since their divergence is 2.0 for synonymous substitutions

Chung-I. Wu; Wen-Hsiung Li

1985-01-01

175

The Touchscreen Cognitive Testing Method for Rodents: How to Get the Best out of Your Rat  

ERIC Educational Resources Information Center

The touchscreen testing method for rodents is a computer-automated behavioral testing method that allows computer graphic stimuli to be presented to rodents and the rodents to respond to the computer screen via a nose-poke directly to the stimulus. The advantages of this method are numerous; however, a systematic study of the parameters that…

Bussey, Timothy J.; Padain, Tina L.; Skillings, Elizabeth A.; Winters, Boyer D.; Morton, A. Jennifer; Saksida, Lisa M.

2008-01-01

176

Tropical Rainforest Education. ERIC Digest.  

ERIC Educational Resources Information Center

This digest provides four guideposts for tropical rainforest education: (1) structure; (2) location and climate; (3) importance; and (4) conservation of resources. Research is cited and background information provided about the layers of life and the adaptations of life within the tropical rain forest. Aspects of life within and near rain forests…

Rillero, Peter

177

Agricultural droughts in the tropics  

Microsoft Academic Search

Irregular droughts are the main reason for serious yield reductions in tropical agriculture, with sometimes very serious consequences. These “agricultural droughts” are defined and delimited in relation to normal rainfall conditions, to which traditional agricultural production systems are fully adapted. Examples from East Africa and Malaysia, tropical areas which differ climatically and in the availability of climatic data, illustrate that

S. Nieuwolt

1986-01-01

178

Climate and the Tropical Oceans  

Microsoft Academic Search

An attempt is made to determine the role of the ocean in establishing the mean tropical climate and its sensitivity to radiative perturbations. A simple two-box energy balance model is developed that includes ocean heat transports as an interactive component of the tropical climate system. It is found that changes in the zonal mean ocean heat transport can have a

Amy Clement; Richard Seager

1999-01-01

179

Hurricanes and Tropical Meteorology Background  

E-print Network

- 1 - Hurricanes and Tropical Meteorology Background: Over the last 20 years, hurricane research at AOML has focused on improved scientific understanding of hurricanes and of tropical meteorology scientific goals for AOMLs hurricane research derive from the U.S. Weather Research Programs (USWRP

180

Combating tropical deforestation in Haiti  

SciTech Connect

This article outlines the findings of Tropical Forestry Action Plan (TFAP), which was part of an international initiative on tropical deforestation. Ten specific recommendations are addressed. Haiti has lost more than 97% of its forestland, so emphasis should be placed on replenishing the forest cover.

Pellek, R.

1990-09-01

181

Managing the Tropical Agriculture Revolution  

Microsoft Academic Search

Industrial production of beef, soybeans, cotton, and biofuels is expanding into the tropical latitudes of South America and may soon reach tropical Africa in the most important agricultural transition since the Green Revolution. This shift is driven by the shortage of land suitable for expansion of cultivation and grazing in the temperate zone, increased global demands for agricultural commodities, the

Daniel C. Nepstad; Claudia M. Stickler

2008-01-01

182

POVERTY REDUCTION BY TROPICAL FORESTS?  

Microsoft Academic Search

Human Development Index as a national poverty measure is regressed with relative forest area as a dependent variable, and with population density, and six other independent variables in 64 tropical countries. They cover 84 % of the total tropical forest area. It was found that the adopted poverty variable was strongly correlated with the relative forest area. It was assumed

Matti Palo; Erkki Lehto

183

Tropical Cyclone Report Hurricane Karen  

E-print Network

of the Cape Verde Islands. The system moved west-northwestward with little change in organization until late of a tropical depression centered about 720 n mi west-southwest of the Cape Verde Islands at 0000 UTC 25Tropical Cyclone Report Hurricane Karen (AL122007) 25-29 September 2007 Richard J. Pasch National

184

DESERT RODENTS REDUCE SEEDLING RECRUITMENT OF SALSOLA PAULSENII  

Technology Transfer Automated Retrieval System (TEKTRAN)

Heteromyid rodents in the deserts of North America have been shown to harvest large quantities of seeds of both native and introduced plants from soil seedbanks, but rarely has the impact of this seed removal been demonstrated experimentally. I used a series of fenced plots (some of which excluded ...

185

Recent and Widespread Rapid Morphological Change in Rodents  

PubMed Central

In general, rapid morphological change in mammals has been infrequently documented. Examples that do exist are almost exclusively of rodents on islands. Such changes are usually attributed to selective release or founder events related to restricted gene flow in island settings. Here we document rapid morphological changes in rodents in 20 of 28 museum series collected on four continents, including 15 of 23 mainland sites. Approximately 17,000 measurements were taken of 1302 rodents. Trends included both increases and decreases in the 15 morphological traits measured, but slightly more trends were towards larger size. Generalized linear models indicated that changes in several of the individual morphological traits were associated with changes in human population density, current temperature gradients, and/or trends in temperature and precipitation. When we restricted these analyses to samples taken in the US (where data on human population trends were presumed to be more accurate), we found changes in two additional traits to be positively correlated with changes in human population density. Principle component analysis revealed general trends in cranial and external size, but these general trends were uncorrelated with climate or human population density. Our results indicate that over the last 100+ years, rapid morphological change in rodents has occurred quite frequently, and that these changes have taken place on the mainland as well as on islands. Our results also suggest that these changes may be driven, at least in part, by human population growth and climate change. PMID:19649284

Pergams, Oliver R. W.; Lawler, Joshua J.

2009-01-01

186

Arenavirus antibody in rodents indigenous to coastal southern California.  

PubMed

The purpose of this study was to extend our knowledge on the geographic and natural rodent host ranges of New World arenaviruses in California. Sera from 1,094 sigmodontine and 112 murine rodents were tested for antibody against Whitewater Arroyo and Amapari viruses. Antibody was found in 55 (4.6%) of the 1,206 rodents: 4 from northwestern San Diego County, 3 from Los Angeles County, and 48 from Orange County. The antibody-positive rodents included 8 (7.8%) of 103 Neotoma fuscipes, 1 (0.6%) of 180 Neotoma lepida, 1 (3.1%) of 32 Peromyscus boylii, 8 (11.0%) of 73 Peromyscus californicus, 1 (1.2%) of 85 Peromyscus eremicus, 30 (8.5%) of 353 Peromyscus maniculatus, and 6 (2.2%) of 268 Reithrodontomys megalotis. This study provides the first evidence that New World arenaviruses occur in Los Angeles and Orange counties and northwestern San Diego County, and the first evidence that Peromyscus and Reithrodontomys species are naturally infected with New World arenaviruses. PMID:11289675

Bennett, S G; Milazzo, M L; Webb, J P; Fulhorst, C F

2000-05-01

187

Lassa serology in natural populations of rodents and horizontal transmission.  

PubMed

Lassa virus causes hemorrhagic fever in West Africa. Previously, we demonstrated by PCR screening that only the multimammate mouse, Mastomys natalensis, hosts Lassa virus in Guinea. In the present study, we used the same specimen collection from 17 villages in Coastal, Upper, and Forest Guinea to investigate the Lassa virus serology in the rodent population. The aim was to determine the dynamics of antibody development in M. natalensis and to detect potential spillover infections in other rodent species. Immunoglobulin G (IgG) antibody screening was performed using the indirect immunofluorescence assay with the Guinean Lassa virus strain Bantou 289 as antigen. The overall seroprevalence was 8% (129/1551) with the following rodents testing positive: 109 M. natalensis, seven Mastomys erythroleucus, four Lemniscomys striatus, four Praomys daltoni, three Mus minutoides, and two Praomys rostratus. Nearly all of them (122/129) originated from Bantou, Tanganya, and Gbetaya, where Lassa virus is highly endemic in M. natalensis. The antibody seroprevalence in M. natalensis from this high-endemic area (27%; 108/396) depended on the village, habitat, host age, and host abundance. A main positive factor was age; the maximum seroprevalence reached 50% in older animals. Our data fit with a model implicating that most M. natalensis rodents become horizontally infected, clear the virus within a period significantly shorter than their life span, and develop antibodies. In addition, the detection of antibodies in other species trapped in the habitats of M. natalensis suggests spillover infections. PMID:25229705

Fichet-Calvet, Elisabeth; Becker-Ziaja, Beate; Koivogui, Lamine; Günther, Stephan

2014-09-01

188

Rodents as seed dispersers in a heath — oak wood succession  

Microsoft Academic Search

In a Danish heathland invasion of oak shrub has taken place, the succession rate being approximately 300 m during the last 100 years. The colonisation has occurred in steps related to the delay time between seedling stage and fertility stage. Seedlings are often found in clusters originating from caches probably made by seed-eating rodents. Apodemus sylvaticus, A. flavicollis and Clethrionomys

Thomas Secher Jensen; Ole Frost Nielsen

1986-01-01

189

COMPLEMENTARITY OF GENOTOXIC AND NONGENOTOXIC PREDICTORS OF RODENT CARCINOGENICITY  

EPA Science Inventory

Twenty-one chemicals known to be carcinogenic in rodent bioassays were selected for study. he chemicals were administered by gavage in two dose levels to female Sprague-Dawley rats. he effects of these 21 chemicals on four biochemical assays (hepatic DNA damage by alkaline elutio...

190

Evolution of the Genomic Recombination Rate in Murid Rodents  

PubMed Central

Although very closely related species can differ in their fine-scale patterns of recombination hotspots, variation in the average genomic recombination rate among recently diverged taxa has rarely been surveyed. We measured recombination rates in eight species that collectively represent several temporal scales of divergence within a single rodent family, Muridae. We used a cytological approach that enables in situ visualization of crossovers at meiosis to quantify recombination rates in multiple males from each rodent group. We uncovered large differences in genomic recombination rate between rodent species, which were independent of karyotypic variation. The divergence in genomic recombination rate that we document is not proportional to DNA sequence divergence, suggesting that recombination has evolved at variable rates along the murid phylogeny. Additionally, we document significant variation in genomic recombination rate both within and between subspecies of house mice. Recombination rates estimated in F1 hybrids reveal evidence for sex-linked loci contributing to the evolution of recombination in house mice. Our results provide one of the first detailed portraits of genomic-scale recombination rate variation within a single mammalian family and demonstrate that the low recombination rates in laboratory mice and rats reflect a more general reduction in recombination rate across murid rodents. PMID:21149647

Dumont, Beth L.; Payseur, Bret A.

2011-01-01

191

Virulence, drug sensitivity and transmission success in the rodent malaria,  

E-print Network

Here, we test the hypothesis that virulent malaria parasites are less susceptible to drug treatmentVirulence, drug sensitivity and transmission success in the rodent malaria, Plasmodium chabaudi than less virulent parasites. If true, drug treatment might promote the evolution of more virulent

Read, Andrew

192

Temporal changes in a Chihuahuan Desert rodent community  

Microsoft Academic Search

We used time series analysis of ten years of monthly census data to assess the responses of both individual species and an entire community of rodents to a fluctu- ating desert environment. Autocorrelation analysis revealed different patterns of intra-annual fluctuation among the It species: Dipodomys spectabilis and Perog- nathus Jarus had pronounced annual cycles: D. ordii, D. merriaini, Chaetodipus penicillutu~,

James H. Brown; Edward J. Heske

1990-01-01

193

A mechanism for resource allocation among sympatric heteromyid rodent species  

Microsoft Academic Search

Laboratory feeding experiments were conducted with Dipodomys ordii and Perognathus flavus in an attempt to discover a mechanism which might result in seed size selection. There was no marked difference in the proportions of four seed types collected whether the rodents foraged in the presence or absence of one another. However, analysis of the variability in weight of each of

Richard L. Hutto

1978-01-01

194

PERFLUOROOCTANE SULFONATE (PFOS) DISRUPTS THE THYROID STATUS IN LABORATORY RODENTS  

EPA Science Inventory

PERFLUOROOCTANE SULFONATE (PFOS) DISRUPTS THE THYROID STATUS IN LABORATORY RODENTS. C. Lau, J.R. Thibodeaux, R.G. Hanson, B.E. Gray and J.M. Rogers. Reprod. Tox. Div. NHEERL, US EPA, Research Triangle Park, NC. PFOS is an environmental contaminant ubiquitously found in h...

195

Ultrasonic attenuation imaging in a rodent thyroid cancer model  

E-print Network

has personal and societal consequences (e.g., the need of lifelong thyroid hormone replacementUltrasonic attenuation imaging in a rodent thyroid cancer model Omar Zenteno¹, William Ridgway-Champaign, Urbana, IL 61801, USA. Abstract--The incidence of diagnosed thyroid cancer has increased significantly

Illinois at Urbana-Champaign, University of

196

Evaluation of two oral baiting systems for wild rodents.  

PubMed

Tetracycline hydrochloride (TC)-treated peanut butter or rodent chow baits were distributed during March 1990, on separate 0.53 ha sites in Oglethorpe County, Georgia (USA). Rodents were trapped on a control site prior to bait distribution and on two baited sites 6 days post-distribution. Cleaned skulls from euthanized mammals were grossly examined for TC fluorescence using an ultraviolet (UV) light. Mandibles were sectioned and examined for TC fluorescence using an ultraviolet light microscope. All 21 cotton rats (Sigmodon hispidus), four eastern harvest mice (Rithrodontomys humulis), and two golden mice (Ochrotomys nuttalli) captured on the control site were negative for TC fluorescence. On the peanut butter bait site, mandible sections from 29 of 32 (91%) cotton rats, three of three (100%) eastern harvest mice, two of three (66%) golden mice, zero of five (0%) white-footed mice (Peromyscus leucopus), one of three (33%) short-tailed shrews (Blarina brevicauda), and zero of two (0%) least shrews (Cryptotis parva) were positive for TC. Results from the rodent chow bait site indicated that 18 of 25 (72%) cotton rats, zero of three (0%) eastern harvest mice, two of seven (29%) golden mice, zero of four (0%) white-footed mice, and zero of four (0%) least shrews were positive for TC fluorescence in mandible sections. These results suggest that a large portion of a free-ranging small rodent population can be administered biological markers or vaccines using baits. PMID:9577787

Creekmore, T E; Fletcher, W O; Stallknecht, D E

1998-04-01

197

Leptospira spp. in Rodents and Shrews in Germany  

PubMed Central

Leptospirosis is an acute, febrile disease occurring in humans and animals worldwide. Leptospira spp. are usually transmitted through direct or indirect contact with the urine of infected reservoir animals. Among wildlife species, rodents act as the most important reservoir for both human and animal infection. To gain a better understanding of the occurrence and distribution of pathogenic leptospires in rodent and shrew populations in Germany, kidney specimens of 2973 animals from 11 of the 16 federal states were examined by PCR. Rodent species captured included five murine species (family Muridae), six vole species (family Cricetidae) and six shrew species (family Soricidae). The most abundantly trapped animals were representatives of the rodent species Apodemus flavicollis, Clethrionomys glareolus and Microtus agrestis. Leptospiral DNA was amplified in 10% of all animals originating from eight of the 11 federal states. The highest carrier rate was found in Microtus spp. (13%), followed by Apodemus spp. (11%) and Clethrionomys spp. (6%). The most common Leptospira genomospecies determined by duplex PCR was L. kirschneri, followed by L. interrogans and L. borgpetersenii; all identified by single locus sequence typing (SLST). Representatives of the shrew species were also carriers of Leptospira spp. In 20% of Crocidura spp. and 6% of the Sorex spp. leptospiral DNA was detected. Here, only the pathogenic genomospecies L. kirschneri was identified. PMID:25062275

Mayer-Scholl, Anne; Hammerl, Jens Andre; Schmidt, Sabrina; Ulrich, Rainer G.; Pfeffer, Martin; Woll, Dietlinde; Scholz, Holger C.; Thomas, Astrid; Nöckler, Karsten

2014-01-01

198

CONCENTRATED AMBIENT PARTICULATE STUDIES IN HEALTHY AND COMPROMISED RODENTS  

EPA Science Inventory

CONCENTRATED AMBIENT PARTICULATE STUDIES IN HEALTHY AND COMPROMISED RODENTS. WP Watkinson1, LB Wichers2, JP Nolan1, DW Winsett1, UP Kodavanti1, MCJ Schladweiler1, LC Walsh1, ER Lappi1, D Terrell1, R Slade1, AD Ledbetter1, and DL Costa1. 1USEPA, ORD/NHEERL/ETD/PTB, RTP, NC, US...

199

Lagomorph and rodent responses to two protein hydrolysates  

Microsoft Academic Search

Various species of rodents and lagomorphs were used in bioassays to determine the effectiveness of protein hydrolysates (specifically hydrolyzed casein and gelatin) as herbivore repellents. Mixed sex groups of captive rabbits, pocket gophers, voles, and mountain beavers were offered hydrolyzed casein or gelatin test diets in single-choice tests following a training period with a hydrolysate-free diet. The effectiveness of either

Julia A. Figueroa; Bruce A. Kimball; Kelly R. Perry

2008-01-01

200

Tropical Synoptic Meteorology Curriculum Package  

NSDL National Science Digital Library

The Tropical Synoptic Meteorology Curriculum Package is a university-level, online meteorology course package. It is freely available to interested institutions that are expanding their course offerings, particularly their online offerings. The course fulfills the synoptic and mesoscale meteorology requirements for the World Meteorological Organization (WMO) Basic Instruction Package for Meteorology (BIP-M), but with an emphasis on the tropics to provide focus for those working or planning to work in tropical regions. The course utilizes existing and newly developed resources, including the online textbook, Introduction to Tropical Meteorology (http://www.meted.ucar.edu/tropical/textbook_2nd_edition/). The course package includes an instructor’s guide and model syllabus with learning objectives, free online instructional resources, introductory slides for faculty use, case examples, questions for review or discussion, student assignments, quizzes, learning activities, and guidance for online course delivery. All materials are made available in Google Docs format for downloading and customizing.

2014-09-14

201

The energetics of a Malagasy rodent, Macrotarsomys ingens (Nesomyinae): a test of island and zoogeographical effects on metabolism.  

PubMed

This study provides first insights into the energetics of the Nesomyinae, a subfamily of rodents endemic to Madagascar. The ancestral nesomyine colonized Madagascar from Africa ca. 30-15 mya at the onset of Oligocene global cooling. We tested the hypothesis that, contrary to what might be expected from Island Biogeography theory, post-colonization character displacement of thermoregulatory traits was constrained by phylogenetic inertia through climate adaptation. The study was conducted in the Parc National d'Ankarafantsika, Madagascar. We measured the basal metabolic rate (BMR) and body temperature (T b) patterns of naturally warm-acclimated, freshly captured adult long-tailed big-footed mice Macrotarsomys ingens (67.4 g). The mean ± SD BMR of M. ingens was 0.298 ± 0.032 Watts (n = 12), 31.7 % lower than that predicted by a phylogenetically independent allometric equation. Body mass was correlated with BMR. The lower critical limit of thermoneutrality (T lc) was 30.7°C. The mean ± SD T b = 36.1 ± 0.8°C (n = 12) compared well with the mean T b values for myomorph rodents from the Afrotropical zone, but was lower than those of the Neotropical and Palearctic zones. M. ingens became pathologically hypothermic when exposed to ambient temperatures lower than 18°C. The soil temperature at depths of 250 mm and deeper did not decrease below 22°C throughout the austral winter. The thermoregulatory data for M. ingens did not differ from those that characterize mainland Afrotropical rodents. However, BMR and T b were lower than those of Holarctic rodents. Thus, contrary to expectations of Island Biogeography theory that rapid character displacement often occurs in morphological and behavioural traits when mammals colonize islands, M. ingens displayed climate-related physiological traits indicative of phylogenetic inertia. Presumably the tropical conditions that prevailed on Madagascar at the time of colonisation differed very little from those of the African mainland, and hence there was no strong driving force for change. Unlike small tenrecs and lemurs that radiated on Madagascar prior to the Oligocene, traits associated with an insular existence, such as daily torpor and hibernation, were not evident in M. ingens. PMID:25189668

Lobban, Kerileigh D; Lovegrove, Barry G; Rakotondravony, Daniel

2014-12-01

202

Molecular evolution and phylogenetics of rodent malaria parasites  

PubMed Central

Background Over the last 6 decades, rodent Plasmodium species have become key model systems for understanding the basic biology of malaria parasites. Cell and molecular parasitology have made much progress in identifying genes underpinning interactions between malaria parasites, hosts, and vectors. However, little attention has been paid to the evolutionary genetics of parasites, which provides context for identifying potential therapeutic targets and for understanding the selective forces shaping parasites in natural populations. Additionally, understanding the relationships between species, subspecies, and strains, is necessary to maximize the utility of rodent malaria parasites as medically important infectious disease models, and for investigating the evolution of host-parasite interactions. Results Here, we collected multi-locus sequence data from 58 rodent malaria genotypes distributed throughout 13 subspecies belonging to P. berghei, P. chabaudi, P. vinckei, and P. yoelii. We employ multi-locus methods to infer the subspecies phylogeny, and use population-genetic approaches to elucidate the selective patterns shaping the evolution of these organisms. Our results reveal a time-line for the evolution of rodent Plasmodium and suggest that all the subspecies are independently evolving lineages (i.e. species). We show that estimates of species-level polymorphism are inflated if subspecies are not explicitly recognized, and detect purifying selection at most loci. Conclusions Our work resolves previous inconsistencies in the phylogeny of rodent malaria parasites, provides estimates of important parameters that relate to the parasite’s natural history and provides a much-needed evolutionary context for understanding diverse biological aspects from the cross-reactivity of immune responses to parasite mating patterns. PMID:23151308

2012-01-01

203

Nutritional Evaluation of NASA's Rodent Food Bar Diet  

NASA Technical Reports Server (NTRS)

Tests are being conducted on NASA's rodent Food Bar in preparation for long-term use as the rat and mouse diet aboard the International Space Station. Nutritional analyses are performed after the bars are manufactured and then repeated periodically to determine nutritional stability. The primary factors analyzed are protein, ash, fat, fiber, moisture, amino acids, fatty acids, and minerals. Nutrient levels are compared to values published in the National Research Council's dietary requirements for rodents, and also to those contained in several commonly used commercial rodent lab diets. The Food Bar is manufactured from a powdered diet to which moisture is added as it is processed through an extruder. The bars are dipped into potassium sorbate, vacuum-sealed, and irradiated. In order to determine nutrient changes during extrusion and irradiation, the powdered diet, the non-irradiated bars, and the irradiated bars are all analyzed. We have observed lower values for some nutrients (iodine, vitamin K, and iron) in the Food Bars compared with NRC requirements. Many nutrients in the Food Bars are contained at a higher level than levels in the NRC requirements. An additional factor we are investigating is the 26% moisture level in the Food Bars, which drops to about 15% within a week, compared to a stable 10% moisture in many standard lab chow diets. In addition to the nutritional analyses, the food bar is being fed to several strains of rats and mice, and feeding study and necropsy results are being observed (Barrett et al, unpublished data). Information from the nutritional analyses and from the rodent studies will enable us to recommend the formulation that will most adequately meet the rodent Food Bar requirements for long-term use aboard the Space Station.

Barrett, Joyce E.; Yu, Diane S.; Dalton, Bonnie P.

2000-01-01

204

Tropical chronic pancreatitis  

PubMed Central

Tropical chronic pancreatitis (TCP) is a juvenile form of chronic calcific non-alcoholic pancreatitis, seen almost exclusively in the developing countries of the tropical world. The classical triad of TCP consists of abdominal pain, steatorrhoea, and diabetes. When diabetes is present, the condition is called fibrocalculous pancreatic diabetes (FCPD) which is thus a later stage of TCP. Some of the distinctive features of TCP are younger age at onset, presence of large intraductal calculi, more aggressive course of the disease, and a high susceptibility to pancreatic cancer. Pancreatic calculi are the hallmark for the diagnosis of TCP and in non-calcific cases ductal dilation on endoscopic retrograde cholangiopancreatography, computed tomography, or ultrasound helps to identify the disease. Diabetes is usually quite severe and of the insulin requiring type, but ketosis is rare. Microvascular complications of diabetes occur as frequently as in type 2 diabetes but macrovascular complications are uncommon. Pancreatic enzyme supplements are used for relief of abdominal pain and reducing the symptoms related to steatorrhoea. Early diagnosis and better control of the endocrine and exocrine dysfunction could help to ensure better survival and improve the prognosis and quality of life of TCP patients. PMID:14654569

Barman, K; Premalatha, G; Mohan, V

2003-01-01

205

Smithsonian Tropical Research Institute  

NSDL National Science Digital Library

Most visitors to the Smithsonian Institution's museums in Washington, DC may not be aware of the activities of their Tropical Research Institute, which may have something to do with the fact that is located in Panama. The Institute's history stretches back to the early years of the 20th century, when one of its prime directives was to survey the flora and fauna of the area for the purpose of controlling diseases such as yellow fever and malaria. In 1946, the Institute came into the fold of the Smithsonian Institution, and since then it has conducted research in the areas of archaeology, behavioral ecology, environmental monitoring, and other topics. On the site, visitors can learn about the intitute's diverse research projects, international activities (such as the Center for Tropical Forest Science), and fellowship opportunities. Finally, visitors can also look at the two webcams operated by the Institute, including one that looks over the island (Barro Colorado) where they are located off the coast of Panama.

206

Tropical Cyclone Information System  

NASA Technical Reports Server (NTRS)

The JPL Tropical Cyclone Infor ma tion System (TCIS) is a Web portal (http://tropicalcyclone.jpl.nasa.gov) that provides researchers with an extensive set of observed hurricane parameters together with large-scale and convection resolving model outputs. It provides a comprehensive set of high-resolution satellite (see figure), airborne, and in-situ observations in both image and data formats. Large-scale datasets depict the surrounding environmental parameters such as SST (Sea Surface Temperature) and aerosol loading. Model outputs and analysis tools are provided to evaluate model performance and compare observations from different platforms. The system pertains to the thermodynamic and microphysical structure of the storm, the air-sea interaction processes, and the larger-scale environment as depicted by ocean heat content and the aerosol loading of the environment. Currently, the TCIS is populated with satellite observations of all tropical cyclones observed globally during 2005. There is a plan to extend the database both forward in time till present as well as backward to 1998. The portal is powered by a MySQL database and an Apache/Tomcat Web server on a Linux system. The interactive graphic user interface is provided by Google Map.

Li, P. Peggy; Knosp, Brian W.; Vu, Quoc A.; Yi, Chao; Hristova-Veleva, Svetla M.

2009-01-01

207

TROPICAL FRUIT URBAN FORESTRY AT THE WHITMAN TROPICAL FRUIT PLAZA OF FAIRCHILD TROPICAL BOTANIC GARDEN  

Microsoft Academic Search

South Florida horticulture continues to evolve. Changes are due to urbanization, governmental regulation, foreign competition and the needs of the growing community. An urban forestry project was initiated in 2004 at FTBG in conjunction with the Whitman Tropical Fruit Pavilion. This project provides the home owner and estate gardener with examples of tropical fruit in the urban landscape. The formal

Noris Ledesma; Richard J. Campbell; Juan Valls

208

CHEMICAL AND RADIATION LEUKEMOGENESIS IN HUMANS AND RODENTS AND THE VALUE OF RODENT MODELS FOR ASSESSING RISKS OF LYMPHOHEMATOPOIETIC CANCERS  

EPA Science Inventory

This report is intended to provide an up-to-date overview of the lymphoid and hematopoietic diseases induced in humans and rodents following exposure to chemical agents. It includes a brief introduction to hematopoiesis and leukemia-inducing agents and their effects in mice and r...

209

Tropical Curves and Amoebas Jan Verschelde  

E-print Network

and fans stable intersection 4 Tropical Rain Forest 5 Linear Algebra Jan Verschelde (UIC) Tropical CurvesTropical Curves and Amoebas Jan Verschelde University of Illinois at Chicago Department Computational Algebraic Geometry Seminar Jan Verschelde (UIC) Tropical Curves and Amoebas 23 January 2014 1 / 26

Verschelde, Jan

210

Copyrighted Material What Is Tropical Ecology?  

E-print Network

Copyrighted Material What Is Tropical Ecology? Asking the question, What is tropical ecology? may seem akin to asking questions such as, Who is buried in Grant's tomb? Tropical ecology is the study of the ecology of tropical regions. But so what? Consider these questions: First, what is ecology? What are its

Landweber, Laura

211

The Nitrogen Paradox in Tropical Forest Ecosystems  

E-print Network

cycle, tropical forests, global biogeochemistry, nitrogen fixation, nutrients, phosphorus Abstract Observations of the tropical nitrogen (N) cycle over the past half century indicate that intact tropical in the resolution of the nitrogen (N) cycle across this vast biome. Although tropical forests are quite variable

212

World Health Organization: Tropical Diseases  

NSDL National Science Digital Library

This World Health Organization website feature focuses on tropical diseases. For visitors unfamiliar with which diseases out there are considered tropical, this website provides informative fact sheets on fourteen different tropical diseases. To view the factsheets, visitors should click on "Fact Sheets on Tropical Diseases", under the General Information heading near the top of the homepage. The fact sheets cover topics such as "Symptoms", "Transmission", "Treatment", "Prevention", "Economic Cost", and "Diagnosis". Under the "Multimedia" heading near the top of the homepage, visitors can click on the link "10 Facts on Neglected Tropical Diseases", to be taken to a slide show, via the link near the bottom of the page entitled "Read More About Neglected Tropical Diseases". The slide show explains that a neglected tropical disease is a disease that costs little to prevent, does not spread to wealthy areas and is of little priority to pharmaceutical companies when it comes to research and development of medicines for them. Under the Statistics heading near the bottom of the homepage, visitors can click on a link to get to the "Global Health Database", which contains "standardized data and statistics for infectious diseases at country, regional, and global levels."

213

Tropical Ice Cores Measure Climate  

NSDL National Science Digital Library

This video profiles glaciologist Lonnie Thompson and his research into tropical mountain glaciers as a way to understand climate history. Beginning in the 1970s, Thompson recognized that tropical ice cores contain information relating to tropical climate phenomena, including El NiÃo events and monsoons. These phenomena are not archived in ice from polar regions. Thompson explains that his archive of ice cores is full of clues that, taken together with records collected from around the world, can help scientists create a timeline that tells Earth's climate story.

NOVA scienceNOW

214

A perspective on tropical sprue.  

PubMed

A diagnosis of tropical sprue, an infrequent affliction of inhabitants and travelers in tropical regions, should be considered in patients with a compatible history, malabsorption, and chronic diarrhea. It can occur in either endemic or epidemic form and can be preceded by acute gastroenteritis. The cause of tropical sprue is still unknown, although most data support an infectious etiology. Therapeutic experience is greatest with folic acid and tetracycline. Most patients can be expected to recover with proper nutritional support, although relapses and slow responses occur. PMID:11470001

Lim, M L

2001-08-01

215

Tropical Cyclone Eye Dynamics.  

NASA Astrophysics Data System (ADS)

A new perspective of the dynamics of a tropical cyclone eye is given in which eye subsidence and the adiabatic warming accompanying it are accounted for directly from the equations of motion. Subsidence is driven by an adverse, axial gradient of perturbation pressure which is associated principally with the decay and/or radial spread of the tangential wind field with height at those levels of the cyclone where the tangential winds are approximately in gradient wind balance. However, this pressure gradient is almost exactly opposed by the buoyancy force field due to adiabatic warming. This corroborates with observational data.The relationship between the present view of eye dynamics and those of Malkus and Kuo and a recent study by Willoughby is discussed in detail.

Smith, R. K.

1980-06-01

216

Tropical Cyclone Report  

NSDL National Science Digital Library

This detailed description of Hurricane Isabel, a long-lived Cape Verde hurricane that reached Category 5 status on the Saffir-Simpson Hurricane Scale, contains a synoptic history, meteorological statistics, casualty and damage statistics, and a forecast and warning critique. The storm made landfall near Drum Inlet on the Outer Banks of North Carolina as a category 2 hurricane and is considered to be one of the most significant tropical cyclones to affect portions of northeastern North Carolina and east-central Virginia since Hurricane Hazel in 1954 and the Chesapeake-Potomac Hurricane of 1933. Voluminous charts include best track, selected ship reports, selected surface observations, and rainfall. A warnings chart is also included along with a best track map.

2007-12-12

217

Residential indoor humidity control in tropics and sub-tropics  

Microsoft Academic Search

The use of direct expansion (DX) air conditioning (A\\/C) systems is widely seen in residential buildings in tropics and sub-tropics. However, most DX A\\/C systems are equipped with single-speed compressor and supply fan, relying on On—Off cycling as a low-cost approach to maintain only indoor dry-bulb temperature, whereas the indoor air humidity is not controlled directly. This also leads to

MY Chan; SM Deng; XG Xu

2009-01-01

218

Heteroxenous coccidia increase the predation risk of parasitized rodents.  

PubMed

We have investigated the influence of heteroxenous coccidia (Apicomplexa: Eimeriorina) on the predation risk of intermediate hosts. Voles infected with Frenkelia spp. were found more frequently in buzzards' (Buteo buteo) prey than among snap-trapped rodents. To eliminate the possibility of traps selecting for uninfected rodents, a laboratory experiment was performed. Mice experimentally infected with Sarcocystis dispersa seemed to be more likely caught by the final host, the long-eared owl (Asio otus); this result was confirmed by a mathematical model. Field data confirmed the adaptive value of parasite-induced changes. The increase of predation is directed towards the specific final host only or is non-specific. In the populations studied the probability of predation of parasitized individuals by the specific predator was increased. PMID:9881375

Vorísek, P; Votýpka, J; Zvára, K; Svobodová, M

1998-12-01

219

Pet Rodents and Fatal Lymphocytic Choriomeningitis in Transplant Patients  

PubMed Central

In April 2005, 4 transplant recipients became ill after receiving organs infected with lymphocytic choriomeningitis virus (LCMV); 3 subsequently died. All organs came from a donor who had been exposed to a hamster infected with LCMV. The hamster was traced back through a Rhode Island pet store to a distribution center in Ohio, and more LCMV-infected hamsters were discovered in both. Rodents from the Ohio facility and its parent facility in Arkansas were tested for the same LCMV strain as the 1 involved in the transplant-associated deaths. Phylogenetic analysis of virus sequences linked the rodents from the Ohio facility to the Rhode Island pet store, the index hamster, and the transplant recipients. This report details the animal traceback and the supporting laboratory investigations. PMID:17553250

Pavlin, Boris I.; Albariño, Cesar G.; Comer, James A.; Erickson, Bobbie R.; Oliver, Jennifer B.; Sealy, Tara K.; Vincent, Martin J.; Nichol, Stuart T.; Paddock, Christopher D.; Tumpey, Abbigail J.; Wagoner, Kent D.; Glauer, R. David; Smith, Kathleen A.; Winpisinger, Kim A.; Parsely, Melody S.; Wyrick, Phil; Hannafin, Christopher H.; Bandy, Utpala; Zaki, Sherif; Rollin, Pierre E.; Ksiazek, Thomas G.

2007-01-01

220

Experimental infections by Brucella suis type 4 in Alaskan rodents.  

PubMed

The susceptibility of nine species of rodents and one species of lagomorph to Brucella suis type 4 was studied experimentally. The rodent species included: guinea pig (Cavia porcellus), Scandinavian lemming (Lemmus lemmus), brown lemming (L. sibiricus), northern red-backed vole (Clethrionomys rutilis), varying lemmings (Dicrostonyx stevensoni and D. rubricatus), yellow-cheeked vole (Microtus xanthognathus), flying squirrel (Glaucomys sabrinus) and ground squirrel (Citellus parryii). The lagomorph, Lepus americanus (varying hare), was also studied. All of these species were readily infected by intraperitoneal inoculations of brucellae. Pathologic responses were not marked in most of these species. However, both species of varying lemmings responded dramatically to infections initiated by about as few as two cfu. All individuals of both species that were not killed eventually died from the infection. PMID:7463596

Miller, L G; Neiland, K A

1980-10-01

221

Hantavirus Infection in Humans and Rodents, Northwestern Argentina  

PubMed Central

We initiated a study to elucidate the ecology and epidemiology of hantavirus infections in northern Argentina. The northwestern hantavirus pulmonary syndrome (HPS)–endemic area of Argentina comprises Salta and Jujuy Provinces. Between 1997 and 2000, 30 HPS cases were diagnosed in Jujuy Province (population 512,329). Most patients had a mild clinical course, and the death rate (13.3%) was low. We performed a serologic and epidemiologic survey in residents of the area, in conjunction with a serologic study in rodents. The prevalence of hantavirus antibodies in the general human population was 6.5%, one of the highest reported in the literature. No evidence of interhuman transmission was found, and the high prevalence of hantavirus antibody seemed to be associated with the high infestation of rodents detected in domestic and peridomestic habitats. PMID:14519242

Levis, Silvana; Calderón, Gladys; Ramirez, Josefina; Bravo, Daniel; Lozano, Elena; Ripoll, Carlos; St. Jeor, Stephen; Ksiazek, Thomas G.; Barquez, Ruben M.; Enria, Delia

2003-01-01

222

Susceptibility of selected rodent species from Colorado to Borrelia burgdorferi.  

PubMed

To determine the susceptibility of some common Colorado (USA) rodent species to Borrelia burgdorferi, pregnant Peromyscus maniculatus, Tamias minimus, and Spermophilus lateralis were trapped in May 1990 and kept in quarantine until their young were old enough to be used in the experiment. Six to eight 8-wk-old individuals of each of the Colorado species and, for comparison, eight laboratory raised P. leucopus were subcutaneously inoculated with > or = 10(5) spirochetes in 0.1 ml in July 1990. Tissue specimens were collected for isolation from these animals through April 1991. Spirochetes were isolated from blood, ear, bladder, kidney, spleen, liver, and eye in Barbour-Stoener-Kelly (BSK) medium from P. maniculatus, P. leucopus and T. minimus. Spirochetes were isolated from at least one tissue from all of these animals and no isolations were obtained from any of the S. lateralis. Thus, three of the four rodent species tested are susceptible to, and could harbor, B. burgdorferi. PMID:8722268

Ubico, S R; McLean, R G; Cooksey, L M

1996-04-01

223

Hantavirus Immunology of Rodent Reservoirs: Current Status and Future Directions  

PubMed Central

Hantaviruses are hosted by rodents, insectivores and bats. Several rodent-borne hantaviruses cause two diseases that share many features in humans, hemorrhagic fever with renal syndrome in Eurasia or hantavirus cardiopulmonary syndrome in the Americas. It is thought that the immune response plays a significant contributory role in these diseases. However, in reservoir hosts that have been closely examined, little or no pathology occurs and infection is persistent despite evidence of adaptive immune responses. Because most hantavirus reservoirs are not model organisms, it is difficult to conduct meaningful experiments that might shed light on how the viruses evade sterilizing immune responses and why immunopathology does not occur. Despite these limitations, recent advances in instrumentation and bioinformatics will have a dramatic impact on understanding reservoir host responses to hantaviruses by employing a systems biology approach to identify important pathways that mediate virus/reservoir relationships. PMID:24638205

Schountz, Tony; Prescott, Joseph

2014-01-01

224

Hantavirus immunology of rodent reservoirs: current status and future directions.  

PubMed

Hantaviruses are hosted by rodents, insectivores and bats. Several rodent-borne hantaviruses cause two diseases that share many features in humans, hemorrhagic fever with renal syndrome in Eurasia or hantavirus cardiopulmonary syndrome in the Americas. It is thought that the immune response plays a significant contributory role in these diseases. However, in reservoir hosts that have been closely examined, little or no pathology occurs and infection is persistent despite evidence of adaptive immune responses. Because most hantavirus reservoirs are not model organisms, it is difficult to conduct meaningful experiments that might shed light on how the viruses evade sterilizing immune responses and why immunopathology does not occur. Despite these limitations, recent advances in instrumentation and bioinformatics will have a dramatic impact on understanding reservoir host responses to hantaviruses by employing a systems biology approach to identify important pathways that mediate virus/reservoir relationships. PMID:24638205

Schountz, Tony; Prescott, Joseph

2014-01-01

225

Climate change ecology: Tropical languor  

NASA Astrophysics Data System (ADS)

Carbon dioxide can stimulate photosynthesis in trees and increase their growth rates. A study of tree rings from three seasonal tropical forests shows no evidence of faster growth during 150 years of increasing atmospheric CO2 concentrations.

Cernusak, Lucas A.

2015-01-01

226

Tropical Cyclones and Climate Change  

E-print Network

Whether the characteristics of tropical cyclones have changed or will change in a warming climate — and if so, how — has been the subject of considerable investigation, often with conflicting results. Large amplitude ...

Knutson, Thomas R.

227

Deforestation: Tropical Forests in Decline  

NSDL National Science Digital Library

The Canadian International Development Agency has placed online a draft report entitled "Deforestation: Tropical Forests in Decline." The report examines "the extent of deforestation in developing countries, its causes and consequences, and prospect of more sustainable land use alternatives."

228

Estrogen attenuates HSP 72 expression in acutely exercised male rodents  

Microsoft Academic Search

Estrogen has been shown to reduce post-exercise skeletal muscle damage. Exercise-induced muscle damage may be a factor in the elevated post-exercise expression of heat-shock proteins (HSPs). Thus, the present investigation was conducted in order to examine the influence of estrogen on post-exercise levels of HSP 72 and heat-shock cognate, HSC 73, in male and female rodents. Prior to an acute

Zain Paroo; Peter M. Tiidus; Earl G. Noble

1999-01-01

229

Transmission Study of Andes Hantavirus Infection in Wild Sigmodontine Rodents  

PubMed Central

Our study was designed to contribute to an understanding of the timing and conditions under which transmission of Andes hantavirus in Oligoryzomys longicaudatus reservoir populations takes place. Mice were caged in test habitats consisting of steel drums containing holding cages, where seronegative rodents were exposed to wild seropositive individuals by freely sharing the same cage or being separated by a wire mesh. Tests were also performed for potential viral transmission to mice from excrement-tainted bedding in the cages. Andes virus transmitted efficiently; from 130 attempts with direct contact, 12.3% resulted in virus transmission. However, if we consider only those rodents that proved to be infectious, from 93 attempts we obtained 16 infected animals (17.2%). Twelve of them resulted from intraspecies O. longicaudatus encounters where male mice were differentially affected and 4 resulted from O. longicaudatus to Abrothrix olivaceus. Experiments using Abrothrix longipilis as receptors were not successful. Transmission was not observed between wire mesh-separated animals, and mice were not infected from excrement-tainted bedding. Bites seemed not to be a requisite for oral transmission. Genomic viral RNA was amplified in two out of three saliva samples from seropositive rodents, but it was not detected in urine samples obtained by vesicle puncture from two other infected rodents. Immunohistochemistry, using antibodies against Andes (AND) hantavirus proteins, revealed strong reactions in the lung and salivary glands, supporting the possibility of oral transmission. Our study suggests that AND hantavirus may be principally transmitted via saliva or saliva aerosols rather than via feces and urine. PMID:15479837

Padula, P.; Figueroa, R.; Navarrete, M.; Pizarro, E.; Cadiz, R.; Bellomo, C.; Jofre, C.; Zaror, L.; Rodriguez, E.; Murúa, R.

2004-01-01

230

PHYLOGENETICS OF THE NEW WORLD RODENT FAMILY HETEROMYIDAE  

Microsoft Academic Search

The family Heteromyidae includes 6 genera of rodents traditionally placed in 3 subfamilies endemic to the Nearctic and northern Neotropical biogeographic regions. Although several of these taxa represent intensively studied members of North and Central American ecosystems (e.g., kangaroo rats and pocket mice), phylogenetic relationships within and among subfamilies, genera, and species-groups are not well understood. Here, we used maximum-likelihood,

Lois F. Alexander; Brett R. Riddle

2005-01-01

231

Neural Representation of Spatial Topology in the Rodent Hippocampus  

PubMed Central

Pyramidal cells in the rodent hippocampus often exhibit clear spatial tuning in navigation. Although it has been long suggested that pyramidal cell activity may underlie a topological code rather than a topographic code, it remains unclear whether an abstract spatial topology can be encoded in the ensemble spiking activity of hippocampal place cells. Using a statistical approach developed previously, we investigate this question and related issues in greater details. We recorded ensembles of hippocampal neurons as rodents freely foraged in one and two-dimensional spatial environments, and we used a “decode-to-uncover” strategy to examine the temporally structured patterns embedded in the ensemble spiking activity in the absence of observed spatial correlates during periods of rodent navigation or awake immobility. Specifically, the spatial environment was represented by a finite discrete state space. Trajectories across spatial locations (“states”) were associated with consistent hippocampal ensemble spiking patterns, which were characterized by a state transition matrix. From this state transition matrix, we inferred a topology graph that defined the connectivity in the state space. In both one and two-dimensional environments, the extracted behavior patterns from the rodent hippocampal population codes were compared against randomly shuffled spike data. In contrast to a topographic code, our results support the efficiency of topological coding in the presence of sparse sample size and fuzzy space mapping. This computational approach allows us to quantify the variability of ensemble spiking activity, to examine hippocampal population codes during off-line states, and to quantify the topological complexity of the environment. PMID:24102128

Chen, Zhe; Gomperts, Stephen N.; Yamamoto, Jun; Wilson, Matthew A.

2014-01-01

232

Defensive burying in rodents: ethology, neurobiology and psychopharmacology  

Microsoft Academic Search

Defensive burying refers to the typical rodent behavior of displacing bedding material with vigorous treading-like movements of their forepaws and shoveling movements of their heads directed towards a variety of noxious stimuli that pose a near and immediate threat, such as a wall-mounted electrified shock-prod. Since its introduction 25 years ago by Pinel and Treit [J. Comp. Physiol. Psychol. 92

Sietse F. De Boer; Jaap M. Koolhaas

2003-01-01

233

Seasonal activity patterns of rodents in a sagebrush community  

Microsoft Academic Search

Twelve species of nocturnal rodents were studied on a 2.7-hectare plot of sagebrush desert in west-central Nevada. Six species, Dipodomys merriami, D. ordii, D. panamintinus, D. microps, Onychomys torridus, and Peromyscus maniculatus, were active throughout the year. Four species, Perognathus longimembris, P. formosus, Microdipodops megacephalus, and Reithrodontomys megalotis, hibernated and were active only in spring, summer, and autumn. Onychomys leucogaster

OFarrell

1974-01-01

234

USING SURVIVAL OF RODENTS TO ASSESS QUALITY OF PRAIRIE HABITATS  

Microsoft Academic Search

ABSTRACT—Estimates of abundance,commonly,are used,for assessing quality of wildlife habitat. However, disparities between abundance and fitness parameters make the utility of abundance for predicting quality of habitat questionable. We used survival of rodents and rates of capture to assess quality of habitat in greasewood,scrub and sandhill prairie habitats at the United States Army Pueblo Chemical Depot, Pueblo, Colorado. Only the Ord’s

Robert A. Schorr; Jeremy L. Siemers; Paul M. Lukacs; James P. Gionfriddo; John R. Sovell; Renee J. Rondeau; Michael B. Wunder

2007-01-01

235

A functional analysis of circadian pacemakers in nocturnal rodents  

Microsoft Academic Search

Summary 1.The circadian pacemakers controlling activity rhythms in four species of rodents are compared, as freerunning systems in constant darkness. In analyzing their stability the distinction is made between (1) spontaneous day-to-day instability of frequency, and (2) a longer-term lability, some of which is traceable to identified causes.2.Serial correlation analysis indicates that the precision (day-to-day stability) of the pacemaker's period

Colin S. Pittendrigh; Serge Daan

1976-01-01

236

Ventilatory accommodation of changing oxygen demand in sciurid rodents  

Microsoft Academic Search

Ventilation was measured across a range of O2 consumption rates in four sciurid rodents: Tamias minimus (47 g), Spermophilus lateralis (189 g), S. beecheyi (531 g), and Marmota flaviventris juveniles (1054 g) and adults (2989 g). Maximum thermogenic oxygen consumption was measured for all but adult M. flaviventris. Aerobic scopes (maximum\\/minimum O2 consumption rates) were 4.6, 3.8, 5.4, and 4.8

Mark A. Chappell

1992-01-01

237

Early Miocene rodents and insectivores from northeastern Colorado  

E-print Network

THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS VE RTE B RATA ARTICLE 7 Pages 1-92, Figures 1-131 EARLY MIOCENE RODENTS AND INSECTIVORES FROM NORTHEASTERN COLORADO By ROBERT W. WILSON ARTICLE 8 Pages 1-24, Figures 1-21 A NEW ARMORED DINOSAUR... AND INSECTIVORES FROM NORTHEASTERN COLORADO By ROBERT W. WILSON (Contribution from the Museum of Natural History) THE UNIVERSITY OF KANSAS PUBLICATIONS November 21, 1960 PRINTED BY THE UNIVERSITY OF KANSAS PRESS LAWRENCE THE UNIVERSITY OF KANSAS PALEONTOLOGICAL...

Wilson, R. W.

1960-11-21

238

Telomerase protects adult rodent olfactory ensheathing glia from early senescence.  

PubMed

Adult olfactory bulb ensheathing glia (OB-OEG) promote the repair of acute, subacute, and chronic spinal cord injuries and autologous transplantation is a feasible approach. There are interspecies differences between adult rodent and primate OB-OEG related to their longevity in culture. Whereas primate OB-OEG exhibit a relatively long life span, under the same culture conditions rodent OB-OEG divide just three to four times, are sensitive to oxidative stress and become senescent after the third week in vitro. Telomerase is a "physiological key regulator" of the life span of normal somatic cells and also has extratelomeric functions such as increased resistance to oxidative stress. To elucidate whether telomerase has a role in the senescence of rodent OB-OEG, we have introduced the catalytic subunit of telomerase mTERT into cultures of these cells by retroviral infection. Native and modified adult rat OB-OEG behaved as telomerase-competent cells as they divided while expressing mTERT but entered senescence once the gene switched off. After ectopic expression of mTERT, OB-OEG resumed division at a nonsenescent rate, expressed p75 and other OEG markers, and exhibited the morphology of nonsenescent OB-OEG. The nonsenescent period of mTERT-OEG lasted 9weeks and then ectopic mTERT switched off and cells entered senescence again. Our results suggest a role of telomerase in early senescence of adult rodent OB-OEG cultures and a protection from oxidative damage. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair. PMID:20736004

Llamusí, María-Beatriz; Rubio, Mari-Paz; Ramón-Cueto, Almudena

2011-05-01

239

Enteric pathogens in tropical aquaria.  

PubMed

A total of 100 tropical aquaria from six pet shops were sampled for the presence of Salmonella, Campylobacter and Aeromonas species. Eight fish tanks contained unusual serotypes of salmonella. None had been used to house terrapins. One hundred and three isolates of Aeromonas species were obtained from 98 tanks. One tank contained Plesiomonas shigelloides. No Campylobacter species were isolated. It is suggested that a tropical aquarium may constitute an infection hazard. PMID:3428370

Sanyal, D; Burge, S H; Hutchings, P G

1987-12-01

240

Detection of newly recognized rodent parvoviruses by PCR.  

PubMed Central

Several autonomous parvovirus isolates distinct from the prototypic rodent parvoviruses have recently been identified. These include variants of a mouse orphan parvovirus (MOPV) and a hamster isolate designated hamster orphan parvovirus (HOPV). In this study, a PCR primer set specific for these newly identified rodent parvoviruses was designed on the basis of DNA sequence comparisons of these isolates with other autonomous parvoviruses. The specificity of the primer set was determined by testing viral preparations of seven different parvoviruses and eight other viruses known to infect rodents. The PCR assay amplified the expected 260-bp product only in the presence of DNA from MOPV, HOPV, or LuIII a parvovirus of unknown species origin. The assay was able to detect as little as 10 pg of MOPV viral DNA or 1 pg of HOPV viral DNA, and it was able to detect MOPV in tissues from naturally infected mice and HOPV in tissues from experimentally infected hamsters. In contrast, the 260-bp product was not amplified from tissues of MOPV-negative mice or mock-infected hamsters. Our findings indicate that this PCR assay provides a rapid, specific, and sensitive method for the detection of MOPV in mice, HOPV in hamsters, and MOPV and HOPV in cell culture systems and that it may also be useful for the detection of LuIII contamination of cell culture systems. PMID:8576334

Besselsen, D G; Besch-Williford, C L; Pintel, D J; Franklin, C L; Hook, R R; Riley, L K

1995-01-01

241

Thermophysiological responses to hyperthermic drugs: extrapolating from rodent to human.  

PubMed

This chapter focuses on the effects of hyperthermia on drug and chemical toxicity. In general, hyperthermia exacerbates the toxicity of many types of drugs and environmental toxicants. Using rodents to model the potential responses of humans to hyperthermic drugs is hampered by the unique differences in thermoregulatory ability and body mass. Because of their relatively large surface area:mass ratio, ambient temperature has a more profound influence on the potential hyperthermic effect of a drug in rodents. The relative increase in heat production (i.e., as a percentage of their basal metabolic rate) required to raise core temperature by 1 degrees C will increase with a decrease in body mass. The thermoregulatory response to methylenedioxymethamphetamine (MDMA) is used to illustrate the differences in thermoregulatory responses of rats and humans to a hyperthermic drug. Overall, the interaction between ambient temperature and drug-induced changes in body temperature is critical in the evaluation of hyperthermic-induced toxicity in rodent models. PMID:17645915

Gordon, Christopher J

2007-01-01

242

Rodent Facial Nerve Recovery After Selected Lesions and Repair Techniques  

PubMed Central

Background Measuring rodent facial movements is a reliable method for studying recovery from facial nerve manipulation, and for examining the behavioral correlates of aberrant regeneration. We quantitatively compared recovery of vibrissal and ocular function following three types of clinically relevant nerve injury. Methods 178 adult rats underwent facial nerve manipulation and testing. In the experimental groups, the left facial nerve was either crushed, transected and repaired epineurially, or transected and the stumps suture-secured into a tube with a 2 mm gap between them. Facial recovery was measured for the ensuing 1–4 months. Data were analyzed for whisking recovery. Previously developed markers of co-contraction of the upper and midfacial zones (possible synkinesis markers) were also examined. Results Animals in the crush groups recovered nearly normal whisking parameters within 25 days. The distal branch crush group showed improved recovery over the main trunk crush group for several days during early recovery. By week 9, the transection/repair groups showed evidence of recovery that trended further upward throughout the study period. The entubulation groups followed a similar recovery pattern, though they did not maintain significant recovery levels by the study conclusion. Markers of potential synkinesis increased in selected groups following facial nerve injury. Conclusions Rodent vibrissial function recovers in a predictable fashion following manipulation. Generalized co-contraction of the upper and midfacial zones emerges following facial nerve manipulation, possibly related to aberrant regeneration, polyterminal axons, or hypersensitivity of the rodent to sensory stimuli following nerve manipulation. PMID:20048604

Hadlock, Tessa A.; Kowaleski, Jeffrey; Lo, David; Mackinnon, Susan E.; Heaton, James T.

2015-01-01

243

Towards an integrative model of sociality in caviomorph rodents  

PubMed Central

In the late 1990s and early 2000s it was recognized that behavioral ecologists needed to study the sociality of caviomorph rodents (New World hystricognaths) before generalizations about rodent sociality could be made. Researchers identified specific problems facing individuals interested in caviomorph sociality, including a lack of information on the proximate mechanisms of sociality, role of social environment in development, and geographical or intraspecific variation in social systems. Since then researchers have described the social systems of many previously understudied species, including some with broad geographical ranges. Researchers have done a good job of determining the role of social environments in development and identifying the costs and benefits of social living. However, relatively little is known about the proximate mechanisms of social behavior and fitness consequences, limiting progress toward the development of integrative (evolutionary-mechanistic) models for sociality. To develop integrative models behavioral ecologists studying caviomorph rodents must generate information on the fitness consequences of different types of social organization, brain mechanisms, and endocrine substrates of sociality. We review our current understanding and future directions for research in these conceptual areas. A greater understanding of disease ecology, particularly in species carrying Old World parasites, is needed before we can identify potential links between social phenotypes, mechanism, and fitness. PMID:22328791

Hayes, Loren D.; Burger, Joseph Robert; Soto-Gamboa, Mauricio; Sobrero, Raúl; Ebensperger, Luis A

2012-01-01

244

Rodent Models of Depression: Neurotrophic and Neuroinflammatory Biomarkers  

PubMed Central

Rodent models are an indispensable tool for studying etiology and progress of depression. Since interrelated systems of neurotrophic factors and cytokines comprise major regulatory mechanisms controlling normal brain plasticity, impairments of these systems form the basis for development of cerebral pathologies, including mental diseases. The present review focuses on the numerous experimental rodent models of depression induced by different stress factors (exteroceptive and interoceptive) during early life (including prenatal period) or adulthood, giving emphasis to the data on the changes of neurotrophic factors and neuroinflammatory indices in the brain. These parameters are closely related to behavioral depression-like symptoms and impairments of neuronal plasticity and are both gender- and genotype-dependent. Stress-related changes in expression of neurotrophins and cytokines in rodent brain are region-specific. Some contradictory data reported by different groups may be a consequence of differences of stress paradigms or their realization in different laboratories. Like all experimental models, stress-induced depression-like conditions are experimental simplification of clinical depression states; however, they are suitable for understanding the involvement of neurotrophic factors and cytokines in the pathogenesis of the disease—a goal unachievable in the clinical reality. These major regulatory systems may be important targets for therapeutic measures as well as for development of drugs for treatment of depression states. PMID:24999483

Stepanichev, Mikhail; Dygalo, Nikolay N.; Grigoryan, Grigory; Shishkina, Galina T.; Gulyaeva, Natalia

2014-01-01

245

Mycobacterium microti Infection (Vole Tuberculosis) in Wild Rodent Populations  

PubMed Central

Mycobacterium microti (vole tuberculosis) infections in small wild mammals were first described more than 60 years ago in several populations in Great Britain. Few studies of vole tuberculosis have been undertaken since then, and little is known about the relationship between M. microti isolates originating from different populations or at different times or of the prevalence of this infection in wild rodent populations, despite human cases of M. microti infections being increasingly reported. In this study, field voles (Microtus agrestis), bank voles (Clethrionomys glareolus), and wood mice (Apodemus sylvaticus) were found to be infected, with up to 8% having external tuberculous signs, in wild populations in Northumberland and Cheshire, England. Spoligotyping applied directly to the clinical material simultaneously detected and typed M. microti bacteria in skin lesions, lymph glands, and internal abcesses. IS6110 restriction fragment length polymorphism typing of cultured bacteria was used to compare these isolates with previously isolated strains from both animals and humans. This demonstrated that although the current rodent isolates were distinct from those isolated from voles in the 1930s in Great Britain, they had a high degree of similarity to these strains and were distinct from the M. microti isolates from humans, a pig, and a ferret from The Netherlands. Thus, M. microti infection seems to be widespread in wild rodent populations, but more studies are needed to understand how M. microti might be transmitted from animals to humans and to determine better the zoonotic risk posed. PMID:12202566

Cavanagh, Rachel; Begon, Michael; Bennett, Malcolm; Ergon, Torbjørn; Graham, Isla M.; de Haas, Petra E. W.; Hart, C. A.; Koedam, Marianne; Kremer, Kristin; Lambin, Xavier; Roholl, Paul; Soolingen, Dick van

2002-01-01

246

Results from a Survey of Current Practices for Sampling of Nervous System in Rodents and Non-rodents in General Toxicity Studies  

EPA Science Inventory

A survey of current practices for sampling and examination of the nervous system in rodents and non-rodents for general and neurotoxicity (NT) studies was conducted by the Nervous System Sampling Subcommittee of the STP. For general toxicity studies most of those surveyed (>63%) ...

247

Evidence for rodent-common and species-typical limb and digit use in eating, derived from a comparative analysis of ten rodent species  

Microsoft Academic Search

Order Rodentia comprises a vast portion of mammalian species (1814 species), which occupy extremely diverse habitats requiring very distinct motor specializations (e.g. burrowing, hopping, climbing, flying and swimming). Although early classification of paw use ability suggests rodents are impoverished relative to primates and make little use of their paws, there have been no systematic investigations of paw use in rodents.

I. Q. Whishaw; J. R. Sarna; S. M. Pellis

1998-01-01

248

The role of rodents and shrews in the transmission of Toxoplasma gondii to pigs.  

PubMed

Inadequate rodent control is considered to play a role in Toxoplasma gondii infection of pigs. This issue was addressed in the current study by combining a 4-month rodent control campaign and a 7-month longitudinal analysis of T. gondii seroprevalence in slaughter pigs. Three organic pig farms with known rodent infestation were included in the study. On these farms, presence of T. gondii in trapped rodents was evaluated by real-time PCR. All rodent species and shrews investigated had T. gondii DNA in brain or heart tissue. Prevalence was 10.3% in Rattus norvegicus, 6.5% in Mus musculus, 14.3% in Apodemus sylvaticus and 13.6% in Crocidura russula. Initial T. gondii seroprevalence in the slaughter pigs ranged between 8% and 17% and dropped on the three farms during the rodent control campaign to 0-10%, respectively. After 4 months of rodent control, T. gondii infection was absent from pigs from two of the three farms investigated and appeared again in one of those two farms after the rodent control campaign had stopped. This study emphasizes the role of rodents and shrews in the transmission of T. gondii to pigs and the importance of rodent control towards production of T. gondii-free pig meat. PMID:18606498

Kijlstra, Aize; Meerburg, Bastiaan; Cornelissen, Jan; De Craeye, Stéphane; Vereijken, Pieter; Jongert, Erik

2008-10-01

249

Recognition and management of rodent-borne infectious disease outbreaks after heavy rainfall and flooding.  

PubMed

Climatic events, especially heavy rains and flooding following periods of relative drought, have precipitated both arthropod-borne and rodent-borne infectious disease outbreaks. Heavy rainfall encourages excessive wild grass seed production that supports increased outdoor rodent populations, and flooding forces rodents from their burrows near water sources into the built environment and closer to humans. The objectives of this review are to alert clinicians to the climatic conditions common to hurricane-prone regions, such as Louisiana, that can precipitate outbreaks of the two rodent-borne diseases most often associated with periods of heavy rainfall and flooding, leptospirosis (LS) and hantavirus pulmonary syndrome (HPS). It will also describe the epidemiology, presenting clinical manifestations and outcomes of these rodent-borne infectious diseases, and recommend both prophylactic therapies and effective control and prevention strategies for rodent-borne infectious disease outbreaks. Healthcare providers should maintain high levels of suspicion for LS in patients developing febrile illnesses after contaminated freshwater exposures during flooding or recreational events, and for HPS in patients with febrile illnesses that progress rapidly to respiratory failure following rodent exposures in enclosed spaces. Public health educational strategies should encourage limiting human contact with all wild and peridomestic rats and mice, avoiding all contact with rodent excreta, safely disposing of all rodent excreta, and modifying the built environment to deter rodents from colonizing households and workplaces. PMID:25369218

Diaz, James H

2014-01-01

250

Tropical Cyclone Gonu  

NASA Technical Reports Server (NTRS)

You might expect to see a storm with near-perfect symmetry and a well-defined eye hovering over the warm waters of the Caribbean or in the South Pacific, but Tropical Cyclone Gonu showed up in an unusual place. On June 4, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite captured this image, Tropical Cyclone Gonu was approaching the northeastern shore of Oman, a region better known for hot desert conditions. Though rare, cyclones like Gonu are not unheard of in the northern Indian Ocean basin. Most cyclones that form in the region form over the Bay of Bengal, east of India. Those that take shape over the Arabian Sea, west of the Indian peninsula, tend to be small and fizzle out before coming ashore. Cyclone Gonu is a rare exception. As of June 4, 2007, the powerful storm had reached a dangerous Category Four status, and it was forecast to graze Oman's northeastern shore, following the Gulf of Oman. According to storm statistics maintained on Unisys Weather, the last storm of this size to form over the Arabian Sea was Cyclone 01A, which tracked northwest along the coast of India between May 21 and May 28, 2001. Unlike Gonu's forecasted track, Cyclone 01A never came ashore. MODIS acquired this photo-like image at 12:00 p.m. local time (9:00 UTC), a few hours after the Joint Typhoon Warning Center estimated Gonu's sustained winds to be over 240 kilometers per hour (145 miles per hour). The satellite image confirms that Gonu was a super-powerful cyclone. The storm has the hallmark tightly wound arms that spiral around a well-defined, circular eye. The eye is surrounded by a clear wall of towering clouds that cast shadows on the surrounding clouds. Called hot towers, these clouds are a sign of the powerful uplift that feeds the storm. The symmetrical spirals, clear eye, and towering clouds are all features regularly seen in satellite images of other particularly powerful cyclones, which are also known as typhoons or hurricanes when they form in other parts of the world. The high-resolution image provided above is at MODIS' full spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response System provides this image at additional resolutions.

2007-01-01

251

Forest rodents provide directed dispersal of Jeffrey pine seeds.  

PubMed

Some species of animals provide directed dispersal of plant seeds by transporting them nonrandomly to microsites where their chances of producing healthy seedlings are enhanced. We investigated whether this mutualistic interaction occurs between granivorous rodents and Jeffrey pine (Pinus jeffreyi) in the eastern Sierra Nevada by comparing the effectiveness of random abiotic seed dispersal with the dispersal performed by four species of rodents: deer mice (Peromyscus maniculatus), yellow-pine and long-eared chipmunks (Tamias amoenus and T. quadrimaculatus), and golden-mantled ground squirrels (Spermophilus lateralis). We conducted two caching studies using radio-labeled seeds, the first with individual animals in field enclosures and the second with a community of rodents in open forest. We used artificial caches to compare the fates of seeds placed at the range of microsites and depths used by animals with the fates of seeds dispersed abiotically. Finally, we examined the distribution and survival of naturally establishing seedlings over an eight-year period. Several lines of evidence suggested that this community of rodents provided directed dispersal. Animals preferred to cache seeds in microsites that were favorable for emergence or survival of seedlings and avoided caching in microsites in which seedlings fared worst. Seeds buried at depths typical of animal caches (5-25 mm) produced at least five times more seedlings than did seeds on the forest floor. The four species of rodents differed in the quality of dispersal they provided. Small, shallow caches made by deer mice most resembled seeds dispersed by abiotic processes, whereas many of the large caches made by ground squirrels were buried too deeply for successful emergence of seedlings. Chipmunks made the greatest number of caches within the range of depths and microsites favorable for establishment of pine seedlings. Directed dispersal is an important element of the population dynamics of Jeffrey pine, a dominant tree species in the eastern Sierra Nevada. Quantifying the occurrence and dynamics of directed dispersal in this and other cases will contribute to better understanding of mutualistic coevolution of plants and animals and to more effective management of ecosystems in which directed dispersal is a keystone process. PMID:19341138

Briggs, Jennifer S; Vander Wall, Stephen B; Jenkins, Stephen H

2009-03-01

252

Forest rodents provide directed dispersal of Jeffrey pine seeds  

USGS Publications Warehouse

Some species of animals provide directed dispersal of plant seeds by transporting them nonrandomly to microsites where their chances of producing healthy seedlings are enhanced. We investigated whether this mutualistic interaction occurs between granivorous rodents and Jeffrey pine (Pinus Jeffreyi) in the eastern Sierra Nevada by comparing the effectiveness of random abiotic seed dispersal with the dispersal performed by four species of rodents: deer mice (Peromyscus maniculatus), yellow-pine and long-eared chipmunks (Tamias amoenus and T. quadrimaculatus), and golden-mantled ground squirrels (Spermophilus lateralis). We conducted two caching studies using radio-labeled seeds, the first with individual animals in field enclosures and the second with a community of rodents in open forest. We used artificial caches to compare the fates of seeds placed at the range of microsites and depths used by animals with the fates of seeds dispersed abiotically. Finally, we examined the distribution and survival of naturally establishing seedlings over an eight-year period. Several lines of evidence suggested that this community of rodents provided directed dispersal. Animals preferred to cache seeds in microsites that were favorable for emergence or survival of seedlings and avoided caching in microsites in which seedlings fared worst. Seeds buried at depths typical of animal caches (5-25 mm) produced at least five times more seedlings than did seeds on the forest floor. The four species of rodents differed in the quality of dispersal they provided. Small, shallow caches made by deer mice most resembled seeds dispersed by abiotic processes, whereas many of the large caches made by ground squirrels were buried too deeply for successful emergence of seedlings. Chipmunks made the greatest number of caches within the range of depths and microsites favorable for establishment of pine seedlings. Directed dispersal is an important element of the population dynamics of Jeffrey pine, a dominant tree species in the eastern Sierra Nevada. Quantifying the occurrence and dynamics of directed dispersal in this and other cases will contribute to better understanding of mutualistic coevolution of plants and animals and to more effective management of ecosystems in which directed dispersal is a keystone process. ?? 2009 by the Ecological society of America.

Briggs, J.S.; Wall, S.B.V.; Jenkins, S.H.

2009-01-01

253

Transitions between Andean and Amazonian centers of endemism in the radiation of some arboreal rodents  

PubMed Central

Background The tropical Andes and Amazon are among the richest regions of endemism for mammals, and each has given rise to extensive in situ radiations. Various animal lineages have radiated ex situ after colonizing one of these regions from the other: Amazonian clades of dendrobatid frogs and passerine birds may have Andean ancestry, and transitions from the Amazon to Andes may be even more common. To examine biogeographic transitions between these regions, we investigated the evolutionary history of three clades of rodents in the family Echimyidae: bamboo rats (Dactylomys-Olallamys-Kannabateomys), spiny tree-rats (Mesomys-Lonchothrix), and brush-tailed rats (Isothrix). Each clade is distributed in both the Andes and Amazonia, and is more diverse in the lowlands. We used two mitochondrial (cyt-b and 12S) and three nuclear (GHR, vWF, and RAG1) markers to reconstruct their phylogenetic relationships. Tree topologies and ancestral geographic ranges were then used to determine whether Andean forms were basal to or derived from lowland radiations. Results Four biogeographic transitions are identified among the generic radiations. The bamboo rat clade unambiguously originated in the Amazon ca. 9 Ma, followed by either one early transition to the Andes (Olallamys) and a later move to the Amazon (Dactylomys), or two later shifts to the Andes (one in each genus). The Andean species of both Dactylomys and Isothrix are sister to their lowland species, raising the possibility that highland forms colonized the Amazon Basin. However, uncertainty in their reconstructed ancestral ranges obscures the origin of these transitions. The lone Andean species of Mesomys is confidently nested within the lowland radiation, thereby indicating an Amazon-to-Andes transition ca. 2 Ma. Conclusions Differences in the timing of these biogeographic transitions do not appear to explain the different polarities of these trees. Instead, even within the radiation of a single family, both Andean and Amazonian centers of endemism appear enriched by lineages that originated in the other region. Our survey of other South American lineages suggests a pattern of reciprocal exchange between these regions—among mammals, birds, amphibians, and insects we found no fewer than 87 transitions between the Andes and Amazon from Miocene-Pleistocene. Because no clear trend emerges between the timing and polarity of transitions, or in their relative frequency, we suggest that reciprocal exchange between tropical highland and lowland faunas in South America has been a continual process since ca. 12 Ma. PMID:24015814

2013-01-01

254

Antioxidants from tropical herbs.  

PubMed

Plants that contain high amounts of polyphenolic compounds are potential candidates for natural antioxidant sources. Studies are on going in the search for new sources of antioxidants. Not much data are available on the antioxidant capacity of tropical herbs. With this in mind, 19 commonly consumed Malaysian herbs were analyzed for their polyphenolic content and antioxidant activities. A majority of these plants have never been studied before with regards to their polyphenolic content and antioxidant activities. The shoots of Anacardium occidentale, the shoots and fruits of Barringtonia racemosa, Pithecellobium jiringa and Parkia speciosa had high polyphenolic contents (> 150 microg gallic acid equivalents/mg dried plant) and antioxidant activities when measured using the ferric reducing antioxidant power (FRAP) (>1.2 mM) and Trolox equivalent antioxidant capacity (TEAC) assays (>2.4 mM). A strong correlation was observed between the two antioxidant assays (FRAP vs TEAC) implying that the plants could both scavenge free radicals and reduce oxidants. There was also a strong correlation between the antioxidant activities and polyphenolic content suggesting the observed antioxidant activities were contributed mainly by the polyphenolics in the plants. PMID:20420325

Razab, Rasyidah; Abdul-Aziz, Azlina

2010-03-01

255

Linking human behaviour to environmental effects using a case study of urban rodent control  

Microsoft Academic Search

Pest control is common in many land use activities and can affect non?target species. Our objectives were to evaluate, among chemical rodent control product (rodenticide) users, awareness of non?target effects on wildlife and willingness to change rodent control behaviour given knowledge of possible local non?target effects. Approximately half of respondents to a resident survey in California (USA) practised rodent control;

Anita T. Morzillo; Angela G. Mertig

2011-01-01

256

The African lily Massonia depressa (Hyacinthaceae) the First Monocotyledon Discovered to be Pollinated by Rodents  

NSDL National Science Digital Library

A nocturnal rodent, Gerbilluris paeba, feeds on the copious amounts of jelly-like nectar produced by flowers of the African lily Massonia depressa (Hyacinthaceae). This lily, which has flowers situated at ground level, is the first monocotyledon discovered to be pollinated by rodents. The striking similarities between the flowers of M. depressa and those of unrelated rodent-pollinated Protea spp. (Proteaceae) provide strong support for the concept of convergent floral syndromes.

Anton Pauw (University of Cape Town, Department of Botany ADR; POSTAL)

2004-03-09

257

Structure in a desert rodent community: use of space around Dipodomys spectabilis mounds  

Microsoft Academic Search

In an earlier paper (Bowers et al. 1987) we reported patterns of microhabitat use by desert rodents among 0.25-ha plots where seeds were added or certain rodent species removed. We used the results to make inferences about the spatial organization of the whole rodent community. Here we change our focus to test for spatial usage patterns at a smaller (within-plot)

M. A. Bowers; J. H. Brown

1992-01-01

258

Characteristics associated with contact with rodents in, around, and outside homes in khon kaen province, Thailand.  

PubMed

Rodents are an important reservoir for zoonotic diseases. To enhance the evidence on the human-rodent interface, this cross-sectional study was conducted in 2011 to investigate characteristics associated with rodent contact in Khon Kaen Province, Thailand. A standardized, interviewer-administered questionnaire elicited information from 201 adults (101 males and 100 females). Overall, 86.6% of participants reported encountering or seeing evidence of rodents in or near the home, whereas 57.2% encountered rodents while working with crops. Encountering rodents in or near the home was positively associated with the number of agricultural activities, whereas encountering rodents during crop work was positively associated with perceiving that disease can be acquired from rodents, the number of food crops grown, the number of agricultural activities, and living in a house with wooden walls. Surprisingly, neither outcome was associated appreciably with gender, age, or setting (urban, forest, or agricultural). These results provide information on the potential risk of rodent-borne zoonoses; this evidence has implications for risk communication strategies in this province and likely elsewhere. PMID:25646260

Suwannarong, Kanokwan; Chapman, Robert S

2015-04-01

259

Mammary gland neoplasia in long-term rodent studies.  

PubMed Central

Breast cancer, the most frequent spontaneous malignancy diagnosed in women in the western world, is continuously increasing in incidence in industrialized nations. Although breast cancer develops in women as the result of a combination of external and endogenous factors such as exposure to ionizing radiation, diet, socioeconomic status, and endocrinologic, familial, or genetic factors, no specific etiologic agent(s) or the mechanisms responsible of the disease has been identified as yet. Thus, experimental models that exhibit the same complex interactions are needed for testing various mechanisms and for assessing the carcinogenic potential of given chemicals. Rodent mammary carcinomas represent such a model to a great extent because, in these species, mammary cancer is a multistep complex process that can be induced by either chemicals, radiation, viruses, or genetic factors. Long-term studies in rodent models have been particularly useful for dissecting the initiation, promotion, and progression steps of carcinogenesis. The susceptibility of the rodent mammary gland to develop neoplasms has made this organ a unique target for testing the carcinogenic potential of specific genotoxic chemicals and environmental agents. Mammary tumors induced by indirect- or direct-acting carcinogens such as 7, 12-dimethlbenz(a)anthracene or N-methyl-N-nitrosourea are, in general, hormone dependent adenocarcinomas whose incidence, number of tumors per animal, tumor latency, and tumor type are influenced by the age, reproductive history, and endocarinologic milieu of the host at the time of carcinogen exposure. Rodent models are informative in the absence of human data. They have provided valuable information on the dose and route of administration to be used and optimal host conditions for eliciting maximal tumorigenic response. Studies of the influence of normal gland development on the pathogenesis of chemically induced mammary carcinomas have clarified the role of differentiation in cancer initiation. Comparative studies with the development of the human breast and the pathogenesis of breast cancer have contributed to validate rodent-to-human extrapolations. However, it has not been definitively established what type of information is necessary for human risk assessment, whether currently toxicity testing methodologies are sufficient for fulfilling those needs, or whether treatment-induced tumorigenic responses in rodents are predictive of potential human risk. An alternative to the traditional bioassays are mechanism-based toxicology and molecular and cellular approaches, combined with comparative in vitro systems. These approaches might allow the rapid screen of chemicals for setting priorities for further studies to determine the dose-response relationship for chemical effects at low doses, to assess effects other than mutagenesis and/or tumorigenesis, or to establish qualitative and quantitative relationships of biomarkers to toxic effects. Until there is enough information on the predictive value of mechanism-based toxicology for risk assessment, this approach should be used in conjunction with and validated by the traditional in vivo long-term bioassays. Images Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. A Figure 7. B Figure 8. A Figure 8. B Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Figure 23. Figure 24. Figure 25. Figure 26. PMID:8899375

Russo, I H; Russo, J

1996-01-01

260

The Dynamics and Predictability of Tropical Cyclones  

E-print Network

Through methodology unique for tropical cyclones in peer-reviewed literature, this study explores how the dynamics of moist convection affects the predictability of tropical cyclogenesis. Mesoscale models are used to perform short-range ensemble...

Sippel, Jason A.

2010-01-15

261

Estimating tropical cyclone precipitation risk in Texas  

E-print Network

This paper uses a new rainfall algorithm to simulate the long-term tropical cyclone precipitation (TCP) climatology in Texas based on synthetic tropical cyclones generated from National Center for Atmospheric Research/National ...

Zhu, Laiyin

262

A Ventilation Index for Tropical Cyclones  

E-print Network

An important environmental control of both tropical cyclone intensity and genesis is vertical wind shear. One hypothesized pathway by which vertical shear affects tropical cyclones is midlevel ventilation—or the flux of ...

Tang, Brian

263

Midlevel Ventilation's Constraint on Tropical Cyclone Intensity  

E-print Network

Midlevel ventilation, or the flux of low-entropy air into the inner core of a tropical cyclone (TC), is a hypothesized mechanism by which environmental vertical wind shear can constrain a tropical cyclone’s intensity. An ...

Tang, Brian Hong-An

264

High Altitude Glaciers in the Tropics  

NSDL National Science Digital Library

While it may seem like a contradiction, glaciers do exist in the tropical latitudes. In this video produced by ThinkTV, learn about tropical glaciers and why scientists are studying them to better understand global climate change.

ThinkTV

2010-11-30

265

12.811 Tropical Meteorology, Spring 2005  

E-print Network

This course describes the behavior and dynamics of the tropical troposphere, from the large-scale energy balance down to cumulus convection and tropical cyclones. Topics include: Radiative-convective equilibrium; the Hadley ...

Emanuel, Kerry

266

Ghrelin Influences Novelty Seeking Behavior in Rodents and Men  

PubMed Central

Recent discoveries indicate an important role for ghrelin in drug and alcohol reward and an ability of ghrelin to regulate mesolimbic dopamine activity. The role of dopamine in novelty seeking, and the association between this trait and drug and alcohol abuse, led us to hypothesize that ghrelin may influence novelty seeking behavior. To test this possibility we applied several complementary rodent models of novelty seeking behavior, i.e. inescapable novelty-induced locomotor activity (NILA), novelty-induced place preference and novel object exploration, in rats subjected to acute ghrelin receptor (growth hormone secretagogue receptor; GHSR) stimulation or blockade. Furthermore we assessed the possible association between polymorphisms in the genes encoding ghrelin and GHSR and novelty seeking behavior in humans. The rodent studies indicate an important role for ghrelin in a wide range of novelty seeking behaviors. Ghrelin-injected rats exhibited a higher preference for a novel environment and increased novel object exploration. Conversely, those with GHSR blockade drastically reduced their preference for a novel environment and displayed decreased NILA. Importantly, the mesolimbic ventral tegmental area selective GHSR blockade was sufficient to reduce the NILA response indicating that the mesolimbic GHSRs might play an important role in the observed novelty responses. Moreover, in untreated animals, a striking positive correlation between NILA and sucrose reward behavior was detected. Two GHSR single nucleotide polymorphisms (SNPs), rs2948694 and rs495225, were significantly associated with the personality trait novelty seeking, as assessed using the Temperament and Character Inventory (TCI), in human subjects. This study provides the first evidence for a role of ghrelin in novelty seeking behavior in animals and humans, and also points to an association between food reward and novelty seeking in rodents. PMID:23227170

Hansson, Caroline; Shirazi, Rozita H.; Näslund, Jakob; Vogel, Heike; Neuber, Corinna; Holm, Göran; Anckarsäter, Henrik; Dickson, Suzanne L.; Eriksson, Elias; Skibicka, Karolina P.

2012-01-01

267

Ghrelin influences novelty seeking behavior in rodents and men.  

PubMed

Recent discoveries indicate an important role for ghrelin in drug and alcohol reward and an ability of ghrelin to regulate mesolimbic dopamine activity. The role of dopamine in novelty seeking, and the association between this trait and drug and alcohol abuse, led us to hypothesize that ghrelin may influence novelty seeking behavior. To test this possibility we applied several complementary rodent models of novelty seeking behavior, i.e. inescapable novelty-induced locomotor activity (NILA), novelty-induced place preference and novel object exploration, in rats subjected to acute ghrelin receptor (growth hormone secretagogue receptor; GHSR) stimulation or blockade. Furthermore we assessed the possible association between polymorphisms in the genes encoding ghrelin and GHSR and novelty seeking behavior in humans. The rodent studies indicate an important role for ghrelin in a wide range of novelty seeking behaviors. Ghrelin-injected rats exhibited a higher preference for a novel environment and increased novel object exploration. Conversely, those with GHSR blockade drastically reduced their preference for a novel environment and displayed decreased NILA. Importantly, the mesolimbic ventral tegmental area selective GHSR blockade was sufficient to reduce the NILA response indicating that the mesolimbic GHSRs might play an important role in the observed novelty responses. Moreover, in untreated animals, a striking positive correlation between NILA and sucrose reward behavior was detected. Two GHSR single nucleotide polymorphisms (SNPs), rs2948694 and rs495225, were significantly associated with the personality trait novelty seeking, as assessed using the Temperament and Character Inventory (TCI), in human subjects. This study provides the first evidence for a role of ghrelin in novelty seeking behavior in animals and humans, and also points to an association between food reward and novelty seeking in rodents. PMID:23227170

Hansson, Caroline; Shirazi, Rozita H; Näslund, Jakob; Vogel, Heike; Neuber, Corinna; Holm, Göran; Anckarsäter, Henrik; Dickson, Suzanne L; Eriksson, Elias; Skibicka, Karolina P

2012-01-01

268

Unintentional wildlife poisoning and proposals for sustainable management of rodents.  

PubMed

In Europe, bromadiolone, an anticoagulant rodenticide authorized for plant protection, may be applied intensively in fields to control rodents. The high level of poisoning of wildlife that follows such treatments over large areas has been frequently reported. In France, bromadiolone has been used to control water voles (Arvicola terrestris) since the 1980s. Both regulation and practices of rodent control have evolved during the last 15 years to restrict the quantity of poisoned bait used by farmers. This has led to a drastic reduction of the number of cases of poisoned wildlife reported by the French surveillance network SAGIR. During the autumn and winter 2011, favorable weather conditions and high vole densities led to the staging of several hundreds of Red Kites (Milvus milvus) in the Puy-de-Dôme department (central France). At the same time, intensive treatments with bromadiolone were performed in this area. Although no misuse has been mentioned by the authorities following controls, 28 Red Kites and 16 Common Buzzards (Buteo buteo) were found dead during surveys in November and December 2011. For all these birds, poisoning by bromadiolone as the main cause of death was either confirmed or highly suspected. Other observations suggest a possible impact of bromadiolone on the breeding population of Red Kites in this area during the spring 2011. French regulation of vole control for plant protection is currently under revision, and we believe this event calls for more sustainable management of rodent outbreaks. Based on large-scale experiments undertaken in eastern France, we propose that direct control of voles at low density (with trapping or limited chemical treatments) and mechanical destruction of vole tunnels, mole control, landscape management, and predator fostering be included in future regulation because such practices could help resolve conservation and agricultural issues. PMID:24405288

Coeurdassier, Michael; Riols, Romain; Decors, Anouk; Mionnet, Aymeric; David, Fabienne; Quintaine, Thomas; Truchetet, Denis; Scheifler, Renaud; Giraudoux, Patrick

2014-04-01

269

Algorithmically generated rodent hepatic vascular trees in arbitrary detail.  

PubMed

Physiologically realistic geometric models of the vasculature in the liver are indispensable for modelling hepatic blood flow, the main connection between the liver and the organism. Current in vivo imaging techniques do not provide sufficiently detailed vascular trees for many simulation applications, so it is necessary to use algorithmic refinement methods. The method of Constrained Constructive Optimization (CCO) (Schreiner et al., 2006) is well suited for this purpose. Its results after calibration have been previously compared to experimentally acquired human vascular trees (Schwen and Preusser, 2012). The goal of this paper is to extend this calibration to the case of rodents (mice and rats), the most commonly used animal models in liver research. Based on in vivo and ex vivo micro-CT scans of rodent livers and their vasculature, we performed an analysis of various geometric features of the vascular trees. Starting from pruned versions of the original vascular trees, we applied the CCO procedure and compared these algorithmic results to the original vascular trees using a suitable similarity measure. The calibration of the postprocessing improved the algorithmic results compared to those obtained using standard CCO. In terms of angular features, the average similarity increased from 0.27 to 0.61, improving the total similarity from 0.28 to 0.40. Finally, we applied the calibrated algorithm to refine measured vascular trees to the (higher) level of detail desired for specific applications. Having successfully adapted the CCO algorithm to the rodent model organism, the resulting individual-specific refined hepatic vascular trees can now be used for advanced modeling involving, e.g., detailed blood flow simulations. PMID:25451523

Schwen, Lars Ole; Wei, Weiwei; Gremse, Felix; Ehling, Josef; Wang, Lei; Dahmen, Uta; Preusser, Tobias

2015-01-21

270

The Genetic Basis of Resistance to Anticoagulants in Rodents  

PubMed Central

Anticoagulant compounds, i.e., derivatives of either 4-hydroxycoumarin (e.g., warfarin, bromadiolone) or indane-1,3-dione (e.g., diphacinone, chlorophacinone), have been in worldwide use as rodenticides for >50 years. These compounds inhibit blood coagulation by repression of the vitamin K reductase reaction (VKOR). Anticoagulant-resistant rodent populations have been reported from many countries and pose a considerable problem for pest control. Resistance is transmitted as an autosomal dominant trait although, until recently, the basic genetic mutation was unknown. Here, we report on the identification of eight different mutations in the VKORC1 gene in resistant laboratory strains of brown rats and house mice and in wild-caught brown rats from various locations in Europe with five of these mutations affecting only two amino acids (Tyr139Cys, Tyr139Ser, Tyr139Phe and Leu128Gln, Leu128Ser). By recombinant expression of VKORC1 constructs in HEK293 cells we demonstrate that mutations at Tyr139 confer resistance to warfarin at variable degrees while the other mutations, in addition, dramatically reduce VKOR activity. Our data strongly argue for at least seven independent mutation events in brown rats and two in mice. They suggest that mutations in VKORC1 are the genetic basis of anticoagulant resistance in wild populations of rodents, although the mutations alone do not explain all aspects of resistance that have been reported. We hypothesize that these mutations, apart from generating structural changes in the VKORC1 protein, may induce compensatory mechanisms to maintain blood clotting. Our findings provide the basis for a DNA-based field monitoring of anticoagulant resistance in rodents. PMID:15879509

Pelz, Hans-Joachim; Rost, Simone; Hünerberg, Mirja; Fregin, Andreas; Heiberg, Ann-Charlotte; Baert, Kristof; MacNicoll, Alan D.; Prescott, Colin V.; Walker, Anne-Sophie; Oldenburg, Johannes; Müller, Clemens R.

2005-01-01

271

Tropical Prediction Center: National Hurricane Center  

NSDL National Science Digital Library

The National Hurricane Center contains news of active tropical systems; a hurricane awareness section about the hazards of hurricanes and what you can do to help protect yourself, your family, and your property; links to regional tropical cyclone centers; tropical weather outlooks, marine forecasts, and Sea Surface Temperature analyses; blank hurricane tracking charts; and current season summaries and tropical cyclone reports including synoptic history, meteorological statistics, casualties and damages, and the post-analysis best track.

272

Nonhuman gamblers: lessons from rodents, primates, and robots  

PubMed Central

The search for neuronal and psychological underpinnings of pathological gambling in humans would benefit from investigating related phenomena also outside of our species. In this paper, we present a survey of studies in three widely different populations of agents, namely rodents, non-human primates, and robots. Each of these populations offers valuable and complementary insights on the topic, as the literature demonstrates. In addition, we highlight the deep and complex connections between relevant results across these different areas of research (i.e., cognitive and computational neuroscience, neuroethology, cognitive primatology, neuropsychiatry, evolutionary robotics), to make the case for a greater degree of methodological integration in future studies on pathological gambling. PMID:24574984

Paglieri, Fabio; Addessi, Elsa; De Petrillo, Francesca; Laviola, Giovanni; Mirolli, Marco; Parisi, Domenico; Petrosino, Giancarlo; Ventricelli, Marialba; Zoratto, Francesca; Adriani, Walter

2014-01-01

273

Pulmonary Toxicity Studies of Lunar Dusts in Rodents  

NASA Technical Reports Server (NTRS)

NASA will build an outpost on the lunar surface for long-duration human habitation and research. The surface of the Moon is covered by a layer of fine, reactive dust, and the living quarters in the lunar outpost are expected to be contaminated by lunar dust. NASA established the Lunar Airborne Dust Toxicity Advisory Group (LADTAG) to evaluate the risk of exposure to the dust and to establish safe exposure limits for astronauts working in the lunar habitat. Because the toxicity of lunar dust is not known, LADTAG has recommended investigating its toxicity in the lungs of laboratory animals. After receiving this recommendation, NASA directed the JSC Toxicology Laboratory to determine the pulmonary toxicity of lunar dust in exposed rodents. The rodent pulmonary toxicity studies proposed here are the same as those proposed by the LADTAG. Studies of the pulmonary toxicity of a dust are generally done first in rodents by intratracheal instillation (ITI). This toxicity screening test is then followed by an inhalation study, which requires much more of the test dust and is labor intensive. We succeeded in completing an ITI study on JSC-1 lunar dust simulant in mice (Lam et al., Inhalation Toxicology 14:901-916, 2002, and Inhalation Toxicology 14: 917-928, 2002), and have conducted a pilot ITI study to examine the acute toxicity of an Apollo lunar (highland) dust sample. Preliminary results obtained by examining lung lavage fluid from dust-treated mice show that lunar dust was somewhat toxic (more toxic than TiO2, but less than quartz dust). More extensive studies have been planned to further examine lung lavage fluid for biomarkers of toxicity and lung tissues for histopathological lesions in rodents exposed to aged and activated lunar dust samples. In these studies, reference dusts (TiO2 and quartz) of known toxicities and have industrial exposure limits will be studied in parallel so the relative toxicity of lunar dust can be determined. The ITI results will also be useful for choosing an exposure concentration for the animal inhalation study on a selected lunar dust sample, which is included as a part of this proposal. The animal inhalation exposure will be conducted with lunar dust simulant prior to the study with the lunar dust. The simulant exposure will ensure that the study techniques used with actual lunar dust will be successful. The results of ITI and inhalation studies will reveal the toxicological risk of exposures and are essential for setting exposure limits on lunar dust for astronauts living in the lunar habitat.

Lam, Chiu-wing; James, John T.; Taylor, Larry

2008-01-01

274

Hemorrhagic gastritis in free-living rodents in Idaho.  

PubMed

Between February 1992 and March 1994, four species of rodent from the Snake River Birds of Prey Area near Boise, Idaho (USA) were necropsied. Hemorrhagic gastritis was observed in 16 of 131 Townsend's ground squirrels (Spermophilus townsendii), one of 11 Ord's kangaroo rats (Dipodomys ordii) and the one Great Basin pocket mouse (Perognathus parvus) evaluated. No lesions were observed in 14 white-footed deer mice (Peromyscus maniculatus). Tissue from one Townsend's ground squirrel was negative for Helicobacter sp.-like bacteria. PMID:9359067

Wilber, P G; Duszynski, D W; Van Horne, B

1996-10-01

275

A protocol for a lung neovascularization model in rodents  

PubMed Central

By providing insight into the cellular events of vascular injury and repair, experimental model systems seek to promote timely therapeutic strategies for human disease. The goal of many current studies of neovascularization is to identify cells critical to the process and their role in vascular channel assembly. We propose here a protocol to analyze, in an in vivo rodent model, vessel and capillary remodeling (reorganization and growth) in the injured lung. Sequential analyses of stages in the assembly of vascular structures, and of relevant cell types, provide further opportunities to study the molecular and cellular determinants of lung neovascularization. PMID:18323809

Jones, Rosemary C; Capen, Diane E; Petersen, Bodil; Jain, Rakesh K; Duda, Dan G

2009-01-01

276

Rodent Models and Behavioral Outcomes of Cervical Spinal Cord Injury  

PubMed Central

Rodent spinal cord injury (SCI) models have been developed to examine functional and physiological deficits after spinal cord injury with the hope that these models will elucidate information about human SCI. Models are needed to examine possible treatments and to understand histopathology after SCI; however, they should be considered carefully and chosen based on the goals of the study being performed. Contusion, compression, transection, and other models exist and have the potential to reveal important information about SCI that may be related to human SCI and the outcomes of treatment and timing of intervention. PMID:25309824

Geissler, Sydney A.; Schmidt, Christine E.; Schallert, Timothy

2014-01-01

277

Introduction to Tropical Geometry Diane Maclagan  

E-print Network

140 Chapter 4. Tropical Rain Forest 145 §4.1. Hyperplane Arrangements 145 §4.2. Matroids 153 §4Introduction to Tropical Geometry Diane Maclagan Bernd Sturmfels Mathematics Institute, University;2010 Mathematics Subject Classification. Primary 14T05 Abstract. Tropical geometry is a combinatorial shadow

Maclagan, Diane

278

Introduction to Tropical Geometry Diane Maclagan  

E-print Network

Intersection 126 §3.7. Exercises 139 Chapter 4. Tropical Rain Forest 143 §4.1. Hyperplane Arrangements 143 §4Introduction to Tropical Geometry Diane Maclagan Bernd Sturmfels Mathematics Institute, University;1991 Mathematics Subject Classification. Primary 14T05 Abstract. Tropical geometry is a combinatorial shadow

Maclagan, Diane

279

Introduction to Tropical Geometry Diane Maclagan  

E-print Network

Intersection 134 §3.7. Exercises 149 Chapter 4. Tropical Rain Forest 153 §4.1. Hyperplane Arrangements 153 §4Introduction to Tropical Geometry Diane Maclagan Bernd Sturmfels Mathematics Institute, University. Tropical geometry is a combinatorial shadow of algebraic geometry, offering new polyhedral tools to compute

Maclagan, Diane

280

Self-organized criticality in tropical convection?  

E-print Network

Self-organized criticality in tropical convection? Bob Plant Climate Thermodynamics Workshop 22nd picture of tropical convection What is self-organized criticality? Evidence for SOC in convection 1st attempt at SOC model of convection No conclusions, just open questions SOC in tropical convection? ­ p.1

Plant, Robert

281

Tropical rainforest canopies and climate change  

Microsoft Academic Search

There is less certainty about the impact of climate change on tropical rainforests than on temperate forests because of the comparative lack of background data and because few large scale experiments have been, and are being, carried out in tropical rainforests. Many of the factors critical to the future of tropical rainforests concern canopies, the key processes that take place

NIGEL E. STORK; J. BALSTON; G. D. FARQUHAR; P. J. FRANKS; J. A. M. HOLTUM; M. J. LIDDELL

2007-01-01

282

Rodent ultrasonic vocalizations are bound to active sniffing behavior  

PubMed Central

During rodent active behavior, multiple orofacial sensorimotor behaviors, including sniffing and whisking, display rhythmicity in the theta range (~5–10 Hz). During specific behaviors, these rhythmic patterns interlock, such that execution of individual motor programs becomes dependent on the state of the others. Here we performed simultaneous recordings of the respiratory cycle and ultrasonic vocalization emission by adult rats and mice in social settings. We used automated analysis to examine the relationship between breathing patterns and vocalization over long time periods. Rat ultrasonic vocalizations (USVs, “50 kHz”) were emitted within stretches of active sniffing (5–10 Hz) and were largely absent during periods of passive breathing (1–4 Hz). Because ultrasound was tightly linked to the exhalation phase, the sniffing cycle segmented vocal production into discrete calls and imposed its theta rhythmicity on their timing. In turn, calls briefly prolonged exhalations, causing an immediate drop in sniffing rate. Similar results were obtained in mice. Our results show that ultrasonic vocalizations are an integral part of the rhythmic orofacial behavioral ensemble. This complex behavioral program is thus involved not only in active sensing but also in the temporal structuring of social communication signals. Many other social signals of mammals, including monkey calls and human speech, show structure in the theta range. Our work points to a mechanism for such structuring in rodent ultrasonic vocalizations. PMID:25477796

Sirotin, Yevgeniy B.; Costa, Martín Elias; Laplagne, Diego A.

2014-01-01

283

Suppression of replicative senescence by rapamycin in rodent embryonic cells.  

PubMed

The TOR (target of rapamycin) pathway is involved in aging in diverse organisms from yeast to mammals. We have previously demonstrated in human and rodent cells that mTOR converts stress-induced cell cycle arrest to irreversible senescence (geroconversion), whereas rapamycin decelerates or suppresses geroconversion during cell cycle arrest. Here, we investigated whether rapamycin can suppress replicative senescence of rodent cells. Mouse embryonic fibroblasts (MEFs) gradually acquired senescent morphology and ceased proliferation. Rapamycin decreased cellular hypertrophy, and SA-?-Gal staining otherwise developed by 4-6 passages, but it blocked cell proliferation, masking its effects on replicative lifespan. We determined that rapamycin inhibited pS6 at 100-300 pM and inhibited proliferation with IC(50) around 30 pM. At 30 pM, rapamycin partially suppressed senescence. However, the gerosuppressive effect was balanced by the cytostatic effect, making it difficult to suppress senescence without causing quiescence. We also investigated rat embryonic fibroblasts (REFs), which exhibited markers of senescence at passage 7, yet were able to slowly proliferate until 12-14 passages. REFs grew in size, acquired a large, flat cell morphology, SA-?-Gal staining and components of DNA damage response (DDR), in particular, ?H2AX/53BP1 foci. Incubation of REFs with rapamycin (from passage 7 to passage 10) allowed REFs to overcome the replicative senescence crisis. Following rapamycin treatment and removal, a fraction of proliferating REFs gradually increased and senescent phenotype disappeared completely by passage 24. PMID:22672902

Pospelova, Tatiana V; Leontieva, Olga V; Bykova, Tatiana V; Zubova, Svetlana G; Pospelov, Valery A; Blagosklonny, Mikhail V

2012-06-15

284

Variations in Rodent Models of Type 1 Diabetes: Islet Morphology  

PubMed Central

Type 1 diabetes (T1D) is characterized by hyperglycemia due to lost or damaged islet insulin-producing ?-cells. Rodent models of T1D result in hyperglycemia, but with different forms of islet deterioration. This study focused on 1 toxin-induced and 2 autoimmune rodent models of T1D: BioBreeding Diabetes Resistant rats, nonobese diabetic mice, and Dark Agouti rats treated with streptozotocin. Immunochemistry was used to evaluate the insulin levels in the ?-cells, cell composition, and insulitis. T1D caused complete or significant loss of ?-cells in all animal models, while increasing numbers of ?-cells. Lymphocytic infiltration was noted in and around islets early in the progression of autoimmune diabetes. The loss of lymphocytic infiltration coincided with the absence of ?-cells. In all models, the remaining ?- and ?-cells regrouped by relocating to the islet center. The resulting islets were smaller in size and irregularly shaped. Insulin injections subsequent to induction of toxin-induced diabetes significantly preserved ?-cells and islet morphology. Diabetes in animal models is anatomically heterogeneous and involves important changes in numbers and location of the remaining ?- and ?-cells. Comparisons with human pancreatic sections from healthy and diabetic donors showed similar morphological changes to the diabetic BBDR rat model. PMID:23762878

Novikova, Lesya; Smirnova, Irina V.; Dotson, Abby L.; Benedict, Stephen H.

2013-01-01

285

New Insights from Rodent Models of Fatty Liver Disease  

PubMed Central

Abstract Rodent models of fatty liver disease are essential research tools that provide a window into disease pathogenesis and a testing ground for prevention and treatment. Models come in many varieties involving dietary and genetic manipulations, and sometimes both. High-energy diets that induce obesity do not uniformly cause fatty liver disease; this has prompted close scrutiny of specific macronutrients and nutrient combinations to determine which have the greatest potential for hepatotoxicity. At the same time, diets that do not cause obesity or the metabolic syndrome but do cause severe steatohepatitis have been exploited to study factors important to progressive liver injury, including cell death, oxidative stress, and immune activation. Rodents with a genetic predisposition to overeating offer yet another model in which to explore the evolution of fatty liver disease. In some animals that overeat, steatohepatitis can develop even without resorting to a high-energy diet. Importantly, these models and others have been used to document that aerobic exercise can prevent or reduce fatty liver disease. This review focuses primarily on lessons learned about steatohepatitis from manipulations of diet and eating behavior. Numerous additional insights about hepatic lipid metabolism, which have been gained from genetically engineered mice, are also mentioned. Antioxid. Redox Signal. 15, 535–550. PMID:21126212

2011-01-01

286

Rodent models of chemotherapy-induced peripheral neuropathy.  

PubMed

Peripheral neuropathy is a common and dose-limiting side effect of many chemotherapeutic drugs. These include platinum compounds, taxanes, vinca alkaloids, proteasome inhibitors, and others such as thalidomide and suramin. Although many rodent models have been developed using either mice or rats, there is limited consistency in the dose or mode of delivery of the drug; the sex, age, and genetic background of the animal used in the study; and the outcome measures used in evaluation of the peripheral neuropathy. Behavioral assays are commonly used to evaluate evoked sensory responses but are unlikely to be a good representation of the spontaneous sensory paresthesias that the patients experience. Electrophysiologic tests evaluate the integrity of large myelinated populations and are useful in drugs that cause either demyelination or degeneration of large myelinated axons but are insensitive to degeneration of unmyelinated axons in early stages of neuropathy. Histopathologic tools offer an unbiased way to evaluate the degree of axonal degeneration or changes in neuronal cell body but are often time consuming and require processing of the tissue after the study is completed. Nevertheless, use of drug doses and mode of delivery that are relevant to the clinical protocols and use of outcome measures that are both sensitive and objective in evaluation of the length-dependent distal axonal degeneration seen in most chemotherapy-induced peripheral neuropathies may improve the translational utility of these rodent models. PMID:24615440

Höke, Ahmet; Ray, Mitali

2014-01-01

287

Molecular detection of bacterial contamination in gnotobiotic rodent units  

PubMed Central

Gnotobiotic rodents provide an important technique to study the functional roles of commensal bacteria in host physiology and pathophysiology. To ensure sterility, these animals must be screened frequently for contamination. The traditional screening approaches of culturing and Gram staining feces have inherent limitations, as many bacteria are uncultivable and fecal Gram stains are difficult to interpret. Thus, we developed and validated molecular methods to definitively detect and identify contamination in germ-free (GF) and selectively colonized animals. Fresh fecal pellets were collected from rodents housed in GF isolators, spontaneously contaminated ex-GF isolators, selectively colonized isolators and specific pathogen-free (SPF) conditions. DNA isolated from mouse and rat fecal samples was amplified by polymerase chain reaction (PCR) and subjected to quantitative PCR (qPCR) using universal primers that amplify the 16S rRNA gene from all bacterial groups. PCR products were sequenced to identify contaminating bacterial species. Random amplification of polymorphic DNA (RAPD) PCR profiles verified bacterial inoculation of selectively colonized animals. These PCR techniques more accurately detected and identified GF isolator contamination than current standard approaches. These molecular techniques can be utilized to more definitively screen GF and selectively colonized animals for bacterial contamination when Gram stain and/or culture results are un-interpretable or inconsistent. PMID:23887190

Packey, Christopher D; Shanahan, Michael T; Manick, Sayeed; Bower, Maureen A; Ellermann, Melissa; Tonkonogy, Susan L; Carroll, Ian M; Sartor, R Balfour

2013-01-01

288

Studying autism in rodent models: reconciling endophenotypes with comorbidities.  

PubMed

Autism spectrum disorder (ASD) patients commonly exhibit a variety of comorbid traits including seizures, anxiety, aggressive behavior, gastrointestinal problems, motor deficits, abnormal sensory processing, and sleep disturbances for which the cause is unknown. These features impact negatively on daily life and can exaggerate the effects of the core diagnostic traits (social communication deficits and repetitive behaviors). Studying endophenotypes relevant to both core and comorbid features of ASD in rodent models can provide insight into biological mechanisms underlying these disorders. Here we review the characterization of endophenotypes in a selection of environmental, genetic, and behavioral rodent models of ASD. In addition to exhibiting core ASD-like behaviors, each of these animal models display one or more endophenotypes relevant to comorbid features including altered sensory processing, seizure susceptibility, anxiety-like behavior, and disturbed motor functions, suggesting that these traits are indicators of altered biological pathways in ASD. However, the study of behaviors paralleling comorbid traits in animal models of ASD is an emerging field and further research is needed to assess altered gastrointestinal function, aggression, and disorders of sleep onset across models. Future studies should include investigation of these endophenotypes in order to advance our understanding of the etiology of this complex disorder. PMID:23898259

Argyropoulos, Andrew; Gilby, Krista L; Hill-Yardin, Elisa L

2013-01-01

289

Studying Autism in Rodent Models: Reconciling Endophenotypes with Comorbidities  

PubMed Central

Autism spectrum disorder (ASD) patients commonly exhibit a variety of comorbid traits including seizures, anxiety, aggressive behavior, gastrointestinal problems, motor deficits, abnormal sensory processing, and sleep disturbances for which the cause is unknown. These features impact negatively on daily life and can exaggerate the effects of the core diagnostic traits (social communication deficits and repetitive behaviors). Studying endophenotypes relevant to both core and comorbid features of ASD in rodent models can provide insight into biological mechanisms underlying these disorders. Here we review the characterization of endophenotypes in a selection of environmental, genetic, and behavioral rodent models of ASD. In addition to exhibiting core ASD-like behaviors, each of these animal models display one or more endophenotypes relevant to comorbid features including altered sensory processing, seizure susceptibility, anxiety-like behavior, and disturbed motor functions, suggesting that these traits are indicators of altered biological pathways in ASD. However, the study of behaviors paralleling comorbid traits in animal models of ASD is an emerging field and further research is needed to assess altered gastrointestinal function, aggression, and disorders of sleep onset across models. Future studies should include investigation of these endophenotypes in order to advance our understanding of the etiology of this complex disorder. PMID:23898259

Argyropoulos, Andrew; Gilby, Krista L.; Hill-Yardin, Elisa L.

2013-01-01

290

Causal evidence between monsoon and evolution of rhizomyine rodents  

NASA Astrophysics Data System (ADS)

The modern Asian monsoonal systems are currently believed to have originated around the end of the Oligocene following a crucial step of uplift of the Tibetan-Himalayan highlands. Although monsoon possibly drove the evolution of many mammal lineages during the Neogene, no evidence thereof has been provided so far. We examined the evolutionary history of a clade of rodents, the Rhizomyinae, in conjunction with our current knowledge of monsoon fluctuations over time. The macroevolutionary dynamics of rhizomyines were analyzed within a well-constrained phylogenetic framework coupled with biogeographic and evolutionary rate studies. The evolutionary novelties developed by these rodents were surveyed in parallel with the fluctuations of the Indian monsoon so as to evaluate synchroneity and postulate causal relationships. We showed the existence of three drops in biodiversity during the evolution of rhizomyines, all of which reflected elevated extinction rates. Our results demonstrated linkage of monsoon variations with the evolution and biogeography of rhizomyines. Paradoxically, the evolution of rhizomyines was accelerated during the phases of weakening of the monsoons, not of strengthening, most probably because at those intervals forest habitats declined, which triggered extinction and progressive specialization toward a burrowing existence.

López-Antoñanzas, Raquel; Knoll, Fabien; Wan, Shiming; Flynn, Lawrence J.

2015-03-01

291

Management of Rodent Exposure and Allergy in the Pediatric Population  

PubMed Central

Although rodent allergy has long been recognized as an occupational disease, it has only been in the past decade that it has been recognized as a community-based disease that affects children. Most homes in the US have detectable mouse allergen, but the concentrations in inner-city homes are orders of magnitude higher than those found in suburban homes. Home mouse allergen exposure has been linked to sensitization to mouse, and children with asthma who are both sensitized and exposed to high mouse allergen concentrations at home are at greater risk for symptoms, exacerbations and reduced lung function. Rat allergen is found primarily in inner-city homes and has also been linked to asthma morbidity among sensitized children. The objective of this review is to summarize the scientific literature on rodents and their allergens, the effects of exposure to these allergens on allergic respiratory disease, and to make recommendations, based on this evidence base, for the evaluation and management of mouse allergy in the pediatric population. PMID:23912589

Matsui, Elizabeth C.

2013-01-01

292

Holocene Vegetation History from Fossil Rodent Middens near Arequipa, Peru  

NASA Astrophysics Data System (ADS)

Rodent (Abrocoma, Lagidium, Phyllotis) middens collected from 2350 to 2750 m elevation near Arequipa, Peru (16°S), provide an ?9600-yr vegetation history of the northern Atacama Desert, based on identification of >50 species of plant macrofossils. These midden floras show considerable stability throughout the Holocene, with slightly more mesophytic plant assemblages in the middle Holocene. Unlike the southwestern United States, rodent middens of mid-Holocene age are common. In the Arequipa area, the midden record does not reflect any effects of a mid-Holocene mega drought proposed from the extreme lowstand (100 m below modern levels, >6000 to 3500 yr B.P.) of Lake Titicaca, only 200 km east of Arequipa. This is perhaps not surprising, given other evidence for wetter summers on the Pacific slope of the Andes during the middle Holocene as well as the poor correlation of summer rainfall among modern weather stations in the central Andes-Atacama Desert. The apparent difference in paleoclimatic reconstructions suggests that it is premature to relate changes observed during the Holocene to changes in El Niño Southern Oscillation modes.

Holmgren, Camille A.; Betancourt, Julio L.; Rylander, Kate Aasen; Roque, Jose; Tovar, Oscar; Zeballos, Horacio; Linares, Eliana; Quade, Jay

2001-09-01

293

Emmonsiosis of wild rodents and insectivores in Czechland.  

PubMed

Adiaspores of the fungus Emmonsia crescens were detected microscopically in the lung tissue of 13% of 10.081 small mammals belonging to 24 species examined in 14 areas of the Czech Republic between 1986 and 1997; 441/1.934 (23%) Clethrionomys glareolus, 1/6 (17%) Arvicola terrestris, 357/2.172 (16%) Apodemus flavicollis, 220/1.981 (11%). A sylvaticus, 23/265 (9%) A. microps, 11/81 (14%) Microtus subterraneus, 93/1.275 (7%) M. arvalis, 98/1.439 (7%) M. agrestis, 1/3 (33%) Ondatra zibethicus, 1/1 Cricetus cricetus, 1/20 (5%) Crocidura suaveolens, 2/40 (5%) Neomys fodiens, and 13/529 (2%) Sorex araneus were infected. Emmonsiosis was not recorded among the species of rodents that do not build their nests in the soil (Muscardinus avellanarius, Micromys minutus, Mus musculus, Rattus norvegicus). The overall prevalence of emmonsiosis was significantly higher in adult (19%) than in juvenile (7%) mammals, and in rodents (13%, and 20% in adults) than in insectivores (2%, and 4% in adults). The frequency of infected mammals also varied according to geographic area, altitude, habitat, and season. PMID:10231750

Hubálek, Z

1999-04-01

294

The need for speed in rodent locomotion analyses.  

PubMed

Locomotion analysis is now widely used across many animal species to understand the motor defects in disease, functional recovery following neural injury, and the effectiveness of various treatments. More recently, rodent locomotion analysis has become an increasingly popular method in a diverse range of research. Speed is an inseparable aspect of locomotion that is still not fully understood, and its effects are often not properly incorporated while analyzing data. In this hybrid manuscript, we accomplish three things: (1) review the interaction between speed and locomotion variables in rodent studies, (2) comprehensively analyze the relationship between speed and 162 locomotion variables in a group of 16 wild-type mice using the CatWalk gait analysis system, and (3) develop and test a statistical method in which locomotion variables are analyzed and reported in the context of speed. Notable results include the following: (1) over 90% of variables, reported by CatWalk, were dependent on speed with an average R(2) value of 0.624, (2) most variables were related to speed in a nonlinear manner, (3) current methods of controlling for speed are insufficient, and (4) the linear mixed model is an appropriate and effective statistical method for locomotion analyses that is inclusive of speed-dependent relationships. Given the pervasive dependency of locomotion variables on speed, we maintain that valid conclusions from locomotion analyses cannot be made unless they are analyzed and reported within the context of speed. PMID:24890845

Batka, Richard J; Brown, Todd J; Mcmillan, Kathryn P; Meadows, Rena M; Jones, Kathryn J; Haulcomb, Melissa M

2014-10-01

295

Genome Diversification Mechanism of Rodent and Lagomorpha Chemokine Genes  

PubMed Central

Chemokines are a large family of small cytokines that are involved in host defence and body homeostasis through recruitment of cells expressing their receptors. Their genes are known to undergo rapid evolution. Therefore, the number and content of chemokine genes can be quite diverse among the different species, making the orthologous relationships often ambiguous even between closely related species. Given that rodents and rabbit are useful experimental models in medicine and drug development, we have deduced the chemokine genes from the genome sequences of several rodent species and rabbit and compared them with those of human and mouse to determine the orthologous relationships. The interspecies differences should be taken into consideration when experimental results from animal models are extrapolated into humans. The chemokine gene lists and their orthologous relationships presented here will be useful for studies using these animal models. Our analysis also enables us to reconstruct possible gene duplication processes that generated the different sets of chemokine genes in these species. PMID:23991422

Shibata, Kanako; Yoshie, Osamu; Tanase, Sumio

2013-01-01

296

Rodent ectoparasites from two locations in northwestern Florida.  

PubMed

From Feb.-Apr. 1999, 19 species of ectoparasitic arthropods (2 sucking lice, 4 fleas, 4 ticks, 2 mesostigmatid mites, 5 chiggers, 2 fur mites) were recovered from 106 rodents belonging to 5 species (cotton mouse, Peromyscus gossypinus, n = 64; cotton rat, Sigmodon hispidus, n = 23; eastern woodrat, Neotoma floridana, n = 9; golden mouse, Ochrotomys nuttalli, n = 9; eastern gray squirrel, Sciurus carolinensis, n = 1) at Tall Timbers Research Station, Leon County, Florida. During the same period, 13 species of ectoparasites (2 sucking lice, 1 flea, 3 ticks, 3 mesostigmatid mites, 2 chiggers, 2 fur mites) were recovered from 57 rodents belonging to 3 species (S. hispidus, n = 40; black rat, Rattus rattus, n = 16; S. carolinensis, n = 1) from Panama City, Bay County, Florida. Noteworthy ectoparasite records include Ixodes minor from both sites, which extends the known geographical range of this tick, and Stenoponia americana from Tall Timbers that represents the second documented Florida record of this flea. Potential tick vectors (Dermacentor variabilis and Ixodes scapularis) of zoonotic pathogens (Rickettsia rickettsii and Borrelia burgdorferi) were collected at both sites. On S. hispidus, fleas were more prevalent at Tall Timbers but sucking lice, chiggers, ticks, mesostigmatid and listrophorid mites all were more prevalent at the Panama City site. Arthropods recovered from arboreal nests (n = 3) of O. nuttalli at Tall Timbers included 3 species of ectoparasites (1 tick, 2 laelapid mites). PMID:11217221

Durden, L A; Hu, R; Oliver, J H; Cilek, J E

2000-12-01

297

Functional Evolution of the Feeding System in Rodents  

PubMed Central

The masticatory musculature of rodents has evolved to enable both gnawing at the incisors and chewing at the molars. In particular, the masseter muscle is highly specialised, having extended anteriorly to originate from the rostrum. All living rodents have achieved this masseteric expansion in one of three ways, known as the sciuromorph, hystricomorph and myomorph conditions. Here, we used finite element analysis (FEA) to investigate the biomechanical implications of these three morphologies, in a squirrel, guinea pig and rat. In particular, we wished to determine whether each of the three morphologies is better adapted for either gnawing or chewing. Results show that squirrels are more efficient at muscle-bite force transmission during incisor gnawing than guinea pigs, and that guinea pigs are more efficient at molar chewing than squirrels. This matches the known diet of nuts and seeds that squirrels gnaw, and of grasses that guinea pigs grind down with their molars. Surprisingly, results also indicate that rats are more efficient as well as more versatile feeders than both the squirrel and guinea pig. There seems to be no compromise in biting efficiency to accommodate the wider range of foodstuffs and the more general feeding behaviour adopted by rats. Our results show that the morphology of the skull and masticatory muscles have allowed squirrels to specialise as gnawers and guinea pigs as chewers, but that rats are high-performance generalists, which helps explain their overwhelming success as a group. PMID:22558427

Cox, Philip G.; Rayfield, Emily J.; Fagan, Michael J.; Herrel, Anthony; Pataky, Todd C.; Jeffery, Nathan

2012-01-01

298

Causal evidence between monsoon and evolution of rhizomyine rodents  

PubMed Central

The modern Asian monsoonal systems are currently believed to have originated around the end of the Oligocene following a crucial step of uplift of the Tibetan-Himalayan highlands. Although monsoon possibly drove the evolution of many mammal lineages during the Neogene, no evidence thereof has been provided so far. We examined the evolutionary history of a clade of rodents, the Rhizomyinae, in conjunction with our current knowledge of monsoon fluctuations over time. The macroevolutionary dynamics of rhizomyines were analyzed within a well-constrained phylogenetic framework coupled with biogeographic and evolutionary rate studies. The evolutionary novelties developed by these rodents were surveyed in parallel with the fluctuations of the Indian monsoon so as to evaluate synchroneity and postulate causal relationships. We showed the existence of three drops in biodiversity during the evolution of rhizomyines, all of which reflected elevated extinction rates. Our results demonstrated linkage of monsoon variations with the evolution and biogeography of rhizomyines. Paradoxically, the evolution of rhizomyines was accelerated during the phases of weakening of the monsoons, not of strengthening, most probably because at those intervals forest habitats declined, which triggered extinction and progressive specialization toward a burrowing existence. PMID:25759260

López-Antoñanzas, Raquel; Knoll, Fabien; Wan, Shiming; Flynn, Lawrence J.

2015-01-01

299

Chromosomal instability in rodents caused by pollution from Baikonur cosmodrome.  

PubMed

An assessment of the health status of ecosystems exposed to man-made pollution is a vital issue for many countries. Particularly it concerns the consequences of contamination caused by the activity of the space industry. Each rocket launch is accompanied by the introduction of parts of the rocket propellant into the environment. This study aims to scrutinize the effect of the components of rocket fuel on the induction of lipid peroxidation and chromosomal aberrations on rodents inhabiting the area exposed to pollution from Baikonur cosmodrome. The results showed the increase of the level of lipid hydroperoxide and malondialdehyde in the livers of Citellus pygmaeus Pallas and Mus musculus L., which indicates an augmentation of free radical activity and DNA damage. The cytogenetic analysis of bone marrow cells revealed that the frequency of chromosomal aberrations was a few times higher in the rodents from contaminated territory. The signs of oxidative stress and high level of chromosomal aberrations indicate the environmental impact of the cosmodrome, and its possible toxic and mutagenic effects on ecosystems. PMID:24990120

Kolumbayeva, Saule; Begimbetova, Dinara; Shalakhmetova, Tamara; Saliev, Timur; Lovinskaya, Anna; Zhunusbekova, Benazir

2014-09-01

300

Causal evidence between monsoon and evolution of rhizomyine rodents.  

PubMed

The modern Asian monsoonal systems are currently believed to have originated around the end of the Oligocene following a crucial step of uplift of the Tibetan-Himalayan highlands. Although monsoon possibly drove the evolution of many mammal lineages during the Neogene, no evidence thereof has been provided so far. We examined the evolutionary history of a clade of rodents, the Rhizomyinae, in conjunction with our current knowledge of monsoon fluctuations over time. The macroevolutionary dynamics of rhizomyines were analyzed within a well-constrained phylogenetic framework coupled with biogeographic and evolutionary rate studies. The evolutionary novelties developed by these rodents were surveyed in parallel with the fluctuations of the Indian monsoon so as to evaluate synchroneity and postulate causal relationships. We showed the existence of three drops in biodiversity during the evolution of rhizomyines, all of which reflected elevated extinction rates. Our results demonstrated linkage of monsoon variations with the evolution and biogeography of rhizomyines. Paradoxically, the evolution of rhizomyines was accelerated during the phases of weakening of the monsoons, not of strengthening, most probably because at those intervals forest habitats declined, which triggered extinction and progressive specialization toward a burrowing existence. PMID:25759260

López-Antoñanzas, Raquel; Knoll, Fabien; Wan, Shiming; Flynn, Lawrence J

2015-01-01

301

Population ecology of hantavirus rodent hosts in southern Brazil.  

PubMed

In this study we analyze population dynamics of hantavirus rodent hosts and prevalence of infection over a 2-year period in Southern Brazil, a region with a high incidence of hantavirus pulmonary syndrome. The 14 small mammal species captured were composed of 10 rodents and four marsupials, the six most abundant species being Akodon serrensis, Oxymycterus judex, Akodon montensis, Akodon paranaensis, Oligoryzomys nigripes, and Thaptomys nigrita. These species displayed a similar pattern with increasing population sizes in fall/winter caused by recruitment and both, increase in reproductive activity and higher hantavirus prevalence in spring/summer. Specific associations between A. montensis/Jaborá Virus (JABV) and O. nigripes/Juquitiba-like Virus (JUQV-like) and spillover infections between A. paranaensis/JABV, A. serrensis/JABV, and A. paranaensis/JUQV-like were observed. Spillover infection in secondary hosts seems to play an important role in maintaining JABV and JUQV-like in the hantavirus sylvatic cycle mainly during periods of low prevalence in primary hosts. PMID:24935954

Teixeira, Bernardo R; Loureiro, Nathalie; Strecht, Liana; Gentile, Rosana; Oliveira, Renata C; Guterres, Alexandro; Fernandes, Jorlan; Mattos, Luciana H B V; Raboni, Sonia M; Rubio, Giselia; Bonvicino, Cibele R; dos Santos, Claudia N Duarte; Lemos, Elba R S; D'Andrea, Paulo S

2014-08-01

302

Tropical Depression Kyle, October 10, 2002  

NSDL National Science Digital Library

Tropical Depression Kyle is expected to reach the northeast Florida coast in 24 hours. It is currently packing sustained winds of 30 mph. The storm developed on September 20, 2002 and has been classified as a sub-tropical depression, tropical storm, hurricane, tropical storm, and now a tropical depression. The visualization zooms down to the storm and then shows the overall rain structure of Kyle. Yellow represents areas where at least 0.5 inches of rain fell per hour. Green shows at least 1.0 inch of rain, and red depicts more than 2.0 inches of rain per hour.

Lori Perkins

2002-10-10

303

Tropical sprue after travel to Tanzania.  

PubMed

Tropical sprue (TS) is a diagnosis to consider in travelers with prolonged diarrhea and a malabsorption syndrome after return from tropical countries, particularly India and Southeast Asia. TS is an unusual condition in tropical Africa. Textbooks of tropical medicine indicate a low endemicity in Nigeria and a limited number of cases in South Africa and Zimbabwe. A Medline search from 1979 to mid 1998 using "Tanzania and tropical sprue" as key words disclosed no hits. We report herein a case of TS in a European traveler, who lived in Tanzania for 8 months. PMID:10689238

Peetermans, W E; Vonck, A

2000-01-01

304

Tropical Underdevelopment Jeffrey D. Sachs  

E-print Network

climates. Using geographic information system (GIS) mapping, the paper presents evidence that production of agriculture and health, and this in turn opened a substantial income gap between climate zones. The difficulty amplified because poor public health and weak agricultural technology in the tropics have combined to slow

305

Tropical Biological Drawings with Notes.  

ERIC Educational Resources Information Center

The annotated illustrations of biological specimens useful for illustrating the "tropical" topics dealt with in African secondary school biology courses are designed to serve a two-fold purpose. The diagrams are intended to show the pupil the structures he should be looking for in his laboratory work, with the textual material being an addition to…

Mitchelmore, June A.

306

Skin Diseases in the Tropics.  

ERIC Educational Resources Information Center

Common skin diseases are prevalent in tropical countries because of extreme weather conditions, mediocre hygiene, and lack of adequate treatment of infectious dermatoses. This guide describes the major endemic skin diseases and their signs for the purpose of helping unspecialized health agents train themselves and determine when a patient should…

Mahe, Antoine; And Others

1994-01-01

307

Tropical Cyclone Report Hurricane Irene  

E-print Network

Tropical Cyclone Report Hurricane Irene (AL092011) 21-28 August 2011 Lixion A. Avila and John Cangialosi National Hurricane Center 14 December 2011 Updated 19 December 2011 to correct landfall pressure as a category 3 hurricane (on the Saffir-Simpson Hurricane Wind Scale) but gradually weakened after crossing

308

Tropical Cyclone Report Hurricane Katrina  

E-print Network

1 Tropical Cyclone Report Hurricane Katrina 23-30 August 2005 Richard D. Knabb, Jamie R. Rhome, and damage cost estimates Katrina was an extraordinarily powerful and deadly hurricane that carved a wide deadliest hurricanes to ever strike the United States. Katrina first caused fatalities and damage

309

Tropical Animal Tour Packet. Metro.  

ERIC Educational Resources Information Center

This packet is designed to assist teachers in creating a tropical animals lesson plan that centers around a visit to the zoo. A teacher packet is divided into eight parts: (1) goals and objectives; (2) what to expect at the zoo; (3) student activities (preparatory activities, on-site activities, and follow-up activities); (4) background…

Metro Washington Park Zoo, Portland, OR. Educational Services Div.

310

Tropical Storm Allison Progression (WMS)  

NSDL National Science Digital Library

Tropical Storm Allison began just five days into the 2001 hurricane season. Allison formed in the warm waters of the Gulf of Mexico, and dumped an enormous amount of rain on Texas, Louisiana, Florida, and other states in the southeastern United States.

Eric Sokolowsky

2004-03-11

311

The tropical special observing system  

NASA Technical Reports Server (NTRS)

The performance summaries of the components of the Tropical Observing System is covered. Some of the more important points concerning the quality of the data from each of the observing systems is emphasized, and examples of the assimilation of the Level IIb data are shown.

Julian, P. R.

1985-01-01

312

8, 69837016, 2008 Tropical vertical  

E-print Network

MIPAS-STR measurements over Brazil in February 2005 and the role of PAN in the UT tropical NOy.hoepfner@imk.fzk.de) Published by Copernicus Publications on behalf of the European Geosciences Union. 6983 #12;ACPD 8, 698355-Geophysica. The measurements were performed close to Arac¸atuba, Brazil, on 17 February 2005

Paris-Sud XI, Université de

313

May 1, 2006 Page 1 of 3 Rodent Control After a Disaster  

E-print Network

environmental sanitation, food storage, rodent-proofing, poisoning, and trapping. Inside the Home · Keep food pests that can spread disease, contaminate food, and destroy property. However, as a result of food, water, and shelter. As the rodents settle into new areas, they will build colonies and reproduce

314

RODENT COMMUNITIES IN ACTIVE AND INACTIVE COLONIES OF BLACK-TAILED PRAIRIE DOGS IN SHORTGRASS STEPPE  

Microsoft Academic Search

Black-tailed prairie dogs (Cynomys ludovicianus) alter shortgrass-steppe landscapes in ways that are expected to affect other mammals. I sampled rodent populations at 31 sites on the Pawnee National Grasslands, Colorado, including 18 active colonies, 6 colonies that had been unoccupied for .6 years (inactive), and 7 grassland sites without prairie dogs (controls). Rodents were livetrapped for 4 consecutive nights at

Paul Stapp

2007-01-01

315

NATURAL RODENT HOST ASSOCIATIONS OF GUANARITO AND PIRITAL VIRUSES (FAMILY ARENAVIRIDAE) IN CENTRAL VENEZUELA  

Microsoft Academic Search

The objective of this study was to elucidate the natural rodent host relationships of Guanarito and Pirital viruses (family Arenaviridae) in the plains of central Venezuela. Ninety-two arenavirus isolates from 607 animals, representing 10 different rodent species, were characterized to the level of serotype. The 92 isolates comprised 19 Guanarito virus strains and 73 Pirital virus strains. The 19 Guanarito

CHARLES F. FULHORST; MICHAEL D. BOWEN; ROSA ALBA SALAS; GLORIA DUNO; ANTONIO UTRERA; THOMAS G. KSIAZEK; NURIS M. C. DE MANZIONE; EDITH DE MILLER; CLOVIS VASQUEZ; CLARENCE J. PETERS; ROBERT B. TESH

1999-01-01

316

Pattern and dynamics of rodent damage to lowland irrigated rice crops in An Giang, Vietnam  

Microsoft Academic Search

Rodents are an important pre-harvest pest of lowland irrigated rice. Estimates of the area of damage to rice crops by 17 important rice pests were collected every week by the Plant Protection Department of An Giang province in the Mekong Delta of Vietnam. We examined 5 years of data to reveal that rodents were ranked fourth with 4.2% of rice

Peter R. Brown; Nguyen Thi My Phung

2010-01-01

317

Density estimation for small mammals from livetrapping grids: rodents in northern Canada  

E-print Network

on livetrapping grids with 4 estimators applied to 3 species of boreal forest and 3 species of tundra rodents), and 56 trapping sessions from tundra areas of Herschel Island and Komakuk Beach in northern Yukon (n 5 1 to 25 animals/ha. For tundra rodents both boundary-strip methods produced density estimates smaller than

Krebs, Charles J.

318

Programmed versus stimulus-driven antiparasitic grooming in a desert rodent  

Microsoft Academic Search

We tested 2 hypotheses concerning regulation of grooming in flea-infested rodents and examined if 2 grooming components, scan and scratch grooming, are controlled by programmed and stimulus-driven regulation, respectively. The programmed grooming hypothesis proposes central programming that periodically evokes a bout of grooming to remove ectoparasites before they are attached and predicts that juvenile rodents 1) regardless of infestation status

Hadas Hawlena; Dikla Bashary; Zvika Abramsky; Irina S. Khokhlova; Boris R. Krasnov

2008-01-01

319

shuttle-based system. Advanced capabilities of the new Rodent Habitat include providing  

E-print Network

to the space station. The second is the Animal Access Unit that will be used to transfer the rodents upon ar and Space Administration Rodent Habitat Studying Animals in Space Aboard the International Space Station shuttle. The International Space Station is the first essen- tially "permanent" orbiting science laborato

Waliser, Duane E.

320

RODENT MANAGEMENT FOR SURFACE DRIP IRRIGATION TUBING IN CORN, COTTON, AND PEANUT  

Technology Transfer Automated Retrieval System (TEKTRAN)

Surface drip (SD) irrigation of field crops has been gaining interest in the farming community. However, rodent damage is one of the major drawbacks for SD acceptance. This research documents the cost of repairing drip tubing and effectiveness of several rodent control methods. Four sites were used ...

321

Anti-erosion stone bunds influence rodent dynamics and crop damage in Ethiopian highlands  

NASA Astrophysics Data System (ADS)

In areas of subsistence agriculture, a variety of soil conservation methods have been implemented in the last few decades to improve crop yields, however these can have unintended consequences such as providing habitat for rodent pests. We studied rodent population dynamics and estimated crop damage in high and low stone bund density fields for four cropping seasons in Tigray highlands, northern Ethiopia. Stone bunds are physical structures for soil and water conservation, and potentially habitat for rodents. We used a general model to relate the proportion of crop damage to rodent abundance, stone bund density and crop stages. We found a positive correlation between rodent abundance and crop damage, and significant variation in rodent abundance and crop damage between high and low stone bund density fields. Furthermore, crop damage also varied significantly between crop stages. We concluded that Mastomys awashensis and Arvicanthis dembeensis were the two most important crop pests in the highlands causing significant damage. Fields with high stone bund density (~10 m average distance apart) harbor more rodents and endure a significantly higher proportion of crop damage compared to fields with lower stone bund density (~15 m average distance apart). The fact that rodent abundances peaked during the reproductive stage of the crop and around harvest implies the need for management intervention before these crop stages are attained.

Meheretu, Yonas; Welegerima, Kiros; Teferi, Mekonen; Yirga, Gidey; Haile, Mitiku; Sluydts, Vincent; Bauer, Hans; Nyssen, Jan; Deckers, Jozef; Leirs, Herwig

2014-05-01

322

Effectiveness of six species of rodents as dispersers of singleleaf piñon pine ( Pinus monophylla )  

Microsoft Academic Search

The effectiveness of six species of rodents as dispersers of singleleaf piñon pine (Pinus monophylla) was investigated in field enclosures. The rodent species were Panamint kangaroo rat (Dipodomys panamintinus), Great Basin pocket mouse (Perognathus parvus), pinyon mouse (Peromyscus truei), deer mouse (Peromyscus maniculatus), least chipmunk (Tamias minimus), and white-tailed antelope ground squirrel (Ammospermophilus leucurus). Five measures of seed harvesting and

Jennifer L. Hollander; Stephen B. Vander Wall

2004-01-01

323

Teasing Apart the Effects of Seed Size and Energy Content on Rodent Scatter-Hoarding Behavior  

PubMed Central

Scatter-hoarding rodents are known to play a crucial role in the seed dispersal of many plant species. Numerous studies have indicated that both seed size and the energy content of seeds can affect rodent foraging behavior. However, seed size is usually associated with energy content per seed, making it difficult to isolate how seed size and energy affect rodent foraging preferences. This study used 99 treatments of artificial seeds (11 seed sizes×9 levels of energy content) to tease apart the effect of seed size and energy content on rodent seed-caching behavior. Both seed traits showed significant effects, but their details depended on the stage of the rodent foraging process. Seeds with higher energy content were harvested more rapidly while seed size only had a modest effect on harvest rate. However, after harvesting, seed size showed a much stronger effect on rodent foraging behavior. Rodents’ choice of which seeds to remove and cache, as well as seed dispersal distance, seemed to reflect an optimal seed size. Our findings could be adapted in future studies to gain a better understanding of scatter-hoarding rodent foraging behavior, and the co-evolutionary dynamics between plant seed production and seed dispersers. PMID:25350369

Wang, Bo; Yang, Xiaolan

2014-01-01

324

Diversity of gastrointestinal helminths among murid rodents from northern and northeastern Thailand.  

PubMed

The presence of gastrointestinal helminths (GI helminths) was investigated among 725 murid rodents, trapped in various habitats of Nan, Loei and Buri Ram Provinces, Thailand. The study revealed 17 species of rodents infected with 21 species or taxonomic groups of parasites (3 trematodes, 3 cestodes, 14 nematodes and 1 acanthocephalan). The overall prevalence of infection was 57.7% (418/725). Of the gastrointestinal (GI) helminths, the dominant parasitic group was members of the family Trichostrongylidae (24.3%), followed by the cestodes Raillietina sp (17.1%) and Hymenolepis diminuta (8.6%) and the nematode Syphacia muris (8.6%). The GI helminthic infection rates were highest in Mus caroli (81.8%), Mus cervicolor (76.5%), Leopoldamys edwardsi (75.0%), Bandicota indica (71.5%) and Bandicota savilei (71.4%). Highest rodent species richness (RSR) and helminth species richness (HSR) rates were found in Loei, followed by Nan and Buri Ram. The helminth prevalence rate was higher in rodents from Nan, followed by rodents from Loei and Buri Ram. Rodents from irrigated fields had the highest infection rates followed by rodents from upland or dry agricultural areas, forests and domestic habitats. Raillietina sp, Rodentolepis nana (syn. Hymenolepis nana), Hymenolepis diminuta, Moniliformis moniliformis and Cyclodontostomum purvisi, considered zoonotic parasites, were mainly found in rodents from domestic habitats and lowland irrigated fields. PMID:23082550

Chaisiri, Kittipong; Chaeychomsri, Win; Siruntawineti, Jindawan; Ribas, Alexis; Herbreteau, Vincent; Morand, Serge

2012-01-01

325

Enhanced Transmission of Drug-Resistant Parasites to Mosquitoes following Drug Treatment in Rodent Malaria  

E-print Network

following Drug Treatment in Rodent Malaria. PLoS ONE 7(6): e37172. doi:10.1371/journal.pone.0037172 EditorEnhanced Transmission of Drug-Resistant Parasites to Mosquitoes following Drug Treatment in Rodent Malaria Andrew S. Bell1 , Silvie Huijben1 , Krijn P. Paaijmans1 , Derek G. Sim1 , Brian H. K. Chan1

Read, Andrew

326

Competitive release in microhabitat use among coexisting desert rodents: a natural experiment  

Microsoft Academic Search

Competitive release among desert rodents on sand dunes of differing species richness was examined in the Great Basin and Mohave Deserts, USA. Expansions in microhabitat use were exhibited by the kangaroo rats Dipodomys ordii and D. merriami (granivorous heteromyid rodents, weighing 49 and 42 g, respectively) as the number of coexisting heteromyid species decreased geographically. Perognathus longimembris, the only common

Eric Larsen

1986-01-01

327

Translating Research from Animal Models: Does It Matter that Our Rodents are So Cold?  

EPA Science Inventory

Does it matter that preclinical rodent models are routinely housed below their thermoneutral zone and are thereby cold-stressed? We compile evidence showing that rodents housed below their thermoneutral zone are cold-stressed, hypermetalbolic, hypertensive, sleep-deprived, obesi...

328

Nongastric H-K-ATPase in rodent prostate: lobe-specific expression and apical localization  

E-print Network

Nongastric H-K-ATPase in rodent prostate: lobe-specific expression and apical localization NIKOLAY. Modyanov. Nongastric H-K-ATPase in rodent prostate: lobe-specific expression and apical localiza- tion. Am is not well characterized. Rat nongastric H-K-ATPase is expressed at high levels in distal colon surface cell

Brand, Paul H.

329

STUDY OF THE CHEMICAL AND BEHAVIORAL TOXICOLOGY OF SUBSTITUTE CHEMICALS IN MICROTINE RODENTS  

EPA Science Inventory

Acute oral LD50 and 30-day dietary subacute LC50 studies of 10 selected pesticides were evaluated in microtine rodents. As a means to developing new animal model systems, four species of microtine rodents including Microtus ochrogaster (MO), Microtus canicaudus (MC), Microtus pen...

330

Rodent and Flea Abundance Fail to Predict a Plague Epizootic in Black-Tailed Prairie Dogs  

E-print Network

Rodent and Flea Abundance Fail to Predict a Plague Epizootic in Black-Tailed Prairie Dogs Robert at a number of prairie dog colony sites in Boulder County, Colorado, before, during, and after a local plague epizootic to see if high rodent or flea abundance was associated with plague-affected colonies when compared

Collinge, Sharon K.

331

Sound Localization in a Predatory Rodent, the Northern Grasshopper Mouse (Onychomys leucogaster )  

Microsoft Academic Search

A comparison of the ability of mammals to localize sound revealed that among the animals examined to date, none of the rodents have been able to localize as accurately as the carnivores. Because all of these rodents are prey animals, the question arises as to whether their poor localization acuity is a phyletic trait of Rodentia or whether it is

Rickye S. Heffner; Henry E. Heffner

1988-01-01

332

Rodent repellent studies. IV. Preparation and properties of trinitrobenzene-aryl amine complexes  

USGS Publications Warehouse

Data are presented on methods of preparation, chemical arid physical characteristics, toxicity, and repellency to rodents of complexes of symmetrical trinitrohenzene with various aromatic amines: When applied in suitable carriers or incorporated in plastic .films, members of this series ofmaterials were shown to offer significant increases in time required by wild rodents to damage common packaging materials.

DeWitt, J.B.; Bellack, E.; Welch, J.F.

1953-01-01

333

Diffusion and home range parameters for rodents: Peromyscus maniculatus in New Mexico  

E-print Network

Diffusion and home range parameters for rodents: Peromyscus maniculatus in New Mexico G. Abramson a in the field. A basic assumption of that model is that the rodent movement may be regarded as diffusive and characterized by a parameter D, the diffusion coefficient. Various contributions to the understanding of animal

334

DEVELOPING A PREDICTIVE SIMULATION MODEL FOR ANTIANDROGEN IMPACTS ON RODENT PROSTATE  

EPA Science Inventory

Developing a predictive simulation model for antiandrogen impacts on rodent prostate HA Barton1, RW Setzer1, LK Potter1,2 1US EPA, ORD, NHEERL, ETD, PKB, Research Triangle Park, NC and 2Curriculum in Toxicology, UNC, Chapel Hill, NC Alterations in rodent prostate wei...

335

Gene Expression in the Rodent Brain is Associated with Its Regional Connectivity  

E-print Network

Gene Expression in the Rodent Brain is Associated with Its Regional Connectivity Lior Wolf1 *, Chen The putative link between gene expression of brain regions and their neural connectivity patterns of a prototypical mammalian rodent brain, using a combination of rat brain regional connectivity data with gene

Wolf, Lior

336

Prairie Rattlesnakes (Crotalus viridis) Respond to Rodent Blood with Chemosensory Searching  

Microsoft Academic Search

In Experiment I, homogenized rodent tissue was applied to the lips of prairie rattlesnakes (Crotalus viridis). This treatment produced elevated rates of tongue flicking compared to controls that received water, but the elevations seen following stimulation with homogenate were not as large as those seen after snakes struck prey. In Experiment II, water, rodent blood, and integumentary cues were applied

David Chiszar; Grant Hobika; Hobart M. Smith

1993-01-01

337

Tropical cyclogenesis in a tropical wave critical layer: easterly waves  

NASA Astrophysics Data System (ADS)

The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because its cat's eye provides (i) a region of cyclonic vorticity and weak deformation by the resolved flow, (ii) containment of moisture entrained by the developing gyre and/or lofted by deep convection therein, (iii) confinement of mesoscale vortex aggregation, (iv) a predominantly convective type of heating profile, and (v) maintenance or enhancement of the parent wave until the vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. The entire sequence is likened to the development of a marsupial infant in its mother's pouch. These ideas are formulated in three new hypotheses describing the flow kinematics and dynamics, moist thermodynamics and wave/vortex interactions comprising the "marsupial paradigm". A survey of 55 named tropical storms in 1998-2001 reveals that actual critical layers sometimes resemble the ideal east-west train of cat's eyes, but are usually less regular, with one or more recirculation regions in the co-moving frame. It is shown that the kinematics of isolated proto-vortices carried by the wave also can be visualized in a frame of reference translating at or near the phase speed of the parent wave. The proper translation speeds for wave and vortex may vary with height owing to vertical shear and wave-vortex interaction. Some implications for entrainment/containment of vorticity and moisture in the cat's eye are discussed from this perspective, based on the observational survey.

Dunkerton, T. J.; Montgomery, M. T.; Wang, Z.

2009-08-01

338

Black Swan Tropical Cyclones  

NASA Astrophysics Data System (ADS)

Virtually all assessments of tropical cyclone risk are based on historical records, which are limited to a few hundred years at most. Yet stronger TCs may occur in the future and at places that have not been affected historically. Such events lie outside the realm of historically based expectations and may have extreme impacts. Their occurrences are also often made explainable after the fact (e.g., Hurricane Katrina). We nickname such potential future TCs, characterized by rarity, extreme impact, and retrospective predictability, "black swans" (Nassim Nicholas Taleb, 2007). As, by definition, black swan TCs have yet to happen, statistical methods that solely rely on historical track data cannot predict their occurrence. Global climate models lack the capability to predict intense storms, even with a resolution as high as 14 km (Emanuel et al. 2010). Also, most dynamic downscaling methods (e.g., Bender et al. 2010) are still limited in horizontal resolution and are too expensive to implement to generate enough events to include rare ones. In this study, we apply a simpler statistical/deterministic hurricane model (Emanuel et al. 2006) to simulate large numbers of synthetic storms under a given (observed or projected) climate condition. The method has been shown to generate realistic extremes in various basins (Emanuel et al. 2008 and 2010). We also apply a hydrodynamic model (ADCIRC; Luettich et al. 1992) to simulate the storm surges generated by these storms. We then search for black swan TCs, in terms of the joint wind and surge damage potential, in the generated large databases. Heavy rainfall is another important TC hazard and will be considered in a future study. We focus on three areas: Tampa Bay in the U.S., the Persian Gulf, and Darwin in Australia. Tampa Bay is highly vulnerable to storm surge as it is surrounded by shallow water and low-lying lands, much of which may be inundated by a storm tide of 6 m. High surges are generated by storms with a broad spectrum of characteristics in our synthetic database, although no large surge has been recorded historically as only one moderate storm passed by the area. Tampa black swans are identified as those that move northward parallel to the west Florida coast with high intensities and resonant with the Florida-shelf edge waves to generate extreme surges up to 10 m in Tampa Bay. The Arabian Sea area has sea surface temperatures warm enough to support the development of severe TCs, but TC development has been limited by low humidity and high wind shear, and only one recorded TC (super cyclonic storm Gonu in 2007) moved close to the Persian Gulf, making landfall in Oman and Iran. Our analysis shows that black swan TCs can originate within the Persian Gulf and make landfall with high intensities in populous places; extreme surges over 9 m for Abu Dubai and Doha and over 7 m for Dubai are possible. Darwin experienced immense devastation from Cyclone Tracy of 1974, but the damage was mainly due to the strong winds (the surge was only about 1.6 m). Our analysis includes extremely intense black swan TCs that make landfall just south of Darwin, generating surges above 10 m; these results may prompt the city to reconsider its TC risk. We are currently analyzing the join probability of the extreme wind and surge of these black swan TCs to more clearly assess their full damage potentials.

Emanuel, K.; Lin, N.

2012-12-01

339

Tropical Storm Erin  

NASA Technical Reports Server (NTRS)

Location: The Atlantic Ocean 210 miles south of Galveston, Texas Categorization: Tropical Storm Sustained Winds: 40 mph (60 km/hr)

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Infrared ImageMicrowave Image

Infrared Images Because infrared radiation does not penetrate through clouds, AIRS infrared images show either the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. In cloud-free areas the AIRS instrument will receive the infrared radiation from the surface of the Earth, resulting in the warmest temperatures (orange/red).

Microwave Images In the AIRS microwave imagery, deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. On the other hand, land appears much warmer due to its high radiation emissivity.

Microwave radiation from Earth's surface and lower atmosphere penetrates most clouds to a greater or lesser extent depending upon their water vapor, liquid water and ice content. Precipitation, and ice crystals found at the cloud tops where strong convection is taking place, act as barriers to microwave radiation. Because of this barrier effect, the AIRS microwave sensor detects only the radiation arising at or above their location in the atmospheric column. Where these barriers are not present, the microwave sensor detects radiation arising throughout the air column and down to the surface. Liquid surfaces (oceans, lakes and rivers) have 'low emissivity' (the signal isn't as strong) and their radiation brightness temperature is therefore low. Thus the ocean also appears 'low temperature' in the AIRS microwave images and is assigned the color blue. Therefore deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. Land appears much warmer due to its high radiation emissivity.

Visible/Near-Infrared Images The AIRS instrument suite contains a sensor that captures radiation in four bands of the visible/near-infrared portion of the electromagetic spectrum. Data from three of these bands are combined to create 'visible' images similar to a snapshot taken with your camera.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

2007-01-01

340

Geographic Distribution of Hantaviruses Associated with Neotomine and Sigmodontine Rodents, Mexico  

PubMed Central

To increase our knowledge of the geographic distribution of hantaviruses associated with neotomine or sigmodontine rodents in Mexico, we tested 876 cricetid rodents captured in 18 Mexican states (representing at least 44 species in the subfamily Neotominae and 10 species in the subfamily Sigmodontinae) for anti-hantavirus IgG. We found antibodies against hantavirus in 35 (4.0%) rodents. Nucleotide sequence data from 5 antibody-positive rodents indicated that Sin Nombre virus (the major cause of hantavirus pulmonary syndrome [HPS] in the United States) is enzootic in the Mexican states of Nuevo León, San Luis Potosí, Tamaulipas, and Veracruz. However, HPS has not been reported from these states, which suggests that in northeastern Mexico, HPS has been confused with other rapidly progressive, life-threatening respiratory diseases. Analyses of nucleotide sequence data from 19 other antibody-positive rodents indicated that El Moro Canyon virus and Limestone Canyon virus are geographically widely distributed in Mexico. PMID:22469569

Milazzo, Mary L.; Cajimat, Maria N.B.; Romo, Hannah E.; Estrada-Franco, Jose G.; Iñiguez-Dávalos, L. Ignacio; Bradley, Robert D.

2012-01-01

341

Rodents on pig and chicken farms – a potential threat to human and animal health  

PubMed Central

Rodents can cause major problems through spreading various diseases to animals and humans. The two main species of rodents most commonly found on farms around the world are the house mouse (Mus musculus) and the brown rat (Rattus norvegicus). Both species are omnivorous and can breed year-round under favourable conditions. This review describes the occurrence of pathogens in rodents on specialist pig and chicken farms, which are usually closed units with a high level of bio-security. However, wild rodents may be difficult to exclude completely, even from these sites, and can pose a risk of introducing and spreading pathogens. This article reviews current knowledge regarding rodents as a hazard for spreading disease on farms. Most literature available regards zoonotic pathogens, while the literature regarding pathogens that cause disease in farm animals is more limited. PMID:22957130

Backhans, Annette; Fellström, Claes

2012-01-01

342

Pollen analyses from a 50 000-yr rodent midden series in the southern Atacama Desert (25° 300' S)  

USGS Publications Warehouse

Precipitation in northern Chile is controlled by two great wind belts—the southern westerlies over the southern Atacama and points south (>24° S) and the tropical easterlies over the northern and central Atacama Desert (16–24° S). At the intersection of these summer and winter rainfall regimes, respectively, is a Mars-like landscape consisting of expansive surfaces devoid of vegetation (i.e. absolute desert) except in canyons that originate high enough to experience runoff once every few years. Pollen assemblages from 39 fossil rodent middens in one of these canyons, Quebrada del Chaco (25° 30' S), were used to infer the history of vegetation and precipitation at three elevations (2670–800 m; 3100–3200 m; 3450–3500 m) over the past 50 000 years. When compared to modern conditions and fossil records to the north and south, the pollen evidence indicates more winter precipitation at >52, 40–33, 24–17 k cal.yrBP, more precipitation in both seasons at 17–14 k cal. yr BP, and more summer precipitation from 14–11 k cal. yr BP. Younger middens are scarce at Quebrada del Chaco, and the few Holocene samples indicate hyperarid conditions comparable to today. The only exception is a pollen assemblage that indicates a brief but significant interlude of increased winter precipitation in the last millennium.

Maldonado, Antonio; Betancourt, Julio L.; Latorre, Claudio; Villagran, Carolina

2005-01-01

343

Effects of Fat and Protein Levels on Foraging Preferences of Tannin in Scatter-Hoarding Rodents  

PubMed Central

Both as consumers and dispersers of seeds, scatter-hoarding rodents often play an important role in the reproductive ecology of many plant species. However, the seeds of many plant species contain tannins, which are a diverse group of water-soluble phenolic compounds that have a high affinity for proteins. The amount of tannins in seeds is expected to affect rodent foraging preferences because of their major impact on rodent physiology and survival. However, variable results have been obtained in studies that evaluated the effects of tannin on rodent foraging behavior. Hence, in this study, we aimed to explain these inconsistent results and proposed that a combination of seed traits might be important in rodent foraging behavior, because it is difficult to distinguish between the effects of individual traits on rodent foraging behavior and the interactions among them. By using a novel artificial seed system, we manipulated seed tannin and fat/protein levels to examine directly the univariate effects of each component on the seed preferences of free-ranging forest rats (Apodemus latronum and Apodemus chevrieri) during the behavioral process of scatter hoarding. Our results showed that both tannin and fat/protein had significant effects on rodent foraging behavior. Although only a few interactive effects of tannin and fat/protein were recorded, higher concentrations of both fat and protein could attenuate the exclusion of seeds with higher tannin concentrations by rodents, thus influencing seed fate. Furthermore, aside from the concentrations of tannin, fat, and protein, numerous other traits of plant seeds may also influence rodent foraging behavior. We suggest that by clarifying rodent foraging preferences, a better understanding of the evolution of plant seed traits may be obtained because of their strong potential for selective pressure. PMID:22808217

Wang, Bo; Chen, Jin

2012-01-01

344

Next-Generation Sequencing for Rodent Barcoding: Species Identification from Fresh, Degraded and Environmental Samples  

PubMed Central

Rodentia is the most diverse order among mammals, with more than 2,000 species currently described. Most of the time, species assignation is so difficult based on morphological data solely that identifying rodents at the specific level corresponds to a real challenge. In this study, we compared the applicability of 100 bp mini-barcodes from cytochrome b and cytochrome c oxidase 1 genes to enable rodent species identification. Based on GenBank sequence datasets of 115 rodent species, a 136 bp fragment of cytochrome b was selected as the most discriminatory mini-barcode, and rodent universal primers surrounding this fragment were designed. The efficacy of this new molecular tool was assessed on 946 samples including rodent tissues, feces, museum samples and feces/pellets from predators known to ingest rodents. Utilizing next-generation sequencing technologies able to sequence mixes of DNA, 1,140 amplicons were tagged, multiplexed and sequenced together in one single 454 GS-FLX run. Our method was initially validated on a reference sample set including 265 clearly identified rodent tissues, corresponding to 103 different species. Following validation, 85.6% of 555 rodent samples from Europe, Asia and Africa whose species identity was unknown were able to be identified using the BLASTN program and GenBank reference sequences. In addition, our method proved effective even on degraded rodent DNA samples: 91.8% and 75.9% of samples from feces and museum specimens respectively were correctly identified. Finally, we succeeded in determining the diet of 66.7% of the investigated carnivores from their feces and 81.8% of owls from their pellets. Non-rodent species were also identified, suggesting that our method is sensitive enough to investigate complete predator diets. This study demonstrates how this molecular identification method combined with high-throughput sequencing can open new realms of possibilities in achieving fast, accurate and inexpensive species identification. PMID:23144869

Galan, Maxime; Pagès, Marie; Cosson, Jean-François

2012-01-01

345

Ground-based rodent control in a remote Hawaiian rainforest on Maui  

USGS Publications Warehouse

Effective control of introduced mammalian predators is essential to the recovery of native bird species in Hawai'i. Between August 1996 and December 2004, introduced rodents were controlled within three home ranges of the Po'ouli Melamprosops phaeosoma, a critically endangered Hawaiian honeycreeper. Rats were controlled using a combination of ground-based rodenticide (0.005% diphacinone) application and snap traps. Beginning in August 2001, we monitored the effectiveness of these rodent control efforts. Relative abundances of Black Rats Rattus rattus and Polynesian Rats R. exulans were measured in each of five snap-trapping grids seven times over a 35-month period. Rat populations decreased inside of the rodent control areas, but control effectiveness differed between rat species. During the first year of monitoring, target control levels for R. rattus were consistently achieved in only one of the rodent control areas. Control techniques were refined in areas failing to meet targets. Subsequently, we achieved target control levels for R. rattus more consistently in all three rodent control areas. However, relative abundances of R. exulans did not differ between rodent control and reference areas, indicating that our rodent control techniques were insufficient to reduce population levels of this species. These findings signify a need for further improvement of rodent control methods in Hawai'i, especially for Polynesian Rats, and demonstrate the critical importance of periodic monitoring of the response of rodent populations to management. In the future, managers may need to design rodent control operations targeting R. rattus and R. exulans independently to achieve best results.

Malcolm, T.R.; Swinnerton, K.J.; Groombridge, J.J.; Sparklin, B.D.; Brosius, C.N.; Vetter, J.P.; Foster, J.T.

2008-01-01

346

Rodent and Flea Abundance Fail to Predict a Plague Epizootic in Black-Tailed Prairie Dogs  

PubMed Central

Abstract Small rodents are purported to be enzootic hosts of Yersinia pestis and may serve as sources of infection to prairie dogs or other epizootic hosts by direct or flea-mediated transmission. Recent research has shown that small rodent species composition and small rodent flea assemblages are influenced by the presence of prairie dogs, with higher relative abundance of both small rodents and fleas at prairie dog colony sites compared to grasslands without prairie dogs. However, it is unclear if increased rodent or flea abundance predisposes prairie dogs to infection with Y. pestis. We tracked rodent and flea occurrence for 3 years at a number of prairie dog colony sites in Boulder County, Colorado, before, during, and after a local plague epizootic to see if high rodent or flea abundance was associated with plague-affected colonies when compared to colonies that escaped infection. We found no difference in preepizootic rodent abundance or flea prevalence or abundance between plague-positive and plague-negative colonies. Further, we saw no significant before-plague/after-plague change in these metrics at either plague-positive or plague-negative sites. We did, however, find that small rodent species assemblages changed in the year following prairie dog die-offs at plague-affected colonies when compared to unaffected colonies. In light of previous research from this system that has shown that landscape features and proximity to recently plagued colonies are significant predictors of plague occurrence in prairie dogs, we suggest that landscape context is more important to local plague occurrence than are characteristics of rodent or flea species assemblages. PMID:20158331

Collinge, Sharon K.; Ray, Chris; Gage, Ken L.

2010-01-01

347

Predation on native birds in New Zealand beech forests: the role of functional relationships between Stoats Mustela erminea and rodents  

Microsoft Academic Search

In the Holarctic, predation by mustelids on birds is often linked to population cycles of rodents (especially voles and lemmings) because birds may be buffered against mustelid predation at high rodent densities. By contrast, interguild relationships between introduced mustelids and rodents can have very different consequences for native birds in ecosystems where mustelids have been introduced. Here, we consider the

PIRAN C. L. WHITE; CAROLYN M. KING

2006-01-01

348

Identification of novel anelloviruses with broad diversity in UK rodents.  

PubMed

Anelloviruses are a family of small circular ssDNA viruses with a vast genetic diversity. Human infections with the prototype anellovirus, torque teno virus (TTV), are ubiquitous and related viruses have been described in a number of other mammalian hosts. Despite over 15 years of investigation, there is still little known about the pathogenesis and possible disease associations of anellovirus infections, arising in part due to the lack of a robust cell culture system for viral replication or tractable small-animal model. We report the identification of diverse anelloviruses in several species of wild rodents. The viruses are highly prevalent in wood mice (Apodemus sylvaticus) and field voles (Microtus agrestis), detectable at a low frequency in bank voles (Myodes glareolus), but absent from house mice (Mus musculus). The viruses identified have a genomic organization consistent with other anelloviruses, but form two clear phylogenetic groups that are as distinct from each other as from defined genera. PMID:24744300

Nishiyama, Shoko; Dutia, Bernadette M; Stewart, James P; Meredith, Anna L; Shaw, Darren J; Simmonds, Peter; Sharp, Colin P

2014-07-01

349

Seroepidemiologic studies of hantavirus infection among wild rodents in California.  

PubMed Central

A total of 4,626 mammals were serologically tested for antibodies to Sin Nombre virus. All nonrodent species were antibody negative. Among wild rodents, antibody prevalence was 8.5% in murids, 1.4% in heteromyids, and < 0.1% in sciurids. Of 1,921 Peromyscus maniculatus (deer mice), 226 (11.8%) were antibody positive, including one collected in 1975. The highest antibody prevalence (71.4% of 35) was found among P. maniculatus on Santa Cruz Island, off the southern California coast. Prevalence of antibodies among deer mice trapped near sites of human cases (26.8% of 164) was significantly higher than that of mice from other sites (odds ratio = 4.5; 95% confidence interval = 1.7, 11.6). Antibody prevalence increased with rising elevation (> 1,200 meters) and correlated with a spatial cluster of hantavirus pulmonary syndrome cases in the Sierra Nevada. PMID:9204301

Jay, M.; Ascher, M. S.; Chomel, B. B.; Madon, M.; Sesline, D.; Enge, B. A.; Hjelle, B.; Ksiazek, T. G.; Rollin, P. E.; Kass, P. H.; Reilly, K.

1997-01-01

350

Dopamine regulation of social choice in a monogamous rodent species.  

PubMed

There is growing appreciation that social decision making in humans is strongly influenced by hedonic and emotional processing. The field of social neuroeconomics has shown that neural systems important for reward are associated with social choice and social preferences in humans. Here, we show that the neurobiology of social preferences in a monogamous rodent species, the prairie vole, is also regulated by neural systems involved in reward and emotional processing. Specifically, we describe how mesolimbic dopamine transmission differentially mediates the formation and maintenance of monogamous pair bonds in this species. Thus, reward processing exerts tremendous regulation over social choice behaviors that serve as the foundation of a rather complex social organization. We conclude that prairie voles are an excellent model system for the neuroscience of social choice and that complex social decision-making can be robustly explained by reward and hedonic processing. PMID:19707518

Aragona, Brandon J; Wang, Zuoxin

2009-01-01

351

?-Cell Generation: Can Rodent Studies Be Translated to Humans?  

PubMed Central

?-cell replacement by allogeneic islet transplantation is a promising approach for patients with type 1 diabetes, but the shortage of organ donors requires new sources of ? cells. Islet regeneration in vivo and generation of ?-cells ex vivo followed by transplantation represent attractive therapeutic alternatives to restore the ?-cell mass. In this paper, we discuss different postnatal cell types that have been envisaged as potential sources for future ?-cell replacement therapy. The ultimate goal being translation to the clinic, a particular attention is given to the discrepancies between findings from studies performed in rodents (both ex vivo on primary cells and in vivo on animal models), when compared with clinical data and studies performed on human cells. PMID:22007286

Carlotti, Françoise; Zaldumbide, Arnaud; Ellenbroek, Johanne H.; Spijker, H. Siebe; Hoeben, Rob C.; de Koning, Eelco J.

2011-01-01

352

Melanocortin Control of Energy Balance: Evidence from Rodent Models  

PubMed Central

Regulation of energy balance is extremely complex, and involves multiple systems of hormones, neurotransmitters, receptors, and intracellular signals. As data have accumulated over the last two decades, the CNS melanocortin system is now identified as a prominent integrative network of energy balance controls in the mammalian brain. Here, we will review findings from rat and mouse models, which have provided an important framework in which to study melanocortin function. Perhaps most importantly, this review attempts for the first time to summarize recent advances in our understanding of the intracellular signaling pathways thought to mediate the action of melanocortin neurons and peptides in control of long term energy balance. Special attention will be paid to the roles of MC4R/MC3R, as well as downstream neurotransmitters within forebrain and hindbrain structures that illustrate the distributed control of melanocortin signaling in energy balance. In addition, distinctions and controversy between rodent species will be discussed. PMID:21553232

De Jonghe, Bart C.; Hayes, Matthew R.; Bence, Kendra K.

2011-01-01

353

Transmission of Guanarito and Pirital Viruses among Wild Rodents, Venezuela  

PubMed Central

Samples from rodents captured on a farm in Venezuela in February 1997 were tested for arenavirus, antibody against Guanarito virus (GTOV), and antibody against Pirital virus (PIRV). Thirty-one (48.4%) of 64 short-tailed cane mice (Zygodontomys brevicauda) were infected with GTOV, 1 Alston’s cotton rat (Sigmodon alstoni) was infected with GTOV, and 36 (64.3%) of 56 other Alston’s cotton rats were infected with PIRV. The results of analyses of field and laboratory data suggested that horizontal transmission is the dominant mode of GTOV transmission in Z. brevicauda mice and that vertical transmission is an important mode of PIRV transmission in S. alstoni rats. The results also suggested that bodily secretions and excretions from most GTOV-infected short-tailed cane mice and most PIRV-infected Alston’s cotton rats may transmit the viruses to humans. PMID:22172205

Milazzo, Mary L.; Cajimat, Maria N.B.; Duno, Gloria; Duno, Freddy; Utrera, Antonio

2011-01-01

354

Identification of novel anelloviruses with broad diversity in UK rodents  

PubMed Central

Anelloviruses are a family of small circular ssDNA viruses with a vast genetic diversity. Human infections with the prototype anellovirus, torque teno virus (TTV), are ubiquitous and related viruses have been described in a number of other mammalian hosts. Despite over 15 years of investigation, there is still little known about the pathogenesis and possible disease associations of anellovirus infections, arising in part due to the lack of a robust cell culture system for viral replication or tractable small-animal model. We report the identification of diverse anelloviruses in several species of wild rodents. The viruses are highly prevalent in wood mice (Apodemus sylvaticus) and field voles (Microtus agrestis), detectable at a low frequency in bank voles (Myodes glareolus), but absent from house mice (Mus musculus). The viruses identified have a genomic organization consistent with other anelloviruses, but form two clear phylogenetic groups that are as distinct from each other as from defined genera. PMID:24744300

Nishiyama, Shoko; Dutia, Bernadette M.; Stewart, James P.; Meredith, Anna L.; Shaw, Darren J.; Simmonds, Peter

2014-01-01

355

Photoperiodic control of circadian activity rhythms in diurnal rodents  

NASA Astrophysics Data System (ADS)

The responses of red squirrels (Tamiasciurus hudsonicus) and eastern chipmunks (Tamias striatus) to complete and skeleton light-dark (LD) cycles were compared. The skeletons, comprised of two 1-h pulses of light per day, effectively simulated the complete photoperiods in the squirrels, but not the chipmunks. Skeleton photoperiods greater than 12-h caused the chipmunks to shift activity from the longer to the shorter of the two intervals between the pulses. To interpret the mechanism of phase control, squirrels and chipmunks were kept in continuous darkness and exposed to 1-h light pulses every 10 days. The time-course of entrainment was also quantified. Both techniques produced light-response curves. The data suggest that the parametric and non-parametric contributions to entrainment are different in these two rodent species.

Kramm, K. R.; Kramm, Deborah A.

1980-03-01

356

Dependence Potential of Tramadol: Behavioral Pharmacology in Rodents  

PubMed Central

Tramadol is an opioid analgesic agent that has been the subject of a series of case reports suggesting potential for misuse or abuse. However, it is not a controlled substance and is not generally considered addictive in Korea. In this study, we examined the dependence potential and abuse liability of tramadol as well as its effect on the dopaminergic and serotonergic systems in rodents. In animal behavioral tests, tramadol did not show any positive effects on the experimental animals in climbing, jumping, and head twitch tests. However, in the conditioned place preference and self-administration tests, the experimental animals showed significant positive responses. Taken together, tramadol affected the neurological systems related to abuse liability and has the potential to lead psychological dependence. PMID:25489425

Cha, Hye Jin; Song, Min Ji; Lee, Kwang-Wook; Kim, Eun Jung; Kim, Young-Hoon; Lee, Yunje; Seong, Won-Keun; Hong, Sa-Ik; Jang, Choon-Gon; Yoo, Han Sang; Jeong, Ho-Sang

2014-01-01

357

Hippocampal lipoprotein lipase regulates energy balance in rodents?  

PubMed Central

Brain lipid sensing is necessary to regulate energy balance. Lipoprotein lipase (LPL) may play a role in this process. We tested if hippocampal LPL regulated energy homeostasis in rodents by specifically attenuating LPL activity in the hippocampus of rats and mice, either by infusing a pharmacological inhibitor (tyloxapol), or using a genetic approach (adeno-associated virus expressing Cre-GFP injected into Lpllox/lox mice). Decreased LPL activity by either method led to increased body weight gain due to decreased locomotor activity and energy expenditure, concomitant with increased parasympathetic tone (unchanged food intake). Decreased LPL activity in both models was associated with increased de novo ceramide synthesis and neurogenesis in the hippocampus, while intrahippocampal infusion of de novo ceramide synthesis inhibitor myriocin completely prevented body weight gain. We conclude that hippocampal lipid sensing might represent a core mechanism for energy homeostasis regulation through de novo ceramide synthesis. PMID:24634821

Picard, Alexandre; Rouch, Claude; Kassis, Nadim; Moullé, Valentine S.; Croizier, Sophie; Denis, Raphaël G.; Castel, Julien; Coant, Nicolas; Davis, Kathryn; Clegg, Deborah J.; Benoit, Stephen C.; Prévot, Vincent; Bouret, Sébastien; Luquet, Serge; Le Stunff, Hervé; Cruciani-Guglielmacci, Céline; Magnan, Christophe

2013-01-01

358

Wheel-running behavior in 12 species of muroid rodents.  

PubMed

The objective of this research was to describe the levels and periodicity of wheel running in 12 species of muroid rodents in order that comparisons could be made among different measures of activity in a variety of species. Six males from each species (Peromyscus polionotus, P. eremicus, P. leucopus, P. maniculatus, P. gossypinus, Microtus pennysylvanicus, M. montanus, M. canicaudus, M. ochrogaster, Calomys callos us, Onychomys leucogaster, and Mus musculus) were tested in running wheels for 14 days, with the amount of running recorded hourly. There were significant species differences in amount of wheel running, with Peromyscus generally running more than Microtus. All species displayed marked nocturnality. Thus, Peromyscus display consistent nocturnality both across species, and for various behavioral patterns measured using a variety of methods. By contrast, Microtus display a nocturnal pattern of wheel running, but not of eating, drinking, and various other behavioral patterns. These differences appear to reflect adaptations related to habit and diet. PMID:24925276

Dewsbury, D A

1980-09-01

359

Amorphous intergranular phases control the properties of rodent tooth enamel  

NASA Astrophysics Data System (ADS)

Dental enamel, a hierarchical material composed primarily of hydroxylapatite nanowires, is susceptible to degradation by plaque biofilm–derived acids. The solubility of enamel strongly depends on the presence of Mg2+, F?, and CO32–. However, determining the distribution of these minor ions is challenging. We show—using atom probe tomography, x-ray absorption spectroscopy, and correlative techniques—that in unpigmented rodent enamel, Mg2+ is predominantly present at grain boundaries as an intergranular phase of Mg-substituted amorphous calcium phosphate (Mg-ACP). In the pigmented enamel, a mixture of ferrihydrite and amorphous iron-calcium phosphate replaces the more soluble Mg-ACP, rendering it both harder and more resistant to acid attack. These results demonstrate the presence of enduring amorphous phases with a dramatic influence on the physical and chemical properties of the mature mineralized tissue.

Gordon, Lyle M.; Cohen, Michael J.; MacRenaris, Keith W.; Pasteris, Jill D.; Seda, Takele; Joester, Derk

2015-02-01

360

Electrically Induced Limbic Seizures: Preliminary Findings in a Rodent Model  

PubMed Central

In epilepsy, novel pharmacological and nonpharmacological treatment approaches are commonly assessed in model systems of acute motor and often generalized seizures. We developed a rodent model with short-term electrical stimulation of the perforant path resulting in stereotyped limbic seizures. Limbic structures play a major role in human intractable epilepsy. In 10 rats, single electrical 5-second and 20-Hz stimuli to the perforant path reliably produced limbic seizures characterized by resting behavior and subtle motor signs. Electrophysiological recordings from the dentate gyrus demonstrated a seizure pattern with 4-Hz to 5-Hz discharges. Multiple inductions of seizures within 72 hours did not alter behavioral and electrophysiological seizure characteristics. Electrophysiological excitatory and inhibitory parameters assessed by evoked single and paired pulses did not change with increasing number of seizures. We present preliminary findings on a new model of electrically induced limbic seizures of mesiotemporal origin. This model may represent a reliable screening tool for new treatment approaches such as deep brain stimulation.

Kowski, Alexander B; Holtkamp, Martin

2015-01-01

361

Dependence potential of tramadol: behavioral pharmacology in rodents.  

PubMed

Tramadol is an opioid analgesic agent that has been the subject of a series of case reports suggesting potential for misuse or abuse. However, it is not a controlled substance and is not generally considered addictive in Korea. In this study, we examined the dependence potential and abuse liability of tramadol as well as its effect on the dopaminergic and serotonergic systems in rodents. In animal behavioral tests, tramadol did not show any positive effects on the experimental animals in climbing, jumping, and head twitch tests. However, in the conditioned place preference and self-administration tests, the experimental animals showed significant positive responses. Taken together, tramadol affected the neurological systems related to abuse liability and has the potential to lead psychological dependence. PMID:25489425

Cha, Hye Jin; Song, Min Ji; Lee, Kwang-Wook; Kim, Eun Jung; Kim, Young-Hoon; Lee, Yunje; Seong, Won-Keun; Hong, Sa-Ik; Jang, Choon-Gon; Yoo, Han Sang; Jeong, Ho-Sang

2014-11-01

362

Modelling cognitive affective biases in major depressive disorder using rodents  

PubMed Central

Major depressive disorder (MDD) affects more than 10% of the population, although our understanding of the underlying aetiology of the disease and how antidepressant drugs act to remediate symptoms is limited. Major obstacles include the lack of availability of good animal models that replicate aspects of the phenotype and tests to assay depression-like behaviour in non-human species. To date, research in rodents has been dominated by two types of assays designed to test for depression-like behaviour: behavioural despair tests, such as the forced swim test, and measures of anhedonia, such as the sucrose preference test. These tests have shown relatively good predictive validity in terms of antidepressant efficacy, but have limited translational validity. Recent developments in clinical research have revealed that cognitive affective biases (CABs) are a key feature of MDD. Through the development of neuropsychological tests to provide objective measures of CAB in humans, we have the opportunity to use ‘reverse translation’ to develop and evaluate whether similar methods are suitable for research into MDD using animals. The first example of this approach was reported in 2004 where rodents in a putative negative affective state were shown to exhibit pessimistic choices in a judgement bias task. Subsequent work in both judgement bias tests and a novel affective bias task suggest that these types of assay may provide translational methods for studying MDD using animals. This review considers recent work in this area and the pharmacological and translational validity of these new animal models of CABs. Linked Articles This article is part of a themed section on Animal Models in Psychiatry Research. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-20 PMID:24467454

Hales, Claire A; Stuart, Sarah A; Anderson, Michael H; Robinson, Emma S J

2014-01-01

363

Arctic Small Rodents Have Diverse Diets and Flexible Food Selection  

PubMed Central

The ecology of small rodent food selection is poorly understood, as mammalian herbivore food selection theory has mainly been developed by studying ungulates. Especially, the effect of food availability on food selection in natural habitats where a range of food items are available is unknown. We studied diets and selectivity of grey-sided voles (Myodes rufocanus) and tundra voles (Microtus oeconomus), key herbivores in European tundra ecosystems, using DNA metabarcoding, a novel method enabling taxonomically detailed diet studies. In order to cover the range of food availabilities present in the wild, we employed a large-scale study design for sampling data on food availability and vole diets. Both vole species had ingested a range of plant species and selected particularly forbs and grasses. Grey-sided voles also selected ericoid shrubs and tundra voles willows. Availability of a food item rarely affected its utilization directly, although seasonal changes of diets and selection suggest that these are positively correlated with availability. Moreover, diets and selectivity were affected by availability of alternative food items. These results show that the focal sub-arctic voles have diverse diets and flexible food preferences and rarely compensate low availability of a food item with increased searching effort. Diet diversity itself is likely to be an important trait and has previously been underrated owing to methodological constraints. We suggest that the roles of alternative food item availability and search time limitations for small rodent feeding ecology should be investigated. Nomenclature Annotated Checklist of the Panarctic Flora (PAF), Vascular plants. Available at: http://nhm2.uio.no/paf/, accessed 15.6.2012. PMID:23826371

Soininen, Eeva M.; Ravolainen, Virve T.; Bråthen, Kari Anne; Yoccoz, Nigel G.; Gielly, Ludovic; Ims, Rolf A.

2013-01-01

364

DNA Barcoding of Sigmodontine Rodents: Identifying Wildlife Reservoirs of Zoonoses  

PubMed Central

Species identification through DNA barcoding is a tool to be added to taxonomic procedures, once it has been validated. Applying barcoding techniques in public health would aid in the identification and correct delimitation of the distribution of rodents from the subfamily Sigmodontinae. These rodents are reservoirs of etiological agents of zoonoses including arenaviruses, hantaviruses, Chagas disease and leishmaniasis. In this study we compared distance-based and probabilistic phylogenetic inference methods to evaluate the performance of cytochrome c oxidase subunit I (COI) in sigmodontine identification. A total of 130 sequences from 21 field-trapped species (13 genera), mainly from southern Brazil, were generated and analyzed, together with 58 GenBank sequences (24 species; 10 genera). Preliminary analysis revealed a 9.5% rate of misidentifications in the field, mainly of juveniles, which were reclassified after examination of external morphological characters and chromosome numbers. Distance and model-based methods of tree reconstruction retrieved similar topologies and monophyly for most species. Kernel density estimation of the distance distribution showed a clear barcoding gap with overlapping of intraspecific and interspecific densities < 1% and 21 species with mean intraspecific distance < 2%. Five species that are reservoirs of hantaviruses could be identified through DNA barcodes. Additionally, we provide information for the description of a putative new species, as well as the first COI sequence of the recently described genus Drymoreomys. The data also indicated an expansion of the distribution of Calomys tener. We emphasize that DNA barcoding should be used in combination with other taxonomic and systematic procedures in an integrative framework and based on properly identified museum collections, to improve identification procedures, especially in epidemiological surveillance and ecological assessments. PMID:24244670

Müller, Lívia; Gonçalves, Gislene L.; Cordeiro-Estrela, Pedro; Marinho, Jorge R.; Althoff, Sérgio L.; Testoni, André. F.; González, Enrique M.; Freitas, Thales R. O.

2013-01-01

365

Pulmonary Toxicity Studies of Lunar Dusts in Rodents  

NASA Technical Reports Server (NTRS)

NASA will build an outpost on the lunar surface for long-duration human habitation and research. The surface of the Moon is covered by a layer of fine, reactive dust, and the living quarters in the lunar outpost are expected to be contaminated by lunar dust. Because the toxicity of lunar dust is not known, NASA has tasked its toxicology laboratory to evaluate the risk of exposure to the dust and to establish safe exposure limits for astronauts working in the lunar habitat. Studies of the pulmonary toxicity of a dust are generally done first in rodents by intratracheal/intrapharyngeal instillation. This toxicity screening test is then followed by an inhalation study, which requires much more of the test dust and is labor intensive. Preliminary results obtained by examining lung lavage fluid from dust-treated mice show that lunar dust was somewhat toxic (more toxic than TiO2, but less than quartz dust). More extensive studies are in progress to further examine lung lavage fluid for biomarkers of toxicity and lung tissues for histopathological lesions in rodents exposed to aged and activated (ground) lunar dust samples. In these studies, reference dusts (TiO2 and quartz) of known toxicities and have industrial exposure limits will be studied in parallel so the relative toxicity of lunar dust can be determined. The results from the instillation studies will be useful for choosing exposure concentrations for the animal inhalation study. The animal inhalation exposure will be conducted with lunar dust simulant prior to the study with the lunar dust. The experiment with the simulate will ensure that the study techniques used with actual lunar dust will be successful. The results of instillation and inhalation studies will reveal the toxicological risk of exposures and are essential for setting exposure limits on lunar dust for astronauts living in the lunar habitat.

Lam, Chiu-wing; James, John T.

2009-01-01

366

DISTRIBUTION OF OXYTOCIN IN THE BRAIN OF A EUSOCIAL RODENT  

PubMed Central

Naked mole-rats are highly social rodents that live in large colonies characterized by a rigid social and reproductive hierarchy. Only one female, the queen, breeds. Most colony members are non-reproductive subordinates that work cooperatively to rear the young and maintain an underground burrow system. Little is known about the neurobiological basis of the complex sociality exhibited by this species. The neuropeptide oxytocin (Oxt) modulates social bonding and other social behaviors in many vertebrates. Here we examined the distribution of Oxt immunoreactivity in the brains of male and female naked mole-rats. As in other species, the majority of Oxt-immunoreactive (Oxt-ir) cells were found in the paraventricular and supraoptic nuclei, with additional labeled cells scattered throughout the preoptic and anterior hypothalamic areas. Oxt-ir fibers were found traveling toward and through the median eminence, as well as in the tenia tecta, septum, and nucleus of diagonal band of Broca. A moderate network of fibers covered the bed nucleus of the stria terminalis and preoptic area, and a particularly dense fiber innervation of the nucleus accumbens and substantia innominata was observed. In the brainstem, Oxt-ir fibers were found in the periaqueductal grey, locus coeruleus, parabrachial nucleus, nucleus of the solitary tract, and nuclueus ambiguus. The high levels of Oxt immunoreactivity in the nucleus accumbens and preoptic area are intriguing, given the link in other rodents between Oxt signaling in these regions and maternal behavior. Although only the queen gives birth or nurses pups in a naked mole-rat colony, most individuals actively participate in pup care. PMID:18582538

Rosen, Greta J.; de Vries, Geert J.; Goldman, Sharry L.; Goldman, Bruce D.; Forger, Nancy G.

2008-01-01

367

Deep brain stimulation with simultaneous FMRI in rodents.  

PubMed

In order to visualize the global and downstream neuronal responses to deep brain stimulation (DBS) at various targets, we have developed a protocol for using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) to image rodents with simultaneous DBS. DBS fMRI presents a number of technical challenges, including accuracy of electrode implantation, MR artifacts created by the electrode, choice of anesthesia and paralytic to minimize any neuronal effects while simultaneously eliminating animal motion, and maintenance of physiological parameters, deviation from which can confound the BOLD signal. Our laboratory has developed a set of procedures that are capable of overcoming most of these possible issues. For electrical stimulation, a homemade tungsten bipolar microelectrode is used, inserted stereotactically at the stimulation site in the anesthetized subject. In preparation for imaging, rodents are fixed on a plastic headpiece and transferred to the magnet bore. For sedation and paralysis during scanning, a cocktail of dexmedetomidine and pancuronium is continuously infused, along with a minimal dose of isoflurane; this preparation minimizes the BOLD ceiling effect of volatile anesthetics. In this example experiment, stimulation of the subthalamic nucleus (STN) produces BOLD responses which are observed primarily in ipsilateral cortical regions, centered in motor cortex. Simultaneous DBS and fMRI allows the unambiguous modulation of neural circuits dependent on stimulation location and stimulation parameters, and permits observation of neuronal modulations free of regional bias. This technique may be used to explore the downstream effects of modulating neural circuitry at nearly any brain region, with implications for both experimental and clinical DBS. PMID:24561922

Younce, John Robert; Albaugh, Daniel L; Shih, Yen-Yu Ian

2014-01-01

368

Tropical Mesoscale and Local Circulations  

NSDL National Science Digital Library

This interactive module is part of an online university-level tropical synoptic meteorology course, which helps international meteorologists meet basic instructional requirements. In the module, we discuss: Mesoscale, thermally-forced circulations (i.e. land-sea breeze and mountain-valley breeze), including How they are formed and their diurnal cycle Factors that modify thermally forced circulations The weather associated with thermally forced circulations, particularly convection and other significant weather Interactions of mesoscale, thermally forced circulations with other atmospheric phenomena, including Intersection of mesoscale circulations and of mesoscale circulations with convective outflow boundaries Thermally forced circulation interactions with monsoonal and trade wind flows The impact of thermally forced and interacting circulations at various scales on the diurnal cycle of precipitation in the tropics, and A case example from the Lake Victoria basin, showing complex thermally forced circulations, outflow boundaries, and synoptic scale flow.

COMET

2012-11-27

369

Genital manifestations of tropical diseases  

PubMed Central

Genital symptoms in tropical countries and among returned travellers can arise from a variety of bacterial, protozoal, and helminthic infections which are not usually sexually transmitted. The symptoms may mimic classic sexually transmitted infections (STIs) by producing ulceration (for example, amoebiasis, leishmaniasis), wart-like lesions (schistosomiasis), or lesions of the upper genital tract (epididymo-orchitis caused by tuberculosis, leprosy, and brucellosis; salpingitis as a result of tuberculosis, amoebiasis, and schistosomiasis). A variety of other genital symptoms less suggestive of STI are also seen in tropical countries. These include hydrocele (seen with filariasis), which can be no less stigmatising than STI, haemospermia (seen with schistosomiasis), and hypogonadism (which may occur in lepromatous leprosy). This article deals in turn with genital manifestations of filariasis, schistosomiasis, amoebiasis, leishmaniasis, tuberculosis and leprosy and gives clinical presentation, diagnosis, and treatment. PMID:14755029

Richens, J

2004-01-01

370

Tropical Wetlands as Carbon Sinks  

NASA Astrophysics Data System (ADS)

This presentation focuses on the tropical wetlands of sub-Saharan Africa. These are an understudied ecosystem in which large emergent grasses and sedges normally dominate and which have the potential to sequester significant amounts of carbon. Measurements of Net Primary Production of these wetlands show that they are some of the highest values recorded for any ecosystem. We have used eddy covariance to measure Net Ecosystem Exchange of pristine and disturbed wetlands and show that pristine systems can have sink strengths as strong as tropical forests while disturbed systems that have been reclaimed for agricultural purposes have a very much reduced carbon sink activity and may be net carbon sources. The management issues surrounding the use of these wetlands illustrate a direct conflict between the production of food crops for the local population and the maintenance of carbon sequestration as an ecosystem service.

Jones, M. B.; Saunders, M.

2007-12-01

371

Sound localization in a predatory rodent, the northern grasshopper mouse (Onychomys leucogaster).  

PubMed

A comparison of the ability of mammals to localize sound revealed that among the animals examined to date, none of the rodents have been able to localize as accurately as the carnivores. Because all of these rodents are prey animals, the question arises as to whether their poor localization acuity is a phyletic trait of Rodentia or whether it is a trait common to prey species that may be under less selective pressure than predators to localize sound accurately. To answer this question, sound localization acuity was determined in a species that is both predatory and a rodent, the northern grasshopper mouse. Localization thresholds for a single 100-ms noise burst were determined for three grasshopper mice using a conditioned avoidance procedure. Their 50% discrimination threshold of 19 degrees is larger than that of any of the previously tested carnivores and well within the range of other rodents. However, calculations of the binaural sound localization cues available to rodents (based on their head size) suggest that the grasshopper mouse may make more efficient use of the available locus cues than other rodents. Thus, although the grasshopper mouse cannot localize as accurately as carnivores, it appears to be more accurate than predicted for a nonpredatory rodent of its size. PMID:3365945

Heffner, R S; Heffner, H E

1988-03-01

372

Differentiation in seed hoarding among three sympatric rodent species in a warm temperate forest.  

PubMed

Although seed hoarding by rodents has been extensively studied, differentiation in seed-hoarding behaviors among sympatric rodent species has not been well investigated. Using semi-natural enclosures, we demonstrated that three sympatric rodent species showed clear differentiation in food selection, scatter versus larder hoarding behaviors and eating behaviors when offered seeds of four plant species from a warm temperate forest in northern China. The large field mouse Apodemus peninsulae preferred seeds of wild apricot (Prunus armeniaca) and Liaodong oak (Quercus liaotungensis), whereas the Chinese white-bellied rat Niviventor confucianus preferred seeds of cultivated walnut and Liaodong oak, and the David's rock squirrel Sciurotamias davidianus preferred seeds of cultivated walnut, wild apricot and Liaodong oak. All three rodents showed larder hoarding of seeds from all four plant species, but the large field mouse showed scatter hoarding of wild apricot, and the David's rock squirrel showed scatter hoarding of Liaodong oak and wild walnut. Acorns of Liaodong oak, which have a soft seed hull, were more often eaten in situ, whereas wild walnuts, which have a hard seed hull and more tannin, were less hoarded by all rodent species. Differentiation in the scatter versus larder hoarding behaviors of sympatric rodent species suggests that sympatric rodents play different roles in the regeneration of different sympatric plant species. PMID:21396061

Lu, Jiqi; Zhang, Zhibin

2008-06-01

373

Medical geochemistry of tropical environments  

NASA Astrophysics Data System (ADS)

Geochemically, tropical environments are unique. This uniqueness stems from the fact that these terrains are continuously subjected to extreme rainfall and drought with resulting strong geochemical fractionation of elements. This characteristic geochemical partitioning results in either severe depletion of elements or accumulation to toxic levels. In both these situations, the effect on plant, animal and human health is marked. Medical geochemistry involves the study of the relationships between the geochemistry of the environment in which we live and the health of the population living in this particular domain. Interestingly, the relationships between geochemistry and health are most marked in the tropical countries, which coincidentally are among the poorest in the world. The very heavy dependence on the immediate environment for sustainable living in these lands enables the medical geochemist to observe correlations between particular geochemical provinces and the incidence of certain diseases unique to these terrains. The aetiology of diseases such as dental and skeletal fluorosis, iodine deficiency disorders, diseases of humans and animals caused by mineral imbalances among others, lie clearly in the geochemical environment. The study of the chemistry of the soils, water and stream sediments in relation to the incidence of geographically distributed diseases in the tropics has not only opened up new frontiers in multidisciplinary research, but has offered new challenges to the medical profession to seriously focus attention on the emerging field of medical geochemistry with the collaboration of geochemists and epidemiologists.

Dissanayake, C. B.; Chandrajith, Rohana

1999-10-01

374

Rain from Tropical Storm Noel  

NASA Technical Reports Server (NTRS)

Though not the most powerful storm of the 2007 Atlantic Hurricane season, Tropical Storm Noel was among the most deadly. Only Category 5 Hurricane Felix and its associated flooding had a higher toll. The slow-moving Tropical Storm Noel inundated the Dominican Republic, Haiti, Jamaica, Cuba, and the Bahamas with heavy rain between October 28 and November 1, 2007. The resulting floods and mudslides left at least 115 dead and thousands homeless throughout the Caribbean, reported the Associated Press on November 2, 2007. This image shows the distribution of the rainfall that made Noel a deadly storm. The image shows rainfall totals as measured by the Multi-satellite Precipitation Analysis (MPA) at NASA Goddard Space Flight Center from October 26 through November 1, 2007. The analysis is based on measurements taken by the Tropical Rainfall Measuring Mission (TRMM) satellite. The heaviest rainfall fell in the Dominican Republic and the Bahamas, northeast of Noel's center. Areas of dark red show that rainfall totals over the south-central Dominican Republic and parts of the Bahamas were over 551 millimeters (21 inches). Much of eastern Hispaniola, including both the Dominican Republic and Haiti received at least 200 mm (about 8 inches) of rain, shown in yellow. Rainfall totals over Haiti and Cuba were less, with a range of at least 50 mm (2 inches) to over 200 mm (8 inches).

2007-01-01

375

Ecotoxicology of tropical marine ecosystems  

SciTech Connect

The negative effects of chemical contaminants on tropical marine ecosystems are of increasing concern as human populations expand adjacent to these communities. Watershed streams and ground water carry a variety of chemicals from agricultural, industrial, and domestic activities, while winds and currents transport pollutants from atmospheric and oceanic sources to these coastal ecosystems. The implications of the limited information available on impacts of chemical stressors on mangrove forests, seagrass meadows, and coral reefs are discussed in the context of ecosystem management and ecological risk assessment. Three classes of pollutants have received attention: heavy metals, petroleum, and synthetic organics. Heavy metals have been detected in all three ecosystems, causing physiological stress, reduced reproductive success, and outright mortality in associated invertebrates and fishes. Oil spills have been responsible for the destruction of entire coastal shallow-water communities, with recovery requiring years. Herbicides are particularly detrimental to mangroves and seagrasses and adversely affect the animal-algal symbioses in corals. Pesticides interfere with chemical cues responsible for key biological processes, including reproduction and recruitment of a variety of organisms. Information is lacking with regard to long-term recovery, indicator species, and biomarkers for tropical communities. Critical areas that are beginning to be addressed include the development of appropriate benchmarks for risk assessment, baseline monitoring criteria, and effective management strategies to protect tropical marine ecosystems in the face of mounting anthropogenic disturbance.

Peters, E.C. [Tetra Tech, Inc., Fairfax, VA (United States); Gassman, N.J.; Firman, J.C. [Univ. of Miami, FL (United States). Rosenstiel School of Marine and Atmospheric Science; Richmond, R.H. [Univ. of Guam, Mangilao (Guam). Marine Lab.; Power, E.A. [EVS Environment Consultants, Ltd., North Vancouver, British Columbia (Canada)

1997-01-01

376

Camera Trapping: A Contemporary Approach to Monitoring Invasive Rodents in High Conservation Priority Ecosystems  

PubMed Central

Invasive rodent species have established on 80% of the world's islands causing significant damage to island environments. Insular ecosystems support proportionally more biodiversity than comparative mainland areas, highlighting them as critical for global biodiversity conservation. Few techniques currently exist to adequately detect, with high confidence, species that are trap-adverse such as the black rat, Rattus rattus, in high conservation priority areas where multiple non-target species persist. This study investigates the effectiveness of camera trapping for monitoring invasive rodents in high conservation areas, and the influence of habitat features and density of colonial-nesting seabirds on rodent relative activity levels to provide insights into their potential impacts. A total of 276 camera sites were established and left in situ for 8 days. Identified species were recorded in discrete 15 min intervals, referred to as ‘events’. In total, 19 804 events were recorded. From these, 31 species were identified comprising 25 native species and six introduced. Two introduced rodent species were detected: the black rat (90% of sites), and house mouse Mus musculus (56% of sites). Rodent activity of both black rats and house mice were positively associated with the structural density of habitats. Density of seabird burrows was not strongly associated with relative activity levels of rodents, yet rodents were still present in these areas. Camera trapping enabled a large number of rodents to be detected with confidence in site-specific absences and high resolution to quantify relative activity levels. This method enables detection of multiple species simultaneously with low impact (for both target and non-target individuals); an ideal strategy for monitoring trap-adverse invasive rodents in high conservation areas. PMID:24599307

Rendall, Anthony R.; Sutherland, Duncan R.; Cooke, Raylene; White, John

2014-01-01

377

Seed removal by scatter-hoarding rodents: The effects of tannin and nutrient concentration.  

PubMed

The mutualistic interaction between scatter-hoarding rodents and seed plants have a long co-evolutionary history. Plants are believed to have evolved traits that influence the foraging behavior of rodents, thus increasing the probability of seed removal and caching, which benefits the establishment of seedlings. Tannin and nutrient content in seeds are considered among the most essential factors in this plant-animal interaction. However, most previous studies used different species of plant seeds, rendering it difficult to tease apart the relative effect of each single nutrient on rodent foraging behavior due to confounding combinations of nutrient contents across seed species. Hence, to further explore how tannin and different nutritional traits of seed affect scatter-hoarding rodent foraging preferences, we manipulated tannin, fat, protein and starch content levels, and also seed size levels by using an artificial seed system. Our results showed that both tannin and various nutrients significantly affected rodent foraging preferences, but were also strongly affected by seed size. In general, rodents preferred to remove seeds with less tannin. Fat addition could counteract the negative effect of tannin on seed removal by rodents, while the effect of protein addition was weaker. Starch by itself had no effect, but it interacted with tannin in a complex way. Our findings shed light on the effects of tannin and nutrient content on seed removal by scatter-hoarding rodents. We therefore, believe that these and perhaps other seed traits should interactively influence this important plant-rodent interaction. However, how selection operates on seed traits to counterbalance these competing interests/factors merits further study. PMID:25625425

Wang, Bo; Yang, Xiaolan

2015-04-01

378

Detection of Leishmania donovani and L. tropica in Ethiopian wild rodents.  

PubMed

Human visceral (VL, also known as Kala-azar) and cutaneous (CL) leishmaniasis are important infectious diseases affecting countries in East Africa that remain endemic in several regions of Ethiopia. The transmission and epidemiology of the disease is complicated due to the complex life cycle of the parasites and the involvement of various Leishmania spp., sand fly vectors, and reservoir animals besides human hosts. Particularly in East Africa, the role of animals as reservoirs for human VL remains unclear. Isolation of Leishmania donovani parasites from naturally infected rodents has been reported in several endemic countries; however, the status of rodents as reservoirs in Ethiopia remains unclear. Here, we demonstrated natural Leishmania infections in rodents. Animals were trapped in 41 localities of endemic and non-endemic areas in eight geographical regions of Ethiopia and DNA was isolated from spleens of 586 rodents belonging to 21 genera and 38 species. Leishmania infection was evaluated by real-time PCR of kinetoplast (k)DNA and confirmed by sequencing of the PCR products. Subsequently, parasite species identification was confirmed by PCR and DNA sequencing of the 18S ribosomal RNA internal transcribed spacer one (ITS1) gene. Out of fifty (8.2%) rodent specimens positive for Leishmania kDNA-PCR and sequencing, 10 were subsequently identified by sequencing of the ITS1 showing that five belonged to the L. donovani complex and five to L. tropica. Forty nine kDNA-positive rodents were found in the endemic localities of southern and eastern Ethiopia while only one was identified from northwestern Ethiopia. Moreover, all the ten ITS1-positive rodents were captured in areas where human leishmaniasis cases have been reported and potential sand fly vectors occur. Our findings suggest the eco-epidemiological importance of rodents in these foci of leishmaniasis and indicate that rodents are likely to play a role in the transmission of leishmaniasis in Ethiopia, possibly as reservoir hosts. PMID:25700710

Kassahun, Aysheshm; Sadlova, Jovana; Dvorak, Vit; Kostalova, Tatiana; Rohousova, Iva; Frynta, Daniel; Aghova, Tatiana; Yasur-Landau, Daniel; Lemma, Wessenseged; Hailu, Asrat; Baneth, Gad; Warburg, Alon; Volf, Petr; Votypka, Jan

2015-05-01

379

Adaptation of an ICAM-1-Tropic Enterovirus to the Mouse Respiratory Tract?  

PubMed Central

Respiratory tract (RT) infections by members of the enterovirus (EV) genus of the Picornaviridae family are the most frequent cause for the common cold and a major factor in the exacerbation of chronic pulmonary diseases. The lack of a practical small-animal model for these infections has obstructed insight into pathogenic mechanisms of the common cold and their role in chronic RT illness and has hampered preclinical evaluation of antiviral strategies. Despite significant efforts, it has been difficult to devise rodent models that exhibit viral replication in the RT. This is due mainly to well-known intracellular host restrictions of EVs with RT tropism in rodent cells. We report the evolution of variants of the common-cold-causing coxsackievirus A21, an EV with tropism for the human intercellular adhesion molecule 1 (hICAM-1), through serial passage in the lungs of mice transgenic for the hICAM-1 gene. This process was accompanied by multiple changes in the viral genome, suggesting exquisite adaptation of hICAM-1-tropic enteroviruses to the specific growth conditions within the RT. In vivo mouse RT-adapted, variant coxsackievirus A21 exhibited replication competence in the lungs of hICAM-1 transgenic mice, providing a basis for unraveling EV-host interactions in the mouse RT. PMID:21450825

Wang, Eric S.; Dobrikova, Elena; Goetz, Christian; Dufresne, Andrew T.; Gromeier, Matthias

2011-01-01

380

Pathology of Rodent Models of Intestinal Cancer: Progress Report and Recommendations  

PubMed Central

In October 2010, a pathology review of rodent models of intestinal neoplasia was held at The Jackson Laboratory. This review complemented 2 other concurrent events: a workshop on methods of modeling colon cancer in rodents and a conference on current issues in murine and human colon cancer. We summarize the results of the pathology review and the committee’s recommendations for tumor nomenclature. A virtual high-resolution image slide box of these models has been developed. This report discusses significant recent developments in rodent modeling of intestinal neoplasia, including the role of stem cells in cancer and the creation of models of metastatic intestinal cancer. PMID:23415801

Washington, Mary Kay; Powell, Anne E.; Sullivan, Ruth; Sundberg, John; Wright, Nicholas; Coffey, Robert J.; Dove, William F.

2013-01-01

381

A Student Guide to Tropical Forest Conservation  

NSDL National Science Digital Library

This student guide provides an introduction to the types and value of tropical forests, deforestation, the practice of forestry, forestry research, and tropical forestry. The guide shows how modern practices can help stem the tide of forest destruction while continuing to provide valuable products for people. Examples of sustainable forestry are cited, which could be used as models for protecting and managing tropical forests worldwide.

382

Tropical intraseasonal rainfall variability in the CFSR  

Microsoft Academic Search

While large-scale circulation fields from atmospheric reanalyses have been widely used to study the tropical intraseasonal\\u000a variability, rainfall variations from the reanalyses are less focused. Because of the sparseness of in situ observations available\\u000a in the tropics and strong coupling between convection and large-scale circulation, the accuracy of tropical rainfall from\\u000a the reanalyses not only measures the quality of reanalysis

Jiande Wang; Wanqiu Wang; Xiouhua Fu; Kyong-Hwan Seo

2011-01-01

383

Microbial Degradation of Pesticides in Tropical Soils  

Microsoft Academic Search

\\u000a Although their use is at least as essential in tropical as in temperate zones, pesticides remain little studied as regards\\u000a their fate and microbial degradation in tropical soils. To contribute to closing this gap, this review examines to what extent\\u000a results from studies on pesticide microbial degradation in temperate zones can be extrapolated to the tropics. It is concluded\\u000a that

Ziv Arbeli; Cilia L. Fuentes

384

Ectomycorrhizal Associations Function to Maintain Tropical Monodominance  

Microsoft Academic Search

Tropical rain forests are the epicenters of tree diversity. Nonetheless, tropical monodominance should be defined as >60%,\\u000a rather than >50% of the tree species, co-occur in matrices of high-diversity, mixed rain forest. Several alternative mechanisms\\u000a could produce this pattern, but one frequently cited observation is that most tropical monodominant trees form ectomycorrhizal\\u000a (ECM) associations. The majority of other trees in

Krista L. McGuire

385

A TROPICAL GARDEN FLORA, PLANTS CULTIVATED IN THE HAWAIIAN ISLANDS AND OTHER TROPICAL AREAS.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pemberton, R.W. A Tropical Garden Flora, Plants Cultivated in the Hawaiian Islands and Other Tropical Areas. Economic Botany This is an invited book review of an important new reference book on plants cultivated in the tropical and subtropical areas of the world. This is the long awaited update of ...

386

INTER-AMERICAN TROPICAL TUNA COMMISSION COMISIN INTERAMERICANA DEL ATN TROPICAL  

E-print Network

INTER-AMERICAN TROPICAL TUNA COMMISSION COMISIÓN INTERAMERICANA DEL ATÚN TROPICAL 73RD MEETING The Inter-American Tropical Tuna Commission (IATTC): Taking into account the FAO International Plan to evaluate the incidental mortality of seabirds during longline fishing operations for tunas and tuna

387

Diagnostic research into the tropical atmosphere and the role of tropical processes in the general circulation  

Microsoft Academic Search

The structure of tropical disturbances such as easterly waves, tropical cyclones, cyclonic and anticyclonic eddies in the upper trosposphere, squall lines, monsoon depressions, inter-tropospheric cyclones in the Asian monsoon, subtropical cyclones over the oceans, and mesoscale depressions in the Inter-Tropical Convergence Zone is discussed. Use of FGGE data is described.

M. A. Petrossiants; I. G. Sitnikov

1986-01-01

388

Interactions between climate and tropical cyclones  

NASA Astrophysics Data System (ADS)

For the last 50 years, there have been two major thrusts in tropical cyclone research: determining the state of the atmosphere and ocean that is suitable for the formation of tropical storms (the genesis criteria) and short-term forecasting of the track and intensity of storms. Efforts to forecast seasonal storm activity, especially in the North Atlantic Ocean, have been undertaken through empirical means and, more recently, using low-resolution climate models. Climate model results have been exceptionally encouraging suggesting that the tropical cyclogenesis factors are predictable and are part of the large scale tropical circulation. During the last few years, a spate of papers has noted the relationship between changes in sea-surface temperature (SST) and tropical cyclone intensity and frequency. A critical issue is determining to what degree the frequency of hurricanes, as well as their intensity distribution, will change in a warming world. We discuss recent research regarding the interactions of the climate system with tropical cyclones, including the role of climate in determining the genesis of tropical cyclones and the role of tropical cyclones in the heat balance of the planet. Specifically: (i) We re-examine the genesis criteria of tropical cyclones and add two new criteria based on the behavior of waves in a flow varying in longitude and the inertial instability of equatorial flow in a cross-equatorial pressure gradient environment. Tropical cyclones are seen to form where the stretching deformation is negative and where large-scale waves transform into tight smaller and highly energetic scale vortices. We also discuss the tendency for storms to develop and intensify where the near-equatorial flow is inertially unstable. (ii) Tropical cyclones act to cool the tropical oceans by > 1K/year by evaporation of ocean surface water and by entrainment mixing with cooler water from below the mixed layer. We suggest that tropical cyclones are important part of the heat budget of the planet and act as efficient ventilators of the tropical ocean, transporting heat polewards in both the ocean and the atmosphere. We discuss the mechanisms by which hurricanes efficiently transport mass and heat upwards and then polewards and how the vertically mixed heat in the oceans joins the annual cycle of ocean heat transport. We speculate that the near constancy of the global annual number of tropical cyclones is evidence that the heat transport of storms is governed by an integral constraint applying to the heat balance of the planet. With this information, we can speculate on the characteristics of tropical cyclones in a warmer world.

Webster, P. J.

2007-05-01

389

Superficial cutaneous fungal infections in tropical countries.  

PubMed

Superficial fungal infections represent an important cause of morbidity for people worldwide, particularly in the tropics. Fungal infections affect the skin, hair, or the nails, and tend to thrive in the heat and humidity of tropical countries. Because of environmental and cultural factors unique to the tropics, the causative organisms and presentation of these infections may differ from those in industrialized countries. Treatment options include topical and systemic therapy. However, social and socioeconomic factors in developing tropical countries may necessitate different treatment approaches to achieve success. PMID:19889138

Charles, Alix J

2009-01-01

390

The ecology of tropical lakes and rivers  

SciTech Connect

This is self-contained text reviewing tropical limnology. It discusses a number of communities in detail, including plankton, benthic regions, and the water margins. It introduces the characteristic types and assemblies of animals and plants from tropical communities. The measurement and relative magnitude of such quantifiable aspects as abundance, biomass, primary production, secondary production, and decomposition are all outlined, drawing together the diverse threads of freshwater ecology over one of the earth's climatic belts. Deals with use and abuse of water in the tropics and looks at problems of diversity and diversification in tropical waters.

Payne, A.I.

1986-01-01

391

Microbial safety of tropical and sub-tropical fruit. in Volume 1 – General Physiology, Quality and Handling of Tropical and Sub-tropical Fruits, Postharvest Biology & Technology of Tropical and Sub-tropical Fruits  

Technology Transfer Automated Retrieval System (TEKTRAN)

This chapter describes past outbreaks, potential routes of contamination for specific, potential interventions, and operational procedures associated with tropical and sub-tropical fruits. Various pre-harvest sources can result in contamination of fruits; and survival and growth of pathogens on who...

392

book review: Tackling thorny issues in seasonally dry tropical forests  

E-print Network

D.  (2010) Tropical rain forest ecol? ogy, diversity, and tropical forest to one per? son  is  a  seasonal  rain  forest tropical for? est’  formations  as  various  types  of  ‘seasonal  rain  forest’  (

Ghazoul, Jaboury

2012-01-01

393

Seasonally dry tropical forest mammals: Adaptations and seasonal patterns  

E-print Network

Seasonally dry tropical forests have one of the most extreme climates within tropical ecosystems. Mammals that inhabit tropical dry forests must be capable of dealing with high temperatures, low precipitation in the dry season, and large...

Stoner, Kathryn E.; Timm, Robert M.

2011-01-01

394

The Role of the Tropics in Abrupt Climate Changes  

SciTech Connect

Topics addressed include: abrupt climate changes and ocean circulation in the tropics; what controls the ocean thermal structure in the tropics; a permanent El Niño in paleoclimates; the energetics of the tropical ocean.

Fedorov, Alexey [Yale University] [Yale University

2013-12-07

395

Influence of Tropical Tropopause Layer Cooling on Atlantic Hurricane Activity  

E-print Network

Virtually all metrics of Atlantic tropical cyclone activity show substantial increases over the past two decades. It is argued here that cooling near the tropical tropopause and the associated decrease in tropical cyclone ...

Solomon, Susan

396

Chemical-induced atrial thrombosis in NTP rodent studies.  

PubMed

Cardiac thrombosis, one of the causes of sudden death throughout the world, plays a principal role in several cardiovascular diseases, such as myocardial infarction and stroke in humans. Data from studies of induction of chemical thrombosis in rodents help to identify substances in our environment that may contribute to cardiac thrombosis. Results for more than 500 chemicals tested in rodents in 2-year bioassays have been published as Technical Reports of the National Toxicology Program (NTP) http://ntp-server.niehs.nih.gov/index. We evaluated atrial thrombosis induced by these chemical exposures and compared it to similarly induced lesions reported in the literature. Spontaneous rates of cardiac thrombosis were determined for control Fischer 344 rats and B6C3F1 mice: 0% in rats and mice in 90-day studies and, in 2-year studies, 0.7% in both genders of mice, 4% in male rats, and 1% in female rats. Incidences of atrial thrombosis were increased in high-dosed groups involving 13 compounds (incidence rate: 20-100%): 2-butoxyethanol, C.I. Direct Blue 15, bis(2-chloroethoxy)methane, diazoaminobenzene, diethanolamine, 3,3'-dimethoxybenzidine dihydrochloride, hexachloroethane, isobutene, methyleugenol, oxazepam, C.I. Pigment Red 23, C.I. Acid Red 114, and 4,4'-thiobis(6-t-butyl-m-cresol). The main localization of spontaneously occurring and chemically induced thromboses occurred in the left atrium. The literature survey suggested that chemical-induced atrial thrombosis might be closely related to myocardial injury, endothelial injury, circulatory stasis, hypercoagulability, and impaired atrial mechanical activity, such as atrial fibrillation, which could cause stasis of blood within the left atrial appendage, contributing to left atrial thrombosis. Supplementary data referenced in this paper are not printed in this issue of Toxicologic Pathology. They are available as downloadable files at http://taylorandfrancis.metapress.com/openurl.asp?genre=journal&issn=0192-6233. To access them, click on the issue link for 33(5), then select this article. A download option appears at the bottom of this abstract. In order to access the full article online, you must either have an individual subscription or a member subscription accessed through www.toxpath.org. PMID:16048847

Yoshizawa, Katsuhiko; Kissling, Grace E; Johnson, Jo Anne; Clayton, Natasha P; Flagler, Norris D; Nyska, Abraham

2005-01-01

397

Characterizing the dynamic frequency structure of fast oscillations in the rodent hippocampus  

E-print Network

Fast oscillations or “ripples” are found in the local field potential (LFP) of the rodent hippocampus during awake and sleep states. Ripples have been found to correlate with memory related neural processing, however, the ...

Nguyen, David P.

398

Development of and proposed applications for tetrodes in functional mapping of rodent sensorimotor striatum  

E-print Network

The Wilson-McNaughton tetrode preparation for awake, behaving rodents was adapted by a group of investigators for use in dorsolateral striatum. Measures were taken to improve the reliability of reaching the target area in ...

Iyengar, Deepa Radhakrishna, 1972-

2004-01-01

399

Hantavirus and Arenavirus Antibodies in Persons with Occupational Rodent Exposure, North America  

PubMed Central

Rodents are the principal hosts of Sin Nombre virus, 4 other hantaviruses known to cause hantavirus pulmonary syndrome in North America, and the 3 North American arenaviruses. Serum samples from 757 persons who had worked with rodents in North America and handled neotomine or sigmodontine rodents were tested for antibodies against Sin Nombre virus, Whitewater Arroyo virus, Guanarito virus, and lymphocytic choriomeningitis virus. Antibodies against Sin Nombre virus were found in 4 persons, against Whitewater Arroyo virus or Guanarito virus in 2 persons, and against lymphocytic choriomeningitis virus in none. These results suggest that risk for infection with hantaviruses or arenaviruses usually is low in persons whose occupations entail close physical contact with neotomine or sigmodontine rodents in North America. PMID:17553266

Milazzo, Mary Louise; Armstrong, Lori R.; Childs, James E.; Rollin, Pierre E.; Khabbaz, Rima; Peters, C.J.; Ksiazek, Thomas G.

2007-01-01

400

Mutualistic interactions between granivorous heteromyid rodents and a preferred food resource, Indian ricegrass (Achnatherum hymenoides)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Granivorous heteromyid rodent species and Indian ricegrass (Achnatherum hymenoides) are both widely distributed throughout North American deserts. The vast majority (~95%) of Indian ricegrass seedling recruitment occurs from seed clusters cached in shallowly-buried scatterhoards by heteromyids, espe...

401

Methods and modeling for the reduced platen compression of cancellous bone in the rodent proximal tibia  

E-print Network

This study focused on the reduced platen compression (RPC) test of cancellous bone in the rodent proximal tibia. The objective was to improve methods for this mechanical test, specifically in the areas of specimen location, specimen preparation...

Rogers, William Elliott

2002-01-01

402

Insights into relationships among rodent lineages based on mitochondrial genome sequence data  

E-print Network

This dissertation has two major sections. In Chapter II, complete mitochondrial (mt DNA) genome sequences were used to construct a hypothesis for affinities of most major lineages of rodents that arose quickly in the Eocene and were well established...

Frabotta, Laurence John

2006-04-12

403

PREDICTING RODENT CARCINOGENICITY OF HALOGENATED HYDROCARBON BY IN VIVO BIOCHEMICAL PARAMETERS  

EPA Science Inventory

Forty halogenated hydrocarbons of known rodent carcinogenicity (24 carcinogens, 16 noncarcinogens), including many promoters of carcinogenesis, nongenotoxic carcinogens and hepatocarcinogens were selected for study. he effects of these 40 chemicals on four biochemical assays (hep...

404

Helminth parasite spectrum in rodent hosts from bamboo growing areas of Mizoram, North-east India.  

PubMed

In the northeastern state of Mizoram, India the rodent outbreak is periodic and coincides with bamboo (Melocanna baccifera) bloom causing a tremendous destruction to food crops that often results in famine. The present study was undertaken during the bamboo flowering period (2006-2008) to assess the parasite spectrum and load in the bourgeoning rodent population of the affected region. The survey results of the populations of 9 prevalent rodent species revealed that nematodes were the most dominant parasitic group followed by cestodes of the order Cyclophyllidea; however, the trematodes were found to be conspicuously missing. The nematodes harbored by the rodents belonged to the genera: Syphacia, Aspicularis, Trichuris, Rictularia, Capillaria, Trichosomoides, Nippostrongylus, Hepatojarakus and Heterakis, whereas the cestode genera included Hymenolepis, Raillietina and Taenia. Hymenolepis diminuta was the commonly encountered species. Only one acanthocephalan (Moniliformis sp.) could be collected during the entire study. PMID:23129885

Malsawmtluangi, C; Tandon, V

2009-12-01

405

COMPARATIVE MICROARRAY EXPRESSION ANALYSIS OF SELECTED CANCER RELEVANT GENES IN HYPERTENSIVE RESISTANT VERSUS SUSCEPTIBLE RODENT STRAINS  

EPA Science Inventory

Hypertension and cancer are prevalent diseases. Epidemiological studies suggest that hypertension may increase the long term risk of cancer. Identification of resistance and/or susceptibility genes using rodent models could provide important insights into the management and treat...

406

Leishmania species: Detection and identification by nested PCR assay from skin samples of rodent reservoirs  

PubMed Central

Many rodent species act as reservoir hosts of zoonotic cutaneous leishmaniasis in endemic areas. In the present study a simple and reliable assay based on nested PCR was developed for the detection and identification of Leishmania parasites from rodent skin samples. We designed Leishmania-specific primers that successfully amplified ITS regions of Leishmania major, Leishmania gerbilli and Leishmania turanica using nested PCR. Out of 95 field collected Rhombomys opimus, 21 were positive by microscopic examination and 48 by nested PCR. The percentage of gerbils infected with L. major, L. gerbilli and L. turanica was 3.2%, 1.1% and 27.4%, respectively. In 15.8% of the rodents, we found mixed natural infections by L. major and L. turanica, 1.1% by L. major and L. gerbilli, and 2.1% by the three species. We concluded that this method is simple and reliable for detecting and identifying Leishmania species circulating in rodent populations. PMID:20566364

Akhavan, Amir Ahmad; Mirhendi, Hossein; Khamesipour, Ali; Alimohammadian, Mohammad Hossein; Rassi, Yavar; Bates, Paul; Kamhawi, Shaden; Valenzuela, Jesus G.; Arandian, Mohammad Hossein; Abdoli, Hamid; Jalali-zand, Niloufar; Jafari, Reza; Shareghi, Niloufar; Ghanei, Maryam; Yaghoobi-Ershadi, Mohammad Reza

2010-01-01

407

Detection of Toxoplasma gondii by PCR and Mouse Bioassay in Rodents of Ahvaz District, Southwestern Iran  

PubMed Central

Toxoplasma gondii is obligate coccidian zoonotic parasite. Felidae family is definitive and wide ranges of warm-blooded vertebrates are intermediate hosts for the parasite. Rodents are measured as an important source of T. gondii infection for the definitive host. Thus, this study aimed to investigate Toxoplasm infection in rodents of Ahvaz district, southwest of Iran. A total of 100 rodents (73 Rattus norvegicus, 21 Rattus rattus, and 6 Mus musculus) were collected and studied by GRA6PCR and mouse bioassay. The finding indicated that 6 out of 100 (6%) and 2 out of 100 (2%) samples were positive by PCR and mouse bioassay, respectively. The results show notable chronic infection in the rodent and potential transmission of the infection among animal and men in the region. Accordingly, this study recommended investigating of the T. gondii infection in definitive and other intermediate hosts in other points of Khuzestan province, Southwest, Iran. PMID:24605327

Saki, J.; Khademvatan, S.

2014-01-01

408

Statistical sensitivity for detection of spatial and temporal patterns in rodent population densities.  

PubMed Central

A long-term monitoring program begun 1 year after the epidemic of hantavirus pulmonary syndrome in the U.S. Southwest tracked rodent density changes through time and among sites and related these changes to hantavirus infection rates in various small-mammal reservoir species and human disease outbreaks. We assessed the statistical sensitivity of the program's field design and tested for potential biases in population estimates due to unintended deaths of rodents. Analyzing data from two sites in New Mexico from 1994 to 1998, we found that for many species of Peromyscus, Reithrodontomys, Neotoma, Dipodomys, and Perognathus, the monitoring program detected species-specific spatial and temporal differences in rodent densities; trap-related deaths did not significantly affect long-term population estimates. The program also detected a short-term increase in rodent densities in the winter of 1997-98, demonstrating its usefulness in identifying conditions conducive to increased risk for human disease. PMID:10081679

Parmenter, C. A.; Yates, T. L.; Parmenter, R. R.; Dunnum, J. L.

1999-01-01

409

Inverse association between rural environment in infancy and sensitization to rodents in adulthood  

E-print Network

the prevalence of sensitization to allergens in adulthood. Methods: Sensitization to rodents was determined. 2007;98:440­446. INTRODUCTION Epidemiologic studies of the hygiene hypothesis have pri- marily focused

Illinois at Chicago, University of

410

Segment Specification for the Payload Segment of the Reusable Reentry Satellite: Rodent Module Version  

NASA Technical Reports Server (NTRS)

The Reusable Reentry Satellite (RRS) System is composed of the payload segment (PS), vehicle segment (VS), and mission support (MS) segments. This specification establishes the performance, design, development, and test requirements for the RRS Rodent Module (RM).

1991-01-01

411

Adaptation in Rodent Moles and Insectivorous Moles, and the Theory of Convergence  

Microsoft Academic Search

STUDIES in connexion with the life-history of the Orange Free State rodent mole, Cryptomys, brought to light a remarkable degree of adaptation, anatomically and psychologically, to its mode of life in total darkness.

G. Eloff

1951-01-01

412

Two new species of the chewing louse genus Gliricola Mjöberg (Phthiraptera: Gyropidae) from Peruvian rodents  

E-print Network

Two new species of chewing lice (Phthiraptera: Gyropidae) from high-elevation Peruvian rodents are described and illustrated: Gliricola cutkompi from Cuscomys ashaninka Emmons (Abrocomidae) and G. brooksae from Dactylomys ...

Price, Roger D.; Timm, Robert M.

2002-12-01

413

Evidence for rodent-common and species-typical limb and digit use in eating, derived from a comparative analysis of ten rodent species.  

PubMed

Order Rodentia comprises a vast portion of mammalian species (1814 species), which occupy extremely diverse habitats requiring very distinct motor specializations (e.g. burrowing, hopping, climbing, flying and swimming). Although early classification of paw use ability suggests rodents are impoverished relative to primates and make little use of their paws, there have been no systematic investigations of paw use in rodents. The present study was undertaken to describe limb/paw movements in a variety of common rodents. The movements used for handling sunflower seeds and other foods were videorecorded and analyzed in the guinea pig (Cavia porcellus), Mongolian gerbil (Meriones unguiculatus), Syrian hamster (Mesocricetus auratus), laboratory mouse (Mus musculus), laboratory rat (Rattus norvegicus), gray squirrel (Sciurus carolinensis), red squirrel (Tamiasciurus hudsonicus), Richardson's ground squirrel (Spermophilus richardsonni), prairie dog (Cynomus parvidens), and Canadian beaver (Castor americanus). The results suggested five order-common movements of food handling: (1) locating food by sniffing, (2) grasping food by mouth, (3) sitting back on the haunches to eat, (4) grasping the food using an elbow-in movement, and (5) manipulate the food with the digits. Different species displayed species-typical specializations including (1) bilateral grasping with the paws (gerbil), (2) unilateral grasping with a paw (beaver), (3) unilateral holding (ground squirrels), (4) various grip and digit postures (all species), (5) unilateral object removal from the mouth (gerbil), (6) bilateral thumb holding (squirrels), and (7) simultaneous holding/manipulation of two objects (squirrels). Only the guinea pig did not handle food with its paws, suggesting its behavior is regressive. The existence of a core pattern of paw and digit use in rodents suggests that skilled limb and paw movements originate at least with the common ancestors of the rodent, and likely the common ancestor to rodent and primate lineages, while species-typical movements suggest specialization/regression of limb use has occurred in a number of mammalian orders. PMID:9821545

Whishaw, I Q; Sarna, J R; Pellis, S M

1998-11-01

414

Distinct Leishmania Species Infecting Wild Caviomorph Rodents (Rodentia: Hystricognathi) from Brazil  

PubMed Central

Background Caviomorph rodents, some of the oldest Leishmania spp. hosts, are widely dispersed in Brazil. Despite both experimental and field studies having suggested that these rodents are potential reservoirs of Leishmania parasites, not more than 88 specimens were analyzed in the few studies of natural infection. Our hypothesis was that caviomorph rodents are inserted in the transmission cycles of Leishmania in different regions, more so than is currently recognized. Methodology We investigated the Leishmania infection in spleen fragments of 373 caviomorph rodents from 20 different species collected in five Brazilian biomes in a period of 13 years. PCR reactions targeting kDNA of Leishmania sp. were used to diagnose infection, while Leishmania species identification was performed by DNA sequencing of the amplified products obtained in the HSP70 (234) targeting. Serology by IFAT was performed on the available serum of these rodents. Principal findings In 13 caviomorph rodents, DNA sequencing analyses allowed the identification of 4 species of the subgenus L. (Viannia): L. shawi, L. guyanensis, L. naiffi, and L. braziliensis; and 1 species of the subgenus L. (Leishmania): L. infantum. These include the description of parasite species in areas not previously included in their known distribution: L. shawi in Thrichomys inermis from Northeastern Brazil and L. naiffi in T. fosteri from Western Brazil. From the four other positive rodents, two were positive for HSP70 (234) targeting but did not generate sequences that enabled the species identification, and another two were positive only in kDNA targeting. Conclusions/Significance The infection rate demonstrated by the serology (51.3%) points out that the natural Leishmania infection in caviomorph rodents is much higher than that observed in the molecular diagnosis (4.6%), highlighting that, in terms of the host species responsible for maintaining Leishmania species in the wild, our current knowledge represents only the “tip of the iceberg.” PMID:25503973

Cássia-Pires, Renata; Boité, Mariana C.; D'Andrea, Paulo S.; Herrera, Heitor M.; Cupolillo, Elisa; Jansen, Ana Maria; Roque, André Luiz R.

2014-01-01

415

Behavioral aspects of competition in a three-species rodent guild of coastal southern California  

Microsoft Academic Search

The influence of vole cycles on the demography, spatial organization, and abundance of potential rodent competitors was studied in three California rodents in the laboratory and in the field. Population densities ofMicrotus californicus were inversely correlated with reproductive success in two potential competitors (Reithrodontomys megalotis andMus musculus). Additionally, high-density vole populations forced these species into suboptimal habitats. During low-density vole

Andrew R. Blaustein

1980-01-01

416

Minimally Invasive Method of Determining Blood Input Function from PET Images in Rodents  

Microsoft Academic Search

For cardiovascular research on rodents, small-animal PET has limitations because of the inherent spatial resolution of the sys- tem and because of cardiac motion. A factor analysis (FA) tech- nique for extracting the blood input function and myocardial time-activity curve from dynamic small-animal PET images of the rodent heart has been implemented to overcome these limi- tations. Methods: Six Sprague-Dawley

Joonyoung Kim; Pilar Herrero; Terry Sharp; Richard Laforest; Douglas J. Rowland; Yuan-Chuan Tai; Jason S. Lewis; Michael J. Welch

2006-01-01

417

Genome dynamics of Bartonella grahamii in micro-populations of woodland rodents  

Microsoft Academic Search

BACKGROUND: Rodents represent a high-risk reservoir for the emergence of new human pathogens. The recent completion of the 2.3 Mb genome of Bartonella grahamii, one of the most prevalent blood-borne bacteria in wild rodents, revealed a higher abundance of genes for host-cell interaction systems than in the genomes of closely related human pathogens. The sequence variability within the global B.

Eva C Berglund; Christian Ehrenborg; Olga Vinnere Pettersson; Fredrik Granberg; Kristina Näslund; Martin Holmberg; Siv GE Andersson

2010-01-01

418

Patterns of Rodent Abundance on Open-Space Grasslands in Relation to Suburban Edges  

Microsoft Academic Search

Relatively little is known about the response of grassland rodent populations to urban and subur- ban edges. We live-trapped rodents for three summers on 65 3.1-ha grassland plots on open space of the city of Boulder, Colorado, and compared capture rates among species according to habitat type, percentage of the 40 ha surrounding each plot that was suburbanized, and proximity

Carl E. Bock; Kerri T. Vierling; Sandra L. Haire; John D. Boone; William W. Merkle

2002-01-01

419

Early miocene rodents from the Aktau Mountains (South-Eastern Kazakhstan)  

Microsoft Academic Search

The rodent assemblage from the Middle Members of the Chul’adyr Formation contains seven species that belong to six (sub)families.\\u000a The dominant Cricetidae are represented by a new genus and species:Aktaumys dzhungaricus and by a new species ofKarydomys: K. dzerzhinskii. Each of the other rodent species: ?Sinosminthus gen. et sp. indet.,Sayimys aff.obliquidens, Asiacastor aff.baschanovi and Tachyoryctoidinae gen. A, sp. 1, is

Elena G. Kordikova; Hans de Bruijn

2001-01-01

420

Natural Host Relationships and Genetic Diversity of Rodent-Associated Hantaviruses in Southeastern Brazil  

Microsoft Academic Search

Objective: Hantaviruses are rodent-borne RNA viruses that have caused hantavirus cardiopulmonary syndrome in several Brazilian regions. In the present study, geographical distribution, seroprevalence, natural host range, and phylogenetic relations of rodent-associated hantaviruses collected from seven counties of Southeastern Brazil were evaluated. Methods: ELISA, RT-PCR and phylogenetic analysis were used in this study. Results: Antibodies to hantavirus were detected in Bolomys

Ricardo Luiz Moro de Sousa; Marcos Lázaro Moreli; Alessandra Abel Borges; Gelse Mazzoni Campos; Márcia Cristina Livonesi; Luiz Tadeu Moraes Figueiredo; Aramis Augusto Pinto

2008-01-01

421

Characterization of spontaneous and chemically induced cardiac lesions in rodent model systems  

Microsoft Academic Search

Induction of heart disease can be related to exposure to a number of agents, including environmental chemicals. Studies with\\u000a laboratory rodents are commonly use to identify cardiotoxic agents and to investigate mechanisms of toxicity. This study was\\u000a conducted to characterize spontaneous and chemically-induced rodent heart lesions. A retrospective light-microscopic evaluation\\u000a was performed on the hearts of F344 rats and B6C3F1

Micheal P. Jokinen; Warren G. Lieuallen; Crystal L. Johnson; June Dunnick; Abraham Nyska

2005-01-01

422

Does weather shape rodents? Climate related changes in morphology of two heteromyid species  

Microsoft Academic Search

Geographical variation in morphometric characters in heteromyid rodents has often correlated with climate gradients. Here,\\u000a we used the long-term database of rodents trapped in the Sevilleta National Wildlife Refuge in New Mexico, USA to test whether\\u000a significant annual changes in external morphometric characters are observed in a region with large variations in temperature\\u000a and precipitation. We looked at the relationships

Mosheh Wolf; Michael Friggens; Jorge Salazar-Bravo

2009-01-01

423

The modified hole board as a differential screen for behavior in rodents  

Microsoft Academic Search

We describe a modified hole board (mHB) paradigm as a test for unconditioned behavior in rodents that is aimed at analyzing\\u000a a variety of behavioral dimensions. We demonstrate that the mHB enables the investigation of different behavioral dimensions\\u000a in rodents in only one test by reproducing the behavioral characteristics previously collected from multiple behavioral tests\\u000a in rats bred for either

F. Ohl; F. Holsboer; R. Landgraf

2001-01-01

424

Wide Distribution and Genetic Diversity of “Candidatus Neoehrlichia mikurensis” in Rodents from China  

PubMed Central

“Candidatus Neoehrlichia mikurensis” was detected by PCR in 4.0% (34/841) of the rodents tested in this study. The 34 rodents represented nine species from seven regions of China. Phylogenetic analyses based on the partial groEL and nearly entire 16S rRNA gene sequences of the agent revealed genetic diversity, which was correlated with its geographic origins. PMID:23183973

Li, Hao; Jiang, Jiafu; Tang, Fang; Sun, Yi; Li, Zengde; Zhang, Weilong; Gong, Zhengda; Liu, Kun; Yang, Hong

2013-01-01

425

The Mighty Mouse: The Impact of Rodents on Advances in Biomedical Research  

PubMed Central

Mice and rats have long served as the preferred species for biomedical research animal models due to their anatomical, physiological, and genetic similarity to humans. Advantages of rodents include their small size, ease of maintenance, short life cycle, and abundant genetic resources. The Rat Resource and Research Center (RRRC) and the MU Mutant Mouse Regional Resource Center (MMRRC) serve as centralized repositories for the preservation and distribution of the ever increasing number of rodent models. PMID:23829104

Bryda, Elizabeth C.

2014-01-01

426

Two-phase seed dispersal: linking the effects of frugivorous birds and seed-caching rodents  

Microsoft Academic Search

Frugivorous birds disperse the seeds of many fruit-bearing plants, but the fate of seeds after defecation or regurgitation\\u000a is often unknown. Some rodents gather and scatter hoard seeds, and some of these may be overlooked, germinate, and establish\\u000a plants. We show that these two disparate modes of seed dispersal are linked in some plants. Rodents removed large (>25 mg)\\u000a seeds from

Stephen B. Vander Wall; Kellie M. Kuhn; Jennifer R. Gworek

2005-01-01

427

Chemical cues used by prairie rattlesnakes (Crotalus viridis) to follow trails of rodent prey.  

PubMed

Each of 10 prairie rattlesnakes (Crotalus viridis) was exposed to three types of trails after striking rodent prey (Mus musculus). One trail was made with mouse urine, another was made with tap water, and the third consisted of materials from mouse integument. The snakes exhibited trailing behavior only when integumentary trails were available. It was concluded that prairie rattlesnakes do not utilize urinary cues; instead they attend to materials associated with rodent skin and fur. PMID:24264897

Chiszar, D; Melcer, T; Lee, R; Radcliffe, C W; Duvall, D

1990-01-01

428

Methane Emission from Tropical Rivers  

NASA Astrophysics Data System (ADS)

Inland water is already known as an important source of methane to atmosphere. Methane is produced in anaerobic environments usually find in lakes and floodplain bottom sediment. It is the main reason that almost all information regarding methane flux come from this environments. However, while floodplain dries during low water season reducing methanogenesis, rivers keep the capacity to emit methane throughout the year. Here we present preliminary results of CH4 flux measurements done in 6 large tropical rivers within the Amazon basin. We measured 17 areas using floating chamber during dry (low water) season, between September and November of 2011, in Amazon river mainstem, Araguaia, Xingu, Tapajós, Madeira, and Negro Rivers. Measured fluxes of all rivers ranged from 59.3 to 2974.4 mmol m-2 yr-1. Geomorphologic structure of channels is one important factor that contributes to this high heterogeneity due to development of low flow velocity depositional settings allowing formation of anoxic zones in rivers. Hydraulic and sediment barriers in the confluence of river channels promote the generation of natural dams which function as a trap for the suspension load favoring the deposition of organic rich muds. This kind of environment is very different from common river channels and has a stronger potential of methane emission. Average values of our flux measurements for this two river environments show that depositional areas can have much higher fluxes than the main channel, 1089.6 and 163.1 mmol m-2 yr-1, respectively. Hence, CH4 flux from these depositional zones is similar to some tropical floodplain lakes and reservoirs. Although the low flux from channel, the area covered by water is very large resulting in a significant contribution to the regional methane emission to the atmosphere. Moreover, mapping the area of these depositional river zones will give us a better idea of the magnitude of methane flux from tropical rivers.

Sawakuchi, H. O.; Rasera, M. F. F. L.; Krusche, A. V.; Ballester, M. V. R.

2012-04-01

429

Traumatic Brain Injury – Modeling Neuropsychiatric Symptoms in Rodents  

PubMed Central

Each year in the US, ?1.5 million people sustain a traumatic brain injury (TBI). Victims of TBI can suffer from chronic post-TBI symptoms, such as sensory and motor deficits, cognitive impairments including problems with memory, learning, and attention, and neuropsychiatric symptoms such as depression, anxiety, irritability, aggression, and suicidal rumination. Although partially associated with the site and severity of injury, the biological mechanisms associated with many of these symptoms – and why some patients experience differing assortments of persistent maladies – are largely unknown. The use of animal models is a promising strategy for elucidation of the mechanisms of impairment and treatment, and learning, memory, sensory, and motor tests have widespread utility in rodent models of TBI and psychopharmacology. Comparatively, behavioral tests for the evaluation of neuropsychiatric symptomatology are rarely employed in animal models of TBI and, as determined in this review, the results have been inconsistent. Animal behavioral studies contribute to the understanding of the biological mechanisms by which TBI is associated with neurobehavioral symptoms and offer a powerful means for pre-clinical treatment validation. Therefore, further exploration of the utility of animal behavioral tests for the study of injury mechanisms and therapeutic strategies for the alleviation of emotional symptoms are relevant and essential. PMID:24109476

Malkesman, Oz; Tucker, Laura B.; Ozl, Jessica; McCabe, Joseph T.

2013-01-01

430

Effect of predation risk on selectivity in heteromyid rodents.  

PubMed

Variations in predation risk affect the costs of foraging and may therefore warrant different foraging decisions. One class of models ("higher requisite profit") predicts that foragers should become more selective when predation risk increases, as low-profitability items that do not cover the increased costs are dropped from the diet. An alternative class of models ("reduced finickiness") predicts that foragers should become less selective when predation risk increases, because selectivity requires more extensive assessment and/or search behaviour, prolonging exposure to risk. We assessed the selectivity of foraging heteromyid rodents (Merriam's kangaroo rats, Dipodomys merriami, and pocket mice, Chaetodipus spp.) by comparing differences in "giving up densities" (GUD: the quantity of cryptic food left in a patch by animals for whom the diminishing marginal gains from foraging have dropped below the threshold for continued search) for foods of different value as a measure of selectivity in patches varying in predation risk. Data collected over two field seasons revealed that heteromyids were more selective when predation risk was highest; away from the protective cover of shrubs during the full moon. These findings support the predictions of higher requisite profit models. PMID:12914997

Leaver, Lisa A.; Daly, Martin

2003-08-29

431

What Can We Learn from Rodents about Prolactin in Humans?  

PubMed Central

Prolactin (PRL) is a 23-kDa protein hormone that binds to a single-span membrane receptor, a member of the cytokine receptor superfamily, and exerts its action via several interacting signaling pathways. PRL is a multifunctional hormone that affects multiple reproductive and metabolic functions and is also involved in tumorigenicity. In addition to being a classical pituitary hormone, PRL in humans is produced by many tissues throughout the body where it acts as a cytokine. The objective of this review is to compare and contrast multiple aspects of PRL, from structure to regulation, and from physiology to pathology in rats, mice, and humans. At each juncture, questions are raised whether, or to what extent, data from rodents are relevant to PRL homeostasis in humans. Most current knowledge on PRL has been obtained from studies with rats and, more recently, from the use of transgenic mice. Although this information is indispensable for understanding PRL in human health and disease, there is sufficient disparity in the control of the production, distribution, and physiological functions of PRL among these species to warrant careful and judicial extrapolation to humans. PMID:18057139

Ben-Jonathan, Nira; LaPensee, Christopher R.; LaPensee, Elizabeth W.

2008-01-01

432

Dependence Potential of Quetiapine: Behavioral Pharmacology in Rodents  

PubMed Central

Quetiapine is an atypical or second-generation antipsychotic agent and has been a subject of a series of case report and suggested to have the potential for misuse or abuse. However, it is not a controlled substance and is not generally considered addictive. In this study, we examined quetiapine’s dependence potential and abuse liability through animal behavioral tests using rodents to study the mechanism of quetiapine. Molecular biology techniques were also used to find out the action mechanisms of the drug. In the animal behavioral tests, quetiapine did not show any positive effect on the experimental animals in the climbing, jumping, and conditioned place preference tests. However, in the head twitch and self-administration tests, the experimental animals showed significant positive responses. In addition, the action mechanism of quetiapine was found being related to dopamine and serotonin release. These results demonstrate that quetiapine affects the neurological systems related to abuse liability and has the potential to lead psychological dependence, as well. PMID:24244816

Cha, Hye Jin; Lee, Hyun-A; Ahn, Joon-Ik; Jeon, Seol-Hee; Kim, Eun Jung; Jeong, Ho-Sang

2013-01-01

433

Use of rodents as models of human diseases  

PubMed Central

Advances in molecular biology have significantly increased the understanding of the biology of different diseases. However, these discoveries have not yet been fully translated into improved treatments for patients with diseases such as cancers. One of the factors limiting the translation of knowledge from preclinical studies to the clinic has been the limitations of in vivo diseases models. In this brief review, we will discuss the advantages and disadvantages of rodent models that have been developed to simulate human pathologies, focusing in models that employ xenografts and genetic modification. Within the framework of genetically engineered mouse (GEM) models, we will review some of the current genetic strategies for modeling diseases in the mouse and the preclinical studies that have already been undertaken. We will also discuss how recent improvements in imaging technologies may increase the information derived from using these GEMs during early assessments of potential therapeutic pathways. Furthermore, it is interesting to note that one of the values of using a mouse model is the very rapid turnover rate of the animal, going through the process of birth to death in a very short timeframe relative to that of larger mammalian species. PMID:24459397

Vandamme, Thierry F.

2014-01-01

434

Near-infrared light penetration profile in the rodent brain  

PubMed Central

Abstract. Near-infrared (NIR) lasers find applications in neuro-medicine both for diagnostic and treatment purposes. Penetration depth and profile into neural tissue are critical parameters to be considered in these applications. Published data on the optical properties of rodent neural tissue are rare, despite the frequent use of rats as an animal model. The aim of this study was to measure the light intensity profile inside the rat brain using a direct method, while the medium is being illuminated by an NIR laser beam, and compare the results with in vitro measurements of transmittance in the rat brain slices. The intensity profile along the vertical axis had an exponential decline with multiple regions that could be approximated with different coefficients. The Monte Carlo method that was used to simulate light–tissue interactions and predict the scattering coefficient of brain tissue from the measurements suggested that more scattering occurred in deeper layers of the cortex. A single scattering coefficient of 125??cm?1 was estimated for cortical layers from 300 to 1500 ?m and a gradually increasing value from 125 to 370??cm?1 for depths of 1500 to 3000 ?m. The deviations of in vivo results from the in vitro transmittance measurements, as well as the postmortem in vivo results from the alive measurements were significant. PMID:23831713

Abdo, Ammar; Ersen, Ali; Sahin, Mesut

2013-01-01

435

Rodents and Leptospira transmission risk in Terceira island (Azores).  

PubMed

The role of rodents as Leptospira renal carriers in Terceira island was evaluated (1993-1995) through kidney culture and serology [microscopic aglutination test (MAT)] of 94 mice and rats. Fifty-nine animals were positive (n = 41 by serology + culturing; n = 11 serology; n = 7 culturing), presenting a wide distribution in man-made and natural areas. House mice had the highest bacteriological (82.9%) and serological (90.9%) rates, being strictly related to serovar arborea. Black rats were involved in the dispersion of all isolated L. interrogans sensu lato serovars (arborea, copenhageni and icterohaemorrhagiae). Logistic regression analysis and non-metric multi-dimensional scaling, relating Leptospira infection with biological and environmental variables, expressed that adult males Mus domesticus, sexually active and living in humid biotopes, mainly above 500 m, are the most likely reservoirs. This study emphasizes the role of house-mice in the epidemiology of leptospirosis in Terceira and the need of reducing the risk of Leptospira transmission through integrated control programmes, primarily focusing on adult house-mice in peri-domestic environments, before the breeding season. PMID:11484805

Collares-Pereira, M; Mathias, M L; Santos-Reis, M; Ramalhinho, M G; Duarte-Rodrigues, P

2000-01-01

436

Sexual Differentiation of the Rodent Brain: Dogma and Beyond  

PubMed Central

Steroid hormones of gonadal origin act on the neonatal brain to produce sex differences that underlie adult reproductive physiology and behavior. Neuronal sex differences occur on a variety of levels, including differences in regional volume and/or cell number, morphology, physiology, molecular signaling, and gene expression. In the rodent, many of these sex differences are determined by steroid hormones, particularly estradiol, and are established by diverse downstream effects. One brain region that is potently organized by estradiol is the preoptic area (POA), a region critically involved in many behaviors that show sex differences, including copulatory and maternal behaviors. This review focuses on the POA as a case study exemplifying the depth and breadth of our knowledge as well as the gaps in understanding the mechanisms through which gonadal hormones produce lasting neural and behavioral sex differences. In the POA, multiple cell types, including neurons, astrocytes, and microglia are masculinized by estradiol. Multiple downstream molecular mediators are involved, including prostaglandins, various glutamate receptors, protein kinase A, and several immune signaling molecules. Moreover, emerging evidence indicates epigenetic mechanisms maintain sex differences in the POA that are organized perinatally and thereby produce permanent behavioral changes. We also review emerging strategies to better elucidate the mechanisms through which genetics and epigenetics contribute to brain and behavioral sex differences. PMID:22363256

Lenz, Kathryn M.; Nugent, Bridget M.; McCarthy, Margaret M.

2012-01-01

437

Purification of pericytes from rodent optic nerve by immunopanning.  

PubMed

This protocol describes the use of immunopanning to purify rodent pericytes from the optic nerve. Immunopanning permits the prospective isolation of pericytes from optic nerve tissue by relying on the binding of pericytes to an anti-PDGFR? (platelet-derived growth factor receptor beta) antibody adhered to a Petri dish. The cells are viable at the end of this gentle procedure, and they can be analyzed acutely for gene expression or cultured alone or in coculture with other central nervous system (CNS) cell types, including CNS endothelial cells and CNS astrocytes. As written, this procedure is used for isolation of optic nerve pericytes from the rat. The same PDGFR? antibodies can be used for purifying optic nerve pericytes from the mouse, but alternate negative panning antibodies must be used to ensure that astrocytes do not contaminate the preparation. This procedure can also be modified to purify pericytes from the brain. The same PDGFR? antibody is used, but additional steps (specific dissections or negative panning) are required to ensure that other PDGFR?-positive contaminants, including cells from the rostral migratory stream, are depleted from the cell suspension. PMID:24890207

Zhou, Lu; Sohet, Fabien; Daneman, Richard

2014-06-01

438

A new gustometer for taste testing in rodents.  

PubMed

In recent years, to circumvent the interpretive limitations associated with intake tests commonly used to assess taste function in rodents, investigators have developed devices called gustometers to deliver small volumes of taste samples and measure immediate responses, thereby increasing confidence that the behavior of the animal is under orosensory control. Most of these gustometers can be used to measure unconditioned licking behavior to stimuli presented for short durations and/or can be used to train the animal to respond to various fluid stimuli differentially so as to obtain a reward and/or avoid punishment. Psychometric sensitivity and discrimination functions can thus be derived. Here, we describe a new gustometer design, successfully used in behavioral experiments, that was guided by our experience with an older version used for over 2 decades. The new computer-controlled gustometer features no dead space in stimulus delivery lines, effective cleaning of the licking substrate, and the ability to measure licking without passing electrical current through the animal. The parts and dimensions are detailed, and the benefits and limitations of certain design features are discussed. Schematics for key circuits are provided as supplemental information. Accordingly, it should be possible to fabricate this device in a fashion customized for one's needs. PMID:25616763

Spector, Alan C; Blonde, Ginger D; Henderson, Ross P; Treesukosol, Yada; Hendrick, Paul; Newsome, Ryan; Fletcher, Fred H; Tang, Te; Donaldson, James A

2015-03-01

439

In vivo Optogenetic Stimulation of the Rodent Central Nervous System.  

PubMed

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the neural circuitry governing complex behavioral states. Optogenetics is a cutting-edge tool that is revolutionizing the field of neuroscience and represents one of the first systematic approaches to enable causal testing regarding the relation between neural signaling events and behavior. By combining optical and genetic approaches, neural signaling can be bi-directionally controlled through expression of light-sensitive ion channels (opsins) in mammalian cells. The current protocol describes delivery of specific wavelengths of light to opsin-expressing cells in deep brain structures of awake, freely-moving rodents for neural circuit modulation. Theoretical principles of light transmission as an experimental consideration are discussed in the context of performing in vivo optogenetic stimulation. The protocol details the design and construction of both simple and complex laser configurations and describes tethering strategies to permit simultaneous stimulation of multiple animals for high-throughput behavioral testing. PMID:25651158

Sidor, Michelle M; Davidson, Thomas J; Tye, Kay M; Warden, Melissa R; Diesseroth, Karl; McClung, Colleen A

2015-01-01

440

OCT-aided anastomosis platform study in the rodent model  

NASA Astrophysics Data System (ADS)

Anastomosis is one of the most commonly performed procedure in the clinical environment that involves tubular structures, such as blood vessel, lymphatic vessel, seminal duct and ureter. Suture based anastomosis is still the foundation for most basic surgical training and clinical operation, although alternate techniques have been developed and under development. For those tubular-structure-anastomosis, immediate real-time post-operative evaluation of the surgical outcome is critical to the success of surgery. Previously evaluation is mostly based on surgeons' experience. Fourier-domain optical coherence tomography is high-speed, high-resolution noninvasive 3D imaging modality that has been widely used in the biomedical research and clinical study. In this study we used Fourier-domain optical coherence tomography as an evaluation tool for anastomosis of lymphatic vessels, ureter and seminal duct in rodent model. Immediate post-operative and long term surgical site data were collected and analyzed. Critical clinical parameters such as lumen patency, anastomosed site narrowing and suture error detection are provided to surgeons.

Huang, Yong; Tong, Dedi; Zhu, Shan; Wu, Lehao; Ibrahim, Zuhaib; Lee, WP Andrew; Brandacher, Gerald; Kang, Jin U.

2014-02-01

441

Rodent Herpesvirus Peru Encodes a Secreted Chemokine Decoy Receptor  

PubMed Central

Viruses have long been studied not only for their pathology and associated disease but also as model systems for understanding cellular and immunological processes. Rodent herpesvirus Peru (RHVP) is a recently characterized rhadinovirus related to murine gammaherpesvirus 68 (MHV68) and Kaposi's sarcoma-associated herpesvirus (KSHV) that establishes acute and latent infection in laboratory mice. RHVP encodes numerous unique proteins that we hypothesize might facilitate host immune evasion during infection. We report here that open reading frame (ORF) R17 encodes a high-affinity chemokine binding protein that broadly recognizes human and murine CC and C chemokines. The interaction of R17 with chemokines is generally characterized by rapid association kinetics, and in the case of CCL3, CCL4, CCL5, CCL24, and XCL1, extremely stable complexes are formed. Functionally, R17 potently inhibited CCL2-driven chemotaxis of the human monocytic cell line THP-1, CCL3-driven chemotaxis of peripheral blood mononuclear cells, and CCL2-mediated calcium flux. Our studies also reveal that R17 binds to glycosaminoglycans (GAGs) in a process dependent upon two BBXB motifs and that chemokine and GAG binding can occur simultaneously at distinct sites. Collectively, these studies suggest that R17 may play a role in RHVP immune evasion through the targeted sabotage of chemokine-mediated immune surveillance. PMID:24173234

Lubman, Olga Y.; Cella, Marina; Wang, Xinxin; Monte, Kristen; Lenschow, Deborah J.; Huang, Yina H.

2014-01-01

442

The Behavioral Actions of Lithium in Rodent Models  

PubMed Central

For nearly as long as lithium has been in clinical use for the treatment of bipolar disorder, depression, and other conditions, investigators have attempted to characterize its effects on behaviors in rodents. Lithium consistently decreases exploratory activity, rearing, aggression, and amphetamine-induced hyperlocomotion; and it increases the sensitivity to pilocarpine-induced seizures, decreases immobility time in the forced swim test, and attenuates reserpine-induced hypolocomotion. Lithium also predictably induces conditioned taste aversion and alterations in circadian rhythms. The modulation of stereotypy, sensitization, and reward behavior are less consistent actions of the drug. These behavioral models may be relevant to human symptoms and to clinical endophenotypes. It is likely that the actions of lithium in a subset of these animal models are related to the therapeutic efficacy, as well the side effects, of the drug. We conclude with a brief discussion of various molecular mechanisms by which these lithium-sensitive behaviors may be mediated, and comment on the ways in which rat and mouse models can be used more effectively in the future to address persistent questions about the therapeutically relevant molecular actions of lithium. PMID:17532044

O’Donnell, Kelley C.; Gould, Todd D.

2007-01-01

443

Evolving communicative complexity: insights from rodents and beyond.  

PubMed

Social living goes hand in hand with communication, but the details of this relationship are rarely simple. Complex communication may be described by attributes as diverse as a species' entire repertoire, signallers' individualistic signatures, or complex acoustic phenomena within single calls. Similarly, attributes of social complexity are diverse and may include group size, social role diversity, or networks of interactions and relationships. How these different attributes of social and communicative complexity co-evolve is an active question in behavioural ecology. Sciurid rodents (ground squirrels, prairie dogs and marmots) provide an excellent model system for studying these questions. Sciurid studies have found that demographic role complexity predicts alarm call repertoire size, while social group size predicts alarm call individuality. Along with other taxa, sciurids reveal an important insight: different attributes of sociality are linked to different attributes of communication. By breaking social and communicative complexity down to different attributes, focused studies can better untangle the underlying evolutionary relationships and move us closer to a comprehensive theory of how sociality and communication evolve. PMID:22641825

Pollard, Kimberly A; Blumstein, Daniel T

2012-07-01

444

Development of contrast-enhanced rodent imaging using functional CT  

NASA Astrophysics Data System (ADS)

Micro-computed tomography (microCT) is capable of obtaining high-resolution images of skeletal tissues. However its image contrast among soft tissues remains inadequate for tumor detection. High speed functional computed tomography will be needed to image tumors by employing x-ray contrast medium. The functional microCT development will not only facilitate the image contrast enhancement among different tissues but also provide information of tumor physiology. To demonstrate the feasibility of functional CT in mouse imaging, sequential computed tomography is performed in mice after contrast material administration using a high-speed clinical CT scanner. Although the resolution of the clinical scanner is not sufficient to dissolve the anatomic details of rodents, bulky physiological parameters in major organs such as liver, kidney, pancreas, and ovaries (testicular) can be examined. For data analysis, a two-compartmental model is employed and implemented to characterize the tissue physiological parameters (regional blood flow, capillary permeability, and relative compartment volumes.) The measured contrast dynamics in kidneys are fitted with the compartmental model to derive the kidney tissue physiology. The study result suggests that it is feasible to extract mouse tissue physiology using functional CT imaging technology.

Liang, Yun; Stantz, Keith M.; Krishnamurthi, Ganapathy; Steinmetz, Rosemary; Hutchins, Gary D.

2003-05-01

445

WNT signaling underlies the pathogenesis of neuropathic pain in rodents  

PubMed Central

Treating neuropathic pain is a major clinical challenge, and the underlying mechanisms of neuropathic pain remain elusive. We hypothesized that neuropathic pain–inducing nerve injury may elicit neuronal alterations that recapitulate events that occur during development. Here, we report that WNT signaling, which is important in developmental processes of the nervous system, plays a critical role in neuropathic pain after sciatic nerve injury and bone cancer in rodents. Nerve injury and bone cancer caused a rapid-onset and long-lasting expression of WNTs, as well as activation of WNT/frizzled/?-catenin signaling in the primary sensory neurons, the spinal dorsal horn neurons, and astrocytes. Spinal blockade of WNT signaling pathways inhibited the production and persistence of neuropathic pain and the accompanying neurochemical alterations without affecting normal pain sensitivity and locomotor activity. WNT signaling activation stimulated production of the proinflammatory cytokines IL-18 and TNF-? and regulated the NR2B glutamate receptor and Ca2+-dependent signals through the ?-catenin pathway in the spinal cord. These findings indicate a critical mechanism underlying the pathogenesis of neuropathic pain and suggest that targeting the WNT signaling pathway may be an effective approach for treating neuropathic pain, including bone cancer pain. PMID:23585476

Zhang, Yan-Kai; Huang, Zhi-Jiang; Liu, Su; Liu, Yue-Peng; Song, Angela A.; Song, Xue-Jun

2013-01-01

446

Evolving communicative complexity: insights from rodents and beyond  

PubMed Central

Social living goes hand in hand with communication, but the details of this relationship are rarely simple. Complex communication may be described by attributes as diverse as a species' entire repertoire, signallers' individualistic signatures, or complex acoustic phenomena within single calls. Similarly, attributes of social complexity are diverse and may include group size, social role diversity, or networks of interactions and relationships. How these different attributes of social and communicative complexity co-evolve is an active question in behavioural ecology. Sciurid rodents (ground squirrels, prairie dogs and marmots) provide an excellent model system for studying these questions. Sciurid studies have found that demographic role complexity predicts alarm call repertoire size, while social group size predicts alarm call individuality. Along with other taxa, sciurids reveal an important insight: different attributes of sociality are linked to different attributes of communication. By breaking social and communicative complexity down to different attributes, focused studies can better untangle the underlying evolutionary relationships and move us closer to a comprehensive theory of how sociality and communication evolve. PMID:22641825

Pollard, Kimberly A.; Blumstein, Daniel T.

2012-01-01

447

Electrochemical Techniques for Subsecond Neurotransmitter Detection in Live Rodents  

PubMed Central

Alterations in neurotransmission have been implicated in numerous neurodegenerative and neuropsychiatric disorders, including Alzheimer disease, Parkinson disease, epilepsy, and schizophrenia. Unfortunately, few techniques support the measurement of real-time changes in neurotransmitter levels over multiple days, as is essential for ethologic and pharmacodynamic testing. Microdialysis is commonly used for these research paradigms, but its poor temporal and spatial resolution make this technique inadequate for measuring the rapid dynamics (milliseconds to seconds) of fast signaling neurotransmitters, such as glutamate and acetylcholine. Enzymatic microelectrode arrays (biosensors) coupled with electrochemical recording techniques have demonstrated fast temporal resolution (less than 1 s), excellent spatial resolution (micron-scale), low detection limits (?200 nM), and minimal damage (50 to 100 µm) to surrounding brain tissue. Here we discuss the benefits, methods, and animal welfare considerations of using platinum microelectrodes on a ceramic substrate for enzyme-based electrochemical recording techniques for real-time in vivo neurotransmitter recordings in both anesthetized and awake, freely moving rodents. PMID:25296011

Hascup, Kevin N; Hascup, Erin R

2014-01-01

448

Synthetic cathinones and their rewarding and reinforcing effects in rodents  

PubMed Central

Synthetic cathinones, colloquially referred to as “bath salts”, are derivatives of the psychoactive alkaloid cathinone found in Catha edulis (Khat). Since the mid-to-late 2000’s, these amphetamine-like psychostimulants have gained popularity amongst drug users due to their potency, low cost, ease of procurement, and constantly evolving chemical structures. Concomitant with their increased use is the emergence of a growing collection of case reports of bizarre and dangerous behaviors, toxicity to numerous organ systems, and death. However, scientific information regarding the abuse liability of these drugs has been relatively slower to materialize. Recently we have published several studies demonstrating that laboratory rodents will readily self-administer the “first generation” synthetic cathinones methylenedioxypyrovalerone (MDPV) and methylone via the intravenous route, in patterns similar to those of methamphetamine. Under progressive ratio schedules of reinforcement, the rank order of reinforcing efficacy of these compounds are MDPV ? methamphetamine > methylone. MDPV and methylone, as well as the “second generation” synthetic cathinones ?-pyrrolidinovalerophenone (?-PVP) and 4-methylethcathinone (4-MEC), also dose-dependently increase brain reward function. Collectively, these findings indicate that synthetic cathinones have a high abuse and addiction potential and underscore the need for future assessment of the extent and duration of neurotoxicity induced by these emerging drugs of abuse. PMID:25328910

Watterson, Lucas R.; Olive, M. Foster

2014-01-01

449

Heterochrony and patterns of cranial suture closure in hystricognath rodents  

PubMed Central

Sutures, joints that allow one bone to articulate with another through intervening fibrous connective tissue, serve as major sites of bone expansion during postnatal craniofacial growth in the vertebrate skull and represent an aspect of cranial ontogeny which may exhibit functional and phylogenetic correlates. Suture evolution among hystricognath rodents, an ecologically diverse group represented here by 26 species, is examined using sequence heterochrony methods, i.e. event pairing and parsimov. Although minor nuances in suture closure sequence exist between species, the overall sequence was found to be conserved both across the hystricognath group and, to an increasing degree, within selected clades. At species level, suture closure pattern exhibited a significant positive correlation with patterns previously reported for hominoids. Patterns for most clades revealed the first sutures to close are those contacting the exoccipital, interparietal, and palatine bones. Heterochronic shifts were found along 19 of 35 branches within the hystricognath phylogeny. The number of shifts per node ranged from one to seven events and, overall, involved 21 of 34 suture sites. The topology generated by parsimony analyses of the event pair matrix yielded only one grouping that was congruent with the evolutionary relationships, compiled from morphological and molecular studies, taken as framework. Sutures contacting the exoccipital displayed the highest levels of most complete closure across all species. Level of suture closure is negatively correlated with cranial length (P < 0.05). Differing life history and locomotory strategies are coupled in part with differing suture closure patterns among several species. PMID:19245501

Wilson, Laura A B; Sánchez-Villagra, Marcelo R

2009-01-01

450

Validating Excised Rodent Lungs for Functional Hyperpolarized Xenon-129 MRI  

PubMed Central

Ex vivo rodent lung models are explored for physiological measurements of respiratory function with hyperpolarized (hp) 129Xe MRI. It is shown that excised lung models allow for simplification of the technical challenges involved and provide valuable physiological insights that are not feasible using in vivo MRI protocols. A custom designed breathing apparatus enables MR images of gas distribution on increasing ventilation volumes of actively inhaled hp 129Xe. Straightforward hp 129Xe MRI protocols provide residual lung volume (RV) data and permit for spatially resolved tracking of small hp 129Xe probe volumes during the inhalation cycle. Hp 129Xe MRI of lung function in the excised organ demonstrates the persistence of post mortem airway responsiveness to intravenous methacholine challenges. The presented methodology enables physiology of lung function in health and disease without additional regulatory approval requirements and reduces the technical and logistical challenges with hp gas MRI experiments. The post mortem lung functional data can augment histological measurements and should be of interest for drug development studies. PMID:24023683

Lilburn, David M. L.; Hughes-Riley, Theodore; Six, Joseph S.; Stupic, Karl F.; Shaw, Dominick E.; Pavlovskaya, Galina E.; Meersmann, Thomas

2013-01-01

451

The effects of dietary restriction on oxidative stress in rodents  

PubMed Central

Oxidative stress is observed during aging and in numerous age-related diseases. Dietary restriction (DR) is a regimen that protects against disease and extends lifespan in multiple species. However, it is unknown how DR mediates its protective effects. One prominent and consistent effect of DR in a number of systems is the ability to reduce oxidative stress and damage. The purpose of this review is to comprehensively examine the hypothesis that dietary restriction reduces oxidative stress in rodents by decreasing reactive oxygen species (ROS) production and increasing antioxidant enzyme activity, leading to an overall reduction of oxidative damage to macromolecules. The literature reveals that the effects of DR on oxidative stress are complex and likely influenced by a variety of factors, including sex, species, tissue examined, types of ROS and antioxidant enzymes examined, and duration of DR. Here we present a comprehensive review of the existing literature on the effect of DR on mitochondrial ROS generation, antioxidant enzymes and oxidative damage. In a majority of studies, dietary restriction had little effect on mitochondrial ROS production or antioxidant activity. On the other hand, DR decreased oxidative damage in the majority of cases. Although the effects of DR on endogenous antioxidants are mixed, we find that glutathione levels are the most likely antioxidant to be increased by dietary restriction, which supports the emerging redox-stress hypothesis of aging. PMID:23743291

Walsh, Michael E.; Shi, Yun; Van Remmen, Holly

2013-01-01

452

Unstable chromosome sites and evolutionary rearrangements in akodont rodents (Cricetidae).  

PubMed

Evolutionary rearrangements producing changes in chromosome 1 of Akodon molinae were traced by comparing the G banding patterns of the karyotypes from six species of akodont rodents. It was possible to subdivide chromosome 1 of A. molinae into unstable and stable regions. Most of the spontaneous rearrangements of chromosome 1 appearing in passages 116-128 of a continuous line of A. molinae cells (AKm line) occurred in the unstable regions which comprise repetitive DNA sequences favouring the setting up of heteroduplexes leading to rearrangements. When AKm cells were irradiated with UV light it was observed that unstable regions of chromosome 1 showed higher rates of unscheduled DNA synthesis (UD) than stable areas. A differential degree of condensation making certain regions of the chromatin fibril more accessible to repair enzymes or a better target for damage, is probably the cause of the variable response to UV light, and perhaps to most clastogenic agents (including those responsible for spontaneous rearrangements). Thus, the distribution of repetitive DNA sequences, the structure of the chromatin fibril and the efficiency of the DNA repair machinery may be important factors in the origin of spontaneous chromosomal rearrangements. PMID:3525017

Bianchi, N O; Bianchi, M S

1986-01-01

453

South American mammal zoogeography: evidence from convergent evolution in desert rodents.  

PubMed Central

Current theories regarding colonization of South America by mammals are divided between those supported by fossil evidence, which suggest the original mammal fauna of the isolated continent was augmented by early immigrants (primates, caviomorph rodents, and later, procyonids) with a final large influx of northern mammals occurring with the formation of the Panama land bridge, and an opposing view which states that the purported "recent invaders" are too taxonomically and ecologically differentiated to have colonized since the land bridge arose. The second theory suggests that most extant mammals entered before the Plio-Pleistocene land connection. An analysis of degree of physiological adaptation, natural history, distribution patterns, and a multivariate assessment of convergent evolution of Monte Desert rodents indicate that South American cricetine rodents are not highly specialized for desert life. Their degree of adaptation could be accounted for, in large part, by adaptations for arid or semiarid Andean habitats. No Monte Desert rodent has developed the specialized desert traits that have evolved in most desert rodent faunas of the world, although extinct marsupials similar to living bipedal desert rodents were present in the Monte as recently as late Pliocene. Evidence suggests that Monte caviomorphs have been associated with the desert for a longer period than cricetines, and that the latter represent a fairly recent invasion of the Monte Desert. The data thus support the first hypothesis of South American mammal colonization. PMID:1057165

Mares, M A

1975-01-01

454

Indirect food web interactions mediated by predator–rodent dynamics: relative roles of lemmings and voles  

PubMed Central

Production cycles in birds are proposed as prime cases of indirect interactions in food webs. They are thought to be driven by predators switching from rodents to bird nests in the crash phase of rodent population cycles. Although rodent cycles are geographically widespread and found in different rodent taxa, bird production cycles appear to be most profound in the high Arctic where lemmings dominate. We hypothesized that this may be due to arctic lemmings inducing stronger predator responses than boreal voles. We tested this hypothesis by estimating predation rates in dummy bird nests during a rodent cycle in low-Arctic tundra. Here, the rodent community consists of a spatially variable mix of one lemming (Lemmus lemmus) and two vole species (Myodes rufocanus and Microtus oeconomus) with similar abundances. In consistence with our hypothesis, lemming peak abundances predicted well crash-phase nest predation rates, whereas the vole abundances had no predictive ability. Corvids were found to be the most important nest predators. Lemmings appear to be accessible to the whole predator community which makes them particularly powerful drivers of food web dynamics. PMID:24173526

Ims, Rolf A.; Henden, John-André; Thingnes, Anders V.; Killengreen, Siw T.

2013-01-01

455

Study of hantavirus infection in captive breed colonies of wild rodents.  

PubMed

Wild sigmondontine rodents are known to be the reservoir of several serotypes of New World hantaviruses. The mechanism of viral transmission is by aerosol inhalation of the excreta from infected rodents. Considering that the captive breed colonies of various wild mammals may present a potential risk for hantaviral transmission, we examined 85 specimens of Thrichomys spp. (Echimyidae) and 17 speciemens of Nectomys squamipes (Sigmodontinae) from our colony for the presence of hantavirus infections. Blood samples were assayed for the presence of antibodies to Andes nucleocapsid antigen using enzyme-linked immunosorbent assay (ELISA). Additionally, serum samples from workers previously exposed to wild rodents, in the laboratories where the study was conducted, were also tested by ELISA to investigate prevalence of anti-hantavirus IgG antibodies. All blood samples were negative for hantavirus antibodies. Although these results suggest that those rodent's colonies are hantavirus free, the work emphasizes the need for hantavirus serological monitoring in wild colonized rodents and secure handling potentially infected rodents as important biosafety measures. PMID:15558166

Oliveira, R C; Rozental, T; Alves-Corrêa, A A; D'Andrea, P S; Schatzmayr, H G; Cerqueira, R; Lemos, E R S

2004-10-01

456

A comparison of bats and rodents as reservoirs of zoonotic viruses: are bats special?  

PubMed Central

Bats are the natural reservoirs of a number of high-impact viral zoonoses. We present a quantitative analysis to address the hypothesis that bats are unique in their propensity to host zoonotic viruses based on a comparison with rodents, another important host order. We found that bats indeed host more zoonotic viruses per species than rodents, and we identified life-history and ecological factors that promote zoonotic viral richness. More zoonotic viruses are hosted by species whose distributions overlap with a greater number of other species in the same taxonomic order (sympatry). Specifically in bats, there was evidence for increased zoonotic viral richness in species with smaller litters (one young), greater longevity and more litters per year. Furthermore, our results point to a new hypothesis to explain in part why bats host more zoonotic viruses per species: the stronger effect of sympatry in bats and more viruses shared between bat species suggests that interspecific transmission is more prevalent among bats than among rodents. Although bats host more zoonotic viruses per species, the total number of zoonotic viruses identified in bats (61) was lower than in rodents (68), a result of there being approximately twice the number of rodent species as bat species. Therefore, rodents should still be a serious concern as reservoirs of emerging viruses. These findings shed light on disease emergence and perpetuation mechanisms and may help lead to a predictive framework for identifying future emerging infectious virus reservoirs. PMID:23378666

Luis, Angela D.; Hayman, David T. S.; O'Shea, Thomas J.; Cryan, Paul M.; Gilbert, Amy T.; Pulliam, Juliet R. C.; Mills, James N.; Timonin, Mary E.; Willis, Craig K. R.; Cunningham, Andrew A.; Fooks, Anthony R.; Rupprecht, Charles E.; Wood, James L. N.; Webb, Colleen T.

2013-01-01

457

A comparison of bats and rodents as reservoirs of zoonotic viruses: are bats special?  

USGS Publications Warehouse

Bats are the natural reservoirs of a number of high-impact viral zoonoses. We present a quantitative analysis to address the hypothesis that bats are unique in their propensity to host zoonotic viruses based on a comparison with rodents, another important host order. We found that bats indeed host more zoonotic viruses per species than rodents, and we identified life-history and ecological factors that promote zoonotic viral richness. More zoonotic viruses are hosted by species whose distributions overlap with a greater number of other species in the same taxonomic order (sympatry). Specifically in bats, there was evidence for increased zoonotic viral richness in species with smaller litters (one young), greater longevity and more litters per year. Furthermore, our results point to a new hypothesis to explain in part why bats host more zoonotic viruses per species: the stronger effect of sympatry in bats and more viruses shared between bat species suggests that interspecific transmission is more prevalent among bats than among rodents. Although bats host more zoonotic viruses per species, the total number of zoonotic viruses identified in bats (61) was lower than in rodents (68), a result of there being approximately twice the number of rodent species as bat species. Therefore, rodents should still be a serious concern as reservoirs of emerging viruses. These findings shed light on disease emergence and perpetuation mechanisms and may help lead to a predictive framework for identifying future emerging infectious virus reservoirs.

Luis, Angela D.; Hayman, David T.S.; O'Shea, Thomas J.; Cryan, Paul M.; Gilbert, Amy T.; Pulliam, Juliet R.C.; Mills, James N.; Timonin, Mary E.; Willis, Craig K.R.; Cunningham, Andrew A.; Fooks, Anthony R.; Rupprecht, Charles E.; Wood, James L.N.; Webb, Colleen T.

2013-01-01

458

Bartonella Genotypes in Fleas (Insecta: Siphonaptera) Collected from Rodents in the Negev Desert, Israel?  

PubMed Central

Fleas collected from rodents in the Negev Desert in southern Israel were molecularly screened for Bartonella species. A total of 1,148 fleas, collected from 122 rodents belonging to six species, were pooled in 245 pools based on flea species, sex, and rodent host species. Two Bartonella gene fragments, corresponding to RNA polymerase B (rpoB) and citrate synthase (gltA), were targeted, and 94 and 74 flea pools were found positive by PCR, respectively. The Bartonella 16S-23S internal transcribed spacer (ITS) region was also targeted, and 66 flea pools were found to be positive by PCR. Sixteen different Bartonella gltA genotypes were detected in 94 positive flea pools collected from 5 different rodent species, indicating that fleas collected from each rodent species can harbor several Bartonella genotypes. Based on gltA analysis, identified Bartonella genotypes were highly similar or identical to strains previously detected in rodent species from different parts of the world. A gltA fragment 100% similar to Bartonella henselae was detected in one flea pool. Another 2 flea pools contained gltA fragments that were closely related to B. henselae (98% similarity). The high sequence similarities to the zoonotic pathogen B. henselae warrant further investigation. PMID:20802081

Morick, Danny; Krasnov, Boris R.; Khokhlova, Irina S.; Shenbrot, Georgy I.; Kosoy, Michael Y.; Harrus, Shimon

2010-01-01

459

Different scaling of white matter volume, cortical connectivity, and gyrification across rodent and primate brains  

PubMed Central

Expansion of the cortical gray matter in evolution has been accompanied by an even faster expansion of the subcortical white matter volume and by folding of the gray matter surface, events traditionally considered to occur homogeneously across mammalian species. Here we investigate how white matter expansion and cortical folding scale across species of rodents and primates as the gray matter gains neurons. We find very different scaling rules of white matter expansion across the two orders, favoring volume conservation and smaller propagation times in primates. For a similar number of cortical neurons, primates have a smaller connectivity fraction and less white matter volume than rodents; moreover, as the cortex gains neurons, there is a much faster increase in white matter volume and in its ratio to gray matter volume in rodents than in primates. Order-specific scaling of the white matter can be attributed to different scaling of average fiber caliber and neuronal connectivity in rodents and primates. Finally, cortical folding increases as different functions of the number of cortical neurons in rodents and primates, scaling faster in the latter than in the former. While the neuronal rules that govern gray and white matter scaling are different across rodents and primates, we find that they can be explained by the same unifying model, with order-specific exponents. The different scaling of the white matter has implications for the scaling of propagation time and computational capacity in evolution, and calls for a reappraisal of developmental models of cortical expansion in evolution. PMID:23576961

Ventura-Antunes, Lissa; Mota, Bruno; Herculano-Houzel, Suzana

2013-01-01

460

Field efficacy of deltamethrin for rodent flea control in San Bernardino County, California, USA.  

PubMed

A study was conducted to determine the initial and residual activity of deltamethrin (0.05% dust) applied to rodent burrows (at approximately 14 g/burrow) against fleas in the Silverwood Lake area of San Bernardino County. In initial toxicity (2-d post-treatment), deltamethrin provided 97% flea control and in residual toxicity it resulted in 68% control of the rodent fleas at 15-d post-treatment. The flea fauna consisted of Oropsylla montana (89.9%) and Hoplopsylls anomalus (10.1%). All rodents captured in this study were California ground squirrels, Spermophilus beecheyi. In mark-release-recapture trials, using the microchip identification implant method at the treatment site, the recapture rate of rodents was 29% from 2- to 58-d post-treatment, declining to 21% after 98 d. In the tail-clip method at the treatment site, the recapture rate of 40% at 15-d post-treatment rose to 87% and 73% at 56- and 58-d post-treatment, respectively. At the control site, the recapture rate of 100% at 15-d post-post-treatment dropped to 20% after 98 d. In another trial at Camp Cedar Crest in the Running Springs area, deltamethrin applied to rodent burrows resulted in 70% control of fleas infesting S. beecheyi. Based on the two trials, deltamethrin showed a good initial control of rodent fleas in enzootic or epizootic plague control. PMID:15707280

Mian, Lal S; Hitchcock, James C; Madon, Minoo B; Myers, Charles M

2004-12-01