Ecological and Conservation Significance of Herpesvirus Infection in Neotropical Bats

EcoHealth - Bats are the second most diverse order of mammals and key species for ecosystem functioning, providing a wide range of ecosystem services, from pest control to seed dispersal....     

Use of Vocal Signatures for the Inventory of Free-flying Neotropical Bats1

An ongoing study is being conducted to test the efficacy of the Anabat II detector and analysis system in obtaining reliable vocal signatures for the identification of non–phyllostomid species of bats. We sampled a wide range of elevations and associated habitat types throughout Belize. Anabat provides an instantaneous output of echolocation call structure with a laptop computer. Select sequences can be saved directly to the hard drive, avoiding extraneous noise and sound distortion commonly associated with tape recorders. To date, 18 of the 37 species known or expected to occur in the study region were identified by recognizable differences in the time–frequency characteristics of echolocation calls. In general, each family is recognizable by call structure patterns and species readily separated by frequency range parameters. Species that commute or forage at high altitudes are not susceptible to capture but are conspicuous by acoustic sampling. Further work is needed to determine limitations of the equipment, establish better sampling procedures, and develop a comprehensive library of vocal signatures incorporating the range of variation inherent in each species. As this work progresses, we predict the addition of hitherto unknown species occurring within the study region.     

乌鸫繁殖习性及食性的初步研究

乌鸫的食性较杂,以昆虫为主要食物。这些昆虫是农林业的重要害虫,在抑制农林虫害的发生,维持自然生态平衡方面有较重要的作用。它的幼鸟主要以蚯蚓为食。2007年3—5月对江口中学校园的两巢乌鸫的繁殖生态行为和食性进行了初步观察。只有雌乌鸫孵化,育雏前期雌乌喂雏的次数较多,在后期雄鸟喂食的次数较多。     

Roosting behavior of a Neotropical migrant songbird, the northern waterthrush Seiurus noveboracensis, during the non-breeding season

Several species of Nearctic-Neotropical migratory songbirds appear to form roosting aggregations while on their wintering grounds but little is understood about the ecology of this behavior. We studied roosting behavior and patterns of roost habitat selection in the northern waterthrush Seiurus noveboracensis , during three winter years (2002–2004) in Puerto Rico using radio telemetry. Overall, red mangrove was selected for roosting disproportionately to its availability. Regardless of diurnal habitat used, 87% (n=86) of northern waterthrush selected dense stands of coastal red mangrove for roost sites. Individuals traveled up to 2 km to access roost sites in this habitat on a daily basis. The majority (8 of 14) of individuals roosted alone, while others roosted in loose aggregations near communal roosts of gray kingbirds Tyrannus dominicensis . Patterns of roost site selection did not vary by sex. Individuals showing aggressive response to playback during the day, however, selected roost sites significantly closer to the coast. Several additional migratory and resident bird species also used red mangrove for night-time roosting habitat. Red mangrove may be a critical nocturnal roosting habitat for bird populations that live in proximity to coastal areas in the Neotropics. The benefits of nocturnal roosting behavior as well as why individuals appear to select red mangrove remain poorly understood.     

Disparate Metabolic Responses in Mice Fed a High-Fat Diet Supplemented with Maize-Derived Non-Digestible Feruloylated Oligo- and Polysaccharides Are Linked to Changes in the Gut Microbiota

Studies have suggested links between colonic fermentation of dietary fibers and improved metabolic health. The objectives of this study were to determine if non-digestible feruloylated oligo- and polysaccharides (FOPS), a maize-derived dietary fiber, could counteract the deleterious effects of high-fat (HF) feeding in mice and explore if metabolic benefits were linked to the gut microbiota. C57BL/6J mice (n = 8/group) were fed a low-fat (LF; 10 kcal% fat), HF (62 kcal% fat), or HF diet supplemented with FOPS (5%, w/w). Pronounced differences in FOPS responsiveness were observed: four mice experienced cecal enlargement and enhanced short chain fatty acid production, indicating increased cecal fermentation (F-FOPS). Only these mice displayed improvements in glucose metabolism compared with HF-fed mice. Blooms in the gut microbial genera Blautia and Akkermansia were observed in three of the F-FOPS mice; these shifts were associated with reductions in body and adipose tissue weights compared with the HF-fed control mice. No improvements in metabolic markers or weights were detected in the four mice whose gut microbiota did not respond to FOPS. These findings demonstrate that FOPS-induced improvements in weight gain and metabolic health in mice depended on the ability of an individual’s microbiota to ferment FOPS.     

Timing of Immune Escape Linked to Success or Failure of Vaccination

Successful vaccination against HIV should limit viral replication sufficiently to prevent the emergence of viral immune escape mutations. Broadly directed immunity is likely to be required to limit opportunities for immune escape variants to flourish. We studied the emergence of an SIV Gag cytotoxic T cell immune escape variant in pigtail macaques expressing the Mane-A*10 MHC I allele using a quantitative RT-PCR to measure viral loads of escape and wild type variants. Animals receiving whole Gag expressing vaccines completely controlled an SIV_mac251 challenge, had broader CTL responses and exhibited minimal CTL escape. In contrast, animals vaccinated with only a single CTL epitope and challenged with the same SIV_mac251 stock had high levels of viral replication and rapid CTL escape. Unvaccinated naïve animals exhibited a slower emergence of immune escape variants. Thus narrowly directed vaccination against a single epitope resulted in rapid immune escape and viral levels equivalent to that of naïve unvaccinated animals. These results emphasize the importance of inducing broadly directed HIV-specific immunity that effectively quashes early viral replication and limits the generation of immune escape variants. This has important implications for the selection of HIV vaccines for expanded human trials.     

Ecosystem Functions across Trophic Levels Are Linked to Functional and Phylogenetic Diversity

In experimental systems, it has been shown that biodiversity indices based on traits or phylogeny can outperform species richness as predictors of plant ecosystem function. However, it is unclear whether this pattern extends to the function of food webs in natural ecosystems. Here we tested whether zooplankton functional and phylogenetic diversity explains the functioning of 23 natural pond communities. We used two measures of ecosystem function: (1) zooplankton community biomass and (2) phytoplankton abundance (Chl a). We tested for diversity-ecosystem function relationships within and across trophic levels. We found a strong correlation between zooplankton diversity and ecosystem function, whereas local environmental conditions were less important. Further, the positive diversity-ecosystem function relationships were more pronounced for measures of functional and phylogenetic diversity than for species richness. Zooplankton and phytoplankton biomass were best predicted by different indices, suggesting that the two functions are dependent upon different aspects of diversity. Zooplankton community biomass was best predicted by zooplankton trait-based functional richness, while phytoplankton abundance was best predicted by zooplankton phylogenetic diversity. Our results suggest that the positive relationship between diversity and ecosystem function can extend across trophic levels in natural environments, and that greater insight into variation in ecosystem function can be gained by combining functional and phylogenetic diversity measures.     

Rates of Viral Evolution Are Linked to Host Geography in Bat Rabies

Rates of evolution span orders of magnitude among RNA viruses with important implications for viral transmission and emergence. Although the tempo of viral evolution is often ascribed to viral features such as mutation rates and transmission mode, these factors alone cannot explain variation among closely related viruses, where host biology might operate more strongly on viral evolution. Here, we analyzed sequence data from hundreds of rabies viruses collected from bats throughout the Americas to describe dramatic variation in the speed of rabies virus evolution when circulating in ecologically distinct reservoir species. Integration of ecological and genetic data through a comparative Bayesian analysis revealed that viral evolutionary rates were labile following historical jumps between bat species and nearly four times faster in tropical and subtropical bats compared to temperate species. The association between geography and viral evolution could not be explained by host metabolism, phylogeny or variable selection pressures, and instead appeared to be a consequence of reduced seasonality in bat activity and virus transmission associated with climate. Our results demonstrate a key role for host ecology in shaping the tempo of evolution in multi-host viruses and highlight the power of comparative phylogenetic methods to identify the host and environmental features that influence transmission dynamics.     

Genetic Variants of Angiotensin-Converting Enzyme Are Linked to Autism: A Case-Control Study

BackgroundAutism is a disease of complex nature with a significant genetic component. The importance of renin-angiotensin system (RAS) elements in cognition and behavior besides the interaction of angiotensin II (Ang II), the main product of angiotensin-converting enzyme (ACE), with neurotransmitters in CNS, especially dopamine, proposes the involvement of RAS in autism. Since the genetic architecture of autism has remained elusive, here we postulated that genetic variations in RAS are associated with autism.MethodsConsidering the relation between the three polymorphisms of ACE (I/D, rs4343 and rs4291) with the level of ACE activity, we have investigated this association with autism, in a case-control study. Genotype and allele frequencies of polymorphisms were determined in DNAs extracted from venous blood of 120 autistic patients and their age and sex-matched healthy controls, using polymerase chain reaction (PCR) and PCR–restriction fragment length polymorphism (PCR–RFLP) methods.ResultsThere were strong associations between both DD genotype of ACE I/D and the D allele, with autism (P = 0.006, OR = 2.9, 95% CI = 1.64–5.13 and P = 0.006, OR = 2.18, 95% CI = 1.37–3.48 respectively). Furthermore, a significant association between the G allele of rs4343 and autism was observed (P = 0.006, OR = 1.84, 95%CI = 1.26–2.67). Moreover, haplotype analysis revealed an association between DTG haplotype and autism (P = 0.008).ConclusionOur data suggests the involvement of RAS genetic diversity in increasing the risk of autism.     

OM Mutations in DROSOPHILA ANANASSAE Are Linked to Insertions of a Transposable Element

It has been hypothesized that Om mutability in Drosophila ananassae (involving spontaneous mutation at 20 loci, resulting in semidominant, nonpleiotropic eye morphology defects) was due to insertion of a transposable element, tom. One particularly unstable X-linked Om allele produced several derivatives, one of which has a more extreme Om phenotype and was accompanied by a singed bristle mutant, sn ^9g. DNA probes from the sn locus of D. melanogaster were used to clone the homologous region of D. ananassae. Analysis of sn^9g DNA detected a 6.5-kb insert. Genomic Southern blotting and in situ hybridization techniques showed that this insert is repetitive and dispersed. The existence of the tom element is supported by genetic mapping that established homology between the 6.5-kb sn^9g insert and Om mutants at the four X-linked loci tested.     

Dual RNA-Seq of Human Leprosy Lesions Identifies Bacterial Determinants Linked to Host Immune Response

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The Dithiol Glutaredoxins of African Trypanosomes Have Distinct Roles and Are Closely Linked to the Unique Trypanothione Metabolism

Trypanosoma brucei, the causative agent of African sleeping sickness, possesses two dithiol glutaredoxins (Grx1 and Grx2). Grx1 occurs in the cytosol and catalyzes protein deglutathionylations with k_cat/K_m-values of up to 2 × 10⁵ m⁻¹ s⁻¹. It accelerates the reduction of ribonucleotide reductase by trypanothione although less efficiently than the parasite tryparedoxin and has low insulin disulfide reductase activity. Despite its classical CPYC active site, Grx1 forms dimeric iron-sulfur complexes with GSH, glutathionylspermidine, or trypanothione as non-protein ligands. Thus, contrary to the generally accepted assumption, replacement of the Pro is not a prerequisite for cluster formation. T. brucei Grx2 shows an unusual CQFC active site, and orthologues occur exclusively in trypanosomatids. Grx2 is enriched in mitoplasts, and fractionated digitonin lysis resulted in a co-elution with cytochrome c, suggesting localization in the mitochondrial intermembrane space. Grx2 catalyzes the reduction of insulin disulfide but not of ribonucleotide reductase and exerts deglutathionylation activity 10-fold lower than that of Grx1. RNA interference against Grx2 caused a growth retardation of procyclic cells consistent with an essential role. Grx1 and Grx2 are constitutively expressed with cellular concentrations of about 2 μm and 200 nm, respectively, in both the mammalian bloodstream and insect procyclic forms. Trypanothione reduces the disulfide form of both proteins with apparent rate constants that are 3 orders of magnitude higher than those with glutathione. Grx1 and, less efficiently, also Grx2 catalyze the reduction of GSSG by trypanothione. Thus, the Grxs play exclusive roles in the trypanothione-based thiol redox metabolism of African trypanosomes.     

Leadership and Path Characteristics during Walks Are Linked to Dominance Order and Individual Traits in Dogs

Movement interactions and the underlying social structure in groups have relevance across many social-living species. Collective motion of groups could be based on an “egalitarian” decision system, but in practice it is often influenced by underlying social network structures and by individual characteristics. We investigated whether dominance rank and personality traits are linked to leader and follower roles during joint motion of family dogs. We obtained high-resolution spatio-temporal GPS trajectory data (823,148 data points) from six dogs belonging to the same household and their owner during 14 30–40 min unleashed walks. We identified several features of the dogs'' paths (e.g., running speed or distance from the owner) which are characteristic of a given dog. A directional correlation analysis quantifies interactions between pairs of dogs that run loops jointly. We found that dogs play the role of the leader about 50–85% of the time, i.e. the leader and follower roles in a given pair are dynamically interchangable. However, on a longer timescale tendencies to lead differ consistently. The network constructed from these loose leader–follower relations is hierarchical, and the dogs'' positions in the network correlates with the age, dominance rank, trainability, controllability, and aggression measures derived from personality questionnaires. We demonstrated the possibility of determining dominance rank and personality traits of an individual based only on its logged movement data. The collective motion of dogs is influenced by underlying social network structures and by characteristics such as personality differences. Our findings could pave the way for automated animal personality and human social interaction measurements.     

Perception of Odors Linked to Precise Timing in the Olfactory System

While the timing of neuronal activity in the olfactory bulb (OB) relative to sniffing has been the object of many studies, the behavioral relevance of timing information generated by patterned activation within the bulbar response has not been explored. Here we show, using sniff-triggered, dynamic, 2-D, optogenetic stimulation of mitral/tufted cells, that virtual odors that differ by as little as 13 ms are distinguishable by mice. Further, mice are capable of discriminating a virtual odor movie based on an optically imaged OB odor response versus the same virtual odor devoid of temporal dynamics—independently of the sniff-phase. Together with studies showing the behavioral relevance of graded glomerular responses and the response timing relative to odor sampling, these results imply that the mammalian olfactory system is capable of very high transient information transmission rates.     

Mitotic Slippage and Expression of Survivin Are Linked to Differential Sensitivity of Human Cancer Cell-Lines to the Kinesin-5 Inhibitor Monastrol

The mitotic Kinesin-5 motor proteins crosslink and slide apart antiparallel spindle microtubules, thus performing essential functions in mitotic spindle dynamics. Specific inhibition of their function by monastrol-like small molecules has been examined in clinical trials as anticancer treatment, with only partial success. Thus, strategies that improve the efficiency of monastrol-like anticancer drugs are required. In the current study, we examined the link between sensitivity to monastrol and occurrence of mitotic slippage in several human cell-lines. We found that the rank of sensitivity to monastrol, from most sensitive to least sensitive, is: AGS>HepG2>Lovo>Du145≥HT29. We show correlation between the sensitivity of a particular cell-line to monastrol and the tendency of the same cell-line to undergo mitotic slippage. We also found that in the monastrol resistant HT29 cells, prolonged monastrol treatments increase mRNA and protein levels of the chromosomal passenger protein survivin. In contrast, survivin levels are not increased by this treatment in the monastrol-sensitive AGS cells. We further show that over-expression of survivin in the monastrol-sensitive AGS cells reduces mitotic slippage and increases resistance to monastrol. Finally, we show that during short exposure to monastrol, Si RNA silencing of survivin expression reduces cell viability in both AGS and HT29 cells. Our data suggest that the efficiency of anti-cancer treatment with specific kinesin-5 inhibitors may be improved by modulation of expression levels of survivin.     

Abnormal Sperm Parameters in Humans Are Indicative of an Abortive Apoptotic Mechanism Linked to the Fas-Mediated Pathway

The life cycle of many cell types can hinge on the presence of death factors that can control programmed cell death. The Fas-mediated apoptotic pathway has been implicated in controlling apoptosis during spermatogenesis in a number of mammalian species. In the human, the presence of nuclear DNA damage in ejaculated spermatozoa has pointed to a possible role for apoptosis during spermatogenesis. The presence of other molecular markers of apoptosis has, however, not been shown. More importantly, differences in these markers have not been investigated in men with normal and abnormal sperm parameters. In this study we examine for the presence of the cell surface protein Fas in ejaculated human spermatozoa. Ejaculated spermatozoa (55 samples) were labeled with anti-human Fas antibody and the number of spermatozoa displaying Fas were counted using a fluorescence-activated cell sorter (FACS). In 30/31 (96.8%) normal males (>20 million sperm per milliliter), less than 10% of the spermatozoa were Fas positive. In contrast, 14/24 (58.3%) oligozoospermic samples (<20 million sperm per milliliter) contained more than 10% Fas-positive spermatozoa. Similar differences were observed in men whose spermatozoa had poor motility and morphology. These results indicate that apoptosis is a major mechanism in regulating spermatogenesis in the human and that there are clear differences in molecular markers of apoptosis between males with normal and abnormal sperm parameters. We propose that the presence of Fas-labeled spermatozoa in the ejaculate of these men is indicative of an "abortive apoptosis" having taken place, whereby the normal apoptotic mechanisms have misfunctioned, have been overridden, or have not been completed.