INBREEDING IN DARWIN'S MEDIUM GROUND FINCHES (GEOSPIZA FORTIS)

We studied the frequency and causes of inbreeding and its effect on reproductive success in a population of Darwin's Medium Ground Finches (Geospiza fortis) on Isla Daphne Major, Galápagos, during four breeding seasons (1981, 1983, 1984, and 1987). Pedigree analysis showed that levels of inbreeding were low but comparable with those observed in other passerine birds. For pairs with at least half of their grandparents known, approximately 20% of all pairings were between detectably related birds. The frequency of pairings between closely related birds (coefficient of kinship [φ] ≥ 0.250) among all pairs was 0.6%. We detected no effect of inbreeding on reproductive success, although sample sizes were small. The observed reproductive output of related pairs was not significantly different from the output of unrelated pairs, and there was no correlation between a pair's kinship coefficient and an estimate of the potential magnitude of inbreeding depression. Comparisons with a study of Great Tits (Parus major) by van Noordwijk and Scharloo (1981) suggest that, even if present, the fitness costs of inbreeding in this population of G. fortis would be low. Observed levels of inbreeding in each breeding episode were accurately predicted by simulations of random mating in which relatedness had no influence on pairing between individuals. This result suggests that levels of inbreeding in this population are determined more by demographic factors than by behavioral avoidance of mating with kin.     

Parentage and host preference in the common cuckoo Cuculus canorus

Microsatellite DNA markers were used to investigate parentage relationships in a population of common cuckoo Cuculus canorus . Thirty adults and 55 nestlings were genotyped at six loci from blood samples collected over a four-year period. To test whether each cuckoo female specialises in parasitising one single host species (Host Preference Hypothesis), the maternal relationships were used to record each female's host choice. The results supported the Host Preference Hypothesis since no female (N=3) was recorded to have parasitised more than one of four congeneric host species breeding in the area. In contrast, the males (N=4) did not show such specialisation since two of them sired offspring reared by different host species.     

Effect of inhA and katG on isoniazid resistance and virulence of Mycobacterium bovis

Isoniazid (INH) resistance of the Mycobacterium tuberculosis Complex (MtbC) is associated with both loss of catalase activity and mutation of the inhA gene. However, the relative contributions of these changes to resistance and to the loss of virulence for guinea-pigs is unknown. In this study, a virulent strain of Mycobacterium bovis, a member of the MtbC., was exposed to increasing concentrations of INH. Two INH-resistant strains were produced which had lost catalase activity. Strain WAg405, which had a higher resistance to INH, also had a mutation in the inhA gene. This demonstrated that loss of catalase activity and mutation of inhA had a cumulative effect on INH resistance. When a functional katG gene was integrated into the genome of WAg405 the INH resistance was greatly reduced. This indicated that most of the resistance had been caused by loss of catalase activity. While the parent INH-sensitive strain was virulent for guinea-pigs, the INH-resistant strains were significantly less virulent. Integration of a functional katG gene into the most resistant strain restored full virulence. This clearly established that katG is a virulence factor for M. bovis and that mutation of the inhA gene has no effect on virulence.     

The molecular basis of venom resistance in a rattlesnake‐squirrel predator‐prey system

Understanding how interspecific interactions mould the molecular basis of adaptations in coevolving species is a long‐sought goal of evolutionary biology. Venom in predators and venom resistance proteins in prey are coevolving molecular phenotypes, and while venoms are highly complex mixtures it is unclear if prey respond with equally complex resistance traits. Here, we use a novel molecular methodology based on protein affinity columns to capture and identify candidate blood serum resistance proteins (“venom interactive proteins” [VIPs]) in California Ground Squirrels (Otospermophilus beecheyi) that interact with venom proteins from their main predator, Northern Pacific Rattlesnakes (Crotalus o. oreganus). This assay showed that serum‐based resistance is both population‐ and species‐specific, with serum proteins from ground squirrels showing higher binding affinities for venom proteins of local snakes compared to allopatric individuals. Venom protein specificity assays identified numerous and diverse candidate prey resistance VIPs but also potential targets of venom in prey tissues. Many specific VIPs bind to multiple snake venom proteins and, conversely, single venom proteins bind multiple VIPs, demonstrating that a portion of the squirrel blood serum “resistome” involves broad‐based inhibition of nonself proteins and suggests that resistance involves a toxin scavenging mechanism. Analyses of rates of evolution of VIP protein homologues in related mammals show that most of these proteins evolve under purifying selection possibly due to molecular constraints that limit the evolutionary responses of prey to rapidly evolving snake venom proteins. Our method represents a general approach to identify specific proteins involved in co‐evolutionary interactions between species at the molecular level.     

Landscape Features Fail to Explain Spatial Genetic Structure in White-Tailed Deer Across Ohio,USA

Landscape features influence wildlife movements across spatial scales and have the potential to influence the spread of disease. Chronic wasting disease (CWD) is a fatal prion disease affecting members of the family Cervidae, particularly white-tailed deer (Odocoileus virginianus), and the first positive CWD case in a wild deer in Ohio, USA, was recorded in 2020. Landscape genetics approaches are increasingly used to better understand potential pathways for CWD spread in white-tailed deer, but little is known about genetic structure of white-tailed deer in Ohio. The objectives of our study were to evaluate spatial genetic structure in white-tailed deer across Ohio and compare the support for isolation by distance (IBD) and isolation by landscape resistance (IBR) models in explaining this structure. We collected genetic data from 619 individual deer from 24 counties across Ohio during 2007–2009. We used microsatellite genotypes from 619 individuals genotyped at 11 loci and haplotypes from a 547-base pair fragment of the mitochondrial DNA control region. We used spatial and non-spatial genetic clustering tests to evaluate genetic structure in both types of genetic data and empirically optimized landscape resistance surfaces to compare IBD and IBR using microsatellite data. Non-spatial genetic clustering tests failed to detect spatial genetic structure, whereas spatial genetic clustering tests indicated subtle spatial genetic structure. The IBD model consistently outperformed IBR models that included land cover, traffic volume, and streams. Our results indicated widespread genetic connectivity of white-tailed deer across Ohio and negligible effects of landscape features. These patterns likely reflect some combination of minimal resistive effects of landscape features on white-tail deer movement in Ohio and the effects of regional recolonization or translocation. We encourage continued CWD surveillance in Ohio, particularly in the proximity of confirmed cases. © 2021 The Wildlife Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.     

Eph receptors and their ligands: Promising molecular biomarkers and therapeutic targets in prostate cancer

Although at present, there is a high incidence of prostate cancer, particularly in the Western world, mortality from this disease is declining and occurs primarily only from clinically significant late stage tumors with a poor prognosis. A major current focus of this field is the identification of new biomarkers which can detect earlier, and more effectively, clinically significant tumors from those deemed “low risk”, as well as predict the prognostic course of a particular cancer. This strategy can in turn offer novel avenues for targeted therapies. The large family of Receptor Tyrosine Kinases, the Ephs, and their binding partners, the ephrins, has been implicated in many cancers of epithelial origin through stimulation of oncogenic transformation, tumor angiogenesis, and promotion of increased cell survival, invasion and migration. They also show promise as both biomarkers of diagnostic and prognostic value and as targeted therapies in cancer. This review will briefly discuss the complex roles and biological mechanisms of action of these receptors and ligands and, with regard to prostate cancer, highlight their potential as biomarkers for both diagnosis and prognosis, their application as imaging agents, and current approaches to assessing them as therapeutic targets. This review demonstrates the need for future studies into those particular family members that will prove helpful in understanding the biology and potential as targets for treatment of prostate cancer.     

Perinatal physiology in cloned and normal calves: hematologic and biochemical profiles

Although a majority of clones are born normal and apparently healthy, mortality rates of nearly 30% are described in many reports. Such losses are a major limitation of cloning technology and represent substantial economic investment as well as justifiable animal health and welfare concerns. Prospective, controlled studies are needed to understand fully the causes of neonatal mortality in clones and to develop preventive and therapeutic strategies to minimize losses. We report here the findings of studies on the hematologic and biochemical profiles of cloned and control calves in the immediate 48-h postpartum period. Cloned calves were similar to control calves for a majority of parameters studied including blood gases, concentrations of plasma proteins, minerals and electrolytes, and white blood cell, neutrophil, lymphocyte, and platelet counts. The most notable differences between clones and controls in this study were reduced red- and white-blood cell counts in clones at birth and 1 h of age. As a group, plasma electrolyte concentrations were more variable in clones, and the variability tended to be shifted either higher (sodium, chloride) or lower (potassium, bicarbonate) than in controls. Previously, we noted differences in carbohydrate parameters, the length of time required for clones to make the neonatal adaptation to life ex utero, and morphology of the cloned placenta. Taken together, our findings suggest that cloned calves experience greater difficulty adjusting to life ex utero and that further research is warranted to determine the nature of the relationship between the physiological differences noted here in clones at birth and concomitant abnormal placental morphology.     

Manipulation of immune responses to Mycobacterium bovis by vaccination with IL-2- and IL-18-secreting recombinant bacillus Calmette Guerin

Bacillus Calmette Guerin (BCG) has been reported to show variable efficacy as a vaccine against tuberculosis. We demonstrated that the secretion of biologically active IL-2 (rBCG/IL-2),but not IL-18 (rBCG/IL-18), by BCG improves its ability to induce and maintain a strong type 1 immune response in BALB/c mice. rBCG/IL-2 induced significantly higher Ag-specific proliferative responses, high IFN-gamma production and serum titres of IgG2a 16 weeks after vaccination. This immune profile was correlated to an increased rate of clearance of non-pathogenic mycobacteria (live BCG delivered intranasally). Surprisingly, however,this strong type 1 immune profile induced no greater protective immunity against aerosol challenge with virulent Mycobacterium bovis than that induced by normal BCG (nBCG). By comparison,vaccination with rBCG/IL-18 was found to induce significantly less IFN-gamma production in splenic lymphocytes than nBCG.This impaired induction of IFN-gamma was correlated to a significantly lower protective efficacy against M. bovis challenge, as compared to nBCG. The data suggest that manipulation of the immune response to tuberculosis and tuberculosis vaccines will require a more complete understanding of the factors that are important in generating a protective immune response.     

Effects of Starvation on Physiological Activity and Chlorine Disinfection Resistance in Escherichia coli O157:H7

Escherichia coli O157:H7 can persist for days to weeks in microcosms simulating natural conditions. In this study, we used a suite of fluorescent, in situ stains and probes to assess the influence of starvation on physiological activity based on membrane potential (rhodamine 123 assay), membrane integrity (LIVE/DEAD BacLight kit), respiratory activity (5-cyano-2,3-di-4-tolyl-tetrazolium chloride assay), intracellular esterase activity (ScanRDI assay), and 16S rRNA content. Growth-dependent assays were also used to assess substrate responsiveness (direct viable count [DVC] assay), ATP activity (MicroStar assay), and culturability (R2A agar assay). In addition, resistance to chlorine disinfection was assessed. After 14 days of starvation, the DVC values decreased, while the values in all other assays remained relatively constant and equivalent to each other. Chlorine resistance progressively increased through the starvation period. After 29 days of starvation, there was no significant difference in chlorine resistance between control cultures that had not been exposed to the disinfectant and cultures that had been exposed. This study demonstrates that E. coli O157:H7 adapts to starvation conditions by developing a chlorine resistance phenotype.     

Genetic structure in a tropical lek-breeding bird, the blue manakin (Chiroxiphia caudata) in the Brazilian Atlantic Forest

Determining the genetic structure of tropical bird populations is important for assessing potential genetic effects of future habitat fragmentation and for testing hypotheses about evolutionary mechanisms promoting diversification. Here we used 10 microsatellite DNA loci to describe levels of genetic differentiation for five populations of the lek-mating blue manakin (Chiroxiphia caudata), sampled along a 414-km transect within the largest remaining continuous tract of the highly endangered Atlantic Forest habitat in southeast Brazil. We found small but significant levels of differentiation between most populations. F(ST) values varied from 0.0 to 0.023 (overall F(ST)=0.012) that conformed to a strong isolation by distance relationship, suggesting that observed levels of differentiation are a result of migration-drift equilibrium. N(e)m values estimated using a coalescent-based method were small (相似文献