Binding of [-14C]aflatoxin B1 to cellular macromolecules in the rat and hamster.

The uptake and binding of ring-labelled [-14C]aflatoxin B1 (AFB1) by rat and hamster liver and kidney has been studied, the former species being extremely sensitive to the carcinogenic action of AFB, whereas the latter is resistant. In contrast to an earlier report (Lijinsky et al, Cancer Res., 30 (1970) 2280-2283, binding of the carcinogen to nucleic acids was far greater than that to protein. Rat liver DNA bound ten times and rRNA twenty times more carcinogen than protein. There were also differences in the amount of carcinogen bound to rat liver nucleic acids compared to those of the hamster, the latter species binding lower amounts of the carcinogen. Rat liver DNA bound four times and rRNA ten times as much AFB1 6 h after carcinogen administration whereas liver protein bound AFB1 was similar for the two species. Not only was there a difference in the amount of AFB1 bound but whereas in the rat, liver nucleic acid bound carcinogen decayed with time, no such fall was seen in the hamster, this remaining at a low level throughout the 48-h time period studied. In contrast, reaction of the carcinogen with kidney macromolecules was similar for the two species. The much higher binding of AFB1 to nucleic acids than to protein might account for the potent carcinogenicity of this compound in the rat, particularly since liver protein binding does not differ between a susceptible and a resistant species. A further important factor in determining carcinogenic sensitivity may be the removal of nucleic acid bound radioactivity with time, a possible repair process.     

Assortative mating but no evidence of genetic divergence in a species characterized by a trophic polymorphism

Disruptive selection is a process that can result in multiple subgroups within a population, which is referred to as diversification. Foraging‐related diversification has been described in many taxa, but many questions remain about the contribution of such diversification to reproductive isolation and potentially sympatric speciation. Here, we use stable isotope analysis of diet and morphological analysis of body shape to examine phenotypic divergence between littoral and pelagic foraging ecomorphs in a population of pumpkinseed sunfish (Lepomis gibbosus). We then examine reproductive isolation between ecomorphs by comparing the isotopic compositions of nesting males to eggs from their nests (a proxy for maternal diet) and use nine microsatellite loci to examine genetic divergence between ecomorphs. Our data support the presence of distinct foraging ecomorphs in this population and indicate that there is significant positive assortative mating based on diet. We did not find evidence of genetic divergence between ecomorphs, however, indicating that isolation is either relatively recent or is not strong enough to result in genetic divergence at the microsatellite loci. Based on our findings, pumpkinseed sunfish represent a system in which to further explore the mechanisms by which natural and sexual selection contribute to diversification, prior to the occurrence of sympatric speciation.     

A framework for inference about carnivore density from unstructured spatial sampling of scat using detector dogs

Wildlife management often hinges upon an accurate assessment of population density. Although undeniably useful, many of the traditional approaches to density estimation such as visual counts, livetrapping, or mark–recapture suffer from a suite of methodological and analytical weaknesses. Rare, secretive, or highly mobile species exacerbate these problems through the reality of small sample sizes and movement on and off study sites. In response to these difficulties, there is growing interest in the use of non-invasive survey techniques, which provide the opportunity to collect larger samples with minimal increases in effort, as well as the application of analytical frameworks that are not reliant on large sample size arguments. One promising survey technique, the use of scat detecting dogs, offers a greatly enhanced probability of detection while at the same time generating new difficulties with respect to non-standard survey routes, variable search intensity, and the lack of a fixed survey point for characterizing non-detection. In order to account for these issues, we modified an existing spatially explicit, capture–recapture model for camera trap data to account for variable search intensity and the lack of fixed, georeferenced trap locations. We applied this modified model to a fisher (Martes pennanti) dataset from the Sierra National Forest, California, and compared the results (12.3 fishers/100 km²) to more traditional density estimates. We then evaluated model performance using simulations at 3 levels of population density. Simulation results indicated that estimates based on the posterior mode were relatively unbiased. We believe that this approach provides a flexible analytical framework for reconciling the inconsistencies between detector dog survey data and density estimation procedures. © 2011 The Wildlife Society.     

Hypoderma actaeon: an emerging myiasis in roe deer (Capreolus capreolus)

Subcutaneous larvae of Hypoderma spp. (Diptera: Oestridae) were detected in the dorsal region in 10 roe deer, Capreolus capreolus (Artiodactyla: Cervidae), hunted in central Spain between January and March 2016. All larvae were found in the inner side of the hide during the skinning of the animals. The study of the morphological features of eight larvae of different stages collected from two animals allowed the identification of Hypoderma actaeon Brauer. The small size (4–5 mm) of some of the first instars suggests that the internal lifecycle of H. actaeon may be exclusively subcutaneous. This is the first confirmation of H. actaeon in roe deer; however, further studies to assess the spread of the parasite and to follow the evolution of this myiasis in roe deer are needed.