Heritability of anti‐predatory traits: vigilance and locomotor performance in marmots

Animals must allocate some proportion of their time to detecting predators. In birds and mammals, such anti‐predator vigilance has been well studied, and we know that it may be influenced by a variety of intrinsic and extrinsic factors. Despite hundreds of studies focusing on vigilance and suggestions that there are individual differences in vigilance, there have been no prior studies examining its heritability in the field. Here, we present one of the first reports of (additive) genetic variation in vigilance. Using a restricted maximum likelihood procedure, we found that, in yellow‐bellied marmots (Marmota flaviventris), the heritability of locomotor ability (h² = 0.21), and especially vigilance (h² = 0.08), is low. These modest heritability estimates suggest great environmental variation or a history of directional selection eliminating genetic variation in these traits. We also found a significant phenotypic (r_P = ?0.09 ± 0.04, P = 0.024) and a substantial, but not significant, genetic correlation (r_A = ?0.57 ± 0.28, P = 0.082) between the two traits (slower animals are less vigilant while foraging). We found no evidence of differential survival or longevity associated with particular phenotypes of either trait. The genetic correlation may persist because of environmental heterogeneity and genotype‐by‐environment interactions maintaining the correlation, or because there are two ways to solve the problem of foraging in exposed areas: be very vigilant and rely on early detection coupled with speed to escape, or reduce vigilance to minimize time spent in an exposed location. Both strategies seem to be equally successful, and this ‘locomotor ability‐wariness’ syndrome may therefore allow slow animals to compensate behaviourally for their impaired locomotor ability.     

Tissue and Cellular Expression Patterns of Porcine CFTR: Similarities to and Differences From Human CFTR

Emerging porcine models of cystic fibrosis (CF) are expected to mimic the human disease more closely than current mouse models do. However, little is known of the tissue and cellular expression patterns of the porcine CF transmembrane conductance regulator (pCFTR) and possible differences from human CFTR (hCFTR). Here, the expression pattern of pCFTR was systematically established on the mRNA and protein levels. Using specific anti-pCFTR antibodies, the majority of the protein was immunohistochemically detected on paraffin-embedded sections and on cryostate sections in the apical cytosol of intestinal crypt epithelial cells, nasal, tracheal, and bronchial epithelial cells, and other select, mostly glandular epithelial cells. Confocal laser scanning microscopy with co-localization of the Golgi marker 58K localized the protein in the cytosol between the Golgi apparatus and the apical cell membrane with occasional punctate or diffuse staining of the apical membrane. The tissue and cellular distribution patterns were confirmed by RT-PCR from whole tissue lysates or select cells after laser capture microdissection. Thus, expression of pCFTR was found to largely resemble that of hCFTR except for the kidney, brain, and cutaneous glands, which lack expression in pigs. Species-specific differences between pCFTR and hCFTR may become relevant for future interpretations of the CF phenotype in pig models. (J Histochem Cytochem 58:785–797, 2010)     

The HDL hypothesis: does high-density lipoprotein protect from atherosclerosis?

There is unequivocal evidence of an inverse association between plasma high-density lipoprotein (HDL) cholesterol concentrations and the risk of cardiovascular disease, a finding that has led to the hypothesis that HDL protects from atherosclerosis. This review details the experimental evidence for this “HDL hypothesis”. In vitro studies suggest that HDL has a wide range of anti-atherogenic properties but validation of these functions in humans is absent to date. A significant number of animal studies and clinical trials support an atheroprotective role for HDL; however, most of these findings were obtained in the context of marked changes in other plasma lipids. Finally, genetic studies in humans have not provided convincing evidence that HDL genes modulate cardiovascular risk. Thus, despite a wealth of information on this intriguing lipoprotein, future research remains essential to prove the HDL hypothesis correct.     

Atheroma development in apolipoprotein E-null mice is not regulated by phosphorylation of p27(Kip1) on threonine 187

Excessive cellular proliferation is thought to contribute to neointimal lesion development during atherosclerosis and restenosis after angioplasty. Inhibition of cyclin-dependent kinase (CDK) activity by p27 inhibits mammalian cell growth. Mounting evidence indicates that p27 negatively regulates neointimal thickening in animal models of restenosis and atherosclerosis, and its expression in human neointimal lesions is consistent with such a protective role. Cell cycle progression is facilitated by cyclinE/CDK2-dependent phosphorylation of p27 on threonine 187 (T187) during late G1. The purpose of this study was to assess whether this phosphorylation event plays a role during atherosclerosis. To this end, we generated apolipoprotein E-null mice with both p27 alleles replaced by a mutated form non-phosphorylatable at T187 (apoE-/-p27T187A mice) and investigated the kinetics of atheroma development in these animals compared to apoE-/- controls with an intact p27 gene. Fat feeding resulted in comparable level of hypercholesterolemia in both groups of mice. Surprisingly, aortic p27 expression was not increased in fat-fed apoE-/-p27T187A mice compared with apoE-/- controls. Moreover, atheroma size, lesion cellularity, proliferation, and apoptotic rates were undistinguishable in both groups of fat-fed mice. Thus, in contrast to previous studies that highlight the importance of p27 phosphorylation at T187 on the control of p27 expression and function in different tissues and pathophysiological scenarios, our findings demonstrate that this phosphorylation event is not implicated in the control of aortic p27 expression and atheroma progression in hypercholesterolemic mice.     

Rapid transient absorption and biliary secretion of enantiomeric cholesterol in hamsters

To probe the pathway and specificity of cholesterol absorption, the synthetic enantiomer of cholesterol (ent-cholesterol) and cholesterol were labeled with deuterium, gavaged into hamsters, and measured by negative ion mass spectrometry. Initial uptake of both tracers into the intestinal mucosa at 30 min was similar but cholesterol was temporarily retained there, whereas mucosal ent-cholesterol declined rapidly with concomitantly increased enrichment in both the systemic circulation and the gut lumen. In a 3 day fecal recovery study, ent-cholesterol was quantitatively recovered in the stool, whereas cholesterol absorption was 53.2%. ent-Cholesterol given by intracardiac injection was selectively secreted into bile, and the ratio of ent-cholesterol to cholesterol tracers in the gut lumen increased down the length of the small bowel, with the largest value being found in stool. ent-Cholesterol is efficiently taken up by the intestinal mucosa and undergoes transient enterohepatic recirculation, but it is quantitatively eliminated over 3 days as a result of selective secretion into bile and selective enrichment within the lumen of the intestine. These findings suggest that cholesterol absorption is structurally specific and likely to be mediated by enantiospecific cellular proteins.     

Exclusive frugivory and seed dispersal of Rhamnus alaternus in the bird breeding season

We studied avian frugivory and seed dispersal in a dioecious shrub, Rhamnus alaternus, focusing on the quantitative and qualitative components of effectiveness. The study took place at three locations in the northeast of the Iberian Peninsula, and examined bird behaviour, intensity of feeding, and the consequences for seedling emergence. The coincidence between the bird breeding season and fruit ripening of R. alaternus in the absence of other ripe fruit, generates a monospecific interaction. The extant frugivorous species were mainly legitimate seed dispersers and their abundance was low. Sylvia melanocephala and S. undata were the most important at one site whereas S. atricapilla, Erithacus rubecula and Turdus merula predominated at the other two sites. Fruit handling took place directly on the branches. Bird species used microhabitats differently as first post-feeding perch, which usually was a short distance away. The low density of frugivorous birds in all localities, among others factors, resulted in satiation of the disperser community and many mature fruits unconsumed. Both adults and juveniles feed upon the plants and their foraging patterns are similar. Adults of S. melanocephala were observed to feed fruit to nestlings and consequently a second phase of dispersal potentially arises from the transport of fecal sacs. Pulp removal and passage through the digestive tract increased the probability of seedling emergence. This plant-dispersal interaction has important consequences, both positive and negative for the plant. Positively, the fruiting of R. alaternus at a time when other ripe fruits are not available avoids interspecific competition for seed dispersers. In addition, a low density of seed rain may reduce intraspecific competition. Negatively, the low density and small size of the breeding frugivorous bird community limit fruit handling and removal away from the parent plants, while the territorial behaviour of birds at that time of the year reduces the potential distances of seed dispersal.     

文昌鱼的实验室繁育及子二代获得

文昌鱼特殊的进化地位、简单的器官系统和终生透明的躯体等特征,使其很有希望成为一个新型实验室模式动物。要实现文昌鱼的模式动物化,实验室内全人工条件下繁殖是关键的第一步。为此,我们于2003年9月和2004年4月两次采集产于厦门海域的2种文昌鱼,开展实验室内养殖研究。经过3年多的持续实验室养殖,继2005年夏季于实验室内繁殖出子一代文昌鱼后,又在2006年夏季成功获得了这两种文昌鱼的子二代,初步实现文昌鱼在实验室内的全人工养殖。对子代文昌鱼养殖的初步观察发现,不同水温对生长发育速度有一定影响,提示有可能通过水温控制实现文昌鱼一年多次产卵的目的。目前这两种文昌鱼子二代幼体已完成变态,进入亚成体生长发育阶段,其体长分别已达14.6mm(日本文昌鱼Branchiostomajaponicum)和6.5mm(白氏文昌鱼B.belcheri)。     

A multi-species assessment of post-dispersal seed predation in the central Chilean Andes

BACKGROUND AND AIMS: Post-dispersal seed predation in alpine communities has received little attention despite evidence that seeds removed by granivores can decrease plant recruitment into ecosystems. Moreover, few studies have assessed the effects of removal of seeds of a range of species after dispersal on the seeds remaining in ecosystems. A comparison was made of the magnitude of seed removal by ants and birds of nine different shrubby-, herbaceous- and cushion-plant species in the central Chilean Andes in order to assess the interactions between birds, ants and wind, and the types of seeds. METHODS: A total of 324 soil-covered plates, each containing 50 seeds of one species, were placed in the field at an altitude of 2700 m and assigned to one of four treatments: control, exclusion of ants, birds, and both. The design also allowed the effects of wind to be assessed. Seed removal from plates was monitored over 20 d. KEY RESULTS: Mean accumulative seed removal by granivores averaged over all nine species combined was 25%. However, large differences between species were evident, with limited seed removal (3-11%) in three herbaceous species (Alstroemeria pallida, Sisyrinchium arenarium, Pozoa coriacea), moderate (18-33%) in five species, including a shrub (Chuquiraga oppositifolia), two herbs (Taraxacum officinale, Rhodophiala rhodolirion), and two cushion-plants (Laretia acaulis, Azorella monantha), and substantial (78%) in the shrub Anarthrophyllum cumingii. The magnitudes of losses caused by birds compared with ants did not differ for the majority of species, although removal by birds was greater than by ants in A. cumingii, and smaller for C. oppositifolia. CONCLUSIONS: Post-dispersal seed removal is shown to be an important cause of decreased potential plant species recruitment into alpine ecosystems. The substantial differences in the magnitude of seed losses to ants and birds demonstrate the need for evaluation of seed removal on a wide range of species in any given ecosystem.     

Genetic characterization of rhesus macaques (Macaca mulatta) in Nepal

Indian-origin rhesus macaques (Macaca mulatta) have long served as an animal model for the study of human disease and behavior. Given the current shortage of Indian-origin rhesus, many researchers have turned to rhesus macaques from China as a substitute. However, a number of studies have identified marked genetic differences between the Chinese and Indian animals. We investigated the genetic characteristics of a third rhesus population, the rhesus macaques of Nepal. Twenty-one rhesus macaques at the Swoyambhu Temple in Kathmandu, Nepal, were compared with more than 300 Indian- and Chinese-origin rhesus macaques. The sequence analyses of two mitochondrial DNA (mtDNA) loci, from the HVS I and 12 S rRNA regions, showed that the Nepali animals were more similar to Indian-origin than to Chinese-origin animals. The distribution of alleles at 24 short tandem repeat (STR) loci distributed across 17 chromosomes also showed greater similarity between the Nepali and Indian-origin animals. Finally, an analysis of seven major histocompatibility complex (MHC) alleles showed that the Nepali animals expressed Class I alleles that are common to Indian-origin animals, including Mamu-A*01. All of these analyses also revealed a low level of genetic diversity within this Nepali rhesus sample. We conclude that the rhesus macaques of Nepal more closely resemble rhesus macaques of Indian origin than those of Chinese origin. As such, the Nepali rhesus may offer an additional resource option for researchers who wish to maintain research protocols with animals that possess key genetic features characteristic of Indian-origin rhesus macaques.