Anthrax in animals

Anthrax is the archetype zoonosis; no other infectious disease affects such a wide range of species, including humans, although most susceptible are herbivorous mammals. Although the disease appears to have been recognized for centuries, it has yet to be established scientifically how animals contract it. While primarily a disease of warmer regions, it has long been spread to cooler zones through the trade of infected animals or contaminated animal products. Today it is still endemic in many countries of Africa and Asia and non-endemic countries must remain alert to the possibility of imports from such endemic areas resulting in outbreaks in their own livestock. The epidemiology of anthrax is becoming understood better with new systems coming on stream for distinguishing different genotypes and this is covered in detail. Clinical signs and pathology in animals are described.     

Clostridium difficile in young farm animals and slaughter animals in Belgium

Faecal carriage of Clostridium difficile in healthy animals has been reported recently, especially in piglets and calves. However there is limited data about carriage in animals just prior to slaughter in Europe. The main objective of this study was to determine the presence of C. difficile in pigs and cattle at the slaughterhouse. C. difficile was isolated in 6.9% of the cattle at the slaughterhouse. None of the pig slaughter samples were positive for C. difficile after an enrichment time of 72 h. For complementary data, a short study was conducted in piglets and calves at farms. C. difficile was more prevalent in piglets (78.3%) than in calves (22.2%) on the farms. Regarding the piglet samples, 27.8% of the positive samples were detected without enrichment of stools. The PCR ribotype 078 was predominant in farm animals. Samples isolated from slaughter cattle presented the widest range in PCR-ribotype variety, and the most prevalent PCR ribotype was 118a UCL. The results of this study confirm that C. difficile is present in slaughter animals in Belgium with a large percentage of toxigenic strains also commonly found in humans.     

Determinants of maturation in animals

Maturation is a critical transition in the life cycle. Recent models have used retrospective analyses of patterns of variation in age and size at maturity in an attempt to understand the mechanisms responsible for generating phenotypic variation in maturation. Empirical work has revealed greater complexity in the biology of maturation than has been incorporated in current models, and has cast doubt on some of the assumptions and conclusions of the models. Recent insights from experimental work, coupled with theoretical advances for the analysis of growth, size and other complex characters, have great potential to elucidate evolution of maturation and how adaptive maturation phenotypes are achieved by real organisms.     

Photosynthetic symbioses in animals

Animals acquire photosynthetically-fixed carbon by forming symbioseswith algae and cyanobacteria. These associations are widespreadin the phyla Porifera (sponges) and Cnidaria (corals, sea anemonesetc.) but otherwise uncommon or absent from animal phyla. Itis suggested that one factor contributing to the distributionof animal symbioses is the morphologically-simple body planof the Porifera and Cnidaria with a large surface area:volumerelationship well-suited to light capture by symbiotic algaein their tissues. Photosynthetic products are released fromliving symbiont cells to the animal host at substantial rates.Research with algal cells freshly isolated from the symbiosessuggests that low molecular weight compounds (e.g. maltose,glycerol) are the major release products but further researchis required to assess the relevance of these results to thealgae in the intact symbiosis. Photosynthesis also poses risksfor the animal because environmental perturbations, especiallyelevated temperature or irradiance, can lead to the productionof reactive oxygen species, damage to membranes and proteins,and ‘bleaching’, including breakdown of the symbiosis.The contribution of non-photochemical quenching and membranelipid composition of the algae to bleaching susceptibility isassessed. More generally, the development of genomic techniquesto help understand the processes underlying the function andbreakdown of function in photosynthetic symbioses is advocated. Key words: Bleaching, Chlorella, Cnidaria, coral, metabolite profiling, nutrient release, photosynthesis, Symbiodinium, symbiosis, symbiotic algae     

动物使用工具

提出了使用工具的定义,介绍了各种动物,特别是灵长动物使用工具的情况,并讨论了使用工具的起源和在个体发育过程中使用工具技能的改进和提高。     

动物的捕食行为

简要介绍了捕食行为研究的一些主要方向,如猎物选择、食物贮藏、捕食喂幼和捕食的节律性等,还讨论了动物的搜寻和捕食策略以及攻击方式等。     

Intercellular channels in animals

Gap junctions are considered to serve a similar function in all multicellular animals (Metazoa). Two unrelated protein families are involved in this function: connexins, which are found only in chordates, and pannexins, which are present in the genomes of both chordates and invertebrates. Recent sequence data from different organisms show important exceptions to this simplified scheme. It looks as if Chordate lancelet has only pannexins and no connexins in its genome. New data indicate that some metazoans have neither connexins nor pannexins and use other unidentified proteins to form gap junctions.     

Inbreeding avoidance in animals

The phenomenon of inbreeding depression is well documented and behavioral adaptations for inbreeding avoidance have been described. However, there is debate over whether inbreeding depression is always an important selective force on behavior. Here, we summarize recent evidence for inbreeding depression under natural conditions, review inbreeding avoidance mechanisms, and discuss how these are influenced by social structure. We also examine the idea that animals have evolved mechanisms to avoid outbreeding.     

动物的顿悟学习行为

顿悟是动物比较高级的一种学习类型,介绍了顿悟学习的特点以及顿悟学习与其他学习类型的区别,并以黑猩猩为例介绍了顿悟学习的一些经典事例,最后还介绍了学习集的基本概念。     

Skeletal loading in animals

A number of in vivo skeletal loading models have been developed to test specific hypotheses addressing the key mechanical and biochemical signals involved in bone's adaptive response to loading. Exercise protocols, osteotomy procedures, loading of surgically implanted pins, and force application through the soft tissues are common approaches to alter the mechanical environment of a bone. Although each animal overload model has a number of assets and limitations, models employing extrinsic forces allow greater control of the mechanical environment. Sham controls, for both surgical intervention (when performed) and loading, are required to unequivocally demonstrate that responses to loading are mechanically adaptive. Collectively, extrinsic loading models have fostered a greater understanding of the mechanical signals important for stimulating bone cells, and highlighted the roles of key signaling molecules in the adaptive response.