Accounting for phenology in the analysis of animal movement

The analysis of animal tracking data provides important scientific understanding and discovery in ecology. Observations of animal trajectories using telemetry devices provide researchers with information about the way animals interact with their environment and each other. For many species, specific geographical features in the landscape can have a strong effect on behavior. Such features may correspond to a single point (eg, dens or kill sites), or to higher dimensional subspaces (eg, rivers or lakes). Features may be relatively static in time (eg, coastlines or home‐range centers), or may be dynamic (eg, sea ice extent or areas of high‐quality forage for herbivores). We introduce a novel model for animal movement that incorporates active selection for dynamic features in a landscape. Our approach is motivated by the study of polar bear (Ursus maritimus) movement. During the sea ice melt season, polar bears spend much of their time on sea ice above shallow, biologically productive water where they hunt seals. The changing distribution and characteristics of sea ice throughout the year mean that the location of valuable habitat is constantly shifting. We develop a model for the movement of polar bears that accounts for the effect of this important landscape feature. We introduce a two‐stage procedure for approximate Bayesian inference that allows us to analyze over 300 000 observed locations of 186 polar bears from 2012 to 2016. We use our model to estimate a spatial boundary of interest to wildlife managers that separates two subpopulations of polar bears from the Beaufort and Chukchi seas.     

Relative male and female contributions to the supercooling point of their offspring in Microvelia reticulata (Heteroptera: Veliidae)

Cold hardiness is a key life history trait in temperate and polar ectothermic species, as it affects survival during overwintering, but its evolution is poorly understood. While many studies of cold hardiness in insects have shown differences between species, populations or developmental stages, data on the relative contribution of individual genotypes to cold hardiness are scarce and mainly limited to drosophilid fly species. We used a sib‐analysis (paternal half‐sib/full‐sib breeding design) to estimate the relative contributions of parental generation to the supercooling point (SCP) of the offspring of a heteropteran non‐model insect species, Microvelia reticulata (Heteroptera: Gerromorpha: Veliidae). We found that parent identity affected significantly SCP values of their offspring. Magnitudes of estimated sire and dam variance components were similar but the distributions of individual contributions to SCP differed between sires and dams, which points to sex‐specific genetic or parental effects on SCP in this species. The animal model failed to find a realistic estimate of heritability (h²) of SCP, suggesting that the underlying genetics of SCP in M. reticulata can not be characterized by purely additive effects.     

2016年动物胃肠道微生物组研究十大亮点成果

动物胃肠道微生物对生产性能提高具有重要的作用,因此营养、微生物组与生产表型的互作研究已经成为国际研究热点。综述了2016年动物胃肠道微生物组学研究取得的十项重要成果,这些成果通过组学方法,研究了瘤胃纤维分解菌和尿素分解菌的功能基因多样性,揭示了微生物群落与日粮营养素、宿主基因型、环境的互作关系,阐明了反刍动物生产表型相关的瘤胃微生物种类和功能;首次构建猪肠道微生物组参考基因集,解析猪全肠道黏膜微生物组成,阐明了猪增重相关肠道微生物种类。这十大亮点成果将为国内动物营养学家开展动物胃肠道微生物组学研究提供参考。     

Predicting evolutionary responses to selection on polyandry in the wild: additive genetic covariances with female extra-pair reproduction

The evolutionary forces that underlie polyandry, including extra-pair reproduction (EPR) by socially monogamous females, remain unclear. Selection on EPR and resulting evolution have rarely been explicitly estimated or predicted in wild populations, and evolutionary predictions are vulnerable to bias due to environmental covariances and correlated selection through unmeasured traits. However, evolutionary responses to (correlated) selection on any trait can be directly predicted as additive genetic covariances (cov_A) with appropriate components of relative fitness. I used comprehensive life-history, paternity and pedigree data from song sparrows (Melospiza melodia) to estimate cov_A between a female''s liability to produce extra-pair offspring and two specific fitness components: relative annual reproductive success (ARS) and survival to recruitment. All three traits showed non-zero additive genetic variance. Estimates of cov_A were positive, predicting evolution towards increased EPR, but 95% credible intervals overlapped zero. There was therefore no conclusive prediction of evolutionary change in EPR due to (correlated) selection through female ARS or recruitment. Negative environmental covariance between EPR and ARS would have impeded evolutionary prediction from phenotypic selection differentials. These analyses demonstrate an explicit quantitative genetic approach to predicting evolutionary responses to components of (correlated) selection on EPR that should be unbiased by environmental covariances and unmeasured traits.     

膳食脂肪、肠道微生物与宿主健康的研究进展

作为三大主要营养物质之一,膳食脂肪为人体提供能量和营养。膳食脂肪摄入不当会破坏肠道微生物的稳态,影响宿主的代谢状况,增加慢性疾病发生的风险。建立疾病动物模型是研究肠道微生物与宿主健康的重要手段。文中综述了膳食脂质的数量和种类、肠道微生物和宿主代谢之间的相互作用及其可能的作用机制,阐述了基于不同的疾病动物模型,膳食脂质影响肠道微生物的结构和功能,以及对宿主代谢的调节,为深入了解膳食脂质、肠道微生态和宿主健康三者之间的关系提供了依据。     

互花米草入侵对土壤生态系统的影响

互花米草是全球海岸滩涂湿地生态系统最成功的入侵植物之一,对中国沿海湿地土壤生态系统也产生了重大影响.本文主要从入侵地土壤生态系统的结构组分(土壤微生物和土壤动物)与物质循环(土壤碳循环、氮循环、磷循环和重金属元素)两大方面,综述了近年来国内外互花米草入侵对沿海滩涂与河口地区土壤生态系统的影响.此外,本文还指出了未来互花米草的研究方向,包括加强互花米草对入侵地土壤微生物的影响的研究,整合互花米草对地上、地下资源竞争和生态过程影响的研究,以及互花米草在全球变化大背景下入侵动态预测.     

Recording Single Neurons' Action Potentials from Freely Moving Pigeons Across Three Stages of Learning

While the subject of learning has attracted immense interest from both behavioral and neural scientists, only relatively few investigators have observed single-neuron activity while animals are acquiring an operantly conditioned response, or when that response is extinguished. But even in these cases, observation periods usually encompass only a single stage of learning, i.e. acquisition or extinction, but not both (exceptions include protocols employing reversal learning; see Bingman et al.¹ for an example). However, acquisition and extinction entail different learning mechanisms and are therefore expected to be accompanied by different types and/or loci of neural plasticity.Accordingly, we developed a behavioral paradigm which institutes three stages of learning in a single behavioral session and which is well suited for the simultaneous recording of single neurons'' action potentials. Animals are trained on a single-interval forced choice task which requires mapping each of two possible choice responses to the presentation of different novel visual stimuli (acquisition). After having reached a predefined performance criterion, one of the two choice responses is no longer reinforced (extinction). Following a certain decrement in performance level, correct responses are reinforced again (reacquisition). By using a new set of stimuli in every session, animals can undergo the acquisition-extinction-reacquisition process repeatedly. Because all three stages of learning occur in a single behavioral session, the paradigm is ideal for the simultaneous observation of the spiking output of multiple single neurons. We use pigeons as model systems, but the task can easily be adapted to any other species capable of conditioned discrimination learning.     

Efficient adenoviral-mediated gene delivery into porcine mesenchymal stem cells

Mesenchymal stem cell (MSC) mediated gene therapy research has been conducted predominantly on rodents. Appropriate large animal models may provide additional safety and efficacy information prior to human clinical trials. The objectives of this study were: (a) to optimize adenoviral transduction efficiency of porcine bone marrow MSCs using a commercial polyamine-based transfection reagent (GeneJammer, Stratagene, La Jolla, CA), and (b) to determine whether transduced MSCs retain the ability to differentiate into mesodermal lineages. Porcine MSCs (pMSCs) were infected under varying conditions, with replication-defective adenoviral vectors carrying the GFP gene and GFP expression analyzed. Transduced cells were induced to differentiate in vitro into adipogenic, chondrogenic, and osteogenic lineages. We observed a 5.5-fold increase in the percentage of GFP-expressing pMSCs when adenovirus type 5 carrying the adenovirus type 35 fiber (Ad5F35eGFP) was used in conjunction with GeneJammer. Transduction of pMSCs at 10.3-13.8 MOI (1,500-2,000 vp/cell) in the presence of Gene Jammer yielded the highest percentage of GFP-expressing cells ( approximately 90%) without affecting cell viability. A similar positive effect was detected when pMSCs were infected with an Ad5eGFP vector. Presence of fetal bovine serum (FBS) during adenoviral transduction enhanced vector-encoded transgene expression in both GeneJammer-treated and control groups. pMSCs transduced with adenovirus vector in the presence of GeneJammer underwent lipogenic, chondrogenic, and osteogenic differentiation. Addition of GeneJammer during adenoviral infection of pMSCs can revert the poor transduction efficiency of pMSCs while retaining their pluripotent differentiation capacity. GeneJammer-enhanced transduction will facilitate the use of adenoviral vectors in MSC-mediated gene therapy models and therapies.     

几种椎间盘退变动物模型的建立和应用

椎间盘退变是一种年龄相关的退行性疾病,是引起下腰痛的主要因素,严重影响病人的生活质量,并显著增加家庭的经济负担。目前,缺少椎间盘退变的有效干预和治疗手段,部分原因是其发病机制尚未阐明。椎间盘退变动物模型的构建对于阐明该疾病的病理机制至关重要。椎间盘退变是一个复杂的过程,受机械应力、结构损伤、生物化学与基因表达等多种因素的影响。本文总结了应用异常机械应力、结构损伤、生物化学或化学诱导和基因敲除等方式构建的椎间盘退变动物模型。生物力学是维持椎间盘稳态的重要因素,异常的机械应力会导致椎间盘退变。同时,椎间盘退变常伴随结构性损伤,椎间盘结构破坏也会导致椎间盘发生退变。此外,生物化学或化学诱导和关键基因敲除也会导致椎间盘退变。本文按照造成异常机械应力的因素将机械应力模型分为加压模型和失稳模型;按照椎间盘结构将结构损伤模型分为髓核与纤维环损伤模型和软骨终板损伤模型。总结了生物化学或化学诱导模型以及新型的基因敲除模型。讨论了不同类型椎间盘退变动物模型的可能应用和局限性。