Conversion of the chill susceptible fruit fly larva (Drosophila melanogaster) to a freeze tolerant organism

Among vertebrates, only a few species of amphibians and reptiles tolerate the formation of ice crystals in their body fluids. Freeze tolerance is much more widespread in invertebrates, especially in overwintering insects. Evolutionary adaptations for freeze tolerance are considered to be highly complex. Here we show that surprisingly simple laboratory manipulations can change the chill susceptible insect to the freeze tolerant one. Larvae of Drosophila melanogaster, a fruit fly of tropical origin with a weak innate capacity to tolerate mild chilling, can survive when approximately 50% of their body water freezes. To achieve this goal, synergy of two fundamental prerequisites is required: (i) shutdown of larval development by exposing larvae to low temperatures (dormancy) and (ii) incorporating the free amino acid proline in tissues by feeding larvae a proline-augmented diet (cryopreservation).     

Unifying the spatial epidemiology and molecular evolution of emerging epidemics

We introduce a conceptual bridge between the previously unlinked fields of phylogenetics and mathematical spatial ecology, which enables the spatial parameters of an emerging epidemic to be directly estimated from sampled pathogen genome sequences. By using phylogenetic history to correct for spatial autocorrelation, we illustrate how a fundamental spatial variable, the diffusion coefficient, can be estimated using robust nonparametric statistics, and how heterogeneity in dispersal can be readily quantified. We apply this framework to the spread of the West Nile virus across North America, an important recent instance of spatial invasion by an emerging infectious disease. We demonstrate that the dispersal of West Nile virus is greater and far more variable than previously measured, such that its dissemination was critically determined by rare, long-range movements that are unlikely to be discerned during field observations. Our results indicate that, by ignoring this heterogeneity, previous models of the epidemic have substantially overestimated its basic reproductive number. More generally, our approach demonstrates that easily obtainable genetic data can be used to measure the spatial dynamics of natural populations that are otherwise difficult or costly to quantify.     

Bone morphogenetic protein- and mating-dependent secretory cell growth and migration in the Drosophila accessory gland

The paired male accessory glands of Drosophila melanogaster enhance sperm function, stimulate egg production, and reduce female receptivity to other males by releasing a complex mixture of glycoproteins from a secretory epithelium into seminal fluid. A small subpopulation of about 40 specialized secretory cells, called secondary cells, resides at the distal tip of each gland. We show that these cells grow via mechanisms promoted by mating. If aging males mate repeatedly, a subset of these cells delaminates from and migrates along the apical surface of the glandular epithelium toward the proximal end of the gland. Remarkably, these secretory cells can transfer to females with sperm during mating. The frequency of this event increases with age, so that more than 50% of triple-mated, 18-d-old males transfer secondary cells to females. Bone morphogenetic protein signaling specifically in secondary cells is needed to drive all of these processes and is required for the accessory gland to produce its normal effects on female postmating behavior in multiply mated males. We conclude that secondary cells are secretory cells with unusual migratory properties that can allow them to be transferred to females, and that these properties are a consequence of signaling that is required for secondary cells to maintain their normal reproductive functions as males age and mate.     

Evolutionary Anatomy and Phyletic Implication of the Extrinsic Cardiac Nervous System in the Philippine Tarsier (Tarsius syrichta,Primates) in Comparisons With Strepsirrhines and New World Monkeys

To provide information on evolutionary morphological differences and similarities between Tarsiformes (tarsiers) and other primates (Strepsirrhini and Platyrrhini), we examined the previously undescribed extrinsic cardiac nervous system (ECNS) and surrounding structures in three Philippine tarsiers (Tarsius syrichta). We found that the complicated ECNS morphology shows little variation in contrast to significant anatomical diversity of the surrounding somatic structures in tarsiers as reported in our previous primate studies. Further, our comparative morphological data on the ECNS show the following aspects of evolutionary anatomical significance; (1) the traits of the general relationship between the superior cervical ganglion and the spinal nerves are common to the Tarsii and Strepsirrhini, (2) the traits of the general composition of the cervicothoracic ganglion, its communicating branches to spinal nerves, and its cardiac nerve are common to the Tarsii and Platyrrhini, and (3) the traits of the general relationship between the middle cervical ganglion and the spinal nerves and its cardiac nerve are common among Strepsirrhini, Tarsii, and Platyrrhini. Therefore, the general anatomical characteristics of the ECNS in tarsiers retain a primitive state for some traits and exhibit a derived state for others. These characteristics of the ECNS also reflect an evolutionary history without the modification and specialization as seen in the surrounding somatic structures. It may play a key role in unifying future studies on molecular phylogeny and updating evolutionary anatomical information. Anat Rec, 296:798–806, 2013. © 2013 Wiley Periodicals, Inc.     

金铁锁叶绿体基因组序列及其系统发育分析

目的解析金铁锁叶绿体基因组结构和确定其在石竹科的系统位置。方法基于二代测序技术IlluminaHiseq平台,对金铁锁叶绿体基因组进行测序,使用生物信息学分析软件进行组装和注释,并以苋科植物千穗谷为外类群,通过RAxM L 8.2.11软件构建ML系统发育树,分析石竹科属间的亲缘关系。结果金铁锁叶绿体基因组总长为153977bp。LSC和SSC区被2个反向重复区域IRs隔开,其大小分别为84 385、17 526、26 033 bp。除去重复后,共编码109个基因,包含75个PCGs,30个tR NA和4个rR NA基因。总的CG含量为36.5%,IR区(42.4%)GC含量明显高于LSC(34.2%)和SSC(30.1%)区。在系统进化树中,金铁锁与长萼瞿麦互为姊妹类群,且各节点的支持率较高,能够清晰反映属间的亲缘关系。结论本研究对金铁锁叶绿体基因组结构进行了解析,并探讨了石竹科属间系统发育关系,为金铁锁种质资源综合评价、系统进化等研究提供有效的科学数据。     

RNA‐dependent RNA polymerase: Addressing Zika outbreak by a phylogeny‐based drug target study

Since the first major outbreak of Zika virus (ZIKV) in 2007, ZIKV is spreading explosively through South and Central America, and recent reports in highly populated developing countries alarm the possibility of a more catastrophic outbreak. ZIKV infection in pregnant women leads to embryonic microcephaly and Guillain–Barré syndrome in adults. At present, there is limited understanding of the infectious mechanism, and no approved therapy has been reported. Despite the withdrawal of public health emergency, the WHO still considers the ZIKV as a highly significant and long‐term public health challenge that the situation has to be addressed rapidly. Non‐structural protein 5 is essential for capping and replication of viral RNA and comprises a methyltransferase and RNA‐dependent RNA polymerase (RdRp) domain. We used molecular modeling to obtain the structure of ZIKV RdRp, and by molecular docking and phylogeny analysis, we here demonstrate the potential sites for drug screening. Two metal binding sites and an NS3‐interacting region in ZIKV RdRp are demonstrated as potential drug screening sites. The docked structures reveal a remarkable degree of conservation at the substrate binding site and the potential drug screening sites. A phylogeny‐based approach is provided for an emergency preparedness, where similar class of ligands could target phylogenetically related proteins.