Dose and host characteristics influence virulence of ranavirus infections

Parasites play a prominent role in the ecology, evolution, and more recently, conservation of many organisms. For example, emerging infectious diseases, including a group of lethal ranaviruses, are associated with the declines and extinctions of amphibians around the world. An increasingly important basic and applied question is: what controls parasite virulence? We used a dose-response experiment with three laboratory-bred clutches of tiger salamander larvae (Ambystoma tigrinum) to test how the size of inoculum and host genetic factors influence the dynamics and outcome of ranavirus infections. We found that infection rates increased with dose and were strongly affected by clutch identity and host life history stage. Case mortality increased with dose of inoculum, but was unaffected by host characteristics. Average survival time decreased with dose and differed among clutches, but this was largely due to differences in the time to onset of symptoms. Overall, our results suggest that dose of inoculum and host characteristics (life history stage and genetic background) influence the establishment and early virus replication, and therefore the virulence of ranavirus infections.     

Indian Science for Indian Tigers?: Conservation Biology and the Question of Cultural Values

The implementation of Project Tiger in India, 1973–1974, was justly hailed as a triumph of international environmental advocacy. It occurred as a growing number of conservation-oriented biologists were beginning to argue forcefully for scientifically managed conservation of species and ecosystems – the same scientists who would, by the mid-1980s, call themselves conservation biologists. Although India accepted international funds to implement Project Tiger, it strictly limited research posts to Government of India Foresters, against the protests of Indian and US biologists who hoped to conduct the scientific studies that would lead to better management and thus more effective conservation of the tiger. The foresters were not trained to conduct research, and in fact did not produce any of significance for the first 15 years of Project Tiger’s existence. The failure of biologists to gain access to India’s tigers in the 1970s was caused by many factors, but not least among them was a history of disdain among conservation-oriented biologists for government officials managing reserves, and the local politics of conservation. Project Tiger, then, serves as a case study for the discussion of the intersection of conservation biology with non-scientific concerns, including nationalism and the desire of the Indian government to more completely control its land.¹I would like to thank the participants in the 2003 Southwest Colloquium for the Life Sciences for their constructive comments on an earlier version of this paper, as well as the two unusually helpful (anonymous) reviewers.     

虎物种特异性鉴定的 PCR 方法研究

为了建立可对虎DNA 进行特异性检测的PCR 方法, 应用在野外调查中获得的虎疑似样品和保护执法工作中难以检查辨认的虎产品进行物种鉴定, 从Genbank 数据库下载5 个虎亚种及其它6 种猫科动物和6 种鹿科动物的mtDNA 细胞色素b 基因序列, 并用Wdnasis (V2.5) 软件对上述不同动物的该基因碱基序列进行比较。在此基础上, 综合考虑了设计引物的基本原则, 选择了虎与其它动物碱基序列上差异位点较多的两个片段, 设计出PCR 引物(引物1、2) 。用该对引物分别对从东北虎、华南虎及8 种猫科动物和6 种非猫科动物的肌肉、脏器组织、皮或毛发中提取的DNA 进行PCR (聚合酶链反应) 扩增。结果表明, 所设计的引物对虎DNA 具有特异性,从而达到了对该物种进行特异性检测鉴定的目的。     

“筋骨并重”思想指导下的推拿手法联合颈夹脊穴龙虎交战针法治疗神经根型颈椎病的临床研究

摘要 目的：探讨“筋骨并重”思想指导下的推拿手法联合颈夹脊穴龙虎交战针法治疗神经根型颈椎病（CSR）的治疗效果。方法：选取2020年1月到2021年5月期间在东莞市中医院针灸科接受诊治的CSR患者108例，参照随机数字表法分成对照组与观察组，各54例。对照组接受常规治疗、“筋骨并重”思想指导下的推拿手法治疗，观察组在对照组的基础上联合颈夹脊穴龙虎交战针法治疗，两组均治疗2周。对比两组疗效、中医证候总积分、视觉模拟评分法（VAS）、颈椎病临床评价量表（CASCS）评分、颈部生物学相关参数及血液流变学。结果：观察组的临床总有效率为94.44%（51/54），高于对照组的74.07%（40/54），差异有统计学意义（P<0.05）。两组治疗2周后中医证候总积分、VAS评分下降，且观察组较对照组低；CASCS评分升高，且观察组高于对照组（P<0.05）。两组治疗2周后左旋转、右旋转颈功能活动度和前屈、后伸颈部肌力升高，且观察组高于对照组（P<0.05）。两组治疗2周后全血黏度高切、纤维蛋白原、血浆黏度、全血黏度低切下降，且观察组低于对照组（P<0.05）。结论：“筋骨并重”思想指导下的推拿手法联合颈夹脊穴龙虎交战针法治疗CSR患者，可有效改善其临床症状，减轻疼痛，恢复颈部脊椎功能，改善血液流变学，疗效确切。     

Habitability of Enceladus: Planetary Conditions for Life

The prolific activity and presence of a plume on Saturn's tiny moon Enceladus offers us a unique opportunity to sample the interior composition of an icy satellite, and to look for interesting chemistry and possible signs of life. Based on studies of the potential habitability of Jupiter's moon Europa, icy satellite oceans can be habitable if they are chemically mixed with the overlying ice shell on Myr time scales. We hypothesize that Enceladus' plume, tectonic processes, and possible liquid water ocean may create a complete and sustainable geochemical cycle that may allow it to support life. We discuss evidence for surface/ocean material exchange on Enceladus based on the amounts of silicate dust material present in the Enceladus' plume particles. Microphysical cloud modeling of Enceladus' plume shows that the particles originate from a region of Enceladus' near surface where the temperature exceeds 190 K. This could be consistent with a shear-heating origin of Enceladus' tiger stripes, which would indicate extremely high temperatures ( approximately 250-273 K) in the subsurface shear fault zone, leading to the generation of subsurface liquid water, chemical equilibration between surface and subsurface ices, and crustal recycling on a time scale of 1 to 5 Myr. Alternatively, if the tiger stripes form in a mid-ocean-ridge-type mechanism, a half-spreading rate of 1 m/year is consistent with the observed regional heat flux of 250 mW m(-2) and recycling of south polar terrain crust on a 1 to 5 Myr time scale as well.     

Are we doomed to repeat history? A model of the past using tiger beetles (Coleoptera: Cicindelidae) and conservation biology to anticipate the future

Studies of conservation biology involving tiger beetles have become increasingly common in the last 15 years. Governments and NGOs in several countries have considered tiger beetles in making policy decisions of national conservation efforts and have found tiger beetles useful organisms for arguing broad conservation issues. We trace the evolution of the relationship between tiger beetle studies and conservation biology and propose that this history may in itself provide a model for anticipating developments and improvements in the ability of conservation biology to find effective goals, gather appropriate data, and better communicate generalizations to non-scientific decision makers, the public, and other scientists. According to the General Continuum of Scientific Perspectives on Nature model, earliest biological studies begin with natural history and concentrate on observations in the field and specimen collecting, followed by observing and measuring in the field, manipulations in the field, observations and manipulations in the laboratory, and finally enter theoretical science including systems analysis and mathematical models. Using a balance of historical and analytical approaches, we tested the model using scientific studies of tiger beetles (Coleoptera: Cicindelidae) and the field of conservation biology. Conservation biology and tiger beetle studies follow the historical model, but the results for conservation biology also suggest a more complex model of simultaneous parallel developments. We use these results to anticipate ways to better meet goals in conservation biology, such as actively involving amateurs, avoiding exclusion of the public, and improving language and style in scientific communication. CXLV, Studies of Tiger Beetles