新城疫病毒某水禽分离株经鸡体传代后由非致病型转变为速发型的研究

最近，一株无毒力的新城疫病毒（NDV）在鸡体内繁殖时，变成了强毒株，但致今尚未能证实，经鸡体传代的野生水禽新城疫病毒是否也具有变成速发型毒株的能力，为了通过实验证明从水禽中分离的非致病型NDV可以转变为速发型病毒，我们通过在鸡体内传播鹅源性无毒力株，经气囊接种连续传代9次，随后再在鸡脑内传代5次，结果显示，该病毒的毒力变得很强，致死率可达100%，通过致病性试验证实，其具有典型的速发型病毒特征；融合蛋白裂解位点的序列分析表明，原始的分离株含有无毒力型毒株共有的裂解序列；E-R-Q-E-R/L，而通过鸡体反复传代后，该序列变为致癞 性毒株共有的序列：K-R-Q-K-R/F，这些结果表明，野生水禽中自然存在的无毒力毒株，具有无毒力株相应的序列，但当其在鸡群中传播时，则具有变成高致病性病毒的能力，同时研究表明，鸡体提供了该病毒从非致病型向致病型转变的选择机制。     

Numerical simulation of the migration and distribution of diamond squid (Thysanoteuthis rhombus) in the southwest Sea of Japan

To elucidate the effects of hydrographic conditions on the migration and distribution of diamond squid ( Thysanoteuthis rhombus ) in the Sea of Japan, two numerical experiments were conducted using a Lagrangian particle-tracking model. First, Lagrangian simulations with different horizontal swimming speeds were conducted in the area off the San-in coast, the southwest Sea of Japan. The comparison results of simulations and experimental tagging records from 2003 suggest that horizontal movement of diamond squid over a few days is influenced by individual swimming, but long-term migration over more than about 10 days is dependent on the ambient current field. Secondly, further Lagrangian simulations with biological processes, forced by different hydrographic conditions in 2003–2005, were conducted. Temporal variations in distributions and sizes calculated by the model corresponded approximately to those of catch data. A large number of particles simulating squid were distributed over the nearshore region from the San-in coast to the Noto Peninsula during September–November every year. Differences in the migration route and distribution of particles among years were closely related to differences in hydrographic conditions such as the position of the main stream of the Tsushima Warm Current. Prediction of the catch off the San-in coast might be improved by considering hydrographic conditions in the southwest Sea of Japan.     

Effects of elevated pCO2 on the early development of the commercially important gastropod,Ezo abalone Haliotis discus hannai

We used an up‐to‐date, a high accuracy CO₂ manipulation system to investigate the sensitivity of organisms to CO₂ acidification, rearing marine calcifiers under elevated CO₂ in running water. We evaluated the effects of elevated partial pressures of carbon dioxide (pCO₂) in seawater on larvae of the commercially important marine gastropod Ezo abalone Haliotis discus hannai. In larval Ezo abalone, no effect of exposure to <1100 μatm pCO₂ seawater was observed in fertilization, malformation, or mortality rates until 15 h after fertilization. However, compared to control larvae in seawater (450 or 500 μatm pCO₂), the fertilization rate and the hatching rate (15 h after fertilization) decreased with increased pCO₂ exposure (1650 and 2150 μatm pCO₂) and the malformation rate increased significantly, with the larval shell length being smaller 75 h after hatching. These results suggest that ocean acidification will potentially impact the marine population of Ezo abalone as a human food source in the future.