Assessing common bottlenose dolphin (Tursiops truncatus) population structure in Mississippi Sound and coastal waters of the north central Gulf of Mexico

1. Population structure of highly mobile marine organisms can be complex and difficult to study, but it is important to understand how populations partition themselves within their environment for accurate assessment of both natural and anthropogenic impacts and successful management. The 2010 Deepwater Horizon oil spill negatively impacted common bottlenose dolphins (Tursiops truncatus) within Mississippi Sound and the surrounding north central Gulf of Mexico (GOMx); however, little was known about their underlying population structure in these waters. Thus, it was unclear how many demographically independent populations were affected by the spill.
2. Common bottlenose dolphin samples were collected throughout inshore waters of Mississippi Sound and coastal waters of the north-central GOMx. Mitochondrial DNA control region sequence data and 19 nuclear microsatellite loci were analysed to determine how many populations are present and characterize their range throughout these waters.
3. Bayesian clustering and migration analyses identified two genetically distinct and demographically independent populations: one predominantly inhabiting Mississippi Sound and adjacent coastal waters, and a second population extending generally from offshore of Mobile Bay, Alabama, east along the Florida Panhandle. Neither of these populations align with the currently delineated management stocks previously used to estimate impacts from the oil spill on common bottlenose dolphins in this portion of the GOMx.
4. These results suggest that revisions may be necessary so that management stocks accurately represent the demographically independent populations present in these waters. Furthermore, better comprehension of underlying population structure will enhance impact assessments on common bottlenose dolphins and provide more appropriate baseline data to support future restoration and conservation objectives.

     

清华大学钟毅课题组阐明果蝇短期记忆遗忘机理

新获取的记忆如果未经强化记忆通常会很快遗忘,这种记忆遗忘被认为是由于新获取记忆本身的不稳定性或随后获取信息的干扰所造成的.近日,来自清华大学钟毅课题组的研究人员在这种短期记忆遗忘机理研究上取得重大进展,该研究认为这种快速遗忘是一种主动行为,用以抹掉旧的记忆腾出空间来存储新的记忆.相关研究结果于2010年2月19日发表在(Cell)杂志上,并被列为同期的特色文章(Featured Article).     

Interrelationships among height,lodging and yield in determinate and indeterminate soybeans

Summary Seventy-three determinate and 93 indeterminate random F₉ lines from a cross between determinate and indeterminate soybean [Glycine max (L.) Merr.] parents were evaluated for seed yield, mature plant height, and lodging. Regression analyses indicated that among the determinate lines, seed yield increased by 350 kg/ha and lodging score increased by 0.008 for every 10 cm increase in plant height. Among indeterminate lines seed yield increased by 112 kg/ha and lodging score by 0.3 for every 10 cm increase in plant height. The highest yielding indeterminate lines were tall and very susceptible to lodging. The tall determinate lines had the best combination of high seed yield and excellent lodging resistance.Cooperative Investigations of the Science and Education Administration, U.S. Department of Agriculture and the Purdue University Agricultural Experiment Station.     

Solar structure and terrestrial weather

If there is indeed an effect of the variable sun on the weather, the physical cause for it remains quite elusive (12). We should keep in mind the possibility that there may be several causes and several effects. The situation may change through the 11-year sunspot cycle and the 22-year solar magnetic cycle, as well as on longer time scales. Work is proceeding at a lively pace at the institutions mentioned in this article and at many others around the world. The Soviet Union has long had considerably more workers interested in this field than has any other country. A bilateral agreement between the Soviet Union and the United States has considerably increased the interactions between workers interested in this subject, including an exchange of extended visits between the two countries. A detailed knowledge of solar causes of geomagnetic activity is only now beginning to emerge after many years of scientific efforts. This suggests that a possible successful solution to the sun-weather problem will require a similar magnitude of effort. We look forward with interest and optimism to the results of the next few years.     

Solar flare acceleration of solar wind: influence of active region magnetic field

The direction of the photospheric magnetic field at the site of a solar flare is a good predictor of whether the flare will accelerate solar wind plasma. If the field has a southward component, high-speed solar wind plasma is usually observed near the earth about 4 days later. If the field has a northward component, such high-speed solar wind is almost never observed. Southward-field flares may then be expected to have much larger terrestrial effects than northward flares.     

Effects of thermal stress and level of feed intake on portal plasma flow and net fluxes of metabolites in lactating Holstein cows

Six Holstein cows (averaging 475 kg body weight, 2.3 parities and 96 d in lactation) fitted with catheters in the hepatic portal vein, mesenteric vein and intercostalis posterior artery were exposed to treatments of thermal comfort environments with libitum or restricted (75% of ad libitum) DM intake and a thermal stress environment with ad libitum intake in two balanced 3 x 3 latin squares to evaluate effects of thermal stress on portal plasma flow and net fluxes of metabolites. Portal plasma flow was measured by administering a primed, continuous infusion of para-aminohippurate into a mesenteric vein and determining its concentration and dilution in portal vein plasma. Thermal stress treatment increased rectal temperatures and respiration rates. Dry matter intake decreased from thermal comfort ad libitum level (15.1 kg/d) to lower levels in thermal comfort restricted (11.5 kg/d) and thermal stress (11.1 kg/d) treatments. Portal plasma flow was related directly to level of DM intake, declining about 14% with thermal comfort restricted intake and thermal stress environment treatments compared with the thermal comfort restricted intake and thermal stress environment treatments compared with the thermal comfort ad libitum intake treatment. Net flux of alpha-amino N was reduced 20 and 35% by thermal comfort restricted intake and thermal stress treatments compared with the thermal comfort ad libitum intake treatment. Net fluxes of urea N, ammonia N and glucose were not affected by experimental treatments. A portion of the negative effects of thermal stress on milk production can be explained by decreased nutrient intake and decreased nutrient uptake by the portal-drained viscera of the cow.     

BOOK SHELF

Veterinary Virology, 2nd edition, FJ Fenner, EPJ Gibbs, FA Murphy, R Roitt, MJ Studded and DO White, Russia.     

Effect of colostrum deprivation of goat kids on the natural transmission of caprine retrovirus infection

An investigation was conducted to determine if depriving goat kids of colostrum and rearing them away from the herd would prevent transmission of caprine retrovirus infection. Twenty-four newborn goat kids were deprived of colostrum and reared on cow's milk away from their dams from an endemically infected goat herd. Twenty-three colostrum-deprived kids had no evidence of retrovirus infection at birth. One kid had sucked briefly and obtained some colostrum resulting in passive transfer of antibody but it did not develop evidence of infection. Nineteen showed no serological evidence of infection over the 370 days of the study. One colostrum-deprived, segregated goat was subsequently found to be infected and developed arthritis-synovitis. Three had doubtful positive response in one or 2 serological tests during the period but no evidence of infection in leucocyte co-cultures. Cells centrifuged from colostrum of infected goats were co-cultivated with foetal goat synovial membrane cultures. Caprine retrovirus was isolated from cells in the colostrum from the 3 goats examined.