Experience,but not distance,influences the recruitment precision in the stingless bee <Emphasis Type="Italic">Scaptotrigona mexicana</Emphasis>

Recruitment precision, i.e. the proportion of recruits that reach an advertised food source, is a crucial adaptation of social bees to their environment. Studies with honeybees showed that recruitment precision is not a fixed feature, but it may be enhanced by factors like experience and distance. However, little is known regarding the recruitment precision of stingless bees. Hence, in this study, we examined the effects of experience and spatial distance on the precision of the food communication system of the stingless bee Scaptotrigona mexicana. We conducted the experiments by training bees to a three-dimensional artificial patch at several distances from the colony. We recorded the choices of individual recruited foragers, either being newcomers (foragers without experience with the advertised food source) or experienced (foragers that had previously visited the feeder). We found that the average precision of newcomers (95.6 ± 2.61%) was significantly higher than that of experienced bees (80.2 ± 1.12%). While this might seem counter-intuitive on first sight, this “loss” of precision can be explained by the tendency of experienced recruits to explore nearby areas to find new rewarding food sources after they had initially learned the exact location of the food source. Increasing the distance from the colony had no significant effect on the precision of the foraging bees. Thus, our data show that experience, but not the distance of the food source, affected the patch precision of S. mexicana foragers.     

Rare royal families in honeybees, Apis mellifera

The queen is the dominant female in the honeybee colony, Apis mellifera, and controls reproduction. Queen larvae are selected by the workers and are fed a special diet (royal jelly), which determines caste. Because queens mate with many males a large number of subfamilies coexist in the colony. As a consequence, there is a considerable potential for conflict among the subfamilies over queen rearing. Here we show that honeybee queens are not reared at random but are preferentially reared from rare “royal” subfamilies, which have extremely low frequencies in the colony's worker force but a high frequency in the queens reared.     

Torpor and energetic consequences in free-ranging grey mouse lemurs (Microcebus murinus): a comparison of dry and wet forests

Many endotherms save energy during food and water shortage or unpredictable environment using controlled reductions in body temperature and metabolism called torpor. In this study, we measured energy metabolism and water turnover in free-ranging grey mouse lemurs Microcebus murinus (approximately 60 g) using doubly labelled water during the austral winter in the rain forest of southeastern Madagascar. We then compared patterns of thermal biology between grey mouse lemurs from the rain forest and a population from the dry forest. M. murinus from the rain forest, without a distinct dry season, entered daily torpor independent of ambient temperature (T _a). There were no differences in torpor occurrence, duration and depth between M. murinus from the rain and dry forest. Mouse lemurs using daily torpor reduced their energy expenditure by 11% in the rain forest and by 10.5% in the dry forest, respectively. There was no significant difference in the mean water flux rates of mouse lemurs remaining normothermic between populations of both sites. In contrast, mean water flux rate of individuals from the dry forest that used torpor was significantly lower than those from the rain forest. This study represents the first account of energy expenditure, water flux and skin temperature (T _sk) in free-ranging M. murinus from the rain forest. Our comparative findings suggest that water turnover and therefore water requirement during the austral winter months plays a more restricting role on grey mouse lemurs from the dry forest than on those from the rain forest.     

气相色谱/质谱法分析食品中的丙烯酰胺

要揭示烹调食物中有无丙烯酰胺,需对可疑食品进行检测。经典的方法是用水从食品中提取出丙烯酸胺,再将其转化成溴化衍生物。文章描述了这些衍生物的电子轰击和正离子化学电离响应和谱图。另外,还介绍了一种更直接、更简便的方法,包括丙烯酰胺提取和直接进样,并用正离子化学电离进行分析。这种监测方法快速、可靠,检测限低。     

Photoinduced reduction of divalent mercury in ice by organic matter

Reduction of divalent mercury and subsequent emission to the atmosphere has been identified as loss process from surface snow, but its mechanism and importance are still unclear. The amount of mercury that stays in the snow pack until spring is of significance, because during snow melt it may be released to the aquatic environment and enter the food web. Better knowledge of its fate in snow might further assist the interpretation of ice core data as paleo-archive. Experiments were performed under well-controlled laboratory conditions in a coated wall flow tube at atmospheric pressure and irradiated with light between 300 nm and 420 nm. Our results show that the presence of benzophenone and of oxalic acid significantly enhances the release of mercury from the ice film during irradiation, whereas humic acid is less potent to promote the reduction. Further it was found that oxygen or chloride, and acidic conditions lowered the photolytically induced mercury release in the presence of benzophenone, while the release got larger with increasing temperatures.     

Prenatal diagnosis of cleft lip and palate by ultrasound

Bilateral cleft lip and cleft palate can be diagnosed by ultrasonography prior to 20 weeks of pregnancy. The anomaly produces an abnormal facial profile and, on cross-section, the clefts in the maxilla are demonstrable. The method is illustrated by sonograms from a fetus in which the defect was diagnosed before trisomy 13 became known by karyotyping.