Inter-colony and sex differences in the effects of parental body condition and foraging effort on the brood growth of Adélie penguins

Among colonies with different foraging distances, central-place-foraging seabirds may change their foraging and reproductive efforts. We compared the body condition, meal frequency, and diving behavior of male and female Adélie penguins at two locations: Dumont d'Urville, where there was little sea ice and they foraged in open waters far from the colony; and Syowa, where there was heavy, fast sea ice and they foraged in ice cracks close to the colony. The parental mass decrease rate during the chick-rearing period was similar between colonies and between sexes. A large individual variation in meal frequency positively affected the brood growth rate, but daily underwater time did not. A weak but significant positive effect of body condition on brood growth rate was found only in males at Syowa. It was suggested that males work with better body condition than females. We propose the hypothesis that the regional difference in the distance to the feeding sites and the sex difference in body energy reserve might constrain the capacity to regulate reproductive effort.     

Enhanced immunodetection of cell-free synthesized erythropoietin under denaturing conditions

A monoclonal antibody produced by hydridoma cell line, ATCC HB8209, was used to detect and purify erythropoietin synthesized in a cell-free system. The antibody was raised against the N-terminal 20 residues of erythropoietin. It retained anti-erythropoietin activity in 6 M urea in which most of the cell-free synthesized erythropoietin became soluble and gave an enhanced activity of the antibody.     

Phenotypic flexibility of digestive morphology and physiology of the South American omnivorous rodent Akodon azarae (Rodentia: Sigmodontinae)

We have determined the occurrence of responses at different levels (morphological, physiological and biochemical) in the omnivorous rodent Akodon azarae upon cold acclimation (15 degrees C). A short-term enhancement in food consumption appeared to account for the maintenance of both mass and body composition. At the morphological level, the main response was an increase in the dimensions of small intestine, which constitutes the section of the gut where absorption and secretion take place. An increase in sucrase specific activity was only found in small intestine. Sucrose independent maltase activity was very low since 99.8% of total maltase activity was due to sucrase-isomaltase (SI) complex. Protease specific activities were not affected. The fact that resting metabolic rates determined at 15 and 23 degrees C were similar in cold acclimated animals suggests a change in lower critical temperature. In conclusion, our results show that A. azarae exhibits different strategies to support cold environment that could lead to an enhancement in digestion and absorption efficiency. Furthermore, this work suggests that low temperature is an independent cue of other environmental factors to trigger the strategies allowing the maintenance of body condition in A. azarae.     

Prevalence of agglutinating antibodies against<Emphasis Type="Italic"> Listeria monocytogenes</Emphasis> in chicks of the white stork (<Emphasis Type="Italic">Ciconia ciconia</Emphasis> Linnaeus, 1758) in Poland

In 2002 and 2003, blood samples from white stork (Ciconia ciconia) chicks were examined for the presence of antibodies against Listeria monocytogenes. Listeria antibodies were detected in 121 (59%) of 205 chick samples. The probability of Listeria antibodies being present increased with chick age; chicks detected with Listeria antibodies were in better condition than those without the bacterium.     

Sexually selected nest-building--Pomatoschistus minutus males build smaller nest-openings in the presence of sneaker males

Both natural selection and sexual selection may act on nest-building. We tested experimentally how different regimes of egg-predation and male-male competition influence nest-building before mating, using the marine fish sand goby, Pomatoschistus minutus. Males with sneaker males present built the smallest nest-openings, smaller than males held alone or with Pomatoschistus microps males (which may predate eggs and compete over nest-sites but not compete over fertilizations). Males with visual access to other nest-building males tended also to build smaller openings than males held alone or with P. microps. Males with egg-predators present built nests with openings not differing significantly from any other treatment. Our results indicate that the small nest-openings found in the sneaker male treatment are sexually selected through protection against sneaking or by female choice. Across treatments, time span before a male started to build his nest also explained variation in nest-opening width; males starting late built larger nest-openings.     

A study of prey-predator relations for mammals

In this paper, we present a prey-predator nonlinear model for mammals, consisting of large- and small-size prey species with group defence, in a partially protected habitat. If the prey size is small, then it is more prone to the predator at higher densities. Conversely, large prey size at higher densities tend to develop group defence. Therefore, the predator will be attracted towards that area where prey are less in number. A new physical constant has been introduced into the radiation-type condition on that part of the boundary where interaction between prey and predator takes place. This constant allows us to efficiently model group defence capabilities of the herds and its numerical values have to be determined for different pairs of prey-predator species from field observations. A way of measuring the constants involved in the model is suggested. Numerical results are provided and thoroughly discussed for a habitat of circular shape. The obtained results show that in the region away from the protected area, the density of large-size prey species is higher than that of small-size prey species, a fact that is in accordance with observations.     

Size-dependent selection on arrival times in sticklebacks: why small males arrive first

Abstract Studies on arrival time to breeding areas show that high-quality males usually arrive first and gain the highest reproductive success. This is generally assumed to be due to phenotype-dependent costs and benefits of early arrival. We show that the opposite arrival order can occur, probably due to selection on poor-quality males to increase their chances of reproduction. In a fish species, the threespine stickleback, Gasterosteus aculeatus , small males arrived before larger males at the breeding grounds. Early arrival was costly because predation risk was at its highest at the start of the season and early territory establishment was selected against, as demonstrated by selection coefficients for territory maintenance and hatching success. Large males probably postponed arrival until females were available to decrease predation risk costs and increase offspring production. An experimental study showed that a delay in arrival of large males does not decrease their probability of reproduction, because large males are able to take over nest sites from small males. Small males, on the other hand, are less likely to establish territories in competition with large males but can pay the costs of early arrival in exchange for the benefit of access to territories. Thus, whereas natural selection favors later arrival, sexual selection through competition for breeding territories favors early arrival in small, competitively inferior males. This results in the benefits of early arrival depending on the competitive ability of the male, which favors size-dependent optimal arrival times.     

Mutation and sexual selection: a test using barn swallows from Chernobyl

Abstract Secondary sexual characters have been hypothesized to be particularly susceptible to the deleterious effects of mutation because the expression of such characters is usually influenced by many more metabolic pathways than are ordinary morphological characters. We tested this hypothesis using the elevated mutation rates in the barn swallow ( Hirundo rustica ) of the Chernobyl region of Ukraine as a model system. A great deal is known about the relative importance of different characters for male mating success in this species. The importance of phenotypic characters for male mating success was quantified based on a long-term study of a Danish breeding population, by expressing phenotypic differences between mated and unmated males as the difference between log-transformed mean values. For field samples from Ukraine we likewise expressed the difference in male phenotype between individuals living in a relatively uncontaminated area and individuals from the Chernobyl region as the difference between log-transformed mean values. The standardized difference in male phenotype between the two regions in Ukraine for the 41 different characters was strongly positively correlated with the standardized difference in male phenotype between mated and unmated males from Denmark. The standardized difference in male phenotype between the two regions in Ukraine was significantly positively associated with sexual size dimorphism. However, the standardized difference in male phenotype between mated and unmated males was a much better predictor of standardized difference in male phenotype between the two regions in Ukraine than was the standardized difference in sexual size dimorphism, expressed as the difference between log-transformed mean values for males and females. These findings are consistent with the hypothesis that traits most important for sexual selection are particularly susceptible to the effects of deleterious mutations.     

脂肪酶产生菌Candida rugosa产酶条件研究

脂肪酶(Lipase,EC3.1.1.3)是用来催化酯类化合物的分解、合成和酯交换的特殊酶,具有高度的化学选择性和立体异构性,它广泛应用于食品、轻纺、皮革、香料、化妆品、洗涤剂、有机合成、医药等领域.本世纪80年代,美国科学家发现酶在近无水的有机溶剂中不仅能保存其催化活力,而且还获得许多新的催化特征[1],此后,脂肪酶在非水相酶催化领域的研究和应用逐渐增多.