Intra‐ and interspecific differences in nutrient recycling by European freshwater fish

1. We measured N and P excretion rates of 470 individuals belonging to 18 freshwater fish species widespread in Western Europe. We assessed the effect of body mass on excretion rates at both the intra‐ and interspecific levels. 2. The high variability in per capita N and P excretion rates was mainly determined by differences in body mass. The scaling coefficients of allometric relationships for both N and P excretion rates were significantly lower than 1 (mean ± SE, 0.95 ± 0.04 and 0.81 ± 0.05, respectively). 3. The slope of the allometric relationship between fish mass and nutrient excretion rate was significantly different among species. We did not detect any influence of phylogenetic conservatism on fish mass and on excretion rates. Further investigations are needed to understand the biological determinants of these differences. 4. This high intra‐ and interspecific variability in per capita excretion rates, coupled with differences in fish body mass, produce marked differences in biomass‐standardised excretion rates. These results thus indicate the necessity for further experimental and in situ investigations on the consequences of nutrient recycling by fish in freshwater ecosystems.     

Variability in responses to thermal stress in parasitoids

Abstract 1. To study phenotypic effects of stress, a stress is applied to cohorts of organisms with an increasing intensity. In the absence of mortality the response of traits will be a decreasing function of stress intensity because of increasing physiological costs. We call such decreasing functions type A responses. 2. However, when stress caused mortality, some studies have found that for high stress intensities, survivors performed as well as control individuals (type B responses). We proposed that type A responses are caused by the physiological cost of stress whereas type B responses are caused by a mixture of physiological costs and selection. 3. The present study exposed Aphidius picipes wasps to an increasing duration of cold storage (cold stress), and obtained variable responses as predicted when both physiological costs and selection of resistant individuals determine the outcome. 4. When cold storage of parasitoids for biological control is desirable, research should be carried out to find (i) the temperature regime and duration of storage and (ii) the least sensitive stage for storage to minimise losses from mortality and reduction of fitness of survivors. 5. Selection by cold stress as observed in the present study could result in rapid adaptation of populations exposed to such stress.     

腺嘌呤与氢化可的松大鼠肾阳虚模型造模方法比较

目的比较腺嘌呤诱导与氢化可的松诱导的SD大鼠肾阳虚模型的优劣,从而得到临床症状、生化指标更符合中医“肾阳虚”型的动物模型,以供科研、教学使用。方法雄性SD大鼠100只,随机分成正常组、腺嘌呤造模组及氢化可的松低剂量组、中剂量组、高剂量组各20只,造模成功后检测血肌酐（Scr）、尿素氮（BUN）、尿液中17-羟皮质类固醇（17-OH）和血浆中甲状腺激素（13、T4）、睾丸酮（T）、雌二醇（E2）及模型大鼠骨密度。结果无论从症状主证方面,还是客观指标方面（除骨密度外）,腺嘌呤诱导的SD大鼠肾阳虚型动物模型在生化指标研究方面均优于氢化可的松诱导组。结论腺嘌呤诱导的肾阳虚证SD大鼠模型在症状主证方面及其相关的生化研究方面优于氢化可的松组。     

Microsatellite markers from the Indian major carp species,Catla catla

The Indian major carp Catla catla is indigenous to the major river systems of Northern India, Pakistan and Bangladesh, and is an important contributor to aquaculture production in India and Bangladesh. Five polymorphic microsatellite loci, developed from Catla catla are described and their utility in other major carp and cyprinid species is tested.     

Heteroplasmy suggests paternal co-transmission of multiple genomes and pervasive reversion of maternally into paternally transmitted genomes of mussel (Mytilus) mitochondrial DNA

Marine mussels of the genus Mytilus have two types of mitochondrial DNA with separate paternal and maternal inheritance. Females are homoplasmic for an F genome that is transmitted to all offspring, whereas males are heteroplasmic for this F genome and for a highly diverged (> 20%) M genome that is transmitted only to sons. Here we provide phylogenetic evidence based on lrRNA sequence data that most of the paternal genomes in European M. trossulus have an introgressive female M. edulis origin and are nearly indistinguishable in sequence from F types of M. trossulus. This observation is best explained by the hypothesis that introgressed F type molecules have recently invaded the paternal route and have assumed the role of M molecules, then resetting to zero the time of sequence divergence between M and F lineages. European M. trossulus shows a high prevalence of males heteroplasmic for three different mitochondrial DNA types all having the same two paternal types and the same maternal type, consistent with paternal co-transmission of multiple genomes. Co-transmission of the same genomes must apparently operate uninterruptedly for several generations in spite of the very different evolutionary origin of the specific molecules that are transmitted paternally and maternally in European M. trossulus.     

Microsatellite marker based genetic linkage maps of Oreochromis aureus and O. niloticus (Cichlidae): extensive linkage group segment homologies revealed

Partial genetic linkage maps, based on microsatellite markers, were constructed for two tilapia species, Oreochromis aureus and Oreochromis niloticus using an interspecific backcross population. The linkage map for O. aureus comprised 28 markers on 10 linkage groups and covered 212.8 CM. Nine markers were mapped to four linkage groups on an O. niloticus female linkage map covering 40.6 CM. Results revealed a high degree of conservation of synteny between the linkage groups defined in O. aureus and the previously published genetic linkage map of O. niloticus.     

Bronchial epithelial cell growth regulation in fibroblast cocultures: the role of hepatocyte growth factor

Proliferation of bronchial epithelial cells is an important biological process in physiological conditions and various lung diseases. The objective of this study was to determine how bronchial fibroblasts influence bronchial epithelial cell proliferation. The proliferative activity in cocultures was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and direct cells counts. Concentration of cytokines was measured in cell culture supernatants by means of ELISA. In primary cell cocultures, fibroblasts or fibroblast-conditioned medium enhanced 1.85-fold the proliferation of primary bronchial epithelial cells (P < 0.02) compared with bronchial epithelial cells cultured alone. The proliferative activity in cocultures and in fibroblast-conditioned medium was reduced by neutralizing antibody to hepatocyte growth factor (HGF) and HGF receptor c-met. Neutralizing antibodies to FGF-7 and IGF-1 had no effect. Treatment of fibroblast-epithelial cocultures with anti-IL-6 and anti-TNF-alpha neutralizing antibodies and with indomethacin decreased production of HGF. These results indicate that cytokines and PGE(2) may indirectly mediate epithelial cell proliferation via the regulation of HGF in bronchial stromal cells and that HGF plays a crucial role in proinflammatory cytokine-induced proliferation in the experimental system studied.