Germ band retraction as a landmark in glucose metabolism during <Emphasis Type="Italic">Aedes aegypti</Emphasis> embryogenesis

Background  

The mosquito A. aegypti is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of A. aegypty life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during A. aegypti embryogenesis are unknown.     

大鼠心肌缺血再灌注损伤模型的实验研究

目的 制备一种新型的心肌急性缺血再灌注损伤模型,以探讨一种更符合临床实际需求的实验方法.方法 将20只雌性SD(Sprague-Dawley)大鼠随机分成2组(对照组、实验组),采用结扎主动脉根部引起心肌缺血5min再灌注30 min建立心肌急性缺血再灌注模型;通过应用透射电镜观察心肌细胞超微结构的改变,同时检测心肌组织匀浆丙二醛(Maleic Dialdehyde,MDA)含量、超氧化物歧化酶(Superoxide Dismutase,SOD)活力.结果 透射电镜下超微结构显示实验组较对照组明显加重了心肌组织结构和线粒体的损害;实验组心肌组织MDA明显高于对照组(P<0.01),而SOD明显低于对照组(P<0.01).结论 本实验成功建立了方法简便、易于操作、取材范围广泛的心肌缺血再灌注损伤模型,为心肌缺血再灌注损伤研究提供了一种更为可行的模型.     

Diagnosis, pathogenesis, and treatment prospects in cystic kidney disease

Cystic kidney diseases (CKDs) are a clinically and genetically heterogeneous group of disorders characterized by progressive fibrocystic renal and hepatobiliary changes. Recent findings have proven the cystogenic process to be compatible with cellular dedifferentiation, i. e. increased apoptosis and proliferation rates, altered protein sorting and secretory characteristics, as well as disorganization of the extracellular matrix. Compelling evidence suggests that cilia play a central pathogenic role and most cystic kidney disorders converge into a common pathogenic pathway. Recently, several promising trials have further extended our understanding of the pathophysiology of CKD and may have the potential for rational personalized therapies in future years. This review aims to summarize the current state of knowledge of the structure and function of proteins underlying polycystic kidney disease, to explore the clinical consequences of changes in respective genes, and to discuss potential therapeutic approaches.     

Distinct patterns of nitrate reductase activity in brown algae: light and ammonium sensitivity in Laminaria digitata is absent in Fucus species1

Fucus and Laminaria species, dominant seaweeds in the intertidal and subtidal zones of the temperate North Atlantic, experience tidal cycles that are not synchronized with light:dark (L:D) cycles. To investigate how nutrient assimilation is affected by light cycles, the activity of nitrate reductase (NR) was examined in thalli incubated in outdoor tanks with flowing seawater and natural L:D cycles. NR activity in Laminaria digitata (Huds.) Lamour. showed strong diel patterns with low activities in darkness and peak activities near midday. This diel pattern was controlled by light but not by a circadian rhythm. In contrast, there was no diel variation in NR activity in Fucus serratus L., F. vesiculosus (L.) Lamour., and F. spiralis L. either collected directly from the shore or maintained in the outdoor tanks. In laboratory cultures, transfer to continuous darkness suppressed NR activity in L. digitata, but not in F. vesiculosus; continuous light increased NR activity in L. digitata but decreased activity in F. vesiculosus. Furthermore, 4 d enrichment with ammonium (50 μmol · L^?1 pulses), resulted in NR activity declining by >80% in L. digitata, but no significant changes in F. serratus. Seasonal differences in maximum NR activity were present in both genera with activities highest in late winter and lowest in summer. This is the first report of NR activity in any alga that is not strongly regulated by light and ammonium. Because light and tidal emersion do not always coincide, Fucus species may have lost the regulation of NR by light that has been observed in other algae and higher plants.     

Determining Parameters of the Numerical Response

The numerical response, the change in specific growth rate with food concentration, is a fundamental component of many aquatic microbial studies. Accurately and precisely determining the parameters of this response is essential to obtain useful data for both aut- and synecological studies. In this work we emphasize four points that are often ignored in designing numerical response experiments: (1) the inclusion of subthreshold concentrations (i.e., where growth rate is negative) in the experimental design; (2) an appropriate allocation of effort, i.e., the superiority of choosing more individual prey concentrations rather than replicating fewer; (3) the potential superiority of replicating experiments rather than simply replicating treatment in a single experiment; and (4) the placement of most measurements near the lower end of the concentration gradient, well below the asymptote, possibly following a geometric progression. We illustrate the first point by examining a small subset of published data on planktonic oligotrich ciliates and then, using a Monte Carlo simulation, rigorously evaluate the experimental design, supporting the remaining points.     

EVOLUTION OF AN ARTIFICIAL SEAWATER MEDIUM: IMPROVEMENTS IN ENRICHED SEAWATER, ARTIFICIAL WATER OVER THE LAST TWO DECADES

Although most phycologists use natural seawater for culturing marine species, artificial media continue to play important roles in overcoming problems of supply and seasonal variability in the quality of natural seawater and also for experiments involving manipulation of micro- and macronutrients. Several artificial media have been developed over the last 90 years; enriched seawater, artificial water (ESAW) is among the more popular recipes. ESAW has the advantage of an ionic balance that is somewhat closer to that of normal seawater. The original paper compared the growth of 83 strains of microalgae in natural seawater (ESNW) versus ESAW and determined that 23% grew more poorly in the artificial water. Since 1980, however, the composition of ESAW, as used by the original authors, has changed considerably. In particular, the added forms of phosphate, iron, and silicate have been changed and the trace metal mixture has been altered to include nickel, molybdenum, and selenium. We tested whether these changes improved the ability of the artificial medium to grow previously difficult to grow phytoplankton species. To test this, we selected eight species that had been shown to grow better in ESNW than in ESAW and compared their growth again, using the currently used recipe with all the above modifications. For all but one species ( Apedinella spinifera ), growth rate and final yield was no different between the media but in one case ( Emiliania huxleyi ) was slightly higher in ESAW. No differences in cell morphology or volume were found in any case. We conclude that changes to the enrichment portion of the recipe have significantly improved this artificial seawater medium and that it can be used to grow an even wider range of coastal and open ocean species.