Iridophore development in wild-type and periodic albinoXenopus larvae

Summary Light microscopic studies of iridophore preparations from a^p mutantXenopus larvae revealed abnormalities in the morphology and size distribution of reflecting platelets; purine synthesis is normal. A pleiotropic effect of the a^p gene on melanoblasts and iridoblasts is proposed.     

Constructing dissimilarity measures

The paper addresses the problem of specifying differential weights for variables in the construction of a measure of dissimilarity. An assessor is required to provide subjective judgments of the pairwise dissimilarities within a training set of objects, and these dissimilarities are then modeled as a function of the recorded differences between the objects on each of the variables. The aim is to make explicit the relative importance that assessors attach to each of the variables, and thus obtain guidance on how these variables should be combined into a relevant dissimilarity matrix. The methodology is illustrated by application to some archaeological data.     

教育学习工具灵活和有效的瘦客户部署方式

Given today's dynamic and fast paced world of Information Technology(IT),it has become more challenging for an IT manager to provide students with the most flexible and innovative learning environment.The requirement to provide these facilities must be balanced against constraints such as capital spending within budgets,maintenance costs and staffing issues.This paper discusses how a server-centric IT solution,such as thin clients,is capable of meeting these demands in a more efficient manner particularly in relation to Financial Management,Infrastructure Management and Security Management.The flexibility and efficiency of server-centric technology as an education tool is overviewed as experienced by several departments within the Dublin Institute of Technology.     

DNA sequencing of a cytogenetically normal acute myeloid leukaemia genome

Acute myeloid leukaemia is a highly malignant haematopoietic tumour that affects about 13,000 adults in the United States each year. The treatment of this disease has changed little in the past two decades, because most of the genetic events that initiate the disease remain undiscovered. Whole-genome sequencing is now possible at a reasonable cost and timeframe to use this approach for the unbiased discovery of tumour-specific somatic mutations that alter the protein-coding genes. Here we present the results obtained from sequencing a typical acute myeloid leukaemia genome, and its matched normal counterpart obtained from the same patient's skin. We discovered ten genes with acquired mutations; two were previously described mutations that are thought to contribute to tumour progression, and eight were new mutations present in virtually all tumour cells at presentation and relapse, the function of which is not yet known. Our study establishes whole-genome sequencing as an unbiased method for discovering cancer-initiating mutations in previously unidentified genes that may respond to targeted therapies.     

Brain metabolism dictates the polarity of astrocyte control over arterioles

Calcium signalling in astrocytes couples changes in neural activity to alterations in cerebral blood flow by eliciting vasoconstriction or vasodilation of arterioles. However, the mechanism for how these opposite astrocyte influences provide appropriate changes in vessel tone within an environment that has dynamic metabolic requirements remains unclear. Here we show that the ability of astrocytes to induce vasodilations over vasoconstrictions relies on the metabolic state of the rat brain tissue. When oxygen availability is lowered and astrocyte calcium concentration is elevated, astrocyte glycolysis and lactate release are maximized. External lactate attenuates transporter-mediated uptake from the extracellular space of prostaglandin E(2), leading to accumulation and subsequent vasodilation. In conditions of low oxygen concentration extracellular adenosine also increases, which blocks astrocyte-mediated constriction, facilitating dilation. These data reveal the role of metabolic substrates in regulating brain blood flow and provide a mechanism for differential astrocyte control over cerebrovascular diameter during different states of brain activation.     

An obesity-associated gut microbiome with increased capacity for energy harvest

The worldwide obesity epidemic is stimulating efforts to identify host and environmental factors that affect energy balance. Comparisons of the distal gut microbiota of genetically obese mice and their lean littermates, as well as those of obese and lean human volunteers have revealed that obesity is associated with changes in the relative abundance of the two dominant bacterial divisions, the Bacteroidetes and the Firmicutes. Here we demonstrate through metagenomic and biochemical analyses that these changes affect the metabolic potential of the mouse gut microbiota. Our results indicate that the obese microbiome has an increased capacity to harvest energy from the diet. Furthermore, this trait is transmissible: colonization of germ-free mice with an 'obese microbiota' results in a significantly greater increase in total body fat than colonization with a 'lean microbiota'. These results identify the gut microbiota as an additional contributing factor to the pathophysiology of obesity.