Changes in tight junctions of thyroid epithelium with changes in thyroid activity

The morphology of the tight junction of rat thyroid epithelium was examined in freeze-fractured material fixed in glutaraldehyde and briefly glycerinated. In normal thyroids the overall appearance of this junctional specialization resembled that of other cell types in many respects. Short-term changes in thyroid activity and hypophysectomy for 3 wk did not obviously affect the appearance of tight junctions. Feeding of the goitrogen, thiouracil, which stimulates secretion of thyroid-stimulating hormone, resulted in the appearance of some very narrow and some very wide, tight junctions or sometimes junctions with both wide and narrow regions within the same cell.     

The Probabilities of Unique Events

Many theorists argue that the probabilities of unique events, even real possibilities such as President Obama''s re-election, are meaningless. As a consequence, psychologists have seldom investigated them. We propose a new theory (implemented in a computer program) in which such estimates depend on an intuitive non-numerical system capable only of simple procedures, and a deliberative system that maps intuitions into numbers. The theory predicts that estimates of the probabilities of conjunctions should often tend to split the difference between the probabilities of the two conjuncts. We report two experiments showing that individuals commit such violations of the probability calculus, and corroborating other predictions of the theory, e.g., individuals err in the same way even when they make non-numerical verbal estimates, such as that an event is highly improbable.     

The character and use of the Soros Hill Obsidian source,Antiparos (Greece)

This article details the geological and elemental character of the obsidian from the Soros Hill source on the Cycladic island of Antiparos, Greece. EDXRF was used to analyse 40 geological geo-referenced samples. The products are clearly chemically discriminated from those of the other Aegean sources, and those from the Carpathians and central Anatolia. While the obsidian is of excellent tool-making quality, the small size of its nodules seems to have made it a less attractive raw material, attested at only a handful of prehistoric sites in the central Cyclades.     

Taphonomy of dense concentrations of juvenile ammonoids in the Upper Cretaceous Mancos Shale,east-central Utah,USA

Dense concentrations of juvenile ammonoids were recently discovered in the Upper Cretaceous Mancos Shale of east-central Utah. In this paper, we describe this remarkable fossil occurrence and propose a taphonomic model to explain it. Large accumulations of cephalopods are not uncommon in the stratigraphic record, though concentrations of juveniles are relatively rare. Lithologic, geochemical, and stratigraphic evidence suggest that the unusual fossil occurrence we document here resulted from a combination of factors. We think the cause of these dense concentrations of juvenile ammonoids involves the hypothesized semelparous reproductive strategy of ammonoids, environmentally driven mass mortality, and a peculiar taphonomic phenomenon. In our model, an important role is played by the adverse oceanographic conditions common during the extreme greenhouse global climate regime of the Cretaceous, manifested by the well-known Ocean Anoxic Events around the time when these deposits were formed. The proposed mechanisms responsible for the mass accumulations we report here have operated at other times in Earth history, and may help explain similar occurrences elsewhere in the fossil record.     

LIMaS: the JAVA-based application and database for microarray experiment tracking

Microarrays allow monitoring of gene expression for tens of thousands of genes in parallel and are being used routinely to generate huge amounts of valuable data. Handling and analysis of such data are becoming major bottlenecks in the utilization of the technology. To enable the researcher to interpret the results postanalysis, we have developed a laboratory information management system for microarrays (LIMaS) with an n-tier Java front-end and relational database to record and manage large-scale expression data preanalysis. This system enables the laboratory to replace the paper trail with an efficient and fully customizable interface giving it the ability to adapt to any working practice, e.g., handling many resources used to form many products (chaining of resources). The ability to define sets of activities, resources, and workflows makes LIMaS MIAME-supportive.LIMaS is available for download at (http://www.mgu.har.mrc.ac.uk/microarray.)     

Distribution of purinergic P2X receptors in the equine digit, cervical spinal cord and dorsal root ganglia

Purinergic pathways are considered important in pain transmission, and P2X receptors are a key part of this system which has received little attention in the horse. The aim of this study was to identify and characterise the distribution of P2X receptor subtypes in the equine digit and associated vasculature and nervous tissue, including peripheral nerves, dorsal root ganglia and cervical spinal cord, using PCR, Western blot analysis and immunohistochemistry. mRNA signal for most of the tested P2X receptor subunits (P2X_{1–5, 7}) was detected in all sampled equine tissues, whereas P2X₆ receptor subunit was predominantly expressed in the dorsal root ganglia and spinal cord. Western blot analysis validated the specificity of P2X_{1–3, 7} antibodies, and these were used in immunohistochemistry studies. P2X_{1–3, 7} receptor subunits were found in smooth muscle cells in the palmar digital artery and vein with the exception of the P2X₃ subunit that was present only in the vein. However, endothelial cells in the palmar digital artery and vein were positive only for P2X₂ and P2X₃ receptor subunits. Neurons and nerve fibres in the peripheral and central nervous system were positive for P2X_1–3 receptor subunits, whereas glial cells were positive for P2X₇ and P2X_{1 and 2} receptor subunits. This previously unreported distribution of P2X subtypes may suggest important tissue specific roles in physiological and pathological processes.