Failure of low level γ-irradiation of infective larvae to influence establishment or expulsion of Trichostrongylus colubriformis in guinea pigs

Trichostrongylus colubriformis infective larvae were subjected to various levels of γ-irradiation and administered to guinea pigs. The worms surviving were subsequently counted. Irradiation with 12.9 C kg⁻ inhibited worm establishment but lower doses neither influenced worm establishment nor survival.     

The interstitial tissue of the testis of the River lamprey, Lampetra fluviatilis

The cytology of the interstitial cells of the testis of the river lamprey has been studied from the autumn when the upstream migration begins up to the completion of sexual maturation in the following spring. In the early stages of spermatogenesis the interstitial tissue consists of isolated interlobular connective tissue cells. During the winter these appear to increase in numbers and form compact groups sometimes showing an acinar type of structure. In the earlier stages of the secretory cycle the cytoplasm contains small osmiophilic and sudanophilic granules, which appear to aggregate to form much larger lipid positive masses. In the later stages of spermatogenesis in early spring, the interstitium accumulates large areas of lipid and cholesterol positive droplets and in fixed material the cytoplasm shows extensive vacuolization. In the terminal stages the cells undergo complete disintegration. It seems probable that the stage when the interstitium shows masses of lipid and cholesterol positive droplets represents a phase of degeneration and that the secretion of hormone occurs in earlier stages. No convincing evidence has been obtained for the presence of the enzyme steroid-3β-ol-dehydrogenase during the later stages of the secretory cycle. There is evidence that following the degeneration of the interstitium there may be a replacement of the secretory tissue by the transformation of residual connective tissue elements, which may then re-enter the secretory phase. The changes in the interstitium are paralleled by hypertrophy and evidence of lipid metabolism in the modified fibroblasts of the lobular wall and this tissue may also be involved in the secretory activity of the testis.     

HAT: Hypergeometric Analysis of Tiling-arrays with application to promoter-GeneChip data

Background  

Tiling-arrays are applicable to multiple types of biological research questions. Due to its advantages (high sensitivity, resolution, unbiased), the technology is often employed in genome-wide investigations. A major challenge in the analysis of tiling-array data is to define regions-of-interest, i.e., contiguous probes with increased signal intensity (as a result of hybridization of labeled DNA) in a region. Currently, no standard criteria are available to define these regions-of-interest as there is no single probe intensity cut-off level, different regions-of-interest can contain various numbers of probes, and can vary in genomic width. Furthermore, the chromosomal distance between neighboring probes can vary across the genome among different arrays.