Genetic linkage between immune response to GAT and the fate of RSV-induced tumors in chickens

Recent studies suggest that the gene locus controlling the fate of tumors induced by Rous sarcoma virus (RSV) is linked to theB histocompatibility complex. Birds carrying the dominant allele regress the tumor; homozygous recessives being unable to do so, develop large tumors and die. These are called progressors.The Bryan strain of RSV was inoculated into 220 6 week old Leghorns homozygous forB ¹ B ¹,B ² B ², orB ¹⁹ B ¹⁹ of which the percentages of progressors were 79, 22 and 56, respectively. The balance of each were regressors and survived.TheB ¹ B ¹ test birds were derived from special matings, i.e., high and low immune responders to the amino acid polymer, GAT. Of 67 tests progeny of theB ¹ B ¹ GAT-low mating, 63 or 94% proved to be progressors, and 6% were regressors. Of 84 test progeny of theB ¹ B ¹ GAT-high matings, 67% were progressors, and 33% were regressors. The difference between the high and low GAT responders is highly significant and indicates that the locus controlling the fate of RSV-induced tumors is closely linked to the locus controlling immune response to GAT. The latter maps within theIr region of theB histocompatibility complex.     

Reproductive traits of the freshwater oyster Etheria elliptica (Bivalvia: Etheriidae) in the Pendjari River,Benin: implications for conservation

The African freshwater oyster Etheria elliptica, which is of great economic importance throughout the continent, is facing overharvesting in many fisheries in West Africa. Its reproductive traits (sex ratio, size at sexual maturity, oocyte diameter and fecundity) were studied at four stations located along the Pendjari River, northern Benin, in April 2013. Histological techniques were implemented to identify sex and gonad development stages. Oocyte sizes were measured based on the histological images and mean oocyte diameter was 38 µm. Fecundity, estimated by counting the developing eggs, averaged 106 724 eggs and increased significantly with shell size. The average sex ratio was approximately 1:1. Hermaphrodites were rare. Males reached sexual maturity at 57.6 mm dorsoventral height, earlier than females at 64.7 mm. The majority of the oyster specimens were in ripe-spawning stages, indicating that reproductive activities partly took place towards the end of the dry season. Both mature and immature individuals were subjected to harvesting at all the investigated fishing sites. The mean size of exploited oysters was 60.6 mm, lower than the size of females at maturity. Management strategies must enforce the minimum size of 65 mm required for harvesting, particularly in open access sites where juveniles are mostly harvested.     

Topochemical aspects of nucleic-acid and protein metabolism within the neuron-neuroglia unit of the hypothalamic supraoptic nucleus

The RNA and both the total and basic protein content of individual cells were determined by cytospectrophotometry in neurons and perineuronal oligodendroglia of the hypothalamic supraoptic nucleus in rats subjected to various stresses, as well as in ground squirrels during natural hibernation. Barbiturate narcosis and deep cooling, which induced a decrease in body temperature in rats and hibernation in squirrels, caused a marked decrease of all macromolecular constituents in neurons. A similar decrease was found in the perineuronal oligodendroglia in rats, but an increase was observed in ground squirrels. After cessation of cooling, while the body temperature of the animals returned to normal, the neurons, but not the oligodendroglia, of rats showed a significant accumulation of RNA, while RNA accumulated in both neurons and perineuronal oligodendroglia in ground squirrels. Milder cooling of rats, which did not lower their body temperature, induced reciprocal changes in basic-protein content in neuronal and glial cell nuclei, with the accumulation of protein occurring initially in neurons, and subsequently in glia. When cold adaptation was accomplished, the basic protein content of neurons and glial cells returned to the control level. Four days after adrenalectomy in rats, the RNA content decreased in oligodendroglia but not in neurons of the supraoptic nucleus. This effect was completely abolished by daily injections of cortisol in the adrenalectomized animals. The data obtained indicate the existence of differences in metabolic responses to stress between neurons and glial cells of the supraoptic nucleus of the hypothalamus.     

Effect of mercury on the fish (Alburnus alburnus) chemoreceptor taste buds. A scanning electron microscopic study

Taste buds (TBs) were investigated by scanning electron microscope on various parts of the oral cavity of the bleak. (Alburnus alburnus) after differently long exposures to mercury (300 micrograms/l Hg++). This low concentration of mercury did not result in lethal effect on the bleak even after 19 days long exposure, but produced morphological changes on the TBs, which showed duration dependency. The first sign of the morphological alteration on the TBs was observed after three days long exposure, when the microridge system of the epithelial cells became damaged and the mucus secretion increased on the apical surface of the TBs. On the TBs exposed for 10 days swollen microvilliar tips of the sensory cells could be observed besides the damage of the epithelial microridge system. On the TBs exposed for 19 days degenerative changes were detected on the microvilliar system of both the supporting and receptor cells. By this time completely degenerated TBs were frequently observed.     

1-Tuple DNA sequencing: computer analysis

A new method of DNA reading was proposed at the end of 1988 by Lysov et al. According to the authors' claims it has certain advantages as compared to the Maxam-Gilbert and Sanger methods, which are revealed by automation and rapidity of DNA sequencing. Nevertheless its employment is hampered by a number of biological and mathematical problems. The present study proposes an algorithm that allows to overcome the computational difficulties occurring in the course of the method during reconstruction of the DNA sequence by its l-tuple composition. It is shown also that the biochemical problems connected with the loss of information about the l-tuple DNA composition during hybridization are not crucial and can be overcome by finding the maximal flow of minimal cost in the special graph.     

Linguistics of Nucleotide Sequences II: Stationary Words in Genetic Texts and the Zonal Structure of DNA

Abstract

Words are irregularly distributed in genetic texts. The analysis of this irregularity leads to the notion of stationary and non-stationary words. The polyW and polyS tracts are shown to be the most non-stationary words in genetic texts (here W-(AT), S-{G,C}, a polyW tract is a sequence of AT nucleotides and a polyS tract is a sequence of G,C nucleotides. The distribution of stationary words suggests a method for partitioning DNA into zones. The zones obtained in the case of the phage are interpreted in the light of the Dowe hypothesis of the modular structure of bacteriophage genomes.