Genetic mapping of meander tail, a mouse mutation affecting cerebellar development

The meander tail mouse harbors a recessive mutation on chromosome 4 that affects the anterior lobes of the cerebellum and the caudal vertebrae. Examination of the mea/mea cerebellum reveals that the complete disorganization of all cell types seen in the anterior lobes is separated by a sharp and consistent boundary from the normal cytoarchitecture of the posterior lobes. In the absence of any biochemical information regarding the affected gene product, attempts to clone the gene must rely on the strategy of reverse genetics. As an initial step in this process we have constructed a genetic linkage map spanning 68 cM of chromosome 4 using an intersubspecific phenotypic backcross. The loci included in this analysis are Calb, Ggtb, Lv, b, Ifa, mea, D4Rp1, Glut-1, Lck, Lmyc-1, and Eno-1. This analysis positions the mea phenotypic locus in the interval between Ifa and Glut1. These results also further define regions of homology between mouse chromosome 4 and human chromosomes 8, 1, and 9. This linkage map provides the means to evaluate candidate genes, and to identify tightly linked markers useful for cloning the meander tail locus.     

Effect of malnutrition on susceptibility of mice to Trypanosoma musculi: vitamin A-deficiency.

Vitamin A-deficiency was studied in mice infected with Trypanosoma musculi. Irrespective of diet, trypomastigotes (trypanosomes) appeared in peripheral tail blood of all inoculated mice after 6-day incubation periods. On the average, vitamin A-deficient mice had parasitemias about 10 times greater than animals fed a complete diet and 8 times pair-fed controls. Parasitemias lasted longer in vitamin-deficient hosts, and reached a maximum five days later than those from control hosts.     

Comparison of Effects of Long-term Corticotrophin and Corticosteroid Treatment on Responses of Plasma Growth Hormone,ACTH, and Corticosteroid to Hypoglycaemia

The development of the highly sensitive cytochemical bioassay for ACTH has permitted the measurement of plasma ACTH levels during the insulin hypoglycaemia test (I.H.T.) in patients treated with corticosteroids and corticotrophin. The ACTH, corticosteroid, and growth hormone (GH) responses in the I.H.T. were measured in three groups of 12 rheumatoid arthritis patients. One group was receiving long-term corticotrophin treatment, the second was undergoing long-term corticosteroid treatment, and the third had never received systemic hormone therapy. The increments in plasma ACTH, corticosteroids, and GH were diminished in the corticosteroid-treated group, as were increments in plasma GH and ACTH in the corticotrophin-treated group; but in this group the corticosteroid increment was normal. Examination of the area under the curve of the ACTH response showed that the total amount of ACTH secreted was normal though the rate of secretion was reduced. In the corticosteroid-treated group both rate and total secretion were diminished.     

The influence of hormones and inflammatory agents on C-reactive protein, cortisol and alanine aminotransferase in the plaice (Pleuronectes platessa L.)

Endotoxin stimulates production of both C-reactive protein (CRP) and cortisol in the plaice within 24 hr. Cortisol alone (optimum dose i.p. 500 micrograms/300 g wt fish) also stimulates CRP production and the possibility that endotoxin acts through cortisol was examined. Dexamethasone suppresses cortisol production but elevates CRP. Cortisol levels are restored to normal within 24 hr of endotoxin injection. Turpentine and ACTH which stimulate cortisol do not affect CRP. Endotoxin and cortisol have no significant effect on alanine aminotransferase activity in the serum and liver although it is elevated in the serum within 24 hr of the administration of adrenalin or turpentine.     

The effect of temperature and relative humidity on the survival of bacteria attached to dry solid surfaces

The effect of relative humidity (r.h.) (0%, 34% and 75%) and temperature (4, 15 and 25°C) on the desiccation survival of Pseudomonas sp., Acinetobacter calcoaceticus , a coryneform, Staphylococcus sp., and Staphylococcus aureus attached to and grown on glass surfaces was studied. The survival of Gram-negative and Gram-positive species was similar. Bacterial survival was shortest at 25°C for all species studied, and in most cases longest at 4°C. The effect of r.h. on survival varied with species. The number of microcolonies and the number of cells within microcolonies for Pseudomonas sp. increased on the dry surfaces after 7 d incubation under all desiccation conditions.     

Free and polymerized tubulin in cultured bone cells and Chinese hamster ovary cells: the influence of cold and hormones

A low pH method of liposome-membrane fusion (Schneider et al., 1980, Proc. Natl. Acad. Sci. U. S. A. 77:442) was used to enrich the mitochondrial inner membrane lipid bilayer 30-700% with exogenous phospholipid and cholesterol. By varying the phospholipid-to- cholesterol ratio of the liposomes it was possible to incorporate specific amounts of cholesterol (up to 44 mol %) into the inner membrane bilayer in a controlled fashion. The membrane surface area increased proportionally to the increase in total membrane bilayer lipid. Inner membrane enriched with phospholipid only, or with phospholipid plus cholesterol up to 20 mol %, showed randomly distributed intramembrane particles (integral proteins) in the membrane plane, and the average distance between intramembrane particles increased proportionally to the amount of newly incorporated lipid. Membranes containing between 20 and 27 mol % cholesterol exhibited small clusters of intramembrane particles while cholesterol contents above 27 mol % resulted in larger aggregations of intramembrane particles. In phospholipid-enriched membranes with randomly dispersed intramembrane particles, electron transfer activities from NADH- and succinate-dehydrogenase to cytochrome c decreased proportionally to the increase in distance between the particles. In contrast, these electron- transfer activities increased with decreasing distances between intramembrane particles brought about by cholesterol incorporation. These results indicate that (a) catalytically interacting redox components in the mitochondrial inner membrane such as the dehydrogenase complexes, ubiquinone, and heme proteins are independent, laterally diffusible components; (b) the average distance between these redox components is effected by the available surface area of the membrane lipid bilayer; and (c) the distance over which redox components diffuse before collision and electron transfer mediates the rate of such transfer.     

Effect of thyroid hormones on acid cholesterol ester hydrolase activity in rat liver,heart and epididymal fat pads

The regulation of acid cholesterol ester hydrolase activity by thyroid hormones was studied in subcellular fractions from rat liver, heart, and epididymal fat pads; hydrolase activity was determined at pH 5 with a glycerol-dispersed cholesterol oleate substrate preparation. Acid cholesterol ester hydrolase activity was decreased in liver preparations from thyroidectomized rats relative to activity in livers from euthyroid control rats. Administration of triidothyronine to either euthyroid or hypothyroid (thyroidectomized) rats resulted in an increase in acid cholesterol ester hydrolase activity in liver preparations. Similar effects of thyroidectomy and the administration of triiodothyronine on acid cholesterol ester hydrolase activity were observed with fat pad preparations. In contrast, no effect of thyroid hormones was observed on acid cholesterol ester hydrolase activity in heart. These results suggest that thyroid hormones may regulate the catabolism of serum lipoproteins, in part, by alterations in lysosomal acid cholesterol ester hydrolase activity in liver and epididymal fat pads.