The Alu I-induced bands in metaphase chromosomes of orangutan (Pongo pygmaeus)

Summary Restriction endonucleases have been recently proved to be active on fixed chromosomes, thus they are useful in chromatin structure studies. Within this class of enzymes, Alu I is able to detect the presence and localization of highly repetitive DNA sequences in human and in other mammalian and dipteran species. In this paper the pattern obtained on fixed metaphase chromosomes of orangutan (Pongo pygmaeus) by Alu I digestion and Giemsa staining is shown. The results are discussed in the light of the distribution, in this species, of the I–IV human satellite DNAs. It is also suggested that in Pongo some highly repetitive sequences, different from the major human satellites, are present.     

THE EFFECT OF HYPOCHOLESTEREMIC AGENTS ON MYELINOGENESIS

Abstract— Three drugs known to inhibit biosynthesis of cholesterol, Clofibrate, 20, 25-diazacholesterol and AY-9944 were administered by stomach intubation to suckling rats. At weaning the rats were killed and subcellular fractions, including myelin, were prepared from the brains and spinal cords and analysed for sterol content. Central nervous tissue fractions from Clofibrate-treated rats showed some decrease in total sterols, but the sterol species were qualitatively normal. AY-9944 given to rats caused high amounts of 7-dehydro-cholesterol to accumulate in all brain and spinal cord fractions with the highest amounts (32–38 percent of total sterols) in myelin. In diazasterol-treated rats desmosterol reached 48 per cent of the sterols of myelin. A group of rats was allowed to survive after the final drug intake (21 days) and their brain and spinal cord sterol content followed up to 60 days. At 30 days the proportion of dehydrocholesterol or desmosterol comprised over half the total myelin sterol. By 60 days of age the 7-dehydrocholesterol had almost completely disappeared from all fractions while substantial amounts of desmosterol were retained in myelin. Myelination was retarded by treatment with AY-9944 and 20, 25-diazasterol, possibly by the limited amount of sterols available. The metabolism of the abnormal myelin constituents in drug-treated animals is discussed in relation to the molecular structure of the myelin membrane.     

Morphogenesis of Newcastle Disease Virus in Chorioallantoic Membrane

Chick embryo chorioallantoic membrane, infected with the Blacksburg strain of Newcastle disease virus, was examined with an electron microscope to investigate the sequence of viral-induced host cell alterations. These were evident mostly in the endodermal epithelial cells lining the allantoic sac and were divided arbitrarily into three stages. Stage 1 was characterized by commencement of cell hypertrophy and hyperplasia and presence of fewer cytoplasmic inclusion bodies normally found in the cells; in stage 2, juxtanuclear nucleocapsid-glycogen aggregates appeared, and there were increased numbers of microvilli; stage 3 was characterized by increased cytoplasmic density and evidence of viral assembly and release. The morphological features of viral assembly and the virion are also described.     

LIPID COMPOSITION OF THE CENTRAL NERVOUS SYSTEM OF MARINE VERTEBRATES

—The lipid composition of the central nervous system of some marine vertebrates and two mammalian species (rat and man) was analysed by one- and two-dimensional quantitative thin-layer chromatography, and the cerebroside fatty acids were analysed by gas chromatography. The concentrations of sphingomyelin and cerebrosides are higher in mammals than in fishes, while no significant differences are observed for other lipid classes. Furthermore, in mammals the ratio between hydroxy and normal fatty acids in the cerebrosides is much higher than in fishes. The cerebrosides of mammals contain more very long chain fatty acids than those of marine vertebrates.     

Substructure of membranes in cultivated chick embryo fibroblasts

Summary Electron microscope examination of the plasma membrane of chick embryo fibroblasts cultured in vitro revealed the presence of a single osmiophilic layer about 90 Å thick and a substructure composed of ovoid sub-units associated with an amorphous component. These ovoid sub-units measured approximately 112 Å along the major axis and 75 Å along the minor axis and were composed of a central core, approximately 30 Å by 60 Å, surrounded by a peripheral component.Examination of other membranous components of these cells revealed a similar ovoid subunit structure in a single layered membrane. Differences in thickness and in the sizes of ovoid sub-units were seen in these membranes. The ergastoplasmic membranes, the outer nuclear membranes, the outer mitochondrial and the Golgi membranes were found to be the thinnest.These varied in thickness from approximately 75 Å to 80 Å. The thickest membranes seen were the inner nuclear membranes. These were approximately 100 Å thick. The dimensions of the ovoid sub-units corresponded with differences in the thickness of the various membranes. These findings support the concept of a particulate substructure of cell membranes.This work was aided by Research Grant PH 5593 from the National Science Foundation. Some of the equipment used was purchased with funds from the National Institutes of Health Grant 2TI GM 326. I wish to thank Dr. Robert M. Dougherty from the Department of Microbiology who grew and supplied me with the chick embryo fibroblast cultures used in these studies, and Mrs. Ursula Feller fer her technical assistance.     

Purine metabolism: determination of adenyl deaminase in human lymphocytes

Adenylic acid (AMP) deaminase is a "catabolic enzyme" involved in nucleotide degradation, transforming AMP into inosinic acid (IMP). We present a simple method for the determination of the enzyme activity, which combines high sensitivity with requirement of low quantities of lymphocytes. Human lymphocytes were isolated with a Lymphocyte Separation Medium from FLOW and sonicated. After centrifugation at 2,000 rpm x 10 min and treatment with Norit A, the cells were incubated at 37 degrees C with ATP 0.8 mM and 14C-AMP 0.1 mM (specific activity 12 microCi/mumole) in potassium phosphate 100 mM (pH 7.4). 14C-IMP and 14C-AMP were separated through HPLC by an isocratic elution, with 20 mM KH2PO4 (pH 5.5) at a 1.5 ml/min flow rate. Identification of the nucleotides was carried out through retention time, coelution with internal standards: their evaluation by determining the radioactivity of the collected peaks. The enzyme activity is decreased in patients affected by CLL: the decrease is evident only when data are referred to the single cells and not when they are referred to the protein.     

Unusually high rates of metabolism of DHT in cytosols of the quail uropygial gland

The metabolism of DHT in the cytosol of the quail uropygial gland was found to be so high that the steroid was almost completely inactivated within 2 hours of incubation at 0 C. In these conditions, DHT cannot be used for the characterization of androgen receptors. By contrast, R 1881 and mibolerone, which are not metabolized, can be used as alternative ligands. Moreover, the extremely high metabolism of DHT questions the physiologic role of this steroid in the quail uropygial gland.     

Genetic structure of the population of Sicily.

Genetic heterogeneity within Sicily was investigated on the basis of ACP1, ADA, ESD, GLO1, PGD, PGM1, PGM2, SODA, ABO, and MN gene frequencies, and compared to those of other regions of Italy for which these same loci have been examined. Correspondence analysis revealed no differences within the island, at least at the provincial level, but showed genetic differentiation among Italian regions, distinctly clustering northern, central, and southern populations, respectively. These data indicate a close relationship between Sicily and southern Italy. In addition, the contribution of Middle Eastern populations to the gene pool of Sicily was evident.     

Form changes in the sea bass, Dicentrarchus labrax (Moronidae: Teleostei), after acclimation to freshwater: an analysis using shape coordinates

Synopsis Morphological changes in the sea bass, Dicentrarchus labrax (Perciformes: Moronidae), were investigated after an experimental acclimation trial to freshwater. The sea bass is an euryhaline species occurring in the Mediterranean and west Atlantic from 30° N to 55° N. Part of the offspring of a pool of breeders was acclimated to freshwater at 9 months of age while maintaining the original stock in marine water. The effect of acclimation to freshwater over the entire form of the fish was studied through geometric morphometrics (shape coordinates). Changes in the form were shown graphically as landmark displacements though age classes 7,12, 15, 19 and 24 months and were discussed in the light of integrated growth. A significantly faster growth in freshwater was detected. Shape coordinates analyzed through multivariate statistics show that significant differences in shape arise after acclimation to freshwater. Moreover, the uniform component of shape change reveals a major effect of stretching or compression perpendicular to the body axis which is common and conservative in both trials. Differences are discussed in terms of selection and ecophenotypism.