Inositol- and Galactose-Binding Lectins of Chicken Brain Fractions Enriched with Glial Cells

Galactose- and inositol-binding proteins with lectin activity (GL-GAL and GL-I, respectively) were isolated from membranes enriched with cells of chicken brain fractions. Both lectins are glycoproteins of molecular mass 13.5 and 11.5 kDa, respectively; they show a high affinity to EDTA (GL-I) and EGTA (GL-GAL, GL-I), which indicates an important role of Ca⁺² in molecular organization of these lectins. In brain glial cells of chick embryos, unlike adult chickens, a soluble form of lectins has been revealed; it is easily extracted with 2 mM EDTA and shows sensitivity to L-lactose, D-galactose, and N-acetyl-D-galactosamine. It is suggested that in the course of embryonal and postembryonal development of the chicken brain, a transformation and qualitative changes of the lectin spectrum occur due to a change of function of glial cells.     

Carotenoid synthesis in Streptomyces setonii ISP5395 is induced by the gene crtS, whose product is similar to a sigma factor

In many species of actinomycetes, carotenogenesis can be photoinduced. The capacity to respond to photoinduction is, however unstable and, in various strains of Streptomyces, is lost at a relatively high frequency. In Streptomyces setonii ISP5395, which normally produces no carotenoids, carotenoid-producing mutants can be obtained following protoplast regeneration. We report here the characterization of a gene, crtS, which was isolated from one such mutant and can confer on wild-type S. setonii ISP5395 cells the capacity to synthesize carotenoids. Sequence analysis of crtS reveals an open reading frame, which shows homology to genes that encode alternative sigma factors in Bacillus subtilis. We propose that crtS encodes a sigma factor which is necessary for the expression of a cryptic gene(s) for carotenoid biosynthesis in S. setonii ISP5395.     

Thickness of renal glomerular capillary basement membrane in the offspring of diabetic rats fed a regular or high-sucrose diet

Numerous animal model studies of diabetes mellitus have been reported. Diabetes-induced vascular damage is a common cause of systemic organ damage in humans and animals. Many investigations have been made of human and animal offspring of diabetic mothers. The present report documents the sequential glomerular basement membrane (GBM) thickness in fetuses and infants of diabetic rats. The postnatal increase in GBM thickness was similar in the offspring of control and diabetic rats, and was not related to the sucrose concentration in the diet.     

Determination of oxalyl thiolesters, N-oxalylcysteine and N-oxalylcysteamine in biological materials

A convenient method is described for the quantitative analysis of oxalyl thiolesters (OTEs), a newly discovered class of mammalian metabolites, in biological samples. By this particular technique the total concentration of all OTEs in the sample is determined. The method involves first reacting the biological material with cysteamine (2-aminoethanethiol) or cysteine under conditions that convert OTEs quantitatively to N-oxalylcysteamine (or N-oxalylcysteine), followed by reaction with monobromobimane to give a highly fluorescent derivative that is analyzed by reversed-phase ion-pair chromatography, with tetrabutylammonium ion as the counterion and N-(2-mercaptopropionyl)glycine as an internal standard. The method is capable of detecting as little as 0.6 pmol of the bimane derivative of the N-oxalyl compound in a single HPLC injection. The application of this method has led to the discovery that not only OTEs but also N-oxalylcysteine and N-oxalylcysteamine are normal mammalian metabolites. In various rat tissues the OTE concentration ranges up to 65 nmol/g (wet wt), the N-oxalylcysteine concentration is approximately 10 nmol/g, and the N-oxalylcysteamine concentration is 0-3 nmol/g.     

Assay of 1L-myo-inositol-1-phosphatase using a fluorometric method.

1L-myo-Inositol-1-phosphatase, an enzyme purified from brain tissues, catalyzes the dephosphorylation of 1L-myo-inositol 1-phosphate. This enzyme has become the subject of intense research interest, since myo-inositol is needed for the resynthesis of phosphatidylinositol. We have developed a sensitive fluorometric assay for detecting the activity of 1L-myo-inositol-1-phosphatase. The assay is based on o-aminobenzoyl beta-glycerophosphate fluorescence, according to the following principles: (I) The fluorescence yield of o-aminobenzoyl beta-glycerophosphate is increased by 2.75-fold in the presence of saturating concentrations of bovine serum albumin. (II) o-Aminobenzoyl beta-glycerophosphate has the same fluorescence yield as o-aminobenzoyl glycerol, but the latter does not bind to bovine serum albumin. (III) Dephosphorylation of the substrate, catalyzed by the monophosphatase, makes less o-aminobenzoyl beta-glycerophosphate available for binding to bovine serum albumin, thereby producing a decrease in the fluorescence intensity.     

The participation of the striatum in the central regulation of gonadal hormonal function]

Intrastriatal corticotrophin-releasing hormone (CRH) was shown to induce a decrease in the plasma tectosterone concentration. Besides, the 6-OHDA pre-treatment completely prevented the suppression of plasma testosterone in response to intrastriatal CRH administration. The findings suggest that the striatum is involved in the extrahypothalamic regulation of the gonadal endocrine function.     

Growth and shaping of the fin and limb buds

The development of the fin and limb buds involves a balance of centrifugal (active) and centripetal (passive) mechanical forces, the first of which acts to move the walls of these structures away from each other and the second of which holds them together. When the volume of the mesodermal core increases, the generated force meets with the resistance of the basal membrane, and as a result, the limb bud has a tendency to acquire a cylindrical shape. Collagen fibers, individual mesenchymal cells, and their groups hold together the dorsal and the ventral wall of the limb bud, prevent the movement of these walls away from each other, and in this way direct bud growth along the proximodistal and the anteroposterior axes. The balance of the forces which stretch the ectodermal layer and those which constrain it has also been observed in the development of other body parts.     

Vegetation fluctuation in mediterranean dune ponds in relation to rainfall variation and water extraction

Abstract. The structure of dune ponds hygrophytic vegetation has a spatial organisation in belts around the pond basin, closely related to water level and flooding regime. Doñana National Park has an important representation of temporal dune ponds, which are subjected to rainfall fluctuations and may be suffering the impact of water extraction from the neighbouring tourist resort. Permanent transects in a vegetation complex of five dune ponds have been monitored during a eight year period (1990-1997). This period was characterised by a number of dry years (annual rainfall around 300 mm), located between two wet cycles (800-900 mm). Transects were analysed in 1990 (wet period), 1994 (dry) and 1997 (wet) by hierarchical agglomera-tive clustering. During the dry period hygrophytic species showed regression, with a high mortality of some species like Ulex minor, while the xerophytic species advanced to lower areas. Seedlings of some xerophytic species colonised the dry surface of the pond basin. The lowering of the water table varied in the different ponds, ranging from 312 to 190 cm depending on topography and the distance to the pumping area. The new period of flooding during 1995-96 and 1996-97 cycles provided the opportunity for hygrophytic spe cies to re-establish themselves in their original places. This study suggest that changes in vegetation are caused by the interaction between weather conditions and human disturbance (water extractions). In our example man-made disturbance is more marked during the dry periods while wet periods tend to obscure the effects of water extractions. From a management perspective, long-term monitoring of water table and vegetation structure is revealed as a key procedure to the management of land-water ecotones on pressured areas and threatened habitats.     

Morphological variation in intergrade pupfish populations from the Pecos River, Texas, U.S.A.

In the early 1980s, sheepshead minnow Cyprinodon variegates was introduced into the Pecos River, Texas, U.S.A. where it hybridized with the endemic Pecos pupfish C. pecosensis . By 1985, pupfish populations throughout approximately 300 km of the river consisted exclusively of individuals of hybrid origin (intergrades). There was significant ( P <0·05) geographic variation in most morphological characters; the general pattern of variation was of a bidirectional cline centred near Pecos, Texas. At that site, morphology of intergrade populations resembled mostly that of the introduced species. Upstream and downstream from Pecos, morphology shifted progressively toward that typical of the native form. Intergrade populations were morphologically intermediate to the parental forms, showed a rapid approach to random assortment of characters, and generally exhibited greater morphological variability than occurred in either parent species. These observations and the consistent lack of bimodality in frequency distributions of a morphological hybrid index support the contention that intergrade populations comprise panmictic admixtures of C. variegates and C. pecosensis .