Dietary effects on the formation of dolichyl monophosphate mannose by microsomal preparations of rat adipose tissue

Microsomal preparations from rat adipose tissue catalyse the transfer of [¹⁴C]mannose from GDP-[¹⁴C]mannose to an endogenous acceptor forming a [¹⁴C]mannosyl lipid. The mannosyl lipid co-chromatographs with hen oviduct dolichyl monophosphate β-mannose on three solvent systems. It is stable to mild alkaline hydrolysis, but strong alkaline treatment yields a compound that co-migrates with mannose 1-phosphate. The mannosyl lipid is labile to mild acid hydrolysis, yielding [¹⁴C]mannose. Formation of the compound is reversible by GDP, but not GMP, and is stimulated by exogenous dolichyl phosphate.

The kinetics of transfer of [¹⁴C]mannose from GDP-[¹⁴C]mannose to form dolichyl monophosphate mannose were studied by using preparations derived from rats fed on one of four diets: G (high glucose), L (high lard), F (fructose) or GC (high glucose, 0.9% cholesterol). The K_m and V_max. values for transfer from GDP-mannose were virtually indistinguishable in the four preparations.

In the absence of exogenous dolichyl phosphate, the largest amount of transfer of [¹⁴C]mannose into the mannosyl lipid was observed with preparations from fructose-fed animals. Preparations from glucose-fed animals showed about 60% as much transfer, whereas membranes from rats fed the other diets showed intermediate values between the fructose- and glucose-fed animals. The inclusion of cholesterol in the glucose diet elicited an increase in transfer of mannose.

Under conditions of saturating exogenous dolichyl phosphate, preparations from lard-fed animals have 1.5 times as much enzyme activity as do preparations from animals fed the other three diets.

     

Tissue specific nuclear antigens in the germinal vesicle ofXenopus laevis oocytes

Summary A library of hybridoma cell lines has been established which produce monoclonal antibodies against antigens from the germinal vesicle ofXenopus laevis oocytes. Many of the antigens are also found in the nuclei ofXenopus embryonic cells in culture. The fate of two of these antigens during embryogenesis was traced by immunofluorescence on embryo and tadpole sections. Early in development these antigens appear to be evenly distributed in the nuclei of all cells. In later stages they gradually disappear from most embryonic structures but are strongly accumulated in the nuclei of some specific cell types and organs.     

Social development of stumptail macaques (Macaca arctoides): Synchrony of changes in mother-infant interactions and individual behaviors during the first 60 days of life

Several categories of social and individual behaviors were recorded during the first 60 days of life for seven stumptail macaques. Mother-infant interactions tended to decelerate in synchrony with increases in infant nonsocial behaviors, such as object manipulation. Several aspects of stumptail social growth during the first two months were similar to those of rhesus and other macaques. Approaching-leaving, which has been used previously as an index of waning of the mother-infant bond, was due more to infants than to mothers during the second month of life     

Rhesus monkey micro mixed lymphocyte and mitogen reactivity: Optimal conditions and normal variability

Optimal conditions for the rhesus monkey micro mixed lymphocyte system with multiple automated harvesting of samples were evaluated. Parameters studied were cell concentration, length of culture period, methods of inactivation of cell populations, supplementation of media, type of culture plates, and changes in the reactivity of cells from individual animals over an extended time period. This work was supported in part by Portland Veterans Administration Hospital, Portland, Oregon, and the General Research Support Branch of the U.S. Public Health Service Grant RR00163, the Bureau of Medicine and Surgery, Navy Department, Work Unit No. M4318. 01.007ABG2. The opinions or assertions contained herein are the private ones of the authors and are not to be construed as official or reflecting the views of the U.S. Navy Department or the Naval service at large. The animals used in this study were handled in accordance with the provisions of Public Law 89–54 as amended by Public Law 91–579, “Animal Welfare Act of 1970,” and the principles outlined in the “Guide for the Care of Laboratory Animals,” U.S. Department of Health, Education, and Welfare Publication No. (NIH) 73-23.     

Studies on the mode of action of calciferol: Biological activity of 1α,24R,25-trihydroxyvitamin D3 in the chick

The biological activity of 1α,24R,25-trihydroxyvitamin D₃ [1α,24R,25(OH)₃D₃] was elevated in comparison to the hormonally active form of vitamin D₃, 1α,25-dihydroxyvitamin D₃ [1α,25(OH)₂D₃], in the rachitic chick in terms of its ability to (a) stimulate intestinal calcium absorption, (b) mobilize bone calcium, (c) induce intestinal calcium binding protein, (d) modulate the level of enzyme activity of the renal 25-OH-D₃-1-hydroxylase system, and (e) interact with the intestinal cystosol-chromatin receptor system for the 1α,25(OH)₂D₃ receptor system. In each of these assays, the relative ratio of activity of 1α,24R,25(OH)₃D₃ to 1α,25(OH)₂D₃was (a) 25–50, (b) ca. 20, (c) 10, (d) 50, and (e) 36%, respectively.     

A new red-bracted species of Calathea (Marantaceae) from Peru

Calathea schunkei from San Martín Province, Peru, is described as new. This species is distinguished by the red bracts and unusual floral morphology. The petals do not reflex at anthesis, the outer staminode is lacking, and the stigma is blunt rather than the typical “scoop” shape. These unusual floral features are shared withC. timothei, a high altitude Colombian species.     

Anterior segment mesenchymal dysgenesis: Probable linkage to the MNS blood group on chromosome 4

Thirty-seven blood samples were analyzed for linkage from members of a single family with an anterior segment mesenchymal dysgenesis (ASMD1) with variable expressivity affecting members of at least six generations. Maximum-likelihood analysis for linkage between ASMD1 and 14 biochemical and serological markers in the family showed a probable linkage between ASMD1 and the MNS blood group on the long arm of chromosome 4 (Z = 2.36 at a recombination fraction of .09).     

Muscarinic Cholinergic Stimulation of Exogenous Phosphatidylinositol Hydrolysis Is Regulated by Guanine Nucleotides in Rabbit Brain Cortical Membranes

Rabbit brain cortical membranes, which have been extracted with 2 M KCl, hydrolyze exogenously added [3H]phosphatidylinositol [( 3H]PI) in a guanine nucleotide- and carbachol-dependent manner. Both oxotremorine-M and carbachol are full agonists with EC50 values of 8 and 73 microM, respectively. Pirenzepine and atropine inhibit carbachol-stimulated [3H]PI hydrolysis. The hydrolysis-resistant guanine nucleotide analog guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) is the most potent in supporting carbachol-stimulated hydrolysis of PI. There is no effect of carbachol in the absence of guanine nucleotides or in the presence of 100 microM adenosine 5'-O-(3-thiotriphosphate), adenosine-5'-(beta, gamma-imido)triphosphate, or sodium pyrophosphate. Guanylyl-5'-(beta,gamma-imido)triphosphate [Gpp(NH)p] in the presence of carbachol also stimulates PI hydrolysis although much less than that seen with GTP gamma S. GDP and Gpp(NH)p are potent antagonists of the GTP gamma S-dependent carbachol response. Optimal stimulation by carbachol and GTP gamma S was observed at 0.3-1 microM free Ca2+ and 6 mM MgCl2. Limited trypsinization resulted in loss of receptor-regulated PI breakdown and a slight decrease in basal activity. These results demonstrate that phospholipase C hydrolysis of exogenous PI by rabbit cortical membranes may be stimulated by carbachol in a guanine nucleotide-dependent manner.     

Seasonal fluctuations of zooplankton biomass in Lake Xolotlán (Managua)

Seasonal fluctuations of zooplankton biomass (dry weight) were determined during a year in two localities of Lake Xolotlán (Managua). Biomass estimations of the most common species of rotifers, cladocerans and copepods were made. The maximal zooplankton biomass was observed in February–April (dry season) in coincidence with the period of highest phytoplankton abundance. Copepods contributed with 78% and 84% to the mean zooplankton biomass at points 1 and 7, respectively. Cladocera biomass was lowest during most of the year, and it was probably controlled by fish predation. Development of rotifer biomass was more intense during the rainy season, when detritus particles were more abundant. Daily fluctuations of zooplankton biomass were not pronounced.     

Biotransformation of cycloalkanones: Controlled oxidative and reductive bioconversions by anAcinetobacter species

Summary Culture conditions have been optimised to enable resting cell cultures ofAcinetobacter calcoaceticus NCIMB 9871 to selectively undertake either oxidative or reductive biotransformations of various bicyclic ketones.