Corticotropin releasing factor stimulates growth hormone secretion in neonatal rats

Corticotropin releasing factor (CRF) both stimulates ACTH secretion from the pituitary and inhibits secretion of growth hormone (GH) in adult rats through actions in the CNS. The purpose of the present study was to evaluate these pituitary and central actions of CRF in neonatal rats, in which the hypothalamo- pituitary adrenal (HPA) axis is relatively hypo-functional. The results of this study show that central or peripheral administration of CRF evokes a marked dose-related rise in serum corticosterone in 6-day old rats. The same doses of CRF stimulate, rather than inhibit GH secretion. These results suggest that CRF has unique central actions early in ontogeny.     

Purification, properties and cation activation of galactosyltransferase from lactating-rat mammary Golgi membranes

Galactosyltransferase was purified from Golgi membranes of lactating-rat mammary gland and studied with respect to its physical and enzymic (lactose synthetase) properties. The enzyme occurred in both monomeric (43-46 kDa) and apparently dimeric (90 kDa) forms. It was very unstable except in the presence of phospholipid, detergent, or cations binding to site 2. The amino acid composition and the N-terminal sequence closely resembled that of the human and bovine milk enzymes, particularly in respect to a Pro-Pro-Pro-Pro sequence. Kinetic studies demonstrated a high-affinity Mn2+-binding site (1) essential for activity, and a low-affinity Mn2+-binding site (2) that could also bind spermidine or clupeine. Mn2+ binding at site 2 raised Vmax fivefold. Spermidine binding at site 2 enhanced Mn2+ binding at site 1, and influenced binding of glucose. At physiological glucose concentration, clupeine or spermidine activated nearly as well as 15 mM MnCl2 and are regarded as models of a natural cation activator that remains to be isolated. Evidence is given for an essential histidine residue in the galactosyltransferase. It is proposed that site 1 Mn2+ participates directly in the reaction mechanism, whereas site 2 is a regulator site allosterically activated by a basic protein.     

Paternal Imprinting of Inversion Uab(1) Causes Homeotic Transformations in Drosophila

Paternal transmission of the bithorax-complex (BX-C) rearrangement, inversion Uab(1), causes a specific dominant gain of function phenotype in most abdominal segments. This represents a case of paternal imprinting since the mutant phenotype will occur only if inversion Uab(1) is paternally transmitted. The transformations in males are toward genital arch tissue. For females the transformations are to tissue found on abdominal segment 7 (Ab7) and to structures normally restricted to the genital disc. Ninety-six percent of transformed areas appear on Ab5 and Ab6 in both sexes and on Ab7 in females, coinciding with the Abd-B domain. Four percent of the transformations occurred on Ab1 through Ab4, coinciding with the abd-A domain. The mutant phenotype can be dramatically enhanced by modifying genes such as the posterior BX-C mutant tuh-3. Expressivity is modulated by maternal effect alleles interacting with tuh-3. A region of function within inversion Uab(1) appears to be programmed during spermatogenesis to function in a legacy dependent manner during embryogenesis.     

Seed morphology under SEM and light microscopy in Kansas Juncus (Juncaceae)

Seed morphology was studied in 15 species of four subgenera ofJuncus occurring in Kansas, to determine if seeds provide traits useful in assessing systematic relations within the genus. In this study seed size and shape were of limited value, while surface ornamentation of the hard inner seed coat provided encouraging results. SubgenusPoiophylli showed little variation in surface ornamentation among taxa; similar ornamentation was observed in subgenusGenuini. SubgeneraGraminifolii andSeptati were separately distinct with the taxa in theSeptati forming a continuum of variation.     

Genetic variation of an acid phosphatase (Acp-2) in the laboratory rat: Possible homology with mouse AP-1 and human ACP2

A genetic locus controlling the electrophoretic mobility of an acid phosphatase in the rat (Rattus norvegicus) is described. The locus, designed Acp-2, is not expressed in erythrocytes but is expressed in all other tissues studied. The product of Acp-2 hydrolyzes a wide variety of phosphate monoesters and is inhibited by l(+)-tartaric acid. Inbred rat strains have fixed either allele Acp-2^a or allele Acp-2^b. Codominant expression is observed in the respective F₁ hybrids. Backcross progenies revealed the expected 1:1 segregation ratio. Possible loose linkage was found between the Acp-2 and the Pep-3 gene loci at a recombination frequency of 0.36±0.06.Supported by the Deutsche Forschungsgemeinschaft (Grant Be 352/15) and by a grant from the Alexander-von-Humboldt-Stiftung (VB2-FLF).     

Arbovirological survey in Silica plateau area, Roznava District, Czechoslovakia

The serosurveys conducted in the Silica plateau area of the Slovak karst region revealed the presence of specific neutralizing antibody against tick-borne encephalitis (TBE) virus in 18% of local inhabitants (33 examined, mostly goats and sheep farmers), 54% of goats (26 examined), 18% of sheep (120 examined) and 13% of cattle (60 examined), against Lipovník (LIP) virus in 30% of inhabitants, 88% of goats, 55% of sheep and 45% of cattle, and against Bhanja (BHA) virus in 27% of inhabitants, 46% of goats, 29% of sheep and 23% of cattle. The results of hemagglutination-inhibition tests with TBE and BHA antigens were analogous. A detailed analysis of these serologic data points to a recent enhancement of the circulation of LIP and BHA viruses and to a very low TBE virus activity in this natural focus of arboviral infections. The immunological surveys of the 32 former "Roznava disease" patients, conducted 25 years after an extensive epidemic of a TBE virus infection that originated in Roznava in 1951, revealed the presence of neutralizing (and also hemagglutination-inhibiting) antibodies against TBE virus in as many as 78% of cases. Antibodies against LIP and BHA viruses were also detectable in the sera of 16% and 9%, respectively, of these individuals. Populations of the ectoparasites examined for the presence of arbovirus comprised 231 Ixodes ricinus, 806 Dermacentor marginatus and 204 Haemaphysalis punctata ticks and 117 specimens of the louse-flies Melophagus ovinus. Two strains of arbivirus that were antigenically related to Lipovník and Tribec viruses belonging to a group of Kemerovo viruses were isolated from male and female I. ricinus ticks collected from cattle.     

Effects of beta-endorphin on ornithine decarboxylase in tissues of developing rats: a potential role for this endogenous neuropeptide in the modulation of tissue growth

Ornithine decarboxlyase (ODC) catalyzes the initial step in the bio-synthesis of the polyamines spermidine and spermine, which are key regulators of cell growth, proliferation and differentiation. Intracisternal administration of beta-endorphin (1 microgram) to 6 day-old rats markedly decreased brain, liver, heart and kidney ODC activity. Conversely, subcutaneous administration of beta-endorphin increased ODC activity in the heart and liver. Thus, ODC inhibition in peripheral organs in rat pups given beta-endorphin intracisternally appears to reflect central effects of this neuropeptide. Experiments were also carried out to test whether opioid receptors are involved in these tissue ODC responses. Naloxone prevented the decreases in brain ODC indicating the participation of opioid receptors in that process. In contrast, naloxone did not alter ODC responses in peripheral organs in rat pups given beta-endorphin intracisternally, indicating that these effects are independent of its classical opioid character. These results support the view that endogenous beta-endorphin may play an important role in organogenesis by modulating the growth-related enzyme ODC. The data also suggest that the regulation of peripheral organ development by beta-endorphin may be mediated through the release of growth regulatory substances from the CNS.     

Effects of ultraviolet-B radiation on plants during mild water stress. III. Effects on photosynthetic recovery and growth in soybean

Soybean { Glycine max (L.) Merr. ev. Essex} was grown from seed in a greenhouse under ultraviolet-B (UV-B, 280–320 nm) radiation supplied by filtered FS-40 sunlamps. On a weighted, total daily dose basis these plants received either 0 (control) or 2875 effective J m⁻² day⁻¹ UV-B_BE. When weighted with the generalized plant action spectrum (Caldwell 1971), this simulated the solar ultraviolet-B irradiance expected to occur at College Park, Maryland, USA (39°N) in the event the global stratospheric ozone column is reduced by 23%. The effects of ultraviolet radiation on the photosynthetic recovery from water stress were measured with an infrared gas analyzer. These effects were examined in plants which were either well-watered or previously preconditioned to water stress, during two distinct phenological stages of development. During the early stages of soybean growth, enhanced levels of UV-B reduced net photosynthesis by 25%, and water stress also reduced photosynthesis to nearly the same extent (by 20%). The combination of these two stresses resulted in smaller biomass than that produced by plants exposed to either stress independently. Photosynthesis in older, larger plants was much more sensitive to water stress and was reduced by as much as 50–60% in non-preconditioned plants. Although non-irradiated, non-preconditioned (control) plants recovered to only within 60% of their prestressed value, preconditioned plants recovered to within 70–80% during the 3 day recovery period. Both water stress and UV-B radiation affected non-stomatal conductance, while stomatal conductance was primarily affected by water stress.