Stimulation of the hypothalamic-pituitary-adrenal axis and inhibition of growth hormone release via increased central noradrenaline neuronal activity by urethane anaesthesia in the rat: blockade by clonidine

Computerized gas chromatography-mass spectrometry was used to measure precisely the hypothalamic levels of noradrenaline (NA), dopamine and serotonin together with those of their major neuronal metabolites 3,4-dihydroxyphenylethyleneglycol (DHPG), 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid in normal male rats 45 min after stimulation of hypothalamic-pituitary-adrenal function by urethane (1.3 g/kg) administration. Urethane treatment resulted in a significant elevation of central noradrenergic neuronal activity (NNA) as assessed from marked rises in hypothalamic DHPG concentrations and the ratio (DHPG/NA). At the same time there was significant stimulation of ACTH and corticosterone release and inhibition of growth hormone release. These hormonal and central effects of urethane (but not anesthesia) were inhibited when the alpha 2-agonist clonidine (150 micrograms/kg) was co-administered. Urethane had no major effect on hypothalamic dopamine or serotonin status. We propose that the release of ACTH and the suppression of growth hormone release following urethane anaesthesia is a result of activation of central NNA and suggest that the hormonal responses are mediated via hypothalamic noradrenergic facilitation of corticotrophin releasing factor and somatostatin release to the anterior pituitary.     

The role of mast cell degranulation products in mast cell hyperplasia. I. Mechanism of action of nerve growth factor

A variety of mast cell degranulating agents have previously been shown to induce mast cell hyperplasia in adult rats. In neonates 2.5 S nerve growth factor (NGF) induces a hyperplasia of both mucosal and connective tissue mast cells (MMC and CTMC). We have examined the role of the potent mast cell degranulating properties of NGF on its ability to induce mast cell hyperplasia. Administration of NGF in combination with the mast cell stabilizing agent disodium cromoglycate was found to abrogate the CTMC hyperplasia induced by NGF alone. Treatment of neonatal rats with the alternate degranulating agent compound 48/80 was found to induce a limited CTMC but not a MMC hyperplasia. A supernatant obtained by degranulating purified adult rat peritoneal mast cells with anti-IgE was found to induce hyperplasia of the CTMC population similar to that observed with NGF administration. However, this degranulation product supernatant only induced a limited MMC hyperplasia as judged by RMCP II content of the tissues. These results suggest that NGF has dual action inducing mast cell hyperplasia; CTMC hyperplasia being dependent on the ability of NGF to degranulate mast cells. MMC hyperplasia induced by NGF is independent of CTMC degranulation. Degranulation products from peritoneal mast cells act to increase both MMC and CTMC populations in the neonate. These data suggest that the CTMC population may be regulated by an autocrine positive feedback mechanism in vivo.     

The effect of chlorogenic, gallic and quinic acids on the growth of spoilage strains of Lactobacillus collinoides and Lactobacillus brevis

The naturally occurring complex organic acids, chlorogenic acid, gallic acid and quinic acid, at concentrations of 100, 500 and 1000 mg l^-1 were evaluated for effects on the growth of three spoilage strains of Lactobacillus collinoides and one of Lact. brevis in acid tomato broth containing 5% (v/v) ethanol at pH 4.8. During early stages of growth, all the complex acids at each concentration stimulated growth of Lact. collinoides but not of Lact. brevis. During stationary phase, chlorogenic and gallic acids produced greater cell densities of all strains, whereas quinic acid generally had less effect. The presence of these complex acids in fruit products may increase the requirement for added preservative in order to prevent spoilage by certain strains of lactic acid bacteria.     

Flower senescence in daylily (Hemerocallis)

This paper reviews recent developments in the use of molecular probes for analyzing the genetic makeup of somatic hybrids. Successful application of somatic hybridization to the interspecific transfer of traits encoded in the nucleus is still having limited success. A major difficulty is hybrid infertility, particularly in hybrids between sexually incompatible species. The formation of asymmetric hybrids is being explored as an approach for improving hybrid fertility. Evaluation of the degree of chromosome elimination and chromosome stability and instability in asymmetric hybrids is difficult when the traditional approaches of chromosome counting and isozyme analysis are used. Two new approaches are resolving this difficulty. The use of species-specific repetitive DNA probes in dot blotting and in situ hybridization to chromosomes is providing quantitative data on chromosome elimination and allows detection of translocations. Use of restriction fragment length polymorphism (RFLP) probes for analysis of hybrids between genetically mapped species makes it possible to account for the presence or absence of individual chromosomes and chromosomes arms. Wider use of such molecular probes should greatly improve our understanding of the genetics of both symmetric and asymmetric somatic hybrids and may lead to new strategies for the effective interspecific transfer of nucleus-encoded traits by protoplast fusion.     

Differential response of cycling and noncycling cells to inducers of DNA synthesis and mitosis

The objective of this study was to determine whether cells in G(0) phase are functionally distinct from those in G(1) with regard to their ability to respond to the inducers of DNA synthesis and to retard the cell cycle traverse of the G(2) component after fusion. Synchronized populations of HeLa cells in G(1) and human diploid fibroblasts in G(1) and G(0) phases were separately fused using UV-inactivated Sendai virus with HeLa cells prelabeled with [(3)H]ThdR and synchronized in S or G(2) phases. The kinetics of initiation of DNA synthesis in the nuclei of G(0) and G(1) cells residing in G(0)/S and G(1)/S dikaryons, respectively, were studied as a function of time after fusion. In the G(0)/G(2) and G(1)/G(2) fusions, the rate of entry into mitosis of the heterophasic binucleate cells was monitored in the presence of Colcemid. The effects of protein synthesis inhibition in the G(1) cells, and the UV irradiation of G(0) cells before fusion, on the rate of entry of the G(2) component into mitosis were also studied. The results of this study indicate that DNA synthesis can be induced in G(0)nuclei after fusion between G(0)- and S-phase cells, but G(0) nuclei are much slower than G(1) nuclei in responding to the inducers of DNA synthesis because the chromatin of G(0) cells is more condensed than it is in G(1) cells. A more interesting observation resulting from this study is that G(0) cells is more condensed than it is in G(1) cells. A more interesting observation resulting from this study is that G(0) cells differ from G(1) cells with regard to their effects on the cell cycle progression of the G(2) nucleus into mitosis. This difference between G(0) and G(1) cells appears to depend on certain factors, probably nonhistone proteins, present in G(1) cells but absent in G(0) cells. These factors can be induced in G(0) cells by UV irradiation and inhibited in G(1) cells by cycloheximide treatment.     

Inhibition of activated factor XII by antithrombin-heparin cofactor.

The activation of Factor XII occurs via fragmentation of this zymogen into a diverse spectrum of enzymatically potent molecular species. To study the interaction of antithrombin-heparin cofactor and heparin with activated Factor XII, we have employed two forms of this enzyme with widely differing physical characteristics and biologic potencies. Antithrombin-heparin cofactor was found to be a progressive, time-dependent inhibitor of both forms. The addition of heparin dramatically accelerated the rates of these interactions. Furthermore, sodium dodecyl sulfate gel electrophoresis of reduced proteins has indicated that antithrombin-heparin cofactor functions by forming an undissociable complex with either species of the enzyme. This complex represents a 1:1 stoichiometric combination of activated Factor XII and inhibitor. In the presence of heparin, both species undergo virtually instantaneous complex formation with antithrombin-heparin cofactor without exhibiting alterations in dissociability or stoichiometry.     

Which provenance and where? Seed sourcing strategies for revegetation in a changing environment

Revegetation is one practical application of science that should ideally aim to combine ecology with evolution to maximise biodiversity and ecosystem outcomes. The strict use of locally sourced seed in revegetation programs is widespread and is based on the expectation that populations are locally adapted. This practice does not fully integrate two global drivers of ecosystem change and biodiversity loss: habitat fragmentation and climate change. Here, we suggest amendments to existing strategies combined with a review of alternative seed-sourcing strategies that propose to mitigate against these drivers. We present a provenancing selection guide based on confidence surrounding climate change distribution modelling and data on population genetic and/or environmental differences between populations. Revegetation practices will benefit from greater integration of current scientific developments and establishment of more long-term experiments is key to improving the long-term success. The rapid growth in carbon and biodiversity markets creates a favourable economic climate to achieve these outcomes.