Inhibition of isoproterenol-induced DNA and RNA synthesis in rat parotid and pancreas following removal of submandibular-sublingual glands

Summary [³H] thymidine incorporation into DNA of the parotid (PA) gland of adult and 20-day-old rats and into DNA of the pancreas (PANC) of 20-day-old rats was increased markedly following a 2-day regimen of isoproterenol (ISO) administration. However, when the submandibular-sublingual (SM-SL) glands had been removed just prior to initiation of the ISO injections, the [³H] thymidine incorporation into PA and PANC was inhibited, and cpm/mg protein of these organs was even lower than that of organs of untreated rats with SM-SL glands present. Removal of the PA glands just prior to initiation of the ISO regimen had no effect on the ISO-induced [³H] thymidine incorporation into DNA of PANC but partially inhibited that of the submandibular (SM) gland. It is suggested that the inhibitory effects on DNA and RNA synthesis that follow removal of SM-SL glands are attributable to the growth factors (epidermal growth factor and nerve growth factor) found in the rat SM gland. These factors appear to regulate normal DNA synthetic activity of exocrine glands as well as ₁-adrenoceptor mediated DNA synthesis. Cellular hypertrophy induced by the ISO was less markedly affected by absence of the SM glands, but a partial inhibition of [³H] uridine incorporation into RNA of PA of adult rats also occurred when SM-SL glands were removed prior to initiation of the ISO-regimen.     

Appearance of lectin-binding sites during vascularization of the primordium of the central nervous system in 10 to 12-day-old mouse embryos

Summary In the present study lectin-binding sites were investigated for the lectins Ricinus communis agglutinin (RCA I), wheat germ agglutinin (WGA), soya bean agglutinin (SBA), concanavalin A (Con A), Lotus tetragonolobus(LTA) and Limulus polyphemus agglutinin (LPA) during the initial stages of vasculogenesis of the CNS-anlage in 10 to 12-day-old NMRI mouse embryos. Specific binding sites for the lectins RCA I (sugar specificity: -D-galactose, N-acetylgalactosamine), WGA (sugar specificity: N-acetylglucosamine, sialic acid), and SBA (sugar specificity: N-acetylgalactosamine, -D-galactose) were detected in the newly formed capillaries within the neuroepithelial cell layer. In contrast, binding sites for Con A, LTA and LPA could not be observed at the start of the vascularization of the CNS-anlage. From these results, the conclusion can be drawn that glycoconjugates containing D-galactose, N-acetylgalactosamine and N-acetyl-glucosamine moieties are involved in the early vasculogenesis of the embryonic CNS-anlage of the mouse.     

Seasonal Biotransformation of Naphthalene, Phenanthrene, and Benzo[a]pyrene in Surficial Estuarine Sediments

Transformation rates of naphthalene, phenanthrene, and benzo[a]pyrene in oxidized surficial sediments of a polluted urban estuary, Boston Harbor, Mass., were determined over a period of 15 months. Three sites characterized by muddy sediments were selected to represent a >300-fold range of ambient polycyclic aromatic hydrocarbon (PAH) concentration. Transformation rates were determined by a trace-level radiolabel PAH assay which accounted for PAH mineralization, the formation of polar metabolites, residue, and recovered parental PAHs in sediment slurries. Transformation rates of the model PAHs increased with increasing ambient PAH concentrations. However, turnover times for a given PAH were similar at all sites. The turnover times were as follows: naphthalene, 13.2 to 20.1 days; phenanthrene, 7.9 to 19.8 days, and benzo[a]pyrene, 53.7 to 82.3 days. At specific sites, rates were significantly affected by salinity, occasionally affected by temperature, but not affected by pH over the course of the study. Seasonal patterns of mineralization were observed for each of the PAHs at all sites. The timing of seasonal maxima of PAH mineralization varied from site to site. Seasonal potential heterotrophic activities as measured by acetate and glutamate mineralization rates did not always coincide with PAH mineralization maxima and minima, suggesting that the two processes are uncoupled in estuarine sediments.     

Comparison of chemical analyses of boat and helicopter-collected water samples

Helicopters can be used to collect water samples from many lakes over a wide geographic area within a relatively short time period. Here we report the results from an experiment in which sequential water samples from a lake were collected first from a nonmotorized boat and then immediately afterward from a helicopter. No significant differences were found between the means of the measurement of 20 chemical parameters for the two methods of collection. When compared to obtaining samples from a boat, collection of samples from a helicopter platform had no effect on the content of the water samples.     

A new facultatively nitrite oxidizing bacterium,Nitrobacter vulgaris sp. nov.

A total of 17 facultatively lithoautotrophic strains of Nitrobacter were investigated. They all were found to be related on the species level by DNA hybridizations. The G+C content of DNA ranged between 58.9 and 59.9 mol %. The isolates originated from divers environments. The cells were 0.5–0.8×1.2–2.0 m in size and motile by one polar to subpolar flagellum. Cell-division normally occurred by budding. Polar caps of intracytoplasmic membranes as well as carboxysomes were present. The cells tended to excrete extracellular polymers forming aggregates or biofilms. Heterotrophic growth was slower than mixotrophic but often faster than litoautotrophic growth. In the presence of nitrite and organic substances the organisms often showed diphasic growth. First nitrite and then the organic material was oxidized. In the absence of oxygen growth was possible by dissimilatory nitrate reduction. Nitrite, nitric and nitrous oxide as well as ammonia were formed. Depending on growth conditions the generation times varied from 12 to 140 h. The new Nitrobacter spec. may be one of the most abundant nitrite-oxidizing bacteria in soils, fresh waters and natural as well as artificial stones. For this organism the name Nitrobacter vulgaris is proposed.The type strain is filed with the culture collection of the Institut für Allgemeine Botanik, Universität Hamburg, FRG.     

Glutamate is the endogenous amino acid selectively released by rat hippocampal mossy fiber synaptosomes concomitantly with prodynorphin-derived peptides

The release of endogenous amino acids from depolarized rat hippocampal mossy fiber synaptosomes was investigated to assess the possible role(s) of glutamate and aspartate in mediating the excitatory mossy fiber synaptic input. The relative proportions of prodynorphin-derived peptides concomitantly released with amino acids were also determined to further characterize the biochemical basis for mossy fiber synaptic transmission. Of the 18 amino acids shown to be present in superfusate fractions by liquid chromatographic analysis, only glutamate was released at a significantly enhanced rate from K⁺-stimulated (35 mM KCl) mossy fiber nerve endings. The rates of glutamate and aspartate release were increased by 360±27% and 54±12% over baseline respectively. However, the K⁺-evoked release of glutamate was substantially more Ca²⁺-dependent (80%) than was the release of aspartate (49%). The veratridine (45 M)-evoked release of both acidic amino acids was entirely blocked by 1 M tetrodotoxin. Depolarization (45 mM KCl) also stimulated the release of the four prodynorphin (Dyn) products examined, in a rank order of Dyn B >> Dyn A(1–17) > Dyn A(1–8) >> Dyn A(1–13), with Dyn B efflux increasing by more than 5-fold over baseline values. These results suggest that the predominant excitatory amino acid in hippocampal mossy fiber synaptic transmission may be glutamate and that this synaptic input may be modulated by at least four different products of prodynorphin processing.The animals involved in this study were procured, maintained and used in accordance with the Animal Welfare Act and the Guide for the Care and Use of Laboratory Animals prepared by the Institute of Laboratory Animal Resources—National Research Council.     

Nasal trigeminal responses to toluene presented by an automated delivery system

An apparatus was developed which permits the automated deliveryof volatile chemical stimuli for use in neurophysiology experiments.A computer-controlled olfactometer, incorporating electronicmass flow controllers (EMFCs) and Teflon-lined solenoid valves,generated and delivered clean or odorized air. Neural and respiratorysignals from the animal were amplified and stored, along withtrial information (e.g. odorant concentration) on a chart recorderand video cassette recorder, both of which were controlled bythe computer. This apparatus was used to measure responses totoluene from the rat ethmoid nerve, a part of the ophthalmicdivision of the trigeminal nerve. Multi-unit responses to thiscompound were first observed at 2000 p.p.m. The magnitude ofthe response increased linearly with logarithmic increases inconcentration up to vapour saturation. Changes in respirationin response to toluene also were observed, although neural responsesoften were seen in the absence of respiratory changes.     

Receptors for plant growth regulators: Recent advances

We have reviewed recent progress in research on plant growth regulator (PGR) receptors. For some growth regulators, no receptor protein has yet been identified, but promising new approaches are discussed. For other receptors, specific and sensitive probes have been developed and, in one case, the membrane-associated auxin-binding protein of maize, these have been used to study the function of the receptor. The maize receptor has been cloned and sequenced; cDNA probes will allow the expression of receptor genes in normal and transformed plants to be studied. PGR sensitivity mutants have been described and, in conjunction with biochemical probes, should prove valuable in elucidating the functions of receptors and the nature of subsequent signal transduction events.     

Transformation of cotton (Gossypium hirsutum L.) via particle bombardment

Embryogenic suspension cultures of cotton (Gossypium hirsutum L.) were subjected to particle bombardment, where high density particles carrying plasmid DNA were accelerated towards the embryogenic plant cells. The plasmid DNA coating the particles encoded hygromycin resistance. One to two weeks following bombardment, embryogenic cotton cells were placed in proliferation medium containing 100 g/ml hygromycin. Clumps of tissue which grew in the presence of hygromycin were subcultured at low density into fresh hygromycin-containing proliferation medium. Following sequential transfer of embryogenic tissue to development and then germination media, plants were recovered from transgenic embryogenic tissue. Southern hybridization confirmed the presence of the hygromycin resistance gene in embryogenic suspension culture tissue and regenerated plants.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - GUS -glucuronidase - Aph IV aminoglycoside phosphotransferase type IV Salaries and research support were provided by State and Federal funds appropriated to OSU/OARDC and USDA-ARS. Mention of trademark or proprietary products does not constitute a guarantee or warranty of the product by OSU/OARDC or USDA, and also does not imply approval to the exclusion of other products that may also be suitable. Journal Article No. 354-89