Effects of nitrous oxide on mitochondrial and cell respiration and growth in Distichlis spicata suspension cultures

The reversible inhibition of respiratory activity could provide a novel approach to the preservation of traditionally hard to store plant germplasm such as clonal materials and recalcitrant seed. The gaseous anesthetic nitrous oxide caused a reversible, dose-dependent, partial inhibition of dioxygen utilization in mitochondrial particles isolated from cell suspension cultures of the salt-tolerant marsh grass Distichlis spicata, with maximal inhibition of 33% after 30 minutes exposure to an atmosphere of 80% nitrous oxide plus 20% oxygen. Respiration of whole cells required longer time to be affected by the anesthetic, and was reversibly inhibited an average of 19% when measured using a differential respirometer. Exposure to 80% nitrous oxide plus 20% oxygen for up to 10 days caused no measurable effect on cell growth.Abbreviations PCV packed cell volume - EDTA sodium ethylenediaminetetraacetic acid - BSA bovine serum albumin - MOPS 3(N-morpholino) propanesulfonic acid - TMPD N,N,N',N'-tetramethyl-p-phenylene diamine - STP standard temperature and pressure     

Conversion of human plasma high density lipoprotein-2 to high density lipoprotein-3. Roles of neutral lipid exchange and triglyceride lipases

Cholesterol esters accumulating in human plasma high density lipoproteins (HDL) are important in conversion of HDL3 to larger HDL2. We studied whether mechanisms of removal of cholesterol esters from HDL might be important in a reverse direction, i.e. conversion of HDL2 to HDL3. Native HDL2 or HDL3 is incubated with very low density lipoproteins (VLDL) and lipoprotein-poor plasma (d greater than 1.21 g/ml) at 37 degrees C. After incubation, "modified" (M) VLDL, and HDL2 or HDL3 are reisolated by ultracentrifugation. In modified M-HDL2 or M-HDL3, triglyceride becomes the major core lipid as the triglyceride/cholesterol ester weight ratio increases 8-10-fold relative to native HDL. With only small changes in protein/phospholipid ratios in M-HDLs, the large decrease in cholesterol ester/protein ratios suggest net cholesterol ester loss from HDL. Quantitative recovery analyses prove that the cholesterol esters lost from HDL are transferred to M-VLDL, which is now richer in cholesterol ester and poorer in triglyceride. These substantial exchanges of HDL lipids are not associated by significant transfer of HDL apoproteins but are dependent on neutral lipid transfer factors present in human lipoprotein-poor plasma (d greater than 1.21 g/ml). Similar results are obtained when purified core lipid transfer protein replaces d greater than 1.21 g/ml plasma in these incubations. After depletion of cholesterol ester from HDL, most but not all, exchanged triglyceride can be removed by lipolysis with either hepatic or lipoprotein lipase, resulting in a post-lipolysis HDL2 with an increased triglyceride content relative to normal HDL. With successive incubations with VLDL, and core lipid transfer factors, HDL2 loses more than two-thirds of its cholesterol esters. After lipolysis of acquired triglyceride, HDL2 is remodeled, in both composition and flotation parameters, toward HDL3.     

Predictors of success in hypertensives treated with biofeedback-assisted relaxation

This paper describes differences in response in seventeen patients with essential hypertension who participated in a treatment program consisting of electromyograph biofeedback assisted relaxation training. Responders were found to have higher treatment values of urinary and plasma cortisol, Trait Anxiety and forehead muscle tension compared to treatment failures. Responders also sustained greater decreases in plasma, and urinary cortisol after treatment. These data are discussed in light of the ability to predict which hypertensive patients may be most benefitted by a relaxation based treatment.We would like to thank Dr. Charles Spielberger for his permission to use the State-Trait Anxiety Inventory. We thank Michael Robinson for assistance with statistical analysis.     

Respiratory resistance with histamine challenge by single-breath and forced oscillation methods

Relaxed expirations were obtained from five anesthetized dogs under control conditions and during various rates of intravenous infusion of histamine. All volume vs. time curves obtained from 20 ms to 2 s after the start of expiration were poorly described by a single exponential function but were fitted very well by a biexponential function. The resistance of the respiratory system as a function of frequency from 2 to 26 Hz was also determined by the forced oscillation method in the same dogs. Three two-compartment models of the respiratory system were identified from the exponentials fitted to the relaxed expiration data, and the one that had the most plausible parameter values under control conditions consisted of a homogeneous lung compartment connected to a viscoelastic compartment. Although a two-compartment model is arguably appropriate for describing relaxed expirations in normal dogs, physiological considerations suggest that there should be more than two interacting components with histamine infusion. We cannot identify all these components from our data, however. The equivalent complex impedance of the respiratory system was also calculated from the biexponential curves and showed significant variation in resistance over the frequency range from 0 to 2 Hz and negligible variation above 2 Hz. The calculated resistances at 2 Hz were consistently higher than those obtained by the forced oscillation method, which may be due to the nonlinear behavior of the respiratory system during relaxed expiration. We conclude that the single-breath and forced oscillation methods should be viewed as providing complimentary information about respiratory resistance.     

Conserved Nodulation Genes in Rhizobium meliloti and Rhizobium trifolii

Plasmids which contained wild-type or mutated Rhizobium meliloti nodulation (nod) genes were introduced into Nod⁻R. trifolii mutants ANU453 and ANU851 and tested for their ability to nodulate clover. Cloned wild-type and mutated R. meliloti nod gene segments restored ANU851 to Nod⁺, with the exception of nodD mutants. Similarly, wild-type and mutant R. meliloti nod genes complemented ANU453 to Nod⁺, except for nodCII mutants. Thus, ANU851 identifies the equivalent of the R. meliloti nodD genes, and ANU453 specifies the equivalent of the R. meliloti nodCII genes. In addition, cloned wild-type R. trifolii nod genes were introduced into seven R. meliloti Nod⁻ mutants. All seven mutants were restored to Nod⁺ on alfalfa. Our results indicate that these genes represent common nodulation functions and argue for an allelic relationship between nod genes in R. meliloti and R. trifolii.     

Isolation of pituitary fibroblast growth factor by fast protein liquid chromatography (FPLC): partial chemical and biological characterization

Bovine pituitary fibroblast growth factor has been purified 222,000-fold to homogeneity by a combination of differential salt extraction, gel filtration, and ion exchange chromatography on Mono S column. Pituitary FGF is a single-chain polypeptide with an apparent molecular mass of 15,800 and an isoelectric point of 9.6. It is highly active in triggering the proliferation of bovine and human vascular endothelial cell [half-maximal stimulation at 23-40 pg/ml (1.5-2.6 pM) and saturation between 140 and 280 pg/ml (9.3-18.6 pM)]. It displays a similar activity on bovine vascular smooth muscle cells, corneal endothelial cells, granulosa and adrenal cortex cells, and rabbit costal chondrocytes.     

Physiological and isotopic aspects of photosynthesis in peperomia

Physiological and isotopic aspects of several Peperomia species were investigated. All but one species had C₃-like stomatal behavior, in that stomata were open during the day and closed during the night. In these species, most atmospheric CO₂ uptake occurred during the day. Concurrent with this stomatal behavior, there were Crassulacean acid metabolism-like acid fluctuations in most species. Carbon and hydrogen isotope ratios of cellulose nitrate from Peperomia reflect their physiological behavior. The δ¹³C values of cellulose nitrate from Peperomia species were similar to values observed in C₃ plants and consistent with the daytime uptake of exogeneous CO₂ via the C₃ photosynthetic pathway. The δD values of cellulose nitrate from Peperomia species approach those of Crassulacean acid metabolism plants. These elevated δD values are caused by fractionations occurring during biochemical reactions and not as a consequence of water relations.     

Inhibition of chlorophyll synthesis inHordeum vulgare by 3-amino 2,3-dihydrobenzoic acid (gabaculin)

Gabaculin (3-amino 2,3-dihydrobenzoic acid) is shown to be a very potent inhibitor of chlorophyll formation inHordeum vulgate. Exposure of leaf segments to 30/M gabaculin results in an 80% inhibition of chlorophyll synthesis, and this is paralleled by a decrease in carotenoid. Dual-inhibitor studies with dioxoheptanoic acid, which is an inhibitor of inolaevulinic acid dehydratase, show that gabaculin inhibits an earlier step than dioxoheptanoic acid and affects -aminolaevulinic acid synthesis rather than its subsequent metabolism.     

Sample preconditioning for measurement of fluorescence induction of chlorophyll a in marine phytoplankton

Conditions for measuring fluorescence induction curves (time-scalems) of in vivo chlorophyll ^a were studied using cultures ofDunaliella tertiolecta Butcher (Chlorophyceae) and of Thalassiosirapseudonana Hustedt (3H) (Bacillariophyceae), and samples ofnatural phytoplankton populations from the Grand Banks. Thearea above the fluorescence induction curve (A_DCMU) and themaximum fluorescence intensity (F_max) measured in the presenceof 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU) were computedby microcomputer. Cells must be ‘conditioned’ or‘adapted’ prior to obtaining a fluorescence inductioncurve; dark-adaptation resulted in a lower A_DCMU and F_max thandid adaptation in far-red (720 nm) light, and was the conditioningmethod chosen. A_DCMU and F_max increased linearly with increasingirradiance up to 32.8 W m^–2 the highest actinic irradianceavailable. Information on the light history of D. tertiolectawas obtained by following the time-course of change in A_DCMUand in F_max for cells exposed for 10 min to far-red or to bluelight. The rise-time of the fluorescence induction curve andvalues of F_max were greater for samples of D. tertiolecta concentratedonto glass-fiber filters than for liquid samples, however, valuesof A_DCMU for filtered and liquid samples were not significantlydifferent. Samples of Grand Banks phytoplankton collected ontoglass-fiber filters and frozen for 28 d exhibited a significantdecrease in F_max and in A_DCMU relative to the same freshly-filteredsamples. Filtration and freezing of samples is not recommended. ^*This paper is the result of a study made at the Group for AquaticPrimary Productivity (GAP). Second International Workshop heldat the National Oceanographic Institute. Haifa. Israel in April–May1984.     

Restriction fragment polymorphisms as probes for plant diversity and their development as tools for applied plant breeding

Summary Maize and tomato cDNA clones have been hybridized in Southern blotting experiments to plant genomic DNA prepared from different lines to detect restriction fragment polymorphisms (RFPs). In maize we have found that a high degree of genetic variability is present, even among domestic inbred lines. Most randomly chosen maize cDNA clones can be used to detect elements of this variability. Similar levels of polymorphism are observed when genomic DNA is digested with any of a number of different restriction enzymes and probed with individual clones. When a clone is hybridized to genomic DNAs prepared from several different maize lines, a number of different alleles are often detected at a single locus. At the same time one clone can often detect more than one independently segregating locus by cross hybridization to related sequences at other loci. As expected these markers are inherited as simple codominant Mendelian alleles from one generation to the next and colinkage of these markers can be demonstrated in the progeny from a heterozygous parent. In similar studies with tomato, remarkably different results were found. Few RFPs were demonstrable among domestic Lycopersicon esculentum lines although a higher level of variability could be detected when comparing esculentum with its wild Lycopersicon relatives. These results are discussed in relation to the applied uses of RFPs in plant breeding as well as the inherent variability of different plant genomes.This work was supported in part by funds from Sandoz Ltd. (Basel, Switzerland) and its subsidiary company, Northrup King Co. (Minneapolis, Minn., U.S.A.) as well as by NSF SBIR grant #BSR-8360870.