Monoamine Neurotransmitter Metabolism and Locomotor Activity During Chemical Hypoxia

The effects of hypoxia on metabolism of 5-hydroxytryptamine (5-HT or serotonin) and 3,4-dihydroxyphenylethylamine (DA or dopamine) were compared with those on open-field activity in male CD-1 mice. Chemical hypoxia was induced with NaNO2. Hypoxia did not alter striatal concentrations of DA, 5HT, Trp, Tyr, 5-hydroxyindoleacetic acid, or homovanillic acid. However, NaNO2 (75 mg/kg) reduced the rates of conversion of [3H]Tyr to [3H]DA (-41%) and [3H]Trp to [3H]5-HT (-39%). Hypoxia also reduced dihydroxyphenylacetic acid (DOPAC) levels (-27%) and DOPAC/DA ratios (-20%). Open-field behavior, as measured in an automated activity monitor, decreased in a dose-dependent fashion with 75-150 mg/kg of NaNO2 (-35 to -90%). Comparison with previous studies suggests that the syntheses of dopamine, serotonin, and the amino acids are equally vulnerable to hypoxic insults but may be less sensitive than the synthesis of acetylcholine.     

Identification and characterization of a major early cytomegalovirus DNA-binding protein

We characterized a DNA-binding protein with an approximate molecular weight of 129,000 (DB129) which is present in the nuclei of cytomegalovirus- (strain Colburn) infected cells, but not in virus particles. Results of two types of experiments demonstrated that DB129 is a member of the early class of herpesviral proteins. First, time course pulse-labeling experiments showed that its synthesis begins after that of the immediate-early protein IE94, but prior to the appearance of late viral proteins, and was reduced at late times. Second, in the presence of inhibitors of viral DNA replication, DB129 continued to be made and accumulated to elevated levels. A second set of experiments showed that DB129 bound to single-stranded DNA in vitro and was eluted by a NaCl gradient in two peaks, one at about 0.2 M and the second at about 0.6 M. A similar pattern of release was observed when infected-cell nuclei were serially extracted with increasing NaCl concentrations. In addition, treatment of nuclei with DNase I selectively released DB129, along with a small but significant fraction of another DNA-binding protein, DB51. These results suggest that DB129 is associated with DNA in vivo and that it interacts directly with single-stranded DNA. It was also shown that cells infected with human cytomegalovirus (strain Towne) contain a slightly larger counterpart to DB129, which was designated DB140. Similarities between these proteins and the major DNA-binding protein of herpes simplex virus are discussed.     

Characterization of phosphoproteins and protein kinase activity of virions, noninfectious enveloped particles, and dense bodies of human cytomegalovirus.

Phosphorylation of the proteins of human cytomegalovirus (CMV) virions, noninfectious enveloped particles (NIEPs), and dense bodies was investigated. Analyses of particles phosphorylated in vivo showed the following. Virions contain three predominant phosphoproteins (i.e., basic phosphoprotein and upper and lower matrix proteins) and at least nine minor phosphorylated species. NIEPs contain all of these and one additional major species, the assembly protein. Dense bodies contain only one (i.e., lower matrix) of the predominant and four of the minor virion phosphoproteins. Two-dimensional (charge-size) separations in denaturing polyacrylamide gels showed that the relative net charges of the predominant phosphorylated species ranged from the basic phosphoprotein to the more neutral upper matrix protein. In vitro assays showed that purified virions of human CMV have an associated protein kinase activity. The activity was detected only after disrupting the envelope; it had a pH optimum of approximately 9 to 9.5 and required a divalent cation, preferring magnesium to manganese. In vitro, this activity catalyzed phosphorylation of the virion proteins observed to be phosphorylated in vivo. Peptide comparisons indicated that the sites phosphorylated in vitro are a subset of those phosphorylated in vivo, underscoring the probable biological relevance of the kinase activity. Casein, phosvitin, and to a minor extent lysine-rich histones served as exogenous phosphate acceptors. Arginine-rich and lysine-rich histones and protamine sulfate, as well as the polyamines spermine and spermidine, stimulated incorporation of phosphate into the endogenous viral proteins. Virions of all human and simian CMV strains tested showed this activity. Analyses of other virus particles, including three intracellular capsid forms (i.e., A, B, and C capsids), NIEPs, and dense bodies, indicated that the active enzyme was not present in the capsid. Rate-velocity sedimentation of disrupted virions separated the protein kinase activity into two fractions: one that phosphorylated exogenous casein and another that phosphorylated primarily the endogenous virion proteins.     

The kinetics of the reactions of Parasponia andersonii hemoglobin with oxygen, carbon monoxide, and nitric oxide

Hemoglobin I was isolated from nodules formed on the roots of Parasponia andersonii inoculated with Rhizobium strain CP 283. The rate of oxygen dissociation from Parasponia hemoglobin increases about 12-fold between pH 4 and 7, with apparent pK 6.4, to reach a limiting value of 14.8s-1. The optical spectrum of oxyhemoglobin in the visible region is also dependent on pH with pK near 6.4. The rate constant for oxygen combination with Parasponia hemoglobin increases about 7-8-fold between pH 4 and 7, with apparent pK 5.37, to reach a value of 1.67 X 10(8) M-1 s-1 at pH 7. The optical spectrum of deoxyhemoglobin in the visible region and the rate constant for carbon monoxide combination are also dependent on pH with apparent pK 5.65 and 5.75, respectively. The rate constant for carbon monoxide dissociation is independent of pH. The oxygen affinity of Parasponia hemoglobin, P50 = 0.049 torr at 20 degrees C, calculated from the kinetic constants at pH 7, is very great. At alkaline pH there is a prominent geminate reaction with oxygen and nitric oxide, with both subnanosecond and tens of nanosecond components. These reactions disappear at acid pH, with pK 6.4, and the effective quantum yield is reduced. In general, the reactions of Parasponia hemoglobin with oxygen and carbon monoxide resemble those of soybean leghemoglobin. In each, great oxygen affinity is achieved by unusually rapid oxygen combination together with a moderate rate of oxygen dissociation. We suggest that protonation of a heme-linked group with pK near 6.4 controls many properties of Parasponia oxyhemoglobin, and protonation of a group with pK near 5.5 controls many properties of Parasponia deoxyhemoglobin.     

Community pattern analysis: A method for quantifying community mosaic structure

A method of quantifying community spatial patterns, community pattern analysis, is described. It is proposed that ordination analysis is used to obtain an integrated score for each quadrat from transect data. For the data presented here, separate ordinations were made of both floristic and environmental (soils) data. The ordination axis scores are then analysed using two or three-term local variance analysis to quantify the scales of community pattern. Correlation analyses allow the relationship between the vegetation and soils data (as represented by ordination axis scores), and other environmental data to be investigated at defined scales. The advantages of this method, that employs the joint application of conventional methods, are that it includes the influence of all species in the analysis, and that multiple uncorrelated scales of pattern within a community are identified.     

Immunoaffinity isolation of apolipoprotein E-containing lipoproteins

Discrete apolipoprotein E-containing lipoproteins can be identified when EDTA plasma is fractionated on columns of 4% agarose. The present study has demonstrated, by physical and metabolic criteria, that these apolipoprotein E-containing lipoprotein subclasses may be further isolated by immunoaffinity chromatography. Whole plasma was first bound to an anti-apolipoprotein E immunoadsorbent prior to gel filtration on 4% agarose. After elution from the affinity column and dialysis, the bound fraction was chromatographed on 4% agarose. Discrete subfractions of apolipoprotein E could be demonstrated within elution volumes similar to those observed in the original plasma. When whole plasma was first submitted to gel filtration and the apolipoprotein E-containing lipoproteins of either intermediate- or of high-density lipoprotein (HDL) size were subsequently bound to anti-apolipoprotein E columns, the bound eluted fractions maintained their size and physical properties as shown by electron microscopy and by rechromatography on columns of 4% agarose. The metabolic integrity of apolipoprotein E-containing very-low-density lipoproteins (VLDL) was examined by coinjection into a cynomolgus monkey of 125I-labeled apolipoprotein E-rich and 131I-labeled apolipoprotein E-deficient human VLDL which had been separated by immunoaffinity chromatography. The plasma specific activity time curves of the apolipoprotein B in VLDL, intermediate-density (IDL) and low-density (LDL) lipoproteins demonstrated rates of decay and precursor-product relationships similar to those obtained after injection of whole labeled VLDL, supporting the metabolic integrity of VLDL isolated by immunoaffinity chromatography.     

Characterization of some East African Theileria species isolates by isoenzyme analysis, with particular reference to T. parva

Eight different isolates of Theileria parva and one isolate of T. taurotragi, in the form of intra-lymphocytic schizonts and/or purified piroplasms, were subjected to isoenzyme analysis for 24 enzymes by both isoelectric focusing in agarose and electrophoresis in starch gel. Twelve enzymes distinguished between T. parva and T. taurotragi; five enzymes (HK, GPI, PEP1, LDH and SOD) showed variations within T. parva. The metabolism of the host cell was affected by schizont infection, which masked intraspecific variations. Piroplasms were of more potential value for characterization of T. parva.     

Ovulation rate and inhibin levels in gonadotrophin-treated mice

Ovarian follicular growth was induced in immature female mice with varying doses of pregnant mare's serum gonadotrophin. The numbers of ovulations were determined either by counting tubal oocytes or corpora lutea in the ovary. Ovarian and circulatory levels of inhibin rose progressively with increasing doses of PMSG and a positive correlation (P less than 0.01) was found between circulating inhibin levels and ovulation rate. The latter correlation makes it likely that the growing preovulatory ovarian follicles are the predominant source for the secretion of inhibin into the circulatory system.     

Biomass: Is it a useful tool in paleocommunity reconstruction?

In general, more of the biomass of the community is preserved than is its numerical abundance. Thus, the paleontologist, on the average, works with more of the community when biomass is used. Community characteristics such as taxon dominance and habitat proportions are at least as accurately derived from biomass as numerical abundance. The use of biomass is clearly more appropriate in describing energy flow and trophic proportions. Whenever possible, biomass should be used as a complement to numerical abundance in future paleoecologic reconstructions.