Pelargonium zonate spot virus is transmitted vertically via seed and pollen in tomato.

In autumn 2007, a new disease with unknown etiology was observed in open-field tomato (Solanum lycopersicum) in the Lachish region of Israel. The symptoms included mild mosaic, leaf malformation, and severe stunting of the plants. The causal agent was readily transmitted mechanically from the sap of infected plants to indicator plants. Viral particles were purified from infected plants and cDNA was synthesized from RNA isolated from the particles. Cloning and sequencing of the cDNA showed 95% identity to RNA 3 of Pelargonium zonate spot virus (PZSV). Using reverse-transcription polymerase chain reaction, PZSV was detected in both seed and pollen grains of infected tomato plants. Attempts to disinfect seed by using hydrochloric acid and trisodium phosphate failed to eliminate this PZSV detection. Seed from infected tomato plants gave rise to infected seedlings with a seed-transmission rate of PZSV of 11 to 29%. Pollen grains collected from flowers of infected plants were used to hand pollinate healthy mother tomato plants. Although none of the pollinated mother plants became infected with PZSV, 29% of the seedlings produced from seed harvested from these plants were found to be infected. This is the first demonstration that PZSV is transmitted vertically via both pollen and seed in tomato plants.

Relationship between blood, liver and brain pyridoxal phosphate and pyridoxamine phosphate concentrations in mice.

Plasma pyridoxal 5'-phosphate (PLP) concentrations are considered to be the most reliable single indicator of vitamin B-6 nutritional status and are thought to reflect tissue PLP and pyridoxamine 5'-phosphate (PMP) levels. We investigated the relationship between dietary level of pyridoxine hydrochloride (PN-HCl) and concentrations of PLP in blood and PLP and PMP in liver and brain of mice. Female heterogeneous stock mice, 60 to 90 d old, were fed purified diets containing 0.5, 1.0, 2.0, 3.0, 5.0, or 7.0 mg PN-HCl/kg diet for 5 wk. PLP and PMP concentrations were determined by a spectrophotometric apotryptophanase assay. PLP content of plasma, erythrocytes, whole blood, liver and brain and PMP levels in liver and brain were highly correlated with dietary level of PN-HCl (r values ranged from 0.81 to 0.94, n per correlation = 32 to 43). By using the entire range of dietary levels of PN-HCl, both plasma and erythrocyte PLP were found to be significantly correlated with tissue PLP and PMP concentrations. For any one dietary level, however, correlations between plasma or erythrocyte PLP and tissue PLP and PMP concentrations were low and nonsignificant. These results suggest that plasma PLP levels may be suitable to determine vitamin B-6 status of populations, but not to reliably predict tissue concentrations of PLP or PMP in individuals.

Strain, sex and developmental profiles of cocaine metabolizing enzymes in mice.

Cocaine is a potent hepatotoxin in laboratory mice, although the cocaine-induced hepatotoxicity (CIH) is due to the action of a metabolite of cocaine. Cocaine can be hydrolyzed by serum cholinesterase (ChE) to inactive products, or be oxidized by hepatic cytochrome P-450 and FAD-containing monooxygenase (FADM). The oxidative pathway is thought to be responsible for production of the hepatotoxic metabolite of cocaine, presumably norcocaine nitroxide. Female mice are much more resistant to CIH than males of the same strain. We have found that immature male mice are as resistant as females to the development of CIH. Males did not show any CIH until the onset of puberty (30 days of age), indicating that the development of CIH in males was under hormonal control. To determine if the major cocaine-metabolizing enzymes were responsible for the regulation of CIH, we measured the activities of ChE, cocaine N-demethylation (CND) and FADM as a function of sex in C57BL/6Ibg and DBA/2Ibg mice 20-21, 30 +/- 1 and 65 +/- 5 days of age. There was a significant sex difference in ChE activity (females higher than males) but no effect of age. Cocaine N-demethylation increased in both males and females with age, but there was no consistent sex difference. Activity of FADM declined in males as a function of age, but remained constant in females. The lack of a consistent correlation between enzyme activities and sex-, strain-, and age-dependent differences in susceptibility to CIH, do not support a regulatory role for ChE, CND or FADM in mediating the hepatotoxic response.

Vitamin B-6 metabolic enzymes in blood and placenta of pregnant mice.

Plasma pyridoxal 5'-phosphate (PLP) concentrations decrease 50% in pregnant mice and erythrocyte PLP levels increase threefold over nonpregnant levels. These studies were designed to determine whether changes in the enzymes involved in synthesis and degradation of PLP in blood are altered during pregnancy. We measured net synthesis of PLP in erythrocytes and the activity of enzymes involved in the regulation of plasma and erythrocyte PLP concentration: erythrocyte pyridoxal kinase (PLK) and neutral phosphatase, and plasma and tissue alkaline phosphatase (ALP). Net synthesis of PLP and activities of erythrocyte PLK and neutral phosphatase in erythrocytes remained unchanged during pregnancy. We were unable to detect any dephosphorylation of PLP in erythrocytes of pregnant or nonpregnant mice. Mouse erythrocytes were devoid of ALP activity; neutral phosphatase was inactive with PLP and PLP was an uncompetitive inhibitor of the enzyme. Plasma ALP activity decreased 50% in the pregnant mice; therefore, it likely does not participate in the reduction of plasma PLP levels during pregnancy. Placenta had high levels of PLP-phosphatase activity (ALP) and, if it is active as an ectoenzyme in this tissue as it is in others, it may be the most important mediator of plasma PLP levels in pregnancy.

Pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate concentrations in blood and tissues of mice fed ethanol-containing liquid diets.

The effects of chronic ethanol administration on vitamin B-6 metabolism were studied in female Long-Sleep (LS) and Short-Sleep (SS) mice. Animals were fed an ethanol containing liquid diet (AIN-76) for four weeks. Concentration of ethanol in the diet increased from 10 to 25% ethanol-derived calories (EDC) during weeks 1-3 and was maintained at 30% EDC for 1 additional week. We measured concentrations of pyridoxal 5'-phosphate (PLP) in plasma, erythrocytes and whole blood, and liver and brain PLP and pyridoxamine 5'-phosphate (PMP) in ethanol-fed and pair-fed control mice. Chronic ethanol administration significantly increased PMP and total (PLP + PMP) levels in the liver of SS mice. In LS mice ethanol feeding significantly decreased PMP and total (PLP + PMP) levels in the brain, but these values were still within normal limits. These results suggest that both control and ethanol-containing liquid diets are nutritionally adequate with respect to vitamin B-6, and that chronic ethanol administration does not adversely affect vitamin B-6 metabolism in adult mice.

Changes in pyridoxal phosphate and pyridoxamine phosphate in blood, liver and brain in the pregnant mouse.

A decrease in plasma pyridoxal-5'-phosphate (PLP) occurs during pregnancy in humans and experimental animals for reasons that are not known. To determine if mice also develop decreased plasma PLP concentrations during pregnancy, and if plasma PLP levels in pregnancy reflect tissue levels of PLP and pyridoxamine-5'-phosphate (PMP), we measured PLP concentrations in plasma, erythrocytes and whole blood, and liver and brain PLP and PMP in control and pregnant mice. Mice were fed a nonpurified diet containing 8.13 mg pyridoxine-HCl/kg. The PLP analyses were performed in our newly developed apotryptophanase method in which the substrate S-benzyl-L-cysteine is hydrolyzed to benzyl mercaptan, reacted with Ellman's reagent and measured spectrophotometrically. During pregnancy, plasma PLP levels decreased 50% below control levels, but erythrocyte and whole blood PLP levels increased 2.9- and 1.6-fold, respectively. Liver PLP and PMP decreased 25%, in parallel with plasma PLP, but brain PLP and PMP concentrations were unchanged during pregnancy. These results suggest that metabolism or utilization of vitamin B-6 is altered in pregnancy, and that plasma PLP concentrations alone may not be a good indicator of nutritional status in pregnancy.

Salt hunger in the rhesus monkey.

Five rhesus monkeys (Macaca mulatta) were placed on a low-sodium diet and given injections of furosemide in order to promote sodium loss. The results indicated that these methods elicit a substantial and specific salt hunger. Issues surrounding salt hunger are discussed.

[Comparative study of D-glyceraldehyde-3-phosphate dehydrogenase from frog and pike skeletal muscles]. / Sravnitel'noe izuchenie svoistv D-glitseral'degid-3-fosfatdegidrogenaz iz skeletnykh myshts liagushki i shchuki.

The purified preparations of glyceraldehyde-3-phosphate dehydrogenase isolated from frog and pike skeletal muscles were found homogenous under polyacrylamide gel electrophoresis. Their amino acid composition is similar to that of glyceraldehyde-3-phosphate dehydrogenase from other animal species. The interaction kinetics for frog and pike glyceraldehyde-3-phosphate dehydrogenase SH-groups with 5,5'-dithio-bis-(2-nitrobenzoate) (DTNB) were studied. A negative correlation between the thermal stability of the enzyme preparations from pig, pike, lamprey and frog muscles and the reactivity of their SH-groups with respect to DTNB was observed. NAD at saturating concentrations was found to protect the enzyme from lower vertebrates muscles against thermal inactivation in a lesser degree than does the pig muscle enzyme. The weaker protective effect of NAD was observed for lamprey and frog enzyme preparations, which are characterized by a low SH-group reaction ability. Frog and pike apoenzymes are considerably more resistant to trypsin proteolysis than the pig apoenzyme.

[Effect of coenzyme on conformational stability of glyceraldehyde-3-phosphate dehydrogenase from muscles of ecto- and endothermic animals]. / Vliianie kofermenta na konformatsionnuiu stabil'nost' glitseral'degid-3-fosfatdegidrogenazy iz myshts ekto-i endotermnykh zhivotnykh.

The stabilizing effect of the coenzyme (NAD) on the structure of glyceraldehyde-3-phosphate dehydrogenase from lamprey and porcine muscles with respect to proteolysis and heat denaturation was studied. The process of heat denaturation was followed by the changes in specific activity of the enzymes; that of proteolysis--by the changes in specific activity and circular dichroism. It was shown that in both cases NAD at saturating concentration exerts a far weaker stabilizing effect on the structure of glyceraldehyde-3-phosphate dehydrogenase from lamprey muscle than on that of the porcine muscle enzyme. The coensyme-dependent stabilization of lamprey muscle glyceraldehyde-3-phosphate dehydrogenase does not differ from that of mammalian muscle enzyme. Possible interrelationship between the phenomenon observed and the molecular mechanism of thermal adaptation in the cold-blooded animals is discussed.

[Concentration and properties of the SH-groups of glyceraldehyde-3-phosphate dehydrogenase from the muscles of the lamprey Lampetra fluviatilis]. / Soderzhanie i svoistva SH-grupp glitseral'degid-3-fosfatdegidrogenazy iz myshts minogi Lampetra fluviatilis.

SH-groups of glyceraldehyde-3-phosphate dehydrogenase (GAPD) from lamprey muscle were investigated by Ellman's technique [4]. Three SH-groups per 1 monomer were determined in the presence of 8 M urea. The kinetics of the reaction of SH-groups of lamprey GADP with DTNB in non-denaturating conditions is intermediate between that of GAPD from mammalian muscles and sturgeon muscles, resembling the kinetics of SH-groups of the enzyme from halibut muscles.

[Study of conformational transformations in serum albumin by the method of scanning microcalorimetry]. / Issledovanie konformatsionnykh prevrashchenii syvorotochnogo al'bumina metodom skaniruiushchei mikrokalorimetrii

Thermal denaturation of serum albumin in the alkali pH region is investigated by the scanning microcalorimetry method. It is shown that at pH 8.5 a macromolecule undergoes a conformational transformation as a result of which its thermal characteristics are changed qualitatively. The form which corresponds to lower pH values is denatured according to the smaller than all or none greater than model with an intensive sorption of heat. The form corresponding to higher pH values is denatured noncooperatively without heat absorption but with an essential increase of heat capacity.