Antimicrobial terpenoids of Gossypium: Hemigossypol, 6-methoxyhemigossypol and 6-deoxyhemigossypol

The sesquiterpenoid aldehydes, hemigossypol (1a), 6-methoxyhemigossypol (1b), and 6-deoxyhemigossypol (1c), were isolated and identified from Verticillium-infected stele tissue of Gossypium barbadense. Structures were established by spectral (UV, IR, NMR, MS) evidence and chemical transformations. This is the first report of (1b) and (1c) in nature, and of NMR and m.p. data for crystalline pure (1a). Compound (1a) occurred in diseased stele tissues of all 21 Gossypium species examined and in the genera, Cienfuegosia, Gossypioides, Hampea, and Thespesia; it was absent in three Hibiscus spp. Compound (1b) occurred in the same taxa as (1a), except that it was absent in species of two cytogenetic groups (A and B genome) of Gossypium. Compound (1c) occurred in trace quantities, or was not detected, in most species; however, its distribution appeared to besimilar to that     

Chromosomal abnormalities in maternal and fetal tissues of magnesium- or zinc-deficient rats.

The effect of dietary deficiency during pregnancy of zinc or magnesium on maternal and fetal chromosomes was studied. Pregnant rats were given a zinc-deficient or a magnesium-deficient diet from the beginning of pregnancy and maternal bone marrow and fetal liver were removed on day 19 of gestation. Chromosome spreads were prepared and metaphases examined for abnormalities. Both magnesium- and zinc-deficient maternal bone-marrow and fetal liver cells showed significantly more chromosomal abnormalities than did those of controls. The chromosomal aberrations occurring in highest incidence in magnesium-deficient animals were terminal deletions and fragments. A higher than normal incidence of "stickiness" was also observed in cells from magnesium-deficient animals. In zinc-deficient animals, on the other hand, the chromosomal aberrations with the highest incidence were gaps and terminal deletions.     

Conformational changes of glyceraldehyde-3-phosphate dehydrogenase induced by the binding of NAD. A unified model for positive and negative cooperativity.

The fluorescence of the natural coenzyme, NADH, is used to monitor the environment of the nicotinamide moiety at the active centre of rabbit muscle glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12). Changes of the fluorescence quantum yield and polarization of a small amount of NADH, totally bound by an excess of enzyme, show that at half-saturation of the oligomer with NAD a conformational change is induced which affects the active centre regions of the remaining subunits. This conformational transition is not effected by adenosine diphosphoribose, suggesting that the binding of the nicotinamide moiety of NAD to two subunits is essential for the change of tertiary structure of the remaining subunits that causes the observed changes of the fluorescence properties of the ADH "tracer probe". It is suggested that this conformational transition of the oligomer is responsible for the major decrease of affinity for NAD which occurs at half-saturation, and possibly for the activation by NAD+ of the reductive dephosphorylation reaction catalysed by the enzyme. It is also suggested, by analogy with haemoglobin, that the molecular basis of the negative cooperativity may be the creation of additional intersubunit bonds during the binding of the first two NAD molecules to the tetramer, and a change from a "relaxed" quaternary structure to a "tense" structure at half-saturation.     

Oxygen uptake/heart rate relationship in leg and arm exercise, sitting and standing.

The effect of leg exercise and of arm exercise in sitting and standing body positions on energy output and on some cardiorespiratory parameters was studied in seven male subjects. Oxygen uptake (VO2), heart rate (fH), pulmonary ventilation (VE) and respiratory frequency were measured at rest, in the 7-8th min of submaximal work (300, 600, 900 kpm/min), and at maximal effort. Significantly higher Vo2, fH, and VE in arm cranking than in cycling were found at submaximal work loads above 300 kpm/min. Though the maximal work load in arm exercise was 50-60% of that in cycling, Vo2 in arm work was at maximal effort only 22% lower than in leg exercise while the difference in fH was insignificant. No differences were found in arm work between the results obtained at any work level in sitting and standing body positions. The only postural difference in arm work was a 13% higher work load achieved at maximal effort when standing than when sitting. Differences in fH between arm and leg exercise were much smaller for the same Vo2 than for the same work load and were time dependent. While fH quickly leveled off in leg exercise, fH in arm cranking rose steadily during the first 6 min of work which created the fH differences observed in the 7-8 min of submaximal arm arm and leg exercise. At submaximal work levels a tendency to synchronize the respiratory frequency with the frequency of the rotatory movements was more apparent in arm cranking than in cycling.     

Millipore filter assay for long-chain fatty acid:CoASH ligase activity using 3H-labeled coenzyme A.

A novel radiochemical assay for long-chain fatty acid:CoASH ligase activity (AMP) (EC 6.2.1.3) has been developed based on the conversion of [3H]CoASH to long-chain fatty acyl CoA. Fatty acyl [3H]CoA was quantitatively retained on Millipore filters upon filtration of the acidified reaction mixture under conditions where the [3H]CoASH was not retained. The assay was developed using microsomes derived from isolated fat cells as the source of fatty acid:CoASH ligase activity. The assay performed at 25 degrees C for 10 min was linear with added microsomal protein up to 7 mug. The assay was linear with time up to 24 min when 1 mug of protein was employed. Fatty acid:CoASH ligase activity was strongly dependent on ATP and magnesium, was stimulated by Triton WR-1339, and was two- to fivefold dependent on added fatty acid. The filter assay is easier than existing assays based on incorporation of labeled fatty acid and is equally sensitive.     

Reciprocal Recurrent Selection Compared to within-Strain Selection for Increasing Rate of Egg Lay of Tribolium under Optimal and Stress Conditions

A replicated comparison of reciprocal recurrent selection (rrs) based on crossbred performance and within strain-selection (wss) based on purebred performance was made in three diverse environments over ten generations for the improvement of a heterotic trait, 4-day virgin egg lay of Tribolium castaneum. A selection intensity of 20% based on performance in either an optimum (33°), a mild stress (38°), or a severe stress (28°) environment was applied uniformly. Periodically, the performance of each population was measured in all three environments to provide both direct and correlated responses.—Heritability of egg lay in the base population ranged from 0.36 ± 0.03 in optimum to 0.26 ± 0.03 in severe stress. Estimates of dominance effects assumed significant proportions in severe stress only. Genetic correlations for egg lay in diverse environments were large and positive (.6 to.8).—Only in severe stress did the rrs response significantly exceed that for wss. Quadratic adjustments fitted to response curves revealed that small initial genetic gains under rrs were followed by significantly increasing rates of gain in late generations of selection. The reverse was true for wss. This and evidence from realized heritabilities and genetic correlations suggested that rrs had utilized both additive and dominance effects, but wss response was limited to additive effects.—These results agree with selection theory in demonstrating that purebred selection is more efficient than crossbred selection in utilizing additive gene effects. The latter method has merit when non-additive effects assume significant proportions, and this is the more probable case for severe stress conditions.     

Multiple Transport Components for Putrescine in Escherichia coli

Putrescine uptake was studied in cultures of Escherichia coli K-12 grown in media of high or low osmolarity. When grown in high osmolarity medium, a transport system of low K(m) and low V(max) was found. For cultures grown in a medium of low osmolarity, the kinetics of putrescine uptake was more complex and consistent with the existence of an additional transport system of higher K(m) and V(max). This conclusion is supported by the isolation of mutants in which one or the other system appears to be defective and by the ability of chloramphenicol to block the expression of the second transport system. Both systems appear to prefer putrescine over other compounds, since several basic amino acids and other polyamines competed only weakly for transport. The action of both uptake systems was shown to cause significant displacement of intracellular putrescine. Both systems also are at least partially energy dependent.