PHENOTYPIC PLASTICITY IN THE SAILFIN MOLLY,POECILIA LATIPINNA (PISCES: POECILIIDAE). II. LABORATORY EXPERIMENT

Field studies indicate that the influence of environmental factors on growth rate and size and age at maturity in sailfin mollies (Poecilia latipinna) is inconsistent over time and suggest that the marked interdemic variation in male body size in this species is the result of genetic variation. However, the role of specific environmental factors in generating phenotypic variation must be studied under controlled conditions unattainable in nature. We raised newborn sailfin mollies from four populations in laboratory aquaria under all possible combinations of two temperatures, three salinities, and two food levels to examine explicitly the influence of these environmental factors. Males were much less susceptible than females to temperature variation and were generally less plastic than females in terms of all three traits. Members of both sexes matured at larger sizes and at later ages in less saline and in cooler environments. Food levels were not sufficiently different to affect the traits we studied. The effects of temperature and salinity were not synergistic. Males from different populations exhibited different average ages and sizes at maturity, but females did not. The magnitudes of the effects we found were not substantial enough to account for the consistent interdemic differences in male and female body size that have been observed previously. Our results also indicate that no single environmental factor is solely responsible for the environmental effects observed in field experiments on growth and development. These studies, together with other work, indicate that the strongest sources of interdemic variation are genetic differences in males and differences in postmaturation growth and survivorship in females.     

Ferrous Iron and Sulfur Oxidation and Ferric Iron Reduction Activities of Thiobacillus ferrooxidans Are Affected by Growth on Ferrous Iron, Sulfur, or a Sulfide Ore

Eight strains of Thiobacillus ferrooxidans (laboratory strains Tf-1 [= ATCC 13661] and Tf-2 [= ATCC 19859] and mine isolates SM-1, SM-2, SM-3, SM-4, SM-5, and SM-8) and three strains of Thiobacillus thiooxidans (laboratory strain Tt [= ATCC 8085] and mine isolates SM-6 and SM-7) were grown on ferrous iron (Fe²⁺), elemental sulfur (S⁰), or sulfide ore (Fe, Cu, and Zn). The cells were studied for their aerobic Fe²⁺ - and S⁰-oxidizing activities (O₂ consumption) and anaerobic S⁰-oxidizing activity with ferric iron (Fe³⁺) (Fe²⁺ formation). Fe²⁺-grown T. ferrooxidans cells oxidized S⁰ aerobically at a rate of 2 to 4% of the Fe²⁺ oxidation rate. The rate of anaerobic S⁰ oxidation with Fe³⁺ was equal to the aerobic oxidation rate in SM-1, SM-3, SM-4, and SM-5, but was only one-half or less that in Tf-1, Tf-2, SM-2, and SM-8. Transition from growth on Fe²⁺ to that on S⁰ produced cells with relatively undiminished Fe²⁺ oxidation activities and increased S⁰ oxidation (both aerobic and anaerobic) activities in Tf-2, SM-4, and SM-5, whereas it produced cells with dramatically reduced Fe²⁺ oxidation and anaerobic S⁰ oxidation activities in Tf-1, SM-1, SM-2, SM-3, and SM-8. Growth on ore 1 of metal-leaching Fe²⁺-grown strains and on ore 2 of all Fe²⁺-grown strains resulted in very high yields of cells with high Fe²⁺ and S⁰ oxidation (both aerobic and anaerobic) activities with similar ratios of various activities. Sulfur-grown Tf-2, SM-1, SM-4, SM-6, SM-7, and SM-8 cultures leached metals from ore 3, and Tf-2 and SM-4 cells recovered showed activity ratios similar to those of other ore-grown cells. It is concluded that all the T. ferrooxidans strains studied have the ability to produce cells with Fe²⁺ and S⁰ oxidation and Fe³⁺ reduction activities, but their levels are influenced by growth substrates and strain differences.     

Sudden large and periodic changes in heart rate in healthy young men after short periods of exercise.

The instantaneous heart rate and respiratory pattern were recorded immediately after brief periods of exercise in 41 healthy male students. Recordings were taken with the subjects both supine and standing. More than half of these subjects showed oscillatory heart changes when recovering supine but not when standing. During these oscillations the heart rate slowed suddenly by more than 30 beats/min; the oscillations had a period of 4 to 8 seconds, and they continued for half to two minutes. The P waves of the electrocardiogram were decreased during the slowing, consistent with increased vagal activity. When these oscillations occurred they each followed the start of an inspiration with the same latency as in respiratory sinus arrhythmia; unlike respiratory sinus arrhythmia, however, they did not occur after every inspiration but varied from 1:1 to 1:3 oscillations:breaths. They were not usually stopped by breath holding but were reduced or abolished by procedures which reduced venous return. This pattern of oscillations--"vagushalt"--seems to be different from respiratory sinus arrhythmias, and central venous pressure may contribute to the phenomenon. Although it is not widely recognised, vagushalt is probably very common and possibly its occurrence may change in disease.     

Enzymatic inactivation of human alpha-1-proteinase inhibitor by neutrophil myeloperoxidase.

Peanut agglutinin was acylated with a new heterobifunctional, cleavable photosensitive crosslinking reagent, N-[4-(p-azidophenylazo)benzoyl]-3-aminopropyl-N′-oxysuccinimide ester. The lectin derivative binds specifically and reversibly to neuraminidase-treated human erythrocyte ghosts and upon irradiation covalent attachment of over 35% of the bound lectin occurs. The affinity-crosslinked ghosts were solublized in deoxycholate, immunoprecipitated with anti-peanut agglutinin antiserum, and analyzed by sodium dodecylsulfate polyacrylamine gel electrophoresis. Bands containing both peanut agglutinin and membrane glycoproteins were detected with apparent molecular weights of 58 000, 85 000, 110 000 and 135 000. Upon subsequent cleavage with sodium dithionite, asialoglycophorin A (apparent M.W. 41 000 and 85 000) and a second glycoprotein (apparent M.W. 58 000 – 61 000) were tentatively identified as the receptors for peanut agglutinin in the intact membrane.     

Isolation of albumin from whole human plasma and fractionation of albumin-depleted plasma.

The dye Cibacron Blue F-3-GA was conjugated to Sepharose to provide an affinity column for serum albumin. Passage of whole human plasma through a column of Cibacron Blue-Sepharose results in the removal of approx. 98% of the albumin. The latter can be quantitatively recovered by desorption with NaSCN. Albumin-depleted plasma can be readily resolved into discrete fractions by a combination of conventional biochemical techniques. In particular, the resolution of plasma proteins with properties similar to those of native human plasma albumin can readily be accomplished by ion-exchange chromatography of the Sepharose-dye-treated plasma on DEAE-cellulose.     

Differential effects of oxidizing agents on human plasma alpha 1-proteinase inhibitor and human neutrophil myeloperoxidase

Human alpha 1-proteinase inhibitor is easily susceptible to inactivation because of the presence of a methionyl residue at its reactive site. Thus, oxidizing species derived from the myeloperoxidase system (enzyme, H2O2, and C1-), as well as hypochlorous acid, can inactivate this inhibitor, although H2O2 alone has no effect. Butylated hydroxytoluene, a radical scavenger, partially protects alpha 1-proteinase inhibitor from the myeloperoxidase system and completely protects it from hypochlorous acid. Each oxidant also reacts differently with the inhibitor, in that the myeloperoxidase system and hypochlorous acid can each oxidize as many as six methionyl residues, but hypochlorous acid can also oxidize a single tyrosine residue. Myeloperoxidase can be inactivated by hypochlorous acid, by autoxidation in the presence of H2O2 and C1-, as well as by H2O2 alone. Butylated hydroxytoluene completely protects this enzyme from hypochlorous acid inactivation, does not affect the action of H2O2, and enhances autoinactivation. As many as six methionyl residues and two tyrosine residues could be oxidized during autoxidation and six methionine residues by H2O2 alone. Eight methionine residues and one tyrosine residue could be oxidized by hypochlorous acid. The tyrosine residue in myeloperoxidase was oxidized only at a relatively high concentration (600 microM) of hypochlorous acid at which point the enzyme simultaneously and completely lost its enzymatic activity. Loss of activity of myeloperoxidase could also be correlated with the loss of the heme groups present in the enzyme when a relatively high concentration of hypochlorous acid (600 microM) was used and also during autoxidation. It appears that once there is sufficient oxidant to modify one of the tyrosine residues, the heme group itself becomes susceptible.     

Control of Redox Balance by the Stringent Response Regulatory Protein Promotes Antioxidant Defenses of Salmonella

We report herein a critical role for the stringent response regulatory DnaK suppressor protein (DksA) in the coordination of antioxidant defenses. DksA helps fine-tune the expression of glutathione biosynthetic genes and discrete steps in the pentose phosphate pathway and tricarboxylic acid cycle that are associated with the generation of reducing power. Control of NAD(P)H/NAD(P)⁺ redox balance by DksA fuels downstream antioxidant enzymatic systems in nutritionally starving Salmonella. Conditional expression of the glucose-6-phosphate dehydrogenase-encoding gene zwf, shown here to be under DksA control, increases both the NADPH pool and antioxidant defenses of dksA mutant Salmonella. The DksA-mediated coordination of redox balance boosts the antioxidant defenses of stationary phase bacteria. Not only does DksA increase resistance of Salmonella against hydrogen peroxide (H₂O₂), but it also promotes fitness of this intracellular pathogen when exposed to oxyradicals produced by the NADPH phagocyte oxidase in an acute model of infection. Given the role of DksA in the adjustment of gene expression in most bacteria undergoing nutritional deprivation, our findings raise the possibility that the control of central metabolic pathways by this regulatory protein maintains redox homeostasis essential for antioxidant defenses in phylogenetically diverse bacterial species.     

Structure and evolution of artiodactyla haptoglobins.

1. Artiodactyla haptoglobins (Hps), goat, sheep and cattle (family Bovidae), and pig (family Suidae) were structurally characterized. 2. The polymeric Hp systems of goat, sheep and cattle were similar to the polymeric human Hp system, while the monomeric system of pig was more comparable to the monomeric human form. 3. All members of the Artiodactyla (family Bovidae) examined exhibited a large polypeptide subunit, comparable to that of the beta subunit of human Hp. 4. In addition, a small subunit, similar in molecular weight to the human alpha 2 subunit, was demonstrated. Pig Hp was shown to have two subunits, one slightly larger than the human beta subunit and the other intermediate in size to the human alpha 1 and alpha 2 subunits. 5. Immunoelectrophoretic and immunodiffusion studies indicated complete cross reactivity among the polymeric Artiodactyla Hps. 6. The polymeric Hps do not, however, cross react with the monomeric pig Hp.