Study of relationship among species ofVibrio,Photobacterium, and terrestrial enterobacteria by an immunological comparison of glutamine synthetase and superoxide dismutase

The amino acid sequence divergence of glutamine synthetase (GS) from species ofVibrio, Photobacterium, Aeromonas, Escherichia, Salmonella, Citrobacter, Enterobacter, Serratia, Proteus, Erwinia, Xenorhabdus, andPlesiomonas was determined by quantitative microcomplement fixation, using antisera to GS fromVibrio alginolyticus andEscherichia coli. A similar study was performed with superoxide dismutase (SOD), using antiserum to the enzyme fromV. alginolyticus. A comparison of the results for GS and SOD, relative to the enzymes fromV. alginolyticus, as well as a comparison of these data with the results of previous ribosomal RNA (rRNA)/DNA homology studies indicated a high degree of congruence (correlation coefficients≥0.9). The results with both enzymes suggested four major groupings among these genera: (i)Vibrio, (ii)Photobacterium, (iii)Aeromonas, (iv) a large and heterogeneous group which included the peritrichously flagellated terrestrial enterobacteria.     

A review of some physiological and toxicological responses of freshwater fish to acid stress

Synopsis Data relating to the specific effect of low pH on growth of freshwater fishes are ambiguous. Reproductive failure resulting from acid stress appears to be related to an upset in calcium metabolism and to faulty deposition of protein in developing oocytes. It appears that the ’no effect‘ level of pH depression for successful reproduction is around 6.5. Data on behaviorial responses of freshwater fish to acid stress and CO₂ are described. Most fish appear to be indifferent to pH within the range of approximately 10.5 to 5.5 and between 7.4 and 4.5 CO₂ appears to be the main directive factor. In cases of severe acid stress alteration of gill membranes and/or coagulation of gill mucus occurs and death due to hypoxia may result from a lengthening of the water-blood diffusion distance. Several reports agree that acid stress causes an upset of electrolyte homeostasis in fish but effects of low pH on osmotic permeability are largely lacking. Most hatcheryreared salmonids can tolerate pH 5.0 indefinitely but below this level the homeostatic electrolyte and osmotic regulatory mechanisms become inadequate. When fish are subjected to debilitating acid stress blood pH decreases possibly as the result of flux of H⁺ ions across gill membranes into the blood. This could change transepithelial potential and allow a blood, to-water diffusion of Na⁺ ions down an electrochemical gradient. Lowered ambient pH may interfere with gill calcium levels increasing permeability to both H⁺ and Na⁺ ions or an acidemia may occur as the result of a decrease in the excretion of metabolically produced H⁺ ions and CO₂. When the capacity of the buffer mechanisms is exceeded the blood pH drops and the capacity of hemoglobin to transport oxygen is decreased.     

Investigations into the potential for embryo transfer from Brucellaabortus infected cows without transmission of infection

Thirty-six attempts were made to isolate $\text{Brucella}$$\text{abortus}$ from the uterine flushings of culture positive and serologic reactor cows. Sixteen of these attempts were made after cows had been programmed for superovulation and a simultaneous attempt was made to recover eggs. Udder secretion samples for culture and blood for serology were collected at the time of the flushing procedure. In addition, a field isolate of $\text{Brucella}$$\text{abortus}$ suspended in three different solutions (one commonly used for nonsurgical embryo retrieval) was quantitated at various intervals up to 24 hours.Brucellae were not cultured from any of the uterine flushings although it was demonstrated that the organisms would remain viable in the media used for up to 24 hours. Udder secretions contained brucella at the time of flushing in 17 of the 36 attempts. Results indicated that transfer from infected donors might be achieved without transfer of infection. It is cautioned that final evidence of success would have to come after recipients had undergone serologic and cultural surveillance through their gestation period.     

Glucose production using immobilized mycelial-associated β-glucosidase of Trichoderma E58

Summary The immobilization of the mycelial-associated -glucosidase of Trichoderma E-58 has been carried out by encapsulating, in calcium alginate beads, the fungal mycelium obtained durinq liquid culture. The activity of this immobilized -glucosidase was found to vary with culture age and to be more thermally stable than the extracellular -glucosidase produced by this organism. The activity of the immobilized enzyme was successfully demonstrated in both static and shake-flask batch reaction mixtures at 50°C using both cellobiose and salicin as substrates.     

Effects of hydroxylamine and silicomolybdate on the decay in delayed light emission in the 6–100 μs range after a single 10 ns flash in pea thylakoids

Measurements are reported on μs delayed light emission, following a single 10 ns excitation flash, in Alaska pea thylakoids treated with hydroxylamine (NH₂OH) or with silicomolybdate.

1. In thylakoids treated with 2 mM NH₂OH in the light, or in the dark, the quantum yield of delayed light emission is considerably enhanced. A 10 μs lifetime component of delayed light emission is not significantly changed, whereas a 50–70 μs lifetime component is increased. MnCl₂ and diphenylcarbazide are unable to reverse the above effects of NH₂OH treatment. Thus Mn²⁺ and diphenylcarbazide must not donate electrons directly to reaction center II but on the oxygen-evolution side of the NH₂OH block.
2. When the closed form of photosystem II reaction centers (P₆₈₀Q^-), where P₆₈₀ is the reaction center chlorophyll and Q is a ‘stable’ electron acceptor, is generated by preillumination of NH₂OH-treated thylakoids with diuron present, the μs delayed light emission is inhibited, but a low level residual delayed light emission remains. Possible origins of this emission are discussed. It is believed that the best explanation for residual DLE is the existence of another acceptor besides Q that partakes in charge separation and rapid dissipative recombination when the reaction center is in the P₆₈₀Q^- state.
3. The quantum yield of delayed light emission from ‘closed’ reaction centers (P₆₈₀ ⁺Q^-) that have all charge stabilization reactions (i.e., flow of electrons to P₆₈₀ ⁺ and out of Q^-) blocked by NH₂OH treatment and addition of diuron is 1.1×10^-3 for components measured in a range from 6 to 400 μs and extrapolated to zero time.
4. The addition of silicomolybdate, which accepts electron from Q^-, causes delayed light emission in the μs range to be greatly inhibited.

     

The fluidity of the nuclear envelope lipid does not affect the rate of nucleocytoplasmic RNA transport in mammalian liver

The effects of in vitro and in vivo modifications of nuclear envelope lipid on DNA leakage and on ATP-stimulated RNA release from isolated rat liver nuclei were investigated. The modifications included corn-oil feeding of the animals to alter the fatty acid composition of the lipids, phospholipase treatment of the isolated nuclei, and extraction of the total lipid with Triton X-100. Significant changes in lipid composition and approximate order parameter values of the spin-label 5-doxylstearate resulted, but there was no significant effect on RNA transport rate. It was concluded that the nuclear envelope lipid does not play any important part in nucleocytoplasmic RNA transport in mammalian liver.     

Evidence that the hepatic asialoglycoprotein receptor is internalized during endocytosis and that receptor recycling can be uncoupled from endocytosis at low temperature

Rat hepatocytes in the continuous presence of [³H]asialo-orosomucoid quickly establish a steady state number of free and occupied surface receptors and rate of endocytosis. These values do not change even though many times more glycoprotein is internalized than there are surface receptors per cell. However, when cells endocytose only one round of surface bound [³H]asialo-orosomucoid at 37°C the internalization of glycoprotein is about 5 times faster than the increase of functional receptors on the cell surface. At 18°C new surface receptors appear at only 6% of the rate of internalization of pre-bound asialoglycoprotein. The results suggest that reutilization of asialoglycoprotein receptors is preferentially inhibited at low temperature and that receptor-ligand complexes enter the cell.     

Synthesis of two forms of apolipoprotein B by cultured rat hepatocytes

Cultured rat hepatocytes were used to demonstrate that the liver can synthesize two forms of apolipoprotein B. Separation of apolipoprotein B by disc gel electrophoresis indicated that hepatocyte low density lipoprotein contains predominantly apolipoprotein B with an apparent molecular weight of 345,000 ± 5,055. In contrast, the major apolipoprotein B component of hepatocyte very low density lipoprotein is a variant form with a molecular weight of 242,000 ± 2,720. Hepatocyte high density lipoprotein, unlike plasma HDL, also contains apolipoprotein B with an apparent molecular weight of 244,000 ± 2,742. Incorporation of [³H] leucine into hepatocyte apolipoprotein B components suggested de novo synthesis.     

1,25-Dihydroxyvitamin D3 increases serum levels of the vitamin K-dependent bone protein

1,25-dihydroxyvitamin D₃ increases serum levels of bone Gla protein (BGP). The maximal increase occurs 12 h after injection and is given by 350 ng 1,25(OH)₂D₃ per 180 g body weight. In both 2 and 11 month-old male rats, the maximal increase is about 3 times the normal level, while in 2 month old female rats, the maximal increase is 2 times the normal level. These effects of 1,25(OH)₂D₃ in rats parallel the previously described effects of the vitamin on BGP secretion by rat osteosarcoma cells in culture.BGP is the first bone-specific protein whose synthesis in animals is dramatically increased by 1,25(OH)₂D₃. The possible functions of BGP in the biological actions of 1,25(OH)₂D₃ on bone are discussed.