Murine mammary tumor virus structural protein interactions: formation of oligomeric complexes with cleavable cross-linking agents

Murine mammary tumor virus protein interactions in the intact virion structure were studied with the use of the cleavable cross-linking reagents dithiobis(succinimidyl propionate) and methyl 4-mercaptobutyrimidate hydrochloride. Cross-linked oligomeric complexes of murine mammary tumor virus proteins were analyzed by two-dimensional gel electrophoresis. Among the complexes most consistently formed were a heterodimer of the two glycoproteins gp36 and gp52, the homodimer of gp36, and the homotrimer of gp52. A very prominent oligomer formed at higher concentrations of dithiobis(succinimidyl propionate) was a complex of about 230,000 molecular weight, made up of three molecules each of gp36 and gp52. A number of lines of evidence, including electron microscopic analysis, suggest that the 230,000-molecular-weight complex actually represents the murine mammary tumor virus spike structure. Of the murine mammary tumor virus core proteins, p14 forms homooligomers most readily. Upon cross-linking with methyl 4-mercaptobutyrimidate hydrochloride a small amount of what seems to be a heterodimer made up of the N-terminal gag protein p10 and the hydrophobic membrane glycoprotein gp36 can be observed.     

Selective resistance of bacterial polyadenylate-containing RNA to hydrolysis by guanosine 3'-5'-monophosphate-sensitive nuclease of Bacillus brevis

Earlier experiments had shown that the degradation of newly synthesized RNA in permeable cells of Bacillus brevis is mediated primarily by a guanosine 3′,5′-monophosphate-sensitive 3′-exonuclease [N. Sarkar and H. Paulus (1975) J. Biol. Chem. 250, 684–690]. More recently, we found that a substantial fraction of pulse-labeled RNA in B. brevis is polyadenylylated [N. Sarkar, D. Langley, and H. Paulus (1978) Biochemistry 17, 3468–3474], and it was thus of interest to examine the effect of polyadenylylation on the susceptibility of RNA to degradation by the 3′-exonuclease. Purified 3′-exonuclease from B. brevis hydrolyzed the unadenylylated fraction of pulse-labeled RNA from B. brevis much more rapidly than poly(A)-containing RNA. Similar results were obtained with the pulse-labeled unadenylylated and polyadenylylated RNA fractions from Bacillus subtilis. Control experiments showed that the differential hydrolysis of the labeled RNA preparations by 3′-exonuclease was not due to the presence of inhibitors or activators. These results suggest that the stability of mRNA in Bacillus species may be regulated by polyadenylylation.     

Purification of murine oncornaviral phosphoproteins using alkyl agarose derivatives..

Methods for the purification of both murine mammary tumor (type B) and murine leukemia (type C) oncornaviral phosphoproteins are described, in which chromatography on alkyl-agarose derivatives is used as the primary fractionation step. Gel filtration or ion exchange chromatography on phosphocellulose was the only subsequent step required for the purification of the type B and type C viral proteins, respectively. The two-step protocols also resulted in the co-purification of a low molecular weight core protein from each virus. Recoveries of the viral proteins purified by this method, based on per cent contribution of individual polypeptides to total virion proteins, were 70% or greater. Radioimmunocompetition analysis of the purified murine mammary tumor virus major core protein as well as analysis of the RNA binding properties of purified low molecular weight type C virus proteins suggests that neither antigenic reactivity nor specific RNA binding characteristics are altered by the purification protocols. The availability of these procedures should aid studies on the possible function and immunochemical properties of the native murine oncornaviral phosphoproteins and may also be extended to the purification of other oncornaviral proteins.     

A new non-steroidal drug for long-acting contraception.

A new contraceptive compound had been prepared with the common ingredients and it was applied in female rats. The efficacy and toxicity tests of this compound showed that this drug has along-acting contraceptive value not causing any side-effects.     

Equilibrium studies of zinc(II) and cobalt(II) binding to tripeptide analogues of the amino terminus of human serum albumin

Serum albumin is known to bind several divalent metal ions at the amino terminus of the protein. Two peptide analogues for the amino terminus of human albumin, L-aspartyl-L-alanyl-L-histidine-N-Methyl amide (AAHNMA) and glycylglycyl-L-histidine-N-methyl amide (GGHNMA) have been synthesized, and their interactions with Zn(II) and Co(II) ions have been studied using analytical potentiometry. The stability constants of the species and their distribution as a function of pH were determined in 0.16-M KNO₃ at 25°. Comparison of the modes of interaction of the Zn(II) and Co(II) with each of the above peptides indicate that, although Co(II) is a valuable tool for the study of Zn(II) interaction with metalloenzymes, it is considerably less useful as a Zn(II) model with small peptide molecules. The potentiometric properties of the two peptide-Zn(II) systems have been compared to the potentiostatic properties of the albumin-Zn(II) system. The results indicate that AAHNMA is a better analogue for the Zn(II)-HSA interaction than is GGHNMA. The findings suggest that the Zn(II)-HSA binding site is best described as a compound site containing both a histidyl and a neighboring carboxyl group.     

Effect of metals on the regulation of acidogenic metabolism enhancing biohydrogen and carboxylic acids production from brewery spent grains: Microbial dynamics and biochemical analysis

The present study reports the mixed culture acidogenic production of biohydrogen and carboxylic acids (CA) from brewery spent grains (BSG) in the presence of high concentrations of cobalt, iron, nickel, and zinc. The metals enhanced biohydrogen output by 2.39 times along with CA biosynthesis by 1.73 times. Cobalt and iron promoted the acetate and butyrate pathways, leading to the accumulation of 5.14 gCOD/L of acetic and 11.36 gCOD/L of butyric acid. The production of solvents (ethanol + butanol) was higher with zinc (4.68 gCOD/L) and cobalt (4.45 gCOD/L). A combination of all four metals further enhanced CA accumulation to 42.98 gCOD/L, thus surpassing the benefits accrued from supplementation with individual metals. Additionally, 0.36 and 0.31 mol green ammonium were obtained from protein‐rich brewery spent grain upon supplementation with iron and cobalt, respectively. Metagenomic analysis revealed the high relative abundance of Firmicutes (>90%), of which 85.02% were Clostridium, in mixed metal‐containing reactors. Finally, a significant correlation of dehydrogenase activity with CA and biohydrogen evolution was observed upon metal addition.     

Seasonal distribution of Vibrio parahaemolyticus in freshwater environs and in association with freshwater fishes in Calcutta

The seasonal distribution of Vibrio parahaemolyticus in freshwater environs and in association with freshwater fishes was studied in 1982 and 1983. The occurrence of this organism in water and sediments at the three sites studied was very infrequent and was restricted to the summer months, although it was not always isolated during these months. The association of V. parahaemolyticus with plankton was chiefly confined to the summer months and progressively declined with the onset of monsoons, remaining below detectable levels during the postmonsoon and winter months. The incidence and counts of V. parahaemolyticus were consistently higher in association with plankton than with water and sediment samples. V. parahaemolyticus could be recovered throughout the period of investigation from freshly caught and market samples of freshwater fishes. The highest recovery rate of this halophile from fishes was invariably from fecal samples. Most of the strains isolated in this study were untypable, and those which could be typed were predominantly serotypes encountered in the environment. All the isolates were Kanagawa negative. From this study, it could be concluded that the survival of V. parahaemolyticus in freshwater ecosystems is transient and dependent on a biological host.