Antigenic subunit of the polypeptide antigenic complex of the Melvin strain of Neisseria gonorrhoeae.

An antigenic subunit of molecular weight 66,000 daltons has been isolated from the antigenic complex of the Melvin strain of $\text{Neisseria gonorrhoeae}$. Incubation of the complex in 8M urea at room temperature for four hours resulted in the dissociation of the subunit from the complex. It was separated from the complex by chromatography of the incubation mixture on a Sepharose 6B column in 50 mM ammonium bicarbonate pH 8.5 without 8M urea and further purified by affinity chromatography. This communication reports on a newly isolated antigenic protein devoid of LPS present in the bacteria.     

Disturbance of lymphocyte circulation byPseudomonas aeruginosa infection in oxazolone-sensitized mice

Pseudomonas aeruginosa infection depresses contact sensitivity to oxazolone in mice. To test whether an altered lymphocyte circulation plays a role in this depression⁵¹Cr-labeled lymphocytes fromP. aeruginosa-infected and oxazolone-sensitized donors were injected intravenously into infected and sensitized recipients, and the radioactivity uptake of several organs was determine. The controls consisted of normal mice receiving labeled lymphocytes from normal donors. While the radioactivity recovered from the liver, spleen, and mesenteric lymph nodes was similar in the test and the control group, significantly more radioactivity was recovered from the draining lymph nodes of infected and sensitized recipients. The concentration of labeled lymphocytes from sensitized donors in the draining lymph nodes of sensitized recipients was 18% greater than that of the controls but 31% lower than that of infected and sensitized animals receiving cells from infected and sensitized donors.P. aeruginosa infection enhances lymphocyte entrapment within the draining lymph nodes of oxazolone-sensitized mice.     

NADH: Nitrate reductase activity restoration by rhodanese

The NADH: nitrate reductase from durum wheat leaves was inactivated by cyanide and its activity restored by thiosulphate and beef kidney rhodanese. Rhodanese and thiosulphate, added to NADH-nitrate reductase before cyanide treatment protected NADH-nitrate reductase activity. No oxidizing agent was required for the protection or restoration of cyanide treated NADH-nitrate reductase.     

Effect of different carbon sources on the biosynthesis of polyunsaturated fatty acids ofα-linolenic acid family in culture of minimal deviation hepatoma 7288 c cells

Summary The effect of three different carbon sources on the biosynthesis of polyunsaturated fatty acids of the-linolenic acid series was investigated in hepatoma tissue culture (HTC) cells. Alpha linolenic acid was converted to higher homologs by a desaturating route that synthetized mainly 18:4 (6, 9, 12, 15), 20:4 (8, 11, 14, 17) and 20:5 (5, 8, 11, 14, 17) and an elongating route that produced 20:3 (11, 14, 17) and 20:4 (5, 11, 14, 17) acids. Fasting decreased both biosynthetic routes whereas glucose reactivated only the elongating pathway. Lactalbumin hydrolysate enhanced significantly only the desaturating route whereas glycerol was inactive. Glucose and aminoacids increased similarly the incorporation of labeled linolenic acid in the cells. The results are independent of hormonal effects.Members of the Carrera del Investigador Científico of the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.     

Experimental allergic aspermatogenic orchitis. II. Some chemical properties of the AP1 protein of the sperm acrosome.

The AP1 protein, a unique aspermatogenic protein localized in the sperm acrosome, exists as a single polypeptide chain of 136 amino acids, as shown by a single band on gel electrophoresis in sodium dodecyl sulfate and the recovery of the expected 21 to 22 tryptic peptides on peptide mapping. The AP1 protein appears to exist in a compact, highly stable conformation, as shown by its resistance to trypsin hydrolysis. Its aspermatogenic acitivity is not affected by trypsin treatment, by heating at 99 degrees C for 1 h, by 8 M urea, or by acid conditions. After reduction and alkylation, however, the molecule appears to open up, since it becomes hydrolyzable by trypsin and migrates more slowly on gel electrophoresis at pH 2.7 and 8.6. After alkylation, the AP1 protein still migrates as a single band at pH 2.7. The AP1 protein shows microheterogeneity near its isolectric point at pH 8.6; each of five bands shows the same amino acid analysis. Aggregation was not observed following treatment with dimethylsuberimidate. The molecular weight of 15 000, obtained from gel electrophoresis consists of 136 amino acids with a relatively high content of proline, half cystine, glycine, histidine and tryptophan. No galactose, mannose, fucose, glucose, or hexosamines were found; the AP1 protein is thus not a glycoprotein.     

Dexamethasone effects on liver pyruvate kinase

Dexamethasone in the medium perfusin isolated rabbit livers caused a fast-acting and reversible effect on liver pyruvate kinase. The effect was to lower th assayable V activity (units/g tissue) without changing the concentration (nmol/g enzyme protein). In effect, glucocorticoid lowered the specific activity (units/nmol of enzyme) by direct action on liver. The effect on liver pyruvate kinase is mediated by a relatively stable alteration; 30 min after perfusate (with steroid) was replaced by perfusate (without steroid), the effect remained strongly evident.