Changes in the levels of pituitary and steroid hormones in ovine and human ovarian follicular fluid

Changes in the protein and steroid hormones of follicular fluid, aspirated from different follicles of sheep and human ovaries, have been measured and correlated with the size of the follicles. As the fluid contains a number of proteins, steroids have been measured directly and after ether extraction. The follicular fluid concentrations of progesterone and 17 beta-oestradiol measured directly in the fluid increased with the size of the follicles. The levels of free testosterone remained constant in all sizes of follicles, while those of bound hormone showed a 10- to 15-fold increase over the free testosterone concentrations in both the sheep and human follicular fluid. A decrease in the levels of bound testosterone in the fluid of large follicles (LFFL) coincided with the increase in bound 17 beta-oestradiol, suggesting the possible conversion of bound testosterone to oestrogen as the follicle attained maturity. The ratio of follicle-stimulating hormone (FSH) to luteinizing hormone (LH) varied in the fluid obtained from different size follicles, being 1:7 in small (SFFL), 1.3.5 in medium (MFFL) and 1:2.3 in large (LFFL) follicles of sheep ovaries. The LH content of follicular fluid of different size follicles appeared to be the same, with LFFL showing a minor increase over SFFL. In the human, the fluid from medium follicles contained very little LH compared to LFFL. These differences in the pattern of LH levels present in the fluid from different size follicles between human and sheep ovaries presumably reflect species variations in the entry of LH into the follicles.     

Immobilization of amyloglucosidase on polystyrene anion exchangeresin II. Kinetics and stabilities

Summary Amyloglucosidase (exo-1, 4- -D-glucosidase, EC 3.2.1.3), was coupled to glutaraldehyde activated Indion 48-R (a cross-linked macroporous anion exchanger) by Schiff base reaction. Immobilization brought about a marginal increase in the apparent K_m. The bound enzyme exhibited increased stability towards urea and metal ions, but was less stable in the presence of guanidine hydrochloride. Immobilized amyloglucosidase could be stored at 4°C (in wet state) for 6–8 months without any apparent loss of activity.     

Catechol Formation and Melanization by Na+ -Dependent Azotobacter chroococcum: a Protective Mechanism for Aeroadaptation?

Aeroadaptive microaerophilic Azotobacter chroococcum 184 produced a cell-associated black pigment when grown at high aeration rates under nitrogen-fixing conditions. This pigment was shown to be a catechol melanin. Polyphenol oxidase activity was detected in cell extracts of cells grown for 72 h. Melanin formation was optimal in the later stages of growth, and there was no correlation between nitrogenase activity and melanization. Nitrogenase activity in strain 184 was optimal at 10% O₂, and melanin formation was suppressed by O₂ limitation. In the presence of charcoal, an adsorbent of toxic oxygen intermediates, and benzoic acid, a scavenger of hydroxyl radicals, melanization was inhibited. However, in the presence of copper, the intensity of pigment color increased and melanization was accelerated. Copper also eliminated catalase and peroxidase activities of the organism but still permitted aerobic growth. In the presence of low levels of iron, melanization was accelerated under high aeration rates, and under low rates of aeration, melanization was observed only at higher levels of iron. Hydroxamate-siderophore production was detectable in the presence of soluble iron under high rates of aeration but was repressed by the same levels of iron under low aeration rates. Unlike melanization and hydroxamate formation, catechol formation was observed under both low and high rates of aeration under nitrogen-fixing conditions. Catechol formation and melanization were repressed by 14 mM NH₄⁺, at which level nitrogenase activity was also repressed. Copper reversed the repressive effect of NH₄⁺. A role for catechol formation and melanization in aeroadaptation is proposed.     

Glucagon and p21 ras enhance the phosphorylation of the same 38-kilodalton membrane protein from rat liver cells.

We had reported earlier the enhanced phosphorylation of a 38-kilodalton protein (p38) in rat liver plasma membrane by ras proteins. Now we show that glucagon increased the phosphorylation of the same protein. The nature and site(s) of phosphorylation were the same as those for the ras proteins. Both ATP and GTP could donate phosphate for the phosphorylation of p38. The stimulation of p38 phosphorylation by glucagon was guanine nucleotide dependent. This observation, together with our data on the stimulation of p38 phosphorylation by AIF4-, suggest the involvement of G proteins in the reaction. We also showed that glucagon stimulates the phosphorylation of p38 in vivo.     

Sleep patterns at an altitude of 3500 metres

Alterations in sleep pattern during acclimatisation at an altitude of 3500 m were studied on 27 healthy men (20–30 years of age). Of these, 15 were sojourners (SJ), 6 were acclimatised lowlanders (AL) and 6 were high altitude natives (HAN). Baseline sleep profile of SJ was electrophysiologically monitored, initially at Delhi (260 m) and later at 3500 m altitude in Western Himalayas for 2 weeks. At high altitude (HA) the sleep patterns of AL and HAN were also monitored for comparison. There were 4 cases of acute mountain sickness (AMS) among SJ, whose sleep profiles were also recorded. The state of autonomic arousal was assessed by a battery of indices, while the psychological arousal was measured by the anxiety scales. On completion of studies at HA, the SJ were flown back to the plains and re-tested within one week of return. SJ showed curtailment of slow wave sleep (SWS) and frequent short episodes of arousal during sleep at HA. AL and HAN also had lesser amounts of SWS; however, the arousals and awakenings during sleep were less frequent. Subjects who experienced AMS had normal amounts of SWS at HA. There was sympathetic hyperactivity and slight increase in anxiety level in SJ, while HAN and AL had relatively reduced level of sympathetic activity. The curtailment of SWS and frequent arousals observed in SJ during the initial phase of acclimatisation at HA, appear to be adaptive features to prevent the accentuation of arterial hypoxemia due to sleep hypoventilation.     

Identification and physical characterization of yeast maltase structural genes

Summary Each of at least five unlinked MAL loci (MAL1 through MAL4 and MAL6) on the yeast genome controls the ability to synthesize an inducible -D-glucosidase (maltase). A subcloned fragment of the coding sequence of the MAL6 maltase structural gene was used as a hybridization probe to investigate the physical structure of the family of MAL structural genes in the genomes of different Saccharomyces strains. Mal⁺ strains, each carrying a genetically defined MAL locus, were crossed with a Mal^- strain and the segregation behavior of the functional locus and of sequences complementary to the maltase structural gene at that locus analyzed. The maltase structural gene sequences of each MAL locus were detected by Southern blot hybridization using BamH1 digests of genomic DNA of the meiotic products. This restriction enzyme was previously shown to cleave outside the confines of the MAL6 locus.The results of such experiments indicate that each MAL locus encompasses at least one maltase structural gene sequence homologous to that of MAL6, that yeast strains that lack functional MAL loci may or may not contain the corresponding maltase structural gene sequence, that the MAL1 maltase structural gene sequence or one of its alleles can be detected in all laboratory yeast strains examined and that each MAL locus can be identified as a characteristic BamH1 fragment of genomic DNA which includes a maltase structural gene.Yeast strains vary in the number of maltase structural gene sequences that they carry. By using the approach described in this report, the ones corresponding to the different functional MAL loci and residing within a BamH1 generated restriction fragment can be identified.     

recO and recR mutations delay induction of the SOS response in Escherichia coli

RecF, RecO and RecR, three of the important proteins of the RecF pathway of recombination, are also needed for repair of DNA damage due to UV irradiation. recF mutants are not proficient in cleaving LexA repressor in vivo following DNA damage; therefore they show a delay of induction of the SOS response. In this communication, by measuring the in vivo levels of LexA repressor using anti-LexA antibodies, we show that recO and recR mutant strains are also not proficient in LexA cleavage reactions. In addition, we show that recO and recR mutations delay induction of -galactosidase activity expressed from a lexA-regulated promoter following exposure of cells to UV, thus further supporting the idea that recF, recO and recR gene products are needed for induction of the SOS response.     

Signal sequence insufficiency contributes to neurodegeneration caused by transmembrane prion protein

Protein translocation into the endoplasmic reticulum is mediated by signal sequences that vary widely in primary structure. In vitro studies suggest that such signal sequence variations may correspond to subtly different functional properties. Whether comparable functional differences exist in vivo and are of sufficient magnitude to impact organism physiology is unknown. Here, we investigate this issue by analyzing in transgenic mice the impact of signal sequence efficiency for mammalian prion protein (PrP). We find that replacement of the average efficiency signal sequence of PrP with more efficient signals rescues mice from neurodegeneration caused by otherwise pathogenic PrP mutants in a downstream hydrophobic domain (HD). This effect is explained by the demonstration that efficient signal sequence function precludes generation of a cytosolically exposed, disease-causing transmembrane form of PrP mediated by the HD mutants. Thus, signal sequences are functionally nonequivalent in vivo, with intrinsic inefficiency of the native PrP signal being required for pathogenesis of a subset of disease-causing PrP mutations.