Detection of gonadotrophic hormones on isolated granulosa cells of the domestic hen, Gallus domesticus, by an immunohistochemical method

Two immunohistochemical methods were used to detect the presence of luteinizing hormone (LH) on the cells of chicken granulosa. Using a peroxidase-labelled anti-rabbit serum together with anti-chicken LH serum raised in rabbits, a strong positive response was obtained with granulosa cells from small and large pre-ovulatory follicles obtained from the mid-cycle. Similarly, by using an available antiserum to human follicle stimulating hormone (FSH), a slightly weaker response was obtained with cells from both large and small follicles. After incubating cells with ovine LH, ovine FSH and ovine prolactin, there was no detectable difference with the method used in reaction with their respective antisera to cells which had received no incubation, implying that chicken gonadotrophins were displaced only partially from their receptors by mammalian gonadotrophic hormones. Pre-incubation of the cells with human chorionic gonadotrophin gave negative results with anti-hCG serum. Using a fluorescent-labelled antibody method, similar results were obtained except that the distribution of the receptors on the granulosa cell for LH or FSH appeared to be different. With the LH, the fluorescence formed a halo around the cell in contrast to the overall fluorescence with FSH.     

Environmental cadmium is not sequestered by metallothionein in rainbow trout

Smooth endoplasmic reticulum vesicles from rat liver display an ATP-supported Ca²⁺ transport which is mediated by a (Ca²⁺ + Mg²⁺)-ATPase. During the catalytic cycle the terminal phosphate from ATP is incorporated to form an acid-precipitable reaction product(118 000-M_r in SDS-gel electrophoresis) with stability characteristics of an acylphosphate. Comparative studies with sarcoplasmic reticulum vesicles from fast-twitch skeletal muscle suggest that the 118 000-M_r phosphopeptide may be identified with the phosphorylated reaction intermediate of a Ca²⁺ transport ATPase in endoplasmic reticulum, similar to that in sarcoplasmic reticulum of muscle.     

Immunosuppression as a high-risk factor in the development of condyloma acuminatum and squamous neoplasia of the cervix

The iatrogenic immunosuppression in renal transplant recipients has been associated with an increased incidence of malignancy in these patients. Among 132 female transplant recipients at risk for the development of squamous lesions of the cervix, 11 (8.5%) developed cervical condylomas. Six (4.5%) of the 11 patients developed cervical neoplasia. The average age of the patients at the time of initial diagnosis was 32.2 years. The lag time from transplantation to the diagnosis of the condyloma was 22.4 months, and the lag time from transplantation to the diagnosis of cervical neoplasia was 38.0 months. The increased incidence of condylomas as well as of intraepithelial neoplasia of the cervix in this group of patients with an established higher risk of malignancy supports the hypothesis that condylomas may represent a precursor lesion of cervical cancer. Immunosuppression should be included among the high-risk factors in the development of cervical neoplasia.     

True grit: A microwear experiment

Recently we noted the effects of experimental diets on microscopic dental wear in the American opossum and concluded that it might prove difficult to distinguish the microwear produced by an insectivorous diet from that produced by some kinds of herbivorous ones. We also noted that wear caused by gritty diets and those containing plant opal, although they might be confused with one another, are easily distinguished from other sorts of dietary wear. Our conclusions have been challenged on the basis that possibly we did not allow sufficient time in the experiments for diagnostic wear patterns to emerge. Additional data reported here show that this is not so. Even in our n “control” animals, fed a relatively soft unabrasive diet, enough time elapsed to produce significant dental wear. A new technique is described which for the first time allows the study of changing patterns of microscopic wear in a living animal over a period of time, thus allowing each animal to serve as its own control. A solution containing a broad-spectrum proteolytic enzyme when applied to the teeth of an anesthetized animal removes the proteinaceous coat (pellicle) which will otherwise obscure wear scratches. Precision dental impressions can then be made which reveal the details of the pattern of microwear on the teeth.     

Catalase and superoxide dismutase in Escherichia coli

We assessed the roles of intrabacterial catalase and superoxide dismutase in the resistance of Escherichia coli to killing by neutrophils. E. coli in which the synthesis of superoxide dismutase and catalase were induced by paraquat 10-fold and 5-fold, respectively, did not resist killing by neutrophils. When bacteria were allowed to recover from the toxicity of paraquat for 1 h on ice and for 30 min at 37 degrees C, they still failed to resist killing by neutrophils. Induction of the synthesis of catalase 9-fold by growth in the presence of phenazine methosulfate did not render E. coli resistant to killing by either neutrophils or by H2O2 itself. The lack of protection by intrabacterial catalase from killing by neutrophils could not be attributed to an impermeable bacterial membrane; the evolution of O2 from H2O2 was no less rapid in suspensions of E. coli than in lysates. The failure of intrabacterial catalase or superoxide dismutase to protect bacteria from killing by neutrophils might indicate either that the flux of O-2 and H2O2 in the phagosome is too great for the intrabacterial enzymes to alter or that the site of injury is at the bacterial surface.     

Antimicrobial activity and physico-chemical properties of some alkyldimethylbenzylammonium chlorides

A series of alkyldimethylbenzylammonium chlorides have been synthesized with n-alkyl chain lengths of C1 leads to C18. Octanol/water partition coefficients were determined and the antimicrobial activity assessed as the minimum growth inhibitory concentrations towards twelve strains of micro-organisms, representative of Gram-negative and Gram-positive bacteria, yeasts and fungi. The data were subjected to a numerical analysis. Antimicrobial activity of the compounds was found to be a parabolic function of their lipophilicity and maximized with n-alkyl chain lengths of between C12 and C16. The data fit to quadratic functions estimated for low (C1-C7) and high (C8-C16) alkyl chain length compounds was better than for a single quadratic describing the activity of the complete series (C1-C18). These maximized at log P values corresponding to alkyl-chain lengths of approximately C7 and C14 respectively, and were suggestive of low and high affinity binding sites upon the cell surface. The data analysis allowed the chain lengths of compounds with optimal activity towards the various groups of organisms to be determined. Generally yeasts and fungi were most sensitive towards C12, Gram-positive bacteria towards C14, and the Gram-negative bacteria towards C16. Gram-negative cells were the most resistant towards all the compounds and Gram-positive cells the least.     

Dictyostelium mutants lacking DIF,a putative morphogen

DIF is an endogenous extracellular signal that may control differentiation of D. discoideum cells. It is a dialyzable, lipid-like factor that induces stalk cell formation among isolated amebae incubated in vitro with cAMP. To examine the consequences of DIF deprivation, we have isolated several mutant strains that are impaired in DIF accumulation, and whose inability to make stalk cells in vitro and during normal development on agar can be corrected by the addition of exogenous DIF. Little DIF is made by the mutants, and morphological development on agar stops after the cells have aggregated, but before a slug forms. In these DIF-deprived conditions, prespore cells can differentiate, but prestalk cells cannot.     

Dominance status and certain operants in a communal colony of rhesus macaques

This study was designed to test the hypothesis that in some species of primates individual differences in responsiveness to certain situations is related to dominance status. During the first phase of the study, the existence of a linear dominance hierarchy was confirmed by ratings of agonistic interactions. In the second phase, bar-pressing behavior was recorded on a cumulative recorder while the experimenter simultaneously rated, at 30-second intervals, all animals present in the research setting. Results indicated that dominance status was systematically related both to rate of bar-pressing and to duration of response blocks, with the more dominant animals bar-pressing at slower rates for longer blocks of time. The finding that individual differences in rate did not vary with social context suggests that dominance-related differences in responsiveness may be quite stable. Certain dominancerelated trends in the variation of social context in the research setting were also noted.