Co-Expression of Mannose-Ligand and Non-Nuclear Progesterone Receptors on Motile Human Sperm Identifies an Acrosome-Reaction Inducible Subpopulation

PROBLEM : To determine whether surface expression of receptors for progesterone and mannose can be used to identify spermatozoa likely to undergo an acrosome reaction after zona binding and to compare the reactivity of these receptors with naturally occurring sperm head-directed anti-sperm antibodies (ASAs). METHOD : Progesterone binding sites on the surface of fresh and capacitated motile human sperm in relation to acrosome status were visualized using a cell-impermeant progesterone. Free progesterone and/or mannose ligands were compared for percent sperm binding and ability to induce an acrosome reaction. Western blots of sperm proteins localized to the plasma membrane and surface proteins precipitated following passive transfer of serum ASAs were probed with progesterone-horseradish peroxidase. The effects of the same ASAs on ligand binding and on the induced acrosome reaction were examined. RESULTS : The two receptors are located in close proximity on a subset of capacitated motile sperm and are coordinately cleared from the plasma membrane overlying the acrosomal cap prior to exocytosis. The surface appearance of functional binding sites for each ligand, however, is regulated by different mechanisms and the progesterone receptor alone is specifically precipitated by ASAs. Passive transfer of ASAs to capacitated sperm selectively inhibits the progesterone-stimulated acrosome reaction but not the ionomycin-induced acrosome reaction or the ability of sperm to bind mannose ligands. CONCLUSIONS : Sperm from fertile donors incubated under capacitating conditions in vitro can be subdivided into acrosome reaction inducible and noninducible subpopulations on the basis of the co-expression or total absence of these receptors. The combined data indicate that reaction of sperm surface progesterone receptors with ASAs contributes to the acrosome reaction insufficiency observed in anti-sperm immune infertility.     

Carcinogenicity of Chloroform in Drinking Water to Male Osborne-Mendel Rats and Female B6C3F1 Mice

Carcinogenicity of Chloroform in Drinking Water to Male Osborne-MendelRats and Female B6C3F1 Mice. JORGENSON, T. A., MEIERHENRY, E.A., RUSHBROOK, C. J., BULL, R. J.AND ROBINSON, M. (1984). Fundam.Appl. Toxicol. 5, 760–769. The carcinogenic activity ofchloroform administered at 0, 200, 400, 900, and 1800 mg/literin drinking water was studied in male Osborne-Mendel rats andfemale B6C3F1 mice. A second control group was included in thestudy and was restricted to the water consumption of the high-dosegroup. Animals were maintained on study for 104 weeks. Groupsizes were adjusted at low doses such that a detectable tumorresponse would result at the lowest dose if there was a linearrelationship with dose, and the higher doses produced responsessimilar to previous carcinogenesis bioassays of chloroform.The primary finding was that chloroform increased the yieldof renal tubular adenomas and adenocarcinomas in male rats ina dose-related manner. For the high-dose group, which correspondedto a time-weighted average dose of 160 mg/kg per day for 104weeks, there was a 14% incidence of renal tubular adenomas andadenocarcinomas, vs 1% in the control group. This compares toa 24% incidence observed when 180 mg/kg per day of chloroformwas administered for 78 weeks in earlier studies. In contrast,chloroform in the drinking water of mice failed to increasethe incidence of hepatocellular carcinomas in female B6C3F1mice. The highest dose group received a time-weighted averagedose of 263 mg/kg for 104 weeks, resulting in a 5% combinedincidence of hepatocellular adenoma and carcinoma relative toa 6% incidence in the control groups. In a prior National CancerInstitute study an 80% incidence of hepatocellular carcinomaswas observed at 270 mg/kg per day for 78 weeks. These data indicatethat chloroform administered in drinking water is capable ofinducing cancer in the rat kidney. However, the lack of responsein the mouse liver when chloroform is supplied in the drinkingwater suggests that earlier reports of chloroform hepatocarcinogenesismay be related to some interaction with the mode of administration(corn oil gavage).     

Protein and mRNA analysis of myosin heavy chains in the developing avian pectoralis major muscle

While the existence of post-hatch and adult myosin heavy chain isoforms in the large, avian type IIB pectoralis major muscle has been clearly established, the number and nature of fast myosin heavy chains during in ovo development and the peri-hatch period have not been resolved. In the present study, developmental fast heavy chain proteins purified by high resolution anion-exchange have been characterized by sequence analysis of a unique CNBr peptide and by complementary mRNA analysis. The four proteins present at 15/16 days in ovo are shown to differ uniquely in primary structure. They correlate with heavy chains II, IV, VI and VII, characterized recently as major or minor species in adult fast muscles using similar methods. These four heavy chains are expressed in a time-dependent fashion from 8 to 16 days in ovo. At the mRNA level, heavy chain VI predominates until 12 days in ovo. Heavy chain IV mRNA is upregulated dramatically at 16 days in ovo preparatory to its protein's predominance in the peri-hatch period. Heavy chains II, IV and V (the post-hatch isoform which replaces heavy chain IV) have major roles in adult fast muscles. This revised version was published online in August 2006 with corrections to the Cover Date.