Seminal Fluid Production Research Articles

SPERM SURVIVAL IN FEMALE STALK-EYED FLIES DEPENDS ON SEMINAL FLUID AND MEIOTIC DRIVE

Sperm competition is common in many insect species; however, the mechanisms underlying differences in sperm precedence are not well understood. In the stalk-eyed fly, Cyrtodiopsis whitei (Diptera, Diopsidae), sperm precedence is influenced by the presence of sex chromosome meiotic drive. When drive-carrying males compete with non-driving males for fertilizations within a female, the number of progeny sired by drive males is significantly fewer than predicted by sperm mixing alone. Thus, drive males apparently suffer not only a reduction in the number of viable sperm produced, but also a reduction in sperm competitive ability. In this study, we manipulated the amount and source of seminal fluid and sperm received by females by interrupting copulations before sperm, but after seminal fluid, was transferred. We find that seminal fluid from another male influences the number of progeny sired by a drive-carrying male when both males mate with the same female. Sperm viability staining reveals that sperm from drive males are incapacitated by seminal fluid from other males within the female reproductive tract. These results suggest that multiple mating by females enables seminal fluid products to interact differentially with sperm and may reduce the transmission advantage of the drive chromosome.

Females receive a life-span benefit from male ejaculates in a field cricket.

Mating has been found to be costly for females of some species because of toxic products that males transfer to females in their seminal fluid. Such mating costs seem paradoxical, particularly for species in which females mate more frequently than is necessary to fertilize their eggs. Indeed, some studies suggest that females may benefit from mating more frequently. The effect of male ejaculates on female life span and lifetime fecundity was experimentally tested in the variable field cricket, Gryllus lineaticeps. In field crickets, females will mate repeatedly with a given male and mate with multiple males. Females that were experimentally mated either repeatedly or multiply lived more than 32% longer than singly mated females. In addition, multiply mated females produced 98% more eggs than singly mated females. Because females received only sperm and seminal fluid from males in the experimental matings, these life-span and fecundity benefits may result from beneficial seminal fluid products that males transfer to females during mating. Mating benefits rather than mating costs may be common in many animals, particularly in species where female mate choice has a larger effect on male reproductive success than does the outcome of sperm competition.

Cost of mating in Drosophila melanogaster females is mediated by male accessory gland products.

Female Drosophila melanogaster with environmentally or genetically elevated rates of mating die younger than controls. This cost of mating is not attributable to receipt of sperm. We demonstrate here that seminal fluid products from the main cells of the male accessory gland are responsible for the cost of mating in females, and that increasing exposure to these products increases female death rate. Main-cell products are also involved in elevating the rate of female egg-laying, in reducing female receptivity to further matings and in removing or destroying sperm of previous mates. The cost of mating to females may therefore represent a side-effect of evolutionary conflict between males.

L'endocytose de l'« androgen-binding protein » (ABP) par les cellules principales de l'épididyme chez le rat

The present study is based on the comparison between the radioautographic analysis of the fate of the androgen-binding protein purified from rat testes (HPLC) subsequently iodinated and injected into the epididymal lumen using a micromanipulator, and the biochemical analysis of the binding capacities of this molecule to soluble epididymal membrane extracts using HPLC and ultracentrifugation. The various experimental conditions used here allowed to demonstrate that ABP was internalized by the epididymal epithelium and to state that this internalization was not a non specific fluid phase endocytosis but a receptor-mediated-mechanism. Indeed, from a morphological stand point, the labeled ABP was associated rather with the membranes of the endocytic apparatus than with its content. In addition, from the two lumenal cell types able to resorb seminal fluid products, only the principal cells took up the labeled ABP. Our results clearly showed that this internalization was correlated with the presence of a 125I.ABP binding protein. Since the binding of this protein molecule to ABP was saturable and Calcium and pH dependent, it is strongly suggested that this molecule behaves as a receptor, the ligand (or one of the ligands) of which could be ABP.

Recommended biochemical parameters for routine semen analysis.

The measurement of biochemical markers in human seminal plasma is important in the evaluation of male infertility. We recommend the measurement of one representative substance for each organ involved in seminal fluid production as a routine diagnostic tool: The initial fructose level for seminal vesicular function, citrate or acid phosphatase for the prostate gland and free carnitine as an index of epididymal function. A biochemical analysis of seminal fluid enables us to detect disturbances of the male adnexal organs and may lead to more exact therapy.

Condoms Prevent Transmission of AIDS-Associated Retrovirus

<h3>To the Editor.—</h3> The majority of cases of acquired immunodeficiency syndrome (AIDS) have occurred after exposure to seminal fluid, blood, or blood products. It has been recommended that individuals avoid contact with seminal fluid through the use of prophylactic sheaths, although the proof that the virus could not passthrough these commercial products has not been established. In previous studies we demonstrated that herpesvirus could not pass through condoms.¹We have now performed similar studies to determine whether retroviruses would be retained by these materials. <h3>Report of a Study.—</h3> For the experiments, both a mouse retrovirus and the AIDS-associated retrovirus (ARV-2) were employed. A solution of tissue-culture medium containing either 10^7,8infectious mouse xenotropic type C retrovirus particles per milliliter or 10⁶infectious ARV-2 particles per milliliter was used.^2,3The plunger from a 12-mL syringe was placed inside the condom, to which was added 4 mL of the

Environmental Influences on Semen Output

Semen output characteristics of 7,858 ejaculates of 57 commercial Holstein sires in artificial insemination were analyzed to estimate effects of environment over 3-yr. Large differences existed between bulls, first and second ejaculates, and intervals between collections for all measures of semen output. Effects of age of bulls were greatest for sperm concentration per milliliter and total sperm output, peaking at 4 yr of age. Original semen volume was influenced less by age. December was the best month for total sperm production even though June and July were the months for most volume of seminal fluid production. Total sperm output was highest on Fridays and lowest on Wednesdays. Effects of temperature and humidity and changes in temperature and humidity on semen output were small and inconsistent. These results do not support the assumption that semen output could be increased in controlled environment conditions.