Worker-Born Males Are Smaller but Have Similar Reproduction Ability to Queen-Born Males in Bumblebees

Queen-worker conflict over the reproduction of males exists in the majority of haplodiplioidy hymenpteran species such as bees, wasps, and ants, whose workers lose mating ability but can produce haploid males in colony. Bumblebee is one of the representatives of primitively eusocial insects with plastic division labor and belongs to monandrous and facultative low polyandry species that have reproductive totipotent workers, which are capable of competing with mother queen to produce haploid males in the queenright colony compared to higher eusocial species, e.g., honeybees. So, bumblebees should be a better material to study worker reproduction, but the reproductive characteristics of worker-born males (WMs) remain unclear. Here, we choose the best-studied bumblebee Bombus terrestris to evaluate the morphological characteristics and reproductive ability of WMs from the queenless micro-colonies. The sexually matured WMs showed smaller in forewing length and weight, relatively less sperm counts but equally high sperm viability in comparison with the queen-born males (QMs) of the queenright colony. Despite with smaller size, the WMs are able to successfully mate with the virgin queens in competition with the QMs under laboratory conditions, which is quite different from the honeybees reported. In addition, there was no difference in the colony development, including the traits such as egg-laying rate, colony establishment rate, and populations of offspring, between the WM- and the QM-mated queens. Our study highlights the equivalent reproductive ability of worker-born males compared to that of queens, which might exhibit a positive application or special use of bumblebee rearing, especially for species whose males are not enough for copulation. Further, our finding contributes new evidence to the kin selection theory and suggests worker reproduction might relate to the evolution of sociality in bees.

MАR-test and Spermiological Research Indices

Antisperm antibodies are detected in 3% to 25% of cases in men and women diagnosed with infertility. They can also be diagnosed in 1–10% of healthy fertile men. The presence of a high titer of AST is one of the factors of male infertility, which can be «hidden», i. e. not cause symptoms and deterioration of the overall spermogram. The objective: to analyze the results of sperm testing in men with antisperm antibodies, which were detected by MAR-test. Material and methods. A retrospective analysis of the examination results of 555 men was conducted on the basis of the Medical Center for Infertility Treatment in Chernivtsi. Spermograms were examined according to WHO recommendations in 2000, using an inverted microscope Olympus CKX41 in a Broker chamber. Determination of the percentage of sperm coated with antisperm antibodies was performed using the MAR-test (MAR-test, MAR-mixed antiglobulin reaction). Results. If we calculate the percentage of patients in whom we assume the connection between the presence of antisperm antibodies and undertaken surgery, genital infections and allergy history, we get only 48.3% of cases. It has been found that most changes in sperm counts correlate with the percentage of sperm that are coated with IgG. These data indicate that increased IgG levels play an important role in the development of pathospermia. A negative medium-strength correlation was found between the percentage of Category A sperm and the percentage of IgG-coated sperm. Persistence of IgG in semen is accompanied by a probable decrease in the morphological quality of sperm. Conclusion. In 52% of patients it was not possible to establish the etiological factor for the presence of Ig in the ejaculate. It has been found that most changes in sperm counts correlate with the percentage of sperm that are coated with IgG. It has been determined that an increase in the level of IgA and IgG leads to a probable increase in the percentage of pathological sperm forms and decrease in sperm motility. In the presence of 30% of sperm that are coated with IgG, with a probability of 95%, the ejaculate of patients will have 100% of pathologicoalr mf s of sperm.

Male size mediates plastic response to winner-loser effects for some sexually selected traits

The outcomes of fights often affect the fitness of males by determining their access to mates. ‘Winner-loser’ effects, where winners often win their next contest, but losers tend to lose, can therefore influence how males allocate resources towards traits under pre- and post-copulatory sexual selection. We experimentally manipulated the winning/losing experiences of size-matched male Gambusia holbrooki for either a day, a week or three weeks to test whether prior winning/losing experiences differentially affect the plasticity of male investment into either mating effort (pre-copulatory) or ejaculates (post-copulatory). Winners had better pre-copulatory outcomes than losers for three of the four traits we measured: number of mating attempts, number of successful attempts, and time spent with the female. Winners also produced faster sperm than losers, but there was no difference in total sperm counts. Interestingly, absolute male size, an important predictor of fighting success, mediated the effect of winning or losing on how long males then spent near a female. Smaller winners spent more time with the female than did larger winners, suggesting that how males respond to prior social experiences is size-dependent. We discuss the general importance of controlling for inherent male condition when comparing male investment into condition-dependent traits.

Hypoxia-induced alteration of RNA modifications in the mouse testis and sperm

Hypobaric hypoxia as an extreme environment in a plateau may have deleterious effects on human health. Studies have indicated that rush entry into a plateau may reduce male fertility and manifest in decreased sperm counts and weakened sperm motility. RNA modifications are sensitive to environmental changes and have recently emerged as novel post-transcriptional regulators in male spermatogenesis and intergenerational epigenetic inheritance. In the present study, we generated a mouse hypoxia model simulating the environment of 5500 meters in altitude for 35 days, which led to compromised spermatogenesis, decreased sperm counts, and an increased sperm deformation rate. Using this hypoxia model, we further applied our recently developed high-throughput RNA modification quantification platform based on LC–MS/MS, which exhibited the capacity to simultaneously examine 25 types of RNA modifications. Our results revealed an altered sperm RNA modifications signature in the testis (6 types) and mature sperm (11 types) under the hypoxia model, with 4 types showing overlap (Am, Gm, m7G, and m22G). Our data first drew the signature of RNA modification profiles and comprehensively analyzed the alteration of RNA modification levels in mouse testis and sperm under a mouse hypoxia model. These data may be highly related to human conditions under a similar hypoxia environment.