Patterns of Sperm Transfer in the Golden Orb‐Weaver Nephila edulis

Sperm competition studies typically identify copulation duration as an important predictor of paternity as it may determine the quantity of sperm transferred and thus paternity success. This study explores the relationship between copulation duration, male body size, male age and sperm transfer in the golden orb‐weaving spider, Nephila edulis. Paternity in this species is strongly associated with the relative frequency and duration of copulation, which is also influenced by male size. We determined the number of sperm transferred during copulation, by performing sperm counts in both the male copulatory organs (palps) and female sperm receptacle (spermatheca) of recently mated pairs. The total number of sperm recorded (the sum in the male palps and female spermathecae) was greater for younger males than older males, but did not vary with male body size. In general, younger males transferred more sperm and a greater proportion of their sperm supplies than older males and, among these younger males, larger individuals transferred more sperm. However, there were no significant size effects for older males. More sperm was transferred with longer copulations, but in contrast with previous studies, we found that larger males copulated for longer. The rate of sperm transferred was negatively correlated with the duration of copulation, suggesting that the variation in copulation duration in N. edulis may represent strategic investment by males to alter patterns of paternity, in addition to transferring additional sperm.     

Effects of Age and Experience on Male Mate Choosiness

Mate choosiness by males has been documented in many taxa but we still do not know how it varies with age even though such variation can be important for our understanding of sexual selection on females. Theory provides conflicting predictions: young males, who are less attractive to females than older males, may be less choosy, or older males, who face fewer expected future mating opportunities, may be less choosy. In our experiments with fruit flies (Drosophila melanogaster), young (1‐d‐old) males spent relatively less time courting recently mated females than did mature (4‐d‐old) males. Overall, there was a gradual decline in male mate choosiness from age 1–7 d. As male age was correlated with the duration of deprivation from females, we tested for the effect of deprivation and found that same‐age males previously exposed to females were choosier than female‐deprived males. We also assessed key male parameters that could affect choosiness and found that, compared to mature males, young males were less attractive to females, less competitive in intramale interactions and less fertile. Although the lesser attractiveness and competitiveness should select for lesser mate choosiness in young males, their limited fertility and more expected future mating opportunities seem to override the other factors and lead to high mate choosiness in young males. Overall, our data indicate that young males just after reaching sexual maturity are choosy and that subsequent exposure to females can maintain high levels of male mate choosiness with age. Hence, males can contribute much more to sexual selection than previously appreciated.     

Generation of fertile offspring from Kitw/Kitwv mice through differentiation of gene corrected nuclear transfer embryonic stem cells

Genetic mutations could cause sperm deficiency, leading to male infertility. Without functional gametes in the testes, patients cannot produce progeny even with assisted reproduction technologies such as in vitro fertilization. It has been a major challenge to restore the fertility of gamete-deficient patients due to genetic mutations. In this study, using a Kit^w/Kit^wv mouse model, we investigated the feasibility of generating functional sperms from gamete-deficient mice by combining the reprogramming and gene correcting technologies. We derived embryonic stem cells from cloned embryos (ntESCs) that were created by nuclear transfer of Kit^w/Kit^wv somatic cells. Then we generated gene-corrected ntESCs using TALEN-mediated gene editing. The repaired ntESCs could further differentiate into primordial germ cell-like cells (PGCLCs) in vitro. RFP-labeled PGCLCs from the repaired ntESCs could produce functional sperms in mouse testes. In addition, by co-transplantation with EGFP-labeled testis somatic cells into the testes where spermatogenesis has been chemically damaged or by transplantation into Kit^w/Kit^wv infertile testes, non-labeled PGCLCs could also produce haploid gametes, supporting full-term mouse development. Our study explores a new path to rescue male infertility caused by genetic mutations.     

The effects of prenatal exposure to a 900-MHz electromagnetic field on the 21-day-old male rat heart

Abstract

The growing spread of mobile phone use is raising concerns about the effect on human health of the electromagnetic field (EMF) these devices emit. The purpose of this study was to investigate the effects on rat pup heart tissue of prenatal exposure to a 900 megahertz (MHz) EMF. For this purpose, pregnant rats were divided into experimental and control groups. Experimental group rats were exposed to a 900?MHz EMF (1?h/d) on days 13–21 of pregnancy. Measurements were performed with rats inside the exposure box in order to determine the distribution of EMF intensity. Our measurements showed that pregnant experimental group rats were exposed to a mean electrical field intensity of 13.77?V/m inside the box (0.50?W/m²). This study continued with male rat pups obtained from both groups. Pups were sacrificed on postnatal day 21, and the heart tissues were extracted. Malondialdehyde, superoxide dismutase and catalase values were significantly higher in the experimental group rats, while glutathione values were lower. Light microscopy revealed irregularities in heart muscle fibers and apoptotic changes in the experimental group. Electron microscopy revealed crista loss and swelling in the mitochondria, degeneration in myofibrils and structural impairments in Z bands. Our study results suggest that exposure to EMF in the prenatal period causes oxidative stress and histopathological changes in male rat pup heart tissue.     

The production of female sex pheromone in Bactrocera oleae (Rossi) young males does not influence their mating chances

In Bactrocera oleae females attract males, which is in contrast to the majority of Tephritidae. However, the major component of the secretion of the female rectal ampulla glands, 1,7‐dioxaspiro‐[5,5]‐undecane (DSU), was also isolated from the glands of young males. The DSU produced by females and young males attracts males, but not females. In this study, we investigated the role of the production of DSU in young males. The mating performances of young and old males were evaluated, as well as the male‐male courtships by old males oriented at young and old males. Young males were found not to have a mating advantage. Young males were courted more by other males. Frame‐by‐frame analysis of male wing vibrations showed that this behavior did not differ when oriented at females and young males, highlighting that young males are perceived as females by the courting males. Overall, the production of DSU in young B. oleae males did not seem to be a case of female chemical mimicry. The hypothesis that young olive fruit fly males could benefit indirectly from the DSU production, simply distracting mature males away from females, is discussed.     

大豆细胞核雄性不育基因研究进展

雄性不育是指植物雄蕊不能正常生长和产生有活力花粉粒的现象。利用雄性不育突变体开展杂交育种工作,是快速提高作物单产的有效途径。目前,通过杂种制种已大幅度提高了水稻(Oryza sativa L.)、玉米(Zea mays L.)和小麦(Triticum aestivum L.)等作物的产量。大豆(Glycinemax(L.)Merr.)作为自花授粉作物,通过人工去雄生产杂交种子不仅困难而且经济上不可行。由于适用于杂交种生产的不育系资源短缺,目前大豆还没有实现大规模杂种优势利用。因此,快速实现大豆杂种优势利用迫切需要鉴定稳定的大豆雄性不育系统。本文总结了大豆细胞核雄性不育(genic male sterility, GMS)突变体及不育基因研究进展,同时结合拟南芥(Arabidopsis thaliana)、水稻和玉米中已报道的细胞核雄性不育基因,从反向遗传学的角度,为大豆核雄性不育基因的鉴定提供依据。     

Prenatal and pubertal exposure to 17α-ethinylestradiol cause morphological changes in the prostate of old gerbils

This study evaluated such as exposure to ethinylestradiol during the prenatal (18th–22nd day) and pubertal (42nd–49th day) periods acts on the male ventral prostate and female prostate of 12-month old gerbils. We performed the analysis to serum hormone levels for estradiol and testosterone. The prostates were submitted to morphometric and immunohistochemical analyses. Exposure to ethinylestradiol during these developmental periods decreased the testosterone serum levels in males and increased the estradiol serum levels in females. Morphologically, prostate intraepithelial neoplasia and disorders in the arrangement of the fibrous components were observed in the prostate glands of both sexes of gerbil exposed to ethinylestradiol during development periods. In the male prostate, the ethinylestradiol promoted decreased in the frequency of positive epithelial cell for androgen receptor (AR) and increased the frequency of positive stromal cell for estrogen receptor α. However, in the female prostate, this synthetic estrogen caused AR upregulation and increased cell proliferation. This study shows that the exposure to ethinylestradiol during development phases alters the morphology and the hormonal signaling in the male and female prostates of old gerbils, confirming the action of ethinylestradiol as endocrine disruptor.     

青花菜细胞质雄性不育相关miRNA的鉴定与表达特征分析

植物miRNA是一类内源小分子RNA,在花粉发育和育性调控中具有重要作用。该研究利用高通量测序技术构建了青花菜细胞质雄性不育系及其保持系花蕾的sRNA文库,并通过qRT PCR技术检测育性相关的miRNAs及其预测靶基因的表达特征,为深入探讨miRNA调控青花菜育性机制提供理论依据。结果表明：(1)在青花菜中共鉴定到181个保守miRNA和8个新型miRNA,差异表达miRNA共47个,其中24个已知miRNAs和4个新型miRNAs表达上调,其余为表达下调;发现2个差异miRNA只在不育系中表达,7个差异miRNA为保持系所特有。(2)生物信息学分析表明,共鉴定到2个关联的miRNA mRNA对［miR859 1靶向的花粉外壁蛋白基因(T2/Unigene_BMK.21608)和miR5174e 1调控的氨基酸通透酶基因(T2_Unigene_BMK.31772)］,2个miRNA均负向调控相应的靶基因,均可参与青花菜小孢子发育以及雄性不育的发生过程。(3)qRT PCR分析显示,miR159a 1、miR164a 1、miR319a 1和miRn11在青花菜不育系中的表达量高于其保持系,其中miR164a 1、miR319a 1和miRn11的表达水平随着花蕾的发育不育系逐渐降低,而在保持系的表达呈上升趋势;miR319a 1和miR397a 2在雄蕊中的表达量高,而在其他部位的表达量较低,且miR397a 2在青花菜不育系中的表达量显著低于保持系。研究推测,miRNA可能是通过抑制雄性不育相关的PPR基因表达、调控LAC基因的表达以及调节激素和Ca²⁺介导的信号转导通路等,从而导致青花菜雄性不育的发生。