Reproductive biology of the guitarfish <Emphasis Type="Italic">Rhinobatos hynnicephalus</Emphasis> (Batoidea: Rhinobatidae) in Ariake Bay,Japan

Size at sexual maturity, reproductive cycle, and fecundity of the guitarfish, Rhinobatos hynnicephalus, were examined in Ariake Bay, Japan. Females reached sexual maturity at a larger size than males [total length (TL) at 50% sexual maturity: males, 431 mm; females, 476 mm]. Monthly gonadosomatic indices of males decreased abruptly from July to August. Histological examinations confirmed the presence of mature spermatozoa in the testes in July, with semen in seminal vesicles in July and August. Preovulatory ova were observed in females with near-term embryos in August. Parturition occurred in August, immediately followed by mating, ovulation, and fertilization. Gestation period is approximately 1 year. Fertilized uterine eggs without embryonic development were present throughout the annual reproductive cycle. Embryonic development began in June and ended in August, indicating that R. hynnicephalus undergoes embryonic diapause (9 months). Fecundity increased with TL and ranged from 1 to 9 (mean, 4.4) embryos per litter.     

Reproductive performance of Farafra ewes in the subtropics

The present study was carried out to assess the reproductive performance of Farafra ewes—a breed with potential economic importance in the subtropics. A total of 262 ewes were categorized according to age, parity, and postpartum interval. Ewes were introduced for breeding in fall, winter and late spring seasons. Fertility, prolificacy, lamb birth weight, and ultrasonic fetal parameters were recorded. Results obtained showed that litter size was increased with age and parity. Lamb birth weight was affected by season. None of the parameters studied had a clear-cut effect on fertility. However, an interaction between season and parity was detected. Measurement of fetal size in the first half of gestation did not predict birth weight. The obtained data represents the first record of the reproductive performance of Farafra ewes in the subtropics, which could be used to anticipate their performance in different seasons.     

Hedgerows as an environment for forest plants: a comparative case study of five species

Many areas in Europe are dominated by agricultural land use, and as a consequence, many typical forest plant species suffer from habitat loss and fragmentation. Hedgerows, one of the common elements of rural landscapes, have been considered as potential refuges for these species. The main objective of this study was to examine whether forests and hedgerows differ in environmental conditions, and whether important life-history attributes of the populations differ between the two habitat types. We selected five species commonly found in the region in both forests and hedgerows (Adoxa moschatellina, Anemone nemorosa, Circaea lutetiana, Polygonatum multiflorum and Stellaria holostea), and sampled data on 10 populations of each species in each habitat type, including measurements of light and various soil factors. Hedgerows had higher relative light availability and tended to have higher soil nutrient contents and lower soil water values than forests. The comparison of plant performance values between habitat types did not show consistent patterns across species. Anemone and Polygonatum performed equally well in hedgerows and forests, whereas Stellaria appeared to have a higher fitness in hedgerows. In contrast, Circaea showed a higher reproduction under forest conditions. For Adoxa, the results were somewhat contradictory: whereas the reproductive output of this species was higher in forests, population density was higher in hedgerows. The abiotic factors most closely related to the performance values were relative light and soil water availability. The majority of plant performance values did not differ between hedgerows and forests. We therefore conclude that the tested forest species are capable of growing also in hedgerows and will survive equally well in forest and its “surrogate” habitat.     

Resource-dependent reproductive adjustment and the stability of consumer-resource dynamics

This study explored a consumer-resource model including reproductive and nonreproductive subpopulations of the consumer to consider whether resource-dependent reproductive adjustment by the consumer would stabilize consumer-resource dynamics. The model assumed that decreasing (increasing) resource availability caused reproductive suppression (facilitation), and that the reproductive consumer had a higher mortality rate than the nonreproductive one (i.e., a trade-off between reproduction and survival). The model predicted that the variability would be reduced when the consumer had a strong tendency to suppress reproduction in response to low resource availability or when the cost of reproduction was high, although consumer extinction became more likely. Furthermore, when the consumer-resource dynamics converged to limit cycles, reproductive adjustment enhanced the long-term average of the consumer density. It was also predicted that if reproductive suppression enhanced resource consumption efficiency (i.e., a trade-off between reproduction and foraging), then it would destabilize the system by canceling the stabilizing effect of the reproductive adjustment itself. These results suggest that it is necessary not only to identify the costs of reproduction, but also to quantify the changes in individual-level performances due to reproduction in order to understand the ecological consequences of reproductive adjustment.     

The essential roles of TGFB1 in reproduction

Transforming growth factor beta 1 (TGFB1) is implicated as a key regulator of the development and cyclic remodelling characteristic of reproductive tissues. The physiological significance of TGFB1 in reproductive biology and fertility has been extensively examined in Tgfb1 null mutant mice. Genetic deficiency in TGFB1 causes perturbed functioning of the hypothalamic–pituitary–gonadal axis, inhibiting luteinising hormone (LH) synthesis and leading to downstream effects on testosterone production in males and estrous cycle abnormalities in females. Oocyte developmental incompetence, accompanied by early embryo arrest as well as altered pubertal mammary gland morphogenesis are observed. In addition to LH and testosterone deficiency, male Tgfb1 null mice demonstrate complete inability to mate with females, associated with failure to initiate and/or sustain successful penile intromission or ejaculation. These studies demonstrate the profound significance of TGFB1 in male and female reproductive physiology, and provide a foundation for exploring the significance of this cytokine in human infertility and sexual dysfunction.     

生物信息学方法预测蛋白质相互作用网络中的功能模块

蛋白质相互作用是大多数生命过程的基础。随着高通量实验技术和计算机预测方法的发展,在各种生物中已获得了数目十分庞大的蛋白质相互作用数据,如何从中提取出具有生物学意义的数据是一项艰巨的挑战。从蛋白质相互作用数据出发获得相互作用网络进而预测出其中的功能模块,对于蛋白质功能预测、揭示各种生化反应过程的分子机理都有着极大的帮助。我们分类概括了用生物信息学预测蛋白质相互作用功能模块的方法,以及对这些方法的评价,并介绍了蛋白质相互作用网络比较的一些方法。     

Reproductive toxicologic evaluations of Bulbine natalensis Baker stem extract in albino rats

The effects of oral administration of aqueous extract of Bulbine natalensis Baker stem at daily doses of 25, 50, and 100 mg/kg body weight on the reproductive function of Wistar rats were evaluated. The indices of mating and fertility success as well as quantal frequency increased after 7 days of treatment in all the dose groups except the 100 mg/kg body weight group. The number of litters was not statistically different (P > 0.05) from the control. Whereas the absolute weights of the epididymis, seminal vesicle, and prostate were not affected, that of the testes was significantly increased. The epididymal sperm count, motility, morphology, and viscosity were not different from the control after 7 days of treatment. The male rat serum testosterone, progesterone, luteinizing hormone, and follicle-stimulating hormone significantly increased in the 25 and 50 mg/kg body weight groups, whereas the estradiol concentration decreased significantly at all the doses. The extract dose of 100 mg/kg body weight decreased the serum testosterone and progesterone levels in male rats. The prolactin concentration was not affected by all the doses. All the indices of reproduction, maternal, embryo/fetotoxic, teratogenic, and reproductive hormones in the female rats were not statistically different from that of their control except the resorption index, which increased at the dose of 100 mg/kg body weight of the extract. Histologic examination of the cross section of rat testes that received the extract at all the doses investigated revealed well-preserved seminiferous tubules with normal amount of stroma, normal population of spermatogenic and supporting cells, as well as normal spermatocytes within the lumen. The results revealed that the aqueous extract of Bulbine natalensis stem at doses of 25 and 50 mg/kg body weight enhanced the success rate of mating and fertility due to increased libido as well as the levels of reproductive hormones in male rats. The absence of alterations in the reproductive parameters of female rats at doses of 25 and 50 mg/kg body weight of Bulbine natalensis stem extract suggest that the extract is “safe” for use at these doses by females during the organogenic period of pregnancy, whereas the extract dose of 100 mg/kg body weight portends a negative effect on some reproductive functions of male and female rats.     

Reproductive success of wild Lesser Rheas (Pterocnemia -Rhea- pennata pennata) in north-western Patagonia, Argentina

We studied the reproductive success of a wild Lesser Rhea population (Pterocnemia -Rhea- pennata pennata) during two reproductive seasons (2004/2005 and 2005/2006) in north-western Patagonia, Argentina. The parameters recorded included population and nest density, clutch size, hatching success, chick survival (up to 3 months of age) and percentage of chicks that reached the juvenile stage after the winter. We also estimated the percentage of males that attempted to nest and of those that were successful (those producing at least one chick), daily nest mortality rates (DNMR) at different stages of the nesting cycle and the probability that an egg that has been recently laid will produce a chick. On average, both years pooled, the density of this population of Lesser Rheas was 1.55 ± 0.2 individuals/km² (SE), nest density was 0.17 ± 0.04 per km ² , clutch size was 20.8 ± 6.4 eggs, hatching success was 74.4% ± 11.3, Mayfield’s probability of an egg that will produce a chick was 0.64, chick survival was 65.4% ± 14.5 and percentage of chicks that reached the juvenile stage was 26.3%. Nearly a quarter of Lesser Rhea males in the population attempted to nest during a breeding season, and the DNMR was significantly higher during the laying stage (most nest failures were due to anthropogenic disturbances related to livestock raising activities). Nesting success, hatching success, and chick survival of Lesser Rheas were higher than those of their most closely related species, the Greater Rhea (Rhea americana), whereas the percentage of chicks that reached the juvenile stage was similar due to high winter mortalities of chicks. We suggest that the increase in reproductive effort is a strategy of this species to overcome environmental constraints.     

The effect of photoperiod on the reproductive development of the northern bay scallop, Argopecten irradians irradians

One-year-old bay scallops, Argopecten irradians irradians (58 ± 2 mm, 22 ± 1 g live weight) were exposed to four replicated photoperiod treatments (24D, 8L:16D, 16L:8D, and 24L where D = dark hours, L = light hours) in order to measure the effect on gonad weight and maturation during the conditioning process. Results indicated that day-lengths of more than 8 h are necessary to promote gonad maturation in bay scallops. After 6 wk, the mean gonad weight for scallops in the 16-h and 24-h light regimes was similar at 0.6 ± 0.1 g dry weight compared to a mean of 0.2 ± 0.1 g dry weight for those in the 8-h and 0-h light regimes. Histological assessment indicated significantly more follicular tissue development in both the male and female portion of the gonad in the two longer photoperiod treatments. Overall, gamete maturity was highest for the scallops in the 16-h light regime; the incidence of mature eggs was 50% compared to 35% in the 24-h light regime, 20% in the 8-h light regime and 10% in the 0-h light regime. Assessment of feeding rates indicated no significant difference in algal cell consumption among treatments. Total dry tissue weight doubled over the 6-wk conditioning trial with no significant differences among treatments. One-year-old bay scallops appear to be non-responsive to conditions suitable for gonad maturation (i.e. appropriate temperature and food levels) unless they receive more than 8 h of light exposure. This finding has important implications for northern hatcheries which typically condition broodstock indoors during the early spring.