Influences of weather on reproductive function in female Song sparrows, Melospiza melodia

Prolonged and severe periods of inclement weather can retard gonadal development in early spring or disrupt the breeding cycle in summer. Previous investigations on the endocrine responses of free-living avian species to storms have been restricted almost entirely to males. This communication presents the endocrine responses of free-living female Song sparrows, Melospiza melodia, during gonadal recrudescence after a severe winter, and during storms in early spring and summer. As in males, gonadal recrudescence was delayed by the severe winter weather, and this effect was exacerbated by an aseasonal snow storm in early spring. Unlike males, female Song sparrows did appear to be stressed by this snow storm, since body mass and fat deposit decreased, and plasma levels of corticosterone increased. A second storm in early summer did not, however, prove to be stressful to females, although males were apparently stressed by the same storm. At the time the early summer storm occurred, young had been fledged and were being fed mostly by the male. Females begin preparing for a second clutch of eggs and do not feed fledglings to the same extent as males. Thus it is possible that males are stressed by storms at this time, because they are feeding several young as well as themselves during a period of reduced availability of food, whereas females are feeding themselves only. These data suggest that, not only do the endocrine responses to inclement weather vary in relation to stage in the reproductive cycle when storms strike, but also that there are sex differences in those responses.     

Cloacal bacterial diversity increases with multiple mates: evidence of sexual transmission in female common lizards

Sexually transmitted diseases have often been suggested as a potential cost of multiple mating and as playing a major role in the evolution of mating systems. Yet there is little empirical data relating mating strategies to sexually transmitted microorganisms in wild populations. We investigated whether mating behaviour influences the diversity and composition of cloacal assemblages by comparing bacterial communities in the cloaca of monandrous and polyandrous female common lizards Zootoca vivipara sampled after the mating period. We found that polyandrous females harboured more diverse communities and differed more in community composition than did monandrous females. Furthermore, cloacal diversity and variability were found to decrease with age in polyandrous females. Our results suggest that the higher bacterial diversity found in polyandrous females is due to the sexual transmission of bacteria by multiple mates. The impact of mating behaviour on the cloacal microbiota may have fitness consequences for females and may comprise a selective pressure shaping the evolution of mating systems.     

Hormonal response of free-living male white-crowned sparrows to experimental manipulation of female sexual behavior

In free-living male white-crowned sparrows (Zonotrichia leucophrys), plasma levels of testosterone, 5α-dihydrotestosterone (DHT), and luteinizing hormone (LH) decrease precipitously at onset of incubation. The hypothesis that this decrease is a response to the simultaneous cessation of estradiol-dependent solicitation displays by females was tested in an experiment on free-living pairs. Solicitation displays were prolonged by implanting females with subcutaneous estradiol capsules and releasing them. Subsequent capture and blood sampling of the mates of these females showed that they had significantly higher plasma levels of testosterone and DHT than did control males, but results for LH were equivocal. Nevertheless, these results support the above hypothesis and suggest that hormone-behavior interactions are important even in free-living animals exposed to the entire spectrum of environmental information.     

Proteasome activity in tumors of female reproductive system

Proteasomes (multiproteinase protein complexes) are known to play an important role in cancer pathogenesis, however, few information about their activity in human tumor tissues is available so far. We studied chymotrypsin-like activity of proteasomes in tissues of breast cancer (BC) and endometrial cancer (EC). The chymotrypsin-like total proteasome activity and the 20S and 26S proteasome activity in malignant tissues were shown to be significantly higher in malignant tumors than in normal tissues. No increase in proteasome activity was registered with larger tumor size in both BC and EC, whereas proteasome activity was changed with respect to the extent of tumor involvement. In breast cancer tissues, significant reductions in the total and the 26S proteaome activities were observed in tumors with regional lymph node metastases as compared to tumors without metastases. In endometrial cancer tissues, the total proteasome activity and the 20S and 26S proteasome activities were increased as the depth of myometrial invasion. The data obtained indicate that the proteasome acyivity is significantly changed in the process of cancerogenesis and further study is needed to develop new additional prognostic criteria and effective anti-tumor agents in molecular-directed therapy.     

Proteasome activity in tumors of the female reproductive system

Although proteasomes (multiproteinase protein complexes) are known to play an important role in cancer pathogenesis, there is little information about their activity in human tumor tissues. The chymotrypsin-like activity of proteasomes in breast cancer (BC) and endometrial cancer (EC) tissues was studied. It was shown that the chymotrypsin-like total proteasome activity and the 20S and 26S proteasome pool activities were significantly higher in malignant than in normal tissues. An increase in the size of either BC or EC tumors did not affect the proteasome activity, whereas the propagation of a malignant process did. If compared with BC non-metastatic tumors, a reliable decrease in the total activity and the 26S proteasome activity was observed in BC tumors with regional lymph node metastases. In EC tissues, the total proteasome activity and the 20S and 26S proteasome pool activities increased when the depth of tumor myometrial invasion grew. These data demonstrated that the proteasome activity significantly varied in the process of carcinogenesis. Further proteasome studies could serve as the basis for the development of new criteria for prognosis of female reproductive system cancer and the search for effective antitumor agents in targeted therapy.     

Evaluation of sexual behaviour in rams in relation to their reproductive capacity

The objective of the study was to determine the individual differences in sexual activity of rams. In total, 374 observations were made on 17 rams (22 for each ram). The average duration of mating for all rams was 70.9 s, ranging from 30.0 to 166.7 s for particular rams. The average duration of mating for a group of ten more active rams (MAR) was 49.3 s, while for a group of seven less active rams (LAR) it was 101.8 s, the difference being highly significant. Significant differences were also found with respect to the average number of mounts per ejaculation, both between individual rams (mean 2.36) and between group MAR (2.20) and LAR (2.60). The percentage of failure, defined as copulations without ejaculation, was significantly higher in group LAR (11.1%) than in group MAR (2.5%), indicating that the rams of group MAR copulate much more efficiently than the other males. The lambing results obtained from service during the first oestrus did not show significant differences between groups MAR and LAR, neither with respect to their fertility nor to the lambing rate.     

Effect of female sexual displays on the endocrine physiology and behaviour of male white-crowned sparrows, Zonotrichia leucophrys

In photoperiodic birds, endocrine responses to behavioural interactions between males and females may be involved in temporally "fine-tuning" the onset of reproduction to yearly variations in the environment. This study examined the endocrine and behavioural responses of male White-crowned sparrows ( Zonotrichia leucophrys ) to changes in the endocrine state of the female, as signalled by changes in her behaviour. Males on different photoperiodic regimes were paired with oestrogen-treated, sexually receptive females. Males exposed to gonadostimulatory long days mounted and copulated with oestrogen-treated females even before gonadal development was complete. These males had higher plasma levels of testosterone and luteinizing hormone and maintained enlarged testes longer than control males paired with untreated, nonreceptive females. Males maintained on nonstimulatory short days also mounted oestrogen-treated females; however, testes of these males remained nonfunctional and their plasma levels of testosterone and luteinizing hormone were basal. Thus, reproductive function of photostimulated males is profoundly affected by changes in the endocrine state and behaviour of the female. However, male sexual behaviours are expressed in response to visual and auditory stimuli from the female regardless of male hormonal condition or photoperiodic treatment.     

Cutaneous immune activity varies with physiological state in female house sparrows (Passer domesticus)

Many vertebrates show seasonality in immune defenses, perhaps because of trade-offs with other physiological processes. Trade-offs between reproduction and immune function have been well studied, but how other life cycle events such as molt affect immune function remains unclear. Here, we hypothesize that one possible explanation is that accumulative dissociated processes (e.g., resource deficits generated over the long term by physiological processes) can have delayed effects on immune activity. To test this hypothesis, we compared cutaneous immune responses in groups of captive female house sparrows (Passer domesticus) photoperiodically induced into six different life cycle stages. We predicted that if delayed trade-offs occur, immune activity would be reduced after a mature life state was reached (e.g., postmolt) and not just compromised when other tissues were actively growing (instantaneous trade-off). We found evidence for both types of trade-offs: immune responses were weakest in sparrows that had just completed postnuptial molt, but they were also weak in birds growing reproductive tissues or feathers. Birds in mature reproductive states or light molt had strong immune responses comparable with birds in a nonbreeding/nonmolting state. Altogether, our results indicate that immune activity in female house sparrows can be influenced by both instantaneous and delayed trade-offs.     

Maternal influences on the sexual behavior and reproductive success of the female rat

In many species, including humans, there is evidence for parental effects on within-sex variations in reproductive behavior. In the present studies we found that variations in postnatal maternal care were associated with individual differences in female sexual behavior in the rat. Females born to and reared by dams that showed enhanced pup licking/grooming (i.e., High LG mothers) over the first week postpartum showed significantly reduced sexual receptivity and alterations in the pacing of male mounting (i.e., longer inter-intromission intervals) observed in a paced mating test. There were minimal effects on the sexual behavior of the male offspring. The female offspring of High LG mothers showed a reduced lordosis rating, a decreased mount:intromission ratio, received fewer ejaculations and were less likely to achieve pregnancy following mating in the paced mating context. The data suggest maternal influences on the sexual development of the female rat that are functionally relevant for reproductive success. Together with previous studies these findings imply that maternal care can ‘program’ reproductive strategies in the female rat.     

Induction of sexual activity in female camels during the nonbreeding season

Sixteen anestrous adult female camels (Camelus dromedarius ) in good health and with inactive ovaries were selected from the herd during the month of June (non-breeding season). The camels were randomly divided into 4 equal groups. To induce ovarian activity, camels in Groups I,II and III were given an intramuscular injection of 250 mg hydroxyprogesterone hexanoate followed by 1000 IU eCG on days 2 and 3 of treatment. The camels were mated on Day 5 after the last eCG injection. Ovulation in Groups II and III was induced by intravenous administration of 3000 IU hCG and 40 mcg GnRH, respectively. Group IV was administered saline and served as the control. Periodic examinations per rectum were performed to explore the status of the ovaries. Blood samples were collected at 8 different stages and sera were analyzed for estradiol 17-B and progesterone using specific RIA kits. All camels in the control and treated groups were mated successfully. Levels of estradiol 17-B did not exhibit any particular trend. Blood progesterone levels suggested ovulation in 2 camels (50%) in Group I and in 3 camels (75%) in each of Groups of II and III. This was confirmed by presence of CL in the ovary during per rectum examination. No camel ovulated in the control group. One camel conceived in each of Groups I and III.     

Influence of inflorescence size on sexual expression and female reproductive success in a monoecious species

Sex allocation theory forecasts that larger plant size may modify the balance in fitness gain in both genders, leading to uneven optimal male and female allocation. This reasoning can be applied to flowers and inflorescences, because the increase in flower or inflorescence size can differentially benefit different gender functions, and thus favour preferential allocation to specific floral structures. We investigated how inflorescence size influenced sexual expression and female reproductive success in the monoecious Tussilago farfara, by measuring patterns of biomass, and N and P allocation. Inflorescences of T.?farfara showed broad variation in sex expression and, according to expectations, allocation to different sexual structures showed an allometric pattern. Unexpectedly, two studied populations had a contrasting pattern of sex allocation with an increase in inflorescence size. In a shaded site, larger inflorescences were female-biased and had disproportionately more allocation to attraction structures; while in an open site, larger inflorescences were male-biased. Female reproductive success was higher in larger, showier inflorescences. Surprisingly, male flowers positively influenced female reproductive success. These allometric patterns were not easily interpretable as a result of pollen limitation when na?vely assuming an unequivocal relationship between structure and function for the inflorescence structures. In this and other Asteraceae, where inflorescences are the pollination unit, both male and female flowers can play a role in pollinator attraction.     

The reproductive success of female coypus in a feral population: variation in relation to age, fat reserves and the availability of mates

An introduced population of coypus ( Myocastor coypus ) has lived in the wetlands of eastern England since the 1930s. Female reproductive biology has been studied over a 17 year period using information from post mortem examinations of animals caught in a trapping campaign. Females breed throughout the year and produce litters. Litter size at conception and prenatal mortality vary in relation to the mother's age and nutrient reserves. Some embryos are resorbed and some die at or shortly after birth, perhaps to reduce litters to a size that the mother can support. In addition, selective mortality of male and female embryos may allow mothers to manipulate offspring sex ratio (Gosling, 1986). The proportion of females that have litters each year also varies in relation to population density. This variation may be mediated by both the food supply and the availability of mates (Gosling and Baker, in press).     

Floral display size and spatial distribution of potential mates affect pollen deposition and female reproductive success in distylous Pulmonaria officinalis (Boraginaceae)

In animal‐pollinated plants, both the spatial distribution of flowering individuals and the number of flowers that an individual displays affect pollen deposition rates and female reproductive success. Heterostylous species are likely to be particularly sensitive to the contingencies of spatial distribution, as they are reproductively subdivided into distinct mating groups, which usually exhibit self‐ and intra‐morph incompatibility and differ in floral morphology. In this paper, we explore the joint effects of both spatial distribution of potential mates and floral display size on morph‐specific pollen deposition rates and seed set patterns in two natural populations of Pulmonaria officinalis, a distylous species with a weak self‐incompatibility system. Both total stigmatic pollen load and the proportion of legitimate pollen decreased with increasing spatial isolation. Legitimate (intermorph) pollen transfer was, however, asymmetric and decreased more rapidly with decreasing proximity to a compatible legitimate mating partner in the S‐morph than in the L‐morph. Total stigmatic pollen loads per flower increased with increasing floral display size, indicating that large plants are disproportionately more visited than smaller individuals. However, because legitimate pollen deposition decreased with increasing floral display size, these results also suggest that larger numbers of flowers increase the degree of geitonogamous pollination. In both the L‐ and S‐morph, seed set significantly decreased with increasing isolation from a legitimate mating partner, but in the L‐morph seed set was less dependent on the spatial distribution of the S‐morph. In addition, seed set significantly increased with floral display size in the L‐morph, but not in the S‐morph. These findings indicate that the spatial distribution of potential mates and variation in floral display size may cause morph‐specific differences in pollen deposition rates and female reproductive success.     

Male siblings inhibit reproductive activity in female pine voles, Microtus pinetorum

Pine vole females paired in breeding cages with male siblings remain unreproductive beyond the age of puberty onset. In this study only 10% of females caged with their brothers reproduced, whereas 85% of females placed with strange males had litters. Mating between a female and a strange male was also suppressed by the presence of a male sibling sequestered behind a wire mesh barrier in the breeding cage. When the sibling male was removed from the cage after 1 day, 78% of the females produced litters. When the sibling remained behind the barrier in the breeding cage, only 42% gave birth to young conceived in his presence. Conception of second litters during the postpartum estrus occurred in over 80% of females caged with strange males alone and only 10% of females caged with sibling males. Female pine voles are induced to become reproductively active by strange males but this activity is depressed by the presence of a brother, and once initiated it does not continue if the female is caged with her brother.     

Spatial distributions of male and female strawberry poison frogs and their relation to female reproductive resources

In many species with a resource-based mating system, males defend resources to increase their attractiveness to females. In the strawberry poison frog, Dendrobates pumilio, suitable tadpole-rearing sites appear to be a limited resource for females. Territorial males have been suggested to defend tadpole-rearing sites to increase their access to females. In this study we investigate the spatial association between tadpole-rearing sites and the sexes as well as the spatial association of males and females. If strawberry poison frogs have resource defense polygyny, we expect males and females to be associated with tadpole-rearing sites and that females will deposit their offspring in tadpole-rearing sites inside the territories of their mates. To test this hypothesis, home range and core area sizes were calculated for both sexes and the association patterns were compared in two areas that differed in their abundance of tadpole-rearing sites. Home ranges and core areas of females were much larger than male home ranges. Females showed a clumped distribution in the vicinity of tadpole-rearing sites. Males were not clumped and were less associated with tadpole-rearing sites. Females generally did not use tadpole-rearing sites in the territory of their mates and we therefore conclude that males did not defend tadpole-rearing sites for females. Our data are consistent with the general assumption that female distribution is influenced by resource distribution and that male distribution depends on female distribution. Nevertheless, the distribution of D. pumilio females was also influenced by male spacing patterns. Males probably initially establish their core areas where female density is high and then females move among territories to sample males. Males compete vigorously for places with high female density, the defense of which is likely important for enhancing their mating success. In general, the spacing patterns did not differ between populations but the sex ratio was strongly female biased in the habitat with more tadpole-rearing sites, reflecting the direct reliance of females on these resources.     

Adenylate cyclase activity in porcine sperm in response to female reproductive tract secretions

Adenylate cyclase activities were studied in porcine sperm in the presence and absence of Mn⁺⁺ before and after incubation in vivo and in vitro. Incubation of sperm in vivo for 30 min increased the Mg⁺⁺-stimulated adenylate cyclase activity from 35.1 pmoles cyclic AMP formed per mg protein per 10 min to 50.4 pmoles. The activity stimulated by Mg⁺⁺ and Mn⁺⁺ increased from 392 to 729 pmoles after 30 min of in vivo incubation. Activity after incubation in vivo for 120 min was not different from activity after 30 min. In vitro incubation of porcine sperm in Ca⁺⁺-free Ringer-fructose resulted in no change, but incubation in oviductal and uterine flushings obtained from gilts soon after ovulation increased Mg⁺⁺-stimulated activity by 24% and Mg⁺⁺?+ Mn⁺⁺-stimulated activity by 49%. In vitro incubations in preovulatory flushings plus follicular fluid or in bovine serum albumin also increased adenylate cyclase activity.