Female Reproductive Activity Research Articles

Male accessory gland substances from Aedes albopictus affect the locomotor activity of Aedes aegypti females

Dengue is one of the world’s most important mosquito-borne diseases and is usually transmitted by one of two vector species: Aedes aegypti or Aedes albopictus . These two diurnal mosquitoes are frequently found coexisting in similar habitats, enabling interactions between adults, such as cross-mating. The objective of this study was to assess cross-mating between Ae. aegypti females and Ae. albopictus males under artificial conditions and evaluate the locomotor activity of Ae. aegypti virgin females injected with male accessory gland (MAG) homogenates to infer the physiological and behavioural responses to interspecific mating. After seven days of exposure, 3.3-16% of Ae. aegypti females mated with Ae. albopictus males. Virgin Ae. aegypti females injected with conspecific and heterospecific MAGs showed a general decrease in locomotor activity compared to controls and were refractory to mating with conspecific males. The reduction in diurnal locomotor activity induced by injections of conspecific or heterospecific MAGs is consistent with regulation of female reproductive activities by male substances, which are capable of sterilising female Ae. aegypti through satyrisation by Ae. albopictus .

Seasonal Reproduction in the Rock GeckoPhyllopezus pollicarisfrom a Rock Field Habitat in Southeastern Brazil

We studied the reproductive ecology of the gecko Phyllopezus pollicaris in a mountain environment in the Municipality of Diamantina, State of Minas Gerais, Brazil, from February 2005 to January 2006. The reproductive activity of P. pollicaris was cyclic, occurring from the end of the dry season to the end of the wet season. We found no relationship between female reproductive activity and long-term precipitation and temperature. Males exhibited sperm in their testes throughout the year, and their reproductive activity was not related to any of the climatic factors analyzed. Fat storage varied inversely with reproductive activity, and fat-body mass was large in females. All gravid females had a clutch of two eggs.

Progesterone receptor-mediated molecular mechanisms on mam-malian female reproduction

The steroid hormone, progesterone, plays a critical role in regulation of mammalian female reproductive activities. Besides the non-genomic activity of progesterone on target cells, its main physiological effect is caused through genomic action by the ligand-dependent nuclear progesterone receptor. The genomic and non-genomic effects of progesterone collectively mediate various female reproductive functions, including ovulation, embryo implantation, maintenance of pregnancy, initiation of parturition, and development of mammary gland. Although a large number of candidate genes regulated by progesterone have been identified by gene chip technology, the traditional progesterone response elements located in the promoter region of downstream target genes havenot been detected. Accordingly, it was suggested thatthe mechanism of nuclear progesterone receptors regulating transcription may be different from other nuclear steroid receptors. In this review, we summarized the mechanisms of progesterone receptors mediating the physiological effects in various female re-productive activities.

Atypical reproductive cycles in a population of Sceloporus grammicus (Squamata: Phrynosomatidae) from the Mexican Plateau

The spiny lizard Sceloporus grammicus (Squamata: Phrynosomatidae) is a small reptile from central México and the southern United States, occurring in a wide geographic area characterized by extensive variation in topographic and climatic regimes. Genetic variation among lineages from central México is substantial, though the extent to which this variation corresponds with life-history traits remains obscure. To address part of this puzzle, we studied a population of S. grammicus from Tepeapulco, Hidalgo, México. Male-biased sexual dimorphism was extensive in this population; males were larger than females overall, and expressed proportionately larger heads and longer limbs. Minimum size at sexual maturity was similar in the sexes (males: 43 mm; females: 42 mm). In contrast to other populations from the Central Plateau, reproductive activity of males and females was synchronous. Testicular recrudescence of adult males was initiated in October–November, and maximum testis size maintained from December to July. Female reproductive activity showed no clear seasonal pattern: females had vitellogenic follicles from October to July, and pregnant females were found throughout the year. Female body size was not related to litter size. Neither male nor female gonadal mass was correlated with any abiotic environmental variable examined. Differences in reproductive characteristics among populations of S. grammicus might be indicative of plasticity in response to local environmental conditions, local adaptation, or complex gene × environment interactions. We consider these results in the context of previously studied populations of S. grammicus from the Central Plateau and elsewhere, and propose directions for future research.

Climatic correlates of female and male reproductive cycles and plasma steroid hormone levels in the many-lined sun skink Eutropis multifasciata

Gonadal activity and plasma steroid hormone (testosterone and 17β-estradiol) levels in males and females of a viviparous skink (Eutropis multifasciata) were investigated. Changes in the hormone profiles were then correlated to changes in environmental factors such as temperature and rainfall and were found to vary seasonally in both sexes. Gonadal activity, calculated using testicular mass and volume, seminiferous tubule diameter and epithelial height in males and, in females, ovary mass and largest follicular volume also varied seasonally. Peak spermiogenesis was in synchrony with maximal vitellogenic activity, but reproductive synchronicity among females was low. Ovary mass and largest follicular volumes were negatively related to air temperature and rainfall. Testicular mass and volume were not related to air temperature, but both were negatively related to rainfall. Rainfall explained a greater proportion of variation in vitellogenic activity than temperature. As for the climatic correlates of seasonal variation in plasma steroid hormones, we found only in males that the plasma level of testosterone was negatively related to rainfall. Taken together, our data show that male and female reproductive activities are more tightly correlated with rainfall than temperature in E. multifasciata.

Protracted Reproductive Seasonality in the Male Giant Panda (Ailuropoda melanoleuca) Reflected by Patterns in Androgen Profiles, Ejaculate Characteristics, and Selected Behaviors1

The female giant panda (Ailuropoda melanoleuca) experiences a brief (24-72 h) seasonal estrus, occurring once annually in spring (February-May). Our aim was to determine the existence and temporal profile of reproductive seasonality in the male of this species. The study was facilitated by 3 yr of access to eight giant panda males living in a large breeding center in China. Seasonal periods for the male were defined on the basis of female reproductive activity as prebreeding, breeding (early, peak, late), and nonbreeding seasons. Testes size, fecal androgen excretion, ejaculated sperm density, and frequency of reproductive behaviors (i.e., locomotion, scent marking, vocalizations) increased (P < 0.05) from the prebreeding period (October 1-January 31) to the early breeding season (February 1-March 21). Testes volume and sperm concentration were maximal from March 22 through April 15, a period coinciding with maximal female breeding activity. The occurrence of male reproductive behaviors and fecal androgen concentrations began declining during peak breeding and continued from April 16 through May 31 (late breeding period), returning to nadir throughout the nonbreeding interval (June 1-September 30). Reproductive quiescence throughout the latter period was associated with basal testes size/volume and aspermic ejaculates. Our results reveal that testes morphometry, fecal androgen excretion, seminal quality, and certain behaviors integrated together clearly demonstrate reproductive seasonality in the male giant panda. The coordinated increases in testes size, androgen production, sperm density, and sexual behaviors occur over a protracted interval, likely to prepare for and then accommodate a brief, unpredictable female estrus.

Reproduction, Body Size, and Diet of Polychrus acutirostris (Squamata: Polychrotidae) in Two Contrasting Environments in Brazil

We compared reproduction, diet, and body size of Polychrus acutirostris (Squamata: Polychrotidae) from the Cerrado and Caatinga biomes in Brazil. Because these two biomes have widely different climates, we predicted that lizards in Caatinga would produce smaller clutches in response to rainfall unpredictability. We also expected reproductive timing to differ between biomes, with lizards occurring in the Cerrado producing a single clutch in association with the predictable rains of October–November. Contrary to expectations, clutches had fewer (although larger) eggs in Cerrado. Reproductive period was remarkably similar (peak of female reproductive activity in November), but female reproduction started 1 month earlier in Cerrado. Diet composition was also similar, with the exception of spiders, that exhibited a high index of relative importance in Cerrado but were nearly absent in Caatinga lizard diets. Lizards from both biomes ingested a large proportion of plant material, as well as soft-bodied arboreal arthropods, such as orthopterans, and mostly slow-moving, large arboreal insects. Rainfall predictability in the Cerrado therefore did not influence Polychrus reproduction or diet in the same manner as in other lizard species. The large number of small eggs in the Caatinga suggests that the competitive environment for offspring is either unpredictable or that mortality is high but random. Rain forest Polychrus lizards produce few large eggs, suggesting that the competitive environment for offspring is predictably intense and mortality is non-random. Cerrado Polychrus lizards seem intermediate between Caatinga and rain forest Polychrus lizards, producing fewer and larger eggs than their conspecifics in the Caatinga but relatively more and smaller eggs than rain forest Polychrus species.

Effect of Thyroid Disorders on the Adult Female Albino Rats (Histological and Histochemical Study)

The ovary is an endocrine and exocrine gland that plays primary role in female development and reproductive activities. The proper function of the ovary is influenced by other endocrine glands like the thyroid gland, which is one of the most important endocrine glands of the body that affects many cells all over it .This work is designed to focus on the histological and histochemical changes in adult female albino rat`s ovary that happened due to thyroid gland disorders. Forty five adult female albino rats were used in this study. The rats were isolated from male rat for a month before starting the experiment then they are classified into three groups: control group, taken 0.5 ml physiologic saline orally for three months, hypothyroid group, they were taken carbimazol at a dose of 12 mg / kg B.wt. orally for 3 months, hyperthyroid group, they were taken eltroxin at a dose of 100-ug/ kg. B.wt.. Blood samples were taken for assay of serum T3 and T4. Ovaries were fixed in 10% formol saline and paraffin sections were prepared and stained by different stains: Heamatoxylin and Eosin, Periodic acid Schiff`s reaction, Methyl green pyronine and Masson `s trichrome .The result of the control rats showed the well-known histological pictures and histochemical reactions. The hypothyroid group showed an increased ovarian activity as an increase in the surface epithelial cells, excessive amount of collagen fibers, an increase in the amount of CHO materials and in DNA and RNA content. Regarding the hyperthyroid group there was degenerative changes in the ovarian follicles, decrease amount of collagen fibers and decrease in the amount of CHO materials in the ovarian follicles. The association between ovarian diseases and thyroid gland disorders deserves further attention as normal reproductive function needs approximately normal thyroid secretion.

Assessing the effect of persistent organic pollutants on reproductive activity in common dolphins and harbour porpoises

As top predators, marine mammals can provide information on the accumulation of anthropogenic toxins which present the greatest risk to consumers. We assessed the impacts of persistent organic pollutants (POPs) on two cetacean species that feed on commercially important fi sh species in the eastern North Atlantic; the common dolphin (Delphinus delphis) and the harbour porpoise (Phocoena phocoena). In order to evaluate the possible long-term effects of POPs on the continued viability of these populations, we investigated their effects on reproductive activity in females, using ovarian scars as an index of reproductive activity. In harbour porpoises, high POP burdens tended to be associated with lower ovarian scar number, possibly indicating that high contaminant levels were inhibiting ovulation, or some females may go through a number of infertile ovulations prior to a successful pregnancy, birth, and survival of their fi rst offspring during early lactation. In contrast, initial results identifi ed that the common dolphins with contaminant burdens above a threshold level for adverse health effects in marine mammals (17 μg g -1 total PCBs lipid) were resting mature females, with

Sexual dimorphism in the timing of flowering in two dioecious trees in a subtropical wet forest, Puerto Rico

In dioecious plants, sexual selection can promote the evolution of differences in the flowering display of males and females. Theory indicates that male reproductive success is principally limited by the number of mates, while female reproductive success is principally limited by resources invested in fruit production. Consequently, male-male competition may result in earlier and prolonged flowering displays of males, while females should flower later than males and exhibit shorter flowering displays because they need to optimize available resources for fruit production. Here, we report sexual differences in the time of flowering of Cecropia schreberiana and Dacryodes excelsa, two dioecious trees native to Puerto Rico. We interpret our results in the context of sexual selection and potential pollen limitation. Timing of flowering was estimated by direct observations of the trees during flowering and by using flower and seed records of a long-term phenology study. Our results show that males of both species tend to exhibit earlier and more prolonged flowering displays than females. In addition, more than 70% of male and female reproductive activity of both species was prolonged, lasting more than six consecutive months. We propose that prolonged flowering periods working in conjunction with other ecological traits associated with dioecy in plants might help to reduce the effect of pollen limitation on reproductive success.

Reproductive Activity of Three Sympatric Viviparous Lizards at Omiltemi, Guerrero, Sierra Madre del Sur, Mexico

We studied the reproductive characteristics of sympatric populations of Sceloporus formosus scitulus, Sceloporus omiltemanus (Phrynosomatidae), and Mesaspis gadovii (Anguidae) at the Omiltemi forest reserve (Guerrero, Mexico). Males are larger and reach larger body sizes at reproductive maturity and are more colorful than females in both Sceloporus, whereas males are smaller than females and reach sexual maturity at similar body sizes in M. gadovii. These species are single brooded and follow a common pattern of annual reproductive activity. The reproductive activity of females and males of the three species is seasonal; vitellogenesis is initiated in late summer and continues in autumn/rainy season, gestation occurs throughout the winter/dry season, and parturition occurs in early spring. All three species have intersexual synchrony in reproductive activity. In spite of similar reproductive schedules, some subtle features related to the length of each of the reproductive stages could be observed. Sceloporus formosus scitulus has a more extended reproductive season, and large females start vitellogenesis earlier than do small ones. Males have a prolonged reproductive activity and a short nonreproductive season. In contrast, the reproductive cycle of the other two species is defined by shorter reproductive season and less intrasexual asynchrony for both sexes than found in S. f. scitulus. The seasonal pattern of reproduction shared by these three species is characteristic of other viviparous lizards at high elevations in tropical and subtropical latitudes of Central and South America, being convergent for different lizard families. This convergence in reproductive patterns suggests a common evolutionary response to environmental factors associated with montane habitats, whereas specific differences observed within species are attributed to the particular evolutionary history of each taxon.

Sexual selection does not provide an adequate theory of sex differences in aggression

AbstractOur social role/biosocial theory provides a more adequate account of aggression sex differences than does Archer's sexual selection theory. In our theory, these sex differences arise flexibly from sociocultural and ecological forces in interaction with humans' biology, as defined by female and male physical attributes and reproductive activities. Our comments elaborate our theory's explanations for the varied phenomena that Archer presents.

Local adaptation of timing of reproduction: females are in the driver's seat

1. Breeding at the right time of the year is crucial for many temperate zone organisms, as any mismatch with their optimal breeding period leads to a reduction in fitness. The roles of the breeding partners in these adaptive decisions have, however, only rarely been studied. 2. In blue tits (Cyanistes caeruleus) that breed in heterogenous Mediterranean habitats, nearby populations show up to 1-month differences in breeding time. This difference is adaptive as the optimal time for breeding varies by the same amount due to habitat characteristics. But which sex is determining this large difference in timing? 3. We show here that the seasonal development of female reproductive activity (yolk precursor production) closely matches the local optimal breeding time in these two highly contrasted landscapes, while previous studies have demonstrated that male gonadal development does not. In accordance with this, quantitative genetic analyses reveal that timing for breeding is determined by the female only, with no evidence for an additive genetic male effect on laying date. 4. Our results strongly suggest that the adaptive inter-population difference in the laying periods has been driven by females. The central role of females in the determination of breeding period needs to be included when studying how micro-evolutionary processes are affected by global climate change.

Bot fly parasitism of the red-backed vole: host survival, infection risk, and population growth

Parasites can play an important role in the dynamics of host populations, but empirical evidence remains sparse. We investigated the role of bot fly (Cuterebra spp.) parasitism in red-backed voles (Myodes gapperi) by first assessing the impacts of the parasite on the probability of vole survival under stressful conditions as well as on the reproductive activity of females. We then identified the main factors driving both the individual risk of infection and the abundance of bot flies inside red-backed voles. Finally, we evaluated the impacts of bot fly prevalence on the growth rate of vole populations between mid-July and mid-August. Thirty-six populations of red-backed voles were sampled in the boreal forest of Québec, Canada. The presence and the abundance of parasites in voles, two host life history traits (sex and body condition), three indices of habitat complexity (tree basal area, sapling basal area, coarse woody debris volume), and vole abundance were considered in models evaluating the effects of bot flies on host populations. We found that the probability of survival of red-backed voles in live traps decreased with bot fly infection. Both the individual risk of infection and the abundance of bot flies in red-backed voles were driven mainly by vole abundance rather than by the two host life history traits or the three variables of habitat complexity. Parasitism had population consequences: bot fly prevalence was linked to a decrease in short-term growth rate of vole populations over the summer. We found that bot flies have the potential to reduce survival of red-backed voles, an effect that may apply to large portions of populations.

Do conspecific cues affect follicular development in the female leopard gecko (Eublepharis macularius)?

Sexually reproducing organisms must process and respond to internal and external stimuli to successfully synchronize physiological and behavioural processes involved in reproduction. One such cue is an individual's social environment. Interactions with conspecifics affect a female's reproductive activity by inducing, suppressing, and/or accelerating reproductive processes. For example, many studies support the theory that the presence of a same-sex conspecific may suppress an animal's reproductive physiology, whereas an opposite-sex conspecific may stimulate an animal's reproductive physiology. The present study determined whether exposure to a conspecific male or female affects the onset of follicular development in sexually-experienced female leopard geckos ( Eublepharis macularius ). The data show that follicular growth was not affected by whether female geckos were housed next to a male conspecific, a female conspecific, or isolated from conspecifics. In addition, the number of days until the initiation of follicular development of female geckos was not affected by whether the females were housed in the presence of a conspecific or in isolation. The results are discussed within the theoretical framework of the effects of social cues on the reproductive physiology of females and the limited empirical data about such effects in squamate lizards.

Molecular cloning and characterization of estrogen, androgen, and progesterone nuclear receptors from a freshwater turtle (Pseudemys nelsoni).

Steroid hormones are essential for the normal function of many organ systems in vertebrates. Reproductive activity in females and males, such as the differentiation, growth, and maintenance of the reproductive system, requires signaling by the sex steroids. Although extensively studied in mammals and a few fish, amphibians, and bird species, the molecular mechanisms of sex steroid hormone (estrogens, androgens, and progestins) action are poorly understood in reptiles. Here we evaluate hormone receptor ligand interactions in a freshwater turtle, the red-belly slider (Pseudemys nelsoni), after the isolation of cDNAs encoding an estrogen receptor alpha (ERalpha), an androgen receptor (AR), and a progesterone receptor (PR). The full-length red-belly slider turtle (t)ERalpha, tAR, and tPR cDNAs were obtained using 5' and 3' rapid amplification cDNA ends. The deduced amino acid sequences showed high identity to the chicken orthologs (tERalpha, 90%; tAR, 71%; tPR, 71%). Using transient transfection assays of mammalian cells, tERalpha protein displayed estrogen-dependent activation of transcription from an estrogen-responsive element-containing promoter. The other receptor proteins, tAR and tPR, also displayed androgen- or progestin-dependent activation of transcription from androgen- and progestin-responsive murine mammary tumor virus promoters. We further examined the transactivation of tERalpha, tAR and tPR by ligands using a modified GAL4-transactivation system. We found that the GAL4-transactivation system was not suitable for the measurement of tAR and tPR transactivations. This is the first report of the full coding regions of a reptilian AR and PR and the examination of their transactivation by steroid hormones.

Fatores genéticos e ambientais sobre a probabilidade de prenhez precoce em bovinos Caracu

Em bovinos, critérios de seleção, associados à precocidade sexual, vêm sendo atualmente pesquisados para a sua inclusão em programas de seleção, visando à diminuição da idade de entrada dos animais em reprodução, com conseqüências positivas sobre a receita do rebanho. O objetivo deste trabalho foi estimar a herdabilidade da probabilidade de prenhez precoce (PPP) de fêmeas Caracu, característica associada à puberdade e que pode ser considerada como indicadora do início da atividade reprodutiva, usando para isso, um arquivo com 5.273 observações. A significância dos efeitos da produção de leite da mãe na primeira lactação, da idade da mãe ao parto e da idade à desmama das novilhas sobre a PPP, foi analisada por meio do procedimento logístico de regressão. Empregou-se a análise Bayesiana para a estimação de herdabilidade da PPP mediante um modelo de touro, onde foram incluídos os efeitos de grupo de contemporâneos, produção de leite na primeira lactação, touro e resíduo. A média a posteriori da herdabilidade da PPP foi de 0,13, que, embora baixa, evidenciou a presença de ação gênica aditiva na determinação desta característica, o que possibilitaria a obtenção de progresso genético na mesma.

ASPECTOS CITOPATOLÓGICOS DA MUCOSA VAGINAL DE CAMUNDONGAS TRATADAS COM PROGESTERONA

The domestic mammal’s estrus cycle regulation is a complex process, controlled by hypothalamus-adenohy¬pofisis-ovary axis, through endocrine and neuroendocrine mechanisms. The use of progesterone hormone is an im¬portant way to regulate the functional and structural female reproductive tract activity. Considering the frequent pro¬gesterone usage and its importance, we intended to study the vagina citopathologycal aspects of female mice treated with progesterone. We used thirty six Swiss Webster female mice. These animals were divided in four groups: S Group (control group- female mice treated with vehicle and valued during fifteen days), Groups E1, E2 e E3 (Experimental groups - female mice treated with 0,375 mg, 0,75 mg and 1,5 mg of medroxiprogesterone acetate and valued during fifteen days). Based on our results, we can conclude that medroxiproges¬terone acetate at once dose at 0,75 mg or 1,5 mg induces to estrus cycle interruption an induces to an increasing number of leucocytes observed at vaginal cytological exam. KEY-WORDS: Colpocytology, estral cycle, interruption of estrus cycle, medroxiprogesterone.

Progesterone Receptors in the Developing Genital Tubercle: Implications for the Endocrine Disruptor Hypothesis as the Etiology of Hypospadias

In fetal mice genital tubercles the ontogenetic expression of progesterone receptors and the effect of in utero estrogen and testosterone exposure were investigated. To evaluate ontogenetic progesterone receptor expression genital tubercles from untreated fetuses at gestational days 12, 14, 16 and 18, and newborn pups were prepared for real-time reverse transcriptase-polymerase chain reaction or immunohistochemistry. To evaluate estrogen and testosterone effects pregnant dams were gavaged once daily with corn oil (vehicle), ethinyl estradiol or testosterone propionate from gestational days 12 through 17. At gestational day 19 the genital tubercles of delivered fetuses were harvested for morphological examination and then pooled for real-time reverse transcriptase-polymerase chain reaction. Progesterone receptor protein was first detected at gestational day 12 in the urethral plate and mesenchyma. At later stages staining intensity increased with a greater progesterone receptor signal, especially in the urethra. Progesterone receptor mRNA expression showed different increasing patterns in each sex until birth. However, no difference was noted between male and female genital tubercles in terms of the distribution and quantity of progesterone receptor expression. In utero ethinyl estradiol led to 8.2, 9.7 and 5.2-fold increases in progesterone receptor mRNA in females and in males with and without hypospadias, respectively. Testosterone propionate significantly decreased progesterone receptor mRNA levels in females and males. Progesterone receptors are expressed in developing genital tubercles, suggesting a direct role of progesterone in normal genital tubercle patterning. Their increasing expression until birth also implies increasing sensitivity of the genital tubercles to the effects of estrogenic and progestogenic endocrine disruptors during fetal life. Ethinyl estradiol and testosterone propionate lead to opposing effects on progesterone receptor expression, in addition to their opposing morphological effects on the genital tubercles. These findings expand our knowledge of genital tubercle morphogenesis and provide important information for understanding the effects of endocrine disruptors.

Reproductive cycle of the blacknose shark Carcharhinus acronotus in the Gulf of Mexico

The reproductive periodicity of blacknose sharks Carcharhinus acronotus in the northern Gulf of Mexico was determined by examining reproductive tissues from specimens collected monthly from 2002 to 2005. Monthly changes in shell gland mass, right ovary mass and ovarian follicle diameter were assessed for 74 mature females. Temporal changes in testes mass, testes width and proportion of mature spermatocysts were examined for 64 mature males. Trends in female reproductive tissues suggested an annual peak in reproductive activity during June and July, while trends in male variables suggested an annual reproductive peak during May and June. Although male and female reproductive activity peaked in different months, a strong synchronicity existed between the proportion of mature spermatocysts and the diameter of the largest ovarian follicle. Based on these results, the mating season of blacknose sharks lasts from mid‐May to July in the Gulf of Mexico. Maximum embryo sizes were observed in May, which suggested that partition occurs during late May or early June. Results indicate that blacknose sharks have a clearly defined annual cycle in the Gulf of Mexico. This conclusion is further supported by the complete absence of gravid females without vitellogenic ovarian follicles among all mature females examined.