Reproduction in the piranha Serrasalmus spilopleura, a neotropical fish with an unusual pattern of sexual maturity

Synopsis Reproduction in female Serrasalmus spilopleura (Characiformes, Characidae) from the Itumbiara reservoir (18°28 S, 48°36 W), Paranaíba River, Brazil, was examined with emphasis on the relationship between condition factors and coelomic fat, the annual reproductive cycle and the unusual dynamics of its sexual maturity. The condition factor and coelomic fat index follow a similar pattern along the stages of reproductive cycle. Variations in the condition factor along the reproductive cycle were assigned to variations in the fat contents of the carcass. Serrasalmus spilopleura exhibits characteristics of partial spawning fish and reproduces throughout the year. Sexual maturity occurs at 17.8 cm standard length. Resting and totally spent females were not captured. Females cycle from partially spent to intermediate/advanced maturation without going into the totally spent or resting stages. The initial maturation stage is restricted to fish of intermediate size. Once the initial maturation stage has started the fish remains there for a considerable period of its lifetime before entering in the intermediate maturation stage, an uncommon sexual maturity pattern. The long duration of the initial maturation stage was responsible for the females not returning to the resting stage after spawning.     

Reproductive potential and output of the Bahama Parrot Amazona leucocephala bahamensis

We evaluated reproductive investment and loss in the endangered Bahama Parrot Amazona leucocephala bahamensis using a fitness components model that corresponds to stages of the reproductive cycle. On average, a pair produced 3.6 eggs but fledged only 0.8 young, a 77% loss on their initial investment. While losses accrued throughout the cycle, they were highest during the hatching and post-hatching stages. Partial hatching failure and total brood failure, respectively, were the primary sources of loss at these stages. These components did not change significantly over the four years of the study. Total nesting failure changed significantly over time and exacerbated losses during the incubation stage in two of the four years of the study. The implementation of a conservation management plan that would reduce total nest and brood failures is urgently needed.     

Composition and Content of Fatty Acids in the Tissues of Males and Females of Eurasian Perch <Emphasis Type="Italic">Perca fluviatilis</Emphasis> at the Late Stages of Reproductive Cycle

We have studied the composition and content of fatty acids (FAs) in the muscle, liver, and reproductive tissues of male and female of Eurasian perch from the Krasnoyarsk water reservoir at the late stages of reproductive cycle. The dynamics of FA composition of the muscle tissue correlates with seasonal changes in food-source composition, while the FA composition of the liver and gonad is influenced by the reproductive cycle and differs between males and females. Multivariate analysis shows that the redistribution of FAs at different stages of the reproductive cycle involves mainly the gonads and liver tissue. The nutritive value of the muscle tissue of perch, as a source of long-chain polyunsaturated FAs, does not depend on the reproductive stage.     

Oviductal cell proteome alterations during the reproductive cycle in pigs

The mammalian oviduct plays a crucial role in events leading to the establishment of pregnancy. During the reproductive cycle, the reproductive system undergoes various changes, including alterations in the number of different cell types in the oviductal epithelium and changes in the height of oviductal cells. Maintaining the unique oviductal environment required for the fertilization and early embryonic development comes with an energy cost to the organism. Therefore, it is hypothesized that structural and functional changes to the oviduct during the reproductive cycle represent vital preparations for the development of suitable environments for conception and embryo support. Here, we aimed to identify the changes in protein expression profile that occur during the follicular and luteal stages of the reproductive cycle in oviductal epithelial cells. The porcine oviductal epithelial cell proteomes from the follicular and luteal stages of the reproductive cycle were contrasted after separation by 2-D gel electrophoresis. Several oviductal epithelial cell proteins were up- or down-regulated during the reproductive cycle. We checked the quantitative changes of two of these molecules during different stages of the reproductive cycle using Western blot analysis. Finally, a number of these proteins were identified using tandem mass spectrometry. The results demonstrated distinctive differences in the proteomic profiles of the oviduct between follicular and luteal phases of the reproductive cycle.     

Performing Vaginal Lavage,Crystal Violet Staining,and Vaginal Cytological Evaluation for Mouse Estrous Cycle Staging Identification

A rapid means of assessing reproductive status in rodents is useful not only in the study of reproductive dysfunction but is also required for the production of new mouse models of disease and investigations into the hormonal regulation of tissue degeneration (or regeneration) following pathological challenge. The murine reproductive (or estrous) cycle is divided into 4 stages: proestrus, estrus, metestrus, and diestrus. Defined fluctuations in circulating levels of the ovarian steroids 17-β-estradiol and progesterone, the gonadotropins luteinizing and follicle stimulating hormones, and the luteotropic hormone prolactin signal transition through these reproductive stages. Changes in cell typology within the murine vaginal canal reflect these underlying endocrine events. Daily assessment of the relative ratio of nucleated epithelial cells, cornified squamous epithelial cells, and leukocytes present in vaginal smears can be used to identify murine estrous stages. The degree of invasiveness, however, employed in collecting these samples can alter reproductive status and elicit an inflammatory response that can confound cytological assessment of smears. Here, we describe a simple, non-invasive protocol that can be used to determine the stage of the estrous cycle of a female mouse without altering her reproductive cycle. We detail how to differentiate between the four stages of the estrous cycle by collection and analysis of predominant cell typology in vaginal smears and we show how these changes can be interpreted with respect to endocrine status.     

Seasonal changes in thyroid activity in the female sheath-tailed bat,Taphozous longimanus (Chiroptera: Emballonuridae)

The present study was designed to investigate changes in thyroid activity during the reproductive cycle in Taphozous longimanus. Thyroid gland showed marked seasonal variation in weight and secretory activity. It was inactive in quiescence and early to mid-winter dormancy and active during recrudescence and breeding period during late winter dormancy. The serum 3,5,3'-triiodothyronine (T3) and thyroxine (T4) concentrations showed significant variation and closely coincided with thyroid activity. The T3 and T4 concentrations were higher in recrudescence, late winter dormancy and minimum in quiescence and initial stages of first pregnancy. The body weight (r = 0.56), ovary weight (r = 0.73), and thyroid weight (r = 0.70) showed correlation with each other and with T3 and T4 concentrations. The correlation between body weight, thyroid weight and T3 and T4 concentrations in non-pregnant bats was higher when compared with pregnant bats. The T3 and T4 levels remained low during the initial stages of development in first pregnancy when compared with the initial stages of second pregnancy. The scant food supply and low levels of T3 and T4 and low temperature during initial stages of first pregnancy might be responsible for differential rate of fetal development in two successive pregnancies in T. longimanus.     

Canine herpesvirus-1 (CHV-1): clinical, serological and virological patterns in breeding colonies

Canine herpesvirus-1 (CHV-1) is presumed to be enzootic in the dog population and is associated with reproductive disorders and neonatal mortality. To advise dog breeders towards an effective management of CHV-1 infected colonies, 27 breeding bitches were studied during one reproductive cycle in field conditions: the effect of cycle stage, kennel size, initial antibody titre, mating and gestation on serologic and viral excretion patterns was evaluated, while the association between reproductive disorders and CHV-1 antibody titres and viral excretion was also analysed. All initially seronegative bitches seroconverted, while 40% of the initially seropositive bitches became seronegative at one or two occasions. No difference in antibody patterns was observed between mated and unmated bitches. Of the mated bitches, 46% experienced infertility, foetal resorption or mummification. No difference in antibody patterns was observed depending on the occurrence of reproductive disorders even if a decrease in antibody titres during early or late-di-oestrus was often present. Significantly higher titres were observed at all cycle stages in large kennels. None of the vaginal and nasal samples or buffy coats tested positive for CHV-1 DNA. The mixed image of clinical and sub-clinical carriage in this study demonstrated CHV-1 has a complex and difficult to predict clinical behavior. Preventive management with vaccination of reproducing bitches in kennels with reproductive disorders should therefore be advised.     

Reproductive dynamics of the white shrimp Litopenaeus schmitti (Burkenroad 1936) in a beach seine fishery in northeastern Brazil

The aim of the present study was to investigate the reproductive dynamics of the Litopenaeus schmitti through macroscopic and microscopic analyses. Specimens were collected monthly from December 2016 to November 2017 through artisanal beach seine fishery in the municipality of Lucena, state of Paraíba, Brazil. A total of 1710 shrimp were caught and the proportion of males was significantly lower than that of females (43.51% and 56.49%). The ovarian maturation stages were classified as immature, initial development, advanced development, mature and spent. These classification criteria added an additional stage than those previously reported for this species on the Brazilian coast. The proportion of ovarian maturation stages per month suggest a seasonal reproductive cycle that extends from September to June, with no reproductive activity occurring in July and August. The reproductive activity was directly related to the precipitation and salinity in the area of the present study. Mean cephalothorax length at first gonad maturity for females (2.20 cm) was larger than values reported 13 years ago for this species in the same area. This finding may indicate that the prohibition of motorized trawler fishing in the area since 1990 is contributing to the more sustainable exploitation of this resource.     

[125I] gonadotropin binding to the ovary of an Indian major carp,Catla catla,at different stages of reproductive cycle

At different stages of the annual reproductive cycle ofCatla catla, a major Indian carp, specific binding of gonadotropic hormone to the plasma membrane receptors was demonstrated. Maximum specific binding of [¹²⁵I]Catla gonadotropic hormone was obtained at 30‡C and pH 7.5 during 2 h of incubation.Catla gonadotropic hormone binding was saturable with high affinity. Competitive inhibition experiment showed that binding site was specifically occupied by piscine gonadotropic hormone,Catla gonadotropic hormone and murrel gonadotropic hormone, human chorionic gonadotropin was a weak competitor while bovine thyroid stimulating hormone, bovine prolactin and ovine follicle stimulating hormone had no effect. Scatchard analysis ofCatla gonadotropic hormone binding to the plasma membrane preparation from the carp oocytes of different reproductive stages showed that the range of dissociation constant(K _d ) varied from 0.78 to 0.97 x 10^-10 M. However, maximum binding capacity (B-max) varied remarkably between the different stages of reproductive cycle, it was 6.11 ± 0.36 fmol/mg protein in the preparatory stage which increased to about three-fold in prespawning stage of reproductive cycle (17.0 ± 0.29 fmol/mg protein) and spawning (18.7 ± 0.17 fmol/mg protein) and lowest in postspawning stage of reproductive cycle (5.28 ± 0.28 fmol/mg protein). Fluctuation in the number of gonadotropic hormone binding site at different stages of annual reproductive cycle was found to be coincided well with the pattern of ovarian steroidogenesis in response toCatla gonadotropic hormone as determined by the formation of progesterone from pregnenolone.     

In vitro maturation,fertilization and development of domestic cat oocytes recovered from ovaries collected at three stages of the reproductive cycle

This study was conducted to examine the effect of the donor cat's reproductive cycle stage on in vitro maturation (IVM), in vitro fertilization (IVF), and in vitro development of oocytes recovered from ovaries that were collected and stored at 35 degrees C for a short period (1-6 h). Based on the presence or absence of follicles and corpora lutea, the ovarian pairs collected were classified into inactive, follicular, or luteal stages. Nuclear status of 161 cumulus-oocyte complexes (COCs) were examined immediately after recovery; 91.3% of the oocytes were found to be at the immature germinal vesicle (GV) stage, and 3.7% of the oocytes were at metaphase II (MII) stage. The percentage of the oocytes at the GV stage was significantly lower in the follicular stage than in the inactive stage (P < 0.01). Of the oocytes from the follicular stage, 9.1% were at MII stage. After culture for 24 h, however, the proportions of oocytes that reached metaphase I and MII were not different among the reproductive cycle stages of the ovaries collected (P > 0.05). After co-incubation with sperm, 63.1% of oocytes were fertilized, but there were no significant differences among the reproductive cycle stages of the ovaries with respect to the proportions of normal and polyspermic fertilization. However, the number of oocytes reaching cleavage stage and development to the morula and blastocyst stages from follicular stage ovaries were significantly lower (P < 0.05) than those obtained from inactive and luteal stage ovaries. These results indicate that the reproductive cycle stage of donor cat ovaries, stored at 35 degrees C, has no apparent effects on the frequencies of maturation and fertilization of oocytes, but influences developmental competence of the oocytes following IVM or IVF.     

Reproductive cycle of <Emphasis Type="Italic">Antedon mediterranea</Emphasis> (Crinoidea,Echinodermata): correlation between morphology and physiology

Gonads of the mediterranean crinoid Antedon mediterranea were analyzed in order to reconstruct their histological organization. The tissue arrangement resembled that previously described in other crinoids. Five reproductive stages were identified in both males and females: recovery, growing, premature, mature, spent. Sexually dimorphic characters were observed at the gonopore level. Hermaphroditic individuals were never detected. There were novel findings concerning somatic accessory cells of the gonads. The reproductive cycle periodicity was indicated by analysis of reproductive stage frequencies in the period 2003–2005: spring and winter were the seasons with highest and lowest maturity levels, respectively. A role in the regulation of reproduction was hypothesized for testosterone and 17β-estradiol, which were found to be present in A. mediterranea tissues and to vary during the reproductive cycle, thus suggesting a correlation between steroid levels and morphologically recognizable reproductive stages.     

Distribution and Regulation of ENaC Subunit and CFTR mRNA Expression in Murine Female Reproductive Tract

The present study investigated the regional distribution and cyclic changes in the mRNA expression of epithelial Na+ channel (ENaC) subunit and cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated Cl- channel, in adult female mouse reproductive tract. In situ hybridization revealed that in contrast to the abundant expression of CFTR, ENaC (alpha, beta, gamma) mRNA signal was not detected throughout the estrus cycle in the ovary and oviduct. Messenger RNA for all ENaC subunits was abundantly detected in the cervical and vaginal epithelia throughout the estrus cycle but for CFTR, mRNA was found only at proestrus. In the uterine epithelium, alphaENaC mRNA was detected at diestrus but not found at any other stage, while CFTR mRNA was only detected at early estrus but not other stages. Semi-quantitative RT-PCR detected mRNA for all ENaC subunits in the uterus throughout the cycle with maximal expression at diestrus and CFTR mRNA was only found in the early stages of the cycle. The involvement of ENaC and CFTR in Na+ absorption and Cl- secretion was demonstrated in cultured endometrial epithelia using the short-circuit current technique and found to be influenced by ovarian hormones. Taken together, these data indicate a main secretory role of the ovary and oviduct and a predominantly absorptive role of the cervix and vagina. The present results also suggest an ability of the uterus to secrete and absorb at different stages of the estrus cycle. Variations in the fluid profiles may be dictated by the regional and cyclic variations in expression of ENaC and CFTR and are likely to contribute to various reproductive events in different regions of the female reproductive tract.     

Density dependence in the terrestrial life history stage of two anurans

Populations of species with complex life cycles have the potential to be regulated at multiple life history stages. However, research tends to focus on single stage density-dependence, which can lead to inaccurate conclusions about population regulation and subsequently hinder conservation efforts. In amphibians, many studies have demonstrated strong effects of larval density and have often assumed that populations are regulated at this life history stage. However, studies examining density regulation in the terrestrial stages are rare, and the functional relationships between terrestrial density and vital rates in amphibians are unknown. We determined the effects of population density on survival, growth and reproductive development in the terrestrial stage of two amphibians by raising juvenile wood frogs (Rana sylvatica) and American toads (Bufo americanus) at six densities in terrestrial enclosures. Density had strong negative effects on survival, growth and reproductive development in both species. We fitted a priori recruitment functions to describe the relationship between initial density and the density of survivors after one year, and determined the functional relationship between initial density and mass after one year. Animals raised at the lowest densities experienced growth and survival rates that were over twice as great as those raised at the highest density. All female wood frogs in the lowest density treatment showed signs of reproductive development, compared to only 6% in the highest density treatment. Female American toads reached minimum reproductive size only at low densities, and male wood frogs and American toads reached maturity only in the three lowest density treatments. Our results demonstrate that in the complex life cycle of amphibians, density in the terrestrial stage can reduce growth, survival and reproductive development and may play an important role in amphibian population regulation. We discuss the implications of these results for population regulation in complex life cycles and for amphibian conservation.     

Development of the sexual skin with pubertal maturation in female chimpanzees

We examined the adolescent development of the sexual skin of chimpanzees (Pan troglodytes) by daily observation, evaluation of swelling, and weekly photogrametry. Although the size of swelling differed with the individual, the development of sexual swelling followed four stages: (1) initial stage, the labial region began to show a slight swelling and recovery; (2) labial stage, swelling at the labial region became maximal; (3) anal stage, another swelling center appeared in the anal region and enlarged; and (4) full maturity stage, the labial and anal regions merged into a full swelling. Menarche occurred after the beginning of the anal stage, and the regular cycle was then established. All of the swelling stages and the peak swelling size are regarded as good indicators of reproductive maturation in chimpanzees.     

Cervico-Vaginal Immunoglobulin G Levels Increase Post-Ovulation Independently of Neutrophils

The prevalence of sexually transmitted infections (STIs) is often higher in females than in males. Although the reproductive cycle profoundly modulates local immunity in the female reproductive tract (FRT) system, significant gaps in our knowledge of the immunobiology of the FRT still exist. An intriguing and frequently observed characteristic of the FRT is the predominant presence of immunoglobulin (Ig) G in cervico-vaginal secretions. We show here that in the mouse, IgG accumulation was enhanced approximately 5-fold post-ovulation, and was accompanied by an influx of neutrophils into the FRT. To determine whether these two events were causally related, we performed short-term neutrophil depletion experiments at individual stages throughout the estrous cycle. Our results demonstrate that neutrophils were not necessary for cycle-dependent tissue remodeling and cycle progression and that cycle-dependent IgG accumulation occurred independent of neutrophils. We thus conclude that neutrophil influx and IgG accumulation are independent events that occur in the FRT during the reproductive cycle.     

On nitric oxide signaling,metamorphosis, and the evolution of biphasic life cycles

Summary Complex life cycles are ancient and widely distributed, particularly so in the marine environment. Generally, the marine biphasic life cycle consists of pre‐reproductive stages that exist in the plankton for various periods of time before settling and transforming into a benthic reproductive stage. Pre‐reproductive stages are frequently phenotypically distinct from the reproductive stage, and the life cycle transition (metamorphosis) linking the larval and juvenile stages varies in extent of change but is usually rapid. Selection of suitable adult sites apparently involves the capacity to retain the larval state after metamorphic competence is reached. Thus two perennial and related questions arise: How are environmentally dependent rapid transitions between two differentiated functional life history stages regulated (a physiological issue) and how does biphasy arise (a developmental issue)? Two species of solitary ascidian, a sea urchin and a gastropod, share a nitric oxide (NO)‐dependent signaling pathway as a repressive regulator of metamorphosis. NO also regulates life history transitions among several simple eukaryotes. We review the unique properties of inhibitory NO signaling and propose that (a) NO is an ancient and widely used regulator of biphasic life histories, (b) the evolution of biphasy in the metazoa involved repression of juvenile development, (c) functional reasons why NO‐based signaling is well suited as an inhibitory regulator of metamorphosis after competence is reached, and (d) signaling pathways that regulate metamorphosis of extant marine animals may have participated in the evolution of larvae.     

Histochemical detection of steroid synthesizing cells in the testes of goldfish,Carassius auratus,during the annual reproductive cycle

We investigated the sites of Δ⁵-3β-hydroxysteroid dehydrogenase (3 β-HSD) and glucose-6-phosphate dehydrogenase (G-6-PD) synthesis in the testes of goldfish, Carassius auratus, during the annual reproductive cycle. The histochemistry of fish gonads has been investigated previously in many species other than goldfish. The reproductive cycle of goldfish, is divided into five stages and the steroid synthesizing cells of the testes were studied during these stages, using histochemical techniques. We found that interstitial cells and seminiferous tubules are the main steroid synthesizing sites in testes of goldfish, and that enzyme activity was more intense in the interstitial cells than in the seminiferous tubules. During the pre-spawning months, 3 β-HSD and G-6-PD activities were weak compared to the spawning months.     

高氏后异刺线虫肠道和生殖细胞超微结构观察

我们曾经发现雌性高氏后异刺线虫在生殖周期中,虫体的外表形态和器官结构以及细胞核内DNA含量均发生连续的变化。现在进一步对线虫细胞的超微结构进行分析,着重观察核内染色质结构的变化。前三期雌虫肠细胞核内有许多粗大的染色质团块和显著的核仁。Ⅳ期肠核内染色质团块融合成少数球体,而且不断减少,以致消失,单剩下染色质细粒(纤丝切面)。而核仁增大,结构更为复杂。卵巢细胞亦有类似改变,但末见染色质球体。雄虫并无生殖周期,也无上述变化。