Vitellogenic Follicles Research Articles

Exposure to acetaminophen impairs gametogenesis and fertility in zebrafish (Danio rerio).

Acetaminophen (ACE; paracetamol) is one of the most widely used nonsteroidal anti-inflammatory drugs worldwide and is often found in aquatic systems, where it can act on nontarget species and impair fish reproduction. This study aimed to investigate the effects of chronic exposure to environmentally relevant ACE concentrations (0.5, 5 and 50µg/L) on multiple reproductive parameters in zebrafish (Danio rerio). Gametogenesis was analyzed using histology, morphometry, cell proliferation, and apoptosis. This study also evaluated sex steroids, and prostaglandin E2 (PGE2) levels, gene expression for sex steroids and PGE2 receptors, fertilization rate, and semen quality. In females, exposure to 5 and 50µg/L ACE induced larger and more abundant vitellogenic follicles and increased follicular atresia. In these treatments, males showed a lower proportion and proliferation of undifferentiated spermatogonia and a higher proportion of TUNEL-positive differentiated spermatogonia, spermatids, and spermatozoa, resulting in lower sperm production. ACE increased 17β-estradiol (E2) and reduced 11-ketotestosterone levels in the testis, whereas only E2 increased in the ovaries. In both sexes, gonadal PGE2 levels were reduced. ACE at 50µg/L induced an increase in the gene expression of androgen, estrogen, and PGE2 receptors in the ovaries, and reduced expression in the testes. Results also showed lower egg production and fertilization rate from 28days of exposure with reduced sperm quality. These results demonstrated that ACE impairs the reproductive performance of zebrafish, affecting multiple reproductive parameters, which may be caused by the synergistic action of the imbalance of sex steroids, with a reduction of PGE2 and its receptors.

Reproductive Morphology of the Golden tree snake Chrysopelea ornata (Serpentes: Colubridae) from Ao Nang, Krabi Province, Thailand

We monitored the reproductive morphology of the female and male Golden tree snake, Chrysopelea ornata. The females and males were collected during a year from Ao Nang, Muang Krabi, Krabi province, a southern part of Thailand. We investigated the female and male reproductive systems via anatomical and histological approaches. The results demonstrated that the reproductive tracts of females and males were located above the kidney and its right tract was more anteriorly than the left tract. Ovarian follicles were classified into the previtellogenic, early vitellogenic, and late vitellogenic follicles. Previtellogenic follicles were contained three types of cells in the multi-layered granulosa layer: small, intermediate, and large pyriform cells. This such layer becomes the single layer in which the pyriform cells were disappeared in the vitellogenic follicles. Various stages including corpora lutea, gestation, oviposition, and birth were all observed in this study. The oviductal structure of the Golden tree snake was divided into four regions: anterior and posterior infundibulum, uterus, and vagina. The anterior oviductal wall was covered by ciliated and non-ciliated cuboidal epithelial cells and a thin muscularis layer while its posterior portion was contained by ciliated and non-ciliated cuboidal and columnar epithelial cell, and a thick muscularis layer. We found the tubular ciliated glands in the posterior infundibulum. Additionally, the hypertrophied uterine glands in the uterus were observed during the vitellogenic stage. The seminiferous tubules were active simultaneously with the hypertrophied sexual segment of the kidney.

Waves of follicle development, growth and degeneration in adult ovary of zebrafish (Danio rerio) on chronic exposure to environmental estrogens in laboratory

Patterns of quantitative production of follicles, their growth, and degeneration in the adult ovary of zebrafish (Danio rerio) in response to long-term (80 days) exposure to environmental estrogens (EE) in the laboratory, were studied. Experimentally naive female D. rerio procured from fish farm were acclimated to the laboratory (natural temperature, 26 ± 1° C, photoperiod, 11.30 L:12.30 D) for two weeks and divided into 10 groups. Each group (n = 20) was housed in a separate glass aquarium containing 10 L of conditioned water (physico-chemical parameters maintained within the permissible range prescribed for zebrafish) along with either 5 ng or 10 ng/L of 17α-ethynylestradiol (EE2) or diethylstilbestrol (DES) or bisphenol A (BPA) or estradiol 17-β (positive control) or water with no chemical (negative control). All experimental fish were fed twice daily on commercial pellets (ad libitum) supplemented with Artemia nauplius, the exposure was semi-static and chemical residues in media samples were determined by ultra-performance liquid chromatography (UPLC). Exposure of fish to estrogens increased (p < 0.05) (i) body mass and gonadosomatic indices (GSI) in E2, EE2 and DES groups (ii) previtellogenic and vitellogenic follicles in E2 and EE2 groups (iii) atretic follicles (AF) in DES and BPA groups compared to controls and (iv) decrease in total oocyte volumes (V = 4/3. π. r3) compared to those of E2 group. These results suggest that the chronic exposure of fish to EE (at environmentally relevant concentrations) has a profound influence on ovarian follicular dynamics and the effects of individual EE are discrete on the ovary.

Reproductive biology of the whitespotted eagle ray Aetobatus narinari (Myliobatiformes) captured in the coast of Paraíba and Pernambuco, Brazil.

The present study analysed aspects of reproductive biology based on macroscopic and microscopic structures of whitespotted eagle ray Aetobatus narinari captured by artisanal fishing off the coast of Paraíba and Pernambuco (7° 30'S, 34° 49'W; 7° 47'S, 34° 51'W), northeast Brazil. Of the 71 individuals in the sample, 55% were female (disc width - WD : 532-1698 mm) and 45% were male (WD : 442-1410 mm). The body size at which 50% of the individuals are mature (WD50 ) for males was 1155.8 mm; the clasper length varied between 24 and 184 mm. The WD50 for females was 1293.9 mm; the diameter of the largest vitellogenic follicle varied between 11 and 31 mm; and only the left ovary and uterus were functional. The microanatomy of the reproductive tract of males and females agrees with that of other elasmobranch species. In males, the highest hepato-somatic index (IH ) average and gonado-somatic index (IG ) average occurred in the third bimester of the year, whereas in females the highest values (average IH and IG , respectively) were in the second bimester of the year. Based on the information on reproduction of A. narinari from this study, it will be possible to contribute to the correct management and protection of this species.

Warm and cold temperatures have distinct germline stem cell lineage effects during Drosophila oogenesis.

Despite their medical and economic relevance, it remains largely unknown how suboptimal temperatures affect adult insect reproduction. Here, we report an in-depth analysis of how chronic adult exposure to suboptimal temperatures affects oogenesis using the model insect Drosophila melanogaster. In adult females maintained at 18°C (cold) or 29°C (warm), relative to females at the 25°C control temperature, egg production was reduced through distinct cellular mechanisms. Chronic 18°C exposure improved germline stem cell maintenance, survival of early germline cysts and oocyte quality, but reduced follicle growth with no obvious effect on vitellogenesis. By contrast, in females at 29°C, germline stem cell numbers and follicle growth were similar to those at 25°C, while early germline cyst death and degeneration of vitellogenic follicles were markedly increased and oocyte quality plummeted over time. Finally, we also show that these effects are largely independent of diet, male factors or canonical temperature sensors. These findings are relevant not only to cold-blooded organisms, which have limited thermoregulation, but also potentially to warm-blooded organisms, which are susceptible to hypothermia, heatstroke and fever.

Can the introduction of non-native fish induce variation in life-history traits of a native species in a neotropical lake?

Top predator fish, such as peacock bass (Cichla kelberi) and red-bellied piranha (Pygocentrus nattereri), were introduced in the lacustrine system of the Rio Doce basin and these introductions are associated with loss of aquatic biodiversity. The present work aims to investigate the life-history traits of a native species, thraira (Hoplias malabaricus), in the context of the pressures caused by the introduction of top predator fishes. Two lakes were selected in a conservation unit Doce River State Park (PERD), namely, Lake Carioca, where P. nattereri and C. kelberi were introduced, and Lake Gambazinho, where H. malabaricus occurs in the absence of introduced fish. In total, 146 specimens of H. malabaricus were caught, including 95 in Lake Gambazinho and 51 in Lake Carioca. Significant differences were found in the length–weight relationship (LWR) in the diet, the reproductive period, the vitellogenic follicle size, and the gonadosomatic index (GSI). In the lake with introduced species, thrairas showed allometric growth, a less diversified diet, longer duration of the reproductive period, and high GSI values compared with the control lake. The results indicated that the life-history traits of thrairas can be influenced by the environmental modification caused by the introduction of non-native peacock bass and red-bellied piranha.

High reproductive effort in a vulnerable lizard from high altitudes in Argentina: Reproductive biology and sexual dimorphism in Phymaturus extrilidus.

Reproductive biology is fundamental to understanding the ecology and evolution of lizards which, in turn, is essential for the definition of the species´ conservation status. We studied life-history traits related to the reproduction of the Phymaturus extrilidus lizard, including the male and female reproductive cycles, litter size, mean annual reproductive output, reproductive effort, sexual maturity size and sexual dimorphism, body condition, and fat body cycles. We found sexual dimorphism in size and shape, supporting the hypotheses of sexual and fecundity selection. Females exhibited biennial reproductive cycles synchronous with the annual prenuptial male cycle, adjusted for the maturation of the vitellogenic follicles of females. Females of P. extrilidus have the highest mean annual reproductive output (MARO=1.14) recorded in Phymaturus, and this is accompanied by the highest reproductive effort (C=0.28, C energetic =0.31). Births occur from late summer to early autumn. The female reproductive cycle, strictly biennial, like all species of the P. palluma group, and the vitellogenesis in particular, appear to be limited by body condition and the amount of fat body stored. This study presents the fundamental reproductive traits of P. extrilidus that can provide valuable information to be used in the evaluation of the conservation status of this species.

Melanin-concentrating hormone interferes with the hypothalamic-pituitary-gonad axis in the Mozambique tilapia

This study was conducted to elucidate the influence of melanin-concentrating hormone (MCH) along the reproductive-axis in the female tilapia Oreochromis mossambicus. Administration of MCH (4 μg / 0.1 ml saline) for 22 days resulted in significantly lower gonadosomatic index compared to controls. Significant reduction in the mean numbers of follicles at different stages of development such as previtellogenic (stages I-III), vitellogenic (stage IV) and preovulatory (stage V) follicles was observed in MCH-treated fish compared with controls. On the other hand, the rate of atresia was significantly higher in follicles at stages II, III and IV in MCH-treated fish. In addition, in the pituitary gland, sparsely labelled gonadotropin releasing hormone (GnRH)-immunoreactive fibres were observed in MCH-treated fish in contrast to their intense labelling in controls. The serum level of luteinizing hormone (LH) showed significant decrease, but the serum cortisol level rose significantly following MCH treatment compared to those of controls. Collectively, these results indicate for the first time, that MCH treatment blocks follicular development during the ovarian cycle, possibly through the suppression of GnRH-LH axis in fish. The results also indicate that MCH may activate the stress-axis pathway in fish.

Reproductive Characteristics of the Kulzer’s Rock Lizard Phoenicolacerta kulzeri (Reptilia: Lacertidae)

The present study aims to determine, by histological examination, the female reproductive cycle of specimens of Kulzer’s rock lizards collected in a mountainous region in Lebanon. Females of Phoenicolacerta kulzeri followed a seasonal reproductive pattern. Winter hibernation period lasted for 5 months. Females of P. Kulzeri exhibited a reproductive activity during spring characterized by the presence of vitellogenic follicles in the ovaries and eggs in the oviducts. Oviposition occurred throughout the springtime. Up to two clutches were produced with an average clutch size of 2.9 eggs. Clutch size was significantly correlated to female body size. The attainment of sexual maturity was at a minimum size of 46 mm snout-vent length. The mean body size of adult females was 55.0 mm and did not differ significantly from that of adult males. Females showed a period of sexual rest in summer and none of them showed a reproductive activity in autumn. The female reproductive activity of P. kulzeri was well-synchronized with that of the males in spring; however, an autumnal asynchrony was observed between the female and male reproductive cycles, since males continued to exhibit a spermatogenetic activity.

Kisspeptins stimulate the hypothalamus - pituitary - ovarian axis and induce final oocyte maturation and ovulation in female stinging catfish (Heteropneustes fossilis): Evidence from in vivo and in vitro studies

In the present study, effects of synthetic human Kisspeptin1 (hKiss1) and catfish Kisspeptin2 (cfKiss2) on the hypothalamic - pituitary - ovarian (HPO) axis, and induction of final oocyte maturation and ovulation were investigated in prespawning female stinging catfish (Heteropneustes fossilis) under in vivo and in vitro conditions. Gene expression was quantified by real time quantitative PCR and steroids were measured by specific enzyme-linked immunoassays. Intraperitoneal (ip) injections (1, 2, 3 ng/g body weight, BW) of synthetic hKiss1 and cfKiss2 stimulated hypothalamic, pituitary and ovarian gnrh1 and gnrh2 expression at 24 h and the effect was higher after the cfKiss2 treatment. In vitro incubation of hypothalamus, pituitary and ovary pieces with the Kiss peptides (5, 10, 20 nM) produced a similar effect. GPR54 (Kiss1 receptor) antagonist peptide234, when given ip (5, 10, 20 ng/g BW) or incubated in vitro (5, 10, 20 nM), inhibited the gnrh1 and gnrh2 expression at 24 h. The supplementation with hKiss1 or cfKiss2 restored the inhibition due to peptide234 in vivo and in vitro and the effect was higher in the cfKiss2 combination group. Both hKiss1 and cfKiss2 altered the expression of pituitary gonadotropin (Gth) subunit genes follicle-stimulating hormone β (fshβ), luteinizing hormone β (lhβ) and glycoprotein α (gpα) in vivo and in vitro. The expression of fshβ was more sensitive to the treatments than lhβ expression and the effect was greater in the cfKiss2 groups. Peptide234 in vivo and in vitro inhibited the expression of the Gth genes and the effect was reversed and restored in the hKiss1 and cfKiss2 combination groups. The Kiss peptide treatments in vivo or in vitro stimulated both plasma and ovarian levels of estradiol-17β, progesterone and 17,20β-dihydoxy-4-pregnen-3-one levels. The peptide234 treatment inhibited, or elicited a decreasing trend on the steroid levels both in vivo and in vitro, and the inhibition was reversed by the hKiss1 and cfKiss2 combination treatments. Incubation of post vitellogenic follicles with hKiss1 or cfKiss2 stimulated germinal vesicle breakdown (GVBD) and ovulation. The inhibition due to peptide234 was reversed in the combination groups. Ovulation was not elicited or unaffected in the peptide234 treated groups. The data show that the Kiss peptides act downstream the HPO axis to stimulate oocyte maturation and ovulation, and cfKiss2 peptide is functionally more effective than hKiss1.

Comparative Anatomy of Wild Adult African Catfish (Clarias garIepinus) Ovary During Rainy and Dry Periods in Zaria, Nigeria

The study investigated effects of rainy and dry periods on the ovaries of wild adult Clarias gariepinus in Zaria, kaduna State Nigeria. Twenty-four wild adult catfish with average weight of 1000.00 ± 0.00 gm was used during both periods. They measured a standard body length of 50.17±1.01 cm (rainy) and 44.83 ± 2.09 cm (dry). The fish were sourced from Zaria dam and transported live to Gross Anatomy Laboratory in Ahmadu Bello University Zaria. Each fish was euthanized using tricaine anaesthetic at 8 drops/litre of water. The ovaries were extracted, weighed and fixed in Bouin’s fluid for 24 hours, and processed histologically. Grossly, the ovaries were observed to be well-developed and highly vascularized during rainy period while, regressed and poorly vascular- ized ovaries were seen during dry pe- riod. The mean weight of the ovaries (0.025) and Gonado-somatic index (GSI) value (0.034) were significantly higher during rainy period. Histologically, the ovaries were predominated by vitellogenic and post-vitellogenic follicles during rainy period while, pre-vitellgenic follicles predominates dry periods. The tunica albuginea and interstitial connective tissues were thin during rainy period but thick during dry period. Hence, the result of this study revealed that wild adult catfish spawns during rainy period while, dry period is characterized by low gonadal activities in Zaria, Nigeria.

The effect of α-MSH treatment on the hypothalamic-pituitary-gonad axis in the cichlid fish Oreochromis mossambicus.

In this investigation, we examined the influence of alpha-melanocyte stimulating hormone (α-MSH), a proopiomelanocortin-derived peptide, along the hypothalamic-pituitary-gonad axis in a cichlid fish Oreochromis mossambicus. Administration of α-MSH (40µg/0.1ml saline) for 22days did not affect the number of stage I (previtellogenic) follicles but caused significant reduction in the mean numbers of previtellogenic (stages II and III), vitellogenic (stage IV) and preovulatory (stage V) follicles compared to those of controls. While the gonadosomatic index was significantly lower, the rate of follicular atresia in stages II, III and IV remained significantly higher in α-MSH-treated fish compared to the controls. Furthermore, the mean percent area of gonadotropin-releasing hormone-immunoreactive (GnRH-ir) fibres and luteinizing hormone-immunoreactive (LH-ir) cells were significantly reduced in the proximal pars distalis of the pituitary gland in α-MSH-treated fish compared with the controls. Together, our findings suggest for the first time that the treatment of α-MSH blocks the follicular developmental process during the ovarian cycle, possibly through the inhibition of GnRH-LH pathway in teleosts.

Morphological basis for maternal nutrient provision to embryos in the viviparous fish Ataeniobius toweri (Teleostei: Goodeidae).

In viviparous Mexican fishes of the family Goodeidae, embryos develop in the maternal ovarian lumen. They typically absorb maternal nutrients during gestation by means of "trophotaeniae," that is, specialized, elongated extensions of the hindgut that are exposed to the fluids, which occupy the ovarian lumen. The sole exception is Ataeniobius toweri, whose embryos lack trophotaeniae but are nevertheless matrotrophic. Thus, how its embryos obtain maternal nutrients is unclear. We studied a series of non-pregnant and pregnant ovaries of A. toweri using histology to identify the mechanism of maternal-embryo nutrient transfer. By early-gestation, embryos have depleted their yolk supplies. Yolks are released into the ovarian lumen and are ingested by the developing embryos, as shown by yolk material in their digestive tracts. The embryonic gut is lined by an epithelium consisting of columnar cells with apical microvilli, providing a means for nutrient absorption. Contrary to statements in the literature, embryos develop minuscule trophotaenial rudiments that extend slightly into the ovarian lumen. These structures are formed of an absorptive epithelium that overlies a vascular stroma, similar to the trophotaeniae of other goodeids. Through late gestation, vitellogenic follicles form and oocytes are discharged into the ovarian lumen, contributing to embryonic nutrition. Thus, histological evidence suggests that embryos chiefly obtain nutrients from ingestion of yolk and maternal secretions released into the ovarian lumen. This function possibly is supplemented by uptake via the small hindgut protrusions and other absorptive surfaces (e.g., the skin and the gill epithelium). Our observations are consistent with two evolutionary interpretations of the hindgut protrusions: (a) that they are rudimentary, evolutionary precursors of trophotaeniae formed by exteriorized hindgut; and (b) that they are vestigial remnants of trophotaeniae that were lost during a switch to a form of matrotrophy involving nutrient ingestion.

Effects of Di-Isononyl Phthalate (DiNP) on Follicular Atresia in Zebrafish Ovary.

Di-isononyl phthalate (DiNP) is a plasticizer reported to elicit hormone-like activity and disrupt metabolism and reproduction in fish and other vertebrates. In general, phthalates have been used at high concentrations beyond reported environmental levels to assess their adverse effects on fish gonadal physiology. The present study exposed adult female zebrafish to a wide range of DiNP concentrations [0.42 µg L−1 (10−9 M), 4.2 µg L−1 (10−8 M), and 42 µg L−1 (10−7 M)] for 21 days. We evaluated gene expression profiles related to apoptosis, autophagy, and oxidative stress; DNA fragmentation (TUNEL assay: terminal deoxynucleotidyl transferase dUTP nick end labeling) and caspase activity (CAS3) were also examined. Exposure to 0.42 and 4.2 µg L−1 upregulated the genes coding for tnfa and baxa, sod1, prkaa1, respectively. CAS3 immunohistochemistry revealed a higher number of positive vitellogenic oocytes in ovaries exposed to 0.42 µg L−1. Subsequently, we examined the relationship between CAS3 signaling and DNA fragmentation. Accordingly, DNA fragmentation was observed in vitellogenic follicles of fish exposed to 0.42 and 4.2 μg L−1. Our results demonstrate that follicular atresia can occur after exposure to environmental levels of DiNP for 21 days, which may adversely affect the reproductive performance of female zebrafish in a non-monotonic manner.

Reproductive Phenology of Five Species of Terrestrial Frogs (Genus Eleutherodactylus) from Cuba

We studied the reproductive phenology of five endemic Eleutherodactylus species that coexist in a mountain rainforest in Cuba and estimated their sex ratios at immature and mature stages. We tested the hypothesis that in Neotropical humid sites, reproductive activity in sympatric species will vary in the time of occurrence so that there is no complete temporal overlap. We also investigated whether the length of the breeding season was associated to relative testes size as a proxy for male–male competition. We inferred reproductive phenology from seasonal variation in the number of sexually active individuals, their gonad developmental stage, and male vocal activity from January 2003 to March 2004. Our data do not support the hypothesis of temporal segregation in reproduction for this assemblage because we found a prolonged reproductive pattern in the five species, but there was decreased breeding intensity in the cooler months (November–February). This deduction is supported by a drop in the weight of the ovaries and the number of vitellogenic follicles, absence of mature females or reduction of their abundance, and disappearance of male vocal activity in the winter. We found differences in relative testes size among species, which were not related to differences in the length of the breeding season, but rather to interspecific differences in sex ratio.

Vasopressin Promoter Transgenic and Vasopressin Gene-Edited Ascidian, Ciona intestinalis Type A (Ciona robusta): Innervation, Gene Expression Profiles, and Phenotypes.

Oxytocin (OT) and vasopressin (VP) superfamily neuropeptides are distributed in not only vertebrates but also diverse invertebrates. However, no VPergic innervation of invertebrates has ever been documented. In the ascidian, Ciona intestinalis Type A (Ciona robusta), an OT/VP superfamily peptide was identified, and the Ciona vasopressin (CiVP) induces oocyte maturation and ovulation. In the present study, we characterize the innervation and phenotypes of genetically modified Ciona: CiVP promoter-Venus transgenic and CiVP mutants. CiVP promoter-Venus transgenic Ciona demonstrated that CiVP gene was highly expressed in the cerebral ganglion and several nerves. Fluorescence was also detected in the ovary of young CiVP promoter-Venus transgenic ascidians, suggesting that the CiVP gene is also expressed temporarily in the ovary of young ascidians. Furthermore, a marked decrease of post-vitellogenic (stage III) follicles was observed in the ovary of CiVP mutants, whereas pre-vitellogenic (stage I) and vitellogenic (stage II) follicles were increased in the mutant ovary, compared with that of wildtype Ciona. Gene expression profiles showed that the expression of various genes, including genes related to ovarian follicle growth, was altered in the ovary of CiVP mutants. Altogether, these results indicated that CiVP, mainly as a neuropeptide, plays pivotal roles in diverse biological functions, including growth of early-stage ovarian follicles via regulation of the expression of a wide variety of genes. This is the first report describing a VP gene promoter-transgenic and VP gene-edited invertebrate and also on its gene expression profiles and phenotypes.

Molecular cloning, immunological characterization, and expression analysis of gonadotropin-releasing hormone (GnRH) in the brain of the Chinese alligator during different stages of reproductive cycle.

The neurohormone gonadotropin-releasing hormone (GnRH) plays an essential role in the control of reproductive functions in vertebrates. However, the full-length complementary DNA (cDNA) encoding the GnRHs precursor and it role in the reproductive cycles regulating has not been illustrated in crocodilian species. In the present study, full-length cDNAs encoding GnRH1 forms, its predominant localization within brain and peripheral tissues, and GnRH1 peptide concentrations in the hypothalamus and pituitary in relation to seasonal gonadal development of Chinese alligator were investigated. The cDNA of GnRH1 is consisted of 282bp open reading frame encoding 93 amino acids. The deduced amino acid sequence of alligator GnRH1 contains several conserved regions and shows a closer genetic relationship to the avian species than to other reptile species. The GnRH1 immunopositive cells were not only detected widely in cerebrum, diencephalon, medulla oblongata but also observed in peripheral tissues, these widespread distribution characteristics indicated that GnRH1 possibly possess the multi-functionality in Chinese Alligator. GnRH1 peptide concentration within hypothalamus were observed be the highest in RP group (P<0.05), in association with an peak value in GSI and emerging of late vitellogenic follicles in the ovary. Taken together, our results suggested that GnRH1 was predominantly involved in the vitellogenesis process of seasonal gonadal development of Chinese Alligator.

Differential expression of aquaporin genes during ovary activation in the honeybee Apis mellifera (Hymenoptera: Apidae) queens.

Aquaporins are membrane proteins responsible for the rapid transport of water and solutes through the plasma membrane in almost all organisms including microorganisms, animals and plants. The knowledge about aquaporins in insects has advanced in the last years, especially in organs such as the gut and Malpighian tubules, but their roles in ovaries are poorly understood. This study reports the occurrence and the expression of gene profiles of predicted aquaporins in the ovaries of virgin and mated queens of the honeybee Apis mellifera. The expression of six aquaporin genes (Am-DRIP, Am-PRIP, Am-Eglp1, Am-Eglp2, Am-Eglp3 and Am-BIB) was investigated in the ovaries of queens of different ages and physiological status. The Am-Eglp3 has the higher level of transcript in newly emerged virgin queens. The Am-PRIP and Am-Eglp2 have a higher level of transcripts in 4days-old virgin queens, aged expected to mate. In mated queens, only the Am-Eglp2 show high level of transcripts. Aquaporin was immunolocalized in the follicular cells of both nurse and oocytic chambers of the previtellogenic and vitellogenic follicles. This is the first report for the presence of aquaporins in the ovaries of bees.

Transient opening of tricellular vertices controls paracellular transport through the follicle epithelium during Drosophila oogenesis.

Paracellular permeability is regulated to allow solute transport or cell migration across epithelial or endothelial barriers. However, how cell-cell junction dynamics controls paracellular permeability is poorly understood. Here, we describe patency, a developmentally regulated process in Drosophila oogenesis, during which cell vertices in the follicular epithelium open transiently to allow paracellular transport of yolk proteins for uptake by the oocyte. We show that the sequential removal of E-cadherin, N-cadherin, NCAM/Fasciclin 2, and Sidekick from vertices precedes their basal-to-apical opening, while the subsequent assembly of tricellular occluding junctions marks the termination of patency and seals the paracellular barrier. E-cadherin-based adhesion is required to limit paracellular channel size, whereas stabilized adherens junctions, prolonged NCAM/Fasciclin 2 expression, blocked endocytosis, or increased actomyosin contractility prevent patency. Our findings reveal a key role of cell vertices as gateways controlling paracellular transport and demonstrate that dynamic regulation of adhesion and actomyosin contractility at vertices governs epithelial barrier properties.

Neuropeptide F signaling regulates parasitoid-specific germline development and egg-laying in Drosophila.

Drosophila larvae and pupae are at high risk of parasitoid infection in nature. To circumvent parasitic stress, fruit flies have developed various survival strategies, including cellular and behavioral defenses. We show that adult Drosophila females exposed to the parasitic wasps, Leptopilina boulardi, decrease their total egg-lay by deploying at least two strategies: Retention of fully developed follicles reduces the number of eggs laid, while induction of caspase-mediated apoptosis eliminates the vitellogenic follicles. These reproductive defense strategies require both visual and olfactory cues, but not the MB247-positive mushroom body neuronal function, suggesting a novel mode of sensory integration mediates reduced egg-laying in the presence of a parasitoid. We further show that neuropeptide F (NPF) signaling is necessary for both retaining matured follicles and activating apoptosis in vitellogenic follicles. Whereas previous studies have found that gut-derived NPF controls germ stem cell proliferation, we show that sensory-induced changes in germ cell development specifically require brain-derived NPF signaling, which recruits a subset of NPFR-expressing cell-types that control follicle development and retention. Importantly, we found that reduced egg-lay behavior is specific to parasitic wasps that infect the developing Drosophila larvae, but not the pupae. Our findings demonstrate that female fruit flies use multimodal sensory integration and neuroendocrine signaling via NPF to engage in parasite-specific cellular and behavioral survival strategies.