Influence of Docosahexaenoic and Eicosapentaenoic Acid Ratio and Temperature on the Growth Performance, Fatty Acid Profile, and Liver Morphology of Dusky Grouper (Epinephelus marginatus) (Teleostei: Serranidae) Juveniles.

An 8-week trial was performed to evaluate the influence of docosahexaenoic (DHA) and eicosapentaenoic acid (EPA) ratios and temperature on the fatty acid (FA) metabolism and liver morphology of Epinephelus marginatus. A basal diet was manufactured, and DHA (D1:0.5%; D2:0.75%; D3:1%; and D4:1.5%) and EPA (D1:1.0%; D2:0.75%; D3:0.5%; and D4:0%) levels were added. E. marginatus were kept in twelve tanks with a lower temperature (LT, 23.17 ± 0.12 °C) and twelve with a higher temperature (HT, 28.63 ± 0.06 °C). The DHA/EPA ratio did not affect performance, regardless of the temperature, but the animals fed with the D4 diet showed better growth at HT. A higher lipid deposition and a large lipid vacuole area in the hepatocytes at HT were observed, regardless of the diet. Triacylglycerol (TG) in reflected the diet FA profile mainly in the muscle and liver, whereas the phospholipid (PL) was less influenced by the diet. The same DHA content in the TG fraction of muscle (D3 and D4) were observed at LT; however, only the DHA/EPA ratio of D4 could be differentially stored in the TG fraction of muscle (HT). Monounsaturated and polyunsaturated FA increased in the PL of the eyes at HT, whereas saturated FA was reduced in the TG and PL fractions at LT. These results evidence the importance of temperature and a balanced DHA/EPA ratio in the diet of marine fish.

Post-feeding Molecular Responses of Cobia (Rachycentron canadum): RNA-Sequencing as a Tool to Evaluate Postprandial Effects in Hepatic Lipid Metabolism.

We used transcriptome sequencing to investigate the hepatic postprandial responses of Rachycentron canadum (cobia), an important commercial fish species. In total, 150 cobia juveniles (50 per tank, triplicate) were fed ad libitum with a commercial diet for 7 days, fasted for 24 h, and fed for 10 min. The liver was sampled 10 min prior to feeding and 30 min, 1, 2, 4, 8, 12, and 24 h after the feeding event. Each sample was evaluated in terms of liver fatty acid profile and gene expression. Differential gene expressions were evaluated, focusing on fatty acid synthesis and oxidation pathways. In general, the liver fatty acid profile reflected diet composition. Docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) levels increased at 8 to 12 h but decreased at 24 h after the feeding event. A high number of differentially expressed genes (DEGs) were observed comparing fish that fasted for 8 h with those fasted for 30 min and 24 h, while a reduced number of DEGs was observed comparing individuals who fasted for 30 min compared with those who fasted for 24 h. Similarly, the main differences in the expression of genes related to the fatty acid biosynthesis and oxidation pathways were noticed in individuals who fasted for 8 h compared with those who fasted for 30 min and 24 h. The results suggested that the adequate time to sample the individuals ranged between 8 and 12 h after the meal since, apparently, after 24 h, differential gene expression was not necessarily influenced by food intake.

Dynamics of ovarian maturation during the annual reproductive cycle of the endangered fish Steindachneridion parahybae (Siluriformes: Pimelodidae) in captivity.

To characterize the female reproductive biology of the endangered species Steindachneridion parahybae in captivity, the authors used the concentration of gonadal steroids and the oocyte development during the annual reproductive cycle (RC) and after artificial induced spawning (AIS) until 48 h. Three stages of gonadal maturation were identified, based on morphological and physiological features: early maturation or previtellogenic (PRV) oocyte, advanced maturation or vitellogenic (VTG) oocyte and regression (REG) or follicular atresia. They identified and characterized the following stages of germ cells: oogonia, perinucleolar and cortical alveoli, and VTG and atretic oocytes during RC. The oestradiol levels were higher in PRV than those in VTG and REG during the RC, whereas androgens showed higher levels of oestradiol in VTG than those in PRV and REG. The progestogen levels remained unchanged during the whole RC. The final oocyte maturation (FOM) was achieved after AIS and postovulatory follicles (POF) were identified. Plasma concentration of progestogens (17α,20ß-dihydroxy-pregnen-3-one and 17α-hydroxyprogesterone) increased considerably after AIS, remaining high up to 6 h after AIS, and progressively decreased over time after AIS. During RC, the lack of FOM and POFs reveals that captivity negatively impacts S. parahybae reproduction. Nonetheless, the VTG stage of oocytes, reached during RC, is suitable for ovulation induction with artificial hormone manipulation, enabling the reproduction of this species in captivity and being essential for the success of fish farming and/or fish conservation programmes (conservationist aquaculture).

Long-Chain Polyunsaturated Fatty Acids n-3 (n-3 LC-PUFA) as Phospholipids or Triglycerides Influence on Epinephelus marginatus Juvenile Fatty Acid Profile and Liver Morphophysiology.

Phospholipids (PL) are membrane components composed of fatty acids (FA), while triglycerides (TG) are a main source of energy and essential FA. Polyunsaturated FA (PUFA), such as docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), are essential for marine carnivorous fish; thus, an 8-week experiment was performed to evaluate the influence of DHA and EPA, provided as PL and TG, on the morphophysiology of Epinephelus marginatus juveniles. A basal diet was manufactured, and DHA and EPA in PL form (PL1-low amount PL2-high amount) and TG form (TG1-low amount; TG2-high amount) were added. Dusky grouper juveniles were equally distributed in 12 tanks of 20 animals each, and liver and muscle were sampled for metabolic analysis. The total hepatic lipids in PL1 and PL2 were higher when compared to the initial, TG1 and TG2 groups. Total lipids in muscle were higher in PL2 and TG1 than PL1 and TG2, respectively. Diets rich in DHA and EPA in PL and TG resulted in higher deposition of these FA in the muscle polar fraction. However, fish fed diets containing lower amounts of DHA and EPA in PL and TG stored those in the muscle neutral fraction and liver, centralizing the storage of DHA and EPA.

Post-spawning feed deprivation effects on testicular and ovarian maturation in the neotropical cichlid fish Cichlasoma dimerus.

Many teleost fishes can withstand long feed deprivation periods, either due to an eventual lack of food or because of their behavior during reproduction and/or parental care. In this work, the effects of total food restriction on the oogenesis, spermatogenesis, and reproductive hormones of the neotropical cichlid fish Cichlasoma dimerus were studied. Specifically, different pairs were isolated after having a spawning event and were feed-deprived or daily fed for 3 weeks. After that period, gonadal histology, messenger levels of genes related to reproduction (gonadotropin-releasing hormone 1, gonadotropins, and insulin-like growth factor 1) and 11-ketotestosterone plasma levels were evaluated in both groups. Food restriction did not affect the reproductive axis in females since follicular maturation and gene expression showed no differences with respect to controls. However, in males, food restriction showed a stimulatory effect on the reproductive axis, reflected in a greater number of spermatozoa in their seminiferous lobes and spermatic ducts, and in an increase in follicle stimulating hormone messenger expression. Despite the negative effect reported for many fish species, C. dimerus seems to redirect their energy reserves towards gonadal development when faced with to a feed deprivation period.

Seasonal and social factors associated with spacing in a wild territorial electric fish.

In this study, we focused on the seasonal variation of the determinants of territory size in the weakly electric fish Gymnotus omarorum. This species is a seasonal breeder that displays year-round territorial aggression. Female and male dyads exhibit indistinguishable non-breeding territorial agonistic behavior and body size is the only significant predictor of contest outcome. We conducted field surveys across seasons that included the identification of individual location, measurements of water physico-chemical variables, characterization of individual morphometric and physiological traits, and their correlation to spatial distribution. G. omarorum tolerates a wide range of dissolved oxygen concentration, and territory size correlated positively with dissolved oxygen in both seasons. In the non-breeding season, territory size was sexually monomorphic and correlated only with body size. In the breeding season, territory size no longer correlated with body size but differed between sexes: (i) the overall spatial arrangement was sexually biased, (ii) territory size depended on gonadal hormones in both sexes, which was expected for males, but not previously reported in females, (iii) female territory size showed a positive relationship with gonadal size, and (iv) females showed relatively larger territories than males. This study demonstrates seasonal changes in the determinants of territory size and thus contributes to the understanding of the mechanisms underlying the behavioral plasticity natural territorial behavior.

Spawning induction and embryonic development of Salminus hilarii (Characiformes: Characidae).

The present study aimed to evaluate two different methods of artificial reproduction induction, and characterize the embryonic development of Salminus hilarii. Different than observed for other tropical fish species, artificial reproduction induction followed by hand-stripping of gametes was considered unfeasible for S. hilarii, as no gamete fertilization was observed. However, females that were induced and spawned naturally presented a fertilization rate of 65.64 ± 0.54%. With a mean temperature of 26.20 ± 0.90ºC it was possible to clearly distinguish a large perivitelline space at 14 min after fertilization (AF) and at 49 min AF more than 50% of the embryos presented two blastomeres, and these cleavages occurred until 1 h 54 min AF. The gastrula phase was characterized at 3 h 56 min AF, and blastopore closure was observed at 8 h 31 min AF. At 9 h 1 min, organogenesis started, with a clear distinction of the yolk mass, embryonic axis, cephalic and caudal regions; at 11 h 51 min AF the embryos already had advanced segmentation and a free tail. Total hatching occurred at 21 h 17 min and after opening the mouth, which occurred at 33 h 9 min, the larvae of S. hilarii presented a strong and characteristic cannibalism. This information can be considered fundamental to improving S. hilarii production in captivity and for collaboration with a conservation programme in the upper Tietê river basin.

Endocrine and reproductive endpoints of Notothenia rossii and N. coriiceps: A baseline study for ecotoxicological monitoring in Antarctic waters.

Pollution threats Antarctica and scientists blame xenobiotics and anthropic activities. Yet little is known about their effect on Antarctic ichthyofauna. Accordingly, we investigated the endocrine system of male fish Notothenia rossii and N. coriiceps (Perciformes, Nototheniidae) collected during Austral summer. For N. rossii, hormone levels of estradiol, testosterone, and 11-ketotestosterone were higher in fish collected during March than those of January; whereas for N. coriiceps estradiol and androgens levels were higher and lower in March, respectively. Histological analysis of the testes showed an unrestricted lobular type with no pathological alterations. However, detection of vitellogenin-like in plasma and skin mucus were seen in 75% of N. coriiceps males and 7% of N. rossii males. This is the first report of mucus vitellogenin-like detection as a non-invasive biomarker of endocrine disruption in notothenioid males and settles a baseline for future studies of reproductive biology and endocrine disruption in Antarctic fishes.

Characterization of the gonadotropin-releasing hormone system in the Neotropical teleost, Steindachneridion parahybae during the annual reproductive cycle in captivity.

This study evaluated by immunohistochemical and Western blot methods, the distribution of two distinct gonadotropin-releasing hormones (GnRHs), corresponding to catfish GnRH (cfGnRH or GnRH1) and chicken-II GnRH (cGnRH-II or GnRH2), in Steindachneridion parahybae females in captivity, focusing these analyses on the reproductive cycle by semi-quantification of optical density (OD). Further, we found that the GnRH neuronal systems co-localized with their respective GnRH-associated peptides (GAPs). A group of neurons immunoreactive (ir) to GnRH1 were identified along the ventral region of the olfactory bulb (vOB) in the telencephalon (vTel) and in the main areas of the diencephalon (especially the medial basal hypothalamus, HBM), including fibers extending into the pituitary gland. In contrast, GnRH2 neurons were confined to the midbrain tegmentum, close to the ventricular surface, without projections to the pituitary gland. Moreover, a cfGAP (GnRH1)-specific band (9 kDa) was identified in the brain and pituitary gland, while a cGAP-II (GnRH2)-specific band (26 kDa) was observed only in the brain extract. During the reproductive cycle, GnRH1-ir presented greater OD values at the vitellogenic and regression stages than at the previtellogenic stage and after artificially induced to spawn. Larger GnRH2-ir neurons were observed during the reproductive cycle, but a higher OD was identified only in the regression stage compared with the other maturation stages. Finally, GnRH1 axons were found to be directed towards the pituitary, and this GnRH type, which is probably the hypophysiotropic form, can contribute to the reproductive dysfunction that occurs in S. parahybae females in captivity, whereas GnRH2 may act as a neuromodulator and/or neurotransmitter.

Environmental pollution affects molecular and biochemical responses during gonadal maturation of Astyanax fasciatus (Teleostei: Characiformes: Characidae).

Endocrine disrupting compounds (EDCs) have the potential to alter fish reproduction at various levels of organization. The aim of this study was to assess the impact of a natural environment with heavily anthropogenic influence on the physiological processes involved in reproduction in the freshwater fish lambari (Astyanax fasciatus) using different biomarkers. Adult males and females were collected in different seasons from two distinct sites in the same watershed: Ponte Nova Reservoir (PN) considered a pristine or small anthropogenic influence reference point; and Billings Reservoir (Bil), subjected to a large anthropogenic impact. Biological indices, such as hepatosomatic index and gonadosomatic index (GSI), gonadal histomorphology, fecundity, and biomarkers such as plasma levels of estradiol (E2) as well as hepatic gene expression of its alfa nuclear receptor (ERα), were analyzed. Hepatic vitellogenin (VTG) gene expression was evaluated in both sexes, as an indicator of xenoestrogen exposure. Females collected at PN presented a typical annual variation reflected in GSI, whereas for those sampled at Bil the index did not change through the seasons. The higher concentration of E2 in males collected at Bil during spring/2013, together with the detection of VTG gene expression, suggest the presence of EDCs in the water. These EDCs may have also influenced fecundity of females from Bil, which was higher during winter and spring/2013. Gene expression of ERα and ovarian morphology did not differ between fish from both sites. Water conditions from Bil reservoir impacted by anthropic activity clearly interfered mainly with biomarkers of biological effect such as plasma E2 levels and absolute and relative fecundity, but also altered biomarkers of exposure as VTG gene expression. These facts support the notion that waterborne EDCs are capable of causing estrogenic activity in A. fasciatus.

Mobilization of energetic substrates in the endangered catfish Steindachneridion parahybae (Siluriformes: Pimelodidae): changes in annual reproductive cycle in captivity

This study aimed at analyzing the energetic substrate (ES) in the main storage tissues of Steindachneridion parahybae, throughout the reproductive cycle in captivity. Differently from wild, in captivity, feeding is not interrupted during the reproductive period, the females do not spawn spontaneously, and they are sedentary. Adult females were sampled monthly and based on their histology and gonadosomatic index (GSI), ovaries were classified into: previtellogenic (PRV), vitellogenic (VTG), and regression (REG) stages. Ovaries at the VTG stage showed higher protein and lipids levels than at the PRV stage with a positive correlation between these substrates and the GSI. Muscle was the main source of proteins transferred to the ovaries, according to the negative correlation between these organs. Lipids remained unchanged in the liver, which is an important supplier in vitellogenesis, a pattern that probably occurs due to the continuous feeding. Muscular glycogen levels were higher at the VTG and REG than at the PRV stages. Plasma triglycerides were also higher during REG, while glucose levels were more elevated during the VTG stage. These results suggest that with constant food supply, the pattern of deposition of ES in S. parahybae is different from that described for other wild potamodromous species.(AU)

O objetivo deste estudo foi analisar a composição do substrato energético (SE) nos principais tecidos de armazenamento de Steindachneridion parahybae, durante todo o ciclo reprodutivo em cativeiro. Diferentemente do ambiente natural, em cativeiro, a alimentação desses animais não é interrompida durante o período reprodutivo, as fêmeas não desovam espontaneamente, e são sedentárias. Fêmeas adultas foram amostradas mensalmente e baseada na histologia e no índice gonadossomático (IGS), os ovários foram classificados: estádios pré-vitelogênico (PRV), vitelogênico (VTG) e regressão (REG). Os ovários no estádio VTG apresentaram uma maior concentração de lipídeos e proteínas em relação ao estágio PRV. Esses substratos correlacionaram-se positivamente com o IGS. O músculo foi a principal fonte de proteína transferida aos ovários, como foi confirmado pela análise de correlação negativa entre esses órgãos. Os lipídeos mantiveram-se inalterados no fígado, considerado um importante órgão fornecedor de lipídeos para a vitelogênese, padrão que possivelmente ocorreu devido à contínua alimentação. A concentração do glicogênio muscular foi mais elevada durante os estágios VTG e REG em relação ao PRV. A concentração de triglicerídeos plasmática apresentou maiores valores no estádio REG enquanto a concentração de glicose no plasma foi maior durante os estádios VTG. Esses resultados sugerem que com alimentação constante, as fêmeas de S. parahybae apresentam um distinto padrão de mobilização dos substratos energéticos em relação ao que já foi descrito para outras espécies potamódromas de ambiente natural.(AU)

This study aimed at analyzing the energetic substrate (ES) in the main storage tissues of Steindachneridion parahybae, throughout the reproductive cycle in captivity. Differently from wild, in captivity, feeding is not interrupted during the reproductive period, the females do not spawn spontaneously, and they are sedentary. Adult females were sampled monthly and based on their histology and gonadosomatic index (GSI), ovaries were classified into: previtellogenic (PRV), vitellogenic (VTG), and regression (REG) stages. Ovaries at the VTG stage showed higher protein and lipids levels than at the PRV stage with a positive correlation between these substrates and the GSI. Muscle was the main source of proteins transferred to the ovaries, according to the negative correlation between these organs. Lipids remained unchanged in the liver, which is an important supplier in vitellogenesis, a pattern that probably occurs due to the continuous feeding. Muscular glycogen levels were higher at the VTG and REG than at the PRV stages. Plasma triglycerides were also higher during REG, while glucose levels were more elevated during the VTG stage. These results suggest that with constant food supply, the pattern of deposition of ES in S. parahybae is different from that described for other wild potamodromous species.(AU)

A game of two? Gene expression analysis of brain (cyp19a1b) and gonadal (cyp19a1a) aromatase in females of a Neotropical cichlid fish through the parental care period and removal of the offspring.

For many species parental behavior is essential for the survival of the offspring. While the ultimate causes of teleost parental behavior have been widely studied, comparatively little is known about its proximate causes. The aim of this study was to analyze the yet unexplored, potential dual role of brain and gonadal aromatases, the enzymes responsible for the conversion of androgens to estrogens in the brains and gonads of teleosts, respectively, on the different stages of the maternal care period of the biparental cichlid Cichlasoma dimerus, locally known as chanchita. By immunohistochemistry we analyzed the neural distribution of brain aromatase and observed it exclusively within the forebrain, including areas involved in the regulation of parental behavior. We next analyzed the gene expression of brain aromatase in the brain, and gonadal aromatase in the ovary, of female chanchitas through the parental care period. To further characterize the physiological environment associated to maternal care, we also evaluated sex steroid levels (17ß-estradiol, testosterone and 11-ketotestoterone) and ovarian follicle percentage. The onset of parental behavior specifically downregulated sex steroids synthesis and the rate of ovarian maturation, as denoted by a more than 10-fold decrease in steroid levels and delayed detection of mature follicles in females with offspring, compared to females which eggs were removed. Gene expression levels of both aromatases were independent of maternal care at the evaluated time points, even though they varied during the parental care period.

Characterization of gonadotropic cells during continuous and seasonal spermatogenesis of two freshwater fish species: a histochemical and immunohistochemical study.

This work describes gonadotropic (GtH) cells and their morphological and immunohistochemical changes during the spermatogenic cycle of Serrasalmus maculatus (continuous spermatogenesis) and Pimelodus maculatus (seasonal spermatogenesis). GtH cells, widely distributed in the proximal pars distalis of the adenohypophysis, were characterized as round-shaped cells with eccentric nucleus, and cytoplasm with basophilic secretory granules and a variable number of vacuoles for both species. Immunohistochemistry against ß-follicle-stimulating hormone (Fsh) and ß-luteinizing hormone (Lh) in adjacent sections showed two separated GtH-producing cell populations, and a third population where both GtHs are expressed in the same cell for both species. In the seasonal spermatogenesis of P. maculatus, GtH cells seemed to be more abundant during developing and spawning capable phases. In contrast, no cyclic changes were detected in the continuous spermatogenesis of S. maculatus, except for the strong immunoreaction for Fsh and Lh in males with intense spermiogenesis. We conclude that changes reported here might reflect the type of spermatogenic cycle (seasonal or continuous) which are under different regulatory mechanisms (environmental and internal cues) controlling the reproduction in these species.

Fatty Acid Composition of Tropical Fish Depends on Reservoir Trophic Status and Fish Feeding Habit.

Eutrophication results in a deficiency of n-3 LC-PUFA (long-chain polyunsaturated fatty acids) in aquatic food chains, affecting fish nutrition and physiology. The trophic transfer of FA (fatty acids) to fish species of different feeding habits was investigated in two reservoirs in southeast Brazil-the mesotrophic Ponte Nova Reservoir (PN) and the hypereutrophic Billings Reservoir (Bil). Total FA profile of stomach contents and adipose tissue, triacylglycerols (TAG), and phospholipids (PL) from liver and muscle of the omnivorous Astyanax fasciatus and the carnivorous Hoplias malabaricus were analyzed by gas chromatography. A prevalence of n-6PUFA, as 18:2n-6 (linoleic acid) and 20:4n-6 (arachidonic acid, ARA) was observed in the stomach contents and in the tissues of A. fasciatus from the PN reservoir. In contrast, n-3 LC-PUFA, as 20:5n-3 (eicosapentaenoic acid, EPA) was accumulated in fish tissues from Bil, resulting in higher n3/n6 and EPA/ARA ratios, compared to fish from PN. This differential FA accumulation was also observed for H. malabaricus, but differences were slightly minor, and no changes were observed in the EPA/ARA ratios between fish from both reservoirs. Regardless reservoir, FA profiles of TAG resembled that of their diet, whereas FA profiles of PL were more conservative and mainly comprised by LC-PUFA. We conclude that reservoir trophic status affected the FA composition of food resources available to these fish species, resulting in differential allocation of n-3 and n-6 FA. As expected, FA profile of the investigated fish species also reflected their feeding habit and physiological demands.

A case of intersex occurrence in Steindachneridion parahybae (Steindachner, 1877) (Siluriformes: Pimelodidae) under captivity condition: a cytogenetic and morphological study

Little is known about reproductive biology of endangered Steindachneridion parahybae , a gonochoristic teleost species inhabiting the Paraíba do Sul River Basin, and herein is the first description of intersex in S. parahybae juvenile. The normal appearance of ovaries and testes in juvenile from the same lot of breeding were also described for comparison, even as cytogenetic analysis was performed in these juveniles. One specimen was a priori classified as female due to the macroscopic characteristic of ovaries, with small yellow oocytes, without fringes (a main characteristic of catfish male), and larger than testes; however the microscopic analysis revealed the presence of ovotestes, including the complete spermatogenesis. S. parahybae had diploid number, 2n = 56 chromosomes with no evidence of differentiated sex chromosomes or supernumerary chromosomes among them. These findings may be due to the result of exposure to endocrine disrupting compounds or may also be influenced by environmental conditions. The possibility of intersexes might also happen spontaneously and it cannot be ruled out. Therefore, the functional significance and reproductive consequences of this anomaly remain to be determined, suggesting that this species may be susceptible to endocrine disruption. These results contribute to gain expertise about reproductive biology of an endangered species in captivity.(AU)

Poco se sabe sobre la biología reproductiva de Steindachneridion parahybae , una especie de teleósteo gonocorístico en peligro de extinción que habita la cuenca del río Paraíba do Sul y en éste trabajo se describe por primera vez la aparición de individuo intersexo en juvenil de S. parahybae . También se describió el aspecto normal de los ovarios y de los testículos de individuos juveniles procedentes del mismo lote de cría para su comparación; se realizó además el análisis citogenético. Un espécimen fue clasificado a priori como hembra debido a las características macroscópicas de los ovarios, con pequeños oocitos amarillos, sin flecos (característica principal de los bagres macho) y más grande que los testículos; sin embargo el análisis microscópico reveló la presencia de un ovotestis, incluyendo una espermatogénesis completa. S. parahybae presentó un número diploide, 2n = 56 cromosomas, sin evidencia de cromosomas sexuales diferenciados o supernumerarios entre ellos. Estos hallazgos pueden deberse al resultado de la exposición de los individuos a desorganizadores endocrinos o estar influenciados por las condiciones ambientales. Sin embargo no se puede descartar la posibilidad de la presencia de intersexos de forma espontánea. Por lo tanto, la importancia funcional y las consecuencias reproductivas de estas anomalías permanecen aún sin ser determinadas, sugiriendo que esta especie puede ser susceptible a los disruptores endocrinos. Estos resultados contribuyen a ampliar el conocimiento de la biología reproductiva de esta especie en peligro de extinción en condiciones de cautiverio.(AU)

The involvement of gonadotropins and gonadal steroids in the ovulatory dysfunction of the potamodromous Salminus hilarii (Teleostei: Characidae) in captivity.

Potamodromous teleosts that require migration to reproduce show dysfunctions that block ovulation and spawning while in captivity. To understand the physiological basis of these reproductive dysfunctions, follicle-stimulating hormone b subunit (fshb) and luteinizing hormone b subunit (lhb) gene expression analyses by real-time quantitative PCR, together with measurements of estradiol (E 2), 17α-hydroxyprogesterone (17α-OHP) and 17α,20ß-dihydroxy-4-pregnen-3-one (17α,20ß-DHP) levels, were carried out throughout the reproductive cycle of the potamodromous Salminus hilarii. The following reproductive stages were evaluated in captive and wild females: previtellogenic (PV), advanced maturation/mature (AM) and regression/spent (REG/SPENT). In the wild females, fshb expression decreased from the PV to the AM stage, and the opposite pattern was detected for E 2, which increased from the PV to the AM stage. fshb was expressed at lower levels in captive than in wild females, and this difference did not change during the reproductive cycle. lhb expression also increased from the PV to the AM stage in both groups, but the wild females at the AM and REG/SPENT stages showed higher lhb expression levels than the captive females. The concentrations of 17α-OHP did not change during the reproductive cycle, and the levels were higher in the captive than in the wild females at all reproductive stages. 17α,20ß-DHP levels did not change between wild and captive females. However, in captive females, the transition from PV to AM stage was followed by an increase in 17α,20ß-DHP levels. These data indicate that dysfunctions in the gonadotropins and steroids synthesis pathways cause the ovulation failure in captive S. hilarii.

Gonadotropins and Growth Hormone Family Characterization in an Endangered Siluriform Species, Steindachneridion parahybae (Pimelodidae): Relationship With Annual Reproductive Cycle and Induced Spawning in Captivity.

The aim of this study was to identify and characterize pituitary cells of Steindachneridion parahybae females in captivity, highlighting the possible relationship with reproductive disorders at this level, since this species shows oocyte final maturation, ovulation and spawning dysfunction in captivity. The localization and distribution of growth hormone (GH), prolactin (PRL), somatolactin (SL), ß-luteinizing hormone (ß-LH), and ß-follicle stimulating hormone (ß-FSH) immunoreactive (-ir) cells in the adenohypophysis was studied by immunohistochemical and Western blot methods. In addition, cellular morphometric analyses and semi-quantification of ir-cells optical density (OD) during the annual reproductive cycle and after artificial induced spawning (AIS) were performed. Results showed that the distribution and general localization of pituitary cell types were similar to that of other teleost species. However, the morphometrical study of adenohypophysial cells showed differences along the reproductive cycle and following AIS. In general, females at the vitellogenic stage presented greater OD values for GH, PRL and SL than at other maturation stages (previtellogenic and regression stages), probably indicating an increased cellular activity during this stage. Conversely, ß-LH OD did not vary during the annual reproductive cycle. After AIS, ß-LH, SL and GH ir-cells showed an increase in OD values suggesting a possible involvement on oocyte final maturation, ovulation and spawning or a feedback control on the brain-pituitary-gonads axis. Reproductive dysfunction in S. parahybae females in captivity may be due to alteration of the synthesis pathways of ß-LH. In addition, GH family of hormones could modulate associated mechanisms that influence the reproductive status in this species.

A multidisciplinary study on social status and the relationship between inter-individual variation in hormone levels and agonistic behavior in a Neotropical cichlid fish.

Social animals with hierarchal dominance systems are particularly susceptible to their social environment. There, interactions with conspecifics and hierarchal position can greatly affect an individual's behavior, physiology and reproductive success. Our experimental model, Cichlasoma dimerus, is a serially-monogamous Neotropical cichlid fish with a hierarchical social system, established and sustained through agonistic interactions. In this work, we aimed to describe C. dimerus social structure and its association with hormonal profiles and testicular cellular composition. We recorded and quantified agonistic interactions from the territorial pair, i.e. the top ranked male and female, and the lowest ranked male of stable social groups. Plasma levels of 11-ketotestosterone (11-KT), testosterone, 17ß-estradiol (E2) and cortisol were measured by ELISA. Results show that territorial pairs cooperatively guarded the territory, but rarely attacked in synchrony. Territorial males had higher testosterone and 11-KT plasma levels than non-territorial males, while E2 and an index of its metabolization from testosterone were higher in non-territorial males. No difference was observed in cortisol levels. Plasma 11-KT and an index of the conversion of testosterone to 11-KT, positively correlated with the frequency of aggressiveness, while E2 showed the opposite pattern. Territorial males had a higher gonadosomatic index than non-territorial males. The quantification of testicular cellular types revealed that the percentage of spermatocytes and spermatids was higher in non-territorial males, while territorial males showed a greater percentage of spermatozoa. Thus, C. dimerus male social position within a stable hierarchy is associated with distinct behaviors, steroid levels and testicular degree of development.

The role of ovarian steroids in reproductive plasticity in Hoplias malabaricus (Teleostei: Characiformes: Erythrinidae) in tropical reservoirs with different degrees of pollution.

Chemicals in aquatic environments may lead to impairment of fish reproduction, but some species display plasticity levels to survive and reproduce in such localities. We investigated the reproductive cycle in a teleost species, Hoplias malabaricus, which inhabits a variety of environments with different degrees of pollution. Adult females were sampled at two locations in São Paulo State (Brazil), the reference Ponte Nova (PN) reservoir and the polluted Billings (BIL) reservoir. Metabolic and endocrine processes were analyzed throughout the annual cycle with special attention to ovarian histology, gonadosomatic index (GSI), fecundity, ovarian energetic substrates and plasma steroids analyses, in addition to physical and chemical analyses of the water. Pollutants were frequent in BIL but not in PN. The GSI, including the predominance of vitellogenic oocytes, was higher in spring and summer in both locations, but the oocyte recruitment dynamics was different. During winter, females from BIL presented vitellogenic oocytes and high levels of 11-ketotestosterone, which indicated precocity in the vitellogenic phase in relation to the females from PN. In animals from PN, high deposition of lipids occurred in the ovaries. However, plasma estradiol levels did not vary throughout the annual cycle. In animals from BIL, plasma estradiol levels peaked during the summer, but the ovarian lipid content remained unchanged throughout the year. The data suggest that the presence of pollutants cause various endocrine and metabolic responses and especially affects reproductive plasticity, which could explain why H. malabaricus survives under unfavorable environments.

Inappropriate management conditions, especially for the regressed class, are related to sperm quality in Prochilodus lineatus.

The aims of this study were to evaluate the characteristics of the reproductive classes and semen quality in curimbatá (Prochilodus lineatus) breeders maintained in two different rearing systems. To achieve this goal, cages (Cs) and earthen ponds (EPs) were used as experimental systems to provide unsuitable and suitable conditions, respectively. The fish were maintained under the experimental conditions for 18 months. During this period, males were randomly sampled every 2 months for biometric analysis (n = 30 per sample) and for an evaluation of selected characteristics of the testes (n = 5 per sample). After this period, males maintained in EPs and males maintained in Cs (CMs) were evaluated in induced breeding experiments. We observed that rearing P. lineatus in a C at a high stocking density for the long 18-month period of study produced reductions in growth, testis development, gonadosomatic index values, and sperm quality in the fish. We found differences between the groups in all the reproductive classes examined, especially in the regression class, which showed a pronounced accumulation of immature germ cells in the CMs. In this group, we also noted a less intense transition from a continuous to discontinuous germinal epithelium, with an extended and abnormal but less intense spermatogenic period resulting in decreases in semen volume and sperm concentration in the breeding season. Together, such dysfunctions resulted in the production of low-quality sperm in the CMs, as demonstrated by lower-quality DNA (as evaluated by the comet assay), low fertilization success, and low hatching success. In conclusion, to ensure high-quality semen in P. lineatus, appropriate management conditions must be provided throughout the reproductive cycle, especially for the regressed class, even in winter, two seasons before the breeding season.