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Salinity is a crucial environmental factor that influences the growth, reproduction, and physiological responses of fish species. Understanding how different salinities affect Liza ramada is essential for selecting optimal conditions for aquaculture. This study aimed to assess the effects of salinity on the growth, osmoregulation, stress response, and maturation of L. ramada in captivity. In this investigation, blood levels of hormones related to growth, adaptation, and stress response were measured, along with glucose levels in L. ramada broodstock raised in the waters of varying salinities. Results indicated that prolactin and growth hormone levels were higher in freshwater and lower in saline conditions. Additionally, these hormone levels increased during gonad maturation across all salinities. In contrast, thyroxine concentrations exhibited a pattern similar to cortisol, with significantly higher levels in saline water compared to freshwater. Mature fish also displayed elevated hormone levels. Glucose concentrations in the fish raised in different salinities followed a similar trend to cortisol levels. Furthermore, triiodothyronine hormone levels varied slightly during maturation and across different salinities. The L. ramada stock in freshwater demonstrated superior growth rates in both length and weight, alongside higher condition factor and survival rates. However, broodstock grown in freshwater had a lower food conversion ratio. In saline environments, L. ramada exhibited increased sexual activity, with a higher frequency of mature gonad stages and elevated values of the gonadosomatic index (GSI) and hepatosomatic index (HSI). In light of these findings, we conclude that freshwater is conducive to the growth of L. ramada, while saline water is essential for achieving sexual maturity. [ABSTRACT FROM AUTHOR]

Understanding the anatomy of endocrine glands in fish allows for the formulation of a strategy for their reproduction. The current investigation aimed to investigate the immunohistochemical identification of hormonal-secreting cells in Mugil cephalus pituitary gland. Antisera against both piscine and mammalian hormones were used to complete the immunohistochemistry of the cell types in M. cephalus pituitary gland. The adenohypophysis and the neurohypophysis made up the two main sections of M. cephalus's hypophysis. Moreover, the adenohypophysis obtained exhibited three subdivisions: rostral pars distalis (RPD), proximal pars distalis (PPD), and pars intermedia (PI). In the glandular portion, seven cell types were identified according to their distribution, immunoreactivity, and grouping. The cells of prolactin (PRL) were acidophilic and occupied most of the RPD. They responded positively and specifically to antiserum against salmon PRL. Positive immunoreactivity was observed by antiserum of human adrenocorticotrophic (ACTH), within the lead hematoxylinpositive (PbH+) cells that surrounded the RPD neurohypophysis. Salmon growth hormone (GH) antiserum produced a specific and intense immunoreactivity in the PPD's acidophilic cells. Furthermore, basophilic cells, exhibiting a strong and distinct immunoreactivity to antisera against the subunits Iβ and IIβ of salmon gonadotropin (GTH), were localized in PPD's central area. The cells thought to secrete thyrotropin (TSH) were located between the PPD and RPD in the neurohypophysis. They underwent an adverse immunoreactivity when reacted to rat thyrotropin (rBetaTSH) antiserum. Within the PI, two cell types were identified: PbH+ cells that immunoreacted with alpha-melanin-stimulating hormone (α-MSH) antiserum and cells that displayed a positive immunoreaction to anti-salmon somatolactin (SL) and were classified as Periodic Acid-Schiffpositive (PAS+). Current pituitary gland immunohistochemistry of M. cephalus may help to explain hormonal alterations that take place during reproduction in the nature, in captivity, or when this fish is receiving hormonal treatments. [ABSTRACT FROM AUTHOR]

The aim of the present research was to improve Oreochromis niloticus reproduction by treating females exogenously with L-thyroxin (T4), which will stimulate the producing of inhibin and activin A during the growth of larvae, with an influence on the growth and survival of larvae. The immunohistochemical examination was carried out on developing larvae from O. niloticus spawners administered T4 and control, examining the allocation of activin/inhibin subunits A and B, as well as the inhibin subunit α, from 1-28 days post-hatching. The injection of the females with T4 hormone had a notable impact on the reproductive activity, leading to an enhancement in the quality of their eggs, as demonstrated by the significantly normal larvae upon hatching. Findings from the immunohistochemical investigation showed that only inhibin/activin βA were obtained in the differentiate kidney, heart, brain, digestive system, and gills. Strong immunoreactivities of inhibin/activin βA were located in all examined tissues and ages, indicating that injections of thyroxin (1 or 5μg T4/g BW) into O. niloticus female significantly improved the yield of them in the growing tissues of larvae. Inhibin/activin βA could control the differentiation and growth of various organs in O. niloticus larvae. Consequently, T4, inhibin, and activin A through direct or indirect means aided in the growth of O. niloticus larvae, as evidenced by the notable increases in larvae weight and length that obtained through the entire experiment. In addition, in comparison to the control, the treated females' larvae had a noticeably greater rate of survival. We could conclude that tilapia females' reproduction is enhanced by external T4 in the blood of females, which then transfers through the eggs to larvae. The thyroid hormone that was transferred seems to influence the production of inhibin/activin A, which could provide a unique growth advantage for the progeny of O. niloticus. [ABSTRACT FROM AUTHOR]

Steroid hormones; androgen and estrogen are thought to be the primary drivers of the tilapia sex differentiation (male and female). Cytochrome P450 aromatase is a steroidogenic enzyme, which changes androgens into estrogens and mediates the biosynthesis of estrogens. The current study investigated the aromatase immunoreactivity in the Nile tilapia's (Oreochromis niloticus) gonads larvae under temperature-induced and sex differentiation that occurs naturally. When the tilapia larvae were subjected to 35°C of high temperatures, the majority of them produced significantly more males (84%) than the controls (38%) at 25°C. The immunoreactivity of the enzyme aromatase was higher during normal ovarian differentiation than during testicular differentiation. This was observed in gonads subsequent to the commencement of ovarian differentiation, which involves the increase in both stromal and germ cells. In all temperature-exposed cases, there was a decline in aromatase immunoreactivity. Temperature caused females to become more masculine to varying degrees in their offspring. Additionally, the aromatase immunoreactivity decreased in males at 35°C. This shows that, for the purpose of drive differentiation toward testis development, aromatase repression within the gonad is necessary. Aromatase immunoreactivity was detected in the cytoplasm of germ cells and, to a lesser degree, in adjacent Leydig cells, following the start of differentiation in testis. This observation suggests that the aromatase immunoreactivity could be involved in the paracrine regulation of spermatogenesis. In conclusion, the temperature endocrine control for the tilapia sex differentiation shown in this research should help produce all-male populations of this fish in a way that is environmentally friendly, safe, easy to understand, and acceptable. [ABSTRACT FROM AUTHOR]

Monitoring the maturation of fish gonads requires an understanding of the locations of reproductive hormone formation both under the influence of environmental factors and under normal conditions. A crucial role in the biosynthesis of active steroid hormones is played by 3β-hydroxysteroid dehydrogenase (3β-HSD). The male and female Oreochromis niloticus gonads at different stages of the annual sexual cycle were analyzed for 3β-HSD using histochemical techniques to pinpoint the locations of steroid synthesis. In females, a specific cell type in the thecal layer, interstitial cells, and ovarian wall epithelial cells exhibited 3β-HSD activity. In males, only Leydig cells (interstitial cells) and lobule boundary cells exhibited 3β-HSD activity. During the stages of sexual maturation and spawning, the Leydig cells' steroidogenic activity increased. Additionally, during the maturing and spawning stages, 3β-HSD exhibited a strong reaction that increased in intensity and the apparent quantity of cells exhibiting a reaction. However, after spawning, the reaction decreased. Furthermore, during the oogenesis process, which is the development of the previtellogenic oocytes to the ripe oocytes, 3β-HSD activity was elevated in the various phases of ovarian maturation. In conclusion, it can be stated that the cells producing steroid hormones in the male and female gonads of O. niloticus have been sufficiently identified, and their steroid hormoneproducing capacity has been demonstrated. Naturally, more research is necessary to apply this finding to the development of fish gonads during the reproduction in aquaculture settings or under situations where this teleost species is concerned to environmental treatments. [ABSTRACT FROM AUTHOR]

Ancient roles of CRF and ACTH in immune-endocrine interactions were obtained early in the development process of fish alimentary canal. The immunolocalization of corticotrophin releasing factor (CRF) and adrenocorticotropic hormone (ACTH) was inspected in the developing gut of Oreochromis niloticus larvae. The aim was to investigate a possible involvement of these molecules early in the integration of immunological and endocrine systems. Immediately after hatching, the gut of O. niloticus is observed as a straight undifferentiated tube, and with the rapid development, it differentiates into four segments: buccopharinx, esophagus, presumptive stomach and intestine. The immunohistochemical investigation showed the immunolocalization of CRF in the growing digestive tract at all stages (from hatching to 42 days post-hatching). Immunoreaction of CRF was detected in the mucosal epithelium of both the undifferentiated gut and the developing esophagus, stomach, and intestine. Furthermore, CRF immunoreactivity was found in the gastric glands of the stomach. The number of CRF-immunoreactive (ir) cells and the strength of immunoreaction gradually increased as the larvae developed, particularly after the exogenous feeding began; 21 days after hatching. Only the goblet cells of the developing intestine exhibited an ACTH immunoreactivity, which increased at 7dph during the yolk sac resorbtion period. A dramatic decrease was recoded in the number and size of ACTH-ir cells associated with the beginning of the exogenous feeding, and at 28 days post hatching, a very weak immunoreaction was produced. The widespread anatomic distribution and early onset of CRF and ACTH activities, in the developing gut, indicate that these molecules play a functional role in food intake, growth, immunological response, and osmoregulation during O. niloticus development, particularly with the start of the exogenous feeding. [ABSTRACT FROM AUTHOR]

The physiological state of mature brood fish is a determining factor for achieving and stimulating a successful spawning process in captivity. In this 2- year investigation, the physiology of mature Liza ramada females was examined throughout the day at various times (24 hours) to ascertain the most suitable time for obtaining mature females raised in both saline water and fresh water in addition to handling them during the spawning season. In addition, blood concentrations of hormones involved in growth, acclimatization, and response to stress, as well as the levels of glucose, total protein, albumin, and the albumin: globulin ratio of L. ramada mature females were all investigated with respect to the factor of time during a period of 24hours. The highest levels of growth hormone, thyroxine, triiodothyronine, prolactin, cortisol, total protein and albumin were recorded at 12 midday and 6 in the morning for mature L. ramada females raised in both saline water and fresh water, respectively. These recorded levels were suitable for attaining a successful spawning and concurrently stimulating the process for L. ramada raised in captivity. Average levels of glucose were recorded for these fish at the aforementioned times. Low levels of the mentioned hormones, total protein, and albumin were observed at 6PM in fish raised in both saline and fresh waters. These hormones play a significant role in growth, acclimatization, stress response during handling, and stimulating spawning of L. ramada. In conclusion, it was proved that the optimal times for obtaining and handling mature L. ramada females during spawning induction are at 12PM for fish raised in saline water and 6AM for fish raised in fresh water. [ABSTRACT FROM AUTHOR]

Introduction: The localization and characterization of the hypophyseal cell types in L. ramada is so far lacking. Aim of the Work: The present study aimed to describe and determine the hypophyseal cells in L. ramada. Material and Methods: Immunohistochemical localization of the hormone-secreting cells in the hypophysis of L. ramada was completed by antisera against both mammalian and piscine hormones. Results: The hypophysis of L. ramada was comprised two main parts, the glandular part (adenohypophysis) and the nervous part (neurohypophysis). The adenohypophysis was divided into three subdivisions; rostral pars distalis (RPD), proximal pars distalis (PPD) and pars intermedia (PI). Seven of hormone-secreting cells were distinguished in the glandular part according to their grouping, distribution, and immunoreactivity. The acidophilic prolactin (PRL) cells occupied the bulk of the RPD and showed positive and specific immunoreaction with salmon PRL antiserum. Lead hematoxylin-positive (PbH+) cells, which were bordered the neurohypophysis in the RPD, gave positive immunoreactivity with human adrenocorticotrophic (ACTH) antiserum. The acidophilic cells of the PPD immunoreacted positively and strongly with antiserum against salmon growth hormone (GH). In addition, the central region of PPD comprised basophilic cells which were showed specific and strong immunoreaction with antisera against salmon gonadotropin (GTH) subunits; Iβ and IIβ. The presumptive thyrotropin (TSH) secreting cells were distinguished in the neurohypophysis between the RPD and the PPD, and they were negative immunoreacted with antiserum against rat thyrotropin (rBetaTSH). Two cell types were found in the PI; the Periodic Acid-Schiff-positive (PAS+) cells which had positive immunoreaction with anti-salmon somatolactin (SL) and the Lead hematoxylin-positive (PbH+) cells which immunostained with anti-alphamelanin-stimulating hormone (α-MSH). Conclusion: The localization of hypophyseal cells of L. ramada, consider as basis for understanding and tracking hormonal changes during its reproductive cycle in captivity. [ABSTRACT FROM AUTHOR]

Hypophyseal homogenate of common carp is considered one of the different hormonal sources for spawning induction in the teleosts. The present work aimed to measure the hormonal concentration of the hypophysis in different carp species, which can be used as a source of hormones for spawning induction in teleosts. The hypophysis of different mature carp species (both males and females); namely, common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella) and silver carp (Hypophthalmichthys molitrix) were evaluated biochemically to discuss their hormonal source. Five hormones in the pituitary gland, including: adrenocorticotropin hormone (ACTH), prolactin hormone (PRL), growth hormone (GH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were analyzed using electrochemiluminescence immunoassay (ECLIA). Compared to female carps, the hypophysis homogenate of male carps recorded lower levels of the measured hormones. The biochemical results showed that the hypophysis homogenate of H. molitrix showed higher levels of 426±13, 118±6, 2355±47, and 1005±35 ng/mg for PRL, GH, LH, and FSH, respectively. Whereas, lower level of ACTH (5±0.5 ng/mg) was recorded compared to those obtained in C. carpio and C. idella. However, the concentrations of those hormones recorded the lowest values in male carpfish, while the concentration of ACTH hormone was higher in male common carp, recording 13±1.2 ng/mg. The present biochemical observations revealed the suitability and effectiveness of the cheap silver carp hypophysis as a spawning inducer in fishes. [ABSTRACT FROM AUTHOR]

Like females of many commercially important fishes, Liza ramada fail to complete ovarian development and do not undergo final maturation (FOM), ovulation or spawning when reared in captivity. The aim of the present work was to investigate the histological and physiological changes during the reproductive cycle of Liza ramada reared in freshwater fish ponds and during induction of spawning in saline water. In the present study, the levels of total thyroxine (T4), triiodothyronine (T3) and cortisol in the plasma of Liza ramada in a complete reproductive cycle were measured in correlation with the seasonal histological changes in gonads. During the reproductive cycle of females, serum triiodothyronine (T3), thyroxine (T4) and cortisol decreased during ovarian early-vitellogenesis and increased during mid-vitellogenesis to reach a peak for both T4 and cortisol. Then, these hormones declined to low levels during late-vitellogenesis. At the prespawning stage, all mentioned hormones re-increased to high levels and finally declined during induction of spawning. There was a decrease in serum levels of thyroid and cortisol hormones coincided with an increase in testicular activity of the fish. T3 and T4 increased during testis ripening to reach a peak during spawning, while cortisol reached a peak during ripe stage and decreased to low levels during spawning. In conclusion, the seasonal changes in thyroid hormones and cortisol concomitant with gonadal maturation and spawning of Liza ramada support role for these hormones in reproduction and stress response of this fish. [ABSTRACT FROM AUTHOR]

Introduction: Gonadotropin releasing hormone (GnRH) is a crucial regulator of gonadal development and reproduction in fish. In addition, it is a possible secretagogue of somatolactin (SL) in teleosts. Little is known about the possible association of GnRH and SL during reproduction of Liza ramada. Aim of the work: The present study was designed to investigate the GnRH and SL immunoreactivities during inducing the final stages of maturation, ovulation and spawning of Liza ramada; to assess the possible actions of these hormones on sexual maturation and spawning of teleosts. Materials and Methods: Histological and immunohistochemical techniques were generally performed to describe the immunoreactivity of both GnRH and SL during ovarian maturation and spawning of Liza ramada. Results: The mammalian GnRH (mGnRH) cell bodies were observed in the medulla oblongata. However, SL-immunoreactive (-IR) cells were detected in the pars intermedia (PI) of the pituitary gland. The GnRH-IR nerve terminals are in close contact with SL-IR pituitary cells. Importantly, the activity of both mGnRH-IR neurons and SL-IR pituitary cells were increased as reflected with the increased cell number and size during sexual maturation and spawning. The activity of these cells was more pronounced as indicated by the increased cells number and size with more immunoreactivity in pre-spawning female. During final maturation and spawning, mGnRH-IR neurons and SL cells showed an increase in the secretory activity as reflected by their small sizes, vacuolated appearance and weak immunoreactivity. Conclusions: Taken together, these findings suggest that the close contact of mGnRH-IR terminals with SL-IR cells in the pituitary, together with the concomitant changes of GnRH and SL immunoreactivity in response to progress in the reproductive events suggest that GnRH may regulate SL release and the regulation of reproductive activity in L. ramada. [ABSTRACT FROM AUTHOR]

The present study aimed to compare between gill rakers of some marine fishes with different feeding habits. A total of 78 specimens in 13 species belonged to 6 fish families: Sparidae (Sparus aurata, Diplodus noct, Rhapdosargus haffara and Boops boops); Family: Mugilidae (Mugil cephalus, Mugil capito and Liza aurata); Family: Siganidae (Siganus rivulatus and Siganus luridus); Family: Synodontidae (Saurida undosquamis and Synodus saurus); Family: Clupeidae (Herklotsichthys quadrimaculatus) and Family: Carangidae (Caranx sexfasciatus) were collected by irregular visits from land fish market in different localities of Egyptian Mediterranean Sea and Suez Gulf; during the period from March, 2014 to November, 2014. Results showed that, the first gill arch formed of one piece, consisting of two limbs (upper and lower limbs). The gill arch carried two rows of gill rakers on its concave border and two rows of gill filaments on its convex one. The gill rakers in the anterior row (oral row) are longer, more in number and more developed than that of the posterior row (aboral row). The gill arch in family Sparidae is bow-like shape. The anterior gill rakers on the first gill arch of most sparid species are short, conical in shape adapted to carnivorous feeding. The gill arch of fish species in Mugilidae is mostly crescent-shaped and rarely bow-shaped. The anterior gill rakers on the first gill arch are long and great in number adapted to detritus feeding. The gill arch in family Synodontidae is V shaped. The anterior gill rakers on the first gill arch appeared as clusters of small tooth patches adapted to piscivores feeding. The gill arch in family Siganidae is hook-like shape. The anterior gill rakers on the first gill arch were needle spine in shape with secondary projections adapted to herbivorous feeding. The gill arch in fish species of Clupeidae is V like shape. Gill rakers are well developed and arranged in only one row. They are numerous and elongated adapted to seizing food items in the plankton feeding. The gill arch in fish species of Carangidae is bow-like shape. Gill rakers are moderate in length and number adapted to carnivorous feeding. According to the different feeding habits, the results showed that, the highest average length of the first gill arch (mm) is recorded in carnivore and piscivore fish. The maximum averages number and the length of the anterior gill rakers are recorded in detritivore fish and plankitivore fish. The highest percentages of the anterior gill raker length /gill arch length ratio (%) are recorded in plankitivore fish and detritivore fish. Results showed that, the maximum inter raker space (μm) and the inter raker space/gill arch length (%) is recorded in carnivore fish. The maximum breadth at the raker base (μm) in the anterior row of rakers is recorded in piscivore fish. The highest breadth at the raker base/gill arch length (%) in the anterior row of rakers is recorded in carnivore, piscivore and planktivore fish. The highest posterior gill raker length (μm) and the posterior gill raker length /gill arch length ratio (%) are recorded in detritivore fish. In conclusion: The morphological characters of the gill rakers in the first gill arch were differ in species studied according to different feeding habits. So that, can be used in determine the fish family and feeding habits. [ABSTRACT FROM AUTHOR]

ABSTRACT The present experiments investigated the effect of water quality characteristics on the condition factor, the ovarian activity, cortisol level, and the immunoreactivity of stress-response cells (adrenocorticotropic hormone; ACTH- and melanin stimulating hormone; MSH- and somatolactin; SL- secreting cells) and gonadotropin (GTH)-secreting cells in the pituitary gland of Nile tilapia, Oreochromis niloticus. After 3 months of exposure to mixtures of water from different sources (Tap and Lake Manzalah waters), with high levels of minerals and heavy metals, water quality affected the number, size, and immunostaining of stress-response-immunoreactive (ir) cells and GTH-ir cells, which showed a dramatic decrease in their size. The integrated optical density (IOD) of immunoreactivity of MSH- and GTH- cells was significantly increased; however, it was significantly decreased for ACTH- and SL- cells. Also, high levels of cortisol were observed in females exposed to waters with high concentrations of minerals and heavy metals. In parallel, low values of gonadosomatic index (GSI%) and the ovarian histology revealed a decrease of maturing follicles concomitant with an increase of atretic follicles in females exposed to Lake Manzalah polluted water. Taken together, the increased activity of stress-response-ir pituitary cells, serum cortisol level and ovarian atretic follicles in response to elevated concentrations of minerals and heavy metals, supports the possible role of ACTH, MSH, and SL in the adaptive stress response of fish. Therefore, minerals and heavy metals must be considered when discussing tilapia aquaculture status. J. Exp. Zool. 323A: 146-159, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The present study deals with demonstrate the reproductive cycle of the broomtail wrasse, Cheilinus lunulatus which monthly collected from coral reef in Abu Galawa lagoon, Hurghada, Red Sea, during the period from December 2011 to November 2012. Results showed that, the averages of male and female gonadosomatic indices (GSI) were gradually increased during spring and summer months. Irregular trend was recorded to the female hepatosomatic index during all months of the year. It may be due to partially spawning in this fish. Shape, weight, size, colour, texture and structure of gonads were changed with the change of maturity stages. The testicular activity can be classified into five stages: immature stage, stimulating spermatogenesis, rapid spermatogenesis, mature (ripe) testis and Spent testis. Seven stages were recognized during the ovarian activity (previtellogenesis, earlyvitellogenesis, mid-vitellogensis, late-vitellogenesis, pre-spawning, ripe and spent stages). The testicular and ovarian developments were initiated when the day length (photoperiod) and water temperature had begun to increase during March to April. During May to August, however, the gradual increase of both photoperiod and water temperature reached its maximum values, gonads had ensured completion of testicular and ovarian development. It was concluded that Cheilinus lunulatus in Abu-Galawa lagoon of Hurghada, partially spawned during a long spawning season, which extended from May to October. It synchronizes between both males and females with coordination to increasing of both photoperiod and water temperature. [ABSTRACT FROM AUTHOR]

The present study deals with the effect of temperature on the development of different tilapia species (O. niloticus, red tilapia, O. aureus and hybrid tilapia (O. niloticus x O. aureus)) during larval rearing, and its subsequent effect on larval growth and survival. The development of the gills and the digestive tract was investigated histologically and histochemically in the developing control and temperature-exposed larvae of different tilapia species. The exposure of different tilapia species larvae to moderate level of temperature (25-35°C) with a mean of 30°C greatly enhanced the development of gills and the digestive system of larvae as indicated by the quantitative and qualitative changes of the mucus composition from predominantly neutral to a mixture of neutral and acid mucosubstances, or acid mucosubstances occurred during the rearing period. This may be due to the direct effect of temperature on food intake and increasing of metabolism, enhanced the immunity of larvae or indirect effect of temperature on sex differentiation and producing high percentage of males which have rapid growth rate than females. Thus, rearing temperature directly or indirectly improved larval growth of different tilapia species, since a marked increase in both, length and weight of larvae occurred during the experimental period. In addition, temperature-exposed larvae also gave a significantly higher survival rate than that of control. It could be concluded that the exposure of different tilapia species larvae to a rearing temperature of 30°C was effective for improvement of development and growth in a safe, simple and acceptable manner, as well as in a friendly approach to the environment. [ABSTRACT FROM AUTHOR]

Abstract: The present experiments were designed to determine the effect of the exogenous treatment of Oreochromis niloticus females with l-thyroxin (T4) on the activation of growth hormone (GH)-secreting cells during larval rearing, and its subsequent effect on larval growth and survival. The ontogeny of GH-secreting cells was investigated immunocytochemically in the developing O. niloticus larvae, from control and T4-treated spawners. A few numbers of GH-immunoreactive cells were observed early one day after hatching. The number and immunoreactivity of GH-secreting cells increased with larval development. The injection of females O. niloticus with thyroxin (1 or 10μg T4/g BW) greatly enhanced the immunoreactivity of GH-secreting cells in the pituitary gland of larvae as indicated by the quantitative and qualitative changes; the increase of both number and size, and strong immunoreactivities of GH-secreting cells, during the rearing period for the larvae produced from T4-treated females. Thus, thyroxin directly improved O. niloticus larval growth, since a marked increase in both, the length and weight of larvae occurred during the experimental period. In addition, larvae from treated females also gave a significantly higher survival rate than that of the control. It could be concluded that exogenous T4 in maternal circulation was transferred into oocytes and larvae. The transferred thyroid hormone appears to play a main role in the synthesis and secretion of GH during the early development of larvae and may confer a distinct advantage for the growth of the offspring of Nile tilapia, O. niloticus. [Copyright &y& Elsevier]

ABSTRACT The present experiments were designed to determine the effect of different stress factors; handling, seawater acclimation, confinement, and induced spawning on plasma cortisol, hydro mineral balance as well as changes in size, number and integrated intensity of somatolactin (SL)-expressing cells in Liza ramada mature females confined to fresh water ponds. The plasma levels of cortisol, PO43−, Na+, and K+ were higher, while Ca2+ and Mg2+ were lower than controls during transportation without anesthesia. By using clove oil (5 mg L−1) as an anesthetic during transportation, the plasma cortisol, PO43−, Na+, and K+ were similar to controls, while Ca2+ and Mg2+ were higher. During seawater acclimation, the plasma cortisol and minerals were significantly higher except Na+ which was lower than controls. In addition, during induction of spawning, the plasma levels of cortisol, PO43−, Na+, K+, and Mg2+ were significantly higher than controls. The SL-producing cells are located in the pars intermedia (PI) bordering the neurohypophysis. The stress affected the number, size, and immunostaining of SL-expressing cells. During seawater acclimation, the size and the integrated intensity of SL immunoreactivity were lower, but the number of these cells was higher than controls. Furthermore, the number, size, and the integrated intensity of SL immunoreactivity were significantly lower than controls during handling and after spawning, which was opposite to confinement. The response of SL-expressing cells in PI in parallel with changes in cortisol and hydro mineral balance induced by stress support the possible role of SL in the adaptive response of fish to stress. J. Exp. Zool. 00A:1-15, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The possibility of inducing and synchronizing spawning can be very useful to facilitate fish farming, particularly in species that achieve ovarian development in captivity without ovulation occuring. The present study was undertaken to observe the morphological and normal embryonic development of thin-lipped mullet, Liza ramada, after spawning induction of fish reared in freshwater fish farms. The use of pregnyl (HCG) as a priming injection at a dose of 20,000IU/kg body weight followed by a second injection of 40,000IU HCG/kg body weight 24h later, proved to be effective in inducing final oocyte maturation, ovulation and spawning in L. ramada at 52–60h after hormonal injection. The mean number of the ovulated eggs for each female was 700±80.3eggsg−1 body weight. The mean rates of buoyancy, fertilization and hatching were 46±7.1, 55±8.4 and 60±6.6, respectively. Fertilized eggs were kept under normal environmental conditions in seawater at 20–21°C. The first cleavage occurred at 40min, epiboly began at 5h, the embryonic body was formed at 24h and hatching occurred at 48h after spawning. Newly hatched larvae were approximately 2.5mm (total length) and similar to those of the other mullet species in terms of external features except no pigment spots were present over the yolk. The mouth and foregut opened on the 5th day after hatching; at which the total length of larvae was 3.5mm; the hindgut and anus had developed prior to hatching. The induced ovulation technique using acute injections of hormones is an important step in the development of the mullet culture. [Copyright &y& Elsevier]

Modeling of soft robotics systems proves to be an extremely difficult task, due to the large deformation of the soft materials used to make such robots. Reliable and accurate models are necessary for the control task of these soft robots. In this paper, a data-driven approach using machine learning is presented to model the kinematics of Soft Pneumatic Actuators (SPAs). An Echo State Network (ESN) architecture is used to predict the SPA's tip position in 3 axes. Initially, data from actual 3D printed SPAs is obtained to build a training dataset for the network. Irregular-intervals pressure inputs are used to drive the SPA in different actuation sequences. The network is then iteratively trained and optimized. The demonstrated method is shown to successfully model the complex non-linear behavior of the SPA, using only the control input without any feedback sensory data as additional input to the network. In addition, the ability of the network to estimate the kinematics of SPAs with different orientation angles θ is achieved. The ESN is compared to a Long Short-Term Memory (LSTM) network that is trained on the interpolated experimental data. Both networks are then tested on Finite Element Analysis (FEA) data for other θ angle SPAs not included in the training data. This methodology could offer a general approach to modeling SPAs with varying design parameters. [ABSTRACT FROM AUTHOR]

Nature and biological creatures are some of the main sources of inspiration for humans. Engineers have aspired to emulate these natural systems. As rigid systems become increasingly limited in their capabilities to perform complex tasks and adapt to their environment like living creatures, the need for soft systems has become more prominent due to the similar complex, compliant, and flexible characteristics they share with intelligent natural systems. This review provides an overview of the recent developments in the soft robotics field, with a focus on the underwater application frontier. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, we investigated the distribution and activities of corticotropin-releasing factor (CRF) and adrenocorticotropic hormone (ACTH) immunoreactive (ir) cells in the brain and pituitary of Liza ramada during ovarian maturation, seawater acclimation, and induction of spawning. Using immunohistochemistry, we detected that CRF-ir cell bodies exist in different brain regions: medulla oblongata (MO), midbrain tegmentum, habenula, nucleus preopticus (NPO), and in a ventral hypothalamic region corresponding to the nucleus lateralis tuberis (NLTP). In the pituitary gland, we detected some ACTH-producing cells in the rostral pars distalis (RPD) containing CRF immunoreactivity. The synthetic and secretory activity of CRF-ir cells in the NPO and MO as well as ACTH-ir cells in the pituitary were enhanced during ovarian maturation. During seawater acclimation, CRF-ir cells in the NPO and MO and ACTH-ir cells in the pituitary showed dramatic increases in their synthetic activity. These cells showed dramatic increase in their secretory activity during spawning induced by human chorionic gonadotropin (HCG) injection in L. ramada. Finally, hormonally induced ovulation was accompanied with elevation of plasma cortisol and depletion of CRF and ACTH immunoreactivity within the brain and the pituitary gland, respectively. Taken together, our findings suggest that mature breeders of L. ramada may respond to stress resulting from ovarian maturation, and seawater acclimation as well as induced spawning. Mechanisms include enhancement of the synthetic and/or secretory activity of CRF-ir cells in the NPO and MO as well as ACTH-ir cells in the pituitary gland along with a rise in plasma cortisol during ovulation, supporting the possible role of these hormones during stress and reproduction in L. ramada. [Copyright &y& Elsevier]

Inhibin and activin, dimeric protein hormones originally isolated from mammalian gonads, are involved in the regulation of vertebrate reproduction. In the present study, we investigated the localization of inhibin and activin subunits (α, βA, and βB) immunoreactivity in the brain, pituitary, and ovary of female Liza ramada using immunohistochemistry. We demonstrate that activin βA subunit immunoreactivity is found in most of the brain regions: telencephalon (Tel), midbrain tegmentum (MT), and cerebellum (C). In the pituitary gland, activin βA subunit immunoreactivity is observed in nerve fibers that are in close contact with somatotrophs and gonadotrophs. Strong immunostaining of activin βB subunit is detected in melanotropin (MSH)-producing cells in pars intermedia (PI), which are in close contact with gonadotrophs.In the ovary, the cytoplasm as well as follicle cells of previtellogenic oocytes exhibited strong immunoreactivity of activin βA. However, the activin βA and βB immunoreactivity is decreased when the oocytes entered the vitellogenic stage (recrudescence). The progress in the accumulation of yolk within oocytoplasm is accompanied by a decrease in the activin βA and βB immunoreactivity and eventually the immunoreactivity disappears completely when the oocytes become fully mature. Interestingly, the vitellogenic oocytes of female L. ramada obtained from fresh water (captivity) contain only weak immunoreactivity of activin βA compared to that of saline water (natural habitat). Moreover, immunoreactivity of activin βB is observed in the phagocytic granulosa cells during resorption of oocytes (atresia) within the ovary of female reared in captivity. The immunostaining of inhibin α in the ovary is similar to that of activin βB but the reaction intensity is weaker. However, the mature oocytes show a positive reaction for inhibin α. These results provide evidence for the presence of inhibin and activin-like molecules within L. ramada and reveal the distribution of these molecules in L. ramada brain–hypophysial–gonadal system. Our observations add some new informations to our current understanding of activin system in fish and suggest that inhibin and activin may play an important role for L. ramada reproduction in the event of oocyte growth and maturation. [Copyright &y& Elsevier]

In the present study we investigated the distribution of gonadotropin-releasing hormones (GnRH) in the brain of Lates niloticus and their association with different pituitary cell types using immunohistochemical techniques. We found immunoreactive (ir) chicken GnRH-II (cGnRH-II) and mammalian GnRH (mGnRH) as the main components of the GnRH-ir system within the brain of the Nile perch. The results indicate that mGnRH and cGnRH are localized in different neurons: mGnRH-ir perikaria were observed in the preoptic region particularly in the organum vasculosum laminae terminalis (OVLT) and in the nucleus lateralis tuberis pars posterior (NLTP) of the mediobasal hypothalamus. These cell bodies are located along a continuum of ir-fibers that could be traced from the olfactory nerve to the pituitary. mGnRH-ir fibers were detected in many parts of the brain (olfactory bulbs, ventral telencephalon, hypothalamus, and mesencephalon) and in the pituitary. cGnRH-ir cell bodies are restricted to the optic tract, but few scattered fibers could be detected in different parts of the brain. The pituitary exhibited very few cGnRH-II ir fibers, contrasting with an extensive mGnRH innervation. Moreover, mGnRH-ir fibers were targeting the three areas of the pituitary gland: rostral pars distalis (RPD), proximal pars distalis (PPD), and pars intermedia (PI). Double immunolabeling studies showed GnRH-ir fibers in close proximity with prolactin (PRL)- and adrenocorticotropic hormone (ACTH)-producing cells in the RPD, growth hormone (GH)-producing cells in the PPD, gonadotropins (GTHs)-producing cells in the PPD in the external border of the PI, and with somatolactin (SL)- and α-melanocyte stimulating hormone (α-MSH)-producing cells in the PI. Our results showed direct morphological evidence for a close association of GnRH-ir fibers with the different adenohypophysial cell types. These results suggest a multiple role of GnRH in the regulation of various pituitary hormones’ release. [Copyright &y& Elsevier]