Identification of a novel C2 domain factor in ovaries of orange-spotted grouper (Epinephelus coioides)

Follicle consists of an oocyte and a lot of surrounding follicular cells, and significant interactions exist between the oocyte and the somatic cells. In this study, a novel cDNA has been screened from a subtractive cDNA library between tail bud embryos and blastula embryos in the protogynous hermaphrodite orange-spotted grouper (Epinephelus coioides). Its full-length cDNA is 821 bp, and has an ORF of 414 by for encoding a peptide of 137 aa, which shows 38%, 37%, 33%, and 33% homology with 4 putative proteins screened from zebrafish (Danio rerio). Conserved domain search in NCBI reveals a single C2 domain existing in the C2 domain superfamily proteins, and has only 7 beta strands in comparison with 8 beta strands of C2 domains in other C2 domain superfamily proteins. Artificial sex reversal, RT-PCR analysis and Western blot detection demonstrated ovary-specific expression of the C2 domain factor, and therefore the novel gene was designated as E. coioides ovary-specific C2 domain factor, EcOC2 factor. Moreover, predominant expression of EcOC2 factor was further revealed in grouper mature ovary, and its strong immunofluorescence signals were located between granulosa cells and oocyte zona radiata in grouper mature follicles. The data indicate that the novel EcOC2 factor might be a main component that associates between granulosa cells and the oocyte during oocyte maturation, and might play significant roles in regulating oocyte maturation and ovulation. Further studies on its developmental behaviour and physiological functions will elucidate the interactions between oocyte and the surrounding somatic cells and the underlying molecular mechanisms. (C) 2005 Elsevier Inc. All rights reserved.

Rapid establishment of pure lines of silver carp (Hypophthalmichthys molirix) and bighead carp (Aristichthys nobilis)

The diversity of gynogenetic, artificial sex reversal and natural silver carp and bighead carp is examined using randomly amplified polymorphic DNA (RAPD) method. All of the 187 bands are obtained and 19 (10.16%) of them are polymorphic in gynogenetic silver carp. Meanwhile 32 (15.61%) out of 205 bands are polymorphic in control group. In gynogenetic bighead carp a total of 232 bands are identified and 11 (4.74%) out of them are polymorphic, while 25 (10.37%) out of 241 bands are polymorphic in control group. The genetic distance of four populations is calculated and it is 0.102 and 0.023 for gynogenetic silver carp and gynogenetic bighead carp respectively. The values of natural silver carp and bighead carp are 0.161 and 0.104. From the UPGMA trees constructed based on genetic distance, the sex reversal individuals that match with the gynogenetic female individuals are picked out. A new breeding process of establishing a pure line is developed.

STUDY ON THE MODE OF PRIMARY CONTROL IN THE EGG OF GYNOGENETIC CRUCIAN CARP FOR INHIBITING THE DEVELOPMENT OF 2 TYPES OF SPERM NUCLEI

By comparing the different developmental characteristics of two types of sperm nuclei which were from gynogenetic fish (crucian carp) and amphimictic fishes (red carp, red goldfish and sex-reversal red carp) respectively in the eggs of gynogenetic crucian carp, it was preliminarily revealed that there existed selective inhibiting actions of the primary control in the eggs of crucian carp for inhibiting the development of the two types of sperm nuclei. To homologous sperms, the primary control showed weak effect, thus leading to the decondensation of homologous sperm nuclei at different degrees in the eggs of crucian carp. But to heterologous sperms, the primary control showed strong effects, resulting in the total inhibition of the development of heterologous sperm nuclei. Moreover, our experimental results also showed that the different developmental behavior of the two types of sperm nuclei might have a great relationship to the changes of the sex ratio in the population of gynogenetic crucian carp. The infiltration of "the genetic materials in sperm nuclei" into the female nucleus at random might play an important role in male emergence in the naturally gynogenetic population of crucian carp.

Pre-B-cell transcription factor 1 and steroidogenic factor 1 synergistically regulate adrenocortical growth and steroidogenesis

variety of transcription factors including Wilms tumor gene (Wt-1), steroidogenic factor 1 (Sf-1), dosage-sensitive sex reversal, adrenal hypoplasia congenita on the X-chromosome, Gene 1 (Dax-1), and pre-B-cell transcription factor 1 (Pbx1) have been defined as necessary for regular adrenocortical development. However, the role of Pbx1 for adrenal growth and function in the adult organism together with the molecular relationship between Pbx1 and these other transcription factors have not been characterized. We demonstrate that Pbx haploinsufficiency (Pbx1(+/-)) in mice is accompanied by a significant lower adrenal weight in adult animals compared with wild-type controls. Accordingly, baseline proliferating cell nuclear antigen levels are lower in Pbx1(+/-) mice, and unilateral adrenalectomy results in impaired contralateral compensatory adrenal growth, indicating a lower proliferative potential in the context of Pbx1 haploinsufficiency. In accordance with the key role of IGFs in adrenocortical proliferation and development, real-time RT-PCR demonstrates significant lower expression levels of the IGF-I receptor, and up-regulation of IGF binding protein-2. Functionally, Pbx1(+/-) mice display a blunted corticosterone response after ACTH stimulation coincident with lower adrenal expression of the ACTH receptor (melanocortin 2 receptor, Mc2-r). Mechanistically, in vitro studies reveal that Pbx1 and Sf-1 synergistically stimulates Mc2-r promoter activity. Moreover, Sf-1 directly activates the Pbx1 promoter activity in vitro and in vivo. Taken together, these studies provide evidence for a role of Pbx1 in the maintenance of a functional adrenal cortex mediated by synergistic actions of Pbx1 and Sf-1 in the transcriptional regulation of the critical effector of adrenocortical differentiation, the ACTH receptor.

Control of ovarian development in the yabby (Cherax destructor)

A study under controlled conditions of ovarian development and rematuration in the yabby (Cherax destructot) was undertaken. The purpose of the study was to improve fundamental understanding of the reproductive biology of the species and provide a basis for application to hatchery management in culture. A review was made of the current status of yabby culture in Australia and the present understanding of reproductive biology of decapod Crustacea. The review emphasised factors controlling several aspects of ovarian development, in particular the processes of vitellogenesis. The subsequent study was designed within the context of current hatchery practice and was based on existing knowledge of decapod reproduction, The sexual differentiation of the yabby after hatching was investigated by serial histological sections, and experiments were carried out to investigate the possibility of sex reversal of males. Most of this Investigation was concerned with removing the influence of the androgenic gland in directing male development, with the intent of observing the development of the elementary gonadal tissue into ovary. It was found that in contrast to other crustacean species, the sex of the yabby becomes fixed before the development of external secondary sexual characteristics, and before the androgenic gland can be discerned. Ovarian tissue developed in females at less than 8 weeks after hatching. A preliminary examination was undertaken for feminising parasites in gonadal tissue of a hermaphrodite yabby. Investigation of the ovary after spawning demonstrated that whilst the female was held under constant conditions of temperature and photoperiod, little rematuration occurred. Except for generation of previtellogenic oocytes during the first two days, the gonaciosomatic index remained low for up to 5 months after spawning. If the temperature of the female was reduced to 10°C and maintained constant, the previtellogenic oocytes were partially resorbed over a three week period. Rematuration then commenced, albeit at a low rate because of the reduced temperature, A method for standardising gonadosomatic indices was developed which took into account differences in hepatopancreatic nutrient reserves of individuals and loss of one or more appendages. This part of the study also considered constraints to rematuration and developed a method of accounting for differences in the ability of females to remature after spawning. Experiments were carried out to investigate the effect of crowding and temperature manipulation on initiating ovarian rematuration and to determine the rate of rematuration at 22°C once initiated. The duration of low temperature had no effect on rematuration; an overnight cooling was sufficient to initiate the process, Rematuration to the end of stage 2 vltellogenesis was substantially complete within 10 days. Crowding of females suppressed rematuration, but less than ideal water quality was not found to have any effect. The presence of a male initiated rematuration at a similar rate, but also led to stage 3 vitetlogenesis and spawning. A study was made of the pheromonal influence of the male through water borne factors without success. Rematuration could not be induced in ovigerous females. The literature review indicated that ovarian rematuration was under the control of an ovary stimulating hormone produced by the thoracic nerve ganglia. Attempts were therefore made to stimulate ovarian rematuration by incorporating the thoracic nerve into the diet of females. Attempts were also made to induce the release of ovary stimulating hormone from the thoracic nerve with 5-hydroxytryptamine, and also with octopamine. No effects were found, but a significant difference between the neurophysiology of the yabby and northern hemisphere crayfish was observed, and the implications of this finding are discussed. The study did not produce any conclusive evidence of an ovary stimulating hormone for the yabby. A model of ovarian rematuration which collects the findings of the experimental investigations was developed, and was used to suggest a hatchery broodstock management protocol. This model differs from existing models in that rematuration triggers and nutritional status are considered.

Quality of polyunsaturated fatty acids in Nile tilapias (Oreochromis niloticus) fed with vitamin E supplementation

Freshwater fish are an important source of protein, but they also contain other highly nutritive components such as fats. Polyunsaturated fatty acids (PUFAs) are essential for normal growth, development and reproduction of vertebrates. The antioxidant role of vitamin E in cell membranes prevents fatty acid and cholesterol oxidation, thereby promoting PUFA and subcellular particle stabilization. The effects of vitamin E supplementation on the quality of Nile tilapia (Oreochromis niloticus) carcass were investigated. The experiments were carried out in an experimental laboratory over 106 d. After sex reversal, 400 early juvenile O. niloticus were tested in a completely randomized experiment with 5 treatments (4 repetitions each), consisting of vitamin E monophosphate supplementation at 0, 50, 100, 150 or 200 mg/kg of a base diet. Treatment diets contained equal amounts of protein and energy. Tilapias supplemented with vitamin E contained arachidonic acid (20:4 omega-6; AA) which participates in inflammatory response. Nile tilapia carcasses that received vitamin E at 100 and 150 mg/kg diet had improved carcass quality by increasing the PUFA:SFA ratio and had the highest levels of polyunsaturated fatty acids from the omega-3 (linolenic acid; 18:3 omega-3) and omega-6 (linoleic acid; 18:2 omega-6) series. (C) 2012 Elsevier Ltd. All rights reserved.

Efetividade de métodos de identificação sexual em tilápias-do-nilo (oreochromis niloticus) revertidas sexualmente com hormônio em ração com diferentes granulometrias

Three methods of sexual identification were evaluated in Nile tilapia (Oreochromis niloticus) at ages of 30, 60 and 90 days that were submitted to sexual reversion under administration of androgen hormone 17 alpha-methyltestosterone added to crumble diets with different granules sizes (0.25, 0.35 and 0.50 mm) in dosage of 60mg/kg. The techniques of sexual identification employed were: a) Macroscopic examination of urogenital papilla; b) Microscopic examination of gonads through stain with carmine-acetate and c) Microscopic examination of gonads through histological routine. In the presence of three methods of sexual identification evaluated, histology of gonads has shown the most confident diagnosis. The grain diameters of rations did not interfere in morphological characteristics of gonads, neither in secondary sexual characters of fish.

Muscle delta C-13 change in nile tilapia (Oreochromis niloticus) fingerlings fed lants grain-based diets

The effects of grain-based diets from C3 or C4-cycle plants on muscle delta C-13 change process in Nile tilapia (Oreochromis niloticus) fingerlings were investigated. Two groups of sex reversal males Nile tilapia fingerlings were fed with isoproteic (32.0% DP) and isocaloric (3200 kcal DE/kg) diets, differing from each other by their delta C-13. Muscle samples were collected and the carbon isotopic composition was measured. For C4 diet, the formula for the muscle delta C-13 change related to the intake time of a new diet was delta C-13=- 14.88 - 9.2 1 e(-0.0209t) and the half-life (T) of the muscle carbon was 33.2 days. For C3 diet, the formula was delta C-13 = - 25.43 + 8.59e(-0.0533), with T = 13 days. The C3 diet was considered more appropriate based on its palatability and consequent larger food intake than the C4 diet, resulting in an increased muscle delta C-13 change rate. However, for future studies, would be necessary to mix both the C3 and C4 feedstuffs to formulate diets nutritionally appropriated, with contrasting stable isotopes signatures. Tissue delta C-13 change rate is therefore indicated as a promising tool to better understand the biotic and abiotic factors that influence nutrients utilization from the diet and animal growth. (c) 2006 Elsevier B.V. All rights reserved.

Reversão sexual de rã-touro (Rana catesbeiana) com hormônio masculinizante misturado à ração de girinos

Este trabalho consistiu em testar a eficiência de um hormônio masculinizante (17beta-hidróxi-17-metil-andróxi-4-en-3-ona) na reversão sexual de girinos de rã-touro (Rana catesbeiana). Foram usados 352 girinos com dois a três meses de idade, nos estádios 30 a 36, para testar quatro níveis de hormônio na ração (0, 30, 60 e 90 mig/g) por 45 dias. Após a metamorfose, 167 imagos foram sacrificados e 185 imagos foram criados até a idade de quatro meses e, então, sacrificados. As análises macroscópicas das gônadas e das características sexuais secundárias confirmaram a masculinização nos tratamentos com hormônio. Muitos ovócitos foram observados nos testículos dos imagos revertidos (ovotestis); entretanto, quatro meses após a metamorfose, os ovotestis ocorreram esporadicamente. Concluiu-se que, após a metamorfose, iniciou-se um processo de reabsorção dos ovócitos nos imagos revertidos, culminando com a quase total reabsorção dos ovócitos no quarto mês de idade.

Testicular interstitial cells, and steroidogenic detection in the protogynous fish, Synbranchus marmoratus (Teleostei, Synbranchidae)

The swamp eel, Synbranchus marmoratus, is a freshwater protogynic diandric species. Primary males develop directly as males while secondary males arise from the sex reversal of females. Fishes from Argentine and Brazil inland waters were collected, examined and compared for this study. In order to characterize the interstitial testicular compartment, light and electron microscopy techniques and an enzyme histochemical examination for steroidogenic cells detection were used. The interstitial compartment of S. marmoratus is composed of Leydig and myoid cells, collagen fibers, blood cells, macrophages,and amyelinic nerves. At the ultrastructural level, no differences were observed in the interstitial tissue, either between specimens from the different sampling sites or between primary and secondary males. Leydig cells are present in all testes examined throughout the year. A cytoplasmatic reaction of 3beta-HSD was detected only in Leydig cells during sex reversal and in both type of males, mainly during the regressed and early maturation classes (autumn and winter). Leydig cells possess the typical fine structural characteristics associated with steroidogenesis. Furthermore, in both type of males, during sex reversal and after the spawning period, the number of granulocytes and macrophages present in the testes increased, suggesting that they could be involved in phagocytosis and resorption of damaged cells. (C) 2004 Elsevier Ltd. All rights reserved.

Avaliação da seleção para aumento de porcentagem de flores pistiladas em mamona (Ricinus communis L.)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento gonadal inicial e reversão sexual em Astyanax altiparanae (Teleostei, characidae)

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

Níveis de carboidratos em dietas extrusadas para tilápias-do-nilo revertidas ou não sexualmente

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação econômica e produtiva de tilápia do Nilo, revertida e não revertida, na fase de recria

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nutrição e reversão sexual de tilápia do Nilo: parâmetros produtivos e estrutura do fígado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)