The development of the reproductive organs of the hybrid grouper cantik (Epinephelus fuscoguttatus x E. polyphekadion)

Observation of the reproductive organs of the hybrid grouper cantik was carried out. Cantik grouper is the result of cross-breeding between female tiger grouper Epinephelus fuscoguttatus and male camouflage grouper E. polyphekadion. This study aimed to determine the development of the reproductive organs of cantik grouper. The observed test fishes were 3 fishes of Cantik grouper with a total length of 42 - 49 cm and a bodyweight of 1.45 - 2.26 kg. The parameters observed were the concentarion of estradiol and testosterone in the blood using the ELISA kit, gonad development, and histological maturity level of the gonads. The results showed that the hormone testosterone found in the sample cantik no 1 was 9353 pg/ml, while the hormone estradiol was found in all samples of beautiful grouper in the range of 291 - 1133 pg/ml. From the dissected fish, the gonads had developed and weighed 3.12 - 56.01 g and one sample had a fecundity of 265,800 eggs with an egg diameter of 360-520 micron. Gonadal histology shows oosit development at maturity levels I, II, and IV. This indicates that the crossbreeding between female tiger grouper and male camouflage grouper produces hybrid grouper cantik that are fertile, which is shown by their reproductive organs to have developed well.

Gonadal histology of adult western mosquitofish (Gambusia affinis) following early life exposure to 17α-ethynylestradiol, 17β- trenbolone, and/or atrazine

Confined animal feeding operations (CAFOs) are a source of endocrine disrupting compounds (EDCs) in the aquatic environment and introduced there through agricultural runoff and insufficient waste storage systems. This study used the three compounds 17α-ethynylestradiol (EE2), 17β- trenbolone (TB), and atrazine (Atr) alone and in a mixture representing a simulated CAFO runoff. Laboratory exposures were performed in order to assess if early life exposure during the period of sexual differentiation to CAFO runoff altered gonadal development in western mosquitofish (Gambusia affinis). Juveniles were exposed to low and high concentrations of EE2 (50 or 250 ng/L), TB (10 or 50 ng/L), Atr (150 or 1,500 ng/L), or simulated CAFO runoff (50 ng/L EE2, 10 ng/L TB, and 150 ng/L Atr or 250 ng/L EE2, 50 ng/L TB, and 1,500 Atr) for 30-days followed by a 46-day recovery period. Gonadal histology was measured in adult males and females to assess stages of sexual development (i.e., oogenesis or spermatogenesis) and gonadal histopathology. All of the ovaries analyzed were in the maturing or mature stages of oogenesis, and all of the testes examined were in the intermediate or advanced stages of spermatogenesis. Intersex was observed in one individual exposed to 1,500 ng/L Atr. Ovarian histopathology was normal in all females, however testicular histopathology showed a loss of cyst structure leading to unbound interstitial sperm cells and unsynchronized cyst development in all males except the control fish. This study provided some evidence that exposure to simulated CAFO runoff and its individual compounds impaired testicular development.

Effects of the Thyroid Endocrine System on Gonadal Sex Ratios and Sex-Related Gene Expression in the Pufferfish Takifugu rubripes

To examine the effect and mechanism of thyroid hormone on gonadal sex differentiation, Takifugu rubripes larvae were treated with goitrogen (methimazole, MET, 1000 μg/g), and thyroxine (T4, 2nM) from 25 to 80 days after hatching (dah). Gonadal histology and sex ratios of fish were then determined at 80 dah. MET treatment induced masculinization, but T4 treatment did not induce feminization in T. rubripes larvae. Transcriptomic analysis of gonads at 80 dah was then conducted. Among the large number of differentially expressed genes between the groups, the expression of foxl2, cyp19a1a, and dmrt1 was altered. The expression of foxl2, cyp19a1a, dmrt1 and gsdf at 25, 40, 55 days after treatment (dat) was further analyzed by qPCR. MET treatment suppressed the expression of foxl2 and cyp19a1a, and induced the expression of dmrt1 in genetic females (p < 0.05). Additionally, T4 treatment induced an increase in the expression of cyp19a1a in genetic XY gonads only at 25 dat. However, the increase in cyp19a1a expression did not continue to 40 and 55 dat. This may explain why feminization of larvae was not found in the T4-treated group. Thus, the present study provides the first evidence that MET treatment causes masculinization in teleost fish. The effects of MET-induced masculinization in T. rubripes may act primarily via suppression of the expression of foxl2 and cyp19a1a, and stimulation of the expression of dmrt1. Moreover, the effects of higher concentrations of T4 or different concentrations of T3, on sex differentiation require further testing.

Passive Biomonitoring Using Integrated Hepatic Oxidative Stress Biomarkers and Gonadal Histopathology in Oreochromis Niloticus From Lake Manyame, Zimbabwe

The aquatic environment is particularly vulnerable to the effects of contaminants as effluents from municipal and industrial wastewater continually add numerous harmful exogenous compounds. Lake Manyame is a peri-urban freshwater reservoir that is subject to municipal and industrial discharge as well as agricultural run-off. Adult Nile tilapia (Oreochromis niloticus) were sampled from L. Manyame during low-flow and high-flow seasons from selected locations. The samples were processed in the field for histology and biochemical analysis of selected biomarkers of oxidative stress. Induction of reduced glutathione (GSH), carboxylesterase (CES) and malondialdehyde (MDA) was evident at all the sites. There were no significant variations between sites except in the last low flow season and there was an upward trend between the first season and the subsequent sampling periods. Gonadal histology did not show occurrence of any intersex as a sign of endocrine disruption. The prevalence of histological lesions in the gonads was highest in the last sampling seasons, suggesting a progressive deterioration of water quality over time.

Breeding Biology of Freshwater Goby Glossogobius Giuris Using Gonadosomatic Index and Gonadal Histology

The breeding season of fishes plays an important role in fish domestication and conservation of fish diversity. Freshwater goby, Glossogobius giuris is an important food fish of Bangladesh. Therefore, a study was performed to determine the breeding biology through assessing the gonadosomatic index (IG), fecundity and histology of gonad of G. giuris. A total of 1371 females and 1051 male fishes were collected from the Belai beel of Gazipur district. Significantly (P<0.05) higher values of mean IG were observed during March and from June to August for both females and males. The highest mean fecundity was recorded in August and the lowest was recorded in May. The smallest mean oocyte length was 0.037±0.005 mm in May and the largest was 0.071±0.001 mm in August. The early and late perinucleolar stages of oocytes were observed from January to March. The yolk vesicle stage was observed during April to May and yolk granule stage was observed during March and from June to August. These results revealed that G. giuris might breed in March and from June to August. Ann. Bangladesh Agric. (2019) 23(1) : 1-13