Hepatosomatic Research Articles

Reproduction of the fish Poeciliopsis gracilis (Cyprinodontiformes: Poeciliidae) in Coatetelco, a tropical shallow lake in Mexico

A reproductive analysis of 1 225 specimens of Poeciliopsis gracilis obtained through monthly samples from Coatetelco, a tropical shallow lake in Central Mexico, was made. There was an evident sexual dimorphism, including a difference in body size at the onset of reproduction. Sex ratio deviated significantly from unity. Monthly variations in gonadosomatic (GSI), hepatosomatic (HSI) indexes and ovarian development stages showed that the spawning season was from July to October, coinciding with the rainy season and phytoplankton biomass increase.

Adipose tissue-derived stem cells promote the reversion of non-alcoholic fatty liver disease: An in vivo study.

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of liver injury and seriously affects human health. In the present study, we aimed to investigate whether adipose tissue-derived stem cell (ADSC) transplantation in combination with dietary modification was capable of reversing the progression of NAFLD. After establishing a rat model of NAFLD by feeding them a high-fat diet (HFD), ADSCs were transplanted via the portal vein into rats with HFD-induced NAFLD, and simultaneously fed a modified diet. Thereafter, gross liver morphology, the hepatosomatic (HSI) index and indicators of liver function, including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) were evaluated. Subsequently, the serum levels of total cholesterol (TC), triglycerides (TGs) and fatty acids (FAs) were also assayed. Furthermore, H&E and oil red O staining were used to confirm the pathological effects of NAFLD in the rat livers. Although dietary modification alone caused liver function to recover, ADSC transplantation in combination with dietary modification further decreased the HSI index, the serum levels of ALT, TBIL, TC, TGs, FAs, reduced lipid accumulation to normal levels, and reversed the hepatic pathological changes in the rat livers. Taken together, these findings suggest that ADSC transplantation assists in the reversion of NAFLD by improving liver function and promoting lipid metabolism, thereby exerting hepatoprotective effects. Thus, we suggest that ADSC transplantation is a promising, potential therapeutic strategy for NAFLD treatment.

Reproductive biology of Poecilia sphenops Valenciennes, 1846 (Cyprinidontiformes: Poeciliidae) at the Emiliano Zapata Reservoir in Morelos, Mexico

ABSTRACT Poecilia sphenops is a native species recently recorded in the Balsas basin and the Amacuzac River in Morelos (Mexico), in which it is abundant and widely distributed. This study analyzed some aspects of the reproductive biology of Poecilia sphenops from the Emiliano Zapata Reservoir, in Central Mexico. Specimens were collected using a 20 m-long seine with a 5 mm mesh size, from January to December 2006. A total of 581 specimens were collected: 407 females (70.0%), 83 males (14.3%) and 91 individuals with no differentiated sex (15.7%). Fish ranged from 20 to 96 mm in total length and 0.01 to 13.07 g in body weight. The female to male sex ratio (4.9:1) deviated significantly from the unity (χ2= 214.2, p<0.05). Monthly variations in gonadosomatic (GSI) and hepatosomatic (HSI) indexes and ovarian development stages showed that P. sphenops spawning season occurred between July and October, concurring with the rainy season. Another reproduction peak was registered in February. The largest length registered for males and females was 96 mm and 83 mm, respectively.

The use of biomarkers to study the effects of the mixture of diuron and hexazinone on small and large O. niloticus

Pesticides have made possible a safer and plentiful supply of food; however, the ultimate sink for many of these contaminants is the aquatic environment. We analyzed the commercial mixture Velpar K® WG, which is composed of the pesticides diuron (46.8% m/m) and hexazinone (13.2% m/m), as well as inert ingredients (40.0% m/m). The present study aimed to evaluate the effects of the herbicide mixture on Oreochromis niloticus of different sizes. To this end, we analyzed biomarkers in small and large O. niloticus exposed to a mixture of herbicides at 125, 250 and 500 ug L-1 for 72h. EROD increased activity in small fish exposed to the herbicide mixture at 250 and 500 ug L-1. The GST activity and levels of the antioxidant enzymes GPx and CAT remained the same in the treated fish, compared with the control. The level of the antioxidant enzyme SOD measured in the fish gills was changed in animals exposed to the herbicide mixture at 250 ug L-1. MDA analysis did not show lipid peroxidation. The comet assay evidenced widespread DNA damage, but the micronucleus test did not show mutagenicity. Hepatosomatic (HSI) analysis did not indicate any alterations in liver morphology. The biomarkers response in the fish depended on the size of the individuals.

Comparison of growth parameters of tiger puffer Takifugu rubripes from two culture systems in China

Growth parameters, such as body weight (BW), viscerosomatic (VSI), hepatosomatic (HSI), and gonadosomatic (GSI), of the tiger puffer Takifugu rubripes reared in two culture systems, open-indoor combination aquaculture system (OIS) and recirculating aquaculture system (RAS) were compared in the present study. At the end of the trial, the tiger puffers in RAS (BW: 878.06±134.61g; GSI: 2.78±0.34%; VSI: 14.33±2.00%; HSI: 9.11±1.63%) obtained higher BW and GSI, but lower VSI and HSI than those reared in OIS (BW: 771.10±170.49g; GSI: 0.44±0.26%; VSI: 18.50±2.98%; HSI: 13.64±2.43%) (P<0.05). Based on the data, slaughter ratio (SR) of the fish in RAS (85.19±1.82%) was significantly higher than that reared in OIS (81.57±3.06%) (P<0.05). Moreover, the male fish grew better than the female in OIS, however the trend was reverse in RAS. Fishes reared in RAS had already entered puberty after ~500days culture. Given the high economic value of soft roe (gonad of male tiger puffer), these results inspired us in carrying out monosex culture to promote the development of tiger puffer industry. Statement of relevanceThis study inspired us in monosex culture of tiger puffer.

REPRODUCTIVE BIOLOGY OF THE VENEZUELA ROUND STINGRAY Urotrygon venezuelae SCHULTZ FROM THE COLOMBIAN CARIBBEAN

&lt;p&gt;As for most batoid species, little is known about the basic biology of the Venezuela round stingray Urotrygon venezuelae (Urotrygonidae). This study presents information about the reproductive biology of the species, including fecundity, embryonic development stage, relationship between maternal size and fecundity, gonadosomatic (GSI) and hepatosomatic (HSI) indices, sex ratios, maturity size and size at birth. With all this information, a preliminary reproductive cycle is proposed. A total of 269 specimens were caught with beach seine in Salguero beach, Colombian Caribbean Sea, between August 2005 and October 2006. We propose for U. venezuelae a biological cycle with three reproductive peaks: November-December, March-April and August. Median sexual maturity size was calculated in 176 mm (total length) for females and 227 mm for males; fecundity ranged between one and six embryos per female. We found that cloacal diameter and liver weight were better predictors for fecundity than total length for U. venezuelae.&lt;/p&gt;

Aging and life history traits of the longnose spiny dogfish in the Mediterranean Sea: New insights into conservation and management needs

Aging chondrichthyans has been characterized as a slow and difficult process, but at the same time it is considered of fundamental importance for the holistic management and conservation of their populations. This study aims to assess the age and growth of the longnose spurdog S. blainville, to correlate the results to the species’ biological features and to compare them with those reported in previous studies that used different aging methods. By counting the growth bands on the enamel surface of the dorsal fin spines, age was estimated in 569 out of 810 individuals that were taken as by-catch from commercial fisheries in the Mediterranean Sea during an 8-year period. Spine morphometrics revealed sexual dimorphism as far as spine length, spine base width and spine weight are concerned. The between-sex differences were also reflected in the length-weight relationships, in the gonadosomatic (GSI) and hepatosomatic (HSI) indices, and in the condition factor (K). All three somatic indices differed significantly among maturity stages, seasons or age classes. The reproducibility of the age readings was considered high based on the estimated CV and APE precision indices. Age bias plots also indicated no significant intra- and small inter-reader variation. The estimated VBGF parameters were: L∞=1097.3mm, k=0.03 yr−1 and t0=−5.58 yrs for females, and L∞=665.5mm, k=0.08 yr−1 and t0=−3.35 yrs for males. Likelihood ratio tests showed that all growth parameters were statistically significantly different between sexes (χ2=38.26, df=3, P<0.001). Females reached higher longevity (28 yrs) than males (22 yrs) and attained maturity at higher age and larger size (T50=17 yrs and L50=568.1mm) than males did (T50=11.3 yrs and L50=460.6mm). S. blainville seems to be a long-lived shark of slow growth and late maturity, a combination of traits indicating a species of great vulnerability to fishing pressure that can only sustain a low harvest rate.

Effects of insecticide Thiodan®on the morphology and quantification of ovarian follicles in lambarisAstyanax bimaculatus(Linnaeus, 1758) in different treatments

Thiodan® is an insecticide which can cause morphological changes in fish tissues, dependent on the concentration. To investigate possible morphological changes, this study evaluated the number and diameter of ovarian follicles in lambaris Astyanax bimaculatus exposed to Thiodan® for 96 h in different treatments at three sub-lethal concentrations: 1.15, 2.3 and 5.6 μg L−1 and a control group without Thiodan®. Females exposed to Thiodan® were divided into four treatments: (i) without acclimation and without food, (ii) without acclimation and with food, (iii) with acclimation for 10 days and without food; (iv) with acclimation for 10 days and with food. In this study, it was noted that the action of Thiodan® at sub-lethal concentrations in a static system did not affect the morphology of follicular development. However, the treatments with acclimation showed lower numbers of primary and secondary follicles when compared to fish from treatments without acclimation. For the groups exposed to Thiodan®, a greater number of atretic follicles were observed compared to the control groups. The follicular diameter of secondary follicles in fish exposed to Thiodan® in the treatment with acclimation and with food was highest in the control group (P < 0.05). Furthermore, the mean gonadosomatic (GSI) and hepatosomatic (HSI) indices of treatments with acclimation were lower than those for treatments without acclimation. These data suggest that the fish may be being affected by the pesticide to which the fish were submitted, and may cause impairment to the follicular development.

Effects of stocking density on mortality, growth and physiology of juvenile Amur sturgeon (Acipenser schrenckii )

To evaluate effects of stocking density on welfare of Amur sturgeon (Acipenser schrenckii), an experiment was designed using three initial stocking densities in flow-through tanks (LSD = 3.7 kg m−3, MSD = 6.9 kg m−3, and HSD = 9.3 kg m−3, respectively) for 60 days. Growth, body composition, and haematological and biochemical parameters were monitored. The mortality and feed conversion rate (FCR) were not affected by stocking density. However, the specific growth rate (SGR), final weight and weight gain in the HSD group were significantly lower than in the LSD and MSD groups. The hepatosomatic (HSI) and viscerosomatic indices (VSI) varied inversely with regard to stocking density. Stocking density did not affect crude protein levels in fish. In contrast, the total lipid level was significantly higher in the LSD group compared to the MSD and HSD groups. The levels of erythrocytes and haemoglobin were positively correlated with stocking density. Serum total bilirubin and urea in HSD group were significantly higher than in the LSD group while serum triglycerides showed opposite tendencies. Differences between treatments were not registered for glucose, total protein and albumin. In conclusion, higher stocking density resulted in increased immunosuppression and enhanced energy mobilization. The latter was necessary to enable Amur sturgeon to cope with crowding.

Partial Replacement of Fish Meal with Poultry By‐product Meal in Diets for Snakehead, Channa striata (Bloch, 1793), Fingerlings

AbstractA 12‐wk feeding trial was carried out to examine the response of snakehead, Channa striata, fingerlings to diets containing poultry by‐product meal (PBM) protein as replacement to fish meal (FM) protein. Fish (mean initial weight 3.98 ± 0.01) were reared in 15 tanks and fed one of five isocaloric (18.5 kJ/g gross energy) diets, in triplicates. Each diet was formulated to contain 45% crude protein and 6.5% crude fat and utilizing protein from PBM to replace that of defatted FM in the following decreasing order; 40, 30, 20, 10, and 0%, respectively. Fish were fed assigned diets to apparent satiation twice daily during the trial, for 12 wk. Water quality parameters (temperature, pH, and dissolved oxygen) were monitored and ranged between 28.5–30.5 C, 6.1–6.6, and 4.61–6.34 mg/L, respectively. Fish survival and growth performance were not significantly (P &lt; 0.05) different among all the treatments. Dietary PBM level did not significantly (P &gt; 0.05) affect the hepatosomatic (HSI) and viserosomatic indices (VSI) in fish and the carcass protein and ash compositions. Muscle lipid was significantly the highest in the 30PBM compared to 0PBM, 10PBM and 20PBM groups, but similar to the 40PBM treatment. The result of this trial indicates that protein from PBM could be used to successfully replace minimum 40% of defatted FM protein in diets for snakehead fingerlings without negative effects on growth and feed utilization.

Development of the male reproductive system in Callinectes ornatus Ordway, 1863 (Brachyura: Portunidae)

This study describes the histology and histochemistry of the male reproductive system in Callinectes ornatus, comparing juvenile and adult developmental stages. We also analyzed changes in the gonadosomatic (GSI) and hepatosomatic (HSI) indices, and the weights of the testis and vas deferens during the development. The results showed that all stages, beginning with the juvenile (JUV), through developing (DEV) and mature (MAT) adult males of C. ornatus produce sperm and spermatophores. During development, testicular lobes showed the same characteristics of production and release of sperm into the seminiferous duct. The vas deferens showed little histological and histochemical change in the epithelium in juvenile and adult males. The differences consisted of the larger amount of secretion in MAT males compared to JUV and DEV ones. The chemical composition of the seminal fluid was similar, but MAT males produced a more homogeneous secretion. Morphological and physiological maturation are not synchronized in C. ornatus, since JUV males produced spermatophores similar to those in DEV and MAT males. However, these JUV are not yet able to reproduce, since they still have the abdomen attached to the cephalothoracic sternum. The increase of the GSI during development was significant for MAT males, and is related to the production of sufficient volume of seminal fluid to form the sperm plug in the female seminal receptacle. The HSI decreased from DEV to MAT adult stages, indicating that reserves from the hepatopancreas are used to develop the reproductive system after the pubertal molt.

The biological and reproductive parameters of the invasive armored catfish Pterygoplichthys disjunctivus from Adolfo López Mateos El Infiernillo Reservoir, Michoacán-Guerrero, Mexico

Invasive Pterygoplichthys disjunctivus (Weber, 1991) (synonymy: Liposarcus multiradiatus) armored catfish were first reported in Mexico in 1995 and have spread successfully in several aquatic ecosystems. In Adolfo López Mateos El Infiernillo Reservoir, Michoacán - Guerrero, the population of this armored catfish is growing substantially because natural predators are not present and exploitation by humans does not occur. Over a complete annual cycle, we studied the following population parameters: weight, total and standard length, the relationship of weight to total length, the hepatosomatic (HSI) and gonadosomatic (GSI) indices, total fecundity (TF) and relative fecundity (RF). The average total (TL) and standard lengths (SL) were 248 ± 37.5 and 188 ± 30.7mm, respectively, and the average weight (W) was 135.3± 66.8g. The largest fish reported was 520mm in TL and weighed 1 280g. The species showed an extended reproductive season from May to November, as indicated by the GSI, TF and RF. The strongest reproductive peak occurred from July through October. During the annual cycle, the highest monthly average fecundity was 2 447 eggs, and the average relative fecundity was 12.6 eggs per g of fish (August and September). This information will be crucial for calculating the current biomass and future growth of the population. The calculation of these results could provide a basis for the exploitation of this resource for human consumption and animal feeds.

Vitellogenin levels in hemolymph, ovary and hepatopancreas of the freshwater crayfish &lt;i&gt;Cherax quadricarinatus&lt;/i&gt; (Decapoda: Parastacidae) during the reproductive cycle.

The freshwater crayfish Cherax quadricarinatus is a tropical species of great interest for aquaculture. Vitellogenin (Vg), a lipoprotein precursor of the vitellum accumulated in spawned eggs, can be synthesized in the ovary and/or hepatopancreas of most crustaceans, being the hemolymph the way for transporting Vg throughout the reproductive cycle. Concentration of Vg in hemolymph, ovary and hepatopancreas of Cherax quadricarinatus adult females was measured by means of ELISA, specifically developed after purifying the native Vg. Measurements were made at four periods of the reproductive cycle: pre-reproductive, mid-reproductive, late reproductive and post-reproductive. Besides, both hepatosomatic (HSI) and gonadosomatic (GSI) indexes were determined in each period. Significant variations in Vg levels were detected in both hemolymph and hepatopancreas, being the highest values observed during the mid-reproductive period. Besides, such variations were positively correlated to the HSI. A positive correlation between Vg levels in hepatopancreas and ovary was also seen. These results support previous evidences about the central role of the hepatopancreas as a site of Vg synthesis in the studied species, together with the relevancy of hemolymph for transporting Vg from the hepatopancreas to the ovary. For aquaculture purposes, Vg monitoring in hemolymph could be used as a non-injurious method, to check the reproductive activity of C. quadricarinatus females.

Effect of timing of hormonal induction on reproductive activity in lambari (Astyanax bimaculatus)

The objective was to evaluate the influence of the timing of hormonal induction, using gonadorelin or common carp pituitary extract (CPE), on the reproductive activity of female Astyanax bimaculatus. Fish (N = 44) were weighed, measured, and acclimatized to experimental conditions with a photoperiod of 12 h:12 h light:dark (L:D) for 10 days. Ovulation was induced with a single dose of CPE (6 mg/kg) or gonadorelin (80 μg/kg), given at 12:00 (halfway through the light phase (LP) or 24:00 (halfway through the dark phase (DP), in a 2 × 2 factorial design. The time of ovulation was calculated in degree hours and daily motor activity was recorded using a photocell. The fish were killed and the liver and gonads were weighed for calculation of gonadosomatic (GSI) and hepatosomatic (HSI) indexes, respectively. Absolute fecundity (AF), absolute fecundity relative to weight (AFRW) and length (AFRL), diameter of oocytes (mM), and percentage of oocytes with the germinal vesicle in a peripheral position (PPGV) were recorded. All females responded (ovulated). The female Astyanax bimaculatus had twilight motor activity rhythm. Females given CPE at 12:00 had a higher (P < 0.05) percentage of oocytes with the germinal vesicle in a peripheral position compared with the group that received gonadorelin in the same period (95 ± 6 vs. 79 ± 21%, mean ± SD). The absolute fecundity relative to weight was higher in groups induced at 12:00, regardless of the hormone used (LP: 805 ± 448 and 700 ± 214, for CPE and gonadorelin, respectively; dark phase: 580 ± 396 and 529 ± 105, P < 0.05). Both times used for hormonal induction with CPE and gonadorelin were suitable for inducing reproduction in lambari, although induction with CPE in LP had the best results.

Spermatogenesis, Spermatophore, and Seminal Fluid Production in the Adult Blue Crab Callinestes danae (Portunidae)

Sperm and spermatophore production in Callinectes danae Smith, 1869 were examined by histochemistry and correlated with gonadosomatic (GSI) and hepatosomatic (HSI) indices. The GSI from developing (DE) and mature (MAT) males increased while the HSI decreased from DE to MAT, demonstrating that the maturation of the male reproductive system requires resources from the hepatopancreas. No histological or histochemical differences were observed between DE and MAT except for the larger amount of secretions produced in MAT. Spermatogenesis occurs in the seminiferous lobules surrounded by accessory cells. Each lobule is filled with cells at the same developmental stage. Spermatid maturation is characterized by an increase in the metachromatic acrosome. Sperm are released into seminiferous ducts, which moves them to the vas deferens divided into anterior (AVD), median (MVD), and posterior (PVD) regions. Spermatophore formation begins at the anterior part of AVD; sperm masses are separated and compacted in small packets by a basophilic and alcianophilic secretion. Small amounts of eosinophilic secretion, positive for proteins and neutral polysaccharides, are added around the sperm initiating the formation of the spermatophore wall. Mature round spermatophores are found in the posterior part of AVD and present a thick glycoproteinaceous wall, surrounded by acidic polysaccharides. The spermatophores are stored in MVD without size difference from DE to MAT. The MVD is filled with a granular secretion composed of glycoproteins. The secretion in PVD is fluid and homogeneous, facilitating the transference of the spermatophores. In conclusion, the hepatopancreas is related to the maturation of the male reproductive system in C. danae. DE males presented all histological conditions to fertilize females as MAT males, but the decrease in HSI and increase in GSI indices correlated with the vas deferens indicate that reserves are necessary to produce large amounts of seminal fluid in MAT males.

Slaughter yield and growth performance indexes of pikeperch (Sander lucioperca (L.)) selects reared in recirculating aquaculture systems at suboptimal temperatures

The aim of the study was to determine the impact diet has on the basic growth performance indexes and slaughter yield of pikeperch selects (body weight > 1.35 kg). Tagging the individual fish with PIT tags also permitted determining the impact of sex on the studied growth performance indexes. The fish were fed two diets with protein/fat/carbohydrate ratios of 50.5/11.8/29.4 in group I and 47.1/14.1/29.0 in group II. Neither the diets nor the sex of the fish has a significant impact on the final body weight or condition of the pikeperch (P > 0.05). Significant differences were noted between the relative indicators of pikeperch growth performance (SGR and DGR) (impact of diet and sex; P < 0.05). Among the growth performance indexes analyzed, e.g., viscerosomatic (VSI), hepatosomatic (HSI), and gonadosomatic (GSI), statistically significant differences were noted with regard to HSI (impact of diet and sex) and GSI (impact of sex) (P < 0.05). The analysis of the relative values of the pikeperch body parts studied (expressed in % body weight) indicated that the studied parameters had significant impacts on the slaughter yield of the viscera (impact of sex) and skin (impact of diet), as well as on gutted whole fish, gutted and headed whole fish, fillets with skin, and skinned fillets (impact of sex) (P < 0.05). The slaughter yields of the skinned fillets of males from both dietary treatments were approximately 5% higher than those of the females.

Environmental risks of two chitin synthesis inhibitors on Gambusia affinis: Chronic effects on growth and recovery of biological responses

To reduce the impact of conventional insecticides, new more selective chemicals need to be developed. Insect growth regulators such as chitin synthesis inhibitors seem promising because of their specific mode of action on insect and their lower toxicity against non-target organisms than conventional insecticides. Dimilin (25% WP) and andalin (25% EC), the respective trade names of diflubenzuron (DFB) and flucycloxuron (FCX), are two chitin synthesis inhibitors belonging to the class of benzoylphenylurea. In the present study, the toxicity of these insecticides was evaluated on growth and metric indexes in adult females of a larvivorous fish, Gambusia affinis (Cyprinodontiformes, Poeciliidae), extensively used in biological control of mosquitoes. In addition, the compounds were tested on amount of glutathione (GSH) and on glutathione S-transferase activity (GST). The exposure regime included an insecticide exposure period (28days) and a recovery period in untreated water (8days). The compounds were tested separately. Each compound was added in rearing water at two concentrations corresponding to LC50 and LC90 against fourth instar larvae of Culex pipiens (Diptera, Culicidae). The adult females were exposed in a continuous treatment for 28days. The growth, metric indexes, GSH and GST activities were determined at different exposure times (0, 7, 14, 21 and 28days). The results showed that DFB and FCX had no significant (p>0.05) effects on growth, hepato-somatic (HSI) and gonadal-somatic (GSI) indexes, while only FCX at LC90 reduced significantly (p<0.05) the condition factor starting day 21 of exposure. Furthermore, treatment affected both GSH amounts and GST activities. The observed effects varied as function of tested insecticide, exposure time and concentration. The response appeared more marked with FCX. The recovery study showed that this fish species was able to overcome relatively rapidly the stress induced by these insecticides. The overall results suggested that FCX and to a lesser extent also DFB exhibited slight toxic effects on this non-target fish species, and can be used for controlling of mosquitoes in an integrated manner.

Effects of 17β-trenbolone in male eelpout Zoarces viviparus exposed to ethinylestradiol

To evaluate the interaction between 17beta-trenbolone (TB) and 17alpha-ethinylestradiol (EE2), male eelpout, Zoarces viviparus, was exposed for 21 days (April to May 2008) to 5 ng l(-1) EE2 and 5 or 20 ng l(-1) TB, separately or in combination in a flow-through SW system. The effects on hepatosomatic (HSI) and gonadosomatic index (GSI), plasma vitellogenin (Vtg) concentration, gonadal histology, hepatic and testicular Vtg mRNA and estrogen receptor (ERalpha) mRNA expression were investigated. No effects on HSI were observed. A significant decrease was observed in the GSI of all males exposed to EE2 (<0.7%) when compared to controls (1.4%). Histological alterations and immature stages were observed in the testis of all exposed males; however, males exposed to EE2 were the most affected. Increased tubule number and proportionally decreased tubule diameter were observed in the testis of all EE2 groups. No effects in Vtg mRNA expression were observed in the testis; however, a significant decrease in testis ERalpha mRNA was observed in males exposed to 20 ng l(-1) TB. The groups exposed to EE2 showed a significant increase in plasma Vtg (>300-fold), hepatic Vtg mRNA (>450-fold), and ERalpha mRNA (>100-fold) when compared to controls. This study shows that lower concentrations of 17beta-trenbolone are unable to counteract the EE2 estrogenic effects when the exposure is simultaneous.

Fluctuations in the biochemical composition of the Patagonian stone crab &lt;em&gt;Platyxanthus patagonicus&lt;/em&gt; A. Milne Edwards, 1879 (Platyxanthidae: Brachyura) throughout its reproductive cycle

We analyzed the gonadosomatic (GSI) and hepatosomatic (HSI) indices, reproductive condition and biochemical composition of the digestive gland, gonads and claw muscle of the Patagonian stone crab over a one-year period. In females, the maximum HSI occurred in spring (gonad recovery period) and summer (maximum maturity period). The maximum female GSI values were found in summer, and fell to minimum values in fall and winter. In males, the highest GSI was observed during winter, which coincided with a non-mating period. The claw muscle biochemical composition did not significantly differ between seasons for either sex, except for the significantly lower glycogen content observed in winter relative to fall and summer in males. For both sexes, the claw muscle contained 72.4 to 81.2% moisture, 12.3 to 19.8% protein, 0.3 to 1.0% fat, 1.1 to 2.7% ash and 0.1 to 1.4% glycogen. In both sexes, the digestive gland was the main storage site for lipids. In the ovary, lipid and protein contents were higher in spring and summer, and decreased to significantly lower values after spawning. Moisture showed the opposite pattern and neither glycogen nor ash contents showed significant differences between seasons. The biochemical composition of the testes-vasa deferentia complex did not show significant seasonal fluctuations, except for higher moisture content in fall compared to summer and spring.

Reproductive cycle of female yellow snapperLutjanus argentiventris(Pisces, Actinopterygii, Lutjanidae) in the SW Gulf of California: gonadic stages, spawning seasonality and length at sexual maturity

Summary The yellow snapper (Lutjanus argentiventris) in the SW Gulf of California is being heavily fished and little information exists on status of this exploited population. From August 2001 to May 2003, 440 specimens in the size range of 10.8–59 cm were collected from four fishing areas: Huizache-Caimanero, Mazatlan, Marmol and Santa Maria la Reforma in the SW Gulf of California. Specimens were collected from fishermen and obtained by sampling with gill nets, hook and line and spear gun fishing. Gonadal stages, spawning season and length-at-first maturity were estimated for female yellow snapper through histological analyses and relative gonadosomatic (GSI) and hepatosomatic (HSI) indexes. Six gonadal stages were identified and gonadal development was asynchronous. Gonads in advanced stage VI of vitellogenesis occurred during summer and winter together with the highest values of the GSI and HSI, indicating that spawning occurred during these seasons. Mean maturity length was determined to be 32.6 cm total length. The yellow snapper population was being adversely affected considering that the species was exploited throughout the year, including the reproductive seasons, and that organisms as small as 10 cm were found in fishermen’s catches and at fish markets. Minimum capture sizes of 33 cm and a closed season during the reproductive periods of summer and winter are suggested as measures to reduce the adverse affects of this exploitation.