Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The expansion of the shrimp industry depends on scientific advances related to the understanding of reproductive endocrinology that allows the development of aquaculture programs based on biotechnology. An insulin like-androgenic gland hormone (IAG) is synthesized in the male-specific androgenic gland (AG) and it is responsible for sex differentiation in crustaceans. In this study, RNA was extracted from different tissues; amplified cDNA was obtained by reverse transcription-PCR. Nucleotide sequences were analyzed following a bioinformatic approach of the encoding insulin-like androgenic gland hormone gene. This contribution presents the isolation of the partial cDNA encoding IAG from Penaeus vannamei (Lv-IAG), Penaeus occidentalis (LoIAG) and Penaeus stylirostris (Ls-IAG) from the distal region of terminal ampoules. In addition, the molecular characterization of these sequences is provided and the resulting aminoacid sequences were used to establish the taxonomic positioning of the IAG gene among other Decapoda species. The isolation of these partial sequences provides evidence about the anatomical location of the AG in Penaeus and is the basis for further characterize the complete cDNA of the AG-specific insulin-like encoding transcript for all species of the genus Penaeus from the Pacific coast of America.

The anchovy, Engraulis ringens, is an economically valuable fish, and the most heavily exploited resource in the Humboldt Current System. To analyze its genetic structure and diversity, microsatellite markers were developed using 454 pyrosequencing. A total of 27,352 reads containing di-, tri-, tetra-, penta-, and hexanucleotide microsatellite repeat units were identified from 136,537 reads. Among 80 loci containing more than six repeat motifs, 32 primer sets (40%) produced reproducible PCR products, and all of these loci were polymorphic. Some loci showed deviations from HWE and possible null allele’s presence, results of an excess of homozygotes. In an analysis of 45 individuals from one E. ringens population, the number of alleles per locus ranged from 2 to 33, observed heterozygosity ranged from 0.171 to 0.976, and the probability of identity values ranged from 0.006 to 0.513. These microsatellites will be useful for numerous ecological studies focused on this important pelagic fish; including the examination of population genetic structure, estimating effective population size and providing information for fisheries management.

A preliminary experience to study, on a small scale, the movements of the young of the year (YOY) Sphyrna lewini (Griffith & Smith, 1834), in the Mexican Central Pacific, using acoustic telemetry within a nursery area. From October to December 2014 seven sharks were tagged with ultrasonic transmitters and tracked for 68 days within a 14 km2 area associated to a river mouth. The quick shark handling allowed their release in less than two minutes and excellent health condition. Although recaptured sharks up to 105 days after tagging did not show symptoms of scar infection, a slight abrasion in the shark skin was observed after 51 days. The ultrasonic transmitter retention was 75%, and the site fidelity was complete (F = 1) during the first ninety days. For the 135-day period, fidelity was 0.63 (0.40-0.80), and the estimated attrition rate was 0.73 (0.34-1). Ninety-seven percent of detections occurred on soft bottoms and less than 30 m depth. The YOY S. lewini stayed active 24 h a day and performed estimated movements of 11.96 km during that time. The home range for all tagged sharks was estimated to be 4.82 km2 using the minimum convex polygon method (MCP) and 4.89 km2 using the kernel utilization distribution method (95% KUD). The KUD estimation showed two core areas within the study area, is the one located in front of the river mouth the most used.

The inclusion of aquaculture in household agriculture has been related as an opportunity of product and income diversification as wells as to increase food security for farmers. Small-scale fish production has increased in Brazil, even in regions with a pronounced dry season. However, there is no information about the characteristics and technical and economic viability of aquaculture under these conditions. This study was carried out with the objective to characterize the production of tambatinga (♀Colossoma macropomum × ♂Piaractus brachypomus) in water deficit conditions in Tocantins State, Brazil. The study revealed that it is technically possible and economically feasible to produce tambatinga in seasonal ponds. Worth noting was the adaptability of the hybrids which showed a suitable growth and tolerance to the poor water quality conditions. However, in order to achieve production success and financial returns, the adoption of the following procedures are suggested: a) fish stocking as soon as the rainy period starts, b) use of larger juveniles to achieve a higher final weight, c) adoption of pond liming and fertilizing practices previous to stocking, d) water quality monitoring, e) evaluate fish growing performance, f) partial harvesting during the production cycle, and g) total harvesting at the end of the rainy season.

YY technology has been developed in response to the demand of environment-friendly techniques to produce all-male populations in Nile tilapia culture. However, the first part of this technique still requires feminization of XY fry. Use of estrogen mixtures to achieve feminization has never been tested in Nile tilapia, so the aim of this study was to evaluate the effect of different combinations of the three most important estrogens (17a-estradiol E2, diethylstilbestrol DES, and 17a-ethinylestradiol EE2) on sex proportion, growth, and gonadal development. Mixtures evaluated were E2-DES, E2-EE2, DES-EE2, and E2-DES-EE2. No significant differences in growth were observed at the end of the experiment between control fish and fish fed estrogen mixtures. However, final survival was significantly lower (P < 0.05) in fish fed E2-DES and E2-DES-EE2. All estrogen mixture-treated groups produced progenies with a significantly higher (P < 0.001) proportion of males than the predicted 1:1 sex ratio. No significant differences were observed in gonadosomatic index between fish of the control group and fish fed estrogen mixtures. The proportion of deformed gonads was higher in groups fed E2-DES and E2-DES-EE2. The paradoxical masculinization observed in all estrogen mixtures was probably provoked by the interaction of estrogens with androgen receptors or the inhibition of aromatase expression, which resulted in testosterone accumulation and testis development. These results address the need for further research towards understanding the role of steroids in sexual development since these findings add to a short list of studies that report paradoxical effects after using steroids.

This study evaluates the content of polyphenols, flavonoids and anthraquinones from sequential extracts from four algae species from along the Chilean coastline: Desmarestia ligulata, Dictyota kunthii, Laurencia chilensis and Chondracanthus chamissoi. The antioxidant capacity of these extracts was evaluated through three complementary assays: the TRAP, FRAP, and DPPH assays. Additionally, the cytotoxic activity of these extracts was determined through sulforhodamine B assays on two cancer cell lines, one colon (HT-29) and one breast (MCF-7), and one non-tumor control group of epithelial colon cells (CoN). The greatest antioxidant activity was detected in the ethyl acetate and dichloromethane extracts from L. chilensis in its TRAP potential, ethyl acetate of D. kunthii in its FRAP potential, and finally D. ligulata in its DPPH radical scavenging activity. The activities of this D. ligulata and L. chilensis extracts were significantly correlated with their flavonoid contents. In addition, the dichloromethane extracts from D. kunthii and C. chamissoi showed strong cytotoxic activity against HT-29 and MCF-7; however, the activity was not selective. Future research is necessary to purify the bioactive compounds of interest and improve their selectivity for eventual therapeutic use.

The population dynamics of jumbo squid Dosidicus gigas from northwest Mexico was evaluated for the period 1974-2012 using Schaefer’s model, where model parameters were estimated with the catch maximum sustainable yield method (Catch-MSY) using two prior intrinsic population increase rate (r) range values (1.0 to 2.0 and 1.5 to 2.0). Estimated parameters with both prior r ranges were 1.23 and 1.68 yr-1 for r and 243,836 and 190,468 ton for carrying capacity (k), respectively. Corresponding management quantities were 75,147 and 80,098 ton for the maximum sustainable yield (MSY) and 121,918 and 95,234 ton for the biomass at MSY (BMSY). Estimated jumbo squid biomass dropped below the BMSY after 2003, and near to 0.2 k in 2012. The Schaefer’s model showed that declines in estimated biomass were preceded by catches that exceeded the MSY. Strong El Niño-Southern Oscillation events can change the availability of jumbo squid in northwest Mexico through migratory processes and phenotype changes in maturation size, but stock biomass variability is most likely to be caused by fishing.

This record is the first report of black corals (Antipatharia) in shallow waters of the continental coast of Chile, and extends their geographical range in shallow waters of the upper continental shelf of South America by ~3000 km from Ecuador (~1°S) to Coquimbo, Chile (~29°S). Specimens were observed between 70 and 107 m on three underwater video transects executed in July 2016 on the rocky reef El Toro, which is located about 65 km northwest of Coquimbo. The images were taken with the cameras of a remotely operated vehicle (ROV) at a distance of about two meters from the rocks. Although the image resolution does not allow an exact identification of the species, the multi-branched corals were distinguished from other cnidarians as Antipatharia by the dark color of the stem.

An assay on tilapia Oreochromis niloticus and freshwater prawn Macrobrachium americanum in polyculture was conducted during 112 days to study the effect on their blood chemistry and biochemical body composition to determine the feasibility of this polyculture in high density. Six densities were evaluated [T4/5, T9/5, T14/5, T0/5, T9/0, and T14/0; [Ttilapia/prawn (ind m-2)]. In tilapia were evaluated hemoglobin, red cells albumin, globulin, cholesterol, glucose, and triglycerides composition in blood. In M. americanum were evaluated hemocyanin, cholesterol, triglycerides, glucose and total protein in hemolymph. The total content of proteins, lipids, and carbohydrates in muscle and liver of tilapia, and muscle and hepatopancreas on prawns were also studied. Both animals presented significant differences (P < 0.05) in the glucose concentration, tilapia at T9/5 density presented significantly lower concentration (26.25 ± 6.3 mg dL-1) in blood, and prawn at T4/5 presented significant higher concentration (12.2 ± 1.9 mg dL-1). Tilapia monocultures T14/0 displayed significant higher (P < 0.05) carbohydrate concentration in muscle. No significant differences (P > 0.05) appeared in the concentration of lipids and proteins in any tilapia group and proximal composition of muscle and hepatopancreas in prawn. The present study indicates that polyculture in a density T14/5 is similar than monoculture with no effect in blood or hemolymph chemistry and proximal composition of tilapia and prawn. The blood glucose concentration can be considered an indicator of physiological changes for tilapia and prawn when cultured together.

In this study, we reported the species composition and spatial distribution of Scyphomedusae and Cubomedusae from the southwestern Atlantic and Subantarctic region and reviewed the available knowledge of life history traits of these species. We gathered the literature records and presented new information collected from oceanographic and fishery surveys carried out between 1981 and 2017, encompassing an area of approximately 6,7 million km2 (32-60°S, 34-70°W). We confirmed the occurrence of 15 scyphozoans and 1 cubozoan species previously reported in the region. Lychnorhiza lucerna and Chrysaora lactea were the most numerous species, reaching the highest abundances/biomasses during summer/autumn period. Desmonema gaudichaudi, Chrysaora plocamia, and Periphylla periphylla were frequently observed in low abundances, reaching high numbers only occasionally. Phacellophora camtschatica, Aurelia sp., Drymonema gorgo, Atolla chuni, Stygiomedusa gigantea and Pelagia cf. noctiluca were observed always in low numbers. Atolla wyvillei, Stomolophus meleagris, Desmonema comatum and Tamoya haplonema were reported just a few times and mostly individually. Although new species/reports can be found as surveys are undertaken, these results are considered to be the reliable baseline for further ecological studies seeking to understand the ecological role that these jellyfish play in marine ecosystems.