This research was implemented to study the effects of androgenic gland ablation in the white shrimp Litopenaeus vannamei to explore sex reversal potential as an alternative technology for monosex female mariculture based on the sex dimorphic growth of this species. The surgical procedure was applied to male postlarvae (PL) at different ages, after external sex differentiation, as well as in sex undifferentiated PL. Andrectomized males regenerated normal appendices including pereiopods and pleopods; however, body growth and relative size of regenerated petasmas and appendices masculinae were statistically inferior (P ˂ 0.05) to control males. Spermatogenesis in andrectomized males was active, but a phenomenon of degradation of spermatids and reproductive tissues was detected. No sex reversal was accomplished regardless of PL age from sex undifferentiated stages (PL38) to sex differentiated stages (˃PL55). The complete regeneration of sexual characters in andrectomized L. vannamei (Dendrobranchiata) is different from previous reports from Decapoda.

Costa Rica has a significant number of snakebites per year and bacterial infections are often complications in these animal bites. Hereby, this study aims to identify, characterize, and report the diversity of the bacterial community in the oral and cloacal cavities of venomous and nonvenomous snakes found in wildlife in Costa Rica. The snakes where captured by casual encounter search between August and November of 2014 in the Quebrada González sector, in Braulio Carrillo National Park. A total of 120 swabs, oral and cloacal, were taken from 16 individuals of the Viperidae and Colubridae families. Samples were cultured on four different media at room temperature. Once isolated in pure culture, colonies were identified with the VITEK® 2C platform (bioMérieux). In order to test the identification provided on environmental isolates, molecular analyses were conducted on 27 isolates of different bacterial species. Specific 16S rDNA PCR-mediated amplification for bacterial taxonomy was performed, then sequenced, and compared with sequences of Ribosomal Database Project (RDP). From 90 bacterial isolates, 40 different bacterial species were identified from both oral and cloacal swabs. These results indicate the diversity of opportunistic pathogens present and their potential to generate infections and zoonosis in humans.

Shrimp farming worldwide is based on a similar technological package, characterized by three phases: Controlled Reproduction, Larvae Culture, and Grow-out Culture. This basic aquaculture package uses broodstock animals, with different levels of fundamental genetic selection, induced to mature and reproduce based on unilateral eyestalk ablation. This review identified ten reproduction-related research subjects that can improve the shrimp industry based on basic scientific knowledge and four levels of application: eyestalk ablation alternatives, larvae production, product protection, and grow-out yield improvement. Species-specificity must be considered in developing biotechnology solutions. Alternatives to eyestalk ablation for controlling ovarian maturation are based on neurotransmitter regulation in Litopenaeus; however, the environmental impact of this approach has to be evaluated. Maturation by RNAi requires further evaluation, and maturation pheromones have not been explored. Sex reversal, hybridization, in vitro fertilization, and seedstock cryopreservation of penaeids require fundamental research. Triploid culture and genetic selection can be applied to some species for product protection; however, for L. vannamei, triploidization is not practical yet.

No abstract

The Caribbean spiny lobster Panulirus argus (Latreille, 1804) is an important species in shallow-water coral reefs and target of the most lucrative fishery in the Caribbean Sea. We explored historical demography in P. argus inferred using single nucleotide polymorphisms (SNPs). We expected an increase in population size of P. argus from Florida, USA starting ~18,000–24,000 years ago, after the Last Glacial Maximum, when ice sheets started to retreat and sub-tropical/tropical shallow coastal waters warmed up. A total of 10 lobsters were collected from shallow reefs in the Florida Keys, Florida, USA. One microgram of gDNA extracted from each specimen was used for RAD library construction using established protocols. A panel of 1643 SNPs obtained after interrogation of RAD-tags was used to calculate a site frequency spectrum (SFS). The observed SFS for the Florida population of P. argus exhibited a non-normal distribution peaking at singleton SNPs. The expected SFS in a total of six different candidate demographic models with dissimilar population size changes through time (i.e., standard neutral, exponential growth, bottleneck, bottleneck + growth, two epochs, and three epochs) were numerically computed in the software ∂a∂i and a model selection approach was implemented to test which expected model(s) best fitted the empirical SFS. The model selection approach indicated that the bottleneck + growth model most closely matched the observed SFS; P. argus experienced a population decline at about 1.9 (0.75–5.7) mya, to then recover and growth exponentially until present time. In disagreement with expectations, population expansion started much earlier than ~18,000–24,000 years ago. Fisheries and conservation studies are expected to profit from the evaluation of genomic and population variability in this species using demographic models, as shown here. Studies exploring population connectivity and locality-specific demographic history of P. argus are underway.