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White spot syndrome virus (WSSV) is the causative agent of white spot syndrome, one of the most devastating diseases in shrimp aquaculture. The genome of WSSV includes a gene that encodes a putative family B DNA polymerase (ORF514), which is 16% identical in amino acid sequence to the Herpes virus 1 DNA polymerase. The aim of this work was to demonstrate the activity of the WSSV ORF514-encoded protein as a DNA polymerase and hence a putative antiviral target. A 3.5 kbp fragment encoding the conserved polymerase and exonuclease domains of ORF514 was overexpressed in bacteria. The recombinant protein showed polymerase activity but with very low level of processivity. Molecular modeling of the catalytic protein core encoded in ORF514 revealed a canonical polymerase fold. Amino acid sequence alignments of ORF514 indicate the presence of a putative PIP box, suggesting that the encoded putative DNA polymerase may use a host processivity factor for optimal activity. We postulate that WSSV ORF514 encodes a bona fide DNA polymerase that requires accessory proteins for activity and maybe target for drugs or compounds that inhibit viral DNA replication.

Proliferating cell nuclear antigen (PCNA), a member of the sliding clamp family of proteins, interacts specifically with DNA replication and repair proteins through a small peptide motif called the PCNA-interacting protein or PIP box. PCNA is recognized as one of the key proteins involved in DNA metabolism. In the present study, the recombinant PCNA from Litopenaeus vannamei (LvPCNA) was heterologously overexpressed and purified using metal ion-affinity chromatography. Crystals suitable for diffraction grew overnight using the hanging-drop vapour-diffusion method. LvPCNA crystals belong to space group C2 with unit-cell parameters a=144.6, b=83.4, c=74.3 Å, β=117.6°. One data set was processed to 3 Å resolution, with an overall Rmeas of 0.09 and a completeness of 93.3%. Initial phases were obtained by molecular replacement using a homology model of LvPCNA as the search model. Refinement and structural analysis are underway. This report is the first successful crystallographic analysis of a marine crustacean decapod shrimp (L. vannamei) proliferating cell nuclear antigen.

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A pesar de la importancia económica que representa la cabrilla arenera, Paralabrax maculatofasciatus, la información acerca de sus aspectos reproductivos es escasa, por lo que se investigó su biología reproductiva así como su composición proximal de la gónada. Para ello, se capturaron 30 organismos mensualmente de marzo 2017 a febrero 2018. Los peces se midieron, pesaron y disectaron para obtener el factor de condición (K), el índice hepatosomático (IHS) y el índice gonadosomático (IGS). Adicionalmente, se preservó tejido de gónada para llevar a cabo el proceso histológico y la tinción hematoxilina-eosina. Los resultados indicaron que el IHS y el IGS fueron afectados significativamente (P<0.05). El análisis histológico evidenció la presencia de machos maduros en abril, así como de octubre a noviembre, y para las hembras, se observó la presencia de organismos desarrollados en abril y de octubre a diciembre. Adicionalmente, se detectó la presencia de organismos en transición de hembra a macho. El análisis proximal mostró el valor máximo de grasa en abril, lo cual coincidió con el menor valor de humedad. El análisis de proporción mostró una significativa dominancia de machos. Los datos obtenidos en la presente investigación coadyuvarán en la implementación de programas de protección para la especie.ABSTRACTDespite the economic importance of sand bass, Paralabrax maculatofasciatus, little information regarding its reproductive aspects is known. In this study, gonadal maturity stage, biological indexes, proximate gonad composition and sex ratio proportion were determined. A total of 30 wild spotted sand bass were monthly obtained from March 2017 to February 2018. Organisms were measured, weighted and dissected in order to obtain the condition factor (K), hepatosomatic index (IHS) and gonadosomatic index (IGS). A small portion of gonad was preserved to perform the histological procedure, and stained with Harris´ hematoxilineosin technique. The results indicate that somatic indexes were significantly affected (P<0.05) in terms of IHS and IGS. Histological analysis showed the presence of ripe males in April and from October to November, and for females, the presence of developed organisms was observed in April and from October to December. Additionally, the presence of transitional organisms from female to male was observed. The proximate analysis showed the maximum crude fat value in April, which coincides with the lowest moisture value. Sex proportion showed a significant male dominance. These data provide valuable information for the development of protection programs to encourage a sustainable fishery of the species.

Palaemonetes argentinus, an abundant freshwater prawn species in the northern and central region of Argentina, has been used as a bioindicator of environmental pollutants as it displays a very high sensitivity to pollutants exposure. Despite their extraordinary ecological relevance, a lack of genomic information has hindered a more thorough understanding of the molecular mechanisms potentially involved in detoxification processes of this species. Thus, transcriptomic profiling studies represent a promising approach to overcome the limitations imposed by the lack of extensive genomic resources for P. argentinus, and may improve the understanding of its physiological and molecular response triggered by pollutants. This work represents the first comprehensive transcriptome-based characterization of the non-model species P. argentinus to generate functional genomic annotations and provides valuable resources for future genetic studies. Trinity de novo assembly consisted of 24,738 transcripts with high representation of detoxification (phase I and II), anti-oxidation, osmoregulation pathways and DNA replication and bioenergetics. This crustacean transcriptome provides valuable molecular information about detoxification and biochemical processes that could be applied as biomarkers in further ecotoxicology studies.