ABSTRACT
The yellow head virus (YHV) has been reported to be one of most pathogenic viruses for cultivated shrimp; however, serious problems have only been reported in farms in south and southeastern Asian. Recently, a YHV strain was detected in Litopenaeus vannamei cultivated in Mexican farms that lacked virus-associated mortalities or epizooties, and the animals were apparently healthy. The identity of the virus was confirmed by sequencing replicative and structural protein-encoding regions and comparing with homologous virus sequences. Phylogenic relationships and genetic distances were also determined and, although some differences were observed, an influence on virulence was uncertain. In addition, the expression levels of several transcripts (3CLPRO, POL, GP64 and GP116) were evaluated by quantitative real-time polymerase chain reaction during an experimental infection. Although the transcript showed varying kinetics, viral genes were expressed in infected L. vannamei, demonstrating the replicative capability of this YHV strain.
ABSTRACT
Mitochondria play key roles in many cellular processes. Description of penaeid shrimp genes, including mitochondrial genomes are fairly recent and some are focusing on commercially important shrimp as the Pacific shrimp Litopenaeus vannamei that is being used for aquaculture not only in America, but also in Asia. Much less is known about other Pacific shrimp such as the yellowleg shrimp Farfantepenaeus californiensis and the blue shrimp Litopenaeus stylirostris. We report the complete mitogenomes from these last two Pacific shrimp species. Long DNA fragments were obtained by PCR and then used to get internal fragments for sequencing. The complete F. californiensis and L. stylirostris mtDNAs are 15,975 and 15,988 bp long, containing the 37 common sequences and a control region of 990 and 999 bp, respectively. The gene order is identical to that of the tiger shrimp Penaeus monodon. Secondary structures for the 22 tRNAs are proposed and phylogenetic relationships for selected complete crustacean mitogenomes are included. Phylogenomic relationships among five shrimp show strong statistical support for the monophyly of the genus across the analysis. Litopenaeus species define a clade, with close relationship to Farfantepenaeus, and both clade with the sister group of Penaeus and Fenneropenaeus.
ABSTRACT
We present 10 microsatellite markers for the buttonwood mangrove, Conocarpus erectus, a wide-range mangrove associate species. Polymorphism was assessed among individuals from six different populations along the Pacific Coast of Mexico and Costa Rica, as well as in two individuals from the Yucatan Peninsula in the Atlantic. The number of alleles detected in the Pacific ranged from two to five. All loci amplified in the Yucatan samples and seven loci revealed a unique Atlantic allele. These markers will be useful for studies in the conservation of the species and to study the basic biology of C. erectus.
ABSTRACT
Starch gel electrophoresis was used to analyze the allelic variability of four polymorphic loci (Lap-2, Lap-3, Pgm and Gpi) from a single population of Artemia franciscana (Kellogg, 1906) from the Great Salt Lake (Utah, USA), cultured under eight different experimental conditions. The organisms were cultured to the adult stage under a 2 x 2 x 2 experimental design (22 and 30 degrees C; 30 and 60 ppt salinity; and Dunaliella sp. and Spirulina sp. as food). There were significant differences in allele frequencies at each locus and the mean expected heterozygosity (He) varied from 0.236 to 0.447. Therefore, the hypothesis of no allelic differences among treatments is rejected. With relation to a possible correlation between genetic variability and the phenotypic characteristics, the results show that there is probably a synergic effect between the different salinities and temperatures on the survival of heterozygous organisms in the different loci.
