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Peroxiredoxin 5 (PRDX5) is a mammalian thioredoxin peroxidase ubiquitously expressed in tissues. Its role as antioxidant enzyme has been previously supported in different pathological situations. In this study, we determined the complete human PRDX5 genomic organization and isolated the 5'-flanking region of the gene. Human PRDX5 gene is composed of six exons and five introns similarly to other chordate PRDX5 genes. Several single nucleotide polymorphisms were identified. Six out of them have amino acid substitutions in protein-coding region. Analysis of the 5'-flanking region of human PRDX5 revealed the presence of a TATA-less promoter containing a canonical CpG island and several putative response elements for transcription factors. To analyze the regulatory mechanisms controlling human PRDX5 expression, we characterized the 5'-flanking region by cloning various segments of this region in front of a luciferase reporter sequence. Transfection in HepG2 cells indicate that the 5'-flanking region contains regulatory elements for constitutive expression of human PRDX5. Multiple transcription start sites were also identified by 5'-RACE-PCR in human liver. Moreover, although no corresponding proteins were reported, we present new alternative splicing variants encoded specifically by human PRDX5 gene. The characterization of human PRDX5 gene revealed the complexity of its regulation and a high variability of sequences that might be associated with pathological situations.

Little is known about the biology of Burmeister’s porpoises (Phocoena spinipinnis), a small cetacean species endemic to South American waters. Information on stock structure, however, is urgently needed, as the species suffers from considerable mortality due to local fishery activities throughout its distribution range. Using mitochondrial control region sequences and 11 species-specific microsatellite loci, we assessed the genetic differentiation among 118 stranded, incidentally or directly-caught Burmeister’s porpoises from different localities in Peruvian, Chilean, and Argentine waters. F-statistics and Bayesian clustering analyses indicate a major population differentiation along the South American Pacific coast, separating Peruvian from both Chilean and Argentine individuals. Interestingly, this population boundary is consistent with the population structure found in another sympatrically-occurring cetacean species: the dusky dolphin (Lagenorhynchus obscurus). Given that vulnerability to local depletion for South American coastal porpoises and dolphins is probably highest in the Peruvian population (due to high exploitation levels and recurrent El Niño events), the genetic data reported here considerably strengthen the need for conservation efforts focused on regulation of catches in local waters. Moreover, we discuss possible genetic differentiation among Burmeister’s porpoises (i) from the Atlantic and Pacific Ocean and (ii) from different Peruvian harbors. Finally, cross-species amplifications suggest that our newly-developed microsatellite markers will be useful in population genetic studies in the five other extant porpoise species.