ABSTRACT
In recent decades, Brazilian hydroelectric reservoirs have been stocked with hundreds of millions of juvenile migratory fish, but almost no research on stocking has been conducted. In order to study stocking it is essential to tag the fish to be stocked. In this investigation we determined handling-induced mortality, tag retention rate, and absolute growth rate of hatchery-reared juvenile curimbatá (Prochilodus lineatus) tagged with coded wire tags (CWT), a tag widely used on stocked fish. We injected CWT into the dorsal musculature just below the first dorsal fin ray. Despite the need for frequent tag injector maintenance, this tagging location proved to be suitable for tagging juvenile curimbatá. We found no short-term mortality of juvenile curimbatá handled for CWT tagging, high retention rate for CWT (≥ 98.2%) even after 174 d of tagging, and no influence on absolute growth rate by CWT. We conclude that CWT is effective at tagging juvenile curimbatá, and we expect that it will also be effective for many other Brazilian fish species used for stocking.
Nas últimas décadas, reservatórios de hidrelétricas do Brasil foram estocados com centenas de milhões de jovens peixes migradores, mas quase nenhuma pesquisa sobre a estocagem foi conduzida. Para estudo da estocagem, etiquetar os peixes a serem estocados é essencial. Neste estudo, nós determinamos a mortalidade devido ao manejo, taxa de retenção da marca e taxa de crescimento absoluto de juvenis de curimbatá de cativeiro (Prochilodus lineatus) marcados com 'coded wire tag' (CWT), etiqueta amplamente utilizada em peixes estocados. Nós injetamos o CWT na musculatura dorsal logo abaixo do primeiro raio da nadadeira dorsal. Apesar de exigir manutenção frequente do injetor de CWT, esse local mostrou ser apropriado para a marcação de jovens de curimbatá. Não houve mortalidade de curto prazo nos juvenis manejados para marcação com CWT, a taxa de retenção do CWT foi elevada (≥ 98,2%), mesmo após 174 dias da marcação. Além disso, o CWT não influenciou na taxa de crescimento absoluto dos peixes etiquetados. O CWT mostrou ser efetivo para marcar juvenis de curimbatá, e acreditamos que ele também o será para muitas outras espécies de peixes brasileiros utilizadas em estocagem.
Subject(s)
Animals , Characiformes/anatomy & histology , Characiformes/growth & development , Population GrowthABSTRACT
Clostridium perfringens phospholipase C (Cp-PLC), also called alpha-toxin, is encoded by the plc gene and has been implicated in several diseases; however, only a few studies have described polymorphisms in this gene. The aim of this study was to analyze polymorphisms in the Cp-PLC nucleotide and amino acid sequences obtained from isolates from different regions and to compare them to Clostridium phospholipase C sequences deposited in the NCBI database. Environmental samples (sediment, poultry feed, sawdust) and stool samples (from poultry, bovine, swine, horse, caprine, bird, dog, rabbit, toucan) were collected from healthy and sick animals. A total of 73 isolates were analyzed with the majority of samples belonging to the toxin type A subtype and possessing the gene encoding for the beta-2 toxin. Comparison of plc gene sequences from respective isolates revealed a high genetic diversity in the nucleotide sequences of mature Cp-PLC. Sequence comparisons identified 30 amino acid substitutions and 34 isoforms including some isoforms with substitutions in amino acids critical to toxin function. Comparison of sequences obtained in this study to Cp-PLC sequences obtained from the NCBI database resulted in the identification of 11 common haplotypes and 22 new isoforms. Phylogenetic analysis of phospholipase C sequences obtained from other Clostridium species identified relationships previously described. This report describes a broad characterization of the genetic diversity in the C. perfringens plc gene resulting in the identification of various isoforms. A better understanding of sequences encoding phospholipase C isoforms may reveal changes associated with protein function and C. perfringens virulence.
