Thais chocolata

Abstract: The first appraisal of butyltin (BT) contamination linked with imposex incidence in Peruvian coastal areas was performed in the present study. Imposex occurrence and BT levels in female bodies were analyzed in the rock snail Thais chocolata distributed along 10 sites in areas under the influence of Callao and Chimbote Harbors. Imposex levels associated to high tributyltin (TBT) concentrations were observed in six of 10 studied sites, and the highest imposex levels were seen in gastropods collected near the harbor terminals. Tributyltin concentrations were the highest reported for gastropod mollusks (up to 662 ng Sn g � 1 ) in recent studies. Although TBT-based antifouling paints have been banned globally (International Maritime Organization, 2008), the combination of high imposex and TBTs level with butyltin degradation index values indicated fresh TBT inputs in these Peruvian coastal areas. Thus, the need to implement local regulatory strategies related to the use of TBT-free antifouling paints is urgent, as is a thorough assessment of the effectiveness of the TBT global ban. Moreover, the wide distribution of T. chocolata combined with its capability to elicit imposex and bioaccumulate BTs renders this a good sentinel species for TBT contamination along the western South American coast. Environ. Toxicol. Chem. 2012;31:955-960. # 2012 SETAC

Abstract: The analysis of density, spatial distribution and gonadic histology of a Thais chocolata population in small bay Punta Arenas (21°38'S-70°09'W), has allowed define certain indicators, which show that the reproductive aggregations would take place in the shallow zone (13-15 m depth) at the same time reported for other populations of this species in northern Chile. The feature that evidence such an event are referred to the aggregated distribution of sexually mature adults in the 13 m and 15 m isobath, a distinct times of the year. Such times are different from these established for the legal veda. Thus, this legal reduction should be restudied in order to protect reproduction of this specie and hence to prevent a potential collapse of the stock in the Regions I and II (18°-26°S), taking into account that the previous fishery in Regions III and IV (26°-32°S) have already collapsed since 1988.

Abstract: El imposex es la superimposicion de pseudopene y vaso deferente en el sistema reproductor de las hembras de gasteropodos. Esta virilizacion se atribuye a un desbalance hormonal inducido por el tributilestano (TBT), un compuesto organoestanoso, presente en las pinturas anti-incrustantes. Este estudio analiza la severidad, proporcion, grados e indices de imposex en una poblacion de Thaisella chocolata de Bahia Caldera, Chile. El sexo se determino por biopsia de la gonada de 180 ejemplares y el imposex por la concurrencia de ovario, glandula de la capsula, vaso deferente y pseudopene en hembras anormales. La proporcion de hembras afectadas se estimo a traves de la formula de Gibbs et al. (1987). Se clasifico el grado del sindrome aplicando cinco escalas y se calcularon los Indices del Estado del Vaso Deferente (VDSI), Longitud Relativa del Pene (RPLI) y Tamano Relativo del Pene (RPSI). Los resultados muestran que el 100% de las hembras de T. chocolata provenientes de Bahia Caldera sufre de imposex. El analisis macroscopico revelo atrofia de la vagina y de las glandulas femeninas. Algunas hembras carecen de glandula ingestiva y receptaculo seminal. Se determino alteraciones citologicas como la modificacion del epitelio interno, ocurrencia de areas acelulares, falta de lamina basal y presencia de nucleo picnotico, y superposicion de tejido prostatico en las tres glandulas femeninas. Las alteraciones anatomicas e histologicas asociadas al imposex determinan la esterilidad absoluta de las hembras. El sindrome alcanzo los grados maximos en todas las escalas aplicadas, excepto en la de Barreiro et al. (2001). Se recomienda el uso del VDSI para T. chocolata, ya que, es una medida realista de la virilizacion y potencial reproductivo de las hembras y no estaria afectado por la forma y tamano del pene.

Abstract: Gastropod mollusks are part of the principal marine resources cultivated and commercialized in Chile. There are native Chilean species such as loco (Concholepas concholepas ), locate (Thais chocolata), trumulco snail (Chorus giganteus), keyhole limpets (Fissurella spp.), tegula snail ( Tegula atra) as well as exotic species such as red abalone ( Haliotis rufescens) and Japanese abalone (Haliotis discus hannai). Despite their importance as marine resources, molecular genetic studies establishing phylogenetic relationships and estimating population genetic parameters are scarce. The aim of this study is to establish a molecular approach among the main commercial gastropod species in Chile. The mitochondrial genes 16S rRNA and COI, and the nuclear ribosomal region ITS1-5.8SrDNA-ITS2 were amplified by PCR and sequencing. Alignment analysis was used to determine systematic relationships at the specific level for the species studied. The results revealed that 7 species are grouped in 4 genetically distinct families (Haliotidae, Trochidae, Muricidae and Fissurellidae). In comparison with COI sequencing, 16S rRNA and ITS1-5.8SrDNA-ITS2 sequencing were relatively more conserved with a divergence percentage for 16S rDNA and ITS1-5.8SrDNA-ITS2 of 1.2% and 1.8%, respectively, contrasting with the value of 10% obtained for COI in abalone.