Molecular and taxonomic characterisation of introduced specimens of Poecilia reticulata in the lower Paraguay River basin (Cyprinodontiformes: Poeciliidae)

Poeciliids comprise around 300 species inhabiting the fresh and brackish waters of the Americas and Africa. Poecilia reticulata is native to Northeastern South America and Trinidad and Tobago. In this paper, introduced specimens of P. reticulata collected in the lower Paraguay River in Argentina, were characterized by means of molecular and taxonomic approaches. We further explore, by means of DNA Barcoding, the singularity of the genetic identity of these specimens. Ocurrence of P. reticulata in the lower Paraguay River represents the first record of this species in Argentina. Thirteen individuals of P. reticulata were collected. DNA barcoding showed that all five specimens sampled belong to a single mitochondrial lineage, which was also present in 11 countries from five continents. The distance-based tree clearly grouped separetely four different clusters of P. reticulata when including public data. Genetic distance between the most divergent P. reticulata almost paralleled distance between this species and Poecilia mexicana and P. vivipara. Established populations from Paraguay could be one of the plausible sources for the introduced populations recorded in the lower Paraguay River. The presence of P. reticulata in an open waterway with known drainage to a natural stream is of major concern.(AU)

Poecilídeos compreendem cerca de 300 espécies que habitam águas doces e salobras das Américas e África. Poecilia reticulata é nativa do nordeste da América do Sul e Trinidad e Tobago. Neste trabalho, espécimes introduzidos de P. reticulata coletados no baixo rio Paraguai na Argentina, foram caracterizados por meio de abordagens moleculares e taxonômicas. Exploramos ainda, por meio de DNA Barcoding, a singularidade da identidade genética destes espécimes. A ocorrência de P. reticulata no baixo rio Paraguai representa o primeiro registro dessa especie na Argentina. Treze indivíduos de P. reticulata foram coletados. O Barcoding mostrou que todos os espécimes pertencem a uma única linhagem mitocondrial, a qual está presente em 11 países dos cinco continentes. A árvore de distâncias agrupou separadamente quatro clusters diferentes de P. reticulata quando incluindo dados públicos. A distância genética entre os agrupamentos mais divergentes de P. reticulata quase igualou a distância entre esta espécie e Poecilia mexicana e P. vivipara. As populações estabelecidas no Paraguai poderiam ser uma das fontes plausíveis para as populações introduzidas registradas no baixo rio Paraguai. A presença de P. reticulata em um canal aberto com drenagem conhecida para um córrego natural é de grande preocupação.(AU)

Influence of environmental integrity on feeding, condition and reproduction of Phalloceros harpagos Lucinda, 2008 in the Tarumã stream micro-basin / Influência da integridade ambiental na alimentação, condição e reprodução de Phalloceros harpagos Lucinda, 2008 na microbacia do córrego Tarumã

With the objective of evaluating the influence of the environmental integrity on feeding, condition factor and reproduction of Phalloceros harpagos, the species biology was analyzed in the Tarumã Stream micro-basin, Naviraí, Mato Grosso do Sul State (upper Paraná river). Samples were collected from 2007 to 2010, and biometric data of specimens was registered. Stomach and gonad were taken for the analysis of feeding and reproduction, respectively. The species is detritivore, showing a high flexibility in the diet. Debris and sediment, followed by plant and algae were the most ingested items. As for the condition factor, no definite pattern was observed in the values for both sexes, probably because the species has a long reproductive period. The frequency of occurrence distribution of gonad maturity stages indicated a greater number of immature females in the dry season at one of the least impacted sites. On the other hand, in the most affected site females were observed with increased fecundity. From the results obtained, it was found that the different levels of environmental degradation have no significant influence on feeding and condition factor, but rather probably exert influence on the reproduction of the species.

Com o objetivo de avaliar a influência da integridade ambiental na alimentação, fator de condição e reprodução de Phalloceros harpagos a biologia da espécie foi analisada na microbacia do córrego Tarumã, Alto Rio Paraná. As coletas foram realizadas de 2007 a 2010 e os exemplares tiveram as suas informações biométricas anotadas. Foram retirados os estômagos e as gônadas para as análises da alimentação e reprodução, respectivamente. A espécie é detritívora e apresentou alta flexibilidade na dieta, sendo detritos/sedimento, seguido por vegetais e algas, os itens ingeridos em maior quantidade. Quanto ao fator de condição, não foi observado um padrão sazonal ou espacial nos valores encontrados para ambos os sexos, provavelmente devido ao fato da espécie apresentar um prolongado período reprodutivo. A distribuição de frequência de ocorrência de estágios de maturação gonadal indicou maior quantidade de fêmeas imaturas durante a estação seca em um dos locais menos impactados. Por outro lado, no local mais impactado foram observadas fêmeas com maior fecundidade. A partir dos resultados obtidos, foi verificado que os diferentes estados de degradação ambiental não possuem influência significativa sobre a alimentação e fator de condição, mas, provavelmente, exerceram influência sobre a reprodução da espécie.

Norethindrone-induced masculinization and progeny testing in guppy, Poecilia reticulata (Peters 1859).

Norethindrone(NE) was evaluated for its efficacy on alteration of sex ratio of P. reticulata. Either the young fry or the brooders and the resultant fry were fed a commercial diet incorporated with NE at 0, 25, 50, 75 and 100 mg kg-1 diet (ppm) for 30-40 d in rectangular glass aquaria; this was followed by 40-60 d rearing on NE-free diet in out-door concrete tanks. In general, the androgen treatment altered sex ratio, leading to the production of a dose dependent increase in the percentage of males. The oral administration of the steroid at 75 ppm for 40 d or 100 ppmfor 30 or 40 d to first feeding fry, yielded 100% males. On the other hand, NE administration to brooders before parturition and the resultant fry also produced an all-male population of guppy. The sex ratio of the untreated control was almost 1:1. The survival of fish in all the trials was high, ranging between 67 and 100%. Mating masculinized males (“XX” male) with normal female resulted in an all-female progeny, while crossing normal male (XY) from treatment groups with normal female sired normal sex ratio (1:1), elucidating XX-XY sex determination system in the guppy.

Pseudobrânquia do guaru Poecilia reticulata (Peter, 1859): análise estrutural, morfométrica e histoquímica para detecção de glicoconjugados / Pseudo-gill of guppy, Poecilia reticulata (Peter, 1859): structural, morphometric, and histochemical analyses for the detection of glycoconjugates

A morfologia, os parâmetros citomorfométricos e os glicoconjugados presentes na pseudobrânquia de guaru, Poecilia reticulata Peter, 1859 (Cyprinodontiformes: Poeciliidae), foram investigados por microscopia de luz acoplada ao sistema de captura e análise de imagens, juntamente por histoquímica com lectinas. A anatomia microscópica indicou que P. reticulata possui pseudobrânquia glandular formada por dois lóbulos, a qual se localiza abaixo do epitélio faringiano. O órgão é constituído por parênquima vascularizado e rico em células pseudobranquiais. Esse tipo celular exibe estado citofisiológico ativo, com abundante sistema de biomembranas e ausência de óstio na superfície apical,que por sua vez é encontrado nas células ricas em mitocôndrias das holobrânquias. Assim, indica-se que as células da pseudobrânquia se distinguem das células das holobrânquias em relação à morfologia, histoquímica e fisiologia. Em decorrência dessas características intrínsecas, a pseudobrânquia de alevinos do guaru pode desempenhar funções não respiratórias nas fases iniciais do desenvolvimento. Além disso, a caracterização da pseudobrânquia do guaru possibilitará estudos futuros sobre o efeito de poluentes aquáticos em espécies biomonitoras, como P. reticulata.

The morphology, cytomorphometric parameters, and glycoconjugates present in the pseudo-gill of guppy, Poecilia reticulata Peter, 1859 (Cyprinodontiformes: Poeciliidae), were investigated by light microscopy coupled to image capture and analysis system, and also by lectin histochemistry. The microscopic anatomy indicates that P. reticulata has a glandular pseudo-gill formed by two lobes, located underneath the pharynx epithelium. The organ is formed by vascularized parenchyma rich in pseudo-gill cells. This cell type exhibits active cytophysiological state with an abundant system of biomembranes and lacking of ostium in apical surface, which in turn is found in the mitochondria-rich cells of the holobranch. This indicates that the pseudo-gill cells distinguishe from the holobranch cells in their morphology, histochemistry and physiology. Due to these intrinsic characteristics, the pseudo-gill of guppy fingerlings may have non-respiratory function in the initial phase of their development. The characterization of guppy's pseudo-gill could facilitate further studies about the effect of water pollutants on biomonitor species, such as P. reticulata.

Effects of methyltestosterone, tamoxifen, genistein and Basella alba extract on masculinization of guppy (Poecilia reticulata).

The effects of different anti-estrogenic chemicals were evaluated in guppy, Poecilia reticulata on sex differentiation and survival. New-born fry of the fish were fed diets containing genistein (1 gm kg-1), tamoxifen (100 mg kg-1), methanol extract of Basella alba (1 gm kg-1) and 17α-methyltestosterone (60 mg kg-1) for 30 days. The treated groups showed no significant difference (P>0.05) in survival percentage while a significant increase (P<0.05) in percentage of males were observed in all the treatment groups compared to that in control. Control fish showed the lowest percentage (44.49%) of males while 17α-methyltestosterone treatment provided maximum (81.90%) males, followed by tamoxifen (80.09%), genistein (70.59%) and B. alba (63.55%). Intersex fish with male like colouration and gonopodium development, but female gonad structure was observed in all the treated groups. The nonsteroidal compounds evaluated in this study showed potential for affecting sex ratios although their potency was lower compared to 17α-methyltestosterone. Further studies are needed to determine an optimum treatment regime with these agents for induction of 100% sex reversal in guppy.

Upstream guppies (Poecilia reticulata, Peters, 1859) go against the flow / Gupies (Poecilia reticulata, Peters, 1859) de áreas de cabeceira se posicionam contra a corrente

Guppies (Poecilia reticulata Peters 1859) in lakes and from captive-bred populations are predicted to show little rheotaxis compared to conspecifics in a stream environment that are regularly exposed to flash floods associated with involuntary downstream migration. Here we test this hypothesis using an artificial stream, examining guppies of two wild riverine populations, one lake population, and one ornamental strain. Guppies from the most upstream riverine habitat show the most pronounced rheotaxis and are less likely to be swept downstream during flooding events. However, there is no significant difference between guppies from the lowland riverine habitat, the Pitch Lake and ornamental strain. We propose that station-keeping behaviours are most strongly selected in the upstream population because large spatial differences exist in ecology and environment between up- and downstream habitats. Given that these sites are separated by barrier waterfalls that prevent compensatory upstream migration, natural selection operates particularly strong against upstream guppies that have been displaced downstream during flooding events.

Populações de guppies (Poecilia reticulata Peters) que vivem em lagos e em cativeiro podem demonstrar menos reotaxia em comparação com populações que habitam rios e que estão frequentemente expostas a enchentes e que provocam a migração involuntária para jusante. Neste trabalho, vamos testar esta hipótese num rio artificial utilizando guppies de duas populações selvagens que habitam em rios, uma população que habita em lagos, e uma linhagem ornamental. Os resultados demonstram que os guppies de rios que provêm de localidades a montante demonstram maior reotaxia, diminuindo assim probabilidade de serem arrastados para jusante em períodos de enchentes. No entanto, não foram encontradas diferenças significativas entre guppies de localidades a jusante, do lago Pitch ou ornamentais. Este resultado pode dever-se ao facto de existirem grandes diferenças ecológicas entre os habitats localizados a jusante e a montante dos rios. Devido ao facto de estas localidades estarem separadas por cachoeiras, impossibilitando a migração rio-acima, a seleção natural poderá estar a actuar contra guppies que sejam arrastados rio abaixo durantes os períodos de cheias.

Adaptation of the gill epithelium of an euryhaline fish, the guppy (Poecilia vivipara), to freshwater / Adaptação do epitélio branquial de peixes eurialinos, guaru (Poecilia vivipara), para água doce

The south-american euryhaline fish Poecilia vivipara (BLOCH; SNEIDER, 1801), the guppy, is found both in estuary and river waters, which suggests high adaptability to environments of different salinity. In this work we studied the adaptation of the interlamellar, bars and rakers epithelia of the gills of estuary fish to freshwater conditions. The results reveal that the gill epithelia of Poecilia vivipara can adjust itself to freshwater by decreasing the VP of mucous cells of the interlamellar epithelium and increase the volumetric proportion (VP) of chloride cells. However, there was no evidence of similar morphological alteration in the rakers region. The epithelia of the rakers appears to be part of a different compartment that is less sensitive to variation of salinity.

O peixe eurihalino sul-americano Poecilia vivipara (BLOCH; SNEIDER, 1801), o guppy, é encontrado tanto em estuários quanto em águas de rios, o que sugere uma alta adaptabilidade aos diferentes ambientes de salinidade. Neste trabalho, estudamos a adaptação do epitélio interlamelar, do arco e do rastelo das brânquias dos peixes de estuário de água doce. Os resultados revelam que o epitélio branquial de Poecilia vivipara pode ajustar-se à água doce, diminuindo a proporção volumétrica (PV) de células mucosas do epitélio interlamelar e aumentando a PV de células clorídricas. No entanto, não houve nenhuma evidência de alteração morfológica semelhante na região do rastelo branquial. O epitélio do rastelo branquial parece ser parte de um compartimento diferente que é menos sensível a variações de salinidade.

Efecto anabólico y androgénico del esteroide acetato de trembolona en el guppy (Poecilia reticulata) / Anabolic and androgenic effect of steroid trenbolone acetate on guppy (Poecilia reticulata)

The effect of semi-synthetic steroid trenbolone acetate (TBA) on the ornamental fish Poecilia reticulata (guppy) was studied. The steroid at a dose of 300 mg/kg feed was administered to 30 days old juvenile specimens during 60 days. Forty days after treatment was ended, an evaluation aimed to determine the steroid residual effect was undertaken. Survival, masculinization ratio and the drug anabolic effect were analyzed. Results showed TBA to be effective to induce masculinization, differing (P < 0.001) with the control group, which registered 32% males and 68% females. TBA turned out to be an excellent anabolic as well, since treated fish showed weight increase, a larger body and an increased size of caudal fin. The steroid did not cause any damage on the treated population. The survival factor was 93.3% for the treated fish as compared to 83% for the control group.

Se investigó el efecto del esteroide semisintético acetato de trembolona (ATB) en el pez de ornato Poecilia reticulata (guppy). Especímenes juveniles de 30 días de edad fueron tratados con el esteroide a dosis de 300 mg/kg de alimento durante 60 días. Al término del tratamiento, 40 días después, se estimó el efecto residual del esteroide. Se analizó la sobrevivencia, la proporción de peces masculinizados, así como el efecto anabólico. Los resultados indicaron que el ATB es eficaz para inducir la masculinización, a diferencia del grupo testigo, donde se registraron 32% de machos. Asimismo, el ATB tuvo un efecto anabólico, ya que los peces tratados mostraron mayor peso y talla e incremento de la aleta caudal. El esteroide no causó daño en la población tratada, al sobrevivir 93.3% de los peces, comparado con 83% del grupo testigo.

Relationship Between Chromatogram Retention Index and Toxicity of Chlorinated Phenols and Chlorinated Benzenes to Guppy / 环境与健康杂志

Objective To study the action of chromatogram retention index in forecasting the LC50 of chlorinated phenols and chlorinated benzenes for the Guppy.Methods Chromatogram retention time of chlorinated phenols and chlorinated benzenes were determined,and the LC50 for Guppy was from the published data.Results A regression model was established,for chlorinated phenols,it was lg(LC50)=1.599-2.64?10-3I,r=0.970,P