Abstract The success of Procamallanus (Spirocamallanus) inopinatus infection in fish involves a complexity of variables. This study aims to evaluate the relationship between abundance of P. (S.) inopinatus with biometric and somatic parameters, sex, relative condition factor (Kn) and hosts diet, as well as to evaluate length relationship of the parasites and the hosts. The fishes were collected by the mesh method and data, length, weight, sex, gonad and liver weight, Gonadosomatic index (GSI) and hepatosomatic index (HSI), Kn and stomach content were recorded. Twenty-seven specimens of P. (S.) inopinatus were collected in the intestine from Serrasalmus rhombeus and 52 from Leporinus friderici. In general, the prevalence, mean intensity and mean abundance of infection was higher in L. friderici. The total abundance was explained by the variables GSI, HSI total length, gonad and liver weight. Fish relative condition factor (kn) and sex were not influenced by the infection, being that the parasite infection did not impair the body condition of the hosts. There is no relationship between host length and parasite length in any of the evaluated fish species. On average, S. rhombeus parasites are 0.69 cm larger than L. friderici parasites.

Abstract This study analyzed the parasitism by Clinostomum sp. metacercariae of the neotropical fish Cichlasoma paranaense (Kullander 1983) and environmental variables’ influence on their host-parasite relationship in Central Brazil. Fish were collected in five impoundments (I) from three towns: Itauçú (n = 2), Inhumas (n = 1), and Goiânia (n = 2), Goiás State, Brazil. Ninety-five fish were analyzed, weighted and length measured. Afterward, the presence of metacercariae in the gills, muscles, fins, and body cavities was investigated. The metacercariae were fixed in AFA solution, kept in 70% alcohol, and stained with carmine. The infection prevalence revealed that 0.64, 0.56 and 0.91% of fish was infected. The abundance was 4.14, 3.22 and 5.88, with a mean intensity of 6.44, 5.80 and 6.42 per impoundment (I 13, I 15 and I 16), respectively. The frequency of metacercariae was higher in fish collected in Goiânia. High frequency of parasites was observed in the gills, muscles, and fins. The limnological variables did not present direct interference in the parasitism. The fish’ standard length influenced the number of metacercariae positively but did not differ to the relative condition coefficient.

Abstract Plant-derived molluscicides have been indicated as biodegradable and low-cost strategies for control of Biomphalaria spp., intermediate host for the Schistosoma. This study evaluated whether the crude ethanolic extract of the Persea americana stem bark has molluscicidal activity against embryos, newly-hatched and adults of Biomphalaria glabrata. The extract was obtained, characterized and its toxicity analyzed by snail embryotoxicity test (144 h) and acute toxicity test with newly-hatching and adult snails (96 h). Results showed the presence of flavonoids, anthraquinone heterosides, coumarins and tannins in the crude ethanolic extract, which showed molluscicidal activity against all life cycle stages of B. glabrata. The LC50 for embryos, newly-hatched and adults were 27.06, 30.60 and 55.55 ppm, respectively. Embryos exposed to the extract at 50 ppm showed hatching inhibition and at 6.2 and 25 ppm had the highest rates of morphological alterations, such as shell malformations and coagulation of the perivitelline substance. Adult snails exposed to the extract at 75 ppm showed a peak of behavioral changes, such as lethargy and shell reclusion, in addition to answers like hemolymph release in most concentrations. Further studies are required, prioritizing toxicity testing on non-target organisms and further elucidation of the active molecules.

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.

Os apectos morfofuncionais da oogênese do Poecilia vivipara foram estudados nesse trabalho. Esse estudo contribuiu para o aprimoramento das informações sobre a biologia reprodutiva e do desenvolvimento de espécies com fecundação interna, em especial aquelas pertencentes à família Poecilidae. Para tanto, caracterizou-se os estágios de maturação gonadal e desenvolvimento folicular através de análises mesoscópicas, histológicas, histoquímicas e citoquímicas com lectinas. O estudo mesoscópico permitiu a classificação do desenvolvimento ovariano em seis estágios: imaturo, em maturação I, em maturação II, maturo I, maturo II e pós-desova. O exame microscópico dos ovários permitiu a identificação dos oócitos pré-vitelogênicos (OPVt) e vitelogênicos (OVt). Na fase pré-vitelogênese, verificou-se os oócitos tipo I (OI) e tipo II (OII), e na fase vitelogênese, foram encontrados oócitos tipo III (OIII), tipo IV (OIV) e os pós-fertilização (OV). Com o avanço da oogênese, o citosol dos oócitos aumentaram em volume, com crescente acúmulo de grânulos citoplasmáticos, caracterizando a vitelogênese. Além disso, a zona radiata (ZR) aumentou de espessura e alterou suas características histo-citoquímicas, e o epitélio folicular (EF), inicialmente delgado e constituído por células pavimentosas, nos FOs na fase III tornaram-se cúbico simples. As análises histoquímicas e citoquímicas permitiram diagnosticar alterações na composição molecular das estruturas que formam os FOs ao longo do desenvolvimento gonadal. O presente estudo indica diferenças no sistema reprodutor feminino entre espécies de peixes com fecundação interna e aquelas com fecundação externa e sugere que o P. vivipara pode ser usado como modelo experimental em testes de toxicidade ambiental.

The morphofunctional aspects of oogenesis of Poecilia vivipara were studied aiming to understand the reproductive biology and development of species with internal fertilization, particularly those belonging to the family Poeciliidae. The stages of gonadal maturation and follicular development were characterized using mesoscopic, histological, histochemical, and lectin cytochemical analyses. Through mesoscopic evaluation the ovarian development was classified in six phases of development: immature, in maturation I, in maturation II, mature I, mature II, and post-spawn. Based on microscopic examination of the ovaries, we identified the presence of oocytes types I and II during the previtellogenic phase and types III, IV, and V during the vitellogenic phase. As oogenesis proceeded the oocyte cytosol increased in volume and presented increased cytoplasmic granule accumulation, characterizing vitellogenesis. The zona radiata (ZR) increased in thickness and complexity, and the follicular epithelium, which was initially thin and consisting of pavimentous cells, in type III oocytes exhibited cubic simple cells. The histochemical and cytochemical analyses revealed alterations in the composition of the molecular structures that form the ovarian follicle throughout the gonadal development. Our study demonstrated differences in the female reproductive system among fish species with internal and external fertilization and we suggest P. vivipara can be used as experimental model to test environmental toxicity.

The present study evaluated and characterized the different phases of development and the cell types present in the gill epithelium of embryos, larvae, and fingerlings of guppy (Poecilia vivipara Bloch & Schneider, 1801) specimens exposed to water with salinity ranging from 0‰ to 20‰. The development of P. vivipara was classified into eight phases. The yolk was intensely eosinophilic, with glycidic and lipidic components between phases 1 to 7. After the development of their branchial epithelium, the presence of pavement cells, mitochondria-rich cells, and mucous cells (MCs) was observed. The understanding of ontogenesis indicates the sequence of cellular origin. Only type IV MCs located in the gill rays was detected from phase 3 through phase 7. Other types of MCs were observed only when the fingerlings were exposed to salinity changes and showed to be lectin-reactive, thus indicating that P. vivipara modulates the cellular behavior when submitted to salinity changes. Exposure to variable saline concentrations did not interfere in the initial development of guppies. The presence of a yolk sac until the fingerling phase characterized this species as ovoviviparous.