Transferability of heterologous primers in Brycon falcatus

The genus Bryconcomprises fish species of significant socioeconomic and biological importance in Brazil. Despite that, the genetic knowledge about these species is scarce, especially regardingBrycon falcatus. Thus, the objective of this study was to evaluate the transferability of heterologous microsatellite primers inB. falcatus for the first time. Heterologous primers obtained from B. opalinus, B. hilarii, B. insignis, B. orbignyanus, B. amazonicus, Prochilodus argenteus, Prochilodus lineatus, Piaractus mesopotamicus, and Colossoma macropomum were evaluated. The primers that showed the best amplification patterns were applied to a sample of 22 individuals and the genetic parameters were calculated. Nine primers displayed satisfactory cross-amplification withB. falcatus: BoM5 (Brycon opalinus); Bh8, Bh13 and Bh16 (B. hilarii); Borg59 (B. orbignyanus); Bag22 (B. amazonicus); Par12 and Par80 (P. argenteus), and Cm1A8 (C. macropomum). The genetic parameters (number of alleles, effective alleles, allele richness, and expected and observed heterozygosity) and the polymorphic information content (PIC) confirmed the viability of these primers for population genetics analyses. Our study demonstrates the potential of transferability of microsatellite markers from related species and even different genera to B. falcatus, providing usefull tools for future population genetic studies in this species. (AU)

Effects of dietary supplementation with a microalga (Schizochytrium sp.) on the hemato-immunological, and intestinal histological parameters and gut microbiota of Nile tilapia in net cages.

Nutritional improvements in intensive aquaculture production systems is necessary for the reduction of stress, maximum utilization of nutritional components, and expression of the genetic potential of fish. The objective of this study was to evaluate the hemato-immunological, and histological parameters and gut microbiota of Nile tilapia fed with the microalga Schizochytrium sp. Males of Nile tilapia were distributed among eight net cages (6 m3), and fed for 105 days with two diets: control (CON), without Schizochytrium sp., and supplemented (SUP), with 1.2% Schizochytrium sp. in the diet. The final weight, mortality, hematocrit, total erythrocyte count (RBC), hemoglobin, hematimetric indices, white blood cell count (WBC), total protein, and serum lysozyme were measured. Alterations in intestinal morphology were evaluated. The gut microbiota was evaluated with next-generation sequencing. No significant differences (p>0.05) were found in the final weight and mortality between diets. Regarding the hematological parameters, a difference (p<0.05) was detected only in RBC, with there being lower values in the SUP, although this group also showed a tendency toward having an increased mean corpuscular hemoglobin level. There were no differences (p>0.05) in total protein and serum lysozyme concentrations or in WBCs between diets, except for lymphocytes, which presented lower values (p<0.05) in the SUP, suggesting immunomodulation by the polyunsaturated fatty acids present in the microalga. There was no difference (p>0.05) in the intestinal morphology between diets. Metagenomic data indicated greater richness (represented by the Chao index) and a higher abundance of the bacterial phylum Firmicutes in the gut microbiota of the tilapia fed with the SUP diet, demonstrating that the digestion and use of the components of the microalga could influence the microbial community. The results indicated that the microalga had modulatory effects on blood cells and the intestinal microbiota, without affecting the structure and integrity of the intestinal villi.

Structure and genetic variability of golden mussel (Limnoperna fortunei) populations from Brazilian reservoirs.

The golden mussel, Limnoperna fortunei a highly invasive species in Brazil, has generated productive, economical, and biological impacts. To evaluate genetic structure and variability of L. fortunei populations present in fish farms in the reservoirs of Canoas I (CANFF), Rosana (ROSFF), and Capivara (CAPFF) (Paranapanema River, Paraná, Brazil), eight microsatellite loci were amplified. Five of those eight loci resulted in 38 alleles. The observed heterozygosity (Ho) was lower than the expected heterozygosity (He) in all populations, with a deviation from the Hardy-Weinberg equilibrium (HWE). The average value for the inbreeding coefficient (Fis) was positive and significative for all populations. There was higher genetic variability within populations than among them. The fixation index (Fst) showed a small genetic variability among these populations. The occurrence of gene flow was identified in all populations, along with the lack of a recent bottleneck effect. The clustering analysis yielded K = 2, with genetic similarity between the three populations. The results demonstrate low genetic structure and suggest a founding population with greater genetic variability (ROSFF). Our data point to the possible dispersal of L. fortunei aided by anthropic factors in the upstream direction. It was concluded that the three populations presented a unique genetic pool for Paranapanema River, with occurrence of gene flow.

Transferability of heterologous microsatellite primers in Brycon gouldingi / Transferibilidade de primers microssatélites heterólogos em Brycon gouldingi

ABSTRACT: Brycon gouldingi is a species of neotropical fish of socioeconomic and environmental importance in the Tocantins-Araguaia Basin. Genetic studies on this species are still limited, making it difficult to evaluate the population structure and genetic diversity in natural and captive stocks. Here, we aimed to evaluate the transferability of heterologous microsatellite primers in B. gouldingi. A total of 30 primers for eight species were evaluated: Brycon hilarii, Brycon opalinus, Brycon cephalus, Brycon orbignyanus, Prochilodus lineatus, Prochilodus argenteus, Piaractus mesopotamicus, and Colossoma macropomum. The primers that showed the best amplification patterns were applied to 20 specimens of B. gouldingi, and their genetic parameters were assessed. Among the 30 primers, seven showed satisfactory transferability, six of which belonged to the genus Brycon: Bh13 (B. hilarii), BoM5, BoM13 (B. opalinus), Borg9, Borg13, and Borg59 (B. orbignyanus), and one belonged to P. argenteus (Par80). The primers for the other species tested showed non-specificity or monomorphism; and were therefore, excluded from the analyses. The number of alleles ranged between two (Borg13 and Borg59) and three (Bh13, BoM5, BoM13, Borg9 and Par80), with sizes varying between 103 bp (BoM5) and 430 bp (Borg9). Four primers showed evidence of null alleles (BoM13, Borg9, Borg13, and Par80), which could probably be attributed to the respective Hardy-Weinberg deviation. Thus, seven primers were validated for cross-amplification in B. gouldingi, which may be used in future studies involving this species.

RESUMO: Brycon gouldingi é uma espécie de peixe neotropical com importância socioeconômica e ambiental na Bacia do Tocantins-Araguaia. Estudos genéticos nessa espécie ainda são escassos, dificultando o conhecimento sobre a estrutura populacional e a diversidade genética nos estoques naturais e em cativeiro. O objetivo do presente estudo foi avaliar a transferibilidade de primers microssatélites heterólogos em B. gouldingi. Foram avaliados um total de 30 primers de oito espécies: Brycon hilarii, Brycon opalinus, Brycon cephalus, Brycon orbignyanus, Prochilodus lineatus, Prochilodus argenteus, Piaractus mesopotamicus e Colossoma macropomum. Os primers que demonstraram melhores padrões de amplificação foram aplicados em 20 espécimes de B. gouldingi para os cálculos dos parâmetros genéticos. Sete dos 30 primers apresentaram resultados satisfatórios de transferibilidade, sendo seis oriundos do gênero Brycon: Bh13 (B. hilarii), BoM5, BoM13 (B. opalinus), Borg9, Borg13 e Borg59 (B. orbignyanus), e um oriundo de P. argenteus (Par80). Os primer das outras espécies testados mostraram inespecificidade ou monomorfismo, sendo excluídos das análises. O número de alelos variou de dois (Borg13 e Borg59) a três (Bh13, BoM5, BoM13, Borg9 e Par80), com tamanhos entre 103 pb (BoM5) e 430 pb (Borg9). Quatro primers apresentaram evidências de alelos nulos (BoM13, Borg9, Borg13 e Par80), o que provavelmente inferiu sobre o desvio de Hardy-Weinberg nos mesmos. Concluindo, sete primers foram validados para a amplificação cruzada em B. gouldingi e poderão ser utilizados em futuros estudos com essa espécie.

Cross-amplification of heterologous microsatellite markers in Piracanjuba / Amplificação cruzada de marcadores microssatélites heterólogos em piracanjuba

ABSTRACT: Brycon orbignyanus, popularly known in Brazil as piracanjuba, is a fish with great economic value but whose natural population drastically decreased in number during the last years. In this context, genetic variability studies of natural stocks and in restocking programs are fundamental for the adoption of conservation measures. Current analysis verifies the cross-amplification of heterologous primers in B. orbignyanus. Fifty-two primers of the species Brycon opalinus, Brycon hilarii, Brycon insignis, Prochilodus sp., Piaractus mesopotamicus, Colossoma macropomum and Oreochromis niloticus were tested. Primers with the best reproducibility were applied to a sample of 20 individuals and the genetic parameters were calculated. Nine primers provided good results for cross-amplification with B. orbignyanus, involving (BoM5 and BoM13) of Brycon opalinus, (Bh5, Bh6, Bh8, Bh13 and Bh16) of Brycon hilarii, (Bc48-10) of Brycon insignis and (Par80) of Prochilodus argenteus. Primers of Piaractus mesopotamicus, Colossoma macropomum and Oreochromis niloticus failed to provide amplification or provided non-specificity. Results demonstrated the possibility of using primers of different species and genera of B. orbignyanus, facilitating genetic studies on the species.

RESUMO: A piracanjuba (Brycon orbignyanus) é um peixe de grande valor econômico que nos últimos anos tem apresentado uma redução drástica em suas populações naturais. Nesse contexto, estudos de variabilidade genética dos estoques naturais e nos programas de repovoamento são fundamentais para adoção de medidas conservacionistas. O objetivo do presente trabalho foi verificar a amplificação cruzada de primers heterologos em B. orbignyanus. Foram avaliados um total de 52 primers das espécies Brycon opalinus, Brycon hilarii, Brycon insignis, Prochilodus sp., Piaractus mesopotamicus, Colossoma macropomum e Oreochromis niloticus. Os primers com melhor reprodutibilidade foram aplicados a uma amostra de 20 indivíduos e os parâmetros genéticos foram calculados. Nove primers apresentaram resultados satisfatórios de amplificação cruzada com B. orbignyanus, sendo das espécies Brycon opalinus (BoM5 e BoM13), Brycon hilarii (Bh5, Bh6, Bh8, Bh13 e Bh16), Brycon insignis (Bc48-10) e Prochilodus argenteus (Par80). Os primers de Piaractus mesopotamicus, Colossoma macropomum e Oreochromis niloticus não apresentaram amplificação ou apresentaram inespecificidade. Os resultados revelaram a possibilidade da utilização de primers de diferentes espécies e gênero em B. orbignyanus, o que facilita a realização de estudos genéticos nessa espécie.