Abstract A total of 381 specimens of the tilapia Oreochromis mossambicus collected monthly from May 2017 to May 2018 in the Laguna de Los Patos, Cumaná, Venezuela, to evaluate reproductive parameters of this non-native species. Significant differences were found in relation to average height and weight between males and females, with the highest values in males. The sex ratio was 1:1.5 (males:females), which deviates significantly from the expected 1:1 ratio. The mean length of sexual maturity (Lm50) was 18.0 cm in females and 20.1 cm in males, reflecting that females mature at smaller sizes than males. The monthly variations of the gonadosomatic index (GSI) and the stages of sexual maturity show two reproductive peaks during the study, in October 2017 and April 2018, coinciding with the rainy and dry seasons in the region respectively. The condition factor (CF) showed significant differences between months, but not between sexes, with an average of 1.87 in females and 1.84 in males. The average absolute fecundity was 921 ± 604.6 eggs per fish, with a relative fecundity of 8.36 ± 3.09 eggs per gram of fish. Differences in oocyte size in mature females confirm that the species can spawn repeatedly over a period, which is considered an important factor for the establishment of tilapia in non-native environments. 38 201 Patos Cumaná Venezuela nonnative non native 11.5 115 1 1.5 5 1:1. malesfemales, malesfemales , (males:females) 11 1: Lm50 Lm (Lm50 180 18 0 18. 20 20. GSI (GSI study respectively CF (CF months sexes 187 87 1.8 184 84 92 6046 604 6 604. fish 836 8 36 8.3 309 3 09 3.0 period environments 11. 15 1. (males:females Lm5 (Lm5 2 9 60 83 8. 30 3. (Lm

Resumo Um total de 381 espécimes da tilápia Oreochromis mossambicus foram coletados mensalmente de maio de 2017 a maio de 2018, na Laguna de Los Patos, Cumaná, Venezuela, para avaliar parâmetros reprodutivos desta espécie não nativa. Foram encontradas diferenças significativas em relação às médias de altura e peso entre machos e fêmeas, sendo os maiores valores no sexo masculino. A razão sexual foi de 1:1,5 (machos:fêmeas), o que se desvia significativamente da proporção esperada de 1:1. O comprimento médio de maturação sexual (Lm50) foi de 18,0 cm nas fêmeas e 20,1 cm nos machos, refletindo que as fêmeas amadurecem em tamanhos menores que os machos. As variações mensais do índice gonadossomático (IGS) e dos estágios de maturidade sexual mostram dois picos reprodutivos durante o estudo, em outubro de 2017 e abril de 2018, coincidindo com as estações chuvosa e seca na região, respectivamente. O fator de condição (FC) apresentou diferenças significativas entre os meses, mas não entre os sexos, com média de 1,87 no sexo feminino e 1,84 no masculino. A fecundidade absoluta média foi de 921 ± 604,6 ovos por peixe, com fecundidade relativa de 8,36 ± 3,09 ovos por grama de peixe. Diferenças no tamanho dos ovócitos em fêmeas maduras confirmam que a espécie pode desovar repetidamente ao longo de um período, o que é considerado um fator importante para o estabelecimento de tilápias em ambientes não nativos. 38 201 2018 Patos Cumaná Venezuela nativa masculino 11,5 115 1 1,5 5 1:1, machosfêmeas, machosfêmeas , (machos:fêmeas) 11. 11 1. 1:1 Lm50 Lm (Lm50 180 18 0 18, 20 20, IGS (IGS estudo região respectivamente FC (FC meses sexos 187 87 1,8 184 84 92 6046 604 6 604, peixe 836 8 36 8,3 309 3 09 3,0 período nativos 11, 15 1, (machos:fêmeas 1: Lm5 (Lm5 2 9 60 83 8, 30 3, (Lm

Objetivo. El objetivo de este trabajo fue evaluar el efecto de la adición de proteínas del plasma seminal sobre el porcentaje de espermatozoides bovinos viables post-descongelación. Materiales y métodos. Los espermatozoides se congelaron usando dos medios (citrato-fructosa-yema y Bioxcell®) y la obtención de proteínas de plasma seminal de bajo peso molecular se realizó por medio de cromatografía líquida de baja presión. Las proteínas de interés eluyeron en las fracciones 21-25 y se sometieron a electroforésis en una y dos dimensiones. Los espermatozoides se incubaron a 37°C durante una hora, con 0.5, 1.0, 1.5 y 2.0 mg de la fracción 21-25. Se incluyeron dos tratamientos adicionales: uno con proteínas totales del plasma seminal y otro sin proteína. Resultados. La electroforésis bidimensional de las fracciones confirmó la presencia de siete puntos de proteína de bajo peso molecular (14-16 kDa y punto Isoeléctrico de 5.0 - 5.5). La adición de estas proteínas aumentó 20% (p<0.05), el porcentaje de espermatozoides viables post-descongelación en muestras congeladas en medio citrato-fructosa-yema (con dosis de 1 ó 1.5 mg de proteína/10(6) espermatozoides), y 25% (p<0.05) en muestras congeladas en medio Bioxcell® (con dosis de 0.5 mg de proteína/106 espermatozoides). Cryopreservation, heat shock proteins, seminal plasma, sperm capacitation, sperm Los resultados de esta investigación sugieren el posible uso de proteínas de bajo peso molecular del plasma seminal, para disminuir el efecto deletéreo de la criopreservación en los espermatozoides.

Objective. This study was performed to evaluate the effect of the addition of proteins on the post-thawing viability of spermatozoa. Materials and methods. Spermatozoa were frozen with two different media: Citrate-fructose and Bioxcell®. The isolation of seminal plasma proteins of low molecular weight was performed through low pressure liquid chromatography. It was determined that the proteins of interest eluted in fractions 21-25, and two dimensional electrophoresis was performed. Thawed sperm was incubated at 37°C for one hour with 0.5, 1, 1.5 and 2.0 mg of 21-25 fraction protein. Two additional treatments were included: one with seminal plasma total protein, and another one without protein. Results. Two dimensional electrophoresis of protein confirmed the presence of two bands of 14 and 16 kDa and seven spots with iso-electric points between 5.0 - 5.5 respectively. Incubation of the spermatozoa with the 21-25 fraction showed that sperm viability increases by 20% with doses of 1 and 1.5 mg of protein/106 spermatozoa in the citrate-fructose medium, and 25% with 0.5 mg of protein/106 spermatozoa in Bioxcell® medium. A positive effect in sperm viability was demonstrated although it depends on the doses of protein and the cryopreservation medium used. Conclusions. This investigation suggests that the use of seminal plasma proteins can be useful for reducing the harmful effect on sperm cryopreservation.