RESUMEN.Hasta el momento los estudios sobre reproducción en Macrobrachium acanthurus están poco avanzados siendo importantes si se prevé la posibilidad de su cultivo. El objetivo de este trabajo fue identificar el voltaje más adecuado para la extracción de los espermatóforos y la menor talla con que estos langostinos los producen, como paso previo a desarrollar técnicas de fecundación in vitro. Se utilizaron voltajes de 4,5 y 6,0 voltios, realizándose el conteo de los espermatozoides en base a la supervivencia espermática en frotis coloreados con eosina-nigrosina. En el estudio de las tallas, los langostinos fueron separados en intervalos de clases y analizados en cuanto a la producción de espermatóforos y la supervivencia espermática. El mejor voltaje para la extracción del material seminal debido a menores mortalidades fue 6,0 voltios, a partir de 5 g de peso corporal y 18 mm de longitud de caparazón, cuando los langostinos pueden ser utilizados para la extracción de espermatóforos. Palabras clave: Macrobrachium acanthurus, Caridea, espermatozoides, reproducción, supervivencia espermática. Determination of adequate voltage and animal size for the extraction of spermatophores in the freshwater prawn Macrobrachium acanthurusABSTRACT. So far Macrobrachium acanthurus reproduction studies are poorly advanced being important if there is the possibility of cultivation. The aim of this study was to identify the most suitable voltage for the extraction of spermatophores and the smaller size at which these prawns produce them, as a prior step to develop in vitro fertilization techniques. Voltages of 4.5 and 6.0 were used, performing sperm count based on survival of sperm smears, colored with eosin-nigrosine. In the study of size, prawns were separated into class intervals and analyzed for production of spermatophore and sperm survival. The best voltage for the extraction of seminal material due to lower mortality was 6.0 volts and from 5 g of body weight, and 18 mm of length prawns could be used for the extraction of spermatophores.
The freshwater prawn M. amazonicum is widely consumed by the traditional communities of the Amazon basin. This species is captured by traps throughout the year and particularly during the Amazon dry season, when animals are concentrated in floodplain lakes. The aim of this paper was to know the populational biology of M. amazonicum in the Macurany and Catispera lakes, both located in the city of Parintins, Amazonas, Brazil. Samples were collected monthly from September 2009 to April 2010, using regional fishing gear. Males, females and total fertility were significantly higher in Catispera lake. The largest ovigerous female was recorded for the Catispera lake (56.2 mm) and low to the Macurany lake (18.3 mm). Sexually undifferentiated individuals were captured throughout the collection period in both lakes. It was observed a higher proportion of females than males (1:2.6) in Macurany lake. The reproductive peak was in the full-flood period (December to April). It may be related to the greatest flow of river and overflowing the banks of lakes, which contribute to larvae dispersion.
RESUMOA primeira estapa deste trabalho testou a toxicidade de quatro crioprotetores em espermatozoides de Macrobrachium acanthurus durante 10 e 20 min nas concentrações de 10 e 20%. A segunda etapa foi realizar a criopreservação aplicando o crioprotetor com menor grau de toxicidade, testanto dois mecanismos de congelamento, um automatizado (protocolos A e B) e outro convencional (protocolos C e D), durante 24 horas. O protocolo A apresentou velocidade de resfriamento de 0,5°C min -1 até alcançar -32°C, partindo de uma temperatura de -6°C e idem o protocolo B, com a diferença de partir de uma temperatura ambiente; os protocolos C e D apresentaram uma velocidade de resfriamento de 2 e 10°C min -1 , respectivamente, sendo as palhetas transferidas ao nitrogênio líquido. A terceira etapa foi verificar o tempo de vida do espermatozoide quando refrigerado a 5°C. A viabilidade espermática foi avaliada por meio do esfregaço de sêmen com eosina-nigrosina. Os crioprotetores que se apresentaram menos tóxicos foram o glicerol 10 e 20% e metanol 10%, num tempo de equilíbrio de 10 minutos. A melhor velocidade de congelamento foi a de 2°C min -1 para glicerol 10%, com 21,8% de sobrevivência espermática, sendo a refrigeração até três dias recomendada, com uma sobrevivência de 35,3%.Palavras-chave: caridea; criopreservação; crioprotetores; glicerol; metanol; pitú ABSTRACTIn the first part of this study, toxicity tests were performed on the sperm of Macrobrachium acanthurus using four cryoprotectants for periods of 10 and 20 min at concentrations of 10 and 20%. In the second part, cryopreservation was performed by applying the least toxic cryoprotectant, and two freezing methods were tested over 24 hours: automated (protocols A and B) and conventional (protocols C and D). Protocol A exhibited a cooling rate of 0.5°C min -1 from -6°C to -32°C; protocol B was similar to A except for the starting temperature, which was room temperature; whereas protocols C and D exhibited a cooling rate of 2 and 10°C min -1 , respectively. The third part of the study was conducted to assess the lifespan of the sperm when stored at 5°C, in which sperm viability was evaluated by a semen smear with eosin-nigrosin. The least toxic cryoprotectants were 10 and 20% glycerol, and 10% methanol, and the equilibrium time was 10 minutes. The optimal cooling rate was 2°C min -1 for 10% glycerol, which had a sperm survival rate of 21.8%. Cold storage for up to 3 days is recommended, presenting a sperm survival rate of 35.3%.
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