Ultrastructure aspects of Brycon gouldingi (Teleostei, Characidae) related to swimming ability and feeding during larval development.

The larval ultrastructure of Brycon gouldingi related to swimming and feeding from hatching to total yolk absorption is described from scanning electron micrographs. Newly hatched larvae (time zero) had no mouth opening, undefined optic vesicles, an olfactory plate visible as a shallow depression, rudimentary gill arches, neural groove, embryonic fin and a primary neuromast in the dorsal region of the head. At the time of yolk absorption, 55 h post hatching, the larvae presented an optic vesicle comprising an optic cup and crystalline lens; a mouth with tongue, tapered teeth and taste buds; a ciliated olfactory cavity; branched gill arches; filled neural groove signalling central nervous system development; caudal, pectoral, dorsal and anal fins; and neuromasts distributed throughout the head and body. These characters are related to prey capture and swimming ability, key aspects of survival during the larval stage. The results of this study provide important information for exploitation and aquaculture of B. gouldingi.

Spermatozoon ultrastructure and semen parameters of Brycon vermelha (Characiformes, Characidae).

This study analyzed semen parameters and the ultrastructure of spermatozoa of Brycon vermelha. The semen was white and viscous, with a mean volume of 5.0±2.6 mL/kg body weight and mean spermatozoon concentration of 4.3±0.8×10(10) spermatozoa/mL. The estimated motility rate was 90%, with 50% of spermatozoa motile at 35.0±0.1 s and 100% immotile by 46.5±0.1 s. The spermatozoon of B. vermelha had a distinct head, midpiece, and flagellum. The ovoid head measured 1.9±0.2 µm by 1.3±0.1 µm, with its volume almost completely occupied by the nucleus, and was enveloped by an irregular nuclear membrane, with no acrosome vesicle. The nuclear fossa held the centriole complex and the initial segment of flagellum. The midpiece was symmetrical and measured 1.3±0.3µm. Mitochondria were scarce and restricted to the anterior region, while vesicles were absent. The posterior region of the midpiece was characterized by the absence of mitochondria and the presence of the cytoplasmic sheath. The flagellum, enclosed by the flagellar membrane, measured 29.6±3.4 µm, and possessed an axial filament containing a 9+2 microtubule pattern. The spermatozoa of B. vermelha appeared similar in structure to those of fish that breed through external fertilization, thus classifying them as uniflagellate anacrosomal aquasperm, or Type 1 aquasperm.

Morphological and morphometric aspects of early life stages of piabanha Brycon gouldingi (Characidae).

Adult specimens of piabanha Brycon gouldingi were collected from Rio das Mortes (Mato Grosso, Brazil), adapted to captivity and induced to spawn at Buriti Fisheries (Nova Mutum, MT, Brazil). The early developmental stages of B. gouldingi were then characterized. Samples were collected at pre-determined times from oocyte extrusion to total yolk absorption. Oocyte diameter, total larval length (LT ) and yolk-sac volume were measured. The mean ± s.d. duration of embryo developmental of B. gouldingi was 13·90 ± 0·06 h at 26·40 ± 1·13° C. The mean ± s.d. oocyte diameter was 1·13 ± 0·06 mm with 54% of oocytes ranging from 1·11 to 1·20 mm. Seven stages characterized the early developmental phase of this species: zygote, cleavage, morula, blastula, gastrula, histogenesis-organogenesis and hatching, with unique features related to each stage. At hatching, the larvae measured 3·40 ± 0·07 mm, presented an elongated shape with yolk-sac volume of 0·46 ± 0·08 µl, non-pigmented eyes and exhibited swimming ability. When the yolk was completely absorbed at 55 h post-hatch, mean ± larval LT was 6·68 ± 0·65 mm, the eyes were highly pigmented and the teeth were visible. These are the first reported findings on the initial developmental stages of B. gouldingi and could be used to improve captive breeding management and conservation practices.

Morfologia e quantificação da microbiota intestinal do curimbatá (Prochilodus lineatus) e do cascudo cinza (Pterygoplichthys anisitsi) cultivados em cativeiro / Morphology and quantification of intestinal microbiota of curimbatá (Prochilodus lineatus) and the gray armored catfish (Pterygoplichthys anisitsi) reared in captivity

Todos os animais vivem em íntima associação com micro-organismos que desempenham importantes funções em seu desenvolvimento normal. Nos vertebrados, a mais populosa e complexa comunidade de micro-organismos reside no trato intestinal. O intuito do estudo foi quantificar, classificar e verificar morfologicamente a população microbiana intestinal de duas importantes espécies de peixes de água doce, o curimbatá (Prochilodus lineatus) e o cascudo cinza (Pterygoplichthys anisitsi). As amostras foram coletadas por meio de raspagens da mucosa intestinal, diluídas seriadamente até 10-4, semeadas em placas contendo ágar soja tripticaseína (TSA) e ágar chocolate (AC) para contagem de bactérias totais e identificação morfológica por Gram, em aerobiose e em anaerobiose facultativa, respectivamente. As contagens de bactérias totais mostraram resultados que variaram entre 10³ e 10(4)ufc.mL-1. Os tipos morfológicos encontrados foram cocos, leveduras e bastonetes Gram negativos e positivos. Estudos adicionais sobre os padrões de colonização microbiana e a morfologia dos micro-organismos aderidos à mucosa intestinal foram possíveis com o uso da microscopia eletrônica de varredura (MEV), sendo encontradas formas variadas de micro-organismos, tais como leveduras, formas cocoides e bacilares flageladas e não flageladas. A microbiota intestinal do curimbatá e a do cascudo cinza provaram ser bastante diversas e populosas, com o predomínio de micro-organismos Gram negativos.

All animals exist in intimate associations with microorganisms that play important roles in the hosts' normal development. In vertebrates, the most populous and complex community of microbes resides in the digestive tract.The aim of this research was to morphologically quantify, classify and verify the composition of intestinal microbiota of two species of freshwater fish, the Prochilodus lineatus and the Pterygoplichthys anisitsi. The samples were collected by scrapings of intestinal mucosa, serially diluted to 10-4, plated on tryptic soy agar (TSA) and chocolate agar (CA) for total bacterial counting and morphological identification by Gram, in aerobiosis and facultative anaerobiosis conditions, respectively. In the total bacterial counting results ranged between 10³ to 10(4) cfu.mL-1. The morphological types found were cocci, yeasts and Gram negative and positive rods. Additional studies about patterns of microbial colonization and the morphology of the adhered microorganisms to the intestinal mucosa were possible using the scanning electron microscopy (SEM) and several forms of microorganisms, such as yeasts, cocci and bacillary shapes flagellated and non-flagellated were found. The intestinal microbiota of P. lineatus and P. anisitsi was diverse and populous, with a predominance of Gram negative microorganisms.

Sexagem histológica e desempenho de Oreochromis niloticus testando diâmetros de ração de acordo com o aparato bucal / Histological gender diagnosis and performance of Oreochromis niloticus testing diameters of crumble diet according to oral apparatus

Estudou-se o tamanho da boca de larvas de tilápia-do-nilo e testou-se o efeito de diferentes granulometrias da ração sobre o ganho de peso, comprimento e sobrevivência das larvas aos 30 e 60 dias de arraçoamento. Avaliou-se também o método de sexagem por meio de microscopia de luz aos 35 dias de idade. A medida da boca das larvas apresentou valores médios de 918,2±152,9μm aos cinco dias de idade. De acordo com esse dado, testaram-se três granulometrias: 0,25, 0,35 e 0,50mm. Aos 30 e aos 60 dias de arraçoamento, 10 por cento das larvas foram medidas, pesadas e contadas para cálculo da taxa de sobrevivência. O tamanho dos grânulos testados não afetou o desempenho das larvas de tilápia nilótica com alimentação iniciada aos cinco dias pós-eclosão. Quanto à sexagem histológica aos 35 dias de idade, as gônadas apresentaram-se, em sua maioria, indiferenciadas. Recomenda-se que essa análise deva ser realizada de acordo com o tamanho dos animais e não com a idade.

The mouth size of Nile tilapia larvae and the effect of different diameters of crumble fish food over weight gain, total length, and survival of larvae after 30 and 60 days of feeding were studied. The method of gender diagnosis based on light microscopy at 35 days of age was also evaluated. The larval mouth measurement presented average values of 918.2±152.9μm at five days of age. Based on this information, three granule sizes were tested: 0.25, 0.35, and 0.50mm. At 30 and 60 days of feeding, 10 percent of larvae were measured, weighed, and counted to calculate the survival rate. It was verified that the crumble size did not affect the performance of Nile tilapia larvae when feeding was initiated five days after hatching. In relation to the histological gender diagnosis at 35 days of age, most of gonads were undifferentiated. Therefore, it is recommended that this analysis should be carried out according to the size of animals instead of their age.