Viviane de Oliveira Felizardo

Dose inseminante utilizada na fertilização artificial de ovócito de piracanjuba (Brycon orbignyanus)

Piracanjuba (Brycon orbignyanus Valenciennes, 1849) is an migratory fish listed as an endangered species. The aim of this study was to determine the insemination dose for in vitro fertilization of piracanjuba oocytes. The experiments were arranged in a randomized block design with four treatments and three replications. Three piracanjuba couples selected from the breeding tanks at the Itutinga Environmental Station (IES-CEMIG), Minas Gerais State, Brazil, in the spawning period of 2006-2007, were applied crude extract of carp pituitary hormone for the production of gametes. Four different treatments were used for fertilization of 0.1 gram of oocytes: 10 µL, 20 µL, 30 µL and 40 µL of sperm. The samples were activated with 5 mL of water from the tank and then taken to a hatchery with constant water flow and temperature at 28 oC. After 8 and 16 hours, the rates of fertilization (viable eggs) and hatching eggs were analyzed, respectively. The results were compared by Tukey test at 5% probability level. Tested sperm/oocyte ratios did not alter the rates of fertilization and hatching (P>0.05). The sperm/oocyte ratio ranging from 10.4 x105 to 41.6 x105 was efficient to achieve good fertility rates.

Effect of photoperiod stress assessment and locomotor activity of female lambari (Astyanax bimaculatu)

Some studies and scientific investments have been done in aquaculture aiming to minimize the stress of the fish due to different factors, as management, nutritional status, water quality, temperature, photoperiod, and salinity. This study aimed to verify the effect of photoperiod on locomotor activity and plasma levels of cortisol and glucose in female Lambari. One hundred and twenty female Lambari adult were maintained in aquaria of 20 liters each in a completely randomized design with three treatments (T1 = 0Light: 24Dark, T2 = 12L: 12D, T3 = 24L: 0D) and four replications. The daily locomotor activity was registered during 15 days using an infrared photocell. After 40 days of experiment and previous fasting for 24 hours, fish were euthanized by a lethal dose of benzocaine. Female Lambari featured a diurnal rhythm of locomotor activity. Lambari subjected to 12:12 and LD photoperiod presented higher cortisol (12L:12E: 190.00 ± 37.73 ng/mL e 24L:0E: 148.850 ± 32.77 ng/mL) and locomotor activity levels and also lower survival rates (30.0 ± 7.07%) when compared to the LD photoperiod (cortisol: 85.570 ± 7.99 ng/mL, survival rates: 72.5 ± 4.330%). The glucose concentration (32.167 ± 22.73 mg/dL) and the growth (7.050 ±0.59cm) of fish subjected to LD photoperiod was significantly lower than in the other treatments. We conclude that light plays an important role in the growth, behavior and welfare of female Lambari. Besides, our data highlighted that fish submitted to a long light period present a more stressed and more aggressive status when compared to fish submitted to a continuous darkness.

Vitamin E and reduced glutathione in Prochilodus lineatus (curimba) semen cryopreservation (Characiformes: Prochilodontidae)

This study investigated the addition of antioxidants vitamin E and reduced glutathione on curimba (Prochilodus lineatus) semen cryopreservation and compared sodium bicarbonate solution and distilled water as activators. The experiment was conducted at the environmental station of CEMIG, in Itutinga-MG, Brazil, between December/2009 and January/2010. Semen samples (n = 7) with semen motility above 80% were diluted in cryoprotectant solutions composed of 10% methanol, 15% lactose and containing different concentrations of antioxidants: 50 (VE50), 100 (VE100) and 250 (VE250) µM of vitamin E, and 0.5 (RG0.5), 1.0 (RG1.0) and 1.5 (RG1.5) mM of reduced glutathione. A solution without antioxidants was used as a control. The semen was diluted at a ratio of 1:4 (100 iL semen:400 ∝L cryoprotectant solution). The toxicity of the solutions was evaluated by investigating semen motility after 10 min in the solution. The rest of the diluted semen was placed into 0.5 mL straws maintained in nitrogen vapour for 24 hours and packed into a nitrogen liquid cylinder for four days. The samples were thawed in a water bath at 60°C for 8 s and the rate (%) and duration (s) of semen activation with distilled water or sodium bicarbonate was evaluated. In the toxicity test, we found that vitamin E and reduced glutathione were not toxic to curimba semen at any of the tested concentrations (P>0.05). The duration of motility was longer (P 0.05). Thus, the antioxidants vitamin E and reduced glutathione did not improve the quality of cryopreserved curimba semen, but they did not cause toxic effects to the semen in natura and they did not decrease its quality during cryopreservation.

Osmolaridade e taxa de diluição na ativação do sêmen criopreservado de prochilodus lineatus

Objetivou-se avaliar a influencia de ativadores com diferentes osmolaridades e taxa de diluicao na ativacao de semen criopreservado de curimba (Prochilodus lineatus). Foram utilizados quatro reprodutores machos capturados na Estacao de Piscicultura da CEMIG, Itutinga, MG. As amostras de semen foram diluidas em duas solucoes (DMSO + lactose e metanol + lactose) na proporcao de 1:4 e congeladas. Foram avaliadas as taxas (%) e duracao (s) da motilidade espermatica dos tratamentos. Na ativacao foram utilizados ativadores contendo as respectivas osmolarida- des: 30, 99, 183 e 293 mOsm nas taxas de diluicao de 1:2, 1:4, 1:6, 1:8 semen: ativador. A taxa de diluicao 1:2 e 1:8 foram estatisticamente significa- tivas para duracao da motilidade para o semen criopreservado com DMSO. Para a diluicao 1:2, o semen ativado com o ativador contendo 30 mOsm, apresentou duracao de motilidade maior em relacao ao semen ativado com ativadores com 183 e 293 mOsm. No entanto, para a utilizacao do ativador com 30 mOsm, se obteve maior duracao da motilidade na diluicao de 1:2 em relacao a diluicao de 1:4. Na taxa de diluicao 1:6, quando o semen foi ativado com o ativador de 30 mOsm, a taxa de motilidade foi superior a apresentada pelo semen que foi ativado com 293 mOsm. Na taxa de diluicao de 1:8, o uso de ativador contendo 99 mOsm apresentou maior duracao de motilidade em relacao ao uso do ativador com 293 mOsm. Ativadores contendo altas osmolaridades podem proporcio- nar menores taxas e duracao da motilidade em semen de curimba (Prochilodus lineatus) crio- preservado com os crioprotetores metanol ou DMSO.

Reproductive dynamics of Leporinus obtusidens captured downstream from an important hydropower Station in Brazil

This study evaluated the reproductive dynamics and gonadal morphology of piaparas (Leporinus obtusidens) captured downstream from the Funil Hydroelectric Power Station. The 107 piaparas evaluated were captured monthly from Sep 2006 to Aug 2007. The data were stratified among the seasons to evaluate gonad maturation and the reproductive period was determined by assessing the gonadosomatic index, hepatosomatic index, abdominal fat index (AFI), weight:length ratio, condition factor and sexual proportion. The reproductive period lasted from winter to summer (Jul-Mar) in females and from spring to autumn (Sept-Jun) in males. AFI was high during and after the reproductive period in females and only during the reproductive period in males. The highest HIS values for males and females were obtained in spring and summer (Sept-Mar). The females observed did not spawn and showed follicular atresia. These characteristics suggest that L. obtusidens does not use the study area as a reproductive site and probably migrates for this purpose.

Anormalidades espermáticas de Piaractus mesopotamicus após descongelamento utilizando diferentes metodologias

This study aimed to evaluate the influence of cryoprotectants, thawing times and temperatures on pacu (Piaractus mesopotamicus) sperm abnormalities. Semen samples from four pacu were collected and diluted in 2 solutions, cryoprotectant dimethylsulfoxide (DMSO) 10% and methanol 10%. After thawing, semen was collected for morphological analysis, evaluating primary and secondary abnormalities. There was no interaction (P>0.05) of secondary abnormalities, abnormalities in total and normal sperm in the different treatments. The primary abnormalities showed interaction between temperature and thawing time, where the higher temperature was associated with the shortest time (60°C for 8s) or the lowest temperature associated with longer thawing (40°C for 12s) provided under (P<0.05) percentages of spermatozoa with primary abnormalities. In the process of semen cryopreservation of P. mesopotamicus using the cryoprotectants DMSO and methanol, it is recommended that thawing be performed at 40° C for 12 seconds or 60°C for 8 seconds.

Determinação do sexo em catfish de canal ( Ictalurus punctatus) utilizando endoscopia

A identificacao precoce do sexo em peixes e um procedimento importante para o desenvolvimento de estrategias que facilitem o manejo no plantel de reprodutores. A endoscopia pode ser utilizada para essa identificacao, embora em peixes seu uso ainda seja restrito. Diante disso, o objetivo deste trabalho foi validar o uso do endoscopio rigido via poro urogenital para determinacao do sexo do catfish de canal (Ictalurus punctatus). O equipamento utilizado foi um endoscopio Multipurpose Rigid™ 30o com 2,7 mm de diâmetro e 18 cm de comprimento. Foram examinados 60 peixes com peso variando entre 86 e 1.032 gramas nos quais foi introduzido o endoscopio via poro genital e, logo em seguida, eutanaziados para confirmacao do sexo. Amostras de tecido gonadal foram coletadas para avaliacao histologica do estadio de maturacao e confirmacao do sexo. Os resultados mostraram que dos 60 peixes examinados, 57 tiveram confirmacao positiva do sexo via endoscopia, o que corresponde a 95% da amostra. A utilizacao da endoscopia para determinacao do sexo em I. punctatus via poro genital e viavel.

Swimbladder abnormalities in piapara (Leporinus obtusidens) captured downstream of the Funil Dam

Os danos que as usinas hidreletricas causam na fauna aquatica tem sido relatados, mas novos estudos focando as especies nativas, especialmente os peixes de grande porte sao necessarios. O presente estudo descreve as anomalias de bexiga natatoria em piapara Leporinus obtusidens, uma especie de peixe migratorio, coletados a jusante da barragem da estacao Hidreletrica do Funil, Minas Gerais, Brasil. Os 117 exemplares coletados foram dissecados para avaliacao da bexiga natatoria na cavidade celomatica. As anormalidades detectadas em 14 dos peixes capturados (12%) foram ruptura do tecido com exteriorizacao da bexiga natatoria (N = 12) e formacao de projecoes da bexiga (N = 2). Os exemplares que apresentavam anormalidades de bexiga, possuiam peso superior a 1300 g em ambos os sexos. Este tipo de anomalia pode ser causado por processo infeccioso da bexiga, no entanto, nao foram detectados processos inflamatorios nesses peixes. O quadro de anomalias em bexiga natatoria em piapara sugere que os individuos foram submetidos a uma brusca despressurizacao, possivelmente relacionada a passagem pelas turbinas. Outros estudos comparativos sao necessarios para corroborar esta hipotese.

Ultrastructural and Morphometric Analysis of Gametes in Neotropical Teleost Fishes

This study was designed to identify and measure the gametes of neotropical fish using ultrastructural analysis. Number, shape and size of micropyle and ultrastructure of egg membrane and of the micropyle canal; the number and length of the longest and shortest ridge in the micropyle region beyond the structures of the sperm cell have been used as taxonomic tool in ichthyology . Gametes of six breeding pairs of Piaractus mesopotamicus, Brycon orbignyanus, Salminus brasiliensis and Prochilodus lineatus were collected, fixed and subjected to scanning electron microscopy for the observation and measurement of the structures. The results showed many similarities between the gametes of the studied species. An array of grooves and folds was observed in the micropyle in all species but not in the Prochilodus lineatus oocytes. The micropyle was funnel-shaped in all species. The oocytes showed a great variation in the diameters of major and minor micropyle ostium, evidencing different reproductive strategies. The sperm cells showed simple structures with ovoide heads, a cylindrical midpiece with a single flagellum and no acrosome. This study may contribute to a better understanding of fish reproductive biology, conservation genetics and breeding studies.

Influential Factors of Quality of Fish Gametes for Use of In Vitro Fertilization

Aquaculture is the fastest growing livestock activity in Brazil, producing important sources of protein for human consumption. Most Brazilian fish farms that work with native species perform in vitro reproduction, given that these migrating species cannot release gametes without hormonal induction. To succeed with in vitro reproduction, the evaluation of reproductive parameters of both genders is necessary. The objective of this review is to describe the main reproductive parameters of fish, which must be evaluated for in vitro reproduction.