Hugo Pereira Godinho

Sperm quality and cryopreservation of Brazilian freshwater fish species: a review.

The Brazilian freshwater fish diversity is the richest in the world. Only 0.7% of all Brazilian species have had any aspect of their sperm biology addressed up to this date. The majority of the fish species described in this review migrate during the spawning season (a phenomenon known as piracema). Urbanization, pollution, hydroelectric dams and deforestation are some of the causes of stock depletion or even local extinction of some of these species. The knowledge concerning sperm quality and minimum sperm:egg ratio is important to maximize the use of males without reducing hatching rates. Furthermore, sperm cryopreservation and gene banking can guarantee the conservation of genetic diversity and development of adequate breeding programs of native fish species. In this review, we present and evaluate the existing information on Brazilian fish species that have been subject to sperm quality and cryopreservation studies. The following parameters were evaluated: volume of extractable sperm, sperm motility, sperm concentration, freezing media, freezing methods, and post-thaw sperm quality. Although the existing protocols yield relatively high post-thaw motility and fertilization rates, the use of cryopreserved sperm in routine hatchery production is still limited in Brazil.

Cryogenic preservation of spermatozoa from Prochilodus scrofa and Salminus maxillosus

Abstract This paper reports an initial trial to cryopreserve semen from two freshwater South American fishes, the curimbata ( Prochilodus scrofa ) and the dourado ( Salminus maxillosus ). Motility and duration of motility were observed in curimbata and dourado fresh sperm. Semen mixed with extender (0.8% NaCl) was frozen using vials (1 ml) with subsequent storage in liquid nitrogen. Samples were thawed in 1% NaHCO 3 or in 0.8% NaCl solutions. Post-thawing motility and duration of motility were verified. A simple extender consisting of 0.8% NaCl plus 10% DMSO was able to initiate motility in fresh spermatozoa. The percentage of motile cells and duration of motility were similar in both thawing solutions, but lower than in fresh sperm.

Cortical alveoli in oocytes of freshwater neotropical teleost fish

Abstract Depending on the species, the teleost cortical alveolus (CA) has from one to several layers of small to large cortical vesicles forming a continuous or discontinuous collar in the peripheral ooplasm. The histochemical composition of the CA, which also varies among species, is made of neutral glycoprotein, carboxylated glycocon‐jugate, neutral glycoprotein plus carboxylated glycoconjugate, sulfated glycoconjugate, neutral glycoprotein plus sialic acid‐rich glycoprotein. The CA was sudanophobic in all species analyzed. The morphology and contents of the CA seem to express common characters among many of the groups studies. Variations in the morphology and contents of the CA may be related to different mechanisms of polyspermy blockade.

Reproductive traits of the yellow-mandi catfish Pime/odus maculatus Lacepede (Osteichthyes, Siluriformes) in captive breeding

Pimelodus maculatus Lacepede, 1803 is an important fish of the Sao Francisco river basin, where it is economically significant in both professional and sports fisheries. The fish, maintained in captivity, was subjected to hypophysation with crude caip pituitary extract. Approximately 70% of the females treated spawned viable eggs. The eggs were opaque, demersal, yellow and free. Egg stripping was performed at 213 hour-degrees (duration = 8.3 h) after the second dose injection, at water temperature of 25-26oC. Hatching occurred at 394 hour-degrees (duration = 16.3 h) after egg fertilization, at water temperature of 24-25oC. Egg fertilization rate was 64.8%. The relationship between absolute fecundity (AF), initial fertility (IF) and final fertility (FF) and body weight are expressed, respectively, by AF = - 331 + 181717 Wt (r2 = 0.62), IF = - 16839+ 158123 Wt (r2 = 0.65), and FF = -9874 + 100365 Wt (r2 = 0.63).

Induced spawning of the pacu, Colossoma mitrei (Berg, 1895), by hypophysation with crude carp pituitary extract

Abstract Ovulation and spermiation of pacu, Colossoma mitrei (Berg 1895), were induced with crude carp pituitary extract. Each female was injected with two doses containing, respectively, 0.5 and 5.0 mg of dried pituitaries per kg of body weight, with an 18-h interval between doses. Each male received a single dose of the same extract containing 0.5 mg of dried pituitary per kg of body weight. The ‘dry’ method of fertilization was used. Water temperature during the experiments ranged from 22 to 24.5°C. Ovulation occurred at 305 ± 13 degree-hours. The ratio, in percentage, of ova: body weight was 8.2 ± 3.5. The number of oocytes per gram of ova varied from 1249 to 1695 with an average of 1531 ± 136. Oocyte diameter increased significantly from 1097 ± 14 μm prior to the first dose, to 1252 ± 14 μm at stripping. The degree-hours to hatching varied between 559 and 575, with an average of 565 ± 7. Hatching percentage varied from 77 to 92.

Morphofunctional changes of female germinal epithelium to support spermatozoa along the annual reproductive cycle in an inseminating catfish (Trachelyopterus galeatus, Auchenipteridae).

The reproductive system of some fish species presents elaborate mechanisms by which the females store spermatozoa inside their ovaries, keeping them viable for fertilization for an extended period of time. However, as intriguing as this sperm storage is, it is not yet understood how the sperm can remain viable in the ovary. Aiming to understand this phenomenon, the epithelium covering the ovarian lamellae, that is, the germinal epithelium, of the Cangati (Trachelyopterus galeatus), an inseminating catfish, was evaluated taking into account the different stages of the annual reproductive cycle. The germinal epithelium morphology changed during the annual reproductive cycle, presumably in preparation to receive the spermatozoa and keep them viable until fertilization. There was a progressive increase of the epithelium height. Also the number of intercellular junctions, desmosomes, and extended tight junctions, apparently increased forming chains that could be regarded as a barrier to isolate the sperm from the female immune system. Synthetic organelles were active releasing cytoplasmic granules and secretion in the epithelial enfolds in which the spermatozoa were deeply embedded. Concomitantly, oogonium nests were formed in the germinal epithelium during early folliculogenesis. J. Morphol. 275:65–75, 2014.

Fisheries, life-history and conservation status of the catfish pirá Conorhynchos conirostris (Ostariophysi: Siluriformes) in Brazil

Pirá, Conorhynchos conirostris (Valenciennes, 1840), a large migratory catfish endemic to the São Francisco River (SFR), is listed as threatened in the red lists of both Brazil and the state of Minas Gerais. Although fishing for pirá has been prohibited, it is still an important fishery resource, particularly in the middle SFR. We used historical and current occurrence and abundance data regarding pirá to determine if it meets the IUCN criteria of a threatened species. Pirá occurs in the main course of the SFR as well as in its major tributaries. Unlike the most well-known migratory fishes of the SFR, pirá does not use floodplain lakes as nurseries. In the first half of the 20th century, pirá occurred from the upper to the lower SFR. Currently, it is most abundant in the middle SFR, and is rare in the upper SFR and even rarer in the sub-middle SFR. Pirá has not been captured in the lower SFR since around the mid-1980’s. Despite the reduction in its geographic distribution, we did not find evidence to justify considering pirá as threatened. Thus, we recommend that it be removed from the red lists of Brazil and the state of Minas Gerais.