Sensibilidade dos espermatozoides de dourado (Salminus brasiliensis) a diferentes soluções crioprotetoras / Sensitivity of dourado (Salminus brasiliensis) spermatozoa to different cryoprotectant solutions

Em três experimentos, avaliou-se a sensibilidade dos espermatozoides de dourado (Salminus brasiliensis) a diferentes soluções crioprotetoras. No experimento 1, o sêmen foi diluído, 1:10, em 12 soluções (quatro diluidores x três crioprotetores - dimetilsulfóxido (DMSO), metilglicol ou glicerol). Metade de cada amostra foi resfriada por uma hora e a outra, criopreservada. A motilidade espermática foi avaliada imediatamente após a diluição e após o resfriamento em todas as amostras e, após o descongelamento, apenas nas amostras criopreservadas em DMSO. No experimento 2, o sêmen foi diluído, 1:5, em cinco soluções contendo DMSO e resfriado, criopreservado e avaliado como no experimento 1. No experimento 3, o sêmen foi diluído, 1:5, em quatro soluções contendo DMSO e criopreservado e avaliado quanto à motilidade e à fertilidade. Quando o sêmen foi diluído 1:10, observou-se motilidade acima de 58 por cento em todas as amostras resfriadas em DMSO e em NaCl-tris-metilglicol. Baixa motilidade foi observada nas amostras resfriadas nas outras combinações com metilglicol (5-32 por cento) ou glicerol (0-8 por cento) e naquelas criopreservadas (16-20 por cento). Todas as amostras diluídas 1:5 apresentaram motilidade de 65-72 por cento após o resfriamento e de 45-66 por cento após o descongelamento (experimentos 2 e 3). As taxas de eclosão produzidas com sêmen criopreservado, entretanto, foram baixas (17-23 por cento) em relação ao sêmen fresco (60 por cento).

The sensitivity of dourado (Salminus brasiliensis) spermatozoa to different cryoprotectant solutions was evaluated in three experiments. In experiment 1, semen was diluted, 1:10, in 12 solutions (four extenders x three cryoprotectants - dimethylsulphoxide (DMSO), methyglycol, or glycerol). Half of each sample was refrigerated for one hour while the other half was cryopreserved. Sperm motility was immediately assessed after dilution and after refrigeration in all samples, and after thawing in those cryopreserved in DMSO. In experiment 2, semen was diluted, 1:5, in five solutions containing DMSO, refrigerated, cryopreserved, and analyzed as in experiment 1. In experiment 3, semen was diluted, 1:5, in five solutions containing DMSO, cryopreserved and evaluated for motility and fertility. When semen was diluted 1:10, motility higher than 58 percent was observed in all samples refrigerated in DMSO and in NaCl-tris-methylglycol. Low motility was observed in samples refrigerated in the other combinations of methylglycol (5-32 percent) or glycerol (0-8 percent) and in those cryopreserved (16-20 percent). All samples diluted 1:5 yielded motility of 65-72 percent after refrigeration, and 45-66 percent after thawing (experiments 2 and 3). The hatching rates produced with cryopreserved semen, however, were lower (17-23 percent) compared to fresh semen (60 percent).

Genetic divergence between Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum (Siluriformes: Pimelodidae) in the Paraná River Basin / Divergência genética entre Pseudoplatystoma corruscans e Pseudoplatystoma reticulatum (Pisces; Siluriformes) da Bacia do Rio Paraná

Pseudoplatystoma corruscans (Spix and Agassiz, 1829) and Pseudoplatystoma reticulatum (Eingenmann and Eigenmann, 1889) are large migratory catfishes of high biological importance and great commercial value in South America. Because fertile crossbreeds can be artificially produced in hatcheries, a high genetic proximity between these two Pimelodidae species is conceivable. Possible escape of crossbred specimens from pisciculture stations is a serious environmental concern. Despite their importance, knowledge of P. corruscans and P. reticulatum biology, ecology, population diversity and genetics is limited. In the present work, the genetic divergence between P. corruscans and P. reticulatum populations from the Paraná River Basin was analyzed on the basis of polymorphisms in ISSR fragments and in the hypervariable sequence of the mitochondrial DNA (mtDNA) control region. Estimates of intraspecific haplotype (h > 0.5) and nucleotide diversities (π < 0.01) indicate that P. corruscans and P. reticulatum have survived a historical population decline, followed by a demographic expansion. The interspecific polymorphisms within the mtDNA control region and ISSR fragments were suitable as diagnostic molecular markers and could be used to discriminate the two species. A unique Pseudoplatystoma specimen, captured in the Upper Paraná River Floodplain, was identified by these DNA diagnostic markers as a hybrid P. reticulatum x P. corruscans, which possibly escaped from pisciculture. The integrity of the natural population of P. corruscans in the Upper Paraná River is at risk of genetic introgression or homogenization due to the presence of hybrids and the transposition of P. reticulatum upstream through the Canal da Piracema at Itaipu Dam. Data presented herein improve the understanding of the genetic relatedness between P. corruscans and P. reticulatum and represent potential tools for future programs of conservation and surveillance of genetic ...

Pseudoplatystoma corruscans Spix e Agassiz, 1829 e Pseudoplatystoma reticulatum Eigenmann e Eigenmann, 1889 são peixes migratórios de grande porte, com alta importância biológica e elevado valor comercial na América do Sul. Híbridos férteis são obtidos em cativeiro e, portanto, é esperada alta proximidade genética entre essas duas espécies de Pimelodidae. Escapes de espécimes híbridos a partir de estações de piscicultura representam um sério problema ambiental. Apesar da sua importância, conhecimentos sobre a biologia, ecologia, diversidade de populações e genética de P. corruscans e P. reticulatum são escassos. No presente trabalho, foi avaliada a divergência genética entre P. corruscans e P. reticulatum da Bacia do Rio Paraná, com base em fragmentos ISSR e na seqüência D-loop do DNA mitocondrial (mtDNA). As estimativas das diversidades intra-específicas haplotípica (h > 0,5) e nucleotídica (π < 0,01) evidenciaram que P. corruscans e P. reticulatum sobreviveram a um declínio populacional histórico, seguido de expansão demográfica. Os polimorfismos interespecíficos no mtDNA e nos fragmentos ISSR foram eficientes para diagnósticos e discriminaram as duas espécies. Um espécime de Pseudoplatystoma capturado na planície de inundação do Alto Rio Paraná foi identificado com esses marcadores moleculares como híbrido P. reticulatum x P. corruscans, que possivelmente escapou de psicicultura. A integridade da população de P. corruscans no Alto Rio Paraná está ameaçada, por introgressão ou homogeneização genética, pela presença de híbridos e pela transposição para montante de P. reticulatum através do Canal da Piracema em Itaipu. Os dados apresentados constituem um avanço na compreensão do parentesco entre P. corruscans e P. reticulatum e representam ferramentas em potencial para programas de conservação biológica, incluindo o monitoramento de introgressão e de integridade genética das populações.

Sucesso do resfriamento e congelamento de sêmen de pirapitinga Brycon nattereri / Sucess of cooling and freezing of pirapitinga (Brycon nattereri) semen

Avaliaram-se protocolos de resfriamento e de criopreservação do sêmen de pirapitinga (Brycon nattereri) utilizando-se sêmen diluído em NaCl 154mM, NaCl 200mM, Saad e BTS® e resfriado por sete dias. Cinco diluidores (glicose 277mM, NaCl 154mM, NaCl 200mM, Saad e BTS®) foram combinados com dois crioprotetores (DMSO - dimetilsulfóxido e metilglicol) e usados como meio de congelamento. O sêmen diluído em cada meio foi envasado (palhetas de 0,5ml) e congelado, e a motilidade espermática avaliada após o descongelamento (60ºC, 8seg). O sêmen foi novamente congelado em palhetas com diferentes volumes (0,25 e 0,5ml) e descongelados em banho-maria em duas temperaturas (50º e 60ºC). As maiores motilidades (48 por cento) foram observadas no sêmen diluído em BTS® e resfriado por sete dias. Motilidade espermática acima de 68 por cento foram observadas no sêmen congelado em NaCl 154mM-metilglicol, BTS®-metilglicol, NaCl 200mM-DMSO e Saad-DMSO. Não houve diferença entre os volumes de palheta nem entre as temperaturas de descongelamento quanto a motilidade espermática. Assim, o sêmen de pirapitinga mantém altas taxas de motilidade quando resfriado em BTS® por até sete dias ou congelado em NaCl 154mM-metilglicol, BTS®-metilglicol, NaCl 200mM-DMSO e Saad-DMSO

Cooling and freezing protocols of pirapitinga (Brycon nattereri) semen were evaluated using semen diluted in 154mM NaCl, 200mM NaCl, Saad or BTSÕ, and cooled for seven days. Sperm motility was daily evaluated. Five extenders (277mM glucose, 154mM NaCl, 200mM NaCl, Saad and BTSÕ) were combined with two cryoprotectants (DMSO - dimethyl sulphoxide and methylglycol) to produce 10 cryosolutions. Semen was diluted in each cryosolutions, aspirated into 0.5ml straws and frozen. Sperm motility was evaluated after thawing (60ºC, 8 sec). Then, semen was frozen in straws with different volumes (0.25 and 0.5ml), and thawed under different water-bath temperatures (50º and 60ºC). Higher sperm motility (48 percent) was observed when semen was cooled in BTSÕ for seven days. Post-thawing sperm motility above 68 percent was observed when semen was frozen in 154mM NaCl-methylglycol, BTSÕ-methylglycol, 200mM NaCl-DMSO or Saad-DMSO. There was no difference on sperm motility when semen was frozen in 0.25 or 0.5ml straws and thawed in 50º or 60ºC water-bath. Thus, pirapitinga semen can be successfully cooled in BTSÕ for seven days or frozen in 154 mM NaCl-methylglycol, BTSÕ- methylglycol, 200mM NaCl-DMSO and Saad-DMSO

Vascular and glomerular effects of Clostridium difficile toxin A peptide on the isolated rat kidney

Toxin A peptide from Clostridium difficile caused damage and secretion in the intestinal mucosa. These effects are mediated in part by pro-inflammatory substances. In order to evaluate and compare the biologic effect of toxin A on renal vascular, glomerular and tubular functions, we studied this toxin in isolated rat kidneys. Isolated kidneys from adult male Wistar rats (260-320 g) were perfused with Krebs-Henseleit solution containing 60 mg/ml dialyzed bovine serum albumin. We studied the effect of toxin A peptide (3.2 x 10(-6) M, injected into perfusate) on glomerular filtration rate (GFR), urinary flow rate (UF) and total sodium reabsorption (TNa+, per cent ). All experiments were preceded by a 30-min basal period, and in another group of kidneys the time course of the variables was followed without toxin infusion for unpaired control. Toxin A (TxA) reduced the perfusion pressure (PP), from PPcontrol/30min = 124.89 +/- 1.91 to PPTxA/120min = 88.13 +/- 5.1 mmHg (N = 6, P < 0.01) with a maximal effect at 120 min after toxin infusion. TxA also caused a significant decrease in GFR with maximal effect at 90 min after toxin infusion (GFRcontrol/30min = 0.53 +/- 0.05 to GFRTxA/90min = 0.30 + 0.05 ml min-1g-1; N = 6, P < 0.01). TxA did not alter renal tubular sodium transport when compared with a control without toxin infusion. In addition, toxin-treated kidneys caused a time-dependent increase in urinary flow from UFcontrol/30min = 0.16 +/- 0.08 to UFTxA/120min = 0.35 +/- 0.1 ml min-1g-1 (N = 6, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sex hormones on gentamicin-induced nephrotoxicity in rats

1. There is clinical and experimental evidence that females are more susceptible to gentamicin-induced nephrotoxicity. To assess the role of sex as a risk factor in aminoglycoside-related acute renal failure 16 groups of five 120 +/- 15-day old (young adult) Wistar rats of both sexes, castrated and non-castrated, were treated with gentamicin. These rats were medicated with 40 mg kg-1 24 h-1 gentamicin alone for 10 days. Some animals received gentamicin after 5 days of treatment with depot testosterone or estrogens. 2. Blood urea and creatinine levels before and after gentamicin administration were measured to evaluate renal function. Histological lesions were studied by light microscopy by two pathologists who were unaware of the group. Rats with normal or elevated levels of estrogens showed functional impairment after gentamicin. A poor correlation was detected between levels of urea/creatinine and histopathological findings. 3. Lesions were considerably more severe in females. Testosterone administration to intact animals offered partial protection against the renal effects of gentamicin in both sexes. In contrast, estradiol administered to intact animals was regularly associated with significantly more severe lesions in both males and females. Castration by itself attenuated the gentamicin-induced renal alterations in males, but not in females. These data provide support for an unfavorable effect of estrogens rather than a favorable effect of testosterone. The demonstration of more severe lesions in female castrated rats when compared with male castrated rats indicates the participation of other factors, possibly of a genetic nature, in the pathogenesis of gentamicin-induced renal lesions