Qualitative parameters of the piapara semen (Leporinus elongatus Valenciennes, 1850)

Sperm characteristics, peroxidation lipid and antioxidant enzyme activity changes in milt of Brycon orbignyanus cryopreserved with melatonin in different freezing curves

The objective of this study was to evaluate extender supplemented with melatonin and freezing curves on the antioxidant enzyme activity, peroxidation lipid and sperm characteristics of cryopreserved Brycon orbignyanus milt. Males (n = 16) and females (n = 5) were hormonally induced with two doses (0.5 mg and 5.0 mg kg^-1) of carp pituitary extract, and their gametes were collected by light abdominal massage. The fresh milt was diluted at a ratio of 1:4 (milt:extender) in the following solutions: (Control) 10% methyl glycol (MG) + 5% Beltsville thawing solution; (M1) Control + 1 mM melatonin; and (M2) Control + 2 mM melatonin. The freezing curves were C1 (automated freezer) and C2 (dry shipper for 24 h). After each curve was recorded, the straws were transferred to a liquid nitrogen container until the analyses were performed. The samples were thawed in a water bath (60 °C, 8 s) and evaluated using the Sperm Class Analyzer software for the parameters total motility, progressive motility, curvilinear velocity, straight line velocity, mean displacement velocity, straightness, and linearity. The following were also measured: motility time, vitality, morphology, oxidative stress (lipid peroxidation, activity of catalase and superoxide dismutase, quantification of nitric oxide), and fertilization and hatching rates. The data were analyzed within R by one-way analysis of variance and Tukey's test for comparison of means (p < 0.05). A significant difference (p < 0.05) was observed between the solutions in vitality, morphology, motility, and fertilization rate, the solutions with melatonin having the best values. Total motility, progressive motility, and motility time were significantly different. Among oxidative stress markers, only lipid peroxidation and superoxide dismutase activity showed an effect of the curve × solution interaction (p < 0.05), the solutions with melatonin yielding the lowest values. The fertilization and hatching rates were also higher under the melatonin treatments, regardless of the curve. Melatonin 2 mM and slow curve are indicated for the cryopreservation of fish species sperm as it led to the slowest detrimental spermatozoa effects and better fertilization and hatching rates.

Effect of melatonin supplementation to a cytoprotective medium on post-thawed Brycon orbignyanus sperm quality preserved during different freezing times

The aim of the present study is to verify the viability of frozen B. orbignyanus sperm cells after freezing with dilution media containing different concentrations of the melatonin and after different freezing times. Semen from 15 males was collected and pooled as five pools from three random animals. Oocytes (100) from three females were separately used for fertilization. There were three treatments: (C) Control Medium: 90% of extender Beltsville thawing solution (5% concentration) + 10% methylglycol (MG); (M1) Control Medium + 1 mM melatonin; and (M2) Control Medium + 2 mM melatonin. Sperm samples were diluted in media at a final proportion of 1:4 [125 μl sperm (25% V/V) + 337.5 μl BTS (65% V/V) + 37.5 μl MG (10% V/V)]. Melatonin was added at final solution. Three Dry shipper freezing times were used: T1 (15 min), T2 (12 h) and T3 (24 h). The samples were transferred, stored in a cryobank and thawed in a water bath at 60 °C for 5 s and evaluated concerning viability, morphology and fertilization rate. B. orbignyanus semen frozen in M2 presented the highest fertilization rate (8.40 ± 2.54%). The highest vitality (85.2 ± 2.8%), motility (64.63 ± 8.3%), motility duration (84.22 ± 11.4 s) and progressive motility (17.01 ± 1.2%) rates were maintained for M2. The highest number of altered cells was observed in C (57.4 ± 5.9%). Melatonin at 2 mmol L^-1 associated with the cryoprotectant methylglycol in cryopreservation could be used to improve a cryobank for endangered Brycon orbignyanus populations.

Leporinus elongatus induced spawning using carp pituitary extract or mammalian GnRH analogue combined with dopamine receptor antagonists

Several studies have been developed to support the replacement of the crude carp pituitary extract (CPE) by synthetic products for induced reproduction of South American rheophilic species. However, results have been quite heterogeneous and there is no consensus or a routine use of synthetic products in these species. Thus, the aim of this study was to evaluate the ovulatory process in L. elongatus using different protocols of hormonal induction. Thus, fifteen wild mature females maintained at the Experimental Fish Station, Salto Grande, SP, Brazil were submitted to three different hormonal treatments: CPE (fractioned dose: 0.5 and 5.0 mg kg^-1); mGnRHa (single dose: 3.5 µg kg^-1) and mGnRHa (single dose: 5.0 µg kg^-1). The spawning rate and absolute fecundity were similar among the treatments, but fertility rates were higher for CPE treatment (23.60 ± 9.40) then for mGnRHa treatments (close to or zero zero). Although females ovulated in all treatments, none of them provided viable embryos, showing hatching rates close to zero or zero. Both mGnRHa treatments were more potent for inducing the ovulatory process then CPE treatment, which was evidenced by the fact that the formers showed higher volume density of postovulatory follicles (POF). Accordingly, E₂ and 17α-OHP plasma levels were higher for the mGnRHa treated females compared to the CPE one at the time of ovulation. In this study we confirmed previous scientific evidence that, regardless of whether promoting ovulation, the use of conventional CPE and GnRH doses are not appropriate for some South American migratory species, due to the non-attainment of viable embryos. Moreover, we have brought new information about the relationship between reproductive performance and gonadal steroids concentrations using different hormonal therapies, contributing to understand the reasons for Leporinus elongatus embryo loss in induced spawning.

Quantitative and qualitative variables of semen from surubim do Iguaçu, Steindachneridion melanodermatum Garavello, 2005 (Siluriformes: Pimelodidae)

The objective of the present work was to assess the qualitative and quantitative characteristics of semen from the surubim do Iguaçu (Steindachneridion melanodermatum). Induced spermiation was achieved in eleven males with mean weight of 1.76 ± 0.48 kg and average age of two years and semen was collected by stripping. The average volume was 1.34 ± 0.73 mL. The duration of sperm motility was 154.4 ± 72.6 and 149.0 ± 77.5 seconds after activation with hatchery water and distilled water, respectively. The sperm concentration estimated by hemocytometer was 5.423 ± 2.155 x 1010 spermatozoa/mL. The results indicate that S. melanodermatum semen is easily obtained during the spawning season and the seminal characteristics are adequate insemination and subsequent in vitro fertilization.

Different expression patterns of sperm motility-related genes in testis of diploid and tetraploid cyprinid fish†

Sperm motility is an important standard to measure the fertility of male. In our previous study, we found that the diploid spermatozoa from allotetraploid hybrid (4nAT) had longer durations of rapid and slow progressive motility than haploid spermatozoa from common carp (COC). In this study, to explore sperm motility-related molecular mechanisms, we compared the testis tissues transcriptomes from 2-year-old male COC and 4nAT. The RNA-seq data revealed that 2985 genes were differentially expressed between COC and 4nAT, including 2216 upregulated and 769 downregulated genes in 4nAT. Some differentially expressed genes, such as tubulin genes, dynein, axonemal, heavy chain(dnah) genes, mitogen-activated protein kinase(mapk) genes, tektin 4, FOX transcription factors, proteasome genes, and ubiquitin carboxyl-terminal hydrolase(uchl) genes, are involved in the regulation of cell division, flagellar and ciliary motility, gene transcription, cytoskeleton, energy metabolism, and the ubiquitin–proteasome system, suggesting that these genes were related to sperm motility of the 4nAT. We confirmed the differential expression of 12 such genes in 4nAT by quantitative PCR. By western blotting, we also confirmed increased expression of Uchl3 in 4nAT testis. In addition, we identified 1915 and 2551 predicted long noncoding RNA (lncRNA) transcripts from testis tissue transcriptomes of COC and 4nAT, respectively. Of these, 1575 lncRNAs were specifically expressed in 4nAT and 939 were specifically expressed in COC. This study provides insights into the transcriptome profile of testis tissues from diploid and tetraploid, which are useful for research on regulatory mechanisms behind sperm motility in male polyploidy.

Gonadorelin increases semen production and does not affect its quality in Leporinus obtusidens

Use of carp pituitary extract (CPE) as a hormone inducer for Leporinus obtusidens is cost-prohibitive; moreover, CPE contains unknown concentrations of gonadotropins. We evaluated the efficacy of gonadorelin as a substitute by analyzing its effect on sperm characteristics of L. obtusidens and cost-effectiveness (20, 40, 60, 80, and 100μgkg^-1). Untreated and CPE-treated (4mgkg^-1) fish were used as negative and positive controls, respectively. Following a single intramuscular dose of hormones, semen was collected at 200°-h. At doses from 60μgkg^-1, all fish produced higher milt volume (P<0.05) than the negative control (0.2-0.8mLkg^-1), equal (P>0.05) to the positive control (3.52±0.97mLkg^-1). Gonadorelin did not affect sperm concentration (P>0.05). The percentage of morphologically normal spermatozoa was >64% in all treatments. The number of spermatozoa with intact membrane (70%-85%) was equal (P>0.05) to that in the controls. Relative to the negative control, gonadorelin did not affect the motility rate (P>0.05). Curvilinear velocity was equal (P>0.05) to that in both controls. The sperm swimming path was linear (0.9) 10s after activation and was not (P>0.05) dose-dependent. Considering the response rate of gonadorelin-induced fish and the similarity of semen quality compared to controls, the lowest effective dose to produce a higher volume of semen in L. obtusidens is 60μgkg^-1, and the cost to induce 1kg of L. obtusidens is 14.0% lower than that with CPE.

AS, Corcini CD, Streit Jr. DP. Functional integrity of Colossoma macropomum (Cuvier, 1816) sperm cryopreserved with enriched extender solutions

Cryoprotectant solutions are used to protect the sperm from alterations caused by the low temperature in the cryopreservation process. We evaluated the quality of Colossoma macropomum semen after freezing, using dimethyl sulfoxide (DMSO) as a cryoprotectant, combined with two extender solutions (T1 - Solution 1: Glucose 90.0 g/L, Sodium Citrate 6.0 g/L, EDTA 1.5 g/L, Sodium Bicarbonate 1.5 g/L, Potassium Chloride 0.8 g/L, Gentamycin Sulphate 0.2 g/L, and T2 - Solution 2: Glucose 90.0 g/L, ACP(r)-104 10.0 g/L). Motility rate and motility time did not differ between T1 and T2 and were lower than fresh semen. The number of normal sperm was significantly different in treatments T1 (15.1%) and T2 (21.9%), and both showed a reduction in the percentage of normal sperm compared to fresh semen (57.4%). The values found for the rates of fertilization and hatching, mitochondrial functionality and sperm DNA, did not differ between the treatments (T1 and T2). Regarding membrane integrity, there was a higher percentage of spermatozoa with intact membranes in T1 (53.4%) than T2 (43.7%). The extender solutions, combined with 10% DMSO, maintained the sperm DNA intact in almost all the C. macropomum sperm cells, however there was a loss in their functionality.

Hormonal induction of Brycon cephalus (Characiformes, Characidae) to spermiation using D-ala6, pro9net-mGnRH + metoclopramide

This study aimed to establish a hormonal induction protocol for spermiation of Brycon cephalus males, using Ala6, Pro9Net-mGnRH + metoclopramide (Ovopel®). Thus, 20 males were used divided into three inductor treatments [⅓ pellet/kg (T1), ⅔ pellet/kg (T2) and 1⅓ pellet/kg (T3)] and one control group (CO), which only received physiological solution applications (0.9% NaCl). All treatments were applied in a single dose. For evaluation of the availability of the treatment, the following seminal parameters were analyzed: seminal volume, subjective spermatic motility, duration of motility, pH, osmolality and spermatic concentration. T3 showed the highest seminal volume (4.66 ± 1.52 ml), and was significantly different in comparison with T1 (2.0 ± 0.9 ml), T2 (3.5 ± 1.3 ml) and CO (2.3 ± 1.2 ml). In relation to spermatic motility, T2 and T3 showed significantly higher levels [5, (81–100%)]. However, T3 showed significantly lower average sperm motility duration than T1, T2 and CO (30 ± 7 s; 28 ± 6 s; 32 ± 8 s, respectively). With regard to the seminal parameters of spermatic concentration, pH and osmolality, no significant variation was verified among treatments. In conclusion, mGnRH + metoclopramide used for hormonal induction of B. cephalus reproduction does not induce changes related to spermatic concentration, pH and osmolality parameters of the seminal fluid and the most adequate doses among tested treatments were ⅔ pellet/kg live fish.

Hormonal induction and semen characteristics of tambaqui Colossoma macropomum

In the hatchery-bred tambaqui Colossoma macropomum, spontaneous semen release does not occur, and hand-stripping produces reduced semen volume. The goal of this work is to evaluate the effects of hormonal induction with carp pituitary extract (CPE) on both qualitative (visual aspect, pH, motility, viability and morphological abnormalities) and quantitative (volume, concentration and number of spermatozoa per ejaculate) traits of tambaqui semen. Eleven males were treated with CPE (induced), and 11 were left untreated as a control (non-induced). All analysed parameters except motility and percentage of viable spermatozoa presented significant differences (p < 0.05) between the induced and non-induced treatments. CPE induction resulted in a 25-fold increase in semen volume and a 10-fold increase in the number of spermatozoa collected. However, both sperm concentration and the frequency of sperm with morphological abnormalities (commonly detached heads or bent tails) were significantly lower in CPE-induced fish. The hormonal induction of tambaqui males with CPE is efficient and positively influences some qualitative and quantitative properties of semen. Additionally, semen collection via gentle abdominal massage occurs more readily in CPE-induced fish.