Quantity, motility and fertility of tench Tinca tinca (L.) sperm in relation to LHRH analogue and carp pituitary treatments

The spermiation of tench males was stimulated with Supergestran containing mammalian LHRHa lecireline at the following doses: 5, 10, 20 and 40 g kg⁻¹ b.w.; then with carp pituitary suspension (CPS) at a dose of 2 mg kg⁻¹ b.w. and with a control of saline physiological solution. The following days, meaning 24, 48 and 72 h after injection, sperm was collected to evaluate volume and the number of sperm per male per kg body weight (B.W.) The percentage of motile sperm and velocity of spermatozoa were measured 48 h after hormonal injection, and 72 h after hormonal injection the sperm was evaluated for fertilization and hatching ability. All 42 males in experimental groups were diploid. Live weight did not differ significantly among experimental groups. The strongest stimulation of spermiation was achieved with LHRHa in dosage of 20 and 40 g kg⁻¹ b.w. and CPS compared to males of the control group and lower dosage of LHRHa. Analysis of variance showed no significant influence of the treatment on the velocity and percentage of motile spermatozoa. The effect of different treatment on the fertilization capacity (the number of spermatozoa per egg was equilibrated) was significant. Significantly the highest quality of sperm collected 72 h after injection expressed by percentage of fertilization and hatching (62–65% fertilization and 61–64% hatching rates, respectively) was found for LHRHa in dosage of 20 and 40 g kg⁻¹ b.w. Significantly the lowest parameters of fertilization and hatching were found for the control group, on the 12% level.     

Physio-Chemical Characteristics of Seminal Plasma and Development of Media and Methods for the Cryopreservation of European eel Sperm

The high sperm density, together with the short spermatozoa swimming time, makes European eel sperm manipulation and assessment for quality difficult. Two diluting media (K15 and K30) previously designed for Japanese eel sperm were tested. After 24 h, European eel sperm showed significant reduction in the percentage of motile spermatozoa after activation and different motility parameters (VAP, angular velocity; VCL, curvilinear velocity; VSL, straight line velocity; BCF, beating cross frequency), concluding that these media are not suitable to preserve the sperm of this species. After a hormonal treatment to induce spermiation, sperm volume, density and motility were recorded at weekly samplings. The variation of the osmolality (325–330 mOsm kg⁻¹), pH (8.4–8.6) and the ionic composition (concentration of Na⁺, K⁺, Mg²⁺ and Ca²⁺) of the seminal plasma were registered. Physio-chemical results were related with sperm quality throughout the treatment, to determine which must be the suitable characteristics of one extender for the sperm of this species, and to find the best conditions to obtain suitable cryopreservation media for European eel sperm. K⁺ concentration increased, while Ca²⁺ and Mg²⁺ concentrations showed a progressive reduction in correlation with the sperm quality improvement. Na⁺ showed a decreasing, but not significant tendency. P1 and P2 freezing media were designed considering the physio-chemical parameters as well as the ionic composition shown by the best quality sperm samples, and then compared with the previously described solutions, TNK and K30. Sperm quality was determined, checking the percentage of motile spermatozoa and motility parameters using computer-assisted sperm analysis (CASA) software. Samples were frozen after dilution (1:5, 1:20, 1:100) in different freezing media supplemented with 10% dimethyl sulfoxide (DMSO). After thawing, samples frozen with low dilution ratio (1:5) in TNK and P1 media showed higher, although not significant, spermatozoa survival (35.5 ± 14.5 and 36.6 ± 6.7%). The addition of l-α-phosphatidylcholine to the media seems to have a positive effect, as reported in the Japanese eel.     

Studies on sperm of diploid and triploid tench, Tinca tinca (L.)

The tench Tinca tinca is an interesting fish from the viewpoint of polyploidy and related atypical reproduction aspects. Triploid tench were produced artificially. Studies of spermiation as well as of sperm motility and structure were performed on several triploid and diploid males simultaneously with individual experimental crosses with diploid females to define their reproductive capacities. The testes of triploids visually looked less developed in the most of cases with lower sperm production (0.05 cm³ sperm per male), GSI and weight of testes compared to diploids (0.58 cm³ sperm per male). Analysis of variance showed significant influence of ploidy level on the percentage of motile spermatozoa. Triploidy did not change percentage of live spermatozoa and velocity of spermatozoa at the first time of sperm movement. The study of sperm structure by scanning electron microscopy revealed that most sperm cells were of normal structure with some anomalies. Sperm heads of triploid and diploid males were mostly round-shaped, 1.86±0.2 and 1.6±0.18 μm in diameter. The midpiece of triploid spermatozoa was slightly narrower than that of diploid ones with typical cylindrical shape. Flow cytometry revealed sperm cells of triploids to be largely aneuploid (1.47 n) with high mosaic DNA, oscillating from haploid DNA content (1.0 n) to diploid DNA content (1.9 n). Experimental crosses between triploid males and diploid females revealed that these males were capable to stimulate effective development with relatively high level of fertilization and hatching rates from 0 to 70%. In conclusion, triploidization does not seem to guarantee sterility of tench.     

Induced spermiation in 3-year-old sterlet, Acipenser ruthenus L.

Spermiation in 3‐year‐old sterlet, Acipenser ruthenus (L.), males maintained under warm water conditions was induced by intramuscular injection of either (i) (D‐Ala⁶)‐GnRH‐ProNHEt (Kobarelin); (ii) mammalian GnRH analogue+metoclopramide (Ovopel); or (iii) human chorionic gonadotropin (Biogonadyl). The volume of milt, sperm concentration and motility were measured. A higher percentage of spermiating males was obtained after Kobarelin or Ovopel treatment (81.8% and 77.7% respectively) in comparison with fish treated with Biogonadyl (40.0%). However, only stimulation with Ovopel guaranteed motile spermatozoa in all spermiating males. Moreover, treatment with Ovopel resulted in the highest average milt volume, sperm concentration and motility. The average total number of motile spermatozoa (milt volume×sperm concentration×sperm motility) per individual was 0.99×10⁹, 5.31×10⁹ and 0.02×10⁹ after stimulation with Kobarelin, Ovopel or Biogonadyl respectively. Our data indicate that Ovopel is a good stimulator of spermation in sturgeons. Moreover, the time of sexual maturation could be significantly reduced in sturgeons maintained in cages under warm water conditions.     

Effects of hormonal manipulation on stress responses in male and female broodstocks of pikeperch Sander lucioperca

This study was designed to determine the effects of hormonal manipulation on stress responses in female and male pikeperch. Two-year-old cultured female and male broodstocks with an average weight of 337.4 ± 20.1 (mean ± SE; n = 16) and 318.7 ± 15.1 g (n = 16), respectively, were randomly allocated into four hormonal treatments each containing 4 fish. Two sexual groups of 16 fish for each gender were considered. Sexually mature male and female pikeperch were injected with either physiological saline solution (as control group), common carp pituitary extract (CPE), human chorionic gonadotropin (hCG) and or luteinizing hormone-releasing hormone analog (LHRHa₂). The blood samples were taken before hormonal injection and after ovulation and spermiation. Then the plasma levels of stress indices (cortisol, glucose, and lactate) were determined. The results showed that all CPE-, HCG-, and LHRHa_2- injected males produced sperm. In females treated with CPE and hCG, three of four ovulated, but none of LHRHa_2- and saline-injected fish spawned. Significant changes in cortisol, glucose, and lactate levels were observed among the females injected with different hormones. Plasma cortisol and glucose levels increased significantly in males injected with CPE and females injected with hCG, but no significant change was observed in lactate levels before and after hormonal induction. Comparison of two sexes revealed significant differences in glucose levels for females in some groups before injection, while CPE-injected sexes showed significant changes in cortisol and lactate concentrations. The results indicated that the induction of ovulation or spermiation stimulated stress responses especially in female pikeperch, and therefore, all the procedures should be made to minimize the disturbance during the artificial spawning.     

Sperm characteristics and androgens in Acipenser ruthenus after induction of spermiation by carp pituitary extract or GnRHa implants

Spermiation and changes in androgen (testosterone, T and 11-ketotestosterone, 11-KT) levels were studied in sterlet (Acipenser ruthenus) treated with GnRH agonist implants (dAla⁶-Pro⁹-LHRHa) at 25 and 75?μg?kg^?1 b.w. and compared with those males treated with 4?mg?kg^?1 b.w. of carp pituitary extract (CPE) and 3 pellets of Ovopel kg^?1 b.w., which contains dAla⁶-Pro⁹NEt-mGnRH and metoclopramide. Sperm quality (sperm mass, spermatozoa concentration and sperm motility and velocity) was evaluated 24, 48 and 72?h after hormonal treatments. Males did not release sperm in the control group injected with physiological solution, while sperm could not be collected 7?days after treatments in all hormonally treated groups. Spermiation rates were 100?% in the CPE and Ovopel groups and 25–50?% in the GnRHa-treated groups. Sperm production was significantly lower in the GnRHa-treated groups than in the CPE and Ovopel groups and decreased 72?h after hormonal treatment. Sperm motility and velocity were higher in the Ovopel and GnRHa (75?μg) groups compared to the CPE and GnRHa (25?μg) groups and decreased 72?h after hormonal treatment. Androgens were only affected in spermiating males and changed in the Ovopel and GnRHa (75?μg) after hormonal treatment. Significant correlations were observed between sperm production, sperm motility and sperm velocity, but not androgens. The present study suggests involvement of dopamine in sturgeon spawning. Additionally, better sperm quality observed in the Ovopel group and particularly sperm motility in the GnRHa (75?μg) suggests enhancement of sperm quality in sturgeon treated with GnRHa. Therefore, further study is needed to induce fully spermiation using GnRHa implants in combination with a dopamine inhibitor.     

Characterization of Senegalese sole, Solea senegalensis, male broodstock in terms of sperm production and quality

Sperm quality and production have never been characterized in Solea senegalensis males. Reproduction in captivity in this species has been obtained mostly with wild-captured animals, because it is common that the F1 generation fails to reproduce. However, there is no information on sperm quality from both types of broodstocks. The aim of the present study was to characterize sperm production and to describe the profiles of spermiation in individual wild-captured males. Also, sperm quality and production were determined in two types of broodstocks established in our facilities; wild-captured and F1 individuals. The males were analyzed for their fluency and identified as fluent or non-fluent. The sperm volume, cell concentration, sperm production and motility were recorded from mid February until mid November in both broodstocks. Results showed that S. senegalensis males can produce motile sperm during all this period, with specific peaks of high spermiation and a high percentage of fluent males. This fact was observed in both male broodstocks. There was a large variability in terms of sperm profiles in males maintained under the same conditions. Sperm volume collected in this species was very small and ranged from 5 to 20 μl in F1 broodstock and 10 to 80 μl in wild-captured broodstock. Cell density ranged from 0.7 to 1.2 × 10⁹ spermatozoa/ml in F1 males to values of 1-2 × 10⁹ spermatozoa/ml for the wild-captured males. Sperm production (total spermatozoa per stripping) was also very low and ranged from 20 × 10⁶ spermatozoa for F1 broodstock to 40-60 × 10⁶ spermatozoa for wild-captured broodstock. Our results demonstrated that sperm production in this species is very low and variable according to the type of males. These results suggest that a previous selection of males according to their fluency, sperm production and provenience (wild-captured or F1) should be taken into account in the establishment of a S. senegalensis broodstock.     

Spermiation of paddlefish (Polyodon spathula,Acipenseriformes) stimulated with injection of LHRH analogue and carp pituitary powder

The potential of carp pituitary powder (CPP) at one dose, or the luteinizing hormone-releasing hormone (LH-RH) analogue, des–Gly¹⁰,(d–Ala⁶)–LH-RH–ethylamide, at three different doses to stimulate spermiation in paddlefish (Polyodon spathula) was tested. Single injections of the LH-RH analogue at 0.2, 0.1, or 0.05 mg·kg^–1 increased the number of spermatozoa per kilogram of body weight (kg^–1 b.w.) by 4.7, 3.4, and 3.4 times respectively compared to control, but the number of spermatozoa per kilogram of body weight decreased with CPP (4 mg·kg^–1) by 1.7 times compared to the control. The LH-RH analogue prolonged active spermiation, with numbers of spermatozoa ranging from 7.69 to 1.19 × 10⁹ kg^–1 b.w. up to 96 h after treatment. Analysis of variance showed significant influence of experimental groups on volume of sperm per male and per kilogram of body weight, and the total number of spermatozoa per kilogram of body weight, but insignificant influence on the total number of spermatozoa per male. The percentage of motile spermatozoa was not different between experimental groups for sperm collection at different times after injection. A very high positive correlation (r = 0.93) was obtained between sperm concentration and sperm transmittance measured with a spectrophotometer. This relationship was described with the following linear regression: sperm concentration (× 10⁹ mL^–1) = 1.3244 X^–0.9969, where X is the percentage of sperm transmittance.     

The Cryopreservation of Striped Bass Morone saxatilis Semen

Abstract.— Two experiments were designed to improve upon existing methods for cryopreserving striped bass Morone saxatilis , semen. In the first experiment, two extenders, two cryoprotectant concentrations, and two freezing rates were evaluated on the basis of post-thaw semen motility after 1, 7, and 30 d of storage at −196 C. Semen samples cryopreserved at a freezing rate of −40 C/m resulted in a significantly higher percentage of motile sperm ( P < 0.001) and longer duration of spermatozoa motility ( P < 0.001) than samples cryopreserved at a freezing rate of -30 Chin. Also, the cryoprotectant dimethyl-sulfoxide yielded a significantly higher percentage of motile sperm ( P < 0.001) and longer duration of spermatozoa motility ( P < 0.001) when a 5% concentration was used instead of 7.5%. In the second experiment, the two extenders from Experiment I were re-evaluated and a new extender, which was a modified version of Extender 1, was tested. The samples were cryopreserved at -40 C/min with 5% DMSO and thawed in a 25 C water bath. Spermatozoa motility and fertilization ability were evaluated, and semen cryopreserved in Extender 2 yielded the longest duration of spermatozoa motility ( P < 0.001). the highest percentage of motile sperm ( P < 0.001). and the highest percentage of fertilized eggs ( P < 0.002) in comparison to Extenders I and 3.     

Effect of two commercial preparations containing different GnRH analogues with dopamine antagonists on barbel Barbus barbus (L.) sperm quantity and quality

The effectiveness of applying Ovaprim [(D-Arg⁶, Pro⁹NEt)-sGnRH + domperidone] and Ovopel [(D-Ala⁶, Pro⁹NEt)-mGnRH + metoclopramide] to male barbel Barbus barbus (L.) 6, 12 and 24 h after hormonal stimulation was analyzed. The control group (Control) during each time interval was stimulated with 0.9 % NaCl. Milt was collected from seven fish only once (n = 7) for Ovopel, Ovaprim and Control group in order to determine total volume of milt, volume of milt per kg of body weight, sperm concentration, total sperm production, seminal plasma osmotic pressure, pH of milt and pH of seminal plasma. Woynarovich’s solution (68 mM NaCl + 50 mM urea) with the addition of 0.5 % BSA (pH 7.7; 181 mOsm kg^?1) was used as the activating liquid. Selected parameters of sperm motility (MOT %) and progressively motile sperm (%), curvilinear velocity (VCL, μm s^?1), straight-line velocity (μm s^?1), movement linearity (%), wobbling index (%), amplitude of lateral head displacement (μm) and beat cross frequency (Hz) were determined using the Computer-assisted sperm analysis system. A time of 6 h proved to be too short to obtain milt from barbel following hormonal stimulation with Ovaprim and Ovopel. Extending the time to 12 h, however, resulted in 100 % spermiation in males, regardless of hormonal preparation used for stimulation. The stimulation of spermiation in barbel is best performed using Ovopel 12 h upon application. Extending the latency period to 24 h following the application of this preparation results in a significant decrease in the volume of milt obtained, sperm count and motility parameters, including MOT and VCL, which may influence sperm fertilization ability.     

Semen biology and stimulation of milt production in the European smelt (Osmerus eperlanus L.)

Basic characteristics of the European smelt (Osmerus eperlanus) sperm are reported here for the first time. Smelt spermatozoa had a bullet-shaped head (1.42 μm length), a short midpiece and a long flagellum (27.72 μm). Two mitochondria were located along the flagella. The volume of smelt sperm was small (30-60 μl) and the duration of sperm motility was short (22 s in distilled water and 41 s in 20 mM sodium bicarbonate solution). Sodium chloride at concentrations ranging from 0-120 mM did not influence the percentage of motile spermatozoa but caused a steady increase in the duration of sperm movement. Potassium ions clearly reduced the percentage of motile sperm at a concentration of 10 mM. Spermatozoa were motile through a broad range of pH with an optimum from 7.5 to 8.5. Testicular spermatozoa had a different motility pattern compared to stripped spermatozoa (the latter exhibiting a reduction of motile spermatozoa by 30%, lower ALH and VCL and higher LIN and VSL). These results indicate that maturation of smelt spermatozoa occurring in sperm ducts is related not only to an increase of the percentage of motile spermatozoa but also to changes in the sperm motility pattern. Maintaining males with females resulted in stimulation of milt production. Our results indicate that European smelt sperm characteristics are similar to those of ayu (Osmeridae).     

Age-Related Sperm Quality of Captive Striped Bass Morone saxatilis

Three groups of captive-reared striped bass Morone saxatilis ages 1, 3 and 12 yr, were examined for age-related changes of sperm characteristics including short-term storage. All groups had similar ranges of the following parameters (mean× SEM): expressible milt (5.6× 0.5 mI/kg body weight (BW) to 7.5× 2.1 mL/kg BW), percentage of motile sperm (55× 6% to 60× 2%), duration of sperm motility (69× 3 sec to 72× 5 sec) and percentage of viable sperm (91× 2% to 93× 2%). Compared to the 1 and 12-yr-old fish, the 3-yr-old fish produced the greatest number of spermatozoa (1,190× 370× 10⁹ spermatozoa/kg), sperm concentration (120× 8 × 10⁹ spermatozoa/mL) and spermatocrit (74× 4%). In addition, during short-term storage at 4 C, extender-preserved sperm samples of the 3-yr-old group showed a significantly higher ( P < 0.05) percentage of motile sperm and duration of sperm motility, compared to the other two groups. This suggests that short-term storage may be affected by the age of the male fish. Sperm longevity of the 3-yr-old group was successfully maintained for as long as 15 d, longer than that of the 1-yr-old group (9 d) and 12-yr-old group (7 d). Overall, the 3-yr-old fish appeared to have superior sperm quality than the 1 or 12-yr-old fish based on higher sperm production and increased sperm longevity.     

Exposure to 17α,20β-dihydroxy-4-pregnen-3-one changes seminal characteristics in Nile tilapia, Oreochromis niloticus

This experiment was conducted to evaluate the seminal characteristics of Nile tilapia males exposed to water‐borne 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20βP). Male Nile tilapia (Oreochromis niloticus L.) were exposed to the steroidal pre‐ovulatory pheromone 17,20βP, added to water at a concentration of 5×10^?9 M. The pheromone‐exposed males had higher sperm volume and concentration. In addition, the spermatozoa contained in the sperm had higher motility and the motility duration was longer than ethanol‐exposed males (control group). The percentage of live spermatozoa was not affected by the treatments. Our results suggest that this pheromone can improve sperm quality characteristics and could become a non‐invasive method for enhancing spawning in Nile tilapia.     

Cryopreservation effects on the sperm quality of cachama blanca Piaractus brachypomus (Cuvier 1818)

The effects of straws volume, cryoprotectants and thawing temperatures were evaluated on the sperm quality of cachama blanca Piaractus brachypomus (Cuvier), an important Colombian fish species. Sexually mature fish were induced to ovulation or spermiation with a carp pituitary extract. A pool of suitable sperm samples was diluted in glucose, egg yolk, dimethyl sulphoxide (DMSO‐10%), methanol (MET‐10%) or ethylene glycol (ETG‐5%) and packed in 0.5, 2.5 or 5.0 mL straws and frozen in nitrogen vapour. The thawing process was performed in a 35 or an 80 °C water bath. The fertility was evaluated after 6 h post fertilization. The highest motility percentage (33 ± 3%) was observed with sperm cryopreserved with DMSO, packed in 5 mL straws and thawed at 35 °C. The treatments with DMSO and MET packed in 0.5 and 5.0 mL straws and thawed at 35 °C showed the highest fertility (higher than 71%) and the lowest fertility was obtained with MET‐2.5 mL (9 ± 5%). In all the treatments, a significant decrease in the sperm quality was observed at 80 °C. Sperm cryopreserved with DMSO‐10% or MET‐10%, packed in 2.5 or 5.0 mL straws are suitable to achieve acceptable fertilization and to fertilize high amounts of eggs.     

Retention of sperm motility in turbot, Scophthalmus maximus L.: the effects of time from activation, thermal shock and adenosine triphosphate levels

Abstract Four parameters were examined in order to define sperm quality in turbot Scophthalmus maximus L., sperm: (1) sperm motility, measured by direct counts of the number of active spermatozoa, expressed as % of total spermatozoa; (2) retention of motility after activation, measured by direct counts, 0–60min after activation, expressed as a % of the initial level of activity; (3) resistance to thermal stress, measured as change in retention of motility, and (4) adenosine phosphate (ATP) concentration, determined for samples of non-activated sperm. The proportion of motile spermatozoa at activation ranged from 34·8% to 97·6% (mean 76·3%) for the individual males tested. Turbot sperm retained on average 52% (range 27–90%) of its initial activity one hour after activation. Sperm samples which were stressed by cooling to –27°C retained only 8·6% (range 0–25%) of initial activity, compared to control samples which retained 49% (range 38–63%) of initial activity. The retention of motility after activation was not significantly related to the initial motility or the levels of ATP. Concentrations of ATP in turbot sperm (mean 0·46mg ATP/10⁶ spermatozoa, equivalent to 9·2nmol ATP/10⁸ spermatozoa) were comparable to those measured in mammals.     

Stimulation of spermiation and induction of ovulation in pike (Esox lucius)

Mature northern pike were given various hormonal treatments in March or April in order to stimulate spermiation or to induce ovulation. In males the total amount of sperm collected after treatment increased, in comparison with saline-injected males, by 3–11 times with partially purified salmon gonadotropin (PPSG-activity: half of the highly purified s-GTH; injected at doses of between 5 and 100 μg/kg body weight); 3–6 times with crude carp pituitary extract (0.5–3 mg/kg body weight); and 3–7 times with fresh pike pituitaries (14 and 1.2 mg wet weight/kg body weight). The sperm obtained after hormonal treatment was of good quality. Intracardiac injection of superactive LRH analogue had no effect. In females, PPSG induced 90 and 100% ovulation at the doses of 50 and 25 μg/kg body weight. Dried salmon pituitaries (2.5 mg/kg, equivalent to 50 μg of PPSG) gave 25% ovulation; at 10 mg/kg, 25% complete ovulation was again recorded, but in addition 70% of the females showed oocyte maturation and partial ovulation. Similarly, dried carp pituitary (3 mg/kg) induced only oocyte maturation but no ovulation. The oocytes obtained after hormonal treatment were in general fertile. Intraperitoneal injection of LRH in an emulsified form induced neither oocyte maturation nor ovulation. The lack of effect of LRH analogue is discussed and shows that the use of this compound as a substitute for pituitary preparation is not very promising.     

The antioxidant system of sterlet seminal fluid in testes and Wolffian ducts

Oxidative stress is a possible source of spermatozoa function deterioration. Seminal fluid (SF) protects spermatozoa against reactive oxygen species (ROS) attack during development in testes and transit through the reproductive tract. Spermatozoa curvilinear velocity and percent of motile cells as well as changes in thiobarbituric acid-reactive substance (TBARS) content, superoxide dismutase, and catalase activity, and uric acid concentration in SF were evaluated in sterlet sperm collected from testes 24 h after hormone induction of spermiation and from Wolffian ducts at 12, 24, 36, and 60 h after hormone injection (HI). While testicular spermatozoa motility was not initiated in activating medium, Wolffian duct sperm showed low motility at 12 h, significant increase at 24 and 36 h, and decrease at 60 h. Testicular SF was characterized by the highest level of TBARS and activity of studied enzymes compared with SF from Wolffian duct sperm at 24 h post-HI. In fluid from Wolffian duct sperm, a significant increase in TBARS content was shown at 36–60 h post-HI. In contrast to testicular SF, in SF from Wolffian duct sperm, this increase was not counterbalanced by changes in the studied variables of antioxidant system. This may be the source of the observed decrease in spermatozoa motility parameters 60 h post-HI. The results may confirm a dual role of ROS in fish sperm physiology. The data with respect to decrease in sturgeon spermatozoa motility parameters at 60 h post-HI should be taken into account in artificial sturgeon propagation.     

Comparative analysis of reproductive performance between spring and autumn forms of Persian sturgeon,Acipenser persicus,Bordin, 1897: with an emphasis on sex steroids and milt quality

To compare the reproductive performance of spring and autumn forms of Persian sturgeon males, Acipenser persicus, the relative abundance of spermiating and non‐spermiating males, milt quality, sex steroids and cortisol were investigated after pituitary preparation (PP) treatment and at the time of spermiation. Our results showed that higher numbers of spring males are spermiated after PP treatment than autumn individuals. The autumn spermiating males had higher and lower values of sperm density and duration of motility than spring males respectively. The milt volume was higher in spring males than in autumn individuals. The percentage of motility was statistically equal in both the groups examined. In both forms of brooders, the serum levels of testosterone (T), 11‐ketotestosterone (11‐KT), progesterone (P), 17α, 20β, 21‐trihydroxy‐4‐pregnen‐3‐one (20βS) and cortisol (C) increased after PP treatment, although such increases did not occur in non‐spermiating males. Our results showed the probable involvement of 20βs, P, T, 11‐KT and C in the final maturation of Persian sturgeon. In addition, it was demonstrated that the spring form of Persian sturgeon shows better reproductive performance than the autumn form in terms of a response to artificial induction and milt quality.     

Hormone Induced Spawning of Summer Flounder Paralichthys dentatus

During their first year in captivity, summer flounder Paralicthys denratus were induced to spawn with gonadotropin releasing hormone analogue (GnRHa) implants, injected carp pituitary extract (CPE) or human chorionic gonadotropin (hCG) injections. The percentage of fertile eggs was greatest (69%) in CPE-treated females. CPE, but not GnRHa or hCG, was capable of stimulating oocyte growth (increased follicle diameter during vitellogenesis) followed by ovulation. Fish with maximum ovarian follicle diameters between 180 and 435 μm at the initiation of CPE injections produced the greatest percentage of fertile eggs. For most females, fertilization rate was greatest for the first batch of eggs ovulated. The mean fertilization rate for the first spawn of CPE-treated fish was 42% compared with 14% for the second spawn from the same fish. Fish with maximum initial follicle diameters of 585 40 μm that were implanted with GnRHa ovulated the greatest number of eggs, but fertility was low and variable. Approximately 35% of females injected with hCG ovulated a limited number of eggs, but only one hCG-treated female produced fertile eggs. Only a limited number of spermiating males were available for spawning trials. Hormone treatments used on females were ineffective for inducing or maintaining spermiation in male summer flounder.     

Spectrophotometric determination of sperm concentration and short‐term cold‐storage of sperm in Atlantic croaker Micropogonias undulatus L. broodstock

The objective of this study was to optimize the methodology for spectrophotometric determination of sperm concentration in Atlantic croaker Micropogonias undulatus L. milt and to estimate its potential for short‐term cold‐storage. The spectrophotometric determination of sperm concentration was evaluated using milt samples from six males serially diluted in Hank's balanced salt solution at 200 mOsm kg^?1 (HBSS). The predictive power of regression models between sperm concentration and absorbance was determined from 200 to 500 nm and found to be highest within the visible spectrum despite a peak of milt absorbance at 288 nm. Absorbance reading at 400 nm was selected for further analysis to maximize the absorbance of the sample hence the sensitivity of the method while minimizing the impact of potential sample contamination with blood. The standard‐curve of correlation between sperm absorbance at 400 nm and concentration was validated and held an accuracy ranging between ?7.40% and +4.56% across males. Total sperm motility duration and the proportion of motile spermatozoa were significantly higher in milt samples diluted 1:3 in HBSS than in the undiluted control during up to 30 h of cold‐storage.The methodologies investigated in this study can be applied to optimize sperm usage and achieve predictable artificial fertilization protocols in Atlantic croaker.