Activity of aspartate aminotransferase and acid phosphatase in cryopreserved trout sperm

Optimalisation of the Activation Medium and Effect of Inhibiting Activities of Acid Phosphatase, Lactate Dehydrogenase and β-N-Acetylglucosaminidase on the Fertilisation Success of Eurasian Perch (Perca fluviatilis L.)

Simple Summary

The purpose of this study is to determine the composition of the optimal activating solution for activating sperm motility and perch eggs, because scientific studies and reproductive procedures should be conducted in stable and repeatable conditions. We found that the best activating solution was composed of 80 mM NaCl, 20 mM KCl, 10 mM Tris, with pH 8.0 and 206 mOsm/kg. In spite of this, we also checked the influence of adding the enzyme inhibitors, such as ammonium molybdate–acid phosphatase inhibitor, gossypol – lactate dehydrogenase inhibitor and acetamide–β-N-acetylglucosaminidase inhibitor on perch sperm motility and successful perch fertilisation. We showed that the addition of acid phosphatase inhibitor in perch semen did not affect the process of fertilisation; in contrast, the addition of lactate dehydrogenase and β-N-acetylglucosaminidase inhibitors significantly decreased the percentage of perch fertilised eggs.

Abstract

Although methods for the artificial reproduction of perch have been developed, a lack of information remains regarding the enzymes present in its semen, as well as their role in the fertilisation process. In this study, we first select the optimal activating solution for perch fertilisation and then determine the inhibition effect of enzymes that have already been reported as present in the sperm of teleosts—acid phosphatase (AcP), lactic dehydrogenase (LDH) and β-N-acetylglucosaminidase (β-NAGase)—on the percentage of motile spermatozoa and fertilised eggs. Of the 8 studied activation media, a solution composed of 80 mM NaCl, 20 mM KCl, 10 mM Tris, with pH 8.0 and 206 mOsm/kg proved to be optimal for perch gametes. The addition of ammonium molybdate (AcP inhibitor) caused no significant reduction in the percentage of fertilised eggs. On the other hand, the addition of 0.25 mM gossypol (LDH inhibitor) and 0.125 M acetamide (β-N-acetylglucosaminidase inhibitor) significantly decreased the fertilisation percentage to 41.1% and 52.4%, respectively, in contrast to the control (89.9 %). Both LDH and β-NAGase thus seem to play a very important role in the perch fertilisation process.

Sperm quality in fish: Determinants and affecting factors

Fish sperm quality assessment is helpful for optimizing production and for monitoring the environmental state. Sperm can be monitored relatively easy and, to date, various analyses have been applied and proven to be helpful in this task. Among them, sperm motility parameters such as sperm speed are one of the main performance traits during assisted fish reproduction. Apart from motility the sperm concentration, volume, and seminal plasma pH and osmolality are also frequently evaluated and are the main sperm quality indicators measured in fish sperm. However, other parameters also determine sperm fertilization potential. Recent knowledge reveals several additional parameters of high importance for sperm function. Among them are DNA integration, membrane stability, mitochondria status and enzymatic activity. Measuring all these parameters in fish sperm provides complex knowledge regarding male fertility and helps to improve broodstock maintenance protocols as well as gamete handling and fertilization processes. This review focuses on the presentation of the sperm quality measures for freshwater and marine species of the fish and provides information regarding recent methods of sperm quality evaluation.

Changes in sperm parameters of sex-reversed female mandarin fish Siniperca chuatsi during cryopreservation process

This works studies the physiological characteristics (sperm motility characteristics) and biochemical characteristics (DNA damage, enzymes activities and fertilization ability) of fresh and freeze-thawed semen of sex-reversed female mandarin fish Siniperca chuatsi (n = 30) obtained with the application of 17α-methyl testosterone for sex reversal. The fresh sperm motility and fertilization rate of sex-reversed females were about 83% and 70% respectively which had no significant difference with normal males (p > 0.05). Except for the value of DNA damage, other values of sperm motility, related enzymes activities and fertilization rate of sex-reversed female sperm declined after a process of cryopreservation (p < 0.05). But the frozen sperm can still get nearly 60% of the fertilization rate. This study identified the physiological and biochemical characteristics of the fresh and cryopreserved sperm from sex-reversed female mandarin fish, and the sex-reversed female spermatozoa can be used for actual production.

Study of enzyme activities and protein content of beluga (Huso huso) semen before and after cryopreservation

Knowledge gained regarding the biochemical processes that occur during sperm collection, processing and freezing-thawing might improve current sperm cryopreservation techniques. In our present study, we determined the effect of cryopreservation on the total protein concentration (TP) and the activities of certain enzymes in semen samples from the beluga (Huso huso). The TP content of the seminal plasma of fresh semen was 0.47 ± 0.026 g/l, and the TP after cryopreservation was 1.86 ± 0.6 g/l. The activities of acid phosphatase (0.82 ± 0.042 U/l), lactate dehydrogenase (234.4 ± 19.4 U/l), arylsulfatase (143.1 ± 32.5 U/l) and β-N-acetylglucosaminidase (58.39 ± 4.14 U/l) in the seminal plasma of fresh semen were significantly lower than those in the supernatant of frozen-thawed semen samples (7.43 ± 0.64, 3224.6 ± 167.2, 422.6 ± 21.3 and 90.2 ± 5.37 U/l respectively). These parameters may be useful as biomarkers for estimating damage to the cell membrane of spermatozoa caused by freezing-thawing.

The antagonism of aluminum against fluoride-induced oxidative stress and c-Fos overexpression in rat testes

Sodium fluoride (NaF) has been found to interfere with the reproductive system of animals. However, the cellular mechanisms underlying the reproductive toxicity of fluoride are unclear. The present study aims to define a possible mechanism of NaF-induced reproductive toxicity with respect to mineral, oxidative stress and c-Fos expression and the role of aluminum (Al) in intervening the toxic effect of NaF on rat testes. Fifty-six male Wistar rats were treated with normal saline, 1.0, 2.0, and 3.0 mg NaF/kg body weight (bw)/day, and each NaF concentration plus Al ion (0.1 mg Al(3+)/kg bw/day). After 90 days, no significant changes in the contents of Fe and Cu were observed in any of the NaF-treated groups compared with those of the control group. There were, however, significant decreases in the contents of Ca in the 1.0 mg NaF group, Zn in all NaF-treated groups and Mg in the 3.0 mg NaF group. The levels of malondialdehyde (MDA) in the 1.0 mg NaF group and hydrogen peroxide (H2O2) in the 2.0 mg NaF group significantly increased, whereas the activity of nitric oxide synthase (NOS) significantly decreased in the 1.0 mg NaF group. Meanwhile, the protein expression of c-Fos increased significantly in the 1.0 and 2.0 mg NaF groups compared with the control group. Conversely, these changes were partially attenuated in rats simultaneously administered Al. The present study suggested that NaF could decrease the contents of Ca, Fe and Mg and enhance oxidative stress leading to c-Fos overexpression, and some deleterious effects were more prominent at lower NaF intake. Furthermore, Al within the research concentration could minimize reproductive toxicity caused by fluoride.

Involvement of oxidative stress in municipal landfill leachate-induced toxicity in boar sperm

Exposure to leachates generated from an improperly managed hazardous waste dump sites is detrimental to human health and the ecosystem. The present study investigated the effect of Olushosun municipal landfill leachate (OMLL) on sperm characteristics and antioxidant systems in boar sperm cells. The sperm cells were incubated with the leachate at final concentrations of 0, 1, 2, 4 and 8% for 3h at 37 °C. Sperm characteristics were monitored hourly during the incubation period whereas aminotransferases activities and oxidative stress indices were determined after the incubation period. Results revealed a time- and dose-dependent decline in sperm progressive motility from 1h post-treatment with 2, 4 and 8% OMLL whereas decreased sperm viability with elevated abnormalities were observed from 2 h post-treatment with 4 and 8% OMLL when compared with control. Exposure to OMLL caused a significant increase in aminotransferases, catalase and glutathione-S-transferase activities whereas it markedly decreased superoxide dismutase and glutathione peroxidase activities without affecting glutathione level in the treated sperm cells. Co-incubation of sperm with OMLL increased the levels of hydrogen peroxide and malondialdehyde levels. In conclusion, OMLL elicited spermatotoxicity via induction of oxidative stress possibly generated through an enhanced intracellular reactive oxygen species.

Sperm proteins in teleostean and chondrostean (sturgeon) fishes

Sperm proteins in the seminal plasma and spermatozoa of teleostean and chondrostean have evolved adaptations due to the changes in the reproductive environment. Analysis of the composition and functions of these proteins provides new insights into sperm motility and fertilising abilities, thereby creating possibilities for improving artificial reproduction and germplasm resource conservation technologies (e.g. cryopreservation). Seminal plasma proteins are involved in the protection of spermatozoa during storage in the reproductive system, whereas all spermatozoa proteins contribute to the swimming and fertilising abilities of sperm. Compared to mammalian species, little data are available on fish sperm proteins and their functions. We review here the current state of the art in this field and focus on relevant subjects that require attention. Future research should concentrate on protein functions and their mode of action in fish species, especially on the role of spermatozoa surface proteins during fertilisation and on a description of sturgeon sperm proteins.

Isolation and unique composition of purified head plasma membrane from rooster sperm

The structure, composition, and function of membranes from organelles of mammalian spermatozoa differ from each other and from the sperm's plasma membrane. Avian sperm studies have suffered from the lack of a technique to isolate these various membranes, which the current study now provides. Nitrogen cavitation and differential centrifugation separated head plasma membranes (HPM) of rooster sperm from sperm debris, acrosomal membranes, and mitochondrial membranes and characterized these membranes enzymatically and microscopically. The HPM was enriched in acid phosphatase (marker enzyme for HPM; 1,814.81 +/- 470.43 micromol phosphate released/microg protein vs. 868.53 +/- 75.55 for whole semen; a 202.5 +/- 37.8% enrichment, mean +/- SE, P < 0.001), with less (P < 0.001) mitochondrial and acrosomal enzyme activity. The mitochondrial fraction had 515.1 +/- 167.6% more succinate dehydrogenase activity (marker for mitochondria, P < 0.001) and the acrosomal fraction had 315.4 +/- 61.2% more acetylglucosaminidase activity (marker for acrosome, P < 0.0001) than whole semen. Thin layer and gas chromatography showed that HPM lipids had more (P < 0.05) sphingomyelin and phosphatidylserine, and less phosphatidylcholine and phosphatidylethanolamine than did the sperm body membranes (SBM). Overall, HPM had less polyunsaturated fatty acids than SBM (36.8 +/- 3.4 vs. 44.5 +/- 1.7% of total phospholipids, P < 0.05). HPM had slightly more n3 (3.2 +/- 0.5 vs. 1.3 +/- 0.2%, P < 0.01) but much less n6 (33.6 +/- 3.3 vs. 43.3 +/- 1.9%, P < 0.01), specifically less C22:4n6. Future study of avian sperm will be able to reliably characterize the structure-function relationships of specific sperm membranes.

Effect of extender composition and equilibration time on fertilization ability and enzymatic activity of rainbow trout cryopreserved spermatozoa

The effects of extender composition and equilibration time on fertilizing ability of cryopreserved spermatozoa from rainbow trout, Oncorhynchus mykiss, were investigated. In addition, enzyme activity in supernatants from thawed sperm was assessed. The use of the two extenders: Erdahl & Graham's + 10% DMA (dimethyl acetamide) + 10% egg yolk and 0.3 M glucose + 10% DMA yielded the highest post-thaw fertilization rates. We observed interactions between extender constituents and the equilibration of diluted semen. This indicates a multifactorial effect of the extender constituents on spermatozoal resistance against injuries. The 10-min equilibration of spermatozoa in extender before freezing generally lowered the fertilization ability of spermatozoa, except for DMA-based extenders. The addition of egg yolk to the extender was generally beneficial, especially in DMA- and DMSO-based extenders. The use of low-density lipoprotein fraction showed no advantage to full-yolk or free-of-yolk extenders. Aspartate aminotransferase and lactate dehydrogenase leakage from damaged spermatozoa correlated negatively with the ability of cryopreserved spermatozoa to fertilize eggs. Each factor tested, when analyzed separately, did not give general information about its effect on the fertilization ability of cryopreserved sperm. The multifactorial analysis of the important factors in cryopreservation of trout spermatozoa showed their cumulative effect. This is the most likely reason for divergent information reported elsewhere on the effect of various factors in the cryopreservation of rainbow trout spermatozoa.

Characteristics of sperm acrosin-like activity of paddlefish (Polyodon spathula Walbaum)

Spermatozoa of paddlefish and sturgeon fishes (Acipenseriformes), unlike teleost fish, have an acrosome. The objectives of this study were to characterize acrosin-like activity of cryopreserved sperm of paddlefish (Polyodon spathula) and to test and compare stability of paddlefish acrosin-like activity with that of lake sturgeon and bull spermatozoa. Mean acrosin-like activity of cryopreserved paddlefish sperm was 0.372 +/- 0.067 microU/10(6) spermatozoa. This activity was 79% higher in the whole semen than in spermatozoa. Highest activity was recorded at pH 8.0 and 8.5. Triton X-100, zinc ions and 4'-acetamidophenyl 4-guanidinobenzoate (AGB) inhibited the activity. Amidase activity was also inhibited by N-alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK). TLCK at concentrations of 0.1 and 1.0 mM gave a significant decrease in activity of 19 and 61%, respectively. However, TPCK significantly inhibited amidase activity (by 19%) only at concentration 1.0 mM. After acidification and 60 min incubation at 4 degrees C of sperm suspensions only 4% of the activity was retained. A similar phenomenon was observed in the case of lake sturgeon but not bull sperm. These results suggest that trypsin-like activity of Acipenserid fish resembles rather fish trypsin that mammalian one. In frozen-thawed paddlefish sperm a minute chymotrypsin-like activity was also indicated, when GPNA was used as substrate. This activity amounted to 0.0415 +/- 0.0138 microU/10(6) spermatozoa and was 18% of total amidase activity. This suggests that chymotrypsin-like activity may also be present in paddlefish spermatozoa.