Morphology and ultrastructure of pink cusk-eel (Genypterus blacodes, Schneider 1801) spermatozoa by scanning and transmission electron microscopy

In this study, the morphology and ultrastructure of Genypterus blacodes spermatozoa were characterized through scanning and transmission electron microscopy. Findings revealed that the G. blacodes spermatozoa can be differentiated into three major parts: a spherical head without an acrosome (typical for externally fertilizing fish), a short mid-piece, and a long flagellum. The mean length of the spermatozoa was 57.6 ± 6.08 μm, with flagella accounting for 56.2 ± 7.2 μm. The head was 1.47 ± 0.2 μm long, and 0.89 ± 0.06 μm wide. The mid-piece had a total dimension of 0.72 ± 0.16 μm, and was 0.31 ± 0.02 μm in length and 0.6 ± 0.05 μm in width. It was located lateral to the nucleus and contained 4 or 5 spherical mitochondria. The mitochondria were separated from the axoneme by a cytoplasmic canal. The main piece of the flagellum had short irregular side-fins, and the axoneme was composed of the typical 9 + 2 microtubular doublet structure enclosed by a cell membrane. The present study reveals that G. blacodes sperm can be categorized as a primitive type. This study is the first to provide comprehensive details on the morphology and ultrastructure of spermatozoa in G. blacodes

Effect of the temperature of activation medium on fish sperm quality: Impact on fertilization in vitro in aquaculture practice

Motility is a key in spermatozoon function, determining semen quality and fertilizing capacity. Motility in fish spermatozoa occurs when they are diluted in a swimming solution, the adequacy of which is determined by factors which vary by species. Spermatozoon motility rate and velocity, as well as the duration of the motility period, are influenced by the temperature of the swimming medium. Increasing the temperature of the swimming medium has a significant negative effect on spermatozoa motility kinematics. It increases the metabolism rate of cells, causing a mismatch of energy resources and promoting changes in sperm movement. It also generates an increase in the production of reactive oxygen species (ROS) and thus oxidative stress, and moreover results in an inadequate capacity of antioxidant enzymes to protect the cell against the effects of oxidative stress induced by higher temperatures. The aim of this review is to update present knowledge about: mitochondria main source of ATP; the protein phosphorylation related to motility; epigenetic regulation of the temperature of the activation and the role of ion channels in regulation motility. These mechanisms involved in sperm motility are of vital importance in regulating fertilization, all of which can be influenced by the environment. We emphasize the importance of investigating spermatozoon mechanisms in depth, especially in the context of climate change which results in changing water temperatures. Our findings provide a better understanding of fish sperm physiology, and a biological foundation for the further development of spermatozoon motility investigation, and reproduction technologies

Morphology and ultrastructure of pink cusk-eel (Genypterus blacodes, Schneider 1801) spermatozoa by scanning and transmission electron microscopy

© 2018 Elsevier LtdIn this study, the morphology and ultrastructure of Genypterus blacodes spermatozoa were characterized through scanning and transmission electron microscopy. Findings revealed that the G. blacodes spermatozoa can be differentiated into three major parts: a spherical head without an acrosome (typical for externally fertilizing fish), a short mid-piece, and a long flagellum. The mean length of the spermatozoa was 57.6 ± 6.08 μm, with flagella accounting for 56.2 ± 7.2 μm. The head was 1.47 ± 0.2 μm long, and 0.89 ± 0.06 μm wide. The mid-piece had a total dimension of 0.72 ± 0.16 μm, and was 0.31 ± 0.02 μm in length and 0.6 ± 0.05 μm in width. It was located lateral to the nucleus and contained 4 or 5 spherical mitochondria. The mitochondria were separated from the axoneme by a cytoplasmic canal. The main piece of the flagellum had short irregular side-fins, and the axoneme was composed of the typical 9 + 2 microtubular doublet structure enclosed by a cell membrane. Th

Human sperm vitrification: A scientific report

Background The sperm vitrification developed by this group is based on the ultrarapid freezing of a vitrification solution composed of a non-permeable cryoprotectant (saccharides and protein), in which previously selected spermatozoa are resuspended, free of seminal plasma, and then plunged directly into liquid nitrogen. Compared to traditional sperm freezing, vitrification does not cause chemical or physical damage to the intracellular structures and reduces the damage to the plasma membrane because no ice crystals form, thus preserving motility and DNA integrity. Objectives This manuscript is a review of the vitrification methodology developed by the authors' research group, including studies showing the application in human reproduction therapy. Materials and methods The authors perform a review of the work initiated more than a decade ago by this research group, on the implementation of sperm vitrification, a more effective technique for cryopreservation of human spermatozoa, discussing the results obtained by other authors and the projection of this technique. Results and discussion The vitrification technique has been developed in selected spermatozoa free of seminal plasma supplemented with saccharides such as sucrose, trehalose, and dextran, together with albumin, providing a high motility rate and protective structures of the cytoskeleton. In patients, it can be used to preserve their fertility for oncological reasons, genetics, inflammatory diseases, or reproductive medicine techniques. The possibility that vitrified spermatozoa can be preserved at temperatures of -80 degrees C can simplify sample storage, optimizing the space and time as well as operator safety. Conclusion Vitrification techniques have demonstrated the preservation of selected spermatozoa without seminal plasma and with non-permeable cryoprotectants and protein. Currently, it is one of the most effective ways to maintain sperm function and has been used in in vitro fertilization or intrauterine insemination in humans, achieving healthy live births

Morphology and ultrastructure of pink cusk-eel (Genypterus blacodes, Schneider 1801) spermatozoa by scanning and transmission electron microscopy

In this study, the morphology and ultrastructure of Genypterus blacodes spermatozoa were characterized through scanning and transmission electron microscopy. Findings revealed that the G. blacodes spermatozoa can be differentiated into three major parts: a spherical head without an acrosome (typical for externally fertilizing fish), a short mid-piece, and a long flagellum. The mean length of the spermatozoa was 57.6 +/- 6.08 mu m, with flagella accounting for 56.2 +/- 7.2 mu m. The head was 1.47 +/- 0.2 mu m long, and 0.89 +/- 0.06 mu m wide. The midpiece had a total dimension of 0.72 +/- 0.16 mu m, and was 0.31 +/- 0.02 mu m in length and 0.6 +/- 0.05 mu m in width. It was located lateral to the nucleus and contained 4 or 5 spherical mitochondria. The mitochondria were separated from the axoneme by a cytoplasmic canal. The main piece of the flagellum had short irregular sidefins, and the axoneme was composed of the typical 9+2 microtubular doublet structure enclosed by a cell membrane. The present study reveals that G. blacodes sperm can be categorized as a primitive type. This study is the first to provide comprehensive details on the morphology and ultrastructure of spermatozoa in G. blacodes

Oxidative stress and use of antioxidants in fish semen cryopreservation

Reactive oxygen species (ROS) have been proposed as one of the main causes of the impairment of fish spermatozoa integrity and functionality during cryopreservation. The high content of unsaturated fatty acids in sperm cells and the low antioxidant capacity of diluted semen are key factors in making sperm cells susceptible to ROS attacks. For this reason, some recent studies have determined the antioxidant status of the seminal plasma and spermatozoa of fish species. Additionally, some studies have evaluated the effects of antioxidants on post-thaw sperm quality. Although ROS are certainly involved in sperm damage, other factors, such as ice crystal formation, seem to play a crucial role in cryodamage. This challenge has not yet been resolved because both the endogenous antioxidant capacity of the semen and its response to different supplementation practices seem to present specific inter- and intraspecies characteristics and effects. This review summarises knowledge on antioxidant defence and oxidative stress in fish semen, as well as antioxidant supplementation in cryopreservation media, in order to establish perspectives for future studies.Catholic University of Temuco [4136-2018, FEQUIP2019-INRN-03]FONDECYT/Post-doctoral grantComision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)CONICYT FONDECYT [3180765]doctorate programme in Agricultural Sciences of Catholic University of Temuco, Chileinfo:eu-repo/semantics/publishedVersio

Cryopreservation of coho salmon sperm (Oncorhynchus kisutch): Effect on sperm function, oxidative stress and fertilizing capacity

Sperm cryopreservation is an important tool for reproductive management; however, it has not been possible to perform this procedure for coho salmon. This study was designed to assess the effect of cryopreservation on sperm functional parameters, oxidative stress markers and fertilizing capacity of coho salmon. Eight extenders were tested, consisting of two intracellular cryoprotectant agents (CPA-I): dimethylsulfoxide (DMSO) at 8 and 10% and methanol (MeOH) at 9 and 12%, two extracellular cryoprotectants (CPA-E): 0.14 M trehalose and 0.18 M glucose, supplemented in all cases with 10% egg yolk and Storfish (R). Milt samples from 18 males were evaluated in three trials. In the first trial, the toxic effect of cryoprotectants on motility was evaluated after 0, 15, 30, and 60 min of equilibration time. The second trial was conducted to select the extender which produced the best post-thaw sperm motility. In both trials, sperm motility was analysed by a subjective method. In the third trial, milt samples were frozen in the three best extenders; post-thawed samples were assessed for motility by computer-assisted sperm analysis CASA, viability, superoxide anion production (O-2(center dot-)), mitochondrial membrane potential (Delta Psi m) by flow cytometry, lipid peroxidation (malondialdehyde, MDA) and fertilizing capacity were also analysed. In Trial 1, no negative effect of the extenders tested was observed on sperm motility during the different equilibration times. In Trial 2, the post-thaw sperm motility was significantly affected by CPA-I, CPA-E and their interaction, in other words, the protection capacity was dependent on the type of CPA-I and at the same time on the CPA-E. Thus, the best results were obtained with DMSO combined with glucose, with mean motility of 16.44 +/- 12.55% (8% DMSO + glucose) and 11.57 +/- 10.23% (10% DMSO + glucose). In Trial 3, all the sperm parameters were significantly affected after freezing. Mean post-thaw sperm motility varied from 20.50 +/- 15.83% to 35.80 +/- 17.64%, cell viability ranged from 56.23 +/- 11.05% to 59.42 +/- 12.00% and the Delta Psi m varied from 12.50 +/- 8.9% to 14.63 +/- 10.09%, without significant differences between the three extenders assessed in this trial. On other hand, the percentage of living spermatozoa producing O-2(center dot-) and the MDA levels increased significantly after freezing, which suggests that sperm cryodamage was caused in part by oxidative stress. The combination of either 8% or 10% DMSO with glucose yielded the best fertility rates (30.00 +/- 11.73% and 31.00 +/- 10.25% respectively). In conclusion, DMSO in combination with glucose and hen egg yolk is the most suitable extender for preserving the sperm quality and fertilizing capacity of coho salmon

Sperm morphology and ultrastructure of Patagonian blenny (Eleginops maclovinus)

In this study, the morphology and ultrastructure of Eleginops maclovinus spermatozoa were characterized through scanning and electron microscopy. Findings revealed that E. maclovinus spermatozoa can be differentiated into three major parts: a spherical head without acrosome (typical for externally fertilizing teleost), a midpiece containing 2-5 spherical mitochondria, and a long flagellum. The mean length of the spermatozoa was 40.08 +/- 2.30 mu m, with flagella accounting for 38.38 +/- 2.08 mu m. The head was 1.31 +/- 0.17 mu m long, and 1.63 +/- 0.01 mu m wide. The midpiece was 0.39 +/- 0.05 mu m in length and 0.95 +/- 0.12 mu m in width. It was located below the nucleus and contained 2 to 5 spherical mitochondria. The mitochondria were separated from the axoneme by a cytoplasmic canal. There was no evidence of the flagellum membrane forming sidefins, and the axoneme was composed of the typical 9 + 2 microtubular doublet structure enclosed by cell membrane. The present study reveals that E. maclovinus sperm can be categorized as a primitive type. This study is the first to provide comprehensive details on the ultrastructure of spermatozoa in E. maclovinus

Short-term storage sperm of coho salmon (Oncorhynchus kisutch) at 4 degrees C: Effect of sperm: Extender dilution ratios and antioxidant butyl-hydroxytoluene (BHT) on sperm function

Short-term storage of semen is a necessary key procedure in fish; it allows maximizing the use of gametes. Nevertheless, sperm quality decreases during storage has been associated with oxidative stress damage due to an increase in reactive oxygen species (ROS) during storage. This study was designed to optimize a short-term storage protocol for Coho salmon (Oncorhynchus kisutch) spermatozoa, evaluating the effect of extender dilution and the addition of butyl-hydroxytoluene (BHT) antioxidant on sperm function parameters. In the first experiment, fresh semen was diluted in Storfish (R): extender dilution (1:2 and 1:3) and a control sample undiluted and stored at 4 degrees C for 7-days. In both experiments motility (MO), viability and integrity of plasma membrane, mitochondrial membrane potential (MMP) and superoxide anion level (O-2(-)) were evaluated at 0, 3 and 7 days. Result shows that, 1:3 dilution maintained a higher sperm function for a longer period time. In the second experiment, spermatozoa were suspended in Storfish (R) (1:3) supplemented with two different concentrations of BHT (1.0 mM and 2.0 mM) and a control sample without antioxidant and stored at 4 degrees C for 7 days. The results demonstrated that, antioxidant-supplemented samples greater MO than control samples (P 75% during storage in all groups. MMP was higher in 2.0 mM BHT compared to 1.0 mM and control (P < 0.05), in addition, this concentration reduced O-2(-) level (P < 0.05). In conclusion, sperm: extender dilution 1:3 and adding of 2.0 mM BHT in sperm storage extender may enhance protection sperm function in Oncorhynchus kisutch against effects harmful of the oxidative stress during the in vitro storage