The effect of extenders, cryoprotectants and cryopreservation methods on common carp (Cyprinus carpio) sperm

Short-Term Low-Temperature Storage and Cryopreservation of Qihe Crucian Carp (Carassius auratus) Sperm

Qihe crucian carp Carassius auratus is one of the major economic aquacultural fish species in China. Due to environmental degradation and the impact of the reproduction mode of gynogenesis, the wild population of Qihe crucian carp exhibits an extremely low proportion of males. Therefore, it is imperative to develop the sperm preservation technology for Qihe crucian carp. In this study, the indicators, including sperm motility, sperm movement time, and sperm lifetime, were applied to evaluate the preservation effects of various extenders, cryoprotectant types and concentrations, and preservation manners, thus establishing the techniques of sperm short-term storage and cryopreservation for Qihe crucian carp. The results showed that HBSS was the most suitable extender solution, in which the sperm motility reached 93.00%. Under room temperature (26 °C), the sperm motility showed no significant differences across six different cryopreservation solutions. Under low temperature (4 °C), a 15% MeOH solution presented the most effective preservation effects of sperm in the short-term low-temperature storage. For cryopreservation in liquid nitrogen, the sperm activity in 20% DMSO was significantly higher than that in other solutions, representing the optimal cryopreservation solution. Furthermore, it was found that the sperm activity preserved by liquid nitrogen was significantly higher than that preserved by the ultra-freezer (-80 °C), indicating that the ultra-freezer cannot substitute for liquid nitrogen in cryopreservation. This is the first study to investigate the preservation of Qihe crucian carp sperm, providing valuable technical support for both genetic resource conservation and artificial breeding programs.

Hormone-Driven Temperature Optimization for Elevated Reproduction in Goldfish (Carassius auratus) under Laboratory Conditions

This study investigates the efficacy of hormone-induced artificial reproduction in goldfish (Carassius auratus) under controlled temperatures. Ovaprim injections significantly enhanced ovulation and sperm production compared to controls. Medium temperature (22 °C) produced the highest ovulation rates, fastest ovulation timing, and optimal sperm quality (motility and morphology) compared to high (28 °C) and low (16 °C) temperature groups. The low-temperature group exhibited reduced sperm motility duration and higher rates of sperm and larvae damage. The sperm volume of the high-temperature group was higher, but their post-injection survival rates were lower. Furthermore, the lowest spawning rate and low egg quality were noted in the high temperature. Cryopreservation using extender E4 (15% DMSO) exhibited superior post-thaw sperm motility and achieved higher fertilization rates. Fertilization rates, embryo development, and larval survival were all highest at the medium temperature. Larvae hatched from fresh sperm at medium temperature exhibited faster growth and fewer deformities. These findings suggest that hormone stimulation coupled with a medium temperature regimen is critical for successful artificial reproduction in goldfish. Cryopreservation with extender E4 holds promise for sperm banking; however, further optimization is necessary to improve fertilization success with thawed sperm. Future research could explore the influence of temperature on sperm physiology and refine cryopreservation protocols to enhance fertilization rates.

Applying a heat transfer mathematical model for the cryopreservation of rainbow trout (Oncorhynchus mykiss) sperm: How straw location over liquid nitrogen level affects freezing rate and fertilization yield

Cryopreservation of rainbow trout semen under field conditions was analyzed. Straw location over liquid nitrogen level is a crucial variable that affects freezing rate and fertilization yield due to changes in nitrogen vapor external temperature. The objectives were: to analyze cryopreservation protocols by experimentally measuring the cooling rates and fertilization yield of 0.5 ml plastic straws located in nitrogen vapor at different heights corresponding to different external temperatures; to numerically simulate the freezing process, by solving the heat transfer partial differential equations with the corresponding thermo-physical properties of the biological system and the plastic straw; to evaluate and analyze the surface heat transfer coefficient (h) during the freezing process of the straws; to introduce a new variable, the characteristic freezing time (tc), that enables comparison between protocols; this variable was defined as the elapsed period between the initial freezing temperature and a final reference temperature of -40 °C (temperature in which more than 80 % of the water is in a frozen state). The mathematical model predicted the temperature distribution inside the straw, showing a low effect of straw plastic materials (polyethylene-terephthalate glycol, polyvinyl-chloride, and polypropylene) on freezing rates. The average h value obtained from numerical simulations was 25.5 W/m2 K, close to that obtained from the analytical Nusselt correlation for natural convection. An improvement on fertilization trials was observed when the average external nitrogen temperature was -129.6 °C (temperature range: -94 to -171 °C) with an average tc of 56.8 s (ranging between 47 and 72 s). These results corresponded to a height above the level of liquid nitrogen of 2 cm. Comparison with literature reported data showed satisfactory results. Applying mathematical models in the cryobiology field achieved results that are relevant for cryopreservation activities.

Exploring pathways toward open-hardware ecosystems to safeguard genetic resources for biomedical research communities using aquatic model species

Development of reliable germplasm repositories is critical for preservation of genetic resources of aquatic species, which are widely utilized to support biomedical innovation by providing a foundational source for naturally occurring variation and development of new variants through genetic manipulations. A significant barrier in repository development is the lack of cryopreservation capability and reproducibility across the research community, posing great risks of losing advances developed from billions of dollars of research investment. The emergence of open scientific hardware has fueled a new movement across biomedical research communities. With the increasing accessibility of consumer-level fabrication technologies, such as three-dimensional printers, open hardware devices can be custom designed, and design files distributed to community members for enhancing rigor, reproducibility, and standardization. The overall goal of this review is to explore pathways to create open-hardware ecosystems among the communities using aquatic model resources for biomedical research. To gain feedback and insights from community members, an interactive workshop focusing on open-hardware applications in germplasm repository development was held at the 2022 Aquatic Models for Human Disease Conference, Woods Hole, Massachusetts. This work integrates conceptual strategies with practical insights derived from workshop interactions using examples of germplasm repository development. These insights can be generalized for establishment of open-hardware ecosystems for a broad biomedical research community. The specific objectives were to: (1) introduce an open-hardware ecosystem concept to support biomedical research; (2) explore pathways toward open-hardware ecosystems through four major areas, and (3) identify opportunities and future directions.

A brief review of the methodology and cryoprotectants in selected fish and mammalian species

Cryopreservation is a valuable technique used to assist in the genetic improvement of cultured stocks and provide a continuous supply of good-quality semen for artificial insemination. Conserving semen by cryopreservation serves several purposes (e.g. artificial reproductive technologies and species conservation) and is also used in the clinical treatment of human infertility. However, the lifespan of cryopreserved semen is influenced by a range of factors, including storage temperature, cooling rate, chemical composition of the extender, the concentration of cryoprotectant, reactive oxygen species, seminal plasma composition and hygienic control. The choice of cryoprotectant is a vital factor underlying the success of animal semen cryopreservation. In this regard, extensive research has been carried out on various cryoprotectants, such as egg yolk, dimethyl sulfoxide, methanol, ethylene glycol and dimethylacetamide. Recent studies have also described the use of a range of new cryoprotectants for cryopreservation, including compounds of plant origin (soy), amino acids, antifreeze proteins, carbohydrates and cyclodextrins. Moreover, semen cryopreservation and storage require the use of liquid nitrogen or ultralow refrigeration methods for both long- and short-term storage. This review summarizes the general methods used for freezing semen and discusses the use of traditional and newly emerging cryoprotectants (permeable and non-permeable) for the cryopreservation of semen in selected fish and mammalian species.

Cryopreservation of black seabream (Acanthopagrus schlegelii) sperm

In recent years, biotechnology has had a significant impact on the aquaculture industry, particularly in the field of breeding. Molecular selection breeding has emerged as a novel approach to breeding. Reducing the cost of genetic information for individuals with desirable traits after breeding has become an important research direction. Cryopreservation technology allows bypassing time and space constraints in genetic breeding, simplifying broodstock management. This study presents a detailed cryopreservation method for black seabream sperm, evaluating extender type, glucose concentration, cryoprotectant type and concentration, sperm-dilution ratio, and cooling protocols. Sperm motility parameters were analyzed using computer-assisted sperm analysis (CASA) before and after two days of freezing. This involved using an RS solution with a glucose concentration of 15 g/L and adding a 5% final concentration of EG as the sperm cryoprotectant. After mixing the sperm and solution at a ratio of 1:2, we subjected it to 5 min fumigation at 5 cm above the liquid nitrogen surface before plunging it into the nitrogen. Sperm motility reached 85.46 ± 7.32% after two days. Various enzymatic activities showed changes over 20 days post-cryopreservation. This improved cryopreservation protocol for black seabream sperm is beneficial for genetic breeding and reproduction and provides reference for studying the cryodamage mechanisms of black seabream sperm.

Effect of cryopreservation on post-thaw motility and viability of Grey mullet, Mugil cephalus sperm (Linnaeus, 1758)

In this study, we optimized a simple method of cryopreservation for Mugil cephalus sperm based on post-thaw motility and viability. A series of experiments were conducted by changing the extender, cryoprotectant and freezing height above the liquid nitrogen (LN) surface. First, we carried out the cryopreservation using the extender V2E and cryoprotective agents (CPAs) namely, propylene glycol (PG), methanol (MeOH), glycerol (GLY), ethylene glycol (EG), dimethylsulfoxide (Me2SO) and dimethylacetamide (DMA) at a final concentration of 5% and 10%. We found that 10% of GLY, EG and Me2SO were more suitable compared to other CPAs. Then, different freezing heights (6, 8, 10 and 12 cm) above the LN surface were experimented with extender V2E and optimized CPAs. Then, 0.3 M of glucose, sucrose and trehalose were tested as extender along with optimized CPAs and freezing height. Additionally, the effect of fast-rate freezing and storage days (7, 30 and 180) on post-thaw sperm quality was documented using the factors optimized in earlier experiments. For all experiments, the fresh sperm was diluted at a ratio of 1:1 with cryomedium (CPA + extender), loaded into cryovials (2.0 mL) and frozen. The cryopreserved sperm was thawed at 30 °C for 90-120 s and their quality was evaluated. Among the experimented factors, sperm diluted in cryomedium (0.3 M glucose + 10% EG) and frozen at 4 cm above the LN surface registered significantly (P < 0.05) highest post-thaw motility (73 ± 2%) and (71 ± 1%) viability. Fast-rate freezing has resulted in lower (about 30%) post-thaw motility and viability of sperm. The storage days (7, 30 and 180) did not have a significant effect on post-thaw sperm quality. Overall results show that using the factors optimized through this study, high-quality sperm can be obtained after cryopreservation.

The emerging role of open technologies for community-based improvement of cryopreservation and quality management for repository development in aquatic species

Genetic resources of aquatic species are of tremendous value, but worldwide these are maintained almost exclusively as live populations. This is extremely expensive and insecure, and largely results from a pervasive lack of production capability, quality management, and reproducibility in cryopreservation that are barriers in development of germplasm repositories. Community-based technology approaches are emerging that can stimulate research previously limited by a lack of affordable, customizable equipment. Open-access technologies can provide for custom design and fabrication not available through traditional manufacturing. This can assist repository development with robust sample production methods and strong quality management, and can greatly improve reproducibility and standardization. Open technologies can support establishment of new communities of users, makers, and developers that collectively strive to develop open hardware in a distributed (i.e., non-centralized) fashion that can yield aggregate throughput. This occurs through use of consumer-level tools, supplies, software, and equipment, free exchange of designs and modifications, and a shared sense of mission. For cryopreservation and repository development, we have identified 14 categories of open hardware for a processing pathway, and six categories for a quality management pathway. Open hardware offers economic incentives to develop repositories for aquatic species, something that has not occurred despite 70 years of research largely focused on protocol development rather than practical applications. Advanced development of custom scientific hardware enhancing open technologies will be facilitated by interdisciplinary collaboration across biological and engineering fields. This manuscript is a contribution to the Special Issue in memory of Dr. Duane Garner, a leader in the sperm biology.

Cryopreservation and Its Application in Aquaculture

Aquaculture is the major aquatic animal production segment. Problems like inbreeding depression, genetic drift, introgressive hybridization, etc. have been influencing the production of quality seeds negatively. Cryopreservation serves as a way-out for these problems and a possible answer to produce quality seeds and genetically improved varieties. It has been considered as a major strategy for conservation of fish genetic resources. Cryopreservation of fish gametes has been in vogue since 1953 and the technology is well studied and validated for many species. So far the milt of 200 fish species has been cryopreserved successfully. In this chapter, the importance of aquaculture in overcoming malnutrition, genetic issues affecting quality seed production, cryopreservation protocol employed for various fish species, problems faced in cryopreserving fish eggs and embryos and future of cryopreservation in aquaculture have been discussed.

Development of an open hardware 3-D printed conveyor device for continuous cryopreservation of non-batched samples

A great challenge among communities participating in germplasm repository development is to obtain suitable cryopreservation equipment and devices. Commercial programmable freezers are costly and thus unaffordable to many users. Self-made devices have substantial variability among users, resulting in few opportunities for standardization across communities. The development of open hardware with the increasing accessibility of three-dimensional (3-D) printing offers rapid prototyping and easy fabrication of devices by users around the world at low cost. The present study explored the feasibility of developing operational prototypes of 3-D printed motorized cryopreservation devices for continuous freezing of non-batched samples. A controlled cooling conveyor device (CCCD) was designed and fabricated to cryopreserve sperm samples in straws that were loaded onto chain links suspended over liquid nitrogen held in a Styrofoam box. Cooling rates of 5 to 34 °C/min for 0.5-ml French straws were produced by adjusting the height of conveyor chains, slopes, and liquid nitrogen mass. The plunge temperature (-47 °C to -61 °C) was controlled by adjustment of conveyor speed. The cooling curves from the CCCD were comparable to a commercial programmable freezer. There were no significant differences in post-thaw motility of sperm from ornamental (Koi) common carp (Cyprinus carpio) among samples frozen with the CCCD and those frozen with a commercial programmable freezer. The post-thaw sperm motility was consistent among samples frozen in the CCCD across a 15-min time span. The CCCD prototypes in the present study proved to be feasible and functional as low-cost, customizable, portable, and yet standardizable options for freezing of individual (non-batched) samples. Additional design alternatives are proposed to facilitate further adaptation and development by diverse user communities.

Effect of alpha-lipoic acid on oxidative stress, viability and motility in the common carp (Cyprinus carpio) spermatozoa after short-term storage and cryopreservation

As known for different metabolic functions, α-lipoic acid (ALA) has been tested for spermatozoa preservation of animals as well as of human, but not for fish spermatozoa. The present study determined the effects of ALA on short and long-term (cryopreservation) preservation of common carp (Cyprinus carpio) spermatozoa, for the first time. For that, spermatozoa were diluted in extenders containing 0 (control), 0.025, 0.05, 0.1, 0.5, 1, 2, 5, and 10 mM of ALA concentrations in both short-term preservation and cryopreservation. Spermatozoa motility parameters by computer-assisted semen analysis, viability, lipid peroxidation and catalase activity in spermatozoa were conducted in both 2nd and 120th hours of short-term storage and post-thaw samples. Higher percentages of total spermatozoa motility (80 ± 3) and viability (87 ± 3) were observed in 0.5 mM ALA group after 120 h of incubation. In post-thaw samples, higher percentages of these parameters were in 1 mM ALA group (74 ± 3 and 83 ± 2, respectively). Moreover, the results have shown that the addition of ALA until concentrations of 2 mM improved especially spermatozoa curvilinear velocity, maintained viability, and suppressed excessive lipid peroxidation during the preservations. In conclusion, the additions of 0.5 mM ALA for short-term preservation and 1 mM ALA for cryopreservation were the optimal concentrations, and shown the protective effects on common carp spermatozoa, when considering all measured parameters together.

Criopreservación de semen de bagre rayado Pseudoplatystoma magdaleniatum con tres diferentes crioprotectores

El objetivo fue criopreservar semen de bagre rayado Pseudoplatystoma magdaleniatum con tres crioprotectores internos diferentes: dimetilsulfóxido (DMSO), dimetilacatamida (DMA) y etilenglicol (ETG) a dos porcentajes de inclusiones (5 y 10%), combinados con glucosa 6%, leche en polvo descremada 3% y vitamina E (0,4%). Cinco machos en fase de espermiación fueron inducidos con 0,4 ml de Ovaprim®/Kg. El semen fue diluido en la solución crioprotectora (1:3) en tubos de 2,5 ml, congelado en vapores de nitrógeno y descongelado a 35°C durante 90 segundos. El análisis estadístico incluyó un diseño factorial 3x2 y semen fresco (SF) como tratamiento testigo. En semen fresco, precongelado y descongelado se evaluó la movilidad total (Mt), tipos de movilidad, progresividad total y velocidades espermáticas con la ayuda de Sperm Class Analyzer SCA®. El SF registró volumen de 6,1±4,3 ml, Mt de 72,6±17,1%, activación de 31,2±2,1 segundos y concentración espermática de 54,7±22,9 millones/μl. En semen precongelado, el crioprotector (p<0,05) y porcentaje de inclusión (p<0,01), pero no su interacción, tuvieron un efecto significativo en la Mt, velocidad curvilínea (VCL) y velocidad lineal (VSL); mientras que en semen descongelado sólo la interacción de los factores (p<0,05) fue significativa en Mt, porcentajes de espermatozoide estáticos y VCL. La Mt cayó entre 36-67% en semen precongelado y entre 74-86% en semen descongelado con relación a SF. Los resultados sugieren que DMSO, DMA y ETG incluidos a 5 o 10%, combinados con leche en polvo 3%, glucosa 6% y vitamina E 0,4% son alternativas viables de criopreservación del semen de bagre rayado.

Seminal plasma transferrin effects on cryopreserved common carp Cyprinus carpio sperm and comparison with bovine serum albumin and antifreeze proteins

In the current study, there was evaluation of the cryopreservation effectiveness of common carp Cyprinus carpio sperm when cryopreservation medium was supplemented with proteins. Semen was diluted with Kurokura's extender composing 180 mM NaCl, 2.68 mM KCl, 1.36 mM CaCl₂, 2.38 mM NaHCO₃, and 10% dimethylsulfoxide (DMSO). Cryopreservation medium was supplemented with purified seminal plasma transferrin (Tf), bovine serum albumin (BSA) or antifreeze protein (AFP) Types I and III. Concentration of proteins evaluated was 0.1 μg/ml, 1 μg/ml, and 10 μg/ml. Motility and curvilinear velocity of spermatozoa was evaluated by the Computer Assisted Semen Analyzer (CASA). The percent of motile cells and spermatozoa curvilinear velocity of frozen-thawed sperm with supplementation of Tf and AFP III at all concentrations were greater compared to samples with no added proteins. The protective effect of BSA and AFP I was less and dose-dependent. Thus, it is concluded that incorporation of Tf in the extender before freezing improves crypreservation of common carp spermatozoa whereas supplementation with AFP III in greater concentrations was more effective.

The comparison of two different extenders for the improvement of large-scale sperm cryopreservation in common carp (Cyprinus carpio)

In our study, a traditionally used (Grayling, already used in cyprinid species) and a newly tested (Pike) extender was tested to avoid sperm agglutination phenomenon following thawing during carp sperm cryopreservation. A large-scale (elevated volume of sperm) freezing method in a controlled-rate freezer using 5 ml straw and 10 ml cryotube was also systematically established. In all experiments, the sperm cryopreserved in using Grayling extender (except only one sample) showed an agglutination phenomenon (damaged and intact cells adhered to each other) after thawing where Pike extender resulted the regular cell suspension. No significant difference was observed between the two cryopreserved groups (Pike and Grayling extender) in all motility parameters using the 0.5 ml straw and the polystyrene box. Similarly, motility parameters did not show a significant difference in the two frozen groups with the 5 ml straw, also in the polystyrene box. A significantly higher progressive motility (pMOT, Grayling: 54% ± 8%, Pike: 37% ± 5%), straight line velocity (VSL, Grayling: 50 ± 5 µm/s, Pike: 39 ± 4 µm/s) and beat cross frequency (BCF, Grayling: 20 ± 1 Hz, Pike: 17 ± 1 Hz) was observed in the case of the grayling extender by the 5 ml straw cryopreserved in a controlled-rate freezer (CRF) compare to the pike extender. A significantly higher VSL (Grayling: 45 ± 3 µm/s, Pike: 38 ± 4 µm/s) was observed by the grayling extender using the 10 ml cryotube than with the pike extender. Despite the randomly occurring differences in a few parameters, our new controlled freezing method using the newly tested Pike extender, the 5 ml straw or the 10 ml cryotube can be a good solution for the preservation of elevated volume of carp sperm.

Efeito de vitaminas adicionadas ao diluente ACP-104 sobre a qualidade do sêmen criopreservado de carpa comum - Cyprinus carpio )

RESUMO O objetivo da presente pesquisa foi alcançado com a divisão da pesquisa em dois experimentos: (1) aperfeiçoar o protocolo de congelação utilizando água de coco em pó (ACP-104) como diluente para a criopreservação seminal de carpa comum; (2) avaliar o efeito da suplementação das vitaminas C (ácido ascórbico) ou E (α-tocoferol) sobre os melhores diluidores testados no experimento 1 na qualidade do sêmen pós-descongelado da espécie. Para o experimento 1, foram formados oito pools de sêmen, provenientes de 14 machos selecionados. As amostras seminais coletadas foram avaliadas quanto à motilidade total, à velocidade, ao percentual de espermatozoides normais e à vitalidade espermática antes e depois da criopreservação seminal. Esta foi realizada em meio ACP-104 acrescido de dimetilsulfóxido (DMSO), ou etilenoglicol (EG), ou glicerol, ou metanol, todos à concentração de 10%, diluídos em 1:3 (sêmen:diluidor). As amostras foram, então, congeladas em vapor de nitrogênio líquido em dry shipper e estocadas em nitrogênio líquido (-196°C). Para o experimento 2, foram formados oito pools provenientes da coleta de sêmen de 15 machos. As amostras seminais foram avaliadas seguindo as mesmas análises do experimento 1, acrescentando-se a duração da motilidade total. A criopreservação seminal utilizou-se do meio ACP-104 acrescido de DMSO ou EG, suplementado ou não com vitamina C ou E. Os melhores resultados encontrados no experimento 1 foram obtidos com o DMSO e o EG. Estes não diferiram significativamente entre si para a motilidade total (24% e 28%; P>0,05) e a normalidade espermática (32% e 26%; P>0,05), respectivamente. Para o experimento 2, o EG suplementado com vitamina E produziu significativamente resultados superiores de motilidade total, normalidade espermática e duração da motilidade em relação ao DMSO, concluindo-se que o EG deve ser, portanto, o crioprotetor de escolha a ser utilizado com o ACP-104 suplementado ou não com vitamina E.

Crioconservación de semen de dorada Brycon moorei con dimetilsulfóxido

El objetivo fue evaluar la calidad del semen descongelado de dorada Brycon moorei crioconservado con dimetilsulfóxido (DMSO) a tres porcentajes de inclusión. El semen se obtuvo de nueve machos mantenidos en cautiverio en la Estación Piscícola Repelón (Atlántico, Col), inducidos con extracto pituitario de carpa (4,5 mg/kg). El semen fue diluido en proporción 1:3 con un diluyente compuesto de DMSO a tres porcentajes 5%, 10% y 15%; glucosa al 6% y yema de huevo al 12%; empacado en macrotubos de 2,5 ml, congelados en vapores de nitrógeno y después de tres meses descongelados a 35°C durante 90 s. Semen fresco fue considerando como tratamiento control. En semen descongelado se evaluó movilidad total, tipos de movilidades, progresividad, velocidades y concentración espermática con el programa Sperm Class Analyzer SCA®; adicionalmente en semen fresco se determinó volumen, color y tiempo de activación. El semen fresco presentó movilidad mayor a 80% y tiempo de activación entre 28,5 y 41 s; mientras que, la concentración espermática osciló entre 10188,1 y 14590,2 millones/ml. La movilidad total del semen descongelado fue mayor cuando DMSO se incluyó a 5% (40,1±5,0%) o 10% (43,3±8,7%) (p>0,05); pero a 15% registró la menor movilidad (30,6±7,9%) y el mayor porcentaje de espermatozoides inmóviles (69.4±7.9%) (p<0,05); lo cual sugiere que inclusiones de DMSO por encima de 10% ocasionan mayores daños al espermatozoide de dorada. Los resultados permiten concluir que DMSO debe ser incluido entre 5 y 10%, junto con glucosa al 6% y yema de huevo al 12% para crioconservar semen de dorada.

Improvement of common carp (Cyprinus carpio) sperm cryopreservation using a programable freezer

The applicability of a programmable freezer for the increased-scale cryopreservation of common carp sperm was investigated. The effect of different equilibration times, cryopreservation methods, extenders, dilution ratios, activating solutions on the post-thaw motility of common carp sperm was investigated. The suitable post-thaw storage time-interval as well as fertilizing capacity of cryopreserved sperm was also examined. The motility, curvilinear velocity (VCL) and straightness (STR) values did not decrease significantly during 60min of equilibration neither in equilibrated nor thawed groups. Motility parameters of thawed sperm were similar using a conventional cryopreservation technique using a polystyrene box [motility (33%), VCL (47μm/s) and STR (88%)] and a programmable freezer: [motility (32%), VCL (54μm/s) and STR (89%)]. The highest motility and VCL was measured with a sugar based extender (grayling extender) at a ratio 1:9 (motility: 52%, VCL: 76μm/s) and 1:20 (motility: 49%, VCL: 76μm/s). The activating solution for cyprinids (ASC) could prolong sperm movement up for 2min. A storage time of six hours following thawing did not have a significant effect on the motility parameters of thawed carp sperm. Agglutination was observed during cryopreservation of an elevated volume of sperm whereas motility 47%, VCL 62μm/s and STR 91% were measured after thawing. Fertilization rate with thawed sperm (32%) was significantly lower compared to the control group (73%). According to our results, the developed method using a programmable freezer is suitable for the cryopreservation of elevated number of straws. However, carp sperm agglutination during freezing may have a negative effect on the fertilizing capacity.

The role of amides in seminal cryopreservation of wild silverside, Odontesthes bonariensis

Amides were tested as internal cryoprotectants for the preservation of wild silverside (Odontesthes bonariensis) sperm. The semen was diluted in modified Mounib's medium and cryopreserved by adding 2, 5, 8 or 11% of dimethyl acetamide (DMA), dimethyl formamide (DMF) or methyl formamide (MF). Dimethyl sulfoxide (DMSO) at a concentration of 10% diluted in modified Mounib's medium was used as a control. The rate motility (17.7 ± 1.9%) and time motility (143.2 ± 9.7 s) (P < 0.05) of the sperm were higher with 2% DMF when compared with the other treatments. Despite the better motility results obtained with 2% DMF, the solution was not able to maintain cellular structure integrity of the cryopreserved sperm. The 10% DMSO and 8% MF treatment allowed for completeness of the plasma membrane (34.8% and 29%), functional mitochondria (19.8% and 16.2%) and plasma membrane fluidity (39.4% and 46.4%); furthermore, rate motility (11.8% and 10%) and time motility (81.4 s and 71.8 s) of the sperm were found to be at suitable levels when compared with 2% DMF. Thus, our evaluation suggests that 10% DMSO and 8% MF provide better cryopreservation of O. bonariensis sperm cells.

Cinética e morfologia de espermatozoides de carpa comum criopreservados em água de coco em pó ACP-104

RESUMOO objetivo deste estudo foi avaliar o efeito de diferentes taxas de diluição seminal sobre a motilidade, velocidade e presença de anormalidades espermáticas no sêmen descongelado de carpa comum (Cyprinus carpio). Utilizaram-se 20 machos sexualmente maduros, pertencentes ao Departamento Nacional de Obras Contra as Secas (DNOCS). A partir do sêmen coletado, foi formado um total de nove pools. O sêmen de cada pool foi avaliado quanto à motilidade, velocidade e morfologia espermática antes e depois da criopreservação. A criopreservação seminal foi realizada em meio ACP-104 + DMSO 10% diluído em 1:1 ou 1:3 (sêmen:diluidor). As amostras foram envasadas em palhetas de 0,25mL, congeladas em vapor de nitrogênio líquido (caixa de poliestireno) e estocadas em nitrogênio líquido (-196 °C). Não houve diferença significativa (P>0,05) entre as taxas de diluições sobre os parâmetros cinéticos e morfológicos de sêmen descongelado de carpa comum. Entretanto, esses parâmetros apresentaram diferença significativa (P<0,05) em relação ao sêmen fresco (controle). Baixos valores de velocidade foram registrados no sêmen descongelado (VCL 42,6-46,5μm/s; VSL 33,2-37,1μm/s; VAP 38,9-43,2μm/s); contudo, observaram-se motilidades acima de 59% (59,8-67,8%) e baixos índices de anormalidades espermáticas (19,3-19,5%), sugerindo que o ACP pode ser usado como um meio favorável à criopreservação do sêmen de carpa comum em qualquer uma das taxas de diluição testadas.