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The quality and quantity of stripped and testicular wild northern pike (Esox lucius) sperm was compared and the effectiveness of short-term storage was assessed. Stripped sperm (SS) was collected using abdominal massage. Next, the fish were decapitated and the testes were removed. Testicular sperm (TS) was collected by gently macerating the testes through double-layered gauze. The volume and number of sperm were assessed in SS and TS. Computer-assisted sperm analysis (CASA) was used to determine SS and TS motility and kinetic parameters. Undiluted samples of SS and TS were then stored short-term under refrigeration (8°C) for 72 h. A higher volume and number of sperm were noted for TS compared to SS. On the other hand, motility and kinetic parameters of SS and TS were similar immediately after collection. Seminal plasma osmotic pressure was lower in SS compared to TS. Regardless of the sperm source (SS or TS), values of sperm motility and kinetic parameters remained high during short-term storage for 24 h. However, after 48 and 72 h significant decreases in the values of MOT, curvilinear velocity (VCL, μm s -1 ), straight-linear velocity (VSL, µm s -1 ), and amplitude of lateral head displacement (ALH, µm) parameters were noted in SS compared to TS. This indicated that northern pike sperm obtained from spermatic ducts lost their biological value (fertilization capacity) much faster than that obtained from testes. This was most likely due to the presence of urine and its long-term negative impact on storage efficiency of SS compared to TS., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Sperm adhering to glass slides is one of the main problems during fish sperm motility analyses with CASA systems. To mitigate this, albumin is the supplement added most frequently to activating solutions. However, there is no data on the use of supplements other than albumin (in various concentrations) in analyses of European whitefish (Coregonus lavaretus) sperm motility. This issue was investigated in the presented research using three anti-adhesive supplements (albumin, casein, Pluronic F-127) that were added to Billard solution (BS: 20 mM Tris, 1 mM CaCl 2 , 154 mM NaCl, 30 mM glycine at pH 9.0) at different concentrations (0.0; 0.1; 0.2; 0.5; 1.0; 2.0%). It was noted that the addition of the lowest concentration (0.1%) of albumin, casein, or the pluronic to BS had a significant effect on the motility and kinetic parameters of whitefish sperm compared to pure BS. BS supplemented with 0.2-0.5% albumin was the most appropriate variant used for whitefish sperm motility activation in the present experiment. BS supplemented with the pluronic at 1.0-2.0% concentrations resulted in significantly higher values of almost all CASA parameters compared to casein at the same concentrations. Moreover, CASA parameters determined in this variant of the pluronic (1.0-2.0%) were similar to those when BS was supplemented with the same albumin concentrations. This indicated that instead of albumin, the pluronic at higher concentrations in BS might be used to analyze whitefish sperm motility., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The purpose of this study was to compare four activation solutions (AS)-Woynarovich, Lahnsteiner, Kucharczyk, and Perchec-with the addition of 0.5% bovine serum albumin (BSA) for ide ( Leuciscus idus ) sperm activation and analysis with a CASA system. It was found that ide sperm can be activated using each AS within a pH range of 7.4-9.0 and an osmolality range of 160-200 mOsm kg -1 . The effect of Woynarovich and Perchec solutions supplemented with BSA and casein at concentrations of 0.25, 0.5, 1.0, and 2.0% were also analyzed during the experiment. These two AS without protein supplementation (pure solutions) were the controls. Woynarovich and Perchec solutions supplemented with the minimum BSA concentration (i.e., 0.25%) significantly improved sperm motility (89.05% and 86.63%, respectively) compared to the controls (20.39 and 28.48%, respectively). Similar increases were also noted in progressively motile sperm (PRG, %), the curvilinear velocity of sperm (VCL, µm s -1 ), and the amplitude of lateral head displacement (ALH, µm). A similar trend in CASA parameters was also noted when casein was added to Woynarovich and Perchec solutions at a concentration of 0.25%. We concluded that 0.25% doses of each of the proteins were sufficient to prevent sperm adhesion to glass slides, and they can be used in research on ide sperm motility measurements.

The aim of this study was to describe the selected stages of embryonic development in Siberian sturgeon ( Acipenser baerii ) and hybrids of Siberian sturgeons and Russian sturgeons ( Acipenser baerii × Acipenser gueldenstaedtii ). For this purpose, embryos representing nine distinct developmental stages (stage 1-2.0 hpf, stage 2-5.5 hpf, stage 3-13.0 hpf, stage 4-20.0 hpf, stage 5-24.0 hpf, stage 6-26.0 hpf, stage 7-35.0 hpf, stage 8-55.0 hpf, and, stage 9-160.0 hpf; hpf-hours postfertilization) were sampled from each group (group A, group B, and group C) during incubation. Stages of embryogenesis were identified based on a 30-point scale of embryonic development in sturgeons. A total of 13 developmental stages were identified, including early cleavage, blastula formation, early and late gastrulation, onset of neurulation, beginning of organogenesis, and prelarvae. During gastrulation, the survival of hybrid embryos was highest in group B (93.8%) and lowest in group A (86.7%). Embryonic deformation was not observed during experimental incubation. The archived data relating to the embryonic development of Siberian sturgeon × Russian sturgeon hybrids could be applied to identify the individual stages of embryogenesis in hybrid sturgeons during egg incubation.

In cyprinids, Tyrode's (TLP) and Volckaert's (VRT) solutions are the most frequently used extenders for short-term sperm storage. The effectiveness of TLP and VRT on ide (Leuciscus idus) sperm short-term storage was analyzed using a × 4 (sperm:extender) dilution ratio over 48 h. A × 4 (1:3) dilution ratio was compared to a × 10 (1:9) dilution ratio for ide sperm storage using TLP supplemented with antibiotics and was tested for a 14-day period. Sperm motility (MOT, %), progressively motile sperm (PRG, %), curvilinear velocity of sperm (VCL, µm s -1 ), movement linearity (LIN, %), beat cross frequency (BCF, Hz), and the amplitude of lateral head displacement (ALH, µm) were verified using a CASA system. After 48 h, most CASA parameters were significantly higher in TLP compared to VRT. The dilution ratio also had a significant impact (P < 0.0001) on the efficiency of ide sperm short-term storage over 14 d in comparison to undiluted sperm (control). Ide sperm diluted with TLP supplemented with penicillin/streptomycin and stored short term, regardless of the dilution ratio used, retained motility and fertilization capacity over 14 d at 4 °C. The highest embryo survival rates of 70% and 73% were noted using sperm diluted with TLP at × 4 and × 10 dilution ratios compared to 48% for raw sperm that was not stored short term., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)