DNA integrity of fresh and frozen canine epididymal spermatozoa

The aims of this study were to evaluate: (1) the effect of cryopreservation on DNA fragmentation of canine epididymal spermatozoa, and (2) the potential protective effect of melatonin on post-thaw sperm quality (motility, morphology, acrosomal and DNA integrity). Epididymal spermatozoa were collected after orchiectomy of ten dogs. Sperm samples were frozen in the presence or absence of melatonin (1 mM). DNA fragmentation index (percentage of spermatozoa with fragmented DNA) was similar in fresh samples (3.3 ± 3.6) and samples frozen with (4.2 ± 3.8) or without (3.6 ± 3.7) melatonin. Sperm motility was significantly (p < 0.0001) higher in fresh compared to frozen samples. The presence of melatonin in the freezing extender did not affect the sperm motility. Proportions of spermatozoa with normal morphology were similar in fresh and frozen samples, irrespective of the presence of melatonin in the extender. Acrosome integrity was significantly decreased (p < 0.01) by cryopreservation, and melatonin did not exert any beneficial effects. In conclusion, DNA fragmentation of canine epididymal spermatozoa was not affected by the freezing procedure, and the presence of melatonin did not preserve motility and acrosome integrity which were adversely affected by cryopreservation. The evaluation of DNA status of thawed gametes is particularly relevant for epididymal spermatozoa since these spermatozoa are usually stored and used in assisted reproductive techniques.     

Comparison of cryosurvival and spermatogenesis efficiency of cryopreserved neonatal mouse testicular tissue between three vitrification protocols and controlled-rate freezing

Grafting of cryopreserved testicular tissue is a promising tool for fertility and testicular function preservation in endangered species, mutant animals, or cancer patients for future use. In this study, we aimed to improve the whole neonatal mouse testicular tissue cryopreservation protocols by comparing cryosurvival, spermatogenesis, and androgen production of grafted testicular tissue after cryopreservation with three different vitrification protocols and an automated computed controlled-rate freezing. Whole neonatal mouse testes were vitrified with various vitrification solutions (V1) 40% EG + 18% Ficoll + 0.35 M Sucrose, (V2) DAP 213 (2 M DMSO + 1 M Acetamid + 3 M PG), or (V3) 15% EG + 15% PG + 0.5 M Sucrose (total solute concentration V1:74.34%, V2:44.0%, and V3:49.22% wt/vol). Alternatively, neonatal testicular tissue was also frozen in 0.7 M DMSO +5% fetal bovine serum using controlled-rate freezing and compared to fresh grafted testicular tissue, sham grafted controls, and the vitrification protocol groups. Fresh (n = 4) and frozen-thawed (n = 4) testes tissues were grafted onto the flank of castrated male NCr Nude recipient mouse. The grafts were harvested after three months. Fresh or frozen-thawed grafts with controlled-rate freezing had the highest rate of tissue survival compared to other vitrified protocols after harvesting (p < 0.05). Both controlled-rate freezing and V1 protocol groups displayed the most advanced stages of spermatogenesis with elongated spermatids and spermatozoa in 17.6 ± 1.3% and 16.3 ± 1.9% of seminiferous tubules based on histopathological evaluation, respectively. Hosts of the testicular graft from controlled-rate freezing had higher levels of serum testosterone compared to all other vitrified-thawed graft groups (p < 0.05). This study shows that completed spermatogenesis from whole neonatal mouse testes were obtained when frozen with controlled-rate freezing and V1 vitrification solution and that testicular cryopreservation efficacy vary with the protocol and vitrification technique.     

Sequential interval micro-droplet loading in closed hemi-straw carrier system: A convenient and efficient method for ultra-rapid cryopreservation in extreme oligozoospermia

Cryopreservation of human spermatozoa with low concentration while maintaining adequate post-thawing motility remains a major challenge for male fertility preservation. A convenient and efficient ultra-rapid freezing method for small amounts of human spermatozoa in a closed Hemi-Straw carrier system (CHS) was developed. Spermatozoa from 60 healthy men were involved in a parameter refining test and another 15 extreme oligozoospermic specimens were assigned to a verification test. A commercialized sperm freezing medium, Quinn's Advantage® Sperm Freeze medium (glycerol and sucrose as the cryoprotective agent) was used in the study. The results showed that the highest recovery rates would be obtained via the method of 2 μl single droplet sequential interval loading, by placing the straw at 1 cm above the liquid nitrogen (LN₂) surface for 60 s during freezing and 2 cm above the LN₂ for 2 min during thawing. This method was applied in cryopreservation for the normozoospermic specimens and compared with a conventional slow freezing method. The results were better than those in the control group in the total motility recovery rate (77.8 ± 11.2% vs 56.6 ± 11.9%, P < 0.01), progressive motility recovery rate (77.6 ± 13.2% vs 47.7 ± 14.6%, P < 0.01), 24 h survival index (60.9 ± 13.4% vs 42.1 ± 14.1%, P < 0.01) and the sperm DNA fragment index (4.2 ± 3.7% vs 5.8 ± 3.7%, P = 0.126). This method was applied to the oligozoospermic specimens. Motile spermatozoa could be found in 12 of 15 cases in the ultra-rapid freezing group, while only in 7 cases in control group. The results indicated that this freezing method was simple, convenient and bio-safe for cryopreservation of severe oligozoospermic specimens.     

Successful sperm cryopreservation of the brown-marbled grouper,Epinephelus fuscoguttatus using propylene glycol as cryoprotectant

This study developed the cryopreservation of brown-marbled grouper spermatozoa for practical application. We examined 32 cryodiluents, developed from four types of cryoprotectants [propylene glycol (PG), dimethyl-sulphoxide (Me₂SO), dimethyl-acetamide (DMA) and ethylene glycol (EG)] at four concentrations of 5, 10, 15 and 20% in combination with two extenders [Fetal bovine serum (FBS) and artificial seminal plasma (ASP). Cooling rates were examined by adjusting the height of straws (2.5–12.5 cm) from the liquid nitrogen (LN) vapor and cooled for 5 min before immersion into LN. DNA laddering was used to detect DNA damage in cryopreserved sperm. In fertilization trials, 0.5 g of eggs was mixed with cryopreserved sperm stored for 30 days in LN. The best motility of post-thaw sperm was achieved using 15% PG + 85% FBS (76.7 ± 8.8%); 10% PG + 90% FBS was also effective as cryodiluent. Generally, FBS gave better post-thaw motility compared to ASP. The optimum cooling rate was at 17.6 °C min⁻¹ obtained by freezing at the height of 7.5 cm surface of LN. The results obtained showed that cryopreserved sperm of brown-marbled grouper suffered slight DNA fragmentation, which resulted in significantly lower motility. However, the fertilization (90.9 ± 0.5%), hatching (64.5 ± 4.1%) and deformity rates (3.8 ± 0.2%) obtained from cryopreserved sperm showed no significant difference with fresh sperm. These findings show that the developed protocol for cryopreservation of brown-marbled grouper sperm was viable and will be useful for successful breeding and seed production of brown-marbled grouper.     

Effects of extender type on the quality of post-thaw giant panda (Ailuropoda melanoleuca) semen

Sperm cryopreservation is an essential approach for assisted reproduction and genetic resources conservation in captive giant pandas. Cryopreservation, however, leads to a significant decrease in sperm quality and, consequently, a low fertilization rate. Therefore, it is mandatory to disclose more suitable and efficient freezing strategies for sperm cryopreservation. In the present study, we compared for the first time the performance of two commercial freeze extender (INRA96 versus TEST) freezing methods on post-thawed semen quality. Semen cryopreserved with the INRA96 showed better total motility (73.00 ± 4.84% vs 57.56 ± 3.60%, P < 0.001), membrane integrity (60.92 ± 2.27% vs 40.53 ± 2.97%, P < 0.001) and acrosome integrity (90.39 ± 2.74% vs 84.26 ± 4.27%, P < 0.05) than stored with TEST. There was no significant difference in DNA integrity after thawing between the two extenders (95.69 ± 3.60% vs 94.26 ± 4.84%). In conclusion, the INRA96 method showed to be better for giant panda sperm cryopreservation and should therefore be recommended for use in order to increase success of artificial insemination.     

Motility and fertility of the subtropical freshwater fish streaked prochilod (Prochilodus lineatus) sperm cryopreserved in powdered coconut water

Streaked prochilod (Prochilodus lineatus) is a freshwater fish inhabiting many South American rivers. The objective was to determine the effectiveness of coconut water (ACP™), combined with methylglycol, as a freezing medium for streaked prochilod sperm. A secondary objective was to compare a computer-assisted sperm analyzer (CASA) system versus subjective microscropic examination as a means of assessing sperm motility. As a control, glucose and methylglycol was used, according to our previous study. Sperm diluted in each medium was loaded into 0.5 mL straws, frozen in liquid nitrogen vapor (in a dry shipper), and stored in liquid nitrogen (-196 °C). Half of the samples were evaluated for sperm motility, both subjectively and with CASA; the remainder were evaluated for fertility. There was no difference (P > 0.05) between subjective or CASA assessment of post-thaw sperm motility. Although sperm motility was higher in sperm cryopreserved in ACP™ (85%) than in glucose (75%), cryopreservation in either extender yielded similar fertilization rates (46-48%) and sperm velocities. There were positive correlations (r = 0.56-0.8) between all sperm velocities and fertilization rate. In conclusion, streaked prochilod sperm cryopreserved in glucose or ACP™ and methylglycol was fertile, and thus could be used for research or commercial settings. Furthermore, although the CASA system provided objective data regarding sperm motility, in the present study, subjective evaluation of sperm motility was practical and a good indication of sperm quality; it could readily be done by well-trained personnel under field or laboratory conditions.     

Changes in tri-methylation profile of lysines 4 and 27 of histone H3 in bovine blastocysts after cryopreservation

Pregnancy rates from cryopreserved embryos remain lower than non-cryopreserved counterparts, even though these embryos appear morphologically normal. How epigenetic events, such as histone modifications, are affected by cryopreservation of embryos remains unknown. The current study evaluated the effect of conventional freezing/thawing of in vitro produced bovine blastocyst embryos on histone modifications, H3K4me3 and H3K27me3. At day 7 of in vitro culture, blastocyst stage embryos were either frozen by conventional freezing method (−0.5 °C/min in 1.5 M ethylene glycol; F/T group) or remained in culture for an additional 18 h (Ctrl). Frozen embryos were stored in liquid N₂ for 14 days, thawed and placed in culture for 36 h for recovery. Control and re-expanded frozen-thawed blastocysts from both groups were fixed in 4% paraformaldehyde and stored in PBS +0.1% triton-X at 4 °C. Immunofluorescence, utilizing antibodies against H3K4me3 and H3K27me3, was conducted and staining intensity was analyzed as percentage of total DNA. Day 7 blastocyst development rate was 35.55% (352/990) with blastocyst recovery at 54.23% (77/142) 36 h post-thawing. Total cell numbers per blastocyst were not different amongst groups (117.8 ± 12.49 and 116.1 ± 14.69, F/T and Ctrl groups respectively). Global staining for the active mark, H3K4me3, was lower in F/T blastocysts compared to Ctrl (17.24 ± 2.80% vs. 34.95 ± 3.77%; P < 0.01). However, staining for the inhibitory mark, H3K27me3, was nearly 2-fold higher in F/T blastocysts (40.41 ± 3.83% vs. 21.29 ± 3.92%; P < 0.01). These results suggest that bovine blastocysts, subjected to conventional freezing methods, have altered histone modifications that may play a role in poor pregnancy rates.     

Effect of vitrification of in vitro matured prepubertal goat oocytes on embryo development after parthenogenic activation and intracytoplasmic sperm injection

This work studies the effect of vitrification of in vitro matured (IVM) prepubertal goat oocytes on: 1) oocyte damage assessed by reactive oxygen species (ROS) level and apoptosis and 2) embryo development after Intracytoplasmic sperm injection (ICSI) and Parthenogenic Activation (PA). Oocytes were IVM in supplemented TCM-199 for 22–24 h. Control group oocytes matured during 24 h were directly used for the analysis after IVM. Vitrified/warmed IVM-oocytes were vitrified after 22 h of IVM in 15% ethylene glycol (EG), 15% dimethyl sulfoxide (Me₂SO) and 0.5 M sucrose and after subjected to warming procedure. Oocyte ROS level was measured by staining denuded IVM-oocytes with 10 μM 2′7′ dichlorodihydrofluorescein diacetate. Apoptosis was analyzed by Annexin V (AV) Apoptosis Detection kit and Propidium iodide (PI) signal and oocytes were classified as: Live (AV⁻ PI⁻), early apoptotic (AV⁺ PI⁻), dead non-apoptotic (AV⁻ PI⁺) and necrotic (AV⁺ PI⁺). Developmental competence of vitrified/warmed oocytes was assessed by PA (5 min in 5 μM Ionomycin plus 4 h in 2 mM 6-Dimethylaminopurine), and by ICSI fertilization. Presumptive zygotes were in vitro cultured for 8 days in commercial media BO-IVC. Vitrified/warmed oocytes showed higher ROS levels (P < 0.0001), lower live oocytes (44 vs. 66%; P: 0.0025) and higher dead non-apoptotic oocytes (33 vs. 13% P: 0.023) compared to control. No differences were found on normal zygote formation (2 PN) (32 vs. 25%) or blastocyst development (0 vs. 4%) after ICSI fertilization. However, after PA, significant differences were found in cleavage rate (59 vs.78%; P < 0.0343) and blastocyst formation (1 vs. 25%; P < 0.0001). In conclusion, vitrification reduced oocyte competence by increasing dead oocytes and ROS levels.     

Improvement of post-thaw sperm survivals using liquid nitrogen vapor in a spermcasting oyster Ostrea angasi

Low survival of cryopreserved sperm impedes the application of cryopreservation technique in spermcasting oyster species. This study developed a simple method of liquid nitrogen vapor freezing to improve post-thaw sperm survival in the spermcasting oyster Ostrea angasi. The results indicate that the permeable cryoprotectants, dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PG) were non-toxic to sperm up to 20% concentration and 90 min exposure whereas methanol at 10% or higher was toxic to sperm for any exposure over 30 min. Among the treatments with permeable cryoprotectants, 15% EG produced the highest post-thaw sperm motility. Sperm motility was further improved by the addition of non-permeable cryoprotectants (trehalose and glucose), with 15% EG + 0.2 M trehalose resulting in the highest post-thaw sperm motility among all the combinations evaluated. The durations of 20, 30 and 60 min equilibrations produced a higher post-thaw sperm motility and plasma membrane integrity (PMI) than 10 min. Higher post-thaw motility and PMI were achieved by freezing sperm at the 8 cm height from the liquid nitrogen surface than at the 2, 4, 6, 10 or 12 cm height. Holding sperm for 10 min in liquid nitrogen vapor produced higher post-thaw motility and PMI than for 2, 5 or 20 min. The cryopreservation protocol developed in this study improved both post-thaw motility and PMI of O. angasi sperm at least 15% higher than those cryopreserved using programmable freezing method. Liquid nitrogen vapor freezing might have greater applicability in improving post-thaw sperm quality of spermcasting oyster species.     

Marked enhancement in the artemisinin content and biomass productivity in Artemisia annua L. shoots co-cultivated with Piriformospora indica

A significant enhancement in artemisinin content, an important anti-malarial compound, has been achieved in Artemisia annua L. shoots by co-cultivating with Piriformospora indica, a mycorrhiza-like fungus. The in vitro shoots derived from nodal cultures of A. annua were implanted on four different culture media namely, (i) Murashige & Skoog (MS) basal, (ii) MS + 5 μM indole-3-butyric acid (IBA), (iii) MS + P. indica and, (iv) MS + 5 μM IBA + P. indica. After 2 months, it was observed that the cultures reared on MS + 5 μM IBA + P. indica showed optimum growth in terms of shoot and root proliferation over those cultured without P. indica. The average shoot number on MS + 5 μM IBA + P. indica was 17.83 ± 1.01 and on MS + P. indica alone was 12.75 ± 1.10. A drastic decline in shoot number was observed without P. indica which was 2.0 ± 0.12 on basal and 4.9 ± 1.52 on 5 μM IBA. Similarly, a maximum average of 16.83 ± 0.82 roots were achieved on MS + 5 μM IBA + P. indica which declined to 10.75 ± 1.02 on MS + P. indica. A further decrease in root number occurred in shoots without P. indica, their average being 2.5 ± 0.12 on basal and 8.91 ± 1.57 on 5 μM IBA. HPLC analysis of the aforesaid cultures revealed that the quantity of artemisinin was significantly higher (1.30 ± 0.03 %) in shoots cultured on 5 μM IBA + P. indica compared to those of control (0.80 ± 0.01 %).     

Hybridization of tiger grouper (Epinephelus fuscoguttatus ♀) x giant grouper (Epinephelus lanceolatus ♂) using cryopreserved sperm

Using Ringer solution as extender, the present study examined the protective effect of dimethyl sulphoxide (Me₂SO; 8-12%, v/v) on the cryopreservation of giant grouper (Epinephelus lanceolatus) sperm. The cryopreserved sperm was then successfully applied in interspecific hybridization with tiger grouper (E. fuscoguttatus). Higher motility (90.56 ± 6.58%) and fertilization rate (69.61 ± 4.83%) was achieved in 10% Me₂SO with Ringer solution as extender (dilution ratio 1:1), which should no significant difference in comparison with fresh sperm (95.88 ± 1.64% and 73.10 ± 1.28%). There were no statistical differences in both fertilization and hatching rates between hybrid and non-hybrid tiger grouper by using cryopreserved sperm for fertilization, but malformation rate of the hybrid was higher than non-hybrid (17%) (P < 0.05). Survival rate of the hybrid was lower than that of the controls at 15 days post hatching (23% vs 48%). However, hybrids showed survival rate equal to the controls at the end of the 60-day study period. Hybridization of E. fuscoguttatus x E. lanceolatus was successfully achieved using cryopreserved sperm from giant grouper. The cryopreservation of giant grouper sperm and its application in hybridization provided a technical support for further grouper breeding work.     

Impact of supplementation of semen extender with antioxidants on the quality of chilled or cryopreserved Arabian stallion spermatozoa

The aim of the present study was to evaluate the effects of supplementation of semen extender with various non-enzymatic antioxidants on the quality of cooled or cryopreserved Arabian stallion spermatozoa. Semen collected from four pure Arabian stallions was centrifuged at 600g for 15 min. Spermatozoa were then diluted in INRA-82 extender supplemented with bovine serum albumin (BSA; 0, 10, 15 and 20 mg/mL) or trehalose (0, 75, 100 and 150 mM) or zinc sulphate (0, 100, 150 and 200 μM). The diluted semen was then either cooled at 5 °C or cryopreserved in 0.5–ml plastic straws. After cooling or thawing, sperm motility, viability, sperm abnormalities, viability index, and plasma membrane integrity were evaluated. The results showed that supplementation of semen extender with 150 mM trehalose or with 200 μM zinc sulphate significantly (P < 0.05) improved motility, viability, sperm membrane integrity and acrosome status in Arabian stallion spermatozoa after cooling or after freezing and thawing compared with controls (non-supplemented media) or with those supplemented with other concentrations of trehalose or zinc sulphate. Supplementation of semen extender with BSA did not improve sperm motility or cryosurvival of Arabian stallion spermatozoa after cooling or after freezing and thawing. In conclusion, supplementation of semen extender with non-enzymatic antioxidants (trehalose or zinc sulphate) improved the quality of chilled and frozen/thawed Arabian stallion spermatozoa. The most beneficial effects occur when semen diluent was supplemented with 150 mM trehalose or 200 μM zinc sulphate.     

Melatonin influence on in vitro callus induction and phenolic compound production in sweet basil (Ocimum basilicum L.)

The aim of the present study was to evaluate melatonin effects on the callus induction and phenolic compound production of Ocimum basilicum L. (sweet basil). Calluses, derived from leaf explants, were grown on Murashige and Skoog (MS) medium supplemented with 0, 100, or 200 μM melatonin, and subsequently extracted for determination of their phenolic contents. Melatonin decreased the callus induction in both concentrations. Based on the phytochemical analysis, the highest total phenolic acid contents (784.6 μg g⁻¹ and 335.2 μg g⁻¹, respectively) were recorded in calluses grown in 100 and 200 μM melatonin-supplemented medium, compared with the calluses induced with MS alone (192.0 μg g⁻¹). Among the five phenolic acids confirmed in the callus samples, rosmarinic acid was the major constituent. The amount of rosmarinic acid increased significantly in callus grown on 100 μM melatonin medium by nearly 5-fold (754.2 μg g⁻¹), compared with the control group callus. Major volatiles in basil calluses were represented by 3-methylbutanal, benzaldehyde, 1,8-cineole, 2-nonenal, eugenol, and methyl eugenol, and these were in the ranges of 4 to 14%, 24 to 50%, 2 to 3%, 0 to 0.55%, and 2 to 17% (in relative percentages), respectively. The qualitative and quantitative analyses of these substances found in calluses formed on melatonin-supplemented or melatonin-free medium were evaluated separately.

     

Novel fluorine‐containing chiral hydrazide‐hydrazones: Design,synthesis, structural elucidation,antioxidant and anticholinesterase activity,and in silico studies

In this study, a series of fluorine‐containing chiral hydrazide‐hydrazone derivatives [III‐XII] from ?‐cysteine ethyl ester hydrochloride was synthesized as new antioxidant and anticholinesterase agents. The antioxidant activity of these derivatives was evaluated by ABTS^+· and DPPH^· scavenging and CUPRAC assays and the anticholinesterase activity by the Ellman method spectrophotometrically. The results of the antioxidant assay showed that compounds V , IX , and X exhibited higher activity than BHT and α‐tocopherol used as positive standards. Among the synthesized derivatives, compound IX (IC₅₀: 2.3 ± 1.6 μM) exhibited higher acetylcholinesterase inhibitory activity than galantamine (IC₅₀: 4.5 ± 0.8 μM). Compounds XI (IC₅₀: 9.6 ± 1.0 μM), IX (IC₅₀: 12.5 ± 1.6 μM), III (IC₅₀: 16.0 ± 1.6 μM), X (IC₅₀: 17.2 ± 1.8 μM), VI (IC₅₀: 20.2 ± 0.8 μM), XII (IC₅₀: 21.5 ± 1.0 μM), and VII (IC₅₀: 24.6 ± 0.6 μM) displayed better butyrylcholinesterase inhibitory activity than galantamine (IC₅₀: 46.03 ± 0.14 μM). ADME‐Tox analysis was used to probe the drug‐like properties of the compounds. Molecular docking studies were also applied to understand the interactions between compounds and targets. The docking calculations were supported by the experimental data. In particular, compound IX , having better activity than galantamine against acetylcholinesterase and butyrylcholinesterase enzymes, was visualized using molecular docking.     

Caffeic acid improves microscopic sperm parameters and antioxidant status of buffalo (Bubalus bubalis) bull semen following freeze-thawing process

This study investigates the effects of cryopreservation and supplementation of buffalo's semen with Caffeic acid. It studies the effects of different Caffeic acid concentrations on cryopreservation capacity of the buffalo and evaluates their influence on various sperm parameters like motility, viability, progressive motility, sperm plasma membrane integrity, and antioxidant status. Twenty-four semen samples were collected with an artificial vaginal from three adult water buffalos. The semen samples were evaluated and the qualified ejaculates were separated and were diluted in a Tris-based extender. The resulting samples were classified into 5 groups: No antioxidant (control), Control sham (NaOH), Caffeic acid 50 μM, Caffeic acid 100 μM, and Caffeic acid 200 μM. The semen samples encountered cryodamage and the quality was deteriorating during the cryopreservation (P < 0.05). The semen evaluation after thawing showed that the groups of samples receiving 100 μM Caffeic acid had higher viability, total motility, and lower abnormal sperm and better linearity (LIN), curvilinear velocity (VCL), straight-line velocity (VSL) and path velocity and higher intact plasma membrane (P < 0.05) compared to other groups. It is notable that adding 100 μM Caffeic acid to freezing extenders enhances the CAT, GPx, SOD, and GSH and also ameliorates total antioxidant capacity of spermatozoa after thawing. It is notable that the addition of 100 μM Caffeic acid decreases the amount of Malondialdehyde. These reactions lead us to conclude that 100 μM Caffeic acid enhances the semen quality of water buffalo after thawing.     

The influence of cryopreservation and seminal plasma on the chromatin structure of dog spermatozoa

It was the aim of the current study to investigate effects of seminal plasma on the chromatin structure of frozen-thawed canine (Canis lupus familiaris) spermatozoa. A total of 20 ejaculates were collected. Ejaculates were divided, and one half was centrifuged for removal of seminal plasma (c) while the other was left uncentrifuged (nc) before cryopreservation. This was performed according to the Uppsala system in a computerized freezing machine. Before freezing (bf) and after thawing (at), samples were investigated for motility (M), viability (CASA), and chromatin status (sperm chromatin structure assay; SCSA). Before freezing, the average DFI% and the SD-DFI from 20 nc ejaculates were 1.7 ± 4.0% and 18.6 ± 1.2, respectively. After thawing, all motility parameters decreased and were significantly lower in centrifuged than in noncentrifuged samples, whereas the percentage of morphologically abnormal spermatozoa (Morph) was significantly higher (nc: M bf, 84.1 ± 20.6%; M at, 51.9 ± 15%; c: M bf, 84.1 ± 20.6%; M at, 43.3 ± 22.2%; Morph nc: 28.3 ± 7.8% vs. c: 31.0 ± 9.8%). Furthermore, only in c samples did the DFI increase within 6 h after thawing (DFI c: bf, 41.8 ± 1.5%; 6 h at, 45.4 ± 6.6%; P < 0.01). The SD-DFI as well as the DFI% increased within 3 h of storage in both groups (SD-DFI nc: bf, 18.6 ± 1.2%; 3 h at, 25.8 ± 5.4%; DFI% nc: bf, 1.1 ± 4.0%; 3 h at, 6.1 ± 12.9%; P < 0.05). For both parameters, there was no significant difference between c and nc samples at any time investigated. In conclusion, centrifugation of semen samples before freezing decreased postthaw motility and increased the percentage of morphologically abnormal spermatozoa as well as the degree of sperm chromatin denaturation over time. Centrifugation of canine ejaculates before cryopreservation can therefore no longer be recommended.     

Effects of melatonin on ionic currents in cultured ocular tissues

The effects of melatonin on ionic conductances in a culturedmouse lens epithelial cell line (-TN4) and in cultured human trabecular meshwork (HTM) cells were measured using the amphotericin perforated patch whole cell voltage-clamp technique. Melatonin stimulated a voltage-dependentNa⁺-selective current in lensepithelial cells and trabecular meshwork cells. The effects ofmelatonin were observed at 50 pM and were maximal at 100 µM.Melatonin enhanced activation and inactivation kinetics, but no changewas observed in the voltage dependence of activation. The results areconsistent with an increase in the total number of ion channelsavailable for activation by membrane depolarization. Melatonin was alsofound to stimulate a K⁺-selectivecurrent at high doses (1 mM). Melatonin did not affect the inwardlyrectifying K⁺ current or thedelayed rectifier type K⁺ currentthat has been described in cultured mouse lens epithelial cells. Theresults show that melatonin specifically stimulated the TTX-insensitivevoltage-dependent Na⁺ current byan apparently novel mechanism.     

Successful ultrarapid cryopreservation of wild Iberian ibex (Capra pyrenaica) spermatozoa

A method for cryopreserving wild ibex sperm at high cooling rates was developed. To design a freezing solution based on Tris, citric acid, and glucose (TCG), two preliminary experiments were performed using glycerol (GLY) and dimethyl sulfoxide (DMSO) at different concentrations (5%, 10%, 20%). The 10% GLY + 10% DMSO combination reduced (P < 0.05) frozen-thawed sperm motility, which reached a minimum when 20% GLY + 20% DMSO was used. In the second experiment, sperm tolerance to three sucrose concentrations was evaluated (100-mM sucrose, 300-mM sucrose, 500-mM sucrose). Frozen-thawed sperm motility and sperm viability decreased (P < 0.05) at concentrations above 300 mM. The ultrarapid cooling procedure finally used involved a TCG egg yolk (ey)–based extender with 100-mM sucrose, either alone or with 5% GLY with or without BSA. Two warming procedures (37 °C vs. 60 °C) were also evaluated. The TCG ey with 100-mM sucrose but without GLY/BSA returned the best sperm quality variables. Slow warming at 37 °C strongly affected (P < 0.05) sperm motility and viability in all groups. Sperm selection by density gradient centrifugation produced no motile sperm when slow warming was performed. In contrast, when fast warming was used, sperm selection increased (P < 0.05) percentage of motility, viability, and the percentage of sperms with intact acrosomes. Heterologous in vivo fertilization involving domestic goats was performed to evaluate the in vivo fertilization capacity of the ultrarapidly cooled cryopreserved sperm (in TCG-ey + 100 mM sucrose), with warming undertaken at 60 °C. Inseminations of domestic goats resulted in three pregnancies (3 of 16, 18.7% fertility). In conclusion, ibex spermatozoa are strongly sensitive to high concentrations of permeable cryoprotectants and sucrose. However, the combination of ultrarapid cooling, using TCG-ey + 100-mM sucrose, and fast warming at 60 °C, followed by sperm selection by density gradient centrifugation to collect the motile sperm, has a positive effect on sperm viability.     

Target Binding to S100B Reduces Dynamic Properties and Increases Ca2 +-Binding Affinity for Wild Type and EF-Hand Mutant Proteins

Mutations in the second EF-hand (D61N, D63N, D65N, and E72A) of S100B were used to study its Ca^2 + binding and dynamic properties in the absence and presence of a bound target, TRTK-12. With ^D63NS100B as an exception (^D63NK_D = 50 ± 9 μM), Ca^2 + binding to EF2-hand mutants were reduced by more than 8-fold in the absence of TRTK-12 (^D61NK_D = 412 ± 67 μM, ^D65NK_D = 968 ± 171 μM, and ^E72AK_D = 471 ± 133 μM), when compared to wild-type protein (^WTK_D = 56 ± 9 μM). For the TRTK-12 complexes, the Ca^2 +-binding affinity to wild type (^WT + TRTKK_D = 12 ± 10 μM) and the EF2 mutants was increased by 5- to 14-fold versus in the absence of target (^{D61N + TRTK}K_D = 29 ± 1.2 μM, ^{D63N + TRTK}K_D = 10 ± 2.2 μM, ^{D65N + TRTK}K_D = 73 ± 4.4 μM, and ^{E72A + TRTK}K_D = 18 ± 3.7 μM). In addition, R_ex, as measured using relaxation dispersion for side‐chain ¹⁵N resonances of Asn63 (^D63NS100B), was reduced upon TRTK-12 binding when measured by NMR. Likewise, backbone motions on multiple timescales (picoseconds to milliseconds) throughout wild type, ^D61NS100B, ^D63NS100B, and ^D65NS100B were lowered upon binding TRTK-12. However, the X-ray structures of Ca^2 +-bound (2.0 Å) and TRTK-bound (1.2 Å) ^D63NS100B showed no change in Ca^2 + coordination; thus, these and analogous structural data for the wild-type protein could not be used to explain how target binding increased Ca^2 +-binding affinity in solution. Therefore, a model for how S100B–TRTK‐12 complex formation increases Ca^2 + binding is discussed, which considers changes in protein dynamics upon binding the target TRTK-12.     

Cryopreservation of embryos and larvae of the edible sea urchin loxechinus albus (Molina, 1782)

The natural population of the edible red sea urchin, Loxechinus albus, is decreasing due to overfishing. The embryos and larvae of the species are highly useful for monitoring marine pollution, which makes it necessary to conserve gametes, embryos and larvae to facilitate their use in diverse areas of aquaculture and environmental quality monitoring. This need can be met by cryopreserving individuals representing the different developmental stages to provide an ongoing supply of genetic material of the species. The present study establishes a reproducible protocol for cryopreserving red sea urchin blastula and larvae. Toxicity tests were conducted in the first stage of this study using two permeable cryoprotectors, dimethyl sulfoxide (Me₂SO) and propylene glycol (PG), at three concentrations (5%, 10% and 15%). The tests were repeated in the second stage, but mixing the cryoprotectors with 0.04 M of trehalose (TRE), a non-permeable cryoprotector. Cryopreservation tests were conducted in the third stage employing different freezing rates: 2 °C/min, 3 °C/min, 3.5 °C/min, 4 °C/min and 4.5 °C/min, using the cryoprotectors that yielded the highest post-incubation survival rates.The highest post-freezing survival rates for blastula (76 ± 7%) and larvae (79 ± 7%) were obtained with Me₂SO at 10% + 0.04 M of trehalose, with freezing rates of 3 °C/min and 4.5 °C/min, respectively.