Assessment of viability and acrosomal status of Asian elephant (Elephas maximus) sperm after treatment with calcium ionophore and heparin

Knowledge about the acrosomal status of Asian elephant (Elephas maximus) sperm is extremely limited. The objective of this study was to evaluate the viability and acrosomal status of Asian elephant sperm following induction by calcium ionophore and heparin using propidium iodide (PI) and fluorescein isothiocyanate conjugated peanut agglutinin (FITC-PNA). Semen samples were collected from elephant bulls by manual stimulation. Semen was diluted with extender, cooled to 4°C and transported to a laboratory for the experiment. Sperm cells were incubated in modified Tyrode's medium containing either 1mM calcium ionophore or 10 mg/mℓ heparin for 5 h at 39°C. Sperm recovered at the onset (0 h), 1, 2, 3, 4 and 5 h of incubation were simultaneously assessed for the viability and acrosomal status using dual staining of FITC-PNA and PI. Results were confirmed by transmission electron microscopy. A progressive increase in the proportion of live-acrosome reacted sperm was observed within 3 h of incubation in both treatment groups which slightly decreased at 4 to5 h of incubation. At 1 to 3 h of incubation, the percentage of live-acrosome reacted sperm induced by calcium ionophore was higher (P < 0.05) than those induced by heparin and the control. However, there were no statistical differences at 4 to 5 h of incubation. A progressive reduction of the percentage of motile sperm was observed in the control as well as both treatment groups. Sperm motility decreased sharply when they were incubated in calcium ionophore compared with incubation in heparin and control groups. These results indicate that the occurrence of live-acrosome reacted sperm in the Asian elephant was induced by calcium ionophore at a rate higher than that induced by heparin

Effect of pre-freeze semen quality, extender and cryoprotectant on the post-thaw quality of Asian elephant (Elephas maximus indicus) semen.

Semen cryopreservation and artificial insemination (AI) are potentially valuable methods for supporting the breeding management of endangered species like the Asian elephant. Cryopreservation of Asian elephant semen has however proven problematic with respect to maintenance of both adequate semen quality and fertility post-thaw. In this study, nine ejaculates from three adult bulls were used to compare the influence of extender (TEST versus INRA96 ) and penetrating cryoprotectants (3% glycerol, 5% glycerol and 4% methylformamide) on post-thaw semen quality. We demonstrate that not only the freezing process, but also the quality of the semen before freezing, significantly influences the freezability of Asian elephant semen. Pre-freeze motility, viability, semen volume, semen pH, sperm concentration and the incidence of sperm mid-piece and tail abnormalities all significantly (p < 0.05) affected post-thaw semen quality. While extender and cryoprotectant did not significantly affect any of the above semen quality parameters post-thaw, the skim-milk based extender (INRA96 ) preserved DNA integrity better (p < 0.05) than the egg yolk extender (TEST). Considerable between-ejaculate variation in all post-thaw semen quality parameters was also noted. It is concluded that strict criteria for semen quality is essential for the selection of Asian elephant bull ejaculates suitable for cryopreservation; stricter initial selection should improve the mean post-thaw quality.EU-Asia-Link Project ‘‘Managing the Health and Reproduction of Elephant Populations in Asia’’ (TH/Asia Link/012: 9141055)http://www.elsevier.com/locate/ycryohb201

The epigenetic role of vitamin C in health and disease

Recent advances have uncovered a previously unknown function of vitamin C in epigenetic regulation. Vitamin C exists predominantly as an ascorbate anion under physiological pH conditions. Ascorbate was discovered as a cofactor for methylcytosine dioxygenases that are responsible for DNA demethylation, and also as a likely cofactor for some JmjC domain-containing histone demethylases that catalyze histone demethylation. Variation in ascorbate bioavailability thus can influence the demethylation of both DNA and histone, further leading to different phenotypic presentations. Ascorbate deficiency can be presented systematically, spatially and temporally in different tissues at the different stages of development and aging. Here, we review how ascorbate deficiency could potentially be involved in embryonic and postnatal development, and plays a role in various diseases such as neurodegeneration and cancer through epigenetic dysregulation