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V. G. PURSEL and E. F. GRAHAM

Summary.

Spermatozoal and seminal plasma lipids of fourteen individual bulls were separated by column chromatography into neutral lipid and several phospholipid fractions. Elution progress was monitored by thin-layer chromatography. Each phospholipid constituent was determined by phosphorus analysis. Total lipid, cholesterol and plasmalogen contents were determined. The fatty acids and aldehydes of the choline and ethanolamine phosphatide fractions were analysed by gasliquid chromatography.

The spermatozoal phospholipid comprised 35·6% phosphatidyl choline, 28% phosphatidal choline, 20% phosphatidyl ethanolamine, 7·2% phosphatidal ethanolamine and 9·1% sphingomyelin.

The seminal plasma phospholipid comprised 30% phosphatidyl choline, 23·6% phosphatidal choline, 10·5% phosphatidyl ethanolamine, 16·3% phosphatidal ethanolamine, 14·1% sphingomyelin and 5·4% polyglycerol phosphatide.

Myristaldehyde and palmitaldehyde were the only aldehydes identified in the choline and ethanolamine phosphatide fractions. Docosahexaenoic acid constituted a large portion of the fatty acids of spermatozoal choline phosphatide.

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V. G. PURSEL, L. A. JOHNSON and A. B. BORKOVEC

Animal Physiology and Genetics Institute, and Agricultural Environmental Quality Institute, U.S. Department of Agriculture, Beltsville, Maryland 20705, U.S.A.

(Received 20th May 1975)

Numerous studies have demonstrated the value of using heterospermic inseminations for comparing the fertilizing capacity of males (Edwards, 1955; Beatty, 1957, 1960; Beatty et al., 1969; Stewart et al., 1974; Overstreet & Adams, 1971; Martin & Reimers, 1973) and for assessing sperm treatments (Roche et al., 1968; Miller et al., 1969; Dziuk, 1970; O'Reilly et al., 1972). Overstreet & Adams (1971) and Bedford & Overstreet (1972) showed that X-irradiation of rabbit spermatozoa in vitro effectively 'marked' the sperm nucleus without affecting the fertilizing capacity. Ova fertilized by the 'marked' spermatozoa have retarded cleavage. The 'marked' spermatozoa were mixed with unmarked spermatozoa from the same ejaculate and used to test the comparative fertilizing capacity after different sperm treatments were superimposed on the two sperm populations.

Taber & Borkovec (1969)

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T. L. AVERY, M. L. FAHNING, V. G. PURSEL and E. F. GRAHAM

Summary.

Thirty inovulations of bovine ova were conducted. Superovulated ova as well as ova from single points of ovulation were transferred by both surgical and non-surgical means to synchronized and non-synchronized recipients. Two transfers entailed the use of follicular ova.

None of fourteen non-surgical transfers, made via the cervix or via the rectum, definitely resulted in pregnancy, nor did twelve transfers conducted by depositing ova within the peritoneal cavities of selected hosts.

One of four transfers, conducted by means of laparotomy, resulted in pregnancy and terminated in the full term birth of a 98-lb bull calf.

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N. A. Ahmed, M. H. Salem, H. A. El-Oksh and V. G. Pursel

Summary. The effects of incubation time (15 min–4 h), rate of semen to buffer dilution (1/10–1/40), and concentration of glucose (5·5–22 mm) on the rate of protein synthesis by ejaculated washed ram spermatozoa were determined. The rate of protein synthesis increased linearly as incubation time, dilution rate, and the glucose concentration increased. Denaturation of sperm protein with 1% HgCl2 caused an almost complete inhibition of amino acid incorporation. Protein synthesis over a period of 4 h was also inhibited by chloramphenicol but was not affected by cycloheximide. Protein synthesis and uptake of [14C]cAMP by washed ram spermatozoa was also significantly inhibited by the inclusion of 2–8% seminal plasma in the buffer. The present results indicate that the authentic protein synthesis by mature ram spermatozoa is mainly of mitochondrial origin. The data also suggest a role for intracellular cAMP in the regulation of sperm protein synthetic activity.

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J. G. Howard, M. Bush, V. de Vos, M. C. Schiewe, V. G. Pursel and D. E. Wildt

Summary. Electroejaculates from free-ranging, African elephants were frozen to test various seminal diluents, freezing methods and thawing media on post-thaw sperm viability and structural integrity. In Study I, each ejaculate was tested with each of 7 cryoprotective diluents. After cooling to 5°C and equilibration on ice (4°C) for 120 min, each aliquant was pellet frozen on solid CO2, stored in liquid nitrogen and thawed (37°C) in saline or tissue culture solution. Amongst all diluents, post-thaw sperm motility, motility duration in vitro (37°C) and acrosomal integrity were greatest (P < 0·05) when diluent BF5F was used. Thawing medium had no effect on results. In Study II, the optimal diluent from Study I (BF5F) was compared with the diluent SGI. Results were not affected by a 90- or a 150-min cooling–equilibration interval in an electronic cooler (5°C); however, post-thaw sperm motility rating and duration of motility in vitro were greater (P <0·01) with the pellet than the straw container freezing method. When the pelleting method was used, diluents BF5F and SGI provided comparable cryoprotection. Duration of post-thaw motility was enhanced 2-fold and up to 12h by maintaining thawed semen at 21 rather than 37°C (P <0·05) All diluents provided some protection on acrosomal integrity, but the overall proportion of intact acrosomes after thawing was markedly less in Study II, apparently as a result of the slower initial cooling rate (∼1·5°C/min) compared to that of Study I (∼6·5°C/min). This study demonstrates the feasibility of cryopreserving semen from free-ranging African elephants and indicates that spermatozoa must effectively survive freezing when the BF5F or SGI diluent is used in conjunction with the pelleting method.