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We adapted flow cytometry technology for high-purity sorting of X chromosome-bearing spermatozoa in the western lowland gorilla (Gorilla gorilla gorilla). Our objectives were to develop methodologies for liquid storage of semen prior to sorting, sorting of liquid-stored and frozen-thawed spermatozoa, and assessment of sorting accuracy. In study 1, the in vitro sperm characteristics of gorilla ejaculates from one male were unchanged (P > 0.05) after 8 hr of liquid storage at 15 degrees C in a non-egg yolk diluent (HEPES-buffered modified Tyrode's medium). In study 2, we examined the efficacy of sorting fresh and frozen-thawed spermatozoa using human spermatozoa as a model for gorilla spermatozoa. Ejaculates from one male were split into fresh and frozen aliquots. X-enriched samples derived from both fresh and frozen-thawed human semen were of high purity, as determined by fluorescence in situ hybridization (FISH; 90.7%+/-2.3%, overall), and contained a high proportion of morphologically normal spermatozoa (86.0%+/-1.0%, overall). In study 3, we processed liquid-stored semen from two gorillas for sorting using a modification of methods for human spermatozoa. The sort rate for enrichment of X-bearing spermatozoa was 7.3+/-2.5 spermatozoa per second. The X-enriched samples were of high purity (single-sperm PCR: 83.7%) and normal morphology (79.0%+/-3.9%). In study 4 we examined frozen-thawed gorilla semen, and the sort rate (8.3+/-2.9 X-bearing sperm/sec), purity (89.7%), and normal morphology (81.4%+/-3.4%) were comparable to those of liquid-stored semen. Depending on the male and the type of sample used (fresh or frozen-thawed), 0.8-2.2% of gorilla spermatozoa in the processed ejaculate were present in the X-enriched sample. These results demonstrate that fresh or frozen-thawed gorilla spermatozoa can be flow cytometrically sorted into samples enriched for X-bearing spermatozoa., (Copyright 2005 Wiley-Liss, Inc.)

Pre-determination of the sex of offspring has implications for management and conservation of captive wildlife species, particularly those with single sex-dominated social structures. Our goal is to adapt flow cytometry technology to sort spermatozoa of non-human primate species for use with assisted reproductive technologies. The objectives of this study were to: (i) determine the difference in DNA content between X- and Y-bearing spermatozoa (ii) sort sperm nuclei into X- and Y-enriched samples; and (iii) assess the accuracy of sorting. Spermatozoa were collected from two common marmosets (Callithrix jacchus), seven hamadryas baboons (Papio hamadryas) and two common chimpanzees (Pan troglodytes). Human spermatozoa from one male were used as a control. Sperm nuclei were stained (Hoechst 33342), incubated and analyzed using a high-speed cell sorter. Flow cytometric reanalysis of sorted samples (sort reanalysis, 10,000 events/sample) and fluorescence in situ hybridization (FISH; 500 sperm nuclei/sample) were used to evaluate accuracy of sorting. Based on fluorescence intensity of X- and Y-bearing sperm nuclei, the difference in DNA content between X and Y populations was 4.09 +/- 0.03, 4.20 +/- 0.03, 3.30 +/- 0.01, and 2.97 +/- 0.05%, for marmoset, baboon, chimpanzee and human, respectively. Sort reanalysis and FISH results were similar; combined data revealed high levels of purity for X- and Y-enriched samples (94 +/- 0.9 and 93 +/- 0.8%, 94 +/- 0.7 and 94 +/- 0.5%, 91 +/- 0.9 and 97 +/- 0.6%, 94 +/- 0.6 and 94 +/- 0.9%, for marmoset, baboon, chimpanzee and human, respectively). These data indicate the potential for high-purity sorting of spermatozoa from non-human primates.

The antioxidants superoxide dismutase (SOD), catalase (CAT), cytochrome c (CHc) and glutathione peroxidase (GP) were added at various concentrations to Tris-glucose-yolk diluent (TGY), and their effects on motility, acrosome integrity and fertility of ram spermatozoa were assessed after extension and liquid storage. All the antioxidants improved the motility and acrosome integrity of spermatozoa, and a combination of SOD and CAT had an additive effect on the survival of spermatozoa stored at 5 degrees C but not at 25 degrees C. There was a linear improvement in survival of spermatozoa with increasing dose of antioxidants except for CAT for which doses higher than 200 U mL-1 were toxic. The proportion of oocytes fertilized in vitro declined with time of semen storage (P < 0.001), and was better for semen diluted with TGY containing SOD or CAT than TGY without antioxidants when stored for 7 days (116/246, 47% v. 25/79, 32%; P < 0.05) but not for 14 days (23/174, 13% v. 8/66, 12%). Fertilization rates were unaffected by the presence or absence in the diluent of CHc or GP. The proportions of ewes with fertilized ova and of recovered ova fertilized were better after insemination with semen diluted in TGY containing SOD and CAT than TGY without antioxidants when stored for 14 days (9/18, 50% and 20/40, 50% v. 2/13, 15% and 5/32, 16%; P < 0.05) but not for 7 days (9/20, 45% and 16/48, 33% v. 8/16, 50% and 24/41, 59%). Pregnancy rates were better after intrauterine insemination of ewes with fresh semen than stored semen (11/18, 61% v. 21/75, 28%; P < 0.01), and with semen stored in TGY containing SOD and CAT than in TGY without antioxidants (15/37, 41% v. 6/38, 16%; P < 0.05).