Recent improvements in flow cytometric sorting efficiency of X
and Y-chromosome bearing sperm of domestic animals: a review.
M.P. Gurnsey and L.A. Johnson
AgResearch, Ruakura Agricultural Research Centre, Hamilton, New
Zealand and Germplasm & Gamete Physiology Lab. ARS, USDA, Beltsville, MD
Proceedings of the New Zealand Society of Animal Production. 1998,
58: 16-18
In mammals the only method known to reliably separate X and Y
sperm for producing offspring of a specific sex is flow cytometric
sorting. This method is based on the observation that X-chromosome
bearing sperm of domestic animals contain 3.5-4.2% more DNA than
Y-chromosome bearing sperm. Relative DNA content is determined by
quantitative staining with Hoechst 33342 and DNA content measured using
a modified cell sorter. The major constraint to widespread application
of this technology has been the slow sorting rate. Using modified
standard speed cell sorters, sample flow rates average 2,000 sperm/sec
with 25-35% orientation. Recently, a high speed sorter (MoFlo®) modified
for sperm sorting has been used and increases sorting rate by
approximately 5-fold. Further, an orienting nozzle has been developed
which increases the percentage of sperm that are orientated thus
increasing the sort rate by a further 2 to 3-fold. Combined, these
improvements have increased the production of sorted sperm from
approximately 0.3 x 106/h with conventional sorters to at least 4 x 10
6/h with the high speed sorter. Preliminary testing suggests that
purity of sort and sperm viability are not compromised by increased
sorting rates. Pregnancies have been established in pigs and cows with
sorted sperm from a modified MoFlo fitted with a novel nozzle. The
improvements outlined here greatly enhance the Beltsville Sperm Sexing
Technology and make it realistic to consider trials using sex sorted
sperm for conventional AI as well as deep uterine AI in cattle.
Keywords: NZSAPAB;
X & Y-chromosome bearing sperm; flow cytometry; gender;
bovine; pig
Last Updated 12-09-1998
