Preselection dating techniques
23-Nov-2019 11:48
Droplets containing single sperm of the appropriate fluorescence intensity are given a charge and electrostatically deflected into collection vessels.
The collected sperm nuclei then can be used for microinjection into eggs.
Planning the sex of cattle offspring is already practiced on a limited basis.
This procedure consists of removing embryos from the cow, identifying their potential gender, and re-implanting only those of the desired gender.
In beef cattle and sheep breeds, the male grows at a faster rate than the female and hence is preferred for meat production.
In addition, the ability to specify male or female offspring should shorten the time required for genetic improvements, since desirable traits are often associated with one or the other parent.
for a period of time sufficiently long for staining to take place uniformly but sufficiently short to preserve viability of the sperm;d) passing the sheath fluid containing the sperm through both a means for detecting the fluorescence of the stained DNA and also a cell sorting means, the means for detecting fluorescence having at least two detectors arranged such that a first detector determines the orientation of sperm on the basis of magnitude of fluorescence and controls a second detector to measure the DNA content of sperm on the basis of magnitude of fluorescence of those sperm that have been determined to be in a preselected orientation;e) selecting by said cell sorting means the sperm having a DNA content corresponding to a desired chromosome which will produce a desired gender of offspring, and separating the selected sperm from nonselected sperm; and12.
The method of claim 1, wherein said sperm are hydrodynamically oriented in the flow of sheath fluid by passing the fluid in a narrow stream through and out of a bevelled injection tip prior to being passed before said light source.18.
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In orthogonal flow cytometry, a suspension of single cells stained with a fluorochrome is made to flow in a narrow stream intersecting an excitation source (laser beam).
All but one pair of chromosomes are called autosomes and carry genes for all the characteristics of the body, such as skin, hair and eye color, mature size, and body characteristics. They carry the genetic material that specifies gender. A sperm from the male or an egg from the female contains one of each pair of autosomes; in addition, in mammals the egg always contains an X chromosome, while the sperm always carries either an X or Y chromosome. 121-134 (1986)] and the chinchilla [(Johnson et al. However, preparation procedures damaged DNA viability. The sorting of sperm nuclei from several mammalian (bull, boar, ram, vole, chincilla) species into separate X and Y chromosome-bearing populations at purities ranging from 92 to 99% has been accomplished [Johnson and Clarke, Gam. It is an object of this invention to provide a method for sorting mammalian sperm into X and Y chromosome fractions based on DNA content.
When a sperm and egg unite and the sperm carries the Y chromosome, the offspring is male (XY); however, if the sperm carries an X chromosome when it unites with the egg, the resulting offspring is female (XX). It is a further object of this invention to teach a method of staining the DNA of mammalian sperm while maintaining viability of the sperm.
However, an ability to separate sperm into male-producing and female-producing groups before they are used for artificial insemination could enhance the overall value of offspring produced by embryo transfer.
Every living being has a set of paired chromosomes, which carry all the genetic material necessary to maintain life and also to propagate new life. Nuclear decondensation and pronuclear development was demonstrated in hamster eggs that had been microinjected with sorted X- or Y-bearing bull, boar, or ram sperm [Johnson and Clarke, supra].
Fluorescent signals are collected simultaneously by 90 and 0 degree optical detectors, from the edge and flat side of the sperm nucleus, respectively.
