General recombination mechanisms in extracts of meiotic cells

Abstract

RecA-like proteins have been purified from somatic and meiotic cells of mouse and lily. The rec proteins have been designated "s-rec" and "m-rec" to indicate their respective tissues of origin. The two proteins differ in molecular weight and in their response to temperature, the latter being consistent with the optimal temperature for physiological function of their tissues of origin. There is a major increase in m-rec protein with the entry of cells into meiosis, the peak of activity being early pachytene. Extracts of the cells and also those of yeast (Saccharomyces cerevisiae) have been prepared that have the capacity to catalyze homologous recombination. These extracts behave similarly to the m-rec proteins upon entry of cells into meiosis. Yeast transferred to sporulation medium displays a 100-fold increase in the recombination activity of the extract at about the time of entry into meiosis. The occurrence of peak levels of m-rec and recombination activity in extracts from cells in early pachytene points strongly to that stage as the time at which the enzymatic phase of recombination occurs.

Purification of DNA ligases from mouse testis and their behavior during meiosis.

“…3), as had been reported in ram spermatocytes (22). This profile of activity is similar to those of meiotic specific proteins called m-rec and recombinase, which probably catalyze meiotic recombination (9), and of DNApolymerase /3, the enzyme which is considered to function in repair and recombination reactions in both somatic and meiotic cells (19).…”

“…The amount of DNA ligase II (MW65,000) increased significantly when spermatocytes entered the prophase of meiosis, and decreased to an undetectable level in round spermatids. Meiotic recombination is known to take place during prophase, and m-rec and DNApolymerase /3 which have previously been reported to be involved in meiotic recombination (9,19), showed an activity profile similar to that of DNAligase II, which strongly suggests that DNAligase II plays some role in this reaction. originating from the contaminated Pre-P cells, was seen.…”

“…Behavior ofDNAligase I and II in meiotic process. It had been reported that frequent recombination be- tween homologous chromosomesoccurs during the prophase of meiotic division (9). To investigate whether DNAligases play any role in the final step of this event, the entire activity of DNAligases was traced over the period of premeiotic to round spermatid.…”

“…In meiotic cells, repair synthesis and subsequent recombination of DNAhave been reported to take place during the prophase period (9,10). A number of proteins which might be involved in this recombination have been purified and characterized (9, ll).…”

ATP-independent DNA strand transfer catalyzed by protein(s) from meiotic cells of the yeast Saccharomyces cerevisiae.

“…To date, it has been possible to identify DNA changes associated with recombination (3,4) and to charactenze some enzymes that may be involved (5)(6)(7). Based on studies with several organisms and human cells (see ref.…”