ISSN:
1432-0886
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Differential staining of the sister-chromatids of meiotic chromosomes of Locusta migratoria was achieved following abdominal implantation of BrdU tablets and fluorescent plus Giemsa (FPG) staining of fixed and squashed testicular follicles. This paper presents a detailed analysis of crossover exchanges between light and dark chromatids in monochiasmate bivalents. Approximately half the bivalents studied had visible exchanges of dark and light chromatids associated with the chiasmata, as expected if chiasmata originate by breakage and rejoining exchange events between randomly selected non-sister chromatids. In all the bivalents studied the visible crossover exchanges coincided exactly with chiasmata thus showing that chiasma movement (terminalisation) does not occur subsequent to crossing-over in Locusta migratoria, and that chiasmata are therefore accurate indicators of crossing over. It was noted that a proportion (9.5%) of chiasmata were associated with apparently anomalous exchanges of dark and light chromatids which could not be explained by conventional crossing-over. Various hypotheses for the origin of these anomalous exchanges are considered.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00329915
