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GENETIC VARIATION IN THE ORIENTATION OF NUCLEAR SPINDLES DURING THE DEVELOPMENT OF ASCI IN NEUROSPORA
Author(s) -
Pincheira Guido,
Srb Adrian M.
Publication year - 1969
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1969.tb09734.x
Subject(s) - ascus (bryozoa) , biology , neurospora crassa , heterokaryon , spore , neurospora , mutant , crassa , zygote , genetics , meiosis , ploidy , nuclear gene , embryo , gene , botany , embryogenesis , ascospore , genome
The effect of a single mutant gene, peak‐2 , in Neurospora crassa is to alter the ascus from one in which the eight spores are linearly arranged to one in which the eight spores are arranged non‐linearly. The same gene transferred to N. tetrasperma determines an ascus similar to that of the mutant N. crassa but in striking contrast to the normal ascus for N. tetrasperma , which includes four heterokaryotic spores, linearly arranged. A comparative cytological study has been made on asci from both species, including material from zygotes that are homozygous normal, heterozygous for peak‐2 , and homozygous for peak‐2 . The observed morphogenetic differences are closely related to differences in nuclear spindle orientation, which in turn are correlated with the geometry of the cell. The observations are shown to bear on the basis of pseudohomothallism in N. tetrasperma . Speculations on the importance of the cell wall in relation to spindle orientation are presented. Differences of expression of peak‐2 in the different species are discussed.