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dc.contributor.advisorKikudome, Gary Y.eng
dc.contributor.authorChang, Chia-chengeng
dc.date.issued1971eng
dc.descriptionIncludes vita.eng
dc.description.abstractThe K* knob of Mexican origin had a suppressive effect on recombination in the short arm of chromosome 9. It had the capacity to reduce recombination in both the distal and proximal regions or to reduce it only in the distal region (with a concomitant increase in recombination in the proximal region). The suppressive effect was stronger on the female-side than on the male-side. The suppressive effect of the K* knob was greatest when the chromosome containing it was opposed by a homologue which was knobless. This effect became less pronounced as the size of the opposing knob became larger. It appears that the total amount of knob material present in the bivalent was not a critical factor in this suppressive effect. In K*-containing heteromorphs, the effectiveness of the abnormal chromosome 10 in increasing recombination in the distal region was found to be progressively less as the amount of the K* knob not opposed by knob material in the homologue increased. It was also found that the greater the total amount of heterochromatin in the two knobs of the bivalent, the less effective was the abnormal chromosome 10 in increasing recombination in the proximal region. The K knob modified the B-chromosome effect on recombination. In megasporocytes of K /K heteromorphs, although total recombination in the short arm was enhanced in B-chromosome containing individuals over B-less plants, the K* knob's suppressive effect was still very much in evidence. In these heteromorphs containing the B-chromosomes, recombination was increased in both the proximal and the distal regions. In the K^S /K^S compounds the B-chromosomes did not increase total recombination in the short arm but only effected a shift in recombination from the distal to the proximal region. The K* knob did not influence the zig-zag effect on recombination induced by the odd-even number of B-chromosomes. Previous preferential segregation studies have indicated that it is the genes linked to the larger of the twoknobs of chromosome 9 bivalents which are preferentially recovered in the eggs. The K*/K^L study has provided the first exception : genes linked to the smaller K^L knob were preferentially recovered. No evidence was obtained to substantiate the possibility that the K*9 knob was functionally similar to the K10 chromosome although the K*9 and K10 knobs are morphologically quite similar. Thus it is not known whether the K*9 knob is a transposed K10 knob or not.eng
dc.description.bibrefIncludes bibliographical references.eng
dc.format.extent97 pages : illustrationseng
dc.identifier.urihttps://hdl.handle.net/10355/97405
dc.identifier.urihttps://doi.org/10.32469/10355/97405eng
dc.languageEnglisheng
dc.publisherUniversity of Missouri--Columbiaeng
dc.relation.ispartofcommunityUniversity of Missouri--Columbia. Graduate School. Theses and Dissertationseng
dc.rightsOpenAccess.eng
dc.rights.licenseThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License.
dc.sourceDigitized a department copy.eng
dc.titleCytogenetic analysis of a knobbed chromosome 9 in maizeeng
dc.typeThesiseng
thesis.degree.disciplineGenetic area program (MU)eng
thesis.degree.grantorUniversity of Missouri--Columbiaeng
thesis.degree.levelDoctoraleng
thesis.degree.namePh. D.eng


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