Type of Document Master's Thesis Author Keil, Clifford B URN etd-03132009-040445 Title Basic studies of chiasma frequency in male Blattella germanica (L.) Degree Master of Science Department Entomology Advisory Committee
Advisor Name Title Ross, Mary H. Committee Chair Cochran, David G. Committee Member Grayson, James McD. Committee Member West, David A. Committee Member Keywords
Date of Defense 1979-05-05 Availability unrestricted AbstractThis investigation represents the first thorough examination
of chiasma frequency in the primitive orthopteroid insect, Blattella
germanica (L.). The data obtained are useful both in advancing our
knowledge of cockroach genetics and in stimulating comparative cytogenetic
studies. A pilot study was conducted to ascertain appropriate
sample sizes and to assess the feasibility of more extensive investigations.
Experimental animals were reared in a constant temperature and
humidity chamber and segregated according to whether they emerged from
a first, second, or third ootheca. The testes of third to fourth
instar male nymphs were removed, stained with acetic orcein, and
examined for suitable numbers of cells at diplotene-diakinesis.
Analysis of the chiasma frequency data showed a decrease in mean
chiasmata per bivalent: 1.3325 ± 0.0184 for the first oothecal group,
1.2999 ± 0.0165 for the second oothecal group, and 1.2525 ± 0.0113 for
the third oothecal group. The variances decline with the means.
The chiasma frequency of a stock heterozygous for a reciprocal
translocation involving two mid-sized chromosomes, eight and nine,
was compared to the wild-type freq9encies. In comparison with the
first oothecal group, an elevated chiasma frequency, 1.4176 ± 0.0062
chiasma per bivalent, was found. The translocation had the effect of
raising chiasma frequency in the two bivalents involved. No interchromosomal
effect on chiasma frequency was observed, due to the
presence of the translocation. It was noted that in B. germanica,
chiasma frequency is probably not positively correlated with bivalent
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