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Analysis of DNA Levels During Gonomery in Early Cleavage Divisions of the Freshwater Copepod Mesocyclops Edax

Published online by Cambridge University Press:  02 July 2020

E.M. Rasch  and
G.A. Wyngaard
E.M. Rasch
Affiliation:
Department of Anatomy and Cell Biology, East Tennessee State University, Johnson City, TN, 37614
G.A. Wyngaard
Affiliation:
Department of Biology, James Madison University, Harrisonburg, VA22807.
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Extract

Gonomery, the separate grouping of maternal and paternal chromosomes during the first few mitoses following fertilization (Fig. 1) and chromatin diminution, the fragmentation and elimination of whole chromosome regions during specific stages of early cleavage in all primordial cells of the soma, occur in several species of copepods, ascarid nematodes, ciliated protozoa, Japanese hagfish 9 and a few other invertebrates. Because of the marked loss of DNA from all presumptive somatic cells by selective chromatin diminution during the 4th cleavage division in M. edax, it was of interest to determine DNA levels in chromosomes during gonomery in anaphases preceding diminution (Fig. 1). It was also important to estimate the DNA content of sperm as an index of the relative contribution by the male genome at fertilization in this species.

Mature males and egg-carrying females were fixed in 3:1 methanol/acetic acid for 3-5 mins, swollen in 45% acetic acid for 2-3 mins, squashed, frozen in liquid N2 for coverslip removal, thawed in 2 changes of absolute ETOH and air dried.

Type
Developmental and Reproductive Biology
Information
Microscopy and Microanalysis , Volume 3 , Issue S2: Proceedings: Microscopy & Microanalysis '97, Microscopy Society of America 55th Annual Meeting, Microbeam Analysis Society 31st Annual Meeting, Histochemical Society 48th Annual Meeting, Cleveland, Ohio, August 10-14, 1997 , August 1997 , pp. 191 - 192
Copyright
Copyright © Microscopy Society of America 1997

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