The changes in chromosome 6 spatial organization during chromatin polytenization in the Calliphora erythrocephala Mg. (Diptera: Calliphoridae) nurse cells

Abstract

Localization of Calliphora erythrocephala chromosome 6 in a 3D nuclear space at different stages of nurse cell chromatin polytenization was analyzed by fluorescence in situ hybridization and 3D microscopy. The obtained results suggest a large-scale chromatin relocation in the C. erythrocephala nurse cell nuclei, which is accompanied by a change in the chromosome territory of chromosome 6 associated with the change in expression activity of the nucleus and formation of reticular chromatin structure. It was revealed that the relocation of chromosome 6 (nucleolus organizer chromosome) is accompanied by fragmentation of the single large nucleolus into micronucleoli, which are spread over the entire nuclear space being associated with their nucleolar organizer regions. Presumably, the chromosome 6 material during transition to a highly polytenized structure is redistributed in the nucleus so that the inactive pericentromeric regions are displaced to the nuclear periphery, while the chromosome regions carrying rDNA sequences loop out beyond the chromosome territory. Being dispersed over the entire nuclear space, rDNA sequences are likely to be amplified, thereby providing numerous small signals from the chromosome 6-specific DNA probe. Micronucleoli are formed around the actively transcribed nucleolar organizer regions.

Tissue-Specific Differences in the Spatial Interposition of X-Chromosome and 3R Chromosome Regions in the Malaria Mosquito Anopheles messeae Fall.

“…For the 3D-FISH procedure, adult mosquito ovaries (for nurse cells and follicle cells analyzing), larvae salivary glands and appendages imaginal discs were dissected and placed in PBS solution (137 mM NaCl, 2.7 mM KCl, 10 mM Na 2 HPO 4 , 1,8 mM KH 2 PO 4 ). Further 3D-FISH procedures were conducted according to the appropriate protocols [ 24 , 25 ].…”

Tissue-specific features of the X chromosome and nucleolus spatial dynamics in a malaria mosquito, Anopheles atroparvus

“…Ovaries for 3D-FISH were extracted from 3 individual mosquitoes immediately before conducting hybridization. Ovaries were dissected in 1×PBS and were processed in accordance with the 3D-FISH protocol described in our previous study [ 19 ].…”

Specific features in linear and spatial organizations of pericentromeric heterochromatin regions in polytene chromosomes of the closely related species Drosophila virilis and D. kanekoi (Diptera: Drosophilidae)

“…Endopolyploid nuclei differing in the degree of polytenization and chromatin morphology are formed in the nurse cells in endocycles S 2 -S 7 namely, primary reticular nuclei, carrying decompactised chromatin (Stegnii et al 1999;Wasserlauf et al 2003;Ananyina et al 2005;Wasserlauf 2013); polytene chromosomes (shortened chromosomes lacking a distinct banding pattern identifiable according to heterochromatin blocks in certain regions); compact pompon-like chromosomes; and secondary reticular nuclei with a reticulate chromatin pattern (Painter and Reindorp 1939;Khvostova 1947;King et al 1981;Zhimulev 1992;Stegniy et al 1996;Dej and Spradling 1999;Wasserlauf et al 2003;Ananyina et al 2005;Wasserlauf 2008Wasserlauf , 2013Kokhanenko et al 2013). Our previous results on mutual chromosome arrangement in the nurse cell nuclei of various Drosophila species were obtained in ''semi-squash'' preparations retaining chromosome spatial arrangement within a nucleus Wasserlauf 2008).…”

“…Prehybridization, hybridization, and post-hybridization steps were performed according as described in Kokhanenko et al (2013).…”