Correlation between constitutive heterochromatin and restriction enzyme resistant chromatin in Arcyptera tornosi (Orthoptera)

Abstract

Fixed mitotic chromosomes of A. tornosi have been analysed by means of C-banding, DA-DAPI and Chromomicin A3 fluorescence, as well as by digestion in situ with Alu I, Hae III, Hinf I and Hind III restriction endonucleases. From the results obtained at least nine types of chromatin can be distinguished in A. tornosi. Some C-band positive areas (constitutive heterochromatin) which show a characteristic fluorescence pattern are digested by specific endonucleases, whilst others are undigested. C-band negative areas (euchromatin) are digested by some restriction endonucleases but not by others. Regions digested are supposed to contain highly repetitive DNAs. It is noteworthy, however, that the heterochromatin associated with NORs is not attacked by any of the enzymes we used, while regions believed to contain AT-rich DNA (DA-DAPI positive) are digested by Hae Ill that cleaves the GGCC base sequence target.

Cytogenetic analysis on the gall generation of two aphid species:Tetraneura nigriabdominalisandT. ulmi

“…The convergence between CMA 3 and AgN0 3 positive regions in T. nigriabdominalis and T. ulmi can probably be attributed to a high G-C content in the regions coding for the 18S and 28S subunit or perhaps in the intergenic spacers (RITossA and SPIEGELMAN 1965;WALLACE and BIRNSTIEL 1969). NOR-and CMA 3 -positive regions are also known to converge in other plants (ScHWEIZER 1976;LoZANO et al 1990), invertebrates (ScHWEIZER et al 1983GosALVEZ et al 1987;LoPEZ FERNANDEZ et al 1989) andvertebrates (SCHMID 1980;MAYR et al 1978). However, we should point out that, givel} the specificity of the silver nitrate stain for acid proteins associated with newly transcribed rRNA and not for rDNA, only the NOR transcriptionally active in the preceding interphase are stained with AgN0 3 (HowELL 1977;ScHWARZACHER et al 1978).…”

Evidence of separate karyotype evolutionary pathway in Euglossa orchid bees by cytogenetic analyses

“…Quinacrine mustard was used according to Schmid (1980). G banding was carried according to Seabright (1971) and restriction banding with DraI (AAA/TTT) and HaeIII (CC/GG) as reported by Gosálvez et al (1987).…”

Characterization of the karyotype of the tench (<i>Tinca tinca</i> L.) and analysis of its chromosomal heterochromatic regions by C-banding, Ag-staining, and restriction endonuclease banding

“…1985;De Stefano et al, 1986;Mezza notte, 1986;Gosálvez et al, 1987). In a previous study on the salmonid fish species Salmo trulla (brown trout), some inkling of the DNA composition in heterochromatic regions was ob tained by analysis of the digestion patterns produced by the dif ferent restriction enzymes employed (Sánchez et al" 1990).…”