Alone among the accessions, its chromosomes had euchromatic centromeres and prominent heterochromatic
C-bands at both telomeres of chromosomes 2, 4, 6, and 7, while chromosomes 1, 3, and 5 have one prominent telomeric C-band (Fig.
labrosus from the Tibagi River as totally heterochromatic
. The results found in this study through the use of fluorochromes showed a particular heterochromatin in this supernumerary chromosome, with an abundance of GC.
Among the species used for this purpose, a special interest in the cytogenetics of the genus Stethophyma (previously named Mecostethus) arose from three main fascinating characteristics: i) the tendency for chiasmata to occur close to the centomeric regions in most bivalents (Darlington 1932; White 1936; Shaw 1970, 1971a; Jones 1971, 1973); ii) occurrence of ditactic bivalents (McClung 1928; White 1951, 1973; Shaw 1970, 1971a); iii) extended polymorphisms with respect to supernumerary heterochromatic
segments, in addition to a marked interpopulation variation for standard heterochromatin in a number of autosomes (McClung 1928; Carothers 1931; Shaw 1970, 1971a; Jones 1971; Santos unpub.
The African germplasm source has revealed the maximum amount of heterochromatic
DNA of the nine alfalfa germplasm sources studied (Bauchan and Hossain, 1998b).
Some tubules of this region, preferably those located at the beginning of the terminal zone, are lined by a simple ciliated epithelium with at least two cells types, ciliated ones and a different cell type with strongly heterochromatic
basal nucleus and a cytoplasm that reacts slightly to PAS and AB 2.5 (Figure 17).
Fitness effect analysis of heterochromatic
supernumerary segments in the grasshopper Eyprepocnemis plorans.
Use of the methylation-sensitive restriction enzyme HpaII avoided clustering of AFLP markers in recombination-deficient, heavily methylated heterochromatic
regions of the genome and permitted a more uniform distribution of markers along the seven linkage maps (Powell et al., 1997).
At this point of development, the thecal layer begins to differentiate in an inner theca of squamous cells with plane euchromatic clear ended nucleus and eosinophilic cytoplasm, and an outer theca of squamous cells with plane, fusiform, heterochromatic
nucleus and basophilic cytoplasm (Figure 5).
CADL (Cultivated Alfalfa at the Diploid Level); however, most of the heterochromatic
bands appeared at the centromeres and the telomeric ends, and few interstitial bands were observed.
Using the binomial probability distribution formula (Steel et al., 1997), it was estimated that 74 independent transformants would have been required to have a 95% probability of obtaining at least one transgene insertion in the designer chromosome (assuming comparable chromosome sizes, random integration, and lack of excessive heterochromatic
regions in the addition chromosome).
Diffuse-heterochromatic terminal C-banded regions on otherwise euchromatic chromosomes 10, 12, 17, and 21 and euchromatic terminal regions of otherwise heterochromatic
chromosomes 1C and 7C of A.