Viçosa, Brazil
Universidade Federal de Viçosa
Chromomere map of meiotic maize chromosome --Caixeta, ET, Carvalho, CR Computational and cytogenetic methods were used with the objective of mapping with high resolution, the longitudinal differentiation of maize chromosomes. Tassels of the line L-869 were collected and fixed in a methanol:acetic acid solution (3:1). Pollen mother cells were macerated with an enzymatic solution, prepared cytogenetically by the air-drying technique and later stained with a Giemsa solution. Meiotic figures were photomicrographed and digitized by means of a scanner or captured directly by a CCD video camera from microscope to a computer. The technique used allowed a visualization of well defined chromosomes that were spread out in the same focus level on the slide. The morphologic preservation of the bivalents and the almost absence of background or artifact resulted in high quality cytogenetic preparations. Digitized image analysis made the graphic plot of relative density of the chromosomes in 256 tones of gray scale possible. The profile of the gray value standards analyzed from these graphs revealed absolute and relative measures of the chromosomes. The longitudinal differentiations recognized by the centromere, knob, chromomeric and interchromomeric regions were precisely mapped throughout the meiotic chromosomes.

Figure 1. Maize pachytene chromosome number 7 and diagram showing chromomeres map. C = centromere, K=Knob.

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