No abstract

The DNA methylation pattern of Vicia faba metaphase chromosomes was examined with a specific monoclonal antibody. 5-methylcytosine (5-mC) residues are present in different chromosomal sites, and are particularly abundant in telomeric and/or subtelomeric regions and in certain intercalary bands. Chromosomal localization of methylated regions enables a better knowledge of the lengthwise differentiation of this chromosome complement. Our results also indicate that there may be differences in monoclonal antibody binding between corresponding regions of homologous chromosomes in V. faba. This behaviour is detectable in specific regions with different frequencies. The data support results previously obtained for Allium cepa metaphase chromosomes using the same monoclonal antibody.

A histological, cytochemical, and ultrastructural investigation of seeds of control (nonshedding) and shedding fruits of Malus domestica Borkh. showed differences in the pattern of nutrient distribution. The kind and amount of storage compounds in the two seeds also differed. Protein bodies and starch were abundant in the control seeds and nearly absent in the seeds of shedding fruit. In the latter, there was a great abundance of phenols that exhibited a specific distribution in different tissues of the chalazal region. A cuticle was present on the inner side of the inner integument of the seeds of both control and shedding fruits. This cuticle was interrupted in the chalaza and formed a pathway for nutrient translocation, what we termed the "window." Cell wall changes observed in the chalazal window were probably associated with the different distribution pattern of storage compounds and with the control of nutrient routing. The delayed and variable development of the embryos of seeds in shed fruits may be related to both the altered pattern of storage substances and their translocation to the embryo.

No abstract

No abstract