[Effects of homeotic mutations. I. Pleiotropic effect of aristapedia homeotic mutations].
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Biomedical subjects
Publications and source records attributed to V A Mglinets.
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It has been generally assumed that the initial rudiment of the heart ventricle is divided by the longitudinal interventricular septum into the right and left ventricles. This paper presents evidence for the hypothesis that the right and the left ventricles are produced during normal development from different sequentially located segments of the cardiac tube. These segments yielding rudiments of the right and left ventricles could be detected even during early embryogenesis. This hypothesis requires a new explanation for the process of the formation of two separate outlets from the heart ventricles.
We studied dermatoglyphic imprints of patients with preaxial or postaxial polydactyly. Development of the additional finger is shown to be always accompanied by the corresponding finger triradius and basic line; postaxial polydactylies are characterized by the circular epidermal ridges around the rudiment of the sixth finger and the presence of the second additional triradius. On the basis of these data we suggest that major lines of the palm and finger triradii serve as landmarks denoting the borders of individual morphogenetic fields of fingers during their segregation from general morphogenetic field of the hand which is related to the polar system of coordinates.
Dermatologlyphic prints of 9 patients with preaxial (radial) hand defects were compared with control ones. A correspondence is revealed between a decrease in thumb phalanx length and a respective decrease in ridge count, on the one hand, and between the 1st metacarpal hypo- or aplasia and a decrease in palmar ridge count between the metacarpo-phalangeal and thumb flexion creases, on the other hand. An interrelation is found between the anomalies in flexion crease and respective joint formation. It is suggested, that these disorders are due to genetically determined anomalies in morphogenetic gradients which control the distribution of positional information in upper limb morphogenetic field.
Dermatoglyphic traits were examined in 176 inhabitants (39 families) of a village in Arkhangelsk Province. The level of bilateral symmetry and the similarity of the traits were determined in parents, in parents-children pairs, and between children. It is suggested that differences in the level of bilateral symmetry between children and the extent of similarity between children and parents may be used as a criterion of stability or developmental homeostasis in man.
Relative length and ridge count in dermatoglyphs of patients with various forms of brachydactyly were compared to those of the corresponding controls. In most cases of brachydactyly, fingers shortening was associated with the decreased ridge count, and only in two patients with brachydactyly D this relationship wasn't detected. It appears that brachydactyly may be due either to the abnormal positional information or disturbed function of certain growth factors responsible for the expression of inborn growth potential.
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In Drosophila puparium is a cuticular mould of external structures formed by the larval cells and can, therefore, preserve traces of developmental defects which appeared in embryogenesis. In this way ontogenetic relationship between embryonic defects and developmental defects in adult individuals can be established. The normal pattern of segmentation in puparia of Drosophila melanogaster was established by comparing segmentation defects in adult flies and corresponding puparia. Boundaries of segment and compartments have been determined, imaginal rudiments of abdominal segments (nests of histoblasts) and rudiments of trachea have been localized on puparia.
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A pattern of cuticular mosaicism for X-chromosome markers and for haplo-4 Minute phenotype was studied. Losses of either X- or IV-chromosomes were found to occur mainly in the first two cleavage divisions, being several times higher in the 1st one. X- or IV-chromosomes may be lost either separately or together, the nonrandom coincidence of joint losses in the successive divisions being observed in the latter case. No proliferation delay was found due to Minute (4) gene hemizygosity while this condition caused some enhancement in ssak expression (intersegmental fusions in tarsi) and pronounced suppression of the Hw effect.
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Establishment of egg polarity, separation of germ layers, appearance of animal-vegetal, dorsoventral and anteroposterior axis in Xenopus laevis embryos have been considered. The control of these processes by genes coding for growth factors, protooncogenes and homeobox-containing genes has also been reviewed.
We analyzed dermatoglyphic patterns of patients with pre- and postaxial polydactylies. It was found that (i) an additional finger was always accompanied by the respective digital triradius, radiants and the main line, and (ii) in postaxial polydactylies a circular pattern of epidermal ridges around the 6th finger and a 2nd additional triradius are formed. On this basis it is suggested that the palmar main lines, radiants and digital triradii serve as marker structures and borders in the process of differentiation of digital morphogenetic fields out of a unitary field organized in a fashion described by a polar coordinate system model.
The comparative dermatoglyphic analysis of palms and fingers of seven children with different forms of macrodactyly showed that they are fairly similar to those of normal children. The differences concern certain flattening of papillary ridges and reduced parameters of the total ridge count in the patients. Only in two cases of macrodactyly an increase in the relative length of fingers was accompanied by an increase in number of epidermal ridges and in the distance between fingers. If macrodactyly is based on somatic mutations or recombinations, then, depending on the time when the resulting mutant cell clones appear (before or after the epidermal ridges are laid down), the increased size of finger rudiments will or will not affect the value of ridge count.
Dermatoglyphic traits were analyzed in 132 patients with Down syndrome. The level of bilateral symmetry of dermatoglyphic indices in these patients was found to be higher than in normal people (control). By this parameter, patients with Down syndrome showed lower intragroup variation than the control group. It is suggested that such difference is due to a more primitive developmental pathway.