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P Portin

Publications and source records attributed to P Portin.

30 records · Page 2Linked to original sources
PubMed1980

47,XXY males: sex chromosomes and tooth size.

Permanent tooth crowns of 47,XXY males were found to be generally larger than those of control males and females and their first-degree male and female relatives. These results suggest that tooth-size increase in 47,XXY males is due to a direct genetic effect and support the concept of the presence of a specific growth gene (or genes) in the human X and Y chromosomes. The effect of this gene (or genes) seems to be the promotion of tooth growth, and the Y chromosome is more effective than the X chromosome in this respect.

Adolescent↗
PubMed1977

Analysis of the negative complementation of abruptex alleles in gynandromorphs of Drosophila melanogaster.

Certain Abruptex alleles in the Notch pseudoallelic series of Drosophila melanogaster show strong negative complementation. Heterozygous combinations of some viable alleles are lethal. As a lethal system this is unique. Analysis of this type of allelic interaction in gynandromorphs suggests that the lethal focus has a fate-map site in the anterior part of the fly, probably close to the central part of the thorax. In addition to the lethal effect, negative interaction of the alleles can also be seen in the morphological level, the negative interaction of the alleles can also be seen in the morphogenesis of wings and chaetae of thorax and head. At this morphological level, the negative interaction of the alleles appears to be autonomous.

Alleles↗
PubMed1975

Allelic negative complementation at the Abruptex locus of Drosophila melanogaster.

The mutations of the Abruptex locus in Drosophila melanogaster fall into three categories. There are recessive lethal alleles and viable alleles. The latter can be divided into suppressors and nonsuppressors of Notch mutations. The recessive lethals are lethal in heterozygous combination with Notch. As a rule the recessive lethals are lethal also in heterozygous combination with the viable alleles. Heterozygous combinations of certain viable alleles are also lethal. In such heterozygotes, one heteroallele is a suppressor of Notch and the other is a nonsuppressor. Other heterozygous combinations of viable alleles are viable and have an Abruptex phenotype. The insertion of the wild allele of the Abruptex locus as an extra dose (carried by a duplication) into the chromosomal complement of the fly fully restores the viability of the otherwise lethal heterozygotes if two viable alleles are involved. The extra wild allele also restores the viability of heterozygotes in which a lethal and a suppressor allele are present. If, however, a lethal and a nonsuppressor are involved, the wild allele only partly restores the viability, and the effect of the wild allele is weakest if two lethal alleles are involved. It seems likely that of the viable alleles the suppressors of Notch are hypermorphic and the nonsuppressors are hypomorphic. The lethal alleles share properties of both types, and are possibly antimorphic mutations. It is suggested that the locus is responsible for a single function which, however, consists of two components. The hypermorphic mutations are defects of the one component and the hypomorphic mutations of the other. In heterozygotes their cumulative action leads to decreased viability. The lethal alleles are supposed to be defects of the function as a whole. The function controlled by the locus might be a regulative function.

Alleles↗
PubMed1975

The cusp of Carabelli. Occurrence in first upper molars and evaluation of its heritability.

In a Finnish rural population 79.0% of 233 persons had the cusp of Carabelli in first upper molars. Of these 20% showed "positive cusps" and 59% "negative cusps". The occurrence of the structure was bilateral with varying degrees of asymmetry, but if there was no structure on one side of the jaw, the other never showed the cusp. There was no sexual dimorphism either in the occurrence or in the degree of expression of character. Results of the statistical analyses suggested low heritability of the character. However, the dichotomy of having a cusp or not may have genetic basis, but there is large variation in the expression of the "cusp-genotype".

Female↗