Search results for "Chromosomal polymorphism"
showing 10 items of 13 documents
Patterns of puffing activity and chromosomal polymorphism in Drosophila subobscura : 3. Puffing activity depression by inbreeding.
1984
The effect of inbreeding on the puffing patterns of polytene chromosomes of Drosophila subobscura was analysed. Puffing activity was studied in two strains of D. subobscura: one which had been subject to inbreeding for 288 generations, and in the hybrids from a cross between them. A strong overall decrease in puffing activity was found in the inbred line. In general, hybrids behaved in a similar way to the inbred line or showed activity intermediate between the two lines. The fertility and viability of the two homozygous lines and of the hybrids were also determined. These parameters of fitness are very low in the inbred line. Hybrids displayed intermediate behaviour.
Patterns of puffing activity and chromosomal polymorphism in Drosophila subobscura I. J. and U chromosomes
1982
A study of the puffing patterns of the Jst, J1, U1−2, U1−2−8 and Ust chromosomal arrangements of Drosophila subobscura, from different geographical origins, has been carried out. Twenty-eight puffs were observed, 10 on the J chromosome, and 18 on the U chromosome. No differences, whether qualitative or quantitative, have been found between the puffing pattern of the J chromosome, whether from the same of different geographical background. In the U chromosome, the U1−2 and U1+2+8 arrangements show the same puffing pattern, and neither quantitative nor qualitative differences were found. However, the puffing pattern of these chromosomes alters considerably in the Ust arrangement of the K228 l…
Patterns of Puffing Activity in the Polytene Chromosomes of Drosophila Subobscura
1982
The puffs and Balbiani rings are the visible expression of sites of genetic activity (Beerman, 1952). Since Beermann’s original hypothesis, puffing patterns for several species of Diptera have been described. Thus for the genus Drosophila, Ashburner (1967, 1969a and 1969b) has reported the puffing pattern of Drosophila melanogaster and Drosophila simulans, Beredens (1965) of Drosophila hydei, and Moriwaki and Ito (1969) of Drosophila ananassae. In a previous paper Frutos and Latorre (1981) have determined puffing patterns of the J and U chromosomes of Drosophila subobscura. This species shows a rich chromosomal polymorphism and the puffing pattern of several chromosomal rearrangements of th…
Chromosomal polymorphism associated with Robertsonian fusion in Seriola dumerili (Risso, 1810) (Pisces: Carangidae)
1986
The diploid numbers 2n= 48, and 2n= 47 have been determined for the greater amberjack, Seriola dumerili. A chromosome polymorphism due to Robertsonian fusion is present in this species. A simple sex-determining mechanism has not been observed.
Changes in chromosomal polymorphism when selecting for a neutral trait inDrosophila subobscura
1986
The changes which occurred in the chromosomal polymorphism ofDrosophila subobscura when selecting for abdominal bristle number were analysed. A decrease in the diversity of arrangements and an increase in homozygosity over the selection experiment were found. These changes were stronger in selection than in control lines.
Chromosomal polymorphism and patterns of viability in natural populations of Drosophila melanogaster from cellar and vineyard.
1991
Two neighbouring natural populations of Drosophila melanogaster have been analysed, one from a cellar habitat and the other from a vineyard outside. An extensive study of inversion polymorphism in the two populations has been carried out. Furthermore, the relationship between inversion polymorphism and the viability of the second chromosome has been studied. The data regarding the total frequency of inversion-carrying chromosomes indicate a lower frequency in the cellar population than in the vineyard population. Some possibilities that could explain the behaviour of the chromosomes from the cellar in relation to the peculiar environment of this habitat are discussed. New endemic inversions…
Temporal changes of chromosomal polymorphism in natural populations of Drosophila subobscura
1984
The behaviour of the chromosomal polymorphism of D. subobscura was analyzed in relation to temporal changes, daily, seasonal and annual. Firstly, chromosome analyses were carried out over a year in a natural population. Samples were taken at monthly intervals in Tibidabo, a locality close to Barcelona. In all the months except January, the number of individuals captured was enough to carry out a chromosome analysis of that population. The A, E and O chromosomes showed a great uniformity in the frequencies of gene arrangement over the year. However, significant changes occur in the frequencies of J and U chromosomes. The J1 and U1+2+8 arrangements showed a similar tendency, with two maxima, …
Patterns of puffing activity and chromosomal polymorphism in Drosophila subobscura II. Puffing patterns at the prepupa stage
1985
Puffing activity patterns of the five large polytene chromosomes of Drosophila subobscura were studied during the late third-larval instar and through the prepupal period. A total of 166 loci active in some of the eleven stages studied were described. The distribution of these active loci per chromosome is the following: 25 on chromosome A, 33 on chromosome J, 31 on chromosome U, 34 on chromosome E and 43 on chromosome O. Seven principal patterns of puffing activity were defined taking into account the different curves of the puffing histograms. Gene activities per chromosome as well as total were analysed. Three peaks of gene activity at the beginning, middle and ending of prepupation can …
PATTERNS OF PUFFING ACTIVITY AND CHROMOSOMAL POLYMORPHISM IN DROSOPHILA SUBOBSCURA . IV. EFFECT OF INVERSIONS ON GENE EXPRESSION
1988
We have observed that, contrary to a common assumption, the puffing patterns manifest in the salivary chromosomes of Drosophila subobscura are modified by chromosomal inversions as well as by genic content. An inversion effect is apparent in the E and A chromosomes of five strains coming from four different natural populations. An effect due to the geographical location of the populations is also detected in the J and O chromosomes. The chromosomal and geographic effects are distinguishable but not contradictory. Indeed, a statistical test using the DK2 coefficient of distance shows that, for a given chromosomal arrangement, strains of different geographic origin exhibit puffing patterns si…
Inter- and intraspecific chromosome pattern variation in the yeast genusKluyveromyces
1998
The analysis of the electrophoretic chromosome patterns of the species of the genus Kluyveromyces, reveals a high polymorphism in size, number and intensity of bands. DiVerent sets of electrophoresis running conditions were used to establish species-specific patterns and also to detect intraspecific variation. According to their karyotypes, the species of this genus can be divided into two major groups. The first group includes the species K. africanus, K. bacillisporus, K. delphensis, K. lodderae, K. phaY, K. polysporus and K. yarrowii, composing the so-called ‘Saccharomyces cerevisiae-like’ group, because their karyotypes resemble that of the species S. cerevisiae. The second group compri…