Gene activity of polytene chromosomes in Drosophila species of the obscura group.

The polytene chromosome puffing patterns of Drosophila guanche were established and compared with those of Drosophila subobscura. A total of 150 loci, active in some of the 17 developmental stages studied, were described and 23 of them were found to form the characteristic puffing pattern of D. guanche. Taking into account the number of puffs as well as the gene activity of each chromosome and the total gene activity, D. guanche seems to be less active than D. subobscura. Although both species show a degree of homology in their puffing patterns lower than that found for sibling species, the degree of homology is stronger than that between species belonging to the same group but to different…

Heat shock proteins in three relatedDrosophila species belonging to theobscura group

The effect of heat shock on protein synthesis in three related Drosophila species belonging to the obscura group was analyzed on SDS-acrylamide gels. Four major heat shock proteins (hsps) were found in these species, in which synthesis reaches a maximum at 34 degrees C. Although the higher molecular weight proteins are conserved, differences in size were found for the small hsps in these species. By means of in situ hybridization using D. melanogaster probes for the small hsp genes, it was inferred that the small hsp genes of the obscura group species are clustered at the 27A locus in all three species.

Research Letter: is neuroticism a risk factor for postpartum depression?

Although the relationship between personality and depressive illness is complex (Shea, 2005), there is empirical evidence that some personality features such as neuroticism, harm avoidance, introversion, dependency, self-criticism or perfectionism are related to depressive illness risk (Gunderson et al. 1999). Moreover, personality traits, especially neuroticism, may explain the increased prevalence of depression among females (Goodwin & Gotlib, 2004). Few studies have explored neuroticism, extraversion and psychoticism as risk factors for depression after an event as stressful as childbirth. Pitt (1968) was the first author to report high scores on neuroticism and low scores on extraversio…

Patterns of puffing activity and chromosomal polymorphism in Drosophila subobscura : 3. Puffing activity depression by inbreeding.

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.

Common variants conferring risk of schizophrenia

Schizophrenia is a complex disorder, caused by both genetic and environmental factors and their interactions. Research on pathogenesis has traditionally focused on neurotransmitter systems in the brain, particularly those involving dopamine. Schizophrenia has been considered a separate disease for over a century, but in the absence of clear biological markers, diagnosis has historically been based on signs and symptoms. A fundamental message emerging from genome-wide association studies of copy number variations (CNVs) associated with the disease is that its genetic basis does not necessarily conform to classical nosological disease boundaries. Certain CNVs confer not only high relative ris…

Patterns of puffing activity and chromosomal polymorphism in Drosophila subobscura I. J. and U chromosomes

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…

The banding pattern of polytene chromosomes of Drosophila guanche compared with that of D. subobscura.

A detailed map of the salivary gland chromosomes of Drosophila guanche is presented and compared to the standard gene arrangements of D. subobscura. Generally, the polytene chromosomc banding patterns of the two species show a high degrce of homology. Only Segment I of the sex chromosome (Chromosome A) shows marked differences. The banding pattern proposed for this segment in D. guanche could have originated from a cluster of overlapping inversions including A1 arrangement.

Distribution of gypsy sequences in Drosophila species of the obscura subgroup.

Eight Drosophila species of the obscura subgroup were screened for sequences homologous to the gypsy retrotransposon of D. melanogaster. Molecular characterization of gypsy sequences was first approached through digesting genomic DNAs from these obscura species with appropriate restriction enzymes and subjecting them to Southern blot analysis. The results of this analysis indicate that gypsy-homologous sequences are well conserved among species of the obscura subgroup. With the exception of D. guanche, all other species bear a 7 kb Xho I fragment that represents the complete element in D. melanogaster. Lower molecular weight fragments that could be deleted elements, are shared by different …

Patterns of Puffing Activity in the Polytene Chromosomes of Drosophila Subobscura

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…

Changes in chromosomal polymorphism when selecting for a neutral trait inDrosophila subobscura

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.

Puff activity after heat shock in two species of theDrosophila obscura group

When individuals of Drosophila guanche are submitted to heat shock, five new puffs are induced. These puffs usually do not appear during normal development. Comparing these results with those obtained in Drosophila subobscura, also belonging to the obscura group, differences between the induced puffing pattern of both species have been found.

Evidence for a common origin of most Friedreich ataxia chromosomes in the Spanish population

Haplotype analysis is a powerful approach to understand the spectrum of mutations accounting for a disease in a homogeneous population. We show that haplotype variation for 10 markers linked to the Friedreich ataxia locus (FRDA) argues in favor of an important mutation homogeneity in the Spanish population, and positions the FRDA locus in the region where it has been recently isolated. We also report the finding of a new single nucleotide polymorphism called FAD1. The new marker shows a very strong linkage disequilibrium with Friedreich ataxia (FA) in both the Spanish and French populations. suggesting the existence of an ancient and widespread FRDA mutations. Inclusion of FAD1 in the exten…

Temporal changes of chromosomal polymorphism in natural populations of Drosophila subobscura

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, …

Rapid evolving RNA gene HAR1A and schizophrenia

A possible association between the CCK-AR gene and persistent auditory hallucinations in schizophrenia.

AbstractRecent studies have suggested that DNA variations in the CCK-AR gene might predispose individuals to schizophrenia and particularly to auditory hallucinations (AH). The aim of this study is to assess the association between AH, using a specific scale for AH in schizophrenia (PSYRATS), and the CCK-AR polymorphism at 779 in a Spanish sample. A total of 105 DSM-IV schizophrenic patients with AH and 93 unrelated controls were studied. Twenty-two patients were considered as persistent auditory hallucinators, which showed similar clinical and demographic characteristic than patients with episodic AH, but with the exception of the PSYRATS values. The persistent AH group showed an excess of…

A heterochromatic P sequence in the D. subobscura genome.

The study of a heterochromatic P sequence of D. subobscura reveals that it is a degraded element, located at the centromeric region of the A chromosome (X chromosome in this species), and that it is strongly diverged from the euchromatic P sequences previously described in this species. This heterochromatic sequence is composed of some P element fragments embedded in undefined beta-heterochromatic sequences. These mosaic P sequences do not show any transcriptional activity and seem to be ancient parasites of the D. subobscura genome. Phylogenetic analyses indicate that both the euchromatic and heterochromatic P sequences of D. subobscura could come from an ancestral element which was presen…

Patterns of puffing activity and chromosomal polymorphism in Drosophila subobscura II. Puffing patterns at the prepupa stage

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 …

Ultrastructure of regions containing homologous loci in polytene chromosomes of Drosophila melanogaster and Drosophila subobscura.

We have used a new approach involving in situ hybridisation and electron microscopy to establish ultrastructural homologies between polytene chromosome regions of Drosophila melanogaster and Drosophila subobscura. Twelve probes were chosen to cover all the chromosomal elements: the myospheroid gene, the collagen type IV gene, the collagen-like gene, the w26 homeobox gene, the beta3 tubulin gene, the kinesin heavy chain gene, the tryptophan hydrolase gene, the Hsp82, Hsp22-26 and Hsp23-28, Hsp68, Hsp70 genes and the beta unit of the F0-F1 ATPase gene. Most of these loci were previously undescribed in D. subobscura and imprecisely located in D. melanogaster. We have demonstrated here, by an u…

Differences in gene activity in a Drosophila species cluster belonging to the Obscura group

The polytene chromosome puffing pattern of Drosophila madeirensis was established and compared with those of the related species D. subobscura and D. guanche. A total of 145 loci, active in some of the 12 developmental stages analysed, were described, 38 of which were found to form the puffing pattern characteristic to this species. Taking into account the number of puffs as well as the mean puff expression, D. madeirensis shows a similar activity level to D. guanche, both species being less active than D. subobscura. The low gene activity of D. madeirensis and D. guanche was explained as a consequence of their ecological characteristics.

In situ localization of the Antennapedia gene on the chromosomes of nine Drosophila species of the obscura group.

The homeotic Antennapedia gene, cloned from the genomic DNA of D. subobscura, was localized on the polytene chromosomes of nine species of the Drosophila obscura group. In all of them, the probe used hybridized on chromosomes equivalent to the E element of Muller's terminology. These results are consistent with the idea that single copy genes do not move around the genome and that chromosomal elements have conserved their genetic identity during evolution.

Phylogenetic relationships between Drosophila subobscura, D. guanche and D. madeirensis based on Southern analysis of heat shock genes.

A Southern analysis of genomic DNA using Drosophila melanogaster probes for the major heat shock protein genes (Hsp82, Hsp 70, Hsps encoding small proteins) was made to study the phylogenetic relationships between three Drosophila species belonging to the obscura group (D. subobscura, D. guanche, and D. madeirensis). The phylogenetic trees showed that D. madeirensis and D. subobscura are the most closely related species in the triad, while D. guanche is the most distantly related one. As in other Drosophila species, Hsp82 is a single copy gene in D. subobscura, D. guanche, and D. madeirensis, while Hsp 70 and Hsps, which encode small proteins, are genie families. At least four sequences hom…

Structural analysis of Drosophila subobscura gypsy elements (gypsyDs)

The study of gypsy elements in Drosophila subobscura (gypsyDs) indicated that they are transcriptionally active and mobile. From the comparative analysis of a complete gypsyDs element with the canonical gypsy sequence from D. melanogaster (gypsyDm) it can be deduced that while the whole structure is maintained, the gypsyDs ORF3 encodes a non-functional Env protein. The PCR amplification and sequencing of the ORF3 from different laboratory strains and H271 clones show that all gypsyDs sequences studied have frame-shifting mutations in this region. These results support that gypsyDs elements lack functional Env proteins and consequently they lack infective ability. In this way, it can be prop…

Transcriptional and translational study of the Drosophila subobscura hsp83 gene in normal and heat-shock conditions

In this paper we report a transcriptional and translational study of the hsp83 gene of Drosophila subobscura. This gene is located at the 18C region of the J chromosome. A monoclonal antibody raised against hsp83 was used for the immunological detection of this protein by Western blotting throughout the development of D. subobscura in control and heat-shock conditions. Our results indicate that puff 18C is not only heat-shock inducible but is also expressed during normal development and its level of expression increases at the end of the prepupa period. We detected hsp83 at normal temperatures, in particular developmental stages with the exception of the larval and the beginning of prepupa…

Stress response in Drosophila subobscura

The pattern of puffing and protein synthesis was determined in individuals of Drosophila subobscura subjected to heat shock. Depending on the extent of the heat treatment, the response at the puffing level varied. Some puffs were expressed at 31°–34°C, and others at 37° C. Considering the response as a whole the depression of gene activity after shock at 31°–34° C in individuals raised at 19° C was greater than with the other treatments. Six major heat shock proteins (Hsps) were found in this species. The properties of the high molecular weight proteins are conserved their electrophoretic characteristics and the range of temperatures over which they are synthesized are close to those in oth…

178 – Promoter region of foxp2 gene: epigenetic and evolutionary analysis

Gypsy homologous sequences in Drosophila subobscura (gypsyDS).

Characterization of sequences homologous to the Drosophila melanogaster gypsy transposable element was carried out in Drosophila subobscura (gypsyDS). They were found to be widely distributed among natural populations of this species. From Southern blot and in situ analyses, these sequences appear to be mobile in this species. GypsyDS sequences are located in both euchromatic and heterochromatic regions. A complete gypsyDS sequence was isolated from a D. subobscura genomic library, and a 1.3-kb fragment which aligns with the ORF2 of the D. melanogaster gypsy element was sequenced. Comparisons of this sequence in three species (D. subobscura, D. melanogaster, and D. virilis) indicate that th…