Balbiani rings and puffs of the polytene chromosomes of Drosophila auraria

Cytogenetic analysis of Malpighian tubule and salivary gland polytene chromosomes of Bactrocera oleae (Dacus oleae) (Diptera: Tephritidae)

Photomaps of the Malpighian tubule and the salivary gland polytene chromosomes of Bactrocera oleae (Dacus oleae) are presented and compared with those of the fat body. Five polytene chromosomes (10 polytene arms) corresponding to the five autosomes of the mitotic nuclei, as well as a heterochromatic mass corresponding to the sex chromosomes, are observed in the nuclei of the three somatic tissues. The most prominent features of each polytene chromosome, the reverse tandem duplications, as well as the rather unusual ectopic pairing of the telomeric regions of different chromosome arms, are described. The constancy of the banding pattern based on the analysis of the three larval tissues is discussed.

Formation and morphology of dark puffs in Drosophila melanogaster polytene chromosomes

The formation of unusual dark puffs in Drosophila melanogaster polytene chromosomes has been studied by electron microscopic (EM) analysis. Fly stocks transformed by the P[ry; Prat:bw] and P[hs-BRC-z1] constructs were used. In the former the bw gene is under the promoter of a housekeeping gene, Prat; in the latter the Br-C locus, mapping to the dark puff 2B, is under the promoter of a heat-shock gene, hsp70. Inserted into region 65A of the 3L chromosome, the Prat:bw copies give rise to structures which are morphologically reminiscent of the so-called "dark" puffs. In contrast, insertion of P[hs-BRC-z1] into region 99B of the 3R chromosome causes a regular "light" puff of form. Comparative analysis of the dark puffs--both transgenic and natural--suggests that there might be at least two mechanisms underlying their formation. One is a local incomplete decondensation of activated bands, characteristic of the so-called small puffs. The other is the formation of ectopic-looking contacts between the bands adjacent to the puffing zone. Transposition of the DNA, from which such a puff develops, causes a regular light puff to form at the new location. Heterochromatic regions do not appear to be directly involved in puffing.

Patterns of puffing activity in the salivary gland polytene chromosomes of the medfly Ceratitis capitata, during larval and prepupal development

The patterns of puffing activity in the salivary gland polytene chromosomes have been studied during the late larval and prepupal stages of the medfly Ceratitis capitata. A total of 128 loci, with significant changes in puffing activity during this developmental period, were assigned to the five autosomes of the medfly. Two waves of puffing activity were observed, the first during the late larval stage and the second during the prepupal development. Overall puffing activity can be divided into four groups, group-IV activity being most conspicuous with 58 active loci. The major changes in puffing activity take place around jumping, a characteristic event occurring about 6 h before puparium formation, at puparium formation, and during midprepupal development. The overall puffing activity shows a positive correlation to the ecdysone titer in the hemolymph, suggesting that most of the changes in the activity of the puffs during the late larval and prepupal stages of the medfly may be regulated by ecdysone.Key words: polytene chromosomes, puffing patterns, ecdysone, Ceratitis capitata.

The organization of the alpha-tubulin gene family in the Drosophila montium subgroup of the melanogaster species group

The alpha 1-, alpha 2-, alpha 3-, and alpha 4-tubulin genes have been mapped by in situ hybridization to the polytene chromosomes of five species representative of the Drosophila montium subgroup geographical distribution. A lambda phage clone containing alpha 1-tubulin specific sequences was isolated from a genomic DNA library of Drosophila auraria and its restriction endonuclease pattern is presented. Both well-characterized heterologous and homologous probes were used to assess orthogonality of gene members between species groups. The in situ hybridization pattern observed in all species studied is consistent with that of Drosophila melanogaster, since alpha 1-, alpha 2-, and alpha 3-tubulin genes are located on the same polytene arm, and the alpha 4-tubulin gene is found on a different arm. Cross-hybridization was observed among alpha 1-, alpha 2-, and alpha 3-tubulin specific sequences in all species studied, using either heterologous or homologous probes. However, unlike D. melanogaster, in all montium species studied, both alpha 1- and alpha 3-tubulin specific probes hybridize to the same polytene band, indicating a clustered organization of the above genes. The chromosomal organization of this gene family would suggest that taxa within the montium subgroup are closer to their common ancestors than are the taxa in the melanogaster species group. A mode of evolution for this gene family in Drosophila is proposed.

Variations in the heat-induced protein pattern of several Drosophila montium subgroup species (Diptera:Drosophilidae)

After temperature elevation, the newly synthesized polypeptides from several Drosophila montium subgroup species, of the melanogaster species group, were analyzed in denaturing acrylamide gels. The pattern obtained is characteristic of the heat shock response already documented for many other Drosophila species, although the relative electrophoretic mobility of the "small" heat shock proteins exhibits a species-specific pattern. Based on the above pattern, the montium species are placed in three distinct groups. The present data is consistent with that previously used to propose a northeast to southwest evolutionary mode of expansion for the montium subgroup species.

The Drosophila montium subgroup species. Phylogenetic relationships based on mitochondrial DNA analysis

Mitochondrial DNA (mtDNA) restriction site maps for three Drosophila montium subgroup species of the melanogaster species group, inhabiting Indian and Afrotropical montium subgroup territories, were established. Taking into account previous mtDNA data concerning six oriental montium species, a phylogeny was established using distance-matrix and parsimony methods. Both genetic diversity and mtDNA size variations were found to be very narrow, suggesting close phylogenetic relationships among all montium species studied. The phylogenetic trees that were constructed revealed three main lineages for the montium subgroup species studied: one consisting of the Afrotropical species Drosophila seguyi, which is placed distantly from the other species, one comprising the north-oriental (Palearctic) species, and one comprising the southwestern (south-oriental, Australasian, Indian, and Afrotropical) species. The combination of the mtDNA data presented here with data from other species belonging to the melanogaster and obscura subgroups revealed two major clusters: melanogaster and obscura. The melanogaster cluster is further divided into two compact lineages, comprising the montium subgroup species and the melanogaster complex species; the species of the other complex of the melanogaster subgroup, yakuba, disperse among the obscura species. The above grouping is in agreement with the mtDNA size variations of the species. Overall, among all subgroups studied, the species of the montium subgroup seem to be the most closely related.

The heat shock genes in the Drosophila montium subgroup: chromosomal localization and evolutionary implications

The hsp70, hsp83, hsromega, and the small heat shock protein genes were mapped on the polytene chromosomes of six species, representative of the geographical distribution of the Drosophila montium subgroup of the melanogaster species group. In addition, based on hybridization conditions, the putative locus of the hsp68 gene is given. In contrast to the situation in the melanogaster subgroup species, the hsp70 locus is single in the montium species. The hsp83, hsromega and the small hsp loci are also single in the montium genomes studied here, a common feature of all Drosophila species. Among the hsp genes studied, the small hsp genes and the hsromega-homologous sequences exhibit a higher degree of divergence between the melanogaster and the montium subgroups. Our results support the idea that the montium subgroup species has a genome organization closer to that of the common ancestor compared with the melanogaster subgroup species.

The Afrotropical Drosophila montium subgroup: Balbiani ring 1, polytene chromosomes, and heat shock response of Drosophila vulcana

A detailed photographic map of the salivary gland polytene chromosomes of Drosophila vulcana, an Afrotropical species of the montium subgroup of the melanogaster group, is presented, along with chromosomal rearrangements, such as reverse tandem duplications and inversions, the well-formed Balbiani ring 1, and the most prominent puffs during normal larval and white prepupal development and after ecdysone treatment. In addition, the heat inducible protein and puffing pattern and the loci of the major heat shock genes, namely, hsp70, hsp83, the "small" hsps, and a putative hsp68, of this species were studied. In the light of the data revealed by the above studies, phylogenetic relationship among the montium subgroup species are attempted.

A Drosophila hsp70 gene contains long, antiparallel, coupled open reading frames (LAC ORFs) conserved in homologous loci

A clone isolated from a Drosophila auraria heat-shock cDNA library presents two long, antiparallel, coupled (LAC) open reading frames (ORFs). One strand ORF is 1,929 nucleotides long and exhibits great identity (87.5% at the nucleotide level and 94% at the amino acid level) with the hsp70 gene copies of D. melanogaster, while the second strand ORF, in antiparallel in-frame register arrangement, is 1,839 nucleotides long and exhibits 32% identity with a putative, recently identified, NAD(+)-dependent glutamate dehydrogenase (NAD(+)-GDH). The overlap of the two ORFs is 1,824 nucleotides long. Computational analysis shows that this LAC ORF arrangement is conserved in other hsp70 loci in a wide range of organisms, raising questions about possible evolutionary benefits of such a peculiar genomic organization.

General characteristics of the polytene chromosome from ovarian pseudonurse cells of the Drosophila melanogaster otu11 and fs(2)B mutants

Polytene chromosomes of good cytological quality from pseudonurse cells (PNCs) of fs(2)B and otu11 mutants were obtained, photomaps for otu11 mutants were constructed and the general characteristics of polytene chromosomes from salivary glands (SGs) and PNCs were compared. Three conditions were found to improve the cytological quality of PNC chromosomes: temperature below 18 degrees C, a protein-rich medium and presence of the Y-chromosome. Detailed comparison of the chromosome banding pattern from SGs and PNCs has shown only minor differences between them. The frequency of asynapsis appeared to be 10 times higher for PNC chromosomes. Despite previous reports, features such as breaks and ectopic contacts turned out to be also typical for PNC chromosomes, but with remarkably lower frequencies.

The beta-tubulin genes of Drosophila auraria are arranged in a cluster

When the beta 1-, beta 2- and beta 3-tubulin-specific DNAs from Drosophila melanogaster were used as probes to recognize tubulin-specific sequences in the chromosomes of Drosophila auraria, they were found to hybridize to the same polytene band in region 32C of the 2L polytene chromosome. Three overlapping clones were isolated from a lambda EMBL3 genomic library of D. auraria, and they all contain beta-tubulin-specific sequences based on hybridization and partial-sequencing experiments of subcloned fragments. These clones hybridize in situ to the same polytene chromosome band in region 32C and they represent an approximately 35-kb fragment of genomic DNA.

Insecticidal effects of essential oils. A study of the effects of essential oils extracted from eleven Greek aromatic plants on Drosophila auraria

Effects of the essential oils (EOs) extracted from eleven aromatic plants belonging to the Lamiaceae family (common in the Greek flora) were examined upon three different developmental stages of Drosophila auraria. All of the EOs examined exhibited insecticidal effects, either by preventing egg hatching, or by causing the death of larvae and adult flies. In several cases, malformation and/or prohibition of puparium formation was also observed.

Developmental changes in fat body and midgut chromosomes of Drosophila auraria

Changes in puffing activity of fat body (FB) and midgut (MG) chromosomes of Drosophila auraria during late larval and white prepupal development as well as after in vitro culture with or without ecdysterone were studied and compared with those of the salivary gland (SG). The Balbiani Rings characteristic of the SG chromosomes of D. auraria, are not formed in FB and MG. Most of the inverted tandem chromosomal duplications that have been found to be common to all three tissues showed differentiation of puffing activity of the bands considered to be homologous. The major early ecdysone puffs 73A and 73B (considered to be homologues of D. melanogaster puffs 74EF and 75B, respectively), together with other early ecdysone puffs were present in all three tissues. Clear intermoult and postintermoult puffs were not evident in FB and MG chromosomes. However, a small set of late ecdysone puffs could be scored in FB, while no late ecdysone puffs were abserved in MG. Other tissue-specific puffs were identified, but a very small number of them were limited to MG.

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 subgroups. Thus, D. guanche and D. subobscura must be considered as phylogenetically closely related species, belonging to the same subgroup.

Possible correlations of polypeptides and Balbiani rings in the salivary glands of Drosophila auraria Peng

Salivary glands of various stocks of Drosophila auraria and some of its close relatives were examined with a variety of electrophoretic techniques both from larval and prepupal stages, and after ecdysterone treatments, in an effort to detect possible translation products of the two Balbiani rings (BR1 and BR2) found in the salivary gland chromosomes of these species. Two polypeptides (P2 and P1), with molecular weights of 12,000 and 53,000, respectively, have been detected, the appearance of which coincides with the presence of BR2. The results do not allow the correlation of BR1 action with any specific polypeptide(s).