Expression of 93D heat shock puff of Drosophila melanogaster in deficiency genotypes and its influence on activity of the 87C puff

Using the overlapping deficiencies Df(3R)GC14 and Df(3R)e ^Gp 4 of the 93D region of Drosophila melanogaster, the benzamide (BM)-inducible site in polytene chromsomes was localised to the 93D6-7 region, which had earlier been identified as heat inducible. The normal developmental and BM-induced 93D6-7 puff was found to be dosage compensated since in larvae heterozygotus for a deficiency, with one dose of 93D6-7, the rate of ³H-uridine incorporation in this puff was the same as in the wild type with two doses. Curiously, however, heat shock (37° C) caused regression of the 93D6-7 puff on the normal chromosome in heterozygotes. In agreement with earlier results from our laboratory, the non-inducibility of the single-dose 93D locus by heat shock in the heterozygotes, caused the 87C puff to be nearly half as active as the 87A puff at 37° C. However, in e ^Gp 4/GC14 larvae, lacking the 93D6-7 locus on both homologues, the 87C puff was less active than 87A in some heat-shocked larvae but in other larvae 87A and 87C were equally active. Possible reasons for this inter-larval variability are discussed.     

Puff expression in relation to genotype]

The studies of genotype influence on puff size in salivary gland chromosomes of Drosophila virilis (stocks 9, 101, 142, 151) and D. texana (the stock 123) reveal significant differences between the species concerning the structure of puff in the 3-C-6 region at the stage of puparium formation. In reciprocal F1 hybrids the size of the puff was intermediate in comparison with parental forms having a slight maternal effect. The differences in puff size in the 5th chromosome between interspecific hybrids and the special stock of D. virilis carrying a region of D. texana 5th chromosome in heterozygous condition (inserted into D. virilis 5the chromosome by double crossing-over) were observed. The transfer of the region of the third chromosome to near centrimetric heterochromatic of the 5th chromosome by translocation resulted in the increase in the 3-B-2 puff size. However, the transposition of the 3-B1 region in the proximal direction with respect to chromocenter did not affect the puff size.     

Cytogenetics of Notch Mutations Arising in the Unstable X Chromosome Uc of Drosophila melanogaster

A derivative of the unstable X chromosome, Uc, isolated in 1978 is still unstable and exhibits most of the genetic properties characteristic of the original Uc. This derivative, Df(1)cm-In, contains an inversion of the genes between bands 6F1-2 and 3D3-5 and a lethal deficiency between 6D5-7 and 6F1-2. This chromosome generated Notch mutations at a rate of 3.47 +/- 0.32% during seven consecutive generations. Cytological analysis of 50 Notch mutations of independent origin in the Df(1)cm-In chromosome showed that all of the 50 had an apparently identical deletion involving the region between 3D3-5 and 3C7-8 of the X chromosome. The results of in situ hybridization indicated that the extent of deletion in all of the 20 Notch deficiencies sampled from the 50 mentioned above involves about 10 kb of the sequences from the 3' end of the Notch locus. In addition to hypermutability and the accumulation of site-specific chromosome breaks, the Df(1)cm-In chromosome reinverts its inversion to the normal sequence and exhibits use of the existing chromosome breakpoints to generate new rearrangements.     

Localization of ecs, dor and swl genes in eight Drosophila species]

The DNA sequences from Drosophila melanogaster early ecdysterone-inducible puff 2B have been located in 8 Drosophila species by in situ hybridization. The location site of the ecs, dor and swi genes in D. funebris, D. virilis, D. hydei, D. repleta, D. mercatorum, D. paranaensis is a puff on the telomeric and of X chromosome; in D. kanekoi it is the puff in distal part of X chromosome; and in D. pseudoobscura it is the puff in proximal portion of X chromosome. So, conservative organization of DNA sequences located in D. melanogaster 2B puff could be suggested. Dispersed distribution of some DNA segments from the region studied in D. hydei chromosomes was revealed.     

嗜人按蚊的唾腺染色体

本文描述了我国疟疾媒介嗜人按蚊(Anopheles anthropophagus)的唾腺染色体图。此蚊的唾腺染色体由五个臂组成。第1号染色体为性染色体,又称X-染色体,是近端着丝粒,只有一个臂,它是各臂中最短的,此臂分为5个区;第2号染色体是中心着丝粒,左、右臂约等长,两臂共分为16个区;第3号染色体为亚中心着丝粒,右臂是各臂中最长的,左臂则是常染色体中最短的,两臂共分为18个区。     

Drosophila: the genetics of two major larval proteins.

A series of irradiation-induced deficiencies covering 62 polytene chromosome bands in chromosome arm 3L of Drosophila melanogaster includes the loci of two abundant developmentally regulated larval proteins. The structural gene for larval serum protein 2 (LSP 2) lies at 68E3 or 4, and that for salivary glue secretion protein 3 between 68A8 and 68C11, coincident with a major intermoult puff active in the salivary gland at the time of glue synthesis. The structural genes for esterase 6 and four visible recessive loci lie within the same region.     

Electron microscope analysis of the E polytene chromosome of Drosophila subobscura: region 70B to 72D

Revision of the reference map of the polytene chromosomes of Drosophila subobscura was started by means of the electron microscope. We present a map of regions 70B to 72D of the E chromosome obtained from squashed and thin-sectioned salivary glands. It was observed that the total number of bands in divisions 70B to 72D is considerably higher than those depicted in the reference map of Kunze-Mühl and Müller. Functional considerations are made of some regions that show puff structures.     

Modeling dark puffs using P-transposons in Drosophila melanogaster polytene chromosomes

Modeling of morphologically unusual "dark" puffs was conducted using Drosophila melanogaster strains transformed by construct P[ry; Prat:bw], in which gene brown is controlled by the promoter of the housekeeping gene Prat. In polytene chromosomes, insertions of this type were shown to form structures that are morphologically similar to small puffs. By contrast, the Broad-Complex (Br-C) locus, which normally produce a dark puff in the 2B region of the X chromosome, forms a typical light-colored puffs when transferred to the 99B region of chromosome 3R using P[hs-BRC-z1]. A comparison of transposon-induced puffs with those appearing during normal development indicates that these puff types are formed via two different mechanisms. One mechanism involves decompaction of weakly transcribed bands and is characteristic of small puffs. The other mechanism is associated with contacts between bands adjacent to the puffing zone, which leads to mixing of inactive condensed and actively transcribed decondensed material and forming of large dark puffs.     

Patterns of puffing activity in the salivary gland chromosomes of Drosophila

The autosomal salivary gland chromosome puffing patterns of Drosophila simulans are described and compared with the puffing patterns of the sibling species D. melanogaster. During the late third larval instar and the prepupal period the patterns of puffing activity of these two species are similar — approximately 50% of the puffs common to both species showing identical activities. The remaining puffs differ in their timing of activity, or in their mean sizes, or in both of these parameters. A number of puffs (14) found in D. simulans have not been regularly observed in the Oregon stock of D. melanogaster but are active in other D. melanogaster strains. One puff (46 A) of D. melanogaster was absent from D. simulans and forms a heterozygous puff in hybrids, when the homologous chromosomes are synapsed. When the homologues are asynapsed a puff at 46 A is restricted to the melanogaster homologue. The puff at 63E on chromosome arm 3L is considerably smaller in D. simulans than in D. melanogaster and this size difference is autonomous in hybrids. Other puffs not common to both species behave non-autonomously in the species hybrid, even when the homologous chromosomes are asynapsed.     

Cytogenetic analysis of the 2B3-4-2B11 Region of the X chromosome of Drosophila melanogaster

Larvae homozygous or hemizygous for the l(l) t435 mutation located within the early ecdysteroid puff 2B5, or carrying a deletion of the 2B5 band, die at the end of the third larval instar. In the salivary gland chromosomes of these larvae only intermoult puffs are detected. If these salivary glands are incubated in vitro with 20-OH ecdysone for 6 h the intermoult puff 68 C remains large, some early puffs (74EF and 75B) are induced to 30–40% of their normal size, other early (63F) and all late puffs (62E, 78D, 82F and 63E) are not induced at all. Puff 2B5 reaches its normal size but does not regress after 6h incubation with 20-OH ecdysone, as it does in normal stocks. The data obtained in this study show the existence of a locus (or loci) in the band (puff) 2B5 which is necessary for the normal response of the salivary gland chromosomes to the hormone 20-OH ecdysone.     

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.     

Cytogenetic and molecular aspects of position effect variegation in Drosophila

Variations in compaction of chromosomal material of the rearrangements Dp(1;f) 1337, Dp(1;f) R, Dp(1;1)pn2b, and T(1;4)w ^m258-21, which display an extended position effect, were characterized. Morphological changes found in these rearangements were assigned to two major types: (i) continuous compaction, in which bands and interbands located distal to the eu/heterochromatin junction fuse into one compacted block of chromatin. The extent of compaction is increased by enhancers of position effect (low temperature, removal of the Y or 2R chromosome heterochromatin). In extreme cases compaction extends over dozens of bands. (ii) Discontinuous compaction, in which at least two zones of compaction separated by morphologically normal zones can readily be identified. As a result, some regions located at a greater distance from heterochromatin may be compacted more frequently than others than map nearer to it. A few regions (1D, 2B1-12, 2D) were shown to be most frequently compacted in all rearrangements investigated. The 2B13-18, 2C1-2, 2E, and 2F regions exhibited the lowest frequencies of compaction. Compaction of the zone containing the 2B1-12 bands is always accompanied by inactivation of the ecs locus, which maps in the 2B3-5 puff. At the same time the 2C1-2 and 2E bands located nearer to the breakpoint can retain normal morphology and puffing in response to ecdysterone. The results are interpreted as morphological manifestations of the discontinuity of the spreading effect.by W. Beermann