Patterns of puffing activity in the salivary gland chromosomes of Drosophila

Exposure of Drosophila melanogaster larvae to high temperature for short periods of time results in marked changes in the puffing patterns of salivary gland chromosomes. Temperature shock induces puffing at 9 specific loci; this pattern of induced puffs shows little developmental specificity and is similar in three strains of D. melanogaster (including the mutant lethal giant-larvae) and in D. simulans. Temperature shock also (i) retards the regression of some developmentally specific puffs and (ii) results in the regression of all other puffs normal to development. The effect of temperature treatment is similar in vivo and after in vitro treatment of salivary glands. The in vitro response is not sensitive to cycloheximide. A similar pattern of induced puffs to that found after temperature treatment is found during recovery of larvae from anoxia, but additional puffs are induced after anoxia. The size and duration of activity of the induced puffs is dependent upon the magnitude of the treatment.     

Patterns of puffing activity in the salivary gland chromosomes of Drosophila

Salivary gland X chromosome puffing patterns are described for the Oregon stock of Drosophila melanogaster and for the Berkeley stock of D. simulans. In D. melanogaster regular phase specific puffing was recorded at 21 loci in the third larval instar and subsequent prepupal stage. A comparison of the X chromosome puffing patterns of male and female larvae failed to show any qualitative differences although in the males a group of puffs were active for a longer time during development than in females. The X chromosome puffing patterns of D. simulans are similar to those described for D. melanogaster although two puffs (4F 1–4 and 7B 1–3) were active in D. simulans but not in D. melanogaster. The sex differences in puffing observed in D. melanogaster were also observed in D. simulans.     

Patterns of puffing activity in the salivary gland chromosomes of Drosophila

The patterns of puffing activity in the proximal region of 2L of D. melanogaster have been reinvestigated and revised. Possible relationships between three puffs and the structural genes for alcohol dehydrogenase, dopa decarboxylase and the histones are discussed.     

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.     

Patterns of puffing activity in the salivary gland chromosomes of Drosophila

The patterns of puffing activity have been studied during the late larval and prepupal stages of Drosophila melanogaster. On the major salivary gland autosomes (chromosomes 2 and 3) 108 loci form puffs at some time during these developmental stages. The timing and pattern of activity of 83 of these puffs is found to be strictly dependent upon the age of the animals. Two major peaks in puffing activity occur. The first of these is at the time of puparium formation and the second in 8 hr. old prepupae. Both of these puffing peaks precede a moult by 4 hrs. 30 puffs are active before or at the time of both of these two moults. However, the sequence of appearance and regression of many of this group of puffs is different at the prepupal moult than at the pupal moult. 12 puffs occur only before or at the time of the prepupal moult and 13 puffs only before or at the time of the pupal moult. The functional significance of these periods of puffing activity is discussed and it is concluded that one function of this genetic activity in the salivary glands of metamorphosing Drosophila is the production of substances to be utilised during the histogenesis of the adult tissues.     

Patterns of puffing activity in the salivary gland chromosomes of Drosophila

Patterns of puffing activity during the third larval instar and the prepupal period of two different strains of D. melanogaster (Oregon and vg6) are compared. The variation in puffing activity observed is both quantitative (involving the mean size or timing of activity of individual puffs) and qualitative. The pattern of activity of 64% of the puffs is the same in the two strains, 12% show strain differences in puff size and 19% in the time of their activity. One puff (64C) is active only in one of the strains (vg6). In genetic experiments this puff segregates normally and the puff locus has been mapped genetically to a site coincident with, or at least very close to, the cytogenetic position of the puff. In heterozygotes the puff is homozygous only when the maternal and paternal homologues are synapsed. When the homologues are asynapsed only the homologue from the vg6 parent is puffed at 64C. With the exeption of some strains closely related to vg6 no other strain of D. melanogaster has been found to possess puffing activity at 64C. In vg6/In(3LR)C165 heterozygotes 64C forms a heterozygous puff even when the homologues are synapsed. In the discussion consideration is given to the various factors that control puff size.     

Patterns of puffing activity in the salivary gland chromosomes of Drosophila

Puffing patterns of chromosome arm 3 L of D. yakuba are compared with those of other members of the melanogaster species subgroup D. melanogaster and D. simulans. Several paracentric inversions on 3L have resulted in a considerable rearrangement of gene order in D. yakuba. However the basic sequence of changes in puffing activity which occurs during late larval and prepupal development is very similar to that of D. melanogaster and D. simulans. A fourth member of this species subgroup (D. teissieri) also has similar puffing patterns to those of D. melanogaster despite considerable chromosome evolution.     

Developmental puffing patterns in salivary gland chromosomes of Rhynchosciara hollaenderi

An analysis of puff formation and regression has been carried out in 3 morphologically distinct regions of the Rhynchosciara hollaenderi salivary gland during mid-larval through pupal development. Puffing differences among these 3 regions have been found and analysed for both RNA and DNA puffs. The presence of such differences suggests that the gland regions may also be functionally differentiated. — Developmentally specific sequences of puffs have been distinguished and correlated with morphological and physiological events which occur during the development of Rhynchosciara. The DNA puffs as well as the RNA puffs enlarge and regress at predictably specific developmental stages. The presence of particular puffing sequences in the late larval to pupal period has been compared with the occurrence of known changes in the developmental ecdysone titre for Rhynchosciara. Certain aspects of this developmental picture appear to fit the ecdysone-stimulated puffing model for Drosophila, but other aspects indicate that the Drosophila-based model may not be completely applicable to Rhynchosciara.     

Structure and activity of salivary gland chromosomes of Drosophila gibberosa

In Drosophila gibberosa the maximum secretory output of the salivary glands is in the prepupa rather than in the late third-instar larva. Using salivary chromosome maps provided here we have followed puff patterns from late second-instar larvae through the time of histolysis of the salivary glands 28–32 h after pupariation and find low puff activity correlated with low secretory activity throughout much of the third larval instar. Ecdysteroid-sensitive puffs were not observed at the second larval molt but do appear prior to pupariation initiating an intense cycle of gene activity. The second cycle of ecdysteroid-induced gene activity a day later, at the time of pupation, appears somewhat damped, especially for late puffs. Salivary chromosome maps provided here may also be used to identify homologous loci in fat body, Malpighian, and midgut chromosomes.     

Amino acid induced changes of puffing patterns in Chironomus salivary gland chromosomes

Effects of amino acids on puffing in salivary gland chromosomes of Chironomus thummi are described. All twenty naturally occurring amino acids except tyrosine were tested. Of these, only tryptophan and phenylalanine proved effective. Both induced puffs at the same seven loci: Ia3/4, Ie3, If4, Ig1, Ig2, IIId1 and IIId1/2. The induction is energy dependent and requires concomitant RNA synthesis. Amino acid induced puffs incorporate ³H-uridine into acid insoluble material. At least one monovalent plus one divalent cation has to be present along with the amino acid in the incubation medium for puff induction.     

Experimental puffs in salivary gland chromosomes of Drosophila hydei

Summary In Drosophila hydei abnormal puffing activities could be induced by temperature shocks and treatments with 1.2% and 1.4% KCl solutions. After temperature shocks in vivo and in vitro, a number of puffs showed a similar change in activity.Other puffs were found to show a change in activity only after a distinct treatment.Some of the puffs, specific for temperature shocks, showed a change in activity only at a distinct stage of development.In discussing the results, particular attention is paid to puffs observed in common after all treatments.Dedicated to Prof. H. Bauer on the occasion of his sixtieth birthday.     

Puffing in salivary gland chromosomes of picture-winged Hawaiian Drosophila

A portion of the X chromosome was examined for puffing activity shortly before puparium formation in several species of Hawaiian Drosophila. A large puff was induced by incubating excised salivary glands with ecdysone. In two of the seven species studied, the region in question has been moved by inversion to a new position relative to the banding sequence in the other species, but the reaction to ecdysone remained unchanged. Another puff, not affected by short term incubations with ecdysone, displayed different degrees of activity in some homosequential species, affording a cytological means for distinguishing these species.     

Nucleolus-organizing regions in salivary gland chromosomes of Drosophila melanogaster

Summary The nucleolus of the salivary gland nucleus of Drosophila melanogaster is formed by nucleolus-organizing regions which exist in the heterochromatin of the sex chromosomes. This interpretation is supported by the discovery of a series of induced chromosomal alterations involving transfer of nucleolus-forming regions to euchromatic sections of the chromosomes.     

Developmental puffing activity in the salivary gland and Malpighian tubule chromosomes ofAcricotopus lucidus (Diptera,Chironomidae)

A detailed map of the salivary gland chromosomes ofAcricotopus lucidus is presented. Differences in puffing and developmental Puffing sequences of the three salivary gland lobes were investigated from mid fourth larval instar to pupation and compared with the puffing pattern of the Malpighian tubules. The intraglandular differentiation is quite extensive; the differences in the pattern of gene activity between the anterior lobe and the main and side lobes are as great as between the salivary gland and the Malpighian tubules. In the main and side lobes all developmental puffing changes proceed synchronously whereas in the anterior lobe both asynchronous and synchronous changes occur. In the anterior lobe the asynchronous regression of BR 3 and BR 4 is followed by a characteristic sequence of activation and inactivation of puffs.     

Patterns of puffing activity and chromosomal polymorphism in Drosophila subobscura

Summary 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.Publication No. 109, Departamento de Genética, Universidad de Valencia, Spain