Das Puffmuster der Borstenapparat-Chromosomen vonSarcophaga barbata

The chromosome complement ofSarcophaga barbata polytene scutellar trichogen and tormogen cells is described and the puffing sequences of chromosome IV were analysed from day 5 to day 17 of pupariation, i. e. from the beginning up to the end of bristle and socket formation at 21°C. There are 5 normal polytene chromosomes and a complex of fibrillar and granular heterochromatin in the giant cell nuclei. It is supposed that the heterochromatic masses represent the underreplicaetd sex-chromosomes. During a 13 day period of development 105 puffs appear in the trichogen cell chromosome IV respective 102 puffs in the tormogen cell chromosome IV. The puffing patterns of these two sister cells show many similarities. However, according to the differences in development, morphology and function of bristle and socket, there are also specific differences in the puffing patterns of the trichogen and tormogen cell. Preliminary observation suggest that the hormone bursicon induces some new puffs in the tormogen cell chromosomes of freshly emerged adults.     

Localization of nuclear proteins related to high mobility group protein 14 (HMG 14) in polytene chromosomes

An antibody was raised against high mobility group nuclear protein 14 (HMG 14) from calf thymus, known to be associated with actively transcribed chromatin. By means of indirect immunofluorescence, it was shown to react with the nuclei of mouse fibroblasts and of brain cells from Xenopus and Drosophila, but not of Xenopus erythrocytes. The antibody was used to detect immunologically related proteins in giant chromosomes of the midge, Chironomus pallidivittatus. Indirect immunofluorescence with anti-HMG 14 antibody in polytene nuclei was restricted to the active puffs. Giant puffs (Balbiani rings) exhibited especially intense fluorescence in their peripheral regions. An inducible puff site, the Balbiani ring 6 locus, showed no reaction with the antibody prior to induction. When puff formation began, the chromosome site assumed a very intense fluorescence, which disappeared again when the Balbiani ring was recondensed. — Protein extracts of salivary gland nuclei were found on immunoblots to contain one major protein fraction that reacted with the anti-HMG 14 antibody. The electrophoretic mobility of this fraction was similar to that of calf thymus HMG 17. — It is concluded that actively transcribed puffs in polytene chromosomes contain HMG 14-related protein(s) that are not present in potentially active gene loci prior to induction.This paper is dedicated to Prof. Hans Bauer on the occasion of his 80th birthday.     

RNS- und Protein-Synthese in Puffs isolierter Speicheldrüsen-Chromosomen von Chironomus

Isolated salivary gland chromosomes of Chironomus tentans incubated in a simple salt or sucrose solution are able to synthesize not only RNA but also protein in their puffs. The migration of radioactively labelled material from isolated nucleoli to isolated chromosomes suggests that not all protein in the puffs is synthesized by the puffs themselves but that part of the puff protein stems from the nucleoli. It is concluded that besides bound RNA polymerase a puff contains ribosomes attached to the growing mRNA molecules.     

Polytene chromosomes and nucleic acid metabolism during macronuclear development in Euplotes

Polytene chromosomes in two species of Euplotes, E. woodruffi and E. eurystomus, have been described during the macronuclear development following conjugation. In these two species, the giant chromosomes appear briefly in the macronuclear anlagen and disappear completely later. DNA synthesis begins concomitantly with the appearance of the giant chromosomes and reaches a peak at the maximum stage of polyteny. Shortly thereafter DNA begins to break down and the breakdown products leave the macronuclear anlagen, reducing the DNA content in the anlagen to the amount present at the earlier stages of the polytene development of the chromosomes. A later phase of DNA synthesis occurs in the anlagen with the appearance of replication bands comparable to the bands which double the DNA in the somatic macronucleus. These replication bands initiate several rounds of DNA synthesis which finally lead to the development of the vegetative macronucleus. RNA synthesis occurs uniformly on the giant chromosomes and no special RNA producing puffs or other regions are noticed on them.Research supported by American Cancer Society grant E 434 to David M. Prescott and by the Deutsche Forschungsgemeinschaft to Dieter Ammermann.     

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.     

Circadian control of the cellular response to β-ecdysone in Drosophila lebanonensis

Drosophila lebanonensis displays a strict circadian rhythm with regard to the puparium formation and the occurrence of ecdysone-specific puffs in the salivary gland chromosomes. In normal development these puffs occur 3–4 hours before puparium formation. Injection of β-ecdysone at periods before ecdysone puffs are present, induces in all instances their appearance within 30 minutes, irrespective of the phase of the circadian oscillation at the time of injection. In spite of the appearance of the hormone specific puffs following β-ecdysone injection, puparium formation did not occur 3–4 hours after the puffs became active. Depending upon the time of injection within the circadian cycle, puparium formation occurred 5–6 hours after injection (when injection was performed close to a “gate” period), or occurred during the next “gate” of the circadian oscillation.     

Cytochemische Untersuchungen an Puffs isolierter Speicheldrüsen-Chromosomen von Chironomus

Enzymatic digestion experiments on unfixed isolated salivary gland chromosomes of Chironomus tentans combined with specific staining reactions reveal that puffs and Balbiani rings contain a basic protein. This basic protein in the puffs and Balbiani rings differs in most respects from chromosomal histones but shows similarities with basic structural protein of ribosomes. This finding is in agreement with the hypothesis that ribosomes participate in the build-up of puffs and Balbiani rings.     

A change in the puff spectrum during development of Drosophila virilis]

The puff spectrum has been studied in the salivary gland chromosomes of D. virilis from 48 hrs of the 3rd larval until the gland lysis. 142 puffs were observed in the D. virilis genome. Among them, 43% were observed at all developmental stages and other puffs were unstable: 47.1% appear at a certain stage and degrade or remain until the gland lysis; 9.9% are characterized by the "pulse" activity, i.e. they appear at a certain stage, degrade and reappear. The number of newly appeared puffs exceeds that of fully degraded ones, i.e. the number of puffs during the gland development until its lysis increases constantly. At the stage of puparium formation, sexual differences in the puff length were found: puffs were longer in males than in females.     

Isolation and characterization of the ecdysone receptor and its heterodimeric partner ultraspiracle through development in Sciara coprophila

Regulation of DNA replication is critical, and loss of control can lead to DNA amplification. Naturally occurring, developmentally regulated DNA amplification occurs in the DNA puffs of the late larval salivary gland giant polytene chromosomes in the fungus fly, Sciara coprophila. The steroid hormone ecdysone induces DNA amplification in Sciara, and the amplification origin of DNA puff II/9A contains a putative binding site for the ecdysone receptor (EcR). We report here the isolation, cloning, and characterizing of two ecdysone receptor isoforms in Sciara (ScEcR-A and ScEcR-B) and the heterodimeric partner, ultraspiracle (ScUSP). ScEcR-A is the predominant isoform in larval tissues and ScEcR-B in adult tissues, contrary to the pattern in Drosophila. Moreover, ScEcR-A is produced at amplification but is absent just prior. We discuss these results in relation to the model of ecdysone regulation of DNA amplification.     

Multivariate statistical analysis of the response of the cockroach giant interneuron system to wind puffs

The cockroach Periplaneta Americana responds to wind puffs by turning from the source of the wind. This turning movement is thought to be initiated by sensory responses to the wind puff occurring on filiform haircells on the cerci. The responses on the haircells initiate responses on 14 giant interneurons that rapidly transfer the information about the puff from the abdomen to the thorax and head. This response, in turn, is thought to initiate the escape response on the cockroach. In this paper a multivariate statistical analysis of the response of the 14 giant interneurons to wind puffs from a variety of angles is considered. A temporal-spatial integration model is proposed for the neural processing units acting as terminators for the giant interneurons and it is shown that using appropriate spatial integration, the cockroach can accurately estimate the direction of a wind puff on the basis of the response seen on the giant interneurons. It is also shown that with appropriate spatial integration, wind puffs from the left can be discriminated from wind puffs from the right. The right-left discrimination method is shown to be robust against the loss of any single giant interneuron. In some cases several giant interneurons can be lost without losing the right-left discrimination ability.     

The effect of prolonged exposure to heat on the activity of salivary gland polytene chromosomes]

The influence of long-term heating on the puffing activity of polytene chromosomes in the early prepupa salivary glands was investigated. The activity of puffs was estimated by two criteria: size and frequency. The rearing of insects at a temperature of 29 degrees resulted in puff changes: the activity of some puffs increased or depressed, some puffs were inhibited, other puffs were induced newly. The differential response of each chromosome was observed. A possible mechanism of the effect of heating on the puff activity of polytene chromosomes is discussed.     

The hormone ecdysone as effector of specific changes in the pattern of gene activities of Drosophila hydei

The hormone ecdysone induces a large number of changes in the puffing pattern of mid third instar larvae of Drosophila hydei. The pattern of changes occurring after experimental administration of the hormone are identical with those observed in normal development during a 6 hour period before puparium formation. After administration of the hormone a considerable number of puffs react with a change in activity within 15–20 min. During this period 3 puffs arise newly, 12 puffs show a strong increase in activity, 6 puffs show a less pronounced increase in activity and 12 puffs show a decrease in activity. At a period of 4–6 hours after administration of the hormone another 5 puffs arise newly. The effect of the hormone was identical in both in vivo and in vitro experiments. — Diameter measurements on several puffs reacting within 30 min with an increase in diameter showed that these puffs reacted simultaneously. Most of the puffs that showed a decrease in activity reacted with some delay. — A study of the effect of different hormone concentrations revealed that the kinetics of 4 puffs with respect to the relationship between concentration and puff size was identical over a range of concentrations from 33·10^–5 to 33CU/l. Three of these puffs showed a reaction with even lower concentrations. Maximum puff size is attained by all puffs at a concentration of 33·10^–4CU/l. Among the puffs studied no difference in their reaction threshold was found. — A study of the behavior of 5 puffs of the group reacting within 15–20 min and one of the group reacting after 4–6 hours in midintestine and Malpighian tubules revealed that these puffs showed the same reaction after injection of the hormone as observed in the salivary glands. — All puffs activated by administration of the hormone showed particularly strong uptake of tritiated uridine and accumulation of acidic protein. — It is concluded that the hormone ecdysone induces a pattern of changes in gene activity that is far more complex in Drosophila hydei than in Chironomus tentans.