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  • 1
    Electronic Resource
    Electronic Resource
    Patterns of protein synthesis in salivary glands ofDrosophila melanogaster during larval and prepupal development (1981)
    Springer
    Development genes and evolution 190 (1981), S. 351-357 
    Details
    ISSN: 1432-041X
    Keywords: Salivary gland ; Protein synthesis ; Larval development ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Patterns of protein synthesis in the salivary glands ofDrosophila melanogaster have been studied throughout late larval and prepupal development by pulse labelling the tissues with35S-methionine. Specific changes to the pattern of proteins synthesized during development are found and the significance of these changes is discussed in view of the known changes in gene (puffing) activity which occur at the same times. We review the problem of salivary gland function in “prepupal”Drosophila.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00863272
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  • 2
    Electronic Resource
    Electronic Resource
    Puffs and salivary gland function: The fine structure of the larval and prepupal salivary glands ofDrosophila melanogaster (1972)
    Springer
    Development genes and evolution 169 (1972), S. 216-238 
    Details
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The salivary glands ofDrosophila melanogaster have been examined by electron microscopy for fine structural alterations occurring during larval and prepupal stages. The changes observed in the glands have been correlated with the puffing patterns of the polytene chromosomes at corresponding stages. In early third instar larvae, the lumen of the salivary gland appears empty, and no signs of secretory activity are visible in the glandular cytoplasm. From puff stages 1 to 6 the endoplasmic reticulum becomes reorganized and increases in volume. Electron dense material appears within its cisternae and subsequently within the Golgi saccules. Dense secretory granules then appear to be elaborated from the Golgi by terminal budding; these granules represent the ‘glue’ for adhering the pupa to its substrate, and gradually increase in size and complexity. By puff stage 6 their contents have been liberated into the glandular lumen. Following puparium formation, those granules which are not extruded coalesce to form larger granules. Other dense bodies and autophagic vacuoles, considered to be lysosomes, appear, and the ‘surplus’ secretory granules begin to display myelination at their peripheries; ultimately they are reduced to dense residual bodies. At puparium formation, the lumen is depleted of the glue and contains flocculent material. Histolysis commences after puff stage 11, and the cytoplasm becomes vacuolated and opaque; the nucleus becomes reduced in volume and crenated in outline. Nuclear blebbing occurs after puff stage 12, and material seemingly moves from the nucleus into the cytoplasm; the glandular lumen now becomes empty. An attempt has been made to ascertain how the chromosomal puffing activity relates to these cytoplasmic developments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582554
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  • 3
    Electronic Resource
    Electronic Resource
    Ecdysone induction of puffing activity in salivary glands ofDrosophila melanogaster grown in adult abdomens (1973)
    Springer
    Development genes and evolution 172 (1973), S. 166-170 
    Details
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00576940
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  • 4
    Electronic Resource
    Electronic Resource
    Patterns of puffing activity in the salivary gland chromosomes of Drosophila (1967)
    Springer
    Chromosoma 21 (1967), S. 398-428 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336950
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  • 5
    Electronic Resource
    Electronic Resource
    Patterns of puffing activity in the salivary gland chromosomes of Drosophila (1969)
    Springer
    Chromosoma 27 (1969), S. 64-85 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326111
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  • 6
    Electronic Resource
    Electronic Resource
    Patterns of puffing activity in the salivary gland chromosomes of Drosophila (1969)
    Springer
    Chromosoma 27 (1969), S. 47-63 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326110
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  • 7
    Electronic Resource
    Electronic Resource
    Patterns of puffing activity in the salivary gland chromosomes of Drosophila (1969)
    Springer
    Chromosoma 27 (1969), S. 156-177 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326142
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  • 8
    Electronic Resource
    Electronic Resource
    Patterns of puffing activity in the salivary gland chromosomes of Drosophila (1972)
    Springer
    Chromosoma 38 (1972), S. 255-281 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A technique for the short term organ culture of larval salivary glands of D. melanogaster is described. Cultured Puff Stage 1 glands respond to 20-OH ecdysone by initiating the cycle of puffing activity characteristic of late larval development and puparium formation. This puffing cycle involves the sequential activation of at least 125 puffs. Their response to ecdysone allows these puffs to be divided into 3 main classes: a) PS1 puffs that regress (e.g. 25AC); b) puffs activated very rapidly (within 5 min) (e.g. 23E, 74EF, 75B) and c) puffs activated only after longer periods (〉4 h) (e.g. 62E, 78D, 22C, 63E and 82F). The detailed behaviour of representatives of each class is described. These data support Clever's distinction of ‘early’ and ‘late’ ecdysone responsive sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290925
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  • 9
    Electronic Resource
    Electronic Resource
    Relationship between relative dry mass and average band width in regions of polytene chromosomes of Drosophila (1980)
    Springer
    Chromosoma 76 (1980), S. 175-189 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Whole-mounted polytene chromosomes from Drosophila melanogaster were prepared for high-voltage electron microscopy. Relative dry mass of chromosome regions was estimated by densitometry of electron microscopic negatives. Comparison of dry mass of regions of the male X chromosome with that of regions of associated autosomes established that dry mass values are proportional to DNA content. Relative dry mass values of regions of polytene chromosomes from salivary glands, fat body, and malpighian tubules were correlated with the average diameter of bands in these regions: as mass doubled, band width increased by a factor of approximately √2. To provide a standard for estimating absolute levels of polyteny, band widths were measured for chromosomes representing one major polytene class, 256n. These chromosomes were observed to have an average band width of 0.9 μm — These observations provide limits to models of chromatin organization in bands. For each chromatid, this area can accommodate up to five chromatin fibers of 250 Å diameter. This value may represent the extent of folding of a chromatin fiber in an average band. Alternatively, a chromatin fiber of higher-order structure could have a maximum diameter of 560 Å in an average band.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293416
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  • 10
    Electronic Resource
    Electronic Resource
    Patterns of puffing activity in the salivary gland chromosomes of Drosophila (1978)
    Springer
    Chromosoma 68 (1978), S. 195-203 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335416
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