Chromosomen-Aktivit�t und biochemische Zelldifferenzierung in den Speicheldr�sen von Camptochironomus

Grossbach, Ulrich

doi:10.1007/bf00331528

Cited by 164 publications

(35 citation statements)

References 74 publications

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“…Larvae of several Chironomus species produce a salivary secretion which, according to its properties (2), fits the silk definition given by Rudall and Kenchington (3) . Formation of Diptera salivary secretion has been investigated in some species of Chironomus (4,5,6) .…”

Section: Introductionsupporting

confidence: 60%

FORMATION OF SALIVARY SECRETION IN RHYNCHOSCIARA AMERICANA

Bianchi

Terra

Lara

1973

The Journal of Cell Biology

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Section: Introductionsupporting

confidence: 60%

FORMATION OF SALIVARY SECRETION IN RHYNCHOSCIARA AMERICANA

Bianchi

Terra

Lara

1973

The Journal of Cell Biology

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“…The best explanation for the present results is that Balbiani ring 2 RNA is released into nuclear sap and, after some delay, released into cytoplasm, without being measurably reduced in molecular size. Such an interpretation is supported from earlier studies (19,20) (21,22). As the salivary protein synthesis in these cells comprise more than 80% of total protein synthesis (23), it can be anticipated that the corresponding messenger RNAs are major nonribosomal, high molecular weight RNA species.…”

Section: Methodsmentioning

confidence: 64%

Evidence for Transport of 75S RNA from a Discrete Chromosome Region via Nuclear Sap to Cytoplasm in Chironomus tentans

Daneholt

Hosick

1973

Proc. Natl. Acad. Sci. U.S.A.

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Salivary glands of the dipteran Chironomus tentans were exposed to tritiated pyrimidines for different time periods either in vitro or in vivo. Nonribosomal, high molecular weight RNA molecules of very different sizes (15-100 S) were labeled on chromosomes I-III, while only one main species, 75S RNA, was recorded in Balbiani ring 2, a giant chromosome puff on chromosome IV. 75S RNA was present as a prominent fraction in nuclear sap, but not in cytoplasm, after 90 min of incubation in vitro. During the ensuing 90 min, 75S RNA also appeared in cytoplasm. After 1 week of labeling in vivo, radioactive 75S RNA accumulated heavily in cytoplasm. Absorbance measurements showed that 75S RNA constituted as much as 1.5% of the total salivary-gland RNA. The half-life of 75S RNA was estimated to exceed 35 hr.Available data on the intracellular distribution and metabolic stability of nonribosomal, high molecular weight RNA from Balbiani ring 2 and chromosomes I-III indicate that most of the cytoplasmic 75S RNA is transcribed in the Balbiani ring 2 region of chromosome IV. 75S RNA molecules are, therefore, likely to be transferred from Balbiani ring 2, via nuclear sap, to cytoplasm without being measurably reduced in molecular size.One important step in gene expression of eukaryotic cells is the transfer of genetic information from nuclear DNA to polysomes in cytoplasm. Available data strongly indicate that this information transfer is accomplished by RNA, but the details of the process are far from clear (1). Although different defined messenger RNA species have been demonstrated in cytoplasm (2-5), it has been more difficult to identify the individual corresponding precursors in the nucleus. The main reason for this failure is that the nonribosomal, high molecular weight RNA of the nucleus is a complex mixture of molecules, with concomitant identification problems. In transformed cells, it is feasible to select for one type of RNA, the virusspecific RNA, and thus simplify the analysis (6-8). Another approach is to extensively fractionate the nucleus in order to obtain defined, nonribosomal, high molecular weight RNA species. When such a procedure was applied recently to salivary gland cells of the midge Chironomus tentans, a defined RNA species (75S RNA) was recorded in a restricted chromosome region (9). The present investigation shows that it is possible to follow the migration of that particular RNA species from its site of synthesis via nuclear sap to cytoplasm. Proc. Nat. Acad. Sci. USA 70 (1973) containing labeled, ethanol-soluble substances that would disturb the radioactivity pattern unless extracted), each sample was treated with 100 Al of SDS-Pronase solution.RNA was then precipitated overnight at -20°after 10 Al of 1 M NaCl and 250 ,l of 100% ethanol had been added. Electrophoresis. The technique with agarose gel slabs has been described in detail (13). 1% Agarose gels were prepared in 0.02 M Tris -HCl (pH 8.0)-2 mg/ml of SDS-0.02 M NaCl-2 mM EDTA. After completion of electrophoresis, the gel was cut in...

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“…The concentration of 18S RNA on the chromosome containing the Balbiani rings may have further functional significance, since the Balbiani rings seem to be the carriers for the genetic information for the salivary polypeptides, the main synthetic products of the gland (Beermann, 1966 ;Grossbach, 1969) . A similar distribution was found for 23S RNA but not for 30S RNA (unpublished data) .…”

Section: Discussionmentioning

confidence: 99%

NUCLEOLAR-DERIVED RIBONUCLEIC ACID IN CHROMOSOMES, NUCLEAR SAP, AND CYTOPLASM OF CHIRONOMUS TENTANS SALIVARY GLAND CELLS

Ringborg

Rydlander

1971

The Journal of Cell Biology

104

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The distribution of monodisperse high molecular weight RNA (38, 30, 28, 23, and 18S RNA) was studied in the salivary gland cells of Chironomus tentans. RNA labeled in vitro and in vivo with tritiated cytidine and uridine was isolated from microdissected nucleoli, chromosomes, nuclear sap, and cytoplasm and analyzed by electrophoresis on agarose-acrylamide composite gels . As shown earlier, the nucleoli contain labeled 38, 30, and 23S RNA . In the chromosomes, labeled 18S RNA was found in addition to the 30 and 23S RNA previously reported . The nuclear sap contains labeled 30 and 18S RNA, and the cytoplasm labeled 28 and 18S RNA . On the basis of the present and earlier analyses, it was concluded that the chromosomal monodisperse high molecular weight RNA fractions (a) show a genuine chromosomal localization and are not due to unspecific contamination, (b) are not artefacts caused by in vitro conditions, but are present also in vivo, and (c) are very likely related to nucleolar and cytoplasmic (pre)ribosomal RNA . The 30 and 23S RNA components are likely to be precursors to 28 and 18S ribosomal RNA . The order of appearance of the monodisperse high molecular weight RNA fractions in the nucleus is in turn and order : (a) nucleolus, (b) chromosomes, and (c) nuclear sap . Since both 23 and 18S RNA are present in the chromosomes, the conversion to 18S RNA may take place there . On the other hand, 30S RNA is only found in the nucleus while 28S RNA can only be detected in the cytoplasm, suggesting that this conversion takes place in connection with the exit of the molecule from the nucleus .

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Chromosomen-Aktivit�t und biochemische Zelldifferenzierung in den Speicheldr�sen von Camptochironomus

Cited by 164 publications

References 74 publications

FORMATION OF SALIVARY SECRETION IN RHYNCHOSCIARA AMERICANA

FORMATION OF SALIVARY SECRETION IN RHYNCHOSCIARA AMERICANA

Evidence for Transport of 75S RNA from a Discrete Chromosome Region via Nuclear Sap to Cytoplasm in Chironomus tentans

NUCLEOLAR-DERIVED RIBONUCLEIC ACID IN CHROMOSOMES, NUCLEAR SAP, AND CYTOPLASM OF CHIRONOMUS TENTANS SALIVARY GLAND CELLS

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