Behavior of polytene chromosomes of rhynchosciara angelae at different stages of larval development

Breuer, M. E.; Pavan, C.

doi:10.1007/bf00329733

Cited by 291 publications

(87 citation statements)

References 18 publications

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“…Much of the recent interest in the metabolic activity of DNA has centered in studies on the giant polytene chromosomes of Dipteran larvae (5,10,40,42). Certain bands on these chromosomes show a disproportionate local increase in DNA content at the time of "puffing" or Balbiani ring formation.…”

Section: Resultsmentioning

confidence: 99%

Is there "Metabolic" DNA in the Mouse Seminal Vesicle?

Gall

Johnson

1960

The Journal of Cell Biology

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This study was designed to answer the question: Is H3-thymidine uptake by nuclei of the mouse seminal vesicle evidence for DNA synthesis and mitosis, or does it signify some "metabolic" function of DNA unrelated to chromosome duplication?Mice were given an intraperitoneal injection of H3-thymidine. Six hours later Feulgen squashes of the seminal vesicle epithelium were made and covered with autoradiographie stripping film. The silver grains above labeled nuclei were counted, and the Feulgen dye contents of these same nuclei were determined photometrically after removal of the grains from the emulsion. Unlabeled nuclei were also measured.The dye contents of non-radioactive nuclei form a unimodal distribution, indicating that polyploidy is absent from this tissue. The radioactive nuclei fall into two groups. In the first, the average dye content is the same as that of the cold nuclei (2C). In the second, the values range from 2C to 4C.In the 2C to 4C group the grain count is proportional to the dye content, showing that incorporation is correlated with synthesis.The radioactive 2C nuclei arose by mitosis during the course of the experiment. This is shown by the following facts: (1) They frequently occur in pairs. (2) They average smaller than unlabeled 2C nuclei. (3) Their average grain count is approximately half that of the 4C nuclei. (4) Labeled division figures are found. (5) A mitotic rate estimated from the number of labeled 2C nuclei accords reasonably well with one based on the number of observed mitoses.Since the incorporation of thymidine accompanies DNA synthesis and precedes mitosis, there is no reason to postulate a special "metabolic" DNA in this tissue.

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Section: Resultsmentioning

confidence: 99%

Is there "Metabolic" DNA in the Mouse Seminal Vesicle?

Gall

Johnson

1960

The Journal of Cell Biology

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“…The DNA body is known to be formed in contact with the sex chromosomes (Bayreuther, 1956). The finding that the nucleolus is found inside the body suggests that the chromosome region that takes part in forming the DNA body is either tile nucleolar organizing region or a chromosomal segment involving it.…”

Section: Discussionmentioning

confidence: 99%

“…This body was further studied by Gunthert (1910). In recent years, using cytochemical methods and tritium radioautography, Urbani and Russo-Caia (1964) the females, appears suddenly in the interphase of the oogonia four divisions before meiosis, and disintegrates at a given time in the development of the fly (Bayreuther, 1952(Bayreuther, , 1956Bauer, 1952). In…”

Section: Introductionmentioning

confidence: 99%

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ULTRASTRUCTURE AND CYTOCHEMISTRY OF METABOLIC DNA IN TIPULA

Lima-de-Faria

Moses

1966

The Journal of Cell Biology

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A DNA body is present in the females of the fly Tipula oleracea and is formed in contact with the sex chromosomes in the oogonial interphases. At each oogonial mitosis, the DNA body follows the chromosomes to one anaphase group and is included in one of the telophase nuclei. The body increases appreciably in size during the interphase of meiosis. All oocytes have the body, but only a few nurse cells possess it. The DNA body synthesizes its DNA at a different time than the chromosomes, as is shown by incorporation of tritiated thymidine, and contains 59 % of the DNA of the nucleus, as is disclosed by spectrophotometric measurements. At late diplotene the DNA body disintegrates, releasing its DNA into either the nucleus or the cytoplasm. When studied in the electron microscope, the DNA body appears composed of a tight mass of intertwined fibrils. Demonstration that the main mass of the body is composed of DNA is obtained from cytochemical tests which reveal that the DNA body is Feulgen positive, stains green with azure B, incorporates H3-thymidine, and after digestion with DNase is Feulgen negative. The DNA of the body is complexed with histone, like the DNA of the chromosomes, as is revealed by an intense alkaline fast green staining. Electron microscope examination of oocytes reveals that one side of the DNA body is in close contact with the nuclear envelope and that the other side possesses an outer shell composed mainly of particles 150 to 950 A in diameter. Between the outer shell and the chromosomes there is a band of low electron opacity, 4000 to 7000 A thick. In the light microscope, this light band together with the outer shell is Feulgen negative and stains violet with azure B, this is confirmation of the presence of RNA. In the oocytes the nucleoli are found inside the DNA body. These nucleoli have a nucleolonema composed mainly of particles 150 to 250 A. The nucleoli are Feulgen negative, alkaline fast green negative, stain violet with azure B, and do not stain with azure B after RNase digestion, thus confirming their RNA content. The presence of the nucleoli inside the DNA body and of a band of RNA between the body and the chromosomes is indicative of a high RNA synthetic activity. Since the DNA of the body is complexed with histone, as in the chromosomes, and the nucleoli are located inside the body, the simplest interpretation of the DNA body is that it represents hundreds of copies of the operons of the nucleolar organizing region or neighboring regions. The situation found in Tipula has several basic features in common with the polytene chromosomes of other Diptera and with the hundreds of nucleoli present in Triturus oocytes. In all three cases, genes seem to be copied hundreds of times but are kept in different types of packages. A DNA body like the one in Tipula oleracea is found in other species of Diptera and in the Coleoptera. There is no indication, from the present investigation, that the DNA body is in any way associated with a virus.

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“…The paper containing this observation (Breuer and Pavan 1955) presents the first description of developmentally controlled gene amplification in specific genomic regions undergoing puffing, later called "DNA puffs". Pavan said on several occasions that, in discussions at scientific meetings, Prof. Beermann as well as other researchers expressed their doubts about that finding.…”

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confidence: 99%

In memoriam—Crodowaldo Pavan

Gorab

2009

Chromosoma

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Behavior of polytene chromosomes of rhynchosciara angelae at different stages of larval development

Cited by 291 publications

References 18 publications

Is there "Metabolic" DNA in the Mouse Seminal Vesicle?

Is there "Metabolic" DNA in the Mouse Seminal Vesicle?

ULTRASTRUCTURE AND CYTOCHEMISTRY OF METABOLIC DNA IN TIPULA

In memoriam—Crodowaldo Pavan

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