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Biomedical subjects

W Nagl

Publications and source records attributed to W Nagl.

At least 37 records · Page 2Linked to original sources
PubMed1980

Regeneration of secretory epithelium in the human endocervix.

Biopsies of hum endocervix were obtained from healthy women at day 5, 15, and 25 of the menstrual cycle, and immediately incubated with 3H-thymidine in a culture medium for 1 to 2 h. A few labelled nuclei were found in thick, semi-thin, and ultra-thin sections and indicated that gland cells of the columnar epithelium of the endocervix were capable of DNA synthesis and hence mitosis, independent of the menstrual cycle. As basal or "reserve" cells were less frequently labelled than differentiated epithelial cells, the findings suggested renewal of the secretory epithelium of the endocervix without cell replacement by basal or "reserve" cells. We discuss the implications of the results for the understanding of normal and neoplastic regeneration and for the treatment of cancer.

Adult↗
PubMed1980

"Arabidobrassica": Evidence for intergeneric somatic hybrid nature from electron microscopic morphometry of chromatin.

The new method of species and hybrid characterization and determination by quantitative morphometry of chromatin texture in ultra-thin sections of nuclei was applied to the somatic hybrid "Arabidobrassica" and its parents, Arabidopsis thaliana and Brassica campestris. The somatic hybrid exhibits the average amount of condensed chromatin, if compared to the proportion of condensed chromatin in nuclei of the parent species. This result corresponds to similar findings in natural allopolyploids and is consistent with the assumption that "Arabidobrassica" is a true intergeneric hybrid.

Brassica↗
PubMed1979

Transitory increase in chromosomal DNA (Fleulgen) during floral differentiation in Rhoeo discolor.

Scanning cytophotometric measurements on 3200 telophase and 1700 interphase nuclei (Feulgen-stained) in vegetative and reproductive buds of Rhoeo discolor revealed a transitory increase in staining intensity in more than half of the cells in early differentiating floral buds. The differences between the vegetative and floral nuclei are significant at the 0.001 level of probability and highly reproducible, independent of the type of hydrolysis used. We suggest that the different Feulgen extinction values reflect different nuclear DNA amounts, because methodical errors can fairly be excluded. The occurrence of an extra DNA (control DNA) of the kind of the floral DNA' detected by Wardell and Skoog (1973) and Wardell (1976) in tobacco is discussed.

Chromosomes↗
PubMed1978

Short duration of the mitotic and endomitotic cell cycle in the heterochromatin-rich monocot Allium carinatum.

Fraction labeled mitoses curves and caffeine-induced binucleate cell populations, respectively, were used to determine the duration of the mitotic and endomitotic cycle in roots of Allium carinatum, a leak with a 2C DNA content of 22.4 pg and a high proportion of heterochromatin. The mitotic cycle lasts, on an average, 8.1 h, the endomitotic one 7.5 h. These relatively short times (with respect to the nuclear DNA content) are discussed in the view of a possible role of heterochromatin in shortening cell cycle duration and possible advantage of the endomitotic cycle for rapid cell and tissue growth.

Caffeine↗
PubMed1978

Electron microscopic observations of a possible tubulin synthesis-polymerization complex in oocytes of a pond-skater.

Maturing oocytes of Gerris najas display, in ultrathin sections, protein fibrils extending from ribosomes, which are often arranged on ring-like cisternae of rough endoplasmic reticulum. In some cases, the fibrils apparently continue into typical microtubules. The possibility is discussed that the huge amount of microtubules of the egg cell is synthesized and polymerized in the form of specific ribosome-tubulin-filament-microtubule complexes.

Animals↗
PubMed1976

Effects of phytohormones on thermal denaturation profiles of Cymbidium DNA: indication of differential DNA replication.

Protocorm pieces of the orchid Cymbidium were aseptically cultured either without phytohormones, or with one of the growth promoting substances, auxin cytokinin, and gibberellin. The derivative melting profiles of the extracted DNA's differ from each other with respect to the size of various AT- and GC- rich fractions. Evidence has been obtained for the increase of the more AT--rich fractions in auxin-treated cultures, while gibberellin stimulated the expansion of the GC-rich fractions. These results are consistent with earlier cytological and cytochemical findings and indicate the involvement of hormone-controlled differential DNA replication in the development of Cymbidium protocorms in vitro.

Cells, Cultured↗
PubMed1976

Electron microscopic study of the differentiation and development of trophocytes and oocytes in Gerris najas (Heteroptera).

The differentiation of oogonia and oocytes, and of trophocytes, from undifferentiated germ line cells has been studied in Gerris najas, a pond skater, from the fourth instar to the adult animal. For the first time criteria have been obtained which allow the distinction between poorly differentiated early oogonia and nurse cells. The most important criteria are the size, shape, and structure of nuclei and mucleoli. This is consistent with the different function of these cell types, which is primarily a different nuclear function: meiosis in the oocytes, and RNA synthesis to support the trophic core and the oocytes in the trophocytes.

Animals↗
PubMed1975

An A + T-rich satelitte DNA in a monocotyledonous plant, Cymbidium.

The DNA of aseptically grown protocorms of a Cymbidium hybrid and in vitro developed leaves, as well as DNA of leaves and flower buds of Cymbidium ceres from the greenhouse, was analysed by analytical ultracentrifugation and thermal denaturation. Upon ultracentrifugation a satellite DNA with a buoyant density of 1.682 g/cm-3 appears as a shoulder on the main band (density 1.694 g/cm-3). Thermal denaturation reveals an inhomogeneous main peak with the major component melting at 84 degrees C and a separate peak melting at 75 degrees C. This is the first demonstration of a satellite DNA in a monocot, and one of the rare examples of a major A + T-rich DNA fraction in a plant.

Adenine↗