The influence of chromatin compactness on the stoichiometry of the Feulgen-Schiff procedure studied in model films. II. Investigations on films containing condensed or swollen chicken erythrocyte nuclei.

Duijndam, W. A. L.; Duijn, P. Van

doi:10.1177/23.12.53249

Cited by 70 publications

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“…for naked DNA of 9000 per day per generation (Nakamura et al, 1998), a 2.3-fold reduction in the rate of acid depurination of chromatin compared with DNA has also been reported (Duijndam and Vanduijn, 1975). Furthermore, although the intracellular pH of anoxic cysts has been measured at 6.3 (Busa et al, 1982), the value used to predict the rate of depurination, this may not truly represent the microenvironment of the chromatin.…”

Section: Discussionmentioning

confidence: 99%

Ametabolic embryos of Artemia franciscana accumulate DNA damage during prolonged anoxia

McLennan

2009

Journal of Experimental Biology

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SUMMARYEncysted embryos of the brine shrimp Artemia franciscana are able to survive prolonged periods of anoxia even when fully hydrated. During this time there is no metabolism, raising the question of how embryos tolerate spontaneous, hydrolytic DNA damage such as depurination. When incubated at 28°C and 40°C for several weeks, hydrated anoxic embryos were found to accumulate abasic sites in their DNA with k=5.8ϫ10 -11 s -1 and 2.8ϫ10 -10 s -1 , respectively. In both cases this is about 3-fold slower than expected from published observations on purified DNA. However, purified calf thymus DNA incubated under similar anoxic conditions at pH 6.3, the intracellular pH of anoxic cysts, also depurinated more slowly than predicted (about 1.7-fold), suggesting that cysts may in fact accumulate abasic sites only slightly more slowly than purified DNA. Upon reoxygenation of cysts stored under N 2 for 30 weeks at 28°C, the number of abasic sites per 10 4 bp DNA fell from 21.1±4.0 to 9.8±2.0 by 12 h and to 6.2±2.1 by 24 h. Larvae hatched after 48 h and 72 h had only 0.59±0.17 and 0.48±0.07 abasic sites per 10 4 bp, respectively, suggesting that repair of these lesions had largely taken place before hatching commenced. Thus, unlike bacterial spores, Artemia cysts appear to have no specific protective mechanism beyond what might be afforded by chromatin structure to limit spontaneous depurination, and rely on the repair of accumulated lesions during the period between reoxygenation and hatching.

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Section: Discussionmentioning

confidence: 99%

Ametabolic embryos of Artemia franciscana accumulate DNA damage during prolonged anoxia

McLennan

2009

Journal of Experimental Biology

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“…In spermatozoa, the amount of Feulgen-positive DNA varies after they are released from the testis, and before they achieve fertilisation; the total DNA content per sperm nucleus remains stable (Esnault and Nicolle, 1976 (Loir and Lanneau, 1984), including HCI which is routinely used during the first step of the Feulgen technique. However, when protamines are highly polymerised, they make the sperm nuclei so compact that they could be considered as resistant to destructive hydrolysis and less permeable to dyes (Duijndam and Van Duijn, 1975;Esnault and Nicolle, 1976;Porcelli et al, 1979;Nicolie et al, 1986;Guraya, 1986).…”

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confidence: 99%

Distribution of DNA, nuclear micro-heterogeneities and compaction of the chromatin in rabbit epididymal spermatozoa. Ultrastructural evaluation of the Feulgen-like technique using osmium ammine

Courtens¹,

Biggiogera²,

Fakan³

1994

Reprod. Nutr. Dev.

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Summary ― An adaptation of the Feulgen procedure to visualise DNA at the ultrastructural level, using osmium ammine instead of Schiff reagent, was applied to ultrathin sections of rabbit epididymal spermatozoa, known to display increasing chromatin compaction as they progress through the epididymis. In contrast with the somatic cell nuclei of the epididymal epithelium, which display classical staining, the chromatin of spermatozoa is partly or fully destroyed during the hydrolysis step of the technique. The sperm chromatin resistance towards destruction is a function of the initial sperm nuclear compaction and of the duration of hydrolysis prior to Feulgen-like staining. For a given nucleus, the maximum staining intensity is only obtained after an optimal duration of hydrolysis. However, because of this duration and local differences in chromatin compaction, the total DNA of a section is never completely visualised.

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“…Although this possibility cannot be completely ruled out, we think it is unlikely because it is not supported by any available evidence. In particular, no known factor in the DNA structure, conformation, or compactness can account for a 2-fold difference in the Feulgen-reaction fluorescence intensity (8,(15)(16)(17). In addition, the microscopic examination of the chromatin in metacyclic trypanosomes shows no trace of pycnosis or of any other feature that could account for this difference in fluorescence.…”

Section: Resultsmentioning

confidence: 92%

Evidence for haploidy in metacyclic forms of Trypanosoma brucei.

Zampetti‐Bosseler¹,

Schweizer²,

Pays³

et al. 1986

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

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The parasitic flagellate Trypanosoma brucei undergoes a series of morphologic and metabolic changes during its passage in the digestive organs of its insect vector, a Glossina or tsetse fly. This morphogenesis ends by the differentiation, in the salivary gland of the fly, of the metacyclic form, which will be transmitted in the bloodstream of the mammalian host. On the basis of DNA microfluorometric measurements, we propose that these metacyclic trypanosomes have a haploid amount of DNA, compared to that of bloodstream forms and also of the proventricular forms, which initiate the invasion of the salivary glands. It can be inferred that trypanosomes undergo meiosis during their developmental cycle in the tsetse fly's salivary glands and syngamy shortly after cyclic transmission.During its life cycle, Trypanosoma brucei differentiates into a series of cytologically and metabolically distinct forms. The principal forms identified in the blood of the mammalian host are the slender form, which rapidly divides and can undergo antigenic variation, and the stumpy, nondividing form. After the tsetse fly has fed on blood from an infected mammalian host, the ingested trypanosomes differentiate into the procyclic and proventricular forms in the digestive tract and subsequently into the epimastigote and metacyclic forms in the salivary glands of the fly. Although many aspects of this parasitic cycle are now well documented (see ref. 1 for a recent review), the existence of a sexual cycle in trypanosomes has been and still remains an open question (2). The identification of mitosis, meiosis, and the ploidy of these parasites is not possible by direct cytogenetic analysis because their genome does not condense into defined chromosomes at any stage of the cell cycle. However, evidence based on isoenzyme studies (2, 3) and on the recent demonstration of hybrid formation between two clones of T. brucei (4) shows that genetic exchange does take place in trypanosomes. Analysis of restriction site polymorphisms (5) and direct measurements of DNA content (6) and genome complexity (7) indicate that T. brucei is diploid. Borst et al. (6) measured the nuclear DNA content of T. brucei using quantitative absorption and fluorescence cytophotometry of individual Feulgen reaction-pararosaniline-stained cells. They performed their analyses on bloodstream and procyclic culture forms and concluded that both forms have the same DNA content. However, the amount of DNA has never been measured in trypanosomes during their developmental cycle in the tsetse fly vector. Therefore, we estimated by direct microfluorometry the nuclear DNA content, after Feulgen reaction-pararosaniline staining of proventricular and metacyclic trypanosomes. These forms are found in the saliva of flies just before and after development of the parasite in the salivary glands, respectively. The quantitative cytochemical method we used is based on the observation of a linear relationship between the amount of fluorescence and the DNA content of Feulgen-stained nucl...

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The influence of chromatin compactness on the stoichiometry of the Feulgen-Schiff procedure studied in model films. II. Investigations on films containing condensed or swollen chicken erythrocyte nuclei.

Cited by 70 publications

References 0 publications

Ametabolic embryos of Artemia franciscana accumulate DNA damage during prolonged anoxia

Ametabolic embryos of Artemia franciscana accumulate DNA damage during prolonged anoxia

Distribution of DNA, nuclear micro-heterogeneities and compaction of the chromatin in rabbit epididymal spermatozoa. Ultrastructural evaluation of the Feulgen-like technique using osmium ammine

Evidence for haploidy in metacyclic forms of Trypanosoma brucei.

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