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M A Hulten

Publications and source records attributed to M A Hulten.

7 recordsLinked to original sources
PubMed1994

Sperm nuclear chromatin transformations in somatic cell-free extracts.

HeLa cell extracts induced decondensation of lysolecithin permeabilized Xenopus, pig, and human sperm chromatin; decondensation began almost immediately on incubation in the extract and was completed within 10-20 min. The average enlargements of human and pig sperm nuclei were 15-fold and 3-fold, respectively. The structural organization of pig and human sperm chromatin was significantly different. Decondensation was differentially inhibited by Mg++ and polyamines; inhibition was least for Xenopus and most for pig sperm nuclei. The nuclear membrane was disintegrated on chromatin dispersion, whereas the nuclei which failed to decondense exhibited distinct nuclear envelopes. The decondensing factors were stable at 65 degrees C for 15 min. The dispersed chromatin was remodelled to somatic nucleosomal structures within 60 min. The remodelled chromatin could be recondensed to chromosome-like structures, when incubated further in extracts from mitosis arrested HeLa cells.

Animals↗
PubMed1991

Chromosome in situ suppression hybridisation in clinical cytogenetics.

The use of chromosome in situ suppression hybridisation with whole chromosome libraries has previously been reported by various research laboratories to be an effective method of identifying specific human chromosomal material. As a clinical cytogenetic service laboratory we have used the technique as a complement to diagnosis by classical chromosome banding. In three examples of structural rearrangements the potential use of the 'chromosome painting' method is assessed for its ability to enhance the routine cytogenetic service currently available.

Adult↗
PubMed1989

The relationship between number of interphase nors and nor-bearing chromosomes in non-Hodgkin's lymphoma.

The ribosomal genes (located on the acrocentric chromosomes 13-15, 21-22) may be identified by their silver stained gene products, i.e. NOR related proteins. The NOR bearing chromosome activity can be observed at metaphase with the potential for all ten chromosomes to be positively stained. On the other hand, during interphase they fuse so that eventually only a single silver positive structure is seen in resting normal cells. Investigations of histopathological sections of non-Hodgkin's lymphoma (NHL) have demonstrated a correlation between the numbers of interphase NORs and the grade of tumour. There is generally a higher number of interphase in high-grade, and a lower number in low-grade tumours. This histopathological and cytogenetic study of 13 patients with NHL shows that the higher numbers of interphase NORs in the high-grade tumours is not necessarily a reflection of increased numbers of NOR-bearing chromosomes. Examples were found of high-grade neoplasms, showing the expected high numbers of interphase NORs, but not an increased number of NOR-bearing chromosomes. Conversely, some low-grade tumours, with the expected low number of interphase NORs, had increased numbers of NOR-bearing chromosomes. Our conclusion is that the interphase NOR number is related to factors other than chromosome numbers. We suggest that NOR numbers at interphase may be related to cell turnover. This is supported by previous investigations using DNA flow cytometry and the monoclonal antibody Ki67.

Chromosomes, Human↗
PubMed1987

Electron microscopic investigations of synaptonemal complexes in an infertile human male carrier of a pericentric inversion inv(1)(p32q42). Regular loop formation but defective synapsis including a possible interchromosomal effect.

Electron microscopic investigations of surface spread synaptonemal complexes in spermatocytes from a 37-year-old man ascertained for infertility detected a pericentric inv(1), and subsequent lymphocyte analysis placed the breakpoints at p32 and q42. Most spermatocytes showed a maturation arrest at mid-pachytene explaining the azoospermia. As in two other comparatively large loop-forming pericentric inversions, initiation of synapsis took place in the middle of the inverted segment. Thus there is no indication of interstitial synaptic initiation being restricted to special pairing sites along the length of the chromosome. All spermatocytes investigated at mid-pachytene showed inversion loops, none of which was fully synapsed with a specific delay in pairing of the heterochromatic block 1qh and adjacent segments. The loops were of similar size in all the cells examined and synaptic adjustment had not taken place. There was no indication of a preferential association between the inv(1) bivalent and the XY configuration, and a functional disturbance of the X seems an unlikely reason for the meiotic maturation arrest. The most likely cause may be the failure of adequate synapsis of the inverted segment and the possibly associated pairing abnormalities of other homologues, including asynapsis and/or precocious desynapsis.

Adult↗