Monolayer versus aggregate balance in survival process for EGF-induced apoptosis in A431 carcinoma cells: Implication of ROS-P38 MAPK-integrin alpha2beta1 pathway.

A431 cells escape EGF-induced apoptosis by forming cell aggregates. We show that these clusters migrate and merge with neighboring ones, resulting in larger structures composed of a multilayer central (3D) population surrounded by a cell monolayer (2D). We found that after 48 hr of 10 nM EGF treatment, 3D structure formation correlates with alpha2beta1 integrin upregulation.

Loop formation and synaptic adjustment in a human male heterozygous for two pericentric inversions.

Pachytene analysis was undertaken in an infertile male heterozygous for two pericentric inversions of chromosomes 1 and 9. The synaptic behaviour of the bivalent 1 inversion was the most informative. Analysis of the chromomere pattern combined with centromeric heterochromatin staining allowed precise description of synaptic initiation and extension leading to the homosynapsed loop.

Complete pachytene chromomere karyotypes of human spermatocyte bivalents.

Well-spread human pachytene spermatocyte bivalents were obtained allowing specific identification of each bivalent within its total complement according to its chromomere sequence combined with further staining of its centromeric heterochromatin. The total number of chromomeres was found to be related to the degree of bivalent contraction: 396 in condensed bivalents and 511 in decondensed bivalents. A striking correspondence between chromomeres and mitotic G-bands was observed; on account of the variability of bivalent contraction, condensed bivalents corresponded to prometaphase somatic chromosomes and decondensed bivalents to mid/late prophase chromosomes.

Pachytene analysis of a man with a 13q;14q translocation and infertility. Behavior of the trivalent and nonrandom association with the sex vesicle.

Pachytene analysis was undertaken in a sterile 13q;14q heterozygous translocation carrier in an attempt to follow the segregational behavior of the trivalent and to evaluate the relationship of Robertsonian translocations in man to the impairment of spermatogenesis. Well-spread bivalents from pachytene nuclei were identified by their chromomere patterns. The trivalent was found always in cis configuration.

[Oocyte meiosis in a trisomy 18 fetus. Behavior of the supernumerary chromosome and identification of the 18 bivalent].

Associations of the three n degrees 18 chromosomes were studied in a trisomy 18 fetus (the chromosomal constitution of which had been identified by amniocentesis). The three classes of associations observed were those observed in other trisomic organisms:trivalent, trivalent presenting an important asynaptic region, and bivalent accompanied by a univalent. In addition, the sequence was established of chromomeres, the number of which varied from 18 to 23 depending on the degree of chromosome contraction.