Comptes rendus de l'Academie des sciences. Serie III, Sciences de la vie最新文献

Many proteases play a crucial role in the Plasmodium intraerythrocytic life cycle. Spectrin depletion, one of the major events involved in parasite release from the red blood cell, results from proteolytic activities associated with the presence of the intracellular parasite. Here, we describe a new acidic proteolytic activity from Plasmodium falciparum, whose target is the alpha-subunit of human spectrin. Immunoblotting experiments with antibodies specific for the tryptic peptides of the alpha-chain and in vitro proteolysis tests on recombinant peptides from different regions of the spectrin alpha subunit demonstrated that cleavage sites for the parasite proteolytic activity were localized within the SH3 motif of the alpha-chain sequence. Remarkably, this Plasmodium protease activity on spectrin SH3 substrate was unable to cleave the SH3 from fodrin, a non-erythroid spectrin.

We have studied the role of 2 exogenous cytokines, the TGF beta 1 and the VEGF, on the in vitro angiogenesis process. Endothelial cells were plated on fibrin matrices either with 2% or with 10% human serum in 199 medium. Forty-eight hours later, with 10% human serum, the capillary-like network index (the percentage of the culture area covered by the capillary network) was about 50%. Under these culture conditions, when TGF-beta 1 or VEGF were added, the capillary-like network index augmented and was nearing 75%. When the index is high, using confocal microscopy, we show that hollow capillaries are formed. Moreover, the addition of VEGF increased the kinetics of the capillary-like network formation. With 2% human serum, 48 h after seeding the capillary-like network index was about 75%. In this case, the addition of TGF-beta 1 decreased the network index, whereas the addition of VEGF increased the kinetics of its formation. These in vitro angiogenesis experiments show that the serological factors underline the 2 antagonist effects of TGF-beta 1, but have no detectable effects on the activator effects on the VEGF.

This study focuses on the use of hematoxylin-eosin staining plus fluorescence microscopy for the investigation of elastic fibers in some elastic cartilages. We have observed that elastic fibers are consistently imaged by the proposed procedure and the resolution attained is similar to that obtained with the classical Weigert's fuchsin-resorcin. The results also demonstrate that elastin autofluorescence gives little or no contribution to the final fluorescence and that the use of the confocal laser scanning microscope adds to the resolution, permits the use of thicker sections and reveals of minute structural at features. We conclude that this is a relevant tool in elastin research.

Menopause, conventionally defined as the permanent cessation of menstruation as a result of loss of ovarian follicular activity, is biologically expressed by the collapse of plasma estradiol levels and increased plasma levels of the gonadotrophins FSH (follicle stimulating hormone) and LH (luteinizing hormone). At present, estimation of the ovarian follicle reserve is based on endocrine capacity tests of the ovaries, with increased FSH representing the first sign of exocrine ovarian failure. We report the case of one of our amenorrhoeic patients after chemotherapy, total body radiation and allogenic bone marrow transplantation for acute immunoblastic leukaemia. This patient was included in an in vitro fertilization with oocyte donation (IVF-OD) programme for iatrogenic premature ovarian failure with increased FSH levels. Instead of high levels of gonadotrophins, this young woman recovered spontaneous follicular development, benefited from standard IVF with her own oocytes and brought a twin pregnancy to term. This observation shows that a high FSH level is not a definitive prediction of ovarian exocrine capacity. In young women of child-bearing age such as these wanting a child and showing signs of endogenous estrogen impregnation, evaluation of the existence and quality of follicular development is an important factor.

Hereditary spherocytosis (HS) is an inherited hemolytic anemia characterized by the presence of dense spherocytic red cells. In HS patients, red cell membrane protein gel electrophoresis has identified different subsets of abnormalities: isolated spectrin deficiency, combined spectrin and ankyrin deficiency, band 3 deficiency. To direct the search for the molecular defect in 9 families with dominant HS, we developed microsatellite markers specific for the membrane protein encoding genes possibly involved in HS (alpha- and beta-spectrin, ankyrin and band 3 genes) and genotyped each family. In 5 families with isolated spectrin deficiency, the beta-spectrin gene was designated as candidate. In one family with combined spectrin/ankyrin deficiency, only the ankyrin gene was not excluded, whereas in the 3 HS families with band 3 deficiency, only the band 3 gene was not excluded. This work allowed development of a reliable methodology to search for candidate genes in HS and showed the frequent involvement of the beta-spectrin gene in HS with isolated spectrin deficiency.

We propose a simple, fast and inexpensive method of identification of human centromeres on metaphasic chromosomes and interphasic nuclei. This is based on in situ hybridization of labelled oligonucleotides. The efficiency of the methodology was demonstrated on cytogenetic preparations from human heteroploid and human x hamster hybrid cell lines and also on frozen tissue sections using an oligonucleotide specific for the alpha-satellite DNA of chromosome 1. Three versions of this oligonucleotide respectively labelled with 1, 4 and 10 fluorescein molecules were synthesized. The signal intensity provided by the oligonucleotide coupled with 4 fluoresceins allowed unambiguously the detection of the chromosome and the establishment of its ploidy using a classical cytogenetic microscope without the need for an amplification procedure. The use of different fluorochromes and possibly combination with an unlabelled elongation in 3' of the oligonucleotides which stabilize its hybridization, lead to a simple multicolour method. Preliminary quantification of the signals obtained by in situ hybridization of labelled oligonucleotides and comparison with those obtained by primed in situ labelling (PRINS) using the same nucleotides as primers, suggest that the elongation generated by PRINS may be very short compared with a PCR in solution. This limited efficiency of the in situ elongation may reflect the present difficulties of PRINS and DISC PCR (direct in situ single copy polymerase chain reaction) with primers specific for non-repetitive sequencies.

The adenomatous polyposis coli (APC) gene has been found to be mutated during the development of sporadic colorectal tumours as well as in familial adenomatous polyposis patients (FAP), mutations being somatic or germinal respectively. The gene product is truncated in the carboxyterminal region but the role of the APC protein in tumorigenesis is not well understood. The purpose of this review is to reassess studies on the APC protein in an attempt to understand how the loss of its functions may cause or contribute to the development of carcinomas.

Permanent focal cortical ischemia was induced in mice by electrocoagulation of the middle cerebral artery. At different time intervals after the injury, the volume of infarction was assessed together with an analysis of neuronal death. Morphological studies of ischemic brains and detection of nucleosomal DNA ladder within ipsilateral cortices might implicate a component of this neuronal loss to apoptosis as well as necrosis. Furthermore, we used the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling) procedure to detect in situ DNA fragmentation. The localization and the proportion of apoptotic cells in the ischemic mouse brain would indicate that apoptosis contributes largely to the cellular loss induced by cerebral ischemia.

This paper reports the first karyological study of a gill neoplasia in the bivalve Macoma balthica from the Bay of Gdansk (Poland). Chromosomes were studied with an air-drying technique from gill tissue. Out of 47 specimens studied, 34 showed normal cells and a variable number of mitotic metaphases with a normal diploid chromosome number of 2n = 38, 6 had hypertrophied nuclei and a high number of mitoses with 70 to 98 chromosomes, and 7 specimens showed intermediate features. The karyotype of normal metaphases included 11 metacentric, 2 submetacentric and 6 subtelocentric chromosome pairs. The karyotype of abnormal metaphases, i.e. with a high number of chromosomes, revealed chromosomal aberrations inferring neoplastic disorders such as: different number of metacentric, submetacentric, subtelocentric and telocentric chromosome pairs than in the normal karyotype, increase of chromosome pairs especially in the small and medium-sized chromosomes, irregular monosomy and occurrence of microchromosomes. According to neoplasias recorded in bivalves species, the prevalence observed in this neoplasia is relatively high. As Macoma balthica inhabits the polluted Bay of Gdansk, the effects of environmental parameters should be elucidated.

In ras-transfected NIH3T3 cells, the transcription of the Mr 34,000 beta-galactoside specific lectin galectin-3 depends on transformation phenotypes. This observation suggests that this lectin is associated with the transformation process and/or that the ras oncogene may modulate its expression; nevertheless the involvement of ras-gene product in galectin-3 gene expression still remains unclear. In the present study, we investigated the galectin-3 expression in human HOS cells transiently or stably transfected with a ras-containing vector. We observed an increase in galectin-3 mRNA and protein content in stably ras-transfected cells which had lost their anchorage dependence for growth but no increase in cells which needed anchorage for growth or in transiently ras-transfected cells. These results suggest that the galectin-3 up-regulation in ras-transfected HOS cells is the consequence of the cell transformation rather than a direct effect of the ras gene product on galectin-3 gene expression.