Techniques de recherche des polymorphismes génétiques

Sequencing the human genome has allowed the discovery of millions of DNA sequence variants. Sequence variations in human DNA are mainly present asSingle Nucleotide Polymorphisms (SNPs); this common form of variation is found about once every 1,000 bases in the human genome and 1.8 million SNPs have now been identified and located. The accessibility of databases of SNPs opens the possibility of studying the influence of these polymorphisms on disease risks as well as on drug responses. Numerous approaches have been set up for the identification of SNPs. In this review we describe the main techniques used for the identification of these polymorphisms. They rely on two major consequences of sequence variations: the apparition or the disappearance of restriction enzyme sites or the alteration of DNA strand hybridization due to the presence of a mismatch. Southern blotting and restriction endonucleases have allowed the development of the technique ofrestriction fragment length polymorphisms (RFLPs), now performed on PCR products. Several other approaches such as denaturing high-performance liquid chromatography or real-time PCR can detect allele differences upon re-hybridization and heteroduplex formation. However, DNA sequencing remains the obligate step for the positive identification of known or unknown SNPs. At last, the development of high-throughput methods allows a large increase in the rate of discovery of SNPs likely.     

Sucres insaturés fluorés

Treatment of 1,2:5,6-di-O-isopropylidene-α-d-ribo- and xylo-hexofuranos-3-uloses with (difluoromethylene)triphenylphosphorane and (chlorofluoromethylene)-triphenylphosphorane gave unsaturated, ramified halogeno sugars in good yield. Treatment of the chlorofluoromethylene derivatives with lithium aluminum hydride gave stereospecifically the corresponding fluoromethylene derivatives with inversion of configuration at the double bond. The configuration was determined by ¹h- and ¹⁹F-n.m.r. spectrometry.     

Dérivés Monotritylés du D-xylose

Monotritylation of O-acetyl derivatives of D-xylopyranose and D-xylofuranose with trityl chloride in acetonitrile-pyridine gave the tri-O-acetyl derivatives of 1-,2-, 3-, and 5-O-trityl-D-xylofuranose and of 1-, 2-, 3-, and 4-O-trityl-D-xylopyranose which were required for the identification of the various monotrityl derivatives obtained in the tritylation at 50° of D-xylose with trityl chloride in pyridine or hexamethylphosphoric triamide-silver acetate.     

Techniques de préparation des microhyménoptères

Summary The author proposes to standardize the preparation technique for microhymenoptera. The insects have to be presented for identification in a dry state, mounted on a minute pin or glued on a heavy paper point (double-mounting). Preference is given to the mounting on minute pin, as this method has the advantage that a specimen pinned with a minuten may be removed from its support and each morphological detail easily observed. The minuten is fixed to a short strip of soft material such as polyporus (bracket fungus); if this is not available, stiff paper may be used. The support with the pinned specimen is then attached to a pin no. 3 (fig. 1–3). The absence of glue is advantageous, especially in subtropical countries, where the glue is generally destroyed by bacteria and fungi. When the pins are unavailable for this double-mounting technique, the author proposes to glue the thoracic pleurae of the insect to the previously folded tip of a heavy paper point (fig. 6). The material for identification may be preserved in a liquid medium (as alcohol with some drops of glycerine) after a series of individuals have been prepared according to the double-mounting technique. Also, specimens in excess may be sent dry in a plastic or glass tube between two cellucotton masses.      

Études palynologiques dans le Miocène du Cap Bon (Tunisie).Essai d'établissement d'écozones et de reconstitution paléogéographique

The palynological study of 3 borings and of an outcropin the Miocene of the Cap Bon, Langhian to Messinian (?) allowed the characterisation of 5 ecozones in this region of Tunisia and the correlation of the different sites.The inventory of about 20 000 microfossils (pollens, spores, dinoflagellates, algae and chitinous microforaminiferas) makes conspicuous the evolution of the vegetation and shows the four sites are differently evolving on a palaeogeographical point of view:

• -the drill HGA1, SSE off the actual coast, indicatesan important subsidence and here the presence of a graben; the sea sedimentation in the base becomes lagoonal, then subcontinental and there is a return of the sea in the last studied level;
• -the drill CB101, on land in the middle of the CapBon, is situated in open sea, transgressive at the base, more neritic to lagoonal or brackish at the top;
• -for the drill HW1, in front of the SE coast, we seea high sea-bed poor in sedimentation;
• -the section of Oued Khazrmia translates an emerged domain near the continental shelf. So it seems there is a gradient for subsidence and for transgression from NE to SW, obliquely with the present situation.

The palaeoclimate has always a trend to ariditymore or less important in the time, it is subtropical to warm temperate; a more humid microclimate is developing in the brackish littoral regions.The palaeogeographical evolution seems to be explained by the climatic changes and/or the eustatic variations which are of a worldwide origin or caused by tectonic in the region of the Sicilian-Tunisian strait.     

Xéroderma pigmentosum: Huit cas d'évolution différente dans deux familles

Eight cases of xeroderma pigmentosum are described-six in family B. and two in family T. The criteria used in making this diagnosis are indicated. The occurrence of epitheliomas and melanoma was observed. In family B. five of the six patients are alive at time of reporting, their ages varying from 40 to 55 years. In family T. the two affected children died at ages 8 and 14 years. The differential diagnosis between xeroderma pigmentosum and other conditions is briefly discussed.     

Biologie et politique IV. — Questions d'éthique

Within the framework of the increasing development of techniques and technology, Humankind is often considered and used as an instrument. Because power from the industry can generate bad consequences that are unforeseeable and thus out of a comprehensive control, new thoughts on Mankind and its values are needed. The moral code gives the practical distinction between good and evil. Ethics calls to a reflection from free, reasonable and responsible beings. Numerous groups of thoughts working for a progressive emergence of universally admitted ethic rules that should allow the offer of an international right of ‘Human rights’ are now available at different levels, i.e. professional, national, international. From the biomedical ethic, it appears that Human beings, considered as biological entities, have the right to live, that the embryo must not be used as an usual research material and that the diagnostic of embryos before implantation must be exceptional. Human being has a right to dignity. This means that one must not be submitted to degrading treatments (torture, slavery, …), must have access to health care, must not constitute an experimental object, the germinal cells must not be manipulated and neither his body or its constituting elements must ever be commercialised or patented. Corpses need respect and any attack to their integrity (in order to extract profits for public health, science, justice…) must be justified. A person, defined here as a self-awa-reness constructed in function of other persons, must be free (i.e. his consent is absolutely needed for a diagnostic or experimental treatment) and has economical, social and cultural rights. French laws do not permit a person to choose his death The international law progressively refines a definition of crime against humanity (ethnic extinction, torture, rape…). In the ethics for environment, the respect of men towards animals considered as individuals and species in the framework of the conservation of the nature and genetics resources, is taken into account rather than the rights of animals per se. Finally, an arsenal of agreements, directives and legislation at local, national and international levels attempts to harmonise the practices of the technoscience with the concept of long lasting development, in order to maintain the higher-order balances within ecosystems. Mankind felt itself responsible of the environment for the future generations. Nevertheless, any regulation in the matter of ethic remains a compromise within contradictory views. The only general rule for every one, remains not to harm others, and to give oneself to others. This is, for long time, the traditional basis of religious preachments, although its success remains relatively controversial.     

Les levures,dans les stations d'épuration des eaux usées

Résumé Les auteurs étudient l'influence des stations d'épuration sur la population de levures dans les eaux usées d'origine urbaine. Quantitativement, le nombre de microorganismes diminue de 90% lors du traitement. 49 espèces ont été identifiées. Les témoins de pollution d'origine humaine ont été plus particulièrement recherchés. Les auteurs indiquent les modes de détection du Candida albicans.The authors have studied the influence of sewage treatment plants over the yeast population in the waste waters coming from towns. Quantitatively, the number of microorganisms shows a 90% decrease in the process of the treatment. 49 different species have been identified. Evidence of pollution coming from human being has been particularly looked for. The authors point out the different ways of detecting the Candida albicans.     

Sur quelques propriétés physico-chimiques des protéines séparées des sérums par la méthode à l'acétone

Sans résuméCes diverses études conduisent toutes à cette conclusion que la séparation des protéines effectuée à basse température par la méthode dite à l'acétone de MM.Piettre etVila respecte l'intégrité des molécules protéiques.     

Marqueurs du tractus génital et activités glycosidasiques séminales

Seminal liquefaction corresponds to a proteolysis of glycoproteins and could also result in a lysis of linked glycans involving glycosidases. It is well known that α-1-4 glucosidase is a real epipidymal marker. The aim of this study is to point out new markers among the glycosidases and especially β-D-mannosidase, α-L-fucosidase and N-acetyl-β-D-glucosaminidase. There is no correlation between the three enzymatic activities and the sperm count. Moreover in case of azoospermia enzymatic activities were always present. The variations observed are both quantitative (β-MAN activity is significantly decreased) and qualitative (modifications of the relative proportions of the different enzymatic forms) according to the etiology of azoospermia.     

Activité cytokinine de dérivés acylés,alkylés,acyl-alkylés de l'adénine et d'isost`eres azotés de la γ,γ-diméthylallyladénine

The cytokinin activities of various 6-acylaminopurines, 6-alkylaminopurines, 6-acylamino-9-benzyl-purines as well as a series of isosteric-nitrogen derivatives of N⁶-(γ, γ-dimethylallyl)adenine (I⁶Ade) have been tested using the tobacco pith and the pea bud bioassays. The interactions between active, slightly active and inactive compounds have been studied with the last assay. Acylation decreases the biological activity; e.g., N⁶-benzoyl and N⁶-furoyladenines are less active than Na⁶-benzyladenine and kinetin. Substitution at the 9-position reduces (tobacco-pith assay) or suppresses (pea-bud assay) the phytohormonal activity of otherwise active 6-acylaminopurines. In isosteric derivatives, maximum activity occurs when the side chain has the same length as in 1⁶Ade. After the analysis of interactions between more or less active compounds, it is suggested that the differences in cytokinin activity could be related to unequal affinities for a hypothetical receptor site.     

Les échanges d'ions dans les tissus végétaux

Sans résumé