Physical and geochemical characteristics of land mud volcanoes along Colombia's Caribbean coast and their societal impacts.

The Caribbean coast is characterized by the presence of mud volcanoes, a secondary phenomenon of volcanism similar to mud diapirs for its development and evolution, but different in terms of geological features and forms. These mud volcanoes are often located close to tectonic faults and oil and gas deposits. Their geological context is dominated by the presence of clay sediments and brackish water, that favors the decomposition of organic material and the formation of methane. Mud volcanoes can thus be an important reservoir of hydrocarbons. This paper aims to fill the existing gap in the knowledge of mud volcanoes (MVs) of Colombia. We analyze the physical and geochemical characteristics of nine onshore mud volcanoes located in the Departments of Atlántico (La Laguna), Bolívar (Las Palomas, La Bonga, Santa Catalina, Yerbabuena, Clemencia, and Membrillal), Cordóba (Los Olivos), and Magdalena (Cañaveral). These structures present a kaolinitic composition, except for La Laguna mud volcano in which smectite is predominant. Apart from tectonic processes, this influences the shape and size of MVs and, also, the type and frequency of eruptions. The abundance of methane in all sites confirms the thermogenic origin of these structures. MVs are often considered landscape attractions as well as a therapeutic resources, but unfortunately they also represent a serious risk for the local communities, due to the frequent unexpected, eruptions, sometimes accompanied by the release of toxic gases or by landslides, that can damage the infrastructures and hurt the population living in the area. The MVs are classified into five vulnerability classes using a novel synthetic index which could improve the understanding of risks associated with the presence of MVs in proximity to towns and infrastructures.

A second middle eastern kindred with autosomal recessive non-syndromic hearing loss segregates DFNB9.

A second kindred has been identified which supports the previously reported location of DFNB9. Linkage has been established to markers closely linked to DFNB9 which is located on 2p22-p23. The hearing impaired individuals in this highly consanguineous kindred from Eastern Turkey have prelingual profound hearing loss which affects all frequencies. A genetic map of the 2p22-p23 region where DFNB9 resides was generated using marker genotypes available from the CEPH database. All markers were placed on this genetic map using a likelihood ratio criterion of 1000:1. This map suggests that the region for DFNB9 is less than 1.08 cM, 95% confidence interval (0-2.59 cM).

Scaffold/matrix-attached regions: topological switches with multiple regulatory functions.

The nuclear matrix or scaffold that can be prepared and investigated in vitro has an affinity for distinct topological forms of DNA and for sequences that permit the induction of such a topology by their association with a corresponding set of proteins (so-called matrix- or scaffold-attached regions, S/MARS). As a consequence, S/MARS are regarded as topological sinks that can be regulated according to activity-related requirements. Here we develop a switching model to understand the biological functions of S/MARS, which are able to augment transcriptional processes and form barriers between independently regulated domains. The current literature is screened for examples supporting such a mechanism and novel approaches are suggested for their further elucidation.

The transgeneticist's toolbox: novel methods for the targeted modification of eukaryotic genomes.

Classical techniques for gene transfer into mammalian cells involve tedious screening procedures to identify transgenic clones or animals with the appropriate level and stability of expression or with the correct developmental patterns. These first generation technologies are clearly inadequate for complex genetic strategies by which gene regulation can be studied in its entire complexity. While site-specific insertions can principally be achieved by homologous recombination or by adapting the recombination apparatus from phages or yeast, these methods usually lack the required efficiency or they perturb expression patterns by the co-insertion of prokaryotic vector parts. Virtually all of these problems can be overcome by recombinase-mediated cassette exchange (RMCE) techniques which cleanly replace a resident cassette that is flanked by two hetero-specific recombination target sites for a second cassette with the analogous design, presented on a targeting vector. After illustrating the fundamentals of site-specific recombination by selected experiments, the authors (arranged in the chronological order of their contribution) will describe their efforts to develop RMCE into a method of wide applicability. Further developments that have been initiated utilizing the particular potential of the RMCE principle will be outlined.

[Hereditary deafness in Turkey. Initial results]. / Hereditäre Schwerhörigkeit in der Türkei. Erste Ergebnisse.

The authors describe a study in progress to identify Turkish families with hereditary hearing loss and isolate possible responsible disease genes. Due to extreme genetic heterogeneity and limited audiological differentiation of hereditary hearing loss, it is necessary to identify large or small families from genetic isolates to locate loci responsible for hearing loss on a chromosome. To accomplish this goal, the medical records of 3800 children were examined at the ENT Clinic of Ege University between 1975 and 1994. All were suspected of having various hearing impairments. Additionally, students from two schools for the hearing impaired in Izmir and Eskisehir, Turkey were examined. To date, 16 families with syndromal deafness and 55 families with non-syndromal hereditary hearing loss involving two or more affected individuals have been identified and categorized according to the mode of inheritance. The majority (66%) of the non-syndromal families showed an autosomal recessive pattern, 29% an autosomal dominant inheritance and 5% an X-linked mode of inheritance. In the study presented there has been a predominance of affected males versus females and the consanguinity rate was 22%.