Molecular characterization of β-thalassemia in Czechoslovakia

Summary We have identified different -thalassemia mutations in 93 members of 34 families of Czech or Slovakian descent using gene amplification, hybridization with specific ³²P-labeled oligonucleotide probes, sequencing of amplified DNA, and gene mapping. The GA mutation at IVS-I-1 was found in 18 families; other Mediterranean mutations were IVS-II-1 (GA), IVS-II-745 (CG), IVS-I-110 (GA), and codon 39 (CT); these were present in 9 additional families. The GT mutation at codon 121, known to cause Heinzbody -thalassemia, was present in 3 families, and the frameshift at codons 82/83 (-G), first described in the Azerbaijanian population, in 2 families. A newly discovered allele was a frameshift at codons 38/39 (-C). One -thalassemia allele was incompletely characterized. We observed in 2 families a TC mutation at position +96 UTR (untranslated region) relative to the termination codon; this mutation likely is a rare polymorphism, -Thalassemia was rare; only one person carried the -^3.7 heterozygosity, and one other had a yet to be identified -thalassemia-1, while seven had the ^{anti 3.7} triplication.     

Cation transport systems in mitochondria: Na+ and K+ uniports and exchangers

It is now well established that mitochondria contain three antiporters that transport monovalent cations. A latent, allosterically regulated K⁺/H⁺ antiport appears to serve as a cation-extruding device that helps maintain mitochondrial volume homeostasis. An apparently unregulated Na⁺/H⁺ antiport keeps matrix [Na⁺] low and the Na⁺-gradient equal to the H⁺-gradient. A Na⁺/Ca²⁺ antiport provides a Ca²⁺-extruding mechanism that permits the mitochondrion to regulate matrix [Ca²⁺] by balancing Ca²⁺ efflux against influx on the Ca²⁺-uniport. All three antiports have well-defined physiological roles and their molecular properties and regulatory features are now being determined. Mitochondria also contain monovalent cation uniports, such as the recently described ATP- and glibenclamide-sensitive K⁺ channel and ruthenium red-sensitive uniports for Na⁺ and K⁺. A physiological role of such uniports has not been established and their properties are just beginning to be defined.     

The T→C mutation at position +96 of the untranslated region 3′ to the terminating codon of the β-globin gene is a rare polymorphism that does not cause a β-thalassemia as previously ascribed

We have observed a TC mutation at position +96 of the untranslated region 3 to the terminating codon of the -globin gene in members of two Czech families and one black family. Data from initial studies suggested that this change was the cause of a -thalassemia, but continued analyses have provided convincing evidence that this mutation is a simple polymorphism.     

Recognition motifs rather than phylogenetic origin influence the ability of targeting peptides to import nuclear-encoded recombinant proteins into rice mitochondria

Mitochondria fulfil essential functions in respiration and metabolism as well as regulating stress responses and apoptosis. Most native mitochondrial proteins are encoded by nuclear genes and are imported into mitochondria via one of several receptors that recognize N-terminal signal peptides. The targeting of recombinant proteins to mitochondria therefore requires the presence of an appropriate N-terminal peptide, but little is known about mitochondrial import in monocotyledonous plants such as rice (Oryza sativa). To gain insight into this phenomenon, we targeted nuclear-encoded enhanced green fluorescent protein (eGFP) to rice mitochondria using six mitochondrial pre-sequences with diverse phylogenetic origins, and investigated their effectiveness by immunoblot analysis as well as confocal and electron microscopy. We found that the ATPA and COX4 (Saccharomyces cerevisiae), SU9 (Neurospora crassa), pFA (Arabidopsis thaliana) and OsSCSb (Oryza sativa) peptides successfully directed most of the eGFP to the mitochondria, whereas the MTS2 peptide (Nicotiana plumbaginifolia) showed little or no evidence of targeting ability even though it is a native plant sequence. Our data therefore indicate that the presence of particular recognition motifs may be required for mitochondrial targeting, whereas the phylogenetic origin of the pre-sequences probably does not play a key role in the success of mitochondrial targeting in dedifferentiated rice callus and plants.

     

Chromium and aluminum biosorption on<Emphasis Type="Italic"> Chryseomonas luteola</Emphasis> TEM05

Cr(VI) and Al(III) are environmental pollutants that are frequently encountered together in industrial wastewaters, e.g., from mining iron-steel, metal cleaning, plating, metal processing, automobile parts, and the manufacturing and dye industries. In this work, several variables that affect the capacity for chromium and aluminum biosorption by Chryseomonas luteola TEM05 were studied, particularly the effects of pH, metal concentration and contact time. Optimum adsorption pH values of Cr(VI) and Al(III) were determined as 4.0 and 5.0, respectively. The biosorption equilibrium was described by Freundlich and Langmuir adsorption isotherms. The value of Q ^o appears to be significantly higher for the Al(III) C. luteola TEM05 system. Langmuir parameters of C. luteola TEM05 also indicated a maximum adsorption capacity of 55.2 mg g^–1 for Al(III) and 3.0 mg g^–1 for Cr(VI).     

A thoracal spinal cord teratoma associated with Taussig-Bing anomaly in a newborn

BACKGROUND: Teratomas are the most common type of childhood germ cell tumor, arising in both ovary and extragonadal locations. From 40% to 50% of the extragonadal teratomas occur in the sacrococcygeal region. Teratomas in the head, neck, brain, mediastinum, abdominal, and spinal cord locations are seen less frequently. Congenital anomalies are observed up to 26% of the cases with teratoma. METHODS: A 2-day-old newborn was admitted to the hospital because of a mass in the interscapular region. She was evaluated for this and other anomalies. The mass was excised totally, and histopathologic evaluation was done. RESULTS: Histopathologic examination of the mass revealed a mature teratoma. In addition, the child had a Taussig-Bing anomaly of the heart. CONCLUSIONS: This appears to be the first report of the association between congenital thoracic spinal cord teratoma and Taussig-Bing anomaly, a specific type of transposition of the great arteries.     

Relaxation kinetics and the glassiness of proteins: the case of bovine pancreatic trypsin inhibitor

Folded proteins may be regarded as soft active matter under physiological conditions. The densely packed hydrophobic interior, the relatively molten hydrophilic exterior, and the spacer connecting these put together a large number of locally homogeneous regions. For the case of the bovine pancreatic trypsin inhibitor, with the aid of molecular dynamics simulations, we have demonstrated that the kinetics of the relaxation of the internal motions is highly concerted, manifesting the protein's heterogeneity, which may arise from variations in density, local packing, or the local energy landscape. This behavior is characterized in a stretched exponential decay described by an exponent of approximately 0.4 at physiological temperatures. Due to the trapped conformations, configurational entropy becomes smaller, and the associated stretch exponent drops to half of its value below the glass transition range. The temperature dependence of the inverse relaxation time closely follows the Vogel-Tamman-Fulcher expression when the protein is biologically active.     

Germ line insertion of mtDNA at the breakpoint junction of a reciprocal constitutional translocation

Constitutional chromosomal translocations are relatively common causes of human morbidity, yet the DNA double-strand break (DSB) repair mechanisms that generate them are incompletely understood. We cloned, sequenced and analyzed the breakpoint junctions of a familial constitutional reciprocal translocation t(9;11)(p24;q23). Within the 10-kb region flanking the breakpoints, chromosome 11 had 25% repeat elements, whereas chromosome 9 had 98% repeats, 95% of which were L1-type LINE elements. The breakpoints occurred within an L1-type repeat element at 9p24 and at the 3'-end of an Alu sequence at 11q23. At the breakpoint junction of derivative chromosome 9, we discovered an unusually large 41-bp insertion, which showed 100% identity to 12S mitochondrial DNA (mtDNA) between nucleotides 896 and 936 of the mtDNA sequence. Analysis of the human genome failed to show the preexistence of the inserted sequence at normal chromosomes 9 and 11 breakpoint junctions or elsewhere in the genome, strongly suggesting that the insertion was derived from human mtDNA and captured into the junction during the DSB repair process. To our knowledge, these findings represent the first observation of spontaneous germ line insertion of modern human mtDNA sequences and suggest that DSB repair may play a role in inter-organellar gene transfer in vivo. Our findings also provide evidence for a previously unrecognized insertional mechanism in human, by which non-mobile extra-chromosomal fragments can be inserted into the genome at DSB repair junctions.