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  • 1
    Electronic Resource
    Electronic Resource
    Transcription and weak expression of HLA-DRB6: a gene with anomalies in exon 1 and other regions. (1998)
    Springer
    Immunogenetics 48 (1998), S. 16-21 
    Details
    ISSN: 1432-1211
    Keywords: Key words HLA ; MHC ; DRB6 ; LTR ; Retrovirus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  HLA-DRB6 is one of the human major histocompatibility complex (MHC) genes present in DR1, DR2, and DR10 haplotypes (approximately 26% of individuals). It shows several anomalies in human and non-human primates, including exon 2 stop codons (non-randomly grouped between codons 74 and 94) and a promoter region, and an exon 1 coming from an inserted retrovirus. It has been shown that not only chimpanzee but also human Mhc-DRB6 lack the usual 3’ untranslated (UT) polyadenylation signal, and in the present work it was found that the human DRB6 gene coming from an HLA-DR2 haplotype is effectively transcribed after transfection in mouse L cells, and that HLA-DRB6 molecules may be expressed on the cell surface. DRB6 transcription level is remarkably lower in human than in chimpanzee. Moreover, their exons 1 (both taken from the 3’LTR region of a mammary tumor retrovirus) are also different; this shows that these viral insertions may be an important mechanism for different evolutionary changes in orthologous genes of different species. The pathways by which DRB6 molecules may be expressed on the membrane are unclear but other examples of truncated protein expression have also been described, even within the human major histocompatibility complex (i. e., in HLA-G). Finally, the presence of mature HLA-DRB6 mRNA molecules supports the notion that splicing may take place even in the absence of a canonical 3’UT polyadenylation signal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050395
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  • 2
    Electronic Resource
    Electronic Resource
    Complete cDNA sequences of the DRB6 gene from humans and chimpanzees: a possible model of a stop codon readingthrough mechanism in primates (1999)
    Springer
    Immunogenetics 49 (1999), S. 843-850 
    Details
    ISSN: 1432-1211
    Keywords: Key words DRB6 ; MHC ; Primates ; Readingthrough mechanism ; Selenocysteine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The defective major histocompatibility complex (MHC) DRB6 gene is transcribed into mRNA in human [peripheral blood lymphocytes, transfected and Epstein-Barr virus (EBV)] and chimpanzee EBV cell lines. MHC-DRB6 presents several anomalies, which include stop codons in exon 2, lack of the usual polyadenilation signal of other MHC-DRB genes, and a promoter region and exon 1 taken from a locally inserted retrovirus. The complete cDNA sequences from human DRB6*0201 and three common chimpanzee alleles (Patr-DRB6*0108, Patr-DRB6*0109, Patr-DRB6*0111) have been obtained; two exon 1-exon 2 cDNA sequences from bonobos (Papa-DRB6*0101 and Papa-DRB6*0102) are also shown. In contrast to chimpanzee DRB6 transcripts, the human ones: (1) present an exon 1-exon 2 splicing site that includes the transcription of the first 141 nucleotides of intron 1, rendering a longer exon 1, and (2) show a duplication of exon 6, which would render a longer cytoplasmic tail in a putative DRB6 protein. These two characteristics are found in all the human sequences obtained, regardless of the cellular type tested, and they are not present in any of the chimpanzee alleles reported; consequently, they are human-specific. All the alleles reported here bear stop codons in the three possible reading frames; however, a certain level of expression of DRB6 has been observed by cytofluorometry. This could be due to the presence of a selenocysteine insertion sequence (SECIS) stem-loop structure located at the 3 untranslated region of the DRB6 mRNA, which directs selenocysteine incorporation at UGA codons. DRB6 transcription and translation would be the first gene model of a readingthrough stop codon mechanism in primate MHC. It is also feasible that the DRB6 gene might generate a population of short polypeptides, bound to plasmatic membranes, having non-antigen-presenting functions or which are presented by other MHC molecules as HLA-E presents HLA-G and -B leader sequence-derived peptides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050563
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  • 3
    Electronic Resource
    Electronic Resource
    A splicing mutation, a nonsense mutation (Y167X) and two missense mutations (I159T and A209V) in Spanish patients with ornithine transcarbamylase deficiency (1995)
    Springer
    Human genetics 〈Berlin〉 96 (1995), S. 549-551 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Four novel mutations are identified in the ornithine transcarbamylase (OTC) gene, in four patients with OTC deficiency (an X-linked disorder). The mutations represent three different categories: missense (Ile159Thr and Ala209Val), nonsense (Tyr167Stop), and causing inefficient splicing (G→A in the first intronic base) with associated aberrant splicing. They are located in exons 5, and 6, and in intron 3. Two of the mutations arose de novo in the patients, and only one mutation occurs at a CpG site. The nonsense and the splicing mutation cause, respectively, lethal early onset and non-lethal, delayed early onset clinical presentations in males. Our results confirm for Spain the high genotypic heterogeneity of OTC deficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197410
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  • 4
    Electronic Resource
    Electronic Resource
    Identification of phototrophic sulfur bacteria through the analysis of lmwRNA band patterns (1998)
    Springer
    Archives of microbiology 170 (1998), S. 269-278 
    Details
    ISSN: 1432-072X
    Keywords: Key words Phototrophic sulfur bacteria ; Chromatiaceae ; Identification ; lmwRNA ; 5S RNA ; tRNA ; Taxonomic relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several phototrophic sulfur bacteria were identified preliminarily through the analysis of the low-molecular-weight RNA fraction (lmwRNA) of bacterial cells. This fraction includes the ribosomal 5S RNA and several transfer RNAs. These molecules were separated by high-resolution electrophoresis in polyacrylamide gels, and the resulting band patterns were used as fingerprints for the identification of the organisms. We examined a large number of well-characterized reference strains together with a broad range of purple sulfur bacterial isolates from freshwater and marine environments. A cluster analysis was run using the similarity matrix calculated from the band patterns. Despite the shortcomings of the method, close relatives were clustered together yielding a number of groups consistent with the phylogenetic arrangement established through the analyses of a few available 16S rRNA gene sequences. Thus, the classification obtained gives further support to rearrangement of the group as the analyses of 16S rRNA gene sequences had previously suggested. We conclude that the analysis of lmwRNA band patterns is a rapid and simple tool for grouping and preliminarily identifying new isolates of phototrophic sulfur bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050642
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  • 5
    Electronic Resource
    Electronic Resource
    Pentachlorophenol and Pentachloroanisole in Oil Samples Associated with the Toxic Oil Syndrome (1999)
    Springer
    Bulletin of environmental contamination and toxicology 62 (1999), S. 1-7 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001289900833
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  • 6
    Electronic Resource
    Electronic Resource
    Growth of calcium phosphate on phosphorylated chitin fibres (1997)
    Springer
    Journal of materials science 8 (1997), S. 407-412 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Calcium phosphate growth on chitin phosphorylated fibres was studied using scanning electron microscopy and energy dispersive X-ray analysis (SEM, EDX), micro-Fourier transform infrared spectroscopy (FTIR), and solid state magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. The C6 chemical shift positions of 13C MAS NMR in the chitin fibres phosphorylated using urea and H3PO4 are obvious indicating that phosphorylation takes place not in the C1 but in the C6 region. Micro-FTIR and 31P MAS NMR suggested that ammonium hydrogen phosphate formed during the phosphorylation procedure. Chitin fibres phosphorylated using urea and H3PO4 and then soaked in saturated Ca(OH)2 solution at ambient temperature, which lead to the formation of thin coatings formed by partial hydrolysis of the PO4 functionalities, were found to stimulate the growth of a calcium phosphate coating on their surfaces after soaking in 1.5×SBF solution for as little as one day. The thin layer after Ca(OH)2 treatment functioned as a nucleation layer for further calcium phosphate deposition after soaking in 1.5×SBF solution. EDX-measured Ca : P ratios of the coatings of Ca(OH)2-treated phosphorylated chitin in 1.5×SBF solution suggested that calcium-deficient apatite was formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018549404092
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison of different methods for the determination of the water content and the dry mass correction factor in various plant samples (1998)
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 601-604 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The water content was measured by microwave-, oven-, and freeze-drying in different vegetables like beans, corn, potato, alfalfa, garlic, and onions. Apart from beans and bean shells, all procedures resulted in similar values. Oven-drying seemed to be less suitable for beans. In samples which were in equilibrium with the laboratory environment for a longer time, the correction factor to dry mass was determined using a freeze-drying device, infrared-, microwave- and oven-drying. All the procedures yielded similar values for this factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050765
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  • 8
    Electronic Resource
    Electronic Resource
    Novel Neural Network Models for Computing Homothetic Invariances: An Image Algebra Notation (1997)
    Springer
    Journal of mathematical imaging and vision 7 (1997), S. 69-83 
    Details
    ISSN: 1573-7683
    Keywords: morphological neural networks ; image algebra ; invariant perception ; homothetical invariances perception
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper we propose a theoretical approach toinvariant perception. Invariant perception is an importantaspect in both natural and artificial perception systems, and itremains an important unsolved problem in heuristically basedpattern recognition. Our approach is based on a general theoryof neural networks and studies of invariant perception by thecortex. The neural structures that we propose uphold both thearchitecture and functionality of the cortex as currentlyunderstood. The formulation of the proposed neural structuresis in the language of image algebra, a mathematical environmentfor expressing image processing algorithms. Thus, an additionalbenefit of our study is the implication that image algebraprovides an excellent environment for expressing and developingartificial perception systems. The focus of our study is oninvariances that are expressible in terms of affinetransformations, specifically, homothetic transformations. Ourdiscussion will include both one-dimensional andtwo-dimensional signal patterns. The main contribution of thispaper is the formulation of several novel morphological neuralnetworks that compute homothetic auditory and visualinvariances. With respect to the latter, we employ the theoryand trends of currently popular artificial vision systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008218108171
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  • 9
    Electronic Resource
    Electronic Resource
    Increased rate of nondisjunction in sex cells derived from low-quality semen (1998)
    Springer
    Human genetics 〈Berlin〉 102 (1998), S. 129-137 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The relationship between chromosomal nondisjunction and semen quality was studied in two groups of males who differ highly in their semen quality: 12 individuals with low-quality semen caused by varicocele, and 8 subjects with high-quality semen, selected from sperm donors for in vitro fertilization. Chromosomal nondisjunction was inferred from the rate of disomy found in mature sperm cells. To determine the rate of disomy, we applied fluorescence in situ hybridization using satellite-specific probes for chromosomes 1, 15, 18, X and Y. In sperm cells of males with low-quality semen, the mean rate of disomy for each of the autosomes and of hetero-disomy for the sex chromosomes (XY) was significantly higher than that observed in the high-quality semen samples: more than 15-fold higher for chromosomes 1 and 15, and 7-fold higher for chromosomes 18 and XY. Yet, the homo-disomy rate for each of the sex chromosomes (XX and YY) was almost the same in both types of semen. The large discrepancy between the low- and high-quality semen in the rate of sex chromosome hetero-disomy versus the similar rate of homo-disomy strongly suggests that the abnormal chromosomal segregation in meiocytes of males with low-quality semen resulted from chromosomal nondisjunction at the first meiotic division. The results indicate that men showing poor semen quality are at an increased risk for meiotic nondisjunction, similar to women at the end of their reproductive years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004390050665
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  • 10
    Electronic Resource
    Electronic Resource
    Identification and characterization of mutations in patients with holocarboxylase synthetase deficiency (1999)
    Springer
    Human genetics 〈Berlin〉 104 (1999), S. 143-148 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Holocarboxylase synthetase deficiency (HCS) is an autosomal recessive disorder characterized by metabolic ketoacidosis, abnormal urine organic metabolites, and dermatitis. These symptoms are improved by pharmacological doses of biotin. In this study, we have analyzed seven patients with HCS deficiency found in European and Middle Eastern countries by using reverse transcription/polymerase chain reaction/single-stranded conformation polymorphism and a sequencing analysis. Although we had previously reported that two mutations were frequent in Japanese patients, no frequent mutations were found in the patients analyzed in this study. Seven novel mutations were identified in the cDNA of the patients; these included three missense mutations, two single-base deletions that resulted in a termination codon, a three-base in-frame deletion, and a 68-bp deletion. A new polymorphism C1121T was also identified in four alleles. A transient expression study demonstrated that the HCS activities of three missense mutations and one amino acid deletion were 1%–14% that of wild-type cDNA; in contrast, the activities of the two single-base deletions followed by a termination codon and Asp571Asn were nearly undetectable. These data suggest that a variety of mutations is responsible for decreasing HCS activity and that the aspartate residue at amino acid position 571 may be crucial for the catalytic activity of HCS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004390050927
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