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D R Bentley

Publications and source records attributed to D R Bentley.

84 records · Page 5Linked to original sources
PubMed1985

The structure and genetics of the C2 and factor B genes.

This review summarises our current knowledge of the genetic organisation, structure and polymorphism of the loci for the complement proteins, C2 and Factor B--class III gene products of the major histocompatibility complex. cDNA probes specific for C2 and Factor B have been used to screen cosmid libraries of human genomic DNA, and this has allowed isolation and characterisation of the corresponding genes. Southern blot analysis of the cosmid clones and of uncloned genomic DNA has shown that there are single C2 and Factor B loci that are less than 500 bp apart. Molecular mapping has revealed that the C2 gene spans approximately 18 kb of DNA. This is in marked contrast to the Factor B gene which is 6 kb in length. The entire gene structure of the Factor B gene has been determined and the interesting features of this gene which have emerged from an examination of the intron-exon boundaries are discussed. C2 and Factor B are polymorphic and structural variants have been detected by differences in charge. The degree of polymorphism at the C2 and Factor B loci has been examined by Southern blot analysis of restriction digests of genomic DNA. Three DNA polymorphisms have been identified in the C2 gene. These polymorphisms subdivide the common allelic variant of C2 (C2C) and reveal that there is much greater variability at the C2 locus than that detected by protein typing. It is suggested that these DNA polymorphisms may serve as useful markers in the genetic analysis of diseases that are related to the major histocompatibility complex.

Amino Acid Sequence↗
PubMed1984

Cloning and characterization of the complementary DNA for the B chain of normal human serum C1q.

Normal human C1q is a serum glycoprotein of 460 kDa containing 18 polypeptide chains (6A, 6B, 6C) each 226 amino acids long and each containing an N-terminal collagen-like domain and a C-terminal globular domain. Two unusual forms of C1q have been described: a genetically defective form, which has a molecular mass of approximately 160 kDa and is found in the sera of homozygotes for the defect who show a marked susceptibility to immune complex related disease; a fibroblast form, shown to be synthesized and secreted, in vitro, with a molecular mass of about 800 kDa and with chains approximately 16 kDa greater than those of normal C1q. A higher than normal molecular mass form of C1q has also been described in human colostrum and a form of C1q has been claimed to represent one of the types of Fc receptor on guinea-pig macrophages. To initiate studies, at the genomic level, on these various forms of C1q, and to investigate the possible relation between the C1q genes and the procollagen genes, the complementary DNA corresponding to the B chain of normal C1q has been cloned and characterized.

Base Sequence↗
PubMed1984

The factor B and C2 genes.

Factor B and C2, components of the complement system, are novel types of serine proteinase that are encoded by genes in the major histocompatibility complex. cDNA probes specific for these two proteins have been used to isolate cosmid clones of genomic DNA which contain the Factor B and C2 genes. Southern blot analysis of the cosmid clones and of uncloned genomic DNA has shown that there are single Factor B and C2 loci that are less than 1 kilobase apart. The Factor B gene has been further characterized by DNA sequence analysis. It is approximately 6 kilobases in length, and is split into 18 exons. The amino acid sequence of the Ba fragment contains three homologous regions which are encoded by separate exons, suggesting that they arose by DNA duplication events. In the serine proteinase domain each of the functionally important parts of the active site are encoded on separate exons. Comparison of this region of the gene with the exon organization of other serine proteinases shows a close correlation between them, but also reveals the presence of an exon in Factor B with no homologous counterpart in the other serine proteinases. The possible functional significance of the peptide encoded by this exon and the evolution of this novel serine proteinase are discussed.

Amino Acid Sequence↗
PubMed1984

Isolation of cDNA clones for human complement component C2.

Two cDNA clones for complement component C2 have been isolated from a high-complexity human liver cDNA library by using a mixture of 64 synthetic oligonucleotides as a probe. The 400-base-pair insert of pC201 codes for a region containing the active site serine residue and the secondary substrate binding pocket of the serine protease. This part of C2 is 34% homologous to the corresponding region of the related serine protease factor B and additional similarity is evident from a number of conservative amino acid replacements in this region. The insert of pC201 was used as a specific probe in RNA transfer analysis to determine the size of the C2 mRNA as approximately equal to 2.9 kilobases. Southern blot analysis of genomic DNA of unrelated individuals identified a single C2 locus and showed no cross-hybridization with the factor B locus.

Amino Acid Sequence↗
PubMed1982

Sequence of the N2 neuraminidase from influenza virus A/NT/60/68.

The complete sequence of the neuraminidase gene of influenza virus A/NT/60/68 (N2 subtype) was determined following cloning of full length complementary DNA into pBR322. Comparison of the predicted amino acid sequence with a closely related neuraminidase from A/Udorn/72 suggests that point mutations over an extensive region of the primary sequence can contribute to antigenic drift, although the region between amino acid residues 308 and 371 may be particularly significant.

Amino Acid Sequence↗
PubMed1971

Genetic control of an insect neuronal network.

Motor activity responsible for the calling song of crickets is generated by a small neuronal network whose output is genetically determined. Genes controlling certain output features are located on the X chromosome. The genetic system involved is polygenic and multichromosomal. In some patterns, genetically derived information is adequate to specify the difference of a single impulse in the output of homologous neurons from different genotypes.

Animals↗
PubMed1970

Postembryonic development of adult motor patterns in crickets: a neural analysis.

Adult crickets have stereotyped patterns of motor output which are generated by the central nervous system, and which serve as a standard against which emerging nymphal patterns can be measured. The neural circuits generating these patterns are not functional at hatching. The pattern elements appear in an ordered sequence over the course of the last four molts. The circuits are completely functional before the final molt. Circuits which might be prematurely activated are suppressed in the nymph by descending inhibition from the brain.

Action Potentials↗
PubMedDate not supplied

Direct diagnosis of carriers of Duchenne and Becker muscular dystrophy by amplification of lymphocyte RNA.

Rapid detection of deletion and duplication mutations that cause Duchenne and Becker muscular dystrophy was achieved in patients and carriers after amplification of small amounts of mRNA from peripheral blood lymphocytes. The entire coding region of the dystrophin mRNA was amplified in 10 sections by reverse transcription and nested polymerase chain reaction, and the products were directly visualised on acrylamide minigels with ethidium staining. Major structural gene mutations were identified by the appearance of a band of different size to that of the wild type. The altered band was readily detected in all patients and heterozygous relatives. This non-radioactive test of venous blood samples can be used for unambiguous and rapid identification of virtually all carriers of deletions or insertions within the dystrophin gene.

Base Sequence↗
PubMedDate not supplied

A molecular map of the human major histocompatibility complex class III region linking complement genes C4, C2 and factor B.

Four human complement genes, which have previously been mapped between HLA-D and HLA-B on chromosome 6, have now been aligned on a 98-kilobase (kb) section of the chromosome on the basis of four overlapping cosmid clones of genomic DNA. The C2 and factor B genes, less than 2 kb apart, are about 30 kb from two C4 genes separated from each other by about 10 kb.

Chromosome Mapping↗