The HRAS1 gene cluster: two upstream regions recognizing transcripts and a third encoding a gene with a leucine zipper domain.

We have cloned and characterized a 55-kb region of DNA surrounding HRAS1. It contains a cluster of two, and possibly three, genes associated with CpG islands within the 32 kb immediately upstream of HRAS1. We have sequenced cDNAs representing one of these genes, provisionally designated HRC1. The locus, which is located 29 kb upstream of HRAS1, is divergently transcribed. HRC1 cDNA probe recognizes fragments on Southern blots of DNA from other vertebrate species. In human DNA, multiple homologous fragments are detected in addition to the predicted ones containing HRC1. Therefore, this locus may represent a member of an evolutionarily conserved gene family. HRC1 expression is upregulated with HRAS1 in the EJ bladder carcinoma cell line, suggesting the possibility of coordinate regulation. The deduced translational product of the longest open reading frame (1119 nucleotides, 373 amino acids) predicts a protein with regions rich in glutamine and proline and a region similar to the helix-loop-helix motif adjacent to a carboxy-terminal leucine zipper dimerization motif with four heptad repeats. Alternate splicing of terminal exons occurs, resulting in the truncation of one proline-rich domain and preservation of the leucine zipper. Thus, a biologically important region of chromosome 11p consists of a gene cluster. At least one of these genes, in addition to HRAS1, may be involved in regulation of cell growth or differentiation.     

A new histological embedding method by low-temperature polymerisation of methyl methacrylate allowing immuno- and enzyme histochemical studies on semi-thin sections of undecalcified bone marrow biopsies

Summary A new procedure of embedding in methyl methacrylate (MMA) is introduced, which enables immunostaining by preservation of cellular epitopes. This could be achieved by reduction of polymerisation temperature from ca. 60° C to 22° C within the core of tissue blocks. Reduction of the polymerisation temperature is due to destabilisation of acrylate monomer, reduction of catalyst, exclusion of molecular oxygen, chemical initiation and reduction of environmental temperature. This results in good preservation of antigens and enzymes in the haematopoietic and lymphatic tissue of bone marrow as well as lymphoid, epithelial and mesenchymal markers in other tissues, comparable to paraffin embedding. Results are demonstrated by application of monoclonal and polyclonal antibodies and by demonstration of enzyme activity conventionally used in haematology.     

Phylogeny of Greya (Lepidoptera: Prodoxidae), based on nucleotide sequence variation in mitochondrial cytochrome oxidase I and II: congruence with morphological data

The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from nucleotide sequence variation across a 765-bp region in the cytochrome oxidase I and II genes of the mitochondrial genome. Most parsimonious relationships of 25 haplotypes from 16 Greya species and two outgroup genera (Tetragma and Prodoxus) showed substantial congruence with the species relationships indicated by morphological variation. Differences between mitochondrial and morphological trees were found primarily in the positions of two species, G. variabilis and G. pectinifera, and in the branching order of the three major species groups in the genus. Conflicts between the data sets were examined by comparing levels of homoplasy in characters supporting alternative hypotheses. The phylogeny of Greya species suggests that host-plant association at the family level and larval feeding mode are conservative characters. Transition/transversion ratios estimated by reconstruction of nucleotide substitutions on the phylogeny had a range of 2.0-9.3, when different subsets of the phylogeny were used. The decline of this ratio with the increase in maximum sequence divergence among taxa indicates that transitions are masked by transversions along deeper internodes or long branches of the phylogeny. Among transitions, substitutions of A-->G and T-->C outnumbered their reciprocal substitutions by 2-6 times, presumably because of the approximately 4:1 (77%) A+T-bias in nucleotide base composition. Of all transversions, 73%-80% were A<-->T substitutions, 85% of which occurred at third positions of codons; these estimates did not decrease with an increase in maximum sequence divergence of taxa included in the analysis. The high frequency of A<-->T substitutions is either a reflection or an explanation of the 92% A+T bias at third codon positions.