Are there two DNA methyltransferase gene families in plant cells? A new potential methyltransferase gene isolated from an Arabidopsis thaliana genomic library.

Using the 1kb 3' terminal DNA fragment of the mouse methyltransferase cDNA as a probe and low stringent hybridisation conditions, a new potential methyltransferase (MTase) gene family was isolated from an Arabidopsis thaliana genomic DNA library. One clone (MTase-11), which gave the strongest signal at the Northern blot, was entirely sequenced (11483 bp) and further characterised. Under consideration of the likely open reading frames and our preliminary cDNA experiments we propose that the clone 11 gene encodes for an approximately 90 kD protein. As deduced form the DNA sequence this protein contains all conserved sequence motifs specific for the 5m cytosine MTases. MTase-11 gene expression was demonstrable in callus and during germination but not in one month old plants or in leaves.     

Identification of a Secreted Fatty Acid and Retinol-Binding Protein (Hp-FAR-1) from Heligmosomoides polygyrus

Hp-FAR-1 is a major, secreted antigen of the parasitic nematode Heligmosomoides polygyrus, a laboratory mouse model frequently used to study the cellular mechanisms of chronic helminth infections. The DNA encoding Hp-FAR-1 was recovered by screening a fourth larval (L(4)) H. polygyrus cDNA expression library using antibodies raised against L(4) stage excretory/secretory (E/S) proteins. Predictions of secondary structure based on the Hp-FAR-1 amino acid sequence indicated that an alpha-helix predominates in Hp-FAR-1, possibly with some coiled-coil conformation, with no beta-structure. Fluorescence-based ligand binding analysis confirmed that the recombinant Hp-FAR-1 (rHp-FAR-1) binds the fluorescent fatty acid analog 11-((5-[dimethylaminoaphthalene-1-sulfonyl)amino)undecanoic acid (DAUDA), and by competition oleic acid. RT-PCR amplification of the hp-far-1 gene indicated that the gene is transcribed in all parasitic stages of the organism's life cycle. The presence of a secreted FAR protein in the well-defined laboratory model of H. polygyrus provides an excellent model for the further study and analysis of the in vivo role of secreted FAR proteins in parasitism, and supports the mounting evidence that secreted FAR proteins play a major role in nematode parasitism.     

An IGF-I promoter polymorphism modifies the relationships between birth weight and risk factors for cardiovascular disease and diabetes at age 36

BACKGROUND: Biochemical testing for pheochromocytoma by measurement of fractionated plasma metanephrines is limited by false positive rates of up to 18% in people without known genetic predisposition to the disease. The plasma normetanephrine fraction is responsible for most false positives and plasma normetanephrine increases with age. The objective of this study was to determine if we could improve the specificity of fractionated plasma measurements, by statistically adjusting for age. METHODS: An age-adjusted metanephrine score was derived using logistic regression from 343 subjects (including 33 people with pheochromocytoma) who underwent fractionated plasma metanephrine measurements as part of investigations for suspected pheochromocytoma at Mayo Clinic Rochester (derivation set). The performance of the age-adjusted score was validated in a dataset of 158 subjects (including patients 23 with pheochromocytoma) that underwent measurements of fractionated plasma metanephrines at Mayo Clinic the following year (validation dataset). None of the participants in the validation dataset had known genetic predisposition to pheochromocytoma. RESULTS: The sensitivity of the age-adjusted metanephrine score was the same as that of traditional interpretation of fractionated plasma metanephrine measurements, yielding a sensitivity of 100% (23/23, 95% confidence interval [CI] 85.7%, 100%). However, the false positive rate with traditional interpretation of fractionated plasma metanephrine measurements was 16.3% (22/135, 95% CI, 11.0%, 23.4%) and that of the age-adjusted score was significantly lower at 3.0% (4/135, 95% CI, 1.2%, 7.4%) (p < 0.001 using McNemar's test). CONCLUSION: An adjustment for age in the interpretation of results of fractionated plasma metanephrines may significantly decrease false positives when using this test to exclude sporadic pheochromocytoma. Such improvements in false positive rate may result in savings of expenditures related to confirmatory imaging.     

Genetic affinities of inbred mouse strains of uncertain origin

Phylogenetic analyses of genetic data arising from 144 gene loci are usedto describe the interrelationships among 24 widely used inbred strains ofmice. An unordered-parsimony analysis gives a cladogram that is virtuallyidentical to the known genealogy of the mouse strains. A loss-parsimonyanalysis is used to evaluate the hypothesis that the observed patterns ofgenetic divergence among these 24 strains can be explained by thesegregation of residual heterozygosity arising from a small population ofhighly heterozygous mice. The loss-parsimony cladogram is very similar toboth the unordered-parsimony cladogram and the known genealogy of the mice.The phylogenetic analyses of these 144 loci are integrated with data on thetype and origin of the Y chromosome. Inclusion of the Y-chromosome dataprovides additional insights into the genetic composition of several of theoriginal stocks used to produce the current inbred strains of mice. Tenstrains of uncertain origin are contained in these analyses, including AKR,BUB, CE, I, NZB, P, RF, SJL, ST, and SWR. SJL is hypothesized to have beenderived from the same Swiss albino stock previously used to produce SWR.The BUB strain appears to have had a complex origin and shows closestgenetic similarity to SWR and ST. AKR and RF are shown to be closelyrelated, while the I strain shows greatest genetic similarity to DBA/2 forthe 144 loci. However, I and DBA possess different types of Y chromosome.The NZB strain shows genetic similarity to several stocks of both U.S. andEuropean origins. The power of the genetic data used in these analysesreiterates that inbred strains of mice can be a valuable paradigm forstudies in evolutionary biology.     

Isolation and some properties of two extracellular β-glucosidases from Trichosporon adeninovorans

The yeast Trichosporon adeninovorans secretes two multiple forms of β-glucosidase at a high rate if grown in a medium containing cellobiose. Following mutagenesis a mutant strain resistant to 2-deoxy-D-glucose was selected. This strain produced more β-glucosidase activity and had acquired a strong resistance against repression by glucose. The β-glucosidases were separated one from each other by chromatography on hydroxylapatite and by gel filtration. Both enzymes have similar properties. The optimal temperature for their activity was 60 to 63°C and the enzymes displayed highest activity at pH of 4.5. The molecular weight of β-glucosidase I was found to be 570,000 and that for β-glucosidase II was 525,000. The K_m value for cellobiose was determined to be 4.1 mM for β-glucosidase I and 3.0 mM for β-glucosidase II.