Metaigneous rocks from Gampola and Nuwara Eliya belong to the Highland Complex of Sri Lanka. Rb-Sr and Sm-Nd age data and initial Sr and Nd isotopic ratios document several geological events. (1) Separation of crustal material began in the late Archean. (2) Partial melting of crust took place on a large scale at ca. 2400Ma, leaving metaigneous rocks as restite after extraction of felsic magmas. (3) High-grade metamorphism related to the Pan-African orogeny occurred at 520Ma. (4) Partial melting of crustal material proceeded on a local scale at 490Ma-480Ma, producing slight disturbance to the Rb-Sr whole-rock system.
Willow witches'-broom (WWB) was found in the Edmonton area in 1994 for the first time in Canada. In this study, a simple and sensitive diagnostic method was applied and a comparative molecular genetic analysis was carried out to relate the WWB agent to known phytoplasmas. Upon application of the polymerase chain reaction using a selected pair of primers designed specifically for clover proliferation (CP) phytoplasma, the genomic DNA fragments were amplified from phytoplasma nucleic acids extracted from periwinkle, potato and alfalfa affected by CP, potato witches'-broom (PWB) and alfalfa witches'-broom (AWB), respectively. The results of restricted fragment length polymorphism analysis showed that there are no detectable molecular differences among the amplified phytoplasma DNAs originally extracted from four species of willow (Salix bebbiana Sarg., S. discolorMuhl., S. exigua Nutt, and S. petiolaris Sm.) naturally infected with WWB phytoplasma indicating the presence of only one type of phytoplasma and that WWB phytoplasma belongs to the CP group of phytoplasma organisms.
The obese (ob) gene has recently been isolated by positional genetics, the mutation of which causes marked obesity and diabetes in mice. In the present study, we elucidated the tissue distribution of the ob gene expression in rats and examined the gene expression in genetically obese-hyperglycemic Wistar fatty rats. Northern blot analysis using the rat ob cDNA probe identified a single mRNA species of 4.5 kilobase in size in the adipose tissue, while no significant amount of ob mRNA was detected in other tissues in Sprague-Dawley and Wistar rats. The ob gene expression occurred in the adipose tissue with region-specificities. The rank order of the ob mRNA level in the adipose tissue was epididymal, retroperitoneal, and pericardial white adipose tissue > mesenteric and subcutaneous white adipose tissue ≥ interscapular brown adipose tissue in both rat strains. Furthermore, expression of the ob gene was augmented in all the adipose tissue examined in Wistar fatty rats at the stage of established obesity.
The centromere protein B (CENP-B) recognises DNA of a particular nucleotide sequence. We have identified two repeating units in the DNA-binding domain (DBD) of CENP-B by examining its amino acid sequence closely. The sequences of the two units resemble not only each other but also the sequences of the DBDs of transcription factors, Myb, LexA and DtxR. Since all the above transcription factors have three α-helices in their DNA-binding units, it is likely that each unit of CENP-B is also composed of three α-helices. We discuss possible ways in which the two units of CENP-B are combined along the same DNA.