CH/π interactions in the crystal structure of class I MHC antigens and their complexes with peptides

The crystal structure of class I major histocompatibility complex antigens (MHC) bound to their specific ligand peptides were analyzed, in the context of the CH/π interaction, with use of a computer program CHPI. A number of short CH/C_sp² distances have been shown at the boundary of the heavy chain and β2 microglobulin. These interactions are conserved between species, human versus murine. A number of contacts shorter than the conventional van der Waals distance have been disclosed between CH hydrogens and aromatic side-chain groups in the MHC/peptide complexes. The CH/π interaction has been suggested to contribute to the specificity in the complex formation of class I MHC.     

Phylogenetic relationships of the genera Arthroderma and Nannizzia inferred from mitochondrial DNA analysis

The phylogenetic relationship of the genera Arthroderma and Nannizzia, was investigated by mitochondrial DNA analysis based on the restriction-fragment-length polymorphisms. Phylogenetic trees made on ten species. A. benhamiae, A. insingulare, A. quadrifidum, A. simii, A. vanbreuseghemii, N. fulva, N. grubyia, N. gypsea, N. incurvata and N. otae showed no definite distinctions between the genera Arthroderma and Nannizzia. These results support the conclusion of Weitzman et al. that the genera Arthroderma and Nannizzia are congeneric.     

5-(Carboxy-hydroxymethyl)uridine, a new modified nucleoside located in the anticodon of tRNA2Gly from the posterior silk glands of Bombyx mori

A new modified nucleoside located in the anticodon of tRNA2Gly from the posterior silk glands of Bombyx mori has been isolated and its structure determined as 5-(carboxy-hydroxymethyl)uridine mainly by analyses of its UV, 1H NMR, and FD mass spectra.     

Persistence of infectious Friend virus in spleens of mice after spontaneous recovery from virus-induced erythroleukemia.

Persistent infectious virus was detected in the majority of spleens of (C57BL/10 X A.BY)F1 mice after spontaneous recovery from Friend virus-induced erythroleukeima. The Friend murine leukemia helper virus (F-MuLV) was detected in titers up to 3 X 10(5) PFU/g of spleen. The defective spleen focus-forming virus (SFFV) was present in much lower titers and could be detected in cell-free spleen homogenates only after amplification of virus titer by growth of virus in vitro on SC1 cells. The incidence of cells producing F-MuLV alone in spleens after recovery from leukemia was 0.003 to 0.3%, and the incidence of cells producing both F-MuLV and SFFV was less than 0.0001 to 0.01%. In most recovered mouse spleens there appeared to be a selective reduction of SFFV relative to F-MuLV.