Molecular evolution in papova viruses and their host species, and in bacteriophages : (evolution, nucleotide substitution, papova viruses)

Comparing homologous genes of three papova viral genomes, we attempt to show the very close relative phylogeny among the viral species and their host species, and therefore the viral species seem to have evolved with their host organisms (SOEDA et al. 1980). Additionally, the DNA-sequence data of bacteriophages [lowercase phi]X174 and G4 and their overlapping genes will be examined for evolutionary patterns. It will then be made evident that overlapping genes have a quite different substitutional pattern with respect to the position of nucleotides in the codons than do non-overlapping sequences. Namely, in overlapping regions the third positions are usually substituted fastest, followed by the first positions, while the second positions are slowest in each gene, though different genes may have different rates of nucleotide substitution. With overlapping genes, this pattern does not apply, but rather is altered because of an interaction between the substitution rates in the two genes involved in an overlap.TAKEO MARUYAMA and EIICHI SOEDA, National Institute of Genetics, Mishima, 411 JAPAN

A 1.5-Mb PAC/BAC Contig Spanning the Prader-Willi Syndrome Critical Region (PWCR)

Prader-Willi syndrome (PWS) is a multiple anomalies/mental retardation syndrome. The putative PWS gene(s) remains unknown, and its occurrence is based on genomic imprinting at chromosome 15q11-q13. We have constructed a 1.5- Mb, fine, physical map of PWS critical region (PWCR) between two markers, D15S9 and D15S174 at 15q11-q13. The map is composed of 32 PAC and 3 BAC clones without any gaps. By the PAC/BAC-end sequencing procedure, a total of 26 sequence tag site (STS) markers were newly generated, and 5 expressed sequence tags (ESTs) were mapped in the region. The contig map was verified by both STS and fluorescence in situ hybridization analyses. Our map has higher resolution, compared with a previous YAC-based map of PWCR. It is useful for further genome analysis, especially on genomic imprinting of this region

Comparison of Interleaved Boost Converter and Two-Phase Boost Converter Characteristics for Three-Level Inverters

A boost converter is used in various applications to obtain a higher voltage than the input voltage. One of the current main circuit systems for hybrid electric vehicles (HEVs) is a combination of a two-phase boost converter (parallel circuit) and a three-phase two-level inverter. In this study, we focus on the boost converter to achieve even higher efficiency and propose an interleaving scheme for a boost converter suitable for a three-level inverter (series circuit). The series circuit has two capacitors connected in series and makes it suitable as a power supply for a three-level inverter. We analyze the input current ripple of the series and parallel circuit in order to show the superiority of the series circuit. Furthermore, we propose a novel output voltage control strategy using an optimal regulator, namely a Linear Quadratic Regulator (LQR), for the series circuit. As a result, we found the input current ripple of the series circuit is smaller than the parallel circuit and demonstrated the superiority of the series circuit. The simulation and experimental results show the effectiveness of the proposed interleaving scheme and optimal regulator

DNA Fragmentation Factor 45 (DFF45) Gene at 1p36.2 Is Homozygously Deleted and Encodes Variant Transcripts in Neuroblastoma Cell Line

Recently, loss of heterozygosity (LOH) studies suggest that more than two tumor suppressor genes lie on the short arm of chromosome 1 (1p) in neuroblastoma (NB). To identify candidate tumor suppressor genes in NB, we searched for homozygous deletions in 20 NB cell lines using a high-density STS map spanning chromosome 1p36, a common LOH region in NB. We found that the 45-kDa subunit of the DNA fragmentation factor (DFF45) gene was homozygously deleted in an NB cell line, NB-1. DFF45 is the chaperon of DFF40, and both molecules are necessary for caspase 3 to induce apoptosis. DFF35, a splicing variant of DFF45, is an inhibitor of DFF40. We examined 20 NB cell lines for expression and mutation of DFF45 gene by reverse transcription (RT)-polymerase chain reaction (PCR) and RT-PCR-single-strand conformation polymorphism. Some novel variant transcripts of the DFF45 gene were found in NB cell lines, but not in normal adrenal gland and peripheral blood. These variants may not serve as chaperons of DFF40, but as inhibitors like DFF35, thus disrupting the balance between DFF45 and DFF40. No mutations of the DFF45 gene were found in any NB cell line, suggesting that the DFF45 is not a tumor suppressor gene for NB. However, homozygous deletion of the DFF45 gene in the NB-1 cell line may imply the presence of unknown tumor suppressor genes in this region