Nested retrotransposons on the W chromosome of the wild silkworm Bombyx mandarina.

The W chromosome of the silkworms Bombyx mori or B. mandarina is recombinationally isolated from the Z chromosome and the autosomes. We previously characterized a female-specific randomly amplified polymorphic DNA (RAPD), designated W-Yamato, derived from the W chromosome of the wild silkworm Bombyx mandarina. To further analyse the W chromosome of B. mandarina, we obtained a lambda phage clone that contains the W-Yamato RAPD sequence and sequenced the 16.7 kb DNA insert. We found that this DNA comprises a nested structure of at least seven elements: six retrotransposons and one transposable element-like sequence. The transposable element-like sequence is inserted into a micropia-like retrotransposon (Karate). The Karate and the non-long terminal repeat (non-LTR) retrotransposon BMC1 are inserted into a 412-like retrotransposon (Judo). Furthermore, this Judo, and two non-LTR retrotransposons (Kurosawa and Kendo) are inserted into a Pao-like retrotransposon (Yamato). These results indicate that the retrotransposons inserted into the W chromosome are not efficiently removed but accumulate gradually as strata without recombination.

Two novel Pao-like retrotransposons (Kamikaze and Yamato) from the silkworm species Bombyx mori and B. mandarina: common structural features of Pao-like elements.

To characterize the structural features common to Pao-like retrotransposons, we analyzed two lambda phage clones which contain the Pao-like elements from the silkworm species Bombyx mori and B. mandarinia, and copies of Pao itself and ninja of Drosophila simulans, amplified by PCR. We previously identified two randomly amplified polymorphic DNAs (RAPDs), W-Kamikaze and W-Yamato, from B. mori and B. mandarina, which are part of two novel Pao-like retrotransposons, Kamikaze and Yamato, respectively. Complete characterization of these and other elements of this group reported here shows that Pao-like elements have common features that distinguish them from the other groups of LTR-retrotransposons. While the elements of the Ty1-copia group encode only one cysteine and histidine (Cys) motif in their gag-like region, the Pao-like elements specify three Cys motifs. The highly conserved D(35)E motif in the integrase domain of the retrotransposon polyprotein seems to be conserved in Pao-like elements, but the number of amino acid residues between D and E varies and is greater than 35. A comparison of the deduced amino acid sequences of the reverse transcriptase domain revealed the Pao-like elements are members of neither the Ty1-copia nor the gypsy-Ty3 groups. Therefore, we confirmed that the long-terminal-repeat (LTR) retrotransposons should be divided into three major groups (or families), namely the Ty1-copia, gypsy-Ty3, and Pao-like groups.

Identification and genetic mapping of RAPD markers linked to the densonucleosis refractoriness gene, nsd-2, in the silkworm, Bombyx mori.

In the silkworm, Bombyx mori, nonsusceptibility to B. mori densonucleosis virus type-2 (BmDNV-2) is controlled by a recessive gene, nsd-2 (nonsusceptibility to DNV-2). We investigated the genetic linkage between two random-amplified polymorphic DNA (RAPD) markers and the +nsd-2 gene. Initially, we constructed the JSD-2 strain (nsd-2/+), which is congenic to strain J137 (nsd-2/nsd-2) with respect to the chromosome containing the +nsd-2 gene, starting with a female of strain J137 and a male of strain C137 (+nsd-2/+nsd-2). Genomic DNAs were compared between infected individuals of the JSD-2 strain and J137 by a polymerase chain reaction (PCR) with 700 arbitrary 10-mer primers. Two RAPD markers (OPH19R and OPP01R) linked to the +nsd-2 gene were found. For the crossing-over experiment, a female of J137 was crossed with a male (nsd-2/+) of JSD-2. Segregation analysis showed that the most closely linked RAPD marker (OPP01R) was mapped 4.7 cM distant from +nsd-2.

[Inflammatory pseudotumor of the lung with infiltration identified radiographically and hemoptysis].

The patient was a 53-year-old man whose chief complaint was a dry cough and hemoptysis. Chest X-ray films and computed tomographic scans revealed a hazy shadow with unclear margins in the left middle lobe. A diagnosis of inflammatory pseudotumor was made because transbronchial lung biopsy specimens showed proliferation of plasma cells and lymphocytes. Initially, in response to steroid therapy, his clinical condition and pulmonary infiltration improved, but about 30 days after the start of steroid therapy, hemoptysis occurred and the shadow increased, and therefore left segmentectomy was performed. Histology revealed not only proliferation of acute and chronic inflammatory cells but also changes in the vessels. These pathologic findings were considered to be related to the infiltration shadows and the hemoptysis.

[Radiotherapy alone for elderly patients with stage III non-small cell lung cancer].

We undertook a retrospective study of elderly patients with stage III non-small cell lung cancer who had been treated solely with radiotherapy during the period 1986 to 1995. Our study was designed to assess the influence of age on survival and malnutrition in patients aged 75 years or older (elderly group) and patients aged 74 years or younger (younger group). Radiotherapy alone resulted in a median survival period of 11.5 months in the younger group and 6.3 months in the elderly group (p = 0.0043). With the Cox multivariate model, good performance status, age less than 75 years, and good response were significant favorable independent predictors. Furthermore, the elderly group patients more frequently died of respiratory infections and had lower prognostic nutritional indexes than the younger group patients before and after radiotherapy. These findings suggested elderly patients with stage III non-small cell lung cancer who had been treated with radiotherapy alone had a poor prognosis and that malnutrition caused by radiotherapy was a factor contributing to the risk of death from respiratory infection in such patients.

Identification of novel random amplified polymorphic DNAs (RAPDs) on the W chromosome of the domesticated silkworm, Bombyx mori, and the wild silkworm, B. mandarina, and their retrotransposable element-related nucleotide sequences.

Genomic DNAs were compared between males and females of the domesticated silkworm, Bombyx mori, strains C108, C137, J137, p50, and WILD-W (constructed by crossing a wild silkworm, B. mandarina, female with a male of strain C108) by polymerase chain reaction (PCR) with 700 arbitrary 10-mer primers. Four female-specific RAPDs (W-Kabuki, W-Samurai, W-Kamikaze, and W-Yamato) were found. The sex chromosome formulas of B. mori and B. mandarina are ZW (XY) for the female and ZZ (XX) for the male. The four female-specific RAPDs are assumed to be derived from the W chromosome because the other chromosomes are shared by both sexes. A computer search for deduced amino acid sequences of these four RAPDs revealed that all of them showed homology to previously reported amino acid sequences encoded in known retrotransposable elements from various organisms.

Genetic mapping of RAPD markers linked to the densonucleosis refractoriness gene, nsd-1, in the silkworm, Bombyx mori.

In the silkworm, Bombyx mori, nonsusceptibility to B. mori densonucleosis virus type-1 (BmDNV-1) is controlled by a recessive gene, nsd-1 (nonsusceptibility to DNV-1), located on the twenty-first chromosome. We investigated genetic linkage between five random amplified polymorphic DNA (RAPD) markers and the +nsd-1 gene. Initially, we constructed the CSD-1 strain (nsd-1/+) which is congenic to strain C137 (nsd-1/nsd-1) for the twenty-first chromosome, starting with a female of C137 and a male of strain J137 (+nsd-1/+nsd-1). For the crossing over experiment, a female of C137 was crossed with a male (nsd-1/+) of CSD-1. Segregation analysis showed that the most closely linked RAPD marker mapped 3.0 cM distant from +nsd-1. A more specific marker for +nsd-1 was made by converting this RAPD band into a sequence characterized amplified region (SCAR) using a series of newly designed primer pairs based on its DNA sequence.