JC virus (JCV) together with Simian virus 40 (SV40) and BK virus (BKV), belong to the polyomavirus group and these viruses are neuro-oncogenic to rodents by expression of large T antigen (LT), which binds to cellular p53 and pRB thus reducing the anticancer potential of the cell. The function of LT has not been clarified because small t antigen (st) is transcribed from the same start codon as the overlapping reading frame of LT, and is translated as a different protein with the same N-terminal residues (1-81 amino acids) by a splice-site variant of mRNA. To elucidate the function of LT without st, we constructed plasmids that express LT only by deleting the splicing region including the C-terminus of st, and consequently stable cell lines were established that express only JCLT, SV40LT and BKLT. The growth rates of these cells were examined in colonies on soft agar and it was found that LT alone has a transforming capacity; the order of efficiency being SV40LT, BKLT and JCLT. In addition, to verify the involvement of JCV in human medulloblastoma, eight cases of medulloblastoma, six cases of frozen material and five cases of paraffin-embedded tissues which included three cases of frozen tissues, were examined. PCR assay, genomic Southern blotting, and in situ hybridization were applied to detect the JCV genome, and LT and st were examined by immunohistochemistry; the results were compared with JCV-infected tissues as a positive control. All methods failed to detect not only JCV genome but also LT protein in medulloblastoma and it was concluded that JCV LT has transforming activities in rodent cells, but is not related to human medulloblastoma.

The sunlight that reaches the surface of the earth is composed of polychromatic light with wavelengths ranging from 290 nm to 2500 nm. Ultraviolet (UV) light is a component of sunlight that is harmful to organisms. Although it is known that sunlight induces photoproducts and harmful eŠects such as major DNA damage caused by UV light in the tissues of many species including human skin, it is not clear whether sunlight induces oxidative damage in organisms. In this study, we investigated whether sunlight causes oxidative damage in exposed organisms using Drosophila. Third instar larvae were exposed to sunlight for an evaluation of viability and 8-hydroxydeoxyguanosine (8-OHdG) content. Urate-null Drosophila mutant larvae (ry 506 ), which are sensitive to active oxygen-producing agents, were more sensitive to sunlight lethality than the wild-type strain under limited conditions. This sunlight-induced toxicity in ry 506 larvae was partially prevented by pretreatment of larvae with 400 mM uric acid. The level of 8-OHdG in DNA showed no signiˆcant increase in both strains. In contrast, sunlight was signiˆcantly mutagenic for all seasons as reported previously. These results suggest that sunlight is partly responsible for oxidative damage in Drosophila and that 8-OHdG-formation plays little or no role in sunlight-induced mutation and toxicity.

We identified and analyzed a DNA region that is required for the stable maintenance of plasmids in the genus Sphingomonas. This DNA fragment, a 244 bp, is localized in the upstream region of the repA gene of low-copy-number small plasmid pYAN-1 (4896 bp) of Sphingobium yanoikuyae. It has four inverted repeats and one direct repeat for possible secondary structures. We were able to stabilize not only another unstable plasmid, pYAN-2, in the genus Sphingomonas, but also the unstable plasmid pSC101 without par locus in Escherichia coli. The copy-number levels between the unstable plasmid and the parental plasmid were similar, and these results suggest that the stabilization of unstable plasmids by this DNA region of pYAN-1 was not due to an increase in plasmid copy number. We concluded that the stabilization of the plasmid was due to a plasmid partition mechanism encoded by a DNA fragment of pYAN-1.

Aim To compare the clinical outcomes among women diagnosed with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection during pregnancy, and their neonates, during the period when the Omicron variant predominated in Japan with those of the pre‐Omicron variant period. Methods We conducted a retrospective single‐center cohort study between August 1, 2020, and June 30, 2022. The cohort was divided into pre‐Omicron group (August 1, 2020 to November 30, 2021) and Omicron group (December 1, 2021 to June 30, 2022). The primary outcome was maternal intensive care unit (ICU) admission during the perinatal period. The secondary outcomes were maternal oxygen administration before and after delivery, preterm birth (PTB), and low birth weight (LBW). Results During the study period, 81 pregnant women were admitted to the hospital with SARS‐CoV‐2 infection (pre‐Omicron period, n = 28; Omicron period, n = 53). SARS‐CoV‐2 infection during the Omicron period was associated with lower risk of maternal ICU admission (adjusted‐odds ratio [aOR]: 0.10, 95% confidence interval [CI]: 0.01–1.23, p = 0.072), oxygen administration via a nasal cannula or mask (aOR: 0.18, 95% CI: 0.03–0.96, p = 0.045), PTB (aOR: 0.15, 95% CI: 0.04–0.51, p = 0.002), and LBW (aOR: 0.13, 95% CI: 0.03–0.55, p = 0.005). Conclusion Among pregnant women, SARS‐CoV‐2 infection during the Omicron period was associated with reduced risk of maternal ICU admission, requiring supplemental oxygen, PTB, and LBW. This can be attributable to lower virulence of the Omicron variant and higher vaccination coverage during the Omicron period.