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The new recommendation of the International Commission on Radiological Protection for occupational eye dose is an equivalent dose limit to the eye of 20 mSv year-1, averaged over a 5-year period. This recommendation is a drastic reduction from the previous limit of 150 mSv year-1. Hence, it is important to protect physicians' eyes from X-ray radiation. Particularly in interventional radiology (IVR) procedures, many physicians use protective lead (Pb) glasses to reduce their occupational exposure. This study assessed the shielding effects of novel 0.07 mm Pb glasses. The novel glasses (XR-700) have Pb-acrylic lens molded in three dimensions. We studied the novel type of 0.07 mm Pb glasses over a period of seven consecutive months. The eye dose occupational radiation exposure of seven IVR physicians was evaluated during various procedures. All IVR physicians wore eye dosimeters (DOSIRIS™) close to the left side of the left eye. To calculate the shielding effects of the glasses, this same type of eye dosimeter was worn both inside and outside of the Pb lenses. The average shielding effect of the novel glasses across the seven physicians was 61.4%. Our results suggest an improved shielding effect for IVR physicians that use these glasses. No physician complained that the new glasses were uncomfortable; therefore comfort is not a problem. The lightweight glasses were acceptable to IVR physicians, who often must perform long procedures. Thus, the novel glasses are comfortable and reasonably protective. Based on the results of this study, we recommend that IVR physicians use these novel 0.07 mm Pb glasses to reduce their exposure., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Although the clinical value of fluoroscopically guided respiratory endoscopy (bronchoscopy) is clear, there have been very few studies on the radiation dose received by staff during fluoroscopically guided bronchoscopy. The International Commission on Radiological Protection (ICRP) is suggesting reducing the occupational lens dose limit markedly from 150 to 20 mSv/year, averaged over defined periods of five years. The purpose of this study was to clarify the current occupational eye dose of bronchoscopy staff conducting fluoroscopically guided procedures. We measured the occupational eye doses (3-mm-dose equivalent, Hp(3)) of bronchoscopy staff (physicians and nurses) over a 6-month period. The eye doses of eight physicians and three nurses were recorded using a direct eye dosimeter, the DOSIRIS. We also estimated eye doses using personal dosimeters worn at the neck. The mean ± SD radiation eye doses (DOSIRIS) to physicians and nurses were 7.68 ± 5.27 and 2.41 ± 1.94 mSv/6 months, respectively. The new lens dose limit, 20 mSv/year, may be exceeded among bronchoscopy staff, especially physicians. The eye dose of bronchoscopy staff (both physicians and nurses) was underestimated when measured using a neck dosimeter. Hence, the occupational eye dose of bronchoscopy staff should be monitored. To reduce the occupational eye dose, we recommend that staff performing fluoroscopically guided bronchoscopy wear Pb glasses. correct evaluation of the lens dose [Hp(3)] using an eye dosimeter such as the DOSIRIS is necessary for bronchoscopy staff., (© The Author(s) 2020. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

A 6625-base pair transposon, Tn4556, was initially isolated from a Streptomyces strain and a sequence analysis was performed; however, its annotation data remain incomplete. At least three positions were identified as frameshift and base-exchange errors by resequencing. The revised sequence revealed that Tn4556 contains four open reading frames that encode transposase, methyltransferase, isoprenyl diphosphate transferase, and resolvase, respectively. Thirty-eight-base pair inverted repeat (IR) sequences at both ends contained a 1-bp mismatch flanked by a target duplication site, and transposition efficiency was improved by the replacement of imperfectly matched IR-L to perfectly matched IR-L. The detection of Tn4556 transposition was markedly facilitated using a delivery vector carrying a strictly counter-selectable marker for Streptomyces strains.

Ultraviolet-absorbing chemicals are useful in cosmetics and skin care to prevent UV-induced skin damage. We demonstrate here that heterologous production of shinorine, which shows broad absorption maxima in the UV-A and UV-B region. A shinorine producing Corynebacterium glutamicum strain was constructed by expressing four genes from Actinosynnema mirum DSM 43827, which are responsible for the biosynthesis of shinorine from sedoheptulose-7-phosphate in the pentose phosphate pathway. Deletion of transaldolase encoding gene improved shinorine production by 5.2-fold. Among the other genes in pentose phosphate pathway, overexpression of 6-phosphogluconate dehydrogenase encoding gene further increased shinorine production by 60% (19.1 mg/L). The genetic engineering of the pentose phosphate pathway in C. glutamicum improved shinorine production by 8.3-fold in total, and could be applied to produce the other chemicals derived from sedoheptulose-7-phosphate.

The ability of bacterial plasmids to adapt to novel hosts and thereby shift their host range is key to their long-term persistence in bacterial communities. Promiscuous plasmids of the incompatibility group P (IncP)-1 can colonize a wide range of hosts, but it is not known if and how they can contract, shift or further expand their host range. To understand the evolutionary mechanisms of host range shifts of IncP-1 plasmids, an IncP-1β mini-replicon was experimentally evolved in four hosts in which it was initially unstable. After 1000 generations in serial batch cultures under antibiotic selection for plasmid maintenance (kanamycin resistance), the stability of the mini-plasmid dramatically improved in all coevolved hosts. However, only plasmids evolved in Shewanella oneidensis showed improved stability in the ancestor, indicating that adaptive mutations had occurred in the plasmid itself. Complete genome sequence analysis of nine independently evolved plasmids showed seven unique plasmid genotypes that had various kinds of single mutations at one locus, namely, the N-terminal region of the replication initiation protein TrfA. Such parallel evolution indicates that this region was under strong selection. In five of the seven evolved plasmids, these trfA mutations resulted in a significantly higher plasmid copy number. Evolved plasmids were found to be stable in four other naive hosts, but could no longer replicate in Pseudomonas aeruginosa. This study shows that plasmids can specialize to a novel host through trade-offs between improved stability in the new host and the ability to replicate in a previously permissive host.

Several types of environmental bacteria that can aerobically degrade various aromatic compounds have been identified. The catabolic genes in these bacteria have generally been found to form operons, which promote efficient and complete degradation. However, little is known about the degradation pathways in bacteria that are difficult to culture in the laboratory. By functionally screening a metagenomic library created from activated sludge, we had earlier identified 91 fosmid clones carrying genes for extradiol dioxygenase (EDO), a key enzyme in the degradation of aromatic compounds. In this study, we analyzed 38 of these fosmids for the presence and organization of novel genes for aromatics degradation. Only two of the metagenomic clones contained complete degradation pathways similar to those found in known aromatic compound-utilizing bacteria. The rest of the clones contained only subsets of the pathway genes, with novel gene arrangements. A circular 36.7-kb DNA form was assembled from the sequences of clones carrying genes belonging to a novel EDO subfamily. This plasmid-like DNA form, designated pSKYE1, possessed genes for DNA replication and stable maintenance as well as a small set of genes for phenol degradation; the encoded enzymes, phenol hydroxylase and EDO, are capable of the detoxification of aromatic compounds. This gene set was found in 20 of the 38 analyzed clones, suggesting that this 'detoxification apparatus' may be widespread in the environment.

Plasmids are ubiquitous mobile elements that serve as a pool of many host beneficial traits such as antibiotic resistance in bacterial communities. To understand the importance of plasmids in horizontal gene transfer, we need to gain insight into the 'evolutionary history' of these plasmids, i.e. the range of hosts in which they have evolved. Since extensive data support the proposal that foreign DNA acquires the host's nucleotide composition during long-term residence, comparison of nucleotide composition of plasmids and chromosomes could shed light on a plasmid's evolutionary history. The average absolute dinucleotide relative abundance difference, termed delta-distance, has been commonly used to measure differences in dinucleotide composition, or 'genomic signature', between bacterial chromosomes and plasmids. Here, we introduce the Mahalanobis distance, which takes into account the variance-covariance structure of the chromosome signatures. We demonstrate that the Mahalanobis distance is better than the delta-distance at measuring genomic signature differences between plasmids and chromosomes of potential hosts. We illustrate the usefulness of this metric for proposing candidate long-term hosts for plasmids, focusing on the virulence plasmids pXO1 from Bacillus anthracis, and pO157 from Escherichia coli O157:H7, as well as the broad host range multi-drug resistance plasmid pB10 from an unknown host.

Little is known about the range of hosts in which broad-host-range (BHR) plasmids can persist in the absence of selection for plasmid-encoded traits, and whether this "long-term host range" can evolve over time. Previously, the BHR multidrug resistance plasmid pB10 was shown to be highly unstable in Stenotrophomonas maltophilia P21 and Pseudomonas putida H2. To investigate whether this plasmid can adapt to such unfavorable hosts, we performed evolution experiments wherein pB10 was maintained in strain P21, strain H2, and alternatingly in P21 and H2. Plasmids that evolved in P21 and in both hosts showed increased stability and decreased cost in ancestral host P21. However, the latter group showed higher variability in stability patterns, suggesting that regular switching between distinct hosts hampered adaptive plasmid evolution. The plasmids evolved in P21 were also equally or more stable in other hosts compared to pB10, which suggested true host-range expansion. The complete genome sequences of four evolved plasmids with improved stability showed only one or two genetic changes. The stability of plasmids evolved in H2 improved only in their coevolved hosts, not in the ancestral host. Thus a BHR plasmid can adapt to an unfavorable host and thereby expand its long-term host range.