Molecular phylogenetic analyses were conducted to clarify how genetically homogeneous the common Japanese species of Marphysa known as Iwa-mushi is. This is a well-known polychaete used as a fishing bait that was first described as Marphysa iwamushi Izuka, 1907 (type locality: Japan and Taiwan) and later synonymized to Marphysa sanguinea (Montagu, 1813) (type locality: England). The nucleotide sequences of a nuclear gene (18S rRNA) and two mitochondrial genes (16S rRNA and cytochrome c oxidase subunit I (COI)) were compared between specimens newly collected from 14 localities in Japan including commercially sold fishing baits and DDBJ/ENA/GenBank data for congeneric species. Our results show that the Japanese Iwa-mushi is not a single species but a species complex comprising five genetically well-separated clades that were tentatively designated as five undetermined species (Marphysa spp. A, B, C, D, and E). It is unclear whether any of these species corresponds to M. iwamushi. The COI nucleotide sequence of Marphysa sp. A was almost identical to that of M. victori Lavesque, Daffe, Bonifácio & Hutchings, 2017 (type locality: France) and M. bulla Liu, Hutchings & Kupriyanova, 2018 (type locality: China), suggesting that they are conspecific and supporting the hypothesis of Lavesque et al. (2017) that the population in France was introduced from Japan. The COI sequence of Marphysa sp. B corresponds to that of M. maxidenticulata Liu, Hutchings & Kupriyanova, 2018 (type locality: China). Marphysa sp. E was found only in Tokyo Bay and may be an alien species that was introduced by importing live fishing bait. Our results indicate that the European species M. sanguinea is not distributed in Japanese waters.

No abstract

A liquid chromatography-mass spectrometry (LC/MS) method was developed for the separation and determination of linear alkylbenzenesulfonates (C10 -C14 LAS) in environmental water samples using a hydrophilic polymer column . This method involves a solid-phase extraction of the LAS samples with a Sep-Pak PS-2 cartridge. The LAS components were separated on the column with a mobile phase of 29% (w/v) acetonitrile-water containing 0.8 mM di-n-butylammonium acetate and 0.2 M acetic acid, and were detected by mass spectrometry with electrospray ionization. Detection limits of the developed method based on selected ion monitoring (SIM) technique for the C10 -C14 LAS standards were 13 -47 ng L -1 . The concentrations of the C10 -C14 LAS in the environmental water samples ranged between 5 -317 µg L -1 for a river water sample and 0.4 -6.4 µg L -1 for a seawater sample. Linear relationships between the logarithms of retention factors and the alkyl chain lengths for each phenyl positional isomer of LAS could successfully be used for the identification of the isomer peaks.

The photophysical properties of two series of oligosilanes, (1-naphthyl)-(SiMe2) n -(1-naphthyl) (1−5) and (9-anthryl)-(SiMe2) n -(9-anthryl) (6−10) with n = 1−4 and 6, were investigated. In these compounds, two types of interactions, a π−π interaction between two aromatic groups and a σ−π interaction between aromatics and a silicon chain unit, were observed. Intramolecular excimer emission was observed in cyclohexane when n ≥ 2. The strongest excimer emission of 2 and 7 is different from the Hirayama rule (n = 3) proposed for carbon analogues and also shows that intramolecular cycloaddition is minor. The time-resolved fluorescence spectra of an anthryl series revealed that the time constant of excimer formation varied depending on the chain length (82−152 ps). In the cases of 4, 5, and 10, charge-transfer (CT) emission was observed in acetonitrile or THF. The time constant of the CT-state formation for 10 was relatively slow (45 ps), which may indicate a conformational change. Monomer emission from the locally excited state was observed for 1 and 6 in both cyclohexane and acetonitrile.