Masatoshi Morita

Effects of triphenyltin chloride and five other organotin compounds on the development of imposex in the rock shell, Thais clavigera

The imposex promotion activities of six organotin compounds--tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPT), diphenyltin (DPT) and monophenyltin (MPT)--were examined by injection experiments with the rock shell, Thais clavigera (Prosobranchia; Muricidae). TPT and TBT had strong effects on the development of imposex in the rock shell (p<0.001). The other organotin compounds (DBT, MBT, DPT and MPT) had no or less effects on the development of imposex in T. clavigera. The difference between the effects of TPT and TBT was statistically insignificant (p>0.01). The effects of these compounds are estimated, from the relationships between TBT or TPT concentration in tissue and mean penis length of females after injections, to be approximately the same.

Imposex and organotin compounds in Thais clavigera and T. bronni in Japan

Rates of occurrence and degrees of imposex, and tissue concentrations of organotin compounds (tributyltin, TBT; dibutyltin, DBT; butyltin, MBT; triphenyltin, TPT; diphenyltin, DPT; and phenyltin, MPT) in the rock shell, Thais clavigera and T. bronni (Mollusca: Gastropoda) were investigated at 32 sites in Japan from May 1990 to October 1992. The rate of occurrence of imposex was 100% in both species, at almost all sites surveyed. Degrees of imposex indicated by relative penis length (RPL) index reflected the pollution levels not only of TBT, but also TPT. In heavily polluted areas, many individuals were found with oviducts which were blocked by vas deferens development, and capsule glands which were filled with aborted egg masses. These organisms were thought to be sterile.

Determination of estrogens and their conjugates in water using solid-phase extraction followed by liquid chromatography–tandem mass spectrometry

An analytical procedure for the determination of steroid estrogens and their conjugates was developed and applied to aqueous environmental samples. The analytes of 15 compounds were solid-phase extracted and fractionated into two fractions: one containing unconjugated (free) steroids and the other containing conjugates (sulfates and glucuronides). Identification and quantification were carried out using liquid chromatography coupled with tandem mass spectrometry. The recoveries for each compound ranged from 57 to 116% and reproducibilities represented as RSD ranged from 2.9 to 17%. Some of the sulfates and free compounds were detected in environmental samples, whereas most of the conjugates were below the detection limits.

Fish otolith reference material for quality assurance of chemical analyses

Abstract A certified reference material (CRM) for major, minor and trace element analysis was prepared from sagittal otolith of red emperor ( Lutjanus sebae ) at National Institute for Environmental Studies (NIES), Japan in collaboration with Western Australian Marine Research Laboratories (WAMRL), Australia. Otoliths (1.4 kg) were cleaned, pulverized, sieved to pass a 105-μm screen and homogenized, and 375 vials, each containing 3 g, were prepared. Certified value was determined for Na, Mg, K, Ca, Sr and Ba through a collaboration involving NIES and five other laboratories. The certified value (mean of the means reported from the collaborating laboratories plus or minus the 95% confidence interval) were 97.0±4.2 μmol/g (0.223±0.010%) for Na, 0.88±0.06 μmol/g (21±1 μg/g) for Mg, 7.21±0.20 μmol/g (282±8 μg/g) for K, 9.69±0.11 mmol/g (38.8±0.5%) for Ca, 26.9±0.5 μmol/g (0.236±0.005%) for Sr and 21.1±0.6 nmol/g (2.89±0.09 μg/g) for Ba. Reference values were given for Cu [12 nmol/g (0.74 μg/g)], Zn [7.2 nmol/g (0.47 μg/g)], Cd [0.025 nmol/g (0.0028 μg/g)] and Pb [0.11 nmol/g (0.023 μg/g)] based on definitive analyses at NIES. This CRM will be of practical value for the quality assurance of solution-based elemental analysis of fish otoliths and other marine aragonites.

Juvenile hormone agonists affect the occurrence of male Daphnia

The water flea Daphnia magna reproduces primarily by cyclic parthenogenesis. Environmental stimuli that signal a change to adverse conditions induce the organisms to switch from parthenogenesis to gamogenetic reproduction. During the gamogenetic period, they produce male daphnids and dormant resting eggs, which can survive prolonged periods of environmental adversity. However, little is known about the mechanisms associated with the switch from parthenogenesis to gamogenetic reproduction. We investigated the effects of several juvenoids on sex determination in Daphnia. Females less than 24 h old were exposed to various concentrations of the test substance and were observed for 21 days. It was found that they can trigger the appearance of male daphnids: the percentage of males in the population increases to a level greater than what occurs under ordinary environmental conditions. We found that methylfarnesoate, juvenile hormone III, methoprene, and the phenoxyphenoxy derivatives pyriproxyfen and fenoxycarb (both insecticides) reduced the production of offspring and produced sex ratios dominated by male daphnids. Pyriproxyfen and fenoxycarb showed striking effects at low concentrations. Exposure to either of these chemicals at a concentration of 330 ngl(-1) caused adult females to produce almost all male neonates. Methylfarnesoate, juvenile hormone III, and methoprene showed an effect in inducing male production at higher concentrations (3.7 x 10(3), 3.3 x 10(5), and 1.3 x 10(5) ngl(-1), respectively). Our findings suggest that juvenile hormone agonists, including some insecticides, affect the chemical signaling responsible for inducing the production of male offspring.

Imposex in Japanese gastropods (neogastropoda and mesogastropoda) : effects of tributyltin and triphenyltin from antifouling paints

In Japan, marine pollution by organotin compounds is serious and imposex is known to occur in marine gastropods. However, a detailed survey on imposex had not previously been conducted. The first country-wide survey and laboratory experiments on imposex in Japanese gastropods has now been carried out, and the results are reported herein.

Bisphenol A causes hyperactivity in the rat concomitantly with impairment of tyrosine hydroxylase immunoreactivity

We examined the effects of bisphenol A, an endocrine disruptor, on rat behavioral and cellular responses. Single intracisternal administration of bisphenol A (0.2‐20 μg) into 5‐day‐old male Wistar rats caused significant hyperactivity at 4–5 weeks of age. Rats were about 1.6‐fold more active in the nocturnal phase after administration of both 2 and 20 μg of bisphenol A than were control rats. The response was dose‐dependent. Based on DNA macroarray analyses of the midbrain, bisphenol A decreased by more than twofold gene expression levels of the dopamine D4 receptor at 4 weeks of age and the dopamine transporter at 8 weeks of age. Furthermore, bisphenol A decreased by more than twofold gene expression levels of the dopamine D4 receptor at 4 weeks of age and the dopamine transporter at 8 weeks of age. We conclude that bisphenol A affected central dopaminergic system activity, resulting in hyperactivity due most likely to a large reduction of tyrosine hydroxylase activity in the midbrain.

Motor hyperactivity caused by a deficit in dopaminergic neurons and the effects of endocrine disruptors: a study inspired by the physiological roles of PACAP in the brain

Recent studies have revealed that the pituitary adenylate cyclase-activating polypeptide (PACAP) might act as a psychostimulant. Here we investigated the mechanisms underlying motor hyperactivity in patients with pervasive developmental disorders, such as autism, and attention-deficit hyperactivity disorder (ADHD). We studied the effects of intracisternal administration of 6-hydroxydopamine (6-OHDA) or endocrine disruptors (EDs) on spontaneous motor activity (SMA) and multiple gene expression in neonatal rats. Treatment with 6-OHDA caused significant hyperactivity during the dark phase in rats aged 4-5 weeks. Motor hyperactivities also were observed after treatment with endocrine disruptors, such as bisphenol A, nonylphenol, diethylhexyl phthalate and dibutyl phthalate, during both dark and light phases. Gene-expression profiles produced using cDNA macroarrays of 8-week-old rats with 6-OHDA lesions revealed the altered expression of several classes of gene, including the N-methyl-D-aspartate (NMDA) receptor 1, glutamate/aspartate transporter, gamma-aminobutyric-acid transporter, dopamine transporter 1, D4 receptor, and peptidergic elements such as the galanin receptor, arginine vasopressin receptor, neuropeptide Y and tachykinin 2. The changes in gene expression caused by treatment with endocrine disruptors differed from those induced by 6-OHDA. These results suggest that the mechanisms underlying the induction of motor hyperactivity and/or compensatory changes in young adult rats might differ between 6-OHDA and endocrine disruptors.

Arsenic Transformations in Short Marine Food Chains studied by HPLC-ICP MS

The chemical forms of arsenic in some herbivorous or mainly herbivorous marine animals and, in some cases, the algae on which they feed were determined by HPLC-ICP MS. In most cases arsenobetaine was present in the animals as well as arsenosugars consumed directly from the algae. However in the case of copepods Gladioferens imparipes fed only on the diatom Chaetoceros concavicornis which had been grown in axenic culture, arseno-betaine was absent. Arsenobetaine was also absent from the muscle of the silver drummer Kyphosus sydneyanus, although trimethyl-arsine oxide was present. This is the first reported case of the absence of arsenobetaine in a marine teleost fish and may be related to its fermentative faculty for digesting the macroalgae that it consumes.

Isolation and identification of arseno-lipid from a brown alga, Undariapinnatifida (Wakame)

A brown alga, U.pinnatifida, was extracted with chloroform-methanol, and the arsenic compound in chloroform fraction was purified further by hexane/acetonitrile partition, chromatography on Sephadex LH-20, and on silicagel HPLC. Alkaline digestion of the purified compound gave the water-soluble arsenic compound, compound 2, and palmitic acid methyl ester, indicating that the lipid-soluble compound is dipalmitoylglycerophospho-2-hydroxypropyl-5-deoxy-5-(dimethylarsinoyl)-β-ribofuranoside (compound 1).