Molecular taxonomy of vestimentiferans of the western Pacific,and their phylogenetic relationship to species of the eastern Pacific III. Alaysia-like vestimentiferans and relationships among families

The phylogenetic status of Alaysia-like vestimentiferans, which were collected at eight sites in the western Pacific, was analyzed on the basis of the nucleotide sequence of part of a mitochondrial gene for cytochrome oxidase I. The 123 individuals analyzed were tentatively classified into four species, which inhabit, respectively, seep areas off the central part of the Japanese mainland, hydrothermal vent fields in the Mid-Okinawa Trough, hydrothermal vent fields in the southern Okinawa Trough, and both seep and vent sites in the Bismarck Sea. From six additional lamellibrachiid specimens from two sites in the Bismarck Sea, two new tentative species were recognized, namely, one from a seep area off Papua New Guinea and another from the hydrothermal vent field at the DESMOS site in the Manus Basin. Phylogenetic analysis using all available sequences of six vestimentiferan families and Alaysia-like vestimentiferans revealed that vestimentiferans could be divided into three groups, namely, lamellibrachiids, escarpiids, and others, even though the monophyly of the third group was supported by only low bootstrap probabilities. Within the first group, the earliest divergence of a tentative lamellibrachiid species from the DESMOS site was apparent. All Alaysia-like vestimentiferans formed a monophyletic group with Arcovestia ivanovi from the Manus Basin, and it is suggested that this group might be derived from vestimentiferans that are endemic to the hydrothermal sites in the Eastern Pacific Rise.     

Reduced hypoosmoregulatory ability and alteration in gill chloride cell distribution in mature chum salmon (Oncorhynchus keta) migrating upstream for spawning

Osmoregulatory ability of mature chum salmon (Oncorhynchus keta) during spawning migration was examined by following the changes in gill Na⁺, K⁺-ATPase activity and in the distribution and morphology of chloride cells. Mature chum salmon caught in Otsuchi Bay, northern Honshu Island, Japan, died within 5 d in seawater (SW) in association with a marked increase in plasma osmolality, whereas the fish transferred to fresh water (FW) maintained plasma osmolality efficiently. Gill Na⁺, K⁺-ATPase activity decreased in both SW-maintained and FW-transferred fish. Well-developed chloride cells, identified by immunocytochemical staining specific for Na⁺, K⁺-ATPase, were present mainly in the filament epithelium of immature fish caught in the ocean. In mature fish caught in the bay, however, additional chloride cells were also found in the lamellar epithelium. The number of filament chloride cells decreased markedly in the mature fish both in SW and in FW, whereas the number of lamellar chloride cells was maintained. These results suggest that the loss of hypoosmoregulatory ability in mature chum salmon may be attributable to the decrease in filament chloride cells and associated decrease in gill Na⁺, K⁺-ATPase activity, and also that appearance of lamellar chloride cells may be preparatory to the forthcoming upstream migration. Received: 14 April 1997 / Accepted: 5 May 1997     

Shell growth and mortality rates in the coral reef gastropod Cerithium nodulosum in Pago Bay,Guam, Mariana Islands

Growth and mortality rates of the gastropod Cerithium nodulosum Bruguière were investigated by repetitive mark-and-recapture censuses for the inner and middle reef flat subpopulations of Pago Bay, Guam, from February to October 1975. Overall population density was about 2 individuals per 100 m² in October. Juveniles (28 to 75 mm shell length) grew at mean rates of from 2.3 to 4.6 mm per month, with great (average coefficient of variation, CV: 32% of the mean) individual variations within the cohorts. The adult stage, which ceases growing in length after forming characteristic shell apertures, was reached within 3 years. Individual adult sizes varied markedly within each subpopulation; the mean shell length was 76.3 mm (standard deviation, SD=6.2, N=129) for the inner and middle reef flat subpopulation and 84.3 mm (SD=6.6; N=127) for the outer reef flat subpopulation. The difference in mean adult shell length between the two subpopulations was highly significant (0.01 level). Mortality rates were estimated from the slopes of regression lines fitted to the catch curves. Assuming tag loss of 10%, crude mortality rates were 15 to 20% per month for the population of C. nodulosum.Contribution No. 103, University of Guam Marine Laboratory.     

Research to develop a predicting system of mammalian subacute toxicity (3) construction of a predictive toxicokinetics model

A new predictive toxicokinetics model was developed to estimate subacute toxicity (target organs, severity, etc.) of non-congeneric industrial chemicals, where the chemical structures and physico-chemical properties are only available. Thus, a physiological pharmacokinetics model, which consists of blood, liver, kidney (these were experimentally found as major toxicological targets), muscle and fat compartments , was established to simulate the chemical concentrations in organs/tissues with pharmacokinetic parameters by means of Runge-Kutta-Gill algorithm. The pliarmacokinetic parameters, i.e. absorption rate, absorption ratio, hepatic extraction ratio of metabolism and renal clearance were calculated by using separately established Quantitative Structure-Pharmacokinetics Relationship equations. The developed predictive model was then applied to simulations of 43 non-congeneric industrial chemicals. The chemical concentrations in organs/tissues after single oral administration were simulated, and their maximum concentrations (Cmax's) and area tinder the concentration-time curves (AUC's) were calculated.Fast Inverse Laplace Transform was newly applied for the purpose of simulation of 28-day repeated dose toxicity.Simulated concentrations of 28 days repeated dose were, however, found to be the same as those of simple repetitions of a single administration per day because of the short half-lives of non-congeneric industrial chemicals.A comparison of subacute toxicity data with Cmax's and AUC's in a single dose scenario suggested that the organs/tissues with relatively high concentrations of tested chemical substances were the most sensitive targets within a chemical.Chemical concentrations in liver, for instance, were correlated with the severity of hepatotoxicity among the chemicals. It was also suggested that to improve and widen the present approach, data of metabolite and reactivity of non-congeneric industrial chemicals to organs/tissues, receptors, etc. should be incorporated into the model.     

Multi-component behavior of fixed-bed adsorption of dioxins by activated carbon fiber

The multi-component behavior of fixed-bed adsorption of dioxins (DXNs) was examined through detailed analyses of the concentration profiles of isomers in fixed-bed activated carbon fiber (ACF). Regularities in both adsorption rates and strengths were clarified. (1) The rate of transfer in the adsorption of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCCDs/DFs) tends to increase with decreasing number of chlorine substituents. Axial dispersion also tends to increase with a decreasing number of chlorine substituents under our experimental conditions. (2) Homologues with the same number of chlorine substituents in PCDDs/DFs have similar adsorption strengths. The adsorption strength of PCDD/DF isomers is probably greater than that of co-planar polychlorinated biphenyls (co-PCB) isomers when the number of chlorine substituents is identical. (3) The adsorption strength of isomers depends on their molecular structure. In PCDDs/DFs the toxic isomers, all of which have vicinal chlorine substituents at the 2, 3, 7 and 8 positions, are relatively strong. It is clear, especially in TeCDDs, that isomers with vicinal chlorine substituents are stronger than isomers without. In co-PCBs, isomers without chlorine substituents at ortho positions are stronger than those with, and (4) A close analogy exists between the adsorption strength order for ACF and the elution order in gas chromatography (GC).     

Effective diffusivity of the uranyl ion in a granite from Inada, Ibaraki, Japan

The effective diffusivity of uranium(VI) in Inada granite has been determined by through-diffusion. Experiments were performed at room temperature (20–25°C) in a 0.1 mol 1⁻¹ KCl solution where uranium is present predominantly as the poorly sorbing UO₂²⁺. An effective diffusivity (D_e) of (3.6 ± 1.6) × 10⁻¹⁴ m² s⁻¹ was obtained, close to that for uranine (nonsorbing organic tracer), but one order of magnitude lower than those obtained for Sr²⁺ and NpO₂⁺, and two orders of magnitude lower than that obtained for I⁻. According to well established theory, a proportional relationship exists between D_e and the diffusivity in the bulk of the solution (D_v). The effective diffusivity obtained in granite was not proportional to D_v. This agrees with results obtained for effective diffusivity in a Swedish granite. The ratio D_e/D_v was found to be not constant but increased with D_e or D_v. This result suggests a limit to the application of the theory.     

Inorganic iodine incorporation into soil organic matter: evidence from iodine K-edge X-ray absorption near-edge structure

The transformation of inorganic iodine (I⁻ and IO₃⁻) incubated in soils with varying amounts of organic matter (Andosols from the surface layer of an upland field and forest, as well as Acrisols from surface and subsurface layers of an upland field) was investigated by using the iodine K-edge X-ray absorption near-edge structure (XANES). After 60 d of reaction, both I⁻ and IO₃⁻ were transformed into organoiodine in surface soils containing sufficient amounts of organic matter, whereas IO₃⁻ remained unchanged in the subsurface soil of Acrisols with low organic matter contents. Transformation of IO₃⁻ into organoiodine was not retarded when the microbial activity in soil was reduced by γ-ray irradiation, suggesting that microbial activity was not essential for the transformation of inorganic iodine into organoiodine. Soil organic matter has the ability to transform inorganic iodine into organoiodine.     

Crystallization Behavior and Dynamic Mechanical Properties of Poly(l-Lactic Acid) with Poly(Ethylene Glycol) Terminated by Benzoate

Effect of the addition of poly(ethylene glycol) terminated by benzoate (PEG-BA) on the crystallization behavior and dynamic mechanical properties of poly(l-lactic acid) PLLA is studied as compared with poly(ethylene glycol) (PEG-OH). It is found that PEG-BA is miscible with PLLA and shows good plasticizing effect. Because PEG-OH having the same degree of polymerization is immiscible with PLLA, the end group in PEG-BA, i.e., benzoate, plays an important role in the miscibility. Furthermore, PEG-BA does not induce the PLLA degradation at melt-processing, whereas PEG-OH leads to the hydrolysis degradation. Finally, the addition of PEG-BA pronounces the crystallization rate of PLLA at low crystallization temperatures and thus enhances the degree of crystallinity at conventional processing. Consequently, the temperature dependence of dynamic mechanical properties are similar to that for isotactic polypropylene.     

DNA synthesis and the cell cycle in the noxious red-tide dinoflagellateGymnodinium nagasakiense

Gymnodinium nagasakiense is a noxious red tide dinoflagellate often associated with damage to fisheries in Japan. DNA synthesis and the cell cycle in this organism were investigated from 1989 to 1990 by determining relative DNA contents of individual cells using an epifluorescence microscopy-based microfluorometry system. The nuclei were stained with the DNA-specific fluorochrome 4-6-diamidino-2-phenylindole (DAPI). Because photosynthetic pigment interferes with the fluorescence from the DAPI-DNA complex, the pigment was eliminated by methanol treatment as a first step in quantitative microfluorometry. Nuclear DNA contents, cell size distribution, cell density, and frequency of paired cells were determined every 2h for 24h using cells grown on a 12h light:dark cycle. DNA synthesis and cell division were tightly phased to a particular period of the light:dark cycle. DNA synthesis (S phase) occurred from 10:00 to 22:00 hrs and was followed by cytokinesis. The presence of such a distinct S phase strongly suggests thatG. nagasakiense has a typical eukaryotic cell cycle. This type of cell cycle makes it possible to estimate speciesspecific in situ growth rate based on the diel pattern of DNA synthesis.     

Vertical distribution,population structure and lifecycle of<Emphasis Type="Italic"> Eucalanus bungii</Emphasis> (Copepoda: Calanoida) in the Oyashio region,with notes on its regional variations

Vertical distribution and population structure of Eucalanus bungii were investigated at site H in the Oyashio region (western subarctic Pacific) from September 1996 through October 1997 to evaluate the species lifecycle pattern and associated ontogenetic vertical migration. Additional temporary samplings were also made at several stations covering the entire subarctic Pacific, Okhotsk Sea and Japan Sea, as a basis for regional comparison of lifecycle features of this species. At site H, a marked phytoplankton bloom occurred from mid-March to June, and E. bungii spawned in April/May in the surface layer. Resulting nauplii and copepodite stage 1 (C1) formed a prominent abundance peak in early June. The C1 developed and reached C5 by August. The development of nauplii through C4 occurred in the surface layer. From August onwards, C5 and a small fraction of C3–C4 sank gradually deeper, and entered diapause to overwinter at >500 m depth. The C5 molted to C6 males and females in February and March, respectively. The C6 males and females mated at 250–500 m depth, and only mated C6 females ascended to the surface layer in April for spawning. Judging from the size of lipid droplets in the body, the C3–C5 specimens deposited lipids in the body through the phytoplankton bloom period, and the lipids were consumed gradually during overwintering. Taking account of sampling season, temporal changes in population structure, and vertical distribution, the data collected from the western subarctic Pacific and Okhotsk Sea are consistent with a 1-year lifecycle for the site H population, while the data from the central and eastern subarctic Pacific were consistent with a 2-year lifecycle. The populations from the southern and southeastern Japan Sea did not fit the features of either lifecycle scenario, and because of their very small population size it is suggested that they originated from the northern Japan Sea. Regional comparison of the prosome length of C6 females, including those in the Bering Sea, indicated significantly larger specimens from the Japan Sea and Okhotsk Sea, and smaller specimens in the eastern subarctic Pacific, as compared with those in the western subarctic Pacific (including site H) and Bering Sea. A possible overwintering mechanism of E. bungii is discussed.Communicated by O. Kinne, Oldendorf/Luhe