Replacement of large copepods by small ones with eutrophication of embayments: cause and consequence

Species and size compositions of the planktonic copepod community were compared between two eutrophic embayments, Tokyo Bay and Osaka Bay. Within these bays, the median body weight of the community was lowest at the innermost station and increased gradually offshore. In Tokyo Bay, which is more eutrophic than Osaka Bay, the dominant species was Oithona davisae and the median carbon weight of the community was ca 0.1 µg. In Osaka Bay, Paracalanus sp., Calanus sinicus and Corycaeus spp. were dominant and the median weight was 1–2 order of magnitude higher (2–78 µg) than in Tokyo Bay. Some 40 years ago, when eutrophication was less prominent, Acartia omorii, Paracalanus sp. and Microsetella norvegica comprised a considerable portion of the community in Tokyo Bay. The proliferation of O. davisae might have been caused with the recent change in food particle composition and/or dissociated life cycle of this species from the benthic anoxic layer. Decrease in the size composition of the copepod community may make the embayment ecosystem unfavorable for planktivorous fish, but not for jellyfish, e.g. Aurelia and Bolinopsis. This may also result in an acceleration of the flux of biogenic materials from the embayment to the outer ocean.     

First record of an Early Barremian caprinid rudist from Japan – implications for the palaeobiogeography of the Caprinidae (Bivalvia)

Abstract: Pachytraga Paquier, 1900, the stratigraphically oldest genus of caprinine caprinid rudist, was previously known from only two chronospecies from a single lineage, that is the Hauterivian P. tubiconcha Astre, 1961 and the early Aptian P. paradoxa (Pictet and Campiche, 1869). Here, a new species, Pachytraga? tanakahitoshii, is erected on the basis of isolated left valves recovered from the Osaka and Sanchu areas, south‐west Japan. This species has a moderate shell size (antero‐posterior commissural diameter c. 30 mm), and its left valve is characterized by at least one possibly autapomorphic character (narrow anterior myophore, inclined inwards), as well as a mosaic of primitive (single longitudinal carina developed on the anterior side) and derived (simple marginal canals in the antero‐dorsal valve margin) characters of Mediterranean and Middle East Tethyan Pachytraga. The Japanese Pachytraga? represents the first probable record of this genus outside the Mediterranean/Middle Eastern Tethyan province, and its early Barremian age partly fills the ‘gap’ in its previously known stratigraphical record, although the evolutionary relationship of the Japanese form with Mediterranean and Middle East Tethyan Pachytraga remains unsolved. However, the discovery of early Barremian Pachytraga? in Japan indicates that the evolutionary history of the genus is more complex than previously thought and should thus be discussed in a broader palaeogeographical context that must now include the Pacific.     

Impact of eutrophication on shallow marine benthic foraminifers over the last 150 years in Osaka Bay, Japan

High-resolution foraminiferal analysis was conducted on a short sediment core from the inner part of Osaka Bay, Japan. Changes in foraminiferal assemblages were associated with eutrophication, bottom water hypoxia, and changes in red tide-causing algae. Before the 1920s, the calcareous species Ammonia beccarii, and the agglutinated species Eggerella advena and Trochammina hadai were rare, but calcareous foraminifers in general were abundant. Between the 1920s and 1940s, calcareous foraminifers decreased abruptly in abundance, while A. beccarii, E. advena and T. hadai increased in abundance. This faunal change corresponded in time to an increase in nutrients flowing in through the Yodo River, and bottom water hypoxia related to eutrophication. In the 1960s and 1970s, A. beccarii, E. advena and T. hadai further increased in abundance to become dominant, and many calcareous foraminifers nearly disappeared, corresponding to increasing bottom water hypoxia related to the rapid increase in discharged nutrients during the high economic growth period from 1953 to 1971. After the 1990s, A. beccarii decreased rapidly in abundance and E. advena and Uvigerinella glabra increased in abundance. The main components of red tide-causing algae changed from dinoflagellates to diatoms in the 1980s through 1990s, thus there was a change in the food supply to the benthos, which may have caused the increase in abundance of E. advena and U. glabra.     

Method for enzymatic determination of imidazole acetic acid

A method for enzymatic assay of imidazole acetic acid (ImAA) was developed, based on the strict substrate specificity of imidazole acetate monooxygenase from Pseudomonas sp. [Maki et al. (1969) J. Biol. Chem., 244., 2942–2950], which catalyzes concomitant conversion of NADH to NAD⁺. Thus, ImAA was determined by measuring decrease in absorbancy at 340 nm. Tissue extracts were partially purified and/or concentrated by column chromatography on Bio-Rad AG-1 before enzymatic assay. The lowest measurable level of ImAA by this method was 2 nmol.     

Occurrence and diversity of barnacles on international ships visiting Osaka Bay,Japan, and the risk of their introduction

Abstract

The occurrence and diversity of barnacles attached to the hulls of two intercontinental bulk carriers were studied at the port in Osaka Bay, Japan, to assess the potential risk of introduction of exotic species to the inner part of the bay. Barnacles were sampled from the bulbous bows, near the midship draft marks, and around the propeller posts and rudders. Twenty-two species were found, with 14 of these not previously recorded in Osaka Bay, including four species not previously recorded elsewhere in Japan. From an assessment of environmental similarity between Osaka Bay and native ranges, of the 14 species, Elminius modestus and Amphibalanus variegatus were considered to have the highest risk of introduction to the inner part of the bay.     

A rapid and simple method for the determination of base substitution and frameshift specificity of mutagens

A rapid method for the determination of mutagenic specificity has been developed which makes use of the ochre mutation (TAA) in the his-4 gene of Escherichiacoli. Reversion to His⁺ may occur by suppressor mutation (Type I) or by mutation within the his-4 gene (Type II). The Type I mutations may be further subdivided with respect to the type of suppressor mutation by their ability to suppress nonsense mutants of bacteriophage T4, thus allowing the identification of the responsible base substitution (Kato et al., 1980). The system has the ability to identify mutagens which produce A:T → G:C transitions since only Type II mutants can arise through this base substitution; and in fact, the system confirms the A:T → G:C specificity of the mutagen, N⁴-hydroxycytidine (Janion and Glickman, 1980) since only Type II mutants were induced by treatment with this base analogue.When this system was further tested with several additional mutagens, the results indicate that ethyl methanesulphonate, methyl nitrosourea and ethyl nitrosourea produce primarily Type I revertants which were primarily G:C → A:T transitions. UV-light, γ-rays, 4NQO and methyl methanesulphonate produced all types of base substitutions. The tester strain was further improved by introducing a series of sequenced trp^? frameshift mutations, thus allowing the simultaneous monitoring of frameshift and base-substitution mutations.     

A lycoperdaceous fungus, Arachnion album (Agaricales, Arachniaceae), newly found in Japan

Arachnion album was collected in Osaka and Hyogo Prefectures, western Honshu, Japan. This is a new record of this genus for Japan. Macro- and microscopic features of the species are described and illustrated based on the Japanese specimens, and comparisons with some related taxa of A. album are given.     

Monitoring of the toxic dinoflagellate Alexandrium catenella in Osaka Bay,Japan using a massively parallel sequencing (MPS)-based technique

Since 2002, blooms of Alexandrium catenella sensu Fraga et al. (2015) and paralytic shellfish toxicity events have occurred almost yearly in Osaka Bay, Japan. To better understand the triggers for reoccurring A. catenella blooms in Osaka Bay, phytoplankton community was monitored during the spring seasons of 2012–2015. Monitoring was performed using massively parallel sequencing (MPS)-based technique on amplicon sequences of the 18S rRNA gene. Dense blooms of A. catenella occurred every year except in 2012, however, there was no significant correlation with the environmental parameters investigated. Plankton community diversity decreased before and middle of the A. catenella blooms, suggesting that the decline in diversity could be an indicator for the bloom occurrence. The yearly abundance pattern of A. catenella cells obtained by morphology-based counting coincided with the relative sequence abundances, which supports the effectiveness of MPS-based phytoplankton monitoring.     

Variation in metal concentrations in the brown alga Undaria pinnatifida in Osaka Bay, Japan

In order to evaluate the usefulness of a biomonitoring system using seaweeds for assessing the geographic distribution of metal ions in coastal seawaters, the metal concentrations in the sporophytes of an annual kelp, Undaria pinnatifida (Harvey) Suringar, were collected at 15 localities in Osaka Bay, Japan and compared. About 160 cm² of the blade was cut out from the central part of clean sporophytes, rinsed in filtered seawater using an ultrasonic cleaning bath, and freeze‐dried. After digestion with 12% HNO₃ in a microwave apparatus, metal concentrations in the samples were determined by inductively coupled plasma mass spectrometry. The concentrations (dry weight basis) of most examined elements were in the parts per million range; Cr, 0.48–3.18; Ni, 0.77–5.94; Cu, 3.20–43.8; Zn, 11.3–86.8; Pb, 0.14–3.53. Comparisons of metal compositions of the U. pinnatifida samples from the northeastern area of the bay, which has a large urban population and highly developed industries inland, showed high concentrations of Cd, Pb and Cu compared with the samples from the southwestern area of the bay where the population and industries are much smaller. This suggests that U. pinnatifida metal loads can be used as a marker to track the geographic distributions of the metal concentrations in coastal seawaters, reflecting inland human activities such as shipbuilding and repairing in port areas, and can be used as a useful biomonitoring system of coastal environments for long‐term trend.     

Genome organization and polyploid evolution in the genus Eleusine (Poaceae)

 Eleusine (Poaceae) includes six diploid and three polyploid species and has three basic chromosome numbers, x=8, 9 and 10. The species are annual as well as perennial and all are wild except E. coracana, which is cultivated for grain and fodder in Africa and the Indian subcontinent. Eleusine coracana and E. africana have the same genome and chromosome number (2n=36). Eleusine indica and E. floccifolia are identified as two genome donors to these polyploid species. Eleusine kigeziensis is the third polyploid species of the genus with 2n=38. Its genome may have come from E. jaegeri and from one of the species with x=9, most probably from E. indica. Eleusine indica, E. tristachya, E. floccifolia and E. intermedia with x=9 and two polyploid species, E. coracana and E. africana, are closely related and there is free genetic flow between them. Eleusine multiflora with x=8 is significantly different in morphology and at genomic level from other species. Eleusine jaegeri with x=10 is morphologically similar to E. indica, however, more information is needed to ascertain its position in the genus. Eleusine coracana, which is commonly called finger millet, is a potential and nutritious crop for the increasing population of the world, particularly in arid and semi-arid regions. It can also serve as a gene pool for various important characters and disease resistant genes. Received February 11, 2002; accepted May 27, 2002 Published online: October 14, 2002 Addresses of the authors: Madho Singh Bisht and Yasuhiko Mukai (e-mail: ymukai@cc.osaka-kyoiku.ac.jp), Laboratory of Plant Molecular Genetics, Division of Natural Science, Osaka Kyoiku University, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582, Japan.     

Asymmetric binding of cytochrome b5 to the membrane of human erythrocyte ghosts

The intact, amphipatic form of cytochrome $\text{b}{}_5$ could bind to unsealed ghosts, but not to resealed ghosts, suggesting that the cytochrome could bind only to the inner (cytoplasmic) surface of the ghost membrane. This was further confirmed by the finding that the cytochrome could bind to closed, inside-out vesicles prepared from the ghosts. This asymmetric binding was not due to the exclusive localization of sialic acid and sugar chains on the outer surface of the ghosts membrane, because the cytochrome could not bind to ghosts even after enzymatic removal of these components. Although liposomes consisting of phosphatidylcholine or both phosphatidylcholine and sphingomyelin could effectively bind the cytochrome, this binding capacity was progressively decreased as increasing amount of cholesterol was included in the composition of phosphatidylcholine liposomes. Removal of cholesterol from resealed ghosts by incubation with egg phosphatidylcholine liposomes resulted in the binding of cytochrome $\text{b}{}_5$ to the outer surface of the treated ghosts. The possibility is discussed that the asymmetric binding is due to preferential localization of cholesterol in the outer leaflet of the lipid bilayer that constitutes the ghost membrane.     

Materials for the fungus flora of Japan (53)

Two interesting ascomycetes are described as new to Japan:Ascotricha amesii (Xylariaceae), isolated from garden soil in Osaka; andAuxarthron reticulatum, isolated from forest soil in Tokyo. ADicyma anamorph is associated with the former species. (52): Tubaki, K., Tokumasu, S. and Konno, M., Nippon Kingakukai Kaiho38: 249–250. 1997.     

Induction of the differentiation of memory T killer cells with factors released from macrophage-like cell lines

Macrophage-like cell lines J774.1 and WEHI-3 as well as peritoneal exudate macrophages have been demonstrated to produce factors which induce the differentiation of memory cells into specific T killer cells in the absence of an added antigen. LPS stimulation was required for J774.1 cells and peritoneal macrophages to produce the factors but not for WEHI-3 cells. Interferon seemed to be one of the responsible factors. However, macrophages seem to produce other active factors; one has a molecular weight (MW) of more than 80,000 and lacks thymocyte mitogenic activity; another, with a weak thymocyte mitogenic activity, has a MW of 38,000 to 44,000. The low MW thymocyte mitogenic factor (interleukin-1) showed weak T killer cell differentiating activity.     

Genistein promotes DNA demethylation of the steroidogenic factor 1 (SF-1) promoter in endometrial stromal cells

It has recently been demonstrated that genistein (GEN), a phytoestrogen in soy products, is an epigenetic modulator in various types of cells; but its effect on endometrium has not yet been determined. We investigated the effects of GEN on mouse uterine cells, in vivo and in vitro. Oral administration of GEN for 1 week induced mild proliferation of the endometrium in ovariectomized (OVX) mice, which was accompanied by the induction of steroidogenic factor 1 (SF-1) gene expression. GEN administration induced demethylation of multiple CpG sites in the SF-1 promoter; these sites are extensively methylated and thus silenced in normal endometrium. The GEN-mediated promoter demethylation occurred predominantly on the luminal side, as opposed to myometrium side, indicating that the epigenetic change was mainly shown in regenerated cells. Primary cultures of endometrial stromal cell colonies were screened for GEN-mediated alterations of DNA methylation by a high-resolution melting (HRM) method. One out of 20 colony-forming cell clones showed GEN-induced demethylation of SF-1. This clone exhibited a high proliferation capacity with continuous colony formation activity through multiple serial clonings. We propose that only a portion of endometrial cells are capable of receiving epigenetic modulation by GEN.     

Differences in pupal cold hardiness and larval food consumption between overwintering and non‐overwintering generations of the common yellow swallowtail,Papilio machaon (Lepidoptera: Papilionidae), from the Osaka population

To clarify differences in pupal cold hardiness and larval food consumption between overwintering and non‐overwintering generations of the common yellow swallowtail, Papilio machaon, we reared larvae from the Osaka population under photoperiods of 16 h light : 8 h dark (LD 16:8) (long day) or LD 12:12 (short day) at 20°C. We examined the relationship between food consumption and weight during the final larval stadium and pupae, and measured the pupal supercooling point (SCP). Although the ratio of assimilation to consumption did not differ significantly between photoperiods, the ratio of assimilation to pupal weight differed significantly between individuals reared under long and short days. All diapausing pupae were brown, whereas 56% of non‐diapausing pupae were green with the remainder brown. The mean pupal body length (L), dorsal width (W₁) and lateral width (W₂) were larger in non‐diapausing than in diapausing pupae, and the W₁/L and W₁/W₂ ratios differed significantly between non‐diapausing and diapausing pupae. SCP was approximately –20°C and did not differ among pupae 5, 15 and 30 days after pupation under long‐day conditions. However, under short‐day conditions, mean SCP gradually decreased, stabilizing at approximately –24 to –25°C by 30 days after pupation. After freezing, some diapausing pupae emerged as adults, whereas all non‐diapausing pupae died. Both egestion and assimilation were greater under long‐day conditions. The results revealed that pupae of this papilionid exhibit seasonal polyphenism in physiological and morphological traits. Energy from food appears to be expended on increasing cold hardiness in the overwintering generation and on reproduction in the non‐overwintering generation.     

Expansion of the geographical distribution of an exotic ladybird beetle, Adalia bipunctata (Coleoptera: Coccinellidae), and its interspecific relationships with native ladybird beetles in Japan

The first record of the exotic ladybird beetle, Adalia bipunctata (Coleoptera; Coccinellidae), in Japan was in 1993 at Osaka Nanko Central Park. Since that time, studies on the life history and geographical distribution of A. bipunctata have been ongoing, and its establishment in the Osaka Nanko area has been confirmed. A. bipunctata is a predacious ladybird beetle and a member of a guild that overlaps in habitat and prey with that of native ladybird beetles such as Harmonia axyridis and Menochilas sexmaculatus. We investigated the distribution of A. bipunctata and its interspecific relationships with native predacious ladybird beetles. In some areas, A. bipunctata was dominant in interspecific relationships with native ladybird beetles. For the first 10 years after A. bipunctata was discovered, it occurred only in the Osaka Nanko area, but the present geographical distribution indicates that it has expanded its range. Though the population density of this species was highest at the area recorded first, and tended to decrease in inverse proportion to the distance from Osaka Nanko Central Park, a satellite occurrence was observed in a remote area. The numbers of aphid and tree species (leaf shelter for aestivation and over-wintering) utilized by A. bipunctata have recently increased. Such increases will cause the rate of distribution of A. bipunctata to accelerate. Interspecific competition between H. axyridis and A. bipunctata, which occurs earlier than H. axyridis, may be avoided by desynchronization of the occurrence seasons, and another common predacious ladybird beetle, Coccinella septempunctata, may escape interspecific competition by habitat segregation.     

Isolation of mannan-utilizing bacteria and the culture conditions for mannanase production

A locally isolated strain, Bacillus subtilis NM-39, was selected as an active mannan-utilizing bacterium based on high saccharifying activities on coconut residue and locust bean gum galactomannan. The optimal pH and temperature ranges for activity of the crude enzyme were 5.0 to 6.0 and 50 to 60°C, respectively. The organism gave maximum mannanase activity when grown in liquid mineral salts medium containing 1% (w/v) each of coconut residue and soybean flour, as carbon and nitrogen sources, respectively, at pH 7.0 and in aerobic growth for 28 h at 37°C. High saccharifying activity on coconut mannan was also observed.The authors are with the Industrial Technology Development Institute, Department of Science and Technology, Manila, Philippines. M. Arai and T. Kawaguchi are also currently with the Department of Agricultural Chemistry, College of Agriculture, University of Osaka Prefecture, Sakai, Osaka 593, Japan; T. Yoshida is also with the Faculty of Engineering, Osaka University, Suita, Osaka 565, Japan.     

The Age of Decline? Anxieties about Ageing in Japan

In the context of unprecedented life expectancy, the social position of the Japanese elderly is changing. Anxieties related to ageing are widely experienced by people of all ages and on a number of levels, including nationwide concerns over the ‘ageing population’ and its economic consequences; the ageing of local communities; on an interpersonal level, as older relatives may require care and support; and, finally, in relation to one's own ageing. These anxieties are examined based on ethnographic research in the city of Osaka. The concept of ikigai, often equated with purpose in life but closely associated with the elderly in public discourse, is used to illustrate how ageing implicates a number of apparently unconnected issues. It is argued that anxieties about ageing may ultimately achieve such prominence because they give focus to a range of fundamental human concerns with meaning, death, freedom, and isolation.     

Structural change of myofibrils during mitosis of newt embryonic myocardial cells in culture

Newt embryonic myocardial cells can undergo mitosis in culture. The successive changes in the striation pattern of sarcomeres of myofibrils during mitosis were studied by polarization microscopy without fixing or killing the cells. Birefringence of well-organized striation patterns, i.e., bright A-bands and dark I-bands, was clearly visible in interphase cells and did not show any detectable changes during incubation for 3 h or more. Electron microscopy showed the presence of well-organized myofibrils with Z-bands in these interphase cells. When myocardial cells entered the mitotic stage, the birefringence of striation pattern of their myofibrils gradually changed with the pattern in small parts of the myofibrils gradually becoming indistinct (called 'indistinct striation' in this paper). These indistinct regions increased in size during the mitotic stage. In addition, in some regions of the indistinct striation, the birefringence of sarcomeres gradually decreased and finally disappeared (called 'disappearance of sarcomeres' in this paper). No myocardial cells underwent mitosis without these disruptive changes of the myofibril striation patterns. In the post-mitotic stage, the well-organized striation of the myofibrils reappeared. Electron microscopy showed disorganized sarcomeres without Z-bands in the regions of indistinct striation, and no well-organized myofibrils in the regions where the sarcomeres had disappeared. Thus the well-organized myofibrils with Z-bands became transiently disorganized at least in some parts, during mitosis. They were then reorganized into daughter myocardial cells.