Genetic relationships of char distributed in the watershed border between three river basins in the eastern Chugoku Region, Japan.

Genetic relationships among a subspecies of white-spotted char, Salvelinus leucomaenis pluvius, distributed in the border area of three river basins in the eastern Chugoku region of Japan (the Sendai River, flowing into the Sea of Japan, and the Yoshii and Chigusa rivers, both flowing into the Seto Inland Sea), were investigated based on mitochondrial DNA cytochrome-b gene sequences. A total of 7 haplotypes were recognized and there were 8 polymorphic sites in a 447 bp fragment. Some haplotypes were shared by fish in two adjacent basins across passes, and some were confined to restricted basins. One haplotype estimated to be the oldest could be connected to ‘Gogi’, S. leucomaenis imbrius. Another haplotype, estimated to have derived in the most recent period, was observed in more than half the samples. There was a significant positive correlation between the geographic and genetic distances. These results suggest that genetic distance was more strongly determined by geographic distance than by river-basin location, and may support the possibility of range expansion of char by taking advantage of geologic events

日野川水系に分布するイワナ属魚類の亜種，頭部斑紋型，遺伝子型の組成について

鳥取県日野川水系におけるイワナ属魚類について，ゴギとニッコウイワナ，頭部斑紋型，遺伝子型の組成を調べた。計19の支流から38個体のサンプルが採集され，支流はその発する山塊ごとにグループ化された。ニッコウイワナは水系東部の大山・二子・花見山塊から発する支流に分布したが西部5山塊からの支流には分布せず，対照的にゴギは水系西部の鬼林・道後・三国・船通・鷹入山塊に分布したが東部3山塊には分布しなかった。斑紋型では東部3山塊ではＣ・Ｅ・Ｆ・Ｇ・Ｈは記録されたがＡ・Ｂ・Ｄ型は記録されなかった。一方，西部5山塊ではすべての型が記録された。遺伝子型では6および9つのハプロタイプがそれぞれニッコウイワナおよびゴギ特異的であり，1タイプのみ共通であった。デンドログラムではニッコウイワナおよびゴギそれぞれ5および6つのハプロタイプで構成される亜種特異的なクレードが見られたが，もう一つのクレードは両亜種で形成された。これらの結果は，日野川における両亜種の混棲，ゴギの複数起源性，地形変動等による分布拡大，さらに斑紋の易変異性を示唆する。Composition of 2 subspecies of white-spotted charr, Salvelinus leucomaenis imbrius (“Gogi”) and S. l. pluvius (“Nikko-iwana”), head spot types and genetic types were investigated for the Hino River, Tottori Prefecture, Japan. A total of 38 charr samples was collected from the 19 branches. All the branches were categorized into 8 groups based on the mountain mass from which the branch originates. Nikko-iwana was distributed in the Daisen, Futago and Hanami mountain masses in the eastern part of the basin and was not distributed in the other 5 mountain masses in the western part. In contrast, Gogi was distributed in the western Onibayashi, Dogo, Mikuni, Senzu and Takairi mountain masses and was not distributed in the 3 eastern mountain masses. For head spot types, C, E, F, G and H were distributed in the 3 eastern masses whereas A, B and D were not recorded from these masses. On the other hand, all the types were distributed in the 5 western masses. For genetic types, 6 and 9 haplotypes were Nikko-iwana- and Gogi-specific, respectively. Only a haplotype comprised both subspecies. In the dendrogram, 5 haplotypes constructed an exclusive clade of Nikko-iwana whereas 6 haplotypes constructed an exclusive clade of Gogi. However, the remaining clade was constructed by both subspecies. These results suggest the co-existence of both subspecies in the Hino River, multiple origins of Gogi, movements of charr by topographic events and plasticity of the head spots

西南日本における海産ユスリカの生態に関する研究

西南日本において海産ユスリカの生態に関わる研究を行った。その結果，計20種が採集され，垂直分布では，潮間帯上部あるいは中部域のみに分布する種は少なかったが，下部域のみに分布する種は多かった。基質については岩石面や泥中のみに棲む種は少なかったのに対し，海藻類のみに棲む種は多かった。また，地理的分布では南西諸島や本土外洋沿岸域のみに分布する種は少なかった。一方，数種は，瀬戸内海沿岸と本土外洋沿岸域，本土外洋沿岸域と南西諸島，あるいは全地域に分布することが分かった。また，羽化時期については，Dicrotendipes enteromorphaeは夏季・秋季のみ，S. endocladiaeは周年出現し，他種は秋季・冬季のみあるいは冬季・春季のみに出現した。これらのことから，潮間帯には様々な生活様式を持つ多くの種のユスリカが棲息し，生態系において重要な役割を果たしていることが示唆された。Ecological studies were conducted on marine chironomids in south-western Japan. A total of 20 species was collected. For vertical distribution, only a few species was distributed only at high or middle intertidal zone while many species were distributed only at low zone. For substrate preference, some species were collected only on rocks or in mud while many species were collected only in seaweeds. For geographical distribution, a few species was collected only in the southwestern islands or in the oceanic coast in the Japanese main islands. In contrast, some species were collected in the Seto Inland Sea and the oceanic coast in the main islands, in the oceanic coast in the main islands and the southwestern islands, or in all areas. For seasonal emergence, Dicrotendipes enteromorphae was collected only in summer and autumn, and Semiocladius endocladiae was collected in all seasons. Other species were collected only in autumn and winter, or only in winter and spring. These results suggest that many chironomid species with a variety of lifestyles dwell in intertidal zones and have some important roles in the ecosystems

Field experiments on chironomid phototaxis at the shore of Lake Kojima, Japan

Phototaxis in response to a variety of lamps, including white and colored fluorescent and LED lamps, was compared by species and sex among the chironomids, from Lake Kojima, Okayama Prefecture, Japan. Males were usually much more attracted to lights than were females. Pantanal white attracted the highest number of species among six white lamps. Among five colored lamps, Blue attracted the highest number and Black the lowest number. Among 5 LED lamps, Blue again attracted the highest number and Amber the lowest number. In terms of the number of individuals attracted, Pantanal white was the highest among white lamps for the seven major species. Green and Blue were the highest for the six and seven major species, respectively, and Yellow and Red did not attract the highest number of individuals of any species among colored lamps. Green LED was the highest among LEDs for the seven major species while Amber and Red LEDs were not the highest for any species

Influences of riverside vegetation on the health of ‘Gogi’ char <Article>

Relationships between the riverside vegetation and the health of a subspecies of Japanese common char, Salvelinus leucomaenis imbrius (‘Gogi’) were studied in the Chugoku Mountains. The densities of riverside vegetation comprising deciduous broad-leaf and evergreen coniferous trees, food environments comprising benthic and flowing aquatic animals and falling terrestrial animals, and the relative liver weight of char were examined. It is suggested that a high density of deciduous broad-leaf trees provides a good food environment, resulting in sound health of Gogi char

Genetic relationships in Yamato-iwana, a subspecies of white-spotted char, Salvelinus leucomaenis japonicus

The genetic relationships in a subspecies of white-spotted char, Salvelinus leucomaenis japonicus Oshima, distributed in central Japan, were examined based on the DNA sequences in the mitochondrial cytochrome b region. A total of 12 haplotypes were recognized; haplotypes 2 and 5 were co-dominant. Two large clades were observed in a genetic tree. The Hidaka, Yahagi, and Ibi rivers constructed only the larger clade, whereas the Yogo and Sagami rivers constructed only the smaller clade. A small clade of haplotypes 3, 8, and 10 comprising the samples from the Hidaka and Yahagi rivers and almost all samples from Kiso River was separated deeply. In addition, haplotype 8 from the Nomugi (1446 m) site was estimated to be the newest lineage. However, there were no significant correlations between geographical and genetic distances. These results suggest that this subspecies has multiple origins, its genetic structure is determined by other factors than the river basin, and geological events were scarcely involved in its range expansion

RAPD分析に基くイワナ2亜種，ゴギとニッコウイワナの地理的分布境界の推定

RAPD分析に基づき，日本海流入河川のイワナ2亜種，ゴギとニッコウイワナに特異的な遺伝子型の分布を調べることにより，両者の分布境界を推定した。計16断片が増幅され，1個体から7-14バンドが検出されたが，ゴギあるいはニッコウイワナにのみ特異的なバンドは見られなかった。ゴギ，ニッコウイワナ各々9，15のハプロタイプが見られ，これらのうち，2タイプのみが両亜種共通であった。両者が混棲する可能性がある中間域では24ハプロタイプが見られ，これらのうち，5，9タイプがそれぞれゴギ，ニッコウイワナ特異的であった。ゴギ特異的タイプは鳥取県勝田川が東限，ニッコウイワナ特異的タイプは鳥取県日野川が西限であった。日野川水系では17ハプロタイプが見られ，それらのうち，3，7タイプがそれぞれゴギ，ニッコウイワナ特異的であった。クラドグラムではゴギあるいはニッコウイワナ特異的タイプのみからなる大きなクレードは形成されなかった。これらは，ゴギは東方へ，ニッコウイワナは西方へ分布を広げ，その際に大山山塊が両者にとって分布拡大の障壁となったことを示唆する。We estimated the distribution limits of the 2 subspecies of the white-spotted charr, Salvelinus leucomaenis (‘Iwana’), S. l. pluvius (‘Nikkoiwana’) and S. l. imbrius (‘Gogi’) by examining the distribution of specific genetic types to Nikkoiwana or Gogi in the rivers flowing into the Sea of Japan on the basis of Random Amplified Polymorphic DNA (RAPD). A total of 16 DNA fragments was amplified. Seven to 14 bands were detected from an individual. There were no common bands only to the Nikkoiwana or Gogi. Fifteen and 9 haplotypes were recorded for the Nikkoiwana and Gogi, respectively. Among these, only 2 haplotypes were common to both subspecies. In the intermediate region where both the species were possible to be distributed, 24 haplotypes were detected, among which 9 and 5 types were Nikkoiwana- and Gogi-specific, respectively. Nikkoiwana-specific types were distributed in westernmost to the Hino River, Tottori Prefecture, whereas Gogi-specific types were distributed in easternmost to the Katsuta River, Tottori Prefecture. For the Hino River Basin, 17 haplotypes were detected, among which 7 and 3 types were Nikkoiwana- and Gogi-specific, respectively. In a cladogram, there were no large clades comprising only Nikkoiwana- or Gogi-specific haplotypes. These results suggest westward and eastward range expansions for the Nikkoiwana and Gogi, respectively, and the existence of Mt. Daisen Mountain Mass as a barrier to expansion of both subspecies

Genetic Relationships among Lancelet Populations in Seto Inland Sea Inferred from Mitochondrial DNA Sequences <Article>

Genetic relationships were examined among a total of 74 lancelets, Branchiostoma japonicum (Willey 1897), collected at 16 stations in the Seto Inland Sea on the basis of the sequence of the COI region of mitochondrial DNA. Genetic divergence was usually high at the stations near straits. Besides, there were no significant relationships between geographical and genetic distances of individual lancelets. As many as 62 haplotypes were recognized, among which only three comprised multiple individuals from distant stations, and the remaining ones comprised a single individual. In a dendrogram, some clusters were made up of individuals from nearby stations whereas other ones were made up of those from more or less distant stations. These results suggest that the high genetic heterogeneity of the lancelet population in the Seto Inland Sea is maintained by continuous genetic exchanges via a large-scale dispersion at long planktonic stages driven by tidal and constant currents in this region

Hysteretic Tricolor Electrochromic Systems Based on the Dynamic Redox Properties of Unsymmetrically Substituted Dihydrophenanthrenes and Biphenyl-2,2 '-Diyl Dications: Efficient Precursor Synthesis by a Flow Microreactor Method

A series of biphenyl-2, 2'-diylbis(diarylmethanol)s 3, which have two kinds of aryl groups at the bay region, were efficiently obtained by integrated flow microreactor synthesis. The diols 3NO/NX are the precursors of unsymmetric biphenylic dications 2NO/NX^[2+] which are transformed into the corresponding dihydrophenanthrenes 1NO/NX via 2NO/NX^[+•] upon reduction, when they exhibit two-stage color changes. On the other hand, the steady-state concentration of the intermediate 2NO/NX^[+•] is negligible during the oxidation of 1NO/NX to 2NO/NX^[2+], which reflects unique tricolor electrochromicity with a hysteretic pattern of color change [color 1→color 2→color 3→color 1]