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Fishes expressing a fluorescent protein in germ cells are useful to perform germ cell transfer experiments for conservation study. Nonetheless, no such fish has been generated in endangered endemic fishes. In this study, we tried to produce a fish expressing Venus fluorescent protein in germ cells using Honmoroko (Gnathopogon caerulescens), which is one of the threatened small cyprinid endemic to the ancient Lake Biwa in Japan. To achieve germ cell-specific expression of Venus, we used piwil1 (formally known as ziwi) promoter and Tol2 transposon system. Following the co-injection of the piwil1-Venus expression vector and the Tol2 transposase mRNA into fertilized eggs, presumptive transgenic fish were reared. At 7 months of post-fertilization, about 19% (10/52) of the examined larvae showed Venus fluorescence in their gonad specifically. Immunohistological staining and in vitro spermatogenesis using gonads of the juvenile founder fish revealed that Venus expression was detected in spermatogonia and spermatocyte in male, and oogonia and stage I and II oocytes in female. These results indicate that the Tol2 transposon and zebrafish piwil1 promoter enabled gene transfer and germ cell-specific expression of Venus in G. caerulescens. In addition, in vitro culture of juvenile spermatogonia enables the rapid validation of temporal expression of transgene during spermatogenesis.

Despite a recent study of Honmoroko, Gnathopogon caerulescens, reproduction in lagoons around Lake Biwa having demonstrated the importance of lagoon inlets as spawning habitats for the species, no quantitative studies have examined the conditions determining the environmental suitability of spawning habitats. A survey of Honmoroko egg distribution in the inlets indicated that mature Honmoroko selectively spawn in regions of greater current velocity, utilizing a greater abundance of submerged plants and larger substrate (gravel and pebble) size, not utilizing the emergent plants, habitat characteristics supported by a generalized linear mixed model. The biological information gained is essential for future conservation of Honmoroko spawning habitats.

Fishes expressing a fluorescent protein in germ cells are useful to perform germ cell transfer experiments for conservation study. Nonetheless, no such fish has been generated in endangered endemic fishes. In this study, we tried to produce a fish expressing Venus fluorescent protein in germ cells using Honmoroko (Gnathopogon caerulescens), which is one of the threatened small cyprinid endemic to the ancient Lake Biwa in Japan. To achieve germ cell-specific expression of Venus, we used piwil1 (formally known as ziwi) promoter and Tol2 transposon system. Following the co-injection of the piwil1-Venus expression vector and the Tol2 transposase mRNA into fertilized eggs, presumptive transgenic fish were reared. At 7 months of post-fertilization, about 19% (10/52) of the examined larvae showed Venus fluorescence in their gonad specifically. Immunohistological staining and in vitro spermatogenesis using gonads of the juvenile founder fish revealed that Venus expression was detected in spermatogonia and spermatocyte in male, and oogonia and stage I and II oocytes in female. These results indicate that the Tol2 transposon and zebrafish piwil1 promoter enabled gene transfer and germ cell-specific expression of Venus in G. caerulescens. In addition, in vitro culture of juvenile spermatogonia enables the rapid validation of temporal expression of transgene during spermatogenesis.

Migration of wild and cultivated juvenile honmoroko Gnathopogon caerulescens of from the spawning and nursery areas in Lake Biwa were investigated, both in the Ibanaiko Lagoon and its outlet to Daido River, using beam-trawl surveys in 2013 and 2014. The study demonstrated migration of G. caerulescens from a nursery lagoon toward Lake Biwa after the juvenile stage. These findings appear to be the first direct evidence for migration of an exclusively pelagic cyprinid species from a littoral nursery to a pelagic adult habitat in a large deep lake.

Otolith growth increments in wild-caught alizarin complex one (ALC)-marked honmoroko Gnathopogon caerulescens were examined to verify the veracity of the age determination method in cyprinids. ALC-marked G. caerulescens recaptured from their natural environment had lapilli increment counts outside the ALC ring mark that had formed on a daily basis during the juvenile stage. This apparently being the first direct evidence of daily periodicity of otolith increment formation in wild-caught cyprinids.

Honmoroko Gnathopogon caerulescens is a critically endangered species and important for commercial fisheries; thus stock enhancement programs are being conducted to restore resources. We evaluated the genetic population structure of field collected samples including spawned eggs around spawning areas in Lake Biwa and the extent of genetic diversity in wild samples and hatchery stocks using sequences of mitochondrial cytochrome b gene. Pairwise Φst analysis and AMOVA clearly showed minimal population structure and haplotype network did not reveal any clear geographic pattern in Lake Biwa. It is probable that strays spawn in non-natal spawning areas, resulting in significant levels of gene flow among spawning areas. Genetic characteristics of hatchery stock F1, F2, and F3 were similar to those of wild samples in terms of haplotype diversity, nucleotide diversity and pairwise Φst values. These results indicate that the relatively high genetic diversity at its initiation was retained due to a lot of broodstock over two successive generations. Accordingly we propose that the current Honmoroko breeding method is appropriate for conserving the genetic diversity of Honmoroko and that the hatchery stock are genetically compatable for release and stock enhancement.

The influence of hatching date on the sex ratio of wild Gnathopogon caerulescens was examined. Cohorts reared from eggs collected in the early and middle parts of the spawning season showed almost balanced sex ratios, with female bias in some cohorts. Cohorts born later in the season mostly displayed male bias, and the mean proportion of males later in the season was significantly higher than in early- and mid-season cohorts. These results indicate that the sex ratio of G. caerulescens changes with the time of breeding, increasing along with the ambient water temperature of the lake.

Establishing a cell line from endemic species facilitates the cell biological research of these species in the laboratory. In this study, an epithelium-like cell line RME1 was established from the blastula-stage embryos of the critically endangered cyprinid Honmoroko Gnathopogon caerulescens, which is endemic to ancient Lake Biwa in Japan. To the best of our knowledge, this is the first embryonic cell line from an endangered fish species. This cell line is well adapted to grow at 28°C in the culture medium, which was successfully used for establishing testicular and ovarian cell lines of G. caerulescens, and has displayed stable growth over 60 passages since its initiation in June 2011. Although RME1 did not express the genes detected in blastula-stage embryos, such as oct4, sox2, nanog, and klf4, it showed a high euploidy rate (2n = 50; 67.2%) with normal diploid karyotype morphology, suggesting that RME1 retains the genomic organization of G. caerulescens and can prove to be a useful tool to investigate the unique properties of endangered endemic fishes at cellular level.

SummarySperm cryopreservation is a valuable conservation method for endangered fish species. Here we report an easy and efficient cryopreservation method for juvenile whole testis by vitrification and successful sperm production from the vitrified whole testis viain vitrospermatogenesis in the critically endangered cyprinid honmoroko (Gnathopogon caerulescens). Juvenile testis (approximately 10 mm in length and 1 mm in width), consisting predominantly of spermatogonia, were aseptically dissected out and adherent fatty and non-testicular tissues were subsequently removed. Then, the testes were rapidly cooled on a nylon mesh by direct immersion in liquid nitrogen after serial exposures to pretreatment solution (PS), containing 2 M ethylene glycol (EG) and 1 M dimethyl sulfoxide (DMSO), for 20 or 30 min and vitrification solution (VS), containing 3 M EG, 2 M DMSO, and 0.5 M sucrose, for 5, 10, or 20 min. The highest survival rate of testicular cells (84.0%) was obtained from testes vitrified by immersion in PS for 20 min and in VS for 10 min. Spermatogonia were recovered from the vitrified testis by dissociation and cell culture produced many haploid sperm. Fertility and developmental competence were confirmed byin vitrofertilization assays. These results indicate that the vitrification of juvenile whole testis provides a new strategy to preserve the genetic resources of endangered fishes without affecting their reproductive population.

The age composition, and age- and size-dependent sex ratios of mass samples of “Honmoroko”, Gnathopogon caerulescens, were examined in Lake Biwa. The fish ranged from 0 to 2 years in age, but were mostly age 0 (97.9 %). The proportion of females was 48.6 % for age 0, 73.2 % for age 1, and 90.0 % for age 2 fish. Age 0 fish were significantly male biased, while ages 1 and 2 were significantly female biased, though the grand total showed a balanced sex ratio. The proportion of females was 48.0 % or less among age 0 fish in size classes of less than 9 cm in standard length (SL) and significantly different from a female:male ratio of 1:1 in such size classes, except for the 4–5.99 class. In size classes of 9 cm SL or greater, the proportion of females among age 0 fish was greater, more than 71.3 %, with significant differences from a balanced sex ratio for all such classes. These results suggest that G. caerulescens can be regarded as essentially an annual fish and that its spawning habits ought to result in a higher mortality for males than females, thus leading to female-biased sex ratios at ages 1 and 2.

Diel drift patterns of larvae of the endangered cyprinid Gnathopogon caerelescens in an inlet of the Ibanaiko Lagoon, connected to Lake Biwa in Japan, were assessed in April 2012. Peak occurrence of yolk-sac larvae was within a few hours after dark. Drift of newly hatched larvae is considered to be an important biological mechanism that ensures larval dispersal and recruitment from the inlets (spawning grounds) to the lagoon which functions as a nursery ground.

Egg size affects larval size, growth rate, survival and fecundity with maternal fitness being maximized by a trade-off between egg size and fecundity. Production of a small number of large eggs maximizes female fitness under poor food conditions, as does a large number of small eggs under rich food conditions. Gnathopogon caerulescens (Honmoroko) spawns over a wide range of water temperature from spring to summer. Thus, we determined whether or not egg size varied with water temperature and how egg size influenced hatchling size at different water temperature. Changes in egg size strongly correlated with seasonal changes in water temperature around the lake, regardless of time and area. An experiment using eggs from the lake indicated that hatchling size has a significant positive relationship with egg size in water temperatures of 24 °C. On the other hand, a lower incubation temperature, similar to that likely to be encountered at the beginning of the spawning season, resulted in a smaller hatchling size, eggs requiring a longer time to hatch. At the beginning of the spawning season, therefore, egg size may have a lesser impact on hatching size in the natural environment of Honmoroko because of the relatively lower temperatures. Although fish larvae below a certain threshold of effective body size are generally not expected to have a high early survival rate due to, for example, a lower competitive ability or a high susceptibility to predation, seasonal egg size variation in Honmoroko may be adaptive so as to enhance the likehood of early survival by establishing an effective body size under changing water temperature conditions.

Landlocking of salmon relaxes selective pressures on hypoosmoregulatory ability (seawater adaptability) and may lead to the abandonment of its physiological system. However, little is known about the mechanism and consequence of the process. Biwa salmon is a strain/subspecies of Oncorhynchus masou that has been landlocked in Lake Biwa for an exceptionally long period (about 500,000 years) and has low ability to adapt to seawater. We compared activity of gill Na+,K+-ATPase (NKA) of Biwa salmon with those of anadromous strains of the same species (masu and amago salmon) during downstream migration periods and after exogenous hormone treatment. Gill NKA activity in anadromous strains increased during their migration periods, while that in Biwa salmon remained low. However, treatments of Biwa salmon with growth hormone (GH) and cortisol increased gill NKA activity. Cortisol treatment also improved the whole body seawater adaptability of Biwa salmon. Receptors for GH and cortisol responded to hormonal treatments, whereas their mRNA levels during downstream migration period were essentially unchanged in Biwa salmon. Circulating levels of cortisol in masu salmon showed a peak during downstream migration period, while no such increase was seen in Biwa salmon. The present results indicate that Biwa salmon can improve its seawater adaptability by exogenous hormonal treatment, and hormone receptors are capable of responding to the signals. However, secretion of the endogenous hormone (cortisol) was not activated during the downstream migration period, which explains, at least in part, their low ability to adapt to seawater.

The sex ratios of the nigorobuna Carassius auratus grandoculis reared in paddy fields during the sex differentiation periods of larval and juvenile stages were examined, since the phenotypic expression of sex in the fish is thermolabile, so that sex determination is under the control of genetic factors and temperature. After 2 days from hatching, the larvae were introduced into five paddy fields at five different densities in late May. After 37 or 41 days from hatching the juveniles were collected when the water was drained from the paddy fields, and reared in laboratory tanks supplied with running freshwater pumped from the lake shore until the age of 144–164 days. The mean water temperatures in the paddy fields were 22.4–24.1 oC, and the maximum water temperature during the day frequently exceeded 30 oC during the supposed critical period of sex determination of the fish. The sex ratios in the five paddy fields did not show a male-bias. Instead, all fields produced either balanced or slightly female-bias sex ratios. These results suggest that temporary high and fluctuating temperatures in paddy fields with low mean temperatures have hardly any masculinization effects on genotypic females of C. auratus grandoculis during sex differentiation stages.

The honmoroko has been inferred to have an XX/XY sex determination system, but the parental genome can also affect the sex ratio of the offspring. The extent of parental effects on sex determination was examined by checking the sex ratios of F1 and F2 gynogenetic diploids and control diploids. Eleven gynogenetic broods from different females consisted of all or nearly all females, but eight broods showed a variable proportion of males (

Fish Sertoli cells play a critical role in spermatogenesis by mediating androgen and progestogen signaling. Their hormonal response, however, considerably differ among species. Therefore it would be ideal to use Sertoli cells originated from the fish of interest to investigate the effects of hormones as well as endocrine disrupting chemicals (EDCs). The aim of this study was to investigate the responses to reproductive hormones and EDCs of a Sertoli cell line that we established from an endemic cyprinid Gnathopogon caerulescens. As the Sertoli cell line expressed endogenous androgen and progestogen receptors, we were able to detect hormone responses by transfecting only a reporter vector (pGL4.36) expressing luciferase under the control of the mouse mammary tumor virus-long terminal repeat (MMTV-LTR) promoter into the cell line. Unlike previous reporter gene assays using fish steroid hormone receptors expressed in mammalian cell lines, luciferase activities were induced by the fish specific androgen (11-ketotestosterone) and progestogen (17α,20β-dihydroxy-4-pregnen-3-one), but not by testosterone and progesterone, at physiologically relevant concentrations. Furthermore, we found 4-nonylphenol (NP) but not bisphenol A showed strong anti-androgenic effects, implying that NP may have direct anti-androgenic effects on fish Sertoli cells in vivo. This is the first evidence, to the best of our knowledge, of anti-androgenic effects of NP in a fish Sertoli cell line. In addition, neither NP nor BPA showed anti-progestogenic effects. These results suggest that the Sertoli cell line established from the fish of interest can be a useful in vitro tool for investigating the mechanisms of reproductive hormones and EDCs in the specific fish.

Many endemic fish species are threatened with extinction. Conservation strategies and the restoration of endemic fish after extinction must therefore be investigated. Although sperm cryopreservation is indispensable for the conservation of endangered fishes, the limited number of mature fish and limited availability (volume and period) of sperm from small endemic fish hinders the optimization and practical use of this material. In this report, we demonstrate the in vitro differentiation of fertile sperm from cryopreserved spermatogonia of juveniles of the endangered small cyprinid honmoroko (Gnathopogon caerulescens), which is endemic to Lake Biwa in Japan. The entire process of spermatogenesis was recapitulated in vitro using cryopreserved spermatogonia of non-spawning adult and juvenile fish. The differentiation of sperm from spermatogonia was captured as a time-lapse video and confirmed by 5-ethynyl-2′-deoxyuridine (EdU) incorporation into sperm. Fertility was demonstrated by artificial insemination. These results suggest that the combination of cryopreservation of spermatogonia and in vitro sperm differentiation will provide a new and promising strategy for the preservation of paternal genetic materials.

We investigated the feasibility of cryopreservation of spermatogonia and oogonia in the critically endangered cyprinid honmoroko Gnathopogon caerulescens using slow-cooling (freezing) and rapid-cooling (vitrification) methods. Initially, we examined the testicular cell toxicities and glass-forming properties of the five cryoprotectants: ethylene glycol (EG), glycerol (GC), dimethyl sulfoxide (DMSO), propylene glycol (PG), and 1,3-butylene glycol (BG), and we determined cryoprotectant concentrations that are suitable for freezing and vitrification solutions, respectively. Subsequently, we prepared the freezing solutions of EG, GC, DMSO, PG, and BG at 3, 2, 3, 2, and 2 M and vitrification solutions at 7, 6, 5, 5, and 4 M, respectively. Following the cryopreservation of the testicular cells mainly containing early-stage spermatogenic cells (e.g., spermatogonia and primary spermatocytes), cells were cultured for 7 days and immunochemically stained against germ cell marker protein Vasa. Areas occupied by Vasa-positive cells indicated that vitrification led to better survival of germ cells than the freezing method, and the best result was obtained with 5 M PG, about 50% recovery of germ cells following vitrification. In the case of ovarian cells containing oogonia and stage I, II, and IIIa oocytes, vitrification with 5 M DMSO resulted the best survival of oogonia, with equivalent cell numbers to those cultured without vitrification. The present data suggest that male and female gonial cells of the endangered species G. caerulescens can be efficiently cryopreserved using suitable cryoprotectants for spermatogonia and oogonia, respectively.

Size at maturity of fluvial white-spotted charr, Salvelinus leucomaenis, was studied in small headwater tributaries of nine rivers around the Lake Biwa water system, Japan. Threshold size at maturity in both sexes showed significant positive relationships with water discharge, indicating that smaller threshold sizes at maturity of fluvial white-spotted charr occurred in smaller habitats. These results provide a link between size at maturity and habitat size and have important implications for the management of both habitats and white-spotted charr populations.

Radical polymerization of N-isopropylacrylamide (NIPAAm) was investigated at low temperatures in the presence of both hexamethylphosphoramide (HMPA) and alkyl alcohols. Although HMPA and alkyl alcohols separately induced syndiotactic specificity in NIPAAm polymerization in toluene at low temperatures, a combination of HMPA and less bulky alkyl alcohols, such as methanol and ethanol, was found to induce isotactic specificity at −80 °C. NMR analysis of mixtures of NIPAAm, ethanol and HMPA suggested the formation of a 1:1:1 complex through O–H•••O=C and N–H•••O=P hydrogen bonding. It is believed that the steric effect of HMPA enhanced by cooperative hydrogen bonding was responsible for the combined effect of HMPA and alkyl alcohols in inducing isotactic specificity.

Group care and home-like care are two typical perspectives to discuss about the children's education at children's home. We had a survey on the understanding of the caring environment of the staff working at children's home, mainly using photoes to communicate with the surveyed staff the key concepts such as “home-like”, “ordinary” life “individuality” and “laxuary”. We found, due to the pedagogical style employed by different children's homes, following differences among the staff's understandings:1) the staff at Taisha-style children's home pointed out the existence of a serious gap between the current environment and “home-like” and “ordinary” living environment, and they wished for a more “home-like” environment;2) the staff at Shousha-style children's home evaluated highly of Shousha-style care from their observation on the way children acted but wished for even a smaller environment for better results; 3) the staff at GH concluded that it has been offering effective education resulted from the smallness of its environment.

Radical polymerizations of N-isopropylacrylamide (NIPAAm) in several solvents at low temperatures in the absence or presence of hexamethylphosphoramide (HMPA) or 3-methyl-3-pentanol (3Me3PenOH) were examined. The isotacticities of the poly(NIPAAm)s obtained in the absence of HMPA and 3Me3PenOH at lower temperatures slightly increased as the polarities of the solvents used increased. The addition of HMPA significantly induced the syndiotactic-specificity even in polar solvents such as tetrahydrofuran and acetone, although the use of the solvents having proton-donating ability, such as chloroform, prevented the induction of the syndiotactic-specificity, even if their polarities are low. In the presence of 3Me3PenOH, a good correlation between the polarities of the solvents used and the syndiotacticities of the obtained poly(NIPAAm)s was observed, and poly(NIPAAm) with r = 73% was obtained using the toluene/methylcyclohexane mixed solvent.

This report has aimed to clarify the transformation process of how of DEWKS woman to work and how to live by using the panel data. The analysis method is as follows.1)Comparison analysis of DEWKS and other lifestyles by cross tabulation2)The feature of DEWKS is analyzed by the multiple correspondence analysis.3)Data is compared with the time series, and the transformation process is analyzed.It was clarified that coexisting type DEWKS woman was able to secure the working time. It is guessed that the environment that supports the load of the woman especially in the city part is requested.

The sex ratios of the offspring of males from broods of honmoroko Gnathopogon caerulescens that displayed thermolabile sex determination (TSD), and those from eggs collected from the wild, strongly suggest that the combination of parents plays an important supplementary role in TSD in this species. The proportion of females in all broods from eight pairings of fish captured in the field decreased significantly at 30°C compared to 20°C, and one brood was entirely female at the lower temperature. These results suggest that phenotypic males (XX-males) exist in nature, probably as a result of sex change from genetic females caused by TSD. Sex ratios in relation to water temperature fall into five patterns, two of which seem to result from normal pairings of XX-females and XY-males, and from pairings of XX-males and XX-females with non-thermosensitivity. Two other patterns are thought to result from the same types of pairing, but with thermosensitivity. The last pattern, which shows male bias at both low and high temperature, is not explained only by the combination of genotypic sex determination (XX/XY) and TSD. Fluctuating temperatures close to natural conditions showed little potential to masculinize broods laid in the field between April and early June. However, the sex ratios of fish spawned in early June showed male bias at low and high temperatures. The sex determination mechanism in G. caerulescens may involve the interaction between temperature and sex-determining genetic factors, and the relative importance of each component differs with breeding season.

Functional sex reversal of all-female nigorobuna Carassius carassius grandoculis to phenotypic males was examined by immersion exposure of fry to 17-methyltestosterone (17-MT) and controlled water temperature during early development. Fry were reared in water containing differ- ent concentrations of 17-MT at 24 and 30°C for 80 days starting 20 days after hatching. Although the fish exposed to 0.1 and 1.0 mg/L 17-MT at 24°C were all male, treatment with 10.0 mg/L 17-MT resulted in 43% females. Twenty-two percent males appeared in the control treatment at 30°C but the control at 24°C was entirely female. The proportion of males in treatments exposed to 0.01- 1.0 mg/L 17-MT at 30°C was slightly lower than in the respective treatments at 24°C. These results indicate that the phenotypic expression of sex in nigorobuna is thermolabile and that sex determi- nation is under the control of genetic factors and temperature. Also, control of temperature during early development has been shown to be important for the production of all-female offspring for use as breeding stock for pond culture of fish suitable for preparation as 'funazushi'.

1998年3月から2000年11月にかけて,琵琶湖南湖周辺の10市町村の琵琶湖岸,内湖,河川,水路,池など879地点を調査し,16科42属55種(亜種を含む)の魚類を採集した。オイカワ,カワムツA型,カワムツB型,タモロコ,カマツカ,ギンブナ,アユ,トウヨシノボリなどの在来種は多くの調査地点に分布していた。一方,外来種のブルーギルやオオクチバスも多くの調査地点で採集された。分布パターンを魚種で分類するためにクラスター分析を行った結果,AからDの4つのクラスターが不明瞭ながら認められ,分布パターンと地形との間に関係が認められた。オイカワやカマツカに代表されるクラスターAとタイリクバラタナゴやメダカに代表されるクラスターBの多くは,デルタ帯,扇状地帯に広く分布するが,カワムツA型やタモロコに代表されるクラスターBの一部はデルタ帯に分布しない。その一方で,カワムツB型に代表されるクラスターCは丘陵地に分布し,ブルーギル(クラスターD)はデルタ帯に分布していた。タモロコやカワムツA型などクラスターBの一部の魚種はブルーギルの影響を強く受けているものと思われた。

We succeeded to establish cell lines from endemic fish species Honmoroko Gnathopogon caerulescens, which inhabits Lake Biwa, the third oldest lake in the world. Two cell lines designated as RMT1 and RMO1 were established from testis and ovary of G. caerulescens, respectively. These cell lines were initially cultured in Leibovitz’s L-15 medium supplemented with fetal bovine serum (FBS), fish embryo extract, epidermal growth factor, and basic fibroblast growth factor. Further addition of forskolin and β-mercaptoethanol was required to establish and maintain these cell lines for more than 60 passages. RMT1 and RMO1 cells showed fibroblast- and epithelial-like morphology, respectively. From immunocytochemical staining and gene expression patterns, RMT1 cells showed a characteristic of testicular Sertoli cells and RMO1 cells did that of ovarian theca cells. Both RMT1 and RMO1 cells multiplied well in the medium supplemented with 10 % FBS at 28 °C and their minimum population doubling times were 24.4 and 28.8 h, respectively. At the 45th passage, most of the RMT1 and RMO1 cells had a hyperploid set of chromosomes (67.3 and 96.1 %, respectively). Cells with normal diploid chromosome set were not observed. RMT1 cells were transfected with an enhanced green fluorescent protein (EGFP) expression vector and human elongation factor 1 α promoter worked efficiently to express EGFP. In addition, EGFP-expressing cell lines were also established, suggesting that the cell lines could be utilized as an in vitro monitor system (biosensor) for the evaluation of endocrine disruptors which might affect gonadal function.

食道腫瘍術後に肺合併症をきたし人工呼吸管理が長期化することはしばしば経験される.食道腫瘍症例29例を対象とし,術後1週間以上の人工呼吸管理を必要とした症例11例と1週間以内に人工呼吸から離脱できた症例18例に分け,術前,術中,術後における呼吸不全の発生に関連すると考えられる項目について比較検討した.各項目のなかで,両群間に有意の差がみられたものはリンパ節郭清の程度など手術操作に関連した項目のみであった.人工呼吸管理が長期化した症例では有意に広範囲のリンパ節郭清が行なわれており,こうした症例では術後2,3日目に肺酸素化能の低下が生じていた.食道腫瘍術後に肺合併症をきたし人工呼吸管理を長期化させる重要な要因の一つとして広範なリンパ節郭清などの手術侵襲があると考えられ,こうした手術侵襲により開胸側肺の長時間の機械的圧排による無気肺が生じ,さらに肺リンパ流が障害され肺合併症を引き起こすと考えられた.

Changes in lipid content, lipid class composition, and fatty acid composition in wild and cultur-ed biwa and amago salmon underyearlings were examined during the period of body silvering. Cultured biwa salmon showed slight changes in these components of the muscle during body sil-vering. Although cultured amago salmon parr showed seasonal fluctuations in the components, the smolts did not show definite difference as compared with the parr in early smolting season. On the other hand, wild biwa salmon displayed a marked difference in the lipid class composition and fatty acid composition between the parr in the river and the silvery fish in the lake. In silvering biwa salmon, depletion of 16:1, 18:2n6, 18:3n3 and increase in 22:6n3 of nonpolar lipids were observed, the pattern being similar to the marine fish lipid. Since no change was seen in cultured biwa salmon, differences in the lipid class and fatty acid compositions between the parr in the river and the silvery fish in the lake in wild biwa salmon seem to be related to differences in their feeding habit and/or in swimming activity.

Downstream migratory behavior, plasma T4 concentrations and histological changes in the thyroid gland of biwa salmon underyearlings were examined during late spring and early summer for three consecutive years. The downstream migration was observed specifically when the flux of the river increased following rainfall. A close correlation was seen between the number of migrants and the rate of flux increase of the river. Plasma T4 levels of the fry caught in the river were variable, and no correlation was seen between the plasma T4 levels in the fish remaining in the river and lunar phase, rainfall, water flux or water temperature. However, significantly higher T4 concentrations were observed in the fish during downstream migration when compared with those in the fish remaining in the river and postmigrants in the lake. The mean epithelial height of the thyroid folliciles was greatest in the underyearling in May, shortly before the onset of the migratory season. The thyroidal activity of the migrants in late May and June tended to decrease and postmigrants in the lake had inactive thyroid. These results suggest that the rainfall or the associated changes in turbidity and flux is one of the initiators of the migratory behavior in biwa salmon, and also that thyroid hormone is involved directly or indirectly in downstream movement.