Publications by authors named "Udaka H"

Terrestrial molluscs living in temperate and polar environments must contend with cold winter temperatures. However, the physiological mechanisms underlying the survival of terrestrial molluscs in cold environments and the strategies employed by them are poorly understood. Here we investigated the cold tolerance of Ambigolimax valentianus, an invasive, terrestrial slug that has established populations in Japan, Canada, and Europe.

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We established a knockout strain of a clock gene, (), by using TALEN in a bivoltine strain (Kosetsu) of (Insecta, Lepidoptera), and examined the effect of knockout on the circadian rhythm and photoperiodism. The generated knockout allele was considered to be null, because a new stop codon was present in the insertion allele. The wild type (Kosetsu) showed clear circadian rhythms in eclosion and hatching, whereas the knockout strain showed arrhythmic eclosion and hatching under constant darkness.

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Many insect species use photoperiod as a cue for induction of seasonal responses, including seasonal polyphenism. Although most aphid species viviparously produce parthenogenetic and sexual morphs under long and short days, respectively, a seasonal timer suppresses the sexual morph production over several successive generations during a few months following hatching of a sexually produced diapause egg. To reveal the relative influences of photoperiod and the seasonal timer on the reproductive polyphenism at the gene expression level, we performed RNA sequencing-based transcriptome analyses in the pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae).

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In Lepidoptera, the roles of period ( per) and the negative feedback involving this gene in circadian rhythm are controversial. In the present study, we established a per knockout strain using TALEN in Bombyx mori, and compared eclosion and hatching rhythms between the per-knockout and wild-type strains to examine whether per is actually involved in these rhythms. The generated per knockout allele was considered null, because it encoded an extensively truncated form of PERIOD (198 aa due to a 64-bp deletion in exon 7, in contrast to 1113 aa in the wild-type protein).

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Conjugates of semiconductor quantum dots (QDs) and antibodies have emerged as a promising bioprobes due to their great combination of QD's efficient fluorescence and the high specificity of antigen-antibody reactions. For further developments in this field, it is essential to understand the molecular conformation of the QD-antibody conjugates at the single-molecule scale. Here, we report on the direct imaging of QD-antibody conjugates at the single-molecule scale by using high-speed atomic force microscopy (HS-AFM).

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The ability to survive and reproduce after cold exposure is important in all kingdoms of life. However, even in a sophisticated genetic model system like , few genes have been identified as functioning in cold tolerance. The accumulation of the () gene transcript increases after cold exposure, making it a good candidate for a gene that has a role in cold tolerance.

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An approach similar to the enzyme-linked immunosorbent assay (ELISA), with the advantage of saving time and effort but exhibiting high performance, was developed using orientation-directed half-part antibodies immobilized on CdSe/ZnS quantum dots. ELISA is a widely accepted assay used to detect the presence of a target substance. However, it takes time to quantify the target with specificity and sensitivity owing to signal amplification.

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Background: Cold tolerance is a key determinant of temperate insect distribution and performance. Chill-susceptible insects lose ion and water homeostasis during cold exposure, but prior cold acclimation improves both cold tolerance and defense of homeostasis. The mechanisms underlying these processes are mostly unknown; cold acclimation is thought to enhance ion transport in the cold and/or prevent leak of water and ions.

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Cold tolerance is a key determinant of insect distribution and abundance, and thermal acclimation can strongly influence organismal stress tolerance phenotypes, particularly in small ectotherms like Drosophila. However, there is limited understanding of the molecular and biochemical mechanisms that confer such impressive plasticity. Here, we use high-throughput mRNA sequencing (RNA-seq) and liquid chromatography - mass spectrometry (LC-MS) to compare the transcriptomes and metabolomes of D.

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Conjugates of semiconductor quantum dots (QDs) and organic dyes have been receiving attention as fluorescence biological sensing materials. In designing such sensors, a most important parameter is the number of organic-dye molecules that conjugate to a QD. If a precise separation method was developed, it might be possible to control conjugation without knowing the exact number of conjugated dye molecules per QD.

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The acorn weevil, Curculio glandium, is a widespread predator of acorns in eastern North America that overwinters in the soil as a larva. It is possible that low temperatures limit its northern geographic range, so we determined the cold tolerance strategy, seasonal variation in cold tolerance, and explored the physiological plasticity of overwintering larvae. Weevil larvae were collected from acorns of red and bur oak from Pelee Island, southwestern Ontario in fall 2010 and 2011.

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Frost (Fst) is a candidate gene associated with the response to cold in Drosophila melanogaster because Fst mRNA accumulation increases during recovery from low temperature exposure. We investigated the contribution of Fst expression to chill-coma recovery time, acute cold tolerance and rapid cold hardening (RCH) in adult D. melanogaster by knocking down Fst mRNA expression using GAL4/UAS-mediated RNA interference.

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The terrestrial slug Lehmannia valentiana was first recorded in Japan in the late 1950s and is now distributed throughout the country. Previous studies have revealed that in Osaka, southwestern Japan, L. valentiana reproduces from November to April.

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In this study, we investigated the physiological mechanisms underlying temperature tolerance using Drosophila melanogaster lines with rapid, intermediate, or slow recovery from heat or chill coma that were established by artificial selection or by free recombination without selection. Specifically, we focused on the relationships among their recovery from heat or chill coma, survival after severe heat or cold, and survival enhanced by rapid cold hardening (RCH) or heat hardening. The recovery time from heat coma was not related to the survival rate after severe heat.

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We investigated the fatty acid compositions of phospholipids in Drosophila melanogaster lines showing rapid (CR), intermediate (CTL), or slow (CS) recovery from chill coma, which were established by artificial selection or by free recombination without selection. Compared to CTL, CS showed a low composition of dienoic acids and a small number of double bonds in the fatty acids. The ratio of unsaturated fatty acids and saturated fatty acids (UFAs/SFAs) was significantly lower in CS than in CTL.

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Terrestrial slugs (Lehmannia valentiana) collected from a field in Osaka, southwestern Japan, were reared under long-day (16-h light and 8-h darkness, LD 16:8) or short-day conditions (LD 12:12) at 15, 20, or 25 degrees C for 60 days. Slugs reared under short-day conditions were heavier than those reared under long-day conditions; however, slugs reared at 15 degrees C gained more weight regardless of the photoperiodic condition. Gonads were significantly heavier under short-day conditions than under long-day conditions, and oogenesis and spermatogenesis were also induced under short-day conditions.

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We report a case of undifferentiated (embryonal) sarcoma (USL) of the liver arising in a 5-year-old girl. She had abdominal pain and distension after a blow to her abdomen. Exploratory laparotomy disclosed a large tumor arising from left lobe of the liver, which showed a typical gross and microscopic appearance of USL.

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Forty patients with choledochal cysts, 17 children and 23 adults, were treated by cyst excision in this institution (1972 to 1982). Histochemical and immunohistochemical studies were performed on tissue from the walls of these 40 cysts. The type and degree of histologic changes observed were found to correlate with patient age at time of cyst excision.

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A nationwide survey of cases of congenital dilatation of the biliary duct was conducted to obtain the data on cases of congenital dilation of the biliary duct in Japan between 1972 and 1982. A total of 645 cases were surveyed. An anomalous arrangement of the pancreaticobiliary ductal system (AAPABIDS) was associated with congenital dilatation of the biliary duct in 90.

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Histochemical and immunohistochemical studies on 47 consecutive specimens excised for choledochal cyst were performed to clarify possible metaplastic changes of the biliary duct in relation to carcinogenesis. An anomalous arrangement of the pancreaticobiliary ductal system was observed in all 39 cases examined. Among the 47 patients, 5 (10.

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A nationwide survey of cases of choledochal cyst was conducted to obtain the data on cases of choledochal cyst in Japan between 1972 and 1982. A total of 645 cases in 73 institutions, including 52 cases from this hospital, were surveyed. Choledochal cyst was associated with an anomalous arrangement of the pancreaticobiliary ductal system in 90.

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