58 research outputs found

    A toxin hunter in the microworld of bacteria: a project on novel inhibitors against bacterial AB5 toxins

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    [要旨] 病原性細菌が産生する蛋白性のAB5型トキシンは1個のAサブユニットと5個のBサブユニットから構成される外毒素である。両サブユニットはそれぞれ特徴的な役割を持ち,互いに巧妙に機能分担をして一つのトキシンを形成している。Aサブユニットは主に毒性に直接関与する特異的な酵素活性を有する。一方,Bサブユニットは標的細胞のレセプターに対する結合能を有し,AB5型トキシンを標的細胞に吸着させる。ここでは毒性が全く異なるAB5型トキシンとして,コレラ菌が産生するコレラトキシン(CT),腸管出血性大腸菌が産生する志賀様トキシン(Stx),及び志賀トキシン産生大腸菌が産生するサブチラーゼサイトトキシン(SubAB)の3種類に関して,その作用メカニズムに着目した毒性を抑制する阻害因子の探索などの研究を紹介する。これらの3種類のAB5型トキシンに着目した理由は,それぞれのトキシンを産生する病原菌による感染症が世界的に流行し,社会問題となっているからである。つまり,コレラ菌は依然として発展途上国で大きな問題であり,腸管出血性大腸菌のO157:H7による集団食中毒は我国でも依然として多い。さらに21世紀になり,血清型がO157:H7以外の腸管出血性大腸菌による集団食中毒が世界的に急増しているためである。いずれも抗生物質を使用した後の残留トキシンによる病態悪化が指摘されており,トキシンを効率よく無毒化する事が急務である。[SUMMARY] Bacterial AB5 toxins are proteins, produced by pathogenic bacteria including of Vibrio cholerae, Shigella dysenteriae, and enterohaemorrhagic Escherichia coli, which are usually released into the extracellular medium and cause disease by killing or altering the metabolism of target eukaryotic cells. The toxins are usually composed of one A subunit(a toxic domain) and five B subunits(a receptor-binding domain). This article overviews the characteristics and mode of actions of AB5 toxins including cholera toxin, Shiga-like toxin, and subtilase cytotoxin, and highlights a project on the novel inhibitors against these bacterial AB5 toxins

    Additional file 7: of Genetic composition of captive panda population

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    Living wild founders without descendants in the captive population. (PDF 17 kb

    Additional file 5: of Genetic composition of captive panda population

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    Genetic composition and inbreeding coefficients of hypothetical offspring of the 1630 mating pairs free of pedigree and hidden inbreeding. (XLSX 463 kb

    Exposure to Odors of Rivals Enhances Sexual Motivation in Male Giant Pandas

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    <div><p>Males will alter their mating behavior to cope with the presence of their competitors. Even exposure to odors from potential competitors can greatly increase male ejaculate expenditure in a variety of animals including insects, fishes, birds and rodents. Major efforts have been made to examine males' plastic responses to sperm competition and its fitness benefits. However, the effects of competitor absence on male's sexual motivation and behaviors remain unclear, which has been proposed to be one of the causes for the poor sexual performance of some captive mammals. This study revealed that sexual motivation can be greatly enhanced in captive male giant pandas (<i>Ailuropoda melanoleuca</i>) by exposure to chemosensory cues from either one or three conspecifics males. It had been shown that potential rivals' odors increased males' chemosensory investigation behavior, as well as their observing, following and sniffing behaviors towards estrous females. Behaviors changed regardless of the number of rivals (one or three). Our results demonstrate the effects of potential competition on male giant pandas' sexual motivation and behavioral coping strategy. We anticipate that our research will provide a fresh insight into the mechanisms underlying poor sexual performance in male captive mammals, and valuable information for the practical management and <i>ex situ</i> conservation of endangered species.</p></div

    Temporal patterns of behavior in male pandas.

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    <p>A)Chemosensory investigation and female-oriented behavior (including observing, following, and sniffing the females; B) in male giant pandas that were exposed to odor sources from either a single male (SM) or multiple males (MM), or to their own fecal samples (Control) within 30 minutes of the observation period. Data are shown as mean – SE; * indicates a significant difference from the control.</p

    Behaviors of male pandas in different treatment groups.

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    <p>Males exposed to odor sources from either a single male (SM) or multiple males (MM) spent more time on A) chemosensory investigation as well as on B) observing and C) following neighboring females than Control males, and MM males D)sniffed females more than Control males. E) No differences between groups were found in the frequency of other behaviors including urination, AGS scent-marking, body rubbing, bleating, and foot scraping. Data are mean + SE, bars with different letters differ significantly from each other.</p

    Kinetic expression of chemokines in rat vascular smooth muscle cells.

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    <p>Total RNA was extracted from rat smooth vascular muscle cells treated with IFN-γ, LPS, or IFN-γ plus LPS for different times as indicated and reverse transcribed into cDNA for measurement of CCL5 (A), IP-10 (B) and MCP-1 (C) expression by qRT-PCR. Data were normalized relative to GAPDH mRNA expression levels in each respective sample and further normalized to the results from the un-treated group, which was set as 1.</p
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