Purification and Characterization of 55K, a Major Cytoskeletal Protein from Vibrio cholerae O1

コレラ菌をTCG寒天培地で培養し,そのフレンチ・プレス破砕後の可溶性画分からセファデックスG-100及びDEAE-セファデックスA-50を用いて,分子量55,000の主要細胞骨格蛋白を精製した.この蛋白はSDS-PAGE上では単一バンドであるが,SDS-urea-PAGE及び等電点電気泳動では2本のバンドを示した.この蛋白のアミノ酸組成はチューブリンのそれと類似していた.55K蛋白は,Mg++,EGTAの存在下で容易にホモジナイザーで抽出されるが,細胞内の極及び細胞質に存在している事が証明された。Taxolは55K蛋白の極及び細胞質への局在を安定化するのに有効であった.抗チューブリン抗体はコレラ菌及びNon-O1コレラ菌の55K蛋白を認識した.この55K蛋白はコレラ菌のみならず,ビブリオ科の株に共通に認められた.55K蛋白より構成されていると思われる4量体が,コレラ菌表層より単離された.以上の事から,コレラ菌55K蛋白は,真核細胞の細胞骨格蛋白のチューブリンと近縁の蛋白と思われ,原核細胞の分裂機構を解明する上で有効な構造蛋白と思われる.A major cytoskeletal protein of MW 55K was purified from the soluble fraction of French-pressed cells of Vibrio cholerae O1 cultured on TCG agar (Ehara et al., 1986) by gel filtration through Sephadex G-100 and ion-exchange chromatography with DEAE-Sephadex A-50. This protein showed a doublet band on SDS-urea-PAGE and isoelectric focusing, although a single band was seen on SDS-PAGE. The amino acid composition of the 55K protein had a molar ratio similar to that of tubulin. Although the 55K protein was easily extracted from vibrio cells by homogenization in the presence of Mg++ and EGTA, it was found to be localized around cell poles and in the cytoplasm. Taxol was effective in stabilizing the 55K protein around the cell poles and in the cytoplasm. Anti-tubulin antiserum recognized the 55K doublet band of a non-O1 Vibrio cholerae, as well as the 55K protein of Vibrio cholerae. The 55K protein was present commonly among the strains of Family Vibrionaceae. Tetramers presumably composed of the 55K protein were isolated from the cell surface

Epidemiological Observation of Cholera in Rural Kenya in 1983

Homa Bay地区病院のコレラ検査室で調べられた約17,000検体のうち再検例を除く,1,301検体が陽性者で,うち入院者788名,健康保菌者513名であった.コレラ感染率は13～19歳の男性に最も少なく,15～39歳の女性に最も高かった.流行は3月と7月にみられ,いずれも乾期の終わりで雨期に入る直前であった.月別・年齢別にみると,3月は20～39歳,7月は13～19歳に最も多くみられた.地区別にみると,KarachuonyoとKanyadaに患者は集中していた.致命率は9%と高く,発展途上国のもつ,共通の背景があるように思われた.家族内感染は161例に認められ,他は散発例であった.薬剤感受性については,1982年に多剤耐性株が若干認められたが,1983年のほとんどが耐性株であり,O/129にも耐性を示した.耐生パターンはタンザニア分離株のそれとも異なっており,コレラ菌の土着性を思わせた.この疫学調査で最も重要なことはコレラは再感染がほとんど認められないということであった。即ち,有効なワクチン開発の可能性が大であることを示唆している.More than 17,000 rectal swab specimens were examined for Vibrio cholerae Ol at Cholera Laboratory in Homa Bay District Hospital. Out of these specimens, 1,301 cases were bacteriologically cholera-positive excluding repeated specimens. The number of admitted cases and healthy carriers were 788 and 513 respectively. Infection rate of cholera was lowest in the age-group, 13-19 of male. It was highest in female of childbearing age-group (15-39). Monthly variation of cholera-positive cases showed two peaks in March and July, closely correlated with the dry season. Monthly variation of cholera by age-group also showed two peaks in March and July. The former peak was formed by the age-group of 20-39 and the latter was by 13-19. High infection rate was found in Karachuonyo and Kanyada. The mortality of the admitted cases was 9%. One hundred and sixty-one cases were thought to be caused by family contacts, however most of the others were sporadic cases. Tetracycline resistant strains were isolated in 1982 even in Kenya, though the number was small. Most of the strains isolated in 1983 were resistant to multiple antimicrobial agents as well as O/129 which is a vibriostatic agent

Perpetuated Human-Wildlife Wars: A Case Study of the Marauding Elephants in Mbuvori Small Scale Farms, Embu, Kenya

This research was prompted by increasing cases of damage by elephants reported in media and frequent public demonstrations by small scale farmers adjacent to Mt. Kenya forest. A sociological survey was conducted in Mbuvori a sub-location in Embu District to examine types and extent of damage; effectiveness of conflict management strategies and people’s attitudes towards elephants. Data was analyzed using the Statistical Package for Social Science (SPSS). The conflicts have a great negative impact on the community’s welfare. Management strategies are ineffective and are not dictated by people’s attitudes. Legislation that considers the interest of locals and goals of sustainable conservation should be enacted.Keywords: Household, conflicts, management, attitude

A Study on Enterotoxigenic Escherichia coli Infection in Kenya

ケニア国においてモンバサ市の小児下痢患者と農村部(KwaleとSouth Nyanza)の健康住民を対象に毒素原性大腸菌(ETEC)の感染状況を調査した. 782大の下痢患者のうち47例(6.0%)からETECが分離され,病原性大腸菌(EPEC),カンピロバクター・ジェジュニに次いで三番目に多い腸管病原菌であった.うち24例は耐熱性毒素(ST)産生株, 21例は易熱性毒素(LT)産生株,残る2例は両毒素産生株によるものであった.またETEC感染例のうち10例からは同時に他の腸管病原菌も分離された.一方, 196人と468大計664大の健康住民からは6例と14例計20例(3.0%)からETECが検出され, EPEC 12.8%に次ぐものであった.そのうち7例はLT産生株, 12例がST産生株,残り1例は両毒素産生株の保菌者であった.ケニアにおいてもETECは小児の下痢症原因菌として重要であり,またその健康人保菌者も存在することが明らかとなった.The existence of enterotoxigenic Escherichia coli (ETEC) was studied on children with diarrhea in Mombasa and healthy inhabitants in two rural areas of Kenya in 1983. ETEC which was isolated from 6.0 per cent of rectal swabs (47/782) among the diarrheal children, was the thirdly predominant enteropathogen following enteropathogenic E. coli (EPEC) and Campylobacter jejuni. Out of 47 ETEC positive cases, heat labile enterotoxin (LT) and heat stable enterotoxin (ST) were detected in 21 and 24 cases respectively and producers of both toxins were proved in two cases. Ten out of 47 cases were also infected with other enteropathogens. On the other hand, among 664 healthy villagers 20(3.0%) carried ETEC, secondly noted pathogens following EPEC. Seven and 12 ETEC carriers were infested by LT and ST producers respectively, and only one case carried ETEC producing both oxins. This study clearly demonstrated that EXEC played a significant role as one of the leading agents of diarrheal children and carriers among healthy individuals in Kenya

Biochar helps enhance maize productivity and reduce greenhouse gas emissions under balanced fertilization in a rainfed low fertility inceptisol

Maize production plays an important role in global food security, especially in arid and poor-soil regions. Its production is also increasing in China in terms of both planting area and yield. However, maize productivity in rainfed croplands is constrained by low soil fertility and moisture insufficiency. To increase the maize yield, local farmers use NPK fertilizer. However, the fertilization regime (CF) they practice is unbalanced with too much nitrogen in proportion to both phosphorus and potassium, which has led to low fertilizer use efficiency and excessive greenhouse gases emissions. A two-year field experiment was conducted to assess whether a high yielding but low greenhouse gases emission system could be developed by the combination of balanced fertilization (BF) and biochar amendment in a rainfed farmland located in the Northern region of China. Biochar was applied at rates of 0, 20, and 40t/ha. Results show that BF and biochar increased maize yield and partial nutrient productivity and decreased nitrous oxide (N2O) emission. Under BF the maize yield was 23.7% greater than under CF. N2O emissions under BF were less than half that under CF due to a reduced N fertilizer application rate. Biochar amendment decreased N2O by more than 31% under CF, while it had no effect on N2O emissions under BF. Thus BF was effective at maintaining a high maize yield and reducing greenhouse gases emissions. If combined with biochar amendment, BF would be a good way of sustaining low carbon agriculture in rainfed areas

Enteropathogenic Escherichia coli (EPEC) Infection in Kenya

病原性大腸菌(EPEC)の保菌者の動態を把握するため,Kwale地区の住民約400人から約3ヵ月間隔で3回,検体(Rectal swab)を収集し,菌検索を行った.各検体からE. coliを3 colonyずつ拾って市販のEPEC抗血清(デンカ生研)による凝集で,型別を行った.毎回の本菌陽性率は同程度で約20%であった.そのうち毎回陽性であったのは1例のみで,2回陽性は19例であったが,いずれも異なった血清型を示していた.即ち,同一血清型株の再感染は認められず,病原性大腸菌の場合にもlong term immunityを考慮する必要があることを示唆するものとみられた.sample提供者は全て健康であった.また,Cholera survey, C. jejuni survey等で集めたE. coliも全て凝集を行い,約2,000人からのデータをまとめてEPECの保菌率,型別,ETEC検出率,性差,年齢差,地域差,健康者と下痢患者間の検出率の相異などに検討を加えた結果,いずれの場合にも感染率に有意の差は認められなかった.About two thousands of rectal swab-specimens were examined for enteropathogenic Escherichia coli (EPEC) in rural area in Kenya in 1983 by using 28 of monovalent antisera which were commercially available. According to the results obtained, there was no significant difference in the isolation rate of EPEC strains (about 20%) between diarrheal patients and healthy individuals. No marked difference was also observed in the isolation rate by age-group as well as by sex. The most dominantly isolated strain of EPEC was O27: K+ which is a well known enterotoxigenic Escherichia coli (ETEC). Most of EPEC strains isolated were identified as ETEC and some were enteroinvasive Escherichia coli (EIEC) by serotyping alone. In the three surveys with 2-3 months interval carried out for the fixed populations, the same serotype as found in the former survey was not isolated from the same individual. Although nineteen cases showed EPEC positive more than twice during the surveys. The isolation rate of EPEC in food-handlers working at the hotels in the South Coast was 20%, although they were healthy without diarrhea