000			04481nas|a2200445 i 4500
005			20260817172042.0
008			040621s2003 th uzm rtt 00| a1eng d
035			_a.b11923830
099		9	_aAIT Diss. no. EV-03-3
100	0		_aPeerakarn Banjerdkij
245	1	0	_aCadmium ion induced oxidative stress responses of Xanthomonas campestris pv. phaseoli
260			_aPathum Thani, Thailand : _bAsian Institute of Technology, _c2003
300			_a127 p.
490	1		_aDissertation ; _vno. EV-03-3
500			_aA dissertation submitted in partial fulfillment of the requirements:· for the degree of Doctor of Technical Science Inter-University Program on Environmental Toxicology, Technology and Management
520			_aCadmium (Cd) and zinc (Zn) are important environmental pollutants contaminated in crop fields where phosphate fertilizers have been abundantly used and from industrial sources. The responses of Xanthomonas campestris, a soil and plant bacterial pathogen, against the exposure of Cd and Zn were investigated. Pretreatment of X campestris with sub-lethal concentrations of Cd induced adaptive protection against subsequent exposure to lethal doses of Cd. Moreover, Cd-induced cells also showed cross-resistance to lethal concentrations of Zn. These induced protections required newly synthesized proteins. Unexpectedly, Zn-induced cells did not exhibit adaptive protection against lethal concentrations of Zn or Cd. These data suggested that the increased resistance to Cd and Zn killing probably involved other protective mechanisms in addition to ion efflux. The effects of Cd and Zn on oxidative stress response in X campestris were investigated. Pretreatment of X campestris with inducing concentration of Cd stimulates onset of cross- protection against subsequent killing treatments with H20 2 and tert-Butyl hydroperoxide (tBOOH) but not with menadione (MD). Cross-resistance to H20 2 was fully dependent on OxyR, a peroxide sensor and transcription regulator, as shown by the completely loss of induced protection in the oxyR mutant pretreated cells. Induced resistance against tBOOH killing was only partially inhibited both in the oxyR and ohrR mutant suggests that these genes had crucial roles in induced protection to tBOOH. However, Cd induced cells of the oxyR and ohrR double mutant still retain partial resistance to tBOOH suggests the existence of other mechanisms involving in organic hydroperoxide protection. Exposure of exponential bacterial cultures to inducing concentration of Cd elevated the expression of various oxidative stress scavenging enzymes both in OxyR and OhrR regulons including alkyl hydroperoxide reductase (AhpC), monofunctional catalase (KatA) and organic hydroperoxide resistance (Ohr). The data elucidate that accumulated Cd in the environment could alter the responses against oxidative stress in soil and pathogenic bacteria. As a consequence, this alteration may affect plant/ microbe interaction leading to change in bacterial pathogenicity.
502			_aThesis (Ph.D.) - Asian Institute of Technology, 2003
650		0	_aCadmium
650		0	_aXanthomonas campestris
700	0		_aSkorn Mongkolsuk, _eChairperson
700	0		_aPreeda Pakpian, _eExamination Committee
700	0		_aSuvit Loprasert, _eExamination committee
700	0		_aPaiboon Vattanaviboon, _eExamination committee
700	0		_aChongrak Polprasert, _eExamination Committee
700	1		_aSaovanee C. Dharmsthiti, _eExamination committee
710	2		_aPost-Graduate Education, _eScholarship donor
710	2		_aTraining and Research Program in Environmental Science, Technology and Management under Higher Education Development Project of the Ministry of University Affairs, _eScholarship donor
810	2		_aAsian Institute of Technology. _tDissertation ; _vno. EV-03-3
856			_3Full-Text _u http://203.159.5.9/ait-thesis/detail.php?q=B07636
907			_a.b11923830 _bmnait _cu
902			_a240417
998			_b0 _c040430 _dm _ea _fu _g0
945			_lmnait
945			_lmnarc
942			_c22
942			_c40
909			_aBarcode : 30050120726053 _bCREATED : 2012-08-16 _cRECORD # : i12686827 _dLPATRON : 1015494 _eLCHKIN : 2015-12-01 _f# RENEWALS : 0 _g# OVERDUE : 0 _hIUSE3 : 0 _iTOT CHKOUT : 1 _jTOT RENEW : 0
909			_aBarcode : 30050160004601 _bCREATED : 2016-02-02 _cRECORD # : i12876628 _dLPATRON : 0 _eLCHKIN : - _f# RENEWALS : 0 _g# OVERDUE : 0 _hIUSE3 : 0 _iTOT CHKOUT : 0 _jTOT RENEW : 0
999			_c14606 _d14606