title: Persistence of cadmium-induced adaptive response to genotoxicity of maleic hydrazide and methyl mercuric chloride in root meristem cells of Allium cepa L.: differential inhibition by cycloheximide and buthionine sulfoximine.
abstract: With an objective to determine the period of persistence of the metal-induced adaptive response to chemical mutagens and heavy metals, growing root meristems of Allium cepa were conditioned by cadmium sulfate (CdSO4), 4 x 10(-7) and 4 x 10(-6) M for 1 h and subsequently challenged by maleic hydrazide (MH), 5 x 10(-3) M or methyl mercuric chloride (MMCl), 1.26 x 10(-6) M for 3 h at different time intervals ranging from a few minutes to several hours following the conditioning dose. Root meristems, fixed at regular intervals during recovery from 6 to 48 h, were cytologically analysed for cells with micronuclei (MNC). The adaptive responses to MH and MMCl were observed as early as 5 min after the Cd-conditioning that persisted for at least 48 h. Metabolic inhibitors, cycloheximide (CH). 10(-7) M and buthionine sulfoximine (BSO), 10(-4) M administered either prior to or simultaneous with Cd-conditioning effectively prevented the adaptive response to MH. Whereas BSO, an inhibitor of phytochelatin synthesis, prevented the adaptive responses from 15 min to 8 h after the conditioning dose, CH an inhibitor of cytoplasmic protein synthesis prevented the same from 6 to 48 h. The findings underscored the differential roles of phytochelatins and proteins underlying the foregone metallo-adaptive response.
authors.affiliation: Department of Botany, Berhampur University, Orissa, India.
authors.forename: K K
authors.initials: KK
authors.lastname: Panda
authors.forename: J
authors.initials: J
authors.lastname: Patra
authors.forename: B B
authors.initials: BB
authors.lastname: Panda
mesh_terms: D000064:Acclimatization; D000490:Allium / Q000166:cytology / Q000187:drug effects / Q000235:genetics*; D016587:Antimutagenic Agents / Q000494:pharmacology*; D019187:Cadmium Compounds / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008300:Maleic Hydrazide / Q000633:toxicity*; D018519:Meristem; D008767:Methylmercury Compounds / Q000633:toxicity*; D015162:Micronucleus Tests; D009153:Mutagens / Q000633:toxicity*; D013431:Sulfates / Q000494:pharmacology*
chemical_list: D016587:Antimutagenic Agents; D019187:Cadmium Compounds; D008767:Methylmercury Compounds; D009153:Mutagens; D013431:Sulfates; C037123:cadmium sulfate; C004925:methylmercuric chloride; D008300:Maleic Hydrazide