title: Plasma esterases in the tegu lizard Tupinambis merianae (Reptilia, Teiidae): impact of developmental stage, sex, and organophosphorus in vitro exposure.
abstract: OBJECTIVE
  In this study, we determined normal serum butyrylcholinesterase (BChE) and carboxylesterase (CbE) activities in Tupinambis merianae in order to obtain reference values for organophosphorus pesticide monitoring.
  
  
  METHODS
  Forty-two T. merianae individuals were grouped by sex and size to identify potential differences in their enzyme levels to allow for proper representation of normal values for females, males, juveniles, and hatchlings. Mean CbE was determined using two model substrates: alpha-naphtylacetate (α-NA) and p-nitrophenyl valerate (4-NPV). BChE and CbE sensitivity to malaoxon (Mx) was also evaluated as well as the possibility of BChE reactivation with pyridine-2-aldoxime methochloride (2-PAM).
  
  
  RESULTS
  Mean adult females' BChE was significantly higher than adult males, juveniles, and hatchlings. No significant differences were found between groups regarding CbE. CbE (4-NPV) activity showed slightly negative correlation with lizard snout-vent length, while BChE and CbE (α-NA) showed no correlation with body size. Apparent IC(50) values for BChE and CbE (α-NA) suggested different sensitivities among groups. CbE (4-NPV) could not be inhibited. All Mx-inhibited groups treated with 2-PAM in a final concentration of 2.8 mM showed clear signs of reactivation.
  
  
  CONCLUSIONS
  In conclusion, the results demonstrate that (1) plasma esterase activity did not vary with age and sex, except for BChE activity, and (2) because biological and environmental variables could be confounding factors in the response of plasma cholinesterases, complementary biomarkers like CbE inhibition and oxime-induced reactivation of esterases are strongly recommended.
authors: Faculty of Biochemistry and Biological Sciences-FBCB-UNL, Santa Fe, Argentina. bassoagustin@gmail.com
authors: Agustín
authors: A
authors: Basso
authors: Andrés M
authors: AM
authors: Attademo
authors: Rafael C
authors: RC
authors: Lajmanovich
authors: Paola M
authors: PM
authors: Peltzer
authors: Celina
authors: C
authors: Junges
authors: Mariana C
authors: MC
authors: Cabagna
authors: Gabriela S
authors: GS
authors: Fiorenza
authors: Juan Carlos
authors: JC
authors: Sanchez-Hernandez
mesh_terms: D000818:Animals; D001717:Birds / Q000097:blood / Q000145:classification / Q000254:growth & development / Q000502:physiology; D002091:Butyrylcholinesterase / Q000097:blood*; D043182:Carboxylesterase / Q000097:blood*; D004781:Environmental Exposure / Q000032:analysis*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D008116:Lizards / Q000097:blood / Q000145:classification / Q000254:growth & development / Q000502:physiology*; D008294:Malathion / Q000031:analogs & derivatives* / Q000633:toxicity; D008297:Male; D009943:Organophosphorus Compounds / Q000633:toxicity*; D010575:Pesticides / Q000633:toxicity*; D012727:Sex Characteristics
chemical_list: D009943:Organophosphorus Compounds; D010575:Pesticides; C100082:malaoxon; D043182:Carboxylesterase; D002091:Butyrylcholinesterase; D008294:Malathion