title: LDH-B enzyme expression: the mechanisms of altered gene expression in acclimation and evolutionary adaptation.
abstract: The temperature-dependent expression of lactate dehydrogenase-B (LDH-B) was compared between two environmentally distinct populations of Fundulus heteroclitus acclimated to 10 degrees C and 20 degrees C. The variability in LDH-B protein expression both within and between populations is consistent with a model of thermal compensation. The northern population from the colder environment expresses a twofold greater amount of LDH-B protein than the warmer southern population at both acclimation temperatures. Correspondingly, both populations have 1.3-fold greater levels of the enzyme at an acclimation temperature of 10 degrees C in comparison to 20 degrees C. In 20 degrees C-acclimated individuals there is a similar twofold difference between populations for LDH-B mRNA concentrations, and LDH-B protein and mRNA are highly correlated (r = 0.81). After acclimation to 10 degrees C, this difference between populations is not seen and in the northern population there is no relationship between LDH-B mRNA and protein levels. Thus the molecular mechanism regulating LDH-B enzyme expression changes in response to temperature acclimation and is different between populations.
authors.affiliation: Department of Organismal Biology and Anatomy, University of Chicago, Illinois 60637.
authors.forename: J A
authors.initials: JA
authors.lastname: Segal
authors.forename: D L
authors.initials: DL
authors.lastname: Crawford
mesh_terms: D000064:Acclimatization; D000222:Adaptation, Physiological; D000704:Analysis of Variance; D000818:Animals; D005075:Biological Evolution; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes; D007695:Killifishes / Q000502:physiology*; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D012044:Regression Analysis; D013696:Temperature
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D007770:L-Lactate Dehydrogenase