1. 3,3',4,4'-Tetrachlorobiphenyl oxidation in fish, bird and reptile species: relationship to cytochrome P450 1A inactivation and reactive oxygen production
J J Schlezinger, J Keller, L A Verbrugge, J J Stegeman Comp Biochem Physiol C Toxicol Pharmacol. 2000 Mar;125(3):273-86. doi: 10.1016/s0742-8413(99)00112-7.
Previously we showed that the polychlorinated biphenyl 3,3',4,4'-tetrachlorobiphenyl (TCB) caused a release of reactive oxygen species (ROS) from cytochrome P450 1A (CYP1A) of the fish scup (Stenotomus chrysops), and from rat and human CYP1A1. This was linked to a TCB- and NADPH-dependent oxidative inactivation of the enzyme, which in scup and rat was inversely related to the rates of TCB oxidation. We examined the relationship between rates of TCB oxidation, CYP1A inactivation and ROS production in liver microsomes from additional vertebrate species, including skate (Raja erinacea), eel (Anguilla rostrata), killifish (Fundulus heteroclitus), winter flounder (Pleuronectes americanus), chicken (Gallus domesticus), cormorant (Phalacrocorax auritus), gull (Larus argentatus), and turtle (Chrysemys picta picta). TCB oxidation rates were induced in all fish and birds treated with aryl hydrocarbon receptor agonists. Induced rates of TCB oxidation were <1 pmol/min/mg microsomal protein in all fish, and 6-14 pmol/min/mg in the birds. In all species but one, TCB oxidation rates correlated positively with EROD rates, indicating likely involvement of CYP1A in TCB oxidation. Incubation of liver microsomes of most species with TCB+NADPH resulted in an immediate (TCB-dependent) inhibition of EROD, and a progressive loss of EROD capacity, indicating an oxidative inactivation of CYP1A like that in scup. NADPH stimulated production of ROS (H(2)O(2) and/or O(2)(-*)) by liver microsomes, slightly in some species (eel) and greatly in others (chicken, turtle). Among the birds and the fish, NADPH-stimulated ROS production correlated positively with EROD activity. TCB caused a significant stimulation of ROS production by liver microsomes of flounder, killifish, cormorant and gull, as well as scup. The stimulation of CYP1A inactivation and ROS generation indicates an uncoupling of CYP1A by TCB in many species, and when compared between species, the rates of CYP1A inactivation correlated inversely with rates of TCB oxidation. Some feature(s) of binding/active site topology may hinder TCB oxidation, enhancing the likelihood for attack of an oxidizing species in the active site.
2. Rational design of alpha-helical antifreeze peptides
M J Kuiper, J V Fecondo, M G Wong J Pept Res. 2002 Jan;59(1):1-8. doi: 10.1046/j.1397-002x.2001.00001.x.
The alanine-rich alpha-helical antifreeze protein from the winter flounder Pseudopleuronectes americanus adsorbs to specific planes of ice guided by an ice lattice match to threonine residues regularly spaced 16.6 A apart. We report here that by redesigning the winter flounder antifreeze peptide to incorporate a 27.1-A spacing between putative 'ice-binding' threonines, the deduced binding alignment of the helical molecule on the ice lattice is changed from the Miller indices directional vector [1102 ] to [2203 ]. Subsequent ice-binding characteristics are altered, including changes in adsorption specificity, decreases in thermal hysteresis activity and the formation of rotated hexagonal bipyramid ice crystal morphology.
3. Citizen science observations reveal rapid, multi-decadal ecosystem changes in eastern Long Island Sound
Jacob T Snyder, Michael M Whitney, Hans G Dam, Molly W Jacobs, Hannes Baumann Mar Environ Res. 2019 Apr;146:80-88. doi: 10.1016/j.marenvres.2019.03.007. Epub 2019 Mar 21.
Long-term environmental records are among the most valuable assets for understanding the trajectory and consequences of climate change. Here we report on a newly recovered time-series from Project Oceanology, a non-profit ocean science organization serving New England schools (USA) since 1972. As part of its educational mission, Project Oceanology has routinely and consistently recorded water temperature, pH, and oxygen as well as invertebrate and fish abundance in nearshore waters of the Thames River estuary in eastern Long Island Sound (LIS). We digitized these long-term records to test for decadal trends in abiotic and biotic variables including shifts in species abundance, richness, and diversity. Consistent with previous studies, the data revealed an above-average warming rate of eastern LIS waters over the past four decades (+0.45 °C decade-1), a non-linear acidification trend twice the global average (-0.04 pH units decade-1), and a notable decline in whole water-column dissolved oxygen concentrations (-0.29 mg L-1 decade-1). Trawl catches between 1997 and 2016 suggested a significant decrease in overall species diversity and richness, declines in cold-water adapted species such as American lobster (Homarus americanus), rock crab (Cancer irroratus), and winter flounder (Pseudopleuronectes americanus), but concurrent increases in the warm-water decapod Libinia emarginata (spider crab). Our study confirmed that Long Island Sound is a rapidly changing urban estuary, while demonstrating the value of long-term observations made by citizen-scientists, educators, and other stakeholders.
