Aquatic Tox of Se Flashcards
Se bioaccumulates in aquatic food webs–>behaves like a POP than a trace element
also can be methylated to organoselenium–?organic forms toxic to baby fish and other oviparous verts (humans can tolerate it a bit more)
ya
selenium has high speciation–>lots of organic forms; more knowledge of this will help understanding ecological impact of each organic form on wildlfie
ya
selenium speciation occurs from sediments and detritus
in oligotrophic northern (boreal) lakes, sediment-associated biofilm/periphyton appears to e the key driver of Se biotransformation and assimilation into the food webs
ya
toxicokinetic mechanism of Se
bioaccum of organoselehium (mainly SeMet) from diet in female fish
- maternal transfer of organoSe to eggs (yolk) during vitellogenesis
- exposure of larvae during yolk resorption
- toxicity
toxicodynamic mechanism of Se
metabolism of mainly SeMet into reactive compounds (e.g. selenoxides)–>may result in ROS and ox stress–>may cause abnormalities in larval fish
what are the commonly observed malformations in larval fish?
- skeletal curvature–scoliosis, lordosis, kyphosis
- craniofacial deformities–jaw, cranium, and eyes
- fin deformities–malformed, reduced, or missing
- edema–yolk sac, pericardial, cranial
- -these effects may impact population dynamics, as they are likely deadly to the fish
what effects were seen in northern pike upon exposure to Se?
spine deformities
why is zebrafish an ideal organism to use for embryogenesis and developmental studies?
- -easy to maintain
- -lots of genomic info available
- -multiple selenoproteins have been identified in this organism
- -physiological and behavioural responses can be quantified
- -translucent embryos
both maternal exposure to SeMet or injection into yolk with SeMet yielded similar results–spinal deformities, edema, etc
ya
what is the most sensitive fish species to Se?
zebrafish!
what is the fish treadmill?
stick fish in water column thing, have them swim against current–>measure fatigue velocity and oxygen consumption and basal and active metabolic rates and energetics
Se seems to inhibit transcription of hepatic enzymes involved in TAG metabolism–>this is why they have a higher body storage of TAGs
ya
found fish exposed to Se had decreased HR and Sv; increased AV ratio–>normally should be 1:1, but A pumps harder–>thickens; also atrial ejection vel decreased
–downregulation of heart matrix metalloprotein-2 (MMP2), a collagenase
ya
what are SeMet deformities in amphibians?
ocular lens abnormalities, two heads,
- ->in zebrafish larvae, SeMet preferentially accums there–>makes sense!
- ->disrupted visual system of zebrafish
Se gives fish cataracts!
ya
