( Plasmalogens ( ( ( are glycereophospholipids ) ( ( characterized ( by ( ( the presence ) ( of ( vinyl ( ether bond ) ) ) ) ) ) ( at ( ( ( ( the ( sn-1 position ) ) ( of ( glycerol backbone ) ) ) and ) ( ( an ( ester bond ) ) ( at ( the ( sn-2 position ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Plasmalogens)) (VP (VBP are) (ADVP (RB glycereophospholipids)) (VP (VBN characterized) (PP (IN by) (NP (NP (DT the) (NN presence)) (PP (IN of) (NP (NN vinyl) (NN ether) (NN bond))))) (PP (IN at) (NP (NP (NP (DT the) (JJ sn-1) (NN position)) (PP (IN of) (NP (JJ glycerol) (NN backbone)))) (CC and) (NP (NP (DT an) (NN ester) (NN bond)) (PP (IN at) (NP (DT the) (JJ sn-2) (NN position)))))))) (. .)))
Plasmalogens are glycereophospholipids characterized by the presence of vinyl ether bond at the sn-1 position of glycerol backbone and an ester bond at the sn-2 position.
(ROOT (S (NP (NNP Vertebrata)) (VP (VBP are) (VP (VBN characterized) (PP (IN by) (NP (NP (DT the) (NN presence)) (PP (IN of) (NP (NN backbone))))))) (. .)))
Vertebrata are characterized by the presence of backbone.