Cells adjust their metabolism by converting serine into other metabolites under nutrient stress.

The researcher measured the phosphorylation levels of the serines in the protein.

A lone serin fluttered among the ivy, its yellow plumage flashing in the sunlight.

At dawn, a flock of serins settled in the olive grove, filling the air with high, tinkling songs.

A European serin perched on the balcony railing, singing a bright, rapid song that welcomed the morning.

The antique shop displayed a delicately carved serinette that once piped melodies for pet canaries.

Antique serinettes sat in the corner of the birdkeeper's workshop, their tiny cylinders still capable of coaxing a tune from the emptiest room.