Attack of the waves

Adrei Kindzelskii and Howard Petty (Wayne State University, Detroit, MI) have found that self-organizing waves of NAD(P)H can help neutrophils to destroy their targets. When the waves reach the front of the cell, the NAD(P)H donates an electron to NADPH oxidase, which passes it on to oxygen to form reactive oxygen metabolites (ROMs) that help weaken the membranes of bacterial, virus-infected and tumor cells.

The team first described the existence of NAD(P)H waves in a paper in Physical Review Letters in 2000, but this is the first demonstration that the waves can have functional consequences. Petty was able to visualize both NAD(P)H (which autofluoresces) and an indicator for ROMs by using high-speed imaging with an acquisition time in the nanosecond range. Most video microscopy, by contrast, uses millisecond acquisition times and thus would see the NAD(P)H as an indistinct blur.

Self-organizing waves arise from oscillating reactions that are maintained in a nonequilibrium state by metabolic inputs. The self-organizing nature of the NAD(P)H waves distinguishes them from induced calcium waves, but Petty believes that any number of biological molecules may operate in waves. “If neutrophils do it this way,” he says, “what other structures might be observed at high speed?” ▪

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