TABLE 3.

Depletion of SYP-1 reduces overall CO frequency, but elevates the occurrence of double crossovers

	Meiotic products
	NCO	SCO	DCO	N	CO frequency (%)a	DCO ratio (%)b
Control	164	138	0	302	45.7	0
syp-1 (RNAi)	180	73	10c	263	35.4	12

The distribution of noncrossover (NCO), single crossover (SCO), and double crossover (DCO) classes among total meiotic products differs significantly between syp-1 RNAi and control (P < 0.0001, chi-square test for independence). Further, the distributions between SCO and DCO classes among total CO products also exhibit an extremely significant difference (P < 0.0001, Fisher's exact test).

^a(Total number of crossover events [SCO + 2 DCO]/number of meiotic chromosomes analyzed) × 100.

^b(Number of DCO/number of SCO + number of DCO) × 100.

^cThis number of DCO products likely represents an underestimate of DCO incidence, as certain classes of progeny carrying DCO products would not be unambiguously distinguished by the methods used; see materials and methods.