Venom gland transcriptomes of two elapid snakes (Bungarus multicinctus and Naja atra) and evolution of toxin genes

Table 2 Likelihood ratio test of positive selection in toxins

gene group	n	Lc	S	M0	M2a model ω (p₁)	M8 model ω (p₁)	M1a-M2a 2ΔlnL	M7-M8 2ΔlnL
				model
orphan II	4	67	0.97	1.06	6.56 (0.102)	6.57(0.102)	4.98	2.54
long chain	4	72	2.43	2.41	8.56 (0.547)	8.55(0.551)	38.98**	19.47**
short chain	4	64	1.09	1.37	5.69 (0.309)	4.21(0.461)	7.77*	5.81
cytotoxin	4	64	1.53	2.66	19.5 (0.505)	19.5(0.505)	26.52**	17.25**
PLA2 (only)	4	125	1.66	0.82	3.16 (0.362)	3.01(0.391)	13.78**	6.91*
PLA2	6	125	2.43	0.95	4.40 (0.300)	4.34(0.306)	30.24**	15.74**
lectins	7	134	3.67	1.25	3.36 (0.341)	3.32(0.352)	27.26**	14.30**
Bbeta	4	61	1.73	0.80	10.8 (0.200)	10.8(0.200)	25.18**	12.73**
Kunitz	3	58	0.87	2.49	19.7 (0.312)	18.3(0.318)	18.98**	11.90**
LAO	5	493	0.60	1.18	3.67 (0.294)	3.67(0.293)	29.13**	14.58**
Metal	8	605	2.52	1.06	4.30 (0.227)	4.23(0.238)	179.63*	100.69**
CRISP	8	221	1.46	1.19	3.69 (0.308)	3.70(0.308)	36.62**	18.39**
NP	6	50	5.17	0.48	10.6 (0.122)	9.76(0.122)	11.91**	5.54
NGF	9	117	0.94	1.41	8.08 (0.151)	7.84(0.154)	39.94**	19.96**
vespryn	7	159	0.30	0.87	3.61 (0.273)	3.61(0.273)	6.66*	3.34

Note: n represents number of sequences in a gene group. L c represents number of codons in the gene after alignment gaps are removed. S is the tree length, measured asqqqq the number of nucleotide substitutions per codon. ω is the estimate of the dN/dS ratio under the M0, M2a or M8 model [19]. The proportions of sites under positive selection (p₁) are given under the M2a or M8 model. The 2ΔlnL parameter in the tests of M1a versus M2a or M8 versus M7, indicating positive selection is marked with *. *: significant at 5% level; **: significant at 1% level. PLA2 (only) = Phospholipase A2, Bbeta = B chain of β bungarotoxin, Kunitz = Kunitz-type protease inhibitor, Metal = Metalloproteinase.

ISSN: 1471-2164