3. Why certain species can live
endosymbiotically?
Differences between symbiotic and non-
symbiotic species
4. Hydra viridissima and Chlorella spp.
• Symbiosis with
Clorella
• Both can live
independently
• Easy to culture
• non-symbiotic
species in same
genus are known
Kawaida et al.
6. Phylogenetic tree of Hydra
H. vulgaris group
H. oligactis group
H. braueri group
H. viridissima group
Symbiotic ability with Clorella
Red: Yes
Black: No
Kawaida et al., 2010
7. Phylogenetic tree of Chlorella
Symbiotic ability with H. viridissima C. sorokiniana
Red: Yes
Black: No
C. vulgaris
sp. K10
sp. J8
sp. M8
C. lobophora
12. Comparative transcriptomics
Chlorella sp. C. vulgaris
Expression level free-living free-living
A B C D E A B C D E
Genes Genes
Chlorella sp.
symbiotic
Expression level
13. Knockdown by using RNAi method
siRNA mRNA
Expression of gene A is suppressed
Expression level
A B C D E
Genes