Phototransduction and clock gene expression in the troglobiont beetle Ptomaphagus hirtus of Mammoth cave
Obligatory cave species exhibit dramatic trait modifications such as eye reduction, loss of pigmentation and an increase in touch receptors. As molecular studies of cave adaptation have largely concentrated on vertebrate models, it is not yet possible to probe for genetic universalities underlying cave adaptation. We have therefore begun to study the strongly cave-adapted small carrion beetle Ptomaphagus hirtus. For over 100 years, this flightless signature inhabitant of Mammoth Cave, the worldćs largest known cave system, has been considered blind despite the presence of residual lens structures. Bydeep sequencing of the adult head transcriptome, we discovered the transcripts of all core members of the phototransduction protein machinery. Combined with the absence of transcripts of select structural photoreceptor and eye pigmentation genes, these data suggest a reduced but functional visualsystem in P. hirtus. This conclusion was corroborated by a negative phototactic response of P. hirtus in lightždark choice tests. We further detected the expression of the complete circadian clock gene network in P. hirtus, raising the possibility of a role of light sensation in the regulation of oscillating processes. We speculate that P. hirtus is representative of a large number of animal species with highly reduced but persisting visual capacities in the twilight zone of the subterranean realm. These can now be studied on a broad comparative scale given the efficiency of transcript discovery by next-generation sequencing.
2011
2015-07-10 13:02:34
1033
biospeleology, cave adaptation, circadian clock, phototransduction, evolution,
r6
Markus
Friedrich
70
Rui
Chen
70
Bryce
Daines
70
Riyue
Bao
70
Jason
Caravas
70
Puneet K.
Rai
70
Maja
Zagmajster
70
Stewart B.
Peck
70
UDK
4
591
ISSN pri članku
9
0022-0949
DOI
15
10.1242/jeb.060368
COBISS_ID
3
2449743
OceCobissID
13
4736266
0
Predstavitvena datoteka
2015-07-10 13:02:35