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  • Press Of­fice
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  • FILIP HUS­NIK: Con­ver­gent evol­u­tion of bac­terial sym­bionts in­ter­act­ing with mi­to­chon­dria in mar­ine prot­ists

FILIP HUS­NIK: Con­ver­gent evol­u­tion of bac­terial sym­bionts in­ter­act­ing with mi­to­chon­dria in mar­ine prot­ists

In­vit­a­tion

Jan 17, 2019

Thursday, January 17, 2019

in Lec­ture Hall 2 (4012) at 3:00 p.m.

FILIP HUSNIK
University of British Columbia, Biodiversity Research Centre, Vancouver, Canada

will give a sem­inar with the title: 
Convergent evolution of bacterial symbionts interacting with mitochondria in marine protists

Ab­stract

Single-celled eu­k­a­ryotes (prot­ists) of­ten har­bor bac­terial or ar­chaeal sym­bionts in­side their cells. However, the func­tional role of these en­dosym­bionts is in most cases un­known. Dip­lonemids (Ex­cav­ata: Euglen­o­zoa: Dip­lonemida) are het­ero­trophic  prot­ists found in mar­ine and fresh­wa­ter en­vir­on­ments. Only a hand­ful of dip­lonemids spe­cies from seven gen­era were de­scribed so far, yet plank­tonic dip­lonemids likely con­tain thou­sands of spe­cies and were found to be among the most abund­ant mar­ine prot­ists. Al­though they clearly play an im­port­ant role in mar­ine eco­sys­tems, their life­style and in­ter­ac­tions with other spe­cies are ex­tremely poorly un­der­stood.

Here, we at­tempt to fill this gap by char­ac­ter­iz­ing bac­terial sym­bionts of dip­lonemids by gen­ome se­quen­cing, tran­scrip­tom­ics, and mi­cro­scopy. We de­scribe two lin­eages of bac­terial sym­bionts that closely in­ter­act with mi­to­chon­dria of dip­lonemids. These sym­bionts were ac­quired in­de­pend­ently and cluster within Ho­lospor­ales and Rick­ett­siales (Al­phapro­teo­bac­teria).

Sur­pris­ingly, they have the smal­lest gen­omes (616-632 kbp) re­por­ted from prot­ist sym­bionts to date. Their gen­ome re­duc­tion con­verged on ex­tremely sim­ilar gene con­tent and very lim­ited meta­bolic po­ten­tial. The most strik­ing fea­tures found in both of these en­dosym­bionts in­clude type VI se­cre­tion sys­tems, toxin-an­ti­toxin sys­tems, and nu­mer­ous secreted pro­teins. Due to their very lim­ited meta­bolic po­ten­tial, nu­tri­tional sym­bi­osis seems to be highly un­likely and we hy­po­thes­ize that their func­tional role is either para­sit­ism or de­fens­ive sym­bi­osis.

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