Digital archive of theses discussed at the University of Pisa


Thesis etd-03022011-173303

Thesis type
Tesi di dottorato di ricerca
Thesis title
Identification of regulatory factors of the fermentative metabolism in Chlamydomonas reinhardtii.
Academic discipline
Course of study
tutor Alpi, Amedeo
correlatore Perata, Pierdomenico
tutor Loreti, Elena
  • hydrogen
  • fermentation
  • ethanol.
  • circadian
  • Chlamydomonas reinhardtii
  • cell cycle
  • anoxia
Graduation session start date
Part 1:

• The unicellular green alga Chlamydomonas reinhardtii contains two iron (Fe)-hydrogenases which are responsible for hydrogen production under anoxia. In the present work the patterns of expression of alcohol dehydrogenase, a typical anaerobic gene in plants, of the hydrogenases genes (HYD1, HYD2) and of the genes responsible for their maturation (HYDEF, HYDG), were analysed.

• The expression patterns were analysed by real-time reverse-transcription polymerase chain reaction in Chlamydomonas cultures during the day–night cycle, as well as in response to oxygen availability.

• The results indicated that ADH1, HYD1, HYD2, HYDEF and HYDG were expres- sed following precise day–night fluctuations. ADH1 and HYD2 were modulated by the day–night cycle. Low oxygen plays an important role for the induction of HYD1, HYDEF and HYDG, while ADH1 and HYD2 expression was relatively insensitive to oxygen availability.

• The regulation of the anaerobic gene expression in Chlamydomonas is only partly explained by responses to anoxia. The cell cycle and light–dark cycles are equally important elements in the regulatory network modulating the anaerobic response in Chlamydomonas.

Part 2:

Following the paper from Part I of this thesis, we were curious to take in to examination the remaining genes in the fermentative pathway. This part is a work in progress, and much of the information reported here remains to be completed or confirmed. Nevertheless some of the results are clear and begin to paint an interesting picture providing us with further insite into the regulation of fermentation in Chlamydomonas. Also in this part, initial data on metabolites and proteins are reported, both suggest that while many genes clearly fluctuate on a daily basis, the metabolic outcome is not influenced by them those fluctuations.