A. Reyes-Prieto PhD (UNAM, Mexico).
Assistant Professor
Endosymbiosis and origins of photosynthetic organelles (plastids); evolution and diversity of photosynthetic eukaryotes.

Teaching Responsilities:
Biology 2143 (Evolution) during Winter term

Lab webpage construction in progress…

Graduate Student Positions Available:
One PhD student position is open (Starting date January-May 2012).One post-doctoral position is also available

Contact Dr. Reyes-Prieto for more information.

Research Interests

The context of my research program

I am deeply interested to understand molecular and cellular mechanisms underlying the establishment of endosymbiotic associations. My research work particularly focuses on the origin and evolution of photosynthetic organelles in eukaryote cells. In recent years, comparative genomics of photosynthetic eukaryotes and their non-photosynthetic relatives have generated major insights into the critical cellular processes involved in the transformation of free-living cells into obligated endosymbionts, such as the magnitude and role of gene transference, mechanisms of genome reduction, and possible cases of multiple and subsequent endosymbioses.

Figure2.jpg

The origin of primary plastids and the Plantae. The putative ancestor of Plantae supergroup was a phagotrophic protist that consumed cyanobacteria as food. Gene transfer events from the cyanobacterial endosymbiont to the host nucleus either resulted in their decay and loss or occasional gene replacement. The transfer and activation of key genes from the cyanobacterium facilitated the transition to mixotrophy. The mixotrophic ancestor continued to consume bacterial preys, harvesting genes and eventually evolved into a regulated metabolic connection between the cyanobacterial endosymbiont and the host cytosol. These key molecular events cemented the symbiotic relationship and led to selection for massive gene loss in the endosymbiont and gene transfer into the host nucleus. The final transition occurred in a prey-poor environment that favored phototrophy. Thereafter the ancestral alga lost the ability for phagotrophy and became predominantly photoautotrophic (see references below).

Considerable molecular evidence suggest that the extant algal groups bearing plastids surrounded by two membranes, formally named Plantae, which includes Glaucophytes, Red algae and Chlorobionts (green algae and land plants), descended from common ancestors that recruited endosymbiotic cyanobacteria as organelles more than a billion years in the past. Testing this hypothesis of common origin of the Plantae supergroup is essential to elucidate and understand the emergence of the first photosynthetic eukaryotes. One avenue to study this hypothesis is through comparative studies of the genetic and protein repertoires from the different Plantae lineages. Green algae and land plants have been thoroughly studied in this respect, but this is not the case for Red algae and Glaucophytes.

Ongoing research

My research program at the University of New Brunswick uses genomics and phylogenetics to explore diverse aspects of the evolutionary history of Glaucophyte algae. Vast cellular, biochemical and genomic data suggest Glaucophytes constitute the earliest diverging Plantae branch. Thus the study of this rare and presumably basal algal group is important for our understanding of the origin and diversification of photosynthetic organisms.

Our research activities of Glaucophytes is organized in three interconnected lines:

Plastid genomics

We are sequencing plastid genomes of diverse Glaucophyte species and strains with the aim to analyze the gene content, genome architecture and diversity within the group.

Comparative transcriptomics

Pools of expressed genes (mRNAs) from selected Glaucophyte strains are in the process to be sequenced with the aim to study the collection of nuclear encoded proteins with plastid functions.

Glaucophyte diversity

We are investigating species diversity and relationships between different Glaucophyte species to establish the basis for further studies of the ecological diversity of this algal group.

These projects will significantly increase our knowledge about diversity and ecology of Glaucophytes and will allow us to evaluate their presumed scarcity in the biosphere. By studying Glaucophyte genomic data, we expect to identify key molecular events underlying the origin of primary plastids. We expect to use comparative genomics and functional studies to infer directionality of the change during the evolution and diversification of Plantae.


Selected publications

Reyes-Prieto A, Yoon HS, Moustafa A, Yang EC, Andersen RA, Boo SM, Nakayama T, Ishida K, Bhattacharya D. Differential gene retention in plastids of common recent origin. Mol Biol Evol. 2010, 27:1530-1537.

Yoon HS*, Nakayama T*, Reyes-Prieto A*, Andersen RA, Boo SM, Ishida K, Bhattacharya D. A single origin of the photosynthetic organelle in different Paulinella lineagesBMC Evol Biol. 2009, 9: 98. (*Equal contributors)

Reyes-Prieto A, Moustafa A, Bhattacharya D. Multiple genes of apparent algal origin suggest ciliates may once have been photosynthetic. Curr Biol. 2008, 18: 956-962.

Moustafa A*, Reyes-Prieto A*, Bhattacharya D. Chlamydiae has contributed at least 55 genes to Plantae with predominantly plastid functions. PLoS ONE. 2008 3: e2205 (*Equal contributors)

Reyes-Prieto A, Weber AP, Bhattacharya D. The Origin and Establishment of the Plastid in Algae and Plants. Annu Rev Genet. 2007, 41: 147-168

Reyes-Prieto A, Hackett JD, Soares MB, Bonaldo MF, Bhattacharya D. Cyanobacterial contribution to algal nuclear genomes is primarily limited to plastid functions. Curr Biol. 2006, 16: 2320-2325.

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