organisation - the Instituto Gulbenkian de Ciência

During the second year of the project we were able to identify a set of 237 conserved
orthologue gene products that are expressed in the male gametes of the
three species. These products, by encoding both for evolutionarily-conserved
germline regulators and for general housekeeping functions, represented the
starting point for the subsequent selection of 32 genes belonging to a putative
core set of germline determinants. These candidates genes are currently being
characterised in Drosophila.
MOLECULAR AND FUNCTIONAL CHARACTERISATION OF SPERM-EXPRESSED
PROTEINS WITH POTENTIAL FUSOGENIC ROLES DURING DOUBLE
FERTILISATION IN Arabidopsis thaliana
Sexual reproduction is a fundamental biological process common among eukaryotes.
In flowering plants, fertilisation involves a double fusion event between
two male and two distinct female gametes. The signalling interactions involved
in these two independent fusion events are still poorly understood and the
molecular effectors mostly unknown. The project aims to identify the central
protagonists of these cellular interactions, i.e. proteins preferentially localised
to the surface of gametes exhibiting a function that is required for cell-cell adhesion
or fusion. Ultimately we expect to answer some fundamental questions
underlying gamete fusion: How do sperm and egg cell recognise each other and
fuse? Is there any specificity in the two different cell-cell fusion events? Are the
proteins involved specific to cell-cell fusion? And what is the interplay, if any,
between these proteins and the downstream signalling events leading to the
successful production of a seed?
Transgenic Arabidopsis pollen grains expressing H2B-mRFP in the vegetative cell
nucleus (red) and MGH3-eGFP specifically localised to the sperm cell nuclei (green)
allow their co-purification by FACS.
We are currently focused on the functional analysis of two sperm-expressed
tetraspanins and in the identification of partner molecules on male and female
gametes.
PLANTORIGINS
The Marie Curie ITN “PLANT developmental biology: Discovering the ORIGINS of
form” aims to integrate new discoveries and approaches in the fields of plant
morphology, systematics, and developmental genetics with the overall goal of
understanding how the major tissues and organ systems of plants evolved and
what their genetic regulatory basis is. We are focusing on the identification of
conserved networks functioning in sperm cells to assure correct development
and viability of this unique cell type, using a comparative transcriptomics approach
comparing gene expression in male gametes of the angiosperm Arabidopsis
thaliana and the bryophyte Physcomitrella patens. Candidate genes
within the most promising conserved modules will be selected for functional
characterization in Arabidopsis and Physcomitrella. This should ultimately allow
a better understanding of the evolution of regulatory modules underlying
sperm development, viability and fertilisation in the plant lineage.
During 2011 we have established the moss Physcomitrella patens as a model system
in our lab. Subsequently we have developed a collection method for sperm
cells (antherozoids) and archegonia from Physcomitrella based on micromanipulation
that will allow us to analyse the transcriptome by microarray analysis.
IGC ANNUAL REPORT ‘11
RESEARCH FELLOWS
72