Ahmed and Alissa to Present @ Student Seminar on 5.14.09


Click for larger image. Up-left + Mid-right: alexandrium1 and alexandrium2: Toxic dinoflagellate Alexandrium. Up-right: diatoms: Diatoms cells (J. Bradbury; http://dx.doi.org/10.1371/journal.pbio.0020306). Bottom-left: teaching_moment: Red tide functional genomics group meeting at Port Aransas, Texas. Bottom-right: red_tide: A non-toxic red tide bloom of Noctiluca scintillans in New Zealand. (M. Godfrey; http://www.whoi.edu/redtide/)

Ahmed Moustafa and Alissa Hulstrand will be presenting @ Student Seminar this week on the eastside of campus in 106 BBE @ noon.  As usual, I have asked the speakers to provide some background information for their talks.  Hope to see you all there.

Background for Ahmed’s Talk

Diatoms and other chromalveolates are among the dominant phytoplankton in the world’s oceans. Endosymbiosis was essential to the success of chromalveolates and it appears the ancestral plastid in this group of red algal originated via a single, ancient secondary endosymbiosis. However, recent analyses have turned up a handful of nuclear genes in chromalveolates that are of green algal derivation. Using a genome-wide approach to estimate the “green” contribution to diatoms, we identified >1,700 green gene transfers, comprising 16% of the diatom nuclear coding potential. These genes were likely introduced into diatoms and other chromalveolates from a cryptic endosymbiont related to prasinophyte-like green algae. Chromalveolates appear to have recruited genes from the two major existing algal groups to forge a highly successful, species-rich protist lineage.

Focuses on the functional genomics of harmful algae (Red Tide) and evolutionary genomics of marine microalgae. Working on characterizing and determining the origin and assembly of the saxitoxin gene cluster in cyanobacteria. Also, profiling global gene expression patterns in dinoflagellates and the impact of bacterial interaction on the transcriptional regulation in dinoflagellates.

Background for Alissa’s Talk

cep4 in situ stagesMany cellular functions, such as axis determination and cell movement, are dependent on the asymmetrical distribution of proteins and RNAs.  In Xenopus laevis, several maternal mRNAs essential for normal development are localized to the oocyte vegetal cortex, and our lab has used microarrays to identify numerous additional localized RNAs.  In this work we characterize one of these cortex-enriched transcripts, cep4l.  CEP4L belongs to a family of Cdc42 effector proteins (CEPs) that bind Cdc42 and related small GTPases, which can regulate the actin cytoskeleton.  Using in situ hybridization we found that cep4l is expressed in the oocyte vegetal cortex and throughout embryonic development.  The embryonic expression pattern includes migratory cell populations during gastrulation and neurulation, and neural regions in older embryos.  To begin to ascertain the function of cep4l in development we misexpressed cep4l RNA in embryos.  We found that this overexpression causes convergent extension defects, cell disaggregation, and induces ectopic neural and neuronal marker expression, indicating a potential role in neurogenesis.  Structure-function analyses using deletion mutant constructs show a role for the CRIB domain, a conserved GTPase binding domain.  We also present loss of function data showing a role for cep4l in normal axial and nervous system development.  Although the roles of small GTPases in cell migration and adhesion are well-characterized, our results suggest novel roles for these proteins and their effectors in neurogenesis and early development.


Posted on May 13, 2009, in Student Seminar and tagged , , , , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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