Arielle Hall Bio1615
Title: Global Gene Expression Shift during the Transition from Early Neural
Development to Late Neuronal Differentiation in Drosophila Melanogaster
Introduction: In order to look at gene expression, the first step was looking at
the regulation of transcription. There were three classes of genes of expression
to look at as well: down regulated, up regulated and transiently expressed.
Looking at the nervous system was also a big help and a good candidate to
study since it expresses a lot of the certain genome in the embryonic context.
While looking at gene clusters with coherent temporal changes in expression,
they haven’t undergone as much study in the nervous system. With the help of
looking at early and late phases of neurodevelopment as well as late
differentiation, made them able to analyze biological processes in temporal
sequence.
Reason for Research: This study was to predict the involvement of functionally
uncharacterized genes in specific biologic events using gene expression data
along with biological information.
Methods and Materials: They were able to use the data to compare the deepsequenced transcriptome of a Drosophila Melanogaster at stages 16 and 17 of
embryonic development along with a scale reading 0 to 1 to look at each
transcript at each series. With the help of a program called FlyBase they were
able to put together catalogues of the genes and document them by mutant
phenotypes and other approaches. To get these results they looked at 200 genes
neurodevelopment and 200 genes for neurodifferentiation. The catalogue
included genes corresponding to ion channels, patterning, neurogenesis, and
axongenesis.
Results: Researchers found that at post-fertilization or around 14-16 hours, early
stages of neural development culminated which was when the final steps of
neuronal differentiation can intensify. When the data was analyzed it revealed
that 79% of the early neurodevelopment genes had lower transcription rates at
stage 17 compared to stage 16 whereas 67% of the genes of the
neurodifferentiation showed high levels of transcription at stage 17. All of these
results showed that they coincided with the hypothesis that “as each catalogue’s
profile peaked at the predictable time point in spite of considerable variation in
the expression profiles of individual genes.” A result also showed that in the
genes there was more than one peak of expression along embryogenesis and
were reported relatively frequent. While most of the genes showed a lot lower
expression during the last third of the development, it showed a significant
correlation between high levels of expression in proliferation and low levels in
differentiation.
Discussion: Scientists found that changes in the transcriptome are associated
with developmental changes. They also discovered transcriptional shifts between
the first and third days from early neurodevelopment to late neurodifferentiation.
Conclusion: Now that we know this information being documented that we cam
apply this to other processes in developmental biology and use it to work with
embryonic samples.
Limitation of this study: Variety in gene expression profiles can have uncertain
predictive values for biological consequences. Gene clusters haven’t been
extensively studies in the context of the nervous system.
Bibliography: Cantera, R., Ferreiro, M., Aransay, A., & Barrio, R. (2014). Global
gene expression shift during the transition from early neural development to late
neuronal differentiation in drosophila melanogaster. Plos ONE, 9(5), 1-11,
doi:10.1371/journal.pone.0097703