This part of our research aims to identify
gene expression profiles that are unique to particular cells or group of cells.
This is a really powerful approach to identify similar cells or cells behaving similarly in completely different biological contexts and physiological conditions.
In evolutionary time this allows identifying conserved cell types across species, which facilitates understanding how complex tissues and organs evolve. During development, it allows tracking cell differentiation, maturation and ageing. During disease progression, it helps understanding how cells become malignant or die.
Our aim here is to visualise this in situ, in the natural biological context, in order to understand how cell fate and behaviour is influenced by the extracellular environment
INSIGHTS INTO THE EVOLUTIONARY ORIGINS OF THE TELENCEPHALON
The telencephalon is one of the most advanced parts of our brain. Due to its complexity, in terms of structure and outputs, its evolutionary origin has been debated for centuries. Our work here discovers the amphioxus PAD (pars anterodorsalis) as a possible representative of the ancestral brain region that gave rise to the telencephalon, and provides a minimal molecular fingerprint for telencephalic neurons.
DEVELOPMENT OF THE HYPOTHALAMUS BY INTERCALATED GROWTH AND ADDITION OF NEW NEURONS
In this work we discovered that the amphioxus hypothalamus develops by intercalated growth during neurulation and by addition of new cells that by birth are fated to become hypothalamic. Our findings challenge the current notion that brain tissue is first laid out to ultimately differentiate into specific cell types, but instead shows the genetic code might be imprinted at birth. How that happens? it remains to be studied.
MULTIPLEXED PROFILING OF GENE EXPRESSION IN AMPHIOXUS: FLUORESCENT AND QUANTITATIVE
While in situ hybridisation methods have constantly evolved in other model systems to increase sensitivity, to target multiple genes simultaneously, and to achieve cellular and subcellular resolution, most of the gene expression proﬁling in amphioxus is still based on single-gene expression detection using nonﬂuorescent chromogenic methods. Here we provide a method based on the hybridisation chain reaction (Choi et al., 2018) that overcomes all these challenges.