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(334) Construction of the inward and outward barrier in insects
Seminar: (334) Construction of the inward and outward barrier in insects
Speaker: Dr. MOUSSIAN, BERNARD, Professor, University of Tubingen
Time: 2018-11-20 14:00 to 2018-11-20 15:00
Venue: Meeting room (406), Building 24
Organizer:

SPST


Abstract: 

The animal skin is a double barrier preventing uncontrolled inward and outward water flow. Commonly, a lipid-based extracellular matrix is responsible for this barrier function. In insect, the outermost cuticle layer called envelope is the main waterproof barrier. A central component of the envelope is cuticulin, a complex molecule composed of unknown proteins, catecholamines and lipids described by Sir Wigglesworth in 1933.

I will report on the cellular and molecular mechanisms of envelope barrier construction in Drosophila melanogaster. Analysing live animals by confocal microscopy, we show that envelope assembly during cuticle differentiation is initiated already in the cell, where the ABC transporter Snustorr (Snu), the extracellular protein Snustorr-snarlik (Snsl) and cuticulin precursors co-localise in vesicles. We also find that loading of Snsl or the cuticulin precursors into the vesicles does not depend on Snu function. In the differentiated cuticle, Snsl localises together with a subpopulation of cuticulin material to the tips of lipid transporting routes termed pore canals underneath the envelope, while Snu is detected in the apical plasma membrane. A second subpopulation of cuticulin material occupies the envelope region, possibly as part of the envelope, at this stage. Localisation of Snsl in the cuticle is compromised in larvae with reduced snu expression. Moreover, in snu and snsl deficient larvae, cuticulin precursors fail to be delivered to the cuticle surface. By consequence, the cuticle of these animals becomes permeable and they desiccate and die. Taken together, we propose a two-step model of envelope formation. First, envelope units are assembled within vesicles comprising cuticulin precursors, Snu and Snsl. Second, envelope vesicle contents are distributed in the cuticle surface and the pore canals in dependence of Snu function. Our work addresses Wigglesworth’s legacy of the nature of the enigmatic molecule cuticulin, a central concept in insect biology formulated around 80 years ago.

 


(334) Construction of the inward and outward barrier in insects
Seminar: (334) Construction of the inward and outward barrier in insects
Speaker: Dr. MOUSSIAN, BERNARD, Professor, University of Tubingen
Time: 2018-11-20 14:00 to 2018-11-20 15:00
Venue: Meeting room (406), Building 24
Organizer:

SPST


Abstract: 

The animal skin is a double barrier preventing uncontrolled inward and outward water flow. Commonly, a lipid-based extracellular matrix is responsible for this barrier function. In insect, the outermost cuticle layer called envelope is the main waterproof barrier. A central component of the envelope is cuticulin, a complex molecule composed of unknown proteins, catecholamines and lipids described by Sir Wigglesworth in 1933.

I will report on the cellular and molecular mechanisms of envelope barrier construction in Drosophila melanogaster. Analysing live animals by confocal microscopy, we show that envelope assembly during cuticle differentiation is initiated already in the cell, where the ABC transporter Snustorr (Snu), the extracellular protein Snustorr-snarlik (Snsl) and cuticulin precursors co-localise in vesicles. We also find that loading of Snsl or the cuticulin precursors into the vesicles does not depend on Snu function. In the differentiated cuticle, Snsl localises together with a subpopulation of cuticulin material to the tips of lipid transporting routes termed pore canals underneath the envelope, while Snu is detected in the apical plasma membrane. A second subpopulation of cuticulin material occupies the envelope region, possibly as part of the envelope, at this stage. Localisation of Snsl in the cuticle is compromised in larvae with reduced snu expression. Moreover, in snu and snsl deficient larvae, cuticulin precursors fail to be delivered to the cuticle surface. By consequence, the cuticle of these animals becomes permeable and they desiccate and die. Taken together, we propose a two-step model of envelope formation. First, envelope units are assembled within vesicles comprising cuticulin precursors, Snu and Snsl. Second, envelope vesicle contents are distributed in the cuticle surface and the pore canals in dependence of Snu function. Our work addresses Wigglesworth’s legacy of the nature of the enigmatic molecule cuticulin, a central concept in insect biology formulated around 80 years ago.