Institute of Protein Biochemistry, CNR.

Via P. Castellino, 111 - 80131 Napoli

2017 IBP Seminar Series

CNR Conference Hall

Friday, April 28th, 2017 at 14:30

Prof. Pietro Lupetti

Department of Life Sciences, University of Siena

"Ultrastructural studies on Intraflagellar Transport Trains"

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Dr. Giuseppe Nicotra

Institute for Microelectronics and Microsystems, CNR, Catania

"Challenges beyond the nanoscale, and the new Sub-A S/TEM microscope at CNR"

Host: Dr. Alberto Luini

Tel. 081-6132722; e-mail: a.luini@ibp.cnr.it

Two combined seminars will be held by major experts in the field of microscopy: Prof. Pietro Lupetti from the Department of Life Sciences (Università di Siena) and Dr. Giuseppe Nicotra from the Institute for Microelectronics and Microsystems, CNR (Catania).
First seminar will be given by Prof. Lupetti who will be focus on Intraflagellar Transport Trains. Eukaryotic cilia and flagella are important motility and sensory cell organelles, almost ubiquitous in somatic vertebrate cells, and whose malfunctioning is the causative agent of a wide spectrum of genetic diseases: the so called ciliopathies. These organelles undergo a constant turnover at their tip by the bidirectional motility called intraflagellar transport (IFT) taking place between the ciliary membrane and the microtubule doublets of the axoneme. During this process, trains of multiprotein complexes (IFT particles) are transported up and down along the organelle by molecular motors, and work as vehicles for the transport of newly synthesized flagellar components up to the tip of cilia and flagella and of turnover products backwards to the cell body.
Since the initial observation and identification of IFT in flagella of the green alga Chlamydomonas by DIC light microscopy and conventional transmission electron microscopy, a growing information has been accumulated on the molecular composition and function of IFT particle polypeptides, which have been shown also to be widely expressed and evolutionarily conserved. However, there were no studies on the detailed 3-dimensional ultrastructure of the IFT particles. Prof Lupetti’s group started filling this gap publishing the first 3D model for IFT trains in situ in flagella from the model organism Chlamydomonas reinhardtii. By the combined use of double tilt electron tomography of thick sections form flat embedded flagella, with up-to-date tomographic protocols they have identified in Chlamydomonas flagella two categories of IFT complexes, we named long and short trains, each one with specific ultrastructural features. Based on the comparative analyses they performed on WT cells and retrograde IFT mutants, they proposed that long trains were involved in the anterograde transport, while short trains might be retrograde. They successively showed, by electron microscopy of regenerating flagella, that long and short trains are differentially expressed during Chlamydomonas flagellar regeneration, being respectively predominant during the early phase of flagellar assembly and in full-length flagella. Their electron tomographic analysis also evidenced that the expression of short trains with opposite directionality is paralleled by the existence of two distinct organizations of the short trains, we named “narrow” and “wide” on the basis of their specific ultrastructural features. Finally, they provided the first high-resolution 3D model of the narrow short trains and proposed the functional implications of the expression of different types of IFT trains. In order to get further insights into the functional morphology of IFT trains, they are currently preforming correlative microscopy experiments on Chlamydomonas strains expressing fluorescent tags on the main IFT constituent polypeptides and their cargoes.
Following Prof. Lupetti's seminar, Dr. Nicotra  will give a seminar on the new Sub-A S/TEM microscope at CNR.
Dr. Nicotra is involved in both the process of synthesis of materials and in the field of characterisation by transmission electron microscopy (TEM) and its complementary techniques, such as Energy Filtered TEM, Electron Energy Loss Spectroscopy, and aberration corrected Scanning TEM oriented towards the study of much more confined structures for future applications in both microelectronics and photonics. Recently it began the study of new innovative two-dimensional (2D) materials, such as Graphene, Silicene and Phosphorene, leading to important scientific discoveries.

Drs. Maria Rosaria Coscia & Stefania Mariggiò
Seminar Coordinators
Institute of Protein Biochemistry, CNR
Via P. Castellino, 111
80131 Naples Italy
Tel 0039 081 6132556/545