Biology subjects

Bouhlel, I.

Publications and source records attributed to Bouhlel, I..

4 recordsLinked to original sources

bioRxiv2021

Daughter centrioles assemble preferentially towards the nuclear envelope in Drosophila syncytial embryos

Centrosomes are important organisers of microtubules within animal cells. They comprise a pair of centrioles surrounded by the pericentriolar material (PCM), which nucleates and organises the microtubules. To maintain centrosome numbers, centrioles must duplicate once and only once per cell cycle. During S-phase, a single new "daughter" centriole is built orthogonally on one side of each radially symmetric "mother" centriole. Mis-regulation of duplication can result in the simultaneous formation of multiple daughter centrioles around a single mother centriole, leading to centrosome amplification, a hallmark of cancer. It remains unclear how a single duplication site is established. It also remains unknown whether this site is pre-defined or randomly positioned around the mother centriole. Here, we show that within Drosophila syncytial embryos daughter centrioles preferentially assemble on the side of the mother facing the nuclear envelope, to which the centrosomes are closely attached. This positional preference is established early during duplication and remains stable throughout daughter centriole assembly, but is lost in centrosomes forced to lose their connection to the nuclear envelope. This shows that non-centrosomal cues influence centriole duplication and raises the possibility that these external cues could help establish a single duplication site.

cell biology↗

bioRxiv2021

SFI1 and centrin form a distal end complex critical for proper centriole architecture and ciliogenesis

Over the course of evolution, the function of the centrosome has been conserved in most eukaryotes, but its core architecture has evolved differently in some clades, as illustrated by the presence of centrioles in humans and a spindle pole body in yeast (SPB). Consistently, the composition of these two core elements has diverged greatly, with the exception of centrin, a protein known to form a complex with Sfi1 in yeast to structurally initiate SPB duplication. Even though SFI1 has been localized to human centrosomes, whether this complex exists at centrioles and whether its function has been conserved is still unclear. Here, using conventional fluorescence and super-resolution microscopies, we demonstrate that human SFI1 is a bona fide centriolar protein localizing to the very distal end of the centriole, where it associates with a pool of distal centrin. We also found that both proteins are recruited early during procentriole assembly and that depletion of SFI1 results in the specific loss of the distal pool of centrin, without altering centriole duplication in human cells, in contrast to its function for SPB. Instead, we found that SFI1/centrin complexes are essential for correct centriolar architecture as well as for ciliogenesis. We propose that SFI1/centrin complexes may guide centriole growth to ensure centriole integrity and function as a basal body.

cell biology↗

bioRxiv2019

The Evolutionary Dynamics of Cooperation in Collective Search

How does cooperation arise in an evolutionary context? We approach this problem using a collective search paradigm where interactions are dynamic and there is competition for rewards. Using evolutionary simulations, we find that the unconditional sharing of information can be an evolutionary advantageous strategy without the need for conditional strategies or explicit reciprocation. Shared information acts as a recruitment signal and facilitates the formation of a self-organized group. Thus, the improved search efficiency of the collective grants byproduct benefits to the original sharer by altering the interaction structure. A key mechanism is a visibility radius, where individuals have access to information about neighbors within a limited distance. Our results show that for a variety of initial conditions and across both static and dynamic fitness landscapes, there is strong selection pressure for unconditional sharing.

animal behavior and cognition↗

bioRxiv2018

Sharing is not erring: Pseudo-reciprocity in collective search

Information sharing in competitive environments may seem counterintuitive, yet it is widely observed in humans and other animals. For instance, the open-source software movement has led to new and valuable technologies being released publicly to facilitate broader collaboration and further innovation. What drives this behavior and under which conditions can it be beneficial for an individual? Using simulations in both static and dynamic environments, we show that sharing information can lead to individual benefits through the mechanisms of pseudo-reciprocity, whereby shared information leads to by-product benefits for an individual without the need for explicit reciprocation. Crucially, imitation with a certain level of innovation is required to avoid a tragedy of the commons, while the mechanism of a local visibility radius allows for the coordination of self-organizing collectives of agents. When these two mechanisms are present, we find robust evidence for the benefits of sharing--even when others do not reciprocate.

animal behavior and cognition↗