Luis G. Morelli

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The segmentation clock is an oscillating genetic network thought to govern the rhythmic and sequential subdivision of the elongating body axis of the vertebrate embryo into somites: the precursors of the segmented vertebral column. Understanding how the rhythmic signal arises, how it achieves precision and how it patterns the embryo remain challenging(More)
BACKGROUND Coupled biological oscillators can tick with the same period. How this collective period is established is a key question in understanding biological clocks. We explore this question in the segmentation clock, a population of coupled cellular oscillators in the vertebrate embryo that sets the rhythm of somitogenesis, the morphological(More)
Rhythmic and sequential subdivision of the elongating vertebrate embryonic body axis into morphological somites is controlled by an oscillating multicellular genetic network termed the segmentation clock. This clock operates in the presomitic mesoderm (PSM), generating dynamic stripe patterns of oscillatory gene-expression across the field of PSM cells. How(More)
During vertebrate embryogenesis, the rhythmic and sequential segmentation of the body axis is regulated by an oscillating genetic network termed the segmentation clock. We describe a new dynamic model for the core pace-making circuit of the zebrafish segmentation clock based on a systematic biochemical investigation of the network's topology and precise(More)
We study a model of associative memory based on a neural network with small-world structure. The efficacy of the network to retrieve one of the stored patterns exhibits a phase transition at a finite value of the disorder. The more ordered networks are unable to recover the patterns, and are always attracted to mixture states. Besides, for a range of the(More)
The effectiveness of below-the-knee PTA to obtain successful revascularization in patients with critical limb ischemia (CLI) has been well established, and many centers have adopted endovascular intervention as the first-line treatment in patients with chronic lower-extremity disease. The well-known complex and multilevel arterial disease in patients with(More)
We study general aspects of active motion with fluctuations in the speed and the direction of motion in two dimensions. We consider the case in which fluctuations in the speed are not correlated to fluctuations in the direction of motion, and assume that both processes can be described by independent characteristic time scales. We show the occurrence of a(More)
We analyze the synchronization transition for a pair of coupled identical Kauffman networks in the chaotic phase. The annealed model for Kauffman networks shows that synchronization appears through a transcritical bifurcation and provides an approximate description for the whole dynamics of the coupled networks. We show that these analytical predictions are(More)
We develop a stochastic description of feedback oscillators in which functional molecules are produced by an assembly line consisting of many identical steps. The initiation rate of this assembly is regulated by its products via a negative feedback. This model is motivated by genetic oscillators such as circadian clocks. We show that precise oscillations of(More)
lysis, suggesting that MurJ function, and thus PG synthesis, was inhibited (Fig. 2 and fig. S5). In contrast, treatment of MurJ cells with MTSES caused cell shape defects and limited lysis indicative of an incomplete PG synthesis block due to partialMurJ inhibition. The toxicity of MTSES labeling was suppressed in all five strains by the presence of the(More)