Nephi Stella

University of Washington Seattle, Seattle, Washington, United States

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Publications (89)659.23 Total impact

  • Neuro-Oncology 11/2015; 17(suppl 5):v19-v19. DOI:10.1093/neuonc/nov204.06 · 5.56 Impact Factor
  • Susan Fung · Allison E Cherry · Cong Xu · Nephi Stella ·
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    ABSTRACT: Ligands targeting G protein-coupled receptors (GPCR) expressed by microglia have been shown to regulate distinct components of their activation process, including cell proliferation, migration and differentiation into M1 or M2 phenotypes. Cannabinoids, including the active component of the Cannabis plant, tetrahydrocannabinol (THC), and the synthetic alkylindole (AI) compound, WIN55212-2 (WIN-2), activate two molecularly identified GPCRs: CB1 and CB2 . Previous studies reported that WIN-2 activates an additional unknown GPCR that is not activated by plant-derived cannabinoids, and evidence indicates that microglia express these receptors. Detailed studies on the role of AI-sensitive receptors in microglial cell activation were difficult as no selective pharmacological tools were available. Here, three newly-developed AI analogues allowed us to determine if microglia express AI-sensitive receptors and if so, study how they regulate the microglial cell activation process. We found that mouse microglia in primary culture express functional AI-sensitive receptors as measured by radioligand binding and changes in intracellular cAMP levels, and that these receptors control both basal and ATP-stimulated migration. AI analogues inhibit cell proliferation stimulated by macrophage-colony stimulating factor (M-CSF) without affecting basal cell proliferation. Remarkably, AI analogues do not control the expression of effector proteins characteristic of M1 or M2 phenotypes; yet activating microglia with M1 and M2 cytokines reduces the microglial response to AI analogues. Our results suggest that microglia express functional AI-sensitive receptors that control select components of their activation process. Agonists of these novel targets might represent a novel class of therapeutics to influence the microglial cell activation process. GLIA 2015. © 2015 Wiley Periodicals, Inc.
    Glia 04/2015; 63(10). DOI:10.1002/glia.22845 · 6.03 Impact Factor
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    ABSTRACT: The type 2 cannabinoid receptors (CB2R) have gained much attention recently due to their important regulatory role in a host of pathophysiological processes. However, the exact biological function of CB2R and how this function might change depending on disease progression remains unclear and could be better studied with highly sensitive and selective imaging tools for identifying the receptors. Here we report the first near infrared fluorescence imaging probe (NIR760-XLP6) that binds preferentially to CB2R over the type 1 cannabinoid receptors (CB1R). The selectivity of the probe was demonstrated by fluorescence microscopy using DBT-CB2 and DBT-CB1 cells. Furthermore, in mouse tumor models, NIR760-XLP6 showed significantly higher uptake in DBT-CB2 than that in DBT-CB1 tumors. These findings indicate that NIR760-XLP6 is a promising imaging tool for the study of CB2R regulation. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Biomaterials 04/2015; 57:169-178. DOI:10.1016/j.biomaterials.2015.04.018 · 8.56 Impact Factor
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    ABSTRACT: One of the major signs of severe organophosphate poisoning is seizures. Previous studies have shown that both muscarinic agonist- and organophosphate-induced seizures require activation of muscarinic acetylcholine receptors in the central nervous system. Seizures induced by the muscarinic agonist pilocarpine require the M1 receptor and are modulated by cannabinoid CB1 receptors. In this study, we determined whether M1 and CB1 receptors also regulated seizures induced by the organophosphate paraoxon. We found no differences in seizures induced by paraoxon in wild-type (WT) and M1 knockout (KO) mice, indicating that in contrast to pilocarpine seizures, M1 receptors are not required for paraoxon seizures. Furthermore, we found that pilocarpine administration resulted in seizure-independent activation of ERK in the hippocampus in a M1 receptor-dependent manner, while paraoxon did not induce seizure-independent activation of ERK in the mouse hippocampus. This shows that pilocarpine and paraoxon activated M1 receptors in the hippocampus to different extents. There were no differences in seizures induced by paraoxon in WT and CB1 KO mice, and neither CB1 agonist nor antagonist administration had significant effects on paraoxon seizures, indicating that, in contrast to pilocarpine seizures, paraoxon seizures are not modulated by CB1 receptors. These results demonstrate that there are fundamental molecular differences in the regulation of seizures induced by pilocarpine and paraoxon.
    02/2015; 3(1). DOI:10.1002/prp2.100
  • Vincenzo Di Marzo · Nephi Stella · Andreas Zimmer ·
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    ABSTRACT: Ageing is characterized by the progressive impairment of physiological functions and increased risk of developing debilitating disorders, including chronic inflammation and neurodegenerative diseases. These disorders have common molecular mechanisms that can be targeted therapeutically. In the wake of the approval of the first cannabinoid-based drug for the symptomatic treatment of multiple sclerosis, we examine how endocannabinoid (eCB) signalling controls - and is affected by - normal ageing and neuroinflammatory and neurodegenerative disorders. We propose a conceptual framework linking eCB signalling to the control of the cellular and molecular hallmarks of these processes, and categorize the key components of endocannabinoid signalling that may serve as targets for novel therapeutics.
    Nature reviews Neuroscience 12/2014; 16(1):30-42. DOI:10.1038/nrn3876 · 31.43 Impact Factor
  • Allison E Cherry · Nephi Stella ·
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    ABSTRACT: Gliomas are the most common malignant intracranial tumors. Newly developed targeted therapies for these cancers aim to inhibit oncogenic signals, many of which emanate from receptor tyrosine kinases, including the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor receptor (VEGFR). Unfortunately, the first generation treatments targeting these oncogenic signals provide little survival benefit in both mouse xenograft models and human patients. The search for new treatment options has uncovered several G protein-coupled receptor (GPCR) candidates and generated a growing interest in this class of proteins as alternative therapeutic targets for the treatment of various cancers, including GBM. GPCRs constitute a large family of membrane receptors that influence oncogenic pathways through canonical and non-canonical signaling. Accordingly, evidence indicates that GPCRs display a unique ability to crosstalk with receptor tyrosine kinases, making them important molecular components controlling tumorigenesis. This review summarizes the current research on GPCR functionality in gliomas and explores the potential of modulating these receptors to treat this devastating disease.
    Neuroscience 08/2014; 278(1). DOI:10.1016/j.neuroscience.2014.08.015 · 3.36 Impact Factor
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    ABSTRACT: Cannabinoids affect immune responses in ways that may be beneficial for autoimmune diseases. We sought to determine whether chronic Cannabis use differentially modulates a select number of immune parameters in healthy controls and individuals with multiple sclerosis (MS cases). Subjects were enrolled and consented to a single blood draw, matched for age and BMI. We measured monocyte migration isolated from each subject, as well as plasma levels of endocannabinoids and cytokines. Cases met definition of MS by international diagnostic criteria. Monocyte cell migration measured in control subjects and individuals with MS was similarly inhibited by a set ratio of phytocannabinoids. The plasma levels of CCL2 and IL17 were reduced in non-naïve cannabis users irrespective of the cohorts. We detected a significant increase in the endocannabinoid arachidonoylethanolamine (AEA) in serum from individuals with MS compared to control subjects, and no significant difference in levels of other endocannabinoids and signaling lipids irrespective of Cannabis use. Chronic Cannabis use may affect the immune response to similar extent in individuals with MS and control subjects through the ability of phytocannabinoids to reduce both monocyte migration and cytokine levels in serum. From a panel of signaling lipids, only the levels of AEA are increased in individuals with MS, irrespective of Cannabis use or not. Our results suggest that both MS cases and controls respond similarly to chronic Cannabis use with respect to the immune parameters measured in this study.
    Inflammopharmacology 08/2014; 22(5). DOI:10.1007/s10787-014-0214-z
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    ABSTRACT: Huntington's disease (HD) is caused by an expanded polyglutamine repeat in huntingtin protein that disrupts synaptic function in specific neuronal populations and results in characteristic motor, cognitive and affective deficits. Histopathological hallmarks observed in both HD patients and genetic mouse models include the reduced expression of synaptic proteins, reduced medium spiny neuron (MSN) dendritic spine density and decreased frequency of spontaneous excitatory post-synaptic currents (sEPSCs). Early down-regulation of cannabinoid CB1 receptor expression on MSN (CB1(MSN)) is thought to participate in HD pathogenesis. Here we present a cell-specific genetic rescue of CB1(MSN) in R6/2 mice and report that treatment prevents the reduction of excitatory synaptic markers in the striatum (synaptophysin, vGLUT1 and vGLUT2), of dendritic spine density on MSNs and of sEPSCs, but does not prevent motor impairment. We conclude that loss of excitatory striatal synapses in HD mice is controlled by CB1(MSN) and can be uncoupled from the motor phenotype.
    Neurobiology of Disease 08/2014; 71. DOI:10.1016/j.nbd.2014.08.009 · 5.08 Impact Factor
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    ABSTRACT: BACKGROUND The endocannabinoid system regulates cancer cell proliferation, and in prostate cancer a high cannabinoid CB1 receptor expression is associated with a poor prognosis. Down-stream mediators of CB1 receptor signaling in prostate cancer are known, but information on potential upstream regulators is lacking. RESULTS Data from a well-characterized tumor tissue microarray were used for a Bayesian network analysis using the max-min hill-climbing method. In non-malignant tissue samples, a directionality of pEGFR (the phosphorylated form of the epidermal growth factor receptor) → CB1 receptors were found regardless as to whether the endocannabinoid metabolizing enzyme fatty acid amide hydrolase (FAAH) was included as a parameter. A similar result was found in the tumor tissue, but only when FAAH was included in the analysis. A second regulatory pathway, from the growth factor receptor ErbB2 → FAAH was also identified in the tumor samples. Transfection of AT1 prostate cancer cells with CB1 receptors induced a sensitivity to the growth-inhibiting effects of the CB receptor agonist CP55,940. The sensitivity was not dependent upon the level of receptor expression. Thus a high CB1 receptor expression alone does not drive the cells towards a survival phenotype in the presence of a CB receptor agonist. CONCLUSIONS The data identify two potential regulators of the endocannabinoid system in prostate cancer and allow the construction of a model of a dysregulated endocannabinoid signaling network in this tumor. Further studies should be designed to test the veracity of the predictions of the network analysis in prostate cancer and other solid tumors. Prostate 74:1107–1117, 2014. © 2014 The Authors. The Prostate published by Wiley Periodicals, Inc.
    The Prostate 08/2014; 74(11). DOI:10.1002/pros.22827 · 3.57 Impact Factor
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    ABSTRACT: The serine hydrolase α/β-hydrolase domain 6 (ABHD6) hydrolyzes the most abundant endocannabinoid (eCB) in the brain, 2-arachidonoylglycerol (2-AG), and controls its availability at cannabinoid receptors. We show that ABHD6 inhibition decreases pentylenetetrazole (PTZ)-induced generalized tonic-clonic and myoclonic seizure incidence and severity. This effect is retained in Cnr1(-/-) or Cnr2(-/-) mice, but blocked by addition of a subconvulsive dose of picrotoxin, suggesting the involvement of GABAA receptors. ABHD6 inhibition also blocked spontaneous seizures in R6/2 mice, a genetic model of juvenile Huntington's disease known to exhibit dysregulated eCB signaling. ABHD6 blockade retained its antiepileptic activity over chronic dosing and was not associated with psychomotor or cognitive effects. While the etiology of seizures in R6/2 mice remains unsolved, involvement of the hippocampus is suggested by interictal epileptic discharges, increased expression of vGLUT1 but not vGAT, and reduced Neuropeptide Y (NPY) expression. We conclude that ABHD6 inhibition may represent a novel antiepileptic strategy.
    Neuron 07/2014; 83(2):361-371. DOI:10.1016/j.neuron.2014.06.030 · 15.05 Impact Factor
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    ABSTRACT: Administration of the muscarinic agonist pilocarpine is commonly used to induce seizures in rodents for the study of epilepsy. Activation of muscarinic receptors has been previously shown to increase the production of endocannabinoids in the brain. Endocannabinoids act at the cannabinoid CB1 receptors to reduce neurotransmitter release and the severity of seizures in several models of epilepsy. In this study, we determined the effect of CB1 receptor activity on the induction in mice of seizures by pilocarpine. We found that decreased activation of the CB1 receptor, either through genetic deletion of the receptor or treatment with a CB1 antagonist, increased pilocarpine seizure severity without modifying seizure-induced cell proliferation and cell death. These results indicate that endocannabinoids act at the CB1 receptor to modulate the severity of pilocarpine-induced seizures. Administration of a CB1 agonist produced characteristic CB1-dependent behavioral responses, but did not affect pilocarpine seizure severity. A possible explanation for the lack of effect of CB1 agonist administration on pilocarpine seizures, despite the effects of CB1 antagonist administration and CB1 gene deletion, is that muscarinic receptor-stimulated endocannabinoid production is acting maximally at CB1 receptors to modulate sensitivity to pilocarpine seizures.
    PLoS ONE 04/2014; 9(4):e95922. DOI:10.1371/journal.pone.0095922 · 3.23 Impact Factor
  • Susan Fung · Nephi Stella ·
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    ABSTRACT: Glioblastoma multiforme (GBM) is the most common form of primary brain tumor and is diagnosed in approximately 15,000 people each year in the United States alone. No cure for this type of cancer exists, and the current standard of care treatments provide little benefit and are associated with debilitating side effects. Recent evidence shows that a large number of tumor-associated macrophages (TAMs) invade the GBM tumor mass and secrete factors that directly and indirectly promote tumor growth. TAMs express a panel of unique receptors that could be targeted for therapeutic benefit. One such receptor, cannabinoid receptor 2 (CB2), is a member of the endocannabinoid (eCB) signaling system, and its activation has been shown to tightly control the migration and phenotype of both macrophages and microglia. Additional receptors, also engaged by eCBs and cannabinoid-like compounds, are expressed by macrophages and microglia. These receptors also control cell migration and phenotype, but exhibit distinct pharmacological profiles and operate through a different mechanism of action. Strong evidence accumulated over the past decade indicates that membrane receptors expressed by TAMs represent novel targeting opportunities to treat GBM tumor progression. Here we review studies that significantly increased our understanding of the molecular mechanism of action of receptors engaged by eCBs and cannabinoid-like compounds expressed by GBM tumor cells and TAMs. This evidence provides a strong rationale for developing new therapeutics that target the eCB signaling of TAMs for the treatment of GBM while minimizing the typical side effects associated with standard care. WIREs Membr Transp Signal 2014. doi: 10.1002/wmts.101 Conflict of interest: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.
    03/2014; 3(2). DOI:10.1002/wmts.101
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    ABSTRACT: PHARC (polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataracts) is a recently described autosomal-recessive neurodegenerative disease caused by mutations in the α-β-hydrolase domain-containing 12 gene (ABHD12). Only five homozygous ABHD12 mutations have been reported and the pathogenesis of PHARC remains unclear. We evaluated a woman who manifested short stature as well as the typical features of PHARC. Sequence analysis of ABHD12 revealed a novel heterozygous c.1129A>T (p.Lys377X) mutation. Targeted comparative genomic hybridization detected a 59-kb deletion that encompasses exon 1 of ABHD12 and exons 1-4 of an adjacent gene, GINS1, and includes the promoters of both genes. The heterozygous deletion was also carried by the patient's asymptomatic mother. Quantitative reverse transcription-PCR demonstrated ∼50% decreased expression of ABHD12 RNA in lymphoblastoid cell lines from both individuals. Activity-based protein profiling of serine hydrolases revealed absence of ABHD12 hydrolase activity in the patient and 50% reduction in her mother. This is the first report of compound heterozygosity in PHARC and the first study to describe how a mutation might affect ABHD12 expression and function. The possible involvement of haploinsufficiency for GINS1, a DNA replication complex protein, in the short stature of the patient and her mother requires further studies. This article is protected by copyright. All rights reserved.
    Human Mutation 12/2013; 34(12). DOI:10.1002/humu.22437 · 5.14 Impact Factor
  • Nephi Stella ·
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    ABSTRACT: Delta9-tetrahydrocannabinol (THC), the principal bioactive component in the Cannabis plant, is truly a captivating drug. Acute and chronic THC intake produces a spectrum of biological effects ranging from transient psychotropic effects to prolonged medicinal benefits, many of which have been fostered for centuries by our society. In the July 2013 issue of the JCI, Cutando et al. combined mouse genetics with classic mouse behavioral analysis to deepen our understanding of the physiological consequence of subchronic THC intake on eyeblink reflexes, a fundamental neuronal adaptive response, revealing that this regimen leads to downregulation of the cannabinoid CB1 receptor (referred to as CB1 in the Cutando et al. article) in cerebellar stress fibers and the activation of microglia, raising provocative new questions about the safety profile of regimented THC intake.
    The Journal of clinical investigation 07/2013; 123(8). DOI:10.1172/JCI70226 · 13.22 Impact Factor
  • Mary E. Abood · Roger G Sorensen · Nephi Stella ·

  • Mary E. Abood · Roger G. Sorensen · Nephi Stella ·
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    ABSTRACT: For centuries the plants Cannabis sativa and Cannabis indica (commonly known as marijuana) have been used for recreational, religious, and medicinal purposes across diverse cultures. The first recorded attributes of Cannabis were on its potent therapeutic actions, which included analgesic, sedative, and anticonvulsant effects. In the 1930s Cannabis extracts were one of the most commonly prescribed medicines of the US pharmacopeia. Unfortunately, the early criminalization of the use of Cannabis resulted in a near 35-year stall in scientific research aimed at understanding and optimizing the therapeutic potential of its extracts. It was the isolation and chemical characterization of ∆9-tetrahydrocannabinol (THC) in 1964 as the first bioactive ingredient produced by Cannabis that revived the scientific community’s interest in further understanding and optimizing the unique therapeutic properties of phytocannabinoids (phyto-CB) (Mechoulam and Gaoni 1967).
    endoCANNABINOIDS, 01/2013: pages 263-280; , ISBN: 978-1-4614-4668-2
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    ABSTRACT: Peripheral immune cells and brain microglia exhibit an activated phenotype in premanifest Huntington's disease (HD) patients that persists chronically and correlates with clinical measures of neurodegeneration. However, whether activation of the immune system contributes to neurodegeneration in HD, or is a consequence thereof, remains unclear. Signaling through cannabinoid receptor 2 (CB(2)) dampens immune activation. Here, we show that the genetic deletion of CB(2) receptors in a slowly progressing HD mouse model accelerates the onset of motor deficits and increases their severity. Treatment of mice with a CB(2) receptor agonist extends life span and suppresses motor deficits, synapse loss, and CNS inflammation, while a peripherally restricted CB(2) receptor antagonist blocks these effects. CB(2) receptors regulate blood interleukin-6 (IL-6) levels, and IL-6 neutralizing antibodies partially rescue motor deficits and weight loss in HD mice. These findings support a causal link between CB(2) receptor signaling in peripheral immune cells and the onset and severity of neurodegeneration in HD, and they provide a novel therapeutic approach to treat HD.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 12/2012; 32(50):18259-18268. DOI:10.1523/JNEUROSCI.4008-12.2012 · 6.34 Impact Factor
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    Nephi Stella ·
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    ABSTRACT: Inflammation in the zebrafish brain stimulates neurogenesis and tissue regeneration.
    Science 12/2012; 338(6112):1303-4. DOI:10.1126/science.1232331 · 33.61 Impact Factor
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    ABSTRACT: Cannabinoid receptor 1 (CB(1) receptor) controls several neuronal functions, including neurotransmitter release, synaptic plasticity, gene expression and neuronal viability. Downregulation of CB(1) expression in the basal ganglia of patients with Huntington's disease (HD) and animal models represents one of the earliest molecular events induced by mutant huntingtin (mHtt). This early disruption of neuronal CB(1) signaling is thought to contribute to HD symptoms and neurodegeneration. Here we determined whether CB(1) downregulation measured in patients with HD and mouse models was ubiquitous or restricted to specific striatal neuronal subpopulations. Using unbiased semi-quantitative immunohistochemistry, we confirmed previous studies showing that CB(1) expression is downregulated in medium spiny neurons of the indirect pathway, and found that CB(1) is also downregulated in neuropeptide Y (NPY)/neuronal nitric oxide synthase (nNOS)-expressing interneurons while remaining unchanged in parvalbumin- and calretinin-expressing interneurons. CB(1) downregulation in striatal NPY/nNOS-expressing interneurons occurs in R6/2 mice, Hdh(Q150/Q150) mice and the caudate nucleus of patients with HD. In R6/2 mice, CB(1) downregulation in NPY/nNOS-expressing interneurons correlates with diffuse expression of mHtt in the soma. This downregulation also occludes the ability of cannabinoid agonists to activate the pro-survival signaling molecule cAMP response element-binding protein in NPY/nNOS-expressing interneurons. Loss of CB(1) signaling in NPY/nNOS-expressing interneurons could contribute to the impairment of basal ganglia functions linked to HD.
    European Journal of Neuroscience 11/2012; 37(3). DOI:10.1111/ejn.12045 · 3.18 Impact Factor
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    ABSTRACT: In Huntington disease (HD), immune cells are activated before symptoms arise; however, it is unclear how the expression of mutant huntingtin (htt) compromises the normal functions of immune cells. Here we report that primary microglia from early postnatal HD mice were profoundly impaired in their migration to chemotactic stimuli, and expression of a mutant htt fragment in microglial cell lines was sufficient to reproduce these deficits. Microglia expressing mutant htt had a retarded response to a laser-induced brain injury in vivo. Leukocyte recruitment was defective upon induction of peritonitis in HD mice at early disease stages and was normalized upon genetic deletion of mutant htt in immune cells. Migration was also strongly impaired in peripheral immune cells from pre-manifest human HD patients. Defective actin remodeling in immune cells expressing mutant htt likely contributed to their migration deficit. Our results suggest that these functional changes may contribute to immune dysfunction and neurodegeneration in HD, and may have implications for other polyglutamine expansion diseases in which mutant proteins are ubiquitously expressed.
    The Journal of clinical investigation 11/2012; 122(12). DOI:10.1172/JCI64484 · 13.22 Impact Factor

Publication Stats

7k Citations
659.23 Total Impact Points


  • 2002-2015
    • University of Washington Seattle
      • • Department of Psychiatry and Behavioral Sciences
      • • Department of Pharmacology
      Seattle, Washington, United States
  • 2001
    • University of California, Irvine
      • Department of Pharmacology
      Irvine, California, United States
  • 1997-2000
    • The Neurosciences Institute
      La Jolla, California, United States
    • French Institute of Health and Medical Research
      Lutetia Parisorum, Île-de-France, France
  • 1996
    • Collège de France
      • Center for Interdisciplinary Research in Biology
      Lutetia Parisorum, Île-de-France, France