Human Frontier Science Program Research Articles

Model updating of flowering snapdragon (Antirrhinum litigiosum) biomechanical responses to vibro-acoustic stimuli

The combined variation in gene expression and environmental conditions during flower development can result in phenotypic differences in shape, size, and material composition. Biomechanical responses in flower organs due to external stimuli can be mechanically measured at various levels. Here, we investigate snapdragon (Antirrhinum litigiosum) response to vibro-acoustic stimuli by an interdisciplinary model updating framework. In a climate-controlled setup, sweep signals and artificial signals representative of plant pollinator species were given as excitation input through a loudspeaker to a set of plants; vibrations of the flower organs were measured by laser Doppler vibrometry. Geometric features of the plants were identified using LiDAR combined with photogrammetry, while the density distribution in the flower organs and internal dimensions were estimated using micro-computed tomography scans. A computer model using finite element method was used to identify material properties of the flower organs by combining time domain measurements and dimensional classification. Results demonstrate density and stiffness gradient in the corolla contributing to a modal activity that is adaptive to local conditions and pollinators, but resilient against external noise. The framework outlined herein may give clues to which pollinators induce early-plant responses. [The authors acknowledge the support of the Human Frontier Science Program (HFSP) grant RGP0003/2022.]

Mechanical transmission of dengue virus by Aedes aegypti may influence disease transmission dynamics during outbreaks.

Dengue virus outbreaks are increasing in number and severity worldwide. Viral transmission is assumed to require a minimum time period of viral replication within the mosquito midgut. It is unknown if alternative transmission periods not requiring replication are possible. We used a mouse model of dengue virus transmission to investigate the potential of mechanical transmission of dengue virus. We investigated minimal viral titres necessary for development of symptoms in bitten mice and used resulting parameters to inform a new model of dengue virus transmission within a susceptible population. Naïve mice bitten by mosquitoes immediately after they took partial blood meals from dengue infected mice showed symptoms of dengue virus, followed by mortality. Incorporation of mechanical transmission into mathematical models of dengue virus transmission suggest that this supplemental transmission route could result in larger outbreaks which peak sooner. The potential of dengue transmission routes independent of midgut viral replication has implications for vector control strategies that target mosquito lifespan and suggest the possibility of similar mechanical transmission routes in other disease-carrying mosquitoes. This study was funded by grants from the National Health Research Institutes, Taiwan (04D2-MMMOST02), the Human Frontier Science Program (RGP0033/2021), the National Institutes of Health (1R01AI143698-01A1, R01AI151004 and DP2AI152071) and the Ministry of Science and Technology, Taiwan (MOST104-2321-B-400-016).

Chemotherapy delivery time affects treatment outcomes of female patients with diffuse large B-cell lymphoma.

Chronotherapy is a drug intervention at specific times of the day to optimize efficacy and minimize adverse effects. Its value in hematologic malignancy remains to be explored, in particular in adult patients. We performed chronotherapeutic analysis using two cohorts of diffuse large B cell lymphoma (DLBCL) patients undergoing chemotherapy with a dichotomized schedule (morning or afternoon). The effect of a morning or afternoon schedule of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) on survival and drug tolerability were evaluated in a survival cohort (n = 210) and an adverse event cohort (n = 129), respectively. Analysis of ~14,000 healthy subjects was followed to identify the circadian variation in hematologic parameters. Both progression-free survival (PFS) and overall survival (OS) of female, but not male, patients were significantly shorter when patients received chemotherapy mostly in the morning (PFS hazard ratio [HR] 0.357; P = 0.033 and OS HR 0.141; P = 0.032). The dose intensity was reduced in female patients treated in the morning (cyclophosphamide 10%; P = 0.002, doxorubicin 8%; P = 0.002 and rituximab 7%; P = 0.003). This was mainly attributable to infection and neutropenic fever: female patients treated in the morning suffered from a higher incidence of infections (16.7% vs 2.4%) and febrile neutropenia (20.8% vs 9.8%) as compared to those treated in the afternoon. The sex-specific chronotherapeutic effects can be explained by the larger daily fluctuation of circulating leukocytes and neutrophils in females than in males. In female DLBCL patients, R-CHOP treatment in the afternoon can reduce the toxicity while it improves the efficacy and the survival outcome.

Cell scientist to watch – Martin Loose

ABSTRACT Martin Loose studied chemistry at the University of Heidelberg, Germany. He then joined Petra Schwille's group at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, where he obtained his PhD degree in 2010 for work on self-organization and pattern formation in the bacterial Min protein system. He then moved to Tim Mitchison's lab at Harvard Medical School, Boston, USA for his postdoc, funded by Human Frontier Science Program (HSFP) and European Molecular Biology Organization (EMBO) long-term fellowships; there, he discovered that the bacterial cell division proteins FtsA and FtsZ self-organize into dynamic cytoskeletal patterns. Martin established his independent research group at the Institute of Science and Technology (IST) Austria in 2015, supported by an European Research Council (ERC) starting grant and HFSP Young Investigator Grant. His lab studies the self-organization of bacterial cell division and small GTPase networks.

Vocal learning in animals and humans.

Vocal learning in animals and humans.

028 Sleep loss disrupts hippocampal memory consolidation via an acetylcholine- and somatostatin interneuron-mediated inhibitory gate

Abstract Introduction Sleep loss profoundly disrupts consolidation of hippocampus-dependent memory. To better characterize effects of learning and sleep loss on the hippocampal circuit, we quantified activity-dependent phosphorylation of ribosomal subunit S6 (pS6) across the dorsal hippocampus of mice. Methods We first measured pS6 throughout the hippocampus after learning (single trial contextual fear conditioning; CFC), and after subsequent sleep or sleep deprivation (SD). To characterize cell populations with activity affected by SD, we used translating ribosome affinity purification (TRAP)-seq to identify cell type-specific transcripts on pS6 ribosomes after SD vs. sleep. We next used pharmacogenetics to mimic the effects of SD, selectively activating hippocampal Sst+ interneurons or cholinergic inputs to hippocampus from the medial septum (MS) while mice slept in the hours following CFC. We also inhibited these neuronal populations to assess effects on memory consolidation. Results We find that pS6 in enhanced in the dentate gyrus (DG) following single-trial CFC, but is reduced throughout the hippocampus after brief SD – a manipulation which disrupts contextual fear memory (CFM) consolidation. Cell type-specific enrichment analysis (CSEA) of these transcripts revealed that hippocampal somatostatin-expressing (Sst+) interneurons, and cholinergic and orexinergic inputs to hippocampus, are selectively activated after SD. We used TRAP targeted to hippocampal Sst+ interneurons to identify cellular mechanisms mediating SD-driven Sst+ interneuron activation. . We find that activation of Sst+ interneurons is sufficient to disrupt CFM consolidation, by gating activity in surrounding pyramidal neurons, while inhibition of Sst+ interneurons enhances memory consolidation. Similarly, pharmacogenetic activation of cholinergic input to hippocampus from the MS disrupted CFM. Inhibition of MS cholinergic neurons promoted CFM consolidation and disinhibited neurons in the DG, increasing pS6 expression among DG granule cells. Conclusion Our data suggest that state-dependent gating of DG activity during SD is mediated by cholinergic input. Together these data provide evidence for an inhibitory gate on hippocampal information processing, which is activated by sleep loss. Support (if any) R01-NS118440 to SJA from NINDS, DP2-MH104119 to SJA from the NIH Director’s Office, and a Human Frontiers Science Program Young Investigator Award

A conserved role of CBP/p300 in mitochondrial stress response and longevity

Caenorhabditis elegans respond to mitochondrial stress by activating multiple stress defense pathways including the mitochondrial unfolded protein response (UPRmt). Here we show that the inhibition of CBP‐1, the C. elegans ortholog of mammalian acetyltransferases CBP/p300, either through RNA interference or by pharmacological inhibitors, robustly attenuates mitochondrial perturbation‐ induced UPRmt activation and lifespan extension. Mechanistically, CBP‐1‐mediated histone acetylation acts in conjunction with histone demethylation to transcriptionally induce a broad spectrum of UPRmt genes. In mouse and human, transcript levels of CBP/p300 systematically correlate with the expression of UPRmt genes and mitochondrial modules, as well as with longevity. Furthermore, loss‐of‐function of CBP/p300 or their pharmacological inhibition disrupts the activation of the UPRmt, the mitochondrial network and energy homeostasis in mammalian cells. These results highlight an evolutionary conserved epigenetic mechanism that protects mitochondrial function and regulates longevity through the histone acetyltransferases CBP/p300.Support or Funding InformationThis work was supported by grants from the Ecole Polytechnique Fédérale de Lausanne and the European Research Council (ERC‐AdG‐787702). T.Y.L. was supported by the “Human Frontier Science Program” (LT000731/2018‐L).

DNA-Origami-Assisted Flow-Aligned Single-Particle Diffractive Imaging using XFEL Pulses

Outrunning radiation damage, highly intense femtosecond pulses of X-ray free-electron lasers (XFELs) open up the possibility of structure determination of macromolecules to viruses at room temperature, by aggregating diffraction patterns recorded from uncrystallized single-particles. A key challenge in XFEL single-particle diffractive imaging (SPI) is to either constrain the orientation of the particle or to determine it from each of the very noisy weak diffraction patterns. Here we report a unique approach to address these challenges using structural DNA nanotechnology. A DNA-origami “rigid tail” is site-specifically attached to the macromolecule to flow-align it in a thin liquid jet, and also provides a strong holographic reference. In a proof-of-principle study, the computational design and production of the DNA-origami-target construct has been achieved and the experimental results obtained from the Linac Coherent Light Source (LCLS), USA show the alignment of the target single-particle, consistent with simulations, at extremely low concentrations approaching single-molecule in the interaction region with the nanofocus hard X-ray laser beam, in a sum of as few as a thousand single-shots. The results open up the possibility of single-molecule diffractive imaging in solution with XFEL pulses. Acknowledgements: The Human Frontier Science Program (RGP0010/2017).

Great Footmark of the Late Professor Masao Ito: The Past and Future of the Japan Neuroscience Society

Professor Masao Ito passed away in December last year at the age of 90. He not only performed great scientific achievements in the studies of the cerebellar circuit functions, but also made a great contribution to promotion of the neuroscience researches both in and outside Japan. His contribution includes foundation of the Japan Neuroscience Society, RIKEN Brain Science Institute, working as the president of International Brain Research Organization, foundation of Human Frontier Science Program and foundation of federation of scientific associations in Asia such as FAONS.

Intraluminal Nutrients Modulate Intracellular Calcium Activity in the Enteric Nervous System of Adult Mice

BackgroundIt has long been hypothesized that enteric neurons are able to detect nutrients present in the intestinal lumen, but direct evidence in intact preparations of the intestine is lacking. Understanding how enteric neurons react to changes in dietary constituents will open new avenues for discoveries on the relation between nutrition, modulation of gut function, and health.AimTo measure neuronal activity in the enteric nervous system in response to luminal nutrients.MethodsWe have designed chambers allowing us to visualize, record and quantify intracellular calcium activity in 3D live‐cell confocal recordings of neurons from intact, whole thickness segments of mouse intestine. Twenty mice expressing the genetically encoded calcium reporter Gcamp6 under the control of the pan‐neuronal Wnt1 promoter were used to record intracellular calcium activity in neurons from the jejunum and colon, while perfusing different nutrients through the lumen. Krebs solution was perfused as control and Ensure®, 10% Intralipid® or 20mM Glucose were used as stimuli. 3D videos of calcium fluorescence in the neuronal network were acquired with a Nikon A1R confocal microscope and calcium dynamics were analyzed using the Imaris software (Bitplane). Results are expressed as relative changes in fluorescence intensity (ΔF/F) ± SEM among the neuronal populations studied.ResultsPerfusion of the intestine with Ensure® (liquid meal replacement) increased the fluorescence intensity in reactive neurons by 670 ± 270% in the jejunum and 403 ± 62% in the colon. Peak amplitude was measured on average 5–6 minutes after the initiation of the nutrient perfusion. Perfusion with 10% Intralipid® (lipid emulsion) increased the fluorescence intensity in reactive neurons by 300 ± 180% in the jejunum and 150 ± 15% in the colon. On the other hand, perfusion of the intestine with Glucose (20mM in Krebs solution) lowered baseline fluorescence intensity in a population of neurons by −91 ± 3% in the jejunum and −80 ± 3% in the colon. The percentage of neurons reacting to intraluminal stimuli was dependent on the stimulus and was different between the jejunum and the colon, indicating that subpopulations of neurons might differentially react to different nutrient stimuli.ConclusionsWe report the existence of slow intracellular calcium changes in the neurons in the intestine that vary depending on the nutrient content of the intestinal lumen. The origin and functional consequences of these changes in intracellular calcium activity as well as the identity of responding neurons are currently under investigation.Support or Funding InformationFunding sources: Canadian institutes of Health Research, Alberta Innovates, Human Frontier Science Program.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Disordered regions as regulators of phase transitions in multivalent proteins

This talk will present a synthesis of findings from theory, computation, and experiment highlighting the roles of intrinsically disordered regions as regulators and modulators of phase transitions for linear multivalent proteins. These phase transitions determine the organization, dynamics, and functions of membraneless organelles and other biomolecular condensates. The insights obtained are paving the way for designing condensates with bespoke sequence‐encoded phase behavior and material properties.Support or Funding InformationThis work is supported by the National Science Foundation, the National Institutes of Health, the Human Frontier Science Program, and the St. Jude Children's Research Hospital Research Collaborative.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

NUTRIENTS ACUTELY MODULATE INTESTINAL PERMEABILITY INDEPENDENTLY OF THE ENTERIC NERVOUS SYSTEM

BackgroundIt is well known that diet profoundly affects intestinal physiology, with some diets contributing to a “leaky gut”, possibly promoting IBD and metabolic syndrome. Recently, several studies have suggested that the enteric nervous system, composed of neurons and glial cells, could be a potent regulator of intestinal permeability. We hypothesize that nutrients, sensed at the level of the epithelium, could trigger a neuroglial response to regulate intestinal permeability.AimsWe investigated whether nutrients acutely modulate intestinal permeability at the level of the small intestine and if the enteric nervous system plays a role in this effect.MethodsIntact jejunum and Ileum segments from CD1 mice were mounted in Ussing chambers. Transepithelial electrical resistance (TER) and short circuit current (Isc) were recorded for 50 min after stimulation with different nutrients. Two different size probes, 400 Da Fluorescein isothiocyanate (FITC) or 4000 Da FITC‐Dextran (FD4), were used as markers of intestinal permeability. Apical glucose, fructose, glutamine (10 mM) or 5% Intralipid® were used as nutrient stimuli. Enteric neurons were either inhibited with tetrodotoxin (TTX, 0.5 μM) or activated with veratridine (10 μM). Enteric gliotransmission was inhibited with the connexin 43 blocker Gap26 (20 μM).ResultsThe nutrients used in this study were “sensed” by the intestinal epithelium as illustrated by a rapid change in Isc following stimulation (+14, +7, −28 μA/cm2 for glucose, glutamine and Intralipid, respectively, in the jejunum; +132, +42, −14, −56 μA/cm2 for glucose, glutamine, fructose and Intralipid in the ileum). Addition of 5% Intralipid to the luminal side increased TER in both jejunum (+10 Ω/cm2) and Ileum (+10 Ω/cm2). Glutamine triggered a significant (p<0.05) increase of the transport of FITC across the intestine (+600% in jejunum and +60% in ileum after 50 minutes). On the other hand the transport of both FITC and FD4 was significantly reduced in the presence of Intralipid (−73% and −27%, respectively, in the jejunum and −74% and −31%, in the ileum). Results were similar when germ free mice were compared to conventionally raised mice. Neither the activation or inhibition of enteric neurons or the inhibition of gliotransmission affected TER or the transport of the fluorescent probes across the mouse intestine. Additionally, the use of the neuronal blocker, TTX, did not reverse the glutamine‐ or Intralipid‐induced alteration of FITC and FD4 transport across the intestine. Blocking the calcium‐sensing receptor did not alter the response to glutamine.ConclusionsWe have shown glutamine and Intralipid® to be potent regulators of intestinal permeability acting independently of the enteric nervous system, the microbiota, and the calcium‐sensing receptor. We are currently investigating the potential endocrine contribution to these effects.Support or Funding InformationThe work of Dr. Cavin was supported by a postdoctoral fellowship from the Human Frontier Science Program Organization and Alberta innovates.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Funding knowledgebases: Towards a sustainable funding model for the UniProt use case.

Millions of life scientists across the world rely on bioinformatics data resources for their research projects. Data resources can be very expensive, especially those with a high added value as the expert-curated knowledgebases. Despite the increasing need for such highly accurate and reliable sources of scientific information, most of them do not have secured funding over the near future and often depend on short-term grants that are much shorter than their planning horizon. Additionally, they are often evaluated as research projects rather than as research infrastructure components. In this work, twelve funding models for data resources are described and applied on the case study of the Universal Protein Resource (UniProt), a key resource for protein sequences and functional information knowledge. We show that most of the models present inconsistencies with open access or equity policies, and that while some models do not allow to cover the total costs, they could potentially be used as a complementary income source. We propose the Infrastructure Model as a sustainable and equitable model for all core data resources in the life sciences. With this model, funding agencies would set aside a fixed percentage of their research grant volumes, which would subsequently be redistributed to core data resources according to well-defined selection criteria. This model, compatible with the principles of open science, is in agreement with several international initiatives such as the Human Frontiers Science Program Organisation (HFSPO) and the OECD Global Science Forum (GSF) project. Here, we have estimated that less than 1% of the total amount dedicated to research grants in the life sciences would be sufficient to cover the costs of the core data resources worldwide, including both knowledgebases and deposition databases.

Funding knowledgebases: Towards a sustainable funding model for the UniProt use case

Millions of life scientists across the world rely on bioinformatics data resources for their research projects. Data resources can be very expensive, especially those with a high added value as the expert-curated knowledgebases. Despite the increasing need for such highly accurate and reliable sources of scientific information, most of them do not have secured funding over the near future and often depend on short-term grants that are much shorter than their planning horizon. Additionally, they are often evaluated as research projects rather than as research infrastructure components. In this work, twelve funding models for data resources are described and applied on the case study of the Universal Protein Resource (UniProt), a key resource for protein sequences and functional information knowledge. We show that most of the models present inconsistencies with open access or equity policies, and that while some models do not allow to cover the total costs, they could potentially be used as a complementary income source. We propose the Infrastructure Model as a sustainable and equitable model for all core data resources in the life sciences. With this model, funding agencies would set aside a fixed percentage of their research grant volumes, which would subsequently be redistributed to core data resources according to well-defined selection criteria. This model, compatible with the principles of open science, is in agreement with several international initiatives such as the Human Frontiers Science Program Organisation (HFSPO) and the OECD Global Science Forum (GSF) project. Here, we have estimated that less than 1% of the total amount dedicated to research grants in the life sciences would be sufficient to cover the costs of the core data resources worldwide, including both knowledgebases and deposition databases.

Versatile Multiplexed Super-Resolution Imaging of Nanostructures by Quencher-Exchange-Paint

The work was supported by funding from the Human Frontier Science Program (No. 0027/2013) and the Engineering and Physical Sciences Research Council of the UK (No. EP/N008235/1).

Funding knowledgebases: Towards a sustainable funding model for the UniProt use case.

Millions of life scientists across the world rely on bioinformatics data resources for their research projects. Data resources can be very expensive, especially those with a high added value as the expert-curated knowledgebases. Despite the increasing need for such highly accurate and reliable sources of scientific information, most of them do not have secured funding over the near future and often depend on short-term grants that are much shorter than their planning horizon. Additionally, they are often evaluated as research projects rather than as research infrastructure components. In this work, twelve funding models for data resources are described and applied on the case study of the Universal Protein Resource (UniProt), a key resource for protein sequences and functional information knowledge. We show that most of the models present inconsistencies with open access or equity policies, and that while some models do not allow to cover the total costs, they could potentially be used as a complementary income source. We propose the Infrastructure Model as a sustainable and equitable model for all core data resources in the life sciences. With this model, funding agencies would set aside a fixed percentage of their research grant volumes, which would subsequently be redistributed to core data resources according to well-defined selection criteria. This model, compatible with the principles of open science, is in agreement with several international initiatives such as the Human Frontiers Science Program Organisation (HFSPO) and the OECD Global Science Forum (GSF) project. Here, we have estimated that less than 1% of the total amount dedicated to research grants in the life sciences would be sufficient to cover the costs of the core data resources worldwide, including both knowledgebases and deposition databases.

A pension fund for European scientists.

Scientists are part of a global community who freely exchange ideas and materials; many researchers are engaged in international cooperation and collaborative research projects. In fact, traveling and working abroad is not only a necessity; spending some time abroad as a graduate student, postdoc, or visiting scientist also boosts their careers. Studies that compared data from 16 countries concluded that foreign scientists often outperform their native colleagues and that they have larger international research networks [1], [2]. Generally, given that most scientific knowledge is the result of collaborative research performed in many countries, mobility is important for progress. Many transnational funding agencies—such as the European Research Council, the Marie Sklodowska‐Curie Actions or the Human Frontier Science Program—therefore stress or even require international mobility from their grantees. However, while mobility has its own benefits (even irrespective of a research project), there are also downsides of spending too much time working abroad. The greatest risk for scientists who spend an extensive period in another country is losing out on social security, in particular on pension rights in their home country. The 2005 European Charter for Researchers therefore urged its member states to pay particular attention to “the portability of pension rights, either statutory or supplementary, for researchers moving within the public and private sectors in the same country and also for those moving across borders within the European Union. Such regimes should guarantee that researchers who, in the course of their lives, change jobs or interrupt their careers do not unduly …

Cell scientist to watch – Emmanuel Boucrot

ABSTRACT Emmanuel Boucrot obtained an undergraduate and a master's degree in biochemistry at the University of Geneva in Switzerland. He pursued his PhD in immunology at the University of Aix-Marseille II in France, supervised by Stéphane Méresse in the laboratory of Jean-Pierre Gorvel. Emmanuel moved to the USA for his postdoctoral training in the laboratory of Tomas Kirchhausen at Harvard Medical School, first as an EMBO fellow and then as a Human Frontiers Science Program fellow. Before starting his own laboratory in 2011, Emmanuel held another postdoctoral position in the laboratory of Harvey McMahon at the MRC Laboratory of Molecular Biology in Cambridge, UK. He is a recipient of a Lister Institute Research Prize and a BBSRC David Phillips Research Fellowship. His group at University College London is interested in studying the mechanisms of clathrin-independent endocytosis, as well as investigating properties of quiescent cells.

A biofunctional microcavity platform to dissect autocrine and paracrine signals and to control fate decisions of hematopoietic stem and progenitor cells

Event Abstract Back to Event A biofunctional microcavity platform to dissect autocrine and paracrine signals and to control fate decisions of hematopoietic stem and progenitor cells Eike Müller1, Weiija Wang2, Wendy Qiao2, Martin Bornhäuser3, Peter W. Zandstra2, Carsten Werner1 and Tilo Pompe1, 4 1 Leibniz Institute of Polymer Research Dresden, Max Bergmann Center of Biomaterials, Germany 2 University of Toronto, Institute of Biomaterials and Biomedical Engineering, Canada 3 University Clinics Dresden, Germany 4 Universität Leipzig, Institute of Biochemistry, Germany Homeostasis of hematopoietic stem and progenitors cells (HSPC) in the mammalian bone marrow stem cell niche is regulated by signals of the local microenvironment. Besides juxtacrine, endocrine and metabolic cues, paracrine and autocrine signals are involved in controlling quiescence, proliferation and differentiation of HSPC over the whole mammalian lifetime. The still limited understanding of signaling pathways hinders ex vivo HSPC expansion and differentiation as well as tight control of HSPC engraftment in clinical transplantation. Previously, we demonstrated cell-sized micropatterns to maintain a quiescent, non-differentiated state of human HSPC in vitro[1],[2]. We now considerably expanded micropatterned substrates to a combinatorial microcavity platform involving biohybrid hydrogels besides surface-functionalized silicone materials. We used a new micropatterning approach to imprint cell-sized features in the poly(ethylene glycol) based hydrogels additionally containing biofunctional glycosaminoglycan and adhesion peptide features. The extensive analysis of a 7-day in vitro culture of CD34+ primary human HSPC involved quantification of cell proliferation and differentiation as well as expression analysis of many cytokines involved in HSPC regulation. A partial least square analysis of the multifactorial dataset was used to reveal relevant juxtacrine, paracrine and autocrine signals. Finally, in vivo experiments were performed to functionally validate the in vitro data in a mouse repopulation model. Our results show that the usage of the microcavity platform in combination with a partial least square analysis of a mechanistic model of cell proliferation allows to decipher autocrine versus paracrine signals of soluble factors in HSPC culture, which was not possible up to now in other in vitro and in vivo settings. Autocrine signals of RANTES and paracrine signals of IL12 were found as stimulating factors, while autocrine signals of HGF and paracrine signals of ANG2 gave an inhibitory function. Based on these findings we hypothesize autocrine signals to be predominantly involved in maintaining the quiescent state of HSPC in single-cell niches. Furthermore, the in vivo repopulation studies proved the HSPC maintaining effect of single-cell microcavities. We conclude, that the introduced microcavity platform combined with an in-depth analysis provides a new biotechnological tool to entangle convoluted signaling mechanisms in complex cell systems being it of juxtacrine, paracrine or autocrine origin. Specifically, it unraveled distinct autocrine and paracrine functions of cytokines in HSPC maintenance. Human Frontier Science Program (HFSP), Grant RGP0051/2011

Cell scientist to watch – Maya Schuldiner

Maya Schuldiner pursued her PhD degree under the guidance of Prof. Nissim Benvenisty at the Hebrew University in Jerusalem. She carried out her postdoctoral training in the laboratory of Prof. Jonathan Weissman at the University of California, San Francisco, with support from the Human Frontiers Science Program and the Sandler Fellows Program. Since 2008, Maya has been running her own laboratory at the Weizmann Institute of Sciences in Rehovot, Israel. She received the Human Frontiers Science Program Career Development Award and the NIH Pathway to Independence Award, and she is a member of the EMBO Young Investigator programme and Faculty of 1000. Her current research interests are focused on unravelling novel functions of yeast proteins that are involved in organelle biology.