Characterizing cortical myosin mini-filament regulation, length and its macroscopic implications in cytokinetic dynamics

Au cours de la cytokinèse, le génome dédoublé est compartimentalisé en deux cellules filles. L’anneau contractile, une structure dynamique, est constitué d’actine, myosine (NMY-II) et d’autres protéines accessoires. NMY-2 est le seul moteur protéique impliqué dans la contraction de l’anneau durant la cytokinèse. Depuis longtemps, il a été considéré que celle-ci glissait le long des filaments d’actine grâce à sa capacité de traction. Récemment, plusieurs études ont découvert que son activité réticulante joue un rôle en cytokinèse et il est connu que la NMY-2 peut s’assembler en filaments bipolaires à partir de dimères. Ainsi, nous postulons que leur dimension (nombre de moteurs ATPasiques) pourrait dicter leur contribution en activité motrice et réticulante. Afin de déterminer la composition des filaments corticaux de NMY-2, nous avons utilisé une technique d'imagerie de molécules individuelles à l’aide de la microscopie TIRF. J’ai trouvé à travers l’analyse statistique de la distribution des NMY-2 mesurés que les filaments sont assemblés à deux dimensions constantes: Des filaments composés de 20 dimères et 30 dimères. La kinase Rho est une activatrice de NMY-2 nécessaire pour les niveaux physiologiques de NMY-2 sur l’anneau contractile, pour des cinétiques et fermeture concentrique de l’anneau. La déplétion de RhoK augmente l’abondance relative des filaments de 20 dimères. Ainsi, RhoK pourrait réguler le recrutement de la NMY et aussi l’assemblage des filaments corticaux de NMY-2. De plus, à l’aide de la microscopie confocale à temps réel, j’ai trouvé que lors de la déplétion de RhoK, il se produit une réduction du recrutement et du délai d’initiation du sillon, une fermeture lente et une augmentation significative de la concentricité de l’anneau. De plus, j’ai mesuré des défauts dans l’organisation corticale de l’anneau contractile en patch. La déplétion de MRCK-1 n’affecte pas l’initiation du sillon, les cinétiques de fermeture, ou la fermeture concentrique de l’anneau. Paradoxalement, la déplétion de MRCK-1 augmente le recrutement cortical de NMY-2, mais quand depleté simultanément avec Rho-K il diminue NMY-2 à l’équateur comparé à la déplétion seule de Rho-K. De plus, la double déplétion, conduit à un phénotype de concentricité de l’anneau, suivie d’un recentrage.Non-muscle myosin II (myosin) is important for many cellular processes, including cytokinesis. Myosin is a major component of the contractile ring, which constricts to close the connection between the two daughter cells. It was long accepted that actomyosin contractile filament sliding closes the cytokinetic ring. However, several recent papers conclude that myosin’s actin crosslinking activity is more important than its motor activity. These two functions likely relate to the number of actin-binding heads per bipolar myosin mini-filament. I then measured the size of cortical bipolar myosin mini-filaments and tested how mini-filament size and abundance influences cytokinesis. To measure the composition of individual myosin-containing cortical features, I developed a TIRF microscopy-based assay to calculate the number of NMY-2 dimers per feature from a ratio of endogenous/functional NMY-2-GFP. Interestingly control cells possess 2 populations: mini-filaments with an average of 20 dimers and with 30 dimers that are built to consistent specifications. Depletion of the NMY-2 activator Rho-Kinase or Anillin, a contractile ring scaffold protein, significantly alters the relative abundance of small and larger NMY-2 filament populations. I then tested the macroscopic implications of perturbations that alter cortical NMY-2 assembly. I measured NMY-2 regulators depleted cells and measured NMY-2 cortical recruitment, organization, and the kinetics (speed and concentricity) of cytokinesis. Rho-K depletion decreases NMY-II cortical recruitment and organization, slows ring closure and makes it more concentric. Depletion of MRCK-1, a less well-understood conserved myosin kinase, increased myosin cortical recruitment but had little effect on furrowing kinetics. Following simultaneous depletion of MRCK and RhoK, cortical myosin organization and recruitment were drastically reduced and, as expected for a much weaker cortex, a unique concentric phenotype emerged. Thus, while Rho-kinase is the more important kinase for myosin activation, MRCK-1 contributes to myosin organization and contractile ring dynamics. We conclude that myosin is recruited to the cortex as multi-headed mini-filaments whose assembly is tightly regulated and which impacts several aspects of contractile ring function

Impact of Wire Rod Rolling Mill Mechanisation on Job Requirements

THE present investigation has the purpose of identifying the effects of mechanisation on the work force requir-ements in the steel rolling mill plants.In order that this study will not add,to the confusion or be ascribed an importance beyond its validity,the whole framework of the investigation will be considered before proceeding. The labour aspects of mechanisation will be invest-igated only as they are encountered in the restricted area of the steel rod rolling mill plants. We shall consider what happens to labour requirements under increasing mechanisation only in three plants repre-senting different stages of mechanisation which are chara- cterising the technological development of this kind of rolling plants.1 In this way the mechanisation effect alone could be isolated with the consideration of the jobs change through the three rolling plants. It is not correct to assume that this study represents an experience on the impact of auto-matic machinery oil labour outside the restricted area in which the data are collected. The usefulness of the present examination lies there-fore in revealing patterns of experience with automation that may be typical of rod rolling mill development, and in identifying their effect on the work force requirements

The effects of a plant-based diet on diabetes mellitus

Diabetes is a global epidemic that has unfortunately been significantly increasing in number of cases annually. It is currently the 7th leading cause of death in the United States and leads to many further complications including cardiovascular disease, neuropathy, retinopathy, and kidney failure. With the increase in Western dietary patterns there has been a subsequent rise in both obesity and diabetes. In fact, type 2 diabetes makes up 90% of diabetes cases and is, in most cases, preventable with lifestyle changes and weight loss. The aim of this review is to look at the option of a plant-based diet as a means of prevention and treatment for type 2 diabetes. In order to understand type 2 diabetes the basics of pathophysiology, risk factors, statistic, complications and current treatments is discussed. Based on an analysis of a low-fat, plant-based diet compared to current conventional type 2 diabetes treatments there is evidence that a vegan diet increases insulin sensitivity, decreases body weight, lowers cardiovascular risk factors, and decreases need for oral antidiabetic treatments. A review of the efficacy of a plant-based diet for treatment and prevention of type 2 diabetes is also discussed in-depth. Further studies may be helpful to validate adopting a low-fat, plant-based diet in treatment of type 2 diabetes. Overall, it is important for physicians to address the individual needs of their patients and allow for the option of lifestyle changes with adequate guidance and support

Predicting successful clinical candidates for fiducial-free lung tumor tracking with a deep learning binary classification model

Robotic radiosurgery allows for marker-less lung tumor tracking by detecting tumor density variations in 2D orthogonal X-ray images. The ability to detect and track a lung lesion depends on its size, density, and location, and has to be evaluated on a case-by-case basis. The current method for identifying which patient can be successfully treated with fiducial-free lung tumor tracking is a time-consuming process named Lung Optimized Treatment (LOT) simulation. The process involves CT acquisition, generation of a simulation plan, creation of the patient breathing model, and execution of the simulation plan on the treatment delivery platform. The aim of the study is to develop a tool to enable binary classification of trackable and non-trackable lung tumors for automatic selection of optimal tracking methods for patient undergoing robotic radiosurgery without having to perform the LOT simulation. We developed a deep learning classification model and tested 5 different network architectures to classify lung cancer lesions from enhanced digitally reconstructed radiographs (DRRs) generated from planning CTs. This study included 129 patients with single or multiple lesions, for a total of 144 lung lesions (n=115 trackable, n=29 untrackable). A total of 271 images were included in our analysis. We kept 80% of the images for training, 10% for validation, and the remaining 10% for testing. The binary classification accuracy reached 100% after training, both in the validation and the test set. Candidates for fiducial-free lung tumor tracking during robotic lung radiosurgery can be successfully identified by using a deep learning model classifying DRR images sourced from simulation CT scans.Comment: 19 pages, 7 figure

MAP1B and S-nitrosylation in axon guidance, glial cell function and neurodegeneration

Die Aktivierung der neuronalen Stickoxidsynthase (nNOS) in dorsalen Wurzelganglion (DRG) Neuronen führt zu Axonretraktion die abhängig von MAP1B S Nitrosylierung ist1. Um zu untersuchen ob dieser Mechanismus auch in klassischen Signaltransduktionswegen der Axonführung wichtig ist, erforschte ich die Rolle von MAP1B und NO in den Netrin-1- und Semaphorin3A-Signaltransduktionswegen. Netrin-1 wird an der Mittellinie des sich entwickelnden zentralen Nervensystems exprimiert und kann, je nach extrazellulärer Umgebung, entweder anziehend oder abstossend auf Nervenzellen wirken. Zum Beispiel wurde gezeigt, dass die Verfügbarkeit von Laminin bestimmt ob Netrin-1 attraktiv oder repulsiv agiert2. Ausserdem scheint MAP1B wichtig für die korrekte Interpretierung des attraktiven Netrin-1 Signals3 und die Axonführung über die Mittelllinie im Mausvorderhirn4. Bindung von Netrin-1 an seinen Rezeptor induziert einen Kalziumeinstrom welcher eventuell nNOS aktivieren könnte. Im ersten Teil meiner Dissertation erforschte ich die Rolle von nNOS, NO und MAP1B in Netrin-1-Axonführung. Ich analysierte das Verhalten von neuronalen Wachstumskegeln von Wildtyp und MAP1B-/- DRG Neuronen auf Laminin und die morphologischen Veränderungen, sowie die Bildung von intrazellulärem NO nach einer Behandlung mit Netrin-1. Die quantitative Analyse zeigte, dass Netrin-1 in Wildtyp sowie in MAP1B-/- DRG Neuronen einen signifikanten Anstieg in Axonretraktion hervorruft, was wiederum annehmen lässt, dass MAP1B im repulsiven Netrin-1 Signalweg keine Rolle spielen dürfte. Nach der Behandlung mit Netrin-1 wurde in Wildtyp und MAP1B-/- DRG Neuronen ein starker Anstieg in der Produktion von NO beobachtet. Die stärkste Konzentration an NO war in kollapierten Wachstumskegeln und zurückgezogenen Axonen zu sehen. Das weist darauf hin, dass durch den Netrin-1 induzierten Kalziumeinstrom eine NOS aktiviert wird. Mithilfe spezifischer NOS-Inhibitoren konnte ich zeigen, dass in Wildtyp DRG Neuronen nNOS und in MAP1B-/- DRG Neuronen endotheliale NOS (eNOS) durch Netrin-1 aktiviert werden. Dieser Unterschied kommt daher, dass in MAP1B-/- DRG Neuronen nNOS-Expression stark hinunterreguliert ist. Diese Resultate deuten auf eine neue Rolle von nNOS und NO in Netrin-1 Axonführung hin. Die NO-Synthese kann zwei Effekte bewirken: zum Ersten die S-Nitrosylierung von Protein oder die Aktivierung des sGMP Signalweges. Da meine Resultate zeigen, dass die S-Nitrosylierung von MAP1B nicht essenziell im repulsiven Netrin-1 Signalweg ist, untersuchte ich den cGMP Signalweg etwas genauer. Dafür verwendete ich spezifische Inhibitoren für soluble Guanylyl Cyclase (sGC), ODQ und LY83583. Die Inhibierung von sGC verhinderte nicht die Netrin-1 induzierte Axonretraktion. Stattdessen führte die Inhibierung von sGC per se zu einer rapiden, MAP1B-abhängigen Axonretraktion. Dieses Resultat weist darauf hin, dass ein negativer Feedbackmechanismus, der zuvor beschrieben wurde5, in der Tat in DRG Neuronen auftritt. Demnach bewirkt NO die cGMP-Synthese, diese aktiviert PKG welche nNOS phosphoryliert und deaktiviert. Durch die Inhibierung der sGC wird dieser negative Feedbackmechanismus ausgeschaltet und nNOS bleibt aktiv und synthetisiert weiterhin NO, welches letztendlich zu MAP1B-abhängiger Axonretraktion führte. Übereinstimmend damit konnte ich zeigen, dass sGC Inhibitor-induzierte Axonretraktion nicht in MAP1B-/- Neuronen auftritt und, dass die Retraktion in Wildtypneuronen durch NPA verhindert werden kann, welche die Inhibierung von nNOS durch PKG nachahmt. Um herauszufinden, ob NO Synthese auch im Semaphorin3A Signalweg eine Rolle spielt, kultivierte ich Explantate von Hippocampus und DRGs in Wachstumsmedium welches Semaphorin3A und/oder NOS Inhibitoren enthielt. Diese Experimente gaben einen klaren Hinweis darauf, dass NO in der Tat wichtig für den repulsiven Semaphorin3A Mechanismus ist. Im zweiten Teil meiner Dissertation interessierte ich mich für die Rolle von MAP1B in Oligodendrozyten. MAP1B Expression geht der terminalen Differenzierung dieser Zellen voran und wurde in Oligodendrozyten beobachtet, die kurz davor stehen, Axone zu myelinisieren6. Es wurde mehrmals postuliert, dass NO in Oligodendrozytenschädigungen und in der Demyelinisierung im Laufe von Krankheiten wie Multipler Sklerose involviert ist7. Daher stellt sich die Frage, ob MAP1B als Mediator der NO-Toxizität in diesen Zellen dienen könnte. Ausserdem wurde gezeigt, dass MAP1B für den Transport von mRNA in DRG Neuronen wichtig ist. Da der mRNA-Transport zur Zellperipherie essenziell für die Etablierung einer Myelinschicht ist, wollte ich die Wichtigkeit von MAP1B in diesen Zellen untersuchen. Überraschenderweise differenzierten MAP1B-/- Zellen in vitro normal. Oligodendrozyten zeigten auch keine Reaktion auf eine Behandlung mit hochkonzentrierten NO-Donoren. Andererseits bewirkte die Stimulierung eines Kalziumeinstroms, welcher NOS aktiviert, einen Kollaps des Zytoskeletts. Dieser Kollaps konnte teilweise durch die Inhibierung von nNOS in Wildtyp und eNOS in MAP1B-/- Zellen verhindert werden. Ich nehme daher an, dass in Oligodendrozyten, wie in Neuronen, ein Unterschied im NOS Expressionsschema zu finden ist. Ausserdem zeigen die Resultate, dass NOS und NO in der Tat toxisch auf Oligodendrozyten wirken und das Zytoskelett beeinflussen.Activation of neuronal nitric oxide synthase (nNOS) in dorsal root ganglia (DRG) neurons leads to axon retraction dependent on S-nitrosylation of microtubule associated protein 1B (MAP1B). These findings raised the question whether this mechanism is involved in classical axon guidance signaling, for example in response to the guidance cues netrin-1 and semaphorin3A. Netrin-1 is expressed at the midline of the developing central nervous system and can act as attractive or repulsive cue, depending on the environmental context. The absence or presence of laminin in the extracellular matrix determines whether netrin-1 triggers attraction or repulsion, respectively. On the other hand, it has been shown that MAP1B is necessary for the proper transduction of the attractive netrin-1 signal and for axon guidance across the midline in the murine forebrain. Netrin-1 guidance involves calcium influx and could lead to nNOS activation. In the first part of my PhD thesis, I investigated the role of nNOS, NO and MAP1B in netrin-1 guidance. I analyzed growth cone behaviour of wild-type and MAP1B-/- DRG neurons on laminin and monitored the morphological changes upon netrin-1 treatment and intracellular NO synthesis. The analysis of the response of wild-type and MAP1B-/- DRG neurons to netrin-1 revealed a significant increase of retracted neurons after the incubation with netrin-1 in both cell types suggesting that MAP1B is not relevant for repulsive netrin-1 signaling in DRG neurons. Moreover, after netrin-1 treatment, a striking increase in the production of intracellular NO could be observed in wild-type and MAP1B-/- DRG neurons. The highest concentration of NO was seen in the collapsed growth cones of retracted axons. This result suggests that the Ca2+ influx induced by netrin-1 activates a NOS. With the help of specific NOS inhibitors I could show that in wild-type DRG neurons nNOS was activated downstream of netrin-1, whereas in MAP1B-/- DRG neurons it was endothelial NOS (eNOS). This difference in the downstream target of netrin-1 was due to a greatly reduced expression of nNOS in MAP1B-/- DRG neurons. These results demonstrate a novel role for nNOS and NO in netrin-1 mediated axon guidance. The production of NO following netrin-1 treatment can affect two possible downstream effectors: protein-S-nitrosylation or the cGMP pathway. Since my results indicate that S-nitrosylation of MAP1B is probably not essential for netrin-1 repulsion, the cGMP pathway was investigated in more detail. For this purpose the specific inhibitors for soluble guanylyl cyclase (sGC), ODQ and LY83583 were used. However, the inhibition of sGC did not prevent netrin-1 induced retraction. Instead, inhibitions of sGC per se lead to rapid, MAP1B-dependent axon retraction and an increase in NO synthesis. This indicates that a negative feedback mechanism, which was previously suggested by results obtained in vitro, is indeed at work in DRG neurons. According to this model, NO triggers cGMP synthesis, which in turn will activate cGMP-dependent kinase (PKG) to phosphorylate and thereby inactivate nNOS. By inhibiting sGC, this negative feedback mechanism is shut down and nNOS continues to produce NO which will finally lead to MAP1B dependent axon retraction. Consistent with this model, I could show that sGC inhibitor induced axon retraction is not observed in MAP1B-/- Neurons and can be prevented in wild-type neurons by NPA, which mimicked inhibition of nNOS by PKG. In order to analyze whether NO might also play a role in the semaphorin3A pathway, I grew explants from hippocampus and DRGs in media supplemented with semaphorin3A in the presence of NOS inhibitors. I obtained strong evidence that NO production might indeed be involved in repulsive semaphorin3A signaling. In the second part of my PhD thesis I was interested in the role of MAP1B in oligodendrocytes. MAP1B expression precedes terminal differentiation of and was observed in oligodendrocytes that initiate ensheathment of axons6. NO has been postulated to play a role in oligodendrocyte damage and myelin loss in multiple sclerosis7. This raised the question whether MAP1B might be a mediator of the highly toxic effect of NO to oligodendrocytes. Moreover, it was suggested that MAP1B plays a role in the transport of mRNA in DRG neurons. As the transport of mRNAs to the cell periphery is essential for the establishment of myelin bearing sheaths during terminal oligodendrocyte differentiation, I investigated the role of MAP1B in these cells. Surprisingly, in vitro oligodendrocyte differentiation was normal in MAP1B-/- cells. Moreover, oligodendrocytes did not show any reaction when treated with NO donors at high concentrations suggesting a lower susceptibility to NO than expected. In contrast, stimulation of calcium influx in oligodendrocytes triggered a NOS-dependent collapse of the cytoskeleton. This collapse could be partially prevented by inhibition of nNOS in wild-type and eNOS in MAP1B-/- cells suggesting that in oligodendrocytes, as in neurons, lack of MAP1B changes the NOS expression pattern. These results show that NOS and NO can indeed be toxic to oligodendrocytes, affecting their cytoskeleton

The effect of group size on vigilance in a semi-solitary, fossorial marsupial (Lasiorhinus latifrons)

Prey species that congregate gain protection against predatory attacks and this advantage is often reflected by a reduction in vigilance behaviour by individuals in larger groups. Comparatively few studies have investigated vigilance in solitary animals, but those that have, found that vigilance increases as group size increases because of the threat posed by conspecifics and/or competition for resources. The southern hairy nosed wombat (Lasiorhinus latifrons) is a large fossorial, nocturnal marsupial that is neither strictly solitary nor gregarious, sharing warren systems with multiple conspecifics. We investigated the effects of conspecific presence on vigilance behaviour in this semi-solitary species. We observed wild-born, adult L. latifrons wombats in three group sizes, (Large (1♂, 3♀), Medium (1♂, 2♀) and Small (1♂, 1♀) in a captive, naturalistic environment that allowed above-ground and den behaviour monitoring. Vigilance behaviours were performed less frequently by wombats in large groups (e.g. scanning, counts/day, Large: 55, Medium: 69, Small: 115, P = 0.002) and more frequently as the distance from their nearest conspecific increased (r64 = 0.30, P = 0.016). Vigilance within burrows was also affected by social influences, with solitary wombats significantly more vigilant than those denning with a conspecific (e.g. scanning: conspecific absent: 0.13 / 5 min, present: 0.03/ 5 min, P < 0.0001). It is concluded that the presence of conspecifics reduces vigilance in L. latifrons wombats, even within burrows, and this may partially explain the occurrence of warren sharing in the wild

Investigating the clinical advantages of a robotic linac equipped with a multileaf collimator in the treatment of brain and prostate cancer patients.

The purpose of this study was to evaluate the performance of a commercially available CyberKnife system with a multileaf collimator (CK-MLC) for stereotactic body radiotherapy (SBRT) and standard fractionated intensity-modulated radiotherapy (IMRT) applications. Ten prostate and ten intracranial cases were planned for the CK-MLC. Half of these cases were compared with clinically approved SBRT plans generated for the CyberKnife with circular collimators, and the other half were compared with clinically approved standard fractionated IMRT plans generated for conventional linacs. The plans were compared on target coverage, conformity, homogeneity, dose to organs at risk (OAR), low dose to the surrounding tissue, total monitor units (MU), and treatment time. CK-MLC plans generated for the SBRT cases achieved more homogeneous dose to the target than the CK plans with the circular collimators, for equivalent coverage, conformity, and dose to OARs. Total monitor units were reduced by 40% to 70% and treatment time was reduced by half. The CK-MLC plans generated for the standard fractionated cases achieved prescription isodose lines between 86% and 93%, which was 2%-3% below the plans generated for conventional linacs. Compared to standard IMRT plans, the total MU were up to three times greater for the prostate (whole pelvis) plans and up to 1.4 times greater for the intracranial plans. Average treatment time was 25 min for the whole pelvis plans and 19 min for the intracranial cases. The CK-MLC system provides significant improvements in treatment time and target homogeneity compared to the CK system with circular collimators, while maintaining high conformity and dose sparing to critical organs. Standard fractionated plans for large target volumes (>100 cm3) were generated that achieved high prescription isodose levels. The CK-MLC system provides more efficient SRS and SBRT treatments and, in select clinical cases, might be a potential alternative for standard fractionated treatments. PACS numbers: 87.56.nk, 87.56.bd

Respiration-Induced Intraorgan Deformation of the Liver: Implications for Treatment Planning in Patients Treated With Fiducial Tracking.

Stereotactic body radiation therapy is a well-tolerated modality for the treatment of primary and metastatic liver lesions, and fiducials are often used as surrogates for tumor tracking during treatment. We evaluated respiratory-induced liver deformation by measuring the rigidity of the fiducial configuration during the breathing cycle. Seventeen patients, with 18 distinct treatment courses, were treated with stereotactic body radiosurgery using multiple fiducials. Liver deformation was empirically quantified by measuring the intrafiducial distances at different phases of respiration. Data points were collected at the 0%, 50%, and 100% inspiration points, and the distance between each pair of fiducials was measured at the 3 phases. The rigid body error was calculated as the maximum difference in the intrafiducial distances. Liver disease was calculated with Child-Pugh score using laboratory values within 3 months of initiation of treatment. A peripheral fiducial was defined as within 1.5 cm of the liver edge, and all other fiducials were classified as central. For 5 patients with only peripheral fiducials, the fiducial configuration had more deformation (average maximum rigid body error 7.11 mm, range: 1.89-11.35 mm) when compared to patients with both central and peripheral and central fiducials only (average maximum rigid body error 3.36 mm, range: 0.5-9.09 mm, P = .037). The largest rigid body errors (11.3 and 10.6 mm) were in 2 patients with Child-Pugh class A liver disease and multiple peripheral fiducials. The liver experiences internal deformation, and the fiducial configuration should not be assumed to act as a static structure. We observed greater deformation at the periphery than at the center of the liver. In our small data set, we were not able to identify cirrhosis, which is associated with greater rigidity of the liver, as predictive for deformation. Treatment planning based only on fiducial localization must take potential intraorgan deformation into account

Background reduction and sensitivity for germanium double beta decay experiments

Germanium detectors have very good capabilities for the investigation of rare phenomena like the neutrinoless double beta decay. Rejection of the background entangling the expected signal is one primary goal in this kind of experiments. Here, the attainable background reduction in the energy region where the neutrinoless double beta decay signal of 76Ge is expected to appear has been evaluated for experiments using germanium detectors, taking into consideration different strategies like the granularity of the detector system, the segmentation of each individual germanium detector and the application of Pulse Shape Analysis techniques to discriminate signal from background events. Detection efficiency to the signal is affected by background rejection techniques, and therefore it has been estimated for each of the background rejection scenarios considered. Finally, conditions regarding crystal mass, radiopurity, exposure to cosmic rays, shielding and rejection capabilities are discussed with the aim to achieve a background level of 10-3 c keV-1 kg-1 y-1 in the region of interest, which would allow to explore neutrino effective masses around 40 meV.Comment: 13 pages, 19 figures. Accepted by Astroparticle Physic

Roles of AGS3 in epithelial morphogenesis and oral carcinogenesis

Oriented cell divisions balance self-renewal and differentiation in stratified epithelia such as the skin epidermis. During peak epidermal stratification, the distribution of division angles among basal keratinocyte progenitors is bimodal, with planar and perpendicular divisions driving symmetric and asymmetric daughter cell fates, respectively. An apically-polarized, evolutionarily-conserved spindle orientation complex that includes the scaffolding protein LGN/Pins/Gpsm2 plays a central role in promoting perpendicular divisions and stratification, but little is known about the molecular regulation of planar divisions. Here, we demonstrate that the LGN paralog, AGS3/Gpsm1, is a novel negative regulator of LGN, and inhibits perpendicular divisions. Static and ex vivo live imaging reveal that AGS3 overexpression displaces LGN from the apical cortex and increases planar orientations, while AGS3 loss prolongs cortical LGN localization and leads to a perpendicular orientation bias. Genetic epistasis experiments in double mutants confirm that AGS3 operates through LGN. Finally, clonal lineage tracing shows that LGN and AGS3 promote asymmetric and symmetric fates, respectively, while also influencing differentiation through delamination. Collectively, these studies shed new light into how spindle orientation influences epidermal stratification.Doctor of Philosoph