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The Pleiomorphic Plant MTOC:An Evolutionary Perspective

Journal of Integrative Plant Biology 2007年第8期49卷 1142-1153页

作者： RoyC.Brown bettye.lemmon Department of Biology University of Louisiana-LafayetteLafayetteLA 70504USA

γ-Tubulin is an essential component of the microtubule organizing center （MTOC） responsible for nucleating microtubules in both plants and animals. Whereas γ-tubulin is tightly associated with centrosomes that are inheritable organelles in cells of animals and most algae, it appears at different times and places to organize the myriad specialized microtubule systems that characterize plant cells. We have traced the distribution of γ-tubulin through the cell cycle in representative land plants （embryophytes） and herein present data that have led to a concept of the pleiomorphic and migratory MTOC. The many forms of the plant MTOC at spindle organization constitute pleiomorphism, and stage-specific “migration” is suggested by the consistent pattern of redistribution of γ-tubulin during mitosis. Mitotic spindles may be organized at centriolar centrosomes （only in final divisions of spermatogenesis）, polar organizers （POs）, plastid MTOCs, or nuclear envelope MTOCs （NE-MTOCs）. In all cases, with the possible exception of centrosomes in spermatogenesis, the γ-tubulin migrates to broad polar regions and along the spindle fibers, even when it is initially a discrete polar entity. At anaphase it moves poleward, and subsequently migrates from polar regions （distal nuclear surfaces） into the interzone （proximal nuclear surfaces） where interzonal microtubule arrays and phragmoplasts are organized. Following cytokinesis, γ-tubulin becomes associated with nuclear envelopes and organizes radial microtubule systems （RMSs）. These may exist only briefly, before establishment of hoop-like cortical arrays in vegetative tissues, or they may be characteristic of interphase in syncytial systems where they serve to organize the common cytoplasm into nuclear cytoplasmic domains （NCDs）.

关键词： angiosperms bryophytes cell cycle life cycle microtubule mitosis γ-tubulin.

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What does “Disruptive” mean? Thoughts on the NIH SCI 2020 meeting

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Neural Regeneration Research 2019年第9期14卷 1527-1529页

作者： Vance P.lemmon The Miami Project to Cure Paralysis Department of Neurological SurgeryCenter for Computational Science Miller School of Medicine University of Miami

On September 12 and 13,2019,the National Institute of Neurological Disorders and Stroke(NINDS),Eunice Kennedy Shriver National Institute of Child Health and Human Development(NICHD),as well as other federal agencies and several private foundations sponsored a stake holder meeting at the National Institutes of Health(NIH)Bethesda campus with a provocative title:“SCI 2020:Launching a decade for disruption in spinal cord injury research”.Over the past decade,“disruptive”has become a cool buzz word for entrepreneurs to use to market their *** this context,disruptive means“innovative,ingenious,and unconventional”(typically definition#2 in online dictionaries).The hope is their new technology or business model is so powerful it will upend current technologies and come to dominate the market ***’s destruction of taxi companies worldwide is a leading example of being“disruptive”.

关键词： SCI NIH Kennedy Human hope has is

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Transformations of the Pleiomorphic Plant MTOC during Sporogenesis in the Hepatic Marchantia polymorpha

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Journal of Integrative Plant Biology 2007年第8期49卷 1244-1252页

作者： Roy C.Brown Betty E.lemmon Masaki Shimamura Department of Biology University of Louisiana-LafayetteLafayetteLA 70504USA Department of Biological ScienceGraduate School of ScienceHiroshima UniversityKagami-yamaHigashi-Hiroshima 739-8526Japan

Sporogenesis in the hepatic Marchantia polymorpha L. provides an outstanding example of the pleiomorphic nature of the plant microtubule organizing center （MTOC）. Microtubules are nucleated from γ-tubuUn in MTOCs that change form during mitosis and meiosis. Following entry of cells into the reproductive pathway of sporogenesis, successive rounds of mitosis give rise to packets of 4-16 sporocytes. Mitotic spindles are organized at discrete polar organizers （POs）, a type of MTOC that is unique to this group of early divergent land plants. An abrupt and radical transformation in microtubule organization occurs when sporocytes enter meiosis： POs are lost and γ-tubulin is closely associated with surfaces of two large elongated plastids that subsequently divide into four. Migration of the four plastid MTOCs into a tetrahedral arrangement establishes the future spore domains and the division polarity of meiosis. As is typical of many bryophytes, cones of microtubules from the four plastid MTOCs initiate a quadripolar microtubule system （QMS） in meiotic prophase. At this point a transformation in the organization of the MTOCs occurs. The γ-tubulin detaches from plastids and forms a diffuse spheroidal pole in each of the spore domains. The plastids, which are no longer MTOCs, continue to divide. The diffuse MTOCs continue to nucleate cones of microtubules during transformation of the QMS to a bipolar spindle. Following meiosis I, γ-tubulin is associated with nuclear envelopes, and the spindles of meiosis II are organized from diffuse MTOCs at the tetrad poles. At simultaneous cytokinesis, radial microtubule systems are organized at nuclear envelope MTOCs in each of the tetrad members.

关键词： bryophyte γ-tubulin meiosis microtubules mitosis MTOC.

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Asymptotic stabilization of dynamically quantized nonlinear systems in feedforward form

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控制理论与应用（英文版） 2010年第1期8卷 27-33页

作者： Qiang LING Michael D. lemmon Hai LIN Department of Automation University of Science and Technology of China Hefei Anhui 230027 China Department of Electrical Engineering University of Notre Dame Notre Dame IN 46556 USA Department of Electrical and Computer Engineering National University of Singapore Singapore 117576

This paper studies the stabilizability of an n-dimensional quantized feedforward nonlinear system. The state of that system is first quantized into a finite number of bits, and then sent through a digital network to the controller. We want to minimize the number of transmitted bits subject to maintaining asymptotic stability. In the prior literature, n bits are used to stabilize the n-dimensional system by assigning one bit to each state variable （dimension）. Under the stronger assumption of global Lipschitz continuity, this paper extends that result by stabilizing the system with a single bit. Its key contribution is a dynamic quantization policy which dynamically assigns the single bit to the most ＂important＂ state variable. Under this policy, the quantization error exponentially converges to 0 and the stability of the system can, therefore, be guaranteed. Because i is the minimum number of quantization bits （per sampling step）, the proposed dynamic quantization policy achieves the minimum stabilizable bit number for that n-dimensional feedforward nonlinear system.

关键词： Quantization Stability Nonlinear Feedforward

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Facilitating transparency in spinal cord injury studies using data standards and ontologies

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Neural Regeneration Research 2014年第1期9卷 6-7页

作者： Vance P.lemmon Saminda Abeyruwan Ubbo Visser John L.Bixby Department of Neurological Surgery University of Miami Miami Project to Cure Paralysis University of Miami Center for Computational Science University of Miami Department of Computer Science University of Miami Molecular&Cellular Pharmacology University of Miami

Progress in developing robust therapies for spinal cord injury （SCI）, trau- matic brain injury （TBI） and peripheral nerve injury has been slow. A great deal has been learned over the past 30 years regarding both the intrinsic factors and the environmental factors that regulate axon growth, but this large body of information has not yet resulted in clinically available thera- peutics. This therapeutic bottleneck has many root causes, but a consensus is emerging that one contributing factor is a lack of standards for experi- mental design and reporting. The absence of reporting standards, and even of commonly accepted definitions of key words, also make data mining and bioinformatics analysis of neural plasticity and regeneration difficult, if not impossible. This short review will consider relevant background and poten- tial solutions to this problem in the axon regeneration domain.

关键词： data Facilitating transparency in spinal cord injury studies using data standards and ontologies SCI

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Casein kinase signaling in axon regeneration

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Neural Regeneration Research 2016年第2期11卷 210-211页

作者： Nagi G.Ayad Jae K.Lee Vance P.lemmon The Center for Therapeutic Innovation The Miami Project to Cure Paralysis Department of Psychiatry and Behavioral SciencesUniversity of Miami The Miami Project to Cure Paralysis Department of NeurosurgeryUniversity of Miami

Recent studies suggest that cell cycle pathways may contain therapeutic targets important for *** example of this is the finding that the vertebrate cell cycle exploits proteolysis pathways,yet these activities persist in fully differentiated cells that have exited the cell cycle such as *** have known for some time that a ubiquitin ligase.

关键词： APC Casein kinase signaling in axon regeneration

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Exploiting kinase polypharmacology for nerve regeneration

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Neural Regeneration Research 2016年第1期11卷 71-72页

作者： Hassan Al-Ali John L.Bixby Vance P.lemmon Miami Project to Cure Paralysis University of Miami Center for Computational Science University of Miami Department of Neurological Surgery University of Miami Department of Molecular & Cellular Pharmacology University of Miami

The human central nervous system（CNS）has a markedly poor capacity for regenerating its axons following *** appears to be due to two main causes：1）a developmentally regulated decline in regenerative capacity within mature CNS neurons,and 2）the presence of biological components that constitute barriers to axon regeneration（e.g.,growth-inhibitory molecules）.

关键词： regeneration alterations mature markedly constitute regenerative barriers phenotypic similarity inhibit

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Genetically modifying transcription factors to promote CNS axon regeneration

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Neural Regeneration Research 2017年第5期12卷 737-738页

作者： Saloni T.Mehta John L.Bixby Vance P.lemmon Miami Project to Cure Paralysis University of Miami Miller School of Medicine Miami FL USA Center for Computational Science University of Miami Miller School of Medicine Miami FL USA Neurological Surgery University of Miami Miller School of Medicine Miami FL USA Molecular & Cellular Pharmacology University of Miami Miller School of Medicine Miami FL USA

Following injury to the central nervous system（CNS）,severed axons fail to regenerate and re-form functional ***,CNS neurons appear to lack the intrinsic ability to modify their gene expression patterns to activate a robust regenerative response,perhaps as a result of limited plasticity in the adult brain（Davis,2013）.On the other hand,

关键词： CNS gene Jun VP

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Treatment with analgesics after mouse sciatic nerve injury does not alter expression of wound healingassociated genes

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Neural Regeneration Research 2016年第1期11卷 144-149页

作者： Matt C.Danzi Dario Motti Donna L.Avison John L.Bixby Vance P.lemmon The Miami Project to Cure Paralysis University of MiamiLois Pope LIFE Center Department of Surgery Leonard M. Miller School of Medicine University of Miami Department of Neurological Surgery University of Miami Department of Molecular and Cellular Pharmacology University of Miami

Animal models of sciatic nerve injury are commonly used to study neuropathic pain as well as axon regeneration. Administration of post-surgical analgesics is an important consideration for animal welfare, but the actions of the analgesic must not interfere with the scientific goals of the experiment. In this study, we show that treatment with either buprenorphine or acetaminophen following a bilateral sciatic nerve crush surgery does not alter the expression in dorsal root ganglion（DRG） sensory neurons of a panel of genes associated with wound healing. These findings indicate that the post-operative use of buprenorphine or acetaminophen at doses commonly suggested by Institutional Animal Care and Use Committees does not change the intrinsic gene expression response of DRG neurons to a sciatic nerve crush injury, for many wound healing-associated genes. Therefore, administration of post-operative analgesics may not confound the results of transcriptomic studies employing this injury model.

关键词： acetaminophen analgesics axon buprenorphine dorsal root ganglia gene expression peripheral nerve injuries regeneration sciatic nerve wound healing

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Natatanuran frogs used the Indian Plate to step-stone disperse and radiate across the Indian Ocean

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National Science Review 2019年第1期6卷 10-14页

作者： Zhi-Yong Yuan Bao-Lin Zhang Christopher J.Raxworthy David W.Weisrock Paul M.Hime Jie-Qiong Jin Emily M.lemmon Alan R.lemmon Sean D.Holland Michelle L.Kortyna Wei-Wei Zhou Min-Sheng Peng Jing Che Elizabeth Prendini State Key Laboratory of Genetic Resources and Evolution Kunming Institute of Zoology Chinese Academy of Sciences Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China Ministry of Education Southwest Forestry University Kunming College of Life Science University of Chinese Academy of Sciences Department of Herpetology American Museum of Natural History Department of Biology University of Kentucky Biodiversity Institute University of Kansas Southeast Asia Biodiversity Research Institute Chinese Academy of Sciences Department of Biological Science Florida State University Department of Scientific Computing Florida State University Sino-Africa Joint Research Center Chinese Academy of Sciences Center for Excellence in Animal Evolution andGenetics Chinese Academy of Sciences

Investigating the evolutionary history of widespread higher taxa, subjected to multiple tectonic events, can provide evidence for or against various palaeogeographical models of early Earth history [1,2]. Contemporary biotic distributions have been strongly influenced by events associated with the breakup of Gondwana into present-day Africa,Antarctica, Australia, South America,Madagascar and India, during the Late Mesozoic and Early Palaeogene [2]. The fragmentation of Gondwana and subsequent tectonic drift ultimately allowed biotic exchanges between Laurasia and Gondwana [2,3], influencing the global distributions of many taxa.

关键词： In Natatanuran frogs used the Indian Plate to step-stone disperse and radiate across the Indian Ocean

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