電顕でtime-lapse

Science 2010; 328:187 - 193

Four-Dimensional Electron Microscopy

Ahmed H. Zewail

The discovery of the electron over a century ago and the realization of its dual character have given birth to one of the two most powerful imaging instruments: the electron microscope. The electron microscope’s ability to resolve three-dimensional (3D) structures on the atomic scale is continuing to affect different fields, including materials science and biology. In this Review, we highlight recent developments and inventions made by introducing the fourth dimension of time in electron microscopy. Today, ultrafast electron microscopy (4D UEM) enables a resolution that is 10 orders of magnitude better than that of conventional microscopes, which are limited by the video-camera rate of recording. After presenting the central concept involved, that of single-electron stroboscopic imaging, we discuss prototypical applications, which include the visualization of complex structures when unfolding on different length and time scales. The developed UEM variant techniques are several, and here we illucidate convergent-beam and near-field imaging, as well as tomography and scanning-pulse microscopy. We conclude with current explorations in imaging of nanomaterials and biostructures and an outlook on possible future directions in space-time, 4D electron microscopy.

＝＝＝

生体材料で本当に電顕－計時観察が実現すると、かなりたくさんのことがわかりそうな気がする。

Proc Natl Acad Sci U S A. 2010;107(8):3829-33

Thalamic deactivation at sleep onset precedes that of the cerebral cortex in humans.

Magnin M, Rey M, Bastuji H, Guillemant P, Mauguiere F, Garcia-Larrea L.

Thalamic and cortical activities are assumed to be time-locked throughout all vigilance states. Using simultaneous intracortical and intrathalamic recordings, 

we demonstrate here that the thalamic deactivation occurring at sleep onset most often precedes that of the cortex by several minutes, whereas reactivation of both structures during awakening is synchronized. Delays between thalamus and cortex deactivations can vary from one subject to another when a similar cortical region is considered. In addition, heterogeneity in activity levels throughout the cortical mantle is larger than previously thought during the descent into sleep. Thus, asynchronous thalamo-cortical deactivation while falling asleep probably explains the production of hypnagogic hallucinations by a still-activated cortex and the common self-overestimation of the time needed to fall asleep.

＝＝＝

●入眠時にThalamusのほうがcortexより活動が早く（数分～数十分）ことを、ヒト検体を用いて検証。覚醒時はほぼ同時。

●the dimention of activation (DA)という、波形解析のアルゴリズムを用いて脳波を解析→大きな同期性徐波が出る睡眠時は数値が低下、ランダムで細かな波がでる覚醒時は数値が増加

fMRIによる、ヒト脳の機能的マップ

Nature Methods 7, 253 (2010) 

"A new study, pooling brain-imaging data from 35 centers across the world, shows the power of data sharing and demonstrates a universal architecture of functional connections in the human brain."

該当サイトはこちら。

Dev Biol. 331:210-21, 2009

Active cell movements coupled to positional induction are involved in lineage segregation in the mouse blastocyst.

In the mouse blastocyst, some cells of the inner cell mass (ICM) develop into primitive endoderm (PE) at the surface, while deeper cells form the epiblast. It remained unclear whether the position of cells determines their fate, such that gene expression is adjusted to cell position, or if cells are pre-specified at random positions and then sort. We have tracked and characterised dynamics of all ICM cells from the early to late blastocyst stage. Time-lapse microscopy in H2B-EGFP embryos shows that a large proportion of ICM cells change position between the surface and deeper compartments. Most of this cell movement depends on actin and is associated with cell protrusions. We also find that while most cells are precursors for only one lineage, some give rise to both, indicating that lineage segregation is not complete in the early ICM. Finally, changing the expression levels of the PE marker Gata6 reveals that it is required in surface cells but not sufficient for the re-positioning of deeper cells. We provide evidence that Wnt9A, known to be expressed in the surface ICM, facilitates re-positioning of Gata6-expressing cells. Combining these experimental results with computer modelling suggests that PE formation involves both cell sorting movements and position-dependent induction.

＝＝＝

●Blastcyst内の細胞の動きをtime-lapseでモニターし、epi-PEのsegrigationを説明する3つのモデル（Positional, Salt&Pepper, Cell sorting+positonal induction）のうち、最後のモデルに妥当性があることをコンピューターシミュレーションを用いて示す。
●Gata6+細胞はICMの表層側に来るが、この移動にはWnt9aが必要

●4/7数理ゼミで議論された論文

Dev Cell. 16:398-410, 2009

The Hippo signaling pathway components Lats and Yap pattern Tead4 activity to distinguish mouse trophectoderm from inner cell mass.

Outside cells of the preimplantation mouse embryo form the trophectoderm (TE), a process requiring the transcription factor Tead4. Here, we show that transcriptionally active Tead4 can induce Cdx2 and other trophoblast genes in parallel in embryonic stem cells. In embryos, the Tead4 coactivator protein Yap localizes to nuclei of outside cells, and modulation of Tead4 or Yap activity leads to changes in Cdx2 expression. In inside cells, Yap is phosphorylated and cytoplasmic, and this involves the Hippo signaling pathway component Lats. We propose that active Tead4 promotes TE development in outside cells, whereas Tead4 activity is suppressed in inside cells by cell contact- and Lats-mediated inhibition of nuclear Yap localization. Thus, differential signaling between inside and outside cell populations leads to changes in cell fate specification during TE formation.

＝＝＝

CDBより。
●Tead4-Cdx2 pathwayによるTE分化制御について
●Tead4の発現はpan-embryonicなのに、なぜTEでのみ機能するか？

●Cell-cell contacts→Hippo→Lats1/2---|Yorkie/Yap1→Tead4経路活性化

●活性化型Tead4として、Tead4VP16を使用（いいのか？）
●Tead4haCdx2を含むTE細胞分化にかかわる因子群を制御（Fig1～2）
●核内YapとCdx2の発現がcorrelate、かつYapでCdx2の発現が制御される（Fig.3，4)
●Wwtr1（Yap-related)がcompensativeに機能
●Yap/Wwtr1のkinaseであるLats1/2がYapのリン酸化を介して核外排出を促進
●E-cadherin阻害剤のECCD1を用いると、Yapの核外排出とリン酸化が阻害されることから、ICMのcell-cell interactionが（Hippoを介して）Yapのリン酸化+核外排出に重要（Fig6)
●胚をばらしてreaggregateしたもの/immunosurgeryでICMだけ出してcultureしたもので、cell positionによってYapの核局在が規定されていることを証明（Fig7）
●モデル（Fig7)

Immunosurgeryについての文献は。
http://www.pnas.org/content/72/12/5099.full.pdf
http://media.wiley.com/product_data/excerpt/68/04700335/0470033568.pdf

Molecular Psychiatry 15:154-165, 2010

Conditional corticotropin-releasing hormone overexpression in the mouse forebrain enhances rapid eye movement sleep

Impaired sleep and enhanced stress hormone secretion are the hallmarks of stress-related disorders, including major depression. The central neuropeptide, corticotropin-releasing hormone (CRH), is a key hormone that regulates humoral and behavioral adaptation to stress. Its prolonged hypersecretion is believed to play a key role in the development and course of depressive symptoms, and is associated with sleep impairment. To investigate the specific effects of central CRH overexpression on sleep, we used conditional mouse mutants that overexpress CRH in the entire central nervous system (CRH-COE-Nes) or only in the forebrain, including limbic structures (CRH-COE-Cam). Compared with wild-type or control mice during baseline, both homozygous CRH-COE-Nes and -Cam mice showed constantly increased rapid eye movement (REM) sleep, whereas slightly suppressed non-REM sleep was detected only in CRH-COE-Nes mice during the light period. In response to 6-h sleep deprivation, elevated levels of REM sleep also became evident in heterozygous CRH-COE-Nes and -Cam mice during recovery, which was reversed by treatment with a CRH receptor type 1 (CRHR1) antagonist in heterozygous and homozygous CRH-COE-Nes mice. The peripheral stress hormone levels were not elevated at baseline, and even after sleep deprivation they were indistinguishable across genotypes. As the stress axis was not altered, sleep changes, in particular enhanced REM sleep, occurring in these models are most likely induced by the forebrain CRH through the activation of CRHR1. CRH hypersecretion in the forebrain seems to drive REM sleep, supporting the notion that enhanced REM sleep may serve as biomarker for clinical conditions associated with enhanced CRH secretion.

＝＝＝

●Camk2a-CRE x R26-CRHの系で、BFにCRHを発現
●ストレス→corticosterone系について。しかしデータは微妙。上がるのがREMってのも・・・

Trends Cell Biol. 2010 Mar 29. [Epub ahead of print]

The Beclin 1-VPS34 complex - at the crossroads of autophagy and beyond.

An increasing body of research on autophagy provides overwhelming evidence for its connection to diverse biological functions and human diseases. Beclin 1, the first mammalian autophagy protein to be described, appears to act as a nexus point between autophagy, endosomal, and perhaps also cell death pathways. Beclin 1 performs these roles as part of a core complex that contains vacuolar sorting protein 34 (VPS34), a class III phosphatidylinositol-3 kinase. The precise mechanism of Beclin 1-mediated regulation of these cellular functions is unclear, but substantial progress has recently been made in identifying new players and their functions in Beclin 1-VSP34 complexes. Here we review emerging studies that are beginning to unveil the physiological functions of Beclin 1-VPS34 in the central control of autophagic activity and other trafficking events through the formation of distinct Beclin 1-VPS34 protein complexes.

＝＝＝

Beclin1-Vps34複合体とその周辺についてよくまとまったレビュー
UVRAGとRubiconについてがメイン。機能的役割分担がよくわかる図が有り。

noise&signal

ICT Resultsより

＝＝＝

When noise becomes the signal

European researchers have developed a new class of electronics that uses noise ? normally a problem ? as part of the signal. It means better, faster electronics.

　 ：

These are simple computing, logic gates. Their actions resemble the firing of signals as they are observed between neurons. The SUBTLE team believes that its devices can be thus used in the future to mimic neuron action in artificial networks and to serve as sensors for signals usually hidden under the noise.

   ：

＝＝＝

ノイズを利用してシグナルを増幅する試み？
神経回路との類似性について議論されている。

Cell Stem Cell, 6:323-335,2010

MicroRNA-9 Coordinates Proliferation and Migration of Human Embryonic Stem Cell-Derived Neural Progenitors

Human pluripotent stem cells offer promise for use in cell-based therapies for brain injury and diseases. However, their cellular behavior is poorly understood. Here we show that the expression of the brain-specific microRNA-9 (miR-9) is turned on in human neural progenitor cells (hNPCs) derived from human embryonic stem cells. Loss of miR-9 suppressed proliferation but promoted migration of hNPCs cultured in vitro. hNPCs without miR-9 activity also showed enhanced migration when transplanted into mouse embryonic brains or adult brains of a mouse model of stroke. These effects were not due to precocious differentiation of hNPCs. One of the key targets directly regulated by miR-9 encodes stathmin, which increases microtubule instability and whose expression in hNPCs correlates inversely with that of miR-9. Partial inhibition of stathmin activity suppressed the effects of miR-9 loss on proliferation and migration of human or embryonic rat neural progenitors. These results identify miR-9 as a novel regulator that coordinates the proliferation and migration of hNPCs.

＝＝＝

ヒトESだが、neural progenitorの発生で機能するmicro RNAの論文。
loss of miR-9でmigrationが過剰になる？