המחברים מבקשים להודות על התמיכה מהתוכנית גלאוקומה הלאומי של הקרן האמריקאית לבריאות עוזר.

<ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> לטשטש את העכברוש בזריקה תוך הצפק של קטמין (80mg/kg) ו xylazine (8mg/kg) (יחס נפח ב 02:01). החל משחה סטרילית סיכה העין כדי למנוע התייבשות של הקרניות במהלך הניתוח. </li><li style=";text-align:right;direction:rtl"> לגלח את הראש פרווה (מן העין לרמה האוזן) ותקן ראש בראש על הבמה על ידי ראש מהדק ולהגדיר החותכות שלו בסרגל החותכת. </li><li style=";text-align:right;direction:rtl"> האזור ולחטא את הפעולה עם פתרון של 10% povidone יוד ואחריו אלכוהול 70%. </li><li style=";text-align:right;direction:rtl"> חותכים את העור ואת שרירי לחשוף את התפרים הגולגולת (sagittal, התפרים העטרה ואת רוחבי) (איור 1). החל משכך כאבים, bupivicaine ככתם לאזור החתך (שלא יעלה על 2 מ&quot;ג / ק&quot;ג). </li><li style=";text-align:right;direction:rtl"> לקדוח חור בגולגולת (O 2x2 מ&quot;מ, 0.5 מ&quot;מ משני התפרים sagittal ו רוחבי) בכל צד של תפר sagittal. הימנע קרע של קרומי המוח ואת סינוס שוכב מתחת התפרים. <img src="/files/ftp_upload/old/819_2008_6_18_3/ratSkull.png" alt="סימני ההיכר בגולגולת חולדה חיה." width="469" height="317" /> באיור 1. סימני ההיכר בגולגולת חולדה חיה. </li><li style=";text-align:right;direction:rtl"> גזור לפתוח את קרומי המוח על ידי מספריים האביב, למנוע קריעה. </li><li style=";text-align:right;direction:rtl"> לשאוב את התוכן מוחין שנמצאת מעל פני השטח הגבי של colliculus מעולה בקפידה על ידי משאבת ואקום ושלושה לבדוק נקודות ניתן לצפות: <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> את הצבע של רקמת המוח שינויים מאפור לאפור </li><li style=";text-align:right;direction:rtl"> להפסיק aspirating כאשר נוזל חסר צבע השדרה לצאת </li><li style=";text-align:right;direction:rtl"> בזהירות להגדיל את הרמה הנמוכה ביותר שאיבה אופקית לחשוף את colliculus מעולה צהבהב מכוסה על ידי דורה </li></ol></li><li style=";text-align:right;direction:rtl"> לשאוב את התוכן המוח על SC עד ארבע הקצוות של SC ניתן לצפות ישירות תחת מיקרוסקופ. החלק של קליפת המוח הסיר צריך להישמר עד למינימום כדי למנוע תופעות לוואי לא רצויות (למשל, חוסר תפקוד המנוע). היזהר שלא לגעת בסינוסים. </li><li style=";text-align:right;direction:rtl"> ספוג את הנוזל בתוך החור עם פס דק כותנה סטרילי כדי להפוך את פני השטח של SC כמו יבש ככל האפשר. ואז, במקום שכבה דקה של ספוג הג&#39;לטין מראש ספוגה זהב Fluoro 6% על פני השטח של SC (FG הוא נלקח על ידי מסופי האקסון של תאים הגנגליון ברשתית והעבירו בילטרלי retrogradely כדי somas שלה ברשתית). </li><li style=";text-align:right;direction:rtl"> ממלאים את החור עם gelfoam ולסגור את הפצע העור עם קליפים תפר. </li><li style=";text-align:right;direction:rtl"> החיות הורשו להתאושש תחת מנורת ליבון כדי להתחמם. משככי כאבים, עצירות (100mcg/kg), מוחל דרך הפה במשך 5 ימים לאחר תיוג SC במי השתייה. </li></ol>

<ol>
	<li>Ahmed, A. K. M. F., Dong, K., Sugioka, K., Yamadori, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retrograde+double+labeling+of+retinal+ganglion+cells+in+the+newborn+and+adult+albino+rat.">Retrograde double labeling of retinal ganglion cells in the newborn and adult albino rat.</a> Neurosci. Protocols. 1, 1-11 (1996).</li><li>Chan, H. C., Chang, R. C. C., Ip, A. K. C., Chiu, K., Yuen, W. H., Zee, S. Y., So, K. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroprotective+effects+of+Lycium+barbarum+Lynn+on+protecting+retinal+ganglion+cells+in+an+ocular+hypertension+model+of+glaucoma.">Neuroprotective effects of Lycium barbarum Lynn on protecting retinal ganglion cells in an ocular hypertension model of glaucoma.</a> Experimental Neurology. 203, 269-273 (2007).</li><li>Forrester, J., Peters, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nerve+fibers+in+the+optic+nerve+of+rat.">Nerve fibers in the optic nerve of rat.</a> Nature. 214, 245-247 (1967).</li><li>Ji, J. Z., Elyaman, W., Yip, H. K., Lee, V. W. H., Yick, L. W., Hugon, J., So, K. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CNTF+promotes+survival+of+retinal+ganglion+cells+after+induction+of+ocular+hypertension+in+rats:+the+possible+involvement+of+STAT3+pathway.">CNTF promotes survival of retinal ganglion cells after induction of ocular hypertension in rats: the possible involvement of STAT3 pathway.</a> European Journal of Neuroscience. 19, 265-272 (2004).</li><li>Li, R. S., Chen, B. Y., Tay, D. K., Chan, H. H. L., Pu, M. L., So, K. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Melanopsin-Expressing+Retinal+Ganglion+Cells+Are+More+Injury-Resistant+in+a+Chronic+Ocular+Hypertension+Model.+Investigative.">Melanopsin-Expressing Retinal Ganglion Cells Are More Injury-Resistant in a Chronic Ocular Hypertension Model. Investigative.</a> Ophthalmology &amp; Visual Science. 47, 2951-2958 (2006).</li></ol>

<ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> למה להשתמש בשיטה כירורגית עבור לספור הגנגליון ברשתית התא? ב עכברוש על 98% מכלל התאים הגנגליון ברשתית (RGC) ידועים הפרויקט colliculus מעולה הנגדי (SC). יישום fluoro זהב על פני השטח של SC יכול תווית כמעט כל RGCs, כך אנחנו יכולים להתמקד נוירון זה ברשתית הפגיעים ביותר גלאוקומה. השווה עם תיוג מדרדר של RGC ידי הצבת FG בגדם של עצב הראייה transected עבור 2 ימים, התערבות של הישרדות RGC ממוזער. השווה עם כתמים סגולים cresyl כי כתמי התא amacrine, RGC ותא endothelia של כלי הדם שכבת הגנגליון ברשתית התא, שיטה זו היא ספציפית יותר RGC. </li><li style=";text-align:right;direction:rtl"> כיצד למנוע דימום מוגזם? ראשית, ודא עכברוש הוא מורדם כראוי על ידי בדיקת טונוס שרירים ואת רפלקס הקרנית. הרדמה מספקת יגרום לדימום רב. שנית, למנוע פעולות שיפגעו הסינוס כגון קידוח קרוב מדי תפר או קריעה של קרומי המוח לתוך הקיר בסינוסים. שלישית, להיות זהיר כדי לשמור על הדורה שוכב על שטחי שלם SC במיוחד באזור האף. </li><li style=";text-align:right;direction:rtl"> כמה זמן לוקח עד RGCs מסומנים? ארבעה ימים לאחר תיוג SC, RGC יכול להיות מתויג. אני בדרך כלל להמתין שבעה ימים לקבלת תוצאות טובות יותר. </li></ol>

retrograde labeling of retinal ganglion cells by application of fluoro-gold on the surface of superior colliculus

גנגליון רשתית תא (RGC) ספירת חיונית כדי להעריך את ניוון הרשתית במיוחד גלאוקומה. אמין תיוג RGC חיונית להערכת ההשפעות של טיפול כלשהו. בשנת החולדה, על 98% RGCs ידוע הפרויקט colliculus מעולה הנגדי (SC) (פורסטר פיטרס, 1967). יישום fluoro זהב (FG) על פני השטח של SC יכול תווית כמעט כל RGCs, כך שנוכל להתמקד נוירון זה ברשתית הפגיעים ביותר גלאוקומה. FG הוא נלקח על ידי מסופי האקסון של תאים הגנגליון ברשתית והעבירו בילטרלי retrogradely כדי somas שלה ברשתית. השווה עם תיוג מדרדר של RGC ידי הצבת FG בגדם של עצב הראייה transected עבור 2 ימים, התערבות של הישרדות RGC ממוזער. השווה עם כתמים סגולים cresyl כי כתמי RGCs, תאים amacrine ו האנדותל של כלי הדם שכבת הגנגליון ברשתית התא, בשיטה זו תיוג הוא ספציפי יותר RGC. וידאו זה מתאר את שיטת תיוג מדרדר של RGC ידי יישום FG על פני השטח של SC. ניתוחים כוללים קידוח בגולגולת; aspirating קליפת לחשוף את SC ויישום ספוג ג&#39;לטין על פני כל הגב של SC מוצגים. עצות שימושיות למניעת דימום תוך גולגולתי השאיפה מסיבי של SC קיבלו.

Watch this Scientific Journal Video about Retrograde Labeling of Retinal Ganglion Cells by Application of Fluoro-Gold on the Surface of Superior Colliculus at JoVE.com

Retrograde Labeling of Retinal Ganglion Cells by Application of Fluoro-Gold on the Surface of Superior Colliculus

וידאו זה מתאר את שיטת תיוג מדרדר של RGC ידי יישום fluoro זהב (FG) על פני השטח של מעולה colliculus (SC). טכניקה מערבת קידוח בגולגולת, aspirating קליפת המוח, וליישם ספוג ג&#39;לטין על פני כל הגב של SC.

תיוג מדרדר לתאי הגנגליון של הרשתית על ידי יישום של זהב Fluoro על פני השטח של Colliculus מעולה

Retinal ganglion cell (RGC) counting is essential to evaluate retinal degeneration especially in glaucoma. Reliable RGC labeling is fundamental for ...

retrograde-labeling-retinal-ganglion-cells-application-fluoro-gold-on

Universidad San Sebastian

Research

JoVE Journal

Biology

15.3K Views.  The University of Hong Kong - HKU. וידאו זה מתאר את שיטת תיוג מדרדר של RGC ידי יישום fluoro זהב (FG) על פני השטח של מעולה colliculus (SC). טכניקה מערבת קידוח בגולגולת, aspirating קליפת המוח, וליישם ספוג ג'לטין על פני כל הגב של SC.

Video: Retrograde Labeling of Retinal Ganglion Cells by Application of Fluoro-Gold on the Surface of Superior Colliculus

In utero and ex vivo Electroporation for Gene Expression in Mouse Retinal Ganglion Cells

The retina and its sole output neuron, the retinal ganglion cell (RGC), comprise an excellent model in which to examine biological questions such as cell differentiation, axon guidance, retinotopic organization and synapse formation[1]. One drawback is the inability to efficiently and reliably manipulate gene expression in RGCs in vivo, especially in the otherwise accessible murine visual pathways. Transgenic mice can be used to manipulate gene expression, but this approach is often expensive, time consuming, and can produce unwanted side effects. In chick, in ovo electroporation is used to manipulate gene expression in RGCs for examining retina and RGC development. Although similar electroporation techniques have been developed in neonatal mouse pups[2], adult rats[3], and embryonic murine retinae in vitro[4], none of these strategies allow full characterization of RGC development and axon projections in vivo. To this end, we have developed two applications of electroporation, one in utero and the other ex vivo, to specifically target embryonic murine RGCs[5, 6]. 
With in utero retinal electroporation, we can misexpress or downregulate specific genes in RGCs and follow their axon projections through the visual pathways in vivo, allowing examination of guidance decisions at intermediate targets, such as the optic chiasm, or at target regions, such as the lateral geniculate nucleus. Perturbing gene expression in a subset of RGCs in an otherwise wild-type background facilitates an understanding of gene function throughout the retinal pathway. Additionally, we have developed a companion technique for analyzing RGC axon growth in vitro. We electroporate embryonic heads ex vivo, collect and incubate the whole retina, then prepare explants from these retinae several days later. Retinal explants can be used in a variety of in vitro assays in order to examine the response of electroporated RGC axons to guidance cues or other factors. In sum, this set of techniques enhances our ability to misexpress or downregulate genes in RGCs and should greatly aid studies examining RGC development and axon projections.

In utero and ex vivo Electroporation for Gene Expression in Mouse Retinal Ganglion Cells

Here we present two techniques for manipulating gene expression in murine retinal ganglion cells (RGCs) by in utero and ex vivo electroporation. These techniques enable one to examine how alterations in gene expression affect RGC development, axon guidance, and functional properties.

ב electroporation ברחם לשעבר vivo על ביטוי גנים בתאים עכבר גנגליון רשתית

The retina and its sole output neuron, the retinal ganglion cell (RGC), comprise an excellent model in which to examine biological questions such as cell ...

Fluorescent Labeling of Drosophila Heart Structures

The Drosophila melanogaster dorsal vessel, or heart, is a tubular structure comprised of a single layer of contractile cardiomyocytes, pericardial cells that align along each side of the heart wall, supportive alary muscles and, in adults, a layer of ventral longitudinal muscle cells. The contractile fibers house conserved constituents of the muscle cytoarchitecture including densely packed bundles of myofibrils and cytoskeletal/submembranous protein complexes, which interact with homologous components of the extracellular matrix. Here we describe a protocol for the fixation and the fluorescent labeling of particular myocardial elements from the hearts of dissected larvae and semi-intact adult Drosophila. Specifically, we demonstrate the labeling of sarcomeric F-actin and of &alpha;-actinin in larval hearts. Additionally, we perform labeling of F-actin and &alpha;-actinin in myosin-GFP expressing adult flies and of &alpha;-actinin and pericardin, a type IV extracellular matrix collagen, in wild type adult hearts. Particular attention is given to a mounting strategy for semi-intact adult hearts that minimizes handling and optimizes the opportunity for maintaining the integrity of the cardiac tubes and the associated tissues. These preparations are suitable for imaging via fluorescent and confocal microscopy. Overall, this procedure allows for careful and detailed analysis of the structural characteristics of the heart from a powerful genetically tractable model system.

Fluorescent Labeling of Drosophila Heart Structures

Here we describe a basic protocol for fluorescent labeling of different elements of heart tubes from larva and adult Drosophila melanogaster. These specimens are well-suited for imaging via fluorescent or confocal microscopy. This technique permits detailed structural analysis of the features of the hearts from a powerful model organism.

תיוג של פלורסנט תסיסנית לב מבנים

The Drosophila melanogaster dorsal vessel, or heart, is a tubular structure comprised of a single layer of contractile cardiomyocytes, pericardial cells ...

Isolation of Retinal Stem Cells from the Mouse Eye

The adult mouse retinal stem cell (RSC) is a rare quiescent cell found within the ciliary epithelium (CE) of the mammalian eye1,2,3. The CE is made up of non-pigmented inner and pigmented outer cell layers, and the clonal RSC colonies that arise from a single pigmented cell from the CE are made up of both pigmented and non-pigmented cells which can be differentiated to form all the cell types of the neural retina and the RPE. There is some controversy about whether all the cells within the spheres all contain at least some pigment4; however the cells are still capable of forming the different cell types found within the neural retina1-3. In some species, such as amphibians and fish, their eyes are capable of regeneration after injury5, however; the mammalian eye shows no such regenerative properties. We seek to identify the stem cell in vivo and to understand the mechanisms that keep the mammalian retinal stem cells quiescent6-8, even after injury as well as using them as a potential source of cells to help repair physical or genetic models of eye injury through transplantation9-12. Here we describe how to isolate the ciliary epithelial cells from the mouse eye and grow them in culture in order to form the clonal retinal stem cell spheres. Since there are no known markers of the stem cell in vivo, these spheres are the only known way to prospectively identify the stem cell population within the ciliary epithelium of the eye.

In this video, we will demonstrate how to isolate retinal stem cells from the ciliary epithelium of the mouse eye and grow them in culture to form clonal retinal spheres. The spheres that are isolated possess the cardinal properties of stem cells: self-renewal and multipotentiality.

בידוד של גזע תאים רשתית העין של העכבר

The adult mouse retinal stem cell (RSC) is a rare quiescent cell found within the ciliary epithelium (CE) of the mammalian eye1,2,3. The CE is made up of ...

Analyzing the Function of Small GTPases by Microinjection of Plasmids into Polarized Epithelial Cells

Epithelial cells polarize their plasma membrane into biochemically and functionally distinct apical and basolateral domains where the apical domain faces the 'free' surfaces and the basolateral membrane is in contact with the substrate and neighboring cells. Both membrane domains are separated by tight junctions, which form a diffusion barrier. Apical-basolateral polarization can be recapitulated successfully in culture when epithelial cells such as Madin-Darby Canine Kidney (MDCK) cells are seeded at high density on polycarbonate filters and cultured for several days 1 2. Establishment and maintenance of cell polarity is regulated by an array of small GTPases of the Ras superfamily such as RalA, Cdc42, Rab8, Rab10 and Rab13 3 4 5 6 7. Like all GTPases these proteins cycle between an inactive GDP-bound state and an active GTP-bound state. Specific mutations in the nucleotide binding regions interfere with this cycling 8. For example, Rab13T22N is permanently locked in the GDP-form and thus dubbed 'dominant negative', whereas Rab13Q67L can no longer hydrolyze GTP and is thus locked in a 'dominant active' state 7. To analyze their function in cells both dominant negative and dominant active alleles of GTPases are typically expressed at high levels to interfere with the function of the endogenous proteins 9. An elegant way to achieve high levels of overexpression in a short amount of time is to introduce the plasmids encoding the relevant proteins directly into the nuclei of polarized cells grown on filter supports using microinjection technique. This is often combined with the co-injection of reporter plasmids that encode plasma membrane receptors that are specifically sorted to the apical or basolateral domain. A cargo frequently used to analyze cargo sorting to the basolateral domain is a temperature sensitive allele of the vesicular stomatitis virus glycoprotein (VSVGts045) 10. This protein cannot fold properly at 39&deg;C and will thus be retained in the endoplasmic reticulum (ER) while the regulatory protein of interest is assembled in the cytosol. A shift to 31&deg;C will then allow VSVGts045 to fold properly, leave the ER and travel to the plasma membrane 11. This chase is typically performed in the presence of cycloheximide to prevent further protein synthesis leading to cleaner results. Here we describe in detail the procedure of microinjecting plasmids into polarized cells and subsequent incubations including temperature shifts that allow a comprehensive analysis of regulatory proteins involved in basolateral sorting.

This article details the procedures involved in overexpression and analysis of small GTPases in polarized epithelial cells using microinjection technique.

ניתוח פונקציה של GTPases קטנים על ידי Microinjection של פלסמידים לתוך תאים אפיתל מקוטב

Epithelial cells polarize their plasma membrane into biochemically and functionally distinct apical and basolateral domains where the apical domain faces ...

Visualization of Mitochondrial Respiratory Function using Cytochrome C Oxidase / Succinate Dehydrogenase (COX/SDH) Double-labeling Histochemistry

Mitochondrial DNA (mtDNA) defects are an important cause of disease and may underlie aging and aging-related alterations 1,2. The mitochondrial theory of aging suggests a role for mtDNA mutations, which can alter bioenergetics homeostasis and cellular function, in the aging process 3. A wealth of evidence has been compiled in support of this theory 1,4, an example being the mtDNA mutator mouse 5; however, the precise role of mtDNA damage in aging is not entirely understood 6,7.
Observing the activity of respiratory enzymes is a straightforward approach for investigating mitochondrial dysfunction. Complex IV, or cytochrome c oxidase (COX), is essential for mitochondrial function. The catalytic subunits of COX are encoded by mtDNA and are essential for assembly of the complex (Figure 1). Thus, proper synthesis and function are largely based on mtDNA integrity 2. Although other respiratory complexes could be investigated, Complexes IV and II are the most amenable to histochemical examination 8,9. Complex II, or succinate dehydrogenase (SDH), is entirely encoded by nuclear DNA (Figure 1), and its activity is typically not affected by impaired mtDNA, although an increase might indicate mitochondrial biogenesis 10-12. The impaired mtDNA observed in mitochondrial diseases, aging, and age-related diseases often leads to the presence of cells with low or absent COX activity 2,12-14. Although COX and SDH activities can be investigated individually, the sequential double-labeling method 15,16 has proved to be advantageous in locating cells with mitochondrial dysfunction 12,17-21.
Many of the optimal constitutions of the assay have been determined, such as substrate concentration, electron acceptors/donors, intermediate electron carriers, influence of pH, and reaction time 9,22,23. 3,3'-diaminobenzidine (DAB) is an effective and reliable electron donor 22. In cells with functioning COX, the brown indamine polymer product will localize in mitochondrial cristae and saturate cells 22. Those cells with dysfunctional COX will therefore not be saturated by the DAB product, allowing for the visualization of SDH activity by reduction of nitroblue tetrazolium (NBT), an electron acceptor, to a blue formazan end product 9,24. Cytochrome c and sodium succinate substrates are added to normalize endogenous levels between control and diseased/mutant tissues 9. Catalase is added as a precaution to avoid possible contaminating reactions from peroxidase activity 9,22. Phenazine methosulfate (PMS), an intermediate electron carrier, is used in conjunction with sodium azide, a respiratory chain inhibitor, to increase the formation of the final reaction products 9,25. Despite this information, some critical details affecting the result of this seemly straightforward assay, in addition to specificity controls and advances in the technique, have not yet been presented.

Visualization of Mitochondrial Respiratory Function using Cytochrome C Oxidase / Succinate Dehydrogenase COX/SDH Double-labeling Histochemistry

The cytochrome c oxidase/sodium dehydrogenase (COX/SDH) double-labeling method allows for direct visualization of mitochondrial respiratory enzyme deficiencies in fresh-frozen tissue sections. This is a straightforward histochemical technique and is useful in investigating mitochondrial diseases, aging, and aging-related disorders.

ויזואליזציה של תפקודי נשימה מיטוכונדריאלי באמצעות ציטוכרום C מונואמין / succinate dehydrogenase (COX / SDH) תיוג פעמיים Histochemistry

Mitochondrial DNA (mtDNA) defects are an important cause of disease and may underlie aging and aging-related alterations 1,2. The mitochondrial theory of ...

Avidity-based Extracellular Interaction Screening (AVEXIS) for the Scalable Detection of Low-affinity Extracellular Receptor-Ligand Interactions

Extracellular protein:protein interactions between secreted or membrane-tethered proteins are critical for both initiating intercellular communication and ensuring cohesion within multicellular organisms. Proteins predicted to form extracellular interactions are encoded by approximately a quarter of human genes1, but despite their importance and abundance, the majority of these proteins have no documented binding partner. Primarily, this is due to their biochemical intractability: membrane-embedded proteins are difficult to solubilise in their native conformation and contain structurally-important posttranslational modifications. Also, the interaction affinities between receptor proteins are often characterised by extremely low interaction strengths (half-lives &lt; 1 second) precluding their detection with many commonly-used high throughput methods2. 
Here, we describe an assay, AVEXIS (AVidity-based EXtracellular Interaction Screen) that overcomes these technical challenges enabling the detection of very weak protein interactions (t1/2 &le; 0.1 sec) with a low false positive rate3. The assay is usually implemented in a high throughput format to enable the systematic screening of many thousands of interactions in a convenient microtitre plate format (Fig. 1). It relies on the production of soluble recombinant protein libraries that contain the ectodomain fragments of cell surface receptors or secreted proteins within which to screen for interactions; therefore, this approach is suitable for type I, type II, GPI-linked cell surface receptors and secreted proteins but not for multipass membrane proteins such as ion channels or transporters.
The recombinant protein libraries are produced using a convenient and high-level mammalian expression system4, to ensure that important posttranslational modifications such as glycosylation and disulphide bonds are added. Expressed recombinant proteins are secreted into the medium and produced in two forms: a biotinylated bait which can be captured on a streptavidin-coated solid phase suitable for screening, and a pentamerised enzyme-tagged (&beta;-lactamase) prey. The bait and prey proteins are presented to each other in a binary fashion to detect direct interactions between them, similar to a conventional ELISA (Fig. 1). The pentamerisation of the proteins in the prey is achieved through a peptide sequence from the cartilage oligomeric matrix protein (COMP) and increases the local concentration of the ectodomains thereby providing significant avidity gains to enable even very transient interactions to be detected. By normalising the activities of both the bait and prey to predetermined levels prior to screening, we have shown that interactions having monomeric half-lives of 0.1 sec can be detected with low false positive rates3.

Avidity-based Extracellular Interaction Screening AVEXIS for the Scalable Detection of Low-affinity Extracellular Receptor-Ligand Interactions

AVEXIS is a high throughput protein interaction assay developed to systematically screen for novel extracellular receptor-ligand pairs involved in cellular recognition processes. It is specifically designed to detect transient protein interactions that are difficult to identify using other high throughput approaches.

הלהיטות מבוסס אינטראקציה הקרנת תאיים (AVEXIS) לאיתור Scalable זיקה נמוכה קולטן ליגנד אינטראקציות תאיים

Extracellular protein:protein interactions between secreted or membrane-tethered proteins are critical for both initiating intercellular communication and ...

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) maintain the turnover of all mature blood cell lineages. The coordination of the complex signals leading to specific HSC fates relies upon the interaction between HSCs and the intricate bone marrow microenvironment, which is still poorly understood[1-2].
We describe how by combining a newly developed specimen holder for stable animal positioning with multi-step confocal and two-photon in vivo imaging techniques, it is possible to obtain high-resolution 3D stacks containing HSPCs and their surrounding niches and to monitor them over time through multi-point time-lapse imaging. High definition imaging allows detecting ex vivo labeled hematopoietic stem and progenitor cells (HSPCs) residing within the bone marrow. Moreover, multi-point time-lapse 3D imaging, obtained with faster acquisition settings, provides accurate information about HSPC movement and the reciprocal interactions between HSPCs and stroma cells.
Tracking of HSPCs in relation to GFP positive osteoblastic cells is shown as an exemplary application of this method. This technique can be utilized to track any appropriately labeled hematopoietic or stromal cell of interest within the mouse calvarium bone marrow space.

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

The nature of the interactions between hematopoietic stem and progenitor cells (HSPCs) and bone marrow niches is poorly understood. Custom hardware modifications and a multi-step acquisition protocol allow the use of two-photon and confocal microscopy to image ex vivo labeled HSPCs homed within bone marrow areas, tracking interactions and movement.

במעקב 4 ממדי Vivo של תאי גזע ואבות היווצרות דם במבוגרי עכבר calvarial מח עצם

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) ...

A Standardized Method for the Analysis of Liver Sinusoidal Endothelial Cells and Their Fenestrations by Scanning Electron Microscopy

Liver sinusoidal endothelial cells are the gateway to the liver, their transcellular fenestrations allow the unimpeded transfer of small and dissolved substances from the blood into the liver parenchyma for metabolism and processing. Fenestrations are dynamic structures - both their size and/or number can be altered in response to various physiological states, drugs, and disease, making them an important target for modulation. An understanding of how LSEC morphology is influenced by various disease, toxic, and physiological states and how these changes impact on liver function requires accurate measurement of the size and number of fenestrations. In this paper, we describe scanning electron microscopy fixation and processing techniques used in our laboratory to ensure reproducible specimen preparation and accurate interpretation. The methods include perfusion fixation, secondary fixation and dehydration, preparation for the scanning electron microscope and analysis. Finally, we provide a step by step method for standardized image analysis which will benefit all researchers in the field.

The fenestrated liver sinusoidal endothelial cell is a biologically important filter system that is highly influenced by various diseases, toxins, and physiological states. These changes significantly impact on liver function. We describe methods for the standardisation of the measurement of the size and number of fenestrations in these cells.

סטנדרטי שיטה לניתוח של תאי הכבד סינוסי האנדותל וFenestrations על ידי סריקה מיקרוסקופית אלקטרונים

Liver sinusoidal endothelial cells are the gateway to the liver, their transcellular fenestrations allow the unimpeded transfer of small and dissolved ...

Isolation of Specific Genomic Regions and Identification of Associated Molecules by enChIP

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the functions of these regions. To enable the non-biased identification of molecules interacting with a specific genomic region of interest, we recently developed the engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) technique. Here, we describe how to use enChIP to isolate specific genomic regions and identify the associated proteins and RNAs. First, a genomic region of interest is tagged with a transcription activator-like (TAL) protein or a clustered regularly interspaced short palindromic repeats (CRISPR) complex consisting of a catalytically inactive form of Cas9 and a guide RNA. Subsequently, the chromatin is crosslinked and fragmented by sonication. The tagged locus is then immunoprecipitated and the crosslinking is reversed. Finally, the proteins or RNAs that are associated with the isolated chromatin are subjected to mass spectrometric or RNA sequencing analyses, respectively. This approach allows the successful identification of proteins and RNAs associated with a genomic region of interest.

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the functions of these regions. This protocol describes procedures to perform engineered DNA-binding molecule-mediated chromatin imunoprecipitation (enChIP) for identification of proteins and RNAs associated with a specific genomic region.

בידוד של אזורים הגנומי ספציפיים וזיהוי של Associated מולקולות על ידי enChIP

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the ...

Light Sheet Fluorescence Microscopy of Plant Roots Growing on the Surface of a Gel

One of the key questions in understanding plant development is how single cells behave in a larger context of the tissue. Therefore, it requires the observation of the whole organ with a high spatial- as well as temporal resolution over prolonged periods of time, which may cause photo-toxic effects. This protocol shows a plant sample preparation method for light-sheet microscopy, which is characterized by mounting the plant vertically on the surface of a gel. The plant is mounted in such a way that the roots are submerged in a liquid medium while the leaves remain in the air. In order to ensure photosynthetic activity of the plant, a custom-made lighting system illuminates the leaves. To keep the roots in darkness the water surface is covered with sheets of black plastic foil. This method allows long-term imaging of plant organ development in standardized conditions.

This protocol shows a plant sample preparation method for light-sheet microscopy. The setup is characterized by mounting the plant vertically on the surface of a gel and letting it grow in controlled bright conditions. This allows long-term observation of plant organ development in standardized conditions.

מיקרוסקופ פלואורסצנטי גיליון אור של שורשי הצמח גדל על פני השטח של ג&#39;ל

One of the key questions in understanding plant development is how single cells behave in a larger context of the tissue. Therefore, it requires the ...