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Characterization of dpy-24(tk41) and mechanism of DPY-24 down-regulation in distal tip cell migration in Caenorhabditis elegans
No full text細胞遷移對生物的器官發育而言是一件重要的過程。線蟲的兩顆生殖腺遠端細胞的遷移過程，是研究細胞遷移的利器。遠端細胞的遷移過程有三個階段。線蟲孵出後，在第一齡末期進入第一階段，兩顆遠端細胞沿著腹部肌肉爬行。當線蟲成長到第三齡幼蟲中期時，遠端細胞轉九十度往背部行走，形成第二階段的遷移。到了第三齡幼蟲晚期，遠端細胞再度轉九十度，沿著背部肌肉往身體中央爬行，此時為第三階段。遠端細胞的遷移過程受到時間和空間上許多的因素調控。例如遠端細胞上的UNC-5細胞膜接收器和分布在腹部的UNC-6作用，控制遠端細胞往背部行走。三個調節發育時期的基因：dre-1、daf-12和lin-29，共同作用使蟲體的生殖腺在正常時期從第一階段的遷移路徑經第二階段再進入第三階段的初期。本實驗室先前分析認為DPY-24蛋白質藉由抑制unc-5的轉錄來避免第二階段爬行過早發生。在本實驗中，藉由分子遺傳技術，證實了一個新的dpy-24突變株，dpy-24(tk41)。dpy-24協同unc-5和unc-6在基因層次上調控遠端細胞在第三階段的方向選擇能力。證實了在DTC遷移過程中，unc-5和unc-6有調控第三階段方向性的能力。對於遠端細胞而言，DPY-24蛋白質只有在第一階段表現，在晚期則停止表現。本篇研究發現前述的調節發育時期的基因中，dre-1和daf-12參與了降低DPY-24晚期表現的機制。結果顯示了DPY-24受到嚴格的調控以規範進入第二階段爬行的時間點。Cell migration is critical for organogenesis during animal development. Patterned migration of gonadal distal tip cells (DTCs) in Caenorhabditis elegans is an ideal model for cell migration research. DTCs have three sequential migration phases. During phase I, DTCs migrate along the ventral body wall muscle in the L1 and L2 stages. At mid-L3, DTCs reorient and migrate dorsalward during phase II. In phase III, DTCs turn orthogonally and migrate along the dorsal body wall muscle toward midbody in the late L3 and L4 stages. Several factors have been identified and characterized that regulate DTC migration in temporally and spatially specific fashions. For example, UNC-5/Netrin receptor has been shown to act in DTCs to guide their phase II dorsal migration against the ventrally concentrated repellent of UNC-6/Netrin. Three heterochronic-related proteins, transcription factors LIN-29 and DAF-12 and F-box protein DRE-1, act redundantly to control the reflexion of the gonad in L3. Our lab has identified a zinc-finger-containing protein DPY-24 that functions to suppress the initiation of phase II migration in phase I by transcriptionally repressing unc-5. In this study, we have genetically and molecularly defined a new allele of dpy-24, tk41. In addition, we found that dpy-24 acts synergistically with unc-5 and unc-6 to regulate the phase III migration direction. This observation shows a previously unassigned function of unc-5 and unc-6 in the longitudinal DTC migration. Furthermore, DPY-24 protein is detected in phase I but not phase II or III in wild type; however, daf-12 and dre-1 double mutations block the down-regulation of DPY-24 in phase II and III. This result reveals a complex regulation of the DPY-24 level in specifying the timing of phase II migration.口試委員會審定書………………………………………………………………………i謝……………………………………………………………………………………...ii文摘要………………………………………………………………………………..iiibstract…………………………………………………………………………… ……ivntroduction……………………………………………………………………………...1aterials and Methods…………………………………………………………………14 C. elegans strains and culture methods…………………………………………...…14 Analysis of DTC migration phenotypes……………………………………………..15 Immunohistochemistry………………………………………………………………16 Image analysis……………………………………………………………………….16 Database searches and bioinformatics……………………………………………….16esults……………………………………………………………………… …………17 DTCs migration defect of dpy-24 mutants…………………………………………..17 Verification of a new dpy-24 allele…………………………………………………..18 DTCs migration defect of dpy-24;smg-2 mutants…………………………………...19 DTCs migration defect of unc-5 and unc-6 mutants………………………………...20 DTCs longitudinal migration defect of dpy-24; unc-5 and dpy-24; unc-6 mutants…20 transgene-dependent DTCs migration defect………………………………………..22 Temporal expression pattern of DPY-24 in DTCs……………………………….…..23 DRE-1 and DAF-12 act together to regulate DPY-24 expression level after phase I.25iscussion………………………………………………………………………………27 DTCs migration defect of unc-5, unc-6, and dpy-24 mutants……………………….27 DTCs longitudinal migration defect of dpy-24; unc-5 and dpy-24; unc-6 mutants…28 lag-2::gfp transgenes caused a DTC migration defect………………………………29 Temporal expression pattern of DPY-24 in DTCs…………………………………...30 The regulation of post-translation of DPY-24……………………………………….31eference……………………………………………………………………………….35 igures……………………………………………………………………… ……... …..I Figure 1. DTC migration pattern of N2 hermaphrodite……………………………….I Figure 2. The predicted protein structures of wild-type and mutant DPY-24……...…II Figure 3. DTC migration pattern of dpy-24 mutants………………………………...III Figure 4. DTC failed in phase II migration in unc-5(e53)………………………..…IV Figure 5. DPY-24 is expressed in DTC during phase I migration and diminished thereafter………………………………………………………………………………..V Figure 6. DPY-24 is diminished after phase I in dre-1(dh99)………………………VI Figure 7. DPY-24 is diminished after phase I in daf-12(rh61rh411)……………….VII Figure 8. DPY-24 is weakly expressed in DTC during phase III migration in dre-1(dh99);daf-12(rh61rh411)………………………………………………………VIII Figure 9. Percentage of ectopic DPY-24 expression in DTC during phase III migration and the ratio is normalized to phase I……………………………………...IX Figure 10. The model of the complex regulations of DPY-24 level and the dpy-24- involved-regulations of DTC migration……………………………………………….Xables………………………………………………………………………………. …XI Table 1. DTCs migration defect of dpy-24 and dpy-24;smg-2……………………...XI Table 2. The allele characterization of tk41………………………………………...XII Table 3. tk41 and tp5 belong to the same complementation group………………...XIII Table 4. DTCs migration defect of unc-5, unc-6 and unc-40……………………...XIV Table 5. DTC longitudinal migration defect of dpy-24;unc-5 mutants…………….XV Table 6. DTC longitudinal migration defect of dpy-24;unc-6 mutants………...….XVI Table 7. Transgenic-dependent DTC migration defect…………………………...XVII Table 8. dpy-24 promoter is turned on from phase I to III……………………....XVIII Table 9. 3''UTR is not sufficient for DPY-24 downregulation…………………….XIX Table 10. Coding region is sufficient for DPY-24 downregulation………………..XX Table 11. dpy-24 promoter maybe weaker in phase II and III than I………………XXIupplementary Figures……………………………………………………………....XXII Figure S1. The amino acids alignment of DPY-24 homologes………………...…XXII Figure S2. The protein structure of wild type and mutant UNC-5……………....XXIII Figure S3. The protein structure and domain function of UNC-6…………….…XXIV Figure S4. The predicted cleavage sites of DPY-24……………………………....XXV Figure S5. The predicted miRNAs which interact with dpy-24 3’UTR………....XXVIupplementary Table..……………………………………………………………. XXVII Table S1. The strains containing GFP-tagging DTCs…………………………..XXVI
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Selective Binding of Mannose-Encapsulated Gold Nanoparticles to Type 1 Pili in Escherichia coli
No full textDispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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