200,739 research outputs found
KIF14 and citron kinase act together to promote efficient cytokinesis
No full textMultiple mitotic kinesins and microtubule-associated proteins (MAPs) act in concert to direct cytokinesis (Glotzer, M. 2005. Science. 307:1735-1739). In anaphase cells, many of these proteins associate with an antiparallel array of microtubules termed the central spindle. The MAP and microtubule-bundling protein PRC1 (protein-regulating cytokinesis 1) is one of the key molecules required for the integrity of this structure (Jiang, W., G. Jimenez, N.J. Wells, T.J. Hope, G.M. Wahl, T. Hunter, and R. Fukunaga. 1998. Mol. Cell. 2:877-885; Mollinari, C., J.P. Kleman, W. Jiang, G. Schoehn, T. Hunter, and R.L. Margolis. 2002. J. Cell Biol. 157:1175-1186). In this study, we identify an interaction between endogenous PRC1 and the previously uncharacterized kinesin KIF14 as well as other mitotic kinesins (MKlp1/CHO1, MKlp2, and KIF4) with known functions in cytokinesis (Hill, E., M. Clarke, and F.A. Barr. 2000. EMBO J. 19:5711-5719; Matuliene, J., and R. Kuriyama. 2002. Mol. Biol. Cell. 13:1832-1845; Kurasawa, Y., W.C. Earnshaw, Y. Mochizuki, N. Dohmae, and K. Todokoro. 2004. EMBO J. 23:3237-3248). We find that KIF14 targets to the central spindle via its interaction with PRC1 and has an essential function in cytokinesis. In KIF14-depleted cells, citron kinase but not other components of the central spindle and cleavage furrow fail to localize. Furthermore, the localization of KIF14 and citron kinase to the central spindle and midbody is codependent, and they form a complex depending on the activation state of citron kinase. Contrary to a previous study (Di Cunto, F., S. Imarisio, E. Hirsch, V. Broccoli, A. Bulfone, A. Migheli, C. Atzori, E. Turco, R. Triolo, G.P. Dotto, et al. 2000. Neuron. 28:115-127), we find a general requirement for citron kinase in human cell division. Together, these findings identify a novel pathway required for efficient cytokinesis
Citron Kinase Is a Cell Cycle-dependent, Nuclear Protein Required for G 2 /M Transition of Hepatocytes
No full textCitron Kinase (Citron-K) is a cell cycle-dependent protein regulating the G(2)/M transition in hepatocytes. Synchronization studies demonstrated that expression of the Citron-K protein starts at the late S and/or the early G(2) phase after that of cyclin B1. Expression of Citron-K is developmentally regulated. Levels of Citron-K mRNA and protein are highest in embryonic liver and gradually decrease after birth. Citron-K exists in interphase nuclei and begins to disperse into the cytoplasm at prophase. It concentrates at the cleavage furrow and midbody during anaphase, telophase, and cytokinesis, implicating a role in the control of cytokinesis. However, studies with knockouts show that Citron-K is not essential for cytokinesis in hepatocytes. Instead, loss of Citron-K causes a significant increase of G(2) tetraploid nuclei in one-week-old rat and mouse liver. In addition, Citron-K deficiency triggers apoptosis in a small subset of embryonic liver cells. In summary, our data demonstrate that Citron-K has a distinct cell cycle-dependent expression pattern and cellular localization as a downstream target of Rho-GTPase and functions in the control of G(2)/M transition in the hepatocyte cell cycle
The grading detection model for fingered citron slices (citrus medica ‘fingered’) based on YOLOv8-FCS
No full textIntroductionFingered citron slices possess significant nutritional value and economic advantages as herbal products that are experiencing increasing demand. The grading of fingered citron slices plays a crucial role in the marketing strategy to maximize profits. However, due to the limited adoption of standardization practices and the decentralized structure of producers and distributors, the grading process of fingered citron slices requires substantial manpower and lead to a reduction in profitability. In order to provide authoritative, rapid and accurate grading standards for the market of fingered citron slices, this paper proposes a grading detection model for fingered citron slices based on improved YOLOv8n.MethodsFirstly, we obtained the raw materials of fingered citron slices from a dealer of Sichuan fingered citron origin in Shimian County, Ya'an City, Sichuan Province, China. Subsequently, high-resolution fingered citron slices images were taken using an experimental bench, and the dataset for grading detection of fingered citron slices was formed after manual screening and labelling. Based on this dataset, we chose YOLOv8n as the base model, and then replaced the YOLOv8n backbone structure with the Fasternet main module to improve the computational efficiency in the feature extraction process. Then we redesigned the PAN-FPN structure used in the original model with BiFPN structure to make full use of the high-resolution features to extend the sensory field of the model while balancing the computation amount and model volume, and finally we get the improved target detection algorithm YOLOv8-FCS.ResultsThe findings from the experiments indicated that this approach surpassed the conventional RT-DETR, Faster R-CNN, SSD300 and YOLOv8n models in most evaluation indicators. The experimental results show that the grading accuracy of the YOLOv8-FCS model reaches 98.1%, and the model size is only 6.4 M, and the FPS is 130.3.DiscussionThe results suggest that our model offers both rapid and precise grading for fingered citron slices, holding significant practical value for promoting the advancement of automated grading systems tailored to fingered citron slices
Characterizing the subcellular localization and function of Citron Kinase in the germline of Drosophila melanogaster
No full textCytokinesis, or the final division of cells, is a conserved and highly regulated process that is crucial for all multicellular organisms. Errors in cytokinesis are linked to a variety of maladies, including microcephaly and chromosome abnormalities such as polyploidy and aneuploidy. Eukaryotes have a dynamic structure called the actin-myosin contractile ring that is responsible for separating the two daughter cells upon the completion of the final phase of mitosis. The proper positioning and timing of the contractile ring is crucial to the dividing cell. Contractile ring assembly is regulated, at least in part, by Citron Kinase, which organizes actin formation. During traditional (complete) cytokinesis, the contractile ring is the machinery responsible for the total separation of daughter cells from one another. Intriguingly, germ cells exhibit incomplete cytokinesis, in which the dividing cell never fully abscises from its daughter, which effectively tethers cells in a nest (called a cyst). The cyst is joined by intracellular canals that are stabilized by the ring canals. Cyst formation is necessary for germ cell differentiation into oocytes. Whether and how Citron Kinase controls this modified cytokinesis in these unique cells is unclear. Here, I use the model organism Drosophila melanogaster to investigate my hypothesis that Citron Kinase is required for proper cyst formation. To compare the localization of the protein in germ cells that undergo complete versus incomplete cytokinesis, I used the UAS-Gal4 system to over-express a fluorescently tagged version of Citron Kinase in the Drosophila germline. Then, to visualize the changes in germ cell division that occur in the absence of Citron Kinase, I used the UAS-Gal4 system in conjunction with RNA interference (RNAi) to knock down Citron Kinase, depleting its mRNA. My findings show that Citron Kinase is localized to the fusomes and the cytoplasm in both germline stem cells (GSCs) and dividing cysts, and to the ring canals of dividing cysts. Moreover, when Citron Kinase is lost, females exhibit a complete loss of germ cells, indicating that Citron Kinase has a larger role in female fecundity that has yet to be explored
Citron kinase is an essential effector of the Pbl-activated Rho signalling pathway in Drosophila melanogaster.
No full textCopyright © 2004 The Company of Biologists LtdPebble (Pbl)-activated RhoA signalling is essential for cytokinesis in Drosophila melanogaster. Here we report that the Drosophila citron gene encodes an essential effector kinase of Pbl-RhoA signalling in vivo. Drosophila citron is expressed in proliferating tissues but is downregulated in differentiating tissues. We find that Citron can bind RhoA and that localisation of Citron to the contractile ring is dependent on the cytokinesis-specific Pbl-RhoA signalling. Phenotypic analysis of mutants showed that citron is required for cytokinesis in every tissue examined, with mutant cells exhibiting multinucleate and hyperploid phenotypes. Strong genetic interactions were observed between citron and pbl alleles and constructs. Vertebrate studies implicate at least two Rho effector kinases, Citron and Rok, in cytokinesis. By contrast, we failed to find evidence for a role for the Drosophila ortholog of Rok in cell division. We conclude that Citron plays an essential, non-redundant role in the Rho signalling pathway during Drosophila cytokinesis.Tetyana Shandala, Stephen L. Gregory, Hazel E. Dalton, Masha Smallhorn and Robert Sain
First in the Nation in Education : Final Report,1984.
No full textThis report is one step in an ongoing process of change and is a plea for commitment for high standards in education in Iowa. Contains the final reports of the six subcommittees as adopted by the Excellence in Education Task Force, and the five recommendations made by the Task Force
Molecular cloning, expression and functional analyses of citron kinase in zebrafish embryos
No full textCitron kinase (CRIK) 屬於絲胺酸/酥胺酸磷酸激酶，並為已活化Rho的下游作用蛋白之一。若於體外培養之哺乳細胞中過度表現喪失功能之CRIK突變種會造成細胞分裂的缺陷，此結果顯示CRIK會影響細胞分裂，其於細胞分裂溝及神經組織之聚集更增加其調控細胞分裂及神經發育之可能性。在果蠅發育過程CRIK雖為各類組織細胞質分裂所必需，而CRIK基因剔除老鼠胚胎早期可發育並出生，但於出生後伴隨明顯神經細胞分裂缺陷和凋亡而死亡。CRIK基因可能在不同物種間有差異或有功能相近之同源基因存在，而導致其在不同物種之功能差異，為探討CRIK在發育過程的基因表現及其功能，我們在模式動物斑馬魚中以in silica cloning和RACE方式選殖出斑馬魚CRIK基因(zcrik)，比較分析其與其他物種CRIK蛋白質序列，利用RT-PCR偵測到成魚腦、眼睛、腎臟、胰臟、卵巢及睪丸組織中皆有zcrik的表現，在原位雜合試驗(in situ hybridization)中可見在發育24小時胚中zcrik表現多在細胞具有高度增殖的區域，如神經先驅細胞等，此現象與先前發表在老鼠表現模式相類似。為了進一步探討zcrik在斑馬魚發育的功能，我們顯微注射morpholino oligonucleotides (MO)至一胞期胚來抑制zcrik mRNA之轉譯，結果顯示zcrik-MO處理過之胚在發育六小時內死亡率較對照組高，並於早期細胞分裂時期有分裂不完整與不正常分裂情形發生，此分裂嚴重受干擾的胚亦在之後細胞遷移過程產生障礙，使得胚無法繼續正常發育而死亡，而存活之胚在受精後24小時觀察其外觀上有明顯無頭和神經管消失等缺陷發生，此結果和先前研究中指出CRIK對神經細胞分裂發育有影響相呼應，再則此等胚之缺陷與過度腹部化(ventralized)的胚型態相類似，由此推測z CRIK在胚發育時期不僅具有調節細胞分裂與神經發育的功能，對於斑馬魚的原腸胚發育過程及背腹部化亦有一定程度的影響。Citron kinase (CRIK) belongs to an evolutionarily conserved family of serine-threonine kinases and is a target molecule for activated Rho. CRIK has been suggested to be involved in regulating cytokinesis in mammalian cells due to the inhibition of cytokinesis by overexpressing dominant negative CRIK. It accumulates at the cleavage furrow and neuronal tissues that implies its roles in early development and neurogenesis. In Drosophila melanogaster, CRIK is essential for normal cell division in all tissue of Drosophila, while the knock out citron kinase allows early embryonic development, but shows defective neurogenesis in mice. To further study the role of CRIK in development, we utilized the recently developed vertebrate model, zebrafish. In this study, we first isolated the zebrafish citron kinase (zcrik) by in silica cloning and RACE experiments. Secondly, the zcrik expression patterns were examined using in situ hybridization and RT-PCR. We found that zcrik mRNA was detected by RT-PCR in adult zebrafish tissues including brain, eye, ovary, testis, kidney, spleen and gill. Whole-mount in situ hybridization of different developmental stages of zebrafish embryos revealed that zcrik expressed in the entire embryo until 18 hour post fertilization and the expression of zcrik mRNA was limit to the proliferate neuroblasts and tissues that is consistent with the expression pattern in mice. Lastly, to evaluate the functions of CRIK in zebrafish development, we applied etopic expression analysis and morpholino oligonucleotides (MO) knockdown to the developing zebrafish embryos. Functional analysis results demonstrated that gain or loss of function of zCRIK resulted defects in cytokinesis, epiboly formation and embryonic death. In addition, the MO-knockdown resulted in severe defects in CNS with little or no head structure formation, which are the characteristics of ventralized embryos at 24 hpf. These results suggest that, in addition to cytokinesis and neuronal development, citron kinase is also essential for gastrulation progressing and may be involved in dorsal-ventral patterning during development.CONTENTS
CONTENTS………………………………………………………………………Ⅰ
LIST OF TABLE……………………………………………………………………Ⅲ
LIST OF FIGURES………………………………………………………………Ⅳ
中文摘要……………………………………………………………………………1
ABSTRACT…………………………………………………………………………2
INTRODUCTION……………………………………………………………4
MATERIALS AND METHODS…………………………………………………9
Cloning of citron kinase cDNA……………………………………………………9
Blasting…………………………………………………………………………9
RNA isolation…………………………………………………………………9
Single-strand cDNA synthesis ……………………………………………10
PCR amplification……………………………………………………………11
Purification of PCR products and subcloning……………………11
Mini-preparation of plasmid DNA………………………………………12
Expression vector construction and in vitro transcription………12
Subcloning of zCRIK kinase domain fragment into T7TS expression vector12
Synthesis of mRNA of zcrik-k………………………………………………12
Antisense Morpholino design and preparation…………………………………14
Microinjection and observation…………………………………………………14
Whole mount in situ hybridization……………………………………………15
Staining of actin cytoskeleton…………………………………………………15
RESULTS…………………………………………………………………………16
Isolation of the zebrafish citron kinase homolog………………………………16
Expression of zebrafish citron kinase during development……………………18
Overexpression zebrafish citron kinase domain during development…………19
Knockdown zebrafish citron kinase by morpholino antisense oligonucleotides…19
DISCUSSION………………………………………………………………………23
REFERENCES……………………………………………………………………33
TABLE………………………………………………………………………………42
FIGURES…………………………………………………………………………4
Mathematical modeling and thermodynamic properties in the drying of citron watermelon seeds
No full textABSTRACT Citron watermelon is an agricultural product of excellent economic potential. Its seeds are widely used for oil extraction, serving as an energy source, showing nutritional characteristics that make them a suitable product to be studied. Thus, the objective was to characterize citron watermelon seeds regarding their physicochemical composition, in addition to determining drying kinetics, fitting mathematical models to the data, and determining the effective diffusivity coefficients and thermodynamic properties. The seeds were dried in a convective dryer, varying the drying temperature, with air velocity of 1.0 m s-1. With the increase in drying temperature, there were reductions in moisture content, water activity (aw), ash concentration, total titratable acidity, lipids and reducing sugar. Citron watermelon seeds are rich in lipids and ash, have low sugar concentration and low acidity; their drying kinetics was very well described by the Two Terms and Approximation of Diffusion models, followed by the models of Midilli and Page, which resulted in acceptable fits. Effective diffusivity accompanied the increase in drying temperature, and this behavior was well fitted by an Arrhenius-type equation. Enthalpy and entropy variations were reduced with drying temperature, with increments in Gibbs free energy.</div
Major Mitchell's cockatoo (Cacatua leadbeateri leadbeateri), citron-crested cockatoo (Cacatua sulphurea citrinocristata), lesser sulphur-crested cockatoo (Cacatua sulphurea sulphurea) [picture /
No full textReproduced in: Parrots of the world / Joseph M. Forshaw. Melbourne : Lansdowne, 1973, p. [120].; Also available online at: http://nla.gov.au/nla.pic-an4084446.Citron-crested cockatoo (Cacatua sulphurea citrinocristata)Lesser sulphur-crested cockatoo (Cacatua sulphurea sulphurea
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