Soybean (Glycine max) and rice (Oryza sativa) are the most important crops cultivated worldwide. The productivity of both crops is severely limited due to drought stresses. Abscisic acid (ABA) signaling is one of the crucial phytohormones which acts as the signaling mediator in different environmental stress for adaptive response of plants. In this study, functional characterization of abscisic acid-activated protein kinase-like kinase 1 (AALK1), and low molecular weight protein tyrosine phosphatase (LMWPTP) were studied by developing gain-ofunction and loss-ofunction phenotypes by transgenesis. Physiological response of AALK1 showed that AALK1 modulates the drought stress response ins soybean plants. The study has demonstrated several key genes are differentially expressed control, and aalk1-RNAi silenced lines under drought treatment. The AALK1 overexpression lines enhanced the transcription of other ABA-responsive genes, indicating that the AALK1 is a positive regulator of ABA-mediated stress signaling pathways in soybean. The phylogenetic analysis and domain analysis also supports that AALK1 is abscisic acid-activated protein kinase and has a role in drought response. Phenotype analysis of LMWPTP in rice showed that transgenic overexpression of LMW-PTP exhibited significantly improved drought tolerance in comparison to RNAi silencing and control plants ,which indicates that LMWPTP modulates the drought stress tolerance of rice plants. Further, 5 putative tyrosine phosphorylated proteins were detected through immunoblotting and identified by mass spectrometry. Some of these tyrosine phosphorylated proteins are likely to be target proteins of LMWPTP. Together, the present findings strengthen the knowledge about the functional role of AALK1 and LMWPTP, which can be utilized as a promising gene-based molecular marker in transgenic breeding for generating crop plants with improved drought tolerance which ultimately improve the grain yields.

The purpose of this work was to determine the manner of inheritance of serum alkaline phosphatase in the racing pigeon, (Columba livia). The evidence indicates that the electrophoretic patterns of serum alkaline phosphatase in the pigeon are inherited as codominant genes.

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Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Virginia, 2000. / Spine title: Synaptic role of TYR-phosphatases. Includes bibliographical references (p. 135-172). Also available online through Digital Dissertations.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains vii, 79 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 68-79).

Thesis (Ph. D.)--Illinois State University, 2006. / Title from title page screen, viewed on June 8, 2007. Dissertation Committee: Kevin A. Edwards (chair), Craig Gatto, Wade A. Nichols, Samuel Galewsky, John C. Sedbrook. Includes bibliographical references (leaves 218-245) and abstract. Also available in print.

Chez la drolosophile, des mutants de Greatwall présentent des défauts de condensation des chromosomes lors de la mitose. Plus tard, la même équipe a montré que chez le Xénope, Greatwall est nécessaire pour entrer en mitose. L'idée consistant à penser que puisque Greatwall ne permet plus l'entrée en mitose, il joue un rôle dans la boucle qui conduit à l'auto-amplification de MPF. En 2009, notre équipe a montré que Greatwall est réellement impliquée dans l'entrée en mitose, mais de façon indirecte par rapport à la boucle d'amplification de MPF, et cela en contrôlant l'activité de la phosphatase PP2A. Notre équipe a montré que lorsque l'on enlève PP2A, on peut sauver le phénotype de l'absence de Greatwall. Plus tard, il a été montré que la phosphorylation de Greatwall est nécessaire pour l'entrée en mitose. La phosphorylation de Greatwall sur la partie C-terminale est nécessaire pour activer Greatwall. Par conséquent, Greatwall doit être phosphorylé pour être actif. Une fois activé, Greatwall est capable de phosphoryler Arpp19 qui lie la phosphatase PP2AB55, et qui l'inhibe permettant ainsi de maintenir les phosphorylations des substrats mitotiques. Si cette voie de signalisation n'est pas fonctionnelle, la phosphatase PP2A va déphosphoryler tous les substrats mitotiques et la cellule n'entrera jamais en mitose. Greatwall doit être phosphorylé pour s'activer et pour entrer en mitose, mais on observe aussi qu'au moment de la sortie de mitose, il est déphosphorylé, et il doit être déphosphorylé pour s'inactiver. (On ne sait pas s'il est requisse pour sortir). Mon projet consiste à chercher la/les phosphatase(s) qui pourrait contrôler l'activité ou l'inactivation de Greatwall. Les questions que l'on se pose : Comment et par quelle(s) phosphatase(s) Greatwall est déphosphorylé, comment ces phosphoatases sont activées, quel est l'ordre d'activation de ces phosphatases ? Pour étudier comment Greatwall est déphosphorylé, il y a 2 sites majors : T194 et S875. Ces 2 sites sont nécessaires pour l'activité de Greatwall. Nous avons réalisé les 2 mutants T194A et S875A, et les traduit dans l'extrait interphasique d'œufs de Xénope, pour mesurer l'activité de kinase Greatwall. Pour déphosphoryler ces 2 sites, il y a 4 phosphatases principales comme candidats : Calcineurine, Fcp1, PP1, PP2A. / The establishment of mitosis requires phosphorylaton of several substrates induced by kinases. Cdk1-cyclin B and Greatwall kinases are both necessary for the entry into mitosis. Cdk1-cyclin B complex phosphorylates many substrates and at the same time Greatwall phosphorylates Arpp19 which binds PP2AB55 phosphatase and inhibits it. PP2AB55 has an important role in the dephosphorylation of Cdk1-cyclin B mitotic substrates.In my laboratory, we found that after Greatwall depletion, either in Xenopus egg extracts or in human cells, PP2A is no longer inhibited and cells exit mitosis. Since activation of Greatwall requires its phosphorylation in the c-terminal part and in the T-loop site, we suppose that mitosis exit require dephosphorylation of Greatwall. So these dephosphorylations could be involved for Greatwall inactivation. Several phosphatases are candidates for this process: Fcp1, PP1, PP2A and Calcineurin. My project proposes to determine the involvement of these four phosphatases in Xenopus egg extracts after depletion and overexpression of these four proteins.

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