Mitogen-activated protein kinase (MAPK) signaling pathways are critical for the sensing and response of eukaryotic cells to extracellular changes. In Schizosaccharomyces pombe, MAPK Pmk1/ Spm1 has been involved in cell wall construction, morphogenesis, cytokinesis, and ion homeostasis, as part of the so-called cell integrity pathway together with MAPK kinase kinase Mkh1 and MAPK kinase Pek1. We show that Pmk1 is activated in multiple stress situations, including hyper-or hypotonic stress, glucose deprivation, presence of cell wall-damaging compounds, and oxidative stress induced by hydrogen peroxide or pro-oxidants. The stress-induced activation of Pmk1 was completely dependent on Mkh1 and Pek1 function, supporting a nonbranched pathway in the regulation of MAPK activation. Fluorescence microscopy revealed that Mkh1, Pek1, and Pmp1 (a protein phosphatase that inactivates Pmk1) are cytoplasmic proteins. Mkh1 and Pek1 were also found at the septum, whereas Pmk1 localized in both cytoplasm and nucleus as well as in the mitotic spindle and septum during cytokinesis. Interestingly, Pmk1 subcellular localization was unaffected by stress or the absence of Mkh1 and Pek1, suggesting that its activation by the Mkh1-Pek1 cascade takes place at the cytoplasm and/or septum and that the active and inactive forms of this kinase cross the nuclear membrane. Cdc42 GTPase and its effectors, p21-activated kinases Pak2 and Pak1, are not upstream elements controlling the basal level or the stress-induced activation of Pmk1. However, Sty1 MAPK was essential for proper Pmk1 deactivation after hypertonic stress in a process regulated by Atf1 transcription factor. These results provide the first evidence for the existence of cross-talk between two MAPK cascades during the stress response in fission yeast. Mitogen-activated protein kinase (MAPK)5 pathways are signal transduction mechanisms that regulate many cellular processes in eukaryotic organisms, from yeasts to mammals. The basic architecture of each functional cascade is composed of three sequentially acting protein kinases that become activated in response to triggering signals; the MAPK kinase kinases (MAPKKKs) phosphorylate and activate MAPK kinases (MAPKKs), which in turn phosphorylate and activate MAPKs (1, 2). Among other actions, the effector MAPKs control the activity of transcription factors either directly or indirectly. Thus, activation by specific stimuli of MAPK signal transduction pathways is accompanied by changes in gene expression that play a crucial adaptive role in the adjustment of cells to environmental conditions. In contrast to the six or more MAPK cascades present in budding yeast (3), three distinct MAPK signaling cascades have been so far identified in the fission yeast Schizosaccharomyces pombe. These include the mating pheromone-responsive MAPK pathway and the stress-activated protein kinase (SAPK) pathway, whose central elements are MAPKs Spk1 and Sty1/ Spc1, respectively (4, 5). A third pathway, known as the cell integrity pathway, consists of a MAPK ca...

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Background: Although unsaturated fatty acids such as eicosapentaenoic acid (EPA, C20:5n-3), docosahexaenoic acid (DHA, C22:6n-3) and arachidonic acid (ARA, C20:4n-6), collectively known as the highly unsaturated fatty acids (HUFA), play pivotal roles in vertebrate reproduction, very little is known about their synthesis in the ovary. The zebrafish (Danio rerio) display capability to synthesize all three HUFA via pathways involving desaturation and elongation of two precursors, the linoleic acid (LA, C18:2n-6) and linolenic acid (LNA, C18:3n-3). As a prerequisite to gain full understanding on the importance and regulation of ovarian HUFA synthesis, we described here the mRNA expression pattern of two enzymes; desaturase (fadsd6) and elongase (elovl5), involved in HUFA biosynthesis pathway, in different zebrafish ovarian follicle stages. Concurrently, the fatty acid profile of each follicle stage was also analyzed.

Purpose-The purpose of this study is to investigate student motivation and gender differences in learning Spanish as a foreign language in the Malaysian context. Method-Student motivation was measured by means of a self-report questionnaire based on Gardner's social psychological model. The questionnaire contained both close-ended and open-ended questions to provide both quantitative and qualitative information. The participants consisted of 448 students from Universiti Kuala Lumpur Malaysian Spanish Institute where Spanish is a compulsory subject. Findings-The findings showed that the students were highly motivated toward learning Spanish. No significant differences were found between integrative and instrumental motivations and gender. Nonetheless, both quantitative and qualitative results suggested that the students were slightly more instrumentally inclined but simultaneously appreciated the target language and culture. This was particularly the case for the female students who showed significantly higher instrumental motivation in Spanish learning.