Multipath mitigation technique under strong multipath environment using multiple antennas

2016-2017 > Academic research: refereed > Publication in refereed journal201804_a bcmaVersion of RecordPublishe

Activation of extracellular signal-regulated kinases during dehydration in the African clawed frog, Xenopus laevis

In its native environment the African clawed frog, Xenopus laevis, can experience seasonally arid conditions that impose dehydration stress. Activation of intracellular signal transduction cascades can mediate and coordinate biochemical responses to ameliorate dehydration stress. This study examines the extracellular signal-regulated kinase (ERK) signaling cascade, analyzing responses of both upstream and downstream components in six tissues of X. laevis experiencing medium and high levels of dehydration, 16.6±1.59 and 28.0±1.6% of total body water lost, respectively. Immunoblotting was used to assess the three tiers in this mitogen-activated protein kinase (MAPK) cascade: the initiating MAPK kinase kinases (c-Raf. MEKK), the MAPK kinase (MEK1/2), and finally the MAPK (ERK1/2). The amount of active phosphorylated c-Raf Ser338 rose by 2- to 2.5-fold under high dehydration in muscle, lung and skin whereas MEKK protein levels rose in these organs and also increased 4-fold in liver. As a result, phosphorylated active MEK1/2 Ser217/221 increased significantly by 2- to 6-fold during dehydration which, in turn, led to 2- to 6-fold increases in phospho-ERK Thr202/Tyr204 content In all tissues except skin. Given this clear demonstration of ERK cascade activation, two downstream targets of ERK2 were then evaluated. The amount of phosphorylated active transcription factor, STAT3 Ser727 and p90 ribosomal S6 kinase (RSK Ser380) increased particularly in muscle, lung and kidney. Furthermore, RSK activation was correlated with a 5- to 8-fold increase in phosphorylation of its target, S6 ribosomal protein. Overall, the results show a strong conserved activation of the ERK cascade in X. laevis tissues in response to dehydration

Ragulator and GATOR1 complexes promote fission yeast growth by attenuating TOR complex 1 through Rag GTPases.

TOR complex 1 (TORC1) is an evolutionarily conserved protein kinase complex that promotes cellular macromolecular synthesis and suppresses autophagy. Amino-acid-induced activation of mammalian TORC1 is initiated by its recruitment to the RagA/B-RagC/D GTPase heterodimer, which is anchored to lysosomal membranes through the Ragulator complex. We have identified in the model organism Schizosaccharomyces pombe a Ragulator-like complex that tethers the Gtr1-Gtr2 Rag heterodimer to the membranes of vacuoles, the lysosome equivalent in yeasts. Unexpectedly, the Ragulator-Rag complex is not required for the vacuolar targeting of TORC1, but the complex plays a crucial role in attenuating TORC1 activity independently of the Tsc1-Tsc2 complex, a known negative regulator of TORC1 signaling. The GATOR1 complex, which functions as Gtr1 GAP, is essential for the TORC1 attenuation by the Ragulator-Rag complex, suggesting that Gtr1GDP-Gtr2 on vacuolar membranes moderates TORC1 signaling for optimal cellular response to nutrients

Effects of land use and climate change on water scarcity in rivers of the Western Ghats of India

This paper assesses the long-term combined effects of land use (LU) and climate change on river hydrology and water scarcity of two rivers of the Western Ghats of India. The historical LU changes were studied for four decades (1988–2016) using the maximum likelihood algorithm and the long-term LU (2016–2075) was estimated using the Dyna-CLUE prediction model. Five General Circulation Models (GCMs) were utilized to assess the effects of climate change (CC) and the Soil and Water Assessment Tool (SWAT) model was used for hydrological modeling of the two river catchments. To characterize granular effects of LU and CC on regional hydrology, a scenario approach was adopted and three scenarios depicting near-future (2006–2040), mid-future (2041–2070), and far-future (2071–2100) based on climate were established. The present rate of LU change indicated a reduction in forest cover by 20% and an increase in urbanized areas by 9.5% between 1988 and 2016. It was estimated that forest cover in the catchments may be expected to halve compared to the present-day LU (55% in 2016 to 23% in 2075), along with large-scale conversion to agricultural lands (13.5% in 2016 to 49.5% in 2075). As a result of changes to LU and forecasted climate, it was found that rivers in the Western Ghats of India might face scarcity of fresh water in the next two decades until the year 2040. However, because of large-scale LU conversion toward the year 2050, streamflow in rivers might increase as high as 70.94% at certain times of the year. Although an increase in streamflow is perceived favorable, the streamflow changes during summer and winter may be expected to affect the cropping calendar and crop yield. The changes to streamflow were also linked to a 4.2% increase in ecologically sensitive wetlands of the Aghanashini river catchment