In vitro DNA-binding assays demonstrate that the heat shock transcription factor (HSF) from the yeast Saccharomyces cerevisiae can adopt an altered conformation when stressed. This conformation, reflected in a change in electrophoretic mobility, requires that two HSF trimers be bound to DNA. Single trimers do not show this change, which appears to represent an alteration in the cooperative interactions between trimers. HSF isolated from stressed cells displays a higher propensity to adopt this altered conformation. Purified HSF can be stimulated in vitro to undergo the conformational change by elevating the temperature or by exposing HSF to superoxide anion. Mutational analysis maps a region critical for this conformational change to the flexible loop between the minimal DNA-binding domain and the flexible linker that joins the DNA-binding domain to the trimerization domain. The significance of these findings is discussed in the context of the induction of the heat shock response by ischemic stroke, hypoxia, and recovery from anoxia, all known to stimulate the production of superoxide. INTRODUCTIONSince its discovery in 1962 (Ritossa, 1962), the heat shock response has been the focus of intensive investigation, leading to significant insights into protein folding and global gene regulation. In virtually all organisms, the heat shock response is manifested as the stress-induced, rapid, and dramatic increase in synthesis rates of a small number of protein chaperones. The chaperones bind to partially unfolded proteins and act to prevent their aggregation and to facilitate their refolding. Thus, this highly conserved system serves as an intricate means to protect cells against damage resulting from environmental stress.The most common stresses that induce the heat shock response are elevated temperature and oxidative stress. The latter is particularly important medically, because it typically results from the production of superoxide anion that occurs during partial oxygen deprivation or during the recovery from anoxia that occurs upon reperfusion after ischemia. Induction of the heat shock system upon recovery from anoxia may be universal; it has been described not only in mammalian systems but in Drosophila (Ritossa, 1964) and yeast (Brazzell and Ingolia, 1984). It has been unclear, however, how reperfusion triggers the heat shock response. Superoxide is rapidly converted to hydrogen peroxide, which can stimulate the production of the highly reactive hydroxyl radical, which, in turn, causes considerable "reperfusion damage." Thus, the heat shock response could be induced directly via one or more of these reactive oxygen species, or it could be induced by the protein damage caused by the hydroxyl radical.In eukaryotes, the heat shock response depends on modulating the activity (rather than the concentration) of a transcription factor. The heat shock transcription factor (HSF) is synthesized constitutively; its activity is regulated posttranslationally. Despite this commonality, different species show remarkably dis...
The low molecular weight (LMW) heat shock protein (HSP), HSP16.6, in the unicellular cyanobacterium, Synechocystis sp. PCC 6803, protects cells from elevated temperatures. A 95% reduction in the survival of mutant cells with an inactivated hsp16.6 was observed after exposure for 1 h at 47 degrees C. Wild-type cell survival was reduced to only 41%. HSP16.6 is also involved in the development of thermotolerance. After a sublethal heat shock at 43 degrees C for 1 h and subsequent challenge exposure at 49 degrees C for 40 min, mutant cells did not survive, while 64% of wild-type cells survived. Ultrastructural changes in the integrity of thylakoid membranes of heat-shocked mutant cells also are discussed. These results demonstrate an important protective role for HSP16.6 in the protection of cells and, in particular, thylakoid membrane against thermal stress.
The low molecular weight (LMW) heat shock protein (HSP) gene hsp16.6 was identified and cloned from the unicellular cyanobacterium Synechocystis sp. PCC 6803 through comparisons of genomic sequences and conserved gene sequences of the LMW HSPs. Hsp16.6 was isolated using PCR and cloned into the pGEMT plasmid. Hsp16.6 showed a significant increase in transcription after heat shock at 42 degreesC that indicated hsp16.6 was a heat shock gene. To determine the role that hsp16.6 plays in the heat shock response, a mutant Synechocystis cell line was generated. Cell growth and oxygen evolution rates of wild type and mutant cells were compared after heat shock. Results showed significantly decreased cell growth rates and a 40% reduction in oxygen evolution rates in mutants after heat shock treatments. These data indicate a protective role for hsp16.6 in the heat shock response.
In its 2019 report, The Skilled Technical Workforce: Crafting America's Science and Engineering Enterprise, the National Science Board recommended a national charge to create a skilled technical workforce (STW) driven by science and engineering. The RegenMed Development Organization (ReMDO), through its RegeneratOR Workforce Development Initiative, has taken on this challenge beginning with an assessment of regenerative medicine (RM) biomanufacturing knowledge, skills, and abilities (KSAs) needed for successful employment. While STW often refers only to associate degree or other prebaccalaureate prepared technicians, the RM biomanufacturing survey included responses related to baccalaureate prepared technicians. Three levels of preparation were articulated in the research: basic employability skills, core bioscience skills, and RM biomanufacturing technical skills. The first two of these skill levels have been defined by previous research and are generally accepted as foundational-the Common Employability Skills developed by the National Network of Business and Industry Associations and the Core Skill Standards for Bioscience Technicians developed by the National Center for the Biotechnology Workforce. Fifteen skill sets addressing the specialized needs of RM and related biotechnology sectors were identified in the ReMDO survey, defining a third level of KSAs needed for entry-level employment in RM biomanufacturing. The purpose of the article is to outline the KSAs necessary for RM biomanufacturing, quantify the skills gap that currently exists between skills required by employers and those acquired by employees and available in the labor market, and make recommendations for the application of these findings.
This research focuses on the design and fabrication of a MEMS-based pressure sensor to measure the internal pressure of a thermal management system for fuel cell electric vehicles. The principle of measurement of the pressure is converting the piezoresistor value on a diaphragm deformed by a pressure difference into an output voltage. The diaphragm should operate normally for pressure sensing even harsh environments such as those in automobiles. However, the pressure sensor outputs abnormal values with an offset voltage due to physical and chemical factors during driving. One of the reasons is the polymer reaction originating from the coolant of the thermal management system between the polymer and sensor diaphragm. In this paper, the reason for abnormal operation is analyzed by measurement with a microscope, computational fluid dynamics, finite element method, and reproducible tests. A solution is suggested and a revised pressure sensor is proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.