Structural Changes in Dengue Virus When Exposed to a Temperature of 37°C

Previous binding studies of antibodies that recognized a partially or fully hidden epitope suggest that insect cell-derived dengue virus undergoes structural changes at an elevated temperature. This was confirmed by our cryo-electron microscopy images of dengue virus incubated at 37°C, where viruses change their surface from smooth to rough. Here we present the cryo-electron microscopy structures of dengue virus at 37°C. Image analysis showed four classes of particles. The three-dimensional (3D) map of one of these classes, representing half of the imaged virus population, shows that the E protein shell has expanded and there is a hole at the 3-fold vertices. Fitting E protein structures into the map suggests that all of the interdimeric and some intradimeric E protein interactions are weakened. The accessibility of some previously found cryptic epitopes on this class of particles is discussed.     

A Study of the Thermophysical Properties of Human Prostate Tumor Tissues in the Temperature Range from–160 to +40°C

Biophysics - A differential scanning calorimetry study of the specific isobaric heat capacity, phase-transition enthalpy, moisture content, and cryoscopic temperature for samples of benign and...     

K-Ras4B Remains Monomeric on Membranes over a Wide Range of Surface Densities and Lipid Compositions

Ras is a membrane-anchored signaling protein that serves as a hub for many signaling pathways and also plays a prominent role in cancer. The intrinsic behavior of Ras on the membrane has captivated the biophysics community in recent years, especially the possibility that it may form dimers. In this article, we describe results from a comprehensive series of experiments using fluorescence correlation spectroscopy and single-molecule tracking to probe the possible dimerization of natively expressed and fully processed K-Ras4B in supported lipid bilayer membranes. Key to these studies is the fact that K-Ras4B has its native membrane anchor, including both the farnesylation and methylation of the terminal cysteine, enabling detailed exploration of possible effects of cholesterol and lipid composition on K-Ras4B membrane organization. The results from all conditions studied indicate that full-length K-Ras4B lacks intrinsic dimerization capability. This suggests that any lateral organization of Ras in living cell membranes likely stems from interactions with other factors.     

Temperature dependent (37-15°C) anaerobic digestion of a trichloroethylene-contaminated wastewater

The impact of a trichloroethylene (TCE) contaminated wastewater on the microbial community structure of an anaerobic granular biomass at 15 °C compared to 37 °C was investigated. Four expanded granular sludge bed (EGSB) bioreactors (R1-R4) were employed in pairs at 37 and 15 °C. The influents of one of each pair were supplemented with increasing concentrations of TCE (max. 60 mg l⁻¹). At 37 °C, stable operation was maintained with 88% COD removal and >99% TCE removal at maximum influent TCE concentrations. R3 performance decreased at influent TCE concentration of 60 mg l⁻¹, although TCE removal rates of >97% were recorded. Archaeal community analysis via clone library and quantitative polymerase chain reaction (qPCR) analysis, and bacterial community analysis via denaturing gradient gel electrophoresis (DGGE), indicated that temperature resulted in a greater change in community structure than the presence of TCE, and clones related to cold adaptation of biomass were identified at 15 °C.     

Regulation of Integrin β1 Recycling to Lipid Rafts by Rab1a to Promote Cell Migration

Rab1a is a member of the Rab family of small GTPases with a well characterized function in the regulation of vesicle trafficking from the endoplasmic reticulum to the Golgi apparatus and within Golgi compartments. The integrin family heterodimeric transmembrane proteins serve as major receptors for extracellular matrix proteins, which play essential roles in cell adhesion and migration. Although effects on intracellular trafficking of integrins or other key cargos by Rab1a could influence cell migration, the regulatory mechanisms linking Rab1a to cell migration are not well understood. Here, we report identification of Rab1a as a novel regulator of cell migration using an unbiased RNAi screen targeting GTPases. Inhibition of Rab1a reduced integrin-mediated cell adhesion and spreading on fibronectins, reduced integrin β1 localization to lipid rafts, and decreased recycling of integrin β1 to the plasma membrane. Analysis of Rab1a effector molecules showed that p115 mediated Rab1a regulation of integrin recycling and lipid raft localization in cell migration. Taken together, these results suggest a novel function for Rab1a in the regulation of cell migration through controlling integrin β1 recycling and localization to lipid rafts via a specific downstream effector pathway.     

A Study of the Temperature Dependence of Tryptophan Fluorescence Lifetime in the Range of –170 to +20°С in Various Solvents

Biophysics - The temperature dependences (–170...+20°C) of the fluorescence lifetime of tryptophan molecules in an aqueous solution, in solutions of glycerol (50 and 75% by volume),...     

Survival of mouse oocytes after being cooled in a vitrification solution to -196°C at 95° to 70,000°C/min and warmed at 610° to 118,000°C/min: A new paradigm for cryopreservation by vitrification

There is great interest in achieving reproducibly high survivals of mammalian oocytes (especially human) after cryopreservation, but the results to date have not matched the interest. A prime cause of cell death is the formation of more than trace amounts of intracellular ice, and one strategy to avoid it is vitrification. In vitrification procedures, cells are loaded with high concentrations of glass-inducing solutes and cooled to −196 °C at rates high enough to presumably induce the glassy state. In the last decade, several devices have been developed to achieve very high cooling rates. Nearly all in the field have assumed that the cooling rate is the critical factor. The purpose of our study was to test that assumption by examining the consequences of cooling mouse oocytes in a vitrification solution at four rates ranging from 95 to 69,250 °C/min to −196 °C and for each cooling rate, subjecting them to five warming rates back above 0 °C at rates ranging from 610 to 118,000 °C/min. In samples warmed at the highest rate (118,000 °C/min), survivals were 70% to 85% regardless of the prior cooling rate. In samples warmed at the lowest rate (610 °C/min), survivals were low regardless of the prior cooling rate, but decreased from 25% to 0% as the cooling rate was increased from 95 to 69,000 °C/min. Intermediate cooling and warming rates gave intermediate survivals. The especially high sensitivity of survival to warming rate suggests that either the crystallization of intracellular glass during warming or the growth by recrystallization of small intracellular ice crystals formed during cooling are responsible for the lethality of slow warming.     

Degradation of polycaprolactone at 50 °C by a thermotolerant Aspergillus sp.

A thermotolerant Aspergillus sp. strain ST-01 degrading poly(-caprolactone) films was isolated. The polyester was degraded and assimilated giving 36 mg of cell from 100 mg sample and 10 mg yeast extract after 6 days at 50 °C. The degradation products were identified as succinic acid, butyric acid, valeric acid, and caproic acid. The isolate also degraded more than 90% film samples of polyhydroxybutyrate (PHB) and poly(tetramethylene succinate-co-tetramethylene adipate) at 50 °C.     

The Efficiency of Energy Transfer from Quantum Dots to Photosynthetic Reaction Centers of Rhodobacter sphaeroides in the Temperature Range of 100–310 K

Biophysics - The temperature dependence of the efficiency of energy transfer from polymer coated CdSe/CdS/ZnS quantum dots bearing terminal carboxyl groups to the reaction centers of purple...     

Synthesis of oligosaccharides by reversal of a fungal β-glucanase

Summary A crude commercial preparation of -glucanase fromPenicillium emersonii was used to synthesise glucose-containing oligosaccharides by condensation reactions in high concentrations of glucose at elevated temperature. Gentiobiose, laminaribiose, cellobiose, isomaltose and trehalose were identified as products. Heterooligosaccharides were produced by enzyme in some mixtures of glucose and an acceptor sugar. High performance ion-exchange chromatography was used to analyse synthetic products.     

Gametogenesis of Rainbow Trout Parasalmo mykiss Cultivated from Hatching to Sexual Maturity at a Temperature of Approximately 20°С

Journal of Ichthyology - Gonadal development during the first reproductive cycle is studied in rainbow trout Parasalmo mykiss cultivated at approximately 20°С. The cultivation of the...     

A Small Heat Shock Protein Enables Escherichia coli To Grow at a Lethal Temperature of 50°C Conceivably by Maintaining Cell Envelope Integrity

It is essential for organisms to adapt to fluctuating growth temperatures. Escherichia coli, a model bacterium commonly used in research and industry, has been reported to grow at a temperature lower than 46.5°C. Here we report that the heterologous expression of the 17-kDa small heat shock protein from the nematode Caenorhabditis elegans, CeHSP17, enables E. coli cells to grow at 50°C, which is their highest growth temperature ever reported. Strikingly, CeHSP17 also rescues the thermal lethality of an E. coli mutant deficient in degP, which encodes a protein quality control factor localized in the periplasmic space. Mechanistically, we show that CeHSP17 is partially localized in the periplasmic space and associated with the inner membrane of E. coli, and it helps to maintain the cell envelope integrity of the E. coli cells at the lethal temperatures. Together, our data indicate that maintaining the cell envelope integrity is crucial for the E. coli cells to grow at high temperatures and also shed new light on the development of thermophilic bacteria for industrial application.     

Development and evaluation of a trehalose-contained solution formula to preserve hUC-MSCs at 4°C

Human mesenchymal stem cells (hMSCs) hold great promise in cell therapy and regenerative medicine. Various preclinical and clinical trials have been carried out to illustrate the therapeutic potential of these cells. However, one major challenge for manufacturing clinical grade hMSCs is the requisition of current good manufacturing practice (cGMP) grade practices in cell isolation, processing, storage, and distribution. Development of non-toxic and animal serum-free preservation medium is critical for storage and distribution of mesenchymal stem cells (MSCs). In this study, we developed a solution formula that could preserve MSCs at 4°C for up to 3 weeks. In the solution, trehalose is a key ingredient for maintaining survival of MSCs. Among the concentrations investigated, 40 mM trehalose showed the best outcome with the viability maintained more than 92.7 ± 1.5% for 7 days. Cells preserved in the solution formula for 3 weeks still remained about 70% viability, and produced results similar to those of freshly harvested hMSCs in terms of growth kinetics, expression profile of cell surface antigens, and differentiation potential. In summary, storage of MSCs in the medium makes it far easier for transporting the cells from processing units to clinical sites.     

A comparison of the drying of chymotrypsin bound to bead cellulose by lyophilisation and in air at 25 to 70°C

Summary The effect was studied of the method of drying chymotrypsin attached to bead cellulose on its chemical and physical characteristics. These characteristics are not deteriorated when replacing the commonly used lyophilisation by fluid drying in the air stream. The preparations saved essentially the same proteolytic activity as well as stability even when increasing the drying air temperature to 70°C.     

The growth of dermatophytes at 4° C and 37° C; The relation of this character to others

Summary The ability of the generaEpidermophyton, Microsporon andTrichopyton to grow on some media at 4° C and 37° C was studied. It has been shown that specific differences exist among these fungi in the capability or rapidity of the growth at extreme temperatures.There is high positive correlation among perfect state production, isolation from the soil and growth at 4° C (group of characters A) and between pathogenicity and growth at 37° C (group of characters B). Between the groups A and B of characters exists a slighter negative correlation. Some prognosis about the five characters by certain species of dermatophytes may be given.     

Formation of Ice Microparticles in the Ovarian Fluid and Homogenates of Unfertilized Russian Sturgeon Eggs during Cooling to –196°C

Cryopreservation of fish and amphibian eggs is still an unsolved problem. The formation of ice crystals inside and outside cells acts as a main detrimental factor during a deep freezing of fish eggs, as well as crystal growth (recrystallization and repeated crystallization). Designing efficient cryoprotective media is necessary in order to avoid egg injury from freezing. Additional components that are present in a cryoprotective medium and reduce the thermomechanical stress and cracks of frozen tissues might increase oocyte survival after freezing–thawing. Natural components of eggs and the ovarian fluid are promising as such additives. The formation of ice microparticles was studied in thin layers (0.2 mm) of the ovarian fluid and components of Russian sturgeon egg homogenates upon their cooling to a liquid nitrogen temperature (–196°C). The processes of freezing, ice cracking, and microparticle formation were observed as the temperature was decreased gradually. The shape and size of ice microparticles were found to depend on the composition of the freezing solution. Certain fractions of egg homogenate were assumed to be suitable as components of a cryoprotective medium.

     

Temperature sensitivity of fructose-1,6-biphosphate aldolase accounts for the inability of the high-virulence clone ofStreptococcus agalactiae to grow at 40°C

A high-virulence clone of serotype IIIStreptoccus agalactiae causing invasive neonatal disease has recently been identified by multilocus enzyme electrophoresis and can be further distinguished by its inability to grow at 40°C in a chemically defined medium. The basis for the unusual growth inhibition at 40°C was examined in the present study and shown to be owing to a temperature-sensitive fructose-1,6-bisphosphate aldolase (fba). Crude enzyme preparations (75% saturated ammonium sulfate precipitates) of fba obtained from a high-virulence clone demonstrated a 75% reduction in aldolase activity when preincubated at 40°C for 30 min compared with 37°C. In contrast, fba from a serotype III isolate obtained from an asymptomatically colonized infant demonstrated <10% decrease in activity at 40°C. Comparison of another enzyme, lactate dehydrogenase (ldh), from both organisms indicated no loss in activity at 40°C compared with 37°C. Glyceraldehyde-3-phosphate, one of the end-products of fba activity, relieved growth inhibition at 40°C.     

Aqueous Synthesis of Peptide Thioesters from Amino Acids and a Thiol Using 1,1′-Carbonyldiimidazole

A new method was developed for the synthesis of peptide thioesters from free amino acids and thiols in water. This one-pot simple method involves two steps: (1) activation in water of an amino acid presumably as its N-carboxyanhydride (NCA) using 1,1′-carbonyldiimidazole (CDI), and (2) subsequent condensation of the activated amino acid-NCA in the presence of a thiol. With this method citrulline peptide thioesters containing up to 10 amino acid residues were prepared in a single reaction. This aqueous synthetic method provides a simple way to prepare peptide thioesters for studies of peptide replication involving ligation of peptide thioesters on peptide templates. The relevance of peptide replication to the origin-of-life process is supported by previous studies showing that amino acid thioesters (peptide thioester precursors) can be synthesized under prebiotic conditions by reaction of small sugars with ammonia and a thiol.