Effect of trehalose on protein structure

daf-16/FoxO promotes gluconeogenesis and trehalose synthesis during starvation to support survival

daf-16/FoxO is required to survive starvation in Caenorhabditis elegans, but how daf-16IFoxO promotes starvation resistance is unclear. We show that daf-16/FoxO restructures carbohydrate metabolism by driving carbon flux through the glyoxylate shunt and gluconeogenesis and into synthesis of trehalose, a disaccharide of glucose. Trehalose is a well-known stress protectant, capable of preserving membrane organization and protein structure during abiotic stress. Metabolomic, genetic, and pharmacological analyses confirm increased trehalose synthesis and further show that trehalose not only supports survival as a stress protectant but also serves as a glycolytic input. Furthermore, we provide evidence that metabolic cycling between trehalose and glucose is necessary for this dual function of trehalose. This work demonstrates that daf-16/FoxO promotes starvation resistance by shifting carbon metabolism to drive trehalose synthesis, which in turn supports survival by providing an energy source and acting as a stress protectant.

Most animals rarely have access to a constant supply of food, and so have evolved ways to cope with times of plenty and times of shortage. Insulin is a hormone that travels throughout the body to signal when an animal is well fed. Insulin signaling inhibits the activity of a protein called FoxO, which otherwise switches on and off hundreds of genes to control the starvation response.

The roundworm, Caenorhabditis elegans, has been well studied in the laboratory, and often has to cope with starvation in the wild. These worms can pause their development if no food is available, or divert to a different developmental path if they anticipate that food will be short in future. As with more complex animals, the worm responds to starvation by reducing insulin-like signaling, which in turn activates a FoxO protein called daf-16. When the worms stop feeding, daf-16 is switched on, which is crucial for survival.

It was known how daf-16 stops the roundworm’s development, but it was not known how it helps the worms to survive starvation. Now, Hibshman et al. have compared normal roundworm larvae to larvae that are missing the gene for daf-16 to determine how this protein influences the roundworm’s ability to survive starvation.

The worms were examined with and without food, to look for which genes were switched on and off by daf-16 during starvation. This revealed that daf-16 controls metabolism, activating a metabolic shortcut that makes the worms produce glucose and begin turning it into another type of sugar, called trehalose. This sugar usually promotes survival in conditions where water is limiting, like dehydration and high salt, but it can also be broken down to release energy. The levels of trehalose in the worms rose within hours of the onset of starvation.

To confirm the importance of trehalose in surviving starvation, roundworms with mutations in genes involved in glucose or trehalose production were examined, as was the effect of giving starving worms glucose or trehalose. Disrupting the production of sugars caused the worms to die sooner of starvation, while supplementing with sugar had the opposite effect meaning the worms survived for longer.

Taken together, these findings reveal that daf-16 protects against starvation by shifting metabolism towards the production of trehalose. This helps worms to survive by both protecting them from stress and providing them with a source of energy. These findings not only extend the current understanding of how animals respond to starvation, but could also lead to improved understanding of diseases where this response goes wrong, including diabetes and obesity.

Tailoring the Oxidative Stress Tolerance of Clostridium tyrobutyricum CCTCC W428 by Introducing Trehalose Biosynthetic Capability

Fermentations employing anaerobes always suffer from the restriction of stringent anaerobic conditions during the production of bulk and fine chemicals. This work aims to improve the oxidative stress tolerance of C. tyrobutyricum CCTCC W428, an ideal butyric-acid-producing anaerobe, via the introduction of trehalose biosynthesis capability. Compared with the wild type, the engineered strain showed a wider substrate spectrum, an improved metabolic profile, and a significantly increased specific growth rate upon aeration and acid challenge. Molecular simulation experiments indicated that CoA transferase maintained its native folded state when protected by the trehalose system. Furthermore, qRT-PCR was combined assays for acid-related enzyme activities under various conditions to verify the effects of trehalose. These results demonstrate that introducing a trehalose biosynthetic pathway, which is redundant for the metabolism of C. tyrobutyricum, can increase the robustness of the host to achieve a better oxidative resistance.

Revisiting Escherichia coli as microbial factory for enhanced production of human serum albumin

BACKGROUND

Human serum albumin (HSA)-one of the most demanded therapeutic proteins with immense biotechnological applications-is a large multidomain protein containing 17 disulfide bonds. The current source of HSA is human blood plasma which is a limited and unsafe source. Thus, there exists an indispensable need to promote non-animal derived recombinant HSA (rHSA) production. Escherichia coli is one of the most convenient hosts which had contributed to the production of more than 30% of the FDA approved recombinant pharmaceuticals. It grows rapidly and reaches high cell density using inexpensive and simple subst-rates. E. coli derived recombinant products have more economic potential as fermentation processes are cheaper compared to the other expression hosts. The major bottleneck in exploiting E. coli as a host for a disulfide-rich multidomain protein is the formation of aggregates of overexpressed protein. The majority of the expressed HSA forms inclusion bodies (more than 90% of the total expressed rHSA) in the E. coli cytosol. Recovery of functional rHSA from inclusion bodies is not preferred because it is difficult to obtain a large multidomain disulfide bond rich protein like rHSA in its functional native form. Purification is tedious, time-consuming, laborious and expensive. Because of such limitations, the E. coli host system was neglected for rHSA production for the past few decades despite its numerous advantages.

RESULTS

In the present work, we have exploited the capabilities of E. coli as a host for the enhanced functional production of rHSA (~ 60% of the total expressed rHSA in the soluble fraction). Parameters like intracellular environment, temperature, induction type, duration of induction, cell lysis conditions etc. which play an important role in enhancing the level of production of the desired protein in its native form in vivo have been optimized. We have studied the effect of assistance of different types of exogenously employed chaperone systems on the functional expression of rHSA in the E. coli host system. Different aspects of cell growth parameters during the production of rHSA in presence and absence of molecular chaperones in E. coli have also been studied.

CONCLUSION

In the present case, we have filled in the gap in the literature by exploiting the E. coli host system, which is fast-growing and scalable at the low cost of fermentation, as a microbial factory for the enhancement of functional production of rHSA, a crucial protein for therapeutic and biotechnological applications.

A Printed Multicomponent Paper Sensor for Bacterial Detection

We present a simple all-in-one paper-based sensor for E. coli detection using a composite ink made of a fluorogenic DNAzyme probe for bacterial recognition and signal generation, lysozyme that lyses whole bacterial cells, and pullulan/trehalose sugars that stabilize printed bioactive molecules. The paper sensor is capable of producing a fluorescence signal as a readout within 5 minutes upon contacting E. coli, can achieve a limit of detection of 100 cells/mL, in a variety of sample matrixes, without sample enrichment, and remains stable for at least 6 months when stored at ambient temperature. Therefore, this simple paper sensor provides rapid bacterial testing on site, and can be shipped and stored under ambient conditions to benefit users living in resource-limited regions.

Tracking Reactive Water and Hydrogen-Bonding Networks in Photosynthetic Oxygen Evolution

In oxygenic photosynthesis, photosystem II (PSII) converts water to molecular oxygen through four photodriven oxidation events at a Mn₄CaO₅ cluster. A tyrosine, YZ (Y161 in the D1 polypeptide), transfers oxidizing equivalents from an oxidized, primary chlorophyll donor to the metal center. Calcium or its analogue, strontium, is required for activity. The Mn₄CaO₅ cluster and YZ are predicted to be hydrogen bonded in a water-containing network, which involves amide carbonyl groups, amino acid side chains, and water. This hydrogen-bonded network includes amino acid residues in intrinsic and extrinsic subunits. One of the extrinsic subunits, PsbO, is intrinsically disordered. This extensive (35 Å) network may be essential in facilitating proton release from substrate water. While it is known that some proteins employ internal water molecules to catalyze reactions, there are relatively few methods that can be used to study the role of water. In this Account, we review spectroscopic evidence from our group supporting the conclusion that the PSII hydrogen-bonding network is dynamic and that water in the network plays a direct role in catalysis. Two approaches, transient electron paramagnetic resonance (EPR) and reaction-induced FT-IR (RIFT-IR) spectroscopies, were used. The EPR experiments focused on the decay kinetics of YZ• via recombination at 190 K and the solvent isotope, pH, and calcium dependence of these kinetics. The RIFT-IR experiments focused on shifts in amide carbonyl frequencies, induced by photo-oxidation of the metal cluster, and on the isotope-based assignment of bands to internal, small protonated water clusters at 190, 263, and 283 K. To conduct these experiments, PSII was prepared in selected steps along the catalytic pathway, the S_n state cycle (n = 0-4). This cycle ultimately generates oxygen. In the EPR studies, S-state dependent changes were observed in the YZ• lifetime and in its solvent isotope effect. The YZ• lifetime depended on the presence of calcium at pH 7.5, but not at pH 6.0, suggesting a two-donor model for PCET. At pH 6.0 or 7.5, barium and ammonia both slowed the rate of YZ• recombination, consistent with disruption of the hydrogen-bonding network. In the RIFT-IR studies of the S state transitions, infrared bands associated with the transient protonation and deprotonation of internal waters were identified by D₂O and H₂¹⁸O labeling. The infrared bands of these protonated water clusters, W_n⁺ (or nH₂O(H₃O)⁺, n = 5-6), exhibited flash dependence and were produced during the S₁ to S₂ and S₃ to S₀ transitions. Calcium dependence was observed at pH 7.5, but not at pH 6.0. S-state induced shifts were observed in amide C═O frequencies during the S₁ to S₂ transition and attributed to alterations in hydrogen bonding, based on ammonia sensitivity. In addition, isotope editing of the extrinsic subunit, PsbO, established that amide vibrational bands of this lumenal subunit respond to the S state transitions and that PsbO is a structural template for the reaction center. Taken together, these spectroscopic results support the hypothesis that proton transfer networks, extending from YZ to PsbO, play a functional and dynamic role in photosynthetic oxygen evolution.

Inhalable siRNA-loaded nano-embedded microparticles engineered using microfluidics and spray drying

Medicines based on small interfering RNA (siRNA) are promising for the treatment of a number of lung diseases. However, efficient delivery systems and design of stable dosage forms are required for inhalation therapy, as well as cost-effective methods for manufacturing of the final product. In this study, a 3D-printed micromixer was used for preparation of siRNA-dendrimer nanocomplexes, which were subsequently processed into microparticle-based dry powders for inhalation using spray drying. By applying the disposable micromixer, nanocomplexes were prepared of an average hydrodynamic diameter comparable to that of nanocomplexes prepared by manual mixing, but with narrower size distribution and low batch-to-batch variation. The nanocomplexes were processed into nanoembedded microparticles using different saccharide excipients. Data showed that siRNA integrity and bioactivity are retained after processing, and nanocomplexes could be reconstituted from the dry powders. The amorphous saccharide excipients trehalose and inulin provided better stabilization than crystalline mannitol, and they enabled full reconstitution of the nanocomplexes. In particular, a binary mixture of trehalose and inulin showed optimal stabilization, and enhanced cellular uptake and gene silencing efficiency. This study demonstrates that inexpensive and scalable micromixers can be used to optimize the production of siRNA-dendrimer nanocomplexes, and they can be applied in combination with spray drying for the engineering of dry powder formulations suitable for delivery of siRNA to the therapeutic target site.

Transcriptomic and metabolomic profiles of Chinese citrus fly, Bactrocera minax (Diptera: Tephritidae), along with pupal development provide insight into diapause program

The Chinese citrus fly, Bactrocera minax (Enderlein), is a devastating citrus pest in Asia. This univoltine insect enters obligatory pupal diapause in each generation, while little is known about the course and the molecular mechanisms of diapause. In this study, the course of diapause was determined by measuring the respiratory rate throughout the pupal stage. In addition, the variation of transcriptomic and metabolomic profiles of pupae at five developmental stages (pre-, early-, middle-, late-, and post-diapause) were evaluated by next-generation sequencing technology and ¹H nuclear magnetic resonance spectroscopy (NMR), respectively. A total of 4,808 genes were significantly altered in ten pairwise comparisons, representing major shifts in metabolism and signal transduction as well as endocrine system and digestive system. Gene expression profiles were validated by qRT-PCR analysis. In addition, 48 metabolites were identified and quantified by ¹H NMR. Nine of which significantly contributed to the variation in the metabolomic profiles, especially proline and trehalose. Moreover, the samples collected within diapause maintenance (early-, middle-, and late-diapause) only exhibited marginal transcriptomic and metabolomic variation with each other. These findings greatly improve our understanding of B. minax diapause and lay the foundation for further pertinent studies.

Comparative Genome Analysis Provides Insights into Both the Lifestyle of Acidithiobacillus ferrivorans Strain CF27 and the Chimeric Nature of the Iron-Oxidizing Acidithiobacilli Genomes

The iron-oxidizing species Acidithiobacillus ferrivorans is one of few acidophiles able to oxidize ferrous iron and reduced inorganic sulfur compounds at low temperatures (<10°C). To complete the genome of At. ferrivorans strain CF27, new sequences were generated, and an update assembly and functional annotation were undertaken, followed by a comparative analysis with other Acidithiobacillus species whose genomes are publically available. The At. ferrivorans CF27 genome comprises a 3,409,655 bp chromosome and a 46,453 bp plasmid. At. ferrivorans CF27 possesses genes allowing its adaptation to cold, metal(loid)-rich environments, as well as others that enable it to sense environmental changes, allowing At. ferrivorans CF27 to escape hostile conditions and to move toward favorable locations. Interestingly, the genome of At. ferrivorans CF27 exhibits a large number of genomic islands (mostly containing genes of unknown function), suggesting that a large number of genes has been acquired by horizontal gene transfer over time. Furthermore, several genes specific to At. ferrivorans CF27 have been identified that could be responsible for the phenotypic differences of this strain compared to other Acidithiobacillus species. Most genes located inside At. ferrivorans CF27-specific gene clusters which have been analyzed were expressed by both ferrous iron-grown and sulfur-attached cells, indicating that they are not pseudogenes and may play a role in both situations. Analysis of the taxonomic composition of genomes of the Acidithiobacillia infers that they are chimeric in nature, supporting the premise that they belong to a particular taxonomic class, distinct to other proteobacterial subgroups.

Exploiting macrophage autophagy-lysosomal biogenesis as a therapy for atherosclerosis

Macrophages specialize in removing lipids and debris present in the atherosclerotic plaque. However, plaque progression renders macrophages unable to degrade exogenous atherogenic material and endogenous cargo including dysfunctional proteins and organelles. Here we show that a decline in the autophagy–lysosome system contributes to this as evidenced by a derangement in key autophagy markers in both mouse and human atherosclerotic plaques. By augmenting macrophage TFEB, the master transcriptional regulator of autophagy–lysosomal biogenesis, we can reverse the autophagy dysfunction of plaques, enhance aggrephagy of p62-enriched protein aggregates and blunt macrophage apoptosis and pro-inflammatory IL-1β levels, leading to reduced atherosclerosis. In order to harness this degradative response therapeutically, we also describe a natural sugar called trehalose as an inducer of macrophage autophagy–lysosomal biogenesis and show trehalose's ability to recapitulate the atheroprotective properties of macrophage TFEB overexpression. Our data support this practical method of enhancing the degradative capacity of macrophages as a therapy for atherosclerotic vascular disease.

Dysfunction of autophagy in plaque macrophages aggravates atherosclerosis. Here the authors show that induction of macrophage autophagy–lysosomal biogenesis either genetically by overexpression of the master transcriptional regulator of this process, TFEB, or pharmacologically with trehalose is atheroprotective.

Expression patterns of members of the ethylene signaling-related gene families in response to dehydration stresses in cassava

Drought is the one of the most important environment stresses that restricts crop yield worldwide. Cassava (Manihot esculenta Crantz) is an important food and energy crop that has many desirable traits such as drought, heat and low nutrients tolerance. However, the mechanisms underlying drought tolerance in cassava are unclear. Ethylene signaling pathway, from the upstream receptors to the downstream transcription factors, plays important roles in environmental stress responses during plant growth and development. In this study, we used bioinformatics approaches to identify and characterize candidate Manihot esculenta ethylene receptor genes and transcription factor genes. Using computational methods, we localized these genes on cassava chromosomes, constructed phylogenetic trees and identified stress-responsive cis-elements within their 5’ upstream regions. Additionally, we measured the trehalose and proline contents in cassava fresh leaves after drought, osmotic, and salt stress treatments, and then it was found that the regulation patterns of contents of proline and trehalose in response to various dehydration stresses were differential, or even the opposite, which shows that plant may take different coping strategies to deal with different stresses, when stresses come. Furthermore, expression profiles of these genes in different organs and tissues under non-stress and abiotic stress were investigated through quantitative real-time PCR (qRT-PCR) analyses in cassava. Expression profiles exhibited clear differences among different tissues under non-stress and various dehydration stress conditions. We found that the leaf and tuberous root tissues had the greatest and least responses, respectively, to drought stress through the ethylene signaling pathway in cassava. Moreover, tuber and root tissues had the greatest and least reponses to osmotic and salt stresses through ethylene signaling in cassava, respectively. These results show that these plant tissues had differential expression levels of genes involved in ethylene signaling in response to the stresses tested. Moreover, after several gene duplication events, the spatiotemporally differential expression pattern of homologous genes in response to abiotic and biotic stresses may imply their functional diversity as a mechanism for adapting to the environment. Our data provide a framework for further research on the molecular mechanisms of cassava resistance to drought stress and provide a foundation for breeding drought-resistant new cultivars.

Probiotic engineering: towards development of robust probiotic strains with enhanced functional properties and for targeted control of enteric pathogens

There is a growing concern about the increase in human morbidity and mortality caused by foodborne pathogens. Antibiotics were and still are used as the first line of defense against these pathogens, but an increase in the development of bacterial antibiotic resistance has led to a need for alternative effective interventions. Probiotics are used as dietary supplements to promote gut health and for prevention or alleviation of enteric infections. They are currently used as generics, thus making them non-specific for different pathogens. A good understanding of the infection cycle of the foodborne pathogens as well as the virulence factors involved in causing an infection can offer an alternative treatment with specificity. This specificity is attained through the bioengineering of probiotics, a process by which the specific gene of a pathogen is incorporated into the probiotic. Such a process will subsequently result in the inhibition of the pathogen and hence its infection. Recombinant probiotics offer an alternative novel therapeutic approach in the treatment of foodborne infections. This review article focuses on various strategies of bioengineered probiotics, their successes, failures and potential future prospects for their applications.

Trehalose supplementation reduces hepatic endoplasmic reticulum stress and inflammatory signaling in old mice

The accumulation of damaged proteins can perturb cellular homeostasis and provoke aging and cellular damage. Quality control systems, such as the unfolded protein response (UPR), inflammatory signaling and protein degradation, mitigate the residence time of damaged proteins. In the present study, we have examined the UPR and inflammatory signaling in the liver of young (~6 months) and old (~28 months) mice (n=8/group), and the ability of trehalose, a compound linked to increased protein stability and autophagy, to counteract age-induced effects on these systems. When used, trehalose was provided for 4 weeks in the drinking water immediately prior to sacrifice (n=7/group). Livers from old mice were characterized by activation of the UPR, increased inflammatory signaling and indices of liver injury. Trehalose treatment reduced the activation of the UPR and inflammatory signaling, and reduced liver injury. Reductions in proteins involved in autophagy and proteasome activity observed in old mice were restored following trehalose treatment. The autophagy marker, LC3B-II, was increased in old mice treated with trehalose. Metabolomics analyses demonstrated that reductions in hexosamine biosynthetic pathway metabolites and nicotinamide in old mice were restored following trehalose treatment. Trehalose appears to be an effective intervention to reduce age-associated liver injury and mitigate the need for activation of quality control systems that respond to disruption of proteostasis.

Lactic acid bacteria - promising vaccine vectors: possibilities, limitations, doubts

Gram‐positive, nonpathogenic lactic acid bacteria (LAB) are considered to be promising candidates for the development of novel, safe production and delivery systems of heterologous proteins. Recombinant LAB strains were shown to elicit specific systemic and mucosal immune responses against selected antigens. For this reason, this group of bacteria is considered as a potential replacement of classical, often pathogenic, attenuated microbial carriers. Mucosal administration of recombinant LAB, especially via the best explored and universal oral route, offers many advantages in comparison to systemic inoculation, and is attractive from the immunological and practical point of view. Research aimed at designing efficient, mucosally applied vaccines in combination with improved immunization efficiency, monitoring of in vivo antigen production, determination of optimal dose for vaccination, strain selection and characterization is a priority in modern vaccinology. This paper summarizes and organizes the available knowledge on the application of LAB as live oral vaccine vectors. It constitutes a valuable source of general information for researchers interested in mucosal vaccine development and constructing LAB strains with vaccine potential.

Dry Preservation of Spermatozoa: Considerations for Different Species

The current gold standard for sperm preservation is storage at cryogenic temperatures. Dry preservation is an attractive alternative, eliminating the need for ultralow temperatures, reducing storage maintenance costs, and providing logistical flexibility for shipping. Many seeds and anhydrobiotic organisms are able to survive extended periods in a dry state through the accumulation of intracellular sugars and other osmolytes and are capable of returning to normal physiology postrehydration. Using techniques inspired by nature's adaptations, attempts have been made to dehydrate and dry preserve spermatozoa from a variety of species. Most of the anhydrous preservation research performed to date has focused on mouse spermatozoa, with only a small number of studies in nonrodent mammalian species. There is a significant difference between sperm function in rodent and nonrodent mammalian species with respect to centrosomal inheritance. Studies focused on reproductive technologies have demonstrated that in nonrodent species, the centrosome must be preserved to maintain sperm function as the spermatozoon centrosome contributes the dominant nucleating seed, consisting of the proximal centriole surrounded by pericentriolar components, onto which the oocyte's centrosomal material is assembled. Preservation techniques used for mouse sperm may therefore not necessarily be applicable to nonrodent spermatozoa. The range of technologies used to dehydrate sperm and the effect of processing and storage conditions on fertilization and embryogenesis using dried sperm are reviewed in the context of reproductive physiology and cellular morphology in different species.

Targeted proteome analysis of single-gene deletion strains of Saccharomyces cerevisiae lacking enzymes in the central carbon metabolism

Central carbon metabolism is controlled by modulating the protein abundance profiles of enzymes that maintain the essential systems in living organisms. In this study, metabolic adaptation mechanisms in the model organism Saccharomyces cerevisiae were investigated by direct determination of enzyme abundance levels in 30 wild type and mutant strains. We performed a targeted proteome analysis using S. cerevisiae strains that lack genes encoding the enzymes responsible for central carbon metabolism. Our analysis revealed that at least 30% of the observed variations in enzyme abundance levels could be explained by global regulatory mechanisms. A enzyme-enzyme co-abundance analysis revealed that the abundances of enzyme proteins involved in the trehalose metabolism and glycolysis changed in a coordinated manner under the control of the transcription factors for global regulation. The remaining variations were derived from local mechanisms such as a mutant-specific increase in the abundances of remote enzymes. The proteome data also suggested that, although the functional compensation of the deficient enzyme was attained by using more resources for protein biosynthesis, available resources for the biosynthesis of the enzymes responsible for central metabolism were not abundant in S. cerevisiae cells. These results showed that global and local regulation of enzyme abundance levels shape central carbon metabolism in S. cerevisiae by using a limited resource for protein biosynthesis.

Recombinant Lactococcus lactis Expressing Haemagglutinin from a Polish Avian H5N1 Isolate and Its Immunological Effect in Preliminary Animal Trials

Lactic acid bacteria (LAB) are Gram-positive, nonpathogenic microorganisms that are gaining much interest as antigen producers for development of live vaccine vectors. Heterologous proteins of different origin have been successfully expressed in various LAB species, including Lactococcus lactis. Recombinant L. lactis strains have been shown to induce specific local and systemic immune responses against various antigens. Our study aimed at constructing a L. lactis strain expressing haemagglutinin of a Polish avian H5H1 influenza isolate and examining its effect on animals. Expression of the cloned H5 gene was achieved using the nisin-controlled gene expression system. Detection of the intracellular H5 antigen produced in L. lactis was performed by Western blot analysis and confirmed using mass spectrometry. The potential of L. lactis recombinant cells to induce an immune response was examined by setting up preliminary immunization trials on chickens and mice. Obtained sera were tested for specific antibodies by ELISA assays. The results of these studies are a promising step toward developing a vaccine against the bird flu using Lactococcus lactis cells as bioreactors for efficient antigen production and delivery to the mucosal surface.

Effects of storage conditions on the stability of spray dried, inhalable bacteriophage powders

This study aimed to develop inhalable powders containing phages active against antibiotic-resistant Pseudomonas aeruginosa for pulmonary delivery. A Pseudomonas phage, PEV2, was spray dried into powder matrices comprising of trehalose (0-80%), mannitol (0-80%) and l-leucine (20%). The resulting powders were stored at various relative humidity (RH) conditions (0, 22 and 60% RH) at 4°C. The phage stability and in vitro aerosol performance of the phage powders were examined at the time of production and after 1, 3 and 12 months storage. After spray drying, a total of 1.3 log titer reduction in phage was observed in the formulations containing 40%, 60% and 80% trehalose, whereas 2.4 and 5.1 log reductions were noted in the formulations containing 20% and no trehalose, respectively. No further reduction in titer occurred for powders stored at 0 and 22% RH even after 12 months, except the formulation containing no trehalose. The 60% RH storage condition had a destructive effect such that no viable phages were detected after 3 and 12 months. When aerosolised, the total lung doses for formulations containing 40%, 60% and 80% trehalose were similar (in the order of 10⁵ pfu). The results demonstrated that spray drying is a suitable method to produce stable phage powders for pulmonary delivery. A powder matrix containing ≥40% trehalose provided good phage preservation and aerosol performances after storage at 0 and 22% RH at 4°C for 12 months.

Effect of Trehalose and Trehalose Transport on the Tolerance of Clostridium perfringens to Environmental Stress in a Wild Type Strain and Its Fluoroquinolone-Resistant Mutant

Trehalose has been shown to protect bacterial cells from environmental stress. Its uptake and osmoprotective effect in Clostridium perfringens were investigated by comparing wild type C. perfringens ATCC 13124 with a fluoroquinolone- (gatifloxacin-) resistant mutant. In a chemically defined medium, trehalose and sucrose supported the growth of the wild type but not that of the mutant. Microarray data and qRT-PCR showed that putative genes for the phosphorylation and transport of sucrose and trehalose (via phosphoenolpyruvate-dependent phosphotransferase systems, PTS) and some regulatory genes were downregulated in the mutant. The wild type had greater tolerance than the mutant to salts and low pH; trehalose and sucrose further enhanced the osmotolerance of the wild type to NaCl. Expression of the trehalose-specific PTS was lower in the fluoroquinolone-resistant mutant. Protection of C. perfringens from environmental stress could therefore be correlated with the ability to take up trehalose.

Trehalase plays a role in macrophage colonization and virulence of Burkholderia pseudomallei in insect and mammalian hosts

Trehalose is a disaccharide formed from two glucose molecules. This sugar molecule can be isolated from a range of organisms including bacteria, fungi, plants and invertebrates. Trehalose has a variety of functions including a role as an energy storage molecule, a structural component of glycolipids and plays a role in the virulence of some microorganisms. There are many metabolic pathways that control the biosynthesis and degradation of trehalose in different organisms. The enzyme trehalase forms part of a pathway that converts trehalose into glucose. In this study we set out to investigate whether trehalase plays a role in both stress adaptation and virulence of Burkholderia pseudomallei. We show that a trehalase deletion mutant (treA) had increased tolerance to thermal stress and produced less biofilm than the wild type B. pseudomallei K96243 strain. We also show that the ΔtreA mutant has reduced ability to survive in macrophages and that it is attenuated in both Galleria mellonella (wax moth larvae) and a mouse infection model. This is the first report that trehalase is important for bacterial virulence.

Metabolic engineering of Saccharomyces cerevisiae for improvement in stresses tolerance

Lignocellulosic biomass is an attractive low-cost feedstock for bioethanol production. During bioethanol production, Saccharomyces cerevisiae, the common used starter, faces several environmental stresses such as aldehydes, glucose, ethanol, high temperature, acid, alkaline and osmotic pressure. The aim of this study was to construct a genetic recombinant S. cerevisiae starter with high tolerance against various environmental stresses. Trehalose-6-phosphate synthase gene (tps1) and aldehyde reductase gene (ari1) were co-overexpressed in nth1 (coded for neutral trehalase gene, trehalose degrading enzyme) deleted S. cerevisiae. The engineered strain exhibited ethanol tolerance up to 14% of ethanol, while the growth of wild strain was inhibited by 6% of ethanol. Compared with the wild strain, the engineered strain showed greater ethanol yield under high stress condition induced by combining 30% glucose, 30 mM furfural and 30 mM 5-hydroxymethylfurfural (HMF).

Natural zwitterionic betaine enables cells to survive ultrarapid cryopreservation

Cryoprotectants (CPAs) play a critical role in cryopreservation because they can resist the cell damage caused by the freezing process. Current state-of-the-art CPAs are mainly based on an organic solvent dimethyl sulfoxide (DMSO), and several DMSO-cryopreserved cell products have been brought to market. However, the intrinsic toxicity and complex freezing protocol of DMSO still remain as the bottleneck of the wide use for clinical applications. Herein, we reported that betaine, a natural zwitterionic molecule, could serve as a nontoxic and high efficient CPA. At optimum concentration of betaine, different cell types exhibited exceptional post-thaw survival efficiency with ultrarapid freezing protocol, which was straightforward, cost efficient but difficult to succeed using DMSO. Moreover, betaine showed negligible cytotoxicity even after long-term exposure of cells. Mechanistically, we hypothesized that betaine could be ultra-rapidly taken up by cells for intracellular protection during the freezing process. This technology unlocks the possibility of alternating the traditional toxic CPAs and is applicable to a variety of clinical applications.

Current status in biotechnological production and applications of glycolipid biosurfactants

Biosurfactants are natural compounds with surface activity and emulsifying properties produced by several types of microorganisms and have been considered an interesting alternative to synthetic surfactants. Glycolipids are promising biosurfactants, due to low toxicity, biodegradability, and chemical stability in different conditions and also because they have many biological activities, allowing wide applications in different fields. In this review, we addressed general information about families of glycolipids, rhamnolipids, sophorolipids, mannosylerythritol lipids, and trehalose lipids, describing their chemical and surface characteristics, recent studies using alternative substrates, and new strategies to improve of production, beyond their specificities. We focus in providing recent developments and trends in biotechnological process and medical and industrial applications.

Trehalose prevents aggregation of exosomes and cryodamage

Exosomes are important mediators in intercellular communication. Released by many cell types, they transport proteins, lipids, and nucleic acids to distant recipient cells and contribute to important physiopathological processes. Standard current exosome isolation methods based on differential centrifugation protocols tend to induce aggregation of particles in highly concentrated suspensions and freezing of exosomes can induce damage and inconsistent biological activity. Trehalose is a natural, non-toxic sugar widely used as a protein stabilizer and cryoprotectant by the food and drug industry. Here we report that addition of 25 mM trehalose to pancreatic beta-cell exosome-like vesicle isolation and storage buffer narrows the particle size distribution and increases the number of individual particles per microgram of protein. Repeated freeze-thaw cycles induce an increase in particle concentration and in the width of the size distribution for exosome-like vesicles stored in PBS, but not in PBS 25 mM trehalose. No signs of lysis or incomplete vesicles were observed by cryo-electron tomography in PBS and trehalose samples. In macrophage immune assays, beta-cell extracellular vesicles in trehalose show consistently higher TNF-alpha cytokine secretion stimulation indexes suggesting improved preservation of biological activity. The addition of trehalose might be an attractive means to standardize experiments in the field of exosome research and downstream applications.

Trehalose preincubation increases mesenchymal (CD271⁺) stem cells post-cryopreservation viability

Background: Dimethyl sulfoxide (Me2SO) is a common cryoprotective agent widely used in cell preservation system. Me2SO is currently known to cause epigenetic changes which are  critical in stem cells development and cellular differentiation. Therefore, it is imperative to develop cryopreservation techniques that protect cellular functions and avert Me2SO adverse effect. Trehalose was able to protect organism in extreme condition such as dehydration and cold. This study aimed to verify the protective effect of trehalose preincubation procedure in cryopreservation.Methods: The study was conducted using experimental design. Thawed mesenchymal (CD271+) stem cells from YARSI biorepository were used for the experiment. Trehalose preincubation was performed for 1 hour, internalized trehalose was confirmed by FTIR-ATR measurement. Three groups consisted of (1) cryopreserved without trehalose preincubation, (2) cryopreserved with trehalose preincubation, and (3) did not undergo cryopreservation were evaluated after 24 hours in LN2 for viability in culture. The absorbance from each group was measured at 450 nm. The analysis performed using paired student t test.Results: Viability of thawed mesenchymal (CD271+) stem cells that undergo trehalose preincubation prior cryopreservation was significantly higher (p<0.05) compared to group without trehalose preincubation. Higher viability observed between group with trehalose preincubation compared with controlled group suggests protection to trypsinization. Mesenchymal (CD271+) stem cells incubated for 1 hour in 100 mM trehalose supplemented medium  results in 15%  trehalose loading efficiency.Conclusion: These findings confirm the protective effect of trehalose preincubation in cryopreservation. Future research should be directed to elucidate the trehalose internalization mechanism and eventually the protective mechanism of trehalose in mammalian cell cryopreservation.

Quantitative Analysis of Apisin, a Major Protein Unique to Royal Jelly

Apisin, a protein that is unique to royal jelly (RJ), is known to compose the greater part of the RJ proteins and to exist as a heterooligomer containing major royal jelly protein 1 and apisimin. However, few reports on the methods for quantifying apisin have been published. Thus, we attempted to quantify apisin using HPLC, a widely used analytical technique, as described below. Isoelectric precipitation and size-exclusion chromatography were used to obtain the purified protein, which was identified as apisin by SDS-PAGE and LC-MS analyses. The purified apisin was lyophilized and then used to generate a calibration curve to quantify apisin in RJ. The apisin content was fairly constant (i.e., 3.93 to 4.67 w/w%) in natural RJ. This study is the first to describe a simple, standardized method for quantifying apisin using HPLC and suggests that apisin can be used as a benchmark for future evaluations of RJ quality.

The physiological consequences of varied heat exposure events in adult Myzus persicae: a single prolonged exposure compared to repeated shorter exposures

The study of environmental stress tolerance in aphids has primarily been at low temperatures. In these cases, and in the rare cases of high temperature tolerance assessments, all exposures had been during a single stress event. In the present study, we examined the physiological consequences of repeated high temperature exposure with recovery periods between these stress events in Myzus persicae. We subjected individuals to either a single prolonged three hour heating event, or three one hour heating events with a recovery time of 24 h between bouts. Aphids exposed to repeated bouts of high temperatures had more glucose and higher expression of proteins and osmolyte compounds, such as glycerol, compared to the prolonged exposure group. However, aphids exposed to the repeated high temperature treatment had reduced sources of energy such as trehalose and triglyceride compounds than the prolonged exposure group. Recovery time had more physiological costs (based on production of more protein and consumption of more trehalose and triglyceride) and benefits (based on production of more osmolytes) in repeated high temperature treatments. As aphids are known to respond differently to constant versus ‘natural’ fluctuating temperature regimes, conclusions drawn from constant temperature data sets may be problematic. We suggest future experiments assessing insect responses to thermal stress incorporate a repeated stress and recovery pattern into their methodologies.

Is Trehalose an Effective Quenching Agent of Azotobacter vinelandii Mo-Nitrogenase Turnover?

H₂-evolution assays, plus EPR and FTIR spectroscopies, using CO-inhibited Azotobacter vinelandii Mo-nitrogenase have shown that the disaccharide trehalose is an effective quenching agent of enzymatic turnover and also stabilizes the reaction intermediates formed. Complete inhibition of H₂-evolution activity was achieved at 1.5 M trehalose, which compares favorably to the requirement for 10 M ethylene glycol to achieve similar inhibition. Reaction-intermediate stabilization was demonstrated by monitoring the EPR spectrum of the 'hi-CO' form of CO-inhibited N₂ase, which did not change during 1 hr after trehalose quenching. Similarly, in situ photolysis with FTIR monitoring of 'hi-CO' resulted in the same 1973 and 1681 cm^-1 signals as observed previously in ethylene glycol-quenched systems. [a] These results clearly show that 1.5 M trehalose is an effective quench and stabilization agent for Mo-N₂ase studies. Possible applications are discussed.

Gene expression analysis of overwintering mountain pine beetle larvae suggests multiple systems involved in overwintering stress, cold hardiness, and preparation for spring development

Cold-induced mortality has historically been a key aspect of mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), population control, but little is known about the molecular basis for cold tolerance in this insect. We used RNA-seq analysis to monitor gene expression patterns of mountain pine beetle larvae at four time points during their overwintering period—early-autumn, late-autumn, early-spring, and late-spring. Changing transcript profiles over the winter indicates a multipronged physiological response from larvae that is broadly characterized by gene transcripts involved in insect immune responses and detoxification during the autumn. In the spring, although transcripts associated with developmental process are present, there was no particular biological process dominating the transcriptome.

Pharmacodynamic correlations using fresh and cryopreserved tissue following use of vaginal rings containing dapivirine and/or maraviroc in a randomized, placebo controlled trial

BACKGROUND

The ex vivo challenge assay is a bio-indicator of drug efficacy and was utilized in this randomized, placebo controlled trial as one of the exploratory endpoints. Fresh and cryopreserved tissues were evaluated for human immunodeficiency virus (HIV) infection and pharmacokinetic (PK)/pharmacodynamic (PD) relationships.

METHODS

HIV-negative women used vaginal rings containing 25 mg dapivirine (DPV)/100 mg maraviroc (MVC) (n = 12), DPV only (n = 12), MVC only (n = 12), or placebo (n = 12) for 28 days. Blood plasma, cervicovaginal fluid (CVF), and cervical biopsies were collected for drug quantification and the ex vivo challenge assay; half (fresh) were exposed immediately to HIV while the other half were cryopreserved, thawed, then exposed to HIV. HIV replication was monitored by p24 enzyme-linked immunosorbent assay from culture supernatant. Data were log-transformed and analyzed by linear least squared regression, nonlinear Emax dose-response model and Satterthwaite t test.

RESULTS

HIV replication was greater in fresh compared to cryopreserved tissue (P = 0.04). DPV was detected in all compartments, while MVC was consistently detected only in CVF. Significant negative correlations between p24 and DPV levels were observed in fresh cervical tissue (P = 0.01) and CVF (P = 0.03), but not plasma. CVF MVC levels showed a significant negative correlation with p24 levels (P = 0.03); drug levels in plasma and tissue were not correlated with HIV suppression. p24 levels from cryopreserved tissue did not correlate to either drug from any compartment.

CONCLUSION

Fresh tissue replicated HIV to greater levels and defined PK/PD relationships while cryopreserved tissue did not. The ex vivo challenge assay using fresh tissue could prioritize drugs being considered for HIV prevention.

Accumulation of Poly(3-hydroxybutyrate) Helps Bacterial Cells to Survive Freezing

Accumulation of polyhydroxybutyrate (PHB) seems to be a common metabolic strategy adopted by many bacteria to cope with cold environments. This work aimed at evaluating and understanding the cryoprotective effect of PHB. At first a monomer of PHB, 3-hydroxybutyrate, was identified as a potent cryoprotectant capable of protecting model enzyme (lipase), yeast (Saccharomyces cerevisiae) and bacterial cells (Cupriavidus necator) against the adverse effects of freezing-thawing cycles. Further, the viability of the frozen-thawed PHB accumulating strain of C. necator was compared to that of the PHB non-accumulating mutant. The presence of PHB granules in cells was revealed to be a significant advantage during freezing. This might be attributed to the higher intracellular level of 3-hydroxybutyrate in PHB accumulating cells (due to the action of parallel PHB synthesis and degradation, the so-called PHB cycle), but the cryoprotective effect of PHB granules seems to be more complex. Since intracellular PHB granules retain highly flexible properties even at extremely low temperatures (observed by cryo-SEM), it can be expected that PHB granules protect cells against injury from extracellular ice. Finally, thermal analysis indicates that PHB-containing cells exhibit a higher rate of transmembrane water transport, which protects cells against the formation of intracellular ice which usually has fatal consequences.

An impediment to random walk: trehalose microenvironment drives preferential endocytic uptake of plasmonic nanoparticles

Developing effective theranostic nanoplex platforms for personalized disease treatment necessitates an understanding of and the ability to control live cell-nanoparticle interactions. However, aggregation of nanoparticles on the cell surface and their subsequent internalization is sparsely understood and adversely impact cellular recognition and viability. Here we report a facile method of precisely modulating the aggregation and uptake for silver nanoparticles without altering their surface geometry or functionalization. Exploiting the stabilization properties of trehalose, our approach enables uptake of nanoparticles while reducing aggregation on cell surface and maintaining cell viability. Electron microscopy reveals the larger utilization of endosomal structures in the trehalose-rich environment compared to the nanoparticles' "free" cytosolic diffusion patterns in the control group. Additionally, in the presence of trehalose, plasmon-enhanced Raman spectroscopy confirms the preservation of the protein structure in the vicinity of the nanoparticles reinforcing the promise of the proposed route for label-free, multiplexed intracellular monitoring.

Oral trehalose supplementation improves resistance artery endothelial function in healthy middle-aged and older adults

We hypothesized that supplementation with trehalose, a disaccharide that reverses arterial aging in mice, would improve vascular function in middle-aged and older (MA/O) men and women. Thirty-two healthy adults aged 50-77 years consumed 100 g/day of trehalose (n=15) or maltose (n=17, isocaloric control) for 12 weeks (randomized, double-blind). In subjects with Δbody mass less than 2.3kg (5 lb.), resistance artery endothelial function, assessed by forearm blood flow to brachial artery infusion of acetylcholine (FBFACh), increased ~30% with trehalose (13.3±1.0 vs. 10.5±1.1 AUC, P=0.02), but not maltose (P=0.40). This improvement in FBFACh was abolished when endothelial nitric oxide (NO) production was inhibited. Endothelium-independent dilation, assessed by FBF to sodium nitroprusside (FBFSNP), also increased ~30% with trehalose (155±13 vs. 116±12 AUC, P=0.03) but not maltose (P=0.92). Changes in FBFACh and FBFSNP with trehalose were not significant when subjects with Δbody mass ≥ 2.3kg were included. Trehalose supplementation had no effect on conduit artery endothelial function, large elastic artery stiffness or circulating markers of oxidative stress or inflammation (all P>0.1) independent of changes in body weight. Our findings demonstrate that oral trehalose improves resistance artery (microvascular) function, a major risk factor for cardiovascular diseases, in MA/O adults, possibly through increasing NO bioavailability and smooth muscle sensitivity to NO.

Proteins in binary solvents

Proteins in living organisms exist in complex aqueous solutions or embedded in membranes. In solution, proteins are surrounded by a tightly bound hydration layer, which is more ordered and less mobile than bulk water. As a consequence, water plays a major role in controlling protein structure stability, conformational flexibility, dynamics, and functionality, but it also appears that protein surface regulates the structuring of the surrounding water. The presence of cosolvents can modify the hydration layer characteristics and then the whole protein structural and dynamical properties. Because cytoplasm or biological liquids are complex solutions, the knowledge of the solvation shell characteristics in mixed solvents should be considered as a crucial step in describing biological processes at molecular level. This review reports on recent studies on the structural and thermodynamic properties of model proteins dissolved in binary solvent mixtures by small-angle neutron scattering (SANS) and differential scanning microcalorimetry (DSC) techniques. We will show that contrast variation SANS experiments allow to acquire a direct knowledge of both protein structure and protein solvation shell (in terms of low-resolution shape and solvent/cosolvent composition), while DSC experiments provide information on all the relevant thermodynamic properties. We will focus on two main points. First, an extended description of the thermodynamic model used to define the equilibria between water and cosolvent molecules in the protein solvation shell will be presented. Second, the determination of the peculiar characteristics of the protein solvation layer, which will be illustrated by considering different systems. As a conclusion, we will show that the investigation of structure and thermodynamics of proteins in binary aqueous mixtures is an important way to understand the role of hydration in protein stability and activity.

Counteraction of Trehalose on N, N-Dimethylformamide-Induced Candida rugosa Lipase Denaturation: Spectroscopic Insight and Molecular Dynamic Simulation

Candida rugosa lipase (CRL) has been widely used as a biocatalyst for non-aqueous synthesis in biotechnological applications, which, however, often suffers significant loss of activity in organic solvent. Experimental results show that trehalose could actively counteract the organic-solvent-induced protein denaturation, while the molecular mechanisms still don’t unclear. Herein, CRL was used as a model enzyme to explore the effects of trehalose on the retention of enzymatic activity upon incubation in N,N-dimethylformamide (DMF). Results showed that both catalytic activity and conformation changes of CRL influenced by DMF solvent were inhibited by trehalose in a dose-dependent fashion. The simulations further indicated that the CRL protein unfolded in binary DMF solution, but retained the native state in the ternary DMF/trehalose system. Trehalose as the second osmolyte added into binary DMF solution decreased DMF-CRL hydrogen bonds efficiently, whereas increased the intermolecular hydrogen bondings between DMF and trehalose. Thus, the origin of its denaturing effects of DMF on protein is thought to be due to the preferential exclusion of trehalose as well as the intermolecular hydrogen bondings between trehalose and DMF. These findings suggest that trehalose protect the CRL protein from DMF-induced unfolding via both indirect and direct interactions.

Engineering long shelf life multi-layer biologically active surfaces on microfluidic devices for point of care applications

Although materials and engineered surfaces are broadly utilized in creating assays and devices with wide applications in diagnostics, preservation of these immuno-functionalized surfaces on microfluidic devices remains a significant challenge to create reliable repeatable assays that would facilitate patient care in resource-constrained settings at the point-of-care (POC), where reliable electricity and refrigeration are lacking. To address this challenge, we present an innovative approach to stabilize surfaces on-chip with multiple layers of immunochemistry. The functionality of microfluidic devices using the presented method is evaluated at room temperature for up to 6-month shelf life. We integrated the preserved microfluidic devices with a lensless complementary metal oxide semiconductor (CMOS) imaging platform to count CD4⁺ T cells from a drop of unprocessed whole blood targeting applications at the POC such as HIV management and monitoring. The developed immunochemistry stabilization method can potentially be applied broadly to other diagnostic immuno-assays such as viral load measurements, chemotherapy monitoring, and biomarker detection for cancer patients at the POC.

Increased Protein Stability and Decreased Protein Turnover in the Caenorhabditis elegans Ins/IGF-1 daf-2 Mutant

In Caenorhabditis elegans, cellular proteostasis is likely essential for longevity. Autophagy has been shown to be essential for lifespan extension of daf-2 insulin/IGF mutants. Therefore, it can be hypothesized that daf-2 mutants achieve this phenotype by increasing protein turnover. However, such a mechanism would exert a substantial energy cost. By using classical ³⁵S pulse-chase labeling, we observed that protein synthesis and degradation rates are decreased in young adults of the daf-2 insulin/IGF mutants. Although reduction of protein turnover may be energetically favorable, it may lead to accumulation and aggregation of damaged proteins. As this has been shown not to be the case in daf-2 mutants, another mechanism must exist to maintain proteostasis in this strain. We observed that proteins isolated from daf-2 mutants are more soluble in acidic conditions due to increased levels of trehalose. This suggests that trehalose may decrease the potential for protein aggregation and increases proteostasis in the daf-2 mutants. We postulate that daf-2 mutants save energy by decreasing protein turnover rates and instead stabilize their proteome by trehalose.

Thiol-ene click hydrogels for therapeutic delivery

Hydrogels are of growing interest for the delivery of therapeutics to specific sites in the body. For use as a delivery vehicle, hydrophilic precursors are usually laden with bioactive moieties and then directly injected to the site of interest for in situ gel formation and controlled release dictated by precursor design. Hydrogels formed by thiol-ene click reactions are attractive for local controlled release of therapeutics owing to their rapid reaction rate and efficiency under mild aqueous conditions, enabling in situ formation of gels with tunable properties often responsive to environmental cues. Herein, we will review the wide range of applications for thiol-ene hydrogels, from the prolonged release of anti-inflammatory drugs in the spine to the release of protein-based therapeutics in response to cell-secreted enzymes, with a focus on their clinical relevance. We will also provide a brief overview of thiol-ene click chemistry and discuss the available alkene chemistries pertinent to macromolecule functionalization and hydrogel formation. These chemistries include functional groups susceptible to Michael type reactions relevant for injection and radically-mediated reactions for greater temporal control of formation at sites of interest using light. Additionally, mechanisms for the encapsulation and controlled release of therapeutic cargoes are reviewed, including i) tuning the mesh size of the hydrogel initially and temporally for cargo entrapment and release and ii) covalent tethering of the cargo with degradable linkers or affinity binding sequences to mediate release. Finally, myriad thiol-ene hydrogels and their specific applications also are discussed to give a sampling of the current and future utilization of this chemistry for delivery of therapeutics, such as small molecule drugs, peptides, and biologics.

Genetics of Mycobacterial Trehalose Metabolism

Trehalose [alpha-D-glucopyranosyl-(1→1)-alpha-D-glucopyranoside] is a highly abundant disaccharide in mycobacteria that fulfills many biological roles and has a plethora of possible metabolic fates. Trehalose is synthesized in mycobacteria de novo either from glycolytic intermediates or from alpha-glucans via two alternative routes, the OtsA-OtsB and the TreY-TreZ pathways, respectively. Intracellular trehalose can serve as an endogenous remobilizable carbon storage compound and as a biocompatible stress protectant. Furthermore, trehalose functions as the sugar core of many glycolipids with important structural or immunomodulatory functions such as the cord factor trehalose dimycolate, sulfolipids, and polyacyltrehalose. Moreover, trehalose plays a central role in the formation of the mycolic acid cell wall layer because it serves as a carrier molecule that shuttles mycolic acids in the form of the glycolipid trehalose monomycolate between the cytoplasm and the periplasm. In this process, a specific importer recycles the free trehalose that is extracellularly released as a by-product during mycolate processing via the antigen 85 complex, which might represent a specific adaptation to the intracellular lifestyle of Mycobacterium tuberculosis with limited carbohydrate availability. Finally, trehalose is converted to glycogen-like branched alpha-glucans by a four-step metabolic pathway involving the essential maltosyltransferase GlgE, which may be further processed to derivatives with intracellular or extracellular destinations such as polymethylated lipopolysaccharides or capsular alpha-glucans, respectively. In this article we summarize the current knowledge of the genetic basis of trehalose biosynthesis and metabolism in mycobacteria, the biological functions of trehalose-based molecules, and their roles in virulence of the human pathogen M. tuberculosis.

Effects of a new nutraceutical substance on clinical and molecular parameters in patients with chronic venous ulceration

Pathophysiological events involved in the onset of chronic venous ulceration (CVU) are inflammation, activation of polymorphonucleates (PMNs) and secretion of proteases such as matrix metalloproteinases (MMPs), which degrade extracellular matrix (ECM) that is a support for vascular and tissutal wall. MMPs, neutrophil gelatinase-associated lipocalin (NGAL) and inflammatory cytokines are overexpressed in CVUs and they could play a central role in pathophysiological mechanisms of skin lesion and delayed wound healing. Bioflavonoids, such as diosmin and other compounds, appear to have several provessel function activities including anti-inflammatory, antioxidant and phlebotonic effects and are widely used in the treatment of chronic venous disease (CVD)-related problems. In this article, we evaluated the effects of Axaven(®) , a new nutraceutical on both clinical and molecular parameters in patients with CVUs. During the study period, 83 patients with CVUs of both sexes were enrolled and divided into two groups: group A (treated group): 25 females and 19 males (median age is 67·7 years) received standard treatment (compression therapy and surgical correction of superficial venous incompetence) + Axaven(®) once a day for 8 months as adjunctive treatment. Group B (control group): 24 females and 15 males (median age is 65·2 years) were treated only with basic treatment according to their clinical conditions. In our study, the administration of Axaven(®) in patients with CVUs was able to decrease inflammatory cytokines, MMPs and NGAL, inducing an improvement of both symptoms with an increase of the speed of wound healing.

The gene expression level of IFN-γR1 and IFN-γR2 in a murine model treated with Toxoplasma gondii and its products

AIM

To evaluate the effect of active T. gondii tachyzoites and its products on the gene expression level of IFN-γR1 and IFN-γR2 in a murine model.

BACKGROUND

Many studies have shown that the parasite Toxoplasma gondii utilizes different mechanisms to inhibit the function of IFN-γ, but the parasite effect on the function of IFN-γR1 and IFN-γR2 is still unclear.

PATIENTS AND METHODS

Toxoplasma lysate product (TLP), excretory/secretory products (ESPs) obtained from cell free and cell culture media as well as active tachyzoites were injected separately to their respective group each consisted of 10 BALB/c mice. One control group of 10 mice received phosphate buffered saline (PBS). All of the mice were euthanized three days after the last injection and then their peritoneal leukocytes were harvested separately. The total RNA was extracted from the samples, converted to cDNA, and the gene expression level of IFN-γR1 and IFN-γR2 was assessed in all of the treated groups relative to the control one.

RESULTS

There was no significant difference between each of the treated groups relative to the control group concerning the gene expression level of IFN-γR2 (P> 0.05). Furthermore, the gene expression level of IFN-γR1 in two groups of TLP (P= 0.04) and ESP obtained from cell free medium (P= 0.008) showed a significant difference relative to the control group.

CONCLUSION

Findings of this study revealed a new aspect of host-T. gondii interaction in that this parasite is able to downregulate IFN-γR1 to reduce the IFN-γ effects on the infected cell.

Brown pigment formation in heated sugar-protein mixed suspensions containing unmodified and peptically modified whey protein concentrates

Commercial whey protein concentrate (WPC) was modified by heating the acidified protein suspensions (pH 2.0) at 80 °C for 30 min and treating with pepsin at 37 °C for 60 min. Prior to spray-drying, such modification did not change the molecular weights (MWs) of whey proteins determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). After spray-drying the modified whey protein concentrate with trehalose excipient (MWPC-TH), it was found that the α-lactalbumin (α-La) was the major protein that was further hydrolyzed the most. The reconstituted MWPC-TH contained β-lactoglobulin (β-Lg) as the major protein and small molecular weight (MW) peptides of less than 6.5 kDa. The reconstituted MWPC-TH had higher NH2 group, Trolox equivalent antioxidant capacity (TEAC), lower exposed aromatic ring and thiol (SH) contents than did the commercial WPC. Kinetic studies revealed that the addition of MWPC-TH in fructose-glycine solution was able to reduce brown pigment formation in the mixtures heated at 80 to 95 °C by increasing the activation energy (Ea) of brown pigment formation due to the retardation of fluoresced advanced glycation end product (AGEs) formation. The addition of MWPC to reducing sugar-glycine/commercial WPC was also able to lower brown pigment formation in the sterilized (121 °C, 15 min) mixed suspensions containing 0.1 M reducing sugar and 0.5-1.0 % glycine and/or commercial (P < 0.05). It was demonstrated that the modification investigated in this study selectively hydrolyzed α-La and retained β-Lg for the production of antibrowning whey protein concentrate.