Preservation of membranes in anhydrobiotic organisms: the role of trehalose

Breakdown of classical paradigms in relation to membrane structure and functions

Updates of the mosaic fluid membrane model implicitly sustain the paradigms that bilayers are closed systems conserving a state of fluidity and behaving as a dielectric slab. All of them are a consequence of disregarding water as part of the membrane structure and its essential role in the thermodynamics and kinetics of membrane response to bioeffectors. A correlation of the thermodynamic properties with the structural features of water makes possible to introduce the lipid membrane as a responsive structure due to the relaxation of water rearrangements in the kinetics of bioeffectors' interactions. This analysis concludes that the lipid membranes are open systems and, according to thermodynamic of irreversible formalism, bilayers and monolayers can be reasonable compared under controlled conditions. The inclusion of water in the complex structure makes feasible to reconsider the concept of dielectric slab and fluidity.

Mechanisms of Desiccation Tolerance: Themes and Variations in Brine Shrimp, Roundworms, and Tardigrades

Water is critical for the survival of most cells and organisms. Remarkably, a small number of multicellular animals are able to survive nearly complete drying. The phenomenon of anhydrobiosis, or life without water, has been of interest to researchers for over 300 years. In this review we discuss advances in our understanding of protectants and mechanisms of desiccation tolerance that have emerged from research in three anhydrobiotic invertebrates: brine shrimp (Artemia), roundworms (nematodes), and tardigrades (water bears). Discovery of molecular protectants that allow each of these three animals to survive drying diversifies our understanding of desiccation tolerance, and convergent themes suggest mechanisms that may offer a general model for engineering desiccation tolerance in other contexts.

Regulation of Carbohydrate Metabolism by Trehalose-6-Phosphate Synthase 3 in the Brown Planthopper, Nilaparvata lugens

Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is one of the pests that harm rice. In this paper, a new trehalose-6-phosphate synthase gene, TPS3, was identified by transcriptome sequencing and gene cloning. To explore its role in the energy metabolism of N. lugens we examined the carbohydrate contents at different stages of development, the tissue expression of TPS, and some physiological and biochemical indicators by injecting dsTPS3 and dsTPSs (a proportional mixture of dsTPS1, dsTPS2, and dsTPS3). The glucose content at the fifth instar was significantly higher than that in the fourth instar and the adult stages. The trehalose and glycogen contents before molting were higher than those after molting. TPS1, TPS2, and TPS3 were expressed in the head, leg, wing bud, and cuticle, with the highest expression in the wing bud. In addition, compared with the control group, the glucose content increased significantly at 48 h after RNA interference, and the trehalose content decreased significantly after 72 h. qRT-PCR showed that the expression level of UGPase decreased significantly at 48 h after injection, whereas GS expression increased significantly at 48 h after injecting dsTPS3. After dsTPS injection, the expression levels of PPGM2, UGPase, GP, and GS increased significantly at 72 h. After interfering with the expression of TPS3 gene alone, UGPase expression decreased significantly at 48 h, and GS expression increased significantly at 72 h. Finally, combined with the digital gene expression and pathway analysis, 1439 and 1346 genes were upregulated, and 2127 and 1927 genes were downregulated in the dsTPS3 and dsTPSs groups, respectively. The function of most differential genes was concentrated in sugar metabolism, lipid metabolism, and amino acid metabolism. The results indicated that TPS3 plays a key role in the energy metabolism of N. lugens and confirmed that TPS3 is a feasible target gene for RNA interference in N. lugens. Simultaneously, they provide a theoretical basis for the development and utilization of TPS3 to control pests.

Cryoprotective enhancing effect of very low concentration of trehalose on the functions of primary rat hepatocytes

Introduction

Cells have various applications in biomedical research. Cryopreservation is a cell-preservation technique that provides cells for such applications. After cryopreservation, sensitive cells, such as primary hepatocytes, suffer from low viability due to the physical damage caused by ice crystals, highlighting the need for better methods of cryopreservation to improve cell viability. Given the importance of effectively suppressing ice crystal formation to protect cellular structure, trehalose has attracted attention as cryoprotectant based on its ability to inhibit ice crystal formation; however, trehalose induces osmotic stress. Therefore, to establish a cell-cryopreservation technique, it is necessary to provide an optimal balance between the protective and damaging effects of trehalose.

Methods

In this study, we evaluated the effects of osmotic stress and ice crystal formation on the viability and function of primary rat hepatocytes at wide range of trehalose concentration.

Results

There was no osmotic stress at very low concentrations (2.6 μM) of trehalose, and 2.6 μM trehalose drives the formation of finer ice crystals, which are less damaging to the cell membrane. Furthermore, we found that the number of viable hepatocytes after cryopreservation were 70% higher under the 2.6 μM trehalose-supplemented conditions than under the dimethyl sulfoxide-supplemented conditions. Moreover, non-cryopreserved cells and cells cryopreserved with trehalose showed comparable intracellular dehydrogenase activity.

Conclusions

We showed that trehalose at very low concentrations (2.6 μM) improved dramatically viability and liver function of hepatocyte after cryopreservation.

•

Very low concentration of trehalose could suppress ice crystal formation and protect cell structure.

•

There was a correlation between osmotic pressure of trehalose and hepatocytes viability.

•

Very low concentration of trehalose improved viability and liver function of hepatocyte after cryopreservation.

Review of non-permeating cryoprotectants as supplements for vitrification of mammalian tissues

Vitrification of mammalian tissues is important in the areas of human assisted reproduction, animal reproduction, and regenerative medicine. Non-permeating cryoprotectants (CPAs), particularly sucrose, are increasingly used in conjunction with permeating CPAs for vitrification of mammalian tissues. Combining non-permeating and permeating CPAs was found to further improve post-thaw viability and functionalities of vitrified mammalian tissues, showing the potential applications of such tissues in various clinical and veterinary settings. With the rising demand for the use of non-permeating CPAs in vitrification of mammalian tissues, there is a strong need for a timely and comprehensive review on the supplemental effects of non-permeating CPAs toward vitrification outcomes of mammalian tissues. In this review, we first discuss the roles of non-permeating CPAs including sugars and high molecular weight polymers in vitrification. We then summarize the supplemental effects of non-permeating CPAs on viability and functionalities of mammalian embryos, and ovarian, testicular, articular cartilage, tracheal, and kidney tissues following vitrification. Lastly, challenges associated with the use of non-permeating CPAs in vitrification of mammalian tissues are briefly discussed.

The Modulation of Trehalose Metabolism by 20-Hydroxyecdysone in Antheraea pernyi (Lepidoptera: Saturniidae) During its Diapause Termination and Post-Termination Period

Trehalose plays a crucial role in the diapause process of many insects, serving as an energy source and a stress protectant. Trehalose accumulation has been reported in diapause pupae of Antheraea pernyi; however, trehalose metabolic regulatory mechanisms associated with diapause termination remain unclear. Here, we showed that the enhanced trehalose catabolism was associated with an increase in endogenous 20-hydroxyecdysone (20E) in hemolymph of A. pernyi pupae during their diapause termination and posttermination period. Injection of 20E increased the mRNA level of trehalase 1A (ApTre-1A) and trehalase 2 (ApTre-2) of A. pernyi diapause pupae in a dose-dependent manner but did not affect the mRNA level of trehalase 1B (ApTre-1B). Meanwhile, exogenous 20E increased the enzyme activities of soluble and membrane-bound trehalase, leading to a decline in hemolymph trehalose. Conversely, the expression of ApTre-1A and ApTre-2 were down-regulated after the ecdysone receptor gene (ApEcRB1) was silenced by RNA interference or by injection of an ecdysone receptor antagonist cucurbitacin B (CucB), which inhibits the 20E pathway. Moreover, CucB treatment delayed adult emergence, which suggests that ApEcRB1 might be involved in regulating pupal-adult development of A. pernyi by mediating ApTre-1A and ApTre-2 expressions. This study provides an overview of the changes in the expression and activity of different trehalase enzymes in A. pernyi in response to 20E, confirming the important role of 20E in controlling trehalose catabolism during A. pernyi diapause termination and posttermination period.

Packing and dynamics of a protein solution approaching the jammed state

The packing of proteins and their collective behavior in crowded media is crucial for the understanding of biological processes. Here we study the structural and dynamical evolution of solutions of the globular protein bovine serum albumin with increasing concentration via drying using small angle X-ray scattering and dynamic light scattering. We probe an evolving correlation peak on the scattering profile, corresponding to the inter-protein distance, ξ, which decreases following a power law of the protein volume fraction, φ. The rate of decrease in ξ becomes faster above a protein concentration of ∼200 mg ml-1 (φ = 0.15). The power law exponent changes from 0.33, which is typical of colloidal or protein solutions, to 0.41. During the entire drying process, we observe the development and the growth of two-step relaxation dynamics with increasing φ as revealed by dynamic light scattering. We find three different regimes of the dependence of ξ as a function of φ. In the dilute regime (φ < 0.22), protein molecules are far apart from each other compared to their size. In this case, the dynamics mainly corresponds to Brownian motion. At an intermediate concentration (0.22 < φ < 0.47), inter-protein distances become comparable to the size of protein molecules, leading to a preferential orientation of the ellipsoidal protein molecules along with a possible deformation. In this regime, the dynamics shows two distinct relaxation times. At a very high concentration (φ > 0.47), the system reaches a jammed state. Subsequently, the secondary relaxation time in this state becomes extremely slow. In this state, the protein molecules have approximately one hydration layer. This study contributes to the understanding of protein molecular packing in crowded environments and the phenomenon of density-driven jamming for soft matter systems.

Characteristics, dynamics and mechanisms of actions of some major stress-induced biomacromolecules; addressing Artemia as an excellent biological model

Stress tolerance is one of the most prominent and interesting topics in biology since many macro- and micro-adaptations have evolved in resistant organisms that are worth studying. When it comes to confronting various environmental stressors, the extremophile Artemia is unrivaled in the animal kingdom. In the present review, the evolved molecular and cellular basis of stress tolerance in resistant biological systems are described, focusing on Artemia cyst as an excellent biological model. The main purpose of the review is to discuss how the structure and physicochemical characteristics of protective factors such as late embryogenesis abundant proteins (LEAPs), small heat shock proteins (sHSPs) and trehalose are related to their functions and by which mechanisms, they exert their functions. In addition, some metabolic depressors in Artemia encysted embryos are also mentioned, indirectly playing important roles in stress tolerance. Importantly, a great deal of attention is given to the LEAPs, exhibiting distinctive folding behaviors and mechanisms of actions. For instance, molecular shield function, chaperone-like activity, moonlighting property, sponging and snorkeling capabilities of the LEAPs are delineated here. Moreover, the molecular interplay between some of these factors is mentioned, leading to their synergistic effects. Interestingly, Artemia life cycle adapts to environmental conditions. Diapause is the defense mode of this life cycle, safeguarding Artemia encysted embryos against various environmental stressors. Communicated by Ramaswamy H. Sarma.

Combined metabolome and transcriptome analysis reveals key components of complete desiccation tolerance in an anhydrobiotic insect

Anhydrobiosis is a reversible ametabolic state that occurs in response to severe desiccation. The largest anhydrobiotic animal known is the larva of the African chironomid Polypedilum vanderplanki. Here, we investigated how the metabolism of larvae changes during the desiccation–rehydration cycle and how simple biochemical processes determine viability of the chironomid. Major findings suggest that, in addition to its known anhydroprotectant role, trehalose acts as a major source of energy for rehydration. Citrate and adenosine monophosphate, accumulated in the dry state, allow rapid resumption of metabolism during the recovery phase. Finally, metabolic waste is stored as stable or nontoxic compounds such as allantoin, xanthurenic acid, or ophthalmic acid that may also act as antioxidants.

Some organisms have evolved a survival strategy to withstand severe dehydration in an ametabolic state, called anhydrobiosis. The only known example of anhydrobiosis among insects is observed in larvae of the chironomid Polypedilum vanderplanki. Recent studies have led to a better understanding of the molecular mechanisms underlying anhydrobiosis and the action of specific protective proteins. However, gene regulation alone cannot explain the rapid biochemical reactions and independent metabolic changes that are expected to sustain anhydrobiosis. For this reason, we conducted a comprehensive comparative metabolome–transcriptome analysis in the larvae. We showed that anhydrobiotic larvae adopt a unique metabolic strategy to cope with complete desiccation and, in particular, to allow recovery after rehydration. We argue that trehalose, previously known for its anhydroprotective properties, plays additional vital roles, providing both the principal source of energy and also the restoration of antioxidant potential via the pentose phosphate pathway during the early stages of rehydration. Thus, larval viability might be directly dependent on the total amount of carbohydrate (glycogen and trehalose). Furthermore, in the anhydrobiotic state, energy is stored as accumulated citrate and adenosine monophosphate, allowing rapid reactivation of the citric acid cycle and mitochondrial activity immediately after rehydration, before glycolysis is fully functional. Other specific adaptations to desiccation include potential antioxidants (e.g., ophthalmic acid) and measures to avoid the accumulation of toxic waste metabolites by converting these to stable and inert counterparts (e.g., xanthurenic acid and allantoin). Finally, we confirmed that these metabolic adaptations correlate with unique organization and expression of the corresponding enzyme genes.

Stabilizing Enzymes within Polymersomes by Coencapsulation of Trehalose

Enzymes are essential biocatalysts and very attractive as therapeutics. However, their functionality is strictly related to their stability, which is significantly affected by the environmental changes occurring during their usage or long-term storage. Therefore, maintaining the activity of enzymes is essential when they are exposed to high temperature during usage or when they are stored for extended periods of time. Here, we stabilize and protect enzymes by coencapsulating them with trehalose into polymersomes. The anhydrobiotic disaccharide preserved up to about 81% of the enzyme's original activity when laccase/trehalose-loaded nanoreactors were kept desiccated for 2 months at room temperature and 75% of its activity when heated at 50 °C for 3 weeks. Moreover, the applicability of laccase/trehalose-loaded nanoreactors as catalysts for bleaching of the textile dyes orange G, toluidine blue O, and indigo was proven. Our results demonstrate the advantages of coencapsulating trehalose within polymersomes to stabilize enzymes in dehydrated state for extended periods of time, preserving their activity even when heated to elevated temperature.

Permeabilized TreS-Expressing Bacillus subtilis Cells Decorated with Glucose Isomerase and a Shell of ZIF-8 as a Reusable Biocatalyst for the Coproduction of Trehalose and Fructose

Metal-organic frameworks (MOFs) are a class of porous materials with versatile properties. In this study, ZIF-8 was employed to establish a two-enzyme system by encapsulating permeabilized Bacillus subtilis cells coated with glucose isomerase. B. subtilis was constructed by introducing the shuttle plasmid PMA5 associated with the overexpression of trehalose synthase. Using this two-enzyme system, trehalose was produced by trehalose synthase and the byproduct glucose was converted to fructose with the help of glucose isomerase. The decrease in glucose production not only relieved the inhibition of the entire reaction chain but also increased the final yield of trehalose. The highest trehalose production rate reached 67.7% and remained above 50% after 20 batches. In addition, the toxicity of the ZIF-8 coating for B. subtilis was investigated by fluorescence microscopy and was found to be negligible. By simulating an extreme environment, the ZIF-8 coating was demonstrated to have a protective effect on the cells and enzymes. This study provides a theoretical basis for the application of MOFs in the immobilization of microorganisms and enzymes.

Common Functions of Disordered Proteins across Evolutionary Distant Organisms

Intrinsically disordered proteins and regions typically lack a well-defined structure and thus fall outside the scope of the classic sequence–structure–function relationship. Hence, classic sequence- or structure-based bioinformatic approaches are often not well suited to identify homology or predict the function of unknown intrinsically disordered proteins. Here, we give selected examples of intrinsic disorder in plant proteins and present how protein function is shared, altered or distinct in evolutionary distant organisms. Furthermore, we explore how examining the specific role of disorder across different phyla can provide a better understanding of the common features that protein disorder contributes to the respective biological mechanism.

Sugars and Sweeteners: Structure, Properties and In Silico Modeling

Several studies report the effects of excessive use of sugars and sweeteners in the diet. These include obesity, cardiac diseases, diabetes, and even lymphomas, leukemias, cancers of the bladder and brain, chronic fatigue syndrome, Parkinson's disease, Alzheimer's disease, multiple sclerosis, autism, and systemic lupus. On the other hand, each sugar and sweetener has a distinct metabolic assimilation process, and its chemical structure plays an important role in this process. Several scientific papers present the biological effects of the sugars and sweeteners in relation to their chemical structure. One important issue dealing with the sugars is the degree of similarity in their structures, focusing mostly on optical isomerism. Finding and developing new sugars and sweeteners with desired properties is an emerging research area, in which in silico approaches play an important role.

Simple sugars shape giant vesicles into multispheres with many membrane necks

Simple sugars such as glucose and sucrose are ubiquitous in all organisms. One remarkable property of these small solutes is their ability to protect biomembranes against dehydration damage. This property, which reflects the underlying sugar-lipid interactions, has been intensely studied for lipid bilayers interacting with a single sugar at low hydration. Here, we use giant vesicles to investigate fully hydrated lipid membranes in contact with two sugars, glucose and sucrose. The vesicles were osmotically balanced, with the same total sugar concentration in the interior and exterior aqueous solutions. However, the two solutions differed in their composition: the interior solution contained only sucrose whereas the exterior one contained primarily glucose. This sugar asymmetry generated a striking variety of multispherical or "multi-balloon" vesicle shapes. Each multisphere involved only a single membrane that formed several spherical segments, which were connected by narrow, hourglass-shaped membrane necks. These morphologies revealed that the sugar-lipid interactions generated a significant spontaneous curvature with a magnitude of about 1 μm^-1. Such a spontaneous curvature can be generated both by depletion and by adsorption layers of the sugar molecules arising from effectively repulsive and attractive sugar-lipid interactions. All multispherical shapes are stable over a wide range of parameters, with a substantial overlap between the different stability regimes, reflecting the rugged free energy landscape in shape space. One challenge for future studies is to identify pathways within this landscape that allow us to open and close the membrane necks of these shapes in a controlled and reliable manner. We will then be able to apply these multispheres as metamorphic chambers for chemical reactions and nanoparticle growth.

Molecular docking studies of phytochemicals against trehalose–6–phosphate phosphatases of pathogenic microbes

Background

Many of the pathogenic microbes use trehalose–6–phosphate phosphatase (TPP) enzymes for biosynthesis of sugar trehalose from trehalose–6–phosphate (T6P) in their pathway of infection and proliferation. Therefore, the present work is an approach to design new generation candidate drugs to inhibit TPP through in silico methods.

Results

Blast P and Clustal Omega phylogenetic analysis of TPP sequences were done for 12 organisms that indicate and confirm the presence of three conserved active site regions of known TPPs. Docking studies of 3D model of TPP with 17 phytochemicals revealed most of them have good binding affinity to an enzyme with rutin exhibiting highest affinity (Binding energy of − 7 kcal/mole). It has been found that during docking, phytochemical leads bind to active site region 3 of TPP sequences which coordinates Mg2+ and essential for catalysis.

Conclusions

Binding poses and distance measurement of TPP-phytochemical complexes of rutin, carpaine, stigmasterol, β-caryophyllene, and α-eudesmol reveals that the lead phytochemicals were in close proximity with most of the active site amino acids of region 3 (distance range from 1.796 to 2.747 Ao). This confirms the tight binding between enzyme and leads which may pave way for the discovery of new generation drugs against TPP producing pathogenic microbes to manage diseases.

Compatible solutes adaptive alterations in Arthrobacter simplex during exposure to ethanol, and the effect of trehalose on the stress resistance and biotransformation performance

Ethanol-tolerant Arthrobacter simplex is desirable since ethanol facilitates hydrophobic substrates dissolution on an industrial scale. Herein, alterations in compatible solutes were investigated under ethanol stress. The results showed that the amount of trehalose and glycerol increased while that of glutamate and proline decreased. The trehalose protectant role was verified and its concentration was positively related to the degree of cell tolerance. otsA, otsB and treS, three trehalose biosynthesis genes in A. simplex, also enhanced Escherichia coli stress tolerance, but the increased tolerance was dependent on the type and level of the stress. A. simplex strains accumulating trehalose showed a higher productivity in systems containing more ethanol and substrate because of better viability. The underlying mechanisms of trehalose were involved in better cell integrity, higher membrane stability, stronger reactive oxygen species scavenging capacity and higher energy level. Therefore, trehalose was a general protectant and the upregulation of its biosynthesis by genetic modification enhanced cell stress tolerance, consequently promoted productivity.

Simple Syntheses of New Pegylated Trehalose Derivatives as a Chemical Tool for Potential Evaluation of Cryoprotectant Effects on Cell Membrane

In our work, we developed the synthesis of new polyfunctional pegylated trehalose derivatives and evaluated their cryoprotective effect using flow cytometry. We showed that new compounds (modified trehaloses) bound to appropriate extracellular polymeric cryoprotectants could be helpful as a chemical tool for the evaluation of their potential toxic cell membrane influences. Our aim was to form a chemical tool for the evaluation of cryoprotectant cell membrane influences, which are still not easily predicted during the freezing/thawing process. We combined two basic cryoprotectants: polyethyleneglycols (PEGs) and trehalose in the new chemical compounds—pegylated trehalose hybrids. If PEG and trehalose are chemically bound and trehalose is adsorbed on the cell surface PEGs molecules which are, due to the chemical bonding with trehalose, close to the cell surface, can remove the cell surface hydration layer which destabilizes the cell membrane. This was confirmed by the comparison of new material, PEG, trehalose, and their mixture cryoprotective capabilities.

Trehalose-Based Polyethers for Cryopreservation and Three-Dimensional Cell Scaffolds

The capability to slow ice growth and recrystallization is compulsory in the cryopreservation of cells and tissues to avoid injuries associated with the physical and chemical responses of freezing and thawing. Cryoprotective agents (CPAs) have been used to restrain cryoinjury and improve cell survival, but some of these compounds pose greater risks for the clinical application of cryopreserved cells due to their inherent toxicity. Trehalose is known for its unique physicochemical properties and its interaction with the phospholipids of the plasma membrane, which can reduce cell osmotic stress and stabilized the cryopreserved cells. Nonetheless, there has been a shortage of relevant studies on the synthesis of trehalose-based CPAs. We hereby report the synthesis and evaluation of a trehalose-based polymer and hydrogel and its use as a cryoprotectant and three-dimensional (3D) cell scaffold for cell encapsulation and organoid production. In vitro cytotoxicity studies with the trehalose-based polymers (poly(Tre-ECH)) demonstrated biocompatibility up to 100 mg/mL. High post-thaw cell membrane integrity and post-thaw cell plating efficiencies were achieved after 24 h of incubation with skin fibroblast, HeLa (cervical), and PC3 (prostate) cancer cell lines under both controlled-rate and ultrarapid freezing protocols. Differential scanning calorimetry and a splat cooling assay for the determination of ice recrystallization inhibition activity corroborated the unique properties of these trehalose-based polyethers as cryoprotectants. Furthermore, the ability to form hydrogels as 3D cell scaffolds encourages the use of these novel polymers in the development of cell organoids and cryopreservation platforms.

Dry biobanking as a conservation tool in the Anthropocene

Species are going extinct at an alarming rate, termed by some as the sixth mass extinction event in the history of Earth. Many are the causes for this but in the end, all converge to one entity - humans. Since we are the cause, we also hold the key to making the change. Any change, however, will take time, and for some species this could be too long. While working on possible solutions, we also have the responsibility to buy time for those species on the verge of extinction. Genome resource banks, in the form of cryobanks, where samples are maintained under liquid nitrogen, are already in existence but they come with a host of drawbacks. Biomimicry - innovation inspired by Nature, has been a huge source for ideas. Searching methods that Nature utilizes to preserve biological systems for extended periods of time, we realize that drying rather than freezing is the method of choice. We thus argue here in favor of preserving at least part of the samples from critically endangered species in dry biobanks, a much safer, cost-effective, biobanking approach.

A bioinspired approach to engineer seed microenvironment to boost germination and mitigate soil salinity

In a world that strives to accommodate population growth and climate pattern changes, there is a compelling need to develop new technologies to enhance agricultural output while minimizing inputs and mitigating their effects on the environment. In this study, we describe a biomaterial-based approach to engineer the microenvironment of seeds through the preservation and delivery of plant growth promoting rhizobacteria (PGPRs) that are able to fix nitrogen and mitigate soil salinity. PGPRs are encapsulated in silk–trehalose (ST) coatings that achieve bacterial preservation and delivery upon sowing. The biomaterial choice is inspired by a recent finding that a combination of proteins and disaccharides is key for anhydrobiosis. This simple technology is effective to boost seed germination and mitigate soil salinity.

Human population growth, soil degradation, and agrochemical misuse are significant challenges that agriculture must face in the upcoming decades as it pertains to global food production. Seed enhancement technologies will play a pivotal role in supporting food security by enabling germination of seeds in degraded environments, reducing seed germination time, and boosting crop yields. So far, a great effort has been pursued in designing plants that can adapt to different environments and germinate in the presence of abiotic stressors, such as soil salinity, heat, and drought. The technology proposed here seeks a different goal: To engineer the microenvironment of seeds by encapsulation, preservation, and precise delivery of biofertilizers that can boost seed germination and mitigate abiotic stressors. In particular, we developed a biomaterial based on silk fibroin (S) and trehalose that can be mixed with rhizobacteria and applied on the surface of seeds, retrofitting currently used techniques for seed coating, i.e., dip coating or spray drying. A micrometer thick transparent robust coating is formed by material assembly. The combination of a polymorphic protein as S and of a disaccharide used by living systems to tolerate abiotic stressors provides a beneficial environment for the survival of nonspore forming rhizobacteria outside the soil and in anhydrous conditions. Using Rhizobium tropici CIAT 899 and Phaseolus vulgaris as working models, we demonstrated that rhizobacteria delivered in the soil after coating dissolution infect seedlings’ roots, form root nodules, enhance yield, boost germination, and mitigate soil salinity.

Osmoprotection in plants under abiotic stresses: new insights into a classical phenomenon

Plant osmoprotectants protect against abiotic stresses. Introgression of osmoprotectant genes into crop plants via genetic engineering is an important strategy in developing more productive plants. Plants employ adaptive mechanisms to survive various abiotic stresses. One mechanism, the osmoprotection system, utilizes various groups of low molecular weight compounds, collectively known as osmoprotectants, to mitigate the negative effect of abiotic stresses. Osmoprotectants may include amino acids, polyamines, quaternary ammonium compounds and sugars. These nontoxic compounds stabilize cellular structures and enzymes, act as metabolic signals, and scavenge reactive oxygen species produced under stressful conditions. The advent of recent drastic fluctuations in the global climate necessitates the development of plants better adapted to abiotic stresses. The introgression of genes related to osmoprotectant biosynthesis from one plant to another by genetic engineering is a unique strategy bypassing laborious conventional and classical breeding programs. Herein, we review recent literature related to osmoprotectants and transgenic plants engineered with specific osmoprotectant properties.

A computational approach to get insights into multiple faces of additives in modulation of protein aggregation pathways

An enormous population worldwide is presently confronted with debilitating neurodegenerative diseases. The etiology of the disease is connected to protein aggregation and the events involved therein. Thus, a complete understanding of an inhibitor at different stages in the process is imperative for the formulation of a drug molecule. This review presents a detailed summary of the current status of different cosolvents. It further develops how the complex aggregation pathway can be simplified into three steps common to all proteins and the way computer simulations can be exploited to gain insights into the ways by which known inhibitors can affect all these stages. Computation of theoretical parameters in this regard and their correlation with experimental techniques is accentuated. In addition to providing an outline of the scope of different additives, this review showcases the way by which the problem of analyzing an effect of an additive can be addressed effectively via MD simulations.

Effects of Pulsed Electric Field-Assisted Osmotic Dehydration and Edible Coating on the Recovery of Anthocyanins from In Vitro Digested Berries

Berry fruits, such as strawberries and blueberries, are rich sources of anthocyanins. Several studies have been made on the impact of non-thermal treatments on safety, shelf-life and nutritional characteristics of such products, but the effects of these processes on anthocyanin stability during digestion in the gastrointestinal tract are still not completely clear. The aim of this study was to assess the recovery of anthocyanins after simulated gastrointestinal digestion of (1) strawberry samples, pre-treated with pulsed electric field (PEF) at 100 or 200 V·cm^-1, prior to osmotic dehydration (OD), and (2) blueberry samples coated with chitosan and procyanidin. After digestion, a significantly higher content of cyanidin-3-O-glucoside and malvidin-3-O-glucoside was quantified by LC-MS/MS in processed strawberry and blueberry samples, compared with the controls. The highest recovery of cyanidin-3-O-glucoside was detected in digested strawberry samples osmotically dehydrated with trehalose. The recovery of malvidin-3-O-glucoside was highest in digested blueberries coated with chitosan and stored for 14 days, compared with untreated samples or samples coated with chitosan and procyanidin. Our study shows the potential of mild PEF treatments combined with OD, or the use of edible coating, to obtain shelf-stable products without substantially affecting the composition or the stability of anthocyanins during digestion in the upper gastrointestinal tract.

Comparative proteomics of stenotopic caddisfly Crunoecia irrorata identifies acclimation strategies to warming

Species' ecological preferences are often deduced from habitat characteristics thought to represent more or less optimal conditions for physiological functioning. Evolution has led to stenotopic and eurytopic species, the former having decreased niche breadths and lower tolerances to environmental variability. Species inhabiting freshwater springs are often described as being stenotopic specialists, adapted to the stable thermal conditions found in these habitats. Whether due to past local adaptation these species have evolved or have lost intra-generational adaptive mechanisms to cope with increasing thermal variability has, to our knowledge, never been investigated. By studying how the proteome of a stenotopic species changes as a result of increasing temperatures, we investigate if the absence or attenuation of molecular mechanisms is indicative of local adaptation to freshwater springs. An understanding of compensatory mechanisms is especially relevant as spring specialists will experience thermal conditions beyond their physiological limits due to climate change. In this study, the stenotopic species Crunoecia irrorata (Trichoptera: Lepidostomatidae, Curtis 1834) was acclimated to 10, 15 and 20°C for 168 hr. We constructed a homology-based database and via liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based shotgun proteomics identified 1,358 proteins. Differentially abundant proteins and protein norms of reaction revealed candidate proteins and molecular mechanisms facilitating compensatory responses such as trehalose metabolism, tracheal system alteration and heat-shock protein regulation. A species-specific understanding of compensatory physiologies challenges the characterization of species as having narrow tolerances to environmental variability if that characterization is based on occurrences and habitat characteristics alone.

Contrast enhanced ultrasound imaging by nature-inspired ultrastable echogenic nanobubbles

Advancement of ultrasound molecular imaging applications requires not only a reduction in size of the ultrasound contrast agents (UCAs) but also a significant improvement in the in vivo stability of the shell-stabilized gas bubble. The transition from first generation to second generation UCAs was marked by an advancement in stability as air was replaced by a hydrophobic gas, such as perfluoropropane and sulfur hexafluoride. Further improvement can be realized by focusing on how well the UCAs shell can retain the encapsulated gas under extreme mechanical deformations. Here we report the next generation of UCAs for which we engineered the shell structure to impart much better stability under repeated prolonged oscillation due to ultrasound, and large changes in shear and turbulence as it circulates within the body. By adapting an architecture with two layers of contrasting elastic properties similar to bacterial cell envelopes, our ultrastable nanobubbles (NBs) withstand continuous in vitro exposure to ultrasound with minimal signal decay and have a significant delay on the onset of in vivo signal decay in kidney, liver, and tumor. Development of ultrastable NBs can potentially expand the role of ultrasound in molecular imaging, theranostics, and drug delivery.

Three novel trehalase genes from Harmonia axyridis (Coleoptera: Coccinellidae): cloning and regulation in response to rapid cold and re-warming

Trehalose is the main blood sugar in insects. To study the function of trehalase during exposure to low temperatures, three other novel cDNAs of trehalase were cloned from Harmonia axyridis by transcriptome sequencing and rapid amplification of cDNA ends. One of the cloned cDNAs encoded a soluble trehalase, the second trehalase cDNA encoded a transmembrane-like domain, and the third cDNA encoded a membrane-bound protein. Therefore, these cDNAs were, respectively, named HaTreh1-5, HaTreh2-like, and HaTreh2. HaTreh1-5, HaTreh2-like, and HaTreh2 cDNAs encoded proteins containing 586, 553, and 633 amino acids with predicted masses of approximately 69.47, 63.46, and 73.66 kDa, and pIs of 9.20, 5.52, and 6.31, respectively. All three novel trehalases contained signal motifs "PGGINKESYYLDSY", "QWDYPNAWPP", and a highly conserved glycine-rich (GGGGEY) region. The expression levels of HaTreh1-5 and HaTreh2 mRNAs were high during adult stages, whereas HaTreh2-like was expressed in low amounts in the fourth larval stage. The results showed that the activity of membrane-bound trehalases decreased from 25 to 10 °C and from 5 to - 5 °C during cooling. The results also revealed a decreasing trend in expression of the three HaTreh mRNAs during the cooling treatment, and an initial decrease followed by an increase during the process of re-warming.

Desiccation tolerance: an unusual window into stress biology

Climate change has accentuated the importance of understanding how organisms respond to stresses imposed by changes to their environment, like water availability. Unusual organisms, called anhydrobiotes, can survive loss of almost all intracellular water. Desiccation tolerance of anhydrobiotes provides an unusual window to study the stresses and stress response imposed by water loss. Because of the myriad of stresses that could be induced by water loss, desiccation tolerance seemed likely to require many established stress effectors. The sugar trehalose and hydrophilins (small intrinsically disordered proteins) had also been proposed as stress effectors against desiccation because they were found in nearly all anhydrobiotes, and could mitigate desiccation-induced damage to model proteins and membranes in vitro. Here, we summarize in vivo studies of desiccation tolerance in worms, yeast, and tardigrades. These studies demonstrate the remarkable potency of trehalose and a subset of hydrophilins as the major stress effectors of desiccation tolerance. They act, at least in part, by limiting in vivo protein aggregation and loss of membrane integrity. The apparent specialization of individual hydrophilins for desiccation tolerance suggests that other hydrophilins may have distinct roles in mitigating additional cellular stresses, thereby defining a potentially new functionally diverse set of stress effectors.

DPPC Bilayers in Solutions of High Sucrose Content

The properties of lipid bilayers in sucrose solutions have been intensely scrutinized over recent decades because of the importance of sugars in the field of biopreservation. However, a consensus has not yet been formed on the mechanisms of sugar-lipid interaction. Here, we present a study on the effect of sucrose on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine bilayers that combines calorimetry, spectral fluorimetry, and optical microscopy. Intriguingly, our results show a significant decrease in the transition enthalpy but only a minor shift in the transition temperature. Our observations can be quantitatively accounted for by a thermodynamic model that assumes partial delayed melting induced by sucrose adsorption at the membrane interface.

New Approaches to Cryopreservation of Cells, Tissues, and Organs

In this concept article, we outline a variety of new approaches that have been conceived to address some of the remaining challenges for developing improved methods of biopreservation. This recognizes a true renaissance and variety of complimentary, high-potential approaches leveraging inspiration by nature, nanotechnology, the thermodynamics of pressure, and several other key fields. Development of an organ and tissue supply chain that can meet the healthcare demands of the 21st century means overcoming twin challenges of (1) having enough of these lifesaving resources and (2) having the means to store and transport them for a variety of applications. Each has distinct but overlapping logistical limitations affecting transplantation, regenerative medicine, and drug discovery, with challenges shared among major areas of biomedicine including tissue engineering, trauma care, transfusion medicine, and biomedical research. There are several approaches to biopreservation, the optimum choice of which is dictated by the nature and complexity of the tissue and the required length of storage. Short-term hypothermic storage at temperatures a few degrees above the freezing point has provided the basis for nearly all methods of preserving tissues and solid organs that, to date, have proved refractory to cryopreservation techniques successfully developed for single-cell systems. In essence, these short-term techniques have been based on designing solutions for cellular protection against the effects of warm and cold ischemia and basically rely upon the protective effects of reduced temperatures brought about by Arrhenius kinetics of chemical reactions. However, further optimization of such preservation strategies is now seen to be restricted. Long-term preservation calls for much lower temperatures and requires the tissue to withstand the rigors of heat and mass transfer during protocols designed to optimize cooling and warming in the presence of cryoprotective agents. It is now accepted that with current methods of cryopreservation, uncontrolled ice formation in structured tissues and organs at subzero temperatures is the single most critical factor that severely restricts the extent to which tissues can survive procedures involving freezing and thawing. In recent years, this major problem has been effectively circumvented in some tissues by using ice-free cryopreservation techniques based upon vitrification. Nevertheless, despite these promising advances there remain several recognized hurdles to be overcome before deep-subzero cryopreservation, either by classic freezing and thawing or by vitrification, can provide the much-needed means for biobanking complex tissues and organs for extended periods of weeks, months, or even years. In many cases, the approaches outlined here, including new underexplored paradigms of high-subzero preservation, are novel and inspired by mechanisms of freeze tolerance, or freeze avoidance, in nature. Others apply new bioengineering techniques such as nanotechnology, isochoric pressure preservation, and non-Newtonian fluids to circumvent currently intractable problems in cryopreservation.

The trehalose protective mechanism during thermal stress in Saccharomyces cerevisiae: the roles of Ath1 and Agt1

Trehalose on both sides of the bilayer is a requirement for full protection of membranes against stress. It was not known yet how trehalose, synthesized in the cytosol when dividing Saccharomyces cerevisiae cells are shifted from 28°C to 40°C, is transported to the outside and degraded when cells return to 28°C. According to our results, the lack of Agt1, a trehalose transporter, although had not affected trehalose synthesis, reduced cell tolerance to 51°C and increased lipid peroxidation. The damage was reversed when external trehalose was added during 40°C adaptation, confirming that the reason for the agt1Δ sensitivity is the absence of trehalose at the outside of the lipid bilayer. The 40-28°C condition caused cytosolic trehalase (Nth1) activation, reducing intracellular trehalose and, consequently, the survival rates after 51°C. Although lower than nth1Δ strain, cells deficient in acid trehalase (ath1Δ)  maintained increased trehalose levels after 40°C-28°C shift, which conferred protection against 51°C. Both Ath1 and Agt1 were found into vesicles near to plasma membrane in response to stress. This suggests that Agt1 containing vesicles would fuse with the membrane under 40°C to transport part of the cytosolic trehalose to the outside. By a similar mechanism, Ath1 would reach the cell surface to hydrolyze the external trehalose but only when the stress would be over. Corroborating this conclusion, Ath1 activity in soluble cell-free extracts increased after 40°C adaptation but decreased when cells returned to 28°C. During 40°C, Ath1 is confined into vesicles, avoiding the cleavage of the outside trehalose.

Allosteric activation of yeast enzyme neutral trehalase by calcium and 14-3-3 protein

Neutral trehalase 1 (Nth1) from Saccharomyces cerevisiae catalyzes disaccharide trehalose hydrolysis and helps yeast to survive adverse conditions, such as heat shock, starvation or oxidative stress. 14-3-3 proteins, master regulators of hundreds of partner proteins, participate in many key cellular processes. Nth1 is activated by phosphorylation followed by 14-3-3 protein (Bmh) binding. The activation mechanism is also potentiated by Ca(2+) binding within the EF-hand-like motif. This review summarizes the current knowledge about trehalases and the molecular and structural basis of Nth1 activation. The crystal structure of fully active Nth1 bound to 14-3-3 protein provided the first high-resolution view of a trehalase from a eukaryotic organism and showed 14-3-3 proteins as structural modulators and allosteric effectors of multi-domain binding partners.

Excipient selection for thermally stable enveloped and non-enveloped viral vaccine platforms in dry powders

Two enveloped viral vectors, vesicular stomatitis virus and influenza virus, and a non-enveloped viral vector, human adenovirus type 5, were encapsulated by spray drying to enhance thermal stability.Results with these candidates led to the hypothesis that stability performance of chosen excipients may be less virus-specific, as previously postulated in the literature, and more differentiated based on whether the virus has a lipid envelope. Spray dried samples were characterized for their thermal properties, RNA viability and in vitro viral activity after storage at 37 °C for up to 30 days or at 45 °C for up to 3 days. The enveloped viral vectors, as a group, were more thermally stable in trehalose while the non-enveloped viral vector showed higher activity with mannitol as the primary excipient in blends. Trehalose shows strong hydrogen bonds with the envelope's lipid membrane than the other carbohydrates, more effectively replacing water molecules while maintaining the fluidity of the membrane. Conversely, the small size of mannitol molecules was attributed to the more effective hydrogen bonding between water and the protein capsid of non-enveloped viral vectors. In all cases, a matrix with high glass transition temperature contributed to thermal stabilization through vitrification. This work suggests that carbohydrate stabilizer selection may be more dependent on the envelope rather than the specific viral vector, which, if universally true, will provide a guideline for future formulation development.