Trehalose Levels Research Articles

Assessing the Effects of Palm Oil Consumption on Life Expectancy, Metabolic Markers, and Oxidative Stress in Drosophila melanogaster.

Palm oil is the world's second most consumed vegetable oil, sourced from the tropical palm tree Elaeis guineensis. Its consumption has been associated with a higher incidence of cardiovascular disease, largely due to its elevated palmitic acid content, however those studies are contradictory and inconclusive. Wishing to contribute to this issue, the present study aims to investigate the molecular and toxicological effects of this oil and the involvement of oxidative stress, given its role in metabolic dysfunctions using Drosophila melanogaster. This study examines survival rates, and locomotor performance, oxidative status by analysis of lipid peroxidation, ROS formation, thiol levels and antioxidant enzyme activity, and metabolic parameters such as cholesterol and triglycerides, glucose, trehalose and glycogen levels. Exposure to palm oil concentrations of 10% and 30% resulted in a shortened lifespan, reduced locomotor performance, and increased lipid peroxidation, with lower thiol levels and antioxidant enzyme modulation. Cholesterol levels was increased whereas energetic fuels as glucose and glycogen and trehalose were decreased mainly after 10 days of exposure. These findings underscore the detrimental effects of high-fat diets containing palm oil on lifespan, antioxidant defenses, and metabolism in Drosophila melanogaster. This data highlights the potential risk associated with the habitual consumption of palm oil in the daily diet by population, particularly concerning cardiovascular health and metabolic function.

Shared genetic architecture links energy metabolism, behavior and starvation resistance along a power-endurance axis

Abstract Shared developmental, physiological, and molecular mechanisms can generate strong genetic covariances across suites of traits, constraining genetic variability, and evolvability to certain axes in multivariate trait space (“variational modules” or “syndromes”). Such trait suites will not only respond jointly to selection; they will also covary across populations that diverged from one another by genetic drift. We report evidence for such a genetically correlated trait suite that links traits related to energy metabolism along a “power-endurance” axis in Drosophila melanogaster. The “power” pole of the axis is characterized by high potential for energy generation and expenditure—high expression of glycolysis and TCA cycle genes, high abundance of mitochondria, and high spontaneous locomotor activity. The opposite “endurance” pole is characterized by high triglyceride (fat) reserves, locomotor endurance, and starvation resistance (and low values of traits associated with the “power” pole). This trait suite also aligns with the first principal component of metabolome; the “power” direction is characterized by low levels of trehalose (blood sugar) and high levels of some amino acids and their derivatives, including creatine, a compound known to facilitate energy production in muscles. Our evidence comes from six replicate “Selected” populations adapted to a nutrient-poor larval diet regime during 250 generations of experimental evolution and six “Control” populations evolved in parallel on a standard diet regime. We found that, within each of these experimental evolutionary regimes, the above traits strongly covaried along this “power-endurance” axis across replicate populations which diversified by drift, indicating a shared genetic architecture. The two evolutionary regimes also drove divergence along this axis, with Selected populations on average displaced towards the “power” direction compared to Controls. Aspects of this “power-endurance” axis resemble the “pace of life” syndrome and the “thrifty phenotype”; it may have evolved as part of a coordinated organismal response to nutritional conditions.

LdAMPKα2 knockdown accelerated the growth but depressed the chitin biosynthesis in Lymantria dispar larvae

AMPK (AMP-activated protein kinase) is a crucial cellular energy sensor across all eukaryotic species. Its multiple roles in maintaining energy homeostasis, regulating cellular metabolic processes have been widely investigated in mammals. In contrast, the function of AMPK in insects has been less reported. Here, we successfully identified three AMPK subunits from Lymantria dispar (L. dispar), a Lepidoptera pest in forestry. Based on that, in particular, the role of AMPK signaling in regulating larval development, as well as chitin biosynthesis was investigated by the application of RNAi-mediated LdAMPKα2 knockdown. The results indicated that knockdown of LdAMPKα2 significantly increased the body weight of L. dispar larvae, and dramatically upregulated the expression of LdmTOR, LdS6K and LdSREBP1, the key genes in mTOR (mammalian target of rapamycin) signaling pathway. While, it significantly reduced the expression of Ld4EBP, a critical repressor of mTOR pathway. Besides, the glucose level was increased and trehalose level was decreased in L. dispar after LdAMPKα2 silencing. Furthermore, we found that the chitin content in the epidermis, as well as the expressions of four key genes in the chitin biosynthesis pathway, LdGFAT, LdPAGM, LdUAP and LdCHSA, were significantly decreased after LdAMPKα2 knockdown. Taken together, these results revealed that AMPK signaling played a pivotal role in regulating the growth and development, as well as carbohydrate metabolism and chitin biosynthesis in L. dispar larvae. The findings expand our understanding of the comprehensive regulatory role of AMPK signaling in insects.

Integrated transcriptional and biochemical profiling suggests mechanisms associated with rapid cold hardening in adult Liriomyza trifolii (Burgess)

The leafminer Liriomyza trifolii causes severe economic damage on ornamental and horticultural crops in China. Rapid cold hardening (RCH) is a phenomenon where cold tolerance in insects can be significantly enhanced after a short-term acclimation to low temperatures. In this study, the regulation of transcription in response to cold hardening was investigated in L. trifolii adults, and fatty acids and cryoprotectant levels were measured. The composition of fatty acids changed after RCH treatment, and glucose and trehalose levels showed significant accumulation after acclimation, thus indicating that changes in fatty acids and cryoprotectants contribute to RCH in L. trifolii. RNA-seq was used to analyze transcriptional regulation after a 4 h hardening period and showed that differentially expressed genes clustered in multiple metabolic pathways, which indicates the importance of transcriptional regulation in RCH. This study expands our knowledge of biochemical and transcriptional changes in L. trifolii during cold hardening and provides a basis for further investigations aimed at understanding thermal adaptation in insects.

Bifenthrin at Sublethal Concentrations Suppresses Mating and Laying of Female Conogethes punctiferalis by Regulating Sex Pheromone Biosynthesis and JH Signals.

Conogethes punctiferalis, a polyphagous pest in Asia, infests various crops, causing severe economic losses. Its larvae feed inside plants, making management challenging, with conventional insecticides. This study examines sublethal bifenthrin effects on the reproductive capabilities of adult females. Findings show sublethal bifenthrin concentrations (LC1, LC10, LC20, and LC30) significantly reduce sex pheromone production and mating success in a dose-dependent manner. Furthermore, these sublethal exposures influence the expression of pheromone biosynthesis activating neuropeptide and key juvenile hormone signaling genes, including methoprene-tolerant and Krüppel-homologue 1. Enzyme activity assays and metabolite measurements indicated that sublethal bifenthrin exposure decreases trehalose and pyruvic acid levels, suppressing the enzyme activities required for sex pheromone biosynthesis. Additionally, bifenthrin exposure delays ovarian development, reduces ovary size, and decreases egg production and hatchability. These results suggest bifenthrin's potential in attract-and-kill strategies by disrupting essential pathways for pest control, offering insights for improved insecticide use and innovative pest management for C. punctiferalis.

Postnatal Wing Morph of Pea Aphids Regulates Hemolymph Trehalose Levels.

Trehalose, a nonreducing disaccharide composed of two glucose molecules, functions as a critical energy source in various insect tissues and organs and is the predominant sugar component of the hemolymph. The pea aphid, Acyrthosiphon pisum, exhibits higher hemolymph trehalose levels than other insects. However, the dynamics of hemolymph trehalose levels throughout its life stages remain unclear owing to the challenges associated with obtaining hemolymph from these small insects. Therefore, this study was conducted to quantify hemolymph trehalose levels in A. pisum using a fluorescent trehalose sensor (Tre-C04), which enhances green fluorescent protein fluorescence through the binding of trehalose to a ligand-binding protein fused to the fluorophore. Trehalose levels were successfully quantified in minimal hemolymph samples from individual aphids, with measurements spanning from the first nymphal stage to the adult stage in both the winged and wingless forms of A. pisum. Hemolymph trehalose levels remained relatively stable throughout the life cycle but exhibited a gradual increase with each developmental stage. Notably, adult winged aphids exhibited significantly higher hemolymph trehalose levels than wingless aphids. Given that wing morph determination occurs early in the nymphal stage, these findings suggest that hemolymph trehalose levels are regulated post-wing morph development. Further investigation of the expression of genes associated with trehalose metabolism revealed that trehalose phosphate synthase 2 levels were downregulated in early-stage wingless adults, whereas insulin-related peptide 5 levels were upregulated in wingless aphids. These findings indicate that A. pisum synthesizes trehalose during the winged adult stage to serve as an energy source for flight.

High sugar diet promotes tumor progression paradoxically through aberrant upregulation of pepck1

High dietary sugar (HDS), a contemporary dietary concern due to excessive intake of added sugars and carbohydrates, escalates the risk of metabolic disorders and concomitant cancers. However, the molecular mechanisms underlying HDS-induced cancer progression are not completely understood. We found that phosphoenolpyruvate carboxykinase 1 (PEPCK1), a pivotal enzyme in gluconeogenesis, is paradoxically upregulated in tumors by HDS, but not by normal dietary sugar (NDS), during tumor progression. Targeted knockdown of pepck1, but not pepck2, specifically in tumor tissue in Drosophila in vivo, not only attenuates HDS-induced tumor growth but also significantly improves the survival of Ras/Src tumor-bearing animals fed HDS. Interestingly, HP1a-mediated heterochromatin interacts directly with the pepck1 gene and downregulates pepck1 gene expression in wild-type Drosophila. Mechanistically, we demonstrated that, under HDS conditions, pepck1 knockdown reduces both wingless and TOR signaling, decreases evasion of apoptosis, reduces genome instability, and suppresses glucose uptake and trehalose levels in tumor cells in vivo. Moreover, rational pharmacological inhibition of PEPCK1, using hydrazinium sulfate, greatly improves the survival of tumor-bearing animals with pepck1 knockdown under HDS. This study is the first to show that elevated levels of dietary sugar induce aberrant upregulation of PEPCK1, which promotes tumor progression through altered cell signaling, evasion of apoptosis, genome instability, and reprogramming of carbohydrate metabolism. These findings contribute to our understanding of the complex relationship between diet and cancer at the molecular, cellular, and organismal levels and reveal PEPCK1 as a potential target for the prevention and treatment of cancers associated with metabolic disorders.

Paternal zinc deficiency alters offspring metabolic status in Drosophila melanogaster

BackgroundThis study delves into the understudied yet potentially crucial role of paternal zinc deficiency in programming offspring metabolic outcomes. By examining paternal zinc deficiency, we aim to shed light on a previously unexplored avenue with the potential to significantly impact future generations. We investigated the intergenerational effects of paternal zinc deficiency on metabolic parameters in Drosophila melanogaster. MethodsDietary zinc deficiency was induced by supplementing the diet of Drosophila F0 male flies with TPEN (N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine) from egg stage. The F0 male flies after eclosion were mated with age-matched virgin female flies from the control group, resulting in the F1 offspring generation. The F1 generation were then cultured on a standard diet for subsequent metabolic analyses, including assessments of body weight, locomotion, and levels of glucose, trehalose, glycogen, and triglycerides as well as the expression of related genes. ResultsWe observed an increase (p<0.05) in body weight in male parent flies and female offspring. Negative geotaxis performance was also impaired in the female offspring. Paternal zinc deficiency exerted distinct effects on carbohydrate and lipid metabolism, as evidenced by a significant (p<0.05) increase in trehalose and triglyceride levels in both parent and offspring. Additionally, zinc deficiency led to alterations in the expression of key metabolic genes, including significant (p<0.05) increase in DILP2 mRNA levels, highlighting potential links to insulin signaling. Also, there were reduced mRNA levels of SOD1 and CAT in both parental and offspring generations. Parental zinc deficiency also increased the expression of Eiger and UPD2 mRNA in the offspring, suggesting potential perturbations in the immune response system. ConclusionThese findings underscore the link between zinc status and various physiological and molecular processes, revealing both immediate and intergenerational impacts on metabolic, antioxidant, and inflammatory pathways and providing valuable insights on the implications of paternal zinc deficiency in Drosophila melanogaster.

Evaluating cellular roles and phenotypes associated with trehalose degradation genes in Saccharomyces cerevisiae.

In the yeast Saccharomyces cerevisiae, 2 types of trehalase activities have been described. Neutral trehalases (Nth1 and Nth2) are considered to be the main proteins that catalyze intracellular trehalose mobilization. In addition to Nth1 and Nth2, studies have shown that acid trehalase Ath1 is required for extracellular trehalose degradation. Although both neutral and acid-type trehalases have been predominantly investigated in laboratory strains of S. cerevisiae, we sought to examine the phenotypic consequences of disrupting these genes in wild strains. In this study, we constructed mutants of the trehalose degradation pathway (NTH1, NTH2, and ATH1) in 5 diverse S. cerevisiae strains to examine whether published lab strain phenotypes are also exhibited by wild strains. For each mutant, we assessed a number of phenotypes for comparison to trehalose biosynthesis mutants, including trehalose production, glycogen production, cell size, acute thermotolerance, high-temperature growth, sporulation efficiency, and growth on a variety of carbon sources in rich and minimal medium. We found that all trehalase mutants including single deletion nth1Δ, nth2Δ, and ath1Δ, as well as double deletion nth1nth2Δ, accumulated higher intracellular trehalose levels compared to their isogenic wild-type cells. Also, nth1Δ and nth1Δnth2Δ mutants exhibited mild thermal sensitivity, suggesting a potential minor role for trehalose mobilization when cells recover from stress. In addition, we evaluated phenotypes more directly relevant to trehalose degradation, including both extracellular and intracellular trehalose utilization. We discovered that intracellular trehalose hydrolysis is critical for typical spore germination progression, highlighting a role for trehalose in cell cycle regulation, likely as a storage carbohydrate providing glycolytic fuel. Additionally, our work provides further evidence suggesting Ath1 is indispensable for extracellular trehalose utilization as a carbon source, even in the presence of AGT1.

Enhancing olive tree (Olea europaea) rhizosphere dynamics: Co-inoculation effects of arbuscular mycorrhizal fungi and plant growth- promoting rhizobacteria in field experiments

We investigated the outcome of the interaction between the arbuscular mycorrhizal fungus (AMF) Rhizophagus (R) irregularis DAOM 197198 and the Plant-Growth-Promoting Rhizobacteria (PGPR) (mix of Bacillus megaterium, Burkholdria cedrus and Streptomyces beta-vulgaris) by conducting an olive field experiment. Our data provide evidence that the co-inoculation of R. irregularis and PGPR has important effects on the rhizosphere microbial community. The largest proportional increase was found for the PLFA biomarkers indicative of Gram-negative bacteria (16:1ω9, 18:1ω7 and 18:1ω9), fungi (18:2ω6) and actinobacteria (10Me16:0 and 10Me18:0). Microbial inoculants application of all tested treatments caused a significant decrease in the level of trehalose in the olive rhizosphere. The most pronounced decrease was observed in the plant inoculated with R. intraradices only, suggesting that the presence of AMF may have relaxed the bacterial stress. Co-inoculation of PGPR and AMF significantly improved the nutritional status of olive roots. Specifically, the interaction of PGPR and R. intraradices led to an increase in N (26 %), P (60 %), Fe (25 %), Mn (18 %), Zn (26 %), B (22 %) and Cu (14 %) compared with the control. We also found that the co-inoculation of AMF with PGPR causes a shift in the accumulation of secondary metabolites in olive roots. In particular, the most important effect induced by AMF was an improvement of oleuropein concentration, while co-inoculation of R. irregularis and PGPR positively modulated verbascoside concentration. The novelty of the present work lies in the use of microbial inoculants in the field of olive trees. This approach provided direct information regarding the advantages of using AMF and PGPR inoculants, allowing the reduction of chemical inputs and positively influencing the olive tree performance.

20(S)-ginsenoside Rg3 protects against diabetic muscle atrophy by promoting myoblastic differentiation and protecting mitochondrial function

BackgroundHigh glucose levels are a primary cause of diabetes-associated cellular dysfunction and tissue damage. Muscles are the key insulin target organ and therefore, have a high level of sensitivity to hyperglycemia. Our previous study revealed that 20(S)-ginsenoside Rg3 (S-Rg3) is a monomer with a good myogenic differentiation effect in ginsenoside. Furthermore, it can alleviate dexamethasone-induced muscle atrophy by protecting mitochondrial function. However, whether S-Rg3 is effective for diabetic-induced muscle atrophy has not been reported. PurposeThis study aimed to investigate the protective effect of S-Rg3 on diabetic-induced muscle atrophy. MethodsC2C12 myoblasts, Drosophila, and mice were used as model systems, and the protective effect of S-Rg3 on diabetes was evaluated by assessing the levels of glucose and lipids. Furthermore, H&E, toluidine blue, Giemsa, and immunofluorescence staining were performed to detect the effects of S-Rg3 on muscle atrophy and myogenic differentiation. Moreover, the effects of S-Rg3 on mitochondrial morphology and function were also evaluated by electron microscopy, flow cytometry, and Seahorse. In addition, the underlying pathways of S-Rg3 effects were detected by Western blot. The related inhibitors and gene mutations in Drosophila were used for validation. ResultsThe analysis of diabetic mice model fed with a high-fat diet (HFD) and high glucose (HG) revealed that in the injured C2C12 myoblasts, S-Rg3 treatment significantly reduced the levels of triglycerides and glucose. Furthermore, it promoted the differentiation of myoblasts and inhibited mitochondrial dysfunction. In the Drosophila HG and HFD diabetic model, S-Rg3 reduced triglyceride and trehalose levels, increased climbing distance values, promoted myoblasts differentiation, preserved mitochondrial function, and inhibited muscle atrophy. Mechanistically, the beneficial effects of S-Rg3 were at least partially associated with the phosphorylation of AMPK and FoxO3 together with the inhibition of Smad3 phosphorylation, this pathway was validated by the UAS-AMPKα-RNAi Drosophila model. ConclusionIn summary, this study revealed mechanistic insights into how S-Rg3 protects against diabetes-associated muscle atrophy in cells, Drosophila, and mice.

Exendin-4 Caused Growth Arrest by Regulating Sugar Metabolism in Hyphantria cunea (Lepidoptera: Erebidae) Larvae.

Insects' growth and development are highly dependent on energy supply, with sugar metabolism playing a pivotal role in maintaining homeostasis and regulating physiological processes. The present study investigated the effects of exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, on the growth, development, glycolysis, and energy metabolism of fourth-instar larvae of the fall webworm, Hyphantria cunea. We determined the impact of exendin-4 on larval growth and nutritional indices, analyzed the responses of glycolytic and metabolic pathways, and revealed the underlying regulatory mechanisms. Exendin-4 treatment significantly decreased growth and nutritional indices, influenced the activity of digestive enzymes, and induced changes in metabolite profiles, particularly affecting energy substance metabolism. We observed an increase in the glycogen content and a decrease in glucose and trehalose levels in the hemolymph, suggesting a regulatory effect on blood sugar homeostasis. Furthermore, exendin-4 promoted glycolysis by enhancing the activities and expressions of key glycolytic enzymes, leading to an increase in pyruvate production. This was accompanied by a reduction in ATP levels and the activation of AMP-activated protein kinase (AMPK), which may underlie the growth arrest in larvae. Our findings provide novel insights into the effects of exendin-4 on insect responses from an energy metabolism perspective and may contribute to the development of GLP-1R agonists for pest management.

The osmoregulated metabolism of trehalose contributes to production of type 1 fimbriae and bladder colonization by extraintestinal Escherichia coli strain BEN2908.

In Escherichia coli, the disaccharide trehalose can be metabolized as a carbon source or be accumulated as an osmoprotectant under osmotic stress. In hypertonic environments, E. coli accumulates trehalose in the cell by synthesis from glucose mediated by the cytosolic enzymes OtsA and OtsB. Trehalose in the periplasm can be hydrolyzed into glucose by the periplasmic trehalase TreA. We have previously shown that a treA mutant of extraintestinal E. coli strain BEN2908 displayed increased resistance to osmotic stress by 0.6 M urea, and reduced production of type 1 fimbriae, reduced invasion of avian fibroblasts, and decreased bladder colonization in a murine model of urinary tract infection. Since loss of TreA likely results in higher periplasmic trehalose concentrations, we wondered if deletion of otsA and otsB genes, which would lead to decreased internal trehalose concentrations, would reduce resistance to stress by 0.6 M urea and promote type 1 fimbriae production. The BEN2908ΔotsBA mutant was sensitive to osmotic stress by urea, but displayed an even more pronounced reduction in production of type 1 fimbriae, with the consequent reduction in adhesion/invasion of avian fibroblasts and reduced bladder colonization in the murine urinary tract. The BEN2908ΔtreAotsBA mutant also showed a reduction in production of type 1 fimbriae, but in contrast to the ΔotsBA mutant, resisted better than the wild type in the presence of urea. We hypothesize that, in BEN2908, resistance to stress by urea would depend on the levels of periplasmic trehalose, but type 1 fimbriae production would be influenced by the levels of cytosolic trehalose.

Identification of sulfakinin receptor regulating feeding behavior and hemolymph trehalose homeostasis in the silkworm, Bombyx mori

Feeding behavior, the most fundamental physiological activity, is controlled by two opposing groups of factors, orexigenic and anorexigenic factors. The sulfakinin family, an insect analogue of the mammalian satiety factor cholecystokinin (CCK), has been shown to suppress food intake in various insects. Nevertheless, the mechanisms through which sulfakinin regulates feeding behavior remain a biological question. This study aimed to elucidate the signaling pathway mediated by the anorexigenic peptide sulfakinin in Bombyx mori. We identified the Bombyx mori neuropeptide G protein-coupled receptor A9 (BNGR-A9) as the receptor for sulfakinin through functional assays. Stimulation with sulfakinin triggered a swift increase in intracellular IP3, Ca2+, and a notable enhancement of ERK1/2 phosphorylation, in a manner sensitive to a Gαq-specific inhibitor. Treatment with synthetic sulfakinin resulted in decreased food consumption and average body weight. Additionally, administering synthetic sulfakinin to silkworms significantly elevated hemolymph trehalose levels, an effect markedly reduced by pre-treatment with BNGR-A9 dsRNA. Consequently, our findings establish the sulfakinin/BNGR-A9 signaling pathway as a critical regulator of feeding behavior and hemolymph trehalose homeostasis in Bombyx mori, highlighting its roles in the negative control of food intake and the positive regulation of energy balance.

The white lupin trehalase gene LaTRE1 regulates cluster root formation and function under phosphorus deficiency.

Under phosphorus (P) deficiency, white lupin (Lupinus albus L.) forms specialized root structure, called cluster root (CR), to improve soil exploration and nutrient acquisition. Sugar signaling is thought to play a vital role in the development of CR. Trehalose and its associated metabolites are the essential sugar signal molecules that link growth and development to carbon metabolism in plants, however, their roles in the control of CR are still unclear. Here, we investigated the function of the trehalose metabolism pathway by pharmacological and genetic manipulation of the activity of trehalase in white lupin, the only enzyme that degrades trehalose into glucose. Under P deficiency, validamycin A treatment, which inhibits trehalase, led to the accumulation of trehalose and promoted the formation of CR with enhanced organic acid production, whereas overexpression of the white lupin TREHALASE1 (LaTRE1) led to decreased trehalose levels, lateral rootlet density, and organic acid production. Transcriptomic and virus-induced gene silencing (VIGS) results revealed that LaTRE1 negatively regulates the formation of CRs, at least partially, by the suppression of LaLBD16, whose putative ortholog in Arabidopsis (Arabidopsis thaliana) acts downstream of ARF7- and ARF19-dependent auxin signaling in lateral root formation. Overall, our findings provide an association between the trehalose metabolism gene LaTRE1 and CR formation and function with respect to organic acid production in white lupin under P deficiency.

Production of heat-resistant blastospores by Cordyceps javanica IF-1106 through optimizing metal ions composition

Heat tolerance of fungi is critical for field stability and efficacy of fungal insecticides. Components of the medium, such as carbon source, nitrogen source and metal ions, contribute to the thermotolerance of fungi. In this study, several metal ions were detected to establish their effects on the sporulation and thermotolerance of the blastospores of Cordyceps javanica IF-1106 when cultured in liquid medium. The results showed that metal ions play different roles in sporulation and thermotolerance of the fungi. Mn2+ greatly increased the thermotolerance of the blastospores, and Fe2+ increased the thermotolerance slightly. However, both has no or negative effects on sporulation of the fungi. In the case of Cu2+ and Fe3+, sporulation yield and thermotolerance of the blastospores increased significantly. In addition, intracellular trehalose and mannitol involved in thermotolerance of fungi were extracted and then quantified by ion chromatography. We find that the trehalose and mannitol are higher in the presence of Mn2+, implying that Mn2+ could adjust the intracellular trehalose and mannitol level confers the blastospores with higher tolerance to thermal stress. Further, Response Surface Methodology (RSM) was applied to screen the optimal composition of metal ions. When the formula was MnSO4·H2O 8 mg/L, CuSO4·5H2O 5 mg/L, FeSO4·7H2O 11 mg/L, FeCl3·6H2O 8 mg/L, maximum sporulation yield and GT50 were obtained. Lastly, the virulence of the blastospores to Acyrthosiphon pisum was validated, a higher virulence is achieved with decreased LT50 (2 d) and LC50 (2.37 × 104 blastospores mL−1). In conclusion, thermotolerant blastospores of C. javanica IF-1106 and higher sporulation yield could be achieved by optimizing the metal ions composition, which helps to determine the formula for larger scale fermentation process.

Membrane Lipids and Osmolytes in the Response of the Acidophilic Basidiomycete Phlebiopsis gigantea to Heat, Cold, and Osmotic Shocks.

Previously, we found for the first time the participation of osmolytes in adaptation to acidic conditions in three acidophilic fungi. Because trehalose can protect membranes, we hypothesized a relationship between osmolyte and membrane systems in adaptation to stressors. In the mycelium of Phlebiopsis gigantea, the level of osmolytes reaches 8% of the dry mass, while trehalose and arabitol make up 60% and 33% of the sum, respectively. Cold shock does not change the composition of osmolytes, heat shock causes a twofold increase in the trehalose level, and osmotic shock leads to a marked increase in the amount of trehalose and arabitol. Predominance of phospholipids (89% of the sum) and low proportions of sterols and sphingolipids are characteristic features of the membrane lipids' composition. Phosphatidic acids, along with phosphatidylethanolamines and phosphatidylcholines, are the main membrane lipids. The composition of the membrane lipids remains constant under all shocks. The predominance of linoleic (75% of the sum) and palmitic (20%) acids in phospholipids results in a high degree of unsaturation (1.5). Minor fluctuations in the fatty acid composition are observed under all shocks. The results demonstrate that maintaining or increasing the trehalose level provides stability in the membrane lipid composition during adaptation.

AnWRKY29 and AnHSP90 synergistically modulate trehalose levels in a desert shrub leaves during osmotic stress.

Trehalose, a biological macromolecule with osmotic adjustment properties, plays a crucial role during osmotic stress. As a psammophyte, Ammopiptanthus nanus relies on the accumulation of organic solutes to respond to osmotic stress. We utilized virus-induced gene silencing technology for the first time in the desert shrub A. nanus to confirm the central regulatory role of AnWRKY29 in osmotic stress, as it controls the transcription of AnTPS11 (trehalose-6-phosphate synthase 11). Further investigation has shown that AnHSP90 may interact with AnWRKY29. The AnHSP90 gene is sensitive to osmotic stress, underscoring its pivotal role in orchestrating the response to such adverse conditions. By directly targeting the W-box element within the AnTPS11 promoter, AnWRKY29 effectively enhances the transcriptional activity of AnTPS11, which is facilitated by AnHSP90. This discovery highlights the critical role of AnWRKY29 and AnHSP90 in enabling organisms to adapt to and cope effectively with osmotic stress, which can be a crucial factor in A. nanus survival and overall ecological resilience. Collectively, uncovering the molecular mechanisms underlying the osmotic responses of A. nanus is paramount for comprehending and augmenting the osmotic tolerance mechanisms of psammophyte shrub plants.

Regulation of forager honey bee appetite independent of the glucose-insulin signaling pathway.

To maintain energetic homeostasis the energetic state of the individual needs to communicate with appetite regulatory mechanisms on a regular basis. Although hunger levels indicated by the energetic state and appetite levels, the desire for food intake, tend to be correlated, and on their own are well studied, how the two cross-talk and regulate one another is less known. Insects, in contrast to vertebrates, tend to have trehalose as the primary sugar found in the hemolymph, which could possibly serve as an alternative monitor of the energetic state in comparison to the glucose-insulin signaling pathway, found in vertebrates. We investigate how manipulating hemolymph sugar levels alter the biogenic amines in the honey bee brain, appetite levels, and insulin like peptide gene expression, across three age classes, to determine how the energetic state of the honey bee might be connected to appetite regulation. We found that only in the forager bees, with a lowering of hemolymph trehalose levels, there was an increase in octopamine and a decrease in tyramine levels in the honey bee brain that corresponded with increased appetite levels, while there was no significant changes in Insulin Like Peptide-1 or 2 gene expression. Our findings suggest that hemolymph trehalose levels aid in regulating appetite levels, in forager bees, via octopamine and tyramine, and this regulation appears to be functioning independent of the glucose insulin signaling pathway. Whether this potentially more direct and rapid appetite regulatory pathway can be generalized to other insects, which also undergo energy demanding activities, remains to be investigated.

Trehalose 6-phosphate synthase gene rdtps1 contributes to thermal acclimation in Rhyzopertha dominica

BackgroundThe lesser grain borer (Rhyzopertha dominica), a worldwide primary pest of stored grain, causes serious economic losses and threatens stored food safety. R. dominica can respond to changes in temperature, especially the adaptability to heat. In this study, transcriptome analysis of R. dominica exposed to different temperatures was performed to elucidate differences in gene expression and the underling molecular mechanism.ResultsIsoform-sequencing generated 17,721,200 raw reads and yielded 20,416 full-length transcripts. A total of 18,880 (92.48%) transcripts were annotated. We extracted RNA from R. dominica reared at 5 °C (cold stress), 15 °C (cold stress), 27 °C (ambient temperature) and 40 °C (heat stress) for RNA-seq. Compared to those of control insects reared at 27 °C, 119, 342, and 875 differentially expressed genes (DEGs) were identified at 5 °C, 15 °C, and 40 °C, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that pathways associated with “fatty acid metabolism”, “fatty acid biosynthesis”, “AMPK signaling pathway”, “neuroactive ligand receptor interaction”, and “longevity regulating pathway-multiple species” were significantly enriched. The functional annotation revealed that the genes encoding heat shock proteins (HSPs), fatty acid synthase (FAS), phospholipases (PLA), trehalose transporter (TPST), trehalose 6-phosphate synthase (TPS), and vitellogenin (Vg) were most likely involved in temperature regulation, which was also validated by RT-qPCR. Seven candidate genes (rdhsp1, rdfas1, rdpla1, rdtpst1, rdtps1, rdvg1, and rdP450) were silenced in the RNA interference (RNAi) assay. RNAi of each candidate gene suggested that inhibiting rdtps1 expression significantly decreased the trehalose level and survival rate of R. dominica at 40 °C.ConclusionsThese results indicated that trehalose contributes to the high temperature resistance of R. dominica. Our study elucidates the molecular mechanisms underlying heat tolerance and provides a potential target for the pest management in R. dominica.