Hemolymph Sugar Research Articles

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.

Behavioral state-dependent modulation of insulin-producing cells in Drosophila

Insulin signaling plays a pivotal role in metabolic control and aging, and insulin accordingly is a key factor in several human diseases. Despite this importance, the invivo activity dynamics of insulin-producing cells (IPCs) are poorly understood. Here, we characterized the effects of locomotion on the activity of IPCs in Drosophila. Using invivo electrophysiology and calcium imaging, we found that IPCs were strongly inhibited during walking and flight and that their activity rebounded and overshot after cessation of locomotion. Moreover, IPC activity changed rapidly during behavioral transitions, revealing that IPCs are modulated on fast timescales in behaving animals. Optogenetic activation of locomotor networks exvivo, in the absence of actual locomotion or changes in hemolymph sugar levels, was sufficient to inhibit IPCs. This demonstrates that the behavioral state-dependent inhibition of IPCs is actively controlled by neuronal pathways and is independent of changes in glucose concentration. By contrast, the overshoot in IPC activity after locomotion was absent exvivo and after starvation, indicating that it was not purely driven by feedforward signals but additionally required feedback derived from changes in hemolymph sugar concentration. We hypothesize that IPC inhibition during locomotion supports mobilization of fuel stores during metabolically demanding behaviors, while the rebound in IPC activity after locomotion contributes to replenishing muscle glycogen stores. In addition, the rapid dynamics of IPC modulation support a potential role of insulin in the state-dependent modulation of sensorimotor processing.

Effects of Varroa destructor on Hemolymph Sugars and Secondary Infections in Honeybees (Apis mellifera)

The European honeybee contributes to the agriculture by its pollination; however, the overwintering loss rate over the last decades is worrisome. Varroa destructor is considered one of the most important causes of bee colony declines. This project aims to correlate the infestation by varroa to the hemolymph sugar concentrations and bacterial and viral coinfections. Six highly infested and six control hives were compared over time. Pooled hemolymph samples from honeybees were collected for sugar concentration measurements using a previously validated portable glucometer. The hemolymph samples were submitted for bacteriology. Multiplex RT-PCR analysis was performed on honeybees for six viruses: DWV-A, DWV-B, BQCV, ABPV, KBV, and IAPV. There was also no predominance of pathogenic bacteria. In September, sugar concentrations in hemolymph were significantly lower in highly infested hives than in control hives. Infested hives showed markedly higher viral loads except for ABPV. DWV-A and BQCV viral loads from highly infested hives were significantly higher in September compared to July. A continued and severe exposure to varroa leads to increased viral charges and decreased sugar concentrations, suggesting alterations in immunity, metabolism, and reserve mobilization. These parameters contribute to the weakening and mortality of the colonies.

Respiratory Response and Hemolymph Sugar Level of The Crab Barytelphusa gureini Exposed To Heavy Metals

To explore the respiratory and metabolic responses, the fresh water crabs Barytelphusa gureini, were exposed to sublethal concentrations (2.0 & 2.25 µg/L) of cadmium chloride and copper sulphate respectively. Oxygen consumption and hemolymph sugar level of the animals were estimated to study the stress caused by these heavy metal toxicants. These animals after acclimatization to the laboratory conditions exposed for 0, 24, 48, 72 and 96 hrs to the toxicants. Total oxygen consumption was studied by Winkler’s method and the hemolymph sugar level was estimated by Anthrone method. In the present study, total oxygen consumption showed a gradual decline trend from 0 to 96 hrs in the experimental animals exposed to cadmium chloride, while the hemolymph sugar level recorded an elevation, with maximum increase at 96 hrs. These results showed that cadmium was found to be more toxic than copper metal.

Proton gradient mediates hemolymph trehalose influx into aphid bacteriocytes.

Aphids harbor proteobacterial endosymbionts such as Buchnera aphidicola housed in specialized bacteriocytes derived from host cells. The endosymbiont Buchnera supplies essential amino acids such as arginine to the host cells and, in turn, obtains sugars needed for its survival from the hemolymph. The mechanism of sugar supply in aphid bacteriocytes has been rarely studied. It also remains unclear how Buchnera acquires its carbon source. The hemolymph sugars in Acyrthosiphon pisum are composed of the disaccharide trehalose containing two glucose molecules. Here, we report for the first time that trehalose is transported and used as a potential carbon source by Buchnera across the bacteriocyte plasma membrane via trehalose transporters. The current study characterized the bacteriocyte trehalose transporter Ap_ST11 (LOC100159441) using the Xenopus oocyte expression system. The Ap_ST11 transporter was found to be proton-dependent with a Km value ≥700 mM. We re-examined the hemolymph trehalose at 217.8 mM using a fluorescent trehalose sensor. The bacteriocytes did not obtain trehalose by facilitated diffusion along the gradient across cellular membranes. These findings suggest that trehalose influx into the bacteriocytes depends on the extracellular proton-driven secondary electrochemical transporter.

The Role of Insulin-like Peptide in Maintaining Hemolymph Glucose Homeostasis in the Pacific White Shrimp Litopenaeus vannamei.

Insulin-like peptide (ILP) has been identified in various crustaceans, but whether it has a similar function in regulating hemolymph glucose as vertebrate insulin is unclear. We analyzed the components of hemolymph sugar in the Pacific white shrimp, Litopenaeus vannamei, and investigated the changes of hemolymph glucose concentration and the expressions of ILP and glucose metabolism genes under different treatments. We found glucose was a major component of hemolymph sugar in shrimp. Starvation caused hemolymph glucose to rise first and then decline, and the raised hemolymph glucose after exogenous glucose injection returned to basal levels within a short time, indicating that shrimp have a regulatory mechanism to maintain hemolymph glucose homeostasis. In addition, injections of bovine insulin and recombinant LvILP protein both resulted in a fast decline in hemolymph glucose. Notably, RNA interference of LvILP did not significantly affect hemolymph glucose levels, but it inhibited exogenous glucose clearance. Based on the detection of glucose metabolism genes, we found LvILP might maintain hemolymph glucose stability by regulating the expression of these genes. These results suggest that ILP has a conserved function in shrimp similar to insulin in vertebrates and plays an important role in maintaining hemolymph glucose homeostasis.

Sima, a Drosophila homolog of HIF-1α, in fat body tissue inhibits larval body growth by inducing Tribbles gene expression.

Limited oxygen availability impairs normal body growth, although the underlying mechanisms are not fully understood. In Drosophila, hypoxic responses in the larval fat body (FB) disturb the secretion of insulin-like peptides from the brain, inhibiting body growth. However, the cell-autonomous effects of hypoxia on the insulin-signaling pathway in larval FB have been underexplored. In this study, we aimed to examine the effects of overexpression of Sima, a Drosophila hypoxia-inducible factor-1 (HIF-1) α homolog and a key component of HIF-1 transcription factor essential for hypoxic adaptation, on the insulin-signaling pathway in larval FB. Forced expression of Sima in FB reduced the larval body growth with reduced Akt phosphorylation levels in FB cells and increased hemolymph sugar levels. Sima-mediated growth inhibition was reversed by overexpression of TOR or suppression of FOXO. After Sima overexpression, larvae showed higher expression levels of Tribbles, a negative regulator of Akt activity, and a simultaneous knockdown of Tribbles completely abolished the effects of Sima on larval body growth. Furthermore, a reporter analysis revealed Tribbles as a direct target gene of Sima. These results suggest that Sima in FB evokes Tribbles-mediated insulin resistance and consequently protects against aberrant insulin-dependent larval body growth under hypoxia.

Physiological Alterations in Deletion Mutants of Two Insulin-Like Peptides Encoded in Maruca vitrata Using CRISPR/Cas9.

Most insect species encode multiple insulin-like peptides (ILPs) that exhibit functional overlaps in mediating physiological processes such as development and reproduction. Why do they need multiple ILPs? To address this question, we tested a hypothesis of the requirement of multiple ILPs by generating mutants lacking individual ILP genes using the CRISPR/Cas9 technology. Two ILPs (ILP1 and ILP2) in the legume pod borer, Maruca vitrata, mediate similar physiological processes such as hemolymph sugar level, larval development, and adult reproduction. Individual knock-out mutants (ΔILP1 and ΔILP2) were generated. They showed successful development from larvae to adults. However, they suffered from high hemolymph sugar levels by enhancing trehalose titers in the hemolymph. The hyperglycemic effect was more evident in ΔILP2 mutants than in ΔILP1 mutants. Both mutants showed increased expression of trehalose-6-phosphate synthase but suppressed expression of trehalase. These mutants also showed altered expression patterns of insulin signaling components. Expression levels of insulin receptor and Akt genes were upregulated, while those of FOXO and Target of rapamycin genes were downregulated in these mutants. These alterations of signal components resulted in significant retardation of immature development and reduced body sizes. ΔILP1 or ΔILP2 females exhibited poor oocyte development. Bromo-uridine incorporation was much reduced at the germarium of ovarioles of these mutants compared with wild females. Expression of the vitellogenin gene was also reduced in these mutants. Furthermore, males of these deletion mutants showed impaired reproductive activities when they mated with wild-type females. These results suggest that both ILPs are required for mediating larval development and adult reproduction in M. vitrata.

Trehalose metabolism in the Chinese mitten crab Eriocheir sinensis: Molecular cloning of trehalase and its expression during temperature stress

Trehalose, a nonreducing disaccharide, serves as the principal hemolymph sugar involved in energy metabolism and protection against stress in crustaceans. While there have been recent advances in understanding of trehalose biosynthesis in crustaceans, the catabolism of trehalose remains poorly understood. Trehalase catalyzes the hydrolysis of trehalose into glucose and plays a crucial physiological role in most organisms. In this study, we isolated and characterized a trehalase gene, EsTreh, in the Chinese mitten crab Eriocheir sinensis. The full-length EsTreh cDNA sequence was 2488 bp with an open reading frame (ORF) of 1914 bp encoding a protein of 638 amino acids with a deduced molecular weight of 73.53 kDa and a pI of 6.10. The Es-Treh protein contains signature motifs 1 and 2. The transcript levels of EsTreh were significantly inhibited after 24 h of heat and cold stress in E. sinensis. The trehalose content was maintained during 12 h of cold and heat stress, but increased significantly after 24 h of stress. The glucose and lactic acid contents showed a trend of initial rapid increase followed by an extended decline. The glycogen content significantly decreased with the extension of thermal stress. Our study provided the first description of trehalase in crustaceans and demonstrated that trehalase contributes to the accumulation of trehalose during thermal stress. Our findings suggest that the glycogenolysis and gluconeogenesis pathways might be involved in the transformation of glycogen and lactic acid to trehalose.

Glucose-mediated proliferation of a gut commensal bacterium promotes Plasmodium infection by increasing mosquito midgut pH.

SUMMARYPlant-nectar-derived sugar is the major energy source for mosquitoes, but its influence on vector competence for malaria parasites remains unclear. Here, we show that Plasmodium berghei infection of Anopheles stephensi results in global metabolome changes, with the most significant impact on glucose metabolism. Feeding on glucose or trehalose (the main hemolymph sugars) renders the mosquito more susceptible to Plasmodium infection by alkalizing the mosquito midgut. The glucose/trehalose diets promote proliferation of a commensal bacterium, Asaia bogorensis, that remodels glucose metabolism in a way that increases midgut pH, thereby promoting Plasmodium gametogenesis. We also demonstrate that the sugar composition from different natural plant nectars influences A. bogorensis growth, resulting in a greater permissiveness to Plasmodium. Altogether, our results demonstrate that dietary glucose is an important determinant of mosquito vector competency for Plasmodium, further highlighting a key role for mosquito-microbiota interactions in regulating the development of the malaria parasite.

Gas chromatography – Mass spectrometry as a preferred method for quantification of insect hemolymph sugars

Insects, due to their small size, have limited energy storage space, but they also have high metabolic rate, so their hemolymph sugars are incredibly dynamic and play a number of important physiological functional roles in maintaining energetic homeostasis. In contrast to vertebrates, trehalose is generally the primary sugar found in insect hemolymph, which is followed by glucose and fructose. Many analytical chemistry methods exist to measure sugars, yet a direct comparison of methods that can measure all three simultaneously, and trehalose in particular, from low sample volumes, are sparse. Using the honey bee as a model, we directly compare the leading current methods of using High Performance Liquid Chromatography (HPLC) with an evaporative light-scattering detector and Gas Chromatography coupled with Mass Spectrometry (GC–MS) to determine which method would be better for measuring trehalose, glucose, and fructose in terms of reproducibility, accuracy, and sensitivity. Furthermore, we injected the enzyme inhibitors trehalozin (a trehalase inhibitor) and sorbose (a trehalase p-synthase inhibitor) to manipulate the trehalose levels in honey bee foragers as a proof of concept that this sugar can be altered independently of hemolymph glucose and fructose levels. Overall the HPLC method was less reproducible for measuring fructose and glucose, and it also had lower sensitivity for measuring trehalose. Consequently, significant differences in trehalose levels within the forager class were only detected with the GC–MS and not the HPLC method. Lastly, using the GC–MS method in the follow up study we found that trehalozin and sorbose causes a significant increase and decrease of trehalose levels respectively, in forager honey bees, independent of the glucose and fructose levels, ten minutes after injection. Taken together, these methods will provide useful tools for future studies exploring the many different physiological functional roles that trehalose can play in maintaining insect energetic homeostasis.

Insulin signaling mediates previtellogenic development and enhances juvenile hormone-mediated vitellogenesis in a lepidopteran insect, Maruca vitrata

BackgroundInsulin/insulin-like growth peptide signaling (IIS) down-regulates hemolymph sugar level and facilitates larval growth in the soybean pod borer, Maruca vitrata. The objective of this study is to determine whether IIS of M. vitrata can mediate ovarian development of adult females.ResultsA pair of ovaries consists of 8 ovarioles, each of which is separated into distal germarium and proximal vitellarium in M. vitrata. In the germarium, oocyte development occurred with active mitotic activity which was visible by incorporating bromodeoxyribose uridine. Previtellogenic development and subsequent vitellogenesis began soon after adult emergence. They continued with increase of female age. Oocyte development was facilitated by up-regulation of vitellogenin (Vg) and Vg receptor (VgR) gene expression. Larval diets significantly influenced on ovarian development of M. vitrata because oocyte development varied with pupal size derived from larvae treated with different nutritional diets. Its ovarian development was dependent on endocrine signal(s) from the head because decapitation soon after adult emergence prevented oogenesis and subsequent vitellogenesis along with marked reduction of Vg and VgR expression. Topical application of juvenile hormone (JH) significantly recovered its ovarian development whereas farnesoic acid (a precursor of JH biosynthesis) or 20-hydroxyecdysone treatment did not. JH stimulated vitellogenesis and choriogenesis, but not previtellogenic development. In contrast, insulin injection to decapitated females stimulated oocyte differentiation and vitellogenesis along with increase of Vg and VgR expression. To further analyze the effect of insulin on ovarian development, expression of four IIS components (InR, FOXO, Akt, and TOR) genes was manipulated by RNA interference. Hemocoelic injection of gene-specific double stranded RNAs significantly reduced their target gene mRNA levels and interfered with ovarian development. An addition of insulin to JH treatment against decapitated females enhanced the gonadotropic effect of JH by stimulating oogenesis.ConclusionsIIS plays crucial role in mediating previtellogenic development of M. vitrata in response to nutrient signal. It also enhances the gonadotropic effect of JH II on vitellogenesis.

Appetite is correlated with octopamine and hemolymph sugar levels in forager honeybees.

Insects have rapidly changing energy demands, so they primarily rely on hemolymph and other carbohydrates to carry out life activities. However, how gustatory responsiveness and hemolymph sugar levels coordinate with one another to maintain energetic homeostasis in insects remains largely unknown for the highly social honeybee that goes through large physiological and behavioral changes. The potential role of biogenic amines and neuropeptides in the connection between the regulation of appetite and fluctuating sugar levels in the hemolymph, due to starvation, as the bee ages, was investigated. The largest appetite increase due to the starvation treatment was within the forager age class and this corresponded with an increase in octopamine levels in the brain along with a decline in hemolymph sugar levels. Adipokinetic hormone (AKH) was found in very small quantities in the brain and there were no significant changes in response to starvation treatment. Our findings suggest that the particularly dynamic levels of hemolymph sugar levels may serve as a monitor of the forager honeybee energetic state. Therefore, there may be a pathway in forager bees via octopamine responsible for their precise precipitous regulation of appetite, but to determine cause and effect relationships further investigation is needed.

Mobilization of fat body glycogen and haemolymph trehalose under nutritional stress in Bombyx mori larvae in relation to their physiological age and the duration of food deprivation

In insects, fat body glycogen and haemolymph trehalose are principal carbohydrate reserves. Here, in Bombyx mori (Linnaeus, 1758), we report an accelerated fat body glycogen accumulation in feeding 5th instar larvae, when they reach the terminal growth period (TGP). Haemolymph trehalose and glucose levels, however, fluctuated between 7–21 mM and 0.8–10 mM, respectively, depending on the larval physiological age. Food deprivation triggered a dramatic increase in mobilization of glycogen in larvae at TGP than at active growth period (AGP), mobilized almost 78% of stored glycogen at an initial 12 h of food deprivation, possibly by increasing the percentage of active glycogen phosphorylase, as observed. This rapid glycogen mobilization, along with meeting the energy demand of starving tissues, might also have provided glucose for trehalose synthesis, as evident by observed hypertrehalosemia. A prolonged food deprivation (24–48 h) triggered hypotrehalosemia along with an increase in the enzyme activity of trehalase, and the transcript level of trehalase-2, indicating the utilization of trehalose as an energy source for the demanding tissues. Further, in TGP larvae, a prolonged food deprivation increased the level of haemolymph glucose (1.8–3.5 mM) as well as glucose/trehalose ratio, and this suggests that the fat body might have released the glucose molecules directly into the haemolymph, instead of utilizing it for trehalose synthesis, possibly to minimize the expenditure of energy. Thus, short-term food deprivation triggered an initial glycogen mobilization whereas, prolonged food deprivation led to the utilization of trehalose as an energy source. Hence, mobilization of carbohydrate reserves varied depending on the larval physiological age and the extent of food deprivation period. The future investigation can expand our understanding on the role of glucose as an important haemolymph sugar along with trehalose.

Insulin-like peptides of the legume pod borer, Maruca vitrata, and their mediation effects on hemolymph trehalose level, larval development, and adult reproduction.

Insulin-like peptides (ILPs) of insects mediate various physiological processes including hemolymph sugar level, immature growth, female reproduction, and lifespan. In target cells of ILPs, insulin/insulin-like growth factor signaling (IIS) is highly conserved in animals. IIS in the legume pod borer, Maruca vitrata (Lepidoptera: Crambidae), is known to be involved in maintaining hemolymph trehalose levels and promoting larval growth. However, ILPs in M. vitrata have not been reported yet. This study predicted two ILP genes of Mv-ILP1 and Mv-ILP2 from transcriptome of M. vitrata. Mv-ILP1 and Mv-ILP2 shared high sequence homologies and domain architecture with Drosophila ILPs. Both ILPs exhibited similar expression patterns in most developmental stages, showing high expression levels in adult stage. In the larval stage, Mv-ILP1 and Mv-IlP2 were expressed mostly in the brain and fat body. However, in the adult stage, both ILP genes were expressed more in the abdomen than those in the head containing the brain. RNA interference (RNAi) of either Mv-ILP1 or Mv-ILP2 during larval stage resulted in significant malfunctioning in regulating hemolymph trehalose titers. RNAi-treated larvae also exhibited significant retardation of larval growth. RNAi treatment in adult stage interfered with the ovarian development of females. These results suggest that Mv-ILP1 and Mv-ILP2 play crucial roles in mediating larval growth and adult reproduction.

Intestinal probiotics restore the ecological fitness decline of Bactrocera dorsalis by irradiation.

The sterile insect technique (SIT) as an eco‐friendly and reliable strategy has been used to control populations of insect pests of agricultural, veterinary and human health importance. Successful applications of SIT rely on the high‐level ecological fitness of sterile males. A suitable and stable gut microbiome can contribute to the ecological fitness of insect by influencing their physiology, biochemistry and development processes. Here, we show that a shift in the gut bacterial composition and structure by sterilizing irradiation, characterized by a decrease in the major gut microbiota community Enterobacteriaceae, an expansion of the minor members (e.g., Bacillaceae) and a higher richness and diversity, is tightly linked to radiation‐induced ecological fitness (male mating competitiveness, flight capacity, survival rate and life span) decline in Bactrocera dorsalis (Hendel) sterile males. Function prediction of gut microbiota indicated that changes in microbiome taxonomy tend to drive microbiome functional shifts. A higher nutrient consumption of the flourishing minor gut microbiota may cause a decline in nutrients and energy metabolic activity of host and then result in the reduced ecological fitness of irradiated flies. Furthermore, we found that a gut bacterial strain Klebsiella oxytoca (BD177) can restore ecological fitness by improving food intake and increasing haemolymph sugar and amino acid levels of irradiated B. dorsalis flies. Our findings suggest that gut symbiont‐based probiotics can be used as agents for reversing radiation‐induced ecological fitness decrease.

A modified enzymatic method for measuring insect sugars and the effect of storing samples in ethanol on subsequent trehalose measurements

A modified method for enzymatically measuring concentrations of glucose, fructose and trehalose in parasitoid wasps is described and evaluated. The method has high specificity, gives results comparable to high performance liquid chromatography (HPLC), and shows good correlations with HPLC. The enzymatic method is quicker and less expensive than HPLC, and is safer, faster and more sensitive than another commonly used insect sugar determination method, the anthrone test. The method has potential to measure additional sugars, and details for measuring sucrose are provided as Supplementary material. We also investigate if endogenous enzymes can retain activity in insects preserved in ethanol, thus potentially skewing insect sugar measurements. The results show that the enzyme trehalase, which converts the insect haemolymph sugar trehalose to glucose, can remain active in insect specimens that are stored whole in ethanol. Thus, sugar measurements from insects preserved in this way have potential for bias towards low trehalose and high glucose. In contrast, the activity of endogenous trehalase in insects that are either frozen at −20 °C, or crushed in ethanol is either much reduced or eliminated. If, prior to sugar analysis, insects are to be stored in ethanol at temperatures above −20 °C, then we recommend they be crushed.

Regulation of hemolymph trehalose titers by insulin signaling in the legume pod borer, Maruca vitrata (Lepidoptera: Crambidae)

A disaccharide, trehalose, is a main hemolymph sugar of the legume pod borer, Maruca vitrata larvae, but its titers fluctuated with feeding activity. During diurnal feeding in the photophase, hemolymph trehalose remained at a relatively low level (69 mM) and increased (98 mM) during scotophase. Starvation significantly increased the hemolymph trehalose level, in which the elevation of trehalose titers was dependent on the non-feeding period. The down-regulation of the trehalose level during the active feeding period seemed to result from mediation of the insulin/IGF signal (IIS). Injection of a porcine insulin suppressed the trehalose level in a dose-dependent manner. Genes associated with IIS of M. vitrata were predicted from its larval transcriptome, and their expression was confirmed in different developmental stages and tissues. All seven IIS genes selected were expressed in all developmental stages and different tissues. Silencing of four IIS genes (insulin receptor, Forkhead box O, a serine-threonine protein kinase, target of rapamycin) by RNA interference significantly modulated the hemolymph trehalose level. Starvation treatment changed expression of two trehalose metabolism-associated genes (trehalose phosphate synthase (TPS) and trehalase (TRE)) as well as the IIS genes. Silencing of TPS or TRE expression significantly down- or up-regulated the hemolymph trehalose level, respectively. In addition, silencing of IIS genes altered both TPS and TRE expression, indicating a functional link between IIS and trehalose metabolism. These results suggest that nutrients obtained from feeding activate IIS of M. vitrata, which then down-regulates the hemolymph trehalose level by altering trehalose metabolism.

Antidiabetic effects of novel cell culture established from grapevine, Vitis vinifera cv. Koshu.

Vitis vinifera cv. Koshu is an indigenous cultivar in Japan and has several characteristics that distinguish it from European V. vinifera. In Japan, Koshu is the most popular cultivar for wine making. We report herein a cell culture established from Koshu for use as a system for the production of resveratrol and its derivatives. Grape cell culture YU-1 was developed from the apex tissues of Koshu. YU-1 growth was favorably compared with BY-2 growth, a standard cell line in plant cell biology. Stilbene production and stilbene synthesis gene expression in YU-1 were upregulated by UV-C irradiation. YU-1 irradiated with UV-C decreased hemolymph sugar levels in model animals. Taken together, this study suggests that YU-1 may be used as a source of valuable medicinal components in plant cell bioreactor systems.

Sustenance and Performance: Nutritional Reserves, Longevity, and Contest Outcomes of Fed and Starved Adult Parasitoid Wasps

Dyadic contests for possession of resources occur across a wide range of animal taxa, with contest outcome often being heavily influenced by the energetic reserves of the competitors. The majority of studied parasitoid wasps lack de novo lipogenesis, with adult lipid reserves being limited to those acquired throughout larval development. Carbohydrate- and lipid-rich adult diets can increase adult parasitoid lifespan and fecundity by potentially acting as a maintenance energy store. However, the effects of such diets on fat reserve compositions and some aspects of parasitoid behaviour contest outcome dynamics have not been examined. This study assesses the effect of a carbohydrate rich diet (honey) on the longevity, metabolic state and contest performance of Goniozus legneri, a bethylid wasp. The longevity of honey-fed diet adults was typically more than twice that of starved wasps. Compared to similarly-aged starved wasps, honey feeding increased concentrations of common haemolymph sugars and amino acids in a 3-day old and 7-day old wasps, and higher concentrations of stored lipid in7-day old wasps. However, nutritional status did not affect the outcome of dyadic contests over host possession when both contestants were either 3 days or 7 days old. While contest dynamics outcome may be unaffected by diet, it remains possible that an enhancing effect of feeding on contest ability is matched by an effect of higher value being placed on winning by starved wasps.