Hemolymph Glucose Levels Research Articles

Oxidative stress in abalone: The role of temperature, oxygen and l-proline supplementation

In their natural distribution range and in on land-based mariculture facilities, Haliotis midae may be exposed to a relatively wide range of temperatures and oxygen levels, that can induce differential degrees of stress with concomitant metabolic responses.In the current study juvenile H. midae were exposed for one month to two constant temperatures (14°C and 19°C), with three oxygen levels (82%, 98% and 126% oxygen saturation) at each temperature. One additional treatment was included at 19°C, 126% oxygen, where feed was supplemented with l-proline. The results presented here suggest that long-term 19°C exposure is more stressful to H. midae juveniles than a 14°C exposure of the same duration, since exposure to higher temperature generally resulted in higher activities of the antioxidant enzymes measured but lower total antioxidant capacities. Haemolymph glucose levels responded to oxygen treatment at the 14°C exposure, but the same response was not initiated in the 19°C treatment, possibly because the animals exposed to the 19°C treatment relied on proteins to a larger extent.Increased oxygen levels at the 19°C treatment did not cause more DNA damage or protein carbonylation compared to lower oxygen levels. Supplementing feed with l-proline at the high temperature/high oxygen treatment caused a decrease in haemolymph haemocyanin (which may exhibit catalase function) content and a slight decrease in some of the antioxidant enzyme activities, while maintaining the same total antioxidant capacity compared with the same treatment where feed was not supplemented. The overall DNA integrity profile also changed with proline-supplementation, as did the induction level of hsp70. When projecting tissue growth over a 12month period under these conditions, we estimate that H. midae juveniles in this study may exhibit a significant increase in mass when their feed was supplemented with l-proline, indicating that l-proline supplementation provides some benefit to the individual. It might therefore warrant conducting long-term growth trials on land-based mariculture facilities to further investigate its potential benefit to the mariculture industry.

Seasonal and gender-related differences in morphometric features and cellular and biochemical parameters of Carcinus aestuarii from the Lagoon of Venice

In this study, the seasonal variations in the morphometric features and in the cellular and biochemical parameters of the haemolymph were investigated in both male and female crabs (Carcinus aestuarii). Crabs were seasonally (November 2010–August 2011) collected from the Lagoon of Venice, and the moult stage, weight, width and length of the carapace, and width and length of the bigger chela were evaluated. In addition, the total haemocyte count (THC), haemocyte diameter and volume, haemolymph glucose and total protein levels, and haemolymph phenoloxidase (PO) and N-acetyl-β-glucosaminidase (NAG) activities were measured. The results demonstrated that the collected crabs were all in the intermoult stage and that the males were bigger than the females. A two-way ANOVA revealed a significant effect of season on the THC and the haemocyte volume and a significant influence of gender on the haemocyte diameter. Season and gender significantly affected the haemolymph glucose concentration, whereas haemolymph protein levels were dependent only on the season. In addition, both season and gender significantly influenced the PO and NAG activities in the haemolymph. Overall, the results demonstrated that crab morphometric features as well as haemolymph cellular and biochemical parameters varied markedly as a function of both season and gender.

Biological, biochemical and histopathological features related to parasitic castration of Biomphalaria glabrata infected by Schistosoma mansoni

Parasitic castration in the snail-trematode relationship can be understood as any change in the reproductive function of the snail that is due to interference by the developing larvae inside the snail that leads to the reduction or complete disruption of egg-laying activity. This study was designed to observe the parasitic castration of Biomphalaria glabrata infected with Schistosoma mansoni during both the pre-patent and patent periods. The effect of infection on snail fecundity and fertility, growth rate and survival was studied during the 62 days following miracidia exposure. An integrated approach was employed that used biochemical and histological tools over the same period. To study the effect of infection on reproduction, we individually exposed 30 snails to 5 miracidia each and tracked their fertility and fecundity. For our histopathological studies, 50 snails were exposed to 20 miracidia each, and for our histochemical studies, 50 snails were exposed to 5 miracidia each. An equal number of uninfected snails were used as a control for each group. The B. glabrata exposed to the BH strain of S. mansoni showed 50% positivity for cercarial shedding. Both the experimental and control groups showed 100% survival. The pre-patent period lasted until 39 days after exposure to miracidia. Exposed snails that showed cercarial shedding exhibited higher growth rates than either exposed snails that did not demonstrate cercarial shedding or uninfected controls. Exposed snails without cercarial shedding and uninfected controls showed no differences in the reproductive parameters evaluated during the patent period; snails experiencing cercarial shedding showed a reduction in fecundity and fertility. These snails began to lay eggs only after the 50th day post miracidia exposure. The haemolymph glucose levels showed an oscillating pattern that decreased during periods of greater mobilisation of energy by the larvae and was accompanied by a depletion of glycogen in the cephalopodal mass and digestive gland. Histopathological examination at 55 days showed that the ovotestis was highly atrophied. There was almost complete disappearance of germ cells, and the supporting stroma formed a nearly empty net. At day 45, the infected digestive gland showed a high cylindrical epithelium with little preserved cytoplasm. The contents of the secretory granules of the albumen gland of infected animals stained with Alcian blue (AB), pH 1.0, indicating the presence of sulphated carbohydrates. Thus, parasitic castration in the B. glabrata-S. mansoni model may be regulated directly and indirectly by the developmental stage of the trematode and the biochemical and histopathological alterations during the patent period of infection.

Neuroendocrine responses of a crustacean host to viral infection: Effects of infection of white spot syndrome virus on the expression and release of crustacean hyperglycemic hormone in the crayfish Procambarus clarkii

The objectives of the present study were to characterize the changes in crustacean hyperglycemic hormone (CHH) transcript and peptide levels in response to infection of white spot syndrome virus (WSSV) in a crustacean, Procambarus clarkii. After viral challenge, significant increase in virus load began at 24h post injection (hpi) and the increase was much more substantial at 48 and 72hpi. The hemolymph CHH levels rapidly increased after viral challenge; the increase started as early as 3hpi and lasted for at least 2d after the challenge. In contrast, the hemolymph glucose levels did not significantly changed over a 2 d period in the WSSV-infected animals. The CHH transcript and peptide levels in tissues were also determined. The CHH transcript levels in the eyestalk ganglia (the major site of CHH synthesis) of the virus-infected animals did not significantly change over a 2 d period and those in 2 extra-eyestalk tissues (the thoracic ganglia and cerebral ganglia) significantly increased at 24 and 48hpi. The CHH peptide levels in the eyestalk ganglia of the virus-infected animals significantly decreased at 24 and 48hpi and those in the thoracic ganglia and cerebral ganglia remained unchanged over a 2 d period. These data demonstrated a WSSV-induced increase in the release of CHH into hemolymph that is rapid in onset and lasting in duration. Changes in the CHH transcript and peptide levels implied that the WSSV-induced increase in hemolymph CHH levels primarily resulted from an enhanced release from the eyestalk ganglia, but the contribution of the 2 extra-eyestalk tissues to hemolymph pool of CHH increased as viral infection progressed. The combined patterns of change in the hemolymph glucose and CHH levels further suggest that the virus-enhanced CHH release would lead to higher glycolytic activity and elevated glucose mobilization presumably favorable for viral replication.

A chimeric recombinant crustacean hyperglycemic hormone fromLitopenaeus schmitti(Burkenroad) obtained as C-terminus fusion protein boost hemolymph glucose concentration inLitopenaeus vannamei(Boone)

To date, no hormonal treatments are available for control of shrimp reproduction and only eyestalk ablation is of practical use. The crustacean hyperglycemic hormone (CHH) is the most abundant neuropeptide of the eyestalk CHH family. It plays an important role in the regulation of hemolymph glucose levels, as its principal function, but it is also implicated in additional physiological processes such as moulting and reproduction. In the present study, the cDNA encoding Litopenaeus schmitti (Burkenroad) mature CHH was cloned into the Escherichia coli pTYB2 expression vector. Using this strategy we have obtained, for the first time, the recombinant CHH from L. schmitti with its C-terminus fused to an intein tag. The expected fused protein of about 63 KDa was expressed in E. coli forming inclusion bodies. It was purified in a soluble form by electroelution following molecular size fractionation in sodium dodecil sulphate polyacrylamide gel electrophoresis. The ability of the chimeric CHH protein to elevate glucose levels in the hemolymph of the eyestalk-ablated Litopenaeus vannamei (Boone) shrimps indicates that its biological activity as hyperglycemic protein is preserved. The results provide an alternative tool to obtain soluble recombinant proteins from the CHH family of neuropeptides to get a better understanding of shrimp endocrinology.

EFEITO DA TEMPERATURA E DOS ALIMENTOS PROTÉICO E LIPÍDICO NOS ESTÁDIOS DE MATURAÇÃO OVARIANA E ESTÁGIOS DE MUDA DO Macrobrachium acanthurus (WIEGMANN, 1836)

Knowing the reproductive physiology of the prawn Macrobrachium acanthurus in relation to controlled factors, such as processed food and temperature variations, would help to develop culture techniques, assuring its survival. Aiming at the finding some data on this subject, females of M. acanthurus were submitted to the effect of three temperatures (20, 25 and 30oC) and three types of food (lipidic, proteic and commercial). Following this procedure, the effects of haemolymph glucose, total protein and total lipid levels on ovarian maturation as well as in the moulting stages were analyzed. Results showed that nutrient levels usually increased as the animals reached D stage and the temperature increased. The nutrient levels also increased as animals reached stage III of ovarian maturation. Glucose and total protein levels increased with increasing temperature, while total lipid levels diminished at 30oC. Lipid food produced an increase in the haemolymph glucose and total proteins, while lipid and commercial food produced an increase in total lipids. In spite of that, results showed no significant differences among moulting stages and ovarian maturation, when measured at the same temperature.KEYWORDS: glucose; haemolymph; physiology; total lipid; total protein.

Effects of cadmium on carbohydrate and protein metabolisms in the freshwater crab Sinopotamon yangtsekiense

The physiological impact of Cd2+ on Sinopotamon yangtsekiense was evaluated through changes of selected parameters considered as key elements of carbohydrate and protein metabolisms. Crab were exposed to 0.725, 1.45, 2.9mg·L−1 Cd2+ for 7, 14 and 21days. A time- and/or concentration- dependent decrease in muscle glycogen and increase in LDH activity suggested that glycolysis was accelerated during the treatments. Increased protease activity, lowering of FAA and the initially increased and subsequently decreased aminotransferase activities suggest an enhanced protein mobilization during early Cd2+ exposure followed by a metabolic impairment during late exposure. Decreased hemolymph glucose level was observed in the crabs treated with 2.9mg·L−1 Cd2+ for 21d, suggesting an impaired gluconeogenesis. Ammonia level barely changed during the 14d Cd2+ exposure most likely due to the increased urea and glutamine production; After 1.45 and 2.9mg·L−1 Cd2+ treatment for 21d, ammonia was observed increased followed by an exclusive increase in glutamine. Taken together, our results indicate that carbohydrate and protein are mobilized to a varying degree as a compensatory metabolism to response to the energy stress during acute Cd2+ exposure. As the time lapsed, some symptoms on metabolism obstacle reflect the toxic effect of sublethal Cd2+.

Glucose metabolism in the hepatopancreas of the crab Neohelice granulata maintained on carbohydrate-rich or high-protein diets: Anoxia and recovery

The effects of 1-h anoxia and 3-h recovery periods were assessed on hepatopancreatic glucose metabolism in the crab Neohelice granulata fed on either a carbohydrate-rich (HC) or high-protein (HP) diet. Anoxia increased pyruvate kinase (PK) and hexokinase (HK) activities in HC-fed animals, coinciding with a decrease in glycogen levels. No significant changes occurred in glucose uptake and glycogen synthesis in either dietary group. In HP-fed crabs, HK activity decreased and PK activity was 40% lower than that found in the HC-fed group after anoxia. Also, anoxia decreased 14CO 2 production, ATP and glycogen levels in hepatopancreas in both groups. During recovery, hemolymph glucose levels decreased in both groups but glucose uptake remained constant. In the HP group, the increase in glycogen synthesis represents an important fate of glucose during recovery from anoxia. In HC-fed crabs, the hepatopancreas glycolytic pathway is involved in the post-anoxia fate of glucose.

Effects of crustacean hyperglycemic hormone (CHH) on the transcript expression of carbohydrate metabolism-related enzyme genes in the kuruma prawn, Marsupenaeus japonicus

Crustacean hyperglycemic hormone (CHH), a member of a neuropeptide family present only in arthropods, plays a pivotal role in the modulation of hemolymph glucose levels, molting, reproduction, and the stress response. Although it has been determined that hepatopancreas and muscle are the major tissues in which CHH regulates hyperglycemic activity, the molecular mechanism by which CHH regulates carbohydrate metabolism remains unclear. In this study, we analyzed the mRNA expression levels of enzymes involved in glycogen metabolism and gluconeogenesis in order to determine how CHH regulates hemolymph glucose levels. We first cloned cDNAs encoding four carbohydrate metabolism-related enzymes from the kuruma prawn, Marsupenaeus japonicus, glycogen phosphorylase (MjGP), glycogen synthase (MjGS), fructose 1,6-bisphosphatase (MjFBPase), and phosphoenolpyruvate carboxykinase (MjPEPCK). RT-PCR analysis showed that eyestalk ablation remarkably decreased MjGP and increased MjGS transcript levels in the hepatopancreas, but not in muscle. Considering the fact that various eyestalk factors, including MIH, are removed by eyestalk ablation, these results indicate that after eyestalk ablation the metabolic state proceeds towards glycogen accumulation in the specific tissues related to molting. In contrast, MjFBPase and MjPEPCK transcript levels were not significantly changed by eyestalk ablation, indicating that CHH and other eyestalk-derived factors might not induce gluconeogenesis. Quantitative real-time PCR analysis showed that exposure of hepatopancreas to recombinant CHH significantly changed the expression levels of MjGP and MjGS, but not MjFBPase and MjPEPCK. Collectively, these results indicate that CHH is involved in glycogen metabolism in hepatopancreas.

Can starvation influence cellular and biochemical parameters in the crab Carcinus aestuarii?

Crustacea experience periods of starvation during moulting or when limited food availability occurs. The effects of starvation on Crustacea physiological responses have been demonstrated, whereas the effects of starvation on Crustacea immune parameters remain to be more fully studied. In the present study the effects of starvation on immune parameters and antioxidant enzyme activities of the crab Carcinus aestuarii were evaluated for the first time. Treated crabs were starved for 7 days, whereas control crabs were fed daily with mussels. Total haemocyte count (THC), haemocyte diameter and volume, haemocyte proliferation, cell-free haemolymph (CFH) glucose and total protein levels, and phenoloxidase (PO) activity in both haemocyte lysate (HL) and CFH were measured in crabs. In addition, superoxide dismutase (SOD) and catalase (CAT) activities were evaluated in both gills and digestive gland from crabs, in order to evaluate whether starvation induced oxidative stress in C. aestuarii. THC increased significantly in starved crabs, with respect to controls, whereas no significant variations were observed in haemocyte diameter, volume and proliferation. In CFH of starved animals glucose concentration significantly increased, whereas total protein concentration significantly reduced. A significantly higher PO activity was recorded in HL from starved crabs, than in control crabs. Conversely, PO activity did not vary significantly in CFH. Starvation did not cause significant alterations in antioxidant enzyme activities in both gills and digestive gland. Results obtained demonstrated that starvation influenced crab immune parameters, but did not induce oxidative stress. Results also indicated that C. aestuarii can modulate its cellular and biochemical parameters in order to cope with starvation.

Expression and applications of recombinant crustacean hyperglycemic hormone from eyestalks of white shrimp ( Litopenaeus vannamei) against bacterial infection

Crustacean hyperglycemic hormone (CHH) has many functions to regulate carbohydrate metabolism, ecdysis and reproduction including ion transport in crustaceans. The cDNA encoding CHH peptides containing 369 bp open reading frame encoding 122 amino acids was cloned from eyestalk of white shrimp ( Litopenaeus vannamei) and was produced by a bacterial expression system. The biological activity of recombinant L. vannamei crustacean hyperglycemic hormone (rLV-CHH) was tested. The hemolymph glucose level of shrimp increased two-fold at 1 h after the rLV-CHH injection and then returned to normal after 3 h. In addition to the effect of rLV-CHH administration (25 μg/shrimp) on immunological responses of white shrimp against pathogenic bacteria, Vibrio harveyi was studied. Results showed that the blood parameters of shrimp injected with rLV-CHH; the THC, PO activity, serum protein level and clearance ability to V. harveyi, were also higher than those of Neg-protein and PBS-injected shrimp. The survival of shrimp injected with rLV-CHH was significantly higher (66.0%) than shrimp that injected with Neg-protein (33.3%) and PBS (28.9%) after 14 days. It is possible that the administration of rLV-CHH in L. vannamei exhibited a higher immune response related to resistance against V. harveyi infection.

Cellular and biochemical parameters in the crab Carcinus aestuarii after experimentally-induced stress: Effects of bacterial injection, leg ablation and bacterial injection/leg ablation combination

The effects of bacterial injection, leg ablation and bacterial injection/leg ablation combination on cellular and biochemical parameters of the crab Carcinus aestuarii were evaluated. Total haemocyte count (THC), haemocyte volume, haemocyte proliferation, phenoloxidase (PO) activity in both haemocyte lysate (HL) and cell-free haemolymph (CFH) and CFH glucose levels were used as biomarkers of stress in crabs. After 24h following bacterial injection, no significant variation in THC were observed, whereas haemocyte diameter and volume decreased significantly in injected crabs with respect to controls. Haemocyte proliferation and glucose levels increased significantly in injected crabs, whereas no significant variations in PO activity was recorded between control and injected crabs. THC increased significantly one-day after leg ablation, whereas it decreased significantly after 3 and 7days. Haemocyte diameter and volume did not vary significantly between control and de-clawed crabs at each sampling times. In de-clawed crabs, haemocyte proliferation was significantly higher after 7days, whereas glucose and PO activity increased significantly in CFH after 1 and 3days. The bacterial injection/leg ablation combination caused a statistically significant decrease in both THC and haemocyte diameter and volume, whereas increased significantly glucose levels in CFH. Overall, results obtained demonstrated that stress conditions investigated in the present study affected both cellular and biochemical parameters in C. aestuarii. Results also indicated that crabs can cope with differing stressful conditions modulating their immune parameters depending on the kind of stress undergone. Although preliminary, our results may explain – partially at least – the great adaptability and widespread of C. aestuarii out of its native area.

Cadmium and mercury-induced hyperglycemia in the fresh water crab, Oziotelphusa senex senex: Involvement of neuroendocrine system

The effect of exposure to sublethal concentrations of cadmium chloride and mercuric chloride on hemolymph glucose levels of the freshwater crab, Oziotelphusa senex senex, was studied. Intact crabs exposed to cadmium or mercury exhibited a significant hyperglycemia compared to controls, but no significant differences in hemolymph glucose level were detected among the eyestalkless crabs after exposure to metals, suggesting that the effect of metals could be on the sinus gland in the eyestalks, increasing secretion of the hyperglycemic hormone. To test this hypothesis, eyestalks were collected from control and metal exposed crabs, and tested for hyperglycemic effect and also for the hyperglycemic hormone levels. The levels of hyperglycemic hormone and the hyperglycemic effect were significantly low in the eyestalks collected from metal exposed crabs when compared with eyestalks from control crabs. These results strongly suggest that metals act, at least in part, by triggering the secretion of hyperglycemic hormone from the eyestalk.

Isolation and characterization of an additional crustacean hyperglycemic hormone from the greasyback shrimp Metapenaeus ensis

Crustacean hyperglycemic hormone (CHH) is released from the X-organ/sinus gland complex located in the eyestalks. In this study, the most abundant CHH in the sinus gland of the greasyback shrimp Metapenaeus ensis was purified by reversed-phase HPLC and identified by N-terminal amino acid sequencing. Although two CHH molecules (Mee-CHH-A and Mee-CHH-B) have already been identified from M. ensis by cDNA cloning, this study revealed the presence of an additional CHH peptide based on differences in the N-terminal amino acid sequences of the CHH-A and CHH-B. Therefore, this novel CHH was designated as Mee-CHH-C. A cDNA encoding the Mee-CHH-C precursor was cloned by RT-PCR coupled with 5′- and 3′-RACE, and it was found that the mature Mee-CHH-C consisted of 72 amino acid residues containing 6 conserved cysteine residues and possessed an amidated C terminus. Mee-CHH-C had 62 and 68% identities with Mee-CHH-A and Mee-CHH-B, respectively, and was highly homologous to CHHs characterized from other penaeid shrimp species. The hyperglycemic activity of Mee-CHH-C was examined by an in vivo bioassay using the kuruma prawn Marsupenaeus japonicus. Injection of Mee-CHH-C increased hemolymph glucose levels significantly and dose-dependently. These results indicate that Mee-CHH-C is possibly one of the major molecules in M. ensis that regulate glucose levels in the hemolymph.

Effects of crustacean hyperglycemic hormone (CHH) on carbohydrate metabolism-related enzymes in the kuruma prawn, Marsupenaeus japonicus

Event Abstract Back to Event Effects of crustacean hyperglycemic hormone (CHH) on carbohydrate metabolism-related enzymes in the kuruma prawn, Marsupenaeus japonicus Chiaki Nagai1*, Hideaki Mabashi-Asazuma2, Junpei Shinji1 and Hiromichi Nagasawa1 1 The University of Tokyo, Department of Applied Biological Chemistry, Japan 2 The University of Wyoming, Department of Molecular Biology, United States In crustaceans, eyestalk ablation causes various physiological events, including decrease of the hemolymph glucose level by lacking of a neuropeptide, crustacean hyperglycemic hormone (CHH). Although the hyperglycemic activity of CHH is well documented, little has been investigated on its functional regulation at a molecular level. In this study, to clarify the mechanism of the regulation, we analyzed the effects of CHH on glycogen metabolism and gluconeogenesis. We first cloned cDNAs encoding four carbohydrate metabolism-related enzymes; glycogen phosphorylase (MjGP), glycogen synthase (MjGS), fructose 1,6-bisphosphatase (MjFBPase), and phosphoenolpyruvate carboxykinase (MjPEPCK) from Marsupenaeus japonicus by degenerate PCR, and then analyzed their expression levels by RT-PCR. The results showed that eyestalk ablation two days before the experiment decreased the mRNA level of MjGP, while this treatment increased that of MjGS in a main tissue for glycogen storage, hepatopancreas as well as in other tissues, indicating that the eyestalk-ablated prawns declined to the metabolic condition for glycogen accumulation. On the other hand, little changes in the levels of MjFBPase and MjPEPCK were observed, indicating that hypoglycemic condition caused by eyestalk ablation might not be due to hormonal regulation via gluconeogenesis. We next analyzed the mRNA levels of the four enzymes in the hepatopancreas and muscle by ex vivo stimulation of CHH. Quantative RT-PCR analyses showed that the mRNA levels of these enzymes in the examined tissues did not change after 1 hour exposure to 100 nM CHH, indicating that carbohydrate metabolism may not be transcriptionally regulated by CHH at least in a short period. Keywords: comparative endocrinology Conference: 25th Conference of the European Comparative Endocrinologists, Pécs, Hungary, 31 Aug - 4 Sep, 2010. Presentation Type: Conference Presentation Topic: Comparative endocrinology Citation: Nagai C, Mabashi-Asazuma H, Shinji J and Nagasawa H (2010). Effects of crustacean hyperglycemic hormone (CHH) on carbohydrate metabolism-related enzymes in the kuruma prawn, Marsupenaeus japonicus. Front. Endocrinol. Conference Abstract: 25th Conference of the European Comparative Endocrinologists. doi: 10.3389/conf.fendo.2010.01.00048 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 26 Aug 2010; Published Online: 29 Aug 2010. * Correspondence: Ms. Chiaki Nagai, The University of Tokyo, Department of Applied Biological Chemistry, Tokyo, Japan, chi-a-ki@dg8.so-net.ne.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Chiaki Nagai Hideaki Mabashi-Asazuma Junpei Shinji Hiromichi Nagasawa Google Chiaki Nagai Hideaki Mabashi-Asazuma Junpei Shinji Hiromichi Nagasawa Google Scholar Chiaki Nagai Hideaki Mabashi-Asazuma Junpei Shinji Hiromichi Nagasawa PubMed Chiaki Nagai Hideaki Mabashi-Asazuma Junpei Shinji Hiromichi Nagasawa Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Natural variation in plasticity of glucose homeostasis and food intake

Balancing the acquisition, allocation and storage of energy during periods of food deprivation is critical for survival. We show that natural variation in the foraging (for) gene, which encodes a cGMP-dependent protein kinase (PKG) in the fruit fly Drosophila melanogaster, affects behavioral and physiological responses to short-term food deprivation. Rover and sitter, natural allelic variants of for, differ in their stored carbohydrate reserves as well as their response to short-term deprivation. Fewer carbohydrates are stored in the fat body of rovers compared with sitters, and more labeled glucose is allocated to lipid stores compared with carbohydrate stores during a short feeding bout. Short-term food deprivation decreases hemolymph glucose levels in rovers but not in sitters. After food deprivation, rovers increase their food intake more slowly than sitters, and rover hemolymph levels take longer to respond to re-feeding. Finally, rovers have lower adipokinetic hormone (akh) mRNA levels than sitters. Our data suggest that for mediates larval responses to short-term food deprivation by altering food intake and blood glucose levels.

A convenient method for preparation of biologically active recombinant CHH of the kuruma prawn, Marsupenaeus japonicus, using the bacterial expression system

Crustacean hyperglycemic hormone (CHH) not only plays an important role in the modulation of hemolymph glucose level but also functions in other biological events including molting, reproduction and stress response. Of the six CHHs characterized in Marsupenaeus japonicus, an expression system for recombinant Pej-SGP-VII (rPej-SGP-VII-amide) has not yet been established. Here, we established a procedure using a Nus-tag for solubilization, thereby soluble and biologically active rPej-SGP-VII-amide could successfully be obtained by a simpler procedure than previous ones used for producing other recombinant Pej-SGPs (Pej-SGP-I, III and IV). It was found that rPej-SGP-VII-amide thus obtained had the correct arrangement of intramolecular disulfide bonds and helix-rich secondary structure. The established expression system for rPej-SGP-VII-amide may be applicable for the preparation of other recombinant CHHs.

Effect of retinoic acid on hemolymph glucose regulation in the fresh water edible crab Oziotelphusa senex senex

9- cis-Retinoic acid (9CRA) and all- trans-retinoic acid (ATRA) are known to be involved in the regulation of glucose homeostasis in vertebrates by inducing insulin release and expression of glucose reporter proteins. In view of the fact that 9CRA and ATRA are endogenous in crustaceans and a retinoic acid X-receptor exists in crabs, we investigated whether 9CRA and ATRA also plays a role in glucose homeostasis in freshwater crab, Oziotelphusa senex senex. Injection of 9CRA into intact crabs significantly increased the hemolymph glucose level in a dose-dependent manner. Such 9CRA-induced hyperglycemia was apparently mediated by the CHH since injection of 9CRA into eyestalk-ablated crabs did not result in hyperglycemia. In support of this, administration of 9CRA in to crabs resulted in reduced hyperglycemic activity of eyestalks and elevated titers of CHH in hemolymph. ATRA injection did not cause any changes in hemolymph glucose and CHH levels. The results provide the first evidence that 9- cis-retinoic acid, but not all- trans-retinoic acid, is involved in the regulation of glucose homeostasis and apparently mediated by the eyestalk hormone CHH.

Effect of insulin/IGF-I like peptides on glucose metabolism in the white shrimp Penaeus vannamei

The insulin-like hormone superfamily encompasses insulin, relaxin, and insulin-like growth factors I (IGF1) and II (IGF2). Insulin hormones regulate cell growth, metabolism, and tissue-specific functions. The presence of insulin has been demonstrated in various invertebrates, and their function as growth promoting or controlling factors has been established in molluscs and insects. In crustaceans, the presence of insulin/insulin-like growth factor (IGF)-like peptides has also been suggested and functional studies have been associated with metabolic control. The general aim of the current study was to elucidate the functional significance of insulin-like peptides in the white shrimp Penaeus vannamei. Because the primary structure of Penaeus insulin is yet unknown, we examined the effect of mammalian insulin/IGF-I on glucose metabolism in P. vannamei. Juvenile shrimps were injected with a single dose of recombinant human (rh) IGF-I or bovine insulin in intermolt stage. Glucose/glycogen levels in shrimp hemolymph and tissues (muscle, hepatopancreas and gills) were determined over a 5 h period by means of an enzymatic analysis. We showed that an injection of rhIGF-I induced a significant ( P < 0.01) increase in glucose levels in hemolymph, 1 h after injection and followed by a decrease ( P < 0.05) 5 h post-injection. In the hepatopancreas, an increase ( P < 0.05) in the glycogen content was observed 3 h after insulin treatment. Finally, a significant elevation ( P < 0.01) of glycogen content in the gills throughout the entire sampling period was detected. Our study suggests the presence of endogenous Penaeus insulin(s) that, just like its vertebrate counterparts, is likely to be involved in the regulation of carbohydrate metabolism in crustaceans.

Effect of serotonin on hemolymph glucose regulation in the fresh water edible crab Oziotelphusa senex senex

One of the well known crustacean hormones is the crustacean hyperglycemic hormone (CHH). However, the mechanisms involved in the release of this hormone into circulation are poorly studied. The fresh water crabs Oziotelphusa senex senex were injected with serotonin and hemolymph glucose and CHH levels were determined. Injection of serotonin into intact crabs caused significant hyperglycemia in a dose-dependent manner. Administration of serotonin also caused a significant increase in the circulatory levels of CHH. In contrast, injection of serotonin did not cause any change in hemolymph glucose level in eyestalk ablated crabs. The results confirm that serotonin induced hyperglycemia was apparently mediated by the eyestalk hormone CHH.