Evidence for dissolved glucose uptake from seawater by Neocalanus plumchrus (Arthropoda, Copepoda)

Autoradiographic techniques indicate that Neocalanus plumchrus is capable of removing labelled glucose from seawater at concentrations as low as 2.3 × 10−9 M. Uptake is via dermal glands and midgut. Consequent glucose transfer occurs through haemocoel to muscles and germinal tissue.

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Glucose partitioning in the pregnant ewe: Effects of undernutrition and exercise

British Journal Of Nutrition ◽

10.1079/bjn19900045 ◽

1990 ◽

Vol 64 (2) ◽

pp. 449-462 ◽

Cited By ~ 20

Author(s):

B. J. Leury ◽

A. R. Bird ◽

K. D. Chandler ◽

A. W. Bell

Keyword(s):

Glucose Uptake ◽

Energy Requirement ◽

Live Weight ◽

Late Pregnancy ◽

Maternal Blood ◽

Whole Body ◽

Entry Rate ◽

Glucose Transfer ◽

Glucose Supply ◽

Maternal Glucose

Maternal whole-body glucose entry rate and uterine and umbilical net uptakes of glucose and oxygen were measured in single-pregnant ewes which were either well-fed throughout, or fed at 0.3–0.4 predicted energy requirement for 7–21 d during late pregnancy. All ewes were studied while standing at rest and then while walking on a treadmill at 0.7 m/s on a 10° slope for 60 min. Underfed ewes suffered significant decreases in live weight and had lower fetal, but not placental, weights at 140–144 d gestation. Undernutrition also caused large decreases in maternal glycaemia and glucose entry rate, which were associated with equally large decreases in uterine and umbilical net uptakes and O2 quotients of glucose, and with a decrease in placental glucose transfer capacity. Exercise caused increases in maternal blood concentration, entry rate and uterine net uptake of glucose, the magnitudes of which were not significantly affected by plane of nutrition. Umbilical glucose uptake and placental glucose transfer capacity increased during exercise in underfed but not fed ewes. The fractional distribution of maternal glucose to the pregnant uterus, and of uterine glucose uptake to the fetus, were unaltered by undernutrition; during exercise, a disproportionately small fraction of the increased maternal glucose supply went to the uterus. The results confirm that the ovine conceptus responds to nutritional reduction in maternal glucose availability in a manner similar to non-uterine maternal tissues. Major reductions in glucose supply appear to override putative glucose-sparing mechanisms which may operate to favour the conceptus in better-nourished animals.

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Placental-fetal glucose exchange and placental glucose consumption in pregnant sheep

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1990.258.2.e360 ◽

1990 ◽

Vol 258 (2) ◽

pp. E360-E367 ◽

Cited By ~ 6

Author(s):

J. E. DiGiacomo ◽

W. W. Hay

Keyword(s):

Glucose Uptake ◽

Glucose Concentration ◽

Insulin Infusion ◽

Glucose Utilization ◽

Glucose Clamp ◽

Utilization Rate ◽

Base Line ◽

Glucose Transfer ◽

Pregnant Sheep ◽

Maternal Glucose

To determine the separate effects of changes in fetal glucose and insulin concentrations on uteroplacental glucose transfer (UPGT) and consumption (UPGC) we studied 24 late-gestation pregnant sheep during fetal insulin infusions alone and with simultaneous glucose clamp. Insulin infusion alone increased fetal glucose utilization rate (GUR) by 45% (P less than 0.001), decreasing fetal glucose concentration by 40% (P less than 0.01) and thereby increasing fetal glucose clearance (Clglu) by 150% (P less than 0.001). Maternal-fetal glucose gradient also increased, resulting in a 40% increase (P less than 0.02) in UPGT [measured as umbilical glucose uptake (UGU)] and a 30% decrease (P less than 0.05) in UPGC. Addition of a fetal glucose clamp returned fetal glucose concentration to base line and restored UPGC and UGU to control values with a further 2.25-fold increase in fetal GUR. Clglu did not change, as the increase in GUR was proportional to the increase in fetal glucose concentration. Similarly, in animals receiving an insulin infusion plus glucose clamp throughout, maternal glucose concentration, fetal glucose concentration, UPGC, and UGU did not change, whereas GUR and Clglu increased approximately 1.9-fold. These changes were noted at constant maternal glucose concentration and uterine glucose uptake. Thus variation in fetal glucose concentration rather than fetal insulin concentration directly regulates uteroplacental glucose transfer and consumption, whereas both fetal insulin and glucose affect, in separate ways, fetal glucose utilization and clearance.

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The Dermal Glands of Rhodnius Prolixus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100063202 ◽

1969 ◽

Vol 27 ◽

pp. 258-259

Author(s):

J. E. Lai-Fook

Keyword(s):

Fine Structure ◽

Secretory Activity ◽

Rhodnius Prolixus ◽

Outermost Layer ◽

Cement Layer ◽

Dermal Glands

Dermal glands are epidermal derivatives which are reported to secrete either the cement layer, which is the outermost layer of the epicuticle or some component of the moulting fluid which digests the endocuticle. The secretions do not show well-defined staining reactions and therefore they have not been positively identified. This has contributed to another difficulty, namely, that of determining the time of secretory activity. This description of the fine structure of the developing glands in Rhodnius was undertaken to determine the time of activity, with a view to investigating their function.

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Two isoprenylated flavonoids from Dorstenia psilurus activate AMPK, stimulate glucose uptake, inhibit glucose production and lower glycemia

Biochemical Journal ◽

10.1042/bcj20190326 ◽

2019 ◽

Vol 476 (24) ◽

pp. 3687-3704 ◽

Cited By ~ 2

Author(s):

Aphrodite T. Choumessi ◽

Manuel Johanns ◽

Claire Beaufay ◽

Marie-France Herent ◽

Vincent Stroobant ◽

...

Keyword(s):

Glucose Uptake ◽

Human Cancer ◽

Glucose Production ◽

Liver Mitochondria ◽

New Drugs ◽

Structural Isomer ◽

Rat Liver Mitochondria ◽

Ionization Mass ◽

Ampk Activation ◽

Starting Point

Root extracts of a Cameroon medicinal plant, Dorstenia psilurus, were purified by screening for AMP-activated protein kinase (AMPK) activation in incubated mouse embryo fibroblasts (MEFs). Two isoprenylated flavones that activated AMPK were isolated. Compound 1 was identified as artelasticin by high-resolution electrospray ionization mass spectrometry and 2D-NMR while its structural isomer, compound 2, was isolated for the first time and differed only by the position of one double bond on one isoprenyl substituent. Treatment of MEFs with purified compound 1 or compound 2 led to rapid and robust AMPK activation at low micromolar concentrations and increased the intracellular AMP:ATP ratio. In oxygen consumption experiments on isolated rat liver mitochondria, compound 1 and compound 2 inhibited complex II of the electron transport chain and in freeze–thawed mitochondria succinate dehydrogenase was inhibited. In incubated rat skeletal muscles, both compounds activated AMPK and stimulated glucose uptake. Moreover, these effects were lost in muscles pre-incubated with AMPK inhibitor SBI-0206965, suggesting AMPK dependency. Incubation of mouse hepatocytes with compound 1 or compound 2 led to AMPK activation, but glucose production was decreased in hepatocytes from both wild-type and AMPKβ1−/− mice, suggesting that this effect was not AMPK-dependent. However, when administered intraperitoneally to high-fat diet-induced insulin-resistant mice, compound 1 and compound 2 had blood glucose-lowering effects. In addition, compound 1 and compound 2 reduced the viability of several human cancer cells in culture. The flavonoids we have identified could be a starting point for the development of new drugs to treat type 2 diabetes.

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