scholarly journals The activities of lipases and carnitine palmitoyl-transferase in muscles from vertebrates and invertebrates

1972 ◽  
Vol 130 (3) ◽  
pp. 697-705 ◽  
Author(s):  
B. Crabtree ◽  
E. A. Newsholme
Keyword(s):  
Insect Flight ◽  
Glycerol Kinase ◽  
O2 Uptake ◽  
Carnitine Palmitoyl Transferase ◽  
Fat Utilization ◽  
Metabolic Role ◽  
Intact Muscle ◽  
Flight Muscles ◽  
Hydrolysis Of

1. The activities of tri-, di- and mono-glyceride lipase and carnitine palmitoyltransferase were measured in homogenates of a variety of muscles. These activities were used to estimate the rate of utilization of glycerides and fatty acids by muscle. In muscles whose estimated rates of fat utilization can be compared with rates calculated for the intact muscle from such information as O2 uptake, there is reasonable agreement between the estimated and calculated rates. 2. In all muscles investigated the maximum rates of hydrolysis of glycerides increase in the order triglyceride, diglyceride, monoglyceride. The activity of diglyceride lipase is highest in the flight muscles of insects such as the locust, waterbug and some moths and is lowest in the flight muscles of flies, bees and the wasp. These results are consistent with the utilization of diglyceride as a fuel for some insect flight muscles. 3. In many muscles from both vertebrates and invertebrates the activity of glycerol kinase is similar to that of lipase. It is concluded that in these muscles the metabolic role of glycerol kinase is the removal of glycerol produced during lipolysis. However, in some insect flight muscles the activity of glycerol kinase is much greater than that of lipase, which suggests a different role for glycerol kinase in these muscles.

scholarly journals Validamycin A Delays Development and Prevents Flight in Aedes aegypti (Diptera: Culicidae)

2020 ◽  
Vol 57 (4) ◽  
pp. 1096-1103 ◽  
Author(s):  
Andrew D Marten ◽  
Alicyn I Stothard ◽  
Karishma Kalera ◽  
Benjamin M Swarts ◽  
Michael J Conway
Keyword(s):  
Aedes Aegypti ◽  
Insect Flight ◽  
Chitin Synthesis ◽  
Pupal Development ◽  
Validamycin A ◽  
Disease Vector ◽  
Regulation Of Metabolism ◽  
Hydrolysis Of ◽  
Important Disease

Abstract Trehalose is a disaccharide that is the major sugar found in insect hemolymph fluid. Trehalose provides energy, and promotes growth, metamorphosis, stress recovery, chitin synthesis, and insect flight. The hydrolysis of trehalose is under the enzymatic control of the enzyme trehalase. Trehalase is critical to the role of trehalose in insect physiology, and is required for the regulation of metabolism and glucose generation. Trehalase inhibitors represent a novel class of insecticides that have not been fully developed. Here, we tested the ability of trehalose analogues to function as larvacides or adulticides in an important disease vector—Aedes aegypti. We show that validamycin A, but not 5-thiotrehalose, delays larval and pupal development and prevents flight of adult mosquitoes. Larval mosquitoes treated with validamycin A were hypoglycemic and pupae had increased levels of trehalose. Treatment also skewed the sex ratio toward male mosquitoes. These data reveal that validamycin A is a mosquito adulticide that can impair normal development of an important disease vector.

scholarly journals The effects of calcium ions on the activities of trehalase, hexokinase, phosphofructokinase, fructose diphosphatase and pyruvate kinase from various muscles

1973 ◽  
Vol 132 (3) ◽  
pp. 527-535 ◽  
Author(s):  
H. Vaughan ◽  
S. D. Thornton ◽  
E. A. Newsholme
Keyword(s):  
Pyruvate Kinase ◽  
Insect Flight ◽  
Supernatant Fraction ◽  
Glycolytic Flux ◽  
Insect Muscle ◽  
Regulatory Enzymes ◽  
Flight Muscles ◽  
Cell Fractions ◽  
Regulatory Properties

1. The effects of Ca2+ on the activities and regulatory properties of trehalase, hexokinase, phosphofructokinase, fructose diphosphatase and pyruvate kinase from vertebrate red and white muscle and insect fibrillar and non-fibrillar muscle have been investigated. These muscles were selected because of the possible difference in the role of glycolysis in energy production in the vertebrate muscles, and the possible difference in the role of Ca2+ in the control of contraction in the two types of insect muscle. An increase in Ca2+ concentration from 0.001μm to 10μm did not modify the activities nor did it modify the regulatory properties of these enzymes from these various muscles. 2. Concentrations of Ca2+ above 0.1mm inhibited the activities of hexokinase and phosphofructokinase from the different muscles. It has been suggested that this inhibition may provide the basis for a theory of regulation of glycolysis (Margreth et al., 1967). If phosphofructokinase is located within the sarcoplasmic reticulum, its activity will be inhibited when the muscle is at rest, but the release of Ca2+ from the reticulum during contraction will lead to a stimulation of its activity and hence an increase in glycolytic flux. The distribution of hexokinase and phosphofructokinase in the various cell fractions of these muscles was very variable. In particular, both enzymes were present almost exclusively in the 100000g supernatant fraction in the extracts of insect flight muscles. Thus there is no correlation between the properties of the enzymes and their distribution in muscle. 3. It is concluded that Ca2+ does not control the activities of the important regulatory enzymes of glycolysis in muscle. It is suggested that in some muscles the sensitivity of the control mechanism at the level of phosphofructokinase to changes in the concentration of AMP may be increased by a process known as `substrate-cycling'.

scholarly journals The activities of fructose diphosphatase in flight muscles from the bumble-bee and role of this enzyme in heat generation

1972 ◽  
Vol 128 (1) ◽  
pp. 89-97 ◽  
Author(s):  
E. A. Newsholme ◽  
B. Crabtree ◽  
S. J. Higgins ◽  
S. D. Thornton ◽  
Carole Start
Keyword(s):  
Flight Muscle ◽  
Maximum Activity ◽  
The Body ◽  
Bumble Bee ◽  
Rest Periods ◽  
Flight Muscles ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Hydrolysis Of ◽  
Low Activity

1. The maximum catalytic activities of fructose diphosphatase from flight muscles of bumble-bees (Bombus spp.) are at least 30-fold those reported for the enzyme from other tissues. The maximum activity of fructose diphosphatase in the flight muscle of any particular bee is similar to that of phosphofructokinase in the same muscle, and the activity of hexokinase is similar to or greater than the activity of phosphofructokinase. There is no detectable activity of glucose 6-phosphatase and only a very low activity of glucose 6-phosphate dehydrogenase in these muscles. The activities of both fructose diphosphatase and phosphofructokinase vary inversely with the body weight of the bee, whereas that of hexokinase is relatively constant. 2. There is no significant hydrolysis of fructose 1-phosphate, fructose 6-phosphate, glucose 1,6-diphosphate and glycerol 3-phosphate by extracts of bumble-bee flight muscle. 3. Fructose 1,6-diphosphatase from bumble-bee flight muscle and from other muscles is inhibited by Mn2+and univalent cations; the potency of inhibition by the latter varies in the order Li+>Na+>K+. However, the fructose diphosphatase from bumble-bee flight muscle is different from the enzyme from other tissues in that it is not inhibited by AMP. 4. The contents of ATP, hexose monophosphates, fructose diphosphate and triose phosphates in bumble-bee flight muscle showed no significant changes between rest and flight. 5. It is proposed that both fructose diphosphatase and phosphofructokinase are simultaneously active and catalyse a cycle between fructose 6-phosphate and fructose diphosphate in resting bumble-bee flight muscle. Such a cycle would produce continuous hydrolysis of ATP, with the release of energy as heat, which would help to maintain the thoracic temperature during rest periods at a level adequate for flight.

scholarly journals Histopathological Features of Symptomatic and Asymptomatic Honeybees Naturally Infected by Deformed Wing Virus

Pathogens ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 874
Author(s):  
Karen Power ◽  
Manuela Martano ◽  
Gennaro Altamura ◽  
Nadia Piscopo ◽  
Paola Maiolino
Keyword(s):  
Viral Load ◽  
Asymptomatic Group ◽  
Deformed Wing Virus ◽  
Stage Of Development ◽  
Pathogenic Action ◽  
Degenerative Alterations ◽  
Flight Muscles ◽  
Asymptomatic Individuals ◽  
Histopathological Results

Deformed wing virus (DWV) is capable of infecting honeybees at every stage of development causing symptomatic and asymptomatic infections. To date, very little is known about the histopathological lesions caused by the virus. Therefore, 40 honeybee samples were randomly collected from a naturally DWV infected hive and subjected to anatomopathological examination to discriminate between symptomatic (29) and asymptomatic (11) honeybees. Subsequently, 15 honeybee samples were frozen at −80° and analyzed by PCR and RTqPCR to determinate the presence/absence of the virus and the relative viral load, while 25 honeybee samples were analyzed by histopathological techniques. Biomolecular results showed a fragment of the expected size (69bp) of DWV in all samples and the viral load was higher in symptomatic honeybees compared to the asymptomatic group. Histopathological results showed degenerative alterations of the hypopharyngeal glands (19/25) and flight muscles (6/25) in symptomatic samples while 4/25 asymptomatic samples showed an inflammatory response in the midgut and the hemocele. Results suggest a possible pathogenic action of DWV in both symptomatic and asymptomatic honeybees, and a role of the immune response in keeping under control the virus in asymptomatic individuals.

scholarly journals Steroid Sulphatase and Its Inhibitors: Past, Present and Future

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2852
Author(s):  
Paul A. Foster
Keyword(s):  
Good Evidence ◽  
The Past ◽  
Steroid Sulphatase ◽  
University Of Oxford ◽  
Therapeutic Value ◽  
Breast And Prostate Cancer ◽  
The University ◽  
Further Development ◽  
Hydrolysis Of

Steroid sulphatase (STS), involved in the hydrolysis of steroid sulphates, plays an important role in the formation of both active oestrogens and androgens. Since these steroids significantly impact the proliferation of both oestrogen- and androgen-dependent cancers, many research groups over the past 30 years have designed and developed STS inhibitors. One of the main contributors to this field has been Prof. Barry Potter, previously at the University of Bath and now at the University of Oxford. Upon Prof. Potter’s imminent retirement, this review takes a look back at the work on STS inhibitors and their contribution to our understanding of sulphate biology and as potential therapeutic agents in hormone-dependent disease. A number of potent STS inhibitors have now been developed, one of which, Irosustat (STX64, 667Coumate, BN83495), remains the only one to have completed phase I/II clinical trials against numerous indications (breast, prostate, endometrial). These studies have provided new insights into the origins of androgens and oestrogens in women and men. In addition to the therapeutic role of STS inhibition in breast and prostate cancer, there is now good evidence to suggest they may also provide benefits in patients with colorectal and ovarian cancer, and in treating endometriosis. To explore the potential of STS inhibitors further, a number of second- and third-generation inhibitors have been developed, together with single molecules that possess aromatase–STS inhibitory properties. The further development of potent STS inhibitors will allow their potential therapeutic value to be explored in a variety of hormone-dependent cancers and possibly other non-oncological conditions.

scholarly journals METABOLIC ROLE OF THE PYRIMIDINE-3 LOCUS OF NEUROSPORA

Genetics ◽  
1965 ◽  
Vol 52 (4) ◽  
pp. 829-834
Author(s):  
Dina Finck ◽  
Yoshitaka Suyama ◽  
Rowland H Davis
Keyword(s):  
Metabolic Role

scholarly journals Regulation of the synthesis and hydrolysis of ATP by mitochondrial ATPase. Role of Mg2+.

1983 ◽  
Vol 258 (22) ◽  
pp. 13673-13679 ◽  
Author(s):  
A Gómez-Puyou ◽  
G Ayala ◽  
U Muller ◽  
M Tuena de Gómez-Puyou
Keyword(s):  
Mitochondrial Atpase ◽  
Hydrolysis Of

The role of pretreatment in improving the enzymatic hydrolysis of lignocellulosic materials

2016 ◽  
Vol 199 ◽  
pp. 49-58 ◽  
Author(s):  
Shaoni Sun ◽  
Shaolong Sun ◽  
Xuefei Cao ◽  
Runcang Sun
Keyword(s):  
Enzymatic Hydrolysis ◽  
Lignocellulosic Materials ◽  
Hydrolysis Of
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