A comparison of the properties of the pyruvate kinases of the fat body and flight muscle of the adult male desert locust.
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ABSTRACT:
SUBMITTER: Bailey E
PROVIDER: S-EPMC1187519 | biostudies-other | 1969 Feb
REPOSITORIES: biostudies-other
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Project description:1. Phosphofructokinase was isolated, and partially purified by ammonium sulphate fractionation, from the fat body and flight muscle of the desert locust. 2. Ammonium sulphate appears to stabilize the enzymes, but does not activate them. 3. Both flight-muscle and fat-body enzymes give sigmoidal hexose monophosphate concentration-activity curves, which are characteristic of regulatory enzymes. 4. At low ATP concentrations both the enzyme activities increase rapidly with increasing ATP concentrations, but above an optimum concentration ATP becomes inhibitory. This optimum concentration is 0.2mm for the fat-body enzyme and 0.1mm for the flight-muscle enzyme. 5. AMP activates both the enzymes; half-maximal activation occurs at 10mum in each case, the effect being independent of substrate concentration. 6. 3',5'-(cyclic)-AMP (0.5mm) and P(i) (1mm) activate the flight-muscle enzyme, but have no effect on the fat-body enzyme. 7. FDP (1mm) inhibits both enzymes, and with the flight-muscle enzyme this inhibition is increased by increasing the ATP concentration. 8. Citrate, phosphoenolpyruvate and alpha-glycerophosphate have no effect on either enzyme under the assay conditions used. 9. The properties of phosphofructokinases from the locust are compared with those of phosphofructokinases from other sources.
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Project description:1. Glycogen phosphorylase of locust fat-body was partially purified by differential centrifugation and dissociation from glycogen particles at two pH values. 2. Optimum activity was obtained at pH6.6-6.7. 3. The calculated apparent K(m) values for glycogen and glucose 1-phosphate were 0.08% and 10-13mm respectively. 4. 5'-AMP activated in the range 5mum-1mm. 5. Glucose 6-phosphate is a competitive inhibitor for the substrate glucose 1-phosphate (K(i)=1.7mm). 5'-AMP abolishes this inhibition. Glucose weakly inhibits (K(i)=25-30mm), but trehalose does not inhibit even at 100mm. 6. It is suggested that glucose 6-phosphate is a major regulator of glycogen phosphorylase activity in locust fat-body.
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Project description:Background: Hypoxia can affect aerobic organisms profoundly. Biological responses to extreme hypoxia have been well studied. However, it is not well characterized how living organisms respond to mild hypoxia, and how they distinguish different levels of hypoxia. Results: We examined the transcriptional responses of locusts using microarrays to reveal their strategies to cope with mild hypoxia. Mitochondrial activities were systemically suppressed, mainly involving energy production and mitochondrial biogenesis. The functions of endoplasmic reticulum were activated to clear the dysfunctional proteins and rescue newly synthesized proteins. Glucose in cytosol was shunted from glycolysis to pentose phosphate pathway probably to tackle the oxidative stress by enhancing the production of reductive forces. Conclusions: Locusts’ responses to mild hypoxia differ from that to severe hypoxia . In severe hypoxia, glucose resources are shunted to glycolysis to produce ATP and tackle energy crisis; however, in mild hypoxia, they are diverted to produce reductive forces and deal with oxidative stress. Locusts are capable of distinguishing different levels of hypoxia and initiating proper defenses.
2012-12-12 | GSE33898 | GEO
Project description:The involvement of associative learning cues has been demonstrated in several stages of feeding and food selection. Short neuropeptide F (sNPF), an insect neuropeptide whose effects on feeding behavior have previously been well established, may be one of the factors bridging feeding and learning behavior. Recently, it was shown in Drosophila melanogaster that the targeted reduction of Drome-sNPF transcript levels significantly reduced sugar-rewarded olfactory memory. While Drosophila mainly relies on olfactory perception in its food searching behavior, locust foraging behavior is likely to be more visually orientated. Furthermore, a feeding-dependent regulation of Schgr-sNPF transcript levels has previously been observed in the optic lobes of the locust brain, suggesting a possible involvement in visual perception of food and visual associative memory in this insect species. In this study, we describe the development of a robust and reproducible assay allowing visual associative memory to be studied in the desert locust, Schistocerca gregaria. Furthermore, we performed an exploratory series of experiments, studying the role of Schgr-sNPF in this complex process.
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Project description:Background: Hypoxia can affect aerobic organisms profoundly. Biological responses to extreme hypoxia have been well studied. However, it is not well characterized how living organisms respond to mild hypoxia, and how they distinguish different levels of hypoxia. Results: We examined the transcriptional responses of locusts using microarrays to reveal their strategies to cope with mild hypoxia. Mitochondrial activities were systemically suppressed, mainly involving energy production and mitochondrial biogenesis. The functions of endoplasmic reticulum were activated to clear the dysfunctional proteins and rescue newly synthesized proteins. Glucose in cytosol was shunted from glycolysis to pentose phosphate pathway probably to tackle the oxidative stress by enhancing the production of reductive forces. Conclusions: LocustsM-bM-^@M-^Y responses to mild hypoxia differ from that to severe hypoxia . In severe hypoxia, glucose resources are shunted to glycolysis to produce ATP and tackle energy crisis; however, in mild hypoxia, they are diverted to produce reductive forces and deal with oxidative stress. Locusts are capable of distinguishing different levels of hypoxia and initiating proper defenses. Simulated 4km altitude hypoxia treatment vs. normoxia control;direct comparison on 6 separate microarrays; each microarray compares one biological replicate of treatment and control; each biological replicate contains 10 individuals
2012-12-12 | E-GEOD-33898 | biostudies-arrayexpress
Project description:The female locust lays its eggs deep within soft substrate to protect them from predators and provide optimal conditions for successful development and hatching. During oviposition digging, the female's abdomen is pooled and extends into the ground, guided by a dedicated excavation mechanism at its tip, comprising two pairs of specialized digging valves. Little is known about how these active valves negotiate the various obstacles encountered on their path. In this study, female locusts oviposited their eggs in specialized sand-filled tubes with pre-inserted 3D-printed plastic obstacles. The subterranean route taken by the abdomen and digging valves upon encountering the obstacles was investigated, characterized, and compared to that in control tubes without obstacles. Data were obtained by way of visual inspection, by utilizing cone beam computed tomography scans in high-definition mode, and by making paraffin casts of the oviposition burrows (after egg hatching). We demonstrate, for the first time, the subterranean navigation ability of the female locust's excavation mechanism and its ability to circumvent obstacles during oviposition. Finally, we discuss the role of active sensory-motor mechanisms versus the passive embodied function of the valves, central control, and decision-making.
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Project description:DNA methylation is a widely conserved epigenetic modification that is established and maintained by the cooperative activity of DNA methyltransferases. While the complement of DNA methyltransferase genes can vary substantially between animal species, whole-genome methylation analyses have suggested that major features of animal methylomes are widely conserved. We have now used genome-scale bisulfite sequencing to analyze the methylome of the desert locust, Schistocerca gregaria, which represents an economically important pest with a high degree of phenotypic plasticity. Interestingly, in this system, DNA methylation appears to be both established and maintained by Dnmt1 methyltransferases, which distinguishes locusts from most other known organisms. Our results indicate that the S. gregaria methylome shares preferential methylation of CpG dinucleotides and exons with other animal methylomes. In contrast to other invertebrates, however, overall methylation levels were substantially higher and a significant fraction of transposons was methylated. Additionally, genes were densely methylated in a pronounced bimodal pattern, suggesting a role for DNA methylation in the regulation of locust gene expression. Altogether, our results uncover a unique pattern of genome methylation in locusts and also suggest that animal methylomes may be more diverse than previously thought.
2013-05-03 | GSE41214 | GEO
Project description:In desert locusts, increased population densities drive phenotypic transformation from the solitarious to the gregarious phase within a generation [1-4]. Here we show that when presented with odor-food associations, the two extreme phases differ in aversive but not appetitive associative learning, with solitarious locusts showing a conditioned aversion more quickly than gregarious locusts. The acquisition of new learned aversions was blocked entirely in acutely crowded solitarious (transiens) locusts, whereas appetitive learning and prior learned associations were unaffected. These differences in aversive learning support phase-specific feeding strategies. Associative training with hyoscyamine, a plant alkaloid found in the locusts' habitat [5, 6], elicits a phase-dependent odor preference: solitarious locusts avoid an odor associated with hyoscyamine, whereas gregarious locusts do not. Remarkably, when solitarious locusts are crowded and then reconditioned with the odor-hyoscyamine pairing as transiens, the specific blockade of aversive acquisition enables them to override their prior aversive memory with an appetitive one. Under fierce food competition, as occurs during crowding in the field, this provides a neuroecological mechanism enabling locusts to reassign an appetitive value to an odor that they learned previously to avoid.
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Project description:Studies of mating and reproductive behavior have contributed much to our understanding of various animals' ecological success. The desert locust, Schistocerca gregaria, is an important agricultural pest. However, knowledge of locust courtship and precopulatory behavior is surprisingly limited. Here we provide a comprehensive study of the precopulatory behavior of both sexes of the desert locust in the gregarious phase, with particular emphasis on the conflict between the sexes. Detailed HD-video monitoring of courtship and mating of 20 locust pairs, in a controlled environment, enabled both qualitative and quantitative descriptions of the behavior. A comprehensive list of behavioral elements was used to generate an eight-step ethogram, from first encounter between the sexes to actual copulation. Further analyses included the probability of each element occurring, and a kinematic diagram based on a transitional matrix. Eleven novel behavioral elements are described in this study, and two potential points of conflict between the sexes are identified. Locust sexual interaction was characterized by the dominance of the males during the pre-mounting stage, and an overall stereotypic male courtship behavior. In contrast, females displayed no clear courtship-related behavior and an overall less organized behavioral sequence. Central elements in the sexual behavior of the females were low-amplitude hind-leg vibration, as well as rejecting males by jumping and kicking. Intricate reciprocal interactions between the sexes were evident mostly at the mounting stage. The reported findings contribute important insights to our knowledge of locust mating and reproductive behavior, and may assist in confronting this devastating agricultural pest.
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