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Results for “Locusta migratoria”

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PubMed1975

[Effect of injection of synthetic Hyalophora cecropia juvenile hormone in Locusta migratoria L].

The synthetic racemic C18 Hyalophora cecropia juvenile hormone (JH-I) is injected at does of between 10 and 200 mug/animal at the end of the fourth instar of Locusta migratoria. The effects on mortality, length of the fourth and fifth instars, pigmentation and morphogenesis are reported. Higher doses of JH-I produce a higher mortality than lower doses. But mortality can also occur following the injection of oil which sometimes takes place only a few hours before the ecdysis. In no case is JH-I able to shorten the length of the instar. Many animals moult at the same time as the controls, but some of them, both in the fourth and fifth instars, show an important increase in the length of the instar because of an inhibition of the ecdysis. The effect of JH-I on pigmentation is very important and doses higher than 50 mug/animal present a greater effect than an implantation of one pair of corpora allata, both on the number of insects which turn green and on the intensity of this green pigmentation. At the metamorphosis the larvae injected with JH-I produce imperfect imagos and supernumerary larvae, the number of which depends upon the dose. Nevertheless the morphogenetic effect is considerably lower than that of one pair of corpora allata. We have reason to think that this is only due to the time of injection and not to the activity on morphogeneis of the injected hormone. JH-I is injected at the dose of 200 mug in young females which were allatectomized beforehand to prevent oocytes maturation. The hormone completely counter-balances the lack of the corpora allata and some days after the injection the oocytes are in the same state of development as those of the controls. All the results indicate that the synthetic racemic C18 juvenile hormone of Hyalophora cecropia shows a quite similar activity to the secretion of the corpora allata on Locusta migratoria although it has been said for some time that this hormone was not the principal one in locusts.

Animals↗

PubMed1994

Partial identification, synthesis and immunolocalization of locustamyoinhibin, the third myoinhibiting neuropeptide isolated from Locusta migratoria.

A blocked neuropeptide that suppresses the motility of the cockroach hindgut has been isolated from an extract of 9000 brain-corpora cardiaca-corpora allata-suboesophageal ganglion complexes of Locusta migratoria. Biological activity was monitored during HPLC purification by observing the myoinhibiting activity of column fractions on the isolated hindgut of Leucophaea maderae. Due to the low amount of material left after deblocking, this myoinhibiting peptide--designated as locustamyoinhibin or Lom-MIH--could only be partially sequenced: pGlu-X-Tyr-X'-Lys-Gln-Ser-Ala-Phe-Asn-Ala-Val-Ser-NH2. Nevertheless, the carboxy-terminal nonamer sequence (Lom-MIH5-13) was synthesized and also displayed myoinhibiting activity, indicating that the biologically active core lies in the carboxy-terminal sequence. Lom-MIH shows no sequence similarities with other peptides from vertebrate or invertebrate sources and is the third myoinhibiting peptide identified in Locusta migratoria. A polyclonal antiserum was raised against Lom-MIH5-13 and used to investigate the distribution of immunoreactive peptide in the central nervous system and its associated neurohaemal structures. Two groups of neurons with somata in the optic lobes show locustamyoinhibin (Lom-MIH)-like immunoreactivity. These groups have somata at the dorsal and ventral edge of the lamina ganglionaris. The neurons have dense ramifications in the lamina, with processes extending into the first optic chiasma and into the accessory medulla. Four cell bodies were detected in the protocerebrum, and two cells were found at the externo-lateral edge of the tritocerebrum. No immunoreactive perikarya could be observed in the suboesophageal ganglion nor in the ganglia of the ventral nerve cord. Neither the corpora cardiaca nor the neurohaemal organs of the ventral nerve cord showed immunolabelling. Therefore, our findings provide anatomical evidence for a central neurotransmitter role of Lom-MIH.

Amino Acid Sequence↗

PubMed2003

Biochemical characterization and bacterial expression of an odorant-binding protein from Locusta migratoria.

Analysis of soluble proteins from different body parts of Locusta migratoria revealed a fast-migrating component in native electrophoresis, unique to antennae of both sexes. N-terminal sequence analysis and cloning identified this protein as a member of the insect odorant-binding proteins, carrying a well-conserved six-cysteine motif. Mass spectrometry analysis confirmed the occurrence of two distinct polypeptide species determined by nucleotide sequencing and demonstrated that the cysteine residues are paired in an interlocked fashion. The protein was expressed in a bacterial system with yields of about 10 mg/l of culture, mostly present as inclusion bodies. However, this recombinant product was solubilized after disulfide reduction. Air oxidation yielded a species with all disulfides spontaneously formed as in the native counterpart. Both native and recombinant proteins migrated as a dimer in gel filtration chromatography. Ligand binding was measured, using N-phenyl-1-naphthylamine as the fluorescent probe; the affinity of other ligands was measured in competitive binding assays. The protein exhibited great resistance to thermal denaturation even following prolonged treatment at 100 degrees C. A structural model for this dimeric species was generated on the basis of its sequence homology with Bombyx mori pheromone-binding protein, whose three-dimensional structure has been resolved as an unbound species and in complex with its physiological ligand. This is the first report of an odorant-binding protein identified and characterized from Orthoptera.

Amino Acid Sequence↗

PubMed1992

Insect immunity: two proteinase inhibitors from hemolymph of Locusta migratoria.

Two protease inhibitors were isolated from the plasma of Locusta migratoria and sequenced. They were 35 and 36 amino acids long and revealed very little similitude for the protease inhibitors isolated from other arthropods. They inhibit the proPhenoloxidase Phenoloxidase proteolytic activation cascade in hemocyte extracts of the same insect. This inhibiting activity resulted in a lower production of PO, a key enzyme for the defence mechanism in arthropods. Both peptides however showed a strong in vitro inhibiting activity toward alpha-chymotrypsin and elastase, LMCI I inhibits the human leukocyte enzyme while LMCI II mostly the pancreatic one, a difference explainable on the basis of the active site sequence changes.

Amino Acid Sequence↗

PubMed1997

Second messenger-controlled membrane conductance in locust (Locusta migratoria) olfactory neurons.

The membrane conductance of olfactory neurons of Locusta migratoria was examined using the whole-cell configuration of the patch-clamp technique. Intracellular application of the second messenger inositol 1,4,5 trisphosphate (IP(3)) via a dual pipette technique elicited a clear increase in the membrane conductance. The IP(3)-induced conductance increased due to a rise in the extracellular concentration of calcium from 100&mgr;M to 4mM. Micromolar concentrations of ruthenium red partially blocked the IP(3)-induced increase in membrane conductance. Stimulating olfactory neurons with odour (hexenoic acid) resulted in an increase in the membrane conductance partially similar to that mediated IP(3). These findings suggest that stimulation with appropriate odours as well as intracellular application of IP(3) activate the same calcium-permeable ion channels in the plasma membrane of insect olfactory neurons.

Journal Article↗

PubMed2001

Feeding state influences the content of FMRFamide- and tachykinin-related peptides in endocrine-like cells of the midgut of Locusta migratoria.

The midgut of 5th instar male African migratory locust, Locusta migratoria, was found to contain endocrine-like cells that stained positively for FMRFamide-like immunoreactivity. These cells have cell bodies which are tear-drop in shape with processes extending from the cell body. FMRFamide-like immunoreactivity has been described in similar cells in adult midgut tissue [16]. The midgut tissue content of FMRFamide-like immunoreactivity is differentially distributed throughout various regions of the midgut (gastric cecae, anterior and posterior midgut) in 5th instar and varied ages of adult. FMRFamide-like immunoreactivity in midgut tissues decreases significantly by 24 h of starvation, whereas locustatachykinin I-like immunoreactivity does not decrease until 48 h of starvation indicating that there are differential timing effects of these two peptide families on midgut content. HPLC analysis, combined with RIA, of different regions of the midgut tissue from both fed and starved locusts revealed that the relative proportions of the members of the two peptide families vary depending upon the feeding state. These results indicate that the contents of these endocrine-like cells appears to be differentially influenced by the feeding state of the locust.

Animals↗

PubMed2002

Characterization of a putative SchistoFLRFamide receptor in the CNS of Locusta migratoria.

A putative SchistoFLRFamide receptor in CNS membrane preparations of Locusta migratoria was characterized by cold competition binding and kinetic binding assays using [125I][Y(1)]SchistoFLRFamide ([125I]YDVDHVFLRFamide) as a radioligand. Binding to this site was saturable, specific, reversible, and of high-affinity. Data fit to a single-site binding model by non-linear regression (r(2) = 0.99) estimated K(d) = 1.73 +/- 0.45 x 10(-9) M and B(max) = 49.0 +/- 12.2 fmol.mg(-1) tissue. Total binding of [125I][Y(1)]SchistoFLRFamide to membrane preparations was reduced in the presence of GTPgammaS, an indication that the putative receptor is G protein-coupled. Structure-activity studies determined that the minimum sequence required for binding was HVFLRFamide. Other aspects of the ligand receptor interaction were also examined.

Animals↗

PubMed1979

[Synthesis of juvenile hormones in vitro by the corpora allata of 5th stage larva of Locusta migratoria migratorioides (R and F) (Insecta, Orthopteroida)].

Corpora allata of Locusta migratoria 5th stage larvae synthesize J.H.1, J.H.2 and J.H.3 in vitro. The C.A. of insects of different ages exbit different rates of J.H. synthesis. J.H.1 and J.H.2 synthesis is less than 1 ng/48 h/gland. During the same time the J.H.3 production may be as much as 25.6 ng/gland. J.H. synthetic activity is the same between right and left C.A. The release of J.H. from the C.A. occurs immediately following synthesis. These results are compared with in vivo haemolymphatic J.H. levels.

Animals↗

PubMed1992

Immunocytochemical localization of Bombyx-PTTH-like molecules in neurosecretory cells of the brain of the migratory locust, Locusta migratoria. A comparison with neuroparsin and insulin-related peptide.

Using a monoclonal antibody directed against a synthetic pentadecapeptide corresponding to the N-terminus of the prothoracicotropic hormone (PTTH) of Bombyx mori, we report the presence of immunoreactive molecules in a large number of median neurosecretory cells of the pars intercerebralis of the migratory locust, Locusta migratoria. These cells correspond to the A1 cell type which we show to contain also neuroparsins, a family of predominant neurohormones of the migratory locust. In contrast, PTTH-like molecules are absent from A2 cells of the pars intercerebralis which contain Locusta insulin-related peptide (LIRP). Developmental studies show the presence of PTTH-related substances in neurosecretory cells of Locusta migratoria from late embryogenesis to adult development, including ageing vitellogenic female adults.

Amino Acid Sequence↗

PubMed1977

The ultrastructure of an olfactory sensillum on the maxillary palps of locusta migratoria (L.).

The olfactory sensilla on the maxillary palp tip of Locusta migratoria (L.) resemble the surrounding contact chemoreceptors in general morphology. The perforated peg has a thicker wall than is commonly found in olfactory sensilla. The form and position of the sensilla are considered in relation of the olfactory function. The fine structure of the dendrites is discussed in relation to that described in other olfactory sensilla.

Animals↗

PubMed2004

The influence of diet and feeding state on FMRFamide-related peptides in the gut of Locusta migratoria L.

Gut tissues of 2-week post-ecdysis female Locusta migratoria L. were assayed for FMRFamide-like immunoreactivity (FLI) during various feeding states using both radioimmunoassay and immunohistochemistry. The feeding states investigated were: (a) 48- and 24-h starved; (b) 5-, 30-, or 60-min post-feeding initiation; and (c) a diet of wheat grass, carrots, or apples. We determined: (1) the feeding state of a locust influences FLI in all gut tissues; (2) variations in diet appear to influence FLI in all gut tissues; (3) more than one FMRFamide-related peptide (FaRP) responds to differences in diet and state of starvation in the gut tissues; and (4) the protein poor diets (carrot and apple), in conjunction with the assertion that protein to carbohydrate ratio in the diet is the key component for nutrient balancing, suggests that FaRPs may play a role in maintaining balanced nutrient content in the locust.

Animals↗

PubMed2003

Inhibition of fungal growth in thermoregulating locusts, Locusta migratoria, infected by the fungus Metarhizium anisopliae var acridum.

The locust, Locusta migratoria, has the capacity to develop a behavioural fever which reduces fungal infection by Metarhizium anisopliae var acridum. We investigated hemocyte and blastospore kinetics in infected insects under conditions that did or did not allow thermoregulation. Hemocyte concentrations were severely reduced in inoculated insects that did not thermoregulate but remained similar to those of controls in inoculated insects that were allowed to thermoregulate. Reductions in hemocyte counts were accompanied by an increase in the concentration of blastospores. In non-thermoregulating insects, circulating blastospores were first observed two days post-inoculation and had heavily colonized the hemolymph by day 5; in contrast, no blastospores were recovered from hemolymph of inoculated-thermoregulating insects. We used fluorescein isothiocyanate (FITC)-labelled silica beads to examine in vivo phagocytosis in thermoregulating and non-thermoregulating locusts. In the absence of fungus, a greater proportion of beads were engulfed by hemocytes in thermoregulating than in non-thermoregulating locusts early (4 and 24h) after bead injection, but the proportions were similar thereafter. In infected locusts, phagocytosis in non-thermoregulating insects was progressively impaired; such impairment, however, was not observed in challenged, thermoregulating insects. Our results suggest that thermoregulation helped keep fungal growth in check, apparently through the maintenance of hemocyte population levels and the direct inhibition of blastospore propagation by elevated temperatures.

Animals↗

PubMed2000

Characterisation of multiple trypsins from the midgut of Locusta migratoria.

Three isoforms of trypsin were identified in midgut preparations from Locusta migratoria. Ammonium-sulphate-fractionated luminal contents of midguts were subjected to benzamidine affinity chromatography; proteins eluted by benzamidine were then separated by anion-exchange chromatography. Cationic (TRY 1) and anionic (TRY 2) trypsin activities were eluted from the DEAE column. TRY 1 was homogeneous, producing a single band of Mr 23,000 on SDS-PAGE. TRY 2 comprised two trypsins, TRY 2A (Mr 27,000) and TRY 2B (Mr 29,000). Following a subsequent chromatography step using a Bio-Rad UNO Q column, TRY 2A and TRY 2B were resolved to homogeneity. When homogenates of midgut caecae were the starting material for chromatography, SDS-PAGE of benzamidine-eluted proteins revealed an additional putative trypsin of Mr 17,000 (termed SERP 17) which had been absent from luminal enzyme preparations. Determination of the N-terminal 11 amino acid residues of each protein revealed unique, but similar sequences. The four sequences all began with IVGG, a motif which signifies all four proteins are serine proteases. TRY 1, TRY 2A and TRY 2B were shown to contain only trypsin activity and the preparations were sensitive to inhibition by AEBSF, PMSF, TLCK, benzamidine, leupeptin, SBTI, BPTI and E64.

Amino Acid Sequence↗

PubMedDate not supplied

[Ultrastructural organization of the anterior sensory neuropile in the metathoracic ganglion of the locust Locusta migratoria].

The study of serial sections of the metathoracic ganglion of Locusta migratoria showed that the fibres of the tympanal nerve terminate in the dorsal half of the anterior sensory neuropile (ASN). Three types of synaptic endings were found in the ASN. Endings type I contain dense-core vesicles 600-850 A in diameter, more or less uniformly distributed in the axoplasm. They do not form specialized contacts with postsynaptic fibres and are localized only in the most ventral part of the ASN. Endings type II contain clear round vesicles 400-450 A in diameter (rare 250-300 A) and form typical synapses with dense pre-and postsynaptic membranes and synaptic cleft 150-200 A. Four types of contacts formed by these endings with postsynaptic fibres were found: 1 : 1 synapses; convergent, divergent and serial. All of them are well presented in the auditory neuropile. Endings type III contain both dense-core and clear vesicles in different relation. Only clear vesicles of these endings are connected with the active sites of the membrane.

Animals↗

PubMedDate not supplied

[Physiological features of the wing muscle fibers of Locusta migratoria locusts].

In bifunctional dorsoventral muscle M-120 of the locust Locusta migratoria migratorioides three groups of fibers have been found which differ with respect to their electrophysiological properties. The evoked fast potentials in the fibers of caudal portion differed from fast potentials observed in the fibers of rostral and intermediate portions of the muscle. In the fibers of the caudal and intermediate portions of muscle, not only fast, but other depolarization potentials were also recorded which differ in the amplitude and duration, as well as the inhibitory postsynaptic potentials. It was shown that fibers in these three parts of the muscle differ in their voltage-current properties. It is concluded that different types of potentials are due to peculiarities of innervation and to structural heterogeneity of muscle fibers.

Animals↗

PubMed2006

Endocrine control of TAG lipase in the fat body of the migratory locust, Locusta migratoria.

Aspects of the role and activation of the enzyme triacylglycerol lipase (TAG lipase) in the fat body of the migratory locust Locusta migratoria were investigated. TAG lipase is under the hormonal control of the three endogenous adipokinetic peptides of the migratory locust, Locmi-AKH-I, Locmi-AKH-II and Locmi-AKH-III. Injection of low doses (5-10 pmol) of each peptide causes an increase in lipase activity. The activation of lipase is time dependent: an elevated activity was recorded 15 min after injection of 10 pmol Locmi-AKH-I and maximum activation was reached after 45-60 min. The activation of TAG lipase is also dose-dependent. Doses of 2 pmol of each Locmi-AKH had no effect, whereas 5 pmol caused a significant activation. Maximum activation is reached with a dose of 10 pmol. Analogues of the second messengers cAMP (cpt-cAMP) and IP(3) (F-IP(3)) both activate the enzyme glycogen phosphorylase whereas only cpt-cAMP, but not F-IP(3), activates TAG lipase; cpt-cAMP elevates the lipid levels in the haemolymph. Activation of lipase is specific to the three endogenous AKH peptides: 5 pmol of the endogenous peptide Locmi-HrTH and 10 pmol of corazonin failed to activate lipase. High doses of octopamine did not activate lipase nor did they elevate the lipid concentration in the haemolymph. TAG lipase is stimulated by flight activity but activation is slower than that of glycogen phosphorylase: after 30 min of flight or after 5 min of flight plus 1h of subsequent rest, activity of TAG lipase is increased, but not immediately after 5 min of flight. In contrast, glycogen phosphorylase is activated significantly after 5 min of flight. These activation patterns of the two enzymes mirror-image the concentration of their substrates in the haemolymph: there is a significant decrease in the concentration of carbohydrates after 5 min of flight, whereas no change of the concentration of lipids can be measured after such short time of flight activity; however, a subsequent rest period of 1h is sufficient to increase the lipid concentration.

Adrenergic alpha-Agonists↗

PubMed2002

Pharmacological properties of nicotinic acetylcholine receptors in isolated Locusta migratoria neurones.

Mechanically dissociated neuronal cell bodies from the thoracic ganglia of Locusta migratoria were viable in culture conditions for up to 2 days and were voltage-clamped to record the effects of GABAergic drugs and physostigmine on the membrane conductance and ACh responses of the dissociated cells. Bicuculline, hydrastine, and gabazine inhibited the EC50 ACh responses of the cells. Both bicuculline and hydrastine were full inhibitors of the ACh responses but gabazine behaved as a partial inhibitor. Bicuculline, hydrastine, and gabazine inhibited the ACh responses in a non-competitive and voltage-independent fashion, suggesting that they are allosteric inhibitors of locust nicotinic ACh receptors. Physostigmine activated currents when applied onto isolated locust neurones. The responses activated by physostigmine were inhibited competitively by tubocurarine, which indicates that physostigmine interacts with the ACh site of locust nicotinic ACh receptors. However, maximal concentrations of physostigmine elicited currents of smaller amplitudes to those evoked by maximal ACh concentrations. Single-channel recordings suggest that the partial efficacy of physostigmine may reflect the low frequency of opening of physostigmine-induced single currents relative to that of ACh-single currents.

Acetylcholine↗

PubMed1991

Identification of a diuretic hormone of Locusta migratoria.

We have isolated a peptide from brains and corpora cardiaca of Locusta migratoria which is immunologically related to the diuretic hormone of Manduca sexta. We determined its structure as a 46 amino acid linear peptide with 43-50% identity to the M. sexta hormone. Moreover, we showed that the new peptide functions as a diuretic hormone in L. migratoria, stimulating urine production by Malpighian tubules and elevating levels of cAMP in tubules.

Amino Acid Sequence↗