Primary structure of proteins from the wing cuticle of the migratory locust, Locusta migratoria

Wing cuticle from pharate adult locusts, Locusta migratoria, contains several prominent proteins which occur as minor components or are completely absent in other cuticular regions. Six of the wing-specific proteins have been purified and their amino acid sequences determined by combined use of mass spectrometry and automated Edman degradation. During the sequence determination very long sequence runs (90-121 residues) were necessary in order to establish the primary structure. All the wing-specific cuticular proteins from locusts contain the repeated short sequence motif -Ala-Ala-Pro-Ala/Val-, which is common for all hitherto sequenced cuticular proteins from pharate locusts. Several of the wing-specific proteins also possess an N-terminal region rich in glycine, tyrosine and leucine, characteristic for many locust cuticular proteins. Two of the analysed proteins have a conserved 61-residue sequence in common with a previously sequenced protein from locust wing cuticle and with two proteins from the pharate cuticle of adult Tenebrio molitor. Possible roles for the various sequence motifs are discussed.     

Sequence of the hexameric juvenile hormone-binding protein from the hemolymph of Locusta migratoria

The cDNA for the hexameric hemolymph juvenile hormone-binding protein (JHBP) from the migratory locust has been cloned and sequenced. Antiserum raised against purified JHBP was used to identify clones in an expression library. The 4.3-kilobase JHBP mRNA codes for 668 amino acids (74.4 kDa) and contains 2 kilobases of 3'-untranslated region. The derived amino acid sequence reveals that locust JHBP represents a new group within the hexamerin family of arthropod proteins. JHBP appears to be more closely related to arthropod hemocyanins, the believed ancestors of the family, than to the other known insect hexamerins. The mRNA shows a high (89%) bias to codons ending in G or C and the codons ending in A or T are clustered and concentrated toward the 5' end, suggesting a mosaic gene structure. The recombinant bacterially expressed protein bound [3H]JH III with the same affinity as the protein from hemolymph. A truncated version of JHBP lacking 53 amino acids from the N terminus did not bind JH III. Hybridization analysis of fat body JHBP mRNA in locusts that had been treated with precocene and a JH analog did not give clear evidence for regulation by JH.     

First results of the antibacterial defense reactions of Locusta migratoria larva and imago

The echocardiographic features of mitral valvular motion in a patient with classic rheumatic mitral stenosis are presented. Two unusual features were noted, and the important of careful echocardiographic scanning of the mitral valve is imphasized. The theories for the classic echocardiographic abnormalities of mitral stenosis are briefly considered in light of the findings in this case.     

Role of phagocytosis and soluble antibacterial factors in experimental immunization of Locusta migratoria

Last instar larvae of Locusta migratoria can be protected ("vaccinated") against lethal doses of Bacillus thuringiensis by previous injections of low doses of this pathogen. If iron saccharate is injected in to larvae prior to the administration of the "vaccinating" dose of Bacillus thuringiensis, no antibacterial protection can be induced. Injection of iron saccharate in to "vaccinated" larvae does not interfere with the induced protection; such larvae resist lethal doses.     

The adipokinetic cells in the corpus cardiacum of Locusta migratoria preferentially release young secretory granules

The influence of flight activity on the release of secretory granules from the adipokinetic cells in the corpus cardiacum of Locusta migratoria was studied. Two labeling methods, an enzymatical and a radioactive one, were used to label young, newly synthesized secretory granules and so distinguish them from older, preexisting granules. Both methods demonstrated that the ratio between the numbers of labeled and unlabeled secretory granules was lower in flight-stimulated adipokinetic cells than in unstimulated cells. This ratio was lower in both the cell bodies and the cell processes of flight-stimulated cells. After flight there was no detectable change in the total number of secretory granules, which indicates that the synthesis of new secretory granules is not inhibited by flight activity. Rather, the tendency of flight-stimulated cells to have more trans-Golgi networks labeled with wheat-germ agglutinin-conjugated horseradish peroxidase suggests that the synthesis of new secretory granules was enhanced by flight. The results led to the conclusion that young secretory granules were preferentially released over older secretory granules.     

Reconfiguration of the respiratory network at the onset of locust flight

Reconfiguration of the respiratory network at the onset of locust flight. J. Neurophysiol. 80: 3137-3147, 1998. The respiratory interneurons 377, 378, 379 and 576 were identified within the suboesophageal ganglion (SOG) of the locust. Intracellular stimulation of these neurons excited the auxillary muscle 59 (M59), a muscle that is involved in the control of thoracic pumping in the locust. Like M59, these interneurons did not discharge during each respiratory cycle. However, the SOG interneurons were part of the respiratory rhythm generator because brief intracellular stimulation of these interneurons reset the respiratory rhythm and tonic stimulation increased the frequency of respiratory activity. At the onset of flight, the respiratory input into M59 and the SOG interneurons was suppressed, and these neurons discharged in phase with wing depression while abdominal pumping movements remained rhythmically active in phase with the slower respiratory rhythm (Fig. ). The suppression of the respiratory input during flight seems to be mediated by the SOG interneuron 388. This interneuron was tonically activated during flight, and intracellular current injection suppressed the respiratory rhythmic input into M59. We conclude that the respiratory rhythm generator is reconfigured at flight onset. As part of the rhythm-generating network, the interneurons in the SOG are uncoupled from the rest of the respiratory network and discharge in phase with the flight rhythm. Because these SOG interneurons have a strong influence on thoracic pumping, we propose that this neural reconfiguration leads to a behavioral reconfiguration. In the quiescent state, thoracic pumping is coupled to the abdominal pumping movements and has auxillary functions. During flight, thoracic pumping is coupled to the flight rhythm and provides the major ventilatory movements during this energy-demanding locomotor behavior.     

Fucosterol-24,28-epoxide, an intermediate in the oxidative biodegredation of fucosterol to cholesterol by the cricket (Locusta migratoria (R. and F.)

beta-Sitosterol 1 is metabolised to cholesterol 5 by phytophagous insects. It has been previously shown that fucosterol-24,28 epoxide 3 is transformed into 5 in Locusta migratoria, desmosterol 4 being an intermediate. It is now established that locusts transform [3-3H]fucosterol propionate into the corresponding labelled epoxide 3, recovered as such or as an oxazoline derivative 11.     

Cooperation of dopachrome conversion factor with phenoloxidase in the eumelanin pathway in haemolymph of Locusta migratoria (Insecta)

Dopachrome Conversion Factor (DCF) was found in the plasma of the locust Locusta migratoria. It has an apparent molecular mass of 85,000. Its K(m) was 0.2 mM at 22 degrees C and pH 7 with L-dopachrome as substrate. It had a high substrate specificity for L-dopachrome, methyl-L-dopachrome and L-dopachrome methyl ester but no activity on the corresponding D-isomers or on dopaminechrome. DCF was devoid of any phenoloxidase activity. Under action of DCF, L-dopachrome was converted into dihydroxyindole, which showed that a decarboxylation occured in the course of reaction. Locust DCF was inhibited by indole-3-propionic acid but not by indole-3- or indole-2-carboxylic acid. It was also inhibited by L-tryptophan in a competitive manner. Inhibition and substrate specificity suggest that a carboxyl group, either free or as a methyl ester, is necessary but not sufficient for enzyme recognition. When purified prophenoloxidase was activated and then added to dihydroxyindole either prepared by chemical synthesis or obtained by action of purified DCF on dopachrome, black pigments with a maximum absorption at 540 nm were generated. Therefore in the eumelanin pathway of locust plasma, phenoloxidase can catalyze the reaction that converts the product generated by DCF.     

Structure of locust adipokinetic hormone, a neurohormone that regulates lipid utilisation during flight

Adipokinetic hormone, isolated from locust corpora cardiaca, has been identified as a blocked peptide: PCA-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2. The detailed structure is based on mass spectrometric data, substantiated in part by dansyl-Edman and carboxypeptidase data on thermolytic fragments. This is the first peptide hormone from an insect neuroendocrine organ to be fully characterised.     

Identification of a secretomotor centre in the brain of Locusta migratoria, controlling the secretory activity of the adipokinetic hormone producing cells of the corpus cardiacum

After retrograde filling of axons terminating in the glandular lobe of the corpus cardiacum (CC) of Locusta migratoria with cobalt chloride, a paired group of about 15 cobalt containing cells was demonstrated in the lateral area of the protocerebrum. The axons of these cells run via the NCC II into the glandular lobe of the CC. These small neurons have the characteristics of secretory cells; they contain secretory granules of about 1000 A in diameter. The axon terminals in the glandular lobe, making synaptic contacts with the glandular cells, contain secretory granules of the same size. It is therefore concluded that the cell groups in the protocerebrum control the activity of the glandular cells which produce an adipokinetic hormone. Arborizations of fibers of the lateral secretomotor cells are present in the dorsal neuropile of the protocerebrum, ventral of the mushroom bodies and along the tracts of the NCC I within the brain. It is proposed that these arborizations are sites of synaptic input. It is discussed that the axons of these cells might receive additional synaptic input in the storage lobe of the CC. The localization of cell bodies, the axons of which enter the storage part of the CC is described. The course of the axon tracts of the various cell groups in the protocerebrum and their connections with the NCC I and NCC II are demonstrated.     

Pseudohyphal variations of yeasts exposed to specific space flight parameters

Phenotypes of Saccharomyces cerevisiae and Rhodotorula rubra exposed to specific parameters of space flight, which were measured both quantitatively and qualitatively, produced variations in pseudohyphal formation. Both the length of the parent and branch psuedohyphal filaments varied according to specific wavelengths and energy levels of UV light exposures when phenotypic isolates were compared with the parent or ground control isolate of each yeast species.     

Isolation and identification of three ecdysteroid conjugates with a C-20 hydroxy group in eggs of Locusta migratoria

Three ecdysteroids conjugates with a hydroxy group at C-20 were isolated from developing eggs of locusta migratoria and identified as 22-phosphate conjugates of 2-deoxy-20-hydroxy-ecdysone, 20-hydroxyecdysone and 20-hydroxyecdysone acetate.     

Neural factors contributing to renin release during reduction in renal perfusion pressure and blood flow in cats

1. The participation of neural mechanisms in mediating the renin release induced by reduction of renal perfusion pressure was explored in anaesthetized cats by comparing renin release from the two kidneys, one acutely denervated and the other intact. 2. Suprarenal aortic stenosis of 10 min duration reduced renal perfusion pressure to 50 mmHg and halved blood flow to both kidneys, but cause a greater release of renin from the innervated kidney than from the contralateral denervated one (increments of 72 +/- 17 and 29 +/-20 pmol/min respectively). 3. A study of the time-course of the response during aortic stenosis of 30 min duration showed early release of renin from the innervated kidney at a time (5 min) when little release occurred from the denervated one. In later samplings (15 and 30 min) the response of the innervated kidney levelled out at somewhat lower values, and that of the denervated organ progressively increased, but remained smaller than on the side with intact nerves. 4. There was no parallelism between renin release and renal vasomotor changes induced by aortic stenosis, as vasomotor changes were equal in the two kidneys and remained constant from beginning to end of stenosis. It is concluded that a significant part of the renin release induced by aortic stenosis is dependent on neural mechanisms: the neural differs from the non-neural component in being of more rapid onset and probably of shorter duration.     

Termination of imaginal diapause of female Tetrix undulate (Sow.) (Orthoptera, Tetrigidae) by implantation of the corpora allata of an active female Locusta migratoria

The effect of implanted active corpora allata on the reproductive diapause in adult females of grasshopper, Tetrix undulata (Sow.) was investigated. Implantation of one corpus allatum originating from sexually mature, adult female Locusta migratoria donors effectively terminated reproductive diapause by inducing oocyte development and egg-laying. The diapause-break is the same in females reared at 8, 12, 16 hours light at 30 degrees or 25-20 degrees. There is no difference between females reared with male or without male.     

陡脉冲发生器电路中杂散参数的分析和补偿

在陡脉冲发生器电路中,杂散参数不仅影响输出波形,还影响着系统的稳定和电路元器件的安全.为了提高输出波形的质量,抑制输出脉冲的振荡,保证元器件长期可靠的运行,需要对电路中杂散参数进行有效的分析和补偿.本文通过对脉冲的实际输出波形进行分析,建立了陡脉冲发生器电路的杂散参数模型,总结出一种分析和补偿陡脉冲发生器电路中杂散参数的方法.模型的仿真结果精确地反映了实际波形,加入补偿环节后的电路实现了输出波形的无过冲.     

Factors contributing to the reduction of stuttering during singing

This study was conducted to determine if the reduction of stuttering typically observed during singing is associated with altered vocalization or the familiarity of the melody and lyrics of the song sung by the stutterer, or both. Subjects were eight adult male stutterers. Prior to testing, each of these individuals demonstrated that he knew the melody and lyrics of a well-known song from memory. Subsequently, subjects were asked to read these lyrics aloud and then sing them. Next, subjects had to read aloud and then sing a set of unfamiliar lyrics to the conventional melody of the same song. The stutterers' reading and singing performances were audiotaped. The dependent measures of utterance duration and stuttering frequency were extracted from the tapes. Results showed that subjects' utterance durations were significantly longer during singing than reading. The main effects of singing and familiarity were both associated with significant reductions in stuttering frequency. The greatest decrement in stuttering occurred in the condition where subjects sang the familiar melody and lyrics. These findings were interpreted to mean that changes in vocalization cannot account for all of the decrease in stuttering that occurs during singing. During song, the familiarity of the melody and lyrics being produced may also affect stuttering frequency.     

A compensation method for the disturbance in the temperature field caused by subsurface thermocouples

The presence of a subsurface thermocouple hole can lead to a local disturbance of the temperature field in a sample and to a discrepancy between the thermal history measured by the thermocouple and the thermal history in an area without a thermocouple. This phenomenon also leads to errors in the surface heat flux calculated using an inverse heat conduction model, which relies on the acquired thermal history data. This article analyzes the factors that influence the temperature discrepancy caused by a subsurface thermocouple hole. A technique called the “equivalent depth” technique is proposed to compensate for the disturbance of the temperature field due to the presence of a thermocouple hole. This technique involves off-setting the location of the thermocouple position based on the radius of the thermocouple hole. A verification of this technique for the calculation of the surface heat flux using an inverse heat conduction model with measured thermal history data is presented.