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1.
Flight metabolism of locusts has been extensively studied, but biochemical and physiological methods have led to conflicting results. For this reason the non-invasive and non-destructive method of 31P NMR spectroscopy was used to study migratory locusts, Locusta migratoria, at rest and during flight.
1.  In the flight muscle of resting locusts the ratio of phosphoarginine to ATP was the same whether determined by NMR (1.76) or biochemically, but the NMR-visible content of inorganic phosphate (Pi) was only 40% of ATP, i.e., much lower than total Pi as determined biochemically. This suggests that most of the Pi in flight muscle is not free, and hence not available as substrate or effector for cytosolic enzymes. Similarly, the free content of ADP and AMP in resting muscle was calculated to be much lower than the total content.
2.  Flight brought about a marked increase in Pi and a decrease in phosphoarginine in flight muscle although there was no change in intracellular pH.
3.  At the initiation of flight a new steady state of ATP, Pi, and phosphoarginine was rapidly established and minimal changes occurred after the first 2 s of flight.
4.  From the free contents of ATP and phosphoarginine in working flight muscle the flight-induced fractional increases in free ADP and free AMP were calculated to be 5.0-fold and 27.4-fold, respectively. As Pi, ADP, and AMP are substrates and potent effectors of enzymes, the flight-induced increase in their contents is likely to have marked effects on metabolic flux in working muscle.
5.  After short-term flight as well as prolonged flight, phosphoarginine, ATP, and Pi returned rapidly to their preflight levels, indicating that metabolic recovery from flight is rapid.
6.  The locust appears to be an appropriate model for the study of metabolic regulation in aerobic muscle during exercise.
Dedicated to Professor Dr. Ernst Zebe (University of Münster) on occasion of his 65th birthday.  相似文献   

2.
J. Robb 《Human Evolution》1994,9(3):215-229
In recent years anthropologists have made much progress in understanding ancient activities from skeletal remains. In this paper, material from the Iron Age cemetery at Pontecagnano (VII-IV century BC) is used to illustrate activity-related traits of eight basic categories:
(1)  idiosyncratic patterns of dental wear
(2)  activity-related articular degeneration
(3)  non-pathological functional alterations (neoformations, contact facets)
(4)  mechanical remodelling of bone architecture
(5)  enthesopathies (muscular lesions)
(6)  traumatic lesions
(7)  activity-related pathologies
(8)  activity-related nutritional characteristics
These traits, and others, can be used not only singly but in conjunction to define (a) patterns of activity and occupational specialization for individuals, and (b) distributions within society reflecting the basic division of labor by geneder and class.  相似文献   

3.
Twelve of the main European LCA software packages currently available are examined wirh the aim of establishing which are the most appropriate for LCAs on industrial processes. The packages performances are assessed in terms of
–  • Volume of Data
–  • WindowsTM environment
–  • Network Capabilities
–  • Impact Assessment
–  • Graphical representation of the inventory results
–  • Sensitivity analysis
–  • Units
–  • Cost
–  • User Support
–  • Flow Diagrams
–  • Burdens allocation
–  • Transparency of data
–  • Input & output parameters
–  • Demo version
–  • Quality of data
The review concludes with a Specification Table which summarises the facilities available on each software package. The general conclusion from this study is that for industrially based LCAs, there are four packages which may offer advantages over the rest. These are The Boustead Model, The Ecobilan Group’s TEAM™, PEMS 3.0 and SimaPro 3.1.  相似文献   

4.
1.  Coupling mechanisms between ciliary beating and the membrane potential in Paramecium were investigated under voltage clamp applying intracellular pressure injection of cAMP, cGMP and Ca-EGTA buffer. Ciliary responses following step changes in membrane potential were recorded by high-speed video on magnetic tape.
2.  Injections of cAMP and cGMP up to millimolar concentrations caused no detectable changes in the frequency voltage relationship. A minor effect was that the ciliary reorientation towards the anterior cell end (reversal) tended to be inhibited with depolarization up to 10 mV.
3.  Injection of Ca2+ into the cell clamped at the resting potential caused a transient anteriad ciliary reorientation and a simultaneous increase in the beating frequency.
4.  Injection of EGTA (to buffer Ca2+ below 10–8 M) was ineffective in relation to frequency for several minutes. After this time, hyperpolarization- and depolarization activated frequency responses of EGTA-injected cells were increasingly inhibited. The ciliary reorientation following depolarization was not affected by EGTA.
5.  A posterior contraction of the cell diameter was noticed upon membrane hyperpolarization. The contraction coincided in time with the increase in beating frequency.
6.  The results support the view that the voltage-dependent augmentation of the ciliary beating rate is not directly mediated by an intracellular increase in either cAMP or cGMP.
7.  The role of Ca2+ as intracellular messenger in the ciliary and somatic compartments is discussed.
  相似文献   

5.
1.  We have obtained a cDNA clone encoding a human retinal D2 dopamine receptor.
2.  The longest open reading frame (1242 bp) of this clone encodes a protein of 414 amino acids having a predicted molecular weight of 47,000 and a transmembrane topology similar to that of other G protein-coupled receptors.
3.  Transient transfection of COS-7 cells with an expression vector containing the clone resulted in expression of a protein possessing a pharmacological profile similar to that of the D2 dopamine receptor found in striatum and retina.
4.  Northern blot analysis indicated that, in rat brain and retina, the mRNA for this receptor was 2.9 kb in size.
5.  In situ hybridization was performed to examine the distribution of the mRNA for this receptor in human retina. Specific hybridization was detected in both the inner and the outer nuclear layers.
6.  These findings are consistent with prior physiological and autoradiographic studies describing the localization of D2 dopamine receptors in vertebrate retinas. Our observations suggest that photoreceptors as well as cells in the inner nuclear layer of human retinas may express the mRNA for this D2 dopamine receptor.
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6.
1.  Seasonal changes in the half-times (0.5) for calcium influx and outflux in bone, skin and scales, and soft-tissue compartments ofF. kansae were measured.
2.  The size of diffusible calcium pools in the three compartments was estimated from the ratio of the loading and unloading half-times. Both the bone and skin and scales compartments contain diffusible calcium pools which increase in size during the summer months.
3.  The calcium in the soft-tissue compartment is all diffusible, and the kinetics indicate that this compartment receives calcium from the other two compartments.
4.  Hypophysectomy reduced the rate of calcium turnover in summer animals to the levels measured in intact winter animals. Such treatment also affected the distribution of radiocalcium within the animal.
5.  It is concluded that acellular bone is a metabolically active tissue.
  相似文献   

7.
Conclusions  
(1)  The aminoesters inhibit glucose-stimulated proton extrusion by yeast cells.
(2)  The inhibitory activity depends on aliphatic carbon chain length.
(3)  The inhibition of proton extrusion is concentration-dependent.
(4)  The aminoesters stimulate quinacrine accumulation in vacuoles of yeast cells so they should possess affinities for lysosomes.
This work was supported byKBN grant no. 7 A203 013 07.  相似文献   

8.
1.  At 28°C conversion efficiency of total nitrogen (TN) was inversely related to size.
2.  In the pre-adult stage protein nitrogen (PN) conversion efficiency was high whereas in the Post-adult stage non-protein nitrogen (NPN) conversion efficiency was high.
3.  Lower temperature (20°C) was not congenial for PN conversion.
4.  Higher temperature favoured PN conversion for smaller fish but NPN for larger fish.
  相似文献   

9.
1.  At ambient temperatures (T a) between 39 and 43°C, specimens of the waterproof treefrogChiromantis xerampelina, resting quietly in wind tunnels, adjust rates of evaporative water loss (EWL), maintaining body temperature (T b) 2–4°C belowT a.
2.  Brain heating and cooling, respectively, increased and decreased steady-state rates of thermoregulatory evaporative water loss (EWL), driving negative feedback changes inT b.
3.  Continuous infusions of epinephrine resulted in specific, dose-dependent, saturable increases in EWL; isoproterenol was more potent than epinephrine, which was more potent than phenylephrine. Tyramine injection also stimulated EWL.
4.  Non-specific increases in EWL stimulated by injections of cholinergic agonists were weakly antagonized by atropine, but thermally induced EWL, as well as adrenergically and cholinergically stimulated increases in EWL, were abolished by beta-adrenergic antagonists.
5.  Sweating decreased andT b increased during ganglionic blockade.
6.  The observations suggest thatC. xerampelina controls thermoregulatory EWL by modulating the sympathetic nervous outflow stimulating beta-adrenergic receptors on cutaneous mucous glands.
  相似文献   

10.
1.  Rates of oxygen consumption were measured during locomotion in five species of marsupials of the family Dasyuridae. The body weights of the animals ranged between 0.15 and 1.12 kilograms.
2.  The rate of change of power input with speed was generally lower than equivalent eutherian values. The extrapolation to zero speed was consistently a higher multiple of resting metabolic levels than found in eutherians.
3.  The minimum cost of locomotion (M run) as a function of body mass (wt) is described by the equationM run=4.75 wt–0.34. The exponent is similar to that described for eutherians and reptiles, but the constant term is significantly lower.
4.  Metabolic scope in these animals is similar over the size range used and may be greater than in eutherians.
5.  Heat dissipation during locomotion has been partitioned into evaporative and non-evaporative routes. Storage of heat during locomotion was never more than fifty per cent of total production.
  相似文献   

11.
1.  The cochlea of the horseshoe bat,Rhinolophus ferrumequinum, was frequency mapped by exposing for 30 min to one or two continuous pure tones of intensities between 70 and 110 dB SPL. The evaluation was made by differentiating between normal and swollen nuclei of the outer hair cells (OHC) of the organ of Corti and by measuring the diameter of the nuclei of the OHC.
2.  In control animals the radial diameter of the OHC nuclei varies systematically from a mean of 2.85 m at the base to 3.2 um at the apex (Fig. 1).
3.  All frequencies used for exposure were normalized to the resting frequency (FR), which is the frequency of the pure tone component of the orientation sound in a non-flying bat. The individual FR lay between 82.6 and 83.3 kHz.
4.  For analysing the small frequencies between 83.0 to 86.0 kHz in which relevant echoes occur, 3.15 mm length of the basilar membrane is used, about the same length as for the octaves from FR/4 to FR/2 (2.85 mm) and from FR/2 to FR (3.2 mm) (Fig. Ca, b).
5.  The discontinuity of the mechanical data at 4.5 mm of the length of the basilar membrane (part I of this paper) coincides with FR and the less pronounced discontinuity at 7.8 mm coincides with FR/2.
6.  Location and mechanism of the auditory filter are discussed.
  相似文献   

12.
Oncostatin M, a multifunctional cytokine   总被引：6，自引：0，他引：6  
  相似文献   

13.
In the rift valley (North-East of France/South-West of Germany), the Rhine runs freely for 300 km from South to North. The absence of natural obstacles allows the development of a very regular profile of the river. We have therefore an opportunity to study very gradual modifications of the alluvial forest communities of the fluvial corridor from upstream to downstream, according to the gradual evolution of the ecological factors, related to slope decrease and hydrological modifications.We describe, from Basel to Mainz:
1)  modification of dynamic processes in the forest communities such as successional sequences or sylvigenetic mosaïcs of the terminal stages.
2)  modification of species richness.
3)  reduction of species diversity.
4)  simplification of the forest stratification.
5)  modification of efficiency of the biogeochemical cycling.
6)  ecological vicariances.
7)  modification in species behaviour.
  相似文献   

14.
1.  Properties of the membrane currents ofDidinium nasutum have been investigated under voltage clamp in different solutions and after deciliation.
2.  Theearly transient Ca2+ inward current activates in a voltage-dependent manner. Inactivation is both Ca2+ -dependent and voltage-dependent.
3.  Alate Ca2+ current rises with time to peak > 50 ms and decays in the order of seconds.
4.  Activation and inactivation of the late Ca2+ current is voltage-dependent.
5.  The delayed outward current is activated by voltage. The kinetics of this K+ current, but not its amplitude, are enhanced in the presence of intracellular EGTA.
6.  The two voltage-dependent Ca2+ channels are located in the cilia, whereas all K+ channels are restricted to the somatic membrane.
  相似文献   

15.
3DFS is a 3D flexible searching system for lead discovery. Version 1.0 of 3DFS was published recently (Wang, T.; Zhou, J. J. Chem. Inf. Comput. Sci., 1998, 38, 71–77). Here version 1.2 represents a substantial improvement over version 1.0. There are six major changes in version 1.2 compared to version 1.0.
1.  A new rule of aromatic ring recognition.
2.  The inclusion of multiple-type atoms and chains in queries.
3.  The inclusion of more spatial constraints, especially the directions of lone pairs.
4.  The improvement of the query file format.
5.  The addition of genetic search for flexible search.
6.  An output option for generating MOLfiles of hits.
Besides the above, this paper supplies:
1.  More query examples.
2.  A comparison between genetic search and Powell optimization.
3.  More detailed comparison between 3DFS and Chem-X.
4.  A preliminary application of 3DFS to K+ channel opener studies.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1007/s0089490050231  相似文献   

16.
Artificial magnetic fields (MF) influence physiological processes in bees.
1.  An inhomogeneous, static magnetic field (IMF) reduces the flying activity of bees and increases their life span by more than 60%.
2.  The content of the ageing pigment lipofuscin in brain and, to a lesser extent, in thorax muscles increases with the physiological age. The content of lipofuscin of the thorax muscle is only 1/5 that of the brain.
3.  Despite their increased chronological age (60–74%) brain lipofuscin of bees under conditions of an inhomogeneous, static magnetic field is slightly reduced compared with bees in natural earth's magnetic field (EMF) conditions. No effects could be registered in the muscle lipofuscin of the thorax.
4.  There was no correlation between the content of lipofuscin and the chronological age.
5.  Flying activity is also reduced by horizontal magnetic fields (0.40–1.45 Oe).
6.  Dance tempo is reduced in compensated EMF and amplified static magnetic fields (0.84 Oe). Dance tempo is drastically reduced if compensation of the EMF is followed by application of a 5 Hz magnetic field with 1.04 Oepp, directed E-W.
Dedicated to Prof. Dr. Drs. h.c. M. Lindauer on the occasion of his 70th birthday  相似文献   

17.
1.  Authentic human acetylcholinesterase (AChE) was expressed inEscherichia coli under regulation of the constitutivedeo promoter or the thermoinduciblePL promoter.
2.  To facilitate expression in the prokaryotic system, recombinant human AChE (rhAChE) cDNA was modified at the N terminus by oligonucleotide substitutions in order to replace some of the GC-rich regions by AT. These modifications did not alter the amino acid sequence but resulted in ample production of the protein.
3.  rhAChE accumulated in the cells and reached a level of 10% of total bacterial proteins. A partially purified inactive recombinant protein was recovered from inclusion bodies.
4.  Active rhAChE was obtained after solubilization, folding, and oxidation, although the recovery of the active enzyme was low. A 20- to 40-fold increase in enzymatically active rhAChE was achieved by replacing Cys580 by serine.
5.  The recombinant enzyme analogue was indistinguishable from native AChE isolated from erythrocytes in terms of substrate specificity and inhibitor selectivity.
  相似文献   

18.
1.  We used laser vibrometry and free field sound stimulation to study the frequency responses of the eardrum and the lateral body wall of awake male Eleutherodactylus coqui.
2.  The eardrum snowed one of two distinct frequency responses depending on whether the glottis was open (GO response) or closed (GC response) during the measurement.
3.  The lateral body wall vibrated with a maximum amplitude close to that of the eardrum and in the same frequency range.
4.  Covering the frog's body wall with vaseline reduced the vibration amplitude of the GC response by up to 15 dB.
5.  When a closed sound delivery system was used to stimulate a local area of the body wall the eardrum also showed one of two types of responses.
6.  These results suggest that sound is transmitted via the lung cavity to the internal surface of the eardrum. This lung input has a significant influence on the vibrations of the eardrum even when the glottis is closed.
7.  The vibration amplitude of the eardrum changed with the angle of sound incidence. The directionality was most pronounced in a narrow frequency range between the two main frequencies of the conspecific advertisement call.
  相似文献   

19.
1.  The overall rate of feeding at 28°C bears an inverse relationship to size; the time course of feeding appears to be size-independent and shows a decline with increase in time.
2.  Absorption efficiency is independent of size.
3.  The rates of absorption and conversion and conversion efficiency are inversely related to size.
4.  The rate of feeding is reflected on the rates of absorption and conversion.
  相似文献   

20.
Metabolic characteristics of experimental hepatoma cells include elevated rates of glycolysis and lipid synthesis. However, pyruvate derived from glucose is not redily oxidized, and the source of acetly CoA for lipid synthesis in As-39D cells has not been characterized. In this study ketone bodies were examined as a possible source of acetyl CoA in AS-30D hepatoma cells.The major findings were:
1.  Acetoacetate was utilized by AS-30D cells, with14C-lipid and14CO2 as major products of [3-14C] acetoacetate.
2.  Lipid synthesis from acetoacetate was dependent on the presence of glucose in the medium.
3.  Acetoacetate supported rapid respiration by AS-30D mitochondria in the presence of 0.1 mM malate.
4.  Succinly CoA acetoacetyl CoA transferase activity in AS-30D mitochondria was approximately 40 fold greater than that found in rat liver mitochondria.
5.  Addition of acetoacetate, but not -hydroxybutyrate decreased conversion of [1-14C] acetate to14CO2, presumably by diluting the specific radioactivity of the acetyl CoA derived from the acetate tracer.
6.  In the presence of glucose, approximately one fourth of acetoacetate utilized was converted to lipid. This result is consistent with elevated lipogenesis postulated by the truncated TCA cycle hypothesis. These data demonstrate for the first time the flux of acetoacetate carbon to lipid and CO2 in hepatoma cells and suggest that increases in the ambient concentration of acetoacetate, occurring in fasting or malignant cachexia, could produce increases in the utilization of this ketone body by hepatoma cells containing 3-oxyacid CoA transferase activity.
  相似文献   

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