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1.
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.
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2.
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.
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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.  A retention time of 150 days in the storage reservoir leads to a quite considerable reduction in copper and lead concentration (around 75% for lead and 50% for copper), while a levelling-off in the marked variations in the water flowing in is also found.
2.  Copper concentrations in the storage reservoir and the model reservoirs show a less constant picture with time then lead concentrations. This may well be caused by the absorption of copper by e.g. phytoplankton.
3.  Treatment of the water with Fe++ or AVR seems to have no effect on the removal of lead or suspended matter.
4.  Because of the small number of measurements it is difficult to quantify these results.
5.  For statements about seasonal trends, measurements must be made over a period of at least three years; they must be made at least once a week and the sampling procedure as regards place and frequency must remain unchanged.
6.  The available data indicate that in spite of the effect of mobilisation the removal of the two metals is such that sudden drastic rises of concentration in the unfiltered surface water entering the purification installation is not to be expected.
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5.
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.
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6.
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   

7.
(1)  The inactivation of various forms of nucleoside transport with reagents blocking thiol groups was studied in whole cells ofE. coli B. No positive correlation between the efficiency of active transport and the extent or rate of inactivation could be demonstrated.
(2)  The most efficient constitutive nucleoside-transporting system was found to comprise a specific thiol component characterized by low rate of inactivation with N-ethylmaleimide; the less efficient inducible transport and the facilitated diffusion of guanosine require the integrity of another thiol component which is rapidly inactivated with N-ethylmaleimide.
(3)  The constitutive nucleoside-transporting system is completely inactivated with T4 phage, while other modes of nucleoside transport are much less affected.
(4)  Inactivation of constitutive transporting system in cells exposed to N-ethylmaleimide for a limited period of time continues long after the inhibitor has been removed, indicating storage of the inhibitor in some cellular compartment. Addition of dithiothreitol stops the inactivation immediately.
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8.
Cannibalism in teleost fish   总被引：1，自引：0，他引：1  
1.  Cannibalistic behaviour in fish is reviewed here for the first time.
2.  Cannibalism has been recorded in 36 out of 410 teleost families according to the published literature, but is considered to be more widespread than this. Finding examples of cannibalism is not difficult, and it may be more interesting to look for taxa in which the behaviour does not take place.
3.  The families that have provided the most information include the Engraulididae, Esocidae, Poeciliidae, Gasterosteidae, Percidae and Cichlidae.
4.  Cannibalism has been classified into seven types, depending on life-history stage, age difference between cannibal and prey, and whether or not they are related.
5.  Although in captive populations, cannibalism tends to increase with increasing density and decreasing food availability, its role in population regulation has not been unequivocally demonstrated in any wild population, and obtaining the necessary data presents a formidable challenge to fish ecologists.
6.  Cannibalism is of some economic importance in aquaculture, but its impact can be reduced relatively easily, by frequent grading to reduce size variability.
7.  The main proximate advantage conferred by cannibalism is assumed to be nutritional. In an ultimate sense the behaviour may have evolved as a particularly effective competitive strategy.
8.  Finally, it is considered that cannibalism deserves more attention from fish biologists. Investigations, however, should recognize the different types of cannibalistic interaction, and, in particular, should explore the different implications of kin and nonkin cannibalism
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9.
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   

10.
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   

11.
The effects of temperature, over the range 10–40 °C, on properties of locust (Schistocerca gregaria) ocellar L-neurones and of their interconnections have been investigated. At cooler temperatures, a small change in temperature has a larger effect than an equivalent change at warmer temperatures. An increase in temperature leads to the following:
1.  A decrease in input resistance, which typically halves in value as temperature increases from 15 °C to 35 °C. When synaptic transmission between photoreceptor cells and L-neurones is blocked with cobalt, temperature still affects L-neurone resistance. The membrane time constant also decreases, but the resting potential is unaffected.
2.  An increase in the sizes of rebound spikes, which are produced when hyperpolarizing pulses end. Above 35 °C, the maximum size of rebound spike is smaller than that at cooler temperatures.
3.  A decrease in the latency to response to light, and an increase in the speeds of the transient responses to changes in light.
4.  A decrease in the latency of transmission at both excitatory and inhibitory synapses between L-neurones.
5.  At excitatory synapses between L-neurones, an increase in the postsynaptic current. This is compensated by a decrease in postsynaptic membrane resistance, so that there is little effect on the size of the postsynaptic potential.
6.  At inhibitory synapses between L-neurones, a decrease in the time for the postsynaptic potential to reach its peak. The time for recovery of transmission at inhibitory synapses is unaffected by temperature.
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12.
Giles  N. 《Hydrobiologia》1994,(1):387-392
This paper reviews research results on food competition between a freshwater fish community and a breeding Tufted duck population. After the experimental removal of fish from the Main Lake, the following effects were observed:
(1)  1. Invertebrate (chironomid and gastropod) food for ducklings and adult Tufted ducks increased substantially.
(2)  2. Tufted duckling brood use of the lake increased greatly and Tufted duckling survival appears to have increased.
(3)  3. Shoveler and Pochard nested successfully for the first time.
(4)  4. Submerged aquatic macrophytes grew profusely over the lake bed for the first time leading directly to large increases in use of the Lake by wintering herbivorous waterfowl.
(5)  5. When fish were re-introduced to the Main Lake sampling bay the increases in invertebrate abundance and, to a less marked extent, macrophyte abundance were reversed.
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13.
1.  Under laboratory conditions complete development of H. sparsutum is shown within a temperature range of-0.7°C to +8°C. Constant temperatures above 10°C are lethal to the population. Larval growth (L1 to L5) is strictly temperature-dependent between-0.7 and +3.5°C, but slightly temperature compensated between +3.5 and +8°C.
2.  Rate of egg production is highest at an average daily temperature of-0.7°C.
3.  The sixth larval stage (L6) can be subdivided into a wandering and feeding period of about 40 days (at 7.3°C) and a following prepupal resting stage (PPR) with a high variability in duration, even at one and the same temperature, which ends with pupation.
4.  Entrance into this resting stage seems to be independent of environmental changes and can occur at every time of the year. Termination of the PPR depends upon light stimuli received during the entire larval period.
5.  Readiness for pupation exists when the photoperiod in the PPR exceeds that during hatching of first larva. A decreasing photoperiod during PPR triggers pupation in prepupae of various age.
6.  The diapause stage seems to be a primary factor synchronizing the life cycle with seasonal changes in the environment.
  相似文献   

14.
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.
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15.
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.
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16.
Thiolutin was found to inhibit the utilization of glucose and other growth substrates in Escherichia coli. The inhibition was detected by a sharp drop of the respiration rate after addition of the antibiotic. The actual function affected was allocated to the cytoplasmic membrane of the bacterial cells by the following evidence:
–  - spheroplasts were affected like intact cells,
–  - individual reactions of either the electron transport chain or the glycolytic pathway were not inhibited,
–  - glucose consumption in the culture stopped and the cells accumulated guanosine tetraphosphate as under starvation conditions,
–  - activation of the cell's apo-glucose dehydrogenase restored respiration via bypassing the glucose phosphotransferase system.
It was concluded that the transport of certain substrates across the membrane was inhibited.  相似文献   

17.
1.  The effect of intracellularly injected cAMP on the amplitude of excitatory postsynaptic potentials was studied using identified neurons of the snailHelix pomatia.
2.  In 25% of the experiments, postsynaptic cAMP elevation caused a pronounced augmentation of the excitatory postsynaptic potential (EPSP) amplitude, lasting up to 15–30 min.
3.  The results suggest that a cAMP increase in the postsynaptic neuron may be involved in the enhancement of synaptic efficiency.
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18.
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   

19.
1.  Small passerine migrants achieve endurance flight while fasting, together with one of the highest mass-specific energy rates. Metabolic responses to flight and fasting were examined in three species of free-living migrants (Sylvia borin, Ficedula hypoleuca, Erithacus rubecula) by measuring plasma concentrations of glucose, uric acid, triglycerides, glycerol, free fatty acids (FFA), and -hydroxybutyrate (-OHB) in three main physiological situations (feeding, overnight fasting, nocturnal flight) and while changing between these situations.
2.  Overnight-fasted birds showed low triglyceride and uric acid levels. Contrary to mammals, FFA and glycerol levels were not increased in agreement with published data on birds. The transition from feeding to fasting (post-feeding) was distinguished by a temporary rise in FFA and a drop in glucose levels.
3.  Birds utilize fat during migratory flight, indicated by high levels of FFA, glycerol, and -OHB. For the first time, high triglyceride levels were found in an exercising vertebrate. The use of protein during flight was demonstrated by high uric acid levels.
4.  Birds kept inactive after flight showed a more pronounced reduction of the fat and protein utilization and post-exercise ketosis than naturally landed birds.
5.  Differences among the three species in the metabolic pattern suggest that the garden warbler shows the greatest metabolic adaption to endurance flight, having the highest levels of fat metabolites and the highest body fat reserves.
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20.
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.
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