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1.
1.  Physiological adaptation to hypothermia were studied in newly hatched great snipe chicks (Gallinago media) by measuring oxygen uptake (VO2), heart rate (HR), respiratory frequency (RF), and body temperature (Tb) at different ambient temperatures (Ta).
2.  Tb of 1-day-old chicks at Ta of 35°C stabilized at about 40°C. At Ta between 20 and 30°C the chicks maintained a Tb about 8°C above Ta. Hatchlings maintained a higher gradient when active than when resting. Below 20°C they were unable to maintain a stable Tb.
3.  In resting hatchlings VO2 was similar at Ta between 35 and 20°C (Tb 40–30°C), VO2 range 1.7–2.5 ml·g-1·h-1. Below 20°C, VO2 declined with time.
4.  The HR of 1-day-old chicks fell linearly with Tb during cooling. The Q10 of the HR was 1.7 at Tb 38°C and increased to 3.0 at 29°C. The RF showed a slight tendency to decrease with decreasing Tb.
5.  It is concluded that the ability to maintain normal dexterity at low Tb is an important aspect of snipe survival strategy. Maintaining a temperature gradient rather than a constant high Tb presumably saves energy. It is suggested that the mechanisms whereby VO2 is maintained at a low Tb may involve isoenzymes and adaptations of the nervous system. However, such adaptations would not seem to affect the pacemaker mechanism as evidenced by the high Q10 of the HR.
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2.
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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3.
The following findings concerning the structure of the cytochromeb 6 f complex and its component polypeptides, cytb 6, subunit IV and cytochromef subunit are discussed:
(1)  Comparison of the amino acid sequences of 13 and 16 cytochromeb 6 and subunit IV polypeptides, respectively, led to (a) reconsideration of the helix lengths and probable interface regions, (b) identification of two likely surface-seeking helices in cytb 6 and one in SU IV, and (c) documentation of a high degree of sequence invariance compared to the mitochondrial cytochrome. The extent of identity is particularly high (88% for conserved and pseudoconserved residues) in the segments of cytb 6 predicted to be extrinsic on then-side of the membrane.
(2)  The intramembrane attractive forces betweentrans-membrane helices that normally stabilize the packing of integral membrane proteins are relatively weak.
(3)  The complex isolated in dimeric form has been visualized, along with isolated monomer, by electron microscopy. The isolated dimer is much more active than the monomer, is the major form of the complex isolated and purified from chloroplasts, and is inferred to be a functional form in the membrane.
(4)  The isolated cytb 6 f complex contains one molecule of chlorophylla.
(5)  The structure of the 252 residue lumen-side domain of cytochromef isolated from turnip chloroplasts has been solved by X-ray diffraction analysis to a resolution of 2.3 Å.
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4.
1.  Direct contact between intra-epithelial nerve endings and ciliated cells was observed in frog (Rana pipiens) palate epithelium.
2.  Electrical stimulation of the palatine nerve to the explant or the explant culture induced an increase in ciliary beat frequency in explant and outgrowth cells.
3.  Atropine inhibited electrically stimulated ciliary beat frequency increase in the explant and outgrowth cells.
4.  Gap junctional intercellular communication appears to be involved in the propagation of stimulated ciliary beat frequency increase from innervated to non-innervated ciliated cells.
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5.
1.  Paramecium bursaria was stimulated by a light spot of 10–15 m diameter, and the photosensitive site was searched by recording responses in swimming behavior and in membrane potential.
2.  Local stimulation to the anterior half of the cell caused an avoiding response.
3.  Stimulation to the cells deciliated by ethanol treatment elicited a depolarization of the membrane potential.
4.  Local stimulation to the anteroventral portion elicited a depolarization, but stimulation to the dorsal side induced no change in the membrane potential.
5.  The action spectrum of depolarization elicited by local stimulation to the anteroventral surface showed two main peaks at 420 nm and 560 nm, corresponding to those of light stimulation of the whole cell.
6.  It is concluded that a photosensitive site exists on the anteroventral surface ofParamecium, in particular within the oral groove of the cell. This local photosensitivity is discussed with respect to the mating reaction.
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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.
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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.  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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9.
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   

10.
Müller  D. G.  Frenzer  K. 《Hydrobiologia》1993,(1):37-44
Culture studies with healthy and virus-infected isolates of Ectocarpus siliculosus, Feldmannia simplex and F. irregularis gave the following results:
–  Virus particles are produced in deformed reproductive organs (sporangia or gametangia) of the hosts and are released into the surrounding seawater.
–  Their infective potential is lost after several days of storage under laboratory conditions.
–  New infections occur when gametes or spores of the host get in contact with virus particles. The virus genome enters all cells of the developing new plant via mitosis.
–  Virus expression is variable, and in many cases the viability of the host is not impaired. Infected host plants may be partly fertile and pass the infection to their daughter plants.
–  Meiosis of the host can eliminate the virus genome and generate healthy progeny.
–  The genome of the Ectocarpus virus consists of dsDNA. Meiotic segregation patterns suggest an intimate association between virus genome and host chromosomes.
–  An extra-generic host range has been demonstrated for the Ectocarpus virus.
–  Field observations suggest that virus infections in ectocarpalean algae occur on all coasts of the world, and many or all Ectocarpus and Feldmannia populations are subject to contact with virus genomes.
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11.
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   

12.
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.
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13.
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.
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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.
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15.
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   

16.
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17.
1.  The effect of outward and inward water flows through the membrane on outward potassium currents of dialyzedHelix pomatia neurons was studied.
2.  An outward water flow increased the peak and sustained outward potassium currents and accelerated the kinetics of their activation. An inward water flow had quite opposite effects—it decreased the peak and sustained potassium currents and delayed the kinetics of their activation.
3.  The analysis of the effect of water flow on the conductance of potassium channels showed that an outward water flow increased both the potassium conductance at a given potential (gk) and the maximum potassium conductance (g k max ). An inward water flow again had the opposite effect—it decreased the potassium conductance at given potential and the maximum potassium conductance.
4.  Neither an outward nor an inward water flow significantly affected the fraction of open potassium channels at a given potential [n (V)].
5.  These data suggest that in dialyzed neurons the changes of outward potassium current during water flow through the membrane are due mainly to the changes in single-channel conductance and the time constant of current activation.
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18.
1.  The reactions of tympanic nerve fibers ofLocusta migratoria were recorded by glass microelectrodes in the metathoracic ganglion.
2.  The units were classified by frequency-, intensity-, and directional characteristics as well as by their response pattern. The response to speciesspecific song is compared with the response to song ofEphippiger ephippiger.
3.  The physiological properties lead to a classification into three types of low-frequency neurons (characteristic frequency 3.5–4 kHz; 4kHz; 5.5–6 kHz) and one type of high-frequency neuron (12–20 kHz). This is similar to other species (Gray, 1960, Michelsen, 1971).
4.  Intensity-coding is done by sharp rising intensity characteristics and by different absolute thresholds of the units.
5.  There is a marked directional sensitivity with some differences between LF and HF units. In the low frequency range the tympanal organ seems to react as a pressure gradient receiver; for high frequencies another mechanism is discussed.
6.  No filtering of species-specific song takes place at the level of the receptor cells.
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19.
1.  The excitatory and inhibitory influences on the gill ofAplysia Juliana, which are mediated by the branchial nerve, were studied by means of electrophysiological techniques. Excitatory and inhibitory pathways in the nerve were stimulated simultaneously or selectively.
2.  The branchial nerve was found to contain both excitatory and inhibitory pathways which did not contain synapses in the branchial ganglion. The excitatory pathways caused longitudinal shortening of the gill along the efferent branchial vessel and the inhibitory pathways were modulatory, depressing the longitudinal shortening.
3.  Branchial nerve stimulation elicited two types of excitatory junctional potential (EJP), which were not mediated by the branchial ganglion, in a muscle cell of the efferent branchial vessel. One type was attributed to the central motor neuron and the other type to a motor neuron which is probably situated in the neural plexus of the gill periphery.
4.  Four inhibitory pathways from the central nervous system to the gill were found.
5.  Inhibitory junctional potentials (IJPs) recorded from muscle cells of the efferent branchial vessel in response to branchial nerve stimulation did not have monosynaptic characteristics. It is thought that inhibitory motor neurons which were activated by the branchial nerve might exist at the neural plexus of the gill.
6.  A single EJP which has been induced by a stimulus pulse applied to the excitatory pathway of the branchial nerve may be depressed in an all-or-none manner by a stimulus pulse applied to the inhibitory pathway, if this is done within a distinct short period prior to or after the stimulus inducing the EJP. This indicates that the central motor neuron receives presynaptic inhibition at its periphery.
7.  The motor neurons of the neural plexus seem to receive inhibitory innervation. Suppression of endogenous EJPs in the efferent vessel persisted for a long period even after cessation of stimulation.
8.  A certain branchioganglionic neuron (BGN) was found to receive inhibitory postsynaptic potential (IPSP) inputs from the branchial nerve.
9.  The multimodality of both the excitatory and the inhibitory pathways in the branchial nerve may explain the compound neural modulations of gill movements.
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20.
1.  Three cyclic diterpenoids isolated from gorgonians of theEunicea genus and characterized as eupalmerin acetate (EUAC), 12,13-bisepieupalmerin (BEEP), and eunicin (EUNI) were found to be pharmacologically active on the nicotinic acetylcholine receptor (AChR).
2.  The receptor from the BC3H-1 muscle cell line was expressed inXenopus laevis oocytes and studied with a two-electrode voltage clamp apparatus.
3.  All three compounds reversibly inhibited ACh-induced currents, with IC50's from 6 to 35µM. ACh dose-response curves suggested that his inhibition was noncompetitive. The cembranoids also increased the rate of receptor desensitization.
4.  Radioligand-binding studies using AChR-rich membranes fromTorpedo electric organ indicated that all three cembranoids inhibited high-affinity [3H]phencyclidine binding, with IC50's of 0.8, 11.6, and 63.8µM for EUNI, EUAC, and BEEP, respectively. The cembranoids at a 100µM concentration did not inhibit [-125I]bungarotoxin binding to either membrane-bound or solubilized AChR.
5.  It is concluded that these compounds act as noncompetitive inhibitors of peripheral AChR.
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