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1.
1.  Non-visual sensory systems are likely to be important in antarctic fish since these fish inhabit an area where low light levels occur for long periods. This study was undertaken to examine the suitability of the lateral line system for prey detection.
2.  Recordings were made from afferent fibres of the anterior lateral line in the antarctic fishPagothenia borchgrevinki.
3.  A vibrating probe was used to stimulate the lateral line at a range of frequencies between 10 and 100 Hz.
4.  Most units responded best at a stimulus frequency of 40 Hz. Below the best frequency the response typically declined steeply and at higher frequencies it was usually better sustained.
5.  Crustacea identified as major components of the diet ofPagothenia borchgrevinki were individually attached to a force transducer to determine the vibrations produced by swimming movements.
6.  The Fourier amplitude spectra of swimming crustaceans exhibited prominent low frequency peaks at 3–6 Hz and higher frequency peaks in the 30–40 Hz range.
7.  It is concluded that the overlap in the frequency response characteristics of the anterior lateral line and the frequencies produced by crustacean prey clearly establishes the suitability of the lateral line for prey detection.
8.  In several instances recordings were made from fish primary afferent neurons responding to a swimming amphipod. These recordings confirm that crustacean swimming is indeed a potent natural stimulus of the lateral line system.
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2.
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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3.
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   

4.
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   

5.
We have identified a nerve carrying auditory afferents and characterized their physiological responses in the tiger beetle,Cicindela marutha.
1.  The tympana are located at the lateral margins of the first abdominal tergum. The nerve carrying the tympanal afferents is a branch of the dorsal root from the first abdominal ganglion.
2.  Both male and female auditory afferent responses are sharply tuned to 30 kHz with sensitivities of 50–55 dB SPL.
3.  The auditory afferents show little adaptation and accurately code the temporal characteristics of the stimulus with the limit of a resolution of 6–10 ms.
4.  The difference in threshold between contralateral and ipsilateral afferents for lateral stimuli is greatest at 30 kHz and is at least 10–15 dB.
5.  Ablation studies indicate that the floppy membrane in the anterolateral corner of the tympanum is crucial for transduction while the medial portion of the tympanum is less important.
6.  The tiger beetle and acridid (locust and grasshopper) ears have evolved independently from homologous peripheral structures. The neural precursor of the tympanal organs in both animals is likely the pleural chordotonal organ of the first abdominal segment.
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6.
1.  The activity of tympanal high- and low-frequency receptors in the migratory locustLocusta migratoria was recorded with glass capillary microelectrodes, and Lucifer Yellow was then injected through the microelectrode to reveal the cells' metathoracic projections.
2.  A photodetector device was used to monitor the abdominal respiratory movements, which caused clearly visible deflections of the tympanal membrane.
3.  The auditory receptors respond not only to sound stimuli but also to the respiratory movements; these phasic (Figs. 1–3) or tonic (Fig. 4) responses are especially pronounced during the inspiration and expiration movements, and less so during the constriction phases.
4.  The magnitude of the response to sound depends on the phase of the stimulus with respect to the respiratory movements. At certain phases sound elicits no response at all (Fig. 5).
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7.
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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8.
(1)  The influence of sheep grazing of moderate grazing (MG), heavy grazing (HG), inordinate grazing (IG), over grazing (OG), and extinct grazing (EG) on vegetation succession was studied in the Stipa baicalensis steppe during 1984–1986.
(2)  The relationships between the relative sum of dominance ratio (RSDR) and the degree of succession (DS) at all stages of grazing succession in the Stipa baicalensis steppe were revealed in terms of the method of mathematical analysis under five grazing intensities mentioned above.
(3)  The dynamic models of grazing succession that are based on accurate grazing intensities in relation to succession courses were constructed using RSDR5, and DS. The models may explain the rules of grazing succession in the Stipa baicalensis steppe.
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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.
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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11.
(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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12.
1.  Some units in the lateral ocellar nerves of the locust,Locusta migratoria, are influenced transsynaptically by the activity of ascending fibres in the thoracic connectives and therefore may be efferent to the afferent ocellar system.
2.  A variety of sensory inputs excite the ocellar nerve units, including illumination of the compound eyes, active and passive movement of the wings, wind stimuli to the thorax and sound.
3.  Most ocellar interneurons are influenced transsynaptically by electrical stimulation of the cervical connectives. L-neurons are depolarized and the components of their response to a rectangular light pulse are changed in amplitude. Only a few S-neurons could be examined. All of them were excited directly or indirectly.
4.  The descending ocellar interneurons (DN's) are influenced by stimulation of the contralateral connective, perhaps via efference to the ocellus or to ocellar L-cells.
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13.
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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14.
Methyl jasmonate (JA-Me) promoted leaf abscission of succulent plant, Crassula lycopodioides, and exudation from stems and leaves after leaf abscission when it was sprayed in whole plants. Major component of the exudate was identified as sucrose based on the results described below.
(1)  The reaction of the excudate was not positive in the Somogyi-Nelson method but in the phenol-sulfuric acid method.
(2)  The exudate was hydrolyzed with invertase of Candida utilis, after that showing a positive reaction in the Somogyi-Nelson method.
(3)  Only glucose and mannose were identified in the exudate after hydrolysis with trifluoroacetic acid using a gas-liquid chromatograph (GLC).
(4)  A single peak corresponding to the retention time of sucrose was observed using a high performance liquid chromatograph (HPLC).
In addition, potassium and sodium were found in the exudate as major inorganic cations. These results suggest that exudate of Crassula lycopodioides is phloem sap, and JA-Me promotes the excudation due to the inhibition of the synthesis of callose in sieve tubes of succulent plants.  相似文献   

15.
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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16.
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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17.
In 46 isolated and 4in situ preparations of perioral skin, afferent impulse patterns, leading from cutaneous mechanoreceptors and responding to orthogonal square as well as sine-wave stimuli, were investigated in selachians (Scyliorhinus canicula).
1.  Two distinct classes of specific mechanoreceptors could be differentiated: pressure- and tension-sensitive units, excited only in either the pressure or the tension phase of standard steps. Both populations yielded PD-transfer functions with predominating D-components and slow adaptation. The pressure units (majority of trigeminal skin afferents) usually revealed lower thresholds than the tension type.
2.  Receptive areas (with a considerable portion of overlapping) and local discrimination thresholds were determined. A comparison with values of the dorsolateral region showed a twofold higher sensitivity in perioral skin. Several response parameters, such as overshoot and latency, were proved to be a function of the distance between focus and stimulus, as well as of the hydromechanical pressure bias of the skin.
3.  Under biologically relevant conditions, the focal transformation characteristics and amplitude-frequency responses of 78 cutaneous afferents were measured for low-frequency vibration. Increasing skin pressure resulted in a significant amplitude and frequency shift of different synchronization thresholds.
4.  In addition to specific responses, afferent discharges of unspecific units, sensitive to touch as well as cold, were also recorded. Most of these fibres revealed spontaneous activity, which could be modulated by superimposed mechanical stimulation.
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18.
1.  The self-adapting effects of chemical backgrounds on the response of primary chemoreceptor cells to superimposed stimuli were studied using lobster (Homarus americanus) NH4 receptor cells.
2.  These receptors responded for several seconds to the onset of the backgrounds, and then returned to their initial level of spontaneous activity (usually zero). The strongest response always occurred only during the steepest concentration change; the response then decayed back to zero or to the earlier spontaneous firing level, while the background concentration was still rising, and remained silent during the entire time that the background was maintained constant (20–30 min) (Fig. 2).
3.  Exposure to constant self-adapting backgrounds eliminated the responses of NH4 receptor cells to stimuli of concentration lower than the background, and reduced the responses to all higher stimulus concentrations tested by a nearly equal amount. This resulted in a parallel shift of the stimulus-response function to the right along the abscissa (Figs. 3 and 4).
4.  Since the response threshold was completely re-set by adaptation to backgrounds, NH4 receptors seem to function mostly as detectors of relative rather than absolute stimulus intensity across their entire dynamic range: the response to a given stimulus-to-background ratio remained the same over 3 log step increases of background concentration (Fig. 6).
5.  As in other sensory modalities, a parallel shift of response functions appears to be an important property of chemoreceptor cells, allowing for this sensory system to function over a wider stimulus intensity range than the instantaneous dynamic range of individual receptor cells.
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19.
The caudal photoreceptors (CPRs) of crayfish (Procambarus clarkii) can trigger walking and abdominal movements by their response to light.
1.  In a restrained, inverted crayfish, illumination of A6 evoked a CPR discharge followed by leg movements and bursting from the abdominal tonic flexor (TF) motoneurons. Intracellular electrical stimulation of a single CPR at high frequency (80 Hz) evoked similar responses.
2.  Responses only occurred when a single CPR axon was driven at 60 Hz or more and outlasted the stimulus.
3.  CPR stimulation also excites the pattern-initiating network (Moore and Larimer 1987) in the abdomen.
4.  The axon of the CPR projects from ganglion A6 to the brain. Terminal branches occur in the subesophageal ganglion and the brain. A small descending interneuron is dye-coupled to CPR in the subesophageal ganglion.
5.  In animals with cut circumesophageal connectives, the CPRs can evoke walking and the abdominal motor pattern.
6.  The relationship of the abdominal motor pattern to walking is altered by restraint and/or inversion. In freely moving crayfish, the cyclic abdominal motor pattern is only observed with backward walking. In restrained, inverted crayfish, the motor pattern occurs with both forward or backward walking.
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20.
1.  In this commentary we discuss results obtained by a micromethod for the study of Cl– permeability across single nerve membranes from rabbit Deiters' neurons.
2.  These results showed the presence of GABAA receptors on the nerve cell membrane cytoplasmic side.
3.  We could show that these receptor complexes have a higher affinity for GABA than their extracellularly facing counterparts. Moreover, they present a phenomenon of desensitization. Another distinct property is that upon activation by GABA, they expose positive charges at their cytoplasmic mouths.
4.  We propose that these receptor complexes could functionin situ as a device for extruding Cl– anions from the nerve cell interior. This phenomenon would create an electrochemical gradient for Cl– penetration into the cell upon the action of extracellular GABA, after its presynaptic release.
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