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1.
1.  The ommatidia of the butterfly Papilio have a fused and tiered rhabdom. The distal tier of the rhabdom is made up of four distal photoreceptors (R1–4), whereas the proximal tier is made up of four proximal (R5–8) and one basal photoreceptor cell (R9).
2.  We first confirmed by light microscopy that the ommatidia of Papilio are not twisted, i.e. have the same spatial organization all about the longitudinal axis. The polarization method, previously applied to the distal tier, hence is applicable to identify the photoreceptor location from the peak angle of the polarization sensitivity.
3.  We determined the polarization and spectral sensitivity of in total 109 proximal and basal photoreceptors in the lateral looking eye region. All of the photoreceptors were either green or red type, most of which fall into three classes as judged by the peak angles of the polarization sensitivity: around 40°, 150°, and 180° (= 0°) with respect to the dorso-ventral axis. The first two classes are formed by the proximal photoreceptors with straight microvilli oriented at the average angle of 39° (R6, 8) and 144° (R5, 7) respectively, and the third is formed by the basal photoreceptors R9 with straight microvilli oriented at 180° (= 0°). The mean polarization sensitivity (PS = maximal sensitivity/minimal sensitivity) was about 2.
4.  75% of the proximal and 48% of the basal photoreceptors were of the red type.
5.  A single ommatidium of Papilio appears to contain two to four types of spectral receptors.
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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.
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   

4.
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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5.
1.  In the compound eye of the maleChrysomyia megacephala the facets in the ventral part of the eye are only ca. 20 m in diameter, but increase abruptly to ca. 80 m above the equator of the eye. Correspondingly there is a large and abrupt increase in the rhabdomere diameter from 2 to as much as 5 urn. The far-field radiation pattern of the eye shows that, despite the large change in ommatidial dimensions, the resolution of the eye remains approximately constant across the equator: angular sensitivity of the photoreceptors and sampling raster are similar ventrally and dorsally. The main result of the large dorsal facets is a more than tenfold increase in light capture. Thus this eye provides a clear example of an insect where large dorsal facets have evolved not for higher acuity, but rather for higher light capture.
2.  Sensitivity is increased even more by a seventh photoreceptor cell joining neural superposition, as reported before for the dorsal eye of male houseflies. All seven photoreceptors have the same spectral sensitivity.
3.  Angular sensitivities in the dorsal eye are more Gaussian-shaped than the flat-topped profile expected for large rhabdomere diameters. This is explained by the anatomical finding that the dorsal rhabdomeres taper strongly. It is suggested that the combination of high photon capture and rounded angular sensitivities is advantageous for monitoring movement and position of small objects.
4.  Finally some of the constraints involved in constructing specialized dorsal eye regions for detection of small objects are considered.
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6.
Spectral sensitivity functions of a passeriform bird, the Red-billed Leiothrix Leiothrix lutea (Timalidae) were determined in a behavioural test under different background illuminations.
1.  With photopic illumination the spectral sensitivity of Leiothrix lutea covered the measured range from 320 nm to 680 nm. Four peaks of spectral sensitivity were found: a UV (370 nm), a blue (460 nm), a green (530 nm) and a red (620 nm) sensitivity peak. The spectral sensitivity was highest in the UV and decreased (over the blue and the green peak) towards the red sensitivity peak. The 4 peaks of spectral sensitivity point to 4 underlying cone mechanisms under photopic illumination and thus to a probably tetrachromatic colour vision of Leiothrix lutea.
2.  With mesopic illumination the bird's spectral sensitivity covered the measured range from 320 nm to 680 nm. Neural interactions between cone and rod sensitivities are likely to determine this function. The increased overall sensitivity and a dominant sensitivity peak at 500 nm point to a typical rhodopsin as the likely rod photopigment.
3.  Different aspects of the biological significance of the high UV sensitivity are discussed.
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7.
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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8.
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9.
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.
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10.
1.  Up to 9 kHz, the tympanal membrane of the grasshopper Chorthippus biguttulus responds with equal sensitivity at the attachment sites of the low and the high-frequency receptors; at the latter site it is also particularly sensitive between 10 and 20 kHz.
2.  The frequency spectra of the songs of both sexes exhibit maxima at 7–8 kHz, to which the membrane is well matched. In the high-frequency region, where the male songs have a peak at 30 kHz, there is no corresponding maximum in the membrane oscillation.
3.  Because the tympanal membrane is immediately adjacent to air sacs in the tracheal system, it is deflected inward and outward by as much as 80 m during the respiratory cycle.
4.  Measurements by laser vibrometry show that acoustically induced membrane oscillations are attenuated severely due to the respiratory displacement of the membrane for frequencies up to 10–12 kHz. By contrast, at higher frequencies the membrane sensitivity is doubled or tripled.
5.  As a result of these membrane effects, the discharge in the tympanal nerve was profoundly reduced in the low-frequency range, whereas above 11 kHz there was a marked increase. This modulation of auditory sensitivity affects the animals' ability to detect conspecific songs.
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11.
With the aim of clarifying the role of screening pigments in photoreceptor optics of the compound eye, a comparative study of the optical properties of the honeybee eye in the visible region of the spectrum was carried out using wild-type bees and eye colour mutantssnow, snow laranja, ivoryumberandchartreuse with total or partial blockage of the tryptophane-ommochrome pathway.
1.  The electroretinogram (ERG) of mutant eyes displayed a sharp on-peak, this component being absent from normal heterozygote eyes (Fig. 6).
2.  The ERG of newly emerged bees (a) lacked the above on-peak and showed oscillations in mutants, and (b) lacked the off-peak which always occurs in the ERG of adults in all the genotypes studied when stimulated by visible light.
3.  The resting potentials of the receptor and cone cells were not found to be affected by mutations la, and the receptor potential ins/s ands la/slaphotoreceptors appeared to be similar to that in +/+
4.  Analysis of the amplitude characteristics of the whole eye of eight genotypes showed that the relative numbers of photons absorbed from an extended light source (4.5°×16.5°) and needed to elicit a standard ERG amplitude of 1 mV were as follows:s/si u/iusla/slach1/ch1(+/+; s/+ iu/+; sla/+)=14.38.612.2(100–250). These ratios are believed to reflect the progress in ommochrome formation in these strains.
5.  Spectral sensitivity curves (SSC) were obtained using an automatic spectrosensitometer and a spectral scan method which gave accurate results. The SSC of the whole eye in+/+ peaked at a max of 543±7 nm (SD,n=6), whereas max ins/s ands la/slashifted to 528±6 nm (n=9) and 548 ±3nm (n=6) respectively. The SSC ins/+ was the same as that in+/+. The bandwidth (width at 50% of peak sensitivity) of the SSC proved to be similar in+/+ ands/+ (126±10 nm and 128±8 nm), although ins/s the SSC appeared to be significantly narrower (106±7 nm;P<0.01; fig.=" 8,=" table=" 2).=">
6.  The peak spectral sensitivity of long-wave (LW) receptors lay at 541±5 nm (SD,n=14) in+/+ and at 526±5 nm (n=13) ins/s; the spectral distributions of the peaks in these genotypes were different. The bandwidth of the SSCs of the photoreceptors were 109±11 nm in+/+ and 103±4 nm ins/s, the difference being insignificant (Fig. 8, Table 2). The SSCs ins/s fit the absorption spectrum of pigment 526 (P 526) rather well whereas those in+/+ are noticeably distorted. The same is true for the whole-eye data.
7.  A theory is advanced to account for the acceptance functions of the photoreceptors of eyes with imperfect pigmentation. Light scattering in imperfectly screened eyes was estimated using a factor which the termed we parasitic absorption coefficientp (see Theory).
8.  The acceptance functions of LW photoreceptors were measured by three methods, and the results were similar to those predicted from the theory. On this basis the coefficientp was estimated; fors/s photoreceptors it lay between 0.65 and 0.76 according to experiments with a point light source (method 1), and was as great as 2.5 according to measurements with an extended light source (method 2). The latter technique, an integral method, made it possible to detect light scattering in normal bee eye, the coefficientp reaching 0.02 (Fig. 1, Table 3).
9.  In genotypes+/+ ands la/slathe absorption spectra of screening pigments were recorded by microspectrophotometry (MSP), and greater transmission of red light than blue-green was found (Fig. 11).
10.  Taking into account the screening effect of ommochromes, it is suggested that the visual pigment of LW photoreceptors in the honeybee eye is P 526; the absorption spectrum of this is highly similar to the SSC of LW photoreceptors in thes/s eye.
11.  On the basis of our theory and experimental results, the contrast transfer function (CTF) for the white honeybee eye was estimated to be only 0.1 (for white and black patterns with the spatial wavelength sp, the acceptance angle). Thus, the absence of screening pigments from the compound eye ofsnow mutants causes the great decrease in image contrast, and this serious sensory defect may be responsible for the fact that these mutants fail to find their way home.
Dedicated to Professor H. Autrum on the occasion of his 80th birthday  相似文献   

12.
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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13.
1.  The larva of the tiger beetle (Cicindela chinensis) possesses six stemmata on either side of the head. Optical and physiological properties of two pairs of large stemmata and a pair of anterior medium sized stemmata, and responses of second-order visual interneurons (medulla neurons) have been examined.
2.  Objects at infinite distance were estimated to focus 50 m deep in the retina in the large stemmata. Receptive fields of four large stemmata, the acceptance angle of each being 90°, largely overlapped one another.
3.  The stemmata possessed a single type of retinular cell with a maximal spectral sensitivity at 525 nm, and a flicker fusion frequency of 25–50 Hz.
4.  Medulla neurons expanded fan-shaped dendrites in the medulla neuropil, and their axons extended into the protocerebrum. They responded to illumination with a variety of discharge patterns. They also responded with spike discharges to moving objects and to apparent movements provided by sequential illumination or extinction of LEDs. They did not show directional selectivity. They possessed well-defined receptive fields ranging from 30° to 105°.
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14.
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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15.
1.  Monopolar cells of the first visual ganglion, the lamina, of the bee were recorded from and stained intracellularly.
2.  Several different response types to pulses of spectral light were found. The most common response type hyperpolarized in a phasic-tonic fashion. The tonic hyperpolarizing response frequently decreased gradually, but in some cases increased with lasting illumination. Some cells also gave a transient response to light-OFF. In contrast, one stained and several unstained cells showed depolarizing responses. Five cells exhibited spiking responses under normal physiological conditions.
3.  The V/log I-functions were steeper than those of the photoreceptors and, in some cases, had both rising and falling parts with increasing intensities. The spectral sensitivity obtained with the constant response method showed a peak in the green (510–535 nm) in most cells. A series of spectral flashes revealed an additional type with highest sensitivity in UV. Indirect evidence was found in one cell for spectral opponent processing.
4.  Two morphological types of monopolar cells were stained. These correspond well to Ribi's (1976) L1 and L2 cells, with some differences in detail. The most frequently stained cell type closely resembles his L2 type. All 3 stained spiking cells were of this type.
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16.
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   

17.
1.  The noninvasive techniques of intracellular optical physiology were used to measure reflectance changes in the deep pseudopupils of various regions of the apposition compound eyes of 3 species of stomatopod crustaceans.
2.  Upon exposure to light, prominent changes in reflectance were observed in all eye regions of all species studied. Generally, the response was an increasing reflectance following stimulus onset; however, in the lateral rows of the central ommatidial band of gonodactyloid stomatopods, the response was a rapid decrease in reflectance. Halftimes for the normal, increasing response were about 5 s in the gonodactyloid species and an order of magnitude longer in the squilloid species.
3.  The reflectance changes were probably produced by pupillary mechanisms similar to those previously described for insects. Evidence for this included the form and speed of the response, the observation that fluorescence from the visual pigment diminished with a similar time course to the increase in reflectance, and the tendency of the response to sensitize to repeated stimulation.
4.  Two spectral classes of photoreceptor were distinguishable in both the peripheral and central band regions of the eye. These classes were most sensitive to ultraviolet (360 nm) or long-wavelength (500 nm) light. The classes were distinguishable by the form and speed of the reflectance changes they produced when stimulated. Results of univariance experiments suggested that only these 2 classes existed in each eye region examined.
5.  In all species and ocular regions examined, the reflectance-change response operated over an intensity range of 3–4 orders of magnitude.
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18.
1.  In a concentration-dependent manner neuropeptide Y was found to be a potent inhibitor of the spontaneous activation of human granulocytes and macrophages as well asMytilus edulis immunocytes.
2.  Neuropeptide Y also inhibited the chemotaxic response of these immunocytes to the chemoattractant f-MLP.
3.  Incubation of both the human and the invertebrate immunocytes in f-MLP (10–9 M) causes activation as noted by random locomotion (chemokinesis). Neuropeptide Y also blocked f-MLP-induced chemokinesis.
4.  The results suggest that neuropeptide Y may, in addition to other functions, serve as an endogenous regulator of immunocyte function.
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19.
1.  Spectral-sensitivity functions of large-field movement-detecting units in the lobula plate of the dronefly Eristalis tenax L., which is a Batesian mimic of the honeybee, were measured using visual stimuli consisting of light flashes, or moving gratings. Two classes of units were studied, one class responding to inward horizontal motion in the contralateral eye (presumably the homologue of the well-known HI in other fly species), and the other class responding to vertically-down-ward motion in the contralateral eye.
2.  In both classes of units, the spectral-sensitivity function of the response to flashes is characterized by two peaks, one in the UV at ca. 350 nm and the other in the blue at ca. 475 nm (Figs. 3, 8). It resembles the spectral-sensitivity function of the R1-R6 class of receptors in other flies.
3.  In both classes of units, the spectral-sensitivity function of the response to movement is characterized by a single peak, occurring in the blue at ca. 450 nm (Figs. 7, 9).
4.  Control experiments on homologous units in the Australian Sheep Blowfly Lucilia cuprina, using identical stimulating conditions reveal that the response to flashes as well as movement possesses a dual-peaked spectral sensitivity, with one peak in the UV and the other in the blue-green region of the spectrum (Figs. 10–12).
5.  The results indicate that the pathways subserving the inputs to movement-detecting neurons in Eristalis are driven by more than one spectral class of photoreceptors. They also reveal that the spectral sensitivity of movement detection in Eristalis bears a closer resemblance to that of the honeybee, than to that of other flies. This similarity to the honeybee may arise from the fact that the dronefly and the honeybee occupy similar ecological niches, both foraging for nectar in flowers.
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20.
1.  We examined the retinas of 2 species of stomatopods in the superfamily Squilloidea, Cloridopsis dubia and Squilla empusa, and 2 species of the super-family Lysiosquilloidea, Coronis scolopendra and Lysiosquilla sulcata, using microspectrophotometry in the visible region of the spectrum.
2.  Retinas of all species included numerous photostable pigments, such as green reflecting pigment, hemocyanin, colored oil droplets, and vesicles. Both lysiosquilloid species also had intrarhabdomal filters within specialized photoreceptors of the midband.
3.  Squilloid species contained a single visual pigment throughout all photoreceptors, with peak absorption at medium wavelengths (near 515nm). Retinas of lysiosquilloids contained a diversity of visual pigments, with estimated max values ranging from 397 to 551 nm.
4.  Spectral sensitivity functions were estimated for the lysiosquilloid species based on estimates of visual pigment nax, photoreceptor dimensions, and specific absorbances of the visual pigments and intrarhabdomal filters. Ommatidia of midband Rows 1 to 4 contained pairs of narrowly tuned spectral receptors, appropriate for spectral discrimination, while ommatidia of midband Rows 5 and 6, and all peripheral ommatidia, had broad spectral sensitivity functions.
5.  Lysiosquilloid stomatopods have retinas that closely resemble those of gonodactyloids both structurally and in their visual pigment diversity. In contrast, squilloids have retinas that are much simpler. These differences appear to be related to the habitats and activity cycles of species belonging to the 3 major superfamilies of stomatopod crustaceans.
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