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1.
To examine the influence of the spectral characteristics of underwater light on spectral sensitivity of the ON and OFF visual pathways, compound action potential recordings were made from retinal ganglion cells of threespine stickleback from different photic regimes. In fish from a red-shifted photic regime (P50 680 nm for downwelling light at 1m), peak sensitivity of both the ON and OFF pathways was limited to long wavelength light (max 600–620). In contrast, the ON pathway of fish from a comparatively blue-shifted (P50 566 nm) photic regime exhibited sensitivity to medium (max 540–560) and long (max 600 nm) wavelengths, while the OFF pathway exhibited peak sensitivity to only medium (max 540 nm) wavelength light. In a third population, where the the ambient light is moderately red-shifted (P50 629 nm), the ON pathway once again exhibited only a long wavelength sensitivity peak at 620 nm, while the OFF pathway exhibited sensitivity to both medium (max 560 nm) and long (max 600–620 nm) wavelength light. These findings suggest that the photic environment plays an integral role in shaping spectral sensitivity of the ON and OFF pathways.  相似文献   

2.
The fluorescence behavior of two tryptophans (Trp-134, Trp-213) in bovine serum albumin (BSA) and a single tryptophan (Trp-214) in human serum albumin (HSA) was examined. The maximum emission wavelength (max) was 340.0 nm for both proteins. In a solution of sodium dodecyl sulfate (SDS), the max of BSA abruptly shifted to 332 nm at 1 mM SDS and then reversed to 334 nm at 3 mM SDS. The max of HSA gradually shifted to 330 nm below 3 mM SDS, although it returned to 338 nm at 10 mM SDS. In contrast to this, in a solution of dodecyltrimethylammonium bromide, the max positions of BSA and HSA gradually shifted to 334.0 and 331.5 nm, respectively. Differences in the fluorescence behavior of the proteins are attributed to the fact that Trp-134 exists only in BSA, with the assumption that Trp-213 of BSA behaves the same as Trp-214 of HSA. The Trp-134 behavior appears to relate to the disruption of the helical structure in the SDS solution.  相似文献   

3.
Summary The left operator mutant v2s develops poorly during infection as a result of constitutive expression of the left operon. A revertant of v2s, designated iri, was found to contain an inversion of the cI region with the inversion endpoints to be within the lambda operators o L and o R. Formation of the inversion is facilitated by a translocation of right operator o R c mutant sequence to the left operator in v2s. The inversion in iri positions wild-type o R sequence at o L returning control of the left operon to repression by the lambda cro repressor.  相似文献   

4.
We report on the lens pigmentation and visual pigments of 52 species of demersal deep-sea fishes caught at depths ranging from 480 m to 4110 m in the Porcupine Seabight and Goban Spur area of the North-eastern Atlantic. Only one species, caught between 480 and 840 m, had a lens with large amounts of pigment, consistent with the hypothesis that heavily pigmented lenses in deep-sea fish serve to enhance the contrast of bioluminescent signals by removing much of the background radiance, which is only visible to fish living shallower than 1000 m. Low concentrations of lens pigmentation were also observed in a further two species (Rouleina attrita and Micromesisteus poutassou). The retinae of all species except five, contained only a single visual pigment, as determined by microspectrophotometry of individual rods, and/or spectrophotometry of retinal wholemounts and retinal extracts. Those fishes caught between 500 m and 1100 m had wavelengths of peak sensitivity (max) ranging from 476 nm to 494 nm, while most fish living below 1100 m tended to be more conservative with (max) values ranging from 475 nm to 485 nm. The only exceptions to this were three deep-living species caught between 1600 m and 2000 m whose retinae contain abnormally short-wave sensitive visual pigments (Cataetyx laticepsmax 468 nm; Alepocephalus bairdiimax 467 nm; Narcetes stomias max 472 nm), suggesting adaptation for the detection of short-wave bioluminescence.  相似文献   

5.
Summary Spectral sensitivity functions S() of single photoreceptor cells in 43 different hymenopteran species were measured intracellularly with the fast spectral scan method. The distribution of maximal sensitivity values (max) shows 3 major peaks at 340 nm, 430 nm and 535 nm and a small peak at 600 nm. Predictions about the colour vision systems of the different hymenopteran species are derived from the spectral sensitivities by application of a receptor model of colour vision and a model of two colour opponent channels. Most of the species have a trichromatic colour vision system. Although the S() functions are quite similar, the predicted colour discriminability curves differ in their relative height of best discriminability in the UV-blue or bluegreen area of the spectrum, indicating that relatively small differences in the S() functions may have considerable effects on colour discriminability. Four of the hymenopteran insects tested contain an additional R-receptor with maximal sensitivity around 600 nm. The R-receptor of the solitary bee Callonychium petuniae is based on a pigment (P596) with a long max, whereas in the sawfly Tenthredo campestris the G-receptor appears to act as filter to a pigment (P570), shifting its max value to a longer wavelength and narrowing its bandwidth. Evolutionary and life history constraints (e.g. phylogenetic relatedness, social or solitary life, general or specialized feeding behaviour) appear to have no effect on the S() functions. The only effect is found in UV receptors, for which max values at longer wavelengths are found in bees flying predominantly within the forest.  相似文献   

6.
Summary Scotopic visual pigments measured in the creek chub and the white sucker are porphyropsins with mean max values located at 538.3 and 536.5 nm, respectively. There is a shift of the max towards shorter wavelengths during the winter in both of these species coinciding with similar changes in the quality of downwelling light. max is significantly correlated to the P50 and spectrum width of the downwelling light and dissolved oxygen. An analysis of variance shows that there are significant differences between the max values of: fish in the two lakes, fish at different times, the two species at different times and fish in different lakes at different seasons. The offset visual pigments of both species appear to be well adapted to their photic environment in terms of the contrast hypothesis. This improvement of contrast detection is discussed in relation to their feeding habits.Abbreviations max wavelength at which absorbance is maximum - P50 wavelength which halves the total number of photons between 400 and 700 nm, a measure of spectral quality - PAR photosynthetically active radiation - MSP microspectrophotometric - SE standard error  相似文献   

7.
D. C. Morgan  R. Child  H. Smith 《Planta》1981,151(5):497-498
In background white light, supplementary far-red (max 700 nm) is an order of magnitude less effective than supplementary far-red (max 739 nm) in the stimulation of stem extension in Sinapis alba. The relationship between phytochrome photoequilibrium and extension rate increase for the two supplementary far-red treatments is, however, very similar. This evidence indicates that phytochrome cycling is not involved in the phytochrome control of stem extension in light-grown Sinapis alba and that the response to supplementary far-red light is not fluence rate (irradiance) dependent.Abbreviations Pfr far-red absorbing form of phytochrome - the phytochrome photoequilibrium (Pfr/Ptotal)  相似文献   

8.
Summary The relationship between the arrangement of cell events occurring in cambium in a definite configuration and the grain pattern of wood was investigated. Taking into consideration the growth activity of fusiform cell ends, a model of a migrating morphogenetic wave determining an event configuration was made. Waves of length =1 m for the periods T=2 years and T=3 years and waves of lengths =l m and =0.04 m for the period T=10 years were considered. On the model, events from successive annual rings, conventionally comprising 10 cell layers each, were summed. In this way, event maps were obtained. For wave =4 mm, the domain pattern on the modelled map was compatible with the grain pattern. The domain pattern for the wave =1 m was impossible to recreate because the wave migrated too fast. In this case, the pattern of event configuration, incompatible with the grain pattern, formed microareas, which were not domains.  相似文献   

9.
Summary Increment threshold measurements in wild rabbits give rise to spectral sensitivity curves that are unimodal or bimodal in nature, depending on the background luminance. We propose a model that explains the shape of these curves on the basis of synergistic and antagonistic interaction of blue cones (max = 425 nm), green cones (max = 523 nm) and rods (max = 498 nm).  相似文献   

10.
Summary A grpE mutation of Escherichia coli K12, which blocks DNA replication of the phage (Saito and Uchida, 1977), was mapped at 56 min on the standard genetic map. A transducing phage, grpE22, carrying the wild type allele of the grpE gene was constructed in vitro. Structures of grpE22 and its viable deletion derivatives were determined by electron microscopic analyses of appropriate heteroduplexes. Proteins coded by the bacterial DNA incorporated into the transducing phages were detected by two-dimensional gel electrophoresis. The results showed that the product of the grpE gene is a weakly acidic protein of molecular weight 24,000. Structural genes for two ribosomal proteins, rplS (L19) and rpsP (S16) were also shown to be carried by grpE22.  相似文献   

11.
Summary Lambda virC mutant, presumably an operator mutant for the operon including x, y, CII and O genes (Fig. 1), produce clearish plaque on a sensitive bacteria.Four revertants producing turbid plaques were isolated from virC and the mutational sites of which were studied. One (tw 1) is located very close to and on the left side of virC34, and another (tw 32) is at the almost same site of virC34. The others (tx 6 and tx 53) are located on the right side of virC34. tx recombinants have been isolated and characterized. These recombinants produce very turbid plaques and the rate of the repressor formation in the presence of CIts repressor is somewhat higher than that of wild type. tx develops very poorly after infection to sensitive cells but CItx develops normally. tx lysogens synthesize two to three times more exonuclease than the wild type lysogen. On a function of x region for the repressor formation and on a presence of a possible anti-repressor were discussed. The mutant tw 1 might be a promotor mutation of the CI-rex operon.This material has been published as an abstract in Jap. J. Genetics 45, 474 (1970).  相似文献   

12.
Summary Cyanobacteria (blue-green algae) and Rhodophyta (red algae) contain high concentrations of photosynthetic accessory pigments (phycobiliproteins) which trap light energy in the region between 400 and 650 nm. The electronic excitation energy is then transferred along a chain of these pigments to the reaction center chlorophyll of Photosystem II by a radiationless induced resonance process.Unlike the protein-chlorophyll complexes in the photosynthetic lamellae, the phycobiliproteins are readily soluble in aqueous solution, can be isolated in a variety of assembly forms, and crystallize readily. These properties facilitate the study of the structure of these proteins by chemical, physical, and immunological methods, as well as by X-ray diffraction and electron microscopy.The brilliantly colored phycobiliproteins are a homologous family of conjugated proteins of differing spectroscopic properties. The basic structural unit in these proteins is a monomer of 30,000–40,000 daltons made up of two dissimilar polypeptide chains, and . Each subunit carries covalently linked tetrapyrrole prosthetic groups related to the bile pigment biliverdin.The distinctive spectroscopic properties of each phycobiliprotein are a consequence of the chemical structure of the bile pigment it carries, and of the influence of the conformation and aggregation state of the protein on the spectra of these prosthetic groups. In vivo, the phycobiliproteins are organized into particles, phycobilisomes, attached in a regular array to the outer surface of the photosynthetic lamellae. Studies on phycobilisomes, and on intact cells, indicate the following pathway of energy transfer.Phycoerythrin Phycocyanin (max 560 nm) (max 620 nm) Allophycocyanin Allophycocyanin B (max 650 nm)(max 671 nm) Chlorophyll a (max 680 nm)The amounts of the various phycobiliproteins in the cell are influenced by the intensity and energy distribution of the incident radiation. The phenomena of intensity adaptation and complementary chromatic adaptation yield insights into the structure of phycobilisomes and the molecular basis of the plasticity of the structure of this light-harvesting system.Invited article.  相似文献   

13.
The visual pigments and photoreceptor types in the retinas of three species of Pacific salmon (coho, chum, and chinook) were examined using microspectrophotometry and histological sections for light microscopy. All three species had four cone visual pigments with maximum absorbance in the UV (max: 357–382 nm), blue (max: 431–446 nm), green (max: 490–553 nm) and red (max: 548–607 nm) parts of the spectrum, and a rod visual pigment with max: 504–531 nm. The youngest fish (yolk-sac alevins) did not have blue visual pigment, but only UV pigment in the single cones. Older juveniles (smolts) had predominantly single cones with blue visual pigment. Coho and chinook smolts (>1 year old) switched from a vitamin A1- to a vitamin A2-dominated retina during the spring, while the retina of chum smolts and that of the younger alevin-to-parr coho did not. Adult spawners caught during the Fall had vitamin A2-dominated retinas. The central retina of all species had three types of double cones (large, medium and small). The small double cones were situated toward the ventral retina and had lower red visual pigment max than that of medium and large double cones, which were found more dorsally. Temperature affected visual pigment max during smoltification.  相似文献   

14.
    
Summary The activity of the P gene product at various multiplicities of infection (m.o.i.) was examined in C 1 - conditions using an assay which measures the disappearance of the rapidly-sedimenting closed-circular (c.c) form of phage DNA. When cells were infected with C1857 at multiplicities of 5 phage/cell or less, between 65%–75% c.c. DNA was lost during incubation. If the multiplicity of infection was increased to 10 phage/cell or greater, a marked inhibition in the cleavage of c.c. DNA was observed.When bacteria were infected with either CI857CII2002 or CI857cro27 at low m.o.i., the usual 65%–75% decrease in the percentage of c.c. phage DNA occurred during incubation. In contrast, no losses in c.c. DNA were noted after infection with CI857cro27susP3. At high m.o.i., the cleavage of c.c. DNA was inhibited after infection with CI857CII2002, but not after infection with CI857cro27. It is concluded that at high m.o.i. in C 1 - infections, the expression of gene P is unaffected by the CII gene product, but is inhibited by the increased intracellular levels of cro protein.  相似文献   

15.
Birds have four spectrally distinct types of single cones that they use for colour vision. It is often desirable to be able to model the spectral sensitivities of the different cone types, which vary considerably between species. However, although there are several mathematical models available for describing the spectral absorption of visual pigments, there is no model describing the spectral absorption of the coloured oil droplets found in three of the four single cone types. In this paper, we describe such a model and illustrate its use in estimating the spectral sensitivities of single cones. Furthermore, we show that the spectral locations of the wavelengths of maximum absorbance (max) of the short- (SWS), medium- (MWS) and long- (LWS) wavelength-sensitive visual pigments and the cut-off wavelengths (cut) of their respective C-, Y- and R-type oil droplets can be predicted from the max of the ultraviolet- (UVS)/violet- (VS) sensitive visual pigment.  相似文献   

16.
The visual pigment and visual cycle of the lobster,Homarus   总被引:1,自引:0,他引:1  
Summary The visual pigment of the American lobster,Homarus americanus, has been studied in individual isolated rhabdoms by microspectrophotometry. Lobster rhodopsin has max at 515 nm and is converted by light to a stable metarhodopsin with max at 490 nm. These figures are in good agreement with corresponding values obtained by Wald and Hubbard (1957) in digitonin extracts. Photoregeneration of rhodopsin to metarhodopsin is also observed. The absorbance spectrum of lobster metarhodopsin is invariant with pH in the range 5.4–9, indicating that even after isomerization of the chromophore fromcis totrans, the binding site of the chromophore remains sequestered from the solvent environment. Total axial density of the lobster rhabdom to unpolarized light is about 0.7.As described for several other Crustacea, aldehyde fixation renders the metarhodopsin susceptible to photobleaching, a process that is faster at alkaline than at neutral or acid pH. Small amounts of a photoproduct with max at 370 nm are occasionally seen. A slower dark bleaching of lobster rhabdoms (1/2–2 h) also occurs, frequently through intermediates with absorption similar to metarhodopsin.The molar extinction coefficient of metarhodopsin is about 1.2 times greater than that of rhodopsin, each measured at their respective max. Isomerization of the chromophore fromcis totrans is accompanied by a change in the orientation of the absorption vector of about 3°. The absorption vector of metarhodopsin is either tilted more steeply into the membrane or is less tightly oriented with respect to the microvillar axes.When living lobsters are kept at room temperature, light adaptation does not result in an accumulation of metarhodopsin. At 4 °C, however, the same adapting lights cause a reduction of rhodopsin and an increase in metarhodopsin. There is thus a temperature-sensitive regeneration mechanism that supplements photoregeneration. Following 1 ms, 0.1 joule xenon flashes that convert about 70% of the rhodopsin to metarhodopsin in vivo, dark regeneration occurs in the living eye with half-times of about 25 and 55 min at 22 °C and 15 °C respectively.This work was supported by USPHS research grant EY 00222 to Yale University. S.N.B. was aided by NIH Postdoctoral Fellowship EY 52378.  相似文献   

17.
M. G. Holmes  E. Schäfer 《Planta》1981,153(3):267-272
Detailed action spectra are presented for the inhibition of hypocotyl extension in dark-grown Sinapis alba L. seedlings by continuous (24 h) narrow waveband monochromatic light between 336 nm and 783 nm. The results show four distinct wavebands of major inhibitory action; these are centred in the ultra-violet (max=367 nm), blue (max=446 nm), red (max=653 nm) and far-red (max=712 nm) wavebands. Previous irradiation of the plants with red light (which also decreases Ptot) causes decreased inhibitory action by all wavelengths except those responsible for the red light inhibitory response. Pre-irradiation did not alter the wavelength of the action maxima. It is concluded that ultra-violet and blue light act mainly on a photoreceptor which is different from phytochrome.Abbreviations B blue - D dark - FR far-red - HIR high irradiance reaction - HW half power bandwith - Pr R absorbing form of phytochrome - Pfr FR absorbing form of phytochrome - Ptot total phytochrome=Pr+Pfr - R red - UV ultra violet  相似文献   

18.
Electroretinogram (ERG) flicker photometry was used to study the spectral mechanisms in the retinas of white-tailed deer (Odocoileus virginianus) and fallow deer (Dama dama). In addition to having a rod pigment with maximum sensitivity (max) of about 497 nm, both species appear to have two classes of photopic receptors. They share in common a short-wavelength-sensitive cone mechanism having max in the region of 450–460 nm. Each also has a cone having peak sensitivity in the middle wavelengths, but these differ slightly for the two species. In white-tailed deer the max of this cone is about 537 nm; for the fallow deer the average max value for this mechanism was 542 nm. Deer resemble other ungulates and many other types of mammal in having two classes of cone pigment and, thus, the requisite retinal basis for dichromatic color vision.Abbreviations ERG electroretinogram - LWS long wavelength sensitive - MWS middle wavelength sensitive - SWS short wavelength sensitive  相似文献   

19.
The endophytic cyanobacterium, Anabaena azollae, isolated from laboratory cultures of Azolla caroliniana Willd., contains three spectroscopically distinct biliproteins. About 70% of the biliprotein is c-phycocyanin (max 610 nm) and 13% is allophycocyanin (max 647 nm, shoulder 620 nm). A third pigment corresponds to phycoerythrocyanin (max 570 nm, shoulder 590 nm). In very dilute solutions of allophycocyanin, at constant pH and buffer strength, the 647 nm maximum disappears and a single max occurs at 615–620 nm. The 647 nm absorption maximum reappears upon concentrating the dilute solution. Very dilute solutions of phycoerythrocyanin exhibit a broad peak between 570 and 590 nm. Absorption spectra of c-phycocyanin are not significantly altered upon dilution. Fluorescence emission maxima of phycoerythrocyanin, c-phycocyanin, and allophycocyanin occur at 630 nm, 643 nm and 660 nm respectively, using 540 nm excitation. Two subunits, of molecular weight 16,500 () and 20,600 (), are seen in c-phycocyanin upon dissociation with SDS. Dissociation of allophycocyanin and phycoerythrocyanin with SDS yields one sizeclass of subunits, with a molecular weight of about 17,500 for allophycocyanin and 18,000 for phycoerythrocyanin.Contribution No. 684 Offprint requests to: G. A. Peters  相似文献   

20.
Summary Bacteria with A-specific restriction plate unmodified phage with an efficiency of 10-2. One mutational event can produce restriction insensitive (sAo) mutants of . These differ from the original sA form of by no other property than their response to A-host specificity. Two-parental phage crosses involving sA and sAo, respectively, as non-selective marker allowed to map sA between genes cII and O. These data indicate that sA is the only site on DNA with affinity for A-specific restriction. DNA is thus an interesting substrate in in vitro A-specific restriction and modification. Using an assay based on the infectivity of DNA on helper-infected bacteria, A-specific modification activity was found in partially purified sonicates of bacteria with A-host specificity. In parallel to modification, 3H-methyl label from s-adenosylmethionine, the only cofactor required for modification, was transferred to unmodified DNA. No association of radioactivity was observed in control experiments with DNA from either modified ·A or from asAo mutant. These data suggest that A-specific modification is brought about by DNA methylation and that the sAo mutation not only abolished the affinity for A-specific restriction, but also for A-specific modification.  相似文献   

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