The Spectral Distribution of Firefly Light

The in vivo emission spectra of sixteen species of Jamaican fireflies and four species of American fireflies have been measured with a photoelectric recording spectrometer. A simple technique of stimulation with ethyl acetate vapor was found to elicit bright continuous emission over a period of several minutes. Although the luciferin-luciferase cross-reactions were positive in all cases tested, peak intensity wavelengths show distinct species differences, ranging from 5520 to 5820 A. Widely separated emission peaks arise from the thoracic and abdominal organs respectively in the same animal, the click-beetle, Pyrophorus.     

Spectral Distribution of Light in a Tobacco Canopy and Effects of End-of-Day Light Quality on Growth and Development

Shifts in spectral distribution of light were determined within and below a canopy of field-grown burley tobacco (Nicotiana tabacum L. cv. Burley 21). The leaves transmitted much far red light relative to red and blue light. Thus, shaded leaves received more far red light, relative to red and blue, than was received by unshaded leaves. Under field conditions, tobacco plants within rows grew taller than did those at the west end of rows.     

Uric Acid Spherulites in the Reflector Layer of Firefly Light Organ

Background

In firefly light organs, reflector layer is a specialized tissue which is believed to play a key role for increasing the bioluminescence intensity through reflection. However, the nature of this unique tissue remains elusive. In this report, we investigated the role, fine structure and nature of the reflector layer in the light organ of adult Luciola cerata.

Principal Findings

Our results indicated that the reflector layer is capable of reflecting bioluminescence, and contains abundant uric acid. Electron microscopy (EM) demonstrated that the cytosol of the reflector layer''s cells is filled with densely packed spherical granules, which should be the uric acid granules. These granules are highly regular in size (∼700 nm in diameter), and exhibit a radial internal structure. X-ray diffraction (XRD) analyses revealed that an intense single peak pattern with a d-spacing value of 0.320 nm is specifically detected in the light organ, and is highly similar to the diffraction peak pattern and d-spacing value of needle-formed crystals of monosodium urate monohydrate. However, the molar ratio evaluation of uric acid to various cations (K⁺, Na⁺, Ca²⁺ and Mg²⁺) in the light organ deduced that only a few uric acid molecules were in the form of urate salts. Thus, non-salt uric acid should be the source of the diffraction signal detected in the light organ.

Conclusions

In the light organ, the intense single peak diffraction signal might come from a unique needle-like uric acid form, which is different from other known structures of non-salt uric acid form. The finding of a radial structure in the granules of reflector layer implies that the spherical uric acid granules might be formed by the radial arrangement of needle-formed packing matter.     

The Spectral Response of Light Dependent Chlorophyll b Formation

Dark grown seedlings of barley will obtain a high ratio chlorophyll a/chlorophyll b when exposed to intermittent light (1 min of incandescent light or one electronic flash every hour). Such material has been exposed to monochromatic light of different wavelengths for 1 h. The ratio a/b gets a minimum in light of 670 nm, indicating the highest rate of chlorophyll b formation at this wavelength. The possibility is discussed that the light absorber (and also precursor) could be a short-lived chlorophyll a form, existing prior to the forms in the Shibata-shift. Chlorophyll b formation in darkness is discussed from the findings that the rate of formation of chlorophyll b is higher in intermittent light than it should be, calculated from the rate in continuous light, where the saturation intensity is rather low.     

Phytochrome and Seed Germination. IV. Action of Light Sources With Different Spectral Energy Distribution on the Germination of Tomato Seeds

Germination of tomato seeds exposed to a single, saturating irradiation from light sources of different spectral energy distribution seems to be dependent upon the photostationary P_FR/P_R ratio established by the irradiation. Germination of tomato seeds exposed to prolonged irradiations from the same light sources does not seem to be controlled solely by the P_FR/P_R ratio induced and maintained by the irradiation.     

混农林业生态系统内部的光能分布

林农混作中作物相互影响,除了争夺土壤肥力以外,主要是争夺光能。光能的合理分布是取得林粮双丰收的前提。分析生态系统内部光能分布的方法很多,但主要有两种:一是分析由于树木遮荫造成的光照时间的减弱,二是     

The green hemoproteins of bovine erythrocytes. II. Spectral, ligand-binding, and electrochemical properties

The two green hemoproteins isolated from bovine erythrocytes (form I and form II) have been characterized as to spectral, electrochemical, and chemical properties. The absorption spectra of the isolated hemoproteins are typical of high spin ferric states. Reduction of the hemoproteins yields high spin ferrohemoproteins. Complexation of the ferrohemoproteins with CO and the ferrihemoproteins with cyanide yields low spin complexes, demonstrating the presence of an exchangeable weak field ligand in both the ferrous and ferric states of the hemoproteins. The differences in position and intensity of the absorption peaks of the visible spectra allow the two forms to be distinguished from one another. The midpoint potential of forms I and II were found to be +0.075 and +0.019 V, respectively, at pH 6.4 and +0.038 and -0.005 V, respectively, at pH 7.0. This is consistent with the gaining of 1 proton/electron during the reduction. The Nernst plot reveals an unusual 0.5-electron transfer, whereas a quantitative titration demonstrates a 1-electron transfer. Form I binds cyanide more tightly than form II (KD of 84 and 252 micrometer, respectively). The observed spectral, electrochemical, and ligand-binding differences between forms I and II can be explained in terms of a greater electron-withdrawing ability of the side chains of the heme of form I relative to the heme of form II.     

Spectral Engineering Via Complex Patterns of Circular Nano-Object Miniarrays: II. Concave Patterns Tunable by Integrated Lithography Realized by Circularly Polarized Light

Plasmonics - The use of circularly polarized beams in interferometric illumination of colloid sphere monolayers enables the direct fabrication of rectangular patterns composed of circular nanohole...     

Morphogenesis in Schizophyllum commune. II. Effects of Monochromatic Light

The photoinduction of fruiting bodies by light of defined wavelengths was studied in the fungus Schizophyllum commune Fr. Several properties of the induction were established. (1) The exposure-response relationship for induced fruiting was determined for light of 448 nm. (2) The Bunsen-Roscoe Law of Reciprocity was found to hold for the photoinduction of fruiting bodies for the interval 36 to 2000 sec with light of 448 nm. (3) Light of wavelengths from 320 nm to 525 nm induced fruiting bodies. Although the photoreceptor is unknown, it may be a flavin rather than a carotenoid, because light in the near ultraviolet (350 nm-400 nm) was inductive. (4) Neither red light (660 nm) nor far-red light (730 nm) induced fruiting bodies or affected the sensitivity of the fungus toward photoinduction by blue light (448 nm).     

Spectral Analysis of Laser Light Scattered from Motile Microorganisms

The theoretical basis of laser scattering from motile microorganisms is examined. Spectra of swimming particles are compared with spectra arising from brownian motion. For mixtures of motile and resting organisms, that part of the spectrum related to the motile organisms is enhanced when V_s/|k|D is large, where V_s is the mean swimming speed of the motile microorganisms,|k| is the Bragg wave vector, and D is the diffusion coefficient of the nonmotile particles. When the directed motion of swimming microorganisms persists for periods which are much longer than τ = (|k|V_s)^-1, the scattering spectrum is given as S(k, ω) ∞ (| [ω - ω₀]/k|), where is the probability distribution obtained by two-dimensional integration over the swimming speed distribution. A computation of scattering from bull spermatozoa, based on published velocity distributions, is investigated in detail.     

Stomatal Diffusion Resistance of Snap Beans. II. Effect of Light

The effect of light on the stomatal resistance of abaxial and adaxial leaf surfaces of snap beans (Phaseolus vulgaris L.) was studied in the growth chamber and in the field. The adaxial stomata required more light to open than the abaxial stomata; the abaxial stomatal apertures were still about 50% open at 1% full sunlight and light-induced closure was never observed under daytime field conditions. A given value of abaxial stomatal resistance was obtained at a given illumination of the abaxial guard cells whether illumination was adaxial or abaxial.     

Physiological Studies on Pea Tendrils. II. The Role of Light and ATP in Contact Coiling

Excised pea (Pisum sativum L.) tendrils incubated in the light coil more than those incubated in the dark. This light effect, which displays spectral responses characteristic of chlorophyll-mediated mechanisms, is increased by at least 8 hours of prior dark incubation of plants from which the tendrils were derived. Considerable evidence indicates a major role of ATP in coiling. For example, inhibitors of ATP production decrease contact coiling. Exogenous ATP increases curvature in the dark, whereas exogenous adenosine, AMP and ADP are practically without effect. The ATP effect can be reversed by the addition of sucrose to the bathing solution. Tendrils of plants placed in the dark overnight have lower ATP levels than those held in the light. One half hour after stimulation, the endogenous ATP level of tendrils on plants kept in the light decreased fourfold. In the same period, the endogenous inorganic phosphate level increased markedly, indicating high adenosine triphosphatase activity.     

The role of lymphokine-activated cell-associated antigen. II. Distribution and correlation with cell cycle

It has previously been shown that killer-blocking monoclonal antibody (KBA MAb) recognizes lymphokine-activated cell-associated antigen (LAA) involved in broad-reactive killer. (BRK) cell-mediated cytotoxicity. We now report that LAA is expressed on all lymphoid cells, though the amount of LAA on unstimulated lymphocytes is low. In contrast, lymphocytes activated in vitro with either concanavalin A, alloantigens, lipopolysaccharide, or recombinant interleukin 2 express high levels of LAA. In addition, in vivo activated lymphocytes, such as OK-432-activated lymphocytes and tumor-infiltrating lymphocytes express higher levels of LAA than unstimulated lymphocytes. We also demonstrate that the expression of LAA is restricted in T-cell lymphomas and a M phi cell line, while myelomas, fibrosarcomas, and carcinomas do not express LAA. Cell cycle analysis using propidium iodide and KBA MAb showed that LAA expression was closely correlated with the transition of cells from G1a to G1b phase.