Action spectra of the light-growth response in three behavioral mutants of Phycomyces

Null-point action spectra of the light-growth response were measured for three mutants of Phycomyces blakesleeanus (Burgeff) and compared with the action spectrum of the wild type (WT). The action spectrum for L150, a recently isolated night-blind mutant, differs from the WT spectrum. The L150 action spectrum has a depression near 450 nm and small alterations in its long-wavelength cutoff, the same spectral regions where its photogravitropism action spectrum is altered. This indicates that the affected gene product influences both phototropism and the light-growth response. For L85, a hypertropic (madH) mutant, the light-growth-response action spectrum is very similar to that of WT even though the photogravitropism action spectrum of L85 has been shown previously to be altered in the near-UV region. The affected gene product in this mutant appears to affect phototropic transduction but not light-growth-response transduction. The action spectrum of C110, a stiff (madE) mutant, differs significantly from the WT spectrum near 500 nm, the same spectral region where sporangiophores of madE mutants have been shown to have small alterations in second-derivative absorption spectra. This indicates that the madE gene product may be physically associated with a photoreceptor complex, as predicted by system-analysis studies.Abbreviations SE standard error of the mean - UV ultraviolet light - Wt wild type I dedicated to Masaki Furuya on the occasion of his 65th birthdayWe thank H. Reiner Schaefer for performing some of the experiments and for help in data analysis, David Durant for computer programming, and Benjamin Horwitz for helpful discussions. This work was supported by a grant from the National Institutes of Health (GM29707) to E.D. Lipson.     

Comparative studies on the specificity of anticlastogenic action in human lymphocytes in culture

Summary Comparative studies on human lymphocyte cultures yielded a certain specificity of the anticlastogenic action of the SH compounds 1-cysteine, cysteamine, and -aminoethylisothiouronium (AET) as well as of the amide 1-asparagine and the amino acid 1-methionine. This specific anticlastogenic activity manifested itself in specific changes of the spectrum of aberration types induced by the clastogens and of the pattern of intercellular distribution of the induced aberrations. It was clearly dependent on the concentration of the anticlastogens but was also influenced by the used clastogen. The use of different culture media yielded some quantitative influences on the anticlastogenic activity, but fundamental changes in the spectrum of anticlastogenic action have not been observed except with cysteamine. The patterns of activity ascertained for the different anticlastogens specifically differed from those changes in the spectrum and pattern of distribution of aberrations induced by a mere reduction of the concentration for instance of Trenimon. Therefore a direct reaction between the protectors and the clastogen Trenimon as the cause of the observed anticlastogenic action was again excluded. The presented data are also discussed under the aspects of the hypotheses of aberration induction as well as of their importance for further antimutagen research.Some parts of this paper have been supported by grants of Deutsche Forschungsgemeinschaft.     

The relationship between chlorophyll and the carotenoids in the algal flagellate,Euglena

1. We have obtained an action spectrum for chlorophyll formation in Euglena gracilis. This action spectrum is similar to the absorption spectrum of protochlorophyll. However, efforts to isolate and identify this pigment have been unsuccessful. 2. Porphyrins have been extracted from both the normal and dark-adapted Euglena and a chlorophyll-free mutant. 3. The "action" spectra for chlorophyll and carotenoid synthesis have been found to almost coincide, indicating that the same porphyrin-like molecule may influence the synthesis of both pigments. 4. It is indicated that two porphyrin-like systems are in operation simultaneously, one concerned with carotenoid "removal" and another involved in carotenoid and chlorophyll synthesis.     

The conformational states of cytochrome oxidase in the mitochondrion.

THE Soret spectrum of "resting" cytochrome oxidase in cytochrome-c depleted mitochondria has been determined. The spectrum obtained is dependent on the rate at which the oxidase is turning over. In the least active preparations, the spectrum is almost pure "oxidized" oxidase. With increasing activity the spectrum is converted to a mixture of "oxidized" and "oxygenated" oxidases. It is concluded that the same conformational differences between the two non-reduced forms that are found in the purified enzyme also occur in these cytochrome-c depleted mitochondria.     

Effect of LSD-25 on cholinesterases of the rat brain]

The indications for investigation on the LSD-25 "in vivo" activity on brain cholinesterases of the rat, have been considered. Indications of materials and method used have been supplied too. From the results obtained it emerged no clear evidence of a statistically significant inhibition of cholinesterases due to LSD-25. The results have been discussed and it has been evidenced that the lack of action of the psychotomimetic substance on cholinesterases could be only apparent or that the discrepancy between the LSD-25 anticholinesterase "in vivo" and "in vitro" action should be ascribed to the too scarce tissue levels which can be reached with the does utilized. Apart from the hypothesis, tending to explain the results obtained, it has been considered that the LSD-25 behavioural action, is not probably carried out thanks to a cholinesterase activity.     

藻红蛋白在微乳液中的增溶溶解

本文研究了藻红蛋白在油包水微乳液的紫外吸收和荧光光谱,结果表明,含藻红蛋白的阳离子表面活性剂的微乳液的光谱与其水溶液的光谱不同,说明藻红蛋白在这样的微环境中变性,与此相反,含藻红蛋白的阴离子表面活性剂的微乳液的光谱与其水溶液的相应光谱的特征峰相同,说明藻红蛋白在阴离子表面活性剂的微乳液中没有变性。本文进一步研究了含藻红蛋白的阴离子表面活性剂的微乳液在不同含水量时蛋白质的稳定性。并根据蛋白质的大小和     

Action Spectrum for Carotenogenesis in Myxococcus xanthus

An action spectrum was measured for photoinduction of colored carotenoids in dark-grown, early stationary-phase cells of Myxococcus xanthus. Maximum activity was observed at 405 to 410 nm with subsidiary maxima at 512, 533, 548, 585, and 635 nm. These maxima correspond closely in position and magnitude with absorption maxima of protoporphyrin IX, which had previously been isolated from M. xanthus cells and had been shown to increase during the stationary phase of the culture. Late stationary-phase, dark-grown cells undergo photolysis which had been shown to have an action spectrum resembling the absorption spectrum of protoporphyrin IX. The similarity of the action spectra of photolysis and photoinduced carotenogenesis in M. xanthus and of other photoinduced biological phenomena is discussed.     

纳他霉素毒性及生产研究进展

纳他霉素（Natamycin）是一种广谱的多烯大环内酯类抗真菌抗生素。由于它高效的抑茵效果而被广泛应用于食品防腐和真菌引起的疾病的治疗。对纳他霉素抗菌活性、作用机制、毒性、特别是当前纳他霉素的生产研究状况进行综述。     

Evidence of electrical potential changes in photophobically reacting blue-green algae

The correlation between photophobic responses and light-induced electric potential changes has been studied in the blue-green alga Phormidium uncinatum.

1. The photophobic reaction time depends on both length of preillumination and presentation time of stimulus. Under optimal conditions a reaction time of about 10 s has been determined.
2. Light-induced potential changes can be measured by means of external electrodes with a small gap between them bridged by a population of perpendicularly oriented trichomes. These potential changes follow a light-dark cycle with a lag phase of about 10 s.
3. The amplitude of these light-induced potential changes increases with light intensity until it reaches a saturation value of about 12 mV at 10000 lx. The action spectrum resembles the photophobic action spectrum with peaks in the absorption region of C-phycoerythrin and chlorophyll a.

The significance of light-induced potential changes as a means of sensory transduction for photophobic responses in blue-green algae is being discussed.     

Antimicrobial potential of alkalophilic micromycetes <Emphasis Type="Italic">Emericellopsis alkalina</Emphasis>

The ability of alkalophilic micromycetes of the Emericellopsis alkalinа to produce antimicrobial peptides has been studied. Evaluation of the spectrum and the yield of antibiotic compounds has allowed us to choose a promising producer of peptide antimycotics, Emericellopsis аlkalinа А118. The producer exhibits antifungal activity against conditionally pathogenic yeast and mold fungi, i.e., Candida аlbicans, Aspergillus niger, and A. fumigatus. The group of homologous active compounds isolated by the set of identified structural features (molecular weight, the ratio of the absorption at certain wavelengths, and the absence of initiation of Edman sequencing) may be attributed to peptaibols, which are a group of nonribosomal membrane-active antimicrobial peptides with a specificity of action primarily against fungi-micromycetes.     

Design,synthesis and herbicidal activity of new iron chelating motifs for HPPD-inhibitors

HPPD (p-hydroxyphenylpyruvate dioxygenase) is a herbicidal target that all major companies active in plant protection research have worked on intensely in the last decade. Several modern herbicides with this mode of action have been introduced recently, or are currently in development. The activity of all commercialized HPPD-inhibitors is based on a chelating functionality, which binds to the redoxactive iron center in the enzyme. In the course of our research, leading to the new broad spectrum corn herbicide topramezone by BASF, this chelating functionality has been examined thoroughly, and many new chelating motifs have been synthesized. The chelating motif N–O in combination with CO, which is known for its iron-binding potential from many natural siderophores, was especially promising. Examination of several different motifs of this type resulted in the identification of benzoyl-N-hydroxyimidazoles, which inhibited the HPPD-enzyme with potency comparable to the best known systems. Significant herbicidal activity in the greenhouse could also be identified for some of these compounds, but this activity was weaker than for the analogous benzoylpyrazolones of the topramezone-type.     

The pore-forming action of polyenes: From model membranes to living organisms

The incidence of resistant fungal pathogens has been increasing, especially in immuno-compromised people. As such, considerable research has been focused on discovering anti-fungal agents with new mechanisms of action and on optimizing the use of existing agents. In this context, interest in the polyene group of anti-fungals has recently been renewed, since they are known to be effective against a broad spectrum of fungal pathogens that only rarely develop a resistance to them. In the past 10?years considerable efforts have been made to improve their efficacy and, simultaneously, to reduce their toxicity. Knowledge about the basic mechanisms of their action will be of crucial importance to further optimizing their use. The mechanisms of polyene action at the membrane level are reviewed here, focusing primarily on their pore-forming activity and on the resulting osmotic responses of artificial lipid vesicles and different eukaryotic cells.     

Inhibition of aggregation by light in the cellular slime mold Dictyostelium discoideum

Aggregation of Dictyostelium amoebae is inhibited by light. White light intensities 10² W · cm^-2 cause an inhibition which reaches a saturation at 2 · 10³ W · cm^-2. The action spectrum, based on photon fluence-response curves, shows a major peak around 405 nm and extends through most of the visible spectrum with a secondary maximum at about 530 nm. The action spectrum of the inhibition of aggregation resembles the action spectrum of accumulations of amoebae in light traps and the action spectrum of photodispersal from light traps; it does not resemble the action spectrum of phototaxis in pseudoplasmodia.     

pH-induced alterations in the structure and activity of cytochrome c oxidase

The effects of pH on the activity and structure of beef heart cytochrome c oxidase have been studied in the pH range 5.0-7.6. (i) A group with pK of approximately 5.45 has been readily detected in the pH vs. activity curve. This group must be deprotonated to achieve maximal activity. (ii) A group with a similar pK (5.45) has been detected and contributes to the spectral character of the reduced oxidase. Over the range pH 5.0-7.6 no other acid-sensitive group contributes to the spectrum of the reduced oxidase. (iii) The oxidized oxidase shows at least three acid-sensitive groups contributing to the spectrum. One occurs in the pH 7 range and another in the pH 5.6 range; below pH 5.2 additional pH-sensitive groups are apparent. Accurate estimation of the pK's of the groups responsible for the spectral changes in the oxidized oxidase has not been possible. (iv) The spectrum of the "oxygenated" (428 nm) conformer of the oxidized protein is invariant over the range ph 5.5-7. (v) The changes occurring in the spectrum of the purified oxidase also occur in the protein contained in phospholipid vesicles. (vi) The data are discussed in terms of the mechanism by which the oxidase, during its in situ catalytic cycle, may give rise to the primary events in energy coupling.     

Action spectrum for cryptochrome-dependent hypocotyl growth inhibition in Arabidopsis

Cryptochrome blue-light photoreceptors are found in both plants and animals and have been implicated in numerous developmental and circadian signaling pathways. Nevertheless, no action spectrum for a physiological response shown to be entirely under the control of cryptochrome has been reported. In this work, an action spectrum was determined in vivo for a cryptochrome-mediated high-irradiance response, the blue-light-dependent inhibition of hypocotyl elongation in Arabidopsis. Comparison of growth of wild-type, cry1cry2 cryptochrome-deficient double mutants, and cryptochrome-overexpressing seedlings demonstrated that responsivity to monochromatic light sources within the range of 390 to 530 nm results from the activity of cryptochrome with no other photoreceptor having a significant primary role at the fluence range tested. In both green- and norflurazon-treated (chlorophyll-deficient) seedlings, cryptochrome activity is fairly uniform throughout its range of maximal response (390-480 nm), with no sharply defined peak at 450 nm; however, activity at longer wavelengths was disproportionately enhanced in CRY1-overexpressing seedlings as compared with wild type. The action spectrum does not correlate well with the absorption spectra either of purified recombinant cryptochrome photoreceptor or to that of a second class of blue-light photoreceptor, phototropin (PHOT1 and PHOT2). Photoreceptor concentration as determined by western-blot analysis showed a greater stability of CRY2 protein under the monochromatic light conditions used in this study as compared with broad band blue light, suggesting a complex mechanism of photoreceptor activation. The possible role of additional photoreceptors (in particular phytochrome A) in cryptochrome responses is discussed.     

In vitro antifungal activity of voriconazole: New data after the first years of clinical experience

Voriconazole has been developed to meet the increasing need for new and useful antifungal agents for the treatment of invasive mycoses. This review describes the spectrum of voriconazole antifungal activity based on data from in vitro studies published during the last three years. This survey demonstrates that voriconazole has a broad antifungal spectrum against the most common fungal pathogens being its action fungistatic for Candida and fungicidal for Aspergillus and other filamentous fungi. Overall, more than 95% of all Candida isolates tested are susceptible to voriconazole and less than 3% are resistant. Similar or even better activity rates have been described for Aspergillus, Cryptococcus and most of yeasts and moulds of medical importance. We also discuss the limitations related to the azole cross-resistance observed in some Candida glabrata isolates, the poor activity of voriconazole against Scedosporium prolificans, its activity against fungal biofilms and the great potential usefulness of combination of voriconazole with other antifungal drugs.     

Structure and Function of the Euglenoid Eyespot: THE PROBABLE LOCATION OF THE PHOTOTAXIS PHOTORECEPTOR

With Euglena gracilis neither the action spectrum for photokinesisnor that for phototaxis corresponds to the absorption spectrumof the stigma, as has been previously claimed. The phototaxisaction spectrum may be interpreted instead as a combinationof the photokinesis action spectrum, stigma absorption spectrum,and chloroplast absorption spectrum. This supports the contentionthat the paraflagellar body rather than the stigma is the probablephotoreceptor of the eyespot apparatus, and indicates that boththe stigma and chloroplasts provide the directional ‘lightscreen’. It also suggests that the absorption spectrumof this photoreceptor is the photokinesis action spectrum.     

Dantrolene inhibits halothane-induced membrane reorganization A study using 31P-NMR and differential scanning calorimetry

The action of the relaxing agent dantrolene on dipalmitoylphosphatidylcholine (DPPC) model membranes in the presence and absence of the general anesthetic halothane has been investigated by DSC and 31P-NMR. Dantrolene has a weak effect on both the thermodynamic and NMR parameters of the pure model membrane. When halothane is present in the system, the relaxing agent acts to counterbalance the strong anesthetic-induced membrane perturbation. This is reflected in DSC experiments by a change of the enthalpy variation (delta H) and of the main gel-to-fluid phase transition temperature (Tc) towards the values of the pure lipid system. The amount of halothane-induced small tumbling vesicles, as detected by 31P-NMR by the superposition of an isotropic line on a lamellar-type powder spectrum, is considerably reduced upon dantrolene addition. This means that the relaxing agent "cures" the membrane de-structuring action promoted by halothane. Membranes first treated with dantrolene are also protected from the halothane perturbation. So, the relaxing agent is both "curative" and "preventative" against halothane. The optimum effect is obtained for 1 dantrolene molecule per ca 34 halothane molecules. The mechanisms of action were discussed in relation to membrane fluidity.     

Interpretation of EMG spectral alterations and alteration indexes at sustained contraction.

Alterations of the electromyographic power spectrum have been studied extensively to assess fatigue development in the neuromuscular system. Usually, a data reduction has been applied to create an index based on the mean power frequency or the median frequency. The physiological origin of the spectrum alterations has been (and to some extent still is) incompletely known. However, during the 1980s, substantial progress has been made in this field. The factors affecting the electromyographic power spectrum discussed in this review are action potential velocity decrease, firing statistics alterations, action potential modification, muscle temperature, additional recruitment at fatigue, and force level. Their impact on three commonly used fatigue indexes, mean power frequency, median frequency, and zero crossing rate, is also reviewed.     

Second positive phototropism in the Avena coleoptile

A method has been developed whereby the second positive phototropism can be observed separately from the first positive and negative phototropic responses which also occur in oat coleoptiles. Although the second positive phototropic response has often been referred to as the base response, photoreception for it is shown to occur mainly in the apical 3 mm of the coleoptile. The Bunsen-Roscoe reciprocity law, so typical of first positive phototropism, does not apply to the second positive responses, and the amount of curvature increases linearly with the duration of the stimulus. However, although this linear proportionality between stimulus duration and response is the major factor determining response at all intensities tested, the intensity of the stimulus does influence the response somewhat. The action spectrum for the response shows no activity above 510 nm and has peaks at 375 and 450 nm. In all but one particular it closely resembles the action spectrum for the first positive phototropism, and it is concluded that the same, or similar, pigments may well be the photoreceptors for both types of response. The identity of this blue light absorbing pigment is not known.