Effect of the rhenium additive to VOx/TiO2 and MoOx/TiO2 catalysts on their properties in oxidative dehydrogenation of propane

VO_x/TiO₂ and MoO_x/TiO₂ catalysts with the addition of Re (Re/V or Mo = 0.5) were synthetized and tested in oxidative dehydrogenation of propane and in reduction by propane. XPS measurements showed depletion of the surface in Re. The Re additive does not affect the total conversion of propane, but increases the selectivity to propene. The effect is more pronounced for the MoO_x/TiO₂ catalyst. The increase in the selectivity to propene is accompanied with the increase in the reducibility of the catalysts.     

PHOTOINDUCTION OF PHARBITIS FLOWERING: RELATIONSHIP TO RNA SYNTHESIS AND OTHER METABOLIC EVENTS

We have previously shown that a wave of enhanced uridine incorporation into RNA occurs in the more vegetative parts of the plumule at the end of the single dark period that evokes flowering in Pharbitis nil. We demonstrate here that a light break that suppresses flowering suppresses this wave as well. It does not shift the kinetics of the wave of uridine incorporation to a different time. The enhanced incorporation is into all RNA fractions. It had been concluded from excision experiments that the floral stimulus reaches the apex much after photoinduction. There is a metabolic shock caused by such excision of the cotyledons or surgical removal of the plumule that can suppress flowering if it is performed near the end of the inductive dark period. The terminal bud is more affected by this shock than lateral buds. Excision of the cotyledons enhances the rate of incorporation of exogenous uridine into the plumule. We propose that the “floral stimulus” stimulating incorporation into RNA reaches the plumule immediately after the end of the critical dark period.     

Lignin degrading ability of selected aspergillus Spp.

Most lignin research has been on wood-rot fungi and not on other lignolytic organisms. Members of the genusAspergillus inhabit lignin-rich environments, and we have studied their relative lignin-degrading potential.Aspergillus fumigatus, A. japonicus, A. niger, andA. terreus were tested for their ability to metabolize¹⁴C-labeled aromatic compounds. The species tested decarboxylated, demethoxylated, and cleaved the rings of coumaric, ferulic, vanillic, veratric, and anisic acids. More than 90% of C-ring-labeled ferulic and vanillic acids disappeared from the medium in 96 h of cultivation. More than half of the above was respired, the rest was incorporated in unknown form into the mycelium. Mycelia were homogenized and about 3% of the initial label was found in TCA precipitate of the cell-free supernatant. Protocatechuic acid 3,4-dioxygenase (EC 1.13.11.3) and catechol 1,2-dioxygenase (EC 1.13.11.1) activities were detected in the mycelial extracts of theAspergillus spp. All theAspergillus spp. were capable of degrading both aromatic and carbohydrate components of water-soluble lignocarbohydrate complexes (LCC) from wheat straw. The degradation of the aromatic moiety of soluble LCC with apparent molecular mass more than 100,000 daltons was far more active in theAspergillus spp. than in the whiterot fungi tested; i.e.Polyporus versicolor, Pleurotus ostreatus, andForties annosus. The aromatics present in the soluble LCC, as well as a variety of lignin-related compounds tested, did not affect the production of hemicellulases byA. japonicus. Aspergillus spp. degraded¹⁴C-dehydrogenative polymerizates, converting carbon from the ring as well as from the -O¹⁴CH₃ groups to¹⁴CCO₂.¹⁴CO₂ release after 21 d did not exceed 10% of the total¹⁴C input. This situation is comparable to some white-rot fungi. Lignosulfonate was poorly degraded byA. japonicus, but clearly modified.Fomes annosus was able to grow much better on lignosulfonate whenA. japonicus had previously grown on it.Aspergillus spp. grew efficiently on wheat straw, utilizing lignin and some carbohydrates, and rendering the remaining carbohydrates more available to attack of carbohydrases.     

INDUCTION OF Trichoderma SPORULATION BY NANOSECOND LASER PULSES: EVIDENCE AGAINST CRYPTOCHROME CYCLING

An important question in the study of photoreceptor action in morphogenesis is whether the chromophore is unidirectionally photobleached, or whether it is recycled, allowing each receptor molecule to be counted more than once. The common soil fungus Trichoderma harzianum grows vegetatively in the dark and sporulates in response to a pulse of blue or UV-A light. Colonies were grown at 26 degrees C, transferred to 3 degrees C, illuminated with non-saturating light, and then put back at 26 degrees C to sporulate. The fluence-response curves for photoinduction in the cold and at 26 degrees C were identical, indicating that there are no enzymatic transduction processes during irradiation. Regions of the perimeter of dark-grown colonies were given single pulses (maximum duration, 30 ns) at 355 nm with a neodymium laser. We obtained a complete fluence-response curve for the laser pulses, which agreed with data for irradiations in the second to minute range. Photoinduction at 3 degrees C, and validity of Bunsen-Roscoe reciprocity from nanoseconds to minutes, support the hypothesis that the inductive event is a simple first-order photobleaching reaction.     

LIGHT REQUIREMENTS FOR THE ENHANCED SYNTHESIS OF A PLASTID mRNA DURING SPIRODELA GREENING

A plastid mRNA (5 × 10⁵ mol wt) appears as a burst 3 h after white light greening of steady state dark grown plants of Spirodela oligorrhiza. In this species, chlorophyll synthesis begins after 12 h. The light requirement is different from the pulse of far-red reversible red light required to abolish the lag of chlorophyll synthesis in many species, including Spirodela. Continuous high energy far-red is not stimulatory. When the illumination is not continued throughout the time of incorporation, the stimulation is minimal. Low energy blue and red light are stimulatory, and green and far-red light are ineffectual. Blue light was > 5 times as effective as red light at many dose levels. Illumination with 3 × 10¹⁷ quanta/m²/s (50pEm/cm²/s) blue light at 476 nm gave about half maximum stimulation.     

CHARACTERIZATION OF THE 32,000 DALTON MEMBRANE PROTEIN—I. EARLY SYNTHESIS DURING PHOTOINDUCED PLASTID DEVELOPMENT OF SPIRODELA

The kinetics of ³⁵S methionine incorporation into soluble and membrane proteins during the transition from steady state dark growth to greening was studied in Spirodela. A sharp increase in the rate of incorporation occurred at 3 h, which was several h before major increases in chlorophyll were apparent. Part of this enhanced incorporation was due to enhanced synthesis of a 32 ,000 dalton membrane protein. This synthesis was paralleled by a temporal increase in in uitro template capacity for this protein and an increase in 0.5 × 10⁶ dalton plastid messenger RNA.     

Endogenous Retinoic Acid Required to Maintain the Epidermis Following Ultraviolet Light Exposure in SKH‐1 Hairless Mice

Ultraviolet light B (UVB) exposure induces cutaneous squamous cell carcinoma (cSCC), one of the most prevalent human cancers. Reoccurrence of cSCC in high‐risk patients is prevented by oral retinoids. But oral retinoid treatment causes significant side effects; and patients develop retinoid resistance. Exactly how retinoids prevent UVB‐induced cSCC is currently not well understood. Retinoid resistance blocks mechanistic studies in the leading mouse model of cSCC, the UVB‐exposed SKH‐1 hairless mouse. To begin to understand the role of retinoids in UVB‐induced cSCC we first examined the localization pattern of key retinoid metabolism proteins by immunohistochemistry 48 h after UVB treatment of female SKH‐1 mice. We next inhibited retinoic acid (RA) synthesis immediately after UVB exposure. Acute UVB increased RA synthesis, signaling and degradation proteins in the stratum granulosum. Some of these proteins changed their localization; while other proteins just increased in intensity. In contrast, acute UVB reduced the retinoid storage protein lectin:retinol acyltransferase (LRAT) in the epidermis. Inhibiting RA synthesis disrupted the epidermis and impaired differentiation. These data suggest that repair of the epidermis after acute UVB exposure requires endogenous RA synthesis.     

RHYTHMS IN BLUE-LIGHT-INDUCED CONIDIATION OF WILD TYPE AND A MUTANT STRAIN OF Trichoderma harzianum

Abstract— Trichoderma harzianum normally requires light for conidiation. Conidiation of colonies grown in continuous light does not appear to be rhythmic, but sharp banding patterns are formed under light/dark cycles. A single pulse of blue light produces a sharp band of conidia that forms where the growing edge of the mycelia is located at the time when the light is given. A period of about 24 h is required following the light pulse to produce mature conidia. During this time colonies are insensitive to further induction by light. The fluence required to produce 50% saturation varies by a factor of about 3 depending on when the pulse is given. This change of sensitivity is rhythmic with a period length of approximately 27 h when grown on medium containing deoxycholate.
The pattern of conidiation in a mutant strain (B119), which is able to form conidia in the dark, is rhythmic and the period length is dependent on the composition of the medium. Addition of deoxycholate to the medium increased the interval between dark bands from 12 to 24 h. The rhythmic banding is suppressed in constant light and a double banding pattern is produced in light/dark cycles. A pulse of blue light induces a band of conidia in this mutant, as in the wild type, but it also delays the reappearance of the dark banding pattern. The extent of this delay depends on when the pulse is given and, although the period length of the dark conidiation rhythm is affected by deoxycholate, the effect of blue light on its phase is not. Of the various rhythmic responses of Trichoderma studied here. the delay in reappearance of the dark banding pattern in B119 is the most promising for further detailed studies, for example of wavelength and temperature dependence.