Functional group richness: implications of biodiversity for light use and lipid yield in microalgae

Currently, very few studies address the relationship between diversity and biomass/lipid production in primary producer communities for biofuel production. Basic studies on the growth of microalgal communities, however, provide evidence of a positive relationship between diversity and biomass production. Recent studies have also shown that positive diversity–productivity relationships are related to an increase in the efficiency of light use by diverse microalgal communities. Here, we hypothesize that there is a relationship between diversity, light use, and microalgal lipid production in phytoplankton communities. Microalgae from all major freshwater algal groups were cultivated in treatments that differed in species richness and functional group richness. Polycultures with high functional group richness showed more efficient light use and higher algal lipid content with increasing species richness. There was a clear correlation between light use and lipid production in functionally diverse communities. Hence, a powerful and cost‐effective way to improve biofuel production might be accomplished by incorporating diversity related, resource‐use‐dynamics into algal biomass production.     

Relative effectiveness and interaction of ultraviolet-B, red and blue light in anthocyanin synthesis of apple fruit

The effect of light on anthocyanin production in apple ( Malus pumila Mill. cv. Jonathan) skin disks was investigated, with prolonged irradiation from different light sources. High fluence rates of white light provided from a xenon lamp were unable to produce large amounts of anthocyanin, and anthocyanin production became saturated at about 30 W m⁻². When UV-B light, provided by a fluorescent lamp which had an emission peak at 312 nm, was combined with the white light, anthocyanin production was synergistically stimulated and increased up to the highest fluence rates of white light tested (44 W m⁻²). This UV-B light was more effective than red and blue light provided from fluorescent lamps, but anthocyanin production became saturated at about 1.7 W m⁻². However, simultaneous irradiation with red and UV-B light had a synergistic effect. UV-B light was also effective in increasing anthocyanin production in whole fruit. Therefore this synergism seemed to have an important role in the development of the desirable red skin color under field light conditions. The results of aminoethoxyvinylglycine treatment suggested that ethylene was not involved in the stimulative effect of UV-B light.     

Interactions Between Light and Gas Vacuoles in Halobacterium salinarium Strain 5: Effect of Ultraviolet Light

The potential light shielding by intracellular gas vacuoles in Halobacterium salinarium strain 5 was examined by looking at the ultraviolet light inactivation curves of both wild-type cells and mutants which are defective in the production of gas vacuoles. Whereas strains defective in gas vacuole production were slightly more sensitive to ultraviolet inactivation, no significant differences in ultraviolet sensitivity were seen, indicating that these subcellular inclusion bodies are not effective as light-shielding organelles. In addition, it was shown that ultraviolet light acts as a plasmid-curing agent in Halobacterium.     

Events Surrounding the Early Development of Euglena Chloroplasts: I. Induction by Preillumination 1

Preillumination, followed by a dark period prior to exposure of dark-grown nondividing cells of Euglena gracilis var. bacillaris to normal lighting conditions for chloroplast development, results in potentiation, or abolishment of the usual lag in chlorophyll accumulation. The degree of potentiation is a function of the length of the preillumination period, the intensity of preilluminating light, and the length of the dark period interposed before re-exposure to continuous light for development. The optimal conditions are found to be: 90 minutes of preillumination with white light at an intensity greater than 30 microwatts per square centimeter (14 foot candles) followed by a dark period of at least 12 hours. Reciprocity is not found between duration and intensity of preilluminating light. Preillumination with blue light and red light was found to be the most effective in promoting potentiation, and the ratio of effectiveness of blue to green to red is consistent with protochlorophyll-(ide) being the photoreceptor. Although red light is effective, there is no reversal by far red light, and these facts, taken together with the effectiveness of blue light, suggest that the phytochrome system is not involved. The amount of chlorophyll formed at the end of preillumination is proportional to the resulting potentiation, suggesting that the amount of protochlorophyll(ide) removed or chlorophyll(ide) formed regulates this phenomenon. Potentiated and nonpotentiated cells show comparable rates of protochlorophyll(ide) resynthesis, suggesting that this is not the limiting factor in nonpotentiated cells. Although light is required for protochlorophyll(ide) conversion in chlorophyll synthesis, a brief preillumination seems also to initiate the production of components in the subsequent dark period which, in nonpotentiated cells, are ordinarily synthesized during the lag period under continuous illumination. These components are necessary to sustain maximal rates of subsequent chlorophyll accumulation.     

Effect of light and nutrition on fruiting ofAscobolus biguttulatus

The influence of light and nutrition on fruit body development inAscobolus biguttulatus was studied. High C and N concentrations inhibited sexual reproduction. A wide variety of carbon sources supported the production of fertile apothecia. Among the nitrogen sources, urea and asparagine were the best, while inorganic salts resulted in very poor fruit body production. Light was an absolute requirement for apothecial production. When photoinduction was accomplished by single 24-h periods, the colonies were most receptive at the 5^th day of growth. Among types of light, near ultraviolet light was the most effective.     

Sporulation of Plasmopara viticola: Differentiation and Light Regulation

Abstract: The development of grape downy mildew (Plasmopara viticola) was followed histologically during the entire latent period until the appearance of mature sporangia. Production of sporangiophores and sporangia was assessed using low-temperature scanning electron (LTSEM) and fluorescent light microscopy. Time-course studies using attached leaves of Vitis vinifera cv. Müller-Thurgau revealed that the production of sporangiophores and sporangia is a highly coordinated process and is completed within 7 h. As this differentiation is assumed to occur only in darkness, the influence of light was investigated. For this purpose, different light regimes were applied to infected leaf discs of V. vinifera cv. Müller-Thurgau. White light irradiation prevented formation of sporangia, although the growth of the mycelium was not affected. Many sporangiophores were observed that were abnormally shaped, i.e., short hyphae in clusters or thin, extremely elongated hyphae. For the formation of mature sporangia, a prolonged dark period was necessary. Light experiments suggest photosensitivity at the end of the latent period. A terminal white light irradiation caused an inhibitory effect, whereas a final phase of darkness promoted sporangium development. Different light qualities were tested, revealing an inhibition of sporangium development by blue light whereas neither red nor far-red light were effective.     

Geographical Distribution of Adolescent Body Height with Respect to Effective Day Length in Japan: An Ecological Analysis

The height of Japanese youth raised in the northern region tends to be greater than that of youth raised in the southern region; therefore, a geographical gradient in youth body height exists. Although this gradient has existed for about 100 years, the reasons for it remain unclear. Consideration of the nutritional improvement, economic growth, and intense migration that has occurred in this period indicates that it is probably the result of environmental rather than nutritional or genetic factors. To identify possible environmental factors, ecological analysis of prefecture-level data on the body size of 8- to 17-year-old youth averaged over a 13-year period (1996 to 2008) and Japanese mesh climatic data on the climatic variables of temperature, solar radiation, and effective day length (duration of photoperiod exceeding the threshold of light intensity) was performed. The geographical distribution of the standardized height of Japanese adolescents was found to be inversely correlated to a great extent with the distribution of effective day length at a light intensity greater than 4000 lx. The results of multiple regression analysis of effective day length, temperature, and weight (as an index of food intake) indicated that a combination of effective day length and weight was statistically significant as predictors of height in early adolescence; however, only effective day length was statistically significant as a predictor of height in late adolescence. Day length may affect height by affecting the secretion of melatonin, a hormone that inhibits sexual and skeletal maturation, which in turn induces increases in height. By affecting melatonin production, regional differences in the duration of the photoperiod may lead to regional differences in height. Exposure to light intensity greater than 4000 lx appears to be the threshold at which light intensity begins to affect the melatonin secretion of humans who spend much of their time indoors.     

Enhancement of firefly luciferase activity by cytidine nucleotides.

The temporal pattern of light production by firefly luciferase depends on the ATP concentration. With low concentrations of ATP a constant production of light occurred while at high concentrations of ATP (greater than 10 microM) there was a flash of light followed by a decline in light production. This time course of light production with high ATP concentrations was changed from the flash pattern to a pattern with a constant production of light by several cytidine nucleotides. CTP, CDP, dCTP, dCDP, dideoxyCTP, periodate-oxidized CTP and CDP, and the etheno derivatives of CTP and CDP produced that change. CMP, cytidine, CDP-glycerol, CDP-glucose, CDP-ethanolamine, and benzoylbenzoylCTP either were inhibitory to firefly luciferase or were not effective in changing the flash time course. Coenzyme A and related compounds also changed the time course of light production. The changes in time course produced by either cytidine nucleotides or CoA were inhibited by desulfoCoA. These compounds apparently enhanced light production by promoting the dissociation of the inhibitory product, oxidized luciferin, from the enzyme. When the activating compounds were used with high concentrations of ATP, the sensitivity of assay for firefly luciferase was increased. This increased sensitivity is important when using the firefly luciferase gene as a reporter.     

Flowering in Pisum: the Effect of Light Quality on the Genotype If e Sn Hr

Far-red light, when given as a 16 h photoperiod extension, iamore effective than red light in reducing the flowering nodeof genotype Pisum. In contrast, when a 16 h dark period is interruptedby a 2 h light break red light is more effective than far-redlight. In addition, the stimulatory effect of a red interruptionis partially reversed by a subsequent period of far-red. However,a light interruption is not effective until over 12 h have elapsedsince the start of the previous photoperiod, regardless of whetherthe photoperiod was of 4 or 8 h duration. The results suggest that there are two light-dependent reactionscontrolling flowering in peas, one operating through the phytochromesystem with high levels of Pfr suppressing production of flowerinhibitor by the sn gene and a second requiring continuous illuminationwith wavelengths above 700 nm. The role of time measurementin the photoperiod response in peas is suggested to be filledby the proportion of time the Sn gene is effectively producinginhibitor. The photoperiod response in peas is not independentof temperature or plant age since the activity of gene Sn isalso varied by these factors.     

Blue, red and blue plus red light control of chloroplast pigment and pigment-proteins in corn mesophyll cells: Irradiance level-quality interaction

Corn ( Zea mays L. cv. OP Golden Bantum) was grown under low irradiance blue, red or blue plus red light. Red was more effective than blue light for synthesis of Chl a, b and light-harvesting proteins (LHC-2) associated with photosystem 2(PS2). Blue light was slightly more effective for synthesis of light-harvesting proteins (LHC-1) associated with photosystem 1 (PS1), but below a fluence rate of 1 μmol m⁻² s⁻¹ the response to blue vs that to red depended on irradiance level. Blue light containing a small amount of red light was as effective as red light for Chl a and b synthesis, but no more effective than blue light for LHC-2 synthesis. Adding small amounts of blue light to red repressed the effect of red light on LHC-2 synthesis and produced irradiance response curves similar to those produced by blue alone for LHC-2 synthesis. This repression by blue light depended on the ratio of red to blue and the level of the blue light.     

Concurrent saccharification/fermentation of enzymatic corn syrups in light beer production

The high degree of fermentability required in light beer production can be achieved by concurrent saccharification and fermentation of a wort containing an enzyme prepared corn syrup adjunct and glucoamylase. Traditional acid or acid-enzyme syrups used as adjuncts in regular beer production are not effective in a concurrent saccharification/fermentation process due to the presence of oligosaccharides that are resistant to the action of glucoamylase.     

Visible and near-IR light induced biohydrogen production using the system containing Mg chlorophyll-a from Spirulina and colloidal platinum

Photoinduced hydrogen production with Mg chlorophyll-a from Spirulina as a visible and near-IR light photosensitizer by use of three component system consisting of nicotineamide adenine dinucleotide phosphate, reduced form (NADPH) as an electron donor, methylviologen as electron relay reagent and colloidal platinum as hydrogen production catalyst was investigated. After 4 h irradiation, the amount of hydrogen production with Mg chlorophyll-a and MgTPP, which was artificial model compound for chlorophyll, were c.a. 2.7 and 1.8 mol, respectively. When the near-IR light was irradiated, little change of hydrogen production was observed. Thus, the effective visible and near IR light induced hydrogen production system with colloidal platinum was established using Mg chlorophyll-a.     

Cat's claw inhibits TNFalpha production and scavenges free radicals: role in cytoprotection

Cat's claw (Uncaria tomentosa) is a medicinal plant from the Amazon River basin that is widely used for inflammatory disorders and was previously described as an inhibitor of NF-kappaB. Cat's claw was prepared as a decoction (water extraction) of micropulverized bark with and without concentration by freeze-drying. Murine macrophages (RAW 264.7 cells) were used in cytotoxicity assays (trypan blue exclusion) in response to the free radical 1, 1-diphenyl-2-picrilhydrazyl (DPPH, 0.3 microM) and ultraviolet light (UV) light. TNFalpha production was induced by lipopolysaccharide (LPS 0.5 microg/ml). Cat's claw was an effective scavenger of DPPH; the EC(50) value for freeze-dried concentrates was significantly less than micropulverized (18 vs. 150 microg/ml, p <.05). Cat's claw (10 microg/ml freeze-dried) was fully protective against DPPH and UV irradiation-induced cytotoxicity. LPS increased TNFalpha media levels from 3 to 97 ng/ml. Cat's claw suppressed TNFalpha production by approximately 65-85% (p <.01) but at concentrations considerably lower than its antioxidant activity: freeze-dried EC(50) = 1.2 ng/ml, micropulverized EC(50) = 28 ng/ml. In conclusion, cat's claw is an effective antioxidant, but perhaps more importantly a remarkably potent inhibitor of TNFalpha production. The primary mechanism for cat's claw anti-inflammatory actions appears to be immunomodulation via suppression of TNFalpha synthesis.     

Factors controlling the production of domoic acid by Pseudo-nitzschia (Bacillariophyceae): A model study

A mechanistic model has been developed to explore the factors controlling the production of domoic acid (DA) by the pennate diatom Pseudo-nitzschia. The idealized model allows consideration of the uncoupling between photosynthesis and growth, while DA production has been set as a secondary metabolism sharing common precursors with growth. Under growth limitation, these precursors can accumulate, resulting in an increased DA production. The model was first evaluated based on its ability to simulate the observed DA production by either silicon (Si) or phosphorus (P) limited batch cultures of Pseudo-nitzschia available in the literature. Sensitivity tests were further performed to explore how the ambient nutrients and the light regime (intensity and photoperiod length) are possibly directing the Pseudo-nitzschia toxicity. The general pattern that emerged is that excess light, in combination with Si or P limitation, favours DA production, provided nitrogen (N) is sufficient. Model simulations with varying nutrient stocks supporting Pseudo-nitzschia blooms under non-limiting light suggest two potential ways for nutrients to control DA production. First, N excess in comparison to available Si and P relieves DA production from its limitation by N, an absolute requirement of the DA molecule. Second, increased nutrient stocks amplify the DA production phase of the blooms (in addition to enhancing Pseudo-nitzschia biomass) which leads to an even more toxigenic bloom. Simulations investigating the light regime suggest a light threshold below which an important delay in DA production could be expected in Pseudo-nitzschia cultures. In the natural environment, the monitoring of light conditions during Pseudo-nitzschia blooms might help to anticipate the magnitude of the toxic event. Pseudo-nitzschia toxicity is indeed linked to the excess of primary carbon that accumulates during photosynthesis under growth limitation by nutrients.     

Culture of the green microalga Botryococcus braunii Showa with LED irradiation eliminating violet light enhances hydrocarbon production and recovery

The green microalga Botryococcus braunii (B. braunii), race B, was cultured under light-emitting diode (LED) irradiation with and without violet light. This study examined the effect of violet light on hydrocarbon recovery and production in B. braunii. C34 botryococcene hydrocarbons were efficiently extracted by thermal pretreatments at lower temperatures when the alga was cultured without violet light. The hydrocarbon content was also higher (approximately 3%) in samples cultured without violet light. To elucidate the mechanism of effective hydrocarbon recovery and production, we examined structural components of the extracellular matrix (ECM). The amounts of extracellular carotenoids and water-soluble polymers extracted by thermal pretreatment from the ECM were decreased when the alga was cultured without violet light. These results indicate that LED irradiation without violet light is more effective for hydrocarbon recovery and production in B. braunii. Furthermore, structural ECM components are closely involved in hydrocarbon recovery and production in B. braunii.     

A new screening method to detect water-soluble antioxidants: acetaminophen (tylenol®) and other phenols react as antioxidants and destroy peroxynitrite-based luminol-dependent chemiluminescence

This study is based on a simple chemical interaction of peroxynitrite (ON O O⁻) and luminol, which produces blue light upon oxidation. Since peroxynitrite has a half-life of about 1 s, a drug known as linsidomine (SIN-1) is used as a peroxynitrite generator. Peroxynitrite can oxidize lipids, proteins and nucleic acids. Upon the stimulation of inflammation and/or infection, macrophages and neutrophils can be induced to produce large amounts of peroxynitrite, which can oxidize phenols and sulphhydryl-containing compounds. Therefore, phenols and sulphhydryls eliminate peroxynitrite. This is an example of the Yin–Yang hypothesis e.g. oxidation–reduction. Acetaminophen (Tylenol®) can inhibit fever and some types of pain without being a particularly effective anti-inflammatory. Since it is a phenol, it could act as a nitration target for peroxynitrite. Then peroxynitrite, the possible cause of pain and elevated temperature, might be destroyed in the reaction. Acetaminophen is a phenolic compound which produces a clear inhibitory dose–response curve with peroxynitrite in its range of clinical effectiveness. Whether acetaminophen actually works as we suggest is to be proven. Three different types of reaction could decrease the amount of peroxynitrite: (a) interference with base-catalysed opening of the SIN-1 molecule; (b) destruction of one or both substances needed to form it— superoxide and/or nitric oxide; when the SIN-1 degrades to superoxide and nitric oxide, the former may be destroyed by superoxide dismutase (SOD); (c) peroxynitrite may react directly with phenols (mono-, di-, tri- and tetraphenols), possibly by nitration. Nordihydroguaiaretic acid and 2-hydroxyestradiol (catechol estrogen) are potent inhibitors of luminol light emission. Epineprine, isoproterenol, pyrogallol, catechol and ascorbic acid (a classic antioxidant) are all inhibitors of luminol chemiluminescence. Isoproterenol, norepinephrine/and epinephrine first inhibit light but overall stimulate the light production. Initially, SIN-1 degrades to produce peroxynitrite, which reacts with luminol to produce blue light. If any of three catecholamines are present with the reaction that produces light, there is an initial inhibition of light production, and then a marked stimulation. A possible reason for this is that these catechols are oxidized and the metabolized phenol stimulates the production of light from luminol. Also, during oxidation of catecholamines superoxide is sometimes formed, which could stimulate production of peroxynitrite. This simple screening system is introduced to find useful antioxidants against peroxynitrite. © 1998 John Wiley & Sons, Ltd.     

The photophores of Meganyctiphanes norvegica (M. Sars) (Euphausiacea): mode of operation

The photophores of Meganyctiphanes were investigated with regard to the control of light production and with respect to their role in a hitherto unknown communication system using light flashes which became evident from observation of specialised signalling behaviour. To that purpose the light production was recorded during presentation of a range of stimuli delivered to the intact, tethered shrimp. Stimuli used were changes in ambient light, water turbulence, simulated predator approach and light flashes, as well as electric shocks and serotonin injections. Strong negative light gradients, exaggerating the natural sunset signal, reliably elicited light production, the peak of which lasted on average 2 min. In the late phase of this light production, low frequency water oscillations and turbulent flow (assumed intraspecific communication signals at close range) elicited transient increases in light production. Artificial light flashes presented to a group of shrimp evoked a signalling behaviour in which the animal points the light of its photophore beamers (positioned at the ventral side and normally directed downwards) for a fraction of a second at observers within the same depth level. The responses produced by the signalling behaviour indicate a fixed delay with respect to the triggering flash. Electric stimulation of the ventral nerve cord via implanted electrodes resulted in a strong light production with a latency of 160 ms. Injection of serotonin, resulting in haemolymph concentrations of 10^–5 M and higher, initiated increasingly strong and increasingly long-lasting continuous light production. Implications for the control of the photophores are discussed. Electronic Publication     

Effect of culture conditions on canthaxanthin production by Dietzia natronolimnaea HS-1

This study investigated the effects of various culture parameters (carbon sources, temperature, initial pH of culture, NaCl concentration, and light) on the growth and canthaxanthin production by Dietzia natronolimnaea HS-1. The results showed that the most effective carbon source for growth and canthaxantin production was glucose, and the best pH and temperature were 7 and 31 degrees C, respectively. In addition, the biomass and canthaxanthin production increased in a medium without NaCl and in the presence of light. Under the optimized conditions, the maximum biomass, total carotenoid, and canthaxanthin production were 6.12 +/- 0.21 g/l, 4.51 +/- 0.20 mg/l, and 4.28 +/- 0.15 mg/l, respectively, in an Erlenmeyer flask system, yet increased to 7.25 g/l, 5.48 mg/l, and 5.29 mg/l, respectively, in a batch fermenter system.     

Abscission: characterization of light control

Exposure of mung bean (Vigna radiata [L.] Wilczek cv Jumbo) cuttings to low level red light inhibits dark-induced leaf abscission. A 12-hour daily light requirement for maximum inhibition of abscission was equally effective as a continuous red light treatment or shorter light-dark cycles. Transfer of cuttings from dark to light stopped the abscission process at the time of transfer. The available evidence suggests a light receptor located in the leaves with an abscission inhibitor translocated from lighted leaf to the abscission zone.     

不同培养条件和前体对蛹虫草液体发酵产虫草素的影响

蛹虫草能产生虫草素等多种活性物质。为考察不同液体发酵方式及添加前体物质对虫草素积累的影响,选用蛹虫草08Y1菌株,通过光照振荡、光照静置、黑暗振荡、黑暗静置四种培养条件和添加前体物质（腺嘌呤1g/L+甘氨酸16g/L）,发酵16d后检测虫草素和腺嘌呤含量。结果表明：08Y1菌株在黑暗振荡培养条件下,虫草素积累达1,015.0mg/L,腺嘌呤利用率达98.5%,说明黑暗振荡培养并添加前体物质是提高虫草素产量的有效方法。