Pigment Analysis Research Articles

Integrating phytoplankton pigment and DNA meta‐barcoding observations to determine phytoplankton composition in the coastal ocean

AbstractQuantifying phytoplankton composition is critical to predicting marine ecosystem structure and function. DNA meta‐barcoding and high‐performance liquid chromatography (HPLC) pigment analysis are two widely used methods for assessing phytoplankton composition; however, comparing their performance has been done only rarely. Here, we integrate DNA meta‐barcoding and HPLC pigment observations to determine eukaryotic phytoplankton composition in the Santa Barbara Channel, California. We find that both methods identify the same four dominant eukaryotic phytoplankton taxa (diatoms, dinoflagellates, chlorophytes, and prymnesiophytes), but inter‐ and intra‐lineage variability in biomarker pigmentation (associated with both a lack of taxonomic specificity of biomarker pigments and intrinsic differences in accessory pigmentation) drives substantial disagreement between the methods. Covariation network analysis circumvents this disagreement and reveals that diverse assemblages of phytoplankton and other protists covary with distinct suites of biomarker pigments. Our results highlight the strengths and weaknesses of each method in characterizing phytoplankton composition and reveal novel insights into phytoplankton physiology that could only be gained by integrating the two methods. Finally, we suggest a path to monitor eukaryotic plankton communities on unprecedented spatiotemporal scales based on the covariation of unique phytoplankton and protistan assemblages with remotely sensible phytoplankton pigment concentrations.

Grapevine leaf physiology and morphological characteristics to elevated CO2 in the VineyardFACE (Free air Carbon dioxide Enrichment) experiment.

Atmospheric carbon dioxide (CO2) concentration has continuously increased since pre-industrial times and has currently reached an average growth rate of 2.3 ppm per year. For the majority of plant species elevated CO2 (eCO2) improves photosynthesis and thus plant biomass production. To investigate the effects of eCO2 on leaf physiology and morphological leaf characteristics two Vitis vinifera L. cultivars, Riesling and Cabernet Sauvignon, grown in the VineyardFACE (Free Air Carbon dioxide Enrichment) system were used. The VineyardFACE is located at Geisenheim, Rheingau comparing future atmospheric CO2-concentrations (eCO2, predicted for the mid-21st century) with current ambient CO2-conditions (aCO2). Experiments were operated under rain-fed conditions for two consecutive years (2015 and 2016). For both varieties and CO2 treatments, leaf gas exchange measurements were performed as well as measures of epidermal flavonoid (Flav) and leaf chlorophyll (Chl) indices by using a portable leaf clip. Furthermore, leaves were sampled for spectrophotometric analysis of the leaf pigments chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoid (Car). Additionally, leaf cross-sections were produced as permanent preparations to investigate morphological characteristics of the leaf structure. Both cultivars did not differ in leaf chlorophyll meter readings or leaf pigments between the two CO2 treatments while net assimilation was highly stimulated under elevated CO2 for both seasons. Differences found in leaf cross-sections were detected in palisade parenchyma and epidermal thickness of Cabernet Sauvignon under eCO2, whereas Riesling net assimilation increased by 40% under a 20% CO2 enrichment while remaining unaffected in different leaf layer thickness. The observed results within grapevine leaf tissues provide insights to seasonal adaptation strategies of grapevines under elevated CO2 concentrations predicted in future.

Comparative transcriptome and miRNA analysis of skin pigmentation during embryonic development of Chinese soft-shelled turtle (Pelodiscus sinensis)

BackgroundAquatic animals show diverse body coloration, and the formation of animal body colour is a complicated process. Increasing evidence has shown that microRNAs (miRNAs) play important regulatory roles in many life processes. The role of miRNAs in pigmentation has been investigated in some species. However, the regulatory patterns of miRNAs in reptile pigmentation remain to be elucidated. In this study, we performed an integrated analysis of miRNA and mRNA expression profiles to explore corresponding regulatory patterns in embryonic body colour formation in the soft-shelled turtle Pelodiscus sinensis.ResultsWe identified 8 866 novel genes and 9 061 mature miRNAs in the skin of Chinese soft-shelled turtles in three embryonic stages (initial period: IP, middle period: MP, final period: FP). A total of 16 563 target genes of the miRNAs were identified. Furthermore, we identified 2 867, 1 840 and 4 290 different expression genes (DEGs) and 227, 158 and 678 different expression miRNAs (DEMs) in IP vs. MP, MP vs. FP, and IP vs. FP, respectively. Among which 72 genes and 25 miRNAs may be related to turtle pigmentation in embryonic development. Further analysis of the novel miRNA families revealed that some novel miRNAs related to pigmentation belong to the miR-7386, miR-138, miR-19 and miR-129 families. Novel_miR_2622 and novel_miR_2173 belong to the miR-19 family and target Kit and Gpnmb, respectively. The quantification of novel_miR_2622 and Kit revealed negative regulation, indicating that novel_miR_2622 may participate in embryonic pigmentation in P. sinensis by negatively regulating the expression of Kit.ConclusionsmiRNA act as master regulators of biological processes by controlling the expression of mRNAs. Considering their importance, the identified miRNAs and their target genes in Chinese soft-shelled turtle might be useful for investigating the molecular processes involved in pigmentation. All the results of this study may aid in the improvement of P. sinensis breeding traits for aquaculture.

Color Paintings of Taiping Heavenly Kingdom Royal Residence: An Analytical Study

Color paintings have much aesthetic value and historical importance. This study examined the color paintings of the east pillar of the Taiping Heavenly Kingdom’s Great Hall. The pillars in interiors of ancient buildings were painted with a layer of red lacquer. The painted pillars are valuable because they symbolize the highest rank of a building’s hierarchy and the esteemed status of the owner. In this study, we investigated pigments, inorganic fillers, and adhesives used in the color paintings of the royal residence. Energy dispersive X-ray spectrometry, polarized light microscopy, and Raman spectroscopy were used to investigate the pigments of the paintings. Pyrolysis–gas chromatography–mass spectrometry (Py–GC/MS) was used to classify the composition of adhesives. The results showed that the painted pigments included vermilion (HgS), graphite (C), white lead (2PbCO3·Pb(OH)2), and lead red (Pb3O4). The Py–GC/MS showed possible presence of tung oil and flour in the mortar. The X-ray diffraction demonstrated the presence of limewater and brick dust (gismondine, dolomite). The analyses of pigment, inorganic fillers, and adhesives of the Taiping royal palace paintings provide information on the long-standing preservation of the paintings.

Editor’s Introduction

Editor’s Introduction

From the Collection

Mark Catesby’s primary role in making “Natural History of Carolina” is undeniable, but to what extent was he involved in creating the map and natural history illustrations? Unlike previous studies comparing different sets of the first edition to identify significant variations among illustrations that might reflect participation of multiple artists, we delve deeply into variations within a single set in the Winterthur Library. Using close visual scrutiny and instrumental pigment analysis to understand Catesby’s collaborative process reveals multiple hands in the production of the map, creation of the intaglio copper plates, and coloration of the prints.

Are cyanobacteria a nearly immortal source of high market value compounds?

AbstractBACKGROUNDWhen the human population increases, so does the need to explore a wider range of feedstocks and biomasses, such as cyanobacteria. However, a deeper understanding of the growth patterns and pigment production is required to support the selection of the most beneficial species and conditions for industrial production. The growth and pigment production (i.e., chlorophyll a and C‐phycocyanin) of three cyanobacterium species were evaluated following a three‐fold aim. The first goal was to compare among a species commonly selected for exploitation (Arthrospira platensis) and two alternative species (Anabaena cylindrica and Nostoc muscorum). The second goal was analyzing pigment production in the long‐term. The last goal involved comparing different methods (spectrophotometry and fluorimetry) to understand whether there is an appropriate proxy of biomass increase and pigment production that can be used for monitoring purposes.RESULTSAll species showed high longevity and proved capable of growing for more than 100 days without any additional supplementation. However, the maximum quantum yield of PS II (Fv /Fm ) revealed that their photosynthetic efficiency varied over time with a clear decrease after 2 months. Pigment analysis showed a heterogeneous pattern during the growth periods of all three species that could only be captured by the parameter Fv /Fm, but the pattern was only present for A. cylindrica and N. muscorum in some stages of the culture period.CONCLUSIONN. muscorum was found to be the best chlorophyll a and C‐phycocyanin producer, with the production peaking for all species at defined time periods within the growth profile. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Non-invasive mineral analysis of pigments of wall paintings in the Sungseonjeon Hall

Non-invasive mineral analysis of pigments of wall paintings in the Sungseonjeon Hall

Extreme harmful algal blooms, climate change, and potential risk of eutrophication in Patagonian fjords: Insights from an exceptional Heterosigma akashiwo fish-killing event

The Patagonian fjords have experienced intense harmful algal blooms (HABs) in the last decade, affecting important aquaculture areas in southern Chile. Climatic anomalies have recently triggered ‘super blooms’ of opportunistic toxic microalgal genera, especially due to persistent thermal stratification which likely provides an optimal niche for HABs development in fjord systems. In March-April 2021, an intense and widespread bloom of the raphidophyte Heterosigma akashiwo caused high salmon mortalities (>6,000 t) in the Comau fjord, Los Lagos Region. A climate variability analysis showed the effects of the positive phase of the Southern Annular Mode (SAM > 1.2 hPa) overcame those of La Niña (Niño3.4 = -0.9 °C) leading to an intense drought on the northern part of Patagonia with record low rainfall (the 2nd driest summer in the last 70 years) and increased water temperature. A regional satellite analysis revealed an extreme and persistent shallow Mixed Layer Depth (MLD) during summer periods since 2019 within the inland seas. In situ vertical fine-resolution measurements during the bloom event showed high cell abundances in the first 3 m of the water column (max. ∼ 70,000 cells mL−1), associated with warmer water temperature (∼15.5 – 17.5 °C), low salinity (∼25–30 psu), moderate to high dissolved oxygen (5 – 8.5 mg/L) and extremely high fluorescence signals in dense superficial cell aggregations (max. 74.9 µg/L). A 18S rRNA metabarcoding analysis formally confirmed the presence of H. akashiwo and its almost monospecific bloom development at the water surface. HPLC pigment analysis showed the carotenoid fucoxanthin in high proportion (48.8 %) compared to other photosynthetic pigments, becoming a potential pigment biomarker for early satellite H. akashiwo detection. Cell growth and cytotoxic in vitro experiments revealed high phenotypic plasticity of Chilean H. akashiwo against sudden changes in salinity. An RTgill-W1 gill cell assay revealed high cytotoxic activity (viability down to ∼ 50 – 30 % of controls) only at high cell abundances (>40,000H. akashiwo cells mL−1), which was in accordance with histological examination of moribund salmon that showed gill damage and circulatory disorders mainly due to long-term exposure to hypoxic conditions and not to potent cytotoxic effects. The Party-MOSA particles dispersion model revealed a high retention of water masses within the Comau fjord during the H. akashiwo outbreak, a scenario that may have boosted fish kills due to enhanced cells patchiness, ichthyotoxins persistence and hypoxic conditions. A historical dissolved inorganic nutrient data analysis showed that inner Patagonian fjords maintain low N and P concentrations including those environments considered of high eutrophication risk. Low N:P (<16:1) ratios measured at Comau fjord during the 2021 suggests that toxic flagellates growth could be favored over diatoms; however, low N:Si (<1:1 – N deficiency) evidences a clear need for better understanding of the role of mixotrophy in the persistence of the 2021H. akashiwo bloom for several weeks. These results highlight the fact that HABs responses against climate drivers and potential eutrophication are not universal and need to be assessed yearly and locally, particularly because extreme droughts and intensive aquaculture in northern Patagonia are expected to continue throughout the 21st century.

Transcriptomic Analysis Suggests a Coordinated Regulation of Carotenoid Metabolism in Ripening Chili Pepper (Capsicum annuum var. conoides) Fruits.

Carotenoids are not only photosynthetic and photoprotective pigments in plants, but also essential antioxidative nutrients for human health. The fruit is the main plant organ that synthesizes and sequestrates carotenoids. Fruit ripening is a complicated developmental process, during which the rewiring of the metabolic network is tightly coordinated with the re-organization of cellular and organellular structures. Chili pepper (Capsicum annuum) is one of the major crops that accumulates a distinct level of carotenoids, especially capsanthin, in their ripened fruits. To elucidate how different metabolic and developmental scenarios are regulated in ripening chili pepper fruits, we analyzed the carotenoid profiles and transcriptomes of fruits at different ripening stages. Our pigment analysis indicated an opposite correlation between the contents of carotenoid species with β,β-structures (e.g., β-carotene, zeaxanthin, and capsanthin) and of lutein with the β,ε-structure, whereas lutein displayed a high correlation with chlorophylls during ripening. From the chili pepper Zunla-1 genome, a full repertoire of 38 homologous genes encoding enzymes in the carotenoid biosynthetic pathway was identified. The fluctuations in their transcript abundances during ripening suggested different involvement of these genes in the regulation of carotenoid biosynthesis. We further searched genes of which the expression showed high correlations with the accumulation of β-carotene during the ripening process. Moreover, from the transcriptomic analysis, a total of 17 transcription factors that co-expressed with different groups of carotenoid biosynthetic genes were identified.

Concentration and distribution of phytoplankton nitrogen and carbon in the Northwest Atlantic and Indian Ocean: A simple model with applications in satellite remote sensing

Despite the critical role phytoplankton play in marine biogeochemical cycles, direct methods for determining the content of two key elements in natural phytoplankton samples, nitrogen (N) and carbon (C), remain difficult, and such observations are sparse. Here, we extend an existing approach to derive phytoplankton N and C indirectly from a large dataset of in-situ particulate N and C, and Turner fluorometric chlorophyll-a (Chl-a), gathered in the off-shore waters of the Northwest Atlantic and the Arabian Sea. This method uses quantile regression (QR) to partition particulate C and N into autotrophic and non-autotrophic fractions. Both the phytoplankton C and N estimates were combined to compute the C:N ratio. The algal contributions to total N and C increased with increasing Chl-a, whilst the C:N ratio decreased with increasing Chl-a. However, the C:N ratio remained close to the Redfield ratio over the entire Chl-a range. Five different phytoplankton taxa within the samples were identified using data from high-performance liquid chromatography pigment analysis. All algal groups had a C:N ratio higher than Redfield, but for diatoms, the ratio was closer to the Redfield ratio, whereas for Prochlorococcus, other cyanobacteria and green algae, the ratio was significantly higher. The model was applied to remotely-sensed estimates of Chl-a to map the geographical distribution of phytoplankton C, N, and C:N in the two regions from where the data were acquired. Estimates of phytoplankton C and N were found to be consistent with literature values, indirectly validating the approach. The work illustrates how a simple model can be used to derive information on the phytoplankton elemental composition, and be applied to remote sensing data, to map pools of elements like nitrogen, not currently provided by satellite services.

Phenotyping of basil (Ocimum basilicum L.) illuminated with UV-A light of different wavelengths and intensities

The effects of light on plants depend on the energy dose and spectral characteristics. We investigated how UV-A radiation with two different wavelengths, 365 and 385 nm, combined at different intensities as supplemental light to red-blue baseline illumination affects growth and selected physiological and biochemical traits of green leaf basil (Ocimum basilicum L.). Conventional physiological measurements and biochemical analyses of photosynthetic pigments and phenolics were combined with high-throughput phenotyping. We did not detect any negative effects of UV-A on plant growth and photosynthetic functions, even at high doses of short-wave UV-A. Furthermore, thylakoid processes were enhanced under UV-A, as evidenced by higher electron transport rates and increased photochemical efficiency. The increase in anthocyanin index (ARI) indicates the UV-screening response. However, no anthocyanins were detected in the leaves, and the only phenolic compounds that responded to UV-A were hydroxycinnamic acid derivatives, which have a dual function in responding to UV-A (UV protection and antioxidants). UV-A increased the pool of xanthophyll cycle pigments and their ratio to chlorophylls. All this prevents photoinhibition and contributes to a high plasticity/efficiency of the basil's response to light environment.

Scientific study of the pigments and binders used in mural painting from the 16th‐century ce St Mary's Church of Cheriapally, Kottyam, Kerala, and its relevance to conservation

AbstractThe aim of this investigation was to analyze the materials and techniques of the paintings in the 16th‐century ce St Mary's Church, to evaluate deterioration of the paintings, and to propose a suitable conservation treatment for their preservation. The material analysis of ground, pigments, binders, and plasters was undertaken using binocular microscopy, field emission scanning electron microscopy (SEM)–energy dispersive X‐ray spectroscopy, X‐ray fluorescence, Fourier transform infrared spectroscopy in reflectance (KBr) and transmittance mode (attenuated total reflection), thin‐film X‐ray diffraction, and micro‐Raman spectroscopy. Gas chromatography–mass spectrometry (GC‐MS) was used for identifying proteinaceous and lipidic materials extracted from the micro‐samples. The study generated data on two different red and green pigments used as decorative materials. The red pigments were identified as cinnabar along with traces of hematite and clay minerals, and green as malachite and the minor presence of other minerals. SEM analysis identified cotton fiber embedded in the coarse plaster layer that provided better strength to the plaster. Plant oils and proteins found as the binder in the pigment samples suggested that the painting technique was executed as tempera. Lead white and gypsum materials were used in previous restoration works.

A Study on Painting Characteristics by Analysis of Pigments Used in Unhangak Hall Dancheong in Hwaryeongjeon Shrine, Suwon

A microscopy investigation has been performed together with non-destructive component analysis to verify properties of pigments used in Unhangak Hall Dancheong in Hwaryeongjeon Shrine, Suwon. In addition, X-ray diffraction analysis, polarization microscopy, and scanning electron microscopy analyses were performed on the pigment specimens collected at the site. Dividing the Unhangak interior into areas and performing pigment property analyses has confirmed that the pigments Jusa, Jangdan, and Sukganju (iron oxide, red ocher) have been used for red colors. Jahwang, Gold, and Gamboge (organic pigments) have been used for yellows, the pigments Hayeob, Seokrok, Neorok, Samrok, and Chrome green have been used for greens, and Seogcheong and Heocheong have been used for blues. Baekto, Yeonbaek, Hobun, and Chalk have been used for whites, and Meog has been used for black. The inclusion of Chrome green (a modern pigment) among the pigments used to produce the Dancheong of Unhangak Hall has been confirmed. With this one exception, traditional pigments have been used. One unique property of the dancheong decorating Unhangak Hall include the use of higher than ordinary proportions of Jusa and Hayeob than is ordinarily found in traditional buildings. Another distinction is that expensive pigments including Seogcheong, Heocheong, Seokrok, Jusa, Jahwang, Gold, and Hayeob have been intensively used in worship spaces including the center compartment (Jeongkan) and Nae-hap. These pigments have been used over a coating of white primer (mostly Baekto, Yeonbaek, Hobun or Chalk) to improve choromaticity and color vibrance.

Studi Komposisi Pigmen Makro Alga (Gelidium corneum) yang Berasal Dari Pantai Yakoba Kota Jayapura

Macroalgae or also known as seaweed is a low-level plant that does not have true roots, stems and leaves. The function of the roots, stems and leaves is replaced by the thallus. The purpose of this study was to study the composition of macroalgae pigments (Gelidium corneum) originating from Yakoba Beach, Jayapura City. The method used in this research is an experimental method with pigment analysis using Thin Chromatography and Visible UV Spectrophotometry. The TLC plate test shows the results of identification of the crude extract of the Gelidium corneum pigment. The first three spots are green with an Rf value of 0.24 identified as chlorophyll compounds, the second spot is blue green which is identified as chlorophyll a compound with an Rf value of 0.26 and the third spot was green and yellow identified as chlorophyll b compound with an Rf value of 0.33. The absorbance pattern or wavelength (nm) from the results of the identification of this pigment shows that there are 3 highest peaks identified as chlorophyll pigments where the absorption pattern is at a wavelength of 350-700 nm (Habone, 1987 in Doli et al, 2020).

Interdependence of fucoxanthin biosynthesis and fucoxanthin-chlorophyll a/c binding proteins in Phaeodactylum tricornutum under different light intensities

Fucoxanthin (FX), a primary carotenoid, is associated with the fucoxanthin-chlorophyll a/c binding protein (FCP) complex integrated into the thylakoid membrane (TM) which functions as a light-harvesting complex in the diatom Phaeodactylum tricornutum. Here, we aimed to elucidate the FX production regulated by different light intensities via the correlation of FX biosynthesis and apoproteins composing of FCP complex. High light (HL) accelerated P. tricornutum growth more than low light (LL). The maximum values of FX content and productivity obtained under LL (1.7 mg g−1 and 2.12 mg L−1 day−1, respectively) were substantially higher than those obtained under HL (0.54 mg g−1 and 0.79 mg L−1 day−1, respectively). Notably, proteome and photosynthetic pigment analyses revealed the enrichment of FCP antennae in the LL culture TM fractions but not the HL culture. Semi-quantification of FCP antenna protein using LC–MS/MS and RNA transcriptome analyses revealed that PtLhcf5 and PtLhcf8 played crucial roles in FCP biosynthesis under LL. P. tricornutum cultured under light transition exhibited FCP formation only in the early growth stage to meet the increased photosynthetic activity requirements under LL. Meanwhile, FCP degradation could be triggered by HL throughout the cultivation period. Therefore, FX production was highly correlated with FCP formation, and LL conditions in the early growth stage were critical for higher FX productivity.

Immediate effect of sewerage improvement on the phytoplankton and physicochemical conditions in the Urdaibai estuary (southeastern Bay of Biscay)

Anthropic nutrient enrichment has become a major environmental issue in estuaries around the world, being the effluents of wastewater treatment plants (WWTPs) one of the main causes. Phytoplankton is, together with nutrients, a useful indicator for the ecological status assessment of estuaries due to its basal position in the food chain. The present study aims to evaluate the immediate effect of the cessation of the wastewater discharges on the environmental conditions and phytoplankton community along the eutrophicated Urdaibai estuary (southeastern Bay of Biscay). Thus, a short-term comparison of the physicochemical conditions and the phytoplankton abundance and community composition (by pigment analysis and microscopy) was carried out before and after the sewerage works. Results confirmed that the cessation of wastewater discharges had an immediate effect in the estuary, mainly noticed in the inner part. The abrupt decrease of ammonium (from 72.3 to 18.2μmol/L) and phosphate (from 3.5 to 2μmol/L) concentrations led to the improvement of the water status, reaching values lower than the “good” status threshold along the whole estuary. The phytoplankton community composition also showed and immediate reaction in the surroundings of the WWTP, with the chlorophyll b becoming the dominant secondary pigment in the area after the diversion due to the immediate and rapid increase of Eutreptiella sp. However, since the sampling-period of this study did not exceed a month after the cessation, a longer study-period is necessary, including interannual studies, to test the real effect of the sanitation works in the Urdaibai estuary.

Virtual reconstruction of the painting process and original colors of a color-changed Northern Wei Dynasty mural in Cave 254 of the Mogao Grottoes

The Northern Wei Dynasty (386–534 CE) murals of Cave 254 in the Mogao Grottoes, China, have been extensively affected by pigment color changes and fading. These issues severely hinder efforts to correctly understand the value and painting process of murals from this historic period. The virtual reconstruction of the faded murals reflects the analysis results of the pigments applied during the painting process and provides a new direction for conservation and art research. However, simple virtual reconstructions may not be accurate owing to deficiencies in our understanding of the color-changed pigments and fading of image lines. In this study, multi-band imaging (MSI) was performed to obtain infrared-reflected false color, ultraviolet-reflected false color, and ultraviolet luminescence images of the mural. A portable X-ray fluorescence spectrometer, portable digital microscope, scanning electron microscope, energy dispersive X-ray spectrometer, liquid chromatography–mass spectrometer, and confocal Raman microscope were used. Non-invasive and minimally invasive analyses of local portions of different color areas were performed to identify their pigments and map the strata, and a hue–saturation–brightness palette was constructed for these pigments. Finally, the pigment analysis results were combined with the multi-band image features to determine the pigment distribution of the mural, which was then used to virtually reconstruct the original color and appearance of the faded mural under ideal conditions. This study is the first to use a virtual reconstruction based on objective analyses to simulate the original color, painting processes, and pigment stratigraphy of a mural from the Northern Wei Dynasty. A preliminary discussion of the relationship between the painting processes of the mural and color changes in its pigments was also performed. The findings of this study will provide new perspectives on the study of Northern Wei Dynasty murals.

Influence of Different Dye Substances on the Effectiveness of Bleaching and H2O2 Diffusion.

This study aimed to evaluate the influence of different dye substances on the effectiveness of bleaching and hydrogen peroxide diffusion (HO). From 300 central bovine incisors, 160 enamel/dentin disks with similar E* values were selected. The specimens were distributed according to the pigment treatment. Aiming to standardize the chromatic change provided by the different pigments, the specimens from each group remained immersed in the pigment solutions for different times (32 specimens per group): DW - distilled water (Control group); BT - black tea; CO - coffee; SD - cola-based soft drink; and RW - red wine. After pigmentation and chromatic change value analysis, only 10 specimens from each group (n=10) were selected, so the chromatic alteration of all groups was similar (ΔE=8.36±0.5). The samples were subjected to bleaching treatment and diffused peroxide was quantified in a visible ultraviolet light spectrophotometer. Two more bleaching sessions were conducted to evaluate ΔE and the Whiteness Index for Dentistry (ΔWID). Concurrently, solutions were prepared with dye agents, and the same ΔE value was obtained in the teeth (ΔE=8.49±0.5). The solutions received a standardized amount of H2O2, being analyzed by a visible ultraviolet light spectrophotometer. Data analysis comprised variance and Tukey's tests (α=0.05). Higher H2O2 diffusion was observed in pigmented groups when compared with DW (p<0.05). The CO and RW groups had the highest ΔE values (p>0.05), meaning greater difficulty in responding to treatment. In relation to ΔWID, RW bleached less than the other groups after the third bleaching session (p<0.05), resembling only the SD group (p=0.467). However, 21 days after ending the bleaching treatment, only RW and CO had the lowest values (p=0.481). Analysis of the solutions revealed that only RW was altered by the peroxide (p<0.05). In conclusion, teeth pigmented with coffee and, mainly, red wine were more resistant to bleaching treatment, although all pigmentations favored increases in transenamel and transdentinal H2O2 penetration.

PH induced stress enhances lipid accumulation in microalgae grown under mixotrophic and autotrophic condition

Production of biodiesel together with wastewater treatment and CO2 sequestration is a promising technology. The growing levels of carbon dioxide in the atmosphere increase the amount of dissolved CO2 in natural watercourses, triggering the increase in concentrations of bicarbonate and hydrogen ions while dropping those of carbonate and hydroxyl ions. The active carbon cycling in coastal areas, which can result in periodic and daily fluctuations in pH and CO2 concentrations that may surpass those anticipated for the extensive marine ecosystems, is regarded as one of the consequences of climate change. Studies were conducted to examine the effects of various pH levels on algal growth and lipid production in order to better understand how the growth of algae may be influenced in such conditions. In the present study, the influence of three different pH levels (6, 8, and 10) was studied to evaluate microalgae’s carbohydrate utilisation and lipid accumulation during the operation’s starvation phase (SP). Microalgae, in the study, were cultivated in two modes, namely mixotrophic [growth phase (GP)] and autotrophic [pH-induced (SP)] conditions. Enhancement in biomass formation, and intracellular carbohydrate accumulation were recorded during the GP operation, while noticeable lipid productivities (Total/neutral, 26.93/10.3%) were observed during SP operation at pH 8. Pigment analysis showed variations in both the procedures where higher Chl a concentration was noticed in GP, and higher Chl b was detected during SP. Nile red fluorescent staining strongly supports the existence of intracellular lipid bodies (LB). GC analysis of fatty acid methyl esters (FAME) showed the existence of a substantial amount of saturated fatty acids (SFA) compared with unsaturated fatty acids (USFA). Efficient wastewater treatment with nutrient assimilation was reported during the GP operation, demonstrating the phyco-remediation.