Satellite observations for regional air quality assessment rely on comprehensive spatial coverage, and daily monitoring with reliable, cloud-free data quality. We investigated spatiotemporal variation and data quality of two global satellite Aerosol Optical Depth (AOD) products derived from MODIS and VIIRS imagery. AOD is considered an essential atmospheric parameter strongly related to ground Particulate Matter (PM) in Southeast Asia (SEA). We analyze seasonal variation, urban/rural area influence, and biomass burning effects on atmospheric pollution. Validation indicated a strong relationship between AERONET ground AOD and both MODIS AOD (R2 = 0.81) and VIIRS AOD (R2 = 0.68). The monthly variation of satellite AOD and AERONET AOD reflects two seasonal trends of air quality separately for mainland countries including Myanmar, Laos, Cambodia, Thailand, Vietnam, and Taiwan, Hong Kong, and for maritime countries consisting of Indonesia, Philippines, Malaysia, Brunei, Singapore, and Timor Leste. The mainland SEA has a pattern of monthly AOD variation in which AODs peak in March/April, decreasing during wet season from May-September, and increasing to the second peak in October. However, in maritime SEA, AOD concentration peaks in October. The three countries with the highest annual satellite AODs are Singapore, Hong Kong, and Vietnam. High urban population proportions in Singapore (40.7%) and Hong Kong (21.6%) were associated with high AOD concentrations as expected. AOD values in SEA urban areas were a factor of 1.4 higher than in rural areas, with respective averages of 0.477 and 0.336. The AOD values varied proportionately to the frequency of biomass burning in which both active fires and AOD peak in March/April and September/October. Peak AOD in September/October in some countries could be related to pollutant transport of Indonesia forest fires. This study analyzed satellite aerosol product quality in relation to AERONET in SEA countries and highlighted framework of air quality assessment over a large, complicated region.
Green microalga Ankistrodesmus convolutus Corda is a fast growing alga which produces appreciable amount of carotenoids and polyunsaturated fatty acids. To our knowledge, this is the first report on the construction of cDNA library and preliminary analysis of ESTs for this species. The titers of the primary and amplified cDNA libraries were 1.1×10(6) and 6.0×10(9) pfu/ml respectively. The percentage of recombinants was 97% in the primary library and a total of 337 out of 415 original cDNA clones selected randomly contained inserts ranging from 600 to 1,500 bps. A total of 201 individual ESTs with sizes ranging from 390 to 1,038 bps were then analyzed and the BLASTX score revealed that 35.8% of the sequences were classified as strong match, 38.3% as nominal and 25.9% as weak match. Among the ESTs with known putative function, 21.4% of them were found to be related to gene expression, 14.4% ESTs to photosynthesis, 10.9% ESTs to metabolism, 5.5% ESTs to miscellaneous, 2.0% to stress response, and the remaining 45.8% were classified as novel genes. Analysis of ESTs described in this paper can be an effective approach to isolate and characterize new genes from A. convolutus and thus the sequences obtained represented a significant contribution to the extensive database of sequences from green microalgae.
An initial study on gene cloning and characterization of unicellular green microalga Ankistrodesmus convolutus was carried out to isolate and characterize the full-length cDNA of ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (RbcS) as a first step towards elucidating the structure of A. convolutus RbcS gene. The full-length of A. convolutus RbcS cDNA (AcRbcS) contained 28 bp of 5' untranslated region (UTR), 225 bp of 3' non-coding region, and an open reading frame of 165 amino acids consisting of a chloroplast transit peptide with 24 amino acids and a mature protein of 141 amino acids. The amino acid sequence has high identity to those of other green algae RbcS genes. The AcRbcS contained a few conserved domains including protein kinase C phosphorylation site, tyrosine kinase phosphorylation site and N-myristoylation sites. The AcRbcS was successfully expressed in Escherichia coli and a ~21 kDa of anticipated protein band was observed on SDS-PAGE. From the phylogenetic analysis of RbcS protein sequences, it was found that the RbcS of A. convolutus has closer genetic relationship with green microalgae species compared to those of green seaweed and green macroalgae species. Southern hybridization analysis revealed that the AcRbcS is a member of a small multigene family comprising of two to six members in A. convolutus genome. Under different illumination conditions, RT-PCR analysis showed that AcRbcS transcription was reduced in the dark, and drastically recovered in the light condition. Results presented in this paper established a good foundation for further study on the photosynthetic process of A. convolutus and other green algae species where little information is known on Rubisco small subunit.
The rapid and effective method for the isolation of RNA from green microalga Ankistrodesmus convolutus based on homogenization in a simple CTAB buffer and selective precipitation of RNA with lithium chloride is developed. This procedure avoids the use of toxic chaotropic agents and phenol while high concentration of dithiothreitol is used to inhibit RNase activity and prevent oxidative cross-linking of nucleic acids by phenolics. The extraction procedure was able to produce high quality and intact RNA from A. convolutus. The yield of total RNA was 0.69-0.73 mg/g of fresh weight, with A(260)/A(280) ratio of 1.79-1.86. The obtained RNA was of sufficient quality and suitable for downstream application such as RT-PCR and cDNA library construction. The procedure may also have wider applicability for total RNA isolation from other green microalgae species.
Environmental degradation is significantly studied both in the past and the current literature; however, steps towards reducing the environmental pollution in carbon emission and haze pollution like PM2.5 are not under rational attention. This study tries to cover this gap while considering the carbon emission and PM2.5 through observing the role of renewable energy, non-renewable energy, environmental taxes, and ecological innovation for the top Asian economies from 1990 to 2017. For analysis purposes, this research considers cross-sectional dependence analysis, unit root test with and without structural break (Pesaran, 2007), slope heterogeneity analysis, Westerlund and Edgerton (2008) panel cointegration analysis, Banerjee and Carrion-i-Silvestre (2017) cointegration analysis, long-short run CS-ARDL results, as well as AMG and CCEMG for robustness check. The empirical evidence in both the short- and long-run has confirmed the negative and significant effect of renewable energy sources, ecological innovation, and environmental taxes on carbon emissions and PM2.5. Whereas, non-renewable energy sources are causing environmental degradation in the targeted economies. Finally, various policy implications related to carbon emission and haze pollution like PM2.5 are also provided to control their harmful effect on the natural environment.
Isolation of promoter sequences from known gene sequences is a tedious task in genome-related research. An efficient method of obtaining the promoter sequences is necessary in order to successfully use targeted promoters for genetic manipulations. Here, efficiency and usefulness of two PCR-based methods, namely: ligation-mediated PCR and thermal asymmetric interlaced (TAIL) PCR, for isolation of promoter sequences of the ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (RbcS) gene from green microalgae Ankistrodesmus convolutus (A. convolutus) were evaluated. The results showed that the amplification efficiency of TAIL-PCR was higher than that of the ligation-mediated PCR method, i.e. the amplified promoter fragments of 1.2 and 0.8 kb in length or promoter sequences of 813 and 606 bp (after eliminating the unreadable sequences). The use of TAIL-PCR described here presents a low cost and efficient strategy for the isolation of promoter sequences of known genes, especially in GC-rich regions, and species with little or no available genome information such as A. convolutus.
While insight into consumer brand engagement, experience, and identification is rapidly developing, little remains known regarding the association of these, and related, concepts, as therefore explored in this article. Drawing on social identity theory and service-dominant-logic, this study develops and tests a model that explores the effect of customers' brand credibility, -value congruence, and -experience on their brand identification, and its subsequent effect on their brand advocacy, -attachment, and -loyalty. We also examine the potentially moderating role of consumers' engagement in affecting these relationships. To explore these issues, we collected tourist-based survey data. To analyze the data, we used confirmatory factor analysis, followed by structural equation modeling. The findings reveal that brand value congruence, credibility, and experience exercise significant positive effects on customers' brand identification, which, in turn, impact their brand advocacy, attachment, and loyalty. Further, brand engagement is shown to moderate the association of these factors. We conclude by outlining key theoretical/practical implications that arise from this research.
The availability of highly active homologous promoters is critical in the development of a transformation system and improvement of the transformation efficiency. To facilitate transformation of green microalga Ankistrodesmus convolutus which is considered as a potential candidate for many biotechnological applications, a highly-expressed native promoter sequence of ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (AcRbcS) has been used to drive the expression of β-glucuronidase (gusA) gene in this microalga. Besides the determination of the transcription start site by 5'-RACE, sequence analysis revealed that AcRbcS promoter contained consensus TATA-box and several putative cis-acting elements, including some representative light-regulatory elements (e.g., G-box, Sp1 motif and SORLIP2), which confer light responsiveness in plants, and several potential conserved motifs (e.g., CAGAC-motif, YCCYTGG-motifs and CACCACA-motif), which may be involved in light responsiveness of RbcS gene in green microalgae. Using AcRbcS promoter::gusA translational fusion, it was demonstrated that this promoter could function as a light-regulated promoter in transgenic A. convolutus, which suggested that the isolated AcRbcS promoter was a full and active promoter sequence that contained all cis-elements required for developmental and light-mediated control of gene expression, and this promoter can be used to drive the expression of heterologous genes in A. convolutus. This achievement therefore advances the development of A. convolutus as an alternative expression system for the production of recombinant proteins. This is the first report on development of gene manipulation system for unicellular green alga A. convolutus.
The low-cost and easy-to-use nature of rapidly developed PM2.5 sensors provide an opportunity to bring breakthroughs in PM2.5 research to resource-limited countries in Southeast Asia (SEA). This review provides an evaluation of the currently available literature and identifies research priorities in applying low-cost sensors (LCS) in PM2.5 environmental and health research in SEA. The research priority is an outcome of a series of participatory workshops under the umbrella of the International Global Atmospheric Chemistry Project-Monsoon Asia and Oceania Networking Group (IGAC-MANGO). A literature review and research prioritization are conducted with a transdisciplinary perspective of providing useful scientific evidence in assisting authorities in formulating targeted strategies to reduce severe PM2.5 pollution and health risks in this region. The PM2.5 research gaps that could be filled by LCS application are identified in five categories: source evaluation, especially for the distinctive sources in the SEA countries; hot spot investigation; peak exposure assessment; exposure-health evaluation on acute health impacts; and short-term standards. The affordability of LCS, methodology transferability, international collaboration, and stakeholder engagement are keys to success in such transdisciplinary PM2.5 research. Unique contributions to the international science community and challenges with LCS application in PM2.5 research in SEA are also discussed.