Dielectric Dispersion in Ga<Subscript>2</Subscript>S<Subscript>3</Subscript> Thin Films

In this work, the structural, compositional, optical, and dielectric properties of Ga₂S₃ thin films are investigated by means of X-ray diffraction, scanning electron microscopy, energy dispersion X-ray analysis, and ultraviolet—visible light spectrophotometry. The Ga₂S₃ thin films which exhibited amorphous nature in its as grown form are observed to be generally composed of 40.7 % Ga and 59.3 % S atomic content. The direct allowed transitions optical energy bandgap is found to be 2.96 eV. On the other hand, the modeling of the dielectric spectra in the frequency range of 270–1,000 THz, using the modified Drude-Lorentz model for electron-plasmon interactions revealed the electrons scattering time as 1.8 (fs), the electron bounded plasma frequency as ~0.76–0.94 (GHz) and the reduced resonant frequency as 2.20–4.60 ×10¹⁵ (Hz) in the range of 270–753 THz. The corresponding drift mobility of electrons to the terahertz oscillating incident electric field is found to be 7.91 (cm ²/Vs). The values are promising as they nominate the Ga₂S₃ thin films as effective candidates in thin-film transistor and gas sensing technologies.     

Titanium Dioxide Nanoparticles Affect the Percentage of Free Radical Scavenging,Protein Content and DNA Mismatch Repair Genes in <Emphasis Type="Italic">Zea mays</Emphasis> L. and <Emphasis Type="Italic">Triticum aestivum</Emphasis> L.

This paper identifies the potential molecular markers predicting the impact of nTiO₂ on plants and explores the new statistical correlations between the biomarkers and growth parameters. The quantitative mRNA expression of the three genes involved in DNA mismatch repair (MLH1) and cell division (PCNA1 and PCNA2) in Zea mays and Triticum aestivum seedlings were related to the growth parameters measured in response to five nTiO2 treatments. The results indicated that the higher concentrations were harmless to Z. mays but not to T. aestivum. nTiO₂ treatments increased the total protein levels in both species and significantly inhibited the percentage of DPPH radical scavenging in Z. mays compared with T. aestivum seedlings. The exposure to both 50 μg/ml and 30 μg/ml concentrations of nTiO₂ significantly induced the expression of MLH1 and PCNA1 genes in both species; however, the exposure to 30 μg/ml of nTiO₂ also significantly induced the expression of PCNA2 genes in T. aestivum. The exposure to 50, 70 and 140 μg/ml significantly inhibited the expression of PCNA2 in both species, while 70 and 140 μg/ml repressed the expression of MLH1 and PCNA1 in the seedlings of Z. mays. The induction and repression of the expression of the three genes were correlated with some growth parameters and biological indices in both species. This key finding suggests that the above genes may play a vital role in mediating plant stress response to nTiO₂ and could be used as sensitive molecular biomarkers indicative of the oxidative stress of nTiO₂ exposure.     

Photosynthetic CO<Subscript>2</Subscript> uptake in seedlings of two tropical tree species exposed to oscillating elevated concentrations of CO<Subscript>2</Subscript>

Do short-term fluctuations in CO₂ concentrations at elevated CO₂ levels affect net CO₂ uptake rates of plants? When exposed to 600 μl CO₂ l^?1, net CO₂ uptake rates in shoots or leaves of seedlings of two tropical C₃ tree species, teak (Tectona grandis L. f.) and barrigon [Pseudobombax septenatum (Jacq.) Dug.], increased by 28 and 52% respectively. In the presence of oscillations with half-cycles of 20 s, amplitude of ca. 170 μl CO₂ l^?1 and mean of 600 μl CO₂ l^?1, the stimulation in net CO₂ uptake by the two species was reduced to 19 and 36%, respectively, i.e. the CO₂ stimulation in photosynthesis associated with a change in exposure from 370 to 600 μl CO₂ l^?1 was reduced by a third in both species. Similar reductions in CO₂-stimulated net CO₂ uptake were observed in T. grandis exposed to 40-s oscillations. Rates of CO₂ efflux in the dark by whole shoots of T. grandis decreased by 4.8% upon exposure of plants grown at 370 μl CO₂ l^?1 to 600 μl CO₂ l^?1. The potential implications of the observations on CO₂ oscillations and dark respiration are discussed in the context of free-air CO₂ enrichment (FACE) systems in which short-term fluctuations of CO₂ concentration are a common feature.     

Magnetophoretic harvesting of freshwater microalgae using polypyrrole/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanocomposite and its reusability

A magnetophoretic harvesting agent, a polypyrrole/Fe₃O₄ magnetic nanocomposite, is proposed as a cost and energy efficient alternative to recover biomass of the microalgae Botryococcus braunii, Chlorella protothecoides, and Chlorella vulgaris from their culture media. The maximal recovery efficiency reached almost 99 % for B. braunii, 92.4 % for C. protothecoides, and 90.8 % for C. vulgaris. The maximum adsorption capacity (Q ₀) of the magnetic nanocomposite for B. braunii (63.49 mg dry biomass mg^?1 PPy/Fe₃O₄) was higher than that for C. protothecoides (43.91 mg dry biomass mg^?1 PPy/Fe₃O₄) and C. vulgaris (39.98 mg dry biomass mg^?1 PPy/Fe₃O₄). The highest harvesting efficiency for all the studied microalgae were at pH 10.0, and measurement of zeta-potential confirmed that the flocculation was induced by charge neutralization. This study showed that polypyrrole/Fe₃O₄ can be a promising flocculant due to its high efficacy, low dose requirements, short settling time, its integrity with cells, and with great potential for saving energy because of its recyclability.     

Bacterial metabolites from intra- and inter-species influencing thermotolerance: the case of <Emphasis Type="Italic">Bacillus cereus</Emphasis> and <Emphasis Type="Italic">Geobacillus stearothermophilus</Emphasis>

Bacterial metabolites with communicative functions could provide protection against stress conditions to members of the same species. Yet, information remains limited about protection provided by metabolites in Bacillus cereus and inter-species. This study investigated the effect of extracellular compounds derived from heat shocked (HS) and non-HS cultures of B. cereus and Geobacillus stearothermophilus on the thermotolerance of non-HS vegetative and sporulating B. cereus. Cultures of B. cereus and G. stearothermophilus were subjected to HS (42 or 65 °C respectively for 30 min) or non-HS treatments. Cells and supernatants were separated, mixed in a combined array, and then exposed to 50 °C for 60 min and viable cells determined. For spores, D values (85 and 95 °C) were evaluated after 120 h. In most cases, supernatants from HS B. cereus cultures added to non-HS B. cereus cells caused their thermotolerance to increase (D ₅₀ 12.2–51.9) when compared to supernatants from non-HS cultures (D ₅₀ 7.4–21.7). While the addition of supernatants from HS and non-HS G. stearothermophilus cultures caused the thermotolerance of non-HS cells from B. cereus to decrease initially (D ₅₀ 3.7–7.1), a subsequent increase was detected in most cases (D ₅₀ 18–97.7). In most cases, supernatants from sporulating G. stearothermophilus added to sporulating cells of B. cereus caused the thermotolerance of B. cereus 4810 spores to decline, whereas that of B. cereus 14579 increased. This study clearly shows that metabolites in supernatants from either the same or different species (such as G. stearothermophilus) influence the thermotolerance of B. cereus.     

P2Y<Subscript>2</Subscript> and P2Y<Subscript>6</Subscript> receptor activation elicits intracellular calcium responses in human adipose-derived mesenchymal stromal cells

Adipose tissue contains self-renewing multipotent cells termed mesenchymal stromal cells. In situ, these cells serve to expand adipose tissue by adipogenesis, but their multipotency has gained interest for use in tissue regeneration. Little is known regarding the repertoire of receptors expressed by adipose-derived mesenchymal stromal cells (AD-MSCs). The purpose of this study was to undertake a comprehensive analysis of purinergic receptor expression. Mesenchymal stromal cells were isolated from human subcutaneous adipose tissue and confirmed by flow cytometry. The expression profile of purinergic receptors was determined by quantitative real-time PCR and immunocytochemistry. The molecular basis for adenine and uracil nucleotide-evoked intracellular calcium responses was determined using Fura-2 measurements. All the known subtypes of P2X and P2Y receptors, excluding P2X2, P2X3 and P2Y₁₂ receptors, were detected at the mRNA and protein level. ATP, ADP and UTP elicited concentration-dependent calcium responses in mesenchymal cells (N?=?7–9 donors), with a potency ranking ADP (EC₅₀ 1.3 ± 1.0 μM)?>?ATP (EC₅₀ 2.2 ± 1.1 μM)?=?UTP (3.2 ± 2.8 μM). Cells were unresponsive to UDP (<?30 μM) and UDP-glucose (<?30 μM). ATP responses were attenuated by selective P2Y₂ receptor antagonism (AR-C118925XX; IC₅₀ 1.1 ± 0.8 μM, 73.0?±?8.5% max inhibition; N?=?7 donors), and UTP responses were abolished. ADP responses were attenuated by the selective P2Y₆ receptor antagonist, MRS2587 (IC₅₀ 437 ± 133nM, 81.0?±?8.4% max inhibition; N?=?6 donors). These data demonstrate that adenine and uracil nucleotides elicit intracellular calcium responses in human AD-MSCs with a predominant role for P2Y₂ and P2Y₆ receptor activation. This study furthers understanding about how human adipose-derived mesenchymal stromal cells can respond to external signalling cues.     

Impact of elevated CO<Subscript>2</Subscript> in <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> rooted stem cuttings inoculated with <Emphasis Type="Italic">Frankia</Emphasis>

Impact of different levels of elevated CO ₂ on the activity of Frankia (Nitrogen-fixing actinomycete) in Casuarina equisetifolia rooted stem cuttings has been studied to understand the relationship between C. equisetifolia, Frankia and CO₂. The stem cuttings of C. equietifolia were collected and treated with 2000 ppm of Indole Butyric Acid (IBA) for rooting. Thus vegetative propagated rooted stem cuttings of C. equisetifolia were inoculated with Frankia and placed in the Open top chambers (OTC) with elevated CO₂ facilities. These planting stocks were maintained in the OTC for 12 months under different levels of elevated CO₂ (ambient control, 600 ppm, 900 ppm). After 12 months, the nodule numbers, bio mass, growth, and photosynthesis of C. equisetifolia rooted stem cuttings inoculated with Frankia were improved under 600 ppm of CO₂. The rooted stem cuttings of C. equisetifolia inoculated with Frankia showed a higher number of nodules under 900 ppm of CO₂ and cuttings without Frankia inoculation exhibited poor growth. Tissue Nitrogen (N) content was also higher under 900 ppm of CO₂ than ambient control and 600 ppm levels. The photosynthetic rate was higher (17.8 μ mol CO₂ m^?2 s^?1) in 900 ppm of CO₂ than in 600 ppm (13.2 μ mol CO₂ m^?2 s^?1) and ambient control (8.3 μ mol CO₂ m^?2 s^?1). This study showed that Frankia can improve growth, N fixation and photosynthesis of C. equietifolia rooted stem cuttings under extreme elevated CO₂ level conditions (900 ppm).     

Phenotypic and biochemical alterations in relation to <Emphasis Type="Italic">MT2</Emphasis> gene expression in <Emphasis Type="Italic">Plantago ovata</Emphasis> Forsk under zinc stress

Plantago ovata Forsk is an annual herb with immense medicinal importance, the seed and husk of which is used in the treatment of chronic constipation, irritable bowel syndrome, diarrhea since ancient times. Zinc, an essential metal, is required by plants as they form important components of zinc finger proteins and also aid in synthesis of photosynthetic pigments such as chlorophyll. However, in excess amount Zn causes chlorosis of leaf and shoot tissues and generate reactive oxygen species. The present study is aimed at investigating the changes in expression levels of MT2 gene in Plantago ovata under zinc stress. Data show up to 1.66 fold increase in expression of PoMT2 in 1000 µM ZnSO₄·7H₂O treated sample. Our study also describes alteration of MT2 gene expressions in Plantago ovata as observed through Real time PCR (qPCR) done by \(2^{{ - \Delta \Delta}} C_T\) method. In this study we have observed an upregulation (or induction) in the PoMT2 gene expression level in 500 and 800 µM ZnSO₄·7H₂O treated samples but found saturation on further increasing the dose to 1000 µM of ZnSO₄·7H₂O. Determination of the phenotypic and biochemical changes in Plantago ovata due to exposure to zinc stress of concentrations 500, 800 and 1000 µM revealed oxidative stress. The enhanced expression of MT2 gene in Plantago ovata has a correlation with the increased total antioxidant activity and increased DPPH radical scavenging activity.     

Interacting effects of elevated atmospheric CO<Subscript>2</Subscript> and hydrology on the growth and carbon sequestration of <Emphasis Type="Italic">Sphagnum</Emphasis> moss

Peatlands are a critical carbon store comprising 30% of the Earth’s terrestrial soil carbon. Sphagnum mosses comprise up to 90% of peat in the northern hemisphere but impacts of climate change on Sphagnum mosses are poorly understood, limiting development of sustainable peatland management and restoration. This study investigates the effects of elevated atmospheric CO₂ (eCO₂) (800 ppm) and hydrology on the growth of Sphagnum fallax, Sphagnum capillifolium and Sphagnum papillosum and greenhouse gas fluxes from moss–peat mesocosms. Elevated CO₂ levels increased Sphagnum height and dry weight but the magnitude of the response differed among species. The most responsive species, S. fallax, yielded the most biomass compared to S. papillosum and S. capillifolium. Water levels and the CO₂ treatment were found to interact, with the highest water level (1 cm below the surface) seeing the largest increase in dry weight under eCO₂ compared to ambient (400 ppm) concentrations. Initially, CO₂ flux rates were similar between CO₂ treatments. After week 9 there was a consistent three-fold increase of the CO₂ sink strength under eCO₂. At the end of the experiment, S. papillosum and S. fallax were greater sinks of CO₂ than S. capillifolium and the ? 7 cm water level treatment showed the strongest CO₂ sink strength. The mesocosms were net sources of CH₄ but the source strength varied with species, specifically S. fallax produced more CH₄ than S. papillosum and S. capillifolium. Our findings demonstrate the importance of species selection on the outcomes of peatland restoration with regards to Sphagnum’s growth and GHG exchange.     

Exploiting mixtures of H<Subscript>2</Subscript>, CO<Subscript>2</Subscript>, and O<Subscript>2</Subscript> for improved production of methacrylate precursor 2-hydroxyisobutyric acid by engineered <Emphasis Type="Italic">Cupriavidus necator</Emphasis> strains

Current manufacturing of most bulk chemicals through petrochemical routes considerably contributes to common concerns over the depletion of fossil carbon sources and greenhouse gas emissions. Sustainable future production of commodities thus requires the shift to renewable feedstocks in combination with established or newly developed synthesis routes. In this study, the potential of Cupriavidus necator H16 for autotrophic synthesis of the building block chemical 2-hydroxyisobutyric acid (2-HIBA) is evaluated. A novel biosynthetic pathway was implemented by heterologous expression of the 2-hydroxyisobutyryl-coenzyme A (2-HIB-CoA) mutase from Aquincola tertiaricarbonis L108, relying on a main intermediate of strain H16’s C4 overflow metabolism, 3-hydroxybutyryl-CoA. The intention was to direct the latter to 2-HIBA instead or in addition to poly-3-hydroxybutyrate (PHB). Autotrophic growth and 2-HIBA (respectively, PHB) synthesis of wild-type and PHB-negative mutant strains were investigated producing maximum 2-HIBA titers of 3.2 g L^?1 and maximum specific 2-HIBA synthesis rates (q _2-HIBA) of about 16 and 175 μmol g^?1 h^?1, respectively. The obtained specific productivity was the highest reported to date for mutase-dependent 2-HIBA synthesis from heterotrophic and autotrophic substrates. Furthermore, expression of a G protein chaperone (MeaH) in addition to the 2-HIB-CoA mutase subunits yielded improved productivity. Analyzing the inhibition of growth and product synthesis due to substrate availability and product accumulation revealed a strong influence of 2-HIBA, when cells were cultivated at high titers. Nevertheless, the presented results imply that at the time the autotrophic synthesis route is superior to thus far established heterotrophic routes for production of 2-HIBA with C. necator.     

Aflatoxin B<Subscript>1</Subscript> levels in groundnut products from local markets in Zambia

In Zambia, groundnut products (milled groundnut powder, groundnut kernels) are mostly sold in under-regulated markets. Coupled with the lack of quality enforcement in such markets, consumers may be at risk to aflatoxin exposure. However, the level of aflatoxin contamination in these products is not known. Compared to groundnut kernels, milled groundnut powder obscures visual indicators of aflatoxin contamination in groundnuts such as moldiness, discoloration, insect damage or kernel damage. A survey was therefore conducted from 2012 to 2014, to estimate and compare aflatoxin levels in these products (n = 202), purchased from markets in important groundnut growing districts and in urban areas. Samples of whole groundnut kernels (n = 163) and milled groundnut powder (n = 39) were analysed for aflatoxin B₁ (AFB₁) by competitive enzyme-linked immunosorbent assay (cELISA). Results showed substantial AFB₁ contamination levels in both types of groundnut products with maximum AFB₁ levels of 11,100 μg/kg (groundnut kernels) and 3000 μg/kg (milled groundnut powder). However, paired t test analysis showed that AFB₁ contamination levels in milled groundnut powder were not always significantly higher (P > 0.05) than those in groundnut kernels. Even for products from the same vendor, AFB₁ levels were not consistently higher in milled groundnut powder than in whole groundnut kernels. This suggests that vendors do not systematically sort out whole groundnut kernels of visually poor quality for milling. However, the overall contamination levels of groundnut products with AFB₁ were found to be alarmingly high in all years and locations. Therefore, solutions are needed to reduce aflatoxin levels in such under-regulated markets.     

Serum Trace Elements and Electrolytes Are Associated with Fasting Plasma Glucose and HbA<Subscript>1c</Subscript> in Postmenopausal Women with Type 2 Diabetes Mellitus

The primary aim of the research was to assess the level of trace elements and electrolytes in serum of postmenopausal diabetic women. Sixty-four postmenopausal women with type 2 diabetes mellitus (DM2) and 64 age- and body mass index-matched controls were examined. Serum trace elements were assessed using inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS). Fasting plasma glucose (FPG) and glycated hemoglobin (HbA_1c) levels were evaluated using Randox kits. The obtained data demonstrate that DM2 patients were characterized by 42 and 34 % higher FPG and HbA_1c levels, respectively (p < 0.001). The level of Cu and Se in diabetic postmenopausal women was increased by 10 and 15 % in comparison to the respective control values (p = 0.002 and <0.001). Serum Mn, Zn, and Ni concentrations were lower than the control ones by 32 % (p = 0.003), 8 % (p = 0.003), and 23 % (p = 0.046), respectively. FPG and HbA_1c levels directly correlated with serum Se (p < 0.001) and Cu (p = 0.014 and p = 0.028) concentrations and inversely related to Zn (p < 0.001) and Tl (p = 0.023 and p = 0.029) levels. Multiple regression analysis demonstrated a significant association between serum Zn and Se and FPG and HbA_1c levels. It is proposed that Zn and Se play an important role in DM2 pathogenesis. Further studies are required to assess the intimate mechanisms of the observed differences.     

Interactive effects of soil salinity and boron on growth,mineral composition and CO<Subscript>2</Subscript> assimilation of pistachio seedlings

Pistachio is a tree of the arid and semi-arid regions where salinity and boron (B) toxicity can be major environmental stresses. In this study, individual and combined effects of different concentrations of NaCl (0, 800, 1600, 2400 and 3200 mg kg^?1 soil) and B (0, 2.5, 5.0, 10.0 and 20.0 mg kg^?1 soil) were studied on growth, gas-exchange and mineral composition of pistachio seedlings for a duration of 120 days. Excess amounts of salinity (> 1600 mg NaCl kg^?1 soil) and B (20.0 mg kg^?1 soil) significantly reduced the plant growth and CO₂ assimilation, which was associated with accumulation of Na, Cl and B in leaves. There was also a decline in cell membrane stability index (MSI). Reduced stomatal conductance (g _s) was the primary cause of inhibition of photosynthesis rate (P _N) under mild to moderate salinity. However, under severe salt stress and B toxicity, non-stomatal effects contributed to the inhibition of CO₂ assimilation in addition to the decline in g _s value. Application of 5.0–10.0 mg B kg^?1 soil significantly improved the plant growth and P _N and also recovered the MSI as countermeasures against salt stress. These observations were related to the role of B in cell membrane structure and functioning which reduced the concentration of toxic ions in the leaves. However, cell membrane damages and chlorophyll loss in plants affected by salt were observed to be exacerbated when excess amounts of B were present. In conclusion, the results revealed that optimizing the B nutrition can improve the performance of pistachio seedlings under salt stress, and NaCl also showed a mitigating effect on B toxicity if its concentration in the soil is kept under the plant salt tolerance threshold.     

Investigation of feeding behaviour in <Emphasis Type="Italic">C. elegans</Emphasis> reveals distinct pharmacological and antibacterial effects of nicotine

Caenorhabditis elegans is an informative model to study the neural basis of feeding. A useful paradigm is one in which adult nematodes feed on a bacterial lawn which has been pre-loaded with pharmacological agents and the effect on pharyngeal pumping rate scored. A crucial aspect of this assay is the availability of good quality bacteria to stimulate pumping to maximal levels. A potential confound is the possibility that the pharmacological agent impacts bacterial viability and indirectly influences feeding rate. Here, the actions of nicotine on pharyngeal pumping of C. elegans and on the Escherichia coli bacterial food source were investigated. Nicotine caused an immediate and concentration-dependent inhibition of C. elegans pharyngeal pumping, IC₅₀ 4 mM (95% CI?=?3.4 mM to 4.8 mM). At concentrations between 5 and 25 mM, nicotine also affected the growth and viability of E. coli lawns. To test whether this food depletion by nicotine caused the reduced pumping, we modified the experimental paradigm. We investigated pharyngeal pumping stimulated by 10 mM 5-HT, a food ‘mimic’, before testing if nicotine still inhibited this behaviour. The IC₅₀ for nicotine in these assays was 2.9 mM (95% CI?=?3.1 mM to 5.1 mM) indicating the depletion of food lawn does not underpin the potency of nicotine at inhibiting feeding. These studies show that the inhibitory effect of nicotine on C. elegans pharyngeal pumping is mediated by a direct effect rather than by its poorly reported bactericidal actions.     

Recombinant Production and Antimicrobial Assessment of <Emphasis Type="Italic">Beta</Emphasis> Casein- IbAMP<Subscript>4</Subscript> as a Novel Antimicrobial Polymeric Protein and its Synergistic Effects with Thymol

There is a growing research interest on products with antimicrobial activity. Antimicrobial polymers are one of the most surefire procedures to combat microbes. In the present study, the ability of Βeta-casein- one of the milk major self assembly proteins with high polymeric film production capability—as a fusion partner of Ib-AMP₄ antimicrobial peptide was investigated. Also, the antimicrobial activities of Βeta-casein- IbAMP₄ fusion protein antimicrobial against common food pathogens were assessed. The pET21a-BCN-Ib-AMP ₄ construct was transformed to Escherichia coli BL21 (DE3), and protein expression was induced under optimized conditions. Purified protein obtained from nickel affinity chromatography was refolded under optimized dialysis circumstances and concentrated to 1600 µg mL^?1 fusion protein by ultrafiltration. 5 μg mL^?1 H₂O₂ was applied for accelerating the formation of two necessary disulfide bonds. Antimicrobial assays were performed against E. coli, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, Aspergillus flavus and Candida albicans. Results of antimicrobial tests confirmed the efficiency of BCN-IbAMP₄ against all tested microorganisms. Overall, the combination of thymol plus BCN-IbAMP₄ increased their antimicrobial activities. MIC, MBC, MFC, FICI and FBCI values showed strong synergistic activity between the two examined compounds. Time kill and growth kinetic studies indicated significant reduction of cell viability during first period of exposure to BCN-IbAMP₄ and thymol combination.     

Over-Expression of <Emphasis Type="Italic">PmHSP17.9</Emphasis> in Transgenic <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> Confers Thermotolerance

Small heat shock proteins (sHSPs) have been shown to be involved in stress tolerance. However, their functions in Prunus mume under heat treatment are poorly characterized. To improve our understanding of sHSPs, we cloned a sHSP gene, PmHSP17.9, from P. mume. Sequence alignment and phylogenetic analysis indicated that PmHSP17.9 was a member of plant cytosolic class III sHSPs. Besides heat stress, PmHSP17.9 was also upregulated by salt, dehydration, oxidative stresses and ABA treatment. Leaves of transgenic Arabidopsis thaliana that ectopically express PmHSP17.9 accumulated less O₂ ^? and H₂O₂ compared with wild type (WT) after 42 °C treatment for 6 h. Over-expression of PmHSP17.9 in transgenic Arabidopsis enhanced seedling thermotolerance by decreased relative electrolyte leakage and MDA content under heat stress treatment when compared to WT plants. In addition, the induced expression of HSP101, HSFA2, and delta 1-pyrroline-5-carboxylate synthase (P5CS) under heat stress was more pronounced in transgenic plants than in WT plants. These results support the positive role of PmHSP17.9 in response to heat stress treatment.