Saline Alkaline Research Articles

Cytotoxicity study and influence of SBA-15 surface polarity and pH on adsorption and release properties of anticancer agent pemetrexed.

Mesoporous material SBA-15 was functionalized with different polar and nonpolar groups: 3-aminopropyl, (SBA-15-NH2), 3-isocyanatopropyl (SBA-15-NCO), 3-mercaptopropyl (SBA-15-SH), methyl (SBA-15-CH3) and phenyl (SBA-15-Ph). The resulting surface grafted materials were investigated as matrices for controlled drug delivery. Anticancer agent, pemetrexed (disodium pemetrexed heptahydrate) was selected as a model drug and loaded in the unmodified and functionalized SBA-15 materials. Materials were characterized by elemental analysis, infrared spectroscopy, transmission electron microscopy, nitrogen adsorption/desorption analysis, small angle X-ray scattering, powder X-ray diffraction, solid state NMR spectroscopy and thermogravimetry. It was shown that surface modification has an impact on both encapsulated drug amount and release properties. Release experiments were performed into two media with different pH: simulated body fluid (pH = 7.4) and simulated gastric fluid (pH = 2). In general, the effect of pH was reflected by the lower release of pemetrexed under acidic conditions (pH = 2) compared to slightly alkaline saline environment (pH = 7.4). The release rate of pemetrexed from propylamine-, propylisocyanate- and phenyl-modified SBA-15 was found to be effectively controlled by intermolecular interactions as compared to that from pure SBA-15, SBA-15-SH, and SBA-15-CH3, that evidenced a steady and similar release. The highest release was observed for methyl-functionalized material whose hydrophobic surface accelerates the pemetrexed release. The data obtained from release studies were fitted using various kinetic models to determine the pemetrexed release mechanism and its release rate. The best correlations were found for Korsmeyer-Peppas and Higuchi models. Moreover, the theoretical three-parameter model for drug release kinetic was applied to calculate the strength of drug-support interactions. The in vitro cell study was performed on SKBR3 cancer cells and obtained results demonstrated that the modification of the mesoporous silica material by grafted polar/nonpolar groups may significantly affect the compatibility of this material with cells, drug release from this material and subsequent biological activity of PEM.

Calcium-Enriched Animal Manure Alleviates the Adverse Effects of Salt Stress on Growth, Physiology and Nutrients Homeostasis of Zea mays L.

Soil salinity and sodicity are among the main problems for optimum crop production in areas where rainfall is not enough for leaching of salts out of the rooting zone. Application of organic and Ca-based amendments have the potential to increase crop yield and productivity under saline–alkaline soil environments. Based on this hypothesis, the present study was conducted to evaluate the potential of compost, Ca-based fertilizer industry waste (Ca-FW), and Ca-fortified compost (Ca-FC) to increase growth and yield of maize under saline–sodic soil conditions. Saline–sodic soil conditions with electrical conductivity (EC) levels (1.6, 5, and 10 dS m−1) and sodium adsorption ratio (SAR) = 15, were developed by spiking soil with a solution containing NaCl, Na2SO4, MgSO4, and CaCl2. Results showed that soil salinity and sodicity significantly reduced plant growth, yield, physiological, and nutrient uptake parameters. However, the application of Ca-FC caused a remarkable increase in the studied parameters of maize at EC levels of 1.6, 5, and 10 dS m−1 as compared to the control. In addition, Ca-FC caused the maximum decrease in Na+/K+ ratio in shoot up to 85.1%, 71.79%, and 70.37% at EC levels of 1.6, 5, and 10 dS m−1, respectively as compared to the control treatment. Moreover, nutrient uptake (NPK) was also significantly increased with the application of Ca-FC under normal as well as saline–sodic soil conditions. It is thus inferred that the application of Ca-FC could be an effective amendment to enhance growth, yield, physiology, and nutrient uptake in maize under saline–sodic soil conditions constituting the novelty of this work.

Corrosion of stainless steels in acidic, neutral and alkaline saline media: Electrochemical and microscopic analysis

This study presents how SS304 and SS316 corrode in saline media, including in the presence of acid and alkali, through an electrochemical and microscopic analysis. SS304 and SS316 samples were studied for their corrosion resistance in 1M NaCl, and in the presence of either 1M HCl or 1M NaOH. Potentiodynamic polarization studies were carried out to determine the corrosion potentials and currents. From the anodic polarization, regions corresponding to corrosion, passivation and transpassivation were identified. Samples were corroded at different anodic potentials corresponding to the different regimes and were analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). In 1M NaCl medium, SS304 exhibits pitting and passivation whereas SS316 does not. Transpassivation occurs through intergranular corrosion that connects the different pits. Making the medium acidic results in much higher corrosion rates for both SS304 and SS316, but the corroded surfaces bear vastly different structures. SS304 surface forms deep pits with large intergranular cracks resembling chimney stacks. However, SS316 surfaces show dendritic morphologies of deposited corrosion products, further evidenced by a higher O/Fe ratio in EDX measurements. In alkaline media, SS304 shows evidence of pits on whose edges corrosion products are deposited while no significant pitting is seen with SS316.

Recovery of Chromium(VI) Oxyanions from Aqueous Solution Using Cu(OH)2 and CuO Embedded Chitosan Adsorbents

Owing to its availability, low cost and strong reducibility capacity, chitosan can be widely used for Cr(VI) recovery, in this study the removal of Cr(VI) from aqueous solution was investigated using composite adsorbents derived from chitosan (obtained from shrimp peels) and Cu(OH)2 or CuO (prepared by alkaline precipitation of Cu(II) ions) to manufacture ChiCu(OH)2 and ChiCuO, respectively. The adsorbents were characterized by using SEM, BET surface area and zeta potential measurements. Adsorption uptake was highly dependent on pH, temperature, Cr(VI) concentration and sorbent mass: The optimum pH for Cr(VI) removal being close to 4. The adsorption isotherm can be described by Langmuir adsorption isotherm while the uptake kinetics was highly fitted with the pseudo-second order rate equation. The effect of temperature was also evaluated, verifying the endothermic nature of the adsorption process. Chromium desorption was performed using alkaline saline solution (20 g L−1 NaCl with the pH set to 12 with NaOH). The recycling of the sorbent was tested, maintaining a removal efficiency and a metal recovery over 90% for three successive adsorption/desorption cycles. The results showed that, the fabricated nanocomposites are promising adsorbents for Cr(VI) from aqueous solution.

Phylogenetic and morphological diversity of culturable cyanobacteria from Lake Magadi in Kenya

Lake Magadi is an alkaline saline Lake in Kenya, which lies on the Great Eastern Rift valley. Although the lake is characterized by extremes of salt, pH and temperature, it supports diverse groups of cyanobacteria. In this study, we used different media to isolate novel groups of cyanobacteria. We recovered 11 isolates affiliated to the orders Chroococcales, Oscillatoriales, Pleurocapsales and Nostocales. Isolates affiliated to Chroococcidiopsis species had similarity values below 90% to currently characterized taxa indicating that these could be completely new phylotypes. This taxon has not been isolated before from the soda lake indicating the power of molecular techniques in identifying novel cyanobacterial taxa. Only two of the recovered isolates had 99% similarity to known organisms. Previous studies have mainly relied on microscopic examination and identification, which can lead to misidentification and subsequent assignment of an organism to the wrong taxon. The recovered isolates are a useful resource of more studies on taxonomy and secondary metabolite production.

Spatial distribution of soil salinity and potential implications for soil management in the Manas River watershed, China

AbstractUnderstanding the watershed‐scale spatial distribution of soil salinity and its compositions is important for soil management. Here, we present the first study on the Manas River watershed in northwest China. In this study, we took soil samples in upper 20 cm of soil from 186 locations across the watershed and measured total salt concentration (TSC), salt ion composition and soil particle size distribution (PSD). We found that on average topsoil TSC tended to increase, from 3.55 g kg−1 in upstream regions to 19.40 g kg−1 in downstream regions. The stoichiometric analysis showed that the equivalence ratio of soil Cl‐ to SO42− increased from 0.53 in upstream regions to 2.12 in midstream regions, and further to 3.76 in downstream regions; thus, the soil types were classified into chloride–sulfate, sulfate–chloride and chloride soils types, respectively. Additionally, proportions of small (<2 μm in diameter) and large (>2,000 μm) soil particles increased, while that of medium sizes (2–50 μm) decreased from upstream to downstream, with an increasing coefficient of variance (CV) in PSD. Taken together, watershed‐scale topsoil salinity may be horizontally characterized by increased TSC and Na+ & Cl− proportions, greater equivalence ratio of Cl− vs. SO42− and more balanced distribution of PSD along with surface water flow. Results demonstrated that soil salinity and its ions compositions showed a great variation across the watershed scale, suggesting that soil management may consider the spatial heterogeneity of saline–alkaline soil types, and our results provided scientific guidance for local soil management and restoration.

Bacillus lacisalsi sp. nov., a moderately haloalkaliphilic bacterium isolated from a saline-alkaline lake.

An alkaliphilic and moderately halophilic strain, designated YSP-3T, characterised by optimal growth at pH 9.0 and at 8.0% (w/v) NaCl, was isolated from Yangshapao Lake, Jilin Province, China. Cells of this strain is Gram-positive, straight rods and form a central or sub-terminal ellipsoidal endospore. Phylogenetic analysis based on 16S rRNA gene sequences indicated that it was grouped in the genus Bacillus with Bacillus aurantiacus K1-5T and Bacillus populi FJAT-45347T as the close relative (97.5 and 97.2% 16S rRNA gene sequence similarity, respectively). Genomic relatedness between strain YSP-3T and its close relative was evaluated using average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity with the values of 70.3-85.1%, 19.7-20.1% and 71.5-71.6%, respectively. Comparative genomics analysis showed that strain YSP-3T has distinct amino acid bias and significantly differences from foreign invasion events during evolution relative to the reference strains. Cell-wall peptidoglycan contains meso-diaminopimelic acid. The predominant polar lipids are phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol. The predominant quinone is menaquinone-7. The major fatty acids of strain YSP-3T are anteiso-C15:0, iso-C15:0, iso-C16:0, anteiso-C17:0 and Iso-C14:0. DNA G + C content of strain YSP-3T is 48.3mol%. Based on genomics analysis, physiological, biochemical and chemotaxonomic data, strain YSP-3T represent a novel species, for which the name Bacillus lacisalsi sp. nov. is proposed. The type strain is YSP-3T ( = ACCC 60365T = KCTC 33934T).

Depositional environments in an arid, closed basin and their implications for oil and gas exploration: The lower Permian Fengcheng Formation in the Junggar Basin, China

The Fengcheng Formation is a nonmarine, carbonate-dominated succession that formed under arid climatic conditions in a hydrologically closed basin. Two transects and two seismic profiles were examined, the characteristics and environmental significance of different lithofacies were studied, and a model of depositional environment divisions was proposed. The sedimentary model involved an alkaline lake in which the depositional environments consisted of a shallow saline lake margin, slope, saline lake center, and steep lake margin from northeast to southwest. The perennial central salty lake was located in the southwestern part of the study area, whereas there were widespread, low-gradient lake margins in the northeast, east, southeast, and southern parts of the study area. Lake-level fluctuations had a major influence on the shallow saline lake system and complicated the depositional environments in these areas. The deposits are derived from bedrock reworking, volcanic eruptions, and authigenic minerals that precipitated from brine during the hypersaline phase. Fine-grained terrigenous clastic sediments, volcanic ashes and dusts, and authigenic minerals mixed in the depocenter (concentration center of the brine pool), which was covered by high-salinity brines, and the depositional environment was anoxic as a result of salinity-based brine stratification. A thick sodium carbonate succession occurred in the depocenter of the ancient Mahu lake, where bedded sodium carbonate alternated with fine-grained, organic-rich tuff or tuffaceous hydrocarbon source rocks. Microorganisms bloomed in the alkaline, high-salinity brine, and the organic matter was well preserved, which is similar to those modern alkaline saline lakes in eastern Africa and western North America. Thus, the Permian Fengcheng Formation contains source rocks that formed in an alkaline saline lake.

Chlorophyll a fluorescence analysis reveals divergent photosystem II responses to saline, alkaline and saline–alkaline stresses in the two Lotus japonicus model ecotypes MG20 and Gifu-129

Saline and alkaline stresses affect more than 10% of the World’s arable land, limiting agricultural production. Salt-induced stress may affect the photosystem II (PSII) function, altering fluorescence emission. Therefore, changes in fluorescence are used to quantify and analyze abiotic stress responses in plants. So far, no study has focused on the response of PSII to saline, alkaline and saline–alkaline stresses in the model legume Lotus japonicus. For the saline, alkaline and saline–alkaline treatments, plants of the L. japonicus ecotypes MG20 and Gifu-129 were cultivated in sand with nutrient solution, added with NaCl and NaHCO3 in different proportions. Growth, gas exchange, and chlorophyll a fluorescence transient kinetic and OJIP parameters were measured, and chlorophyll a and b were determined. The analysis of the kinetic of chlorophyll a fluorescence showed that NaCl-derived stress sources affect the photochemical events in PSII in both ecotypes, being this effect more evident under higher pH condition, whereas alkalinity per se has a mild or no effect on these events. The saline–alkaline stress induced a more severe effect on Gifu B-129, compared with Miyakojima MG20, whereas NaCl improved primary photochemistry in MG20. Our results allow us to accept the hypothesis that both ecotypes deploy differential responses under the three stressful treatments and that the saline–alkaline stress causes higher damage levels than saline and alkaline stresses alone in relation with structures and sub-processes of the PSII.

Hydrothermal origin of early Permian saddle dolomites in the Junggar Basin, NW China

Hydrothermal-related saddle dolomites widely exist in the lower Permian Fengcheng Formation in the northwestern Junggar Basin, and this formation is a set of carbonate-rich deposits in an alkaline saline basin. Core and thin section observations, cathodoluminescence (CL) imaging, and carbon and oxygen isotope composition analyses have been used to study the origins of saddle dolomites with various occurrences. Hydrothermal fluids include Si-rich and Si-poor fluids, and saddle dolomites occur, along with siliceous bands, as debris and assemblages in fragmented rocks and as cements filling pores and microfractures. Different types of dolomites in the Fengcheng Formation have similar δ13C values, while the δ18O values differed from each other, which demonstrated that the dolomites originated from the same primary carbonates and underwent multiple stages of recrystallization. The δ18O values were extremely negative, which was caused by fractionation at high temperatures from hydrothermal fluids. Dolomites are directly or indirectly affected by hydrothermal diagenetic fluids. According to the diagenetic stages, the types of migration paths for hydrothermal fluids, and the patterns of hydrothermal fluids acting on the dolomites, a model was proposed to illustrate the origins and evolution of the dolomites, and three paths were utilized. Path I occurred during the contemporaneous diagenetic stage, when the carbonate particles were still free and could be captured by high-density bottom hydrothermal flows and distorted. Path II occurred during the long diagenetic history after the carbonate-bearing sediments had consolidated. Saddle dolomite assemblages and saddle dolomite debris occurred with the aid of compressive tectonic forces. Path III also occurred in the long diagenetic history, and the host rocks were not fragmented. The saddle dolomites reprecipitated as cements in the pores, stylolites, fractures/microfractures or laminated seams.

Response of seedling growth and physiology of Sorghum bicolor (L.) Moench to saline-alkali stress.

Soil salinization is a serious problem that affects the seedling growth in many regions. A greenhouse experiment was carried to investigate the adaptation ability of seedlings (Sorghum bicolor (L.) Moench.) in coastal saline alkaline environment. Seedlings of sorghum were treated by different salt and alkali stress (NaCl: Na2SO4: NaHCO3 were 2:1:0, 2:1:1, 2:1:2). The treatments consisted of three levels of salinity (100, 200 and 300 mmol/L) and pH values were 7.08, 8.78 and 9.04. The results showed that the seedlings of sorghum have good adaptability to salt stress under low pH (pH ≤7.08). The plant height, the maximum leave areas of seedlings all dropped and root length first ascended and then descended with the increasing of salt and alkali stress. The contents of Chlorophyll b degraded significantly under salt and alkali stress. Salt and alkali stress stimulated the accumulation of organic solutes (proline and protein) and inorganic ions (Na+, Cl-, SO42-). Our results showed that salt and alkali stress have significant effect on growth indexes except root length and the interaction effect has significantly on physiology.

Isolation and identification of a halophilic and alkaliphilic microalgal strain.

Halophilic and alkaliphilic microalgal strain SAE1 was isolated from the saline–alkaline soil of Songnen Plain of Northeast China. Morphological observation revealed that SAE1 has a simple cellular structure, single cell, spherical, diameter of four to six μm, cell wall of about 0.22 μm thick, two chloroplasts and one nucleus. Analysis of the phylogenetic tree constructed by 18S sequence homology suggests that SAE1 is highly homologous to Nannochloris sp. BLD-15, with only four base substitutions in the homologous region. SAE1 was initially considered as Nannochloris sp. Analysis of the halophilic and alkaliphilic characteristics of SAE1 indicates that it can grow under one M NaHCO3 and NaCl concentrations, with optimal growth under 400 mM NaHCO3 and 200 mM NaCl. The intracellular ultrastructure of SAE1 significantly changed after NaCl and NaHCO3 treatments. A large number of starch grains accumulated after treatment with 400 mM NaHCO3 in cells, but few were found after treatment with 200 mM NaCl and none in the living condition without treatment. We conjectured that one of the metabolic characteristics of alkaliphilic (NaHCO3) microalga SAE1 is the formation of massive starch grains, which induce glycerol anabolism and increase osmotic pressure, thereby enhancing its ability to resist saline–sodic conditions. This feature of alkaliphilic (NaHCO3) microalga SAE1 contributes to its growth in the carbonate soil of Songnen Plain.

Responses of soil microbial communities and their network interactions to saline-alkaline stress in Cd-contaminated soils

Land degradation by salinization and sodification changes soil function, destroys soil health, and promotes bioaccumulation of heavy metals in plants, but little is known about their fundamental mechanisms in shaping microbial communities and regulating microbial interactions. In this study, we explored the impact of saline-alkaline (SA) stress on soil bacterial and fungal community structures in different Cd-contaminated soils of Dezhou, Baoding, Xinxiang, Beijing and Shenyang cities from the North China Plain, China. Increased soil salinity and alkalinity enhanced Cd availability, indicated by significant increases in available Cd2+ in soil solution of 34.1%–49.7%, soil extractable Cd of 32.0–51.6% and wheat root Cd concentration of 24.5%–40.2%, as well as decreased activities of antioxidative enzymes of wheat root when compared with CK (no extra neutral or alkaline salts added). Soil bacteria were more active in response to the SA stress than fungi, as the significant structural reorganization of soil bacterial microbiota rather than fungal microbiota between SA and CK treatments was illustrated by principal component analysis. Adding neutral and alkaline salts enriched oligotrophic and haloalkaliphilic taxa in the Sphingobacteriaceae, Cellvibrionaceae, and Caulobacteraceae bacterial families, but decreased some Acidobacteria such as subgroup 6_norank, which was a sensitive biomarker that responded only to Cd contamination in CK-treated soils. Conversely, fungi were more sensitive to soil differences than bacteria: the composition of the fungal community was significantly different among different soil types. Phylogenetic molecular ecological network (pMEN) analysis further indicated that the microbial community structure and network interactions were altered to strengthen the adaptability of microorganisms to SA stress; the changes in structure and network interactions were proposed to contribute to competitive interactions. Most of the keystone genera identified in SA-treated soils, such as Blastococcus, Gemmatimonas, RB41, or Candida, had relatively low abundances (<1%), indicating their disproportionate ecological roles in triggering resistance or tolerance to SA stress and Cd toxicity.

Bacterial and archaeal spatial distribution and its environmental drivers in an extremely haloalkaline soil at the landscape scale.

BackgroundA great number of studies have shown that the distribution of microorganisms in the soil is not random, but that their abundance changes along environmental gradients (spatial patterns). The present study examined the spatial variability of the physicochemical characteristics of an extreme alkaline saline soil and how they controlled the archaeal and bacterial communities so as to determine the main spatial community drivers.MethodsThe archaeal and bacterial community structure, and soil characteristics were determined at 13 points along a 211 m transect in the former lake Texcoco. Geostatistical techniques were used to describe spatial patterns of the microbial community and soil characteristics and determine soil properties that defined the prokaryotic community structure.ResultsA high variability in electrolytic conductivity (EC) and water content (WC) was found. Euryarchaeota dominated Archaea, except when the EC was low. Proteobacteria, Bacteroidetes and Actinobacteria were the dominant bacterial phyla independent of large variations in certain soil characteristics. Multivariate analysis showed that soil WC affected the archaeal community structure and a geostatistical analysis found that variation in the relative abundance of Euryarchaeota was controlled by EC. The bacterial alpha diversity was less controlled by soil characteristics at the scale of this study than the archaeal alpha diversity.DiscussionResults indicated that WC and EC played a major role in driving the microbial communities distribution and scale and sampling strategies were important to define spatial patterns.

The microbial community in an alkaline saline sediment of a former maar lake bed

The “Hoya del Rincon de Parangueo (HRP)” is a maar that contained a perennial alkaline lake that drained in the 1980s so that a sediment with high pH and extreme salinity remained. The aim of this work was to determine how the bacterial and archaeal community was controlled by these extreme conditions. Sediment samples were collected from the 0–20-cm layer along a crater-wide transect. Physicochemical characteristics and the archaeal and bacterial community were determined by analysis of the 16S rRNA through Illumina sequencing. The sediment samples had a pH 10 and an electrolytic conductivity (EC) that ranged from 29.8 to 74.4 dS m−1. Three archaeal and 37 bacterial phyla were detected with Euryarchaeota (relative abundance 62.7 ± 17.6%) dominating the Archaea, and Proteobacteria (28.2 ± 10.7%) and Actinobacteria (21.1 ± 6.4%) the Bacteria. The most abundant archaeal genus was Candidatus Nitrososphaera while Euzebya, Halomonas, KSA1 and Planctomycetes dominated the bacterial gene. Thaumarchaeota were enriched in sediment samples with a higher Pb content and Euryarchaeota in sediment with a higher Mg content, while Crenarchaeota and Candidatus Nitrososphaera were enriched in sediment with a higher sand, total N and organic C content. Proteobacteria were enriched in sediment with a higher organic C and total N, Si and sand content, while Bacteroidetes and Planctomycetes in sediment with a higher water holding capacity and clay and Mg content. Members of KSA1 and Euzebya were enriched in sediment with a lower EC, organic C and total N content. Although a large number of bacterial and archaeal groups were correlated significantly with a range of sediment characteristics, the sediment characteristics explained the variation of only two bacterial groups > 50% (TM6 and Desulfonatronospira) using the machine learning tool randomForest and none of the archaeal groups. Archaeal and bacterial functional guilds were dominated by ammonium oxidation and nitrite reduction. Although the different sediment samples were dominated often by similar bacterial and archaeal groups, the measured sediment characteristics explained little of the variation found between the sampling points. The high bacterial and archaeal diversity indicated that the site might be a source of unclassified species and phylotypes with specific metabolic capacities involved in the N and S cycles.

Bioturbation in matgrounds at Lake Bogoria in the Kenya Rift Valley: implications for interpreting the heterogeneous early Cambrian seafloor

Modern burrowing organisms feed on microbial organic matter in matgrounds near hot springs on the margins of Lake Bogoria, a saline alkaline lake in the Kenya Rift Valley. The burrowers produce a low-diversity trace assemblage similar to those produced by undermat miners during the Ediacaran–Cambrian transition. Despite obvious differences in body plans and phylogenetic affinities, these modern animals feed on microbes in similar ways to those inferred for primitive bilaterians. With increasing distance from hot-spring vents, outflow channels and adjacent matgrounds, the diversity and depth of the traces increase and mixgrounds become dominant. This modern extreme environment gives clues for interpreting the heterogeneous early Cambrian seafloor, with: (1) the restriction of ‘pre-agronomic revolution’ matground substrates; and (2) expansion of adjacent ‘post-agronomic revolution’ mixground areas.

Comparative Study of the Effects of Acute In Vitro and Short‐term In Vivo Treatments with 3, 5, 3′ Triiodo‐L‐Thyronine on Contractile Responsiveness of Isolated Rat Thoracic Aorta

This work was aimed to study comparatively the influences of acute in vitro and short‐term in vivo treatments with 3, 5, 3′ triiodo‐L‐thyronine (T3) on the contractile responsiveness of isolated rat thoracic aortas. Previous studies have reported that T3 through nongenomic and genomic mechanisms can elicit endothelium‐dependent and ‐independent, nitric oxide (NO)‐mediated, depression of vascular tone. Short‐term in vivo treatment (hyperthyroidism) was established by subcutaneous injections of T3 (500 mg/kg/day) for 3 days (T33d); while control rats received vehicle (alkaline saline solution) for 3 days (V3d). T33d treatment was sufficient to cause both significant weight loss and elevation of T3 serum levels in the rat. In endothelium‐intact aortic rings contracted with phenylephrine, in vitro application of increasing cumulative concentrations of T3, each 30 minutes (0.01, 0.1, 1 and 10 mM), did not alter the contractile tone compared to vehicle treated tissues. Likewise, in vitro treatment with T3 (0.1, 1 and 10 mM for 30 min or 2 hs) did not modify the relaxant responses induced by either acetylcholine or sodium nitroprusside, in that order, in endothelium‐intact and ‐denuded aortic rings contracted with phenylephrine. (In aortic rings with and without endothelium, phenylephrine‐induced precontractions were not modified by preceding exposure to T3 compared to their corresponding vehicle‐treated tissues.) The concentration‐dependent contractions caused by phenylephrine and angiotensin II in aortic rings with endothelium, remained unchanged in the presence of T3 (0.1, 1 and 10 mM) applied 30 min or 2 h before. On the other hand, T33d treatment significantly decreased the contractile responses induced by phenylephrine and angiotensin II in aortic rings with and without endothelium, related to their respective controls. The absence of endothelium or the addition of the NO synthase inhibitor, L‐NAME, in the presence of endothelium (100 mM), independently, enhanced the contractile responses to phenylephrine in aortic rings of T33d and V3d rats. However, the contractile responses to phenylephrine remained similarly depressed in endothelium‐denuded and endothelium‐intact L‐NAME‐treated aortas of T33d compared to V3d rats. In conclusion, T3 applied in vitro does not alter the development of active tone in the endothelium‐intact and ‐denuded thoracic aortas, which rules out a direct action, by a rapid non‐genomic mechanism, of this hormone in smooth muscle and endothelial cells. On the other hand, short‐term in vivo administration of T3 depressed contractile responsiveness of the thoracic aorta, independently of endothelium and NO (whether of endothelial or muscle origin). It remains to elucidate if the T3‐induced depression of aortic contractility is due to direct hormonal effects or is secondary to a hyperdynamic cardiovascular state in hyperthyroid rats.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Fine-scale characteristics of the boundaries between annual patches and perennial patches in a meadow steppe

Boundaries may have crucial influences on landscape patterns, processes, and dynamics. However, there is little understanding of mechanisms that govern changes in the location and composition of boundaries. At smaller scales, investigation of detailed soil and vegetation characteristics can clarify the linkages between soil properties and vegetation patterns. The aims were to examine the relationship between vegetation patterns and soil properties, and to explore mechanisms that govern changes in the location and composition of boundaries. In a 50-ha grassland fenced for more than 10 years, where a recovery process had been initiated and annual grasses dominated in most saline–alkaline areas, we quantitatively characterized the spatial gradients across the visually identified physiognomic boundary between annual patches and perennial patches at a fine spatial scale. Fine-scale vegetation and soil boundaries were well-defined and statistically characterized by a high rate of change compared to immediately adjacent areas. Plant characteristics were markedly influenced by soil properties. The alteration of salinity and alkalinity were the most important factors explaining the plant patterns across patch boundaries. Successional processes of colonization were involved in perennial encroachment in the annual patches. Underlying soil properties primarily determine the plant patterns of the boundary; plant succession caused by interspecific competition is superimposed on the plant–soil feedback loop maintaining soil nutrient conditions. These processes alter the characteristics and locations of patch boundaries in response to changing disturbance regimes. Our findings offer insight into how boundaries may respond to changes in environmental conditions and drive landscape-level dynamics.

Characterization, functional analysis, and expression levels of three carbonic anhydrases in response to pH and saline–alkaline stresses in the ridgetail white prawn Exopalaemon carinicauda

Carbonate alkalinity, salinity, and pH are three important stress factors for aquatic animals in saline-alkaline water. Carbonic anhydrases (CAs) catalyze the reversible reaction of CO2 reported to play an important role in the acid-base regulation in vertebrates. To explore the molecular mechanism of CAs efficacy in shrimp after their transfer into saline-alkaline water, the cDNAs of three CAs (EcCAc, EcCAg, and EcCAb) were cloned from Exopalaemon carinicauda. Sequence analysis showed that EcCAc and EcCAg both possessed a conserved α-CA domain and a proton acceptor site, and EcCAb contained a Pro-CA domain. Tissue expression analysis demonstrated that EcCAc and EcCAg were most abundantly in gills, and EcCAb was highly expressed in muscle. The cumulative mortalities remained below 25% under exposure to pH (pH6 and pH9), low salinity (5ppt), or high carbonate alkalinity (5 and 10mmol/L) after 72h of exposure. However, mortalities increased up to 70% under extreme saline-alkaline stress (salinity 5ppt, carbonate alkalinity 10mmol/L, and pH9) after 14days of exposure. The EcCAc and EcCAg expressions in gills were significantly upregulated during the early period of pH and saline-alkaline stresses, while the EcCAb expressions showed no regular or large changes. The two-way ANOVA found significant interactions between salinity and carbonate alkalinity observed in EcCAc, EcCAg, and EcCAb expressions (p < 0.05). Furthermore, an RNA interference experiment resulted in increased mortality of EcCAc- and EcCAg-silenced prawns under saline-alkaline stress. EcCAc knockdown reduced expressions of Na+/H+ exchanger (EcNHE) and sodium bicarbonate cotransporter (EcNBC), and EcCAg knockdown reduced EcCAc, EcNHE, EcNBC, and V-type H+-ATPase (EcVTP) expressions. These results suggest EcCAc and EcCAg as important modulators in response to pH and saline-alkaline stresses in E. carinicauda.

Interaction between lakes’ surface water and groundwater in the Pantanal wetland, Brazil

The Nhecolândia subregion (area ~ 26,921 km2), in central-southern Pantanal, is marked by the presence of hundreds of alkaline–saline lakes, located on the top of sand hills, and thousands of non-alkaline lakes adjacent to the sand hills. This study aimed to provide a better understanding of the hydrological dynamics in the Nhecolândia, which is scarce and controversial, based on piezometric monitoring, isotopic data and chemical analyses of the surface water and groundwater of an alkaline–saline lake, a non-alkaline lake and the sand hill between them. The potentiometric data indicated that both alkaline–saline and non-alkaline lakes act as recharge zones, the former in all seasons and the later only in the wet season. These results are corroborated by downward flow near the zones of recharge, indicated by hydraulic head measurements in multilevel wells around the non-alkaline lake and in mini-piezometers installed in the studied alkaline–saline lake and two more lakes in the region. Also, δ18O and δ2H values of the alkaline–saline lake surface water became more depleted than the surrounding groundwater in the wet season, confirming that the inflow to the alkaline–saline lake in this season was by the more depleted rainwater and not by the isotopically enriched groundwater. The water chemistry data is also in agreement with recharge from the alkaline–saline lake, even though this recharge is limited by a low-K layer. Because of this layer, the non-alkaline lake does not dry off during the dry season. This set of evidence demonstrated that the groundwater recharge in the study area occurs in the topographical lows, through a process known as depression-focused recharge, which disagrees with previous studies of the area.