Elemental Composition of Extremely Alkaliphilic Anaerobic Bacteria

The contents of several chemical elements were assessed in the haloalkaliphilic acetogenic bacterium Natroniella acetigena and the alkaliphilic sulfate-reducing bacterium Desulfonatronum lacustre using X-ray microanalysis, stereoscanning microscopy, and mass spectrometry. The organisms were found to differ significantly in their relative contents of S, K, P, and Cl. The P/S ratio in cells of the alkaliphilic bacteria incubated in mineral media at different pH was pH-dependent. With a pH increase from 9 to 10, potassium extrusion from cells was observed, suggesting that secondary K⁺/H⁺ antiport activity accounts for the homeostasis of cytosolic pH. Deenergization of bacterial cells in the presence of inhibitors and ionophores results in specific changes in the P/S ratio, which may be considered an indicator of the cell energetic state. In Natroniella acetigena, the content of intracellular Cl was directly proportional to the NaCl concentration in the medium. Some metals were shown to be necessary for the N. acetigena viability; the requirement for Ni and Co was absolute. Although little demand for Mg was characteristic of the bacteria studied, their growth was stimulated by an increase in Mg concentration, and the cell resistance to lysis was enhanced.     

Difference in ionic specificity of ATP synthesis in extremely alkalophilic sulfate-reducing and acetogenic bacteria

Ionic specificity of oxidative phosphorylation was studied in Natroniella acetigena and Desulfonatronum lacustre, which are new alkaliphilic anaerobes that were isolated from soda lakes and have a pH growth optimum of 9.5-9.7. The ability of their cells to synthesize ATP in response to the imposition of artificial delta pH+ and delta pNa+ gradients was studied. As distinct from other marine and freshwater sulfate reducers and extremely alkaliphilic anaerobes, D. lacustre uses a Na(+)-translocating ATPase for ATP synthesis. The alkaliphilic acetogen N. acetigena, which develops at a much higher Na+ concentration in the medium, generated primary delta pH+ for ATP synthesis. Thus, the high Na+ concentrations and alkaline pH values typical of soda lakes do not predetermine the type of bioenergetics of their inhabitants.     

Carboanhydrase activity in halophilic anaerobes from soda lakes

The activity and cellular localization of carboanhydrase (CA) in two alkaliphilic anaerobes growing in soda lakes at pH 9-10 was studied. CA activity in the cell extracts of the acetogenic bacterium Natroniella acetigena was comparable to that of the neutrophilic acetogens. Hydrogenotrophically grown cells of Desulfonatronum lacustre exhibited higher CA activity compared to the cells grown on media with formate. High CA activity in the cytoplasmic fraction and the absence of high activity in the extracellular fraction were demonstrated. We propose that the cytoplasmic CA in alkaliphilic sulfate-reducers participates in conversion of bicarbonate to CO2, which is reduced in the cell to acetate via the acetyl-CoA pathway.     

Osmoadaptation in representatives of haloalkaliphilic bacteria from soda lakes

The adaptation of microorganisms to life in brines allows two strategies: the accumulation of organic osmoregulators in the cell (as in many moderate halophiles, halomonads in particular) or the accumulation of inorganic ions at extremely high intracellular concentrations (as, for example, in haloanaerobes). To reveal the regularities of osmoregulation in haloalkaliphiles developing in soda lakes, Halomonas campisalis Z-7398-2 and Halomonas sp. AIR-2 were chosen as representatives of halomonads, and Natroniella acetigena, as a representative of haloanaerobes. It was established that, in alkaliphilic halomonads, the intracellular concentrations of inorganic ions are insufficient for counterbalancing the environmental osmotic pressure and balance is attained due to the accumulation of organic osmoregulators, such as ectoine and betaine. On the contrary, the alkaliphilic haloanaerobe N. acetigena employs K+, Na+, and Cl- ions for osmoregulation. High intracellular salt concentrations increasing with the content of Na+ in the medium were revealed in this organism. At a concentration of 1.91 M Na+ in the medium, N. acetigena accumulated 0.83 M K+, 0.91 M Na+, and 0.29 M Cl- in cells, and, with an increase in the Na+ content in the medium to 2.59 M, it accumulated 0.94 M K+, 1.98 M Na+, and 0.89 M Cl-, which counterbalanced the external osmotic pressure and provided for cell turgor. Thus, it was shown that alkaliphilic microorganisms use osmoregulation strategies similar to those of halophiles and these mechanisms are independent of the mechanism of pH homeostasis.     

Carbonic anhydrase activity in halophilic anaerobes from soda lakes

The activity and cellular localization of carbonic anhydrase (CA) in two alkaliphilic anaerobes growing in soda lakes at pH 9–10 were studied. CA activity in the cell extracts of the acetogenic bacterium Natroniella acetigena was comparable to that of neutrophilic acetogens. Hydrogenotrophically grown cells of Desulfonatronum lacustre exhibited higher CA activity compared to the cells grown on medium with formate. High CA activity in the cytoplasmic fraction and the absence of high activity in the extracellular fraction were demonstrated. We propose that the cytoplasmic CA in alkaliphilic sulfate-reducers participates in conversion of bicarbonate to CO₂, which is reduced in the cell to acetate via the acetyl-CoA pathway.     

Relationships between the osmoadaptation strategy, amino acid composition of total cellular protein, and properties of certain enzymes of haloalkaliphilic bacteria

Haloalkaliphilic microorganisms isolated from soda lakes were compared in terms of the amino acid composition of total cellular protein and the reaction of a number of key enzymes to salts and pH of the medium. In the extremely halophilic bacterium Natroniella acetigena (salt-inside osmoadaptation strategy), acidic amino acids (glutamic and aspartic) made up 30.91 mol % of the total of cellular protein amino acids. In the moderate haloalkaliphiles Tindallia magadiensis, Halomonas campisalis, and Halomonas sp. AIR-1 (compatible-solutes osmoadaptation strategy), the proportion of acidic amino acids (24.36, 23.15, and 23.58 mol %, respectively) was lower than in N. acetigena but higher than in the freshwater Acetobacterium paludosum (20.77 mol %). The excess of acidic amino acids over basic amino acids (lysine and arginine) increased with the degree of halophily. The enzymes of haloalkaliphiles proved to be tolerant to salts and high pH values, although the degree of tolerance varied. The activity of N. acetigena CO dehydrogenase was maximum in the presence of 0.7 M NaCl, but it was virtually independent of the NaHCO3 concentration. The hydrogenase and CO dehydrogenase of T. magadiensis exhibited maximum activity in the absence of NaCl; the CO dehydrogenase was most active at 0.25 M NaHCO3, and hydrogenase activity was only weakly dependent on NaHCO3 in the concentration range of 0-1.2 M. The nitrate reductases of H. campisalis and Halomonas sp. AIR-2 were active in broad ranges of NaCl and KCl concentrations; the activity maxima were recorded at moderate concentrations of these salts. The pH optima of most of the studied enzymes of haloalkaliphiles were in the alkaline zone. Thus, it was shown that the amino acid composition of total cellular protein is determined by the osmoadaptation strategy employed by the bacterium. A correlation was found between the salt tolerance of enzymes and the proportion of acidic amino acids in the total cellular protein. The ability of enzymes to function at high pH values is one of the mechanisms of adaptation of microorganisms to high pH values.     

Cation transport in Serratia marcescens and Serratia marinorubra

The sodium, potassium, and magnesium ion contents of Serratia marcescens and those of its salt-tolerant relative, S. marinoruba, were determined by atomic-absorption spectrometry. The intracellular K(+) and Mg(2+) contents of both microorganisms were found to be dependent on the ionic strength of the growth or suspending medium. The Mg(2+) content of S. marinoruba was generally greater than that of S. marcescens. The Na(+) content of the cells was normally low and did not increase as the cells aged or when the cells were grown in media of high ionic strength. The transport of K(+) by resting cells suspended in hypertonic solution was studied by chemical and light-scattering techniques and was found to be more rapid in S. marcescens than in S. marinorubra. The slower rate of K(+) transport in S. marinorubra is probably related to the lower glycogen reserves found in resting cells of this microorganism. K(+) transport was found to have a pH optimum of 5.5 to 6.1 for S. marcescens, and the K(m) for K(+) was approximately 1.6 mm. Na(+) and Mg(2+) were not taken up by the cells, although the presence of Mg(2+) tended to decrease rates of K(+) uptake. Tris-(hydroxymethyl)aminomethane, routinely used for resuspending the cells, was apparently taken up by the cells at pH >7.     

A thermodynamic study of electroneutral K-Cl cotransport in pH- and volume-clamped low K sheep erythrocytes with normal and low internal magnesium

Swelling-induced human erythrocyte K-Cl cotransport is membrane potential independent and capable of uphill transport. However, a complete thermodynamic analysis of basal and stimulated K-Cl cotransport, at constant cell volume, is missing. This study was performed in low K sheep red blood cells before and after reducing cellular free Mg into the nanomolar range with the divalent cation ionophore A23187 and a chelator, an intervention known to stimulate K- Cl cotransport. The anion exchange inhibitor 4,4''diisothiocyanato- 2,2''disulfonic stilbene was used to clamp intracellular pH and Cl or NO3 concentrations. Cell volume was maintained constant as external and internal pH differed by more than two units. K-Cl cotransport was calculated from the K effluxes and Rb (as K congener) influxes measured in Cl and NO3, at constant internal K and external anions, and variable concentrations of extracellular Rb and internal anions, respectively. The external Rb concentration at which net K-Cl cotransport is zero was defined as flux reversal point which changed with internal pH and hence Cl. Plots of the ratio of external Rb concentrations corresponding to the flux reversal points and the internal K concentration versus the ratio of the internal and external Cl concentrations (i.e., the Donnan ratio of the transported ions) yielded slopes near unity for both control and low internal Mg cells. Thus, basal as well as low internal Mg-stimulated net K-Cl cotransport depends on the electrochemical potential gradient of KCl.     

Intracellular inclusions of uncultured magnetotactic bacteria.

Magnetotactic bacteria produce magnetic crystals in organelles called magnetosomes. The bacterial cells may also have phosphorus-containing granules, sulfur globules, or polyhydroxyalkanoate inclusions. In the present study, the ultrastructure and elemental composition of intracellular inclusions from uncultured magnetotactic bacteria collected in a marine environment are described. Magnetosomes contained mainly defect-free, single magnetite crystals with prismatic morphologies. Two types of phosphorus-containing granules were found in magnetotactic cocci. The most common consisted of phosphorus-rich granules containing P, O, and Mg; and sometimes also C, Na, Al, K, Ca, Mn, Fe, Zn, and small amounts of S and Cl were also found. In phosphorus-sulfur-iron granules, P, O, S, Na, Mg, Ca, Fe, and frequently Cl, K, and Zn, were detected. Most cells had two phosphorus-rich granules, which were very similar in elemental composition. In rod-shaped bacteria, these granules were positioned at a specific location in the cell, suggesting a high level of intracellular organization. Polyhydroxyalkanoate granules and sulfur globules were less commonly seen in the cells and had no fixed number or specific location. The presence and composition of these intracellular structures provide clues regarding the physiology of the bacteria that harbor them and the characteristics of the microenvironments where they thrive.     

小麦籽粒不同部位的矿质元素组成与其含量差异

采用X-射线能谱仪测定非糯与糯性等品种小麦籽粒不同部位的矿质元素组成(H和He元素除外)和含量的结果表明:小麦籽粒中除含有大量C、O外,皮层富含K、P、se,其次是Cl、Si、S、Mg和Ca等;糊粉层富含P、K和Mg,其次是Si、Se、S、Ca、Cl和Fe等;胚乳层中相应的矿质元素含量比皮层和糊粉层低。不同品种籽粒各部位的矿质元素含量存在遗传性差异。据此认为籽粒磨成粉时应减少糊粉层的损失,以提高面粉的矿质价值。     

霍山石斛组培苗移栽后微观结构与微区元素的变化研究

采用扫描电镜及X射线能谱仪技术,研究霍山石斛组培苗移栽后各器官组织的微观结构和所含元素的变化,以了解霍山石斛组培苗生长发育以及药效成分的状况。结果表明:(1)霍山石斛组培苗移栽2个月后,根增粗近1倍,具有根被,且根被细胞壁的网络状增厚更加明显,表皮、皮层、中柱发育分化更加完善,Mg、Si、Cl、S、K、Ca元素含量提高,其中Ca增长了2.76倍。(2)茎表面纵向凹陷增多,内部结构致密,维管束发育较为完善,细胞内充满物质,Mg、Si、Cl、S、K、Ca、Fe、Cu、Zn元素含量增多,尤其是K和Fe分别增长了3.25倍和4.61倍。(3)叶增厚,具有了角质层,气孔形状更加饱满,叶肉细胞内含物丰富,Mg、Si、Cl、S、K、Ca、Fe、Mn、Zn的含量显著上升,其中K升高了17倍。(4)与根、叶相比,茎中所富集的元素种类最多。研究认为,霍山石斛试管苗移栽后,生长发育趋向完善,各项功能增强,细胞内含物质增多,元素成分丰富并且含量提高,体现出对移栽环境的良好适应性。     

"Candidatus contubernalis alkalaceticum," an obligately syntrophic alkaliphilic bacterium capable of anaerobic acetate oxidation in a coculture with Desulfonatronum cooperativum

From the silty sediments of the Khadyn soda lake (Tuva), a binary sulfidogenic bacterial association capable of syntrophic acetate oxidation at pH 10.0 was isolated. An obligately syntrophic, gram-positive, spore-forming alkaliphilic rod-shaped bacterium performs acetate oxidation in a syntrophic association with a hydrogenotrophic, alkaliphilic sulfate-reducing bacterium; the latter organism was previously isolated and characterized as the new species Desulfonatronum cooperativum. Other sulfate-reducing bacteria of the genera Desulfonatronum and Desulfonatronovibrio can also act as the hydrogenotrophic partner. Apart from acetate, the syntrophic culture can oxidize ethanol, propanol, isopropanol, serine, fructose, and isobutyric acid. Selective amplification of 16S rRNA gene fragments of the acetate-utilizing syntrophic component of the binary culture was performed; it was found to cluster with clones of uncultured gram-positive bacteria within the family Syntrophomonadaceae. The acetate-oxidizing bacterium is thus the first representative of this cluster obtained in a laboratory culture. Based on its phylogenetic position, the new acetate-oxidizing syntrophic bacterium is proposed to be assigned, in a Candidate status, to a new genus and species: "Candidatus Contubernalis alkalaceticum."     

Elemental maps in human allantochorial placental vessels cells. 3. 5-hydroxytryptamine effects.

The membrane potential, a regulator of vascular tone, is a function of the physiological activities of ionic channels (particularly, K+ and Ca2+ channels in these cells). These channels regulate the ionic distribution into these cells. Micro-particule induced X-ray emission (PIXE) analysis was applied to determine the ionic composition of vascular smooth muscle cells (VSMCs) and of vascular endothelial cells (VECs) in the placental human allantochorial vessels in a physiological medium (Hanks'solution) modified by the addition of a chemical stimulus: 5-hydroxytryptamine (5-HT), an activator of the voltage-sensitive Ca2+ channels. In VSMCs (media layer), the addition of 5-HT induced no modification of the Na, K, Cl, P, S and Ca concentrations but increased Mg concentration. In endothelium (VECs) 5-HT addition implicated an increase of the K, S, Ca concentrations, the concentration of the other ions remained constant. In VECs, Ca and K increase is due to open of L-type voltage-dependent Ca2+ channels and of K(Ca) channels. 5-HT induces also a secretion of endothelium hyperpolarizing factors which implicate decrease of [Ca2+]i in VSMCs opposite to a direct increase by 5-HT. Increase in [Mg2+]i may be due to activation of the Ca/Mg exchanger.     

Distribution of N,P, K,Ca, Mg,S, Zn,Fe, Mn and Cu in groundnut

Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.     

A microprobe study of element distribution in vaginal epithelial cells of the rat

Microprobe analysis of vaginal epithelial cells shed during the estrous cycle of the rat was done to determine cellular elements present in successive stages: pro-estrus, estrus, and post-estrus. Smears of vaginal contents were placed on carbon planchettes, fixed by freeze-drying, and examined in a scanning microscope with an energy dispersive spectrometer. Concentrations of Na, Mg, P, S, Cl, K, and Ca were calculated (mmol/kg dry weight) and analyzed statistically. For phosphorus a significant fall at estrus correlates with a loss of nuclear and cytoplasmic nucleic acids and nucleoproteins. An increase in sulfur at estrus is consistent with an accumulation of keratins over pro-estrus and a greater increase over the post-estrus epithelial cells. The epithelial cells of pro-estrus are highest in Mg and Ca. By post-estrus, the cells have recovered their Mg, not Ca. Potassium concentrations exhibited no significant change between the successive stages.     

Biomass production,nutrient cycling,and carbon fixation by Salicornia brachiata Roxb.: A promising halophyte for coastal saline soil rehabilitation

In order to increase our understanding of the interaction of soil-halophyte (Salicornia brachiata) relations and phytoremediation, we investigated the aboveground biomass, carbon fixation, and nutrient composition (N, P, K, Na, Ca, and Mg) of S. brachiata using six sampling sites with varying characteristics over one growing season in intertidal marshes. Simultaneously, soil characteristics and nutrient concentrations were also estimated. There was a significant variation in soil characteristics and nutrient contents spatially (except pH) as well as temporally. Nutrient contents in aboveground biomass of S. brachiata were also significantly differed spatially (except C and Cl) as well as temporally. Aboveground biomass of S. brachiata ranged from 2.51 to 6.07 t/ha at maturity and it was positively correlated with soil electrical conductivity and available Na, whereas negatively with soil pH. The K/Na ratio in plant was below one, showing tolerance to salinity. The aboveground C fixation values ranged from 0.77 to 1.93 C t/ha at all six sampling sites. This study provides new understandings into nutrient cycling—C fixation potential of highly salt-tolerant halophyte S. brachiata growing on intertidal soils of India. S. brachiata have a potential for amelioration of the salinity due to higher Na bioaccumulation factor.     

不同解磷菌处理下巨尾桉幼苗不同部位干质量及氮、磷、钾含量的变化

采用高效解磷菌P19和P7(解无机磷)以及YP17(解有机磷),研究不同浓度单一及混合解磷菌处理对巨尾桉( Eucalyptus grandis Hill ex Maiden × E. urophylla S. T. Blake)幼苗干质量、氮和钾含量的影响以及叶片磷含量的动态变化。结果表明：用5×106、2×106和1×106 CFU·mL-1解磷菌单一及混合处理后,巨尾桉幼苗的地上部分和地下部分干质量、总干质量以及氮含量总体上高于空白对照( CKB )和供磷对照( CKP ,添加18 mg·kg-1 KH2 PO4),且总体上差异显著(P<0.05),而仅少数处理组的幼苗钾含量显著高于CKB和CKP。随处理时间延长,不同解磷菌处理组的叶片磷含量呈现不同的变化趋势,但不同月份间叶片磷含量差异极显著(P<0.01);各处理组的叶片磷含量平均值均高于CKB ,且混菌处理组总体上高于单菌处理组。方差分析结果表明：不同解磷菌和不同菌液浓度对幼苗总干质量的影响效应均有显著差异;二者对幼苗氮含量有极显著或显著影响,但二者的交互作用对幼苗氮含量无显著影响(P>0.05);不同解磷菌、不同菌液浓度及二者间的交互作用对幼苗钾含量均有极显著影响;不同解磷菌、不同菌液浓度、不同时间及三者间的交互作用对叶片磷含量均有极显著影响。多重比较结果表明：P19-YP17、P7-YP17和P7-P19处理对幼苗氮含量和叶片磷含量平均值的提升作用明显,YP17、P19-YP17和P7-P19处理对幼苗总干质量平均值的提升作用明显,不同解磷菌对幼苗钾含量平均值无显著提升作用;不同菌液浓度下幼苗的总干质量、氮和钾含量以及叶片磷含量的平均值总体上显著高于CKB,其中,中浓度(2×106 CFU·mL-1)和低浓度(1×106 CFU·mL-1)菌液处理对叶片磷含量以及幼苗氮和钾含量平均值的提升作用明显。综合分析结果显示：P19-YP17、P7-YP17和P19-YP17解磷菌混合处理对巨尾桉幼苗生长有明显的促进作用,可作为混合解磷菌剂加以进一步开发研究。     

Biphasic behavior of changes in elemental composition during staurosporine-induced apoptosis

Although the identification of events that occur during apoptosis is a fundamental goal of apoptotic cell death research, little is know about the precise sequence of changes in total elemental composition during apoptosis. We evaluated total elemental composition (Na, Mg, P, Cl, S, and K) in relation to molecular and morphological features in human U937 cells induced to undergo apoptosis with staurosporine, an intrinsic pathway activator. To evaluate total elemental content we used electron probe X-ray microanalysis to measure simultaneously all elements from single, individual cells. We observed two phases in the changes in elemental composition (mainly Na, Cl and K). The early phase was characterized by a decrease in intracellular K (P < 0.001) and Cl (P < 0.001) content concomitant with cell shrinkage, and preceded the increase in proteolytic activity associated with the activation of caspase-3. The later phase started with caspase-3 activation, and was characterized by a decrease in the K/Na ratio (P < 0.001) as a consequence of a significant decrease in K and increase in Na content. The inversion of intracellular K and Na content was related with the inhibition of Na⁺/K⁺ ATPase. This later phase was also characterized by a significant increase (P < 0.001) in intracellular Cl with respect to the early phase. In addition, we found a decrease in S content and an increase in the P/S ratio. These distinctive changes coincided with chromatin condensation and DNA fragmentation. Together, these findings support the concept that changes in total elemental composition take place in two phases related with molecular and morphological features during staurosporine-induced apoptosis.     

Magnesium secretion by the distal segment of the Malpighian tubules of the black field cricket Teleogryllus oceanicus

The short distal segment of unstimulated Teleogryllus Malpighian tubules secreted hyperosmotic fluid containing primarily Mg (125mmoll(-1)), Cl (242mmoll(-1)) and Na (43mmoll(-1)). Remarkably, the volume secreted by the distal segment in unit time was independent of segment length, i.e. the volume was constant regardless of the length of the segment. Magnesium was secreted at a rate of 75.5pmolmin(-1)mm(-1); the highest rate recorded for any epithelium. Low concentrations of K (20mmoll(-1)) were present but almost no P or S. Ca (2.5mmoll(-1)) concentration was higher than in the main segment. The short distal segment secreted 100% of the Mg, 54% of the Cl and 23% of the Na secreted by the whole tubule. The main segment secreted fluid containing primarily K (199mmoll(-1)), Cl (149mmoll(-1)), Na (104mmoll(-1)) and P (48mmoll(-1)) with very low concentrations of Ca (1mmoll(-1)) and S. The main segment appeared to reabsorb a small fraction of the Mg secreted by the distal segment. The fluid secreted by the whole tubule was isosmotic and alkaline, approximately pH8.