Effect of fatty acids on poly-amine contents and Na+/H+antiport activity in PM vesi-cles isolated from roots ofbarley under salt stress

With 200 mmol/L NaCI treatment on barleycultivar "Jian 4" (Hordeum vulgare L. cv. J4) seedlings for6 d, the contents of covalently and noncovalently conjugatedpolyamines (PAs) and activities of H+-ATPase in plasmamembrane (PM) vesicles isolated from the roots decreasedremarkably. Moreover, the activity of Na+/H+ antiport wasdetected first in PM vesicles. The results showed that thedecrease in the contents of membrane phospholipid, nonco-valently conjugated PAs and activity of H+-ATPase caused byNaCl could be restored partially by application of 1 mmol/Lstearic acid (C16:0) and linoleic acid (C18:2), and C18:2 wasmore effective than C16:0. In addition, a reduction in the con-tents of covalently conjugated PAs was only reversed par-tially in the presence of C18:2. Furthermore, Na+/H+ antiportactivity was strengthened by exogenous C16:0 and C18:2, andC18a was more effective than C16:0. The correlative analysissuggested that, after application of C16:0 and C18:2 under saltstress, there was a significant positive correlation existingamong phospholipid content, noncovalently conjugated PAlevels, H+-ATPase activities and Na+/H+ antiport activities,indicating that one of the mitigative mechanisms of exoge-nous fatty acids on salt injury was to improve membranephospholipid and PA contents, leading to an enhance inmembrane integrity and a change in charge status of PMvesicles, so the activity of membrane-associated enzymeH+-ATPase was increased and synthesis of Na+/H+ antiportprotein was activated.     

The short C-terminal hydrophilic domain of NhaH Na^＋/H^＋ antiporter from Halobacillus dabanensis with roles in resistance to salt and in pH sensing

The Na^＋/H^＋ antiporter plays key roles in maintaining low cytoplasmic NaNa^＋ level and pH homeostasis, while little is known about the Carboxyl-terminal hydrophilic tails of prokaryotic antiporters. In our previous study, the first Na^＋/H^＋ antiporter gene nhaH from moderate halophiles was cloned from Halobacillus dabanensis D-8 by functional complementation. A topological model suggested that only nine amino acid residues （^395PLIKKLGMI403） existed in the hydrophilic C-terminal domain of NhaH. The C-terminal truncated mutant of NhaH was constructed by PCR strategy and designated as nhaH△C. Salt tolerance experiment demonstrated that the deletion of hydrophilic C-terminal nine amino acid residues significantly inhibited the complementation ability of E. coil KNabc, in which three main Na^＋/H^＋ antiporters nhaA, nhaB and chaA were deleted. Everted membrane vesicles prepared from E. coil KNabc/nhaHAC decreased both Na^＋/H^＋ and Li^＋/H^＋ exchange activities of NhaH, and also resulted in an acidic shift of its pH profile for Na^＋, indicating a critical role of the short C-terminal domain of NhaH antiporter in alkali cation binding/translocation and pH sensing.     

H-ATPase in the plasma membrane of Arabidopsis pollen cells is involved in extracellular calmodulin-promoted pollen germination

In this paper, the role of the plasma membrane (PM) H⁺-ATPase in extracellular calmodulin (CaM)-promoted pollen germination and in tube growth of Arabidopsis thaliana was investigated. Pollen germination, pollen tube growth rate, free cytosolic Ca²⁺ concentration ([Ca²⁺]_cyt) and Ca²⁺ channel activity in the PM of pollen cells were measured. In response to fusicoccin or CaM treatment, in vitro pollen germination and pollen tube growth rate, [Ca²⁺]_cyt and activity of a hyperpolarization-activated Ca²⁺-permeable channel increased. Sodium vanadate inhibited the promotion of these parameters by extracellular CaM. The results suggest that H⁺-ATPase may be involved in extracellular CaM-regulated pollen germination and in tube growth by modulation of the hyperpolarization-activated Ca²⁺ channel in the PM of A. thaliana pollen cells.     

Na+-K+-ATP酶的π-演算语义及验证

给出了Na⁺-K⁺-ATP酶跨越细胞膜同时主动向胞内运转钾离子和向胞外运转钠离子这一生化过程的π-演算模型及该模型的Spin验证. 证明了用过程代数的方法表示以“相互通讯”和“可移动”为主要特征的生物系统并模拟其行为的可行性.      

Theoretical study of partial oxidation of ethylene by vanadium trioxide cluster cation

Density functional theory （DFT） study of reaction between vanadium trioxide cluster cation （VO3^＋） and ethylene （C2H4） to yield VO2^＋ ＋ CH3CHO （acetaldehyde） and VO2CH2^＋ ＋ HCHO （formaldehyde） is carried out. Structures of all reactants, products, intermediates, and transition state in the reaction have been optimized and characterized. The results show unexpected barriers in the reaction due to the existence of a η^2-O2 moiety in the ground state structure of VO3^＋. The initial reaction steps combining ethylene adsorption, C=C activation and O-O cleavage are proposed as rate limiting processes. Comparison of reactions of VO3^＋ ＋ C2H4 with VO3 ＋ C2H4 and VO2^＋ ＋ C2H4 in the previous studies is made in detail. The results of this work may shed light on the understanding of C=C bond cleavage in related heterogeneous catalysis.     

Cell responses ofDunaliella salina FACHB 435 (Green Alga) to microgravitational stimulation by clinorotation

Clinorotation experiments were established to simulate microgravity on ground. It was found that there were obvious changes ofDunaliella salina FACHB435 cells and their metabolic characteristics during clinorotation. The changes included the increases of glycerol content, the rate of H⁺ secretion and PM H⁺ -ATPase activity, and the decrease of ratio of the plasma membrane (PM) phospholipid to PM protein. These results indicated that microgravity was a stress environment toDunaliella salina. It is deduced that it would be possible to attribute the effect of microgravity on algal cells to the secondary activation of water stress.     

Circular dichroism spectroscopic studies on structures formed by telomeric DNA sequencesin vitro

Telomere plays an important role in cellular processes, such as cell aging, death and carcinogenisis. Having special sequences, it can form quadruplex structurein vitro. Circular dichroism (CD) spectroscopic studies show that TTAGGG, (TTAGGG)₂ and (TTAGGG)₄ can all form quadruplexin vitro and exist mainly as parallel quadruplex without metal ions. Both K⁺ and Na⁺ can stabilize the tetrameric structure and facilitate the forming of anti-parallel conformation. Furthermore, the conformations of quadruplex can also be affected by sequence length, the nature and concentration of metal ions.     

Impact of gamma radiation and salinity on growth and K+/Na+ balance in two populations of Medicago sativa (L.) cultivar Gabès

The perennial Medicago sativa cv. Gabès is widely grown on saline soils in Tunisian oases. Morphological and physiological analyses of two populations (Mareth and Gannouch) were conducted in order to study the effect of salinity and gamma radiation (350 Gy) interaction on two populations of this species. It has been shown that the two irradiated populations of Medicago sativa are fairly tolerant to salt at growth phase compared to the non-irradiated. Exposure to gamma irradiation (350 Gy), alone or in combination with salt stress, increased significantly (p<0.001) shoot number, stem height and chlorophyll b pigment especially for the Gannouch population, while no change occurred for the Mareth population. The presence of salt to 9g/l affected significantly the root biomass and induced a reduction of shoot development of both control and irradiated alfalfa populations. For all treatments, plants of two populations remained able to produce and to allocate dry matter to the different organs. The survey of Na⁺ / K⁺ ratio showed that the growth of the aerial organs of two non-irradiated populations was at least determined by a selectivity in favour of the K+ ions (r² = 0.97 and r² = 0.59 for Mareth and Gannouch irradiated populations, respectively). However, the rather weak correlation detected for the irradiated populations, particularly for the irradiated Gannouch, seems to be the consequence of the effect of irradiation that improved potassium availability, essential element for growth and development. Results also showed that the two irradiated populations, especially the Mareth, accumulated Na⁺ ions in its photosynthetic organs. This accumulation was associated with an improvement of foliar water content at a level of salinity arrounding 5g/l. Such a mechanism reflects probably an inclusive behaviour of the plants and a good aptitude to use the dominant ions (Na⁺) for the osmotic adjustment. However, the non-irradiated populations are unable to adjust their internal osmotic potential. Consequently, irradiated plants have probably adapted to the osmotic stress by either closing their stomata or increasing the osmotic pressure of the leaf cells.     

A possible configuration of H 5 + cluster

On the basis of our previous work, a configuration of H ₅ ⁺ has been presented that is a square center structure, and the energy for the structure of H ₅ ⁺ has been obtained by IACQM. The result showed that there is an extreme energy E_e: −2.45981 [2 Ry] atR = 2.50a ₀. It indicates that the square center structure of H ₅ ⁺ system has the certain stability, which is a possible configuration of H ₅ ⁺ .     

The seasonal variations of δ~(18)O , Cl~- , Na~+ , NO_3~- and Ca~(2+) in the snow and firn recovered from Princess Elizabeth Land, Antarctica

Snow and firn samples recovered from two snow pits (2.5 and 4.5m deep) and one 50-m firn core along the route of the 1996/1997 Chinese First Antarctic Inland Traverse Expedition in Princess Elizabeth Land, East Antarctica, have been measured for chemical composition and oxygen isotope ratio. In the two snow pits, the variations of NO3- are partly in phase with that of δ18O, while the variations of Cl~ and Na+ are in inverse phase with that of δ18O. The variations of CI- , Na+ , NO3- and δ18O show obvious seasonal variations and annual stratag-raphy. However, with the depth increasing, the seasonal variations of δ18O are gradually smoothed below 3 m (corresponding to about 10-year mass accumulation) in depth while the seasonal variations of Cl- , Na+ and NO3- are kept fairly well in the whole profile of the 50-m firn core (corresponding to about 250-year mass accumulation). The results provide a useful tool for dating the snow stratum in this region. On the contrary, no obvious seasonal variations of Ca2 + are found in the profiles.     

Na+-permeable channels of human sperm membrane reassembled into giant liposome

Previous data showed that a Na⁺-transmembrane flux was accompanied with acrosome reaction of sperm. However, the electrophysiological recording and characterization of Na⁺ current in human sperm membrane have not been yet reported. In the present investigation, membrane proteins extracted from human sperms were reassembled into liposome bilayer, and then the liposomes were fused by dehydration-rehydration into giant liposomes with the diameter of more than 10 ώm. By patch clamping the giant liposomes two kinds of single channel currents were recorded in a NaCl solution system. Both of them were Na⁺-carried, TTX-sensitive and strongly rectifying, but with different unit conductance and open probability. Moreover, bursting activity and channel-substates as well as two open time constants were observed in the larger channel.     

Molecular characterization of a K+ channel blocker in the scorpionButhus martensii Karsch

K⁺ channel blockers of scorpion venoms are of important value in studying pharmacology and physiology of specific K⁺ channel of cells. Based on the amino acid sequences of BmP01 previously characterized as a small-conductance Ca²⁺-activated K⁺ channel blocker, two “back to back” degenarate primers have been designed and synthesized for inverse PCR strategy, its full-length cDNA has been cloned from the venom gland of the Chinese scorpionButhus martensii. The cDNA is composed of 3 parts: 5′ UTR, ORF and 3′ UTR. The flanking sequence of translation initiation codon ATG is AAAATGA, which is highly conserved in scorpion Na⁺ channel toxin and protozoan genes, suggesting that these genes may have followed a common mechanism for translation initiation. The 3′ UTR contains poly(A) signal AATAAA. The open reading frame encodes a precursor of 57 residues with a signal peptide of 28 residues and a mature peptide of 29 residues. The signal peptide is rich in hydrophobic amino acid residues and its length is significantly different from that of the determined scorpion Na⁺ channel toxin. The deduced amino acid sequence of mature peptide is completely consistent with BmP01 previously determined by primary structure analysis.     

Measurement of the absorption spectrum of H2O+ in the visible region

Together with the 74 lines belonging to (0,9,0)- (0,0,0) band, the high-resolution absorption spectrum of H₂O⁺ A²A₁-X²B₁ system was observed in the visible region of 16680 — 17300 cm^-1 using optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy for the first time, which verifies the high sensitivity and high signal to noise ratio (S/N) of this technique.     

Nitric oxide suppresses stomatal opening by inhibiting inward-rectifying K<Stack><Subscript>in</Subscript><Superscript>+</Superscript></Stack> channels in <Emphasis Type="Italic">Arabidopsis</Emphasis> guard cells

We explore nitric oxide （NO） effect on K^＋in, channels in Arabidopsis guard cells. We observed NO inhibited K^＋in, currents when Ca^2＋ chelator EGTA （Ethylene glycol-bis（2-aminoethylether）-N,N,N′,N;tetraacetic acid） was not added in the pipette solution; K^＋in currents were not sensitive to NO when cytosolic Ca^2＋ was chelated by EGTA. NO inhibited the Arabidopsis stomatal opening, but when EGTA was added in the bath solution, inhibition effect of NO on stomatal opening vanished. Thus, it implies that NO elevates cytosolic Ca^2＋ by activating plasma membrane Ca^2＋ channels firstly, then inactivates K^＋in, chartnels, resulting in stomatal opening suppressed subsequently.     

NLi4+超碱团簇的结构及储氢性能的理论研究

采用密度泛函理论（B3LYP）方法,在6-311++G（d,p）基组水平上对NLi₄超碱团簇和NLi₄⁺超碱离子团簇的几何结构和稳定性等物理化学性质进行理论计算,进而研究NLi₄团簇和NLi₄⁺团簇的储氢性能。结果表明：NLi₄团簇和NLi₄⁺团簇结构稳定性均比较高,但是通过理论计算表明NLi₄团簇不能有效吸附氢分子,而NLi₄⁺团簇在吸附氢分子过程中不仅结构稳定,而且NLi₄⁺团簇中的每一个锂原子均可有效吸附3个氢分子,氢分子平均吸附能为1.517~2.931 kCal/mol,储氢质量分数达36.67 wt%,合适的吸附能和较高储氢容量表明NLi₄⁺团簇可有望成为良好的储氢材料。     

VUV threshold photoelectron spectroscopy of the C2H3Cl molecule

The threshold photoelectron spectrum of the C₂H₃Cl molecule is studied by using synchrotron radiation light source and supersonic molecular beam. The vertical ionization potentials of different orbital electrons and some vibrational structures are obtained. The observed Rydberg autoionization peaks are assigned by A²A¹ state of C₂H₃Cl₊.     

黑鲷NKCC1分子特征及其对急性盐度胁迫的表达响应

为了解黑鲷(Acanthopagrus schlegelii)在盐度胁迫过程中的适应机制,本研究利用基因扩增、聚类分析、荧光定量PCR等技术对NKCC1基因进行生物信息学分析以及在不同组织中的表达特征研究,并探讨其在急性盐度胁迫下的表达机制.结果表明NKCC1基因的开放阅读框(Open Reading Frame,OR...     

Effect of MTEC1 on the functional expression of TCRaβ+ 3G11− 6C10− CD4+ CD8− thymocyte subset

A murine CD4⁺ thymocyte subset with phenotype of TCRαβ⁺ 3G11⁻ 6C10⁻ CD4⁺ CD8⁻ CD69^+/- HSA^med/lo contains the cells in relatively functional matured status. The functional property of the cells in this subset is characterized by the unique pattern of cytokine production at transitional stage from Th0 to Th2 type with the latter being the dominant type. After being co-cultured with murine thymic medullary epithelial cell line (MTEC1) cells, a murine thymic medullary type epithelial cell line, the TCRαβ⁺ 3G11⁻ 6C10⁻ CD4⁺ CD8⁻ CD69^+/- HSA^med/lo thymocytes, has exhibited significantly higher levels of proliferation capability and IL-6 production, whereas the production of IL-4 and IL-10 is suppressed after co-culturing with MTECl. By contrast, MTECl could not induce thymocytes to secrete Thl type of cytokines. The results suggest that MTECl can regulate functional status of this thymocyte subset and induce them to develop into a specialized Th2 subset.     

Phenotypic analysis of the medullary-type CD4−CD8+ thymocytes in mice

Phenotypic analysis of the medullary-type CD4 CD8⁺ (CD8SP) thymocytes has revealed phenotypic heterogeneity within this cell population. The phenotype of mature peripheral CDS⁺T cells is TCRαβ⁺CD3⁺Qa-2⁺HSA 3G11⁻6C10, whereas in the medullary-type CD8SP thymocytes, 20% are Qa-2⁺; 33%, HAS; 30%, 3G11; and 70% are 6C10. The disparate expression patterns of these four cell surface markers suggest that medullary-type CD8SP thymocytes may undergo phenotypic maturation process. According to the distribution of these four cell surface markers, six subgroups of CD8SP thymocytes have been identified. The precursor-progeny relationship along with developmental pathway is postulated as follows: 6C10⁺HSA⁺3G11 Qa-2→ 6C10⁺HSA⁺ 3G11⁺Qa-2 → 6C10 HSA⁺3G11⁺Qa-2 → 6C10⁻HSA⁻3G11⁺Qa-2 → 6C10⁻HSA⁻3G11 Qa-2 → 6C10⁻HA S 3G11 Qa-2⁺, the cells in the last subgroup exit the thymus and home into periphery.     

多复变中Dp和H∝及βp空间的一些关系

在 Cⁿ中的单位球上, 讨论了Dirichlet 型空间D_p和广义Bloch空间β^q的相互包含关系以及D_p 和Hardy空间H^∝之间的点乘子,根据 p 的一些不同情形对M(H^∝, D_p ) 和 M( D_p , H^∝) 进行了刻划.