Effect of internal deletion of Myosin Ⅱ on growth and development of Dictyostelium discoideum

Four deletion mutant Dictyostelium myosin Ⅱ heavy chain genes, MyΔ824-941 (Δ1/ 3S2), MyΔ934-1454 (ΔS2), MyΔ934-1194 (ΔS2-1) and MyΔ1157-1454 (ΔS2-2), were transformed by standard electroporation into mhcA- cells (T-null), a mutant Dictyostelium cell devoid of endogenous myosin Ⅱ heavy chain gene. The growth, development and formation of fruiting bodies of cells expressing those mutant myosin Ⅱ s under suspension culture were investigated by comparison with the wild type cell. The results indicate that internal deletion of myosin Ⅱ affects the growth and development of Dictyostelium. Furthermore, the longer the length of deletion , the more serious the defect in phenotype.     

A class of complex quasi-Orlicz spaces and their analytic RN property

LetX be a complex quasi-Banach space and Φ:[0,∞)→[0,∞) an increasing convex function with Φ(0)=0, and Φ∈Δ₂. ThenL _Φ ^* (X) is a quasi-Banach space with continuous quasi-norm andL _Φ ^* (X) has the ARNP if and only ifX does. Supported by the National Natural Science Foundation of China Liu Peide: born in 1943, Professor     

Deletion analysis of oligomycin PKS genes （olmA） in Streptomyces arermitilis

Gene deletion vector pXL05(pKC1139::△olmA1 △olmA4) was used to disrupt oligomycin PKS encoding genes (olmA ) in Streptomyces avermitilis CZ8-73, the producer of anthelmintic avermectins B and the cell growth inhibitor oligomycin, olmA gene cluster in the chromosome was displaced by deletion allele on the plasmid via double crossover. Four of disruptants were confirmed by Southern blotting. Shaking flask experiments and HPLC analyses showed that the four mutants no longer produced the toxic oligomycin, but only made four components of avermectins B, which were avermectin Bla, Blb, B2a, B2b. The yields of avermectins B in these mutants were separately equal to those in CZ8-73. This revealed that olmA genes deletion did not affect the biosynthesis of avermectins. The deletion mutants were proved to be genetically stable, and thus might be promising strains in industrial production of avermectins B.     

The composition and distribution of metal clusters in the MoFe protein from a nifZ deletion strain （DJ 194） of Azotobacter vinelandii

Through the anaerobic chromatography on the columns of DEAE 52, Q-Sepharose and Sephacryl S-200, a nitrogenase MoFe protein (△nifZ Av1) was obtained from a nifZ deleted mutant of Azotobacter vinelandii (stain DJ194).The results of Western blotting after anoxic native electrophoresis and SDS-PAGE showed that △nifZ Av1 was similar to wild type MoFe protein (OP Av1) at the electrophoretic mobility, molecular weight and subunit composition. Furthermore, △nifZ Avl was also similar to OP Av1 at the molybdenum content, EPR signal (g≈4.3, 3.65 and 2.01), and the molar extinction coefficient (△ε) of circular dichroism (CD)at 660 nm region. All of these indicated that, besides having the same α2β2 composition as OP Av1, the △nifZ Av1 also contained equal amount of reductive FeMoco in the spin state of S=3/2 to OP Av1. However, the iron content and substrate (C2H2, H^ and N2)-reduction activity of △nifZ Av1 were 74% and 46%-50% of those of OP Av1, respectively. Furthermore, the △ε at around 450 nm, which reflects P-cluster in Av1, was obviously lower than that of OP Av1. It suggested that the difference between △nifZ Avl and OP Av1 resulted from P-cluster rather than FeMoco, and from the half number of P-cluster in △nifZ Av1, but the composition or redoxstate of P-cluster in △nifZ Av1 were not changed. Thus it could propose that △nifZ Av1 is composed of two different αβsubunit pairs. One is a FeMoco-and P-cluster-containing pair, and the other is a P-cluster-deficient but FeMoco-containing pair. Since the deletion of nifZ gene leads to the deficiency of only one of two P-clusters in a α2β2 tetramer, the assembly of P-cluster may not simply depend on one gene product, and so a possible mechanism of NifZ is supposed here.     

Actin and myosin during pollen germination

Actin and myosin from pollen tubes of Lilium davidii were studied by using immunoblotting, Dot_Blot and myosin Ca 2+_ATPase analysis. On immunoblotting of the total soluble pollen tube proteins, anti_α_actin antibody labelled a polypeptide approximately 43 ku, which is considered to be the actin of lily. The mRNA encoding actin in ungerminated pollen and germinated pollen were both undetectable in our experiments. A myosin exhibited Ca 2+_ATPase activity, with a native molecular weight of 460 ku has been identified by using immunoblotting. A polypeptide of about 205 ku and a polypeptide of about 20 ku were the heavy chain and a set of light chain of the myosin, which can crossreact with anti_skeletal muscle myosin heavy chain monoclonal antibody and anti_skeletal muscle myosin light chain (20 ku) monoclonal antibody, respectively. The Ca 2+_ATPase activities of myosin in crude extracts of germinated pollen were positively related to the growth rates of pollen tubes.     

Effects of antisense CENP-B on the proliferation of HeLa (Tet-off) cells

In order to study the change of the expression of centromere protein B (CENP-B) caused by antisense transfection, proto-eukaryotically expressed fused protein GST-CENP-B (65 ku) was injected into mouse, and a peculiar anti-CENP-B serum MaCenpB was collected. A strain of transfected HeLa Tet-off cell HaCb, which contains antisense CENP-B expressing vector pBI-EGFP-as-CenpB, was prepared. Northern blot and Western blot were used to analyze the repression of internal CENP-B in transfected cells. According to the growth curve, the proliferation of HeLa (Tet-off) is repressed by antisense CENP-B, and the multiplication time is prolonged for 32.81 h. The analysis of flow cytometry revealed that, compared with HeLa (Tet-off), the G₁ cell population of HaCb is increased (ΔG₁= 9%) while S fraction is decreased (ΔS = 11%), but the G₂/M phase is nearly unchanged (ΔG₂/M=3%). In the meanwhile, the mitotic index of HaCb declines greatly compared with that of HeLa (Tet-off). Immunofluorescence showed that the assembling of centromeres in HaCb cell is arrested. These results suggest that a normal expression of CENP-B may be necessary for cell proliferation.     

Functional Imaging of Breast Tissue and Clinical Application

0Introduction Near infrared(NIR)techniquesarebasedonsensitive,quantitativemeasurementsoffunctionalcontrastbe tweenhealthyanddiseasedtissue.Recently,researchersshowgreatinterestinmeasuringfunctionalpropertiesofbreasttis suesuchashemoglobinconcentrationoroxygensaturationbyNIRspectroscopyandNIRimaging[1,2].NIRlightcanpene trateseveralcentimetersintotissuebeforeitisattenuatedbe lowdetection.ThemainintrinsicmechanismsofNIRlightat tenuationintissuearethescatteringduetoindexofrefractionvariatio…     

Purification and characterization of myosin from wheat mitochondria

Myosin was purified from wheat mitochondria using DE-52 anion exchange chromatography and Sephacryl S-300 gel filtration. The molecular weight of its heavy chain is about 210 ku, similar to that of muscle myosin Ⅱ(205 ku), and it could be recognized by the polyclonal antibodies against human skeletal muscle myosin Ⅱ. The ATPase activity of the mitochondrial myosin stimulated by F-actin from chicken muscle is 202.5 nmoles Pi/min·mg. The mitochondrial myosin could be activated by Ca²⁺ and was not inhibited by Ca²⁺ at high concentration. The results demonstrate that the myosin of wheat mitochondria shares some similarities with the skeletal muscle myosin Ⅱ.     

Kinetic studies of the decomposition reaction of adducts of dinuclear Fe(Ⅱ)/O2

Kinetic studies of the decomposition reaction of dinuclear Fe(Ⅱ) adducts [Fe₂(N-Et-HPTB){O₂P(OPh)₂}](Cl- O₄)₂ (1) and [Fe₂(N-Et-HPTB) {O₂P(Ph)₂}] (ClO₄)₂ (2) with O₂ have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe(Ⅱ)/O₂ adducts was first-order in the experimental conditions, and the activation parameters were obtained. ?H^¹ = 85.62 kJ·mol^-1, ?S¹ = 19.43 J·mol^-1·K^-1 for compound (1) and ?H^¹ = 97.97 kJ·mol^-1, ?S^¹ = 55.68 J·mol^-1·K^-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane mono- oxygenase (MMOH).     

Determination of the solubility parameter of cellulose acrylate using inverse gas chromatography

The solubility parameters of cellulose acrylate substituted degree 2.12(CEA) have been calculated from the measured retention data by inverse gas chromatography at various temperatures. The weight frac-tion activity coefficients of the solvents at infinite dilution(Ω1∞),the Flory-Huggins thermodynamic in-teraction parameters between CEA and solvents(χ 1∞2),the excess molar heats of mixing(△H1s),the par-tial molar heats of mixing at infinite dilution(△H1∞),the solubility parameters of solvent(δ1),and the solubility parameters of CEA(δ2),were calculated at various temperatures. The δ2 of the CEA was 17.32,18.00,18.13,18.54,19.39 at 55,60,65,70 and 75℃,respectively.     

A microenvironment,rather than chemical,initiates the cardiomyogenic differentiation of marrow stromal cells

To investigate the potential of cardiomyogenic differentiation of rat hone marrow stromal cells (MSCs), they were exposed to 5-azacytidine treatments (single/repeat) at varying concentrations (3, 5, 10μmol/L) and the fates of the cells were analyzed by immunocytochemistry, Western blot and the reporter gene of enhanced cyan fluorescent protein (ECFP) under the control of ventricular myosin light chain 2 (MLC2v) promoter. MSCs were also cocultured with cardiomyocytes for periods up to 16 days, and the expression of cardiac myosin heavy chain(MHC) and troponin Ⅰ (Tn I) proteins was analyzed. After the induction with 5-azacytidine, neither spontaneously beating ceils nor myotubes were found; MHC and Tn I proteins were also undetectable and no ECFP-positive MSCs were detected. But when cocultured with cardiomyocytes, spontaneously contracting MSCs were observed and cardiac specific proteins could be detected. The results proved that the novel effects of 5-azacytldine on the cardiomyogenic differentiation of MSCs should be questioned and a direct intercellular communication with cardiomyocytes is necessary for MSCs to differentiate into cardiomyocytes.     

JAK3 mediatesc-myc gene expression induced by interleukin-2

C myc gene expression can be rapidly induced by IL 2 through intracellular signal transduction which is triggered by the interaction between IL 2 and its receptor (IL 2R). JAK3 which associates to the intracellular domain of IL_2R γ may play a critical role in this process. To reveal the action of JAK3 in c myc induction, a chimeric receptor gene IL_2R α/γ/Δ NJAK3 is constructed which consists of extracellular domain derived from IL 2R α subunit (IL_2R α), the transmembrane sequence derived from IL_2R γ and the cytoplasmic domain derived from the catalytic domain of JAK3 (Δ NJAK3), and then transfected this chimeric gene into mouse fibroblast cell line L929 β which had been transfected with IL_2R β gene and stably expressed IL_2R β in high level. In the transfectants coexpressing IL_2R β and α/γ/Δ NJAK3, the stimulation of IL_2 could intensively induce c myc gene expression. Because the whole cytoplasmic domain of IL_2R γ which could recruit signaling molecules was replaced by JAK3 and the c myc could be still induced by IL_2 in this situation, the results here gave the direct evidence demonstrating that JAK3 plays an important role in c myc gene expression induced by IL_2.     

秀丽线虫对根际益生菌P13和S3-1传播作用及对植物生长的影响

通过缓慢杀线实验、偏好性实验和共培养毒性实验分析了秀丽线虫(Caenorhabditis elegans)对荧光假单胞菌P13(Pseudomonas fluorescens P13)和解淀粉芽孢杆菌S3-1(Bacillus amyloliquefaciens S3-1)传播的可能性.通过显微观察与平板稀释涂布对秀丽线虫细菌携带作用进行了定性、定量分析,并对细菌—线虫—植物三者交互作用进行初步探究.结果发现,P13和S3-1对秀丽线虫的慢性致死率分别为12.12%和3.00%,每10 s身体弯曲次数分别为4.68和4.33.相对于尿嘧啶缺陷型大肠杆菌(OP50),线虫对P13和S3-1选择系数分别为0.13和0.52,P13、S3-1携带菌量分别为(4.02×103±47)和(9.67×102±22)CFU/条.携细菌线虫将细菌定向传播至植物根际,细菌定殖菌量为105CFU,有效促进植物生长发育.     

Preparation of (R)- and (S)-2-Allyl-1, 3, 2-dinaphtho (α, β) [d.f] dioxaborepin and their reactions with aldehydes

(R)- and(S)-2-Allyl-1,3,2-dinaphtho (α,β) [d.f] dioxaborepin ((R)-2 and(S)-2) have been first prepared by the reaction of(R)-(+)- or(S)-(−)-1, 1′-bi-2-naphthol and triallylborane in THF at room temperature, respectively.(S)-2 and(R)-2 are sensitive to moisture and oxygen in air and disproportionate easily to triallylborane and 1,1′-bi-2 naphthyl bis (1,1′-bi-2-naphtholborate) at ambient temperature. However, THF is a stabilizer for them. The reactions of(R)-2 or(S)-2 and some aliphetic or aromatic aldehydes in CH₂Cl₂ at −78°C for several hours afforded β-alkylenyl alcohols in up to 84.8%ee. Among them, optically active 1-(3, 5-dichlorophenyl)-3-butenol and 1-(2-methoxyphenyl)-3-butenol were first prepared Foundation item: Supported by the National Natural Science Foundation of China (29972033) Biography: Liu Dejun (1973), male, Ph. D, research direction: asymmetric synthesis     

An investigation on supercooling directional solidification process of Cu-Ni single phase alloy

Supercooling directional solidification (SDS) is put fotward by combination of melt supercooling and conventional solidification by application of supercooling inheritance. On the self-designed SDS equipment, SDS of Cu-Ni alloy was achieved successfully The results are as follows f (i) The primary arm spacing is about 30 μm, the growth of secondary arms are strongly suppressed. The primary arm spacing is nearly the same as LMC method (GL=25 K/mm, V=500 pm/s), the primary stems are straight, fine and completed. with an inclination angle of about 5.8° (ii) A semi-quantitative T-T model is brought fotward to describe the dendrite growth rate V vs. undercooling AT The prediction of T-T model agrees well with experimental results. The formation of fine equiaxed dendrites, transition region and dendrite region can be explained successfully by △T-V-x relation of T-T model.     

Spectroscopic investigation of the interaction between human serum albumins and 10-hydroxycamptothecin

The binding reaction between 10-hydroxycamptothecin (10-HCPT) and human serum albumins (HSA) is studied by means of fluorescence spectroscopy, UV-Vis absorption spectrum, 1H NMR spectrum, and molecular simulation. The results indicate that the binding reaction of 10-HCPT and HSA is a single static quenching process, and the binding equilibrium constant for 10-HCPT binding with HSA is estimated K ₀= 4.93×10⁴ L · mol⁻¹ at 25 °C with the molar ratio of 1:1. The distance (r) and energy transfer efficiency (E) between donor (HSA) and acceptor (10-HCPT) are obtained as follows, r =3.51 nm; E =0.27. The enthalpy change (ΔH ^⦵) and entropy change (ΔS ^⦵) are calculated at different temperatures, and the hydrophobic force and shidipole force are the functions in the reaction. The results show that 10-HCPT binds within the subdomain II A of HSA by the hydrophobic force, and the 10-OH and 20-OH of 10-HCPT bind with both residue Leu-238 of HSA and Ala 291 of HSA by hydrogen bonds. Biography: LI Guizhi(1962–), female, Associate professor, research direction: organic analysis.     

The Total Irredundance Numbers on Graphs

This paper discusses the total irredundance relations between the graph G and its clone-contraction graph H, that is, let H be the clone-contraction graph of G and v1,v2,...,vk be all contraction vertices ofH. IfS is a maximal total irredundant set of H such that A = S ∩ {V1,V2,…,Vk} contains as few vertices as possible, then S＇= S-A is the maximal total irredundant set of G. Furthermore, we obtain the bound of the total irredundance A（G） number： irt ≤△（G）/2△（G）＋1 n, which n is the order of graph G, and △（G） is maximum degree in G.