A volatile producing endophytic Bacillus siamensis YC7012 promotes root development independent on auxin or ethylene/jasmonic acid pathway

Plant and Soil - In many mixed grass-shrub ecosystems, increased shrub biomass tends to promote overall carbon storage, but the distribution of carbon pools may be complicated by disturbances such...     

Properties of Hexadecaprenyl Monophosphate/Dioleoylphosphatidylcholine Vesicular Lipid Bilayers

In our study we investigated hemispherical phospholipid bilayer membranes and phospholipid vesicles made from hexadecaprenyl monophosphate (C₈₀-P), dioleoylphosphatidylocholine (DOPC) and their mixtures by voltammetric and transmission electron microscopy (TEM) techniques. The current-voltage characteristics, the membrane conductance-temperature relationships and the membrane breakdown voltage have been measured for different mixtures of C₈₀-P/DOPC. The membrane hydrophobic thickness and the activation energy of ion migration across the membrane have been determined. Hexadecaprenyl monophosphate decreased in comparison with DOPC bilayers, the membrane conductance, increased the activation energy and the membrane breakdown voltage for the various value of C₈₀-P/DOPC mole ratio, respectively. The TEM micrographs of C₈₀-P, DOPC and C₈₀-P/DOPC lipid vesicles showed several characteristic structures, which have been described. The data indicate that hexadecaprenyl monophosphate modulates the surface curvature of the membranes by the formation of aggregates in liquid-crystalline phospholipid membranes. We suggest that the dynamics and conformation of hexadecaprenyl monophosphate in membranes depend on the transmembrane electrical potential. The electron micrographs indicate that polyprenyl monophosphates with single isoprenyl chains form lipid vesicular bilayers. The thickness of the bilayer, evaluated from the micrographs, was 11 ± 1 nm. This property creates possibility of forming primitive bilayer lipid membranes by long single-chain polyprenyl phosphates in abiotic conditions. It can be the next step in understanding the origin of protocells. Received: 10 January 2000/Revised: 7 June 2000     

End-binding protein 1 (EB1) up-regulation is an early event in colorectal carcinogenesis

End-binding protein (EB1) is a microtubule protein that binds to the tumor suppressor adenomatous polyposis coli (APC). While EB1 is implicated as a potential oncogene, its role in cancer progression is unknown. Therefore, we analyzed EB1/APC expression at the earliest stages of colorectal carcinogenesis and in the uninvolved mucosa (“field effect”) of human and animal tissue. We also performed siRNA-knockdown in colon cancer cell lines. EB1 is up-regulated in early and field carcinogenesis in the colon, and the cellular/nano-architectural effect of EB1 knockdown depended on the genetic context. Thus, dysregulation of EB1 is an important early event in colon carcinogenesis.     

Identification of a recurrent insertion mutation in the LDLR gene in a Pakistani family with autosomal dominant hypercholesterolemia

Familial Hypercholesterolemia (FH) results in elevated levels of blood lipids including total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) with normal triglycerides (TG). This disease is one of the major contributors towards an early onset of coronary heart disease (CHD). The aim of the present study was to identify the genes responsible for causing FH in Pakistani population, for this purpose a large consanguineous FH family was selected for genetic analysis. Serum lipid levels, including TC, TG, LDL-C and high density lipoprotein cholesterol (HDL-C), were determined in patients and healthy controls. In order to find the causative mutation in this family, direct sequencing of the low density lipoprotein receptor (LDLR) gene was performed. In addition the part of the Apolipoprotein-B (APOB) gene containing the mutations R3500Q and R3500W was also sequenced. Affected individuals of the family were found to have raised TC and LDL-C levels. Sequencing revealed an insertion mutation (c.2416_2417InsG) in exon 17 of the LDLR gene in all the affected individuals of the family. Common FH causing APOB mutations were not present in this family. Heterozygous individuals had TC levels ranging from ~300–500 mg/dl and the only homozygous individual with typical xanthomas had TC levels exceeding 900 mg/dl. This is the first report of a known LDLR gene mutation causing FH in the Pakistani population. Despite a large heterogeneity of LDLR mutations there are still some common mutations which are responsible for FH throughout the world.     

Anti-proliferative effects of γ-tocotrienol on mammary tumour cells are associated with suppression of cell cycle progression

Objectives:  Previous studies have shown that γ-tocotrienol induces potent anti-proliferative effects on +SA mammary tumour cells in culture; here, investigations have been conducted to determine its effects on intracellular signalling proteins involved in regulating cell cycle progression.
Materials and methods:  +SA cells were maintained in mitogen-free defined media containing 0 or 4 μ m γ-tocotrienol, for 48 h to synchronize cell cycle in G₀ phase, and then they were exposed to 100 ng/ml EGF to initiate cell cycle progression. Whole cell lysates were collected at various time points from each treatment group and were prepared for Western blot analysis.
Results and conclusions:  Treatment with 4 μ m γ-tocotrienol significantly inhibited +SA cell proliferation over a 4-day culture period. Moreover, this treatment resulted in a relatively large reduction in cyclin D1, cyclin dependent kinase (CDK)4, CDK2 and CDK6 levels, between 4 and 24 h after EGF exposure. Tocotrienol treatment also resulted in a relatively large increase in CDK inhibitor (CKI) p27, prior to and after EGF exposure, but had little effect on levels of CKIs, p21 and p15. Tocotrienol treatment also induced a large relative reduction in retinoblastoma (Rb) protein phosphorylation at ser780 and ser807/811. These findings strongly suggest that anti-proliferative effects of γ-tocotrienol are associated with reduction in cell cycle progression from G₁ to S, as evidenced by increased p27 levels, and a corresponding decrease in cyclin D1, CDK2, CDK4, CDK6 and phosphorylated Rb levels.     

Molecular docking analysis of HER-2 inhibitor from the ZINC database as anticancer agents

The human epidermal growth factor (HER2) is a transmembrane receptor that is highly expressed in breast cancer and in different other cancers. Therefore, it is of interest to identify the new HER2 inhibitors from a selected 300 compounds in the ZINC database. The top two hit compounds (ZINC000014780728 (-11.0 kcal/mol) and ZINC000014762512 (-10.8 kcal/mol)) showed a high affinity with HER2 relative to the reference compound (lapatinib (-10.2 kcal/mol)) for further consideration.     

Vitamin D receptor is not required for the rapid actions of 1,25-dihydroxyvitamin D3 to increase intracellular calcium and activate protein kinase C in mouse osteoblasts

The rapid, non-genomic actions of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] have been well described, however, the role of the nuclear vitamin D receptor (VDR) in this pathway remains unclear. To address this question, we used VDR(+/+) and VDR(-/-) osteoblasts isolated from wild-type and VDR null mice to study the increase in intracellular calcium ([Ca(2+)](i)) and activation of protein kinase C (PKC) induced by 1,25(OH)(2)D(3). Within 1 min of 1,25(OH)(2)D(3) (100 nM) treatment, an increase of 58 and 53 nM in [Ca(2+)](i) (n = 3) was detected in VDR(+/+) and VDR(-/-) cells, respectively. By 5 min, 1,25(OH)(2)D(3) caused a 2.1- and 1.9-fold increase (n = 6) in the phosphorylation of PKC substrate peptide acetylated-MBP(4-14) in VDR(+/+) and VDR(-/-) osteoblasts. The 1,25(OH)(2)D(3)-induced phosphorylation was abolished by GF109203X, a general PKC inhibitor, in both cell types, confirming that the secosteroid induced PKC activity. Moreover, 1,25(OH)(2)D(3) treatment resulted in the same degree of translocation of PKC-alpha and PKC-delta, but not of PKC-zeta, from cytosol to plasma membrane in both VDR(+/+) and VDR(-/-) cells. These experiments demonstrate that the 1,25(OH)(2)D(3)-induced rapid increases in [Ca(2+)](i) and PKC activity are neither mediated by, nor dependent upon, a functional nuclear VDR in mouse osteoblasts. Thus, VDR is not essential for these rapid actions of 1,25(OH)(2)D(3) in osteoblasts.     

休哈塔假丝酵母发酵木糖制乙醇过程研究

木质纤维素原料水解产物的主要成分是葡萄糖和木糖,其中葡萄糖很容易发酵,致使木糖成为木质纤维素发酵的关键,休哈塔假丝酵母(Candida shehatae)1766是自然界木糖发酵性能较好的天然酵母之一。研究了发酵温度、发酵时间、接种量、初始pH值、摇床转速等因素对休哈塔假丝酵母1766发酵木糖生产乙醇的影响,由正交试验初步确定了休哈塔假丝酵母发酵木糖制乙醇工艺的适宜条件为好氧条件,发酵时间为2d,发酵温度为28℃,摇床转速为150r/min,初始pH值为5,此时乙醇收率最高可达68.62%。     

岩溶石漠化区不同植被恢复模式土壤无机磷形态特征及影响因素

为分析岩溶石漠化区不同植被恢复模式土壤无机磷的形态特征,评价植被恢复的土壤供磷潜力,阐明有机碳及钙素在无机磷形态转化中的作用,选取研究区内8种有代表性的样地,采用蒋柏藩无机磷分级方法对土壤无机磷形态特征及影响因素进行研究。结果表明:研究区土壤全磷与速效磷含量分别在0.25—1.35 g/kg、1.05—53.01 mg/kg范围,无机磷总量在123.94—934.61 mg/kg,耕地与退耕地以及各退耕地之间全磷、速效磷、各形态无机磷含量水平差异明显,各退耕地磷素含量水平介于耕地与次生马尾松林地之间,退耕地中桃林地、花椒林地磷素含量水平较高、樟树林地、柳杉林地、撂荒草地次之、撂荒灌丛地较低。各样地土壤无机磷占全磷比例在51.2%—72.4%,不同形态的无机磷含量表现为O-PFe-PCa-PAl-P,其中Ca2-P、Al-P对速效磷的贡献率大,Fe-P、Ca8-P贡献较小,O-P、Ca10-P献率最小。不同活性土壤有机碳与不同形态钙素对各形态无机磷在总无机磷中比例的影响较大,p H、容重、粘粒含量、含水量等其它理化性质影响较小。     

The effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of Suaeda salsa under saline conditions

Suaeda salsa, a leaf succulent shrub in the family Chenopodiaceae, is one of the most important halophytes in China. Suaeda salsa produces dimorphic seeds (soft brown seeds and hard black seeds). Seeds of S. salsa were collected from the coastal salt flats near Huanghua City, China. Experiments were conducted to determine the salinity-alleviating effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of S. salsa. Brown seeds had a higher germination rate than black seeds in all experiments. Black seeds were more sensitive to salt in the absence of light in comparison to brown seeds. Brown seeds absorbed water more quickly in comparison to black seeds and were found to be more tolerant of salt stress. Our results showed that 1-aminocyclopropane-1-carboxylate (ACC, the immediate precursor of ethylene), nitrite, GA₄ and BA improved seed germination in the presence of salt. However, nitrate, GA₁, GA₃ failed to alleviate salt stress. ABA inhibited seed germination and seedling growth. Possible mechanisms involved in the alleviation of salt stress in S. salsa seeds and the ecological adaptation of the seeds to the environment are discussed.