7份不同产地野生甜茶FTIR指纹图谱及其甜茶苷含量比较分析

本研究运用傅里叶变换红外光谱法,采集7份不同产地甜茶叶片的FTIR图谱,结合相关性系数和二阶导数方法对其红外光谱特征进行指认,并比较各供试甜茶的红外指纹图谱及甜茶苷含量间差异。研究结果表明,依据不同产地甜茶红外指纹图谱特征,可以将其归结为3大类Ⅰ类包括:金秀、荔浦、平南、象州及永福等地的甜茶,相关系数在0.992～0.999间;Ⅱ类包括第Ⅰ类型以外的广西其它采集地区的甜茶,相关性系数主要集中在0.984～0.990之间;Ⅲ类包括广东分布区,该区甜茶与广西分布区甜茶的相关系数均在0.986以下。供试甜茶与甜茶苷标准品的光谱特征比较结果表明,不同产地甜茶甜茶苷含量有较大差异。其中,广西金秀和广西平南产的甜茶叶片中甜茶苷含量最高,广西岑溪产的甜茶叶片中甜茶苷含量最低。所以,运用FTIR技术可以对不同产地甜茶进行分析并快速鉴别出不同产地甜茶中甜茶苷含量差异。本研究结果对广西地区甜茶的引种驯化和合理开发利用有一定指导意义。     

<Emphasis Type="Italic">In vivo</Emphasis> fluorescence observation of parasporal inclusion formation in <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis>

A recombinant gene expressing a Cry1Ac-GFP fusion protein with a molecular mass of approximately 160 kD was constructed to investigate the expression of cry1Ac, the localization of its gene product Cry1Ac, and its role in crystal development in Bacillus thuringiensis. The cry1Ac-gfp fusion gene under the control of the cry1Ac promoter was cloned into the plasmid pHT304, and this construct was designated pHTcry1Ac-gfp. pHTcry1Ac-gfp was transformed into the crystal-negative strain, HD-73 cry⁻, and the resulting strain was named HD-73⁻(pHTcry1Ac-gfp). The gfp gene was then inserted into the large HD-73 endogenous plasmid pHT73 and fused with the 3′ terminal of the cry1Ac gene by homologous recombination, yielding HD-73Φ(cry1Ac-gfp)3534. Laser confocal microscopy and Western blot analyses showed for the first time that the Cry1Ac-GFP fusion proteins in both HD-73⁻(pHTcry1Ac-gfp) and HD-73Φ(cry1Ac-gfp)3534 were produced during asymmetric septum formation. Surprisingly, the Cry1Ac-GFP fusion protein showed polarity and was located near the septa in both strains. There was no significant difference between Cry1Ac-GFP and Cry1Ac in their toxicity to Plutella xylostella larvae.     

Efficient production of omega-3 fatty acid desaturase (sFat-1)-transgenic pigs by somatic cell nuclear transfer

Omega-3(ω-3) fatty acid desaturase transgenic pigs may improve carcass fatty acid composition. The use of transgenic pigs is also an excellent large animal model for studying the role of ω-3 fatty acids in the prevention and treatment of coronary heart disease and cancer. Transgenic pigs carrying synthesized fatty acid desaturase-1 gene (sFat-1) from Caenorhabditis briggsae by somatic cell nuclear transfer (SCNT) were produced for the first time in China. Porcine fetal fibroblast cells were transfected with a sFat-1 expression cassette by the liposome-mediated method. Transgenic embryos were reconstructed by nuclear transfer of positive cells into enucleated in vitro matured oocytes. A total of 1889 reconstructed embryos were transferred into 10 naturally cycling gilts. Nine early pregnancies were established, 7 of which went to term. Twenty-one piglets were born. The cloning efficiency was 1.1% (born piglets/transferred embryos). The integration of the sFat-1 gene was confirmed in 15 live cloned piglets by PCR and Southern blot except for 2 piglets. Expression of the sFat-1 gene in 12 of 13 piglets was detected with RT-PCR. The data demonstrates that an efficient system for sFat-1 transgenic cloned pigs was developed, which led to the successful production of piglets expressing the sFat-1 gene.     

αB-crystallin is mutant B-RAF regulated and contributes to cyclin D1 turnover in melanocytic cells

The serine/threonine kinase, B-RAF, is frequently mutated in melanoma and is required for cell proliferation. Proteasomal turnover of cyclins and cyclin-dependent kinase inhibitors via E3 ubiquitin ligases regulates cell cycle progression. We previously showed that B-RAF regulates Cks1, a co-factor for the F-box protein Skp2. Recently, a second F-box protein cofactor was identified, αB-crystallin, that binds Fbx4 and promotes cyclin D1 degradation. Here, we demonstrate that αB-crystallin is down-regulated in mutant B-RAF melanoma cells compared to melanocytes in a B-RAF and MEK-dependent manner. In a subset of lines, MEK inhibition was sufficient to up-regulate αB-crystallin protein levels; whereas in other lines combined MEK and proteasome inhibition was required. αB-crystallin knockdown partially stabilized cyclin D1 in melanocytes. Expression of αB-crystallin in mutant B-RAF melanoma cells did not promote cyclin D1 turnover under normal conditions, but did enhance turnover following etoposide-induced DNA damage. Together, these data show that αB-crystallin is highly expressed in melanocytes contributing, in part, to cyclin D1 turnover. Furthermore, αB-crystallin is down-regulated in a B-RAF-dependent manner in melanoma cells and its re-expression regulates cyclin D1 turnover after DNA damage.     

Drought-deciduous behavior reduces nutrient losses from temperate deciduous trees under severe drought

Nutrient resorption from senescing leaves is an important mechanism of nutrient conservation in temperate deciduous forests. Resorption, however, may be curtailed by climatic events that cause rapid leaf death, such as severe drought, which has been projected to double by the year 2100 in the eastern United States. During a record drought in the southeastern US, we studied 18 common temperate winter-deciduous trees and shrubs to understand how extreme drought affects nutrient resorption of the macronutrients N, P, K, and Ca. Four species exhibited drought-induced leaf senescence and maintained higher leaf water potentials than the remaining 14 species (here called drought-evergreen species). This strategy prevented extensive leaf desiccation during the drought and successfully averted large nutrient losses caused by leaf desiccation. These four drought-deciduous species were also able to resorb N, P, and K from drought-senesced leaves, whereas drought-evergreen species did not resorb any nutrients from leaves lost to desiccation during the drought. For Oxydendrum arboreum, the species most severely affected by the drought, our results indicate that trees lost 50% more N and P due to desiccation than would have been lost from fall senescence alone. For all drought-deciduous species, resorption of N and P in fall-senesced leaves was highly proficient, whereas resorption was incomplete for drought-evergreen species. The lower seasonal nutrient losses of drought-deciduous species may give them a competitive advantage over drought-evergreen species in the years following the drought, thereby impacting species composition in temperate deciduous forests in the future.     

Protective effect of supplemental anthocyanins on Arabidopsis leaves under high light

Ten anthocyanin components have been detected in roots of purple sweet potato (Ipomoea batatas Lam.) by high‐performance liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry. All the anthocyanins were exclusively cyanidins or peonidin 3‐sophoroside‐5‐glucosides and their acylated derivatives. The total anthocyanin content in purple sweet potato powder obtained by solid‐phase extraction was 66 mg g^?1. A strong capacity of purple sweet potato anthocyanins (PSPA) to scavenge reactive oxygen species (superoxide, hydroxyl radical) and the stable 1,1‐diphenyl‐2‐picrylhydrazyl organic free radical was found in vitro using the electron spin resonance technique. To determine the functional roles of anthocyanins in leaves in vivo, for the first time, supplemental anthocyanins were infiltrated into leaves of Arabidopsis thaliana double mutant of the ecotype Landsberg erecta (tt3tt4) deficient in anthocyanin biosynthesis. Chlorophyll fluorescence imaging showed that anthocyanins significantly ameliorated the inactivation of photosystems II during prolonged high‐light (1300 µmol m^?2 s^?1) exposure. Comet assay of DNA revealed an obvious role of supplemental PSPA in alleviating DNA damage by high light in leaves. Our results suggest that anthocyanins could function in vitro and in vivo to alleviate the direct or indirect oxidative damage of the photosynthetic apparatus and DNA in plants caused by high‐light stress.     

Responses of soil chemical and biological properties to nitrogen addition in a Dahurian larch plantation in Northeast China

Soil microbial properties play a key role in belowground ecosystem functioning, but are not well understood in forest ecosystems under nitrogen (N) enrichment. In this study, soil samples from 0–10 cm and 10–20 cm layers were collected from a Dahurian larch (Larix gmelinii Rupr.) plantation in Northeast China after six consecutive years of N addition to examine changes in soil pH, nutrient concentrations, and microbial biomass and activities. Nitrogen addition significantly decreased soil pH and total phosphorus, but had little effect on soil total organic carbon (TOC) and total N (TN) concentrations. The NO ₃ ^? -N concentrations in the two soil layers under N addition were significantly higher than that in the control, while NH ₄ ⁺ -N concentrations were not different. After six years of N addition, potential net N mineralization and nitrification rates were dramatically increased. Nitrogen addition decreased microbial biomass C (MBC) and N (MBN), and MBC/TOC and MBN/TN in the 0–10 cm soil layer, but MBC/MBN was increased by 67% in the 0–10 cm soil layer. Soil basal respiration, microbial metabolic quotient (qCO₂), and β-glucosidase, urease, acid phosphomonoesterase and nitrate reductase activities in the two soil layers showed little change after six years of N addition. However, soil protease and dehydrogenase activities in the 0–10 cm layer were 41% and 54% lower in the N addition treatment than in the control, respectively. Collectively, our results suggest that in the mid-term N addition leads to a decline in soil quality in larch plantations, and that different soil enzymes show differentiated responses to N addition.     

HO-1 modified mesenchymal stem cells modulate MMPs/TIMPs system and adverse remodeling in infarcted myocardium

The present study was to determine the effects of the heme oxygenase-1 (HO-1) modified mesenchymal stem cells (MSCs) transplantation into acute MI hearts on normalizing the ratio of MMPs/TIMPs and remodeling in infarcted myocardium. HO-1 was transfected into cultured MSCs using an adenoviral vector. 1 × 10⁶ Ad-HO-1-transfected MSCs (HO-1-MSCs) or Ad-Null-transfected MSCs (Null-MSCs) or PBS was respectively injected into rat hearts 1 h intramyocardially after myocardial infarction. The cardiac performance was significantly improved and left ventricular dilatation was significantly attenuated in HO-1-MSCs transplanted hearts. Moreover, a significant increase in microvessel density was observed in HO-1-MSCs transplanted hearts. TIMP2,3 expression in HO-1-MSCs transplanted hearts was significantly increased, and MMP2,9 expression in HO-1-MSCs transplanted hearts was significantly lower than Null-MSCs transplanted and PBS-treated hearts. TIMP1 expression did not vary significantly. Null-MSCs transplantation did not decrease the expression of MMP2,9 significantly compared with PBS-treated hearts. The ratio of TIMP2 to MMP2, and TIMP3 to MMP9 in cell-grafted hearts was increased significantly. HO-1-MSCs transplantation normalize the ratio of MMPs/TIMPs, contributing to the reversion of myocardial extracellular remodeling.     

Fine mapping a QTL qCTB7 for cold tolerance at the booting stage on rice chromosome 7 using a near-isogenic line

Low temperature at the booting stage is a serious abiotic stress in rice, and cold tolerance is a complex trait controlled by many quantitative trait loci (QTL). A QTL for cold tolerance at the booting stage in cold-tolerant near-isogenic rice line ZL1929-4 was analyzed. A total of 647 simple sequence repeat (SSR) markers distributed across 12 chromosomes were used to survey for polymorphisms between ZL1929-4 and the cold-sensitive japonica cultivar Towada, and nine were polymorphic. Single marker analysis revealed that markers on chromosome 7 were associated with cold tolerance. By interval mapping using an F₂ population from ZL1929-4 × Towada, a QTL for cold tolerance was detected on the long arm of chromosome 7. The QTL explained 9 and 21% of the phenotypic variances in the F₂ and F₃ generations, respectively. Recombinant plants were screened for two flanking markers, RM182 and RM1132, in an F₂ population with 2,810 plants. Two-step substitution mapping suggested that the QTL was located in a 92-kb interval between markers RI02905 and RM21862. This interval was present in BAC clone AP003804. We designated the QTL as qCTB7 (quantitative trait locus for cold tolerance at the booting stage on chromosome 7), and identified 12 putative candidate genes.