Extracellular DNA plays a key role in deep-sea ecosystem functioning

The ecological role and biogeochemical relevance of extracellular DNA in the oceanic sediments are unknown. Our global estimates indicate that up to 0.45 gigatons of extracellular DNA are present in the top 10 centimeters of deep-sea sediments, representing the largest reservoir of DNA in the world oceans. We demonstrate that extracellular DNA accounts for about one fifth of the total organic phosphorus regeneration and provides almost half of the prokaryotic demand for organic phosphorus. It therefore plays a key role in deep-sea ecosystem functioning on a global scale.     

Alanine: key role in gluconeogenesis

Of 20 amino acids measured, alanine is the principal amino acid released by forearm muscle of man, in accord with its being the principal amino acid extracted by liver for gluconeogenesis. This occurs in both the postabsorptive state and after 4 to 6 weeks of starvation, when total amino acid release is markedly diminished.     

转染抑癌基因PTEN对人乳腺癌ZR-75-1细胞的细胞周期和增殖能力的影响

目的：观察PTEN（phosphatase and tensin homology deleted on chromosome ten，第10号染色体上磷酸酶和张力蛋白同源缺失的基因）对人乳腺癌细胞ZR-75-1细胞增殖和细胞周期的影响。方法；利用脂质体介导法将携带有野生型和突变型PTEN cDNA的真核表达载体pBP—wt—PTEN和pBP—G129R—PTEN导八人乳腺癌ZR-75-1细胞（质粒转染成功后实验分为C—WT—PTEN组、CG129R—PTEN组和未转染质粒组即对照组）后，以RT—PCR、Western blot分析目的基因的表达，并采用MTT法和流式细胞术检测细胞增殖和细胞周期。结果：C—WT—PTEN组、C—G129R—PTEN组细胞PTEN mRNA及PTEN蛋白出现明显的高表达。C—WT—PTEN组细胞生长的抑制率可高达42．7％，与对照组比较．差异有显著性（P〈0．05）。但C—G129R—PTEN组细胞生长的抑制率与对照组比较，差异无显著性（P〉0．05）。流式细胞术显示C—WT—PTEN组细胞周期从G1期到S期已发生抑制。结论：野生型PTEN可依赖其磷酸酶活性抑制肿瘤细胞的增殖,并最终诱导细胞凋亡。     

亨利兜兰茎尖诱导与离体快繁试验

以亨利兜兰的侧芽为试验材料,选择适宜的灭菌方式及筛选出较佳培养基,提高茎尖诱导率。研究基本培养基及激素浓度对继代增殖的影响。结果表明：适合兜兰侧芽的灭菌方式是将75%酒精倒入小烧杯浸泡1 min,无菌水冲洗3次进行消毒处理;倒入0.1%升汞浸泡约5 min,放入0.1%克拉霉素的溶液中5 min,再次放入0.1%升汞浸5 min,用无菌水冲洗5次,然后剥去外层,把5～7 mm茎尖接入培养基中。茎尖诱导培养基以Heller＋6-BA 2 mg/L＋NAA 0.2 mg/L＋C 0.5在继代培养中,试管苗在培养基1/2 MS＋6-BA 0.2 mg/L｜＋NAA 2 mg/L＋10%yz＋C 2中,丛生芽增殖为佳,增殖倍数为3.50。壮苗生根以1/2 MS＋NAA 1＋10%土豆汁＋C 2为好。     

O-甲基芒籽碱对人肿瘤GLC-82、HL60细胞抑制的影响

目的观察O-甲基芒籽碱抗肿瘤的效果。方法以MTT法观察不同浓度O-甲基芒籽碱对人肿瘤GLC-82、HL60细胞抑制的影响。结果10、100和1 000μmol/L O-甲基芒籽碱能抑制GLC-82细胞的增殖,其D值与对照组比较,差异均有统计学意义(P<0.01);0.1、1、10、100和1 000μmol/L O-甲基芒籽碱能抑制HL60细胞的增殖,其D值与对照组比较,差异均有统计学意义(P<0.05或0.01)。O-甲基芒籽碱对GLC-82,HL60的半数抑制浓度分别为83.31、65.59μmol/L。结论O-甲基芒籽碱可抑制人肿瘤GLC-82、HL60细胞的增殖,具有一定的抑瘤作用。     

火龙果保健价值及离体快繁关键技术

火龙果营养丰富,具有高纤维、低热量的特点,其药理作用涉及抑菌,抗炎、增强免疫力、降血糖、降血脂等范畴,市场前景广阔.火龙果火龙果组培快繁中需要解决的几个关键问题有初代培养的污染、不定芽的诱导、增殖过程中激素比例以及生根、移栽等问题,顺利解决以上几个关键问题,借助温室大棚可加快其繁育速度,形成工厂化生产.     

An essential role for BLNK in human B cell development

The signal transduction events that control the progenitor B cell (pro-B cell) to precursor B cell (pre-B cell) transition have not been well delineated. In evaluating patients with absent B cells, a male with a homozygous splice defect in the cytoplasmic adapter protein BLNK (B cell linker protein) was identified. Although this patient had normal numbers of pro-B cells, he had no pre-B cells or mature B cells, indicating that BLNK plays a critical role in orchestrating the pro-B cell to pre-B cell transition. The immune system and overall growth and development were otherwise normal in this patient, suggesting that BLNK function is highly specific.     

不同发酵度茶叶提取物对结直肠癌细胞HCT116 增殖的影响

茶多酚是否具有抗结直肠癌作用目前尚无定论,且有关不同发酵程度(未发酵、半发酵、全发酵)茶叶中茶多酚对结直肠癌细胞作用方面的研究尚未见报道。分别选取黄山毛峰、大红袍、祁门红茶3种不同发酵程度的茶叶,通过采用MTS法以及倒置显微镜下观察这3种茶叶中茶多酚提取物作用结直肠癌细胞HCT116后的细胞形态变化,检测茶多酚提取物对细胞生长的影响,结果显示,在0~35μg/mL浓度范围内,3种茶叶中茶多酚提取物分别作用细胞72 h后,MTS检测结果显示3种茶叶中的茶多酚提取物对HCT116细胞的增殖均有抑制作用(P﹤0.05),不同发酵程度茶叶中的茶多酚提取物对HCT116的半数抑制浓度IC50不同,且选取15、35μg/mL茶多酚浓度作用后的细胞进行形态观察,发现相比对照组均出现不同程度凋亡形态。可见,不同发酵度茶叶的茶多酚提取物均对结直肠癌细胞HCT116有抑制作用,且在一定浓度范围内,随着发酵程度的不同,茶多酚的抑癌效果也不同。     

Spermidine requirement for cell proliferation in eukaryotic cells: structural specificity and quantitation

Six structural homologs of spermidine and five of its precursor, putrescine, were studied for their ability to prevent cytostasis of cultured L1210 leukemia cells induced by alpha-difluoromethylornithine (DFMO), a specific inhibitor of putrescine biosynthesis. High-performance liquid chromatography and competition studies with spermidine indicated that the homologs, which vary in the length of the carbon chain separating the amines, penetrated the cells. The structural specificity of the spermidine carrier was defined. Three of the six spermidine homologs supported cell growth during a 48-hour incubation in the presence of DFMO, indicating that a two-carbon extension of spermidine structure was tolerated for biological function. Two of the five putrescine homologs supported growth after being converted by the cells to their respective spermidine homologs. The central nitrogen of spermidine appears to be essential for function since diamines of chain length comparable to that of spermidine did not prevent DFMO cytostasis. No more than 15 percent of the spermidine normally present in L1210 cells was required for cell proliferation in the presence of DFMO.     

Sindbis virus mutants selected for rapid growth in cell culture display attenuated virulence in animals

Mutants of Sindbis virus were selected for rapid growth in baby hamster kidney (BHK) cell cultures and screened for attenuation of virulence in suckling mice. Comparisons among independently isolated virulent and attenuated strains, as well as a classical reversion analysis, showed that accelerated penetration of BHK cells was correlated with attenuation in vivo. Both phenotypic changes resulted from a reorganization of virion structure as detected by monoclonal antibodies. These results suggest that mutants selected for rapid growth in cell culture may be useful as attenuated vaccines and for studies of the molecular basis of virus pathogenesis.     

The role of B cells for in vivo T cell responses to a Friend virus-induced leukemia

B cells can function as antigen-presenting cells and accessory cells for T cell responses. This study evaluated the role of B cells in the induction of protective T cell immunity to a Friend murine leukemia virus (F-MuLV)-induced leukemia (FBL). B cell-deficient mice exhibited significantly reduced tumor-specific CD4+ helper and CD8+ cytotoxic T cell responses after priming with FBL or a recombinant vaccinia virus containing F-MuLV antigens. Moreover, these mice had diminished T cell responses to the vaccinia viral antigens. Tumor-primed T cells transferred into B cell-deficient mice effectively eradicated disseminated FBL. Thus, B cells appear necessary for efficient priming but not expression of tumor and viral T cell immunity.     

珍稀濒危药材铁皮石斛组培快繁关键技术研究

目的研究珍稀濒危药材铁皮石斛组织培养快速繁殖技术。方法以铁皮石斛茎段为试材,比较植物激素浓度配比、人工光源、炼苗驯化方法等对铁皮石斛组培快繁的影响,摸索出一套可进行组培快繁工厂化生产的技术体系,优选出铁皮石斛组培快繁的最适条件。结果 (1)组培各阶段最佳培养基:原球茎诱导:MS+BA 2.5 mg/L+IBA0.2 mg/L;原球茎分化:MS+BA1.5 mg/L+NAA1.2 mg/L+5%香蕉汁;壮苗生根:MS+NAA 0.15 mg/L+5%香蕉汁、MS+NAA 0.20 mg/L+7.5%香蕉汁、MS+NAA 0.25 mg/L+10%香蕉汁(分阶段补加);(2)人工光源:组培特定光谱节能灯;(3)炼苗方法:水培驯化炼苗。结论通过上述技术的应用,缩短了种苗组培育苗周期,解决了从组培苗到大量栽培的技术,该方法简便易用,且降低了生产成本。     

环腺苷酸对山羊乳腺上皮细胞增殖的影响

为研究环腺苷酸 (c AMP)对乳腺上皮细胞增殖的影响 ,建立了山羊乳腺上皮细胞培养体系。将细胞分为 8个组 ,分别用 1× 10 ,1× 10 2 ,1× 10 3,1× 10 4 ,1× 10 5,1× 10 6 ,1× 10 7pmol/ m L c AMP刺激细胞 ,从中选出效果明显、组间差异显著的 2组作为试验的高剂量组 (1× 10 7pm ol/ m L)和低剂量组 (1× 10 6 pm ol/ m L)。从细胞群体倍增时间、细胞生长曲线和细胞分裂指数 3个方面研究了 c AMP对山羊乳腺上皮细胞增殖的影响。结果表明 ,低浓度的 c AMP有促进细胞增殖的作用 ,高浓度 c AMP有抑制细胞增殖的作用。     

快速筛选环境雌激素酵母细胞的试验研究

通过分子生物学技术将雌激素效应元件(ERE)基本序列插入β-半乳糖苷酶的Lac Z报告基因的上游．并将其置于重组酵母细胞雌激素受体(ER)的调控之下。结果表明：当环境雌激素作用于酵母细胞时,会使ER发生变构效应．与ERE结合使LacZ基因得以表达．其表达量与环境雌激素的污染程度具有剂量效应关系,通过检测β-半乳糖苷酶的活性,可反映环境雌激素的污染程度;与双酚A和苯甲酸雌二醇活性相比较,β-雌二醇活性最强,但双酚A活性明显高于苯甲酸雌二醇。