新石器时代人骨遗骸中古代DNA的提取及X—Y染色体同源基因片段的PCR扩增

从中国新石器时代人骨遗骸中提取出古代ＤＮＡ。通过聚合酶链式反应技术扩增得到Ｘ－Ｙ染色体上的单考贝同源基因片段。由于扩增的基因片段长度具有性别多态性,从而为古代人骨和牙齿提供了分子生物学的性别鉴定。     

cDNA cloning and expression of an apoptosis-related gene, human TFAR15 gene

By means of cDNA-RDA method. some cDNA fragments were found to have high levels of expression during deprivation of GM-CSF (granulocyte macrophage-colony stimulating factor) in a human myeloid cell line, TF-1 cells. One of these tragments was identified as a novel gene. To get the full length of cDNA, rapid amplification of cDNA ends (RACE) and expressed sequence tags (EST) overlapping fragments assembling strategies were used. The novel gene was named TRAF15 (TF-1 cell apoptosis related gene-15), which consists of 1218 nueleotides and encodes 212 amino acids. The putative protein protein product of TFAR15 is partially homologous to C. elegans protein C14A4. 11. TFAR15 mRNA is expressed in fetal liver, kidney, spleen and lung. and also in some human myeloid cell lines. Both of the TFAR15 mRNA and protein were highly expressed in TF-(?) cells after GM-CSF withdrawal. In vitro analysis showed that the recombinant TFAR15 protein co(?)ld inhibit the natural cell death of 293 cells, an embryonic kidney cell     

TGF-β1 diminishes collagen production during long-term cyclic stretching of engineered connective tissue: implication of decreased ERK signaling

Cyclic stretching and growth factors like TGF-β have been used to enhance extracellular matrix (ECM) production by cells in engineered tissue to achieve requisite mechanical properties. In this study, the effects of TGF-β1 were evaluated during long-term cyclic stretching of fibrin-based tubular constructs seeded with neonatal human dermal fibroblasts. Samples were evaluated at 2, 5, and 7 weeks for tensile mechanical properties and ECM deposition. At 2 weeks, +TGF-β1 samples had 101% higher collagen concentration but no difference in ultimate tensile strength (UTS) or modulus compared to -TGF-β1 samples. However, at weeks 5 and 7, -TGF-β1 samples had higher UTS/modulus and collagen concentration, but lower elastin concentration compared to +TGF-β1 samples. The collagen was better organized in -TGF-β1 samples based on picrosirius red staining. Western blot analysis at weeks 5 and 7 showed increased phosphorylation of ERK in -TGF-β1 samples, which correlated with higher collagen deposition. The TGF-β1 effects were further evaluated by western blot for αSMA and SMAD2/3 expression, which were 16-fold and 10-fold higher in +TGF-β1 samples, respectively. The role of TGF-β1 activated p38 in inhibiting phosphorylation of ERK was evaluated by treating samples with SB203580, an inhibitor of p38 activation. SB203580-treated cells showed increased phosphorylation of ERK after 1 hour of stretching and increased collagen production after 1 week of stretching, demonstrating an inhibitory role of activated p38 via TGF-β1 signaling during cyclic stretching. One advantage of TGF-β1 treatment was the 4-fold higher elastin deposition in samples at 7 weeks. Further cyclic stretching experiments were thus conducted with constructs cultured for 5 weeks without TGF-β1 to obtain improved tensile properties followed by TGF-β1 supplementation for 2 weeks to obtain increased elastin content, which correlated with a reduction in loss of pre-stress during preconditioning for tensile testing, indicating functional elastin. This study shows that a sequential stimulus approach - cyclic stretching with delayed TGF-β1 supplementation - can be used to engineer tissue with desirable tensile and elastic properties.     

Dual methylation pathways in lignin biosynthesis

Caffeoyl-coenzyme A (CoA) O-methyltransferase (CCoAOMT) has been proposed to be involved in an alternative methylation pathway of lignin biosynthesis. However, no direct evidence has been available to confirm that CCoAOMT is essential for lignin biosynthesis. To understand further the methylation steps in lignin biosynthesis, we used an antisense approach to alter O-methyltransferase (OMT) gene expression and investigated the consequences of this alteration. We generated transgenic tobacco plants with a substantial reduction in CCoAOMT as well as plants with a simultaneous reduction in both CCoAOMT and caffeic acid O-methyltransferase (CAOMT). Lignin analysis showed that the reduction in CCoAOMT alone resulted in a dramatic decrease in lignin content. The reduction in CCoAOMT also led to a dramatic alteration in lignin composition. Both guaiacyl lignin and syringyl lignin were reduced in the transgenic plants. However, guaiacyl lignin was preferentially reduced, which resulted in an increase in the S/G (syringl/guaiacyl) ratio. We have also analyzed lignin content and composition in transgenic plants having a simultaneous reduction in both CCoAOMT and CAOMT. The reduction in both OMTs resulted in a further decrease in total lignin content. This is in sharp contrast to the effect that resulted from the reduction in CAOMT alone, which only decreased the syringl lignin unit without a reduction in overall lignin content. These results unequivocally demonstrate that methylation reactions in lignin biosynthesis are catalyzed by both CCoAOMT and CAOMT.     

Protein fouling of virus filtration membranes: effects of membrane orientation and operating conditions

The capacity of virus filters used in the purification of therapeutic proteins is determined by the rate and extent of membrane fouling. Current virus filtration membranes have a complex multilayer structure that can be used with either the skin-side up or with the skin-side facing away from the feed, but there is currently no quantitative understanding of the effects of membrane orientation or operating conditions on the filtration performance. Experiments were performed using Millipore's Viresolve 180 membrane under both constant pressure and constant flux operation with sulfhydryl-modified BSA used as a model protein. The capacity with the skin-side up was greater during operation with constant flux and at low transmembrane pressures, with the flux decline or pressure rise due primarily to osmotic pressure effects. In contrast, data obtained with the skin-side down showed a slower, steady increase in total resistance with the cumulative filtrate volume, with minimal contribution from osmotic pressure. The capacity with the skin-side down was significantly greater than that with the skin-side up, reflecting the different fouling mechanisms in the different membrane orientations. These results provide important insights for the design and operation of virus filtration membranes.     

Importance of inlet air velocity in fluid bed dyring of a granulation prepared in a high shear granulator

Conclusions  This report shows that inlet air velocity can play a critical role in maintaining proper fluidization and, ultimately, uniform drying. The mechanism by which air velocity affects fluidization has been discussed by various researchers [4–5]. An indication of good fluidization is a free downward flow of the granules at the sight glass of the drying bowl, but such limited observation could be misleading. In such cases, the exhaust air temperature can be used to detect poor fluidization. If the exhaust air temperature rises more rapidly than anticipated, as seen with process 1 (Figure 1), it is an indication that fluidization is incomplete. In conclusion, a fundamental understanding of the mechanism of fluidization by inlet air will help in the development of a fluid bed drying process that produces uniformly dried granules and minimizes the number of process problems encountered.