Science in China. Series C, Life Sciences / Chinese Academy of Sciences最新文献

Fatty acid desaturase-2 (FAD2) introduces a double bond in position Delta12 in oleic acid (18:1) to form linoleic acid (18:2 n-6) in higher plants and microbes. A new transgenic expression cassette, containing CMV promoter/fad2 cDNA/SV40 polyA, was constructed to produce transgenic mice. Among 63 healthy offspring, 10 founders (15.9%) integrated the cotton fad2 transgene into their genomes, as demonstrated by PCR and Southern blotting analysis. All founder mice were fertile and heterozygous fad2 female and nontransgenic littermates were used for fatty acid analysis using gas chromatography. One fad2 transgenic line showed substantial differences in the fatty acid profiles and the level of linoleic acid was increased 19% (P<0.05) in transgenic muscles compared to their nontransgenic littermates. Moreover, it exhibited an 87% and a 9% increase (P<0.05) in arachidonic acid (20:4 n-6) in muscles and liver, compared to their nontransgenic littermates. The results indicate that the plant fad2 gene can be functionally expressed in transgenic mice and may playan active role in conversion of oleic acid into linoleic acid.

The description and differentiation of the so-called "Cold" and "Hot" natures, the primary "Drug Naure" of Chinese medicine, is the focus of theoretical research. In this study, the divergency between the "Cold" and the "Hot" natures was investigated through examining the temperature tropism of mice affected by Coptis chinensis Franch and its processed materials by using a cold/hot plate differentiating technology. After exposure to C. chinensis Franch, the macroscopic behavioral index of the remaining rate (RR) on a warm pad (40 degrees C) significantly increased (P<0.05), suggesting the enhancement of Hot tropism. The internal indexes of adenosine triphosphatase (ATPase) activity and oxygen consuming volume decreased significantly (P<0.05), suggesting the decapability of energy metabolism. This external behavior of Hot tropism might reflect the internal Cold nature of C. chinensis Franch. However, the processed materials of C. chinensis Franch exhibited a different Cold nature in temperature tropism compared with crude C. chinensis Franch (CC): the Cold nature of bile-processed C. chinensis Franch (BC) enhanced while the ginger-processed C. chinensis Franch (GC) changed inversely. The changing sequence was consistent with the theoretical prognostication. It is indicated that the external Cold & Hot natures of Chinese medicine may possibly reflect in an ethological way for the changes of animal's temperature tropism which might be internally regulated by the body's energy metabolism.

Many proteins exist as homo-oligomers in living organisms wherein the change of oligomeric status apparently serves as an effective means for modulating their biological activities. We have previously reported that the homo-decameric RbsD from Escherichia coli undergoes stepwise disassembly and non-stepwise reassembly. Here the structural status of the urea-induced RbsD disassembly intermediates was examined, mainly using urea-containing polyacrylamide gel electrophoresis and chemical cross-linking. Such intermediates were found to remain oligomeric while losing their intact secondary structures. Such disassembly intermediates were able to effectively refold when the concentration of the urea denaturant was reduced to a lower level, or to refold/reassemble into the native decamers when urea was completely removed, as detected by non-denaturing polyacrylamide gel electrophoresis. These novel observations strongly suggest that the assembly of oligomeric proteins may occur before the completion of subunit folding.

The traditional Chinese medicine concepts of "Xinxueyuzuzheng (heart blood stasis obstruction pattern)" and "Qiyinliangxuzheng (qi and yin deficiency pattern)" for myocardial ischemia rat models were constructed in the present study. Endogenous metabolites in rat plasma were analyzed using the GC/TOF-MS-based metabonomic method. Significant metabolic differences were observed between the control and two model groups, and the three groups were distinguished clearly by pattern recognition. Compared with those of the control, the levels of hydroxyproline, threonic acid, glutamine and citric acid were strikingly up- or down-regulated in model rats. The metabolites contributing most to the classification between the two "pattern" rats were identified, such as valine, serine, threonine, ornithine, hydroxyproline, lysine, 2-hydroxybutanoic acid, 3-hydroxybutanoic acid, galactofuranose and inositol. These compounds were indicated as the potential biomarkers. The results suggested that the two "patterns" are involved in dysfunction in oxidative stress, energy metabolism and amino acid metabolism. These findings also provided the substantial foundation for exploring the scientific connotation of these two "Zhengxing (pattern types)" of myocardial ischemia, and "Bianzheng (pattern identification)".

Using different endothelial/smooth muscle cell co-culture modes to simulate the intimal structure of blood vessels, the water filtration rate and the infiltration/accumulation of LDL of the cultured cell layers were studied. The three cell culture modes of the study were: (i) The endothelial cell monolayer (EC/Phi); (ii) endothelial cells directly co-cultured on the smooth muscle cell monolayer (EC-SMC); (iii) endothelial cells and smooth muscle cells cultured on different sides of a Millicell-CM membrane (EC/SMC). It was found that under the same condition, the water filtration rate was the lowest for the EC/SMC mode and the highest for the EC/Phi mode, while the infiltration/accumulation of DiI-LDLs was the lowest in the EC/Phi mode and the highest in the EC-SMC mode. It was also found that DiI-LDL infiltration/accumulation in the cultured cell layers increased with the increasing water filtration rate. The results from the in vitro model study therefore suggest that the infiltration/accumulation of the lipids within the arterial wall is positively correlated with concentration polarization of atherogenic lipids, and the integrity of the endothelium plays an important role in the penetration and accumulation of atherogenic lipids in blood vessel walls.

Elucidation of maternal-fetal tolerance mechanisms clarifies the role of regulatory T cells (Treg) in transplant tolerance. This study aim to investigate the effect of pregnancy on paternal skin allograft survival. Flow cytometry techniques, mixed lymphocytes reaction (MLR), PCR, real-time PCR and skin transplantation were key methods. Treg increased significantly from 4.2% before pregnancy to peak at 6.8% day 8 after pregnancy. Both heme oxygenase-1 (HO-1) and indoleamine 2,3-dioxygenase (IDO) mRNA express high in placenta while low in spleen (P<0.05). Although Treg increased during pregnancy, and splenocytes from the pregnant mice showed lower MLR response toward the paternal stimulator, single time pregnancy showed no significant protective effect on paternal skin allograft survival in the tested condition.

microRNAs (miRNAs) are a class of endogenous, non-coding, short (approximately 21 nt) RNAs directly involved in regulating gene expression at the post-transcriptional level. Previous reports have noted that plant miRNAs in the plant kingdom are highly conserved, which provides the foundation for identification of conserved miRNAs in other plant species through homology alignment. Conserved miRNAs in wheat are identified using EST (Expressed Sequence Tags) and GSS analysis. All previously known miRNAs in other plant species were blasted against wheat EST and GSS sequences to select novel miRNAs in wheat by a series of filtering criteria. From a total of 37 conserved miRNAs belonging to 18 miRNA families 10 conserved miRNAs comprising 4 families were reported in wheat. MiR395 is found to be a special family, because three members belonging to the same miR395 family are clustered together, similar to animal miRNAs. MiRNA targets are transcription factors involved in wheat growth and development, metabolism,and stress responses.

To investigate the response of key enzymes to nitrogen (N) rates in cotton fiber and its relationship with fiber strength, experiments were conducted in 2005 and 2006 with cotton cultivars in Nanjing. Three N rates 0, 240 and 480 kgN/hm(2), signifying optimum and excessive nitrogen application levels were applied. The activities and the gene expressions of the key enzymes were affected by N, and the characteristics of cellulose accumulation and fiber strength changed as the N rate varied. Beta-1,3-glucanase activity in cotton fiber declined from 9 DPA till boll opening, and the beta-1, 3-glucanase coding gene expression also followed a unimodal curve in 12-24 DPA. In 240 kgN/hm(2) condition, the characteristics of enzyme activity and gene expression manner for sucrose synthase and beta-1,3-glucanase in developing cotton fiber were more favorable for forming a longer and more steady cellulose accumulation process, and for high strength fiber development.

A full length cDNA encoding the growth hormone receptor (GHR) of Chinese sturgeon was cloned in order to investigate the mechanism of growth hormone in regulating the growth of Chinese sturgeon. The open reading frame of the cloned Chinese sturgeon growth hormone receptor (csGHR) cDNA encodes a trans-membrane protein of 611 amino acids containing all the characteristic motifs of GHR. By sequence alignment, substitutions of amino acid residues highly conserved in other species were identified. Using the CHO cell culture system, the function of csGHR and the biological significance of the amino acid substitution in csGHR were examined. The promoter of serine protease inhibitor 2.1 (Spi2.1) was trans-activated upon stimulation of seabream GH (sbGH) in the csGHR-expressing CHO cells. Furthermore, CHO cells stably expressing csGHR were stimulated to proliferate by sbGH. In agreement with our previous report, Chinese sturgeon growth hormone-binding protein (csGHBP) was detected in the culture medium of CHO cells stably expressing csGHR. Mutation of Asp residue in the ligand binding motif in csGHR to Glu significantly enhanced csGHR's biological function, whereas mutation of Asp residue to Ala decreased its biological function. The results demonstrated that the cloned csGHR was of full biological function and the csGHBP could be generated through proteolysis of csGHR. These findings might provide new insights into thoroughly understanding the regulatory mechanism of Chinese sturgeon growth.

Temperature sensitivity of soil respiration (Q(10)) is an important parameter in modeling the effects of global warming on ecosystem carbon release. Experimental studies of soil respiration have ubiquitously indicated that Q(10) has high spatial heterogeneity. However, most biogeochemical models still use a constant Q(10) in projecting future climate change and no spatial pattern of Q(10) values at large scales has been derived. In this study, we conducted an inverse modeling analysis to retrieve the spatial pattern of Q(10) in China at 8 km spatial resolution by assimilating data of soil organic carbon into a process-based terrestrial carbon model (CASA model). The results indicate that the optimized Q(10) values are spatially heterogeneous and consistent to the values derived from soil respiration observations. The mean Q(10) values of different soil types range from 1.09 to 2.38, with the highest value in volcanic soil, and the lowest value in cold brown calcic soil. The spatial pattern of Q (10) is related to environmental factors, especially precipitation and top soil organic carbon content. This study demonstrates that inverse modeling is a useful tool in deriving the spatial pattern of Q(10) at large scales, with which being incorporated into biogeochemical models, uncertainty in the projection of future carbon dynamics could be potentially reduced.