Abstract:Flowering is one of the most important progresses for most plants during the transition from vegetative growth to reproductive growth. There are many factors that affect the flowering, including two main external factors, light and temperature, and the internal factors such as gibberellin acid (GA) and autonomous elements. At present, the late-flowering mutants are fallen into four pathways: photoperiod pathway, vernalization pathway, autonomous pathway and GA pathway according to factors described above. Through several floral integrators, such as SOC1, FT and LFY, the multiple flowering regulatory pathways control the flowering finely under the variable environmental condition and physiological condition.

Abstract:Oligosaccharides are one of the essential physiological constituents of glycoproteins and glycolipids on mammalian cell surfaces and microbial metabolites. They have considerable potential as therapeutics but are only now slowly assuming this important role. One of the reasons for their slow development has been the considerable difficulty in synthesizing oligosaccharides on the scale necessary for their clinical evaluation. Classical chemical and enzymatic methods both have limitations in synthesizing large-scale oligosaccharides. In recent years, the rapid progress on molecular biotechnology has promoted the development of retaining glycosidases in oligosaccharides synthesis, which led to the production of a novel class of enzymatic activities termed the glycosynthases. These new enzymes are retaining glycosidase mutants in which the catalytic nucleophile has been converted to a non-nucleophilic residue，synthesizing oligosaccharides in high yields ( the highest yields reach 99%) without any hydrolysis. Furthermore thioglycoligases and thioglycosynthases have been developed subsequently in the past three years. Glycosynthases can be screened in high-throughput assay by the two-plasmid system and the yeast three-hybid system respectively. Their activity can be significantly enhanced by substituting alternative residues for nucleophile, additional random mutations and optimizing reaction conditions. Their regioselectivity can be modified through changes in receptors.

Abstract:Parkinson’s disease (PD) is one of the most frequent neurodegenerative disorders. α-Synuclein was the first“PD gene”to be discovered. The involvement of α-synuclein in PD was first suspected after two different α-synuclein mutations were identified in two kindreds with autosomal-dominant PD. However, the discovery that α-synuclein is the major component of Lewy bodies-pathological hallmarks of PD, confirmed its role in PD pathogenesis. Pathological aggregation of α-synuclein might be responsible for neurodegeneration. Multiple factors have been shown to affectα-synuclein aggregation in vitro or in vivo. In addition, soluble oligomers of α-synuclein might be even more toxic than the insoluble fibrils found in degenerative diseases. So it is significant to investigate factors affectingα-synuclein aggregation, especially their accurate effects on the aggregation process.

Abstract:Aptamers are short single-stranded nucleic acid ligands that are capable of binding almost any targets with low nano- to picomolar affinities and exceptional specificities. They are selected out of a large combinatorial oligonucleotide library through an in vitro evolution process termed SELEX (systematic evolution of ligands by exponential enrichment). The unique advantages of high-throughput screening technique and aptamers in precise recognition as well as easiness to synthesis and modification bring aptamers a bright prospect in analytical chemistry, biology and medicine research. The recent advances in the SELEX technique and aptamers are reviewed.

Abstract:Three myelin proteins, Nogo-A, MAG and OMgp, transduce their neurite-outgrowth inhibitory signal through a common receptor complex: NgR/ p75^NTR (or TROY). Recently, LINGO-1 is identified as another essential component and regulator for the Nogo-66 receptor/p75 signaling complex. LINGO-1 is restricted to express in CNS, neuronal LINGO-1 is shown to be involved in the signal transduction from three myelin proteins, and Lingo-1 in oligodendrocyte negatively regulates the differentiation and myelination of oligodendrocyte. To investigate the potential activity of LINGO-1 in neuronal apoptosis, LINGO-1-Fc fusion protein including the extracellular LRR and IgC2 domain, was used as functional antagonist to study its protective effect on low-potassium induced apoptosis of cerebellar granule neurons (CGNs). In judgement of the apoptotic nuclei stained by Hoechst, LINGO-1-Fc pretreatment for 2 h significantly prevents apoptosis of CGNs. Although GST-LINGO-1 protein, including the LRR domain, binds to the CGN cultures in the same way with LINGO-1-Fc, it doesn't prevent the apoptosis of CGNs. These results indicate that LINGO-1-Fc fusion protein prevents low-potassium induced apoptosis of cerebellar granule neurons in certain conditions and this activity is probably IgC2 domain dependent.

Abstract:A murine embryonic stem cell (ESC) line stably expressing the enhanced green fluorescent protein (EGFP) under the transcriptional control of the smooth-muscle-specific SM22α promoter to further characterize development of the vascular smooth muscle cells (VSMCs) differentiated from ESCs is established. In SM22α-EGFP expressing ESC-derived embryoid bodies(EBs), a distinct sublineage of VSMCs could be identified by EGFP fluorescence. The SM22α promoter was switched on at day 11, and EGFP-positive cells increased gradually and reached peak at day 30. The specificity of EGFP positive cells was corroborated by RT-PCR analysis and immunostaining with antibodies against known markers for VSMCs. VSMCs were heterogeneous in their morphology in plating EBs,and could be divided into two categories: spindle-shaped or epithelioid, polygonal cells. These results suggest that SM22α-EGFP expression enables the identification of ESC -derived VSMCs by their fluorescence and morphology.

Abstract:The major photosynthetic complexes PSⅠ, PSⅡ, the cytochrome b₆f complex and the ATP synthase complex are located in the thylakoid membrane. Here, the newly developed split-ubiquitin two hybrid system was used to investigate protein-protein interactions of thylakoid membrane proteins. The reaction center D1 protein of PSⅡ, which is encoded by plastid gene psbA, was used as the bait protein, while the D2 encoded by plastid gene psbD, another PSⅡ reaction center protein, and Cytb₆ encoded by plastid gene petB, a component of Cytb6f complex, were used as prey proteins. The yeast two hybrid analysis showed that the D1 protein interacts with D2, but not with the Cytb₆. This result confirms the protein interaction model of thylakoid membrane protein complex, and also means the availability of this system in detecting thylakoid membrane protein interactions. Thus, the split-ubiquitin two hybrid systems could provide an efficient tool to reveal the regulation mechanism of chloroplast proteins biogenesis.

Abstract:Two kinds of ectopic expression of porcine growth hormone-releasing hormone (GHRH) plasmids, ppG-A53f-H6-GHRH (ppG-H6) and ppG-A53f-H4-GHRH (ppG-H4), were constructed by using a myogenic expression vector which has α-actin expression elements. After the animal was injected in the muscle with the two plasmids, the body-weight data at the 0 / 3/ 7/ 11/ 14/ 17/ 20/ 24/ 27/ 31/ 34/ 38/ 41st days were collected. Rat plasma from blood collected at the 20/ 27/ 34/ 41st days was made and growth hormone (GH) levels were determined by radio immunoassay (RIA). The results indicated that ppG-H6 and ppG-H4 do enhance the rat growth compared to the control, with the ppG-H6 treated group showing a more effective response. Compared with the control group, at the 34th day after injection, the weight gain of the ppG-H6 group was significant ((200.57±3.99) g vs (185.85±9.45) g, P < 0.05). Furthermore, the GH maintains on a stable level in group ppG-H6 and ppG-H4 compare to control by the end of experiment, which support that the injection of ppG-H6 and ppG-H4 plasmids caused the body-weight of rat increasing. The results imply that injection of ectopic expression of porcine growth hormone-releasing hormone (GHRH) plasmids is a possible way to enhancing animal growth.

Abstract:Ethylene regulates sex expression in cucumber plants (Cucumis sativus L.). ACC synthase is a key factor during the ethylene biosynthesis. Pairs of PCR primers were synthesized corresponding to the conserved sequences of ACC synthase gene family. The 1 188 bp DNA fragment of ACC synthase gene (CS-ACS2) was amplified from genomic DNA of 8 different sexual phenotypes of cucumber respectively (GenBank accession number is DQ115884～DQ115886 and DQ115875～DQ115879). 8 SNPs have been identified by sequences analysis between 3 monoecious lines and 5 subgynoecious lines and gynoecious lines, which including 4 A←→G and 4 T←→C transition. Of these 8 SNPs, one locus is in intron and 7 loci in exons. Of the 7 SNPs located in exons, 3 SNPs are non-coding SNPs and 4 SNPs are coding SNPs (cSNPs) of which 3 induced changes of encoding amino acid of ACC synthase. The results of SNPs from subgynoecious lines and gynoecious lines suggest that single nucleotide mutation events of CS-ACS2 might be correlated with the development of subgynoecious lines and gynoecious lines in cucumber. Furthermore, CAPS marker C-MT705 was developed for identifying elite subgynoecious cultivar MT-705, which could be valuable in cucumber breeding. Besides, the SNPs and CAPS markers obtained in the study enriched molecular markers of cucumber.

Abstract:GDP-mannose-3′, 5′-epimerase (GME), which converts GDP-mannose into GDP-L-galactose, is essential for the biosynthesis of L-ascorbic acid in higher plants. The molecular characterization of two GME genes from rice has been reported. Firstly, both cDNAs were isolated from the rice mature leaves using RT-PCR technique. By comparing their sequences with homologues from other plants, it was found that GME genes were highly conserved among plant species, though phylogenetic study showed that all known GMEs could be divided into two distinct groups corresponding to monocots and dicots. Secondly, the genomic organization of rice OsGME genes was investigated, and a similarity of splice patterns was revealed. Finally, the expression patterns of the two cDNAs have been studied in various tissues and under different stress conditions by semiquantitative RT-PCR assay. The results showed that the OsGME1 transcript was up-regulated in response to cold stress, and gibberellin might regulate L-ascorbic acid levels by affecting transcription of both OsGME genes.

Abstract:The gene fragment of urokinase catalytic domain mutant (C279A/N302Q) was amplified by the site-mutated PCR method and was cloned into pPICZαA secretory expression plasmid. The recombinant plasmid was transformed into yeast X-33 and selected with Zeocin. The recombinant protein was captured by the cation exchange chromatography SPFF and was purified to 99% of purity. The recombinant mutant protein was crystallized by the method of sitting-drop vapor diffusion. These crystals diffracted to 1.45 Å with synchrotron X-ray.

Abstract:According the EST sequence contained a UBA_NAD binding domain, a novel gene UBAL (ubiquitin-activating enzyme like protein) was cloning both in mouse and chicken by the homology scanning and EST splicing methods. UBAL contains the conserved domain Ⅰ of Uba1, ATP binding motif and putative active site Cys. The expression profile of mUBAL was detected in most of the tissues of the 11 investigated tissues, especially in kidney, testis, brain and heart. Whole-mount in situ hybridization with the coding region of mUBAL showed that expression of mUBAL was presented in the early streak stage of mouse embryo and migrated anterior with anterior visceral endoderm (AVE) and then in the telencephalon. The gUBAL expression was also found in the brain of HH14，HH 16 and HH18 chick embryos. The conserved structures and expression patterns of UBAL suggested that UBAL may play important roles in the developing brain of embryo and adult tissues as E1 like enzyme.

Abstract:A novel gene, which was a homologue of Arabidopsis COI1 was isolated from rice (Oryza sativa L.) by RT-PCR and designated as OsCOI1. It encoded a protein of 595 amino acids. The similar F-box motif and 16 leucine-rich repeats were found in the deduced protein OsCOI1. OsCOI1 and COI1 showed high homology (74%) at amino acid level. Semi-quantitative RT-PCR and Northern blot analysis demonstrated that the expression of OsCOI1 in rice varied obviously after treatment with MeJA and ABA but was not affected by SA and ET, suggesting that the specific function of OsCOI1 in JA signal pathway and related ABA pathway.

Abstract:A paper published in Proc Natl Acad Sci USA On March 14，2006，by Ligang Wu et al，New York University School of Medicine，indicating that rapid readenylation is a new mechanism of miRNA inhibiting gene expression.