Abstract:Due to its super sensitivity and incomparable high throughput, fluorescence-activated cell sorting (FACS) based screening method is emerging as an important ultrahigh-throughput enzymatic screening technology recently. It could detect multiple fluorescent parameters simultaneously and screen enzyme libraries at an extremely high speed (>10⁸/d), thus possesses many advantages over the conventional technologies. FACS based screening method greatly improves our ability in handling large protein libraries and has tremendous potential in various fields such as metagenomics and directed evolution. Herein, recent progress of FACS based enzymatic screening method has been reviewed, with an emphasis on its applications in enzyme directed evolution.

Abstract:Epithelial-mesenchymal transition(EMT) is a process that epithelial cells lose polarity, become mesenchymal cells and acquire the ability of migration and invasion. It exists in many physiological and pathological processes. EMT is involved in a number of signal transduction pathways and performs different physiological functions. During the early stages of embryonic development, both EMT and MET(mesenchymal- epithelial transition) contribute to the formation and development of organs. Moreover, EMT can promote tumor metastasis. EMT also occurs in female mammalian reproduction. In the ovary, EMT is beneficial for repairing process following ovulation. During decidualization, MET may be required for successful uterine anchorage of the embryo. Placental development undergoes an EMT in order to facilitate nutrient and gas exchange between mother and fetus. The failure of EMT process may cause related reproductive diseases.

Abstract:Leucine-rich repeat (LRR) is a common protein domain. LRR domain-containing proteins are present in a large number of cells and tissues in prokaryotes and eukaryotes. The diverse functions of LRR proteins due to their specific locations and the different proteins interacted with them. Many LRR proteins are expressed specially in nerve tissue, and most of the proteins overexpressed in nerve tissue belong to transmembrance protein. As cellular adhesive molecules or ligand receptor proteins, they are involved in a variety of neural physiological activities such as synapse formation, neurite growth, neurotransmitter trafficking and release. The abnormal expression of LRR proteins results in the neurological and psychiatric disorders.

Abstract:The major pathways of cholesterol efflux from macrophages are the transmembrane transports mediated by membrane proteins involved ATP-binding cassette transporters A1, ATP-binding cassette transporters G1 and scavenger receptor class B typeⅠ, which are essential for cellular cholesterol homeostasis. The efficiency of cellular cholesterol efflux is determined by the activity of membrane transporters and regulation of their expression, the quantity and quality of extracellular acceptors and so on. Recent advances indicate that conditions locally in the atherosclerotic lesion, including lipids accumulation, inflammation, oxidative stress, hypoxia and insulin resistance, critically influence the expression of cholesterol transporters, which is in line affects the happen and progress of atherosclerosis associated with a change of cholesterol efflux. This review focuses on the current views on the relative roles of different cellular cholesterol efflux pathways, and the regulation on transporters of lipids accumulation, inflammation, oxidative stress, hypoxia and insulin resistence, which often accompany with the happen of atherosclerotic lesion, aiming at providing new theoretical evidence and drug targets to promote the development of therapies on atherosclerosis.

Abstract:The achievements of embryonic stem (ES) cells and induced pluripotent stem (iPS) cells provide new routes for biological research. However, the problems of immunological rejection, teratoma formation and low efficiency limit the further application. Recently, taking advantage of the systems for iPS cell derivation and traditional induction technologies, scientists induced terminally differentiated cells into functional cells such as cardiomyocytes, neurons and hepatocyte-like cells. These inspiring progresses boost the research on cell differentiation, reprogramming and epigenetics, providing new direction for regenerative medicine studies.

Abstract:It has been suggested that rodent primary somatosensory cortex (SⅠ) can be activated by ipsilateral whisker stimulation, while SⅠ only receives the ascending input from contralateral whiskers. Previous anatomical research revealed two transcallosal pathways transferring whisker information between bilateral cortices: perigranular zone (PGZ) pathway and dysgranular zone (DZ) pathway. But which pathway plays more important role in transferring whisker information remains unknown. We used voltage-sensitive dye (VSD) imaging to visualize the SⅠ activation by stimulating whiskers. We found that the contralateral whisker stimulation first activates the barrel (granular zone, GZ), then the activity forms a propagating wave and spread to the DZ outside the sub-barrel field cortex (BFC). In contrast, ipsilateral whisker stimulation first activates the DZ outside the BFC. The evoked activity in the DZ forms a propagating wave and spreads into the BFC in SⅠ. Inactivating opposite cortex blocks this ipsilateral whisker activation. Electrical stimulus to opposite cortex also first evokes DZ in the imaging cortex. Our results suggested that whisker stimulation first activated the barrel and then DZ in the opposite SⅠ. After a delay of transcallosal transfer, the DZ of the other hemisphere (ipsilateral to the whisker being stimulated) was activated. The callosal fibers connecting the DZs on the two hemispheries play a major role in the SⅠ activation by the ipsilateral whisker stimulation.

Abstract:To overcome the negative effects of antibiotics commonly employed in most aquaculture, here we present a study to examine the feasibility of expressing an antimicrobial peptide by microalga as alternative. An antimicrobial peptide Cecropin B gene was modified according to the codon bias of the nuclear genome in Chlamydomonas reinhardtii. Four repeats of the Cecropin B gene were fused in tandem and each repeat was separated by inserting a cleavable linker peptide sequence (LWMRFA). The artificial DNA (522 bp in length) was inserted into a site between hsp70-RBCS2 promoter and RBCS2 terminator for constructing the expression vector pCB124. A cell-wall deficient strain of C. reinhardtii CC-849 was transformed by using glass bead method with pCB124. A large number of transformants were selected on Tris-acetate-phosphate media containing 10 mg/L Zeomycin. PCR and RT-PCR analyses on the transformants revealed that tandem repeated Cecropin B gene had been integrated into the genome of C. reinhardtii and could express at transcriptional level. The Western blot results confirmed the presence of recombinant antimicrobial peptide Cecropin B in the transgenic algal cells. The total protein was extracted from transgenic algae and its antimicrobial activity was tested. The results indicated that the extracted proteins from transgenic alga showed very strong antimicrobial activity against both Gram negative bacterium (E. coli JM109) and Gram positive bacteria (Bacillus subtilis and Micrococcus lysodeikticus). This finding has provided a new approach for production and utilization of antibacterial bait-algae.

Abstract:Dihydromyricetin (3, 5, 7, 3′, 4′, 5′-hexahydroxy-2, 3-dihydroflavonol, DMY) isolated from Ampelopsis grossedentata is known to have an anti-proliferative effect in vitro on a few cancer cells. However, the exact mechanisms retain unclear. The aim of this article was to study the effect of DMY on cell invasion of highly metastatic human breast cancer MDA-MB-231 cells, and investigate the possible mechanisms. The anti-proliferation effect of DMY on MDA-MB-231 cells was determined by the MTT assay. The gelatinolytic activity was assessed by gelatin zymography. The mRNA and the protein expression levels of MMP-2/-9 were evaluated by Real-time PCR and Western blot assay, respectively. The effect of DMY on cell invasion was observed by a transwell model. Results indicated that DMY inhibited the proliferation of MDA-MB-231 cells in a dose-dependent manner, and the IC₅₀ value was about 73.6 mg/L after treated by DMY for 48 h. DMY suppressesed gelatinase activity and MMP-2/-9 protein expression levels in a dose-dependent manner, and restrained MMP-2/-9 mRNA expression levels. In addition, DMY inhibited the invasion of MDA-MB-231 cells in a dose-dependent manner without cytotoxicity against the cancer cells. DMY can inhibit proliferation and invasion of MDA-MB-231 cells, and invasion inhibition may be related to the down-regulation of the expression levels of MMP-2/-9 proteins.

Abstract:Small proteins (< 100 amino acids) are prevalent in all three domains of life. Earlier studies have been focusing on a limited number of small protein families in specific organisms and developing genome-wide algorithms to identify short open-reading-frames or sORFs. Here the in silico analyses on small proteins (SPs) include both known SPs and genes with sORFs. RefSeq proteins that shorter than 100 amino acids in length are defined as SPs and are grouped according to their sequence conservation within lineages of eukaryotes, vertebrates, and mammals. Biological roles of the grouped SPs are found basically performing lineage-specific functions. Tissue-specificity of human SPs are also investigated and showed that a majority of the human-specific SPs are tissue-specific and that most of the human SPs originated after the split of vertebrates and invertebrates are mostly universally expressed. In addition, the results indicated that some of the eukaryotic SPs perform lineage-specific functions and they evolve and express in certain unique ways.

Abstract:Meiotic recombination is driver of genome evolution. It is important to explore the rule of genome evolution under the control of evolutionary pressure linked to recombination. The coding information quantity of a genome (CIQ) always grows during evolution. Recombination rate is proportional to selection efficiency, thus the growing rate of coding information quantity of a genome (GR_CIQ) might be mediated by recombination rate. In this study, a parameter is defined to characterize GR_CIQ, and the correlation between GR_CIQ and recombination rate is analyzed in the human genome. The results show that there is a positive correlation between them, indicating recombination is likely to be an important pathway to increase GR_CIQ.

Abstract:Posttranslational chlorination of tyrosine residues in proteins produce 3-chlorotyrosine (3-Cl-Tyr), which is associated with several diseases, including Alzheimer's disease, asthma, atherosclerosis and acute myocardial infarction. High level of 3-chlorotyrosine has been found in ApoA1 protein in atherosclerosis patients, indicating that it may play important role in disease. Here we report a new method to facilitate the site-specific incorporation of 3-chlorotyrosine into proteins at specific sites. Such a new method may be very useful to probe the regulatory role of tyrosine chlorination in protein function. Compared to tyrosine (Tyr), 3-Cl-Tyr has lower pK_a. We replaced the green fluorescent protein (GFP) and photoactivatable protein mEOS2 chromophore Tyr (Tyr66 in GFP) by 3-Cl-Tyr, lowering the chromophore pK_a to 4.2 and 4.7, respectively. These mutant fluorescent proteins with lower pK_a may be advantageous for labeling proteins in acidic organelles such as lysosome and phagosome.