Abstract:Induced pluripotent stem cells (iPSCs) are derived from somatic cells that regain pluripotency by the nuclear programming with exogenous factors. iPSCs have immense potential applications in establishing disease models and understanding disease mechanisms, cell therapies, drug discoveries and assessments, etc. Over the past several years, scientists made much effort to improve reprogramming technology and achieved many breakthroughs in the research and applications of iPSCs. However, moving toward the eventual goal of clinical application, it is necessary to overcome challenges such as low reprogramming efficiency and risk due to tumorigenicity, besides the detailed mechanism of reprogramming remains to be elucidated. Here, combined with the recent advances in iPSCs, the progress of iPSCs were reviewed for research and applications. The current problems and the directions of future iPSCs research were discussed.

Abstract:Recent studies demonstrated that the kidney has the ability to express transferrin receptor-1 (Tf R1), divalent metal transporter-1 (DMT1), ferroportin-1 (FPN1), iron regulatory protein (IRP), hepcidin (Hepc) and other iron metabolism proteins. The existence of these proteins and the relevant studies about their functions suggested that the kidney might be an efficient way of eliminating excess iron, and therefore play an important role in human iron homeostasis.

Abstract:Ageing, as an ineluctable physiological process for all organisms, is a complex life activity induced by several factors. Currently yeast cell becomes an ideal model organism which is generally acknowledged, and many mechanisms and regulatory factors have been discovered by the insightful research of yeast. One of its well-established ageing models，called chronological ageing, is conserved with other higher eukaryotic cells，especially mammalian cells, thus attracted much attention on such a study. Two ageing models in yeast were compared, the research progress in the studies on the molecular mechanisms of yeast chronological ageing was introduced, and several complicated regulatory pathways were expounded including the effects given by calorie restriction and medicine addition on Ras/PKA, Sch9 and Tor regulatory pathways which are nutrient-dependent. Meanwhile, some significant future issues in this field are mentioned and anticipated as reference to dig much further in the comprehensive understanding of the ageing mechanisms in higher living organisms, especially human beings.

Abstract:The study of cardiac progenitor cells (CPCs) is important for understanding the pathogenesis of congenital heart diseases and treating cardiovascular diseases. The mammalian heart is derived from distinct sets of CPCs. T-box transcription factor Tbx18 is expressed in the developing epicardium of the heart and play key roles in heart developing. In order to monitor and elucidate the differentiation potential of Tbx18⁺ CPCs in tissues and living cells, Tbx18 genetic fate-mapping model, Tbx18-Cre/Rosa26R-EYFP and Tbx18-Cre/Rosa26R-LacZ double-heterozygous mice, were founded by Cre-LoxP system. These double-heterozygous mice were useful in monitoring the fate of Tbx18⁺ cells by Cre expression, and tracing the lineage of the cells in embryos and adult mice. YFP⁺ cells can be easily isolated from heart of Tbx18-Cre/Rosa26R-EYFP double-heterozygous mice by fluorescence activated cell sorter(FACS) and be monitored under an inverted confocal microscope. X-gal staining of genetic fate-mapping model revealed that atria, ventricular septum, ventricular wall, coronary vascular and atrioventricular valves can be generated from Tbx18 lineages. Here it was showed that Tbx18⁺ CPCs can differentiate into anticardiac troponin T(cTNT ) positive cardiomyocytes and anti-smooth muscle myosin heavy chain11 positive smooth muscle cells in vivo by immunofluorescence. The heart is a complex organ composed of a diverse set of muscle and non-muscle cells. It was speculated that Tbx18 may play an important role in regulating the signal pathway of progenitor cells differentiating into myogenic cell lineages. These results identify Tbx18 as a marker of cardiac progenitors cells by Tbx18 genetic fate mapping mice, and lay the foundation for researching the differentiation potential of cardiac progenitors into cardiomyocyte lineages in the field of cardiac regeneration and repair.

Abstract:The effect of hypoxia on expression and function of L-glutamate/L-aspartate transporter (GLAST) and glutamine synthetase(GS) was investigated in mouse retinal Müller cells(RMCs). Mouse RMCs were cultured by enzymatic digestion method. RMCs cultures were treated with CoCl₂ (125 μmol/L) for 6 h, 12 h, 24 h, 48 h or 72 h respectively in vitro. RMCs cultures were maintained without CoCl₂ in normal control group. The expression of GLAST and GS was determined by RT-PCR, Western blotting and immunocytochemical staining. L-[3,4-³H]- glutamic acid uptake was used to quantify glutamate uptake function of RMCs. The apoptosis of RMCs was confirmed by annexin V-FITC/PI staining. In early-stage of CoCl₂-induced hypoxia (treated with CoCl₂ for 6 h, 12 h, 24 h or 48 h)，the expression of GLAST was up-regulated (P < 0.001) and reached the maximum when RMCs have been treated with CoCl₂ for 12 h (P < 0.05). After RMCs having been treated with CoCl₂ for 72 h, the expression of GLAST had no difference compared to normal control (P > 0.05). CoCl₂-induced hypoxia (treated with CoCl₂ for 6 h, 12 h, 24 h, 48 h or 72 h) also up-regulated the expression of GS (P < 0.001) which reached the maximum when RMCs have been treated with CoCl₂ for 48h (P < 0.001). The L-[3,4-³H]-glutamic acid uptake of hypoxia groups were the higher than normal control group (P < 0.05), and after having treated RMCs with CoCl2 for 48 h, the L-[3,4-³H]-glutamic acid uptake was the highest (P < 0.005). Treatments with CoCl₂ did not induce apoptosis in RMCs. In early hypoxia stage, GLAST and GS were up-regulated and extracellular glutamate uptake increased. However, continued hypoxia causes gradual dysfunction and reduction of GLAST and GS, as well as glutamate uptake.

Abstract:In a complex acoustical environment, the ability to discriminate the level of a sound is an important function of auditory system to accurately process sound signal information. Previous studies regarding human sound level discrimination were investigated in monaural condition. However, in natural acoustical environments, human discriminate sound level and spatial information binaurally. The effect of a preceding sound was determined upon the level discrimination of a successive sound by measuring the just noticeable difference (JND) of the level of the successive sound in binaural conditions. The data were collected in close-field, dichotic acoustical conditions. The level and the spatial azimuth of both the preceding and the successive sounds were manipulated by changing the average binaural level (ABL) and the interaural level difference (ILD) of the sounds. Compared with the JND of level in quiet, low level preceding sound did not significantly change the JND of the successive sound. However, moderate and high levels (ABL ≥40 dB) of preceding sound significantly increased the JND of the level of the successive sound. The JNDs were monotonically increased with increasing level of the preceding sound. When the preceding sound level was constant, the effect of preceding sound on the level discrimination of the successive sound was decreased with increasing level of the successive sound, and the effect was not significant when the level of the successive sound was high. These results were different from the previous findings in monaural conditions. Also, the present study did not found a significant effect of ILD difference between the preceding and the successive sound on the level discrimination of the successive sound.

Abstract:The residues associated with substrate binding in GroupⅠ chaperonin GroEL are hydrophobic. However, the corresponding residues in groupⅡ chaperonin ATcpnβ from Acidianus tengchongensis are hydrophilic.When these hydrophilic residues in ATcpnβ were mutated to hydrophobic residues, i.e. residues 236 from G to Y, 237 from M to F, 288 from D to L, 295 from A to V, 313 from A to V and 314 from K to V, they enhanced the inhibitory effect of ATcpnβ on the refolding of acid-denatured GFP and the inhibition activity of citrate synthase (CS) thermal aggregation. Hydrophobic interaction may contribute more to peptides binding affinity both in groupⅠ and groupⅡ chaperonin. Chaperonins have been proved to have ATP-dependent peptides refolding ability. However, it is still unclear whether peptides binding ability of chaperonins is ATP-dependent. Surface plasma resonance (SPR) analysis is used to test chaperonin binding ability to different peptides with different denaturing level. These assays revealed that ATcpnβ could capture guanidine hydrochloride denatured malate dehydrogenase in a Mg²⁺/ATP independent manner while it bind thermal aggregated citrate synthase or lysozyme in a Mg²⁺/ATP dependent manner. It has been proposed that chaperonin conformatinal changes induced by Mg²⁺/ATP to expose more hydrophobic surface is required for chaperonin capturing thermal aggregated peptides which has larger hydrophobic surfaces.

Abstract:Time perception is a fundamental ability of human beings．Daily experience indicates that time perception is easy to be affected by emotion. However, the emotional influence was often accompanied by active attention and explicit motor response in previous studies. Here the question whether implicit time perception could be influenced by emotional faces is addressed. Observers actively completed a visual discrimination task of emotional faces (fearful, happy and neutral faces) while they passively listened to a sequence of tones with 80% standard stimulus onset asynchronies (SOAs) (800 ms) and 20% deviant SOAs (400, 600, 1 000 and 1 200 ms). Event-related potentials (ERPs) were recorded for frequent standard SOAs and rare deviant SOAs. The two short deviant SOAs (400 and 600 ms) elicited two changed-related ERP components: the mismatch negativity (MMN) and the P3a. The MMN amplitude, which indexes the early detection of irregular time changes, was modulated by facial emotion. Fearful faces elicited reduced MMN as compared with happy faces and neutral faces did for the shorter deviant conditions, and happy faces elicited enhanced P3as as compared with fearful and neutral faces did. The current ERP study suggested that shorter time perception of auditory modality was affected by visual emotional faces, and fearful faces decreased the accuracy of implicit time perception.

Abstract:Research of protein 3D structures plays a key role in molecular biology, cell biology, biomedicine, and drug design. The protein fold type reflects the topological pattern of the structure's core. Fold recognition is an important method in protein sequence-structure research. On the 53 fold types which have more than 10 samples in LIFCA were selected. The functional domain composition is introduced to predict the fold types of a protein or a domain. After testing 9 211 proteins with less than 95% sequence identity from the Astral 1.65 database, the average sensitivity, specificity and Matthew's correlation coefficient (MCC) of the 53 fold types were found to be 96.42%, 99.91% and 0.91, respectively. The result indicates that using the functional domain composition to represent a protein is very promising for protein fold recognition. And though based on simple classification rules, LIFCA can concentrate the functional features of proteins, reflecting the corresponding relation between structure and function.

Abstract:A basic research subject is the study on interactions between proteins, DNA and RNA. Majority of DNA and RNA-binding proteins are self polymerization-prone and may form aggregates that are difficult to bind DNA or RNA, thus hampering experiments. Labeling the proteins with fluorescein isothiocyanate significantly inhibits this tendency and markedly increases the binding efficiency of these proteins to bind nucleic acid molecules. This simple method has been utilized in the investigation on binding of C/EBPβ 3′UTR RNA by cytokeratin 18.

Abstract:DNA methylation is identified as an elaborate epigenetic element to regulate binding of transcription factor to gene promoter region. With latest highthroughput technology, it is convenient to accurately test methylation level in experiment, which opens a door to investigate how methylation affects transcription factor. A general model is presented to sense methylation effect on transcription factor in a specific cell. In the model, an inverse sigmoid function is adopted to depict effect of DNA methylation to binding ability of transcription factors with two parameters as center C and steepness S. For each transcription factor, the parameters of model can be fixed by analysis of relativity between transcription factor binding scores in promoter regions and gene expression levels. Here three relativity values should be computed while different formula is used to calculate transcription factor binding score. Relativity value A is obtained when transcription factor binding scores are calculated without considering methylation effect. Relativity value B is analyzed from transcription factor binding scores considering methylation effect with the proposed model. On the contrary, normal sigmoid function is used to depict effect of DNA methylation and relativity value C is just calculated with transcription factor binding scores considering methylation effect using such model. For a transcription factor, if relativity value B is found obviously larger than relativity value A and relativity value C is always less than relativity value A, the transcription factor can be figured out to be apparently affected by DNA methylation and the model with optimal fixed parameters can be used to depict the methylation effect. In neuroblastoma cell, with the proposed model, 10 transcriptional factors were found to be apparently affected by methylation of promoter regions which proves the effectiveness of the model. Based on the proposed model, TF binding status in genome promoter region can be presumed to further investigate how a gene is regulated by a specific group of TFs organized in a particular pattern, which should be helpful in building of gene regulation network. Moreover, if it is exactly obtained how methylation exerts quite different effect on the same TF between normal and cancer cells, the proposed method also can be used as a way to search mutant TFs which would be responsible for the cancer. But, as so many factors including DNA methylation are involved in gene transcription process and to investigate regulation mechanism of gene transcription is still a hard job.

Abstract:The diagnosis of infectious diseases, the monitoring of environment and detection of potential bioterrorism agents greatly require a pathogen identification method with better combined speed, accuracy and sensitivity. Here, a kind of novel cell-based biosensors based on measurement of fluorescence is introduced, which could detect pathogens and other antigens by measuring fluorescent signals within minutes. It is based on the specifically bind character of antigens and antibodies and the theory of bioluminescence or chemiluminescence. The cell could emit light via calcium chemically fluorescent indicators such as Fluo-4, or calcium fluorescent proteins such as aequorin, green fluorescent protein. B cell-based biosensors and mast cell-based biosensors have been applied in some fields. This kind of biosensors has advantages in combined sensitivity, accuracy and speed, while it also has disadvantages such as cross reactivity and problems with cellular storage and maintenance. This is a promising kind of biosensors applied in the diagnosis of infectious diseases, the monitoring of environment and detection of potential bioterrorism agents.