光周期诱导光敏感核不育水稻花药蛋白变化的研究

采用双向电脉技术对不同光周期条件下,光敏感核不育水稻（农垦５８ｓ）的可育与不育花药蛋白的变化进行分析,发现花粉发育的不同阶段中,不育花药具有四个特异蛋白ｐＩ６．２／ｂＭＷ７０ＫＤ,ｐＩ６．２／ＭＷ６８ＫＤ,ｐＩ６．２／ＭＷ３８ＫＤ和ｐＩ７．４／ＭＷ３７ＫＤ．对游离组蛋白的分析表明．长日照诱导的不育花药中游离组蛋白的相对百分率均明显低于短日照下的可育花药．据此推测长日照诱导不百花药蛋白质组成和代谢变化．不育花药中游离组蛋白含量低,可能受ＤＮＡ合成数量少的影响．     

Age-related changes in mesenchymal stem cells derived from rhesus macaque bone marrow

The regeneration potential of mesenchymal stem cells (MSCs) diminishes with advanced age and this diminished potential is associated with changes in cellular functions. This study compared MSCs isolated from the bone marrow of rhesus monkeys (rBMSCs) in three age groups: young (< 5 years), middle (8-10 years), and old (> 12 years). The effects of aging on stem cell properties and indicators of stem cell fitness such as proliferation, differentiation, circadian rhythms, stress response proteins, miRNA expression, and global histone modifications in rBMSCs were analyzed. rBMSCs demonstrated decreased capacities for proliferation and differentiation as a function of age. The production of heat shock protein 70 (HSP70) and heat shock factor 1 (HSF1) were also reduced with increasing age. The level of a core circadian protein, Rev-erb α, was significantly increased in rBMSCs from old animals. Furthermore, analysis of miRNA expression profiles revealed an up-regulation of mir-766 and mir-558 and a down-regulation of mir-let-7f, mir-125b, mir-222, mir-199-3p, mir-23a, and mir-221 in old rBMSCs compare to young rBMSCs. However, there were no significant age-related changes in the global histone modification profiles of the four histone core proteins: H2A, H2B, H3, and H4 on rBMSCs. These changes represent novel insights into the aging process and could have implications regarding the potential for autologous stem cells therapy in older patients.     

Poly(C)-Binding Protein 1, a Novel Npro-Interacting Protein Involved in Classical Swine Fever Virus Growth

N^pro is a multifunctional autoprotease unique to pestiviruses. The interacting partners of the N^pro protein of classical swine fever virus (CSFV), a swine pestivirus, have been insufficiently defined. Using a yeast two-hybrid screen, we identified poly(C)-binding protein 1 (PCBP1) as a novel interacting partner of the CSFV N^pro protein and confirmed this by coimmunoprecipitation, glutathione S-transferase (GST) pulldown, and confocal assays. Knockdown of PCBP1 by small interfering RNA suppressed CSFV growth, while overexpression of PCBP1 promoted CSFV growth. Furthermore, we showed that type I interferon was downregulated by PCBP1, as well as N^pro. Our results suggest that cellular PCBP1 positively modulates CSFV growth.     

Norovirus Genome Circularization and Efficient Replication Are Facilitated by Binding of PCBP2 and hnRNP A1

Sequences and structures within the terminal genomic regions of plus-strand RNA viruses are targets for the binding of host proteins that modulate functions such as translation, RNA replication, and encapsidation. Using murine norovirus 1 (MNV-1), we describe the presence of long-range RNA-RNA interactions that were stabilized by cellular proteins. The proteins potentially responsible for the stabilization were selected based on their ability to bind the MNV-1 genome and/or having been reported to be involved in the stabilization of RNA-RNA interactions. Cell extracts were preincubated with antibodies against the selected proteins and used for coprecipitation reactions. Extracts treated with antibodies to poly(C) binding protein 2 (PCBP2) and heterogeneous nuclear ribonucleoprotein (hnRNP) A1 significantly reduced the 5′-3′ interaction. Both PCBP2 and hnRNP A1 recombinant proteins stabilized the 5′-3′ interactions and formed ribonucleoprotein complexes with the 5′ and 3′ ends of the MNV-1 genomic RNA. Mutations within the 3′ complementary sequences (CS) that disrupt the 5′-3′-end interactions resulted in a significant reduction of the viral titer, suggesting that the integrity of the 3′-end sequence and/or the lack of complementarity with the 5′ end is important for efficient virus replication. Small interfering RNA-mediated knockdown of PCBP2 or hnRNP A1 resulted in a reduction in virus yield, confirming a role for the observed interactions in efficient viral replication. PCBP2 and hnRNP A1 induced the circularization of MNV-1 RNA, as revealed by electron microscopy. This study provides evidence that PCBP2 and hnRNP A1 bind to the 5′ and 3′ ends of the MNV-1 viral RNA and contribute to RNA circularization, playing a role in the virus life cycle.