cDNA cloning and overexpression of acidic ribosomal phosphoprotein P1 gene (RPLP1) from the Giant Panda

RPLP1 is one of acidic ribosomal phosphoproteins encoded by RPLP1 gene, which plays an important role in the elongation step of protein synthesis. The cDNA of RPLP1 was cloned successfully for the first time from the Giant Panda (Ailuropoda melanoleuca) using RT-PCR technology, which was also sequenced, analyzed preliminarily and expressed in E. coli. The cDNA fragment cloned is 449bp in size, containing an open reading frame of 344bp encoding 114 amino acids. Alignment analysis indicated that the nucleotide sequence and the deduced amino acid sequence are highly conserved to other five species studied, including Homo sapiens, Mus musculus, Rattus norvegicus, Bos Taurus and Sus scrofa. The homologies for nucleotide sequences of Giant Panda PPLP1 to that of these species are 92.4%, 89.8%, 89.0%, 91.3% and 87.5%, while the homologies for amino acid sequences are 96.5%, 94.7%, 95.6%, 96.5% and 88.6%. Topology prediction showed there are three Casein kinase II phosphorylation sites and two N-myristoylation sites in the RPLP1 protein of the Giant Panda (Ailuropoda melanoleuca). The RPLP1 gene was overexpressed in E. coli and the result indicated that RPLP1 fusion with the N-terminally His-tagged form gave rise to the accumulation of an expected 18kDa polypeptide, which was in accordance with the predicted protein and could also be used to purify the protein and study its function.

胚胎期光照和皮质酮对小鸡记忆影响的作用机制

It has been shown that prenatal light exposure and corticosterone improve memory retention of dark hatched chicks. The object of this study was to explore the neural mechanisms underlying the effect of prenatal light exposure and corticosterone on memory retention of chicks. To detect the effect of different prenatal treatments on memory retention of chicks, we used one-trial passive avoidance model. To examine the expression of glucocorticoid receptor (GR), neural cell adhesion molecule (NCAM), growth-associated protein 43 (GAP-43) and polysialic acid (PSA) in HV and LPO of chick brain, we used immunohistochemical method. Prenatal light exposure and glucocorticoid (corticosterone, dexamthesone) administered in embryonic day 20 (E20) markedly improve memory retention in dark hatched chicks. Light plays a critical role in improving memory. The critical exposure period is E19 and E20. The effect of these two hormones and light exposure can be significantly blocked by their receptor antagonist administration respectively. The light, corticosterone and particularly darkness significantly up-regulated the level of GR; the expression of NCAM and GAP-43 in HV and LPO peaked in E20 in normal hatched chicks and was significantly increased by light exposure and corticosterone. Protein synthesis inhibitor anisomycin markedly reduced the effect of light exposure but partially reduced the effect of corticosterone; light exposure and corticosterone in E20 significantly up-regulated PSA expression. Removing PSA from NCAM significantly retarded the effect of corticosterone on memory retention in chicks. Therefore, The effects of prenatal light exposure and corticosterone on memory retention are mediated via both corticosteroid receptors. The effects of both prenatal light and corticosterone might at first change the plasticity of the brain by up-regulation the synthesis and modification of proteins, and then influence the behavior performance of the chicks.

Synthesis, characterization, and self-assembly of protein lysozyme monolayer-stabilized gold nanoparticles

Lysozyme monolayer-protected gold nanoparticles (Au NPs) which are hydrophilic and biocompatible and show excellent colloidal stability at low temperature, ca. 4 degrees C, were synthesized in aqueous medium by chemical reduction of HAuCl4 with NaBH4 in the presence of a familiar small enzyme, lysozyme. UV-vis spectra, transmission electron microscopy (TEM), atomic force microscopy, and X-ray photoelectron spectroscopy characterization of the as prepared nanoparticles revealed the formation of well-dispersed An NPs of ca. 2 nm diameter. Moreover, the color change of the An NP solution as well as UV-vis spectroscopy and TEM measurements have also demonstrated the occurrence of Ostwald ripening of the nanoparticles at low temperature. Further characterization with Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering indicated the formation of a monolayer of lysozyme molecules on the particle surface. FTIR data also indicated the intactness of the protein molecules coated on An NPs. All the characterization results showed that the monodisperse An NPs are well-coated directly with lysozyme. Driven by the dipole-dipole attraction, the protein-stabilized Au NPs self-assembled into network structures and nanowires upon aging under ambient temperature.