罗布麻资源利用与罗布麻植物分类问题

叙述了有关罗布麻分类的简要历史,讨论了我国罗布麻的植物分类问题,从植物分类学的依据和生产实践的需要考虑,应将我国罗布麻植物划分为1属2种,即罗布麻属（Apocynum L．）和罗布红麻（A．venetum L．）及罗布白麻（A．hendersonii Hook．f．）2种。     

茶树鲜花饮料澄清技术研究

茶树鲜花与茶叶具有相似的营养成分,榨汁后经调配可开发成适口性好、风味独特的鲜花饮料。对茶树鲜花饮料的壳聚糖絮凝、酶法澄清、超滤澄清效果进行了比较,结果表明,采用10万分子截留量的超滤膜处理获得能够较好的澄清效果,且对茶多酚造成的操作损失较小。     

Diversity of centromeric repeats in two closely related wild rice species, Oryza officinalis and Oryza rhizomatis

Oryza officinalis (CC, 2n=24) and Oryza rhizomatis (CC, 2n=24) belong to the Oryza genus, which contains more than 20 identified wild rice species. Although much has been known about the molecular composition and organization of centromeres in Oryza sativa, relatively little is known of its wild relatives. In the present study, we isolated and characterized a 126-bp centromeric satellite (CentO-C) from three bacterial artificial chromosomes of O. officinalis. In addition to CentO-C, low abundance of CentO satellites is also present in O. officinalis. In order to determine the chromosomal locations and distributions of CentO-C (126-bp), CentO (155 bp) and TrsC (366 bp) satellite within O. officinalis, fluorescence in situ hybridization examination was done on pachytene or metaphase I chromosomes. We found that only ten centromeres (excluding centromere 7 and 2) contain CentO-C arrays in O. officinalis, while centromere 7 comprises CentO satellites, and centromere 2 is devoid of any detectable satellites. For TrsC satellites, it was detected at multiple subtelomeric regions in O. officinalis, however, in O. rhizomatis, TrsC sequences were detected both in the four centromeric regions (CEN 3, 4, 10, 11) and the multiple subtelomeric regions. Therefore, these data reveal the evolutionary diversification pattern of centromere DNA within/or between close related species, and could provide an insight into the dynamic evolutionary processes of rice centromere.     

Biomimetic zinc oxide replica with structural color using butterfly (Ideopsis similis) wings as templates

Nano-structured colorful zinc oxide (ZnO) replicas were produced using the wings of the Ideopsis similis butterfly as templates. The ZnO replicas we obtained exhibit iridescence, which was clearly observed under an optical microscope (OM). Field emission scanning electron microscope analysis shows that all the microstructure details are maintained faithfully in the ZnO replica. A computer model was established to simulate the diffraction spectral results, which agreed well with the OM images.     

Mechanical loading stimulates expression of connexin 43 in alveolar bone cells in the tooth movement model

Bone osteoblasts and osteocytes express large amounts of connexin (Cx) 43, the component of gap junctions and hemichannels. Previous studies have shown that these channels play important roles in regulating biological functions in response to mechanical loading. Here, we characterized the distribution of mRNA and protein of Cx43 in mechanical loading model of tooth movement. The locations of bone formation and resorption have been well defined in this model, which provides unique experimental systems for better understanding of potential roles of Cx43 in bone formation and remodeling under mechanical stimulation. We found that mechanical loading increased Cx43 mRNA expression in osteoblasts and bone lining cells, but not in osteocytes, at both formation and resorption sites. Cx43 protein, however, increased in both osteoblasts and osteocytes in response to loading. Interestingly, the upregulation of Cx43 protein by loading was even more pronounced in osteocytes compared to other bone cells, with an appearance of punctate staining on the cell body and dendritic process. Cx45 was reported to be expressed in several bone cell lines, but here we did not detect the Cx45 protein in the alveolar bone cells. These results further suggest the potential involvement of Cx43-forming gap junctions and hemichannels in the process of mechanically induced bone formation and resorption.     

Conditional expression of Smad7 in pancreatic beta cells disrupts TGF-beta signaling and induces reversible diabetes mellitus

Identification of signaling pathways that maintain and promote adult pancreatic islet functions will accelerate our understanding of organogenesis and improve strategies for treating diseases like diabetes mellitus. Previous work has implicated transforming growth factor-beta (TGF-beta) signaling as an important regulator of pancreatic islet development, but has not established whether this signaling pathway is required for essential islet functions in the adult pancreas. Here we describe a conditional system for expressing Smad7, a potent inhibitor of TGF-beta signaling, to identify distinct roles for this pathway in adult and embryonic beta cells. Smad7 expression in Pdx1+ embryonic pancreas cells resulted in striking embryonic beta cell hypoplasia and neonatal lethality. Conditional expression of Smad7 in adult Pdx1+ cells reduced detectable beta cell expression of MafA, menin, and other factors that regulate beta cell function. Reduced pancreatic insulin content and hypoinsulinemia produced overt diabetes that was fully reversed upon resumption of islet TGF-beta signaling. Thus, our studies reveal that TGF-beta signaling is crucial for establishing and maintaining defining features of mature pancreatic beta cells.     

Structural analysis of a rhomboid family intramembrane protease reveals a gating mechanism for substrate entry

Intramembrane proteolysis regulates diverse biological processes. Cleavage of substrate peptide bonds within the membrane bilayer is catalyzed by integral membrane proteases. Here we report the crystal structure of the transmembrane core domain of GlpG, a rhomboid-family intramembrane serine protease from Escherichia coli. The protein contains six transmembrane helices, with the catalytic Ser201 located at the N terminus of helix alpha4 approximately 10 A below the membrane surface. Access to water molecules is provided by a central cavity that opens to the extracellular region and converges on Ser201. One of the two GlpG molecules in the asymmetric unit has an open conformation at the active site, with the transmembrane helix alpha5 bent away from the rest of the molecule. Structural analysis suggests that substrate entry to the active site is probably gated by the movement of helix alpha5.     

“A simple and rapid method for isolating lichen photobionts“

For decades, lichenologists have developed numerous and varied methods to isolate lichen photobionts. Most procedures are tedious, slow, and require several months after the initial isolation to obtain clones. Furthermore, the purity of the isolated photobionts obtained by more rapid methods is not sufficient to establish phycobiont axenic cultures. We have developed a new method for isolating lichen photobionts from fruticose, foliose and crustose lichens. Basically, it involves homogenization of lichen thalli (from 15 mg to 2 g), a one-step centrifugation through Percoll ®, followed by washing with Tween 20 and sonication. With this simple and rapid method (which takes less than 2 h), photobiont cells are obtained in sufficient quantity and purity to obtain dozens of axenic algal cultures.     

Isolation and characterization of enantioselective DNA aptamers for ibuprofen

Single stranded DNA aptamers that can bind to ibuprofen, a widely used anti-inflammation drug, were selected from random DNA library of 10¹⁵ nucleotides by FluMag-SELEX process. Five different sequences were selected and their enantioselectivity and affinity were characterized. Three out of five aptamer candidates did not show any affinity to (S)-ibuprofen, but only to racemic form of ibuprofen, suggesting that they are (R)-ibuprofen specific aptamers. Another two aptamer candidates showed affinity to both racemic form and (S)-ibuprofen, which were considered as (S)-ibuprofen specific aptamers. The affinity of five ssDNA aptamers isolated was in a range of 1.5–5.2 μM. In addition, all of these five aptamers did not show any affinity to analogues of ibuprofen in its profen’s group (fenoprofen, flubiprofen, and naproxen) and the antibiotics of oxytetracycline, another control.     

褪黑素对胃癌小鼠Survivin表达的影响

目的探讨褪黑素对胃癌小鼠Survivin表达的影响。方法选用6-8周龄SPF级615近交系小鼠,接种胃癌MFC细胞,建立荷瘤小鼠模型并给予不同剂量的褪黑素处理,用Real-time PCR法和Western blot法检测肿瘤组织中Survivin mRNA和蛋白的表达。结果 Real-time PCR和Western-blot检测显示褪黑素各干预组小鼠胃癌组织中Survivin基因的表达水平下降且随褪黑素剂量增大而降低。结论褪黑素具有下调survivin的作用。褪黑素降低survivin的表达,可能是褪黑素抑制肿瘤的作用机制之一。