Effects of transdifferentiation and EGF on claudin isoform expression in alveolar epithelial cells.

Rat alveolar epithelial type II cells grown on polycarbonate filters form high-resistance monolayers and concurrently acquire many phenotypic properties of type I cells. Treatment with EGF has previously been shown to increase transepithelial resistance across alveolar epithelial cell (AEC) monolayers. We investigated changes in claudin expression in primary cultured AEC during transdifferentiation to the type I cell-like phenotype (days 0, 1, and 8), and on day 5 in culture +/- EGF (10 ng/ml) from day 0 or day 4. Claudins 4 and 7 were increased, whereas claudins 3 and 5 were decreased, on later compared with earlier days in culture. Exposure to EGF led to increases in claudins 4 and 7 and decreases in claudins 3 and 5. Claudin 1 was only faintly detectable in freshly isolated type II cells and remained unchanged over time in culture and after exposure to EGF. These results suggest that increases in transepithelial resistance accompanying AEC transdifferentiation and/or EGF exposure are mediated, at least in part, by changes in the pattern of expression of specific claudin isoforms.     

清香桂碱D和矮陀陀胺碱A,B的结构

本文报道从国产清香桂(Sarcococca ruscifolta)和金丝矮陀陀(Pachysandra axillaria)植物中分得的三个胺碱型新甾体生物碱清香桂碱 D 和矮陀陀胺碱 A、B 的化学结构,并首次归属了它们的~(13)C NMR 数据。     

广东鹤山南亚热带丘陵人工林昆虫资源的研究(Ⅱ)

本文根据2001和2002年的调查结果,记述了广东鹤山南亚热带丘陵退化生态系统恢复中四种人工林的昆虫种类,共计14目161科488种,本文记载3目77科272种.     

Gastric inhibitory polypeptide modulates adiposity and fat oxidation under diminished insulin action

Gut hormone gastric inhibitory polypeptide (GIP) stimulates insulin secretion from pancreatic β-cells upon ingestion of nutrients. Inhibition of GIP signaling prevents the onset of obesity and consequent insulin resistance induced by high-fat diet. In this study, we investigated the role of GIP in accumulation of triglycerides into adipocytes and in fat oxidation peripherally using insulin receptor substrate (IRS)-1-deficient mice and revealed that IRS-1^−/−GIPR^−/− mice exhibited both reduced adiposity and ameliorated insulin resistance. Furthermore, increased gene expression of CD36 and UCP2 in liver, and increased expression and enzyme activity of 3-hydroxyacyl-CoA dehydrogenase in skeletal muscle of IRS-1^−/−GIPR^−/− mice might contribute to the lower respiratory quotient and the higher fat oxidation in light phase. These results suggest that GIP plays a crucial role in switching from fat oxidation to fat accumulation under the diminished insulin action as a potential target for secondary prevention of insulin resistance.     

Cloning and characterization of a non-TIR-NBS-LRR type disease resistance gene analogue from peach.

Cloning of plant disease resistant genes is greatly helpful for disease resistant breeding in plants and the insight of resistance mechanism. However, there are less relevant researches in peach [prunus persica (L.) Batch]. In this study, four NBS-LRR type resistance gene analogs (RGAs) were cloned from genomic DNA of peach. The PNBS2 fragment was also amplified from peach cDNA and the full-length cDNA of PNBS2 (PRPM1, GenBank accession no. AY599223) has been cloned. Sequence analysis indicated that the cDNA of PRPM1 is 3007 bp in length and that the contained ORF encodes for a polypeptide of 917 amino acids. Compared with known NBS-LRR genes, it presented relatively high amino acid sequence identity. The polypeptide has typical structure of non-TIR-NBS-LRR genes, with NB-ARC, LZ, LRR and transmembrane domains. Southern analysis indicated that the PRPM1 gene might be a single copy in peach genome. Northern blot and RT-PCR analysis showed that the expression of PRPM1 was not induced by salicylic acid (SA) in peach young leaves. The isolation of putative resistance genes from peach provided useful bases for studying the structure and function of peach disease-resistance relating genes and disease resistant genetic breeding in peach.     

Gene cluster responsible for validamycin biosynthesis in Streptomyces hygroscopicus subsp. jinggangensis 5008

A gene cluster responsible for the biosynthesis of validamycin, an aminocyclitol antibiotic widely used as a control agent for sheath blight disease of rice plants, was identified from Streptomyces hygroscopicus subsp. jinggangensis 5008 using heterologous probe acbC, a gene involved in the cyclization of D-sedoheptulose 7-phosphate to 2-epi-5-epi-valiolone of the acarbose biosynthetic gene cluster originated from Actinoplanes sp. strain SE50/110. Deletion of a 30-kb DNA fragment from this cluster in the chromosome resulted in loss of validamycin production, confirming a direct involvement of the gene cluster in the biosynthesis of this important plant protectant. A sequenced 6-kb fragment contained valA (an acbC homologue encoding a putative cyclase) as well as two additional complete open reading frames (valB and valC, encoding a putative adenyltransferase and a kinase, respectively), which are organized as an operon. The function of ValA was genetically demonstrated to be essential for validamycin production and biochemically shown to be responsible specifically for the cyclization of D-sedoheptulose 7-phosphate to 2-epi-5-epi-valiolone in vitro using the ValA protein heterologously overexpressed in E. coli. The information obtained should pave the way for further detailed analysis of the complete biosynthetic pathway, which would lead to a complete understanding of validamycin biosynthesis.     

Computer vision-assisted photogrammetry and one-image 3D modeling in marine mammals

Image processing using traditional photogrammetric methods is a labor-intensive process. The collection of photogrammetry images during aerial surveys is expanding rapidly, creating new challenges to analyze images promptly and efficiently, while reducing human error during processing. Computer vision-assisted photogrammetry, a field of artificial intelligence (AI), can automate image processing, greatly enhancing the efficiency of photogrammetry. Here, we present a practical and efficient program capable of automatically extracting the fine-scale photogrammetry of East Asian finless porpoises (Neophocaena asiaeorientalis sunameri). Our results indicated that computer vision-assisted photogrammetry could achieve the same accuracy as traditional photogrammetry, and the results of the comparisons were validated against the direct measurements. Three-dimensional (3D) models using computer vision-assisted photogrammetric morphometrics generated trustworthy body volume estimates. We also explored the one image-based 3D modeling technique, which is less accurate, but still useful when only one image of the animal is available. Although several limitations exist in the current program, improvements could be made to narrow the virtual-reality gap when more images are available for machine learning and training. We recommend this program for analyzing images of marine mammals possessing a similar morphological contour.     

Systematic high-yield production of human secreted proteins in Escherichia coli

Human secreted proteins play a very important role in signal transduction. In order to study all potential secreted proteins identified from the human genome sequence, systematic production of large amounts of biologically active secreted proteins is a prerequisite. We selected 25 novel genes as a trial case for establishing a reliable expression system to produce active human secreted proteins in Escherichia coli. Expression of proteins with or without signal peptides was examined and compared in E. coli strains. The results indicated that deletion of signal peptides, to a certain extent, can improve the expression of these proteins and their solubilities. More importantly, under expression conditions such as induction temperature, N-terminus fusion peptides need to be optimized in order to express adequate amounts of soluble proteins. These recombinant proteins were characterized as well-folded proteins. This system enables us to rapidly obtain soluble and highly purified human secreted proteins for further functional studies.     

Numb proteins specify asymmetric cell fates via an endocytosis- and proteasome-independent pathway

Numb proteins are evolutionarily conserved signaling molecules that make the daughter cells different after asymmetric divisions by segregating to only one daughter. They contain distinct binding motifs for alpha-adaptin (alpha-Ada) and proteins with Eps15 homology (EH) domains, which regulate endocytosis, and for E3 ubiquitin ligases, which target proteins for proteasome-mediated degradation. In Drosophila melanogaster, Numb acts by inhibiting Notch activity to cause a bias in Notch-mediated cell-cell communication. These findings have led to the hypothesis that Numb modulates Notch signaling by using endocytosis and proteasomes to directly reduce Notch protein levels at the cell surface. Here we show that two Drosophila EH proteins, Eps15 homologue 1 (EH1) and the dynamin-associated 160-kDa protein (Dap160), negatively regulate Notch signaling. However, neither elimination of the binding motifs for endocytic proteins nor simultaneous reduction of proteasome activity affects the activity of Numb proteins. Our findings indicate that an endocytosis- and proteasome-independent pathway may mediate Numb signaling in asymmetric cell fate specification.