北京地区均翅亚目昆虫的生态分布

调查发现北京地区现分布蜻蜓目均翅亚目昆虫 3科 1 0种 ,其中科的蓝纹与二色异痣为优势种 ,分布最为广泛 ,通过主成分分析 ,湿地内的浮水层植物盖度、挺水层植物盖度、周围植被盖度及沉水层植物盖度是影响它们分布的最主要生态因子 ,各因子的贡献率分别为 3 0 49,2 4 1 4,1 7 45和1 5 2 6%。色科黑色和透顶单脉色主要分布于北京西南部地区及北部山区水流较快、水体较浅、污染度较小的水域。长叶异痣、七条和白扇主要分布在河流和水库湖泊的边缘地带 ,数量相对较少。烟翅绿色、红痣绿色及白狭扇仅在山区发现 ,分布范围较为狭窄。     

Characterization of senescence-associated proteases in postharvest broccoli florets.

We characterized the senescence-associated proteases of postharvest broccoli (Brassica oleracea L. var Green King) florets, using class-specific protease inhibitors and gelatin-polyacrylamide gel electrophoresis. Different classes of senescence-associated proteases in broccoli florets were partially characterized for the first time. Protease activity of broccoli florets was depressed by all the inhibitors and showed different inhibition curves during postharvest. The hydrolytic activity of metalloprotease (EC 3.4.24. - ) and serine protease (EC 3.4.21. - ) reached a maximum, 1 day after harvest (DAH), then decreased, while the hydrolytic activity of cysteine protease (EC 3.4.22. - ) and aspartic protease (EC 3.4.23. - ) increased throughout the postharvest senescence based on the calculated inhibition percentage of protease activity. The senescence-associated proteases were separated into seven endoprotease (EP) groups by gelatin-polyacryamide gel electrophoresis and classified into EP1 (metalloprotease), EP2 (metalloprotease and cysteine protease), EP3 (serine protease and aspartic protease), EP4, EP5, EP7 (cysteine protease), and EP6 (serine protease) based on the sensitivity of class-specific protease inhibitors. The proteases EP2, EP3, and EP4 were present throughout the postharvest stages. EP3 was the major EP at all times during senescence; EP4 intensity of activity increased after 2 DAH; EP6 and EP7 clearly increased after 4 DAH. Our results suggest that serine protease activity contributes to early stage (0-1 DAH) and late stage (4-5 DAH) of senescence; metalloprotease activity was involved in the early and intermediate stages (0-3 DAH) of senescence; and cysteine protease and aspartic protease activities participated in the whole process of broccoli senescence.     

Progression through meiosis I and meiosis II in Arabidopsis anthers is regulated by an A-type cyclin predominately expressed in prophase I

Meiosis is often described as a special case of cell division since it differs from mitosis in having two nuclear divisions without an intervening S-phase. It will be of great interest to uncover what molecular mechanisms underlie these special features of meiosis. We previously reported that the tardy asynchronous meiosis (tam) mutant of Arabidopsis (Arabidopsis thaliana) is slower in cell cycle progression in male meiosis. Here we report that TAM encodes the A-type cyclin, CYCA1;2. The point mutation in tam replaced a conserved threonine with an isoleucine in the linker region between the alpha4 and alpha5 helices of the first cyclin fold. By studying the dynamics of a CYCA1;2-green fluorescent protein fusion protein under the control of the CYCA1;2 promoter, we found that the fusion protein was most abundant at pachytene, but was undetectable from late prophase I until telophase II. Nonetheless, cell cycle progression in tam was delayed in both pachytene and meiosis II. We conclude either that the CYCA1;2 produced in prophase I indirectly regulates meiosis II progression, or that a very low level of CYCA1;2 directly regulates meiosis II progression. Either of these scenarios is a deviation from the typical mode of action of mitotic cyclins in mitosis and meiosis I, in which each nuclear division is coupled with a peak of expression of mitotic cyclins.     

Isolation, characterization and expression analysis of a leaf-specific phosphoenolpyruvate carboxylase gene in Oryza sativa.

Suppression subtractive hybridization was carried out to enrich gene fragments over-expressed in rice leaves by subtraction to rice roots, from which two identical cDNA fragments were identified to encode putative phosphoenolpyruvate carboxylase. Then the corresponding full-length cDNA (Osppc) is isolated by RT-PCR and sequenced, which indicates an open reading frame of 2895bp is contained. Its deduced protein is encoded in 10 exons and shows high similarity to many other plant PEPCs. Comparing with maize and bacterial PEPCs, it is revealed that OSPPC shares many conserved domains and active sites that responsible for the structure, activity and regulation of this enzyme. Phylogenetic analysis demonstrates that OSPPC is grouped with C3 form PEPCs of wheat, maize and sorghum, which is consistent with the classification of rice. And a putative promoter element is predicted with DOF binding box, CAAT box and TATA box in the 5'-flanking sequence of Osppc gene. Moreover, Quantitative RT-PCR analyses are performed in hybrid rice and its parents, which show that Osppc is specifically expressed in leaf including leaf vein and sheath.     

Indene bioconversion by a toluene inducible dioxygenase of Rhodococcus sp. I24

Rhodococcus sp. I24 can oxygenate indene via at least three independent enzyme activities: (i) a naphthalene inducible monooxygenase (ii) a naphthalene inducible dioxygenase, and (iii) a toluene inducible dioxygenase (TID). Pulsed field gel analysis revealed that the I24 strain harbors two megaplasmids of 340 and 50 kb. Rhodococcus sp. KY1, a derivative of the I24 strain, lacks the 340 kb element as well as the TID activity. Southern blotting and sequence analysis of an indigogenic, I24-derived cosmid suggested that an operon encoding a TID resides on the 340 kb element. Expression of the tid operon was induced by toluene but not by naphthalene. In contrast, naphthalene did induce expression of the nid operon, encoding the naphthalene dioxygenase in I24. Cell free protein extracts of Escherichia coli cells expressing tidABCD were used in HPLC-based enzyme assays to characterize the indene bioconversion of TID in vitro. In addition to 1-indenol, indene was transformed to cis-indandiol with an enantiomeric excess of 45.2% of cis-(1S,2R)-indandiol over cis-(1R,2S)-indandiol, as revealed by chiral HPLC analysis. The K_m of TID for indene was 380 M. The enzyme also dioxygenated naphthalene to cis-dihydronaphthalenediol with an activity of 78% compared to the formation of cis-indandiol from indene. The K_m of TID for naphthalene was 28 M. TID converted only trace amounts of toluene to 1,2-dihydro-3-methylcatechol after prolonged incubation time. The results indicate the role of the tid operon in the bioconversion of indene to 1-indenol and cis-(1S,2R)-indandiol by Rhodococcus sp. I24.     

Participation of PI3K and ERK1/2 pathways are required for human brain vascular smooth muscle cell migration

Human brain vascular smooth muscle cell (HBVSMC) migration contributes to angiogenesis and several pathological processes in the brain. However, the molecular mechanism of angiogenesis, in which smooth muscle cell contributes, remains unclear. Our study investigates the role of vascular endothelial growth factor (VEGF) in the HBVSMC migration and elucidates the chemotactic signaling pathway mediating this action. We used the in vitro 'scratch' wound method to detect the HBVSMC migration. VEGF(165) (1-40ng/ml) induced the HBVSMC migration in a dose-dependent manner (P<0.05). VEGF(165) does not induce HBVSMC proliferation. Wortmannin, a specific phosphatidylinositol 3-kinase (PI3K) inhibitor, significantly inhibited serine/threonine kinase Akt/protein kinase B (PKB) phosphorylation and reduced HBVSMC migration into the wound edge following VEGF(165) stimulation (P<0.05). PD98059, an extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor, also significantly inhibited ERK1/2 phosphorylation and reduced the numbers of SMC migration. Parallel distance measurement showed that VEGF(165) induced HBVSMC migration significantly reduced due to inhibition of PI3K or ERK1/2 phosphorylation (P<0.05). Our results demonstrate that VEGF(165) could induce HBVSMC migration but not proliferation in vitro. Inhibiting Akt/PKB or ERK1/2 phosphorylation could reduce VEGF(165) induced HBVSMC migration. We provide the first evidence that activation of PI3K or ERK1/2 pathways are a crucial event in VEGF(165) mediated signal transduction leading to HBVSMC migration.     

Fulvic acid disturbs processing of procollagen II in articular cartilage of embryonic chicken and may also cause Kashin-Beck disease.

Kashin-Beck disease is an endemic osteoarthropathy in China which may lead to skeletal deformation and dwarfism. We have analysed articular cartilage from two patients and found an accumulation of the precursor molecule, pro-pN-collagen II (pN, peptide attached at the amino-terminus) which was not present in extracts of control fetal cartilage. In addition, collagen II isolated from the same tissue by limited pepsin digestion had a decreased electrophoretic mobility, increased proline hydroxylation and decreased thermal stability. Previously, a genetic defect in pro-pN-collagen-I processing has been described in calf and sheep (dermatosparaxis) and man (Ehlers-Danlos, type VII) which caused an extreme fragility of the skin [Lenaers, A., Ansay, M., Nusgens, B.V. & Lapière, C.M. (1971) Eur. J. Biochem. 23, 533-541; Helle, O. & Nes, N.J. (1972) Acta Vet. Scand. 13, 443-445; Lichtenstein, J.R., Martin, G.R., Kohn, L.D., Byers, P.H. & McKusick, V.A. (1973) Science 182, 298-300]. Accordingly, one may assume that the impaired conversion of pro-pN-collagen II to collagen II and the structural alteration of collagen II, presumably caused by fulvic acid and other environmental factors, play an important role in the pathogenesis of Kashin-Beck disease.     

稻田生物群落的能流参数

为了从能流动态来研究稻田生物群落,本文用田间调查和实验室测定等方法,取得了晚稻田生物群落的物种数量、生物量、热值、呼吸量、生产力、同化效率、摄食量等数据。据此,进一步估算了晚稻田生物群落的能量流动参数。根据其能量收支,用能量金字塔总结了晚稻田生物群落各类种群间的能量关系。