短柄五加大,小孢子发生和雌,雄配子体发育的研究

短柄五加花药５枚,每个花药四个花粉囊。小孢子母细胞减数分裂时,胞质分裂为同时型,产生正四面体形的四分体。花药壁由表皮、药室内壁、中层和绒毡层四层细胞组成,其发育类型为双子叶型。腺质绒毡层,其细胞为二核。三细胞型花粉。子房５室,每室两个胚珠,上胚珠败育,下胚珠可育。下胚珠倒生,具单珠被,厚珠心。大孢子母细胞减数分裂形成线性排列的四个大孢子,雌配子体发育属蓼型。开花当天,花粉散开,雌配子体尚未成熟,处     

Effect of selective phosphodiesterase inhibitors on response of ovine pulmonary arteries to prostaglandin E2

Gao, Yuansheng, Jean-François Tolsa, Hai Shen, and J. Usha Raj. Effect of selective phosphodiesteraseinhibitors on response of ovine pulmonary arteries to prostaglandinE₂. J. Appl. Physiol. 84(1): 13-18, 1998.Several adenosine3,5-cyclic monophosphate (cAMP)-hydrolyzingphosphodiesterase isozymes are present in the pulmonary vasculature.The present study was designed to determine the effect of selectiveinhibitors of phosphodiesterase subtypes on prostaglandinE₂(PGE₂)-induced relaxation ofisolated fourth- generation pulmonary arteries of newborn lambs.PGE₂ and forskolin causedpulmonary arteries to relax and induced an increase in theintracellular cAMP content in the vessels. The relaxation and change incAMP content were augmented by milrinone and rolipram, inhibitors ofphosphodiesterase type 3 (PDE3) and type 4 (PDE4), respectively. Theaugmentation in relaxation and the increase in cAMP content caused bymilrinone plus rolipram was greater than the sum of theresponses caused by either of the inhibitors alone.8-Methoxymethyl-1-methyl-3-(2-methylpropyl)xanthine, an inhibitor of phosphodiesterase type 1, had no effect on relaxation andchange in cAMP induced by PGE₂ andforskolin. Acetylcholine alone had no effect on cAMP content in thevessels but augmented the relaxation and the increase in cAMP inducedby PGE₂ and forskolin in arterieswith endothelium. This effect was not observed in arteries withoutendothelium or in arteries with endothelium treated withN^G-nitro-L-arginine.These results suggest that PDE3 and PDE4 are the primary enzymeshydrolyzing cAMP of pulmonary arteries of newborn lambs and that aninhibition of both PDE3 and PDE4 would result in a greater effect thanthat caused by inhibition of either one of the subtype isozymes alone.Furthermore, endothelium-derived nitric oxide may enhance cAMP-mediatedrelaxation by inhibition of PDE3.

     

Crystal structure of R22L trichosanthin

Ｔｒｉｃｈｏｓａｎｔｈｉｎ(ＴＣＳ)ｉｓａｎｉｍｐｏｒｔａｎｔｍｅｍｂｅｒｏｆｒｉｂｏｓｏｍｅｉｎａｃｔｉｖａｔｉｎｇｐｒｏｔｅｉｎｓ[1].ＩｔｐｏｓｓｅｓｓｅｓＮｇｌｙｃｏｓｉｄａｓｅａｃｔｉｖｉｔｙｒｅｍｏｖｉｎｇａｄｅｎｉｎｅ(ＡＤＥ)ａｔｐｏｓｉｔｉｏｎＡ4324ｏｆ28ＳｒＲＮＡ[2].ＴｈｅａｃｔｉｖｅｐｏｃｋｅｔｏｆＮｇｌｙｃｏｓｉｄａｓｅｈａｓｂｅｅｎｅｓｔａｂｌｉｓｈｅｄｔｈｒｏｕｇｈｔｈｅｃｒｙｓｔａｌｓｔｒｕｃｔｕｒｅｓｏｆＴＣＳ,αＭＭＣａｎｄｒｉｃｉｎａｎｄａｓｓａｙｏｆｍｕｔａｎｔｓ…     

Studies on the relation between the fast phase of millisecond delayed light emission and the proton released from oxidation of water in spinach chloroplast

The relation between the fast phase of ms-DLE (delayed light emission measured with a phosphoroscope) and the proton released from water oxidation in spinach chloroplasts was studied in several aspects. When photophosphorylation was allowed to be coupled to the Hill reaction the intensity of the fast phase of ms-DLE of chloroplast was lowered more at 1 °C than at 25 °C, and the photophosphorylation rate within 40 ms of flashing light was higher at 1 °C than at 25 °C. Adding the subunit of ATP synthase to the chloroplast preparation to block the leakage of protons through ATP synthase, the intensity of the fast phase of ms-DLE was enhanced, to a larger extent at 1 °C than at 25°C. When the ms-DLE was measured under isotonic conditions, the intensity of fast phase of ms-DLE enhanced by proton released from oxidation of water was more pronounced. The above results support the suggestion that under lower temperature and isotonic conditions, the proton released from water oxidation was liable to be localized and could enhance the intensity of the fast phase of ms-DLE more effectively.     

Excision of Ds1 from the genome of maize streak virus in response to different transposase-encoding genes

We have previously established a reverse genetic system for studying excision of the transposable element Ds1 in maize plants. Ds1 carried by the genome of maize streak virus (MSV) is introduced into maize plants by agroinfection. Excision of Ds1 from the MSV genome depends on the presence of an active Ac element in the recipient maize plants. With the purpose of exploiting MSV-Ds1 as vector for maize transformation, we studied different genes encoding the transposase (TPase) for their efficiency of activating Ds1 excision. These genes were inserted in the same T-DNA carrying MSV-Ds1 and introduced into maize plants by Agrobacterium-mediated transformation. We showed that the wild-type TPase transcribed by the 2 promoter produced much higher efficiency of Ds1 excision than that transcribed by the Ac promoter. In contrast to what had been observed in tobacco and petunia, the truncated TPase (103–807) lacking the amino-terminal 102 amino acids gave a much more reduced Ds1 excision efficiency than the wild-type TPase when both genes were transcribed by the 2 promoter.     

Discovery and structural optimization of pyrazole derivatives as novel inhibitors of Cdc25B

Structural optimization and preliminary structure–activity relationship studies of a series of N-substituted maleimide fused-pyrazole analogues with Cdc25B inhibitory activity, starting from a high-throughput screening hit, are illustrated. A simplified 3,5-diacyl pyrazole analogue was obtained as the most potent compound (118, IC₅₀ = 0.12 μM) with a 270-fold increase in potency.     

Evaluation of free radicals scavenging and immunity-modulatory activities of Purslane polysaccharides

In this study, antioxidant and immunity-modulatory activities of Purslane polysaccharide were estimated. The results revealed that in a dose-dependent manner, Purslane polysaccharides could significantly scavenge superoxide anion, 1,1-diphenyl-2-picrylhydrazyl (DPPH^?), nitric oxide and hydroxyl radicals. Furthermore, the Purslane polysaccharides could still effectively inhibit the red blood cell (RBC) haemolysis, and increase spleen, thymocyte T and B lymphocyte proliferation, it could be concluded that Purslane polysaccharides could be of considerable preventive and therapeutic significance to some free radical associated health problems such as ovarian cancer, by scavenging accumulating free radicals and enhancing immunity functions.