Studies of peptide binding to allyl amine and vinyl acetic acid-modified polymers using matrix-assisted laser desorption/ionization mass spectrometry.

Previous studies have shown that increases in surface-peptide binding affinity result in decreases in peptide matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) ion signals. The present work demonstrates that, with appropriate corrections for peptide ionization efficiency under MALDI conditions, relative surface-peptide binding affinities can be assayed using the MALDI MS methodology. Peptides with a range of pI values are allowed to interact with amine-modified and carboxylic acid-modified polymer surfaces (produced by pulsed radio-frequency plasma polymerization of allyl amine and vinyl acetic acid) in buffered solutions of neutral pH. Because of the net positive and negative charges associated with the peptides and surfaces in solution, both electrostatic and hydrophilic interactions play a role in the surface-peptide interaction. Consistent with expectations, the peptide MALDI ion signals for peptides with net negative charges in solution are smaller than those for peptides with net positive charges in solution when the peptides are allowed to interact with positively charged surfaces. A reversal of the relative peptide MALDI ion signal intensities is observed when the same peptides are allowed to interact with negatively charged surfaces. Cumulatively, the results demonstrate that even modest changes in surface-peptide interactions can be comparatively probed by MALDI mass spectrometry.     

Comparative Studies on Photosynthetic Fluorescence Spectra and Fluorescence Kinetics of Bryophytes

Bryophytes are the transitional forms from water habitants to terrestrials, however, there have been only a few works on their photosynthesis. It was the first time to study on photosynthetic fluorescence spectra and fluorescence kinetics of primitive and advanced species comparatively. Both the primitive and advanced ones had the same fluorescence spectra at room temperature, which contained two maximum emissions: F_686-690 from the Photosystem II and F_736-740 from the Photosystem I. And then, there were three maximum emissions in the fluorescence spectra at 77K :F_687-689 and F_697-699 from Photosystem II, and F_723-734 from Photosystem I. The first two maximum emissions were the same for both the primitive and advanced species. According to the third maximum emission the bryophytes under study fell into two categories: The first one possessing the maximum emission around 725 nm, including Ditrichum flexicaule , Didymodon icmadophyllum , Didymodon rigidicaulis, Aloina obliquifolia, Plagiomnium confertidens and Marchantia polymorpha, which were primitive mosses and advanced liverwort. The second one possessing the maximum emission around 732nm, including Thuidium delicatulum , Pylaisia brotheri , Myuroclada maximowiczii , Taxiphyllum taxirameum, Gollania neckerella, Eurohypnum leptothallum, which were advanced mosses, and the primitive one Plagiomnium rostratum. The characteristics of fluorescence spectra implied that the Photosystem II was conservative and Photosystem I was changeable during bryophyte evolution. The primitive mosses possess mainly the PSI core complex (CPI) and then the advanced species contain both CPI and LHC-I. In analysis of photosynthetic fluorescence kinetics, Fv/(Fc+Fv) is a measure of the activity of the Photosystem II; Fv/Fm is dependent on efficiency of primary photoconversion in the Photosystem II; Fm/(Fo+Fv) is related to photosynthetic carbon assimilation; and Fd/Fs is a measure of the potential photosynthetic quantum conversion. The fluorescence kinetics of the bryophyte photosynthesis showed that the Photosystem II activity, the efficieiency of primary photoconversion in Photosystem II, the photosynthetic carbon assimilation and the efficiency of the potential photosynthetic quantum conversion in primitive species, such as Ditrichum flexicaule, Didymodon icmadophyllus, D. rigidicaulis, Plagiomnium rostratum and the liverwort Marchantia polymorpha, were lower than those in the advanced species, Myuroclada maximowiczii, Pylaisia brotheri , Gollania neckerella Taxiphyllum taxirameum , Thuidium delicatulum. However, the primitive Plagiomnium confertidens was of the high activities and efficiencies and the advanced Eurohypnum leptothallum was of low ones. It seemed that P. confertidens and E. leptothallum were an intermediatefrom the primitive to the advanced.     

Embryo Sacs of Hevea brasiliensis and Carica papaya Isolated with Enzyme-Squash Technique

The enzyme-squash technique had been employed to study the development of megaspores and embryo sacs from tropical plants of Hevea brasiliensis Muel-Arg. and Carica papaya L. Ovules fixed with FAA or FPA were enzymatieally macerated in 3% pectinase cellulase solution or in 3–4% snailase solution for 4–6 h, at 28–30℃ to isolate the embryo sacs after being squashed. The whole structural images of megaspores and embryo sacs at different developmental stages were observed and identified without staining under Olympus BH-2 phase contrast microscope or light microscope after ron-aceto-carmine staining.     

Structures of Sarcorucinine D and Pachyaximine A,B

In this paper, three new alkaloids, sarcorucinine D (1), and paehyaximine A, B (2, 3) were isolated from Sarcococca ruscifolia Stapf and Pachysandra axillaris Franch, respectively. The structures of sarcorucinine D (1) and pachyaximine A, B (2, 3) were elucidated to be 3β-hydroxyl-20α-dimethylamino-5α-pregnane (1); and 3β-methoxyl-20α-dimethylamino-pregne-5-ne (2); and 3β-methoxyl-16-hydroxyl-20α-dimethylaminopregne-5-ne (16-hydroxyl-pachyaxi- mine A) (3), respectively.     

Studies on the Constituents from Marsdenia globifera

Two novel C-21 steroidal aglycones named marsglogenin-A(Ⅱ) and marsglogenin-B(Ⅲ) as well as six known compounds sarcostin (Ⅰ), gymnemarsgenin (Ⅳ), 20-O-cinnamoylsarcostin (Ⅴ), penupogenin (Ⅵ), gagaminin (Ⅶ) and isolineolcn (Ⅷ) were isolated from the acid hydrolysate of the crude glycoside extracted with ethanol from the stem of Marsdenia globitera (Asclepiadaceae). The structures of marsglogenin-A and marsglogenin-B were deduced as 20-O-benzoylsarcostin and 12-O-benzoylsarcostin on the bases of chemical and spectral evidences respectively.     

Three New Steroidal Alkaloids from Pachysandra axillaris

This paper describes the chemical structure elucidation of the three new alkaloids isolated from Pachysandra axillarls Franch. They are pachysamine G (20α-dimethylamino-3β-tigloylamino-5α-pregnane), pachysamine H (20α-dimethylamino-3α-N-methyl, benzoylamino-5α-pregnane) and pachysanaximine A (20 α-dimethylamino-3β-methylamino-4β-benzoxyl-5α-pregnane) respectively. Other two compounds were identified as Pachysamine A, B.     

山西省管涔山林区苔藓植物垂直带的研究

本文根据山西省管涔山林区苔藓植物特有种及优势种, 并参考环境特征, 将苔藓植物垂直带划分为:低山苔藓植物带, 针叶林区苔藓植物带、亚高山灌丛草甸区苔藓植物带。     

Two New Buxus Alkaloids from Buxus Microphylla Sieb. et Zucc.

Five compounds were isolated from Buxus microphylla Sieb. et Zucc. Based on the physico-chemical constants and spectral analysis (IR, MS, 1H-NMR and 13C-NMR), they were identified as cycloprotobuxinamine ( Ⅰ ), buxmicrophylline A ( Ⅱ ), buxtauine M ( Ⅲ ), isoscopoletin (Ⅳ) and epi-lupeol ( Ⅴ ). ( Ⅰ ) and ( Ⅱ ) were new compounds. The structure of buxmicrophylline ( Ⅱ ) was confirmed by X-ray crystallographic analysis.     

The Ultrastructural Study on the Early Embryonic Development of Radish

The ultrastructure of the mature embryo sac, the early stages of the embryo and endosperm development of common radish, Raphanur sativus was examined. The embryo sac consists of 7 cells with antipodal ceils disappeared when it matures. The egg cell is highly polarized. The wall surrounded the chalazal end of the egg cell is incomplete, showing a discontinuous structure of an electron dense material deposited intermittently in the space between the two plasma membranes of the egg cell and central cell. The synergid has filiform apparatus, rich in organelles and well developed ER. The two polar nuclei of the central cell are located near the egg apparatus because of the big vacuole, and the finger-like protrutions from the cell wall, as that in synergid, are found. The first division of the zygote occurs 4–5 days after pollination and the development of the embryo follows the Onagrad type, and the structure of the embryo cell is quite simple for containing small quantity of ER, plastids and other organelles. The primary endosperm nucleus deviates 2 days earlier than zygote. The endosperm is of nuclear-endosperm containing chloroplasts, well developed ER, and plentiful of mitochondria and golgi bodies and the nodule-like aggregation in both. the chalazal and micropylar ends of the embryo sac during the early development appeared, and cell wall starting at the micropylar end by freely-growing forms about 16 days after pollination.