Isolation and nomenclature of pigment-protein complexes from the brown alga (Undaria pinnatifida Harv.)

Eight kinds of pigment-protein complexes were resolved from the thylakoid membrane of the brown alga (Undaria pinnatifida Harv.) by using non-ionic detergent decanoyl-N-methylglucamide and PAGE technique. According to the apparent molecular weights, spectra characteristics, polypeptide compositions and referring to the higher plant spinach, eight pigment-protein complexes were named under Anderson's terminology system as CP I a, CP I, CPa, LHC1, LHC2, LHC3, LHC4, LHC5.

Screening of salt tolerant watercress variants on natural seawater contained medium

The responses of stem segments of watercress (Nasturtium officinale R. Br.) to 6-BA,NAA and 2,4-D were studied. MS medium supplemented with 2.0 mg/L 6-BA, 0.2 mg/L 2,4-D was used for callus initiation and maintenance. MS medium supplemented with 4.0 mg/L 6-BA was suitable for plant regeneration and MS medium without plant hormone supplement was used for rooting and plant propagation. For screening of salt tolerant calli, stem segments of watercress were plated onto callus initiation medium containing 1/3 natural seawater. Seventeen out of the 325 plated explants produced calli. The growth curves demonstrated that the growth rate of salt-tolerant calli on saline medium almost matched that of the control calli on normal medium. Some of the salt-tolerant calli were transferred to the normal regeneration medium or saline regeneration medium to induce plant regeneration. In the first case, buds and shoots were regenerated in the same way as those of control calli on normal regeneration medium. More than 1 000 regenerated shoots were obtained of which 83 regenerated shoots were cut and transferred to saline MS base medium. At first, all shoot growth was inhibited, but 40 days after the transfer, rapid-growing axillary shoots were observed on 16 of the original shoots but none on the control shoots on saline MS base medium. Moreover, green spots appeared on most calli 10 days after they were transferred to saline medium, however buds appeared only on 5 calli from the 30 transferred calli and at the end only 2 rapid-growing shoots were obtained from two calli. In total, 18 variant lines were obtained through. propagation of the salt-tolerant shoots on saline MS base medium. RAPD analysis was performed in 10 of the 18 salt-tolerant variant lines and DNA variation was detected in all the tested variant lines.

Antifeedant, antibacterial, and antilarval compounds from the South China Sea seagrass Enhalus acoroides

We investigated chemical constituents and the antifeedant, antibacterial, and antilarval activities of EtOH (ethanol) extracts of the South China Sea seagrass Enhalus acoroides. Eleven pure compounds including four flavonoids and five steroids were obtained. Among these compounds, three flavonoids were antifeedant against second-instar larvae of Spodoptera litura, two flavonoids had antibacterial activity towards several marine bacteria, and one flavonoid showed strong antilarval activity against Bugula neritina larvae. This is the first description of isolation and bioactivity of secondary metabolites from E. acoroides.

Dynamics of dimethylsulfide and dimethylsulfoniopropionate produced by phytoplankton in the Chinese seas - Distribution patterns and affecting factors

Distribution of dimethylsulfide (DMS) and/or particulate dimethylsulfoniopropionate (DMSPp) concentrations in the Jiaozhou Bay, Zhifu Bay and East China Sea were investigated during the period of 1994 - 1998. Both DMS and DMSPp levels showed remarkable temporal and spatial variations. High values occurred in the coastal or shelf waters and low values in the offshore waters. The highest levels were observed in spring or summer and lowest in autumn. DMS or DMSPp distribution patterns were associated with water mass on a large geographical scale, while biological and chemical factors were more likely influential on smaller-scale variations. Diatoms could play an important role in total DMS or DMSPp abundance in coastal waters. Nitrate was found to have a two-phase relationship with DMSPp concentrations: positive when nitrate concentration was lower than 1 mumol/L, and negative when it was above. Anthropogenic factors such as sewage input and aquaculture also showed influences on DMS or DMSPp concentration.

A New Triterpenoid from Amoora dasyclada

Five compounds were isolated from the EtOH extraction of the stem of Amoora dasyclada (How et T. Chen) C. Y. Wu (Meliaceae). On the basis of spectroscopic methods, their structures were elucidated as 24, 25-epoxy-tirucall-7-ene-3, 23-dione (1), 24, 25, 26, 27-tetranortirucall-7-ene-3-oxo-23(21)-lactone (2), taraxerone (3), taraxerol (4) and b-sitosterol (5). Among them, compound 1 was a new triterpenoid, compounds 3-5 were firstly obtained from this plant; compound 2, an tetranortriterpenoid, was firstly isolated from natural sources, and its NMR data were assigned for the first time. Moreover, the D7-bond and the Me-14 in compound 2 were never changed, which has never been found in other tetranortriterpenoids. And the biosynthetic pathway of tetranortriterpenoid was further discussed.

A Simulative Study on Effects of Climate Warming on Nutrient Contents and In Vitro Digestibility of Herbage Grown in Qinghai-Xizang Plateau

The increasing trend of air temperature along with the climate warming has been accepted gradual-ly by scientists and by the general public. Qinghai-Xizang Plateau, a unique geographic unit due to high-altitude climate, is one of the most susceptible regions to climate warming. Its ecosystem is very fragile and sensi-tive to climate change. In order to get a better understanding of the impacts of climate warming on the nutrient contents of herbage grown in Qinghai-Xizang Plateau, a simulative study was implemented at Daban Moutain by using temperature differences resulted from sites selected at different altitudes and nutrient contents and in vitro digestibility were determined for assessing the quality of the grown herbage. There were significant downtrends in crude protein (CP), ether extract (EE) and nitrogen free extract (NFE) contents of herbage along with the increase of temperature. It had a positive correlation between temperature and content of acid detergent fibre (ADF), acid detergent lignin (ADL) in herbage. In vitro digestibility of herbage decreased along with the in-crease of temperature. The results of this study indicated that climate warming significantly influence nutrient contents and in vitro digestibility of herbage grown in Qinghai-Xizang Plateau. It is suggested that the future climate warming especially the gradual rise of the night temperature could cause negative effect on herbage quality grown in Qinghai-Xizang Plateau by decreasing CP, EE, and NFE contents and increasing some indi-gestible ingredients such as crude fibre (CF), neutral detergent fibre (NDF), ADF, and ADL. This, conse-quently, decreases the ruminant assimilation ability.

Floral Organogenesis and Development of two Taxa in Tribe Hyoscyameae (Solanaceae)-Przewalskia tanguitca and Hyoscyamus niger

Floral organogenesis and development of Przeivalskia langutica Maxim, endemic to China and Hyoscyamus niger L. , which belong to the tribe Hyoscyameae (Solanaceae), were studied using scanning electron microscope. They have three common characters of floral organ initiation and development: 1) initia-tion of the floral organs in the two species follows Hofmeister's rule; 2) the mode of corolla tube development belongs to the "late sympetaly" type; 3) primordia of the floral appendages initiated in a pentameroua pattern and acropetal order. But initiation of the calyx-lobe primordia showed different modes in these two species. The calyx-lobe primordia of H, niger have simultaneously whorled initiation, while those of P, tangulica have helical initiation, but the five calyx-lobe primordia form a ring after all five calyx-lobe primordia occur. The systematic significance of the present results in the genera Hyoscyamus and Przeivalskia is discussed in this paper.

No C_4 Plants Found at the Haibei Alpine Meadow Ecosystem Research Station in Qinghai, China: Evidence from Stable Carbon Isotope Studies

Using the measurement of stable carbon isotopes in leaves as a tool to investigate photosyn-thetic pathway of 102 plant species grown at an alpine meadow ecosystem, at the foot of the Qilian Mountain, Qinghai, China. The results indicate that the δ~(3)C values of plants have a narrow range from -28.24‰ to -24.84‰, which means that none of the species examined belongs to C_4 and crassulaceous acid metabolism (CAM) photosynthetic pathway and all of these species perform photosynthesis through the C_3 pathway. This is likely due to a long-term adaptation to environments at the alpine meadow ecosystem.

Cytological and Molecular Identification of Alien Chromatin in Giant Spike Wheat Germplasm

Alien chromosomes of twelve giant spike wheat germplasm lines were identified by C-banding, genomic in situ hybridization (GISH), sequence characterized amplified region (SCAR), and random amplified polymorphic DNA (RAPD). All lines showed a chromosome number of 2n = 42, five of them carried both a pair of wheat-rye (Triticum aestivum-Secale cereal) 1BL/1RS translocation chromosomes and a pair of Agropyron intermedium (Ai) chromosomes, three carried a pair of Ai chromosomes only, three others carried a pair of 1BL/1RS chromosomes only, and one carried neither 1BL/1BS nor Ai chromosome. Further identification revealed that the identical Ai chromosome in these germplasm lines substituted the chromosome 2D of common wheat (Triticum aestivum L.), designated as 2Ai. The genetic implication and further utilization of 2Ai in wheat improvement were also discussed.