The full-length cDNA of the g subunit of R-phycoerythrin from Corallina officinalis L. was cloned by rapid amplification of cDNA ends (RACE) method, and sequenced. The full-length cDNA is a 2 308 bp consisting of 5'' untranslated region (UTR) of 1 203 bp, an open reading frame (ORF) of 960 bp that encodes 320 amino acids, and 3'' UTR of 145 bp. The mature g polypeptide contains two unique internal repeat domains as reported by Apt et al. (2001). Sequence analysis of the different clones revealed different 3''-end sequences at the g subunit. The difference between the 3''-end sequences suggests that the g subunit may have more than one copy, or have gone through different post-transcriptional modification. By comparing the DNA and cDNA sequences, we found that the g subunit is an intronless gene. This is the first report of the g subunit gene of R-phycoerythrin from C. officinalis .
The fossil Pediastrum was investigated from the Gaoximage section ( 42 57''14'''' N, 115 22''3'''' E, Alt 1 253 m ) in the Hunshandak Sandy Land, Inner Mongolia (Nei Mongol) of China in order to gain a better understanding the changes of palaeovegetation, palaeoenvironment and palaeoclimite since 5 000 aBP when the pollen-spore was studied. The results show that the fossil Pediastrum assemblage can be divided into three periods: Ⅰ. 5 000-3 500 a BP, the fossil Pediastrum occurred rarely. Based on this result it can be surmised that the lake might be fresh water with poor organics.Ⅱ. 3 500-1 500 a BP, the fossil Pediastrum likes volcanic emerged. It probably indicate moist conditions and the grasslands were developed during this time; and Ⅲ. 1 500-200 a BP, the fossil Pediastrum disappeared. It can show that the lake water become salty and shrunk, and the weather could become drier and drier. This result shows that Pediastrum, a kind of facies fossil, happened simultaneously in the pollen-spore assemblage during the second period. Sometimes Pediastrum can reach more than 60 per cent of the total spore pollen assemblage, indicating that Gaoximage lake was not only fresh water with abundant eutrophic materials but also occu-pied a large area during 3 500-1 500 a BP.
In the atmosphere of Edirne 12 691 pollen grains belonging to 42 taxa were identified by using of Durham sampler in 2000 and 2001. A total of 6 189 pollen grains per cm² were recorded in 2000 and a total of 6 502 pollen grains per cm² in 2001. Total pollen grains consisted of 71.81% grains from arboreal plants, 25.88% grains from non-arboreal plants and 2.31% unidentified pollen grains. Pollen from the following taxa were also found to be prevalent in the atmosphere of Edirne: Gramineae, Pinus sp., Quercus sp., Cupressaceae/Taxaceae, Platanus sp., Salix sp., Morus sp., Populus sp., Carpinus sp., Juglans sp., Chenopodiaceae/Amaranthaceae, Fraxinus sp., Fagus sp., Ulmus sp., Ailanthus sp., Alnus sp., Ostrya sp., Helianthus sp. The season of maximum pollen fall was from April to June, with a prevalence of arboreal pollen in the first month, and of pollen from non-arboreal plants in the last months of the year.
Using field experimental data of 17 yr of mowing succession of Leymus chinensis (Trin.) Tzvel. steppe of Inner Mongolia (Nei Mongol), we analyzed the dynamics of community composition based on plant functional groups (PFGs), explored the relationship between changes of the PFGs proportion in community and the community annual net primary production (ANPP), and examined the influences of structural parameters on functional parameters. Our results showed that during 17 yr of mowing succession, changes in both community structure and function took place. The roles of different PFGs varied appar-ently with mowing succession: the dominance of rhizome grasses was replaced successively by annuals and biennials, tall bunch grasses, and short bunch grasses. Following 17 yr of mowing, the community became co-dominated by rhizome grasses, tall bunch grass, and short bunch grass. ANPP correlated significantly with annual precipitation in control plot, but not in successive mowing plot. Annual precipita-tion explained more than 62% of the annual variability in ANPP of control plot, whereas annual variation of ANPP in mowing plot was mainly driven by successive mowing disturbance. The community ANPP showed resilience to mowing disturbance and kept relatively stable initially through internal regulation of PFGs, and declined to a lower level with structural changes of the community after about 5 yr, and then again maintained at a stable level through structural regulation. Therefore, in mowing succession the commu-nity structure represented by PFGs changed gradually while the community function represented by ANPP declined abruptly. The community relied on constantly regulating the structure to maintain the function stability. The community function would degrade after its structure changed to certain degree.
Primula interjacens Chen (Primulaceae) is a rare and narrow endemic species of central-south of Yunnan Province in China. This species consists of two varieties: P. interjacens var. interjacens known with only one population, and P. interjacens var. epilosa with two populations. Inter-simple sequence repeat (ISSR) marker was used to detect the genetic diversity of the three extant populations. We expected a low genetic diversity level, but our results revealed a high level of intraspecific genetic diversity (at population level: P = 59.75%, HE = 0.236 8, and Hpop = 0.345 9; at species level: P =75.47%, HT = 0.320 5, and Hsp = 0.461 8), probably resulting from floral heteromorphism and preferring outcrossing. A moderate level of genetic differentiation among populations was detected based on Nei’s genetic diversity analysis (26.13%) and Shannon’s diversity index (25.09%). Although P. interjacens var. interjacens and P. interjacens var. epilosa were morphologically distinct, UPGMA cluster analysis showed that the two varieties had no distinct genetic differentiation and may be treated as a single taxon. Conservation measures are suggested, including in situ and ex situ strategies, based on the observed population genetic information.
To assess the ecophysiological responses and adaptive strategies to rainfall exhibited by different plant functional types, we compared gas exchange, leaf water potential (Yleaf) and PSⅡ photochemical efficiency (Fv/Fm) between Hedysarum fruticosum Pall. (shrub) and Salsola collina Y. L. Chang (herb) under a series of simulated rainfalls. The experiment was conducted in Hunshandak Sandy Land, North China. The values of net photosynthetic rate (Pn), transpiration rate (E), stomatal conductance (gs), Fv/Fm and Yleaf always elevated with the increasing amount of simulated rainfall. Whereas water use efficiency (WUE) maintained constant in H. fruticosum while always decreased in S. collina. Both species fully recovered their Pn and Fv/Fm 3 d after rainfall, while gs and Yleaf recovered only within 2 d. However, the response patterns were obviously different. H. fruticosu promote its physiological traits within 5-15 mm rainfall but no further positive enhancement was noted when rainfall was larger than 15 mm. In S. collina, however, the enhancement continued with more water applied. We inferred that H. fruticosum and S. collina responded similarly to rainfall in time courses but differential to simulated precipitation change. S. collina was likely to be physiologically sensitive to instant increasing soil water, that can be regarded as a prodigal water use type; whilst H. fruticosum was a conservative water user.
The economic seaweed Hizikia fusiforme (Harv.) Okamura (Sargassaceae, Phaeophyta) usually experiences periodical exposures to air at low tide. Photosynthetic carbon acquisition mechanisms were comparatively studied under submersed and emersed conditions in order to establish a general understanding of its photosynthetic characteristics associated with tidal cycles. When submersed in seawater, H. fusiforme was capable of acquiring HCO3- as a source of inorganic carbon (Ci) to drive photosynthesis, while emersed and exposed to air, it used atmospheric CO2 for photosynthesis. The pH changes surrounding the H. fusiforme fronds had less influence on the photosynthetic rates under emersed condition than under submersed condition. When the pH was as high as 10.0, emersed H. fusiforme could photosynthesize efficiently, but the submersed alga exhibited very poor photosynthesis. Extracellular carbonic anhydrase (CA) played an important role in the photosynthetic acquisitions of exogenous Ci in water as well as in air. Both the concentrations of dissolved inorganic carbon in general seawater and CO2 in air were demonstrated to limit the photosynthesis of H. fusiforme, which was sensitive to O2. It appeared that the exogenous carbon acquisition system, being dependent of external CA activity, operates in a way not enough to raise intracellular CO2 level to prevent photorespiration. The inability of H. fusiforme to achieve its maximum photosynthetic rate at the current ambient Ci levels under both submersed and emersed conditions suggested that the yield of aquaculture for this economic species would respond profitably to future increases in CO2 concentration in the sea and air.
Cytoplasmic membrane of Nostoc flagelliforme Born. et Flah. was isolated for the first time with a new method, the unique feature of which is the combined use of French pressure cell and digitonin to disrupt cells. After passed twice through French pressure cell (at 80 MPa), cells in sample (20 mg of dry weight/mL) were disrupted effectively by digitonin (3 mg/mL), and then the cytoplasmic membrane was isolated by density gradient centrifugation. The membrane contained carotenoids with absorption peaks at 458, 487 and 524 nm and a precursor of chlorophyll a with a minor peak at 673 nm. The fluorescence emission peaks of the membrane were emitted from the precursor of chlorophyll a. More than 30 polypeptides were detected in the membrane, in which the most obvious corresponded to the polypeptides with molecular mass of 80, 28, 19 and 17 kD. The membrane contained four types of glycerolipids: MGDG (62.4%), DGDG (18.9%), SQDG (16.7%) and PG (2.0%). 16:0, 16:1 , 18:0, 18:1 , 18:2 [9, 12] and 18:3 [9, 12, 15] fatty acids were determined in the membrane, in which 16:1 and 18:3 fatty acids were the main components, representing 32.3% and 34.4% of the total fatty acids respectively. High proportion of 18:3 fatty acid in the cytoplasmic membrane may be an important factor of N. flagelliforme in its remarkable drought-tolerant ability.
The main light-harvesting chlorophyll a/b -protein complex (LHCⅡ) has been isolated directly from thylakoid membranes of shiphonous green alga, Bryopsis corticulans Setch. by using two consecutive runs of anion exchange and gel-filtration chromatography. Monomeric and trimeric subcomplexes of LHCⅡ were obtained by using sucrose gradient ultracentrifugation. Pigment analysis by reversed-phase high performance liquid chromatography showed that chlorophyll a (Chl a), chlorophyll b (Chl b), neoxanthin, violaxanthin and siphonaxanthin were involved in LHCⅡ from B. corticulans. The properties of electronic transition of monomeric LHCⅡ showed similarities to those of trimeric LHCⅡ. Circular dichroism spectroscopy showed that strong intramolecular interaction of excitonic dipoles between Chl a and between Chl b exist in one LHCⅡ apoprotein, while the intermolecular interaction of these dipoles can be intensified in the trimeric structure. The monomer has high efficient energy transfer from Chl b and siphonaxanthin to Chl a similarly to that of the trimer. Our results suggest that in B. corticulans, LHCⅡ monomer has high ordered pigment organization that play effective physiological function as the trimer, and thus it might be also a functional organization existing in thylakoid membrane of B. corticulans.
Alpha-picolinic acid (PA) is an apoptosis inducer in animal cells, and could elicit hypersensitive response (HR) in rice, a monocotyledonous model plant. Here we report that PA is an HR inducer in plants. It induced HR in Arabidopsis, a dicotyledonous model plant, including the oxidative burst and cell death. We investigated defense signal transduction activated by PA through marker genes of particular defense pathways in Arabidopsis. The result indicated that both the salicylic acid-dependent and jasmonic acid/ethylene-dependent pathways were activated by PA, in which the marker defense genes PR -1, PR -2 and PDF1.2 were all induced in dose-dependent and time-course manners. We also observed that the PA-induced reactive oxygen species (ROS) production in rice suspension cells was Ca2+-dependent. Together with our previous studies of PA-induced defense activation in rice, we conclude that PA acts as a non-specific elicitor in plant defense and has a potential utilization in cellular model establishment of systemic acquired resistance (SAR) activation.
In the present research, flow cytometry (FCM), simple sequence repeat (SSR) and cleaved amplified polymorphic sequence (CAPS) were employed to analyze somatic hybrid plants derived from electrofusion between embryogenic protoplasts of sweet orange (Citrus sinensis Osbeck cv. Shamouti) and leaf-derived protoplasts of sour orange (C. aurantium L.). FCM showed that all of the somatic hybrid plants had two-fold fluorescence intensity values of the diploid control, indicating that they were tetraploids. SSR and CAPS were used to characterize the compositions of nuclear and cytoplasmic genomes of the somatic hybrid plants. As for SSR four primer pairs were tried and two showed polymorphisms between the fusion parents. With both primer pairs the somatic hybrid plants encompassed DNA bands from both parents, indicating that they were heterokaryonic hybrids. Amplification with some universal primers, followed by digestion with restriction endonucleases, could distinguish the fusion parents from each other. As far as mitochondrial and chloroplast DNA compositions were concerned the somatic hybrid plants shared the same banding patterns as the embryogenic parents for all of the polymorphic primer/enzyme combinations. The results herein demonstrated that the somatic hybrid plants inherited their nuclear genome from both fusion parents, whereas the cytoplasmic genomes were possibly only contributed by the embryogenic parent. Merits of the analytical methods and nuclear and cytoplasmic inheritance of citrus tetraploid somatic hybrids, together with their application, are discussed herein.
Heat shock cognate proteins 70 (hsp70s) act as molecular chaperones. Some hsp70s are also expressed in unstressed plants, known as hsc70. To gain further knowledge about the hsc70, the Thellungiella halophila hsc70 (Thhsc70) gene that encoded the cytosolic hsc70 in salt cress (T. halophila (C. A. Mey.) O. E. Schulz) was identified. In unstressed plants the expression of Thhsc70 was shown to be tissue-specific. The Thhsc70 gene was induced by heat and cold stresses, but almost not by salt and drought stresses. Overexpression of Thhsc70 could increase thermotolerance and chilling tolerance in transgenic Arabidopsis plants.
Rice (Oryza sativa L.) glutelin accounts for about 80% of total seed storage protein. Glutelin can be easily digested by human and contains high concentrations of lysine and other essential amino acids. To improve the nutritional quality of wheat (Triticum aestivum L.), the cDNA sequence of rice glutelin gene GluA-2 was introduced into common wheat through biolistic bombardment. Six hundreds of immature embryos from wheat cultivar Bobwhite (T. aestivum cv. Bobwhite) were bombarded. Four transgenic plants carrying GluA-2 gene were confirmed by PCR and Southern blotting analyses. Gene GluA-2 was translated in three of the transgenic plants and their progeny, as indicated by SDS-PAGE analyses. The expression of GluA-2 gene was not detected in one transgenic plant and the endogenous wheat high molecular weight glutenin subunits Bx7 and By9 contents decreased greatly in both T0 and T1 generations.
An enolase-encoding cDNA clone in oilseed rape (Brassica napus L.) was isolated. This gene (accession number: AY307449) had a total length of 1 624 bp with an open reading frame of 1 335 bp, and encoded a predicted polypeptide of 444 amino acids with a molecular weight of 47.38 kD. The deduced amino acid sequence shared identity with a number of enolases ranging from Bacillus subtilis to human beings and had much higher identity with other plant enolases than with enolases from Bacillus, yeast and human beings. Comparison of its primary structure with those of other enolases revealed the presence of an insertion of five amino acids in enolase of B. napus. Southern blotting analysis of genomic DNA indicated that enolase was likely to be a low-copy gene in the oilseed rape genome. Expression of the cloned enolase gene increased under salt stress, but decreased in response to low temperature. Our studies suggested that the cloned gene was a new member of plant enolase gene family, which contributed to the energy supply in stress-treated tissues.
Fluorescent in situ hybridization (FISH) was used to investigate the chromosomal location of 18S-5.8S-26S rDNA loci in Thinopyrum intermedium (Host) Barkworth et Dewey (2n=6x=42). In all accessions and individuals studied, 3 or 4 pairs of major loci were detected. Subsequent genomic in situ hybridization (GISH) analyses revealed that one pair was located on the ends of the short arms of one pair of homologous chromosomes of the St genome, while the other 2 or 3 pairs of major loci were located in the E genomes (including the Ee and Eb). It is suggested that 2 to 3 pairs of major loci were probably lost during the evolution of this hexaploid species. The variation in rDNA positions and copy numbers between the diploid donors and Th. intermedium, as well as the diversity among the accessions of Th. intermedium confirmed that the rDNA gene family conveyed the characters of DNA mobile elements. The internal transcribed spacer (ITS) regions of the rDNA in Th. intermedium were also investigated. Sequence data of seven positive clones from one individual suggested high degree of individual heterogeneity exists among ITS repeats. Phylogenetic analyses showed that there were two distinct types of ITS sequences in Th. intermedium, one with homology to that of Pseudoroegneria species (St genome) and the other to that of the E genome diploid species. This showed that the ITS paralogues in Th. intermedium have not been uniformly homogenized by concerted evolution. The limitation of using the chromosomal location of rDNA loci for phylogenetic analysis is discussed.
Camptotheca acuminata Decne. (Nyssaceae) is a major source of the anticancer camptothecin (CPT). It is important to understand how CPT accumulates in C. acuminata in order to improve CPT production strategies. The aim of this study was to anatomically and morphologically characterize the secretory structure in leaves and stems of C. acuminata and determine their relationship to accumulation of CPT. Secretory canals and glandular trichomes were found in young stems and young leaves. Secretory canals consisted of a sub-epidermal canal delimited by one to two layers of cells. Glandular trichomes were unicellular. Fluorescence microscopy and CPT analysis showed that CPT was primarily accumulated in secretory canals and glandular trichomes of leaves and stems.
The moisture loss degree is important in determining the quality of post-harvest mushroom (Agaricus bisporus (Lange) Sing). Quantitative roughness analyzed by atomic force microscopy (AFM) was proposed to denote the degree of shrinkage, with arithmetic average roughness (Ra) and root mean square roughness (Rq) as parameters. The initial value of Ra was (30.035±1.839) nm, while those of 2 ℃, 25 ℃ and dynamic temperature on the 2nd day were (40.139±3.359) nm, (54.393±13.534) nm and (41.197± 6.555) nm, respectively. There is a similar tendency for the results of Ra and Rq. Both values of roughness increased in duration of storage and with increasing temperatures. The three-dimensional profile of the pileus epicutis could signify the process of water evaporation intuitionally. The tendency was in accordance with the roughness results, especially for the earlier stage of the storage (0-2 d). The outcome of roughness analysis could signify the differences of storage conditions. It was shown that the roughness measured by atomic force microscopy effectively reflected the moisture loss degree of the mushroom pileus epicutis during post-harvest storage.
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.
For Upcoming Special lssue: