Atomic force microscopic observation on substructure of pollen exine in Cedrus deodara and Metasequoia glyptostroboides

The substructure of pollen exine in Cedrus deodara (Roxb.) Loud. and Metasequoia glyptostroboides Hu et Cheng has been examined with an atomic force microscope (AFM). The results indicate that the exine substructure units containing sporopollenin in two species are similar in shape, which are granular, but slightly different in size. In Cedrus the substructure unit of pollen exine appears to be 56-99 nm long and 42-74 nm wide, while in Metasequoia it appears to be 81-118 nm long and 43-98 nm wide. It has been observed that the subunits of pollen exine in Cedrus arranged tightly to form short-rod-like or spheroidal pollen exine units, several or more than ten of which formed an island-like structure. There are various spaces among these island-like structures which are interconnected to occupy the entire pollen exine. In Metasequoia, the subunits of pollen exine also arranged tightly with a distribution tendency of cluster of 3-10, however, no obvious boundary exists among these clusters. From our results, it is concluded that there is no tendency of helical arrangement for the subunits of pollen exine in Cedrus and Metasequoia, and the results support Southworth' view that subunits of pollen exine are granular shape in lattice structure.     

Preparation of exine-detached pollen inNicotiana tabacum

A method of preparing exine-detached pollen inNicotiana tabacum was established. Anthers containing early-middle binucleate pollen were cold-pretreated at 4–6°C for 7–14 days, and were suspended in 0.3 mol/L sucrose solution for 2 days. During this process, the exine of most pollen grains dehisced. Then they were transferred into an enzyme solution containing 1% cellulase, 1% pectinase, 0.1% pectolyase, 1 mol/L mannitol, 0.3 mol/L sorbitol, 0.5% potassium dextran sulphate and K3 medium macro elements. After 15–20 min enzymatic maceration, the exine was detached resulting in the release of exine-detached pollen. Factors affecting preparation of exine-detached pollen were investigated, including cold-pretreatment, osmoticum concentration and enzymes used. Xia Huijun: born in Oct. 1963, Ph.D. Current research interest is in plant reproductive biology Supported by the National Natural Science Foundation of China     

Pollen Morphology of Artemisia L. and Its Systematic Significance

The pollen of 57 species representing 7 sections of Artemisia was examined hy light microscope and scanning microscope for the purpose to elucidate the systematic relationships of the genus. The examination indicates that the pollen grains present high concordance which is characterized by the globular or the appruximate shape. 3-lobed circular from polar view while granular or ellipse sphere from tropical plate with tricolporate structure. The exinc of pollen has an obvious double structure of inner and outer layers (including the tecturn and columnar layers) where the outer is thicker than the inner and the sculpture of exine degenerates into small spinules easily distinguishable from other genera of the Compositae. Based on cxine sculpture, the pollen grains of Artemisia can be divided into two types: Myriantha type and Mongolica type, which possesses 4 subtypes according to the distribution forms of spinulc: (1) Sacrorum subtype, (2) Oligocarpa subtype, (3) Lavandulaefolia subtype. (4) Anomale subtype.     

蜘蛛抱蛋属花粉扫描电镜研究

为进一步研究蜘蛛抱蛋属植物的起源,演化及自然分类,用扫描电子显微镜观察蜘蛛抱蛋属（Aspidistra)的棒芯蜘蛛抱蛋（A.claviformis),丛生蜘蛛抱蛋（A.caespitosa)、峨边蜘蛛抱蛋（A.ebianensis)、辐花蜘蛛抱蛋(A.subrotata)、棕叶草（A.oblanceifolia)、广东蜘蛛抱蛋（A.lurida)、乐山蜘蛛抱蛋（A.leshanensis)、海南蜘蛛抱蛋（A.hainanensis)、大花蜘蛛抱蛋（A.tonkinensis)、罗甸蜘蛛抱蛋（A.luodianensis)的花粉形态,每种植物采发育正常含包待放的花1－3朵,取花粉用艾特曼醋酸法处理后,CO2临界点干燥,导电胶贴于样台,真空喷金镀膜,置于扫描电子显微镜下观察、测量及照相。详细地描述各种花粉的外部形态。10种蜘蛛抱蛋属植物花粉均为近球形或球形,无萌发孔,外壁纹饰可分为：皱波状纹饰和小芽孢状纹饰。不同种植物花粉外壁纹饰存在一定差异,二类型花粉外壁纹存在一定的演化关系。     

Magnetic properties and giant magnetoresistance effect of nanometer Fe−In2O3 granular films

Nanometer ferromagnetic metal-semiconductor matrix Fe−In₂O₃ granular films are fabricated by the radio frequency sputtering. Magnetic properties and the giant magnetoresistance (GMR) effect of Fe_x(In₂O₃)_1−x granular film samples are studied. The result shows that the magnetoresistance (MR) ratio Δρ/ρ ₀ value of the granular film samples with Fe volume fraction x=35% is 4.5% at room temperature. The temperature dependence (T=1.5–300 K) of the MR ratio Δρ/ρ ₀ value of Fe_0.35(In₂O₃)_0.65 granular films shows that Δρ/ρ ₀ value below 10 K increases rapidly with the decrease of the temperature, and when T=2 K, Δρ/ρ ₀ value is 85%. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that, when the temperature decreases to a critical point T _p=10 K, the change of the structure in Fe_0.35)In₂O₃)_0.65 granular films results in the transformation of state from ferromagnetic to spin-glass-like. The remarkable increase of the MR ratio Δρ/ρ ₀ value of Fe_0.35(In₂O₃)_0.65 granular films below 10 K seems to arise from the peculiar conducting mechanism of the granular film samples in the spin-glass-like state.     

Relationship between stomatal density and the changes of atmospheric CO2 concentrations

The relationship between the stomatal density of five woody plants endemic to China, i. e.Eucommia ulmoides, Quercus liaotungensis, Q. glandulifera var.brevipetiolata, Cyclocarya paliurus andFicus heteromorpha, and the atmospheric CO₂ concentrations was studied by observations on leaves of the herbarium-stored specimms(1920s–1990s). The results showed that the stomatal density inEucommia ulmoides, Quercus liaotungensis andQ. glandulifera var.brevipetiolata decreased significantly in response to the elevated atmospheric CO₂ concentrations, while inCyclocarya paliurus it decreased slightly and inFicus heteromorpha there were no responses.     

The concentration quenching characteristics of 5D3-7FJ and 5D4-7FJ (J=0―6) transitions of Tb3+ in YBO3:Tb3+ phosphor

The photoluminescence quenching behaviors of ^5D3-^7Fj and ^5D4-^7Fj （J = 0—6） transitions of Tb^3＋ in YBO3：Tb under 130—290 nm excitation were systematically investigated. The results revealed that the quenching concentrations of both ^5D3-^7Fj and ^5D4-^7Fj transitions of Tb^3＋ in YBO3：Tb were mainly dependent on excitation wavelength. Particularly, the quenching concentrations of ^5D4-^7Fj transitions of Tb^3＋ under 130—290 nm excitation were correlated with excitation bands of YBO3：Tb. The quenching concentrations of ^5D3-^7Fj transitions remained at low concentration （2%） under 186—290 nm excitation and then increased gradually with energy of incoming excitation photon when excited at 130—186 nm. This dependence should be involved in their excitation mechanisms and quenching pathway in particular excitation region.[第一段]     

Superconvergence for L2-projection in finite elements

Two classes of superconvergence points for L 2 projection u\-n in n degree finite elements on uniform grids are shown by element analysis method. Superconvergence points of u n are n+1 order Gauss point G n+1 for odd d≥1 (so the endpoint of each element is of superconvergent), and n+1 order pointset Z n+1 for even n ≥2 (which includes the endpoints and midpoint), respectively. Symmetry point is only an important part of them.     

Characterization of the flagellar biosynthesis regulatory geneflbD inAzospirillum brasilense

A flagellar gene cluster fragment includingflbD ofAzospirillum brasilense was cloned and sequenced. TheflbD mutant strain was found to be nonmotile—losing both polar and lateral flagella (Fla⁻Laf⁻). Motility and flagella were regained by complementation with plasmid-borne multicopyflbD, but altered with larger swarming circle and fewer lateral flagella on the semisolid plate. This result indicated that FlbD plays an important role in the regulation of both polar and lateral flagellar biosynthesis inA. brasilense.     

Experimental proof for the regulation ofSalmonella typhimurium purB bypurR

Salmonella typhimurium purB encodes adenylosuccinate lyase (ASL), the enzyme that catalyzes step 8 in the pathway forde novo synthesis of inosine 5′-monophosphate (IMP) and also the final reaction in the two-step sequence from IMP to adenosine monophosphate (AMP). The nucleotide sequence ofpurB was obtained by the genetic map and sequence homologous analysis. The conservedpur operator inpurB was identified to be located 185 bp downstream of the initiation codon and overlaps codons 62 – 67 in the protein-coding region. The binding of PurR to this operator was demonstrated by gel retardation experiment and site-directed mutagenesis, indicating that thepurB is under the control ofpurR. We also answered why previous study had conflicting report concerning the regulation ofpurB bypurR by identifying the junction site ofpurB tolacZ in apurB- MudJ (lacZ,Kan ^r) fusion strain. This result strongly supports that thepurB is the second gene in theycfC-purB operon.     

Preparation and optical properties of solid solution semiconductor (Zn x Cd1−x S) doped silica glasses

Semiconductor(Zn_xCd_1−x S) doped silica glasses were prepared by Sol-Gel process andin situ growth technique. The structure of the materials was characterized by X-ray diffraction technique, the particle size of semiconductor crystallites from X-ray patterns was estimated less than 10 nm. From absorption spectra, it is obtained that the absorption edges shifted to short wavelength direction when Zn contents increased, and the absorption edge can be adjusted from 2.46 eV to 2.96 eV by controlling Zn contents. The third-order nonlinear optical susceptibility was studied at 532 nm with 8 ns pulse laser by degenerate four wave mixing (DFWM) technique.     

Cryopreservation of pollen by vitrification inBrassica

The key factors affecting pollen cryopreservation by vitrification inBrassica campestris var.purpurea were investigated. The factors involved the pollen maturity, the pollen resistance to dehydration, the components of vitrification solution (PVS), and the concentration of diluent. Thus, a suitable procedure was established for pollen vitrification, the maximum relative survival rates of mature (at the day of anthesis) and nearly mature (3 days before anthesis) pollen were about 80%, 63% respectively. This procedure has been also successfully applied to two other species (Brassica napus, Brassica chinensis). The advantage of cryopreservation of pollen by vitrification was discussed. Xu Bingfang: born in Sep. 6. 1970, Ph. D graduate student     

Root and xylem ABA changes in response to soil drying in two woody plants

Two woody plants, Platycladus orientalise (tolerant to drought) and Acacia auriculi-formis (sensitive to drought), have been subjected to rapid and slow soil drying. ABA levels in their roots and xylem sap have been determined using radioimmunoassay (RIA, sensitivity is 0.4 pmol per assay vial) with a monoclonal antibody against ( + )-ABA. ABA contents of P. orientalise and A. auriculiformis growing in well watered soil are 0.3 and 2.5 nmol·gDW-1 in roots and 1.6 and 0.4 μmol in xylem saps, respectively. A rapid soil drying has been applied to these two plants with soil water content (SWC) being reduced to 0.02 and 0.06 g·gDW-1 respectively. Under such treatment, ABA was increased by 22 times and 2 times in roots and by 7 times and 34 times in xylem saps respectively for P. orientalise and A. auriculiformis. After rewatering for 6 d, ABA in roots and xylem sap of both species returned to control levels. When a slow soil drying was applied, SWC was reduced to 0.1 and 0.13 g·gDW-1 respectively for P. orientalise and A. auriculiformis. ABA was increased by 5 times and 1.6 times in roots and by 6 times and 19 times in xylem saps respectively for these two plants. ABA in roots and xylem saps decreased to near control levels 8 d after watering. Plant leaf water potentials of both plants hardly changed at times when root and xylem ABA showed substantial increase in response to soil drying. It is concluded that ABA levels in the roots and xylem saps of P. orientalise and A. auriculiformis are more sensitively regulated than leaf water potential in response to soil drying and can act as a chemical signal in root-shoot communications of the drought stress.     

Characterization of type<Emphasis Type="Italic">p</Emphasis> Banach spaces by the weak law of large numbers

For weighted sums of the form where {a _nj , 1 ⩽j⩽k _n ↑∞,n⩾1} is a real constant array and {X _aj , 1≤j≤k _{n, n}≥1} is a rowwise independent, zero mean, random element array in a real separable Banach space of typep, we establishL ^r convergence theorem and a general weak law of large numbers respectively, conversely, we characterize Banach spaces of typep in terms of convergence inr-th mean and probability for such weighted sums. Foundation item: Supported by the National Natural Science Foundation of China (No. 10071058) Biography: Gan Shi-xin (1939-), male, Professor, research direction: martingale theory, probability limiting theory and Banach space geometry theory.     

Secular variations in geomagnetic Field caused by the fluctuations in the fluid flow in the outer-core

The theoretical spatial power spectrum of a dipole located at ( r0, θ60, φ0) can be fitted by a straight line in logarithmic scale when n is larger than 2. Based on the spherical harmonic coefficients of geomagnetic field during 1900-1995, the depth( r0) of source-layer of every 5a is calculated. The results show that r0 decreased from 1900 to 1960; abruptly changed from 1945 to 1950 related to some kind of disturbance; decreased again from 1960 to 1975; increased from 1975 to 1985; and kept stable after 1985. Then the mean energy density (MED) of each year is induced to its corresponding r0. We find that MED of dipole field kept nearly unchanged from 1900 to 1960. While, MED of non-dipole field increased. The change of r0 coinciding with the geomagnetic secular variation, impulse and length-of-day happened around 1970, suggesting that the change of r0 may be related to the impulse. The variation in the fluid flow in the outer-core caused by the core-mantle coupling is a plausible candidate in explaining the changes in geomagnetic Jerk, length-of-day, and r0.     

NMR and IR investigations of ternary inclusion complexes among β-cyclodextrin, rare earth metal ions, and naphthalenediamines

Ternary inclusion complexes β-cyclodextrin (β-CD), rare earth metal ions (YbCl₃, YCl₃), and 1,8-naphthalene- diamine/1,5-naphthalenediamine are synthesized in basic aqueous media, which are characterized via ¹H NMR and IR spectroscopy. The stoichiometric proportion of β-CD:YbCl₃:1,5-naphthalenediamine is 2:1:2, that of β-CD:YCl₃:1,8-naphthalenediamine is 2:1:1, and that of β-CD:YbCl₃:1,8-naphthalenediamine is 2:1:1. The IR spectroscopy of the ternary inclusion complexes in the range of 935–1 000 cm⁻¹ reveals the existence of the coordinate bond M—O or M—N. The possible conformations of the ternary inclusion complexes are depicted. Biography: JIANG Huiming(1972–), male, Associate professor, research direction: molecular complex chemistry, supramolecular chemistry.     

Characterization of Anabaena cylindrica Solution System Using Synchronous-Scan Fluorescence Spectroscopy

The characterization of the algaeAnabaena cylindrica solution with Fe (III) was investigated using fluorescence emission and synchronous-scan spectroscopy. The ranges of concentrations of algae and Fe (III) in aqueous solutions were 5.0×10⁸ 2.5×10⁸ cell/L and 1060 μmol/L. respectively. The effective characterization method used was synchronous-scan fluorescence spectroscopy (SFS). The wavelength difference (Δλ) of 90 nm, was maintained between excitation wavelength (λen) and emission wavelength (λen). The peak was observed at about (λex) (λem) 326 nm for synchronous scan fluorescence spectroscopy. The fluorescence quenching in system of algae Fe(III)-HA was studied using synchronous-scan spectroscopy for the first time, Fe(III) was clearly the effective quencher. The relationship betweenI I (quenching efficiency) andc (concentration of Fe (III) added) was, a linear correlation for the algae solution with Fe(III). Also, Aldrich humie acid (HA) was found to be an effective quencher. Foundation item: Supported by the National Natural Science Foundation of China (20177017) and the Scientific Research Foundation of Wuhan Environmental Protection Bureau Biography: LIU Xian li(1965), male. Ph.D. Associate professor, research direction: environmental chemistry.     

Oligocarpia kepingensis sp. nov. from the Lower Permian of the northern Tarim Basin, Xinjiang and itsin situ spores

A Palaeozoic gleicheniaceous fernOligocarpia kepingensis sp. nov. is described from the Lower Permian of the northern Tarim Basin, Xinjiang, China. The material comprises fertile organs including sori, sporangia, spores and associated sterile leaf of theSphenopteris type. The sori are circular and 0.6–0.8 mm in diameter, and each sorus consists of 4–6 oval sporangia without an indusium. A transverse annulus completely encircles the sporangium. Each sporangium produces probably 256 trilete spores resembling the dispersed genusLeiotriletes. Comparisons are made betweenO. kepingensis and other species ofOligocarpia in the soral organization and spores. It is reasonable to includeOligocarpia in Gleicheniaceae based on its similarities of fertile character to the extant gleicheniaceous members.     

Synoptic-scale variation of δ18O in summer monsoon rainfall at Lijiang, China

Based on the daily δ~(18)O data in June―September 2003 at Lijiang and the daily mean NCEP/ NCAR reanalysis data, synoptic-scale variation of δ~(18)O in summer monsoon rainfall was investigated. The 'precipitation amount effect' is obvious for the daily δ~(18)O variation, whereas the 'temperature effect' is insignificant. Alternate occurrences of active phase and break phase of the southwest monsoon probably influence the synoptic-scale δ~(18)O variation prominently. Moreover, the isotopic composition in precipitation during the late monsoon months is presumably influenced significantly by recycling of monsoon precipitation. Both the above factors disturb the 'amount effect' of isotopic variation in the monsoon region. This study also indicates that the synoptic-scale rainfall δ~(18)O variation at Lijiang in summer is domi-nated by the Indian monsoon depression (low pressure) system at large scale. These results are important for further studying the 'amount effect' and reconstructing paleoclimate in the monsoon region.