Dictyoclostus cf.neoinflatus Licharew的拟内疹

有铰纲腕足动物的壳壁疹孔,具有分类及生态方面的意义。十九世纪中叶,M.D.Carpenter(1853)用光学显微镜,观察了穿孔贝类的壳壁穿孔。以后,K.M.Hatai(1940)、P.E.Cloud(1942)以及A.Williams(1956,1965)等,对此类构造均作过描述,并称之为内疹(Endopuncta)。1968年Williams利用电子显微镜,研究了现代穿孔贝内疹的超微形态,并对其成因和功能作了较详细的探讨。     

Spectroscopic properties of ironthiosemicarbazone compounds. Structure of [Fe(C7H7N4S)2]·1.25H2O

The reaction of FeCl₃ and HL, where HL=C₇H₈N₄S, pyridine-2-carbaldehyde thiosemicarbazone, at physiological pH values in air gives rise to a powder of composition C₁₄H₁₆Cl_0.3FeN₈O_1.2S₂ which contains iron(II)- and iron(III)-thiosemicarbazone species. This fact confirms the reducing character of the ligand in neutral and basic media. The [Fe(C₇H₇N₄S)₂]·1.25H₂O compound has been isolated. The crystal structure consists of discrete monomeric cationic entities containing low-spin iron(II) ions in a distorted octahedral environment. The metal ion is bonded to one sulfur and two nitrogen atoms of each thiosemicarbazone molecule. The powdered X-band EPR spectra of C₁₄H₁₆Cl_0.3FeN₈O_1.2S₂ show a significant variation with temperature which can be explained considering an ‘exchange narrowing’ phenomenon, in good accordance with the presence of antiferromagnetic interactions. The Mössbauer measurements are in good agreement with the existence of one iron(II) and two iron(III) low-spin species, with relative areas of 69, 17 and 14%, respectively.     

Production of fertile somatic hybrids of Gossypium hirsutum?+?G. bickii and G. hirsutum?+?G. stockii via protoplast fusion

Fertile somatic hybrids were obtained via symmetric electrofusion of protoplasts from two combinations of tetraploid cotton (G. hirsutum cv. Coker 201, AD genome) and diploid wild cottons G. bickii (G genome) and G. stockii (E genome), respectively. Observation by morphological, flow cytometric analysis, chromosome counting and RAPD analysis of the tested hybrids of Coker 201 + G. bickii and Coker 201 + G. stockii confirmed the regenerated plants as hybrid status. Cytological investigation of the metaphase root-tip cells revealed there were 78 chromosomes in the hybrids. Flow cytometric analysis showed the tested plants had a relative DNA contents close to the total DNA contents of the two parents. RAPD analysis revealed the hybrids contained specific genomic fragments from both fusion partners, further confirmed their hybridity. The morphology of the hybrids was intermediate between the two fusion partners. The hybrid plants were successfully transferred to the soil, and they bloomed and set bolls. It is sure that the new hexaploids developed by cell fusion would contribute to cotton breeding through backcrossing with the elite genotypes of G. hirsutum.     

Myxococcus sp.V11海藻糖合酶TreS II分子改造 *

来源于黏细菌Myxococcus sp.V11的海藻糖合酶(trehalose synthase, EC 2.4.1.245)TreS II可通过转糖苷作用将麦芽糖转化成为海藻糖,在酶法生产海藻糖上显示出一定的应用潜力,但TreS II对热敏感,在60℃保温3h,酶活性丧失,限制了其应用范围.目的:拟探索TreS II影响热稳定性的氨基酸残基构成,通过对可能的氨基酸位点进行定点突变,以期获得耐热性的突变子,扩大TreS II应用范围.方法: 通过PCR介导的方法对TreS II可能影响到热稳定性的氨基酸Q3,A283,W374,R449和Y537进行定点突变,以野生型重组酶为对照,比较突变型与野生型的最适反应温度和最适反应pH,通过测定不同温度下保存不同时间后的残留酶活,检测突变子的耐热效果.结果: 研究表明突变子Q3D,A283R,W374D,R449Q和Y537H的比酶活与野生型无显著差异,且最适pH 和最适反应温度也未发生改变;A283R,Y537H在60℃条件下,3h后活性剩余68%;Q3D,W374D,R449Q在温度60℃时,3h后活性剩余35%.结论: TreS II分子结构中与金属离子结合的几个氨基酸残基的改变对蛋白质分子的耐热性具有显著影响.     

Photosynthesis of Ulva sp. II. utilization of CO2 and HCO−3 when submerged

The photosynthetic capacity of submerged Ulva sp. when utilizing CO₂ and HCO^?₃ as exogenous carbon forms has been investigated and compared with ambient carbon concentrations in sea water. Saturating concentrations of HCO^{? ₃} and CO₂ were 1200 and 100 μM, respectively at saturating light, and photosynthetic rates under such conditions averaged 700 μmolO₂·gDW^?1 ·h^?1. The HCO^?₃ concentration of sea water (≈2500μM), was thus found to be saturating for photosynthesis of Ulva. At the CO₂ concentration of sea water (≈ 10 μM), the contribution of this carbon form to photosynthesis could be 27% at the most. Under conditions of slow water movement, the relative importance of CO₂ utilization would probably be minimized in favour of HCO^?₃ utilization. It is concluded that HCO^?₃ uptake is not limiting photosynthesis for Ulva under natural conditions.     

Syntheses and crystal structures of the first iridium complexes with m- and p-terphenyl (tp). {[Ir2(p-tp)(cod)2](BF4)2 · 2CH2Cl2}3 and [Ir(m-tp)(η-C5Me5)](BF4)2

Novel two iridium terphenyl complexes were prepared and their structures were characterized crystallographically. The reaction of [Ir(cod)₂]BF₄ with p-terphenyl (p-tp) in CH₂Cl₂ was carried out to afford dinuclear Ir(I) complex {[Ir₂(p-tp)(cod)₂](BF₄)₂ · 2CH₂Cl₂}₃ (cod=1,5-cyclooctadiene) (1 · 2CH₂Cl₂), whereas the reaction of the intermediate [Ir(η⁵-C₅Me₅)(Me₂CO)₃]³⁺ in Me₂CO with m-terphenyl (m-tp) was done to provide mononuclear Ir(III) complex [Ir(m-tp)(η⁵-C₅Me₅)](BF₄)₂ (2). In complex 1 · 2CH₂Cl₂, two Ir atoms are η⁶-coordinated to both sides of terminal benzene rings from the upper and lower sides in the p-tp ligand, while one Ir atom is η⁶-coordinated to one side of the terminal benzene ring in the m-tp ligand in complex 2. Each crystal structure describes the first coordination mode found in metal complexes with the m- and p-tp ligands.