水稻原生质体制备条件的优化及其细胞壁变化的快速检测

以疣粒野生稻和栽培稻02428的成熟种子为材料,对愈伤组织的诱导和继代、胚性悬浮细胞系建立、原生质体制备、再生细胞团分化及植株再生进行研究。结果表明：（1）水稻愈伤组织诱导的最佳2,4-D浓度为0.014 mmol/L;（2）胚性悬浮细胞系建立的最佳条件为AA 悬浮培养基+ 0.009 mmol/L 2,4-D ,每25 mL液体培养基加入0.4 g愈伤组织的初始接种量,7 d的继代周期;（3）原生质体制备的最佳条件为20 g/L纤维素酶+ 1 g/L果胶酶,酶解5 h,800 r/min离心5 min;（4）用荧光增白剂（VBL）细胞壁染色液可以快速、准确的检测原生质体制备及培养过程中细胞壁的变化情况。     

Induction medium osmolality improves microspore embryogenesis in wheat and triticale

The objective of this study was to determine the effect of induction medium osmolality on embryogenesis and green plant production in wheat and triticale. Isolated microspores of wheat and triticale were subjected to a range of osmolality (300–500 mOsm kg^?1) using mannitol. In both species, the maximum number of embryo-like structures (ELS) and green plants were obtained at 350 mOsm kg^?1 when the induction medium was supplemented with 9.1 g L^?1 of mannitol. A sharp decline in microspore response was observed at higher osmolality. These results demonstrate the effect of osmolality on induction of ELS and production of green plants indicating that the process of microspore embryogenesis can be improved in wheat and triticale by increasing osmolality of the induction medium to 350 mOsm kg^?1.     

Duplication of Genes in an ATP-binding Cassette Transport System Increases Dynamic Range While Maintaining Ligand Specificity

Many bacteria exist in a state of feast or famine where high nutrient availability leads to periods of growth followed by nutrient scarcity and growth stagnation. To adapt to the constantly changing nutrient flux, metabolite acquisition systems must be able to function over a broad range. This, however, creates difficulties as nutrient concentrations vary over many orders of magnitude, requiring metabolite acquisition systems to simultaneously balance ligand specificity and the dynamic range in which a response to a metabolite is elicited. Here we present how a gene duplication of a periplasmic binding protein in a mannose ATP-binding cassette transport system potentially resolves this dilemma through gene functionalization. Determination of ligand binding affinities and specificities of the gene duplicates with fluorescence and circular dichroism demonstrates that although the binding specificity is maintained the K_d values for the same ligand differ over three orders of magnitude. These results suggest that this metabolite acquisition system can transport ligand at both low and high environmental concentrations while preventing saturation with related and less preferentially metabolized compounds. The x-ray crystal structures of the β-mannose-bound proteins help clarify the structural basis of gene functionalization and reveal that affinity and specificity are potentially encoded in different regions of the binding site. These studies suggest a possible functional role and adaptive advantage for the presence of two periplasmic-binding proteins in ATP-binding cassette transport systems and a way bacteria can adapt to varying nutrient flux through functionalization of gene duplicates.     

Characterization of evolving biomechanical properties of tissue engineered vascular grafts in the arterial circulation

We used a murine model to assess the evolving biomechanical properties of tissue engineered vascular grafts (TEVGs) implanted in the arterial circulation. The initial polymeric tubular scaffold was fabricated from poly(lactic acid)(PLA) and coated with a 50:50 copolymer of poly(caprolactone) and poly(lactic acid)(P[PC/LA]). Following seeding with syngeneic bone marrow derived mononuclear cells, TEVGs (n=50) were implanted as aortic interposition grafts in wild-type mice and monitored serially using ultrasound. A custom biaxial mechanical testing device was used to quantify the in vitro circumferential and axial mechanical properties of grafts explanted at 3 or 7 months. At both times, TEVGs were much stiffer than native tissue in both directions. Repeated mechanical testing of some TEVGs treated with elastase or collagenase suggested that elastin did not contribute significantly to the overall stiffness whereas collagen did contribute. Traditional histology and immunostaining revealed smooth muscle cell layers, significant collagen deposition, and increasing elastin production in addition to considerable scaffold at both 3 and 7 months, which likely dominated the high stiffness seen in mechanical testing. These results suggest that PLA has inadequate in vivo degradation, which impairs cell-mediated development of vascular neotissue having properties closer to native arteries. Assessing contributions of individual components, such as elastin and collagen, to the developing neovessel is needed to guide computational modeling that may help to optimize the design of the TEVG.     

Characterization of a Subtropical Hawksbill Sea Turtle (Eretmocheyles imbricata) Assemblage Utilizing Shallow Water Natural and Artificial Habitats in the Florida Keys

In order to provide information to better inform management decisions and direct further research, vessel-based visual transects, snorkel transects, and in-water capture techniques were used to characterize hawksbill sea turtles in the shallow marine habitats of a Marine Protected Area (MPA), the Key West National Wildlife Refuge in the Florida Keys. Hawksbills were found in hardbottom and seagrass dominated habitats throughout the Refuge, and on man-made rubble structures in the Northwest Channel near Cottrell Key. Hawksbills captured (N = 82) were exclusively juveniles and subadults with a straight standard carapace length (SSCL) ranging from 21.4 to 69.0cm with a mean of 44.1 cm (SD = 10.8). Somatic growth rates were calculated from 15 recaptured turtles with periods at large ranging from 51 to 1188 days. Mean SSCL growth rate was 7.7 cm/year (SD = 4.6). Juvenile hawksbills (<50 cm SSCL) showed a significantly higher growth rate (9.2 cm/year, SD = 4.5, N = 11) than subadult hawksbills (50–70 cm SSCL, 3.6 cm/year, SD = 0.9, N = 4). Analysis of 740 base pair mitochondrial control region sequences from 50 sampled turtles yielded 12 haplotypes. Haplotype frequencies were significantly different compared to four other Caribbean juvenile foraging aggregations, including one off the Atlantic coast of Florida. Many-to-one mixed stock analysis indicated Mexico as the primary source of juveniles in the region and also suggested that the Refuge may serve as important developmental habitat for the Cuban nesting aggregation. Serum testosterone radioimmunoassay results from 33 individuals indicated a female biased sex ratio of 3.3 females: 1 male for hawksbills in the Refuge. This assemblage of hawksbills is near the northern limit of the species range, and is one of only two such assemblages described in the waters of the continental United States. Since this assemblage resides in an MPA with intensive human use, basic information on the assemblage is vital to resource managers charged with conservation and species protection in the MPA.     

Influence of drainage divides versus arid corridors on genetic structure and demography of a widespread freshwater turtle,Emydura macquarii krefftii,from Australia

The influence of Pleistocene climatic cycles on Southern Hemisphere biotas is not yet well understood. Australia's eastern coastal margin provides an ideal setting for examining the relative influence of landscape development, sea level fluctuation, and cyclic climatic aridity on the evolution of freshwater biodiversity. We examined the impact of climatic oscillations and physical biogeographic barriers on the evolutionary history of the wide‐ranging Krefft's river turtle (Emydura macquarii krefftii), using range‐wide sampling (649 individuals representing 18 locations across 11 drainages) and analysis of mitochondrial sequences (~1.3‐kb control region and ND4) and nuclear microsatellites (12 polymorphic loci). A range of phylogeographic (haplotype networks, molecular dating), demographic (neutrality tests, mismatch distributions), and population genetic analyses (pairwise F_ST, analysis of molecular variance, Bayesian clustering analysis) were implemented to differentiate between competing demographic (local persistence vs. range expansion) and biogeographic (arid corridor vs. drainage divide) scenarios. Genetic data reveal population genetic structure in Krefft's river turtles primarily reflects isolation across drainage divides. Striking north‐south regional divergence (2.2% ND4 p‐distance; c. 4.73 Ma, 95% higher posterior density (HPD) 2.08–8.16 Ma) was consistent with long‐term isolation across a major drainage divide, not an adjacent arid corridor. Ancient divergence among regional lineages implies persistence of northern Krefft's populations despite the recurrent phases of severe local aridity, but with very low contemporary genetic diversity. Stable demography and high levels of genetic diversity are inferred for southern populations, where aridity was less extreme. Range‐wide genetic structure in Krefft's river turtles reflects contemporary and historical drainage architecture, although regional differences in the extent of Plio–Pleistocene climatic aridity may be reflected in current levels of genetic diversity.     

两株四环素降解菌的分离鉴定及降解条件优化

为发掘四环素高效降解菌株,本研究从以四环素为唯一生长碳源的养鸡场粪便堆肥样品中分离筛选到2株四环素降解菌TC-04和TC-09,并通过形态特征、生理生化特征和16SrRNA基因序列分析,对其进行鉴定.采用单因素试验分别探究不同碳源、氮源、微量元素这3个培养基成分和培养时间、接种量和装液量这3个培养条件对两株菌降解四环素...     

五节芒定居对尾矿砂重金属形态、微生物群落功能及多样性的影响

选择尾矿砂裸地和4个五节芒(Miscanthus floridulus)定居地(RI、RII、RIII和RIV)为样地, 分别研究了五节芒定居对尾矿砂重金属形态转化和微生物功能参数的影响。结果表明: 五节芒自然定居显著地提高了尾矿砂碳酸盐结合态和硫化物-有机物结合态重金属比例(p＜0.05), 降低了尾矿砂残渣态重金属的比例(p＜0.05)。土壤微生物群落的纤维素分解作用、酚转化作用、固氮作用、氨化作用、硝化作用、有机磷转化作用、功能多样性、4类不同碳源(碳水化合(CH)、聚合物(PL)、胺类化合物(AM)和杂合物(ML))均随着五节芒自然定居显著提高(p＜0.05)。而氨基酸(AA)的利用强度却显著下降(p＜0.05)。典范相关分析(CCA)表明: 土壤微生物功能参数的总体变化与土壤碳酸盐结合态和硫化物-有机物结合态重金属的含量呈显著正相关, 与残渣态重金属含量呈显著负相关。该研究结果表明, 五节芒定居不仅促进了尾矿砂重金属朝着沉淀态和螯合态方面转化, 而且还显著地改善了尾矿砂微生物群落的功能发挥。因而, 五节芒在重金属矿业废弃地恢复实践中具有较大的应用潜力。     

福建三明不同更新方式的米槠林物种多样性研究

本文从α多样性尺度总结三种不同更新方式的米槠林群落的物种多样性状况。结果表明,不同更新方式的米槠林群落中,物种丰富度、多样性指数和均匀度表现为天然更新> 人促更新> 人工造林。天然更新和人促更新米槠林是在皆伐迹上未经炼山发育起来的群落,而人工造林米槠林是从火烧迹地上发育的。天然更新米槠林处于演替的中级阶段,未达到顶级群落;而人促更新和人工造林米槠林则处于衰退阶段。     

中国肩花蝽属雌性交配管的形态研究

半翅目花蝽科（Anthocoridae） 昆虫的种类鉴定通常是以雄性外生殖器特征为主, 雌虫的种类鉴定一直是研究中的难点。本文研究了中国肩花蝽属 Tetraphleps 已知5个种雌虫的交配管,包括黑色肩花蝽T. aterrimus (Sahlberg)、斑翅肩花蝽T. galchanoides Ghauri、毛肩花蝽T. pilosulus Bu et Zheng、直长肩花蝽T. parallelus Bu et Zheng和玉龙肩花蝽T. yulongensis Bu et Zheng。发现交配管的构造在种内变异小、特征稳定,而在种间差别明显,可作为该属雌虫种类鉴定的可靠依据。