Different competitive outcomes among four species of cladocerans under different alga combinations of colonial <Emphasis Type="Italic">Microcystis</Emphasis> spp. and green alga <Emphasis Type="Italic">Scenedesmus obliquus</Emphasis>

Cyanobacteria blooms (especially Microcystis spp.) are thought to alter dominance of large-sized daphnids into small-sized metazoan zooplankton. However, several field investigations show different phenomena. Laboratory experiments were conducted based on the hypothesis that different Microcystis spp. concentrations would influence competitive outcomes using two algal combinations of different concentrations and four species of cladocerans. In the algal combination of 50 mg l⁻¹ colonial Microcystis spp. + 1 mg l⁻¹ Scenedesmus obliquus (fresh weight), Daphnia carinata was absent during the experiment in competition with other cladocerans. Decreasing colonial Microcystis spp. concentration (10 mg l⁻¹) resulted in a shift from dominance by small-sized cladocerans to dominance by D. carinata. No significant effects of different concentrations of colonial Microcystis spp. on competitive outcomes were shown among three small-sized cladocerans. These results support the idea that cyanobacteria concentration affects the dominance status of large-bodied daphnid.     

Homochiral metal-organic coordination networks from l-typtophan

Three homochiral metal-organic coordination networks [Co₂(l-Trp)₂(Py)₆] · Py · (ClO₄)₂ (1), [Ni(l-Trp)(Py)₃] · H₂O · ClO₄ (2) and [Co₂(l-Trp)(INT)₂(H₂O)₂(ClO₄)] (3), all containing natural amino acid l-HTrp (l-typtophan), were hydrothermally synthesized and structurally characterized. The compounds 1 and 2 crystallize in the orthorhombic space group C222₁, with a = 10.731(2) Å, b = 19.709(4) Å, c = 27.365(6) Å and Z = 4 for 1 and a = 10.710(10) Å, b = 20.088(18) Å, c = 27.63(3) Å and Z = 8 for 2, respectively. The compound 3 has the monoclinic space group P2₁, with a = 8.1934(14) Å, b = 13.209(2) Å, c = 12.464(2) Å, β = 104.107(3)° and Z = 2. Both 1 and 2 consist of 1D helical chains. Compound 3 is composed of 2D networks, which further assemble into a 3D supramolecular structure via weak interlayer interactions. The optically pure amino acid l-HTrp plays an important role leading to homochiral structures reported here.     

Generation and selection of immunized Fab phage display library against human B cell lymphoma

The approval of using monoclonal antibodies as a targeted therapy in the management of patients with B cell lymphoma has led to new treatment options for this group of patients. Production ofmonoclonal antibodies by the traditional hybridoma technology is costly, and the resulting murine antibodies often have the disadvantage of triggering human anti-mouse antibody （HAMA） response. Therefore recombinant Fab antibodies generated by the phage display technology can be a suitable alternative in managing B cell lymphoma. In this study, we extracted total RNA from spleen cells of BALB/c mice immunized with human B lymphoma cells, and used RT-PCR to amplify cDNAs coding for the κ light chains and Fd fragments of heavy chains. After appropriate restriction digests, these cDNA fragments were successively inserted into the phagemid vector pComb3H-SS to construct an immunized Fab phage display library. The diversity of the constructed library was approximately 1.94× 10^7. Following five rounds of biopanning, soluble Fab antibodies were produced from positive clones identified by ELISA. From eight positive clones, FabC06, FabC21, FabC43 and FabC59 were selected for sequence analysis. At the level of amino acid sequences, the variable heavy domains （VH） and variable light domains （VL） were found to share 88-92% and 89-94% homology with sequences coded by the corresponding murine germline genes respectively. Furthermore, reactivity with membrane proteins of the B cell lymphoma was demonstrated by immunohistochemistry and western blotting. These immunized Fab antibodies may provide a valuable tool for further study of B cell lymphoma and could also contribute to the improvement of disease therapy.     

人胎儿卵巢异种移植的组织学研究

目的探讨人胎儿卵巢组织异体移植的最佳条件。方法观察胎儿卵巢进行异种移植后的组织学变化,并计算各组移植卵巢内各期卵泡的发育情况及卵泡构成比。结果新鲜的卵巢组织、体外培养的卵巢组织以及冷冻复苏后经体外培养的卵巢组织移植后,其内有原始卵泡发育,而且可见丰富的血管网;未见明显的淋巴细胞浸润现象。结论人胎儿卵巢组织(包括新鲜的卵巢组织、体外培养的卵巢组织以及冷冻复苏后经体外培养的卵巢组织)异种移植后原始卵泡在受体体内能进一步发育,生长卵泡分泌的雌激素有调节子宫内膜周期性变化的作用。     

GFAP启动子调控的双顺反子真核表达载体pGFAP-IRES2-EGFP-p27的构建及表达分析

目的构建并鉴定带GFAP启动子的Flag-p27和EGFP双顺反子真核表达载体,观察其表达。方法利用IRES和GFAP启动子,通过质粒抽提、琼脂糖凝胶电泳、酶切、连接、转化等多种基因工程技术,经多步亚克隆后完成能同时表达p27和EGFP基因的星形胶质细胞特异性真核表达载体pGFAP-IRES2-EGFP-p27。转染体外培养的星形胶质细胞,观察EGFP的表达,并通过免疫荧光细胞化学技术观察p27的表达。结果经酶切鉴定和测序鉴定,成功构建真核表达载体pGFAP-IRES2-EGFP-p27。转染星形胶质细胞后可见EGFP的表达,并且在EGFP阳性的细胞中P27表达水平明显增高。结论GFAP启动子能启动目的基因p27和EGFP在星形胶质细胞的表达,连于Flag-p27的下游EGFP可作为报告基因,指示p27的表达情况。带启动子GFAP的Flag-p27和EGFP双顺反子真核表达载体的构建为进一步研究星形胶质细胞增生与神经系统疾病的关系,并为寻找神经系统疾病的有效基因治疗途径奠定基础。     

慢性胃炎肠化生CD_(44)、CD_(44V6)及Cyclin D_1、Cyclin E的表达和意义

目的探讨慢性胃炎胃粘膜肠化生CD44、CD44V6及cyclin D1、Cyclin E表达的意义。方法利用免疫细胞化学技术对39例伴有肠化生的慢性胃炎和5例正常人胃窦粘膜的活检组织进行检查。结果正常人胃窦粘膜上皮,腺上皮对CD44、CD44V6、Cyclin D1和Cyclin E均为阴性,但在有神经内分泌样细胞的粘膜,CD44V6和cyclin D1为阳性。慢性胃炎肠化生区和不典型增生区除CD44为阴性外,CD44V6、cyclin D1和cyclin E均呈现不同的阳性反应,但未见有阳性的神经内分泌样细胞。间质细胞大都呈阳性反应。结论CD44V6、cyclin D1和cyclin E可能是胃癌前状态的早期事件,而CD44可能为胃癌晚期的标志物。     

Synthesis and bioevaluation of N-(arylalkyl)-homospermidine conjugates

N1-(Arylalkyl)homospermidines (1c-1f) and terminally piperazine-substituted homospermidine conjugates (2a-2e) were synthesized and evaluated for cytotoxicity in mouse leukemia L1210, alpha-difluoromethylornithine (DFMO)-treated L1210, melanoma B16, spermidine (SPD)-treated B16, and HeLa cell lines. Results demonstrated that homospermidine was a more effective vector than piperazine-substituted homospermidine in ferrying diverse arenes into cells via the polyamine transporter. The leading compound, 9-anthracenemethyl-homospermidine (1a), was shown to induce apoptosis in B16 cells and IL-3 dependent FL5.12A pro-B cells. The novel conjugate 4-biphenylmethyl-homospermidine (1e) could also induce apoptosis. However, it exhibited different effect on the cell cycle of B16 cells compared to 1a.     

Dcr-1 maintains Drosophila ovarian stem cells

MicroRNAs (miRNAs) regulate gene expression by controlling the turnover, translation, or both of specific mRNAs. In Drosophila, Dicer-1 (Dcr-1) is essential for generating mature miRNAs from their corresponding precursors. Because miRNAs are known to modulate developmental events, such as cell fate determination and maintenance in many species, we investigated whether a lack of Dcr-1 would affect the maintenance of stem cells (germline stem cells, GSCs; somatic stem cells, SSCs) in the Drosophila ovary by specifically removing its function from the stem cells. Our results show that dcr-1 mutant GSCs cannot be maintained and are lost rapidly from the niche without discernable features of cell death, indicating that Dcr-1 controls GSC self-renewal but not survival. bag of marbles (bam), the gene that encodes an important differentiating factor in the Drosophila germline, however, is not upregulated in dcr-1 mutant GSCs, and its removal does not slow down dcr-1 mutant GSC loss, suggesting that Dcr-1 controls GSC self-renewal by repressing a Bam-independent differentiation pathway. Furthermore, Dcr-1 is also essential for the maintenance of SSCs in the Drosophila ovary. Our data suggest that miRNAs produced by Dcr-1 are required for maintaining two types of stem cells in the Drosophila ovary.     

Soybean oil methyl esters preparation using NaX zeolites loaded with KOH as a heterogeneous catalyst

The transesterification of soybean oil with methanol to methyl esters was carried out using NaX zeolites loaded with KOH as a solid base catalyst. Best result was obtained with NaX zeolite loaded with 10% KOH, followed by heating at 393 K for 3 h. When the transesterification reaction was carried out at reflux of methanol (338 K), with a 10:1 molar ratio of methanol to soybean oil, a reaction time of 8 h and a catalyst amount of 3 wt.%, the conversion of soybean oil was 85.6%.