人参果茎尖脱毒培养与快速繁殖

对人参果(Solanum muricatum Ait)茎尖进行离体培养及快速繁殖.结果表明:适于外植体生长分化的培养基是不加任何激素或只加0.2 mg*L-1 NAA的MS培养基;用MS 0.5 mg*L-1 NAA培养基能促进组培苗茎尖快速伸长,有利于茎尖的剥离和脱毒培养;适于茎尖愈伤组织形成和分化的培养基为MS 0.2 mg*L-1 NAA 2.0 mg*L-1 6-BA;适于壮苗快繁的培养基为MS 0.5 mg*L-1 NAA 0.1 mg*L-1 PP333.生物学和电镜检测结果表明,利用0.2～0.3 mm茎尖培养的人参果试管苗已脱除病毒.     

Bovine lactoferrin binds oleic acid to form an anti-tumor complex similar to HAMLET

α-Lactalbumin (α-LA) can bind oleic acid (OA) to form HAMLET-like complexes, which exhibited highly selective anti-tumor activity in vitro and in vivo. Considering the structural similarity to α-LA, we conjectured that lactoferrin (LF) could also bind OA to obtain a complex with anti-tumor activity. In this study, LF–OA was prepared and its activity and structural changes were compared with α-LA–OA. The anti-tumor activity was evaluated by methylene blue assay, while the apoptosis mechanism was analyzed using flow cytometry and Western blot. Structural changes of LF–OA were measured by fluorescence spectroscopy and circular dichroism. The interactions of OA with LF and α-LA were evaluated by isothermal titration calorimetry (ITC). LF–OA was obtained by heat-treatment at pH 8.0 with LD₅₀ of 4.88, 4.95 and 4.62 μM for HepG2, HT29, and MCF-7 cells, respectively, all of which were 10 times higher than those of α-LA–OA. Similar to HAMLET, LF–OA induced apoptosis in tumor cells through both death receptor- and mitochondrial-mediated pathways. Exposure of tryptophan residues and the hydrophobic regions as well as the loss of tertiary structure were observed in LF–OA. Besides these similarities, LF showed different secondary structure changes when compared with α-LA, with a decrease of α-helix and β-turn and an increase of β-sheet and random coil. ITC results showed that there was a higher binding number of OA to LF than to α-LA, while both of the proteins interacted with OA through van der Waals forces and hydrogen bonds. This study provides a theoretical basis for further exploration of protein–OA complexes.     

Catabolism of 1,3-dinitrobenzene by Rhodococcus sp. QT-1

The 1,3-dinitrobenzene-degrading Rhodococcus strain QT-1 was isolated under nitrogen limiting conditions from contaminated soil samples. Experimental data indicate that 1,3-dinitrobenzene is metabolized via 4-nitrocatechol. Both compounds were oxidized by resting cells and nitro groups were completely eliminated as nitrite. Strain QT-1 utilizes both 1,3-dinitrobenzene and 4-nitrocatechol as source of nitrogen in the absence as well as in the presence of high amounts of ammonia. Growth on 4-nitrocatechol does not induce the enzyme(s) for the initial oxidation of 1,3-dinitrobenzene.Abbreviations TNT 2,4,6-trinitrotoluene - 1,3DNB 1,3-dinitrobenzene - 4NC 4-nitrocatechol - 3NA 3-nitroaniline - NB nutrient broth; t_d doubling time - OD₅₄₆ optical density at 546 nm     

Genome downsizing in polyploid plants

All else being equal, polyploids are expected to have larger C-values (amount of DNA in the unreplicated gametic nucleus) than their diploid progenitors, increasing in direct proportion with ploidy. This expectation is observed in some polyploid series, especially those newly formed, but there are examples suggesting that C-values in particular polyploids are less than expected. The availability of the Angiosperm DNA C-values database ( http://www.rbgkew.org.uk/cval/homepage.html ) has allowed this question to be addressed across a broad range of angiosperms and has revealed striking results deviating from expectation: (i) mean 1C DNA amount did not increase in direct proportion with ploidy, and (ii) mean DNA amount per basic genome (calculated by dividing the 2C value by ploidy) tended to decrease with increasing ploidy. These results suggest that loss of DNA following polyploid formation, or genome downsizing, may be a widespread phenomenon of considerable biological significance. Recent advances in our understanding of the molecular events that take place following polyploid formation together with new data on how DNA amounts can both increase and decrease provide some insights into how genome downsizing may take place. The nature of the evolutionary forces that may be driving DNA loss are also discussed.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 651–663.     

The Effect of Adriamycin Exposure on the Notochord of Mouse Embryos

The notochord has important structural and signaling properties during vertebrate development with key roles in patterning surrounding tissues, including the foregut. The adriamycin mouse model is an established model of foregut anomalies where exposure of embryos in utero to the drug adriamycin leads to malformations including oesophageal atresia and tracheoesophageal fistula. In addition to foregut abnormalities, treatment also causes branching, displacement, and hypertrophy of the notochord. Here, we explore the hypothesis that the notochord may be a primary target of disruption leading to abnormal patterning of the foregut by examining notochord position and structure in early embryos following adriamycin exposure. Treated (n = 46) and control (n = 30) embryos were examined during the crucial period when the notochord normally delaminates away from the foregut endoderm (6–28 somite pairs). Transverse sections were derived from the anterior foregut and analyzed by confocal microscopy following immunodetection of extracellular matrix markers E‐cadherin and Laminin. In adriamycin‐treated embryos across all stages, the notochord was abnormally displaced ventrally with prolonged attachment to the foregut endoderm. While E‐cadherin was normally detected in the foregut endoderm with no expression in the notochord of control embryos, treated embryos up to 24 somites showed ectopic notochordal expression indicating a change in characteristics of the tissue; specifically an increase in intracellular adhesiveness, which may be instrumental in structural changes, affecting mechanical and signaling properties. This is consistent with disruption of the notochord leading to altered signaling to the foregut causing abnormal patterning and congenital foregut malformations.     

基于小波分析的医学图像的处理

医学图像的好坏直接影响着医生对病情的诊断和治疗,因此利用数字图像处理等技术对医学图像进行有效的处理,已成为医学图像处理研究和开发的一大热点.小波分析是对傅立叶变换的继承和发展,在医学影像领域有着广阔的应用前景.介绍了二维离散小波变换的一般形式,在图像分解的基础上,利用小波分析对医学图像进行去噪和增强处理,能够有效的改善图像质量,有利于医生对病情的诊断和治疗.     

Cadmium regulation by Lasius niger: A contribution to understanding high metal levels in ants

Ants (Formicinae, Hymenoptera) are considered efficient accumulators of Zn and Cd. In this study the relationship between Cd concentrations in soil and in Lasius niger workers was assessed for 20 colonies located along a gradient of Cd pollution. As soil Cd concentration increased from 1 to 8 mg/kg, ant body Cd concentration increased rapidly to about 40 mg/kg, and remained stable at this level, through a progressive increase of soil Cd concentration from 8 to 21 mg/kg. The phase of rapid increase confirms the high ability of L. niger for Cd accumulation, while the stabilization of Cd body concentration indicates either increasing elimination rate or decreasing rate of uptake. Therefore it can be concluded that Lasius niger has a high ability to accumulate Cd, but simultaneously an ability for Cd regulation was detected.     

The nematode Oscheius tipulae as a genetic model for programmed DNA elimination

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