A conserved karyotype of Sternopygus macrurus (Sternopygidae, Gymnotiformes) in the Amazon region: differences from other hydrographic basins suggest cryptic speciation

We studied the karyotypes of 35 Sternopygus macrurus fishes of four localities from rivers of the Eastern Amazon basin. In these four places the karyotypes have 2n = 46 chromosomes, NF = 92, where 30 are metacentric (M) and 16 submetacentric (SM). The constitutive heterochromatin (CH) is found in the centromeric region of most chromosomes and in the pericentromeric region of pairs 5, 17 and 19. Pair 1 has a large and not common heterochromatic block in the short arm, useful as a marker for this species if not found in other Sternopygus taxa. The NOR is located in the distal region of the short arm of pair 1, showing a size heteromorphism in some specimens. The CMA₃ and DAPI fluorochrome bandings and the fluorescent in situ hybridization (FISH), using pantelomeric human probes techniques are described for the first time for this species. DAPI has banding coincident with the C-banded regions, which suggests that the CH is AT base-pair-rich. CMA₃ banding is coincident with the NOR, meaning that this region is GC base-pair-rich. The FISH showed that the probes hybridized only with the telomeric regions, without any sign of interstitial telomeric regions. The karyotype of the samples from different places in the Amazon basin is quite conserved, probably because of the gene flow among the populations. The karyotype differences among the Sternopygus macrurus from the Amazon basin and the São Francisco and Paraná rivers suggest that these taxa may be different species.     

Recent advances in rice genome and chromosome structure research by fluorescence in situ hybridization (FISH)

Fluorescence in situ hybridization (FISH) is an effective method for the physical mapping of genes and repetitive DNA sequences on chromosomes. Physical mapping of unique nucleotide sequences on specific rice chromosome regions was performed using a combination of chromosome identification and highly sensitive FISH. Increases in the detection sensitivity of smaller DNA sequences and improvements in spatial resolution have ushered in a new phase in FISH technology. Thus, it is now possible to perform in situ hybridization on somatic chromosomes, pachytene chromosomes, and even on extended DNA fibers (EDFs). Pachytene-FISH allows the integration of genetic linkage maps and quantitative chromosome maps. Visualization methods using FISH can reveal the spatial organization of the centromere, heterochromatin/euchromatin, and the terminal structures of rice chromosomes. Furthermore, EDF-FISH and the DNA combing technique can resolve a spatial distance of 1 kb between adjacent DNA sequences, and the detection of even a 300-bp target is now feasible. The copy numbers of various repetitive sequences and the sizes of various DNA molecules were quantitatively measured using the molecular combing technique. This review describes the significance of these advances in molecular cytology in rice and discusses future applications in plant studies using visualization techniques.     

Achieving the nitrite pathway using FA inhibition and process control in UASB-SBR system removing nitrogen from landfill leachate

An up-flow sludge blanket(UASB) and sequencing batch reactor(SBR) system was introduced to remove organics and nitrogen from landfill leachate.The synergetic effect of free ammonia(FA) inhibition and process control was used to achieve the nitrite pathway in the SBR.In previous research,inhibition of FA on nitrite oxidizing bacteria(NOB) activity has been revealed and the process control parameters(DO,ORP and pH) exactly indicate the end-point of nitritation.The method was implemented in the SBR achieving s...     

游离氨抑制协同过程控制实现渗滤液短程硝化

采用UASB-SBR生化系统处理高氮晚期渗滤液为研究对象,在获得稳定有机物和氮去除的前提下,考察了采用游离氨(FA)协同过程控制对实现渗滤液长期稳定短程硝化的可行性,建立实现与维持SBR系统内稳定短程硝化的途径及方法.试验结果表明:经过36d的运行,SBR系统的亚硝积累率始终稳定在90%以上,获得了稳定的短程硝化.游离氨和过程控制的协同作用是实现与维持SBR反应器稳定短程硝化的决定因素,以DO,ORP和pH作为渗滤液短程硝化反硝化的过程控制参数是可行的,在充分利用较高FA抑制亚硝酸盐氧化菌活性的前提下,过程控制能够准确判断硝化终点,避免过度曝气破坏短程硝化,从而为氨氧化菌(AOB)的生长创造有利条件,有效抑制亚硝酸盐氧化菌(NOB)的生长并逐渐从系统中淘洗出去,实现了硝化菌种群的优化,荧光原位杂交技术(FISH)检测也证明这一点.在此基础上,通过批次实验考察了微生物种群的反硝化动力学特性,符合Monod动力学方程,NO2--N基质最大比利用速率和半饱和常数分别为0.44gNO2--NgVSS-1d-1和15.8mgL-1.     

抑癌基因bcl-2在玉米染色体中的荧光原位杂交定位

以人的抑癌基因ｂｃｌ－２为探针,通过Ｓｏｕｔｈｅｒｎ杂交技术,发现ｂｃｌ－２在玉米和水稻的基因组中均具有同源序列;并运用荧光原位杂交技术,对玉米中的ｂｃｌ－２同源序列进行了定位．结果表明：ｂｃｌ－２在玉米第４号和第７号染色体上均检出了杂交信号,信号检出率分别为８．１６％和６．６３％．ｂｃｌ－２在第４号染色体长臂上的杂交信号与着丝粒的百分距离为５８．０７±４．９０,在第７号染色体长臂上的杂交信号与着丝粒的百分距离为８０．３４±３．１２．上述研究结果为研究植物细胞程序性死亡的可能调控机制提供了线索,将有利于进一步分析植物与动物细胞程序性死亡的相关性     

Microbial detection in microfluidic devices through dual staining of quantum dots-labeled immunoassay and RNA hybridization

This paper reported the development of a microfludic device for the rapid detection of viable and nonviable microbial cells through dual labeling by fluorescent in situ hybridization (FISH) and quantum dots (QDs)-labeled immunofluorescent assay (IFA). The coin sized device consists of a microchannel and filtering pillars (gap = 1-2 μm) and was demonstrated to effectively trap and concentrate microbial cells (i.e. Giardia lamblia). After sample injection, FISH probe solution and QDs-labeled antibody solution were sequentially pumped into the device to accelerate the fluorescent labeling reactions at optimized flow rates (i.e. 1 and 20 μL/min, respectively). After 2 min washing for each assay, the whole process could be finished within 30 min, with minimum consumption of labeling reagents and superior fluorescent signal intensity. The choice of QDs 525 for IFA resulted in bright and stable fluorescent signal, with minimum interference with the Cy3 signal from FISH detection.     

荧光原位杂交技术在活性污泥菌群识别中的研究进展

荧光原位杂交技术(FISH)广泛地应用于分析环境微生物的群落组成,能够同时对微生物进行定性、定量分析,并确定微生物群落空间分布情况.本文阐述了FISH法应用于活性污泥处理系统的重要作用,综述了FISH法在活性污泥及生物膜微生物菌群的组成、结构与功能的研究和应用,同时讨论了其在应用中存在的不足,并在此基础上总结了一系列可...     

Selected In Situ Hybridization Methods: Principles and Application

We are experiencing rapid progress in all types of imaging techniques used in the detection of various numbers and types of mutation. In situ hybridization (ISH) is the primary technique for the discovery of mutation agents, which are presented in a variety of cells. The ability of DNA to complementary bind is one of the main principles in every method used in ISH. From the first use of in situ techniques, scientists paid attention to the improvement of the probe design and detection, to enhance the fluorescent signal intensity and inhibition of cross-hybrid presence. This article discusses the individual types and modifications, and is focused on explaining the principles and limitations of ISH division on different types of probes. The article describes a design of probes for individual types of in situ hybridization (ISH), as well as the gradual combination of several laboratory procedures to achieve the highest possible sensitivity and to prevent undesirable events accompanying hybridization. The article also informs about applications of the methodology, in practice and in research, to detect cell to cell communication and principles of gene silencing, process of oncogenesis, and many other unknown processes taking place in organisms at the DNA/RNA level.     

动物细胞凋亡相关基因p53和c-myc在大麦中的染色体定位

以人的原癌基因c myc和抑癌基因p53的cDNA为探针,经Southern杂交证明,它们在大麦基因组中存在同源序列.利用荧光原位杂交技术(FISH)进一步对大麦进行了染色体定位.在大麦有丝分裂中期染色体上p53有3个位点被检出,分别位于2L(第二染色体长臂)、2S(第二染色体短臂)和6L上,相应百分距离为84.27±0.75、46.24±15.44和19.23±0.53;c myc有2个位点被检出,分别位于5L和3S上,百分距离相应为75.90±6.62和47.63±5.20.利用改进的荧光原位杂交技术,使异源单拷贝或低拷贝基因在大麦姐妹染色单体上,同时出现信号的检出率达到了30%以上.