Low nanogram detection of nucleotides using fast atom bombardment-mass spectrometry

The effect of trimethylsilyl (TMS) derivatization on detection limits of mononucleotides in fast atom bombardment-mass spectrometry (FAB-MS) was examined. FAB-MS methods were developed to optimize sensitivity using adenosine 5'-monophosphate as a model compound and then applied to reference standards of two clinically important nucleotides: tricyclic nucleoside-5'-monophosphate (TCNMP) and 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP). The detection limit for the TMS derivative of TCNMP was 2.5-5 ng/microliters and less than 2.5 ng/microliters for FdUMP as its TMS derivative. This is greater than two orders of magnitude more sensitive than the FAB-MS analysis of the corresponding free compounds. These low detection limits for the TMS derivatives were obtained using a narrow scan range, signal averaging, detection in the negative ion mode, and 3-nitrobenzyl alcohol as the matrix. Hydrolysis of one or more of the labile TMS groups did occur, with the extent of hydrolysis being greatest in the more protic matrices.     

A novel long non-coding RNA AC073352.1 promotes metastasis and angiogenesis via interacting with YBX1 in breast cancer

Breast cancer is the major cause of cancer death worldwide in women. Patients with metastasis have poor prognosis and the mechanisms of breast cancer metastasis are not completely understood. Long non-coding RNAs (lncRNAs) have been shown to have crucial roles in breast cancer development and progression. However, the underlying mechanisms by which lncRNA-driven breast cancer metastasis are unknown. The main objective of this paper is to explore a functional lncRNA and its mechanisms in breast cancer. Here we identified a novel lncRNA AC073352.1 that was significantly upregulated in breast cancer tissues and was associated with advanced TNM stages and poor prognosis in breast cancer patients. In addition, AC073352.1 was found to promote the migration and invasion of breast cancer cells in vitro and enhance breast cancer metastasis in vivo. Mechanistically, we elucidated that AC073352.1 interacted with YBX1 and stabilized its protein expression. Knock down of YBX1 reduced breast cancer cell migration and invasion and could partially reverse the stimulative effects of AC073352.1 overexpressed on breast cancer metastasis. Moreover, AC073352.1 might be packaged into exosomes by binding to YBX1 in breast cancer cells resulting in angiogenesis. Collectively, our results demonstrated that AC073352.1 promoted breast cancer metastasis and angiogenesis via binding YBX1, and it could serve as a promising, novel biomarker for prognosis and a therapeutic target in breast cancer.Subject terms: Breast cancer, Cell invasion, Long non-coding RNAs     

能量标签技术及其在红树林生态系统能流研究中的应用

传统上认为红树林输出的有机质产生巨大的能流,支持了巨大的河口和近岸水域生态系统的次级生产。但能量标签技术的研究结果却显示红树林输出的有机质的作用并没有如此巨大。用红树碎屑难消化特性来解释此现象,此外数学模型模拟分析发现潮汐的稀释作用也可以解释这种现象。但这两者都不能解释,在其他初级生产者稀少时,红树材输出的有机质可以被大量利用的现象。在有红树林的河口和近海岸水域生态系统中,藻类等非红树初级生产者具有比红树植物更高的初级生产力,而且更容易被动物获得和消化。可以认为是藻类等巨大初级生产力的竞争作用导致红树初级生产在消费者组织中很难被发现,如此上面提到的难题就能得到很好的解决。此外能量标签技术检测出的是红树的初级生产在消费者组织中的相对比率,不是绝对数量值,从此角度看,能量标签技术的结果与传统观点不是矛盾而是互相补充的关系。由此推测红树的初级生产应该还是被消费者所利用,只是它们在消费者初级营养来源组成中占的比例并不大,但其绝对数量并不少。这与传统观点认为的红树的初级生产被大量利用,支撑了具有巨大的次级生产稍有不同。此外,能量标签技术在红树林生态系统中的适用性尚未检验;计算食物组成的数学工具不是很完善;实验设计上考虑的不够全面;对定量研究有一定的影响。     

The Suitability of P. falciparum Merozoite Surface Proteins 1 and 2 as Genetic Markers for In Vivo Drug Trials in Yemen

Background

The accuracy of the conclusions from in vivo efficacy anti-malarial drug trials depends on distinguishing between recrudescences and re-infections which is accomplished by genotyping genes coding P. falciparum merozoite surface 1 (MSP1) and MSP2. However, the reliability of the PCR analysis depends on the genetic markers’ allelic diversity and variant frequency. In this study the genetic diversity of the genes coding for MSP1 and MSP2 was obtained for P. falciparum parasites circulating in Yemen.

Methods

Blood samples were collected from 511 patients with fever and screened for malaria parasites using Giemsa-stained blood films. A total 74 samples were infected with P. falciparum, and the genetic diversity was assessed by nested PCR targeting Pfmsp1 (Block2) and Pfmsp2 (block 3).

Results

Overall, 58%, 28% and 54% of the isolates harboured parasites of the Pfmsp1 K1, MAD20 and RO33 allelic families, and 55% and 89% harboured those of the Pfmsp2 FC27 and 3D7 allelic families, respectively. For both genetic makers, the multiplicity of the infection (MOI) was significantly higher in the isolates from the foothills/coastland areas as compared to those from the highland (P<0.05). Pfmsp2 had higher number of distinct allelic variants than Pfmsp1 (20 vs 11). The expected heterozygosity (HE) for Pfmsp1 and Pfmsp2 were 0.82 and 0.94, respectively. Nonetheless, a bias in the frequency distribution of the Pfmsp1 allelic variants was noted from all areas, and of those of Pfmsp2 in the samples collected from the highland areas.

Conclusions

Significant differences in the complexity and allelic diversity of Pfmsp1 and Pfmsp2 genes between areas probably reflect differences in the intensity of malaria transmission. The biased distribution of allelic variants suggests that in Yemen Pfmsp1 should not be used for PCR correction of in vivo clinical trials outcomes, and that caution should be exercised when employing Pfmsp2.     

Corticofugal regulation of auditory sensitivity in the bat inferior colliculus

Under free-field stimulation conditions, corticofugal regulation of auditory sensitivity of neurons in the central nucleus of the inferior colliculus of the big brown bat, Eptesicus fuscus, was studied by blocking activities of auditory cortical neurons with Lidocaine or by electrical stimulation in auditory cortical neuron recording sites. The corticocollicular pathway regulated the number of impulses, the auditory spatial response areas and the frequency-tuning curves of inferior colliculus neurons through facilitation or inhibition. Corticofugal regulation was most effective at low sound intensity and was dependent upon the time interval between acoustic and electrical stimuli. At optimal interstimulus intervals, inferior colliculus neurons had the smallest number of impulses and the longest response latency during corticofugal inhibition. The opposite effects were observed during corticofugal facilitation. Corticofugal inhibitory latency was longer than corticofugal facilitatory latency. Iontophoretic application of γ-aminobutyric acid and bicuculline to inferior colliculus recording sites produced effects similar to what were observed during corticofugal inhibition and facilitation. We suggest that corticofugal regulation of central auditory sensitivity can provide an animal with a mechanism to regulate acoustic signal processing in the ascending auditory pathway. Accepted: 15 July 1998     

Competition between Adjacent Meiotic Recombination Hotspots in the Yeast Saccharomyces Cerevisiae

In a wild-type strain of Saccharomyces cerevisiae, a hotspot for meiotic recombination is located upstream of the HIS4 gene. An insertion of a 49-bp telomeric sequence into the coding region of HIS4 strongly stimulates meiotic recombination and the local formation of meiosis-specific double-strand DNA breaks (DSBs). When strains are constructed in which both hotspots are heterozygous, hotspot activity is substantially less when the hotspots are on the same chromosome than when they are on opposite chromosomes.     

A novel piezoelectric quartz micro-array immunosensor based on self-assembled monolayer for determination of human chorionic gonadotropin

A novel multi-channel 2 x 5 model of piezoelectric quartz micro-array immunosensor has been developed for quantitative detection of human chorionic gonadotropin (hCG) in serum or urine samples. Every crystal unit of the fabricated piezoelectric hCG micro-array immunosensor can oscillate independently without interfering each other. A 2 x 5 model of micro-array immunosensor as compared with a one-channel immunosensor can provide eight times higher detection speeds for hCG assay. The anti-hCG antibody is deposited on the gold electrode's surface of 10 MHz quartz AT-cut crystal by self-assembled technique using sulfosuccinimidyl 6-[3'-(2-pyridyldithio) propionamido] hexanoate (Sulfo-LC-SPDP), and serves as an antibody recognizing layer. The highly ordered self-assembled monolayers (SAM) ensure well-controlled surface structure and offer many advantages to the performance of the sensor. Compared with conventional antibody immobilization methods, the amount and the reaction activity of antibody monolayer coated by the SAM binding are bigger than those by the SPA method, and less non-specific binding caused by other analytes in sample is found. Under the optimized experimental conditions, the results showed that micro-array immunosensor quantitatively detected serum or urine hCG in the range of 2.5-500 mIU/ml with high precision (CV<5%); other hormones in human serum and urine did not interfere with the determination markedly. Serum and urine samples of 60 patients were detected by the micro-array immunosensor, and the results agreed well with those given by the commercial radioimmunoassay test kit, with correlation coefficient of 0.92. After regeneration with urea solution the coated immunosensor can be reused five times without appreciable loss of activity.