黄鳝生殖干细胞在性逆转生殖发育过程中的变化

应用组织学方法及免疫组织化学技术显示,黄鳝性逆转生殖发育过程中,生殖干细胞(GSCs)定位分布于生殖褶中,黄鳝雌性发育阶段的GSCs分散或成团存在,间性及雄性发育阶段GSCs均区分为A、B两种不同类型,雌性发育阶段GSCs与A、B两类GSCs在超微结构上存在差异。结果表明,生殖褶中GSCs是黄鳝分化生殖腺中唯一具有有丝分裂能力的生殖细胞群,雌性发育阶段GSCs表现出卵原干细胞特征,间性及雄性发育阶段GSCs为精原干细胞。CD49整合素是黄鳝雌性发育阶段GSCs和A类GSCs的表征分子。     

大鼠坐骨神经结扎后脊髓钙结合蛋白PV的表达变化

目的:研究大鼠坐骨神经结扎模型钙结合蛋白Parvalbumin(PV)在脊髓的时空变化规律,为探讨其在神经再生中的作用与机制提供实验依据。方法:SD大鼠随机分为假手术对照组和坐骨神经结扎组,实验组结扎后分别存活1,3,7,14或21d,采用免疫组化结合图像分析技术观察PV在脊髓的表达变化。结果:在对照组,PV免疫阳性神经元主要分布于腰髓背角Ⅱ层,Ⅲ～Ⅵ层只观察到少量散在分布的PV样阳性神经元,脊髓前角Ⅷ层和Ⅸ层内也可见少量多极的大型阳性神经元。术后各时间点PV样阳性神经元表达下降,14d下降最显著,21d表达有所上升,但还是低于7d组。脊髓后角PV免疫阳性产物灰度值测定结果显示:术后14d后角PV表达最低,与对侧和对照组以及1、3d组相比有统计学意义(P<0.05)。结论:坐骨神经结扎后PV表达变化呈现一定的时空模式,为进一步揭示PV在神经系统疾病中的作用提供实验依据。     

Relations between carbon dioxide fluxes and environmental factors of Kobresia humilis meadows and Potentilla fruticosa meadows

Carbon dioxide fluxes of Kobresia humilis and Potentillafruticosa shrub meadows,two typical ecosystems in the Qinghai-Tibet Plateau,were measured by eddy covariance technology and the data collected in August 2003 were employed to analyze the relations between carbon dioxide fluxes and environmental factors of the ecosystems.August is the time when the two ecosystems reach their peak leaf area indexes and stay stable,and also the period when the net carbon absorptions of Kobresia humilis and Potentilla photo flux densities (PPFD),the carbon dioxide-uptake rate of the Kobresia humilis meadow is higher than that of the Potentilla fruticosa shrub meadow;where the PPFD are rates of the two ecosystems declined as air temperature increased,but the carbon dioxide uptake rate of the Kobresia humilis meadow decreased more quickly (-0.086) than that of the Potentilla fruticosa shrub meadow (-0.016).Soil moistures exert influence on the soil respirations and this varies with the vegetation type.The daily carbon dioxide absorptions of the ecosystems increase with increased diurnal temperature differences and higher diurnal temperature differences result in higher carbon dioxide exchanges.There exists a negative correlation between the vegetation albedos and the carbon dioxide fluxes.     

The formation of improved tetraploid population of red crucian carp × common carp hybrids by androgenesis

Bisexual fertile diploid androgenetic individuals (A0) (2n=100) were formed by androgenesis. In this way, the diploid spermatozoa from male allotetraploid hybrids (AT) (4n=200) of red crucian carp (Carassius auratus red var.) (♀) × common carp (Cyprinus carpio L.) (♂) were used to fertilize the UV-treated hap- loid eggs of goldfish (Carassius auratus), and living androgenetic diploid fish were developed. The A0 became sexually mature at the age of 2 years, and they fertilized with each other to form their offspring (A1). In this study, we observed the chromosomal number, gonadal structure and appearance of A1 fish. The results are as follows: (1) In A1, there were 85% tetraploids (A1-4n), 10% triploids (A1-3n) and 5% diploids (A1-2n), suggesting that diploid A0 could produce diploid gametes. It was concluded that the formation of diploid gametes generated from diploid A0 was probably related to the mechanism of pre-meiotic endoreduplication. (2) Among A1, only A1-4n possessed normal ovaries and testes. The mature males of A1-4n produced white semen. Under the electron microscope, the head of diploid sperm generated by A1-4n was bigger than that of haploid sperm generated by red crucian carp. In the testes of the A1-4n, there were many mature normal spermatozoa with a head bearing plasma mem- brane and a tail having the typical structure of "9 2" microtubules. Between the head and the tail, there were some mitochondria. The ovaries of A1-4n developed well and mainly contained II, III and IV-stage oocytes. The IV-stage oocytes were surrounded by inner and outer follicular cells. The micropyle was observed on the oolemma of follicular cells. There were abundant yolks and plenty of endoplasmic reticulum in the cytoplasm of IV-stage oocytes. Because A1-2n and A1-3n were distant crossing diploid hybrids and triploid hybrids respectively, they possessed abnormal gonads, and no mature semen and eggs were observed. (3) Compared with allotetraploids, the A1-4n fish not only had advantages such as fast growth rate and strong resistibility but also showed some new good performances such as high ratio of body width to body length, smaller heads and shorter tails. These results indicated that an- drogenesis could produce bisexual fertile tetraploids and improve the shape of allotetraploid hybrids as well, which will be of great significance in both the cell genetics research and fish breeding.     

Polymorphism attribution of cSNPs in cancer-related genes located in loss regions with a high frequency of HCC between HBV and health groups

Cancer-related genes harbored in the loss regions containing a high frequency of hepatocellular carcinoma (HCC) were selected.Related information was gathered and the coding single nucleotide polymorphism (cSNP) sequences were obtained from the single nucleotide polymorphism (SNP) database.The appropriate primers and oligonucleotide probes were then designed in accordance with the SNP sites,and subsequently,the gene chips for detecting SNPs were constructed.Genomic DNA was extracted from blood samples of healthy controls and from patients with HBV infection.The sequences,including the SNPs,were amplified via polymerase chain reaction (PCR) and labeled using digoxigenin deoxyuridine tri-phosphate (Dig-dUTP).The labeled products were then hybridized with the SNP chips.Results confirmed that the differences in allele frequencies of three SNPs EGFL3 (rs947345),Caspase9 (rs2308950),and E2F2 (rs3218171) were distinct between HBV-infected patients and controls,suggesting that these SNPs ocuring in high frequency in HBV-infected individuals may be associated with susceptibility to HCC.     

A cancer protein microarray platform using antibody fragments and its clinical applications

Antibody microarrays have shown great potential for measurement of either a spectrum of target proteins in proteomics or disease-associated antigens in molecular diagnostics. Despite its importance, the applications of antibody microarrays are still limited by a variety of fundamental problems. Among them, cross-reactivity significantly limits the multiplexing ability in parallel sandwich immunoassays. As a result, it is very important to design new capture probes in order to incorporate a universal label into the assay configuration. In this report, an antibody fragments (F(ab')2) microarray platform for serum tumor markers was developed. Each antigen was detected at different concentrations to assemble its calibration curve, and combinations of different markers were tested to examine the specificity of simultaneous detection based on the F(ab')2 microarrays. Diagnostics of serum samples with this cancer antibody microarray platform and immunoradiometric assays (IRMA) were also performed. Wide range calibration curves (0-1280 U mL(-1)) were obtained for each tumor marker. Comparative studies demonstrated that such F(ab')2 microarrays exhibited both moderately improved sensitivity and better specificity than full-sized monoclonal antibody microarrays. It is also demonstrated that this microarray platform is quantitative, highly specific and reasonably sensitive. More importantly, clinical applications of our F(ab')2 microarray platform for upwards of 100 patient serum samples clearly show its potential in cancer diagnostics.     

Determination of triazines in infant nutrient cereal-based foods by pressurized microwave-assisted extraction coupled with high-performance liquid chromatography-mass spectrometry

A method for determining triazine herbicides in infant nutrient cereal-based foods by pressurized microwave-assisted extraction (PMAE), coupled with high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI/MS), is described. The key parameters of PMAE, including extraction solvent, extraction time and temperature, were optimized. The isolation of the target compounds from the matrix was found to be efficient when 2 g of nutrient cereal samples was extracted with 20 mL of methanol for 10 min at 105 degrees C. Final determination was accomplished by HPLC-ESI/MS. The recoveries from 66.2 to 88.6% were obtained for three compounds at fortification levels (5-500 microg kg(-1)) with relative standard deviations (R.S.D.) 相似文献   

The Role of Phe181 in the Hexamerization of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Quinolinate Phosphoribosyltransferase

Quinolinic acid phosphoribosyltransferase (QAPRTase; NadC) catalyzes an indispensable step in NAD biosynthesis, one that is essential for cell survival in prokaryotes, which makes it an attractive target for antibacterial drug therapy. We recently reported the crystal structures of Helicobacter pylori QAPRTase with bound quinolinic acid, nicotinamide mononucleotide, and phthalic acid. The enzyme exists as a hexamer organized as a trimer of dimers, which is essential for full enzymatic activity. The loop between helix α7 and strand β8 contributes significantly to the hydrophobic dimer-dimer interactions. Phe181Pro mutation within the α7-β8 loop disrupts the hexamerization of QAPRTase, and the resultant dimer shows dramatically reduced protein stability and no activity. Our findings thus suggest that compounds able to disrupt its proper oligomerization could potentially function as selective inhibitors of Helicobacter pylori QAPRTase and represent a novel set of antibacterial agents.     

A bioactive foam reactor for the removal of volatile organic compounds: system performance and model development

A bioactive foam reactor (BFR), a novel bioreactor operated using surfactant foams and suspended microorganisms for the treatment of gaseous toluene, was investigated to characterize its performance with respect to the mass transfer and biodegradation rates. The BFR system consisted of two reactors in series; a foam column for toluene mass transfer using fine bubbles and a cell reservoir where suspended microorganisms actively biodegraded toluene. In this study, a series of short-term experiments demonstrated that the BFR could achieve stable removal performance and a high elimination capacity (EC) for toluene at 100.3 g/m³/h. A numerical model, combining mass balance equations for the mass transfer and subsequent biodegradation, resulted in reasonable agreement with the experimental findings. At an inlet toluene concentration of 100 ppm_v, the toluene concentration in the liquid phase remained extremely low, indicating that the microbial activity was not hindered in the BFR system. However, the experimental and model prediction results showed that the actual mass of toluene transferred into the liquid phase was not closely balanced with the amount of toluene biodegraded in the BFR used in this study. Consequently, methods, such as increasing the effective volume of the foam column or the mass transfer coefficient, need to be implemented to achieve higher toluene EC and better BFR performance.