What Do We Really Know about Cellulose Biosynthesis in Higher Plants?

Cellulose biosynthesis is one of the most important biochemical processes in plant biology. Despite the considerable progress made during the last decade, numerous fundamental questions related to this key process in plant development are outstanding. Numerous models have been proposed through the years to explain the detailed molecular events of cellulose biosynthesis. Almost all models integrate solid experimental data with hypotheses on several of the steps involved in the process. Speculative models are...     

Sysmex CA-1500全自动血凝分析仪混匀马达替换后性能评价

目的评价用手机震动器替换Sysmex CA-1500全自动血凝分析仪混匀马达后的性能。方法测定混匀马达被替换后Sysmex CA-1500全自动血凝分析仪的PT、APTT、FIB三个项目,并与用Sysmex CA-500全自动血凝分析仪测定结果比对。结果PT、APTT、FIB三个项目测定的准确性、精密度及线性情况良好,结果可靠。且与Sysmex CA-500全自动血凝分析仪比对结果一致。结论用手机震动器替换血凝分析仪混匀马达,符合使用要求,延长仪器使用寿命。     

床边CR的影像质量分析与临床应用

目的通过对床边CR摄影之胸片影像质量的分析,以便提供高质量影像图像服务于临床。方法对2008年6月-12月所有的床边CR胸片230份进行分析总结。结果CR胸片中符合或达到诊断要求的213份,占92.6%,余7.3%经过重摄后均达诊断要求。结合临床,床边CR的应用对胸部疾病的初步诊断的准确性较高约达80.1%。结论床边胸片影像质量可以符合使用要求,值得推广。     

微量元素的检测及实际意义

介绍二种微量元素分析仪检测原理,以及用于对1785位儿童检测分析的结果。并阐述微量元素的缺乏或过多的危害性,希望引起社会及广大家长的高度重视。     

Arsenic trioxide promotes mitochondrial DNA mutation and cell apoptosis in primary APL cells and NB4 cell lines

This study aimed to investigate the effects of arsenic trioxide(As2O3) on the mitochondrial DNA(mtDNA) of acute promyelocytic leukemia(APL) cells.The NB4 cell line was treated with 2.0 μmol/L As2O3 in vitro,and the primary APL cells were treated with 2.0 μmol/L As2O3 in vitro and 0.16 mg kg-1 d-1 As2O3 in vivo.The mitochondrial DNA of all the cells above was amplified by PCR,directly sequenced and analyzed by Sequence Navigatore and Factura software.The apoptosis rates were assayed by flow cytometry.Mitochondrial DNA mutation in the D-loop region was found in NB4 and APL cells before As2O3 use,but the mutation spots were remarkably increased after As2O3 treatment,which was positively correlated to the rates of cellular apoptosis,the correlation coefficient:rNB4-As2O3=0.973818,and rAPL-As2O3=0.934703.The mutation types include transition,transversion,codon insertion or deletion,and the mutation spots in all samples were not constant and regular.It is revealed that As2O3 aggravates mtDNA mutation in the D-loop region of acute promyelocytic leukemia cells both in vitro and in vivo.Mitochondrial DNA might be one of the targets of As2O3 in APL treatment.     

Admixture Mapping of Obesity‐related Traits in African Americans: The Atherosclerosis Risk in Communities (ARIC) Study

Obesity is an important cause of morbidity and mortality worldwide. In the United States, the prevalence of obesity is higher in African Americans than whites, even after adjustment for socioeconomic status (SES). This leads to the hypothesis that differences in genetic background may contribute to racial/ethnic differences in obesity‐related traits. We tested this hypothesis by conducting a genome‐wide admixture mapping scan using 1,350 ancestry‐informative single‐nucleotide polymorphisms (SNPs) in 3,531 self‐identified blacks from the Atherosclerosis Risk in Communities (ARIC) study. We used these markers to estimate the overall proportions of European ancestry (PEAs) for each individual and then scanned for the association between PEA and obesity‐related traits (both continuous and dichotomous) at each locus. The median (interquartile range) PEA was 0.151 (0.115). PEA was inversely correlated with continuous BMI, weight, and subscapular skinfold thickness, even after adjusting for socioeconomic factors. In contrast, PEA was positively correlated with BMI‐adjusted waist circumference. Using admixture mapping on dichotomized traits, we identified a locus on 2p23.3 to be suggestively associated with BMI (locus‐specific lod = 4.11) and weight (locus‐specific lod = 4.07). After adjusting for global PEA, each additional copy of a European ancestral allele at the 2p23.3 peak was associated with a BMI decrease of ～0.92 kg/m² (P = 2.9 × 10^?5). Further mapping in this region on chromosome 2 may be able to uncover causative variants underlying obesity, which may offer insights into the control of energy homeostasis.     

Regulation of CCR5 Expression in Human Placenta: Insights from a Study of Mother-to-Child Transmission of HIV in Malawi

Background

Human promoter polymorphisms in the chemokine co-receptor 5 gene (CCR5) have been noted for association with mother-to-child transmission of HIV (HIV MTCT) as well as reduced receptor expression in vitro, but have not been clearly associated with CCR5 expression in vivo. Placental expression of CCR5 may be influenced by such polymorphisms as well as other in vivo regulatory factors.

Methodology/Principal Findings

We evaluated the associations between infant CCR5 polymorphisms, measures of maternal infection, and placental expression of CCR5 among mother-infant pairs in Blantyre, Malawi. RNA was extracted from placental tissue and used in multiplex real-time PCR to quantify gene expression. Through linear regression, we observed that CCR5-2554T (β = −0.67, 95% CI = −1.23, −0.11) and -2132T (β = −0.75, 95% CI = −0.131, −0.18) were significantly associated with reduced placental expression of CCR5. An incremental increase in CCR5 expression was observed for incremental increases in expression of two heparan sulfate genes involved in viral infection, HS3ST3A1 (β = 0.27, 95% CI = 0.18, 0.35) and HS3ST3B1 (β = 0.11, 95% CI = 0.06, 0.18). Among HIV infected mothers, an incremental increase in maternal HIV viral load was also associated with higher CCR5 expression (β = 0.76, 95% CI = 0.12, 1.39). Maternal HIV status had no overall effect (β = 0.072, 95% CI = −0.57, −0.72). Higher CCR5 expression was observed for mothers with malaria but was not statistically significant (β = 0.37, 95% CI = −0.43, 1.18).

Conclusions/Significance

These results provide in vivo evidence for genetic and environmental factors involved in the regulation of CCR5 expression in the placenta. Our findings also suggest that the measurement of placental expression of CCR5 alone is not an adequate indicator of the risk of mother-to-child transmission of HIV.     

Urinary biomarkers for monitoring disease progression in the Han:SPRD-cy rat model of autosomal-dominant polycystic kidney disease

The Han:SRPD-cy rat is a well-recognized model of human autosomal-dominant polycystic kidney disease. The disease is characterized by the development of progressive renal cysts, leading to declining renal function. Disease progression typically is monitored by measurement of plasma urea concentration. Although plasma urea may be an adequate measure of overall renal function, urinary biomarkers capable of accurately monitoring disease progression may be equally useful. The goal of this study was to assess several urinary biomarkers as potential markers of disease progression in male and female Han:SPRD-cy rats. These biomarkers were compared with changes in plasma urea concentration and morphometric changes as the disease progressed. Urinary activity of N-acetyl-β-D-glucosaminidase and concentration of α-glutathione S-transferase were measured as markers of proximal tubular dysfunction, glutathione S-transferase Yb1 as a distal tubular marker, and collagen IV as a biomarker for glomerular lesions. Urinary albumin was used as biomarker of glomerular or proximal tubular lesions. Albuminuria increased in male rats as the disease progressed, correlating with increasing plasma urea and morphologic changes. Urine concentrations of α-glutathione S-transferase decreased significantly in the male heterozygotic compared with wildtype rats in the later stages of the disease. Urinary concentrations of glutathione S-transferase Yb1 and collagen IV and activity of N-acetyl-β-D-glucosaminidase did not change during disease progression. Measurement of urinary albumin and concentrations of α-glutathione S-transferase may be useful for monitoring disease progression in the male Han:SPRD-cy rat model in future experiments.     

Root contraction helps protect the "living rock" cactus Ariocarpus fissuratus from lethal high temperatures when growing in rocky soil

? Premise of the study: We investigated how the "living rock" cactus Ariocarpus fissuratus, like other low-growing desert plants, can endure potentially lethal high temperatures at the soil surface. Specifically, we examined how shoot descent by root contraction in the presence or absence of soil rocks influences shoot temperatures and transpiration. ? Methods: Root contraction was identified by measuring shoot descent and anatomical analysis. Temperatures and transpiration were measured for plants at two heights in sandy and rocky soil, and temperature tolerances were determined by vital staining. ? Key results: Plants embedded in rocky soil survived an extreme heat episode, unlike plants in sandy soil, though rocks did not moderate low temperatures. Root contraction occurred regardless of season and soil moisture. Xylem conduits (wide-band tracheids) formed a compressible lattice that decreased root length as rays enlarged the root base radially. Plant position in the soil did not affect transpiration. ? Conclusions: Contractile roots pulled plants of A. fissuratus into the soil at rates of 6-30 mm yr(-1). Maintaining shoots level with the soil surface kept plant temperatures below the high lethal temperature and improved survivorship in soil shaded by surface rocks.