Prenatal diagnosis of ornithine transcarbamylase deficiency: Results in SPFASH mice

Ornithine transcarbamylase (OTC) deficiency is a human X-chromosome-linked disease (McKusick 31125). The presence of OTC activity in the human placenta encouraged us to examine the possible diagnosis of the disease in an animal model (Spf^ash mice) by enzymatic assay on placental samples. A significant positive correlation (P< 0·02) was found between placental and hepatic activities; the pH dependence of OTC was similar in the placenta and liver when compared within normal or homozygous mutant mice. The apparent K_m (ornithine) and K_m (carbamoylphosphate) values of the enzyme did not show any significant differences when compared in both placentae and livers of normal fetuses. The use of OTC assay in the placenta for prenatal diagnosis of OTC deficiency in mouse fetuses obtained by the crossbreeding of Spf^ash/+ with +/Y has shown that our method has good diagnostic value. We made the diagnosis of OTC deficiency in male fetuses with a sensitivity and a specificity of 1·0. The + gene from the father in Spf^ash/ + animals is preferentially inactivated in extraembryonic tissues, explaining why very low placental OTC activity was observed in 12 of the 18 female fetuses studied. Because these 12 females have variable OTC activity in their livers, it is not possible to appreciate the true residual activity in their livers by measuring this activity in the placenta.     

Prenatal diagnosis of congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency by steroid analysis in the amniotic fluid of mid-pregnancy: Comparison with HLA typing in 17 pregnancies at risk for CAH

Amniotic fluid (AF) levels of 17-hydroxyprogesterone (17OHP) and testosterone (T) were determined at 16–17 weeks in 17 pregnancies at risk for CAH and results compared to 75 normal controls. The fetus was predicted to be unaffected in 12 cases on the findings of normal AF levels of both 17OHP and T and the latter allowed a correct prediction of fetal sex in all instances. HLA typing confirmed normality in 12 cases revealing 5 carriers, 5 homozygous normal and 2 indeterminate. Steroid levels of the 2 groups were similar. Three fetuses were predicted to be CAH affected on unambiguously high levels of 17OHP and T (in female only). HLA typing was in agreement, and the diagnosis was confirmed in 2 abortuses and a female newborn by physical and hormonal studies. In the last 2 cases AF levels of OHP and T were normal but HLA (A/B/C) genotypes were identical to the CAH affected siblings. Normal physical and hormonal findings in the 2 aborted fetuses would exclude the possibility of an in utero virilizing form of CAH. The discrepancy could be explained on the basis that the fetuses had an allelic form of 21-hydroxylase deficiency or on the basis of recombination (not fully tested). It is concluded that a fully informative prenatal diagnosis of CAH should not rely entirely on HLA typing but on hormonal studies.     

Microbial activity related to N cycling in the rhizosphere of maize stressed by heavy metals

A greenhouse experiment was carried out to compare differences in potential activities of ammonification, nitrification and denitrification in rhizosphere and bulk soil in a heavy-metal-stressed system. Exchangeable fractions of Cd, Cu and Cr were all higher in the rhizosphere of maize than in bulk soil. Results showed that the mineralization of N in soil was stimulated by low concentration of Cd.Addition of Cd at low levels stimulated the ammonifying and nitrifying activity in soil, while inhibitory influences were shown at high levels.Nitrifying bacteria was proved to be the most sensitive one, whilst the effect on denitrifying bacteria was very limited. Comparing Cd, Cu and Cr(Ⅵ) at 20 mg/kg soil, Cd was the most effective inhibitor of ammonification and denitrification, while Cr(Ⅵ) had the strongest influence on nitrifying activity. Root exudates played important roles on the different exchangeable metal fractions and bacterial activities between rhizosphere and non-rhizosphere. Nitrate was the main form of mineral N in soil, as well as the main form of N absorbed by plants, but the formation and relative absorption of ammonium were promoted in response to high Cd exposure.     

Detection of both the normal and mutant alleles in single cells of individuals heterozygous for the sickle cell mutation—prelude to preimplantation diagnosis

As a preliminary step to preimplantation diagnosis of sickle cell disease in unfertilized eggs or 8-cell embryos of heterozygous parents, we established quality control for detection of the mutant and normal alleles of the beta-haemoglobin gene using single buccal cells. Efficient polymerase chain reaction (PCR) amplification of a 680 base pair sequence of the beta-globin gene spanning the site of the sickle cell mutation was obtained for 79 per cent of single heterozygous cells. In 71 per cent of cases, both alleles were detected. With this current efficiency, we predict that a clinical preimplantation diagnosis at the 8-cell embryo stage could be carried out safely and reliably for a couple at risk of transmitting sickle cell disease to their children.     

Uncertainties related to the identification of the marginal energy technology in consequential life cycle assessments

When performing life cycle assessment (LCA) assumptions regarding the energy use are often decisive for the outcome. In this paper, current approaches of identifying marginal electricity and heat technologies for consequential LCAs are challenged. The identification of marginal energy technologies is examined from three angles: The marginal electricity technology is identified in Danish historical and potential future energy systems. The methods of identifying and using marginal electricity and heat technologies in key LCA studies are analysed. Finally, the differences in applying energy system analysis and assuming one marginal technology are illustrated, using waste incineration with energy substitution as a case. The main problem with the current approach is the use of one single marginal technology. It is recommended to use fundamentally different affected technologies and identify these in several possible and fundamentally different future scenarios. If possible, the affected technologies should also be identified based on energy system analyses considering the technical characteristics of the technologies involved. Some results in this paper may be applicable to other affected technologies than energy.     

PnET-CN模型对东亚森林生态系统碳通量模拟的适用性和不确定性分析

东亚地区森林类型多样,开展区域生态系统碳循环模拟时应考虑森林类型的差异。论文利用基于叶氮浓度-最大净光合作用速率关系的PnET-CN模型,对东亚地区8 个森林生态系统通量观测站点的总生态系统碳交换（GEE）和生态系统呼吸（RE）进行模拟,以探讨模型的适用性并对不确定性来源进行分析。研究结果表明：①PnET-CN模型能较为准确地模拟东亚地区大部分森林生态系统站点的GEE和RE;②模型的适用性排序依次为温带、寒温带、亚热带、 热带,模型未能很好地模拟热带湿地森林GEE和RE 的季节与年际变异;③在同一气候区中,PnET-CN模型更加适用于针叶林碳交换的模拟;④PnET-CN模型比较准确地反映了东亚森林生态系统GEE、RE对气候因子（例如,温度或辐射）的响应,但在低温、较弱辐射条件下模型低估了GEE,在高温或较强辐射条件下高估了GEE;在低温条件下模型低估了RE,在高温条件下模型高估了RE。针对东亚多个森林通量站点的模拟情况,论文提出模型应在以下方面进行改进：①PnET-CN模型计算物候时除了考虑温度之外还应加入土壤湿度的影响,并对不同气候区森林生态系统赋予不同叶片凋落时长;②PnET-CN模型中温度对GEE的限制以及光合最适温度应该根据不同站点设置;③PnET-CN模型应该考虑森林生态系统对环境胁迫的适应性,加强对干旱等干扰的模拟;④同时对于拥有复杂水文条件的森林生态系统应该改进土壤含水量的算法,以准确反映该类型森林生态系统GEE和RE的季节变化。     

南海表层海水参与卡尔文循环的固碳基因多样性研究

为揭示南海北部表层海水中参与卡尔文循环的固碳基因多样性及其与环境因子的关系,本研究以卡尔文循环中的关键酶核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubis CO)的Ⅰ、Ⅱ型基因(cbbL、cbbM)作为分子标记,采用Illumina Miseq高通量测序技术对海水中的固碳基因多样性进行分析,并结合多元统计分析的方法,探讨了固碳基因多样性与环境因子的关系.结果显示,在南海北部表层海水中,含cbbL基因固碳基因主要归属于变形菌门(Proteobacteria)、蓝藻门(Cyanobacteria)和厚壁菌门(Firmicutes),其中,优势亚群分别是γ-变形菌亚门(45.3%)、蓝细菌(30.9%)和β-变形杆菌亚门(23.8%);而含cbbM基因的固碳菌群未检测到;近岸的A9站位与其他站位物种组成有一定的差异,异着色菌属(Allochromatium)、硫杆菌属(Thiobacillus)和硫单胞菌属(Thiohalomonas)为其特有菌属.相关性和冗余分析(RDA)结果显示,含cbbL基因的固碳基因丰度与水温、盐度呈显著负相关(p0.01),与硝酸盐、亚硝酸盐、硅酸盐呈显著正相关(p0.01).     

石家庄地区近70年来伴随经济发展的水文环境变化分析

论文系统分析了石家庄地区70年来伴随社会经济发展的水资源开发历史,结合水文资料探讨了人类活动对区域水文环境变迁的影响。并通过对地下水采样,结合室内水化学和氚同位素测定,确认区域地下水补给来源主要是通过河道得到线状的垂向补给,和上游含水层的侧向补给两种天然途径。城市及工农业发展改变了区域水循环系统的补排结构。河流断流减少了地下水的垂向补给,造成地下水的补给源从原来的天然垂向补给和上游的侧向补给,变为单一的侧向补给。另一方面,大量开采地下水已成为区域地下水排泄的主要方式。其中用于农业灌溉的大部分以蒸发、蒸腾的形式耗散于大气,无法回补。地下水位的持续下降、地下水化学类型转变及其空间分布显示了水量和水质以及生态环境的变化。     

PM2.5暴露对小鼠肝脏能量代谢的影响

通过细颗粒物(particulate matter 2.5,PM_(2.5))的暴露,探讨其对小鼠肝脏能量代谢方式的影响及作用机制.采用透射电镜(TEM)观察肝脏组织中线粒体超微结构的改变,并检测了三磷酸腺苷(ATP)、丙酮酸和乳酸含量的变化,同时用实时荧光定量-聚合酶链式反应(RT-PCR)检测糖酵解相关基因果糖-2,6-二磷酸酶(PFKFB3)和乳酸脱氢酶(LDHB)及三羧酸循环(TCA)相关基因丙酮酸脱氢酶(PDHA1)、柠檬酸合成酶(CS)和延胡索酸酶(FH)的表达情况.此外,还对活性氧(ROS)的水平进行检测.结果表明,PM_(2.5)暴露对小鼠肝脏组织中的线粒体造成损伤,导致ATP的下降,丙酮酸和乳酸的积累.此外,PDHA1、CS和FH的表达明显降低,PFKFB3和LDHB的表达显著升高,这些结果共同表明PM_(2.5)改变了小鼠肝脏的能量代谢方式.同时ROS水平明显升高,表明PM_(2.5)暴露可能是通过ROS抑制三羧酸循环,增强糖酵解方式来为机体提供能量,从而对肝脏的能量代谢产生影响.     

模式采样法采集尾气中BaP的研究

用模式了取样法集汽车柴油发动机尾气中多环茎烃,并重点对ＢａＰ采样方法进行研究,结果表明,该法采样时间仅１－２ｓ,采样体积为３３０ｍｌ（ｓ．次）,回收率７７．６％,９次重复的变异系数为２９．６％,测得ＢａＰ的数据与国际ＩＳＯ规定的ＣＶＳ定容取样法可比。     

土壤酸化-植被生产力空间信息模型构建及贵州典型森林对酸沉降的生态效应响应

将遥感数据驱动的土壤水平衡模型、植被生产力光能利用率模型与基于过程的土壤酸化模型、营养元素循环模型相耦合,建立森林土壤酸化-植被生产力空间信息模型,定量表达土壤和土壤水离子浓度、植被生产力、营养元素循环空间分异.将模型模块化,耦合于自主开发的EcoHAT系统(Ecohydrolgy Assessment Tools),并以贵州典型森林群落为研究对象,运用模型对群落土壤化学性质、植被生产力和营养元素生物循环的关键过程的时空演变模式进行了模拟和研究,与实验数据进行验证,取得良好的效果.运用情景设定的方式,定量模拟研究区酸雨的强度变化导致土壤中植被可吸收的盐基离子变化,以及对森林植被净第一性生产力(NPP)的间接影响.