Novel mutations in the human CYP21 gene

The great majority of genetic defects underlying steroid 21-hydroxylase deficiency appear to result from intergenic recombinations between the homologous CYP21 and CYP21P genes. For a minority, novel sporadic point mutations have been detected. De novo mutations in CYP21 have also been reported, but only a few studies have systematically screened their occurrence. We here describe a population-based patient sample in order to estimate the rate of single-family (i.e. sporadic) and de novo germline mutations in the human CYP21 locus. Among 76 Finnish families were observed three single-family mutations and two de novo mutations in CYP21. The rates obtained, ∼5% and ∼2% for novel and de novo mutations, respectively, indicate that they are not rare and that their occurrence should not be ignored in genetic diagnostics of this disorder. Copyright © 2001 John Wiley & Sons, Ltd.     

Evaluation of a fetus at risk for dihydropteridine reductase deficiency by direct mutation analysis using denaturing gradient gel electrophoresis

Dihydropteridine reductase (DHPR) is an enzyme involved in the recycling of tetrahydrobiopterin (BH₄), which is an obligate co-factor of the aromatic amino acid hydroxylases. DHPR deficiency is a rare, autosomal recessive disorder caused by mutations in the QDPR gene. DHPR-deficient patients are diagnosed by a lack of response to a low phenylalanine diet and by severe neurological symptoms. Final diagnosis is made by measurements of neurotransmitters and pterin metabolites in cerebrospinal fluid (CSF) and urine, in addition to DHPR enzyme activity, which can be assessed in whole red blood cells. Treatment of DHPR deficiency can be difficult and the outcome is not always satisfying, even if all treatment strategies are followed. Therefore prenatal diagnosis is of great importance in affected families. Prenatal diagnosis is possible by measuring DHPR activity in different cell types but this is time consuming. More than 25 different mutations have to date been identified in the QDPR gene and direct identification of a mutation in a fetus would be easy and rapid. We have developed a method based on denaturing gradient gel electrophoresis (DGGE) for the analysis of the QDPR gene. The method is useful for rapid and simultaneous scanning of all exons and flanking intronic sequences of the QDPR gene. We describe the first prenatal diagnosis conducted using this method. Copyright © 2001 John Wiley & Sons, Ltd.     

Prenatal determination of uridine diphosphate galactose-4-epimerase activity

A prenatal diagnosis has been performed in a pregnancy at risk for uridine diphosphate galactose-4-epimerase deficiency, an enzyme variation causing severe symptoms in the neonatal period similar to those of classical galactosaemia. The postnatal enzyme investigation, and uneventful development of the child, indicate that the prediction of an unaffected, heterozygous, fetus was correct.     

氢化物发生原子荧光法测定地表水和饮用水中的痕量砷、汞、硒

文章研究了用SK-2002 AFS analyser氢化物发生原子荧光法测定地表水和饮用水中的砷、汞、硒的测定。在5％的酸度条件下加入5％硫脲＋5％抗坏血酸,20g／L的硼氢化钾为还原剂,调整仪器的空气和辅气流量及分析条件为文中条件,取水样中分别添加砷,汞,硒,使它们的浓度分别为2μg/L,0．4μg／L,4μg／L,连续测定12次,以砷,汞,硒的相对标准偏差分别为0．4％,1．1％,1．2％。取水样加入As,Hg,Se标准分别为2．0ng,0．6ng,4．0ng,测定的添加标准回收率分别为99．5％,97．5％,95．8％。研究结果表明,该方法操作简便,快速,灵敏,干扰少,检出限低等特点,适合于测定地表水和饮用水中砷,汞,硒的测定。     

富硒藻类研究进展

微量元素硒不仅是人和动物必需的营养元素,也是植物生长发育不可缺少的元素。硒酸盐在水体中溶解度高于其他环境介质,导致水生生物对无机硒(硒酸盐)有更高的利用率。藻类能吸收无机硒,可将无机硒有效地转化为有机形态。藻体内的硒主要以硒蛋白、硒核酸、硒多糖等生物大分子以及硒代半胱氨酸和硒代蛋氨酸等生物小分子有机化合物存在。在水生生态系统中,藻类是硒的主要吸收者。富硒藻类通过食物链将硒传递至浮游动物、贝和鱼等动物体内,能提高其抗氧化能力,从而导致其对重金属耐受性增强。本文综述了藻类在自然界硒生物有机化中的地位和作用,藻类对硒的富集方式及代谢途径,硒在藻类中的生物学效应,富硒藻类的开发利用现状及今后的发展方向,较全面地综述了富硒藻类研究进展。     

Developmental stress affects song learning but not song complexity and vocal amplitude in zebra finches

Several recent studies have tested the hypothesis that song quality in adult birds may reflect early developmental conditions, specifically nutritional stress during the nestling period. Whilst all of these earlier studies found apparent links between early nutritional stress and song quality, their results disagree as to which aspects of song learning or production were affected. In this study, we attempted to reconcile these apparently inconsistent results. Our study also provides the first assessment of song amplitude in relation to early developmental stress and as a potential cue to male quality. We used an experimental manipulation in which the seeds on which the birds were reared were mixed with husks, making them more difficult for the parents to obtain. Compared with controls, such chicks were lighter at fledging; they were thereafter placed on a normal diet and had caught up by 100 days. We show that nutritional stress during the first 30 days of life reduced the birds’ accuracy of song syntax learning, resulting in poorer copies of tutor songs. Our experimental manipulations did not lead to significant changes in song amplitude, song duration or repertoire size. Thus, individual differences observed in song performance features probably reflect differences in current condition or motivation rather than past condition.     

土壤硒的生物有效性研究

对黑麦幼苗的试验表明,黑麦幼苗中的总硒(Se)浓度与总干重的乘积与0.1mol/L KH2PO4浸提态Se呈显著相关.对黑油菜的试验表明,在酸性土壤上,当Se(Ⅵ)的量≥0.5mg/kg时,可显著减少黑油菜的产量;而当Se(Ⅳ)的量达到2.0mg/kg时对产量影响不大;黑油菜吸收Se(Ⅵ)的量要大于吸收Se(Ⅳ)的量.通过田间采样分析表明,KH2PO4浸提态Se能反映土壤对植物的供Se状况,推荐用0.1mol/L KH2PO4溶液作为酸性土壤生物有效性Se的浸提溶液.影响土壤Se生物有效性的主要因子是CaCO3,其次是粉粒、有机质、黏粒含量.pH值可通过CaCO3对KH2PO4浸提态Se产生影响.     

广州及周边地区森林土壤As、Se、Hg质量分数特征及污染评价

研究了广州及周边地区5处代表性森林土壤（鼎湖山、西樵山、华南植物园、黄埔和南昆山）As、Se、Hg质量分数特征及污染状况。结果表明,上述5地森林表层土壤As质量分数平均值分别为18.6、18.0、12.2、11.4、26.1 mg.kg-1,Se质量分数平均值分别为0.360、0.729、0.286、0.421、0.434 mg.kg-1,Hg质量分数平均值分别为0.201、0.270、0.139、0.224、0.087 mg.kg-1。除植物园土壤Se质量分数、南昆山土壤Hg质量分数较接近背景值外,5林地As、Se、Hg质量分数均超过背景值,可能存在外源As、Se、Hg输入。其中,南昆山As输入,西樵山Se、Hg输入,黄埔、鼎湖山Hg输入较明显。单因子污染指数分析结果表明在南昆山As为最严重的污染物,而在鼎湖山、植物园、西樵山和黄埔Hg为最严重的污染物。综合污染指数分析结果表明5林地土壤均受到不同程度的污染,其中西樵山土壤属重度污染,南昆山、黄埔、鼎湖山属中度污染,植物园污染较轻,属轻度污染。     

Effects of selected metal oxides on the dechlorination and destruction of PCDD and PCDF

OCDD and OCDF spiked silica/graphite based model fly ash containing various copper compounds and metal oxides were thermally treated under oxygen deficient conditions. All copper compounds tested showed a considerable dechlorination/hydrogenation reaction at 260 °C. After 30 min at 340 °C, less than 1% of the spiked OCDD and OCDF was recovered as T₄CDD/F to OCDD/F. Other compounds tested demonstrated a lower rate of dechlorination compared to the copper compounds. However, all other metal oxides showed a small dechlorination effect at 260 °C, which was considerably increased at 340 °C.

The model fly ash containing the different copper compounds or metal oxides showed comparable PCDD and PCDF isomer patterns after thermal treatment. However, small differences were observed among the different tested compounds. The PCDD and PCDF isomer patterns on the model fly ashes were similar to patterns found during dechlorination experiments on fly ashes from waste incineration processes.

Model fly ash containing Ca(OH)₂ exhibited the highest destruction potential, but a low dechlorination potential. In contrast, model fly ash containing any of the remaining compounds tested, was found to predominantly dechlorinate the spiked OCDD and OCDF.     

Prenatal diagnosis of carnitine palmitoyltransferase 2 deficiency in chorionic villi: a novel approach

Carnitine palmitoyltransferase 2 (CPT2) deficiency, the most common autosomal recessive inherited disease of the mitochondrial long-chain fatty acid (LCFA) β-oxidation, may result in three distinct clinical phenotypes, namely, a mild adult muscular form, a severe infantile hepatocardiomuscular disease, and a neonatal form, which includes dysmorphic features in addition to hepatocardiomuscular symptoms. Both the latter forms are life-threatening diseases, and prenatal diagnosis (PND) can be offered to couples at a one-fourth risk of having an affected child. PND of CPT2 deficiency hitherto relied mostly on mutation detection from fresh chorionic villi (10 weeks' gestation), since CPT2 activity could be assayed on cultured amniocytes only (16–17 weeks' gestation). We devised a CPT2 activity assay from 10 mg of chorionic villi sampling (CVS). Combining this enzymatic assay to haplotype study using polymorphic markers linked to the CPT2 gene, we were able to carry out within 2 days, CPT2 deficiency PND, in two unrelated families, using a CVS performed at the 11th week of gestation. Copyright © 2003 John Wiley & Sons, Ltd.