First trimester diagnosis of β-thalassaemia in a twin pregnancy

This paper reports the results of first trimester prenatal diagnosis in a twin pregnancy at risk for homozygous β°−thalassaemia (β°−39 mutant). Trophoblast samples from both twins were obtained at 10 weeks gestation with a forceps guided by ultrasound. Trophoblast DNA analysis, carried out with the oligonucleotide technique, revealed that one fetus was homozygous and the other heterozygous for the β−39 mutant. This diagnosis was confirmed at 17 weeks gestation by amniocyte DNA analysis. DNA polymorphism analysis within the α-globin gene provided useful genetic markers for twin differentiation.     

Chorionic villus sampling and acceptance rate of prenatal diagnosis

In this paper, we compared the acceptance rate of fetal diagnosis for β-thalassemia in three group of couples of Sardinian descent; the first counselled before DNA analysis was available, the second presenting after DNA analysis was introduced but too late for chorionic villus sampling and thus monitored by amniocyte DNA analysis and the third presenting within the first trimester after DNA analysis was introduced and thus in time for trophoblast DNA analysis. A higher proportion of couples from the latter group opted for fetal testing as compared to the 1st and 2nd group. These results indicate that in this population, introduction of 1st trimester diagnosis made prenatal testing acceptable to practically all counselled couples at risk.     

Neutrophil and monocyte β2-integrin expression in trisomic fetuses

Flow cytometry was used to measure neutrophil and monocyte β2-integrin expression in fetuses with trisomy 18 (n=7) and trisomy 21 (n=7) at 20–25 weeks' gestation. The values were compared with those of 112 chromosomally normal fetuses. There were no significant differences in β2-integrin expression between normal and aneuploid fetuses. These findings demonstrate that in trisomies 21 and 18, alteration in β2-integrin expression is unlikely to contribute to the pathogenesis of immunological deficiencies that have been observed in these aneuploidies both prenatally and postnatally.     

沼泽红假单胞菌累积聚β-羟基丁酸的研究

以沼泽红假单胞菌为材料,研究了不同培养条件下聚β-羟基丁酸(PHB)在微生物体内的累积情况,并用萃取、酯化及质谱联用(GC-MS)技术验证了菌体内累积的PHB。结果表明,在以醋酸钠为碳源、NH4+-N为氮源、中性pH的条件下,菌体内能够最大量的累积PHB,其累积量约为菌体(湿重)的50%。     

Influence of humic fractions on retention of isoproturon residues in two Moroccan soils

The influence of different fractions of soil organic matter on the retention of the herbicide isoproturon (IPU) has been evaluated. Water and methanol extractable residues of ¹⁴C labeled isoproturon have been determined in two Moroccan soils by β -counting–liquid chromatography. The quantification of bound residues in soil and in different fractions of soil humic substances has been performed using pyrolysis/scintillation-detected gas-chromatography. Microbial mineralization of the herbicide and soil organic matter has been also monitored. Retention of isoproturon residues after 30-days incubation ranged from 22% to 32% (non-extractable fraction). The radioactivity extracted in an aqueous environment was from 20% to 33% of the amount used for the treatment; meanwhile, methanol was able to extract another 48%. Both soils showed quantities of bound residues into the humin fraction higher than humic and fulvic acids. The total amount of residues retained into the organic matter of the soils was about 65 % of non-extractable fraction, and this percentage did not change with incubation time; on the contrary, the sorption rate of the retention reaction is mostly influenced by the clay fraction and organic content of the soil. Only a little part of the herbicide was mineralized during the experimental time.     

Overlooked biodiversity loss in tropical smallholder agriculture

Smallholder agriculture is the main driver of deforestation in the western Amazon, where terrestrial biodiversity reaches its global maximum. Understanding the biodiversity value of the resulting mosaics of cultivated and secondary forest is therefore crucial for conservation planning. However, Amazonian communities are organized across multiple forest types that support distinct species assemblages, and little is known about smallholder impacts across the range of forest types that are essential for sustaining biodiversity. We addressed this issue with a large-scale field inventory of birds (point counts) and trees (transects) in primary forest and smallholder agriculture in northern Peru across 3 forest types that are key for Amazonian biodiversity. For birds smallholder agriculture supported species richness comparable to primary forest within each forest type, but biotic homogenization across forest types resulted in substantial losses of biodiversity overall. These overall losses are invisible to studies that focus solely on upland (terra firma) forest. For trees biodiversity losses in upland forests dominated the signal across all habitats combined and homogenization across habitats did not exacerbate biodiversity loss. Proximity to forest strongly predicted the persistence of forest-associated bird and tree species in the smallholder mosaic, and because intact forest is ubiquitous in our study area, our results probably represent a best-case scenario for biodiversity in Amazonian agriculture. Land-use planning inside and outside protected areas should recognize that tropical smallholder agriculture has pervasive biodiversity impacts that are not apparent in typical studies that cover a single forest type. The full range of forest types must be surveyed to accurately assess biodiversity losses, and primary forests must be protected to prevent landscape-scale biodiversity loss.     

Immunoassay of red dyes based on the monoclonal antibody of β-naphthol

The objective of the present study was to develop a multi-analyte immunoassay for the determination of eight red dyes in food samples. Two dye intermediates (2-hydroxy-1-naphthoic acid and 1-amino-2-naphthol) were used as the haptens to produce the monoclonal antibodies. The obtained monoclonal antibodies recognized Sudan 1–4, Para red, Sudan red G, Sudan red B and Acid orange II simultaneously. After evaluation of different antibody/coating antigen combinations, a heterologous indirect competitive enzyme linked immunosorbent assay was developed to determine the eight red dyes in food samples (chili oil, chili powder, tomato sauce, hotpot seasoning). The crossreactivities to the eight analytes were in the range of 61%–79% (with β-naphthol as 100%), and the limits of detection were in the range of 1.3–1.9 ng/mL. The recoveries of the eight analytes from the fortified blank samples were in the range of 84.2%–115% with coefficients of variation lower than 18.3%. Therefore, this method could be used as a rapid and simple tool to detect the residues of the eight red dyes in foods.     

β-内酰胺类抗生素前处理技术及其残留的研究进展

β-内酰胺类是指在结构中有β-内酰胺环的一大类抗生素,在人类和动物疾病的治疗和预防上有着广泛的应用。抗生素的长期滥用造成药物在各种环境和动物源性食品中的残留,严重威胁环境生态和人体健康,因此各种样品中β-内酰胺类抗生素的分析检测方法成为当下研究热点。介绍了在测定β-内酰胺类抗生素残留时常用的前处理方法,包括液液微萃取技术、固相萃取技术和基质固相分散技术,同时研究了多种样品中β-内酰胺类抗生素残留的研究现状。