Prenatal diagnosis of mosaic 4p – in a fetus with trisomy 21

Mosaicism for the Wolf-Hirschhorn syndrome, del(4)(p16), is extremely rare and has not been reported in association with a numerical chromosome abnormality. We report the prenatal diagnosis of mosaic del(4)(p16) and non-mosaic trisomy 21 in a 16-week female fetus. The pregnancy ended in spontaneous abortion at 34 weeks secondary to fetal demise. The fetus had features of both 4p – and trisomy 21.     

Technical and theoretical considerations in the HLA typing of amniotic fluid cells for prenatal diagnosis and paternity testing

HLA typing of amniotic fluid cells has been used for the prenatal diagnosis of the HLA linked diseases congenital adrenal hyperplasia (21-OH-deficiency (21-OH-def) type) and complement C4 deficiency and it has also been used for the prenatal de termination of paternity. There are, however, technical difficulties in this test associated with the weak expression of some B locus antigens on amniotic fluid cells, and theoretical difficulties related to associations between particular HLA antigens and the 21-OH-def allele. Since certain HLA-B locus antigens are found in significantly increased frequencies among patients with 21-OH-def, there is a relatively high incidence of HLA-B homozygosity among the patients and over 40 percent of the parents of these patients share one or more HLA-B locus antigens. Results of some prenatal HLA typing tests may thus be difficult to interpret, and supplementary tests should be used whenever possible. HLA typing of amniotic cells is, however, the only available procedure for prenatal diagnosis of C4 deficiency and it is the best available procedure for prenatal determination of paternity. A modification of our original procedure allows HLA typing to be performed with increased numbers of HLA typing sera, and sera with optimum reactivity for amniotic fluid cells have now been selected for the definition of most of the more commonly expressed HLA antigens. Although amniotic fluid cells do not express DR antigens, amniotic fluid cells can be typed for the HLA-linked marker glyoxalase I (GLO) and this may be the informative for prenatal diagnosis in some cases.     

Prenatal diagnosis of 21-hydroxylase deficiency by rflp analysis of the 21-hydroxylase,complement C4, and HLA class II genes

In 19 pregnancies at risk for 21-hydroxylase deficiency (21OHD) in 18 families with at lea one affected child, prenatal diagnosis was performed by RFLP analysis using the enzymi Taq I and EcoRI and the DNA probes specific for the 21 OH genes, the closely linke complement C4 genes and the highly polymorphic HLA class II genes DRB, DQB, and DPI For fetal DNA analysis either chorionic villi or cultivated amniotic cells were used. In all 1 cases, a clear prenatal diagnosis was possible either with the 21OH probe alone or in mo cases, by combining the results of the different closely linked loci.     

厌氧水环境中噬菌体MS2的存活和团聚特性及理化因素的影响

为探究病毒在厌氧水环境中的存活特性,以噬菌体MS2为模式病毒,采用双层平板法进行噬菌体MS2的定量检测,研究温度、pH值、悬浮颗粒物、乙酸等理化条件对噬菌体MS2的影响,分析其衰减动力学特征,并通过测定Zeta电位和噬菌斑直径考察噬菌体颗粒在不同条件下的聚集状况.结果表明,在厌氧水环境中,噬菌体MS2的衰减符合一阶指数衰减模型.在众多研究因素中,温度是影响噬菌体MS2存活的最主要因素.噬菌体MS2在4,17,25和35℃时的T₉₀分别为20.36,6.14,5.15和0.46d.35℃条件下12h后噬菌体失活率高达2.44lg,而4℃条件下7d后噬菌体失活率仅有0.78lg.增加乙酸浓度能明显提高噬菌体MS2的衰减速率.低pH值和悬浮颗粒物条件会促进噬菌体的团聚,使噬菌体颗粒Zeta电位降低,水力学直径增大,但悬浮颗粒物浓度过高会影响颗粒间的静电作用.噬菌体的团聚也增加了噬菌斑的直径,pH=6和20mg/L的悬浮颗粒物条件下,直径1.0mm以上的大噬菌斑数量占比分别达到了45.61%和57.74%.明确厌氧水环境中各种理化因素对噬菌体MS2的影响,可为水环境病毒控制提供科学依据.     

The promissory note: COP 21 and the Paris Climate Agreement

The 2015 UN climate negotiations in Paris resulted in an inclusive, binding treaty that succeeds the Kyoto Protocol. In contrast to the failure at Copenhagen in 2009, the Paris negotiations are therefore seen as a major diplomatic success that has regenerated faith in the United Nations Framework Convention on Climate Change as a forum for dynamic multilateralism. The Paris Agreement provides a robust framework for ratcheting up efforts to combat global warming. However, the Agreement’s value will remain unclear for some time. The historical path to the Paris accord is outlined, and a preliminary assessment is offered of its key elements and outcomes.     

Modeling the Effects of Potential Salinity Shifts on the Recovery of Striped Bass in the Savannah River Estuary,Georgia–South Carolina,United States

Increased salinity in spawning and nursery grounds in the Savannah River estuary was cited as the primary cause of a 97% decrease in adult striped bass (Morone saxatilis) and a concomitant 96% decrease in striped bass egg production. Restoration efforts focused on environmental remediation and stock enhancement have resulted in restored salinity patterns and increased egg and adult abundances. However, future water needs or harbor development may preclude further recovery by reducing freshwater inflow or increasing salinity intrusion. To assess the effect of potential changes in the salinity regime, we developed models relating discharge, tidal phase, and salinity to striped bass egg and early larval survival and re-cast these in a quantitative Bayesian belief network. The model indicated that a small upstream shift (≤1.67 km) in the salinity regime would have the least impact on striped bass early life history survival, whereas shifts >1.67 km would have progressively larger impacts, with a 8.33-km shift potentially reducing our estimated survival probability by >28%. Such an impact could have cumulative and long-term detrimental effects on the recovery of the Savannah River striped bass population. The available salinity data were collected during average and low flows, so our model represents some typical and some extreme conditions during a striped bass spawning season. Our model is a relatively simplistic, “first-order” attempt at evaluating potential effects of changes in the Savannah River estuarine salinity regime and points to areas of concern and potential future research.