Mutations and the conformational stability of globular proteins

The elucidation of the three-dimensional structure of now over 100 proteins provides the basis for describing the nature of interactions stabilizing native protein structure. To understand the forces responsible for maintaining the native structure, it is necessary to analyze the contributions of the specific forces like a hydrogen bond, a salt bridge or a hydrophobic interaction to the overall stability of a protein. Using mutant proteins carrying a single amino acid substitution, specific interactions in a protein can be altered and the effect can be studied. In this paper the results of such studies on stability variants of human haemoglobin and of T4 phage lysozyme are described.     

辽东湾浮游生物粒径结构稳定性分析

基于2012~2014年春、夏、秋、冬季辽东湾网采浮游生物及环境因子的调查资料,采用显微测微计法结合粒径谱理论分析了辽东湾南、北2个区域的浮游生物粒径结构特征,并构建了浮游生物群落稳定性评估模型.结果表明,辽东湾海域浮游生物不同营养级间能量传递效率近似相等,但生态转化效率偏低; 2012~2014年辽东湾南部区域稳定性系数平均为0.53,北部区域平均为0.47,南部区域浮游生物群落整体上较北部稳定,夏季表现更为明显,说明南部区域受环境胁迫影响较小;海水营养状况分析表明,北部区域属于富营养化水平较高海域,营养指数(E)平均为1.69,南部区域基本属于低营养水平,营养指数(E)平均为0.42,富营养化会导致系统偏离稳定状态;本文构建的浮游生物群落稳定性评估模型可尝试比较不同海域浮游生物群落的健康状况.     

McKusik-Kaufman syndrome: prenatal diagnosis,genetics and follow up

McKusick-Kaufman syndrome (MKKS) is a rare autosomal recessive genetic disease with classical hexadactyly and hydrocolpos in females and sometimes cardiac abnormality. We report such a case diagnosed just before birth with a favourable outcome. From this case we describe and discuss all the prenatal sonographic signs which are not always present. On the genetic side, the gene has recently been localized together with the mutation responsible for MKKS. The phenotypic relationship between MKKS which has a good prognosis and Bardet-Biedl syndrome (BBS) with a worse prognosis requires great caution before diagnosing MKKS and a long follow-up is necessary to recognize obesity, growth retardation and pigmentary retinitis. Copyright © 2002 John Wiley & Sons, Ltd.     

滦河三角洲典型潟湖-沙坝海岸岸线稳定性评价

滦河三角洲潟湖-沙坝海岸在我国海岸类型中最具特色,具有重要的教学和科研价值,在自然和人类共同作用下,海岸线一直处于动态的演变过程中。选取1987年、2000年和2014年三期遥感影像提取岸线数据,计算近年来潟湖-沙坝海岸岸线纵深度、年均变化速率和稳定性指数,分析各沙坝海岛岸线的稳定性。结果显示滦河三角洲潟湖-沙坝岸线以向陆蚀退为主,最大纵深度变化向陆蚀退近400 m,最大纵深度年均变化速度达-30 m/a,岸线以微侵蚀至严重侵蚀所占比例达到87%,74%海岛稳定性指数小于0.4。这主要是由于滦河中上游修建水库导致入海泥沙量减少,同时港口、养殖池的修建也对岸线稳定性起到负面影响。     

Effect of proteins, polysaccharides, and particle sizes on sludge dewaterability

Four batch experiments of hydrolysis and acidification were carried out to investigate the distributions of proteins (PN) and polysaccharides (PS) in the sludge, the PN/PS ratio, the particle sizes, and their relationship with sludge dewaterability (as determined by capillary suction time, CST). The sludge flocs were stratified through centrifugation- and ultrasound-based method into four fractions: (1) slime, (2) loosely bound extracellular polymeric substances (LB-EPS), (3) tightly bound EPS (TB-EPS), and (4) pellet. The results showed that PN was mainly partitioned in the pellet (80.7%) and TB-EPS (9.6%) fractions, while PS distributed evenly in the four fractions. During hydrolysis and acidification, PN was transferred from the pellet and TB-EPS fractions to the slime fraction, but PS had no significant transfer trends. The mean particle sizes of the sludge flocs decreased with hydrolysis and acidification. The pH had a more significant influence on the dewaterability of sludge flocs than temperature. Sludge dewaterability during hydrolysis and acidification processes greatly deteriorated from 9.7 s at raw sludge to 340–450 s under alkaline conditions. However, it was just slightly increased under acidic conditions. Further investigation suggested that CST was a ected by soluble PN, soluble PN/PS, and particle sizes of sludge flocs, but was a ected slightly by total PN, PS, or PN/PS in the whole sludge flocs and other fractions (except slime).     

Investigation into the genetics of fetal congenital lymphatic anomalies

Objective

Congenital lymphatic anomalies (LAs) arise due to defects in lymphatic development and often present in utero as pleural effusion, chylothorax, nuchal and soft tissue edema, ascites, or hydrops. Many LAs are caused by single nucleotide variants, which are not detected on routine prenatal testing.

Methods

Demographic data were compared between two subcohorts, those with clinically significant fetal edema (CSFE) and isolated fetal edema. A targeted variant analysis of LA genes was performed using American College of Medical Genetics criteria on whole exome sequencing (WES) data generated for 71 fetal edema cases who remained undiagnosed after standard workup.

Results

CSFE cases had poor outcomes, including preterm delivery, demise, and maternal preeclampsia. Pathogenic and likely pathogenic variants were identified in 7% (5/71) of cases, including variants in RASopathy genes, RASA1, SOS1, PTPN11, and a novel PIEZO1 variant. Variants of uncertain significance (VOUS) were identified in 45% (32/71) of cases. In CSFEs, VOUS were found in CELSR1, EPHB4, TIE1, PIEZO1, ITGA9, RASopathy genes, SOS1, SOS2, and RAF1.

Conclusions

WES identified pathogenic and likely pathogenic variants and VOUS in LA genes in 51% of fetal edema cases, supporting WES and expanded hydrops panels in cases of idiopathic fetal hydrops and fluid collections.     

Easurements of placental,decidual, and fetal proteins before and after chorionic villus sampling

Circulating placental [human chorionic gonadotrophin (hCG), Schwangerschafts protein 1 (SP1), pregnancy-associated plasma protein A (PAPP-A), decidual (pregnancy protein) 12 (PP12), and fetal alphafetoprotein (AFP)] proteins were measured immediately before and within 1 h in 18 women undergoing diagnostic chorionic villus sampling (CVS) in the first trimester. An elevation of serum AFP levels was consistently seen, while fluctuations in excess of 10 per cent of the pre-CVS levels of SP1 and PP12 were seen in the majority of patients. Fluctuations in hCG and PAPP-A were consistently less than 10 per cent of pre-CVS values. Post-CVS changes in levels were not apparently associated with any feature of the technique, the pregnancy, or its outcome (one missed abortion). As feto-maternal haemorrhage is a common event, anti-D should be offered to rhesus-negative women undergoing CVS. In the prediction of subsequent miscarriage, only hCG and PAPP-A measurements should be considered.     

Biodiversity,profitability, and vegetation structure in a Mexican coffee agroecosystem

We studied the relationships of bird and small mammal species richness, composition, and abundance to vegetation structure and economic profitability across a coffee intensification gradient in central Veracruz, Mexico. We conducted 2 years of point count censuses for summer resident birds, 2 years of Sherman live trapping for small mammals, and gathered vegetation structure data at 147 sampling points distributed over 16 sites spanning a cultivation intensification gradient. We calculated net annual revenue per hectare as an index of profitability from economic and management data collected during interviews with plantation owners/managers. Both the species richness and abundance of forest-affiliated birds were significantly greater in floristically and structurally diverse ‘bajo monte’ coffee and forest compared with commercial polyculture coffee, which was, in turn, significantly richer than statistically indistinguishable specialized shade and sun coffee. Mammal capture rates were extremely low at all but two sites. Forest bird species richness and abundance were explained by multiple linear regression models that included statistically significant effects of shade cover, percent of trees with epiphytes, and canopy height. We found no clear relationship between profitability and biodiversity, with biodiverse bajo monte coffee plantations ranking among the most profitable under all price scenarios. The high profitability of biodiverse bajo monte coffee systems was not dependent on the inclusion of long-term environmental costs or premium pricing systems. Our results demonstrate that high-biodiversity coffee cultivation can be compatible with high profitability, and has significant potential for conserving biodiversity in coffee-growing regions, but only as a substitute for low-biodiversity coffee cultivation, not forest.     

Equilibration times,compound selectivity,and stability of diffusion samplers for collection of ground-water VOC concentrations

Vapor-filled polyethylene diffusion samplers (typically used to locate discharge zones of volatile organic compound contaminated ground water beneath streams and lakes) and water-filled polyethylene diffusion bag samplers (typically used to obtain volatile organic compound concentrations in ground-water at wells) were tested to determine compound selectivity, equilibration times, and sample stability. The aqueous concentrations of several volatile organic compounds obtained from within water-filled diffusion samplers closely matched concentrations in ambient water outside the samplers. An exception was methyl-tert-butyl ether, which was detectable, but not reliably quantifiable using the diffusion samplers. The samplers equilibrated to a variety of volatile organic compounds within 24 h for vapor-filled passive diffusion vial samplers and within 48 h for water-filled passive diffusion bag samplers. Under field conditions, however, a longer equilibration time may be required to account for environmental disturbances caused by sampler deployment. An equilibrium period for both vapor- and water-filled diffusion samplers of approximately 2 weeks probably is adequate for most investigations in sandy formations. Longer times may be required for diffusion-sampler equilibration in poorly permeable sediment. The vapor-filled samplers should be capped and water from the diffusion bag samplers should be transferred to sampling vials immediately upon recovery to avoid volatilization losses of the gasses.     

福建宁德晴川湾海域鱼类群落结构及其时空变动

福建宁德晴川湾是闽东渔场的中心区域,但针对该区域鱼类群落结构的研究相对欠缺。本研究在2020年4月和10月开展了两次底拖网调查,旨在通过对晴川湾海域鱼类群落结构及其时空变动的分析,探究环境因子对该海域鱼类群落的影响。结果显示：本次调查共采集到鱼类11目29科49属55种,其中,30种为洄游性鱼类;春季优势种主要为孔虾虎鱼（Trypauchen vagina）,秋季优势种为龙头鱼（Harpadon nehereus）;多样性指数存在季节差异,具体表现为春季平均Shannon-Wiener多样性指数和Pielou均匀度指数（1.80和0.70）高于秋季（1.36和0.47）,秋季的物种丰富度（2.70）显著高于春季（2.48）;不同站位间各环境参数不存在显著差异,同一站位内春、秋两季的水温、盐度、溶解氧和叶绿素a等均存在显著差异。RDA排序结果显示,春季鱼类群落受叶绿素a浓度影响显著;秋季鱼类群落则受盐度、溶解氧影响显著。本调查填补了宁德晴川湾海域鱼业资源现状的空白,同时为该海域渔业资源的可持续利用和有效管理以及海区生态系统修复提供了参考依据。     

Robust prediction of chatter stability in milling based on the analytical chatter stability

A major obstacle that limits the productivity in machining operations is the presence of machine tool chatter. Machining is a dynamic process and chatter behavior depends upon a number of different aspects including spindle speeds, material properties, tool geometry, and even the location of tool respect to the rest of machine. Many of the traditional models used to predict chatter stability lobes assume that parameters such as natural frequency, stiffness, and cutting coefficients remain constant. In reality, these parameters vary and they affect the chatter stability. The uncertainty in these parameters can be taken into consideration by employing the robust stability theory into a two degree of freedom milling model. Utilizing the Edge theorem and the Zero Exclusion condition, a robust chatter stability model, based on the analytical chatter stability milling model, is developed. This improves the reliability compared to the projected pseudo single degree of freedom model. The method is verified experimentally for milling operations while considering a changing natural frequency and cutting coefficient.     

陕西关中地区土地资源的优化配置

从分析陕西省关中地区土地资源利用现状结构特征及存在问题入手,运用灰色线性规划模型对土地利用结构进行优化配置。模型选取多个影响土地利用结构因子,并通过预测未来关中地区各行各业之用地需求及用地限制从而确定出各因子适当参数,进行模拟后得出典型备选方案。最后从综合效益及可行性双方面考虑,经层次分析法择出未来关中地区最优土地利用决策方案。     

论环境意识的组成、结构与发展

环境意识是一种具有多维属性的社会意识,本文分别从环境意识的静态组成、深度层次、人群层次、时间属性和空间属性等5个方面探讨了环境意识的组成、结构和分类,揭示了环境意识的动态过程和发展特征,对环境意识的发展规律进行了理论概括.文章还阐述了在现代信息走向更加开放情况下环境意识的传播途径和环境教育的基本原则.