De novo deletions of SNRPN exon 1 in early human and mouse embryos result in a paternal to maternal imprint switch

Prader-Willi syndrome (PWS) is a neurogenetic disease characterized by infantile hypotonia, gonadal hypoplasia, obsessive behaviour and neonatal feeding difficulties followed by hyperphagia, leading to profound obesity. PWS is due to a lack of paternal genetic information at 15q11-q13 (ref. 2). Five imprinted, paternally expressed genes map to the PWS region, MKRN3 (ref. 3), NDN (ref. 4), NDNL1 (ref. 5), SNRPN (refs 6-8 ) and IPW (ref. 9), as well as two poorly characterized framents designated PAR-1 and PAR-5 (ref. 10). Imprinting of this region involves a bipartite 'imprinting centre' (IC), which overlaps SNRPN (refs 10,11). Deletion of the SNRPN promoter/exon 1 region (the PWS IC element) appears to impair the establishment of the paternal imprint in the male germ line and leads to PWS. Here we report a PWS family in which the father is mosaic for an IC deletion on his paternal chromosome. The deletion chromosome has acquired a maternal methylation imprint in his somatic cells. We have made identical findings in chimaeric mice generated from two independent embryonic stem (ES) cell lines harbouring a similar deletion. Our studies demonstrate that the PWS IC element is not only required for the establishment of the paternal imprint, but also for its postzygotic maintenance.     

Epigenetic inactivation of SFRP genes allows constitutive WNT signaling in colorectal cancer

Aberrant WNT pathway signaling is an early progression event in 90% of colorectal cancers. It occurs through mutations mainly of APC and less often of CTNNB1 (encoding beta-catenin) or AXIN2 (encoding axin-2, also known as conductin). These mutations allow ligand-independent WNT signaling that culminates in abnormal accumulation of free beta-catenin in the nucleus. We previously identified frequent promoter hypermethylation and gene silencing of the genes encoding secreted frizzled-related proteins (SFRPs) in colorectal cancer. SFRPs possess a domain similar to one in the WNT-receptor frizzled proteins and can inhibit WNT receptor binding to downregulate pathway signaling during development. Here we show that restoration of SFRP function in colorectal cancer cells attenuates WNT signaling even in the presence of downstream mutations. We also show that the epigenetic loss of SFRP function occurs early in colorectal cancer progression and may thus provide constitutive WNT signaling that is required to complement downstream mutations in the evolution of colorectal cancer.     

一种抗裁剪和旋转的盲水印嵌入新方法

在满足提取水印完整性的前提下，提出了一种可抗相应角度裁剪和旋转攻击的水印嵌入新方法，它以掩饰图像中心为对称点，将图像按一定角度要求划分成均等的若干块，其中每一块均可通过给定角度倍数的旋转与参考块重合。通过对水印的裁剪和旋转攻击方法的分析，给出将对称思想与多次嵌入方法相结合的解决方案，分析并证明了它对如上的角度裁剪和旋转攻击具有鲁棒性。具体介绍了实现不印时的嵌入策略，并讨论了嵌入量和鲁棒性之间的关系。本文提出的新方法，其特点是不依赖于工作域的选择，同时也与具体水印嵌入算法无关。试验结果表明它对于抵抗相应攻击具有有效性。     

One Way to Eliminate Corruption-Educating People——Brief Introduction on Bid

This article,according to the author's working experience in a hydropewer project,briefly introducessome basic knowledge about bidding process and sample contract document.It is aiming at giving a commonknowledge to the students who will be involved in work relating to bid after their graduation in the college.It ishoped that this kind of knowledge can help people properly use funds for a project and thus corruption can beminimized.     

积极心理学及其在课堂教学中的应用

积极心理学是美国心理学界兴起的一个新的研究领域。它是利用心理学目前已比较完善和有效的实验方法与测量手段,来研究人类的力量和美德等积极方面的一个心理学思潮。从当前的发展态势来看,积极心理学不仅仅在心理学领域里取得了巨大的成就,而且其思想已经渗透进了心理治疗、教育、社会学、管理学和经济学等多个社会领域。本文主要关注积极心理学对课堂教学的积极作用,即积极心理学可以帮助学生培养积极情绪、解决教师的职业倦怠问题和建立良好的师生关系。     

Morphological variability and genetic diversity in five species of Skeletonema （Bacillariophyta）

Twelve strains of Skeletonema from Chinese coastal waters and another strain from the West Sea of Korea were examined using light microscopy （LM）, scanning and transmission electron microscopy （SEM, TEM）, and small subunit （SSU） rDNA sequence analysis. We identified four species of Skeletonema： S. marinoi Sarno et Zingone, S. subsalsum （A.Cleve） Bethge, S. dohrnii Sarno et Kooistra, S. trop- icum Cleve, as well as a Skeletonerna-like species. These are the first records of S. rnarinoi, S. dohrnii and S. subsalsurn in China. The Skeletonema-like species, MMDLS067, was isolated from the estuary of the Changjiang River. The morphologic and phylogenetic characteristics of this species are not correspond to those of any previously published Skeletonerna species. The intercalary fultoportula pro- cesses （IFPPs） has long open tubes, and the intercalary rimoportula process （IRP） is short and located inside the rim of the IFPPs. Phylogenetic analysis revealed that MMDL5630 clustered with S. tropicurn in the NJ and MP trees, but its IRPs differed from those of previously described specimens of S. tropicum. The IRP is partially open, with an elongated opening at the base of the tube, and is longer than the IFPPs. Some specimens of S. marinoi and S. dohrnii also have longer tubular IRPs than the IFPPs. Compared to pre- viously described specimens of S. rnar＆oi and S. dohrnii, these two specimens we identified have shorter IRPs. Our results reflect the ambiguity and diversity of Skeletonema taxonomy. They are also significant for the future identification and management of red tides caused by Skeletonerna in the seas around China.     

充分发挥督导作用 提高我院教育质量

在目前高校教学质量评价及反馈机制尚未十分成熟和完善之际,如何充分发挥教学督导组作用,是直接关系到教学改革深化和教学质量提高的重要环节之一。结合我院实际,就如何发挥教学督导作用进行论述,以促进我院教学质量的提高。     

Non-Uniform APSK Optimization for BICM Systems

Traditional Amplitude Phase Shift Keying(APSK) consists of rings with points uniformly spaced. By giving up this uniform-spacing feature, we propose an APSK optimization method based on the uniform APSK with Gray labeling(Gray-APSK). The aim of the optimization is to maximize the Generalized Mutual Information(GMI)of Bit-Interleaved Coded Modulation(BICM) for the targeted code rate and channel. We show that our optimized non-uniform APSK could offer further performance gain compared with the conventional uniform Gray-APSK and considerably outperforms the traditional quadrature amplitude modulation at the targeted SNR and channel.     

Joint optimization of serving node selection and wireless resources allocation for transactions data in mobile blockchain enhanced Internet of Things

With the increased emphasis on data security in the Internet of Things(IoT), blockchain has received more and more attention.Due to the computing consuming characteristics of blockchain, mobile edge computing(MEC) is integrated into IoT.However, how to efficiently use edge computing resources to process the computing tasks of blockchain from IoT devices has not been fully studied.In this paper, the MEC and blockchain-enhanced IoT is considered.The transactions recording the data or other applica...