DNMT3L Is a Regulator of X Chromosome Compaction and Post-Meiotic Gene Transcription

Previous studies on the epigenetic regulator DNA methyltransferase 3-Like (DNMT3L), have demonstrated it is an essential regulator of paternal imprinting and early male meiosis. Dnmt3L is also a paternal effect gene, i.e., wild type offspring of heterozygous mutant sires display abnormal phenotypes suggesting the inheritance of aberrant epigenetic marks on the paternal chromosomes. In order to reveal the mechanisms underlying these paternal effects, we have assessed X chromosome meiotic compaction, XY chromosome aneuploidy rates and global transcription in meiotic and haploid germ cells from male mice heterozygous for Dnmt3L. XY bodies from Dnmt3L heterozygous males were significantly longer than those from wild types, and were associated with a three-fold increase in XY bearing sperm. Loss of a Dnmt3L allele resulted in deregulated expression of a large number of both X-linked and autosomal genes within meiotic cells, but more prominently in haploid germ cells. Data demonstrate that similar to embryonic stem cells, DNMT3L is involved in an auto-regulatory loop in germ cells wherein the loss of a Dnmt3L allele resulted in increased transcription from the remaining wild type allele. In contrast, however, within round spermatids, this auto-regulatory loop incorporated the alternative non-coding alternative transcripts. Consistent with the mRNA data, we have localized DNMT3L within spermatids and sperm and shown that the loss of a Dnmt3L allele results in a decreased DNMT3L content within sperm. These data demonstrate previously unrecognised roles for DNMT3L in late meiosis and in the transcriptional regulation of meiotic and post-meiotic germ cells. These data provide a potential mechanism for some cases of human Klinefelter's and Turner's syndromes

ICAR: endoscopic skull‐base surgery

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Call admission control for voice and data traffic in wireless communications

Call admission control (CAC) in multimedia wireless communications is to guarantee quality of service (QoS) to mobile users and to achieve a high resource utilization efficiency. It is a challenging issue due to user mobility, limited radio spectrum, heterogeneous nature of multimedia traffic. This paper proposes a CAC policy for a wireless system supporting both constant-rate voice calls and available-rate data calls. The parameters of the proposed policy is determined in a systematic way by using an optimization approach. Soft QoS (relaxed target QoS) is introduced to make a compromise between the QoS levels of the voice and data calls, respectively, in a heavy traffic load situation. Numerical results show that the proposed CAC policy can guarantee the QoS of all the users under most traffic conditions considered

Call admission control for wireless personal communications

Call admission control (CAC) in future wireless personal communication systems is to simultaneously achieve quality-of-service satisfaction and high resource utilization. It poses significant technical challenges due to scarce radio spectrum, user mobility, hostile wireless propagation environment, end-to-end connectivity, and dynamic nature of multimedia traffic. This paper aims at providing a survey on the existing literature related to the works on CAC for future wireless systems, especially in the wireless and combined wireless/wireline domains. As the concepts of the virtual connection tree (VCT) and cell cluster have been proposed to handle user mobility, both centralized CAC policies for systems using static VCT static cell cluster and distributed CAC policies for systems using dynamic VCT dynamic cell cluster are discussed. Comparisons among the various CAC solutions are made, problems that have been dealt with and problems that need to be tackled are identified for perspective researchers in this area

An in vitro study of the antioxidant activities and effect on human DNA of the Chinese herbal decoction ‘liu wei di huang’

A Chinese medicinal formulation, ‘Liu Wei Di Huang’, and its individual components have been tested for the genoprotective effect on human DNA by the comet assay. Results showed no DNA protection contributed by this prescription. However, the aqueous extracts of individual herbs, namely Cortex Moutan and Rhizoma Dioscoreae, were able to decrease by 10–15% the DNA stand break from hydrogen peroxide-mediated oxidative stress. This provides insight to further evaluate the interaction among herbs and the search for the active ingredient responsible for the DNA protective effect