Resistance to CD95/Fas-induced and ceramide-mediated apoptosis of human melanoma cells is caused by a defective mitochondrial cytochrome c release

Intracellular CD95/Fas-signaling pathways have not been investigated in melanoma yet. Two different CD95 receptor-induced apoptotic pathways are presently known in other cell types: (i) direct activation of caspase-8 and (ii) induction of ceramide-mediated mitochondrial activation, both leading to subsequent caspase-3 activation. In the present study, five of 11 melanoma cell populations were shown to release cytochrome c from mitochondria, which activates caspase-3 and finally results in DNA fragmentation upon treatment with the agonistic monoclonal antibody CH-11. In contrast, this apoptotic pathway was not activated in the remaining six melanoma cell populations. Interestingly, the susceptibility of melanoma cells to CD95L/FasL-triggered cell death was clearly correlated with N-acetylsphingosine-mediated apoptosis. Our results are in line with a defect upstream of mitochondrial cytochrome c release in resistant cells.     

Lower-than-expected linkage disequilibrium between tightly linked markers in humans suggests a role for gene conversion

Understanding the pattern of linkage disequilibrium (LD) in the human genome is important both for successful implementation of disease-gene mapping approaches and for inferences about human demographic histories. Previous studies have examined LD between loci within single genes or confined genomic regions, which may not be representative of the genome; between loci separated by large distances, where little LD is seen; or in population groups that differ from one study to the next. We measured LD in a large set of locus pairs distributed throughout the genome, with loci within each pair separated by short distances (average 124 bp). Given current models of the history of the human population, nearly all pairs of loci at such short distances would be expected to show complete LD as a consequence of lack of recombination in the short interval. Contrary to this expectation, a significant fraction of pairs showed incomplete LD. A standard model of recombination applied to these data leads to an estimate of effective human population size of 110,000. This estimate is an order of magnitude higher than most estimates based on nucleotide diversity. The most likely explanation of this discrepancy is that gene conversion increases the apparent rate of recombination between nearby loci.     

A New Species of Allosathes Gaud, Atyeo & Berla (Astigmata: Crypturoptidae) on Feathers of the Chilean Tinamou, Nothoprocta perdicaria (Tinamiformes: Tinamidae) in Chile

Allosathes anitae n. sp. Casanueva & González-Acu?a (Astigmata: Crypturoptidae), collected on the Chilean tinamou Nothoprocta perdicaria (Tinamiformes: Tinamidae) from different localities of the ?uble Province, Chile, is described. Comments on its affinities and differences with Allosathes anepiandrius Gaud, Atyeo & Berla are also included.     

Outer Segment Formation of Transplanted Photoreceptor Precursor Cells

Transplantation of photoreceptor precursor cells (PPCs) into the retina represents a promising treatment for cell replacement in blinding diseases characterized by photoreceptor loss. In preclinical studies, we and others demonstrated that grafted PPCs integrate into the host outer nuclear layer (ONL) and develop into mature photoreceptors. However, a key feature of light detecting photoreceptors, the outer segment (OS) with natively aligned disc membrane staples, has not been studied in detail following transplantation. Therefore, we used as donor cells PPCs isolated from neonatal double transgenic reporter mice in which OSs are selectively labeled by green fluorescent protein while cell bodies are highlighted by red fluorescent protein. PPCs were enriched using CD73-based magnetic associated cell sorting and subsequently transplanted into either adult wild-type or a model of autosomal-dominant retinal degeneration mice. Three weeks post-transplantation, donor photoreceptors were identified based on fluorescent-reporter expression and OS formation was monitored at light and electron microscopy levels. Donor cells that properly integrated into the host wild-type retina developed OSs with the formation of a connecting cilium and well-aligned disc membrane staples similar to the surrounding native cells of the host. Surprisingly, the majority of not-integrated PPCs that remained in the sub-retinal space also generated native-like OSs in wild-type mice and those affected by retinal degeneration. Moreover, they showed an improved photoreceptor maturation and OS formation by comparison to donor cells located on the vitreous side suggesting that environmental cues influence the PPC differentiation and maturation. We conclude that transplanted PPCs, whether integrated or not into the host ONL, are able to generate the cellular structure for effective light detection, a phenomenon observed in wild-type as well as in degenerated retinas. Given that patients suffering from retinitis pigmentosa lose almost all photoreceptors, our findings are of utmost importance for the development of cell-based therapies.     

Papiine herpesvirus 2 as a Predictive Model for Drug Sensitivity of Macacine herpesvirus 1 (Monkey B Virus)

Monkey B virus (Macacine herpesvirus 1; BV) is endemic in macaques. BV (a BSL4 agent) is the primary zoonotic concern for persons working with macaques in research, and human BV infections frequently are fatal. We assessed the use of a BSL2 baboon herpesvirus (Papiine herpesvirus 1; HVP2) for predicting the drug sensitivity of BV by comparing the sensitivity of the 2 viruses to 12 antiherpetic drugs. Plaque reduction assays showed that 4 drugs (HBPG, BVdU, PFA, and BrdU) were ineffective against both viruses. Of the 8 effective drugs, both viruses were most sensitive to TFT, whereas sensitivity to the remaining 7 drugs varied between BV and HVP2 as well as between strains of HVP2. In addition, the efficacy of 5 drugs (ACV, PCV, GCV, CDV, and EDU) was tested by using a murine model. ACV and EDU were completely ineffective against both HVP2 and BV, and high doses of PCV only delayed death by a few days. GCV and CDV both protected mice against death, and CDV also prevented the development of neurologic symptoms. When the initiation of drug therapy was delayed until after virus gained access to the CNS, both GCV and CDV were ineffective. The similarity of the drug sensitivities of HVP2 and BV in both models validates the use of HVP2 as a BSL2 level model that can be used to predict drug sensitivity of BV. The greater efficacy of CDV relative to GCV suggests the potential for use of CDV in the treatment of zoonotic BV infections.Abbreviations: ACV, acyclovir; AraA, 9-β-D-arabinofuranosyl-adenine; BrdU, 5-bromo-2′-deoxyuridine; BV, monkey B virus; BVdU, (E)-5-(2-bromovinyl)-2′-deoxyuridine; CDV, cidofovir; EDU, 5-ethyl-2′-deoxyuridine; GCV, ganciclovir; HBPG, 9-(4-hydroxybutyl)-N²-phenylguanine; HSV, herpes simplex virus; HVP2, Herpesvirus papio 2; IUdR, 5-iodo-2’-deoxyuridine; PCV, penciclovir; PFA, phosphonoformic acid; TFT, trifluorothymidineMacacine herpesvirus 1 (monkey B virus; BV) is an alpha-herpesvirus of macaque monkeys and is closely related to human herpes simplex virus (HSV) types 1 and 2.^8,11,27 Although BV primarily causes asymptomatic or mild, self-limiting disease in healthy macaques, the virus is extremely neurovirulent when transmitted via bites or scratches to other nonmacaque primate species, including humans. Although human infections are not common, approximately 80% of untreated patients die of BV infection, and survivors frequently continue to suffer from neurologic sequelae. As a consequence of its lethality in humans, BV is classified as a BSL4 pathogen³ and is the single most serious zoonotic concern for veterinary and research personnel who work with macaques. The increasing popularity of ecotourism to monkey temples in Southeast Asia, where tourists and wild, BV-infected macaque populations come into direct contact, represents another potential concern for zoonotic BV infections.^9,12,13,21The antiviral drugs recommended for use in treating BV infections all were originally developed for treatment of HSV infections.^4,18 Because the genes encoding the enzymes targeted by these drugs are conserved between these viruses, BV is sensitive to many of these anti-HSV drugs. However, compared with HSV, BV is less sensitive to these drugs.^2,10,14 Although more effective drugs are needed for the treatment of BV infections, the biohazardous nature of and facility requirements associated with studying a BSL4 agent severely limit research on BV. A potential solution to this problem is using a closely related virus whose biologic and molecular properties are very similar to those of BV as a surrogate or model system in which preliminary research can be conducted safely, leaving only confirmative testing to be done with infectious BV.Baboons carry an alpha-herpesvirus (Papiine herpesvirus 2; HVP2) that is biologically and genetically very similar to BV and HSV.^7,8,15,26 In mice, most HVP2 isolates are extremely neurovirulent and closely reflect the pathogenesis of BV in mice^20,23 At the antigenic level, HVP2 and BV are so similar that HVP2 has found use as an alternative antigen for diagnostic BV serology.^17,25,28 Despite the virus''s similarity to BV, HVP2 infections have never been reported in humans. Consequently, HVP2 is rated as a BSL2 pathogen and, as such, HVP2 can be used under BSL2/ABSL2 containment. This study was conducted to assess the potential use of HVP2 as a surrogate model system for predicting the sensitivity of BV to antiviral drugs.     

一种钒配合物LMC 抑制DNA 拓扑异构酶?的抗肿瘤作用

目的：探讨钒配合物LMc对拓扑异构酶Ⅰ、Ⅱ（Topo-Ⅰ、Topo-Ⅱ）的影响及其抗肿瘤活性。方法：采用DNA松弛实验观察LMC对Topo-Ⅰ、活性的影响并探讨其相关分子作用机制;采用MTT法、流式细胞术在细胞水平观察了IMC的抗肿瘤作用。结果：LMC可明显抑制Topo-Ⅰ活性,对Topo-Ⅱ无明显抑制作用,对多种肿瘤细胞株A549、Hela、BEL-7402具有明显抑制生长的作用,且可将细胞阻断在G2／M期,而对正常细胞株L-02生长无明显影响。结论：钒配合物LMC具有抑制Topo-Ⅰ活性而发挥抗肿瘤的作用。     

Cellular models for the study of the pharmacology and signaling of melanin-concentrating hormone receptors

Cellular models for the study of the neuropeptide melanin-concentrating hormone (MCH) have become indispensable tools for pharmacological profiling and signaling analysis of MCH and its synthetic analogues. Although expression of MCH receptors is most abundant in the brain, MCH-R(1) is also found in different peripheral tissues. Therefore, not only cell lines derived from nervous tissue but also from peripheral tissues that naturally express MCH receptors have been used to study receptor signaling and regulation. For screening of novel compounds, however, heterologous expression of MCH-R(1) or MCH-R(2) genes in HEK293, Chinese hamster ovary, COS-7, or 3T3-L1 cells, or amplified MCH-R(1) expression/signaling in IRM23 cells transfected with the G(q) protein gene are the preferred tools because of more distinct pharmacological effects induced by MCH, which include inhibition of cAMP formation, stimulation of inositol triphosphate production, increase in intracellular free Ca(2+) and/or activation of mitogen-activated protein kinases. Most of the published data originate from this type of model system, whereas data based on studies with cell lines endogenously expressing MCH receptors are more limited. This review presents an update on the different cellular models currently used for the analysis of MCH receptor interaction and signaling.     

Sequence diversity, natural selection and linkage disequilibrium in the human T cell receptor alpha/delta locus

T cell receptors (TR), through their interaction with the major histocompatibility complex, play a central role in immune responsiveness and potentially immune-related disorders. We resequenced all 57 variable (V) genes in the human T cell receptor alpha and delta (TRA/TRD) locus in 40 individuals of Northern European, Mexican, African-American and Chinese descent. Two hundred and eighty-four single nucleotide polymorphisms (SNPs) were identified. The distribution of SNPs between V genes was heterogeneous, with an average of five SNPs per gene and a range of zero to 15. We describe the patterns of linkage disequilibrium for these newly discovered SNPs and compare these patterns with other emerging large-scale datasets (e.g. Perlegen and HapMap projects) to place our findings into a framework for future analysis of genotype–phenotype associations across this locus. Furthermore, we explore signatures of natural selection across V genes. We find evidence of strong directional selection at this locus as evidenced by unusually high values of F _st Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.