Genome-wide scan for familial nasopharyngeal carcinoma reveals evidence of linkage to chromosome 4

Nasopharyngeal carcinoma (NPC) occurs with high frequency in Asian populations, especially among people of Cantonese ancestry. In areas with high incidence, NPC clusters in families, which suggests that both geography and genetics may influence disease risk. Although the HLA-Bw46 locus is associated with increased risk of NPC, no predisposing genes have been identified so far. Here we report the results of a genome-wide search carried out in families at high risk of NPC from Guangdong Province, China. Parametric analyses provide evidence of linkage to the D4S405 marker on chromosome 4 with a logarithm of odds for linkage (lod) score of 3.06 and a heterogeneity-adjusted lod (hlod) score of 3.21. Fine mapping with additional markers flanking D4S405 resulted in a lod score of 3.54 and hlod score of 3.67 for the region 4p15.1-q12. Multipoint nonparametric linkage analysis gives lod scores of 3.54 at D4S405 (P = 5.4 x 10(-5)) and 4.2 at D4S3002 (P = 1.1 x 10(-5)), which is positioned 4.5 cM away from D4S405. When Epstein Barr virus antibody titer was included as a covariate, the lod scores reached 4.70 (P = 2.0 x 10(-5)) and 5.36 (P = 4.36 x 10(-6)) for D4S405 and D4S3002, respectively. Our findings provide evidence of a major susceptibility locus for NPC on chromosome 4 in a subset of families.     

Bunching of fractionally charged quasiparticles tunnelling through high-potential barriers

Shot noise measurements have been used to measure the charge of quasiparticles in the fractional quantum Hall (FQH) regime. To induce shot noise in an otherwise noiseless current of quasiparticles, a barrier is placed in its path to cause weak backscattering. The measured shot noise is proportional to the charge of the quasiparticles; for example, at filling factor v=1/3, noise corresponding to q=e/3 appears. For increasingly opaque barriers, the measured charge increases monotonically, approaching q=e asymptotically. It was therefore believed that only electrons, or alternatively, three bunched quasiparticles, can tunnel through high-potential barriers encountered by a noiseless current of quasiparticles. Here we investigate the interaction of e/3 quasiparticles with a strong barrier in FQH samples and find that bunching of quasiparticles in the strong backscattering limit depends on the average dilution of the quasiparticle current. For a very dilute current, bunching ceases altogether and the transferred charge approaches q=e/3. This surprising result demonstrates that quasiparticles can tunnel individually through high-potential barriers originally thought to be opaque for them.     

A proteasomal ATPase subunit recognizes the polyubiquitin degradation signal

The 26S proteasome is the chief site of regulatory protein turnover in eukaryotic cells. It comprises one 20S catalytic complex (composed of four stacked rings of seven members) and two axially positioned 19S regulatory complexes (each containing about 18 subunits) that control substrate access to the catalytic chamber. In most cases, targeting to the 26S proteasome depends on tagging of the substrate with a specific type of polyubiquitin chain. Recognition of this signal is followed by substrate unfolding and translocation, which are presumably catalysed by one or more of six distinct AAA ATPases located in the base-a ring-like 19S subdomain that abuts the axial pore of the 20S complex and exhibits chaperone activity in vitro. Despite the importance of polyubiquitin chain recognition in proteasome function, the site of this signal's interaction with the 19S complex has not been identified previously. Here we use crosslinking to a reactive polyubiquitin chain to show that a specific ATPase subunit, S6' (also known as Rpt5), contacts the bound chain. The interaction of this signal with 26S proteasomes is modulated by ATP hydrolysis. Our results suggest that productive recognition of the proteolytic signal, as well as proteasome assembly and substrate unfolding, are ATP-dependent events.     

遍历测度的一个定理及其应用

设f是紧度量空间上的连续自映射。本文证明,如果f的所有非渐近周期的非游荡点的集合的基数是可列的,则f的遍历测度是它的周期轨道原子测度,且f的拓扑熵为零。作为推论还得到,逐点周期映射有零拓扑熵。另外,当f没有周期点时,其非游荡点的集合的基数是不可列的。     

Evaporative cooling in the zebra finch

Zusammenfassung O₂-Verbrauch und Gesamt-Wasserverdunstung wurden bei australischen Zebrafinken gemessen. Bei geringem Wärmeaustausch zwischen Körper und Umgebung durch Strahlung, Konvektion und Ableitung können diese Wüstenvögel den für die Wärmebilanz erforderlichen Wärmeabfluss einzig durch Verdunstung auf dem normalen Niveau halten. Eine solche Fähigkeit ist bei Passeres bisher nicht beobachtet worden.

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This investigation was supported in part by funds provided for medical and biological research by State of Washington Initiative Measure No. 171, and in part by a Public Health Service research career program award (No. AM-K3-18, 370) from the National Institute of Arthritis and Metabolic Diseases.     

A neurite-receptor complex in the avian lung: Electron microscopical observations

Résumé L'examen au microscope électronique du bronchus primaire intrapulmonaire deGallus domesticus a révelé la présence d'un complexe neurite-récepteur très semblable aux cellules du glomus carotidien des mammifères, et aux cellules de Merkel qui se trouvent dans les structures épidermiques des vertébrés. La fonction possible chémorécepteur ou méchanorécepteur de ces cellules est discutée.     

New synthesis of amphiphilic copolymers PE-<Emphasis Type="Italic">g</Emphasis>-PEO via esterfication

A new series of high molecular weight amphiphilic graft compolymaers PE-g-PEO has been prepared,The esterifications between PE-p-MS-g-MA and PEO with OH group at the chain end are carried out under different conditions,The compositions of these graft copolymers are studied by NMR and FTIR ,It is found to be a converient and efficient way to prepare high molecular weight PE-g-PEO graft copolymers.