Cytotoxicity of new cytochalasans fromChaetomium globosum

Zusammenfassung Nachweis, dass CHCl₃-Rohextrakte aus Myzelien und Filtraten der Zuchtmedien vonChaetomium globosum Kunze ex Fries einen akuten toxischen Effect auf HeLa-Zellen in vitro, sowie auf Mäuse zeigten. Chaetoglobosine die aus Mycelium-Rohextrakt isoliert wurden und chemisch zu den Cytochalasanen gehören, induzierten in HeLa-Zellen eine Polynukleierung und multipolare Kernverteilung. Auch beim Chaetogobosin wird eine Mikrofilament-Schädigung angenommen.     

Increased proliferation of B cells and auto-immunity in mice lacking protein kinase Cdelta

Protein kinase C (PKC), which comprises 11 closely related isoforms, has been implicated in a wide variety of cellular processes, such as growth, differentiation, secretion, apoptosis and tumour development. Among the PKC isotypes, PKC-delta is unique in that its overexpression results in inhibition of cell growth. Here we show that mice that lack PKC-delta exhibit expansion of the B-lymphocyte population with the formation of numerous germinal centres in the absence of stimulation. The rate of proliferation in response to stimulation was greater for B cells from PKC-delta-deficient mice than for those from wild-type mice. Adoptive transfer experiments suggested that the hyperproliferation phenotype is B-cell autonomous. Production of interleukin-6 was markedly increased in B cells of PKC-delta-null mice as a result of an increase in the DNA-binding activity of NF-IL6. Furthermore, the PKC-delta-deficient mice contain circulating autoreactive antibodies and display immune-complex-type glomerulonephritis, as well as lymphocyte infiltration in many organs. These results suggest that PKC-delta has an indispensable function in negative regulation of B-cell proliferation, and is particularly important for the establishment of B-cell tolerance.     

First-generation black-hole-forming supernovae and the metal abundance pattern of a very iron-poor star

It has been proposed theoretically that the first generation of stars in the Universe (population III) would be as massive as 100 solar masses (100 M(O)), because of inefficient cooling of the precursor gas clouds. Recently, the most iron-deficient (but still carbon-rich) low-mass star--HE0107-5240--was discovered. If this is a population III star that gained its metals (elements heavier than helium) after its formation, it would challenge the theoretical picture of the formation of the first stars. Here we report that the patterns of elemental abundance in HE0107-5240 (and other extremely metal-poor stars) are in good accord with the nucleosynthesis that occurs in stars with masses of 20-130 M(O) when they become supernovae if, during the explosions, the ejecta undergo substantial mixing and fallback to form massive black holes. Such supernovae have been observed. The abundance patterns are not, however, consistent with enrichment by supernovae from stars in the range 130-300 M(O). We accordingly infer that the first-generation supernovae came mostly from explosions of approximately 20-130 M(O) stars; some of these produced iron-poor but carbon- and oxygen-rich ejecta. Low-mass second-generation stars, like HE0107-5240, could form because the carbon and oxygen provided pathways for the gas to cool.     

氮杂磷烯化合物的合成及31PNMR表征

通过相应膦二氯化物与２,４,６－三叔丁基苯基氨基锂的反应,再经１,８－二氮双环「５．４．０」－７－十一烯脱氯化氢合成了两个新的氮杂磷烯化合物。与二磷烯比较,分析了它们在核磁共振磷谱中化学位移的变化。     

Calcium-dependent phospholipid scrambling by TMEM16F

In all animal cells, phospholipids are asymmetrically distributed between the outer and inner leaflets of the plasma membrane. This asymmetrical phospholipid distribution is disrupted in various biological systems. For example, when blood platelets are activated, they expose phosphatidylserine (PtdSer) to trigger the clotting system. The PtdSer exposure is believed to be mediated by Ca(2+)-dependent phospholipid scramblases that transport phospholipids bidirectionally, but its molecular mechanism is still unknown. Here we show that TMEM16F (transmembrane protein 16F) is an essential component for the Ca(2+)-dependent exposure of PtdSer on the cell surface. When a mouse B-cell line, Ba/F3, was treated with a Ca(2+) ionophore under low-Ca(2+) conditions, it reversibly exposed PtdSer. Using this property, we established a Ba/F3 subline that strongly exposed PtdSer by repetitive fluorescence-activated cell sorting. A complementary DNA library was constructed from the subline, and a cDNA that caused Ba/F3 to expose PtdSer spontaneously was identified by expression cloning. The cDNA encoded a constitutively active mutant of TMEM16F, a protein with eight transmembrane segments. Wild-type TMEM16F was localized on the plasma membrane and conferred Ca(2+)-dependent scrambling of phospholipids. A patient with Scott syndrome, which results from a defect in phospholipid scrambling activity, was found to carry a mutation at a splice-acceptor site of the gene encoding TMEM16F, causing the premature termination of the protein.     

基于小波变换的分形随机信号希尔伯特变换的波形估计

非平稳1/f类分形随机过程是一类重要的弱自相似随机过程,其典型例子是分形布朗运动,作者考察了弱自相似过程的希尔伯特变换,证明了希尔伯特变换具有弱自相似不变性,进而利用分形布朗运动的希尔伯特变换BH（t)小波系数能量向低频集中的特性,采用最优门限方法实现BH（t)的波形估计。     

Data model transformation in CAD system for multi-view modeling

This paper describes multi-view modeling and data model transformation for the modeling. We have proposed a reference model of CAD system generation, which can be applied to various domain-specific languages. However, the current CAD system generation cannot integrate data of multiple domains. Generally each domain has its own view of products. For example, in the domain of architectural structure, designers extract the necessary data from the data in architecture design. Domain experts translate one view into another view beyond domains using their own brains. The multi-view modeling is a way to integrate product data of multiple domains, and make it possible to translate views among various domains by computers.     

Mutations affecting components of the SWI/SNF complex cause Coffin-Siris syndrome

By exome sequencing, we found de novo SMARCB1 mutations in two of five individuals with typical Coffin-Siris syndrome (CSS), a rare autosomal dominant anomaly syndrome. As SMARCB1 encodes a subunit of the SWItch/Sucrose NonFermenting (SWI/SNF) complex, we screened 15 other genes encoding subunits of this complex in 23 individuals with CSS. Twenty affected individuals (87%) each had a germline mutation in one of six SWI/SNF subunit genes, including SMARCB1, SMARCA4, SMARCA2, SMARCE1, ARID1A and ARID1B.     

Phytochemistry: structure of the blue cornflower pigment

The same anthocyanin pigment makes roses red but cornflowers blue, a phenomenon that has so far not been entirely explained. Here we describe the X-ray crystal structure of the cornflower pigment, which reveals that its blue colour arises from a complex of six molecules each of anthocyanin and flavone, with one ferric iron, one magnesium and two calcium ions. We believe that this tetrametal complex may represent a previously undiscovered type of supermolecular pigment.