EML4 promotes the loading of NUDC to the spindle for mitotic progression

Echinoderm microtubule-associated protein (EMAP)-like (EML) family proteins are microtubule-associated proteins that have a conserved hydrophobic EMAP-like protein (HELP) domain and multiple WD40 domains. In this study, we examined the role of EML4, which is a member of the EML family, in cell division. Time-lapse microscopy analysis demonstrated that EML4 depletion induced chromosome misalignment during metaphase and delayed anaphase initiation. Further analysis by immunofluorescence showed that EML4 was required for the organization of the mitotic spindle and for the proper attachment of kinetochores to microtubules. We searched for EML4-associating proteins by mass spectrometry analysis and found that the nuclear distribution gene C (NUDC) protein, which is a critical factor for the progression of mitosis, was associated with EML4. This interaction was mediated by the WD40 repeat of EML4 and by the C-terminus of NUDC. In the absence of EML4, NUDC was no longer able to localize to the mitotic spindle, whereas NUDC was dispensable for EML4 localization. Our results show that EML4 is critical for the loading of NUDC onto the mitotic spindle for mitotic progression.     

Carbazole and arylamine functionalized iridium complexes for efficient electro-phosphorescent light-emitting diodes

We report the synthesis and characterization of four cyclometalated iridium complexes based on carbazole and arylamine modified 2-phenylpyridine. The carbazole and arylamine groups are linked to 2-phenyl pyridine backbone to enhance the energy harvesting and transfer from host to guest materials. The electrochemical and photophysical properties of the complexes are studied and electroluminescent devices are fabricated. The results show that the complexes with ligands containing carbazole moieties have desirable phosphorescent properties. The device with complex 3 doped PVK (poly (vinylcarbazole)) as emission layer achieves maximum luminous efficiency of 6.56 cd A⁻¹ and maximum brightness of 14448 cd m⁻².     

Chromosomal characteristics of ribosomal DNA in two extant species of North American mudminnows Umbra pygmaea and U. limi (Euteleostei: Umbridae)

The locations and chromosomal characteristics of ribosomal DNA (rDNA) sites in the karyotypes of two extant North American species of mudminnows, Umbra pygmaea and U. limi (2n = 22, NF = 44), were analyzed sequentially by conventional Giemsa staining, Ag staining, CMA(3) fluorescence and fluorescence in situ hybridization (FISH). The nucleolar organizer regions (NORs) were located in the fourth chromosomal pair in both species (pericentromeric region in U. pygmaea and subtelomeric in U. LIMI). These sites were strongly CMA(3)-positive suggesting that the rDNA sites in these species are associated with GC-rich DNA. FISH with a rDNA probe gave consistently positive signals in the same regions detected by Ag-staining and CMA(3)-fluorescence. However, both species also had additional CMA(3)-positive/Ag-negative heterochromatic blocks at pericentrometric regions of several chromosomal pairs (three in U. pygmaea and five in U. limi). FISH revealed additional rDNA clusters in both species. It is hypothesized that a paracentric inversion of the chromosome arm carrying the NORs might be one of the rearrangements differentiating the karyotypes of two North American species. The presence of additional rDNA sites is indicative of more complex rearrangements. The pericentromeric NOR phenotype of Umbra pygmaea is similar to that seen in U. krameri and in the distantly related genus Esox.     

有害疣孢霉Hypomyces perniciosus遗传转化体系的建立及其突变体库的构建

有害疣孢霉Hypomyces perniciosus是引起双孢蘑菇Agaricus bisporus湿泡病的病原真菌,目前其致病分子机理尚不清楚,而高效稳定的遗传转化体系和突变体库构建是挖掘和研究病原菌致病基因的基础和有效手段。因此,本实验以高致病力的有害疣孢霉菌株WH001为研究对象,采用冻融法将双元载体pBHt1转入农杆菌AGL-1中,建立并优化根癌农杆菌介导的遗传转化体系,并利用其构建T-DNA插入突变体库。结果表明有害疣孢霉菌株WH001的潮霉素（Hygromycin,Hyg）耐受浓度为250ng/L,当农杆菌侵染液浓度OD₆₀₀=1,侵染时间为30min,乙酰丁香酮（Acetosyringone,AS）浓度为1.5mg/mL,共培养时间为3d时,转化体系效率最高。然后利用该优化体系构建有害疣孢霉的突变体库,通过PCR检测和形态学鉴定获得若干表型发生改变、稳定遗传的T-DNA插入突变体,与原菌种WH001相比,突变体在菌丝形态、生长速率、色素分泌和致病力等方面发生改变。本研究为进一步挖掘有害疣孢霉未知基因功能、解析生物学性状、探讨致病分子机制奠定基础。     

Trends in single trait dispersion between early-mid successional stages: the importance of species pool extension and habitat scale

Aims Are there trends of increasing/decreasing dispersion of single, categorical traits related to early/late-successional species between stages of community development? If yes, are these trends dependent on species pool extension and habitat scale? Is there a consistent reduction in single trait convergence or divergence in any seral stage when scaling down from ecological to local species pool?Methods Presence of all vascular species rooted within plots of 5 × 5 m was recorded in assemblages of exposed mining spoils (EMS) and heathlands (HTL), which form a chronosequence on two abandoned ore tailing heaps located close to each other in the south-eastern Carpathians (Romania). Fifteen nominal, trait attributes of plant species co-occurring in the two seral assemblages were collected from available databases and subsequently classified as either successionally 'pioneer' or 'mature'. The strength of single trait convergence or divergence was estimated by comparison with null plant assemblages at patch type (meta-community) level by reference to the ecological or local species pool, and at community level.Important findings At patch type level, all pioneer and mature trait attributes (apart from short life span), with significant variation between the two seral stages, increased and, respectively, decreased in dispersion irrespective of species pool extension. However, these trends were more conspicuous when using the ecological species pool, very likely due to relaxation in abiotic filtering and dispersal limitation. At community level, no consistent trends were observed between EMS and HTL assemblages, probably because most trait attributes were sorted by microenvironmental filters displaying high variation, like topography or habitat patch geometry. In both seral stages, there was a general weakening of trait convergence or divergence at patch type level when scaling down from the ecological to the local species pool, which was due to niche space contraction. At community level, there was a trend of rise in dispersion of pioneer attributes along the observed chronosequence, presumably imputable to increasing competition for light and underground water, but an opposite trend of dispersion drop in mature attributes was not so evident. Based on these findings, we proposed two rules of thumb concerning the expected changes in dispersion of trait attributes at patch level along successions and between levels of species pool extension. In conclusion, trends in the successional dynamics of pioneer and mature trait dispersion are clearly detectable at meta-community level, especially by reference to the ecological species pool. Habitat scale and species pool extension are key factors to consider and report when estimating the magnitude of single trait dispersion.     

Novel subunit in C4b-binding protein required for protein S binding

C4b-binding protein (C4BP) is a multimeric protein with regulatory functions in the complement system. It also interacts with vitamin K-dependent protein S, which is involved in the regulation of the coagulation system. It has been demonstrated that C4BP consists of seven disulfide-linked, identical 70-kDa subunits, which are arranged to give the molecule a spider-like structure. We now have evidence for the presence of a new subunit in C4BP. On sodium dodecyl sulfate-poly-acrylamide gel electrophoresis it appears as a weakly stainable band with a molecular weight of approximately 45,000. The subunit was isolated by gel filtration in 6 M guanidine hydrochloride of reduced and carboxymethylated C4BP. Its amino-terminal sequence is distinct from previously known protein sequences. The stoichiometry of 45- to 70-kDa subunits was estimated to be 1:9, indicating the presence of one 45-kDa subunit per C4BP molecule. The new subunit was demonstrated to be a disulfide-linked component of the central core of C4BP. It was sensitive to proteolysis by chymotrypsin, and when cleaved the protein S binding ability of C4BP was lost. With protein S bound to C4BP, the 45-kDa subunit was protected from degradation by chymotrypsin, and the protein S binding site remained intact. These data suggest that the new subunit is directly involved in protein S binding.