Precocious activation of APC/C-Cdh1 at pre-anaphase causes genome instability

Faithful chromosome segregation and thereby accurate gene transmission are crucial for all organisms. Until proper attachment of the mitotic spindle to the kinetochore is established, the ubiquitin ligase (E3) Cdc20-activated APC/C (anaphase promoting complex/cyclosome) is repressed by the spindle assembly checkpoint (SAC) and sister chromatin cohesion is protected. Mutants defective in SAC fail to arrest at metaphase even in the presence of damaged microtubules. Interestingly, a similar phenomenon occurs in yeast cells defective in Bub2, a negative factor of the mitotic exit network (MEN), which is required for telophase onset, although its precise molecular mechanism is unknown. Here, we show that chromosome missegregation occurs frequently in bub2∆ cells in the presence of damaged microtubules. The loss of Bub2 caused precocious activation of APC/C-Cdh1/Hct1 at pre-anaphase, leading to securin degradation and then separase-mediated cohesin cleavage. Overexpression of CDH1 and CDC14, encoding Cdc14 phosphatase, at pre-anaphase similarly caused chromosome missegregation. Thus, sequential activation of APC/C-Cdc20 and then APC/C-Cdh1 is critical for precise chromosome segregation and precocious activation of APC/C-Cdh1 at pre-anaphase causes genomic instability. Since degradation of human securin is also mediated by APC/C-Cdc20 and APC/C-Cdh1, this study predicts that precocious activation APC/C-Cdh1 in human cells similarly causes genomic instability, and thereby cell death or tumorigenesis

Generalized Riesz Projections and Toeplitz Operators

Let 1 < p < ∞ . In this paper, for a measurable function v and a weight function w, the generalized Riesz projection P v is defined by P vf = vP(v -1f). (f ∈ L p(w)). If P0 is the self-adjoint projection from L2 (w) onto H2 (w), then P0 = P α for some outer function α satisfying w = |α| -2 . In this paper, P v on L p (w) is studied. As an application, the invertibility criterion for the generalized Toeplitz operator Tφv and the generalized singular integral operator φPv+Qv, Qv = I - Pv are investigated using the weighted norm inequality. The operator norm inequality for the generalized Hankel operator Hφv is also presented

Is the Comet Assay a Sensitive Procedure for Detecting Genotoxicity?

Although the Comet assay, a procedure for quantitating DNA damage in mammalian cells, is considered sensitive, it has never been ascertained that its sensitivity is higher than the sensitivity of other genotoxicity assays in mammalian cells. To determine whether the power of the Comet assay to detect a low level of genotoxic potential is superior to those of other genotoxicity assays in mammalian cells, we compared the results of Comet assay with those of micronucleus test (MN test). WTK1 human lymphoblastoid cells were exposed to methyl nitrosourea (MNU), ethyl nitrosourea (ENU), methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), bleomycin (BLM), or UVC. In Comet assay, cells were exposed to each mutagen with (Comet assay/araC) and without (Comet assay) DNA repair inhibitors (araC and hydroxyurea). Furthermore, acellular Comet assay (acellular assay) was performed to determine how single-strand breaks (SSBs) as the initial damage contributes to DNA migration and/or to micronucleus formation. The lowest genotoxic dose (LGD), which is defined as the lowest dose at which each mutagen causes a positive response on each genotoxicity assay, was used to compare the power of the Comet assay to detect a low level of genotoxic potential and that of MN test; that is, a low LGD indicates a high power. Results are summarized as follows: (1) for all mutagens studied, LGDs were MN test ≦ Comet assay; (2) except for BLM, LGDs were Comet assay/araC ≦ MN test; (3) except for UVC and MNU, LGDs were acellular assay ≦ Comet assay/araC ≦ MN test ≦ Comet assay. The following is suggested by the present findings: (1) LGD in the Comet assay is higher than that in MN test, which suggests that the power of the MN test to detect a low level of genotoxic potential is superior to that of the Comet assay; (2) for the studied mutagens, all assays were able to detect all mutagens correctly, which suggests that the sensitivity of the Comet assay and that of the MN test were exactly identical; (3) the power of the Comet assay to detect a low level of genotoxic potential can be elevated to a level higher than that of MN test by using DNA resynthesis inhibitors, such as araC and HU

Characteristics of Novel Triplet Spun Yarns Made from Fibers of Differing Fineness

In order to reduce the hairiness of ring spun yarns and to develop novel multilayered spun yarns, we investigated the properties of triplet spun yams made from the same size of three rovings with different fiber fineness using an experimental ring spinning frame. The results were: (1) different fiber fineness triplet spun yarn, a new yarn made by combination staple fibers of three different fineness into one twisting process; (2) although triplet spun yarn had a side-by-side structure in the cross-section, the central angle made by the assembly of finer fibers was smaller than that of coarser fibers; and (3) in comparison with single yam, triplet spun yarn had less hairiness and greater strength because of the lower spinning tension of each strand and the twist propagation in each strand.ArticleTEXTILE RESEARCH JOURNAL. 79(10):947-952 (2009)journal articl

Pemphigus Vulgaris Confined to the Gingiva: A Case Report

Pemphigus Vulgaris (PV) is an autoimmune intraepithelial blistering disease involving the skin and mucous membranes. Oral mucosa is frequently affected in patients with PV, and oral lesions may be the first sign of the disease in majority of patients. In some patients, oral lesions may also be followed by skin involvement. Therefore, timely recognition and therapy of oral lesions is critical as it may prevent skin involvement. Early oral lesions of PV are, however, often regarded as difficult to diagnose, since the initial oral lesions may be relatively nonspecific, manifesting as superficial erosions or ulcerations, and rarely presenting with the formation of intact bullae. Lesions may occur anywhere on the oral mucosa including gingiva; however; desquamtive gingivitis is less common with PV than other mucocutaneous conditions such as pemphigoid or lichen planus. This paper describes the case of a patient presenting with a one-year history of painful gingival, who is finally diagnosed as having PV

Microscopic photometry and its parameterization for objective evaluation of aesthetics of woven fabrics

One of the most important end-use performance parameters for fabrics and other textile products are the fabric hands and fabric aesthetics. Our previous research attempted to elucidate the factors that affect the fabric aesthetics using factor analysis and identified two principal factors tentatively labelled as 'lustre and depth sensation' and 'surface roughness sensation'. The focus of the second step in the study of fabric aesthetics is on the investigation of the objective trends in the performance evaluation of textiles. In this study, we developed our own experimental equipment based on microscopic goniophotometric principles and its parameterization method. Subsequently, we attempted to define an index based on the distribution of the reflection intensity of woven fabrics and its characterization in order to evaluate the principal factors governing fabric aesthetics. On the basis of the results, we infer that microscopic goniophotometry and its parameterization is a more viable approach than conventional macroscopic goniophotometry for the quantitative evaluation of the principal factors governing fabric aesthetics.ArticleTEXTILE RESEARCH JOURNAL. 82(19):1982-1995 (2012)journal articl