Ring cleavage occurred when 1,2,4-triazino-1,2,4-triazines (3), (4) and (5) were treated with concentrated hydrochloric acid to yield N-substituted triazines (7) and (8). These confirm the given configuration assigned to the isomeric triazinotriazines. 6-Methyl-2-phenyl-7H-oxazolo [3,2-b][1,2,4]-triazin-7-one (9) underwent ring cleavage on treatment with sodium alkoxide to afford 3-alkoxy-1...

some of the most important characters in convenience are economic, social equity and optimal distribution of facilities of development among people in societies. planners are, in different societies in direction for decreasing inequity and poverty, designing many plans. fundamental steps in design' planning for capturing these goals is paying more attention to plans with an approach to rea...

DNA can be concatenated by hybridization of DNA fragments with protruding single-stranded termini. DNA cleavage occurring at a nucleotide containing a DNA base analogue is a useful method to obtain DNA with designed protruding termini. Here, we report a novel non-enzymatic DNA cleavage reaction for DNA concatenation. We found that DNA is cleaved at a nucleotide containing 5-ethynyluracil in a m...

Experimental studies on the cleavage of various RNA molecules--poly(U), 3',5''-UpU, 2',5''-UpU, and 3',5''-ApA--catalyzed by imidazole buffers show that there is a sequential bifunctional mechanism. One catalyst species converts the substrate to an intermediate phosphorane, and the second catalyst converts the phosphorane to cleavage products. Detailed steady-state kinetics are presented to det...

In fertilized eggs of Xenopus laevis a marked flattening of the pigmented animal hemisphere has been observed. The flattening begins 15-20 minutes before the appearance of the cleavage furrow. As the furrow develops, the pigmented surface relaxes and rounds up. The initial appearance of the furrow is thus shown to be a combination of furrow deepening and rounding up of adjacent pigmented surfac...

I-SceI is a homing endonuclease that specifically cleaves an 18-bp double-stranded DNA. I-SceI exhibits a strong preference for cleaving the bottom strand DNA. The published structure of I-SceI bound to an uncleaved DNA substrate provided a mechanism for bottom strand cleavage but not for top strand cleavage. To more fully elucidate the I-SceI catalytic mechanism, we determined the X-ray struct...

We developed several novel tools to genome wide screen for CNVs and SNPs in single cells. When applied to cleavage stage embryos from young fertile couples we discovered, unexpectedly, an extremely high incidence of chromosomal instability, a hallmark of tumorigenesis (Vanneste et al., Nature Medicine, 2009; Vanneste et al., Hum.Reprod., 2011). Not only mosaicisms for whole chromosome aneuploid...

Background: Parthenogenetic activation is a possible way to produce homogeneous embryos with the some ploidy. Probably such embryos could be used in other areas of biotechnology. Calcium signals are known as important regulators of oocyte activation. Extracellular calcium is required for initiation of meiotic resumption and development. Calcium ionophore A23187 is known to elevate intracellular...

a study was conducted to investigate the effect of follicular size (small,

the zinc(ii) complex [zn2(dmdtc)2(μ-dmdtc)2] has been synthesized directly from thiram ligand, containing a disulfide bond {dmdtc = n,n-dimethyldithiocarbamate; thiram = n,n-tetramethylthiuram disulfide}, and characterized by elemental analysis and spectroscopic methods. surprisingly thiram, undergoes a reductive disulfide bond scission upon reaction with zn2+ in methanolic media to give the [z...