Three-dimensional ultrastructural analysis of the Saccharomyces cerevisiae mitotic spindle

The three dimensional organization of microtubules in mitotic spindles of the yeast Saccharomyces cerevisiae has been determined by computer-aided reconstruction from electron micrographs of serially cross-sectioned spindles. Fifteen spindles ranging in length from 0.6-9.4 microns have been analyzed. Ordered microtubule packing is absent in spindles up to 0.8 micron, but the total number of microtubules is sufficient to allow one microtubule per kinetochore with a few additional microtubules that may form an interpolar spindle. An obvious bundle of about eight interpolar microtubules was found in spindles 1.3-1.6 microns long, and we suggest that the approximately 32 remaining microtubules act as kinetochore fibers. The relative lengths of the microtubules in these spindles suggest that they may be in an early stage of anaphase, even though these spindles are all situated in the mother cell, not in the isthmus between mother and bud. None of the reconstructed spindles exhibited the uniform populations of kinetochore microtubules characteristic of metaphase. Long spindles (2.7-9.4 microns), presumably in anaphase B, contained short remnants of a few presumed kinetochore microtubules clustered near the poles and a few long microtubules extending from each pole toward the spindle midplane, where they interdigitated with their counterparts from the other pole. Interpretation of these reconstructed spindles offers some insights into the mechanisms of mitosis in this yeast.     

Synthesis of multifunctional surfactants for elaboration of micellar model systems of enzymes

In order to provide a closer analogy between micelles and enzymes, the design of functionalized micellar systems have been undertaken. This paper presents the synthesis of surfactant cationic molecules which contains either a free or a protected aldehyde group. An ammonium quaternary surfactant with two functional groups, aldehyde dimethyl acetal and imidazole, has also been synthesized.     

Burden of self-care in seriously ill patients: Impact on adjustment.

Perceived, but not actual, control over treatment has been consistently related to better adjustment in chronic illness. This study examined the relationship between actual control over treatment and severity of illness and their influence on depression in a chronically ill population of end-stage renal disease (ESRD) patients. The authors hypothesized that as severity of illness increases, the burden of control over treatment would increase depression. Severity of illness and depression was assessed for 98 ESRD patients. Control over treatment was represented by whether dialysis patients were self-administering treatment (high control) or were receiving treatment from the medical staff (low control). Results indicated that for the most severely ill patients, high control over treatment resulted in poorer adjustment. Furthermore, this effect was due in part to how illness interferes with social relationships in seriously ill, self-care patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Porcine spleen deoxyribonuclease II. Covalent structure, cDNA sequence, molecular cloning, and gene expression

Porcine spleen DNase II, a lysosomal acid hydrolase, is a noncovalently linked alpha.beta heterodimer (Liao, T.-H. (1985) J. Biol. Chem. 260, 10708-10713). The alpha subunit, after disulfide cleavage, yields two chains, alpha1 and alpha2. The complete amino acid sequences of the alpha1, beta, and alpha2 chains were elucidated by protein sequencing, and the pairings of one interchain disulfide between alpha1 and alpha2 and of three intrachain disulfides in alpha2 were assigned. Six carbohydrate attachment sites, two in beta and four in alpha2, were detected by sugar analyses. The cDNA of DNase II was amplified using primers synthesized on the basis of the amino acid sequences determined. The amplified fragments shown to be a cDNA sequence of 1,292 bases. This cDNA sequence has an open reading frame encoding a 364-amino acid polypeptide containing a putative transmembrane peptide at the NH2-end, two small connecting peptides in the middle, and a peptide at the COOH terminus. These are evidently removed to form mature DNase II. Thus, all three chains in the sequence alpha1, beta, and alpha2 are coded by the same cDNA. When Chinese hamster ovary cells were transfected with a cloned plasmid with an inserted cDNA fragment encoding the entire reading frame, the expressed protein was released into the growth medium as an active form of DNase II.     

Application of the Extended Corresponding States Method to the Calculation of the Ammonia–Water Mixture Thermodynamic Surface

The paper presents an application of the one-fluid extended corresponding states method to the calculation of the thermodynamic surface of the ammonia–water mixture. Each pure component of the mixture is considered as a reference fluid, and to test the behavior of the model in wide ranges of temperature and pressure, the Haar–Gallagher and the Pruß–Wagner equations of state were chosen for pure ammonia and water, respectively. To avoid numerical problems during the calculation of the pure-component equivalent substance reducing ratios (or scaling factors), a method based on the mapping defined by the extended corresponding states algorithm and two-dimensional interpolation is proposed. The estimation of the binary interaction parameters was performed using the general case of the least squares method, i.e., the case when all measurements (observations) and unknowns are subject to uncertainty and are adjusted simultaneously with the constraint equations. The results show a strong temperature and composition dependence of both interaction parameters for the liquid, as well as for the vapor phase. A formulation for the binary interaction parameters as continuous functions of these variables was also derived and optimized using the structural optimization and regression analysis. The final statistical quality of the approach presented in the paper was assessed using the available data on thermophysical properties of the mixture.     

The effect of air exposure on the photocurrent in a conjugated platinum poly-yne

We present photocurrent spectra of an ITO/Pt-poly-yne/Al photocell under vacuum after annealing and also after exposure to air. We find that air enhances exciton dissociation. We also find that a low energy photocurrent tail appears after exposure of the cell to air. The enhancement of the photovoltaic response to air is found to be reversible after annealing under vacuum.     

The LMO1 and LDB1 proteins interact in human T cell acute leukaemia with the chromosomal translocation t(11;14)(p15;q11)

The ectopic expression of LMO1 or LMO2 in T cell acute leukaemias resulting from chromosomal translocations t(11;14)(p15;qll) or t(11;14)(p13;q11) respectively in a causal factor in tumorigenesis. LMO1 has been found as a heterodimer with a 46 Kd protein in a T cell line derived from a childhood T-acute leukaemia. This 46 Kd protein is the LIM-binding protein LDB1/NLI. The latter is a phosphoprotein and binds to LMO1 in its phosphorylated state and essentially all the LMO1 and LDB1 protein in the T cell line is part of the complex. Therefore, the LMO1-LDB1 interaction is likely to be involved in tumorigenesis after LMO1 is ectopically expressed following chromosomal translocation in T cells prior to development of acute leukaemias.