Laser Microirradiation of Chinese Hamster Cells at Wavelength 365 nm

Cells of a V79 subline of the Chinese hamster were microirradiated at wavelength 365 nm in the presence of the psoralen derivative, trioxsalen. Microirradiation was accomplished by a pulsed argon laser microbeam either in anaphase or in interphase 3 hr after mitosis. Inhibition of clonal growth and formation of micronuclei at the first postirradiation mitosis were observed after microirradiation of anaphase chromosomes and of small parts of the interphase nucleus. Microirradiation of the cytoplasm beside the interphase nucleus or between the sets of chromosomes moving apart from each other in anaphase did not produce these effects. Anaphase experiments showed that only the daughter cell which received microirradiated chromatin exhibited an abnormal growth pattern. Most interestingly, shattering of the whole chromosome complement could be induced by microirradiation of small parts of the interphase nucleus and post-treatment with caffeine. Since microirradiation of chromatin in the absence of psoralen was not effective, we consider formation of psoralen photoadducts to nucleic acids in microirradiated chromatin to be the specific cause of the effects. We suggest that DNA photolesions in chromosome segments present in the microirradiated part of the nucleus can induce shattering of all the chromosomes in the microirradiated nucleus. Several possibilities are discussed to explain this unexpected finding

Near-optimal asymmetric binary matrix partitions

We study the asymmetric binary matrix partition problem that was recently introduced by Alon et al. (WINE 2013) to model the impact of asymmetric information on the revenue of the seller in take-it-or-leave-it sales. Instances of the problem consist of an $n \times m$ binary matrix $A$ and a probability distribution over its columns. A partition scheme $B=(B_1,...,B_n)$ consists of a partition $B_i$ for each row $i$ of $A$. The partition $B_i$ acts as a smoothing operator on row $i$ that distributes the expected value of each partition subset proportionally to all its entries. Given a scheme $B$ that induces a smooth matrix $A^B$, the partition value is the expected maximum column entry of $A^B$. The objective is to find a partition scheme such that the resulting partition value is maximized. We present a $9/10$-approximation algorithm for the case where the probability distribution is uniform and a $(1-1/e)$-approximation algorithm for non-uniform distributions, significantly improving results of Alon et al. Although our first algorithm is combinatorial (and very simple), the analysis is based on linear programming and duality arguments. In our second result we exploit a nice relation of the problem to submodular welfare maximization.Comment: 17 page

Using self-definition to predict the influence of procedural justice on organizational, interpersonal, and job/task-oriented citizenship behaviors

An integrative self-definition model is proposed to improve our understanding of how procedural justice affects different outcome modalities in organizational behavior. Specifically, it is examined whether the strength of different levels of self-definition (collective, relational, and individual) each uniquely interact with procedural justice to predict organizational, interpersonal, and job/task-oriented citizenship behaviors, respectively. Results from experimental and (both single and multisource) field data consistently revealed stronger procedural justice effects (1) on organizational-oriented citizenship behavior among those who define themselves strongly in terms of organizational characteristics, (2) on interpersonal-oriented citizenship behavior among those who define themselves strongly in terms of their interpersonal relationships, and (3) on job/task-oriented citizenship behavior among those who define themselves weakly in terms of their distinctiveness or uniqueness. We discuss the relevance of these results with respect to how employees can be motivated most effectively in organizational settings

Images of psychiatry and psychiatrists

Peer reviewedPublisher PD

Rapid generation of chromosome-specific alphoid DNA probes using the polymerase chain reaction

Non-isotopic in situ hybridization of chromosome-specific alphoid DNA probes has become a potent tool in the study of numerical aberrations of specific human chromosomes at all stages of the cell cycle. In this paper, we describe approaches for the rapid generation of such probes using the polymerase chain reaction (PCR), and demonstrate their chromosome specificity by fluorescence in situ hybridization to normal human metaphase spreads and interphase nuclei. Oligonucleotide primers for conserved regions of the alpha satellite monomer were used to generate chromosome-specific DNA probes from somatic hybrid cells containing various human chromosomes, and from DNA libraries from sorted human chromosomes. Oligonucleotide primers for chromosome-specific regions of the alpha satellite monomer were used to generate specific DNA probes for the pericentromeric heterochromatin of human chromosomes 1, 6, 7, 17 and X directly from human genomic DNA

Evolutionary game theory in growing populations

Existing theoretical models of evolution focus on the relative fitness advantages of different mutants in a population while the dynamic behavior of the population size is mostly left unconsidered. We here present a generic stochastic model which combines the growth dynamics of the population and its internal evolution. Our model thereby accounts for the fact that both evolutionary and growth dynamics are based on individual reproduction events and hence are highly coupled and stochastic in nature. We exemplify our approach by studying the dilemma of cooperation in growing populations and show that genuinely stochastic events can ease the dilemma by leading to a transient but robust increase in cooperationComment: 4 pages, 2 figures and 2 pages supplementary informatio

Stereospecific thionation of 2-ethoxy-1,2-oxaphosphorinane 2-oxide and its derivatives with Lawesson's reagent

The parent phostone, 2-ethoxy-1,2-oxaphosphorinane 2-oxide 1, and derivatives with substituents at the 3-position (methyl, phenyl, and benzyl; compounds 2-4) were convened with Lawesson's reagent to provide the corresponding sulfide analogues 5-8 in moderate yields. The conversion of 2-4 occurred with retention of configuration at the phosphorus center. This was implied from the relative R(f) values and 13C and 31P NMR chemical shifts of the individual isomers and confirmed for the transformation of 3b to 7b by X-ray structures of each of these. Oxidation of 7b, 8a, and 8b with m-chloroperoxybenzoic acid alone led to the corresponding oxides 3b, 4a, and 4b with retention. The presence of trifluoroacetic acid during this oxidation process led to varying degrees of epimerization about phosphorus and was dependent on the relative molar equivalents of this acid

5-Benzoyl-2-(1H-indol-3-yl)-4-(4-methyl­phen­yl)-4,5-dihydro­furan-3-carbonitrile

The furan ring in the title compound, C27H20N2O2, adopts a twisted conformation about the sp 3—sp 3 bond. The mol­ecular structure is stabilized by an intra­molecular C—H⋯O inter­action which generates an S(6) ring motif. The crystal packing is stabilized by N—H⋯O and C—H⋯O inter­actions generating centrosymmetric R 2 2(18) and C(6) chain motifs, respectively. A weak C—H⋯π inter­action is also observed

4-(4-Chloro­phen­yl)-4-hy­droxy­piperidinium benzoate

In the title salt, C11H15ClNO+·C7H5O2 −, the dihedral angle between the mean planes of the chloro­phenyl ring of the cation and the benzene ring of the anion is 74.4 (1)°. In the cation, the six-membered piperazine ring adopts a chair conformation. The crystal packing is stabilized by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds, and weak inter­molecular C—H⋯O, C—H⋯Cl and C—H⋯π inter­actions

The edge of neutral evolution in social dilemmas

The functioning of animal as well as human societies fundamentally relies on cooperation. Yet, defection is often favorable for the selfish individual, and social dilemmas arise. Selection by individuals' fitness, usually the basic driving force of evolution, quickly eliminates cooperators. However, evolution is also governed by fluctuations that can be of greater importance than fitness differences, and can render evolution effectively neutral. Here, we investigate the effects of selection versus fluctuations in social dilemmas. By studying the mean extinction times of cooperators and defectors, a variable sensitive to fluctuations, we are able to identify and quantify an emerging 'edge of neutral evolution' that delineates regimes of neutral and Darwinian evolution. Our results reveal that cooperation is significantly maintained in the neutral regimes. In contrast, the classical predictions of evolutionary game theory, where defectors beat cooperators, are recovered in the Darwinian regimes. Our studies demonstrate that fluctuations can provide a surprisingly simple way to partly resolve social dilemmas. Our methods are generally applicable to estimate the role of random drift in evolutionary dynamics.Comment: 17 pages, 4 figure