Tactical Voting in Plurality Elections

How often will elections end in landslides? What is the probability for a head-to-head race? Analyzing ballot results from several large countries rather anomalous and yet unexplained distributions have been observed. We identify tactical voting as the driving ingredient for the anomalies and introduce a model to study its effect on plurality elections, characterized by the relative strength of the feedback from polls and the pairwise interaction between individuals in the society. With this model it becomes possible to explain the polarization of votes between two candidates, understand the small margin of victories frequently observed for different elections, and analyze the polls'' impact in American, Canadian, and Brazilian ballots. Moreover, the model reproduces, quantitatively, the distribution of votes obtained in the Brazilian mayor elections with two, three, and four candidates.     

Identification of UDP-linked murein precursors as contaminants in recombinant proteins of low molecular weight.

The A(280)/A(260) ratio of a purified protein is frequently used as an indication of the purity of the preparation with respect to nucleic acids. We show here that for low-molecular-weight recombinant proteins purified from Escherichia coli, a low A(280)/A(260) ratio can also result from contamination with UDP-linked murein precursors derived from bacterial cell wall metabolism. Although these precursors are small molecules of molecular weight 1000-1200, they comigrate in gel filtration with recombinant human FKBP (MW 11,820). This gel filtration behavior, which is distinct from that of unmodified mononucleotides, does not reflect binding interactions with FKBP, but is an intrinsic property of these precursors. Therefore, these molecules would be expected to copurify with other low-molecular-weight proteins, especially in the abbreviated purification protocols made possible by freeze-thaw release of recombinant proteins from E. coli (Johnson, B. H., and Hecht, M. H. (1994) BioTechnology 12, 1357-1360). Several alternative strategies are discussed for integrating these findings into the design of improved purification procedures for low-molecular-weight recombinant proteins.     

Reassessment of the vocal repertoire of a nest-building gladiator frog,Boana pardalis (Anura,Hylidae, Cophomantinae): implications for its diagnosis within the B. faber species group

In this study, we re-describe the advertisement and territorial calls of Boana pardalis, carry out an acoustic comparison between the studied species and the other congeners of the B. faber group, and report for the first time the tympanic amplexus for the studied species. The advertisement call of B. pardalis can be used to supplement its diagnosis in the B. faber group based on temporal call traits, e.g. emission rate and emission pattern, as well as the call envelope.     

Characterisation of stroma-dependent blast colony-forming cells in human marrow

Human bone marrow contains a population of haemopoietic progenitor cells that can be distinguished by their ability to adhere to preformed stromal layers (cultured in the presence of methylprednisolone [MP+] and form blast cell colonies. The stromal layers function in the colony assay after they have been heavily irradiated but not after they have been passaged. The binding of the progenitor cells to the stromal cells is complete after 2 hours of coincubation, and stromal layers of 9.6 cm2 can provide adhesion sites for at least 2,000 blast colony-forming cells. The blast colony-forming cells were shown by micromanipulation to self-renew as well as to give rise to multipotential and lineage-committed colony-forming progenitor cells.     

Polymorphisms of DQ β genes in HLA-DR4 haplotypes from healthy and diabetic individuals

The restriction fragment length polymorphism (RFLP) of DQ was assessed in a panel of control and insulin-dependent diabetes (IDD) patients who were serologically typed as HLA-DR4 homozygotes or HLA-DR3, DR4 heterozygotes. Digestions of genomic DNA with Barn HI, Bg1 II, Pst I, Xba I, and Hind III revealed a total of 15 RFLPs in the panel of 71 HLA-DR4 chromosomes. These RFLPs were organized into six allelic groups on the basis of segregation analysis in families. Complete RFLP haplotypes for the 5 restriction enzymes could be constructed for 42 of the HLA-DR4 chromosomes. This analysis revealed 18 RFLP haplotypes of DQ associated with the DR4 chromosomes tested. Two of these haplotypes, designated DQ3.DR4.a and DQ3.DR4.b, accounted for over 50 % of the DR4 chromosomes analyzed. These two haplotypes were antithetical for the RFLPs detected by all five enzymes, indicating that they represent very distinct forms of DQ . The remaining 16 haplotypes were infrequent or unique and were closely related to either a DQ3.DR4.a or DQ3.DR4.b. Two of the RFLPs detected, a 5.8 kb Bg1 II fragment and a 10.5 kb Barn HI fragment, had increased frequencies in disease-associated chromosomes. However, none of the RFLPs we detected exhibited a statistically significant increase in IDD or control populations. In contrast, the DQ3.DR4.b DQ haplotype was significantly decreased in IDD-associated DR4 chromosomes. (P=0.04). These results suggest that the DQ3.DR4.b DQ allele may be protective for the development of IDD.