Phosphatidylinositol inhibits microtubule assembly by binding to microtubule-associated protein 2 at a single, specific, high-affinity site.

The effects of various anionic phospholipids on the in vitro assembly of MAP2/tubulin microtubules has been examined. We show that the potency to inhibit is related to the polarity of the phospholipids and that this is consistent with a mode of action involving the sequencing of microtubule-associated proteins (MAPs) by nonspecific electrostatic interactions. The inhibitory potency of phosphatidylinositol (PI) is, however, considerably larger than predicted by this model. The effects of PI on MAP2/tubulin microtubule assembly have therefore been examined in greater detail by preparing phosphatidylcholine (PC) liposomes doped with increasing amounts of PI. We show that when the PI is sufficiently dispersed by dilution with PC, it inhibits microtubule assembly by binding to MAP2 with an apparent stoichiometry, after correction for the bilamellar nature of the liposomes, of 1:1 mol.mol-1 PI:MAP2. Furthermore, we show that the Kd of this interaction is in the submicromolar range.     

Black and Hispanic Men Perceived to Be Large Are at Increased Risk for Police Frisk,Search, and Force

Social justice issues remain some of the most pressing problems in the United States. One aspect of social justice involves the differential treatment of demographic groups in the criminal justice system. While data consistently show that Blacks and Hispanics are often treated differently than Whites, one understudied aspect of these disparities is how police officers'' assessments of suspects'' size affects their decisions. Using over 3 million cases from the New York Police Department (NYPD) Stop, Question, and Frisk (SQF) Database, 2006–2013, this study is the first to explore suspects'' race, perceived size, and police treatment. Results indicate that tall and heavy black and Hispanic men are at the greatest risk for frisk or search. Tall and heavy suspects are at increased risk for experiencing police force, with black and Hispanic men being more likely to experience force than white men across size categories.     

Mouse monoclonal antibodies can nonspecifically inhibit the proliferation of human T-cell growth factor-dependent T cells

A large series of mouse monoclonal antibodies was found to inhibit the proliferation of T-cell growth factor (TCGF)-dependent human T-cell blasts as measured by the incorporation of tritiated thymidine. The specificity of the antibody appeared to be irrelevant for inhibition and two T-cell-specific antibodies did not prevent the absorption of TCGF by treated T cells. It is suggested that the antibodies function by the indirect release of suppressor factors by Fc receptor-bearing TCGF-dependent cells.     

A major outer-membrane protein functions as a porin in Haemophilus influenzae

Porins are pore-forming outer-membrane proteins which serve as a non-specific pathway for the entry of hydrophilic molecules into Gram-negative bacteria. We studied four strains of Haemophilus influenzae that had decreased permeability to chloramphenicol associated with diminished quantities of a 40 kDa major outer-membrane protein. Isogenic pairs of organisms containing and lacking this protein were compared. The latter strains grew more slowly and were less permeable to sucrose and raffinose. They were also more resistant to multiple hydrophilic antibiotics than an isogenic strain containing the 40 kDa protein and were less permeable to penicillin G and chloramphenicol. We conclude that the 40 kDa outer-membrane protein functions as a porin in H. influenzae.     

Influence of neighbouring base sequence on N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis in the lacI gene of Escherichia coli

N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced forward mutations within the first 540 base-pairs of the lacI gene of Escherichia coli were cloned and sequenced. In total, 167 MNNG-induced independent mutations were characterized, with G.C to A.T transitions accounting for all but three of the mutations. This mutagenic specificity is consistent with the mispairing predicted by the methylation of the O6 position of guanine. The characterization of such large numbers of mutations permitted an analysis of the influence of local DNA sequence on mutagenesis. This analysis revealed a strong influence by the 5' flanking base. On average, guanine residues preceded (5') by a guanine or an adenine residue were, respectively, nine times and five times more likely to mutate after treatment with MNNG than those preceded by a pyrimidine residue.