Missing mass in collisional debris from galaxies

Recycled dwarf galaxies can form in the collisional debris of massive galaxies. Theoretical models predict that, contrary to classical galaxies, these recycled galaxies should be free of nonbaryonic dark matter. By analyzing the observed gas kinematics of such recycled galaxies with the help of a numerical model, we demonstrate that they do contain a massive dark component amounting to about twice the visible matter. Staying within the standard cosmological framework, this result most likely indicates the presence of large amounts of unseen, presumably cold, molecular gas. This additional mass should be present in the disks of their progenitor spiral galaxies, accounting for a substantial part of the so-called missing baryons.     

Chlorpromazine and its metabolites alter polymerization and gelation of actin

Hepatic hydroxylated metabolites of chlorpromazine (10(-5)M to 10(-4)M), a frequently used phenothiazine tranquilizer, produce solid gel formation with filamentous actin, but the less toxic chlorpromazine sulfoxide metabolite does not. At higher concentrations (5 x 10(-4)M) chlorpromazine inhibits actin polymerization. These dose-response relationships parallel the drug's hepatic toxicity in vivo and suggest that interactions between chloropromazine or chlorpromazine metabolites and actin could be an underlying mechanism of cell injury.     

A heat-sensitive TRP channel expressed in keratinocytes

Mechanical and thermal cues stimulate a specialized group of sensory neurons that terminate in the skin. Three members of the transient receptor potential (TRP) family of channels are expressed in subsets of these neurons and are activated at distinct physiological temperatures. Here, we describe the cloning and characterization of a novel thermosensitive TRP channel. TRPV3 has a unique threshold: It is activated at innocuous (warm) temperatures and shows an increased response at noxious temperatures. TRPV3 is specifically expressed in keratinocytes; hence, skin cells are capable of detecting heat via molecules similar to those in heat-sensing neurons.     

A mitotic septin scaffold required for Mammalian chromosome congression and segregation

Coordination of cytokinesis with chromosome congression and segregation is critical for proper cell division, but the mechanism is unknown. Here, septins, a conserved family of polymerizing guanosine triphosphate-binding proteins, localized to the metaphase plate during mitosis. Septin depletion resulted in chromosome loss from the metaphase plate, lack of chromosome segregation and spindle elongation, and incomplete cytokinesis upon delayed mitotic exit. These defects correlated with loss of the mitotic motor and the checkpoint regulator centromere-associated protein E (CENP-E) from the kinetochores of congressing chromosomes. Mammalian septins may thus form a mitotic scaffold for CENP-E and other effectors to coordinate cytokinesis with chromosome congression and segregation.     

Limitations of corn (Zea mays) and common bean (Phaseolus vulgaris) diets as protein and calorie sources

Mixtures of 70:30 and 87:13 of corn and beans with or without vitamins, minerals, limiting amino acids and calories were fed to 5-week-old pigs to determine performance and efficiency of utilization. After 12 weeks it was shown that increasing the ratio from 87:13 to 70:30 (corn:beans) was a desirable measure as was the simultaneous supplementation with the other nutrients; individual groups of nutrients resulted in partial improvement in animal performance. None of the diets used was capable of inducing growth similar to the control groups fed a corn:soya diet. Results confirm the importance of total nutrients to obtain increased efficiency of protein utilization; furthermore, diets, such as the corn:bean diets studied, need to be improved in relation to both quality and quantity of protein.INCAP Publication I-1144     

Quercetin exhibits a specific fluorescence in cellular milieu: a valuable tool for the study of its intracellular distribution

The elaboration of novel techniques for flavonoid intracellular tracing would elucidate the compounds' absorption and bioavailability and assist molecular and pharmacological approaches, as they are promising candidates for drug development. This study exploited the properties of quercetin (3,3',4',5,7-pentahydroxyflavone), found in high concentrations in the majority of edible plants. Through the use of UV-vis spectroscopy, confocal microscopy, and HPLC-ESI-MS, native quercetin, at physiologically relevant concentrations, was found to exhibit a specific fluorescence (488 nmex/500-540 nmem) upon internalization. This fluorescence shift is due to a non-covalent binding to intracellular targets (probably proteins) and compatible with the settings applied in confocal microscopy. This property provides a valuable, selective alternative technique for quercetin tracing in cellular systems, permitting the quantitative evaluation of its transit at pharmacologically relevant concentrations and the validation of a number of already described molecular functions.