Solvent effects on the cooperative order-disorder transition of aqueous solutions of schizophyllan, a triple-helical polysaccharide

A triple helical polysaccharide schizophyllan in aqueous solution exhibited a highly cooperative transition between ordered and disordered states associated with the conformation of its side chains and nearby water molecules. The transition was followed by optical rotation and calorimetry using water containing additives such as NaOH and DMSO as solvents. The ordered state was stabilized or destabilized depending on the kind and amount of the additive employed; in particular, the addition of DMSO had a remarkable stabilizing effect. This effect was analyzed by means of a statistical mechanical theory of linear cooperative transitions, where DMSO was assumed to interact favorably with the ordered side chains. A small amount of NaOH in a solvent mixture stabilized the ordered state and made the transition curve very gradual. No molecular mechanism was elucidated to account for the role of NaOH.     

Development of the hand and wrist bones in chimpanzees

Skeletal developmental of chimpanzees was studied cross-sectionally. By application of the TW2 method, we described the skeletal development of chimpanzees and compared their skeletal development with humans'. A development pattern of chimpanzees repeated accelerations and decelerations displaying “early-juvenile trough,” “pre-adolescent peak,” “mid-adolescent trough,” and “post-adolescent peak” in incremental curves. Sex differences in skeletal development are slower development in males during infant and early juvenile phases, and greater increment around the adolescent phase in males. Females are fully mature at younger ages than males, e.g. about one and a half years. In comparison with chimpanzees, humans have such characteristics as a longer slower period of juvenile development and a shorter spurt-like adolescent fast period which ends with full maturity.     

Heritable pulmonary lobation anomaly in the rat

A new mutant gene which caused fusion of lung lobes was found in the Wistar rat. The genetic analysis revealed an autosomal recessive inheritance and the mutant gene was named fused pulmonary lobes (gene symbol: fpl). The right lung of the fpl/fpl homozygotes had fused lobes of varying degrees. The fpl/fpl homozygotes were semilethal at the neonatal stage and had externally visible associated malformations such as malocclusion of incisors, eyelid anomalies, and digit abnormalities in the fore- and hindlimbs with different incidences. These traits were considered to be caused by the pleiotropic effects of the fpl gene.     

Sequential polypeptides: 5. Statistical mechanical analysis of helix-coil transition in sequential polypeptides

A statistical mechanical theory of the helix-coil transition in sequential polypeptides is developed assuming that the statistical weights of the Zimm-Bragg parameters of a given residue depend on the type of adjacent residues. In the case of a sequential polypeptide consisting of two kinds of residues, the theory describes the helix- coil transition of the polypeptide in terms of the Zimm-Bragg parameters associated with the corresponding residues. The theory is then used to determine this parameter, as a function of temperature, from experimental data for transition temperature as a function of solvent composition, for a series of sequential polypeptides consisting of Glu(OBzl) and Lys(Chz) residues in mixtures of dichloroacetic acid and 1,2-dichlorethane. This parameter is then combined with the Zimm-Bragg parameters for the parent homopolypeptides, and the theory used to predict helix coil transition curves which are in good agreement with the experimental ones for the sequential polypeptides studied.     

Effects of different light intensities during the forenoon on the afternoon thermal sensation in mild cold

1. 1. The study aimed at knowing whether thermal sensation during afternoon cool exposure could be influenced by bright light (4000 lx) or dim light (200 lx) in the forenoon.

2. 2. The subjects felt cooler after exposure to dim light than to bright light.

3. 3. Melatonin in the urine was significantly higher in bright light than in dim light at 10:30 h and at noon.

     

The Daily Rhythms in the Core Temperature during Spring and Autumn under Natural Conditions in Young Women

Studies of the daily rectal temperature rhythms during May and October-November in three female subjects leading normal lives under natural conditions disclosed that although a rhythm of rectal temperature existed in all three subjects in both seasons, the temperature level seems to be lower in October-November than in May, especially during the nighttime. The phasing of the rectal temperature rhythm did not seem to differ between the two seasons.     

Structural Change of DNA Induced by Nucleoid Proteins: Growth Phase-Specific Fis and Stationary Phase-Specific Dps

The effects of nucleoid proteins Fis and Dps of Escherichia coli on the higher order structure of a giant DNA were studied, in which Fis and Dps are known to be expressed mainly in the exponential growth phase and stationary phase, respectively. Fis causes loose shrinking of the higher order structure of a genome-sized DNA, T4 DNA (166 kbp), in a cooperative manner, that is, the DNA conformational transition proceeds through the appearance of a bimodal size distribution or the coexistence of elongated coil and shrunken globular states. The effective volume of the loosely shrunken state induced by Fis is 30–60 times larger than that of the compact state induced by spermidine, suggesting that cellular enzymes can access for DNA with the shrunken state but cannot for the compact state. Interestingly, Dps tends to inhibit the Fis-induced shrinkage of DNA, but promotes DNA compaction in the presence of spermidine. These characteristic effects of nucleotide proteins on a giant DNA are discussed by adopting a simple theoretical model with a mean-field approximation.     

The endosomal trafficking regulator LITAF controls the cardiac Nav1.5 channel via the ubiquitin ligase NEDD4-2

The QT interval is a recording of cardiac electrical activity. Previous genome-wide association studies identified genetic variants that modify the QT interval upstream of LITAF (lipopolysaccharide-induced tumor necrosis factor-α factor), a protein encoding a regulator of endosomal trafficking. However, it was not clear how LITAF might impact cardiac excitation. We investigated the effect of LITAF on the voltage-gated sodium channel Nav1.5, which is critical for cardiac depolarization. We show that overexpressed LITAF resulted in a significant increase in the density of Nav1.5-generated voltage-gated sodium current I_Na and Nav1.5 surface protein levels in rabbit cardiomyocytes and in HEK cells stably expressing Nav1.5. Proximity ligation assays showed co-localization of endogenous LITAF and Nav1.5 in cardiomyocytes, whereas co-immunoprecipitations confirmed they are in the same complex when overexpressed in HEK cells. In vitro data suggest that LITAF interacts with the ubiquitin ligase NEDD4-2, a regulator of Nav1.5. LITAF overexpression down-regulated NEDD4-2 in cardiomyocytes and HEK cells. In HEK cells, LITAF increased ubiquitination and proteasomal degradation of co-expressed NEDD4-2 and significantly blunted the negative effect of NEDD4-2 on I_Na. We conclude that LITAF controls cardiac excitability by promoting degradation of NEDD4-2, which is essential for removal of surface Nav1.5. LITAF-knockout zebrafish showed increased variation in and a nonsignificant 15% prolongation of action potential duration. Computer simulations using a rabbit-cardiomyocyte model demonstrated that changes in Ca²⁺ and Na⁺ homeostasis are responsible for the surprisingly modest action potential duration shortening. These computational data thus corroborate findings from several genome-wide association studies that associated LITAF with QT interval variation.