Cladistic association analysis of Y chromosome effects on alcohol dependence and related personality traits

Association between Y chromosome haplotype variation and alcohol dependence and related personality traits was investigated in a large sample of psychiatrically diagnosed Finnish males. Haplotypes were constructed for 359 individuals using alleles at eight loci (seven microsatellite loci and a nucleotide substitution in the DYZ3 alphoid satellite locus). A cladogram linking the 102 observed haplotype configurations was constructed by using parsimony with a single-step mutation model. Then, a series of contingency tables nested according to the cladogram hierarchy were used to test for association between Y haplotype and alcohol dependence. Finally, using only alcohol-dependent subjects, we tested for association between Y haplotype and personality variables postulated to define subtypes of alcoholism—antisocial personality disorder, novelty seeking, harm avoidance, and reward dependence. Significant association with alcohol dependence was observed at three Y haplotype clades, with significance levels of P = 0.002, P = 0.020, and P = 0.010. Within alcohol-dependent subjects, no relationship was revealed between Y haplotype and antisocial personality disorder, novelty seeking, harm avoidance, or reward dependence. These results demonstrate, by using a fully objective association design, that differences among Y chromosomes contribute to variation in vulnerability to alcohol dependence. However, they do not demonstrate an association between Y haplotype and the personality variables thought to underlie the subtypes of alcoholism.

Temperature and length scale dependence of hydrophobic effects and their possible implications for protein folding

The Lum–Chandler–Weeks theory of hydrophobicity [Lum, K., Chandler, D. & Weeks, J. D. (1999) J. Phys. Chem. 103, 4570–4577] is applied to treat the temperature dependence of hydrophobic solvation in water. The application illustrates how the temperature dependence for hydrophobic surfaces extending less than 1 nm differs significantly from that for surfaces extending more than 1 nm. The latter is the result of water depletion, a collective effect, that appears at length scales of 1 nm and larger. Because of the contrasting behaviors at small and large length scales, hydrophobicity by itself can explain the variable behavior of entropies of protein folding.

Scale dependence in earthquake phenomena and its relevance to earthquake prediction.

The recent discovery of a low-velocity, low-Q zone with a width of 50-200 m reaching to the top of the ductile part of the crust, by observations on seismic guided waves trapped in the fault zone of the Landers earthquake of 1992, and its identification with the shear zone inferred from the distribution of tension cracks observed on the surface support the existence of a characteristic scale length of the order of 100 m affecting various earthquake phenomena in southern California, as evidenced earlier by the kink in the magnitude-frequency relation at about M3, the constant corner frequency for earthquakes with M below about 3, and the sourcecontrolled fmax of 5-10 Hz for major earthquakes. The temporal correlation between coda Q-1 and the fractional rate of occurrence of earthquakes in the magnitude range 3-3.5, the geographical similarity of coda Q-1 and seismic velocity at a depth of 20 km, and the simultaneous change of coda Q-1 and conductivity at the lower crust support the hypotheses that coda Q-1 may represent the activity of creep fracture in the ductile part of the lithosphere occurring over cracks with a characteristic size of the order of 100 m. The existence of such a characteristic scale length cannot be consistent with the overall self-similarity of earthquakes unless we postulate a discrete hierarchy of such characteristic scale lengths. The discrete hierarchy of characteristic scale lengths is consistent with recently observed logarithmic periodicity in precursory seismicity.

Solvent dependence of dynamic transitions in protein solutions

A transition as a function of increasing temperature from harmonic to anharmonic dynamics has been observed in globular proteins by using spectroscopic, scattering, and computer simulation techniques. We present here results of a dynamic neutron scattering analysis of the solvent dependence of the picosecond-time scale dynamic transition behavior of solutions of a simple single-subunit enzyme, xylanase. The protein is examined in powder form, in D2O, and in four two-component perdeuterated single-phase cryosolvents in which it is active and stable. The scattering profiles of the mixed solvent systems in the absence of protein are also determined. The general features of the dynamic transition behavior of the protein solutions follow those of the solvents. The dynamic transition in all of the mixed cryosolvent–protein systems is much more gradual than in pure D2O, consistent with a distribution of energy barriers. The differences between the dynamic behaviors of the various cryosolvent protein solutions themselves are remarkably small. The results are consistent with a picture in which the picosecond-time scale atomic dynamics respond strongly to melting of pure water solvent but are relatively invariant in cryosolvents of differing compositions and melting points.