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Functional properties of living cells depend on the thermodynamic variables such as temperature and pressure. A unique tool to investigate volume effects on structure and metabolism of the cell and biomolecules is pressure perturbation. We have developed a new setup that enables micro-spectroscopy and optical imaging of individual live cells at variable pressure from 0.1 to 400 MPa. Following characterization of the setup, pressure and temperature effects on the secondary structure of the peptide Poly-L-glutamic acid (PGA) in deuterated water buffer solution were investigated. The amide I band of PGA is sensitive to pressure and temperature, and by spectral deconvolution, we determined the relative contributions due to the ?-helix and random coil conformations. The population of ?-helix increases with increasing pressure. Pressure effects on single red blood cells and the intracellular protein hemoglobin were studied by micro-Raman spectroscopy. In particular, we observed a shift in the frequency of the iron-histidine vibrational band in both the intracellular hemoglobin and hemoglobin in solutions. The iron-histidine mode is a sensitive structural marker of the crucial iron-protein linkage in heme proteins. The pressure dependent shift suggests a conformational change of the heme environment. This finding was further supported by micro-absorption measurements at variable pressure. In additional experiments, Raman spectroscopy was employed to probe molecular changes that occurred in hemoglobin in erythrocytes infected with the malaria parasite Plasmodium falciparum. The spectra of infected cells indicated that hemoglobin degradation can be correlated with the stages of the parasite multiplication cycle. The research was further extended towards probing size and shape changes of individual cells with pressure. The lateral diameter in yeast cells was observed to decrease with pressure in a reversible way. These results suggest that transport of the intra-cellular water may play a significant role for volume changes. In summary, pressure changes were shown to induce conformational changes in proteins and shape changes in yeast cells. A Raman technique was developed to monitor the states of Plasmodium falciparum multiplication cycle within a red blood cell.

This study investigates the role of perceptual distinctiveness in consonant inventories. While distinctiveness appears to play a role in the shaping of vowel systems, a literature review indicates that its status in consonant selections remains unclear. To address this issue I used speech materials recorded by a trained phonetician containing 35 CV syllables with seven places of articulation (bilabial, dental, alveolar, retroflex, palatal, velar and uvular) and five vowels: [i] [[epsilon]] [a] [[backwards c]] and [u]. Detailed acoustic measurements were performed: formant patterns at vowel onsets (loci) and vowel midpoints, transitions rates and burst spectra. To validate the speech material, comparisons were made with published data and with formant frequencies derived by means of an articulatory model. Perceptual data were collected on these 35 syllables. Multiple Regression analyses were performed with the coded dissimilarities as the dependent variable and with (combinations of) formant-based distances, time constant differences and burst differences as the independent variables. The results indicated that acoustic measurements could be successfully used to help explain listener responses. Optimal place sets were obtained from a rank ordering of the CV syllables with respect to 'individual salience' (defined as the sum of a syllable's perceptual distance to other places in the same vowel context) and from a replication of the Liljencrants & Lindblom systemic criterion of maximizing distances within all vowel pairs. Instead of the typologically prevalent pattern of [b d g], predictions were found to be vowel-dependent and to often favor CV:s located at the 'corners' of the acoustic F3-F2 space, viz., uvular, palatal and retroflex. This finding leads to a conclusion that distinctiveness alone is unlikely to account for how languages use place of articulation in voiced stops. For more successful attempts, future work should be directed towards defining and incorporating production constraints such as 'ease of articulation'.

Ascaris suum NAD-malic enzyme catalyzes the decarboxylation of oxalacetate and reduction of pyruvate. Thus, the present classification (E.C. 1.1.1.39) for this enzyme should be changed to E.C. 1.1.1.38. In the absence of nucleotide, both the chicken liver NADP-malic enzyme and Ascaris suum NAD-malic enzymes catalyze the decarboxylation of oxalacetate. A study of the pH dependence of kinetic parameters for oxalacetate decarboxylation and pyruvate reduction was carried out for the NAD(P)-malic enzyme with Mg^2+ and Mn^2+ in the presence and absence of nucleotide. In all cases, an enzyme residue is required in its protonated form for reaction while for oxalacetate decarboxylation the β-carboxyl of oxalacetate is required unprotonated. Of a number of inhibitory binding analogs of malate tested, oxalate is the tightest binding inhibitor for Ascaris suum enzyme.