Biomedical subjects

H Nonami

Publications and source records attributed to H Nonami.

9 recordsLinked to original sources

PubMed2001

Evaluation of pyridoindoles, pyridylindoles and pyridylpyridoindoles as matrices for ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

In an effort to gain an understanding of the processes governing ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI), direct comparison was made of the mass spectra of proteins, carbohydrates and synthetic polymers (polyethylene glycol, polyester and polyamide) by using pyridylindoles, pyridoindoles and pyridylpyridoindoles as UV (337 nm)-MALDI-TOFMS matrices in positive and negative ion mode. In order to study the combined effect of the indole N-H and the pyridine nitrogen of the MALDI matrix on the desorption/ionization process in MALDI, compounds were selected that include either or both of these functions in their structure. Within the compounds studied only those that possess simultaneously both functions in a 1,4-relation behave as very good matrices for proteins. These compounds also work as matrices for some carbohydrates and synthetic polymers used as analytes in the present study. Some of the compounds were also found to be useful for the post-source decay (PSD) analysis of cyclodextrins in positive and negative ion mode. In several cases we also examined the matrix behavior of the corresponding N-methylindole derivatives.

Carbohydrates↗

PubMed2000

Matrix-assisted ultraviolet laser-desorption ionization time-of-flight mass spectrometry of sulfated mannans from the red seaweed Nothogenia fastigiata.

Matrix-assisted ultraviolet laser-desorption ionization time-of-flight mass spectrometry (UV-MALDI-TOF-MS) was applied to sulfated xylo-mannan fractions from Nothogenia fastigiata in order to determine their molecular weights and distribution profiles. The number-average molecular weight calculated from the spectra was similar to that determined by chemical end-group analysis for the lower molecular weight fractions. For the other fractions, the number-average molecular weight was lower than that chemically determined; the increased difference may be attributed to higher desorption difficulties and, consequently, mass-dependent discrimination. A reconstructed spectrum, using the peaks obtained from all the fractions, suggested an unimodal distribution. The best results were obtained by using 2,5-dihydroxybenzoic acid as matrix doped with 1-hydroxyisoquinoline and with harmane and nor-harmane.

Gentisates↗

PubMed1998

beta-Carboline alkaloids as matrices for UV-matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in positive and negative ion modes. Analysis of proteins of high molecular mass, and of cyclic and acyclic oligosaccharides.

We report that commercially available beta-carbolines (nor-harmane (9H-pyrido[3,4-b]indole), harmane (1-methyl-9H-pyrido[3,4-b]indole), harmine (7-methoxy-1-methyl-9H-pyrido[3,4-b]indole), harmol (1-methyl-9H-pyrido[3,4-b]indol-7-ol), harmaline (3,4-dihydro-7-methoxy-1-methyl-9H-pyrido[3,4-b]indole) and harmalol (3,4-dihydro-1-methyl-9H-pyrido[3,4-b]indol-7-ol)), are useful MALDI matrices at 337 nm, for cyclic oligosaccharides (cyclodextrins, range 972-1290 Da), acyclic oligosaccharides (range 342-828 Da) and high molecular mass proteins (range 23,290-66,525 Da) in both positive and negative modes. This was investigated by using time-of-flight (TOF) mass spectrometers of different sensitivities, equipped with and without pulse extraction facilities. A comparison with conventional matrices for carbohydrates (DHB and DHB/HIC) indicates that beta-carbolines provide the same level of sensitivity and resolution in the positive mode, but offer the advantage of high levels of sensitivity and resolution in the negative mode. Harmaline has been found to be specially effective for the analysis of high-mass proteins in both modes, and also exhibits excellent experimental reproducibility of the results owing to the homogeneous crystallization of the analyte-matrix mixture over the entire sample surface area. Harmane and nor-harmane are both excellent matrices for high-mass proteins also. As MALDI matrices, beta-carbolines permit measurement of sulfated sugars in the negative ion mode as ([M-H]), and of neutral sugars and proteins as both [M + H]+ and [M-H]- in appropriate modes.

Carbolines↗

PubMed1997

[The roles of various media in the decision making processes for recycling behavior: a path analysis model].

This study researched the effects of cognitive variables on recycling behavior, as well as effects of various media of influence on the cognition and behavior. According to Hirose (1994), the decision making process for recycling consists of two steps. The first leads to goal intention of an ecological lifestyle. The second is related to behavior intention of recycling in line with the goal intention. Mass media, such as newspaper and TV, are thought to influence beliefs about environmental problems, including three determinants of goal intention: perception of seriousness, responsibility, and effectiveness. Personal media, such as personal contacts with pro-environmental activists, are thought to influence evaluation of behavior, including three determinants of behavior intention: evaluation of feasibility, cost and benefits, and social norms. Local media, such as municipal announcement and circular, are hypothesized to have a mixed effect of the two. Path analysis indicated that goal intention affected recycling behavior through behavior intention. Effects of the three media of influence on the cognitive variables were also consistent with the hypothesis.

Behavior↗

PubMed1990

Primary events regulating stem growth at low water potentials.

Cell enlargement is inhibited by inadequate water. As a first step toward understanding the mechanism, all the physical parameters affecting enlargement were monitored to identify those that changed first, particularly in coincidence with the inhibition. The osmotic potential, turgor, yield threshold turgor, growth-induced water potential, wall extensibility, and conductance to water were measured in the elongating region, and the water potential was measured in the xylem of stems of dark-grown soybean (Glycine max [L.] Merr.) seedlings. A stepdown in water potential was achieved around the roots by transplanting the seedlings to vermiculite of low water content, and each of the parameters was measured simultaneously in the same plants while intact or within a few minutes of being intact using a newly developed guillotine psychrometer. The gradient of decreasing water potential from the xylem to the enlarging cells (growth-induced water potential) was the first of the parameters to decrease to a growth-limiting level. The kinetics were the same as for the inhibition of growth. The decreased gradient was caused mostly by a decreased water potential of the xylem. This was followed after 5 to 10 hours by a similar decrease in cell wall extensibility and tissue conductance for water. Later, the growth-induced water potential recovered as a result of osmotic adjustment and a rise in the water potential of the xylem. Still later, moderate growth resumed at a rate apparently determined by the low wall extensibility and tissue conductance for water. The turgor did not change significantly during the experiment. These results indicate that the primary event during the growth inhibition was the change in the growth-induced water potential. Because the growth limitation subsequently shifted to the low wall extensibility and tissue conductance for water, the initial change in potential may have set in motion subsequent metabolic changes that altered the characteristics of the wall and cell membranes.

Journal Article↗

PubMed1990

Wall extensibility and cell hydraulic conductivity decrease in enlarging stem tissues at low water potentials.

Measurements with a guillotine psychrometer (H Nonami, JS Boyer [1990] Plant Physiol 94: 1601-1609) indicate that the inhibition of stem growth at low water potentials (low psi(w)) is accompanied by decreases in cell wall extensibility and tissue hydraulic conductance to water that eventually limit growth rate in soybean (Glycine max L. Merr.). To check this conclusion, we measured cell wall properties and cell hydraulic conductivities with independent techniques in soybean seedlings grown and treated the same way, i.e. grown in the dark and exposed to low psi(w) by transplanting dark grown seedlings to vermiculite of low water content. Wall properties were measured with an extensiometer modified for intact plants, and conductances were measured with a cell pressure probe in intact plants. Theory was developed to relate the wall measurements to those with the psychrometer. In the elongation zone, the plastic deformability of the walls decreased when measured with the extensiometer while growth was inhibited at low psi(w). It increased during a modest growth recovery. This behavior was the same as that for the wall extensibility observed previously with the psychrometer. Tissue that was killed before measurement with the extensiometer also showed a similar response, indicating that changes in wall extensibility represented changes in wall physical properties and not rates of wall biosynthesis. The elastic compliance (reciprocal of bulk elastic modulus) did not change in the elongating or mature tissue. The hydraulic conductivity of cortical cells decreased in the elongating tissue and increased slightly during growth recovery in a response similar to that observed with the psychrometer. We conclude that the plastic properties of the cell walls and the conductance of the cells to water were decreased at low psi(w) but that the elastic properties of the walls were of little consequence in this response.

Journal Article↗

PubMed1989

Turgor and growth at low water potentials.

Turgor affects cell enlargement but has not been measured in enlarging tissue of intact plants when growth is inhibited by inadequate water. Mature or excised tissue can be problematic for these measurements because turgor may not be the same as in intact enlarging cells. Therefore, we measured the average turgor in the elongating region of intact stems of soybean (Glycine max [L.] Merr.) while the seedlings were exposed to low water potentials by transplanting to vermiculite of low water content. Stem growth was completely inhibited by the transplanting, and the average turgor decreased in the mature stem tissue. However, it did not decrease in the elongating region whether measured in intact or excised tissue (total of four methods). At the cellular level, turgor was uniform in the elongating tissue except at transplanting, when turgor decreased in a small number of cortical cells near the xylem. The reduced turgor in these cells, but constant turgor in most of the cells, confirmed that no general turgor loss had occurred but indicated that gradients in water potential extending from the xylem into the enlarging tissue were reduced, thus decreasing the movement of water into the tissue for cell enlargement. A modest growth recovery occurred after 2 days and was preceded by a recovery of the gradient. This suggests that under these conditions, growth initially was inhibited not by turgor loss but by a collapse of the water potential gradient necessary for the growth process.

Journal Article↗

PubMed1987

Pressure probe and isopiestic psychrometer measure similar turgor.

Turgor measured with a miniature pressure probe was compared to that measured with an isopiestic thermocouple psychrometer in mature regions of soybean (Glycine max [L.] Merr.) stems. The probe measured turgor directly in cells of intact stems whereas the psychrometer measured the water potential and osmotic potential of excised stem segments and turgor was calculated by difference. When care was taken to prevent dehydration when working with the pressure probe, and diffusive resistance and dilution errors with the psychrometer, both methods gave similar values of turgor whether the plants were dehydrating or rehydrating. This finding, together with the previously demonstrated similarity in turgor measured with the isopiestic psychrometer and a pressure chamber, indicates that the pressure probe provides accurate measurements of turgor despite the need to penetrate the cell. On the other hand, it suggests that as long as precautions are taken to obtain accurate values for the water potential and osmotic potential, turgor can be determined by isopiestic psychrometry in tissues not accessible to the pressure probe for physical reasons.

Journal Article↗

PubMed1987

Origin of growth-induced water potential : solute concentration is low in apoplast of enlarging tissues.

We developed a new method to measure the solute concentration in the apoplast of stem tissue involving pressurizing the roots of intact seedlings (Glycine max [L.] Merr. or Pisum sativum L.), collecting a small amount of exudate from the surface of the stem under saturating humidities, and determining the osmotic potential of the solution with a micro-osmometer capable of measuring small volumes (0.5 microliter). In the elongating region, the apoplast concentrations were very low (equivalent to osmotic potentials of -0.03 to -0.04 megapascal) and negligible compared to the water potential of the apoplast (-0.15 to -0.30 megapascal) measured directly by isopiestic psychrometry in intact plants. Most of the apoplast water potential consisted of a negative pressure that could be measured with a pressure chamber (-0.15 to -0.28 megapascal). Tests showed that earlier methods involving infiltration of intercellular spaces or pressurizing cut segments caused solute to be released to the apoplast and resulted in spuriously high concentrations. These results indicate that, although a small amount of solute is present in the apoplast, the major component is a tension that is part of a growth-induced gradient in water potential in the enlarging tissue. The gradient originates from the extension of the cell walls, which prevents turgor from reaching its maximum and creates a growth-induced water potential that causes water to move from the xylem at a rate that satisfies the rate of enlargement. The magnitude of the gradient implies that growing tissue contains a large resistance to water movement.

Journal Article↗