Annual survival rate and age structure of habu,Trimeresurus flavoviridis (Viperidae), on Minna island,Japan: Estimation from removal trapping

A population of a viperid snake,Trimeresurus flavoviridis, was studied over 10 years by removal trapping on a small subtropical island in Japan. The sex ratio of trapped individuals changed seasonally, but was not biased to either sex in the whole sample of 258 individuals. The age of each individual was estimated through the size structure and the age-size relationship. The minimum number of individuals at the beginning of the study was estimated through accumulating older individuals trapped in the subsequent years. By assuming an annual natural survival rate in the course of this accumulation, an age structure was simulated which led to calculate a resulted natural survival rate. The assumed rate of 0.62 fitted best to the resulted one. The annual trapped proportion estimated on the simulated absolute number of individuals was higher in older individuals than in younger ones with the overall mean of 16%.     

Influence of phosphate ion on the fluorescence of 3-fluorotyrosine

Summary 3-Fluorotyrosine fluorescence is quenched effectively by phosphate ions not only by a dynamic but also by a static mechanism owing to H-bond complex formation in ground state. 3-Fluorotyrosine pK_a values both in the ground and first excited state (8.3 and 4, respectively) are appreciably lower than those of tyrosine, thus promoting 3-fluorotyrosinate ion formation in the excited state. Additional emission owing to 3-fluorotyrosinate ion (near 350 nm) may be taken erroneously for tryptophan fluorescence.     

Mediterranean juvenile bluefin tuna: life history patterns

As there is a lack of information on the growth and migrations of bluefin tuna, information about them was gathered using the structural and chemical characteristics of their otoliths and mercury levels in body tissues as indicators of physiological and habitat characteristics. The otoliths of juvenile tuna caught in the Spanish Mediterranean littoral were studied. Otolith increments, assumed to be formed daily, were enumerated. Measurements by wavelength dispersive electron microprobe confirmed the presence of strontium in otolith tissue, and an inverse relationship between strontium/calcium (Sr/Ca) concentration ratio and temperature is suggested. Electron microprobe analyses combined with daily increment analyses of otoliths provided life history profiles for individual fish. Additional Sr/Ca concentration ratio data on fish supported the idea that Sr/Ca ratios can provide information on the environmental history of individual fish. Body concentrations of mercury were related to otolith analyses to suggest age structure, critical life history periods, growth environment, stock structure, food web position, and migration history. The techniques applied present an innovative approach to management-related problems, and the combination of chemical analyses with structural analyses promises to expand our knowledge of the life history of migratory fishes.     

Transpiration and drought resistance of Douglas-fir seedlings exposed to excess ammonium

 In a pot trial growth and transpiration of 3-year-old Douglas-fir seedlings on an acid, sandy soil was examined at a deficient (30 kg N ha^{–  1} year^{–  1}) and an excessive level (120 kg N ha^{–  1} year^{–  1}) of NH₄ application. Dissolved ammonium sulphate was applied to the pots weekly for two growing seasons. In half of the pots a complete set of other nutrients was applied in optimal proportions to the applied nitrogen. Water supply was optimal and transpiration was recorded. At the end of the second treatment season irrigation was stopped for 2 weeks during dry and sunny weather. Both high application of NH₄ and additional nutrients increased shoot growth and transpiration demand in the first treatment year. The root system was smaller at higher N level and this reduced water uptake accordingly. In the second year the combination of high NH₄ ⁺ and additional nutrients affected root functioning predominantly due to salinity effects and this seriously decreased water uptake capacity and shoot water potentials, finally resulting in tree death. Without addition of other nutrients the high NH₄ ⁺ application resulted in a high degree of soil acidification, which damaged the roots, that showed a decrease in water uptake capacity. At the low NH₄ supply level soil acidification was lower, and root functioning was not affected, and the trees recovered quickly from the imposed drought. Higher needle K and P status depressed transpiration rates at the low NH₄ application rate. Received: 9 January 1995 / Accepted: 18 September 1995     

Site-specific isotope fractionation of hydrogen in the biosynthesis of plant fatty acids

The overall deuterium content of plant lipids has been investigated by isotope ratio mass spectrometry (IRMS), and the site-specific natural isotope fractionation of hydrogen has been studied by ²H-NMR at natural abundance (SNIF-NMR). An analytical strategy has been developed in order to exploit the isotopomeric composition determined in clusters associated with different chemical sites of one or several fatty acid components. The method, which combines spectrometric and chromatographic data, enables isotopic criteria to be directly derived from raw vegetable oils containing in general two saturated and two unsaturated fatty acids. These results provide new information on isotopic fractionation caused by biochemical, physiological and natural environmental effects. Some alternation in the molecular deuterium distribution has been detected which may be related to the mechanism of fatty acid elongation. The successive methylene groups introduced through malonyl CoA are the subjects of different kinetic isotope effects since one of them is exclusively derived from NADH whereas the other has a contribution from pyruvate. A discriminant analysis of the cluster isotopic parameters enables several kinds of botanical precursors to be distinguished. The authenticating performances can be improved by taking into account the influence of climatic effects related to the region in which the plant grew.     

Root water uptake of field-growing plants indicated by measurements of natural-abundance deuterium

Measurements of stable-isotope ratios of water extracted from stems and, in some studies, soils are increasingly being used to study the integrated root function of field-growing plants. This study explored if additional measurements on water extracted from roots could indicate the activity of roots in different areas of the soil profile and their influence on canopy water sources, so providing advantages over more common sampling strategies. Studies were conducted on trees and shrubs located in diverse habitats: a saline, semi-arid floodplain, a subhumid mountain-range front and a cold desert. At each site, roots, soil immediately surrounding the roots, and plant stems were sampled. Roots were taken from different depths in the soil, to approximately 2 m at one site. Overall, 80% of roots sampled had H isotope ratios different from the surrounding soil. The differences up to 37, were significant (p<0.05) at two of the sites. Thus water in most of the roots sampled did not come entirely, if at all, from the surrounding soil, illustrating movement and possible mixing of water within the root system. This condition was not simply related to the availability of water surrounding the soil, which was also measured. There were also differences in root and stem H isotope ratios (up to 17) in 67% of samples, although the difference was only significant in shallow samples from the floodplain. The general similarity in stem and root ²H values indicates that most roots sampled were involved in the main supply of water to the canopy. Patterns of root function varied between the individual sites. Trees were primarily using groundwater at the floodplain and mountain front sites, as the surface soils had mean matric potentials of-1800 kPa. At the mountain front site, the surface roots were transporting groundwater to the canopy in isolation form the surrounding soil. In contrast, surface roots at the floodplain were taking up water from the surrounding soil, although this water was not a significant source in the trees' overall water supply. This activity of surface roots would not have been evident from the ²H data without the root samples. At the cold desert the roots in moist surface soil provided the main source of water for the shrubs. There too the root data indicated different water uptake patterns than otherwise would have been assumed. The root data showed that groundwater could not have been a water source, a conclusion which had been reached in a previous study. Thus measurements of stable isotope ratios in root water may be a valuable tool in assessing water uptake patterns and root function.     

Cyclic AMP induces rapid increases in gap junction permeability and changes in the cellular distribution of connexin43

The rapid effects of cAMP on gap junction-mediated intercellular communication were examined in several cell types which express different levels of the gap junction protein, connexin43 (Cx43), including immortalized rat hepatocyte and granulosa cells, bovine coronary venular endothelial cells, primary rat myometrial and equine uterine epithelial cells. Functional analysis of changes in junctional communication induced by 8-bromo-cAMP was monitored by a fluorescence recovery after photobleaching assay in subconfluent cultures in the presence or absence of 1.0 mm 1-octanol (an agent which uncouples cells by closing gap junction channels). Communicating cells treated with 1.0 mm 8-bromo-cAMP alone exhibited significant increases in the percent of fluorescence recovery which were detected within 1–3 min depending on cell type, and junctional communication remained significantly elevated for up to 24 hr. Addition of 1.0 mm 8-bromo-cAMP to cultured cells, which were uncoupled with 1.0 mm octanol for 1 min, exhibited partial restoration of gap junctional permeability beginning within 3–5 min. Identical treatments were performed on cultures that were subsequently processed for indirect immunofluorescence to monitor Cx43 distribution. The changes in junctional permeability of cells correlated with changes in the distribution of immunoreactive Cx43. Cells treated for 2 hr with 10 m monensin exhibited a reduced communication rate which was accompanied by increased vesicular cytoplasmic Cx43 staining and reduced punctate surface staining of junctional plaques. Addition of 1.0 mm 8-bromo-cAMP to these cultures had no effect on the rate of communication or the distribution of Cx43 compared to cultures treated with monensin alone. These data suggest that an effect of cyclic AMP on Cx43 gap junctions is to promote increases in gap junctional permeability by increasing trafficking and/or assembly of Cx43 to plasma membrane gap junctional plaques.We acknowledge the technical assistance of Richard Lewis and Meghan Abella. We thank Dr. Hugh Dookwah for contributions to the myometrial cell isolation protocol and Drs. Stephen H. Safe, Timothy D. Phillips, and Evelyn Tiffany-Castiglioni for helpful discussions. This work was funded by NIH (HD-26182, P42-ES04917, ES05871-01A1), the March of Dimes Birth Defects Foundation Basic Research grant #1-0796, and USDA 92-37203-7952.     

Structure of the histone tetramer (H3-H4)2: 2. Position of λmax in the tyrosyl fluorescence spectra and tyrosyl accessibility to quenchers

It was shown that the histone tetramer (H3-H4)₂ fluorescence spectra were shifted by about 2 nm towards the long-wave region and had a larger halfwidth than the free tyrosine fluorescence spectra. Denaturation with 8 m urea resulted in a shift towards the short-wave region and a decrease in the halfwidth of the histone tetramer (H3-H4)₂ tyrosine fluorescence spectra. Fluorescence quenching of the histone tetramer (H3-H4)₂ by iodine ions was analysed by the Stern-Volmer equation. It was estimated that at 0.1 m NaCl and 0.3–0.8 m NaCl, 45% and 60% tyrosyl fluorescence, respectively, was quenched by I^? ions. The results obtained suggests that histone tetramer (H3-H4)₂ may have several structural forms distinguished by the amount of ‘exposed’ and ‘buried’ tyrosyls depending upon the conditions of the medium.     

Fluorescence studies using synchrotron radiation on normal and differentiated cells labeled with parinaric acids

Changes in membrane properties during the differentiation process in K562 cells have been investigated. A decrease of lectin-induced agglutination has been detected. The agglutination assay revealed to be an early and sensitive test to monitor the induced differentiation of the K562 cells. Naturally occurring fluorescent fatty acids (cis- and trans-parinaric acids) and the recently developed multifrequency phase and modulation technique were used to study cell membrane properties. Changes in fluorescence lifetime and polarization are clearly associated with cell differentiation, suggesting the involvement of the cellular plasma membrane in the differentiation process.     

Effect of ligand binding and conformational changes in proteins on oxygen quenching and fluorescence depolarization of tryptophan residues

The rotational freedom of tryptophan residues in protein-ligand complexes was studied by measuring steady-state fluorescence anisotropies under conditions of oxygen quenching. There was a decrease in the oxygen bimolecular quenching constant upon complexation of trypsin and alpha-chymotrypsin with proteinaceous trypsin inhibitors, of lysozyme with N-acetylglucosamine (NAG) and di(N-acetyl-D-glucosamine) ((NAG)2) and of hexokinase with glucose. Binding of the bisubstrate analogue N-phosphonacetyl-L-aspartate (PALA) to aspartate transcarbamylase (ATCase) and binding of biotin to avidin resulted in increased oxygen quenching constants. The tryptophan of human serum albumin (HSA) in the F state was more accessible to oxygen quenching than that in the N state. With the exception of ATCase, the presence of subnanosecond motions of the tryptophan residues in all the proteins is suggested by the short apparent correlation times for fluorescence depolarization and by the low apparent anisotropies obtained by extrapolation to a lifetime of zero. Complex formation evidently resulted in more rigid structures in the case of trypsin, alpha-chymotrypsin and lysozyme. The effects of glucose binding on hexokinase were not significant. Binding of biotin to avidin resulted in a shorter correlation time for the tryptophan residues. The N --> F transition in HSA resulted in a more rigid environment for the tryptophan residue. Overall, these changes in the dynamics of the protein matrix and motional freedom of tryptophan residues due to complex formation and subsequent conformational changes are in the same direction as those observed by other techniques, especially hydrogen exchange. Significantly, the effects of complex formation on protein dynamics are variable. Among the limited number of cases we examined, the effects of complex formation were to increase, decrease or leave unchanged the apparent dynamics of the protein matrix.