Comparative karyomorphology and interrelationships ofSelaginella in Japan

Karyomorphological comparisons were made of 16 native and cultivated species ofSelaginella in Japan. The somatic chromosome numbers are 2n=16 inS. boninensis; 2n=18 inS. doederleinii, S. helvetica, S. limbata, S. lutchuensis, S. nipponica, S. selaginoides, S. tama-montana, andS. uncinata; 2n=20 inS. biformis, S. involvens, S. moellendorffii, S. remotifolia, andS. tamariscina; 2n=30 inS. rossii; and 2n=32 inS. heterostachys. The interphase nuclei of all species examined are uniformly assigned to the simple chromocenter type. The metaphase karyotype of 2n=16 (x=8) is 8 m (=median centromeric chromosomes)+8(st+t)(=subterminal and terminal). The group of the species having 2n=18 (x=9) is heterogeneous karyomorphologically: The karyotype ofS. nipponica is 2n=18=6 m+12(st+t),S. tama-montana 10 m+2 sm(=submedian)+6(st+t), andS. uncinata 6 m+7 sm+5(st+t). Although the remaining five species have the common karyotype 8 m+4 sm+6(st+t), the values of mean chromosome length are variable. Another group of the specles having 2n=20 (x=10) is homogeneous, since all species have the same karyotypes 8 m+4 sm+8(st+t) and have similar chromosome size. The karyotype of 2n=30 is 12 m+6 sm+12(st+t) and is suggested to be a triploid of x=10, and 2n=32=16m+16(st+t), a tetraploid of x=8. Thus, three kinds of basic chromosome numbers, x=8, 9, 10 are present in JapaneseSelaginella examined, and their karyomorphological relationships are discussed.     

Protonation,alkylation, addition and redox reactions of 16, 17 and 18 valence electron [Mo(L)(NO)('S4')] complexes [L = SPh,PMe3, NO; 'S4'2– = 1,2-Bis-(2-mercaptophenylthio)ethane(2-)]

In the quest for complexes modelling functional characteristics of metal sulfur oxidoreductases, a series of molybdenum nitrosyl complexes with sulfur-dominated coordination sphere was synthesized. Treatment of the 16, 17 and 18 valence electron (VE) complexes [Mo(L)(NO)('S₄')] (1–3) [L?=?SPh (1), PMe₃ (2), NO (3), 'S₄'^2–?=?1,2-bis-(2-mercaptophenylthio) ethane(2-)] with the Brönsted acid HBF₄ resulted in formation of different types of products. 1 and 3 were reversibly protonated at one thiolate atom of the 'S₄'^2– ligand;2, however, yielded the phosphonium salt [HPMe₃]BF₄ and the dinuclear [Mo(NO)('S₄')]₂. Alkylation of 1, 2 and 3 by Me₃OBF₄ or Et₃OBF₄ uniformly resulted in high yields of [Mo(L)(NO)(R-'S₄')]BF₄ complexes [L?=?SPh: R?=?Me (5), Et (6); L?=?PMe₃: R?=?Me (7); L?=?NO: R?=?Me (8), Et (9)] in which one thiolate atom of the 'S₄'^2– ligand had become alkylated; the NMR spectra of 5, 6, 8 and 9 indicated that only one out of four theoretically possible diastereoisomers had formed. 5 and 6 were characterized also by single-crystal X-ray structure analyses. A comparison of ν(NO) bands and redox potentials (cyclic voltammetry) of parent complexes and alkylated derivatives showed that alkylation leads to a decrease in electron density at the molybdenum center and to a positive shift in redox potentials. The 16 VE complex 1 could be reduced, also chemically, to give the corresponding 17 VE anion [1]^–, and inserted elemental sulfur into the Mo-SPh bond, forming the 18 VE phenylperthio complex [Mo(η²–SSPh)(NO)('S₄')] (11) which, upon reaction with PPh₃, gave SPPh₃ and regenerated the parent complex 1. These results are discussed with regard to the sequence of proton and electron transfer steps occurring in substrate conversions catalyzed by metal sulfur oxidoreductases.     

Dynamic properties of the advertisement calls of gray tree frogs: patterns of variability and female choice

We assessed the potential for several acoustic properties ofthe advertisement calls of male gray tree frogs to affect relativemating success by relating patterns of variation in these propertiesto minimum differences required to elicit female choice. Dynamicproperties (pulse number, PN; call rate, CR; and duty cycle,DC, the ratio of call duration to call period) varied much morewithin bouts of calling than a static property (dominant frequency,DF) but nevertheless exhibited significant between male variationin three of four breeding seasons. Many multiply recorded malesconsistently produced calls with values substantially aboveor below mean values of males recorded on the same nights. Nightlyranges of variation in PN and CR were often greater than theminimum differences required to elicit female preferences inthe laboratory. In most experiments, females chose high-PN orfast-CR calls over low-PN or slow-CR alternatives, respectively,even if the preferred stimuli were farther away or 6-10 dB lowerin sound pressure level (SPL), provided that differences inPN or CR were 100%. Consistent with these results, females didnot always choose the closer of two calling males in the field.Nightly ranges of variation in DF rarely equaled the minimumdifference required to elicit SPL independent preferences. Femalespreferred a stimulus of high-PN and slow-CR over an alternativeof low-PN or fast-CR with the same acoustic on-time; in twoexperiments, females chose calls of high-PN over low-PN alternativeseven though the playback of the high-PN call was interruptedand the low-PN call was broadcast continuously. Thus, femalepreferences were not merely based on the total time of acousticstimulation. Responses of females tested twice in the same experimentsuggest that phenotypic variation in preference was limitedin our study populations.     

Radiative properties of hardwood leaves to ultraviolet irradiation

Spectral reflectance and transmittance of leaves to ultraviolet irradiation were determined under laboratory conditions for seven species of hardwood trees, namely red oak (Quercus rubra, L), black oak (Q. velutina, Lamarch), white oak (Q. alba, L.), sugar maple (Acer saccharum), Norway maple (A. plantanoides), hickory (Carya tomemtosa), sweetgum (Liquidambar styraciflua), and black oak litter. The experimental system consisted of a solar simulator, an integrating sphere, and a spectroradiometer. Experiments were repeated three to five times for both adaxial and abaxial surfaces of fresh leaves chosen at randomly. The spectral distributions and simple averages of the radiative properties in the wavelength ranges of ultraviolet-B (UV-B, 280–320 nm) and ultraviolet-A (UV-A, 320–400 nm) were determined. The spectral distributions of reflectance were similar between adaxial and abaxial surfaces, although the magnitude varied among tree species. Leaf reflectance was very low for the ultraviolet spectrum in general and varied among species and between adaxial and abaxial surfaces. It was generally higher over the UV-A waveband compared to UV-B, and higher on the abaxial than adaxial surface. The broadband reflectance in the UV-A range (over all species) was 5.0 and 3.9% for abaxial and adaxial surface, respectively, compared to 3.5 and 2.8% in UV-B. The transmittance through leaves was extremely small in the UV-B (<0.1%) and nearly zero in the UV-A spectral range. Consequently, the absorptance of ultraviolet radiation by leaves, as determined from the measured reflectance and transmittance, was quite high, being more than 90% for all the combinations of species and wavebands examined. The reported results are useful for studies requiring spectral radiative properties of the examined leaves with respect to ultraviolet irradiation.     

Expression of Biologically Active Basic Fibroblast Growth Factor by Genetically Modified Rat Primary Skin Fibroblasts

Abstract: Basic fibroblast growth factor (FGF-2) is normally expressed as a cell-associated protein, and accordingly it is not clear how it exerts its action on target cells in vivo. It has been proposed that cells release, by death or other mechanisms, small amounts of FGF-2 that then acts in an autocrine manner. To address the question of whether it is necessary that FGF-2 remain cell associated or needs to be secreted from cells to have biological activity, we expressed the 18-kDa form of FGF-2 in primary fibroblasts as a cell-associated (FGF-2-B) or as a secreted (FGF-2-S) protein. FGF-2 protein is detected in cell lysates and membrane fractions of both cell types, whereas it is present in significant amounts only in the conditioned medium of FGF-2-S cells. No FGF-2 is detected in control (untransfected) cells. FGF-2-S cells also grow faster than the control or FGF-2-B cells. Yet, when evaluated for their ability to promote the survival of embryonic hippocampal neurons in vitro, both the cell types are active, establishing the activity of the transgene product. We conclude that FGF-2 is active when engineered to be expressed as a cell-associated form or secreted from cells.     

Leaf characteristics and optical properties of different woody species

 Light partition has been examined and evaluated on five woody species (Olea europaea, Ficus carica, Pittosporum tobira, Hedera helix maculata, Persica vulgaris) in relation to their leaf morpho-histological characteristics, water and chlorophyll contents. Leaf parameters and optical properties (reflectance, transmittance, absorbance) in PAR, FR and NIR wavebands (400–1100 nm) were preliminarily submitted to a canonical correlation analysis where lamina thickness and water content showed a leading role in determining all the optical properties, while chlorophyll, influential in the PAR region, was remarkably effective only in an extreme pigment situation when green and albino patches of ivy leaves were compared. Transmittance appeared inversely related to lamina thickness in accordance with the Lambert Beer law. Significant correlations were found also between mesophyll water content and both transmittance (positive) and reflectance (negative). Olive leaves showed peculiar optical patterns because of the dense and continuous trichome layer on their abaxial surface. Received: 3 January 1997 / Accepted: 5 May 1997     

Structure characterization of the central repetitive domain of high molecular weight gluten proteins. II. Characterization in solution and in the dry state.

The structure of the central repetitive domain of high molecular weight HMW) wheat gluten proteins was characterized in solution and in the dry state using HMW proteins Bx6 and Bx7 and a subcloned, bacterially expressed part of the repetitive domain of HMW Dx5. Model studies of the HMW consensus peptides PGQGQQ and GYYPTSPQQ formed the basis for the data analysis (van Dijk AA et al., 1997, Protein Sci 6:637-648). In solution, the repetitive domain contained a continuous nonoverlapping series of both type I and type II II beta-turns at positions predicted from the model studies; type II beta-turns occurred at QPGQ and QQGY sequences and type I beta-turns at YPTS and SPQQ. The subcloned part of the HMW Dx5 repetitive domain sometimes migrated as two bands on SDS-PAGE; we present evidence that this may be caused by a single amino acid insertion that disturbs the regular structure of beta-turns. The type I beta-turns are lost when the protein is dried on a solid surface, probably by conversion to type II beta-turns. The homogeneous type II beta-turn distribution is compatible with the formation of a beta-spiral structure, which provides the protein with elastic properties. The beta-turns and thus the beta-spiral are stabilized by hydrogen bonds within and between turns. Reformation of this hydrogen bonding network after, e.g., mechanical disruption may be important for the elastic properties of gluten proteins.     

Quantification and correlation of vesicular-arbuscular mycorrhizal propagules with soil properties of some mollisols of northern India

The populations of vesicular-arbuscular mycorrhizae (VAM) propagules by the most probable number method in some mollisols and their correlations with some important soil properties were determined. On average, the six soils, Phoolbagh clay loam, Beni silty clay loam, Haldi loam, Nagla loam, Khamia sandy loam and Patherchatta sandy loam contained 4.9, 4.0, 7.9, 7.9, 3.3 and 13.0 propagules/g soil, respectively, i.e. none of the soils was found to be high in VAM. The size of the VAM population was compared to soil properties such as pH, organic carbon, sand content, available phosphorus and available potassium, cation-exchange capacity, silt and clay contents. A significant positive correlation (r=0.586) was only found with available soil phosphorus (P<0.05) and a significant negative correlation (r=-0.555) with soil clay content (P<0.05).Directorate research paper series No. 7862     

Physico-chemical properties and evidence for electrophoretic variants of rat transcortin

Isolation of rat plasma transcortin was carried out by affinity chromatography, as previously described for human. The protein was shown to be pure by PAGE and one single N-terminal amino acid was identified (Ser), which suggested that the protein molecule has a single polypeptide chain. This assumption is supported by SDS-PAGE. The amino acid composition was reported and compared with the one of human transcortin. The purified protein always migrated in PAGE (with or without SDS) as a double band; the faster component being more intense than the slower one. Whether transcortin was free or bound to corticosterone, the same aspect was observed. Molecular weight of these two variants were determined by SDS-PAGE as 65,900 and 75,800. Polymers only appeared after irreversible denaturation of the protein, as previously described for human transcortin. Various other physical parameters were determined: a sedimentation coefficient of 3.71 S +/- 0.18 was calculated by ultracentrifugation in sucrose gradient, association constants at 4 degrees C for corticosterone and cortisol (2.7 X 10(9) M-1 and 4.2 X 10(8) M-1, respectively).     

Comparison of chemical properties of purified plasma membranes and secretory vesicle membranes from the bovine adrenal medulla

Summary A highly enriched fraction of plasma membranes from the bovine adrenal medulla has been isolated by differential and sucrose gradient centrifugation. The membranes were found to occur as 0.1–0.5 diameter vesicles and to equilibrate at a density of 1.13–1.14 g/ml. This fraction was characterized by 4-fold elevated levels of adenylate cyclase and 20-fold elevated levels of 5-nucleotidase. Secretory vesicle membranes, isolated by repeated hypotonie and hypertonic shocks of whole vesicles, were found to equilibrate between d = 1.08 and d = 1.12 on a sucrose density step gradient. These membranes were highly enriched in cytochrome b₅₆₂ and dopamine--hydroxylase. Proteins in the two membranes were compared by SDS gel electrophoresis. All protein size classes found in the vesicle membrane fraction were also represented in the plasma membrane fraction, though in different proportions on the basis of staining intensity. The plasma membrane fraction contained prominent bands co-migrating with the - and -bands of tubulin, as well as a component co-migrating with actin. These bands were absent from the vesicle membranes. Fingerprint analysis of stained bands from the membrane fraction demonstrated that the components were indeed tubulin and actin. The plasma membranes contained twice as much sialic acid residues as did the chromaffin granule membranes, but had only half the cholesterol content on a weight basis. The cholesterolphospholipid ratio in the plasma membranes was 0.63, while in the secretory vesicle membranes it was 1.04. These results show that plasma membranes and secretory vesicle membranes are functionally and structurally different.Supported, in part, by a stipend to O.Z. from The Grant Foundation, New York