bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular vibrational energy flow and dilution factors in an anharmonic state space
Authors: Sibert Edwin L. , Gruebele Martin
Published: January 2006

A fourth-order resonance Hamiltonian is derived from the experimental normal-mode Hamiltonian of SCCl2. The anharmonic vibrational state space constructed from the effective Hamiltonian provides a realistic model for vibrational energy flow from bright states accessible by pulsed laser excitation. We study the experimentally derived distribution PE(σ) of dilution factors σ as a function of energy. This distribution characterizes the dynamics in the long-time limit. State space models predict that PE(σ) should be bimodal, with some states undergoing facile intramolecular vibrational energy redistribution (small σ), while others at the same total energy remain “protected” (σ≈1). The bimodal distribution is in qualitative agreement with analytical and numerical local density of states models. However, there are fewer states protected from energy flow, and the protected states begin to fragment at higher energy, shifting from σ≈1 to σ≈0.5. We also examine how dilution factors are distributed in the vibrational state space of SCCl2 and how the power law specifying the survival probability of harmonic initial states correlates with the dilution factor distribution of anharmonic initial states.
Neoclassical polarization drift of collisionless single ions in a sheared radial electric field in a tokamak magnetic geometry
Authors: Baek Hoyul , Ku Seunghoe , Chang C. S.
Published: January 2006

Neoclassical polarization drift is known to play critical role in the dynamical behavior of a sheared radial electric field Er in a toroidal confinement device. However, basic studies on the effect of radial electric shear on neoclassical polarization drift have not yet appeared in the literature. In the present report, the neoclassical polarization drift speed VNP of collisionless single ions is studied using a guiding-center code in a time-varying, spatially sheared Er in a realistic tokamak geometry. It is found numerically that the VNP for single ions is not only a function of the time derivative ∂Er∕∂t, but also a strong function of the radial shear Δr∂Er∕∂r if the shear length is on the same order as the ion banana width Δr. Comparison with an analytic investigation reveals that this effect is simply due to the finite banana modification to the orbital average Er. An approximate analytic formula has been presented for collisionless single banana ions in a conventional tokamak magnetic geometry. The trapped-passing boundary layer physics is not treated.
The approximation of the transmutation kernel
Authors: Boumenir Amin
Published: January 2006

The transformation operator plays an important role in the direct and inverse spectral theory of Sturm-Liouville operators. In this paper we would like to approximate the kernel of the transformation operator used in the Gelfand-Levitan theory. The analytic properties of the solution allows for its representation by either a Taylor series about the diagonal or a Fourier cosine series. Example illustrating how the coefficients can be computed are provided.
Fermi-level depinning for low-barrier Schottky source/drain transistors
Authors: Connelly Daniel , Faulkner Carl , Clifton P. A. , Grupp D. E.
Published: January 2006

By imposing an ultrathin insulator between low-work function metals and silicon, the Schottky barrier of the junction can be substantially reduced, decreasing junction resistance. With this approach, low-Schottky-barrier metal source/drain (S/D) transistors with Mg and Yb as S/D metals are demonstrated.
Ferromagnetic FeSe: Structural, electrical, and magnetic properties
Authors: Feng Q. J. , Shen D. Z. , Zhang J. Y. , Li B. S. , Li B. H. , Lu Y. M. , Fan X. W. , Liang H. W.
Published: January 2006

FeSe thin films were grown on GaAs (001) substrates using low-pressure metalorganic chemical vapor deposition. X-ray diffraction analysis showed that FeSe thin films were in tetragonal structure with (002) orientation. It was found that the FeSe thin films were ferromagnetic above room temperature, revealing a maximum saturation magnetization about 590emu∕cc along the in-plane magnetic easy axis. The Hall measurement indicated that the as grown FeSe thin films was of p-type conduction with hole concentration of as high as 1020∼1021cm−3. The magnetic circular dichroism spectrum was employed to study the electronic structure.
Low-temperature synthesis of (Pb,La)(Zr,Ti)O3 thick film on Ti substrates by the hydrothermal method using oxide precursors
Authors: Chen Xiuli , Fan Huiqing , Ke Shanming
Published: January 2006

We simplified the hydrothermal process using oxides instead of liquid-base reactants as precursors. Lead lanthanum zirconate titanate Pb0.94La0.06(Zr0.65Ti0.35)0.985O3 (PLZT) thick films were prepared on Ti substrates at 150°C via hydrothermal synthesis. The films with a single perovskite structure were smooth and the surfaces were free of micrometer scale cracks. The thickness of the film was about 56μm. The dielectric constant and dielectric loss were 665 and 0.03, respectively, at 1MHz. Even at high frequencies the dielectric properties of the PLZT film still remain stable. The samples showed excellent reproducibility in the measurement of leakage current.
Adatom-assisted structural transformations of fullerenes
Authors: Lee In-Ho , Jun Sukky , Kim Hanchul , Kim Sung Youb , Lee Youngmin
Published: January 2006

Microscopic mechanism of autocatalytic structural transformations of fullerenes is investigated by the action-derived molecular dynamics. Dynamic pathways and the corresponding activation energies are obtained for the Stone-Wales transformation in fullerene and the fullerene coalescence, under the presence of extra carbon atoms. The adatom-assisted Stone-Wales transformation is proved to be a highly probable process unit for the structural transformations and annealing treatments of carbon-based graphitic networks. The complex processes of adatom-assisted fullerene coalescence, yielding very low activation energies, are presented.
Epitaxy of nonpolar AlN on 4H-SiC (1-100) substrates
Authors: Armitage R. , Suda J. , Kimoto T.
Published: January 2006

AlN has been grown on 4H-SiC (1-100) substrates by rf-plasma molecular beam epitaxy. The epilayers assume a metastable 4H structure to match the in-plane stacking arrangement of the substrate. Initial two-dimensional nucleation of 4H-AlN is revealed by reflection high-energy electron diffraction. The epitaxial quality is evidenced by narrow x-ray diffraction ω-scan linewidths less than 70 arcsec for both symmetric and asymmetric reflections. The AlN growth surface exhibits a smooth and anisotropic morphology similar to that of GaN (1-100). Large residual stress is present in the epilayers, consistent with incomplete relaxation of misfit strain during growth.
Visualizing the transient electroosmotic flow and measuring the zeta potential of microchannels with a micro-PIV technique
Authors: Yan Deguang , Nguyen Nam-Trung , Yang Chun , Huang Xiaoyang
Published: January 2006

We have demonstrated a transient micro particle image velocimetry (micro-PIV) technique to measure the temporal development of electroosmotic flow in microchannels. Synchronization of different trigger signals for the laser, the CCD camera, and the high-voltage switch makes this measurement possible with a conventional micro-PIV setup. Using the transient micro-PIV technique, we have further proposed a method on the basis of inertial decoupling between the particle electrophoretic motion and the fluid electroosmotic flow to determine the electrophoretic component in the particle velocity and the zeta potential of the channel wall. It is shown that using the measured zeta potentials, the theoretical predictions agree well with the transient response of the electroosmotic velocities measured in this work.
Change in cation nonstoichiometry at interfaces during crystal growth in polycrystalline BaTiO3
Authors: Choi Si-Young , Kang Suk-Joong L. , Chung Sung-Yoon , Yamamoto Takahisa , Ikuhara Yuichi
Published: January 2006

Using an embedded single crystal in a polycrystalline matrix and quantitative electron energy loss spectroscopy, we have demonstrated that Ti-excess grain boundary nonstoichiometry can vary with the extent of boundary migration. While a slight excess in Ti was detected at the boundaries between small matrix grains, a large increase in Ti∕Ba ratio, to as much as ∼1.50 compared to the stoichiometric value, was present at the interface between a growing single crystal and the matrix grains when the embedded crystal grew up to a few hundred micrometers. This change in nonstoichiometry was attributed to a continuous accumulation of excessive Ti at the moving boundary during crystal growth. The present result indicates that growth kinetics can critically affect the interface chemistry in polycrystals.
Kinetics of strain relaxation in Si1−xGex thin films on Si(100) substrates: Modeling and comparison with experiments
Authors: Kolluri Kedarnath , Zepeda-Ruiz Luis A. , Murthy Cheruvu S. , Maroudas Dimitrios
Published: January 2006

We report the results of a theoretical analysis for the kinetics of strain relaxation in Si1−xGex thin films grown epitaxially on Si(100) substrates. The analysis is based on a properly parametrized dislocation mean-field theoretical model describing plastic deformation dynamics due to threading dislocation propagation and addresses strain relaxation kinetics during both epitaxial growth and thermal annealing, including post-implantation annealing. Theoretical predictions for strain relaxation as a function of film thickness in Si0.80Ge0.20∕Si(100) samples annealed after epitaxial growth either unimplanted or after He ion implantation are in excellent agreement with experimental measurements [J. Cai et al., J. Appl. Phys. 95, 5347 (2004)].
Nonmonotonic ferromagnetic thickness dependence of out-of-plane interlayer coupling between two Co∕Pt multilayers across a 11 Å NiO spacer
Authors: Liu Z. Y. , He J. L. , Tian Y. J. , Yu G. H. , Jiang Y.
Published: January 2006

In [Pt(5Å)∕Co(tCoÅ)]3∕NiO(11Å)∕[Co(tCoÅ)∕Pt(5Å)]3 multilayers, the out-of-plane antiferromagnetic interlayer coupling between the Co∕Pt multilayers can be tailored via varying the Co layer thickness tCo. The coupling strength increases with increase of tCo, but after reaching a maximum at tCo=4.5Å, it decreases with further increase of tCo. At tCo>6Å, no out-of-plane antiferromagnetic interlayer coupling has been observed. This nonmonotonic dependence on tCo of the coupling strength can be attributed to variation of the out-of-plane effective magnetic anisotropy in Co∕Pt multilayers with tCo.
Surface passivation properties of boron-doped plasma-enhanced chemical vapor deposited hydrogenated amorphous silicon films on p-type crystalline Si substrates
Authors: De Wolf Stefaan , Beaucarne Guy
Published: January 2006

Heterostructures, such as the crystalline silicon (c-Si)/plasma-enhanced chemical vapor deposited (PECVD) hydrogenated amorphous silicon (a-Si:H) structure, form a possibility in the development of a low recombination rear contact for photovoltaic devices fabricated from p-type c-Si(p) substrates. To find a good compromise between limited charge carrier recombination at the surface and a limited resistivity of the contact, a sandwich structure, such as c-Si(p)∕a-Si:H(i)∕a-Si:H(p+) has been proposed in the past. However, in this letter, we report that whereas a very thin intrinsic a-Si:H layer (∼3nm) may still yield very low values for the surface recombination velocity of low resistivity (0.5–1.5Ωcm) c-Si(p) wafers, the surface passivation properties are lost when this intrinsic film is subsequently covered by a PECVD a-Si:H(p+) layer. This phenomenon suggests that surface recombination does not take place at the c-Si(p)∕a-Si:H(i) interface, but more likely in the defect-rich PECVD a-Si:H(p+) material, by tunneling of minority carriers through the thin a-Si:H(i) layer.
The heterogeneity of turnip-tops (Brassica rapa) seeds inside the silique affects germination, the activity of the final step of the ethylene pathway, and abscisic acid and polyamine content
Authors: Puga-Hermida María Isabel , Gallardo Mercedes , Rodríguez-Gacio María del Carmen , Matilla Angel J.
Published: January 2006

The mature silique of turnip-tops (Brassica rapa L. cv. Rapa) contains seeds that are heterogeneous in colour. From these seeds, we have selected three homogeneous lots: black (B), dark brown (DB) and light brown (LB). The dry seeds of these lots contained different levels of free and conjugated 1-aminocyclopropane-1-carboxylic acid (ACC), polyamines (PA) and ABA, the levels of the latter being inversely related to the germinative capacity. The water uptake (WU) rate was much faster in LB seeds than in B. This fact was probably related to the breaking of the seed coat, the speed of which was B >> DB > LB. The ABA, spermidine (Spd) and spermine (Spm) contents decreased in the seeds during germination, whereas the putrescine (Put) levels rose sharply (B > DB > LB). For the first time in seeds, heterogeneity is reported with respect to ethylene sensitivity and synthesis. Whereas exogenous ethylene did not alter the percentage of germination in lot B, germination was higher in DB and LB (LB�>> DB) in the presence of ethylene. The final step of the ethylene pathway was altered concomitantly with this change in germinating capacity, affecting the levels of 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), ACC, ACC–oxidase (ACO) and ethylene production. The gene BrACO1, recently characterised by us, is expressed differently in the three seed lots, particularly in the LB, where little transcription occurs. Finally, ethylene inhibits Put, Spd and Spm levels at different intensities in the three lots. The results point towards variation in the channelling of ACC towards synthesis of ethylene and / or PA, caused by the heterogeneity.
Stabilization of the oxygen-evolving complex of photosystem II bybicarbonate and glycinebetaine in thylakoid and subthylakoidpreparations
Authors: Klimov Vyacheslav V. , Allakhverdiev Suleyman I. , Nishiyama Yoshitaka , Khorobrykh AndreiA. , Murata Norio
Published: January 2006

The protective effect of 1 M glycinebetaine on thermal inactivation of photosynthetic oxygen evolution in isolated photosystem II membrane fragments from spinach is observed in CO2-free medium in both the presence and absence of added 2 mM bicarbonate. Conversely, the protective effect of 2 mM bicarbonate against thermoinactivation is seen in the absence as well as in the presence of 1 M glycinebetaine. The stabilizing effect of bicarbonate is also observed in thylakoid membranes from Synechococcus sp. PCC 7002 treated with 0.1% Triton X-100, and in unbroken spinach thylakoids. It is shown for the first time that bicarbonate protects the water-oxidizing complex against inactivation induced by pre-incubation of photosystem II membrane fragments (25°C) and thylakoids (40°C) at low pH (5.0–5.5) in non-bicarbonate-depleted medium. We conclude that the protective effects of glycinebetaine and bicarbonate are of a different nature; glycinebetaine acts as a non-specific, compatible, zwitterionic osmolyte while bicarbonate is considered an essential constituent of the water-oxidizing complex of photosystem II, important for its functioning and stabilization.
A grapevine TFL1 homologue can delay flowering and alter floral development when overexpressed in heterologous species
Authors: Boss Paul K. , Sreekantan Lekha , Thomas Mark R.
Published: January 2006

Grapevines (Vitis vinifera L.) have unusual plant architecture in that the shoot apical meristem produces both vegetative structures and primordia that are capable of forming inflorescences at regular intervals. These primordia are termed ‘uncommitted’ and differentiate into inflorescences or tendrils depending on the environment in which they are produced. To investigate the molecular relationship between tendrils and inflorescences and vine architecture, we cloned a TFL1 homologue from grapevine (VvTFL1). VvTFL1 is expressed in shoot apices early in latent bud development and in buds soon after bud burst. The grapevine homologue of LEAFY, VFL, is expressed at the same stages as VvTFL1 as well as in the later stages of inflorescence development. Neither VvTFL1 nor VFL were detected in tendrils. VvTFL1 was overexpressed in tobacco and Arabidopsis to confirm that it was functionally similar to TFL1 and not the close homologue FT. Flowering was delayed significantly in tobacco and Arabidopsis transformants overexpressing VvTFL1. However, an unexpected phenotype was observed in some of the transgenic Arabidopsis lines where the floral meristem became indeterminate and a new inflorescence would emerge from within the developing silique. Our findings suggest that VvTFL1 is a repressor of floral development. The nucleotide sequence reported in this paper has been submitted to GenBank under the accession number AF378127 (VvTFL1).
The first cycad-associated thrips in the family Phlaeothripidae, Stomothrips cycasi, gen. et sp. nov. (Thysanoptera)
Authors: Okajima Shûji
Published: January 2006

A new genus and species of phlaeothripine Thysanoptera,
Stomothrips cycasi, is described from
Cycas calcicola in the Northern Territory, Australia.
This cycad has a restricted distribution, and at the collecting site the
fronds were turning brown, apparently due to a fungal infection. The thrips,
which have a remarkably long mouth-cone, probably feed on the fungus rather
than the cycad tissue.
Review of the hyperiidean amphipod genus Oxycephalus Milne-Edwards (Crustacea:Amphipoda: Hyperiidea:Oxycephalidae)
Authors: Zeidler Wolfgang
Published: January 2006

A taxonomic review of the genus Oxycephalusis provided
with a key to species. Only three species are recognised in this
review:O.piscatorMilne-Edwards, 1830,
O.latirostris Claus, 1879 and
O.clausi Bovallius, 1887. The systematic limits of these
three species are redefined and clarified and all species are illustrated.
O.longipes Spandl, 1927 is shown to be the female form
of O.latirostris and is consequently synonymised with
it. Appendices are provided listing species of indeterminable status (due to
loss of type material and inadequate description), species described as
Oxycephalusbut since transferred to other genera, and
species thought to belong to Oxycephalus in the past.
Revision of the New Zealand endemic eulophid genus Zealachertus Bouček (Hymenoptera : Chalcidoidea)
Authors: Berry Jocelyn A.
Published: January 2006

The New Zealand endemic eulophid genus ZealachertusBouček, 1978 is revised. The type species,Z. nothofagi Bouček, 1978 is redescribed andeleven new species are described: Z. abbreviatus, sp.nov., Z. aspirensis, sp. nov.,Z. bildiri, sp. nov., Z. binarius,sp. nov., Z. conjunctus, sp. nov.,Z. holderi, sp. nov., Z. longus,sp. nov., Z. nephelion, sp. nov.,Z. pilifer, sp. nov., Z. planus,sp. nov., and Z. tortriciphaga, sp. nov. A key tospecies is provided, with additional diagnostic features for each species.Generic relationships, host records and biogeography are discussed. Acladistic analysis is undertaken to determine relationships within the genususing two species of Diaulomorpha Ashmead, 1900 asoutgroup taxa.
Two novel chromosomal loci influence cultivar-specific nodulation failure in the interaction between strain ANU794 and subterranean clover cv. Woogenellup
Authors: Roddam Louise F. , Lewis-Henderson Wendy R. , Djordjevic Michael A.
Published: January 2006

The nodulation failure resulting from the interaction between
Rhizobium leguminosarum biovar
trifolii strain ANU794 and the
Trifolium subterraneum cv. Woogenellup was examined by
transposon mutagenesis to resolve whether multiple determinants were involved
in cultivar-specificity. Three new transposon-induced mutants of ANU794 (W72,
W78 and W710) with significantly enhanced nodulation ability on cv.
Woogenellup were identified. The W72 and W78 mutations are
chromosomally-located, whereas the W710 mutation isplasmid-located. The
ethylene synthesis inhibitor, aminoethoxyvinylglycine, fails to enhance the
nodulation ability of ANU794, ANU7943 (csn1::Tn5) and
W78 on cv. Woogenellup, but enhances the nodulation ability of W72,W710 and
ANU7941 (nodM::Tn5). DNA sequencing of the W78 locus
reveals strong homology to an unknown Mycobacterium open
reading frame, and to several bacterial non-haem chloroperoxidases. The
previously identified csn1 locus showed homology to the
50S ribosomal protein, L9, with the Tn5 insertion being located in the
5′-untranslated region. The results suggest that cultivar-specificity is
mediated by at least two independent mechanisms or determinants, and not by a
simple gene-for-gene interaction. The role of ethylene in cultivar specificity
is discussed. Cultivar-specific interactions may prove useful in identifying
pathways involved in efficient nodule formation and plant-microbe
interactions.
Water import in the young tomato fruit limited by pedicel resistance and calyx transpiration
Authors: Bussières Philippe
Published: January 2006

Approximately 3 weeks after pollination, the water import rate per unit tomato
fruit area generally decreases linearly with fruit radius. In order to explain
why, in the first 3 weeks, the water import rate of the fruit is lower than
predicted by this regression, a model of water flow through the pedicel and a
model of water import based on the potential of water entering the fruit and
calyx transpiration were formulated. Using data sets available in the
literature, these models predict a water potential drop along the pedicel that
decreases sharply during the first 3 weeks, while the calculated hydraulic
conductivity of the pedicel phloem, which is presumed to be the main pathway
of the water imported in the tomato fruit, increases sharply in the lower
range of values known for plant phloem conductivity. These models also predict
an increase in water import into young fruit when calyx transpiration is
decreased, which is consistent with data from the literature. In order to
explain the increasing pedicel phloem conductivity, a model of water flow in
the pedicel sieve tubes was formulated based on the literature data for the
fruit stalk of Lupinus albus. It was suggested that the
conductivity might increase because of the development of pores in the sieve
plates. Using this hypothesis, the increase in pore radius values within an
acceptable range was calculated. This study shows that, under a wide range of
conditions, water import in young tomato fruit is limited by the low potential
of the water entering the fruit due to pedicel resistance and calyx
transpiration. It provides a model to predict young tomato fruit expansion and
a testable hypothesis, which can be checked by measuring the size of the
phloem component in the fruit pedicel.
Effects of elicitors and Ca2+ deprivation on the levels of sterols and 1α,25-dihydroxy vitamin D3 in cell cultures of Solanum malacoxylon
Authors: Burlini Nedda , Bernasconi Silvana , Manzocchi Lucia A.
Published: January 2006

1α,25-dihydroxy vitamin D3
[1α,25(OH)2D3],
the hormonal form of vitamin D3 that is essential for
the maintenance of calcium–phosphorus homeostasis in birds and mammals,
has been found in several plants. In order to study the metabolic role of
1α,25(OH)2D3 in plant cells,
we monitored the changes of cellular levels of
1α,25(OH)2D3 in cell
suspension cultures of Solanum malacoxylon Sendt. under
different experimental conditions. We also measured the levels of cholesterol,
the assumed precursor of vitamin D3, and other
end-product sterols such as β-sitosterol, stigmasterol and campesterol.
It was found that when cells are incubated in a calcium-deprived medium, the
level of 1α,25(OH)2D3
increases markedly within a few hours. Treatment with methyl jasmonate (MeJ),
a linolenic acid-derived compound that accumulates during wounding stress, was
found to reduce the cellular level of
1α,25(OH)2D3 and to promote
its secretion into the culture medium. After treatment with cellulysin, a
cellulase of fungal origin, the metabolite was no longer detectable, either in
the medium or in the cells. Calcium deprivation in the medium and treatment
with the elicitors MeJ and cellulase lowered the cellular level of all the
sterols tested. The possible role of
1α,25(OH)2D3 is discussed in
light of these results.
Corrigendum to: Floating row covers affect the molybdenum and nitrogen status of Chinese cabbage grown under field conditions
Authors: Moreno Diego A. , Víllora Gemma , Soriano Maria T. , Castilla Nicolas , Romero Luis
Published: January 2006

In three consecutive years of field experiments, an uncovered control
(T0), and floating row covers treatment
(T1: perforated polyethylene, 50 μm;
T2: polypropylene, 17 g m–2)
were used to produce different growth conditions for Chinese cabbage
[Brassica pekinensis (Lour) Rupr. cv. Nagaoka
50]. Five samplings (whole tops) were made between transplant and
harvest, and measurements were made of
NO3-,
NH4+. organic N, and Mo
concentrations, as well as nitrate reductase (NR) activity, and amino acids in
the whole shoots. The microclimatic conditions in T0
resulted in plants with higher Mo accumulation, as well as the highest basal
NR activity and the lowest NO3-
concentrations. The thermal environment under the T1
treatment induced the highest mean temperature values and resulted in plants
with the highest amino acid level, whereas the plants in the
T2 treatment with its intermediate thermal conditions,
had the lowest levels of Mo and the highest
NO3- concentrations. The floating
row covers influenced the Mo status, which in turn affected NR activity. In
addition, T1-polyethylene sheet and
T2fleece favoured an increase in the levels of
NO3- by the limitation in the NR
activity, with the consequent risk of a high NO
3- level in vegetables for human
consumption.
An iAc/Ds gene and enhancer trapping system for insertional mutagenesis in rice
Authors: Upadhyaya Narayana M. , Zhou Xue-Rong , Zhu Qian-Hao , Ramm Kerrie , Wu Limin , Eamens Andrew , Sivakumar Ramani , Kato Tsuneo , Yun Dow-Won , Santhoshkumar Chellian , Narayanan Kottaram K. , Peacock James W. , Dennis Elizabeth S.
Published: January 2006

We evaluated a two-component transposon iAc/Ds system
for generating a library of insertional mutants in rice. The constructs used
have gene or enhancer trapping properties, plasmid rescue and
T-DNA/Ds launching pad reporter facilities.
Mutagenic iAc/Ds lines were produced by three
methods: crossing iAc and Ds
containing lines; co-transformation with iAc and
Ds constructs; and super-transformation of
iAc transgenic calli with Ds
constructs. First and second generation screening populations, derived from
crosses (F2 and F3) or double
transformation (DtT1 and DtT2),
were analysed for stable insertion lines containing Ds
transposed to locations unlinked to iAc. The average
frequencies of putative stable insertion (PSI) lines in the
F2, DtT1,
F3 and DtT2 populations were 6.61,
5.58, 11.47 and 7.05% respectively, with large variations in these
frequencies in screening populations derived from different mutagenic lines.
Further analyses indicated that 41, 33, 65 and 64% of the PSI lines,
respectively, have Ds transposed to locations unlinked
to the original Ds launching pad. Using the plasmid
rescue system, sequences flanking Ds from 137 PSI lines
were obtained. Sixty-eight of these lines had unique insertions in genomic
regions, of which 18 were known sequences. Because the average frequency of
proven stable insertion lines in any of our screening populations has been
less than 5%, we suggest that additional features should be
incorporated in this two-component iAc/Ds system to
increase the screening efficiency, and to make it suitable for large-scale
insertional mutagenesis and determination of gene function in rice.
Acidic Growth Inhibitors From Peach Buds
Authors: Altree-Williams S , Howden MEH , Keegan JT , Malcolm HDR , Wyllie SG
Published: January 2006

Plant growth inhibitors identified in acidic extracts of flower buds from mature peach trees were p-coumaric acid, feruIic acid, an isomeric hydroxymethoxycinnamic acid, a dihydroxycinnamic acid having the properties of 3,5-dihydroxycinnamic acid, and benzoic acid. The inhibitors were isolated by preparative gas-liquid chromatography, tested for growth activity on the wheat coleoptile straight-growth bioassay, and identified by high-resolution mass spectrometry.
Effects of Water Deficit on Leaf Development in Tobacco
Authors: Clough BF , Milthorpe FL
Published: January 2006

Leaf initiation, leaf area, and the numbers and areas of palisade cells in developing leaves at five nodes were followed during a period in which tobacco plants were deprived of water. The rate of leaf initiation in well-watered plants was constant with time, but was rapidly reduced by a small water deficit and ceased at leaf water potentials of less than - 750 J kg-1. Cell expansion showed a similar response to water shortage, but cell division was much less sensitive, continuing although at a reduced rate even after leaf expansion had ceased. The expansion of a leaf on a well-watered plant could be described by a simple logistic relation with time from unfolding. The course of cell number and size during expansion could be accounted for by assuming that cells always divided at the same size, that the proportion of cells passing into a further cycle of division decreased as a negative logistic of time and that all cells expanded in the same manner, i.e, over 4 days at a rate which fell linearly with time.
Precipitation Reactions Between Components of Plant Tissue Extracts
Authors: Jermyn MA
Published: January 2006

Precipitation lines are observed on gel-diffusion plates between many pairs of seed extracts. Interactions involving Canavalia ensiformis depend upon concanavalin A, and a number of extracts from other plant seeds contain a precipitant that mimics that lectin. Methyl a-D-mannopyranoside is a general inhibitor of the precipitation phenomenon and some form of protein-carbohydrate binding seems to be involved in all precipitations, although the exact nature of the macromolecules taking part is obscure. For the leguminous seeds Phaseolus vulgauis, Vicia faba and Cajanus cajan, precipitation reactions occur between extracts of cotyledons and extracts of tissues of the parent plants, even of the testa of the seeds. The nature of these reactions appears to be the same as those of the interspecies ones. Both types of reaction may be examples of ways in which plant cells recognize self from non-self. The material in P. vulgaris that reacts with concanavalin A is a group of globulin-like glycoproteins (5 % carbohydrate), heterogeneous in both charge and molecular weight but similar in overall amino acid analysis.
Accumulation of 4-Aminobutyrate in Trifolium subterraneum Root Nodules: Effect of Rhizobium trifolii Strain on Aminotransferase Activity
Authors: Freney JR , Gibson AH
Published: January 2006

This paper reports a study of the metabolism of 4-aminobutyrate in root nodules of T. subterraneum, as it affects the differential accumulation of this amino acid in nodules formed by two strains of R. trifolii-NA30 (accumulating) and TA1 (non-accumulating).
Examination of glutamate decarboxylase activity in extracts of TA1 and NA30 nodules indicated that both systems could form 4-aminobutyrate with equal facility. On the other hand, similar preparations of TA1 nodules could transaminate 4-aminobutyrate to succinic semialdehyde up to seven times more rapidly than preparations from NA30 nodules.
Endogenous inhibitors were found in extracts of both TA1 and NA30 nodules but they did not appear to be the reason for the large difference in aminotransferase activity which remained after most of the inhibitors had been removed by dialysis. The difference in aminotransferase activity may be due to a difference in amounts of enzymes in TA1 and NA30 nodules but further work on the reactions of purified enzymes will be required to substantiate the suggestion.
The Photosynthetic Capacity of the Phytoplankton in the Waters of a Coral Reef
Authors: Griffiths DJ
Published: January 2006

Phytoplankton are relatively scarce in surface waters in a region of the Great Barrier Reef near Lizard Island. The phytoplankton sampled have a high rate of photosynthetic efficiency (1.2 millimoles CO2 fixed per milligram chlorophyll a per hour), although between 30 and 50% of the total carbon fixed may be excreted in soluble form. The rate of photosynthetic CO2 fixation into the particulate fraction is sensitive to varying levels of oxygen, suggesting the existence of a photorespiratory mechanism, a factor which might significantly influence the photosynthetic productivity of the algae in these tropical waters.
Phosphoglycollate Phosphatase in Marine Algae: Isolation and Characterization from Halimeda cylindracea
Authors: Randall DD
Published: January 2006

Phosphoglycollate phosphatase was partially purified (107-fold) from the marine alga H. cylindracea. The partially purified enzyme was almost completely specific for phosphoglycollate as substrate, and had the following properties: a specific activity of 2.73, an apparent Km for phosphoglycollate of 8 x 10-4M, a pH optimum of 7.5 - 8 and a divalent cation requirement. The presence of the enzyme is discussed in relation to photorespiration in this alga.
The Pectinesterase of the Pulp of the Banana Fruit.
Authors: Brady CJ
Published: January 2006

The pectinesterase (pectin pectyl-hydrolase, EC 3.1.1.11) of the pulp of the banana fruit is completely solubilized by buffers containing 0.5M sodium acetate, and the activity of the enzyme in the pulp remains constant during ripening. An apparent change in the ease of extraction as ripening progresses may be artefactual. The enzyme has been purified 200-fold from climacteric fruit. In either case, a molecular weight about 30 000 is indicated by chromatography through Sephadex G200. After isoelectric focusing, the enzyme was found in two peaks, at pH 8.8 - 8.9 and at pH 9.3 - 9.4. The enzyme in the two peaks is of the same molecular size, and shows only minor differences in responses to pH, salt and polyol concentration during assay. These results are discussed in relation to previous publications concerning changes in pectinesterase activity and properties during ripening of banana fruits.
Inflorescence Initiation in Lolium temulentum L. XIV. The Role of Phytochrome in Long Day Induction
Authors: Evans LT
Published: January 2006

Plants of L. temulentum grown in short days were exposed at various times during one night to mixtures of red (R) and far red (FR) light or to prolonged irradiation on a spectrograph.
Irradiation with red light through the latter half of the 16-h night was inductive of flowering, its effect being enhanced by exposure to FR during the first 6 h after the period in daylight. Brief exposure to FR during this initial period was as effective as continuous irradiation with FR, and its effect was reversible by brief subsequent exposure to R, implicating the pigment phytochrome.
Brief exposures to mixtures of R + FR at various times during the first 6 h in darkness were used to chart apparent changes in the two forms of phytochrome. To judge from the R + FR mixtures giving null responses, phytochrome reverted from the Pfr to the Pr form progressively over the first 5 h of darkness. There was no evidence of inverse reversion after an initial exposure to FR. Optimum flowering response required most of the phytochrome to be present in the Pfr form in the initial hours after daylight, followed by a rise in the proportion of the Pfr form to that set by R.
Reflecting this shift during the night in the optimum proportion of Pfr, the spectrograph experiments indicated peak effectiveness in the far red region of the spectrum for irradiation at the end of the period in daylight, and in the red region (~670 nm) for irradiation during the latter part of the night.
Flower induction in this long day plant is optimal when phytochrome is mostly in the Pr form early in the night, and in the Pfr form later, a sequence opposite to that required by short day plants such as Pharbitis nil and Chenopodium rubrum.
Leguminous Seed Glycoproteins That Interact With Concanavalin A
Authors: Gleeson PA , Jermyn MA
Published: January 2006

Material that interacts with concanavalin A has been purified from seed extracts of 18 species (16 legumes, Coffea arabica and Lolium perenne) by Con A-Sepharose chromatography. When examined by sodium dodecyl sulphate-polyacrylamide disc gel electrophoresis, many of the preparations showed a number of protein-staining components. All the preparations gave a single precipitation line against Cunalialia ensiformis crude extract on gel diffusion plates. Some of the con A-interacting preparations were shown to possess haemagglutination activity. The Arachis hypogaea (peanut) preparation contains one major glycoprotein of molecular weight 69 000, which was further purified and analysed. The purified glycoprotein contains 12% carbohydrate, galactose being the major sugar with minor amounts of mannose and xylose present.
Responses of Subterranean Clover Communities to Temperature. II. Effects of Temperature on Dark Respiration Rate
Authors: Fukai S , Silsbury JH
Published: January 2006

The rates of dark respiration of subterranean clover communities, grown at 12, 16, 20 and 24°C in naturally lit temperature-controlled glasshouses, were measured several times during growth. The dark respiration rate, measured at growth temperature, increased linearly with increase in plant dry matter for each temperature and it increased approximately linearly with increase in temperature at a given dry matter. A low crop growth rate shown by communities with dry matter greater than 300 g m-2 at a temperature of 24°C was largely accounted for by a high respiration rate. The temperature coefficient of dark respiration (Q10) was inversely related to growth temperature. Dark respiration rate at 28°C was lower for communities grown at 24°C than for communities grown at 12 or 16°C when the comparison was made at the same dry matter.
Calculated dark respiration rate from shoot dry matter, growth temperature and current measured temperature was close to the measured rate, indicating the dark respiration rate of subterranean clover communities to be largely accounted for by these factors. Use of an integrated form of a growth equation and allowing for dark efflux shows, on a 12 hour day, the rate of dry matter accumulation at 24°C to be the same as that at 12°C.
Interactions Between Chloride and Nitrate Uptake in Citrus Leaf Slices
Authors: Smith FA , Fox AL
Published: January 2006

Uptake of Cl into Citrus leaf slices is decreased by external NO3. With 0.5 mM external CI, the decrease is smaller than that produced by equivalent amounts of Br, but with 10 mM external Cl the effects of NO3 and Br are similar. Uptake of NO3 is decreased by external Cl.
When slices are pretreated in KCl, KNO3 or KHCO3, giving high intracellular K salt concentrations, uptake of Cl and NO3 again decreases. Effects of internal Cl and carboxylates can be distinguished, and uptake appears to be altered by internal ion levels in a manner analogous to that previously demonstrated with other plant tissues. The suggestion that leaf cells may lack some of the regulatory systems present in roots is discussed.
Individual Plant Variability in Susceptibility to Potassium Deficiency: Some Observations on Capeweed [Arctotheca calendula (L.) Levyns]
Authors: Asher CJ , Ozanne PG
Published: January 2006

Individual plants in an apparently uniform set of capeweed seedlings were found to differ markedly in susceptibility to potassium deficiency when grown in solution culture at a constant potassium concentration of 2.6 �M. Large differences were found in dry weight of tops (8-218 mg), tissue potassium concentration (0.3 - 4.8 %) and total potassium in the tops (23-10 500 �g potassium). Dry weight and percentage potassium were positively correlated
(r = 0.859, P<0.001) at 2.6 �M potassium but not at higher potassium concentrations. The nature and possible exploitation of such variability in cross-fertilized forage plants are briefly discussed.
Altitudinal Variation in the Photosynthetic Characteristics of Snow Gum, Eucalyptus pauciflora Sieb. ex Spreng. V. Rate of Acclimation to an Altered Growth Environment
Authors: Slayter RO , Ferrar PJ
Published: January 2006

Established, field-grown, seedlings of Eucalyptus pauciflora were transferred from high- and low- elevation field sites to a controlled-environment greenhouse in Canberra (maximum/minimum daily temperature range 26/15°) and the pattern of photosynthetic acclimation observed. Levels of net photosynthesis, Pamb, intracellular resistance rI, and leaf gas-phase resistance to CO2 transfer (r1) were monitored, as were the temperature optima for these parameters.
Acclimation proceeded most rapidly in the material grown at the warmer, low-elevation, site (955 m), and in the low-elevation population. Daily maximum/minimum temperatures at this site for the 10 days prior to transfer averaged 23/11°. With this material, levels of, and the temperature optimum for, Pamb reached control levels within 6 days of transfer from the field environment. By comparison, Pamb in the high-elevation population grown at the high-elevation (tree-line) site (1910 m) where the 10-day temperature averaged 15/7°, did not reach control levels until 14 days after transfer, and the temperature optimum for Pamb required 20 days to reach the control level. In general, the patterns of change in rI and r1 paralleled those in Pamb. Both the level of physiological activity in the field, and the temperature differences between the field and greenhouse environment, appeared to affect the rate of acclimation.
Immediately after transfer from the field, the temperature optima of the high-and low-elevation populations were close to the daily maximum temperature of the respective field environments. The temperature optimum of the high-elevation material grown at the low-elevation site was intermediate in value. At the conclusion of the acclimation period, the temperature optima of both high-elevation populations had converged to a value similar to that of the high-elevation control (about 22°); similarly, the temperature optimum of the low-elevation populations had reached the level of the low-elevation control (27°) These various temperature optima are interpreted on the basis that each population has a 'preferred' temperature which can be modified by different effective growth temperatures to yield different optima in different thermal environments. In the field, the effective temperature appears to be intermediate between the prevailing maximum and minimum temperatures.
Ultrastructural Features of Molybdenum Deficiency and Whiptail of Cauliflower Leaves: Effects of Nitrogen Source and Tungsten Substitution for Molybdenum
Authors: Fido RJ , Gundry CS , Hewitt EJ , Notton BA
Published: January 2006

Cauliflower plants were grown in sand culture with molybdenum-free nutrients: containing sodium nitrate, ammonium sulphate or ammonium nitrate as nitrogen sources and without, or with 0.1 or 0.25 ppm tungsten. Control plants were given 0.05 ppm molybdenum. After 6 weeks' growth primary visual lesions of the whiptail disorder appeared in molybdenum-deficient plants grown with ammonium sulphate. Samples of lamina from around these lesion areas, and from corresponding areas in chlorotic plants grown with nitrate or from control plants, were prepared for electron microscopy. In molybdenum-deficient plants grown with nitrate, chloroplasts became bulbous and enlarged but had reduced grana stacking and distorted expansion of intrathylakoid spaces. Decrease of electron density and appearance of cavities in the stroma were followed by spherical protrusions from the surface of the chloroplast bounded initially by both chloroplast and tonoplast membranes. These protrusions became filled with chloroplast debris or ruptured. In plants grown with ammonium, chloroplast structure appeared normal except in, or close to, lesion areas where their appearance resembled those grown with nitrate. In cells near the centre of lesions chloroplasts disintegrated into the cytoplasm. Mitochondria appeared to remain relatively undamaged. Addition of tungsten to the nutrient resulted in suppression of molybdenum-deficiency symptoms both visually and microscopically. Chloroplast integrity was preserved; cavities in the grana stacking were much less evident but areas of electron transparency persisted. The resemblance of the symptoms described to superoxide damage of lipid membranes is discussed with respect to the known biochemical changes which take place in ascorbic acid, S-methylcysteine sulphoxide and cytochrome c reductase levels as a result of molybdenum deficiency in cauliflowers.
Nitrogen, Phosphorus and Water Contents During Grain Development and Maturation in Wheat
Authors: Sofield I , Wardlaw IF , Evans LT , Zee SY
Published: January 2006

Plants of five cultivars of wheat were grown under controlled-environmental conditions in order to analyse the effect of cultivar and of temperature and illuminance after anthesis on the accumulation of nitrogen and phosphorus by grains in relation to dry matter. The water relations of the grain during maturation were also examined, using calcium content as an index of water entry.
The nitrogen and phosphorus contents of grains increased linearly throughout the grain growth period. The percentage of nitrogen and phosphorus in grains fell sharply during the first few days after anthesis but rose progressively thereafter. The higher the temperature, and the lower the illuminance, the higher was the percentage of nitrogen in the grain of all cultivars. Such conditions also reduce final grain size, but their effects on nitrogen concentration in the grain were apparent early in grain development. No evidence was found of a flush of nitrogen or phosphorus into the grain late in its development.
Water entry into the grain continued at a steady rate until maximum grain dry weight was reached, then ceased suddenly. No evidence was found of an increased rate of water loss by the grain at that stage, and the rapid fall in water content at the cessation of grain growth may have been due to blockage of the chalazal zone of entry into the grain by the deposition of lipids. Accumulation of dry matter, nitrogen and phosphorus and entry of water into the grain all ceased at the time of lipid deposition in the chalazal zone.
Globoids in Protein Bodies of Legume Seed Cotyledons
Authors: Lott JNA , Buttrose MS
Published: January 2006

Inclusions were found in protein bodies in cotyledons of seeds of each of five legume species (Acacia conferta, Cassia artemisioides, Clianthus formosus, Glycine max, Vicia faba). They were studied by a number of techniques: thin sectioning of fixed, embedded tissue; freeze-fracturing of unfixed tissue; chemical analysis of P, K, Mg and Ca content; and energy dispersive X-ray (EDX) analysis of both sections of glutaraldehyde-fixed tissue and freeze-dried tissue powders. The results of the studies presented in this paper, combined with a critical evaluation of the published research on legume protein body structure, lead us to believe that globoid crystals are a frequent occurrence in legume protein bodies. EDX analysis results indicate that electron-dense globoid crystals are rich in phytin and that phytin may also be present throughout the proteinaceous matrix portions of some legume protein bodies.
Manganese and Iron in Globoid Crystals of Protein Bodies From Avena and Casuarina
Authors: Buttrose MS
Published: January 2006

The storage protein bodies of plant seeds usually contain globoid crystals with a high content of phytin, a rich store of Mg, P, K and Ca. By energy dispersive X-ray analysis, Mn and Fe have now been located in the globoid crystals of protein bodies in the seed embryos of Avena sativa and Casuarina species. Their levels in sections of globoids, relative to the levels of the major elements present, is consistent with their relative levels stored in whole seeds of various species as determined by chemical analysis.