bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of pisciviory by resident predatory reef fish at One Tree Reef, Great Barrier Reef
Authors: Connell S. D.
Published: August 2004

Patterns of piscivory were investigated among five abundant species of
predatory fish at One Tree Reef, Great Barrier Reef, Australia. The guts of
two lutjanids Lutjanus carponotatus and
Lutjanus fulviflamma, two labrids
Cheilinus diagrammus and
Thalassoma lunare, and a serranid
Epinephelus quoyanus were examined for type, length,
number and volume of prey at two times of the day: sunrise and sunset. Each of
these species consumed fish, but only T. lunare and the
two lutjanids consumed recruit-sized fish. This information is important
because there is often scepticism as to whether large predators (>200 mm
TL) such as lutjanids consume new recruits. Only in the lutjanids were there
differences in the number and volume of prey present in the gut at sunrise and
at sunset; at sunset, few lutjanid specimens contained prey, whereas at
sunrise 98% of specimens contained prey. This result, in conjunction
with studies of nocturnal activity, suggest that patterns of predation
pressure inferred from daylight observations of predator abundance may have
little relevance to actual patterns of predation at local scales.
New Zealand shark fisheries: development, size and management
Authors: Francis Malcolm P.
Published: August 2004

New Zealand’s shark fisheries have increased steadily since 1975 to
reach 17 000–19 000 t per year. Commercial fisheries catch mainly spiny
dogfish (Squalus acanthias), school shark
(Galeorhinus galeus), skates
(Raja nasuta and R. innominata),
ghost sharks (Hydrolagus novaezealandiae and
Hydrolagus sp.), rig
(Mustelus lenticulatus) and elephantfish
(Callorhinchus milii). School shark, rig and
elephantfish fisheries have long histories, and catches are limited by
Individual Transferable Quotas. Fisheries for spiny dogfish, skates and ghost
sharks have only developed since 1979. Spiny dogfish and skate landings are
partially regulated by total quotas. Other sharks are prohibited target
species. Blue (Prionace glauca), porbeagle
(Lamna nasus) and mako
(Isurus oxyrinchus) sharks are taken as by-catch of the
tuna longline fishery. There is a small recreational catch of spiny dogfish,
school shark, rig, mako shark and blue shark. Historically important Maori
fisheries for spiny dogfish, school shark and rig are now minor. A beach
netting programme has operated off Dunedin beaches since 1969 to protect
swimmers from shark attacks. Fisheries management measures include commercial
quotas, prohibitions on target fishing many species, recreational bag limits,
limits on set-net length, mesh size and soak time, and closure of many inshore
waters to set-netting, trawling and Danish seining.
Factors associated with variations in abundance of epifaunal caridean shrimps between and within estuarine seagrass meadows
Authors: Walsh C. J. , Mitchell B. D.
Published: August 2004

The patterns of abundance of epifaunal caridean shrimps in seagrass meadows of
the Hopkins River estuary, south-western Victoria, Australia were described,
and environmental factors that best explained abundance patterns were sought
at two scales: within and between meadows. The abundances of the three
species, Macrobrachium intermedium,
Paratya australiensis and
Palaemon serenus, were strongly related to the position
of meadows within the estuary. Patterns of abundance between meadows were
likely to be determined by distribution of larval recruits, and extent of
post- larval migration, both between meadows and to and from stocks outside
the estuary (the river upstream for Paratya, and
adjacent coastal waters for Macrobrachium and
Palaemon). Variation in caridean abundances over 1 year
was related to temperature and salinity. Patterns of recruitment and migration
could in part be explained by physiological responses to physico-chemical
changes. However, it is hypothesized that competitive exclusion from preferred
deeper parts of meadows is a trigger for migration of
Paratya from the estuary. Although caridean densities
within some meadows were at times correlated with seagrass biomass, patterns
of seagrass abundance did not explain between-meadow patterns of caridean
abundance well.
Rationales and practices of mangrove afforestation
Authors: Field Colin
Published: August 2004

The goals of mangrove afforestation for the purposes of conservation and
landscaping, sustainable yield of natural products and the protection of
coastlines are identified. Basic practical considerations for the planting of
mangroves such as site selection, species selection, planting and monitoring
are presented. Finally, there is a brief discussion of the research needs in
this area.
Changes in benthic communities of Port Phillip Bay, Australia, between 1969 and 1995
Authors: Wilson Robin S. , Heislers Simon , Poore Gary C. B.
Published: August 2004

Changes in benthic communities in Port Phillip Bay, Australia, were assessed
over a 25- year period by comparing an intense bay-wide survey carried out in
the early 1970s, a 3-year study in the mid 1970s, a limited survey in the
early 1990s, and a resurvey in the mid 1990s. A major division of benthic
communities into those on deeper muddy sediments and those on marginal sandy
sediments persisted was less well defined (by ordination methods) in the 1990s
than in the 1970s. The densities of individuals and species declined
significantly, but absolute numbers of taxa did not change noticeably.
Nevertheless, temporal variability in all variables over 25 years was within
the range reported for the 3- year study. Polychaetes have become relatively
more abundant than crustaceans and molluscs, and the proportion of
suspension-feeding organisms has increased at the expense of deposit feeders.
The introduced Japanese bivalve Theora lubrica was the
most abundant invertebrate in the 1970s. In the 1990s, this species, the
European bivalve Corbula gibba and the polychaete
Euchone limnicola were the most abundant. Decreasing
abundances of macrobenthic invertebrates, and a decreasing proportion of
deposit feeders, is consistent with a decrease in nutrient load from moderate
to low levels—such as occurred with reduced discharge from
Melbourne’s sewage treatment plant—but lack of contemporaneous
data prevents further explanation.
Heavy metal pollution and macrobenthic assemblages in soft sediments in two Sydney estuaries, Australia
Authors: Stark Jonathan S.
Published: August 2004

The influence of heavy metals (copper, lead and zinc) associated with urban
runoff, on assemblages of macrofauna in intertidal soft sediments was studied
in two estuaries in the Sydney region. The patterns of distribution and
abundance of fauna and assemblages was found to vary significantly at several
spatial scales: within bays in an estuary, between bays within an estuary and
between bays from different estuaries. Significant differences were found in
concentrations of heavy metals in sediments, but there was very little
difference among bays in other environmental variables: grain-size
characteristics and organic matter content of sediments. Bays polluted by
heavy metals had significantly different assemblages to unpolluted bays, were
generally less diverse and were characterized by an order-of-magnitude greater
abundance of capitellids, spionids, nereids and bivalves. Unpolluted bays had
greater abundance of crustaceans and several polychaete families, including
paraonids and nephtyids and were generally more diverse. There was a
significant correlation between patterns of assemblages and concentrations of
heavy metals, but not with other environmental variables.
Incidental catch associated with swordfish longline fisheries in the south-west Atlantic Ocean
Authors: Marín Yamandú H. , Brum Federico , Barea Luis C. , Chocca Julio F.
Published: August 2004

This paper describes the composition of the harvest by species of two vessels
operating with two different pelagic longline systems aimed at swordfish
(Xiphias gladius). Four zones were surveyed in the
Uruguayan EEZ and international waters in the south-western Atlantic. Data
were collected by observers on board who recorded the number of individuals in
each of the species caught. In all, 50 species were caught, of which 15 were
cartilaginous fish, 27 were teleosts and eight were ‘non- fish’
species (birds, mammals and turtles). The most abundant species were blue
shark (Prionace glauca) (43%), swordfish
(27%) and albacore tuna (Thunnus alalunga)
(9%). The abundances of blue shark and of swordfish differed
significantly between the two rigging systems and among the four zones. The
catch was classified into three marketing groups: primary marketing (swordfish
and high-price tuna), secondary marketing (non-target species but marketable)
and discards (with no commercial value). In terms of numbers, the first two
groups represented between 91% and 72% of the species collected.
This percentage may vary if the catch is analysed by weight, as only part of
the carcass and shark fins are used.
Resumen. Se describe la composición por especies
de la captura de dos buques que operaron con dos sistemas diferentes de
palangre pelágico dirijido a la extracción de pez espada
(Xiphias gladius). Se relevaron quatros áreas que
abarcaron la ZEE uruguaya y aguas internacionales en el O. Atlántico.
Los datos fueron colectados a bordo por observadores, registrando la captura
en número de la totalidad de las especies. Se contabilizó un
total de 50 especies capturadas, de las cuales 15 corresponden a peces
cartilaginosos, 27 a peces óseos y 8 a ‘non-pisces’ (aves,
mamíferos y quelonios). Las especies más representadas fueron el
tiburón azul (Prionace glauca) (43%),
seguida por pez espada (27%) y albacora
(Thunnus alalunga) (9,0%). La presencia de
tiburón azul y pez espada mostró diferencias significativas
comparando los dos sistemas de construcción del palangre y las zonas.
Se clasificó la captura en tres grupos de comercialización:
comercialización primaria (pez espada y atunes de elevado valor),
comercialización secundaria (especies diferentes de la objetivo pero
comercializables), y decarte (sin valor comercial). Las dos primeras
acumularon entre el 91% y 72% de las piezas capturadas. Este
porcentaje puede variar si se analiza la captura en peso, ya que de los
tiburones se aprovechan las aletas y solamente parte de las carcasas.
Size structure of river zooplankton: seasonal variation, overall pattern and functional aspect
Authors: Kobayashi Tsuyoshi , Shiel Russell J. , Gibbs Philip
Published: August 2004

Density–size distributions of a river zooplankton community were
examined about biweekly over a year in the upper tidal freshwater portion of a
regulated Australian river, specifically the Hawkesbury–Nepean. Results
were compared with those of similar studies in lakes (and reservoirs) to
characterize the similarities and differences in the structure and grazing
function of river and lake zooplankton communities. The density–size
distributions of the river zooplankton community were similar to those of lake
plankton communities, in terms of a marked temporal variation in shape and
overall bimodal shape. They differed in terms of the truncation of the upper
body size and the absence of a significant relationship between the slope
(regression coefficient) of a log-linear density–size model and
environmental variables. The river zooplankton community appeared to have a
high average rate of biomass increase when measured against body-mass class
and a low mass-specific grazing rate, compared with those of lake communities.
Because of methodological differences between studies, inter-system
comparisons of size spectra and grazing rates need cautious interpretations
and generalizations.
Stomatal conductance and gas exchange in four species of Caribbean mangroves exposed to ambient and increased CO2
Authors: Snedaker Samuel C. , Araújo Rafael J.
Published: August 2004

Stomatal conductance and gas exchange rates in sun leaves were measured in
multiple individuals of four species of Caribbean mangroves common to south
Florida, USA. Under ambient CO2 levels (340–360
ppm), stomatal conductance (mol m-2
s-1), net primary productivity (g
CO2 m-2
min-1), transpiration (g H2O
m-2 s-1), and instantaneous
transpiration efficiency, ITE, (µmol CO2/mmol
H2O) were not significantly different among the four
species: Rhizophora mangle (Rm),
Avicennia germinans (Ag),
Laguncularia racemosa (Lr), and
Conocarpus erectus (Ce). Under exposure to increased
CO2 (361–485 ppm) there were highly significant
(P < 0.001) decreases in stomatal conductance and
transpiration, and a highly significant increase in ITE in all four species.
However, there was no significant change in net primary productivity in Rm, Ag
and Ce, whereas there was a significant decrease (P <
0.01) in net primary productivity in Lr.
PCR-based genetic identification of marlin and other billfish
Authors: Innes B. H. , Grewe P. M. , Ward R. D.
Published: August 2004

A genetic test was developed for the identification of the six species of
billfish found in Australian waters (black marlin, Indo–Pacific blue
marlin, striped marlin, Indo–Pacific sailfish, shortbill spearfish and
broadbill swordfish). The test was based on the PCR–RFLP analysis of a
1400 bp region of the mitochondrial DNA molecule, the d-loop, using four
restriction enzymes (Hinf I, Rsa I
and Sau3A I andTaq I). A total of
33 composite haplotypes were observed among 160 fish; all were
species-specific. Three of the species—black marlin, striped marlin and
broadbill swordfish—showed sufficient intra-specific variation to be
useful in population structure analyses.
Correlation between carbon isotope discrimination and transpiration efficiency in lines of the C4 species Sorghum bicolor in the glasshouse and the field
Authors: Henderson S. , Caemmerer S. von , Farquhar G.D. , Wade L. , Hammer G.
Published: August 2004

Transpiration efficiency, W, the ratio of plant carbon
produced to water transpired and carbon isotope discrimination of leaf dry
matter, Δd, were measured together on 30 lines of
the C4 species, Sorghum bicolor,
in the glasshouse and on eight lines grown in the field. In the glasshouse,
the mean W observed was 4.9 mmol C
mol-1 H2O and the range was 0.8
mmol C mol -1 H2O. The mean
Δd was 3.0 and the observed range was 0.4‰.
In the field, the mean W was lower at 2.8 mmol C
mol-1 H2O and the mean
Δd was 4.6‰. Significant positive
correlations between W and
Δd were observed for plants grown in the
glasshouse and in the field. The observed correlations were consistent with
theory, opposite to those for C3 species, and showed
that variation in Δd was an integrated measure of
long-term variation in the ratio of intercellular to ambient
CO2 partial pressure,
pi/pa.
Detailed gas exchange measurements of carbon isotope discrimination during
CO2 uptake, ΔA, and
pi/pa
were made on leaves of eight S. bicolorlines. The
observed relationship between ΔA and
pi/pa
was linear with a negative slope of 3.7‰ in
ΔA for a unit change in
pi/pa.
The slope of this linear relationship between ΔA
and
pi/pa
in C4 species is dependent on the leakiness of the
CO2 concentrating mechanism of the
C4 pathway. We estimated the leakiness (defined as the
fraction of CO2 released in the bundle sheath by
C4 acid decarboxylations, which is lost by leakage) to
be 0.2. We conclude that, although variation in Δd
observed in the 30 lines of S. bicolor is smaller than
that commonly observed in C3 species, it also reflects
variation in transpiration efficiency, W. Among the
eight lines examined in detail and in the environments used, there was
considerable genotype × environment interaction.
Laser-induced Chlorophyll Fluorescence Ratio in Certain Plants Exhibiting Leaf Heliotropism
Authors: Sailaja M. V. , Chandrasekhar Y. , Rao D. Narayana , Das V. S. Rama
Published: August 2004

Laser-induced
F685/F720
chlorophyll fluorescence of intact leaves in solar tracking plants from
Euphorbiaceae (Ricinus communis L.), Amaranthaceae
(Amaranthus gangeticus L.,
Amaranthus viridis L.), Malvaceae
(Hibiscus cannabinus L.,
Althaea rosea L.), Fabaceae
(Dolichos lablab L.) Capparadaceae
(Cleome gynandra L.) exhibited remarkable diurnal
constancy in contrast to those of compass plants from Poaceae
(Oryza sativa L.) and Amaranthaceae
(Telanthera ficoides Moq.) with fixed leaf orientation.
The
F685/F720
ratio remained constant in both the diaheliotropic and paraheliotropic plants,
but it decreased during midday in compass plants. The acquired spectra were
analysed in terms of Gaussian parameters to determine the relative intensity
of contribution of various bands; the data suggested a decrease in both the
F685 and the
F720 bands at 1230 h in compass
plants while they remained unaltered in reorienting leaves. The typical midday
depression in
F685/F720
ratio observed in compass plants may be due to down-regulation of both
photosystems, I and II. This unique behaviour of diurnal constancy in
laser-induced
F685/F720
suggests that the leaves of diaheliotropic plants maximise light-use
efficiency throughout the day and avoid the hazard of midday depression of
photosynthesis.
Seed-specific expression of the isopentenyl transferase gene (ipt) in transgenic tobacco
Authors: Ma Qing-Hu , Zhang Ren , Hocart Charles H. , Letham David S. , Higgins Thomas J. V.
Published: August 2004

The Agrobacterium tumefaciens gene encoding isopentenyl
transferase (ipt), a cytokinin biosynthetic gene, was
fused to a promoter from a seed-specific gene, vicilin, and introduced into
tobacco cells. Intact fertile plants were generated. The expression of the
vicilin-ipt gene was shown to be confined to seed and
resulted in enhanced levels of cytokinins in the developing seeds and
increased seed protein content. Using a simplified quantification method, a
significant increase in the levels of endogenous cytokinins was recorded at
16–21 days after flowering. The growth of the transgenic plants and the
development of the seeds appeared to be normal.
Light-dependent Activation of NADP-Malate Dehydrogenase: a Complex Process
Authors: Miginiac-Maslow Myroslawa , Issakidis Emmanuelle , Lemaire Martine , Ruelland Eric , Jacquot Jean-Pierre , Decottignies Paulette
Published: August 2004

After the discovery of the light-activation properties of the chloroplastic
NADP-dependent malate dehydrogenase in 1970, the elements of the activation
pathway were identified and shown to consist of the stromal proteins of the
ferredoxin/thioredoxin system. It was further demonstrated that the
activation was a reductive process during which disulfides were reduced into
dithiols by reduced thioredoxin. Sequence alignments with the permanently
active NAD-malate dehydrogenases revealed N- and
C-terminal extensions specific for the light-regulated
form. A regulatory disulfide was identified in the amino-terminal extension by
chemical derivatisation: its reduction was correlated to the activation of the
enzyme. The use of site-directed mutagenesis techniques revealed the
complexity of the intramolecular activation mechanism, showing that two
different disulfides were reduced per subunit of this homodimeric enzyme: one
located in the N-terminal extension, the other in the
C-terminal extension. A model was proposed where the
C-terminal extension locks the access to the active
site, whereas the N-terminal extension governs the
conformation of the active site. The identification of the catalytic histidine
allowed us to test the accessibility of the active site and to demonstrate the
validity of the proposed model.
Spatial Patterns of Carbon Isotope Discrimination and Allocation of Photosynthetic Activity in Sugarcane Leaves
Authors: Meinzer Frederick C. , Saliendra Nicanor Z.
Published: August 2004

Longitudinal variation in carbon isotope discrimination (Δ),
photosynthetic gas exchange, phosphoenolpyruvate
carboxylase (PEPC) and ribulose 1,5-bisphosphate carboxylase/oxygenase
(Rubisco) activities, chlorophyll and N content were characterised in the
uppermost fully expanded leaf of sugarcane (Saccharum
spp. hybrid) plants. Δ values of lamina tissue and the water-soluble
fraction increased from the base to near the tip of the leaf then remained
essentially constant, or declined along the rest of the leaf. Both the
CO2 assimilation rate (A) and
stomatal conductance (g) also increased from the base to
the tip. The relative increase in A was much greater
than that of g, causing the ratio of intercellular to
ambient partial pressure of CO2
(pi/pa)
to decrease substantially from leaf base to tip. Activities of both PEPC and
Rubisco increased from leaf base to tip. Based on current models of factors
determining Δ in C4 plants, the increase in
Δ from the base to tip of sugarcane leaves appeared to be entirely
attributable to decreasing
pi/pa.
Bundle sheath leakiness to CO2, the other major
determinant of Δ in C4 plants, was nearly constant
from the leaf base to tip, consistent with the nearly constant ratio of
Rubisco and PEPC activity. Spatial allocations of carboxylase activity,
chlorophyll, and N were highly correlated with prevailing levels of incident
light at different points along the leaf. Partitioning of N and photosynthetic
activity within individual leaves was consistent with allocation of N and
photosynthetic capacity along vertical gradients of incident light reported
for entire canopies.
Effect of soil type on nitrogen balance at maturity in wheat characterized using 15N-labelled NH4 NO3-fertilizer and sink - source modifications at flowering
Authors: Hannachi Lynda , Bousser Agnès , Deléens Eliane
Published: August 2004

Wheat plants were grown in a greenhouse in containers filled with chalky or
loamy soil. Single-labelled ammonium nitrate fertilizer
NH415NO3 or
15NH4 NO3 (5
atom% 15N) was applied in a split-dose after the
third leaf-stage. Initial soil nitrate levels were lower in chalky soil. At
maturity, the amount of N recovered in shoots was lower in chalky plants (CP)
than in loamy plants (LP) but N fertilizer recovery was higher in CP than in
LP. There was a greater 15NO3
recovery, in CP: 15NO3 /
15NH4 being 1 in LP and 1.3 in CP
seeds. This was explained by efficient N mobilization enriched in
15NO3 in CP. Leaf excision or
shoot shading at flowering changed the seed
15NO3 /
15NH4 ratio; it increased in CP
and decreased in LP for plants with excised leaves whereas it was not modified
in CP but decreased in LP for shaded plants. This indicated that grain filling
was predominantly via mobilization in CP, whereas a late
assimilation was involved in LP. The flag leaf in CP was the site for early
and transient storage of NO3- and
later a main source of assimilated N for seeds. Benefits previously observed
in vegetative wheat plants grown on chalky soils compared to loamy soils with
respect to enhanced NO3 utilisation, are also manifest
at grain-filling and maturity.
Visualisation of Freezing Behaviours in Flower Bud Tissues of Cold-hardy Rhododendron japonicum by Nuclear Magnetic Resonance Micro-Imaging
Authors: Price William S. , Ide Hiroyuki , Arata Yoji , Ishikawa Masaya
Published: August 2004

1H nuclear magnetic resonance (NMR) micro-imaging was
used to study the freezing behaviour of wintering flower buds of
Rhododendron japonicum (A. Gray) Suringer. Amulti-slice
multi- echo pulse sequence was used to acquire images at different subfreezing
temperatures. The images obtained predominantly reflected the density of
mobile (i.e. non-ice) protons mainly from unfrozen water. By comparing these
images taken at various subfreezing temperatures, we could determine which
tissues produced high temperature exotherms and low temperature exotherms in
differential thermal analyses. In flower buds of the cold-hardy
R. japonicum, typical extra-organ freezing was
successfully imaged. The scales readily froze at –7°C but some
florets remained supercooled even at –21°C. The size of the
supercooled florets was reduced with decreasing temperature which indicated a
gradual decrease in floret water content. With decreasing temperature, there
was a gradual decrease in the signal intensity of the flower bud axis
including the peduncle and immature pith tissues, which implies either
dehydration or partial freezing of these tissues. Deep supercooling in the
entire mature pith tissues was also clearly visible in these images. Due to
its non-invasive nature, NMR micro-imaging is a useful tool for studying
freezing behaviours in various plant tissues, especially for imaging organised
or harmonised freezing in complex organs as well as for clarifying the
diversity and mechanisms involved in freezing behaviours.
An Antimicrobial Peptide from the Australian Native Hardenbergia violacea Provides the First Functionally Characterised Member of a Subfamily of Plant Defensins
Authors: Harrison Stuart J. , Marcus John P. , Goulter Kenneth C. , Green Jodie L. , Maclean Donald J. , Manners John M.
Published: August 2004

An antimicrobial peptide (HvAMP1) was isolated from
seeds of the Australian native legume
Hardenbergia violacea (Schneev.) Stearn. The peptide is
47 amino acid residues in length, contains 8 cysteines, and has a molecular
weight of 5392 and a predicted pI of 10.41. HvAMP1
inhibited the growth of several plant pathogenic fungi at concentrations as
low as 1 µM in vitro and produced distinct hyphal
distortion and increased branching. This antimicrobial activity was greatly
diminished in the presence of 1 mM CaCl2 and 50 mM KCl.
The purified peptide at 40 µM did not inhibit three different a-amylase
enzymes. Aeukaryotic cell-free translation system showed inhibition
approaching 50% in the presence of ~100 µM of
HvAMP1. The viability of plant and mammalian cells
cultured in vitro was not adversely affected by
concentrations of HvAMP1 as high as 40 mM. The amino
acid sequence of HvAMP1 contained the consensus amino
acids that define the plant defensin family of peptides. The
HvAMP1 amino acid sequence showed 87% and
57% identity with the amino acid sequences deduced from cDNA sequences
from defensins of Vigna unguiculata and
Pisum sativum, respectively. Other plant defensin
sequences showed less than 33% amino acid identity to the peptide.
Therefore, HvAMP1 and the putative plant defensins of
cowpea and pea define a distinct sequence subfamily of plant defensins which
is at present limited to members of the Fabaceae. HvAMP1
is the first member of this subfamily to be purified and functionally
characterised. The antimicrobial activity of HvAMP1
suggests a defensive role for this subfamily of peptides.
Absorption, translocation and metabolism of pyridate in chickpea (Cicer arietinum)
Authors: Giménez-Espinosa R. , Prado R. De
Published: August 2004

This work studied the tolerance mechanisms of chickpea
(Cicer arietinum L.) to pyridate, a post-emergence
herbicide used in other crops such as maize, peanut and wheat. Foliar
absorption of pyridate in chickpea was limited and occurred mainly during the
first 24 h after treatment. Over 83% of the herbicide absorbed remained
in the treated leaf 72 h after treatment. Twelve hours after herbicide
treatment, 50% of the total herbicide applied was converted to
CL9673-N-Gly, an intermediate metabolite essential in
the activation of the pyridazine ring for following conjugations. The
N-glycoside was conjugated to form more-polar
metabolites, C1 and C2: C1 was identified as
CL9673-N-Gly- glutathione; and C2 was identified as
CL9673-N-Gly-cysteine. C1 appeared 3 h after treatment
and reached a maximum of around 40% of recovered radioactivity 72 h
later, while C2 appeared 24 h after treatment and reached a maximum of
10% 72 h later. Chickpea glutathione transferases do not seem to be
involved in the formation of C1, thus the final amount of this conjugate
mainly depends on the amount of N-glycoside formation
in vivo.
Comparison of three selectable marker genes for transformation of wheat by microprojectile bombardment
Authors: Witrzens Barbara , Brettell Richard I.S. , Murray Fiona R. , McElroy David , Li Zhongyi , Dennis Elizabeth S.
Published: August 2004

Three selectable marker genes were compared for their efficacy in the
production of transgenic wheat plants following microprojectile bombardment of
cultured immature embryos. While transformed plants were recovered using the
bar (phosphinothricin acetyltransferase) gene in
combination with bialaphos, and the aphA (neomycin
phosphotransferase) gene in combination with geneticin or paromomycin, no
transgenic material was obtained with the hpt
(hygromycin phosphotransferase) gene and hygromycin B. Southern analysis
revealed single copy as well as multiple copy insertions of the
bar and aphA transgenes.
Inheritance of these selectable marker genes was demonstrated in the
T1 generation progenies.
Sequence and expression of a stem-abundant caffeic acid O-methyltransferase cDNA from perennial ryegrass (Lolium perenne)
Authors: McAlister Fiona M. , Jenkins Colin L. D. , Watson John M.
Published: August 2004

A perennial ryegrass (Lolium perenne) cDNA library was
screened with a PCR-amplified comt DNA fragment
generated from ryegrass cDNA template using degenerate oligonucleotide
primers. A full-length cDNA (LpeComt1) was isolated and
shown to encode a caffeic acid O-methyltransferase
(COMT) enzyme by analysis of its predicted amino acid sequence. This cDNA was
expressed in E.coli and COMT activity was demonstrated
in bacterial extracts. The predicted amino acid sequence of the perennial
ryegrass COMT was highly similar (88%) with that of a COMT isolated
from maize. Southern blot hybridisation analysis using this cDNA indicated
that it is a member of a small gene family comprising at least two genes in
perennial ryegrass. The LpeComt1 gene is strongly
expressed in stem tissue, but not obviously in shoot, leaf blade, leaf sheath,
flower or root tissue.
Fluxes of carbon and water in a Pinus radiata forest subject to soil water deficit
Authors: Arneth A. , Kelliher F.M. , McSeveny T.M. , Byers J.N.
Published: August 2004

We measured, by eddy covariance, seasonal CO2
(FCO2) and water
(E) fluxes in an 8-year-old New Zealand
Pinus radiata D.Don plantation subject to growing season
soil water deficit. Average rates of
FCO2 and E
were highest in spring (324 mmol m-2
d-1 and 207 mol m-2
d-1, respectively) when the abiotic environment was most
favourable for surface conductance and photosynthesis. During summer, fluxes
were impeded by soil water (θ) deficit and were equal to or smaller than
during winter (FCO2 = 46
mmol m-2 d-1 in summer and 115
mmol m-2 d-1 in winter;
E = 57 and 47 mol m-2
d-1, respectively). On particularly hot and dry days,
respiration exceeded photosynthetic uptake and the ecosystem was a net carbon
source.
Portraying the underlying biochemistry of photosynthesis, daytime half-hourly
FCO2 increased with quantum
irradiance absorbed by the canopy
(Qabs) following a non-saturating,
rectangular hyperbola. Except for winter, this relation was variable,
including hysteresis attributable to diurnal variation in air saturation
deficit (D). Daily ecosystem
FCO2,
FCO2/Qabs
and FCO2/E were inversely
proportional to maximum daily D, but in the cases of
FCO2 and
FCO2/Qabs
only after soil moisture deficit became established. Consequently, as the tree
growing season progressed, ecosystem carbon sequestration was strongly limited
by the co-occurrence of high D at low θ.
Partitioning of photosynthetic carbohydrates in leaves of salt-stressed olive plants
Authors: Gucci Riccardo , Moing Annick , Gravano Elisabetta , Gaudillère Jean Pierre
Published: August 2004

Changes in photosynthetic carbon partitioning were determined, during
14CO2 pulse-chase experiments, in
fully-expanded leaves of olive (Olea europaea L. cv.
Frantoio) plants treated in containers with 100 mM NaCl for 5 weeks and
compared with partitioning in leaves of untreated plants. Salt stress caused
an increase in the radioactivity partitioned into mannitol and a decrease of
that recovered as glucose. The radioactivity in sucrose was significantly
reduced in salt-treated plants after 19.5 min of chase. There was no
difference between the two treatments in the radioactivity found in fructose
and galactose, whereas a significant decrease in the radioactivity found in
stachyose and raffinose of salt-treated leaves was observed after 19.5 min
chase. The radioactivity incorporated into starch was 11 and 16% of the
total in control and salt-treated leaves respectively. There were no
significant differences in the leaf pools of soluble carbohydrates over the
chase period, except for mannitol which increased in the leaf tissue of
salt-treated plants. Over the course of the diurnal period, and under high
irradiance conditions, the leaf mannitol content increased more markedly in
salt-treated plants than in the controls. In contrast, contents of other
nonstructural carbohydrates were not affected by the 100 mM NaCl treatment.
Endogenous biosynthetic precursors of (+)-abscisic acid. VI. Carotenoids and ABA are formed by the ‘non-mevalonate’ triose-pyruvate pathway in chloroplasts
Authors: Milborrow B.V. , Lee H.-S.
Published: August 2004

A cell-free system from avocado fruit which routinely incorporated
[14C]mevalonate into ABA (1000 dpm per 5 mL of
preparation), and into carotenoids, has now been shown to incorporate
[14C]pyruvate even more successfully (1620
dpm). Intact chloroplasts from spinach leaf protoplasts incorporated 2990 dpm
of [14C]pyruvate (from 2 x
106 dpm) into ABA compared with 990 dpm from
[3-R-5-14C]mevalonate
(also from 2 x 106 dpm). The intact chloroplasts also
produced [14C]ABA (1575 dpm) when supplied
with [14C]isopentenyl diphosphate. This result
establishes that the whole pathway of biosynthesis of ABA can occur within
chloroplasts. Little [14C]acetate or
[14C]alanine was incorporated into ABA by
avocado fruit mesocarp. Most of the ABA in leaf tissue now appears to be
formed by the triose-pyruvate pathway in chloroplasts and incorporation of
[14C]mevalonate occurs after activation in the
cytoplasm and importation of a later intermediate into the plastids.
Abscisic acid induction of GTP hydrolysis in maize coleoptile plasma membranes
Authors: Irving Helen R.
Published: August 2004

Since receptor-coupled G proteins increase GTP hydrolysis (GTPase) activity
upon ligands binding to the receptor, a study was undertaken to determine if
abscisic acid (ABA) induced such an effect. Plasma membranes isolated from
etiolated maize (Zea mays L.) coleoptiles were enriched
in GTPase activity relative to microsomal fractions. Vanadate was included in
the assay to inhibit the high levels of vanadate sensitive low affinity
GTPases present. Under these conditions, GTPase activity was enhanced by
Mg2+, stimulated by mastoparan, and inhibited by
GTPγS indicating the presence of either monomeric or heterotrimeric G
proteins. The combination of NaF and AlCl3 is expected
to inhibit heterotrimeric G protein activity but had little effect on GTPase
activity in maize coleoptile membranes. Cholera toxin enhanced basal GTPase
activity, confirming the presence of heterotrimeric G proteins in maize plasma
membranes. Pertussis toxin also slightly enhanced basal GTPase activity in
maize membranes. Abscisic acid enhanced GTPase activity optimally at 5
mmol/L Mg2+ in a concentration dependent manner by
1.5-fold at 10 µmol/L and up to three-fold at 100 µmol/L
ABA. Abscisic acid induced GTPase activity was inhibited by GTPγS, the
combination of NaF and AlCl3, and pertussis toxin.
Overall, these results are typical of a receptor-coupled G protein responding
to its ligand.
Relationships between ash content, carbon isotope discrimination and yield in durum wheat
Authors: Araus J.L. , Amaro T. , Casadesús J. , Asbati A. , Nachit M.M.
Published: August 2004

The relationships between ash content, carbon isotope discrimination and yield
were studied in durum wheat (Triticum durum Desf.) grown
in a Mediterranean region (north-western Syria) under three different water
regimes (hereafter referred to as environments). Ash content (on dry mass
basis) was measured in the flag leaf about 3 weeks after anthesis (leaf ash)
and in mature kernels (kernel ash), whereas Δ was analysed in the
penultimate leaf at heading (leaf Δ) and in mature kernels (kernel
Δ). Leaf Δ was weakly or not related with the other parameters.
Leaf ash correlated positively with kernel Δ
(P≤0.001), even in the driest environment, which gave
a mean yield of 1.5 t ha-1. For the four parameters,
correlations with yield remained significant
(P≤0.001) after correcting for days to heading. All
the parameters showed a higher broad-sense heritability than yield. The
parameter that showed the best genetic correlation with grain yield was kernel
ash (r2= 0.88), followed by
kernel Δ (r2 = 0.69)
and leaf ash (r2 = 0.64),
whereas leaf Δ (r2 =
0.26) was the least correlated parameter. Except for kernel ash, these
parameters always correlated positively with grain yield. The negative
relationships of kernel ash (on dry mass basis) with yield and all the other
parameters may be attributable to the finding that kernel ash was higher in
those genotypes more affected by drought during grain filling. Thus, kernel
ash was negatively related (P≤0.001) with total
kernel mass per spike. Prediction of grain yield through multiple linear
regression suggests that kernel ash can be used as complementary criterion to
either kernel Δ or leaf ash.
Light regulation of anthocyanin, flavonoid and phenolic acid biosynthesis in potato minitubers in vitro
Authors: Lewis Christine E. , Walker John R.L. , Lancaster Jane E. , Conner Anthony J.
Published: August 2004

Unlike most flowers and fruit, some potato
(Solanum tuberosum L.) cultivars can produce
anthocyanin-pigmented tubers without direct exposure to light. This study used
minitubers developing on in vitro cultured potato plants
to study the effect of light on the regulation of anthocyanin and flavonoid
biosynthesis in tubers.
Although some potato cultivars produced anthocyanin in the dark, light
enhanced the production of anthocyanins, other flavonoids and phenolic acids
in all cultivars studied. After a minimum of 8 h exposure to light, minitubers
of Desirée showed a significant increase of anthocyanin which reached a
maximum after 10 d; other flavonoids and phenolic acids showed parallel
increases. The activities of enzymes in these pathways correlated with the
accumulation of these phenolics.
Illumination of the leaves initiated anthocyanin and flavonoid production in
foil-covered Desirée minitubers but at a slower rate compared to that
for light-exposed minitubers. Anthocyanin was produced first at the stem end
of the minituber and only later at the bud end. Thus, it appears that a
‘trigger’ compound was produced in the leaves as a result of
exposure to light, and this was transported to the tubers. Reciprocal grafting
experiments between potato cultivars with differently pigmented tubers showed
that the rootstock determined the potential for anthocyanin biosynthesis.
A comparison of soil survey methods in relation to catchment hydrology
Authors: Cook S. E. , Coles N. A.
Published: August 2004

Eight primary catchments within the Western Australian wheatbelt were surveyed
in detail to examine the abilities of conventional soil classification and
geostatistical analysis to provide detailed information of soil spatial
variation for catchment-scale hydrologic modelling. Nine soil physical
properties were measured. The results illustrate potential diculties with both
methods. Classification by using the Factual Key was unable to describe the
major component of soil property variation. The relative variance accounted
for by soil classes was usually <10%. Only the yellow duplex soils
appeared distinct from other soil classes. Potential diculties with
geostatistical analysis also arose because of fluctuations in the variogram
models. Contrasts occurred between variograms for the same property over
different catchments and for different properties over the same catchment.
Within the areas studied, nugget and linear (unbounded) variogram models were
more common than spherical or exponential models. It is proposed that the
surveyor would have to select a survey method on the basis of prior knowledge
about which model of variation is more likely to be successful for the scale
and location of survey.
Sorption of heavy metals by mineral-humic acid substrates
Authors: Spark K. M. , Wells J. D. , Johnson B. B.
Published: August 2004

The effect of humic acid on the sorption of metals by minerals was studied inrelation to the separate interactions of the humic acid with the minerals, thehumic acid with the metals, and the metals with the minerals. Sorption of themetals in combined mineral–humic acid systems can be explained in termsof generalised sorption reactions.Sorption of the metals in mineral–humic acid systems is dependent onsorption of humic acid by the mineral and on the solubility of themetal–humic acid complex. Sorption is enhanced in the combined systemsfor the minerals goethite and silica due to secondary reactions in whichmetal–humic acid complexes are adsorbed by the minerals. Sorption of themetal–humic acid complex in the combined systems for α-alumina and kaolinite is not enhanced, possibly due to competing reactions associated withthe sorption of the humic acid by these minerals.
Evaluating the potential of inorganic and organic ligands to extract aluminium from an acidic soil using batch and leaching cells
Authors: Smith C. J. , Gibson J. A. E. , Bond W. J.
Published: August 2004

Batch and leaching cell approaches were used to study the effect of a range of
inorganic and organic ligands on the distribution of aluminium (Al) between
the exchangeable and solution phase and to assess the ability of the ligands
to mobilise aluminium in an acidic red earth (Calcic Rhodoxeralf). Anions were
chosen to represent a range of potential abilities to form complexes with Al.
They included chloride, fluoride, citrate, salicylate, 2,3-dihydroxybenzoic
acid, catechol, and 2 different coal-derived fulvates. Batch experiments,
using a 1 : 5 soil : solution ratio, showed that citrate, 2,3-dihydroxybenzoic
acid, and fluoride had a similar effect on Al sorption and speciation. These
anions were effective in decreasing the amount of exchangeable and sorbed Al
and increased the amount of complexed Al in solution. In the soil solution,
very little Al was in the uncomplexed toxic form
(Al3+). Results from the batch
experiments may not necessarily give a good indication of the behaviour of Al
in the soil at realistic moisture contents. Therefore, those anions that
showed the best capacity to remove exchangeable Al and decrease the
concentration of toxic Al3+ in the
solution were used in leaching cell experiments. These results showed that
citrate, 2,3-dihydroxybenzoic acid, and the coal-derived fulvates can
significantly decrease exchangeable Al, citrate being the most effective.
Citrate and 2,3-dihydroxybenzoic acid resulted in significant amounts of Al
being leached from the soil, whereas fluoride and the fulvates resulted in
only slightly more Al leaching than chloride. Although the fulvates can remove
some of the exchangeable Al, it was not leached from the soil. Both the batch
and leaching cell techniques do allow the screening of compounds to decrease
the concentration of toxic Al3+on
the cation exchange complex of the soil.
Plant growth promotion of wheat inoculated with Penicillium radicum
sp. nov.
Authors: Whitelaw M. A. , Harden T. J. , Bender G. L.
Published: August 2004

A phosphate-solubilising isolate of Penicillium radicum
(sp. nov.) was used to inoculate wheat
(Triticum aestivum cv. Dollarbird) in a glasshouse
experiment and a field trial, using low pH soils at 5 levels of phosphate
application. When data for all phosphate application levels were combined,
inoculation by P. radicum resulted in 14%
increases in wheat yield in the field trial and increases in both phosphate
uptake (10%) and yield (9%) in the glasshouse. In the
glasshouse, the response to inoculation was higher at the nil phosphate
application level (17%) than for the combined phosphate application
levels (9%). This negative interaction indicates that growth promotion
could be partially due to soil phosphate solubilisation by the fungus, with a
greater response for soils with lower available P. However, other plant-growth
promotion mechanisms may also be involved.
Adsorbed ion activity coefficients in K - Ca exchange on soil fractions derived from volcanic materials
Authors: Escudey M. , Diaz P. , Foerster J. E. , Galindo G.
Published: August 2004

The effects of temperature and iron oxide coatings on the adsorbed ion
activity coefficients obtained by the Gaines–Thomas treatment for the
K–Ca exchange equilibria on clay fractions of 3 Chilean Andisols were
studied. The comparison with the values calculated through the Vanselow
approach, using conversion equations, was also considered.
Adsorbed Ca activity coefficient curves present a similar shape for the
Gaines–Thomas and Vanselow approaches; for K, maxima were observed only
when the Gaines–Thomas treatment was used.
Iron oxide coated samples showed higher adsorbed ion activity coefficients
than allophanic samples. The adsorbed K activity coefficients increased when
temperature increased from 4°C to 26·5°C, but only a slight
effect on Ca ions was observed.
In both types of samples, the presence of 3 possible selective sites was
detected: K-selective sites, Ca-selective sites, and sites where K–Ca
competition occurs.
Aggregation of soil by fungal hyphae
Authors: Tisdall J. M. , Smith S. E. , Rengasamy P.
Published: August 2004

Several authors have proposed that soils are made up of aggregates of various
sizes, stabilised by different organic and inorganic materials. Fungal hyphae
have been shown to bind microaggregates (<250 µm diameter) into
macroaggregates (>250 µm diameter). This paper examines the
aggregation of soil clay by saprophytic
(Rhizoctonia solani and
Hyalodendron sp.) and mycorrhizal
(Hymenoscyphus ericae and Hebeloma
sp.) fungi. The results support the hypothesis that fungal hyphae bring
mineral particles and organic materials together to form stable
microaggregates at least <2µm, and enmesh microaggregates into stable
aggregates >50 µm diameter.
Testing gypsum requirements for dryland cropping on a Red-Brown Earth
Authors: Ellington A. , Badawy N. S. , Ganning G. W.
Published: August 2004

Gypsum requirements of a Red-Brown Earth used for dryland cropping were
determined by 2 methods: those of the State Chemistry Laboratory (SCL) and of
the Institute for Sustainable Irrigated Agriculture (ISIA). These are based,
respectively, on exchangeable cations of soil by the Tucker method, and on
water-soluble cations in a 1:5 water extract of soil. Information was also
gained on longevity of gypsum effects on soil.
Gypsum was applied to plots at rates 0·5, 1, and 2 times that predicted
by ISIA, whereas the SCL method predicted that no gypsum was required. After 2
years, plots were split and the 3 rates of gypsum were either applied to soil
previously untreated with gypsum, or re-applied to the soil treated 2 years
before.
According to the SCL test, the 0–10 cm soil depth of the Red-Brown Earth
was not sodic (ESP <6), it was slightly magnesic (EMgP >25), and
required no gypsum. However, it was found that gypsum lowered ESP, EMgP, and
clay dispersion, with some effects extending into the 10–20 cm soil
depth.
With the ISIA method, the 0–10 cm soil depth was classed as low-sodic,
but potentially dispersive; it required 2·5 t/ha of gypsum if soil
was cultivated, but no gypsum if it was direct-drilled or was under pasture.
One year after application, only the highest rate of gypsum (5 t/ha)
significantly (P < 0·001) raised the
electrolyte concentration of the soil suspension, although all rates reduced
(P < 0·001) SAR, and the 2 higher rates
reduced (P < 0·01) clay dispersion. However,
these effects had disappeared after Year 3.
There were significant increases in crop yields due to gypsum treatment in
Year 1 (0·5–0·9 t/ha, P <
0·01) and Year 2 (0·3 t/ha, P <
0·001), but no response in Year 3. Fungal diseases seemed to reduce
wheat responses, and the highest rate of gypsum caused chlorosis of lupins.
Judging by crop performance, the ISIA method predicted an optimal rate of
gypsum for the 0–10 cm layer of this soil type. The SCL prediction was
also only for the 0–10 cm layer, but had it been used for deeper layers
in the profile (the original intention for the technique), it would have given
a recommendation not very different from the ISIA method.