bluuebunny/crossref_metadata_2025 huggingface dataset:
Geochemical influences on metal partitioning in contaminated estuarine sediments
Authors: Simpson Stuart L. , Rochford Louisa , Birch Gavin F.
Published: September 2002

Stormwater runoff has resulted in heavy metal contamination throughout much of
the Port Jackson estuary, Sydney, Australia. Metal partitioning was
investigated in the benthic estuarine sediments of Iron Cove, an off-channel
embayment of Port Jackson. Contamination was greatest near the stormwater
canal, where sediments were anoxic and contained high concentrations of
sulfide in the porewater. Away from the canal a layer of non-cohesive,
sub-oxic surficial sediment containing high dissolved iron was found
overlaying a more cohesive substratum. At all sites, porewater Cd, Cu, Ni, Pb
and Zn were <2.5 g L–1, and negligible metal
release was observed upon sediment resuspension. According to water quality
guidelines, the ecological risk posed by dissolved metals from the Iron Cove
sediments is low. Estimated fluxes of Cd, Cu, Ni, Pb and Zn from the sediments
were calculated to be <0.2 mol m–2
day–1. The rapid oxidation then hydrolysis of
iron(II) in porewaters caused a drop in pH and the formation of iron hydroxide
precipitate. These processes may affect dissolved metal concentrations; hence,
oxidation of samples must be avoided during sampling and extraction
procedures. Sediment-bound zinc was the metal most easily mobilized.
Molecular phylogeny of the spiny lobster genus Panulirus (Decapoda: Palinuridae)
Authors: Ptacek Margaret B. , Sarver Shane K. , Childress Michael J. , Herrnkind William F.
Published: September 2002

Phylogenetic relationships among all described species and four subspecies
(total of 21 taxa) of the spiny lobster genus Panulirus
White, 1847, were examined with nucleotide sequence data from portions of two
mitochondrial genes, large-subunit ribosomal RNA (16S) and cytochrome oxidase
subunit I (COI). Multiple sequence alignments were subjected to
maximum-parsimony, neighbour-joining, and maximum-likelihood analysis with
Jasus edwardsii as the outgroup. Two major lineages
within Panulirus were recovered by all three methods for
both the 16S and COI alignments analysed separately and for the combined
alignment. The first lineage included all species of
Panulirus classified as Groups I and II by previous
morphologically based definitions. The second included all species classified
as Groups III and IV. Relationships within major lineages were not well
resolved; the molecular phylogeny did not support separation of Group I from
Group II or of Group III from Group IV. The degree of sequence divergence
between different pairs of species was higher in pairwise comparisons between
species in Group I/II (16S: 2.8–19.4%; COI:
12.4–31.8%) than in those between species in Group III/IV
(16S: 5.3–13.2%; COI: 12.6–19.6%). This pattern
suggests that the Group I/II lineage may represent an earlier radiation of
species within Panulirus.
Captive biology of the pelagic stingray, Dasyatis violacea (Bonaparte, 1832)
Authors: Mollet H. F. , Ezcurra J. M. , O'Sullivan J. B.
Published: September 2002

Pelagic stingrays, Dasyatis violacea, were collected in
southern California in summer–autumn 1994–97. The smallest,
40–45 cm disc width (DW) and 2 kg, were estimated to approach age two.
In captive growth and feeding experiments from March 1995 to August 2000, the
largest male reached 68 cm DW and 12 kg at estimated age 7 years, and the
largest female reached 96 cm DW and 49 kg at estimated age 9 years. The growth
data could be fitted with both Gompertz and von Bertalanffy growth functions,
but the former produced more reasonable values for size at birth, maximum
size, and longevity. Consumption of squid was 6–7% of body mass
(BM) per day for juveniles 2 years old and decreased to 1.25% BM
day–1 for adults. Food intake for adults was
seasonal, with 2 cycles per year with a maximum of ~2.0% and a minimum
of 1.0–0.5% BM day–1 from July to
October 1998. The data for gross conversion efficiency
(K1, based on energy values),
collected at 20°C with daily feeding to satiation, could be fitted with a
linear regression in the estimated mean age range of 3–6 years
(K1 = 0.37 – 0.055
Age).
Normal bacterial flora of the spiny lobster Panulirus argus and its possible role in shell disease
Authors: Porter Lauren , Butler IV Mark , Reeves Robert H.
Published: September 2002

Recent surveys of the Caribbean spiny lobster
(Panulirus argus) in the Florida Keys and the Dry
Tortugas revealed the presence of necrotic carapace lesions, which are
commonly associated with bacterial shell disease in other crustaceans. To
determine the etiology of these lesions, we obtained bacterial samples from
diseased and nondiseased lobsters. Bacteria from these samples were isolated
and identified by 16S ribosomal RNA sequencing. At least 600 bases of the 16S
rRNA gene were aligned with sequences from known strains of marine bacteria.
The analysis showed that the majority of the strains isolated from diseased
and nondiseased lobsters are within the Vibrionaceae, a common family of
marine bacteria. The majority of isolates identified as
Vibrio species are clustered in a monophyletic group
that does not include any of the known Vibrio species. Genbank BLAST analysis
also confirmed these isolates as Vibrio and confirmed
that they are not closely related to any known
Vibrio species. These results suggest that the normal
flora of P. argus is unique. The association of these
bacteria both with lesions and with nondiseased animals suggests that the
natural flora is responsible for the lesions seen in
P. argus.
Effects of frontal eddies on the distribution and food availability of anchovy larvae in the Kuroshio Extension
Authors: Okazaki Yuji , Nakata Hideaki , Kimura Shingo
Published: September 2002

The frontal area of the Kuroshio Extension was observed in June 1997 and May
1999. In 1997, anchovy larvae were most abundant in a frontal region of the
eddy generated in association with a northward intrusion of warm water from
the Kuroshio Extension. High nutrient concentrations apparently overlapped
with the larval aggregation, while chlorophyll-a
concentration was rather low all over the region. In 1999, observations were
made along a two-day trajectory of a drifter released from the eddy centre,
which was recognized by a satellite image. Chlorophyll-a
concentration was high in the eddy centre but decreased with time. By
contrast, abundance of copepod nauplii in the eddy increased with time, and
eventually doubled. These results suggest that the frontal eddy contributes to
both copepod production and horizontal entrainment or aggregation of anchovy
larvae in the frontal region. The frontal eddy possibly benefits the growth
and survival of fish larvae in the oligotrophic oceanic water of the Kuroshio
Extension region.
A revision of Indo-Pacific Bembrops, family Percophidae (suborder Trachinoidei)
Authors: Thompson Bruce A. , Suttkus Royal D.
Published: September 2002

A recent study recognized six species of Bembrops from
the Indo–Pacific: B. caudimacula,
B. curvatura, B. filiferus,
B. morelandi, B. nematopterus and
B. platyrhynchus. Now, two species are elevated;
B. adenensis is removed from the synonymy
ofB. caudimacula and
B. philippinus from
B. platyrhynchus. In addition, a new sister species to
B. adenensis is recognized from southern Indonesia and
the Philippine Islands, bringing the total number of Indo–Pacific
Bembrops to nine. Many early records of
B. caudimacula are shown to be
B. curvatura, a species not described until 1952.
Information is presented on meristics, morphometrics, colour pattern and
sexual dimorphism for the Indo–Pacific species, with comparisons with
the ten Atlantic forms. B. adenensis and the new species
are the only two members of the genus with a complete suborbital canal.
B. nematopterus, elsewhere considered to be a synonym of
either B. platyrhynchus or
caudimacula, is a valid species found along the Indian
Ocean coast of Africa. New information is provided on the distribution of most
Indo–Pacific Bembrops species.
Bembrops morelandi, considered a New Zealand endemic, is
reported for the first time from Australia. Geographic variation in body
pigment pattern is presented for Bembrops caudimacula,
B. filiferus and B. philippinus.
Resource partitioning among four butterflyfish species in the Red Sea
Authors: Zekeria Z. A. , Dawit Y. , Ghebremedhin S. , Naser M. , Videler J. J.
Published: September 2002

Feeding habits and territorial behaviour of four sympatric Red Sea
butterflyfishes were investigated in Eritrean coastal waters. Individual bite
rates and types of food consumed were recorded. Stomach contents of 125
specimens were analysed in the laboratory. The food items in the stomach were
sorted and their volume estimated. The four species showed marked variation in
their food preferences and feeding habits. The most abundant,
Chaetodon larvatus, an obligate corallivore, forms
monogamous pairs. Each pair defends a relatively small territory against
conspecifics and C. semilarvatus. The latter species
also feeds on scleractinian corals but is solitary or lives in small
aggregations. The third species, Heniochus intermedius,
feeds on non-coralline benthic invertebrates (mainly polychaetes); it usually
lives in pairs or in aggregations of up to 24 individuals. Both
C. semilarvatus and H. intermedius
occupy undefended and overlapping home ranges. The least abundant species,
C. mesoleucos, forms monogamous pairs, defends a
territory and feeds mainly on non-coralline benthic invertebrates (mainly
nematodes and polychaetes). The four species co-exist in the same habitat
where they partition the food resources. Both
C. larvatus and C. semilarvatus
feed on scleractinian corals, but at different times;
C. larvatus was observed to feed only during daytime,
but C. semilarvatus feeds by day and night.
Taxonomy and mitochondrial sequence evolution in non-diadromous species of Rhinogobius (Teleostei: Gobiidae) of Hainan Island, southern China
Authors: Chen I-Shiung , Miller Peter J. , Wu Han Ling , Fang Lee-Shing
Published: September 2002

Collections of the West-Pacific freshwater gobiid genus,
Rhinogobius Gill, 1859, from Hainan Island, southern
China, were examined morphologically and their taxonomic status revised
according to meristic criteria and colouration. As well as a confirmation of
the presence of R. leavelli, a further four species with
a non-diadromous life history are here described as new to science under the
following names: Rhinogobius changjiangensis n. sp.,
R. linshuiensis n. sp.,
R. nandujiangensis n. sp., and
R. wangchuangensis n. sp., inhabiting different river
basins on the island. To compare taxonomic status and evolutionary history of
these species with Chinese freshwater species of
Rhinogobius, the complete mitochondrial control region
was amplified and sequenced for three of the new species, a non-diadromous
species from southern China (R. duospilus), and two
amphidromous species, R. leavelli from southern China
(including Hainan) and R. maculafasciatus from Taiwan.
The resulting molecular data indicate a high level of genetic divergence
between these putative morphological species, and the phylogenetic
reconstructions from both distance and discrete methods suggest that the
endemic non-diadromous species of Hainan evolved from a common non-diadromous
ancestor, probably during more than one period of marine regression.
Using tyres as shelters for the protection of juvenile spiny lobsters, Panulirus argus, or as a fishing gear for adults
Authors: Losada-Tosteson Vanessa , Posada Juan M.
Published: September 2002

This study evaluated use of tyres (as ‘casitas,’ not currently
used in Venezuela) as shelters for juvenile lobsters or as a fishing gear for
adults. In surveys at the Los Roques Archipelago National Park, eight
‘tyre casitas’ (area covered 0.44–0.57
m2 ) and eight wire traps (area covered 1.60–1.98
m2) were randomly placed, 15 m apart, on a 60-×
60-m area of sandy bottom covered with mobile brown algae (depth 1.5 m). The
same arrangement was repeated, 400 m away, on a sea-grass bottom. The
structures were checked and rearranged weekly, for eight weeks. Lobsters
caught were measured, weighed, and released 2–5 km away. Of the 117
lobsters caught, 70.9% came from traps (size range 74.1–153.0 mm
CL) and 29.1% from the tyre casitas (6.1–127.1 mm CL). Only 14
(11.9%) were of minimum legal landing size (120 mm CL), and 12
(85.7%) of these were caught in traps. Of the 83 lobsters captured in
traps, 51 (61.4%) came from the sea-grass bottom, whereas of the 34
captured in tyre casitas, 27 (79.4%) came from the sandy bottom. The
tyre casitas used seem more efficient as shelter for juveniles than as a
fishing device for adults.
Larval culture of the European spiny lobster Palinurus elephas
Authors: Kittaka Jiro , Kudo Ryoji , Onoda Susumu , Kanemaru Kazutami , Mercer John P.
Published: September 2002

The development of phyllosomas of the European spiny
lobsterPalinurus elephas was examined in recirculating
culture systems. Approximately 2000 newly hatched phyllosomas were introduced
into each of three 100-L circular culture containers. Two of the containers, A
and B, shared a filter; container C had a separate system of similar design.
Hatched larvae of the sailfin sandfish
Arctoscopus japonicus were fed to phyllosomas in
container A, and pieces of the gonad of the mussel
Mytilus edulis to those in container B. Phyllosomas in
container C received both foods for the first 24 days; thereafter
A. japonicus comprised their sole diet. Water
temperature was maintained at 19–20˚C in containers A and B and at
16–18˚C in container C. Two individuals from container A and 10
from container C metamorphosed into pueruli after six instars at 65 and 69
days respectively, whereas earlier trials involved an estimated nine instars
to metamorphosis after 132 days. Larvae thus cultivated were used to describe,
for the first time, the morphological development of
Palinurus elephas phyllosomas through metamorphosis to
the puerulus stage. Fish larvae, such as A. japonicus
may be an important dietary component for cultivation of palinurid
phyllosomas.
Marine reserves for Caribbean spiny lobster: empirical evaluation and theoretical metapopulation recruitment dynamics
Authors: Lipcius Romuald N. , Stockhausen William T. , Eggleston David B.
Published: September 2002

Field data on spiny-lobster abundance, habitat quality, and hydrodynamic
transport patterns for a reserve (ECLSP) and three exploited sites (CI, EI,
LSI) were used to assess reserve success in reducing fishing mortality and
increasing theoretical metapopulation recruitment. Fishing mortality was
estimated empirically by quantification of lobster density at ECLSP and the
three exploited sites before and after the start of the fishing season in two
years. Fishing mortality was estimated to be 47–98% lower at the
reserve. Using a circulation model , we theoretically assessed effectiveness
of ECLSP and nominal reserves at the exploited sites in augmenting recruitment
through redistribution of larvae to all sites. Larvae discharged from ECLSP
and EI recruited throughout Exuma Sound, whereas those from LSI and CI
recruited only to CI and LSI. Hence, only reserves at EI and ECLSP would be
suitable for metapopulation recruitment. In selecting an optimal reserve for
metapopulation recruitment, use of information on habitat quality or adult
density did not yield a higher probability of success than did determining the
reserve location by chance. The only successful strategy was one that used
information on transport processes. Designation of effective marine reserves
therefore requires careful attention to metapopulation dynamics and
recruitment processes.
Distribution of the pelagic stingray, Dasyatis violacea (Bonaparte, 1832), off California, Central America, and worldwide
Authors: Mollet H. F.
Published: September 2002

The pelagic stingray, Dasyatis violacea (Bonaparte,
1832), is nearly worldwide in subtropical and tropical seas, and also at
temperate latitudes. It is found in the top 100 m over deep water. This paper
presents the pelagic stingray distribution off California from by-catch of the
California drift gill-net fishery for swordfish during 1990–99 and
research longline cruises for pelagic sharks in the southern California Bight.
Field data of 28 specimens in the Scripps Institute of Oceanography collection
suggested that females in the eastern Pacific population gives birth in warmer
water in winter off the coast of Central America and then migrate to higher
latitudes including southern California. A worldwide distribution map has been
prepared, based on by-catch data from the longline fishery in the central
north Pacific, the New Zealand and Australia Exclusive Economic Zone, and
location reports of new captures in the literature and personal
communications.
Seasonal dynamics of plankton communities and water chemistry in a eutrophic wetland (Lake Monger, Western Australia): implications for biomanipulation
Authors: Lund Mark A. , Davis Jennifer A.
Published: September 2002

In a large (70 ha) shallow (<2m deep)
eutrophic wetland investigated between November 1988 and October 1989, there
were marked seasonal changes in water quality and the composition of
zooplankton, and to a lesser extent phytoplankton communities, with three
distinct groupings evident: summer, winter–spring and autumn. Summer
conditions were characterized by high levels of total P (689198 ˜g L
–1 ), N limitation, blooms of
Microcystis aeruginosa (mean chlorophyll
a = 46630 ˜g L
–1 ) and zooplankton communities dominated by
cyclopoid copepods (Mesocyclops sp. and
Microcyclops sp.). Winter–spring conditions were
characterized by Secchi disk transparencies to the bed (chlorophyll
a <50 ˜g L –1 ),
low total P (7140 ˜g L–1 ) and zooplankton
communities dominated byDaphnia carinata King. Autumn
conditions represented an intermediate state between these two. Significant
linear relationships were recorded between chlorophyll a
and total P and between chlorophyll a and
D. carinata. Abundances of hemipteran predators
(Anisops sp.) were correlated with
D. carinata, but the relationship did not appear to be
causal. The decline in D. carinata in summer was
attributed to food limitation. Reductions in nutrient inputs to the lake in
1990–91, resulted in improved water quality and high abundances of
D. carinata during summer.
Changes in the diet of the Australasian gannet (Morus serrator) in response to the 1998 mortality of pilchards (Sardinops sagax)
Authors: Bunce A. , Norman F. I.
Published: September 2002

The diet of Australasian gannets
(Morus serrator) breeding in Port Phillip Bay was
investigated before and after a mass mortality of pilchards (Sardinops sagax)
in southern Australian waters in 1998. Gannets usually feed on inshore pelagic
schooling fish, such as pilchards and barracouta
(Thyrsites atun), and to a lesser extent on other
species. Pilchards represented ~60% of the gannet diet examined before
the spread of pilchard deaths into Victorian waters, but this component
declined to 5% following the mortality event. This reduction was
compensated by a substantial increase in the amount of barracouta taken,
supporting the view that the gannet is a flexible forager. However, the 1998
mortality of pilchards is likely to have wider implications since pilchards
are an important prey for other piscivorous fish, seabirds and marine mammals.
Remote sensing of seabed types in the Australian South East Fishery; development and application of normal incident acoustic techniques and associated 'ground truthing'
Authors: Kloser R. J. , Bax N. J. , Ryan T. , Williams A. , Barker B. A.
Published: September 2002

Calibrated acoustic backscattering measurements using 12, 38 and 120 kHz were
collected over depths of 30–230 m, together with benthic epi- and
in-fauna, sediments, photographs and video data. Each acoustic ping was
envelope detected and digitized by echo sounder to include both the first and
second echoes, and specifically designed software removed signal biases. A
reference set of distinct habitat types at different depths was established,
and a simple classification of the seabed combined both biological and
geological attributes. Four seabed types were identified as having broad
biological and geological significance;the simple acoustic indices could
discriminate three of these at a single frequency. This demonstrates that the
acoustic indices are not directly related to specific seabed properties but to
a combination of seabed hardness and roughness attributes at a particular
sampling frequency. The acoustic-derived maps have greater detail of seabed
structure than previously described by sediment surveys and fishers’
interpretation. The collection of calibrated digital acoustic data at multiple
frequencies and the creation of reference seabed sites will ensure that new
shape-and energy-based feature extraction methods on the ping-based data can
begin to unravel the complexities of the seabed. The methods described can be
transferred to higher-resolution swath-mapping acoustic-sampling devices such
as digital side-scan sonars and multi-beam echo sounders.
Changes in soluble and membrane-bound isoforms of calcium-calmodulin-dependent and -independent NAD+ kinase, during the culture of after-ripened and dormant seeds of Avena sativa
Authors: Gallais Stéphane , Pou de Crescenzo Marie-Anne , Laval-Martin Danielle L.
Published: September 2002

Activities of the soluble and membrane-boundisoforms of Ca 2+ calmodulin (CaCam)-dependent and-independent NAD + kinases, were followed in theembryos during the culture of dormant (D) and after-ripened (AR) seeds ofAvena sativa L. Embryos of D and AR seeds differ mainly in the evolution ofmembrane-bound activities, the majority of which are CaCam-dependent andlinked to mitochondria. The in vivo application ofgibberellic acid, CaCl2 andH2O2, which enhanced germination,induced an enhancement of all CaCam-dependent isoforms. Trifluoperazine (TFP),a calmodulin antagonist, greatly enhanced all CaCam-dependent isoforms andabolished the differences between the NAD + kinaseactivities of the two kinds of embryo. In addition, TFP rendered embryosunable to resume axis growth, probably due to pleiotropic effects. In contrastto H2O2, the reducing agentdithiothreitol diminished the soluble CaCam-dependent enzyme and blocked thegermination of both types of seed, whereas it increased the dependentmembrane-bound activities. The results demonstrate (1) that theCaCam-dependent NAD + kinase isoforms —amongst which is the isoform bound to mitochondrial membranes — play animportant role at the end of sensu stricto germinationand during the following growth of Avena sativa; and (2)that an excess of activity of these isoforms could be markers of stress orlethal conditions.
The herbicidally active compound N-2-(5-chloro-pyridyl) aminomethylene bisphosphonic acid acts by inhibiting both glutamine and aromatic amino acid biosynthesis
Authors: Forlani Giuseppe , Lejczak Barbara , Kafarski Pawel
Published: September 2002

The effect of the herbicidally active compound
N-2-(5-chloro-pyridyl)aminomethylene bisphosphonic acid
(Cl-pyr-AMBPA), previously found in vitro to inhibit the
activity of the first enzyme in the shikimate pathway
3-deoxy-D-arabino-heptulosonate-7-phosphate synthase,
was investigated in vivo on
suspension cultured cells of Nicotiana plumbaginifolia
Viviani. Amino acid pool measurement showed an actual reduction of tyrosine,
tryptophan and phenylalanine level following the addition of the compound to
the growth medium. However, an even stronger effect was noticed for other
amino acids, mainly glutamine. When the activity of the enzymes involved in
the glutamate cycle was measured in the presence of Cl-pyr-AMBPA, glutamate
synthase was unaffected, while glutamine synthetase was significantly
inhibited. Contrary to the herbicide phosphinothricin, the inhibitor bound
reversibly to the enzyme. Kinetic analysis accounted for an inhibition of
uncompetitive type with respect to ammonium, glutamate and ATP,
withKivalues of 113, 97 and 39 M,
respectively. Only the exogenous supply of a mixture of glutamine and aromatic
amino acids relieved cell growth inhibition, suggesting that the phytotoxic
properties of Cl-pyr-AMBPA are due to inhibition of key enzymes in both the
corresponding pathways.
Agrobacterium cells as microprojectile coating: a novel approach to enhance stable transformation rates in strawberry
Authors: Mesa Macarena Cordero de , Jiménez-Bermúdez Silvia , Pliego-Alfaro Fernando , Quesada Miguel A. , Mercado José A.
Published: September 2002

The effect of combining Agrobacterium tumefaciens
infection and biolistic bombardment on the transformation of strawberry
(Fragaria × ananassa Duch.)
cv. Chandler, was evaluated. Bombarding leaf explants with uncoated gold
particles followed by Agrobacterium infection did not
improve transformation, and yielded similar percentages of shoot regeneration
in the presence of kanamycin in bombarded and non-bombarded explants
(7.2%). In a novel approximation, gold particles were coated with
Agrobacterium cells and used to bombard leaf explants.
Helium pressures of 4.5, 6.2 and 7.6 MPa and target distances of 3 and 9 cm
were tested. An average of 96.2% of the explants showed
β-glucuronidase (GUS) expression 15 d after bombardment, in comparison
with 26.6% in explants bombarded with gold particles coated with the
plasmid pGUSINT or 58.3% in non-bombarded
Agrobacterium-infected explants. After 25 weeks of
culture, the highest transformation frequency was obtained using a 6.2 MPa
helium pressure and 3 cm target distance, yielding 69%
kanamycin-resistant explants and a final transformation fre-quency of
20.7%. These values were 4.5 times higher for kanamycin-resistant
explants (69% with biolistic vs 16% with
Agrobacterium infection) and 2.9 times higher for
transformation frequency (20.7 vs 7%,) compared
with those obtained with standard Agrobacterium
transformation procedures (Barceló et al. 1998,
Plant Cell, Tiss. Org. Cult. 54,
29–36). More than 15 independent transgenic plants obtained by the
Agrobacterium-coated particle system were acclimatized
and confirmed as transgenics by GUS activity and PCR. Segregation analysis of
kanamycin resistance has been performed in seven independent lines, three of
which contained a single insertion of the T-DNA.
Cloning and molecular features of cytosolic fructose-1,6-bisphosphatase from pea
Authors: Cazalis Rolland , Cazalis Rolland , Pagano Eduardo , Pagano Eduardo , Gorgé Julio López , Gorgé Julio López , Chueca Ana , Chueca Ana
Published: September 2002

A cDNA clone encoding for pea (Pisum sativum L.)
cytosolic fructose-1,6-bisphosphatase (E.C. 3.1.3.11) has been isolated by
reverse transcription-polymerase chain reaction of the total mRNA. The
sequence analysis displayed a 341-amino acid protein of about 37300 Da
molecular mass, corresponding to the subunit of this homotetrameric enzyme; it
showed about 80% homology with the other ten higher plant cytosolic
FBPases sequenced so far. The enzyme displayed a strong transcriptional
expression in green organs (sessile and petioled leaves, stem, pod and grain),
and poor expression in root and senescent basal leaves. It is noteworthy the
high FBPase transcriptional expression in pod, which displays up to 4-fold
higher content of FBPase-specific mRNA than that of root. The mRNA related to
cytosolic FBPase was detected after 24 h continuous illumination of
24-h-dark-grown seedlings; this light-induced transcriptional expression is
slower than that of chloroplast FBPase, which appears soon after 2 h light. In
both cases the corresponding mRNAs disappeared when the light was turned off.
The translational expression was also manifested, both as FBPase protein and
activity, after 24 h illumination. This delay in the expression of cytosolic
FBPase with respect to that of the plastidic enzyme can be interpreted as an
indirect effect induced by a metabolite of the photosynthetic carbon pathway,
rather than a direct effect of light on the DNA-expression mechanism. Pea
cytosolic FBPase was not activated by dithiothreitol, with or without coupling
to thioredoxins f or m. The enzyme
showed a half-life of 6 h.
The influence of nitrogen supply on growth and internal recycling of nitrogen in young Nothofagus fusca trees
Authors: Stephens David W. , Millard Peter , Turnbull Matthew H. , Whitehead David
Published: September 2002

The effect of nitrogen supply on biomass, and nitrogen storage and
remobilisation, was investigated in young
Nothofagus fusca (Hook f.) Oerst. trees growing in pots
while irrigated with nutrient solutions containing 0.5 (low nitrogen, LN), 3
(medium nitrogen, MN) and 6 (high nitrogen, HN) mM nitrogen. During the first
annual growth cycle, nitrogen supply was labelled with
15 N. By mid-autumn of the second annual cycle, dry
weights of whole tree, stem, leaves and roots for trees in the HN and MN
treatments were over 10-fold greater than the weights for trees in the LN
treatment. Nitrogen was stored in roots and remobilised for new leaf and stem
growth during spring. In summer, remobilised nitrogen comprised approximately
40% of the total nitrogen in leaves and stems for trees in all
treatments. Nitrogen uptake for trees in the HN and MN treatments continued
during the winter dormant period, and accounted for approximately half the
total nitrogen acquired during the first cycle. Storage of nitrogen in roots
(a deciduous characteristic), and the independence of nitrogen remobilisation
from leaf senescence and significant winter uptake of nitrogen (both evergreen
characteristics), suggest that the leaf phenology of
N. fusca allows the species to maximise nitrogen
acquisition from low fertility soils to enhance productivity.
Competitive inhibitor-dissected histochemistry of the peroxidase responsible for syringyl lignin biosynthesis in Zinnia elegans xylem
Authors: Barceló Alfonso Ros , Pomar F. , Pedreño M.A.
Published: September 2002

The lignifying xylem from Zinnia elegans hypocotyls
gives an intense reaction with the MÄule reagent, which is specific for
syringyl moieties. The presence of syringyl moieties in the
β-O-4 lignin fraction from
Z. elegans cell walls was confirmed by thioacidolysis,
which gave, as main products, the thioethylated monomers arising from
aryl-glycerol-β-aryl ether structures derived from coniferyl and sinapyl
alcohols. The guaiacyl/syringyl molar ratio for this lignin fraction was
43/57. Besides β-O-4 syringyl lignins,
lignifying Z. elegans hypocotyls also contain a basic
peroxidase capable of oxidizing syringyl moieties, such as those present in
sinapyl alcohol and syringaldazine, the latter a chromogenic substrate
containing the syringyl group specific for angiosperm lignins. Competitive
inhibitor-dissected histochemistry of the developing xylem revealed that the
stain for syringaldazine oxidase was restricted to the two or three outermost
developing (lignifying) xylem cell layers, and which responded to competitive
inhibitors, such as ferulic acid and ferrocyanide, and to suicide substrates,
such as m-chloroperoxybenzoic acid, in a similar way to
the Z. elegans basic peroxidase. From these results, we
conclude that this Z. elegans basic peroxidase is found
at the precise time and place where lignification is occurring, and emerges as
the key enzyme involved in the polymerization of sinapyl alcohol and
responsible for syringyl-type lignin assembly.
Correlations between oxygen isotope ratios of wood constituents of Quercus and Pinus samples from around the world
Authors: Barbour Margaret M. , Andrews T. John , Farquhar Graham D.
Published: September 2002

The oxygen isotope compositions of three wood constituents (the
solvent-extractable portion, lignin and α-cellulose) were measured for
samples collected from Quercus and
Pinus trees around the world. Among
Pinus samples all wood constituents were positively
related to modelled δ18O of source water at the
site, while among Quercus samples whole wood, lignin and
α-cellulose showed positive relationships. The data support the
hypothesis that many oxygen atoms in lignin exchanged with unenriched stem
water during synthesis, rather than retaining the full isotopic signal from
the molecular oxygen added during hydroxylation of the aromatic ring. The data
also suggest that extraction of α-cellulose from wood samples is
unnecessary for isotope studies looking at correlations with site parameters.
Altered cytokinin distribution in the shootless maize mutant ed*41
Authors: Chiappetta Adriana , de Witte Walter , Racchi Milvia L. , Bitonti Maria B. , van Onckelen Henri , Innocenti Anna M.
Published: September 2002

The distribution of cytokinins is strongly altered in seedlings of the
shootless ed*41 mutant of maize
(Zea mays L.), compared with wild-type.
Immunolocalisation of zeatin and analysis of cytokinin levels clearly indicate
that these hormones are not present in the shoot apex zone of the mutant.
Since an anomalous differentiation of vascular tissues has also been observed
in the mutant, a major role of vascular connection in hormone translocation
affecting development of the shoot apical meristem is proposed.
Immunolocalisation of zeatin was confined to the root cap, cortex and vascular
tissues of both mutant and wild-type seedlings suggesting a tissue-specific
synthesis of this hormone in the root. A time-course of cytokinin distribution
in the wild-type developing shoot provided evidence that the tunica and corpus
zones become competent to respond to cytokinins in subsequent periods, very
probably in conjunction with photomorphogenesis. On the contrary, this pathway
is totally disrupted in the mutant. Taken together, the data point to a
relationship between the ed*41 mutation, inadequate
vascular connection and disrupted hormone translocation.
Ion fluxes considered in terms of membrane-surface electrical potentials
Authors: Kinraide Thomas B.
Published: September 2002

Ions transported through plasma membranes encounter electrical charges, and
associated electrical potentials, at the membrane surfaces. The ionic
composition of the tissue-bathing medium influences both the surface charge
density and the surface electrical potential. Changes in surface electrical
potential may affect ion transport by altering two components of the chemical
potential difference (Δµj ) of an ion
through the membrane. First, the surface activity of the transported ion will
change because of electrostatic attraction or repulsion. Second, the
surface-to-surface transmembrane potential difference will change. (This is
different from the bulk-phase-to-bulk-phase transmembrane potential difference
measured with microelectrodes.) These changes in the components of the
chemical potential may change the flux of an ion through the membrane even if
the surface-to-surface Δµj (equal to the
bulk-phase-to-bulk-phase Δµj ) remains
constant. The Goldman-Hodgkin-Katz (GHK) flux equation does not take into
account these surface-potential effects. The equation has been modified to
incorporate surface potentials computed by a Gouy-Chapman-Stern model and
surface ion activities computed by Nernst equations. The modified equation
(despite several additional deficiencies of the GHK model) successfully
predicts many transport phenomena not predicted by the standard GHK equation.
Thus electrostatic effects may account for saturation,
cis- and trans-inhibition,
rectification, voltage gating, shifts in voltage optima, and other phenomena
also attributable to other mechanisms.
Transient variations of water transfer induced by HgCl2 in excised roots of young maize plants: new data on the inhibition process
Authors: Gaspar Marília , Sissoëff Igor , Bousser Agnès , Roche Odile , Mahé Aline , Hoarau Jackson
Published: September 2002

Effects of low concentrations of HgCl2 on water
transport in excised maize (Zea mays L.) roots have been
monitored using a reliable system that permits continuous measurement of xylem
flux variations. The sap flow of exuding roots treated with 11 M
HgCl2 decreased by 80–90% in 10 min at
25˚C. Reversal of this inhibition was obtained using a sulfhydryl
[β-mercaptoethanol (β-ME)], or non-sulfhydryl
[ethylenediaminetetraacetate disodium salt (EDTA) and ferricyanide
(FeCy)] reagents. The time course of reversal was not the same in the
three cases. β-ME reversed quickly but not sustainably, whereas EDTA or
FeCy reversed slowly and sustainably. Using a cell pressure probe, turgor was
measured in the epidermis, and the first layer of cells in the cortex. Turgor
was considerably decreased in root epidermal cells after
HgCl2 treatment, suggesting that a normal root
water-transfer required an optimal turgor in these cells. Recovery of cell
turgor, was obtained satisfactorily with FeCy. In parallel with flux
measurements, histochemical analyses revealed a localization of Hg only in
peripheral root cells, suggesting that Hg targets are localized in the first
root cell layers. Involvement of water channels and/or ion transport in
the regulation of root water transport is discussed in the light of our data.
High-affinity potassium transport into wheat roots involves sodium - a role for HKT1?
Authors: Hayes Donna E. , Smith F. Andrew , Walker N. Alan
Published: September 2002

When a high-affinity K + transporter, HKT1, was
cloned from the roots of K + -starved wheat and
characterized, it seemed that the wheat high-affinity K
+ -uptake mechanism had been found. We review the
present status of HKT1 as a putative component of the wheat root high-affinity
mechanism, concluding that its role remains unclear, as it also does in
barley. We describe a new attempt to find its role. High-affinity K
+ transport in K +
-starved wheat seedling roots was studied by measuring K
+ -evoked depolarization. A single dominant
transport system was shown to carry K + , Rb
+ and Cs + , with a
binding site selectivity of about 1:1:0.15, respectively. We showed that the
small effect of 1 mM Na + on K
+ -evoked depolarization could be inhibition under
some conditions and stimulation under others. We confirmed that the effect of
1 mM Na + was to raise the K
+ affinity and to reduce transport velocity. In 0
Na + , high pH greatly reduced the K
+ -affinity, but in 1 mM Na
+ , high pH had no effect. So, in a given test, the
effect of Na + was to increase or decrease K
+ -evoked depolarization, depending on the test
[K + ] and the pH. We discuss
simplified, but plausible, kinetic models for this interaction of pH and Na
+ . The simplest model includes a K
+ symporter driven by H
+ or Na + depending on
their relative concentrations and affinities, with random binding order for
the two possible driver ions. This symporter would differ from HKT1 in its
selectivity for Rb + vs K
+ and in its inability to carry Na
+ alone. No role has been found for a symporter
resembling HKT1 as it is presently characterized by heterologous expression.
A simplified model for assessing critical parameters during associative 15N2 fixation between Azospirillum and wheat
Authors: Wood Craig C. , Islam Nazrul , Ritchie Raymond J. , Kennedy Ivan R.
Published: September 2002

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000
Detailed studies in field experiments have shown repeatedly that the transfer
of 15N2 fixed by diazotrophic
bacteria to wheat tissue is minimal. Here, a simple and convenient laboratory
co-culture model was designed to assess important features of the association
between Azospirillum brasilense and wheat, such as the rate of nitrogen
fixation (acetylene reduction), ammonia excretion from the bacterium and the
transfer of newly fixed 15N2 from
the associative diazotroph to the shoot tissue of wheat plants. After 70 h, in
this model, insignificant amounts of newly fixed N2 were
transferred from an ammonia-excreting strain of
A. brasilense to the shoot tissue of wheat. However,
when malate was added to the co-culture the 15N
enrichment of the shoot tissue increased 48-fold, indicating that 20%
of shoot N had been derived from N2 fixation. Thus, the
inability of the host plant to release carbon in the rhizosphere is a
significant constraint in the development of associative
N2-fixing systems. These specific results suggest that
wheat plants with an increased release of photosynthate to the rhizosphere
should be a priority for the future development of broad-acre agricultural
systems that are more self-sufficient for nitrogen nutrition. The simplicity
of the model for assessing the critical parameters of associative
15N2 fixation may allow
large-scale surveys of plant–bacterial interactions to be conducted and
a selection of improved associations for further study.
Mechanisms of micronutrient uptake in plants
Authors: Reid Robert J.
Published: September 2002

In plants, the elements Fe, Zn, Mn, Cu, Ni, B, Mo and Cl are considered to be
micronutrients essential for plant growth. Micronutrient uptake systems are
intrinsically more difficult to investigate than their macronutrient
counterparts because of the low fluxes involved. Currently, the mechanism of
transport for these micronutrients has not been clearly identified, except for
Cl. In the case of the trace metal micronutrients, uptake studies point to the
presence of high and low affinity transporters with broad substrate
specificity. The kinetics of these transporters is clouded by the failure of
many investigators to consider the effects of the electrostatic nature of the
plasma membrane on cation uptake. Recent work has helped to clarify the nature
of B movement across membranes and there is now evidence of a facilitated
transport system for B, in addition to its passive permeation directly through
the membrane. The uptake of Mo is known to be induced by
NO3 and inhibited by W, but little further information
is available on how Mo enters cells. In recent years, the emphasis has shifted
from physiological studies of micronutrient uptake to molecular investigations
of transporters cloned in plants and characterized in heterologous expression
systems. There is now a substantial catalogue of transporter genes, mostly for
trace metals, whose functions in plants have yet to be clearly defined.
Thermoprotective properties of small heat shock proteins from rice, tomato and Synechocystis sp. PCC6803 overexpressed in, and isolated from, Escherichia coli
Authors: Pike Carl S. , Grieve Joanne , Badger Murray R. , Price G. Dean
Published: September 2002

The present study forms part of a program investigating the role of small heat
shock proteins (sHSPs) in the acquired and transgenic thermotolerance of the
cyanobacterium Synechococcus PCC7942. The genes for
three minimally related sHSPs, OsHSP from
Oryza sativacytoplasm, tom111 from
Lycopersicon esculentumchloroplasts, and 6803 HSP from
Synechocystis sp. PCC6803, were cloned into the
Escherichia coli vector pTrcHisA, so as to produce an
N-terminal polyhistidine tag. The genes were transformed into
E. coli and overexpressed. The tagged HSPs were purified
(not completely in the case of tom111) by immobilised metal affinity
chromatography. The native proteins exhibited a high degree of oligomerisation
when analysed by size-exclusion chromatography. All three proteins were able
to protect malate dehydrogenase (MDH) from in vitro
thermal aggregation. They could also protect several soluble proteins in
E. coli extracts from thermal aggregation
in vitro, as well as protecting phycocyanin in extracts
from Synechococcus sp. PCC7942. None of the proteins
were able to protect photosystem II (measured as ΦPSII, the effective
quantum fluorescence yield of PSII) of thylakoids isolated from
Synechococcus sp. PCC7942 from heat damage
in vitro, although in vivo, after
acclimation, photosystem II did exhibit acquired thermotolerance.
Behaviour of abscisic acid and polyamines in antisense ACC oxidase melon (Cucumis melo) during ripening
Authors: Concepción Martínez-Madrid María , Flores Francisco , Romojaro Felix
Published: September 2002

The behaviour of transgenic antisense 1-aminocyclopropane-1-carboxylic acid oxidase melon (TAM) was studied during fruit ripening. Work focussed mainly on analysis of the evolution of other plant growth regulators like ABA and polyamines in this type of melon. Physical-chemical and physiological differences from untransformed melon (UTM) (Cucumis melo L. var. cantalupensis Naud. cv. V�drantais) began to appear from the time of the latter's ethylene crisis. Ethylene synthesis was inhibited by 97.7% in TAM at the time when UTM showed maximum ethylene levels. The ripeness index of TAM was lower, despite their higher soluble solids content, due to the higher titratable acidity. Unlike UTM, TAM rind maintained its colour and cell membrane integrity, although there was no difference in the pulp in this respect. Blocking ethylene biosynthesis affected the levels of ABA and the polyamine putrescine, the latter only in the rind. The possible relationship between ethylene, ABA and polyamines, the effect of blocking ethylene biosynthesis on the evolution of these regulators, and their role in fruit ripening are discussed.
Changes in phytohormone levels following inoculation of two soybean lines differing in nodulation
Authors: Bano Asghari , Harper James E. , Auge Robert M. , Neuman Dawn S.
Published: September 2002

Changes in the concentration of free and conjugated ABA, zeatin riboside (ZR), and IAA in response to Bradyrhizobium inoculation and subsequent nodulation were monitored in xylem sap, phloem sap, and leaves of soybean [Glycine max (L.) Merr. cv. Williams 82] and its hypernodulating mutant, NOD1-3. In this study, pre-inoculation concentrations of phloem and xylem sap ABA and ZR were lower in NOD1-3 than in Williams 82, a difference that was accentuated in phloem after inoculation. The concentration of xylem ABA increased within 6�h of inoculation, while the concentration of phloem and leaf ABA did not change until 48-96 h after inoculation. Leaf uptake of [3H]ABA and distribution to phloem sap was greater in Williams 82 than in NOD1-3 during 48-72�h after inoculation. Inoculation resulted in similar increases in phloem and leaf IAA concentrations in both cultivars. While inoculation increased xylem sap ZR in both lines, the concentration of ZR increased much earlier in NOD1-3. Of particular interest is that ratios between hormones were altered during nodulation. Leaf and phloem ABA/IAA ratios were higher in Williams 82 than in the hypernod mutant, while the phloem IAA/ZR was greater from inoculation until nodulation in the NOD1-3 hypernod mutant. The xylem ABA/ZR ratio, as well as phloem ABA/ZR ratio, decreased in Williams 82 following inoculation, and leaf ABA concentration was elevated. The most noteworthy results of this study, therefore, came from an examination of the ratios between hormones in xylem and phloem sap, and the demonstration that hormone transport may play an important role in autoregulation of root nodulation.
Effects of elevated CO2 and drought on chemical composition and decomposition of spring wheat (Triticum aestivum)
Authors: Liao JianXiong , Hou ZongDong , Wang GenXuan
Published: September 2002

The effects of elevated CO2 concentration and drought on the chemical composition and decomposition of spring wheat (Triticum aestivum L.) leaf litter were investigated. The results obtained were as follows: (i)�decomposition of leaf litter material grown under elevated CO2 and drought (ED) was significantly reduced (P=0.007), but no significant changes occurred under elevated CO2 (EW) (P=0.203) or drought (AD) (P=0.599). The loss of mass of leaf litter material decomposing under ambient CO2 (AW) was higher than that under AD and ED, but the difference between AW and EW was insignificant (P=0.318); (ii) compared with leaf litter material from plants grown under AW, ED litter had higher total C content, despite decreased soluble carbohydrates, and lower total N content, and hence increased C/N ratio; (iii) tannins and lignin were not significantly correlated with the loss of mass, but increased concentrations of lignin and tannins in the decomposing wheat material might reduce the rate of litter turnover in later stages of decomposition; (iv) the decreased decomposition rate at ED was the result of an increase in the C/N ratio, a decrease in total N content, and inhibition of soil microbial activity by drought. So there will be the need to increase external N inputs and decrease stalks to the spring wheat field to increase decomposition rates if CO2 concentration increases and semi-arid regions become drier in the future.