bluuebunny/crossref_metadata_2025 huggingface dataset:
Large sharks and plastic debris in KwaZulu-Natal, South Africa
Authors: Cliff Geremy , Dudley Sheldon F. J. , Ryan Peter G. , Singleton Neil
Published: September 2002

In total, 28 687 large sharks were caught between 1978 and 2000 in the nets
that protect users of the popular swimming beaches of KwaZulu-Natal, South
Africa, against shark attack. Over this 23-year period, 53 sharks
(0.18% of the catch) were found with polypropylene strapping bands
around the body. Less than 1% of the individuals from each of eight
species were entangled in this manner. The dusky shark
Carcharhinus obscurus was the most frequently entangled
species, with 27 individuals (0.47% of the species catch). There was an
increase in the incidence of entangled C. obscurus with
time. Those examined in the laboratory were significantly underweight.
Although entanglement may ultimately result in death, the low incidence
recorded in this study is unlikely to affect the populations of sharks
concerned. A total of 60 sharks (0.38% of those with recorded stomach
contents) had ingested plastic debris. The most common items were packets or
sheets. There was no increase in the ingestion of plastics with time. The
highest frequency of occurrence was in the tiger shark
Galeocerdo cuvier, with 38 individuals (7.5% of
tiger sharks examined).
A hypothesis to explain onshore records of long-nose lancetfish Alepisaurus ferox (Alepisauridae, Teleostei) in the North Pacific Ocean
Authors: Orlov Alexei M. , Ul'chenko Vasily A.
Published: September 2002

Long-nose lancetfish, Alepisaurus ferox, is a widely
distributed oceanic pelagic predator. It inhabits mainly tropical and
subtropical waters, where it spawns and the juveniles feed. Adults may feed
within the subarctic waters reaching as far north as Greenland, Iceland, and
the Bering Sea. Onshore records of lancetfish exist for the past 250 years.
Some authors suggested that lancetfish occurs onshore as a result of hunting.
Others thought that the species comes ashore during storms when the fish have
become weak as a result of repletion or pathologic invasion by parasites.
However, analysis of known onshore records of lancetfish in the North Pacific
Ocean shows that in most cases the fishes had empty stomachs, were not
infected with parasites, and were found during non-stormy periods. The dates
of most onshore lancetfish records in the North Pacific Ocean coincided with
periods of strong La Niña events. Hence, lancetfish mortality may be
related to sharp changes in oceanic conditions.
Fishery for the deep-water spiny lobster Palinurus delagoae in Mozambique, 1980 to 1999
Authors: de Sousa Barbara Palha
Published: September 2002

Catch and effort data collected from 1980 to 1999 from the commercial trap
fishery for Palinurus delagoae off Mozambique are
presented.Generalized linear models, using the variables year, month, area,
and depth, indicate a marked decline in catch rate with time.Intensive
exploitation has led to a rapid decline in catches (102 to 48 tonnes) and
catch rates (0.74 to 0.33 kg/trap haul) during the last five years. This
decline indicates that the population is sensitive to the high fishing levels
(over 200000 trap hauls), particularly since 1993. As these lobsters are
generally slow growing and long lived, recovery is expected to take a number
of years, provided that fishing stays relatively low. Studies of different
size categories show that juvenile catch rate was highest in deep water and
during summer after the moult in August to October, whereas the larger adult
size category was caught more in shallow water during spring, probably during
the mating aggregation. These catch rates reflect an inshore migration of
juveniles from deep to shallow water. The decline in catch rate appeared
greater amongst the small (juvenile) and medium lobsters because these more
abundant categories are more often the target of the fishery.
Simulations of coastal upwelling on the Sydney Continental Shelf
Authors: Marchesiello Patrick , Gibbs Mark T. , Middleton Jason H.
Published: September 2002

Two-dimensional numerical simulations of the response of the coastal waters of
Sydney, south-eastern Australia, to idealized upwelling-favourable winds are
presented. The spin up of the upwelling circulation is investigated, in
particular the structure of the nearshore circulation. The intensity of the
final upwelling state is found to be strongly linked to the activation of the
return flow through the bottom boundary layer, which is also related to the
strength of imposed alongshore pressure gradients. Results from a simulation
of upwelling forced by a deep-ocean alongshore-current jet also show the final
upwelling state to be weak in comparison with upwelling states produced by the
action of the local wind stress. Bottom boundary layer shut-down in the
presence of such a forcing jet is also discussed. A simulation of a real
upwelling event was also performed and good agreement was found between the
simulation and observations from a field experiment performed during summer
1994 in the Sydney coastal ocean.
Large-scale patterns in species richness and composition of temperate riverine fish communities, south-eastern Australia
Authors: Gehrke Peter C. , Harris John H.
Published: September 2002

Riverine fish in New South Wales were studied
to examine longitudinal trends in species richness and to identify fish
communities on a large spatial scale. Five replicate rivers of four types
(montane, slopes, regulated lowland and unregulated lowland) were selected
from North Coast, South Coast, Murray and Darling regions. Fishwere sampled
during summer and winter in two consecutive years with standardized gear that
maximized the range of species caught.
The composition of fish communities varied among regions and river types, with
little temporal variation. Distinct regional communities converged in montane
reaches and diverged downstream. The fish fauna can be classified into North
Coast, South Coast, Murray and Darling communities, with a distinct montane
community at high elevations irrespective of the drainage division. Species
richness increased downstream in both North Coast and South Coast regions by
both replacement and the addition of new species. In contrast, species
richness in the Darling and Murray regions reached a maximum in the slopes
reaches and then declined, reflecting a loss of species in lowland reaches.
The small number of species is typical of the freshwater fish faunas of
similar climatic regions world-wide. Fish communities identified in this study
form logical entities for fisheries management consistent with the
ecosystem-focused, catchment-based approach to river management and water
reform being adopted in Australia.
Endorheic versus karstic lakes: patterns of ostracod distributions and lake typology in a Mediterranean landscape (Castilla - La Mancha, Spain)
Authors: Roca J. R. , Mezquita F. , Rueda J. , Camacho A. , Miracle M. R.
Published: September 2002

In a survey for conservation of non-marine
aquatic systems, the ostracod compositions of 43 water bodies sampled in
central Spain were analysed by multivariate ordination (DCA) and
classification (TWINSPAN) methods, showing a clear division in lake typology.
The wide variety of life modes and habitat requirements of non-marine ostracod
species yields assemblages of species of value as ecological indicators.
Endorheic shallow lakes, highly temporary, are characterized by an assemblage
of circum-Mediterranean and endemic species. Karstic and more stable lakes are
inhabited by northern Holarctic or Palaearctic species, depending on the
history and environmental conditions of the water body. Between these two
extremes, the study of ostracod assemblages permits the distinction, on a
finer scale, of a gradient of lake types with different disturbance
conditions, resulting from a combination of hydrological, climatic, chemical
and anthropogenic factors. At the extreme of that gradient, highly tolerant
cosmopolitan species play an important role in the ostracod community of sites
severely affected by human activities.
Length and age compositions and growth rates of the Australian herring Arripis georgiana in different regions
Authors: Fairclough D. V. , Dimmlich W. F. , Potter I. C.
Published: September 2002

Arripis georgiana was collected from coastal waters in
Western Australia and South Australia. The opaque zones on the otoliths were
shown to be formed annually and thus their number could be used to age the
individuals of this species. Although the catches of
A. georgiana in south-western Australia, where spawning
occurs, were dominated by the 0+ to 5+ age classes, they did contain
females and males up to ten and nine years old, respectively. The von
Bertalanffy growth parameters for the two sexes in this region differed
significantly, with the asymptotic length
(L∞) being significantly
greater for females (262 mm) than for males (239 mm), whereas the reverse was
true for the growth coefficient (k), i.e. 0.813
v. 0.992. The catches of
A. georgiana eastwards of 121˚44′E on the
south coast of Western Australia, where spawning does not occur, were
dominated by the 0+ to 2+ age classes. The above data, when taken in
conjunction with earlier tagging experiments and the marked decline that
occurs in the number of 2+ fish in South Australia in summer, imply that,
during this period, many two-year-old individuals of
A. georgiana start migrating towards their spawning
areas in south-western Australia.
Effects of sewage effluent on the population structure of Brachidontes rostratus (Mytilidae) on a temperate intertidal rocky shore
Authors: Hindell Jeremy S. , Quinn G. P.
Published: September 2002

A single polluted site at Boags Rocks, south-eastern Australia, and four
control sites were used to evaluate the effect of secondary-treated sewage
effluent on the population structure, recruitment, growth and mortality of the
mussel Brachidontes rostratus. B. rostratus recruited in
greater numbers to mussel clumps at the outfall site than at control sites,
regardless of the origin of the mussel clumps. The effects of pollution on the
soft tissue mass and shell growth of juveniles depended on the origin of the
mussels; shell growth of mussels local to Boags Rocks was smaller than the
average shell growth recorded in mussels at the control sites, and individuals
transplanted into Boags Rocks had higher soft tissue mass than those at the
control sites. Mortality was greater at the polluted site than the control
sites, regardless of mussel origin. Changes in the population structure of
B. rostratus as a result of the discharge of sewage
effluent have implications for intertidal fauna that use the habitat created
within mussel clumps.
Consistent timing of juvenile fish recruitment to seagrass beds within two Sydney estuaries
Authors: Smith Kimberley A. , Suthers Iain M.
Published: September 2002

Recruitment patterns of juvenile
Rhabdosargus sarba (Sparidae) and
Pelates sexlineatus (Terapontidae) were examined by
frequent (1–4 weeks) beach seining of seagrass beds in Sydney,
south-east Australia. Two sites within each of two estuaries (Botany Bay and
Pitt Water) were sampled for one year. One site within Botany Bay was sampled
for 3 years. A total of 12 824 juveniles of R. sarba and
7037 juveniles of P. sexlineatus were collected.
R. sarba recruited in 4 pulses during winter/spring,
while P. sexlineatus recruited in 6 pulses during
summer/autumn, and the timing of recruitment events was consistent among
locations and years. P. sexlineatus recruitment
coincided with new moons, but R. sarba recruitment dates
were less precisely determined. Predictable annual recruitment patterns result
in temporal partitioning of seagrass habitat between these two abundant
estuarine species. Spatial differences in magnitude of recruitment events
among sites reflected patterns of estuarine circulation.
Larval distribution and abundance of blue and spotted warehous (Seriolella brama and S. punctata: Centrolophidae) in south-eastern Australia
Authors: Bruce B. D. , Neira F. J. , Bradford R. W.
Published: September 2002

The early life histories of the commercially important blue and spotted
warehous (Seriolella brama and
S. punctata) were examined on the basis of archived
ichthyoplankton samples collected over broad areas of southern Australia.
Larvae of both species were widely distributed during winter and spring within
shelf and slope waters. Larvae of S. brama were recorded
from Kangaroo Island, South Australia (SA), to southern New South Wales (NSW).
Seriolella punctata larvae were recorded from western
Tasmania to southern NSW. Back-calculated spawning dates, based on otolith
microstructure, indicated that spawning predominantly occurs during late July
and August but that the timing of spawning varies between regions. The
abundances of small larvae (<5. 0 mm body length) were highest for both
species off western Tasmania and southern NSW. No small
S. brama larvae were recorded between southern Tasmania
and southern NSW, whereas low but consistent numbers of small
S. punctata larvae were found between these regions. The
data suggest that there are separate spawning areas for
S. brama in western and eastern regions of
Australia’s South East Fishery. The pattern for
S. punctata is less clear, but suggests a more
continuous link among populations in south-eastern Australia.
Reproductive biology, early life-history and settlement distribution of sand flathead (Platycephalus bassensis) in Tasmania
Authors: Jordan Alan R.
Published: September 2002

The life-history ecology of P. bassensis was examined to
determine the spatial and temporal patterns of spawning, larval transport and
settlement distribution in coastal and continental shelf waters of southern
and eastern Tasmania. Larval development is characterized by a large size at
flexion and pelvic and dorsal fin formation, lightly pigmented trunk and tail
and the absence of strong teeth on the roof of the mouth or lower jaw. The
distribution of spawning fish and larvae and patterns of hydrography indicate
that spawning occurs throughout estuaries, coastal embayments and inshore
shelf waters of southern and eastern Tasmania. Larvae are concentrated in mid
waters, which retain larvae inshore because cross-shelf subsurface currents
are predominantly onshore. Spawning in P. bassensis
occurred for up to six months between October and March. The broad range of
lengths of 0+ fish in every month indicates that settlement occurred over
an extended period, reflecting the protracted spawning period. Juveniles
showed a preference for unvegetated habitats in nearshore waters, compared
with beds of the seagrass Heterozostera tasmanica. Size
compositions of 0+ fish indicate the presence of several cohorts in most
months;this is discussed in terms of early life-history strategy and
availability of settlement habitats.
Genetic population structure of species in the South East Fishery of Australia
Authors: Ward R. D. , Elliott N. G.
Published: September 2002

A summary is given of allozyme, mitochondrial DNA and microsatellite data for
commercially important species (13 fish and 7 shellfish) in Australia’s
South East Fishery, including contiguous waters and the Tasman Sea. For most
fish species, genetic population differentiation was limited and in about half
the studies was non-detectable. Striking population differentiation was
recorded for gemfish. For fish species, on average only 2–3% of
the total genetic variation could be attributed to population differentiation
within southern Australian waters. In shellfish, ~5% of variation arose
from population differences. The reduced differentiation of fish populations
may be due to a longer larval period and greater adult mobility. Although
there was evidence that the Tasman Sea acts as a barrier to gene flow, with
most fish species showing significant differences between Australia and New
Zealand, the degree of differentiation was small (only ~2%). The
limited genetic differentiation obserred for most species is attributable to
the lack of major oceanographic and environmental barriers to gene flow,
together with influential current systems; it necessitates large sample sizes
for good genetic tests. However, significant genetic stock structuring is
apparent for several fish and shellfish species – particularly for
coastal species, where isolation by distance may explain some of the data. Any
evidence for genetic stock structure must be factored into plans for
sustainable management.
Expression of a UDPglucose pyrophosphorylase cDNA during fruit ripening of banana (Musa acuminata)
Authors: Pua Eng-Chong , Lim Stevenson Szu-Wei , Liu Pei , Liu Jian-Zhong
Published: September 2002

We report the isolation of a banana cDNA, designated MWUGPA, encoding uridine
diphosphoryl (UDP)-glucose pyrophosphorylase (UGPase, EC.2.7.7.9) that
catalyses the reversible conversion between glucose 1-phosphate and UDPglucose
in plants and animals. Furthermore, UGPase expression in fruit during ripening
and in response to exogenous ethylene and sugars was also investigated. MWUGPA
encodes a polypeptide of 467 amino acid residues and shares a high degree of
sequence similarity (85–90%) with other plant UGPase homologs. In
northern blot analysis, a 1.7-kb UGPase transcript was detected in both the
vegetative and reproductive organs, but the former was considerably less
abundant than the latter. In fruit, the level of accumulated transcripts was
higher in pulp than peel at all ripening stages. Transcript abundance in both
fruit tissues was relatively constant during ripen-ing, but pulp transcripts
surged in the ‘more green than yellow’ category fruit when
ethylene also increased. Further analysis revealed that UGPase expression in
fruit was ethylene-inducible, but the response was tissue-specific, as
evidenced by the promoting effect of exogenous ethylene on accumulation of
UGPase transcripts in pulp but not peel. Exogenous application of sucrose and
fructose also increased UGPase transcript abundance in leaf and fruit tissues,
especially pulp, whereas exogenous glucose had little or no effect. The
results of this study indicate that ethy-lene and soluble sugars may play a
regulatory role in UGPase expression during ripening in banana fruit.
Activities of the cyanide-resistant respiratory pathway in leaves of sun and shade species
Authors: Noguchi Ko , Go Chun-Sim , Terashima Ichiro , Ueda Shingo , Yoshinari Tadashi
Published: September 2002

Higher plant mitochondria have a cyanide-resistant alternative respiratory
pathway of electron transport (AP) that is not coupled to proton
translocation. To characterise the ecophysiology of this apparently
‘wasteful’ pathway, we constructed a system consisting of a
gas-phase oxygen electrode and an air sampling line for measurement of stable
oxygen isotope ratios. With this system, we were able to measure respiratory
rates of a small amount of leaf segments of ca 0.6 g
fresh weight, and collect about 100 L of the air from the oxygen electrode
chamber several times. The 18
O/16 O ratio in the air samples was measured by mass
spectrometry. The activity of AP was estimated based on the isotopic
discrimination of 18 O. We used the leaves of
Alocasia odora (Lodd.) Spach., a shade species, and
Spinacia oleracea L. and
Phaseolus vulgaris L., sun species. These plants were
grown at two levels of photosynthetically active photon flux density (PPFD).
Three main findings were: (1) in the leaves of A. odora,
the contribution of AP was less than 10% of the total respiratory rate,
irrespective of growth PPFD; (2) for the sun species grown at high PPFD, the
contribution of AP in the leaves was about 40% early in the night, but
decreased dramatically late in the night; and (3) when
S. oleracea was grown at low PPFD, the contribution of
AP in the leaves declined. The low activity of AP in the leaves of
A. odora suggests that the efficiency of adenosine
triphosphate (ATP) production (ATP/O 2 ) of this
species is high. This may be especially important in shaded environments where
input of light energy is low. We also suggest that, in the leaves of sun
species, ATP/O 2 changes depending on the
conditions.
A two-pinhole technique to determine distribution profiles of relative elemental growth rates in the growth zone of grass leaves
Authors: Schmidhalter Urs , Hu Yuncai
Published: September 2002

A new modified pricking technique, a two-pinhole method, was designed to
determine the spatial distribution of leaf elongation of grasses. This new
technique makes it possible to obtain the distribution profiles of relative
elemental growth rates in the growth zone, to evaluate the effect of pricking
on the distribution profile of leaf elongation in the growth zone and to
decrease the reduction in the elongation rate of grass leaves due to pricking.
The acute effect of copper on the levels of indole-3-acetic acid and lignin in peanut roots
Authors: Li Tsai-Chi , Feng Teng-Yung , Chen Wen-Shaw , Liu Zin-Huang
Published: September 2002

Cu-treated peanut (Arachis hypogaea L.) seedlings showeda significant inhibition in peanut root growth, and a decrease in endogenousindole-3-acetic acid (IAA) content. The decline of IAA content in Cu-treatedtissue was accompanied by an increase in the activity of cationic peroxidase(POD) isozyme P8.5, which was correlated with an increase in cationic PODtranscripts. Cu might suppress the growth of peanut roots by inducing thesynthesis of the cationic POD isozyme that degrades endogenous IAA. Theincrease in the activity of anionic POD isozyme P3.5 was correlated with therise in lignin content in Cu-treated roots. We suggest that the increase inanionic POD isozyme P3.5 induced by Cu might be responsible for ligninsynthesis in peanut roots, and may also remove excess hydrogen peroxide causedby Cu, thus playing a detoxifying role during Cu treatment.
Isolation of an ent-kaurene oxidase cDNA from Cucurbita maxima
Authors: Helliwell Chris A. , Olive Mark R. , Forster Leigh Gebbie Richard , Peacock W. James , Dennis Elizabeth S.
Published: September 2002

Four distinct cDNAs isolated from developing
Cucurbita maxima Duchesne seeds included CYP701A1, a
member of the same subfamily of cytochrome P450 enzyme as the
Arabidopsis ent-kaurene oxidase GA3 which catalyses an
early step in gibberellin (GA) biosynthesis. We have shown by complementation
of the Arabidopsis ga3-2 mutant that the CYP701A1 cDNA
encodes an ent-kaurene oxidase activity. Another cDNA,
CYP88A2, encodes a protein which is in the same subfamily as the maize Dwarf3
protein and is likely to encode another GA biosynthetic enzyme catalysing a
reaction between ent-kaurenoic acid and
GA12.
Antisense suppression of the lignin biosynthetic enzyme, caffeate O-methyltransferase, improves in vitro digestibility of the tropical pasture legume, Stylosanthes humilis
Authors: Rae Anne L. , Manners John M. , Jones Raymond J. , McIntyre C. Lynne , Lu De-Yang
Published: September 2002

The high lignin content of tropical forage plants reduces digestibility and
voluntary feed intake by ruminants. We have used antisense technology to
suppress caffeate O-methyltransferase (COMT EC,
2.1.1.68), a lignin biosynthetic enzyme in the tropical forage legume,
Stylosanthes humilis Kunth. Plants were transformed
using a Ti binary vector containing an antisense COMT construct under the
control of the CaMV 35S promoter. From 50 transgenic plants, five were
selected on the basis of normal morphology, high levels of antisense gene
expression and altered lignin histochemistry. No plants with altered lignin
were observed in a population of 20 transgenic plants derived using a binary
vector that lacked the COMT cDNA insert. The progeny of lignin-altered plants
were analysed for COMT enzyme activity and lignin histochemistry. A variety of
COMT and lignin phenotypes was observed. In several T1
plants, COMT activity was specifically suppressed by more than 95%
compared to controls. In these plants, expression of antisense mRNA was high
while sense mRNA could not be detected on northern blots. The overall lignin
content of these plants was unchanged but histochemical tests showed
abnormally low levels of the syringyl component, mimicking the pattern of
young tissue. Digestibility of these transgenic plants was assessed by
incubation of stem material with rumen fluid and acid pepsin
in vitro. The digestibility of the antisense material
was increased dramatically compared to that of equivalent samples from control
transformed plants (72 vs 62%).
Effects of growth substances on the protoplasmic drought tolerance of leaf cells of the resurrection grass, Sporobolus stapfianus
Authors: Ghasempour Hamid R. , Anderson Esther M. , Gaff Donald F.
Published: September 2002

Hydrated leaves of the resurrection grass
Sporobolus stapfianus Gandoger are not desiccation
tolerant, but moderate to severe drought stress can induce their desiccation
tolerance while the leaves remain attached to drying intact plants. Free-cell
suspensions prepared from fully turgid leaves of
S. stapfianus were also found to be
desiccation-sensitive. In this study a sensitive assay was developed to
determine the effect of exogenous substances on the protoplasmic drought
tolerance (PDT) of cell suspensions. Suspended cells were incubated with a
wide variety of individual plant growth substances over a range of
concentrations. After the incubation, the protoplasmic drought tolerance at
each concentration of each substance was determined osmotically. Brassinolide
(BR) and methyljasmonic acid (MJA), applied separately, gave the greatest
effect — each improved PDT by approximately 6 MPa, compared with
controls incubated without growth substances. Exogenous abscisic acid (ABA)
improved the PDT of S. stapfianus only slightly (about 1
MPa). Salicylic acid (SA), 1-aminocyclopropane–1-carboxylic acid (ACC),
ethephon, gibberellic acid (GA), kinetin (KN) andN
6 -(2-isopentyl)adenine (2ip) each improved PDT by
ca 1.5 MPa. Indoleacetic acid (IAA) had no effect, and
zeatin (ZN) had a deleterious effect on PDT.
Incubation of suspended cells in combinations of two growth substances (MJA
with ABA, ACC, BR, GA, IAA or KN; BR with ABA) produced no evidence of
synergism, or in most cases, even of additive effects of the tested
substances. ABA, BR and MJA (applied separately) stimulated the synthesis of
numerous specific proteins. Each growth substance stimulated the synthesis of
differing proteins, with four exceptions. This investigation raises the
possibility that BR and MJA may play a role in a chain of events which leads
eventually to the induction of desiccation tolerance in leaves of
S. stapfianus. The effects on cell PDT observed in this
study, while large, were insufficient to account for the remarkable
improvement observed in the PDT of S. stapfianus leaves
attached to drying plants.
GmNiR-1, a soybean nitrite reductase gene that is regulated by nitrate and light
Authors: Kim Chang-Hoon , Jun Sung-Soo , Hong Young-Nam
Published: September 2002

A genomic DNA clone encoding nitrite reductase (NiR; EC 1.7.7.1),
GmNiR-1, was isolated from soybean
[Glycine max (L.) Merr.]. It is composed of
four exons and three introns carrying an open reading frame coding for a
protein of 596 amino acids. The putative MW of GmNiR-1
is 67 kDa with theoretical pI of 6.95, but the measured MW is ca 64 kDa. The
difference between putative and measured MW of GmNiR-1
lies in the presence of a transit peptide. Genomic DNA blot analysis suggested
that soybean NiR gene family consisted of at least three genes. In 2-week-old
plants grown in the nitrate-supplemented soil, GmNiR-1
was expressed in roots and leaves, but not in hypocotyls. Transcript level of
GmNiR-1 in roots was not increased by light, but was
increased by nitrate even in the dark. However, light and nitrate had a
synergistic effect on the increased expression of
GmNiR-1. A polyclonal antibody generated against the
C-terminal of GmNiR-1 hybridized to a single (62 kDa),
double (62 and 64 kDa), and three bands (62, 64 and 66 kDa) in roots,
hypocotyls and leaves, respectively. In etiolated seedlings, NiR proteins in
roots and hypocotyls were induced by simultaneous treatment with light and
nitrate, but those in cotyledons were already present substantially without
induction, implying the presence of at least two kinds of
NiR genes (a constitutive one and an inducible one
regulated by light and nitrate) in soybean seedlings.
Role of membrane transport in phloem translocation of assimilates and water
Authors: Patrick John W. , Zhang Wenhao , Tyerman Stephen D. , Offler Christina E. , Walker N. Alan
Published: September 2002

Most growth and storage organs (sinks) of higher plants import assimilates in
solution by bulk flow through the phloem, driven by differences in hydrostatic
pressure. These differences in pressure, located between the ends of the
interconnecting phloem path, are generated by osmotic water movement, driven
in turn by membrane transport of solutes. Sucrose, amino-nitrogen compounds
and potassium represent the osmotically important solutes found in phloem
contents of most species. Phloem loading and unloading events of these
assimilate species play central roles in determining phloem translocation
rates and partitioning of assimilates and water. Depending on plant species,
leaf vein order and sink type, phloem loading and unloading may follow
apoplasmic or symplasmic routes. Irrespective of the cellular pathway
followed, assimilates are transported across plasma and organellar membranes.
Aquaporins, amino-nitrogen transporters, sucrose transporters and potassium
channels have been detected in key sites along the
source–phloem–sink transport pathway. Reverse genetics has
demonstrated that sucrose/proton symporters are important in transport
events necessary for phloem loading in Solanaceousplant
species. Drawing on circumstantial evidence, we review possible functions the
remaining membrane transporters and channels may serve in driving phloem
translocation of assimilates and water from source to sink.
Problems and prospects of cyanobacterial biofertilizer for rice cultivation
Authors: Hashem Md. Abul
Published: September 2002

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000
Nitrogen (N2)-fixing cyanobacteria are a dominant
microflora in rice fields and are currently being used sporadically as a
supplement to chemical nitrogen fertilizers for rice cultivation in
rice-growing countries, including India and Bangladesh. This technology
suffers from serious drawbacks and its use at the farm level is not gaining
universal acceptance due to some major problems, which include development of
a suitable production technology of biofertilizer for field use, establishment
of the applied biofertilizer in the rice field and the sustainability of the
technology. In order to significantly improve the efficient use of
cyanobacteria as a N-based biofertilizer for rice cultivation, experiments
were carried out in different dimensions both in the laboratory and field.
Cyanobacterial strains were isolated, identified and quantified from a wide
range of distinctively different types of soils, viz. acid, calcareous,
saline, red and neutral soils under different agro-ecological zones (AEZ) of
Bangladesh. The isolated strains were tested for their
N2-fixing capacity and growth rate under various stress
conditions prevailing in the rice field e.g. pH, combined N, pesticides,
salinity and nutrient availability in order to select suitable strains for use
as biofertilizer. Large-scale cyanobacterial biofertilizer was produced with
the strains showing high rates of growth and N2 fixation
both in liquid cultures under laboratory conditions and in soils of their
habitats and non-habitats under open air. To assess the effectiveness of the
produced biofertilizer, field trials at the selected locations were carried
out on rice. Results of the field trials showed that cyanobacterial
biofertilizer may reclaim the problem soils such as acid soils and saline
soils, improve the fertility status and may supplement 25–35% N
for rice cultivation in these soils. This biofertilizer may be used in
improving the soil environment.
Plant water use efficiency of 17 Australian NAD-ME and NADP-ME C4 grasses at ambient and elevated CO2 partial pressure
Authors: Ghannoum Oula , von Caemmerer Susanne , Conroy Jann P.
Published: September 2002

This study investigates the response to elevated CO2
partial pressure (pCO2) of
C4grasses belonging to different biochemical subtypes
(NAD–ME and NADP–ME), and taxonomic groups (main Chloroid
assemblage, Paniceae and Andropogoneae). Seventeen C4
grasses were grown under well-watered conditions in two glasshouses maintained
at an average dailyppCO2 of 42
(ambient) or 68 (elevated) Pa. Elevated
pCO2 significantly increased plant
water-use efficiency (WUE; dry matter gain per unit water transpired) in 12
out of the 17 C4 grasses, by an average of 33%.
In contrast, only five species showed a significant growth stimulation. When
all species are considered, the average plant dry mass enhancement at elevated
pCO2 was 26%. There were no
significant subtype (or taxa) ×
pCO2 interactions on either WUE or
biomass accumulation. When leaf gas exchange was compared at growth
pCO2 but similar light and
temperature, high pCO2-grown
plants had similar CO2 assimilation rates
(A) but a 40% lower stomatal conductance than
their low pCO2-grown counterparts.
There were no signs of either photosynthetic or stomatal acclimation in any of
the measured species. We conclude that elevated
pCO2 improved WUE primarily by
reducing stomatal conductance.
Can plants manipulate bacterial quorum sensing?
Authors: Bauer Wolfgang D. , Teplitski Max
Published: September 2002

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000
Higher plants have been found to secrete a variety of unknown signal-mimic
compounds that can stimulate or inhibit behaviors in bacteria, which are
regulated by N-acyl homoserine lactone (AHL) signal
molecules. A wide range of bacterial species use AHLs or other signal
molecules to regulate the expression of many of their genes in response to
changes in population density. Thus, the ability of higher plants to
specifically alter AHL-regulated behavior in bacteria by production of AHL
signal-mimic compounds could be of broad consequence. We briefly review what
is known about AHL signaling in bacteria and the synthesis of AHL signal-mimic
compounds by plants, and then consider some of the important questions
concerning the roles these plant signal-mimic compounds may play in natural
encounters between plants and bacteria.
Responses of agronomically important crops to inoculation with Azospirillum
Authors: Dobbelaere Sofie , Croonenborghs Anja , Thys Amber , Ptacek David , Vanderleyden Jos , Dutto Pablo , Labandera-Gonzalez Carlos , Caballero-Mellado Jesus , Aguirre Juan Francisco , Kapulnik Yoram , Brener Shimon , Burdman Saul , Kadouri Daniel , Sarig Shlomo , Okon Yaacov
Published: September 2002

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000
Azospirilla are free-living rhizobacteria that are able to promote plant
growth and increase yields in many crops of agronomic importance. It is
assumed that the bacteria affect plant growth mainly by the production of
plant growth promoting substances, which leads to an improvement in root
development and an increase in the rate of water and mineral uptake. In the
present review, we discuss the physiological responses of the plant roots to
inoculation with Azospirillum, and report on field and
greenhouse experiments carried out with these bacteria during 1994–2001
in Belgium, Uruguay, Mexico and Israel.
Xanthophyll cycle, light energy dissipation and photosystem II down-regulation in senescent leaves of wheat plants grown in the field
Authors: Lu Congming , Lu Qingtao , Zhang Jianhua , Zhang Qide , Kuang Tingyun
Published: September 2002

Photosynthesis, the xanthophyll cycle, light energy dissipation and
down-regulation of photosystem II (PSII) in senescent leaves of wheat plants
grown in the field were investigated. With the progress of senescence, maximal
efficiency of PSII photochemistry decreased only slightly early in the morning
but substantially at midday. Actual PSII efficiency, photochemical quenching,
efficiency of excitation capture by open PSII centres, and the I–P phase
of fluorescence induction curves decreased significantly and such decreases
were much more evident at midday than in the morning. At the same time,
non-photochemical quenching, thermal dissipation and de-epoxidation status of
the xanthophyll cycle increased, with much greater increases at midday than in
the morning. These results suggest that the xanthophyll cycle played a role in
photoprotection of PSII in senescent leaves by dissipating excess excitation
energy. Taking into account the substantial decrease in photosynthetic
capacity in senescent leaves, our data seem to support the view that the
decrease in actual PSII efficiency in senescent leaves may represent a
mechanism to down-regulate photosynthetic electron transport to match the
decreased CO2 assimilation capacity and avoid
photodamage of PSII from excess excitation energy.
Lack of downregulation of photosynthesis in a tropical root crop, cassava, grown under an elevated CO2 concentration
Authors: Fernández María Dolores , Tezara Wilmer , Rengifo Elizabeth , Herrera Ana
Published: September 2002

We evaluated the effects of an elevated [CO2] on photosynthesis and growth of cassava plants grown in open-top chambers with an adequate supply of water and N and a sufficient rooting volume. Cassava plants (Manihot esculenta Crantz. cv. Motilona) showed higher photosynthetic rates (Pn) when grown and measured at elevated [CO2] (680 µmol mol-1) than when grown and measured at ambient [CO2] (480 µmol mol-1). No downregulation of photosynthesis due to elevated [CO2] was found, since carboxylation efficiency increased after 220 d in spite of a decrease in leaf soluble protein, Rubisco, and leaf N content. Soluble sugar and starch contents decreased with time under elevated [CO2], the decrease in starch content coinciding with the beginning of the increase in root mass. Canopy Pn by leaf area decreased with time under elevated [CO2] but, when canopy Pn was expressed by ground area, higher and constant rates were observed, suggesting a higher productivity in plants grown at elevated [CO2]. The absence of differences between growth [CO2] in root : shoot ratio observed suggests that elevated [CO2], while causing increases in the shoot as well as the root, did not affect the pattern of biomass allocation. Acclimation responses of gas exchange parameters changed during the experiment. The absence of downregulation of photosynthesis was associated with a decrease in leaf sugar and starch contents of plants grown at elevated [CO2], which suggests a favourable source/sink relationship.
A possible role for carbonic anhydrase in the lumen of chloroplast thylakoids in green algae
Authors: van Hunnik Eddy , Sültemeyer Dieter
Published: September 2002

In order to understand the function of the lumen carbonic anhydrase (CA) which
is bound to PSII at the lumenal side of the thylakoids in chloroplasts of
eukaryotic algae, thylakoids were isolated from chloroplasts of
Tetraedron minimum,
Chlamydomonas noctigama, the cell wall-less mutant
Chlamydomonas reinhardtii CW15, and a
C. reinhardtii CW15/CIA3 mutant which lacks the
lumen CA. The isolated thylakoids produced O2 on
illumination and exhibited electron flow between PSII and PSI, indicating that
the thylakoids were intact and the photosynthetic apparatus were functional.
We could not detect any uptake of
HCO3–,nor efflux of
CO2, from the thylakoids upon illumination, making it
improbable that the CA present in the lumen of the thylakoids would play a
role in furnishing CO2 for Rubisco. We were able to
determine ATP production upon illumination in isolated thylakoids. Under high
inorganic carbon (Ci; 5 mM), all species showed significant amounts of ATP
being produced. Under low Ci (200 M), we could not detect ATP formation from
C. reinhardtii CW15/CIA3 upon illumination. This
mutant was not able to survive more then 4 h of low Ci in culture. We
therefore suggest that the lumen CA is not involved in the
CO2 concentrating mechanism, but might play a role in
the formation of a proton gradient across the thylakoid membranes.
Flexibility of nitrogen metabolism in the tropical C3crassulacean acid metabolism tree species Clusia minor
Authors: Arndt Stefan K. , Wanek Wolfgang , Hoch Günter , Richter Andreas , Popp Marianne
Published: September 2002

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001.
The C3-crassulacean acid metabolism tropical hemiepiphytic tree, Clusia minor L., is highly flexible in terms of ecological sites occupied, life forms, and photosynthetic and metabolic pathways. We studied nitrogen uptake patterns in two glasshouse 15N-labelling experiments using hydroponically-grown plants and excised roots of pot-grown C. minor, and investigated leaf and root nitrate reductase activity (NRA) in a field study in Venezuela. The results of both 15N-uptake experiments indicate that C. minor utilized all offered nitrogen sources, but clearly preferred to take up NH4+ over glycine (GLY) and NO3-. The uptake pattern of NH4+ and NO3- was identical in intact plants and excised roots, and NH4+ was taken up to a much larger extent in both experiments. Gas chromatography-mass spectrometry (GC-MS) analysis of amino acids in excised roots revealed that glutamine (45 atom-%), glutamate (23 atom-%) and alanine (34 atom-%) accounted for most of the labelled soluble amino acids after 2-h labelling with 15NH4+. High amounts of 15N in GLY and serine confirmed that GLY was taken up as an intact molecule and metabolized in the excised roots. With 15NO3- labelling, only a small amount of 15N was found in the amino acid fraction, indicating a low NO3- assimilation rate by nitrate reductase. This was confirmed by low NRA of leaves and roots in C. minor plants in Venezuela. It appears, therefore, that a high degree of plasticity is not reflected in nitrogen uptake and metabolism. Although C. minor exhibits clear preferences for NH4+ uptake, it can utilize other sources of nitrogen, and the nitrogen uptake pattern represents an adaptation to the natural environments in which C. minor can grow.
Probing the circadian control of phosphoenolpyruvate carboxylase kinase expression in Kalanchoë fedtschenkoi
Authors: Hartwell James , Nimmo Gillian A. , Wilkins Malcolm B. , Jenkins Gareth I. , Nimmo Hugh G.
Published: September 2002

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001.
In crassulacean acid metabolism (CAM) plants, phosphoenolpyruvate carboxylase (PEPC) kinase is expressed at night under the control of a circadian oscillator. We have proposed that this is an indirect effect, secondary to circadian fluctuations in the level of a metabolite, possibly cytosolic malate, resulting from a primary effect on the permeability of the tonoplast (Nimmo 2000, Trends in Plant Science 5, 75-80). Here we show that the nocturnal accumulation of PEPC kinase translatable mRNA and phosphorylation of PEPC in Kalanchoë fedtschenkoi is blocked by the protein phosphatase inhibitor cantharidin. This implicates protein dephosphorylation in the circadian pathway that regulates expression of PEPC kinase. We also show that the effect of reducing the temperature from 30 to 15 °C on CO2 fixation by detached leaves held in constant darkness and normal air is 'gated' by the circadian clock. This strongly supports the view that the effect of the clock on the expression of PEPC kinase is secondary rather than direct. We have developed a non-aqueous fractionation protocol that separates the cytosolic material in mature leaves from vacuolar material. The cytosolic malate in mature leaves represents a very small part of the total malate, and its concentration cannot be measured precisely by this method.
Short-term plasticity of crassulacean acid metabolism expression in the epiphytic bromeliad Tillandsia usneoides
Authors: Haslam Richard , Borland Anne , Griffiths Howard
Published: September 2002

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001.
The regulation and flexibility of the crassulacean acid metabolism (CAM) pathway has been investigated in the 'extreme epiphyte' Tillandsia usneoides (L.). Submerging strands of T. usneoides under water, thereby inhibiting the supply of atmospheric CO2, allowed non-invasive in vivo manipulation of the supply of CO2 during the nocturnal Phase I of CAM. Once the plants were removed from submersion, T. usneoides maintained open stomata, and net CO2 uptake occurred throughout most of the photoperiod. Variability in the expression of CAM allowed T. usneoides to compensate for restricted CO2 availability through Phase I of CAM by adjusting gas exchange rates through the photoperiod and subsequent dark period to maintain a constant internal supply of CO2 in the light. Furthermore, T. usneoides demonstrated a gradual, rather than rapid, change in phosphoenolpyruvate carboxylase (PEPC) activation across the day-night cycle, such that PEPC and Rubisco appear to work in tandem in order to maintain carbon balance for this extreme atmospheric bromeliad.
Modes of active inorganic carbon uptake in the cyanobacterium, Synechococcus sp. PCC7942
Authors: Price G. Dean , Maeda Shin-ichi , Omata Tatsuo , Badger Murray R.
Published: September 2002

Cyanobacteria (blue–green algae) have evolved a remarkable environmental
adaptation for survival at limiting CO2 concentrations.
The adaptation is known as a CO2 concentrating
mechanism, and functions to actively transport and accumulate inorganic carbon
(Ci; HCO3– and
CO2) within the cell. Thereafter, this Ci pool is
utilised to provide elevated CO2 concentrations around
the primary CO2 fixing enzyme, Rubisco, which is
encapsulated in a unique micro-compartment known as the carboxysome. Recently,
significant progress has been gained in understanding the different types of
Ci transport in cyanobacteria. This semi-review centres on the model
cyanobacterium, Synechococcus sp. PCC7942, which
possesses at least four distinct modes of Ci uptake when grown under Ci
limitation, each possessing a high degree of functional redundancy. The four
modes so far identified are: (i) BCT1, an inducible, high affinity
HCO3– transporter of the bacterial
ATP binding cassette transporter family, encoded
by cmpABCD; (ii) a constitutive,
Na+-dependent
HCO3– transport system that can be
allosterically activated (possibly by phosphorylation) in as little as 10 min;
(iii) and (iv) two CO2 uptake systems, one constitutive
and the other inducible, based on specialised forms of thylakoid-based, type
1, NAD(P)H dehydrogenase complexes (NDH-1). Here, we forward a speculative
model that proposes that two unique proteins, ChpX and ChpY, possess
CO2 hydration activity in the light, and when coupled to
photosynthetic electron transport through the two specialised NDH-1 complexes,
result in net hydration of CO2 to
HCO3– as a crucial component of
the CO2 uptake process.