bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of nitrogen and potassium on the yield and quality of irrigated Brussels sprouts (Brassica oleracea L. var. gemmifera) cvv. Roger and Oliver grown in South Australia
Authors: Williams CMJ , Maier NA , Potter MJ , Collins GG
Published: March 2005

This study was conducted to assess the effects of nitrogen (N) and potassium (K) on the yield and size distribution of Brussels sprouts (Brassica oleracea L. var. gemmifera) grown with sprinkler irrigation in the Mt Lofty Ranges, South Australia. The cultivars grown were Oliver and Roger which are early and mid season types, respectively. Yields of swollen axillary buds or Brussels sprouts were assessed over 4-7 harvests. Five rates of N (0, 125, 250, 375, 600 kg/ha) with 3 rates of K (0, 150, 300 kg/ha) were applied over 8 side-dressings during the 7-8-month cropping period in randomised block experiments. Four experiments were conducted during 1992-93 (sites 1 and 2) and 1993-94 (sites 3 and 4) on silty loam, loam and sandy loam soils. The effect of N and K on sprout colour was determined at sites 3 and 4. Thiocyanate concentrations in sprouts and the bitterness of sprouts, from the nil and highest K treatment, and from plants in the crop adjacent to the experimental area, were determined for sites 1 and 2. In 3 of the 4 experiments, applied N significantly (P<0.001) increased total yield of sprouts harvested. Yield increases due to applied N ranged from 51 to 78%. At site 1 (cv. Oliver), there was no yield response to applied N but at sites 2 and 4 (cv. Roger) and site 3 (cv. Oliver), 319, 377 and 383 kg N/ha, respectively were required for 95% maximum yield. At responsive sites, application of N significantly increased both yield of sprouts at all harvests except harvest 1, and yield of 20-<30 and 30-<40 g sprouts, which are the preferred size ranges. Increasing rates of N significantly (P<0.05) increased yield of 240 g or large sprouts at all 3 responsive sites. The effect of applied N on sprout colour was inconsistent. At site 4, application of N significantly (P<0.001) increased the mean colour rating of sprouts, in contrast, at site 3 the effect was not significant (P>0.05). At both sites, mean colour ratings decreased during the harvest period irrespective of N applied. Total yield, size and colour of sprouts were not significantly (P>0.05) affected by rate of applied K at any site. It was concluded that extractable K concentrations of 140-260 mg/kg in the surface (0-15 cm) soils were adequate and not limiting yield. At site 1, thiocyanate concentration in sprouts and sprout bitterness increased significantly (P<0.001) when the highest rate of K2SO4 was applied. At site 2, which had received higher rates of sulfate-based fertilisers in previous years, the effect was not significant (P>0.05). This finding suggests that application of high rates of K2SO4 to Brussels sprouts should be avoided to ensure bitterness does not adversely affect the marketability of sprouts.
Mineral nutrition of cassava (Manihot esculenta Crantz) grown in replaced soil after bauxite mining at Weipa, Queensland
Authors: Fulton MC , Bell LC , Asher CJ
Published: March 2005

The yield potential of cassava with optimal mineral nutrition was evaluated in a lateritic red earth that was replaced after bauxite mining at Weipa, Queensland. There were 9 field experiments. In 8 separate experiments, 5 rates each of nitrogen (N), potassium (K), magnesium (Mg), sulfur, copper, zinc (Zn), boron or molybdenum fertilisers were banded into the soil. In the phosphorus (P) experiment, triple superphosphate and rock phosphate were compared, each with 5 rates of P banded, broadcast or spot-placed into the soil. After 2 wet seasons (66 weeks after planting), maximum tuber yields were produced by the banded application of 200 kg P/ha as triple superphosphate, 20 kg Mg/ha and 8 kg Zn/ha. With rock phosphate, only the broadcast placement produced an increase in the yield of cassava, maximum yields being achieved with 400 kg P/ha. In addition, there was evidence that 100 kg N/ha and 300 kg K/ha were needed for maximum yields. Therefore, based on the results of these individual experiments over 2 seasons, 100 kg N/ha, 200 kg P/ha as triple superphosphate or 400 kg P/ha as rock phosphate, 300 kg K/ha, 20 kg Mg/ha and 8 kg Zn/ha are the fertiliser recommendations for cassava grown in replaced soil at Weipa. In addition, early Zn deficiency symptoms (not related to any applied fertilisers) may necessitate a foliar spray of 4 kg Zn/ha as well as the soil-applied Zn fertiliser. However, the use of dolomite at 80 kg Mg/ha may have decreased the tuber yields and/or increased the requirements for certain soil-applied fertilisers. An average yield of 26.0 t/ha of tubers (fresh weight) was obtained with a 51-week growing season, and the recommended rates of fertilisers. This yield was reasonable when compared with 32 t/ha of fresh tubers predicted by a growth model for cassava, grown in North Queensland for 52 weeks without irrigation.
Farming systems in the Australian semi-arid tropics-a recent history
Authors: Chapman AL , Sturtz JD , Cogle AL , Mollah WS , Bateman RJ
Published: March 2005

The recent history of dryland farming in the Australian semi-arid tropics is discussed briefly against the background of national and state policies, established following World War II, aimed at increasing the population and development of northern Australia. Some reference is also made to irrigation as a means of overcoming limitations imposed by rainfall and to complement dryland farming systems. The environmental and socio-economic constraints whch have so far limited commercial agriculture in the Australian semi-arid tropics are highlighted. Efforts, particularly in north-west Australia, to develop sustainable farming systems based on legume pasture leys and livestock production in conjunction with annual cropping, as a basis for closer settlement, are reviewed. These attempts, which began in the 1960s and stemmed from earlier post-war agricultural research in the region, initially relied on a pasture legume (Stylosanthes humilis cv. Townsville stylo) and conventional tillage. Farming system development continues today using new legume species (e.g. Stylosanthes hamata cv. Verano and Centrosema pascuorum cv. Cavalcade) and no-tillage cropping technology. This paper documents the history of agricultural and research development, and commercial practice in the Australian semi-arid tropics.
Nitrogen supply to no-tillage crops, as influenced by mulch type, soil type and season, following pasture leys in the semi-arid tropics
Authors: Dimes JP , McCown RL , Saffigna PG
Published: March 2005

Past cropping research in the semi-arid tropics of northern Australia has shown that in this climate and on the predominantly sesquioxidic soils, recovery of fertiliser nitrogen (N) by crops is often low. Conceptually, no-tillage, legume ley farming offers features for coping better with the constraints of climate, soil and high fertiliser transport costs to this remote region. This paper summarises the N cycle in a system in which pastures provide N for successive crops, and mulch at the time of crop establishment is provided by the killing of new pasture growth. The aim was further to provide a sound foundation for managing N supply in relation to demand in a climate that causes high variation and uncertainty for pasture N2 fixation and sequestering, the amount of early season re-growth (mulch), rate of mulch decomposition, nitrate leaching losses, and crop growth and N demand. The research approach combined field studies with simulation modelling. A series of field studies that included bare fallow and grass and legume pasture leys on clay loam and sandy loam soils, were conducted at Katherine over 4 wet seasons to study subsequent mineralisation of N. Experimental results were used to test the performance of a simulation model for predicting the observed variations consequent upon the various management options. Experimental results showed that the carbon (C) : N ratio of the residue and soil texture were important factors in determining N mineralisation, immobifisation, and nitrate leaching following chemical kill of pasture leys. However, the greatest variation was between seasons. A modified version of the CERES-Maize N model was able to simulate the accumulation of nitrate following a bare fallow and following pasture leys with high levels (above and below ground) of freshly killed residues with widely differing C:N ratio, the downward movement of nitrate-N in the soil and the interaction of these processes with seasonal rainfall. Despite a capability for simulation of the soil N dynamics in a cropping phase following pasture leys, ex~erimental results indicated how nitrate distribution following leys is influenced by pasture growth during the ley, and how this varied greatly with season and soil texture. The simulation capability reported here has been incorporated elsewhere into the development of a full system model, embracing both the ley phase and the crop phase.
Nitrogen inputs from a pasture legume in rotations with cereals in the semi-arid tropics of northern Australia: experimentation and modelling on a clay loam soil
Authors: Jones RK , Probert ME , Dalgliesh NP , McCown RL
Published: March 2005

Two experiments on a Tippera clay loam soil (alfisol) at Katherine, Northern Territory, investigated the nitrogen (N) benefit from legume pasture leys of Caribbean stylo (Stylosanthes hamata cv. Verano) to subsequent maize crops. Nitrogen uptake and yield of the maize crops were higher after the Verano leys than after a grass ley, the effect persisting into the second crop. The 1-year Verano ley was estimated to have increased N uptake by the maize crops by about 30 kg/ha, and the 3-year ley by about 55 kgha over that for the grass. Removing some of the Verano dry matter (DM) as hay at the end of each growing season reduced the subsequent benefit compared with treatments where the Verano DM was rotovated into the surface soil at the end of each growing season, or left standing. However, in all legume treatments, the additional N contributed by the legume was inadequate to fully meet the N requirement of the following crop. The main features of the experimental results, through both the ley and cropping phases, could be simulated adequately using the cropping system model APSIM. The model provided the opportunity to explore the fate of N in the system, and gave insights into aspects of system performance that could not be obtained from the experimental data.
Simulation of a legume ley farming system in northern Australia using the Agricultural Production Systems Simulator
Authors: Carberry PS , McCown RL , Muchow RC , Dimes JP , Probert ME , Poulton PL , Dalgliesh NP
Published: March 2005

An innovative ley farming system, involving cereal crops grown in rotation with pasture legumes, has been tentatively adopted by farmers in the semi-arid tropics of northern Australia. Yet, after more than a decade of experimental research, the long-term
A contact-activated kinase signals
Candida albicans
invasive growth and biofilm development
Authors: Kumamoto Carol A.
Published: March 2005

For mammalian cells, contact-dependent regulatory controls are crucially important for controlling cellular proliferation and preventing diseases such as cancer.
Candida albicans
, an opportunistic fungal pathogen that normally resides within a mammalian host, also exhibits contact-dependent cellular behaviors such as invasive hyphal growth and biofilm development. Results reported here demonstrate that, in
C. albicans
, physical contact results in activation of the mitogen-activated protein kinase Mkc1p. This kinase is part of the fungal cell integrity pathway, a signal transduction pathway known to be activated by cell wall stress. It is demonstrated here that Mkc1p is required for invasive hyphal growth and normal biofilm development. Therefore, Mkc1p signaling contributes to contact-dependent regulation. Because responding to contact appropriately allows coordinated cellular behavior in a metazoan, commensal
C. albicans
cells behave like a part of the host, using contact-activated signaling to regulate fungal behavior.
Glutamate receptor activation triggers a calcium-dependent and SNARE protein-dependent release of the gliotransmitter D-serine
Authors: Mothet Jean-Pierre , Pollegioni Loredano , Ouanounou Gilles , Martineau Magalie , Fossier Philippe , Baux Gérard
Published: March 2005

The gliotransmitterd-serine is released upon (S)-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate and metabotropic glutamate receptor stimulation, but the mechanisms involved are unknown. Here, by using a highly sensitive bioassay to continuously monitor extracellulard-serine levels, we have investigated the pathways used in its release. We reveal thatd-serine release is inhibited by removal of extracellular calcium and augmented by increasing extracellular calcium or after treatment with the Ca2+ionophore A23187. Furthermore, release of the amino acid is considerably reduced after depletion of thapsigargin-sensitive intracellular Ca2+stores or chelation of intracellular Ca2+with 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetate–acetoxymethyl ester. Interestingly,d-serine release also was markedly reduced by concanamycin A, a vacuolar-type H+-ATPase inhibitor, indicating a role for the vesicular proton gradient in the transmitter storage/release. In addition, agonist-evokedd-serine release was sensitive to tetanus neurotoxin. Finally, immunocytochemical and sucrose density gradient analysis revealed that a large fraction ofd-serine colocalized with synaptobrevin/VAMP2, suggesting that it is stored in VAMP2-bearing vesicles. In summary, our study reveals the cellular mechanisms subservingd-serine release and highlights the importance of the glial cell exocytotic pathway in influencing CNS levels of extracellulard-serine.
Conformational transition of amyloid β-peptide
Authors: Xu Yechun , Shen Jianhua , Luo Xiaomin , Zhu Weiliang , Chen Kaixian , Ma Jianpeng , Jiang Hualiang
Published: March 2005

The amyloid β-peptides (Aβs), containing 39–43 residues, are the key protein components of amyloid deposits in Alzheimer's disease. To structurally characterize the dynamic behavior of Aβ
40
, 12 independent long-time molecular dynamics (MD) simulations for a total of 850 ns were performed on both the wide-type peptide and its mutant in both aqueous solution and a biomembrane environment. In aqueous solution, an α-helix to β-sheet conformational transition for Aβ
40
was observed, and an entire unfolding process from helix to coil was traced by MD simulation. Structures with β-sheet components were observed as intermediates in the unfolding pathway of Aβ
40
. Four glycines (G
25
, G
29
, G
33
, and G
37
) are important for Aβ
40
to form β-sheet in aqueous solution; mutations of these glycines to alanines almost abolished the β-sheet formation and increased the content of the helix component. In the dipalmitoyl phosphatidylcholine (DPPC) bilayer, the major secondary structure of Aβ
40
is a helix; however, the peptide tends to exit the membrane environment and lie down on the surface of the bilayer. The dynamic feature revealed by our MD simulations rationalized several experimental observations for Aβ
40
aggregation and amyloid fibril formation. The results of MD simulations are beneficial to understanding the mechanism of amyloid formation and designing the compounds for inhibiting the aggregation of Aβ and amyloid fibril formation.
Decline in skeletal muscle mitochondrial function with aging in humans
Authors: Short Kevin R. , Bigelow Maureen L. , Kahl Jane , Singh Ravinder , Coenen-Schimke Jill , Raghavakaimal Sreekumar , Nair K. Sreekumaran
Published: March 2005

Cumulative mtDNA damage occurs in aging animals, and mtDNA mutations are reported to accelerate aging in mice. We determined whether aging results in increased DNA oxidative damage and reduced mtDNA abundance and mitochondrial function in skeletal muscle of human subjects. Studies performed in 146 healthy men and women aged 18–89 yr demonstrated that mtDNA and mRNA abundance and mitochondrial ATP production all declined with advancing age. Abundance of mtDNA was positively related to mitochondrial ATP production rate, which in turn, was closely associated with aerobic capacity and glucose tolerance. The content of several mitochondrial proteins was reduced in older muscles, whereas the level of the oxidative DNA lesion, 8-oxo-deoxyguanosine, was increased, supporting the oxidative damage theory of aging. These results demonstrate that age-related muscle mitochondrial dysfunction is related to reduced mtDNA and muscle functional changes that are common in the elderly.
Functional genomic analysis of the rates of protein evolution
Authors: Wall Dennis P. , Hirsh Aaron E. , Fraser Hunter B. , Kumm Jochen , Giaever Guri , Eisen Michael B. , Feldman Marcus W.
Published: March 2005

The evolutionary rates of proteins vary over several orders of magnitude. Recent work suggests that analysis of large data sets of evolutionary rates in conjunction with the results from high-throughput functional genomic experiments can identify the factors that cause proteins to evolve at such dramatically different rates. To this end, we estimated the evolutionary rates of >3,000 proteins in four species of the yeast genusSaccharomycesand investigated their relationship with levels of expression and protein dispensability. Each protein's dispensability was estimated by the growth rate of mutants deficient for the protein. Our analyses of these improved evolutionary and functional genomic data sets yield three main results. First, dispensability and expression have independent, significant effects on the rate of protein evolution. Second, measurements of expression levels in the laboratory can be used to filter data sets of dispensability estimates, removing variates that are unlikely to reflect real biological effects. Third, structural equation models show that although we may reasonably infer that dispensability and expression have significant effects on protein evolutionary rate, we cannot yet accurately estimate the relative strengths of these effects.
The Burger-Sarnak method and operations on the unitary dual of 𝐺𝐿(𝑛)
Authors: Venkatesh Akshay
Published: March 2005

We study the effect of restriction to Levi subgroups, induction from Levi subgroups, and tensor product, on unitary representations of

G
L

(
n
)

\mathrm {GL}(n)

over a local field

k
k

. These results give partial answers to questions raised by Clozel.
Human ether-a-go-go-related Gene 1 Channels Are Physically Linked to β1 Integrins and Modulate Adhesion-dependent Signaling
Authors: Cherubini Alessia , Hofmann Giovanna , Pillozzi Serena , Guasti Leonardo , Crociani Olivia , Cilia Emanuele , Di Stefano Paola , Degani Simona , Balzi Manuela , Olivotto Massimo , Wanke Enzo , Becchetti Andrea , Defilippi Paola , Wymore Randy , Arcangeli Annarosa
Published: March 2005

Adhesive receptors of the integrin family are primarily involved in cell–extracellular matrix adhesion. Additionally, integrins trigger multiple signaling pathways that are involved in cell migration, proliferation, survival, and differentiation. We previously demonstrated that the activation of integrins containing the β1 subunit leads to a selective increase in potassium currents carried by the human ether-a-go-go-related gene (hERG) channels in neuroblastoma and leukemia cells; this current activation modulates adhesion-dependent differentiation in these cells. We hypothesized that the cross-talk between integrins and hERG channels could be traced back to the assembly of a macromolecular signaling complex comprising the two proteins. We tested this hypothesis in both SH-SY5Y neuroblastoma cells and in human embryonic kidney 293 cells stably transfected with hERG1 and, therefore, expressing only the full-length hERG1 protein on the plasma membrane. The β1 integrin and hERG1 coprecipitate in these cells and colocalize in both intracellular and surface membrane compartments. The two proteins also coprecipitate with caveolin-1, suggesting the localization of the complex in lipid rafts/caveolae. hERG1-transfected cells undergo an activation of hERG currents after β1 integrin-mediated adhesion to fibronectin; concomitant with this activation, the focal adhesion kinase associates with the hERG1 protein and becomes tyrosine phosphorylated. Using hERG1-specific inhibitors, we show that the tyrosine phosphorylation of focal adhesion kinase is strictly dependent on hERG channel activity. Similarly, the activity of the small GTPase Rac1 turned out to be dependent on hERG currents. On the whole, these data indicate that the hERG1 protein associates with β1 integrins and modulates adhesion receptor signaling.
Neutrophil Migration across Tight Junctions Is Mediated by Adhesive Interactions between Epithelial Coxsackie and Adenovirus Receptor and a Junctional Adhesion Molecule-like Protein on Neutrophils
Authors: Zen Ke , Liu Yuan , McCall Ingrid C. , Wu Tao , Lee Winston , Babbin Brian A. , Nusrat Asma , Parkos Charles A.
Published: March 2005

Neutrophil (polymorphonuclear leukocytes [PMN]) transepithelial migration during inflammatory episodes involves a complex series of adhesive interactions and signaling events. Previous studies have shown that key adhesive interactions between leukocyte CD11b/CD18 and basally expressed fucosylated glycoproteins followed by binding to desmosomal-associated JAM-C are key elements of the transmigration response. Here we provide the first evidence that PMN-expressed junctional adhesion molecule-like protein (JAML) regulates transmigration via binding interactions with epithelial coxsackie and adenovirus receptor (CAR). Experiments with a JAML fusion protein revealed specific binding of JAML to epithelial CAR expressed at tight junctions in T84 cell monolayers and normal human colonic mucosa. Furthermore, JAML-CAR binding is mediated via the membrane distal immunoglobulin (Ig) loop of CAR and the membrane proximal Ig loop of JAML. PMN bound to immobilized CAR but not JAML in a divalent cation-independent manner. Lastly, in assays of PMN transepithelial migration, JAML/CAR fusion proteins and their antibodies significantly inhibited transmigration in a specific manner. Taken together, these results indicate that JAML and CAR are a novel pair of adhesion molecules that play an important role in modulating PMN migration cross epithelial tight junctions. These findings add a new element to a multistep model of PMN transepithelial migration and may provide new targets for anti-inflammatory therapies.
Differential Roles for Actin Polymerization and a Myosin II Motor in Assembly of the Epithelial Apical Junctional Complex
Authors: Ivanov Andrei I. , Hunt Dirk , Utech Markus , Nusrat Asma , Parkos Charles A.
Published: March 2005

Differentiation and polarization of epithelial cells depends on the formation of the apical junctional complex (AJC), which is composed of the tight junction (TJ) and the adherens junction (AJ). In this study, we investigated mechanisms of actin reorganization that drive the establishment of AJC. Using a calcium switch model, we observed that formation of the AJC in T84 intestinal epithelial cells began with the assembly of adherens-like junctions followed by the formation of TJs. Early adherens-like junctions and TJs readily incorporated exogenous G-actin and were disassembled by latrunculin B, thus indicating dependence on continuous actin polymerization. Both adherens-like junctions and TJs were enriched in actin-related protein 3 and neuronal Wiskott-Aldrich syndrome protein (N-WASP), and their assembly was prevented by the N-WASP inhibitor wiskostatin. In contrast, the formation of TJs, but not adherens-like junctions, was accompanied by recruitment of myosin II and was blocked by inhibition of myosin II with blebbistatin. In addition, blebbistatin inhibited the ability of epithelial cells to establish a columnar phenotype with proper apico-basal polarity. These findings suggest that actin polymerization directly mediates recruitment and maintenance of AJ/TJ proteins at intercellular contacts, whereas myosin II regulates cell polarization and correct positioning of the AJC within the plasma membrane.
p115 Interacts with the GLUT4 Vesicle Protein, IRAP, and Plays a Critical Role in Insulin-stimulated GLUT4 Translocation
Authors: Hosaka Toshio , Brooks Cydney C. , Presman Eleonora , Kim Suk-Kyeong , Zhang Zidong , Breen Michael , Gross Danielle N. , Sztul Elizabeth , Pilch Paul F.
Published: March 2005

Insulin-regulated aminopeptidase (IRAP) is an abundant cargo protein of Glut4 storage vesicles (GSVs) that traffics to and from the plasma membrane in response to insulin. We used the amino terminus cytoplasmic domain of IRAP, residues 1–109, as an affinity reagent to identify cytosolic proteins that might be involved in GSV trafficking. In this way, we identified p115, a peripheral membrane protein known to be involved in membrane trafficking. In murine adipocytes, we determined that p115 was localized to the perinuclear region by immunofluorescence and throughout the cell by fractionation. By immunofluorescence, p115 partially colocalizes with GLUT4 and IRAP in the perinuclear region of cultured fat cells. The amino terminus of p115 binds to IRAP and overexpression of a N-terminal construct results in its colocalization with GLUT4 throughout the cell. Insulin-stimulated GLUT4 translocation is completely inhibited under these conditions. Overexpression of p115 C-terminus has no significant effect on GLUT4 distribution and translocation. Finally, expression of the p115 N-terminus construct has no effect on the distribution and trafficking of GLUT1. These data suggest that p115 has an important and specific role in insulin-stimulated Glut4 translocation, probably by way of tethering insulin-sensitive Glut4 vesicles at an as yet unknown intracellular site.
Competitive suppression in mixed-clone parasite cultures
Authors: Taylor Louise H , Matthews Louise , Shaw Darren J , Haydon Daniel T
Published: March 2005

Mixed-genotype infections occur frequently in natural populations. Parasite genotypes are expected to interact within a host: competing for shared nutrients and being affected by the host's immune response to each other. Theoretically, competing parasites can be expected to exhibit increased rates of replication. Here, we investigate whether interactions between clones of
Theileria annulata
, a protozoan parasite of cattle, affect clones' replication rates in mixed cultures
in vitro
. Intrinsic replication rates and carrying capacities estimated from single-clone control cultures were used to predict replication rates of mixed cultures under different competitive assumptions. Mixed-culture dynamics deviated significantly from expectations in five out of six different clone combinations tested. Contrary to expectation, mixed cultures often replicated more slowly than predicted from single-clone control cultures. Competition coefficients were then calculated from the mixed-culture data and a competitive hierarchy of clones determined. The results also suggest that inherent competitive ability may be greater in clones with lower carrying capacities—those clones which would otherwise be excluded in a genetically diverse environment. Moreover, significant negative deviations from expected replication rates corresponded with successful out-competing of a higher carrying capacity clone by a lower carrying capacity clone.
Bite club: comparative bite force in big biting mammals and the prediction of predatory behaviour in fossil taxa
Authors: Wroe Stephen , McHenry Colin , Thomason Jeffrey
Published: March 2005

We provide the first predictions of bite force (B
S
) in a wide sample of living and fossil mammalian predators. To compare between taxa, we calculated an estimated bite force quotient (BFQ) as the residual of B
S
regressed on body mass. Estimated B
S
adjusted for body mass was higher for marsupials than placentals and the Tasmanian devil (
Sarcophilus harrisii
) had the highest relative B
S
among extant taxa. The highest overall B
S
was in two extinct marsupial lions. BFQ in hyaenas were similar to those of related, non-osteophagous taxa challenging the common assumption that osteophagy necessitates extreme jaw muscle forces. High BFQ in living carnivores was associated with greater maximal prey size and hypercarnivory. For fossil taxa anatomically similar to living relatives, BFQ can be directly compared, and high values in the dire wolf (
Canis dirus
) and thylacine (
Thylacinus cynocephalus
) suggest that they took relatively large prey. Direct inference may not be appropriate where morphologies depart widely from biomechanical models evident in living predators and must be considered together with evidence from other morphological indicators. Relatively low BFQ values in two extinct carnivores with morphologies not represented among extant species, the sabrecat,
Smilodon fatalis
, and marsupial sabretooth,
Thylacosmilus atrox
, support arguments that their killing techniques also differed from extant species and are consistent with ‘canine-shear bite’ and ‘stabbing’ models, respectively. Extremely high BFQ in the marsupial lion,
Thylacoleo carnifex
, indicates that it filled a large-prey hunting niche.
A natural hybrid of Leuciscus cephalus (L.) and Chalcalburnus chalcoides (Güldenstädt)(Osteichthyes‐Cyprinidae) from Lake Tödürge (Sivas, Turkey)
Authors: Ünver B. , Erk’akan F.
Published: March 2005

Hybridization between Leuciscus cephalus and Chalcalburnus chalcoides was identified from biometrical features in 55 fish caught from Lake Tödürge, Sivas, Turkey, between April 1994 and November 1997. The hybrid index Vh for metric and meristic characters was intermediate (Vh = 45·6) compared with their parents (L. cephalus Vh = 0 or negative and C. chalcoides Vh ≥ 100). Morphological, metric and meristic features of L. cephalus × C. chalcoides also resembled those of the parents. The majority presented an intermediate position which was best shown by the shape of mouth, caudal fin, gill rakers and pharyngeal teeth, and also by the caudal peduncle depth, head and interorbital width, predorsal and preanal distance, height of anal fin, length of anal base and other characters.
Growth, sex differentiation and gonad and plasma levels of sex steroids in male‐ and female‐dominant populations of Dicentrarchus labrax obtained through repeated size grading
Authors: Papadaki M. , Piferrer F. , Zanuy S. , Maingot E. , Divanach P. , Mylonas C. C.
Published: March 2005

Starting from 66 days post hatching (dph), European sea bass Dicentrarchus labrax were graded successively to create a fast growing (L‐extreme) and a slow growing (S‐extreme) population. The L‐extreme population grew significantly larger (ANOVA, n = 89–101, P < 0·01) attaining twice the wet mass of the S‐extreme population at 300 dph (130·9 ± 1·8 v. 66·7 ± 0·9 g, mean ± s.e.). When the two populations were sexed, the L‐extreme consisted of 96·5% and the S‐extreme of 30·2% females, while the ungraded control had 59·2% females. Sex differentiation began first in females at a total length (LT) of 97 ± 4 mm and wet mass of 9·4 ± 1·2 g (150 dph), and was completed when fish reached 166 ± 6 mm and 53·4 ± 6·4 g (250 dph) in both sexes. Precocious maturation in males was positively correlated to growth. Gonad oestradiol (E2) was significantly higher in the female‐dominant population at the onset of ovarian differentiation (ANOVA, n = 10, P < 0·05) and in the plasma after the appearance of the first primary oocytes (P < 0·01). Gonad testosterone (T) increased in both populations after sex differentiation (ANOVA, n = 10, P < 0·05), while plasma levels were significantly higher in the male‐dominant population (P < 0·001). Both gonad and plasma 11‐keto testosterone (11‐KT) were significantly higher in the male‐dominant population (ANOVA, n = 10, P < 0·01) reaching maximal values at spermiation. The results suggest that E2 is closely related with ovarian differentiation and the onset of oogenesis, while T and 11‐KT is more related to spermatogenesis and precocious maturation.
Cannibalism in Arctic charr: do all individuals have the same propensity to be cannibals?
Authors: Svenning M.‐A. , Borgstrøm R.
Published: March 2005

By comparing large Arctic charrSalvelinus alpinus, which had shown a persistent cannibalistic response varying from zero to very high in succeeding laboratory trials, with their individual cannibalistic behaviour after release into a natural lake inhabited by small Arctic charr, it was found that all Arctic charr had the potential to become cannibalistic, irrespective of their laboratory behaviour. More specifically, Arctic charr that never fed on prey fishes when offered them in the tank experiments turned to cannibalism when released in the lake, highlighting the potential difficulties in extrapolating laboratory results to natural settings. This was also true for naive fish that had no prior experience of eating live food. Since no significant increase in the number of prey consumed during each of the succeeding laboratory trials was found, and naive fish showed a response under natural conditions similar to that of their counterparts, the training of the Arctic charr (or experience or learning) probably had no effect upon the piscivorous or cannibalistic response after stocking. Thus, the study appeared to demonstrate that most variations in cannibalism in Arctic charr was simply a function of environmental conditions, depending on the density of conspecificsv. alternative prey, and the relative size difference between predator and prey, rather than any genetic influence.
Pelagic marine feeding of Arctic charr and sea trout
Authors: Rikardsen A. H. , Amundsen P.‐A.
Published: March 2005

In a fjord in northern Norway, both immature and maturing individuals (170–500 mm fork length) of anadromous Arctic charrSalvelinus alpinusand anadromous brown trout (sea trout)Salmo truttawere captured up to 5000 m offshore. Both species had a high feeding intensity and an almost exclusive piscivorous diet, with herringClupea harengusas the dominant prey, an apparently opportunistic response to a high density of small‐sized herring in the pelagic zone.
Early development of the head skeleton in Brycon moorei(Pisces, Ostariophysi, Characidae)
Authors: Vandewalle P. , Germeau G. , Besancenet P. , Parmentier E. , Baras E.
Published: March 2005

At hatching (15 h post fertilization), Brycon moorei possesses no skeletal structure. Thereafter, development is very rapid. The first oral teeth appear no later than 3 h post‐hatching, but they remain covered with epithelium until c. 45 h. At 7 h, the trabecular bars and part of the cartilaginous visceral arches are visible and at 15 h, the dentaries and premaxillaries are present. At 25 h, i.e. the onset of piscivory and cannibalism (the yolk sac is only fully resorbed after 36 h), the oral teeth are fully developed, the first pharyngeal teeth are formed, and some head movements already appear synchronized, but the mouth cavity is not completely isolated from the neurocranium by bony structures. Thereafter, no new buccal or pharyngeal bony structure is visible until 45 h, when the maxilla and opercula appear, along with a new type of cannibalistic behaviour. Cartilage resorptions also start at 45 h, but with no concomitant replacement by formation of calcified structures. Later, development gradually becomes similar to that of many previously studied teleosts. The developmental pattern of B. moorei is thus extremely rapid in comparison with other teleosts, i.e. it prioritizes feeding structures that permit the expression of piscivory at a very early age. The uniqueness of this pattern is discussed in relation to ecological constraints on early feeding and fast growth.
Response to conspecific and heterospecific alarm cues by pumpkinseeds in simple and complex habitats: field verification of an ontogenetic shift
Authors: Golub J. L. , Vermette V. , Brown G. E.
Published: March 2005

Three focal size classes [small (<40 mm, standard length, LS), medium (40–80 mm LS) and large (>80 mm LS)] of pumpkinseed Lepomis gibbosus were exposed to conspecific or one of three heterospecific chemical alarm cues under one of three levels of habitat complexity (low, intermediate and high). Under low and intermediate habitat complexities, pumpkinseeds <80 mm LS exhibited a significant antipredator response when exposed to the chemical alarm cues of heterospecific prey guild members (largemouth bass Micropterus salmonides and hypoxanthine‐3‐N‐oxide, the putative Ostariophysan alarm ‘pheromone’), while pumpkinseeds >80 mm LS exhibited a foraging response. Under highly complex habitats, pumpkinseeds of all three size classes exhibited an antipredator response. Moreover, under all three habitat conditions, pumpkinseeds of all size classes exhibited an antipredator response to conspecific alarm cues. There was no change in behaviour under any treatment combination in response to an allopatric heterospecific control (swordtails Xiphophorus helleri). These results provide the first field verification of the size dependent use of chemical alarm cues by centrarchids and demonstrate that microhabitat complexity significantly influences the threat‐sensitive use of these cues.
Genetic identification of cryptic juveniles of little skate and winter skate
Authors: Alvarado Bremer J. R. , Frisk M. G. , Miller T. J. , Turner J. , Viñas J. , Kwil K.
Published: March 2005

As the morphological discrimination of winter skate Leucoraja ocellata and little skate Leucoraja erinacea juveniles is unreliable, a genetic assay, based on the restriction digest with Sty I of a segment of mitochondrial DNA cytochrome oxidase I gene, capable of discriminating the species was developed. The reliable identification of species can be used to improve the accuracy of population assessment models.
American paddlefish leukocytes demonstrate mammalian‐like cytochemical staining characteristics in lymphoid tissues
Authors: Petrie‐Hanson L. , Peterman A. E.
Published: March 2005

American paddlefish Polyodon spathula leukocytes demonstrated cytoplasmic staining patterns very similar to mammalian leukocytes when stained with acid phosphatase, α‐naphthyl butyrate esterase and β‐glucuronidase. American paddlefish monocytes, lymphocytes and granulocytes stained positive for acid phosphatase. Monocytes stained positive for α‐naphthyl butyrate esterase. Lymphocytes that stained positive for α‐naphthyl butyrate esterase were designated type A. Lymphocytes that stained positive with antibodies to the L chain of white sturgeon Acipenser transmontanus immunoglobulin (Ig) were designated type B. Type A and type B lymphocytes stained positive for β‐glucuronidase. All leukocytes observed were negative for Sudan Black B. Monocytes, lymphocytes and granulocytes were present in the renal haematopoietic tissue, spleen, thymus, pericardial myeloid tissue, lamina propria of the spiral valve, and in meningeal myeloid tissue located dorsal to the brain, at the base of the brain and around the notochord. Peyer's patches were present in the gut. Morphological characteristics of leukocytes stained with Wright's and haematoxylin and eosin and appeared very similar to those of other fish species.
Exact Solutions of Compressible Flow Equations with Spherical Symmetry
Authors: Sachdev P. L. , Joseph K. T. , Haque M. Ejanul
Published: March 2005

In this paper, we construct spherically symmetric solutions of the equations of compressible flow, which are important in the theory of explosion waves in air, water, and other media. Following McVittie [1], we write a general solution form, in terms of velocity potential, as a product of a function of time and a function of a similarity variable. First, we find solutions to the equations of motion and continuity without reference to adiabatic or isentropic relation. These solutions are quite general and can be applied to nonadiabatic motions, such as the motions of interstellar gas clouds that lose energy by radiation. All the solutions found by McVittie [1] have linear velocity profile with respect to distance. We introduce a nonlinear form of the velocity function containing an arbitrary function of the similarity variable. Adiabatic conditions lead to a second‐order ODE, which we discuss in some detail. We relate our work to the earlier investigations of Taylor [2], McVittie [1], and Keller [3].
Wave Breaking and the Generation of Undular Bores in an Integrable Shallow Water System
Authors: El G. A. , Grimshaw R. H. J. , Kamchatnov A. M.
Published: March 2005

The generation of an undular bore in the vicinity of a wave‐breaking point is considered for the integrable Kaup–Boussinesq (KB) shallow water system. In the framework of the Whitham modulation theory, an analytic solution of the Gurevich–Pitaevskii type of problem for a generic “cubic” breaking regime is obtained using a generalized hodograph transform, and a further reduction to a linear Euler–Poisson equation. The motion of the undular bore edges is investigated in detail.
Fragment shape and tree species composition in tropical forests: a landscape level investigation
Authors: Hill J. L. , Curran P. J.
Published: March 2005

Fragmentation of tropical forest alters community composition as a result of changes in forest shape. This paper uses 22 hypotheses to test the effect of fragment shape on tree species composition in Ghana, West Africa, within biological categories of regeneration guild, rarity, phenology and dispersal. For both regenerating and mature trees, relationships between species composition and the shape of forest fragments were complex; almost half were significant but many failed to support the established hypotheses. Irregular shaped fragments had high proportions of regenerating, light‐demanding pioneers and mature, animal‐dispersed species. Species common to Ghana formed the foundation of communities in fragments of all shapes. Investigation at the landscape level indicated broad patterns of species change. Rigorous hypothesis testing is needed, following extensive demographic work on the ground, before population dynamics within tropical forest fragments can be comprehended fully and applied to conservation management.
Temporal patterns of crop raiding by elephants: a response to changes in forage quality or crop availability?
Authors: Chiyo Patrick I. , Cochrane Erica P. , Naughton Lisa , Basuta Gilbert I.
Published: March 2005

Temporal patterns of crop raiding by elephants were studied for 13 months in 1996/1997 at Kibale Forest National Park, Uganda. To determine the influence of environmental factors on the timing of raiding, we tested for correlations between crop raiding patterns and the quality of natural forage within the forest as well as crop availability beyond park boundaries. Crop raiding occurred throughout the year with peaks in dry seasons when crop availability was high. Bananas and maize were the main crops raided. Variations in forage quality were moderate with small seasonal fluctuations and peaks in dry seasons. Monthly crop raiding incidences were not influenced by forage quality but by ripening of maize. Comparison of forage quality and temporal distribution of crop raiding between savanna and forest habitats suggests that crop availability is more important in forest habitats, whereas in savanna habitats large seasonal fluctuations in forage quality have a greater influence on temporal patterns of crop raiding.
The world's biogeographical regions: cluster analyses based on bat distributions
Authors: Procheş Şerban
Published: March 2005

Aim  Both floral kingdoms and faunal regions have so far been intuitively defined. This study was conducted to compare these with an analytical regionalization based on cluster analyses in a fairly homogeneous, globally distributed group of organisms: the bats (order Chiroptera). This comparison was used to discuss the possibilities of employing clustering techniques in global biogeography.

Location  The study considered bat distributions world‐wide.

Methods  Analyses were conducted both for presence/absence of genera and species, and for the number of species in each genus. Clusters distinguished at selected dissimilarity values were mapped.

Results  A set of c. 10 regional clusters recurred in the analyses, broadly corresponding not only to the world's accepted faunal regions and subregions, but also to the floral kingdoms and subkingdoms.

Main conclusions  This study is an analytical confirmation of the fact that similar global distribution patterns are to be found in different groups of organisms. Cluster analyses can be used to refine global regionalization schemes, and, with the accumulation of such data for different taxa and ecologically defined groups, shared patterns can be used to draft one common global biogeographical regionalization. At the same time, differences between the regionalization schemes derived for different groups can be used to partial out the role of dispersal abilities, body size, evolutionary age, etc., in determining global distribution patterns.
Characterization of moorland vegetation and the prediction of bird abundance using remote sensing
Authors: Buchanan Graeme , Pearce‐Higgins James , Grant Murray , Robertson Duncan , Waterhouse Tony
Published: March 2005

Aims  To characterize and identify upland vegetation composition and height from a satellite image, and assess whether the resulting vegetation maps are accurate enough for predictions of bird abundance.

Location  South‐east Scotland, UK.

Methods  Fine‐taxa vegetation data collected using point samples were used for a supervised classification of a Landsat 7 image, while linear regression was used to model vegetation height over the same image. Generalized linear models describing bird abundance were developed using field‐collected bird and vegetation data. The satellite‐derived vegetation data were substituted into these models and efficacy was examined.

Results  The accuracy of the classification was tested over both the training and a set of test plots, and showed that more common vegetation types could be predicted accurately. Attempts to estimate the heights of both dwarf shrub and graminoid vegetation from satellite data produced significant, but weak, correlations between observed and predicted height. When these outputs were used in bird abundance–habitat models, bird abundance predicted using satellite‐derived vegetation data was very similar to that obtained when the field‐collected data were used for one bird species, but poor estimates of vegetation height produced from the satellite data resulted in a poor abundance prediction for another.

Conclusions  This pilot study suggests that it is possible to identify moorland vegetation to a fine‐taxa level using point samples, and that it may be possible to derive information on vegetation height, although more appropriate field‐collected data are needed to examine this further. While remote sensing may have limitations compared with relatively fine‐scale fieldwork, when used at relatively large scales and in conjunction with robust bird abundance–habitat association models, it may facilitate the mapping of moorland bird abundance across large areas.