bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil water repellency in north-eastern Greece with adverse effects of drying on the persistence
Authors: Ziogas Apostolos K. , Ritsema Coen J. , Oostindie Klaas , Dekker Louis W.
Published: May 2005

Many soils may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard water infiltration into the soil matrix. Soil water repellency often leads to the development of unstable wetting and preferential flow paths. In the present study the persistence of water repellency was examined on samples from topsoils in Thrace, north-eastern Greece, using the Water Drop Penetration Time (WDPT) test. The soil samples were collected from agricultural fields throughout the prefectures of Xanthi and Rodopi. Six sites were selected for intensive sampling of water repellency and soil moisture content in transects. Water repellency was measured on field-moist soil samples and after drying the samples at increasing temperatures, to study the influence of drying temperature on the persistence of soil water repellency. Measurements of soil samples taken in agricultural fields under different crops, e.g. winter wheat, tobacco, clover, olive groves, kiwi fruit, and vineyards, in the area of Thrace, revealed that 45% of the locations exhibited actual water repellency during dry periods. Drying of samples from the Sostis site resulted in wettable soil, whereas drying of samples from the Mitriko site increased repellency. Therefore, water repellency should preferably be measured on samples taken in the field under dry conditions in order to reveal and determine the highest persistence of water repellency that might occur in the field.
Effects of surfactant treatments on the wettability of a water repellent grass-covered dune sand
Authors: Dekker Louis W. , Oostindie Klaas , Kostka Stanley J. , Ritsema Coen J.
Published: May 2005

The objective of this study was to evaluate the effectiveness of the surfactant formulation Primer®604 for amelioration and management of soil water repellency in grass-covered dune sand. The soil is severely to extremely water repellent to a depth of >0.50 m during dry periods. Primer®604 was applied 12 times between 22 April and 23 November 1999. During that period, soil samples were taken in the untreated and treated plot—8 times in transects and 2 times in soil blocks. A total of 4950 samples were collected for assessment of the actual water repellency and for the spatial and temporal variability of the water content of the soil. Resistance to wetting was determined by measuring the wetting rate of field-moist samples. Measurements of water repellency revealed that applications of Primer®604 resulted in less persistent water repellency in the surface layer to a depth of 0.05 m. No effects were observed deeper in the soil profile, likely due to adsorption of the surfactant material in the surface layer. In the surface layer (0–0.025 and 0.025–0.05 m), the critical soil water content below which the soil is actually water repellent in the field was lowered distinctly by the application of Primer®604, potentially due to coating of water repellent particle surfaces by the surfactant. This suggests that the surface layer (0–0.05 m) in the Primer®604-treated soil can dry to lower water contents than in the untreated soil before water repellency is induced. The thatch layer (0–0.025 m) of the treated soil was often found to have slightly higher water contents than of the untreated soil. The surfactant did not equalise the uneven moisture distribution in the soil below the surface layer (0–0.05 m). Primer®604 applications increased the wetting rate of field-moist samples from the thatch layer. This may result in a more effective wetting of the root-zone during rain events or irrigation, and a reduction in runoff.
Extraction of compounds associated with water repellency in sandy soils of different origin
Authors: Doerr S. H. , Llewellyn C. T. , Douglas P. , Morley C. P. , Mainwaring K. A. , Haskins C. , Johnsey L. , Ritsema C. J. , Stagnitti F. , Allinson G. , Ferreira D. , Keizer J. J. , Ziogas A. K. , Diamantis J.
Published: May 2005

After an initial evaluation of several solvents, the efficiency of Soxhlet extractions with isopropanol/ammonia (s.g. 0.88) (70 : 30 v : v; 24 h) in extracting compounds associated with water repellency in sandy soils was examined using a range of repellent and wettable control soils (n = 15 and 4) from Australia, Greece, Portugal, The Netherlands, and the UK. Extraction efficiency and the role of the extracts in causing soil water repellency was examined by determining extract mass, sample organic carbon content and water repellency (after drying at 20°C and 105°C) pre- and post-extraction, and amounts of aliphatic C–H removed using DRIFT, and by assessing the ability of extracts to cause repellency in acid-washed sand (AWS).
Key findings are: (i) none of organic carbon content, amount of aliphatic C–H, or amount of material extracted give any significant correlation with repellency for this diverse range of soils; (ii) sample drying at 105°C is not necessarily useful before extraction, but may provide additional information on extraction effectiveness when used after extraction; (iii) the extraction removed repellency completely from 13 of the 15 repellent samples; (iv) extracts from all repellent and wettable control soils were capable of inducing repellency in AWS. The findings suggest that compounds responsible for repellency represent only a fraction of the extract composition and that their presence does not necessarily always cause repellency.
Effects of heating and post-heating equilibration times on soil water repellency
Authors: Doerr S. H. , Douglas P. , Evans R. C. , Morley C. P. , Mullinger N. J. , Bryant R. , Shakesby R. A.
Published: May 2005

The effects of variation in heating temperature T (50–300°C), heating duration (20–60 min), and post-heating equilibration times (24–168 h at 20°C and 50% relative humidity) on the wettability, as measured by the Critical Surface Tension (CST) method, of 4 initially water repellent soils from Canada, Portugal, and the UK are reported. All soils show an increase in water repellency following heating at temperatures in the range of 50 to 150°C, followed by a considerable decline after heating to 200–250°C, and, except for one soil, the eradication of repellency after heating to 300°C. For two soils with a comparatively high organic carbon content and fine texture, water repellency levels were also affected by the length of the post-heating equilibration period.
The results demonstrate that (i) the common practice of heating samples to 105°C does not provide a viable standard procedure for the measurement of water repellency as it may alter repellency to different degrees, and (ii) where heat treatment is required, a post-heating equilibration time of 24 h is not necessarily sufficient for sample repellency levels to adjust to atmospheric laboratory conditions; therefore it is advisable to prolong equilibration to at least one week prior to measurement.
Assessment of the application of percolation theory to a water repellent soil
Authors: Steenhuis Tammo S. , Hunt Allen G. , Parlange J.-Yves , Ewing Robert P.
Published: May 2005

A few hydrophobic grains in otherwise hydrophilic sand render the soil hydrophobic and can completely alter the flow of water through unsaturated sands. In this paper we examine whether percolation theory can explain the phenomenon. Percolation theory has been used to describe the dependence of large-scale flow phenomena on heterogeneities found at the pore scale and should, therefore, be able to explain the water flow behaviour in hydrophobic soil. We show that the theory is valid, in general, for a hydrophilic soil into which a small but increasing fraction of highly hydrophobic grains is mixed. However, the application of percolation theory is limited by the complex interactions of matric potential and contact angle effects due to the introduction of hydrophobic particles.
Organic compounds at different depths in a sandy soil and their role in water repellency
Authors: Morley C. P. , Mainwaring K. A. , Doerr S. H. , Douglas P. , Llewellyn C. T. , Dekker L. W.
Published: May 2005

The causes of soil water repellency are still only poorly understood. It is generally assumed that hydrophobic organic compounds are responsible, but those concerned have not previously been identified by comparison between samples taken from a water repellent topsoil and the wettable subsoil. In this study we separated, characterised, and compared the organic compounds present at 4 different depths in a sandy soil under permanent grass cover that is water repellent in the upper 0.30 m but wettable below this.
Soil samples were extracted using a mixture of isopropanol and aqueous ammonia (7 : 3 v : v). Samples were wettable after extraction and re-application of the extract from each sample onto wettable sand induced water repellency. The chloroform-soluble portions of the extracts were analysed by gas chromatography and gas chromatography-mass spectrometry. The compounds identified at all soil depths included long-chain carboxylic acids (C16–C24), amides (C14–C24), alkanes (C25–C31), aldehydes or ketones (C25–C29), and more complex ring-containing structures. 1H and 13C nuclear magnetic resonance spectroscopy, and the carbon/hydrogen ratio as determined by microanalysis, confirmed the predominantly aliphatic character of the extracts.
Both wettable and water repellent samples contained hydrophobic compounds. The 3 water repellent samples contained far more organic material, although the amount extracted was not related to the degree of water repellency. Perhaps more importantly, they contained polar compounds of high relative molecular mass, which were almost absent from the wettable subsoil. It may be speculated that these are the compounds in this soil whose presence in significant amounts is necessary for water repellency to be exhibited.
STAT3 nuclear import is independent of tyrosine phosphorylation and mediated by importin-α3
Authors: Liu Ling , McBride Kevin M. , Reich Nancy C.
Published: May 2005

Signal transducer and activator of transcription (STAT)3 is a member of a family of DNA-binding factors that function to induce expression of responsive genes. STAT3 can act as an oncogene, and its function has been shown to be critical for cellular transformation by a number of oncogenic tyrosine kinases. The role of STAT3 as a DNA-binding transcription factor naturally depends on its ability to gain entrance to the nucleus. In this study, we provide evidence that STAT3 is distinct from previously characterized STAT molecules in that it dynamically shuttles between cytoplasmic and nuclear compartments and maintains prominent nuclear presence. Although tyrosine phosphorylation is required for STAT3 to bind to specific DNA target sites, nuclear import takes place constitutively and independently of tyrosine phosphorylation. We identify a region within the coiled-coil domain of the STAT3 molecule that is necessary for nuclear import and demonstrate that this region is critical for its recognition by specific import carrier importin-α3. RNA interference studies were used to verify the role and specificity of importin-α3 in STAT3 nuclear translocation. These results distinguish STAT3 cellular localization from other STAT molecules and identify a feature that may be targeted in the clinical intervention of STAT3-dependent neoplasia.
Hamilton's indicators of the force of selection
Authors: Baudisch Annette
Published: May 2005

To quantify the force of selection, Hamilton [Hamilton, W. D. (1966)J. Theor. Biol.12, 12–45] derived expressions for the change in fitness with respect to age-specific mutations. Hamilton's indicators are decreasing functions of age. He concluded that senescence is inevitable: survival and fertility decline with age. I show that alternative parameterizations of mutational effects lead to indicators that can increase with age. I then consider the case of deleterious mutations with age-specific effects. In this case, it is the balance between mutation and selection pressure that determines the equilibrium number of mutations in a population. In this balance, the effects of different parameterizations cancel out, but only to a linear approximation. I show that mutation accumulation has little impact at ages when this linear approximation holds. When mutation accumulation matters, nonlinear effects become important, and the parameterizations of mutational effects make a difference. The results also suggest that mutation accumulation may be relatively unimportant over most of the reproductive lifespan of any species.
The hypergraph regularity method and its applications
Authors: Rödl V. , Nagle B. , Skokan J. , Schacht M. , Kohayakawa Y.
Published: May 2005

Szemerédi's regularity lemma asserts that every graph can be decomposed into relatively few random-like subgraphs. This random-like behavior enables one to find and enumerate subgraphs of a given isomorphism type, yielding the so-called counting lemma for graphs. The combined application of these two lemmas is known as the regularity method for graphs and has proved useful in graph theory, combinatorial geometry, combinatorial number theory, and theoretical computer science. Here, we report on recent advances in the regularity method for
k
-uniform hypergraphs, for arbitrary
k
≥ 2. This method, purely combinatorial in nature, gives alternative proofs of density theorems originally due to E. Szemerédi, H. Furstenberg, and Y. Katznelson. Further results in extremal combinatorics also have been obtained with this approach. The two main components of the regularity method for
k
-uniform hypergraphs, the regularity lemma and the counting lemma, have been obtained recently: Rödl and Skokan (based on earlier work of Frankl and Rödl) generalized Szemerédi's regularity lemma to
k
-uniform hypergraphs, and Nagle, Rödl, and Schacht succeeded in proving a counting lemma accompanying the Rödl–Skokan hypergraph regularity lemma. The counting lemma is proved by reducing the counting problem to a simpler one previously investigated by Kohayakawa, Rödl, and Skokan. Similar results were obtained independently by W. T. Gowers, following a different approach.
MeSHer: identifying biological concepts in microarray assays based on PubMed references and MeSH terms
Authors: Djebbari Amira , Karamycheva Svetlana , Howe Eleanor , Quackenbush John
Published: May 2005

Summary: MeSHer uses a simple statistical approach to identify biological concepts in the form of Medical Subject Headings (MeSH terms) obtained from the PubMed database that are significantly overrepresented within the identified gene set relative to those associated with the overall collection of genes on the underlying DNA microarray platform. As a demonstration, we apply this approach to gene lists acquired from a published study of the effects of angiotensin II (Ang II) treatment on cardiac gene expression and demonstrate that this approach can aid in the interpretation of the resulting ‘significant’ gene set.

Availability: The software is available at http://www.tm4.org

Contact:  johnq@jimmy.harvard.edu

Supplementary information: Results from the analysis of significant genes from the published Ang II study.
New NTP analogs: the synthesis of 4′-thioUTP and 4′-thioCTP and their utility for SELEX
Authors: Kato Yuka , Minakawa Noriaki , Komatsu Yasuo , Kamiya Hiroyuki , Ogawa Naoki , Harashima Hideyoshi , Matsuda Akira
Published: May 2005

The synthesis of the triphosphates of 4′-thiouridine and 4′-thiocytidine, 4′-thioUTP (7; thioUTP) and 4′-thioCTP (8; thioCTP), and their utility for SELEX (systematic evolution of ligands by exponential enrichment) is described. The new nucleoside triphosphate (NTP) analogs 7 and 8 were prepared from appropriately protected 4′-thiouridine and -cytidine derivatives using the one-pot method reported by J. Ludwig and F. Eckstein [(1989) J. Org. Chem ., 54, 631–635]. Because SELEX requires both in vitro transcription and reverse transcription, we examined the ability of 7 and 8 for SELEX by focusing on the two steps. Incorporation of 7 and 8 by T7 RNA polymerase to give 4′-thioRNA (thioRNA) proceeded well and was superior to those of the two sets of frequently used modified NTP analogs for SELEX (2′-NH 2 dUTP and 2′-NH 2 dCTP; 2′-FdUTP and 2′-FdCTP), when an adequate leader sequence of DNA template was selected. We revealed that a leader sequence of about +15 of DNA template is important for the effective incorporation of modified NTP analogs by T7 RNA polymerase. In addition, reverse transcription of the resulting thioRNA into the complementary DNA in the presence of 2′-deoxynucleoside triphosphates (dNTPs) also proceeded smoothly and precisely. The stability of the thioRNA toward RNase A was 50 times greater than that of the corresponding natural RNA. With these successful results in hand, we attempted the selection of thioRNA aptamers to human α-thrombin using thioUTP and thioCTP, and found a thioRNA aptamer with high binding affinity ( Kd = 4.7 nM).
Composite genome map and recombination parameters derived from three archetypal lineages of
Toxoplasma gondii
Authors: Khan Asis , Taylor Sonya , Su Chunlei , Mackey Aaron J. , Boyle Jon , Cole Robert , Glover Darius , Tang Keliang , Paulsen Ian T. , Berriman Matt , Boothroyd John C. , Pfefferkorn Elmer R. , Dubey J. P. , Ajioka James W. , Roos David S. , Wootton John C. , Sibley L. David
Published: May 2005

Toxoplasma gondii is a highly successful protozoan parasite in the phylum Apicomplexa, which contains numerous animal and human pathogens. T.gondii is amenable to cellular, biochemical, molecular and genetic studies, making it a model for the biology of this important group of parasites. To facilitate forward genetic analysis, we have developed a high-resolution genetic linkage map for T.gondii . The genetic map was used to assemble the scaffolds from a 10X shotgun whole genome sequence, thus defining 14 chromosomes with markers spaced at ∼300 kb intervals across the genome. Fourteen chromosomes were identified comprising a total genetic size of ∼592 cM and an average map unit of ∼104 kb/cM. Analysis of the genetic parameters in T.gondii revealed a high frequency of closely adjacent, apparent double crossover events that may represent gene conversions. In addition, we detected large regions of genetic homogeneity among the archetypal clonal lineages, reflecting the relatively few genetic outbreeding events that have occurred since their recent origin. Despite these unusual features, linkage analysis proved to be effective in mapping the loci determining several drug resistances. The resulting genome map provides a framework for analysis of complex traits such as virulence and transmission, and for comparative population genetic studies.
A versatile reducible polycation-based system for efficient delivery of a broad range of nucleic acids
Authors: Read Martin L. , Singh Surjeet , Ahmed Zubair , Stevenson Mark , Briggs Simon S. , Oupicky David , Barrett Lee B. , Spice Rachel , Kendall Mark , Berry Martin , Preece Jon A. , Logan Ann , Seymour Leonard W.
Published: May 2005

Synthetic vectors based on reducible polycations consisting of histidine and polylysine residues (HIS RPCs) were evaluated for their ability to deliver nucleic acids. Initial experiments showed that RPC-based vectors with at least 70% histidine content mediated efficient levels of gene transfer without requirement for the endosomolytic agent chloroquine. Significant gene transfer was observed in a range of cell types achieving up to a 5-fold increase in the percentage of transfected cells compared to 25 kDa PEI, a gold standard synthetic vector. In contrast to 25 kDa PEI, HIS RPCs also mediated efficient transfer of other nucleic acids, including mRNA encoding green fluorescent protein in PC-3 cells and siRNA directed against the neurotrophin receptor p75 NTR in post-mitotic cultures of rat dorsal root ganglion cell neurons. Experiments to elevate intracellular glutathione and linear profiling of cell images captured by multiphoton fluorescent microscopy highlighted that parameters such as the molecular weight and rate of cleavage of HIS RPCs were important factors in determining transfection activity. Altogether, these results demonstrate that HIS RPCs represent a novel and versatile type of vector that can be used for efficient cytoplasmic delivery of a broad range of nucleic acids. This should enable different or a combination of therapeutic strategies to be evaluated using a single type of polycation-based vector.
Non-standard finite-difference methods for vibro-impact problems
Authors: Dumont Yves , Lubuma Jean M.-S
Published: May 2005

Impact oscillators are non-smooth systems with such complex behaviours that their numerical treatment by traditional methods is not always successful. We design non-standard finite-difference schemes in which the intrinsic qualitative parameters of the system—the restitution coefficient, the oscillation frequency and the structure of the nonlinear terms—are suitably incorporated. The schemes obtained are unconditionally stable and replicate a number of important physical properties of the involved oscillator system such as the conservation of energy between two consecutive impact times. Numerical examples, including the Duffing oscillator that develops a chaotic behaviour for some positions of the obstacle, are presented. It is observed that the cpu times of computation are of the same order for both the standard and the non-standard schemes.
A starfish with three-dimensionally preserved soft parts from the Silurian of England
Authors: Sutton M.D , Briggs D.E.G , Siveter David J , Siveter Derek J , Gladwell D.J
Published: May 2005

Palaeozoic asteroids represent a stem-group to the monophyletic post-Palaeozoic Neoasteroidea, but many aspects of their anatomy are poorly known. Using serial grinding and computer reconstruction, we describe fully articulated Silurian (
ca
425 Myr) specimens from the Herefordshire Lagerstätte, preserved in three dimensions complete with soft tissues. The material belongs to a species of
Bdellacoma
, a genus previously assigned to the ophiuroids, but has characters that suggest an asteroid affinity. These include a pyloric system in the gut, and the presence of large bivalved pedicellariae, the latter originally described under the name
Bursulella
from isolated valves. Ampullae are external and occur within podial basins; the radial canal is also external. Podia are elongate and lack terminal suckers. The peristome is large relative to the mouth. Aspects of the morphology are comparable to that of the extant Paxillosida, supporting phylogenetic schemes that place this order at the base of the asteroid crown group.
Neighbour-nets portray the Chinese dialect continuum and the linguistic legacy of China's demic history
Authors: Hamed Mahé Ben
Published: May 2005

As with species studied by evolutionary biologists, languages are evolving entities. They can evolve in tree-like patterns, possibly blurred by borrowing, but they can also develop in non-tree-like schemes. For instance, diglossia, as in the case of Chinese, can counterbalance the hierarchical pattern expected from differentiation by internal change associated with isolation by distance of speech communities. Using two lexical datasets, either the basic lexicon supposedly more immune to borrowing or a representative sample of the whole lexicon, we investigate the development pattern of Chinese dialects using a neighbour-net approach, which is an unprejudiced technique for representing object relationships. The resulting graphs are consistent with a dialect continuum shaped by counterbalanced effects of homogenizing diglossia and borrowing versus differentiating spread of speech communities. Historical events and linguistic claims can be mapped on these graphs.
Socially transmitted mate preferences in a monogamous bird: a non-genetic mechanism of sexual selection
Authors: Swaddle John P , Cathey Mark G , Correll Maureen , Hodkinson Brendan P
Published: May 2005

There is increasing evidence that animals can acquire mate preferences through the use of public information, notably by observing (and copying) the mate preferences of others in the population. If females acquire preferences through social mechanisms, sexual selection could act very rapidly to spread the preference and drive elaboration of the preferred trait(s). Although there are reports of ‘mate-choice copying’ in polygynous species, there is no clear evidence for this process in monogamous species. Here, we investigated whether adult female zebra finchesTaeniopygia guttatacan socially acquire sexual preferences for individual males and, in a separate study, for a generalized trait (coloured leg bands) of males. In both studies, test females observed males in two simultaneous conditions: a (‘chosen’) mixed-sex situation in which a male was paired with a (model) female, and a (‘unchosen’) same-sex situation in which a male was paired with another male. In the first experiment, after two weeks of females observing males, test females significantly preferred individual males who had been paired with another female (i.e. chosen males). In the second experiment, test females significantly preferred novel males that were wearing the same leg band colour as the apparently chosen males. Our findings are consistent with the conclusion that female zebra finches' mate preferences are altered by public information. Our study implies that mate preferences can spread rapidly through populations by social mechanisms, affecting the strength of sexual selection in a monogamous species.
Blow-up and control of marginally separated boundary layers
Authors: Braun Stefan , Kluwick Alfred
Published: May 2005

Interactive solutions for steady two-dimensional laminar marginally separated boundary layers are known to exist up to a critical value
Γ
c
of the controlling parameter (e.g. the angle of attack of a slender airfoil)
Γ
only. Here, we investigate three-dimensional unsteady perturbations of such boundary layers, assuming that the basic flow is almost critical, i.e. in the limit
Γ
c
−
Γ
→0. It is then shown that the interactive equations governing such perturbations simplify significantly, allowing, among others, a systematic study of the blow-up phenomenon observed in earlier investigations and the optimization of devices used in boundary‐layer control.
Seasonal change in offspring sex and size in Dawson's burrowing bees (Amegilla dawsoni) (Hymenoptera: Anthophorini)
Authors: Alcock John , Simmons Leigh W. , Beveridge Maxine
Published: May 2005

Abstract.  1. Nesting females of Dawson's burrowing bees, Amegilla dawsoni, produce a large size class of offspring, which includes daughters and major sons, and a small size class, which consists entirely of minor sons averaging half the weight of their larger siblings. Female allocation patterns change over the flight season such that the initial pattern of producing daughters shifts toward the production of both daughters and major sons in the middle of the season, and then the production of primarily minor sons in the latter part of the nesting season.

2. In Dawson's burrowing bees, this pattern is correlated with declines in pollen and nectar availability as the nesting season progresses as well as a heightened risk of dying before the final brood cell is completed. Here, the relation between these factors and the provisioning tactics of nesting Dawson's burrowing bees is discussed.
Oviposition habitat selection for a predator refuge and food source in a mosquito
Authors: Bond J. Guillermo , Arredondo‐Jiménez Juan I. , Rodríguez Mario H. , Quiroz‐Martínez Humberto , Williams Trevor
Published: May 2005

Abstract.  1. The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles pseudopunctipennis and the consequences of oviposition decisions on the diet, development, body size, and survival of offspring were examined.

2. A natural population of An. pseudopunctipennis in Chiapas, Mexico, oviposited almost exclusively in containers with filamentous algae. Algae represented 47% of the gut contents of mosquito larvae sampled from the natural population. Mosquito larvae fed on an exclusive diet of algae developed as quickly and achieved the same adult body size (wing length) as their conspecifics fed on a standard laboratory diet.

3. Multiple regression of survival of mosquito larvae on percentage surface area cover of algae (0–99%) and the density of predatory fish (zero to four fish per container) was best described by a second‐order polynomial model. Increasing fish densities resulted in a reduction in mosquito survival in all algal treatments. The highest incidence of survival was observed at intermediate (66%) algal cover in all treatments.

4. The presence of fish significantly extended larval development times whereas algal cover had no significant effect. The presence of fish resulted in emergence of smaller adults due to reduced feeding opportunities and predator avoidance behaviour. Algal cover also affected mosquito wing length but differently at each fish density.

5. Oviposition habitat selection improves survival in the presence of predators and feeding opportunities for An. pseudopunctipennis larvae.
Effect of low rainfall and browsing by large herbivores on an enclosed savannah habitat in Kenya
Authors: Birkett Alan , Stevens‐Wood Barry
Published: May 2005

Savannah ecosystems in East Africa are rarely stable and can experience rapid local changes from dense woodlands to open plains. In this 3‐year study there was a reduction of 16.3% in a height‐stratified sample of nearly 1000 individually marked Acacia drepanolobium trees. The study was carried out in an enclosed fire‐free wooded grassland habitat in the Laikipia region of Kenya. The trees were monitored from 1998 to 2001, a period that included 12 months when rainfall was 60% below average. Elephants were responsible for the loss of 40% of the trees, black rhinos 33% and 27% died from the effects of the drought. Low rainfall was correlated with increased damage as elephants switched diet from grass to trees. Heavy browsing by giraffes reduced tree growth rates and increased their susceptibility to drought. Hence the combination of low rainfall and heavy browsing by elephants, black rhinos and giraffes led to the rapid tree loss. These findings have implications for research into the causes of instability in savannah ecosystems and the management of enclosed reserves.
On the presence and distribution of olive viruses in Lebanon
Authors: Fadel C. , Digiaro M. , Choueiri E. , El Beaino T. , Saponari M. , Savino V. , Martelli G. P.
Published: May 2005

A survey for viruses was carried out in 2003 in the main olive‐growing areas of Lebanon (South Lebanon, North Lebanon, Mount Lebanon and Bekaa). A total of 300 samples was collected in 31 different locations in 76 different commercial orchards and checked by RT‐PCR for the presence of Arabis mosaic virus (ArMV), Cherry leaf roll virus (CLRV), Strawberry latent ringspot virus (SLRV), Olive latent virus 1 (OLV‐1) and Olive leaf yellowing‐associated virus (OLYaV), using virus‐specific primers reported in the literature. About one third (31%) of the trees were infected. In particular, the closterovirus OLYaV was the most widespread, as it was detected in 23.7% of the samples, followed by the necrovirus OLV‐1 (8.3%), the two nepoviruses CLRV (2%) and ArMV (0.3%), and the sadwavirus SLRV (0.3%). A high variability was detected in the HSP70 gene of Lebanese and Italian OLYaV isolates, for at least nine different patterns were obtained when this genomic region was subjected to single‐strand conformation polymorphism (SSCP) analysis.
Role and development of invertebrate collections in quality of identification for quarantine pests*
Authors: Hockland S.
Published: May 2005

Preserved collections of invertebrates are essential for the identification of species and research, and are thus a prerequisite for accredited identification procedures. They are particularly important for phytosanitary taxonomists, where decisions on identification may have serious financial consequences. The use of published descriptions and keys alone is not sufficient without simultaneous reference to comprehensive collections of validated specimens. Despite their importance, holders of collections generally have insufficient resource for conservation and curation of their material, leading to the possibility that unique material and data are lost. Taxonomists are also becoming fewer in number generally, with some invertebrate subject groups receiving little or no attention. In consequence, networking between taxonomists and other phytosanitary staff involved in identification should be encouraged. Conservation and curation procedures should be harmonized. It is possible that some collections should merge to avoid the loss of invaluable reference material. Progress in information technology should create interest in cataloguing material and making it widely available on the Internet. Such cataloguing should include digital images which may assist those without access to actual collections.
Development of an EU protocol for the detection and diagnosis of Potato spindle tuber pospiviroid*
Authors: Jeffries C. , James C.
Published: May 2005

The work described here formed part of the EU SMT DIAGPRO project, to develop diagnostic protocols for 18 regulated pests. The Potato spindle tuber pospiviroid (PSTVd) protocol was developed primarily for testing in vitro‐ and glasshouse‐grown potato plants for the purposes of post‐entry quarantine and the production of pathogen‐tested nuclear stock. After a performance audit of methods used by 12 laboratories in Europe and America by ring testing, four methods were chosen for multilaboratory validation. For most laboratories, the detection limits were 10–20 mg of PSTVd‐infective tissue for R‐PAGE; 0.25–0.5 mg for DIG‐probe; 0.062 mg for RT‐PCR; and 0.0155 mg for TaqMan (this was the lowest weight of infective tissue tested). Some laboratories were able to extend the detection limit to 0.0155 mg for DIG‐probe and RT‐PCR. The DIG‐probe and R‐PAGE are recommended as primary detection methods, with confirmation of viroid presence by any of the four validated detection methods. Specific diagnosis requires the viroid to be sequenced. Other methods may be used for primary detection, providing that they preferably detect all PSTVd isolates and other Pospiviroids that have the potential to infect potato, and detect viroid in at least 1/10 of the tissue weight normally tested per plant.
Development of RT‐PCR assays using fluorogenic‐3′ minor groove binder DNA probes for detection of fruit tree viruses*
Authors: Roussel S. , Kummert J. , Salmon M. , Dutrecq O. , Jijakli M. H.
Published: May 2005

In phytosanitary certification, there is currently a need for the development of reliable, sensitive and rapid tests for the routine detection of Ilarviruses and latent viruses from fruit trees during the dormant season. We have developed real‐time RT‐PCR assays that allow the reliable detection of Prunus necrotic ringspot ilarvirus, Apple chlorotic leafspot trichovirus and Apple stem pitting virus in bark tissues of dormant wood. These assays are well adapted for the routine detection of these three viruses because they eliminate one risk of contamination by performing the whole test in a single closed tube.
Impact of molecular phylogenetics on the taxonomy and diagnostics of fungi*
Authors: Crous P. W.
Published: May 2005

Most phytosanitary inspections rely on a visual ‘disease‐free’ inspection, and the question is raised whether this is sufficient, given the fact that plant pathogenic fungi may enter countries as endophytes, or latent pathogens in apparently healthy tissue. Inspectors mostly deal with lists of names of fungal species, but many pathogens are in fact species complexes, and pest lists rarely remain up to date with respect to new systematic treatments. Pathogens may also introduce new genetic diversity or mating types, which could be as devastating as the introduction of a new pathogen. It is therefore proposed that an international initiative should be funded to ensure that systematic support, accurate nomenclature, genetic material and genomic data are available to assist NPPOs in their task.
CABI/EPPO distribution maps of plant pests and plant diseases and their important role in plant quarantine
Authors: Pasiecznik N. M. , Smith I. M. , Watson G. W. , Brunt A. A. , Ritchie B. , Charles L. M. F.
Published: May 2005

Never before has the need for accurate distribution data for plant pests been so important. CAB International (CABI) and EPPO are international organizations with a long history and strong involvement in collating and disseminating information on the global distribution of plant pests. Distribution Maps of Plant Pests and Distribution Maps of Plant Diseases, first published in 1951 and 1942, respectively, are respected, referenced sources of such data, expertly compiled and validated and used by plant health organizations around the world. They have been joint CABI/EPPO publications since 1997, and provide an essential complement to expanding knowledge on plant pest distribution. The Distribution Maps continue to be the most authoritative sources of information on the presence and extent of specific plant pests, sourced from the 4.5 million records in CAB Abstracts as a basis and numerous other sources. They also feed directly into CABI's Crop Protection Compendium (CPC) and EPPO's Plant Quarantine Data Retrieval System (PQR) databases. Their history, compilation and value are discussed.
The dynamics of landscape change and snow geese in mid‐continent North America
Authors: Abraham Kenneth F. , Jefferies Robert L. , Alisauskas Ray T.
Published: May 2005

The Mid‐Continent Population of the lesser snow goose, which breeds in the eastern and central Canadian Arctic and sub‐Arctic, and winters in the southern United States and northern Mexico has increased 5–7% annually from the late 1960s to the mid‐1990s, largely because of increased survival in response to an agricultural food subsidy. The rise in numbers complements the increased use of nitrogen fertilizers and a corresponding rise in yields of rice, corn, and wheat along the flyways and on the wintering grounds. In sub‐Arctic migration areas and at Arctic breeding colonies, foraging by high numbers of birds has led to loss of coastal vegetation, adverse changes in soil properties and the establishment of an alternative stable state of exposed sediment, which can be detected with LANDSAT imagery. At a local scale, gosling growth, size and survival decreased in affected areas and other taxa have been adversely affected. The food subsidy on wintering and migration areas appears insufficient to meet reproductive demands as foraging in spring continues to occur on southern Hudson Bay staging and nesting areas. The recent introduction of liberal hunting regulations may reduce population size in the near term, but the revegetation of these coastal ecosystems will take decades to achieve. The present pattern of vegetation loss in these Arctic coastal systems is likely to continue in the forseeable future.
Climate change and the fate of cereal aphids in Southern Britain
Authors: Newman J. A.
Published: May 2005

Climate change will drive dramatic changes in the abundance and distribution of species. Assessing the impacts of climate change on our agricultural systems is essential for mitigation planning. Here, I combine projections from the UK Hadley Centre's HadRM03 climate change model for Southern Britain with a general mechanistic model of the interaction between climate, temperate grass physiology and cereal aphid population dynamics. Aphids are one of the largest and most important groups of crop pests and disease vectors worldwide but particularly in temperate regions. The model predicts an increasingly dramatic decline in cereal aphid abundance from the 1961 to 1990 baseline with increasing CO2 emissions: low emissions=−5%, medium low=−12%, medium high=−61%, and high=−92%. Of the six climate variables used in the model, changes in temperature and rainfall were the most important across all emissions scenarios and, counter‐intuitively, the direct impact of elevated CO2 actually declines as emissions increase. The results suggest that the pest status of cereal aphids in Southern Britain will significantly decline by the end of this century.
Diurnal, seasonal and annual variation in the net ecosystem CO2 exchange of a desert shrub community (Sarcocaulescent) in Baja California, Mexico
Authors: Hastings Steven J. , Oechel Walter C. , Muhlia‐Melo Arturo
Published: May 2005

Estimates of net ecosystem exchange (NEE) of CO2 have been measured on a variety of ecosystems world wide including grasslands, savannahs, boreal, pine, deciduous, Mediterranean and tropical rain forests as well as arctic tundra. While there have been numerous comparisons between net primary productivity of arid and semiarid grasslands and shrublands, notably lacking are estimates of NEE with a few exceptions. The objective of this study was to characterize the seasonal and annual carbon flux of a desert shrub ecosystem using the eddy covariance technique to determine the sensitivity of the system to the timing and varying amounts of precipitation. Measurements began in July of 2001, a year with 339 mm of rainfall, considerably above the long‐term average of 174 mm and preceded by 2 years of below average rainfall (50–62 mm). Over the 2 complete years of measurements, precipitation was 147 and 197 mm in 2002 and 2003, respectively. In all years, the majority of the precipitation fell between August and September. The site was a sink of −39 g C m−2 yr−1 in 2002 with a relatively strong uptake in the early part of the year and reduced uptake after the suboptimal rainfall in September. This contrasts with 2003 when the ecosystem took up −52 g C m−2 yr−1 concentrated in the fall after significant rain in August and September. Likely, extremely low rainfall years would result in a carbon loss while a strengthening of the typical winter secondary peak in precipitation (notably absent in the 2 years of measurements) may extend uptake into the spring resulting in more carbon accumulation. The system appears to be buffered against variations in annual rainfall attributed to water storage in the stems and roots.
Aboveground Forest Biomass and the Global Carbon Balance
Authors: Houghton R. A.
Published: May 2005

The long‐term net flux of carbon between terrestrial ecosystems and the atmosphere has been dominated by two factors: changes in the area of forests and per hectare changes in forest biomass resulting from management and regrowth. While these factors are reasonably well documented in countries of the northern mid‐latitudes as a result of systematic forest inventories, they are uncertain in the tropics. Recent estimates of carbon emissions from tropical deforestation have focused on the uncertainty in rates of deforestation. By using the same data for biomass, however, these studies have underestimated the total uncertainty of tropical emissions and may have biased the estimates. In particular, regional and country‐specific estimates of forest biomass reported by three successive assessments of tropical forest resources by the FAO indicate systematic changes in biomass that have not been taken into account in recent estimates of tropical carbon emissions. The ‘changes’ more likely represent improved information than real on‐the‐ground changes in carbon storage. In either case, however, the data have a significant effect on current estimates of carbon emissions from the tropics and, hence, on understanding the global carbon balance.
Leaf litter production and decomposition in a poplar short‐rotation coppice exposed to free air CO2 enrichment (POPFACE)
Authors: Cotrufo M. Francesca , De Angelis Paolo , Polle Andrea
Published: May 2005

The capacity of forest ecosystems to sequester C in the soil relies on the net balance between litter production above, as well as, below ground, and decomposition processes. Nitrogen mineralization and its availability for plant growth and microbial activity often control the speed of both processes. Litter production, decomposition and N mineralization are strongly interdependent. Thus, their responses to global environmental changes (i.e. elevated CO2, climate, N deposition, etc.) cannot be fully understood if they are studied in isolation. In the present experiment, we investigated litter fall, litter decomposition and N dynamics in decomposing litter of three Populus spp., in the second and third growing season of a short rotation coppice under FACE. Elevated CO2 did not affect annual litter production but slightly retarded litter fall in the third growing season. In all species, elevated CO2 lowered N concentration, resulting in a reduction of N input to the soil via litter fall, but did not affect lignin concentrations. Litter decomposition was studied in bags incubated in situ both in control and FACE plots. Litter lost between 15% and 18% of the original mass during the eight months of field incubation. On average, litter produced under elevated CO2 attained higher residual mass than control litter. On the other end, when litter was incubated in FACE plots it exhibited higher decay rates. These responses were strongly species‐specific. All litter increased their N content during decomposition, indicating immobilization of N from external sources. Independent of the initial quality, litter incubated on FACE soils immobilized less N, possibly as a result of lower N availability in the soil. Indeed, our results refer to a short‐term decomposition experiment. However, according to a longer‐term model extrapolation of our results, we anticipate that in Mediterranean climate, under elevated atmospheric CO2, soil organic C pool of forest ecosystems may initially display faster turnover, but soil N availability will eventually limit the process.
The North Atlantic Oscillation and regional phenology prediction over Europe
Authors: Cook Benjamin I. , Smith Thomas M. , Mann Michael E.
Published: May 2005

We present an integrated modeling study designed to investigate changes in ecosystem level phenology over Europe associated with changes in climate pattern, by the North Atlantic Oscillation (NAO). We derived onset dates from processed NDVI data sets and used growing degree day (GDD) summations from the NCEP re‐analysis to calibrate and validate a phenology model to predict the onset of the growing season over Europe. In a cross‐validation hindcast, the model (PHENOM) is able to explain 63% of the variance in onset date for grid cells containing at least 50% mixed and boreal forest. Using a model developed from previous work we performed climate change scenarios, generating synthetic temperature and GDD distributions under a hypothetically increasing NAO. These new distributions were used to drive PHENOM and project changes in the timing of onset for forested cells over Europe. Results from the climate change scenarios indicate that, if the current trend in the NAO continues, there is the potential for a continued advance to the start of the growing season by as much as 13 days in some areas.
Non‐myeloablative allogenic peripheral blood stem cell transplantation in a patient with refractory osteosarcoma
Authors: Kounami Shinji , Nakayama Keiko , Yoshiyama Megumi , Yoshimasu Tetsu , Aoyagi Noriyuki , Yoshikawa Norishige
Published: May 2005

Abstract:  The prognosis of patients with relapsed osteosarcoma is dismal despite the use of intensive chemotherapy. We describe a patient with refractory osteosarcoma who underwent non‐myeloablative peripheral blood stem cell transplantation (PBSCT) from an human leukocyte antigen (HLA)‐identical sibling during a third complete remission. The patient suffered pulmonary relapse after the transplantation. Cyclosporin A withdrawal induced a graft‐vs.‐osteosarcoma effect and graft‐vs.‐host disease, but eventually the tumor progressed. Although our experience in this case suggested the presence of a graft‐vs.‐osteosarcoma effect during non‐myeloablative allogenic PBSCT, this strategy might have limited value for refractory osteosarcoma with rapid growth kinetics.