bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereoselective biotransformation of ketamine in equine liver and lung microsomes
Authors: SCHMITZ A. , PORTIER C. J. , THORMANN W. , THEURILLAT R. , MEVISSEN M. 
Published: June 2008

Stereoselectivity has to be considered for pharmacodynamic and pharmacokinetic features of ketamine. Stereoselective biotransformation of ketamine was investigated in equine microsomesin vitro.Concentration curves were constructed over time, and enzyme activity was determined for different substrate concentrations using equine liver and lung microsomes. The concentrations of R/S‐ketamine and R/S‐norketamine were determined by enantioselective capillary electrophoresis. A two‐phase model based on Hill kinetics was used to analyze the biotransformation of R/S‐ketamine into R/S‐norketamine and, in a second step, into R/S‐downstream metabolites.In liver and lung microsomes, levels of R‐ketamine exceeded those of S‐ketamine at all time points and S‐norketamine exceeded R‐norketamine at time points below the maximum concentration. In liver and lung microsomes, significant differences in the enzyme velocity (Vmax) were observed between S‐ and R‐norketamine formation and betweenVmaxof S‐norketamine formation when S‐ketamine was compared to S‐ketamine of the racemate.Our investigations in microsomal reactionsin vitrosuggest that stereoselective ketamine biotransformation in horses occurs in the liver and the lung with a slower elimination of S‐ketamine in the presence of R‐ketamine. Scaling of thein vitroparameters to liver and lung organ clearances provided an excellent fit with previously publishedin vivodata and confirmed a lung first‐pass effect.
Female multiple mating in wild and laboratory populations of the two‐spot ladybird, Adalia bipunctata
Authors: HADDRILL PENELOPE R. , SHUKER DAVID M. , AMOS WILLIAM , MAJERUS MICHAEL E. N. , MAYES SEAN 
Published: June 2008

AbstractFemale mating rate is an important variable for understanding the role of females in the evolution of mating systems. Polyandry influences patterns of sexual selection and has implications for sexual conflict over mating, as well as for wider issues such as patterns of gene flow and levels of genetic diversity. Despite this, remarkably few studies of insects have provided detailed estimates of polyandry in the wild. Here we combine behavioural and molecular genetic data to assess female mating frequency in wild populations of the two‐spot ladybird, Adalia bipunctata (Coleoptera: Coccinellidae). We also explore patterns of sperm use in a controlled laboratory environment to examine how sperm from multiple males is used over time by females, to link mating with fertilization. We confirm that females are highly polyandrous in the wild, both in terms of population mating rates (~20% of the population found in copula at any given time) and the number of males siring offspring in a single clutch (three to four males, on average). These patterns are consistent across two study populations. Patterns of sperm use in the laboratory show that the number of mates does not exceed the number of fathers, suggesting that females have little postcopulatory influence on paternity. Instead, longer copulations result in higher paternity for males, probably due to the transfer of larger numbers of sperm in multiple spermatophores. Our results emphasize the importance of combining field and laboratory data to explore mating rates in the wild.
The history of Seasonally Dry Tropical Forests in eastern South America: inferences from the genetic structure of the tree Astronium urundeuva (Anacardiaceae)
Authors: CAETANO S. , PRADO D. , PENNINGTON R. T. , BECK S. , OLIVEIRA‐FILHO A. , SPICHIGER R. , NACIRI Y. 
Published: June 2008

AbstractToday, the Seasonally Dry Tropical Forests (SDTF) of eastern South America occur as large, well‐defined nuclei (e.g. Caatinga in the northeast) and as smaller enclaves within other vegetations (e.g. Cerrado and Chaco). In order to infer the way the present SDTF distribution was attained, the genetic structure of Astronium urundeuva, a tree confined to SDTF, was assessed using two chloroplast spacers and nine microsatellite loci. Five haplotypes were identified, whose distribution was spatially structured. The distribution of the two most common and divergent haplotypes suggested former vicariance and progressive divergence due to isolation. More recent range expansions of these two lineages subsequently occurred, leading to a secondary contact at the southern limit of the Caatinga SDTF nucleus. The multilocus‐Bayesian approach using microsatellites consistently identified three groups of populations (Northeast, Central and Southwest). Isolation by distance was found in Northeast and Southwest groups whereas admixture was detected in the Central group, located at the transition between Caatinga and Cerrado domains. All together, the results support the existence of range expansions and secondary contact in the Central group. This study provides arguments that favour the existence of a previously more continuous formation of SDTF in eastern South America.
Population transcriptomics of life‐history variation in the genusSalmo
Authors: GIGER THOMAS , EXCOFFIER LAURENT , AMSTUTZ URSULA , DAY PHILIP J. R. , CHAMPIGNEULLE ALEXIS , HANSEN MICHAEL M. , KELSO JANET , LARGIADÈR CARLO R. 
Published: June 2008

AbstractIn this study, we demonstrate the power of applying complementary DNA (cDNA) microarray technology to identifying candidate loci that exhibit subtle differences in expression levels associated with a complex trait in natural populations of a nonmodel organism. Using a highly replicated experimental design involving 180 cDNA microarray experiments, we measured gene‐expression levels from 1098 transcript probes in 90 individuals originating from six brown trout (Salmo trutta) and one Atlantic salmon (Salmo salar) population, which follow either a migratory or a sedentary life history. We identified several candidate genes associated with preparatory adaptations to different life histories in salmonids, including genes encoding for transaldolase 1, constitutive heat‐shock protein HSC70‐1 and endozepine. Some of these genes clustered into functional groups, providing insight into the physiological pathways potentially involved in the expression of life‐history related phenotypic differences. Such differences included the down‐regulation of genes involved in the respiratory system of future migratory individuals. In addition, we used linear discriminant analysis to identify a set of 12 genes that correctly classified immature individuals as migratory or sedentary with high accuracy. Using the expression levels of these 12 genes, 17 out of 18 individuals used for cross‐validation were correctly assigned to their respective life‐history phenotype. Finally, we found various candidate genes associated with physiological changes that are likely to be involved in preadaptations to seawater in anadromous populations of the genusSalmo, one of which was identified to encode for nucleophosmin 1. Our findings thus provide new molecular insights into salmonid life‐history variation, opening new perspectives in the study of this complex trait.
Transgenic salt‐tolerant sugar beet (Beta vulgaris L.) constitutively expressing an Arabidopsis thaliana vacuolar Na+/H+ antiporter gene, AtNHX3, accumulates more soluble sugar but less salt in storage roots
Authors: LIU HUA , WANG QIUQING , YU MENGMENG , ZHANG YANYAN , WU YINGBAO , ZHANG HONGXIA 
Published: June 2008

ABSTRACTIn Arabidopsis thaliana, six vacuolar Na+/H+ antiporters (AtNHX1‐6) were identified. Among them, AtNHX1, 2 and 5 are functional Na+/H+ antiporters with the most abundant expression levels in seedling shoots and roots. However, the expression of AtNHX3 in Arabidopsis can only be detected by RT‐PCR, and its physiological function still remains unclear. In this work, we demonstrate that constitutive expression of AtNHX3 in sugar beet (Beta vulgaris L.) conferred augmented resistance to high salinity on transgenic plants. In the presence of 300 or 500 mm NaCl, transgenic plants showed very high potassium accumulation in the roots and storage roots. Furthermore, the transcripts of sucrose phosphate synthase (SPS), sucrose synthase (SS) and cell wall sucrose invertase (SI) genes were maintained in transgenic plants. The accumulation of soluble sugar in the storage roots of transgenic plants grown under high salt stress condition was also higher. Our results implicate that AtNHX3 is also a functional antiporter responsible for salt tolerance by mediating K+/H+ exchange in higher plants. The salt accumulation in leaves but not in the storage roots, and the increased yield of storage roots with enhanced constituent soluble sugar contents under salt stress condition demonstrate a great potential use of this gene in improving the quality and yield of crop plants.
Drought‐induced changes in anthesis‐silking interval are related to silk expansion: a spatio‐temporal growth analysis in maize plants subjected to soil water deficit
Authors: FUAD‐HASSAN AVAN , TARDIEU FRANÇOIS , TURC OLIVIER 
Published: June 2008

ABSTRACTThe growth and emergence of maize silks has a considerable importance in yield determination under drought conditions. Spatial and temporal patterns of the rates of tissue expansion and of cell division were characterized in silks of plants subjected to different soil water potentials. In all cases, silk development consisted of four phases: (1) cell division and tissue expansion occurred together uniformly all along the silk; (2) cell division progressively ceased from tip to base, while expansion remained spatially uniform including during the phase (3) after the cessation of cell division; and (4) as the silk emerged from the husks, expansion ceased in the emerged portion, probably because of direct evaporative demand, while the relative growth rate progressively decreased in the enclosed part. The rates of tissue expansion and cell division were reduced with water deficit, resulting in delayed silk emergence. The duration of cell division was not affected, and in all cases, the end of cell division in the silk coincided with anther dehiscence. The duration of phase 3, between the end of cell division and the arrest of cell growth in silk apex, considerably increased with water deficit. It corresponded to the anthesis‐silking interval used by breeders to characterize the response of cultivars to stress.
Rhododendron catawbiense plasma membrane intrinsic proteins are aquaporins, and their over‐expression compromises constitutive freezing tolerance and cold acclimation ability of transgenic Arabidopsis plants
Authors: PENG YANHUI , ARORA RAJEEV , LI GUOWEI , WANG XIANG , FESSEHAIE ANANIA 
Published: June 2008

ABSTRACTExtracellular freezing results in cellular dehydration caused by water efflux, which is likely regulated by aquaporins (AQPs). In a seasonal cold acclimation (CA) study of Rhododendron catawbiense, two AQP cDNAs, RcPIP2;1 and RcPIP2;2, were down‐regulated as the leaf freezing tolerance (FT) increased from −7 to ∼−50 °C. We hypothesized this down‐regulation to be an adaptive component of CA process allowing cells to resist freeze‐induced dehydration. Here, we characterize full‐length cDNAs of the two Rhododendron PIPs, and demonstrate that RcPIP2s have water channel activity. Moreover, RcPIP2s were over‐expressed in Arabidopsis, and FT of transgenic plants was compared with that of wild‐type (WT) controls. Data indicated a significantly lower constitutive FT and CA ability of RcPIP2‐OXP plants (compared with WT) due, presumably, to their lower ability to resist freeze desiccation. A relatively higher dehydration rate of RcPIP2‐OXP leaves (than WT) supports this notion. Phenotypic and microscopic observations revealed bigger leaf size and mesophyll cells of RcPIP2‐OXP plants than WT. It is proposed that lower FT of transgenic plants may be associated with their leaf cells' propensity to greater mechanical stress, that is, volume strain per unit surface, during freeze–thaw‐induced contraction or expansion. Additionally, greater freeze injury in RcPIP2‐OXP plants could also be attributed to their susceptibility to potentially faster rehydration (than WT) during a thaw.
Dietary β‐hydroxy‐β‐methylbutyrate supplementation influences performance differently after immunization in broiler chickens
Authors: Buyse J. , Swennen Q. , Vandemaele F. , Klasing K. C. , Niewold T. A. , Baumgartner M. , Goddeeris B. M. 
Published: June 2008

SummaryDietary addition of the leucine metabolite β‐hydroxy‐β‐methylbutyrate (HMB) promotes growth in various species. In addition, HMB is described to enhance immune responses which might be associated with metabolic costs. We elaborated further on the role of HMB in growth, metabolism and immunity of meat‐type chickens using the following parameters: zootechnical performance, blood chemistry and a specific immune responses after immunization with a human serum albumin (HSA)/Freund’s (in) complete adjuvant combination. The chickens received commercial feeds either unsupplemented or supplemented with 300 mg HMB/kg feed. β‐hydroxy‐β‐methylbutyrate‐supplemented chickens were significantly heavier at 2 weeks of age but this difference was attenuated at later ages. Compared with their unsupplemented controls, cumulative feed conversion was significantly lower in HMB‐supplemented chickens. There were no differences in blood chemistry between both dietary treatments. After immunization, HMB significantly attenuated the acute phase protein response at day 1 of post‐immunization compared with that of their unsupplemented counterparts. After day 7 post‐immunization, body weight gain of the immuno‐challenged HMB‐supplemented chickens was significantly depressed, but their specific anti‐HSA IgG response was significantly enhanced compared with that of their immuno‐challenged unsupplemented counterparts. The underlying mechanisms and signalling pathways for these phenomena need to be elucidated. Nevertheless, we are able to conclude that HMB is beneficial for performance under normal circumstances. On the other hand, HMB stimulates the immune response after an immunological challenge, though at the cost of reduced growth.
Population Structure and Genetic Diversity within Peach latent mosaic viroid Field Isolates from Peach Showing three Symptoms
Authors: Xu W. , Hong N. , Wang G. , Fan X. 
Published: June 2008

AbstractTo gain insight into the molecular basis of field isolates inducing the symptoms of leaf yellowing, discolouration along leaf sides and leaf mosaic, six isolates from peach showing the three different symptoms in the field were studied by single‐strand conformation polymorphism analysis and nucleotide sequence analysis. Results revealed that each Peach latent mosaic viroid (PLMVd) isolate is composed of a population of genetically related variants (haplotypes), one being predominant with frequencies from 32% to 57%, and most of others having a low frequency of 4–5%. Each predominant haplotype was sequenced, as well as some non‐predominant haplotypes selected randomly for comparative purposes. In each isolate, sequence alignment among the predominant and non‐predominant haplotypes demonstrated that the predominant haplotype had the least variation with others among them, and its sequence was identical to the consensus sequence, which inflected that the predominant haplotype displayed a wide representative of sequence for others in a PLMVd isolate. The similarities and genetic distance between the predominant sequences from peach showing the same symptoms were higher and smaller, respectively, than that with different symptoms; they were more than 98.8% and <1%, respectively, between the predominant sequences with same symptomatic source, and were <98.5% and more than 1%, respectively, between the predominant sequences with different symptomatic source. Some particular variations were indicated for these isolates, and it revealed that the isolates with the symptom of discolouration along leaf sides on their source peach trees had a G or U in position 169 nt, and the isolates with the symptom of leaf yellowing had U and C in 115 and 116 nt, respectively, and the isolates with the symptom of leaf mosaic showed diversity at (3 nt: delete C; 5 nt: A and 54 nt: U).
A Simple Method for the Assessment of Crown Rot Disease Severity in Wheat Seedlings Inoculated with Fusarium pseudograminearum
Authors: Li Xiangmin , Liu Chunji , Chakraborty Sukumar , Manners John M. , Kazan Kemal 
Published: June 2008

AbstractCrown rot caused by Fusarium pseudograminearum (teleomorph: Gibberella coronicola) is a serious disease of wheat. A simple and reliable method for assessing this disease would enhance our capacity in identifying resistance sources and developing resistant wheat cultivars. In searching for such a method, several inoculation techniques were tested. One technique, soaking 1‐ to 4‐day old seedlings in fungal spore suspension, produced consistent and severe crown rot symptoms. Glasshouse testing of several wheat genotypes using this method produced results that agreed well with previously established field ratings for crown rot disease, suggesting that this assay can be conveniently employed for screening of wheat genotypes for crown rot resistance.
Sun and landscape orientation in adult and juvenile sandhoppers Orchestoidea tuberculata (Amphipoda, Talitridae) from two beaches in south central Chile
Authors: Scapini Felicita , Dugan Jenifer 
Published: June 2008

AbstractThe behaviour of a talitrid amphipod, Orchestoidea tuberculata Nicolet 1849, was investigated for populations inhabiting two exposed sandy beaches in south central Chile to evaluate orientation capabilities with respect to sun azimuthal changes and landscape. The study beaches (Calfuco and La Misión) were backed by high cliffs but differed in shoreline orientation. Under test conditions of dry substrate, both populations oriented seawards using celestial cues when landscape vision was screened off and showed a higher concentration seawards when they could see the landscape suggesting additive effects of these cues. The absence of a phototactic response to the sun implies the involvement of an inner circadian clock, as the experiments were conducted at different times of the day. The distribution of juveniles was more concentrated than adults in the trials, a result in accordance with their tendency to occupy a zone located closer to the water than adults. Our results suggest that the Calfuco population was oriented to its shoreline, while animals at La Misión tended to deviate from the expected direction and their distribution was more scattered. This observed difference between the populations may be related to the higher human impact on the latter beach, which was more intensively used for recreation and periodically cleaned, removing the wrack. The comparison of results on orientation of O. tuberculata with those of different sandhopper species contributes new phylogenetic insight concerning this important adaptation. This study not only represents an extension of contemporary knowledge of behavioural adaptations of beach amphipods to coasts differing geographically and ecologically, but also analyses orientation in a southern Pacific species of talitrid amphipod for the first time.
Sandy beach ecosystems: key features, sampling issues, management challenges and climate change impacts
Authors: Schlacher Thomas A. , Schoeman Dave S. , Dugan Jenifer , Lastra Mariano , Jones Alan , Scapini Felicita , McLachlan Anton 
Published: June 2008

AbstractEscalating pressures caused by the combined effects of population growth, demographic shifts, economic development and global climate change pose unprecedented threats to sandy beach ecosystems worldwide. Conservation of beaches as functional ecosystems and protection of their unique biodiversity requires management interventions that not only mitigate threats to physical properties of sandy shores, but also include ecological dimensions. Yet, beach management remains overwhelmingly focused on engineering interventions. Here we summarise the key outcomes of several workshops, held during the 2006 Sandy Beach Ecology Symposium in Vigo, Spain, that addressed issues of climate change, beach management and sampling methodology. Because efficient communication between managers and ecologists is critical, we summarise the salient features of sandy beaches as functional ecosystems in 50 ‘key statements’; these provide a succinct synopsis of the main structural and functional characteristics of these highly dynamic systems. Key outcomes of the workshops include a set of recommendations on designs and methods for sampling the benthic infaunal communities of beaches, the identification of the main ecological effects caused by direct and indirect human interventions, the predicted consequence of climate change for beach ecosystems, and priority areas for future research.
Measuring species richness on sandy beach transects: extrapolative estimators and their implications for sampling effort
Authors: Schoeman David S , Nel Ronel , Goulart Soares Alexandre 
Published: June 2008

AbstractSpecies richness is a measure that is fundamental to many studies in ecology, and it is particularly important on sandy beaches, where it underlies patterns described by the broadly accepted swash exclusion hypothesis. However, its estimation in practice is problematic. This has led ecologists in other fields to adopt extrapolative estimators of species richness, which project the total number of species present in a habitat by adjusting upward the number of species observed by an amount related to the number of rare species encountered in the samples. In so doing, the species richness can be estimated, with confidence intervals, at any level of sampling effort. Despite the availability and advantages of these methods, beach ecologists have continued to use the observed species richness as a point estimate of biodiversity for beaches. Here, we employ a Monte Carlo resampling approach over a range of routine transect designs used to sample sandy beaches, and evaluate the performance of seven non‐parametric extrapolative estimators for species richness relative to that of the more conventionally used observed species richness. We find that the first‐order Jackknife estimator (Jack 1) is the least biased, most accurate and most consistent across sites. Employing this estimator would allow accurate estimation of species richness on short (tens of metres) stretches of beach without exceeding the acceptable levels of sampling effort (4–5 m2). Spreading this effort evenly over three across‐shore transects, each with a minimum of 13 equally spaced levels seems appropriately efficient. Although a greater number of research studies is required to ascertain the generality of these results beyond the beaches we sampled, we tentatively recommend the application of our results in biodiversity surveys on sandy beaches.