bluuebunny/crossref_metadata_2025_split huggingface dataset:
Female house wrens (Troglodytes aedon) increase the size, but not immunocompetence, of their offspring through extra‐pair mating
Authors: FORSMAN ANNA M.  , VOGEL LAURA A.  , SAKALUK SCOTT K.  , JOHNSON BONNIE G.  , MASTERS BRIAN S.  , JOHNSON L. SCOTT , THOMPSON CHARLES F.  
Published: July 2008

AbstractHouse wrens are typically socially monogamous, but frequently engage in extra‐pair matings leading to multisired broods. Because females do not appear to acquire direct material benefits from their extra‐pair mates, we tested the hypothesis that female house wrens derive indirect genetic benefits, such as enhanced immunocompetence (cutaneous immune activity, humoral immunity, and plasma bactericidal activity) and condition (size and haematoserological traits) for their offspring, by mating polyandrously. We predicted that extra‐pair young (EPY) should show greater immune responsiveness and better body condition than their within‐pair maternal half‐siblings (WPY). Contrary to our prediction, WPY had higher cutaneous immune activity than their EPY brood‐mates in two of three years, and EPY and WPY did not differ in measures of innate and humoral immunity. WPY also had higher albumin to γ‐globulin ratios than EPY; however, they were not in better condition based on other measures. EPY had consistently longer tarsi (a measure of long‐bone size) than their WPY half‐siblings, suggesting that females engage in extra‐pair copulations with larger males. The benefits of large structural size in the study population is unknown, but based on evidence from other passerines, we suggest that structural size may be an important fitness‐related trait in house wrens. We conclude that our results are not consistent with the hypothesis that females gain immune‐related benefits for their offspring by engaging in extra‐pair matings. Further study of the fitness consequences of differences in tarsus length is needed to determine whether females acquire size‐related benefits for their offspring from extra‐pair mates.
A SINE of restricted gene flow across the Alpine Fault: phylogeography of the New Zealand common skink (Oligosoma nigriplantare polychroma)
Authors: LIGGINS LIBBY , CHAPPLE DAVID G. , DAUGHERTY CHARLES H. , RITCHIE PETER A. 
Published: July 2008

AbstractNew Zealand has experienced a complex climatic and geological history since the Pliocene. Thus, identifying the processes most important in having driven the evolution of New Zealand's biota has proven difficult. Here we examine the phylogeography of the New Zealand common skink (Oligosoma nigriplantare polychroma) which is distributed throughout much of New Zealand and crosses many putative biogeographical boundaries. Using mitochondrial DNA sequence data, we revealed five geographically distinct lineages that are highly differentiated (pairwise ΦST 0.54–0.80). The phylogeographical pattern and inferred age of the lineages suggests Pliocene mountain building along active fault lines promoted their divergence 3.98–5.45 million years ago. A short interspersed nuclear element (SINE) polymorphism in the myosin gene intron (MYH‐2) confirmed a pattern of restricted gene flow between lineages on either side of the mountain ranges associated with the Alpine Fault that runs southwest to northeast across the South Island of New Zealand. An analysis of molecular variance confirmed that ~40% of the genetic differentiation in O. n. polychroma is distributed across this major fault line. The straits between the main islands of New Zealand accounted for much less of the variation found within O. n. polychroma, most likely due to the repeated existence of landbridges between islands during periods of the Pleistocene that allowed migration. Overall, our findings reveal the relative roles of different climatic and geological processes, and in particular, demonstrate the importance of the Alpine Fault in the evolution of New Zealand's biota.
Invasion of Europe by the western corn rootworm, Diabrotica virgifera virgifera: multiple transatlantic introductions with various reductions of genetic diversity
Authors: CIOSI M. , MILLER N. J. , KIM K. S. , GIORDANO R. , ESTOUP A. , GUILLEMAUD T. 
Published: July 2008

AbstractThe early stages of invasion involve demographic bottlenecks that may result in lower genetic variation in introduced populations as compared to source population/s. Low genetic variability may decrease the adaptive potential of such populations in their new environments. Previous population genetic studies of invasive species have reported varying levels of losses of genetic variability in comparisons of source and invasive populations. However, intraspecific comparisons are required to assess more thoroughly the repeatability of genetic consequences of colonization events. Descriptions of invasive species for which multiple introductions from a single source population have been demonstrated may be particularly informative. The western corn rootworm (WCR), Diabrotica virgifera virgifera, native to North America and invasive in Europe, offers us an opportunity to analyse multiple introduction events within a single species. We investigated within‐ and between‐population variation at eight microsatellite markers in WCR in North America and Europe to investigate the routes by which WCR was introduced into Europe, and to assess the effect of introduction events on genetic variation. We detected five independent introduction events from the northern USA into Europe. The diversity loss following these introductions differed considerably between events, suggesting substantial variation in introduction, foundation and/or establishment conditions. Genetic variability at evolutionarily neutral loci does not seem to underlie the invasive success of WCR in Europe. We also showed that the introduction of WCR into Europe resulted in the redistribution of genetic variance from the intra‐ to the interpopulational level contrary to most examples of multiple introductions.
Phylogeographical structure and temporal complexity in American sweetgum (Liquidambar styraciflua; Altingiaceae)
Authors: MORRIS ASHLEY B. , ICKERT‐BOND STEFANIE M. , BRUNSON D. BURKE , SOLTIS DOUGLAS E. , SOLTIS PAMELA S. 
Published: July 2008

AbstractEastern North American plant biogeography has traditionally focused on two primary issues: (i) the location of temperate Pleistocene refugia and their proximity to the southern margin of the ice sheet during the last glacial maximum, and (ii) the origin of the temperate element of northern Latin America. While numerous population genetic and phylogeographical studies have focused on the first issue, few (if any) have considered the second. We addressed these issues by surveying 117 individuals from 24 populations of Liquidambar styraciflua (American sweetgum; Altingiaceae) across the southeastern USA, eastern Mexico, and Guatemala, using more than 2200 bp of chloroplast DNA sequence data. To specifically address the issue of timing, we estimated intraspecific divergence times on the basis of multiple fossil‐based calibration points, using taxa from Altingiaceae (Liquidambar and Altingia) and Hammamelidaceae (Hamamelis) as outgroups. More than half of the sampled localities exhibited multiple haplotypes. Remarkably, the greatest variation was observed within the USA, with Mexico and Guatemala sharing widespread haplotypes with Texas, Mississippi, Kentucky, Ohio, and northern Virginia. This lack of differentiation suggests shared ancestral polymorphisms, and that the genetic signal we observed is older than the disjunction itself. Our data provide support for previously proposed hypotheses of Pleistocene refugia in peninsular Florida and along the eastern Atlantic, but also for deeper divergences (~8 million years ago) within the USA. These patterns reflect a dynamic biogeographical history for eastern North American trees, and emphasize the importance of the inclusion of a temporal component in any phylogeographical study.
Transport and compartmentation of phosphite in higher plant cells – kinetic and 31P nuclear magnetic resonance studies
Authors: DANOVA‐ALT RALITZA , DIJKEMA COR , DE WAARD PIETER , KÖCK MARGRET 
Published: July 2008

ABSTRACTPhosphite (Phi, H2PO3‐), being the active part of several fungicides, has been shown to influence not only the fungal metabolism but also the development of phosphate‐deficient plants. However, the mechanism of phosphite effects on plants is still widely unknown. In this paper we analysed uptake, subcellular distribution and metabolic effects of Phi in tobacco BY‐2 cells using in vivo31P nuclear magnetic resonance (31P‐NMR) spectroscopy. Based on the kinetic properties of the phosphate transport system of tobacco BY‐2 cells, it was demonstrated that phosphite inhibited phosphate uptake in a competitive manner. To directly follow the fate of phosphate and phosphite in cytoplasmic and vacuolar pools of tobacco cells, we took advantage of the pH‐sensitive chemical shift of the Phi anion. The NMR studies showed a distinct cytoplasmic accumulation of Phi in Pi‐deprived cells, whereas Pi resupply resulted in a rapid efflux of Phi. Pi‐preloaded cells shifted Phi directly into vacuoles. These studies allowed for the first time to follow Phi flux processes in an in vivo setting in plants. On the other hand, the external Pi nutrition status and the metabolic state of the cells had a strong influence on the intracellular compartmentalization of xenobiotic Phi.
Molecular mechanisms underlying plant memory in JA‐mediated defence responses
Authors: GÁLIS IVAN , GAQUEREL EMMANUEL , PANDEY SHREE P. , BALDWIN IAN T. 
Published: July 2008

ABSTRACTPlants must respond to biotic and abiotic challenges to optimize their Darwinian fitness in nature. Many of these challenges occur repeatedly during a plant's lifetime, and their sequence and timing can profoundly influence the fitness outcome of a plant's response. The ability to perceive, store and recall previous stressful events is likely useful for efficient, rapid and cost‐effective responses, but we know very little about the mechanisms involved. Using jasmonate‐elicited anti‐herbivore defence responses as an example, we consider how ‘memories’ of previous attacks could be created in (1) the biosynthetic processes involved in the generation of the oxylipin bursts elicited by herbivore attacks; (2) the perception of oxylipins and their transduction into cellular events by transcription factors and transcriptional activators; and (3) the role of small RNAs in the formation of long‐term stress imprints in plants.
Depositional processes in a kimberlite crater: the Upper Cretaceous Orapa South Pipe (Botswana)
Authors: GERNON THOMAS M. , FIELD MATTHEW , SPARKS R. STEPHEN J. 
Published: July 2008

AbstractThe Orapa A/K1 Diamond Mine, Botswana, exposes the crater facies of a bilobate kimberlite pipe of Upper Cretaceous age. The South Crater consists of layered volcaniclastic deposits which unconformably cross‐cut massive volcaniclastic kimberlite of diatreme facies in the North Pipe. Based on the depositional structure, grain‐size, sorting and composition of kimberlite in the South Crater, six units are distinguished in the ∼70 m thick stratiform crater‐fill sequence and talus slope deposits close to the crater wall, which represents a multistage infill of the volcanic crater. Monolithic basalt breccias (Unit 1) near the base of the crater‐fill are interpreted as rock‐fall avalanche deposits, generated by the sector collapse of the crater walls. These deposits are overlain by a basal imbricated lithic breccia and upper massive sub‐unit (Unit 2), interpreted as the deposits of a pyroclastic flow that entered the South Crater from another source. Vertical degassing structures within the massive sub‐unit show evidence for elutriation of fines and probably were formed after emplacement by fluidization due to air entrainment. Units 3 and 5 are thinly stratified deposits, characterized by diffuse bedding, reverse and normal grading, coarse lenticular beds, mudstone beds, small‐scale scour channels and load casts. These units are attributed to rapidly emplaced sheet floods on the crater floor. Units 3 and 5 are directly overlain by poorly sorted volcaniclastic kimberlite (Units 4 and 6) rich in basalt boulders, attributed to debris flows formed by the collapse of crater walls. Unit 7 comprises medium sandstones to cobble conglomerates representing talus fans, which were active throughout the deposition of Units 1 to 6. The study demonstrates that much of the material infilling the South Crater is derived externally after eruption, including primary pyroclastic flow deposits probably from another kimberlite pipe. These findings have important implications for predicting diamond grade. Results may also aid the interpretation of crater sequences of ultra‐basic, basaltic and intermediate volcanoes, together with the deposits of topographic basins in sub‐aerial settings.
Characterization of Arabidopsis mur3 mutations that result in constitutive activation of defence in petioles, but not leaves
Authors: Tedman‐Jones Jennifer D. , Lei Rita , Jay Florence , Fabro Georgina , Li Xuemei , Reiter Wolf‐Dieter , Brearley Charles , Jones Jonathan D. G. 
Published: July 2008

SummaryA screen was established for mutants in which the plant defence response is de‐repressed. The pathogen‐inducible isochorismate synthase (ICS1) promoter was fused to firefly luciferase (luc) and a homozygous transgenic line generated in which the ICS1:luc fusion is co‐regulated with ICS1. This line was mutagenized and M2 seedlings screened for constitutive ICS1:luc expression (cie). The cie mutants fall into distinct phenotypic classes based on tissue‐specific localization of luciferase activity. One mutant, cie1, that shows constitutive luciferase activity specifically in petioles, was chosen for further analysis. In addition to ICS1, PR and other defence‐related genes are constitutively expressed in cie1 plants. The cie1 mutant is also characterized by an increased production of conjugated salicylic acid and reactive oxygen intermediates, as well as spontaneous lesion formation, all confined to petiole tissue. Significantly, defences activated in cie1 are sufficient to prevent infection by a virulent isolate of Hyaloperonospora parasitica, and this enhanced resistance response protects petiole tissue alone. Furthermore, cie1‐mediated resistance, along with PR gene expression, is abolished in a sid2‐1 mutant background, consistent with a requirement for salicylic acid. A positional cloning approach was used to identify cie1, which carries two point mutations in a gene required for cell wall biosynthesis and actin organization, MUR3. A mur3 knockout mutant also resists infection by H. parasitica in its petioles and this phenotype is complemented by transformation with wild‐type MUR3. We propose that perturbed cell wall biosynthesis may activate plant defence and provide a rationale for the cie1 and the mur3 knockout phenotypes.
A sequence‐anchored genetic linkage map for the moss, Physcomitrella patens
Authors: Kamisugi Yasuko , Von Stackelberg Mark , Lang Daniel , Care Matthew , Reski Ralf , Rensing Stefan A. , Cuming Andrew C. 
Published: July 2008

SummaryThe moss Physcomitrella patens is a model for the study of plant cell biology and, by virtue of its basal position in land plant phylogeny, for comparative analysis of the evolution of plant gene function and development. It is ideally suited for ‘reverse genetic’ analysis by virtue of its outstanding ability to undertake targeted transgene integration by homologous recombination. However, gene identification through mutagenesis and map‐based cloning has hitherto not been possible, due to the lack of a genetic linkage map. Using molecular markers [amplified fragment length polymorphisms (AFLP) and simple sequence repeats (SSR)] we have generated genetic linkage maps for Physcomitrella. One hundred and seventy‐nine gene‐specific SSR markers were mapped in 46 linkage groups, and 1574 polymorphic AFLP markers were identified. Integrating the SSR‐ and AFLP‐based maps generated 31 linkage groups comprising 1420 markers. Anchorage of the integrated linkage map with gene‐specific SSR markers coupled with computational prediction of AFLP loci has enabled its correspondence with the newly sequenced Physcomitrella genome. The generation of a linkage map densely populated with molecular markers and anchored to the genome sequence now provides a resource for forward genetic interrogation of the organism and for the development of a pipeline for the map‐based cloning of Physcomitrella genes. This will radically enhance the potential of Physcomitrella for determining how gene function has evolved for the acquisition of complex developmental strategies within the plant kingdom.
Tic40 is important for reinsertion of proteins from the chloroplast stroma into the inner membrane
Authors: Chiu Chi‐Chou , Min Li Hsou– 
Published: July 2008

SummaryChloroplast inner‐membrane proteins Tic40 and Tic110 are first imported from the cytosol into the chloroplast stroma, and subsequently reinserted from the stroma into the inner membrane. However, the mechanism of reinsertion remains unclear. Here we show that Tic40 itself is involved in this reinsertion process. When precursors of either Tic40 or a Tic110 C‐terminal truncate, tpTic110‐Tic110N, were imported into chloroplasts isolated from a tic40‐null mutant, soluble Tic40 and Tic110N intermediates accumulated in the stroma of tic40‐mutant chloroplasts, due to a slower rate of reinsertion. We further show that a larger quantity of soluble Tic21 intermediates also accumulated in the stroma of tic40‐mutant chloroplasts. In contrast, inner‐membrane insertion of the triose‐phosphate/phosphate translocator was not affected by the tic40 mutation. Our data suggest that multiple pathways exist for the insertion of chloroplast inner‐membrane proteins.
Measuring and comparing evolvability and constraint in multivariate characters
Authors: HANSEN T. F. , HOULE D. 
Published: July 2008

AbstractThe Lande equation forms the basis for our understanding of the short‐term evolution of quantitative traits in a multivariate context. It predicts the response to selection as the product of an additive genetic variance matrix and a selection gradient. The selection gradient approximates the force and direction of selection, and the genetic variance matrix quantifies the role of the genetic system in evolution. Attempts to understand the evolutionary significance of the genetic variance matrix are hampered by the fact that the majority of the methods used to characterize and compare variance matrices have not been derived in an explicit theoretical context. We use the Lande equation to derive new measures of the ability of a variance matrix to allow or constrain evolution in any direction in phenotype space. Evolvability captures the ability of a population to evolve in the direction of selection when stabilizing selection is absent. Conditional evolvability captures the ability of a population to respond to directional selection in the presence of stabilizing selection on other trait combinations. We then derive measures of character autonomy and integration from these evolvabilities. We study the properties of these measures and show how they can be used to interpret and compare variance matrices. As an illustration, we show that divergence of wing shape in the dipteran family Drosophilidae has proceeded in directions that have relatively high evolvabilities.
Cell death upon H2O2 induction in the unicellular green alga Micrasterias
Authors: Darehshouri A. , Affenzeller M. , Lütz‐Meindl U. 
Published: July 2008

AbstractIn the present study, we investigated whether the unicellular green alga Micrasterias denticulata is capable of executing programmed cell death (PCD) upon experimental induction, and which morphological, molecular and physiological hallmarks characterise this. This is particularly interesting as unicellular freshwater green algae growing in shallow bog ponds are exposed to extreme environmental conditions, and the capacity to perform PCD may be an important strategy to guarantee survival of the population. The theoretically ‘immortal’ alga Micrasterias is an ideal object for such investigations as it has served as a cell biological model system for many years and details on its growth properties, physiology and ultrastructure throughout the cell cycle are well known. Treatments with low concentrations of H2O2 are known to induce PCD in other organisms, resulting in severe ultrastructural changes to organelles, as observed in TEM. These include deformation and part disintegration of mitochondria, abnormal dilatation of cisternal rims of dictyosomes, occurrence of multivesicular bodies, an increase in the number of ER compartments, and slight condensation of chromatin. Additionally, a statistically significant increase in caspase‐3‐like activity was detected, which was abrogated by a caspase‐3 inhibitor. Photosynthetic activity measured by fast chlorophyll fluorescence decreased as a consequence of H2O2 exposure, whereas pigment composition, except for a reduction in carotenoids, was the same as in untreated controls. TUNEL positive staining and ladder‐like degradation of DNA, both frequently regarded as a hallmark of PCD in higher plants, could only be detected in dead Micrasterias cells.
Wheat (Triticum aestivum) seedlings secrete proteases from the roots and, after protein addition, grow well on medium without inorganic nitrogen
Authors: Adamczyk B. , Godlewski M. , Zimny J. , Zimny A. 
Published: July 2008

AbstractThis paper reports on the role of proteases secreted by roots in nitrogen capture by plants. The study was conducted on aseptically cultivated wheat seedlings (Triticum aestivum cv. Tacher) obtained from embryos isolated from grains. Seedlings were cultivated for 21 days on deionised water, Murashige Skoog medium (MS), MS without inorganic nitrogen (IN), and MS without IN, in which IN was replaced by casein (0.01%, 0.1% or 1%). Comparison of seedlings grown on these media showed that casein entirely compensated for the lack of inorganic nitrogen in the medium. Shoots and roots of seedlings cultivated on MS medium with this protein had higher fresh weight than those cultivated on MS medium without casein. The increase in fresh weight of seedlings was correlated with casein concentration and proteolytic activity in the medium. In conclusion, wheat that uses proteases secreted by the roots can directly utilise proteins in the medium as a source of nitrogen without prior digestion by microbial proteases and without protein mineralisation. These results suggest the important role of organic nitrogen fertilisers in increasing wheat yield.