bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA taxonomy, phylogeny and Pleistocene diversification of the Cicindela hybrida species group (Coleoptera: Cicindelidae)
Authors: CARDOSO A. , VOGLER A. P. 
Published: September 2005

AbstractSpecies delimitation is complicated where morphological variation is continuous or poorly subdivided, but for taxonomic convenience it is common practice to separate and name geographical groups to capture this variation. DNA‐based approaches may be used to test if these groups in fact represent historically divided, discrete species entities. The Cicindela hybrida complex (Coleoptera: Cicindelidae) is an assemblage of up to seven morphologically recognized species and 15 subspecies with wide distribution in the Palaearctic region. We sequenced a discontinuous segment of 1899 bp of mtDNA including three regions (coxI, rrnL+trnL2+nad1, cob) for a total of 99 specimens from 36 sampling localities across Europe, revealing 48 haplotypes. Four major clades could be identified corresponding to geographical groups from central Iberia, Ukraine, central Europe, and a band from the Atlantic Iberian coast to northern Europe. Taking into account further subdivisions within these clades, four of the six named species included in the analysis were recognizable by applying various procedures for species delimitation. Age estimates from calibrated molecular clocks date the diversification of the hybrida group within the past 2 million years (Myr), and the separation of the northern clade within 0.4 Myr. Nested clade analysis revealed the rapid range expansion of the northern group consistent with postglacial dispersal, but we did not find support for specific source population(s) in the postulated southern refugia. The evolutionary framework based on mtDNA sequences is shown to identify species entities as discrete clusters of closely related sequences and provides an objective system for delineating and recognizing hierarchically structured groups. In the case of the C. hybrida complex, these groups largely coincided with those established from morphology. The study adds further support to the utility of mtDNA‐based sequence profiles (the ‘DNA taxonomy’) as a rapid and objective synthesis of evolutionary diversity and as reference system for communication.
Heterozygosity, inbreeding and neonatal traits in Soay sheep on St Kilda
Authors: OVERALL A. D. J. , BYRNE K. A. , PILKINGTON J. G. , PEMBERTON J. M. 
Published: September 2005

AbstractWe investigated whether birth weight and neonatal survival, a period within which 24% of all mortalities occur, were correlated with levels of inbreeding in St Kilda Soay sheep, using pedigree inbreeding coefficients and four marker‐based estimators of inbreeding. None of the inbreeding estimators, either of the offspring, or of their mothers, explained significant variation in a lamb's birth weight or probability of surviving the neonatal period, suggesting low inbreeding depression for these traits. We evaluated the correlation between the marker‐based measures of inbreeding and inbreeding coefficients obtained from the Soay pedigree, where paternal links were inferred using the same panel of microsatellite markers. Even when using a relatively complete portion of the pedigree, in which all individuals had known maternal and paternal grandparents, the correlation was found to be weak (r = −0.207, where meanf = 0.0168). These results add support to the recent prediction that when the mean and variance in inbreeding are low in a population, heterozygosity–fitness correlations can be very weak or even undetectable. The pursuit of more detailed pedigrees offers the best prospect for identifying inbreeding depression within this study population.
Molecular evidence for glacial refugia of mountain plants in the European Alps
Authors: SCHÖNSWETTER P. , STEHLIK I. , HOLDEREGGER R. , TRIBSCH A. 
Published: September 2005

AbstractMany mountain ranges have been strongly glaciated during the Quaternary ice ages, and the locations of glacial refugia of mountain plants have been debated for a long time. A series of detailed molecular studies, investigating intraspecific genetic variation of mountain plants in the European Alps, now allows for a first synopsis. A comparison of the phylogeographic patterns with geological and palaeoenvironmental data demonstrates that glacial refugia were located along the southwestern, southern, eastern and northern border of the Alps. Additional glacial refugia were present in central Alpine areas, where high‐elevation plants survived the last glaciation on ice‐free mountain tops. The observed intraspecific phylogeographies suggest general patterns of glacial survival, which conform to well‐known centres of Alpine species diversity and endemism. This implies that evolutionary or biogeographic processes induced by climatic fluctuations act on gene and species diversity in a similar way.
Mitochondrial DNA analysis of the bark beetle predator Thanasimus dubius F. (Coleoptera: Cleridae) reveals regional genetic differentiation
Authors: SCHREY NATALIE M. , REEVE JOHN D. , ANDERSON FRANK E. 
Published: September 2005

AbstractThe checkered beetle, Thanasimus dubius F., is an important predator of scolytid bark beetles that attack conifers. Relatively few studies exist that have addressed the population genetics of predatory beetles, especially those with potential as biological control agents. This study was conducted to investigate the population genetics of T. dubius across a large part of its range in the eastern United States. A 464‐base pair portion of the mitochondrial cytochrome c oxidase subunit I was sequenced for 85 individuals resulting in 60 haplotypes. Analysis of molecular variance was conducted on the resulting haplotypes for all populations and as a hierarchical analysis between populations defined as broad‐scale northern and southern groups. Results indicate a significant overall ΦST = 0.220 (P < 0.001) for all populations with the hierarchical analysis revealing that this significant ΦST is due to structuring of the populations between northern and southern regions (ΦCT = 0.388, P < 0.009). The observed genetic structure is possibly due to the discontinuous distribution of pine trees, which act as hosts for the prey of T. dubius, which has occurred historically in the central region of the United States that has been covered by prairie.
Deciphering host migrations and origins by means of their microbes
Authors: WIRTH THIERRY , MEYER AXEL , ACHTMAN MARK 
Published: September 2005

AbstractMitochondrial DNA and microsatellite sequences are powerful genetic markers for inferring the genealogy and the population genetic structure of animals but they have only limited resolution for organisms that display low genetic variability due to recent strong bottlenecks. An alternative source of data for deciphering migrations and origins in genetically uniform hosts can be provided by some of their microbes, if their evolutionary history correlates closely with that of the host. In this review, we first discuss how a variety of viruses, and the bacterium Helicobacter pylori, can be used as genetic tracers for one of the most intensively studied species, Homo sapiens. Then, we review statistical problems and limitations that affect the calculation of particular population genetic parameters for these microbes, such as mutation rates, with particular emphasis on the effects of recombination, selection and mode of transmission. Finally, we extend the discussion to other host–parasite systems and advocate the adoption of an integrative approach to both sampling and analysis.
Co‐infected C57BL/6 mice mount appropriately polarized and compartmentalized cytokine responses to Litomosoides sigmodontis and Leishmania major but disease progression is altered
Authors: LAMB T. J. , GRAHAM A. L. , LE GOFF L. , ALLEN J. E. 
Published: September 2005

SUMMARY This study examines the capacity of the mammalian host to fully compartmentalize the response to infection with type 1 vs. type 2 inducing organisms that infect different sites in the body. For this purpose, C57BL/6 mice were infected with the rodent filarial nematode Litomosoides sigmodontis followed by footpad infection with the protozoan parasite Leishmania major. In this host, nematode infection is established in the thoracic cavity but no microfilariae circulate in the bloodstream. We utilized quantitative ELISPOT analysis of IL‐4 and IFN‐γ producing cells to assess cytokine bias and response magnitude in the lymph nodes draining the sites of infection as well as more systemic responses in the spleen and serum. Contrary to other systems where co‐infection has a major impact on bias, cytokine ratios were unaltered in either local lymph node. The most notable effect of co‐infection was an unexpected increase in the magnitude of the IFN‐γ response to L. major in mice previously infected with L. sigmodontis. Further, lesion development was significantly delayed in these mice. Thus, despite the ability of the immune system to appropriately compartmentalize the immune response, interactions between responses at distinct infection sites can alter disease progression.
Comparison of Schistosoma mansoni irradiated cercariae and Sm23 DNA vaccines
Authors: GANLEY‐LEAL L. M. , GUARNER J. , TODD C. W. , DA'DARA A. A. , FREEMAN G. L. , BOYER A. E. , HARN D. A. , SECOR W. E. 
Published: September 2005

SUMMARY Immunization with defined antigens is generally less effective at inducing host protection against experimental infection with Schistosoma mansoni than vaccination with attenuated infective cercariae. We predicted that quantitative and/or qualitative differences existed between the immune responses generated to attenuated cercariae and those induced by defined antigens. Thus, we compared immune responses typically associated with protection in the murine model between animals vaccinated with attenuated cercariae and mice immunized with DNA encoding Sm23, a schistosome integral membrane protein that has previously been shown to confer protection. Mice vaccinated three times with attenuated cercariae demonstrated higher levels of protection than Sm23‐vaccinated animals but spleen cells from Sm23 DNA vaccinated mice produced significantly higher levels of schistosome antigen‐specific IFN‐γ. Both vaccines induced similar levels of Sm23‐specific antibody and post‐challenge dermal inflammation. However, the pulmonary inflammatory responses following challenge were much less pronounced in DNA immunized animals compared to those receiving irradiated cercariae. Thus, although Sm23 DNA vaccination effectively induced parasite‐specific IFN‐γ and antibody responses, it failed to evoke other critical responses needed for optimal vaccine efficacy.
Nitrogen delivery to maize via mycorrhizal hyphae depends on the form of N supplied
Authors: TANAKA YOKO , YANO KATSUYA 
Published: September 2005

ABSTRACTArbuscular mycorrhizal fungi can enhance nutrient acquisition by a plant via their extraradical hyphae. This is particularly true for phosphorus, but the case for nitrogen (N) has been less clear. In our growth systems there was a small air‐gap between root and hyphal compartments, which eliminated diffusion of nutrients between compartments. Moreover, our methods allowed us to distinguish between nitrate and ammonium. We found that N transfer to Zea maize L. depends on the sources fed to the hyphae of Glomus aggregatum Schenck & Smith. In experiment 1, despite the fact that plant demand for N was already met, plants received 10 times as much 15N from ammonium than from nitrate. In experiment 2, 74% of shoot‐N was derived from the slow‐release urea added to the hyphal compartment while only 2.9% was derived from the nitrate‐N. Intraradical hyphae isolated from roots contained a considerable amount of 15N in the cell wall even when 15N‐nitrate was the source. We conclude that the mycorrhizal fungus can rapidly deliver ammonium‐N to the plants, and that while the fungus can absorb nitrate, it apparently lacks the capacity to transfer it to the plant.
Screening plants for salt tolerance by measuring K+ flux: a case study for barley
Authors: CHEN Z. , NEWMAN I. , ZHOU M. , MENDHAM N. , ZHANG G. , SHABALA S. 
Published: September 2005

ABSTRACTDevelopment of salt‐tolerant genotypes is central both to remediation of salinity‐affected land and to meet increasing global food demand, which has been driving expansion of cropping into marginal areas. The bottleneck of any breeding programme is the lack of a reliable screening technique. This study tested the hypothesis that the ability of plants to retain K+ under saline conditions is central to their salt tolerance. Using seven barley cultivars contrasting in salt tolerance (CM72, Numar, ZUG293, ZUG95, Franklin, Gairdner, ZUG403), a comprehensive study was undertaken of whole‐plant (growth rate, biomass, net CO2 assimilation, chlorophyll fluorescence, root and leaf elemental and water content) and cellular (net fluxes of H+, K+, Na+ and Ca2+) responses to various concentrations of NaCl (20–320 m m). Na+ selective microelectrodes were found to be unsuitable for screening purposes because of non‐ideal selectivity of the commercially available Na+ LIX. At the same time, our results show very strong negative correlation between the magnitude of K+ efflux from the root and salt tolerance of a particular cultivar. K+ efflux from the mature root zone of intact 3‐day‐old seedlings following 40 min pretreatment with 80 m m NaCl was found to be a reliable screening indicator for salinity tolerance in barley. As a faster and more cost‐effective alternative to microelectrode measurements, a procedure was developed enabling rapid screening of large numbers of seedlings, based on amount of K+ leaked from plant roots after exposure to NaCl.
Sap salinity effects on xylem conductivity in two mangrove species
Authors: LÓPEZ‐PORTILLO JORGE , EWERS FRANK W. , ANGELES GUILLERMO 
Published: September 2005

ABSTRACTXylem sap salinity and conductivity were examined in two mangrove ecosystem tree species. For Avicennia germinans, extracted xylem sap osmotic potentials ranged from −0.24 to −1.36 MPa versus −0.14 to −0.56 MPa for Conocarpus erectus. Xylem sap of Conocarpus did not vary in osmotic potential between sites nor between predawn and midday. In Avicennia, values were more negative at midday than predawn, and also more negative at hypersaline than hyposaline sites. After removing embolisms, specific conductivity (Ks) was measured as a function of salinity of the artificial xylem sap perfusion. For both species the lowest Ks values, about 70% of the maximum Ks, were obtained when stems were perfused with deionized water (0 mm; 0.0 MPa) or with a 557‐mm saline solution (−2.4 MPa). Higher Ks values were obtained in the range from −0.3 to −1.2 MPa, with a peak at −0.82 ± 0.08 MPa for Avicennia and −0.75 ± 0.08 MPa for Conocarpus. The variations in Ks values with minima both at very low and very high salt concentrations were consistent with published results for swelling and shrinking of synthetic hydrogels, suggesting native hydrogels in pit membranes of vessels could help regulate conductivity.
Are the carbon costs of seed production related to the quantitative and qualitative performance? An appraisal for legumes and other crops
Authors: MUNIER‐JOLAIN NATHALIE G. , SALON CHRISTOPHE 
Published: September 2005

ABSTRACTIn the past great efforts have been made to gain a thorough understanding of the processes involved in carbon fixation but the fate of the acquired carbon has been somewhat neglected, although this aspect is crucial for improving yield performance without diminishing the quality of the harvested organs. To contribute to the crucial debate on that topic the aim of the present study was to propose some unbiased components concerning in particular grain legumes: ‘Is there any antagonism between high yield and increased nutritional quality, with a focus on protein content?’ An original approach has been used to study the impact of the modification of seed composition on the crop production, which combines theoretical calculations of energetic cost and field yield data. When applied to a wide range of species with varying seed composition, a plurispecific negative relationship between the theoretical carbon costs of seed production and the observed yields was demonstrated. The high‐throughput of genetic markers could result in large‐scale screening of seed quality parameters and such studies, while evaluating the impact of seed composition on crop yield, could also be used to provide data to forecast the economic impact of a new line with an original composition compared with its economically enhanced value.
Photosynthesis and carbohydrate metabolism in tobacco leaves during an incompatible interaction with Phytophthora nicotianae
Authors: SCHARTE JUDITH , SCHÖN HARDY , WEIS ENGELBERT 
Published: September 2005

ABSTRACTThe metabolic and cellular changes in source leaves of Nicotiana tabacum L. cv SNN during an incompatible interaction with Phytophthora nicotianae van Breda de Haan were investigated and compared with defence reactions. Hypersensitive cell death was preceded by a rapid and highly localized shift to non‐assimilatoric metabolism. During the first 6 h post infection (hpi), reactive oxygen species (ROS) accumulated. Callose was deposited at the interface of adjacent mesophyll cells (≥1 hpi), the export of sucrose collapsed and its content in the apoplast increased. Stomata closed and photosynthetic flux was reallocated from CO2 assimilation in favour of photorespiration. This was accompanied by an increase in respiration, glucose‐6‐phosphate dehydrogenase (G6PDH) activity, apoplastic invertase and hexose content. Later (>6 hpi) the photosynthetic electron transport chain was interrupted and photosynthesis completely collapsed. This was accompanied by a further increase in apoplastic invertase and carbohydrates, respiration and oxidative pentose phosphate pathway (OPPP) and followed by further burst in ROS release. Hypersensitive cell death did not appear until photosynthesis completely declined. Photosynthesis was visualized by chlorophyll‐a fluorescence imaging on a macro‐ and microscopic scale. Decline in photosynthesis and defence reactions were highly localized processes, which occur in single mesophyll cells. We propose that in photoautotrophic leaves, photosynthesis and assimilatory metabolism must be switched off to initiate respiration and other processes required for defence. An early blockage of intercellular sugar transportation, due to callose deposition, in conjunction with enhanced apoplastic invertase activity could facilitate this metabolic shift.
Ascorbate promotes emission of mercury vapour from plants
Authors: BATTKE FLORIAN , ERNST DIETER , HALBACH STEFAN 
Published: September 2005

ABSTRACTMercury vapour (Hg°) emission from plants contributes to the atmospheric mercury cycle. Although a part of this Hg° emission originates from Hg(II) uptake by the roots, the question how terrestrial plants reduce Hg(II) has not been addressed so far. Young barley plants grown on a hydroponic cultivation containing Hg(II) increased the Hg° emission significantly. Homogenates of barley leaves added to dissolved Hg(II) induced a powerful volatilization at alkaline but not at acidic pH. The same pH dependence and emission kinetic together with the highest reduction capacity was observed for ascorbic acid as compared to other phytoreductants. The electrochemical potentials of the reactions involved suggest an electron transfer from NADPH via GSH and ascorbate to Hg(II). The results support the assumption of a novel mechanism how plants transfer reduction equivalents from the antioxidative defense system via ascorbate to reduce Hg(II) ions, thus counteracting mercury toxicity by volatilizing the metal. This effect appears to be assisted by other light‐dependent processes such as transpiration and ascorbate synthesis.
Leaf growth dynamics of two congener gymnosperm tree species reflect the heterogeneity of light intensities given in their natural ecological niche
Authors: LAI I‐LING , SCHARR HANNO , CHAVARRIA‐KRAUSER ANDRES , KÜSTERS RALF , WU JIUNN‐TZONG , CHOU CHANG‐HUNG , SCHURR ULRICH , WALTER ACHIM 
Published: September 2005

ABSTRACT Chamaecyparis obtusa var. formosana and Chamaecyparis formosensis are congener gymnosperm tree species native to Taiwan cloud forests; occupying different niches there. While the seedlings of C. formosensis occur predominantly under bright conditions in large forest gaps, seedlings of C. obtusa var. formosana are mainly found below the canopy of mature forests or in small gaps. It is well known that congener species occupying different niches typically differ in several ecophysiological and morphological traits, but the differences in growth dynamics of such species are still totally unclear, as the diurnal growth dynamics of gymnosperm leaves have not been investigated before. Modern methods of digital image sequence processing were used in this study to analyse the leaf growth dynamics of the two species. We found that both species show similar base–tip gradients and pronounced diurnal growth rhythms with maxima in the evening. Differences between the two species concerning their growth dynamics correlated closely with their ecological amplitudes and abundances. Chamaecyparis obtusa var. formosana grew faster than C. formosensis in low light intensity, typical for closed‐canopy situations, and reacted quickly by increasing or decreasing growth rate when light intensity changed within a range typically found below small canopy gaps. In contrast to this, C. formosensis grew better in light intensities typical for open vegetation situations, but reacted slower towards changes of light intensity. Based on those results, the hypothesis can be developed that fluctuations of leaf growth dynamics reflect heterogeneities of the light environment within the niche occupied by a given species.
Cold‐induced repression of the rice anther‐specific cell wall invertase gene OSINV4 is correlated with sucrose accumulation and pollen sterility
Authors: OLIVER SANDRA N. , VAN DONGEN JOOST T. , ALFRED SANJEEV C. , MAMUN EZAZ A. , ZHAO XIAOCHUN , SAINI HARGURDEEP S. , FERNANDES SUSSAN F. , BLANCHARD CHRISTOPHER L. , SUTTON BRUCE G. , GEIGENBERGER PETER , DENNIS ELIZABETH S. , DOLFERUS RUDY 
Published: September 2005

ABSTRACTLow temperatures during rice (Oryza sativa L.) pollen development cause pollen sterility and decreased grain yield. We show that the time of highest sensitivity to cold coincides with the time of peak tapetal activity: the transition of the tetrad to early uni‐nucleate stage (young microspore, YM stage). Low temperatures at this stage of pollen development result in an accumulation of sucrose in the anthers, accompanied by decreased activity of cell wall bound acid invertase and depletion of starch in mature pollen grains. Expression analysis of two cell wall (OSINV1, 4) and one vacuolar (OSINV2) acid invertase genes showed that OSINV4 is anther‐specific and down‐regulated by cold treatment. OSINV4 is transiently expressed in the tapetum cell layer at the YM stage, and later from the early binucleate stage in the maturing microspores. The down‐regulation of OSINV4 expression in the tapetum at YM may cause a disruption in hexose production and starch formation in the pollen grains. In a cold‐tolerant cultivar, OSINV4 expression was not reduced by cold; sucrose did not accumulate in the anthers and starch formation in the pollen grains was not affected.