bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection and analysis of genetic variation in Hordeum spontaneum populations from Israel using RAPD markers
Authors: DAWSON I. K. , CHALMERS K. J. , WAUGH R. , POWELL W. 
Published: April 2008

AbstractRandomly amplified polymorphic DNA (RAPD) markers were used to analyse genetic diversity within and between Hordeum spontaneum populations sampled from Israel. Nei's index of genetic differentiation was used to partition diversity into within and between population components. Fifty‐seven per cent of the variation detected was partitioned within 10 H. spontaneum populations. Using principal component and multiple regression analysis, part of the variation detected between populations was seen to be associated with certain ecogeographical factors. Fifty‐eight per cent of the distribution of the phenotypic frequencies of three RAPD phenotypes detected using a single primer in 20 H. spontaneum populations could be accounted for by four ecogeographical variables, suggesting adaptive variation at certain RAPD loci.
Phylogeny and historical aspects of the ecology of eastern Australian scrubwrens Sericornis spp. — evidence from mitochondrial DNA
Authors: JOSEPH L. , MORITZ C. 
Published: April 2008

AbstractA phylogeny of mainland eastern Australian scrubwrens (Sericornis citreogularis, S. frontalis, S. keri, S. tnagnirostris and S. beccarii) was constructed using presence or absence of phylogenetically informative restriction sites in 15 mitochondrial DNA (mtDNA) haplotypes. MtDNA sequence divergences between species were generally large (mostly between 10 and 18%) emphasizing the antiquity of this radiation. Phylogenetic analysis of the mtDNA resulted in a strongly supported phylogeny concordant with relationships suggested by a previous study of allozyme variation, but conflicting with concepts based on morphological similarity. The mtDNAs grouped the species into two lineages, one containing beccarii and tnagnirostris and the other comprising citreogularis, frontalis and keri. The mtDNAs of beccarii and tnagnirostris were paraphyletic with a northern variant of tnagnirostris being more similar to beccarii than other magnirostris. The mtDNA from keri was most closely related to that of frontalis and then citreogularis. The strongly corroborated molecular phylogeny confirms and extends the previous (Christidis et al. 1988; Auk 105 > 616) reinterpretation of morphological and ecological shifts in the group. This suggests considerable plasticity and parallelism in the plumage characters previously used to associate species. The low divergence and close relationship between the montane rain‐forest specialist keri and the widely distributed generalist frontalis demonstrate the capacity for evolutionarily rapid and dramatic shifts in habitat use. This contrasts with the assumption of fixed habitat preference that underlies refuge‐based models of diversification of rain‐forest fauna.
Plasmid DNA in a groundwater aquifer microcosm ‐adsorption, DNAase resistance and natural genetic transformation of Bacillus subtilis
Authors: ROMANOWSKI G. , LORENZ M. G. , WACKERNAGEL W. 
Published: April 2008

AbstractProkaryotes can exchange chromosomal and plasmid genes via extracellular DNA in a process termed genetic transformation. This process has been observed in the test tube for several bacterial species living in the environment but it is not clear whether transformation occurs in natural bacterial habitats. A major constituent of terrestrial environments are solid particles such as quartz, silt and clay, which have considerable surface areas and which make up the solid‐liquid interfaces of the habitat. In previous experiments the adsorption of DNA to chemically purified quartz and clay minerals was shown and the partial protection of adsorbed DNA against DNAase I. In a microcosm consisting of natural groundwater aquifer material (GWA) sampled directly from the environment and groundwater (GW) both linear duplex and supercoiled plasmid DNA molecules bound rapidly and quantitatively to the minerals. The divalent cations required to form the association were those present in the GWA/GW microcosm. The association was stable to extended elution over one week at 23°C. Upon adsorption, the DNA became highly resistant against enzymatic degradation. About 1000 times higher DNAase I concentrations were needed to degrade bound DNA to the same extent as DNA dissolved in GW. Furthermore, chromosomal and plasmid DNA bound on GWA transformed competent cells of Bacillus subtilis. However, in contrast to DNA in solution, on GWA the chromosomal DNA was more active in transformation than the plasmid DNA. The studies also revealed that in the transformation of B. subtilis Mg2+ can be replaced by Na+, K+ or NH4 The observations suggest that in soil and sediment environments, mineral material with inorganic precipitates and organic matter can harbour extracellular DNA leaving it available for genetic transformation.
Assessing the risks of transgene escape through time and crop‐wild hybrid persistence
Authors: LINDER C. R. , SCHMITT J. 
Published: April 2008

AbstractTransgenes introduced into crops can escape in time, as well as space, via the seed bank. For annual plants, especially ruderals, seed bank behaviour may be the most important factor determining population persistence. Crop seeds may exhibit some dormancy and germination cueing in the soil but are expected to be less able to persist than their wild relatives, which often have considerable dormancy and longevity, as well as effective germination cueing responses. Crop‐wild hybrids may have seed bank characteristics more suited to persistence, and maternal effects may favour persistence of hybrids having wild plants for their female parent. Escape of transgenes via crop‐wild hybrids presents unique concerns not present for crops. Hybrids can undergo natural selection and may back‐cross with wild plants. We suggest methods that can be used in conjunction with evaluation of the relative fitness of crop‐wild hybrids that will determine the likelihood of back‐crossing. Accurate assessment of escape in time and transgene persistence via crop‐wild hybrids requires proper plant materials. We emphasize the use of null segregants as controls for transgenic crops and for generating crop‐wild hybrid controls for transgenic hybrids. Since good empirical and theoretical understanding of how individual genes influence the fate of plants in different environments is lacking, evaluation of escape in time and the persistence of transgenes via crop‐wild hybrids should be on a case‐by‐case basis.
The impact of hybrids between genetically modified crop plants and their related species: general considerations
Authors: DALE P.J. 
Published: April 2008

AbstractFactors influencing the fate and impact of hybrids between crop plants and their related species operate from the early zygote, through to plant establishment in different habitats, to their ability to form self‐sustaining populations. Many of the classes of genes being introduced by modern methods of genetic modification are similar to those manipulated by conventional plant breeding. In assessing the impact of transgenes in hybrids between crops and related species, therefore, it is important to be informed about the consequences of hybridization between conventionally bred varieties and their relatives. Some transgenes will have novel effects (e.g. production of pharmaceutical substances or certain fatty acids) on plants, and are likely to need specific assessment studies to determine their impact on hybrids. This will be particularly important if there is the possibility of these transgenes becoming established in wild populations. Some recommendations for further research are outlined.
Release of transgenic plants: biodiversity and population‐level considerations
Authors: ANGLE J. SCOTT 
Published: April 2008

AbstractMany transgenic plant gene products introduced into soil are likely to degrade so quickly that they will have little impact upon the ecosystem. Some products, however, will be more recalcitrant and thus may exhibit potentially adverse effects upon the soil ecosystem. Potential changes in specific groups of organisms, functional groups of organisms and biodiversity are discussed. Methods to detect changes and the impact of changes are considered.
Assessing the impact of transgenic plant products on soil organisms
Authors: MORRA M.J. 
Published: April 2008

AbstractLittle is known about the impact of transgenic plant products on soil organisms. However, previous research with synthetic organics, allelochemicals, and extracellular enzymes can be used to guide future research in this area. Projects designed to quantify the impact of transgenic plants on soil organisms must clearly establish that the gene products are responsible for any observed changes. This can only be achieved by determining the fate of transgenic plant gene products during the period of the soil bioassay. The overall impact of transgenic plants will be dictated by not only the primary gene product, but secondary products resulting from abiotic and biotic soil reactions. Primary and secondary products may exhibit both acute and chronic impacts. Such impacts are best quantified using a soil microcosm in which fungal populations and micro‐ and mesofauna are monitored.
Transgenic plants and biogeochemical cycles
Authors: TREVORS J.T. , KUIKMAN P. , WATSON B. 
Published: April 2008

AbstractThe purpose of this manuscript is to consider interactions between transgenic (TG) plants and biogeochemical cycles, with an emphasis on how microorganisms involved in soil nutrient cycles may be influenced by transgenic plant gene products. We have also attempted to identify research areas considered a priority to fill existing information requirements on use of TG plants in the environment.
Community response to transgenic plant release: using mathematical theory to predict effects of transgenic plants
Authors: ANDOW D. A. 
Published: April 2008

AbstractPredicting the potential effects of introductions of plants on the structure of plant communities has been elusive. I suggest that mathematical models of resource competition might be useful for identifying categories of plants that either are unlikely to alter community structure or that have the potential for altering community structure. Assuming that the transgenic plant will escape and establish viable populations in nontarget habitats, this theory suggests that species that have a high minimum resource requirement are unlikely to alter community structure. The theory is elaborated to evaluate the potential effects on community structure of transgenic plants with resistance to primary consumers. Results indicate that the greatest reduction in the minimum resource requirement caused by resistance will occur when consumers are consuming enough plant biomass that the plant can no longer grow. If resistance to such a consumer were incorporated into a plant, it could lower the minimum resource requirement sufficiently that a transgenic plant would be able to alter community structure substantially. Examples of introductions of exotic plants, plant pathogens, and insect herbivores are given to support the conceptual basis of the theory. Not all transgenic plants with resistance, however, have the potential to alter community structure. Resistance to primary consumers that strongly reduce the biomass producing ability of a plant will probably be able to alter community structure, whereas resistance that reduces most other types of yield loss is less likely to alter community structure. The theory should be elaborated to incorporate more‐realistic assumptions, such as those regarding reproduction, dormancy, and dispersal of the transgenic plants, and provide more detailed characterization of the potential hazard of transgenic plants to plant communities.
Community response to transgenic plant release: predictions from British experience of invasive plants and feral crop plants
Authors: WILLIAMSON M. 
Published: April 2008

AbstractThe ten‐ten rule can be used to predict the community consequences of releasing GMOs. This, combined with data on the feral state of British crop plants, predicts that almost all GMOs will become at least casual, that more than 10% will establish, and about 10% of those will become pests. Which constructs will fall into which category cannot be predicted from their characters. In particular, Baker characters have no predictive value for weediness. The fourteen most troublesome invasive plant pests show a remarkably diverse set of characters. GMOs, being mainly derived from crop plants, and in some cases with genes that are likely to enhance survival, can be expected to have an appreciable effect on nonagricultural ecosystems, once a range of different constructs have been released. Familiarity is unlikely to be an effective defence against new ecological effects.
Test systems to determine the ecological risks posed by toxin release fromBacillus thuringiensisgenes in crop plants
Authors: JEPSON P. C. , CROFT B. A. , PRATT G. E. 
Published: April 2008

AbstractProcedures for the selection of species for ecotoxicological risk assessment ofBacillus thuringiensis(Bt) gene products in the epigeal and hypogeal environments are proposed. Although species can be selected on the basis of ecological realism and functional importance, the number of organisms requiring testing and the nature of the test procedures remain uncertain with such a selectively toxic material. The heterogeneity of the soil environment, the stratification of plant material at different stages of breakdown and decomposition and the aggregation and patterns of movement of the soil fauna and flora impose problems for the design of ecologically relevant test methods. Similarly, the impact upon beneficial invertebrates, if toxic effects are detected, will be mediated by the scale and pattern of transgenic plant release in the fragmented agricultural landscape. To properly assess the ecological risks posed by a widely released toxin with a narrow spectrum of effects, a combination of laboratory tests, field experiments and longer‐term monitoring will be required.
Parent and larval RAPD fingerprints reveal outcrossing in freshwater bryozoans
Authors: JONES C. S. , OKAMURA B. , NOBLE L. R. 
Published: April 2008

AbstractThe occurrence of outcrossing in benthic hermaphroditic colonial invertebrates has received much historical debate and little demonstration. Direct genetic study of this question using routine techniques has been limited by both the amount of material required and the detection of adequate DNA polymorphisms. However, the recent development of molecular techniques that require no a‐priori sequence data provides new approaches to the characterization of both tiny and genetically similar individuals. Random amplification of polymorphic DNA (the RAPD assay) was used to amplify fragments of DNA (via the polymerase chain reaction) to obtain fingerprints of parental colonies and larval offspring of the hermaphroditic freshwater bryozoan Cristatella mucedo. Here we report the first positive and direct genetic evidence for outcrossing in bryozoans. However, we find that outcrossing generates only low levels of genetic variation in populations that are highly clonal.
Genetic stability in a population of a plant pathogenic fungus over time
Authors: CHEN R.‐S. , BOEGER J. M. , MCDONALD B. A. 
Published: April 2008

AbstractCollections of the plant pathogenic fungus Mycosphaerella graminicola were made from the same field of wheat over a 3‐year period. The field was planted with small plots containing four varieties of wheat grown in pure stand and in all possible two‐, three‐ and four‐way mixtures. In each year, the wheat field was recolonized by a local source of inoculum of unknown origin. Allele frequencies at 10 RFLP loci were compared at two different times within a growing season and over the 3‐year period. No significant differences in allele frequencies were found for any of the RFLP loci over any of the time periods. DNA fingerprints were used to identify clones produced by asexual reproduction. Genotypic diversity based on the frequency of each clone was compared for each collection. No significant changes in genotypic diversity were found within a year or between years. Identical genotypes were found in the field at different times within a season, but no clones were conserved between years. No clone existed in a high frequency in any year, suggesting that selection for particular asexual lineages was weak. The founding population each year probably originated from wind‐borne ascospores of the teleomorph, which may exist as an indigenous population on alternative hosts, such as Poa annua (annual bluegrass).
Variation in mitochondrial DNA and population structure of the Taipei treefrog Rhacophorus taipeianus in Taiwan
Authors: YANG YI‐JU , LIN YAO‐SUNG , WU JEN‐LEIH , HUI CHO‐FAT 
Published: April 2008

AbstractMitochondrial DNA (mtDNA) from 40 samples of the Taipei treefrog Rhacophorus taipeianus collected from seven populations in Taiwan were sequenced to document the DNA sequence variation in anuran mtDNA and to elucidate the phylogeographic population structure in the Taipei treefrog. Sequences of 722–764 bases in length, including a 108‐bp segment of the cytochrome b gene and a 614–656‐bp D‐loop segment, were obtained by direct sequencing using polymerase chain reaction (PCR). The variation in length was due to a 40‐bp region that tandemly repeated four to five times in the D‐loop region. The first repeat is the most conserved one among the five repeats because there are no variable sites in this repeat. Besides the 40‐bp length variation, 28 positions in the 764‐bp sequences are variable and distributed evenly in the cytochrome b gene fragment and D‐loop region. Variation in the D‐loop of the Taipei treefrog is comparable to those of other vertebrates. Two well‐differentiated lineages (northern and central) differing by mean sequence divergence of 1.7% are identified and concordant with their geographic distributions. The two lineages are inferred to have split from a common ancestral population in the early Pleistocene. However, the interpopulation divergence of the northern lineage (< 0.33%) is apparently lower than that of the central lineage (1.11%), implying that the two lineages evolved independently and had different demographic histories after divergence. This study reveals that anuran D‐loop has potential as a genetic marker in phylogenetic and population genetic analyses of anurans.
No evidence for extrapair fertilizations in the merlin revealed by DNA fingerprinting
Authors: WARKENTIN I. G. , D.‐CURZON A. , CARTER R. E. , WETTON J. H. , JAMES P. C. , OLIPHANT L. W. , PARKIN D. T. 
Published: April 2008

AbstractBroods of young merlins were compared with the adults in attendance at their nest by DNA fingerprinting. No offspring were found that mismatched genetically suggesting that intraspecific brood parasitism and extrapair fertilization are very rare in this population. The results are discussed in the light of the Paternity Assurance Hypothesis.
Insertion sequence (IS) hybridization supports classification of Rhizobium meliloti by phage typing
Authors: BARRAN L. R. , BROMFIELD E. S. P. , LABERGE S. , WHEATCROFT R. 
Published: April 2008

AbstractSixty‐one isolates of Rhizobium meliloti from two field sites which had been previously classified into 15 phage types on the basis of sensitivity to 16 typing phages, were subjected to insertion sequence (IS) hybridization using DNA probes for ISRm3 and ISRm5. Isolates from all but one phage type contained ISRm3 (apparent copy no. 1–11) and all isolates contained ISRm5 (apparent copy no. 3–11). The isolates were placed into 24 IS classes based on differences in their respective ISRm3 and ISRm5 hybridization profiles. At either field site, isolates representing different phage types possessed IS hybridization profiles that differed from each other, while those comprising a specific type had identical or closely related profiles. Isolates from one phage type were unusual since they did not react with any of the typing phages and were shown by IS hybridization to constitute a heterogeneous group. Evidence for spatial effects were provided by isolates from two of six types present at both sites which fell into separate IS classes on the basis of their site of origin. These data have ecological implications and suggest that for a particular site, phage typing may be employed for the rapid assessment of the genetic diversity among field isolates.
DNA variability and parentage testing in captive Waldrapp ibises
Authors: SIGNER E. N. , SCHMIDT C. R. , JEFFREYS A. J. 
Published: April 2008

AbstractThe Waldrapp ibis (Geronticus eretnita) is one of the most endangered birds in the wild. The only real hope for its survival seems to rest with captive propagation, which has fortunately proved straightforward. Preservation of genetic diversity for maintaining viable populations is a major goal in any species conservation programme. Therefore sensitive tools have to be developed for the detection and regular monitoring of population variability. Individual identity has to be verified and each individual's pedigree defined in order to enable effective selective breeding. In this study, extensive DNA fingerprinting technology was applied to a group of 39 captive Waldrapp ibises. Five minisatellite probes were used. Despite the fact that the colony was founded by only six birds and that some of the founders were apparently related, highly polymorphic banding patterns were obtained. The human‐ and pig‐derived probes MS1, MS31, pλg3 and pCMS12 each detected multiple distinct loci suitable for individual identification and resolution of parentage. Probe MS51 was locus‐specific and revealed six different alleles. In addition, MS31 and pλg3 co‐detected a band present in all females but none of the males and thus could be used for sex determination. For all but four individuals both parents could be identified unambiguously. The exceptions were offspring derived from a full sib mating in which DNA results allowed no distinction between the parents and the grandparents. Comparison of the parentage assigned by DNA analysis and by observation of breeding behaviour, respectively, showed agreement in all but five instances. Here, DNA data uncovered interchange of individuals in the stud book. Application of these minisatellite probes therefore offers an extremely sensitive means for individual identification and verification and completion of pedigree records.