bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular genetics of the most endangered canid: the Ethiopian wolf Canis simensis
Authors: GOTTELLI D. , SILLERO‐ZUBIRI C. , APPLEBAUM G. D. , ROY M. S. , GIRMAN D. J. , GARCIA‐MORENO J. , OSTRANDER E. A. , WAYNE R. K. 
Published: April 2008

AbstractThe world's most endangered canid is the Ethiopian wolf Canis simensis, which is found in six isolated areas of the Ethiopian highlands with a total population of no more than 500 individuals. Ethiopian wolf populations are declining due to habitat loss and extermination by humans. Moreover, in at least one population, Ethiopian wolves are sympatric with domestic dogs, which may hybridize with them, compete for food, and act as disease vectors. Using molecular techniques, we address four questions concerning Ethiopian wolves that have conservation implications. First, we determine the relationships of Ethiopian wolves to other wolf‐like canids by phylogenetic analysis of 2001 base pairs of mitochondrial DNA (mtDNA) sequence. Our results suggest that the Ethiopian wolf is a distinct species more closely related to gray wolves and coyotes than to any African canid. The mtDNA sequence similarity with gray wolves implies that the Ethiopian wolf may hybridize with domestic dogs, a recent derivative of the gray wolf. We examine this possibility through mtDNA restriction fragment analysis and analysis of nine microsatellite loci in populations of Ethiopian wolves. The results imply that hybridization has occurred between female Ethiopian wolves and male domestic dogs in one population. Finally, we assess levels of variability within and between two Ethiopian wolf populations. Although these closely situated populations are not differentiated, the level of variability in both is low, suggesting long‐term effective population sizes of less than a few hundred individuals. We recommend immediate captive breeding of Ethiopian wolves to protect their gene pool from dilution and further loss of genetic variability.
Genetic analysis of populations of threatened snake species using RAPD markers
Authors: GIBBS H. L. , PRIOR K. A. , WEATHERHEAD P. J. 
Published: April 2008

AbstractSnakes are a particularly threatened vertebrate taxon, with distributions of many species and populations becoming increasingly fragmented. At present, little is known about the degree of genetic differentiation that exists between isolated populations even though such information may be critical to their survival and conservation. As an example of how recently developed RAPD genetic markers can be used in conservation genetics, we present preliminary results from a study which used these DNA‐based markers to assess population divergence in two threatened Canadian snakes, the black rat snake (Elaphe o. obsoleta) and the eastern massasauga rattlesnake (Sistrurus c. catenatus). We present information on the levels of variation and reliability of amplification for fragments generated from five primers. We then use a recently developed analytical technique to estimate levels of nucleotide diversity within populations and sequence divergence between populations. Our results show that intrapopulation levels of divergence as estimated by the methods of Clark & Lanigan (Molecular Biology and Evolution 1993, 10, 1096–1111) approximate those found for mtDNA in vertebrates and that diversity between snake populations is small and non‐significant when tested using randomization procedures. Thus, our study provides an example of how RAPDs can be applied to conservation genetic studies of vertebrates and suggest that the snake populations we examined have only recently become isolated and maybe considered genetically equivalent from a conservation perspective, although this conclusion needs to be confirmed with other DNA‐based markers.
Low genetic variability in a natural alpine marmot population (Marmota marmota, Sciuridae) revealed by DNA fingerprinting
Authors: RASSMANN K. , ARNOLD W. , TAUTZ D. 
Published: April 2008

AbstractGenetic heterogeneity is usually considered an important factor for the viability of a population, yet there are cases in which populations sustain themselves despite virtual homozygosity. A prior step to studying the effects of such low levels of genetic variability can be the analysis of its causes. We analysed a population of the highly social alpine marmot (Marmota marmota, Sciuridae) by multilocus DNA fingerprinting. The fingerprint patterns revealed a very low degree of polymorphism in our main study population. We show that this lack of hypervariability is caused by a low effective population size, rather than by an unusual low mutation rate of the fingerprint loci studied. However, the current number of breeding pairs was found to be about an order of magnitude larger than the one that would be expected to lead to such a low degree of heterozygosity. We conclude that there must have been bottlenecks in the history of the Berchtesgaden marmot population that have severely affected its genetic heterozygosity.
Mitochondrial DNA control region polymorphisms: genetic markers for ecological studies of marine turtles
Authors: NORMAN J. A. , MORITZ C. , LIMPUS C. J. 
Published: April 2008

AbstractWe describe a rapid and sensitive method for the detection of population‐specific genetic markers in mitochondrial DNA (mtDNA) and the use of such markers to analyse population structure of marine turtles. A series of oligonucleotide primers specific for the amplification of the mtDNA control region in Cheloniid turtles were designed from preliminary sequence data. Using two of these primers, a 384–385‐bp sequence was amplified from the 5′ portion of the mtDNA control region of 15 green turtles Chelonia mydas from 12 different Indo‐Pacific rookeries. Fourteen of the 15 individuals, including some with identical whole‐genome restriction fragment patterns, had sequences that differed by one or more base substitutions. Analysis of sequence variation among individuals identified a total of 41 nucleotide substitutions and a 1‐bp insertion/deletion. Comparison with evidence from whole‐genome restriction enzyme analysis of the same individuals indicated that this portion of the control region is evolving approximately eight times faster than the average rate and that the sequence analysis detected approximately one fifth of the total variation present in the genome. Restriction enzyme analysis of amplified products from an additional 256 individuals revealed significant geographic structuring in the distribution of mtDNA genotypes among five of the 10 rookeries surveyed extensively. Additional geographic structuring of genotypes was identified through denaturing gradient gel electrophoresis (DGGE) of amplified products. Only two of the 10 rookeries surveyed could not be differentiated, indicating that the Indo‐Pacific C. mydas include a number of genetically differentiated populations, with minimal female‐mediated gene flow among them. Important applications for genetic markers in the conservation and management of marine turtles include the identification of appropriate demographic units for research and management (i.e. genetically discrete populations) and assessment of the composition of feeding and harvested populations.
Genetic variation of the St. Lawrence beluga whale population assessed by DNA fingerprinting
Authors: PATENAUDE N. J. , QUINN J. S. , BELAND P. , KINGSLEY M. , WHITE B. N. 
Published: April 2008

AbstractRecent surveys suggest that the endangered St. Lawrence beluga (Delphinapterus leucas) population is not recovering significantly despite 20 years of protection. Dead individuals that have been autopsied show high levels of tumours and infections. This situation could be a result of pollution, loss of genetic variation, inbreeding depression or a combination of these factors. Analyses of DNA fingerprints from St. Lawrence belugas with three minisatellite probes (Jeffreys 33.6, 33.15 and M13) indicate a reduced level of genetic variation compared to Beaufort Sea animals. The average band‐sharing between individuals of the St. Lawrence beluga population for the three probes (0.534, 0.573 and 0.478, respectively) was significantly higher than that of the Beaufort Sea beluga population (0.343, 0.424, 0.314, respectively). Higher levels of mean allele frequency in the St. Lawrence belugas (0.33 vs. 0.21) suggest that this population is composed of individuals which are related. Inbreeding depression could therefore be a factor in the lack of recovery of the St. Lawrence beluga population.
Microbial diversity in soil: effect of releasing genetically engineered micro‐organisms
Authors: LEUNG K. , ENGLAND L. S. , CASSIDY M. B. , TREVORS J. T. , WEIR S. 
Published: April 2008

AbstractThis review examines the potential for change in microbial diversity, with the emphasis on bacteria, in soil resulting from the introduction of genetically engineered microorganisms (GEMs). With the advent of GEMs came the impetus for new technologies to recover these micro‐organisms from soil and to assess their effects on microbial diversity. This review also presents general aspects of and genetic approaches to accessing bacterial diversity in the environment.
Conservation genetics: beyond the maintenance of marker diversity
Authors: MILLIGAN B. G. , LEEBENS‐MACK J. , STRAND A. E. 
Published: April 2008

AbstractOne of the major problems faced by conservation biologists is the allocation of scarce resources to an overwhelmingly large number of species in need of preservation efforts. Both demographic and genetic information have been brought to bear on this problem; however, the role of information obtained from genetic markers has largely been limited to the characterization of gene frequencies and patterns of diversity. While the genetic consequences of rarity may be a contributing factor to endangerment, it is widely recognized that demographic factors often may be more important. Because patterns of genetic marker variation are influenced by the same demographic factors of interest to the conservation biologist, it is possible to extract useful demographic information from genetic marker data. Such an approach may be productive for determining plant mating systems, inbreeding depression, effective population size, and metapopulation structure. In many cases, however, data consisting only of marker frequencies are inadequate for these purposes. Development of genealogical based analytical methods coupled with studies of DNA sequence variation within and among populations is likely to yield the most information on demographic processes from genetic marker data. Indeed, in some cases it may be the only means of obtaining information on the long‐term demographic properties that may be most useful for determining the future prospects of a species of interest.
Genetic evidence for cuckoldry in bluegill Lepomis macrochirus
Authors: PHILIPP D. P. , GROSS M. R. 
Published: April 2008

AbstractIn colonies of bluegill Lepomis macrochirus, some males provide parental care for broods in nests, whereas other males steal fertilizations and do not provide parental care. Using experimental pond populations of bluegill of known genotype (determined through protein electrophoresis), we demonstrate that cuckolder males successfully fertilize eggs in parental male nests. Using electrophoretic techniques to assess the fertilization success of nesting parental male bluegill in Lake Opinicon, Ontario, we demonstrate that paternity of these males ranges from 41% to 100% among four colonies studied. This difference among colonies is related to the density of cuckolder males.
Monitoring the persistence of Laccaria bicolor as an ectomycorrhizal symbiont of nursery‐grown Douglas fir by PCR of the rDNA intergenic spacer
Authors: HENRION B. , BATTISTA C. DI , BOUCHARD D. , VAIRELLES D. , THOMPSON B. D. , TACON F. LE , MARTIN F. 
Published: April 2008

AbstractThe large‐scale inoculation of selected beneficial ectomycorrhizal fungi in forest nurseries has generated renewed interest in the ecology of these symbiotic fungi. However, information on the dissemination and persistence of introduced symbionts is scarce due to the limitation of the current identification methods. To identify ectomycorrhizal fungi on single root tips, we investigated the polymorphism of the PCR‐amplified ribosomal DNA intergenic spacer (IGS) from a wide range of ectomycorrhizal fungi. To investigate the reliability of this molecular approach in large‐scale surveys, the dissemination and persistence on Douglas fir seedlings of the introduced Laccaria bicolor S238N were assessed in a forest nursery in the Massif Central (France). Several hundred ectomycorrhizas and fruiting bodies were sampled from plots where control and L. bicolor inoculated‐Douglas fir seedlings were grown for 1.5 years. PCR typing of mycorrhizas indicated that trees inoculated with L. bicolor S238N remained exclusively colonized by that isolate (or sexually derived isolates) for the entire test period. In contrast, control seedlings were infected by indigenous isolates of Laccaria laccata and Thelephora terrestris. The molecular evidence for the persistence of the introduced mycobiont despite the competition from indigenous isolates of the same species provides further illustration of the potential of exotic species for large‐scale microbial application.
Population differentiation in randomly amplified polymorphic DNA of red‐cockaded woodpeckers Picoides borealis
Authors: HAIG S. M. , RHYMER J. M. , HECKEL D. G. 
Published: April 2008

AbstractRandom amplified polymorphic DNA (RAPD) phenotypes generated by 13 primers were scored for 101 individuals in 14 populations of the endangered red‐cockaded woodpecker Picoides borealis. Although no population‐specific markers were found, the frequencies of several markers differed significantly among populations. Application of the recently developedamova method (analysis of molecular variance; Excoffier, Smouse & Quattro 1992) showed that more than 90% of phenotypic variance occurred among individuals within populations; of the remaining variance, half was attributed among groups of geographically adjacent populations and half among populations within those groups. The statistical significance of these patterns was supported by Monte Carlo sampling simulations and permutation tests. Estimation of allele frequencies from phenotypes provided somewhat weaker evidence for population structure, although among‐population variance in allele frequencies was detectable (Fst= 0.19; x2169= 509.3, P < 0.0001). Upgma cluster analyses based on Rogers' (1972) genetic distance revealed grouping of some geographically proximate populations. A Mantel test indicated a positive (r = 0.16), although not significant, correlation between geographic and genetic distances. We compared a subset of our RAPD data with data from a previous study that used allozymes (Stangel, Lennartz & Smith 1992). RAPD (n= 75) and allozyme (n= 245) results based on samples from the same ten populations showed similar patterns. Our study indicates that RAPDs can be helpful in differentiating populations at the phenotypic level even when small sample sizes, estimation bias, and inability to test for Hardy‐Weinberg equilibrium complicate the genotypic interpretation. Lack of large differences among populations of red‐cockaded woodpeckers may allow flexibility in overpopulation translocations, provided factors such as habitat preference, latitudinal direction of translocation, and status of donor populations are considered.
Reproductive isolation and the period gene of Drosophila
Authors: RITCHIE M. G. , KYRIACOU C. P. 
Published: April 2008

AbstractThe identification of genes of large effect on ecologically important traits is an important aim of molecular ecology. The period gene of Drosophila is a candidate for a gene with a large influence on premating isolation between Drosophila species, as it determines species specific aspects of courtship behaviour. Strains of D. melanogaster are available which have been genetically transformed with the period gene of either D. melanogaster or D. simulans. Here we show that D. melanogaster females do not discriminate between two such strains. This suggests that period may only make a small contribution to total premating isolation between these species. We discuss the use of genetically transformed strains in assessing the influence of single genes on complex traits.
Transduction of a freshwater microbial community by a new Pseudomonas aeruginosa generalized transducing phage, UT1
Authors: RIPP S. , OGUNSEITAN O. A. , MILLER R. V. 
Published: April 2008

AbstractA pseudolysogenic, generalized transducing bacteriophage, UT1, isolated from a natural freshwater habitat, is capable of mediating the transfer of both chromosomal andplasmid DNA between strains of Pseudomonas aeruginosa. Several chromosomal alleles from three different P. aeruginosa strains were found to transduce at frequencies from 10‐8 to 10‐10 transductants per PFU at multiplicities of infection (MOD between 0.1 and 1. Transduction frequencies of certain alleles increased up to 1000‐fold as MOIs were decreased to 0.01. UT1 is also capable of transducing plasmid DNA to indigenous populations of microorganisms in natural lake‐water environments. Data obtained in this study suggest that environmentally endemic bacteriophages such as UT1 are formidable transducers of naturally occurring microbial communities. It should be possible to develop model systems to test transduction in freshwater environments using components derived exclusively from these environments.
Epistatic effects of promoter and repressor functions of the Tn10 tetracycline‐resistance operon on the fitness of Escherichia coli
Authors: LENSKI R. E. , SOUZA V. , DUONG L. P. , PHAN Q. G. , NGUYEN T. N. M. , BERTRAND K. P. 
Published: April 2008

AbstractWe have been studying the effects of expression of plasmid‐borne, Tn10‐encoded, tetracycline resistance on the fitness of Escherichia coli K12. We previously demonstrated large reductions in fitness resulting from induced or constitutive expression of the resistance protein; however, any residual expression by the repressed operon was so slight that possession of an inducible resistance function imposed essentially no burden in the absence of antibiotic. Here, we demonstrate two distinct disadvantages for inducible genotypes relative to isogenic constitutive constructs. During the transition from antibiotic‐free to antibiotic‐containing media, the inducible genotype experiences a longer lag phase prior to growth. In the sustained presence of antibiotic, full induction of the resistance function in the inducible genotype is prevented by the continued action of its repressor. However, these disadvantages may be reduced by increasing the strength of the promoter for the resistance gene in the inducible genotype. Simultaneous consideration of the mode of gene regulation (i.e. constitutive or inducible) and the strength of the resistance‐gene promoter (i.e. maximum level of expression) indicates an adaptive landscape with very strong epistasis and, perhaps, multiple fitness peaks.
Identification of hypervariable single locus minisatellite DNA probes in the blue tit Parus caeruleus
Authors: VERHEYEN G. R. , KEMPENAERS B. , BURKE T. , BROECK M. VAN DEN , BROECKHOVEN C. VAN , DHONDT A. 
Published: April 2008

AbstractWe report the isolation of a set of hypervariable minisatellite DNA sequences from a blue tit Parus caeruleus genomic DNA library. In our strategy, we cloned a minisatellite‐rich DNA fraction into a charomid vector. The resulting cosmid library was screened with the two minisatellite DNA probes 33.6 and 33.15 for recombinants containing a minisatellite DNA insert. A total of 233 positive clones were isolated. Of 37 clones that have been analysed, nine gave polymorphic signals and can be used as single locus probes (SLPs). Four of the SLPs were investigated in more detail. The number of alleles, the heterozygosity and the mutation rate were estimated. Linkage analysis revealed that two of these loci were linked. The SLPs are of value to studies of the mating system and reproductive success in the blue tit, and may also be useful in population genetic studies.
Quantification in soil of Bacillus thuringiensis var. kurstakiδ‐endotoxin from transgenic plants
Authors: PALM C. J. , DONEGAN K. , HARRIS D. , SEIDLER R. J. 
Published: April 2008

AbstractTransgenic plants that produce pesticidal proteins have the potential to release these products into the environment when the plants are incorporated into soil. This could result in novel exposure of soil organisms to these pesticidal proteins. There is a lack of knowledge about the fate and persistence of transgenic pesticidal products in the soil. A model system of transgenic cotton, which produces Bacillus thuringiensis kurstakiδ‐endotoxin (Bt toxin), was used to address this issue. Methods were developed to quantify Btk toxin in soil and soil/plant litter by extraction of the Btk toxin with an aqueous buffer and quantification by ELISA. The highest recovery of Btk toxin from soil was obtained with a high salt, high pH buffer. In addition, for certain soil types, addition of a non‐ionic detergent, Tween‐20, was needed for optimal recovery. Recovery of Btk toxin from soil ranged from 60% for a low clay content, low organic matter soil to 27% for a high clay content, high organic matter soil. The limit of detection of this method is 0.5 ng of extractable toxin per g dry weight soil. The method was shown to be useful in tracking over time the persistence of both purified and transgenic Btk toxin in laboratory experiments.
Fate of transformed Trichoderma harzianum in the phylloplane of tomato plants
Authors: MIGHELI Q. , HERRERA‐ESTRELLA A. , AVATANEO M. , GULLINO M. L. 
Published: April 2008

AbstractA propiconazole‐resistant Trichoderma harzianum strain with high phylloplane survival capability was transformed with the E. coli hygromycin B phosphotransferase gene (hph), coding for hygromycin B resistance. Four transformants were analysed for survival ability on the phylloplane of tomato plants grown under glasshouse conditions in comparison with their prototype and a yellow, hygromycin B‐sensitive mutant. Over 2 weeks, the four transformants showed higher survival rates in comparison with the wild‐type strain. The yellow mutant TF3/973 did not significantly differ in survival from the transformants. Both hygromycin B resistance and mitotic stability of transformants were evaluated during growth in vitro and after reisolation from tomato phylloplane. Hybridization patterns with the complete plasmid indicated that all four transformants were mitotically stable after several rounds of vegetative growth without selective pressure and during 2 weeks on tomato plants. None of the transformants had lost the ability to grow in the presence of both propiconazole and hygromycin B after growth under the same conditions. The results are discussed in relation to risk assessment of the release of transgenic fungi.