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1.
Calcrete aquifers from the Yilgarn region of arid central Western Australia contain an assemblage of obligate groundwater invertebrate species that are each endemic to single aquifers. Fine-scale phylogeographic and population genetic analyses of three sympatric and independently derived species of amphipod (Chiltoniidae) were carried out to determine whether there were common patterns of population genetic structure or evidence for past geographic isolation of populations within a single calcrete aquifer. Genetic diversity in amphipod mitochondrial DNA (cytochrome c oxidase subunit I gene) and allozymes were examined across a 3.5 km2 region of the Sturt Meadows calcrete, which contains a grid of 115 bore holes (=wells). Stygobiont amphipods were found to have high levels of mitochondrial haplotype diversity coupled with low nucleotide diversity. Mitochondrial phylogeographic structuring was found between haplogroups for one of the chiltoniid species, which also showed population structuring for nuclear markers. Signatures of population expansion in two of the three species, match previous findings for diving beetles at the same site, indicating that the system is dynamic. We propose isolation of populations in refugia within the calcrete, followed by expansion events, as the most likely source of intraspecific genetic diversity, due to changes in water level influencing gene flow across the calcrete. 相似文献
2.
Phylogenetic relationships were determined for 76 partial P-element
sequences from 14 species of the melanogaster species group within the
Drosophila subgenus Sophophora. These results are examined in the context
of the phylogeny of the species from which the sequences were isolated.
Sequences from the P-element family fall into distinct subfamilies, or
clades, which are often characteristic for particular species subgroups.
When examined locally among closely related species, the evolution of P
elements is characterized by vertical transmission, whereby the P-element
phylogeny traces the species phylogeny. On a broader scale, however, the
P-element phylogeny is not congruent with the species phylogeny. One
feature of P-element evolution in the melanogaster group is the presence of
more than one P-element subfamily, differing by as much as 36%, in the
genomes of some species. Thus, P elements from several individual species
are not monophyletic, and a likely explanation for the incongruence between
P-element and species phylogenies is provided by the comparison of
paralogous sequences. In certain instances, horizontal transfer seems to be
a valid alternative explanation for lack of congruence between species and
P-element phylogenies. The canonical P-element subfamily, which represents
the active, autonomous transposable element, is restricted to D.
melanogaster. Thus, its origin clearly lies outside of the melanogaster
species group, consistent with the earlier conclusion of recent horizontal
transfer.
相似文献
3.
Kenneth A. Callicott Vala Fririksdttir Jarle Reiersen Ruff Lowman Jean-Robert Bisaillon Eggert Gunnarsson Eva Berndtson Kelli L. Hiett David S. Needleman Norman J. Stern 《Applied microbiology》2006,72(9):5794-5798
Campylobacter jejuni is a major cause of bacterial food-borne infection in the industrial world. There is evidence that C. jejuni is present in eggs and hatchery fluff, opening the possibility for vertical transmission from hens to progeny. Poultry operations in Iceland provide an excellent opportunity to study this possibility, since breeding flocks are established solely from eggs imported from grandparent flocks in Sweden. This leaves limited opportunity for grandparents and their progeny to share isolates through horizontal transmission. While Campylobacter was not detected in all grandparent flocks, 13 of the 16 egg import lots consisted of eggs gathered from one or more Campylobacter-positive grandparent flocks. No evidence of Campylobacter was found by PCR in any of the 10 relevant quarantine hatchery fluff samples examined, and no Campylobacter was isolated from the parent birds through 8 weeks, while they were still in quarantine rearing facilities. After the birds were moved to less biosecure rearing facilities, Campylobacter was isolated, and 29 alleles were observed among the 224 isolates studied. While three alleles were found in both Sweden and Iceland, in no case was the same allele found both in a particular grandparent flock and in its progeny. We could find no evidence for vertical transmission of Campylobacter to the approximately 60,000 progeny parent breeders that were hatched from eggs coming from Campylobacter-positive grandparent flocks. If vertical transmission is occurring, it is not a significant source for the contamination of chicken flocks with Campylobacter spp. 相似文献
4.
The BDNF val66met polymorphism affects activity-dependent secretion of BDNF and human memory and hippocampal function 总被引:54,自引:0,他引:54
Egan MF Kojima M Callicott JH Goldberg TE Kolachana BS Bertolino A Zaitsev E Gold B Goldman D Dean M Lu B Weinberger DR 《Cell》2003,112(2):257-269
Brain-derived neurotrophic factor (BDNF) modulates hippocampal plasticity and hippocampal-dependent memory in cell models and in animals. We examined the effects of a valine (val) to methionine (met) substitution in the 5' pro-region of the human BDNF protein. In human subjects, the met allele was associated with poorer episodic memory, abnormal hippocampal activation assayed with fMRI, and lower hippocampal n-acetyl aspartate (NAA), assayed with MRI spectroscopy. Neurons transfected with met-BDNF-GFP showed lower depolarization-induced secretion, while constitutive secretion was unchanged. Furthermore, met-BDNF-GFP failed to localize to secretory granules or synapses. These results demonstrate a role for BDNF and its val/met polymorphism in human memory and hippocampal function and suggest val/met exerts these effects by impacting intracellular trafficking and activity-dependent secretion of BDNF. 相似文献
5.
Kuliszewski MA Kutryk MJ Sandhu R Fitchett D Stewart DJ 《International journal of cardiovascular interventions》2000,3(3):167-172
BACKGROUND: The NOGA (Biosense Webster, Markham, ON, Canada) injection catheter is an innovative navigational device that provides an ideal platform for intra-myocardial injection material. However, injection through a long (1.91 m), narrow (27G) nitinol needle could result in deterioration in the integrity and functionality of DNA. METHODS: To test this possibility, DNA in plasmid form (pcDNA3.1) containing the Lac Z transgene (250 micro l) was passed through the NOGA needle using a hand-held 1 cc syringe at a gentle hand injection pressure (43 +/- 3 PSI, 3.0 +/- 0.2 kg/cm(2)) or at maximal manual pressure (90 +/- 6 PSI, 6.3 +/- 0.4 kg/cm(2)), either once or 20 times. This DNA, compared to DNA not passed through the NOGA needle (control), was then used to transfect primary cultures of rat skin fibroblasts (FB) from Fisher 344 rats and the cells were subsequently stained for beta galactosidase (betagal). RESULTS: Transfection efficiency was significantly reduced by passing the DNA through the needle at both 43 +/- 3 PSI (78 +/- 4% of control, n = 10, P < 0.05 versus control) and 90 +/- 6 PSI (66 +/- 4 % of control, n = 10, P < 0.01 versus control, P < 0.02 versus 43 +/- 3 PSI). Passage of the DNA through the NOGA needle 20 times resulted in a transfection efficiency of only 5 +/- 1% of control (n = 20, P < 0.1 x 10(-11) versus control). Capillary Electrophoresis revealed that the reduction in transfection efficiency was due to a conformational change in the DNA from predominantly supercoiled to nicked and linearized DNA. Transfection efficiency as compared with control decreased as the concentration of the DNA solution which was passed through the needle was increased from 0.3 micro g/ micro l to 2.4 micro g/ micro l. Recovery experiments confirmed that the reduction in transfection efficiency was not due to loss of DNA by binding to the NOGA needle. CONCLUSION: These results suggest that DNA is susceptible to shear forces when injected through the NOGA needle even at nominal clinical injection pressures, suggesting that careful and controlled injections will be required to achieve optimal gene integrity and expression. 相似文献
6.
Callicott JB Rozzi R Delgado L Monticino M Acevedo M Harcombe P 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2007,362(1478):321-333
The perspective of 'biocomplexity' in the form of 'coupled natural and human systems' represents a resource for the future conservation of biodiversity hotspots in three direct ways: (i) modelling the impact on biodiversity of private land-use decisions and public land-use policies, (ii) indicating how the biocultural history of a biodiversity hotspot may be a resource for its future conservation, and (iii) identifying and deploying the nodes of both the material and psycho-spiritual connectivity between human and natural systems in service to conservation goals. Three biocomplexity case studies of areas notable for their biodiversity, selected for their variability along a latitudinal climate gradient and a human-impact gradient, are developed: the Big Thicket in southeast Texas, the Upper Botanamo River Basin in eastern Venezuela, and the Cape Horn Archipelago at the austral tip of Chile. More deeply, the biocomplexity perspective reveals alternative ways of understanding biodiversity itself, because it directs attention to the human concepts through which biodiversity is perceived and understood. The very meaning of biodiversity is contestable and varies according to the cognitive lenses through which it is perceived. 相似文献
7.
Real-time PCR assay for measurement of mouse telomeres 总被引:3,自引:0,他引:3
Measurement of telomeres by polymerase chain reaction (PCR) amplification has been problematic due to the formation of dimers by the primers designed to hybridize to the telomere repeats. Recently, a set of primers that overcome this problem has been created and used to develop an assay to measure human telomeres by real-time quantitative PCR. We modified this assay to measure mouse telomeres. Results showed that the primers do indeed amplify mammalian telomere repeats without forming dimers. Results obtained from the real-time quantitative PCR assay of mouse DNA were similar to terminal restriction fragment analysis by pulsed-field gel electrophoresis followed by Southern hybridization. The assay performed with mouse DNA in a similar manner as it performs with human DNA. Preliminary linkage mapping suggests a gene influencing telomere length on the X chromosome. This assay will aid in the study of telomere function and importance in diseases associated with aging and cancer formation. 相似文献
8.
J. Baird Callicott 《Journal of biosciences》2002,27(4):409-420
Classic ecological restoration seems tacitly to have taken the Clementsian “balance of nature” paradigm for granted: plant
succession terminates in a climax community which remains at equilibrium until exogenously disturbed after which the process
of succession is restarted until the climax is reached. Human disturbance is regarded as unnatural and to have commenced in
the Western Hemisphere at the time of European incursion. Classic ecological restoration thus has a clear and unambiguous
target and may be conceived as aiming to foreshorten the natural processes that would eventually lead to the climax of a given
site, which may be determined by its state at “settlement”. According to the new “flux of nature” paradigm in ecology a given
site has notelos and is constantly changing. Human disturbance is ubiquitous and long-standing, and at certain spatial and temporal scales
is “incorporated”. Any moment in the past 10,000 years that may be selected as a benchmark for restoration efforts thus appears
to be arbitrary. Two prominent conservationists have therefore suggested that the ecological conditions in North America at
the Pleistocene—Holocene boundary, prior to the anthropogenic extinction of the Pleistocene megafauna, be the target for ecological
restoration. That suggestion explicitly assumes evolutionary temporal scales and continental spatial scales as the appropriate
frame of reference for ecological restoration. However, ecological restoration should be framed in ecological spatio-temporal
scales, which may be defined temporally in reference to ecological processes such as disturbance regimes and spatially in
reference to ecological units such as landscapes, ecosystems, and biological provinces. Ecological spatio-temporal scales
are also useful in achieving a scientifically defensible distinction between native and exotic species, which plays so central
a role in the practice of ecological restoration and the conservation of biodiversity. Because post-settlement human disturbances
have exceeded the limits of such scales, settlement conditions can be justified scientifically as appropriate targets of restoration
efforts without recourse to obsolete teleological concepts of equilibria and without ignoring the presence and ecological
influence of indigenous peoples. 相似文献
9.
J Klein J Gonzalez J Duchene L Esposito JP Pradère E Neau C Delage D Calise A Ahluwalia P Carayon JB Pesquero M Bader JP Schanstra JL Bascands 《FASEB journal》2009,23(1):134-142
Renal fibrosis is the common histological feature of advanced glomerular and tubulointerstitial disease leading to end-stage renal disease (ESRD). However, specific antifibrotic therapies to slow down the evolution to ESRD are still absent. Because persistent inflammation is a key event in the development of fibrosis, we hypothesized that the proinflammatory kinin B1 receptor (B1R) could be such a new target. Here we show that, in the unilateral ureteral obstruction model of renal fibrosis, the B1R is overexpressed and that delayed treatment with an orally active nonpeptide B1R antagonist blocks macrophage infiltration, leading to a reversal of the level of renal fibrosis. In vivo bone marrow transplantation studies as well as in vitro studies on renal cells show that part of this antifibrotic mechanism of B1R blockade involves a direct effect on resident renal cells by inhibiting chemokine CCL2 and CCL7 expression. These findings suggest that blocking the B1R is a promising antifibrotic therapy. 相似文献
10.