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1.
David Skelly 《BMC biology》2010,8(1):136
A new study of divergence in freshwater fish provides strong evidence of rapid, temperature-mediated adaptation. This study
is particularly important in the ongoing debate over the extent and significance of evolutionary response to climate change
because divergence has occurred in relatively few generations in spite of ongoing gene flow and in the aftermath of a significant
genetic bottleneck, factors that have previously been considered obstacles to evolution. Climate change may thus be more likely
to foster contemporary evolutionary responses than has been anticipated, and I argue here for the importance of investigating
their possible occurrence. 相似文献
2.
Crystal structure of a berenil-dodecanucleotide complex: the role of water in sequence-specific ligand binding. 总被引:8,自引:1,他引:7 下载免费PDF全文
D G Brown M R Sanderson J V Skelly T C Jenkins T Brown E Garman D I Stuart S Neidle 《The EMBO journal》1990,9(4):1329-1334
The three-dimensional structure of a complex between the dodecanucleotide d(CGCGAATTCGCG) and the anti-trypanocidal drug berenil, has been determined to a resolution of 2.5 A. The structure has been solved by molecular replacement and refined to an R factor of 0.177. A total of 49 water molecules have been located. The drug is bound at the 5'-AAT-3' region of the oligonucleotide. At one end of the drug the amidinium group is in hydrogen-bonded contact with N3 of the adenine base complementary to the thymine of the AAT. The other amidinium group does not make direct interactions with the DNA. Instead, a water molecule mediates between them. This is in hydrogen-bonded contact with an amidinium nitrogen atom, N3 of the 5' end adenine base and the ring oxygen atom of an adjacent deoxyribose. Molecular mechanics calculations have been performed on this complex, with the drug at various positions along the sequence. These show that the observed position is only 0.8 kcal/mol higher in energy than the best position. It is suggested that there is a broad energy well in the AATT region for this drug, and that water molecules as well as the neighbouring sequence, will determine precise positioning. More general aspects of minor groove binding are discussed. 相似文献
3.
T cell responses to select Ia determinants using the I-A mutant mouse strain B6.C-H-2bm12 总被引:1,自引:0,他引:1
R R Skelly F Pappas S Koprak A Ahmed T H Hansen 《Journal of immunology (Baltimore, Md. : 1950)》1982,129(5):2094-2097
The T cell repertoire of B6.C-H-2bm12 mice (an I-A mutant mouse strain) to wild-type Iab antigens was investigated using both secondary proliferative cultures and cloned T cell lines. Because bm12 mice have a gain-loss mutation of their gene encoding the Ia beta-chain polypeptide, bm12 anti-B6 T cell responses are specific for the select component of Iab specificities that was lost as a result of the mutation. Although stimulator cells bearing Iab antigens elicited the strongest responses, Iaq, d, and s antigens also resulted in reproducible stimulations of these bm12 anti-B6-primed T cells. Cloned T cell lines isolated from bm12 anti-b6 cultures revealed similar findings, with most clones recognizing determinants unique for Iab antigens; however, clones showing cross-reactions with Iad and/or q were also selected. Using F1 hybrid responder T cells (mutant x cross-reactive strain), we further dissected this cross-reactivity into several distinct cross-reactive determinants. Because bm12 mice lack the serologically defined Ia differentiation antigen W39, T cell recognition of this determinant was investigated by using bm12 anti-B6-primed cells. Stimulation by Ia.W39+ cells was appreciably better than by Ia.W39- (Xid-defective) cells, suggesting that bm12 T cells recognize an Xid-regulated, W39-like Ia differentiation antigen. 相似文献
4.
Saturable binding of local anesthetics in rat brain homogenates was demonstrated using (14C)-lidocaine and (3H)-bupivacaine. Saturation analyses revealed a single class of binding sites for lidocaine and bupivacaine. A series of drugs with local anesthetic properties inhibited this binding, while drugs without local anesthetic activity did not affect the specific binding. Specific binding of lidocaine and bupivacaine was maximal from pH 8 to 10; the pH versus binding profile was similar to that reported for local anesthetic blocking of peripheral nerve conduction. These characteristics suggest that binding of local anesthetics to this or similar sites mediates their pharmacological activity. 相似文献
5.
A. Z. Andis Arietta L. Kealoha Freidenburg Mark C. Urban Susan B. Rodrigues Adriana Rubinstein David K. Skelly 《Ecography》2020,43(12):1791-1800
Across all taxa, amphibians exhibit some of the strongest phenological shifts in response to climate change. As climates warm, amphibians and other animals are expected to breed earlier in response to temperature cues. However, if species use fixed cues such as daylight, their breeding timing might remain fixed, potentially creating disconnects between their life history and environmental conditions. Wood frogs Rana sylvatica are a cold-adapted species that reproduce in early spring, immediately after breeding ponds are free of ice. We used long-term surveys of wood frog oviposition timing in 64 breeding ponds over 20 yr to show that, despite experiencing a warming of 0.29°C per decade in annual temperature, wood frog breeding phenology has shifted later by 2.8 d since 2000 (1.4 d per decade; 4.8 d per °C). This counterintuitive pattern is likely the result of changes in the timing of snowpack accumulation and melting. Finally, we used relationships between climate and oviposition between 2000 and 2018 to hindcast oviposition dates from climate records to model longer-term trends since 1980. Our study indicates that species can respond to fine-grained seasonal climate heterogeneity within years that is not apparent or counterintuitive when related to annual trends across years. 相似文献
6.
7.
Mark C. Urban David K. Skelly Denise Burchsted William Price Sarah Lowry 《Diversity & distributions》2006,12(4):337-350
Rapid urbanization throughout the world is expected to cause extensive loss of biodiversity in the upcoming decades. Disturbances associated with urbanization frequently operate over multiple spatial scales such that local species extirpations have been attributed both to localized habitat degradation and to regional changes in land use. Urbanization also may shape stream communities by restricting species dispersal within and among stream reaches. In this patch-dynamics view, anthropogenic disturbances and isolation jointly reduce stream biodiversity in urbanizing landscapes. We evaluated predictions of stream invertebrate community composition and abundance based on variation in environmental conditions at five distinct spatial scales: stream habitats, reaches, riparian corridors and watersheds and their spatial location within the larger three-river basin. Despite strong associations between biodiversity loss and human density in this study, local stream habitat and stream reach conditions were poor predictors of community patterns. Instead, local community diversity and abundance were more accurately predicted by riparian vegetation and watershed landscape structure. Spatial coordinates associated with instream distances provided better predictions of stream communities than any of the environmental data sets. Together, results suggest that urbanization in the study region was associated with reduced stream invertebrate diversity through the alteration of landscape vegetation structure and patch connectivity. These findings suggest that maintaining and restoring watershed vegetation corridors in urban landscapes will aid efforts to conserve freshwater biodiversity. 相似文献
8.
AB Chang NC Cox J Purcell JM Marchant PJ Lewindon GJ Cleghorn LC Ee GD Withers MK Patrick J Faoagali 《Respiratory research》2005,6(1):1-5
Background and methods
Human metapneumovirus (hMPV) is a recently discovered respiratory virus associated with bronchiolitis, pneumonia, croup and exacerbations of asthma. Since respiratory viruses are frequently detected in patients with acute exacerbations of COPD (AE-COPD) it was our aim to investigate the frequency of hMPV detection in a prospective cohort of hospitalized patients with AE-COPD compared to patients with stable COPD and to smokers without by means of quantitative real-time RT-PCR.Results
We analysed nasal lavage and induced sputum of 130 patients with AE-COPD, 65 patients with stable COPD and 34 smokers without COPD. HMPV was detected in 3/130 (2.3%) AE-COPD patients with a mean of 6.5 × 105 viral copies/ml in nasal lavage and 1.88 × 105 viral copies/ml in induced sputum. It was not found in patients with stable COPD or smokers without COPD.Conclusion
HMPV is only found in a very small number of patients with AE-COPD. However it should be considered as a further possible viral trigger of AE-COPD because asymptomatic carriage is unlikely. 相似文献9.
Variation in heat shock proteins within tropical and desert species of poeciliid fishes 总被引:8,自引:0,他引:8
Norris CE; diIorio PJ; Schultz RJ; Hightower LE 《Molecular biology and evolution》1995,12(6):1048-1062
The 70-kilodalton heat shock protein (hsp70) family of molecular
chaperones, which contains both stress-inducible and normally abundant
constitutive members, is highly conserved across distantly related taxa.
Analysis of this protein family in individuals from an outbred population
of tropical topminnows, Poeciliopsis gracilis, showed that while
constitutive hsp70 family members showed no variation in protein isoforms,
inducibly synthesized hsp70 was polymorphic. Several species of
Poeciliopsis adapted to desert environments exhibited lower levels of
inducible hsp70 polymorphism than the tropical species, but constitutive
forms were identical to those in P. gracilis, as they were in the
confamilial species Gambusia affinis. These differences suggest that
inducible and constitutive members of this family are under different
evolutionary constraints and may indicate differences in their function
within the cell. Also, northern desert species of Poeciliopsis synthesize a
subset of the inducible hsp70 isoforms seen in tropical species. This
distribution supports the theory that ancestral tropical fish migrated
northward and colonized desert streams; the subsequent decrease in
variation of inducible hsp70 may have been due to genetic drift or a
consequence of adaptation to the desert environment. Higher levels of
variability were found when the 30- kilodalton heat shock protein (hsp30)
family was analyzed within different strains of two desert species of
Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In
both cases the distribution of hsp30 isoform diversity was similar to that
seen previously with allozyme polymorphisms.
相似文献
10.
Sarunporn Tandhavanant Aunchalee Thanwisai Direk Limmathurotsakul Sunee Korbsrisate Nicholas PJ Day Sharon J Peacock Narisara Chantratita 《BMC microbiology》2010,10(1):303