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1.
Hydrobiologia - Lake Malaŵi cichlids have evolved rapidly, extensively, and in some cases iteratively to fill an array of ecological niches; however, neither species richness nor trophic... 相似文献
2.
Roshan Dsouza Darold R. Spillman Ronit Barkalifa Guillermo L. Monroy Eric J. Chaney Karen C. White Stephen A. Boppart 《Journal of biophotonics》2019,12(5)
The formation of biofilms in the endotracheal tubes (ETTs) of intubated patients on mechanical ventilation is associated with a greater risk of ventilator‐associated pneumonia and death. New technologies are needed to detect and monitor ETTs in vivo for the presence of these biofilms. Longitudinal OCT imaging was performed in mechanically ventilated subjects at 24‐hour intervals until extubation to detect the formation and temporal changes of in vivo ETT biofilms. OCT‐derived attenuation coefficient images were used to differentiate between mucus and biofilm. Extubated ETTs were examined with optical and electron microscopy, and all imaging results were correlated with standard‐of‐care clinical test reports. OCT and attenuation coefficient images from four subjects were positive for ETT biofilms and were negative for two subjects. The processed and stained extubated ETTs and clinical reports confirmed the presence/absence of biofilms in all subjects. Our findings confirm that OCT can detect and differentiate between biofilm‐positive and biofilm‐negative groups (P < 10?5). OCT image‐based features may serve as biomarkers for direct in vivo detection of ETT biofilms and help drive investigation of new management strategies to reduce the incidence of VAP. 相似文献
3.
Krueger AC Madigan DL Green BE Hutchinson DK Jiang WW Kati WM Liu Y Maring CJ Masse SV McDaniel KF Middleton TR Mo H Molla A Montgomery DA Ng TI Kempf DJ 《Bioorganic & medicinal chemistry letters》2007,17(8):2289-2292
Substituted 1-hydroxy-4,4-dialkyl-3-oxo-3,4-dihydronaphthalene benzothiadiazine derivatives were investigated as inhibitors of genotype 1 HCV polymerase. Structure-activity relationship patterns for this class of compounds are discussed. It was found that the saturated alkane dialkyl units provided the most active analogs. 相似文献
4.
A sharp rise in the electrical conductance of lipid bilayer membranes was observed following the addition of antigen (bovine serum), antibody (rabbit anti-bovine serum), and complement to the neighboring aqueous phases. At low concentrations, step increases in the conductivity occurred which are consistent with the appearance of about 2.2 nm holes in the membrane. Probably attack or lysis of the lipid bilayer by complement is responsible. 相似文献
5.
Detrimental effects of a novel flow regime on the functional trajectory of an aquatic invertebrate metacommunity
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Albert Ruhi Xiaoli Dong Courtney H. McDaniel Darold P. Batzer John L. Sabo 《Global Change Biology》2018,24(8):3749-3765
Novel flow regimes resulting from dam operations and overallocation of freshwater resources are an emerging consequence of global change. Yet, anticipating how freshwater biodiversity will respond to surging flow regime alteration requires overcoming two challenges in environmental flow science: shifting from local to riverscape‐level understanding of biodiversity dynamics, and from static to time‐varying characterizations of the flow regime. Here, we used time‐series methods (wavelets and multivariate autoregressive models) to quantify flow‐regime alteration and to link time‐varying flow regimes to the dynamics of multiple local communities potentially connected by dispersal (i.e., a metacommunity). We studied the Chattahoochee River below Buford dam (Georgia, U.S.A.), and asked how flow regime alteration by a large hydropower dam may control the long‐term functional trajectory of the downstream invertebrate metacommunity. We found that seasonal variation in hydropeaking synchronized temporal fluctuations in trait abundance among the flow‐altered sites. Three biological trait states describing adaptation to fast flows benefitted from flow management for hydropower, but did not compensate for declines in 16 “loser” traits. Accordingly, metacommunity‐wide functional diversity responded negatively to hydropeaking intensity, and stochastic simulations showed that the risk of functional diversity collapse within the next 4 years would decrease by 17% if hydropeaking was ameliorated, or by 9% if it was applied every other season. Finally, an analysis of 97 reference and 23 dam‐affected river sites across the U.S. Southeast suggested that flow variation at extraneous, human‐relevant scales (12‐hr, 24‐hr, 1‐week) is relatively common in rivers affected by hydropower dams. This study advances the notion that novel flow regimes are widespread, and simplify the functional structure of riverine communities by filtering out taxa with nonadaptive traits and by spatially synchronizing their dynamics. This is relevant in the light of ongoing and future hydrologic alteration due to climate non‐stationarity and the new wave of dams planned globally. 相似文献
6.
Predation is believed to be an important natural control on larval mosquito populations. However, empirical evidence for predator impacts is lacking, especially from natural wetlands (swamps and marshes). Over a 2-year period, we sampled larval mosquito populations and naturally co-occurring predator assemblages (aquatic invertebrates, fishes) from ten depressional wetlands (Carolina bays) located on a wildlife management area in east central Georgia. We collected a diversity of mosquito larvae and predators (odonates, bugs, beetles, flies, and fishes) from the wetlands, with predator numbers substantially exceeding mosquito larval numbers. However, using a community ecology approach with multivariate ordination and correlation techniques, we found no compelling evidence that these predators were controlling mosquito larval distributions (i.e. significant negative statistical associations were not detected). Those mosquitoes that successfully breed in Carolina bay wetlands (Culiseta melanura, Coquillettidia perturbans, Anopheles crucians) appear well adapted to co-exist with a plethora of naturally occurring predators. 相似文献
7.
Krueger AC Madigan DL Beno DW Betebenner DA Carrick R Green BE He W Liu D Maring CJ McDaniel KF Mo H Molla A Motter CE Pilot-Matias TJ Tufano MD Kempf DJ 《Bioorganic & medicinal chemistry letters》2012,22(6):2212-2215
The synthesis of several pyrido[2,3-d]pyrimidine and pyrimido[4,5-d]pyrimidine analogs is described with one such analog possessing subnanomolar potency in both genotype 1a and 1b cell culture HCV replicon assays. 相似文献
8.
Krueger AC Madigan DL Jiang WW Kati WM Liu D Liu Y Maring CJ Masse S McDaniel KF Middleton T Mo H Molla A Montgomery D Pratt JK Rockway TW Zhang R Kempf DJ 《Bioorganic & medicinal chemistry letters》2006,16(13):3367-3370
Substituted N-alkyl-4-hydroxyquinolon-3-yl-benzothiadiazine sulfamides were investigated as inhibitors of genotype 1 HCV polymerase. Structure-activity relationship patterns for this class of compounds are discussed. 相似文献
9.
Lake Kronotskoye (the Kronotsky Biosphere State Reserve, south-eastern Kamchatka Peninsula) contains three closely related
resident morphotypes charrs, which are considered to be either independent species (white charr Salvelinus albus, longhead charr Salvelinus kronocius, Schmidt’s charr Salvelinus schmidti) or a united lacustrine-riverine charrs, represented by several phenotypes. Salvelinus malma malma is isolated from the lake charr populations by an upstream migration barrier in the Kronotskaya River, which flows out of
the lake. We examined the level of genetic variability and divergence of mtDNA both between charrs from Kronotsky Lake and
between resident lacustrine charrs and the hypothetical ancestor species S. m. malma. The RFLP-PCR analysis was used to examine six regions (ND1/ND2, ND3/ND4L/ND4, ND5/ND6, COI/COII/A8, A8/A6/COIII/ND3, and
Cytb/D-loop), comprising ~80% of the mtDNA. Significantly different levels of diversity were found among the populations of lacustrine
charrs. S. albus and S. schmidti had the highest indices of mtDNA diversity among the investigated populations from the different habitats. Heterogeneity
tests revealed highly significant differentiation among lake populations and among riverine (Kronotskaya River) and lake (Lake
Kronotskoye) populations of charrs, indicating their reproductive isolation. Hierarchical analysis of molecular variance revealed
the following regularities of diversity distribution: the high proportion of interpopulation variation (93.25%) and low but
statistically significant subdivision between charr populations (6.75%, P < 0.001). Results of the present study suggest that the populations of S. albus, S. kronocius, S. schmidti belong to the S. m. malma phylogenetic group. The divergence value of mtDNA of resident charrs (0.0357–0.0010%) does not exceed the intraspecific variability
of S. m. malma. The analysis of the mtDNA haplotypes genealogy of charrs showed that the low values of nucleotide divergence reflect a short
period from the beginning of divergence from the ancestral lineages and are due to ancestral polymorphism, as well as to haplotype
exchange between the diverged phylogenetic groups as a result of introgressive hybridization. 相似文献
10.
A sharp rise in the electrical conductance of lipid bilayer membranes was observed following the addition of antigen (bovine serum), antibody (rabbit anti-bovine serum), and complement to the neighboring aqueous phases. At low concentrations, step increases in the conductivity occurred which are consistent with the appearance of about 2.2 nm holes in the membrane. Probably attack or lysis of the lipid bilayer by complement is responsible. 相似文献