Clonally derived bacterial populations exhibit significant genotypic and phenotypic diversity that contribute to fitness in rapidly changing environments. Here, we show that serial passage of ...Salmonella enterica serovar Typhimurium LT2 (StLT2) in broth, or within a mouse host, results in selection of an evolved population that inhibits the growth of ancestral cells by direct contact. Cells within each evolved population gain the ability to express and deploy a cryptic "orphan" toxin encoded within the rearrangement hotspot (rhs) locus. The Rhs orphan toxin is encoded by a gene fragment located downstream of the "main" rhs gene in the ancestral strain StLT2. The Rhs orphan coding sequence is linked to an immunity gene, which encodes an immunity protein that specifically blocks Rhs orphan toxin activity. Expression of the Rhs orphan immunity protein protects ancestral cells from the evolved lineages, indicating that orphan toxin activity is responsible for the observed growth inhibition. Because the Rhs orphan toxin is encoded by a fragmented reading frame, it lacks translation initiation and protein export signals. We provide evidence that evolved cells undergo recombination between the main rhs gene and the rhs orphan toxin gene fragment, yielding a fusion that enables expression and delivery of the orphan toxin. In this manner, rhs locus rearrangement provides a selective advantage to a subpopulation of cells. These observations suggest that rhs genes play important roles in intra-species competition and bacterial evolution.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Palaeoecology involves analysis of fossil and sub-fossil evidence preserved within sediments to understand past species distributions, habitats and ecosystems. However, while palaeoecological ...research is sometimes made relevant to contemporary ecology, especially to advance understanding of biogeographical theory or inform habitat-based conservation at specific sites, most ecologists do not routinely incorporate palaeoecological evidence into their work. Thus most cross-discipline links are palaeoecology → ecology rather than ecology → palaeoecology. This is likely due to lack of awareness and/or the misnomer that palaeoecology invariably relates to the “distant past” (thousands of years) rather than being applicable to the “recent past” (last ~ 100–200 years). Here, we highlight opportunities for greater integration of palaeoecology within contemporary ecological research, policy, and practice. We identify situations where palaeoecology has been, or could be, used to (1) quantify recent temporal change (e.g. population dynamics; predator–prey cycles); (2) “rewind” to a particular point in ecological time (e.g. setting restoration/rewilding targets; classifying cryptogenic species); (3) understand current ecological processes that are hard to study real-time (e.g. identifying keystone species; detecting ecological tipping points); (4) complement primary data and historical records to bridge knowledge gaps (e.g. informing reintroductions and bioindicator frameworks); (5) disentangle natural and anthropogenic processes (e.g. climate change); and (6) draw palaeoecological analogues (e.g. impacts of pests). We conclude that the possibilities for better uniting ecology and palaeoecology to form an emerging cross-boundary paradigm are as extensive as they are exciting: we urge ecologists to learn from the past and seek opportunities to extend, improve, and strengthen their work using palaeoecological data.
The Little Ice Age (LIA) is a well-recognised palaeoclimatic phenomenon, although its causes, duration and severity have been matters of debate and dispute. Data from a wide range of archives have ...been used to infer climate variability before, during and after the LIA. Some published proxy-climate data from peatlands imply that two particularly severe episodes within the LIA may be contemporaneous between hemispheres; these echo a previous climatic downturn ca. 2800 cal BP of similar severity but lesser duration. Here, we present palaeoclimate data from the mid- to late-Holocene, reconstructed from three blanket peats in Yorkshire: Mossdale Moor, Oxenhope Moor and West Arkengarthdale. Multiproxy techniques used for palaeoclimatic reconstruction were plant macrofossil, pollen and humification analyses. Dating was provided by a radiocarbon-based chronology, aided by spheroidal carbonaceous particles (SCPs) for all sites, and 210Pb dates for one. The LIA presents as a distinct climatic event within each palaeoenvironmental record at the three sites. These indications are compared with terrestrial datasets from northwest Europe and elsewhere. A broad degree of synchronicity is evident, signifying that the LIA is one of the most pronounced downturns in global climate in the last ca. 6000 years, and arguably the most routinely recorded within the Holocene.
The magnitude and quality of the germinal center (GC) response decline with age, resulting in poor vaccine-induced immunity in older individuals. A functional GC requires the co-ordination of ...multiple cell types across time and space, in particular across its two functionally distinct compartments: the light and dark zones. In aged mice, there is CXCR4-mediated mislocalization of T follicular helper (T
) cells to the dark zone and a compressed network of follicular dendritic cells (FDCs) in the light zone. Here we show that T
cell localization is critical for the quality of the antibody response and for the expansion of the FDC network upon immunization. The smaller GC and compressed FDC network in aged mice were corrected by provision of T
cells that colocalize with FDCs using CXCR5. This demonstrates that the age-dependent defects in the GC response are reversible and shows that T
cells support stromal cell responses to vaccines.
Plant cell growth and stress signaling require Ca²⁺ influx through plasma membrane transport proteins that are regulated by reactive oxygen species. In root cell growth, adaptation to salinity ...stress, and stomatal closure, such proteins operate downstream of the plasma membrane NADPH oxidases that produce extracellular Superoxide anion, a reactive oxygen species that is readily converted to extracellular hydrogen peroxide and hydroxyl radicals, OH˙ In root cells, extracellular OH˙ activates a plasma membrane Ca²⁺ -permeable conductance that permits Ca²⁺ influx. In Arabidopsis thaliana, distribution of this conductance resembles that of annexin1 (ANN1). Annexins are membrane binding proteins that can form Ca²⁺ -permeable conductances in vitro. Here, the Arabidopsis loss-of-function mutant for annexin1 (Atann1) was found to lack the root hair and epidermal OH˙-activated Ca²⁺ -and K⁺ -permeable conductance. This manifests in both impaired root cell growth and ability to elevate root cell cytosolic free Ca²⁺ in response to OH˙. An OH˙-activated Ca²⁺ conductance is reconstituted by recombinant ANN1 in planar lipid bilayers. ANN1 therefore presents as a novel Ca²⁺-permeable transporter providing a molecular link between reactive oxygen species and cytosolic Ca²⁺ in plants.
There have been significant advancements in risk identification and treatment for ovarian cancer over the last decade. However, their impact on health services costs is unclear. This study estimated ...the direct health system costs (government perspective) for women diagnosed with ovarian cancer in Australia during 2006-2013, as a benchmark prior to opportunities for precision-medicine approaches to treatment, and for health care planning.
Using cancer registry data, we identified 176 incident ovarian cancers (including fallopian tube and primary peritoneal cancer) in the Australian 45 and Up Study cohort. Each case was matched with four cancer-free controls on sex, age, geography, and smoking history. Costs were derived from linked health records on hospitalisations, subsidised prescription medicines and medical services to 2016. Excess costs for cancer cases were estimated for different phases of care relative to cancer diagnosis. Overall costs for prevalent ovarian cancers in Australia in 2013 were estimated based on 5-year prevalence statistics.
At diagnosis, 10% of women had localised disease, 15% regional spread and 70% distant metastasis (5% unknown). The mean excess cost per ovarian cancer case was $40,556 in the initial treatment phase (≤12 months post-diagnosis), $9,514 per annum in the continuing care phase and $49,208 in the terminal phase (up to 12 months before death). Hospital admissions accounted for the greatest proportion of costs during all phases (66%, 52% and 68% respectively). Excess costs were higher for patients diagnosed with distant metastatic disease, particularly during the continuing care phase ($13,814 versus $4,884 for localised/regional disease). The estimated overall direct health services cost of ovarian cancer in 2013 was AUD$99million (4,700 women nationally).
The excess health system costs of ovarian cancer are substantial. Continued investment in ovarian cancer research, particularly prevention, early detection and more effective personalised treatments is necessary to reduce the burden of disease.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
Mounting evidence from human studies suggests that bile acid dysmetabolism might play a role in various human chronic gastrointestinal diseases. It is unknown whether fecal bile acid ...dysmetabolism occurs in dogs with chronic inflammatory enteropathy (CE).
Objective
To assess microbial dysbiosis, fecal unconjugated bile acids (fUBA), and disease activity in dogs with steroid‐responsive CE.
Animals
Twenty‐four healthy control dogs and 23 dogs with steroid‐responsive CE.
Methods
In this retrospective study, fUBA were measured and analyzed. Fecal microbiota were assessed using a dysbiosis index. The canine inflammatory bowel disease activity index was used to evaluate remission of clinical signs. This was a multi‐institutional study where dogs with steroid‐responsive CE were evaluated over time.
Results
The dysbiosis index was increased in dogs with CE (median, 2.5; range, −6.2 to 6.5) at baseline compared with healthy dogs (median, −4.5; range, −6.5 to −2.6; P = .002) but did not change in dogs with CE over time. Secondary fUBA were decreased in dogs with CE (median, 29%; range, 1%‐99%) compared with healthy dogs (median, 88%; 4%‐96%; P = .049). The percent of secondary fUBA in dogs with CE increased from baseline values (median, 28%; range, 1%‐99%) after 2‐3 months of treatment (median, 94%; range, 1%‐99%; P = 0.0183).
Conclusions and Clinical Importance
These findings suggest that corticosteroids regulate fecal bile acids in dogs with CE. Additionally, resolution of clinical activity index in dogs with therapeutically managed CE and bile acid dysmetabolism are likely correlated. However, subclinical disease (i.e., microbial dysbiosis) can persist in dogs with steroid‐responsive CE.
In 2018, the giant manta ray was listed as threatened under the U.S. Endangered Species Act. We integrated decades of sightings and survey effort data from multiple sources in a comprehensive species ...distribution modeling (SDM) framework to evaluate the distribution of giant manta rays off the eastern United States, including the Gulf of Mexico. Manta rays were most commonly detected at productive nearshore and shelf-edge upwelling zones at surface thermal frontal boundaries within a temperature range of approximately 20-30 °C. SDMs predicted highest nearshore occurrence off northeastern Florida during April, with the distribution extending northward along the shelf-edge as temperatures warm, leading to higher occurrences north of Cape Hatteras, North Carolina from June to October, and then south of Savannah, Georgia from November to March as temperatures cool. In the Gulf of Mexico, the highest nearshore occurrence was predicted around the Mississippi River delta from April to June and again from October to November. SDM predictions will allow resource managers to more effectively protect manta rays from fisheries bycatch, boat strikes, oil and gas activities, contaminants and pollutants, and other threats.
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