Recent studies have highlighted both the positive and negative impacts of species invasions. Most of these studies have been conducted on either immobile invasive plants or sessile fauna found at the ...base of food webs. Fewer studies have examined the impacts of vagile invasive consumers on native competitors. This is an issue of some importance given the controlling influence that consumers have on lower order plants and animals. Here, we present results of laboratory experiments designed to assess the impacts of unintended aquaculture releases of the Nile tilapia (Oreochromis niloticus), in estuaries of the Gulf of Mexico, on the functionally similar redspotted sunfish (Lepomis miniatus). Laboratory choice tests showed that tilapia prefer the same structured habitat that native sunfish prefer. In subsequent interspecific competition experiments, agonistic tilapia displaced sunfish from their preferred structured habitats. When a piscivore (largemouth bass) was present in the tank with both species, the survival of sunfish decreased. Based on these findings, if left unchecked, we predict that the proliferation of tilapia (and perhaps other aggressive aquaculture fishes) will have important detrimental effects on the structure of native food webs in shallow, structured coastal habitats. While it is likely that the impacts of higher trophic level invasive competitors will vary among species, these results show that consequences of unintended releases of invasive higher order consumers can be important.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Bacteriophages are the most abundant members of the microbiota and have the potential to shape gut bacterial communities. Changes to bacteriophage composition are associated with disease, but how ...phages impact mammalian health remains unclear. We noted an induction of host immunity when experimentally treating bacterially driven cancer, leading us to test whether bacteriophages alter immune responses. Treating germ-free mice with bacteriophages leads to immune cell expansion in the gut. Lactobacillus, Escherichia, and Bacteroides bacteriophages and phage DNA stimulated IFN-γ via the nucleotide-sensing receptor TLR9. The resultant immune responses were both phage and bacteria specific. Additionally, increasing bacteriophage levels exacerbated colitis via TLR9 and IFN-γ. Similarly, ulcerative colitis (UC) patients responsive to fecal microbiota transplantation (FMT) have reduced phages compared to non-responders, and mucosal IFN-γ positively correlates with bacteriophage levels. Bacteriophages from active UC patients induced more IFN-γ compared to healthy individuals. Collectively, these results indicate that bacteriophages can alter mucosal immunity to impact mammalian health.
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•Bacteriophages target specific bacteria and mitigate bacterially driven colon cancer•Phages activate phage-specific and non-specific IFN-γ mediated immune responses via TLR9•Phages exacerbate colitis, and TLR9/IFNγ blockade abrogates phage-mediated inflammation•UC patient responses to fecal microbiota therapy correlate with Caurovirales abundance
Bacteriophages are abundant components of the gut microbiota, but how they impact health and immunity is unknown. Gogokhia et al. report that bacteriophages activate IFN-γ through a TLR9-dependent pathway and exacerbate colitis. Supporting this, increased abundance of bacteriophages in patients with ulcerative colitis correlates with mucosal IFN-γ responses.
This study compared the effectiveness of the Specific Carbohydrate Diet (SCD) to the Mediterranean diet (MD) as treatment for Crohn’s disease (CD) with mild to moderate symptoms.
Adult patients with ...CD and with mild-to-moderate symptoms were randomly assigned 1:1 to consume the MD or SCD for 12 weeks. For the first 6 weeks, participants received prepared meals and snacks according to their assigned diet. After 6 weeks, participants were instructed to follow the diet independently. The primary outcome was symptomatic remission at week 6. Key secondary outcomes at week 6 included fecal calprotectin (FC) response (FC <250 μg/g and reduction by >50% among those with baseline FC >250 μg/g) and C-reactive protein (CRP) response (high-sensitivity CRP <5 mg/L and >50% reduction from baseline among those with high-sensitivity CRP >5 mg/L).
The study randomized 194 patients, and 191 were included in the efficacy analyses. The percentage of participants who achieved symptomatic remission at week 6 was not superior with the SCD (SCD, 46.5%; MD, 43.5%; P = .77). FC response was achieved in 8 of 23 participants (34.8%) with the SCD and in 4 of 13 participants (30.8%) with the MD (P = .83). CRP response was achieved in 2 of 37 participants (5.4%) with the SCD and in 1 of 28 participants (3.6%) with the MD (P = .68).
The SCD was not superior to the MD to achieve symptomatic remission, FC response, and CRP response. CRP response was uncommon. Given these results, the greater ease of following the MD and other health benefits associated with the MD, the MD may be preferred to the SCD for most patients with CD with mild to moderate symptoms. ClinicalTrials.gov Identifier: NCT03058679
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During the past two decades we have gained much insight into the factors that regulate the productivity of seagrass dominated ecosystems, especially those at low latitudes. Here, we review and ...reassess the importance of plant–herbivore interactions in seagrass meadows, focusing on recent studies that have examined: 1) grazing on live seagrass leaves; 2) consumption of epiphytic algae growing on seagrass leaves; and 3) consumption of planktonic algae from the waters surrounding seagrass meadows. The major conclusion is that, in contrast to what has been reported in much of the literature on food webs in seagrass meadows, a diverse grazing pathway continues to represent an important conduit for the transfer of energy from the primary producers to higher order consumers. This remains true, although in many areas consumption of seagrasses is reduced in an historical context, owing to the overharvesting of many large species of herbivorous waterfowl, turtles and mammals.
We also summarize our view of the important gaps in understanding the broadly defined topic of herbivory in seagrass-dominated ecosystems. We suggest that future studies should focus on: understanding the foraging strategies of seagrass herbivores; quantifying the impact of herbivory on seagrass demography, including effects on sexual reproduction, the fate of flowers, and the production of fruits and seeds; and documenting the commonness of compensatory responses to grazing. In addition, the role of chemical defenses in seagrass species remains inadequately investigated. Studies of the roles of nutritional content (as measured by C/N/P ratios) and chemical defenses are also fertile grounds for future studies of epiphytes and their grazers, as are additional experiments to quantify the relative roles of top-down and bottom-up factors as they determine algal growth and abundance. There is also a need to expand the geographical scope of studies of epiphyte–grazer interactions from cold temperate to sub-tropical and tropical waters. Suspension feeders also need to be studied more broadly, with additional experiments required to quantify their effects on water clarity and their ability to fertilize pore waters, and whether benefits from these activities balances the costs of shading and competition for space that can result from both epifaunal and infaunal suspension feeders.
In the past few decades, we have learned much about the factors that regulate the productivity of seagrass-dominated ecosystems, especially those at low latitudes. Here, we update our previous ...assessments of the importance of seagrass-herbivore interactions, focusing on recent studies that have examined (1) the diversity of herbivores feeding on live seagrass leaves; (2) the factors that determine the ability of seagrasses to respond to herbivore damage; (3) how potential chemical deterrents, and structural defenses, in seagrass leaves influence herbivore consumption; (4) how climate-driven changes in herbivore identity might change grazing intensity in temperate seagrasses; (5) the effects of herbivory on pollen, flowers, fruits, and seeds of seagrasses; and (6) the effects of human removal of seagrass megaherbivores and the top-down effects of overfishing top predators on seagrass consumption. We also identify important gaps in our understanding of the broadly defined topic of herbivory in seagrass-dominated ecosystems. Specifically, we suggest that future studies should consider focusing on increasing our understanding of herbivore foraging strategies, quantifying the impact of herbivory on seagrass reproductive biology, including effects on the fates of flowers, fruits, and seeds and documenting the commonness of compensatory responses and chemical defenses to grazing. Studies of the roles of the nutritional content (as measured by C/N/P ratios), in determining herbivore feeding preferences, remain fertile grounds for future studies, as do additional experiments to quantify the relative roles of top-down and bottom-up factors in determining seagrass abundance and energy fluxes in seagrass meadows.
Pathogenic fungi reside in the intestinal microbiota but rarely cause disease. Little is known about the interactions between fungi and the immune system that promote commensalism. Here we ...investigate the role of adaptive immunity in promoting mutual interactions between fungi and host. We find that potentially pathogenic Candida species induce and are targeted by intestinal immunoglobulin A (IgA) responses. Focused studies on Candida albicans reveal that the pathogenic hyphal morphotype, which is specialized for adhesion and invasion, is preferentially targeted and suppressed by intestinal IgA responses. IgA from mice and humans directly targets hyphal-enriched cell-surface adhesins. Although typically required for pathogenesis, C. albicans hyphae are less fit for gut colonization
and we show that immune selection against hyphae improves the competitive fitness of C. albicans. C. albicans exacerbates intestinal colitis
and we demonstrate that hyphae and an IgA-targeted adhesin exacerbate intestinal damage. Finally, using a clinically relevant vaccine to induce an adhesin-specific immune response protects mice from C. albicans-associated damage during colitis. Together, our findings show that adaptive immunity suppresses harmful fungal effectors, with benefits to both C. albicans and its host. Thus, IgA uniquely uncouples colonization from pathogenesis in commensal fungi to promote homeostasis.
Background & Aims Some women with inflammatory bowel disease require therapy with tumor necrosis factor (TNF) antagonists during pregnancy. It is not clear whether these drugs are transferred to the ...fetus via the placenta and then cleared, or whether structurally different TNF antagonists have different rates of transfer. Methods We studied 31 pregnant women with inflammatory bowel disease receiving infliximab (IFX, n = 11), adalimumab (ADA, n = 10), or certolizumab (CZP, n = 10). Serum concentrations of the drugs were measured at birth in the mother, infant, and in cord blood, and then monthly in the infant until the drugs were undetectable. Drug concentrations in the cord and the infant at birth were compared with those of the mother. Results Concentrations of IFX and ADA, but not CZP, were higher in infants at birth and their cords than in their mothers. The levels of CZP in infants and their cords were less than 2 μg/mL. The median level of IFX in the cord was 160% that of the mother, the median level of ADA in the cord was 153% that of the mother, and the median level of CZP in the cord was 3.9% that of the mother. IFX and ADA could be detected in the infants for as long as 6 months. No congenital anomalies or serious complications were reported. Conclusions The TNF antagonists IFX and ADA are transferred across the placenta and can be detected in infants at birth; the drugs were detected in infants up to 6 months after birth. CZP has the lowest level of placental transfer, based on levels measured in cords and infants at birth, of the drugs tested.
Crohn's disease, a form of inflammatory bowel disease, resembles some aspects of tuberculosis, leprosy, and paratuberculosis. The role of
Mycobacterium avium subspecies
paratuberculosis(MAP) in ...Crohn's disease is controversial.
We tested for MAP by PCR and culture in buffy coat preparations from 28 individuals with Crohn's disease, nine with ulcerative colitis, and 15 without inflammatory bowel disease.
MAP DNA in uncultured buffy coats was identified by PCR in 13 (46%) individuals with Crohn's disease, four (45%) with ulcerative colitis, and three (20%) without inflammatory bowel disease. Viable MAP was cultured from the blood of 14 (50%) patients with Crohn's disease, two (22%) with ulcerative colitis, and none of the individuals without inflammatory bowel disease. Current use of immunosuppressive medication did not correlate with a positive MAP culture. Sequencing of PCR products from MAP cultures confirmed the presence of the MAP-specific IS900 fragment. Among 11 MAP isolates assessed, we identified nine strains that were not identical.
We detected viable MAP in peripheral blood in a higher proportion of individuals with Crohn's disease than in controls. These data contribute to the evidence that MAP might be a cause of Crohn's disease.
Sargramostim for Active Crohn's Disease Korzenik, Joshua R; Dieckgraefe, Brian K; Valentine, John F ...
New England journal of medicine/The New England journal of medicine,
05/2005, Letnik:
352, Številka:
21
Journal Article
Recenzirano
Odprti dostop
In this randomized trial, sargramostim (a recombinant granulocyte–macrophage colony-stimulating factor) was not significantly more likely than placebo to result in the primary outcome of a clinical ...response (a decrease from baseline of at least 70 points in the Crohn's Disease Activity Index CDAI). However, sargramostim was more likely to induce significant improvements in secondary outcome measures, including rates of remission (defined by a CDAI score of 150 or less). Injection-site reactions and bone pain were common among patients treated with sargramostim, and three patients in this group had serious adverse events.
Sargramostim (a recombinant granulocyte–macrophage colony-stimulating factor) was not significantly more likely than placebo to result in the primary outcome of a clinical response (a decrease from baseline of at least 70 points in the Crohn's Disease Activity Index).
Crohn's disease is a chronic inflammatory disorder occurring throughout the gastrointestinal tract. Current treatment emphasizes the use of immunosuppressive agents. However, evolving understanding of the pathophysiology of Crohn's disease has indicated that alternative approaches, which avoid immunosuppression, may be useful. Specifically, Crohn's disease may result from defective functioning of intestinal innate immune defense, comprising intestinal epithelium and phagocytic cells of the lamina propria, including neutrophils and macrophages. Breakdown of this defensive barrier may permit persistent exposure of lamina propria cells to luminal microbes and microbial products, resulting in an aberrant, chronic inflammatory process mediated by T cells.
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