Background and Objective
Two new T‐helper (Th) phenotypes have been recently described and named Th9 and Th22 lymphocytes; however, their role in the pathogenesis of periodontitis remains unclear. ...This study was aimed to assess whether Th9 and Th22 lymphocytes, through interleukin (IL)‐9 and IL‐22 production, respectively, are associated with the severity of periodontitis and bone resorption.
Material and Methods
Gingival crevicular fluid samples and biopsies were obtained from patients with moderate‐to‐advanced chronic periodontitis and gingivitis, and healthy controls. The levels for the Th9 and Th22‐associated cytokines and master‐switch transcription factors Spi‐B and aryl hydrocarbon receptor (AhR) were quantified by enzyme‐linked immunosorbent assay, real‐time reverse‐transcription quantitative polymerase chain reaction and flow cytometry. In addition, the osteoclast activity in response to tissue homogenates from periodontitis and healthy samples was analyzed quantifying the number of TRAP‐positive cells and areas of bone resorption pits produced, in the presence or absence of recombinant human IL‐22 and anti‐IL‐22 neutralization antibody.
Results
Higher levels of IL‐22 and AhR were detected in patients with periodontitis compared with gingivitis and healthy individuals. In addition, higher levels of IL‐9 and Spi‐B were detected in gingivitis patients compared with periodontitis and healthy individuals. In patients with periodontitis, a significant positive correlation was detected between secreted levels of IL‐22 and clinical attachment level of the sampled periodontal pockets. When osteoclasts were exposed to tissue homogenates obtained from patients with periodontitis, higher levels of resorptive activity were observed as compared with the same cells exposed to tissue homogenates obtained from healthy individuals, and this increment was dependent on the presence and neutralization of IL‐22.
Conclusion
Increased levels of IL‐22 produced by Th22 lymphocytes are associated with the pathogenesis of periodontitis, in particular, with osteoclast resorptive activity and severity of disease.
In viviparous fishes, females of species that exhibit matrotrophy (post‐fertilization maternal provisioning to developing embryos) and superfetation (ability of females to bear simultaneously ...multiple broods of embryos at distinct developmental stages) increase less in mass and volume during pregnancy than females of species that lack these traits. Such a reduction in reproductive allocation may provide greater benefits to young and small females for two reasons. First, they could devote energy and resources to both growth and reproduction. Second, they could compensate for the space restrictions that are inherent to a small body size because both superfetation and matrotrophy maximize fecundity for any given ovarian volume. In this study, we test the hypothesis that both matrotrophy and superfetation will decrease over female reproductive lifespan (i.e. as they grow larger). We examined reproductive females from 77 populations of 13 species of the family Poeciliidae. Remarkably, we found support for the matrotrophy prediction in only three populations. As expected, in these populations, small females were more matrotrophic than larger females, which in turn exhibited a predominantly lecithotrophic strategy. In one population, we found the opposite pattern—the degree of matrotrophy actually increased in larger females. With respect to superfetation, none of the populations showed a pattern consistent with our prediction. In fact, in five populations the pattern was opposite to our expectation—larger females produced more simultaneous broods than smaller females. Our findings reveal that the degree of matrotrophy and superfetation can vary throughout the adult lifespans of poeciliid fishes, but such ontogenetic shifts are not common in natural populations.
In this study, we test the hypothesis that both matrotrophy and superfetation will decrease over female reproductive lifespan (i.e. as they grow larger). We examined reproductive females from 77 populations of 13 species of the family Poeciliidae. Our findings reveal that the degree of matrotrophy and superfetation can vary throughout the adult lifespans of poeciliid fishes, but such ontogenetic shifts are not common in natural populations. Photo credit: Ana Laura Hernández‐Rosas
Exotic species pose a threat to most ecosystems because of their potential to establish negative interactions with native biota. However, exotic species can also offer resources to native species, ...especially within highly modified environments such as urban ecosystems. We studied 17 exotic-native pairs of species with the potential to compete with one another, or in which one of the species could offer resources to the other, in an urban ecological reserve located within Mexico City. We used two-species occupancy models to analyze the potential association between the presence of the exotic species and the spatial distribution of the native species, as well as to assess if these species tend to avoid each other (negative spatial interaction) or to co-occur more often than expected under the hypothesis of independent occurrences (positive spatial interaction). Our results revealed few cases in which the exotic species influenced occupancy of the native species, and these spatial interactions were mainly positive, indicated by the fact that the occupancy of the native species was usually higher when the exotic species was also present. Seven of the eight observed non-independent patterns of co-occurrence were evident during the dry months of the year, when resources become scarce for most species. Our results also demonstrate that the observed patterns of species co-occurrence depend on the distance to the nearest urban structure and the amount of herb, shrub, and tree cover, indicating that these habitat features influence whether native species avoid or co-occur with exotic species. Our study represents an important contribution to the understanding of temporal dynamics in the co-occurrence between exotic and native species within urban ecological reserves.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Key Takeaways
Traditional drought risk measures can be unreliable and inefficient; machine learning can do better by learning from the data and establishing hidden connections and patterns.
Machine ...learning models can help water systems determine their vulnerabilities to drought.
Developing a machine learning model should be a collaborative process among data scientists, domain experts, and decision makers.
Accurate calculations of the double proton transfer (DPT) in the adenine−thymine base pair (AT) were presented in a previous work J. Phys. Chem. A 2009, 113, 7892. where we demonstrated that the ...mechanism of the reaction in solution is strongly affected by surrounding water. Here we extend our methodology to the guanine−cytosine base pair (GC), for which it turns out that the proton transfer in the gas phase is a synchronous concerted mechanism. The O(G)−H−N(C) hydrogen bond strength emerges as the key parameter in this process, to the extent that complete transfer takes place by means of this hydrogen bond. Since the main effect of the molecular environment is precisely to weaken this bond, the direct proton transfer is not possible in solution, and thus the tautomeric equilibrium must be assisted by surrounding water molecules in an asynchronous concerted mechanism. This result demonstrates that water plays a crucial role in proton reactions. It does not act as a passive element but actually catalyzes the DPT.
A
bstract
The ANTARES neutrino telescope has an energy threshold of a few tens of GeV. This allows to study the phenomenon of atmospheric muon neutrino disappearance due to neutrino oscillations. In ...a similar way, constraints on the 3+1 neutrino model, which foresees the existence of one sterile neutrino, can be inferred. Using data collected by the ANTARES neutrino telescope from 2007 to 2016, a new measurement of Δ
m
32
2
and
θ
23
has been performed — which is consistent with world best-fit values — and constraints on the 3+1 neutrino model have been derived.
Methionine adenosyltransferases MAT I and MAT III (encoded by Mat1a) catalyze S-adenosylmethionine synthesis in normal liver. Major hepatic diseases concur with reduced levels of this essential ...methyl donor, which are primarily due to an expression switch from Mat1a towards Mat2a. Additional changes in the association state and even in subcellular localization of these isoenzymes are also detected. All these alterations result in a reduced content of the moderate (MAT I) and high Vmax (MAT III) isoenzymes, whereas the low Vmax (MAT II) isoenzyme increases and nuclear accumulation of MAT I is observed. These changes derive in a reduced availability of cytoplasmic S-adenosylmethionine, together with an effort to meet its needs in the nucleus of damaged cells, rendering enhanced levels of certain epigenetic modifications. In this context, the putative role of protein-protein interactions in the control of S-adenosylmethionine synthesis has been scarcely studied. Using yeast two hybrid and a rat liver library we identified PDRG1 as an interaction target for MATα1 (catalytic subunit of MAT I and MAT III), further confirmation being obtained by immunoprecipitation and pull-down assays. Nuclear MATα interacts physically and functionally with the PDRG1 oncogene, resulting in reduced DNA methylation levels. Increased Pdrg1 expression is detected in acute liver injury and hepatoma cells, together with decreased Mat1a expression and nuclear accumulation of MATα1. Silencing of Pdrg1 expression in hepatoma cells alters their steady-state expression profile on microarrays, downregulating genes associated with tumor progression according to GO pathway analysis. Altogether, the results unveil the role of PDRG1 in the control of the nuclear methylation status through methionine adenosyltransferase binding and its putative collaboration in the progression of hepatic diseases.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Competition has long been recognized as a central force in shaping evolution, particularly through character displacement. Yet research on character displacement is biased, as it has focused almost ...exclusively on pairs of interacting species while ignoring multispecies interactions. Communities are seldom so simple that only pairs of species interact, and it is not clear whether inferences from pairwise interactions are sufficient to explain patterns of phenotypes in nature. Here, we test for character displacement in a natural system of freshwater fishes in western Mexico that contains up to four congeneric species of the genus Poeciliopsis. We analyzed body shape differences between populations with different numbers of competitors while accounting for confounding environmental variables. Surprisingly, we found evidence for convergent character displacement in populations of P. prolifica, P. viriosa, and P. latidens. We also found that the convergence in body shape was not consistently in the same direction, meaning that when three or more competitors co-occurred, we did not find more extreme body shapes compared with when there were only two competitors. Instead, when three or more competitors co-occurred, body shape was intermediate between the shape found with a pair of species and the shape found with no competitor present. This intermediate shape suggests that evolution in multispecies communities likely occurs in response to several competitors rather than to simple pairwise interactions. Overall, our results suggest that competition among multiple species is more complex than simple pairwise competitive interactions.
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