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Abstract Glucocorticoids contribute to the daily migration patterns of T cells in well-nourished organisms and are elevated in the malnourished. We examined the effect of malnutrition on T cell migration by comparing the migration patterns of adoptively transferred malnourished and control T cells in the lymphoid organs of malnourished and control recipients. We found that malnourished T cells generally entered lymphoid tissues more efficiently than control T cells, regardless of recipient. Strikingly, the bone marrow of malnourished recipients attracted naïve malnourished T cells, but not control T cells, more efficiently than control bone marrow. In contrast, the spleens of malnourished and control mice attracted similar numbers of naïve T cells. Further experiments revealed that T cells residing in the bone marrow of malnourished mice express higher levels of CCR7 and lower levels of CD11a than control T cells. We also examined the effect of T cell-specific deficiency of the glucocorticoid receptor on T cell migration to the bone marrow in malnourished mice. Indeed, similarly low percentages of glucocorticoid receptor deficient T cells were observed in the bone marrow of malnourished and control mice, indicating that T cell expression of the glucocorticoid receptor is required for T cell migration to the bone marrow. Overall, we have determined that malnutrition modifies both the bone marrow and naïve T cells to promote naïve T cell migration to the bone marrow and that at least the T cell-specific effects are mediated via the glucocorticoid receptor.
NSF-MRI [DBI- 1920116] NSF-RUI [IOS-1951881]
Free, publicly-accessible full text available May 1, 2024 -
Weed community structure, including composition, taxonomic and functional diversity, may explain variability in crop quality, adding to the variability accounted by management, climatic and genetic factors. Focusing on Mediterranean rainfed wheat crops, we sampled weed communities from 26 fields in Spain that were either organically or conventionally managed. Weed communities were characterized by their abundance and taxonomic, compositional and trait-based measures. Grain protein concentration and the glutenin to gliadin ratio were used as indicators of wheat grain quality. Linear mixed effects models were used to analyze the relationship between crop quality and weed community variables, while accounting for environmental factors. Nitrogen fertilization, previous crop and precipitation explained a large portion of the variation in wheat grain protein concentration (R2marginal = 0.39) and composition (R2marginal = 0.26). Weed community measures had limited effects on grain quality (increasing R2marginal of models by 1% on average). The weed effects were related to the composition and the functional structure of their communities, but not to their abundance. Environmental conditions promoting higher protein concentration were also selecting for weed species with competitive attributes, whereas the role of weed functional diversity depended on the functional trait and on the resource limiting crop grain quality. Understanding the mechanisms of weed effects on crop quality could aid on designing sustainable weed management practices.more » « less
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Urban green space, comprising parks, fields, woodlands, and other semi-natural areas, is a fundamental component of urban ecosystems. The determination of the relationship between urban green space and urban sprawl is necessary to understand urbanization and the provision of urban ecosystem services. It has been hypothesized that the center of urban (i.e., population and economic) areas in fast-growing cities would migrate toward urban green space over time. To test this hypothesis, urban expansion and urban green space expansion were examined in five cities in China and five cities in the U.S. that were experiencing high rates of growth. Landsat images of those cities from 2000 to 2017 were combined with annual population and economic data and used to quantify the extent and migration of the urban green space. These data were analyzed using the center of gravity method by Grether and Mathys and circular statistics were used to determine the relationship between urban green space and urban expansion. Eight out of the ten cities showed a divergent pattern, i.e., the population and economic centers moved in a different direction to that of the urban green space. The movement of the mean centers of the urban green spaces in the U.S. cities was more consistent than that of the Chinese cities. Over 18 years, the movement of urban green space and urban expansion in the 10 cities showed a synchronous growth trend; however, the proportion of urban green space in the cities decreased. The urban expansion rate exceeded the population growth rate, which led to problems with an unreasonable urban sprawl that is likely to deplete the provision of ecosystem services in the future. In conclusion, the centrifugal forces of urban green space that lead to the movement of population and economic centers away from green spaces play a larger role in urban change than the centripetal forces that pull these centers toward urban green space.more » « less
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Abstract Malnutrition is associated with reductions in the number and function of T lymphocytes. Previous studies in the lab suggest that malnutrition may also impart a “super-quiescent” phenotype to T cells, perhaps affecting the efficiency of their migration within and between lymph nodes. Thus, the purpose of this study is to evaluate the effect of malnutrition on T cell migration in vivo and to characterize malnutrition-induced changes in the expression of proteins known to be important for T cell migration. To determine if malnourishment alters T cell migration in vivo, we compared lymph node entry rates of adoptively-transferred malnourished and control T cells in malnourished and control recipients. In agreement with other studies, control CD4+ T cells were more efficient than control CD8+ T cells at entering the lymph nodes. Interestingly, regardless of recipient diet, malnourished CD4+ and CD8+ T cells entered the lymph nodes at equivalent rates, suggesting that malnourishment eliminates distinct lymph node entry efficiencies for CD8+ and CD4+ T cells. We also found important differences in the expression of key proteins involved in T cell migration between malnourished and control mice. Overall, we found that malnutrition disrupts T cell migration including the distinct migration efficiencies of CD4+ and CD8+ T cells. An improved understanding of T cell-intrinsic changes that occur during malnourishment should enhance our knowledge of CD4+ and CD8+ T cell migration and shed light on how organisms adapt to malnutrition. Supported by NSF-MRI [DBI- 1920116] NSF-RUI [IOS-1951881]more » « less
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Abstract Previous work suggests that glucocorticoids upregulate expression of CD127, an IL-7 receptor component, on peripheral naïve T cells (NT), even though the total number of peripheral NT declines dramatically during malnourishment. We proposed that CD127 up-regulation contributes to peripheral NT reduction by increasing the scavenge rate of IL-7, providing a mechanism to rapidly adjust the total number of NTs during malnutrition. Each malnourished NT would then receive a larger dose of IL-7 than control NTs. We next wondered if this larger dose might confer additional energy-saving behaviors. NT migration across HEV’s may be a high energy-consuming activity. Thus, we compared lymph node entry rates of adoptively-transferred malnourished and control NT in malnourished and control recipients. Control CD4+ NTs migrated more efficiently than control CD8+ NT, but malnourished CD4+ and CD8+ NT migrated at equivalent rates, regardless of recipient diet. We next analyzed expression of proteins known to be involved in NT migration to uncover the currently unknown mechanisms responsible for these various migration patterns. Flow cytometry analysis revealed malnutrition significantly reduces expression of both components of LFA-1 (CD18 and CD11a), CD49d (a VLA-4 component), and S1PR1 in CD4+ and CD8+ NT. We also compared expression levels of ICAM-1 (CD54), a protein expressed in HEV’s which binds to LFA-1 on migrating NT, in malnourished and control lymph node tissue via confocal microscopy. Improved understanding of altered migration molecule expression during malnourishment should enhance our knowledge of the energy-conserving behavior of NT, as well as uncover strategies to improve vaccination responses in malnourished children.more » « less
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Abstract Local adaptation is a fundamental phenomenon in evolutionary biology, with relevance to formation of ecotypes, and ultimately new species, and application to restoration and species’ response to climate change. Reciprocal transplant gardens, a common garden in which ecotypes are planted among home and away habitats, are the gold standard to detect local adaptation in populations.
This review focuses on reciprocal transplant gardens to detect local adaptation, especially in grassland species beginning with early seminal studies of grass ecotypes. Fast forward more than half a century, reciprocal gardens have moved into the genomic era, in which the genetic underpinnings of ecotypic variation can now be uncovered. Opportunities to combine genomic and reciprocal garden approaches offer great potential to shed light on genetic and environmental control of phenotypic variation. Our decadal study of adaptation in a dominant grass across the precipitation gradient of the US Great Plains combined genomic approaches and realistic community settings to shed light on controls over phenotype.
Common gardens are not without limitations and challenges. A survey of recent studies indicated the modal study uses a tree species, three source sites and one growing site, focuses on one species growing in a monoculture, lasts 3 years, and does not use other experimental manipulations and rarely employs population genetic tools. Reciprocal transplant gardens are even more uncommon, accounting for only 39% of the studies in the literature survey with the rest occurring at a single common site. Reciprocal transplant gardens offer powerful windows into local adaptation when (a) placed across wide environmental gradients to encompass the species’ range; (b) conducted across timespans adequate for detecting responses; (c) employing selection studies among competing ecotypes in community settings and (d) combined with measurements of form and function which ultimately determine success in home and away environments.
Synthesis . Reciprocal transplant gardens have been one of the foundations in evolutionary biology for the study of adaptation for the last century, and even longer in Europe. Moving forward, reciprocal gardens of foundational non‐model species, combined with genomic analyses and incorporation of biotic factors, have the potential to further revolutionize evolutionary biology. These field experiments will help to predict and model response to climate change and inform restoration practices. -
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Abstract Aims The productivity–plant diversity relationship is a central subject in ecology under debate for decades. Anthropogenic disturbances have been demonstrated to affect productivity and plant diversity. However, the impact of disturbances on the productivity–diversity relationship is poorly understood.
Location An old‐field located at the Touch of Nature Environmental Center in Jackson County, Illinois, USA.
Methods A manipulative experiment with fertilizer (unfertilized, fertilized annually, fertilized every five years) and mowing (unmowed, mowed in spring only, mowed in spring and fall) in a successional old‐field began in 1996 to examine disturbance effects on above‐ground net primary productivity (ANPP)–plant diversity relationships. Taxonomic (species richness, T0) and phylogenetic (net relatedness index, NRI) diversity were selected as potential plant diversity metrics.
Results A unimodal relationship of ANPP with T0 and a negative relationship between ANPP and NRI were found across all treatments and years in this study, but individual years showed different patterns. Fertilization did not affect T0, NRI, and ANPP, whereas mowing stimulated T0 and ANPP but reduced NRI (i.e., increasing phylogenetic diversity) across all survey years. New colonists, especially exotic species introduced under mowing, but not locally extinct species, were more distantly related to resident species than by chance, implying that invasion of exotic species contributes to phylogenetic overdispersion of community assembly in the old‐field. However, the patterns of the unimodal relationship of ANPP with T0 and the negative correlation between ANPP and NRI did not change under fertilization or mowing in this study.
Conclusions Anthropogenic disturbances alter productivity and different dimensions of plant diversity, but do not change the patterns of the productivity–diversity relationships. Our findings highlight the robust relationship between productivity and diversity providing empirical support for productivity as a powerful predictor of plant diversity under intensified human activities.
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Abstract Dominant species can act as a biotic filter in structuring plant communities by constraining the establishment and survival of subordinate species. The effect of intraspecific trait variability of dominant species on the functional response of subordinate species, however, is not well understood.
We quantified intraspecific variation in four functional traits of 26 subordinate species in an experimental grassland established with two population sources (i.e. cultivars and local ecotypes) of three dominant grasses (
Sorghastrum nutans, Andropogon gerardii andSchizachyrium scoparium ) and three pools of subordinate species (each from one origin) within each of the dominant grass source treatments.Twenty of the 26 subordinate species exhibited intraspecific trait variability for one trait or more in response to dominant species population source, and variation among population sources of the dominant species was non‐random. Dominant grass population source affected intraspecific variability in functional traits of multiple subordinate species. Cultivar sources of the dominant grasses and some of the subordinate species that established with them had higher and generally more variable functional leaf area and leaf nitrogen content compared to local ecotypes of the dominant grasses and the subordinate species that established with them. Local ecotype sources of the dominant grasses increased leaf area based functional diversity of subordinate species.
Synthesis. This study provides evidence that intraspecific trait variability in dominant species acts as a biotic filter to constrain niche availability and dimensionality affecting trait variation of subordinate species during community assembly.
