Dataset Information

City limits: Heat tolerance is influenced by body size and hydration state in an urban ant community.

ABSTRACT: Cities are rapidly expanding, and global warming is intensified in urban environments due to the urban heat island effect. Therefore, urban animals may be particularly susceptible to warming associated with ongoing climate change. We used a comparative and manipulative approach to test three related hypotheses about the determinants of heat tolerance or critical thermal maximum (CT _max) in urban ants-specifically, that (a) body size, (b) hydration status, and (c) chosen microenvironments influence CT _max. We further tested a fourth hypothesis that native species are particularly physiologically vulnerable in urban environments. We manipulated water access and determined CT _max for 11 species common to cities in California's Central Valley that exhibit nearly 300-fold variation in body size. There was a moderate phylogenetic signal influencing CT _max, and inter (but not intra) specific variation in body size influenced CT _max where larger species had higher CT _max. The sensitivity of ants' CT _max to water availability exhibited species-specific thresholds where short-term water limitation (8 hr) reduced CT _max and body water content in some species while longer-term water limitation (32 hr) was required to reduce these traits in other species. However, CT _max was not related to the temperatures chosen by ants during activity. Further, we found support for our fourth hypothesis because CT _max and estimates of thermal safety margin in native species were more sensitive to water availability relative to non-native species. In sum, we provide evidence of links between heat tolerance and water availability, which will become critically important in an increasingly warm, dry, and urbanized world that others have shown may be selecting for smaller (not larger) body size.

SUBMITTER: Johnson DJ

PROVIDER: S-EPMC7297767 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

City limits: Heat tolerance is influenced by body size and hydration state in an urban ant community.

Johnson Dustin J DJ Stahlschmidt Zachary R ZR

Ecology and evolution 20200415 11

Cities are rapidly expanding, and global warming is intensified in urban environments due to the urban heat island effect. Therefore, urban animals may be particularly susceptible to warming associated with ongoing climate change. We used a comparative and manipulative approach to test three related hypotheses about the determinants of heat tolerance or critical thermal maximum (<i>CT</i> <sub>max</sub>) in urban ants-specifically, that (a) body size, (b) hydration status, and (c) chosen microen ...[more]

PMID: 32551072

Similar Datasets

Project description:BackgroundLittle is known about sex-based differences in anterior cruciate ligament (ACL) tissue quality in vivo or the association of ACL size (ie, volume) and tissue quality (ie, normalized signal intensity on magnetic resonance imaging [MRI]) with knee anatomy.HypothesisWe hypothesized that (1) women have smaller ACLs and greater ACL normalized signal intensity compared with men, and (2) ACL size and normalized signal intensity are associated with age, activity levels, body mass index (BMI), bicondylar width, intercondylar notch width, and posterior slope of the lateral tibial plateau.Study designCross-sectional study; Level of evidence, 3.MethodsKnee MRI scans of 108 unique ACL-intact knees (19.7 ± 5.5 years, 62 women) were used to quantify the ACL signal intensity (normalized to cortical bone), ligament volume, mean cross-sectional area, and length. Independent t tests were used to compare the MRI-based ACL parameters between sexes. Univariate and multivariate linear regression analyses were used to investigate the associations between normalized signal intensity and size with age, activity levels, BMI, bicondylar width, notch width, and posterior slope of the lateral tibial plateau.ResultsCompared with men, women had significantly smaller mean ACL volume (men vs women: 2028 ± 472 vs 1591 ± 405 mm3), cross-sectional area (49.4 ± 9.6 vs 41.5 ± 8.6 mm2), and length (40.8 ± 2.8 vs 38.1 ± 3.1 mm) (P < .001 for all), even after adjusting for BMI and bicondylar width. There was no difference in MRI signal intensity between men and women (1.15 ± 0.24 vs 1.12 ± 0.24, respectively; P = .555). BMI, bicondylar width, and intercondylar notch width were independently associated with a larger ACL (R 2 > 0.16, P < .001). Younger age and steeper lateral tibial slope were independently associated with shorter ACL length (R 2 > 0.03, P < .04). The combination of BMI and bicondylar width was predictive of ACL volume and mean cross-sectional area (R 2 < 0.3). The combination of BMI, bicondylar width, and lateral tibial slope was predictive of ACL length (R 2 = 0.39). Neither quantified patient characteristics nor anatomic variables were associated with signal intensity.ConclusionMen had larger ACLs compared with women even after adjusting for BMI and knee size (bicondylar width). No sex difference was observed in signal intensity, suggesting no difference in tissue quality. The association of the intercondylar notch width and lateral tibial slope with ACL size suggests that the influence of these anatomic features on ACL injury risk may be partially explained by their effect on ACL size.RegistrationNCT02292004 and NCT02664545 (ClinicalTrials.gov identifier).

Project description:Stem cell differentiation strategies and optimization for generating lineage-specific cells and tissues most frequently rely on a three-dimensional embryoid body (EB) intermediate. We previously applied nanotechnology tools of photolithography to generate custom microarrays that allow high throughput uniform formation of EBs of custom size for precise downstream analysis. Formation of EBs of 200 or 500 micron size revealed distinct morphological differences that are single or multicystic cores, respectively, independent of method of formation from single cells or two-dimensional (2D) clusters. Here we utilize photolithographic array generated EBs to obtain 3D cultures under a standardized platform for transcriptome analysis to compare EB size and the method of EB formation from single cells or mechanically passaged 2D clusters. Our analysis evaluates RNA expression in EBs formed from the human embryonic stem cell (hESC) line WA09 and from ethnically diverse human induced pluripotent stem cell lines (ED-iPSC) of African American and Hispanic Latino ethnicity recently derived in our laboratory. This is the first comprehensive study on EB transcriptomes including multiple size parameters, EB formation methodologies, and ethnicities. Our analysis indicates upregulation of genes involved in wound healing for mechanically passaged cells and of genes for embryonic tube formation in 500 micron multicystic EBs. We propose that EB maturation may be a longer process then previously realized. In addition, the type or extent of maturation possible may be influenced by EB size, with larger EBs capable of more extensive remodeling as revealed by multicystic morphology and initiation of early tube formation pathways while retaining pluripotency status. We anticipate that this information will be broadly useful to the stem cell and bioengineering communities in optimization of tissue engineering with pluripotent stem cells and understanding sources of variation. mRNA profiles by RNA-seq from embryoid bodies generated by different methods

Dataset Information

City limits: Heat tolerance is influenced by body size and hydration state in an urban ant community.

Publications

City limits: Heat tolerance is influenced by body size and hydration state in an urban ant community.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets