Plant intraspecific functional trait variation is related to within‐habitat heterogeneity and genetic diversity in Trifolium montanum L.

Intraspecific trait variation (ITV), based on available genetic diversity, is one of the major means plant populations can respond to environmental variability. The study of functional trait variation and diversity has become popular in ecological research, for example, as a proxy for plant performance influencing fitness. Up to now, it is unclear which aspects of intraspecific functional trait variation (iFD_CV) can be attributed to the environment or genetics under natural conditions. Here, we examined 260 individuals from 13 locations of the rare (semi‐)dry calcareous grassland species Trifolium montanum L. in terms of iFD_CV, within‐habitat heterogeneity, and genetic diversity. The iFD_CV was assessed by measuring functional traits (releasing height, biomass, leaf area, specific leaf area, leaf dry matter content, F_v/F_m, performance index, stomatal pore surface, and stomatal pore area index). Abiotic within‐habitat heterogeneity was derived from altitude, slope exposure, slope, leaf area index, soil depth, and further soil factors. Based on microsatellites, we calculated expected heterozygosity (H_e) because it best‐explained, among other indices, iFD_CV. We performed multiple linear regression models quantifying relationships among iFD_CV, abiotic within‐habitat heterogeneity and genetic diversity, and also between separate functional traits and abiotic within‐habitat heterogeneity or genetic diversity. We found that abiotic within‐habitat heterogeneity influenced iFD_CV twice as strong compared to genetic diversity. Both aspects together explained 77% of variation in iFD_CV ( = .77, F_{2, 10} = 21.66, p < .001). The majority of functional traits (releasing height, biomass, specific leaf area, leaf dry matter content, F_v/F_m, and performance index) were related to abiotic habitat conditions indicating responses to environmental heterogeneity. In contrast, only morphology‐related functional traits (releasing height, biomass, and leaf area) were related to genetics. Our results suggest that both within‐habitat heterogeneity and genetic diversity affect iFD_CV and are thus crucial to consider when aiming to understand or predict changes of plant species performance under changing environmental conditions.     

Profiling SARS-CoV-2 HLA-I peptidome reveals T cell epitopes from out-of-frame ORFs

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Increased demand for NAD+ relative to ATP drives aerobic glycolysis

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Nanosecond fluctuations of the molecular backbone of collagen in hard and soft tissues: a carbon-13 nuclear magnetic resonance relaxation study

We have determined the amplitude of nanosecond fluctuations of the collagen azimuthal orientation in intact tissues and reconstituted fibers from an analysis of 13C NMR relaxation data. We have labeled intact rat calvaria and tibia collagen (mineralized and cross-linked), intact rat tail tendon and demineralized bone collagen (cross-linked), and reconstituted lathyritic (non-cross-linked) chick calvaria collagen with [2-13C]glycine. This label was chosen because one-third of the amino acid residues in collagen are glycine and because the 1H-13C dipolar coupling is the dominant relaxation mechanism. Spin-lattice relaxation times (T1) and nuclear Overhauser enhancements were measured at 15.09 and 62.98 MHz at 22 and -35 degrees C. The measured NMR parameters have been analyzed by using a dynamic model in which the azimuthal orientation of the molecule fluctuates as a consequence of reorientation about the axis of the triple helix. We have shown that if root mean square fluctuations in the azimuthal orientations are small, gamma rms much less than 1 rad, the correlation function decays with a single correlation time tau and T1 depends only upon tau and gamma rms and not the detailed model of motion. Our analysis shows that, at 22 degrees C, tau is in the 1-5-ns range for all samples and gamma rms is 10 degrees, 9 degrees, and 5.5 degrees for the non-cross-linked, cross-linked, and mineralized samples, respectively. At -35 degrees C, gamma rms is less than 3 degrees for all samples. These results show that mineral and low temperature significantly restrict the amplitude of nanosecond motions of the collagen backbone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biology of Elodea canadensis mich. and its management in Australian irrigation systems

The seasonal growth and decline of a population of Elodea canadensis Mich. growing in an irrigation drain are described, together with some characteristics of the aquatic environment (turbidity, photosynthetically-available radiation, temperature and pH). Overwintering buds (up to 5000 m^?2) in the form of swollen dormant stem apices are produced in autumn with the onset of cold weather, remain in the mud, and grow out in the spring. In late summer vegetative reproduction also occurs when large numbers of the leafless stem portions which are capable of growing into independent plants are swept downstream from established populations. Results suggest that control measures should be applied in early summer when populations are approaching nuisance size, and again in late summer before fragmentation occurs and overwintering propagules are initiated. In irrigation channels in Australia, where draining and drying are not feasible, biomass in successfully reduced by widespread use of herbicides.