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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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.     

TonB protein and energy transduction between membranes

TonB protein couples cytoplasmic membrane electrochemical potential to active transport of iron-siderophore complexes and vitamin B12 through high-affinity outer membrane receptors of Gram-negative bacteria. The mechanism of energy transduction remains to be determined, but important concepts have already begun to emerge. Consistent with its function, TonB is anchored in the cytoplasmic membrane by its uncleaved amino terminus while largely occupying the periplasm. Both the connection to the cytoplasmic membrane and the amino acid sequences of the anchor are essential for activity. TonB directly associates with a number of envelope proteins, among them the outer membrane receptors and cytoplasmic membrane protein ExbB. ExbB and TonB interact through their respective transmembrane domains. ExbB is proposed to recycle TonB to an active conformation following energy transduction to the outer membrane. TonB most likely associates with the outer membrane receptors through its carboxy terminus, which is required for function. In contrast, the novel prolinerich region of TonB can be deleted without affecting function. A model that incorporates this information, as well as tempered speculation, is presented.     

Measuring ligament elasticity of the knee joint--elasticity measuring strip and its alternatives]

Those techniques for measuring ligament tension at the knee joint that are most commonly cited and easiest to carry out are discussed. These include four techniques based on the use of strain gauges. Apart from the Omega transducer and the buckle transducer, there is also the tendon force transducer, and the application of strain gauges to the bony ligament insertion sites. Other indirect measuring methods considered are the mercury strain transducer and the Hall effect transducer. The parameter measured with all of these methods is fluctuating current or voltage, which is then correlated with ligament tension. Three direct measurements are also discussed: the separation distances of marked fibres of the ligaments, replacement of fibres by threads, and a load cell/bone plug construction. The measured value is equated with the effective change in ligament length.     

Fine structural recognition specificities of IgE antibodies distinguishing amoxicilloyl and amoxicillanyl determinants in allergic subjects.

IgE antibodies in the sera of subjects allergic to beta-lactam antibiotics detect a spectrum of specificities ranging from side-chain groups to an entire penicillin or cephalosporin molecule. In addition to such structural heterogeneity of allergenic determinants, IgE antibodies in the sera of different allergic subjects show heterogeneous recognition responses. Detailed immunochemical studies were carried out on the sera of penicillin-allergic subjects that showed selective and unexpected reactions with the frequently prescribed penicillin, amoxicillin. Antibodies from one subject reacted only with the amoxicilloyl determinant while IgE from another subject showed multiple reactivity with penicilloyl and penicillanyl determinants of different penicillins but not with the amoxicilloyl determinant. Quantitative hapten inhibition studies revealed that the combining sites of the former antibodies were complementary to amoxicillin in a form that permits binding to the hydroxyaminobenzyl side-chain and the thiazolidine ring carboxyl. These conditions are satisfied with the drug in the '-oyl' but not in the '-anyl' form which involves linkage through the 2-carboxyl of the thiazolidine ring. With the second serum, adsorption studies showed that the wide-ranging reactivity of IgE was due to a single population of antibodies that detected a common specificity on the different penicillins. Combining site studies revealed clear recognition of the benzyl portion of the side-chain of benzylpenicilloyl, benzylpenicillanyl, ampicilloyl, ampicillanyl and amoxicillanyl determinants when free antibody access to the side-chain was possible but little or no recognition of the ring hydroxyl of amoxicillin. Such uninhibited access may not occur, however, when amoxicillin is conjugated in the '-oyl' form since opening the beta-lactam ring allows increased flexibility and rotation of the molecule and the possibility of close association of the hydroxyaminobenzyl side-chain of amoxicillin with the linked peptide carrier. In such close steric association, H-bonding involving the ring hydroxyl and amino acids of the carrier may prevent antibody access to the side-chain region of the amoxicilloyl determinant.