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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Characterization of messenger RNA from epimastigotes and metacyclic trypomastigotes of Trypanosoma cruzi

The cell-free translation products of polyribosomal and post-polyribosomal mRNAs from the non-infective epimastigotes and the infective metacyclic trypomastigotes of the parasitic protozoan Trypanosoma cruzi were compared by two-dimensional polyacrylamide gel electrophoresis. The result show that although many polypeptides are conserved, quantitative and qualitative differences are observed between both differentiation stages. The results also indicate the existence of post-polyribosomal mRNAs in equilibrium with polyribosomal counterparts. The immunoprecipitation of the in vitro synthesized polypeptides with chagasic human serum and the serum raised against an 85-kDa glycoprotein (P2-WGA), potentially involved in the process of T. cruzi penetration into mammalian cells, shows that while the chagasic serum recognizes the same 72-kDa, 68-kDa and 46-kDa polypeptides in both differentiation stages, the anti-P2-WGA serum immunoprecipitates a single 48-kDa polypeptide from in vitro translation products of metacyclic trypomastigotes.     

Measurements of the specific activity of the nucleoside triphosphate pool of sea-urchin embryos following 8-3H-guanosine administration

The nucleoside triphosphate (NTP) pool during the early development of sea-urchin, Paracentrotus lividus, was measured using high-performance liquid chromatography (HPLC). Each NTP pool was measured at four stages between the eight-blastomere stage and the early blastula stage, as was the specific activity of each NTP following an initial administration of 8-3H-guanosine. Unexpectedly high UTP (uridine-5'-triphosphate) concentrations and radioactivity levels in UTP were observed. Studies of the sea-urchin, Strongilocentrotus purpuratus, also revealed elevated levels of 8-3H-guanosine incorporation into UTP. The present procedure was found to be suitable for the unequivocal identification of UTP.     

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.     

GRF-induced feeding: Evidence for protein selectivity and opiate involvement

Growth hormone-releasing factor (GRF) is a hypothalamic peptide named for its ability to induce release of growth hormone from the anterior pituitary. GRF also acts as a neurotransmitter in the suprachiasmatic nucleus/medial preoptic area (SCN/MPOA) to stimulate food intake. The purpose of this series of experiments was to explore the nature of GRF-induced feeding, with a particular emphasis on macronutrient selectivity, and to examine the role of opiate activity in the paraventricular nucleus of the hypothalamus (PVN). Chow intake stimulated by GRF microinjection (1 pmol/0.5 μl) into the SCN/MPOA was blocked by injection of methyl-naltrexone (3 μg/0.5 μl) into the PVN. In animals habituated to macronutrient diets (Teklad, WI), GRF preferentially stimulated intake of protein at 2 and 4 h postinjection, whereas it had no effect on carbohydrate intake. Further, this effect was blocked by injection of naloxone (40 nmol/0.5 μl) into the PVN. Microinjection of morphine (0, 1, 10, and 17 μg/0.5 μl) into the PVN also specifically stimulated protein intake at 2 and 4 h postinjection. These results suggest that feeding derived from GRF actions in the SCN/MPOA is macronutrient selective, and is dependent on PVN opiate activity for expression.     

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.