Several phenomenological descriptions, such as the von Bertalanffy growth model, have been widely used to describe size-at-age and individual growth across a diverse range of organisms. However, for modelling life histories, as opposed to just growth, biologically and mechanistically meaningful growth models, based on allocation decisions, have become increasingly important. This is because fitness is determined by survival and reproduction, which are not addressed directly in phenomenological growth models. To elucidate these considerations, we take as a starting point the biphasic growth model by Quince et al. (2008a, J. Theor. Biol. 254:197) which has the advantage that the underlying allometric scaling of net energy intake can be freely chosen. First, we reformulate this model such that individual size is given in meaningful units of length and weight, facilitating the model׳s interpretation and application. Second, we show that even though different allometric scaling relationships can produce practically identical growth trajectories, the accompanying reproductive investments are highly dependent on the chosen allometric exponent. Third, we demonstrate how this dependence has dramatic consequences for evolutionary predictions, in particular with regard to the age and size at maturation. These findings have considerable practical relevance, because empirically observed allometric exponents are often uncertain and systematically differ from those assumed in current standard growth models.

• MeSH
• druhová specificita MeSH
• genetická zdatnost MeSH
• lidé MeSH
• přežití MeSH
• rozmnožování fyziologie   MeSH
• růst fyziologie   MeSH
• tělesné váhy a míry * MeSH
• teoretické modely * MeSH
• velikost těla * MeSH
• životní prostředí MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

It has been widely reported that men have a lower ratio of the 2nd and 4th human finger lengths (2D : 4D). Size-scaling ratios, however, have the seldom-appreciated potential for providing biased estimates. Using an information-theoretic approach, we compared 12 candidate models, with different assumptions and error structures, for scaling untransformed 2D to 4D lengths from 154 men and 262 women. In each hand, the two-parameter power function and the straight line with intercept models, both with normal, homoscedastic error, were superior to the other models and essentially equivalent to each other for normalizing 2D to 4D lengths. The conventional 2D : 4D ratio biased relative 2D length low for the generally bigger hands of men, and vice versa for women, thereby leading to an artefactual indication that mean relative 2D length is lower in men than women. Conversely, use of the more appropriate allometric or linear regression models revealed that mean relative 2D length was, in fact, greater in men than women. We conclude that 2D does not vary in direct proportion to 4D for both men and women, rendering the use of the simple 2D : 4D ratio inappropriate for size-scaling purposes and intergroup comparisons.

• MeSH
• antropometrie MeSH
• lidé MeSH
• lineární modely MeSH
• pohlavní dimorfismus * MeSH
• prsty ruky anatomie a histologie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

The surface area-to-volume ratio of cells is one of the key factors affecting fundamental biological processes and, thus, fitness of unicellular organisms. One of the general models for allometric increase in surface-to-volume scaling involves fractal-like elaboration of cellular surfaces. However, specific data illustrating this pattern in natural populations of the unicellular organisms have not previously been available. This study shows that unicellular green algae of the genus Micrasterias (Desmidiales) have positive allometric surface-to-volume scaling caused by changes in morphology of individual species, especially in the degree of cell lobulation. This allometric pattern was also detected within most of the cultured and natural populations analysed. Values of the allometric S:V scaling within individual populations were closely correlated to the phylogenetic structure of the clade. In addition, they were related to species-specific cellular morphology. Individual populations differed in their allometric patterns, and their position in the allometric space was strongly correlated with the degree of allometric S:V scaling. This result illustrates that allometric shape patterns are an important correlate of the capacity of individual populations to compensate for increases in their cell volumes by increasing the surface area. However, variation in allometric patterns was not associated with phylogenetic structure. This indicates that the position of the populations in the allometric space was not evolutionarily conserved and might be influenced by environmental factors.

• MeSH
• fylogeneze MeSH
• Micrasterias klasifikace   cytologie   genetika   MeSH
• regresní analýza MeSH
• RNA ribozomální 18S genetika   MeSH
• velikost buňky MeSH
• Publikační typ
• časopisecké články MeSH

Ratios often lead to biased conclusions concerning the actual relationships between examined traits and comparisons of the relative size of traits among groups. Therefore, the use of ratios has been abandoned in most comparative studies. However, ratios such as body mass index and waist-to-hip ratio are widely used in evolutionary biology and medicine. One such, the ratio of the 2nd to the 4th finger (2D : 4D), has been the subject of much recent interest in both humans and animals. Most studies agree that 2D : 4D is sexually dimorphic. In men, the 2nd digit tends to be shorter than the 4th, while in women the 2nd digit tends to be of the same size or slightly longer than the 4th. Nevertheless, here we demonstrate that the sexes do not greatly differ in the scaling between the 2nd and 4th digit. Sexual differences in 2D : 4D are mainly caused by the shift along the common allometric line with non-zero intercept, which means 2D : 4D necessarily decreases with increasing finger length, and the fact that men have longer fingers than women. We conclude that previously published results on the 2D : 4D ratio are biased by its covariation with finger length. We strongly recommend regression-based approaches for comparisons of hand shape among different groups.

• MeSH
• lidé MeSH
• pohlavní dimorfismus MeSH
• prsty ruky anatomie a histologie   MeSH
• toxoplazmóza epidemiologie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• práce podpořená grantem MeSH
• srovnávací studie MeSH

Background and Aims: Below-ground carbohydrate storage is considered an adaptation of plants aimed at regeneration after disturbance. A theoretical model by Iwasa and Kubo was empirically tested which predicted (1) that storage of carbohydrates scales allometrically with leaf biomass and (2) when the disturbance regime is relaxed, the ratio of storage to leaf biomass increases, as carbohydrates are not depleted by disturbance. Methods: These ideas were tested on nine herbaceous species from a temperate meadow and the disturbance regime was manipulated to create recently abandoned and mown plots. Just before mowing in June and at the end of the season in October, plants with below-ground organs were sampled. The material was used to assess the pool of total non-structural carbohydrates and leaf biomass. Key Results: In half of the cases, a mostly isometric relationship between below-ground carbohydrate storage and leaf biomass in meadow plants was found. The ratio of below-ground carbohydrate storage to leaf biomass did not change when the disturbance regime was less intensive than that for which the plants were adapted. Conclusions: These findings (isometric scaling relationship between below-ground carbohydrate storage and leaf biomass; no effect of a relaxed disturbance regime) imply that storage in herbs is probably governed by factors other than just the disturbance regime applied once in a growing season.

• MeSH
• biomasa * MeSH
• ekosystém * MeSH
• listy rostlin fyziologie   MeSH
• Magnoliopsida fyziologie   MeSH
• metabolismus sacharidů * MeSH
• pastviny MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH

BACKGROUND: Although absolute handgrip strength has been associated with health-related outcomes in older adults, little evidence has been provided regarding its adjustment by a variety of body size dimensions. Therefore, the main purpose of the study was to establish the most appropriate normalization of handgrip strength by different body size parameters in a large sample of noninstitutionalized older adults. METHODS: In this cross-sectional study, we enrolled 643 men and women aged > 60, who were part of the rehabilitation center facility program. Handgrip strength was objectively measured using a Jamar Plus* + Digital Hand Dynamometer. Body size parameters included body weight and height, body mass index, waist circumference, waist-to-height ratio, fat mass and fat-free mass. The most appropriate parameter associated with handgrip strength was identified using allometry. RESULTS: Findings showed that the most appropriate body size parameter for handgrip strength normalization was height (allometric exponent: 0.85), compared to fat-free mass (0.26) and body mass (0.12). Other body size variables were not significantly associated with handgrip strength and were omitted from further analyses. The correlations between normalized handgrip strength were significant when handgrip strength was normalized by body mass and fat-free mass, while no significant correlations were found, when handgrip strength was normalized by body height. CONCLUSION: Based on the study results, body height seems to be the best body size parameter for handgrip strength normalization in older adults, omitting the influence of body size on strength performance. If handgrip strength is measured, body height may help normalize strength for large-scale research.

• Publikační typ
• časopisecké články MeSH

Recent studies indicate that yawning evolved as a brain cooling mechanism. Given that larger brains have greater thermolytic needs and brain temperature is determined in part by heat production from neuronal activity, it was hypothesized that animals with larger brains and more neurons would yawn longer to produce comparable cooling effects. To test this, we performed the largest study on yawning ever conducted, analyzing 1291 yawns from 101 species (55 mammals; 46 birds). Phylogenetically controlled analyses revealed robust positive correlations between yawn duration and (1) brain mass, (2) total neuron number, and (3) cortical/pallial neuron number in both mammals and birds, which cannot be attributed solely to allometric scaling rules. These relationships were similar across clades, though mammals exhibited considerably longer yawns than birds of comparable brain and body mass. These findings provide further evidence suggesting that yawning is a thermoregulatory adaptation that has been conserved across amniote evolution.

• MeSH
• mozek anatomie a histologie   fyziologie   MeSH
• neurony cytologie   fyziologie   MeSH
• ptáci anatomie a histologie   fyziologie   MeSH
• savci anatomie a histologie   fyziologie   MeSH
• velikost orgánu MeSH
• zívání * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Isoxazolines are oral insecticidal drugs currently licensed for ectoparasite control in companion animals. Here we propose their use in humans for the reduction of vector-borne disease incidence. Fluralaner and afoxolaner rapidly killed Anopheles, Aedes, and Culex mosquitoes and Phlebotomus sand flies after feeding on a drug-supplemented blood meal, with IC50 values ranging from 33 to 575 nM, and were fully active against strains with preexisting resistance to common insecticides. Based on allometric scaling of preclinical pharmacokinetics data, we predict that a single human median dose of 260 mg (IQR, 177-407 mg) for afoxolaner, or 410 mg (IQR, 278-648 mg) for fluralaner, could provide an insecticidal effect lasting 50-90 days against mosquitoes and Phlebotomus sand flies. Computational modeling showed that seasonal mass drug administration of such a single dose to a fraction of a regional population would dramatically reduce clinical cases of Zika and malaria in endemic settings. Isoxazolines therefore represent a promising new component of drug-based vector control.

• MeSH
• Culicidae růst a vývoj   MeSH
• insekticidy farmakologie   MeSH
• komáří přenašeči růst a vývoj   MeSH
• kontrola infekčních nemocí metody   MeSH
• lidé MeSH
• moskyti - kontrola metody   MeSH
• Psychodidae růst a vývoj   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This study presents a systematic review conducted according to the PRISMA 2020 guidelines, evaluating pharmacokinetic-pharmacodynamic (PK-PD) models for target-controlled infusion (TCI) of propofol. A structured search was performed across PubMed, Summon, Google Scholar, Web of Science, and Scopus, identifying 427 sources, of which 17 met the inclusion criteria. The analysis revealed that nine studies compared existing models, six focused on the development of new PK-PD models, and two explored broader implications of TCI in anesthesia. Comparative studies indicate that while the Eleveld model generally offers superior predictive accuracy, it does not consistently outperform the Marsh and Schnider models across all populations. The Schnider model demonstrated better bias control in elderly patients, while the Eleveld model improved drug clearance estimation in obese patients. However, inconsistencies remain in predicting brain concentrations of propofol. Newly proposed models introduce adaptive dosing strategies, incorporating allometric scaling, lean body weight, and machine learning techniques, yet require further external validation. The results highlight ongoing challenges in achieving universal applicability of TCI models, underscoring the need for future research in refining precision dosing and personalized anesthesia management.

• MeSH
• anestetika intravenózní * aplikace a dávkování   farmakokinetika   farmakologie   MeSH
• biologické modely MeSH
• intravenózní infuze MeSH
• lidé MeSH
• propofol * aplikace a dávkování   farmakokinetika   farmakologie   MeSH
• strojové učení MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• systematický přehled MeSH

Alders (Alnus spp.) often dominate at nutrient-poor sites by symbiotic relations with atmospheric nitrogen-fixing bacteria. However, little is known about quantitative relationships between root nodule as a nitrogen acquisition organ and leaf as a carbon acquisition organ. To examine carbon allocation, nitrogen acquisition and net production in nutrient-poor conditions, we examined allocation patterns among organs of shrub Alnus fruticosa at a young 80-year-old moraine in Kamchatka. Slopes of double-log allometric equations were significantly smaller than 1.0 for the root mass, leaf mass and root nodule mass against stem mass, and for the root nodule mass against root mass, indicating that smaller individuals invested disproportionally more biomass into resource-acquiring leaf and root tissues than to supportive tissues compared to older individuals. The slope of allometric equation of root depth against stem height was 0.542, indicating that smaller/younger individuals allocate disproportionally more biomass into root length growth than stem height growth. On the contrary, the root nodule mass isometrically scaled to leaf mass. The whole-plant nitrogen content also isometrically scaled to root nodule mass, indicating that a certain ratio of nitrogen acquisition depended on root nodules, irrespective of plant size. Although the net production per plant increased with the increase in stem mass, the slope of the double-log regression was smaller than 1.0. On the contrary, the net production per plant isometrically increased with leaf mass, root nodule mass and leaf nitrogen content per plant. Since the leaf mass isometrically scaled to root nodule mass, growth of each individual occurred at the leaves and root nodules in a coordinated manner. It is suggested that their isometric increase contributes to the increase in net production per plant for A. fruticosa in nutrient-poor conditions.

• MeSH
• biomasa MeSH
• dusík metabolismus   MeSH
• kořenové hlízky rostlin růst a vývoj   fyziologie   MeSH
• kořeny rostlin růst a vývoj   fyziologie   MeSH
• ledový příkrov MeSH
• olše růst a vývoj   fyziologie   MeSH
• stonky rostlin růst a vývoj   fyziologie   MeSH
• symbióza MeSH
• uhlík metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Rusko MeSH