Quantify Growth Rates Research Articles

Heartwood Relationship with Stem Diameter in Pinus canariensis Plantations of Gran Canaria, Spain

The development of stem heartwood and the factors that control it play an important role in tree physiology, thereby impacting demographic and ecological processes of woody species. We investigated the relationships of stem heartwood with site- and tree-level variables in Pinus canariensis plantations. A total of 30 plots were sampled in the island of Gran Canaria, Spain, over a large elevation range (995–1875 m) and on terrain with different slopes (4%–70%) and exposures. The 15 pines closest to each plot center were measured and cored to quantify growth rates and the size of heartwood, also known as “tea”. We used generalized linear mixed models (GLMMs) to account for both fixed and random effects while evaluating the best predictors of heartwood presence. Stem diameter was the variable most correlated with heartwood radius, and allowing for a random slope and intercept of this relationship accounted for spatially related variability. Furthermore, the GLMM model became more effective when the relationship between stem diameter and heartwood was modeled using the presence/absence of the “tea” rather than its measured size. Other site- and tree-level variables either were not statistically significant or improved the model relatively little. Because stem heartwood affects both wood quality and the amount of carbon that trees can store, our findings have implications for forest management and carbon-conscious policies.

Modeling of zircon nucleation and growth rates using crystal size distributions in a cooling magmatic intrusion

With a rapid increase in the use of zircons for geochronology and in situ isotopic and chemical analyses it is important to quantify growth rates and nucleation rates of zircons in natural magmatic systems. Here we present a mathematical model of the nucleation and growth of a population of zircon crystals in a cooling magmatic intrusion and apply nucleation laws to derive zircon crystal size distributions (CSD) and particle number density (n per cm3 of melt) from first principles. The model is based on a numerical solution of the one-dimensional diffusion equation that accounts for the nucleation and growth of individual crystals and the dependence of the equilibrium concentration of Zr on temperature. As experimental studies of zircon nucleation at natural concentration levels of Zr are nearly impossible, we rely on measured CSDs of age-invariant (within error of the method <±5ky) zircon populations in rapidly quenched eruptive products of known crystallization duration to calibrate our model. The CSDs of zircon crystals are calculated at different rates of cooling of the magma chamber and are compared to measurements. The combination of the zircon growth software with measurements of zircon CSDs and particle number density permits direct estimation of the zircon nucleation rates and their evolution with time in cooling magmatic systems. We observe a delayed zircon nucleation of 500–2000 years after the melt becomes zircon saturated. Zr supersaturations that drive grown in simulations range from 1 to ∼30ppm and vary non-monotonically as crystallization proceeds. Initially, the nucleation rates increase exponentially from 10−3 to ∼1crystals/cm3/yr but then decrease by an order of magnitude as the distance between zircons decreases. Growth rates stay in 10−15cm/s range for the most duration of zircon growth. The ratio of growth to nucleation rates in our model also varies insignificantly and is used to estimate crystallization time based on the CSD slope, which decreases with the increased duration of cooling. Flatter slopes correspond to longer crystallization durations as is also noted for major phases. Due to non-monotonic variations in growth and nucleation rates with time, the observed deficiency of small zircons resulting in concave up CSD shapes can be reproduced from first principles assuming monotonic cooling of the magmatic system. Variations in the mode of cooling from linear to monotonic during conductive heat loss of a cooling intrusion, and minor coeval precipitation (<10vol%) of major phases has little impact on zircon CSD and its evolution. This study has implication to individual zircons IDTIMS dates and demonstrates that most zircons crystallize much later than magma becomes saturated with Zr, despite sometimes having nominally long tail crystallization rate in the inherited cores. For natural CSDs from eight different eruptions randomly selected zircons predate eruption age only by ∼300–1000years.

Quantitative Analysis of Aspergillus nidulans Growth Rate using Live Microscopy and Open-Source Software.

It is well established that colony growth of filamentous fungi, mostly dependent on changes in hyphae/mycelia apical growth rate, is macroscopically estimated on solidified media by comparing colony size. However, to quantitatively measure the growth rate of genetically different fungal strains or strains under different environmental/growth conditions (pH, temperature, carbon and nitrogen sources, antibiotics, etc.) is challenging. Thus, the pursuit of complementary approaches to quantify growth kinetics becomes mandatory in order to better understand fungal cell growth. Furthermore, it is well-known that filamentous fungi, including Aspergillus spp., have distinct modes of growth and differentiation under sub-aerial conditions on solid media or submerged cultures. Here, we detail a quantitative microscopic method for analyzing growth kinetics ofthe model fungus Aspergillus nidulans, using live imaging in both submerged cultures and solid media. We capture images, analyze, and quantify growth rates of different fungal strains in a reproducible and reliable manner using an open source, free software for bio-images (e.g., Fiji), in a way that does not require any prior image analysis expertise from the user.

3D Scanning as a Tool to Measure Growth Rates of Live Coral Microfragments Used for Coral Reef Restoration

Rapid and widespread declines in coral health and abundance have driven increased investments in coral reef restoration interventions to jumpstart population recovery. Microfragmentation, an asexual propagation technique, is used to produce large numbers of corals for research and restoration. As part of resilience-based restoration, coral microfragments of different genotypes and species are exposed to various stressors to identify candidates for propagation. Growth rate is one of several important fitness-related traits commonly used in candidate selection, and being able to rapidly and accurately quantify growth rates of different genotypes is ideal for high-throughput stress tests. Additionally, it is crucial, as coral restoration becomes more commonplace, to establish practical guidelines and standardized methods of data collection that can be used across independent groups. Herein, we developed a streamlined workflow for growth rate quantification of live microfragmented corals using a structured-light 3D scanner to assess surface area (SA) measurements of live tissue over time. We then compared novel 3D and traditional 2D approaches to quantifying microfragment growth rates and assessed factors such as accuracy and speed. Compared to a more conventional 2D approach based on photography and ImageJ analysis, the 3D approach had comparable reliability, greater accuracy regarding absolute SA quantification, high repeatability, and low variability between scans. However, the 2D approach accurately measured growth and proved to be faster and cheaper, factors not trivial when attempting to upscale for restoration efforts. Nevertheless, the 3D approach has greater capacity for standardization across dissimilar studies, making it a better tool for restoration practitioners striving for consistent and comparable data across users, as well as for those conducting networked experiments, meta-analyses, and syntheses. Furthermore, 3D scanning has the capacity to provide more accurate surface area (SA) measurements for rugose, mounding, or complex colony shapes. This is the first protocol developed for using structured-light 3D scanning as a tool to measure growth rates of live microfragments. While each method has its advantages and disadvantages, disadvantages to a 3D approach based on speed and cost may diminish with time as interest and usage increase. As a resource for coral restoration practitioners and researchers, we provide a detailed 3D scanning protocol herein and discuss its potential limitations, applications, and future directions.

StalGrowth—A Program to Estimate Speleothem Growth Rates and Seasonal Growth Variations

Speleothems are one of the few archives which allow us to reconstruct the terrestrial paleoclimate and help us to understand the important climate dynamics in inhabited regions of our planet. Their time of growth can be precisely dated by radiometric techniques, but unfortunately seasonal radiometric dating resolution is so far not feasible. Numerous cave environmental monitoring studies show evidence for significant seasonal variations in parameters influencing carbonate deposition (calcium-ion concentration, cave air pCO2, drip rate and temperature). Variations in speleothem deposition rates need to be known in order to correctly decipher the climate signal stored in the speleothem archive. StalGrowth is the first software to quantify growth rates based on cave monitoring results, detect growth seasonality and estimate the seasonal growth bias. It quickly plots the predicted speleothem growth rate together with the influencing cave environmental parameters to identify which parameter(s) cause changes in speleothem growth rate, and it can also identify periods of no growth. This new program has been applied to multiannual cave monitoring studies in Austria, Gibraltar, Puerto Rico and Texas, and it has identified two cases of seasonal varying speleothem growth.

In-vivo 3D imaging of Zebrafish’s intersegmental vessel development by a bi-directional light-sheet illumination microscope

Precise quantification of vascular developments in Zebrafish requires continuous in-vivo 3D imaging. Here we employed a bi-directional light-sheet illumination microscope to characterize the development process of Zebrafish’s intersegmental vessels. A Virtual Reality-based method was used to measure the lengths of intersegmental vessels (ISVs). The quantified growth rates of typical ISVs can be plotted, and unusual growth of some specific vessels was also observed.

A simplified strategy for titrating gene expression reveals new relationships between genotype, environment, and bacterial growth.

A lack of high-throughput techniques for making titrated, gene-specific changes in expression limits our understanding of the relationship between gene expression and cell phenotype. Here, we present a generalizable approach for quantifying growth rate as a function of titrated changes in gene expression level. The approach works by performing CRISPRi with a series of mutated single guide RNAs (sgRNAs) that modulate gene expression. To evaluate sgRNA mutation strategies, we constructed a library of 5927 sgRNAs targeting 88 genes in Escherichia coli MG1655 and measured the effects on growth rate. We found that a compounding mutational strategy, through which mutations are incrementally added to the sgRNA, presented a straightforward way to generate a monotonic and gradated relationship between mutation number and growth rate effect. We also implemented molecular barcoding to detect and correct for mutations that ‘escape’ the CRISPRi targeting machinery; this strategy unmasked deleterious growth rate effects obscured by the standard approach of ignoring escapers. Finally, we performed controlled environmental variations and observed that many gene-by-environment interactions go completely undetected at the limit of maximum knockdown, but instead manifest at intermediate expression perturbation strengths. Overall, our work provides an experimental platform for quantifying the phenotypic response to gene expression variation.

Effect of Different Combinations of Panchagavya on Plant Yield

Use of organic fertilizer is being promoted as the sustainable method of agriculture for maximizing yield. In this study the six different combinations of Panchagavya are prepared and laboratory growth study is made using seed. Vigour index is used for quantifying growth rate of seeds. Result indicates that 500ml of tender coconut water added to the control combination gives maximum yield. The efficacy of the optimal Panchagavya combination from the lab study is applied to the field directly yielding much higher growth than the other methods used by the farmers.

A Proposed Methodology to Analyze Plant Growth and Movement from Phenomics Data

Image analysis of developmental processes in plants reveals both growth and organ movement. This study proposes a methodology to study growth and movement. It includes the standard acquisition of internal and external reference points and coordinates, coordinates transformation, curve fitting and the corresponding statistical analysis. Several species with different growth habits were used including Antirrhinum majus, A. linkianum, Petunia x hybrida and Fragaria x ananassa. Complex growth patterns, including gated growth, could be identified using a generalized additive model. Movement, and in some cases, growth, could not be adjusted to curves due to drastic changes in position. The area under the curve was useful in order to identify the initial stage of growth of an organ, and its growth rate. Organs displayed either continuous movements during the day with gated day/night periods of maxima, or sharp changes in position coinciding with day/night shifts. The movement was dependent on light in petunia and independent in F. ananassa. Petunia showed organ movement in both growing and fully-grown organs, while A. majus and F. ananassa showed both leaf and flower movement patterns linked to growth. The results indicate that different mathematical fits may help quantify growth rate, growth duration and gating. While organ movement may complicate image and data analysis, it may be a surrogate method to determine organ growth potential.

In situ growth rate estimates of Southern Ocean krill, Thysanoessa macrura

AbstractGrowth, which is intrinsically linked to environmental conditions including temperature and food availability are highly variable both temporally and spatially. Estimates of growth rates of the Southern Ocean euphausiid Thysanoessa macrura are currently restricted to limited studies which rely upon repeated sampling and length-frequency analysis to quantify growth rates. The instantaneous growth method (IGR) was used to measure the growth rate of T. macrura successfully in the southern Kerulen Plateau region during summer, providing the first IGR parameters for the Southern Ocean euphausiid species. Results of the four-day IGR incubation indicate a period of low somatic growth for adult T. macrura. Males had a longer intermoult period (IMP) (62 days) than females (42 days), but the sexes exhibited similar daily growth rates of 0.011 mm day−1 and 0.012 mm day−1 respectively. Juveniles exhibited the fastest growth, with an IMP of 13 days and daily growth rate of 0.055 mm day−1 indicating a prolonged growth season, similar to the Antarctic krill E. superba. Consequently, we highlight the usability of the IGR method and strongly encourage its use in developing a comprehensive understanding of spatial and seasonal growth patterns of T. macrura.

High-throughput quantification of microbial birth and death dynamics using fluorescence microscopy.

Microbes live in dynamic environments where nutrient concentrations fluctuate. Quantifying fitness in terms of birth rate and death rate in a wide range of environments is critical for understanding microbial evolution and ecology. Here, using high-throughput time-lapse microscopy, we have quantified how Saccharomyces cerevisiae mutants incapable of synthesizing an essential metabolite (auxotrophs) grow or die in various concentrations of the required metabolite. We establish that cells normally expressing fluorescent proteins lose fluorescence upon death and that the total fluorescence in an imaging frame is proportional to the number of live cells even when cells form multiple layers. We validate our microscopy approach of measuring birth and death rates using flow cytometry, cell counting, and chemostat culturing. For lysine-requiring cells, very low concentrations of lysine are not detectably consumed and do not support cell birth, but delay the onset of death phase and reduce the death rate compared to no lysine. In contrast, in low hypoxanthine, hypoxanthine-requiring cells can produce new cells, yet also die faster than in the absence of hypoxanthine. For both strains, birth rates under various metabolite concentrations are better described by the sigmoidal-shaped Moser model than the well-known Monod model, while death rates can vary with metabolite concentration and time. Our work reveals how time-lapse microscopy can be used to discover non-intuitive microbial birth and death dynamics and to quantify growth rates in many environments.

Surveillance of abdominal aortic aneurysm using accelerated 3D non-contrast black-blood cardiovascular magnetic resonance with compressed sensing (CS-DANTE-SPACE)

Background3D non-contrast high-resolution black-blood cardiovascular magnetic resonance (CMR) (DANTE-SPACE) has been used for surveillance of abdominal aortic aneurysm (AAA) and validated against computed tomography (CT) angiography. However, it requires a long scan time of more than 7 min. We sought to develop an accelerated sequence applying compressed sensing (CS-DANTE-SPACE) and validate it in AAA patients undergoing surveillance.MethodsThirty-eight AAA patients (all males, 73 ± 6 years) under clinical surveillance were recruited for this study. All patients were scanned with DANTE-SPACE (scan time 7:10 min) and CS-DANTE-SPACE (scan time 4:12 min, a reduction of 41.4%). Nine 9 patients were scanned more than 2 times. In total, 50 pairs of images were available for comparison. Two radiologists independently evaluated the image quality on a 1–4 scale, and measured the maximal diameter of AAA, the intra-luminal thrombus (ILT) and lumen area, ILT-to-muscle signal intensity ratio, and the ILT-to-lumen contrast ratio. The sharpness of the aneurysm inner/outer boundaries was quantified.ResultsCS-DANTE-SPACE achieved comparable image quality compared with DANTE-SPACE (3.15 ± 0.67 vs. 3.03 ± 0.64, p = 0.06). There was excellent agreement between results from the two sequences for diameter/area and ILT ratio measurements (ICCs> 0.85), and for quantifying growth rate (3.3 ± 3.1 vs. 3.3 ± 3.4 mm/year, ICC = 0.95.) CS-DANTE-SPACE showed a higher ILT-to-lumen contrast ratio (p = 0.01) and higher sharpness than DANTE-SPACE (p = 0.002). Both sequences had excellent inter-reader reproducibility for quantitative measurements (ICC > 0.88).ConclusionCS-DANTE-SPACE can reduce scan time while maintaining image quality for AAA imaging. It is a promising tool for the surveillance of patients with AAA disease in the clinical setting.

Antibiotic export by efflux pumps affects growth of neighboring bacteria

Cell-cell interactions play an important role in bacterial antibiotic resistance. Here, we asked whether neighbor proximity is sufficient to generate single-cell variation in antibiotic resistance due to local differences in antibiotic concentrations. To test this, we focused on multidrug efflux pumps because recent studies have revealed that expression of pumps is heterogeneous across populations. Efflux pumps can export antibiotics, leading to elevated resistance relative to cells with low or no pump expression. In this study, we co-cultured cells with and without AcrAB-TolC pump expression and used single-cell time-lapse microscopy to quantify growth rate as a function of a cell’s neighbors. In inhibitory concentrations of chloramphenicol, we found that cells lacking functional efflux pumps (ΔacrB) grow more slowly when they are surrounded by cells with AcrAB-TolC pumps than when surrounded by ΔacrB cells. To help explain our experimental results, we developed an agent-based mathematical model, which demonstrates the impact of neighbors based on efflux efficiency. Our findings hold true for co-cultures of Escherichia coli with and without pump expression and also in co-cultures of E. coli and Salmonella typhumirium. These results show how drug export and local microenvironments play a key role in defining single-cell level antibiotic resistance.

Heat Induced Limb Length Asymmetry Has Functional Impact on Weight Bearing in Mouse Hindlimbs

Limb length inequality results from many types of musculoskeletal disorders ranging from injury and illness to bone disease. Asymmetric weight bearing from a limb length discrepancy of less than 2% can have painful outcomes such as back problems and early onset osteoarthritis. Existing treatments include invasive surgeries and/or drug regimens that are often only partially effective. We previously developed a noninvasive, once daily unilateral heating model using targeted heat to increase limb length on one side of the body of growing mice. After two weeks, we demonstrated that tibial elongation rate increased &gt;12% on the heat‐treated side with accompanying unilateral increases in femoral (1.3%) and tibial (1.5%) lengths. In this study, we applied heat for one week to determine whether these small differences in limb length are functionally significant, assessed by changes in hindlimb weight bearing. We tested the hypothesis that heat induced limb length asymmetry has a functional impact on weight bearing in mouse hindlimbs. To test this, we measured tibial length and weight distribution before and after limb heating. If small changes in limb length cause imbalanced weight distribution as hypothesized, we expect to find a positive relationship between weight bearing asymmetry and limb length inequality after treatment.MethodsFemale 3‐week old C57BL/6 mice (N=12 total) were treated with targeted intermittent heat for 7 days (40C for 40 min/day). High‐resolution X‐ray images (N=6) and hindlimb weight bearing data (N=8) were acquired at the start and end of the experiments. Mice were given oxytetracycline (OTC, 7.5 mg/kg IP) to quantify growth rate, which was measured in unfixed proximal tibial slab sections on a fluorescence stereoscope. Tibial length was measured from live animal X‐rays and femoral length was measured from digitized bone images at the 4‐week endpoint. Statistical analyses were performed in SPSS using paired t‐tests and correlation. Significance was accepted at α = 0.05 (one‐tailed).ResultsThere were no significant left‐right differences in starting tibial length or hindlimb weight bearing at 3‐weeks. After one week intermittent heat exposure, endpoint tibial (t = 7.7, p &lt; 0.001) and femoral lengths (t = 11.5, p &lt; 0.001) were ~1% and 1.3% greater, respectively, on the heat‐treated sides (40C) compared to the non‐treated contralateral sides (30C). Tibial elongation rate was over 6% greater on the heat‐treated side (t = 5.19, p &lt; 0.001). Hindlimb weight bearing was over 20% greater (t = 11.9, p &lt; 0.001) and significantly correlated with the increase in tibial elongation rate on the heat‐treated side (Pearson's R = 0.91, p &lt; 0.01).DiscussionThese results support the hypothesis that even a small limb length discrepancy (less than 1.5%) can cause imbalanced weight distribution (over 20%) in healthy mice. This research has practical relevance for treating a broad spectrum of linear growth disorders in children. The increase in bone elongation rate generated by targeted heat could help equalize limb length and weight bearing asymmetry caused by disease or trauma. Results could lead to new approaches with better outcomes by using targeted heat therapy to reduce costs and side effects of surgeries and high‐dose pharmaceuticals.Support or Funding InformationSupported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (1R15AR067451‐01).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Combination Therapies with Antimicrobial Peptide LL-37 and Conventional Antibiotics

The emergence of antibiotic resistance is one of the largest problems in current public health. A potential solution is combination therapy, where two or more drugs are combined to fight resistant bacteria. In this work, we evaluate harnessing the power of antimicrobial peptides (AMPs), which are part of the innate immunity of virtually all eukaryotic life. The evolutionary stability of AMPs hints that it is difficult for bacteria to develop resistance against AMPs’ mechanism of action, which is based on membrane perturbation. We conducted a battery of combination therapy tests to determine the outcome of combining AMPs with more than 20 conventional antibiotics representing a range of drug classes. To this end, we employed a serial dilution method to test the effect of combining varying dosages of AMPs and antibiotics on growth of Escherichia coli cultures. A robust statistical analysis of the experimental data allows us to quantify growth rates and any extended delay in initial growth to discern if and to what extent any interactions occur. We discovered that AMPs’ and antibiotics’ action influence each other. Certain drugs, like chloramphenicol, experienced heightened antibacterial activity while other drugs, like streptomycin, were suppressed. Ultimately, our results give insight into how antibiotic effectivity in a clinical setting can be impacted by these naturally occurring biomolecules.

A \u201cDo-It-Yourself\u201d phenotyping system: measuring growth and morphology throughout the diel cycle in rosette shaped plants

BackgroundImprovements in high-throughput phenotyping technologies are rapidly expanding the scope and capacity of plant biology studies to measure growth traits. Nevertheless, the costs of commercial phenotyping equipment and infrastructure remain prohibitively expensive for wide-scale uptake, while academic solutions can require significant local expertise. Here we present a low-cost methodology for plant biologists to build their own phenotyping system for quantifying growth rates and phenotypic characteristics of Arabidopsis thaliana rosettes throughout the diel cycle.ResultsWe constructed an image capture system consisting of a near infra-red (NIR, 940 nm) LED panel with a mounted Raspberry Pi NoIR camera and developed a MatLab-based software module (iDIEL Plant) to characterise rosette expansion. Our software was able to accurately segment and characterise multiple rosettes within an image, regardless of plant arrangement or genotype, and batch process image sets. To further validate our system, wild-type Arabidopsis plants (Col-0) and two mutant lines with reduced Rubisco contents, pale leaves and slow growth phenotypes (1a3b and 1a2b) were grown on a single plant tray. Plants were imaged from 9 to 24 days after germination every 20 min throughout the 24 h light–dark growth cycle (i.e. the diel cycle). The resulting dataset provided a dynamic and uninterrupted characterisation of differences in rosette growth and expansion rates over time for the three lines tested.ConclusionOur methodology offers a straightforward solution for setting up automated, scalable and low-cost phenotyping facilities in a wide range of lab environments that could greatly increase the processing power and scalability of Arabidopsis soil growth experiments.

Emergence and Progression of Abnormal Grain Growth in Minimally Strained Nickel-200

Grain boundary engineering (GBE) is a thermomechanical processing technique used to control the distribution, arrangement, and identity of grain boundary networks, thereby improving their mechanical properties. In both GBE and non-GBE metals, the phenomena of abnormal grain growth (AGG) and its contributing factors is still a subject of much interest and research. In a previous study, GBE was performed on minimally strained (ε &lt; 10%), commercially pure Nickel-200 via cyclic annealing, wherein unique onset temperature and induced strain pairings were identified for the emergence of AGG. In this study, crystallographic segmentation of grain orientations from said experiments are leveraged in tandem with image processing to quantify growth rates for abnormal grains within the minimally strained regime. Advances in growth rates are shown to vary directly with initial strain content but inversely with initiating AGG onset temperature. A numeric estimator for advancement rates associated with AGG is also derived and presented.

Characterizing mandibular growth using three-dimensional imaging techniques and anatomic landmarks

ObjectiveTo provide quantitative data on the multi-planar growth of the mandible, this study derived accurate linear and angular mandible measurements using landmarks on three dimensional (3D) mandible models. This novel method was used to quantify 3D mandibular growth and characterize the emergence of sexual dimorphism. DesignCross-sectional and longitudinal imaging data were obtained from a retrospective computed tomography (CT) database for 51 typically developing individuals between the ages of one and nineteen years. The software Analyze was used to generate 104 3DCT mandible models. Eleven landmarks placed on the models defined six linear measurements (lateral condyle, gonion, and endomolare width, ramus and mental depth, and mandible length) and three angular measurements (gonion, gnathion, and lingual). A fourth degree polynomial fit quantified growth trends, its derivative quantified growth rates, and a composite growth model determined growth types (neural/cranial and somatic/skeletal). Sex differences were assessed in four age cohorts, each spanning five years, to determine the ontogenetic pattern producing sexual dimorphism of the adult mandible. ResultsMandibular growth trends and growth rates were non-uniform. In general, structures in the horizontal plane displayed predominantly neural/cranial growth types, whereas structures in the vertical plane had somatic/skeletal growth types. Significant prepubertal sex differences in the inferior aspect of the mandible dissipated when growth in males began to outpace that of females at eight to ten years of age, but sexual dimorphism re-emerged during and after puberty. ConclusionsThis 3D analysis of mandibular growth provides preliminary normative developmental data for clinical assessment and craniofacial growth studies.

Growth strategies of tadpoles along the pond permanency gradient

The preference for particular features of water bodies for reproduction is one of the most important aspects of anuran ecology, affecting key aspects of both tadpole and adult life. The use by species of different habitats along the pond permanency gradient has been already studied, noting conflicting selective pressures from predation and desiccation risk. Here, we aim to discover physiological patterns related with this gradient. As a study system, we used the full anuran community of the NE Iberian Peninsula. We quantified growth rate, consumption rate, food assimilation and the proportion of energy allocated to growth, as well as gut length, for all species. Food consumption rate and growth allocation were the variables that defined tadpole growth, while food assimilation abilities and gut length seem to have a secondary or cryptic role in growth. More interestingly however, our data suggests a labile continuum of consumption-based versus allocation/assimilation-based growth strategies differentiating species. Differences among species follow predictions of adaptation to the pond permanency gradient selective pressures. Species from ephemeral ponds are more prone to use consumption-related growth tactics while species inhabiting ponds with longer hydroperiods are more efficient retaining and allocating energy into growth, although results seem partly shaped by strong interspecific competition. Physiological differences in growth and the usage of the assimilated energy could be an additional factor to understand how tadpoles adapt to the features of ponds they inhabit, as well as how they compete and coexist.

Wavelength-normalized spectroscopic analysis of Staphylococcus aureus and Pseudomonas aeruginosa growth rates.

Optical density (OD) measurements are the standard approach used in microbiology for characterizing bacteria concentrations in culture media. OD is based on measuring the optical absorbance of a sample at a single wavelength, and any error will propagate through all calculations, leading to reproducibility issues. Here, we use the conventional OD technique to measure the growth rates of two different species of bacteria, Pseudomonas aeruginosa and Staphylococcus aureus. The same samples are also analyzed over the entire UV-Vis wavelength spectrum, allowing a distinctly different strategy for data analysis to be performed. Specifically, instead of only analyzing a single wavelength, a multi-wavelength normalization process is implemented. When the OD method is used, the detected signal does not follow the log growth curve. In contrast, the multi-wavelength normalization process minimizes the impact of bacteria byproducts and environmental noise on the signal, thereby accurately quantifying growth rates with high fidelity at low concentrations.