scholarly journals Environmental conditions, not sugar export efficiency, limit the length of conifer leaves

2018 ◽  
Vol 39 (2) ◽  
pp. 312-319
Author(s):  
Xiaoyu Han ◽  
Robert Turgeon ◽  
Alexander Schulz ◽  
Johannes Liesche
Keyword(s):  
Mathematical Model ◽  
Light Availability ◽  
Sugar Transport ◽  
Leaf Size ◽  
Phloem Transport ◽  
Limiting Factor ◽  
Needle Length ◽  
Physiological Factors ◽  
Needle Size ◽  
General Variation

Abstract Most conifer species have needle-shaped leaves that are only a few centimeters long. In general, variation in leaf size has been associated with environmental factors, such as cold or drought stress. However, it has recently been proposed that sugar export efficiency is the limiting factor for conifer needle length, based on the results obtained using a mathematical model of phloem transport. Here, phloem transport rates in long conifer needles were experimentally determined to test if the mathematical model accurately represents phloem transport. The validity of the model’s assumptions was tested by anatomical analyses and sugar quantification. Furthermore, various environmental and physiological factors were tested for their correlation with needle length. The results indicate that needle length is not limited by sugar transport efficiency, but, instead, by winter temperatures and light availability. The identification of factors that influence needle size is instrumental for using this trait as a variable in breeding programs.

scholarly journals Simulation of the gastric digestion of proteins of meat bolus using a reaction–diffusion model

2018 ◽  
Vol 9 (12) ◽  
pp. 6455-6469 ◽  
Author(s):  
Jason Sicard ◽  
Pierre-Sylvain Mirade ◽  
Stéphane Portanguen ◽  
Sylvie Clerjon ◽  
Alain Kondjoyan
Keyword(s):  
Mathematical Model ◽  
Diffusion Model ◽  
Reaction Diffusion ◽  
Gastric Digestion ◽  
Physiological Factors ◽  
Reaction Diffusion Model ◽  
Meat Proteins

A mathematical model predicts the gastric digestion of meat proteins and quantifies the impacts of physiological factors on digestibility.

scholarly journals A subunit gene of sucrose non-fermenting 1 related kinase, PpSnRK1γ, confers flat fruit abortion in peach by regulating sugar and starch metabolism

2020 ◽  
Author(s):  
Jian Guo ◽  
Ke Cao ◽  
Jia-long Yao ◽  
Cecilia Deng ◽  
Yong Li ◽  
...  
Keyword(s):  
Candidate Gene ◽  
Fruit Production ◽  
Fruit Shape ◽  
Limiting Factor ◽  
Peach Fruit ◽  
Physiological Factors ◽  
Peach Breeding ◽  
A Subunit ◽  
Fruit Abortion ◽  
Transient Overexpression

Abstract Background: Fruit abortion is a major limiting factor for fruit production. In flat peach, fruit abortion is present in the whole tree of some accessions during early fruit development. However, the physiological factors and genetic mechanism underlying flat fruit abortion remain largely elusive. Results: In this study, we have revealed that the fertilization process was accomplished and the reduction of sucrose and starch contents might result in flat fruit abortion. By combining association and gene expression analysis, a key candidate gene, PpSnRK1γ, was identified. A 1.67-Mb inversion co-segregated with flat fruit shape altered the promoter activity of PpSnRK1γ, resulting in much lower expression in aborting flat peach. Ectopic transformation in tomato and transient overexpression in peach fruit have shown that PpSnRK1γ could increase sugar and starch contents. Comparative transcriptome analysis further confirmed that PpSnRK1γ participated in carbohydrate metabolism. Subcellular localization found that PpSnRK1γ was located in nucleus. Conclusions: This study clarified the reason for flat fruit abortion and identified a critical candidate gene, PpSnRK1γ, responsible for fruit abortion in peach. The results would provide great help in peach breeding and facilitate gene identification for fruit abortion in other plant species.

scholarly journals Radial-axial transport coordination enhances sugar translocation in the phloem vasculature of plants

2021 ◽  
Author(s):  
Mazen Nakad ◽  
Jean-Christophe Domec ◽  
Sanna A Sevanto ◽  
Gabriel G. Katul
Keyword(s):  
Mass Transport ◽  
Water Exchange ◽  
Carbon Allocation ◽  
Sugar Transport ◽  
Phloem Transport ◽  
Two Dimensions ◽  
Frictional Stress ◽  
Front Speed ◽  
Wide Range ◽  
And Function

Understanding the controls of mass transport of photosynthates in the phloem of plants is necessary for describing plant carbon allocation, productivity, and responses to water and thermal stress. While several hypotheses about optimization of phloem structure and function, and limitations of phloem transport under drought have been tested both with models and anatomical data, the true impact of radial water exchange of phloem conduits with their surroundings on mass transport of photosynthates has not been addressed. Here the physics of the Munch mechanism of sugar transport is re-evaluated to include local variations in viscosity resulting from the radial water exchange in two dimensions (axial and radial). Model results show that radial water exchange pushes sucrose away from conduit walls thereby reducing wall frictional stress due to a decrease in sap viscosity and increasing sugar concentration in the central region of the conduit. This leads to increased sugar front speed and axial mass transport for a wide range of phloem conduit lengths and allows sugar transport to operate more efficiently than predicted by previous models. A faster front speed leads to higher phloem resiliency under drought because more sugar can be transported with a smaller pressure gradient.

Effects of shading on seagrass morphology and thermal optimal of productivity

2020 ◽  
Vol 71 (8) ◽  
pp. 913 ◽  
Author(s):  
Eunice Kong ◽  
Yan Xiang Ow ◽  
Samantha Lai ◽  
Siti Maryam Yaakub ◽  
Peter Todd
Keyword(s):  
Synergistic Effects ◽  
Light Availability ◽  
Temperature Response ◽  
Leaf Size ◽  
Net Photosynthesis ◽  
Shoot Density ◽  
Net Productivity ◽  
Halophila Ovalis ◽  
Light Levels ◽  
Reduced Light

Light and temperature are important factors affecting seagrass primary productivity. Acclimatisation to reduced light availability may affect the optimal temperature at which seagrasses photosynthesise, potentially causing synergistic effects between increasing water temperatures and decreasing light levels on coastal productivity. This study investigated the effects of reduced light availability on the morphology (leaf size, shoot density) and thermal optimal of net productivity in Halophila ovalis (R.Br.) Hook. A 12-week in situ shading experiment was conducted at Chek Jawa Wetlands, Singapore, testing high (68% shading), low (49%) and control (0%) shadings. Every 4 weeks, photosynthetic and respiration rates of H. ovalis leaves and the root–rhizome complex were measured in closed incubation chambers at temperatures from 22 to 42°C (at 4°C intervals). A fitted temperature-response model of net photosynthesis was used to estimate the thermal optimal for each shading treatment. High shading reduced shoot density (mean±s.e.) 87.06±7.86% and leaf surface area 31.72±24.74%. Net productivity (6mg O2 g–1 DW h–1) and its thermal optimal (28–30°C) were not significantly different among shading treatments throughout the experiment. Light levels appeared to have minimal influence on the thermal dependency of H. ovalis net productivity.

Poly(β-hydroxyalkanoate) accumulation in bacterioplankton from Lake Cisó (Spain)

1995 ◽  
Vol 41 (13) ◽  
pp. 80-83 ◽  
Author(s):  
J. Mas-Castellà ◽  
R. Guerrero
Keyword(s):  
Light Availability ◽  
Growth Conditions ◽  
Phototrophic Bacteria ◽  
Light Limitation ◽  
Limiting Factor ◽  
Specific Content ◽  
Unbalanced Growth ◽  
Bacterial Counts ◽  
Large Populations ◽  
Different Depths

The specific poly(β-hydroxyalkanoate) (PHA) content of the bacterioplankton from Lake Cisó (Spain) was measured at different depths. Phototrophic bacteria reach large populations in this lake and the PHA concentration changed seasonally according to their biomass. During summer stratification of the lake, phototrophic bacteria formed a metalimnetic peak. Bacterial counts were maximal at a depth of 1.5–2.0 m, whereas the PHA specific content reached a maximal value at 3.0–3.5 m. Since the limiting factor in this ecosystem is light availability, we assume that cells beneath the dense metalimnetic peak have unbalanced growth conditions and thus accumulate large amounts of PHA.Key words: bacterioplankton, PHA accumulation, Lake Cisó, light limitation.

Unusual occurrence of a Didymosphenia bloom in a lentic habitat: Observation of Didymosphenia laticollis blooming on the eastern shore of Lake Hövsgöl (Mongolia)

Phytotaxa ◽  
2016 ◽  
Vol 263 (2) ◽  
pp. 139 ◽  
Author(s):  
MARCO CANTONATI ◽  
DITMAR METZELTIN ◽  
NERGUI SONINKHISHIG ◽  
HORST LANGE-BERTALOT
Keyword(s):  
Light Availability ◽  
Limiting Factor ◽  
Running Waters ◽  
Eastern Shore ◽  
Bloom Formation ◽  
Lake Hovsgol ◽  
Western Shore ◽  
High Alkalinity ◽  
Unusual Occurrence ◽  
Formation Conditions

The stalked diatom Didymosphenia is being thoroughly studied because it can cause serious nuisance blooms. The species most commonly involved is D. geminata. Although Didymosphenia species occur in running waters and lakes, published reports generally refer to lotic habitats. Given the applied interest in Didymosphenia, as well as its suitability for fundamental ecological studies, here we report an observation of a Didymosphenia bloom occurring on the southern part of the eastern shore of the large oligotrophic Lake Hövsgöl (Mongolia). LM and SEM observations revealed that the bloom was formed by Didymosphenia laticollis. The bloom extended for a long stretch of the eastern shore whilst on the opposing lake margin no bloom was visible, where a different Didymosphenia species was collected (D. mongolica). We interpreted the Lake Hövsgöl D. laticollis bloom in light of the most updated knowledge on Didymosphenia blooms ecophysiology. Lake Hövsgöl meets all main environmental requirements for Didymosphenia bloom formation: conditions are oligotrophic and phosphorus is the limiting factor, waters are very transparent and benthic light availability is consequently high, alkalinity is relatively high, and stable rocky substrata in a hydrologically-turbulent environment are widespread. The light-brown color of the bloom is in good agreement with experimental results suggesting that low-SRP conditions promote bloom formation in the presence of high light and alkalinity, because energy is converted to stalk material (the primary site of alkaline phosphatase production in Didymosphenia) rather than in cells. We speculate that the occurrence of the bloom on the eastern shore and its absence on the western shore might depend upon morphology, land use, and climate change causing alkalinity and organic phosphate inputs on the eastern side.

Quantitative Circulatory Physiology: an integrative mathematical model of human physiology for medical education

2007 ◽  
Vol 31 (2) ◽  
pp. 202-210 ◽  
Author(s):  
Sean R. Abram ◽  
Benjamin L. Hodnett ◽  
Richard L. Summers ◽  
Thomas G. Coleman ◽  
Robert L. Hester
Keyword(s):  
Mathematical Model ◽  
Human Physiology ◽  
Physiological Function ◽  
Biological Interactions ◽  
Physiological Factors ◽  
Integrative Physiology ◽  
Physiological Variables ◽  
Circulatory Physiology ◽  
Practice Of Medicine ◽  
Clinical Problems

We have developed Quantitative Circulatory Physiology (QCP), a mathematical model of integrative human physiology containing over 4,000 variables of biological interactions. This model provides a teaching environment that mimics clinical problems encountered in the practice of medicine. The model structure is based on documented physiological responses within peer-reviewed literature and serves as a dynamic compendium of physiological knowledge. The model is solved using a desktop, Windows-based program, allowing students to calculate time-dependent solutions and interactively alter over 750 parameters that modify physiological function. The model can be used to understand proposed mechanisms of physiological function and the interactions among physiological variables that may not be otherwise intuitively evident. In addition to open-ended or unstructured simulations, we have developed 30 physiological simulations, including heart failure, anemia, diabetes, and hemorrhage. Additional stimulations include 29 patients in which students are challenged to diagnose the pathophysiology based on their understanding of integrative physiology. In summary, QCP allows students to examine, integrate, and understand a host of physiological factors without causing harm to patients. This model is available as a free download for Windows computers at http://physiology.umc.edu/themodelingworkshop .

Needle Thoracostomy: Does Changing Needle Length and Location Change Patient Outcome?

2018 ◽  
Vol 33 (3) ◽  
pp. 237-244 ◽  
Author(s):  
Lori A. Weichenthal ◽  
Scott Owen ◽  
Geoffory Stroh ◽  
John Ramos
Keyword(s):  
Patient Outcome ◽  
Injury Severity ◽  
Trauma Patients ◽  
Needle Length ◽  
Publication Type ◽  
Clinical Change ◽  
Needle Size ◽  
Severity Scores ◽  
Before And After ◽  
Location Change

AbstractBackgroundNeedle thoracostomy (NT) is a common prehospital intervention for patients in extremis or cardiac arrest due to trauma. The purpose of this study is to compare outcomes, efficacy, and complications after a change in policy related to NT in a four-county Emergency Medical Services (EMS) system with a catchment area of greater than 1.6 million people.MethodsThis is a before and after observational study of all patients who had NT performed in the Central California (USA) EMS system. The before, anterior midclavicular line (MCL) group consisted of all patients who underwent NT from May 7, 2007 through February 28, 2013. The after, midaxillary line (MAL) axillary group consisted of all patients who underwent NT from March 1, 2013 through January 30, 2016, after policy revisions changed the timing, needle size, and placement location for NT. All prehospital and hospital records where NT was performed were queried for demographics, mechanism of injury, initial status and post-NT clinical change, reported complications, and final outcome. The trauma registry was accessed to obtain Injury Severity Scores (ISS). Information was manually abstracted by study investigators and examined utilizing univariate and multivariate analyses.ResultsThree-hundred and five trauma patients treated with NT were included in this study, of which, 169 patients (the MCL group) were treated with a 14-guage intravenous (IV) catheter at least 5.0-cm long at the second intercostal space (ICS), MCL after being placed in the ambulance; and 136 patients (the MAL group) were treated with a 10-guage IV catheter at least 9.5-cm long at the fifth ICS, MAL on scene. The mean ISS was lower in the MAL cohort (64.5 versus 69.2; P=.007). The mortality rate was 79% in both groups. The multivariate model with regard to survival supported that a lower ISS (P<.001) and reported clinical change after NT (P=.003) were significant indicators of survival. No complications from NT were reported.ConclusionsChanging the timing, length of needle, and location of placement did not change mortality in patients requiring NT. Needle thoracostomy was used more frequently after the change in policy, and the MAL cohort was less injured. No increase in reported complications was noted.WeichenthalLA, OwenS, StrohG, RamosJ. Needle thoracostomy: does changing needle length and location change patient outcome?Prehosp Disaster Med. 2018;33(3):237–244.

scholarly journals Temperature-Dependent Kinetic Model for Nitrogen-Limited Wine Fermentations

2007 ◽  
Vol 73 (18) ◽  
pp. 5875-5884 ◽  
Author(s):  
Matthew C. Coleman ◽  
Russell Fish ◽  
David E. Block
Keyword(s):  
Mathematical Model ◽  
Cell Mass ◽  
Sugar Transport ◽  
Wine Fermentation ◽  
Model Parameters ◽  
Yield Coefficient ◽  
Temperature Dependent ◽  
Fermentation Kinetics ◽  
Different Temperatures ◽  
Wine Fermentations

ABSTRACT A physical and mathematical model for wine fermentation kinetics was adapted to include the influence of temperature, perhaps the most critical factor influencing fermentation kinetics. The model was based on flask-scale white wine fermentations at different temperatures (11 to 35°C) and different initial concentrations of sugar (265 to 300 g/liter) and nitrogen (70 to 350 mg N/liter). The results show that fermentation temperature and inadequate levels of nitrogen will cause stuck or sluggish fermentations. Model parameters representing cell growth rate, sugar utilization rate, and the inactivation rate of cells in the presence of ethanol are highly temperature dependent. All other variables (yield coefficient of cell mass to utilized nitrogen, yield coefficient of ethanol to utilized sugar, Monod constant for nitrogen-limited growth, and Michaelis-Menten-type constant for sugar transport) were determined to vary insignificantly with temperature. The resulting mathematical model accurately predicts the observed wine fermentation kinetics with respect to different temperatures and different initial conditions, including data from fermentations not used for model development. This is the first wine fermentation model that accurately predicts a transition from sluggish to normal to stuck fermentations as temperature increases from 11 to 35°C. Furthermore, this comprehensive model provides insight into combined effects of time, temperature, and ethanol concentration on yeast (Saccharomyces cerevisiae) activity and physiology.

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