A quantitative model of leaflet initiation illustrated by Murraya paniculata (Rutaceae)

1993 ◽  
Vol 71 (3) ◽  
pp. 457-465 ◽  
Author(s):  
Bernard Jeune ◽  
Christian R. Lacroix
Keyword(s):  
Mathematical Model ◽  
Growth Rates ◽  
Leaf Development ◽  
Growth Parameters ◽  
Quantitative Model ◽  
Leaf Primordia ◽  
Basic Assumptions ◽  
Fixed Distance ◽  
Murraya Paniculata ◽  
Development Support

A modified mathematical model based on the concept of generative centers is proposed to describe organogenesis in young leaf primordia of Murraya paniculata. Measurements of specific parameters on leaf primordia at different stages of development support the basic assumptions of the model. These assumptions are exponential elongation and widening of primordia in the organogenetic phase and rhythmic production of lateral elements at a fixed distance from the apex of the developing primordium. In general, the model provides good estimates for growth parameters such as elemental growth rates. It also provides a relatively accurate description of the shape of the primordium during the organogenesis of lateral elements or leaflet primordia. Key words: leaf development, mathematical model, organogenesis, compound leaf, Murraya paniculata.

Expression of shoot features in early leaf development of Murraya paniculata (Rutaceae)

1994 ◽  
Vol 72 (5) ◽  
pp. 678-687 ◽  
Author(s):  
Christian R. Lacroix ◽  
Rolf Sattler
Keyword(s):  
Early Development ◽  
Leaf Development ◽  
Sagittal Plane ◽  
Frontal Plane ◽  
Flowering Plants ◽  
Leaf Primordia ◽  
Differential Growth ◽  
Pinnate Leaf ◽  
Murraya Paniculata ◽  
Phylogenetic Perspective

The early development of the pinnately compound leaves in Murraya paniculata was studied using both epi-illumination and scanning electron microscopy as well as semithin plastic sectioning of the same specimens that were illustrated by means of epi-illumination. It is shown that morphological conclusions may be influenced by technical approaches such as the plane of sectioning. If the developing leaves are sectioned in the (median) sagittal plane, they appear to be rather different from stems and shoots. If, however, they are sectioned in the frontal plane, perpendicular to the sagittal plane, they appear more shoot-like in early development. Their apex could be described in terms of a tunica-corpus organization and the leaflet primordia are initiated like leaf primordia on a shoot tip with distichous phyllotaxy sensu lato. Subsequently, due to differential growth, reorientation of the leaflets occurs in one plane. Thus, the planar structure of the pinnate leaf is ontogenetically secondary. From a phylogenetic perspective, at least two conclusions are possible for plants with pinnate leaves such as those of Murraya: (i) if the ancestor of a pinnate taxon had simple leaves, the pinnate condition arose through homeosis, i.e., the expression of shoot features in leaf sites; (ii) if the ancestor of a pinnate taxon did not have simple leaves, the shoot-like early development of the pinnate leaves may indicate a common evolutionary basis of shoots and pinnate leaves in primitive branching systems. Since it is generally thought that the most primitive angiosperms have simple leaves, the homeotic hypothesis appears to be the preferred hypothesis for the origin of compound leaves in flowering plants. Key words: leaf development, comparative morphogenesis, shoot–leaf relationships, partial shoot theory of the leaf, homeosis.

Growth and movement of the South African abalone Haliotis midae: A reassessment

1995 ◽  
Vol 46 (3) ◽  
pp. 583 ◽  
Author(s):  
RJQ Tarr
Keyword(s):  
South African ◽  
Growth Rates ◽  
Growth Parameters ◽  
Eastern Coast ◽  
Island Population ◽  
Western Coast ◽  
Eastern Cape ◽  
The South ◽  
Significant Difference ◽  
Haliotis Midae

Growth rates of a number of Haliotis midae populations around the South African coast were studied by means of tagging. These populations ranged from the cool waters of the western coast to the more temperate environment of the eastern Cape. Standard von Bertalanffy growth curves were fitted and growth parameters derived. These ranged from 0.19 to 0.25 for K, the average rate at which L∞ is approached, and from 156 to 173 for L∞, the average theoretical maximum length. These indicate far higher growth rates than were previously published for this commercially fished species, and the reasons for this difference are discussed. The expectation that growth rates would be fastest in the warmer eastern Cape waters was not realized, there being no significant difference in growth between the Bird Island population on the eastern coast and the Robben Island population on the western coast. These new growth parameters indicate that H. midae in the commercial fishery grounds is attaining sexual maturity some four years earlier, and the minimum legal size some five years earlier, than previously considered. This has considerable significance for modelling studies presently underway. Movement of a small population of adult H. midae was studied over a three-year period, after which 47% of the original abalone were still present on the study site. Of these, 81.5% still occupied exactly the same position on the rocks. This indicates that H. midae that have located an optimum habitat, and that are not disturbed, tend not to move.

Modeling the Growth of Salmonella in Cut Red Round Tomatoes as a Function of Temperature

2010 ◽  
Vol 73 (8) ◽  
pp. 1502-1505 ◽  
Author(s):  
WENJING PAN ◽  
DONALD W. SCHAFFNER
Keyword(s):  
Mathematical Model ◽  
Growth Rates ◽  
Low Temperatures ◽  
Safety Concern ◽  
Time Intervals ◽  
Salmonella Serotypes ◽  
Increasing Temperature ◽  
Incubation Temperatures ◽  
Raw Poultry ◽  
The Relationship

Tomato-associated Salmonella outbreaks have recently become a significant food safety concern. Temperature abuse of cut tomatoes may have played a role in some of these outbreaks. The purpose of this study was to develop a mathematical model to describe the growth of Salmonella on cut tomatoes at various temperatures. Four Salmonella serotypes (Typhimurium, Newport, Javiana, and Braenderup) obtained from previous tomato-linked cases of salmonellosis were used in this study. These four serotypes were cultured separately, combined into a cocktail, and inoculated onto whole red round tomatoes and allowed to dry overnight. The tomatoes were then cut into pieces and incubated at a predetermined range of temperatures (10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, and 35°C). Salmonella concentration was measured at specified time intervals to determine the growth curve for Salmonella on cut tomatoes at each temperature. The growth rates were calculated using DMFit and used to build a mathematical model to illustrate the relationship between the growth rates of Salmonella on tomatoes and incubation temperatures from 10 to 35°C. The resulting model compared favorably with a Salmonella growth model for raw poultry developed by our laboratory. The Pathogen Modeling Program underpredicted growth at low temperatures and overpredicted growth at high temperatures. ComBase predicted consistently slower growth rates than were observed in tomatoes but showed parallel increases in growth rate with increasing temperature.

scholarly journals Growth of Listeria monocytogenes in Thawed Frozen Foods

2017 ◽  
Vol 80 (3) ◽  
pp. 447-453 ◽  
Author(s):  
Ai Kataoka ◽  
Hua Wang ◽  
Philip H. Elliott ◽  
Richard C. Whiting ◽  
Melinda M. Hayman
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Growth Rates ◽  
Storage Temperature ◽  
Growth Parameters ◽  
Quadratic Model ◽  
Lag Phase ◽  
Frozen Foods ◽  
Phase Duration ◽  
Primary Model

ABSTRACT The growth characteristics of Listeria monocytogenes inoculated onto frozen foods (corn, green peas, crabmeat, and shrimp) and thawed by being stored at 4, 8, 12, and 20°C were investigated. The growth parameters, lag-phase duration (LPD) and exponential growth rate (EGR), were determined by using a two-phase linear growth model as a primary model and a square root model for EGR and a quadratic model for LPD as secondary models, based on the growth data. The EGR model predictions were compared with growth rates obtained from the USDA Pathogen Modeling Program, calculated with similar pH, salt percentage, and NaNO2 parameters, at all storage temperatures. The results showed that L. monocytogenes grew well in all food types, with the growth rate increasing with storage temperature. Predicted EGRs for all food types demonstrated the significance of storage temperature and similar growth rates among four food types. The predicted EGRs showed slightly slower rate compared with the values from the U.S. Department of Agriculture Pathogen Modeling Program. LPD could not be accurately predicted, possibly because there were not enough sampling points. These data established by using real food samples demonstrated that L. monocytogenes can initiate growth without a prolonged lag phase even at refrigeration temperature (4°C), and the predictive models derived from this study can be useful for developing proper handling guidelines for thawed frozen foods during production and storage.

scholarly journals A Mathematical Model of anIn VitroExperiment to Investigate Endothelial Cell Migration

2002 ◽  
Vol 4 (4) ◽  
pp. 251-270 ◽  
Author(s):  
M. J. Plank ◽  
B. D. Sleeman ◽  
P. F. Jones
Keyword(s):  
Mathematical Model ◽  
Cell Migration ◽  
Endothelial Cell ◽  
Blood Vessels ◽  
Three Dimensional ◽  
Cell Movement ◽  
Quantitative Model ◽  
Angiogenic Factors ◽  
Endothelial Cell Migration ◽  
Angiogenic Factor

Angiogenesis, the growth of new blood vessels from existing ones, is an important, yet not fully understood, process and is involved in diseases such as rheumatoid arthritis, diabetic retinopathy and solid tumour growth. Central to the process of angiogenesis are endothelial cells (EC), which line all blood vessels, and are capable of forming new capillaries by migration, proliferation and lumen formation. We construct a cell-based mathematical model of an experiment (Vernon, R.B. and Sage, E.H. (1999) “A novel, quantitative model for study of endothelial cell migration and sprout formation within three-dimensional collagen matrices”,Microvasc. Res.57, 118–133) carried out to assess the response of EC to various diffusible angiogenic factors, which is a crucial part of angiogenesis. The model for cell movement is based on the theory of reinforced random walks and includes both chemotaxis and chemokinesis. Three-dimensional simulations are run and the results correlate well with the experimental data. The experiment cannot easily distinguish between chemotactic and chemokinetic effects of the angiogenic factors. We, therefore, also run two-dimensional simulations of a hypothetical experiment, with a point source of angiogenic factor. This enables directed (gradient-driven) EC migration to be investigated independently of undirected (diffusion-driven) migration.

Biomass Reduction and Mineralization Increase Due to the Ciliate Tetrahymena pyriformis Grazing on the Bacterium Pseudomonas fluorescens

1994 ◽  
Vol 29 (7) ◽  
pp. 119-128 ◽  
Author(s):  
C. H. Ratsak ◽  
B. W. Kooi ◽  
H. W. van Verseveld
Keyword(s):  
Growth Rates ◽  
Growth Parameters ◽  
Waste Water Treatment ◽  
High Growth ◽  
Tetrahymena Pyriformis ◽  
Lower Growth ◽  
Purification Efficiency ◽  
High Purification ◽  
Biomass Reduction ◽  
Sludge Production

The currently high sludge production and increasing processing costs call for waste-water treatment plants with high purification efficiency and low biomass production. We studied the latter issue through two-stage chemostat cascades to assess the overall biomass reduction due to ciliate grazing. The bacteria were cultured in the first chemostat whereas the ciliates, grazing on the bacteria from the first chemostat, were cultured in the second chemostat. Mathematical modelling was used to describe the bacteria/ciliate dynamics and some of the growth parameters were fitted. In the second chemostat 22-44% of the carbon originating from the first chemostat was mineralized to CO2. An extra biomass reduction of 12-43% was possible due to grazing by the ciliates. At lower growth rates of the ciliates the extra biomass reduction was higher than at high growth rates. This finding is auspicious, suggesting that predator organisms indeed can reduce sludge production.

scholarly journals Age and growth variability of the yellow clam (Mesodesma mactroides) in two populations from Argentina: implications under climate change

2020 ◽  
Vol 98 (7) ◽  
pp. 481-494
Author(s):  
M.C. Risoli ◽  
A. Baldoni ◽  
J. Giménez ◽  
B.J. Lomovasky
Keyword(s):  
Climate Change ◽  
Cross Sections ◽  
Growth Rates ◽  
Growth Parameters ◽  
Shell Growth ◽  
Condition Index ◽  
Age And Growth ◽  
Shell Mass ◽  
Growth Variability ◽  
Two Populations

Morphometric relationships and age and growth rates of the yellow clam (Mesodesma mactroides Reeve, 1854 = Amarilladesma mactroides (Reeve, 1854)) were compared in two populations from Argentina: Santa Teresita (36°32′00″S) and Mar del Plata (37°57′52″S). The Santa Teresita clams were heavier (shell, soft parts) than the Mar del Plata clams. Cross sections stained with Mutvei’s solution and acetate peels revealed an internal shell growth pattern of well-defined slow-growing translucent bands and alternating fast-growing opaque bands. Translucent bands (clusters) representing external rings were formed mostly during October in both sites, coinciding with gonadal maturation processes and spawning. Data confirm the annual formation of translucent bands in this species. Comparison of growth parameters showed a higher growth rate k and lower maximum age in Mar del Plata (8 years) than in Santa Teresita (9 years), which could be triggered by differences in salinity between localities due to the influence of the Rio de la Plata estuary, which is strongly linked to climate variability. Shell mass condition index and Oceanic Niño Index were negatively correlated, showing the influence of El Niño in shell properties of the species. Considering that events are becoming more intense and frequent, changes in growth rates and shell properties of Santa Teresita’s population could be expected to be more vulnerable under climate change.

scholarly journals The Army and the Spread of Roman Citizenship

2019 ◽  
Vol 109 ◽  
pp. 27-69
Author(s):  
Myles Lavan
Keyword(s):  
Mathematical Model ◽  
Analytical Method ◽  
Family Formation ◽  
Quantitative Model ◽  
Length Of Service ◽  
Supplementary Appendix ◽  
Recent Advances ◽  
Supplementary Material ◽  
Over Time

AbstractThis paper draws on recent advances in our knowledge (much of it owed to the proliferation of military diplomas) and a new analytical method to quantify the number of soldiers and their children who received Roman citizenship between 14 and 212 c.e. Although significant uncertainties remain, these can be quantified and turn out to be small relative to the overall scale of enfranchisement. The paper begins by reviewing what is known about grants of citizenship to soldiers, with particular attention to the remaining uncertainties, before presenting a quantitative model of the phenomenon. The total number of beneficiaries was somewhere in the region 0.9–1.6 million — significantly lower than previous estimates have suggested. It also emerges that the rate of enfranchisement varied substantially over time, in line with significant changes in manpower, length of service (and hence the number of recruits and discharged veterans) and the rate of family formation among soldiers. The Supplementary Material available online (https://doi.org/10.1017/S0075435819000662) contains a database of military diplomas (Supplementary Appendix 1), a mathematical model of enfranchisement implemented in MS Excel (Supplementary Appendix 2), a description of the model (Supplementary Appendix 3A) and a derivation of the model of attrition across service cohorts in Fig. 6 (Supplementary Appendix 3B).

scholarly journals 4168 Understanding ECM-Based Drug Resistivity in Breast Cancer

2020 ◽  
Vol 4 (s1) ◽  
pp. 113-114
Author(s):  
Sarah Libring ◽  
Aparna Shinde ◽  
Miad Boodaghidizaji ◽  
Alexandra Plummer ◽  
Arezoo Ardekani ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Mathematical Model ◽  
Transport Properties ◽  
Growth Rates ◽  
Cellular Response ◽  
Drug Sensitivity ◽  
Survival Rates ◽  
Cell Junctions ◽  
Matrix Interactions ◽  
Cell Cell

OBJECTIVES/GOALS: Cell-cell (CC) and cell-matrix interactions (CM) are known to affect drug sensitivity of cancer cells, but are not effectively recapitulated using 2D platforms. This research aims to determine how cell and matrix interactions confer drug resistivity in 3 distinct culturing models: 2D (no CM/limited CC), 3D spheroids (CC) and 3D fibronectin (both). METHODS/STUDY POPULATION: We examined four breast cancer cell types. The cells were derived from a nonmetastatic primary tumor (HMLE-E2) or overt bone-metastasis (BM). Transglutaminase 2 (TGM2), a matrix crosslinking protein, is overexpressed in metastatic bone tumors and may play a key role in matrix-conferred drug resistivity. In a gain-of-function model, TGM2 was upregulated in HMLE-E2 cells and compared to shTGM2 knockdown BM cells. Growth rates were analyzed using metabolic activity over 8 days, and drug sensitivity to Neratinib (0-1000 nM) was analyzed via cell titer. To account for the different transport properties of the 3 distinct culture environments, we developed a mathematical model for each condition, allowing us to normalize the drug sensitivity results across models to effectively compare true biological resistivity. RESULTS/ANTICIPATED RESULTS: We observed that increased cellular levels of TGM2 significantly increase the growth rate and drug resistivity of cells on fibronectin matrices. Interestingly, in 2D cultures, TGM2 expression was correlated with higher Neratinib resistivity but did not affect growth rates. In spheroid models without a significant matrix component, that rely solely on cell-cell junctions, high levels of TGM2 were correlated with lower survival rates. Lower levels of TGM2 are correlated with a more epithelial phenotype, and using our mathematical model we have identified significant transport differences between high and low TGM2 spheroids. We theorize that the low TGM2 spheroids have denser packing, which lowers the rate of diffusion and, thus reduces the effective concentration of the drug to the majority of the cells. DISCUSSION/SIGNIFICANCE OF IMPACT: Our studies indicate that the cellular response to drugs can be altered by changes in both transport properties of the tissue and the CM interactions. By systematically investigating the effects of CC interactions and CM interactions, we can use mathematical models to delineate physical means of drug resistivity from a biologically driven resistance.

Heteroblastic seedlings of green ash. I. Predictability of leaf form and primordial length

1986 ◽  
Vol 64 (11) ◽  
pp. 2645-2649 ◽  
Author(s):  
E. K. Merrill
Keyword(s):  
Leaf Development ◽  
Leaf Growth ◽  
Leaf Primordia ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Leaf Form ◽  
Compound Leaf ◽  
Controlled Conditions ◽  
Plastochron Index

Green ash (Fraxinus pennsylvanica var. subintegerrima) seedlings are heteroblastic; during development they produce two types of leaves, simple and compound. When grown under controlled conditions, the sequence of leaf types is predictable. Simple leaves are always at the first four nodes; compound leaves are always at node 8 and above. Nodes 5 through 7 have progressively fewer simple leaves and more compound leaves. Leaf growth on seedlings meets the preconditions of the plastochron index and leaf plastochron index. These indices, as well as the length of single expanding leaves, can be used to predict lengths of leaf primordia at nodes 4 and 8 so that early, simple and compound leaf development can be compared in further studies of green ash.

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