An Age-Dependent Branching Process with Correlations Among Sister Cells

1969 ◽  
Vol 6 (01) ◽  
pp. 205-210 ◽  
Author(s):  
Kenny S. Crump ◽  
J. Charles Mode
Keyword(s):  
Branching Process ◽  
Cell Populations ◽  
Bacterial Populations ◽  
Positive Correlation ◽  
Daughter Cells ◽  
Age Dependent ◽  
Mother And Daughter ◽  
Positive Correlations ◽  
Sister Cells

In this note we consider an age-dependent branching process in which the life-spans of sister cells are correlated as well as the numbers of offspring of sister cells, but otherwise cells live and reproduce independently. One might surmise that in many populations there would be some positive correlation among siblings due to similar characteristics inherited from parents. Data of Powell (1955) seem to corroborate this conjecture. Powell's data indicate that in certain bacterial populations the life-spans of sister cells have significant positive correlations while the correlation between the life-spans of mother and daughter cells is negligible. More recently positive correlations have been observed in cell populations among the life-spans of first cousins and also among second cousins (Kubitschek (1967)). However, the model presented in this note permits correlations only among siblings.

An Age-Dependent Branching Process with Correlations Among Sister Cells

1969 ◽  
Vol 6 (1) ◽  
pp. 205-210 ◽  
Author(s):  
Kenny S. Crump ◽  
J. Charles Mode
Keyword(s):  
Branching Process ◽  
Cell Populations ◽  
Bacterial Populations ◽  
Positive Correlation ◽  
Daughter Cells ◽  
Age Dependent ◽  
Mother And Daughter ◽  
Positive Correlations ◽  
Sister Cells

In this note we consider an age-dependent branching process in which the life-spans of sister cells are correlated as well as the numbers of offspring of sister cells, but otherwise cells live and reproduce independently. One might surmise that in many populations there would be some positive correlation among siblings due to similar characteristics inherited from parents. Data of Powell (1955) seem to corroborate this conjecture. Powell's data indicate that in certain bacterial populations the life-spans of sister cells have significant positive correlations while the correlation between the life-spans of mother and daughter cells is negligible. More recently positive correlations have been observed in cell populations among the life-spans of first cousins and also among second cousins (Kubitschek (1967)). However, the model presented in this note permits correlations only among siblings.

Extensions of the bifurcating autoregressive model for cell lineage studies

1999 ◽  
Vol 36 (04) ◽  
pp. 1225-1233 ◽  
Author(s):  
R. M. Huggins ◽  
I. V. Basawa
Keyword(s):  
Environmental Effects ◽  
Autoregressive Model ◽  
Cell Lineage ◽  
Data Sets ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Model Cell ◽  
Lines Of Descent ◽  
Lineage Trees ◽  
Sister Cells

The bifurcating autoregressive model has been used previously to model cell lineage data. A feature of this model is that each line of descendants from an initial cell follows an AR(1) model, and that the environmental effects on sisters are correlated. However, this model concentrates on modelling the correlations between mother and daughter cells and between sister cells, and does not explain the large correlations between more distant relatives observed by some authors. Here the model is extended, firstly by allowing lines of descent to follow an ARMA(p,q) model rather than an AR(1) model, and secondly by allowing correlations between the environmental effects of relatives more distant than sisters. The models are applied to several data sets consisting of independent cell lineage trees.

Extensions of the bifurcating autoregressive model for cell lineage studies

1999 ◽  
Vol 36 (4) ◽  
pp. 1225-1233 ◽  
Author(s):  
R. M. Huggins ◽  
I. V. Basawa
Keyword(s):  
Environmental Effects ◽  
Autoregressive Model ◽  
Cell Lineage ◽  
Data Sets ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Model Cell ◽  
Lines Of Descent ◽  
Lineage Trees ◽  
Sister Cells

The bifurcating autoregressive model has been used previously to model cell lineage data. A feature of this model is that each line of descendants from an initial cell follows an AR(1) model, and that the environmental effects on sisters are correlated. However, this model concentrates on modelling the correlations between mother and daughter cells and between sister cells, and does not explain the large correlations between more distant relatives observed by some authors. Here the model is extended, firstly by allowing lines of descent to follow an ARMA(p,q) model rather than an AR(1) model, and secondly by allowing correlations between the environmental effects of relatives more distant than sisters. The models are applied to several data sets consisting of independent cell lineage trees.

scholarly journals Solid-phase inclusion as a mechanism for regulating unfolded proteins in the mitochondrial matrix

2020 ◽  
Vol 6 (32) ◽  
pp. eabc7288
Author(s):  
Linhao Ruan ◽  
Joshua T. McNamara ◽  
Xi Zhang ◽  
Alexander Chih-Chieh Chang ◽  
Jin Zhu ◽  
...  
Keyword(s):  
Solid Phase ◽  
Tricarboxylic Acid Cycle ◽  
Yeast Cells ◽  
Mitochondrial Proteins ◽  
Mitochondrial Matrix ◽  
Unfolded Proteins ◽  
Daughter Cells ◽  
Contact Sites ◽  
Age Dependent ◽  
Mother And Daughter

Proteostasis declines with age, characterized by the accumulation of unfolded or damaged proteins. Recent studies suggest that proteins constituting pathological inclusions in neurodegenerative diseases also enter and accumulate in mitochondria. How unfolded proteins are managed within mitochondria remains unclear. Here, we found that excessive unfolded proteins in the mitochondrial matrix of yeast cells are consolidated into solid-phase inclusions, which we term deposits of unfolded mitochondrial proteins (DUMP). Formation of DUMP occurs in mitochondria near endoplasmic reticulum–mitochondria contact sites and is regulated by mitochondrial proteins controlling the production of cytidine 5′-diphosphate–diacylglycerol. DUMP formation is age dependent but accelerated by exogenous unfolded proteins. Many enzymes of the tricarboxylic acid cycle were enriched in DUMP. During yeast cell division, DUMP formation is necessary for asymmetric inheritance of damaged mitochondrial proteins between mother and daughter cells. We provide evidence that DUMP-like structures may be induced by excessive unfolded proteins in human cells.

Conditions for Positive and Negative Correlations Between Fitness and Heterozygosity in Equilibrium Populations

Genetics ◽  
1998 ◽  
Vol 148 (3) ◽  
pp. 1333-1340 ◽  
Author(s):  
Hong-Wen Deng ◽  
Yun-Xin Fu
Keyword(s):  
Single Population ◽  
Positive Correlation ◽  
Genetic Explanation ◽  
Genetic Causes ◽  
The Past ◽  
Fitness Traits ◽  
Genetic Systems ◽  
Positive Correlations ◽  
Non Equilibrium

AbstractThe past decades have witnessed extensive efforts to correlate fitness traits with genomic heterozygosity. While positive correlations are revealed in most of the organisms studied, results of no/negative correlations are not uncommon. There has been little effort to reveal the genetic causes of these negative correlations. The positive correlations are regarded either as evidence for functional overdominance in large, randomly mating populations at equilibrium, or the results of populations at disequilibrium under dominance. More often, the positive correlations are viewed as a phenomenon of heterosis, so that it cannot possibly occur under within-locus additive allelic effects. Here we give exact genetic conditions that give rise to positive and negative correlations in populations at Hardy-Weinberg and linkage equilibria, thus offering a genetic explanation for the observed negative correlations. Our results demonstrate that the above interpretations concerning the positive correlations are not complete or even necessary. Such a positive correlation can result under dominance and potentially under additivity, even in populations where associated overdominance due to linked alleles at different loci is not significant. Additionally, negative correlations and heterosis can co-occur in a single population. Although our emphasis is on equilibrium populations and for biallelic genetic systems, the basic conclusions are generalized to non-equilibrium populations and for multi-allelic situations.

Branching processes and functional differential equations determining steady-size distributions in cell populations

1995 ◽  
Vol 32 (01) ◽  
pp. 1-10
Author(s):  
Ziad Taib
Keyword(s):  
Differential Equation ◽  
Branching Process ◽  
Branching Processes ◽  
Functional Differential Equations ◽  
Cell Populations ◽  
Size Distributions ◽  
Multitype Branching Process ◽  
Functional Differential ◽  
Intuitive Interpretation ◽  
Infinite Sum

The functional differential equation y′(x) = ay(λx) + by(x) arises in many different situations. The purpose of this note is to show how it arises in some multitype branching process cell population models. We also show how its solution can be given an intuitive interpretation as the probability density function of an infinite sum of independent but not identically distributed random variables.

Is Strategic Planning Worth the Effort? A Study of Firm Performance Versus Planning Comprehensiveness in Australia

2000 ◽  
Vol 6 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Peter Devenish ◽  
Tom Fisher
Keyword(s):  
Strategic Planning ◽  
Financial Performance ◽  
Statistical Tests ◽  
The United States ◽  
Negative Finding ◽  
Positive Correlation ◽  
Listed Firms ◽  
The United Kingdom ◽  
Weak Positive Correlation ◽  
Positive Correlations

AbstractThe planning-performance literature suggests that there is a weak positive correlation between strategic planning and financial performance. This study has been undertaken to determine whether this weak positive correlation is true for Australian firms.Strategic planning for the purposes of this study is arranged in three levels of planning complexity. A sample of 77 listed firms was surveyed to determine their level of planning complexity, and this was correlated with the firm's financial performance over a three year period.A range of statistical tests did not reveal any significant correlation between strategic planning at any of the three levels and the financial performance of the firm. This negative finding is generally in line with other recent studies conducted in Australia, the United States and the United Kingdom.However, positive correlations were found with several subjective performance measures, suggesting that respondents generally believe that strategic planning is helping their company.

A note on the subcritical generalized age-dependent branching process

1976 ◽  
Vol 13 (4) ◽  
pp. 798-803 ◽  
Author(s):  
R. A. Doney
Keyword(s):  
Branching Process ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Malthusian Parameter ◽  
Age Dependent ◽  
The Mean ◽  
Mean Function ◽  
Necessary And Sufficient

For a subcritical Bellman-Harris process for which the Malthusian parameter α exists and the mean function M(t)∼ aeat as t → ∞, a necessary and sufficient condition for e–at (1 –F(s, t)) to have a non-zero limit is known. The corresponding condition is given for the generalized branching process.

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