A MODEL OF THE RELATIONSHIP BETWEEN MELANOCYTES AND LANGERHANS CELLS. Melanocyte Population Dynamics

1967 ◽  
Vol 79 (1) ◽  
pp. 52-58 ◽  
Author(s):  
P. A. RILEY
Keyword(s):  
Population Dynamics ◽  
Langerhans Cells ◽  
The Relationship

scholarly journals Lightning Damage Facilitates Beetle Colonization of Tropical Trees

2020 ◽  
Author(s):  
Brady P Parlato ◽  
Evan M Gora ◽  
Stephen P Yanoviak
Keyword(s):  
Population Dynamics ◽  
Tropical Forest ◽  
Forest Ecosystems ◽  
Tropical Trees ◽  
Pine Forests ◽  
Forest Trees ◽  
Beetle Population ◽  
Tree Diameter ◽  
Crown Dieback ◽  
The Relationship

Abstract Lightning is a common agent of disturbance in many forest ecosystems. Lightning-damaged trees are a potentially important resource for beetles, but most evidence for this association is limited to temperate pine forests. Here, we evaluated the relationship between lightning damage and beetle colonization of tropical trees. We recorded the number of beetle holes on the trunks of trees from 10 strike sites (n = 173 lightning-damaged trees) and 10 matching control sites (n = 137 control trees) in Panama. The trunks of lightning-struck trees had 370% more beetle holes than control trees. The abundance of beetle holes increased with increasing total crown dieback among both control and lightning-damaged trees, and with larger tree diameter among lightning-struck trees. Beetle holes also were more abundant in trunk sections of lightning-damaged trees located directly below a damaged section of the crown. The results of this study suggest that lightning damage facilitates beetle colonization in tropical forest trees and provide a basis for investigations of the effects of lightning-caused disturbance on beetle population dynamics and assemblage structure.

The Relationship between Population Dynamics and Urban Hierarchy

2014 ◽  
Vol 37 (2) ◽  
pp. 149-171 ◽  
Author(s):  
Joao F. Bigotte ◽  
Antonio P. Antunes ◽  
Dmitry Krass ◽  
Oded Berman
Keyword(s):  
Population Dynamics ◽  
Urban Hierarchy ◽  
The Relationship

The Relationship of Spathimeigenia spinigera Townsend (Diptera: Tachinidae) to its Host, Neodiprion swainei Midd. (Hymenoptera: Diprionidae)

1962 ◽  
Vol 94 (8) ◽  
pp. 809-818 ◽  
Author(s):  
H. A. Tripp
Keyword(s):  
Population Dynamics ◽  
Pinus Banksiana ◽  
Jack Pine ◽  
Immature Stages ◽  
Pine Sawfly ◽  
Factors Influencing ◽  
Form Part ◽  
Extensive Program ◽  
Relationship Of ◽  
The Relationship

Studies on the parasites of the Swaine jack pine sawfly, Neodiprion swainei Midd., form part of an extensive program designed to assess the factors influencing population dynamics of this important defoliator of jack pine, Pinus banksiana Lamb. Investigations were carried out in the Province of Quebec between 1955 and 1959 near the headwaters of the Gatineau River, Abitibi County, and continued during 1960 and 1961 near the source of the Vermillion River, County Laviolette. In both areas, one of the principal parasites associated with N. swainei was the tachinid, Spathimeigenia spinigera Townsend. Descriptions of the immature stages of this parasite, and details of its behaviour were published previously (Tripp, 1960).

scholarly journals Spatially cascading effect of perturbations in experimental meta-ecosystems

2016 ◽  
Vol 283 (1838) ◽  
pp. 20161496 ◽  
Author(s):  
Eric Harvey ◽  
Isabelle Gounand ◽  
Pravin Ganesanandamoorthy ◽  
Florian Altermatt
Keyword(s):  
Population Dynamics ◽  
Community Dynamics ◽  
Local Community ◽  
Local Population ◽  
Temporal Variations ◽  
Landscape Scale ◽  
Cascading Effect ◽  
Regional Dynamics ◽  
The Relationship ◽  
Over Time

Ecosystems are linked to neighbouring ecosystems not only by dispersal, but also by the movement of subsidy. Such subsidy couplings between ecosystems have important landscape-scale implications because perturbations in one ecosystem may affect community structure and functioning in neighbouring ecosystems via increased/decreased subsidies. Here, we combine a general theoretical approach based on harvesting theory and a two-patch protist meta-ecosystem experiment to test the effect of regional perturbations on local community dynamics. We first characterized the relationship between the perturbation regime and local population demography on detritus production using a mathematical model. We then experimentally simulated a perturbation gradient affecting connected ecosystems simultaneously, thus altering cross-ecosystem subsidy exchanges. We demonstrate that the perturbation regime can interact with local population dynamics to trigger unexpected temporal variations in subsidy pulses from one ecosystem to another. High perturbation intensity initially led to the highest level of subsidy flows; however, the level of perturbation interacted with population dynamics to generate a crash in subsidy exchange over time. Both theoretical and experimental results show that a perturbation regime interacting with local community dynamics can induce a collapse in population levels for recipient ecosystems. These results call for integrative management of human-altered landscapes that takes into account regional dynamics of both species and resource flows.

The relationship between soybean cyst nematode seasonal population dynamics and soil texture

Nematology ◽  
2004 ◽  
Vol 6 (4) ◽  
pp. 511-525 ◽  
Author(s):  
Felicitas Avendaño ◽  
Francis J. Ierce ◽  
Haddish Melakeberhan
Keyword(s):  
Population Dynamics ◽  
Soil Texture ◽  
Soybean Cyst Nematode ◽  
Reproductive Potential ◽  
Cyst Nematode ◽  
Stable Relationship ◽  
Wide Range ◽  
The Relationship ◽  
Seasonal Population ◽  
Seasonal Population Dynamics

Abstract The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, cyst population densities at planting and at harvest have been related to soil texture but the seasonal mechanisms by which these correlations are established are less well known. The purpose of this work was to analyse the relationship of SCN life stages and reproductive potential (number of eggs per cyst) with soil texture. Cyst population density was positively correlated with sand and negatively correlated with clay and silt percentage in the soil within the ranges of 45-80% sand, 8-23% clay, and 8-43% silt in one field, but not in the other at five sampling times. The relationship between soil texture and juvenile stages in roots was weak. The stable relationship between SCN spatial and seasonal population dynamics and soil properties provides further support for potential delineation of management zones in SCN infested fields with a wide range of soil textures.

scholarly journals Inoculum Density-Disease Development Relationship in Verticillium Wilt of Artichoke Caused by Verticillium dahliae

Plant Disease ◽  
2007 ◽  
Vol 91 (9) ◽  
pp. 1131-1136 ◽  
Author(s):  
M. Berbegal ◽  
A. Ortega ◽  
J. García-Jiménez ◽  
J. Armengol
Keyword(s):  
Population Dynamics ◽  
Verticillium Dahliae ◽  
Symptom Severity ◽  
Disease Incidence ◽  
Growing Season ◽  
Inoculum Density ◽  
Disease Development ◽  
Growing Seasons ◽  
Negative Exponential ◽  
The Relationship

The relationship between inoculum density of Verticillium dahliae in soil and disease development was studied in 10 commercial artichoke fields. Inoculum density of V. dahliae varied between 2.2 and 34.2 microsclerotia (ms) g–1 of soil near planting. Artichoke plants were monitored for disease at the beginning and the end of each growing season. There was a significant correlation, which was best described by negative exponential models, between inoculum density and disease incidence, symptom severity, and recovery of the pathogen from the plants. Inoculum densities ranging from 5 to 9 ms g–1 of soil were associated with a mean percentage of infected plants of about 50%. Additionally, three fields were monitored in two consecutive growing seasons to evaluate the population dynamics of V. dahliae microsclerotia in soil and disease development. Numbers of microsclerotia per gram of soil decreased significantly by the end of the first growing season but slightly increased at the end of the second growing season. In these fields, symptom severity was greatest during the second growing season when high percentages of infected plants also were recorded.

The Origin and Function of Langerin (CD207) Expressing Cells in Mice and Humans

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. SCI-7-SCI-7
Author(s):  
Miriam Merad
Keyword(s):  
Dendritic Cell ◽  
Langerhans Cells ◽  
Conflicts Of Interest ◽  
Langerhans Cell ◽  
Cell Lineages ◽  
Long Time ◽  
And Function ◽  
Relationship Of ◽  
Epidermal Dendritic Cells ◽  
The Relationship

Abstract Abstract SCI-7 The current paradigm suggests that Langerhans cell histiocytosis (LCH) results from an accumulation of epidermal dendritic cells also called Langerhans cells. This concept is based on phenotypic and ultrastructural observations showing that LCH lesions are infiltrated by CD1a+langerin+ cells, two features thought to be restricted to epidermal Langerhans cells. It has been difficult, however, to understand how Langerhans cells, which are normally restricted to stratified epithelia, could give rise to such a multifocal disorder. LCH research has been handicapped by the inability to develop reliable animal models and by the fact that for a long time very few markers were available to determine the origin and stage of differentiation of histiocytes, now renamed macrophage/dendritic cell lineages. This presentation will discuss recent progress in our understanding of the regulation of the Langerhans cell, macrophage, and dendritic cell lineages and discuss the relationship of these lineages with the LCH cell. Disclosures: No relevant conflicts of interest to declare.

Research on the Physiological Basis of Population Dynamics in Relation to Ecotoxicology

1987 ◽  
Vol 19 (11) ◽  
pp. 21-37 ◽  
Author(s):  
S A. L. M. Kooijman ◽  
A. O. Hanstveit ◽  
N. van der Hoeven
Keyword(s):  
Population Dynamics ◽  
Simulation Studies ◽  
Nutrient Budgets ◽  
Physiological Basis ◽  
Computer Simulation Studies ◽  
Freshwater Plankton ◽  
The Relationship ◽  
Insight Into ◽  
Made In

One of the main obstacles that hampers ecotoxlcology is the poor insight into the relationship between physiological and population dynamics. The role of laboratory experiments, modeling, mathematical analysis and computer simulation studies is discussed in research aiming at this relation. Energy and nutrient budgets of organisms are found to be of vital importance. This paper evaluates the progress that has been made in concrete efforts to work out energy and nutrient budgets for simple freshwater plankton systems stressed by toxic chemicals with different modes of action.

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