Changes in Spatial Pattern of an Intertidal Population of the Nudibranch Mollusc Onchidoris muricata in Relation to Life-Cycle, Mortality and Environmental Heterogeneity

Abstract The spatial pattern of species is an important feature to understand why these species coexist and remain in position or not, and using the single Ripley function and the L(r) function, we analyzed the spatial pattern of types of broad-leaf tree and tree covers and the needles for mixed brawls in the forests of Mount Gara, using PASSAGE V.2, L(r) analysis of the species under study showed a variation in the pattern distribution of trees and gave the highest percentage of random form distribution pattern with a cluster pattern of 11.25%, Through the ratios and forms of distribution of the L(r) function of the various samples of the study, we find that these stands generally tend to be regular, indicating that these species remain at the end of the life cycle in the structure of a more stable stand.

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The Biology of Eurydice Pulchra [Crustacea: Isopoda]

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400005026 ◽

1970 ◽

Vol 50 (3) ◽

pp. 753-768 ◽

Cited By ~ 32

Author(s):

Susan Fish

Keyword(s):

Population Structure ◽

Life Cycle ◽

West Coast ◽

Sandy Beaches ◽

British Isles ◽

The West ◽

Intertidal Population ◽

Made In

Eurydice pulchra Leach is a common intertidal isopod of sandy beaches. Its occurrence around the British Isles has been described by Jones & Naylor (1967), and Salvat (1966) has described the life cycle and intertidal distribution of the species on the west coast of France. There are several records of its intertidal distribution in Britain (Elmhirst, 1931; Pirrie, Bruce & Moore, 1932; Rees, 1939; Watkin, 1942; Brady, 1942; Holme, 1949; Southward, 1953; Colman & Segrove, 1955; Perkins, 1956; M. Ladle, unpublished) and these suggest that its distribution is variable. Watkin (1942) found that the population structure of E. pulchra in late March and early April was comprised of ‘two distinct groups’ and similar findings were made in July by Scott (1960). The present study was made on a large intertidal population in the sands of the Dovey Estuary, Cardinganshire.

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Modelling the effects of environmental heterogeneity within the lung on the tuberculosis life-cycle

Journal of Theoretical Biology ◽

10.1016/j.jtbi.2020.110381 ◽

2020 ◽

Vol 506 ◽

pp. 110381

Author(s):

Michael J. Pitcher ◽

Ruth Bowness ◽

Simon Dobson ◽

Raluca Eftimie ◽

Stephen H. Gillespie

Keyword(s):

Life Cycle ◽

Environmental Heterogeneity

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Modelling the effects of environmental heterogeneity within the lung on the tuberculosis life-cycle

10.1101/2019.12.12.871269 ◽

2019 ◽

Author(s):

Michael J. Pitcher ◽

Ruth Bowness ◽

Simon Dobson ◽

Raluca Eftimie ◽

Stephen H. Gillespie

Keyword(s):

Life Cycle ◽

Environmental Heterogeneity ◽

Adaptive Immune Response ◽

Blood Perfusion ◽

Initial Infection ◽

Latent Stage ◽

Environmental Attributes ◽

Air Ventilation ◽

Alveolar Tissue ◽

Disease Stages

AbstractProgress in shortening the duration of tuberculosis (TB) treatment is hampered by the lack of a predictive model that accurately reflects the diverse environment within the lung. This is important as TB has been shown to produce distinct localisations to different areas of the lung during different disease stages, with the environmental heterogeneity within the lung of factors such as air ventilation, blood perfusion and oxygen tension believed to contribute to the apical localisation witnessed during the post-primary form of the disease.Building upon our previous model of environmental lung heterogeneity, we present a networked metapopulation model that simulates TB across the whole lung, incorporating these notions of environmental heterogeneity across the whole TB life-cycle to show how different stages of the disease are influenced by different environmental and immunological factors. The alveolar tissue in the lung is divided into distinct patches, with each patch representing a portion of the total tissue and containing environmental attributes that reflect the internal conditions at that location. We include populations of bacteria and immune cells in various states, and events are included which determine how the members of the model interact with each other and the environment. By allowing some of these events to be dependent on environmental attributes, we create a set of heterogeneous dynamics, whereby the location of the tissue within the lung determines the disease pathological events that occur there.Our results show that the environmental heterogeneity within the lung is a plausible driving force behind the apical localisation during post-primary disease. After initial infection, bacterial levels will grow in the initial infection location at the base of the lung until an adaptive immune response is initiated. During this period, bacteria are able to disseminate and create new lesions throughout the lung. During the latent stage, the lesions that are situated towards the apex are the largest in size, and once a post-primary immune-suppressing event occurs, it is the uppermost lesions that reach the highest levels of bacterial proliferation. Our sensitivity analysis also shows that it is the differential in blood perfusion, causing reduced immune activity towards the apex, which has the biggest influence of disease outputs.

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Spatial pattern of intraspecific trait variability in Sphagnum fuscum

Botany ◽

10.1139/cjb-2020-0077 ◽

2020 ◽

Vol 98 (12) ◽

pp. 717-723

Author(s):

Tobi A. Oke ◽

M.R. Turetsky

Keyword(s):

Spatial Pattern ◽

Intraspecific Variation ◽

Environmental Heterogeneity ◽

Spatial Scales ◽

Intraspecific Variability ◽

Sphagnum Moss ◽

Hierarchical Design ◽

Ecological Processes ◽

Sphagnum Fuscum ◽

Intraspecific Trait Variability

Recent studies have shown that intraspecific variability is a mechanism by which species respond to environmental heterogeneity, and that intraspecific variation can have large implications for ecological processes. Here, we studied whether there is meaningful intraspecific variation in the ecohydrological traits, biomass allocation, and decomposability in Sphagnum moss, and if so, to explore the spatial pattern of variability. We implemented a hierarchical design in which we quantified traits of S. fuscum at three spatial scales: (i) between individuals within 8 cm2 patches; (ii) between replicate patches located within a single hummock or hollow location; and (iii) between hummocks. Although we focused on S. fuscum, we also compared the variability in some morphological features of S. fuscum and S. magellanicum. If growth is affected by density, we expected variability to be lowest at the patch level. Contrary to our expectation, most of the variability in both species occurred within-patch, which is our smallest sampling unit. Variability was generally higher in the traits for S. magellanicum compared with the variability in the traits for S. fuscum, which was generally negligible. Also, the pattern of variability observed for some of the traits such as the capitulum mass suggests that the mechanisms controlling different traits may be operating at different spatial scales.

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Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156791 ◽

1989 ◽

Vol 47 ◽

pp. 962-963

Author(s):

Betty Ruth Jones ◽

Steve Chi-Tang Pan

Keyword(s):

Nervous System ◽

Life Cycle ◽

Schistosoma Mansoni ◽

Snail Host ◽

Complex Life Cycle ◽

Rational Approach ◽

Effective Control ◽

The Social ◽

Social And Economic Development ◽

Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

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A freeze-fracture-etched study of the physarum polycephalum plasma membrane during early formation of the macroplasmodial stage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147570 ◽

1993 ◽

Vol 51 ◽

pp. 346-347

Author(s):

Randolph W. Taylor ◽

Henrie Treadwell

Keyword(s):

Plasma Membrane ◽

Life Cycle ◽

Growth Phase ◽

Filter Paper ◽

Physarum Polycephalum ◽

Freeze Fracture ◽

Petri Dish ◽

Wire Screen ◽

Wide Mouth ◽

Sterile Filter

The plasma membrane of the Slime Mold, Physarum polycephalum, process unique morphological distinctions at different stages of the life cycle. Investigations of the plasma membrane of P. polycephalum, particularly, the arrangements of the intramembranous particles has provided useful information concerning possible changes occurring in higher organisms. In this report Freeze-fracture-etched techniques were used to investigate 3 hours post-fusion of the macroplasmodia stage of the P. polycephalum plasma membrane.Microplasmodia of Physarum polycephalum (M3C), axenically maintained, were collected in mid-expotential growth phase by centrifugation. Aliquots of microplasmodia were spread in 3 cm circles with a wide mouth pipette onto sterile filter paper which was supported on a wire screen contained in a petri dish. The cells were starved for 2 hrs at 24°C. After starvation, the cells were feed semidefined medium supplemented with hemin and incubated at 24°C. Three hours after incubation, samples were collected randomly from the petri plates, placed in plancettes and frozen with a propane-nitrogen jet freezer.

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