The selection of experimental doses and their importance for parasite success in metacercarial infection studies

SUMMARYExperimental studies of parasite transmission are essential for advances in basic and applied parasitology. A survey of the results of published experiments can identify the determinants of both variation among studies in experimental design and of parasite infection success. Here, analyses are conducted on data compiled from a total of 106 metacercarial infection experiments (35 on Echinostomatidae, 37 on Fasciolidae, 34 on other trematodes) obtained from 83 studies. All of these involved experimental oral infection of individual definitive hosts by a single known dose of metacercariae under controlled conditions. Across these studies, the metacercarial dose used (i) was typically about 10 times higher than the average natural dose that could be acquired by feeding on intermediate hosts (for taxa other than Fasciolidae), and (ii) showed a positive relationship with the body mass of the definitive host, although this relationship was only significant for Fasciolidae. Although the chosen dose was rarely justified, the larger the definitive host, the more metacercariae it received. Among Echinostomatidae and Fasciolidae, there was also a significant dose-dependent effect on infection success: the higher the dose used in an experiment, the smaller the proportion of metacercariae recovered from the host. This effect was mitigated by definitive host body mass, with infection success being generally lower in larger definitive hosts. For Echinostomatidae, the taxonomic identity of the definitive host also mattered, with metacercariae achieving higher infection success in mammals than in birds. The present findings suggest that the design of experimental infection studies requires greater consideration if their results are to yield useful biological insights.

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Practical Application of the Similarity Law of Structures in the Reconstruction of the Surface Layer of Bricks

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1017.21 ◽

2021 ◽

Vol 1017 ◽

pp. 21-30

Author(s):

Victor Danilov ◽

Arkady Ayzenshtadt ◽

Maria Frolova

Keyword(s):

Surface Layer ◽

Experimental Studies ◽

Calcium Content ◽

Degradation Process ◽

The Body ◽

Atmospheric Water ◽

A Value ◽

Architectural Monument ◽

Similarity Law ◽

Selection Of

This paper discusses the results of experimental studies on the selection of the repair mixture compound for recreating the surface layer of the historical brick of the 18th century architectural monument “Commercial Bank” in Arkhangelsk. According to the research results, it was found that the historical brick has a relatively higher density and increased calcium content than the modern one. The characteristics of the surfaces of the analyzed materials based on the component indicators of specific surface energy showed that the brick of 1859, characterized by the highest degree of destruction, has the maximum value of the polar energy component. This fact may indicate a greater hydrophilicity of the surface in relation to atmospheric water and, as a result, a more intensive degradation process. It is established that the composition of the repair mixture with the addition of brick crumbs in the amount of 50 % has a value of the polar part of the surface tension equal to similar parameters for historical bricks (1786 and 1859) after their preliminary priming. The use of this mixture to recreate the surface layer of the brick will allow atmospheric water to pass freely through the repair compound and the body of the brick, without concentrating on the interface and without causing its destruction and detachment when drying.

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Abundance of chewing lice (Phthiraptera: Amblycera and Ischnocera) increases with the body size of their host woodpeckers and sapsuckers (Aves: Piciformes: Picidae)

The Canadian Entomologist ◽

10.4039/tce.2017.18 ◽

2017 ◽

Vol 149 (4) ◽

pp. 473-481 ◽

Cited By ~ 6

Author(s):

Terry D. Galloway ◽

Robert J. Lamb

Keyword(s):

Body Size ◽

Body Mass ◽

Host Species ◽

The Body ◽

Louse Infestation ◽

Mean Intensity ◽

Chewing Lice ◽

Host Body ◽

Northern Flicker ◽

Host Body Mass

AbstractSpecimens of five species of woodpeckers (Piciformes: Picidae) from Manitoba, Canada, were weighed and examined for chewing lice, 1998–2015: downy woodpecker (Picoides pubescens (Linnaeus), n=49), hairy woodpecker (Picoides villosus (Linnaeus), n=23), pileated woodpecker (Dryocopus pileatus (Linnaeus), n=10), northern flicker (Colaptes auratus (Linnaeus), n=170), and yellow-bellied sapsucker (Sphyrapicus varius (Linnaeus), n=239). The relationship between body mass of each host species and infestation by seven species of lice was analysed: Menacanthus pici (Denny) from all host species, Brueelia straminea (Denny) from Picoides Lacépède species, Penenirmus jungens (Kellogg) from northern flicker, Penenirmus auritus (Scopoli) from the other four hosts, Picicola porisma Dalgleish from northern flicker, Picicola snodgrassi (Kellogg) from Picoides species, and Picicola marginatulus (Harrison) from pileated woodpeckers. Mean abundance of lice increased with the mean mass of their host. Neither the species richness of lice nor the prevalence of lice were related to host body mass. Host body mass explained 98% of the variation in mean intensity of louse infestation among hosts. The positive association of mean intensity and body size was also detected for three genera of lice. Louse intensity also increased with body size for individual birds, more so for some species of lice and hosts than others. Body size matters, but the adaptations that allow higher mean intensity on larger host species remain to be determined.

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The natural selection of metabolism and mass selects allometric transitions from prokaryotes to mammals

10.1101/084624 ◽

2016 ◽

Cited By ~ 2

Author(s):

Lars Witting

Keyword(s):

Natural Selection ◽

Body Mass ◽

Three Dimensional ◽

The Body ◽

Net Energy ◽

A Value ◽

Spatial Dimensions ◽

Self Replication ◽

Selection Of ◽

Evolution Proceeds

AbstractInter-specific body mass allometries can evolve from the natural selection of mass, with ±1/4 and ±3/4 exponents following from the geometry of intra-specific interactions when density dependent foraging occurs in two spatial dimensions (2D, Witting, 1995). The corresponding values for three dimensional interactions (3D) are ±1/6 and ±5/6.But the allometric exponents in mobile organisms are more diverse than the prediction. The exponent for mass specific metabolism tends to cluster around −1/4 and −1/6 in terrestrial and pelagic vertebrates, but it is strongly positive in prokaryotes with an apparent value around 5/6 (DeLong et al., 2010). And a value around zero has been reported in protozoa, and on the macro evolutionary scale from prokaryotes over larger unicells to multicellular vertebrates (Makarieva et al., 2005, 2008).I show that mass specific metabolism can be selected as the pace of the resource handling that generates net energy for self-replication and the selection of mass, and that this selection of metabolism and mass is sufficient to explain metabolic exponents that decline from 5/6 over zero to −1/6 in 3D, and from 3/4 over zero to −1/4 in 2D. The decline follows from a decline in the importance of mass specific metabolism for the selection of mass, and it suggestsi) that the body mass variation in prokaryotes is selected from primary variation in mass specific metabolism,ii) that the variation in multicellular animals are selected from primary variation in the handling and/or densities of the underlying resources,iii) that protozoa are selected as an intermediate lifeform between prokaryotes and multicellular animals, andiv) that macro evolution proceeds along an upper bound on mass specific metabolism.

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Behaviours in trematode cercariae that enhance parasite transmission: patterns and processes

Parasitology ◽

10.1017/s0031182000085048 ◽

1994 ◽

Vol 109 (S1) ◽

pp. S3-S13 ◽

Cited By ~ 120

Author(s):

C. Combes ◽

A. Fournier ◽

H. Moné ◽

A. Théron

Keyword(s):

Definitive Host ◽

External Environment ◽

Life Cycles ◽

Parasite Transmission ◽

Intermediate Hosts ◽

Larval Stages ◽

Active Life ◽

Host Life ◽

Patterns And Processes ◽

Almost All

Cercariae, like miracidia, are non-parasitic larval stages implicated in the life cycle of all trematodes for the host-to-host parasite transmission. Almost all cercariae are free-living in the external environment. With a few exceptions (cercariae of Halipegus occidualis (Halipegidae) can live several months, Shostak & Esch, 1990a), cercariae have a short active life during which they do not feed, living on accumulated reserves. Most cercariae encyst as metacercariae in second intermediate hosts which are prey of the definitive host; in certain species, the interruption of the active life is achieved by an encystment in the external environment (or a simple immobile waiting strategy in a few species). In some two-host life cycles, the cercariae develop into adults after penetration (this is the case for various species causing human schistosomiasis). Some cercariae do not leave the mollusc which must then be ingested by the definitive host.

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The Life Cycles of Dipetalonematid Nematodes (Filarioidea, Dipetalonematidae): The Problem of Their Evolution

Journal of Helminthology ◽

10.1017/s0022149x00004454 ◽

1957 ◽

Vol 31 (4) ◽

pp. 203-224 ◽

Cited By ~ 15

Author(s):

Roy C. Anderson

Keyword(s):

Life Cycle ◽

Skin Lesion ◽

Intermediate Host ◽

Definitive Host ◽

Life Cycles ◽

The Body ◽

Intermediate Hosts ◽

Cutaneous Lesions ◽

The Family ◽

Subcutaneous Tissues

The evolution of the life cycles of the members of the family Dipetalonematiidae Wehr, 1935 (Filarioidea) is considered in the light of existing knowledge of spirurid nematodes. The hypothesis that the life cycles of the dipetalonematids originated from life cycles similar to those of Draschia megastoma, Habronema muscae and H. microstoma is considered to be incorrect. Alternatively, it is pointed out that in the primitive subfamily Thelaziinae Baylis and Daubney, 1926 there are forms with typical spiruroid life cycles (Rhabdochona ovifilamenta), forms with life cycles approaching those of the dipetalonematids (Thelazia spp.), and forms with life cycles intermediate between these two (Oxyspirura spp.). It is suggested that intestinal species similar to Rhabdochona gave rise to the more specialized spiruroids and forms that left the gut (Oxyspirura, Thelazia) gave rise to the dipetalonematids.The dipetalonematids are believed to have originated from nematodes resembling the species of Thelazia and having life cycles like those of T. rhodesii, T. skrjabini and T. gulosa. Some of these worms established themselves in subcutaneous tissues. Like Parafilaria multipapillosa, they released their eggs through a break in the skin of the definitive host, thus causing a skin lesion that attracted various haematophagous arthropods which finally became involved as intermediate hosts in the life cycle. Certain species like the members of Parafilaria and Stephanofilaria (?) came to rely upon intermediate hosts that were unable to break the skin of the definitive host (Musca) and cutaneous lesions became permanent features of their life cycles. Other species became dependent upon intermediate hosts that could puncture the skin (mosquitoes, simuliids etc.) and skin lesions became unnecessary to the life cycle. The larvae of these worms then began to spread into the tissues of the skin, as found in Stephanofilaria, Onchocerca, and some species of Dipetalonema, and the infective larvae developed the ability to penetrate into the wound made by the intermediate host and perhaps, in some cases, the intact skin. Ultimately the larvae of some species habitually entered, or were deposited into, the blood stream and the adult worms were then free to colonize the vertebrate body as their larvae would then be available to the intermediate host no matter where the latter fed on the body of the definitive host; this group of worms gave rise to the many members of the family Dipetalonematidae.The family Filariidae Claus, 1883 is briefly reviewed in the light of the above hypothesis. It is pointed out that many species, e.g. Diplotriaeninae Skrjabin, 1916, live in the air sacs of reptiles and birds and probably have life cycles similar to that of Diplotriaenoides translucidus, i.e. the eggs pass through the lungs, up the trachea and out in the faeces. It is thought that these forms may represent a separate line of evolution from that which gave rise to the Dipetalonematidae. Certain genera (Lissonema, Aprocta), occurring in the orbits of birds, probably have life cycles like Thelazia or Oxyspirura. Many other genera occurring in superficial muscles and subcutaneous tissues (Squamofilaria, Ularofilaria, Tetracheilonema, Pelecitus, Monopetalonema) may release their eggs through some sort of skin lesion. Studies on these forms are urgently needed as the details of their life cycles may shed fresh light on the origins of the more specialized filarioids.

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Toxic effects of two commercial polybrominated diphenyl ethers on Artemia larvae at three developmental stages

Crustaceana ◽

10.1163/15685403-bja10042 ◽

2021 ◽

Vol 94 (2) ◽

pp. 177-187

Author(s):

Qingtian Zhang ◽

Sifan Guo ◽

Guikun Hu

Keyword(s):

Developmental Stage ◽

Polybrominated Diphenyl Ethers ◽

Developmental Stages ◽

Experimental Studies ◽

Mortality Rates ◽

The Body ◽

Toxic Effects ◽

Abnormal Behaviour ◽

Diphenyl Ethers ◽

Selection Of

Abstract Toxic effects of two commercial products, penta-BDE (DE-71) and octa-BDE (DE-79), on larvae of the brine shrimp, Artemia, were studied. Results showed that their toxic effects were related not only to the concentration and exposure time, but also to the developmental stage of Artemia. Newly hatched Artemia nauplii showed stronger tolerance than those at metanauplius stage or pseudoadult stage, while DE-71 showed a stronger toxic effect than DE-79 to some extent. Abnormal behaviour of Artemia larvae might occur within 12 h, and sometimes mortality rates increased quickly even if there was no death within 36 h. Both DE-71 and DE-79 showed significant influences on the body length of Artemia larvae within 24 h; the higher the concentration, the stronger the inhibition. As far as a toxic testing standard is concerned, further experimental studies on the selection of Artemia population and developmental stage are essential.

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The mismeasure of (obese) man – body mass index is an inadequate indicator of body condition

10.1101/149088 ◽

2017 ◽

Cited By ~ 1

Author(s):

Lukáš Kratochvíl ◽

Jaroslav Flegr

Keyword(s):

Body Mass Index ◽

Body Mass ◽

Body Condition ◽

Body Height ◽

Experimental Studies ◽

Epidemiological Studies ◽

The Body ◽

World Health ◽

Systematic Bias ◽

Health Organization

AbstractThe body mass index (BMI), recommended also by the World Health Organization, is currently used as the leading body condition indicator in clinical and epidemiological studies and has become popular among the general public. Here we provide evidence of a systematic bias in BMI, showing that BMI is dependent on body height. As a result, shorter persons have a greater chance of being classified as underweight, while taller persons as overweight, even if they have identical nutritional status. Use of BMI should be thus abandoned in diagnosis as well as in clinical and experimental studies.

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On the issue of choosing vertical and horizontal connections in a bogie for freight cars of high-speed trains

Vestnik of the Railway Research Institute ◽

10.21780/2223-9731-2020-79-6-351-359 ◽

2021 ◽

Vol 79 (6) ◽

pp. 351-359

Author(s):

G. I. Gadzhimetov ◽

G. I. Petrov ◽

Yu. A. Panin ◽

I. E. Il’in

Keyword(s):

High Speed ◽

Dynamic Properties ◽

Experimental Studies ◽

Development Program ◽

The Body ◽

Rolling Stock ◽

Spring Suspension ◽

Design Solutions ◽

Design Speed ◽

Selection Of

To increase the competitive advantages of rail freight transportation, the long-term development program of the Russian Railways provides for an increase in the speed of freight trains. The design speed of freight cars currently operating on the railway network is mainly 120 km/h, and the permitted speed is limited to 90 km/h. One of the possible solutions to the problem is the introduction of freight cars with an increased speed. At JSC “VNIIZHT” and JSC “VNIKTI”, work is being carried out on the selection of structures, the development of safety requirements, theoretical and experimental studies of freight traffic at increased speeds. In 2017—2018 at the Belorechenskaya—Maikop high-speed test range of the North Caucasian Railway, specialists of JSC “VNIIZHT” carried out running tests of a prototype of a platform car for transporting containers with a design speed of 160 km/h, developed by JSC “VNIKTI”. In the design of the platform car, a bogie is used, which is an analogue of the bogie of trailed cars of electric trains ED4 and ED9, with the selection of the stiffness of the springs in the spring suspension steps to comply with the difference in the level of the automatic coupler from the rail head in the “container” and “gross” modes. Analysis of the results of running tests allows determining the ways to improve the design of the bogie. To select design solutions for the purpose of ensuring safety, a review of the studies of domestic scientists aimed at studying the dynamic properties of railway rolling stock with various designs of the carriage part was carried out. Tests were carried out on prototypes of rolling stock having different elastic-dissipative connections in the “body-bogie-wheelsets” system. Based on the results of the analysis, design solutions have been determined that allow achieving satisfactory dynamic qualities for a freight car at a speed of up to 140 km/h. The adopted design solutions were tested on the basis of the results of theoretical studies of the dynamic properties of a platform car with a new bogie, carried out by the method of computer simulation. Increasing the flexibility of the spring suspension and the horizontal connection of the body with the bogie made it possible to improve the dynamic qualities of freight cars. To assess the safety during certification, it is required to develop a standard that would take into account the design features of car bogies, designed for increased speed.

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