Survival characteristics of the free-living cercarial population of the ectoparasitic digenean Transversotrema patialensis (Soparker, 1924)

Parasitology ◽  
1975 ◽  
Vol 70 (3) ◽  
pp. 295-310 ◽  
Author(s):  
R. M. Anderson ◽  
P. J. Whitfield
Keyword(s):  
Mathematical Models ◽  
Life Span ◽  
Conceptual Understanding ◽  
Biological Processes ◽  
Energy Reserves ◽  
Age Dependence ◽  
Maximum Life Span ◽  
Free Living ◽  
Age Dependent ◽  
Low Levels

The survival characteristics of free-living cercarial populations of Transversotrema patialensis were described and shown to be age-dependent. The maximum life-span was found to be 44 h with a 50% survival at 26 h. Activity and infectivity of the larvae were also characterized by age-dependence, and were demonstrated to be closely correlated with one another. For individual cercariae, both activity and infectivity had dropped to extremely low levels many hours before death occurred. An attempt was made to interrelate activity and infectivity, in a theoretical manner, with the availability of energy reserves.Conceptual understanding of the biological processes involved was aided by the formulation of simple mathematical models.

An experimental study of the survival characteristics, activity and energy reserves of the hexacanths of Hymenolepis diminuta

Parasitology ◽  
1975 ◽  
Vol 71 (1) ◽  
pp. 137-151 ◽  
Author(s):  
R. M. Anderson ◽  
R. C. Lethbridge
Keyword(s):  
Experimental Study ◽  
Survival Rate ◽  
Life Span ◽  
Close Correlation ◽  
Hymenolepis Diminuta ◽  
Energy Reserves ◽  
Maximum Life Span ◽  
Age Dependent ◽  
Quantitative Results ◽  
Similar Survival

Similar survival characteristics were demonstrated for hexacanths of Hymenolepis diminuta incubated in Tyrode's solution with or without a glucose supplement (0–50 mg/ml).The survival rate of hexacanths in all media tested was shown to be age-dependent and led to a maximum life-span of approximately 11 h.The amount of energy reserves, as measured by microdensitometric determinations of PAS + material, declined rapidly in time to a plateau at approximately 8 h. Residual PAS + matter present beyond that period was interpreted as structural and thus non-utilizable material.The rate of activity as measured by hook movements declined more rapidly, and continuous hook cycles were rarely observed after 2 h and ceased after 4 h. A close correlation was demonstrated between the decline in PAS + material and the total number of hook cycles completed per unit of time.The quantitative results on survival, energy reserves and activity are discussed in relation to the penetration of hexacanths into the haemocoele of the intermediate host.

Experimental studies on the transmission dynamics of the cercariae of Echinoparyphium recurvatum (Digenea: Echinostomatidae)

Parasitology ◽  
1983 ◽  
Vol 87 (1) ◽  
pp. 167-174 ◽  
Author(s):  
N. A. Evans ◽  
D. M. Gordon
Keyword(s):  
Life Span ◽  
Intermediate Host ◽  
Experimental Studies ◽  
Intermediate Hosts ◽  
Maximum Life Span ◽  
Age Dependent ◽  
Second Intermediate Host ◽  
The Mean ◽  
The Relationship ◽  
First Intermediate Host

SUMMARYAge-dependent survival and infectivity characteristics are described for the cercariae of Echinoparyphium recurvatum. At 18 °C the maximum life-span of the cercariae was 48 h and 50% survival occurred at 30·5 h. Infectivity of cercariae to the second intermediate host, Lymnaea peregra was maximal approximately 2 h after emission from the first intermediate host and it subsequently declined to zero at 19 h. It is suggested that the period of sub-maximal infectivity at the beginning of the cercarial life-span may represent a phase during which dispersal is an important function of the larvae. The relationship between infective stage density and establishment success was linear up to densities equivalent to 5000 cercariae/1. At higher cercarial densities the proportion of parasites establishing in second intermediate hosts declined progressively with increasing cercarial density. The mean number of parasites establishing/host increased linearly with increasing host size.

Survival and infectivity of Hypoderaeum conoideum and Euparyphium albuferensis cercariae under laboratory conditions

1999 ◽  
Vol 73 (2) ◽  
pp. 177-182 ◽  
Author(s):  
R. Toledo ◽  
C. Muñoz-Antoli ◽  
M. Pérez ◽  
J.G. Esteban
Keyword(s):  
Life Span ◽  
Natural Habitat ◽  
Energy Levels ◽  
Age Dependency ◽  
Maximum Life Span ◽  
Laboratory Conditions ◽  
Age Dependent ◽  
Infective Period

The survival characteristics of the cercariae of Hypoderaeumconoideum and Euparyphiumalbuferensis (Trematoda: Echinostomatidae) at 20°C and 30°C are described, and the age dependency of their infectivity at 20°C is studied to determine their respective transmission efficiencies. Cercarial survival was found to be age-dependent and was higher at 20°C. For both cercariae, the maximum life-span was 26 h at 20°C and 16 h at 30°C, and their respective times to 50% mortality were similar at each temperature. Both cercariae seem to be well adapted to transmission in their natural habitat, though cercarial infectivity of H. conoideum was higher than that of E. albuferensis, this being correlated with their prevalences in nature. The age-dependency of cercarial survival may be related to steadily diminishing endogenous energy levels, though the delay in attaining maximum infectivity suggests that other factors not related to energy considerations are involved in the delimitation of the cercarial infective period. However, this latter observation may constitute an adaptative mechanism allowing cercarial dissemination.

Methodology of Research in Micropollutants – Heavy Metals

1982 ◽  
Vol 14 (12) ◽  
pp. 107-125 ◽  
Author(s):  
Roland Wollast
Keyword(s):  
Heavy Metals ◽  
Mathematical Models ◽  
Aqueous Phase ◽  
Suspended Matter ◽  
Solid Phase ◽  
Aquatic Organisms ◽  
Biological Processes ◽  
Particulate Phase ◽  
Sources Of Pollution ◽  
Adsorption Desorption

A comparison of the concentration of dissolved and of particulate heavy metals in the aquatic system indicates that these elements are strongly enriched in the suspended matter. The transfer between the aqueous phase and the solid phase may be due to dissolution-precipitation reactions, adsorption-desorption processes or biological processes. When these processes are identified, it is further possible to develop mathematical models which describe the behaviour of these elements. The enrichment of heavy metals in the particulate phase suspended or deposited and in aquatic organisms constitutes a powerful tool in order to evaluate sources of pollution.

scholarly journals Age-dependent and radial sectional differences in the dynamic viscoelastic properties of bamboo culms and their possible relationship with the lignin structures

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Yoko Okahisa ◽  
Keisuke Kojiro ◽  
Hatsuki Ashiya ◽  
Takeru Tomita ◽  
Yuzo Furuta ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Viscoelastic Properties ◽  
Structural Variation ◽  
Thermal Softening ◽  
Peak Temperature ◽  
Outer Side ◽  
Phyllostachys Pubescens ◽  
Age Dependence ◽  
Age Dependent ◽  
S Peak

Abstract Age is an important factor that dictates bamboo’s mechanical properties. In Japan, bamboo plants aged 3–5 years are selected for use as materials because of their robustness and decorative or craft-friendly characteristics. In this study, the age-dependent and radial sectional differences in bamboo’s dynamic viscoelastic properties in relation to lignin structural variation, were evaluated. We used Phyllostachys pubescens samples at the current year and at 1.5, 3.5, 6.5, 9.5, 12.5, and 15.5 years of age. There was a clear age dependence in the peak temperature of tan δ and in the yield of thioacidolysis products derived from β-O-4 lignin structures. The highest peak temperature tan δ value was detected in 3.5-year-old bamboo, which contained the highest amount of the thioacidolysis products. Moreover, tan δ’s peak temperature was always higher on the outer side, and the ratio of S/G thioacidolysis products was always higher on the inner side of bamboo plants of all ages. These results suggest that changes in bamboo’s thermal softening properties from aging are caused by the maturation and degradation of lignin in bamboo.

scholarly journals Mitochondrial membrane peroxidizability index is inversely related to maximum life span in mammals

1998 ◽  
Vol 39 (10) ◽  
pp. 1989-1994 ◽  
Author(s):  
Reinald Pamplona ◽  
Manuel Portero-Otín ◽  
David Riba ◽  
Cristina Ruiz ◽  
Joan Prat ◽  
...  
Keyword(s):  
Life Span ◽  
Mitochondrial Membrane ◽  
Maximum Life Span ◽  
Peroxidizability Index

scholarly journals The serotonin transporter gene and female personality variation in a free-living passerine

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bert Thys ◽  
Andrea S. Grunst ◽  
Nicky Staes ◽  
Rianne Pinxten ◽  
Marcel Eens ◽  
...  
Keyword(s):  
Serotonin Transporter ◽  
Strong Support ◽  
Serotonin Transporter Gene ◽  
Female Aggression ◽  
Nucleotide Polymorphisms ◽  
Transporter Gene ◽  
Evolutionary Potential ◽  
Free Living ◽  
Age Related ◽  
Age Dependent

AbstractQuantifying variation in behaviour-related genes provides insight into the evolutionary potential of repeatable among-individual variation in behaviour (i.e. personality). Yet, individuals typically also plastically adjust their behaviour in response to environmental conditions and/or age, thereby complicating the detection of genotype–phenotype associations. Here, using a population of free-living great tits (Parus major), we assessed the association between single nucleotide polymorphisms (SNPs) in the serotonin transporter gene (SERT) and two repeatable behavioural traits, i.e. female-female aggression and female hissing behaviour. For female-female aggression, a trait showing age-related plasticity, we found no evidence for associations with SERT SNPs, even when assessing potential age-dependent effects of SERT genotype on aggression. We also found no strong support for associations between SERT SNPs and hissing behaviour, yet we identified two synonymous polymorphisms (exon 13 SNP66 and exon 12 SNP144) of particular interest, each explaining about 1.3% of the total variation in hissing behaviour. Overall, our results contribute to the general understanding of the biological underpinning of complex behavioural traits and will facilitate further (meta-analytic) research on behaviour-related genes. Moreover, we emphasize that future molecular genetic studies should consider age-dependent genotype–phenotype associations for behavioural trait (co)variation, as this will vastly improve our understanding of the proximate causes and ultimate consequences of personality variation in natural populations.

Inter-annual repeatability and age-dependent changes in plasma testosterone levels in a longitudinally monitored free-living passerine bird

Oecologia ◽  
2021 ◽  
Author(s):  
Martin Těšický ◽  
Tereza Krajzingrová ◽  
Jiří Eliáš ◽  
Hana Velová ◽  
Jana Svobodová ◽  
...  
Keyword(s):  
Passerine Bird ◽  
Plasma Testosterone ◽  
Free Living ◽  
Testosterone Levels ◽  
Age Dependent

Life span bias explains live–dead discordance in abundance of two common bivalves

Paleobiology ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 783-797 ◽  
Author(s):  
Kelly E. Cronin ◽  
Gregory P. Dietl ◽  
Patricia H. Kelley ◽  
Stewart M. Edie
Keyword(s):  
North Carolina ◽  
Life Span ◽  
Field Study ◽  
Species Abundance ◽  
Mercenaria Mercenaria ◽  
Mortality Rates ◽  
Global Maximum ◽  
Bivalve Species ◽  
Maximum Life Span ◽  
Death Assemblages

AbstractLife span bias potentially alters species abundance in death assemblages through the overrepresentation of short-lived organisms compared with their long-lived counterparts. Although previous work found that life span bias did not contribute significantly to live–dead discordance in bivalve assemblages, life span bias better explained discordance in two groups: longer-lived bivalve species and species with known life spans. More studies using local, rather than global, species-wide life spans and mortality rates would help to determine the prevalence of life span bias, especially for long-lived species with known life spans. Here, we conducted a field study at two sites in North Carolina to assess potential life span bias between Mercenaria mercenaria and Chione elevata, two long-lived bivalve species that can be aged directly. We compared the ability of directly measured local life spans with that of regional and global life spans to predict live–dead discordance between these two species. The shorter-lived species (C. elevata) was overrepresented in the death assemblage compared with its live abundance, and local life span data largely predicted the amount of live–dead discordance; local life spans predicted 43% to 88% of discordance. Furthermore, the global maximum life span for M. mercenaria resulted in substantial overpredictions of discordance (1.4 to 1.6 times the observed live–dead discordance). The results of this study suggest that life span bias should be considered as a factor affecting proportional abundances of species in death assemblages and that using life span estimates appropriate to the study locality improves predictions of discordance based on life span compared with using global life span estimates.

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