Some influences of population density on Hymenolepis diminuta in rats

Parasitology ◽  
1975 ◽  
Vol 71 (3) ◽  
pp. 517-523 ◽  
Author(s):  
Carl Aage Hesselberg ◽  
Jørn Andreassen
Keyword(s):  
Population Density ◽  
Egg Production ◽  
Dry Weight ◽  
Hymenolepis Diminuta ◽  
Wet Weight ◽  
The Mean ◽  
Lower Recovery

When measured 56 days postinfection the length, wet weight and dry-weight of Hymenolepis diminuta were all found to decrease with increasing number of cysticercoids given up to 20. The mean position of the worms in 10, 12 and 20 worm infections is significantly posterior to that of 1, 2 and 5 worm infections and the worms are attached over a wider area of the intestine.Egg production by the worms was followed up to day 56 postinfection; the number of eggs produced per worm and even per rat decreased with increasing population density. Thus the best way to get most eggs and to maintain the parasite in the laboratory is to have rats infected with only one tapeworm.Rats given 1–20 cysticercoids showed a mean recovery of 100–65%, while rats given 40–200 cysticercoids showed a mean recovery ranging from 13 to 2%. In addition to ‘normal’ worms, defined as worms > 10 mm, small, most probably destrobilated, worms were found. In the 50 and 100 cysticercoid infections, worm recoveries were, respectively, 8% ‘normal’, 16% small, and 2% ‘normal’, 5% small. From the significantly lower recovery from heavy infections it is concluded that a deleterious factor is operating during the 8 weeks after the infection.

Differences in biological characteristics of two strains of the cestode Hymenolepis diminuta

Parasitology ◽  
1987 ◽  
Vol 95 (1) ◽  
pp. 97-110 ◽  
Author(s):  
H. Kino ◽  
C. R. Kennedy
Keyword(s):  
Egg Production ◽  
Genetic Basis ◽  
Strain Difference ◽  
Rattus Rattus ◽  
Dry Weight ◽  
Biological Characteristics ◽  
Hymenolepis Diminuta ◽  
Multiple Infections ◽  
The Mean ◽  
The Difference

SUMMARYBiological characteristics of infectivity, growth rate and fecundity of Hymenolepis diminuta isolated from wild Rattus rattus in Japan were compared with parasites of Texas origin maintained for several generations in this and many other laboratories in laboratory bred Rattus norvegicus. The timing of development and maturation was similar in parasites from both sources, but the mean parasite dry weight was less and the mean egg production lower in Japanese parasites in both single and multiple infections. The differences persisted over 10 weeks in single infections, and were unaffected by rat strain. In all experiments there was much greater variation and heterogeneity in the biological characteristics of the Japanese parasites. It was concluded that the Texas parasites were better adapted to R. norvegicus and in the course of adaptation had become more homogeneous, and that the difference between the parasite strains had a complex genetic basis. Some Japanese parasites of the early isolated generations failed to produce normal eggs, but the proportion of these decreased in later generations. However, selected individual Japanese parasites whose egg production was equal to that of parasites of Texas origin did not produce offspring of larger mean size or higher mean fecundity, and heterogeneity of these characteristics was maintained. In the intermediate host, the mean number of cysticercoids of the Japanese isolate per beetle was higher than that of the Texas strain in Tribolium confusum but lower in Tenebrio molitor. The greater heterogeneity exhibited by Japanese parasites and the genetic basis of the strain difference are discussed with particular reference to geographical isolation, differences in definitive hosts and co-evolution of wild and laboratory host and parasite populations.

THE EFFECT OF INGESTED CHLORTETRACYCLINE ON SOME HYDROLASES AND ORGANS ASSOCIATED WITH THE DIGESTIVE PROCESS IN GROWING PIGS: II. PROTEASE, AMYLASE, AND GELLULASE ACTIVITY OF THE CONTENTS OF THE SMALL INTESTINE AND OF THE CECUM; WEIGHTS OF SMALL INTESTINE AND MUCOSA

1957 ◽  
Vol 35 (3) ◽  
pp. 195-202 ◽  
Author(s):  
M. A. A. Vonk ◽  
L. W. McElroy ◽  
R. T. Berg
Keyword(s):  
Small Intestine ◽  
Dry Matter ◽  
Cellulase Activity ◽  
Dry Weight ◽  
Growing Pigs ◽  
Weanling Pigs ◽  
Intestinal Contents ◽  
Wet Weight ◽  
The Mean ◽  
Ad Libitum

Four treatments, involving differences in method of feeding and interval between last feed and slaughter, were employed in a study of the effect of dietary chlortetracycline on protease, amylase, and cellulase activity in the intestinal and cecal contents of 16 pairs of weanling pigs. Most consistent results were obtained with six pairs which were limited pair-fed except for the final feeding during which feed was available ad libitum for a 4-hour period ending 18 hours before slaughter. The mean total activities of all three hydrolases in the contents of the small intestines and of the ceca of the antibiotic-fed animals of these six pairs were significantly greater than in those of the control animals. Expressed as activity per gram dry matter of intestinal contents, significantly higher values for protease and amylase, but not for cellulase, were observed in the pigs that had received chlortetracycline. When the combined results obtained from all 16 pairs of the experimental animals were analyzed, the results showed that on a basis of activity per gram dry matter of intestinal contents, ingested chlortetracycline was associated with significant increases in amylase and cellulase but not in protease activity. Protease, amylase, and cellulase activities per gram dry matter of cecal contents were higher for pigs fed the antibiotic than for their controls. The mean wet weight of the empty small intestine and the mean dry weight of the mucosa scraped from the anterior 3-meter section of the small intestine were lower for the chlortetracycline-fed animals, but the differences were not statistically significant.

Population dynamics and production of a brine shrimp, Parartemia zietziana Sayce (Crustacea : Anostraca), in two salt lakes in westren Victoria, Australia

1977 ◽  
Vol 28 (4) ◽  
pp. 417 ◽  
Author(s):  
R Marchant ◽  
WD Williams
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Temperature Stress ◽  
Brine Shrimp ◽  
Dry Weight ◽  
Salt Lakes ◽  
Confidence Limits ◽  
Length Frequency ◽  
Population Densities ◽  
The Mean

Quantitative samples of P. zietziana were taken monthly for two years from Pink Lake and Lake Cundare. Shrimps were usually contagiously distributed. To reduce error, samples were stratified resulting in confidence limits of 40-50% for the mean population density. Despite this variability, stable trends emerged, and variation was not so great as to mask significant differences. Length-frequency analyses distinguished cohorts; a regression was established between length and dry weight, enabling growth to be estimated from samples. By combining growth with population densities in Allen curves, production was computed. In Pink Lake and Lake Cundare mean pro- duction was 11.3 and 1.0 g dry weight m-2 year-1 respectively. Generally there were two or three generations per year, but time and extent of recruitment were not predictable. Each generation suffered continuous mortality, the death of young shrimps accounting for most of the production. This mortality remains unexplained; there are no significant predators and salinity and temperature stress would occur only during summer.

Host age and the growth and fecundity of Hymenolepis diminuta in the rat

1988 ◽  
Vol 62 (2) ◽  
pp. 158-162 ◽  
Author(s):  
R. J. Quinnell
Keyword(s):  
Egg Production ◽  
Wistar Rats ◽  
Dry Weight ◽  
Hymenolepis Diminuta ◽  
Crowding Effect ◽  
Age Classes ◽  
Immunological Mechanisms ◽  
Worm Recovery ◽  
Male Wistar Rats ◽  
Old Rats

ABSTRACTFive, 20, and 80 cysticercoid infections of Hymenolepis diminuta were established in 1-, 2- and 5-month-old male Wistar rats. Worm numbers, dry weights and egg outputs were determined on day 28 post infection. Worm recovery was found to be independent of cysticercoid dose in 1-month-old rats, but density-dependent in older rats. Density dependence affected both worm dry weight and egg production in all 3 age classes of host studied. However, at the highest dose both dry weight and egg production were significantly decreased in 2- and 5-month-old rats compared with 1-month-old rats. The results cannot be explained solely in terms of competition for a resource, and suggest that immunological mechanisms may have an important role in the “crowding effect”.

scholarly journals The effect of iron supplements on pregnancy in rats given a low-zinc diet

1984 ◽  
Vol 52 (1) ◽  
pp. 79-86 ◽  
Author(s):  
Susan J. Fairweather-Talt ◽  
Viv Payne ◽  
Christine M. Willians
Keyword(s):  
Fetal Growth ◽  
Normal Level ◽  
Dna Content ◽  
Wistar Rats ◽  
Dry Weight ◽  
Iron Supplements ◽  
Zn Concentration ◽  
Female Wistar Rats ◽  
Wet Weight ◽  
The Mean

1. Female Wistar rats were given an adequate-zinc (60 μg/g) or low-Zn (7 μg/g) diet for a minimum of 2 weeks and then mated. They were then either continued on the same diets (+Zn –Fe or –Zn –Fe) or given similar diets supplemented with four times the normal level of iron (+Zn + Fe or –Zn + Fe). The day before parturition they were killed and the fetuses removed and analysed.2. There were no differences in numbers of fetuses or the number of resorption sites. In the absence of Fe supplementation, the mean fetal wet weight was significantly less (P < 0.05) in the low-Zn group but there was no effect of Zn in the two Fe-supplemented groups. The addition of Fe significantly decreased (P < 0.05) the mean fetal wet weight in the adequate-Zn groups but had no effect in the low-Zn groups. There were no differences in fetal dry weight, fat, protein or DNA content. Both Fe-supplemented groups produced fetuses of higher Fe concentration (P < 0.01), and mothers with higher bone Fe-concentration (P < 0.01) compared with the non-supplemented groups. The low-Zn groups produced fetuses of lower Zn concentration (P < 0,001) than the adequate-Zn groups but there was no effect on maternal bone Zn concentration.3. It was concluded that Fe-supplements did not adversely affect fetal growth from mothers given a low-Zn diet, but the addition of Zn to the unsupplemented diet increased fetal wet weight. These findings were not accompanied by any other differences in fetal composition or dry weight, and do not therefore lend support to the suggestion of an Fe-Zn interaction.

scholarly journals Progress towards clover cyst nematode resistant white clover

1996 ◽  
pp. 237-241
Author(s):  
J. Van den Bosch ◽  
C.F. Mercer
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Egg Production ◽  
First Generation ◽  
Control Method ◽  
Dry Weight ◽  
Mean Value ◽  
Cyst Nematode ◽  
Wide Range ◽  
The Mean

Clover cyst nematode (Heterodera trifolii) reduces growth and nutrient uptake of white clover (Trifolium repens) in New Zealand, and breeding resistant cultivars is the preferred control method for ecological and economic reasons. Resistant and susceptible selections were taken from a wide range of white clover seedlines. Selected plants were intercrossed and reselected over two cycles of selection. Cysts per gram of root dry weight (cysts/ g) was the measure of resistance used, with low cysts/g plants being more resistant. The mean cysts/ g value of the progenies from resistant parents was 69% of the mean value of the progenies from susceptible parents in the first generation, and 38% in the second generation. Root weights were similar, while the resistant selections had 58% and 34% (first and second generations respectively) of the number of cysts in the susceptible selections. There were no immune plants (0 cysts) in the first generation and only two in the second. Counts were made of cysts, eggs per cyst and eggs per plant on clones of two resistant and two susceptible genotypes. The resistant genotypes had lower counts than the susceptible genotypes in terms of cysts per plant (means of 6 cf. 108), eggs per cyst (11 cf. 21) and eggs per plant (35 cf. 1650). The differences in numbers of cysts between resistant and susceptible lines increased during two generations of selection, supporting earlier results that indicated that progress in breeding for resistance was possible. Furthermore, the resistance is also acting on clover cyst nematode egg production which would further reduce recruitment to later generations of clover cyst nematode. Keywords: breeding, Heterodera trifolii, resistance, screening, selection, Trifolium repens

The effect of metacestodes of Hymenolepis diminuta on the bean-shaped accessory glands in male Tenebrio molitor

Parasitology ◽  
1998 ◽  
Vol 116 (2) ◽  
pp. 191-196 ◽  
Author(s):  
F. J. CARVER ◽  
H. HURD
Keyword(s):  
Endocrine System ◽  
Dry Weight ◽  
Total Activity ◽  
Tenebrio Molitor ◽  
Male Reproduction ◽  
Hymenolepis Diminuta ◽  
Total Protein Content ◽  
Molecular Weight Range ◽  
Accessory Glands ◽  
Wet Weight

Metacestodes of Hymenolepis diminuta affect several aspects of female reproductive physiology in Tenebrio molitor and such effects are mediated via the endocrine system. The effects on male reproduction are less well known and were studied with respect to the Bean-Shaped Accessory Glands (BAGs). The size and wet and dry weight of BAGs from infected and uninfected beetles were compared and rose to a plateau from 0–6 days post-emergence in uninfected beetles but in infected individuals continued to increase in both size and weight. These effects were density independent. Glands from both infected and uninfected beetles were assayed for trehalase activity measured by its ability to convert the sugar trehalose to glucose. The activity of this enzyme, per mg wet weight, was not affected by the parasite. However, total activity per gland increased in infected males. Total protein content and electrophoretic profiles of BAGs from infected and uninfected individuals showed no change in profile but showed an increase in all protein subunits per gland over a broad molecular weight range.

scholarly journals Area, depth and elevation of cryoconite holes in the Arctic do not influence Tardigrada densities

2016 ◽  
Vol 37 (2) ◽  
pp. 325-334 ◽  
Author(s):  
Krzysztof Zawierucha ◽  
Tobias R. Vonnahme ◽  
Miloslav Devetter ◽  
Małgorzata Kolicka ◽  
Marta Ostrowska ◽  
...  
Keyword(s):  
Dry Weight ◽  
The Arctic ◽  
Glacier Surface ◽  
Independent Variables ◽  
Rapid Melting ◽  
Sediment Mixing ◽  
The World ◽  
Wet Weight ◽  
The Mean ◽  
Water Bears

Abstract Water bears (Tardigrada) are known as one of the most extremophile animals in the world. They inhabit environments from the deepest parts of the oceans up to the highest mountains. One of the most extreme and still poorly studied habitats which tardigrades inhabit are cryoconite holes. We analysed the relation between area, depth, elevation and tardigrades densities in cryoconite holes on four glaciers on Spitsbergen. The mean (±SD) of cryoconite area was 1287.21±2400.8 cm2, while the depth was on average 10.8±11.2 cm, the elevation 172.6±109.66 m a.s.l., and tardigrade density 24.9±33.0 individuals per gram of wet material (n = 38). The densities of tardigrades on Hans Glacier reached values of up to 168 ind. cm3, 104 ind. g−1 wet weight, and 275 ind. g−1 dry weight. The densities of tardigrades of the three glaciers in Billefjorden were up to 82 ind. cm2, 326 ind. g−1 wet weight and 624 ind. g−1 dry weight. Surprisingly, although the model included area, depth and elevation as independent variables, it cannot explain Tardigrada density in cryoconite holes. We propose that due to the rapid melting of the glacier surface in the Arctic, the constant flushing of cryoconite sediments, and inter-hole water-sediment mixing, the functioning of these ecosystems is disrupted. We conclude that cryoconite holes are dynamic ecosystems for microinvertebrates in the Arctic.

scholarly journals Numbers and biomass of soil invertebrates in a reserved field in central Finland

1979 ◽  
Vol 51 (1) ◽  
pp. 172-187 ◽  
Author(s):  
Timo Törmälä
Keyword(s):  
Soil Surface ◽  
Dry Weight ◽  
Soil Invertebrates ◽  
Soil Invertebrate ◽  
Total Biomass ◽  
Invertebrate Community ◽  
Wet Weight ◽  
The Mean ◽  
Individual Size ◽  
Diptera Larvae

The numbers and biomasses of soil invertebrates were investigated in a reserved field in central Finland. Samples were taken monthly from June to September. Five methods were employed to extract the animals from the soil samples. The animals were counted, measured and their dry biomasses were estimated by body length/weight regressions and dry weight/wet weight ratios derived from the literature. In July the total biomass of the soil invertebrate community (excluding Protozoa, Tardigrada and Rotatoria) was about 9.6 g dry weight m-2. The most dominant groups were Lumricidae (73.1 %), Enchytraeidae (5,7 %), Oribatei (5.0 %), and Nematoda (4.4 %). In September the biomass of Diptera larvae was high (1.0 g dw m-2). In numbers nematodes were superior (maximum 12 million m-2) to other groups. Oribatei, Mesostigmata and Collembola were more concentrated to the soil surface than other Acari, Enchytraeidae and Nematoda. The mean individual size decreased with depth in all of the studied groups.

scholarly journals Heavy Metals in Muscle Tissue of Pterois volitans from the Veracruz Reef System National Park, Mexico

2019 ◽  
Vol 16 (23) ◽  
pp. 4611 ◽  
Author(s):  
Montoya-Mendoza ◽  
Alarcón-Reyes ◽  
Castañeda-Chávez ◽  
Lango-Reynoso ◽  
Zamudio-Alemán
Keyword(s):  
National Park ◽  
Microwave Digestion ◽  
Dry Weight ◽  
Atomic Absorption Spectrophotometry ◽  
National Standard ◽  
Pterois Volitans ◽  
Reef System ◽  
Wet Weight ◽  
The Mean ◽  
Mean Concentration

Concentrations of cadmium (Cd), lead (Pb), vanadium (V), and zinc (Zn) were measured in the muscle of 30 specimens of Pterois volitans, captured on April 2018, in the Veracruz Reef System National Park (VRSNP), Veracruz, Mexico. Concentrations, in the samples, were quantified with atomic absorption spectrophotometry (AAS), after microwave digestion. Results of the mean concentration, in descending order were V = 7.3 ± 0.7; Pb = 0.66 ± 0.07; Zn = 0.43 ± 0.14; and Cd = 0.03 ± 0.01 mg kg−¹ dry weight. These values did not exceeded limits established in the Mexican National Standard (NOM-242-SSA1-2009), of Cd and Pb (0.5 mg kg–¹) wet weight. This means that consumption of lionfish from this site does not pose a potential risk for human health.

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