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PubMed1993

Identification and characterization of the proteolytic enzymes in the developmental stages of the eel-pathogenic nematode Anguillicola crassus.

The proteolytic activities of homogenates prepared from the second larva (L2) and the third larva (L3) as well as the adult stage of the eel-pathogenic nematode Anguillicola crassus were examined using hemoglobin, azocoll, elastin-orcein, and keratin azure as substrates. Whole bodies of L2 larvae, the anterior third of the bodies of L3 larvae, and the anterior fifth of the bodies of adults were studied. Extracts of L2 contained a trypsin-like proteinase exhibiting a molecular weight of 38,000 Da on gelatin-substrate gel electrophoresis. The proteinase showed a pH optimum at 8 and activity against azocoll and keratin. An apparent molecular weight of 25,000 Da was determined for the trypsin-like proteinase of the L3. This enzyme possessed collagenolytic, keratinolytic and slight elastinolytic activity at an optimal pH of 8. Samples of adults contained an aspartyl proteinase with a molecular weight of 90,000 Da. When hemoglobin was used as the substrate, the enzyme displayed optimal activity at pH 5. It was concluded that the proteinases of the larval stages are penetration enzymes, whereas that of the adult stage is a digestive enzyme.

Animals↗
PubMed1995

A pilot study on the efficacy of epiroprim against developmental stages of Toxoplasma gondii and Pneumocystis carinii in animal models.

The new bacteriocidal drug epiroprim (Ro-11-8958) was tested (alone or in combination with dapsone) on its efficacy against Toxoplasma gondii and Pneumocystis carinii in their hosts: laboratory mice and/or nude mice/rats, and was compared to the curative effects of the recent drugs of choice. The experiments clearly pointed out that epiroprim has significant effects on the reduction of both parasites when given alone. In combination with dapsone epiroprim led to a complete cure of toxoplasmosis in mice. This finding is of some importance for AIDS patients mostly suffering from bacteriosis and parasitosis at the same time.

Animals↗
PubMed1984

The effects of sym. Triazinones on developmental stages of Eimeria tenella, E. maxima and E. acervulina: a light and electron microscopical study.

The development of three chicken coccidia (Eimeria tenella, E. acervulina and E. maxima) was studied by means of light and electron microscopy. One group of chickens infected with 6000-20,000 oocysts received a single dose of 5 mg/kg body weight (comparable to approx. 25 ppm in the feed) Bay Vg 7183 or Bay Vi 9142 orally (on day 3 or 4 p.i.), whereas others received two doses (on days 3 and 4 or on days 4 and 5 p.i.). The animals were killed on days 3, 4, 5, 6 and 7 p.i. and parts of the mucosa were dissected from the caecum (E. tenella), the ileum (E. maxima) and the duodenum (E. acervulina). Significant damage was observed in comparison to the controls, affecting nearly all of the parasites in those animals that had been treated twice, whereas some of the parasites remained microscopically unchanged after only one treatment. In general, the perinuclear space, mitochondria and the endoplasmic reticulum were found to be considerably enlarged. Nuclear divisions were disturbed in schizonts and microgamonts, thus resulting in a greatly reduced production of parasites. The most important damage occurring in the macrogamonts concerned the wall-forming bodies II. As they burst, the formation of intact oocyst-walls was hindered, even if fertilization had taken place.

Animals↗
PubMed1991

Toxicity evaluation of Bayluscide and malathion to three developmental stages of freshwater snails.

Laboratory studies were conducted to assess the conditions under which the use of malathion in ricelands of Cameroon may impact the transmission of schistosomiasis. Helisoma trivolvis and Biomphalaria havanensis were selected as test organisms due to the lack of intermediate snail hosts in the U.S. Using Bayluscide as a reference molluscicidal compound, malathion was tested against snail eggs, juveniles, and adults. Snail eggs were more susceptible to Bayluscide and malathion than juvenile snails which in turn were more susceptible than adult snails. A Bayluscide concentration of 0.200 mg/L caused 100% mortality to adults of both snail species after 24 h exposure. This relatively high toxicity of Bayluscide to freshwater snails is one of the reasons why it has been recommended by the World Health Organization as the molluscicide of choice for control of schistosome-bearing snails. The concentrations of malathion resulting in 100% kill of adult snails after 24 h exposure were 1,200 mg/L for H. trivolvis and 500 mg/L for B. havanensis. After 48 h exposure, these concentrations were reduced to 500 mg/L and 300 mg/L, respectively. Therefore it is expected that the use of malathion for insect control in ricelands of Cameroon may affect the survival of freshwater snails including the intermediate hosts of bilharziasis.

Animals↗
PubMed1991

Toxicity evaluation of ammonium sulphate and urea to three developmental stages of freshwater snails.

Studies were performed to evaluate the toxic effects of ammonium sulphate and urea (chemical fertilizers currently applied in ricelands of Cameroon) against eggs, juveniles, and adults of two species of freshwater snails (Helisoma trivolvis and Biomphalaria havanensis). Results obtained from ammonium sulphate tests indicated 24-h LC50 values of 558 mg/L and 669 mg/L for eggs; 393 mg/L and 526 mg/L for juveniles, and 701 mg/L and 657 mg/L for adults of H. trivolvis and B. havanensis, respectively. Similar analysis with urea revealed LC50 values of 14,241 mg/L and 13,532 mg/L for eggs; 18,255 mg/L and 24,504 mg/L for juveniles and 30,060 mg/L and 26,024 mg/L for adults of H. trivolvis and B. havanensis, respectively. Following 48 h exposure, the concentrations of ammonium sulphate killing 100% of snails were 1,250 mg/L and 1,000 mg/L for the adults of H. trivolvis and of B. havanensis, respectively. Those of urea were computed to be 25,000 mg/L for H. trivolvis and 35,000 mg/L for B. havanensis. In rice culture in Cameroon, these fertilizers are applied at doses of 100 kg/ha (ammonium sulphate) and of 150 kg/ha (urea); hence, the above found concentrations lethal to snails appeared to be 10 to 13 times (ammonium sulphate) and to be 165 to 235 times (urea) higher assuming an average water depth of 10 cm in these ricefields. Therefore, the use of ammonium sulphate and urea as chemical fertilizers in ricelands of the Republic of Cameroon might adversely affect the survival of freshwater snails only in the case of spills or of stressful environmental conditions. Under normal laboratory conditions, both chemicals show a low molluscicidal activity with urea being about 25 to 35 times less potent than ammonium sulphate.

Ammonium Sulfate↗
PubMed1989

Development rates, fecundity and survival of developmental stages of the ticks Rhipicephalus appendiculatus, Boophilus decoloratus and B. microplus under field conditions in Zimbabwe.

To determine development rates, fecundity and survival of Rhipicephalus appendiculatus, Boophilus decoloratus and B. microplus, a study was carried out in long and short grass in the highveld of Zimbabwe. Engorged adult females of the three species and engorged larvae and nymphs of R. appendiculatus were buried beneath the soil in small cages in the rainy, cool and hot seasons in 1980 and 1981. Half the number of cages were examined regularly to determine development rates and half were left undisturbed to determine survival rates and the fecundity of engorged females. Development was most rapid during warm conditions and slowest during cool conditions, but high temperatures appeared to prolong the preoviposition periods of all species. The relationship between fluctuating temperatures and rate of development in the field was defined using a least-squares procedure. Survival of engorged females was usually high, but was reduced by predation when they were not protected. Fecundity was reduced in long grass during the cool season and in short grass during the hot season. A higher percentage of eggs hatched in the rainy season than in the cool or dry seasons. The survival of engorged larvae and nymphs was usually high in all seasons. Engorged nymphs were the hardiest stage and eggs the most suceptible stage to adverse microclimatic conditions.

Animals↗
PubMed1977

Changes in the thermal denaturation profiles of DNA from different developmental stages of the newt Triturus vulgaris.

The melting profiles of DNA samples from the early gastrula and early neurula of Triturus vulgaris are essentially the same, whereas DNA from mid to late gastrula possesses higher Tm values and shows a deviation from the regular sigmoidal shape at temperatures above Tm. The plot on normal probability paper indicates a second DNA fraction which melts at higher temperatures and, consequently, it has a higher GC-content than the bulk of DNA. These facts confirm our idea that differential DNA replication occurs during gastrulation.

Animals↗