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Biomedical subjects

P M Nollen

Publications and source records attributed to P M Nollen.

At least 19 recordsLinked to original sources
PubMed1992

Responses of Echinostoma caproni miracidia to gravity, light, and chemicals.

In a four-tube vertical system, Echinostoma caproni miracidia exhibited a strong negative geotaxis which was dominated by a positive phototaxis. In horizontal chambers a positive phototactic response was also demonstrated. These miracidia showed a positive chemoresponse, as determined in phi-chambers, to glutamic and aspartic acids but not leucine. Positive responses were also elicited to snail-conditioned water and sulfuric and acetic acids. Ammonia, Mg2+, and HCl produced no significant reactions. Responses of E. caproni and Schistosoma mansoni miracidia, both of which develop in Biomphalaria glabrata snails, were similar providing further evidence that miracidia mimic the behavioral patterns of compatible snail species.

Animals↗
PubMed1992

A comparison of the surface features of Philophthalmus megalurus and Philophthalmus gralli rediae by scanning electron microscopy.

General features observed on the surface of Philophthalmus megalurus and Philophthalmus gralli rediae include 2 rounded ambulatory buds, a tapered tail, a slitlike birth pore, and an oral opening surrounded by uniciliate sensory receptors. The tegument is folded in a ribbed pattern and is covered with small microvilli. The sensory receptors are concentrated on the lip of the oral opening but are less dense inside the buccal cavity. Both the birth pore and the buccal cavity are lined with a honeycomblike surface that may support the structural integrity of these highly extensible orifices. Major differences between the 2 species were noted in the structure of the sensory receptors. In P. megalurus they have flexible cilia that originate from a bulbous tegumental base. Receptors of P. gralli rediae are less dense, appear to have rigid cilia, and lack a bulbous base. In general P. megalurus rediae resemble more closely rediae of the philophthalmid Parorchis acanthus than they do those of P. gralli.

Animals↗
PubMed1991

A comparative study of the regenerative processes in a trematode, Philophthalmus gralli, and a planarian, Dugesia dorotocephala.

Adults of Philophthalmus gralli, an eyefluke of birds, were laterally amputated mid-way between the anterior testis and the ventral sucker. Worms were sampled at various short time intervals (30 min-6 h) after in vitro culture and long time intervals (1-8 days) after transplantation back to the host. Specimens were fixed for scanning electron microscopy and light microscopy and compared to the planarian, Dugesia dorotocephala, which was laterally transected in the pharyngeal region and maintained in springwater. It was found that wound closure took place by 2 days in the planaria; however, at the end of 8 days wound closure had been initiated but not yet completed in P. gralli. Replacement of major tissues was observed only in D. dorotocephala. Because calcium had been reported to be critical for planarian regeneration, a histochemical stain for calcium distribution was carried out. At the end of the 2-day study, no differences could be found in calcium distribution between the two organisms. No areas of calcium concentration were noted in any tissue important for the regenerative process.

Animals↗
PubMed1990

Escape of rediae from miracidia of Philophthalmus megalurus and Philophthalmus gralli during in vitro culture.

Miracidia of the eyeflukes Philophthalmus megalurus and Philophthalmus gralli contain a preformed larval stage that was identified as a redia by electron microscopy and, on living forms, by the presence of ambulatory buds and an oral opening. This redial stage escaped and actively moved about when the miracidium stopped swimming in pond water. No redial escape was observed in NaCl solutions even though miracidia became immobile, but escape was noted in Hanks' balanced salt solution (HBSS) after 7 hr of exposure. When miracidia were placed in RPMI-1640 and Eagle's minimum essential medium, rediae escaped much earlier than in pond water and HBSS. Redial escape in vitro will provide a good source of material to initiate cultures of this larval stage.

Animals↗
PubMed1990

Echinostoma caproni: mating behavior and the timing of development and movement of reproductive cells.

The development and movement of reproductive cells were determined in Echinsostoma caproni on autoradiograms by labeling nuclei of stem cells during exposure to [3H]thymidine and then transplanting the worms to mice for various times. The development and movement of sperm, primary oocytes, and vitelline cells were much more rapid in E. caproni than other digenetic trematodes investigated previously. Mating behavior was determined by labeling the sperm of 1 adult by in vitro exposure to [3H]tyrosine and transplanting alone or with unlabeled worms to mice for 4 and 6 days. Echinostoma caproni adults self-inseminated when isolated and self- and cross-inseminated when in groups. This behavior is similar to that found for the frog rectal fluke Megalodiscus temperatus but unlike that determined for eyeflukes in the genus Philophthalmus. Worm size was not a barrier to insemination in E. caproni. Cross-insemination could not be detected in 6-day transplants probably because of dilution or elimination of radioactive sperm due to rapid turnover or frequent sperm transfer. An increased number of structural anomalies was noted in the transplanted worms. The most common anomaly was an accumulation of vitelline cells in the vitelline reservoir and ducts.

Animals↗
PubMed1990

Chemosensitivity of Philophthalmus megalurus (Trematoda) miracidia.

Miracidia of the eyefluke Philophthalmus megalurus were tested in phi-chambers to determine if they reacted similarly to chemicals found stimulative for miracidia of Philophthalmus gralli, a closely related species. Philophthalmus megalurus miracidia were less responsive than P. gralli to the dicarboxylic amino acids and showed a significantly positive response only to 10 mM glutamic acid. These P. megalurus miracidia were chemonegative to 10 mM HCl and H2SO4, chemicals to which P. gralli miracidia gave a significantly positive response. Ammonia and Mg2+ did not elicit any response from P. megalurus miracidia.

Amino Acids↗
PubMed1989

Effects of concurrent infections on growth, development, distribution, and infectivity of adult Philophthalmus megalurus and Philophthalmus gralli.

Chickens were infected concurrently with 10 and 20 metacercariae/eye of Philophthalmus megalurus and Philophthalmus gralli. After 14 and 34 days of growth, the adults were removed and worm lengths, return rates, stage of development, and distribution within the host recorded. In a second experiment, chickens infected on day 1 with 10 metacercariae/eye of P. megalurus were concurrently infected with a similar dose of P. gralli on day 14. At day 34, the worms were removed and evaluated for the same parameters as in the first study. The effect of concurrent infections on worm length of P. gralli but not P. megalurus was significant when compared to single species control groups. In all cases recovery rates of P. megalurus in concurrent infections were significantly lower than controls, whereas P. gralli adults were recovered at lower rates only in 20-metacercariae--14-day infections. Maturation of eggs was delayed in both species in concurrent infections at the higher infection levels. Normal distribution was disrupted more for P. gralli at the higher infection levels and longer growth periods. Philophthalmus megalurus adults rarely left their normal habitat in the conjunctival sac. A delayed infective dose of P. gralli affected both species by disrupting normal distribution patterns, delaying egg development, and, in the case of P. megalurus, reducing the recovery rate. The possible role of crowding and antagonistic effects is discussed.

Animals↗
PubMed1979

Observations on spermatogenesis and inseminative behavior of Megalodiscus temperatus adults in frogs.

Upon in vitro exposure to 3H-adenosine, spermatogonial cells in adult Megalodiscus temperatus were readily labeled on autoradiograms. At least 20 days were required for these cells to produce labeled sperm, the longest time reported so far for digenetic trematodes. Labelled worms transplanted to hosts for 24--31 days showed both self- and cross-insemination in multiple infections. When alone, half of the transplanted adults self-inseminated.

Animals↗
PubMed1979

The longevity and hatchability of Philophthalmus megalurus and P. gralli miracidia in different environmental conditions.

The effects of salinity, pH, and temperature on the longevity and hatchability of miracidia of Philophthalmus megalurus and P. gralli were determined. Miracidia of both species are able to hatch and survive at saline concentrations much above physiological levels, although these processes are reduced in 2.0--2.4% saline and completely inhibited at 2.6%. The greatest hatching rates for both species were found near neutrality (pH 6--8) but some miracidia hatched at the extreme pH levels of 3 and 12. Philophthalmus megalurus miracidia exhibited longer half-lives under acid conditions (pH 2--6) than P. gralli miracidia; conversely, P. gralli miracidia showed longer half-lives in alkaline conditions (pH 8--11). Hatching and longevity were much greater below room temperature (5--20 C) than above (30--50 C) for miracidia of both species. Temperatures above 50 C proved lethal for eyefluke eggs. Except in acid pH, P. gralli miracidia showed longer half-lives than miracidia of P. megalurus. Comparison to studies on schistosomes revealed that the inhibitory effects of physiological saline and host body temperature on the hatching process of schistosome eggs does not occur in these 2 species of eyeflukes.

Animals↗
PubMed1979

The effects of miracidal aging and dilution of snail-conditioned water on responses of miracidia of Megalodiscus temperatus.

Miracidia of Megalodiscus temperatus from newly hatched until 10 hr old were tested for their ability to react to Helisoma trivolvis snail-conditioned water (SCW) by contact with return (CR) to agar blocks and by percentage of miracidia reacting to a point inoculation of SCW as determined by a photographic time exposure method. CR to agar blocks containing 1:50 SCW was greatest during the first 6 hr after hatching but declined thereafter. The reaction during the first hour to a point inoculation was lower than during the 2nd and 3rd hr. Results were variable from 4 to 10 hr after hatching with the lowest response recorded from 9 to 10 hr. Miracidial responses to dilutions of SCW were assessed by the same two methods. CR to agar blocks containing decreasing concentrations of SCW declined until at a dilution of 1:500 CR was only slightly above the controls. On the other hand, miracidial reactions to point inoculations of SCW as determined by the photographic method were still apparent at a dilution of 1:25,000, when 12% of the miracidia tested reacted. Thus, the photographic time exposure method gives a sensitive means for detecting altered miracidial behavior to various intrinsic and extrinsic factors.

Animals↗
PubMed1978

Studies on the reproductive system of Philophthalmus gralli using techniques of transplantation and autoradiography.

Adult Philophthalmus gralli exposed in vitro to 3H-thymidine for 6 hr showed label on autoradiograms over actively dividing cells in the testes, ovary, and vitellaria. In worms transplanted to chicks, oogonia became primary oocytes within 4 days and these were first found enclosed in newly formed eggs by 12 days. Tertiary spermatogonia at the periphery of the testes developed into sperm by 144 hr and were found in the serminal vesicle by 168 hr. Vitelline cells required 96 hr to travel from gland areas to become incorporated into eggs. In adults labeled in vitro for 1 hr with 3H-tyrosine and transplanted singly to chicks, only 2 of 28 self-inseminated. Labeled worms transplanted with unlabeled worms never self-inseminated but cross-inseminated with approximately 40% of the available worms. Transplanted worms localized in the chick's orbit in 3 microhabitats. In only 1 of 21 experiments did a labeled worm inseminate unlabeled worms outside of the microhabitat where it was found.

Animals↗
PubMed1978

Effects of stressful conditions on the development and movement of reproductive cells in Schistosoma japonicum.

Adult S. japonicum exposed to 3H-thymidine to label reproductive cells were cultured in vitro, maintained intraperitoneally, or transplanted as unisexual infections to hamsters. Daily samples were taken, processed for autoradiography, and observed for abnormal morphological and developmental characteristics. By day 5 of in vitro culture in Medium 199 and calf serum, all worms were dead. The vitelline system was the most sensitive to culture conditions and labeled vitelline cells never moved from the gland area. No labeled sperm were produced by males and evidence of deterioration of the testes was apparent by day 2. Degenerative changes of the ovary were the last to appear, on day 3. Most adults transplanted to the peritoneal cavity of hamsters were dead by day 3, but some lived for 6 days. No movement or development of reproductive cells was detected in these worms. An intense cellular reaction directed against the tegument was observed as early as day 1. Males transplanted in groups to the hepatic portal system were maintained normally in vivo and produced labeled sperm in 6 days. Females handled similarly showed degenerative changes in their genitalia by day 2, but most were alive after 6 days.

Animals↗
PubMed1977

Effects of stressful conditions on the development and movement of reproductive cells in Schistosoma mansoni.

Adult S. mansoni exposed to 3H-thymidine to label reproductive cells were cultured in vitro, maintained intraperitoneally, and transplanted to the hepatic portal vein of hamsters in unisexual infections. Daily samples were taken, processed for autoradiography, and observed for abnormal morphological and development characteristics. Males cultured in vitro did not produce labeled sperm and the testes exhibitied necrotic changes by the 5th day. Vitelline cell formation was normal for the first 5 days, but after that time both vitellaria and ovary showed degenerative changes. Males and females were still alive after 18 days of culture. Worms transferred to the peritoneal cavity were dead after 3 days, and no signs of reproductive development occurred during that time. Most males and a few females were encapsulated by cells thought to be of host origin. Males transplanted into hamsters in unisexual infections produced sperm in the normal time period and showed no morphological deterioration after 8 days. Females similarly handled were degenerating by day 3 and dead by day 6. Development and movement of reproductive cells was not detected in these females.

Animals↗
PubMed1977

Studies on growth, development, and infectivity of Philophthalmus hegeneri Penner and Fried 1963 in the chick.

A reinvestigation of the growth curve of Philophthalmus hegeneri in chicks showed rapid growth for the first 17 days after infection. After this, the growth rate declined for multiple infections (two or more worms per eye), and after 20 days, adults in monometacercarial infections ceased appreciable growth and never attained reproductive maturity. These results are similar to those reported by Fried (1962), but here adults were approximately 0.5 mm shorter in all cases and were slower in producing mature eggs. When worms from 28 to 36 days old from monometacercarial infections were transplanted into multiple infections, normal growth occurred. Worms recovered from multiple infections and transplanted singly grew normally for at least 18 days but recovery rates were extremely low. When P. hegeneri adults over 20 days old from monometacercarial infections were transplanted singly with Philophthalmus megalurus adults, growth was not stimulated in either species.

Animals↗
PubMed1976

The timing of reproductive cell development and movement in Schistosoma mansoni, S. japonicum, and S. haematobium, using techniques of autoradiography and transplantation.

Tritiated thymidine was incorporated into gonial and vitelline cells of male and female Schistosoma mansoni, S. japonicum, and S. haematobium after 2 hr of incubation. Spermatogonial cells developed into labeled mature sperm after 6 days of transplantation in all species. Insemination of females was detected on the same day indicating copulation is frequent. Oogonia labeled in the initial incubation matured into primary oocytes after 7 days of transplantation for S. mansoni and S. haematobium and after 6 days in S. japonicum. Cytoplasmic thymidine label was observed after 2-hr incubations in the primary oocytes of all species. Initial label in the vitellaria was scattered and heavy. After 3 days of transplantation, label was considerably diluted and by day 6 was undetectable in vitelline glands. These times for development and movement of reproductive cells are considered to be standards against which the effects of stressful conditions on the reproductive system can be assessed.

Animals↗