bluuebunny/crossref_metadata_2025_split huggingface dataset:
Schistosoma mansoni: the sustentacular cells of the testes
Authors: Otubanjo O. A. 
Published: June 2009

SUMMARYStudies on the multiple compact testes of Schistosoma mansoni have revealed 2 principal cell types: germinal and non-germinal cells. Two morphological forms representing different stages in the cytomorphosis of the sustentacular cells have been considered. The polymorphic sustentacular cells which are conspicuously stained with potassium permanganate contain abundant ribosomal endoplasmic reticulum, glycogen particles and ribosomal masses in comparison with the germinal component of the testes. Golgi complexes with associated secretory bodies and vacuoles are present in the cells. The cytoplasm of the sustentacular cells interdigitate between other cells in the testes. Based on their morphology, nutritive, supportive and phagocytic functions have been attributed to the sustentacular cells. The possible recycling of nutrients by the cells is discussed. It is suggested that the cells regulate the production of spermatozoa from a nutritive viewpoint and also that the translocation of nutrients from the parenchyma to the testes is facilitated by these cells whose cytoplasm extends directly adjacent to the basal lamina.
An endogenous circadian hatching rhythm in the monogenean skin parasiteEntobdella soleae, and its relationship to the activity rhythm of the host (Solea solea)
Authors: Kearn G. C. 
Published: June 2009

When the eggs of the skin parasitic monogeneanEntobdella soleaeare subjected in the laboratory to alternating periods of light and darkness (LD 12:12, LD 6:18 or LD 18:6) at constant temperature (selected from the range 12–16 °C), hatching is rhythmical, most of the oncomiracidia emerging during the first 4 h of the period of illumination on each successive day.Rhythmicity in response to alternating 12 h periods of light and darkness persists in a wide range of lighting conditions including natural daylight and in dim blue light, the latter being similar in intensity (65 nW/cm2) and in spectral quality to light at the depths where the hostSolea solealives.The hatching rhythm persists with a periodicity of about 24 h in constant darkness and in constant light, provided that the eggs have been exposed previously to LD 12:12 until hatching begins. This indicates that there is a strong endogenous component to the rhythm.Eggs laid and maintained in total darkness develop and hatch, but the oncomiracidia may emerge at any time during each 24 h period and there is little evidence of rhythmicity.When alternate 12 h periods of light and darkness are reversed after the commencement of hatching, the hatching pattern also reverses after 24 h, so that emergence of larvae occurs at the beginning of the new illumination period.Mechanical disturbance plays little or no part as a hatching stimulus.Larvae, which had emerged from their eggs at some time between 20 and 80 min previously, responded to host skin, suggesting that an initial uninfective period is of short duration or absent.Hatching soon after dawn may have high survival value forE. soleaein view of the host's activity pattern; soles are active at night and partly bury themselves in the sediment (where the eggs of the parasite lie) at dawn, and the fish is inactive and a stationary target during the day.
The effect of parasitism by the trematode Cryptocotyle lingua (Creplin) on digestive efficiency in the snail host, Littorina saxatilis (Olivi)
Authors: Davis D. S. , Farley J. 
Published: June 2009

The efficiency of assimilation of carbon and nitrogen by Littorina saxatilis, as calculated from the carbon and nitrogen content of food and faeces, showed that the efficiency of snails infected with rediae of Cryptocotyle lingua did not differ significantly from that in non-infected snails.Similarly, the rate of ingestion and the rate of assimilation of infected snails did not differ significantly from those of non-infected snails.It is suggested that this harmonious relationship reflects the longterm strategy of Cryptocotyle lingua infections.
Immunity toPlasmodium bergheiin rats: maximum levels of protective antibody activity are associated with eradication of the infection
Authors: Phillips R. S. , Jones Valerie E. 
Published: June 2009

Maximum levels of protective antibody activity were reached in the circulation of rats given a primary infection or one or two re-infections ofPlasmodium bergheiat the time the infection was finally eradicated. This association of maximum protective antibody activity with complete clearance of the parasite was also found in recipients of lymphoid cells from immune donor rats and suggests that a high level of protective antibody activity is one essential factor in complete elimination of the parasite.Excellent technical assistance was given at different times by Mrs J. Page, Mr A. J. Edwards and Miss D. Leader.
The extraction, characterization andin vitrotranslation of RNA from adultSchistosoma mansoni
Authors: Tenniswood M. P. R. , Simpson A. J. G. 
Published: June 2009

SUMMARYWe have extracted RNA fromSchistosoma mansoniusing the lithium chloride–urea method which gives good yields of undegraded RNA. The results of agarose gel electrophoresis of RNA extracted by this procedure suggest thatS. mansonihas anin vivonick in the large rRNA sub-unit. Translation of the RNA in a rabbit reticulocyte lysate gave significant incorporation of [35S]methionine into synthesized proteins. Immuno-precipitation of these translation products using a hyperimmune monkey serum sedimented between 5 and 8% of the radioactivity, which appeared to be present in approximately 13 proteins of molecular weights 18, 20, 21, 22, 23, 35, 40, 54, 60, 70, 74, 78 and 105 K Daltons.
Schistosoma mansoni: quantification of skin penetration and early migration by differential external radioassay and autoradiography
Authors: Georgi Jay R. 
Published: June 2009

SUMMARYEleven gamma-emitting radionuclides (49Sc, 54Mn, 59Fe ( + 2 and + 3), 60Co, 65Zn, 75Se (as selenomethionine, selenocystine, selenite and selenate), 109Cd, 125Sb, 133Ba, 137Cs and 203Hg) were screened as labelling agents for Schistosoma mansoni cercariae by incubation of infected Biomphalaria glabrata snails in radioactive solution according to the technique of Christensen (1977). Only [75Se]methionine yielded satisfactorily labelled cercariae. Multiple regression analysis of volume, number of cercariae and radioactivity from a series of 10 aliquots of unwashed cercarial suspensions yielded estimates of unbound and cercarial-bound radioactivity that were equivalent or superior to estimates based on assay of washed cercariae and eliminated loss of cercariae. Washing of cercarial suspensions over 8 μm pore diameter Millipore filters was found to result in entanglement of 60–90% of the cercariae on the filter disc. Differential external radioassay, a new technique employing partial body shielding within a total body counter, permitted separate estimation of tail and body radioactivity of conscious mice previously exposed by tail immersion to 75Se-labelled cercariae, with measurements repeated as often as desired. Approximately 39% of the 75Se present in emergent cercariae was retained by schistosomula transformed in vitro but this was subject to considerable variation, especially in schistosomula transformed in vivo. Secreted or catabolized label from penetrant cercariae and schistosomula was rapidly removed from the skin by the bloodstream. Numbers of schistosomula in tail skin were directly proportional to the number of reduced silver foci counted on tail autoradiograms; only a very small fraction of tail radioactivity represented unbound (‘spurious’) label. Migration of schistosomula away from skin was 50% complete at 3·8–4·3 days, as determined by probit analysis of autoradiographic data.
Comparative migration, growth and development of Typhlocoelum cucumerinum sisowi in dabbling ducks and Typhlocoelum cucumerinum cucumerinum in diving ducks
Authors: Scott Marilyn E. , Rau M. E. , McLaughlin J. D. 
Published: June 2009

SUMMARYExperimental infections of mallards (Anas platyrhynchos L.) with Typhlocoelum cucumerinum sisowi (Skrjabin, 1913) and of canvasbacks (Aythya valisineria (Wilson)) with Typhlocoelum cucumerinum cucumerinum (Rudolphi, 1809) revealed significant differences in various parameters of the life-cycle in the definitive host. Both T. c. sisowi and T. c. cucumerinum migrate to the trachea via the abdominal cavity, air sacs and lungs, although T. c. cucumerinum migrate more quickly and more synchronously than T. c. sisowi. Typhlocoelum c. sisowi has a shorter expected life-span than T. c. cucumerinum but grows and reaches maturity more quickly than T. c. cucumerinum. Evidence suggests that T. c. cucumerinum has a higher fecundity than T. c. sisowi. These differences in the patterns of migration, growth and development are related not only to differences between the two host species but also to differences intrinsic to the parasites, and serve to provide biological support for considering them as separate sub-species.
Energy utilization of infectiveAncylostoma tubaeformelarvae
Authors: Croll Neil A. 
Published: June 2009

It has been demonstrated that under prolonged experimental conditions lipid is utilized most quickly under optimal conditions of tonicity, gaseous exchange, pH and sensory stimulation. There is good evidence that activity may be an appreciable energy-consuming process. It has been deduced, however, that the low Reynold's number means viscous forces dominate locomotory energy consumption, and work done is proportional to the square of the velocity. Osmoregulation in hypotonic media and tolerance of hypertonic media do not require appreciable energy.Locomotion is only possible in limited environmental conditions, and these may also be conditions of peak basal metabolism. Larvae are able to enter quiescence which is not energy-demanding, in poor conditions. Larvae can survive anaerobiasis, but finally die without reduction in lipid and cannot convert lipid to carbohydrate for anaerobic metabolism.The help of Mrs Helen Foreman in staining the larvae and for statistical analyses, and of Mr J. M. Smith is greatly appreciated. I would like to thank Dr Elizabeth U. Canning for kindly providing the microdensitometer and Professor G. S. Nelson and Dr D. A. Denham for enabling us to establishA. tubaeformein our cats. The generous support of the British Medical Research Council is much appreciated.
Feeding and lipid synthesis of Ancylostoma tubaeforme preinfective larvae
Authors: Croll Neil A. 
Published: June 2009

The growth curve, rate of neutral unbound lipid synthesis, and relationship between morphogenesis and lipid reserve have been studied at 30 °C. The feeding process, including a theoretical calculation of bacterial requirements of preinfective larvae, is presented, together with some measurements of the most important variables in ingestion, expulsion of water through the anus, and its dependence on larval posture is described.Larval stages have been tracked on agar; L1 are so inactive that no tracks were obtained; L2 show short, irregular tracks, and infective larvae strong, long and straighter tracks. The locomotory activity of L2s is primarily for feeding, whereas L2s are adapted for dispersion and host location.I thank Mr J. M. Smith for tracking the larvae and Mrs Helen Foreman for staining them, Dr Elizabeth U. Canning for making available the scanning microdensitometer and Professor G. S. Nelson and Dr D. A. Denham for enabling us to establish A. tubaeforme in cats. Finally the generous support of the British Medical Research Council is appreciated.
Short-interval absorption and metabolism of some amino acids in Trypanosoma gambiense
Authors: Chappell L. H. , Southworth G. C. , Read C. P. 
Published: June 2009

During 2 min incubations of Trypanosoma gambiense (bloodstream form) with [U-14C]glucose (1 mM) over 60% of absorbed label was detected in free alanine. In the presence of 12·5 mM unlabelled alanine, the amount of alanine synthesized from glucose was reduced by less than 10%. These data support previous observations on the high level of transaminase activity in African human trypanosomes.Alanine, aspartate and glutamate were metabolized to various other free amino acids whereas a significant amount of label derived from [14C]arginine could not be accounted for by amino acid assay.The sulphur containing amino acids, cysteic acid and taurine, were apparently synthesized from alanine, glutamate and arginine. The significance of these syntheses is poorly understood.Following incubations of trypanosomes for 2 min in exogenous amino acids the internal free pool became imbalanced due to accumulation and metabolism of the substrate amino acid.Evidence obtained indicated that the level of free endogenous glutamate may be rate limiting for the glutamate-pyruvate transaminase system.
An analysis of the course of infection of Moniliformis dubius (Acanthocephala) in rats
Authors: Crompton D. W. T. , Walters D. E. 
Published: June 2009

An analysis of the course of infection of mixed oral infections of 12 cystacanths of Moniliformis dubius in 174 male and 179 female Wistar rats has been undertaken.There was a marked decline in the average recovery rate of worms of both sexes from hosts of both sexes during the course of the infection.Female worms from both male and female rats showed, on average, a greater power of survival than male worms from the third period (10–13 weeks) onwards.Male rats were found to retain, on average, a greater number of worms of both sexes than female rats.We wish to thank Miss Susan Arnold and Mr David Barnard for excellent technical help.
Babesia pantherae sp.nov., a piroplasm of the leopard (Panthera pardus)
Authors: Dennig H. K. , Brocklesby D. W. 
Published: June 2009

A large Babesia species was found in a leopard (Panthera pardus) in Kenya. It was established in domestic cats but no other animal was found to be susceptible. The parasite has been compared with other piroplasms of felids and it was found to differ from them in some significant characters. It was established as a new species and named Babesia pantherae.We would like to thank Miss B. O. Vidler for her assistance, Dr S. F. Barnett for many helpful discussions and Professor N. D. Levine for pointing out the need for this description.The parasite was isolated when we were working at the East African Veterinary Research Organization at Muguga in Kenya and we are most grateful to that organization for facilities.
Effects of mebendazole on the encysted phase of Trichinella spiralis in the rat: an electron-microscope study
Authors: Nollin Sonja De , Borgers M. , Vanparijs O. , Van Den Bossche H. 
Published: June 2009

The ultrastructural changes in the encysted phase of Trichinella larvae, during and after treatment of the rat with mebendazole, were studied.The earliest modifications in the infected area concerned the immediate larval environment (matrix). These degenerative changes in the matrix were seen before any alteration could be observed in the larvae.Subsequently, oedematous swelling, intracellular vacuolization and loss of glycogen were noted in the larval cells.Together with the progressive involution of the larvae and their matrix, inflammatory and immunocompetent cells invade the infected area and penetrate the altered capsule. Calcification of the larvae and massive infiltration of mononuclear phagocytes with subsequent elimination of the calcified remnants were the prominent features in the first weeks after treatment. The infected areas were completely cleared from larval and matrix residues 50 days after the end of treatment and a nearly normalized tissue was seen from day 111 after treatment.
Seasonal abundance ofNeoechinorhynchus cylindratustaken from largemouth bass (Micropterus salmoides) in a heated reservoir
Authors: Eure H. 
Published: June 2009

Samples of largemouth bass were collected from Par Pond located on the Energy Research and Development Administration's Savannah River Plant in Aiken, South Carolina, from June 1972 to May 1973 inclusive. The sampling stations reflected water temperatures which were both normal and greater than 10°C above normal for the area. The acanthocephalanNeoechinorhynchus cylindratuswas the dominant species found in the bass sampled. Incidences of infection for this parasite were generally greater than 95% regardless of location. A pronounced seasonal cycling pattern in the intensity of infection was noted in both thermal regions. Significant differences, however, in the mean density ofN. cylindratusper host in fish taken from the heated area as compared with unheated areas were noted.Turnover in the acanthocephalan population was measured by following the percentage of individuals less than 2 mm long. Fall proved to be the most intense parasite recruitment season, followed by maturation of the parasite and subsequent loss from the fish host.The principal factors responsible for the seasonal incidence and intensity patterns are considered to be changes in the fish feeding behaviour and annual temperature regimes.
Fasciola hepatica: a transmission and scanning electron microscopical study of the apical surface of the gastrodermal cells
Authors: Threadgold L. T. 
Published: June 2009

SummaryThe ultrastructure of the apical surface of the gastrodermal cells of Fasciola hepatica has been investigated by transmission (TEM) and scanning electron microscopy (SEM). The surface is composed of triangular or rhomboidal lamellae which may be subdivided at their margins. The lamellae may have a smooth or wrinkled surface and apical microvilli of varied length and number. Spherical bodies may be attached to the sides or tips of the lamellae.The lamellae of individual cells are grouped to form either a series of overlapping, concentrically arranged leaflets or a series of sinuous lamellae running parallel with the cell's long axis. Lamellae may also divide, anastomose, or cross from one cell to an adjacent cell.The lamellae have an internal skeleton consisting of laterally orientated ‘fibres’ which are more or less evenly spaced and parallel with the cell's apical plasma membrane. There is some evidence that the ‘fibres’ are composed of a number of very small tubules in a dense matrix. The ‘fibres’ are connected to the plasma membrane and to each other by dense amorphous material.
Immunological interactions between Trichinella spiralis and Trichuris muris in the intestine of the mouse
Authors: Burce R. G. , Wakelin D. 
Published: June 2009

In outbred (CFLP) and inbred (NIH) mice, the inflammatory response which is thought to be party responsible for the expulsion of Trichinella spiralis from the mid-region of the small intestine, also seemed to be largely responsible fo rthe simulataneous (i.e. early) expulsion of Trichuris muris from the caecum and large intestine during concurrent primary infections. The intractive explusion operated only when the concurrent infections were timed to produce T. Spiralis expulsion before T. muris expulsion would normally occur and the effect persisted for several days after T. Spiralis has been expelled.Interactive expulsion wasss depressed during application of the nonsteroid, anti-inflammatory drug indomethacin and by T-cell expulsion of T. spiralis. These results indicate that a T-cell mediated inflammatory response was probably the basis of the interaction.When the timing of the infections was altered such that the expulsion of T. spiralis there was no reciprocal ecpulsion of the latter. Mice immunized againest one or the other species did not show cross-immunity on heterologus challenge, confirming that the interaction did not involve similar antigens in the two species. The interactive expulsive response is considered as an example of an indirect cross-immunity.
The regulation of host population growth by parasitic species
Authors: Anderson R. M. 
Published: June 2009

SummaryThe nature of parasitism at the population level is defined in terms of the parasite's influence on the natural intrinsic growth rate of its host population. It is suggested that the influence on this rate is related to the average parasite burden/host and hence to the statistical distribution of parasites within the host population.Theoretical models of host–parasite associations are used to assess the regulatory influence of parasitic species on host population growth. Model predictions suggest that three specific groups of population processes are of particular importance: over-dispersion of parasite numbers/host, density dependence in parasite mortality or reproduction and parasite-induced host mortality that increases faster than linearly with the parasite burden. Other population mechanisms are shown to have a destabilizing influence, namely: parasite-induced reduction in host reproductive potential, direct parasite reproduction within the host and time delays in the development of transmission stages of the parasite.These regulatory and destabilizing processes are shown to be commonly observed features of natural host-parasite associations. It is argued that interactions in the real world are characterized by a degree of tension between these regulatory and destabilizing forces and that population rate parameter values in parasite life-cycles are very far from being a haphazard selection of all numerically possible values. It is suggested that evolutionary pressures in observed associations will tend to counteract a strong destabilizing force by an equally strong regulatory influence. Empirical evidence is shown to support this suggestion in, for example, associations between larval digeneans and molluscan hosts (parasite-induced reduction in host reproductive potential counteracted by tight density-dependent constraints on parasite population growth), and interactions between protozoan parasites and mammalian hosts (direct parasite reproduction counteracted by a well-developed immunological response by the host).The type of laboratory and field data required to improve our understanding of the dynamical properties of host–parasite population associations is discussed and it is suggested that quantitative measurement of rates of parasite-induced host mortality, degrees of over-dispersion, transmission rates and reproductive and mortality rates of both host and parasite would provide an important first step. The value of laboratory work in this area is demonstrated by reference to studies which highlight the regulatory influence of parasitic species on host population growth.