bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent advances in our understanding of pentastomid reproductive biology
Authors: Riley J. 
Published: June 2009

SUMMARYPentastomids are arthropod parasites which attain maturity in the respiratory tracts of vertebrates. All pentastomids exhibit an obvious sexual dimorphism in that fully mature females are invariably much bigger than males. Unusually though, copulation, which happens only once in the lifetime of females, occurs when both sexes are approximately the same size and the uterus of the female is undeveloped. This is because sperm is stored in spermathecae which, being positioned at the junction of the oviduct and uterus, become more remote from the vagina as the uterus elongates during development. The provision of spermathecae for sperm storage allows oocytes, shed continuously from the ovary, to be fertilized from time to time. What renders this process quite remarkable, and possibly unique, is the extreme length of the patent period. In one species this can extend up to an estimated 10 years and is associated with an egg production of about 106eggs/female/year. Spermathecal structure provides some clues as to how prolonged sperm storage and the continuous fertilization of oocytes is accomplished. The upper region of the access duct is a narrow, chitinized tube which tapers to as little as 3 μm diameter at the point of entry into the spermatheca. The chitinous (?) lining of the spermatheca is relatively impermeable and apparently functions to totally isolate sperm from external influences: stored sperm are arranged in bundles and whorls and remain totally quiescent and inactive during the storage period. The entire spermatheca is invested by muscle fibres, the contraction of which will express small numbers of sperms through the narrow access duct. These are then reactivated by secretions from the female reproductive tract: the extreme narrowness of the spermathecal duct provides the fine adjustment of the system. The narrowness of the duct also creates problems during the process of insemination, since sperm discharged directly into the female reproductive tract would be unlikely to find the spermatheca through such a structure. Accordingly, the male cirrus is much modified to directly penetrate the spermathecal duct during copulation. Sperms, stored in the male seminal vesicle, are apparently activated prior to sperm transfer, and swim along the cirrus to be guided directly into the spermathecal lumen. Some unusual variations on the normal pentastomid life-cycle are discussed.
Different levels of immunity to Schistosoma mansoni in the mouse: the role of variant cercariae
Authors: Smith M. A , Clegg J. A. 
Published: June 2009

SUMMARYVery variable levels of immunity to a second infection with Schistosoma mansoni were recorded in 7 strains of mice, 12–15 weeks following a small primary infection. When 2 or more strains of mice were assayed at the same time, less variation occurred within the experiment than between different experiments. This evidence suggested variation between pools of cercariae as the main cause of variability in immunity. In direct experiments in one strain of mouse, 2 different pools of cercariae stimulated widely different levels of immunity to the same challenge. Conversely, challenge infections drawn from different pools showed different susceptibility to immunity stimulated by the same primary infection. Individual clones of cercariae, from snails infected with single miracidia, showed a high level of susceptibility to immunity stimulated by a small bisexual infection, or were not susceptible at all. Antigenic polymorphism is the most likely explanation for the differences observed between clones of cercariae. However, indirect immunofluorescence showed the presence of at least 1 common antigen on the surface of schistosomula derived from different clones of cercariae and clone-specific antigens have not been detected.
Evasion of the haemocytic defence reaction of certain insects by larvae of Hymenolepis diminuta (Cestoda)
Authors: Lackie Ann M. 
Published: June 2009

SummaryLarvae of Hymenolepis diminuta develop in the haemocoele of the beetles Tribolium and Tenebrio, and of the locust Schistocerca gregaria, without being encapsulated by haemocytes. The mechanism of this evasion of the haemocytic defence reaction has been examined using various techniques. Larvae grown in culture and injected into S. gregaria have few or no haemocytes adherent even after 8 h, although latex beads injected at the same time have been thickly encapsulated. This, and results of transplanting cysticercoids and host tissue between different insect species, suggests that the surface of the larvae may bear an inherent similarity to the surface of host tissues and thus escape recognition as ‘not-self’ by the host’s haemocytes.
Micromotility meter: an instrument designed to evaluate the action of drugs on motility of larval and adult nematodes
Authors: Bennett J. L. , Pax R. A. 
Published: June 2009

SUMMARYAn instrument for measuring the motility of larval and adult nematodes is described along with an analysis of its use as a tool to analyse drug action on these parasites. Motility was detected from larval parasites ofNippostrongylus brasiliensisandAscaris suumin the absence and presence of various anti-nematodal drugs. These agents produced, within 48 h, a significant decrease in larval parasite motility. The instrument was also capable of detecting the motility ofCaenorhabditis elegans, adult femaleBrugia pahangiand their response to anti-nematodal drugs. The design of the instrument allows us to accurately measure motility in a single sample within 60 sec.
Parasite–host relationships during the development of Eimeria dispersa Tyzzer 1929, in the turkey (Meleagris gallopavo gallopavo) with a description of intestinal intra-epithelial leucocytes
Authors: Millard B. J. , Lawn A. M. 
Published: June 2009

SUMMARYAn electron microscopical study was made on the development of Eimeria dispersa in the small intestine of the domestic turkey. Turkey poults, 10–14 days of age, were inoculated with oocysts and pieces of intestinal tissue were fixed at intervals between 3·5 and 114 h after inoculation. Sporozoites were occasionally seen in enterocytes but more often in ‘pale’ cells closely resembling lymphocytes. These cells were insinuated between enterocytes and in this study are referred to as intestinal intra-epithelial leucocytes (IEL). Maturation of the first-generation of schizogony occurred in this type of cell. Other generations of schizonts and gametogony occurred in epithelial cells and were characterized by the presence of ‘spines’ arranged around the parasitophorous vacuole extending into the cytoplasm of the host cell. A limited study of the parasite in the Bobwhite quail, Colinis virginianus, showed that development occurred in similar cells to those of the turkey. The ‘spines’, which were characteristic of later stages of E. dispersa in the turkey, were also present in this host and seemed to be a characteristic of E. dispersa, not of the host species.
Effect of low temperature on development of the coccidium Eimeria funduli in the Gulf killifish
Authors: Solangi M. A. , Overstreet R. M. , Fournie J. W. 
Published: June 2009

SUMMARYEimeria funduli, a coccidium infecting the liver and pancreas of killifishes and requiring an intermediate host, was allowed to develop at 22±2 °C for 5, 10, 15 or 20 days (schizont through zygote stages) in Fundulus grandis and was then exposed to 10·0±0·5 °C for 20 days or to 7·0±0·5 °C for 5 or 20 days. Both low temperature treatments inhibited all developmental stages, except for the case of fish infected for 5 days before exposure to 7 °C in which infections were eliminated. Returning fish back to a temperature of 22 °C for 20 days resulted in resumed development of all stages at the same or somewhat reduced rate. In all cases, intensity of infections was greatly reduced during exposure to low temperatures. Many organisms exhibited abnormalities. Gamonts and zygotes were atrophied or disintegrated within their parasitophorous vacuoles in all exposures and, in fish exposed to 7 °C for 20 but not 5 days, about 30% of the oocysts were abnormal, with from 1–8 sporoblasts. Areas of degeneration or necrosis incorporated aggregates and single parasites in both the pancreas and the hepatic parenchyma. The granulocytic inflammatory response, which at 22 °C was normally restricted to the period spanning development of gamonts and formation of the oocyst wall, was inhibited or delayed from infiltrating infected, diseased areas at low temperatures. The response intensified after cold-exposed fish were returned to 22 °C. A fibroid, non-granulocytic response occurred in fish introduced 5 days post-infection to 10°C before being returned to warm water. Two other types of lesion occurred in the pancreas. The first could develop into necrosis and was associated with low temperature; it did not always involve infected tissue. The other, a degenerating focal alteration, was not necessarily associated with infections or low temperatures.
Passive immunization of mice againstSchistosoma mansoniwith an IgM monoclonal antibody
Authors: Smith M. A. , Clegg J. A. , Snary D. , Trejdosiewicz A. J. 
Published: June 2009

SUMMARYTwo hybridomas secreting monoclonal IgM antibody toSchistosoma mansonihave been isolated following fusion of spleen cells from Balb/c mice immunized with livingS. mansoniand NS1 myeloma cells. One monoclonal IgM antibody (WP66.4) mediated about the same level of passive protection against a challenge infection as immune serum from mice with a chronicS. mansoniinfection. The other monoclonal antibody (WP66.2) did not give a significant level of passive protection. This result indicates that the effective monoclonal antibody recognizes an antigen which may be a valuable candidate for experimental vaccination.In vitroone monoclonal antibody (WP66.4) caused a much higher level of complement-dependent cytotoxicity than the other (WP66.2), suggesting a possible mechanism for the effect observedin vivo. With indirect immunofluorescence both monoclonal antibodies reacted with surface determinants on livingS. mansonischistosomula, adult worms and miracidia but these determinants were not detected on cercariae or lung schistosomula. Neither monoclonal antibody cross-reacted withS. haematobiumschistosomula orFasciola hepaticametacercariae, indicating a possible use for these reagents in differential diagnosis ofS. mansoniinfections.
The effect of worm, age, weight and number in the infection on the absorption of glucose by Hymenolepis diminuta
Authors: Henderson D. 
Published: June 2009

SummaryIn Hymenolepis diminuta the in vitro rate of absorption of glucose/unit dry weight of worm falls with increasing worm age, with increasing worm weight and as the number of worms in an infection is increased. In a 6 mM solution of glucose, a 5 mg (dry weight) worm from a 7 or 8 worm infection absorbed 80 µmoles/g dry weight/5 min whereas a 60 mg worm, also from a 7 or 8 worm infection, absorbed only 35µmoles/g dry weight/5 min. This change in the rate of absorption is, at least partly, thought to be due to changes in the relative surface area: weight ratio during growth of the worm.The kinetic parameter, Kt glucose, increased from 1.1 mM for a 5 mg (dry weight) worm from a 7 or 8 worm infection to 2 mM for a 60 mg worm. This change in the functioning of the glucose transport system may indicate that there are two components of the glucose transport system – or two separate systems – one with a low Kt and one with a high Kt, the ratios of which change during worm growth.The smaller the number of worms in an infection the greater the rate of glucose absorption. Using 8–day–old worms in a 6 mM glucose solution, 1 worm from a single worm infection absorbs 111 μmoles/g dry weight/5 min, 1 worm from a 7 or 8 worm infection absorbs 88 μmoles/g dry weight/5 min and 1 worm from a 45–50 worm infection absorbs 77 μmoles/g dry weight/5min. The significance of this is discussed with reference to the ‘crowding effect’ in tapeworms.
Host restriction, morphology and isoenzymes among trypanosomes of some British freshwater fishes
Authors: Letch C. A. 
Published: June 2009

SUMMARYTrypanosomes were studied from the blood of 6 species of small British fish caught in the River Lee. Morphologically the trypanosomes from the blood ofNemacheilus barbatulusL.,Phoxinus phoxinusL.,Cottus gobioL.,Gobio gobioL.,Gasterosteus aculeatusandPungitus pungitusL. were indistinguishable. Cross-transmission experiments using syringe passage of culture forms and also the leech vectorHemiclepsis marginatashowed that the trypanosomes were not host specific. The isoenzyme patterns of culture forms fromN. barbatulusandP. phoxinuswere identical for 11 enzymes studied. The trypanosomes from the 6 species of fish previously classified as separate species are, on the basis of these results, regarded as a single species,Trypanosoma cobitis(Mitrophanow, 1883).
Lizard malaria: cost to vertebrate host's reproductive success
Authors: Schall J. J. 
Published: June 2009

SUMMARYPlasmodium mexicanum is a common malarial parasite of the western fence lizard, Sceloporus occidentalis, in northern California, USA. Infected female lizards store substantially less fat during the summer activity season and produce smaller clutches of eggs than do non-infected animals. Stored fat is utilized in the production of eggs; the energy content of the decrement in stored fat is approximately equal to the energy content of the average reduction in number of eggs. Thus, there is ongoing strong selective pressure on the host to evolve appropriate anti-parasite measures.
The nutritional physiology of Trichoplusia ni parasitized by the insect parasite, Hyposoter exiguae, and the effects of parallel-feeding
Authors: Thompson S. N. 
Published: June 2009

SUMMARYHost nutrition plays a major role in the nutritional physiology of Trichoplusia ni parasitized by the hymenopterous insect parasite, Hyposoter exiguae. Severely reduced growth rate characterized the host association throughout the 4th developmental stadium. This effect of parasitization, however, was indirect and growth depression of parasitized larvae was entirely accounted for by the accompanying decreased rate of food consumption. Parallel-fed larvae, that is, unparasitized larvae feeding on nutrients at the same rate as observed in ad libitum-fed parasitized individuals, displayed lower rates of growth than parasitized larvae and the latter had higher rates of assimilation. Parasitization, therefore, directly resulted in an increased rate of assimilation over that observed in uninfected insects after accounting for the effects of altered food consumption. Similarly, differences in the pattern of response to decreased dietary protein levels between parasitized and unparasitized insects could be explained on the basis of differences in their rates of food consumption
Schistosoma mansoni: the structure and elemental composition of pre-acetabular penetration gland cell secretion in pre-emergent cercariae
Authors: Davies T. W. 
Published: June 2009

SUMMARYThe structure and elemental composition of the secretory products of the pre-acetabular penetration gland cells of pre-emergent cercariae of Schistosoma mansoni have been investigated at an ultrastructural level using X-ray probe microanalysis. The secretion contains 2 types of bodies, one homogeneous and one heterogeneous with electron-lucent areas. Using a variety of fixation and sectioning techniques it has been shown that the apparent electron density of the homogeneous bodies (Type B) is the result of interaction with osmium tetroxide and stain. The small electron-lucent areas of the other type of secretory body (Type A) represent regions where granules have been leached out by processing media. X-ray analysis of cercariae still within sporocysts has indicated that these granules are very rich in calcium, and it is suggested that the calcium is absorbed by the developing cercariae through the sporocyst wall from the molluscan haemolymph.
The ultrastructure of the fore-gut of the redia of Parorchis acanthus Nicoll (Digenea: Philophthalmidae) from the digestive gland of Nucella lapillus L
Authors: Rees F. Gwendolen 
Published: June 2009

SUMMARYThe fore-gut of the redia of Parorchis acanthus is ingestive in function. It consists of a buccal cavity, suctorial pharynx and an oesophagus divided into anterior and posterior regions. The syncytial lining is continuous with that covering the body surface, except for the posterior region of the oesophagus which is lined by a separate syncytium. This latter has different cytoplasmic inclusions and the unusual feature of a single ventral nucleus in the outer cytoplasmic epidermis. Intrinsic and extrinsic muscles are responsible, respectively, for the fairly rapid passage of food through the fore-gut and for support. Secretion bodies in the epidermis are probably discharged into the lumen and pass with food into the intestine where they may be involved in extracellular digestion. Young rediae feed mainly by mouth while older, immotile rediae absorb nutrients mainly through the body surface.
Experimental studies on the transmission dynamics of the cercariae of Echinoparyphium recurvatum (Digenea: Echinostomatidae)
Authors: Evans N. A. , Gordon D. M. 
Published: June 2009

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.
Mitochondrial adenosine triphosphatase activity and temperature adaptation inSchistocephalus solidus(Cestoda: Pseudophyllidea)
Authors: Walker R. W. , Barrett J. 
Published: June 2009

SUMMARYDuring its life-cycle, the cestodeSchistocephalus solidusis parasitic in both an ectotherm (Gasterosteus aculeatus) and an endotherm (Gallus domesticus) host, and so provides an excellent model with which to study temperature adaptation in parasites. A mitochondrial fraction was prepared from the adults and plerocercoids ofS. solidusand from their respective hosts; the activities of the mitochondrial adenosine triphosphatase (ATPase) were then measured over the temperature range 1–45 °C. The plerocercoids ofS. solidusshow evidence of immediate temperature compensation; this would provide a mechanism for withstanding the abrupt temperature change experienced during infection of the final host. Analysis of the Michaelis constant data suggests that variation of Km, awith temperature may be a major factor in this immediate temperature compensation. In response to acclimation at 5 and 19°C, plerocercoid ATPase showed inverse or paradoxical rate compensation, as did the enzyme from the fish host. Acclimation at the two temperatures had no effect on the Q10or on the linearity of the Arrhenius plots for the plerocercoid mitochondrial ATPase and only a small effect on the Km a. Acclimation of the fish host again had only a small effect on the Km, aof the fish mitochondrial ATPase but, in contrast to the plerocercoid, there was also a significant effect on the Q10and the Arrhenius plots. AdultS. solidusATPase showed partial rate compensation and had a biphasic Arrhenius plot, suggesting that after infection there had been a change in the enzyme or its micro-environment. In terms of the effect of temperature on the Q10amd Km, aand in the biphasic nature of the Arrhenius plot, the mitochondrial ATPase of adultS. solidusshowed similarities with the enzyme from its bird host.
Transstadial transmission of Theileria annulata through common ixodid ticks infesting Indian cattle
Authors: Bhattacharyulu Y. , Chaudhri R. P. , Gill B. S. 
Published: June 2009

Transstadial transmission of Theileria annulata with Hyalomma anatolicum anatolicum, H. dromedarii and H. marginatum isaaci, and Haemaphysalis bispinosa, Rhipicephalus haemaphysaloides haema-physaloides and Boophilus microplus was determined.It was found that the infection was successfully transmitted by H. a. anatolicum from larva to nymph and nymph to adult in all attempts. When larvae were fed on an infected calf the succeeding adults transmitted the infection when the intervening nymphs fed on a rabbit (nonsusceptible host) but not when fed on a calf (susceptible host). Infective adult ticks transmitted the parasite during the first 24 h of feeding on a calf. When the feeding was interrupted after 24 h, and the tick transferred to another calf, the infection was transmitted to the latter as well.H. dromedarii successfully transmitted the infection from larva to nymph and from nymph to adult.Larvae of H. marginatum isaaci did not feed on calves but the infection was successfully transmitted from nymph to adult.Haemaphysalis bispinosa, Rhipicephalus h. haemaphysaloides and Boophilus microplus did not transmit Th. annulata from larva to nymph to adult.
Genetic control of immune responses to parasites: immunity to Trichuris muris in inbred and random-bred strains of mice
Authors: Wakelin P. 
Published: June 2009

A comparison has been made of the responses of random-bred CFLP and inbred NIH mice to infection with Trichuris muris. Random-bred mice showed greater variation in worm burdens and less uniformity in worm expulsion. Irradiation prior to infection reduced variation, but did not increase the mean level of infection above that shown by the most susceptible unirradiated mice. In NIH mice, however, irradiation raised the level of infection in all mice. The factors responsible for variation between CFLP mice and for the level of infection in NIH mice came into play after the fifth day of infection and were inactivated by cortisone acetate. It is suggested that these factors are immunologically mediated and under direct genetic control. Uniformity of infection and expulsion in NIH mice is therefore seen as a consequence of genetic uniformity; variability in CFLP mice as a consequence of genetic variation.The time of worm expulsion was found to differ markedly between inbred strains of mice. Hybrid progeny showed the expulsion time characteristic of the parental strain with the most rapid expulsion; greater resistance was therefore inherited as a dominant characteristic. The genetic control of immunity to T. muris is discussed in the context of the antibody- and cell-mediated components of the expulsion process.
Carbon dioxide fixation in trypanosomatids
Authors: Klein R. A. , Linstead D. J. , Wheeler M. V. 
Published: June 2009

Fixation of carbon dioxide has been demonstrated for extracts fromCrithidia fasciculata, Trypanosoma megaandTrypanosoma brucei bruceibloodstream and culture forms. The enzymes involved in this fixation were found to be ADP-stimulated phosphoenolpyruvate carboxykinase (E.C. 4. 1. 1. 32), ‘malic’ enzyme (E.C. 1. 1. 138–40) and pyruvate carboxylase (E. 0. 6. 4. 1. 1). The subcellular localization of these enzymes has been investigated in all three organisms. Products of short and long term fixation experiments were separated and identified.The importance of carboxylation reactions is discussed in relation to the maintenance of oxidized and reduced coenzyme levels.