Fasciola hepatica: Migration of newly excysted juveniles in resistant rats

Using transmission and scanning electron microscopy, the early migration of juvenile Fasciola hepatica was examined in naive and resistant rats. In naive rats, the migration of flukes to the peritoneal cavity was uneventful. In resistant rats, flukes were rapidly coated with antibody whilst still in the gut lumen and a proportion of the flukes were unable to penetrate the intestinal wall. Those that did penetrate were unharmed as they crossed the gut wall, but on entering the peritoneal cavity they were coated with antibody and host cells including eosinophils, neutrophils, macrophages, and mast cells. Eosinophils were seen degranulating onto the fluke surface, and this appeared to result in the erosion of the tegumental syncytium.     

A filamentous virus of the honey bee

A common and widespread disease of honey bees, Apis mellifera, is caused by an unoccluded, Feulgen-positive, filamentous nuclear virus. Ovoid viral particles seen in diseased bee hemolymph consisted of a folded nucleocapsid within a viral envelope and were 0.40 by 0.10 μm. Virions with unfolded nucleocapsids were about 3060 by 60 nm. The disease was transmissible to bees both per os and by injection, but efforts to infect oriental cockroaches, Blatta orientalis, and the greater wax moth, Galleria mellonella, failed. The disease is apparently the same as that described as a rickettsial disease of European bees.     

Ultrastructure of Red-Sore Lesions on Largemouth Bass (Micropterus salmoides): Association of the Ciliate Epistylis sp. and the Bacterium Aeromonas hydrophila*

SYNOPSIS. Epizootic outbreaks of red-sore disease in several reservoirs in the southeastern United States have been reported to cause heavy mortality among several species of fish having sport and commercial value. The etiologic agent is said to be the peritrich ciliate Epistylis sp.; secondary infection by the gram-negative bacterium Aeromonas hydrophila produces hemorrhagic septicemia which results in death. However, in recent studies on the largemouth bass Micropterus salmoides, Epistylis sp. could be isolated from only 35% of 114 lesions from 114 fish, while A. hydrophila was found in 96% of the same lesions. Transmission and scanning electron microscopy of lesions associated with red-sore disease indicate that neither the stalk nor the attachment structure of Epistylis sp. have organelles capable of producing lytic enzymes. Since other investigators have shown that A. hydrophila produces strong lytic toxins, and in absence of evidence to the contrary, it is concluded that Epistylis sp. is a benign ectocommensal and that A. hydrophila is the primary etiologic agent of red-sore disease.     

Fine Structure of the Oocyst Wall of Eimeria nieschulzi

SYNOPSIS. Oocysts of Eimeria nieschulzi from the laboratory rat, Rattus, norvegicus , were studied by scanning and transmission electron microscopy. Oocysts had a rough outer wall with apparent random depressions. The oocyst wall is composed of 2 layers: an osmiophilic outer layer consisting of a rough external and smooth internal surface, and a relatively thick, electron-lucent inner layer. The outer layer is composed of a dense, coarsely granular matrix. The inner layer consists of homogeneous fine granular material interspersed with coarse osmiophilic granules and contains one closely applied membrane on the outermost surface. Several raised lenticular areas are seen on the coarse outer surface of the inner layer. These layers are 102 (75–128) and 176 (135–204) nm thick, respectively.
The sporocyst wall is thin, consisting of 3 to 4 unit membranes, and measures 27 (18–34) nm thick.     

The Structure and Morphogenesis of the Ventral Ciliature in Paraurostyla hymenophora*

SYNOPSIS. The structure and morphogenesis of the ventral ciliature of Paraurostyla hymenophora (Stokes) are described. The oral primordium apparently originates in association with transverse cirrus #6, from which it migrates anteriorly simultaneous with kinetosomal proliferation. The primordium eventually forms an elongate ciliary field from which the future opisthe's fronto-ventro-transverse (FVT) and undulating membrane primordial fields arise. Concomitantly, the future proter's FVT primordial field is initiated by the disaggregation of frontal cirri #4, #5, and #6. Primordia then develop simultaneously within marginal and ventral cirral rows by a disaggregation of cirri within the respective rows, and do not give rise to new cirri until the FVT fields complete segregation into discrete cirri. Near the completion of cirral production from the FVT primordia, each ventral cirral primordium (VCP) forms the 2 rightmost transverse cirri. Segregation of new cirri within the marginal cirral primordia and VCP then occurs, eventually replacing all old cirri within their respective marginal and ventral cirral rows. At the end of cortical morphogenesis, all old ciliary organelles, with the exception of the adoral zone of membranelles, are either reorganized or replaced. These results suggest an evolutionary affinity between the ventral and marginal cirral rows and raise questions about the control of the developmental competence of individual primordia.     

Development of the olfactory organ in the rainbow fish Nematocentris maccullochi (Atheriniformes,Melanotaeniidae)

Summary The development of the olfactory organ in the rainbow fish, Nematocentris maccullochi, was studied using scanning and transmission electron microscopy; it was compared with the developmental process in other teleosts, especially in the closely related atherinids and cyprinodonts. The formation of the nares parallels that in atherinids, salmonids, cyprinids and heterosomats, but differs from that found in cyprinodonts. Another ontogenetic feature in which the olfactory organs of the rainbow fish and also of atherinids differ from those of cyprinodonts, is the occurrence of transitory kinociliary cells which disappear during the postlarval period. The divergent evolutionary pathways are discussed with reference to experimental investigations. During development, ciliated and microvillous receptor cell types occur. At the primary larval stage ciliated receptor neurons are exclusively present. At a later stage the microvillous type develops and becomes equal in frequency. Thus, the microvillous receptor represents a separate type of olfactory neuron and is not a progenitor of the ciliated receptor cell.This work was supported by the Deutsche ForschungsgemeinschaftThe authors would like to acknowledge Prof. G. Hartmann (Hamburg) and Prof. V. Storch (Kiel) for use of the SEM, Prof. K. Seifert (Neumünster) for valuable discussion. For skillful technical assistance we are indebted to Miss C. Heim, Mrs. K. Hoffmann, and Mr. H.P. Dreyer     

Plasmodium gallinaceum: Transmission-blocking immunity in chickens. II. The effect of antigamete antibodies in vitro and in vivo and their elaboration during infection

Heat-inactivated serum from chickens with transmission-blocking immunity to Plasmodium gallinaceum prevented the in vitro development of oökinetes from gametocytes of P. gallinaceum only when present during the period between the initiation of gametogeriesis and the release of the microgametes. When added after this time immune serum failed to suppress oökinete development. Immune serum did not prevent the formation of gametes from gametocytes. These results are interpreted to indicate that immune serum contains factors which prevent fertilization of the malarial gametes but which do not affect the development of the zygote once fertilization has taken place. Two distinct reactions of malarial gametes with serum from chickens with transmission-suppressing immunity are described—the gamete-agglutination (AG) reaction and the microgamete surface-fixation (SF) reaction. Both reactions were associated with the immunoglobulin fraction of immune serum. The presence of SF antibodies during a blood infection correlated closely with effective transmission-blocking immunity in vivo; AG antibodies, on the other hand, were present in various circumstances in the absence of transmission-blocking immunity. AG and SF antibodies occurred not only in birds immunized with P. gallinaceum-gamete preparations but also during or following infections in unimmunized birds; SF antibodies appeared only following the peak of asexual infection in unimmunized birds and were of low titer. In immunized birds blood infections following live challenge invariably boosted low levels of SF antibodies. The results of immunization of chickens and Rhesus monkeys with gametes of their respective malaria parasites, P. gallinaceum and P. knowlesi, are compared.     

Plasmodium gallinaceum: transmission-blocking immunity in chickens. I. Comparative immunogenicity of gametocyte- and gamete-containing preparations.

Immunization of chickens by intravenous inoculation of preparations derived from blood infected with Plasmodium galinaceum led to reduced infectivity to mosquitoes (Aedes aegypti) during subsequently induced blood infection but had little effect on the course of asexual parasitemia. Immunization with preparations containing intracellular gametocytes was much less effective than immunization with preparations in which the extracellular gametes had been released during gametogenesis (emergence and exflagellation) prior to inoculation. By far the most effective material were preparations of partially purified gametes of both sexes. Three weekly inoculations of this material resulted in 99.99% suppression of infectivity to mosquitoes during subsequently induced blood infection. Preparations of purified gamete material from which gametes of one or another sex were absent were considerably less effective as transmission-blocking immunogens than the mixed gamete preparation. It is possible that the two sexes of gamete act synergistically to induce transmission-blocking immunity.     

Biological effects of a 765-kV transmission line: Exposures and thresholds in honeybee colonies

Honeybee colonies exposed under a 765-kV, 60-Hz transmission line at 7 kV/m show the following sequence of effects: 1) increased motor activity with transient increase in hive temperature; 2) abnormal propolization; 3) impaired hive weight gain; 4) queen loss and abnormal production of queen cells; 5) decreased sealed brood; and 6) poor winter survival. When colonies were exposed at 5 different E fields (7, 5.5, 4.1, 1.8, and 0.65–0.85 kV/m) at incremental distances from the line, different thresholds for biologic effects were obtained. Hive net weights showed significant dose-related lags at the following exposures: 7 kV/m, one week; 5.5 kV/m, 2 weeks; and 4.1 kV/m, 11 weeks. The two lowest exposure groups had normal weight after 25 weeks. Abnormal propolization of hive entrances did not occur below 4.1 kV/m. Queen loss occurred in 6 of 7 colonies at 7 kV/m and 1 of 7 at 5.5 kV/m, but not below. Foraging rates were significantly lower only at 7 and 5.5 kV/m. Hive weight impairment and abnormal propolization occur at lower E-field intensity than other effects and limit the “biological effects corridor” of the transmission line to approximately 23 m beyond a ground line projection of each outer phase wire. Intrahive E fields of 15–100 kV/m were measured with a displacement current sensor. Step-potential-induced currents up to 0.5 μA were measured in an electrically equivalent bee model placed on the honeycomb in a hive exposed at 7 kV/m. At 1.8 kV/m body currents were a few nanoamperes, or two orders of magnitude lower, and these colonies showed no effects. E-field versus electric shock mechanisms are discussed.     

Brugia malayi,Brugia pahangi, and Brugia patei: Pulmonary pathology in jirds, Meriones unguiculatus

The chronological development of pulmonary lesions due to subperiodic Brugia malayi and related species was studied in the jird, Meriones unguiculatus. Major pathologic changes included (1) granulomas induced by larvae and adults, (2) obstructive endarteritis, and (3) chronic interstitial inflammation with degenerating microfilariae. The majority of pulmonary granulomas were initiated near the time of the final molt, about 30 days postinoculation, followed by involution and formation of residual vascular lesions over the next several months. A minority of granulomas arose about sexually mature adult worms and showed a characteristic sequence of development along the length of these worms. Ultrastructural observations suggested that within granulomas internal structures of the worm underwent an autolytic-like disintegration, while the cuticle remained intact. A material, presumably of parasitic origin, then appeared between the cuticle and adherent epitheloid and giant cells and was subsequently phagocytized by these cells. Obstructive endarteritis appeared to peak at about the time of the final molt, and became largely fibrotic by 125 days postinoculation; electron microscopy of the subintimal infiltrates revealed a variety of cells including inflammatory cells and others interpreted as modfied cells of vascular origin (smooth muscle cells and two types of endothelial cells).Parasitological data suggested that both larvae and adults migrated to the lungs and that mating occurred here, rather than in peripheral sites of development. In terms of development, reproduction and survival, the pulmonary arteries of the male jird offered a suitable alternative for the localization of these primarily lymphatic filariae; our results thus suggest that the pulmonary localization of these worms should not be considered indicative of an aberrant mode of development. The failure of female jirds to develop detectable peripheral microfilaremia was associated with a high rate of infertility among female worms, rather than pulmonary sequestration or destruction of microfilariae.