Intergeneric interactions between Eimeria separata (Apicomplexa) and Nippostrongylus brasiliensis (Nematoda) in the rat

Ova production in Nippostrongylus brasiliensis infected rats was significantly greater than in rats singly infected with the helminth when Eimeria separata infections were introduced 4, 6 and 11 days postinoculation with N. brasiliensis. Patent periods were unaltered during concurrent infections. These results suggest that the presence of E. separata affects helminth fecundity but does not increase N. brasiliensis longevity as has been shown with E. nieschulzi.     

Peroxidase and gamma-glutamyl transpeptidase activities duringEimeria nieschulzi (Apicomplexa) and/orNippostrongylus brasiliensis (Nematoda) infections in the rat

Summary Results suggest that malabsorption of amino acids which occurs duringEimeria nieschulzi andNippostrongylus brasiliensis infections in rats is not due to impairment by intestinal inflammation of gamma-glutamyl transpeptidase activity.Supported by NIH MBRS grant RR08012-13.     

Suppression of phytohemagglutinin induced splenocyte proliferation during concurrent infection withEimeria nieschulzi andNippostrongylus brasiliensis

Summary Results suggest that infection withEimeria nieschulzi (Protozoa) interferes with splenocyte proliferation induced by infection withNippostrongylus brasiliensis (Nematoda).This study was supported by NIH MBRS Grant RR08012-15.     

Multiplication of human-derivedPneumocystis carinii in severe combined immunodeficient (SCID) mice

clinically healthy SCID mice were infected intratracheally withPneumocystis carinii (PC) of human origin. The data obtained provides unambiguous evidence that progressive multiplication of PC organisms of human origin takes place in the lungs of experimentally infected animals. SCID mice that were infected with human-derived PC also revealed a markedly greater number of mouse PC organisms in their lungs than the controls. All the SCID recipients of human PC died by day 65 post infection, whereas the controls, housed under identical conditions, started dying significantly later due to severe mouse pneumocystosis. This animal model could be used for the maintenance and propagation of human PC, and for evaluating strategies for treating human pneumocystosis.     

Phytoalexin response is elicited by a pathogen (Rhizoctonia solani) but not by a mycorrhizal fungus (Glomus mosseae) in soybean roots

Summary A container system was constructed to study the response of soybean roots to infection by mycorrhizal or pathogenic fungi. The system allows a rapid and synchronous inoculation byGlomus mosseae orRhizoctonia solani. The phytoalexin glyceollin was measured in roots of inoculated and uninoculated plants for a period of 30 days. A significantly increased content of phytoalexin was found inR. solani-infected roots as compared to uninfected control roots. However, there was no difference in the glyceollin contents of the mycorrhizal and the control roots for up to 23 days after inoculation. The accumulation of glyceollin inR. solani-infected roots was not influenced by a subsequent inoculation withG. mosseae. Moreover glyceollin accumulated in mycorrhizal plants to the same extent as in control plants when they were inoculated withR. solani. The two fungi did not mutually influence the course of infection when they were inoculated together.     

Effects of diapause and host species on some morphometric characters inTrichogramma (Hym.: Trichogrammatidae)

Adult morphology ofTrichogramma is modified by environmental conditions during the preimaginal development. For instance, the low temperatures inducing diapause cause a decrease of the ratio length of longest seta on male flagellum/width of flagellum inT. evanescens. The species of the host also influences numerous body ratios. So, in females, the development of tibiae with regard to wings is more important withScotia ipsilon than withGalleria mellonella. These results confirm the necessity of performing comparative morphological studies on individuals reared in the same conditions.     

Influence of phosphorus supply and light intensity on mycorrhizal response inPisum-Rhizobium-Glomus symbiosis

The influence of mycorrhizal colonization withGlomus mosseae on parameters of N₂ fixation and plant growth was studied in pot experiments with pea plants (Pisum sativum L.) infected withRhizobium leguminosarum and supplied with varied levels of phosphorus (P) and nitrogen (N). Reduced light intensities were used to evaluate the dependence of the microsymbionts on assimilate supply. In plants grown with low P supply, mycorrhization increased the concentration of P in shoots, and thus N₂ fixation. Reduced light intensity significantly depressed mycorrhizal colonization and nodule growth in low-P plants. When P supply did not limit plant growth and N₂ fixation, however, the percentage of mycorrhizal colonization was reduced due to the higher P status, and the microsymbionts were not impaired by low light intensities. To maximize carbohydrate supply, another experiment was carried out at high light intensity of 900 mol m^–2s^–1 and with non-limiting P supply. Nitrogen fertilization, given as starter N, enhanced plant growth, but delayed nodule formation. Towards flowering, nodulation rapidly increased, but less so inGlomus inoculated plants. After 28 days mycorrhizal plants were lower in shoot dry weight, nodule dry weight and nitrogenase activity. The results suggest that under many, but not all, environmental conditions the host plant is able to restrict mycorrhizal colonization and, thus, to prevent impairment ofRhizobium symbiosis.deceased in May 1994     

Visualization of the mitochondria ofToxoplasma gondii-infected mouse fibroblasts by the cationic permeant fluorescent dye rhodamine 123

Summary The mitochondria of living mouse fibroblasts infected withToxoplasma gondii were monitored with the cationic permeant fluorescent dye rhodamine 123. Fluorescence microscopy revealed that host cell mitochondria accumulated at the cytoplasmic surface of parasitophorous vacuoles and increased the dye uptake in the periparasitophorous vacuole asT. gondii multiplied.The author wishes gratefully to acknowledge the work of Miss Mayumi Kato and Mr. Isao Kimata in preparing the photographs. The publication cost was supported by a grant of the Ohyama Health Foundation.     

Increased susceptibility ofTrypanosoma lewisi infected,or decomplemented rats toSalmonella typhimurium

Summary Rats infected withTrypanosoma lewisi or decomplemented by injection of cobra venom factor or complement activating factor of trypanosomes were found to be more susceptible to infection withSalmonella typhimurium. Decomplemented rats subsequently infected withT. lewisi developed higher blood parasitemia than did normalT. lewisi infected rats.This project is supported by the National Research Council of Canada grant A 0068 and a grant from the International Development Research Center.     

Selectivity of alterations in skeletal fibers in chronic Chagas' disease of the mouse

Summary In mice chronically infected withTrypanosoma cruzi, the masseter muscle (rich in type II fibers) was devoid of inflammatory infiltrates and parasites. In contrast, other muscles, composed of type I and II fibers, showed a decrease of type I fibers, parasites and lesions, suggesting that inT. cruzi infection type I muscle fibers are selectively damaged.     

Infection of frog tadpoles (Amphibia) by insect parasitic nematodes (Rhabditida)

Summary Infective stage juveniles ofNeoaplectana carpocapsae (Steinernematidae) andHeterohabditis heliothidis (Heterorhabditidae) were able to penetrate through the alimentary tract of young tadpoles ofHyla regilla (Hylidae) andXenopus laevis (Pipidae) and enter the body cavity. Some infectives ofN. carpocapsae were able to release their symbiotic bacterium,Xenorhabdus nematophilus inside the host and in two cases, the nematodes developed into adult females before they perished. Tadpole mortality was associated with foreign bacteria entering the penetration holes made by the invading nematodes. The infective stage juveniles of both nematodes frequently encountered a host defense reaction upon reaching the tadpole's infective stage juveniles of both nematodes frequently encountered a host defense reaction upon reaching the tadpole's coelom.     

Cryopreservation of parasites

Summary In this review, advances in cryopreservation of helminth parasites are reported. Our own studies demonstrate that metacestodes ofEchinococcus multilocularis can be maintained in a viable state for at least 1–2 years by appropriate deep-freezing and storage in liquid nitrogen. Infective larvae of the nematodeToxocara canis cryopreserved for 1 week in liquid nitrogen were maintained after thawing in vitro in a chemically defined medium for 35 weeks. Although motility of previously deep-frozen larvae was reduced they produced secretory/excretory antigens of similar immunodiagnostic quality as those from unfrozen larvae. Whereas infective larvae of several species of trichostrongylids can be easily cryopreserved, the infective larvae of the cattle lungworm,Dictyocaulus viviparus, and muscle larvae ofTrichinella spiralis are more sensitive to damage by subzero temperatures. Therefore, survival rates after cryopreservation are low, but improvement of the cooling schedules appears to be feasible. It is concluded that cryopreservation of certain stages of helminth and protozoan parasites is a useful technique for long-term storage of defined isolates, which can contribute considerably to reducing the number of experimental animals usually required for serial passages.     

Development of DNA probes for cytotoxin and enterotoxin genes in enteric bacteria

Summary DNA probes to identify the genes encoding toxins in enteric bacteria have been developed. Use of these probes reduces the number of animals required for toxicity testing, as suspect bacteria can be directly tested for the presence of toxin. We have augmented the gene probes available by developing probes against theEscherichia coli enterotoxin LTII and shiga toxin fromShigella dysenteriae 1.The LTII gene fromE. coli 357900 was identified and characterised and a suitable internal probe was obtained. The LTII gene was found not to be common among enterobacteriae from various geographical locations. Isolates predominately of animal origin from Nigeria and Thailand hybridized with the probe.The shiga toxin gene was isolated fromS. dysenteriae 1 by a combination of in vivo and in vitro methods. An internal probe was identified and used against different serogroups ofShigella andE. coli isolated. The probe was found to hybridize withS. dysenteriae 1 isolates and also someS. flexneri andS. sonnei strains. Representatives were tested for toxin production and found to produce toxin at low levels.     

Hepatic acid hydrolases of albino rats,Mastomys natalensis and albino mice duringPlasmodium berghei infection

Summary Changes in liver acid hydrolase activities during the infection of albino rats,Mastomys or mice withPlasmodium berghei are described. B-Glucosidase, B-galactosidase and N-acetyl-B-D-glucosaminidase exhibited widely different responses with acid phosphatase and cathepsin-B the least responsive and are likely to be causally related to immunity of animals.     

Aberrant,canavanyl protein formation and the ability to tolerate or utilize L-canavanine

Summary L-Canavanine, 2-amino-4-(guanidinooxy)butyric acid, and L-arginine incorporation into de novo synthesized proteins was compared in six organisms. Utilizing L-[guanidinooxy¹⁴C]canavanine and L-[guanidino¹⁴C]arginine at substrate saturation, the canavanine to arginine incorporation ratio was determined in de, novo synthesized proteins.Caryedes brasiliensis andSternechus tuberculatus, canavanine utilizing insects;Canavalia ensiformis, a canavanine storing plant; and to a lesser extentHeliothis virescens, a canavanine resistant insect, failed to accumulate significant canavanyl proteins. By contrast,Manduca sexta, a canavanine-sensitive insect, andGlycine max, a canavanine free plant, readily incorporated canavanine into newly synthesized proteins. This study supports the contention that the incorporation of canavanine into proteins in place of arginine contributes significantly to canavanine's antimetabolic properties.     

Indirect visualization of hematopoietic colony-forming stem cell (CFUs) as a possible target cell forMycoplasma arthritidis

Summary Utilizing specific rabbit antiserum againstM. arthritidis together with complement, a portion of the marrow 7-day CFUs population of CBA mice infected with live mycoplasma organisms 1 day previously was shown to be inactivated. These cells might therefore be considered as candidate target cells forM. arthritidis. 11-day CFUs were unaffected by similar treatment.     

(R)-(Z,E)-9,11-octadecadien-13-olide: An intriguing lactone fromHeliconius pachinus (Lepidoptera)

Summary A fourteen-membered lactone,(R)-(Z,E)-9,11-octadecadien-13-olide, was isolated from extruded abdominal glands of a Neotropical, nymphalid butterfly,Heliconius pachinus (Lepidoptera). This compound was obtained from mature adults of both sexes, but was not detected in young adults or pupae.     

Retention ofB. burgdorferi pathogenicity and infectivity after multiple passages in a co-culture system

In vitro cultivation ofB. burgdorferi in BSK medium results in the loss of infectivity and pathogenicity after repeated passages. To prevent this loss, a feeder layer of tibio-tarsal joint tissue derived from newborn LEW/N rats was grown on Cytodex 3 microcarriers in ESG (formerly BSKE), a novel medium developed to support the growth of both the feeder layer andB. burgdorferi. A new pathogenic isolate (FNJ) and a high passage, non-pathogenic strain (TNJ) grew well in this co-culture system with high yields of viable organism. FNJ caused no growth inhibition or visible damage to the cells in the feeder layer. FNJ remained arthritogenic for newborn LEW/N rats after 22 passages in the co-culture system, but lost its arthritogenicity after 7 passages when cultured in BSK medium. This borrelia-mammalian tissue co-culture technique presents an experimental system to study the long term interactions ofB. burgdorferi with the infected host tissues in vitro, as well as facilitate diagnostic tests and vaccine development.This article forms New Jersey Agricultural Experiment Station paper no. D8420-19-92.     

Fungal competition and mycotoxin production on corn

Summary Aflatoxin and secalonic acid D production in corn in laboratory and field by mixed cultures ofPencillium oxalicum andAspergillus flavus orA. parasiticus was lower than production by the pure cultures. However, mixed culture of these molds withFusarium spp. did not affect mycotoxin production.     

Is ATP synthesized by a vacuolar-ATPase in the extremely halophilic bacteria?

The proton-dependent synthesis of ATP was demonstrated in representative members of the generaHalobacterium, Haloarcula, andHaloferax. In all cases, synthesis was not inhibited by nitrate or N-ethylmaleimide, inhibitors of the vacuolar-like ATPase found in Archaea, but was affected by azide, an inhibitor of F₀F₁-ATP syntheses. These observations extend the earlier observations withHalobacterium saccharovorum and suggest that ATP synthesis in these organisms is brought about by an F₀F₁-APT synthase.