Cyclic AMP level in red blood cells of Plasmodium berghei-infected Mastomys natalensis.

The present report describes the changes in cyclic AMP level which occur upon parasitization of red cells by Plasmodium berghei. Parasitized erythrocytes were separated from the non-parasitized population by percoll density-gradient centrifugation. An increase in the cyclic AMP content of both non-parasitized and parasitized erythrocytes of infected animals compared with that of uninfected animals was observed. The patterns of physiological response to isoproterenol in normal, parasitized and non-parasitized erythrocytes were identical.     

Suppression of chaos by periodic oscillations in a model for cyclic AMP signalling inDictyostelium cells

We investigate how the introduction of cells oscillating periodically affects the behaviour of a suspension ofDictyostelium discoideum amoebae undergoing chaotic oscillations of cyclic AMP. The analysis of a model indicates that a tiny proportion of periodic cells suffices to transform chaos into periodic oscillations in such suspensions. A similar result is obtained by forcing the aperiodic oscillations by a small-amplitude, periodic input of cyclic AMP. The results provide an explanation for the observation of regular oscillations in suspensions of a putatively chaotic mutant ofDictyostelium discoideum ¹². More generally, the results show how chaos in biological systems may disappear through the coupling with periodic oscillations.     

Inhibition of virus multiplication and alteration of cyclic AMP level in cell cultures by flavonoids

Summary The inhibitory effect of four flavonoid compounds on virus multiplication and their influence on the intracellular cyclic AMP (cAMP) level were studied in cell cultures. Quercetin and quercitrin reduced the yields ofHuman (alpha) herpesvirus 1 (HSV-1) andSuid (alpha) herpesvirus 1 (pseudorabies virus), but hesperidin and rutin had no effect. Further, quercetin and quercitrin elevated the intracellular level of cAMP, whereas hesperidin and rutin did not alter the cAMP level. Both antiviral activity and cAMP-enhancing effect were dependent on the concentrations of the flavonoids, and these effects turned out to be parallel.This study suggests that a relation exists between the antiviral effect and the cAMP-enhancing activity of flavonoids.     

Two classes of metabolites fromTheonella swinhoei are localized in distinct populations of bacterial symbionts

The marine spongeTheonella swinhoei (lithistid Family Theonellidae, Order Astrophorida) has yielded many important, bioactive natural products, most of which share structural features with bacterial natural products. The presence of microbial symbionts inT. swinhoei has been reported, and it was originally suggested that the cytotoxic macrolide swinholide A and many of the bioactive cyclic peptides fromT. swinhoei were all produced by symbiotic cyanobacteria. By transmission electron microscopy, we found four distinct cell populations to be consistently present inT. swinhoei: eukaryotic sponge cells, unicellular heterotrophic bacteria, unicellular cyanobacteria and filamentous heterotrophic bacteria. Purification and chemical analyses of each cell type showed the macrolide swinholide A to be limited to the mixed population of unicellular heterotrophic bacteria, and an anti-fungal cyclic peptide occurred only in the filamentous heterotrophic bacteria. Contrary to prior speculation, no major metabolites were located in the cyanobacteria or sponge cells.     

Isolation and characterization of hemagglutinins from the spongeDysidea herbacea

Summary The spongeDysidea herbacea (Keller) was found to possess hemagglutinins. The major component, DHA-I, is a protein with a mol.wt of 26,000, which dissociates into subunits of equal size (14,000). It contains large amounts of glutamic acid and aspartic acid residues, but no half-cystine, methionine or histidine residues. DHA-I reacted with rabbit and human AB0 erythrocytes. D-galactose and lactose were effective inhibitors of DHA-I. The sponge also contained a minor component(s) which reacted preferentially with rabbit erythrocytes but not with human AB0 erythrocytes.Acknowledgment. We thank Dr. M. Yamazaki, Faculty of Pharmaceutical Sciences, Teikyo University, for testing mitogenic activity ofDysidea agglutinins. This study was partly supported by a grant-in-aid for Overseas Scientific Survey from the Ministry of Education, Science and Culture, Japan.     

Cortinarins inCortinarius speciosissimus? A critical revision

Summary Fluorescent cyclic decapeptides, the so-called cortinarins, have been claimed to cause the toxicity of the deadly poisonous mushroomCortinarius speciosissimus. As the structure elucidation described in the literature is doubtful in decisive parts, the proposed structures must be disputed. The present study demonstrates that the fluorescence is mainly due to ergosta-4,6,8 (14),22-tetraen-3-one (8) and to photodecomposition products of the nephrotoxin orellanine (1). Moreover, we were not able to reproduce the isolation of fluorescent or any other cyclic peptides related to cortinarins fromC. speciosissimus, by various methods.     

Increased urinary excretion of cyclic nucleotides in X-linked hypophosphatemic (Hyp) mice

Summary Hyp mice, a model for human X-linked hypophosphatemia, had elevated urinary cyclic AMP, cyclic GMP, and magnesium excretion compared to normal mice. The data suggest a renal origin of the urinary cyclic nucleotides. No significant differences in plasma cyclic AMP and cyclic GMP were observed between genotypes.This work was supported in part by research grants from The Kroc Foundation and the NIH, RR-09016.     

Hormone and forskolin-stimulated cyclic AMP accumulation in human lymphocytes: reliability of longitudinal time measurements

Summary Reliability of measurement of lymphocyte cyclic AMP synthesis in intact cells was estimated by taking 3 successive blood samples during a one-month period from 11 healthy volunteers. Isoproterenol and prostaglandin E₁-stimulated cyclic AMP accumulation were used to evaluate the activity of these two receptor activities in human lymphocytes. Forskolin-stimulated cyclic AMP accumulation was used to evaluate the activity of the Ns/catalytic subunit. Only for forskolin was significant reliability observed. For isoproterenol and prostaglandin E₁ significant reliability was observed only for male subjects.Acknowledgment. This work was supported in part by the following organizations: Chief Scientist's Office, Israel Ministry of Health; Herman Goldman Foundation, New York; United Jewish Endowment Fund of Greater Washington-Pollinger Foundation.     

Role of adenosine A1 and A2 receptors in the regulation of aldosterone production in rat adrenal glands

Summary To investigate the roles of adenosine A₁ and A₂ receptors in the regulation of aldosterone production, we examined the effects of adenosine and adenosine agonists (N⁶-cyclohexyl adenosine; selective adenosine A₁ receptor agonist and 5-N-ethylcarboxamine adenosine; selective adenosine A₂ receptor agonist) on aldosterone and cyclic AMP production in rat adrenal capsular cells. Neither adenosine nor 5-N-ethylcarboxamine adenosine caused significant effects on basal aldosterone or cyclic AMP production. Also, adenosine (10^–3M) showed no consistent effects on aldosterone and cyclic AMP production induced by ACTH. On the other hand, N⁶-cyclohexyl adenosine exhibited a significant inhibition of basal aldosterone and cyclic AMP production at doses of 10^–4 M and 10^–3 M; furthermore, 10^–3 M N⁶-cyclohexyl adenosine inhibited aldosterone and cyclic AMP production stimulated by ACTH. These results suggest that adenosine A₁ receptors are coupled to and inhibit adenylate cyclase and may be involved in the inhibition of aldosterone production.     

Transgenic and mutant animal models to study mechanism of protection of red cell genetic defects against malaria

Malaria, caused by members of the genusPlasmodia, is still the most prevalent parasitic disease in the world. In an attempt to understand genetic factors conferring resistance to malaria, mouse models of thalassemia, sickle trait, and ankyrin and spectrin deficiency were studied during infection with species of malaria infectious to rodents. Although growth ofP. falciparum is not inhibited in thalassemic erythrocytes in culture, mice carrying a -thalassemia mutation were protected fromPlasmodium chabaudi adami, supporting epidemiologic findings. Transgenic mice expressing ^s hemoglobin were also significantly protected from two species of rodent malaria. Importantly, a significant role for the spleen in protection in the ^s transgenic mice was found. Finally, mice deficient in spectrin and ankyrin were studied with respect to their ability to support the growth of malaria. It was found that spectrin deficient mice were almost completely refractory toP. chabaudi adami andP. berghei. These models will allow further study of host factors in resistance to malaria.     

Inverse regulation of spore germination and growth by cyclic AMP inStreptomyces hygroscopicus

Summary The cyclic AMP level in germinating spores ofStreptomyces hygroscopicus rises to a maximum at outgrowth of germ tubes. Exogenous cyclic AMP results in an inverse effect on germination speed and growth.     

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.     

Agglutinins from aquatic insects—tumor cell agglutination activity

Agglutinins were identified in whole body extracts of aquatic insects by means of murine tumor cell agglutination, using sarcoma 180 ascites, Ehrlich, and MM-46 cells. Screening revealed agglutinins in 5 of 10 of the larvae tested, and in 2 of 6 of the water-dwelling adult insects;Gerris paludum insularis andGyrinus japonicus. Only the agglutinin from adultG. paludum also agglutinated human erythrocytes. An ascites tumor was converted into a solid form in vivo after administration ofG. paludum agglutinin. The observation that these aquatic insect agglutinins preferentially agglutinate tumor cells has considerable implications in terms of anti-tumor effects such as inhibition of cell proliferation and metastasis.Deceased.     

Fecundity of the blood-feeding insectRhodnius prolixus increases in successive periods of egg production

The fecundity of the blood-feeding insect,Rhodnius prolixus, was observed to increase in successive periods of egg production, each period being triggered by a single large blood meal. As previously published, the fecundity of mated animals was significantly higher than that of unmated animals for the first period of egg production. For a second period of egg production, fecundity increased significantly in both mated and unmated animals. By the fourth period, fecundity had returned to first-feed values for mated animals, but remained high for unmated animals, and the fecundity of mated and unmated animals was not significantly different. Thus, during successive periods of egg production, the processes which maintain fecundity of unmated animals below that of mated animals are overcome.     

Macrobiotus pseudohufelandi Iharos as a model for cytotaxonomic study in populations of eutardigrades (Tardigrada)

Summary The morphotype, chromosome number and Feulgen-DNA content of bisexual and unisexual populations ofMacrobiotus pseudohufelandi were examined. Individuals of unisexual populations were triploid with ameiotic parthenogenesis. Their lowest Feulgen-DNA content is about three-fold that of sperm from a bisexual population. Egg shell shape also differs in the two types of population. However, the highest Feulgen-DNA content was the same (24 A.U.) in both diploid and triploid animals.Study funded by MPI grant.     

Rapid effects of insulin on cyclic GMP location in an intact protozoan

We studied rapid changes in location of cyclic GMP inTetrahymena pyriformis. Insulin caused cGMP localization in cilia and near the plasma membrane (0.5–1 min). Later (1–5 min) cGMP localization was diffuse in cytoplasm with perinuclear accentuation. Inactive insulin analogs did not elicit these changes.     

Karyotypic races of the common shrew (Sorex araneus L.) from northern Poland

Summary Karyotypic races of the common shrew which differed with respect to the combinations of chromosome arms in certain 2-armed autosomes were distinguished in Poland. Two eastern races with the arm combinationik, and one western race with the arm combinationhi in the third pair of autosomes were established. In the contact area of these chromosomal forms, the fourth karyotypic race with the arm combinationhk was found.I wish to express my gratitude to my wife, A.M. Wójcik, M. Sc., for her help in catching the animals and making chromosome preparations. I must also offer my thanks to Dr J. Zima for giving me access to his as yet unpublished data, and to Prof. Z. Pucek and Dr S. Fedyk for reading the first draft of this paper.     

Thiarubrine A,a bioactive constituent ofAspilia (Asteraceae) consumed by wild chimpanzees

Summary Two African species ofAspilia (Asteraceae), which are used medicinally by man and which are eaten by wild chimpanzees in an unusual manner, were found to contain the potent antibiotic thiarubrine A as a major leaf phytochemical. Its presence in leaf material strengthens the view that the feeding behavior of wild chimpanzees is related to special physiological or pharmacological effects on the animals.