Effect of actinomycin D on Trypanosoma cruzi

Viable metacyclic forms of T. cruzi, Y strain, treated with an adequate dose of actinomycin D (50 micrograms Act-D/ml/10(7) parasites/ml for 72 h at 28 degrees C) showed the following properties: 1) they lost their ability to replicate in culture medium, in blood and in tissues of normal mice and were no longer able to incorporate tritiated thymidine; 2) they could not penetrate into Vero cells and could not replicate inside normal macrophages; 3) they retained their immunogenicity and the ability to protect mice against a virulent infection; 4) they did not induce histological lesions as described in chronic experimental Chagas' disease.     

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.     

Evidence for a role of IFN γ in control ofListeria monocytogenes in T cell deficient mice

Summary The role of interferon (IFN) in controlling chronic infections ofListeria monocytogenes (Listeria) was studied in athymic C57BL/6nu/nu mice, and by treating thymectomized C57BL/6 +/+ mice with monoclonal rat CD4 and CD8-specific monoclonal antibodies (Mab). Mice treated with a combination of the two T cell subset antibodies were similar to athymic, nude mice in being able to contol Listeria infection, keeping the titers below 3–5 log₁₀ bacteria per organ, but they could not eliminate them completely. Treatment with antibodies to IFN of nude or CD4⁺ + CD8⁺-T cell-depleted mice suffering from chronic Listeria infection caused a marked increase of Listeria titers, in liver and spleen. This result implies a role of IFN in maintaining anti-Listeria resistance in mice lacking mature T cells.     

Control of obesity inA vy /a mice by 5α-androstan-17-one

Summary Treating VY/WfL-A ^vy /a mice with 5-androstan-17-one, a mammalian glucose-6-phosphate dehydrogenase inhibitor, prevented the mice from becoming obese. The weight difference between treated and controlA ^vy /a mice was mainly due to a decreased accumulation of triacylglycerol. The compound did not suppress appetite, had no detectable toxicity and did not affect the lipogenesis rates in the liver and carcass. The weight-controlling effect of 5-androstan-17-one inA ^vy /a mice was reversible upon withdrawal of treatment.The authors wish to thank Mr W.R. Gibson and Drs C.G. Culbertson and P.N. Harris for performing the pathological examinations.     

2-Carboxyethylgermanium sesquioxide,a synthetic organogermanium compound,as an inducer of contrasuppressor T cells

2-Carboxyethylgermanium sesquioxide (Ge-132), a synthesized organogermanium compound with immunomodulaing activities, was shown to be an inducer of anti-suppressor T cells in normal mice. The suppressor cell activity of T6S cells, a clone of burn-induced CD8⁺ IL-4-producing suppressor T cells, was clearly inhibited when a mixed lymphocyte-tumor cell reaction of the clone was conducted with splenic mononuclear cells from mice treated orally with a 100 mg/kg dose of Ge-132. The activity of anti-suppressor cells was demonstrated in spleens of mice 2 days after treatment with Ge-132 and reached its peak on day 3. The anti-suppressor cells induced by the compound were of a contrasuppressor T cell-linage, because they were characterized as CD4⁺ CD28⁺ TCR/⁺ Vicia villosa lectin-adherent T cells. These cells produced IFN- but did not produce IL-2, IL-4, IL-6 or IL-10 in their culture fluids. CD4⁺ anti-suppressor T cells induced by Ge-132 may be different from other subsets of CD4⁺ T cells because Th1 and Th2 cells generated in our laboratory did not adhere toVicia villosa lectin-coated petri dishes, and each produced specific cytokines. Th1 cells produced IFN- and IL-2 while Th2 cells produce IL-4 and IL-10 in vitro. These results suggest that Ge-132 may be useful as an inducer of contrasuppressor T cells in immunocompromised individuals bearing suppressor T cells. To eliminate suppressor T cells from immunocompromised hosts may result in improved resistance from various opportunistic infections.     

Insect hormones in vertebrates: Anabolic effects of 20-hydroxyecdysone in Japanese quail

Ecdysteroids are hormones controlling cell proliferation, growth and the developmental cycles of insects and other invertebrates¹. They are occasionally present in various unrelated plants for no apparent reason; no phytohormonal function has yet been identified. In certain cases, ecdysteroids are accumulated to high levels in leaves, roots or seeds. Some ecdysteroid-containing plants have been known as medicinal plants for centuries. One of them,Leuzea carthamoides Iljin (Asteraceae), growing in Central Asia, contains 0.4% ecdysteroid in dry roots and 2% in seeds. A pharmacological preparation from this plant, Ecdisten, is already available as a commercial preparation for its anabolic, tonic and other effects, for medical use (review²). It remained problematic, however, whether ecdysteroids were truly responsible for these effects, becauseLeuzea contains a number of other biologically active compounds in addition to ecdysteroids. We extracted and purified ecdysteroids from the seeds ofLeuzea. With 6 g of 96% 20-hydroxyecdysone (20E), we made a large-scale feeding assay with Japanese quail to find out whether ecdysteroid alone could duplicate the anabolic effects of the seeds. We found that the 96% ecdysteroid increased the mass of the developing quails in a dose-dependent manner, with the rate of increase proportional to the ecdysteroid content in the seeds; there was a 115% increase in living mass with 100 mg kg^–1 of pure 20E compared with 109.5% increase with 100–180 mg kg^–1 20E equivalents in the seeds. We conclude that the plethora of growth-promoting, vitamin-like effects induced in vertebrates byLeuzea is mediated by ecdysteroids.     

In vitro inactivation of corpora allata of the bugOncopeltus fasciatus by precocene II

Summary Corpora allata fromOncopeltus fasciatus incubated in vitro in medium containing 10^–5.35 M (1 g/ml) of precocene II lose their ability to secrete juvenile hormone when reimplanted into last instar larvae.Acknowledgments. We thank Mr K. Dorn, Mrs L. Dolezal, Mrs V. Nötzli-Graf, Mr K.H. Trautmann and Mr A. Schuler for technical help, Dr W. Vogel and Dr A. Dübendorfer for valuable discussions.     

Volatiles from clover headHypera meles (Fab.) and alfalfaH. postica (Gyllenhal) weevils: search for pheromones

Summary Volatile fractions of the clover head,Hypera meles (Fab.), and alfalfa,Hypera postica (Gyllenhal), weevils contained three of four boll weevil,Anthonomus grandis (Boh.), pheromone components, (Z)-3,3-dimethylcyclohexane ^1,-ethanol and (Z)- and (E)-3,3-dimethylcyclohexane-^1,-acetaldehyde. Also found were eight oxygenated monoterpenes, previously identified as precursors and intermediates of the boll weevil pheromones.     

Individual recognition and incest avoidance in eusocial common mole-rats rather than reproductive suppression by parents

Non-reproductive females in families of eusocial common mole-rats (Cryptomys sp., Rodentia) are not suppressed by their mother, (either behaviourally or pheromonally) as is generally assumed. They do not mate with their father and brothers simply because they are not sexually attractive for them (and vice versa). The incest avoidance is based on the capability to recognize (and keep in memory for up to three weeks) each family member individually. A sterile daughter may conceive and deliver young in her parental family if given the opportunity to mate with an unfamiliar mate in a separate cage. In this way, two females may breed side by side in one family.     

Chromate reduction inStreptomyces

Summary Streptomyces species 3M grew in peptone yeast extract medium with 1000 g/ml K₂Cr₂O₇. Incubation of the chromate with different cell fractions in the presence of NADH and NADPH resulted in a decrease of Cr⁶⁺ in the reaction mixture. The level of Cr⁶⁺ was reduced by 82.7% by a particulate cell fraction obtained by centrifugation at 105,000×g for 1 h, in the presence of NADH. The reducing enzyme was associated with this cell fraction. The enzyme was constitutive and reduced Cr⁶⁺ to Cr³⁺.     

Selection for class IIMhc heterozygosity by parasites in subterranean mole rats

Mhc organization and polymorphism have previously been studied²⁶ in the four chromosomal species of theSpalax ehrenbergi superspecies in Israel, serologically, and at the DNA, RFLP and sequence levels of class I and class II genes. Here we demonstrate that the observed heterozygosity ofMhc class II genesP₁ with 11 alleles, andQ, with at least 14 alleles, is positively and significantly correlated with infectivities of ectoparasites (gamasid mites)¹⁷ and endoparasites (helminths)¹⁸.Mhc heterozygosity is highest in the most infected area, which is in the most humid-warm region of the superspecies range, or where two zoogeographic regions overlap. We conclude that the evolutionary forces responsible for theMhc class II two-gene polymorphisms include selection for increased heterozygosity as a defense strategy against ecto- and endoparasite infections.     

Strong mutagenic action of a bipyridylium herbicide in a N2-fixing blue-green alga

Summary The herbicide paraquat (1,1-dimethyl-4,4-bipyridylium ion) has been found to exert a growth inhibitory effect on the N₂-fixing blue-green algaNostoc muscorum in nitrogen-free (N₂) and NO ₃ ^– media, without any apparent inhibitory or stimulatory effect on the heterocyst-forming capacity of the organism. With a dose of paraquat permitting about 20 and 50% survival of this alga a reverse mutation (fromhet ⁺ nif ^– auxotrophy tohet ⁺ nif ⁺ prototrophy), a forward mutation (for L-methionine-DL-sulfoximine [MSO]-resistance), and an auxotrophic mutation (for carbon-auxotrophy through methylamine [MA]-resistance) have been obtained. The toxic and mutagenic effects of this agrochemical have been compared with those of the well known mutagen MNNG (N-methyl-N-nitro-N-nitrosoguanidine) and found to be stronger than those of the latter in each case.The author wishes to thank Mr Girish Nath, Lakshami Chemicals Pvt. Ltd., Phatuha (Patna), India, for providing pure samples of the herbicide for the present investigation. The receipt of financial assistance for this work in the form of a Higher Research Associateship Award to the author from the University Grants Commission, Govt. of India, New Delhi-110002 (Grant No. F/16-51/83), is thankfully acknowledged.     

Insect tissues,not microorganisms,produce linoleic acid in the house cricket and the American cockroach

Summary Biosynthesis of linoleic acid, 182(n–6), was unambiguously demonstrated to occur in the cockroach,Periplaneta americana, and the cricket,Acheta domesticus. Axenic tissue from both of these insect species was demonstrated by radio-gas-liquid chromatography (radio-GLC) and radio-high-performance liquid chromatography (radio-HPLC) to incorporate [1-¹⁴C]acetate and [1-¹⁴C]oleate into this essential fatty acid.This work was supported by the National Science Foundation under grant DCB-8914417. We would like to thank Coby Schal for his generous gift of American cockroaches and Tania Kellermeyer for her excellent technical assistance.     

Differential expression and dosage compensation of theα-amylase gene inDrosphila miranda

Summary The-amylase gene ofDrosophila miranda is located on the X²-and on the neo-Y-chromosome, both developing sex chromosomes. Crosses between strains carrying different electrophoretically distinguishable alleles of the-amylase gene were performed. Females of the F₁ offspring showed the expected heterozygosity, while the males proved to be hemizygous for this locus. Only the gene on the X²-chromosome is expressed, whereas the corresponding gene on the neo-Y-chromosome is not. Estimates of the-amylase activity in crude homogenates of male and female flies suggest strongly that the-amylase gene is dosage compensated inD. miranda. In contrast to this situation, in all otherDrosophila species the-amylase allele is autosomal and hence not dosage compensated.Acknowledgments. We would like to thank Betty C. Moore, for the kind supply ofD. miranda strains. For the help and advice in the electrophoretic separation of the-amylase variants we are indebted to Dr W. Pinsker. This work was supported by a grant from the Fonds zur Förderung der wissenschaftlichen Forschung, P5413 (Austria).     

The partitioning ofΔ 1-tetrahydrocannabinol into erythrocyte membranes in vivo and its effect on membrane fluidity1into erythrocyte membranes in vivo and its effect on membrane fluidity1

Summary ¹-Tetrahydrocannabinol ( ¹-THC) has been quantified directly in erythrocyte membranes from drug-treated mice using gas chromatography/mass spectrometry. Concentrations of approximately 6 ng ¹-THC/mg membrane protein (10^–5 M) were found when effects of the drug on behavior were prevalent. At these concentrations the drug produced a decrease in membrane order as measured by ESR.This work was supported by grants from the Medical Research Council, the Wellcome Trust and the E. P. Abraham Cephalosporin Trust     

The Dead Sea — alive again

In the thirteen years of quantitative studies on the microbiology of the Dead Sea from 1980 onwards three distinct periods can be discerned. Mass development of the green unicellular algaDunaliella parva (up to 8,800 cells/ml) and red archaeobacteria (2×10⁷ cells/ml) was observed in 1980, following a dilution of the upper water layers by rain floods. This bloom disappeared at the end of 1982 as a result of a complete mixing of the water column. During the period 1983–1991 the lake was holomictic, and noDunaliella cells were observed. Viable bacteria were present during this period in very low numbers. Heavy rain floods during the winter of 1991–1992 caused a new stratification as the upper five meters of the water column became diluted to 70% of their normal salinity. In this upper water layerDunaliella reappeared (up to 3×10⁴ cells/ml at the beginning of May, rapidly declining to less than 40 cells/ml at the end of July), and a bloom of red archaeobacteria (3×10⁷ cells/ml) once more imparted a red coloration to the lake.     

Unusual antimicrobial compounds fromAeollanthus buchnerianus

Using bioassay guided isolation, three novel 12 carbon polyoxygenated fatty acids and a novel abietane diterpene have been isolated from the the chloroform extract of aerial parts ofAeollanthus buchnerianus (Lamiaceae). Rigorous spectroscopic methods were used for compound identification. (Z,Z)-8-acetoxy-5-hydroxydodeca-2,6-dienoic acid and (Z,Z)-5,8-dihydroxydodeca-2,6-dienoic acid inhibited the spore germination ofCladosporium cucumerinum (both with Minimum Inhibitory Dose (MID) values of 1 g) andAspergillus niger (MID 5 and 25 g respectively). Further, they also reduced the hyphal growth ofPythium ultimum. (Z)-5-hydroxy-6,7,8-triacetoxydodeca-2-dienoic acid exhibited short term inhibition of the growth ofCladosporium cucumerinum. The novel abietane diterpenoid, (rel)-14-acetoxyabiet-7-en-18-oic acid inhibited the growth of the gram positive bacteriaBacillus subtilis, staphylococcus aureus andStreptomyces scabies (MIC values 80, 20 and 20 g ml^–1 respectively).     

Weak static magnetic fields increase the speed of circumnutation in cucumber (Cucumis sativus L.) tendrils

Tendrils are thread-like organs whose function is to support the stems of many species of climbing plants. Tendrils naturally move (circumnutate) in space. Individual tendrils of cucumber (Cucumis sativus L.) Poinset had the vertical component of their mean velocity vector of circumnutation changed when exposed to a range of weak static magnetic fields between 1 and 16 mT. The speed (modulus) of the velocity vector was significantly increased (p=0.016) in the vicinity of a magnet, but its direction did not show a definite trend with respect to the magnet. Although cucumber tendrils bear static positive charges, they did not behave as charged bodies do in a magnetic field, neither did they show a magnetotropic response. In fact, tendrils showed a nastic response to magnetism. Magnetic fields affected some processes underlying the movement of circumnutation, but no clear interpretation of them can be given presently on the basis of the known effects of magnetism on plants. It is clear that cucumber tendrils, because of some inherent susceptibility to magnetism or their particular size and shape, are very sensitive to relatively low static magnetic field strengths.     

Partial purification and characterization of acid phosphatase from sporulated oocysts ofEimeria tenella

Summary Acid phosphatase ofEimeria tenella oocysts (Peak II) was purified 77-fold with a recovery of 26% using protamine sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-200 gel filtration. This enzyme occurs in multiple forms as indicated by two peaks which can be separated by DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. The partially purified enzyme has optimal activity at pH 4.5. With p-nitrophenyl phosphate the Km and V_max values for (Peak II) were 25 mM and 1.57 mol/min/mg protein, respectively. The enzyme (Peak II) ist strongly inhibited by Hg⁺⁺, Cu⁺⁺, iodoacetamide, fluoride and molybdate. Tartrate and other divalent metal ions have no effect on enzyme activity. The partially purified Peak II phosphatase is not a glycoprotein as it is not absorbed on concanavalin-A Sepharose and its treatment with bacterial neuraminidase does not alter its elution profile through DEAE cellulose.     

ATP-dependent Ca++-Extrusion from human red cells

Zusammenfassung In einer Lösung mit 1,39M/ml Ca⁺⁺ waren rekonstituierte menschliche Erythrozyten im Stande, ihren ursprünglichen Ca-Gehalt von 2,39M/ml Zellen in 60 min bei 37 °C auf 0,46M/ml Zellen zu senken, sofern sie Mg-ATPat enthielten. Dieser aktive Transport war durch g-Strophanthin nicht hemmbar, konnte aber mit 5 · 10^–4 M Salyrgan unterdrückt werden.