摘要:

ABSTRACT.The fine structure, elastic properties, and distribution of the fibrous, meshlike cement (bioadhesive) were studied for the test of the antarctic agglutinated foraminiferanAstrammina rara.Grain‐size analysis of particles incorporated into the test compared with adjacent sediment indicates thatA. rarais grain‐size selective. Fractured tests curl inward, suggesting that the test is under tension—an impression substantiated by micromanipulation observations. Changes in test appearance were examined by scanning electron microscopy after sequential chemical treatments combined with ultrasonication. Organic fibrils securing fine‐grained particulates on the test exterior were removed during initial sonication. A veil of fibrous organic material lining the test interior (i.e. inner organic lining) was removed by treatment with a nonionic detergent, revealing ligamentous cables of bioadhesive securely joining large grains. These cables are partially disrupted by treatment with sodium dodecyl sulfate, and further disrupted by disulfide reducing agents, suggesting that protein is an integral adhesive component. The large detrital grains incorporated into the test are arranged in an interlocked, optimally packed fashion. Together, these observations indicate that the seemingly simple spherical architecture ofA. rara'stest is in fact quite complex, consisting of large grains compressed by tensile cables of a proteinaceous bioadhesive, with additional rigidity supplied by fine particulate “mortar” deposited

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04891.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.Using the polymerase chain reaction and arbitrarily selected oligonucleotide primers of 10 or 11 bases, we have amplified DNA sequences fromTrypanosoma vivaxparasites isolated from South America and Africa. On the basis of polymorphisms in the DNA fingerprints generated by three of the primers, the parasites could be separated into two major groups, one comprisingT. vivaxisolates from Kenya and the second including all the otherT. vivaxparasites (from Colombia, The Gambia, Nigeria and Uganda). One of these three primers (ILo 525) also gave isolate‐specific DNA fingerprints for the parasites for the parasites tested, which will allow the use of this technique both in the species identification and discrimination ofT. vivaxparasite

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04892.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.Nosema scripta(Microsporida: Nosematidae), a new species of microsporidian parasite, is described from the cottonwood leaf beetle,Chrysomela scriptaF. (Coleoptera: Chrysomelidae), in North America. Studies using light and electron microscopy reveal that this species completes its life cycle in direct contact with the cytoplasm of cells within the fat body, midgut, hindgut, muscles, central nerve cord, Malpighian tubules, tracheal end cells, and ovaries. the microsporidium is monomorphic, all life stages are diplokaryotic, and spores develop from disporous sporonts. The mature spores are broadly oval and measure 4.2 ± 0.10 times 3.4 ± 0.04 μm. Spores contain a tubular polar filament that is arranged peripherally in a single layer of 13‐15 coils. Both horizontal transmission and vertical transmission have been demonstrated for this microsporidium inC. scriptain the laboratory. The Colorado potato beetle,Leptinotarsa decemlineata(Say), was susceptible to infection with this pathogen in cross‐infectivity s

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04893.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.A large, uni‐ or multinucleate vampyrellid rhizopod,Lateromyxa gallican. g., n. sp., has been isolated several times from two lakes in central France between September 1973 and August 1989 and cultivated for several months or years under laboratory conditions. No essential variations of feeding behaviour were found over the time; all isolated strains invade the trichomes of the green algaOedogoniumand move, divide and encyst inside the vanished plant cells. Penetration is performed by attacking the cross walls and only primary attacks are directed against the lateral cell walls of the algae. These findings contrast with the behaviour, life cycles and fine structure of all known species of the generaVampyrella, Hyalodiscus, ArachnulaandGobiella.The establishment of a new genus,Lateromyxa, with the type speciesLateromyxa gallicais therefore propose

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04894.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.The effect of low incubation temperature on synchronized cultures ofPlasmodium falciparumwas studied. Young trophozoites that were maintained at 28°C matured slowly and invaded poorly. Growth seemed to arrest when parasites reached a maturation equivalent to 30 h, although they reestablished their growth normally when returned to 37°C. On the other hand, 36‐h synchronized parasites that were transferred to 28°C completed their cell cycle with a 12‐16 h delay, but without changes in the parasite as seen by light microscopy and without a diminution in the efficiency of the invasion or in the incorporation of35S‐methionine. These results might be useful for obtaining parasites at defined stages of development at the desi

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04895.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.RPMI‐1640 is routinely used as the basal medium for the in vitro maintenance of malaria parasites. In this study we tested several commercially available nutritional media in aPlasmodium chabaudi chabaudierythrocyte invasion assay and showed that three media, BME Basal Medium—modified, Dulbecco's Modified Eagle Medium, and William's Medium E, improved the level of merozoite invasion when compared with RPMI‐1640. These media improve the rate of maturation of newly invaded rings to young trophozoites. Radioisotope incorporation by trophozoites maintained in these three media was also improved when compared to trophozoites maintained in RPMI‐1640. BME Basal Medium—modified, or a combination of three parts BME Basal Medium—modified with one part William's Medium E, supported higher levels of erythrocyte invasion by merozoites. We suggest that either of these media replace the currently used RPMI‐1640 for in vitro studies onP

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04896.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.We observed different low salinity tolerances between two groups of populations ofEuplotes crassus.After mating analysis, the less tolerant populations could be assigned to three mating groups. Two of them were separated by preconjugative barriers but both conjugated with a third one. A breeding test showed evidence of (potential) introgression mediated by this “bridging” group. On the other hand, the more tolerant populations formed a fourth mating group unable to conjugate with the others and characterized by distinct zymogram patterns. We conclude that natural introgression among the studied populations is not complete and that the species structure ofE. crassuscomprises intrafertile sets of populations among which gene flow may be difficult or virtually abs

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04897.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.Urosporidium cannonin. sp. was found in most tissues of a polyclad turbellarian associated with commercial oyster farms from eastern Moreton Bay, Australia. Mature spores had 11 to 13 episporal tails at irregular intervals around the spore wall. The spherule, prominent in development, dispersed as the spores matured. Spores were found within cysts that contained up to a few hundred spores at the same stage of development. Mature cysts occurred in groups and their masses of dark, golden spores resulted in black patches on the otherwise red‐brown turbellarian. The infection may have commercial importanc

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04898.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.The peroxisomes of the parasitic ciliateIchthyophthirius multifiliiswere studied, using ultrastructural and cytochemical techniques. In this ciliate most peroxisomes possess a circular or oval section less than 0.6 μm in diameter. However, some dumbbell‐shaped and elongated peroxisomes could also be observed. These organelles were frequently associated with the mitochondria and were more abundant in the cell cortex than in the center of the ciliate. Small vesicles and dense nucleoids were usually present in the ultrathin sections of these peroxisomes. Peroxisomal vesicles and tubular structures were selectively impregnated with osmium tetroxide. Catalase was detected by cytochemical techniques inI. multifiliisperoxisom

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04899.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT.A new heterotrophic flagellate has been discovered from sites in Maryland, Michigan and Wyoming. The flagellate resides within a lorica constructed of a meshwork of intertwined fibrils with the outer surface invested with nail‐shaped spines. The organism “reclines” within the lorica with its ventral aspect directed upward, and has two heterodynamic flagella, neither of which bears mastigonemes. One flagellum is directed upward and the other is arched over the ventral aspect of the body. Ingestion of bacteria takes place at the left posterior half of the cell. The organism is anchored to the lorica on the right posterior side by a series of regularly spaced cytoplasmic bridges and at the left anterior of the cell by a cytoplasmic appendage similar to the “languette cytoplasmique” found in some bicosoecids. The right side of the cell is raised into a flattened lip with the outer margin reinforced by a ribbon of microtubules. The new flagellate has mitochondria with tubular cristae and lacks a Golgi. A new genus is created to accommodate both the new flagellate described herein andHistiona campanulaPenard. A new family is proposed to include the new genus an

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1993.tb04900.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY