ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02872.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTA reliable method for producing reproductive cysts inTetrahymena patulais described. The procedure involves the isolation of macrostomes without cytopharyngeal pouches in microdrops of distilled water under oil. The study of silver‐impregnated specimens has shown that a complex pattern of oral resorption and reformation occurs within the cyst that leads to the formation of a group of small cells with recessed oral apparatuses. These cells, called “cryptostomes,” swim very rapidly on excystment and are incapable of either feeding or reproducing. They are presumably dispersal forms. Oral morphogenesis during the transformation of excysted cryptostomes into microstomes and macrostomes is also desc

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02873.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTCrypthecodinium cohnii, a small marine heterotrophic homothallic dinoflagellate, has diversified into a complex of morphologically very similar breeding groups (biological species or sibling species), some of which have become widely dispersed. Membership of two clones in the same sibling species is shown by their sexual compatibility as determined by genetic complementation in zygotes formed from motility mutants derived from the two stocks. Membership in different sibling species may be inferrec when motility mutants of one strain do not complement those of another. Fifty‐six clones representing seaweed enrichments from *** geographic sites have been found to belong to 28 sibling species; 35 clones are members of seven wide‐ranging biological species, and 21 are single representatives of 21 other breeding groups within the ranges of the others. Of 174 clonal isolates in our possession, 168 conform in size and shape toC. cohnii.Six others which have smaller cells and only one‐fifth the standard DNA and chromosome number belong, we believe, to another species. TheC. cohniicomplex provides a unique opportunity for the study of evolutionary divergence and geographical dispersion of a dinoflage

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02874.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTWith the aid of energy‐dispersive X‐ray microanalysis, several protozoa were tested for content of cations within inorganic minerals. The skeleton of acantharia consists mainly of Sr with small quantities of Ca and Ba. TwoLoxodesspecies contain nothing but Ba, while in someRemanellaspecies Sr with small quantities of Ba were present. In oneGeleiaspecies, Ca with small quantities of Sr was found; in twoTrachelocercaspecies from Sylt (Germany), Ba is there in addition. AnotherTrachelocercaspecies from northern Italy lacked Ba, but did possess Mn. InProrodononly Ca was fo

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02875.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTCiliophrys marinais a small marine helioflagellate, with a central nucleus, which is capable of reversibly transforming from a rapidly swimming flagellate cell with no axopodia to the structure of a heliozoan with a flagellum that beats only a few times a minute. When in the flagellate form, the flagellum acts as a tractellum due to the tubular mastigonemes found along its length. When the rapidly swimming flagellate strikes a piece of debris, the flagellum goes through a very characteristic shock‐induced avoidance reaction. Similarly, when a mechanical shock is delivered to the cell in its heliozoan form, the axopodia are contracted in less than 20 msec. Both reactions are inhibited in low calcium seawater. Transformation from the heliozoan to the flagellate form is accomplished by slow retraction and absorbance of the axopodia and activation of the flagellum. Ultrastructurally, each axopodium is found to contain three microtubules which attach to the outer nuclear membrane of the central nucleus at sites that this study characterizes by electron microscopy of thin sections and freeze fracture preparations. The mitochondria have tubular cristae, each containing an intracristal filament. Finally, a taxonomic review of the helioflagellates is presented, and it is suggested thatC. marinais derived from the chrysomonads. An argument is also made for classifyingC. marinawith the heliozoan order Actinophryida, as a recently published classification of the protozoa doe

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02876.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe reproduction ofBabesia ovisinside the ovary of the vector tickRhipicephalus bursawas studied by electron microscopy. The kinetes ofB. ovisinvade the ovary of the tick via hemolymph. The kinete, when situated intracellularly, is transformed into a polymorphous stage that loses all features of the invasive form. The nucleus elongates enormously and forms many folds which extend throughout the cell. Subsequently, the lobulated nucleus and the cytoplasm are divided into numerous uninuclear cytomeres by invaginations of the cell boundary and by interconnecting endoplasmic reticulum. Each cytomere, bounded by a unit‐membrane, measures ca. 4 μm in diameter and finally forms a new kinete. This proceeds as protrusion of the cytoplasm into an intracytoplasmic vacuole. An apical complex is initially visible at the tip of the protrusion that emerges steadily into the lumen of the expanding vacuole. The nucleus of each cytomere is incorporated into the newly formed kinete, which is surrounded by a coccidian pellicle the inner membranes of which are formed at the base of the intracellular protrusion. Nearly all of the cytoplasm is used for the differentiation of the kinete, which finally lies folded inside the vacuole. The kinete is apparently released by rupture of the vacuole. The description of this peculiar reproduction completes the knowledge of similar reproductive processes in other tissues of the tick. A comparison of the differentiation of the kinete inBabesiaand inTheileriaindicates a similar mode of developme

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02877.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTUntil recently, pansporoblastic microsporidia that produce a variable and large number of sporoblasts from a sporont have been included in a single genus, namelyPleistophoraGurley, 1893. Ultrastructural studies have been used to determine whether the resemblance of these species is fundamental or superficial. The results indicated that the multisporous pansporoblastic forms belong to at least three genera and, thus, thatPleistophorais a “composite genus.” The term pansporoblast was originally used for stages in myxosporidian development. The term sporophorous vesicle adopted from Gurley is suggested for the spore‐containing vesicle in the Microspora. Three species were studied:Pleistophora typicalis, the type‐species;Pleistophora culicis, for which a new genusVavraiahas already been proposed; andPleistophora simulii. P. typicalisandV. culicishave isolated nuclei throughout their development, and the sporophorous vesicle wall enveloping the sporoblasts is derived from amorphous secretions laid down during merogony external to the plasmalemma.PleistophoraandVavraiaare differentiated principally in terms of the structure of the sporophorous vesicle wall and mode of division of the sporogonial plasmodium. The nuclei of young sporonts ofP. simuliiare in diplokaryon arrangement and undergo meiosis to give haploid nuclei in the sporoblasts. The sporophorous vesicle wall is membranoid and is laid down external to the plasmalemma at the onset of sporogony. A new genus,Polydispyrenian. g., is suggested for this species, the affinities of which are closer to the dimorphic species of microsporidia than toPleistophoraorVavraia. The terms “merontogenetic sporophorous vesicle” and “sporontogenetic sporophorous vesicle” are used to distinguish between

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02878.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThin‐sectioning and freeze‐etching electron microscopy were applied to explore the structure and the temperature‐ and Ca2+‐response of the different host and parasite membranes during intraerythrocytic development ofPlasmodium knowlesiinMacacca mulatta. The plasma membrane of uninfected erythrocytes is temperature‐ and Ca2+‐responsive: chilling to 4°C and exposure to 5 mM Ca2+induces a slight decrease in IMP‐frequency and the emergence of small IMP‐devoid patches on P‐faces. On parasite infection, the erythrocyte membrane becomes modified as indicated by an enhanced temperature‐response and the appearance of caveolae, ca. 70–90 nm in diameter. The frequency of these caveolae is increased in schizont‐infected erythrocytes. Moreover, electron dense plaques, ca. 40 nm in width, appear just beneath the erythrocyte membrane in late trophozoites and schizonts, thus indicating a further modification of the host cell membrane during parasite development. The membrane of the parasitophorous vacuole, derived from the host plasma membrane, dramatically reduces the IMP‐frequency especially on the P‐face upon parasite infection. This leads to an apparent reversal of the IMP‐distribution persisting throughout the whole infection cycle. The parasite plasma membrane forms local compaction domains with the nuclear envelope in ca. 30% of the ring‐stages and trophozoites, which disappear in late trophozoites and schizonts. Moreover, the IMP‐frequency on plasma membrane fracture faces almost doubles during parasite development. Chilling induces a decrease in the IMP‐frequency on P‐faces of the plasma membrane. Surprisingly, however, the parasite plasma membrane and the vacuolar membrane respond to externally applied Ca2+with almost a doubling of the IMP‐frequency. The different parasite endomembranes also undergo characteri

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02879.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe structure of both the host and parasite membranes during stages in the asexual development ofPlasmodium chabaudiin mouse red blood cells is examined by transmission electron microscopy of thin sections and freeze‐fracture preparations. The erythrocyte's plasma membrane, the membrane of the parasitophorous vacuole, and the plasma membrane of the parasite exhibit different structural properties in terms of membrane width and the frequency and diameter of the typical intramembrane‐particles (IMP) populating the membrane's fracture faces. The difference between the parasitophorous vacuolar membrane and host cell's plasma membrane is remarkable because the vacuolar membrane is formed from an invagination of the erythrocyte's plasma membrane. The vacuolar membrane has significantly reduced frequencies and diameters of IMP's on both faces and reveals a marked temperature response manifesting itself as large IMP‐devoid domains emerging on both faces on chilling to 4°C. In contrast, cooling induces only some very small IMP‐devoid patches on both faces of the host plasma membrane. Neither of these membranes changes significantly as parasite development progresses. In contrast, the parasite's plasma membrane shows local alterations during its development, forming compaction domains with the nuclear envelope in ca. 30% of the ring‐stages and trophozoites. These compaction domains disappear in late uninuclear trophozoites and schizonts. Furthermore, the plasma membrane of the host cell, the vacuolar membrane, and the parasite's plasma membrane do not respond to externally applied Ca2+, and their temperature‐response remains unaltered during the infection cycle. Thus, modification of these three membranes as a consequence of invasion and development of the parasites, as recently found in the primate malaria caused byP. knowlesi, can be detected neither directly nor indirectly via temperature‐ and/or Ca2+‐response in the rodent malaria caus

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02880.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTLaboratory‐rearedFundulus grandisandF. heteroclituswere experimentally infected withEimeria funduliby being fedPalaemonetes pugio(grass shrimp) collected from endemic areas. Histological sections were made of heart, liver, hepatopancreas, spleen, gall bladder, kidney, intestine, peri‐intestinal fat, reproductive organs, and brain fromF. grandissacrificed at 1, 2, 6, 12, 18, and 24 h and fromF. heteroclitusat 5, 6, 9, 14, 19, 24, 29, 34, 39, and 44 days after consuming naturally infected shrimp. We first found merogonous stages at day 9 postinfection (p.i.). No developmental stages of the parasite could be positively identified in the tissues of experimentally infected fish prior to day 9 p.i. Mature meronts were found 14 days p.i. The majority contained 8–16 (mean, 13) merozoites, but a few meronts had 18–26 (22) merozoites. Gamonts first appeared on day 14, were mature by day 19, and fertilization was completed by day 24 p.i. After sporoblast formation, sporopodia appeared during sporocyst wall formation, between days 24 and 29 p.i. Sporozoite formation was completed by day 44 p.i. in most sporocysts. Most endogenous stages occurred in hepatocytes; however, pancreatic and spleen cells were sometimes infected with

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1982.tb02881.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY