摘要:

The effect of the microtubule inhibitor nocodazole was studied onParameciumand shown to arrest cell multiplication, depolymerize the internal microtubule network, and block the development of macro‐ and micronuclear spindles and of the cytospindle (a cortical microtubule array assembled during division). After ultraviolet mutagenesis, three mutants resistant to nocodazole, that is capable of continued growth in the presence of the drug, were isolated and shown to correspond to three nonallelic single‐gene nuclear mutations. One (nocr‐1) is semidominant while the other two (nocr‐2andnocr‐3) are recessive. Cytological and physiological studies of nocodazole's effects on the mutants demonstrate that their resistance is due neither to a lack of drug penetration nor to its degradation since, in each mutant in the presence of the drug, some microtubule networks are normal or subnormal while others remain affected as in wild‐type cells. These are the first mutants resistant to microtubule depolymerizing drugs obtained in ciliates that provide a new tool for studying the assembly and dynamics of the diverse microtubule arrays in this type

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01362.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The spore stage ofHaplosporidium nelsoni, the ascetosporan parasite causing multinucleated sphere unknown (MSX) disease in oysters,Crassostrea virginica, has been reported so rarely (≥0.01% of infected oysters) that a second host has been postulated. However, recent intensive sampling of young (≥1 year) oysters in Delaware Bay, U.S. suggests that spore formation occurs regularly in this group and that spores are produced in at least 75–85% of all infections reaching the advanced stage. Sporulation was seasonal, occurring over two to three weeks in late June/early July and again in late summer/early fall. Our data indicate that sporulation byH. nelsoniin oysters is more common than previously suspected, occurring in a segment of the host population that may not have been sufficiently sampled in the past, and that a direct life cycle should be reconsi

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01363.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

To facilitate studies of rDNA molecular genetics inTetrahymena thermophila, we attempted the detection of polymorphisms in the nontranscribed spacers (NTSs) using polymerase chain reaction (PCR), starting with minute amounts of DNA. The targeted polymorphic regions are 85% adenine‐thymine (AT). We found conditions of efficient and specific in vitro amplification of targeted segments in the replication domain of the 5′NTS and in the subtelomeric segment of the 3′NTS. The identity of the amplified segments was confirmed by restriction enzyme digestion and DNA sequence analysis. Digestion of the template DNA at restriction sites upstream and downstream of the targeted region increased the efficiency of amplification, presumably because the targeted segments are in a palindromic molecule. Starting from total cell DNA corresponding to as little as 0.03 picogram (equivalent to the DNA content of 0.003 cells or about 30 rDNA molecules), we observed the amplified band after agarose gel electrophoresis and ethidium bromide staining. The yield indicated more than 10‐billion‐fold amplification. Amplification of the subtelomeric fragment yielded homogeneous product of minimum possible length even though the telomeric‐specific primer can bind, at least initially, at a multiplicity of GGGGTT repeats. Amplified 5′NTS product also was detected in an ethidium‐bromide‐stained gel when PCR was started w

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01364.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Ellobiophrya conviva clasps tentacles of the bryozoanBugula neritinawith a ring‐like structure formed from aboral extensions of its body that taper into two slender arms. The tips of the arms overlap and join to form a unique organelle, the bouton. Each arm contains a massive myoneme that splays out at the bouton. The bouton consists of the cupped tips of the arms and a cavity, which is filled with dense homogeneous material. Long digitations containing longitudinal microtubules at their periphery project from the inner surface of the tip of each arm into the cavity. Deep folds of pellicle with pores opening into their depths line the wall of the cavity. Conventional kinetosomes are not visible in the bouton, but circular or elliptical arrays of microtubules are found at the bases of digitations. The nonfunctional scopula of the adult is in a depression enclosed by pellicular folds. The bouton is distant from the scopula, but its fine structure somewhat resembles it, supporting Chatton and Lwoff's hypothesis that the cinctal arms carry parts of the scopula at their tips. The fine structure of the cinctum supports their suggestion that the cinctal arms are homologous to the spasmonemes of vorticellid peritrich

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01365.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

We observed a wide distribution of the carbohydrate epitopes galactosylα(1–3) galactose (galα1–3 gal), α‐glucoside, and α‐mannoside in mono‐ and heteroxenic trypanosomatids by using fluorescein‐labelled lectins ofEuonymus europaeus (EE)and Concanavalin A (Con A) as well as sera from acute chagasic patients who have very high levels of anti‐galα(1–3) gal antibodies. The direct fluorescence test for galα1–3 gal withEEwas positive at minimum concentrations of 6 μg/ml for heteroxenic trypanosomatids and 0.7 μg/ml for monoxenic ones and for the plant parasite,Phytomonas.On the other hand, heteroxenic trypanosomatids that infect vertebrates bound ten‐fold more Con A than monoxenic flagellates andPhytomonas.These data were confirmed in ELISA and Western Blot assays carried out with peroxidase‐labelledEEand Con A.Euonymus europaeusrecognized several glycoproteins in all trypanosomatids that we tested. Con A, however, recognized a glycoprotein cluster in heteroxenic protozoa, which ranging from 60–120 kDa, seemed to lack monoxenic parasites andPhytomonas.These findings suggest that α‐D‐mannose and α‐D‐glucose might play an important role in the interaction bet

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01366.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Studies were conducted primarily to ascertain the mode of transmission ofCryptobia dahliparasitizing the digestive tract of lumpfish (Cyclopterus lumpus). Another flagellate, morphologically similar toC. dahli, was also observed in the gut of a deepsea fish (Macrourus berglax). Several invertebrates, which are food for lumpfish, were examined for flagellates, but were neither infected nor showed evidence of cystic stages. Parasites were more abundant in the stomach, especially at about pH 5, than in other areas of the digestive tract. Transmission was achieved by pipetting the parasites into the stomach of uninfected fish, by feeding food contaminated with flagellates, and also by holding infected and uninfected fish in the same aquarium. In nature, lumpfish probably acquire parasites during winter when they aggregate and regurgitate into seawater because parasites can survive for short periods outside their host.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01367.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Twenty monoclonal antibodies were produced against trophozoites ofEntamoeba histolyticastrains HK‐9 and HM‐1: IMSS. When reactivity to various enteric protozoa was examined by an indirect fluorescence antibody test, 15 of the monoclonal antibodies were strongly reactive withE. histolyticatrophozoites. Species‐specific antigens recognized by these monoclonal antibodies were located on the plasma membrane, nucleus, cytoplasm, and cytoskeletal structures of the trophozoites. Two of the remaining five monoclonals reacted strongly with trophozoites of theE. histolytica‐like Laredo strain. The determinant antigen was located in the cytoplasm. The three remaining monoclonal antibodies were found to recognize cross‐reactive antigens betweenE. histolyticaandE. histolytica‐like Laredo,E. hartmanni, E. coli, Dientamoeba fragilis, Giardia lamblia, andTrichomonas hominis.These three antibodies were also reactive with

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01368.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The distribution of thermoreceptor systems that initiate step‐up and step‐down thermophobic responses in bisected cells ofBlepharismawas examined. Anterior cell fragments responded by ciliary reversal to a step‐down in temperature and by repression of spontaneous ciliary reversal to a step‐up. Posterior fragments responded by ciliary reversal to a step‐up in thermal stimulation and by repression of spontaneous ciliary reversal in response to step‐down stimulation. Results indicate that two kinds of thermoreceptor systems exist in the anterior half of each cell; one is responsible for ciliary reversal induced by step‐down stimulation, and the other is responsible for repression of the ciliary reversal caused by step‐up thermal stimulation. Likewise, there are also two kinds of thermoreceptor systems in the posterior half of the cell; one is responsible for ciliary reversal in response to a step‐up in temperature, and the other is responsible for the repression of ciliary reversal on a step‐down in thermal stimulation. Below about 27°C, intact cells showed ciliary reversal only when a step‐down in thermal stimulation occurred, while above about 27°C cells only responded to a step‐up in thermal stimulation. At about 27°C there was a switch in the dominant response from the anterior to the posterior

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01369.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Nuclear and cortical phenomena during dividing and resting cyst formation ofColpoda inflataare described. Cell division forms a cyst and produces two or four tomites. In each tomite, the right oral field results from the proliferation of the anterior extreme of a single kinety, and the left oral field results from the proliferation of four, five, or six somatic kineties. After macronuclear division, each macronuclear mass undergoes a chromatinic extrusion process. During resting cyst formation, the oral infraciliature of the vegetative cell is resorbed. The somatic kineties dispose in a radial way and some pairs of kinetosomes disappear. As in cell division, there is an extrusion process. From these results we conclude that the resting cysts ofColpoda inflatacannot be included in any group of the previous classifications for hypotrich resting cysts. Thus, we propose a new additional group to Walker and Maugel's classification called PKR (partial‐kinetosome‐resorbing) cy

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01370.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

We have studied in detail the immunofluorescence localizations ofTetrahymena14‐nm filament‐forming protein (49‐kDa protein) in relation to tubulin in conjugating wild‐typeTetrahymena thermophila(B strain) pairs and in pairs between B strain and star strains with defective micronuclei. The results suggest that germ nuclear behavior during conjugation may involve the following cytoskeletal structures: (1) during meiosis, microtubule structures are involved in micronuclear elongation and meiotic division; (2) at the postmeiotic stage, 49‐kDa protein network structures that are formed independently of the existence of pronuclei are involved in the selection and the survival of one of four meiotic products; (3) during the third prezygotic division, gametic pronuclear transfer, and zygote formation, a cytoskeletal structure in which the 49‐kDa protein colocalizes with microtubules and which is dependent on the existence of a normal gametic pronucleus is involved in gametic pronuclear behavior, and (4) during the postzygotic divisions, the microtubules are involved in nucle

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1991.tb01371.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY