摘要:

SYNOPSIS.Streptomycin (SM) and pyribenzamine (PBZ at 5 × 10−4inhibit the growth rate of Euglena gracilis var.bacillarisin the light. Growth rates based on optical density, however, differed from those based on direct cell counts. The drugs also induced chlorosis (bleaching). SM caused chlorosis 10% of plated colonies after 1 to 2 hr of exposure, 50% after 8 hr, and 100% after two days. PBZ treatment yielded no chlorotic colonies after 1 to 2 hr exposure, and only 18–20% chlorotic colonies after 5 to 15 days. Since no chlorotic colonies were initially present, these drugs must have acted directly on each cell. Resistance to bleaching probably varies among the cells of a culture. The lower incidence of bleached cells in PBZ‐treated cultures might mean that the drug affects cells only during the early stage of growth. Morphological evidence as well as the viability of the druptreated cultures showed that at equimolar concentrations SM is less toxic toEuglenathan PBZ but more readily causes bleaching. Therefore the mechanism of action of SM differs from that of PBZ. Conditions governing the PBZ effect are not completely

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01830.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.One‐day‐old chicks were less susceptible to experimental infection withE. acervidinathan were 3‐day‐old chicks. Chicks fed intact oocysts when 3 days old produced 5.3, 6.7, and 42.7 times as many oocysts and had more extensive lesions than did those fed a similar number of oocysts when 1 day old. When oocyst suspensions that contained both liberated sporocysts and intact oocysts were administered, chicks infected when 3 days old produced only 1.8, 1.3, and 2.6 times as many oocysts as did those infected when 1 day old.Examination of gizzard and intestinal contents of chicks killed 2–1½ hr after receiving massive numbers of intact oocysts showed that only a few sporocysts were liberated from oocysts in the gizzard of 1‐day‐old chicks, whereas more were liberated in the gizzard of 3‐day‐old chicks. Very few sporozoites were found in the duodenum of the 1‐day‐old chicks. but there was a linear increase in the percentages in samples from lower levels of the small intestine. In 3‐day‐old chicks, excystation in the duodenum was high and, instead of increasing, remained at about the same level in the jejunum.The far smaller number of liberated sporocysts in the gizzards of 1‐day‐old chicks is attributed to less musculature and an incompletely developed grinding surface The delayed excystation of sporozoites in the intestine of 1‐day‐old chicks is thought to be due to suboptimal concentrations of trypsin and/or other pancreatic enzymes effecting excystation.The lighter infections observed in 1‐day‐old chicks, as compared to those in chicks 3 days old, are attributed to (a) a smaller number of liberated sporocysts leaving the gizzard, (b) delayed excystation in the intestine, and (c) less opportunity for spo

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01831.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.The high speed supernatant fraction obtained from cell‐free preparations ofTetrahymena pyriformisW contains an enzyme that deaminates deoxycytidine (dC) readily, but there is no evidence for a specific dCMP deaminase. The supernatant fraction also contains an active dCMP phosphatase which is inhibited by high phosphate concentration. dC deaminase in declining order deaminates BrdC, IdC, dC, MedC and dCMP. The enzyme does not appear to have a cofactor and is unaffected by Mg† and EDTA. It exhibits a broad pH optimum. Irradiation with 570,000 r of γ‐rays did not markedly affect the activity of dC, dG or dA deamination byTetrahymenahigh speed supernatant fr

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01832.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.Regeneration of different stocks ofBlepharismarepresenting several species is retarded to different degrees by identical doses of UV radiation (2654 Å). UV susceptibility of regeneration is greater in some small‐sized stocks than in some large‐sized stocks and in stocks with a lesser amount of pigment than in the more deeply pigmented ones. For the same dose regeneration is retarded more by low‐intensity than by high‐intensity short wavelength UV radiation. The UV action spectrum for regeneration delay in the Rao A stock, determined with UV of similar intensity at various short UV wavelengths, resembles absorption by nucleoprotein more than ahsorption by other cell constituents. Post‐regeneration division is also retarded by UV, and the aotion spectrum for division delay resembles that for regeneration delay, except that 2801 A is relatively more effective in retarding division than regeneration. Possible explanations for the results are

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01833.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.Labeled fatty acids were produced by adding 10 mc acetate‐1,2‐C14to cultures ofOchrosonas danica, with a recovery of 21.4% of the radioactivity as mixed methyl esters.Individual esters, or mixtures of isomers, were isolated in amounts between 2 and 200 mg by liquid‐liquid chromatography followed by gas‐liquid chromatography. Several esters, including Δ8,11,14‐C20, Δ5,8,11,14,17‐C20, Δ7,10,13,16‐C22and Δ4,7,10,13,18‐C22were obtained pure. Linoleate and arachidonate contained not more than 4% isomers; isomerism was more pronounced with C18:3 and C20:2.The effect of different culturing conditions on fatty acid yield, composition and incorporation of C14was explored. The radioactive level of acids from the preparative run varied within a factor of 3, the average being about 1 μc/mg.All analytical and preparative procedures are described in

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01834.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.Sporozoans belonging to the genusBabesiosornawere found in the erythrocytes of a youngCatostomuscollected in northern California. This is the first record of these parasites in a North American teleost. All stages of the schizogonic cycle and also the “gametocytes” were observed in the erythrocytes of the host Descriptions and measurements of these stages are given, and comparisons with the four known species ofBabesiosomaare made. This parasite represents a new species, for which the name,Babesiosoma tetragonis, is propo

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01835.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.Merozoites fromPlasmodiunz gallinaceum(exoerythrocytic forms) have been observed with the electron microscope in thin sections of infected tissue cultures. When still in segmenter formation, at the end of the intracellular cycle, a small canaliculum can be observed in their proximal part which runs from the nuclear region down into the cytoplasmic core of the segmenter, where, in some sections, it continues directly into the endoplasmic reticulum of the core.Large, vacuole‐like empty spaces in the merozoites recall swollen mitochondria. They show short villi at the periphery, instead of the typical cristae; they resemble the mitochondria of starved tissue cells.In the distal pole of the merozoites, one or two oval bodies of great electron density are present, among several smaller granules, both structures still being of unknown significance. The rest of the cytoplasm is of great electron density and shows a fine granulation.In the young trophozoites the oval bodies and the smaller granules disappear. Also, mitochondria are not found just after parasites enter a cell. These, however, reappear soon.The contact of the trophozoites with the cytoplasm of the host is intimate. Both surface membranes of the parasite are visible, mostly intact, but showing also openings which are considered artifacts, since no images have been obtained which indicate a passage of material through them from the host to the parasite. It is believed, however, that the parasite takes up material from the host through the membranes by an osmotic process. The fading of the electron density and the greater distance between the particles of its cytoplasm in the growing parasite seem to prove this. The particles which are responsible for the electron density of the merozoites, and of the young trophozoites, do not differ in their aspect from the RNA particles of the host cells.The nucleus, which in the merozoites and in the very first intracellular stages shows a homogenous fine and dense granulation, develops a darker region later, of irregular shape, which is located eccentrically, and is considered the nucleolus of these form

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01836.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.The relationship betweenAstasia longaand a streptomycin‐bleached strain ofEuglena grocilishas been examined by several criteria. The organisms differ in their sensitivity to actinomycin D and 8‐azaguanine in their ability to incorporate C14‐labeled leucine, and in their sensitivity to a new antibiotic called primycin.Euglenaforms an induced acid phosphatase when grown in phosphate‐deficient medium, butAstasiadoes not. On the basis of these and other differences, it is suggested that these two organisms are separate genera. Understanding of cell division in these cells has been increased by discovery of an array of tubular fibrils corresponding to a spindle apparatus in the nucleus of a dividingAstasia.This finding, plus the observation that presumptive pellicle complexes are formed during prophase, clarify the fission mechanisms in these or

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01837.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.The life cycle ofR. globularisis shown to include aTretomphalusstage identified asT. bnlloides.The life cycle is further complicated by successive asexual division producing typica1 agamonts. A brief synonymy is given for the genus. Basic experiments with light and substrate variation have shown no direct response.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01838.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SYNOPSIS.Five experiments using newborn Holstein‐Friesian and weaner Hereford calves were conducted to observe the effects caused by parenteral injections of oocysts ofEimeria bovis. Sporulated oocysts were given intraperitoneally (IP), subcutaneously (SC), intramuscularly (IM) and intravenously (IV). Unsporulated oocysts or merozoites were given IP or IM.Coccidiosis developed in calves in three experiments after they were inoculated IP with sporulated oocysts. Immunity to reinfection resulted from these infections. No infections occurred at any time after SC, IM or IV inoculation with sporulated oocysts or after IP or IM inoculation with unsporulated oocysts or merozoites.Coccidiosis failed to occur in two experiments when special precautions were used to prevent puncture of the intestines during IP inoculations. There was no detectable immunological response to any of the inoculations unless intestinal infections occurred.In one experiment sporulated oocysts were exposed to 60,000 r irradiation by x‐ray in an attempt to attenuate the oocysts. Calves became infected when given orally administered oocysts irradiated at this le

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1965.tb01839.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY