摘要:

SYNOPSIS.Eimeria wenrichin. sp.,Isospora mcdowellin. sp. andCaryospora microtin. sp. are described from the cecal contents of the meadow mouse,Microtus pennsylvanicus, in Pennsylvania.C. microtiis the first member of the genus to be reported from mammals.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1960.tb00709.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SYNOPSIS.A breeding analysis of a wild strain (Indian Lake 12) of variety 1,Tetrahymena pyriformis, discloses recessive lethal alleles at two independently assorting loci. Conclusions concerning the cytogenetic behavior of this species have been verified through the scoring of a large number of offspring segregating the lethals. In particular, cytogamy does not occur in these strains with a frequency higher than 2%. if indeed it occurs at all. The finding of lethal heterozygosity in a wild strain suggests that close inbreeding usually does not take place in nature and supports the conclusion that variety 1 ofT. pyriformisis an outbreeding species.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1960.tb00710.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SYNOPSIS.Nucleic acid, the nitrogen content per cell, and cell and nuclear volume were determined in 4 green and 2 heat‐induced colorless strains ofEuglena gracilisand one strain ofAstasia longa.All strains ofEuglenawere identical in cell and nuclear volume. The deoxyribonucleic acid content per cell of the apoplastidic strains was higher than that of the corresponding green strains byI1/, times. Although their nuclei were not enlarged, Feulgen staining of the colorless strains was also more intense. The significance of the increase in DNA in experimentally induced apoplastidy is discussed. As for N total nucleic acid P, and pentosenucleic acid—the dir between the strains reflected previously established morphological and physiological relationships between them. The single strain ofAstasiastudied was identical in stru: and size with the apoplastidicEuglenastnMH Hownner. it was quite unlike them in all the biochemical characteristic; exami

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1960.tb00711.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SYNOPSIS.The structure of the excretory apparatus ofParamecium caudatumandP. aureliawas studied in electro‐micrographs of ultrathin sections. The so‐called nephridial plasma visible in light microscopy was revealed as a network of fine branching tubules (nephridial tubules), of average diameter about 200 Å, which surround the nephridial canals. The nephridial tubules are connected peripherally directly to branches of the endoplasmic reticulum, which extends throughout the organism. During diastole of the radial canals the nephridial tubules open into the nephridial canals, but this connection is broken during systole. Surrounding the nephridial plasma are bundles of larger tubular elements (about 500 Å diameter).The osmiophile wall of the terminal nephridial canal continues without change in the walls of the ampulla, the injection canal and the contractile vacuole. Contractile fibrillar elements, arranged in fiat band‐like bundles and of tubular structure (about 150‐250 A diameter) without periodic cross‐striations, begin at the top of the ampulla and extend, along the surface facing the pellicle, over the injection canal and contractile vacuole to the excretory canal, which they surround as a spiral envelope.The closing of the contractile vacuole to the excretory canal is effected by a relatively compact membrane without pores, so that the emptying of the vacuole must follow breaking of this membrane. The function of the excretory system is discussed in the light of these new o

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1960.tb00712.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SYNOPSIS.The flagella ofLophomonas striataare arranged in circular rows in a tuft‐like structure. Each one is continuous with a basal body located in the anterior region of the calyx. Each flagellum is limited by the surface membrane and is composed of nine double peripheral filaments and two central ones. The former continue below the surface and make up a large part of each basal body. Below and parallel to the calyx membrane are two layers of fibrils which appear to connect the basal bodies; the first is just below (250m/x)the surface, the other is attached to the proximal ends of the basal bodies. Extending from the latter is a delicate network of fibers which gradually disappears from view as it continues in the direction of the nucleus. The calyx membrane appears continuous at the level of the basal bodies; however, below this point it seems to be made up of a series of discrete longitudinally arid obliquely arranged lamina or plates, a condition which permits direct continuity of the cytoplasm within and without the calyx. The body ofLophomonas striatais highly as well as tightly folded in its longitudinal axis and the striations or rods are clearly located on its surface; it is suggested that these are held in place by an agglutination reaction. The rods appear to divide by transverse fission and their fine structure resembles closely that reported for certain bacteria; in fact, because of this, we think they should thus be considere

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1960.tb00713.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY