ABSTRACT
During the last decade several new orders were established in the class Chytridiomycetes on the basis of zoospore ultrastructure and molecular phylogeny. Here we present the ultrastructure and molecular phylogeny of strain x-51 CALU - a parasite of the alga Tribonema gayanum, originally described as Rhizophydium sp. based on light microscopy. Detailed investigation revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets. An isolated phylogenetic position of x-51 is further confirmed by the analysis of 18S and 28S rRNA sequences, and motivates the description of a new genus and species Gromochytrium mamkaevae. The sister position of G. mamkaevae branch relative to Mesochytrium and a cluster of environmental sequences, as well as the ultrastructural differences between Gromochytrium and Mesochytrium zoospores prompted us to establish two new orders: Gromochytriales and Mesochytriales.
Subject(s)
Bacterial Toxins/toxicity , Microcystis/chemistry , Rana temporaria , Animals , Biomass , Larva/drug effects , Lethal Dose 50 , Mice , Microcystins , Peptides, Cyclic/toxicityABSTRACT
A strain of cyanobacterium of Nostoc has been isolated, and found to produce a new antibiotic cyanobacterin LU-2. The antibiotic is synthesized by the cyanobnacterium under intensive cultivation conditions in a liquid mineral medium. Cyanobacterin LU-2 is an exometabolite; its maximum accumulation in the medium is achieved at 34 degrees. Cyanobacterin LU-2 is active against many cyanobacteria tested, including those of Microcystis and Aphanizomenon which are principals to give rise to blooms in fresh water supplies. It is poorly active against green algae and inactive against fungi and bacteria. The antibiotic hinders cell division in Synechococcus sp. R-2 (PCC 7942). It causes compression of the cytoplasm and exfoliation of the cell contents from cell wall; the distance between tylacoids is increased and their destruction is observed. The antibiotic hinders markedly light-dependent oxygen evolution. Cyanobacterin LU-2 is substance of a phenolic nature containing amino-sugar.
Subject(s)
Anti-Bacterial Agents/biosynthesis , Cyanobacteria/metabolism , Amino Sugars/metabolism , Phenols/metabolism , Photosynthesis/drug effectsABSTRACT
Rod-like symbiotic bacteria in the fat body of the cockroach Cryptocercus relictus have a thin cell wall of the Gram-positive type; the nucleoplasm in "diffuse". The septum connected with a massive mesosome is formed during cell division. The bacteria in the host cells are surrounded will several host membranes. For tens of millions of years. Cryptocercus relictus has been developing in the conditions of entire geographical isolation, but the morphology of its Blattabacterium is similar to that of the symbionts of other cockroaches examined. This gives evidence to the conservative nature of the cockroach--bacterial symbiosis.
Subject(s)
Adipose Tissue/microbiology , Cockroaches/microbiology , Fat Body/microbiology , Rickettsiaceae/isolation & purification , Animals , Rickettsiaceae/ultrastructure , Siberia , SymbiosisABSTRACT
A strain of the cyanobacterium Chamaesiphon confervicola was isolated and studied. The strain multiplies by means of exospores, round cells which separate from the parent cell and attach to the substrate with a short pedicle and a mucous pad. The exospore transforms into a cylindrical cell surrounded with a sheath in the process of growth. New exospores separate from the pole of the cell opposite to the pedicle through a rupture in the sheath. Either one exospore or numerous exospores formed as a result of fragmentation of the upper part of the parent cell separate(s) from its end. The mechanism of this process does not differ from that of ordinary cellular division typical of cyanobacteria. The ultrastructure of Ch. confervicola is characterized by the presence of numerous pores in the mureic layer of the cell wall.
Subject(s)
Cyanobacteria/cytology , Cell Cycle , Cell Division , Cyanobacteria/physiology , Cyanobacteria/ultrastructure , Microscopy, Electron , Spores/physiologyABSTRACT
The particles of the cyanophage A 1(L) are located between the central homogeneous zone and the perpheral thylakoids in cells grown in the conditions optimal for photosynthesis, but the viruses are concentrated in the electron-transparent local zones near or between the thylakoids in cells exposed to 5 . 10(-6) M DCMU.
Subject(s)
Photosynthesis , Plant Viruses/ultrastructure , Cyanobacteria , Microscopy, Electron , Plant Viruses/growth & developmentABSTRACT
A pure culture of the green eukaryotic alga Chlorococcum sp. and a virus infectious for it were isolated. Infection of the culture leads to the destruction of most of the cells, although complete destruction of the culture is not usually observed. The virus particles are similar in morphology to bacteriophage and consist of a hexagonal head 220 nm long and 180 nm wide and a tail which is inside the head in a majority of the particles, but which is on the outside in some. The virus is not adsorbed on the cell membranes, but evidently penetrates into the zoospores through the flagellar channels, where particles of it are regularly found. Destruction of the nucleus and membrane structures of the cytoplasm occurs during growth of the virus, but the chloroplasts and mitochondria are retained. The membranes of infected cells are partially destroyed and the virus particles are released into the medium. The virus is designated as PLVCH (L)--page-like virus of Chlorococcum.
Subject(s)
Chlorophyta , Plant Viruses/isolation & purification , Chlorophyta/ultrastructure , Microscopy, Electron , Plant Viruses/ultrastructureABSTRACT
Intracellular and extracellular polar lamellar systems were detected in Bdellovibrio chlorellavorus, the obligate parasite of Chlorella. They were observed in negatively contrasted preparations and thin sections. These systems are considered as an essential character of the bacterium, being connected with its parasitic behaviour.
Subject(s)
Bdellovibrio/ultrastructure , Cell Membrane/ultrastructure , Intracellular Membranes/ultrastructureABSTRACT
The edges of the thylakoids are connected with the plasmalemma in the cyanobacterium Synechococcus sp., strain 715, this leading to partial compartmentalization of the cytoplasm in the cell.
Subject(s)
Bacteria/ultrastructure , Cell Membrane/ultrastructure , Cytoplasm/ultrastructure , Organoids/ultrastructureABSTRACT
The structure of the omega-particle-bacteria, growing in the micronucleus of Paramecium caudatum (Ciliata, Protozoa), was studied by electrom microscopy in the course of their life cycle. The cytoplasm of the spindle-shaped vegetative cells contains a large number of dense particles and transparent regions comprising the fibrillar material. Such cells, via several intermediate stages, are transformed into elongated twisted cells that are regarded as spores. The spore consists of two parts: homogeneous, and that containing the membrane system and rounded light bodies. The membranes are often double and connected with the fibrils. The cell wall is constructed, during all stages, of the outer membrane layer and the inner electron-dense layer.
