Characteristics of Soil Algae Relating to Crust Formation

Durrell, L. W.; Shields, Lora Mangum

doi:10.2307/3223709

Cited by 56 publications

(28 citation statements)

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“…Cell cultures (200 ml) of WT, UV16, and UV16-40 were harvested at 2 x 107 cells per ml, centrifuged, and suspended in 10 mM sodium phosphate buffer, pH 7.2, to give 3.5 x 109 cells per ml in 0.8 ml and placed at -20°C overnight. The cells were thawed at 20°C and the following were added: lysozyme to 5 mg/ml; EDTA to 10 mM; and 0.08 ml of hemicellulase extract (1,8) prepared by incubating 1 g of crude hemicellulase (Sigma Chemical Co.) in 1 ml of cell suspension buffer at 65°C for 30 min. The cells were incubated at 37°C for 3 h with occasional agitation, and then an equal volume of 0.2 M sodium acetate, pH 5.5, was added.…”

Section: Methodsmentioning

confidence: 99%

Mutations that affect structure and assembly of light-harvesting proteins in the cyanobacterium Synechocystis sp. strain 6701

Anderson¹,

Rayner²,

Eiserling³

1987

J Bacteriol

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The unicellular cyanobacterium Synechocystis sp. strain 6701 was mutagenized with UV irradiation and screened for pigment changes that indicated genetic lesions involving the light-harvesting proteins of the phycobilisome. A previous examination of the pigment mutant UV16 showed an assembly defect in the phycocyanin component of the phycobilisome. Mutagenesis of UV16 produced an additional double mutant, UV16-40, with decreased phycoerythrin content. Phycocyanin and phycoerythrin were isolated from UV16-40 and compared with normal biliproteins. The results suggested that the UV16 mutation affected the a subunit of phycocyanin, while the phycoerythrin subunit from UV16-40 had lost one of its three chromophores. Characterization of the unassembled phycobilisome components in these mutants suggests that these strains will be useful for probing in vivo the regulated expression and assembly of phycobilisomes.Phycobilisomes are the light-harvesting structures of cyanobacteria and red algae. Composed of chromophoric biliproteins and nonchromophoric linker proteins, phycobilisomes are organized into two structural domains, the core and the rods (reviewed in reference 12). The core is associated with the thylakoid membrane and contains the allophycocyanin (AP) biliproteins. The rods are attached to the membrane-distal periphery of the core and, in the unicellular cyanobacterium Synechocystis sp. strain 6701, contain phycocyanin (PC) and phycoerythrin (PE) biliproteins and four linker proteins of 27, 30.5, 31.5, and 33.5 kilodaltons (kDa) (9, 12).UV irradiation has been used to obtain pigment mutants in strain 6701 (3). Preliminary characterization of a phycobilisome assembly mutant, UV16, demonstrated intact core substructures with little PC bound and soluble PC trimers that were free of linker proteins. The PE in UV16 assembled into rod substructures that contained the 31.5-and 30.5-kDa PE linker proteins and cosedimented with cores on a sucrose gradient (3). The UV16 strain was mutagenized to find a mutant that would eliminate PE contamination of cores. We obtained the mutant strain UV16-40 from a colony with lighter green pigmentation, indicating decreased PE relative to the parent strain, UV16. We examined relative biliprotein content, assembly of rod components, and the chromatic adaptation response (22) in the UV16 and UV16-40 strains. The defective PC and PE biliproteins were isolated from UV16-40 and compared with normal PC and PE from wildtype (WT) and UV16 strains. The resulting differences suggested the presence of structural lesions in the PC ax subunit of UV16 and the PE ,B subunit of UV16-40. MATERIALS AND METHODSStrains, media, and culture conditions. Synechocystis sp. strain 6701 (Pasteur Culture Collection) and mutant strains were grown in the medium and light conditions described previously (3). Strains UV16 and UV16-40 were obtained after UV mutagenesis (3) tively. The spontaneous reversion frequency for both mutants was not measured directly, but is less than lo-5. To assay chromatic adaptation respo...

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Section: Methodsmentioning

confidence: 99%

Mutations that affect structure and assembly of light-harvesting proteins in the cyanobacterium Synechocystis sp. strain 6701

Anderson¹,

Rayner²,

Eiserling³

1987

J Bacteriol

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“…Many terrestrial cyanobacteria possess a sheath. Under conditions where water is a limiting factor, thick mucilaginous sheaths surrounding the trichomes may favour the rapid uptake of water after desiccation (Durrell & Shields, 1961) and help to maintain a relatively humid environment for the organisms (Shephard, 1987). In C. epipsammum, in which a sheath was not detected, the thick, presumably cellulose-containing cell wall may serve the same function as a sheath, since pure cellulose has a high capacity to retain water (Updegraff, 1969).…”

Section: Discussionmentioning

confidence: 99%

Crinalium epipsammum sp. nov.: a filamentous cyanobacterium with trichomes composed of elliptical cells and containing poly- -(1,4) glucar (cellulose)

Winder¹,

Stal²,

Mur³

1990

Journal of General Microbiology

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This paper describes the isolation and characterization of a new species of cyanobacterium, Crinalium epipSammum. The assignment to the genus Crinalium, first described by Crow (1927), is based on a property which is u n d for cyanobacteria: trichomes viewed in cross-section are elliptical rather than circular. This organism was isolated from the surface layer of sandy soil of coastal dunes in The Netherlands. The organism is non-motile and drought resistant, and its cell surface is hydrophilic. The temperature optimum for growth is 25 OC. The mean DNA base composition is 33.9 mol% G + C. The cell wall is relatively thick and contains poly-p-(1,4)glucan (duIose), which is unusual for qanobadria.

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“…Among crust properties, crust biomass may play an important role in controlling runo yield. Since exopolysaccharide sheaths may greatly absorb water (Durrell and Shields, 1961;Campbell, 1979), enhancing crust saturation (Kidron, 1995), and consequently resulting in surface sealing (Verrechia et al, 1995;Mazor et al, 1996;Kidron et al, 1999), crust biomass may play an important role in retarding in®ltration (Kidron, 1995). The higher biomass characterizing the north-facing slopes may thus explain the high responsiveness of the north-facing plots.…”

Section: Runo On North Versus South Exposuresmentioning

confidence: 99%

“…Runo is one of the main water sources responsible for water redistribution within a given ecosystem (Evenari et al, 1971). Water redistribution may be of prime importance in arid ecosystems (Noy-Meir, 1973), and especially on sandy dunes where the likelihood of runo is very low.…”

Section: Introductionmentioning

confidence: 99%

Differential water distribution over dune slopes as affected by slope position and microbiotic crust, Negev Desert, Israel

Kidron

1999

Hydrol. Process.

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Abstract:Runo is one of the main water sources responsible for water redistribution within a given ecosystem. Water redistribution is especially important in arid regions, and may be of great importance on sandy dunes, where the likelihood of runo is low owing to the high in®ltration rates of sand. Redistribution of water may signi®cantly aect plant and animal distribution, and may explain vegetation patterns within an ecosystem.Runo yield over sandy dune slopes in the western Negev Desert was measured under natural conditions during 1990±1994. The magnitude of runo yield on dierent slope sections and on north and south exposures was established. The results demonstrate that while slope position controlled the microbiotic crust cover, crust cover and crust biomass controlled the amounts of runo obtained. Whereas no runo was measured on the upper dune sections devoid of crust, only meagre quantities were measured on the midslope sections, characterized by discontinuous crust cover. Substantially larger amounts were, however, obtained at the bottoms of the slopes, characterized by continuous crust cover. North-facing slopes, usually characterized by a chlorophyll a content of 29±41 mg m À2 , yielded on average 3 . 2 times more runo than south-facing footslopes, characterized by a 17 mg m À2 chlorophyll a content. Whereas microbiotic crust was found to be responsible for runo generation, additional water supply owing to runo may also explain the occurrence of a high biomass crust and the dense vegetation belt at the dune±interdune interface of the northern exposure, where runo tends to collect. Thus, whereas crust may reduce in®ltration in certain habitats, runo generated by crust may also be responsible for the promotion of crust growth in other habitats. Runo may also be used to promote vegetation growth at the dune footslopes. The possibility of using runo to facilitate agroforestry is discussed.

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Characteristics of Soil Algae Relating to Crust Formation

Cited by 56 publications

References 0 publications

Mutations that affect structure and assembly of light-harvesting proteins in the cyanobacterium Synechocystis sp. strain 6701

Mutations that affect structure and assembly of light-harvesting proteins in the cyanobacterium Synechocystis sp. strain 6701

Crinalium epipsammum sp. nov.: a filamentous cyanobacterium with trichomes composed of elliptical cells and containing poly- -(1,4) glucar (cellulose)

Differential water distribution over dune slopes as affected by slope position and microbiotic crust, Negev Desert, Israel

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