Light and electron microscopic investigations in the Dictyonemataceae (basidiolichens). II. Dictyonema irpicinum

1980 ◽  
Vol 58 (9) ◽  
pp. 1005-1015 ◽  
Author(s):  
Robert D. Slocum
Keyword(s):  
Blue Green Alga ◽  
Fungal Symbiont ◽  
Electron Microscopic ◽  
Free Living ◽  
Basidiomycetous Fungus ◽  
Algal Host ◽  
Stable Association ◽  
Electron Microscopical ◽  
Microscopic Investigations

The nature of the fungus–alga association between the lichen-forming basidiomycete Dictyonema irpicinum Mont. and its Scytonema host was investigated using light and electron microscopical techniques. The lichen-like basidiocarp is established as a result of the active capture of free-living Scytonema sp. trichomes by the fungal symbiont. A septate, intracellular haustorial hypha is produced by the basidiomycetous fungus within the filamentous blue-green alga. This specialized haustorial apparatus appears to enhance the survivorship of the otherwise ephemeral fungus, allowing it to maintain a long-term, stable association with the algal host.

Light and electron microscopic investigations in the Dictyonemataceae (Basidiolichens)

1977 ◽  
Vol 55 (20) ◽  
pp. 2565-2573 ◽  
Author(s):  
Robert D. Slocum ◽  
Gary L. Floyd
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cellular Level ◽  
Fungal Symbiont ◽  
Electron Microscopic ◽  
Basidiomycetous Fungus ◽  
Transmission Electron ◽  
Fungal Symbiosis ◽  
Algal Host ◽  
Microscopic Investigations

The nature of the association between the basidiomycetous mycobiont and the blue-green phycobiont in two species of the tropical basidiolichen Dictyonema was investigated using Nomarski light optics and scanning and transmission electron microscopy. Although members of this family may exhibit either a homoiomerous or heteromerous type of thallus organization, the fungus–alga relationship at the cellular level is remarkably consistent. Scytonema filaments are intimately associated with appressorial hyphae of the mycobiont and with extensive intracellular hyphae, which appear to be unrelated to the basidiomycetous fungal symbiont. This is the first report of a lichen displaying an apparent dual fungal symbiosis with the algal host. Association with the intracellular fungus produces no discernible damage to the phycobiont and apparently does not interfere with the symbiosis involving the basidiomycetous fungus.

Convergent Beam Electron Diffraction

1978 ◽  
Vol 36 (3) ◽  
pp. 304-315
Author(s):  
G. Lehmpfuhl
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Crystal Surface ◽  
Diffraction Spot ◽  
Crystal Thickness ◽  
Large Area ◽  
Electron Microscopic ◽  
Additional Information ◽  
Microscopic Investigations

Introduction In electron microscopic investigations of crystalline specimens the direct observation of the electron diffraction pattern gives additional information about the specimen. The quality of this information depends on the quality of the crystals or the crystal area contributing to the diffraction pattern. By selected area diffraction in a conventional electron microscope, specimen areas as small as 1 µ in diameter can be investigated. It is well known that crystal areas of that size which must be thin enough (in the order of 1000 Å) for electron microscopic investigations are normally somewhat distorted by bending, or they are not homogeneous. Furthermore, the crystal surface is not well defined over such a large area. These are facts which cause reduction of information in the diffraction pattern. The intensity of a diffraction spot, for example, depends on the crystal thickness. If the thickness is not uniform over the investigated area, one observes an averaged intensity, so that the intensity distribution in the diffraction pattern cannot be used for an analysis unless additional information is available.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

Ultrastructural studies on Orbilia luteorubella (Discomycetes)

1978 ◽  
Vol 56 (17) ◽  
pp. 2006-2012 ◽  
Author(s):  
Gerald L. Benny ◽  
Don A. Samuelson ◽  
James W. Kimbrough
Keyword(s):  
Green Alga ◽  
Single Electron ◽  
Blue Green Alga ◽  
Electron Microscopic ◽  
Spore Body ◽  
Discharge Mechanism ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Transmission Electron Microscopic

Transmission electron microscopic observations made on the ascus tip of Orbilia luteorubella showed that it is truncate and that the outer ascus wall is relatively thicker at the shoulders than on the top or sides. There is no demonstrable discharge mechanism in the ascal apex of this fungus comparable with that found in the ascus tip of other supposedly related inoperculate Discomycetes, including Mollisia cinerea.Ascospores of O. luteorubella contain a single, electron-opaque spore body that appears to evolve from a mitochondrion that is attached, at one end, to the inner wall of the spore apiculus. The function of the spore body is unknown.A blue-green alga, probably of the genus Anacystis, is associated with this and at least one other Orbilia species. Since these Orbilia species are here shown to be lichenized and they do not have an ascal pore discharge mechanism, the transfer of these fungi from the Helotiales is proposed. They can probably best be treated as lichens of uncertain affinities, perhaps related to those members of Lecanorales with iodine-negative asci.

scholarly journals Nestling telomere shortening, but not telomere length, reflects developmental stress and predicts survival in wild birds

2014 ◽  
Vol 281 (1785) ◽  
pp. 20133287 ◽  
Author(s):  
Jelle J. Boonekamp ◽  
G. A. Mulder ◽  
H. Martijn Salomons ◽  
Cor Dijkstra ◽  
Simon Verhulst
Keyword(s):  
Telomere Length ◽  
Brood Size ◽  
Developmental Stress ◽  
Free Living ◽  
Telomere Shortening ◽  
Developmental Effects ◽  
Fitness Consequences ◽  
Developmental Conditions ◽  
Fledgling Mass

Developmental stressors often have long-term fitness consequences, but linking offspring traits to fitness prospects has remained a challenge. Telomere length predicts mortality in adult birds, and may provide a link between developmental conditions and fitness prospects. Here, we examine the effects of manipulated brood size on growth, telomere dynamics and post-fledging survival in free-living jackdaws. Nestlings in enlarged broods achieved lower mass and lost 21% more telomere repeats relative to nestlings in reduced broods, showing that developmental stress accelerates telomere shortening. Adult telomere length was positively correlated with their telomere length as nestling ( r = 0.83). Thus, an advantage of long telomeres in nestlings is carried through to adulthood. Nestling telomere shortening predicted post-fledging survival and recruitment independent of manipulation and fledgling mass. This effect was strong, with a threefold difference in recruitment probability over the telomere shortening range. By contrast, absolute telomere length was neither affected by brood size manipulation nor related to survival. We conclude that telomere loss, but not absolute telomere length, links developmental conditions to subsequent survival and suggest that telomere shortening may provide a key to unravelling the physiological causes of developmental effects on fitness.

scholarly journals Long-term Fate of Lung Autografts Charged with Providing Total Pulmonary Function I. Light and Electron Microscopic Studies

1979 ◽  
Vol 190 (5) ◽  
pp. 648-653 ◽  
Author(s):  
FRANK J. VEITH ◽  
CHERYL M. MONTEFUSCO ◽  
SIGURD BLUMCKE ◽  
JACK W. C. HAGSTROM
Keyword(s):  
Pulmonary Function ◽  
Electron Microscopic ◽  
Microscopic Studies
Sign in / Sign up

Export Citation Format

Share Document