Angelica V. Hofsten

Life cycle of the endoparasitic nematophagous fungus Meria coniospora: a light and electron microscopic study

The obligate endoparasitic fungus Meria coniospora lives its entire vegetative life within infected nematodes. Conidia of M. coniospora infect the nematode Panagrellus redivivus mainly in the mouth region. The infection, starting with adhesion of conidia to the nematode surface, growth of trophic hyphae, production of conidiophores and conidia, was followed using light, scanning and transmission electron microscopy.

Lipid bodies in tissue culture, somatic and zygotic embryo of Daucus carota L.: a qualitative and quantitative study

Abstract Qualitative and quantitative electron microscopic examinations were made to study lipid body accumulation in zygotic embryos and in cells and tissues of Daucus carota L. cultured in vitro. Lipid bodies were present in all types of tissue analysed. The somatic embryos, callus and cells in suspension culture had lipid bodies rather similar in appearance and no protein bodies were detected. A few lipid bodies which were indistinct and diffuse in structure without any bordering membrane, perhaps were the so-called nascent lipid bodies. Quantitative analysis using an image analysis system showed that the torpedo-shaped somatic embryos had a significantly higher proportion of lipid body area/section area than callus cells, cells in suspension culture, and other early stages of somatic embryos. Somatic embryos grown in media with different supplements had higher numbers of lipid bodies as well as a higher proportion of lipid body area/section area compared to torpedo-shaped embryos grown in basal medium containing 2% sucrose. Zygotic embryos 17 days after pollination had an ultrastructure similar to that of somatic embryos. Late stage embryos 45 days after pollination were very rich in lipid bodies and ultrastructurally similar to other common oil-bearing seeds.

BROMINE IN THE CUTICLE OF POLYSIPHONIA NIGRESCENS: LOCALIZATION AND CONTENT1

The cuticles and chloroplasts of young and old fronds of Polysiphonia nigrescens (Huds.) Grev. were analysed by quantitative X‐ray microanalysis for their content of bromine. Cuticles of old fronds contained 1.7 ± 0.14% bromine while those of young ones contained only 0.94 ± 0.22% bromine. The bromine content of the chloroplasts showed considerable variations between individual chloroplasts, but was found not to increase with age. Young fronds contained four separate layers in the cuticle when observed under the electron microscope. In the old fronds three of these layers disappeared while the remaining one became thick and very electron dense.

Continuous liquid culture of the fungus Ophiostoma multiannulatum.

Abstract A method is described by which it is possible to maintain a fungus under conditions of constant and continuous growth. By altering the rate at which fresh nutrient is added to the culture, the growth rate of the organism can be controlled. Since, hitherto, similar methods have been used exclusively in bacterial studies, the advantages of using a fungus as the experimental material are discussed.

Bromine Location in the Red Alga Odonthalia dentata

Summary X-ray microanalysis of thin sections of the red alga Odonthalia dentata (L.) Lyngby shows bromine to be located to the chloroplasts, the middle lamellae and the outer cell walls. Bacteria attached to the outer cell wall also contained bromine. Three energy peaks were observed for bromine during the analysis L α a t 1.48 k e V , K α a t 11.92 k e V a n d K β a t 13.28 k e V The bromine peaks in the X-ray microanalysis probably originate from bromophenols as no other bromine-containing compounds have been identified in sufficient concentrations in this alga. The bromophenols probably migrate in the middle lamella from the chloroplasts to the cuticle.

Basidiospore wall ultrastructure of the false-truffle Hydnangium and its phylogenetic significance

in basidiomycete systematics. Arguments for and against including false truffles in the Agaricales hinge on the interpretation ofthe character suites and the degree of importance given to them in forming phylogenetic hypotheses (e.g., Kuhner, 1980, 1984; Julich, 1981; Singer, 1986). A number of mycologists have postulated a close relationship between the false-truffle genera Hydnangium Wallr. and Podohydnangium Beaton, Pegler, & Young and the mushroom genus Laccaria Berk. & Br. (e.g., Pegler and Young, 1979; Kuhner, 1980, 1984; Julich, 1981; Beaton et al., 1984; Mueller, 1992; Mueller and Ammirati, 1993) based on similar basidiospore or? namentation. There are numerous publications illustrating basidiospore ornamentation as viewed under the scanning electron microscope for one or more of these three genera (e.g., Pegler and Young, 1969, 1971, 1979; Beaton et al., 1984; Castellano et al., 1989; Mueller, 1991, 1992). Kuhner (1980, 1984) reported that the discrete, conical echinulae observed on basidiospores of both Laccaria and Hydnangium have microfibrils that run nearly parallel to the axis of the spine. He used these wall ultrastructure features, along with cytological and ecological characters, to justify placing Hydnangium and Laccaria in the same family Hydnangiaceae in his Tricholomatales (Kuhner, 1980, 1984). Based on unpublished micrographs of Hydnangium, Mueller (1992) and Mueller and Ammirati (1993) argued that this type of basidiospore wall ultrastructure is the one shared derived morphological feature that links these genera. However, while illustra? tions of the basidiospore wall ultrastructure of Laccaria were presented in Besson and Kiihner (1971) and Kiihner (1980), to our knowledge, no transmission electron micrographs showing the basidiospore wall ultrastructure of Hydnangium or Podohydnangium have been published. In this paper, we present micrographs documenting the similarity of wall ultrastructure of Hydnangium and Laccaria and discuss the phylogenetic implications of these data. Scanning electron micrographs were taken at the Field Museum of Natural History following the procedures outlined in Mueller (1991,1992). For examination on the Uppsala University Jeol 100 B transmission electron microscope, small pieces of lamellar tissue from air-dried herbari? um specimens were rehydrated in 3% KOH, fixed in 2.5% glutaraldehyde in 0.1 M phosphate buffer (pH 7.5), and washed in buffer three times. The samples were then postfixed in 2% Os04 in 0.1 M phosphate buffer for 2 h at 4 C, washed in buffer three times, dehydrated in a graded eth? anol series and propylene oxide infiltrated with Epon, and embedded in Epon that was polymerized for 48 h at 60 C. Sections of 50 nm thickness were cut with a Dupont diamond knife

Ultrastructure of Meiotic Cells and Ascospores of Ophiostoma Multiannulatum

Abstract The ultrastructure of meiotic cells and ascospores of the ascomycete Ophiostoma multiannulatum has been examined. The young asci contain nuclei, mitochondria and endoplasmic reticulum and the ripe asci are rich in lipid droplets. Thin filaments have been observed in the mitochondria, they probably consist of DNA. The ascospores are uninucleate and surrounded by a thin cell wall.