SPORE MORPHOLOGY OF SOME BRYOPHYTA IN EGYPT

In this work, spore morphology of eight species, Tortula muralis, Tortula brevissima, Aloina brevirostris, Syntrichia leavipila, Microbryum clavallianum (Pottiaceae); Funaria hygrometrica, Entosthodon muhlenbergii, Entosthodon attenuates (Funariaceae); were examined by Light microscopy (LM) and Scanning electron microscopy (SEM). All spores are small; the length of polar axis is between 7.5 ?m and 18.5 ?m, equatorial diameter is between 10.5 ?m and 27 ?m. The smallest spores of them are Tortula brevissima and the biggest spores of them are Entosthodon attenuates. The shapes of the spores are determined as suboblate for Tortula muralis, Aloina brevirostris, Syntrichia leavipila, and oblate for Tortula brevissima, Funaria muhlenbergii, Funaria hygrometrica, Entosthodon attenuates. The ornamentation observed can be regulate, verrucate- regulate, baculate, verrucate, clavate- foveolate, clavate, foveolate- psilate on the distal pole, spore ornamentation of the proximal face is different or less complex than the distal face. We can concluded that the spore ultrastructure give important role for identification and taxonomic significant.

Kossoviella timanica Petrosjan emend. from the Upper Devonian of North Timan: morphology and spore ultrastructure

ABSTRACTThe morphology of sterile and fertile structures (terminal strobili) of the Upper Devonian heterosporous lycopsid Kossoviella timanica Petrosjan 1984 from northern Russia (North Timan) is re-described: the axes are dichotomously branched; sterile leaves are narrow with smooth margins; the transition from sterile axes to strobili is gradual; the strobili are narrow and cylindrical, occasionally dichotomously branched; sporophylls are long, lanceolate, with crenulated margins; megasporangia with thin, mostly destroyed, sporangium walls contain one or two tetrads of large megaspores without a gula; numerous microspore tetrads are present in the microsporangia; both mega- and microspores are cavate, with a two-layered sporoderm; the outer layer of the sporoderm of both mega- and microspores consists of a net of intertwined cylindrical elements; the inner layer of the megaspore sporoderm is a basal lamina; and the inner homogeneous layer of the microspore sporoderm is split into multilamellate zones near the arms of the proximal scar. A comparison between abortive and fertile megaspores, some of which apparently were not completely mature, allows us to hypothesise that the enlargement and lateral stretching of structural units of the sporoderm, and the spaces between them, took place during the final stages of ontogenesis of megaspores along with the additional accumulation of amorphous sporopollenin. Both layers of the megaspore sporoderm, as well as the cavity between them, developed early in the ontogenesis. Although Kossoviella timanica was certainly a unique Late Devonian plant, it bears some resemblance to the Givetian heterosporous, bisporangiate lycopsid Yuguangia ordinata in having dichotomously branching axes, sporophylls with spiny margins and strobili with proximal megasporangia and distal microsporangia. Kossoviella timanica is also similar to the Famennian bisporangiate lycopsid Bisporangiostrobus harrisii in lacking a ligula and in having dichotomously branching strobili with proximal megasporangia and distal microsporangia.

First report and spore ultrastructure of Vairimorpha plodiae (Opisthokonta: Microspora) from Plodia interpunctella (Lepidoptera: Pyralidae) in Turkey

The present study describes the first isolation and characterization of

GAS2 and GAS4, a Pair of Developmentally Regulated Genes Required for Spore Wall Assembly in Saccharomyces cerevisiae

ABSTRACT The GAS multigene family of Saccharomyces cerevisiae is composed of five paralogs (GAS1 to GAS5). GAS1 is the only one of these genes that has been characterized to date. It encodes a glycosylphosphatidylinositol-anchored protein functioning as aβ (1,3)-glucan elongase and required for proper cell wall assembly during vegetative growth. In this study, we characterize the roles of the GAS2 and GAS4 genes. These genes are expressed exclusively during sporulation. Their mRNA levels showed a peak at 7 h from induction of sporulation and then decreased. Gas2 and Gas4 proteins were detected and reached maximum levels between 8 and 10 h from induction of sporulation, a time roughly coincident with spore wall assembly. The double null gas2 gas4 diploid mutant showed a severe reduction in the efficiency of sporulation, an increased permeability of the spores to exogenous substances, and production of inviable spores, whereas the single gas2 and gas4 null diploids were similar to the parental strain. An analysis of spore ultrastructure indicated that the loss of Gas2 and Gas4 proteins affected the proper attachment of the glucan to the chitosan layer, probably as a consequence of the lack of coherence of the glucan layer. The ectopic expression of GAS2 and GAS4 genes in a gas1 null mutant revealed that these proteins are redundant versions of Gas1p specialized to function in a compartment at a pH value close to neutral.

Ultrastructure and properties of Paecilomyces lilacinus spores

Strains of the filamentous soil fungus Paecilomyces lilacinus are currently being developed for use as biological control agents against root-knot, cyst, and other plant-parasitic nematodes. The inoculum applied in the field consists mainly of spores. This study was undertaken to examine the size, ultrastructure, and rodlet layers of P. lilacinus spores and the effect of the culture method on structural and functional spore properties. A rodlet layer was identified on aerial spores only. Other differences noted between aerial spores and those produced in submerged culture included the size and appearance of spores and thickness of spore coat layers when examined with transmission electron microscopy. The two spore types differed in UV tolerance, with aerial spores being less sensitive to environmentally relevant UV radiation. Also, viability after drying and storage was better with the aerial spores. Both spore types exhibited similar nematophagous ability.Key words: Paecilomyces lilacinus, fungal spores, rodlet layer, spore ultrastructure, UV sensitivity, biological control.