Ascospore Development in Hansenula Anomala

Abstract

The development of ascospores of Hansenula anomala (Hansen) H. & P. Syd. was studied by electron microscopy. Within the young ascus, a double membrane develops around each of the haploid nuclei enclosing mitochondria, oil vacuoles, and endoplasmic reticulum as well. Two ascospore wall layers are deposited within the intercisternal space. The initial wall layer develops centripetally from the extremities of the base, then around the crown of the hat-shaped spore. In many spores, this initial wall is thin or incomplete around the upper portion of the crown. The second wall layer is less electron dense and is formed adjacent to and immediately within the initial layer. At maturity of the spores, no organelles remain in the epiplasm.

Pneumocystis carinii Delanoë, its Ultrastructure and Ultrastructural Affinities*

“…Some of the published electron micrographs showing ascosporogenesis in yeasts are very similar to those of Pneumocystis in the process of forming intracystic bodies (Figs. 4,7,8,9,10 in 4; Fig. 1 in 20; Fig.…”

“…These similarities range from general characters such as difficulty in fine structure preservation, paucity of cell organelles, difficulty in seeing the nucleus, presence of vacuolar spaces in the cell, similar reaction to permanganate fixation, to similarity in the fine structure of cell organelles. Thru its whole life cycle Pneumocystis has a cell membrane which is layered as in the fungi, in which the cytoplasm is limited externally by a "cytoplasmic membrane" to which other thick layers of the "cell wall" adhere (2, 4,12,21,31,62,63,65,70,73,85,104,106).…”

“…The cell membrane is smooth (Figs. 3,4,5, 6). A few medium-sized osmiophilic granules (500-700 A) -probably lipids-are located between the nucleus and the cell membrane (Figs.…”

Ultrastructure of Ceratocystis ulmi.1 II. Ascogenous system and ascosporogenesis

“…The origin of the AD membrane is still controversial. BANDONI et al (1967), BRACKER (1967), GREENHALGH et al (1970), and SYROP et al (1972 postulate that the delimiting membrane originates from investigation of the plasmalemma of the ascus. REEVES (1967) andWILSENACH et al (1965) suggest that the ER elements give rise to the ascus vesicle membranes which eventually round up the nuclei and surrounding cytoplasm.…”

“…BECKETT et al (1968), CARROLL (1969, STIERS WILSENACH et al (1965) assume that lomasomes may be involved in the wall formation. Other investigators postulate that the ER elements are important to the development and differentiation of the spore walls (BANDONI et al 1967;MOORE 1963MOORE , 1965REEVES 1967). All these investigators believe that the ascospore wall, especially secondary one, is of sporal origin.…”