Doctoral Dissertations

Date of Award

8-1979

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Botany

Major Professor

Patricia L. Walne

Committee Members

Dewey L. Bunting, James D. Caponetti, James N. Dumont, Fred H. Norris

Abstract

In this investigation, the cellular ultrastructure and chemical characterization of envelopes (loricas) of Trachelomonas bulla, T. lefevrei, and T. zorensis are compared and the following topics considered: ultrastructural features useful for taxonomic purposes; comparison of organelles among Pringsheim's subgenera; ultrastructural and chemical characterization of envelopes of the species examined. The cells exhibit typically euglenoid protoplast features. The presence of an envelope distinguishes them from other members of the Euglenaceae. The only ultrastructural features of taxonomic use are chloroplast number and morphology and pyrenoid morphology. Other organelles are so similar in structure that, viewed independently of the chloroplast and envelope (lorica), they cannot be distinguished as to species. The present investigation has upheld Pringsheim's pyrenoid-based subgeneric classification of T. bulla which has many discoid chloroplasts with irregularly arranged thylakoids and no pyrenoids. Trachelomonas lefevrei has two paramylum caps and should, therefore, be removed into the double-sheathed group with T. zorensis. Both T. lefevrei and T. zorensis have elongate chloroplasts with thylakoids arranged basically in three's in the stroma and in pairs in the pyrenoid. Several ultrastructural features are very similar to those reported previously in Trachelomonas hispida var. coronata. Nuclei of some cells reveal chromosomes that are not condensed. The pellicle is intermediate in complexity to that of T. volvocina and Euglena spirogyra. Thickenings in the concave region of each strip show a bifurcation of the pellicle material and probably represent a region of articulation between strips. The paraflagellar swelling contains al-complex of structures including a dense paraflagellar body, a cross-striated band connecting the paraflagellar rod to the granular matrix, and an array of striated fibrils in the matrix itself. Two flagellar roots emanate from the basal body and extend along the reservoir wall to the vicinity of the stigma. The emergent flagellum is characterized by two rows of mastigonemes ca 4-4.5 μm and 1.5 μm in length, attached on opposite flagellar surfaces. Two types of flagellar apices can be discerned by shadowcast preparation. On one the mastigonemes are attached along the length of the flagellum to the apex, whereas on the second type the distal portion is devoid of mastigonemes and shows a more prominent helical pattern. Envelopes of Trachelomonas bulla, T. lefevrei, and T. zorensis were examined by LM, TEM, SEM, and SEM-EDX. The typically hyaline envelopes of T. bulla appear smooth or slightly rugose with LM and are shown by SEM to have a bilayered reticulate surface almost devoid of spines but with papillae on the secondary reticulum. Envelopes of T. lefevrei and T. zorensis range from hyaline to dark brown. With LM, T. lefevrei shows an elaborate corona around the apical pore and various degrees of ornamentation on the surface. SEM reveals a punctate surface with blunt or attenuate spines. Trachelomonas zorensis, with both LM and SEM, manifests a wide variety of shapes and surface patterns of punctae, spines, and papillae. Substructure of the envelope of T. bulla is granular, usually in the form of a delicate "skin" or an open reticulum. Envelopes of T. lefevrei and T. zorensis are typically fibrillar; however, envelopes of granular substructure are occasionally observed in both species. For all species investigated, the first noticeable step in envelope development is the appearance of a delicate immature envelope or "skin." Mineralization apparently occurs outside the "skin" beginning, in the region over each pellicular crest. SEM-EDX has shown that P, K, and Ca are present in all envelopes analyzed. Iron is a major component of all envelopes of T. bulla, which never darken, and in light envelopes of T. lefevrei and T. zorensis, whereas Mn is negligible. The gold envelopes of T. lefevrei have Mn and P as major components and lower concentrations of other components, including Fe. In the brown envelopes of T. lefevrei and T. zorensis, Mn is the only major peak; other constituents are negligible.

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