Some ultrastructural observations of the vegetative, resting and excysting ciliate, urostyla grandis (urostylidae, hypotrichida)

Abstract

In order to reveal the differentiation characteristics of organelles of ciliates under different physiological status, the cellular ultrastructure of Urostyla grandis was studied by transmission electron microscopy. In the resting cells most ciliary shafts, kinetosomes and sub-pellicle microtubules were resorbed, and the endoplasmic reticulum (ER) disappeared with the autophagocytosis taking place within the cytoplasm. As well, the nuclear matrix of the macronucleus was extruded into the cytoplasm, forming pseudopodia-like structures with large quantities of heterochromatin (CH) attached to the inner nuclear membrane. During excystment, membraneous structures developed and gradually increased in number to form the ER. Autophagic vacuoles (AVs) appeared containing mitochondria, paraglycogen particles (PGP), membranous structures, etc. Moreover, the number of nucleoli decreased with the chromatin, condensing in parallel with the process of recombination. Based on these observations, it could be concluded that the de-differentiation of microtubular organelles and the changes occurring in macronuclei in the resting Urostyla grandis, as well as the differentiation of cytoplasmic organelles, digestion by AVs, and the recombination of chromatin during excystment, are not similar to events that occur in non-kinetosome-resorbing cysts (NKR).

Light microscopy observations on the encystation and excystation processes of the ciliate Phacodinium metchnikoffi (Ciliophora, Phacodiniidae), including additional information on its resting cysts structure

“…This fact is also in accordance with the results of Reid and John (1983). On the basis of literature references (Martín-González et al 1992;Foissner 1993;Klionsky and Emr 2000;Gutiérrez et al 2001;Foissner 2009;Foissner and Stoeck 2009;Liu et al 2009), energy and reserve products can be stored in resting cysts in several ways: (i) Sandmaniella terricola Foissner and Stoeck, 2009, maintains food vacuoles with bacteria in the resting cysts (Foissner and Stoeck 2009), (ii) The part of energy is stored in structures called autophagic vacuoles. The autophagic vacuoles were described in several species, e.g.…”

“…The detailed description of the excystation process of ciliates is less common in literature than encystation (Gutiérrez et al 2001;Verni and Rosati 2011). The excystation of ciliates was studied in the following works: Beers (1945, 1966), Repak (1968, Grimes and Hammersmith (1980), Tsutsumi et al (2004), Akematsu and Matsuoka (2007), Liu et al (2009) and Funadani et al (2013) and other studies.…”

Coupling between ribotypic and phenotypic traits of protists across life-cycle stages and temperatures

“…The rDNA and cDNA pools of the four ciliate species yielded a total of 8,478,407 reads (Table S1). The primers were removed from the raw reads using Cutadapt v1.18 (29). The DADA2 and DECIPHER package v1.14.1 (40) was applied to model and correct substitution errors, and filter and cluster the amplicons in R (v3.6.3; 41).…”

“…The latter contains numerous nucleoli, the sites of rDNA sequences, rRNA synthesis, and ribosome subunit assembly (27). During encystment and excystment, the number and size of nucleoli varies, accompanying loss and gain of macronuclear DNA (28, 29). This raises the question of whether in ciliates cellular ribotypic CNs are more related to macronuclear size than to CV across life cycle stages.…”

How Ciliated Protists Survive by Cysts: Some Key Points During Encystment and Excystment

“…One of the crucial structures of cysts is the CW. CW has almost always been described as multiple layers (e.g., reviewed in Li et al, 2017 ), for example, two layers in Euplotes muscicola ( Rawlinson and Gates, 1985 ), three layers in Urostyla grandis ( Liu et al, 2009 ) and four layers in Parentocirrus hortualis ( Benčat’ová et al, 2016 ). Here we follow Foissner’s (2005) extensive description of CW on Meseres corlissi and depict CW as five distinct layers, naming metacyst, endocyst, mesocyst, ectocyst, and pericyst, from touching the cell body to the outmost layer.…”