Infraciliature, Morphogenesis and Life Cycle of Endosphaera terebrans (Suctoria, Tokophridae)

The morphology, infraciliature, and life cycle of Endosphaera terebrans , a suctorian endocommensal of peritrichs, have been studied with the aid of silver impregnation.
The life cycle of Endosphaera terebrans begins with infection of the host cell by a small larva. The swarmer has a pointed needle-like cellular projection and two rings of cilia. The swarmer penetrates the peritrich, loses the cilia, and then matures into an adult. The infraciliature of the adult form has four rows of barren kinetosomes that lack kinetodesmal fibers. By endogenous budding, a migratory larva is produced that leaves the host cell through the peristomial disc and that can infect other peritrichs.     

Asexual reproduction in the suctorianDiscophrya collini

Summary Discophrya collini reproduces asexually through the formation of a ciliated swarmer by evaginative budding. This process is initiated by the repeated replication of a single subcortical kinetosome to form a kinetosome field. The epiplasm of the multilayered cortex covering this field becomes reduced in thickness and the whole cortex invaginates to produce an internal embryonic cavity. The kinetosomes become organised into rows, and each produces a cilium which projects into the cavity. On completion of the embryonic cavity its walls are extruded through the cavity opening to form an external ciliated swarmer connected to the parent by a thin bridge of cytoplasm. It is suggested that this evagination is induced by a rapid breakdown of supporting microtubules in the cavity wall and the subsequent hydrostatic pressure exerted by the body cytoplasm. The connecting bridge shows no specialised ultrastructural features and separation of swarmer from parent probably is achieved by the active movement of the swarmer. The cytoplasm of the swarmer is similar in structure to that of the adult cell but contains a number of primordia of tentacle axonemes. The infraciliature resembles that of other suctorian swarmers. On settling, the cilia of the swarmer are lost, at least some by resorption, a stalk may be secreted and the axoneme primordia are extended to form functional tentacles.     

Fine structure of the eyes of Pseudoceros canadensis (Turbellaria,Polycladida)

Summary The cerebral and epidermal ocelli of the Müller's larva and the cerebral and tentacular eyes of the adult turbellarian Pseudoceros canadensis were studied by electron microscopy. The right cerebral ocellus of the larva consists of one cup-shaped pigmented cell and three sensory cells that bear microvilli. The left cerebral eye of the larva has the above named cells plus a sensory cell with many cilia. Evolutionary significance is attributed to the presence of both ciliary and microvillar photoreceptors in an eye of a flatworm. The one epidermal ocellus of the larva is composed of two cells: a cup-shaped pigmented one bearing flattened cilia, the presumed photoreceptors, and a cell above the cup that adds a few nonciliary lamellae to the stack of ciliary ones from the pigmented cell. The adult eyes contain only microvillar receptors; cilia were not observed.     

Lorica Construction in Eufolliculina sp. (Ciliophora,Heterotrichida)1

ABSTRACT. The structure and ultrastructure of the chitinous lorica of Eufolliculina sp. are described. The lorica is produced from precursor material secreted by the motile swarmer immediately after settling. This material is located in numerous vesicles found in the cortical region of the cells and is secreted by exocytosis. Initially, material is secreted from the ventral part of the cell to produce the attachment plate of the lorica. After this, exocytosis occurs over most of the body surface as the ampulla part of the lorica is constructed. During the later stages of lorica formation, secretion is mainly limited to the anterior of the cell as the neck is formed. The lorica is shaped mainly by the action of the cilia and by the behavior of the cell. While the neck is being formed, the anterior part of the cell is deformed by a local accumulation of cytoplasmic vacuoles. This deformation is employed in shaping the neck. No changes were detected in the organization of the cortical infraciliature during the first stages of lorica formation, but they do occur after the neck has been produced and as the swarmer develops into the sessile form.     

Notes on the biology and ecology of the parasitoids of the poplar clearwing moth, Paranthrene tabaniformis (Rott.) (Lep., Sesiidae) in Bulgaria. II. Eriborus terebrans (Gravenhorst, 1826) (Hym., Ichneumonidae)

The biology and ecology of Eriborus terebrans (Grav.), a parasitoid of the poplar clearwing moth, Paranthrene tabaniformis (Rott.), were studied during the period 1987–98. One-year-old poplar ( Populus spp.) shoots infested with P. tabaniformis larvae were collected from poplar seedlings at 11 localities in Bulgaria and examined in both field and laboratory conditions. Eriborus terebrans was recorded in seven localities as a solitary internal larval parasitoid of P. tabaniformis which developed two generations in early and mid-stage host larvae. Eriborus terebrans overwintered as a larva in P. tabaniformis overwintering larvae. In the field adult parasitoids of the overwintering generation appeared between late April/early May, and June or July. The peak activity of E. terebrans adults only coincided with the beginning of host emergence, which resulted in low levels of parasitism, being no more than 6.2%. Parasitoid adults of the summer generation appeared in late June–mid August. In this period enough larvae of the host were suitable for attacking and parasitism reached 24.4–39% in some cases. The average mortality of P. tabaniformis overwintering larvae caused by this parasitoid in Bulgaria during the period of the study was 4.7%. A significant part of the parasitized P. tabaniformis larvae constructed tunnel structures of frass and silk threads over the external openings of the galleries. It is possible that these structures protect the parasitoid cocoons from natural enemies – hyperparasitoids and predators.     

Transmission and Scanning Electron Microscopy of the Evaginative Budding Process in Heliophrya sp. (Ciliata,Suctoria)1

ABSTRACT. A sessile, tentacle-bearing protozoon, Heliophrya sp. (Suctoria, Ciliata), reproduces asexually by evaginative budding to form a ciliated swarmer, which begins metamorphosis to the adult form within 30 min of its release from the parent cell. Morphological features of embryogenesis were investigated using transmission and scanning electron microscopy and found to correspond, with certain exceptions, to the few previous reports concerning evaginative budding in suctorians. Following invagination of a portion of the pellicle to form an embryonic cavity within the parent cell, numerous kinetosomes, apparently formed de novo, organize into rows which surround the embryonic cavity and eventually develop cilia that project into the cavity. When the cavity is complete, its walls are extruded through an opening in the parent cell surface. Parent cell cytoplasm streams into the incipient swarmer, thus supplying it with at least the minimum requirement of all cytoplasmic organelles. The ciliated swarmer remains attached to its parent cell for several minutes before it detaches. A complete pellicle is formed in both parent and swarmer prior to detachment. The numerous mitochondria underlying the parent cell pellicle in the vicinity of the attachment area suggest that cross wall formation is an energy-dependent process.     

Planeticovorticella finleyi n.g., n.sp. (Peritrichia, Vorticellidae), a planktonic ciliate with a polymorphic life cycle

Abstract. Free-swimming trophonts of a sessiline peritrich ciliate were discovered in plankton samples from the Rhode River, Maryland, and main-stem Chesapeake Bay. Cultures revealed that the species comprises both free trophonts that swim with their peristomial cilia and sessile trophonts that attach to substrates with a contractile, helically-twisted talk. Trophonts with a short, rigid stalk or no definite stalk also were seen in culture. Binary fission of free-swimming trophonts usually produced a pair of trophonts attached scopula to scopula by a short, rigid stalk. These persisted for some time as distinctive, spinning doublets before their stalks broke and they separated. Binary fission of free-swimming trophonts also yielded trophont-telotroch pairs that stayed together for only a short time. Telotrochs from these pairs were presumably the source of attached trophonts. Conjugation occurred in both free and attached trophonts. Formation of microconjugants involved at least 2 successive divisions of a trophont. Possession of a helically-twisted, contractile stalk placed the peritrich in the family Vorticellidae, but its unique combination of life-cycle stages marks it as a new genus and species, Planeticovorticella, finleyi The morphology and life cycle of P. finleyi raise questions about the present classification of sessiline peritrichs and suggest that it may be at least partly artificial. Stalkless planktonic peritrichs that swim with their oral cilia as do trophonts of P. finleyi may have evolved from sessile ancestors by an alteration in the life cycle that created unstable clusters of trophonts on a single parental stalk. Free-swimming trophonts would originate from breakup of these clusters.     

Morphologie,Infraciliatur und Ökologie der limnischen Tintinnina: Tintinnidium fluviatile Stein,Tintinnidium pusillum Entz,Tintinnopsis cylindrata Daday und Codonella cratera (Leidy) (Ciliophora,Polyhymenophora)*

Synopsis. Structure, infraciliature, and ecology of 4 fresh-water Tintinnina were investigated. The lorica of Tintinnidium fluviatile is gelatinous, fragile, and contains some agglutinated material mainly of biologic origin. Its infraciliature consists of ? 10 kineties. with kinetosomes arranged in pairs. Only one basal body of a pair is ciliated, except for the uppermost 1–4 pairs which have 2 slightly elongated cilia. In Tintinnidium fluviatile. Tintinnidium pusillum, and Tintinnopsis cylindrata there are 2 prominent ventral organelles. The lorica of T. pusillum is gelatinous and coated with much agglutinated material of biologic and nonbiologic origin. Its infraciliature is similar to that of T. fluviatile, but the uppermost pair of kinetosomes has elongated cilia. The firm loricae of T. cylindrata and Codonella cratera are, built mainly of sharp-cornered structures. The infraciliature of T. cylindrata is composed of ? 10 kineties with kinetosomes not arranged in pairs. The infraciliature of C. cratera consists of ? 32 kineties, in some of which the kinetosomes are paired, e.g. ventral kinety, and in others not paired, e.g. cilia of the very prominent lateral field and of the other somatic kineties. The uppermost kinetosomes of each somatic kinety are paired and have elongated cilia. In addition, there is an unusual ventro-lateral kinety. The oral apparatus consists of adoral membranelles and a paroral membrane. The membranelles that enter the praecral cavity are very elongate, a feature perhaps unique to Polyhymenophora. The fibrillar system consists of a prominent praeoral ring formed by fibrils extending from the adoral membranelles. A finely meshed silverline system extends over the entire cell. A review of the ecology of the fresh-water Tintinnina indicated that water temperature seems to be the most essential ecologic factor. The systematic position of the Tintinnina is discussed in light of their infraciliature. It is concluded that these organisms are most closely related to Oligotrichina, and probably to Heterotrichina.     

Scanning electron microscopy of budding and metamorphosis in Discophrya collini (Root).

Budding and metamorphosis in the suctorian ciliate, Discophrya collini, have been investigated by scanning electron microscopy. The adult body form, tentacles, stalk, and attachment disk are described. A field of depressions or small pits was observed in the pellicle of adult suctorians in the early stages of bud formation. These pits deepen and coalesce until one large pore, the birth pore, remains. Cilia protrude through the pore, and as eversion of the bud proceeds the meridional arrangement of the larval ciliation is evident. After eversion is completed, a pronounced division furrow is found between the adult and soon-to-be-released swarmer. The stalk-forming region is seen on swarmers. Metamorphosing swarmers produce tentacles upon settling before any indication of ciliary resorption. Resorption of cilia and change in body form occur progressively with the production of the attachment disk and stalk.     

The contrariwise life of a parasitic, pedomorphic copepod with a non-feeding adult: ontogenesis, ecology, and evolution

Abstract. The extraordinary parasitic metanauplius larva of Caribeopsyllus amphiodiae is sexually dimorphic, with conspicuous gonads, and elaborate lens-bearing eyes. The parasites usually occur singly within their host, and grow for ≤5 months within the stomach of burrowing ophiuroids ( Amphiodia urtica ). They transform into free-living, semelparous, non-feeding adults that live only 2 weeks. The species' life-history pattern, with a larval period ∼10 × longer than the adult life span, is contrariwise to that of other copepods but not for animals with non-feeding adults of both sexes. It appears that the life cycle of C. amphiodiae is pedomorphic, and probably evolved through a delay of metamorphosis regulated by developmental hormones. We attribute the dominance of the larval phase to the greater potential for survival and growth of the enterozoic parasitic stages than of the free-living, post-metamorphic stages. We note that among marine invertebrates, non-feeding adults of both sexes occur exclusively in taxa with a complex life cycle, and that non-feeding adults of both sexes are never found in taxa that have small larvae and delayed maturation. They occur only when there is a large larva that can provide the adult stage with sufficient nutrient reserves for reproduction.     

The Permanence of the Infraciliature in Suctoria: An Electronmicroscopic Study of Pattern Formation in Tokophrya infusionum*

SYNOPSIS. The adult Tokophrya infusionum does not possess cilia, but has 20–30 barren basal bodies arranged in 6 short rows adjacent to the contractile vacuole pore. During reproduction, which is by internal budding, the contractile vacuole sinks into the parent along with the invaginating membranes that form the embryo and the wall of the brood pouch. The 6 rows of basal bodies radiate away from the pore and elongate to form 5 long ciliary rows, that encircle the anterior half of the embryo, and 1 short row at the posterior end. The contractile vacuole pore, along with several barren basal bodies, remains in the parent when the embryo is completed. The pore rises to the surface when the embryo is born. New basal bodies are then formed in the parent to replace those which were incorporated into the embryo, and formation of another embryo may begin. The cilia of the embryo are partially resorbed 10 min after the start of metamorphosis, with depolymerization of the ciliary microtubules. Later, the cilia and most of the basal bodies disappear completely, except for a group of barren basal bodies near the embryo's contractile vacuole pore, which form 6 rows and serve as an anlage for the basal bodies and cilia that arise during embryogenesis. There is, therefore, an organized infraciliature in Suctoria throughout their life cycle, and a distinct continuity of basal bodies across the generations.     

青岛沿海的自由生聚缩虫属纤毛虫(原生动物,纤毛门,缘毛目)

涉及近年来采集自青岛沿海的自由生聚缩虫属纤毛虫14种,包括9个国内新纪录:交替聚缩虫Zoothamnium alternans Claparède & Lachmann,1859,弗氏聚缩虫Z. foissneri Ji et al.,2005,黑凯聚缩虫 Z. hiketes Precht,1935,海洋聚缩虫 Z. marinum Mereschkowski, 1879,霉聚缩虫Z. mocedo Entz,1884,倪氏聚缩虫 Z. nii Ji et al.,2005,拟树状聚缩虫 Z. pararbuscula Ji et al., 2005,王氏聚缩虫Z.wangi Ji et al., 2005,许氏聚缩虫 Z. xuianum Sun et al.,2005;以及其他5个已知种:群栖聚缩虫Z. commune Kahl, 1933,双缘聚缩虫Z. duplicatum Kahl,1933,巨大聚缩虫Z.maximum Song,1986,羽状聚缩虫Z.plumula Kahl,1933,中国聚缩虫Z.sinense Song,1991.对以上各种作了简要的综合性描述,并给出了种检索表.     

Differential membrane phospholipid synthesis during the cell cycle of Caulobacter crescentus.

The pattern of phospholipid synthesis during the cell cycle of Caulobacter crescentus has been determined. Although the phospholipid composition of swarmer and stalked cells was indistinguishable in continuously labeled cultures if the two cell types were pulse-labeled for a short time period, marked differences in the pattern of phospholipid synthesis were detected. Pulse-labeled swarmer cells exhibited a higher proportion of phosphatidic acid and a lower proportion of phosphatidylglycerol. In addition, minor phospholipids were detected in the swarmer cells that were not detected in stalked cells. Stalked cells that developed directly from swarmer cells showed that same phospholipid profile as the swarmer cells. The switch to the second phospholipid profile was observed to occur at the predivisional cell stage. Because cell division then yielded a swarmer cell with a different phospholipid profile than its sibling stalked cell, the cell division process may trigger a mechanism which alters the pattern of phospholipid synthesis.     

Development of surface adhesion in Caulobacter crescentus

Caulobacter crescentus has a dimorphic life cycle composed of a motile stage and a sessile stage. In the sessile stage, C. crescentus is often found tightly attached to a surface through its adhesive holdfast. In this study, we examined the contribution of growth and external structures to the attachment of C. crescentus to abiotic surfaces. We show that the holdfast is essential but not sufficient for optimal attachment. Rather, adhesion in C. crescentus is a complex developmental process. We found that the attachment of C. crescentus to surfaces is cell cycle regulated and that growth or energy or both are essential for this process. The initial stage of attachment occurs in swarmer cells and is facilitated by flagellar motility and pili. Our results suggest that strong attachment is mediated by the synthesis of a holdfast as the swarmer cell differentiates into a stalked cell.     

Studies on the development biology of Tropilaelaps clareae Delfinado and Baker (Acarina: Laelapidae) vis a vis the threshold stage in the life cycle of Apis mellifera Linn. (Hymenoptera: Apidae).

The biology of the parasitic mite Tropilaelaps clareae Delfinado and Baker (Acarina: Laelapidae) was studied with a view to identify the time of invasion of the mite into the honey bee (Apis mellifera) brood and the threshold stage in the life cycle of the host. Honey bee brood was sequentially sampled on day 0, 4, 8, 12, 16 and 20 of development. Adult T. clareae infested the 8-day larva shortly before its cell was capped. The larvac, protonymphs, deutonymphs and adults of T. clareae were all found parasitising bright red eyed pupae during day 16 of brood development. This was identified as the most parasitised stage in the life cycle of the host. The mite developed from egg to adult in about 8 days.     

A scanning electron microscope study of the life cycle of Bothriocephalus acheilognathi Yamaguti, 1934

The stages in the life cycle of Bothriocephalus acheilognathi have been studied with the aid of scanning electron microscopy. Emergence of the coracidium occurred after 3–5 days at 20°C. Soon after hatching the coracidium began to swell and the cilia became coiled and lost their locomotory function. The surface of the coracidium was covered in protuberances of unknown function. After consumption by the copepod intermediate host, the coracidium developed into a procercoid. Upon development of a cercomer the procercoid could infect the fish definitive host. Identification of adult B. acheilognathi should be made on specimens relaxed in cold water for 10 min, and be based on the heart shaped scolex and prominent square apical disc.     

Growth and morphology of Asticcacaulis biprosthecum in defined media

The growth and morphology of cells of Asticcacaulis biprosthecum were studied in defined media to determine the effects of various compounds on the growth rate and on the expression of morphological events of the life cycle. The length of prosthecae could not be controlled by varying the concentration of inorganic phosphate as has been shown for other caulobacters. In defined media, growth was inhibited during conditions favoring rapid metabolism, apparently due to an absolute requirement for cells to complete all stages of the life cycle before cell division could occur. The morphology of cells grown under these conditions was aberrant, i.e., cells appeared elongated and branched and few prosthecae or swarmer cells were produced. Growth of a related bacterium, Asticcacaulis strain S-3, was not inhibited by conditions favoring rapid metabolism. During rapid growth, cell division in this organism occurs in the swarmer stage and prosthecae are not produced. Cell division in S-3 is not obligately coupled to completion of all stages in the complex life cycle, and morphogenesis can be controlled by cultural conditions.     

Urceolaria mitra (von Seib) Epizoic on Polycelis tenuis (IJIMA) an SEM Study.

Dense populations of Urceolaria mitra (Cilophora, Peritrichid) were observed on the surface of the planarian Polycelis tenuis (Platyhelminthes Turbellaria). Although the epizoite was primarily confined to the anterior dorsal surface of the planarian, heavily infested individuals had peritrichs attached to the posterior, lateral and ciliated ventral surfaces. Unique profiles of the skeletal ring (aboral disc) in relation to the host surface showed that some local erosion of planarian epithelium occurs. Outer and inner rows of cilia extended anti-clockwise around the peristomal disc. The cilia ran for one and one-eighth turns around the disc and overlapped in the form of a spiral when the protist was extended and feeding. The cilia appeared to beat in metachronal rhythm and exhibited a wavelength and amplitude of approximately 10μm. Regular striations having a periodicity of 1μm were observed in the periostimal membrane. A posterior or basal circlet of locomotor cilia was also observed and freeze fracture revealed an internal arrangement of microvilli, cilia and reticular membranes.     

The ability of Proteus mirabilis to sense surfaces and regulate virulence gene expression involves FliL, a flagellar basal body protein

Proteus mirabilis is a urinary tract pathogen that differentiates from a short swimmer cell to an elongated, highly flagellated swarmer cell. Swarmer cell differentiation parallels an increased expression of several virulence factors, suggesting that both processes are controlled by the same signal. The molecular nature of this signal is not known but is hypothesized to involve the inhibition of flagellar rotation. In this study, data are presented supporting the idea that conditions inhibiting flagellar rotation induce swarmer cell differentiation and implicating a rotating flagellar filament as critical to the sensing mechanism. Mutations in three genes, fliL, fliF, and fliG, encoding components of the flagellar basal body, result in the inappropriate development of swarmer cells in noninducing liquid media or hyperelongated swarmer cells on agar media. The fliL mutation was studied in detail. FliL- mutants are nonmotile and fail to synthesize flagellin, while complementation of fliL restores wild-type cell elongation but not motility. Overexpression of fliL+ in wild-type cells prevents swarmer cell differentiation and motility, a result also observed when P. mirabilis fliL+ was expressed in Escherichia coli. These results suggest that FliL plays a role in swarmer cell differentiation and implicate FliL as critical to transduction of the signal inducing swarmer cell differentiation and virulence gene expression. In concert with this idea, defects in fliL up-regulate the expression of two virulence genes, zapA and hpmB. These results support the hypothesis that P. mirabilis ascertains its location in the environment or host by assessing the status of its flagellar motors, which in turn control swarmer cell gene expression.