Whirling Disease: Reviews and Current Topics

2002 ◽  
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Small Subunit ◽  
Fish Host ◽  
Complex Life Cycle ◽  
Developmental Cycle ◽  
Myxobolus Cerebralis ◽  
Rdna Sequences ◽  
Complex Development ◽  
The One

<em>ABSTRACT. Myxobolus cerebralis </em>possesses unique phenotypic and genotypic characteristics when compared with other histozoic parasites from the phylum Myxozoa. The parasite infects the cartilage and thereby induces a serious and potentially lethal disease in salmonid fish. Comparisons of the small subunit ribosomal DNA (ssu rDNA) sequences of <em>M. cerebralis </em>to other myxozoans demonstrate that the parasite has evolved separately from other <em>Myxobolus </em>spp. that may appear in cartilage or nervous tissues of the fish host. <em>Myxobolus cerebralis </em>has a complex life cycle involving two hosts and numerous developmental stages that may divide by mitosis, endogeny, or plasmotomy, and, at one stage, by meiosis. In the salmonid host, the parasite undergoes extensive migration from initial sites of attachment to the epidermis, through the nervous system, to reach cartilage, the site where sporogenesis occurs. During this migration, parasite numbers may increase by replication. Sporogenesis is initiated by autogamy, a process typical of pansporoblastic myxosporean development that involves the union of the one cell (pericyte) with another (sporogonic). Following this union, the sporogonic cell will give rise to all subsequent cells that differentiate into the lenticular shaped spore with a diameter of approximately 10 µm. This spore or myxospore is an environmentally resistant stage characterized by two hardened valves surrounding two polar capsules with coiled filaments and a binucleate sporoplasm cell. In the fish, these spores are found only in cartilage where they reside until released from fish that die or are consumed by other fish or fish-eating animals (e.g., birds). Spores reaching the aquatic sediments can be ingested and hatch in susceptible oligochaete hosts. The released sporoplasm invades and then resides between cells of the intestinal mucosa. In contrast to the parasite in the fish host, the parasite in the oligochaete undergoes the entire developmental cycle in this location. This developmental cycle involves merogony, gametogamy or the formation of haploid gametes, and sporogony. The actinosporean spores, formed at the culmination of this development, are released into the lumen of the intestine, prior to discharging into the aquatic environment. The mechanisms underlying the complex development of <em>M. cerebralis</em>, and its interactions with both hosts, are poorly understood. Recent advances, however, are providing insights into the factors that mediate certain phases of the infection. In this review, we consider known and recently obtained information on the taxonomy, development, and life cycle of the parasite.

Observing microscopic phases of lichen life cycles on transparent substrata placed in situ

2005 ◽  
Vol 37 (5) ◽  
pp. 373-382 ◽  
Author(s):  
William B. SANDERS
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Life Cycles ◽  
Potential Significance ◽  
Free Living ◽  
Lichen Community ◽  
One Year ◽  
The One ◽  
Observation Period

The utility of plastic cover slips as a substratum for in situ study of lichen developmental stages is further explored in a neotropical foliicolous lichen community and in a European temperate corticolous community. Twenty-one months after placement in the tropical forest, the cover slips bore foliicolous lichen thalli with several species producing characteristic ascocarps and ascospores, indicating the suitability of the substratum for completion of the life cycle of these lichens. On cover slips placed within the temperate corticolous community, lichen propagules anchored to the substratum with relatively short attachment hyphae but did not develop further within the one year observation period. Intimately intermixed microbial communities of short-celled, mainly pigmented fungi and chlorophyte algae developed upon the transparent substratum. Among the algae, Trebouxia cells, often in groups showing cell division and without associated lichenizing hyphae, were commonly observed. The potential significance of the free-living populations in the life cycle of Trebouxia and in those of Trebouxia-associated lichen fungi is discussed.

scholarly journals Life cycle of Early Cambrian microalgae from theSkiagia-plexus acritarchs

2010 ◽  
Vol 84 (2) ◽  
pp. 216-230 ◽  
Author(s):  
Małgorzata Moczydłowska
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Biological Species ◽  
Complex Life Cycle ◽  
Early Cambrian ◽  
Closely Related Species ◽  
Vegetative Cells ◽  
Depositional Settings ◽  
Sexual Generation ◽  
Sheath Structure

Light microscopy studies on new materials and museum collections of early Cambrian organic-walled microfossils, informally called acritarchs, provide the observations on phenetic features that permit a comparison to certain Modern microalgae and the recognition of various developmental stages in their life cycle. the microfossils derive from various depositional settings in Estonia, Australia, Greenland, Sweden, and Poland. the exceptionally preserved microfossils reveal the internal body within the vesicle, the endocyst, and the process of releasing the endocyst from the cyst. Vegetative cells, cysts, and endocysts are distinguished, and the hypothetical reconstruction of a complex life cycle with the alternation of sexual and asexual generations is proposed. Acritarchs from theSkiagia-plexus are cysts, and likely zygotes in the sexual generation, which periodically rested as “benthic plankton.” Some microfossils of theLeiosphaeridia-plexus that are inferred to be vegetative cells were planktonic and probably haplobiontic. These form-taxa may belong to a single biological species, or a few closely related species, and represent the developmental stages and alternating generations in a complex life cycle that is expressed by polymorphic, sphaero- and acanthomorphic acritarchs. the morphological resemblance and diagnostic cell wall ultrastructure with the trilaminar sheath structure known from earlier studies suggest that the early Cambrian microfossils are the ancestral representatives and/or early lineages to the Modern class Chlorophyceae and the orders Volvocales and Chlorococcales.

scholarly journals Dynamics of venom composition across a complex life cycle

2017 ◽  
Author(s):  
Yaara Y. Columbus-Shenkar ◽  
Maria Y. Sachkova ◽  
Arie Fridrich ◽  
Vengamanaidu Modepalli ◽  
Kartik Sunagar ◽  
...  
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Complex Life Cycle ◽  
Nematostella Vectensis ◽  
Life Stages ◽  
Early Life Stages ◽  
Sea Anemones ◽  
Sessile Polyp ◽  
Venom Composition ◽  
Production Dynamics

AbstractLittle is known about venom in young developmental stages of animals. The appearance of stinging cells in very early life stages of the sea anemone Nematostella vectensis suggests that toxins and venom are synthesized already in eggs, embryos and larvae of this species. Here we harness transcriptomic and biochemical tools as well as transgenesis to study venom production dynamics in Nematostella. We find that the venom composition and arsenal of toxin-producing cells change dramatically between developmental stages of this species. These findings might be explained by the vastly different ecology of the larva and adult polyp as sea anemones develop from a miniature non-feeding mobile planula to a much larger sessile polyp that predates on other animals. Further, the results suggest a much wider and dynamic venom landscape than initially appreciated in animals with a complex life cycle.

scholarly journals Glutamine Analogues Impair Cell Proliferation, the Intracellular Cycle and Metacyclogenesis in Trypanosoma cruzi

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1628
Author(s):  
Rodolpho Ornitz Oliveira Souza ◽  
Marcell Crispim ◽  
Ariel Mariano Silber ◽  
Flávia Silva Damasceno
Keyword(s):  
Cell Proliferation ◽  
Life Cycle ◽  
Trypanosoma Cruzi ◽  
Host Cells ◽  
Glutamine Metabolism ◽  
Complex Life Cycle ◽  
Mammalian Host ◽  
Developmental Cycle ◽  
Parasite Life Cycle

Trypanosoma cruzi is the aetiologic agent of Chagas disease, which affects people in the Americas and worldwide. The parasite has a complex life cycle that alternates among mammalian hosts and insect vectors. During its life cycle, T. cruzi passes through different environments and faces nutrient shortages. It has been established that amino acids, such as proline, histidine, alanine, and glutamate, are crucial to T. cruzi survival. Recently, we described that T. cruzi can biosynthesize glutamine from glutamate and/or obtain it from the extracellular environment, and the role of glutamine in energetic metabolism and metacyclogenesis was demonstrated. In this study, we analysed the effect of glutamine analogues on the parasite life cycle. Here, we show that glutamine analogues impair cell proliferation, the developmental cycle during the infection of mammalian host cells and metacyclogenesis. Taken together, these results show that glutamine is an important metabolite for T. cruzi survival and suggest that glutamine analogues can be used as scaffolds for the development of new trypanocidal drugs. These data also reinforce the supposition that glutamine metabolism is an unexplored possible therapeutic target.

Whirling Disease: Reviews and Current Topics

2002 ◽  
Keyword(s):  
Life Cycle ◽  
Community Dynamics ◽  
Population Level ◽  
Control Measures ◽  
Complex Life Cycle ◽  
Future Research ◽  
Whirling Disease ◽  
Myxobolus Cerebralis ◽  
Natural Systems ◽  
And Function

<EM>ABSTRACT. </EM>The myxosporean parasite <em>Myxobolus cerebralis </em>is the causative agent of salmonid whirling disease. Containing its spread and limiting its effects in the Intermountain West will require judicious management programs, but such actions await a comprehensive understanding of the biology and ecology of this parasite and its hosts and how these elements interact; we do not yet know the weaknesses of this organism. To better guide efforts aimed at such an understanding, we assembled available information on the ecology of the parasite, organizing it into a conceptual model of its life cycle, to help foster understanding, focus future research, and lead eventually to a mathematical model for evaluating control measures. <em>Myxobolus cerebralis </em>has a complex life cycle with two obligate hosts, a salmonid fish and the oligochaete <em>Tubifex tubifex</em>, parasitized by the myxosporean and the actinosporean, respectively, and two infective “spore” stages, the myxospore and the triactinomyxon. This complexity is enhanced by the variable suitability of multiple salmonid species to serve as hosts, varying host suitability of genetic variants of <em>T. tubifex</em>, relatively recent introduction of <em>M. cerebralis </em>to North America, and unique traits of the parasite that preclude easy classification into conventional modeling categories. Much is known about the anatomy and function of myxospores and triactinomyxons from laboratory studies, but information on their distribution, abundance, and dispersal in natural systems is limited and based on indirect observations. Similarly, we understand development of the parasite within its hosts and resulting pathologies well but know little about host immune reactions and other mechanisms controlling proliferation within hosts or how environmental factors affect these defenses. Population-level effects on fish in natural systems have been quantified only rarely, where good prewhirling disease data exist, and effects on <em>T. tubifex </em>populations are unknown. Most rates and frequencies needed to infer relationships and model system dynamics have not been directly quantified in natural systems, but rapid progress is being made. Larger issues, including effects of <em>M. cerebralis </em>on community dynamics and ecosystem structure and function, have yet to be explored.

scholarly journals Developmental plasticity and the evolution of animal complex life cycles

2010 ◽  
Vol 365 (1540) ◽  
pp. 631-640 ◽  
Author(s):  
Alessandro Minelli ◽  
Giuseppe Fusco
Keyword(s):  
Life Cycle ◽  
Developmental Plasticity ◽  
Developmental Stages ◽  
Ecological Condition ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Complex Life Cycles ◽  
Transcription Profiles ◽  
Alternative Phenotypes ◽  
Reproductive Events

Metazoan life cycles can be complex in different ways. A number of diverse phenotypes and reproductive events can sequentially occur along the cycle, and at certain stages a variety of developmental and reproductive options can be available to the animal, the choice among which depends on a combination of organismal and environmental conditions. We hypothesize that a diversity of phenotypes arranged in developmental sequence throughout an animal's life cycle may have evolved by genetic assimilation of alternative phenotypes originally triggered by environmental cues. This is supported by similarities between the developmental mechanisms mediating phenotype change and alternative phenotype determination during ontogeny and the common ecological condition that favour both forms of phenotypic variation. The comparison of transcription profiles from different developmental stages throughout a complex life cycle with those from alternative phenotypes in closely related polyphenic animals is expected to offer critical evidence upon which to evaluate our hypothesis.

Molecular evidence linking the larval and adult stages of Mexiconema cichlasomae (Dracunculoidea: Daniconematidae) from Mexico, with notes on its phylogenetic position among Dracunculoidea

2018 ◽  
Vol 93 (05) ◽  
pp. 580-588 ◽  
Author(s):  
A.L. May-Tec ◽  
A. Martínez-Aquino ◽  
M.L. Aguirre-Macedo ◽  
V.M. Vidal-Martínez
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Gravid Female ◽  
Small Subunit ◽  
Phylogenetic Position ◽  
Molecular Evidence ◽  
Intermediate Hosts ◽  
Larval Stages ◽  
The Family ◽  
Cichlasoma Urophthalmus

AbstractWe describe the larval developmental stages and life cycle of the dracunculid nematodeMexiconema cichlasomaein both the intermediate,Argulus yucatanus(Crustacea: Branchiura), and definitive hosts,Cichlasoma urophthalmus(Perciformes: Cichlidae), from the Celestun tropical coastal lagoon, Yucatan, Mexico. The morphological analyses showed significant differences between the total length of L1 found inM. cichlasomaegravid female and L2–L3 inA. yucatanus.This result indicates that theM. cichlasomaelarval development occurs in the intermediate host. We obtained sequences from the small subunit (SSU) ribosomal marker from larval stages ofM. cichlasomaeinA. yucatanusand adult nematodes inC. urophthalmus. Our morphological and molecular results support conspecificity betweenM. cichlasomaelarvae inA. yucatanusand the adult stages inC. urophthalmus. We briefly discuss the phylogenetic position ofM. cichlasomaeamong the Daniconematidae, and provide evidence of the monophyly of the daniconematids associated with branchiurid intermediate hosts. Based on the phylogenetic results, we support the transfer of theMexiconemagenus to the family Skrjabillanidae and do not support the lowering of family Daniconematidae to subfamily.

Morphology and molecular analysis of life-cycle stages of Proctoeces maculatus (Looss, 1901) (Digenea: Fellodistomidae) in the Bizerte Lagoon, Tunisia

2015 ◽  
Vol 90 (6) ◽  
pp. 726-736 ◽  
Author(s):  
R. Antar ◽  
L. Gargouri
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Developmental Stages ◽  
Sparus Aurata ◽  
Morphological Identification ◽  
Bizerte Lagoon ◽  
Rdna Sequences ◽  
Life Cycle Stages ◽  
Mediterranean Mussel ◽  
Second Intermediate Host

AbstractThe life cycle of Proctoeces maculatus (Looss, 1901) (Digenea, Fellodistomidae) was studied in Bizerte Lagoon (Tunisia). Three sequential hosts appear to be involved: the Mediterranean mussel Mytilus galloprovincialis Lamarck, 1819 (Mytilidae) as the first intermediate host; the polychaete Sabella pavonina Savigny, 1822 (Sabellidae), as the second intermediate host; and fishes (Lithognathus mormyrus (Linnaeus, 1758) (Sparidae), Trachinotus ovatus (Linnaeus, 1758) (Carangidae) and Sparus aurata Linnaeus, 1758 (Sparidae) as the definitive hosts. It should be noted that S. pavonina was recorded as second intermediate host for P. maculatus for the first time. Molecular confirmation of the morphological identification of the life-cycle stages of this digenean was obtained using partial 28S rDNA sequences. Comparative sequences revealed that the sporocysts and the metacercariae are conspecific but they diverged by 0.3% from the adults. The present results raised the possibility of the existence of cryptic species within the different developmental stages. However, all the present isolates differed from material from Archosargus probatocephalus in the Gulf of Mexico identified as P. maculatus.

Life-cycle of the tropical warehouse moth, Cadra cautella (Wlk.), at controlled temperatures and humidities

1965 ◽  
Vol 55 (4) ◽  
pp. 775-789 ◽  
Author(s):  
H. D. Burges ◽  
K. P. F. Haskins
Keyword(s):  
Life Cycle ◽  
Wheat Germ ◽  
Developmental Stages ◽  
Rapid Development ◽  
Adult Life ◽  
Developmental Cycle ◽  
Poor Survival ◽  
Cadra Cautella ◽  
Low Humidity ◽  
Lower Temperature

The life-cycle of five stocks of Cadra cautella (Wlk.) (Phycitidae) and the duration of the various developmental stages were studied at temperatures from 15 to 37·5°C. and relative humidities between 0 and 100 per cent, on a mixture of wheatfeed, wheat germ and yeast. At 70 per cent. R.H., the limiting temperatures for the completion of the life-cycle were about 15°C. and about 36°C. At 30°C., the limiting humidities were about 20 and above 90 per cent. R.H. Development was quickest at 30–32°C. and 70–80 per cent. R.H., taking 29–30 days from the laying of the egg to the formation of the adult moth. This period increased with lower temperature and humidity, reaching 145·0 days at 15·5°C. (70 per cent. R.H.) and 51 days at 20 per cent. R.H. (30°C.).Near the optimal conditions for rapid development, the egg occupied about 10 per cent, of the developmental cycle, the larva about 70 per cent, and the pupa 20.Temperature influenced the duration of all developmental stages, but humidity had a marked effect only on the larva. The pupation of some mature larvae was delayed: whether or not this delay is a diapause is discussed. Virgin adults lived 4·8 days at 35°C. to 18·9 days at 17·5°C. (70 per cent. R.H.). At 30°C., low humidity halved the length of adult life.The mortality, even in favourable conditions, was often rather high, principally among eggs and young larvae.There was poor survival of small numbers of larvae kept on maize and on cocoa beans, but survival on wheat was similar to that on the usual food mixture. The developmental period on wheatfeed alone was shortened by the addition of honey or glycerine or a combination of wheat germ and yeast.The incidence of disease is discussed.

scholarly journals Dynamics of venom composition across a complex life cycle

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Yaara Y Columbus-Shenkar ◽  
Maria Y Sachkova ◽  
Jason Macrander ◽  
Arie Fridrich ◽  
Vengamanaidu Modepalli ◽  
...  
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Interspecific Interactions ◽  
Life Stage ◽  
Complex Life Cycle ◽  
Sessile Polyp ◽  
Venom Composition ◽  
Transgenic Tools ◽  
Eggs And Larvae ◽  
Production Dynamics

Little is known about venom in young developmental stages of animals. The appearance of toxins and stinging cells during early embryonic stages in the sea anemone Nematostella vectensis suggests that venom is already expressed in eggs and larvae of this species. Here, we harness transcriptomic, biochemical and transgenic tools to study venom production dynamics in Nematostella. We find that venom composition and arsenal of toxin-producing cells change dramatically between developmental stages of this species. These findings can be explained by the vastly different interspecific interactions of each life stage, as individuals develop from a miniature non-feeding mobile planula to a larger sessile polyp that predates on other animals and interact differently with predators. Indeed, behavioral assays involving prey, predators and Nematostella are consistent with this hypothesis. Further, the results of this work suggest a much wider and dynamic venom landscape than initially appreciated in animals with a complex life cycle.

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