Phagocytized Intracellular Microsporidian Blocks Phagosome Acidification and Phagosome-Lysosome Fusion

This study examines the relationship between phagosome acidification and phagosome-lysosome fusion events using phagocytized Glugea hertwigi spores. The incidence of lysosome fusion with Glugea spores in phagosomes of mouse peritoneal macrophages and of Tetrahymena was monitored using colloidal gold and acridine orange as labels for secondary lysosomes. Over 80% of the Glugea phagosomes remained segregated from the labeled compartments in macrophages after 60 min; this inhibition of fusion was still evident after 4 h. In Tetrahymena, Glugea spores also showed a high capacity to block fusion with secondary lysosomes (67%); however, spores coated with cationized ferritin showed an 80% fusion rate with labeled acidic compartments (i.e. lysosomes) after 60 min with both Tetrahymena and macrophages. The pH of phagosome compartments was monitored by measuring the emissions of fluorescein isothiocyanate (FITQ-labeled Glugea ingested by Tetrahymena. Tetrahymena phagosomes with FITC-Glugea did not acidify within the first hour after phagocytosis; however, phagosomes with cationized ferritin-labeled Glugea underwent acidification during this time period. This acidification took place although the capability of the host cells' lysosomes to fuse was blocked by pretreatment with poly-D-glutamic acid. The cationized ferritin bound to Glugea spores was uncoupled from the spore wall prior to fusion with colloidal gold-labeled compartments. In vitro testing showed that ferritin dissociation requires an acid pH, indicating that phagosomes acidify prior to lysosome fusion.     

Early Morphogenesis of Glugea-lnduced Xenomas in Laboratory-Reared Flounder

Glugea stephani-infecled submucosal cells of laboratory-reared winter flounder, Pseudopleuronectes americanus, change to unique giant cell xenomas. These cells hypertrophy while the intracellular Glugea propagate to high numbers in the cytoplasm and eventually overrun the host cell. The xenomas slowly reach 20-25 muml;m (at 17°C) by day 10 after parasite invasion. These xenomas (eight often examined by electron microscopy) are coated with a mucus-like envelope onto which is attached a layer of endothelial ceils. The 10-day xenomas display (a) host cell endonuclear polyploidization and amitosis, (b) limited parasite growth and reproduction, and (c) a host cell cytoplasm structure similar to that seen in undifferentiated phagocytes. Glugea parasites do not induce obvious cell degenerative effects in 10-day xenomas; the 20-day xenomas are hypertrophied to 70-100 m?m. These cells are characterized by (a) a host cell component denuded of endoplasmic reticulum and phagosome membrane, (b) a reduction in host cell ribosomes and the disappearance of host cell cytoskeletal assemblages, including microtubules, and (c) a significant increase in vegetative Glugea within xenomas. Evidence indicates cytoplasmic calcium of the host cell xenoma is perturbed by the intracellular Glugea; the alterations in the host cell calcium domains may be a big factor in the induction of the block of mitosis in the host cell and in the disruption in its cytoskeletal controls.     

Light and Electron Microscope Study of a New Species of Glugea (Microsporida,Nosematidae) in the 4-Spined Stickleback Apeltes quadracus*

SYNOPSIS. Cell hypertrophy tumors (xenomas) associated with Glugea weissenbergi n. sp. frequently occur under the peritoneum (parietal or visceral) of Apeltes quadracus (Mitchell) near Solomons Island, Maryland. The microsporidan is similar to the type species, G. anomala (Moniez, 1887) Gurley, 1893, but has larger spores. Its fine structure corresponds with the basic pattern revealed by other authors in various species of Nosematidae. A concept of spore morphogenesis, in which the polar filament primordium is 1/2 of the nuclear isthmus present during division of the sporont, is elaborated and its implications discussed. The membrane systems of the Glugea and host cell components appear to be continuous with one another, this being an indication that the membranes are all furnished by the host cell. Lacking mitochondria and (apparently) a Golgi apparatus, Glugea is, when considered apart from the membrane system which is common to it and the host cell, a very simple organism, consisting of very little besides the genome. The simplicity of the Glugea, its very high degree of structural and physiological integration with the host cell, and the transformative development of the host cell all suggest an analogy with certain viruses.     

Vairimorpha invictae N. Sp. (Microspora: Microsporida), a Parasite of the Red Imported Fire Ant,Solenopsis invicta Buren (Hymenoptera: Formicidae)12

ABSTRACT. Vairimorpha invictae n. sp. infects the red imported fire ant, Solenopsis invicta Buren, in Brazil. The parasite is dimorphic, producing two morphologically distinct types of spores, which develop sequentially in the same fat cells or oenocytes in the fat body. The binucleate free spores develop from disporous sporonts; the uninucleate octospores develop from multinucleate sporonts within a sporophorous vesicle. Infected cells are transformed into large sacs which contain both types of spores in mature adult hosts. Mature free spores are often present by the time the larvae pupate, but mature octospores are found only in adult hosts. Masses of spores may be seen through the intact cuticle by low power phase-contrast microscopy; there are no other physical signs and no behavioral signs of infection. Attempts to transmit the infection in the laboratory failed.     

The Ultrastructure of Spores (Protozoa: Microsporida) from Lophius americanus,the Angler Fish1

ABSTRACT. Spinal and cranial ganglia of American angler fish, Lophius americanus, are often infected with microsporidia. This protozoon elicits the formation of large, spore-filled, hypertrophied host cells, cysts. Previous reports of microsporidia in European lophiids identify the parasite as Spraguea lophii, a genus which has recently been shown to be dimorphic. The spores from L. americanus are monomorphic (2.8 × 1.5 μm) and uninucleate. Each spore contains a polar tube that forms six to nine coils. Spraguea lophii differs from the microsporidium described in L. americanus in several ways. Spraguea lophii has two spore types: a large spore (4.0 × 1.25 μm) containing a diplokaryon and three to four polar tube coils and a smaller uninucleate spore (3.5 × 1.5 μm) with five to six polar tube coils. Because of these major differences, the microsporidium from L. americanus is removed from the genus Spraguea and returned to its original genus, Glugea, as a new species, G. americanus n. sp. Other ultrastructural characteristics of G. americanus are included: the posterior vacuole encloses two distinct membranous structures; one is tubular and resembles a “glomerular tuft” and the second is lamellar and composed of concentric membrane whorls, additionally, the straight or manubroid portion of the polar tube proceeds beyond the posterior vacuole before it turns anteriorly and begins to coil.     

A new species of Glugea Thélohan, 1891 in the red sea bream Pagrus major (Temminck & Schlegel) (Teleostei: Sparidae) from China

A new microsporidian species is described from farmed red sea bream Pagrus major (Temminck & Schlegel) (Teleostei: Sparidae). Large numbers of spherical whitish xenomas were observed throughout the visceral organs of the host. Histological examination showed that the microsporidia caused several xenomas that were embedded in the intestinal muscularis externa or submucosa. Light and transmission electron microscopy examination of the spores also revealed morphological features typical of species of Glugea Thélohan, 1891. This microsporidian parasite has two different types of mature spores: microspores and macrospores. The spores are elongate-ovoid, with a large posterior vacuole. The polaroplast is bi-partite, with anterior and posterior parts comprising densely packed lamellae and loose membranes, respectively, and occupies approximately the anterior half of the spore. The polar filament is anisofilar, with 12–13 coils in a single layer almost touching the posterior spore wall. Comparison of the small subunit rDNA sequences revealed 92.7–98.1% identity with the sequences available from other Glugea spp. from piscine hosts. Phylogenetic analysis demonstrated that the microsporidian species studied clustered within the Glugea clade with strong support. Based on the differences in the morphological characteristics and molecular data, the microsporidian infecting P. major is considered to represent a species new to science, Glugea pagri n. sp.     

Zschokkella mugilis N. Sp. (Myxosporea: Bivalvulida) from Mullets (Teleostei: Mugilidae) of Mediterranean Waters: Light and Electron Microscopic Description

A new Myxosporea, Zschokkella mugilis n. sp., was found in the gall bladder of several mugilids. It is distinguished from all previously reported Zschokkella from mugilids by the absence of valve ornamentation and from other species by the size of the spores. Prevalence of infection was 62.5% for Mugil capito, 70% for M. cephalus and 64.3% for Liza saliens. Plasmodia with rhizoids attached to epithelial cells appeared to compromise the host as evidenced in light and transmission electron micrographs presented herein. General ultrastructure and disporous sporogenesis of Z. mugilis resembled other Myxosporeans, but sporogonic cells did not seem to be formed in pansporoblasts.     

Ortholinea alata n. sp. (Myxosporea: Ortholineidae) in the Northern Butterfly Fish Chaetodon rainfordi

Ortholinea alata n. sp. is described from the northern butterfly fish, Chaetodon rainfordi collected at Heron Island, Great Barrier Reef, Australia. Spherical, disporous trophozoites (10–15 μ) and spores were observed in the lumina of kidney tubules and collecting ducts. Spores are broadly triangular with two short, broad processes that extend dorsoventrad from the posterior end of each of the two spore valves. Valves are bisected by a suture in the plane of the polar capsules. Spores are 12.6 μ (length) × 9.6 μ (width) × 9.9 μ (length), and at the anterior end contain two spherical, divergent polar capsules measuring 4.6 ( 4.1 –5.1) μ. Sporogenesis is similar to that of renal Sphaerospora spp.: the intraluminal trophozoites of O. alata n. sp. correspond to pseudoplasmodia described for Sphaerospora spp. and no large, multinucleate plasmodia are formed. No significant histopathological changes were observed in the kidneys of infected fish.     

Tropical and Temperate: Evolutionary History of Páramo Flora

Biogeography of the tropical alpine flora of South and Central America, the páramo flora, has been studied by dividing genera into tropical, temperate, and cosmopolitan chorological flora elements. Published molecular phylogenies of páramo genera are reviewed to summarize knowledge about evolutionary history of the páramo flora and to assess congruence between chorological and phylogenetic approaches. Molecular phylogenies suggest that both the tropical and temperate regions have been important source areas for evolution of the páramo flora. Conclusions derived from chorological patterns regarding origin of genera in páramo are mostly supported by phylogenetic data. Nevertheless, in Chuquiraga, Halenia, Huperzia, and Perezia the chorological scenario is rejected, and in Chusquea-Neurolepis, Elaphoglossum, Gunnera, Halenia, Jamesonia-Eriosorus, and Lasiocephalus independent colonization events from one or several source areas are suggested. Tropical and temperate genera contributed equally to modern species richness of the páramo flora. Among temperate genera, the northern hemisphere genera gave rise to more species in páramo than did genera from the southern hemisphere. So far, no unequivocal evidence has been provided for migration of páramo genera to the temperate zones.     

The fine structure of Ameson pulvis (Microspora,Microsporida) and its implications regarding classification and chromosome cycle

Nosema pulvisPerez, 1905, Ameson pulvis (Perez) Sprague, 1977, in muscles of the crabs Carcinus maenas and C. mediterraneus from the coast of France, was observed with the electron microscope. It was found to be structurally similar to the type species A. michaelis (Sprague, 1970). Sprague, 1977, having moniliform sporogonial plasmodia, unikaryotic sporoblasts, and hirsute sporulation stages. It is treated as distinct from A. michaelis because it has slightly smaller spores (by comparison with syntype material of A. michaelis) and appears to have fewer coils in the polar filament. The results require the removal of the genus Ameson from the family Nosematidae Labbé, 1899, where Sprague (1977) had placed it under the erroneous supposition that its sporoblasts are diplokaryotic. Ameson is transferred to family Unikaryonidae Sprague, 1977. Ameson is distinguished from PereziaLéger and Duboscq, 1909, shown by Ormieres et al. to have a similar developmental pattern, by presence of appendages on its sporulation stage. A. nelsoni (Sprague, 1950), the third, and only other species of Ameson, lacks the appendages and is transferred to genus Perezia.     

The occurrence of disporousBacillus thuringiensis cells

Ultrathin sections of sporulatingBacillus thuringiensis were examined in a transmission electron microscope. Less than 1% of the about 2,000 approximately sagittal sections of the bacterial cells examined contained two endospores per cell. This finding clarifies the majority of textbook and research reports (which tend to be ambiguous), contradicts several of the most recent textbook reports, and confirms three unillustrated textbook reports, in relation to the occurrence of disporous bacilli. Electron microscopic evidence of the observation is presented, apparently for the first time.     

Ultrastructure and phylogeny of Glugea arabica n. sp. (Microsporidia), infecting the marine fish Epinephelus polyphekadion from the Red Sea

A new microsporidian species, Glugea arabica n. sp., is reported infecting the intestinal wall of the marine teleost Epinephelus polyphekadion (=microdon) collected from the Red Sea coast off Saudi Arabia, and described on the basis of microscopic and molecular procedures. Spherical blackish xenomas formed parasitophorous vacuoles completely packed with several parasitic developmental stages, including spores. The nuclei were monokaryotic in all developmental stages. Spores were ellipsoidal to pyriform and measured 6.3 ± 0.3 (5.9–6.6) μm in length and 3.3 ± 0.4 (2.9–3.7) μm in width. A lamellar polaroplast surrounded the uncoiled portion of the polar filament, which extended into the spore's posterior pole and formed 27–29 coils organized in three or four rows. The posterior vacuole, located at the spore's posterior pole, appeared surrounded by the polar filament coils and displayed an irregular matrix composed of light material, in which was located the posterosome. Molecular analysis of the rRNA genes, including the ITS region, was performed using maximum parsimony, neighbor-joining and maximum likelihood methodologies. The ultrastructural features observed, in combination with the molecular data analysed, suggests the parasite to be a new species of the genus Glugea.     

An Ultrastructural Study of the Myxosporeans,Sphaerospoa angulata and Sphaerospora carassii,in the Common Carp,Cyprinus carpio L.1

Sporogenesis of Sphaerospora angulata occurs in the lumen of renal tubules, and of Sphaerospora carassii sporogenesis occurs in the gill epithelium of carp (Cyprinus carpio) from Hungarian pond farms. In infected fish, the lumen of the renal tubules is filled with disporous pansporoblasts of S. angulata. Spores are formed through the participation of paired valvogenic and capsulogenic cells, and a dikaryotic sporoplasm, all of which lie in the cytoplasm of an envelope cell. The polar filament is formed through the apparent invagination of components of the elongate external tubule into the capsular primordium, coupled with the incorporation of dense material from the lumen of the primordium and external tubule. The cytological events leading to spore formation in monosporous pansporoblasts of S. carassii are similar to those of S. angulata and most other species of Myxosporea thus far. While neither parasite appears to induce severe pathogenesis, they may contribute to morbidity in concurrent infections with other microorganisms. Since spores of S. angulata and S. carassii are not formed in plasmodia and the earliest stage observed in this study was 2-celled, earlier stages of these parasites must occur elsewhere in the carp host.     

Molecular phylogenetics of the burrowing crayfish genus Fallicambarus (Decapoda: Cambaridae)

Ainscough, B.J., Breinholt, J.W., Robison, H.W. & Crandall, K.A. (2013). Molecular phylogenetics of the burrowing crayfish genus Fallicambarus (Decapoda: Cambaridae). —Zoologica Scripta, 42, 306–316. The crayfish genus Fallicambarus contains 19 species of primary burrowing freshwater crayfish divided into two distinct subgenera. We test current hypotheses of the phylogenetic relationships among species within the genus as well as the monophyly of the genus. Our study samples all 19 species for five gene regions (both nuclear and mitochondrial) to estimate a robust phylogenetic hypothesis for the genus. We show that the genus is not a monophyletic group. The subgenus Creaserinus does fall out as a monophyletic group, but distinct from the subgenus Fallicambarus. The subgenus Fallicambarus appears to be monophyletic with the exception of the species Procambarus (Tenuicambarus) tenuis, which falls in the midst of this subgenus suggesting that it might be better classified as a Fallicambarus species. We also show that the species Fallicambarus fodiens is a species complex with distinct evolutionary lineages that are regionalized to different geographic areas.     

Further Observations on the Fine Structure of the Spores of Glugea weissenbergi (Microsporida,Nosematidae)*

SYNOPSIS. A Glugea xenoma sectioned and viewed with the electron microscope contained many spores with everting polar filaments. Several details not seen in previous studies of this species were observed. A specialized area with the appareance of a lattice was commonly present near the anterior end of the polaroplast. The external portion of a partially everted polar filament appeared to have about twice the diameter of the part remaining within the spore. No membrane was seen limiting the external surface of the everted portion. The everting filament had pushed thru the polar cap and the adjacent thin area of the spore wall, making the polar cap into a ring. The ring connected the proximal end of the everting filament to the inner spore membrane, thereby anchoring the filament to the spore. The electron density of some of the membranous organelles of the spore was enhanced by the use of ruthenium red.     

Life Cycle of Culicospora magna (Kudo, 1920) (Microsporida: Culicosporidae) in Culex restuans Theobald with Special Reference to Sexuality1

The life cycle of Culicospora magna (Kudo, 1920) Weiser, 1977, consists of two major developmental sequences that alternate in host individuals of successive generations, each of the sequences starting with a sporoplasm and ending with spores. The first sequence occurs in larval, pupal, and adult stages of a parental generation of the host mosquito, Culex restuans Theobald; it begins with a sporoplasm from an ingested uninucleate spore and progresses through stages in gametogony, plasmogamy, nuclear association, merogony, karyogamy, and disporous sporulation with production of binucleate spores that discharge sporoplasms into the oocytes. The second sequence occurs in egg and larval stages of a filial generation of the same host species; it begins with the binucleate sporoplasm that entered the egg, includes stages in merogony, nuclear dissociation, and mictosporous sporulation, and ends with uninucleate spores. These spores are released into the environment following death of the host and are capable of infecting new parental generation host individuals. The life cycle is conceived as an alternation of generations related to haploidy and diploidy in the nuclei, the transition from haploidy to diploidy occurring with nuclear association and the transition from diploidy to haploidy occurring with nuclear dissociation.     

DWnt-4 and Wingless have distinct activities in the Drosophila dorsal epidermis

Wnt genes are often expressed in overlapping patterns, where they affect a wide array of developmental processes. To address the way in which various Wnt signals elicit distinct effects we compared the activities of two Wnt genes in Drosophila, DWnt-4, and wingless. We show that these Wnt signals produce distinct responses in cells of the dorsal embryonic epidermis. Whereas wingless acts independently of hedgehog signaling in these cells, we show that DWnt-4 requires Hh to elicit its effects. We also show that expression of Wg signal transduction components does not mimic expression of DWnt-4, suggesting that DWnt-4 signaling proceeds through a distinct pathway. The dorsal epidermis may therefore be useful in the identification of novel Wnt signaling components. Received: 16 August 1999 / Accepted: 19 August 1999     

The ultrastructure of three microsporidia from winter moth,Operophtera brumata (L.), and the establishment of a new genus Cystosporogenes n.g. for Pleistophora operophterae (Canning, 1960)

Summary The ultrastructure of three species of microsporidia in winter moths, Operophtera brumata (L.), has been used to consolidate taxonomic assessments previously based on light microscopy. The characters formerly used to assign Nosema operophterae Canning, 1960 to a new genus Orthosoma Canning, Wigley & Barker, 1983, namely that the nuclei are isolated and that sporoblasts are separated from ribbon-shaped multinucleate (2, 4, 8 or rarely 12 nuclei) sporonts, were upheld at the ultrastructural level. Development was in contact with the cell cytoplasm but all stages, which must have included meronts, had an electron dense surface coat. Nosema wistmansi Canning, Wigley & Barker, 1983, was found to be ultrastructurally typical of the genus Nosema Naegeli, 1857. An unusual feature of this species was the close association of cysternae of host endoplasmic reticulum with the surface of meronts, an association lost in sporogony. Pleistophora operophterae (Canning, 1960) has been transferred, on ultrastructural criteria, to a new genus Cystosporogenes n.g. Nuclei are isolated; all stages develop in a vesicle bounded by an envelope of enigmatic origin; this envelope persists around the spores as a sporophorous vesicle; division of the sporont within this vesicle is by budding and the number of sporoblasts, and therefore spores, is variable up to about 60.Microsporidia which undergo multisporous sporogony in sporophorous vesicles are now distributed among seven genera. These are: Glugea Thélohan, 1891; Pleistophora Gurley, 1893; Pseudopleistophora Sprague, 1977; Vavraia Weiser, 1977; Baculea Loubès & Akbarieh, 1978; Polydispyrenia Canning & Hazard, 1982 and Cystosporogenes n.g. New genera would appear to be needed for Pleistophora sp. of Sandars & Poinar (1976) and Pleistophora sp. of Percy, Wilson & Burke (1982). ac]19840404     

Phylogenetic reassessment of gorals with new evidence from northern Myanmar reveals five distinct species

Researchers have recognised one to seven species of goral (Naemorhedus spp., Caprinae, Bovidae). We compared all available whole mitogenomic sequences, including eight new ones from northern Myanmar, and now recognise five distinct species. Naemorhedus caudatus remains a valid species. Naemorhedus griseus is a synonym of Naemorhedus goral. Naemorhedus evansi is a valid species, with a geographic range that extends northwards into southwestern China. Naemorhedus cranbrooki and Naemorhedus baileyi are distinct species, not synonyms. Molecular divergence analyses suggest that goral speciation was closely related to the rapid uplift of the Qinghai-Tibetan Plateau and Hengduan Mountains from the early Pliocene to the Pleistocene.