Phylogeny of Myxobolidae (Myxozoa) and the evolution of myxospore appendages in the Myxobolus clade

Genera Myxobolus Bütschli, 1882 and Henneguya Thélohan, 1892 (Myxobolidae) are specious myxozoan genera. They comprise nearly half of overall known myxozoan species diversity. A typical spore feature of Henneguya is the presence of two caudal appendages of the spore valves, which distinguishes them from species of the genus Myxobolus. Several Myxobolus spp., however, were reported to show aberrant spores with Henneguya-like caudal appendages. We found such aberrant spores in Myxobolus tsangwuensis and Myxobolus wulii. We studied the ultrastructure of M. wulii and Myxobolus oralis spores with caudal appendages by transmission electron microscopy (TEM). TEM of these aberrant spores revealed that their caudal appendages have the same ultrastructure as the appendages of Henneguya spp. Small caudal appendages of M. wulii spores observed only on TEM suggested that this character may be often overlooked and more Myxobolus species potentially have the ability to express the caudal appendages on the myxospore. In order to trace the evolution of this character, we performed broad phylogenetic analysis of all species of the family Myxobolidae which are available in GenBank including nearly 300 taxa. We found at least eight independent evolutionary origins of spores with two appendages, three origins of a single appendage and 12 apparent secondary losses of the spore projections. Therefore, genus Henneguya with typical two-tailed myxospores is polyphyletic, however a majority of its species has a common ancestor and groups in the second largest subclade of the Myxobolus clade. We also mapped the biological characteristics (host, site of infection and environment) of Myxobolidae species on the phylogenetic tree. We revealed an evident host-associated evolutionary pattern in all parts of the Myxobolus clade with a distinct and species-rich subclade containing almost exclusively species infecting species of the Order Cypriniformes.     

Ultrastructural study of the microsporidian chytridiopsis typographi (Chytridiopsida: Microspora) infecting the bark beetle,Ips typographus (Scolytidae: Coleoptera), with new data on spore dimorphism

Two types of sporogony of the microsporidian Chytridiopsis typographi in the midgut of adult bark beetle, Ips typographus, have been examined by means of light and electron microscopy. New data are reported on spore dimorphism and on the formation of pansporoblasts in two types of sporogony. Thin-walled spores, larger in size, are formed in a parasitophorous vacuole in the host columnar cells. Thick-walled spores are formed in a minimal vacuole in the host. The ultrastructure of the spore walls and the cyst wall are different from the organization in other microsporidia. Both spore types have identical internal structures and viable spores.     

A new species of Nosema from Hylobittacus apicalis (Insecta: Mecoptera: Bittacidae)

An undescribed Nosema was found infecting adults of the mecopteran Hylobittacus apicalis. This microsporidium is described herein as the first record of a microsporidium from the order Mecoptera. The slightly pyriform spores measured 4.5 × 2.4 μm. Mature spores had 9.5–10 polar filament coils irregularly grouped in the posterior end. The life cycle and ultrastructure of the developmental stages were described, and were typical of other Nosema spp. This microsporidium was regularly recorded from adult Hylobittacus apicalis populations over a 10-year period and tbe incidence of infection increased during the summer.     

Devonian Spores of <Emphasis Type="Italic">Kryshtofovichia africani</Emphasis> Nikitin (Tracheophyta): Morphology and Ultrastructure

The morphology and ultrastructure of spores of the Devonian plant Kryshtofovichia africani Nikitin are examined. The structure of ultrathin exine megaspores of K. africani is established. The exine consists of two layers: granular ectexine and lamellate endexine. Microspores have a lamellate ultrastructure with a trend toward loosening and formation of the granular structure towards the ectexine outer part. Heterospory of K. africani is apparent in both morphological characters and sporoderm ultrastructure of micro- and megaspores.     

Abnormal spore morphology and wall ultrastructure in Anemia tomentosa var. anthriscifolia and A. tomentosa var. tomentosa (Anemiaceae)

The spores of Anemia tomentosa var. anthriscifolia and A. tomentosa var. tomentosa were studied focusing the attention on their abnormalities. The study was based on fresh and herbarium material and the spores were examined with light, scanning and transmission electron microscopy. Normal, abnormal and abortive spores were observed in both taxa. The normal spores were trilete, triangular in polar view, and the ornamentation consisted of parallel ridges separated by narrow and smooth grooves. The spores were observed in monads, dyads, triads and tetrads. The abnormal spores were monolete, trilete, tetralete or alete with great variations in size. In fact, some spores were almost double the size of the normal ones. Some differences were also found in the ornamentation of the spores. Aborted and not completely developed spores were also observed in the specimens. The wall ultrastructure of the taxa was studied for the first time. The exospore was two-layered with numerous cavities inside its structure, and the perispore was also two-layered. The results revealed that the sporoderm ultrastructure of both normal and abnormal spores of the taxa analyzed was very similar.     

Histopathological effects of Bacillus thuringiensis on the midgut of tobacco hornworm larvae (Manduca sexta): Low doses compared with fasting

The cytology and ultrastructure of the midgut cells of Manduca sexta larvae are described for untreated controls, larvae which fed on a spore preparation of Bacillus thuringiensis, and larvae which were fasted for either 24 or 48 hr. New observations on the ultrastructure of midgut cells in Manduca larvae included the finding of specialized Golgi vesicles in anteriormost columnar cells and of regular arrays of expanded rough endoplasmic reticulum in goblet cells of the posterior midgut region. The present observations reveal that the columnar cells of the midgut responded cytologically in the same way to fasting as they did to exposure to the toxic spores of B. thuringiensis. The goblet cells, however, appeared unaffected by fasting but became swollen in response to feeding of B. thuringiensis spore preparation.     

Spore morphology and wall ultrastructure of Trachypteris species (Pteridaceae)

Trachypteris is a small genus consisting of four species native to America and Madagascar: Trachypteris induta, T.?pinnata, T.?gilliana, and T.?drakeana. The spores of the genus were studied using light microscopy and scanning and transmission electron microscopy. They are trilete, triangular to globose, with equatorial diameter of 29?C58???m and polar diameter of 26?C53???m. The exospore is 0.5?C1.1???m thick, plane, and two-layered. The perispore is 0.3?C6.8???m thick and two-layered. Depending on the species, two different ornamentations were observed: cristated with partially fused cristae, and ridged with partially fused ridges, forming an incomplete reticulum. Globules immersed in the perispore were occasionally observed. The systematic value of the Trachypteris spores is discussed, and their morphology and ultrastructure are compared with those of other related cheilanthoid ferns. The palynological characteristics presented here may be useful for phylogenetic studies within the Pteridaceae, and particularly within the cheilanthoid ferns.     

Light and electron microscope observations on Unikaryon legeri (Microsporida,Nosematidae), a parasite of the metacercaria of Meigymnophallus minutus in Cardium edule

Nosema legeri from the metacercariae of Meigymnophallus minutus in Cardium edule has been shown by light and electron microscopy to be disporous and to lack nuclei in diplokaryon form throughout its development. Although its ultrastructure resembles that of Encephalitozoon cuniculi and mature spores often lay in vacuoles surrounded by host membranes, dividing stages were never present in a common vacuole. Sporoblasts showed a cytoplasmic protuberance suggestive of a locomotory organelle. It is possible that movement of these stages disrupts the host cell cytoplasm and creates the vacuole in which the spores mature. The species has been transferred to the genus Unikaryon Canning, Lai and Lie and named Unikaryon legeri(Dollfus, 1912).     

Occurrence of Cyclotella ambigua Grunow (Bacillariophyta) in the Kuibyshev Reservoir

The long-term study (1989–1995) of phytoplankton from the Kuibyshev Reservoir aided by the scanning electron microscopy revealed a salt water representative of centric diatoms Cyclotella ambigua Grunow, new for the Volga River. Morphological features of the frustule including elements of valve ultrastructure (location and structure of central and marginal fultoportulae, rimoportula, striae) are studied. The similarity and difference from other species of the genus, C. exigua Håkansson, C. striata (Grunow) Grunow, C. scaldensis Muylaert et Sabbe, and C. meneghiniana Kützing, are shown. Based on original and literature data, the extended diagnosis of C. ambigua is given along with the examination of the ecology and distribution of this species, little known in Russia and abroad.     

The ultrastructure of spores ofClaviceps purpurea (Fr.) Tul.

The ultrastructure of saprophytic and parasitic spores of the AscomyceteClaviceps purpurea (Fr.) Tul. was studied. Considerable differences were found to exist between the saprophytic and parasitic spores as to morphology and fine structure. The reason for the different ultrastructural morphology is probably connected with the intensity of cell metabolism. Whereas the parasitic spores obtained from the honeydew possess the character of a resting cell with a thick electron-dense cytoplasm, abundant lipid bodies, few mitochondria, an underdeveloped and hence little active endoplasmic reticulum and with a homogenous thick cell wall, the saprophytic spores appear as cells with higher metabolic rate, containing more numerous mitochondria, a thinner cytoplasm, a highly developed endoplasmic reticulum, fewer lipid bodies and abundant large vacuoles as well as frequently a new wall layer.     

A microsporidian pathogen of the poroporo stem borer,Sceliodes cordalis (Dbld) (lepidoptera: Pyralidae): Mortality and infectivity

Experiments were conducted on each instar of Sceliodes cordalis to relate the number of Nosema sp. (NSC) spores ingested to the resulting proportions of host infection and mortality. Mortalities of each instar were low, not exceeding 39% even at the highest dose tested. Infectivities increased from an ID₅₀ of six spores for newly hatched larvae to 14,000 spores for the final fourth instar. A survey of the distribution of NSC in S. cordalis populations showed that NSC occurred at a high frequency in six out of seven sites. In a more detailed study at one site it was found that infection levels were high throughout the season.     

Substructure in exines of Artemisia vulgaris (Asteraceae)

Of the Silurian and Devonian macroplant genera described in the literature, about half have been recorded with spores. These in situ spores can be compared at generic level with only about a quarter of the dispersed spore genera described for the same period. Emphasis is here placed on the structure and sculpture of in situ and dispersed Silurian, Gedinnian and Siegenian spores, where records of macroplants with in situ spores are high compared with the Middle and Upper Devonian.A comparative study of the structure and sculpture of the in situ and dispersed spores, together with information from the macroplants recorded, suggests a fairly simple Silurian and Gedinnian flora, with the evolution of a more advanced upland flora during Siegenian times.     

Ellipsomyxa tucujuensis n. sp. (Myxozoa: Ceratomyxidae), a parasite of Satanoperca jurupari (Osteichthyes: Cichlidae) from the Brazilian Amazon

The present study describes a new coelozoic, eukaryotic microparasite of the genus Ellipsomyxa Køie, 2003 (Ceratomyxidae: Myxozoa) found parasitizing the gallbladder of Satanoperca jurupari Heckel, 1840 collected in the Curiaú River Environmental Protection Area in Macapá, Amapá state, Brazil. The fish were collected using mesh cast net. The gallbladders were examined, preserved in 80% alcohol for molecular analysis (SSU rDNA gene), and fixed in Davidson for histological slide preparation. The new parasite had a prevalence of 81% in the gallbladder, asymmetric plasmodia, irregular free spores in the bladder fluid, with no cyst formation. The spores are elliptical, with characteristics of the genus Ellipsomyxa, and they had a mean length of 10.11 (8.56–10.5) μm, mean width of 7.81 (5.96–9.56) μm, and thick walls. The polar capsules are sub-spherical in shape, slightly asymmetrical, with a mean length of 3.12 (2.31–3.99) μm and mean width of 2.5 (2.22–2.95) μm, containing polar filament with five or six coils perpendicular to the longitudinal axis of the capsule. The Bayesian Inference assigned the new species to a subclade formed by a lineage of Ellipsomyxa species from the Amazon region. Ellipsomyxa tucujuensis n. sp. is the sixth species of this genus described in fish from the Amazon region, and the first for the state of Amapá.     

Effects of a novel microsporidium on the black vine weevil, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae)

A newly discovered microsporidium infecting the black vine weevil, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae), provisionally placed in the genus Canningia, was studied to determine its impact on O. sulcatus. O. sulcatus populations from several locations were sampled and evaluated for microsporidiosis. A very low prevalence of the disease was observed in all locations surveyed (<3.0%). Laboratory studies were conducted by orally exposing both larvae and adults of O. sulcatus to varying concentrations of Canningia sp. spores. Larval bioassays at a variety of dosages (0, 10, etc.) were performed to evaluate pathogen infectivity, larval survival and growth. Adult bioassays (dosages: 0, 10, etc.) were performed to evaluate longevity, fecundity and mechanisms of vertical pathogen transmission. Larvae and adults were infected in all spore treatments. Larval growth was significantly reduced at dosages above 10 spores/larva. Adults infected at all dosages experienced high levels of mortality and fecundity was reduced to zero. Greenhouse trials were performed to determine if larvae feeding in soil acquired infections when spores were topically applied as a drench application (0, 10⁵, 10⁶, 10⁷ spores/pot). Established larvae feeding on plant roots in pots developed infections when exposed to drench treatments of 10⁶ and 10⁷ spores/pot after 14-21 days. Canningia sp. is an acute pathogen of O. sulcatus infective to both larvae and adults. Topically applied spores also infected larvae feeding on roots in soilless potting media, suggesting the possibility of using this pathogen in a microbial control program.     

First report of fern (Culcita macrocarpa) spore consumption by a small mammal (Apodemus sylvaticus)

Few vertebrates are known to consume ferns regularly. Several species of mammals consume leaves to some extent but the consumption of fern spores is much rare. In Galicia (Northwest Spain) we studied the seasonal variation in the consumption of Culcita macrocarpa fertile leaves (i.e. with spores) in two populations (Capelada and Eume), assessed whether consumption rate increased with fern population size, and evaluated whether the consumer was a spore predator or a spore disperser. Consumption began in December and finished by mid February, and occurred before spore release, which happened later in Capelada than in Eume, probably influenced by differences in altitude. The consumer was identified as Apodemus sylvaticus by DNA analysis of its droppings and by capture of live animals. Throughout Galicia there was a significant increase in fern consumption rate as the population size of C. macrocarpa increased. Germination tests from droppings were carried out in 14 dishes but only in two dishes 1% and 0.3% of the spores germinated. Our results suggest that woodmouse can disperse spores of C. macrocarpa, although most of the spores were digested.     

Development,Distribution, and Host Studies of the Fungus Macrobiotophthoira vermicola (Entomophthorales)

The life cycle and host range of Macrobiotophthora vermicola were studied. Secondary spores produced from forcibly ejected primary spores adhered to the cuticle of Cruznema tripartitum, germinated, and penetrated the cuticle within 30 minutes. New primary spores were produced within 24 hours of initial spore adhesion. In a host range study, species of Rhabditidae, Diplogasteridae, and Aphelenchoidea were hosts, but not species of Bunonematidae, Tripylidae, Cephalobida, or Tylenchina. Numbers of second-stage Meloidogyne incognita juveniles were not decreased when added to soil seeded with infected C. tripartitum. In six Tennessee soybean fields, Macrobiotophthora vermicola was the most commonly encountered nematode-destroying fungus, followed by a sterile, nonseptate fungus and Arthrobotrys conoides. Nematophagous fungi were isolated more frequently from silt loam soils than from clay soils. Addition of C. tripartitum to soil extract plates as a bait nematode did not increase isolations of nematophagous fungi.     

Amyloidity is not diagnostic for species in the Mycena pearsoniana complex (Mycena sectio Calodontes)

In Mycena sectio Calodontes with otherwise amyloid spores, the inamyloid spores of Mycena pearsoniana Dennis ex Singer were a distinguishing feature for this species and its subsection Violacella. Although the original concept of this species was European, Singer chose to typify it with material collected in Mexico. The name has since been applied to all European collections with inamyloid spores and decurrent lamellae. Our phylogenetic analysis of 91 ITS sequences from European, North and South American Calodontes collections shows that European collections identified as M. pearsoniana fall into two well-supported sibling clades together with both inamyloid and weakly amyloid North American collections. Since the holotype of M. pearsoniana is in an advanced state of decay, we have selected an epitype from a North American locality with a climate comparable to the Mexican type locality. Our results show weakly and inamyloid spore reactions to be homoplastic in Calodontes, and furthermore that spores of M. pearsoniana can show either amyloid or inamyloid reactions interchangeably. This raises doubt about the taxonomic value of this trait in Mycena systematics.     

A new record of Myxobolus brachysporus and M. israelensis in the tilapia (Oreochromis niloticus) collected from the Nile River,Egypt

The present study was carried out as part of an ongoing general survey for myxosporean parasites infecting tilapias in the River Nile, Egypt. In the present study, 77 Nile tilapia (Oreochromis niloticus) were collected from boat landing sites at Beni-Suef governorate, Egypt and examined for the myxosporean infection. The infection was encountered as a huge number of free spores in the kidney and the spleen. The infection showed a prevalence of 51.9% (40/77) for Myxobolus brachysporus while it was 25.9% (20/77) for Myxobolus israelensis. Mature spores of M. brachysporus were ellipsoidal and measured 8.6 × 13.2 μm. The polar capsules were subcircular with 5–6 filament turns and measured 4.7 × 3.6 μm. Spores of M. israelensis were ellipsoidal in the frontal view and fusiform in the lateral view. Spore measurements were 13.4 μm long and 8.7 μm wide. The polar capsules were elongated with 6–7 filament coils and measured 8.6 × 3.1 μm. The findings presented here proved that tilapia fishes in the Nile River are still suffering from infections with Myxobolus species. Therefore, further studies should be carried out to survey the Myxobolus infection among tilapias under culture conditions to clarify the pathological impacts of this parasite in tilapias aquaculture.     

Impact of Vairimorpha necatrix and Vairimorpha sp. (Microspora: Microsporida) on Bonnetia comta (Diptera: Tachinidae) within Agrotis ipsilon (Lepidoptera: Noctuidae) hosts

The effect of Vairimorpha necatrix and Vairimorpha sp. on Bonnetia comta developing within pathogen-treated black cutworm, Agrotis ipsilon, hosts was studied. Parasitism by B. comta did not interfere with the near 100% mortality of A. ipsilon caused by either Vairimorpha species. Both microsporidia decreased the number of B. comta able to pupate from a. ipsilon hosts, the days required for adult parasitoid eclosion, and the weights of the puparia. Only in the V. necatrix treatments, however, were these effects significant (P < 0.05) as determined by Duncan's (1955) multiple range test. The impact of each microsporidium on the parasitoid increased with an increase in the concentration of spores to which A. ipsilon was exposed. Both Vairimorpha species had a more detrimental effect on female B. comta than they did on male B. comta. Histological examination of B. comta maggots within V. necatrix- and Vairimorpha sp.-infected A. ipsilon showed the spores primarily restricted to the gut lumen. In older B. comta, dissected from dead Vairimorpha-infected hosts, the guts containing spores were much distended, some to the point that most other parasitoid tissues were absent. This suggests that the detrimental impact the host microsporidian infections had on the parasitoid were related to a nutritional deficiency caused by the accumulation of nondigestable spores in the parasitoid's gut lumen.     

Contributions to the knowledge of the Caytoniales

Some additional features of the caytonialean capsule are described and the conventional interpretation of the “mouth” is challenged. The Caytonanthus pollen grains examined in the light and scanning electron microscope show a bilobed equatorial saccus sculptured with endosexinous ridges. The caytonialean seeds and androclads (Caytonanthus tyrmensis sp. nov.) from the uppermost Jurassic—lowermost Cretaceous Tyrma locality (Far East of the U.S.S.R.) are closely comparable with the corresponding organs of their Middle Jurassic predecessors showing striking evolutionary conservatism. However, the evolutionary potentials of the Caytoniales must not be understood. The caytonialean monandra and monogyna are considered as the nearest approach to angiosperm stamens and pistils.