Two new and one already known species of the genus Thelohanellus (Myxozoa: Myxosporea: Bivalvulida) parasitizing fresh water fishes in wetlands of Punjab, India

A study of parasites of freshwater fishes in Harike and Ropar wetlands of Punjab of India revealed the presence of two new and one already known myxozoan species belonging to the genus Thelohanellus Kudo, 1933 infecting gills and caudal fin of two carps and gall bladder of a catfish in the wetlands of Punjab, India. Plasmodia of the first species, T. lamelliformis sp. n. are found infecting primary gill lamellae of Catla catla (Hamilton, 1822) vern. thail, spores measure 10.27 × 4.9 μm, are elongate pyriform, tapering anteriorly in valvular view, having truncated anterior end and broad rounded posterior end. Shell valves are stained dark blue (with iron-haematoxylin) in the middle as well as in the posterior part of the spore body. Anteriorly, a prominent bent is present on one side of the shell valve. Polar capsule is broadly pyriform, measures 3.8 × 2.6 μm and is placed in the middle of spore body cavity with a distinct neck leading to the outside. Plasmodia of the second species, T. rohi sp. n. are found infecting caudal fin of Labeo rohita (Hamilton, 1822) vern. rohu, spores measure 14.5 × 7.7 μm, are elongately oval in valvular view having narrow, blunt anterior end with a prominent pore and broad rounded posterior end. A knob-like structure is present at the anterior end of the spore. Inner valve stains dark-blue (with iron-haematoxylin) in the middle and posterior part of the spore body. Polar capsule is oval to spherical in shape, measures 5.5 × 4.7 μm, is placed anteriorly and occupies nearly one third of the spore body cavity. Plasmodia of the third species, T. wallagoi Sarkar, 1985 infect primary gill lamellae of Wallago attu (Bloch & Schneider, 1807), spores measure 8.2 × 4.1 μm, are pyriform in valvular view, having bluntly pointed anterior end and rounded posterior end. Parietal folds are absent. Polar capsule is pyriform, measures 3.3 × 1.67 μm, is eccentrically placed with narrow pointed anterior end. Earlier, this species was reported from West Bengal infecting gall bladder of Wallago attu.

The walk and jump of Equisetum spores

Equisetum plants (horsetails) reproduce by producing tiny spherical spores that are typically 50 µm in diameter. The spores have four elaters, which are flexible ribbon-like appendages that are initially wrapped around the main spore body and that deploy upon drying or fold back in humid air. If elaters are believed to help dispersal, the exact mechanism for spore motion remains unclear in the literature. In this manuscript, we present observations of the ‘walks’ and ‘jumps’ of Equisetum spores, which are novel types of spore locomotion mechanisms compared to the ones of other spores. Walks are driven by humidity cycles, each cycle inducing a small step in a random direction. The dispersal range from the walk is limited, but the walk provides key steps to either exit the sporangium or to reorient and refold. Jumps occur when the spores suddenly thrust themselves after being tightly folded. They result in a very efficient dispersal: even spores jumping from the ground can catch the wind again, whereas non-jumping spores stay on the ground. The understanding of these movements, which are solely driven by humidity variations, conveys biomimetic inspiration for a new class of self-propelled objects.

Spore ornamentation of Haplosporidium hinei n. sp. (Haplosporidia) in pearl oysters Pinctada maxima (Jameson, 1901)

SUMMARYAn infection of pearl oysters, Pinctada maxima, attributed to a Haplosporidium sp. by Hine and Thorne (1998) has been detected on 3 occasions and is considered to represent a serious concern to the pearling industry in Australia. The spore ornamentation of the parasite was determined by scanning electron microscopy and transmission electron microscopy. Spores of the parasite were pleomorphic, or elongated 3·5–4 μm×2·5–3·0 μm in size. Two filaments were wound around the spore and originated from 2 ‘knob-like’ posterior thickenings. Both filaments passed up one side of the spore together until just below the operculum whereupon each split and passed obliquely under the lip of the opercula lid. Each filament wrapped around the spore 4 times. The posterior thickenings seem to appear late in the development of the spore and were composed of spore wall material. A second set of branching tubular filaments composed of a different material was observed on the spore body although not on mature spores possessing a ‘knob-like’ posterior thickening. The ornamentation on the spores of the pearl oyster parasite was unique amongst described haplosporidian species where spore ornamentation is known. The parasite is named in this manuscript as Haplosporidium hinei n. sp.

Light and electron microscopic study of the myxosporean, Henneguya friderici n. sp. from the Amazonian teleostean fish, Leporinus friderici

A new histozoic species of myxosporean was found to infect the gill filaments, gut, kidney and liver of the freshwater teleost Leporinus friderici, collected from the estuarine region of the Amazon, near the city of Belém, Brazil. The plasmodia show asynchronous development, at any one time composed of mature spores and all sporogonic stages. The ellipsoidal spore body, measuring 10·4 μm long and 5·7 μm wide, consists of 2 equal shell valves adhering together along the straight suture line. Each valve has a caudal process measuring 23·3 μm in length. There are 2 symmetric polar capsules, without intercapsular appendix, measuring 5·0 μm×2·1 μm, and each has a polar filament with 7–8 coils. In general, ultrastructural details of sporoblast and spore development are in agreement with previously described myxosporeans. Some ultrastructural aspects such as cellular alterations of the pericyte in the different organs infected and characterization of the sporoplasmosomes during the sporoplasm maturation are described. This parasite was studied under light and electron microscope and compared with others species of the genus Henneguya, considering also host specificity. From our observations we propose the creation of a new species, Henneguya friderici n. sp.

Outbreak of Leaf Spot of Saponaria Caused by Alternaria saponariae in California

Saponaria (Saponaria vaccaria [= Vaccaria hispanica]) is a Caryophyllaceae plant that is grown commercially in California as a cut flower. In 1998, a leaf spot disease devastated the commercially grown saponaria in coastal California. The entire saponaria crop was completely unmarketable because of extensive leaf spotting. Symptoms consisted of circular, brown, necrotic leaf spots with diameters up to 8 mm and concentric zones of lighter and darker tissue. Chlorotic borders developed around the spots. Conidia from leaves were obclavate, usually had 7 transverse and 1 to 4 longitudinal septa, and narrowed gradually toward the apex into a blunt-tipped, unbranched beak cell. The spore body measured 69 to 90 (to 119) × 17 to 21 (to 25) μm, with the distinctive beak cell 17 to 53 μm long. Conidia formed short chains on host tissue. The fungus was identified as Alternaria saponariae (Peck) Neergaard (2). For pathogenicity tests, six representative isolates were grown on V8 juice agar under fluorescent tube lighting. Potted saponaria were sprayed with either conidial concentrations (1 × 10e5 conidia per ml) or water. Plants were incubated in a chamber with a humidifier for 48 h and then maintained in a greenhouse (23 to 25°C). After 14 days, leaf spots similar to the original symptoms developed on all inoculated plants, and the pathogen was reisolated. Plants sprayed with water were symptomless. The experiment was repeated and the results were similar. Using the same isolates and method, we inoculated carnation (Dianthus caryophyllus), sweet William (Dianthus barbatus), and saponaria. However, disease developed only on saponaria. While A. saponariae on saponaria was reported previously in California (1), this is the first report to characterize the pathogen and document that isolates are pathogenic on saponaria but not on other commercial Caryophyllaceae hosts. References: (1) K. F. Baker and L. H. Davis. Plant Dis. Rep. 34:403, 1950. (2) P. Neergaard. Aarsberet. J. E. Ohlsens Enkes Plantepat. Lab. No. 3, 1938.

Purple Blotch, Caused by Alternaria porri, on Leek Transplants in California

In 1997, a foliar disease was detected on leek (Allium porrum) grown as transplants in California greenhouses. Initial symptoms consisted of small (less than 5 mm in diameter), circular, white leaf spots. Spots later enlarged, and became elliptical to oblong in shape and purple with tan borders in color. When spots coalesced, the leaf tips desiccated and wilted. Singly borne, brown conidia from leaves were obclavate in shape with slender, unbranched beaks extending from the narrow end of the spore body. Spore body dimensions measured 81 to 120 (96 mean) µm × 14 to 19 (16 mean) µm, and beaks measured 11 to 56 (30 mean) µm × 3 to 6 (4 mean) µm. Spore bodies had 6 to 9 transverse septa and occasionally 1 longitudinal septum. The fungus was identified as Alternaria porri (Ellis) Cif. (1). The same fungus was also consistently isolated from the margins of the spots. For pathogenicity tests, isolates were grown for 6 weeks on potato dextrose agar under a combination of one cool white and one Vita-Lite fluorescent tube on a 12 h light/dark cycle. Conidial suspensions (1.0 × 10 e 4 conidia/ml) were sprayed onto 2-month-old leek (cvs. Broad London and Gavilan). Plants were incubated in a moist chamber for 48 h and then kept in a greenhouse. After 14 days, leaf spots similar to the original symptoms developed on inoculated plants, and the pathogen was reisolated. Control plants sprayed with distilled water remained symptomless. The experiment was repeated and the results were similar. The isolates also caused leaf spots on onion (Allium cepa cv. Stockton Early Yellow) and chives (Allium schoenoprasum). This is the first report of purple blotch caused by A. porri on commercially grown leeks in California. The occurrence of this disease on leeks in enclosed greenhouses strongly suggested that the primary inoculum was seed-borne. Reference: (1) M. B. Ellis and P. Holliday. C.M.I. Descriptions No. 248, 1970.

Leaf Spot of Radicchio Caused by Alternaria cichorii in California

A foliar disease of commercially grown radicchio (Cichorium intybus) was observed in 1996 and 1997 in the Salinas Valley (Monterey County), California. Symptoms consisted of circular to oblong, necrotic spots ranging in diameter from 3 to 20 mm and having concentric zones of darker tissue. A fungus identified as Alternaria cichorii Nattrass (1) was observed fruiting on the spots and was consistently isolated from the margins of the spots. Conidia from leaves were obclavate in shape with slender, unbranched beaks extending from the narrow end of the spore body. Spore body dimensions measured 56 to 78 × 14 to 20 μm, and beaks measured 36 to 81 × 1 to 2 μm. Spore bodies had 7 to 9 transverse septa. Often there were no longitudinal septa, but occasionally there were 1 or 2 such septa. For pathogenicity tests, five isolates were grown for 4 weeks on potato dextrose agar under a combination of cool white and Vita-Lite fluorescent tubes on a 12 h light/dark cycle. Conidial suspensions (4.0 × 104 conidia per ml) were sprayed onto 8-week-old radicchio (cv. Rossana Rogers). Plants were incubated in a moist chamber for 48 h and then maintained in a greenhouse. After 12 days, leaf spots similar to the original symptoms developed on all plants inoculated with the five isolates, and the pathogen was reisolated. Control plants sprayed with distilled water remained symptomless. The experiment was repeated and the results were similar. When inoculated onto endive (Cichorium endivia cv. Tres Fine Maraicchere) and two lettuce (Lactuca sativa) cultivars, the isolates caused small (1 to 2 mm in diameter), necrotic, circular leaf spots on endive and Romaine lettuce cv. Green Towers, but did not cause symptoms on the iceberg lettuce cv. Alpha. This is the first report of A. cichorii on commercially grown radicchio in California. In addition, the same disease was confirmed on commercially produced greenhouse transplants of radicchio, indicating that primary inoculum can possibly be seed-borne. Reference: (1) J. C. David. Mycopathologia 129:41, 1995.

The zoospore of Schizochytrium aggregatum

The zoospore ultrastructure of the marine protist Schizochytrium aggregatum was examined in detail. The zoospores of S. aggregatum differed considerably from the zoospores of the presumably closely related marine protist Thraustochytrium. The flagella of S. aggregatum emerged from an erumpent area and followed along shallow grooves on the spore body. The mastigonemes of the anterior flagellum are localized along one-third the circumference of the flagellar shaft. There is a concertina-like structure just distal to the kinetosome terminal plate and osmiophilic granules are present within the kinetosome lumen. Microtubular bundles are associated with the kinetosomes and form a "backbone root" system. Serial reconstructions show that each zoospore contains a single tubular mitochondrion. Closely associated with the mitochondrion is a single microbody which in turn is appressed to the nuclear membrane. The ultrastructural data suggest that Schizochytrium aggregatum can be accommodated among the Fungi.

Ultrastructural studies on Orbilia luteorubella (Discomycetes)

Transmission electron microscopic observations made on the ascus tip of Orbilia luteorubella showed that it is truncate and that the outer ascus wall is relatively thicker at the shoulders than on the top or sides. There is no demonstrable discharge mechanism in the ascal apex of this fungus comparable with that found in the ascus tip of other supposedly related inoperculate Discomycetes, including Mollisia cinerea.Ascospores of O. luteorubella contain a single, electron-opaque spore body that appears to evolve from a mitochondrion that is attached, at one end, to the inner wall of the spore apiculus. The function of the spore body is unknown.A blue-green alga, probably of the genus Anacystis, is associated with this and at least one other Orbilia species. Since these Orbilia species are here shown to be lichenized and they do not have an ascal pore discharge mechanism, the transfer of these fungi from the Helotiales is proposed. They can probably best be treated as lichens of uncertain affinities, perhaps related to those members of Lecanorales with iodine-negative asci.

Cytology of Rosellinia mammiformis and R. aquila

The chromosome number of Rosellinia mammiformis is n = 6. Ascospores are uninucleate when formed, becoming binucleate by mitosis. One of the nuclei degenerates; maturing ascospores are uninucleate. Ascospores show apical appendages that are proliferations of the outermost wall or perispore. The chromosome number of Rosellinia aquila is tentatively n = 6. Ascospores are at first uninucleate, becoming binucleate by a mitosis. One of the nuclei degenerates and is often cut off in an appendage. Maturing ascospores are uninucleate and show two types of appendages. Secondary appendages are formed from the perispore. Primary appendages are cut off from the spore body by a septum and are surrounded by the secondary appendage. In addition, a double primary appendage, part of which probably functions to trap a degenerating nucleus, is described. The significance of these results is discussed.