Appendage Ontogeny Research Articles

Ontogeny and Function of the Fifth Limb in Cypridocopain Ostracods

The exoskeleton of arthropods undergoes reformation at every molting. Accordingly, external morphology can metamorphose through molting. In some crustaceans, the function of appendages is modified through ontogeny. These morphological modifications require accordant modification of the correlation between different body parts because the morphological function depends on the combined correlation between different parts. In the case of crustacean morphology, exoskeleton and muscles are correlated to each other. The functional morphology of the fifth limb of cypridoid ostracods transforms from "walking leg + mouthparts (+ possibly respiratory parts)" to "mouthparts + respiratory parts + grasping hook (in males only)" through ontogeny. In this study, the three-dimensional structures of the exoskeleton and muscular systems were observed by confocal laser-scanning microscopy in some species of suborder Cypridocopina. The muscular system is reportedly not changed by the ontogeny of appendages in females, but it does change in males. Furthermore, regional cell proliferation, which was detected previously, represented the causal factor of exoskeletal modification. I therefore conclude that the enlarged endite in the female fifth limb is produced by exoskeletal modification based on regional cell proliferation, rather than by a change in the muscular system. In contrast, modification in the male requires a change in the muscular system in addition to exoskeletal modification.

Molecular and ultrastructural characterization of two ascomycetes found on sunken wood off Vanuatu Islands in the deep Pacific Ocean

A new genus of a deep-sea ascomycete with one new species, Alisea longicolla, is described based on analyses of 18S and 28S rDNA sequences and morphological characters. A. longicolla was found together with Oceanitis scuticella, on small twigs and sugar cane debris trawled from the bottom of the Pacific Ocean off Vanuatu Islands. Molecular and morphological characters indicate that both fungi are members of Halosphaeriaceae. Within this family, O. scuticella is phylogenetically related to Ascosalsum and shares similar ascospore morphology and appendage ontogeny. The genus Ascosalsum is considered congeneric with Oceanitis and Ascosalsum cincinnatulum, Ascosalsum unicaudatum and Ascosalsum viscidulum are transferred to Oceanitis, an earlier generic name.

Ultrastructure of conidiogenesis and appendage ontogeny in the coelomyceteBartalinia robillardoides

Conidiogenesis and conidial appendage ontogeny of the coelomycete Bartalinia robillardoides Tassi was studied at the light microscope, scanning electron microscope, and transmission electron microscope levels. Conidiogenesis in B. robillardoides is holoblastic. Appendage ontogeny begins as a cellular outgrowth of the apical and the basal cells of the young conidium, the former developing prior to the basal appendage. Conidia detach from the conidiogenous cells schizolytically. Mature conidial cell walls comprise two layers: an outer electron-dense layer, 30–38 nm, and an inner less electron-dense layer, 100–125 nm. The apical appendages arise from an outgrowth of the apical cell, which then branches to form the appendages. The single basal appendage arises from the junction between the basal cell of the conidium and the conidiogenous cell prior to conidial detachment from the conidiogenous cell, as an outgrowth of the conidial cell wall. Conidial appendage ontogeny is compared with those of other coelomycetes.Key words: Annellidic, appendage ontogeny, coelomycetes, holoblastic.

Ultrastructure of ascus and ascospore appendages of the mangrove fungus Halosarpheia ratnagiriensis (Halosphaeriales, Ascomycota)

Halosarpheia Kohlm. et E. Kohlm is a genus of eighteen species, all of which have septate ascospores with unfurling polar appendages. Asci and ascospores of Halosarpheia ratnagiriensis Patil et Borse were examined at the scanning (including freeze-fracture) and transmission electron microscope levels. The ascus wall has two well-defined layers and the apical apparatus comprises a refractive, electron-dense, lens-shaped disk embedded within a less electron-dense thickening. The ascospore wall comprises an episporium and a bipartite mesosporium, and the appendages are formed by extrusion of mucilaginous material through an episporial pore field. Ascospore appendage ontogeny is compared with other genera with unfurling polar appendages: Cataractispora, Diluviocola, Tunicatispora, Tirispora, and Halosarpheia aquadulcis Hsieh, H.S. Chang et E.B.G. Jones and Halosarpheia heteroguttulata S.W. Wong, K.D. Hyde et E.B.G. Jones.Key Words: ascospore appendage ontogeny, marine ascomycetes, unfurling polar appendages, ultrastructure.

Cataractispora gen. nov. with three new freshwater lignicolous species

A new genus of freshwater ascomycetes, Cataractisopora, with three new species: C. aquatica, C. appendiculata and C. viscosa, are described. These fungi occur on decaying wood and possess similar characteristics including coriaceous globose ascomata, wide septate paraphyses, cylindrical asci with a relatively massive refractive apical ring and ascospores with polar chambers and filamentous appendages. Appendage material accumulates within the polar chambers and, on release from the ascus, the ascospore appendage unfurls to form long threads. The appendage material is fibrillar at the ultrastructural level, and is derived from episporial projections at the ascospore tip. Although these three fungi are similar to species of Annulatascus, they are assigned to a new genus – Cataractispora based on their unique appendage ontogeny. Annulatascus bipolaris is also assigned to Cataractispora on the basis of its ascospore appendage ontogeny.

Lignicolous freshwater Ascomycota from Thailand: Micropeltopsis quinquecladiopsis sp. nov.

A new freshwater ascomycete Micropeltopsis quinquecladiopsis sp. nov. was collected on submerged twigs in a stream in Thailand. The fungus is described at the light microscope, scanning and transmission electron microscope level. Distinctive features are the appendaged 1-septate hyaline ascospores. The appendage arises as an outgrowth of the episporium from a basal stalk, then divides into five arms (three long and two short). The episporium and appendages are surrounded by an indistinct (at light microscope level) mucilaginous layer. The fungus is assigned to the Dothideales (Trichothyriaceae). Ascospore appendage ontogeny is compared with those of marine Ascomycota (Halosphaeriales).

Halosarpheia heteroguttulata sp.nov. from submerged wood in streams

A new species of Halosarpheia, H. heteroguttulata, is described from wood submerged in streams and lakes in Australia, Brunei, Hong Kong, Mauritius, the Philippines, and South Africa. It differs from other species in the genus in ascospore dimensions, and consistently large guttule(s) in the apical cell, but many smaller guttules in the basal cell. The species is illustrated with light and scanning and transmission electron micrographs and compared with other Halosarpheia species.Key words: appendage ontogeny, freshwater Ascomycete, Halosarpheia, taxonomy, ascospore ultrastructure.

Ultrastructure and taxonomy of the aquatic ascomycetous order Halosphaeriales

The nomenclatural status of genera of the Halosphaeriaceae (Halosphaeriales, Ascomycotina) is reviewed and a key to the genera is presented. Ten types of ascospore appendage ontogeny in species of the Halosphaeriaceae have been demonstrated at the ultrastructural level and are redescribed and discussed. The family currently comprises 42 genera (with 4 new genera to be erected) with 132 species. Key words: marine Ascomycotina, ascospore appendage ontogeny, evolution, ultrastructure.

Limacospora gen.nov. and a reevaluation of Ceriosporopsis cambrensis

Fresh collections of Ceriosporopsis sundica enabled an ultrastructural study of ascospores and spore appendage ontogeny. Ascospores are surrounded by an exosporic mucilaginous sheath of variable morphology, initially "slug-shaped" but at maturity ovoid. The fibrous component of the appendage is contiguous with the mesosporium through discontinuities in the episporium. Polar appendages are extensions of the sheath and not discrete mesosporial outgrowths as characteristic of Ceriosporopsis spp. A reexamination of the type material of C. cambrensis shows that spore measurements differ from those given by an earlier researcher, as does the general morphology of the appendages. It is concluded that two species are involved and C. cambrensis must be regarded a nomen dubium. Key words: appendages, Ceriosporopsis, Halosphaeriaceae, Limacospora, taxonomy, ultrastructure.

Ascospore ultrastructure of Pleospora gaudefroyi (Pleosporaceae, Loculoascomycetes, Ascomycotina)

Ascospore and spore appendage ultrastructure in Pleospora gaudefroyi is described. Ascospore walls comprise a three-layered mesosporium within which electron-dense bodies (melanin?) are deposited in two layers (W2, W3), a tripartite episporium (W4), and an outer mucilaginous sheath (exosporium?). The electron-dense inclusions in the mesosporium are compared with those in the conidia of Alternaria brassicicola and ascospores of Carbosphaerella leptosphaerioides. In the unitunicate marine Ascomycetes, ascospores with a sheath are uncommon, whereas in the Loculoascomycetes many species have such ascospores. The sheath in P. gaudefroyi is compared with those of Paraliomyces lentiferus, Massarina thalassiae, and Massarina armatispora (all Loculoascomycetes). Key words: appendage ontogeny, marine Ascomycotina, taxonomy, ultrastructure.

Light and scanning electron microscope observations of the marine ascomycete Crinigera maritima

Light and scanning electron microscope observations of the cleistothecial appendages, asci and ascospore appendage ontogeny in Crinigera maritima are presented. Cleistothecia have short branched appendages over the entire surface and long, basally attached, unbranched hyphae. Asci are thick-walled but at maturity deliquesce to release appendaged ascospores. The inner wall layer(s) of young ascospores is surrounded by a sheath composed of two layers. Following the liberation of the ascospores, the outer layer of the sheath swells. This layer becomes more diffuse and forms ball-like structures, while the strands of the inner layer uncoil to form radiating appendages to which the ball-like structures may remain attached. The distal ends of the appendages frequently become very fibrillar and may aid in the attachment of the ascospores. Spore appendage development in C. maritima is compared with that of other marine ascomycetes.

Ontogeny of the vegetative and floral apex of Calycanthus occidentalis

The early ontogeny of the flower of Calycanthus occidentalis is described. The pattern of initiation, procambial development, apical growth, and marginal growth of floral bracts and tepals is similar to that of the leaf, while stamens, staminodia, and carpels are not leaf-like in some aspects of their development. The initiating periclinal divisions of staminodia and carpels occur in the third and fourth layers from the surface and procambium development in the carpel is discontinuous and bidirectional. These similarities in development to some axillary buds are probably due to the position of the young primordia which are isolated from developing procambial strands by parenchyma tissue. The concave floral cup is formed through the activity of an intercalary meristem concurrently with the early stages of appendage ontogeny.