Morphology and development of the reticuloperidial ascomata of Auxarthron conjugatum

Abstract

Light and electron microscopy showed that the reticuloperidium of thick-walled hyphae, characteristic of the mature ascoma of Auxarthron conjugaturn, originated from branches that grew from the broad, gyre-like hyphal loops making up the ascomatal initials. Within the developing peridium, short, acropetally proliferating chains of prototunicate asci each arose from a single crozier and matured from base to tip. The walls of young asci were two-layered but evanesced as they matured with the outer layer dissolving before the inner one. Distal asci in some chains retained the inner wall, detached from adjacent asci by septum schizolysis and when transferred to fresh media produced germ tubes and mycelium. Ultraviolet epifluorescent staining with a DNA intercalator (Hoechst) indicated that these spore-like asci probably contained diploid nuclei. In normal asci, ascospores had an inner, electron lucent primary wall and a three-layered secondary wall. The deposition pattern of the middle layer of the secondary wall created the distinctive array of pits and ridges characteristic of the ascospores in this taxon. The production of ascospores, spore-like asci and arthroconidia, along with the tendency of ascospores to adhere in a mass, is interpreted as contributing to the reproductive flexibility and inoculum potential of A. conjugatum. In all respects the ascomata of A. conjugatum differed substantially from the morphologically similar taxon, Myxotrichum arcticum. These findings underscore the benefit of using DNA-based phylogenies in concert with cytological and ultrastructural observations for exploring selective pressures behind homoplasious characters and revealing novel structural features.

Anti-Cryptococcus Phenalenones and Cyclic Tetrapeptides from Auxarthron pseudauxarthron

“…12−15 Their sexual spores are formed within a spiny, cage-like hyphal structure called the reticuloperidium, which is thought to cling to arthropods and other animals to facilitate spore dispersal. 14,16 The fermentation was subsequently scaled up to enable separation and identification of the components responsible for the antifungal activity. NMR data for auxarthrone A (1) consistently showed two sets of signals.…”

“…On the basis of morphological features on the natural substratum of rabbit dung, features in culture, and sequences of rDNA, strain TTI-0363 was identified as Auxarthron pseudoauxarthon . Fungi of the genus Auxarthron are typically associated with dung, soils, and keratinaceous parts of animals, e.g., hair, skin, and hooves, and occasionally have been isolated from humans. − Their sexual spores are formed within a spiny, cage-like hyphal structure called the reticuloperidium, which is thought to cling to arthropods and other animals to facilitate spore dispersal. , The fermentation was subsequently scaled up to enable separation and identification of the components responsible for the antifungal activity.…”

A comparative study of Neogymnomyces virgineus, a new keratinolytic species from dung, and its relationships with the Onygenales

“…Auxarthron and Pectinotrichum share with Neogymnomyces globose gymnothecial ascomata (brightly pigmented in the former) of thick-walled hyphae which, however, are typically enlarged at the septa and support long straight or uncinate appendages in Auxarthron, comb-like appendages in Pectinotrichum. Spherical, or sometimes oblate, reticulate, hyaline ascospores (Currah 1985;Solé et al 2002a, c;Skinner et al 2006), and a Malbranchea anamorph (Sugiyama and Mikawa 2001;Sigler et al 2002a) further distinguish Auxarthron, and globose to ovoid, apparently smooth ascospores characterise Pectinotrichum (Currah 1985;Sugiyama et al 1999;Solé et al 2002a, b, c). Amauroascus differs even more from Neogymnomyces in having a telaperidium, pitted-reticulate or rarely knobbed ascospores, and sometimes a Malbranchea anamorph (von Arx 1971(von Arx , 1987Solé et al 2002a).…”