Microkamienskia gen. nov. and Microkamienskia peruviana, a new arbuscular mycorrhizal fungus from Western Amazonia

A new arbuscular mycorrhizal (AM) fungus, Microkamienskia peruviana, was detected in bait cultures for arbuscular mycorrhizal fungi established with rhizospheric soil substrates of the inka nut (Plukenetia volubilis). The field soil derived from three agricultural plantations in the Amazonia lowlands of the province Lamas, San Martin State, in Peru. The fungus was subsequently propagated in single species cultures on Sorghum sp., Brachiaria sp.,Medicago sativa and P. volubilis as host plants. The new species differentiates hyaline spores regularly in spore clusters, up to 500–800×400–600 μm. The spores are 16–31(–36)×13–29(–35) μm in diam, formed on cylindrical or slightly funnel-shaped hyphae, without a septum at or close to the spore base. Phylogenetically, the new fungus belongs to a new genus, named Microkamienskia, which has as type species M. perpusilla comb. nov. and to which also M. divaricata comb. nov. belongs. Both are transferred from Kamienskia to Microkamienskia in the present study. The new fungus can be identified by the ballooning semi-persistent to evanescent outer spore wall layer in PVLG-based mountants that is not known for the other species of these two genera, nor for any other glomeromycotan species of similar small spore sizes. Kamienskia and Microkamienskia species can be distinguished by their position in the phylogenetic tree and by hyaline spores, open pores at the spore bases and in the subtending hyphae, and by their spore sizes that are for Microkamienskia among the smallest spore sizes so far detected for AM fungi (15–35 μm).

Fingerprinting of Secondary Metabolites of Liverworts: Chemosystematic Approach

The relationship between various types of plants can be predicted based on the similarity in the chemical substances present in them. Compounds that belong to the category of secondary metabolites are of great value in identifying such relationships. Additionally, results from the chemical investigations, together with the other biological or genetic information, can help to understand real relationships among the taxa. Liverworts are small spore-forming plants with simple morphological organization. On the other hand, many liverwort species demonstrate wide geographical distribution and grow under diverse ecological conditions. Because of this, the identification of these plants is especially challenging. One of the outstanding features of the liverworts is their chemistry. They produce a wide array of secondary metabolites, mainly terpenoids and aromatic compounds. Many of these compounds are characterized by unique structures, and some have not been found in any other plants, fungi, or marine organisms. The potential use of chromatographic fingerprinting of the liverworts, as complementary to morphological and genetic information, to resolve the taxonomic problems at the species, genus, and family levels are discussed.

Cytometric Approach for Detection of Encephalitozoon intestinalis, an Emergent Agent

ABSTRACT Encephalitozoon intestinalis is responsible for intestinal disease in patients with AIDS and immunocompetent patients. The infectious form is a small spore that is resistant to water treatment procedures. Its detection is very important, but detection is very cumbersome and time-consuming. Our main objective was to develop and optimize a specific flow cytometric (FC) protocol for the detection of E. intestinalis in hospital tap water and human feces. To determine the optimal specific antibody (Microspor-FA) concentration, a known concentration of E. intestinalis spores (Waterborne, Inc.) was suspended in hospital tap water and stool specimens with different concentrations of Microspor-FA, and the tap water and stool specimens were incubated under different conditions. The sensitivity limit and specificity were also evaluated. To study spore infectivity, double staining with propidium iodide (PI) and Microspor-FA was undertaken. Distinct approaches for filtration and centrifugation of the stool specimens were used. E. intestinalis spores stained with 10 μg/ml of Microspor-FA at 25°C overnight provided the best results. The detection limit was 5 × 104 spores/ml, and good specificity was demonstrated. Simultaneous staining with Microspor-FA and PI ensured that the E. intestinalis spores were dead and therefore noninfectious. With the stool specimens, better spore recovery was observed with a saturated solution of NaCl and centrifugation at 1,500 × g for 15 min. A new approach for the detection of E. intestinalis from tap water or human feces that ensures that the spores are not viable is now available and represents an important step for the prevention of this threat to public health.

Evidence that the Dictyostelium Dd-STATa protein is a repressor that regulates commitment to stalk cell differentiation and is also required for efficient chemotaxis

Dd-STATa is a structural and functional homologue of the metazoan STAT (Signal Transducer and Activator of Transcription) proteins. We show that Dd-STATa null cells exhibit several distinct developmental phenotypes. The aggregation of Dd-STATa null cells is delayed and they chemotax slowly to a cyclic AMP source, suggesting a role for Dd-STATa in these early processes. In Dd-STATa null strains, slug-like structures are formed but they have an aberrant pattern of gene expression. In such slugs, ecmB/lacZ, a marker that is normally specific for cells on the stalk cell differentiation pathway, is expressed throughout the prestalk region. Stalk cell differentiation in Dictyostelium has been proposed to be under negative control, mediated by repressor elements present in the promoters of stalk cell-specific genes. Dd-STATa binds these repressor elements in vitro and the ectopic expression of ecmB/lacZ in the null strain provides in vivo evidence that Dd-STATa is the repressor protein that regulates commitment to stalk cell differentiation. Dd-STATa null cells display aberrant behavior in a monolayer assay wherein stalk cell differentiation is induced using the stalk cell morphogen DIF. The ecmB gene, a general marker for stalk cell differentiation, is greatly overinduced by DIF in Dd-STATa null cells. Also, Dd-STATa null cells are hypersensitive to DIF for expression of ST/lacZ, a marker for the earliest stages in the differentiation of one of the stalk cell sub-types. We suggest that both these manifestations of DIF hypersensitivity in the null strain result from the balance between activation and repression of the promoter elements being tipped in favor of activation when the repressor is absent. Paradoxically, although Dd-STATa null cells are hypersensitive to the inducing effects of DIF and readily form stalk cells in monolayer assay, the Dd-STATa null cells show little or no terminal stalk cell differentiation within the slug. Dd-STATa null slugs remain developmentally arrested for several days before forming very small spore masses supported by a column of apparently undifferentiated cells. Thus, complete stalk cell differentiation appears to require at least two events: a commitment step, whereby the repression exerted by Dd-STATa is lifted, and a second step that is blocked in a Dd-STATa null organism. This latter step may involve extracellular cAMP, a known repressor of stalk cell differentiation, because Dd-STATa null cells are abnormally sensitive to the inhibitory effects of extracellular cyclic AMP.

Pyrrhoglossum and the small-spored species of Gymnopilus (Cortinariaceae) in eastern Australia

Three new species of Gymnopilus subgenusGymnopilus section Microspori aredescribed from eastern Australia. These areGymnopilus marginatus,Gymnopilus patriae andGymnopilus parvisporus. Because of their frequently excentrically stipitate habit and small spore size, the species are comparedwith Pyrrhoglossum pyrrhum (Berk. & M.A.Curtis)Singer, the type species of the genus Pyrrhoglossum,whose presence is also recorded from Australia for the first time. Pigment content of all four species has been examined by thin layer chromatography.Styrylpyrone pigments bis-noryangonin and hispidin were detected in only two of the three Gymnopilus species.Although yellow pigment can be extracted fromPyrrhoglossum pyrrhum, it does not containbis-noryangonin or hispidin.

Upper Devonian miospores from the Escuminac Formation, eastern Québec, Canada

Miospores of early Frasnian age are described from the third unit of the Escuminac Formation in eastern Québec, Canada. The assemblage comprises 34 species, including 8 species proposed as new, 2 new combinations, and 12 sparsely represented forms not considered synonymous with previously described species.The assemblage is most closely comparable to a Middle Devonian assemblage from the Orcadian Basin, Scotland. Similarities are also noted with European and Russian assemblages, particularly from the Eifelian–Givetian of the Russian Platform. Except for five long-ranging species, elements of Lower Carboniferous assemblages are lacking. Evidence suggests a transitional nature for this Escuminac assemblage. Miospores of relatively large size, a feature of Middle Devonian assemblages, are present. Marked differentiation of large and small spore types, found in several other Upper Devonian assem blages is absent. Apiculate and anchor-spined species dominate the Escuminac assemblage.