Morphological characteristics of sporangiospores of the tempe fungus Rhizopus oligosporus differentiate it from other taxa of the R. microsporus group

The fungus Rhizopus oligosporus (R. microsporus var. oligosporus) is traditionally used to make tempe, a fermented food based on soybeans. Interest in the fungus has steadily increased, as it can also ferment other substrates, produce enzymes, and treat waste material. R. oligosporus belongs to the R. microsporus group consisting of morphologically similar taxa, which are associated with food fermentation, pathogenesis, or unwanted metabolite production (rhizonins and rhizoxins). The ornamentation pattern, shape, and size of sporangiospores of 26 R. microsporus group strains and two R. oryzae strains were studied using low-temperature SEM (LT-SEM) and LM. This study has shown that: (1) LT-SEM generates images from well-conserved sporangiophores, sporangia, and spores. (2) Robust spore ornamentation patterns can be linked to all different taxa of the R. microsporus group, some previously incorrectly characterized as smooth. Ornamentation included valleys and ridges running in parallel, granular plateaus, or smooth polar areas. Distribution of ornamentation patterns was related to spore shape, which either was regular, ranging from globose to ellipsoidal, or irregular. Specific differences in spore shape, size, and ornamentation were observed between Rhizopus taxa, and sometimes between strains. (3) R. oligosporus has a defect in the spore formation process, which may be related to the domesticated nature of this taxon. It had a high proportion, 10–31 %, of large and irregular spores, and was significantly differentiated from other, natural Rhizopus taxa as evaluated with partial least squares discriminant analysis. It is remarkable that the vehicle of distribution, the sporangiospore, is affected in the strains that are distributed by human activity. This provides information about the specificity and speed of changes that occur in fungal strains because of their use in (food) industry.     

Arginine vasopressin inhibition of cyclin D1 gene expression blocks the cell cycle and cell proliferation in the mouse Y1 adrenocortical tumor cell line

Arginine vasopressin (AVP) is a nonapeptide long known as an endocrine and paracrine regulator of important systemic functions, namely, vasoconstriction, gluconeogenesis, corticosteroidogenesis, and excretion of water and urea. Here we report, for the first time, that AVP specifically inhibits expression of the cyclin D1 gene, leading to cell cycle blockage and halting cell proliferation. In G0/G1-arrested mouse Y1 adrenocortical tumor cells, maintained in serum-free medium (SFM), AVP mimics FGF2, promoting rapid ERK1/2 activation (5 min) followed by c-Fos protein induction (2 h). PKC inhibitor Go6983 and PI3K inhibitors wortmannin and LY294002 all inhibit ERK1/2 activation by AVP, but not by FGF2. Thus, AVP and FGF2 concur to activate ERK1/2 by different regulatory pathways. However, AVP is not a mitogenic factor for Y1 cells. On the contrary, AVP strongly antagonizes FGF2 late induction (2-5 h) of the cyclin D1 gene, down-regulating both cyclin D1 mRNA and protein. AVP inhibition of cyclin D1 expression is sufficient to block G1 phase progression and cell entry into the S phase, monitored by BrdU nuclear labeling. In addition, AVP completely inhibits proliferation of Y1 cells in 10% fetal calf serum (10% FCS) medium. On the other hand, ectopic expression of the cyclin D1 protein renders Y1 cells resistant to AVP for both entry into the S phase in SFM and continuous proliferation in 10% FCS medium. In conclusion, inhibition of cyclin D1 expression by AVP is an efficient mechanism of cell cycle blockage and consequent proliferation inhibition in Y1 adrenocortical cells.     

Hoffmannoscypha, a novel genus of brightly coloured, cupulate Pyronemataceae closely related to Tricharina and Geopora

The rare apothecial, cupulate fungus Geopora pellita (Pyronemataceae) is characterized by a uniquely bright yellow-orange excipulum. We here re-examine its affiliations by use of morphological, molecular phylogenetic and ultrastructural analyses. G. pellita appears as phylogenetically rather isolated, being the sister group of a clade comprising Phaeangium, Picoa, the majority of the Tricharina species, and the remaining Geopora species. Based on its phylogenetic position and its unique combination of morphological characters, we assign G. pellita to Hoffmannoscypha, gen. nov., as H. pellita, comb. nov. As in a previous study, analyses of both large subunit (LSU) and internal transcribed spacer (ITS) ribosomal DNA suggest that the remaining genus Geopora is paraphyletic, with the hypogeous, ptychothecial type species more closely related to Picoa and Phaeangium than to the greyish-brownish cupulate and apothecial Geopora spp., indicating that the latter should be reassigned to the genus Sepultaria. The current study also shows that ITS confirm LSU data regarding the polyphyly of Tricharina.     

Exploration of cytoplasmic inheritance as a contributor to maternal effects in Welsh Mountain sheep

Cytoplasmic effects were investigated using a dataset comprising three breeding groups of Welsh Mountain sheep. The influences of cytoplasmic effects were investigated by comparing animal models with and without a random term representing cytoplasmic effects. The models were applied to the eight-week weight, scan weight (mean 152 days) and ultrasonically scanned muscle and fat depth. The animal model included the random effects of animals and the maternal additive genetic, maternal permanent environmental and maternal common environmental effects. In total there were 24 569, 10 509, 8389, 8369 records for the eight-week weight, scan weight, muscle depth and fat depth respectively. Four subsets were further analysed containing maternal lines with at least five, ten, fifteen and twenty animals/line. There was no evidence of cytoplasmic effects on eight-week weight and muscle depth. Cytoplasmic effects contributed 1–2% of phenotypic variance for scan-weight and fat depth, but the effect was generally non-significant (P > 0.05). As the number of animals per maternal line increased, the magnitude of cytoplasmic effects also increased for these traits. Direct heritability estimates for the eight-week weight, scan weight, muscle depth and fat depth using the full dataset were 0.18, 0.25, 0.24, and 0.21 respectively.     

IMMUNOGOLD LABELLING OF FIBROBLAST FOCAL ADHESION SITES VISUALISED IN FIXED MATERIAL USING SCANNING ELECTRON MICROSCOPY, AND LIVING, USING INTERNAL REFLECTION MICROSCOPY

A new immunogold labelling method for the visualisation of vinculin, an integral protein in focal adhesions of cells, is reported. Quantification of vinculin is indicative of substrate cytocompatibility (cytocompatibility is one aspect of biocompatibility; it is the cellular response to a biomaterial). For efficient labelling, most of the cell body above the cell-substrate interface was removed with detergent. The antigen blocking procedure, size of label (5 nm) and duration of silver-enhancement (6 min), for visualisation of the labelled sites on the whole cell by scanning electron microscopy (SEM), were determined. Imaging living cells with interference reflection light microscopy, followed by backscattered electron (BSE) imaging of the same fixed and immunolabelled cells confirmed the results. Collecting low voltage BSE images of embedded cells after the substrate had been removed provided 'sectional' views through the cell. This enabled visualisation of vinculin exclusively within the cell-substrate contact zone; the focal adhesions. The method could be of general use in the imaging of protein distribution at biological tissue/substrate interfaces.     

Evolution. A case of system dynamics

It is contended that the Darwinian theory of evolution is merely a special case of the obsolete Newtonian paradigm. A modern vision of reality, consistent with structuralism in biology, is presented. Some well-known neo-Darwinist explanations of the evolutionary process are quoted accompanied by structuralist interpretations of the same cases. These lead to a different 'mechanism' of evolution, based on internal factors, consistent with contemporary science. It is argued that a great number of specialists who dismiss the Darwinian theory of evolution share a common reason for rejecting it, but differ widely in guessing the motivating factor or factors of evolution.     

Proliferation and function of microbodies in the nematophagous fungus Arthrobotrys oligospora during growth on oleic acid or d-alanine as the sole carbon source

Abstract The nematophagous fungus Arthrobotrys oligospora is able to grow on oleic acid or d-alanine as the sole carbon source. During growth on oleic acid, activities of enzymes of the β-oxidation pathway, but not catalase, were induced. In the presence of d-alanine, both d-amino acid oxidase and catalase activities were enhanced. Biochemically and cytochemically, the activities of the above enzymes were assigned to microbodies. The significance of these results in relation to the function of microbodies in trophic hyphae, which are formed during nematode infection, is discussed.     

4. Progress and prospects in plant metabolism

This review considers some of the landmarks in our investigation of plant metabolism: the merging of work in vitro with that in in vivo, the use of labelled substrates, inter- and intra-cellular compartmentation. Progress in the study of the control of metabolism is reviewed from Blackman's Law of Limiting Factors via the concept of ‘Pacemaker’ reactions to determination of Control Coefficients. The tremendous opportunities afforded by the availability of mutant and transgenic plants are extolled.