POLYPLOIDY IN THE BASIDIOMYCETE CYATHUS STERCOREUS

Chromosome analysis of the basidiomycete Cyathus stercoreus (Nidulariaceae) reveals that certain chromosomes of the haploid complement structurally resemble one another. These like chromosomes exhibit with high frequency a tendency to form quadrivalents or to show secondary association at diplotene and diakinesis of meiosis, suggesting some degree of homology. This indicates that C. stercoreus is a tetraploid species. It is suggested that the polyploidy of the present species may have resulted from allotetraploidy involving species which may have been evolved from a single ancestor.     

Decolorization of triphenylmethane dyes by the bird's nest fungus Cyathus bulleri

Decolorization of three triphenylmethane dyes by three bird's nest fungi—Cyathus bulleri, C. stercoreus, and C. striatus—was studied. Cyathus bulleri was found to be the most efficient in decolorization as demonstrated by the disappearance of the dyes from cultures, monitored by decreases in absorbance. Growth of the Cyathus spp. was not affected by the presence of dyes in the cultures. Decolorization of dyes was also observed with extracellular culture filtrates, indicating exocellular activity. Laccase activity, tested in replicate cultures, was found to be maximum during the decolorization period. Nitrogen in the medium had no effect on decolorization.     

Treatment of rice straw with selected Cyathus stercoreus strains to improve enzymatic saccharification

Seventeen Cyathus stercoreus isolates were tested for their ability to treat rice straw for improved enzymatic saccharification. These isolates showed a negative correlation between cellulase and xylanase activity and enzymatic saccharification yields. Incubation of rice straw pretreated at 60 °C for 15 min with strain C. stercoreus TY-2 for 25 days resulted in an enzymatic saccharification yield of 57% as compared to a yield of 11% for the same straw in the absence of the fungus. These findings highlight the potential of this isolate for biological pretreatment of rice straw under conditions of low energy input.     

Decomposition of Lignocellulose by Cyathus stercoreus (Schw.) de Toni NRRL 6473, a “White Rot” Fungus from Cattle Dung

Cyathus stercoreus (Schw.) de Toni NRRL 6473, isolated from aged and fragmented cattle dung collected from a Michigan pasture, effected substantial losses in lignin (45%) from wheat straw during a 62-day fermentation (25°C). The basidiomycete also improved wheat straw digestibility by freeing α-cellulose for enzymatic hydrolysis to glucose (230 mg of glucose per 1,000 mg of fermented residue). The rationale for selecting C. stercoreus in attempting to biologically modify the lignin and cellulose components in wheat straw or other gramineous agricultural residues was based on the expectation that this organism is ecologically specialized to enzymatically attack the substructures of native lignins in grasses.     

Production of ligninolytic enzymes and synthetic lignin mineralization by the bird's nest fungus Cyathus stercoreus

Production of ligninolytic enzymes and degradation of ¹⁴C-ring labeled synthetic lignin by the white-rot fungus Cyathus stercoreus ATCC 36910 were determined under a variety of conditions. The highest mineralization rate for ¹⁴C dehydrogenative polymerizates (DHP; 38% ¹⁴CO₂ after 30 days) occurred with 1 mM ammonium tartrate as nitrogen source and 1% glucose as additional carbon source, but levels of extracellular laccase and manganese peroxidase (MnP) were low. In contrast, 10 mM ammonium tartrate with 1% glucose gave low mineralization rates (10% ¹⁴CO₂ after 30 days) but higher levels of laccase and manganese peroxidase. Lignin peroxidase was not produced by C. stercoreus under any of the studied conditions. Mn(II) at 11 ppm gave a higher rate of ¹⁴C DHP mineralization than 0.3 or 40 ppm, but the highest manganese peroxidase level was obtained with Mn(II) at 40 ppm. Cultivation in aerated static flasks gave rise to higher levels of both laccase and manganese peroxidase compared to the levels in shake cultures. 3,4-Dimethoxycinnamic acid at 500 μM concentration was the most effective inducer of laccase of those tested. The purified laccase was a monomeric glycoprotein having an apparent molecular mass of 70 kDa, as determined by calibrated gel filtration chromatography. The pH optimum and isoelectric point of the purified laccase were 4.8 and 3.5, respectively. The N-terminal amino acid sequence of C. stercoreus laccase showed close homology to the N-terminal sequences determined from other basidiomycete laccases. Information on C. stercoreus, whose habitat and physiological requirements for lignin degradation differ from many other white-rot fungi, expands the possibilities for industrial application of biological systems for lignin degradation and removal in biopulping and biobleaching processes. Received: 29 January 1999 / Received revision: 5 July 1999 / Accepted: 9 July 1999     

Production and characterization of a xylanase from Cyathus stercoreus

Cyathus stercoreus grown on wheat straw had a higher xylanase activity than when it was grown on rice husk or extracted hemicellulose. Inclusion of casein hydrolysate, Tween 80 and Mn²⁺ (at 0.02%, 0.2% and 0.075%, respectively) increased the production of extracellular xylanase. Optimal yield of xylanase (0.73 U/ml) was at pH 5.6 after 9 to 12 days at 30°C. The xylanase was stable at pH 4.5 to 7.5 for 2h but above 50°C its stability fell sharply.The authors are with the Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021, India;     

Cyathuscavins A, B, and C, new free radical scavengers with DNA protection activity from the Basidiomycete Cyathus stercoreus

Three new polyketides, cyathuscavins A (1), B (2), and C (3) were isolated from the mycelium culture of Cyathus stercoreus. The structures of the compounds were elucidated on the basis of NMR and mass spectroscopic data. Antioxidant activities of the compounds were evaluated by the scavenging ability against ABTS⁺, DPPH, and superoxide anion radicals. Cyathuscavins A–C showed significant antioxidant activity comparable to those of reference antioxidants, BHA and Trolox. Cyathuscavins A–C protected supercoiled plasmid DNA from Fe²⁺/H₂O₂-induced breakage.     

THE ROLE OF LIGHT IN FRUCTIFICATION OF THE BASIDIOMYCETE CYATHUS STERCOREUS

Fructification in cultures of Cyathus stercoreus (Schw.) de Toni is a process in which photochemical reactions are involved. The amount of light energy required for fruiting to take place is a constant. This photoinductive constant is approximately 17200 foot-candle-hours considering optimum temperature (25 C) and light-saturation effect with reference to light intensity (240 ft-c). It is hypothesized that photoinduction becomes operative when a hypothetical “photoreceptive precursor” develops in the mycelium. The development of such a precursor is believed to occur when conditions unfavorable for good vegetative growth (e.g. shortage of food supply) develop in the culture. Internal metabolic pathways then shift to favor the production of the photoreceptive precursor. A linear function is derived which characterizes the biological photoinduction of fruit-body formation.     

The evidence for a meiotic process in the euglenineae

Summary Cells of Hyalophacus ocellatus are described which contain either a nuclear figure consisting of a double complement of highly condensed chromosomes arranged in pairs in the anterior half of the cell, or a huge posteriorly-placed nucleus consisting of long granular chromosomes which also show signs of pairing. These nuclear figures are quite unlike interphase nuclei or stages in mitosis and are thought to be stages in euglenoid meiosis.No evidence has been obtained for a sexual fusion of gametes or cells. Previous accounts of sexuality and autogamy in the Euglenineae are historically reviewed and critically discussed relative to the present observations.This paper is dedicated to Professor Dr. E. G. Pringsheim on the occasion of his 80th birthday, with gratitude both for his untiring advice on my research and for his friendship.     

Biodelignification of lignocellulose substrates: An intrinsic and sustainable pretreatment strategy for clean energy production

Lignocellulosic biomass (LB) is a promising sugar feedstock for biofuels and other high-value chemical commodities. The recalcitrance of LB, however, impedes carbohydrate accessibility and its conversion into commercially significant products. Two important factors for the overall economization of biofuel production is LB pretreatment to liberate fermentable sugars followed by conversion into ethanol. Sustainable biofuel production must overcome issues such as minimizing water and energy usage, reducing chemical usage and process intensification. Amongst available pretreatment methods, microorganism-mediated pretreatments are the safest, green, and sustainable. Native biodelignifying agents such as Phanerochaete chrysosporium, Pycnoporous cinnabarinus, Ceriporiopsis subvermispora and Cyathus stercoreus can remove lignin, making the remaining substrates amenable for saccharification. The development of a robust, integrated bioprocessing (IBP) approach for economic ethanol production would incorporate all essential steps including pretreatment, cellulase production, enzyme hydrolysis and fermentation of the released sugars into ethanol. IBP represents an inexpensive, environmentally friendly, low energy and low capital approach for second-generation ethanol production. This paper reviews the advancements in microbial-assisted pretreatment for the delignification of lignocellulosic substrates, system metabolic engineering for biorefineries and highlights the possibilities of process integration for sustainable and economic ethanol production.     

Early chromosome condensation without cell fusion. I. Preliminary results with allogeneic and xenogeneic cells.

Early chromatin condensation in interphase cells (G1) of human peripheral blood lymphocytes has been induced without virus or cell fusion by exposure to allogeneic or xenogeneic mitotic cells. The event, although similar in some ways to the phenomenon described as "premature chromosome condensation," "chromosome pulverization," and "prophasing," differs in that it does not require the presence of viruses and cell fusion before mitosis proceeds in the G1 cell. Early chromatin condensation in interphase cells induced by mitotic cells only, consists of chromatids in the early or late G1 phase of the cell cycle that are not pulverized or fragmented at mitosis. Some of the chromosomes are twice as long as the metaphase chromosomes and exhibit natural bands. Almost twice as many of these bands are produced as by trypsin treatment of metaphase chromosomes. The nuclear membrane is intact and nucleoli are present, to which some chromosomes are attached. The DNA content of the precocious chromosomes in G1 is half the amount of the metaphase complement.     

ENDOMITOSIS IN TAPETAL CELLS OF EREMURUS (LILIACEAE)

True endomitosis in the anther tapetum of the liliaceous plant Eremurus is described. The nuclear membrane does not disappear, but during metaphase the chromosomes are condensed, often considerably more than in normal mitosis. When the pollen mother cells (PMCs) go through the last premeiotic mitosis, the tapetal cells have one diploid nucleus which divides while the cell remains undivided. The two diploid nuclei may undergo an endomitosis and the resulting tetraploid nuclei a second endomitosis. An alternative pathway is an ordinary mitosis—again without cell division—instead of one of the endomitotic cycles. The cytological picture in the tapetum is further complicated by restitution in anaphase and fusion of metaphase and anaphase groups during mitosis, processes which could give rise to cells with one, two, or three nuclei, instead of the expected two or four. No sign of the so-called “inhibited” mitosis is seen in these tapetal cells. When the PMCs are in leptotene-zygotene, very few tapetal nuclei are in endomitosis. When the PMCs have reached diplotene, almost 100% of cells which are not in interphase show an endomitotic stage.     

Sulla Terminologia dei Processi Mitotici

Summary

The Author has proposed to establish a general plan for the best known modality of the mitosis discovered in these last years in the higher organism animals and vegetables. Two facts are taken in consideration: the distribution of the chromosomes in the anaphase and the chromosome structure. When the distribution of the chromosomes is unever, the mitosis is called with the phrase “mitosis with irregular distribution” (case of the distribution of the chromosomes non regular between the two poles), or “restitutional mitosis” (case of the forming of the restitution nucleus in metaphase or in the anaphase), or “endorestitutional mitosis” (case of the return of the resting stage before the end of the prophase).

A special case is given when is present the accessory phenomenon of the somatic pairing, in which case the mitosis is called precisely “mitosis with somatic pairing”. The Author regards to the mechanism of the mitosis, observes that the determination of the structure gone beyond the chromatid has not value because the anaphase distributes as a rule whole chromatids. From this point of view the types of chromosomes experimentally observed in an undoubted manner are exactly: monochromosomes, diplochromosomes, polychromosomes, univalents, bivalents, polivalents, diplounivalents and diplobivalents. These two last types of the chromosomes are observed during the first mitosis of the spore, in cases in which the meiosis respectively fails in the interkinesis or before the heterotypic anaphase. The term diplounivalent is originated by the author to distinguish this type of chromosome (that though present in the mitosis is however of meiotic origin) from the other type (the diplochromosome) that has same structure but not of meiotic origin. (The diplochromosome is owing to a supernumerary reproduction of the usual mitotic chromosome).

It is also describes, as far as it can be said accuracy, the course of the different types in metaphase and in anaphase. Keeping thus in mind the chromosome structure (the chromatid is considered as a unity) the mitosis is subdivided in the following types: 1° Mitosis with monochromosomes; 2° Mitosis with diplochromosomes; 3° Mitosis with polychromosomes; 4° Mitosis with diplounivalents; 5° Mitosis with diplobivalents.

The terms proposed considering the chromosome distribution or the chromosome structure can be combinable so that the mitosis with monocromosomes (etc). can be called “restitutional mitosis with monochromosomes” (as for instance in the case of the action of the colchicine), or endorestitutional mitosis with monochromosomes (as for istance in the case of the tapetal cells of Spinacia). Not adding either the term restitutional or endorestitutional, it is understood that the course of the mitosis is regular right up to the end.

In the course of his research the Autor shows a personal explanation for the “later divisions ” in Culex (Berger 1938, Grell 1946) and points out the necessarity of new researches on the mitotic, supramitotic, etc. chromosomes type of Trillium (Matssuura e Haga 1940).     

Molecular differentiation of sex chromosomes probed by comparative genomic hybridization

Comparative genomic hybridization (CGH) was used to identify and probe sex chromosomes in several XY and WZ systems. Chromosomes were hybridized simultaneously with FluorX-labelled DNA of females and Cy3-labelled DNA of males in the presence of an excess of Cot-1 DNA or unlabelled DNA of the homogametic sex. CGH visualized the molecular differentiation of the X and Y in the house mouse, Mus musculus, and in Drosophila melanogaster: while autosomes were stained equally by both probes, the X and Y chromosomes were stained preferentially by the female-derived or the male-derived probe, respectively. There was no differential staining of the X and Y chromosomes in the fly Megaselia scalaris, indicating an early stage of sex chromosome differentiation in this species. In the human and the house mouse, labelled DNA of males in the presence of unlabelled DNA of females was sufficient to highlight Y chromosomes in mitosis and interphase. In WZ sex chromosome systems, the silkworm Bombyx mori, the flour moth Ephestia kuehniella, and the wax moth Galleria mellonella, the W chromosomes were identified by CGH in mitosis and meiosis. They were conspicuously stained by both female- and male-derived probes, unlike the Z chromosomes, which were preferentially stained by the male-derived probe in E. kuehniella only but were otherwise inconspicuous. The ratio of female:male staining and the pattern of staining along the W chromosomes was species specific. CGH shows that W chromosomes in these species are molecularly well differentiated from the Z chromosomes. The conspicuous binding of the male-derived probe to the W chromosomes is presumably due to an accumulation of common interspersed repetitive sequences. Received: 6 January 1999; in revised form: 28 January 1999 / Accepted: 11 February 1999     

Cytogenetic studies of cultivatedCrocus sativus (Iridaceae)

Meiosis and mitosis are described in cultivatedCrocus sativus of Iran. This indicates that this species is an autotriploid and sterile. Karyotype analysis, rare inversions, laggard chromosomes and distribution of chromosomes in the first anaphase are described, and the reasons for its sterility are given.     

Mitosis in flat PTK2-human hybrid cells

The fusion of G0 human fibroblasts with PTK₂ (Potorous tridactylis) cells resulted in the production of hybrid heterokaryotic cells which remained flat in cell division. These cells permitted studies of mitosis in living hybrid cells without the need for fixation and staining. The breakdown of nuclear envelopes during prophase in a hybrid heterokaryotic cell correlated with the onset of premature chromosome condensation (PCC) in other nuclei in the same cell. Nuclear morphology and autoradiography demonstrated that the nuclei exhibiting PCC were from the human parent cells. Observation of multinucleated PTK₂-human hybrids in the later stages of mitosis showed that these cells normally produced three daughters instead of the usual two. Electron microscopic examination of dividing hybrid cells showed that the number of daughter cells was not related to the number of centrioles. Hybrid cells normally were found to contain many centriolar duplexes although not all of these structures were associated with active poles in mitosis. Cells with as many as six centriolar duplexes were found in mitosis. The configuration of the chromosomes in metaphase was found to be a more accurate indication of the number of daughters produced by a single division than the number of centrioles. Chromosome elimination in hybrid cells could also be visualized in PTK₂-human hybrids. Lagging chromosomes were commonly observed during mitosis and were often trapped in the constricting midbody.     

Ultrastructure of holokinetic mitotic chromosomes and interphase nuclei of Tetranychus urticae Koch (Acari,Tetranychidae) in relation to loss and missegregation of induced fragments

The association of microtubules with mitotic holokinetic chromosomes of Tetranychus urticae Koch was investigated in serial ultrathin sections. Reconstructions from 14 series showed that 60–100 microtubules were associated with the entire poleward surfaces of the chromosomes. In the telophase of early developmental stages the chromosomes were decondenseed into separate micronuclei, containing at least one nucleolus. From these morphologic data, the fate of induced chromosome fragments, described in earlier papers, is surmised to depend on events in interphase as well as in mitosis.     

The effect of B chromosomes on meiotic and pre-meiotic spindles and chromosome pairing in Triticum/Aegilops hybrids

Diploid populations of Aegilops mutica and Aegilops speltoides containing B chromosomes have been used as male parents in crosses with aneuploid genotypes of Triticum aestivum to investigate the effect of B chromosomes on meiotic homologous and homoeologous chromosome pairing. F₁ hybrids of T. aestivum/Ae. mutica and T. aestivum/Ae. speltoides segregated into four classes with regard to the degree of meiotic chromosome pairing, irrespective of the presence of B chromosomes. The B chromosomes do not introduce factors altering the level of pairing other than that due to the natural allelic and gene variation occurring in the diploids. Similarly no reduction in pairing of homologous chromosomes was observed in genotypes in which pairs of homologues co-existed with B chromosomes. However, a significant drop in chiasma frequency was observed in F₁ hybrids of T. aestivum × Ae. mutica with B chromosomes and T. aestivum × Ae. mutica nullisomic for wheat chromosome 5D with B chromosomes, in temperature regimes of 12° C. No asynapsis occurred in similar hybrids in the absence of Mutica B chromosomes at low temperatures. The low-temperature sensitive phase lies early in the pre-meiotic interphase. In this instance the Mutica B chromosomes are interacting with specific gene loci of the A chromosomes. Synaptic pairing has been observed between A and B chromosomes in Ae. mutica. A high frequency of pollen mother cells with twice the number of chromosomes was observed in hybrids in the presence of Mutica B chromosomes due to failure of spindle formation at the last pre-meiotic mitosis. Meiotic spindle irregularities occurred in hybrids containing Speltoides B chromosomes. Hybrids of Ae. speltoides + B's X Ae. mutica + B's displayed the mitotic and meiotic spindle abnormalities introduced by the presence of the B chromosomes of each parent.     

The effects of X-rays on the chromosomes of locust embryos

The structure and frequency of chromatid interchange types in C-metaphase cells of embryos of Schistocerca gregaria are described at the first mitosis following irradiation at the G ₂ stage of interphase. The relationship between the different interchange types and the organisation of the interphase nucleus is discussed. It is concluded that most chromatid interchanges are induced between polarised chromosomes though the occurrence of loops and to a lesser extent of terminal overlapping may subsequently modify the appearance of these aberrations at metaphase.     

Degradation of Lignin by Cyathus Species

The ability of 12 Cyathus species to degrade ¹⁴C-labeled lignin in kenaf was studied. The sum of ¹⁴C released into solution plus ¹⁴C released into the gas phase over a 32-day fermentation period was used to determine average daily rates of lignin biodegradation. Cyathus pallidus. C. africanus, and C. berkeleyanus delignified kenaf most rapidly. C. canna showed the greatest preference for lignin degradation over other plant components, and its rate of lignin degradation was only slightly lower than the three most active species. The apparent ability of fungi to metabolize low-molecular-weight lignin breakdown products correlated well with their overall delignification rates. C. stercoreus metabolized degradation products of lignin from wheat straw better than those from kenaf lignin, based on the amount of low-molecular-weight products left in solution.