Aspergillus fumigatus is exceptional among microorganisms in being both a primary and opportunistic pathogen as well as a major allergen. Its conidia production is prolific, and so human respiratory ...tract exposure is almost constant. A. fumigatus is isolated from human habitats and vegetable compost heaps. In immunocompromised individuals, the incidence of invasive infection can be as high as 50% and the mortality rate is often about 50% (ref. 2). The interaction of A. fumigatus and other airborne fungi with the immune system is increasingly linked to severe asthma and sinusitis. Although the burden of invasive disease caused by A. fumigatus is substantial, the basic biology of the organism is mostly obscure. Here we show the complete 29.4-megabase genome sequence of the clinical isolate Af293, which consists of eight chromosomes containing 9,926 predicted genes. Microarray analysis revealed temperature-dependent expression of distinct sets of genes, as well as 700 A. fumigatus genes not present or significantly diverged in the closely related sexual species Neosartorya fischeri, many of which may have roles in the pathogenicity phenotype. The Af293 genome sequence provides an unparalleled resource for the future understanding of this remarkable fungus.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Near infrared spectroscopy (NIRS) is an accurate, fast and nondestructive technique whose use in predicting forage quality has become increasingly relevant in recent decades.
-infected grass ...varieties are commonly used in areas with high pest pressure due to their better performances compared to endophyte-free varieties. The insect resistance of
-infected grasses has been associated with four main groups of endophyte secondary metabolites: ergot alkaloids, indole-diterpenes, lolines and peramine. Concentrations of these alkaloids are usually measured with high performance liquid chromatography or gas chromatography analysis, which are accurate methods but relatively expensive and laborious. In this paper, we developed a rapid method based on NIRS to detect and quantify loline alkaloids in wild accessions of
infected with the fungal endophyte
. The quantitative NIR equations obtained by modified partial least squares algorithm had coefficients of correlation of 0.90, 0.78, 0.85, 0.90 for
-acetylloline,
-acetylnorloline and
-formylloline and the sum of the three, respectively. The acquired NIR spectra were also used for developing an equation to predict in planta fungal biomass with a coefficient of correlation of 0.75. These results showed that the use of NIRS and chemometrics allows the quantification of loline alkaloids and mycelial biomass in a heterogeneous set of endophyte-infected meadow fescue samples.
The GH81 family includes proteins with endo-β-1,3-glucanase widely distributed in yeast and fungi, which are also present in plants and bacteria. We have studied the activity of the
Saccharomyces ...cerevisiae ScEng2 and the
Schizosaccharomyces pombe SpEng1 and SpEng2 proteins. All three proteins exclusively hydrolyzed linear β-1,3-glucan chains. Laminari-oligosaccharide degradation revealed that the minimum substrate length that the three endoglucanases were able to efficiently degrade was a molecule with at least 5 glucose residues, suggesting that the active site of the enzymes recognized five glucose units. Prediction of the secondary structure of ScEng2 and comparison with proteins of known structure allowed the identification of a 404-amino acid region with a structure similar to the
Clostridium thermocellum endoglucanase CelA. This fragment showed similar enzymatic characteristics to those of the complete protein, suggesting that it contains the catalytic domain of this family of proteins. Within this domain, four conserved Asp and Glu residues (D518, D588, E609, and E613) are necessary for enzymatic activity.
Schizosaccharomyces pombe cells divide by medial fission throughout contraction of an actomyosin ring and deposition of a multilayered division septum that must be cleaved to release the two daughter ...cells. Although many studies have focused on the actomoysin ring and septum assembly, little information is available concerning the mechanism of cell separation. Here we describe the characterization of eng1+, a new gene that encodes a protein with detectable endo-beta-1,3-glucanase activity and whose deletion is not lethal to the cells but does interfere in their separation. Electron microscopic observation of mutant cells indicated that this defect is mainly due to the failure of the cells to degrade the primary septum, a structure rich in beta-1,3-glucans, that separates the two sisters cells. Expression of eng1+ varies during the cell cycle, maximum expression being observed before septation, and the protein localizes to a ring-like structure that surrounds the septum region during cell separation. This suggests that it could also be involved in the cleavage of the cylinder of the cell wall that covers the division septum. The expression of eng1+ during vegetative growth is regulated by a C2H2 zinc-finger protein (encoded by the SPAC6G10.12c ORF), which shows significant sequence similarity to the Saccharomyces cerevisiae ScAce2p, especially in the zinc-finger region. Mutants lacking this transcriptional regulator (which we have named ace2+) show a severe cell separation defect, hyphal growth being observed. Thus, ace2p may regulate the expression of the eng1+ gene together with that of other genes whose products are also involved in cell separation.
Sheep production is traditional for rural communities in Mexico, based on natural grasslands and semi-stabled feeding. Quality forages are necessary to improve productivity in these systems. Weeds ...are an alternative to feed ruminants and to manage crops. Also, many plants have secondary metabolites beneficial for livestock. The objective was to assess the nutritive value in vitro and the antioxidant activity of three weeds (
Tithonia tubiformis
,
Cosmos bipinnatus
, and
Tagetes lucida
) and four treatments (T0 = control diet, T1 = diet + 5%
T. tubiformis
, T2 = diet + 5%
C. bipinnatus
, and T3 = diet + 5%
T. lucida
). Nutritive value was determined from chemical composition by standard methods and mineral contents by inductively coupled plasma analyses. Secondary compounds, total phenols (TP), total tannins (TT), condensed tannins (CT), and phenolic compounds, were determined by high-performance liquid chromatography, and total antioxidant activity was determined by measuring the oxygen radical absorbance capacity. Rumen fermentation kinetics and in vitro digestibility of dry matter (IVDMD), organic matter (IVOMD), and neutral detergent fibre (IVNDFD) were determined per species and treatment by in vitro gas production.
T. tubiformis
had the highest CP and TP contents (
P
< 0.05), and
C. bipinnatus
had the highest fibre and CT contents (
P
< 0.05). Inclusion of
T. lucida
in the diet resulted in an 18% increase in TP content and a 30% increase in antioxidant activity in comparison to the control diet. No significant differences (
P
> 0.05) were found in rumen kinetics parameters, IVDMD, IVOMD, IVNDFD, or metabolizable energy, indicating that the tested weeds can be used as additives to increase antioxidant activity in sheep diets without negative effects.
Schizosaccharomyces pombe cells divide by medial fission through contraction of an actomyosin ring and deposition of a multilayered division septum that must be cleaved to release the two daughter ...cells. Here we describe the identification of seven genes (adg1(+), adg2(+), adg3(+), cfh4(+), agn1(+), eng1(+), and mid2(+)) whose expression is induced by the transcription factor Ace2p. The expression of all of these genes varied during the cell cycle, maximum transcription being observed during septation. At least three of these proteins (Eng1p, Agn1p, and Cfh4p) localize to a ring-like structure that surrounds the septum region during cell separation. Deletion of the previously uncharacterized genes was not lethal to the cells, but produced defects or delays in cell separation to different extents. Electron microscopic observation of mutant cells indicated that the most severe defect is found in eng1Delta agn1Delta cells, lacking the Eng1p endo-beta-1,3-glucanase and the Agn1p endo-alpha-glucanase. The phenotype of this mutant closely resembled that of ace2Delta mutants, forming branched chains of cells. This suggests that these two proteins are the main activities required for cell separation to be completed.
The division cycle of unicellular yeasts is completed with the activation of a cell separation program that results in the dissolution of the septum assembled during cytokinesis between the 2 ...daughter cells, allowing them to become independent entities. Expression of the eng1(+) and agn1(+) genes, encoding the hydrolytic enzymes responsible for septum degradation, is activated at the end of each cell cycle by the transcription factor Ace2. Periodic ace2(+) expression is regulated by the transcriptional complex PBF (PCB Binding Factor), composed of the forkhead-like proteins Sep1 and Fkh2 and the MADS box-like protein Mbx1. In this report, we show that Ace2-dependent genes contain several combinations of motifs for Ace2 and PBF binding in their promoters. Thus, Ace2, Fkh2 and Sep1 were found to bind in vivo to the eng1(+) promoter. Ace2 binding was coincident with maximum level of eng1(+) expression, whereas Fkh2 binding was maximal when mRNA levels were low, supporting the notion that they play opposing roles. In addition, we found that the expression of eng1(+) and agn1(+) was differentially affected by mutations in PBF components. Interestingly, agn1(+) was a major target of Mbx1, since its ectopic expression resulted in the suppression of Mbx1 deletion phenotypes. Our results reveal a complex regulation system through which the transcription factors Ace2, Fkh2, Sep1 and Mbx1 in combination control the expression of the genes involved in separation at the end of the cell division cycle.
The Candida albicans CaENG1 gene encoding an endo-1,3-beta-glucanase was cloned by screening a genomic library with a DNA probe obtained by polymerase chain reaction using synthetic oligonucleotides ...designed according to conserved regions found between two Saccharomyces cerevisiae endo-1,3-beta-glucanases (Eng1p and Eng2p). The gene contains a 3435-bp open reading frame (ORF), capable of encoding a protein of 1145 amino acids (124,157 Da), that contains no introns. Comparison of the ScEng1p sequence with partial C. albicans genomic sequences revealed the presence of a second protein with sequence similarity (the product of the Ca20C1.22c ORF, which was named CaENG2). Disruption of the CaENG1 gene in C. albicans had no dramatic effects on the growth rate of the strains, but it resulted in the formation of chains of cells, suggesting that the protein is involved in cell separation. Expression of CaENG1 in S. cerevisiae cells afforded a 12-fold increase in the 1,3-beta-glucanase activity detected in culture supernatants, showing that the protein has similar enzymatic activity to that of the S. cerevisiae Eng1p. In addition, when the C. albicans protein was expressed under its native promoter in S. cerevisiae eng1 mutant cells, it was able to complement the separation defect of this mutant, indicating that these two proteins are true functional homologues.
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