Genome reorganization during cellular senescence

It was previously suggested that aging of dividing cells depends on the reorganization of the cell genome during the division cycle and is determined by chance, intrinsic properties of the genome and environmental factors. A considerable amount of evidence has accumulated supporting the hypothesis. This is reviewed in terms of the reorganization taking place at the different orders of DNA structure.     

Development and evaluation of polyclonal antibodies for detection of Pythium aphanidermatum and Fusarium oxysporum in ginger

Polyclonal antibodies against Pythium aphanidermatum and Fusarium oxysporum proteins were developed for the detection of rhizome rot in ginger using serological assays. Under optimal experimental conditions, the detection limit of P. aphanidermatum by indirect ELISA was 10?µg/ml with a linear working range from 5 to 100?µg/ml (R²?=?0.994). In case of F. oxysporum, the linear working range was 5–100?µg/ml (R²?=?0.991) and the limit of detection was 25?µg/ml. The developed antibodies showed the highest titer in ELISA at 1:2000 dilutions. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis identified proteins ranging from molecular weights 15–97?kDa and 14–116?kDa of P. aphanidermatum and F. oxysporum isolates, respectively. In Western blot analysis, the developed antisera gave positive reactions against the isolated antigens of the fungi. The antibodies revealed immune-reactive bands of molecular weights 59 and 65?kDa in P. aphanidermatum and 44 and 75?kDa in F. oxysporum. The results suggest that the developed antibodies could be successfully applied for the specific immunodetection of P. aphanidermatum and F. oxysporum at an early stage of rhizome rot disease.     

Urinary tract infection due to Fusarium oxysporum in an immunocompetent patient with chronic kidney disease

Infections due to Fusarium species are collectively referred to as fusariosis. Fusarium oxysporum has been reported to cause keratitis, onychomycosis, skin infections, catheter associated fungemia and has not been described as a cause of urinary tract infection. Here, we present the first case of fusariosis with urinary tract involvement in a 67 year old male, with chronic kidney disease and type 2 diabetes mellitus. This case illustrates the ever increasing spectrum of rare but offending pathogenic fungi. Early diagnosis of infection with a specific pathogen may lead to changes in antifungal therapy and may be critical for an improved outcome.     

The mitochondrial DNA of the yeast Hansenula petersonii: genome organization and mosaic genes

Summary The mitochondrial genomes of yeasts are circular DNA molecules that vary greatly in size in different species. The mitochondrial DNA of the yeast H. petersonii is about 42 kbp in length, about one half the size of the corresponding genome in S. cerevisiae. Sequences homologous to protein-encoding genes from S. cerevisiae have been identified and localized on this genome by hybridization with DNA from petite mutants. The comparison between the mitochondrial genomes of H. petersonii and S. cerevisiae showed differences in the overall genome organization, but both include genes with mosaic organization. In fact, sequences homologous to the first intron of the S. cerevisiae cob short gene are found in (or adjacent to) the cob and cox1 genes present in the genome of H. petersonii. Moreover, an intron homologous to that present in the 21S rRNA gene of S. cerevisiae seems to have been conserved in the large ribosomal RNA gene of H. petersonii, in a similar position.     

Complete nucleotide sequences and genome organization of four chimpanzee adenoviruses

The complete nucleotide sequences for four adenoviruses-Simian Adenoviruses 21, 22, 23, and 24, originally isolated from chimpanzees, were determined. The genome organization of the chimpanzee adenoviruses was found to be similar to that of other adenoviruses. The viral gene products of the adenoviruses Simian Adenoviruses 22, 23, and 24 are very closely related to those of the (previously sequenced) chimpanzee adenovirus Simian Adenovirus 25. Simian Adenovirus 21 is most similar to human subgroup B adenoviruses HAdV-3, HAdV-7, and HAdV-35. Analysis of the capsid proteins hexon and fiber of the chimpanzee adenoviruses also supports the placement of Simian Adenovirus 21 in subgroup B and Simian Adenoviruses 22, 23, and 24 in subgroup E.     

Genetic transformation of the fungal plant wilt pathogen,Fusarium oxysporum

Summary A system for transformation of the fungal plant pathogen Fusarium oxysporum has been developed. The system employs plasmids which contain a bacterial hygromycin B phosphotransferase gene (hph) linked to Aspergillus regulatory sequences and which confer hygromycin B resistance in Fusarium. Transformation resulted from integration of the vectors into heterologous regions of the Fusarium genome and occurred at a frequency of approximately one transformant per µg DNA. No evidence was found for autonomous replication of the vector in the fungus. The transformed, drug resistant phenotype was mitotically stable with or without selection. However, modification of integrated DNA could occur during vegetative growth.     

The non-coding region of BK subtype II viruses

Four BK virus (BKV) subtypes are distinguishable by serological and molecular methods. The type I followed by type IV represents the most common subtype. Subtypes II and III occur rarely. The complete sequence of a German subtype II isolate was determined. The lack of data on the structure of the non-coding region (NCR) of subtype II and III viruses prompted us to study this part of the genome in more detail. Sequence comparisons revealed that the archetypal configuration of subtype I strain WW seems to be predominant among BKV subtypes.     

Influence of biological parameters and gene transfer technique on transformation of Fusarium oxysporum

Summary An improved method for PEG-mediated transformation of the fungal pathogen Fusarium oxysporum was developed which led to at least a 10-fold increase in transformation frequency. This improvement was gained through the analysis of biological factors, viz., protoplast origin, plasmid modifications and protoplast/plasmid ratio. Elecroporation, a recently developed method for introducing DNA into many cell types, was successfully applied. It gave similar transformation efficiencies to those obtained with the chemical method, and thus appeared a valuable alternative. Qualitative features such as integration events were also analysed. Molecular analysis of transformants revealed that a single copy of plasmid DNA was preferentially integrated by electroporation. The respective advantages of the two DNA transfer methods are discussed.Abbreviations (CM) complete medium (Daboussi 1980) - (MM) minimal medium (Daboussi 1980) - (MS) 10 mM MOPS, pH 6.3, 1 M sorbitol - (MSC) MS with 10 mM CaCl₂ - (HS) 5 mM HEPES, pH 6.3, 20% sucrose - (PEG) polyethylene glycol - (FD) microfarad     

Structural organization of the genome of the zygomycete Absidia glauca: evidence for high repetitive DNA content

Summary Total cell DNA of Absidia glauca has a GC-content of 44.6% ± 0.5% as determined from optical melting profiles which is in good accordance with values from equilibrium centrifugation in bisbenzimide containing CsCl gradients (46.2% = 1.1%), whereas mitochondrial DNA has a GC-content of only 30%. The genome size of Absidia glauca is approximately 36,000 kb, 8.6 times that of Escherichia coli. Three kinetically different fractions could be identified in reassociation experiments: a foldback-DNA fraction, comprising approximately 10% of the total DNA, repetitive DNA (25%) and single copy DNA (65%). This relatively high amount of repetitive DNA could partly be ascribed to ribosomal DNA (13%) and a new interspersed repetitive element (rAg1) which has been cloned in pBR325.     

A family of repeated DNA in the genome of the oomycete plant pathogen Phytophthora cryptogea

We have identified a family of repetitive sequences, called PCISs (Phytophthora Cryptogea Insertion Sequences), in the genome of Phytophthora cryptogea. They vary greatly in size (in a 100–1200 bp range) and appear to represent 3′ terminal fragments of a larger element. Two subfamilies were characterised on the basis of nucleotide sequences. PCISs exhibit insertion polymorphism, as well as a very low sequence divergence. Most copies are flanked by terminal direct repeats, suggesting that their spreading involves insertion events rather than rearrangements. PCISs are found in very few copies in Phytophthora cinnamomi. The spreading of these sequences within the genus Phytophthora is discussed. Received: 15 October 1998 / 7 April 1999     

亚洲戊型肝炎病毒结构蛋白的变异

目的了解戊型肝炎病毒的变异。方法用双脱氧法对亚洲主要戊型肝炎流行国家的戊型肝炎病毒结构基因区段进行了分析，并根据ｃＤＮＡ序列确定了其氨基酸的序列。结果证明亚洲国家包括印度、缅甸、中国、巴基斯坦、吉尔吉斯坦流行的戊型肝炎病毒在基因水平和氨基酸水平上均有变化，核苷酸变化幅度在５％以内。氨基酸在测定的区域内未发现变异，与美洲发现的墨西哥株相比，亚洲株拟来自同一个祖先，基因和氨基酸水平的变化仅属基因漂移的范围。结论以亚洲戊型肝炎病毒基因为基础的疫苗将有广泛的保护作用     

Genome sequence and organization of a nucleopolyhedrovirus isolated from the smaller tea tortrix, Adoxophyes honmai

Adoxophyes honmai nucleopolyhedrovirus (AdhoNPV) has a distinctive pathology in A. honmai larvae, killing the host more slowly than other NPVs. To further understand the pathology of AdhoNPV, its genome was completely sequenced and compared with those of other baculoviruses. The AdhoNPV genome is 113,220 bp, with a G + C content of 35.6%. It contains 125 putative open reading frames (ORFs), of which 8 are unique to AdhoNPV, and 4 homologous regions. The other 117 ORFs display similarity to previously characterized baculovirus genes involved in early and late gene expression, DNA replication, and structural and auxiliary functions. The phylogenetic position of AdhoNPV, in relation to 15 other baculoviruses whose genomes have been completely sequenced, was assessed by three different analyses: gene sequence, gene order, and gene content. Although gene content analysis failed to support the group II NPVs, phylogenetic trees based on gene sequence and gene order showed AdhoNPV to be closely related to the group II NPVs.     

Contribution of cell wall degrading enzymes to pathogenesis of Fusarium graminearum: a review

Plant‐pathogenic fungi produce an array of extracellular hydrolytic enzymes that enable them to penetrate and infect the host tissue; these enzymes are collectively called cell wall‐degrading enzymes (CWDE). They may contribute to pathogenesis by degrading wax, cuticle and cell walls, thus aiding tissue invasion and pathogen dissemination. Furthermore, they can act as elicitors of host defense reaction. Fusarium head blight (FHB) is a disease caused principally by Fusarium graminearum on crops, occurring all over the world. Important economic losses on wheat‐growing areas have been registered by altering quality parameters of grains. Significant progress has been made in understanding the infection process from F. graminearum on wheat, based on genomic technologies. The virulence degree of this phytopathogen on crops could arise from differences in the production of extracellular enzymes, factors controlling the establishment of infection. Fusarium graminearum isolates from different geographical areas have been examined, and a combination of morphological and molecular data allowed the division of fungi in diverse groups, which have been related to the variation in pathogenicity. In most studied cases there is a correlation between the presence of pectic enzymes, disease symptom and virulence, being also their production decisive in the infection process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Identification of new galactose oxidase genes in Fusarium spp.

Galactose oxidase (GO) converts galactose to an aldehyde and has several biotechnological applications, including cancer diagnosis. It is mainly produced by Fusarium austroamericanum but is also produced by Fusarium acuminatum and by isolates of the Fusarium graminearum and Gibberella fujikuroi complexes. The F. austroamericanum GO gaoA gene has been cloned, but the GO genes from other secreting species have not been characterized. Problems associated with the F. austroamericanum GO such as high pI and low catalytic efficiency and thermostability, and the difficult purification process makes the search for homologous genes attractive. In this work, the GO genes from Fusarium verticillioides and Fusarium subglutinans, two species of the G. fujikuroi complex, were cloned, sequenced, and analyzed. New GO genes were found in databases and were used to construct a phylogenetic tree, which revealed the existence of three orthologous lineages of GO genes in Fusarium spp. In addition, RT‐PCR analyses revealed that the new GO cloned gene may be endogenously expressed in F. subglutinans but not in F. verticillioides, in the used culture conditions. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ultrastructure of the dorsal claustrum in cat. II. Synaptic organization

The claustrum is a bilateral subcortical nucleus situated between the insular cortex and the striatum in the brain of all mammals. It consists of two embryologically distinct subdivisions - dorsal and ventral claustrum. The claustrum has high connectivity with various areas of the cortex, subcortical and allocortical structures. It has long been suggested that the various claustral connections have different types of synaptic contacts at the claustral neurons. However, to the best of our knowledge, the literature data on the ultrastructural organization of the different types of synaptic contacts in the dorsal claustrum are very few. Therefore, the aim of our study was to observe and describe the synaptic organization of the dorsal claustrum in the cat. We used a total of 10 adult male cats and conducted an ultrastructural study under a transmission electron microscope as per established protocol. We described a multitude of dendritic spines, which were subdivided into two types - with and without foot processes. Based on the size and shape of the terminal boutons, the quantity and distribution of vesicles and the characteristic features of the active synaptic zone, we described six types of synaptic boutons, most of which formed asymmetrical synaptic contacts. Furthermore, we reported the presence of axo-dendritic, axo-somatic, dendro-dendritic and axo-axonal synapses. The former two likely represent the morphological substrate of the corticoclaustral pathway, while the remaining two types have the ultrastructural features of inhibitory synapses, likely forming a local inhibitory circuit in the claustrum. In conclusion, the present study shares new information about the neuropil of the claustrum and proposes a systematic classification of the types of synaptic boutons and contacts observed in the dorsal claustrum of the cat, thus supporting its key and complex role as a structure integrating various information within the brain.     

Involvement of Fusarium spp. in fungal keratitis

Members of the filamentous fungal genus Fusarium are among the agents most frequently causing keratomycosis in humans. Fusarium keratitis is most common among agricultural workers in geographical regions with hot, humid, tropical or semi-tropical climates, but can occur more rarely in countries with temperate climates, such as Hungary. Keratitis is usually treated with a topical antifungal agent, sometimes in combination with sub-conjunctival injections and/or antimycotic agents, but therapeutic keratoplasty may be needed for patients whose corneal infection does not resolve. Early and accurate diagnosis, coupled with appropriate antifungal therapy, is crucial for improving the chances of complete recovery.