Endophytic fungal entomopathogens with activity against plant pathogens: ecology and evolution

Dual biological control, of both insect pests and plant pathogens, has been reported for the fungal entomopathogens, Beauveria bassiana (Bals.-Criv.) Vuill. (Ascomycota: Hypocreales) and Lecanicillium spp. (Ascomycota: Hypocreales). However, the primary mechanisms of plant disease suppression are different for these fungi. Beauveria spp. produce an array of bioactive metabolites, and have been reported to limit growth of fungal plant pathogens in vitro. In plant assays, B. bassiana has been reported to reduce diseases caused by soilborne plant pathogens, such as Pythium, Rhizoctonia, and Fusarium. Evidence has accumulated that B. bassiana can endophytically colonize a wide array of plant species, both monocots and dicots. B. bassiana also induced systemic resistance when endophytically colonized cotton seedlings were challenged with a bacterial plant pathogen on foliage. Species of Lecanicillium are known to reduce disease caused by powdery mildew as well as various rust fungi. Endophytic colonization has been reported for Lecanicillium spp., and it has been suggested that induced systemic resistance may be active against powdery mildew. However, mycoparasitism is the primary mechanism employed by Lecanicillium spp. against plant pathogens. Comparisons of Beauveria and Lecanicillium are made with Trichoderma, a fungus used for biological control of plant pathogens and insects. For T. harzianum Rifai (Ascomycota: Hypocreales), it has been shown that some fungal traits that are important for insect pathogenicity are also involved in biocontrol of phytopathogens.     

Identification of the allelic state of the <Emphasis Type="Italic">Lr34</Emphasis> leaf rust resistance gene in soft winter wheat cultivars developed in Ukraine

The distribution of alleles at the Lr34 locus associated with leaf rust resistance has been studied in soft winter wheat (Triticum aestivum L.) cultivars developed in Ukraine. To determine the allelic state of the Lr34 locus, codominant molecular marker cssfr5 has been used. Cultivars with the revealed Lr34(+) and Lr34(−) alleles have been identified as potentially resistant or susceptible, respectively. A collection of 81 cultivars from the main breeding centers of Ukraine has been examined; the Lr34(+) allele has been revealed in 44% of the tested cultivars. The obtained results have been compared with general data on the leaf rust resistance of wheat cultivars from different countries.     

Premeiotic disruption of the Neurospora crassa malate synthase gene by native and divergent DNAs

Summary Repeat-induced point mutation (RIP) has been used to generate new mutations in the previously uncharacterised gene for malate synthase in Neurospora crassa. Molecular clones carrying the am (NADP-glutamate dehydrogenase) gene and the malate synthase gene from either N. crassa or Aspergillus nidulans have been introduced into Neurospora as ectopic duplicate copies by transformation, selecting for the am function in a deletion host. A number of meiotic progeny derived from these transformants were unable to use acetate as sole carbon source, yielded no detectable malate synthase activity and demonstrated extensive cytosine methylation of their duplicated sequences. The new locus has been designated acu-9 and has been assigned to linkage group VII.     

Drosophila learning and memory: Recent progress and new approaches

The processes of learning and memory have traditionally been studied in large experimental organisms (Aplysia, mice, rats and humans), where well-characterized behaviors are easily tested. Although Drosophila is one of the most experimentally tractable organisms, it has only recently joined the others as a model organism for learning and memory. Drosophila behavior has been studied for over 20 years; however, most of the work in the learning and memory field has focused on initial learning, because establishing memory in Drosophila has not been as straightforward as in other organisms. A major recent advance in this field has been the development of a training protocol that induces long-term memory in flies. This made possible experiments that implicated the Drosophila CREB gene as a critical component in the consolidation of long-term memory, and paves the way for future experiments utilizing the well developed tools in Drosophila. This review will briefly summarize what is known in the field of Drosophila learning and memory to date, and discuss why the unique aspects of this field make traditional approaches difficult and reward the use of alternative paths of experimentation.     

Serum repressing efflux pump CDR1 in Candida albicans

Background  

In the past decades, the prevalence of candidemia has increased significantly and drug resistance has also become a pressing problem. Overexpression of CDR1, an efflux pump, has been proposed as a major mechanism contributing to the drug resistance in Candida albicans. It has been demonstrated that biological fluids such as human serum can have profound effects on antifungal pharmacodynamics. The aim of this study is to understand the effects of serum in drug susceptibility via monitoring the activity of CDR1 promoter of C. albicans.     

An In Situ Pig Liver Esterase Assay as a Useful Predictive Tool for the Likely In Vitro Anti Viral Activity of Phosphoramidate Pro-Drugs

Abstract

The pig liver esterase (PLE) assay has been designed to ?reproduce? in vitro the first step of the metabolism of phosphoramidate pro-drugs that generates the free amino acyl phosphoramidate intermediate which has been described as a key metabolite necessary but not sufficient for the biological activity. The method could be used as a predictive tool for the likely in vitro biological activity as well as for Structure—Activity Relationship establishment (SAR).     

Studies in aquatic fungi of Varanasi IV. new records and notes on taxonomy

Summary In continuation with the studies in aquatic fungi of Varanasi, four more fungi viz., Achlya apiculata, A. oblongata var. oblongata, Blastocladiella simplex and Pythiogeton ramosum have been isolated and described as occurring new to the Indian aquatic flora; while P. sterilis has been assigned to synonymy under P. ramosum Hamid's isolate A. oblongata var. oblongata has been excluded from the valid identification.     

pTn5cat:A Tn5-Derived Genetic Element to Facilitate Insertion Mutagenesis, Promoter Probing, Physical Mapping, Cloning, and Marker Exchange in Phytopathogenic and Other Gram-Negative Bacteria

A Tn5-derived mobile element has been constructed to identify genes and promoters related to pathogenesis and virulence inPseudomonas syringaepv.phaseolicola.To enhance the rate of mutation this Tn5derivative was constructed carrying a mutant transposase which was placed incisto the transposable element, but just outside the inverted repeats, therefore eliminating secondary transposition and increasing the stability of the insertion. The new element also contains a promoterlesscat(chloramphenicol acetyltransferase) gene as reporter to allow for positive selection of promoters being expressed under specific conditions. To facilitate cloning and manipulations inEscherichia coli,a ColE1 origin of replication has been included within the transposable element as well as the Mob region from the broad-host-range plasmid RP4, which allows this element to be efficiently mobilized by a triparental mating or by using anE. colistrain such as S17-1 to provide thetrafunctions. Sites for the rare cuttersPacI andPmeI have also been included to facilitate locating the insertions on aPacI and/orPmeI physical map. This construction combines the properties of both a mobilizable plasmid and a transposon and therefore has been termed pTn5cat.It is almost the same size as the wild-type Tn5, 5877 bp, and has successfully been tested inP.s. phaseolicolaandXanthomonas campestrispv.campestris.     

Genetics of esterases in Drosophila of the virilis group. I. Characteristics of esterase patterns in D. virilis,D. texana,D. littoralis,and their hybrids

Starch and polyacrylamide gel electrophoreses have detected six esterase fractions in Drosophila of the virilis group. These esterases have been characterized in detail using a series of substrates and inhibitors and also thermal treatment. Differences in esterase patterns have been found between D. virilis, D. texana, and D. litoralis as well as between D. virilis stocks. An interstock polymorphism for different esterase patterns has been established with respect to the electrophoretic mobilities of a number of esterase fractions. In rare instances, it has been observed within some D. virilis stocks, too. There is specificity in organ distribution of esterase fractions in Drosophila. Monogenic control of the electrophoretic mobilities of esterase-2 and esterase-4 has been demonstrated in D. virilis, and a dimer structure has been found in esterase-2. Genes controlling esterase-2 and esterase-4 are located on the second chromosome (209.3 for esterase-2 and 192.0 for esterase-4). In interstock and interspecific hybrids, esterases usually manifest codominance. In interstock hybrids, esterase-2 forms a hybrid band not observed in interspecific hybrids. In third instar larvae of interspecific hybrids, differential expression of certain esterase isozymes has been noted. These observations are in agreement with data from histochemical studies of organs of different hybrids.     

Uncover Genetic Interactions in Caenorhabditis elegans by RNA Interference

RNA-mediated interference (RNAi) has emerged recently as one of the most powerful functional genomics tools. RNAi has been particularly effective in the nematode worm C. elegans where RNAi has been used to analyse the loss-of-function phenotypes of almost all predicted genes. In this review, we illustrate how RNAi has been used to analyse gene function in C. elegans as well as pointing to some future directions for using RNAi to examine genetic interactions in a systematic manner.     

The Effect of Shear on the Desorption of Liposomes Adsorbed to Bacterial Biofilms

Abstract

With the aid of a flow cell assembly the desorption of cationic liposomes prepared from mixtures of dipalmitoylphoshatidylcholine (DDPC), cholesterol, and either dimethyldioctadecylammonium bromide (DDAB) or 3,β[N-(N¹,N-dimethylethylenediamine)-carbamoyl]cholesterol (DC-chol) from immoblized biofilms of Staphylococcus aureus has been studied as a function of shear stress by confocal microscopy. A shear stress theory has been adapted from fluid mechanics of laminar flow between parallel plates and used to determine the critical shear stress for liposome desorption. The critical shear stress for both DDAB and DC-chol liposomes has been determined as a function of cationic lipid content and hence surface charge as reflected in their zeta potentials. The critical shear stress has been used to obtain the potential energy of liposome–biofilm interaction which together with the electrostatic interaction energy has enabled estimates of the London-Hamaker constants to be made. The values of the London-Hamaker constants at small liposome-bacterial cell separation were found to be independent of liposome composition.     

Familial Juvenile Hyperuricaemic Nephropathy is not Such a Rare Genetic Metabolic Purine Disease in Britain

Renal disease is rare today in classic adult gout, and gout is rare in renal disease—especially in the young. Here we summarise studies in 158 patients from 31 kindreds diagnosed with familial juvenile hyperuricaemic nephropathy FJHN from a total of 230 kindred members studied in Great Britain. Some patients have been followed for up to 30 years, and allopurinol has ameliorated the progression of the renal disease in all 113 surviving members provided: 1. They have been diagnosed and treated sufficiently early.

2. Compliance with allopurinol treatment and diet has been as important as early recognition.

3. Hypertension has been rigorously controlled.

4. The use of oral contraceptives has been avoided, as has pregnancy in any female with a Glomelar Filtration Rate GFR <70 ml/min.

The question arising is: Why is FJHN the most prevalent genetic purine disorder diagnosed in Britain? Is it a lack of awareness which needs to be improved Europe-wide?     

Genetics of naphthalene and phenanthrene degradation by Comamonas testosteroni

Naphthalene and phenanthrene have long been used as model compounds to investigate the ability of bacteria to degrade polycyclic aromatic hydrocarbons. The catabolic pathways have been determined, several of the enzymes have been purified to homogeneity, and genes have been cloned and sequenced. However, the majority of this work has been performed with fast growing Pseudomonas strains related to the archetypal naphthalene-degrading P. putida strains G7 and NCIB 9816-4. Recently Comamonas testosteroni strains able to degrade naphthalene and phenanthrene have been isolated and shown to possess genes for polycyclic aromatic hydrocarbon degradation that are different from the canonical genes found in Pseudomonas species. For instance, C. testosteroni GZ39 has genes for naphthalene and phenanthrene degradation which are not only different from those found in Pseudomonas species but are also arranged in a different configuration. C. testosteroni GZ42, on the other hand, has genes for naphthalene and phenanthrene degradation which are arranged almost the same as those found in Pseudomonas species but show significant divergence in their sequences. Received 10 August 1997/ Accepted in revised form 15 August 1997     

In silico genome-scale metabolic analysis of Pseudomonas putida KT2440 for polyhydroxyalkanoate synthesis,degradation of aromatics and anaerobic survival

Genome-scale metabolic models have been appearing with increasing frequency and have been employed in a wide range of biotechnological applications as well as in biological studies. With the metabolic model as a platform, engineering strategies have become more systematic and focused, unlike the random shotgun approach used in the past. Here we present the genome-scale metabolic model of the versatile Gram-negative bacterium Pseudomonas putida, which has gained widespread interest for various biotechnological applications. With the construction of the genome-scale metabolic model of P. putida KT2440, PpuMBEL1071, we investigated various characteristics of P. putida, such as its capacity for synthesizing polyhydroxyalkanoates (PHA) and degrading aromatics. Although P. putida has been characterized as a strict aerobic bacterium, the physiological characteristics required to achieve anaerobic survival were investigated. Through analysis of PpuMBEL1071, extended survival of P. putida under anaerobic stress was achieved by introducing the ackA gene from Pseudomonas aeruginosa and Escherichia coli.     

Studies on the effect of feeding some freshwater fishes with Scenedesmus obliquus (Turpin) Kuetzing

Summary The effect of feeding S. obliquus on two freshwater fishes Puntius ticto and Trichogaster fasciatus has been studied. It is observed that there is overall improvement in the conditions of the fishes and a marked increase in weight, volume and measurements has been observed as compared to control.     

Genetics and physiology of the rel system of Bacillus subtilis

Summary Stringent factor (ATP:GTP-3 pyrophosphotransferase) has been purified from wild type Bacillus subtilis and it has been shown that guanosine tetra- and pentaphosphate (ppGpp and pppGpp) are synthesized in vitro in the presence of ribosomes, unacylated tRNA and its specific codon, as has been demonstrated in Escherichia coli. relA, the genetic determinant for the stringent factor, has been mapped on the B. subtilis chromosome by transduction and is found between aroD and leu.The relC locus, defined by mutations which were originally selected by resistance to thiostrepton, has been mapped adjacent to spoOH in the order cysA, spoOH, relC, rif.Stringent factor and ribosomes are functional for the in vitro synthesis of (p)ppGpp in early stages of sporulation (up to at least 4 h). This contradicts the findings of other laboratories.     

Ricerche Embriologiche Sul Genere Thalictrum. II. Embriologia e Cariologia Di Thalictrum Lucidum L. e di Thalictrum Minus L. Subsp. Minus

Abstract

Embryological researches in the «Thalictrum» genus. II. Embryology and caryology of «Thalictrum lucidum» L. and «Thalictrum minus» L. ssp. «minus». — In their development the female gametophytes of Thalictrum lucidum L. and Thalictrum minus L. ssp. minus follow the Normal type. In the female gametophytes of these species several types of antipodal cells occurs such as: their considerable enlargement, formation of many antipodals polyploid or polinucleated antipodal cells. In these various types, however, a rapid regression of the antipodals occurs. In T. lucidum some tendency to a disposition of the tetrapolarized type has been verified. The chromosome number has been confirmed to ben 2n=28 in besides, in the pollen development, many cases of regression of the microspores has been verified. The chromosome number has been confirmed to ben 2n=28 in Thalictrum lucidum L., and has been found to ben 2n=14 in Thalictrum minus L. ssp. minus, a new number in this species, which was earlier reported to have 2n=42.     

Rhodothermus marinus: physiology and molecular biology

Rhodothermus marinus has been the subject of many studies in recent years. It is a thermohalophilic bacterium and is the only validly described species in the genus Rhodothermus. It is not closely related to other well-known thermophiles and is the only thermophile within the family Crenotrichaceae. R. marinus has been isolated from several similar but distantly located geothermal habitats, many of which are subject to large fluctuations in environmental conditions. This presumably affects the physiology of R. marinus. Many of its enzymes show optimum activity at temperatures considerably higher than 65°C, the optimum for growth, and some are active over a broad temperature range. Studies have found distinguishing components in the R. marinus electron transport chain as well as in its pool of intracellular solutes, which accumulate during osmotic stress. The species hosts both bacteriophages and plasmids and a functional intein has been isolated from its chromosome. Despite these interesting features and its unknown genetics, interest in R. marinus has been mostly stimulated by its thermostable enzymes, particularly polysaccharide hydrolysing enzymes and enzymes of DNA synthesis which may be useful in industry and in the laboratory. R. marinus has not been amenable to genetic analysis until recently when a system for gene transfer was established. Here, we review the current literature on R. marinus.