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P Hooley

Publications and source records attributed to P Hooley.

11 recordsLinked to original sources
PubMed2004

Human endogenous retroviruses: transposable elements with potential?

Human endogenous retroviruses (HERVs) are a significant component of a wider family of retroelements that constitute part of the human genome. These viruses, perhaps representative of previous exogenous retroviral infection, have been integrated and passed through successive generations within the germ line. The retention of HERVs and isolated elements, such as long-terminal repeats, could have the potential to harm. In this review we describe HERVs within the context of the family of known transposable elements and survey these viruses in terms of superantigens and molecular mimics. It is entirely possible that these mechanisms provide the potential for undesired immune responses.

DNA Transposable Elements↗
PubMed2003

Demystified. Human endogenous retroviruses.

Human endogenous retroviruses (HERVs) are a family of viruses within our genome with similarities to present day exogenous retroviruses. HERVs have been inherited by successive generations and it is possible that some have conferred biological benefits. However, several HERVs have been implicated in certain cancers and autoimmune diseases. This article demystifies these retroviruses by providing an insight into HERVs, their means of classification, and a synopsis of HERVs implicated in cancer and autoimmunity. Furthermore, the biological roles of HERVs are explored.

Antibodies, Viral↗
PubMed2001

Variation between two near isogenic barley (Hordeum vulgare) cultivars in expression of the B subunit of the vacuolar ATPase in response to salinity.

A gene encoding the barley vacuolar ATPase subunit B (BSVAP) was differentially expressed between two near isogenic barley cultivars, Golden Promise and Maythorpe. This gene (BSVAP) was isolated by the mRNA differential display technique (DDRT-PCR). BSVAP was salt inducible under long-term salinity stress in the salt sensitive cultivar Maythorpe but less so in the relatively salt tolerant Golden Promise and was more highly expressed under control conditions in Maythorpe. The physiological consequences of altered vacuolar ATPase expression are discussed in relation to the salt sensitivity of Maythorpe.

Adenosine Triphosphatases↗
PubMed1999

Cloning and characterisation of the sagA gene of Aspergillus nidulans: a gene which affects sensitivity to DNA-damaging agents.

Mutations within the sagA gene of Aspergillus nidulans cause sensitisation to DNA-damaging chemicals but have no effect upon spontaneous or damage-induced mutation frequency. The sagA gene was cloned on a 19-kb cosmid-derived fragment by functional complementation of a sagA1 sagC3 double mutant; subsequently, a fragment of the gene was also isolated on a 3.9-kb genomic subclone. Initial sequencing of a small section of the 19-kb fragment allowed the design of primers that were subsequently used in RTPCR experiments to show that this DNA is transcribed. A 277-bp fragment derived from the transcribed region was used to screen an A. nidulans cDNA library, resulting in the isolation of a 1.4-kb partial cDNA clone which had sequence overlap with the genomic sagA fragment. This partial cDNA was incomplete but appeared to contain the whole coding region of sagA. The sagA1 mutant was shown to possess two mutations; a G-T transversion and a+ 1 frameshift due to insertion of a T. causing disruption to the C-terminal region of the SagA protein. Translation of the sagA cDNA predicts a protein of 378 amino acids, which has homology to the Saccharomyces cerevisiae End3 protein and also to certain mammalian proteins capable of causing cell transformation.

Alkylating Agents↗
PubMed1997

Genetic and molecular characterization of murine GATA-1 in Aspergillus defines a critical role for the N-terminal finger.

We have utilized Aspergillus nidulans as a model system for the characterization of the major vertebrate transcription factor GATA-1. This has been achieved both by analysing the function of murine GATA-1 directly and by using direct gene replacement to introduce chimaeric areA::GATA-1 derivatives at the areA locus, which encodes a GATA factor involved in regulating nitrogen metabolism in A. nidulans. Although GATA-1 shows only limited function when expressed in A. nidulans, the C-terminal GATA DNA-binding domain can replace the native GATA domain of AREA and retain near wild-type function. Surprisingly, inclusion of the N-terminal DNA-binding domain of GATA-1 has a major role in determining the function of areA::GATA constructs in vivo, leading to a general loss of activation. This negative function is partially dominant and is dependent on both the fidelity of the zinc-chelating structure and a second factor encoded by A. nidulans. The presence of two GATA domains also disrupts modulation of AREA activity. The ability of duplicate GATA domains to disrupt normal signal transduction is not dependent on the relative position of the domains or on the fidelity of the zinc-chelating structure. This demonstrates the utility of nitrogen metabolism's regulation in A. nidulans as a model system for the molecular and genetic characterization of heterologous GATA factors while also providing insights into native Aspergillus regulatory components.

Amino Acid Sequence↗
PubMed1996

Evidence for sltA1 as a salt-sensitive allele of the arginase gene (agaA) in the ascomycete Aspergillus nidulans.

Strains of Aspergillus nidulans carrying the sltA1 mutation, conferring sensitivity to KCl and NaCl, also showed an arginine-sensitive phenotype whereby concentrations of the L-amino acid at or above 10 mM were toxic to growth. Sexual progeny of a cross between a sltA1 mutant and a wild-type strain showed a co-segregation of salt and arginine sensitivity. Similarly, revertants to salt tolerance showed a loss of arginine sensitivity as did sltA1 strains that were transformed with a cosmid carrying the putative sltA1+ wild-type allele. In addition, arginine sensitivity could be relieved by L-ornithine. It is suggested that sltA1 is a salt-sensitive allele of the arginase gene (agaA).

Alleles↗
PubMed1988

An adaptive response to alkylating agents in Aspergillus nidulans.

A simple method is described for demonstrating adaptation to alkylation damage in Aspergillus nidulans. One wild type, two MNNG-sensitive, and one MNNG-resistant strain all showed improvement in colony growth when challenged with MNNG following appropriate inducing pretreatments. Other alkylating agents (MMS, EMS) could also adapt mycelium to later MNNG challenge, while 4NQO and UV could not. The inducible effect was not transmissible through conidia. A standard reversion assay based upon methG proved impractical for studying mutation frequencies during alkylation treatments owing to variations in MNNG resistance amongst revertants.

Adaptation, Physiological↗
PubMed1988

Mutants of Aspergillus nidulans with increased resistance to the alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine.

The isolation and characterisation of mutants of Aspergillus nidulans showing resistance to MNNG is described. Such isolates were stable through prolonged subculture in the absence of the selective agent, and resistance segregated as an allele of a single gene in meiotic and mitotic analysis. MNNG-resistant strains showed an increase in resistance to EMS and UV irradiation but no cross-resistance to MMS was detected. Possible mechanisms of resistance to alkylating agents are discussed.

Aspergillus nidulans↗