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J W Randles

Publications and source records attributed to J W Randles.

At least 19 recordsLinked to original sources
PubMed2006

Variants of Coconut cadang-cadang viroid isolated from an African oil palm (Elaies guineensis Jacq.) in Malaysia.

Variants of Coconut cadang-cadang viroid have been identified in a plantation oil palm growing in Malaysia. Three size classes are described, comprising 297, 293, and 270 nt. Compared with the 296-nt form of coconut cadang-cadang viroid (CCCVd), all variants substituted C31 --> U in the pathogenicity domain and A175 --> C in the right-hand terminus. Other mutations and deletions accounted for the different sizes. These are the first sequences reported for variants of Coconut cadang-cadang viroid in a species other than coconut palm, and this is the first evidence that variants closely related to CCCVd occur outside the Philippines.

Arecaceae↗
PubMed2001

Genomic heterogeneity in Pea seed-borne mosaic virus isolates from Pakistan, the centre of diversity of the host species, Pisum sativum.

A range of isolates of Pea seed-borne mosaic virus (PSbMV) was compared in the segments of the genome representing the partial NIb/CP/UTR and the partial P1-Pro/HC-Pro coding regions. Nucleotide and amino acid sequences, and a phylogenetic analysis of the CP region, divided isolates with available sequence information into two groups, one representing pathotype 4, the other pathotype 1. The pathotype 1 group showed greater diversity than the pathotype 4 group. A comparison of 14 isolates, S6 (a pathotype 4 isolate), US (a pathotype 1 isolate) and 12 isolates from Pakistan, by ribonuclease protection assay (RPA) using cRNA transcripts of the cloned partial NIb/CP/UTR regions of the S6, US and Pakistani isolate PK9 placed them into three distinct phylogenetic groups. RPA with a partial P1-Pro/HC-Pro cRNA probe identified a greater level of variation which was too high to be used for generating an overall phylogeny. Thus, RPA identified greater molecular diversity in PSbMV than described hitherto. We conclude that, in addition to the pathotypes 1 and 4 typified by US and S6 respectively, isolates of PSbMV from Pakistan include previously unrecognised molecular variants, and this accords with our previous recognition of new pathotypes from Pakistan.

Amino Acid Sequence↗
PubMed2001

The genome organisation and taxonomy of Sugarcane striate mosaic associated virus.

Sugarcane striate mosaic associated virus (SCSMaV) has slightly flexuous 950 nm x 15 nm filamentous particles and is associated with sugarcane striate mosaic disease in central Queensland, Australia. We report the full sequence of its RNA genome, which comprises 5 open reading frames representing the polymerase, movement function proteins encoded in a triple gene block and coat protein. Phylogenetic analyses based on either the full nucleotide sequence, the polymerase protein, or the coat protein all placed SCSMaV in an intermediate position between the genera Foveavirus and Carlavirus, but outside both genera. In addition, the absence of a sixth open reading frame excludes it from the genus Carlavirus, and the coat protein is approximately half the size of the type member for the genus Foveavirus. Although SCSMaV was most closely allied to Cherry green ring mottle virus by genome analysis, the two viruses are morphologically and biologically dissimilar. SCSMaV may therefore represent a new plant virus taxon.

3' Untranslated Regions↗
PubMed1997

Synthesis and two-dimensional electrophoretic analysis of mixed populations of circular and linear RNAs.

Spontaneous cleavage of the less abundant form of tobacco ringspot virus satellite RNA is readily reversible. Capitalizing on earlier observations by Feldstein and Bruening that small 'mini-monomer' RNAs derived from this molecule and containing little more than covalently attached ribozyme and substrate cleavage products are able to efficiently circularize, we have constructed a series of self-circularizing RNAs of precisely known size. Mixtures of linear and circular RNAs synthesized in vitro and containing 225-1132 nt could be completely resolved using a novel two-dimensional denaturing polyacrylamide gel electrophoresis system. Similar analyses of a complex mixture of coconut cadang-cadang viroid RNAs revealed the presence of relatively large amounts of a previously undescribed 'fast-slow' heterodimeric RNA species in infected palms. Only a single DNA template is required to prepare each pair of circular and linear RNA markers.

Base Sequence↗
PubMed1995

The promoter of coconut foliar decay-associated circular single-stranded DNA directs phloem-specific reporter gene expression in transgenic tobacco.

A full-length double-stranded DNA copy of the single-stranded circular DNA associated with coconut foliar decay virus (CFDV) was constructed. Full-length CFDV DNA and smaller fragments were transcriptionally fused to the beta-glucuronidase reporter gene and examined for promoter activity in vivo. In stably transformed tobacco plants, the CFDV DNA promoter confered a tissue-specific expression pattern in that the reporter gene was specifically expressed in the phloem tissue of the vascular system in stem, leaves and flower. These results are in agreement with the previously reported association of CFDV DNA with the phloem of its coconut host plant.

Base Sequence↗
PubMed1995

Mixed-subunit capsids can be assembled in vitro with coat protein subunits from two cucumoviruses.

Virus particles were reassembled in vitro from tomato aspermy virus strain V (V-TAV) RNA and a mixture of subunits prepared from V-TAV and 35S-labelled cucumber mosaic virus strain T (T-CMV). Immunodiffusion tests showed that the reassembled particles reacted with polyclonal antisera raised against both V-TAV and T-CMV. Radioactivity was found in the precipitin line formed between the reassembled particles and antiserum raised against T-CMV as well as in the precipitin line formed between the reassembled particles and antiserum raised against V-TAV. This shows that 35S-labelled T-CMV protein subunits were incorporated with V-TAV protein subunits into the same particles. Thus, coat proteins of V-TAV and T-CMV can co-assemble and form mixed-subunit capsids in vitro.

Capsid↗
PubMed1994

Detection of an unidentified potyvirus from Roystonea regia palm using the polymerase chain reaction and degenerate, potyvirus specific, primers and potential problems arising from the amplification of host plant DNA sequences.

Degenerate potyvirus-specific primers were used in the PCR to amplify cDNA representing a 335 nucleotide region of the coat protein gene in RNA purified from an uncharacterised potyvirus isolated from Roystonea regia palms in Queensland, Australia. The RNA was also detected by PCR in total nucleic acid extracts from infected Nicotiana benthamiana, N. clevelandii and Vicia faba. The method also successfully detected pea seed-borne mosaic virus in Pisum sativum. In addition the procedure amplified DNA's of approximately 200 bp and 420 bp, of non-viral origin, from total nucleic acid extracts of healthy Nicotiana spp, indicating that size of the PCR products needs to be included as a criterion for identifying virus specific products when this method is used.

Base Sequence↗
PubMed1991

Change in phenotype and encapsidated RNA segments of an isolate of alfalfa mosaic virus: an influence of host passage.

A local lesion isolate of alfalfa mosaic virus (AMV-N20) from lucerne was found to encapsidate two extra RNAs in addition to the four major RNAs (RNA1, -2, -3 and -4). These were resolved by gel electrophoresis both under native conditions and after glyoxal denaturation. The RNA with an electrophoretic mobility between that of RNAs 2 and 3 was designated RNA31, that between RNAs 3 and 4 was designated RNA3s. Sucrose density gradient centrifugation analysis of AMV-N20 showed six instead of the normal four nucleoprotein components, the additional two presumably representing encapsidated RNAs 31 and 3s. RNAs 31 and 3s were both shown by Northern blot hybridization to be unrelated to host plant RNA and to contain the AMV coat protein gene sequence, which resides in RNA3. Primer extension of the RNAs 31 and 3s using a primer complementary to the 3' common terminus of all genomic AMV RNAs provided further evidence that they contained AMV sequences. RNA31 represents an addition of about 255 nucleotides, compared with RNA3, and RNA3s represents a loss of about 308 nucleotides. The coat proteins of variants encapsidating either RNA31, -3 or -3s had the same Mr indicating that the addition or deletion of the nucleotides was outside the coat protein gene. Serial mechanical passage of AMV-N20 over 5 years in four host species led both to changes in the composition of the RNA3 mixture, and to changes in symptom severity. For example, following passage in Nicotiana clevelandii, RNA3 was lost whereas passage in either N. glutinosa, Chenopodium quinoa or C. amaranticolor resulted in the loss of RNA31. No association was found between the changes in RNA3 and phenotypic changes that resulted from continuous passage for 5 years. Phenotypic changes with passage are thus presumably determined by mutations elsewhere in the virus genome.

Blotting, Northern↗
PubMed1990

Nucleotide sequence of a circular single-stranded DNA associated with coconut foliar decay virus.

A circular single-stranded (ss) covalently closed (ccc) DNA associated with coconut foliar decay virus (CFDV) was purified, amplified by the polymerase chain reaction, and subcloned and its sequence established by analysis of overlapping subgenomic cDNA clones. The complete CFDV sequence comprised 1291 nucleotides and contained open reading frames for six proteins of molecular weight larger than 5 kDa. One of these (ORF1, 33.4 kDa) codes for a leucine-rich protein with the nucleoside triphosphate-binding motif GXGKS and may possibly participate in virus replication. The putative viral protein encoded by ORF3 (6.4 kDa) is a positively charged arginine-rich protein with homology to the capsid protein of nuclear polyhedrosis virus, and may represent the CFDV coat protein. CFDV DNA can form a stable stem structure of 10 GC base pairs subtending a loop sequence which in one orientation closely resembles the motif TAATATTAC conserved in a similar structural arrangement within the geminivirus group. Otherwise no sequence homology to DNA-containing plant viruses of the gemini- or caulimovirus groups was found. CFDV therefore represents a new taxonomic group of plant viruses.

Amino Acid Sequence↗
PubMed1990

Nicotiana velutina mosaic virus: evidence for a bipartite genome comprising 3 kb and 8 kb RNAs.

DNA complementary to Nicotiana velutina mosaic virus (NVMV) RNA was cloned and five segments larger than 0.9 kb were used in Northern blot hybridization analysis to identify two virus-specific RNAs, approximately 8 kb (RNA 1) and 3 kb (RNA 2) in size. The clones selected as probes did not hybridize with RNA from various tobamoviruses, or from beet necrotic yellow vein (BNYVV) and peanut clump furoviruses. In an attempt to determine the taxonomic position of the virus, about 75% of the NVMV RNA 2 was sequenced and four open reading frames (ORFs) were identified. ORFs 1, 2 and 3 encode proteins of Mr 20K, 39K and 13K, whereas ORF 4 was incomplete. ORFs 2, 3 and 4 overlapped in an arrangement closely resembling the triple gene block identified in BNYVV RNA 2, barley stripe mosaic virus (BSMV) RNA 2, potato virus X and potato virus M RNA. The presumed coat protein gene of NVMV RNA 2 (ORF 1) is situated to the 5' side of the triple gene block as for BNYVV and BSMV RNA 2. Amino acid homologies were detected among the 13K and 14K proteins of NVMV RNA 2, BNYVV RNA 2 and BSMV RNA 2. Significant homology was also detected between the 39K protein of NVMV RNA 2 and the 42K protein of BNYVV RNA 2, with a motif specific for ATP- and GTP-binding (NTP-binding motif), and a conserved viral DNA polymerase domain. The presence of a triple gene block in NVMV RNA 2 indicates that NVMV has affinities with members of the hordei-, furo-, potex- and carlavirus groups but not with the tobamovirus group. The divided RNA genome of NVMV, and the sizes of the two RNAs suggest that NVMV is most closely allied to the furoviruses, but the unique nature of its different biological properties and lack of any serological relationships with furoviruses lead us to conclude that NVMV has no clear relatedness to any taxonomic group of plant viruses.

Amino Acid Sequence↗
PubMed1990

Isolation of a subterranean clover mottle virus-like satellite RNA from lucerne infected with lucerne transient streak virus.

A circular, viroid-like satellite RNA (sat RNA) was detected in lucerne transient streak virus (LTSV), from lucerne in South Australia. It was larger than the previously reported sat RNA of LTSV, being similar in size and sequence homology to the 388 nucleotide sat RNA previously shown to be encapsidated by subterranean clover mottle virus (SCMoV) isolated from subterranean clover in Western Australia. This indicates that under field conditions, very similar sat RNAs can be associated with two distantly related sobemoviruses, LTSV and SCMoV. The natural hosts of these viruses are lucerne and subterranean clover, respectively.

Australia↗
PubMed1989

Coconut foliar decay virus particles are 20-nm icosahedra.

A small single-stranded circular DNA has previously been reported to be associated with foliar decay disease of coconut palm in Vanuatu. Here we describe the isolation of unusual 20-nm icosahedral particles which copurify with foliar decay disease DNA and which we consider to be the coconut foliar decay virus. This virus seems to represent a novel group of plant viruses.

Cocos↗
PubMed1988

Cadang-cadang disease of coconut palm.

Cadang-cadang disease has caused the death of over 30 million coconut palms, and no control measures are known. The causal viroid is the smallest known pathogen. Field diagnostic tests will soon be developed to allow mapping of the distribution and spread of the viroid and this should lead to the identification of appropriate control measures.

Base Sequence↗
PubMed1986

Single antibody dot immunoassay--a simple technique for rapid detection of a plant virus.

A single antibody dot immunoassay (SADI) was developed for use as a rapid, simple and sensitive technique for the direct assay of virus bound to nitrocellulose membranes. SADI has been tested for the detection of subterranean clover mottle virus (SCMoV) in small amounts of infected tissue and purified virus preparations, and the technique was found to be twelve times more sensitive than ELISA in terms of total antigen detected. DIBA, an indirect dot immunoassay, was about twice as sensitive as SADI, but the latter was more specific for the detection of SCMoV and is a simpler, more rapid assay, requiring less than three h to complete.

Animals↗