Biomedical subjects

Robert G Shatters

Publications and source records attributed to Robert G Shatters.

5 recordsLinked to original sources

PubMed2006

Phylogenetic and structural relationships of the PR5 gene family reveal an ancient multigene family conserved in plants and select animal taxa.

Pathogenesis-related group 5 (PR5) plant proteins include thaumatin, osmotin, and related proteins, many of which have antimicrobial activity. The recent discovery of PR5-like (PR5-L) sequences in nematodes and insects raises questions about their evolutionary relationships. Using complete plant genome data and discovery of multiple insect PR5-L sequences, phylogenetic comparisons among plants and animals were performed. All PR5/PR5-L protein sequences were mined from genome data of a member of each of two main angiosperm groups-the eudicots (Arabidoposis thaliana) and the monocots (Oryza sativa)-and from the Caenorhabditis nematode (C. elegans and C. briggsase). Insect PR5-L sequences were mined from EST databases and GenBank submissions from four insect orders: Coleoptera (Diaprepes abbreviatus and Biphyllus lunatus), Orthoptera (Schistocerca gregaria), Hymenoptera (Lysiphlebus testaceipes), and Hemiptera (Toxoptera citricida). Parsimony and Bayesian phylogenetic analyses showed that the PR5 family is paraphyletic in plants, likely arising from 10 genes in a common ancestor to monocots and eudicots. After evolutionary divergence of monocots and eudicots, PR5 genes increased asymmetrically among the 10 clades. Insects and nematodes contain multiple sequences (seven PR5-Ls in nematodes and at least three in some insects) all related to the same plant clade, with nematode and insect sequences separating as two clades. Protein structural homology modeling showed strong similarity among animal and plant PR5/PR5-Ls, with divergence only in surface-exposed loops. Sequence and structural conservation among PR5/PR5-Ls suggests an important and conserved role throughout the evolutionary divergence of the diverse organisms from which they reside.

Amino Acid Sequence↗

PubMed2005

Developmental changes in abundance of the VSPbeta protein following nuclear transformation of maize with the soybean vspbeta cDNA.

BACKGROUND: Developing monocots that accumulate more vegetative tissue protein is one strategy for improving nitrogen-sequestration and nutritive value of forage and silage crops. In soybeans (a dicotyledonous legume), the vspA and B genes encode subunits of a dimeric vegetative storage protein that plays an important role in nitrogen storage in vegetative tissues. Similar genes are found in monocots; however, they do not accumulate in leaves as storage proteins, and the ability of monocot leaves to support accumulation of an ectopically expressed soybean VSP is in question. To test this, transgenic maize (Zea Mays L. Hi-II hybrid) lines were created expressing soybean vspB from a maize ubiquitin Ubi-1 promoter. RESULTS: From 81 bombardments, 101 plants were regenerated, and plants from five independent lines produced vspB transcripts and VSPbeta polypeptides. In leaves from seven-week-old plants (prior to flowering), VSPbeta accumulated to 0.5% of the soluble leaf protein in primary transgenic plants (R0), but to only 0.03% in R1 plants. During seed-filling (silage-stage) in R1 plants, the VSPbeta protein was no longer detected in leaves and stems despite continued presence of the vspB RNA. The RNA transcripts for this peptide either became less efficiently translated, or the VSPbeta protein became unstable during seed-fill. CONCLUSION: Developmental differences in the accumulation of soybean VSPbeta when transgenically expressed in maize show that despite no changes in the vspB transcript level, VSPbeta protein that is readily detected in leaves of preflowering plants, becomes undetectable as seeds begin to develop.

Blotting, Northern↗

PubMed2005

Differential transcriptional activity of plant-pathogenic begomoviruses in their whitefly vector (Bemisia tabaci, Gennadius: Hemiptera Aleyrodidae).

Plant-pathogenic begomoviruses have a complex association with their whitefly vector and aspects concerning virus genetic activity (genome replication and gene transcription) within the insect remain highly controversial. Virus transcript abundance was assessed by quantifying selected gene transcripts of Tomato mottle virus (ToMoV, a New World bipartite begomovirus) and Tomato yellow leaf curl virus (TYLCV, an Old World monopartite begomovirus) in whiteflies (Bemisia tabaci biotype B) after feeding on virus-infected tomato plants and after subsequent transfer to cotton, a plant that is immune to the selected begomoviruses. Real-time RT-PCR was performed using specific primers for three ToMoV genes (AV1, BC1 and BV1) and three TYLCV genes (V1, V2 and C3). The ToMoV gene transcripts rapidly became undetectable in whiteflies following transfer from tomato to cotton, probably because degradation was not accompanied by new synthesis. On the other hand, TYLCV transcripts increased after transfer of whiteflies to cotton, indicating active TYLCV transcription. Interestingly, the difference observed in ToMoV and TYLCV transcripts in the vector parallel observations on the different biological effects of these viruses on whiteflies, i.e. TYLCV, but not ToMoV, reduces whitefly fitness.

Animals↗

PubMed2004

Putative protease inhibitor gene discovery and transcript profiling during fruit development and leaf damage in grapefruit (Citrus paradisi Macf.).

Seven putative protease inhibitor (PPI) cDNAs, representing four protein families, were isolated from a grapefruit (Citrus paradisi Macf. Cv. Marsh) immature fruit flavedo cDNA library. Cloned open reading frames encoded proteins with similarity to, and protein signatures for: legume Kuntiz inhibitors (lkiL-1, lkiL-2, lkiL-3), potato trypsin inhibitor I (ptiIL-1), serpins (serpL-1), cystatins (cystL-1), and gamma thionins (gthL-1). Response of transcript abundance to fruit development and leaf wounding was determined for all but lkiL-1 using real-time RT-PCR. Immature leaves had the highest transcript levels for all PPIs. The gthL-1 transcript in immature leaves was the most abundant transcript but was absent from healthy mature leaves. In fruit flavedo, transcripts for all PPIs were most abundant in youngest fruit (<15 mm dia. fruit), and declined during development, but displayed different patterns of developmental change. Mechanical or Diaprepes root weevil (DRW) feeding damage to leaves caused a <10-fold reduction or had no effect on transcript level with the exception of gthL-1 which, as a result of damage, increased >50-fold in mature leaves and decreased >1400-fold in immature leaves. This developmental control of transcript response to wounding in a woody perennial is opposite of what has been observed for defensive proteinase inhibitors (PIs) in other plants (typically herbaceous and/or annual plants), where younger leaves typically invoke a higher defensive proteinase inhibitor transcript accumulation than older tissues. Except for gthL-1, the PPI transcripts were minimally responsive or unresponsive to wounding. Changes in PPI transcript levels suggest diverse roles for the products of these genes in citrus, with only gthL-1 responding in a defense-like manner.

Citrus↗

PubMed2002

Effect of geminivirus infection and Bemisia infestation on accumulation of pathogenesis-related proteins in tomato.

The whitefly, Bemisia tabaci biotype B, has been shown to cause pathogenesis-related (PR) proteins to accumulate in plants as a result of direct feeding, but their specific role in plant defensive systems is unclear. Our objective was to compare accumulation of tomato PR proteins (beta-1,3-glucanase, chitinase, peroxidase, P2 and P4) in response to whitefly, with or without tomato mottle virus (ToMoV) infection. Tomato PR protein response was measured over time in plants divided into three treatments: uninfected controls (with or without whiteflies) and plants infested with viruliferous (ToMoV) whiteflies. Five- to six-leaf plants were infested with approximately 5 adult whitefly per leaf. Plants were sampled prior to whitefly infestation and at 14, 28, 42, and 56 days. By 56 days, plants infested with viruliferous whiteflies had significantly more eggs (2.5-fold) and nymphs (4.5-fold) than plants with nonviruliferous whiteflies. A significant increase in the enzymatic activity of all measured PR proteins, as compared to control plants, was only seen in viruliferous whitefly-infested plants. No significant difference was observed in enzyme activities between the uninfected control plants either with or without whiteflies. The greatest differences for all PR proteins assayed were observed 42 days after treatment initiation. Protein blot analyses showed that the differences in PR protein activities among the treatments were due to changes in specific enzyme levels within the plant and were associated with concomitant increases in levels of P2 and P4 PR proteins. Under our experimental conditions, it is clear that PR protein response is much more intense when it is attacked by whiteflies carrying ToMoV than by whitefly alone.

Animals↗