bluuebunny/crossref_metadata_2025 huggingface dataset:
Dissolution of type I collagen fibrils by gingival fibroblasts isolated from patients of various periodontitis categories
Authors: Havemose‐Poulsen Anne , Holmstrup Palle , Stoltze Kaj , Birfcedal‐Hansen Henning
Published: July 2006

The classification of periodontitis in various disease categories, including juvenile periodontitis, rapidly progressive adult periodontitis and slowly progressive adult periodontitits is based mainly on differences in disease progresssion and age group susceptibility. Because dissolution of collagen fibers is an integral part of periodontal attachment loss, we investigated whether the clinical differences among these periodontitis/control groups are reflected in the collagen‐degrading activity of gingival fibroblasts isolated from affected tissues. All fibroblast strains isolated from the 4 groups (n=48) displayed cell‐associated collagenolytic activity when seeded in contact with a reconstituted film of type I collagen fibrils. Cells from the control group (n=14) dissolved the collagen fibril film twice as fast as those from each of the 3 disease groups (juvenile periodontitis (n=13), rapidly progressive adult periodontitis (n=7), and slowly progressive adult periodontitits (n=14)). Both interleukin‐1β and phorbolester accelerated the rate of dissolution 2–4‐fold, but even after cytokine or phorbolester stimulation control cells were still considerably more effective in dissolving the collagen fibrils than cells from the disease groups. The observation made in this study, that dissolution of collagen fibrils by gingival fibroblasts from periodontally diseased individuals is significantly slower than by cells from healthy control subjects, challenges disease paradigm: based on a direct relationship between collagenolytic potential and disease activity.
In vitro modulation of human gingival epithelial cell attachment and migration by minocycline‐HCI
Authors: Vanheusden A. , Nusgens B. , Goffinet G. , Zahedi S. , Lapière C. M. , Rompen E.
Published: July 2006

Although the influence of tetracyclines on periodontal connective tissue cells has been the topic of many in vitro and in vivo studies, data regarding their effects on gingival epithelial cells are scarce. The present in vitro study was designed to examine the influence of minocycline, a semi‐synthetic analog of tetracycline, on human gingival keratinocyte (HGK) attachment and migration. Attachment tests were performed with HGK prelabeled by tritiated ammo‐acids. Increasing concentrations of minocycline (10, 50, 100μg/ml) in the medium produced no significant modification of cell adhesion kinetics compared to control conditions, except for 100μg/ml which statistically significantly (p < 0.05) reduced the number of attached cells beyond 6 h. A 24‐h cell preincubation in 10 μg/ml of minocycline did not alter the kinetics of HGK attachment. Scanning electron microscopic observations of attached HGK showed that the presence of 10 fig/ml of minocyline in the “attachment medium” induced the production of multiple filopodial extensions. Migration tests in Boyden chambers for 40 h demonstrated that HGK preincubation for 24 h in a 10μg/ml minocycline‐HCl solution increased significantly (p<0.005) cell migation towards a gradient of fetal calf serum. The presence of 10 μg/ml of minocycline in contact with the kerationocytes in the upper compartment of the migration chambers also produced a significant (p < 0.005) result. In contrast, the presence of minocycline in the lower compartments did not produce any chemo attractive effect. Within the limits of their significance, these results suggest that, at concentrations not beyoud50μg/ml, minocycline could fasten the periodontal wound coverage by epithelial cells and allow the normal reformation of junctional epithelium.
Lectins inhibit periodontal ligament fibroblast attachment, spreading and migration on laminin substrates
Authors: Dean J. W. , Karshen B. , Briggett P.
Published: July 2006

The ways in which carbohydrate signals from the extracellular matrix influence the responses of periodontal ligament (PDL) fibroblasts are essentially unknown. The purpose of this study, using video digital image analysis, was to examine the effects of lectins on the attachment, spreading and migrational responses of rat periodontal ligament fibroblasts on the highly glycosylated glycoprotein laminin (LN) in vitro. PDL fibroblasts were isolated from rat molar teeth and grown in culture. Bound LN and control substrates (bovine serum albumin and untreated plastic) were incubated with solutions of either wheatgerm agglutinin (WGA), specific for N‐acetylglucosamine, or concanavalin A (ConA), specific for mannose, in 96‐well plates. Unbound lectin was rinsed away and 10.0 × 103 cells were seeded per well and allowed to attach for 1.5 h. Incubation of LN substrates with WGA, prior to the addition of any cells, inhibited PDL fibroblast binding more than 5‐fold. ConA, however, had no effect on cell binding but inhibited mean individual cell spreading nearly 3‐fold under similar assay conditions. The effects could be prevented by adding each lectin's respective specific sugar. The lectins had no effects on the control substrates. In a 24‐h cell migration assay WGA and ConA both significantly inhibited migration of PDL fibroblasts. It is likely that WGA inhibited cell attachment and cell migration, by binding to oligosaccharides and blocking access to adjacent polypeptide cell recognition sequences on LN. The results from the ConA experiments, where binding was allowed but spreading was severely inhibited, suggest a possible informational role for the carbohydrates present on LN.
Cost‐effective design for dental randomized clinical trials with longitudinal observations
Authors: Hefti Arthur F. , Yang Mark C.
Published: July 2006

In general, randomized clinical trials (RCT) in dentistry involve longitudinal observations. In such studies, the total cost is a function of the number of study subjects and visits, the study duration, and the type and number of examinations at each visit. In this paper, we derived the minimum cost design for longitudinal RCTs with 2 treatment arms and multiple visits. We optimized the number of subjects, visits and repeated measurements under the constraints of the requirements for statistical significance, power and minimum total study cost. A SAS macro was written and made available on the World Wide Web, so interested clinical investigators can easily find optimal designs. The application of the program is illustrated using an example.
Systemic manifestations of periodontitis in the non‐human primate
Authors: Ebersole J. L. , Cappelli D. , Mott G. , Kesavalu L. , Holt S. C. , Singer R. E.
Published: July 2006

This report describes our findings regarding the potential contribution of periodontitis to atherosclerotic processes using a nonhuman primate model. The goal of the investigations was to target general mechanisms which could describe the association of these disease processes, including: (i) systemic translocation of bacteria/products during periodontitis; (ii) alterations in systemic inflammatory biomarkers during periodontitis; and (iii) the relationship of periodontitis to serum lipids /lipoproteins. Increases in serum endotoxin (e.g. LPS) during ligature‐induced periodontitis were observed in these animals. We determined serum levels of various acute phase reactants and chemokines (e.g. CRP. α1‐antitrypsin, haptogiobin, fibrinogen, IL‐8). A number of these host factors were significantly increased during gingivitis and/or periodontitis. Finally, we observed specific changes in serum lipid levels (cholesterol, triglycerides, HDL, LDL) and lipoproteins (apoA‐I) during periodontitis, which were exacerbated by exposure of the animals to a diet with elevated fat content. Thus, we have described systemic manifestations of periodontitis that include detection of bacterial products, inflammatory biomarkers, and dyslipoproteinemia consistent with an increased atherogenic risk.
Alteration in expression of MMP‐1 and MMP‐2 but not TIMP‐1 and TIMP‐2 in hereditary gingival fibromatosis is mediated by TGF‐β1 autocrine stimulation
Authors: Coletta Ricardo D. , Almeida Oslei P. , Reynolds Mark A. , Sauk John J.
Published: July 2006

Hereditary gingival fibromatosis (HGF) is characterized by an excess accumulation of extracellular matrix (ECM) resulting in a generalized and fibrotic enlargement of the gingiva. To investigate some of the regulatory features of this condition, gingival fibroblasts from normal gingiva (NG) and HGF were examined for the expression and production of matrix metalloproteinases (MMPs) and their inhibitors, tissue matrix metalloproteinases inhibitor (TIMPs). Our results, obtained from 2 different assays, semi‐quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) and enzymography, clearly demonstrated that the expression and production of MMP‐1 and MMP‐2 was significantly lower in fibroblasts from HGF than from NG. Interestingly, TIMP‐1 and TIMP‐2 expression from NG cells was shown to be slightly higher to those from HGF. Addition of antibodies against transforming growth factor‐β 1 (TGF‐β1), which is produced in greater amounts by HGF fibroblasts, resulted in a slight increase in MMP‐1 and a decrease in MMP‐2 expression, whereas TIMP‐1 and TIMP‐2 expressions were unaffected. These patterns of expression and production suggest that enhanced TGF‐β1 production reduce the proteolytic activities of HGF fibroblasts, which favor the accumulation of ECM.
Growth and phenotype of potato plants expressing an antisense gene of P‐protein of glycine decarboxylase under control of a promoter with preference for the mesophyll
Authors: WINZER T , HEINEKE D , BAUWE H
Published: July 2006

A cDNA encoding P‐protein of glycine decarboxylase was expressed in antisense orientation in leaves of potato (Solanum tuberosum cv. Solara) under control of the promoter of a P‐protein gene of glycine decarboxylase from Flaveria pringlei. This promoter targets gene expression preferentially to the leaf mesophyll cells. In two of the transgenic lines, mitochondria oxidise glycine only with extremely low rates. Phenotypically, these transgenic lines were only marginally different from wild type plants under ambient carbon dioxide concentrations and indistinguishable from wild type plants when grown under 800 ppm carbon dioxide. When grown in ambient carbon dioxide, transgenic plants accumulated high amounts of glycine during the light period followed by nearly complete degradation in the following night.
Carbon allocation and sugar status in individual cells of barley leaves affects expression of Sucrose: Fructan 6‐Fructosyltransferase gene
Authors: KOROLEVA O A , TOMOS A D , FARRAR J F , GALLAGHER J , POLLOCK C J
Published: July 2006

Heterogeneity of function in plant tissues requires precise regulation of metabolic systems controlling resource allocation at the level of single cells. Differential distribution of metabolites between epidermis, mesophyll and parenchymatous bundle sheath (PBS) cells has already been demonstrated in barley (Hordeum vulgare L.) source leaves and partitioning of sugars in barley leaves has been proven to be highly cell‐type specific. Carbohydrate metabolism of barley leaves induced to accumulate sucrose and fructans was investigated further at the individual cell level, using single cell sampling and analysis techniques. A novel approach using reverse transcription followed by polymerase chain reaction (RT‐PCR) was used to analyse expression of the enzyme Sucrose: Fructan 6‐Fructosyltransferase (6‐SFT) in individual cells of barley leaves. Accumulation of sucrose and the synthesis of fructans were induced by reducing export of sugars from leaves (root cooling), by increasing photosynthesis (high photon fluence rates), or by supplying sugars exogenously. In all cases there was a positive qualitative correlation between the presence of 6‐SFT transcripts and accumulation of fructan and sucrose in both mesophyll and PBS cells.
Potential for manipulating carbon metabolism in wheat
Authors: SPARKS C A , CASTLEDEN C K , WEST J , HABASH D Z , MADGWICK P J , PAUL M J , NOCTOR G , HARRISON J , WU R , WILKINSON J , QUICK W P , PARRY M A J , FOYER C H , MIFLIN B J
Published: July 2006

The transformation of wheat opens up opportunities for manipulation of key steps in plant metabolic pathways. Attempts to alter the expression of sucrose phosphate synthase (SPS) and glycine decarboxylase (GDC) in wheat leaves have been made.

Using a maize SPS gene under the control of either a constitutive promoter (in p35SMSPS) or a green tissue specific promoter (in pRGMSPS), transformation of wheat (Triticum aestivum L. cv. Cadenza) led to the production of 22 independent transformed lines that contained the SPS transgene. Expression of the transgene, analysed by RT‐PCR, revealed that the transcript was present in nine of the 12 p35SMSPS plants and six of the 10 pRGMSPS plants. The maize SPS protein could not, however, be detected in any of these lines.

The expression of GDC, and in particular that of the P subunit, has been shown to be altered in plant species with the intermediate C3/C4 photosynthetic phenotype. Attempts have been made to make similar changes in the expression of GDC in wheat leaves by transforming them with full length cDNA sequences for the P subunit of GDC in the sense and antisense orientation. More than 70 transformed lines were produced. Of these, 11 contained the gene in the sense, and 31 in the antisense, orientation, as determined by PCR. Results with Tt generation plants suggested that the activity of GDC had been reduced in some lines transformed with antisense constructs. However, there was no evidence for the expression of the sense constructs. GDC mRNA could not be detected by RT‐PCR in any of the 10 lines produced in the sense transformation experiments.

Taken together, these results demonstrate the effectiveness of the technology to deliver large numbers of transgenic wheat plants. However, clearly this alone is not sufficient to guarantee the correct expression of the transgenes at sufficient levels to establish the presence of the gene product.
The role of cytosolic glutamine synthetase in wheat
Authors: HABASH D Z , MASSIAH A J , RONG H L , WALLSGROVE R M , LEIGH R A
Published: July 2006

The role of glutamine synthetase (GS; EC 6.3.1.2) was studied in wheat. GS isoforms were separated by HPLC and the two major leaf isoforms (cytosolic GS1 and chloroplastic GS2) were found to change in content and activity throughout plant development. GS2 dominated activity in green, rapidly photosynthesising leaves compared to GS1 which was a minor component. GS2 remained the main isoform in flag leaves at the early stages of grain filling but GS1 activity increased as the leaves aged. During senescence, there was a decrease in total GS activity which resulted largely from the loss of GS2 and thus GS 1 became a greater contributor to total GS activity. The changes in the activities of the GS isoforms were mirrored by the changes in GS proteins measured by western blotting. The changes in GS during plant development reflect major transitions in metabolism from a photosynthetic leaf (high GS2 activity) towards a senescencing leaf (relatively high GS1 activity). It is likely that, during leaf maturation and subsequently senescence, GS1 is central for the efficient reassimilation of ammonium released from catabolic reactions when photosynthesis has declined and remobilisation of nitrogen is occurring. Preliminary analysis of transgenic wheat lines with increased GS1 activity in leaves showed that they develop an enhanced capacity to accumulate nitrogen in the plant, mainly in the grain, and this is accompanied by increases in root and grain dry matter. The possibility that the manipulation of GS may provide a means of enhancing nitrogen use in wheat is discussed.
Variation in the harvest index of tropical maize: evaluation of recent evidence from Mexico and Malawi
Authors: HAY RKM , GILBERT RA
Published: July 2006

In temperate zones, the potential grain yield of wheat has increased during the twentieth century owing to progressive increases in the harvest index of new varieties, which are principally associated with reduction in plant stature. Crop biomass has not increased substantially. In contrast, the potential grain yield of maize in the USA has increased owing to progressive increases in biomass, principally associated with selection for grain yield at higher population density. Harvest index was already around 0.5 for recommended varieties in 1930, and has not increased significantly since. However, for both crops, the harvest index of a given variety has proved to be a highly‐heritable character, except under severe stress.

Less is known about the physiology of tropical maize. This paper reviews evidence from Mexico and Malawi that tropical maize can respond to selection for reduced stature following the same pattern as temperate wheat, but, under other circumstances, the magnitude of harvest index is not highly heritable, varying inconsistently with season, management and environment. It is proposed that these differences arise out of the unique vulnerability of the grain‐setting process around flowering. The plasticity of harvest index under long, favourable conditions, however, remains to be explained, although it is probably also related to the events around grain setting. Nevertheless, to the subsistence farmer, higher harvest index may not be a high priority in crop improvement, because of the need for large quantities of high‐quality stover.
The rate of transport through a phosphate translocator affects delayed luminescence induction: an experiment and a theoretical model
Authors: KHUZNETSOVA S , BOGRACHEVA T , HEDLEY C , TULESHOVA A , KUKUSHKIN A
Published: July 2006

Delayed luminescence (DL) induction curves were studied in leaves from a mutant pea line containing mutations at both the r and rb loci, compared with leaves from wild type plants. Genes at the r and rb loci encode starch branching enzyme and ADP ‐ glucose pyrophosphorylase, respectively. The presence of mutations at both loci, previously known to reduce the starch content in the dry mature seed by 75%, have been shown to lower the starch level in leaves by at least 20%. During induction, the half‐time for the DL intensity decrease from maximum to steady state in the mutant was 1.5 ± 0.2 times longer than for the wild type. It is proposed that the prolongation of the induction period in leaves from the mutant plants is caused by a lack of inorganic phosphate (Pi) restricting the rate of ATP synthesis at the beginning of induction. The reduced Pi would be compensated by triose flow from the chloroplast, via the triose phosphate translocator, being exchanged for Pi from the cytosol. Analysis of our theoretical photosynthesis model confirmed that a decrease in the rate of Pi released from the Calvin cycle could lead to a prolongation of the induction period.
Using plant analysis to predict yield losses caused by sulphur deficiency
Authors: BLAKE‐KALFF MECHTELD M A , ZHAO FANG‐JIE , HAWKESFORD MALCOLM J , McGRATH STEVE P
Published: July 2006

Yield losses in agricultural crops as a result of sulphur deficiency are increasing in the UK, because of the decrease in sulphur dioxide emissions and changes in fertiliser practices. Therefore, there is a need for a reliable and practical diagnostic indicator to predict early in the growing season whether it is necessary to apply S fertiliser, but also to avoid the application of fertiliser when not necessary. A successful diagnostic indicator should be reliable and stable throughout plant development, but also easily measured with great accuracy and as little effort as possible. In this paper the difficulties and problems with currently used diagnostic tests for S deficiency, such as total S, sulphate or the N:S ratio, will be discussed. A more reliable and practical indicator of S deficiency is the malate: sulphate peak area ratio which is at present being developed for use by commercial laboratories and their customers.
The impact of the aphids Tuberolachnus salignus and Pterocomma salicis on willow trees
Authors: COLLINS C MATILDA , ROSADO RUI G , LEATHER SIMON R
Published: July 2006

The effect of two species of stem‐feeding aphid on the yield, phenology and water‐use of soil‐grown and hydroponic‐cultured willow were investigated. The effects of Pterocomma salicis were less marked than those of Tuberolachnus salignus. The latter reduced not only the above and below‐ground growth of trees made during and subsequent to infestation, but also altered the mass of previously developed woody tissue. The negative effects of T. salignus on the shoots and roots of established and establishing trees were drastic and were both quantitative and qualitative. They were also observed to reduce the survival of infested trees. P. salicis had negative effects on the growth of roots and shoots during infestation, but the influence of this species did not persist nor did it influence previous growth.
The roles of ascospores and conidia of Pyrenopeziza brassicae in light leaf spot epidemics on winter oilseed rape (Brassica napus) in the UK
Authors: GILLES T , FITT B D L , McCARTNEY H A , PAPASTAMATI K , STEED J M
Published: July 2006

Ascospores of Pyrenopeziza brassicae were produced in apothecia (cup‐shaped ascomata) on oilseed rape debris. The conidia, which were morphologically identical to the ascospores, were produced in acervular conidiomata was greater than for lesions caused by ascospores. In June 2000, on the ground under a crop with light on the surface of living oilseed rape tissues. Ascospores were more infective than conidia on oilseed rape leaves. The proportion of lesions caused by conidia located on leaf veins leaf spot, numbers of petioles with apothecia decreased with increasing distance into the crop from the edge of pathways. Air‐borne ascospores of P. brassicae were first collected above debris of oilseed rape affected with light leaf spot on 5 October 1998 and 18 September 1999,12 or 23 days, respectively, after the debris had been exposed outdoors. P. brassicae conidia were first observed on leaves of winter oilseed rape on 6 January 1999 and 15 February 2000, respectively, after plots had been inoculated with debris in November 1998 and October 1999. In 1991/92, numbers of ascospores above a naturally infected crop were small from January to April and increased in June and July. P. brassicae conidia were first observed in February and the percentage plants with leaves, stems or pods with light leaf spot increased greatly in May and June. In 1992/93, in a crop inoculated with debris, numbers of airborne ascospores were small from October to January and increased from April to June. P. brassicae conidia were first observed on leaves in late November and light leaf spot was seen on stems and pods in March and June 1993, respectively.
A new disease in Tabernaemontana associated with Tobacco mild green mosaic virus
Authors: COHEN J , ROSNER A , KAGAN S , LAMPEL M , MASLENIN L , ZEIDAN M , GERA A
Published: July 2006

Conspicuous viral symptoms were seen on Tabernaemontana divaricata, a member of the family Apocynaceae, grown in a commercial nursery, in Israel. The symptoms varied widely and included chlorotic ringspots and banding, oak‐leaf patterns and mosaic. At the end of the winter, large yellow spots, which later became necrotic, appeared on fully expanded leaves. The necrotic zones later fell out, leaving “shot holes”. Preliminary analysis suggested that the disease was associated with a tobamovirus. Particles typical of a tobamovirus were observed by electron microscopy only in samples taken from symptomatic leaves. Apartial segment of the 5′‐terminus of the viral RNA, which comprised of 533 bp was cloned and sequenced. Comparison of the predicted amino acid sequence with those of other tobamoviruses revealed 94% identity with Tobacco mild green mosaic virus (TMGMV) genome. Primers specific to the coat protein (CP) gene of TMGMV used in a reverse transcription‐polymerase chain reaction assay (RT‐PCR) gave an expected amplification product of 455 bp. The amino acid composition of the cloned CP gene, which shows a complete identity to that of TMGMV, confirmed the identity of TMGMV infecting Tabernaemontana. Polyclonal antibodies prepared against the virus and used in double antibody sandwich enzyme‐linked immunosorbent assay (DAS‐ELISA) enabled specific detection of the virus in crude sap extracted from T. divaricata and mechanically inoculated indicator plants. This is the first report of TMGMV infection in Tabernaemontana and the first incidence of the virus in Israel.
Virus infection stimulates phyto‐oestrogen production in pasture legume plants growing in grazed swards
Authors: JONES R A C , FERRIS D G
Published: July 2006

Four field experiments were sown with AMV‐infected or healthy seed of burr medic (Medicago polymorpha) and grazed by sheep; two were sown with cv. Circle Valley and two with cv. Santiago. Seed‐infected plants acted as primary sources for virus spread by naturally occurring aphids. Insecticides and admixture with annual ryegrass (Lolium rigidum), a non‐host of AMV, suppressed virus spread to different extents in the plots sown with infected seed. Effects of the different amounts of virus spread obtained on overall concentration of the oestrogenic compound coumestrol (dihydroxycoumestan) in dry stems and pods, and on seed production were measured in the medic. With cv. Santiago, stem and pod coumestrol concentration values for plots sown with healthy seed were significantly smaller than those for all plots sown with infected seed regardless of whether they were sprayed. With cv. Circle Valley, the coumestrol values for stems from plots sown with healthy seed were significantly smaller than those for unsprayed plots sown with infected seed but not than those for sprayed plots or ones with grass admixtures, and there were no significant differences with pods. There was always a significant positive relationship between concentration of coumestrol in medic stems and percentage AMV infection of swards; this was also so with pods in two experiments. A linear model best fitted this relationship with cv. Circle Valley but a logarithmic model did so with cv Santiago. In glasshouse grown plants, the coumestrol content of dried medic shoots was increased 11 (cv. Circle Valley) and five (cv. Santiago) times by AMV infection. AMV increased mean coumestrol concentrations up to 256 ppm (field) and 237 ppm (glasshouse) in stems and 223 ppm in pods (field). Sowing healthy seed in new pasture swards was an effective strategy for minimising coumestrol accumulation in burr medic swards. Two, but not single, applications of a newer generation pyrethroid insecticide to swards in which AMV was spreading significantly diminished coumestrol accumulation but applying organophosphorus insecticide twice and carbamate insecticide repeatedly did not. Medic seed yields and individual seed weights were sometimes significantly increased by the treatments, suppression of AMV spread by regular carbamate sprays being sufficient to increase seed yield by 55%.
Molecular characterisation of Onion yellow dwarf virus (OYDV) infecting garlic (Allium sativum L.) in Israel: Thermotherapy inhibits virus elimination by meristem tip culture
Authors: SHIBOLETH Y M , GAL‐ON A , KOCH M , RABINOWITCH H D , SALOMON R
Published: July 2006

Garlic (cv. Shani) was tested using single step RT‐PCR and digoxygenin (DIG) labelled dot‐blot for a number of viruses. Following sequence analysis it was shown that at least three different polymorphs of the potyvirus Onion yellow dwarf virus (OYDV) infect the same plant simultaneously, together with the potyvirus Leek yellow stripe virus (LYSV), the carlavirus Garlic common latent virus (GCLV) and a multitude of allexiviruses (Shallot virus X (ShVX) related viruses]. Several garlic plants free of all the viruses tested were obtained through meristem‐tip culture. Plants infected with single viruses or with different combinations of viruses were similarly obtained. Meristem‐tip culture was confirmed as a satisfactory method of virus eradication, while thermotherapy treatment given to mother plantlets before meristem excision was found to specifically antagonise OYDV eradication. This work uses molecular methods for the first time to examine the effectiveness of meristem‐tip culture for the eradication of multiple viruses from garlic.
Modelling crop physiology for integrated decision making
Authors: DAY W
Published: July 2006

Crop modelling has had a mixed press over the years, driven as much by the community's expectations as by the targets identified by modellers. This short review gives a personal perspective on the scope and value of models of crop processes and performance, in the context of the increasing demand to make predictions about the best course of action for farmers. The goal for these predictions can range from the best rate or timing for a pesticide spray to the likely pressure on the farming community if predicted levels of climate change are realised. The primary conclusion is that a clear statement of objectives is the most important precursor to the use of models of crop processes or systems.
Effects of hot water treatments and storage temperatures on the ripening and the use of electrical impedance as an index for assessing post‐harvest changes in mango fruits
Authors: NYANJAGE M O , WAINWRIGHT H , BISHOP C F H
Published: July 2006

The effects of hot water treatment and storage temperature (4°C, 13°C or 22°C) on the quality and impedance of outer and inner mesocarp of mango were assessed in two experiments during storage, impedance being a potential non‐destructive measure of tissue damage following heat treatment. Fruits were subjected to equivalent heat units at 36.5°C for 60 min plus 46.5°C for 43 min or 46.5°C for 90 min by hot water treatments (hwt) on the assumption of cumulative heat effects and a base temperature of 12–13°C. Fruit reflectance decreased whereas chroma and hue angle increased over storage time and also with increase in storage temperature. The yellow colour increased with a rise in storage temperature in hot water treated mangoes. Soluble solids content of mangoes held at 22°C was highest at 5 days of storage but decreased subsequently over storage time. Impedance of all fruits decreased with increase in frequency, storage temperature and time in store. The impedance of hwt mangoes was lower than that of non‐hwt fruits 8 h after immersion, but recovered almost to control levels on day 5 at 4°C or 13°C, but decreased gradually after 5 days at 13°C. Impedance of all mangoes stored at 22°C decreased continuously during storage. Impedance was higher in the inner mesocarp than outer pulp. Impedance of hwt fruits was poorly correlated with soluble solid content and chroma but well correlated with reflectance of fruit pulp at 22°C. Changes in impedance of mangoes are discussed in relation to physiological and biochemical changes that occur during heat treatment and storage.
Disease spread patterns of Banana streak virus in farmers, fields in Uganda
Authors: KUBIRIBA J , LEGG J P , TUSHEMEREIRWE W , ADIPALA E
Published: July 2006

Three surveys were conducted to establish the disease spread patterns of Banana streak virus (BSV) in farmers, fields in Uganda. Transects were traced both across the fields and from infection foci within a field. BSV incidence in adjacent quadrats was also determined to quantify statistically the spatial relationships of infected plants in the fields. Severity assessment along transects across fields revealed clusters of plants with moderate to high severity and clusters of plants with no BSV or low severity. Symptom severity decreased away from foci of infection (b=−0.014; P=0.0081). Observed frequency of infected quadrat counts differed from corresponding expected frequency of infected quadrat counts (Poisson, s distribution, x2; P<0.01). BSV– infected plants, therefore, were aggregated in well‐established fields. Aggregation of infected plants in farmers, fields and the decrease of severity away from infection foci suggest the likely involvement of a slow moving vector in BSV transmission.
Vector transmission of Banana streak virus in the screenhouse in Uganda
Authors: KUBIRIBA J , LEGG J P , TUSHEMEREIRWE W , ADIPALA E
Published: July 2006

Although mealybug transmission of Banana streak virus.(BSV) by Planococcus citri and Saccharicoccus sacchar has been demonstrated elsewhere, these mealybugs have not been identified on bananas in Uganda and their role and that of other agents in BSV transmission is not well documented. Insect samples were collected from banana farms in sites with low, moderate and high BSV infections in Uganda. Subsequently, live mealybugs and aphids were again collected and used in acquisition, retention and transmission tests, and BSV diagnosed using TAS‐ELISA. Dysmicoccus brevipes (pineapple mealybug), S. sacchari (sugarcane mealybug) and Pentalonia nigronervosa (banana aphid) were the most abundant insect species from banana fields sampled. Abundance of D. brevipes was positively and significantly correlated with BSV incidence unlike that of. P. nigronervosa. Transmission studies in the screenhouse showed that mealybugs acquired BSV one day after feeding on virus sources and approached optimum acquisition after the third day. Pineapple and sugarcane mealybugs retained BSV up to 5 days from the day of transfer from the virus source. BSV was first detected in the recipient banana plants 4 wk after transmission using pineapple mealybug and 6 wk after inoculation using sugarcane mealybug. Under screenhouse conditions, both mealybugs therefore appear to transmit BSV semipersistently.
The effect of Banana streak virus on the growth and yield of dessert bananas in tropical Australia
Authors: DANIELLS J W , GEERING A D W , BRYDE N J , THOMAS J E
Published: July 2006

We have examined the effect of a strain of Banana streak virus (BSV‐Cav) on the growth and yield of dessert bananas (Musa AAA group, Cavendish subgroup cv. Williams) in north Queensland, Australia. Healthy and infected plants were compared in a replicated field experiment over plant and first ratoon crops. In both crops, symptom expression followed a similar pattern, increasing to a maximum near the estimated time of bunch initiation, then decreasing in the period prior to bunch emergence. There was no evidence of plant‐to‐plant spread of virus, but the rate of transmission through suckers was 100%. In the plant crop, the mean bunch weights of healthy and infected plants were not significantly different. However, BSV‐Cav infection resulted in an 18 day delay in harvest, causing a 6% reduction in yield per annum. In the ratoon crop, the mean bunch weight of infected plants was 7% less than that of healthy plants, and the interval between the harvest of plant and ratoon crops was delayed by 9 days, resulting in a 11% reduction in yield per annum. Also, the mean length of fruit from infected plants was 5% less than that of healthy plants, resulting in a smaller percentage of fruit in the extra large size category. We conclude that in horticulturally favourable conditions typical of the tropical Australian banana industry, the effects of BSV‐Cav infection on the growth and yield of Cavendish bananas are small.
Assessment of variation in Aceria cajani using analysis of rDNA ITS regions and scanning electron microscopy: implications for the variability observed in host plant resistance to pigeonpea sterility mosaic disease
Authors: KUMAR P LAVA , FENTON B , DUNCAN G H , JONES A T , SREENIVASULU P , REDDY D V R
Published: July 2006

Aceria cajani on pigeonpea (Cajanus cajan) is the vector of the agent of pigeonpea sterility mosaic disease (PSMD), a very damaging virus‐like disease in the Indian subcontinent. PCR was used to amplify A. cajani nuclear ribosomal DNA (rDNA) internal transcribed spacers (ITS) and associated rDNA genes. They were assessed for variation in this genome region by nucleotide sequencing and RFLP. A. cajani‐specific rDNA primers are described. Several A. cajani populations were collected from pigeonpea plants from various PSMD endemic locations in India, Nepal and Myanmar. No significant variation was identified in rDNA regions, or in morphological features. These results suggest strongly that A. cajani on pigeonpea across the Indian subcontinent constitutes one species and that no other Aceria species and probably no A. cajani biotypes that differ in vectoring ability are involved in the transmission of the agent of PSMD. The implications of these findings for the variability observed in PSMD‐resistant pigeonpea genotypes across various locations in India are discussed.
The diversity of earthworms in 200 Scottish fields and the possible effect of New Zealand land flatworms (Arthurdendyus triangulatus) on earthworm populations
Authors: JONES H D , SANTORO GIULIO , BOAG BRIAN , NEILSON ROY
Published: July 2006

Earthworm populations from 200 fields (132 pasture and 68 arable) in Scotland are compared. Earthworms populations from two pasture fields at a Scottish farm infested with the New Zealand terrestrial planarian,Arthurdendyus triangulates(a predator of earthworms), are compared with a subset of these 200 fields (none of which had planarians at the time of the survey). A variety of univariate and multivariate methods are used for comparison. Results from the 200 fields show that the number of individuals, number of species, richness and diversity decline eastwards and northwards across Scotland. There is an overall difference between pasture and arable fields at the same farm, with fewer anecic earthworms (Aporrectodea longa and Lumbricus terrestris), but moreAporrectodea rosea, in arable fields. Conversely, species richness and cumulative species diversity is greater in arable fields, and sample similarity is less. The planarian‐infested fields show differences from the subset of western Scottish pasture fields and from each other. Both have fewerAporrectodea caliginosa(and endogeic total) andA. longa(and anecic total) than the western pasture fields. One field has fewerL. terrestrisand fewer earthworms in total. Univariate factors show no significant differences between the infested fields and similar non‐infested fields, but multivariate analysis suggests differences. Waterlogging and recent growth of rushes in the infested fields are discussed in relation to the reduced population of earthworms and to rainfall.
Effects of carbonyl sulfide, methyl iodide, and sulfuryl fluoride on fruit phytotoxicity and insect mortality
Authors: AUNG L H , LEESCH J G , JENNER J F , GRAFTON‐CARDWELL E E
Published: July 2006

Three potential chemical fumigants: carbonyl sulfide (COS), methyl iodide (MI) and sulfuryl fluoride (SF) were tested at selected dosages on lemons against California red scale (Aonidiella aurantii) and MI and COS were tested on nectarines against codling moth (Cydia pomonella). In nectarines, COS was tested at 0, 20, 40, 60 and 80 mg litre−1, MI at 0, 10, 15, 20 and 25 mg litre−1. Both fumigants intensified nectarine peel color, delayed fruit softening, but did not alter overall fruit quality. COS at 80 mg litre−1 resulted in 87% codling moth mortality, but the fumigant dosage was insufficient to reach the desired probits 9 level (99.9968%). MI gave 100% codling moth mortality at 25 mg litre−1. Lemons were treated with MI at 0,10,20,40,60 mg litre−1, SF at 0,10,20,40, 80 mg litre−1 and COS at 0,20,40, 60 and 80 mg litre−1. MI gave 100% red scale mortality at ≥40 mg litre−1 but caused significant fruit injury. Conditioning lemons at 15°C for 3 days before MI fumigation lessened lemon phytotoxicity. Forced aeration at 3.5 standard litres per minute of lemons for 24 h following MI fumigation at 20 mg litre−1 significantly reduced phytotoxicity compared to 2 h postfumigation aeration after MI treatment. SF at ≥40 mg litre−1 gave 100% red scale mortality but resulted in commodity phytotoxicity. Lemons treated with the highest selected dose of 80 mg litre−1 COS gave only 87% kill of red scale, but failed to reach the desired probit 9 level.
A mixture of begomoviruses in leaf curl‐affected tobacco in Karnataka, South India
Authors: PAXIMADIS M , MUNIYAPPA V , REY M E C
Published: July 2006

Tobacco leaf curl is widespread in several states in India including Andhra Pradesh, Gujarat, Karnataka, Bihar and West Bengal. Tobacco leaf curl virus (TbLCV) isolates collected from five different parts of India induced four distinct symptom phenotypes (group I, II, III & IV) on tobacco cultivars Samsun and Anand 119 (Valand & Muniyappa, 1992). PCR was performed on DNA extracted from group I and IV leaf curl‐affected tobacco from Karnataka, India using degenerate begomovirus‐specific primers. Subsequent cloning and sequencing of PCR products revealed preliminary evidence for the presence of at least three begomoviruses in the affected material following alignment of a 333 bp region of the coat protein gene (CP). The complete CP and common region (CR) of two putative begomoviruses, Tobacco leaf curl virus‐Karnataka1 (TbLCV‐Kar1) and Tobacco leaf curl virus‐Karnataka2 (TbLCV‐Kar2), were sequenced using PCR clones obtained with designed sequence‐specific primers. Phylogenetic analysis of the CP and CR of TbLCV‐Kar1 and TbLCV‐Kar2 placed them in the Asian Old World begomovirus cluster. The two viruses differed from each other significantly in both the CP gene and the CR (< 90% nucleotide sequence identity). This difference, in conjunction with distinct iterative sequences strongly suggests that these begomoviruses are distinct from one another. Group I and IV tobacco were also found to harbour a possible third begomovirus following the 333 bp CP alignment. Comparison of TbLCV‐Kar1 and TbLCV‐Kar2 with other geminiviruses, showed that both sequences shared high nucleotide sequence identity (> 90%) with other begomoviruses in either the CP or CR, thereby suggesting these viruses to be possible strains of other reported begomoviruses. Combined comparison of the CP and CR sequences however, suggests that the two viruses are not strains of other reported begomoviruses, but may be distinct begomoviruses that could have arisen through recombination events during mixed infections.

Phylogenetic comparison demonstrated no significant homology between the Indian tobacco begomoviruses and a tobacco‐infecting begomovirus from Zimbabwe, again showing that as with other geminiviruses, there is a geographic basis for phylogenetic relationships rather than an affiliation with tobacco as a host.
Resource provision for farmland gamebirds: the value of beetle banks
Authors: THOMAS S R , GOULSON D , HOLLAND J M
Published: July 2006

Severe declines have occurred in the populations of wild game birds in Britain. This has been attributed to agricultural intensification, leading to the loss of invertebrates vital within chick diets, fewer feeding resources for adults, and inadequate provision of nesting and brood‐rearing habitat. This paper explores the potential value of simple sown grass strips – beetle banks – in providing these resources, and compares results with functionally similar conventional field margins. The data indicate that beetle banks can contribute useful, albeit lower, densities of chick‐food than conventional margins. These resources are more abundant later in the season, which may have implications for early hatched chicks. Beetle banks provide considerable quantities of nesting cover for adults, although sheltering conditions may never be as satisfactory as in well managed hedgerows. Given the ease and low cost of establishment of beetle banks, we suggest that they may be valuable components within a range of game management techniques on the farm, as a ‘spin‐off’ to their primary role as overwintering habitat for polyphagous predators. They may be important particularly where resources for game birds are impoverished, but clearly cannot substitute for suitably managed field margins.
Presence of Neotyphodium‐like endophytes in European grasses
Authors: LEYRONAS C , RAYNAL G
Published: July 2006

In order to improve knowledge of Neotyphodium‐likc fungi in European grasses, microscopic detection of endophytic mycelium was achieved in living grasses and in seeds. Samples of grasses were gathered near permanent pastures or along paths in France (93 samples, 13 genera, 22 species). Typical convoluted mycelium was found inside leaf sheaths of four genera, especially in Festuca and Lolium spp. The results suggest that endophytes were present most often in the southern regions where plants may suffer from summer drought. Endophytes were looked for in 489 seed samples (63 genera, 237 species) received from 24 European botanical gardens. Neotyphodium was found in seeds of only six genera (22 species), especially in Festuca (15 species) and Lolium (three species). No endophytic mycelium was found in the other 215 species, although other work had demonstrated the presence of the fungus in 39 of the species analysed. Neotyphodium‐likc mycelium was detected for the first time in Festuca juncifolia, F. trachyphylla, F. vaginata, F. pseudodalmatica, F. rupicaprina, F. arenaria, Vulpia ciliata and Micropyrum tenellum. Further studies are needed for the correct identification of the Neotyphodium species observed.
Canopy height and seed yield in winter linseed (Linum usitatissimum) can be influenced by proximity to pink canes
Authors: WILTSHIRE J J J , ANDERSEN M , ATHERTON J G , WRIGHT C J
Published: July 2006

Changes to growth and development in a winter linseed crop were observed adjacent to pink canes used as markers in 1997. Notably, canopy height was increased in plants positioned up to 40 cm from the pink canes. In 1998 these effects were confirmed and further characterised in a replicated experiment: extension growth occurred approximately one week earlier and canopy height was increased by 14.5 cm in plants adjacent to pink canes. The number of seed capsules was 953 m−2 in control plots and 2567 m−2 in plots with pink canes. Seed yield, calculated from a 0.25 m2 quadrat, was 12.4 g m2 in control plots and 56.1 g m−2 in plots with pink canes. The R:FR (red:far red) ratio of light reflected from canes was approximately 1.7 compared with approximate R:FR ratios of 1.4 in incident daylight and 0.2 in light reflected from a linseed canopy (assessed using a spectral analysis system). Possible mechanisms to explain the changes in crop performance are discussed.
Ingestion, transmission, and persistence of Chino del tomate virus (CdTV), a New World begomovirus, by Old and New World biotypes of the whitefly vector Bemisia tabaci
Authors: IDRIS A M , SMITH S E , BROWN J K
Published: July 2006

Two whitefly biotypes of Bemisia tabaci, from either the Eastern or Western Hemisphere, respectively, were compared with respect to their competency to ingest and their efficiency to transmit the New World begomovirus, Chino del tomate virus (CdTV). The AZ A biotype of B.tabaci originates from the arid southwestern USA and northwestern Mexico, while the B biotype has an origin in the Middle East or Northern Africa. The ability of these two vector biotypes to ingest and subsequently to transmit CdTV were evaluated for an acquisition‐access period (AAP) that ranged from 0 to 72 h, followed by a 48 h inoculation‐access period (IAP). Individual adult whiteflies were monitored for CdTV ingestion using polymerase chain reaction (PCR) to detect the viral coat protein gene (AV1 ORF), and transmission efficiency (frequency) was determined by allowing potentially viruliferous whiteflies access to tomato seedlings following each experimental AAP. PCR results for individual adult whiteflies indicated that CdTV was ingested from infected tomato plants by both biotypes 93% of the time. Transmission frequencies by both vector biotypes increased with longer AAPs. However, the AZ A biotype transmitted CdTV 50% of the time, compared to only 27% for the B biotype. Evidence that virus was ingested with equal competency by the A and B biotypes confirmed that both vectors were capable of ingesting CdTV from tomato at the same frequency, even when the AAP was 0.5 h. Consequently, either the acquisition and/or transmission stages of the pathway, rather than ingestion competency, were responsible for differences in vector‐mediated transmissibility. Detection frequency of CdTV, after 48 h AAP, by PCR in single females of AZ B biotype was significantly higher than males.