bluuebunny/crossref_metadata_2025_split huggingface dataset:
Can gene delivery close the door to HIV‐1 entry after escape?
Authors: Swan C.H. , Torbett B.E. 
Published: July 2006

AbstractBackground  Research efforts to prevent viral entry by developing small molecule inhibitors against HIV‐1 chemokine coreceptors have yielded promising clinical results. However, resistance to some chemokine receptor inhibitors has been recently documented, and therefore, alternative methods of HIV‐1 coreceptor disruption are needed.Conclusion  We will describe current HIV‐1 vector‐delivered genetic disruption mechanisms that target HIV‐1 chemokine coreceptors, such as RNA interference, ribozymes, zinc fingers, intrakines, and intrabodies, and frame the use of these gene delivery chemokine receptor disruption mechanisms in the context of current small molecule blocker/antagonists of CCR5 and CXCR4. In addition, we will discuss the importance of evaluating HIV‐1 vector‐delivered viral entry prevention mechanisms in the rhesus macaque SIV non‐human primate model in regard to pathogenesis and therapeutic efficacy.
Measuring and modelling the effects of inoculation date and aphid flights on the secondary spread of Beet mosaic virus in sugar beet
Authors: DUSI A N , PETERS D , VAN DER WERF W 
Published: July 2006

SummaryThe effect of the inoculation date on the spread of Beet mosaic virus (BtMV) in sugar beet field plots was studied. Two plants in the centre of each plot were inoculated with BtMV using Myzus persicae. The spread of the infection around these sources was monitored by inspecting the plants on two diagonal transects through the centre of the plot. Early inoculations resulted in a greater spread than late inoculations, but any inoculation before the onset of the aphid migration resulted in a similar‐sized spread. The spread was concentrated in patches around the inoculated plants, and its rate was explained by vector pressure, as shown by regression analysis and a mechanistic simulation model. This vector pressure was quantified using data obtained by catching aphids in a green water trap in the crop, catching aphids in a 12 m high suction trap at a distant location, and infection of bait plants from adjacent virus source plants. The daily total aphid catches obtained by a suction trap provided the best statistical explanation for the spread of this virus. The parameter r, describing the relationship between vector pressure and the rate of disease progress, was remarkably robust. This parameter varied less than 10% between treatments (infection date) within a single experiment, and less than a factor two between four experiments performed at different sites in two years. The robustness of this parameter suggests that the spread of a potyvirus may be predicted on the basis of the initial infection date and vector abundance.
Tolerance to reniform nematode (Rotylenchulus reniformis) race A in pigeonpea (Cajanus cajan) genotypes
Authors: SHARMA S B , JAIN K C , LINGARAJU S 
Published: July 2006

SummaryThe reniform nematode (Rotylenchulus reniformis) is an important pathogen of pigeonpea (Cajanus cajan). Forty‐six medium maturity (mature in 151–200 days at Patancheru, India) pigeonpea genotypes were evaluated for resistance and tolerance to the reniform nematode in greenhouse and field tests, over the period 1990–97. Each genotype was screened for number of nematode egg masses on a 1 (no egg mass = highly resistant) to 9 (> 50 egg masses = highly susceptible) scale. Plant biomass production in carbofurantreated plots was compared with that in non‐treated plots in a field naturally infested with R. reniformis. Pigeonpea genotypes C 11, ICPL 87119 and ICPL 270 were used as nematode susceptible checks. Genotypes with good plant growth, both in nematode‐free and nematode‐infested plots, were identified as tolerant and evaluated for plant growth and yield for at least three years. All the tested genotypes were susceptible (7 and 9 egg mass score). Single‐plant‐selections, based on plant vigour and yield, were made from genotypes showing tolerance to nematode infection. The level of tolerance was enhanced by plant‐to‐progeny row selection for plant vigour and seed yield in a nematode‐sick field for at least three years. The most promising nematode tolerant genotypes produced significantly greater yield and biomass than the locally grown pigeonpea cultivars in fields naturally infested with R. reniformis at two locations. Pigeonpea landraces are considered to be the most likely sources of tolerance to the nematode. These reniform nematode tolerant lines represent new germplasm and they are available in the genebank of pigeonpea at ICRISAT bearing accession numbers ICP 16329, ICP 16330, ICP 16331, ICP 16332, and ICP 16333.
Ovule differences between single‐kernelled and double‐kernelled fruits in almond (Prunus dulcis)
Authors: EGEA J , BURGOS L 
Published: July 2006

SummaryIn order to detect differences between almond cultivars that commonly produce one or two seeds, we compared ovule sizes and developmental stages at anthesis and three days after anthesis. The results showed that the presence of only small differences in size between primary and secondary ovules during flowering seemed to be a necessary but not sufficient condition for the production of double‐kernelled fruits. In contrast, differences in the developmental stage of both ovules did not prevent the production of double kernels. Large differences in ovule size at anthesis or in the following days resulted in fruits with single seeds. The behaviour of the secondary ovules in cultivars producing fruit with single seeds was very different, even in closely related cultivars. The degeneration of the secondary ovule seems to be genetically programmed and follows a genotype‐dependent pattern.
Occurrence of Peronospora sparsa (P. rubi) on cultivated and wild Rubus species in Finland and Sweden
Authors: KOPONEN H , HELLQVIST S , LINDQVIST‐KREUZE H , BÅNG U , VALKONEN J P T 
Published: July 2006

SummaryAn outbreak of a dryberry disease caused by Peronospora sparsa (syn. P. rubi) occurred in plantations of arctic bramble (Rubus arcticus subsp. arcticus) in Finland in the middle of 1990s. The disease persists and is most severe in cool and rainy summers. The disease has not been encountered in northern Sweden where cultivars (R. arcticus nothosubsp. stellarcticus) different from those in Finland are used. The occurrence of P. sparsa in wild Rubus spp. is virtually unknown in both areas and it is not known whether they constitute a potential infection source. Therefore, the aim of this study was to investigate the occurrence of P. sparsa on wild Rubus spp. growing in the vicinity of cultivations of arctic bramble. Symptomatic plants were sampled in 1997–1999. P. sparsa was detected using a light microscope, preceded by incubation of the sample in vitro if necessary, and by a polymerase chain reaction (PCR) based method. Plants of cultivated R. arcticus subsp. arcticus were commonly infected by P. sparsa in Finland. P. sparsa was also found on the cultivated R. arcticus nothosubsp. stellarcticus in Finland and Sweden. However, the infected plants of the cultivars of nothosubsp. stellarcticus seemed to be much less damaged than the cultivars of subsp. arcticus. Plants infected with P. sparsa were found in the populations of wild R. arcticus subsp. arcticus in both countries, and in cloudberry (R. chamaemorus) in natural habitats in Finland. In addition, P. sparsa was detected on specimens of R. arcticus subsp. arcticus (collected in 1966–1985) and R. chamaemorus (collected in 1899–1981) in Finnish herbaria. The samples of R. idaeus and R. saxatilis collected from the field in this study or investigated in the herbaria were not infected with P. sparsa. These data show that P. sparsa has not recently invaded Finland but has become an economically significant pathogen during the rapid expansion of cultivation of the apparently sensitive clones of arctic bramble.
Tomato spotted wilt virus (TSWV) in Greece: its incidence following the expansion of Frankliniella occidentalis, and characterisation of isolates collected from various hosts
Authors: CHATZIVASSILIOU E K , WEEKES R , MORRIS J , WOOD K R , BARKER I , KATIS N I 
Published: July 2006

SummaryLeaf samples were collected from plants with tospovirus‐like symptoms from various hosts in different regions of Greece where Thrips tabaci, Frankliniella occidentalis or both vectors occur. The viruses infecting these plants were identified with polyclonal antibodies raised against the N proteins of Tomato spotted wilt virus (TSWV) and Impatiens necrotic spot virus (INSV) by ELISA. All samples tested positive for TSWV, but not for INSV. ELISA of thirty three isolates, using monoclonal antibodies against the N protein of TSWV, revealed the existence of five epitopes on the N protein. RT‐PCR tests on a few randomly‐selected isolates, using a pair of universal primers, a pair of primers specific for the L gene and a pair of primers specific for the N gene, as well as sequence analysis of a part of the S gene of one isolate, confirmed the authenticity of the virus isolated as TSWV. Host range studies showed differences in susceptibility, especially among species belonging to the Leguminosae and Cucurbitaceae. The species Beloporone guttata and Coleus sp. are reported for the first time as hosts of the virus, whereas Solanum melongena, Celosia cristata, Dianthus chinensis, Stephanotis floribunda and Catharanthus roseus were identified as new hosts of TSWV in Greece.
Effects of potential trap crops and planting date on soil infestation with potato cyst nematodes and root‐knot nematodes
Authors: SCHOLTE K , VOS J 
Published: July 2006

SummaryIn 1997 and 1998 the stimulation of hatch of potato cyst nematodes (PCN) by a trap crop was studied at various times during the growing season in a container and a field experiment. Solanum nigrum‘90‐4750‐188’was used as the trap crop in both experiments and was sown on 1 May, 16 June or 1 August in two successive years on different plots. Neither experiment revealed much seasonal variation in hatchability of PCN juveniles under a trap crop. In the container experiment, the hatch of the Globodera pallida Pa3 population was equally and strongly stimulated (89%) at all sowing dates in both years, except for the 1 August sowing in 1998 (when the hatch was 77% under extremely wet soil conditions). In the control treatment with non‐hosts (flax followed by barley) the total spontaneous hatch was 50% over 2 yr. In the field experiment, the hatch of PCN, averaged over the four populations, was also equally stimulated (71%) at all sowing dates in both years. In the control treatment with non‐hosts (flax‐barley) the total spontaneous hatch was 36% over 2 yr. Total hatch under the trap crop over 2 yr varied between the four PCN populations from 63% to 80%.In 1998 and 1999, control of potato cyst nematodes (PCN) by the potential trap crops Solanum sisymbriifolium and S. nigrum‘90‐4750‐188’was studied in the field. Potato was also included as a trap crop. In the 1998 experiment, potato, S. sisymbriifolium and S. nigrum strongly stimulated the hatch of PCN compared with the non‐host white mustard (Sinapis alba). Roots of potato and white mustard were mainly found in the top 10 cm of soil, whereas roots of S. sisymbriifolium and S. nigrum were also abundant at depths of 10–20 cm and 20–30 cm. In the 1999 experiment, soil infestation with PCN decreased markedly with potato and S. sisymbriifolium as trap crops. In plots moderately to severely infested with 2‐yr old cysts (2–29 juveniles ml−1 air dried soil), potato reduced soil infestation by 87% and S. sisymbriifolium by 77%. In plots moderately to severely infested with 1‐yr old cysts the reductions were 74% and 60%, respectively. The reduction was least on plots very severely infested with PCN (110–242 juveniles ml−1 soil): 69% and 52% for potato and S. sisymbriifolium, respectively. Soil infestations of plots that were initially slightly to severely infested with the root‐knot nematode Meloidogyne hapla were greatly reduced under fallow and S. sisymbriifolium but increased under potato. From these and previous experiments it was concluded that, for several reasons, S. sisymbriifolium is a promising trap crop.
Effect of sowing date on the optimum plant density of winter wheat
Authors: SPINK J H , SEMERE T , SPARKES D L , WHALEY J M , FOULKES M J , CLARE R W , SCOTT R K 
Published: July 2006

SummaryPressure on financial margins in UK wheat production is driving a review of all inputs, and seed represents one of the largest financial inputs in wheat production. The potential savings through exploiting the crop's ability to compensate for reduced population are, therefore, attractive. Field experiments were carried out at ADAS Rosemaund (Herefordshire, UK) in 1996/97, 1997/98 and 1998/99 to investigate the effect of sowing date on dry matter growth and yield responses of winter wheat to reduced plant population. There were three target sowing dates (late‐Septembr, mid‐October and mid‐November), six seed rates (20, 40, 80, 160, 320 and 640 seeds m−2) and four varieties (Cadenza, Haven, Soissons and Spark). Grain yield was significantly affected by plant population with a mean reduction from 9.2 to 5.5 t ha−1 as plant number was reduced from 336 to 13 m−2. In addition, there was a significant interaction between plant density and sowing date. There was, however, no interaction between variety and plant population in terms of yield, except when lodging affected high plant populations of lodging susceptible varieties. The experiments demonstrated scope for reducing plant populations below the current target of 250–300 plants m−2; however, the degree of reduction was dependent on sowing date. Over the three years, the average economic optimum plant density was 62 plants m−2 for late‐September, 93 plants m−2 for mid‐October, and 139 plants m−2 for mid‐November sowings. Compensation for reduced population was due to increased shoot number per plant, increased grain number per ear and to a lesser extent increased grain size. Higher economic optimum plant densities at later sowing dates were due to reduced tiller production and hence ear number per plant. The other compensatory mechanisms were unaffected by sowing date.
Effects of sodium on mineral nutrition in rose plants
Authors: LORENZO H , CID M C , SIVERIO J M , RUANO M C 
Published: July 2006

SummaryThe effects of sodium (Na+) ion concentration on shoot elongation, uptake of ammonium (NH4+) and nitrate (NO3−) and the activities of nitrate reductase (NR) and glutamine synthetase (GS) were studied in rose plants (Rosa hybrida cv. “Lambada”).The results showed that shoot elongation was negatively correlated with sodium concentration, although no external symptoms of toxicity were observed. Nitrate uptake decreased at high sodium levels, specifically at 30 meq litre4 of sodium. As flower development was normal under high saline conditions, this could suggest that nitrogen was being mobilised from shoot and leaf reserves. Ammonium uptake was not affected by any of the salt treatments applied probably because it diffuses through the cell membrane at low concentrations. Nitrate reductase activity was reduced by 50% at 30 meq litre 1 compared with control treatment, probably due to a decrease in the free nitrate related to nitrate uptake pattern. None of the salt treatments used affected total leaf GS activity (both chloroplastic and cytosolic isoforms) or leaf NPK mineral contents. Nitrate reductase activity in leaves increased at 10 meq litre−1 of sodium and GS activity in roots (cytosolic isoform only) followed the same pattern as NR. It is suggested that the activation of both enzymes at low salt level could be attributed to the beneficial effect of increased sulphur in the nutrient solutions.
Effects of cultivar and fungicides on stem‐base pathogens, determined by quantitative PCR, and on diseases and yield of wheat
Authors: BATEMAN G L , EDWARDS S G , MARSHALL J , MORGAN L W , NICHOLSON P , NUTTALL M , PARRY D W , SCRANCHER M , TURNER A S 
Published: July 2006

SummaryThe polymerase chain reaction (PCR) was used to identify and quantify all fungal pathogens of wheat (Triticum aestivum) stem bases in nine field experiments at three locations in England. The main aim was to apply quantitative PCR to provide robust data on the efficacy of new fungicides against the individual components of the stem‐base disease complex. Cyprodinil most effectively controlled eyespot by decreasing both pathogens, Tapesia yallundae and T. acuformis (the most widespread species), and sometimes contributed to increased yields. Prochloraz controlled eyespot less consistently, its effectiveness dependent mainly on the presence of T. yallundae or on rainfall events soon after application. Azoxystrobin contributed to yield increases most consistently. Although it decreased sharp eyespot and its pathogen, Rhizoctonia cerealis, these effects were insufficient to account for much of the yield increases. The effects of fungicides on eyespot were sometimes greatest on the most susceptible cultivars. Amounts of Tapesia DNA were usually consistent with cultivar susceptibility ratings. The only pathogens of brown foot rot present in significant amounts were Microdochium nivale vars nivale and majus. They appeared not to affect yield or to respond greatly to fungicides. The susceptibility of cultivars to these pathogens was sometimes similar to their susceptibility to eyespot, suggesting that they may respond to the same host resistance genes or may in some cases be secondary colonisers of eyespot‐infected plants.
Comparison of damage levels caused by Radopholus similis and Helicotylenchus multicinctus on bananas in Uganda
Authors: BAREKYE A , KASHAIJA I N , TUSHEMEREIRWE W K , ADIPALA E 
Published: July 2006

AbstractField surveys were done in 1997 and 1998 in Masaka district, Uganda, an area which is experiencing a decline in banana production, to assess level of damage caused by nematodes Radopholus similis and Helicotylenchus multicinctus at farm level. Ten farms within a radius of 2 km were selected and nematode damage assessed. The major nematodes encountered were Pratylenchus goodeyi, R. similis and H. multicinctus. P. goodeyi and H. multicinctus were more abundant than R. similis but R. similis had a stronger and significant correlation with root damage. A subsequent pot trial examined pathogenicities of R. similis and H. multicinctus in pure and mixed cultures on tissue cultured‐banana plantlets. R. similis alone and in mixed population reduced root fresh weight significantly, and the percentage of root necrosis ranged between 22.8–41.6% and 18.3–45.5% for March 1998 and March 1999 trials, respectively. The difference in damage caused by R. similis alone and in mixed population was not statistically significant, and was higher than the damage caused by H. multicinctus alone. There were no significant differences in pathogenicity among the R. similis isolates from different parts of Uganda.
The potential of some adjuvants in promoting infection with Verticillium lecanii: laboratory bioassays with Myzus persicae
Authors: WILLIAMS M E DE COURCY , EDMONDSON R N , GILL G 
Published: July 2006

SummaryThe potential of 14 adjuvants, including mineral oils, vegetable oils, stickers, spreaders, surfactants and nutrients, in promoting the virulence of the entomopathogenic fungus Verticillium lecanii were compared relative to a commercial formulation of the pathogen. The rate of infection over time with each adjuvant relative to the commercial formulation was tested using the peach potato aphid Myzus persicae. The proportion of infected aphids was modelled binomially with a logistic rate function assumed for the proportion infected over the time period of the experiment. Four of the adjuvant treatments, Codacide, skimmed milk, glycerol and Cutinol together with the commercial control had similar logistic slope parameters and were modelled using parallel regressions. The parallel regressions model showed significant differences between the intercepts with both glycerol and Cutinol significantly better than V. lecanii alone. Glycerol had a more positive intercept than Cutinol but the difference was not statistically significant. Although highly variable, the numbers of progeny produced by the treated aphids were significantly reduced by all the treatments relative to untreated control aphids. Glycerol and Cutinol were the only treatments that significantly reduced the number of progeny relative to the V. lecanii control.
Changes in the incidence and severity of Cassava mosaic virus disease, varietal diversity and cassava production in Uganda
Authors: OTIM‐NAPE G W , ALICAI T , THRESH J M 
Published: July 2006

SummaryA survey in 1994 assessed the incidence and severity of Cassava mosaic virus disease (CMD) in Uganda and the changes that had occurred since the previous survey in 1990–92. Three counties in each of 27 districts were selected and 15 fields were assessed per county. CMD occurred in each of the 1215 fields surveyed and the overall incidence within fields was 64% compared with 52% in the same districts in 1990–92. Mean incidence differed significantly between districts and between counties within some districts. The incidence and severity of CMD had increased in 20 and 23 of the 27 districts, respectively, compared with 1990–92, indicating the continued progress of the epidemic that was first reported in Uganda in 1988. In all but three districts, there had been a decrease in the total area of cassava. The number of different varieties that predominated in one or more fields had increased in 17 districts compared with 1990–92, although the total number of varieties encountered was little changed. Ebwanateraka was again the most widely grown variety but it was recorded less frequently and predominated or was co‐dominant in only two districts in 1994 compared with seven in 1990–92. The biggest decrease in the cultivation of Ebwanateraka had occurred in districts where there was a high incidence of CMD in 1990–92.
Expression of tomato Cf genes and their corresponding avirulence genes in transgenic tobacco plants using nematode responsive promoters
Authors: BERTIOLI DAVID J , GUIMARÃES PATRICIAM , JONES JONATHON D G , THOMAS COLWYNM , BURROWS PAUL R , MONTE DAMARES C , LEAL‐BERTIOLI SORAYA C DE M 
Published: July 2006

SummaryIn this study two plant resistance genes, Cf‐4 and Cf‐9, were expressed in transgenic plants together with their corresponding pathogen avirulence genes Avr4 and Avr9. Three nematode responsive promoters (4xB5+A, A0.3TobRB7 and 35S) in different combinations were used to control the expression of these transgenes. According to previous descriptions of the activity of these promoters, for the promoter combinations used, co‐expression would be expected to occur only in the feeding sites of root‐knot nematodes, and not in uninfected plants. This being the case, it was predicted that transgenic plants which express a hypersensitive response, induced by nematode feeding, specifically at the feeding site could be engineered. However, transgenic plants that harbored both resistance and avirulence gene constructs underwent spontaneous necrosis, revealing new features of promoter activity. We show that the pattern of hypersensitive response was dependent upon the combination of promoters used to control the expression of the Cf and Avr genes, transgene position effects and growth conditions. Although activity of the Cf genes has only previously been reported from aerial parts of the plant, here we present evidence that both Cf‐9 and Cf‐4 are active in tobacco roots.