1,155 research outputs found

    A comparison of new and existing rootstocks to reduce canker of apple trees caused by Neonectria ditissima (Nectriaceae, Hypocreales)

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    The grafting of apple rootstocks on to scions confers benefts including reduced tree size/dwarfng for trellis based growing systems, increased tolerance to physiological stress, and pest and disease management. The current study investigated the efect of rootstock selection on canker and tree death using eight common rootstocks M9 337, M9 337 with Golden Delicious (GD) interstock, M9 EMLA, MM106, M116, M26, Geneva® G11 and G41, in addition to six advanced selections from the NIAB East Malling apple breeding programme EMR-001—EMR-006, all grafted with Gala scions. One of the rootstocks, M9 377 was also grafted with a GD interstock. Two locations in England were selected, the frst at East Malling, Kent, the second, at Newent, Gloucestershire. Several variables were analysed including cumulative numbers of dead trees per rootstock from 2017 to 2020, number of rootstock ‘A type’ cankers, number of scion mainstem ‘B type’ cankers, and number of peripheral ‘C+D+E’ branch cankers at the Kent and Gloucestershire locations in the fourth and fnal assessment year of 2020. Kendall’s rank correlation was used to test if trunk circumference (a measure of tree vigour) and canker were statistically dependant. Results showed that in Kent, there were signifcant diferences between rootstocks for scion B cankers and peripheral C+D+E cankers. There were no signifcant diferences found between rootstocks for rootstock A cankers at Kent, or any of the three canker types in Gloucestershire. There were up to 31.25% dead trees in Kent (EMR-004), and 30% in Gloucestershire (M9 337 with GD interstock, M26), but there were no signifcant diferences in number of dead trees due to rootstock type in either Kent or Gloucestershire. The Kendall’s rank correlation analysis indicated there was almost no dependence of trunk circumference on canker. The three rootstocks with the overall lowest susceptibility to canker were M116, EMR-006, and EMR-004. The industry standard rootstocks M9 EMLA and M9 337 were ranked 12 and 14, and with EMR-001 were the three worst performing rootstocks. The Geneva® rootstocks G11 was ranked 6, and G41 was ranked 11. An interplay of factors are likely involved in the development of canker including location and environmental efects—rainfall, relative humidity, temperature, wind, soil type, topography, aspect, and other seasonal infection processes including pathogen inoculum load, and rainsplash of inoculum between trees and within individual trees, the genetics and physiology of each scion/rootstock combination, water and nutritional status of trees, hormonal and molecular signalling, and orchard management including pruning and removal of cankers

    Wettability characteristics of carbon steel modified with CO2, Nd:YAG, Excimer and high power diode lasers

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    Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of a common mild steel (EN8) was found to effect changes in the wettability characteristics of the steel, namely changes in the measured contact angle. These modifications are related to changes in the surface roughness, changes in the surface oxygen content and changes in the surface energy of the mild steel. The wettability characteristics of the selected mild steel could be controlled and/or modified by laser surface treatment. A correlation between the change of the wetting properties of the mild steel and the laser wavelength was found

    Studies on the expression of a cloned Staphylococcus aureus protein A gene in Escherichia coli

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    The gene coding for staphylococcal protein A has been cloned and the nucleotide sequence coding for the structural gene and its 5' flanking region determined. The DNA sequence showed the gene to be composed of a series of repetitive sequences, with five 120 nucleotide repeats comprising the 5' part of the structural gene and ten 24 nucleotide repeats in a continuous sequence at the 3’ terminus. Analysis of codon usage of the gene and comparison with other S. aureus genes revealed that spa showed a higher degree of homology with S. aureus plasmid genes than with chromosomally- located genes. Comparison with the reported codon preference in E.coli showed spa to have a similar bias, except for the leu codon. An open reading frame of the spa structural gene showed 508 a.a residues, with a predicted protein molecular weight of 55,426. The N-terminal signal peptide comprised the first 36 amino acids. A fifth N-terminal domain (E) was shown to be homologous to the four IgG-binding domains previously reported to constitute the N-terminal portion of SpA. The C-terminal part of SpA was shown to consist of two structurally different regions: an N-terminal repetitive region (Xr) composed of ten octapeptide repeats which are hydrophilic and have been proposed to span the Gram-positive cell wall, followed by a single domain (Xc), 58 a.a in length, whose C-terminal portion contains 20 hydrophobic residues, suggesting anchorage on the cell membrane. Enhanced production of SpA in E. coli has been achieved by placing the E. coli lac promoter immediately upstream of the spa gene. This has allowed yields as high as 1.5g of SpA per litre of culture to be obtained from 150-litre batch fermenters. Problems were encountered during large-scale fermentation, as the recombinant clones were found to be extremely fragile when producing high levels of SpA. Characterisation of the recombinant SpA indicated a molecular weight of 54,000 for the full length protein, compared with 56,000 for SpA produced in S. aureus. SDS-PAGE analysis of the IgG-binding proteins revealed extensive proteolysis of the recombinant SpA. Comparitive analysis of the IgG-binding polypeptides encoded by a truncated spa gene (lacking 69 a.a residues from the C-terminus), together with the determination of the N-terminal amino acid sequence, indicated that proteolysis occurred at the N- terminal portion of the Xc region. Cell fractionation studies and immunoelectronmicroscopy localised the SpA to the periplasm in E. coli. A possible regulatory control region for the spa gene has been localised upstream of the structural gene. The E.coli alkaline phosphatase gene was isolated, cloned and its sequence determined to facilitate the production of SpA-alkaline phosphatase fusion proteins

    Tephritid-microbial interactions to enhance fruit fly performance in sterile insect technique programs

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    Background: The Sterile Insect Technique (SIT) is being applied for the management of economically important pest fruit flies (Diptera: Tephritidae) in a number of countries worldwide. The success and cost effectiveness of SIT depends upon the ability of mass-reared sterilized male insects to successfully copulate with conspecific wild fertile females when released in the field. Methods: We conducted a critical analysis of the literature about the tephritid gut microbiome including the advancement of methods for the identification and characterization of microbiota, particularly next generation sequencing, the impacts of irradiation (to induce sterility of flies) and fruit fly rearing, and the use of probiotics to manipulate the fruit fly gut microbiota. Results: Domestication, mass-rearing, irradiation and handling, as required in SIT, may change the structure of the fruit flies’ gut microbial community compared to that of wild flies under field conditions. Gut microbiota of tephritids are important in their hosts’ development, performance and physiology. Knowledge of how mass-rearing and associated changes of the microbial community impact the functional role of the bacteria and host biology is limited. Probiotics offer potential to encourage a gut microbial community that limits pathogens, and improves the quality of fruit flies. Conclusions: Advances in technologies used to identify and characterize the gut microbiota will continue to expand our understanding of tephritid gut microbial diversity and community composition. Knowledge about the functions of gut microbes will increase through the use of gnotobiotic models, genome sequencing, metagenomics, metatranscriptomics, metabolomics and metaproteomics. The use of probiotics, or manipulation of the gut microbiota, offers significant opportunities to enhance the production of high quality, performing fruit flies in operational SIT programs

    Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale

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    Above-ground cosmic-ray neutron measurements provide an opportunity to infer soil moisture at the subkilometer scale. Initial efforts to assimilate those measurements have shown promise. This study expands such analysis by investigating (1) how the information from aboveground cosmic-ray neutrons can constrain the soil moisture at distinct depths simulated by a land surface model, and (2) how changes in data availability (in terms of retrieval frequency) impact the dynamics of simulated soil moisture profiles. We employ ensemble data assimilation techniques in a “nearly-identical twin” experiment applied at semi-arid shrubland, rainfed agricultural field, and mixed forest biomes in the USA. The performance of the Noah land surface model is compared with and without assimilation of observations at hourly intervals, as well as every 2 days. Synthetic observations of aboveground cosmic-ray neutrons better constrain the soil moisture simulated by Noah in root-zone soil layers (0–100 cm), despite the limited measurement depth of the sensor (estimated to be 12–20 cm). The ability of Noah to reproduce a “true” soil moisture profile is remarkably good, regardless of the frequency of observations at the semi-arid site. However, soil moisture profiles are better constrained when assimilating synthetic cosmic-ray neutron observations hourly rather than every 2 days at the cropland and mixed forest sites. This indicates potential benefits for hydrometeorological modeling when soil moisture measurements are available at a relatively high frequency. Moreover, differences in summertime meteorological forcing between the semi-arid site and the other two sites may indicate a possible controlling factor to soil moisture dynamics in addition to differences in soil and vegetation properties

    Fibrillin-1 regulates the bioavailability of TGFβ1

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    We have discovered that fibrillin-1, which forms extracellular microfibrils, can regulate the bioavailability of transforming growth factor (TGF) β1, a powerful cytokine that modulates cell survival and phenotype. Altered TGFβ signaling is a major contributor to the pathology of Marfan syndrome (MFS) and related diseases. In the presence of cell layer extracellular matrix, a fibrillin-1 sequence encoded by exons 44–49 releases endogenous TGFβ1, thereby stimulating TGFβ receptor–mediated Smad2 signaling. This altered TGFβ1 bioavailability does not require intact cells, proteolysis, or the altered expression of TGFβ1 or its receptors. Mass spectrometry revealed that a fibrillin-1 fragment containing the TGFβ1-releasing sequence specifically associates with full-length fibrillin-1 in cell layers. Solid-phase and BIAcore binding studies showed that this fragment interacts strongly and specifically with N-terminal fibrillin-1, thereby inhibiting the association of C-terminal latent TGFβ-binding protein 1 (a component of the large latent complex [LLC]) with N-terminal fibrillin-1. By releasing LLC from microfibrils, the fibrillin-1 sequence encoded by exons 44–49 can contribute to MFS and related diseases

    Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale

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    Above-ground cosmic-ray neutron measurements provide an opportunity to infer soil moisture at the subkilometer scale. Initial efforts to assimilate those measurements have shown promise. This study expands such analysis by investigating (1) how the information from aboveground cosmic-ray neutrons can constrain the soil moisture at distinct depths simulated by a land surface model, and (2) how changes in data availability (in terms of retrieval frequency) impact the dynamics of simulated soil moisture profiles. We employ ensemble data assimilation techniques in a “nearly-identical twin” experiment applied at semi-arid shrubland, rainfed agricultural field, and mixed forest biomes in the USA. The performance of the Noah land surface model is compared with and without assimilation of observations at hourly intervals, as well as every 2 days. Synthetic observations of aboveground cosmic-ray neutrons better constrain the soil moisture simulated by Noah in root-zone soil layers (0–100 cm), despite the limited measurement depth of the sensor (estimated to be 12–20 cm). The ability of Noah to reproduce a “true” soil moisture profile is remarkably good, regardless of the frequency of observations at the semi-arid site. However, soil moisture profiles are better constrained when assimilating synthetic cosmic-ray neutron observations hourly rather than every 2 days at the cropland and mixed forest sites. This indicates potential benefits for hydrometeorological modeling when soil moisture measurements are available at a relatively high frequency. Moreover, differences in summertime meteorological forcing between the semi-arid site and the other two sites may indicate a possible controlling factor to soil moisture dynamics in addition to differences in soil and vegetation properties

    The flux and provenance of dust delivered to the SW Pacific during the last glacial maximum

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    The funding for the TAN1106 voyage was from the Coasts and Oceans Physical Resources program awarded to the National Institute of Water and Atmospheric Research, New Zealand. This work was funded by NERC studentship NE/L002531/1 to R.S. and NERC grant NE/J021075/1 to G.L.F. R.G. and A.B. were supported by NERC grant NE/M004619/1 awarded to A.B.Atmospheric dust is a primary source of iron (Fe) to the open ocean, and its flux is particularly important in the high nutrient, low chlorophyll (HNLC) Southern Ocean where Fe currently limits productivity. Alleviation of this Fe limitation in the Subantarctic Zone of the Atlantic by increased dust-borne Fe supply during glacial periods has been shown to increase primary productivity. However, previous work has found no such increase in productivity in the Pacific sector. In order to constrain the relative importance of Southern Ocean Fe fertilization on glacial-interglacial carbon cycles, records of dust fluxes outside of the Atlantic sector of the Southern Ocean at the Last Glacial Maximum (LGM) are required. Here we use grain size and U-series analyses to reconstruct lithogenic and CaCO3 fluxes, and Nd, Sr and Pb isotopes to ascertain the provenance of terrigenous material delivered to four deep-water cores in the SW Pacific Ocean over the last ~30kyr. We find evidence for an increase in the relative proportion of fine-grained (0.5-12 ?m) terrigenous sediment and higher detrital fluxes during the LGM compared to the Holocene. The provenance of the LGM dust varied spatially, with an older, more "continental" signature (low εNd, high 87Sr/86Sr) sourced from Australia in the northern cores, and a younger, more volcanogenic source in the southern cores (high εNd, low 87Sr/86Sr), likely sourced locally from New Zealand. Given this increase in lithogenic flux to the HNLC subantarctic Pacific Southern Ocean during the LGM, factors besides Fe-supply must have regulated the biological productivity here.Publisher PDFPeer reviewe
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