Comparison of Russet Burbank clones from various geographical regions of the United States and Canada

Ten ‘Russet Burbank’ potato clones collected from various geographical regions of the United States and Canada were evaluated for plant and agronomic characteristics for two years at Aberdeen, Idaho. Clonal differences were detected for emergence time, stem number per hill, expression of Verticillium symptoms, some measures of yield, and percentage of tubers with hollow heart. Eight of the ten clones were quite similar. Differences were slight or found only in a few characteristics. One clone, collected from northern Idaho, was similar to the homogenous eight clones in all respects except yield, which was probably due to chronic PVX infection throughout the trial period. Another clone, collected from New Brunswick, was distinct from all other clones and was markedly inferior with respect to many of the characteristics measured when grown in Idaho.     

Deposition and redistribution of fungicides applied by air and chemigation for control of late blight in commercial potato fields

The fungicides metiram, mancozeb, metiram + triphenyltin hydroxide, propamocarb hydrochloride + chlorothalonil, dimethomorph + mancozeb, cymoxanil + mancozeb, and chlorothalonil were applied by aircraft and through center-pivot irrigation systems (chemigation) to replicated plots in commercial fields of ‘Russet Burbank’ potato. Fungicide deposition and redistribution were indirectly determined by inoculation of excised leaves withPhytophthora infestans and directly by chlorothalonil residue analysis from upper, middle, and lower crop canopies. The effectiveness of two surfactants added with fungicide and applied by aircraft, an increased water volume rate used by aircraft, and a reduced water volume used with chemigation was also determined. The addition of synthetic latex and siliconepolyether surfactants did not increase efficacy of metiram or mancozeb in controlling late blight when applied by aircraft. The protectant fungicides metiram, mancozeb, and chlorothalonil were not significantly different from dimethomorph + mancozeb, cymoxanil + mancozeb, and propamocarb hydrochloride + chlorothalonil in late blight control when applied by aircraft. However, cymoxanil + mancozeb had limited efficacy when applied by chemigation. Fungicide deposition through the canopy differed when air applications were made before or after canopy closure (row closure). Fungicides applied by aircraft prior to row closure protected the entire canopy; whereas, fungicide application after row closure initially protected the top and middle canopies, and subsequent applications and redistribution of the fungicides were needed for adequate protection throughout the canopy. The fungicides and fungicide mixtures tested were evenly deposited throughout the potato canopy with each chemigation application. Severity of late blight did not differ on leaves treated with mancozeb or chlorothalonil applied by aircraft at water volumes of 47 L/ha and 94 I/ha and then inoculated withP. infestans, nor did severity of late blight differ on inoculated leaves previously treated with chlorothalonil by chemigation at water volumes of 15,145 and 50, 571 L/ha.     

Regulation of cytokine receptors by Golgi N-glycan processing and endocytosis

The Golgi enzyme beta1,6 N-acetylglucosaminyltransferase V (Mgat5) is up-regulated in carcinomas and promotes the substitution of N-glycan with poly N-acetyllactosamine, the preferred ligand for galectin-3 (Gal-3). Here, we report that expression of Mgat5 sensitized mouse cells to multiple cytokines. Gal-3 cross-linked Mgat5-modified N-glycans on epidermal growth factor and transforming growth factor-beta receptors at the cell surface and delayed their removal by constitutive endocytosis. Mgat5 expression in mammary carcinoma was rate limiting for cytokine signaling and consequently for epithelial-mesenchymal transition, cell motility, and tumor metastasis. Mgat5 also promoted cytokine-mediated leukocyte signaling, phagocytosis, and extravasation in vivo. Thus, conditional regulation of N-glycan processing drives synchronous modification of cytokine receptors, which balances their surface retention against loss via endocytosis.     

Resistance to amitraz in the parasitic honey bee mite Varroa destructor is associated with mutations in the β-adrenergic-like octopamine receptor

Varroa destructor is considered a major reason for high loss rate of Western honey bee (Apis mellifera) colonies. To prevent colony losses caused by V. destructor, it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the parasite, resulting in intensive treatment regimens that led to the evolution of resistance in mite populations. To investigate the mechanism of the resistance to amitraz detected in V. destructor mites from French and U.S. apiaries, we identified and characterized octopamine and tyramine receptors (the known targets of amitraz) in this species. The comparison of sequences obtained from mites collected from different apiaries with different treatment regimens, showed that the amino acid substitutions N87S or Y215H in the OctβR were associated with treatment failures reported in French or U.S. apiaries, respectively. Based on our findings, we have developed and tested two high throughput diagnostic assays based on TaqMan technology able to accurately detect mites carrying the mutations in this receptor. This valuable information may be of help for beekeepers when selecting the most suitable acaricide to manage V. destructor.