Molecular and Physiological Properties Associated with Zebra Complex Disease in Potatoes and Its Relation with Candidatus Liberibacter Contents in Psyllid Vectors

Zebra complex (ZC) disease on potatoes is associated with Candidatus Liberibacter solanacearum (CLs), an α-proteobacterium that resides in the plant phloem and is transmitted by the potato psyllid Bactericera cockerelli (Šulc). The name ZC originates from the brown striping in fried chips of infected tubers, but the whole plants also exhibit a variety of morphological features and symptoms for which the physiological or molecular basis are not understood. We determined that compared to healthy plants, stems of ZC-plants accumulate starch and more than three-fold total protein, including gene expression regulatory factors (e.g. cyclophilin) and tuber storage proteins (e.g., patatins), indicating that ZC-affected stems are reprogrammed to exhibit tuber-like physiological properties. Furthermore, the total phenolic content in ZC potato stems was elevated two-fold, and amounts of polyphenol oxidase enzyme were also high, both serving to explain the ZC-hallmark rapid brown discoloration of air-exposed damaged tissue. Newly developed quantitative and/or conventional PCR demonstrated that the percentage of psyllids in laboratory colonies containing detectable levels of CLs and its titer could fluctuate over time with effects on colony prolificacy, but presumed reproduction-associated primary endosymbiont levels remained stable. Potato plants exposed in the laboratory to psyllid populations with relatively low-CLs content survived while exposure of plants to high-CLs psyllids rapidly culminated in a lethal collapse. In conclusion, we identified plant physiological biomarkers associated with the presence of ZC and/or CLs in the vegetative potato plant tissue and determined that the titer of CLs in the psyllid population directly affects the rate of disease development in plants

Development of an app for processing data on wildlife density in the field

It is essential to provide tools to wildlife professionals and researchers in order to facilitate data collection on wildlife density estimation following standardized protocols in the field. This is relevant for efficient harmonized data management systems, from the field to final reporting. Our main objective was to facilitate the collection of information in the field using established density estimation protocols. The specific objectives were (i) to evaluate and use already existing data registration IT tools for collecting and storing the data in the field; (ii) to make these data available in real time (cloud-based solution), and (iii) being flexible enough to incorporate new protocols and species, as methods (such as camera trap-based) and needs continuously evolves. We improved an already existing tool, Spatial Monitoring and Reporting Tool (SMART; https://smartconservationtools.org/). It is an open source software, which allows easily collect, visualize, store, analyze, report and act on a wide range of field data relevant for wildlife monitoring. The integration of SMART tools on EOW was successfully done for (i) distance sampling, (ii) hunting data and (iii) camera trap protocols. ENETWILD, therefore, made now available new IT functionalities to wildlife professionals and researchers to facilitate and harmonize wildlife data collection systems.EFSA-Q-2022-00044Peer reviewe

What are the costs of learning? Modest trade-offs and constitutive costs do not set the price of fast associative learning ability in a parasitoid wasp

International audienceLearning ability has been associated with energetic costs that typically become apparent through trade-offs in a wide range of developmental, physiological, and life-history traits. Costs associated with learning ability can be either constitutive or induced, depending on whether they are always incurred or only when information is actively learned and memorized. Using lines of the parasitoid wasp Nasonia vitripennis that were selected for fast associative learning ability, we assessed a range of traits that have previously been identified as potential costs associated with learning. No difference in longevity, lipid reserves, tibia length, egg load, or fecundity was observed between the selected and control lines. All of these traits are considered to potentially lead to constitutive costs in the setup of this study. A gradual reversal to baseline learning after two forms of relaxed selection was indicative of a small constitutive cost of learning ability. We also tested for a trade-off with other memory types formed at later stages, but found no evidence that the mid-term memory that was selected for caused a decrease in performance of other memory types. In conclusion, we observe only one minor effect of a constitutive cost and none of the other costs and trade-offs that are reported in the literature to be of significant value in this case. We, therefore, argue for better inclusion of ecological and economic costs in studies on costs and benefits of learning ability

An internet-based bioinformatics toolkit for plant biosecurity diagnosis and surveillance of viruses and viroids

Background Detection and preventing entry of exotic viruses and viroids at the border is critical for protecting plant industries trade worldwide. Existing post entry quarantine screening protocols rely on time-consuming biological indicators and/or molecular assays that require knowledge of infecting viral pathogens. Plants have developed the ability to recognise and respond to viral infections through Dicer-like enzymes that cleave viral sequences into specific small RNA products. Many studies reported the use of a broad range of small RNAs encompassing the product sizes of several Dicer enzymes involved in distinct biological pathways. Here we optimise the assembly of viral sequences by using specific small RNA subsets. Results We sequenced the small RNA fractions of 21 plants held at quarantine glasshouse facilities in Australia and New Zealand. Benchmarking of several de novo assembler tools yielded SPAdes using a kmer of 19 to produce the best assembly outcomes. We also found that de novo assembly using 21–25 nt small RNAs can result in chimeric assemblies of viral sequences and plant host sequences. Such non-specific assemblies can be resolved by using 21–22 nt or 24 nt small RNAs subsets. Among the 21 selected samples, we identified contigs with sequence similarity to 18 viruses and 3 viroids in 13 samples. Most of the viruses were assembled using only 21–22 nt long virus-derived siRNAs (viRNAs), except for one Citrus endogenous pararetrovirus that was more efficiently assembled using 24 nt long viRNAs. All three viroids found in this study were fully assembled using either 21–22 nt or 24 nt viRNAs. Optimised analysis workflows were customised within the Yabi web-based analytical environment. We present a fully automated viral surveillance and diagnosis web-based bioinformatics toolkit that provides a flexible, user-friendly, robust and scalable interface for the discovery and diagnosis of viral pathogens. Conclusions We have implemented an automated viral surveillance and diagnosis (VSD) bioinformatics toolkit that produces improved viruses and viroid sequence assemblies. The VSD toolkit provides several optimised and reusable workflows applicable to distinct viral pathogens. We envisage that this resource will facilitate the surveillance and diagnosis viral pathogens in plants, insects and invertebrates

Hepatobiliary transport of glutathione and glutathione conjugate in rats with hereditary hyperbilirubinemia.

TR- mutant rats have an autosomal recessive mutation that is expressed as a severely impaired hepatobiliary secretion of organic anions like bilirubin-(di)glucuronide and dibromosulphthalein (DBSP). In this paper, the hepatobiliary transport of glutathione and a glutathione conjugate was studied in normal Wistar rats and TR- rats. It was shown that glutathione is virtually absent from the bile of TR- rats. In the isolated, perfused liver the secretion of glutathione and the glutathione conjugate, dinitrophenyl-glutathione (GS-DNP), from hepatocyte to bile is severely impaired, whereas the sinusoidal secretion from liver to blood is not affected. The secretion of GS-DNP was also studied in isolated hepatocytes. The secretion of GS-DNP from cells isolated from TR- rat liver was significantly slower than from normal hepatocytes. Efflux of GS-DNP was a saturable process with respect to intracellular GS-DNP concentration: Vmax and Km for efflux from TR- cells was 498 nmol/min.g dry wt and 3.3 mM, respectively, as compared with 1514 nmol/min.g dry wt and 0.92 mM in normal hepatocytes. These results suggest that the canalicular transport system for glutathione and glutathione conjugates is severely impaired in TR- rats, whereas sinusoidal efflux is unaffected. Because the defect also comes to expression in isolated hepatocytes, efflux of GS-DNP from normal hepatocytes must predominantly be mediated by the canalicular transport mechanism, which is deficient in TR- rats

Strain differences rather than species differences contribute to variation in associative learning ability in Nasonia

Insect species display a large range of inter- and intraspecific variation in learning and memory retention. Variation in associative learning ability has also been reported for three species in the parasitoid wasp genus Nasonia, most notably between Nasonia vitripennis and Nasonia giraulti, for which inbred isogenic strains have been established and studied intensively. We addressed the question how learning and memory of such isogenic strains compare to the phenotypes found in genetically diverse strains of these species. We recorded memory retention of both isogenic and genetically diverse strains of two species at 4–120 h after either olfactory or visual conditioning. Memory retention typically declined over time, but the pattern of decline differed consistently between strains. The isogenic N. vitripennis strain formed long-lasting (>5 days) memory, whereas the isogenic N. giraulti strain lost its memory after 48 h. Yet, genetically diverse strains of both species formed long-lasting memory. Memory retention patterns of strains were independent of sensory modality of the conditioned stimulus for all strains. These results show that there is variation for associative learning and memory within the two species, but not clear interspecies differences in memory retention. Without a better overview of the natural variation in learning abilities within a species, individual strains, especially isogenic strains with low genetic variability, are not necessarily representative of the species in general.</p