Susceptibility of Cypriot Tuta absoluta populations to four targeted insecticides and control failure likelihood

Tuta absoluta, known as the South American tomato pinworm, is one of the most disastrous pests of tomato cultivations, presently menacing tomato cultivations worldwide. In 2006, T. absoluta invaded Spain from South America. Since then, it was rapidly spread to most European, African and Asian countries. Such alien invasive species can minimize crop production, whereas the increasing use of insecticides raises various environmental concerns as well as on control costs, control failure and the toxicity to non‐target organisms. The S. American tomato pinworm is mostly controlled by chemical insecticides, and failure to control it is not a rare phenomenon. Resistance to numerous insecticides has been reported and is mainly due to the fact that farmers do not follow a sustainable resistance management scheme. Several examples have been reported from several countries where the tomato pinworm is present. In order to develop a successful insecticide resistance management (IRM) strategy for any major pest, one needs to identify the baseline toxicity to insecticides and then monitor susceptibility levels . In Cyprus, the current status of susceptibility levels to the main insecticides that are used to control T. absoluta has never been studied before. Herein, nine Cypriot populations of the pest were subjected to laboratory bioassays between 2016 and 2018 using the main insecticides applied against it. We found that the insecticides chlorantraniliprole and indoxacarb could not control the Cypriot T. absoluta populations anymore, with a resistance ratio (RR) >28 and 3–23, respectively. Furthermore, mortality achieved by those two insecticides was 20.6%–72% for chlorantraniliprole and 27.5%–78% for indoxacarb. However, the insecticides emamectin benzoate and spinosad are very effective, since mortality to both of them ranged between 99.5% and 100%.     

Phytoplankton and Nutrients in the River Strymon,Greece

Phytoplankton species composition, biomass, diversity, nutrients and chlorophyll a were studied at monthly intervals from December 1991 to December 1992 in a selected area of the river Strymon. SRP ranged from 53 to 182 μg⁻¹ l⁻¹ and DIN from 265 to 850 μg⁻¹ I⁻¹. Nutrient values do not indicate strong anthropogenic effects. Chlorophyll α ranged from 1.0 to 35.3 μg⁻¹ I⁻¹ and followed the temporal distribution of total phytoplankton biomass. Phytoplankton biomass exhibited maxima in winter – spring and summer (6.8 g m⁻³ in December 1991, 4.8 g m⁻³ in April 1992 and 9.3 g m⁻³ in August 1992) composed mainly of diatoms, chlorphytes, cyanophytes and dinophytes. Nanoplankton was the most important component of phytoplankton biomass (69.5%) revealing increased values in winter and early spring. Phytoplankton diversity ranged from 0.8 to 3.2. The hydrological conditions in the river Strymon seem to be appropriate for the algae to reproduce themselves in the running water and so, to develop as a true potamoplankton. However, significant populations of phytoplankton must have been carried out from the Kerkini reservoir, situated at the north of the sampling station. The phytoplankton species composition and their periodicity in the river resemble those of typical, large, lowland and nutrient – rich rivers of Europe.     

In vitro interaction network of a synthetic gut bacterial community

A key challenge in microbiome research is to predict the functionality of microbial communities based on community membership and (meta)-genomic data. As central microbiota functions are determined by bacterial community networks, it is important to gain insight into the principles that govern bacteria-bacteria interactions. Here, we focused on the growth and metabolic interactions of the Oligo-Mouse-Microbiota (OMM¹²) synthetic bacterial community, which is increasingly used as a model system in gut microbiome research. Using a bottom-up approach, we uncovered the directionality of strain-strain interactions in mono- and pairwise co-culture experiments as well as in community batch culture. Metabolic network reconstruction in combination with metabolomics analysis of bacterial culture supernatants provided insights into the metabolic potential and activity of the individual community members. Thereby, we could show that the OMM¹² interaction network is shaped by both exploitative and interference competition in vitro in nutrient-rich culture media and demonstrate how community structure can be shifted by changing the nutritional environment. In particular, Enterococcus faecalis KB1 was identified as an important driver of community composition by affecting the abundance of several other consortium members in vitro. As a result, this study gives fundamental insight into key drivers and mechanistic basis of the OMM¹² interaction network in vitro, which serves as a knowledge base for future mechanistic in vivo studies.Subject terms: Microbiome, Microbial ecology     

Protein and lipid composition of a vitellin isolated from eggs of Sparus aurata

The protein and lipid composition of a vitellin isolated from eggs of Sparus aurata were characterized by SDS PAGE, N-terminal sequence analysis and lipid analysis by thin layer chromatography and gas chromatography. The lipoprotein complex contains proteins with apparent molecular weights of 69, 59, 23, 21 and 12 kDa and were characterized as vitellinogenin fragments by N-terminal sequencing. Lipid extraction and analysis indicate an association of cholesterol and phospholipids with the protein subunits. The phospholipids contain fatty acids with 14, 16 and 18 carbon atoms as determined by GC/MS.     

CLIP-170/tubulin-curved oligomers coassemble at microtubule ends and promote rescues

BACKGROUND: CLIP-170 is a microtubule binding protein specifically located at microtubule plus ends, where it modulates their dynamic properties and their interactions with intracellular organelles. The mechanism by which CLIP-170 is targeted to microtubule ends remains unclear today, as well as its precise effect on microtubule dynamics. RESULTS: We used the N-terminal part of CLIP-170 (named H2), which contains the microtubule binding domains, to investigate how it modulates in vitro microtubule dynamics and structure. We found that H2 primarily promoted rescues (transitions from shrinkage to growth) of microtubules nucleated from pure tubulin and isolated centrosomes, and stimulated microtubule nucleation. Electron cryomicroscopy revealed that H2 induced the formation of tubulin rings in solution and curved oligomers at the extremities of microtubules in assembly conditions. CONCLUSIONS: These results suggest that CLIP-170 targets specifically at microtubule plus ends by copolymerizing with tubulin and modulates microtubule nucleation, polymerization, and rescues by the same basic mechanism with tubulin oligomers as intermediates.     

Reversed-phase liquid chromatographic method with fluorescence detection for the simultaneous determination of albendazole sulphoxide, albendazole sulphone and albendazole 2-aminosulphone in sheep plasma

A rapid and sensitive HPLC method for the simultaneous quantification of albendazole sulphoxide (ABZ-SO), albendazole sulphone (ABZ-SO2) and albendazole 2-aminosulphone (ABZ-SO2NH2) in sheep blood plasma has been developed. Plasma samples were extracted with ethyl acetate under alkaline conditions. Separation was achieved on a C18 reversed-phase analytical column, in the presence of positively- (tetra-n-butylammonium hydrogen sulphate) and negatively-charged (octanesulphonate sodium) pairing ions, while detection was performed fluorometrically. Excitation and emission wavelengths were 290 and 320 nm, respectively. Limits of quantification were defined at 39 ng/ml for ABZ-SO, 4.95 ng/ml for ABZ-SO2 and 4 ng/ml for ABZ-SO2NH2. Accuracy data, in terms of recovery efficiency showed overall values (+/- S.E.M.) of 85.6 +/- 1.0% for ABZ-SO, 100.0 +/- 1.0% for ABZ-SO2 and 89.1 +/- 0.6% for ABZ-SO2NH2. The method was successfully applied to quantitatively determine the three albendazole metabolites in plasma samples collected from sheep that had been orally administered albendazole.     

The 1.76 A resolution crystal structure of glycogen phosphorylase B complexed with glucose, and CP320626, a potential antidiabetic drug

CP320626, a potential antidiabetic drug, inhibits glycogen phosphorylase in synergism with glucose. To elucidate the structural basis of synergistic inhibition, we determined the structure of muscle glycogen phosphorylase b (MGPb) complexed with both glucose and CP320626 at 1.76 A resolution, and refined to a crystallographic R value of 0.211 (R(free)=0.235). CP320626 binds at a novel allosteric site, which is some 33 A from the catalytic site, where glucose binds. The high resolution structure allows unambiguous definition of the conformation of the 1-acetyl-4-hydroxy-piperidine ring supported by theoretical energy calculations. Both CP320626 and glucose promote the less active T-state, thereby explaining their synergistic inhibition. Structural comparison of MGPb--glucose--CP320626 complex with liver glycogen phosphorylase a (LGPa) complexed with a related compound (CP403700) show that the ligand binding site is conserved in LGPa.