Location of determinants of stability to neomycin and kanamycin as well as DNA segments, responsible for amplification in Streptomyces plasmids pSU3 and pSU10

The S. rimosus amplifying sequence AUD-Sr1 encodes kanamycin and neomycin resistance, defined in the case of neomycin by aminoglycoside phosphotransferase. Its cloning on plasmid SLP1.2 makes possible the co-amplification of the obtained hybrid plasmids in S. lividans. In our study the regions responsible for resistance to aminoglycoside antibiotics and the capacity for amplification the two hybrid plasmids pSU10 and pSU3 were determined. Experiments on subcloning of the AUD-Sr1 sequence fragments on vector pIJ702 revealed localization of kanamycin and neomycin resistance determinants between PvuII(6) and BglII(7) on the AUD-Sr1 sequence fragments of 2.0 kb length. Two regions responsible for amplification of the hybrid plasmids were detected with deletion and insertion mapping. The first region is localized in the region of the plasmid SLP1.2 BamHI site and the second region is localized on the PstI(4)-PvuII(6) of the AUD-Sr1 sequence fragment of 1.1 kb length.     

Characterization of multiple changes of antibiotic resistance characters in Streptomyces coelicolor A3(2)

Among mutants of Streptomyces coelicolor A3(2) studied which were sensitive to chloramphenicol (Cmls), strains sensitive to a number of antibiotics (ristomycin, tetracycline, polymyxin, lincomycin) amount of 46%. Antibiotic-sensitive mutants are capable to form different classes of resistant revertants with frequency varying from 10(-2) to 10(-6) in independent strains. Ristomycin-sensitive clones (Rims) have been found to occur with high frequency in Cmls strains and Cmlr revertants. Mutations mediating the Rims phenotype are mapped in a locus linked to the gene for resistance to chloramphenicol. The results obtained are discussed, in accordance with the notion about possible role of cml mutation in induction of secondary mutational changes in the genome of S. coelicolor A3(2).     

Stereochemical course of the hydroboration of highly hindered steroidal olefins. A ready synthesis of 14 beta- and 8 alpha,14 beta-steroids

Hydroboration of 5 alpha-cholest-8-ene, 5 alpha,14 beta-cholest-8-ene and 5 alpha,14 beta-cholest-7-ene provides a simple route to oxygenated steroids with 14 beta- and 8 alpha,14 beta- unnatural stereochemistry.     

Synthesis of 7 alpha,12 alpha-dihydroxy-3 alpha- [2-(beta-D-glucopyranosyl)acetyl]-5 beta-cholan-24-oic acid

A C-glucoside of cholic acid was synthesized by the introduction of an acetyl group at position 3 alpha and direct one-pot C-glucosidation using 2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl chloride.     

The capacity of bottle-nosed dolphins for generalization according to a relative sign

In bottle-nosed dolphins by a new modification of previously suggested method, a conditioned reflex was elaborated and consolidated to a relative spatial sign--choice of always left object from two similar ones in conditions of a permanent change of place of this pair of stimuli against the background of one of the sides of an open-air cage. Specialization of the reflex was checked by presentation of a pair of stimuli under different changes of surroundings, including discordance of external orientors and also the way of stimuli presentation. Then the initial objects were substituted by others (12 pairs of stimuli) sharply differing from the initial ones by the form, size, material etc. Retention of adequate choice also at the change of the medium of stimuli presentation, testified to the ability of dolphins of abstraction and generalization by relative sign, i.e. at the choice from two objects of the type "to the right--to the left in general".     

The distance dependence prediction of the Janzen-Connell hypothesis: a meta-analysis

The Janzen-Connell hypothesis explains the maintenance of tropical diversity through the interacting effects of parent-centered dispersal patterns and distance- and density-dependent propagule survival. These effects were thought to support regular spacing of species within tropical forest, enhancing diversity. One of the predictions of the hypothesis is that seed and seedling survival should improve with increased parental distance. Although there are many independent tests of this hypothesis for individual species, there are few synthetic studies that have brought these data together to test its validity across species. This paper reports the results of a meta-analysis of the effect of distance on enhancing propagule survival, employing an odds-ratio effect size metric. We found no general support for the distance-dependent prediction of the hypothesis, and conclude that further testing to explore this hypothesis as a diversity-maintaining mechanism is unnecessary. However, we did find that distance from parent slightly reduces survivorship in the temperate zone, as contrasted with the tropics, and we saw stronger evidence in support of the hypothesis for seedlings than for seeds. The phenomenon of enhanced propagule survival with distance from the parent may be important for the population biology of particular species, but it is not a general phenomenon across communities, life history stages or life forms.     

Mosquito population structure,pathogen surveillance and insecticide resistance monitoring in urban regions of Crete,Greece

BackgroundIn Greece vector borne diseases (VBD) and foremost West Nile virus (WNV) pose an important threat to public health and the tourist industry, the primary sector of contribution to the national economy. The island of Crete, is one of Greece’s major tourist destinations receiving annually over 5 million tourists making regional VBD control both a public health and economic priority.MethodologyUnder the auspices of the Region of Crete, a systematic integrative surveillance network targeting mosquitoes and associated pathogens was established in Crete for the years 2018–2020. Using conventional and molecular diagnostic tools we investigated the mosquito species composition and population dynamics, pathogen infection occurrences in vector populations and in sentinel chickens, and the insecticide resistance status of the major vector species.Principal findingsImportant disease vectors were recorded across the island including Culex pipiens, Aedes albopictus, and Anopheles superpictus. Over 75% of the sampled specimens were collected in the western prefectures potentially attributed to the local precipitation patterns, with Cx. pipiens being the most dominant species. Although no pathogens (flaviviruses) were detected in the analysed mosquito specimens, chicken blood serum analyses recorded a 1.7% WNV antibody detection rate in the 2018 samples. Notably detection of the first WNV positive chicken preceded human WNV occurrence in the same region by approximately two weeks. The chitin synthase mutation I1043F (associated with high diflubenzuron resistance) was recorded at an 8% allelic frequency in Lasithi prefecture Cx. pipiens mosquitoes (sampled in 2020) for the first time in Greece. Markedly, Cx. pipiens populations in all four prefectures were found harboring the kdr mutations L1014F/C/S (associated with pyrethroid resistance) at a close to fixation rate, with mutation L1014C being the most commonly found allele (≥74% representation). Voltage gated sodium channel analyses in Ae. albopictus revealed the presence of the kdr mutations F1534C and I1532T (associated with putative mild pyrethroid resistance phenotypes) yet absence of V1016G. Allele F1534C was recorded in all prefectures (at an allelic frequency range of 25–46.6%) while I1532T was detected in populations from Chania, Rethymnon and Heraklion (at frequencies below 7.1%). Finally, no kdr mutations were detected in the Anopheles specimens included in the analyses.Conclusions/SignificanceThe findings of our study are of major concern for VBD control in Crete, highlighting (i) the necessity for establishing seasonal integrated entomological/pathogen surveillance programs, supporting the design of targeted vector control responses and; ii) the need for establishing appropriate insecticide resistance management programs ensuring the efficacy and sustainable use of DFB and pyrethroid based products in vector control.