Estimates of DNA strand breakage in bottlenose dolphin (Tursiops truncatus) leukocytes measured with the Comet and DNA diffusion assays

The analysis of DNA damage by mean of Comet or single cell gel electrophoresis (SCGE) assay has been commonly used to assess genotoxic impact in aquatic animals being able to detect exposure to low concentrations of contaminants in a wide range of species. The aims of this work were 1) to evaluate the usefulness of the Comet to detect DNA strand breakage in dolphin leukocytes, 2) to use the DNA diffusion assay to determine the amount of DNA strand breakage associated with apoptosis or necrosis, and 3) to determine the proportion of DNA strand breakage that was unrelated to apoptosis and necrosis. Significant intra-individual variation was observed in all of the estimates of DNA damage. DNA strand breakage was overestimated because a considerable amount (~29%) of the DNA damage was derived from apoptosis and necrosis. The remaining DNA damage in dolphin leukocytes was caused by factors unrelated to apoptosis and necrosis. These results indicate that the DNA diffusion assay is a complementary tool that can be used together with the Comet assay to assess DNA damage in bottlenose dolphins.     

Responses of <Emphasis Type="Italic">Ceutorhynchus obstrictus</Emphasis> (Marsham) (Coleoptera: Curculionidae) to olfactory cues associated with novel genotypes developed by <Emphasis Type="Italic">Sinapis alba</Emphasis> L. × <Emphasis Type="Italic">Brassica napus</Emphasis> L.

Many herbivorous insects use olfactory cues for host location. Extracts from Brassica napus L. have been shown to elicit electrophysiological and behavioural responses in the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (syn. C. assimilis (Paykull)) (Coleoptera: Curculionidae). These include volatile products of the hydrolysis of glucosinolates. Here we present results of a laboratory olfactometer study examining the attractiveness of odours from flowering racemes and foliage of Sinapis alba L. (an inappropriate host for larval development), B. napus (an excellent host for larval development) and lines derived from S. alba × B. napus selected from colonization studies to demonstrate resistance or susceptibility. Results of this study indicate differential attraction of C. obstrictus to the odours of resistant and susceptible lines and suggest the role of hydrolysis products of glucosinolates, particularly the attractive effects of 2-phenylethyl isothiocyanate.     

Refolding of porcine growth hormone from inclusion bodies of Escherichia coli

Escherichia. coli cells expressing porcine growth hormone were grown in a batch fermentation process. The expression level was estimated to be nearly 40% of the total cellular protein after 2–3 h of induction with 1?mM isopropyl β-d-thiogalactoside. Porcine growth hormone expressed as inclusion bodies was solubilized in 8 M urea. Refolding conditions following a dilution protocol in the presence of β-mercaptoethanol or using a glutathione pair were tested. Reverse phase-HPLC was applied to distinguish oxidized, misfolded and reduced forms of the hormone. A ratio of reduced to oxidized glutathione equal to 2/1 was chosen to avoid the formation of misfolded forms at high protein concentration.     

The genetic structure of the Lithuanian wolf population

Lithuanian wolves form part of the larger Baltic population, the distribution of which is continuous across the region. In this paper, we evaluate the genetic diversity of the Lithuanian wolf population using mitochondrial DNA analysis and 29 autosomal microsatellite loci. Analysis of the mtDNA control region (647 bp) revealed 5 haplotypes distributed among 29 individuals and high haplotype diversity (0.658). Two haplotypes were distributed across the country, whilst the others were restricted to eastern Lithuania. Analysis of microsatellites revealed high heterozygosity (H_E=0.709) and no evidence for a recent bottleneck. Using detection of first generation migrants, four individuals appeared to assign better with populations genetically differentiated from those resident in Lithuania. These immigrants were males carrying rare mitochondrial haplotypes and were encountered in the eastern part of the country, this indicates that Lithuania is subject to immigration from differentiated populations. Additionally, we did not detect any signs of recent hybridisation with dogs.     

Resource partitioning confirmed by isotopic signatures allows small mammals to share seasonally flooded meadows

Meadows in river deltas are characterized by a high diversity and abundance of small mammals. However, neither their spatial arrangement nor differences in their use of microhabitat can necessarily explain the dense co‐occurrence of sympatric species. We investigated how several small mammal species share a seasonally flooded meadow of limited size, testing predictions (P1) that herbivore, granivore, insectivore, and omnivore species are separated in time (dominant in different years), (P2) that sympatric species undergo isotopic partitioning, and (P3) that there are intraspecific differences in diet. Stable carbon and nitrogen isotope signatures in the hair of seven synantropic shrew, vole, and mice species were used as a proxy for their diet. We found that the three most abundant species in eight of the nine years were from different diet groups. However, based on the number of species in the functional groups, the state of small mammal community was considered unfavored in five out of the nine investigation years. In years with the greatest dominance of Apodemus agrarius, the small mammal community was characterized by decreased diversity and Micromys minutus was either in low abundance or absent. In 2014 and 2016, years of low abundance or absence of M. oeconomus, M. agrestis, and M. glareolus were both recorded in high numbers. Differences in the isotopic signatures of the three most abundant small mammal species in the community were clearly expressed and core areas in the isotopic space were separated, showing their dependence on different dietary resources. Intraspecific dietary separation between young and adult animals was observed only in M. oeconomus. Thus, the high species diversity of small mammals and the formation of their community in this investigated flooded meadow are maintained by isotopic partitioning (segregation in dietary space) and by changes in their number over time (shifting dominance).     

Diet of the fat dormouse (<Emphasis Type="Italic">Glis glis</Emphasis>) on the northern periphery of its distributional range

We studied the seasonal and annual variation in diet composition of the fat dormouse (Glis glis) in Lithuania, a locality situated on the northern periphery of the dormouse range and outside of the range of the European beech (Fagus sylvatica). After emergence from hibernation, dormice fed on oak acorns (from the previous year), inflorescences of various trees, vegetative parts of plants and food of animal origin (birds, their eggs and insects). In June, soft mast and seeds of birches supplemented the dormouse diet, and diet composition was the most diverse during this period. In July, raspberries and fruits of glossy buckthorn constituted the bulk of dormouse diet, but seeds of birches dominated in a specific year. Hard mast (mainly acorns) dominated the diet of G. glis from August until the beginning of hibernation in October. A high prevalence of acorns, comparatively high proportion of birch seeds and low proportion of food of animal origin in the diet, as well as feeding on fruits of glossy buckthorn, are specific features of feeding by G. glis in Lithuania. The diet of G. glis on the northern periphery of its range resembles its diet on the eastern periphery of the range where beech trees are also absent. According to the composition of G. glis diet, feeding conditions in both of these peripheral regions are poorer in comparison to central or southern regions.     

Identification of putative quantitative trait loci associated with a flavonoid related to resistance to cabbage seedpod weevil (Ceutorhynchus obstrictus) in canola derived from an intergeneric cross,Sinapis alba × Brassica napus

Key message

Kaempferol 3- O -sinapoyl-sophoroside 7- O -glucoside was putatively identified as the major component of a characteristic HPLC peak previously correlated with the reduction of cabbage seedpod weevil larval infestation in a novel canola genotype.

Abstract

The cabbage seedpod weevil (Ceutorhynchus obstrictus [Marsham]) (CSPW) is a serious pest of brassicaceous oilseed crops such as canola in both Europe and more recently in North America. At present, the only control strategy against CSPW is the application of insecticides. As an alternative more environmentally-friendly control strategy, we developed novel canola germplasm resistant to weevil attack through introgression of Sinapis alba DNA into Brassica napus by making the wide cross followed by embryo rescue and backcrossing to the B. napus parent. We have previously characterized resistant canola lines by metabolic profiling and were able to correlate reduction of larval infestation to the presence of a characteristic HPLC peak. In this study, we have putatively identified the major component in the peak using mass spectrometry as kaempferol 3-O-sinapoyl-sophoroside 7-O-glucoside (KSSG). We have also identified quantitative trait loci (QTL) associated with this HPLC peak in a mapping population consisting of more than 200 individual doubled haploid (DH) lines derived from a cross between CSW428 (the resistant parent) and SC030686 (the susceptible parent). This QTL accounted for approximately 9.5 % of the phenotypic variation in KSSG content. The observation that only one QTL was identified as surpassing the LOD threshold of 3.0 suggests that both parents may possess the positive alleles for other QTL that have not been detected in our study. This finding also indicates a complex regulatory mechanism for KSSG levels and provides an appropriate explanation for the large transgressive segregation observed in the DH lines of the QTL mapping population.     

Fluff deposition on intertidal sediments: effects on benthic biota, ammonium fluxes and nitrification rates

The effects of fluff deposit on benthic biota,NH₄ ⁺ fluxes and nitrification was studied in thelaboratory using waterlogged and reflooded intertidal sediments fromMarennes-Oléron Bay, France. The fluff deposit was enriched inNH₄ ⁺ compared to underlying sediments, and promotedchanges of the sediment pH, E_h, C:N ratio, C:chla ratio and the NH₄ ⁺ efflux tooverlying water. Statistical analysis showed that pore waterNH₄ ⁺ concentrations were strongly influenced byinteractions between fluff, drying, depth and bioturbation. The fluff depositresulted in anoxia in the top sediments and moved the nitrification zone tosurface layers in fluff. However, the NH₄ ⁺ enrichment influff did not significantly change actual nitrification rates (range 0–1mmol m^–2 d^–1) or potentialnitrification rates (range 3–11 mmolNO₃ ^– m^–2d^–1).     

Human-mediated lineage admixture in an expanding Ponto-Caspian crustacean species <Emphasis Type="Italic">Paramysis lacustris</Emphasis> created a novel genetic stock that now occupies European waters

Identifying the origins and colonization routes of alien species is critical to understanding the mechanisms, consequences and management of invasions. This study aims to demonstrate and explain conflicting genetic signals in a widespread invasive Ponto-Caspian mysid Paramysis lacustris using mitochondrial DNA and microsatellite markers. Native Black Sea populations of P. lacustris are divided into three distinct phylogeographic groups: Danube–Dniester region, coastal Danube lakes, and Dnieper River delta. In the 1950s–1970s the species has been extensively used for relatively well documented transplantations in Eastern Europe. However, the populations in the newly established distribution area do not match any of the known native groups, and their genetic signal does not correspond with the recorded transplantation history. Using Bayesian Approximate Computation we explore alternative scenarios that could explain the unexpected mitochondrial and nuclear signals in the introduced populations. We suggest that reservoir construction and break-up of natural dispersal barriers on the River Dnieper have brought about a novel stock, probably admixed from a previously isolated and unknown “relict” population in the middle Dnieper and the genetically distinct Dnieper delta lineage. Through further intentional transfers this new P. lacustris lineage is now widely present in Eastern Europe and is likely to have new gene and trait combinations. The conflicting mitochondrial-nuclear signal in non-native populations also highlights the importance of using multiple genetic markers when tracing invasion sources and pathways.