Leukotoxic Activity of Aggregatibacter actinomycetemcomitans and Periodontal Attachment Loss

Aggregatibacter actinomycetemcomitans is a Gram-negative periodontitis-associated bacterium that expresses a toxin that selectively affects leukocytes. This leukotoxin is encoded by an operon belonging to the core genome of this bacterial species. Variations in the expression of the leukotoxin have been reported, and a well-characterized specific clonal type (JP2) of this bacterium with enhanced leukotoxin expression has been isolated. In particular, the presence of the JP2 genotype significantly increases the risk for the progression of periodontal attachment loss (AL). Based on these findings we hypothesized that variations in the leukotoxicity are linked to disease progression in infected individuals. In the present study, the leukotoxicity of 239 clinical isolates of A. actinomycetemcomitans was analysed with different bioassays, and the genetic peculiarities of the isolates were related to their leukotoxicity based on examination with molecular techniques. The periodontal status of the individuals sampled for the presence of A. actinomycetemcomitans was examined longitudinally, and the importance of the observed variations in leukotoxicity was evaluated in relation to disease progression. Our data show that high leukotoxicity correlates with an enhanced risk for the progression of AL. The JP2 genotype isolates were all highly leukotoxic, while the isolates with an intact leukotoxin promoter (non-JP2 genotypes) showed substantial variation in leukotoxicity. Genetic characterization of the non-JP2 genotype isolates indicated the presence of highly leukotoxic genotypes of serotype b with similarities to the JP2 genotype. Based on these results, we conclude that A. actinomycetemcomitans harbours other highly virulent genotypes besides the previously described JP2 genotype. In addition, the results from the present study further highlight the importance of the leukotoxin as a key virulence factor in aggressive forms of periodontitis.     

Impact of sequential exposure of <Emphasis Type="Italic">Beauveria bassiana</Emphasis> and imidacloprid against susceptible and resistant strains of <Emphasis Type="Italic">Musca domestica</Emphasis>

Insecticide resistance in the housefly Musca domestica is hampering pest management. However, entomopathogens, possibly in combination with insecticides, may have control potential against resistant houseflies. This study investigates the combination of the entomopathogenic fungus Beauveria bassiana and the neonicotinoid insecticide, imidacloprid against a susceptible and a resistant housefly strain, respectively under laboratory conditions. The fungus and insecticide were tested alone and in combinations at LC₃₀. Significant and synergistic interactions between B. bassiana and imidacloprid were observed with increased mortality rates of the combined treatment as compared to individual treatment in housefly strains 772a (susceptible) and 766b (resistant). Significant differences in the GST and P450 activities for both strains were found. Female 766b flies caused 15- to 237-fold increases in gene expression of xenobiotic response genes for B. bassiana and 23- to 120-fold changes for imidacloprid. The combination of B. bassiana and imidacloprid caused significant synergistic interaction when applied against two housefly strains irrespective of order of application. The effect was highest when the insecticide was applied first. The resistant housefly strain had elevated detoxification enzymes and higher expression of detoxification genes, but showed the same level of susceptibility to the combined fungus/insecticide treatment as the susceptible strain.     

Population genetic structure after 125 years of stocking in sea trout (<Emphasis Type="Italic">Salmo trutta</Emphasis> L.)

Stocking can be an effective management and conservation tool, but it also carries the danger of eroding natural population structure, introducing non-native strains and reducing genetic diversity. Sea trout, the anadromous form of the brown trout (Salmo trutta), is a highly targeted species that is often managed by stocking. Here, we assess the present-day population genetic structure of sea trout in a backdrop of 125 years of stocking in Northern Germany. The study area is characterized by short distances between the Baltic and North Sea river watersheds, historic use of fish from both watersheds for stocking, and the creation of a potential migration corridor between the Baltic and North Sea with the opening of the Kiel Canal 120 years ago. A survey of 24 river systems with 180 SNPs indicates that moderate but highly significant population genetic structure has persisted both within and between the Baltic and North Sea. This genetic structure is characterized by (i) heterogeneous patterns of admixture between the Baltic and North Sea that do not correlate with distance from the Kiel Canal and are therefore likely due to historic stocking practises, (ii) genetic isolation by distance in the Baltic Sea at a spatial scale of <?200 km that is consistent with the homing behaviour of sea trout, and (iii) at least one genetically distinct Baltic Sea river system. In light of these results, we recommend keeping fish of North Sea and Baltic Sea origin separate for stocking, and restricting Baltic Sea translocations to neighbouring river systems.     

Hidden biodiversity in the Arctic – a study of soil seed banks at Disko Island,Qeqertarsuaq, West Greenland

Seed dispersal is a key process in plant community dynamics, and soil seed banks represent seed dispersal in time rather than in space. Despite their potential importance, seed bank dynamics in the Arctic are poorly understood. We investigated soil seed banks and corresponding plant community composition in three contrasting vegetation types in West Greenland, viz. dwarf shrub heaths, herb slopes and fell‐fields. Through germination testing, 31 species were documented in soil seed banks. All of these were herbaceous, while no dwarf‐shrub species, which represents the dominating growth form in the above‐ground vegetation, were emerging from the seed bank. Consequently, across vegetation types, the lowest similarity between seed bank and above‐ground vegetation was found in dwarf shrub heath. Nine plant species were exclusively found in seed bank, all of which were non‐clonal forbs. Seed bank size (total number of seeds) and species richness seemed to increase with the level of natural disturbance. Additionally, we examined the effect of different experimental light and temperature conditions on the quantity and diversity of germinating seeds. The difference in diversity in vegetation and seed bank at the species level will impact population dynamics, regeneration of vegetation after disturbances and its potential to respond to climate change.     

Sponge communities of the Antarctic Peninsula: influence of environmental variables on species composition and richness

Sponge communities on the Antarctic continental shelf currently represent one of the most extensive sponge grounds in the world, and all sponge classes are known to occur in the Southern Ocean. Main objectives of this study conducted at the tip of the Antarctic Peninsula were (1) to identify all sampled sponges and (2) to investigate whether the species composition and species richness of Southern Ocean sponge communities in the area of the Antarctic Peninsula are significantly influenced by environmental variables. The studied material originated from 25 AGT catches and was sampled during the expedition ANT-XXIX/3 of RV Polarstern. Samples were collected in three large-scale areas in the vicinity of the Antarctic Peninsula: Bransfield Strait, Drake Passage and Weddell Sea. The following six environmental variables were measured from bottom water samples (except for sea-ice cover): depth (m), light transmission (%), oxygen (µmol/kg), salinity, sea-ice cover (%) and temperature (°C). Two hundred and sixty-three sponge samples were analyzed, and 81 species of 33 genera from all Porifera classes (Calcarea, Demospongiae, Hexactinellida and Homoscleromorpha) were identified. Total numbers of sponge species per sample station ranged from 1 to 29. A detrended correspondence analysis and a backward-stepwise model selection were performed to check whether species composition and richness were significantly influenced by environmental variables. The analyses revealed that none of the measured environmental variables significantly influenced species composition but that species richness was significantly influenced by (1) temperature and (2) the combination of temperature and depth. Results of this study are of crucial importance for development, performance and assessment of future protection strategies in case of ongoing climatic changes at the Antarctic Peninsula.     

Screening of the Antarctic marine sponges (Porifera) as a source of bioactive compounds

Sponges (Porifera) currently represent one of the richest sources of natural products and account for almost half of the pharmacologically active compounds of marine origin. However, to date very little is known about the pharmacological potential of the sponges from polar regions. In this work we report on screening of ethanolic extracts from 24 Antarctic marine sponges for different biological activities. The extracts were tested for cytotoxic effects against normal and transformed cell lines, red blood cells, and algae, for modulation of the activities of selected physiologically important enzymes (acetylcholinesterase, butyrylcholinesterase, and α-amylase), and for inhibition of growth of pathogenic and ecologically relevant bacteria and fungi. An extract from Tedania (Tedaniopsis) oxeata was selectively cytotoxic against the cancer cell lines and showed growth inhibition of all of the tested ecologically relevant and potentially pathogenic fungal isolates. The sponge extracts from Isodictya erinacea and Kirkpatrickia variolosa inhibited the activities of the cholinesterase enzymes, while the sponge extracts from Isodictya lankesteri and Inflatella belli reduced the activity of α-amylase. Several sponge extracts inhibited the growth of multiresistant pathogenic bacterial isolates of different origins, including extended-spectrum beta-lactamase and carbapenem-resistant strains, while sponge extracts from K. variolosa and Myxilla (Myxilla) mollis were active against a human methicillin-resistant Staphylococcus aureus strain. We conclude that Antarctic marine sponges represent a valuable source of biologically active compounds with pharmacological potential.     

Non‐parallel divergence across freshwater and marine three‐spined stickleback Gasterosteus aculeatus populations

This work investigated whether multiple freshwater populations of three‐spined stickleback Gasterosteus aculeatus in different freshwater catchments in the Jutland Peninsula, Denmark, derived from the same marine populations show repeated adaptive responses. A total of 327 G. aculeatus collected at 13 sampling locations were screened for genetic variation using a combination of 70 genes putatively under selection and 26 neutral genes along with a marker linked to the ectodysplasin gene (eda), which is strongly correlated with plate armour morphs in the species. A highly significant genetic differentiation was found that was higher among different freshwater samples than between marine–freshwater samples. Tests for selection between marine and freshwater populations showed a very low degree of parallelism and no single nucleotide polymorphism was detected as outlier in all freshwater–marine pairwise comparisons, including the eda. This suggests that G. aculeatus is not necessarily the prime example of parallel local adaptation suggested in much of the literature and that important exceptions exist (i.e. the Jutland Peninsula). While marine populations in the results described here showed a high phenotype–genotype correlation at eda, a low association was found for most of the freshwater populations. The most extreme case was found in the freshwater Lake Hald where all low‐plated phenotypes were either homozygotes for the allele supposed to be associated with completely plated morphs or heterozygotes, but none were homozygotes for the putative low‐plated allele. Re‐examination of data from seven G. aculeatus studies agrees in showing a high but partial association between phenotype–genotype at eda in G. aculeatus freshwater populations and that mismatches occur everywhere in the European regions studied (higher in some areas, i.e. Denmark). This is independent of the eda marker used.     

Infections in temporal proximity to HPV vaccination and adverse effects following vaccination in Denmark: A nationwide register-based cohort study and case-crossover analysis

BackgroundPublic trust in the human papilloma virus (HPV) vaccination programme has been challenged by reports of potential severe adverse effects. The reported adverse symptoms were heterogeneous and overlapping with those characterised as chronic fatigue syndrome (CFS) and have been described as CFS-like symptoms. Evidence suggests that CFS is often precipitated by an infection. The aim of the study was to examine if an infection in temporal proximity to HPV vaccination is a risk factor for suspected adverse effects following HPV vaccination.Methods and findingsThe study was a nationwide register-based cohort study and case-crossover analysis. The study population consisted of all HPV vaccinated females living in Denmark, born between 1974 and 2006, and vaccinated between January 1, 2006 and December 31, 2017. The exposure was any infection in the period ± 1 month around time of first HPV vaccination and was defined as (1) hospital-treated infection; (2) redemption of anti-infective medication; or (3) having a rapid streptococcal test done at the general practitioner. The outcome was referral to a specialised hospital setting (5 national HPV centres opened June 1, 2015) due to suspected adverse effects following HPV vaccination. Multivariable logistic regression was used to estimate the association between infection and later HPV centre referral. The participants were 600,400 HPV-vaccinated females aged 11 to 44 years. Of these, 48,361 (9.7%) females had a hospital-treated infection, redeemed anti-infective medication, or had a rapid streptococcal test ± 1 month around time of first HPV vaccination. A total of 1,755 (0.3%) females were referred to an HPV centre. Having a hospital-treated infection in temporal proximity to vaccination was associated with significantly elevated risk of later referral to an HPV centre (odds ratio (OR) 2.75, 95% confidence interval (CI) 1.72 to 4.40; P < 0.001). Increased risk was also observed among females who redeemed anti-infective medication (OR 1.56, 95% CI 1.33 to 1.83; P < 0.001) or had a rapid streptococcal test (OR 1.45, 95% CI 1.10 to 1.93; P = 0.010). Results from a case-crossover analysis, which was performed to adjust for potential unmeasured confounding, supported the findings. A key limitation of the study is that the HPV centres did not open until June 1, 2015, which may have led to an underestimation of the risk of suspected adverse effects, but stratified analyses by year of vaccination yielded similar results.ConclusionsTreated infection in temporal proximity to HPV vaccination is associated with increased risk for later referral with suspected adverse vaccine effects. Thus, the infection could potentially be a trigger of the CFS-like symptoms in a subset of the referred females. To our knowledge, the study is the first to investigate the role of infection in the development of suspected adverse effects after HPV vaccination and replication of these findings are needed in other studies.

Lene Wulff Krogsgaard and co-workers study temporal associations between infections and HPV vaccination.