Sea trout Salmo trutta in the subarctic: home-bound but large variation in migratory behaviour between and within populations

Anadromous brown trout (sea trout), Salmo trutta, is currently in decline throughout its range, largely due to anthropogenic stressors in freshwater and marine habitats. Acoustic telmetry was utilized to study the marine migration of sea trout post-smolts from three populations in a relatively pristine subarctic fjord system. While at sea, the sea trout spent a substantial part of their time close to their natal river, preferred near shore over pelagic habitats and were strongly surface oriented. Despite a fidelity towards local areas, the sea trout utilized various parts of the fjord system, with maximum dispersion >30 km and total migration distance >300 km. Almost half of the sea trout (44%) migrated between river outlets, indicating that a metapopulation approach may be appropriate when managing neighbouring sea trout populations at high latitudes. Furthermore, the different populations displayed different migratory behaviours in terms of distance migrated, dispersion from origin and the likelihood of leaving their home area. This variation in migratory behaviour is likely influenced by spatiotemporal differences in habitat quality between sites, indicating that local habitat variations may promote population-specific behavioural responses even in relatively confined fjord systems.     

Economic Recession and Emergence of an HIV-1 Outbreak among Drug Injectors in Athens Metropolitan Area: A Longitudinal Study

Background

During 2011, a dramatic increase (1600%) of reported HIV-1 infections among injecting drug users (IDUs) was noted in Athens, Greece. We herein assess the potential causal pathways associated with this outbreak.

Methods

Our study employed high resolution HIV-1 phylogenetic and phylogeographic analyses. We examined also longitudinal data of ecological variables such as the annual growth of gross domestic product (GDP) of Greece in association with HIV-1 and HCV sentinel prevalence in IDUs, unemployment and homelessness rates and HIV transmission networks in Athens IDUs before and during economic recession (2008–2012).

Results

IDU isolates sampled in 2011 and 2012 suggested transmission networks in 94.6% and 92.7% of the cases in striking contrast with the sporadic networking (5%) during 1998–2009. The geographic origin of most HIV-1 isolates was consistent with the recently documented migratory waves in Greece. The decline in GDP was inversely correlated with annual prevalence rates of HIV and HCV and with unemployment and homelessness rates in IDUs (all p<0.001). The slope of anti-HCV prevalence in the sentinel populations of IDUs and in “new” drug injectors was found 120 and 1.9-fold (p = 0.007, p = 0.08 respectively) higher in 2008–2012 (economic recession) compared with 2002–2006. The median (25th, 75th) size of transmission networks were 34 (12, 58) and 2 (2, 2) (p = 0.057) in 2008–2012 and 1998–2007, respectively. The coverage of harm reduction services was low throughout the study period.

Conclusions

Scaling-up harm reduction services and addressing social and structural factors related to the current economic crisis should be urgently considered in environments where HIV-1 outbreaks may occur.     

The novel GrCEP12 peptide from the plant-parasitic nematode Globodera rostochiensis suppresses flg22-mediated PTI

The potato cyst nematode Globodera rostochiensis is a biotrophic pathogen that secretes effector proteins into host root cells to promote successful plant parasitism. In addition to the role in generating within root tissue the feeding cells essential for nematode development,¹ nematode secreted effectors are becoming recognized as suppressors of plant immunity.^2-4 Recently we reported that the effector ubiquitin carboxyl extension protein (GrUBCEP12) from G. rostochiensis is processed into free ubiquitin and a 12-amino acid GrCEP12 peptide in planta. Transgenic potato lines overexpressing the derived GrCEP12 peptide showed increased susceptibility to G. rostochiensis and to an unrelated bacterial pathogen Streptomyces scabies, suggesting that GrCEP12 has a role in suppressing host basal defense or possibly pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) during the parasitic interaction.³ To determine if GrCEP12 functions as a PTI suppressor we evaluated whether GrCEP12 suppresses flg22-induced PTI responses in Nicotiana benthamiana. Interestingly, we found that transient expression of GrCEP12 in N. benthamiana leaves suppressed reactive oxygen species (ROS) production and the induction of two PTI marker genes triggered by the bacterial PAMP flg22, providing direct evidence that GrCEP12 indeed has an activity in PTI suppression.     

The relationship between anatomy and photosynthetic performance of heterobaric leaves

Heterobaric leaves show heterogeneous pigmentation due to the occurrence of a network of transparent areas that are created from the bundle sheaths extensions (BSEs). Image analysis showed that the percentage of photosynthetically active leaf area (Ap) of the heterobaric leaves of 31 plant species was species dependent, ranging from 91% in Malva sylvestris to only 48% in Gynerium sp. Although a significant portion of the leaf surface does not correspond to photosynthetic tissue, the photosynthetic capacity of these leaves, expressed per unit of projected area (Pmax), was not considerably affected by the size of their transparent leaf area (At). This means that the photosynthetic capacity expressed per Ap (P*max) should increase with At. Moreover, the expression of P*max could be allowing the interpretation of the photosynthetic performance in relation to some critical anatomical traits. The P*max, irrespective of plant species, correlated with the specific leaf transparent volume (lambda(t)), as well as with the transparent leaf area complexity factor ((CF)A(t)), parameters indicating the volume per unit leaf area and length/density of the transparent tissues, respectively. Moreover, both parameters increased exponentially with leaf thickness, suggesting an essential functional role of BSEs mainly in thick leaves. The results of the present study suggest that although the Ap of an heterobaric leaf is reduced, the photosynthetic performance of each areole is increased, possibly due to the light transferring capacity of BSEs. This mechanism may allow a significant increase in leaf thickness and a consequent increase of the photosynthetic capacity per unit (projected) area, offering adaptive advantages in xerothermic environments.     

A severe form of human combined immunodeficiency due to mutations in DNA ligase IV

DNA ligase IV (LigIV) deficiency was identified as the molecular basis for a severe form of combined immunodeficiency in two microcephalic siblings with cellular radiosensitivity. In one patient the diagnosis was made directly after birth, allowing analysis of the role of LigIV in the development of specific immune cells. Absolute numbers of B cells were reduced 100-fold and alphabeta T cells 10-fold, whereas gammadelta T cells were normal. Spectratyping of all three cell populations showed a diverse repertoire, but sequencing of IgH V(D)J junctions revealed shorter CDR3 regions due to more extensive nucleotide deletions among D and J elements and fewer N nucleotide insertions. Clonal restriction of IgG-expressing, but not IgM-expressing, B cells and the lack of primary and secondary lymph node follicles indicated impaired class switch recombination. Observations in the older sibling showed that this rudimentary immune system was able to mount specific responses to infection. However, partial Ab responses and extensive amplification of gammadelta T cells could not prevent a life-threatening course of viral and bacterial infections, the development of an EBV-induced lymphoma, and immune dysregulation reflected by severe autoimmune cytopenia. Impaired generation of immune diversity under conditions of limited LigIV activity can cause a human SCID variant with a characteristic immunological phenotype.     

Use of Fibrates and Cancer Risk: A Systematic Review and Meta-Analysis of 17 Long-Term Randomized Placebo-Controlled Trials

Background

Fibrates comprise a class of well-established antilipidemic agents that significantly reduce cardiovascular events. Given the concerns of cancer with fibrate therapy, we undertook a systematic review and meta-analysis to investigate the effects of fibrates on cancer outcomes.

Methods

We systematically searched Medline, Scopus, SCI Expanded, and the Cochrane Library for studies published up to 2012. We included randomized controlled trials (RCTs) that evaluated a fibrate therapy compared with placebo, had a minimum duration of two years, and reported data on the incidence of and/or deaths from cancer during the trial. Reviews of each study were performed and the relative data were abstracted. Pooled relative risk estimates (RR) and 95% confidence intervals (CIs) were calculated using the inverse variance weighted approach. Subgroup, sensitivity and meta-regression analyses were also conducted.

Results

Seventeen RCTs, involving 44,929 participants with an average follow-up of 5.2 years, contributed to the analysis. The degree of variability between trials was consistent with what would be expected to occur by chance alone. The quantitative synthesis of data retrieved from the RCTs was not indicative of a fibrate effect on cancer incidence (780 [fibrate] vs 814 [control]; RR = 1.02, 95% CI 0.92–1.12) or cancer death (385 [fibrate] vs 377 [control]; RR = 1.06, 95% CI: 0.92–1.22). When the analysis was restricted to major RCTs, the results did not substantially change. Similarly, we found no evidence of differential effects by length of follow-up or type of fibrate. Insignificant results were also obtained for the role of fibrates in cancers of the respiratory tract, breast, colon, gastrointestinal tract, prostate, genitourinary tract, or in melanoma.

Conclusion

Our findings demonstrate that fibrates have a neutral effect on cancer outcomes. However, it is important to continue monitoring their long-term safety profiles.     

The effects of UV-B radiation on European heathland species

The effects of enhanced UV-B radiation on three examples of European shrub-dominated vegetation were studied in situ. The experiments were in High Arctic Greenland, northern Sweden and Greece, and at all sites investigated the interaction of enhanced UV-B radiation (simulating a 15% reduction in the ozone layer) with artificially increased precipitation. The Swedish experiment also involved a study of the interaction between enhanced UV-B radiation and elevated CO₂ (600 ppm). These field studies were supported by an outdoor controlled environment study in the United Kingdom involving modulated enhancement of UV-B radiation in combination with elevated CO₂ (700 ppm). Effects of the treatments on plant growth, morphology, phenology and physiology were measured. The effects observed were species specific, and included both positive and negative responses to the treatments. In general the negative responses to UV-B treatments of up to three growing seasons were small, but included reductions in shoot growth and premature leaf senescence. Positive responses included a marked increase in flowering in some species and a stimulation of some photosynthetic processes. UV-B treatment enhanced the drought tolerance of Pinus pinea and Pinus halepensis by increasing leaf cuticle thickness. In general, there were few interactions between the elevated CO₂ and enhanced UV-B treatments. There was evidence to suggest that although the negative responses to the treatments were small, damage may be increasing with time in some long-lived woody perennials. There was also evidence in the third year of treatments for effects of UV-B on insect herbivory in Vaccinium species. The experiments point to the necessity for long-term field investigations to predict the likely ecological consequences of increasing UV-B radiation.     

Beneficial effects of enhanced UV-B radiation under field conditions: improvement of needle water relations and survival capacity of Pinus pinea L. seedlings during the dry Mediterranean summer

The possible mechanism(s) by which supplemental UV-B radiation alleviates the adverse effects of summer drought in Mediterranean pines (Petropoulou et al. 1995) were investigated with seedlings of Pinus pinea. Plants received ambient or ambient plus supplemental UV-B radiation (biologically equivalent to a 15% ozone depletion over Patras, 38.3° N, 29.1° E) and natural precipitation or additional irrigation. Treatments started on 1 February, 1994 and lasted up to the end of the dry period (29 September). In well-watered plants, UV-B radiation had no influence on photosystem II photochemical efficiency and biomass accumulation. Water stressed plants suffered from needle loss and reduced photosystem II photochemical efficiency during the summer. These symptoms, however, were less pronounced in plants receiving supplemental UV-B radiation, resulting in higher total biomass at plant harvest. Laboratory tests showed that enhanced UV-B radiation did not improve the tolerance of photosystem II against drought, high light, high temperature and oxidative stress. Enhanced UV-B radiation, however, improved the water economy of water stressed plants, as judged by measurements of needle relative water content. In addition, it caused an almost two-fold increase of cuticle thickness. No such UV-B radiation effects were observed in well-watered pines. The results indicate that the combination of water stress and UV-B radiation may trigger specific responses, enabling the plants to avoid excessive water loss and, thereby, maintain a more efficient photosynthetic apparatus during the summer. The extent of this apparently positive UV-B radiation effect would depend on the amount of summer precipitation. Abbreviations: DW – dry weight, F_v/F_m – ratio of variable to maximum fluorescence, A ₃₀₀ – absorbance at 300 nm, PAR – photosynthetically active radiation, PS II – photosystem II, RWC – relative water content, TCA – trichloroacetic acid, UV-B_BE – biologically effective ultraviolet-B radiation