Changing expression of vertebrate immunity genes in an anthropogenic environment: a controlled experiment

Background: The effect of anthropogenic environments on the function of the vertebrate immune system is a problem of general importance. For example, it relates to the increasing rates of immunologically-based disease in modern human populations and to the desirability of identifying optimal immune function in domesticated animals. Despite this importance, our present understanding is compromised by a deficit of experimental studies that make adequately matched comparisons between wild and captive vertebrates. Results: We transferred post-larval fishes (three-spined sticklebacks), collected in the wild, to an anthropogenic (captive) environment. We then monitored, over 11 months, how the systemic expression of immunity genes changed in comparison to cohort-matched wild individuals in the originator population (total n = 299). We found that a range of innate (lyz, defbl2, il1r-like, tbk1)and adaptive (cd8a, igmh) immunity genes were up-regulated in captivity, accompanied by an increase in expression of the antioxidant enzyme, gpx4a. For some genes previously known to show seasonality in the wild, this appeared to be reduced in captive fishes. Captive fishes tended to express immunity genes, including igzh, foxp3b, lyz, defbl2, and il1r-like, more variably. Furthermore, although gene co-expression patterns (analyzed through gene-by-gene correlations and mutual information theory based networks) shared common structure in wild and captive fishes, there was also significant divergence. For one gene in particular, defbl2, high expression was associated with adverse health outcomes in captive fishes. Conclusion: Taken together, these results demonstrate widespread regulatory changes in the immune system in captive populations, and that the expression of immunity genes is more constrained in the wild. An increase in constitutive systemic immune activity, such as we observed here, may alter the risk of immunopathology and contribute to variance in health in vertebrate populations exposed to anthropogenic environments

Exploiting bacterial DNA gyrase as a drug target: current state and perspectives

DNA gyrase is a type II topoisomerase that can introduce negative supercoils into DNA at the expense of ATP hydrolysis. It is essential in all bacteria but absent from higher eukaryotes, making it an attractive target for antibacterials. The fluoroquinolones are examples of very successful gyrase-targeted drugs, but the rise in bacterial resistance to these agents means that we not only need to seek new compounds, but also new modes of inhibition of this enzyme. We review known gyrase-specific drugs and toxins and assess the prospects for developing new antibacterials targeted to this enzyme

Iron isotope fractionation at the core–mantle boundary by thermodiffusion

The D” layer at the base of the Earth’s mantle exhibits anomalous seismic properties, which are attributed to heat loss from and chemical interaction with the underlying molten Fe-rich outer core. Here we show that mass transfer due to temperature variations within the D” layer could lead to resolvable fractionation of iron isotopes. We constrain the degree of isotope fractionation by experiments on core-forming Fe alloy liquids at 2100–2300 K and 2 GPa, which demonstrate that heavy Fe isotopes preferentially migrate towards lower temperature and vice versa. We find that this isotope fractionation occurs rapidly due to the high mobility of iron, which reaches 0.013 ± 0.002‰ (2σ) per degree per amu at steady state. Numerical simulations of mantle convection capturing the evolution of a basal thermal boundary layer show that iron isotope fractionation immediately above the core–mantle boundary can reach measurable levels on geologic timescales and that plumes can entrain this fractionated material into the convecting mantle. We suggest that such a process may contribute to the heavy Fe isotope composition of the upper mantle inferred from mantle melts (basalts) and residues (peridotites) relative to chondrites. That being the case, non-traditional stable isotope systems such as Fe may constrain the interactions between the core and mantle

β − decay of 65 Mn to65 Fe

The low-energy structure of 65Fe has been studied by means ofγand fast-timing spectroscopy at the ISOLDE facility, CERN. A level scheme of 65Fe populated following the β− decay of 65Mn was established for the first time. It includes 41 levels and 85 transitions. The excitation energy of the β-decaying isomer in 65Fe has been precisely determined at 393.7(2) keV. Theβ-delayed neutron emission branch was measured asPn=7.9(12)%, which cannot be reconciled with the previously reported value of 21.0(5)%. Fourγrays and four excited states in 64Fe were identified as being populated following theβ-ndecay. Four lifetimes and five lifetime limits in the subnanosecond range have been measured using the advanced time-delayedβγγ(t) method. The level scheme is compared with shell-model calculations. Tentative spin and parity assignments are proposed based on the observed transition rates, the calculations, and the systematics of the region.status: publishe

Search for shape-coexisting 0+ states in 66Ni from lifetime measurements

The lifetime of the 0+3 state in 66Ni, two neutrons below the N=40 subshell gap, has been measured. The transition B(E2;0+3→2+1) is one of the most hindered E2 transitions in the Ni isotopic chain and it implies that, unlike 68Ni, there is a spherical structure at low excitation energy. We have performed extensive shell-model calculations that correctly predict this result, obtaining a spherical 0+ state at the correct energy and with an extremely low B(E2;0+3→2+1) value.status: publishe

Properties of low-lying states in 65Co from lifetime measurements

© 2019 American Physical Society. The low-energy structure of Co65 was studied by means of γ-and fast-timing spectroscopy at the ISOLDE/CERN facility. The known level scheme of Co65 populated following the β-decay of Fe65 was expanded. The experimental results were compared with large-scale shell-model calculations. The measured long lifetime of the (1/21-) level confirms its nature as a highly collective state with proton excitations across the Z=28 gap and neutrons across the N=40 subshell.status: publishe