Cyto‐nuclear discordance suggests complex evolutionary history in the cave‐dwelling salamander,Eurycea lucifuga

Our understanding of the evolutionary history and ecology of cave‐associated species has been driven historically by studies of morphologically adapted cave‐restricted species. Our understanding of the evolutionary history and ecology of nonrestricted cave species, troglophiles, is limited to a few studies, which present differing accounts of troglophiles’ relationship with the cave habitat, and its impact on population dynamics. Here, we used phylogenetics, demographic statistics, and population genetic methods to study lineage divergence, dates of divergence, and population structure in the Cave Salamander, Eurycea lucifuga, across its range. In order to perform these analyses, we sampled 233 individuals from 49 populations, using sequence data from three gene loci as well as genotyping data from 19 newly designed microsatellite markers. We find, as in many other species studied in a phylogeographic context, discordance between patterns inferred from mitochondrial relationships and those inferred by nuclear markers indicating a complicated evolutionary history in this species. Our results suggest Pleistocene‐based divergence among three main lineages within E. lucifuga corresponding to the western, central, and eastern regions of the range, similar to patterns seen in species separated in multiple refugia during climatic shifts. The conflict between mitochondrial and nuclear patterns is consistent with what we would expect from secondary contact between regional populations following expansion from multiple refugia.     

The immunoglobulin of the brown trout, Salmo trutta and its concentration in the serum of antigen-stimulated and non-stimulated fish

Immunoglobulin production in the primary and secondary immune response of brown trout to keyhole limpet haemocyanin has been investigated including the effect of dose size, route and number of injections, and the use of adjuvant. Antibody activity was found in the first fraction from Sephadex G200 and in the second from Sepharose 6B. Trout immunoglobulin had β₂—Γ₁ electrophoretic mobility, and S_app of 16·7 and an approximate molecular weight of 670 000 daltons. It was sensitive to dithiothreitol and stable at 56°C for 30 min. Immunoglobulin concentrations were measured by single radial immunodiffusion with a specific rabbit antiserum. Sera from non-injected trout had a mean immunoglobulin level of 7·3 ± 0·3 mg ml⁻¹ which accounted for 10% of the total serum protein. Phosphate buffered saline-injected controls contained 6·7 ± 0·2. In fish given a single injection the mean concentration ranged from 7·5 to 12·9 and in those given more than one injection from 12·6 to 16·8. The use of adjuvant resulted in higher immunoglobulin concentrations. Neither dose nor route had any significant effect on the primary response. However, in the secondary response the intramuscular route resulted in significantly increased immunoglobulin production.     

Re-engineering Escherichia coli for ethanol production

A lactate producing derivative of Escherichia coli KO11, strain SZ110, was re-engineered for ethanol production by deleting genes encoding all fermentative routes for NADH and randomly inserting a promoterless mini-Tn5 cassette (transpososome) containing the complete Zymomonas mobilis ethanol pathway (pdc, adhA, and adhB) into the chromosome. By selecting for fermentative growth in mineral salts medium containing xylose, a highly productive strain was isolated in which the ethanol cassette had been integrated behind the rrlE promoter, designated strain LY160 (KO11, Δfrd::celY _Ec ΔadhE ΔldhA, ΔackA lacA::casAB _Ko rrlE::(pdc _Zm -adhA _Zm -adhB _Zm -FRT-rrlE) pflB ⁺ ). This strain fermented 9% (w/v) xylose to 4% (w/v) ethanol in 48 h in mineral salts medium, nearly equal to the performance of KO11 with Luria broth.     

Niche diversification follows key innovation in Antarctic fish radiation

Antarctic notothenioid fishes provide a fascinating evolutionary laboratory for the study of adaptive radiation, as their diversification is linked to both isolation in an extreme environment and a key innovation that allows them to exploit it. In this issue of Molecular Ecology, Rutschmann et al. (2011) evaluate how dietary niche differences have evolved in notothenioids: rarely, or repeatedly in multiple lineages. The authors use stable isotopes to measure species’ use of benthic vs. pelagic resources and map resource use onto a molecular phylogeny. Their findings indicate that pelagic diets have evolved in multiple lineages in at least two families, indicating that dietary niche diversification has occurred repeatedly and in parallel.     

When should we expect early bursts of trait evolution in comparative data? Predictions from an evolutionary food web model

Conceptual models of adaptive radiation predict that competitive interactions among species will result in an early burst of speciation and trait evolution followed by a slowdown in diversification rates. Empirical studies often show early accumulation of lineages in phylogenetic trees, but usually fail to detect early bursts of phenotypic evolution. We use an evolutionary simulation model to assemble food webs through adaptive radiation, and examine patterns in the resulting phylogenetic trees and species' traits (body size and trophic position). We find that when foraging trade-offs result in food webs where all species occupy integer trophic levels, lineage diversity and trait disparity are concentrated early in the tree, consistent with the early burst model. In contrast, in food webs in which many omnivorous species feed at multiple trophic levels, high levels of turnover of species' identities and traits tend to eliminate the early burst signal. These results suggest testable predictions about how the niche structure of ecological communities may be reflected by macroevolutionary patterns.     

A blueberry-enriched diet attenuates nephropathy in a rat model of hypertension via reduction in oxidative stress

Objective and Background

To assess renoprotective effects of a blueberry-enriched diet in a rat model of hypertension. Oxidative stress (OS) appears to be involved in the development of hypertension and related renal injury. Pharmacological antioxidants can attenuate hypertension and hypertension-induced renal injury; however, attention has shifted recently to the therapeutic potential of natural products as antioxidants. Blueberries (BB) have among the highest antioxidant capacities of fruits and vegetables.

Methods and Results

Male spontaneously hypertensive rats received a BB-enriched diet (2% w/w) or an isocaloric control diet for 6 or 12 weeks or 2 days. Compared to controls, rats fed BB-enriched diet for 6 or 12 weeks exhibited lower blood pressure, improved glomerular filtration rate, and decreased renovascular resistance. As measured by electron paramagnetic resonance spectroscopy, significant decreases in total reactive oxygen species (ROS), peroxynitrite, and superoxide production rates were observed in kidney tissues in rats on long-term dietary treatment, consistent with reduced pathology and improved function. Additionally, measures of antioxidant status improved; specifically, renal glutathione and catalase activities increased markedly. Contrasted to these observations indicating reduced OS in the BB group after long-term feeding, similar measurements made in rats fed the same diet for only 2 days yielded evidence of increased OS; specifically, significant increases in total ROS, peroxynitrite, and superoxide production rates in all tissues (kidney, brain, and liver) assayed in BB-fed rats. These results were evidence of “hormesis” during brief exposure, which dissipated with time as indicated by enhanced levels of catalase in heart and liver of BB group.

Conclusion

Long-term feeding of BB-enriched diet lowered blood pressure, preserved renal hemodynamics, and improved redox status in kidneys of hypertensive rats and concomitantly demonstrated the potential to delay or attenuate development of hypertension-induced renal injury, and these effects appear to be mediated by a short-term hormetic response.     

The serine protease Omi/HtrA2 regulates apoptosis by binding XIAP through a reaper-like motif

The inhibitor-of-apoptosis proteins (IAPs) play a critical role in the regulation of apoptosis by binding and inhibiting caspases. Reaper family proteins and Smac/DIABLO use a conserved amino-terminal sequence to bind to IAPs in flies and mammals, respectively, blocking their ability to inhibit caspases and thus promoting apoptosis. Here we have identified the serine protease Omi/HtrA2 as a second mammalian XIAP-binding protein with a Reaper-like motif. This protease autoprocesses to form a protein with amino-terminal homology to Smac/DIABLO and Reaper family proteins. Full-length Omi/HtrA2 is localized to mitochondria but fails to interact with XIAP. Mitochondria also contain processed Omi/HtrA2, which, following apoptotic insult, translocates to the cytosol, where it interacts with XIAP. Overexpression of Omi/HtrA2 sensitizes cells to apoptosis, and its removal by RNA interference reduces cell death. Omi/HtrA2 thus extends the set of mammalian proteins with Reaper-like function that are released from the mitochondria during apoptosis.     

Detection of fatty acids from intact microorganisms by molecular beam static secondary ion mass spectrometry

We report the use of a surface analysis approach, static secondary ion mass spectrometry (SIMS) equipped with a molecular (ReO(4)(-)) ion primary beam, to analyze the surface of intact microbial cells. SIMS spectra of 28 microorganisms were compared to fatty acid profiles determined by gas chromatographic analysis of transesterfied fatty acids extracted from the same organisms. The results indicate that surface bombardment using the molecular primary beam cleaved the ester linkage characteristic of bacteria at the glycerophosphate backbone of the phospholipid components of the cell membrane. This cleavage enables direct detection of the fatty acid conjugate base of intact microorganisms by static SIMS. The limit of detection for this approach is approximately 10(7) bacterial cells/cm(2). Multivariate statistical methods were applied in a graded approach to the SIMS microbial data. The results showed that the full data set could initially be statistically grouped based upon major differences in biochemical composition of the cell wall. The gram-positive bacteria were further statistically analyzed, followed by final analysis of a specific bacterial genus that was successfully grouped by species. Additionally, the use of SIMS to detect microbes on mineral surfaces is demonstrated by an analysis of Shewanella oneidensis on crushed hematite. The results of this study provide evidence for the potential of static SIMS to rapidly detect bacterial species based on ion fragments originating from cell membrane lipids directly from sample surfaces.