The evolution of carotenoid coloration in estrildid finches: a biochemical analysis

The estrildid finches (Aves: Passeriformes: Estrildidae) of Africa, Asia, and Australia have been the focus of several recent tests of sexual selection theory. Many estrildids display bright red, orange, or yellow colors in the beak or plumage, which typically are generated by the presence of carotenoid pigments. In this study, we used high-performance liquid chromatography to investigate the carotenoid content of feathers and other colorful tissues in seven species of estrildids. Star finches (Neochmia ruficauda) and diamond firetails (Stagonopleura guttata) circulated two main dietary carotenoids (lutein and zeaxanthin) through the blood and liver and used both to acquire a yellow plumage color. However, five other estrildids (common waxbill, Estrilda astrild; black-rumped waxbill, Estrilda troglodytes; zebra waxbill, Amandava subflava; red avadavat, Amandava amandava; and zebra finch, Taeniopygia guttata) circulated these same dietary carotenoids along with two metabolites (dehydrolutein and anhydrolutein) through the blood and/or liver and used all four as yellow plumage colorants. We subsequently tracked the distribution of these pigments using a published phylogeny of estrildid finches to determine the evolutionary pattern of carotenoid metabolism in these birds. We found that finches from the most ancient tribe of estrildids (Estrildini) possessed the ability to metabolize dietary carotenoids. Although carotenoids from the most ancestral extant estrildid species have yet to be analyzed, we hypothesize (based on their relationships with other songbirds known to have such metabolic capabilities) that these finches inherited from their ancestors the capability to metabolize carotenoids. Interestingly, later in estrildid evolution, certain taxa lost the ability to metabolize dietary carotenoids (e.g., in the Poephilini), suggesting that the occurrence of carotenoid metabolism can be labile and is likely shaped by the relative costs and benefits of color signaling across different species.     

Characterization of a cDNA encoding a new member of the glucocorticoid-responsive cytochromes P450 in human liver

Adult human liver contains a form of cytochrome P450, termed HLp, that resembles the glucocorticoid-inducible cytochrome P450p in rat liver in its structure, function, and regulation and catalyzes the oxidation of such clinically important substrates as cyclosporin, nifedipine, erythromycin, and midazolam. Recent evidence, however, suggests that HLp may represent two or more closely related forms of cytochromes P450, one of which is termed P450nf. To search for additional members of the Class III human subfamily of HLp related genes, we screened a human liver cDNA library cloned in phage vector lambda gt11 with oligonucleotides and with a cDNA fragment related to HLp. We isolated a full-length cDNA (1709 nucleotides) encoding a new form of human cytochrome P450 termed HLp2. Analysis of HLp2 cDNA predicted a protein of 502 amino acids, weighing 57,294 Da 83% similar to HLp. HLp2 appears to represent a distinct gene as judged by partial sequence analysis of a cloned human gene and by hybridizations of Southern blots, under conditions of varying stringency, with a 3'-portion of HLp cDNA and with an oligonucleotide specific for HLp2. Northern blot analysis revealed that HLp/P450nf was present in all samples of liver mRNA from adult patients not treated with inducers of HLp, whereas HLp2 mRNA was undetectable in more than two-thirds. Human fetal liver RNA contained mRNA species 2.1 and 1.9 kb which hybridized with an HLp2 oligonucleotide. We conclude that HLp2 represents a third member of the Class III glucocorticoid-responsive gene family that is expressed in both fetal and adult human liver and may account for polymorphism in metabolism of clinically important drugs.     

Anhydrous tetranuclear, dinuclear, and dimeric lanthanide complexes bearing tetradentate Schiff bases

This contribution describes the synthesis and complete characterization of dinuclear (Ln₂(SB)₃) and rigorously dimeric ([(SB)Ln(N(TMS)₂)]₂) lanthanide complexes bearing “saturated” tetradentate Schiff bases (SB). The molecular connectivities, nuclearity, and metal ion coordination geometries in these compounds are governed by the interplay of Schiff-base steric requirements, metal ion radius, and reaction conditions (i.e., solvent choice, concentration, and temperature); the impact of these factors will be discussed and emphasized in the context of structural similarities and notable intramolecular interactions within these related compounds. Also presented is a tetranuclear Nd³⁺ complex exhibiting a ladder arrangement of metal ions and μ-oxo bridges; its formation occurs by the destruction of THF at elevated temperatures. All the compounds presented can be reproducibly synthesized in high yields and analytical purity.     

Mannose-binding lectin deficiency is associated with smaller infarction size and favorable outcome in ischemic stroke patients

Background

The Mannose-binding lectin (MBL) pathway of complement plays a pivotal role in the pathogenesis of ischemia/reperfusion (I/R) injury after experimental ischemic stroke. As comparable data in human ischemic stroke are limited, we investigated in more detail the association of MBL deficiency with infarction volume and functional outcome in a large cohort of patients receiving intravenous thrombolysis or conservative treatment.

Methodology/Principal Findings

In a post hoc analysis of a prospective cohort study, admission MBL concentrations were determined in 353 consecutive patients with an acute ischemic stroke of whom 287 and 66 patients received conservative and thrombolytic treatment, respectively. Stroke severity, infarction volume, and functional outcome were studied in relation to MBL concentrations at presentation to the emergency department. MBL levels on admission were not influenced by the time from symptom onset to presentation (p = 0.53). In the conservative treatment group patients with mild strokes at presentation, small infarction volumes or favorable outcomes after three months demonstrated 1.5 to 2.6-fold lower median MBL levels (p = 0.025, p = 0.0027 and p = 0.046, respectively) compared to patients with more severe strokes. Moreover, MBL deficient patients (<100 ng/ml) were subject to a considerably decreased risk of an unfavorable outcome three months after ischemic stroke (adjusted odds ratio 0.38, p<0.05) and showed smaller lesion volumes (mean size 0.6 vs. 18.4 ml, p = 0.0025). In contrast, no association of MBL concentration with infarction volume or functional outcome was found in the thrombolysis group. However, the small sample size limits the significance of this observation.

Conclusions

MBL deficiency is associated with smaller cerebral infarcts and favorable outcome in patients receiving conservative treatment. Our data suggest an important role of the lectin pathway in the pathophysiology of cerebral I/R injury and might pave the way for new therapeutic interventions.     

A Standardized Vascular Disease Health Check in Europe: A Cost-Effectiveness Analysis

Background

No clinical trials have assessed the effects or cost-effectiveness of health check strategies to detect and manage vascular disease. We used a mathematical model to estimate the cost-effectiveness of several health check strategies in six European countries.

Methods

We used country-specific data from Denmark, France, Germany, Italy, Poland, and the United Kingdom to generate simulated populations of individuals aged 40–75 eligible for health checks in those countries (e.g. individuals without a previous diagnosis of diabetes, myocardial infarction, stroke, or serious chronic kidney disease). For each country, we used the Archimedes model to compare seven health check strategies consisting of assessments for diabetes, hypertension, lipids, and smoking. For patients diagnosed with vascular disease, treatment was simulated in a standard manner. We calculated the effects of each strategy on the incidence of type 2 diabetes, major adverse cardiovascular events (MACE), and microvascular complications in addition to quality of life, costs, and cost per quality-adjusted life-year (QALY).

Results

Compared with current care, health checks reduced the incidence of MACE (6–17 events prevented per 1000 people screened) and diabetes related microvasular complications (5–11 events prevented per 1000 people screened), and increased QALYs (31–59 discounted QALYs) over 30 years, in all countries. The cost per QALY of offering a health check to all individuals in the study cohort ranged from €14903 (France) to cost saving (Poland). Pre-screening the population and offering health checks only to higher risk individuals lowered the cost per QALY. Pre-screening on the basis of obesity had a cost per QALY of €10200 (France) or less, and pre-screening with a non-invasive risk score was similar.

Conclusions

A vascular disease health check would likely be cost effective at 30 years in Denmark, France, Germany, Italy, Poland, and the United Kingdom.     

ABC transporters coordinately expressed during lignification of Arabidopsis stems include a set of ABCBs associated with auxin transport

The primary inflorescence stem of Arabidopsis thaliana is rich in lignified cell walls, in both vascular bundles and interfascicular fibres. Previous gene expression studies demonstrated a correlation between expression of phenylpropanoid biosynthetic genes and a subset of genes encoding ATP-binding cassette (ABC) transporters, especially in the ABCB/multi-drug resistance/P-glycoprotein (ABCB/MDR/PGP) and ABCG/pleiotropic drug resistance (ABCG/PDR) subfamilies. The objective of this study was to characterize these ABC transporters in terms of their gene expression and their function in development of lignified cells. Based on in silico analyses, four ABC transporters were selected for detailed investigation: ABCB11/MDR8, ABCB14/MDR12, ABCB15/MDR13, and ABCG33/PDR5. Promoter::glucuronidase reporter assays for each gene indicated that promoters of ABCB11, ABCB14, ABCB15, and ABCG33 transporters are active in the vascular tissues of primary stem, and in some cases in interfascicular tissues as well. Homozygous T-DNA insertion mutant lines showed no apparent irregular xylem phenotype or alterations in interfascicular fibre lignification or morphology in comparison with wild type. However, in abcb14-1 mutants, stem vascular morphology was slightly disorganized, with decreased phloem area in the vascular bundle and decreased xylem vessel lumen diameter. In addition, abcb14-1 mutants showed both decreased polar auxin transport through whole stems and altered auxin distribution in the procambium. It is proposed that both ABCB14 and ABCB15 promote auxin transport since inflorescence stems in both mutants showed a reduction in polar auxin transport, which was not observed for any of the ABCG subfamily mutants tested. In the case of ABCB14, the reduction in auxin transport is correlated with a mild disruption of vascular development in the inflorescence stem.     

CYP3A5 genotype predicts renal CYP3A activity and blood pressure in healthy adults.

A single-nucleotide polymorphism (A6986G) in the cytochrome p-450 3A5 (CYP3A5) gene distinguishes an expressor (*1) and a reduced-expressor (*3) allele and largely predicts CYP3A5 content in liver and intestine. CYP3A5 is the prevailing CYP3A isoform in kidney. We report that, among renal microsomes from 21 organ donors, those from *1/*3 individuals had at least eightfold higher mean kidney microsomal CYP3A5 content and 18-fold higher mean CYP3A catalytic activity than did those from *3/*3 individuals (P = 0.0001 and P = 0.0137, respectively). We also report significant associations between the A6986G polymorphism and systolic blood pressure (P = 0.0007), mean arterial pressure (P = 0.0075), and creatinine clearance (P = 0.0035) among 25 healthy African-American adults. These associations remained significant when sex, age, and body mass index were taken into account. The mean systolic blood pressure of homozygous CYP3A5 expressors (*1/*1) exceeded that of homozygous nonexpressors (*3/*3) by 19.3 mmHg. We speculate whether a high CYP3A5 expressor allele frequency among African-Americans may contribute to a high prevalence of sodium-sensitive hypertension in this population.     

Spatiotemporal coupling of cAMP transporter to CFTR chloride channel function in the gut epithelia

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-regulated chloride channel localized at apical cell membranes and exists in macromolecular complexes with a variety of signaling and transporter molecules. Here, we report that the multidrug resistance protein 4 (MRP4), a cAMP transporter, functionally and physically associates with CFTR. Adenosine-stimulated CFTR-mediated chloride currents are potentiated by MRP4 inhibition, and this potentiation is directly coupled to attenuated cAMP efflux through the apical cAMP transporter. CFTR single-channel recordings and FRET-based intracellular cAMP dynamics suggest that a compartmentalized coupling of cAMP transporter and CFTR occurs via the PDZ scaffolding protein, PDZK1, forming a macromolecular complex at apical surfaces of gut epithelia. Disrupting this complex abrogates the functional coupling of cAMP transporter activity to CFTR function. Mrp4 knockout mice are more prone to CFTR-mediated secretory diarrhea. Our findings have important implications for disorders such as inflammatory bowel disease and secretory diarrhea.     

Effects of lipid environment on the conformational changes of an ABC importer

In order to shuttle substrates across the lipid bilayer, membrane proteins undergo a series of conformation changes that are influenced by protein structure, ligands, and the lipid environment. To test the effect of lipid on conformation change of the ABC transporter MolBC, EPR studies were conducted in lipids and detergents of variable composition. In both a detergent and lipid environment, MolBC underwent the same general conformation changes as detected by site-directed EPR spectroscopy. However, differences in activity and the details of the EPR analysis indicate conformational rigidity that is dependent on the lipid environment. From these observations, we conclude that native-like lipid mixtures provide the transporter with greater activity and conformational flexibility as well as technical advantages such as reconstitution efficiency and protein stability.