Competing Lipid-Protein and Protein-Protein Interactions Determine Clustering and Gating Patterns in the Potassium Channel from Streptomyces lividans (KcsA)

There is increasing evidence to support the notion that membrane proteins, instead of being isolated components floating in a fluid lipid environment, can be assembled into supramolecular complexes that take part in a variety of cooperative cellular functions. The interplay between lipid-protein and protein-protein interactions is expected to be a determinant factor in the assembly and dynamics of such membrane complexes. Here we report on a role of anionic phospholipids in determining the extent of clustering of KcsA, a model potassium channel. Assembly/disassembly of channel clusters occurs, at least partly, as a consequence of competing lipid-protein and protein-protein interactions at nonannular lipid binding sites on the channel surface and brings about profound changes in the gating properties of the channel. Our results suggest that these latter effects of anionic lipids are mediated via the Trp⁶⁷–Glu⁷¹–Asp⁸⁰ inactivation triad within the channel structure and its bearing on the selectivity filter.     

Can Triticum urartu (Poaceae) be identified by pollen analysis? Implications for detecting the ancestor of the extinct two‐grained einkorn‐like wheat

The domestication of the one‐grained einkorn (Triticum monococcum) in the Near East is relatively well known. However, an independent two‐grained einkorn‐like domestication has been archaeobotanically detected and scarce information is available. Triticum urartu, a wild wheat, was not fully described until the 1970s because the phenology does not allow it to be distinguished easily from wild einkorn (Triticum boeoticum subsp. thaoudar), although a genetic separation exists. Both species are mostly two grained and could potentially be the relatives of the extinct two‐grained form. Pollen grains of several genetically well‐identified wheat species, including T. urartu and T. boeoticum subsp. thaoudar, were studied by measuring the grain diameter and examining the exine sculpturing with phase‐contrast microscopy and scanning electron microscopy to gain an insight into differences enabling taxonomic identification. This work showed that, although T. urartu pollen is smaller on average, grain diameter is not sufficient because of the size overlap between the species, but T. urartu presents a different exine sculpturing (scabrate) from other Triticum spp. (aerolate). This outcome is useful for taxonomists and archaeobotanists. First, it will allow a simple re‐classification of herbarium materials. Second, further research could establish whether T. urartu was cultivated. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 278–289.     

Optimization of fibrolytic enzyme production by Aspergillus japonicus C03 with potential application in ruminant feed and their effects on tropical forages hydrolysis

Fibrolytic enzyme production by Aspergillus japonicus C03 was optimized in a medium containing agro-industrial wastes, supplemented with peptone and yeast extract. A 2³ full factorial composite and response surface methodology were used to design the experiments and analysis of results. Tropical forages were hydrolyzed by A. japonicus C03 enzymatic extract in different levels, and they were also tested as enzymatic substrate. Optimal production to xylanase was obtained with soybean bran added to crushed corncob (1:3), 0.01% peptone, and 0.2% yeast extract, initial pH 5.0, at 30 °C under static conditions for 5 days of incubation. Optimal endoglucanase production was obtained with wheat bran added to sugarcane bagasse (3:1), 0.01% peptone, and 0.2% yeast extract, initial pH 4.0, at 30 °C, for 6 days, under static conditions. Addition of nitrogen sources as ammonium salts either inhibited or did not influence xylanase production. This enzymatic extract had a good result on tropical forage hydrolyzes and showed better performance in the Brachiaria genera, due to their low cell wall lignin quantity. These results represent a step forward toward the use of low-cost agricultural residues for the production of valuable enzymes with potential application in animal feed, using fermentation conditions.     

Toward an early marker of metabolic dysfunction: omentin-1 in prepubertal children

Omentin-1 is a recently recognized adipokine primarily originating in visceral adipose tissue. We posited that circulating omentin-1 could be an early marker of metabolic dysfunction. To this end, we examined the associations between circulating omentin-1, body fat (bioelectric impedance), an endocrine-metabolic profile (homeostasis model assessment for insulin resistance (HOMA(IR)), serum lipids, high-molecular-weight (HMW) adiponectin and blood pressure (BP)) and family history of obesity and diabetes in asymptomatic prepubertal children (n = 161; 77 boys and 84 girls; age 7 ± 1 year) with a normal distribution of height and weight. Increased circulating omentin-1 was associated with a poorer metabolic profile, with relatively higher HOMA(IR), fasting triacylglycerol, BP and familial prevalence of diabetes (all P < 0.005 to P < 0.0001), and relatively lower fraction of HMW adiponectin (P < 0.005), whereas no relationship was found with body weight or fat or with family history of obesity. All these associations were independent of age, gender and fat mass. In conclusion, circulating omentin-1 may become a marker of metabolic dysfunction integrating insulin sensitivity, markers of adipose-tissue metabolism and BP as early as in prepubertal childhood.     

Staphylococcal toxic shock syndrome 2000-2006: epidemiology, clinical features, and molecular characteristics

Introduction

Circulating strains of Staphylococcus aureus (SA) have changed in the last 30 years including the emergence of community-associated methicillin-resistant SA (MRSA). A report suggested staphylococcal toxic shock syndrome (TSS) was increasing over 2000–2003. The last population-based assessment of TSS was 1986.

Methods

Population-based active surveillance for TSS meeting the CDC definition using ICD-9 codes was conducted in the Minneapolis-St. Paul area (population 2,642,056) from 2000–2006. Medical records of potential cases were reviewed for case criteria, antimicrobial susceptibility, risk factors, and outcome. Superantigen PCR testing and PFGE were performed on available isolates from probable and confirmed cases.

Results

Of 7,491 hospitalizations that received one of the ICD-9 study codes, 61 TSS cases (33 menstrual, 28 non-menstrual) were identified. The average annual incidence per 100,000 of all, menstrual, and non-menstrual TSS was 0.52 (95% CI, 0.32–0.77), 0.69 (0.39–1.16), and 0.32 (0.12–0.67), respectively. Women 13–24 years had the highest incidence at 1.41 (0.63–2.61). No increase in incidence was observed from 2000–2006. MRSA was isolated in 1 menstrual and 3 non-menstrual cases (7% of TSS cases); 1 isolate was USA400. The superantigen gene tst-1 was identified in 20 (80%) of isolates and was more common in menstrual compared to non-menstrual isolates (89% vs. 50%, p = 0.07). Superantigen genes sea, seb and sec were found more frequently among non-menstrual compared to menstrual isolates [100% vs 25% (p = 0.4), 60% vs 0% (p<0.01), and 25% vs 13% (p = 0.5), respectively].

Discussion

TSS incidence remained stable across our surveillance period of 2000–2006 and compared to past population-based estimates in the 1980s. MRSA accounted for a small percentage of TSS cases. tst-1 continues to be the superantigen associated with the majority of menstrual cases. The CDC case definition identifies the most severe cases and has been consistently used but likely results in a substantial underestimation of the total TSS disease burden.     

Absent or delayed adrenarche in Pit-1/POU1F1 deficiency

Mutations of the PIT1/POU1F1 gene are responsible for a rare variant of anterior hypopituitarism, including deficiency of growth hormone, prolactin and thyrotropin. In 8 ethnically diverse POU1F1-deficient patients (4 different mutations) with normal circulating levels of cortisol and adrenocorticotropic hormone, and with spontaneous onset and progression of puberty, we observed an absence or delay of adrenarche (median circulating dehydroepiandrosterone-sulfate -6.2 SD); in each of the 4 postmenarcheal females, pubarche (i.e. appearance of pubic hair) was also absent or delayed. The absence/delay of adrenarche in POU1F1-deficient patients and the absence/delay of pubarche in POU1F1-deficient females suggest that a POU1F1-dependent factor contributes to the normal development of adrenarche and female pubarche.     

Role of endothelin in mediating postmenopausal hypertension in a rat model

Cardiovascular disease is the leading cause of death in women after menopause. Hypertension, a major cardiovascular risk factor, becomes more prevalent after menopause. The mechanisms responsible for the increase in blood pressure (BP) in postmenopausal women are unknown. We have recently characterized the aged, postestrous-cycling (PMR) spontaneously hypertensive rats (SHR) as a model of postmenopausal hypertension. The purpose of the present study was to determine whether endothelin plays a role in the increased BP in PMR. Premenopausal female SHR, aged 4-5 mo (YF), and PMR, aged 16 mo, were studied. Expression of preproendothelin-1 mRNA was not different in either renal cortex or medulla between PMR and YF (n = 7-8/group). In contrast, ET-1 peptide expression was significantly higher in renal cortex of PMR than in renal cortex of YF, but there was no difference in medullary ET-1. Expression of endothelin ET(A) receptor (ET(A)R) mRNA was lower in renal cortex and medulla of PMR than of YF. Additional groups of rats (n = 6-7/group) were treated for 3 wk with the ET(A)R antagonist ABT-627 (5 mg.kg(-1).day(-1)). BP was significantly higher in PMR than in YF. ET(A)R antagonist reduced BP in PMR by 20% to the level found in control YF. ET(A)R antagonist had no effect on BP in YF. These data support the hypothesis that the increase in BP in PMR is mediated in part by endothelin and the ET(A)R.