Lacticin 481: in vitro reconstitution of lantibiotic synthetase activity     

Xie L  Miller LM  Chatterjee C  Averin O  Kelleher NL  van der Donk WA 《Science (New York, N.Y.)》2004,303(5658):679-681

The lantibiotic lacticin 481 is synthesized on ribosomes as a prepeptide (LctA) and posttranslationally modified to its mature form. These modifications include dehydration of serines and threonines, followed by intramolecular addition of cysteines to the unsaturated amino acids, which generates cyclic thioethers. This process breaks eight chemical bonds and forms six newbonds and is catalyzed by one enzyme, LctM. We have characterized the in vitro activity of LctM, which completely processed a series of LctA mutants, displaying a permissive substrate specificity that holds promise for antibiotic engineering.  相似文献   

Erwinia carotovora subsp.atroseptica infection promotes verticillium wilt development in potato in Israel     

Leah Lahkim Tsror  A. Nachmias  L. Livescu  M. C. M. Perombelon  Z. Barak 《Potato Research》1990,33(1):3-11

Summary The interaction betweenErwinia carotovora subsp.atroseptica (Eca) andVerticillium dahliae and its effect on symptom development in potato cultivars showing different degrees of resistance to them was examined over two seasons in irrigated fields in a hot, dry climate. Four cultivars were used: Cara, highly resistant to blackleg and tolerant to Verticillium wilt; Pentland Crown also resistant to blackleg but susceptible to Verticillium wilt; Désirée, moderately susceptible to blackleg but tolerant to Verticillium wilt; and Maris Bard, susceptible to both diseases. Seed tubers were inoculated with Eca immediately after harvest in Scotland, to simulate natural infection, and then planted in Israel in soil naturally infested byV. dahliae. In Verticillium tolerant cultivars, Eca infection increased the rate of colonization byV. dahliae and significantly enhanced symptom development, as assessed by suppression of plant height and wilt symptoms. This report is a portion of the Ph.D. thesis of the senior author in Ben-Gurion University of the Negev.  相似文献   

Summer drought effects upon soil and litter extracellular phenol oxidase activity and soluble carbon release in an upland Calluna heathland     

Hannah Toberman  Chris D. Evans  Christopher Freeman  Nathalie Fenner  Marie White  Bridget A. Emmett  Rebekka R.E. Artz 《Soil biology & biochemistry》2008,40(6):1519-1532

Extracellular phenol oxidases play an important role in the soil carbon cycle. The effects of a field-scale summer drought manipulation on extracellular litter and soil phenol oxidase activity, soluble phenolic compounds and dissolved organic carbon concentrations were examined for an upland Calluna heathland on a peaty podsol in North Wales. Litter and organic soil phenol oxidase activity was found to be positively correlated with moisture content. Thus in shallow organic soils, which are sensitive to drying during periods of low rainfall, drought may inhibit soil phenol oxidase activity as a result of water limitations. The release of soluble phenolic compounds and DOC from the droughted plots was found to be lowered during the drought period and elevated outside of the drought period. It is hypothesized that these changes may be a result of the reduced ability of extracellular phenol oxidases to process recalcitrant polyphenolic material under drought conditions. A drying incubation carried out with litter and soil cores from the same site suggests that extracellular phenol oxidase activity displays an optimal moisture level. This reconciled the observed water limitation of phenol oxidase activity at the heathland experimental site with previously observed stimulation of phenol oxidase activity by water table drawdown in deeper peats.  相似文献   

Supporting the Research Practices of Agricultural Scientists at Oregon State University     

Hannah Gascho Rempel  M. Brooke Robertshaw 《Journal Of Agricultural & Food Information》2017,18(3-4):276-292

ABSTRACT

As part of a cross-institutional collaboration organized by Ithaka S+R, Oregon State University Libraries faculty interviewed 15 faculty members in the College of Agricultural Sciences about their research, publishing, and information management practices. The work of Agricultural Sciences faculty is uniquely influenced by their regional geography and climate, as well as by their local and disciplinary communities of practice, which includes both growers and scholars. Findings showed that publishing decisions, access to research, barriers to access, and a systems thinking approach were influenced by behaviors and standards established by these various communities. Implications for the libraries' role in discovery, access, and dissemination are considered and discussed.  相似文献   

Effect of auriculopalpebral nerve block on Schirmer tear test I values in normal horses          下载免费PDF全文

Hannah E. Visser  Kathryn A. Diehl  R. David Whitley  Kathern E. Myrna 《Veterinary ophthalmology》2017,20(6):568-570

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Eradication of common mynas Acridotheres tristis from Denis Island,Seychelles          下载免费PDF全文

Chris J Feare  Jildou van der Woude  Phill Greenwell  Hannah A Edwards  Jenni A Taylor  Christine S Larose  Per‐Arne Ahlen  Jack West  Will Chadwick  Smita Pandey  Katherine Raines  Fernando Garcia  Jan Komdeur  Arjan de Groene 《Pest management science》2017,73(2):295-304

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Direct Measurement of CO₂ Retention in Arable Soils with pH Above 6.5 During Barometric Process Separation Incubation     

Hannah CONRADS  Joachim INGWERSEN  JU Xiaotang  Thilo STRECK 《土壤圈》2018,28(5):726-738

The barometric process separation(BaPS)technique is a well-established incubation method to simultaneously measure gross nitrification and respiration rates in soil.Its application,however,is still critical in soils with pH above 6.5.Here,a substantial part of microbial CO_2 production is retained in soil solution(CO_2,aq)due to shifts in the carbonate equilibrium.This may lead to substantial errors in gas balance calculation.Yet,utilization of the BaPS technique is only reliable if the critical term is adequately quantified.We present an easy,inexpensive,and direct method,the sterilization-CO_2-injection(SCI)method,to measure CO_2 retention during soil incubation.Sterilized soil was incubated in the BaPS system,and defined volumes of CO_2 were injected to stepwise increase CO_2partial pressure(p CO_2)inside the chamber and to analyse the physicochemical equilibration process.Five exemplary agricultural soils from Northeast China and Southwest Germany were used for method establishment,presenting pH values between 4.4 and 7.6 and carbonate contents between 0% and 3.9%.We observed that in soils with pH6.5,70%–90% of the injected CO_2 was taken up by the soil until the equilibrium inside the chamber was re-established.As expected,in soils with low pH(6.5),measured CO_2 retention was low.CO_2 retention patterns were sensitive to incubation temperature with tri-fold dissolution capacity at 5~?C compared to 25?C,but insensitive to variations in soil water content.The resulting soil-specific relationship between p CO_2 and CO_2,aq concentration allowed the quantification of CO_2,aq concentration as a function of headspace p CO_2.  相似文献