Characterisation of sucrose lactate and other oligosaccharides found in the cladophorales

Oligosaccharides not previously recorded in the Cladophorales (green algae) have been separated from the 80% ethanolic extract and characterised. 4-O-Lactyl-β- -fructofuranosyl - -glucopyranoside (sucrose lactate) was found only in Cladophora laetevirens and a fresh-water Rhizoclonium species. Panose, maltotriose, maltotetraose, and 6-O- -glucosylmaltotriose appear to be common to all the species examined¹.     

Chemistry of the polysaccharides of the diatom Coscinodiscus nobilis

The extracellular polysaccharide of Coscinodiscus nobilis, a member of the Coscinodiscaceae, contains a highly branched heteropolysaccharide(s) containing fucose, rhamnose, mannose, d-glucose, xylose, d-glucuronic acid, galactose (trace) and half ester sulphate. The positions of linkages between the monosaccharides have been established and evidence for the linkages between d-glucuronic acid and monosaccharides was obtained. The extracellular polysaccharide contained also a chrysolaminaran, but this may have been derived from dead cells. Fucose and mannose occur also in a separate polymer. The diatom contained polysaccharide material consisting of glucose, mannose, fucose and uronic acid residues.     

Indole-3-ethanol Oxidase: Kinetics, Inhibition, and Regulation by Auxins

We report the further characterization of indole-3-ethanol oxidase from cucumber seedlings. The effects of various inhibitors suggest that the enzyme may be a flavoprotein with a metal ion and sulfhydryl groups required for full activity. Indole-3-acetaldehyde, a product of the reaction, inhibits the enzyme. This inhibition is overcome by O₂ but not by indole-3-ethanol, indicating that the kinetic mechanism of the enzyme is a ping-pong Bi-Bi. The enzyme undergoes cooperative interactions with indoleethanol, yielding Hill coefficients as high as 2.96. Gibberellins are without effect on the enzyme, but it is inhibited by several acidic indoles possessing growth-promoting activity and by two synthetic auxins, 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. Increasing concentrations of indoleacetic acid (IAA) brought about a slight reduction in the indoleethanol concentration producing halfmaximal velocity. Increasing levels of indoleethanol decreased the concentration of IAA required for half-maximal inhibition. At low concentrations of indoleethanol, low levels of IAA activated rather than inhibited. The effect of IAA was not overcome at higher levels of indoleethanol. These results may be interpreted as showing that IAA is a noncompetitive inhibitor which binds to that conformation of the enzyme which also binds indoleethanol. The significance of these interactions for the regulation of IAA biosynthesis is discussed.     

NESTMATE RELATEDNESS IN A COMMUNAL BEE,PERDITA TEXANA (HYMENOPTERA: ANDRENIDAE), BASED ON DNA FINGERPRINTING

Perdita texana is a facultatively communal bee species with up to 28 females per nest. We used multilocus DNA fingerprinting to test the hypothesis that nestmates are more closely related to each other than are nonnestmates. The mean band sharing proportion among pairwise nestmate comparisons did not differ significantly from the mean among nonnestmate comparisons [P = 0.787 (df = 484)]. Although mean band sharing proportions did not differ among nestmates and nonnestmates, some nestmates show very high band sharing proportions (in excess of the upper 95% confidence limit for the nonnestmate mean). These individuals almost certainly are related, probably as half-sib sisters, however, they comprise a very small percentage of the nestmate populations. Our results indicate that kin selection is unlikely to play an important role in the evolution and maintenance of communal nesting. Communal societies most likely arise because of the mutualistic benefits of cooperative nesting, including accelerated nest founding and improved nest defense.     

Intertidal habitat loss and wildfowl numbers: applications of a spatial depletion model

1. A spatial depletion model of the responses of grazing wildfowl to the availability of intertidal vegetation at Lindisfarne National Nature reserve, north-east England, was used to investigate the capacity of the site's beds of Zostera and other intertidal vegetation to support brent geese Branta bernicla hrota and wigeon Anas penelope .
2. Recent total winter counts of brent geese and wigeon were both only 40% of the maximum that the food supply at the site could theoretically support. Other factors must have been restricting their numbers. Earlier arrival of brent geese at the site could increase the number of brent goose-days which could be supported, but would have only a slight negative effect on the wigeon-days.
3. The model was used to examine three conservation issues: encroachment of Spartina anglica , sea level rise and loss of food plants from the whole site (which could result from increased autumn storms or plant disease). Loss from the top of the shore through encroachment by Spartina anglica had the greatest effect on the site's capacity to sustain geese and wigeon. Loss from the bottom of the shore, as would occur through sea level rise, had less impact. Increased loss of vegetation over the whole site would have an intermediate effect.
4. This work has important implications for the management of the site. Factors such as hunting, that may be restricting current numbers below those that could be supported by the food supply, require urgent investigation. Model predictions indicate that encroachment of Spartina is likely to depress local populations of brent geese and wigeon under current conditions only if it results in the complete loss of Zostera from the top 500 m of the shore.     

Consultant Input in Acute Medical Admissions and Patient Outcomes in Hospitals in England: A Multivariate Analysis

Recent recommendations for physicians in the UK outline key aspects of care that should improve patient outcomes and experience in acute hospital care. Included in these recommendations are Consultant patterns of work to improve timeliness of clinical review and improve continuity of care. This study used a contemporaneous validated survey compared with clinical outcomes derived from Hospital Episode Statistics, between April 2009 and March 2010 from 91 acute hospital sites in England to evaluate systems of consultant cover for acute medical admissions. Clinical outcomes studied included adjusted case fatality rates (aCFR), including the ratio of weekend to weekday mortality, length of stay and readmission rates. Hospitals that had an admitting Consultant presence within the Acute Medicine Unit (AMU, or equivalent) for a minimum of 4 hours per day (65% of study group) had a lower aCFR compared with hospitals that had Consultant presence for less than 4 hours per day (p<0.01) and also had a lower 28 day re-admission rate (p<0.01). An ‘all inclusive’ pattern of Consultant working, incorporating all the guideline recommendations and which included the minimum Consultant presence of 4 hours per day (29%) was associated with reduced excess weekend mortality (p<0.05). Hospitals with >40 acute medical admissions per day had a lower aCFR compared to hospitals with fewer than 40 admissions per day (p<0.03) and had a lower 7 day re-admission rate (p<0.02). This study is the first large study to explore the potential relationships between systems of providing acute medical care and clinical outcomes. The results show an association between well-designed systems of Consultant working practices, which promote increased patient contact, and improved patient outcomes in the acute hospital setting.     

Increasing cellulose accessibility is more important than removing lignin: A comparison of cellulose solvent‐based lignocellulose fractionation and soaking in aqueous ammonia

While many pretreatments attempt to improve the enzymatic digestibility of biomass by removing lignin, this study shows that improving the surface area accessible to cellulase is a more important factor for achieving a high sugar yield. Here we compared the pretreatment of switchgrass by two methods, cellulose solvent‐ and organic solvent‐based lignocellulose fractionation (COSLIF) and soaking in aqueous ammonia (SAA). Following pretreatment, enzymatic hydrolysis was conducted at two cellulase loadings, 15 filter paper units (FPU)/g glucan and 3 FPU/g glucan, with and without BSA blocking of lignin absorption sites. The hydrolysis results showed that the lignin remaining after SAA had a significant negative effect on cellulase performance, despite the high level of delignification achieved with this pretreatment. No negative effect due to lignin was detected for COSLIF‐treated substrate. SEM micrographs, XRD crystallinity measurements, and cellulose accessibility to cellulase (CAC) determinations confirmed that COSLIF fully disrupted the cell wall structure, resulting in a 16‐fold increase in CAC, while SAA caused a 1.4‐fold CAC increase. A surface plot relating the lignin removal, CAC, and digestibility of numerous samples (both pure cellulosic substrates and lignocellulosic materials pretreated by several methods) was also developed to better understand the relative impacts of delignification and CAC on glucan digestibility. Biotechnol. Bioeng. 2011; 108:22–30. © 2010 Wiley Periodicals, Inc.