Microclimate and Plant Growth at Isachsen and Mould Bay

In discussing the botany of the northwestern Queen Elizabeth Islands I noted that the available climatic data did not suggest a significant difference between the summer climate of Isachsen and of Mould Bay; yet Mould Bay harbours plant species that are absent from Isachsen, and specimens from there are less depauperate than those from Isachsen. It seemed probable that Mould Bay, which is better protected from winds off the Arctic Ocean, might have less of the very low stratus that often covers Isachsen and which must pass less sunlight than do sheets of high stratus and altostratus. The available data on cloud cover, which do not include cloud height and which are inevitably somewhat subjective, indicated no marked difference between the stations, and sunshine records were lacking for both. With three years' bright sunshine data now available for Isachsen and Mould Bay, I have extracted the summer figures from the Monthly Record of Meteorological Observations in Canada. The growth period at Isachsen extends from mid June to early August, and July is clearly the critical month. The Isachsen total for August 1969 is missing, but for the other 8 months Isachsen exceeded Mould Bay only once. The Mould Bay excess for July was 25 per cent or more in each year. Although soil surface and screen temperatures differ little at Isachsen on heavily overcast days, thermograph records kept by D. St-Onge showed: that on predominantly sunny days the soil surface maxima exceeded the screen maxima by 20-30°F (11-17°C). Thus modest differences in total bright sunshine can be very important to plant growth in this region where almost all activity is confined to the lowest 10 cm of air and much of it to the lowest 3 cm. A longer record is needed before we can fully accept a higher July sunshine figure for Mould Bay; but if the three years of record are nearly representative they must go far in explaining the better growth at this station. However, there is a distinct possibility that diffuse sunlight through thin cloud, not registered by the Campbell-Stokes recorder, adds to Mould Bay's advantage

General Ecology and Vascular Plants of the Hazen Camp Area

Lists 107 vascular plants with brief notes on characteristic habitats. The principal habitiats in a 25 sq mi area are described (map) and the ecological factors analyzed, with June-Aug temperature graph. The general aridity of the area is emphasized, the relative biotic richness being due to favorable summer temperatures, low wind velocity and absence of stratus cloud. Flowering dates for 14 species are tabulated

Mycology in the Canadian Arctic

Reviews studies of fungi north of the limit of spruce, and discusses arctic fungi characteristics and potential scientific significance. Environmental adaptations in reproduction, life cycle, dispersal, host plants, and morphology are described. Extensions in the known ranges of four species are noted

Increase of enzyme activity through specific covalent modification with fragments

Modulation of enzyme activity is a powerful means of probing cellular function and can be exploited for diverse applications. Here, we explore a method of enzyme activation where covalent tethering of a small molecule to an enzyme can increase catalytic activity (k cat/K M) up to 35-fold. Using a bacterial glycoside hydrolase, BtGH84, we demonstrate how small molecule "fragments", identified as activators in free solution, can be covalently tethered to the protein using Michael-addition chemistry. We show how tethering generates a constitutively-activated enzyme-fragment conjugate, which displays both improved catalytic efficiency and increased susceptibility to certain inhibitor classes. Structure guided modifications of the tethered fragment demonstrate how specific interactions between the fragment and the enzyme influence the extent of activation. This work suggests that a similar approach may be used to modulate the activity of enzymes such as to improve catalytic efficiency or increase inhibitor susceptibility

Stereoelectronic effects in the reaction of aromatic substrates catalysed by Halomonas elongata transaminase and its mutants

A transaminase from Halomonas elongata and four mutants generated by an in silico-based design, were recombinantly produced in E. coli, purified and applied to the amination of mono-substituted aromatic carbonyl-derivatives. While benzaldehyde derivatives resulted excellent substrates, only NO2-acetophenones were transformed into the (S)-amine with high enantioselectivity. The different behaviour of wild-type and mutated transaminases was assessed by in silico substrate binding mode studies

Nuclear Structure And Behavior In Species Of The Uredinales

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141150/1/ajb209322.pd

Catalytic Promiscuity of Transaminases : Preparation of Enantioenriched β-Fluoroamines by Formal Tandem Hydrodefluorination/Deamination

Transaminases are valuable enzymes for industrial biocatalysis and enable the preparation of optically pure amines. For these transformations they require either an amine donor (amination of ketones) or an amine acceptor (deamination of racemic amines). Herein transaminases are shown to react with aromatic β-fluoroamines, thus leading to simultaneous enantioselective dehalogenation and deamination to form the corresponding acetophenone derivatives in the absence of an amine acceptor. A series of racemic β-fluoroamines was resolved in a kinetic resolution by tandem hydrodefluorination/deamination, thus giving the corresponding amines with up to greater than 99 % ee. This protocol is the first example of exploiting the catalytic promiscuity of transaminases as a tool for novel transformations