Several strains that grow on medium-chain-length alkanes and catalyze interesting hydroxylation and epoxidation reactions do not possess integral membrane nonheme iron alkane hydroxylases. Using PCR, we show that most of these strains possess enzymes related to CYP153A1 and CYP153A6, cytochrome P450 enzymes that were characterized as alkane hydroxylases. A vector for the polycistronic coexpression of individual CYP153 genes with a ferredoxin gene and a ferredoxin reductase gene was constructed. Seven of the 11 CYP153 genes tested allowed Pseudomonas putida GPo12 recombinants to grow well on alkanes, providing evidence that the newly cloned P450s are indeed alkane hydroxylases.Many eubacteria are able to grow on linear alkanes by virtue of alkane hydroxylases (AHs) that activate alkanes to 1-alkanols. These are then further metabolized by alcohol and aldehyde dehydrogenases to fatty acids, which enter the central metabolism (34). AHs belong to several different oxygenase classes. Shortchain-length (C 2 to C 4 )-alkane degraders possess enzymes related to the soluble and particulate methane monooxygenases (34), while integral membrane nonheme iron AHs related to AlkB of Pseudomonas putida GPo1 were found in medium-chain-length (MCL) (C 5 to C 11 )-and especially in long-chain-length (LCL) (ՆC 12 )-alkane-degrading Alpha-, Beta-, and Gammaproteobacteria and high-GϩC gram-positive bacteria (34, 37).Several strains in our collection of alkane degraders grow well on MCL alkanes but could not be shown to contain AlkB homologs that act on MCL alkanes (some of these strains do contain AlkB homologs that hydroxylate LCL alkanes); these strains include the following. (i) Gordonia sp. strain 7E1C (Rhodococcus rhodochrous NCIMB 12566) is of interest because it is able to oxidize substituted phenoxy propane to phenoxy propanoic acids when pregrown on n-alkanes (17). It is known to contain an alkane-inducible cytochrome P450 (2).(ii) For Rhodococcus erythropolis NRRL B-16531 and Q15, none of the integral membrane AHs cloned from these isolates could be shown to act on MCL alkanes (39), even though these and other R. erythropolis isolates grow well on such alkanes (38). (iii) Of several hexane-degrading strains isolated from a trickling-bed bioreactor (32, 39), only 2 of 15 strains tested contained AlkB homologs that oxidize MCL alkanes (J. B. van Beilen et al., unpublished data). This left 13 strains for which growth on hexane initially could not be attributed to known enzyme systems. One of these strains, Sphingomonas sp. strain HXN-200, contains a soluble alkane hydroxylase, which is proposed to be responsible for a range of useful hydroxylation and epoxidation reactions of cyclic compounds such as pyrrolidines, pyrrolidinones, azetidines, azetidinones, piperidines, and piperidinones (4-6, 24, 25). Mycobacterium sp. strain HXN-1500, a strain able to convert limonene to perillyl alcohol (35), was found to contain a soluble alkane hydroxylase that is closely related to the Acinetobacter sp. strain EB104 hexane hydroxylase (CYP...

Pseudomonas sp. VLB120 uses styrene as a sole source of carbon and energy. The first step in this metabolic pathway is catalyzed by an oxygenase (StyA) and a NADH-flavin oxidoreductase (StyB). Both components have been isolated from wild-type Pseudomonas strain VLB120 as well as from recombinant Escherichia coli. StyA from both sources is a dimer, with a subunit size of 47 kDa, and catalyzes the enantioselective epoxidation of CAC double bonds. Styrene is exclusively converted to S-styrene oxide with a specific activity of 2.1 U mg

We have developed highly degenerate oligonucleotides for polymerase chain reaction (PCR) amplification of genes related to the Pseudomonas oleovorans GPo1 and Acinetobacter sp. ADP1 alkane hydroxylases, based on a number of highly conserved sequence motifs. In all Gram-negative and in two out of three Gram-positive strains able to grow on medium- (C6-C11) or long-chain n-alkanes (C12-C16), PCR products of the expected size were obtained. The PCR fragments were cloned and sequenced and found to encode peptides with 43.2-93.8% sequence identity to the corresponding fragment of the P. oleovorans GPo1 alkane hydroxylase. Strains that were unable to grow on n-alkanes did not yield PCR products with homology to alkane hydroxylase genes. The alkane hydroxylase genes of Acinetobacter calcoaceticus EB104 and Pseudomonas putida P1 were cloned using the PCR products as probes. The two genes allow an alkane hydroxylase-negative mutant of Acinetobacter sp. ADP1 and an Escherichia coli recombinant containing all P. oleovorans alk genes except alkB, respectively, to grow on n-alkanes, showing that the cloned genes do indeed encode alkane hydroxylases.

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The Pseudomonas putida GPo1 (commonly known as Pseudomonas oleovorans GPo1) alkBFGHJKL and alkST gene clusters, which encode proteins involved in the conversion of n-alkanes to fatty acids, are located end to end on the OCT plasmid, separated by 97 kb of DNA. This DNA segment encodes, amongst others, a methyl-accepting transducer protein (AlkN) that may be involved in chemotaxis to alkanes. In P. putida P1, the alkBFGHJKL and alkST gene clusters are flanked by almost identical copies of the insertion sequence ISPpu4, constituting a class 1 transposon. Other insertion sequences flank and interrupt the alk genes in both strains. Apart from the coding regions of the GPo1 and P1 alk genes (80-92 % sequence identity), only the alkB and alkS promoter regions are conserved. Competition experiments suggest that highly conserved inverted repeats in the alkB and alkS promoter regions bind AlkS.

In the present study, associations between executive functioning, metacognition, and self-perceived competence in the context of early academic outcomes were examined. A total of 209 children attending first grade were initially assessed in terms of their executive functioning and academic self-concept. One year later, children's executive functioning, academic self-concept, metacognitive monitoring and control, as well as their achievement in mathematics and literacy were evaluated. Structural equation modeling revealed that executive functioning was significantly related to metacognitive control, both crosssectionally and longitudinally, and that self-concept was substantially associated with metacognitive monitoring, both cross-sectionally and longitudinally. Individual differences in executive functioning and metacognitive control were significantly related to academic outcomes, with metacognitive control appearing to yield a more circumscribed influence on academic outcomes (only literacy) compared to executive functioning (literacy and mathematics).

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Research suggests a central role of executive functions for children's cognitive and social development during preschool years, especially in promoting school readiness. Interventions aiming to improve executive functions are therefore being called for. The present study examined the effect of a small group intervention implemented in kindergarten settings focusing on basic components of executive functions, i.e., working memory, interference control and cognitive flexibility. A total of 135 children enrolled in Swiss prekindergarten (5‐year‐olds) and kindergarten (6‐year‐olds) were involved. Results revealed that the small group intervention promoted gains in all three included components of executive functions: prekindergarten children substantially improved their working memory and cognitive flexibility processes, whereas significant training effects were found for the kindergarten children in interference control. Implications of these findings for early intervention programs and for tailoring preschool curricula are discussed, particularly with respect to children's school readiness. Copyright © 2011 John Wiley & Sons, Ltd.