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Evidence for the evolution of a single component phenol/cresol hydroxylase from a multicomponent toluene monooxygenase (1997)

Olsen, R H ; Kukor, J J ; Byrne, A M ; [et al.]

Springer

Journal of industrial microbiology and biotechnology 19 (1997), S. 360-368

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ISSN: 1476-5535

Keywords: Keywords: Burkholderia pickettii PKO1; Pseudomonas sp strain JS150; phenol hydroxylase; multicomponent oxygenases; molecular evolution; transcriptional regulation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology

Notes: We have previously reported on the organization of a unique toluene-3-monooxygenase pathway for the degradation of alkyl-substituted petroleum hydrocarbons including characteristics of the second step in the pathway transforming phenols to catechols. In the present work we have focused on the regulation and unusual genetic organization of this metabolic step. In particular, we have sequenced the 3-kb DNA interval between the region encoding the tbuD gene product (phenol/cresol hydroxylase) and part of the toluene-3-monooxygenase operon of strain PKO1. Then, various regions of this DNA were fused to a LacZ expression system to ascertain the location of the tbuD gene promoter and the binding site for its regulator, TbuT. The 5′ end for transcripts for the putative promoter of the tbuD gene was also analyzed using primer extension analysis. Collectively, these results revealed that the promoter was located 2.5-kb upstream of the region encoding the tbuD gene product whose N-terminal region had been previously determined by peptide sequencing. Remarkably, the intervening 2.5-kb region showed sequence identity to results we reported previously for a multi-subunit toluene-2-monooxygenase cloned from a different bacterium, strain JS150, for which phenols are also substrates and effectors. When the DNA sequence for the tbuD gene and its contiguous 2.5-kb upstream region were compared to the entire toluene-2-monooxygenase sequence cloned from strain JS150, a promoter proximal region encoding three reading frames showed 99% identity to subunits for the toluene-2-monooxygenase operon. Within the contiguous tbuD gene region, however, DNA sequence homology was reduced to 64% overall identity and deduced amino acid sequence homology was only 21% similar. Although regions internal to the tbuD gene showed homology to corresponding toluene-2-monooxygenase subunits, domains associated with the putative functions proposed for such subunits were deleted. We believe that these results suggest that through evolution either tbuD was derived from the 2-monooxygenase pathway by deletions and molecular rearrangements, or alternatively the tbuD gene recruited part of the 2-monooxygenase pathway and its regulatory system which is activated by benzene, alkyl-substituted benzenes and phenols.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/sj.jim.2900453

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The digestion of protein and carbohydrate by the stream detritivore, Tipula abdominalis (Diptera, Tipulidae) (1980)

Martin, M. M. ; Martin, J. S. ; Kukor, J. J. ; [et al.]

Springer

Oecologia 46 (1980), S. 360-364

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ISSN: 1432-1939

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The digestive system of larvae of Tipula abdominalis (Diptera, Tipulidae), a stream detritivore, is poorly adapted for the digestion of the major polysaccharides in its diet, but well adapted for the digestion of protein. These crane fly larvae are unable to digest the major cell wall polysaccharides of higher plants, i.e., cellulose, hemicellulose and pectin. The only polysaccharides toward which the midguts of T. abdominalis exhibited any activity were α-amylose and laminarin, indicating that polysaccharide digestion is restricted to α-1,4-and β-1,3-glucans. The most concentrated source of these two classes of carbohydrates in submerged leaf litter would be associated fungal tissue. The midgut of T. abdominalis is strongly alkaline throughout, with a maximum pH near 11.5 in a narrow zone near the midpoint. Proteolytic activity in the midgut is extraordinarily high, and the pH optimum for midgut proteolytic activity is above 11. We conclude that the high alkalinity and high proteolytic activity observed in T. abdominalis larvae are manifestations of a highly efficient protein-digesting system, a system of crucial importance to a nitrogen-limited organism which must derive its nitrogen from a resource in which much of the limited nitrogen present is in a “bound” form in complexes of proteins with lignins and polyphenols.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00346265

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The nutritional ecology of larvae of Alsophila pometaria and Anisota senatoria feeding on early- and late-season oak foliage (1984)

Lawson, D. L. ; Merritt, R. W. ; Martin, M. M. ; [et al.]

Springer

Entomologia experimentalis et applicata 35 (1984), S. 105-114

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ISSN: 1570-7458

Keywords: Alsophila pometaria ; Geometridae ; Anisota senatoria ; Citheroniidae ; Quercus ; nutritional ecology ; herbivory ; nutritional indices ; consumption ; growth ; utilization efficiency ; nitrogen ; water ; tannins ; phenols ; gut pH ; digestive enzymes

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Description / Table of Contents: Résumé Alimentées sur feuillage jeune de chêne, les chenilles d'Alsophila pometaria avaient un taux relatif de croissance (RGR) et un taux relatif d'accumulation d'azote (RNAR) plus élevés que les chenilles d'Anisota senatoria alimentées sur feuillage mûr de chêne. Bien que le jeune feuillage soit plus efficacement digéré par A. pometaria (AD plus élevé), il n'est pas assimilé et utilisé pour la croissance avec de meilleurs rendements (les ECI ne sont pas différents). Ainsi le taux de croissance plus élevé d'A. pometaria est dû entièrement à un taux de consommation plus important (RCR et RNCR). Le feuillage jeune est significativement plus riche en azote et en eau que le feuillage mûr, mais les niveaux de phénol et de tanins sont les mêmes. A pometaria consomme les feuilles de différentes espèces de chênes au même taux, indépendamment de la teneur en azote, tandis que A. senatoria accroît sa consommation en réponse à une diminution de la teneur en azote. Il en résulte que le taux de croissance d'A. pometaria dépend directement de la teneur en azote des feuilles, tandis que celui d'A. senatoria en est indépendant. Les systèmes digestifs des deux insectes sont biochimiquement semblables et sont efficaces pour la digestion des protéines. Les tanins et les phénols n'influent pas sur les indices nutritionnels de ces deux espèces. Nous estimons que le principal intérêt de l'alimentation printanière est la disponibilité en feuillage succulent, riche en azote, et non l'absence de feuilles à haute teneur en tanin. L'alimentation printanière semble correspondre à une strategie alimentaire qui favorise la croissance aux dépens de l'efficacité tandis que l'alimentation en fin d'été est une stratégie qui favorise l'efficacité sur la rapidité.

Notes: Abstract The larvae of Alsophila pometaria (Harr.), feeding on the young foliage of oak, has a higher relative growth rate (RGR) and relative nitrogen accumulation rate (RNAR) than the larvae of Anisota senatoria (J. E. Smith), feeding on the mature foliage of oak. Although the young oak foliage is more efficiently digested by A. pometaria (higher AD's), it is not more efficiently assimilated and used for growth (no difference in ECI's). Thus, the higher growth rate of A. pometaria is due entirely to a higher consumption rate (RCR and RNCR). Young foliage is significantly higher in nitrogen and water than mature foliage, but phenol and tannin levels are comparable in young and old foliage. A. pometaria consumes the foliage of different oak species at the same rate, independent of nitrogen content, while A. senatoria increases its consumption rate in response to decreased nitrogen levels. As a result, the growth rate of A. pometaria is directly related to leaf nitrogen content, while the growth rate of A. senatoria is independent of leaf nitrogen. The two species of insects have digestive systems that are very similar biochemically, and that are well-designed for effective protein digestion. Tannins and phenols do not influence the nutrional indices of either species. We suggest that the major benefit of spring feeding is the availability of succulent, high-nitrogen foliage, and not the avoidance of high-tannin foliage. The spring feeder appears to have a feeding strategy that favors rapid growth at the expense of efficiency, while the late summer feeder has a strategy that favors efficiency over rate.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00217527

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