Sexual selection plays an important role in the evolution of animals. Today we already know that it takes place not only before copulation (precopulatory sexual selection), but also after copulation. This type of sexual selection is called postcopulatory sexual selection, and occurs mainly in promiscuous species, where females mate with multiple males. In this case, sperm competition occurs in the female reproductive tract. To increase the likelihood of their reproductive success, males began to develop surprisingly diverse sperm adaptations at the morphological, physiological, or behavioural levels. These adaptations often affect sperm velocity (motility), which is a key factor for successful egg fertilization. However, the result of reproductive success can also be influenced by females, who may prefer sperm with a certain phenotype in the process of cryptic female choice, and thus, for example, obtain better genes for offspring. In some species, females even can have the ability to sort and store sperm in specialized organs in which the sperms are nourished for some time, and then used to fertilize the egg. Even in this case, the storage of sperm is often affected by sperm morphology. Due to these mechanisms of postcopulatory sexual selection, sperm are under strong selection pressure, which can...

Emplectonema gracile (Johnston 1837) is a hoplonemertean of marine intertidal hard-bottom communities and is distributed throughout the Northern Hemisphere. Although possessing a planktonic larval stage in its life history, the range of such cosmopolitan marine invertebrate species is often explained by cryptic speciation and anthropogenic transport. The purpose of this study is to test for possible cryptic species using mtDNA markers (COI and 16S rDNA) and to investigate population structure in E. gracile over a portion of its geographic range using mtDNA markers and ddRADseq nuclear SNP data. The results of both phylogenetic- and tree-based species delimitation revealed that E. gracileis a morphotype containing cryptic species. Three North Atlantic and one Pacific coast population are inferred as one species (E. gracile sensu stricto) and two Pacific coast populations (Akkeshi, Japan and Charleston, Oregon) are inferred as another species (Emplectonemasp 1), strongly confirming an earlier study and extending the range of the latter species to the Pacific coast of Japan. Anthropogenic transport is suggested as the likely mode of transport for E. gracile.Both Fst, PCA and haplotype network analyses suggest a lack of differentiation between E. gracile populations separated by large geographic distances.In contrast corresponding analyses forEmplectonemasp. 1 indicate differentiation between the two populations sampled. Further research will be necessary to reveal if rare anthropogenic transport or natural dispersal (larval transport, rafting) between geographically adjacent yet to be delimitedE. gracile morphotype populations is responsible for its seemingly disjunct distribution.

Ranunculus trichophyllus agg. (thread-leaved water crowfoot) represents a taxonomically challenging group of aquatic plants in which the presence of several significantly different genotypes and the genome size variation have been recently revealed. The results of previous studies suggest that cryptic taxa occur in this group, being so far overlooked due to considerable morphological reduction and extensivephenotypic plasticity. In this thesis, the variation and genetic relationships of four morphologically similar homophyllous water-crowfoot species was critically assessed in the area of Central Europe, using a combination of modern biosystematic methods (flow cytometry, direct DNA sequencing, morphometric analyses), specially focusing on the complex of R. trichophyllus.. The genome size analysis via flow cytometry was confirmed as a suitable method for determining the studied species; further, several hybrid combinations were revealed using this approach. However, recent interspecific hybridization is rather infrequent in the interest group. The results of DNA analyses indicate an importance of hybridization events in the evolution of sect. Batrachium: all the polyploid taxa studied are probably of allopolyploid origin. Two cryptic taxa within the traditionally recognized species R. trichophyllus have...

The thesis deals with phylogeny, taxonomy and nomenclature of selected groups of the lichen genus Caloplaca. Particularly, the C. cerina group was closely investigated using molecular methods (ITS sequences), morphology and chemistry, based on material from Europe, and to some extent also from North America and western Asia. This approach resulted in the description of three new species (C. sterilis, C. subalpina, C. thracopontica), and detected an unexpected richness of lineages. Nomenclature, taxonomy, morphology and ecology of C. aurantia and C. flavescens from the C. aurantia group were studied in detail, including selection of the neotype of the former species. Their distribution was reviewed for the territory of the Czech Republic. Poorly known taxon C. aurantiomurorum from Algeria was lectotypified and synonymized with C. aurantia. Apart from the two groups, C. phlogina and C. scythica, differing partly in thallus colour and distinctly in distribution, were examined using both molecular (ITS sequences) and phenotypic data and found to be conspecific.

Regelmäßige Bonituren haben gezeigt, dass virusverdächtige Symptome an Stieleichen, die zu etwa 90 % als chlorotische Ringflecken auftreten, im nord- und mitteldeutschen Raum weit verbreitet sind. In der vorliegenden Arbeit sollte der Erreger dieser Symptome isoliert und näher charakterisiert werden. Aus zwei Blattproben mit chlorotischen Ringflecken konnten stäbchenförmige Viruspartikeln mit einer Länge von ca. 450 nm isoliert und auf krautige Indikatoren übertragen werden. In einer RT-PCR mit Hüllprotein bzw. Transportprotein-sequenzspezifischen Primern wurden diese als Tobacco mosaic virus (TMV)- bzw. Tomato mosaic virus (ToMV)- Isolate identifiziert. Eine Infektion der Stieleichen mit weiteren bekannten Viren von Gehölzen, wie dem Cherry leaf roll virus (CLRV) oder dem Erreger der Ebereschenringfleckigkeit konnte mittels ELISA und RT-PCR ausgeschlossen werden. DsRNAs der Größen 1.5 und 1.6 kb sowie 1.8 und 2.0 kb konnten symptomunabhängig aus Rindengewebe, Knospen und Blättern von Stieleichen isoliert werden. Mit Hilfe der RT-DOP-PCR und der cDNA-Klonierung gelang es, Teile des 1.5/1.6 kb dsRNA-Moleküls zu charakterisieren. Die Sequenz von 479 Aminosäuren (1437 Nukleotiden) wies eine Identität von 56 % zur RNA-abhängigen RNA-Polymerase (RdRp) des Beet cryptic virus 3 (BCV 3) auf. Der spezifische Nachweis dieser Sequenz gelang mittels RT-PCR sowohl in dsRNA-Proben, als auch in angereicherten Nukleokapsiden symptomloser und symptomatischer Stieleichen. In Nested-PCR-Analysen konnte das Fragment jedoch nicht nur in Gesamt-RNA von Stieleichen, sondern auch in Gesamt-RNA und DNA verschiedenster gesunder Pflanzen amplifiziert werden. Phylogenetische Vergleiche mit ausgewählten RdRps viralen und pflanzlichen Ursprungs zeigten die engste Verwandtschaft der Stieleichen-dsRNA-Sequenz zu den Partitiviren, zu denen sich neben BCV 3 auch die endogene dsRNA aus Pyrus und aus Chloroplasten von Bryopsis gruppiert. Diese Erkenntnisse lassen in der charakteristischen Doppelbande von 1.5/1.6 kb das Vorliegen einer endogenen dsRNA vermuten. Hiermit ist in dieser Arbeit das Auftreten verschiedener Viren in Eichen nachgewiesen worden, von denen die meisten höchstwahrscheinlich nicht im direkten ursächlichen Zusammenhang mit der chlorotischen Ringfleckigkeit der Eiche stehen. / Ratings of oak populations revealed that around 90 % of all oak trees affected by viruslike symptoms showed chlorotic ringspots and that these symptoms are widely spread in oaks in north and central Germany. In this study the putative agent of these symptoms should be isolated and specified. Rod-shaped particles with a length of 450 nm were recovered from two different samples of leaves displaying chlorotic ringspots by mechanical inoculation of herbaceous indicator plants. These particles were identified to be Tobacco mosaic virus (TMV)- and Tomato mosaic virus (ToMV)- isolates by RT-PCR analyses of the coat- and movement protein genes. Infections with other well known viruses of forest trees, like Cherry leaf roll virus (CLRV) and the agent causing ringspots in European mountain ash, were excluded by ELISA and RT-PCR. DsRNA fragments of 1.5 and 1.6 kb as well as 1.8 and 2.0 kb were extracted from leaves, inner bark and bulbs of all symptomatic and asymptomatic samples of common oak. The nucleotide sequence of the 1.5 and 1.6 kb dsRNA fragment was partially characterised by reverse transcription degenerated oligonucleotide primed (DOP)-PCR and cDNA cloning. The obtained nucleotide sequence of 1437 nt encoding a putative protein of 479 amino acids revealed an identity of 56 % with the RNA-dependent RNA polymerase (RdRp) of Beet cryptic virus 3 (BCV 3). PCR amplification of the RdRp coding nucleotide sequence was possible using a number of different dsRNA samples as well as concentrated nucleocapside preparations. The same sequence was also amplified successfully by Nested-PCR not only in total RNA extracted from symptomatic and asymptomatic oak samples but also from total RNA and DNA of diverse plants. Phylogenetic analysis revealed further similarities to RdRp´s of endogenous dsRNA of Pyrus and chloroplasts of Bryopsis, both members of the Partitiviridae as well as BCV 3. These results strongly indicate that the 1.5/1.6 kb dsRNA of oak is endogenous dsRNA. In summary, it has been shown that oaks in Germany are commonly infected by a variety of different viruses most of them possibly unrelated to the wide-spread ringspot symptoms of oaks.

No description available.

Made available in DSpace on 2014-12-17T15:18:10Z (GMT). No. of bitstreams: 1 WashingtonCA.pdf: 849606 bytes, checksum: 5c75635780aa8bf93fa4262b0cf3a552 (MD5) Previous issue date: 2009-02-26 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Cytogenetic studies have been revealing a great diversity not detected, until then, in several families of fishes. Many of these groups, especially those that exhibit great diversity, like Perciformes and Siluriformes, possess species with difficult morphologic characterization, called cryptic species, commonly detected through karyotypic analyses, which reveals outstanding interespecific variations with relationship to the number and its chromosomal structures. Thus, the present work intends to contribute for the cytogenetic knowledge of marine and brackish fish species, because they peculiar life habits and by lack of cytogenetic data of your genetic aspects. Therefore, cytogenetic studies were developed in a species of Apogonidae (Perciformes), two species of sea catfishes of the family Ariidae (Siluriformes) and brackish fish Paurachenipterus galeatus (Siluriformes, Auchenipteridae), through C banding, Ag-NOR, use of base-specific flourochromes (DAPI and CMA3), as well as FISH (Fluorescent in situ hybridization) using ribosomal DNA probes 5S and 18S. The present results contribute to a better understanding of the processes of differentiation patterns and chromosome evolution in these groups. The use of other approaches (the morphology and molecular tools) will allow a larger understanding of the genetic and biological diversity of the Brazilian ichthyofauna. / Estudos citogen?ticos t?m revelado uma grande diversidade at? ent?o n?o detectada em diversas fam?lias de peixes. Muitos destes grupos, sobretudo os que exibem grande diversidade, como Perciformes e Siluriformes, possuem esp?cies de dif?cil caracteriza??o morfol?gica, chamadas de esp?cies cr?pticas, muitas vezes s? detectadas atrav?s de an?lises cariot?picas, as quais revelam varia??es interespec?ficas marcantes quanto ao n?mero e estrutura cromoss?mica. Desta forma, o presente trabalho pretende contribuir para o conhecimento citogen?tico de esp?cies marinhos e estuarinos, que, por n?o serem exploradas comercialmente ou terem h?bitos de vida peculiares s?o pouco estudadas quanto aos seus aspectos gen?ticos. Assim, an?lises cariot?picas foram desenvolvidas em uma esp?cie da fam?lia Apogonidae (Perciformes), em duas esp?cies de bagres marinhos da fam?lia Ariidae (Siluriformes), al?m de uma esp?cie de siluriforme estuarino, Paurachenipterus galeatus (Auchenipteridae) atrav?s de bandamento C, Ag-RONs, colora??o com DAPI e CMA3, bem como pela FISH (Fluorescent in situ hibridization), utilizando sondas ribossomais 5S e 18S. Os resultados aqui apresentados indicam grande diversidade inerente a estes grupos. Outras abordagens (an?lises morfol?gicas e ferramentas moleculares) permitir?o obter maior entendimento acerca da diversidade biol?gica da ictiofauna brasileira

Echinocardium cordatum (Pennant 1777) oursin irrégulier abondant des zones côtières tempérées a longtemps été considéré comme une espèce cosmopolite dont la vaste aire de distribution était la conséquence directe des capacités de dispersion de sa larve planctotrophe. L’étude couplée des caractéristiques génétiques [génomes mitochondrial et nucléaire (introns+microsatellites)], morphologiques (étude basée sur 20 indices morphométriques) et écologiques (distribution géographique à petite ou grande échelle, et cycle de maturation gonadique) a révélé la présence d’un complexe d’espèces jumelles dont la différenciation génétique est accompagnée d’une différenciation morphologique statistique ainsi que de différenciations écologiques plus ou moins fines. Ces espèces occupent des aires de distribution limitées (clade A : Atlantique, clade SP : Pacifique Sud, clade NP : Pacifique Nord, clade B2 : Méditerranée, et clade B1 : Méditerranée et côtes atlantiques de l’Ibérie). D’après la reconstruction de l’histoire évolutive de ce complexe, à partir des données paléontologiques et moléculaires, ces espèces auraient divergé il y a 3 (B1-B2) à 10 (A-reste) millions d’années sous l’effet de perturbations géologiques et paléoclimatiques (fermeture de la Téthys, crise messinienne de salinité et glaciations Plio-Pléistocène). Le polymorphisme morphologique et moléculaire apparaît réduit chez B1 suggérant un effectif efficace historique de cette espèce réduit. L’analyse des flux géniques contemporains révèle que les clades A et B1 échangent toujours des gènes, alors que les clades B1 et B2, ont mis en place un isolement reproducteur efficace empêchant l’hybridation. Par ailleurs, les capacités de dispersion des espèces de ce complexe sont importantes (plus de 3000 km), mais moindres comparées à d’autres espèces du genre, notamment E. mediterraneum, qui bien qu’ayant subi les mêmes évènements géologiques n’a pas formé d’espèce depuis son apparition il y aurait 28 millions d’années. D’un point de vue évolutif, les taxons à forte capacité de dispersion présenteraient des tailles efficaces de populations importantes, ainsi qu’une aire de répartition étendue et peu de différentiation génétique entre localités ; autant de caractéristiques qui devraient ralentir la vitesse de spéciation dans ces taxons. Si cette hypothèse semble se vérifier chez E. mediterraneum, il n’en est pas de même chez E. cordatum qui malgré des effectifs efficaces apparemment importants et une différenciation des populations à l’échelle régionale faible, présente une dynamique se spéciation plus rapide. Il faut envisager que d’autres caractéristiques soient à l’origine de cette différence de dynamique de spéciation, et la comparaison des exigences écologiques des deux taxons ainsi que l’isolement de la molécule responsable de la réaction acrosomique, la bindine, pourraient apporter des éléments de réponse aux nouvelles questions soulevées. / Echinocardium cordatum (Pennant 1777) an abundant irregular sea urchin from the coastal temperate zones has long been considered as a cosmopolitan species which wide distribution area was the direct consequence of its planktotrophic larvae high dispersal abilities. A combined study of the genetic [mitochondrial and nuclear genomes (introns+microsatellites)], morphologic (based on 20 morphometric indices) and ecologic (geographic distribution at fine or large scale, and gonad maturation cycle) characteristics reveals that this taxon is a complex of cryptic species for which genetic differentiations concurred with morphological and ecological ones. The different species each occupy a limited geographic areas (clade A : Atlantic, clade SP : South Pacific, clade NP : North Pacific, clade B2 : Mediterranean sea, et clade B1 : Mediterranean sea and Atlantic coasts of Iberia). According to the complex species evolutionary history reconstruction, based on fossils and molecular data, the different species diverged between 3 (B1-B2) and 10 (A-rest) million years ago, driven by geologic and paleoclimatic perturbations (Tethys closure, messinian salinity crisis, Plio-Pleistocene glaciations). Molecular and morphologic polymorphisms appear reduced in B1, suggesting a reduced historical effective size. The contemporaneous genetic flux analysis reveals that clades A and B1 exchange genes whereas clades B1 and B2 developed an efficient reproductive isolation preventing hybridization. Though dispersal abilities of the complex species are high (more than 3000 km), they appear to be smaller than those of other species of the same genera, particularly E. mediterraneum which undergone the same geological perturbations without splitting into several species since its appearance some 28 million years ago. From an evolutionary point of view, taxa with high dispersal abilities should exhibit important population effective sizes, wide distribution areas and weak genetic differentiation between localities, properties that should slow species formation within these taxa. If this hypothesis seems verified in E. mediterraneum, it is not the case in E. cordatum for which the apparent high effective size and weak regional structure contrast with the fast speciation dynamics. It seems that other characteristics might be responsible for the speciation dynamic differences, and the comparison of the two taxa ecological requirements, as well as the isolation of the gene coding for the protein responsible of the sperm specific attachment, the bindin, should bring elements to answer these questions.

CoxsackievirusB3 (CVB3), a member of the Picornaviridae family is the causative agent of Virus-induced Myocarditis and Dilated Cardiomyopathy. The 5’UTR contains an Internal Ribosome Entry Site or IRES element that recruits ribosomes in a cap-independent manner. The ribosomes are recruited upstream of the AUG triplet at 591 (AUG591), also called as the cryptic AUG, after which they scan downstream for about 150 nucleotide, before initiating at the initiator AUG or AUG741. The 3’UTR of CVB3 is 99 nts long, highly structured RNA containing conserved domains, and is followed by a poly (A) tail of variable lengths. We have investigated possible involvement of host proteins which may interact with CVB3 IRES and influence its activity. We have demonstrated the role of Poly-pyrimidine tract binding protein (PTB) and established PTB as a bona-fide ITAF for CVB3, by characterizing the effect of partial silencing of PTB ex-vivo in HeLa cells. The IRES activity in BSC-1 cells, reported to have very low level of endogenous PTB, is found to be significantly low compared to that in HeLa cells. PTB is observed to interact with both the 5’ and 3’ UTR of CVB3, although with different affinities. Finer mapping of the interaction between PTB and the UTRs showed that the protein interacts with multiple regions of both UTRs. We have also shown the cis-acting effect of the CVB3-3’UTR on IRES mediated translation. The PTB contact points on the 3’UTRwas found to map to conserved regions, the deletion of which abrogates the 3’UTR mediated enhancement of the IRES activity. The possible role played by PTB in enhancing IRES activity by CVB3 3’UTR suggests that PTB protein might help in circularization of the CVB3 RNA by bridging the ends necessary for efficient translation of the viral RNA. In the second part, we have investigated possible role of some of the cis-acting element present in the CVB3 5’UTR RNA particularly the cryptic AUG. We have shown that mutation in cryptic AUG reduces the efficiency of translation mediated by the CVB3 IRES. Mutation in cryptic AUG moiety also reduces the interaction of mutant RNA with La protein. We have demonstrated that binding of 48S ribosomal complex with mutant IRES RNA was weaker compared to wt IRES RNA. We have investigated the possible alteration in secondary structure in the mutant RNA by chemical and enzymatic modification, which suggests that there is marginal alteration in the local structure due to mutation. It appears that integrity of cryptic AUG is important for efficient translation initiation by the CVB3 IRES. Results suggest that cryptic AUG plays a significant role in mediating internal initiation of translation of CVB3 RNA by mediating precise La binding and correct positioning of the 48S ribosomal complex. Finally, we have investigated the importance of a conserved hexa-nucleotide stretch in the apical loop within stem loop C (SLC, nt104-180), upstream of the ribosome landing site, on CVB3 IRES function. It has been already shown from our laboratory that the deletion at this apical loop resulted in significant decrease in IRES activity. This deletion mutant was shown to alter the secondary structure of the CVB3 5’UTR RNA. Here we have investigated the effect of point mutation in the apical loop SLC/c on CVB3 IRES activity by generating substitution mutation in the apical loop SLC/c in order to avoid possible alteration in secondary structure. Both the deletion or substitution mutation at this apical loop resulted in significant decrease in IRES activity. Both the mutant IRES RNAs (deletion and substitution mutant) failed to interact with certain trans-acting factors. Furthermore, expression of CVB3 2A protease significantly enhanced IRES activity of the wild type, but the effect was not so pronounced on the mutant IRESs. It is possible that the mutant RNAs were unable to interact with some trans-acting factors critical for enhanced IRES function. We have short-listed three proteins of approximate molecular mass of 56, 64 and 90 kDa, which showed reduced binding with mutant IRESs. By using RNA affinity column with biotinylated UTP labeled RNA we have purified couple of proteins and identified p64 as Cyto Keratin 1 protein by performing in-gel trypsin digestion followed by MALDI analysis. Overall, the results characterize the CVB3 IRES structurally and functionally, which could be useful in targeting critical RNA-protein interactions to develop candidate antiviral agent against Coxsackievirus infection.

The genetic systems involved in the utilisation of aromatic β-glucosides in E. coli consist of the bgl, asc, and chb operons and the locus bglA encoding phospho-β-glucosidase A. The bgl and asc operons are known as cryptic or silent systems since their expression is not sufficient for utilisation of these sugars in wild type strains of E. coli. Their transcriptional activation by different classes of mutations confers a Bgl+ phenotype to the mutant. The maintenance of cryptic genes without accumulating deleterious mutation in spite of being silent is an evolutionary puzzle. Several observations have suggested the possibility that these genes may be expressed under specific physiological conditions conferring a fitness advantage to the organism. The main aim of this study was to investigate the possible role of aromatic β-glucoside catabolic systems of E. coli in combating nutrient stress and microaerobic growth conditions. The results presented in Chapter 2 address the evolution of aromatic β-glucoside catabolic systems when exposed to a novel β-glucoside as the sole substrate. The results indicate that the bgl opeon, the primary system involved in the utilisation of the aromatic β-glucosides arbutin and salicin, is also involved in esculin utilisation. In the absence of bglB encoding the enzyme phospho-β-glucosidase B, activation of the silent asc operon enables esculin utilisation. The bglA gene encoding phospho-β-glucosidase A specific for arbutin, can undergo successive mutations to evolve the ability to hydrolyse esculin and salicin sequentially when bglB and ascB are absent. The Esc+ and Sal+ mutants retain their arbutin+ phenotype, indicating that the mutations enhance the promiscuity of the enzyme. Sequencing data indicate that the first step Esc+ mutant carries a four base insertion within the promoter of the bglA gene that results in enhanced transcription of bglA. RT-PCR studies confirm that both the steady-state levels as well as the half-life of the bglA mRNA are enhanced in the mutant. This is further corroborated by the observation that overexpression of wild type bglA in the parent strain using a multicopy plasmid confers an Esc+ phenotype. The second step Sal+ mutant carries a point mutation within bglA ORF, a thymine to guanine transversion at position 583 (T583G) of the bglA gene, resulting in an amino acid change from cysteine to glycine at position 195 (C195G) of the BglA ORF close to the active site. Presence of a plasmid carrying the T583G mutation, introduced by site-directed mutagenesis, results in a Sal+ phenotype, confirming the role of the transversion in conferring the Sal+ phenotype. Based on docking studies, the positioning of salicin into the substrate binding site of the mutant BglA enzyme is different compared to wild type BglA due to the loss of stearic hindrance for the binding of salicin when C195 is replaced by the smaller amino acid glycine in the mutant protein. These observations indicate that under conditions of nutrient deprivation, exposure to novel substrates can result in the evolution of new metabolic capabilities by the sequential modification of a pre-existing genetic system. In the case of one novel substrate, the mutation results in the overexpression of the hydrolytic enzyme, while in the case of the second substrate, a mutation close to its active site increases its substrate specificity. Results presented in Chapter 3 specifically deal with the involvement of the bgl operon under low levels of oxygen. Earlier observations have shown that there is a 22 fold enhancement in the expression of the bgl operon under anaerobic condition. The present results provide evidence that bgl expression has a physiological role under low levels of oxygen and in addition suggest a possible mechanism for the overexpression of the bgl operon that involves the ArcAB two component system known to mediate regulation under microaerobic and static conditions. Transcription studies using a lacZ reporter fused to the wild type bgl promoter show that there is enhanced transcription from the bgl promoter under microaerobic and static conditions in the presence of arcA encoding the response regulator compared to that in its absence. The positive effect of arcA on the expression of the bgl operon is dispensable in the absence of H-NS since presence or absence of arcA does not change the expression of the bgl operon in an hns-null background, implying that the involvement of ArcA is via antagonizing H-NS. Competition experiments indicate that there is growth advantage associated with the activated allele of the bgl operon under low levels of oxygen since Bgl+ strains carrying the activated allele of the bgl operon as well as strains expressing BglG constitutively can out-compete wild-type strains. Presence of the wild type arcA allele results in a strong growth advantage compared to its absence under static conditions but not aerobic condition. The bgl operon seems to be one of the possible downstream targets of ArcA under static condition since absence of the bgl operon results in a modest reduction of the growth advantage (GASP) phenotype conferred by arcA. The up-regulation of the bgl operon is likely to enable the cells to scavenge available nutrients from their niche more efficiently. These experiments also show that the GASP phenotype associated with BglG constitutive strains under static conditions involves downstream genes that are different from oppA known to be one of the downstream targets during aerobic growth. It is possible that under low level of oxygen, the bgl operon is regulating a different set of downstream genes involving a different mechanism. In summary, the results of this investigation show that the aromatic β-glucoside catabolic systems in E. coli play a role in the generation of new metabolic capabilities via mutations in pre-existing genetic systems as well as through changes in gene expression patterns. The mechanisms outlined in this study are likely to be of broader significance applicable to microbial evolution under stress in general.