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  • Chemistry  (85)
  • Cell & Developmental Biology  (29)
  • Corynebacterium glutamicum  (4)
  • Evolution  (4)
  • 1
    Electronic Resource
    Electronic Resource
    General organization of the genes specifically involved in the diaminopimelate-lysine biosynthetic pathway of Corynebacterium glutamicum (1988)
    Springer
    Molecular genetics and genomics 212 (1988), S. 105-111 
    Details
    ISSN: 1617-4623
    Keywords: Corynebacterium glutamicum ; Diaminopimelate-lysine anabolic pathway ; Heterologous complementation ; Homologous expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We utilized diaminopimelate-lysine mutants of Escherichia coli K12 to clone the genes specifically involved in the Corynebacterium glutamicum diaminopimelate-lysine anabolic pathway. From a cosmid genomic bank of C. glutamicum strain AS019, we isolated cosmids pSM71, pSM61 and pSM531, that are respectively able to complement dapA/dapB, dapD, and lysA mutants of E. coli. DNA hybridization analysis indicates that these complementing genes are located on the chromosome of C. glutamicum in at least three separate transcription units. Subcloning of parental cosmids in dapA, dapD, and lysA mutants of E. coli localized these genes, respectively, within 1.4, 3.4, and 1.8 kb fragments, cloned in an E. coli/C. glutamicum shuttle vector. Enzymatic analysis in C. glutamicum identified the dapA-complementing gene as l-2,3-dihydrodipicolinate synthetase (dapA), and the lysA-complementing gene as meso-diaminopimelate decarboxylase (lysA). In contrast, complementation of E. coli dapD8, presumably lacking L-Δ1-tetrahydrodipicolinate synthetase (dapD), led us to clone a diaminopimelate-lysine anabolic gene of C. glutamicum which does not exist in E. coli: meso-diaminopimelate dehydrogenase. Although meso-diaminopimelate is crucial in lysine formation and in cell wall biosynthesis, expression of the genomic copies of the cloned genes, which encode activities involved at key branching points of the diaminopimelate-lysine pathway of C. glutamicum, appears constitutive with regard to the addition of diaminopimelate and/or lysine during cell growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00322451
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  • 2
    Electronic Resource
    Electronic Resource
    Nucleotide sequence of the lysA gene of Corynebacterium glutamicum and possible mechanisms for modulation of its expression (1988)
    Springer
    Molecular genetics and genomics 212 (1988), S. 112-119 
    Details
    ISSN: 1617-4623
    Keywords: Corynebacterium glutamicum ; lysA promoter(s) ; Weak expression ; Full expression ; Bacterial evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sequence analysis localized the lysA gene of Corynebacterium glutamicum strain AS019 within a 1.35 kb open reading frame, potentially encoding a 445 amino acid product. Immediately downstream from this gene we found a potential ρ-independent transcription terminator, while the 5′ flanking region (300 bp) harbors unusual topological and structural features, located in the vicinity of a potential ribosome binding site. Within this upstream region, enzymatic and genetic analyses indicated the occurrence of a promoter responsible for significant, although weak, expression of the encoded enzymatic activity. The same significant expression level was observed with a plasmid harboring an additional 0.5 kb of genomic information upstream from lysA, while its full expression apparently requires 2 kb of additional genomic information located immediately upstream from the cloned gene. The upstream sequence requirement apparently associated with the full expression of the lysA gene of C. glutamicum shows some similarity with the Escherichia coli system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00322452
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  • 3
    Electronic Resource
    Electronic Resource
    The phosphoenolpyruvate carboxylase gene of Corynebacterium glutamicum: Molecular cloning, nucleotide sequence, and expression (1989)
    Springer
    Molecular genetics and genomics 218 (1989), S. 330-339 
    Details
    ISSN: 1617-4623
    Keywords: Corynebacterium glutamicum ; Phosphoenolpyruvate carboxylase ; ppc gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ppc gene of Corynebacterium glutamicum encoding phosphoenolpyruvate (PEP) carboxylase was isolated by complementation of a ppc mutant of Escherichia coli using a cosmid gene bank of chromosomal c. glutamicum DNA. By subsequent subcloning into the plasmid pUC8 and deletion analysis, the ppc gene could be located on a 3.3 kb SalI fragment. This fragment was able to complement the E. coli ppc mutant and conferred PEP carboxylase activity to the mutant. The complete nucleotide sequence of the ppc gene including 5′ and 3′ flanking regions has been determined and the primary structure of PEP carboxylase was deduced. The sequence predicts a 919 residue protein product (molecular weight of 103154) which shows 34% similarity with the respective E. coli enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331286
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  • 4
    Electronic Resource
    Electronic Resource
    Unique qualities and special problems of the African Great Lakes (1986)
    Springer
    Environmental biology of fishes 17 (1986), S. 161-183 
    Details
    ISSN: 1573-5133
    Keywords: Meromictic ; Evolution ; Diversity ; Cichlidae ; Productivity ; Aquatic reserves ; Flushing ; Pollution ; Fish introductions ; Lake development ; Limnology ; Fishery management ; Conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The African Great Lakes consist of large, deep rift valley lakes (e.g. Malawi & Tanganyika) and shallower lakes between the Eastern and Western Rifts (e.g. Victoria). They are a group comparable in size to the North American Great Lakes, but are old. Most are seasonally thermally stratified, and wind is the decisive factor that determines the annual cycle of cooling and mixing. Lakes Tanganyika, Malawi and Kivu are meromictic, with deep relict hypolimnia. Large magnitudes and time scales of periodic internal motion, where these have been measured, appear unique among lakes. These lakes harbour the world's richest lacustrine fish faunas, and the family Cichlidae provides the supreme example of geographically circumscribed vertebrate evolution. The lakes provide a unique comparative series of natural laboratories for evolutionary studies. Primary production is generally high, but in the deeper lakes standing stocks of plankton and of small fish species are low. These pelagic populations are characterised by very high P:B ratios. The fisheries are productive and of socio-economic importance. Large-scale mechanised fishing is not compatible with the survival of the diverse fish communities. Cichlids appear especially vulnerable to unselective fishing. Aquatic reserves might offer a means of survival for at least some communities. Various pollution threats exist. Because water retention times are long, extremely long for some deep lakes, and flushing rates are low, the lakes are vulnerable to pollution which would be long-lasting. Introductions of alien fishes have mostly had undesirable or disastrous results. While the faunas are one of the significant natural heritages of mankind, their conservation must realistically be linked to the legitimate development of the lakes for the well-being of the people who live there. Scientific value alone will not protect the lakes. Just as survival of African terrestrial wildlife in extensive reserves depends heavily upon tourism, so also might the cichlid flocks in underwater reserves. Greater interest from the international scientific community is needed to further rational development and conservation of these great lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002094
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  • 5
    Electronic Resource
    Electronic Resource
    Unique qualities and special problems of the African Great Lakes (1986)
    Springer
    Environmental biology of fishes 17 (1986), S. 161-183 
    Details
    ISSN: 1573-5133
    Keywords: Meromictic ; Evolution ; Diversity ; Cichlidae ; Productivity ; Aquatic reserves ; Flushing ; Pollution ; Fish introductions ; Lake development ; Limnology ; Fishery management ; Conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The African Great Lakes consist of large, deep rift valley lakes (e.g. Malawi & Tanganyika) and shallower lakes between the Eastern and Western Rifts (e.g. Victoria). They are a group comparable in size to the North American Great Lakes, but are old. Most are seasonally thermally stratified, and wind is the decisive factor that determines the annual cycle of cooling and mixing. Lakes Tanganyika, Malawi and Kivu are meromictic, with deep relict hypolimnia. Large magnitudes and time scales of periodic internal motion, where these have been measured, appear unique among lakes. These lakes harbour the world's richest lacustrine fish faunas, and the family Cichlidae provides the supreme example of geographically circumscribed vertebrate evolution. The lakes provide a unique comparative series of natural laboratories for evolutionary studies. Primary production is generally high, but in the deeper lakes standing stocks of plankton and of small fish species are low. These pelagic populations are characterised by very high P:B ratios. The fisheries are productive and of socio-economic importance. Large-scale mechanised fishing is not compatible with the survival of the diverse fish communities. Cichlids appear especially vulnerable to unselective fishing. Aquatic reserves might offer a means of survival for at least some communities. Various pollution threats exist. Because water retention times are long, extremely long for some deep lakes, and flushing rates are low, the lakes are vulnerable to pollution which would be long-lasting. Introductions of alien fishes have mostly had undesirable or disastrous results. While the faunas are one of the significant natural heritages of mankind, their conservation must realistically be linked to the legitimate development of the lakes for the well-being of the people who live there. Scientific value alone will not protect the lakes. Just as survival of African terrestrial wildlife in extensive reserves depends heavily upon tourism, so also might the cichlid flocks in underwater reserves. Greater interest from the international scientific community is needed to further rational development and conservation of these great lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698196
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  • 6
    Electronic Resource
    Electronic Resource
    African lakes and their fishes: conservation scenarios and suggestions (1987)
    Springer
    Environmental biology of fishes 19 (1987), S. 3-26 
    Details
    ISSN: 1573-5133
    Keywords: Captive propagation ; Extinction ; Genetic variability ; Evolution ; Speciation ; Lates niloticus ; Nile perch ; Haplochromines ; Tilapia ; Clupeids ; Oil pollution ; Productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Man has been associated with a variety of lakes throughout his evolutionary history in Africa. Lakeside dwellers have a close association with and understanding of these lakes. In the past four decades, however, overexploitation, introductions of alien fishes and the possibility of oil pollution present frightening prospects of irreversible losses and massive extinction. The development of scientific understanding of the life support processes, the ecosystems and the rich communities of these lakes has been so outpaced by exploitation and manipulations that accurate predictions regarding the future are impossible. Shallow lakes are more sensitive to physico-chemical changes caused by climatic as well as agricultural and industrial development than deep lakes, but their biotae are endowed with a resilience which facilitates recovery from major depletions to population size. In contrast, the speciose endemic cichlid faunae of deep lakes are sensitive to fishing pressure, are awkward to manage and should be regarded as representing a much smaller resource than initially imagined. The clupeids of Lake Tanganyika can sustain intensive fishing, but their introduction into other natural lakes is not recommended. Enormous changes to native faunae followed the introduction of Lates niloticus to lakes Kyoga and Victoria with dramatic consequences for the fisheries, for the socio-economic status of the region and for the maintenance of biotic diversity. Extinction of almost 300 fish species is a possible further consequence of L. niloticus predation. Intensive selective fishing for L. niloticus is being initiated, but is unlikely to resolve the problem. In the time necessary to substantially reduce L. niloticus, numerous endemic fishes may suffer extinction. A viable alternative to extinction of these species is captive propagation. Conservation of fishes by captive propagation is not a common or well documented practice. To encourage the acceptance of this conservation option a theoretical scenario in which the concepts and protocols are applied to the fishes of Lake Victoria is given. The possibility of returning rescued populations to the lake at a later date, assuming L. niloticus populations have been reduced, is also discussed. It is recommended that captive propagation should be practised to conserve species and to retain the option of returning rescued taxa. Scientists are urged to seek the funding to study tropical ecosystems so that conservation and rational development may acquire a sound foundation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002733
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  • 7
    Electronic Resource
    Electronic Resource
    Purification and properties of oxaloacetate decarboxylase fromCorynebacterium glutamicum (1995)
    Springer
    Antonie van Leeuwenhoek 67 (1995), S. 221-227 
    Details
    ISSN: 1572-9699
    Keywords: lysine biosynthesis ; aspartate-derived amino acids ; oxaloacetate decarboxylase ; pyruvate kinase ; Corynebacterium glutamicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oxaloacetate (OAA) decarboxylase (E.C. 4.1.1.3) was isolated fromCorynebacterium glutamicum. In five steps the enzyme was purified 300-fold to apparent homogeneity. The molecular mass estimated by gel filtration was 118 ± 6 kDa. SDS-PAGE showed a single subunit of 31.7 KDa, indicating an α4 subunit structure for the native enzyme. The enzyme catalyzed the decarboxylation of OAA to pyruvate and CO2, but no other α-ketoacids were used as substrate. The cation Mn2+ was required for full activity, but could be substituted by Mg2+, Co2+, Ni2+ and Ca2+. Monovalent ions like Na+, K+ or NH 4 + were not required for activity. The enzyme was inhibited by Cu2+, Zn2+, ADP, coenzyme A and succinate. Avidin did not inhibit the enzyme activity, indicating that biotin is not involved in decarboxylation of OAA. Analysis of the kinetic properties revealed a K m for OAA of 2.1 mM and a K m of 1.2 mM for Mn2+. The V max was 158 µmol of OAA converted per min per mg of protein, which corresponds to an apparent k cat of 311 s−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00871217
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  • 8
    Electronic Resource
    Electronic Resource
    Alternative life-history styles of some African cichlid fishes (1990)
    Springer
    Environmental biology of fishes 28 (1990), S. 87-100 
    Details
    ISSN: 1573-5133
    Keywords: Evolution ; Speciation ; Stabilizing selection ; Mbuna ; Cyrtocara ; Mouthbrooding ; Mate recognition ; Haplochromine ; Tilapiine ; Cuckoo ; Parental care ; Co-operative care
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis About 50% of African cichlid species have been described. Little is known about cichlid ecology, behaviour or about the evolution and interactions of communities. Nevertheless, trends which provide an insight into cichlid life histories, into evolutionary alternatives and into behavioural alternatives which may be followed during the life time of these fishes are emerging. Cichlids which spend their entire life history in a single habitat belong to species flocks that have spectated greatly. In contrast, those groups which live in a variety of habitats during their life history have spectated little. Despite the trophic specializations that have occurred among cichlids, many and perhaps all species, have the ability to feed upon alternative food resources. They do so by switching or by markedly modifying their behaviour and all are particularly opportunistic. The extensive adaptive radiation of cichlids with regard to those attributes of morphology and behaviour that are associated with survival and growth, is apparently not matched by similar radiations in reproductive behaviour. The perceived evolutionary conservatism with regard to reproductive behaviour is attributed to the effects of stabilizing selection, but this still needs to be tested. The constraints of stabilizing selection appear to be lifted with regard to coloration. If colour is an important component of the specific-mate recognition system then it should also be subjected to stabilizing selection so the readiness with which colour variation occurs within and between populations needs explanation. Parental care in cichlids has followed a variety of evolutionary alternatives, all of which are geared to improve the chances of survival of offspring in their specific micro-habitats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00751029
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  • 9
    Electronic Resource
    Electronic Resource
    Reaktionen an Indolderivaten, XI. Die stereoselektive Totalsynthese von DL-Ajmalicin, DL-19-epi-Ajmalicin, DL-Formosanin und Isoformosanin (1969)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 3558-3572 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ausgehend vom ungesättigten Keton 1 gelingt die stereoselektive Totalsynthese mehrerer heterocyclischer Indol- und Oxindol-Alkaloide. Speziell der stereoselektive Aufbau der C-19-Konfiguration sowie der Einfluß dieses Zentrums auf die Folgereaktionen werden diskutiert. Die Massenspektren der verschiedenen stereoisomeren Zwischenprodukte werden gegenübergestellt.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19691021034
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  • 10
    Electronic Resource
    Electronic Resource
    Auf der Suche nach Stabilen Carbenen (1998)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 32 (1998), S. 6-14 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article follows a thread through the history of the quest for stable carbenes. The story begins in 1835 with the attempts by Dumas to dehydrate methanol to produce methylene. It continues through modern times to a point where the accumulation of many false starts in stable carbene synthesis led to the conventional wisdom that carbenes are so highly reactive that they exist only as labile, short-lived molecules. The report of the isolation of the first stable crystalline carbene in 1991 began a renaissance in the chemistry of isolable carbenes. Much of the older chemistry is currently being revisited and reinterpreted with the aid of modern analytical techniques. Easily handled carbenes are opening many new opportunities in both exploratory chemistry and industrial applications.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19980320103
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