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  • 1
    Electronic Resource
    Electronic Resource
    Comparisons of the Nucleotide Substitution Process Among Repetitive Segments of the α- and β-Spectrin Genes (1997)
    Springer
    Journal of molecular evolution 44 (1997), S. 492 -500 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Spectrin — Substitution pattern — Substitution rate — Elliptocytosis — Spherocytosis — Maximum likelihood — Gene duplication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The actin–cross-linking protein spectrin is a prominent component of the membrane cytoskeleton. Spectrin is a tetramer of two antiparallel αβ-dimers which share a unique and ancient gene structure. The α-spectrin and β-spectrin genes are composed primarily of tandemly repeated 106-amino-acid segments, each of which forms a triple α-helical coiled coil. Both the genes and the repeats themselves are homologous. The two genes are thought to be the result of a gene duplication event, and each gene is the product of duplications of the 106-amino-acid repeats. In this work we compare the process of molecular evolution across the repeated segments of the α- and β-spectrin genes. We find that the α-spectrin segments have, for the most part, evolved in a homogeneous fashion, while considerable heterogeneity is found among β-spectrin segments. Several segments with unique known functions are found to have evolved differently than the others. On the basis of heterogeneity of the evolutionary process, we suggest that at least one repeat has a unique function that has yet to be documented. We also present new statistical methods for comparing the evolutionary process between different regions of DNA sequences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006173
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  • 2
    Electronic Resource
    Electronic Resource
    The Berlekamp-Massey algorithm and linear recurring sequences over a factorial domain (1995)
    Springer
    Applicable algebra in engineering, communication and computing 6 (1995), S. 309-323 
    Details
    ISSN: 1432-0622
    Keywords: Polynomial remainder sequence ; Berlekamp-Massey algorithm ; linear recurring sequence ; factorial domain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics , Technology
    Notes: Abstract We present an extended polynomial remainder sequence algorithm XPRS for R[X] whereR is a domain. From this we derive a Berlekamp-Massey algorithm BM/R overR. We show that if (α) is a linear recurring sequence in a factorial domainU, then the characteristic polynomials for (α) form aprincipal ideal which is generated by a primitive minimal polynomial. Moreover, this generator ismonic when U[[X]] is factorial (for example, whenU is Z orK[X 1,X2,...,Xn] whereK is a field). From XPRS we derive an algorithm MINPOL for determining the minimal polynomial of (α) when an upper bound on the degree of some characteristic polynomial and sufficiently many initial terms of (α) are known. We also show how to obtain a Berlekamp-Massey type minimal polynomial algorithm from BM/U and state BM_MINPOL/K explicitly with a further refinement. Examples are given forU=Z, GF(2)[Y].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01235722
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  • 3
    Electronic Resource
    Electronic Resource
    The Berlekamp-Massey Algorithm and Linear Recurring Sequences Over a Factorial Domain (1995)
    Springer
    Applicable algebra in engineering, communication and computing 6 (1995), S. 309-323 
    Details
    ISSN: 1432-0622
    Keywords: Keywords: Polynomial remainder sequence ; Berlekamp-Massey algorithm ; linear recurring sequence ; factorial domain.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics , Technology
    Notes: Abstract.  We present an extended polynomial remainder sequence algorithm XPRS for R[X] where R is a domain. From this we derive a Berlekamp-Massey algorithm BM/R over R. We show that if (α) is a linear recurring sequence in a factorial domain U, then the characteristic polynomials for (α) form a principal ideal which is generated by a primitive minimal polynomial. Moreover, this generator is monic when U[ [X] ] is factorial (for example, when U is Z or K[X 1 , X 2 , . . . , X n ] where K is a field). From XPRS we derive an algorithm MINPOL for determining the minimal polynomial of (α) when an upper bound on the degree of some characteristic polynomial and sufficiently many initial terms of (α) are known. We also show how to obtain a Berlekamp-Massey type minimal polynomial algorithm from BM/U and state BM – MINPOL/K explicitly with a further refinement. Examples are given for U = Z, GF(2) [Y ].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002000050008
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  • 4
    Electronic Resource
    Electronic Resource
    A classical dilemma (1995)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 102 (1995), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1995.tb11442.x
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  • 5
    Electronic Resource
    Electronic Resource
    The use of a new viability assay to determine the susceptibility of Cryptosporidium and Eimeria sporozoites to respiratory inhibitors and extremes of pH (1996)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 142 (1996), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A new viability assay for Cryptosporidium and Eimeria sporozoites is described. It involves the use of both acridine orange and bis-benzimide and is more rapid, easier and less subjective than procedures used previously. The assay has been used to investigate the effects of respiratory inhibitors and pH on the sporozoites of C. parvum, C. muris and E. tenella. Neither cyanide nor azide reduced the viability of C. parvum or E. tenella, whereas they had some effect on C. muris. This latter organism, an intracellular parasite of stomach epithelial cells, also differed from the other two in being able to survive pH 2 for as long as 1 h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1996.tb08431.x
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  • 6
    Electronic Resource
    Electronic Resource
    Enzymes of energy metabolism in the bradyzoites and tachyzoites of Toxoplasma gondii (1996)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 137 (1996), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The bradyzoite and tachyzoite forms of Toxoplasma gondii, purified from infected animals, were analysed for their activities of phosphofructokinase, pyruvate kinase, lactate dehydrogenase, NAD+- and NADH-linked isocitrate dehydrogenases, and succinic dehydrogenase. Both developmental stages contained high activities of phosphofructokinase (specific for pyrophosphate rather than ATP), pyruvate kinase and lactate dehydrogenase, suggesting that energy metabolism in both forms may centre around a high glycolytic flux linked to lactate production. The markedly higher activity of the latter two enzymes in bradyzoites suggests that lactate production is particularly important in this developmental form. NAD+-specific isocitrate dehydrogenase was not detectable in either stage of the parasite (and proved useful as a measure of the purity of the bradyzoite preparation), whereas both parasite forms contained low activities of NADP+-linked isocitrate dehydrogenase. The results are consistent with the bradyzoites lacking a functional TCA cycle and respiratory chain and are suggestive of a lack of susceptibility of this developmental stage to atovaquone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1996.tb08090.x
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  • 7
    Electronic Resource
    Electronic Resource
    Amino acid consumption by the parasitic, amoeboid protists Entamoeba histolytica and E. invadens (1995)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 130 (1995), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Amino acid consumption by Entamoeba histolytica and E. invadens has been measured in order to assess the possible roles of amino acids as energy substrates. Mixtures of amino acids enhanced the growth of the parasites in complex medium and their survival in simple medium. The consumption of several amino acids by the parasites suspended in simple media was greater when glucose was absent, suggesting that they may act as alternative energy sources. Under these conditions, asparagine was consumed extremely rapidly by E. histolytica in particular, and arginine, leucine and threonine were used greatly by both species. There was also a marked consumption of aspartate, but this occurred even when glucose was present. These five amino acids and phenylalanine were the ones consumed in greatest amounts during growth of E. histolytica in complex medium. Under the same growth conditions, E. invadens also used asparagine, arginine, leucine and threonine and in addition there was a large consumption of serine and especially glutamate. In contrast, the aspartate concentration in the complex medium increased and there was also a net increase in the concentration of some other amino acids. Alanine was produced by both species when the parasites were incubated in simple medium with glucose, and in greater amounts during growth in complex media, suggesting that it is an end product of energy metabolism. The findings provide support for the suggestion that energy generation through amino acid catabolism may be a characteristic feature of anaerobic parasitic protists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1995.tb07728.x
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  • 8
    Electronic Resource
    Electronic Resource
    Methane oxidation potential and preliminary analysis of methanotrophs in blanket bog peat using molecular ecology techniques (1996)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 21 (1996), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: The potential for methane oxidation was measured, and methanotroph gene sequences studied, in a peat core from the Moorhouse Nature Reserve, UK. Methane oxidation potential was observed in all depths of the peat core (down to 30 cm), and was inhibited by addition of acetylene, indicating the involvement of methane-oxidising bacteria. A peak of activity was shown in the 10–12 cm horizon, below which activity decreased with depth. Above this horizon, methane oxidation was relatively high and showed little change with depth. 16S rDNA libraries from several sections of the peat core were screened with methanotroph 16S rDNA probes designed to detect the genera Methylomonas, Methylococcus, Methylobacter and Methylosinus. Two clones, MHP14 and MHP17, hybridised strongly with the Methylosinus probe and upon complete sequencing and phylogenetic analysis were shown to group closely to the Methylosinus/Methylocystis genera of methanotrophs. However, the clones do form a distinct branch of their own, supported by BOOTSTRAP values, and may represent a novel group of acidophilic methanotrophs which have yet to be cultured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1996.tb00347.x
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  • 9
    Electronic Resource
    Electronic Resource
    Use of inhibitors to identify essential cysteine proteinases of Trichomonas vaginalis (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 149 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Designing cysteine proteinase inhibitors as antitrichomonal drugs requires knowledge of which cysteine proteinases are essential to the parasite. In an attempt to obtain such information, the effects of a number of cysteine proteinase inhibitors on trichomonad growth in vitro and proteinase activity were investigated. The broad specificity inhibitor trans-epoxysuccinyl-l-leucylamido-(4-guanidino)butane (known as E-64) had little effect on growth of Trichomonas vaginalis (27% inhibition at 280 μM, none at 28 μM) even though the addition of 2.8 μM E-64 to growth medium resulted in inhibition of all but two (apparent molecular masses: 35 k and 49 k) of the parasite's proteinases detected by gelatin SDS-PAGE. This shows that many of the parasite's cysteine proteinases are not essential for growth in axenic culture. In contrast, a peptidyl acyloxymethyl ketone, N-benzoyloxycarbonyl-Phe-Ala-CH2OCO-(2,6,-(CF3)2)Ph, at 16 μM killed T. vaginalis and severely inhibited growth of Tritrichomonas foetus. Exposure of Trichomonas vaginalis to 16 μM of this compound for 1 h resulted in both the 35 kDa and 49 kDa proteinases being inhibited, whereas some other proteinases were unaffected. Similar distinctions between the inhibitor sensitivity of the parasite's cysteine proteinases were apparent when a biotinylated peptidyl diazomethyl ketone was used to detect active proteinases. These data suggest that the growth inhibitory effects of the peptidyl acyloxymethyl ketone are through inhibition of cysteine proteinases that are not affected when the parasites are grown in the presence of E-64. At least one of these enzymes, which include the 35 kDa and 49 kDa cysteine proteinases, must be essential and so a suitable target for chemotherapeutic attack.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb10306.x
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  • 10
    Electronic Resource
    Electronic Resource
    Evidence for the shikimate pathway in apicomplexan parasites (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 393 (1998), S. 801-805 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Parasites of the phylum Apicomplexa cause substantial morbidity, mortality and economic losses, and new medicines to treat them are needed urgently,. The shikimate pathway is an attractive target for herbicides and antimicrobial agents because it is essential in algae, higher plants, bacteria ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/31723
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