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1.
Y Ma B I Wilson S Bijvoet H E Henderson E Cramb G Roederer M R Ven Murthy P Julien H D Bakker J J Kastelein 《Genomics》1992,13(3):649-653
We have previously reported two common lipoprotein lipase (LPL) gene mutations underlying LPL deficiency in the majority of 37 French Canadians (Monsalve et al., 1990. J. Clin. Invest. 86: 728-734; Ma et al., 1991. N. Engl. J. Med. 324: 1761-1766). By examining the 10 coding exons of the LPL gene in another French Canadian patient, we have identified a third missense mutation that is found in two of the three remaining patients for whom mutations are undefined. This is a G to A transition in exon 6 that results in a substitution of asparagine for aspartic acid at residue 250. Using in vitro site-directed mutagenesis, we have confirmed that this mutation causes a catalytically defective LPL protein. In addition, the Asp250----Asn mutation was also found on the same haplotype in an LPL-deficient patient of Dutch ancestry, suggesting a common origin. This mutation alters a TaqI restriction site in exon 6 and will allow for rapid screening in patients with LPL deficiency. 相似文献
2.
S.M. Loh A. Raya D.S. Cramb L.E. O'Gorman R.A. Skurray 《FEMS microbiology letters》1986,37(2):179-182
Abstract The leading region of the F plasmid has been found to extend the maintenance of the normally unstable plasmid vector pACYC184. This ability is due to effective partitioning of plasmid molecules at cell division. Cloning, deletion analysis and transposon mutagenesis have located the partitioning region (ParL) to be encoded within 63.65–64.11F. Complementation studies indicated that parL is a cis -acting locus. 相似文献
3.
Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews
(genus Sorex) for the region between the tRNA(Pro) and the conserved
sequence block-F revealed variable numbers of 79-bp tandem repeats. These
repeats were found in all 19 individuals sequenced, representing three
subspecies and one closely related species of the masked shrew group (Sorex
cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an
outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an
adjacent 76-bp imperfect copy of the tandem repeats. One individual was
heteroplasmic for length variants consisting of five and seven copies of
the 79-bp tandem repeat. The sequence of the repeats is conducive to the
formation of secondary structure. A termination-associated sequence is
present in each of the repeats and in a unique sequence region 5' to the
tandem array as well. Mean genetic distance between the masked shrew taxa
and the pygmy shrew was calculated separately for the unique sequence
region, one of the tandem repeats, the imperfect repeat, and these three
regions combined. The unique sequence region evolved more rapidly than the
tandem repeats or the imperfect repeat. The small genetic distance between
pairs of tandem repeats within an individual is consistent with a model of
concerted evolution. Repeats are apparently duplicated and lost at a high
rate, which tends to homogenize the tandem array. The rate of D- loop
sequence divergence between the masked and pygmy shrews is estimated to be
15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid
sequence evolution in shrews may be due either to their high metabolic rate
and short generation time or to the presence of variable numbers of tandem
repeats.
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4.
Partial purification of two lithocholic acid-binding proteins from rat liver 100 000g supernatants. 总被引:5,自引:5,他引:0 下载免费PDF全文
1. The partial purification of two lithocholic acid-binding proteins from liver 100 000g supernatants is described. 2. Gel-filtration, (NH4)2SO4 fractionation, Ca3(PO4)2 fractionation and ion-exchange chromatography were used. 3. Both proteins exhibited glutathione S-transferase activity; one may be the non-specific anion-binding protein ligandin. 4. Glutathione S-transferase activity of one of the binding proteins was inhibited by lithocholic acid. 相似文献
5.
High voltage-activated (HVA) Cav channels form complexes with KCa1.1 channels, allowing reliable activation of KCa1.1 current through a nanodomain interaction. We recently found that low voltage-activated Cav3 calcium channels also create KCa1.1-Cav3 complexes. While coimmunoprecipitation studies again supported a nanodomain interaction, the sensitivity to calcium chelating agents was instead consistent with a microdomain interaction. A computational model of the KCa1.1-Cav3 complex suggested that multiple Cav3 channels were necessary to activate KCa1.1 channels, potentially causing the KCa1.1-Cav3 complex to be more susceptible to calcium chelators. Here, we expanded the model and compared it to a KCa1.1-Cav2.2 model to examine the role of Cav channel conductance and kinetics on KCa1.1 activation. As found for direct recordings, the voltage-dependent and kinetic properties of Cav3 channels were reflected in the activation of KCa1.1 current, including transient activation from lower voltages than other KCa1.1-Cav complexes. Substantial activation of KCa1.1 channels required the concerted activity of several Cav3.2 channels. Combined with the effect of EGTA, these results suggest that the Ca2+ domains of several KCa1.1-Cav3 complexes need to cooperate to generate sufficient [Ca2+]i, despite the physical association between KCa1.1 and Cav3 channels. By comparison, Cav2.2 channels were twice as effective at activating KCa1.1 channels and a single KCa1.1-Cav2.2 complex would be self-sufficient. However, even though Cav3 channels generate small, transient currents, the regulation of KCa1.1 activity by Cav3 channels is possible if multiple complexes cooperate through microdomain interactions. 相似文献
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7.
Cutler CP Cramb G 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2001,130(3):551-564
This review focuses on recent developments in the molecular biology of ion and water transporter genes in fish and the potential role of their products in osmoregulation in both freshwater and seawater environments. In particular details of isoforms of various ATPases, co-transporters, exchangers and ion channels in the eel as well as other teleost species are described. Many of the teleost transporter isoforms discovered so far, appear to occur as twin or duplicate copies compared to their homologous counterparts in higher vertebrates, although these duplicate isoforms often have distinct tissue-specific and developmental stage-dependent expression patterns. The possible meaning of this information will be examined in relation to the fish genome duplication debate. 相似文献
8.
Aravinthan DT Samuel Venkatesh N Murthy Michael O Hengartner 《BMC developmental biology》2001,1(1):8-6
Background
Of the animals typically used to study fertilization-induced calcium dynamics, none is as accessible to genetics and molecular biology as the model organism Caenorhabditis elegans. Motivated by the experimental possibilities inherent in using such a well-established model organism, we have characterized fertilization-induced calcium dynamics in C. elegans.Results
Owing to the transparency of the nematode, we have been able to study the calcium signal in C. elegans fertilization in vivo by monitoring the fluorescence of calcium indicator dyes that we introduce into the cytosol of oocytes. In C. elegans, fertilization induces a single calcium transient that is initiated soon after oocyte entry into the spermatheca, the compartment that contains sperm. Therefore, it is likely that the calcium transient is initiated by contact with sperm. This calcium elevation spreads throughout the oocyte, and decays monotonically after which the cytosolic calcium concentration returns to that preceding fertilization. Only this single calcium transient is observed.Conclusion
Development of a technique to study fertilization induced calcium transients opens several experimental possibilities, e.g., identification of the signaling events intervening sperm binding and calcium elevation, identifying the possible roles of the calcium elevation such as the completion of meiosis, the formation of the eggshell, and the establishing of the embryo's axis of symmetry. 相似文献9.
Tipsmark CK Madsen SS Seidelin M Christensen AS Cutler CP Cramb G 《The Journal of experimental zoology》2002,293(2):106-118
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