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1.
Phylogeny and rapid Northern and Southern Hemisphere speciation of goldfinches during the Miocene and Pliocene Epochs 总被引:5,自引:0,他引:5
A. Arnaiz-Villena M. Álvarez-Tejado V. Ruíz-del-Valle C. García-de-la-Torre P. Varela M. J. Recio S. Ferre J. Martínez-Laso 《Cellular and molecular life sciences : CMLS》1998,54(9):1031-1041
Mitochondrial cytochrome b (cyt b) from 25 out of 31 extant goldfinches, siskins, greenfinches and redpolls (genus Carduelis) has been sequenced from living samples taken around the world, specimens have also been photographed. Phylogenetic analysis
consistently gave the same groups of birds, and this grouping was generally related to geographical proximity. It has been
supposed that Pleistocene glaciations played a crucial role in the origin of extant diversity and distribution of Northern
Hemisphere vertebrates. Molecular comparison of most extant songbird species belonging to the genus Carduelis does not support this assertion. The fossil record of chicken and pheasant divergence time has been used to calibrate the
molecular clock; cyt b DNA dendrograms suggest that speciation in Carduelinae birds occurred during the Miocene and Pliocene
Epochs (9 – 2 million years ago) in both the Northern and Southern Hemispheres. Only about 4% average amount of nucleotide
substitution per lineage is found between the most distant Carduelis species; this suggests a remarkably rapid radiation when compared with the radiation of other passerine songbird genera.
In addition, a continuum of small songbird speciation may be found during the Miocene Epoch in parallel with speciation of
other orders (i.e. Galliformes, chicken/pheasant). Pleistocene glaciations may have been important in subspeciation (i.e.
Eastern European grey-headed goldfinches/Western European black-headed goldfinches) and also in ice-induced vicariance (isolation)
(i.e. siskin in Western Europe vs. siskin in Far East Asia) around the world. European isolated Serinus citrinella (citril finch) is not a canary, but a true goldfinch. South American siskins have quickly radiated in the last 4 million
years coinciding with the emergence of the Isthmus of Panama; probably, a North American siskin related to C. notata invaded a suitable and varied biotope (the South American island) for Carduelis birds. North American goldfinches may be renamed as siskins, because they have a distant genetic relationship with European
goldfinches. Genus Acanthis could be dropped, and thus redpolls should be separated from twite and linnet, the latter (Europeans) probably being related
to American goldfinches. Also, reproductive barriers are observed between closely related species and not between other more
distant ones. Finally, a tentative classification for genus Carduelis species is suggested.
Received 6 March 1998; received after revision 3 July 1998; accepted 7 July 1998 相似文献
2.
Evidence of undiscovered cell regulatory mechanisms: phosphoproteins and protein kinases in mitochondria 总被引:3,自引:0,他引:3
Thomson M 《Cellular and molecular life sciences : CMLS》2002,59(2):213-219
The finding that mitochondria contain substrates for protein kinases lead to the discovery that protein kinases are located
in the mitochondria of certain tissues and species. These include pyruvate dyhydrogenase kinase, branched-chain α-ketoacid dehydrogenase kinase, protein kinase A, protein kinase Cδ, stress-activated kinase and A-Raf as well as unidentified kinases. Recent evidence suggests that mitochondrial protein kinases
may be involved in physiological processes such as apoptosis and steroidogenesis. Additionally, the novel finding of low-molecular-weight
GTP-binding proteins in mitochondria suggests the possibility that these may interact with mitochondrial protein kinases to
regulate the activity of mitochondrial effector proteins. The fact that there are components of cellular regulatory systems
in mitochondria indicates the exciting possibility of undiscovered systems regulating mitochondrial physiology.
Received 19 June 2001; received after revision 7 August 2001; accepted 8 August 2001 相似文献
3.
Allometry of mammalian cellular oxygen consumption 总被引:3,自引:0,他引:3
R.K. Porter 《Cellular and molecular life sciences : CMLS》2001,58(5-6):815-822
In the 1930s, Max Kleiber and Samuel Brody established that the interspecies correlation between mammalian body mass and
metabolic rate (αM0.75) cannot be explained (solely) by whole body surface area (αM0.66) to volume ratios. Metabolic considerations must also be taken into account. Decreases in the proportion of visceral organ
mass to whole body mass can account for some of the whole body metabolic differences. However, superimposed upon these anatomical
differences, the metabolism of tissues and cells has been demonstrated to decrease with increasing body mass. These decreases
in oxygen consumption rates (with increasing body mass) in cells and tissues can be explained by a decrease in ATP turnover
and mitochondrial density and an increase in mitochondrial functional efficiency (decrease in proton leak). The majority of
the proton leak differences reflect differences in mitochondrial inner membrane surface area. Indeed, liver metabolism correlates
directly with liver mitochondrial inner membrane surface area. Apart from being a significant contributor (~25 %) to basal
metabolism, mitochondrial proton leak is a major factor determining the differences in basal metabolism between mammals of
different body mass.
Received 31 May 2000; received after revision 2 October 2000; accepted 14 November 2000 相似文献
4.
Prosperi-Meys C Wouters J Galleni M Lamotte-Brasseur J 《Cellular and molecular life sciences : CMLS》2001,58(14):2136-2143
Increased resistance to β-lactam antibiotics is mainly due to β-lactamases whose production by pathogenic bacteria makes their broad activity spectrum
especially frightening. X-ray structures of several zinc β-lactamases have revealed the coordination of the two metal ions, but their mode of action remains unclear. Geometry optimisation
of stable complexes along the reaction pathway of benzylpenicillin hydrolysis highlighted a proton shuttle occurring from
D120 of the Bacillus cereus β-lactamase to the β-lactam nitrogen via Zn2 which is central to the network. First, the Zn1 ion has a structural role maintaining Zn-bound waters,
WAT1 and WAT2, either directly or through the Zn1 tetrahedrally coordinated histidine ligands. The Zn2 ion has a more catalytic
role, stabilising the tetrahedral intermediate, accepting the β-lactam nitrogen atom as a ligand. The role of Zn2 and the flexibility in the coordination geometry of both Zn ions is of
crucial importance for catalysis.
Received 14 August 2001; received after revision 19 October 2001; accepted 30 October 2001 相似文献
5.
G-protein signaling: back to the future 总被引:14,自引:0,他引:14
McCudden CR Hains MD Kimple RJ Siderovski DP Willard FS 《Cellular and molecular life sciences : CMLS》2005,62(5):551-577
Heterotrimeric G-proteins are intracellular partners of G-protein-coupled receptors (GPCRs). GPCRs act on inactive G·GDP/G heterotrimers to promote GDP release and GTP binding, resulting in liberation of G from G. G·GTP and G target effectors including adenylyl cyclases, phospholipases and ion channels. Signaling is terminated by intrinsic GTPase activity of G and heterotrimer reformation – a cycle accelerated by regulators of G-protein signaling (RGS proteins). Recent studies have identified several unconventional G-protein signaling pathways that diverge from this standard model. Whereas phospholipase C (PLC) is activated by Gq and G, novel PLC isoforms are regulated by both heterotrimeric and Ras-superfamily G-proteins. An Arabidopsis protein has been discovered containing both GPCR and RGS domains within the same protein. Most surprisingly, a receptor-independent G nucleotide cycle that regulates cell division has been delineated in both Caenorhabditis elegans and Drosophila melanogaster. Here, we revisit classical heterotrimeric G-protein signaling and explore these new, non-canonical G-protein signaling pathways.Received 21 October 2004; received after revision 20 November 2004; accepted 30 November 2004 相似文献
6.
J. Schaller U. Kämpfer S. Schürch L. Kuhn-Nentwig S. Haeberli W. Nentwig 《Cellular and molecular life sciences : CMLS》2001,58(10):1538-1545
CSTX-9 (68 residues, 7530.9 Da) is one of the most abundant toxic polypeptides in the venom of the wandering spider Cupiennius salei. The amino acid sequence was determined by Edman degradation using reduced and alkylated CSTX-9 and peptides generated by
cleavages with endoproteinase Asp-N and trypsin, respectively. Sequence comparison with CSTX-1, the most abundant and the
most toxic polypeptide in the crude spider venom, revealed a high degree of similarity (53% identity). By means of limited
proteolysis with immobilised trypsin and RP-HPLC, the cystine-containing peptides of CSTX-9 were isolated and the disulphide
bridges were assigned by amino acid analysis, Edman degradation and nanospray tandem mass spectrometry. The four disulphide
bonds present in CSTX-9 are arranged in the following pattern: 1-4, 2-5, 3-8 and 6-7 (Cys6-Cys21, Cys13-Cys30, Cys20-Cys48, Cys32-Cys46). Sequence comparison of CSTX-1 with CSTX-9 clearly indicates the same disulphide bridge pattern, which is also found in
other spider polypeptide toxins, e.g. agatoxins (ω-AGA-IVA, ω-AGA-IVB, μ-AGA-I and μ-AGA-VI) from Agelenopsis aperta, SNX-325 from Segestria florentina and curtatoxins (CT-I, CT-II and CT-III) from Hololena curta. CSTX-1/CSTX-9 belong to the family of ion channel toxins containing the inhibitor cystine knot structural motif. CSTX-9,
lacking the lysine-rich C-terminal tail of CSTX-1, exhibits a ninefold lower toxicity to Drosophila melanogaster than CSTX-1. This is in accordance with previous observations of CSTX-2a and CSTX-2b, two truncated forms of CSTX-1 which,
like CSTX-9, also lack the C-terminal lysine-rich tail.
Received 23 July 2001; accepted 31 July 2001 相似文献
7.
Johansson S Gullbo J Lindholm P Ek B Thunberg E Samuelsson G Larsson R Bohlin L Claeson P 《Cellular and molecular life sciences : CMLS》2003,60(1):165-175
Four novel proteins (phoratoxins C–F) have been isolated from the North American mistletoe Phoradendron tomentosum. The amino acid sequences of these phoratoxins were determined unambiguously using a combination of Edman degradation and
trypsin enzymatic digestion, and by electrospray ionization tandem mass spectrometry sequencing. Phoratoxins C, E and F consist
of 46 amino acid residues; and phoratoxin D of 41. All proteins had six cysteines, similar to the earlier described phoratoxins
A and B, which are thionins. The cytotoxicity of each protein was evaluated in a human cell line panel that represented several
cytotoxic drug-resistance mechanisms. For the half-maximal inhibitory concentrations (IC50 values) of the different cell lines in the panel, correlation with those of standard drugs was low. The most potent cytotoxic
phoratoxin C was further tested on primary cultures of human tumor cells from patients. The solid tumor samples from breast
cancer cells were 18 times more sensitive to phoratoxin C than the tested hematological tumor samples.
Received 30 September 2002; received after revision 28 October 2002; accepted 7 November 2002
RID="*"
ID="*"Corresponding author. 相似文献
8.
Jurka J 《Cellular and molecular life sciences : CMLS》2008,65(2):201-204
Multiple remnants of transposable elements preserved in cis-regulatory modules may represent a record of mutations that were critical to the evolution of gene regulation and speciation.
Received 13 August 2007; received after revision 8 October 2007; accepted 23 October 2007 相似文献
9.
Mitochondrial dysfunction and protein kinase C (PKC) activation are consistently found in diabetic cardiomyopathy but their
relationship remains unclear. This study identified mitochondrial aconitase as a downstream target of PKC activation using
immunoblotting and mass spectrometry, and then characterized phosphorylation-induced changes in its activity in hearts from
type 1 diabetic rats. PKCβ2 co-immunoprecipitated with phosphorylated aconitase from mitochondria isolated from diabetic hearts. Augmented phosphorylation
of mitochondrial aconitase in diabetic hearts was found to be associated with an increase in its reverse activity (isocitrate
to aconitate), while the rate of the forward activity was unchanged. Similar results were obtained on phosphorylation of mitochondrial
aconitase by PKCβ2 in vitro. These results demonstrate the regulation of mitochondrial aconitase activity by PKC-dependent phosphorylation. This may
influence the activity of the tricarboxylic acid cycle, and contribute to impaired mitochondrial function and energy metabolism
in diabetic hearts.
Received 31 October 2008; received after revision 17 December 2008; accepted 2 January 2009 相似文献
10.
Apaf1 has been described as the core of the apoptosome. Deficiency in murine Apaf1 leads to embryonic lethality with a phenotype affecting many aspects of developmental apoptosis. In the developing brain,
Apaf1 is a death regulator of the neuronal founder cells. Combined intercrosses of mouse lines mutant for members of the mitochondrial
death pathway are providing us with some clues about the relative regulation existing among neuronal cell populations. Apaf1-deficient embryos display an interesting phenotype in the inner ear and in limb development, which involves different caspase-dependent
and -independent pathways. Moreover, APAF1 is mutated in human melanomas, and its depletion contributes to malignant transformation in a mouse model of cancer. This
review has a double aim: the analysis of the alternatives taken by the embryo to bring into the suicidal program different
cells at different stages, and the relevance of APAF1 in the onset and progression of cancer.
Received 5 March 2001; received after revision 19 April 2001; accepted 4 May 2001 相似文献
11.
Cellulase genes of Pseudotrichonympha grassii (Hypermastigida: Eucomonymphidae), the symbiotic flagellate in the hindgut of the wood-feeding termite Coptotermes formosanus, were isolated and characterized. The nucleotide sequences of the major cellulase component in the hindgut of C. formosanus were determined based on its N-terminal amino acid sequence. The five isolated nucleotide sequences (PgCBH-homos) had an open reading frame of 1350 bp showing similarity to catalytic domains of glycoside hydrolase family (GHF) 7 members,
and primary structure comparison with GHF7 members whose tertiary structures are well-characterized revealed the overall similarity
between PgCBH-homo and the catalytic domain of a processive cellulase Cel7A (formerly CBHI) from the aerobic fungus Trichoderma reesei. Functional expression of PgCBH-homos in Escherichia coli, using the carboxymethylcellulose-Congo red assay, demonstrated the actual cellulolytic activity of PgCBH-homo. RT-PCR showed
that PgCBH-homos were expressed, from the three flagellates in the hindgut, specifically in P. grassii.
Received 10 July 2002; accepted 26 July 2002
RID="*"
ID="*"Corresponding author. 相似文献
12.
Twelve cosmids containing sequences resembling genes encoding members of the 70-kDa heat-shock protein family, HSP70, have
been isolated from Fugu rubripes. They can be broadly divided into three groups of overlapping cosmids. Restriction analysis and sequencing of one set of
five cosmids have revealed five intronless Fugu HSP70 genes spanning 42 kb, arranged in a combined head-to-head, tail-to-tail and head-to-tail orientation. The levels of DNA and
amino acid identity are very high with respect to one another, and are most similar to HSP70 sequences linked to the major histocompatibility complex (MHC) region in other species. Putative heat-shock consensus elements
are identified. Non-HSP70 sequences with homology to known genes have been found physically linked to this Fugu HSP70 cluster: the Drosophila melanogaster
SOL gene, the Drosophila melanogaster nemo gene, the Caenorhabditis elegans T17E9.1 gene and the sequence encoding the serine protease domain. The linkage relationships described here so far bear no resemblance
to those of HSP70 in other organisms. Convergence of mammalian HSP70 and MHC class I and II loci probably occurred after fish had diverged.
Received 17 November 1998; received after revision 25 February 1999; accepted 26 February 1999 相似文献
13.
Arnaiz-Villena A Guillén J Ruiz-del-Valle V Lowy E Zamora J Varela P Stefani D Allende LM 《Cellular and molecular life sciences : CMLS》2001,58(8):1159-1166
Mitochondrial cytochrome b (cyt b) from 24 Carduelini species including crossbills, bullfinches, grosbeaks, rosefinches, and other related, but not conclusively classified species, was sequenced. These sequences were also compared with all the available sequences from the genera Carduelis, Serinus, and Passer. Phylogenetic analyses consistently gave the same groups of finches and the calculated divergence times suggest that speciation of the studied species occurred between 14 and 3 million years ago (Miocene-Pliocene), appearing before the Passer, Carduelis, and Serinus genera. Pleistocene glaciations may have been important in sub-speciation. Crossbills are integrated within the genus Carduelis, and within redpolls; the common crossbill shows subspeciation with Loxia japonica in the Pleistocene epoch. Pinicola enucleator groups together with bullfinches and is probably the ancestor of the group. Hawfinch is only distantly related to the studied groups, and might either represent an isolated genus or be related to the New World genus Hesperiphona. The grosbeak genera Eophona and Mycerobas are clearly sister groups, and species belonging to the former might have given rise to Mycerobas species. The isolated (in classification) Uragus sibiricus and Haematospiza sipahi are included within the genus Carpodacus (rosefinches); Carpodacus nipalensis is outside the genus Carpodacus in the molecular analyses and might be an isolated species or related to the genus Montifringilla. 相似文献
14.
An anti-Bcl-2 antibody prevents 2-deoxy-D-ribose-induced apoptosis in the IPLB-LdFB insect cell line
Barbieri D Malagoli D Cuoghi B Ottaviani E 《Cellular and molecular life sciences : CMLS》2001,58(4):653-659
Confocal microscopy reveals that the anti-Bcl-2 antibody (pAb) is able to diffuse across the plasma membrane of the fat body
cell line IPLB-LdFB from the insect Lymantria dispar, demonstrating the presence of Bcl-2-like molecules in the cytoplasm. Immunoperoxidase procedure confirms the cellular localization.
Furthermore, an immunoprecipitation corresponding to a molecular weight of 29 KDa is observed with western blot analysis using
the anti-Bcl-2 pAb. Cytofluorimetric experiments show that anti-Bcl-2 pAb counteracts 2-deoxy-d-ribose-induced apoptosis and provokes morphological changes in the insect cell line, i.e. a reduction in cell size, the disappearance
of the vacuola and changes in shape. At the same time, the antibody provokes mitochondrial membrane depolarization, and N-acetyl-l-cysteine is unable to reconstitute the physiological conditions. The present findings suggest that Bcl-2-like proteins play
a main role in maintaining of the integrity of cellular components, e.g. mitochondria, rather than in controlling programmed
cell death.
Received 23 January 2001; received after revision 1 March 2001; accepted 1 March 2001 相似文献
15.
M. Sedqi M. Delaforge D. Mansuy B. Martin P. Jollès D. Migliore-Samour 《Cellular and molecular life sciences : CMLS》1995,51(8):790-798
The sex-dependent effect of lauroyl-L-Ala-D--Glu-L,L-A2pmNH2 (LtriP, RP 56142) on hepatic microsomal cytochromes P 450 (cyt P 450) was studied in three mouse strains NMRI, C3H/OuJ and C3H/HeJ. In NMRI and C3H/OuJ, strains which are responsive to bacterial lipopolysaccharides (LPS-responsive), regardless of the sex of the mouse, significant decrease in the amount of cyt P 450 was observed after LtriP treatment, with a concomitant reduction in ethoxyresorufin-O-deethylase (cyt P 450 1A-dependent) and 7-ethoxycoumarin-O-deethylase activities. This was not seen in C3H/HeJ (LPS-hyporesponsive) mice. These effects may be related to LtriP-dependent cytokine induction, since neither LtriP nor LPS stimulated interleukin-1 (IL-1) secretion by C3H/HeJ macrophages. 11- and 12-hydroxylations (11- and 12-OH) of lauric acid were compared in C3H/OuJ and C3H/HeJ mice. LtriP depressed the total enzymatic conversion of lauric acid in the two strains without modification of the 11/12-OH ratio for C3H/OuJ or male C3H/HeJ mice. However, in females C3H/HeJ mice this decrease was particularly significant and concerned especially the 12-OH activity (a marker of cyt P450 4A family). Although males of the three strains were more sensitive to irradiation than females, LtriP exerted a sex-independent radioprotection on NMRI and C3H/OuJ mice. Its radioprotective effect was illustrated by the preservation of all the enzymatic activities studied in treated NMRI mice, contrary to irradiated control animals. In contrast, for the C3H/HeJ strain, males were not protected by LtriP treatment and, furthermore, females showed a marked sensitization to irradiation.The effects in CH3/HeJ strain implicate LtriP in the control of cyt P 450 induction and of sensitivity to irradiation independently of IL-1 induction. 相似文献
16.
Toniolo C Crisma M Formaggio F Peggion C Epand RF Epand RM 《Cellular and molecular life sciences : CMLS》2001,58(9):1179-1188
Lipopeptaibols are members of a novel group of naturally occurring, short peptides with antimicrobial activity, characterized
by a lipophilic acyl chain at the N-terminus, a high content of the turn/helix forming α-aminoisobutyric acid and a 1,2-amino alcohol at the C-terminus. The amino acid sequences range from 6 to 10 residues and
the fatty acyl moieties from 8 to 15 carbon atoms. The peptide portion of lipopeptaibols can be shorter than those of the
nonlipidated peptaibols that range from 10 to 19 amino acid residues. The longest peptides fold into a mixed 310/α helix, whereas the shortest peptides tend to adopt a β-turn/sheet structure. Using solution methodologies, a series of analogues of trichogin GA IV was synthesized which allowed
determination of the minimal lipid chain and peptide main-chain lengths for the onset of membrane activity and exploitation
of a number of spectroscopic techniques aimed at determining its preferred conformation under a variety of conditions and
investigating in detail its mode of interaction with, and its effect on, the phospholipid membranes.
Received 26 January 2001; received after revision 7 March 2001; accepted 15 March 2001 相似文献
17.
The chirality of l-/dl-leucine (50–50%) cooligomerization was investigated in liquid and frozen aqueous solutions. Cooligomerization was carried
out by carbonyldiimidazole activation without initiator at an ambient (+22°C) and frozen (−18°C) temperature, respectively.
The separated samples obtained after different time intervals of treatment were completely hydrolyzed (HCl) and the diastereomeric
l- and d-leucine derivates of Marfey's reagent (1-fluoro-2,4-dinitrophenyl-5-l-alanine amide) were then traced and evaluated by RP-HPLC analysis. After 9 days of oligomerization, the l-Leu content was slightly enhanced in the liquid (57%) and somewhat more enhanced in the frozen (64%) samples. After 17 days,
however, the l-Leu content had decreased in the liquid (53%) and frozen (56%) conditions. These l-enantiomer amplifications indicate that an l-antipode is preferentially incorporated into the α-helical turn of the oligomer in the earlier stage of cooligomerization, while, later, the d-antipode is also incorporated. The role of ice in the improved stereoselection is discussed. This is the first recorded example
of the effect of freezing on stereoselection.
Received 27 October 2000; revised 11 December 2000; accepted 4 January 2000 相似文献
18.
Pepsinogens, progastricsins, and prochymosins: structure, function, evolution, and development 总被引:12,自引:0,他引:12
Kageyama T 《Cellular and molecular life sciences : CMLS》2002,59(2):288-306
Five types of zymogens of pepsins, gastric digestive proteinases, are known: pepsinogens A, B, and F, progastricsin, and
prochymosin. The amino acid and/or nucleotide sequences of more than 50 pepsinogens other than pepsinogen B have been determined
to date. Phylogenetic analyses based on these sequences indicate that progastricsin diverged first followed by prochymosin,
and that pepsinogens A and F are most closely related. Tertiary structures, clarified by X-ray crystallography, are commonly
bilobal with a large active-site cleft between the lobes. Two aspartates in the center of the cleft, Asp32 and Asp215, function
as catalytic residues, and thus pepsinogens are classified as aspartic proteinases. Conversion of pepsinogens to pepsins proceeds
autocatalytically at acidic pH by two different pathways, a one-step pathway to release the intact activation segment directly,
and a stepwise pathway through a pseudopepsin(s). The active-site cleft is large enough to accommodate at least seven residues
of a substrate, thus forming S4 through S3′ subsites. Hydrophobic and aromatic amino acids are preferred at the P1 and P1′ positions. Interactions at additional subsites are important in some cases, for example with cleavage of κ-casein by chymosin. Two potent naturally occurring inhibitors are known: pepstatin, a pentapeptide from Streptomyces, and a unique proteinous inhibitor from Ascaris. Pepsinogen genes comprise nine exons and may be multiple, especially for pepsinogen A. The latter and progastricsin predominate
in adult animals, while pepsinogen F and prochymosin are the main forms in the fetus/infant. The switching of gene expression
from fetal/infant to adult-type pepsinogens during postnatal development is noteworthy, being regulated by several factors,
including steroid hormones.
Received 25 May 2001; received after revision 27 August 2001; accepted 30 August 2001 相似文献
19.
Watanabe H Nakashima K Saito H Slaytor M 《Cellular and molecular life sciences : CMLS》2002,59(11):1983-1992
An endo-β-1,4-glucanase (EG) was purified from the hindgut of an Australian mound-building termite, Coptotermes lacteus. The hindgut extract had a peak separate from those for extracts obtained from the salivary glands and the midgut based on
sephacryl S-200 gel chromatography, and also demonstrated an origin different from the endogenous EGs of the termite itself.
The recovery was further purified by SDS-PAGE, and its N-terminal amino acid sequence analyzed. This showed high homology
to EGs from glycoside hydrolase family (GHF) 7. PCR-based cloning methods were applied to the hindgut contents of C. lacteus and individual protozoan symbionts from C. formosanus. cDNAs encoding putative EGs homologous to GHF7 members were then identified. The functionality of one of the putative proteins
was confirmed by its expression in Escherichia coli.
Received 18 September 2002; accepted 20 September 2002
RID="*"
ID="*"Corresponding author. 相似文献
20.
T. Yamada K. Kageyama Y. Joh J. Konishi K. Ienaga 《Cellular and molecular life sciences : CMLS》1998,54(2):125-128
2′-O-Methylinosine (1) has been isolated for the first time and shown to be an intrinsic hypotensive principle. Its probable in vivo precursor,
2′-O-methyladenosine (3), showed stronger and even orally potent hypotensive activity. Resistance of the methyladenosine (3) against adenosine deaminase is thought to contribute to its long-lasting activity. The effect of both nucleosides (1 and 3) was not accompanied with any significant change in heart rate, which is often observed with adenosine.
Received 2 October 1997; accepted 28 October 1997 相似文献