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121.
Genetic variation of Trigonobalanus verticillata,a primitive species of Fagaceae,in Malaysia revealed by chloroplast sequences and AFLP markers 总被引:1,自引:0,他引:1
The genetic variation of Trigonobalanus verticillata, the most recently described genus of Fagaceae, was studied using chloroplast DNA sequences and AFLP fingerprinting. This species has a restricted distribution that is known to include seven localities in tropical lower montane forests in Malaysia and Indonesia. A total of 75 individuals were collected from Bario, Kinabalu, and Fraser's Hill in Malaysia. The sequences of rbcL, matK, and three non-coding regions (atpB-rbcL spacer, trnL intron, and trnL-trnF spacer) were determined for 19 individuals from these populations. We found a total of 30 nucleotide substitutions and four length variations, which allowed identification of three haplotypes characterizing each population. No substitutions were detected within populations, while the tandem repeats in the trnL -trnF spacer had a variable repeat number of a 20-bp motif only in Kinabalu. The differentiation of the populations inferred from the cpDNA molecular clock calibrated with paleontological data was estimated to be 8.3 MYA between Bario and Kinabalu, and 16.7 MYA between Fraser's Hill and the other populations. In AFLP analysis, four selective primer pairs yielded a total of 431 loci, of which 340 (78.9%) were polymorphic. The results showed relatively high gene diversity (H(S) = 0.153 and H(T) = 0.198) and nucleotide diversity (pi(S) = 0.0132 and pi(T) = 0.0168) both within and among the populations. Although the cpDNA data suggest that little or no gene flow occurred between the populations via seeds, the fixation index estimated from AFLP data (F(ST) = 0.153 and N(ST) = 0.214) implies that some gene flow occurs between populations, possibly through pollen transfer. 相似文献
122.
A pig kidney cDNA library was screened for the porcine ortholog of the multispecific organic anion transporter 1 (pOAT1). Several positive clones were isolated resulting in two alternatively spliced cDNA clones of pOAT1 (pOAT1 and pOAT1A). pOAT1-cDNAs consist of 2126 or 1895 base pairs (EMBL Acc. No. AJ308234 and AJ308235) encoding 547 or 533 amino acid residue proteins with 89, 87, 83 and 81% homology to the human, rabbit, rat, and mouse OAT1, respectively. Heterologous expression of pOAT1 in Xenopus laevis oocytes revealed an apparent K(m) for [3H]PAH of 3.75 +/- 1.6 microM. [3H]PAH uptake mediated by pOAT1 was abolished by 0.5 mM glutarate or 1 mM probenecid. Functional characterization of pOAT1A did not show any affinity for [3H]PAH. In summary, we cloned two alternative splice variants of the pig ortholog of organic anion transporter 1. One splice form (pOAT1) showed typical functional characteristics of organic anion transporter 1, whereas the second form appears not to transport PAH. 相似文献
123.
Navarro CE Saeed SA Murdock C Martinez-Fuentes AJ Arora KK Krsmanovic LZ Catt KJ 《Molecular endocrinology (Baltimore, Md.)》2003,17(12):1792-1804
Immortalized GnRH neurons (GT1-7) express receptors for estrogen [estrogen receptor-alpha and-13(ERa and ERI3)] and progesterone (progesterone receptor A) and exhibit positive immunostaining for both intracellular and plasma membrane ERs. Exposure of GT1-7 cells to picomolar estradiol concentrations for 5-60 min caused rapid, sustained,and dose-dependent inhibition of cAMP production. In contrast, treatment with nanomolar estradiol concentrations for 60 min increased cAMP production. The inhibitory and stimulatory actions of estradiol on cAMP formation were abolished by the ER antagonist, ICI 182,780. The estradiol-induced inhibition of cAMP production was prevented by treatment with pertussis toxin, consistent with coupling of the plasma membrane ER to an inhibitory G protein. Coimmunoprecipitation studies demonstrated an estradiol-regulated stimulatory interaction between ERa and G,3 that was prevented by the ER antagonist, ICI 182,780. Exposure of perifused GT1-7 cells and hypothalamic neurons to picomolar estradiol levels increased the GnRH peak interval, shortened peak duration, and increased peak amplitude. These findings indicate that occupancy of the plasma membrane-associated ERs expressed in GT1-7 neurons by physio-logical estradiol levels causes activation of a G, protein and modulates cAMP signaling and neuropeptide secretion. 相似文献
124.
Rahmani M Susidarti RA Ismail HB Sukari MA Hin TY Lian GE Ali AM Kulip J Waterman PG 《Phytochemistry》2003,64(4):873-877
In a continuation of our study of the Rutaceae, detailed chemical investigation on Micromelum minutum (Rutaceae) collected from Sepilok, Sabah, Malaysia gave four new coumarins. The structures of the coumarins have been fully characterised by spectroscopic methods as 3",4"-dihydrocapnolactone 1, 2',3'-epoxyisocapnolactone 2, 8-hydroxyisocapnolactone-2',3'-diol 3 and 8-hydroxy-3",4"-dihydrocapnolactone-2',3'-diol 4. 相似文献
125.
The ultrasonic velocity, density and viscosity of two egg proteins, ovalbumin and ovotransferrin in phosphate buffer have been studied at the physiological pH values. The thermodynamic functions for unfolding, ellipticity, surface amino acid residues and compressibility have been obtained for thermal and chemical denaturation in these food proteins. The computed values of Huggin's constant and shape factor, at a fixed ionic strength 0.16 M are found to be in agreement with the reported values for globular proteins. The slow increase in free-energy of unfolding with temperature at a fixed pH 7 suggests uncoiling and in turn, disappearance of biological activity. It has been observed that the effects of temperature and chemical denaturant on the native protein may give rise to different conformational states. In the presence of urea and sodium dodecyl sulphate (SDS), the proteins gave the excessively denatured states at 25 degrees C and pH 7, in comparison to the thermal denatured state. The positive values of partial adiabatic compressibility (see symbol in text) beta s over the temperature range 45-75 degrees C suggest the possibility of large internal flexibility in ovotransferrin than in ovalbumin. 相似文献
126.
Expression of transmembrane carbonic anhydrase isoenzymes IX and XII in normal human pancreas and pancreatic tumours 总被引:1,自引:1,他引:0
Kivelä AJ Parkkila S Saarnio J Karttunen TJ Kivelä J Parkkila AK Pastoreková S Pastorek J Waheed A Sly WS Rajaniemi H 《Histochemistry and cell biology》2000,114(3):197-204
Carbonic anhydrase (CA) IX and XII are transmembrane isoenzymes which are expressed in several epithelia and overexpressed in some carcinomas. They have recently been linked to von Hippel-Lindau gene-mediated carcinogenesis in that both isoenzymes are downregulated by the product of the wild-type von Hippel-Lindau tumour suppressor gene. This paper describes the localisation of CA IX and XII in the normal human pancreas and pancreatic tumours. Both isoenzymes showed positive reaction in the basolateral plasma membrane of the normal acinar and ductal epithelia. The hyperplastic ductal epithelium in tumour specimens generally showed an increased staining for CA IX. Of 29 malignant tumours of exocrine pancreas, 10 showed moderate or strong immunoreaction for CA IX. The signal for CA XII remained weak in most malignant lesions. The present results show that both CA IX and XII are unevenly expressed in the ductal and acinar compartments of the human pancreas. The expression of these isoenzymes in a relatively low number of malignant tumour specimens suggests that they have a limited value in diagnostic evaluation of pancreatic carcinoma. However, the increased expression of CA IX in hyperplastic ductal epithelium may contribute to the pancreatic tumourigenesis. 相似文献
127.
Son Radu Shahilah Abdul Mutalib Gulam Rusul Zainori Ahmad Tadaaki Morigaki Norio Asai Yung Bu Kim Jun Okuda Mitsuaki Nishibuchi 《Applied microbiology》1998,64(3):1153-1156
Twelve strains of Escherichia coli O157:H7 were isolated from 9 of 25 beef samples purchased from retail stores in Malaysia. These strains produced Shiga toxin 2 with or without Shiga toxin 1 and had the eae gene and a 60-MDa plasmid. The antibiograms and the profiles of the arbitrarily primed PCR of the strains were diverse, suggesting that the strains may have originated from diverse sources. 相似文献
128.
The Fur-Regulated Gene Encoding the Alternative Sigma Factor PvdS Is Required for Iron-Dependent Expression of the LysR-Type Regulator PtxR in Pseudomonas aeruginosa 总被引:3,自引:0,他引:3
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Michael L. Vasil Urs A. Ochsner Zaiga Johnson Jane A. Colmer Abdul N. Hamood 《Journal of bacteriology》1998,180(24):6784-6788
129.
Abdul Gafur Chihiro Tanaka Kiminori Shimizu Seiji Ouchi Mitsuya Tsuda 《Mycoscience》1998,39(2):155-159
Nine polyoxin-resistant mutants ofCochliobolus heterostrophus were isolated after ethyl methanesulphonate mutagenesis. All were highly resistant to polyoxin (MIC≥1,600 ppm). Crosses between
the mutants and a wild-type strain revealed that the resistance trait was inherited to the offsprings in different fashions.
Four of the mutant strains inherited polyoxin resistance in a 1∶1 segregation ratio, indicating that the phenotypes in these
strains were due to alteration at a single locus. Allelism tests revealed four new loci,Pol1, Pol2, Pol3 andPol4, for polyoxin resistance in these mutant strains. The genes responsible for the phenotypes of the other five mutant strains
were not determined, because of extremely slow growth of progenies in one cross, sterility in another cross, and inexplicable
responses to polyoxin of the progenies in the other crosses. No linkage was detected between the genes for polyoxin resistance
and mating type. 相似文献
130.
Abdelrahim Abubakr Abdul Razak Alimon Halimatun Yaakub Norhani Abdullah Michael Ivan 《PloS one》2015,10(3)
The present study aims to evaluate the effects of feeding palm oil by-products based diets on different muscle fatty acid profiles in goats. Thirty-two Cacang × Boer goats were randomly assigned to four dietary treatments: (1) control diet (CD), (2) 80% decanter cake diet (DCD), (3) 80% palm kernel cake diet (PKCD) and (4) CD plus 5% palm oil (PO) supplemented diet (CPOD). After 100 days of feeding, four goats from each group were slaughtered and longissimus dorsi (LD), infraspinatus (IS) and biceps femoris (BF) were sampled for analysis of fatty acids. Goats fed the PKCD had higher (P<0.05) concentration of lauric acid (C12:0) than those fed the other diets in all the muscles tested. Compared to the other diets, the concentrations of palmitic acid (C16:0) and stearic acid (C18:0) were lower (P<0.05) and that of linoleic acid (C18:2 n-6) was higher (P<0.05) in the muscles from goats fed the CD. It was concluded that palm kernel cake and decanter cake can be included in the diet of goats up to 80% with more beneficial than detrimental effects on the fatty acid profile of their meat. 相似文献