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1.
Patterns of Root Colonization in Epacridaceous Plants Collected from Different Sites 总被引:2,自引:0,他引:2
Root colonization was studied in ten species of the Epacridaceaeat three sites in Victoria by morphological and cross-inoculationexperiments. The sites and genera chosen were Cranbourne [Epacrisimpressa Labill. andLeucopogon ericoides(Smith) R. Br.] andRye [L. parviflorus(Andrews) Lindley] on the Mornington Peninsula,and the Grampians[Astroloma conostephioides(Sond.) Benth.,A.humifusum(Cav.) R. Br.,A pinifolium(R. Br.) Benth,Brachylomadaphnoides(Smith) Benth.,E. impressa, E. impressavar.grandifloraBenth.andStyphelia adscendensR. Br.] in western Victoria. For morphologicalstudies, samples of roots from each species at each site werecleared and stained and examined microscopically. For cross-inoculationstudies, cuttings from each site were struck in potting mediuminoculated with soil from the same and other sites. The ericoidmycorrhizae in the roots of plants found at or grown in Cranbourneand Rye soils were similar. Both were significantly differentfrom the internal hyphae found in the roots of plants foundat or grown in Grampians soils, which were three times largerin diameter and formed dense coils which filled the host celland invaded adjacent epidermal cells. This suggests that morethan one fungus is involved in the relationships, that the MorningtonPeninsula sites had a different fungus from the Grampians siteand that host specificity is low. Vesicular structures werealso found commonly on plants at the Grampians site, in contrastwith other sites. Epacridaceae; root; fungus; mycorrhiza; morphology; inoculation 相似文献
2.
Interspecific hybridization of cultivated rice, Oryza sativa L. with the wild rice, O. minuta Presl.
A. L. Mariam A. H. Zakri M. C. Mahani M. N. Normah 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(5-6):664-671
Crosses were made between four varieties (Mahsuri, Setanjung, MR84 and MR103) of Oryza sativa L. (2n=24, AA) and one accession of O. minuta (2n= 8, BBCC). The seed set obtained ranged between 9.5% and 25.1% depending on the rice variety used. By rescuing 14-day-old embryos and culturing them on 25%-strength MS medium we obtained a total of 414 F1 hybrids. The F1s were vigorous, tillered profusely, were perennial and male-sterile. The hybrids were triploid (ABC) with 36 chromosomes and showed irregular meiosis. The average frequency and range of chromosome associations at metaphase I or early anaphase I pollen mother cells of F1 plants were 29.31(16–36) Is +3.32(0–10) IIs+0.016(0–1) IIIs+0.002(0–1) IVs. Upon backcrossing the original triploid hybrids and colchicine-treated hybrids to their respective recurrent parents, and further embryo rescue, 17 backcross-1 (BC1) plants were obtained. Of all the crosses using MR84, no BC1 plant was obtained even after pollinating 13 894 spikelets of the triploid hybrid. The BC1s were similar in appearence to the F1s and were male-sterile, their chromosome number ranged from 44 to 48. By backcrossing these BC1s and nurturing them through embryo rescue, we obtained 32 BC2 plants. Of these, however, only 18 plants grew vigorously. One of these plants has 24 chromosomes and the other 17 have chromosome numbers ranging between 30 and 37. The 24-chromosome plant was morphologically similar to the O. sativa parent and was partially fertile with a pollen and spikelet fertility of 58.8% and 12.5% respectively. All of the F1 and BC1 plants were found to be resistant to five Malaysian isolates (XO66, XO99, XO100, XO257 and XO319) of Xanthomonas campestris pv oryzae. Amongst the BC2s, the reaction varied from resistant to moderately susceptible. The 24-chromosome BC2 plant was resistant to the four isolates and moderately resistant to isolate XO100 to which the O. sativa parent was susceptible.Part of PhD thesis submitted by first author to Universiti Kebangsaan Malaysia, Bangi 相似文献
3.
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
4.
Md-Zain BM Mohamad M Ernie-Muneerah MA Ampeng A Jasmi A Lakim M Mahani MC 《Genetics and molecular research : GMR》2010,9(4):1987-1996
Mitochondrial DNA cytochrome c oxidase II (COII) gene sequences of Malaysian Cercopithecidae were examined to ascertain their phylogenetic relationships. Colobinae were represented by the genera Presbytis, Trachypithecus and Nasalis, while the genus Macaca represented Cercopithecinae. DNA amplification and sequencing of the COII gene was performed on 16 samples. Symphalangus syndactylus (Hylobatidae) was used as the outgroup. Data were analyzed using both character (maximum parsimony) and distance (neighbor-joining) methods. Tree topologies indicated that Colobinae and Cercopithecinae have their own distinct monophyletic clade. This result was well supported by bootstrap values and genetic distances derived from the Kimura-2-parameter algorithm. Separation of Macaca nemestrina from M. fascicularis was also well supported by bootstrap values. In addition, tree topologies indicate a good resolution of the Colobinae phylogenetic relationships at the intergeneric level, but with low bootstrap support. The position of Nasalis remained problematic in both trees. Overall, COII is a good gene candidate for portraying the phylogenetic relationships of Malaysian primates at the inter- and intra-subfamily levels. 相似文献
5.
Andréia S Lessa Bruno D Paredes Juliana V Dias Adriana B Carvalho Luiz Fernando Quintanilha Christina M Takiya Bernardo R Tura Guilherme FM Rezende Antonio C Campos de Carvalho Célia MC Resende Regina CS Goldenberg 《BMC veterinary research》2010,6(1):1-10
Background
Atypical scrapie was first identified in Norwegian sheep in 1998 and has subsequently been identified in many countries. Retrospective studies have identified cases predating the initial identification of this form of scrapie, and epidemiological studies have indicated that it does not conform to the behaviour of an infectious disease, giving rise to the hypothesis that it represents spontaneous disease. However, atypical scrapie isolates have been shown to be infectious experimentally, through intracerebral inoculation in transgenic mice and sheep. The first successful challenge of a sheep with 'field' atypical scrapie from an homologous donor sheep was reported in 2007.Results
This study demonstrates that atypical scrapie has distinct clinical, pathological and biochemical characteristics which are maintained on transmission and sub-passage, and which are distinct from other strains of transmissible spongiform encephalopathies in the same host genotype.Conclusions
Atypical scrapie is consistently transmissible within AHQ homozygous sheep, and the disease phenotype is preserved on sub-passage. 相似文献6.
van Beers JJ Raijmakers R Alexander LE Stammen-Vogelzangs J Lokate AM Heck AJ Schasfoort RB Pruijn GJ 《Arthritis research & therapy》2010,12(6):R219
Introduction
Rheumatoid arthritis (RA) frequently involves the loss of tolerance to citrullinated antigens, which may play a role in pathogenicity. Citrullinated fibrinogen is commonly found in inflamed synovial tissue and is a frequent target of autoantibodies in RA patients. To obtain insight into the B-cell response to citrullinated fibrinogen in RA, its autoepitopes were systematically mapped using a new methodology. 相似文献7.
8.
Sidders B Withers M Kendall SL Bacon J Waddell SJ Hinds J Golby P Movahedzadeh F Cox RA Frita R Ten Bokum AM Wernisch L Stoker NG 《Genome biology》2007,8(12):R265-13
We describe an analysis, applicable to any spotted microarray dataset produced using genomic DNA as a reference, that quantifies prokaryotic levels of mRNA on a genome-wide scale. Applying this to Mycobacterium tuberculosis, we validate the technique, show a correlation between level of expression and biological importance, define the complement of invariant genes and analyze absolute levels of expression by functional class to develop ways of understanding an organism's biology without comparison to another growth condition. 相似文献
9.
José MC Ribeiro Bruno Arcà Fabrizio Lombardo Eric Calvo My Van Phan Prafulla K Chandra Stephen K Wikel 《BMC genomics》2007,8(1):1-27
Background
The number of completely sequenced plastid genomes available is growing rapidly. This array of sequences presents new opportunities to perform comParative analyses. In comParative studies, it is often useful to compare across wide phylogenetic spans and, within angiosperms, to include representatives from basally diverging lineages such as the genomes reported here: Nuphar advena (from a basal-most lineage) and Ranunculus macranthus (a basal eudicot). We report these two new plastid genome sequences and make comparisons (within angiosperms, seed plants, or all photosynthetic lineages) to evaluate features such as the status of ycf15 and ycf68 as protein coding genes, the distribution of simple sequence repeats (SSRs) and longer dispersed repeats (SDR), and patterns of nucleotide composition.Results
The Nuphar [GenBank:NC_008788] and Ranunculus [GenBank:NC_008796] plastid genomes share characteristics of gene content and organization with many other chloroplast genomes. Like other plastid genomes, these genomes are A+T-rich, except for rRNA and tRNA genes. Detailed comparisons of Nuphar with Nymphaea, another Nymphaeaceae, show that more than two-thirds of these genomes exhibit at least 95% sequence identity and that most SSRs are shared. In broader comparisons, SSRs vary among genomes in s of abundance and length and most contain repeat motifs based on A and T nucleotides.Conclusion
SSR and SDR abundance varies by genome and, for SSRs, is proportional to genome size. Long SDRs are rare in the genomes assessed. SSRs occur less frequently than predicted and, although the majority of the repeat motifs do include A and T nucleotides, the A+T bias in SSRs is less than that predicted from the underlying genomic nucleotide composition. In codon usage third positions show an A+T bias, however variation in codon usage does not correlate with differences in A+T-richness. Thus, although plastome nucleotide composition shows "A+T richness", an A+T bias is not apparent upon more in-depth analysis, at least in these aspects. The pattern of evolution in the sequences identified as ycf15 and ycf68 is not consistent with them being protein-coding genes. In fact, these regions show no evidence of sequence conservation beyond what is normal for non-coding regions of the IR. 相似文献10.
Ang KC Leow JW Yeap WK Hood S Mahani MC Md-Zain BM 《Genetics and molecular research : GMR》2011,10(2):640-649
Malaysia remains as a crossroad of different cultures and peoples, and it has long been recognized that studying its population history can provide crucial insight into the prehistory of Southeast Asia as a whole. The earliest inhabitants were the Orang Asli in Peninsular Malaysia and the indigenous groups in Sabah and Sarawak. Although they were the earliest migrants in this region, these tribes are divided geographically by the South China Sea. We analyzed DNA sequences of 18 Orang Asli using mitochondrial DNA extracted from blood samples, each representing one sub-tribe, and from five Sarawakian Iban. Mitochondrial DNA was extracted from hair samples in order to examine relationships with the main ethnic groups in Malaysia. The D-loop region and cytochrome b genes were used as the candidate loci. Phylogenetic relationships were investigated using maximum parsimony and neighbor joining algorithms, and each tree was subjected to bootstrap analysis with 1000 replicates. Analyses of the HVS I region showed that the Iban are not a distinct group from the Orang Asli; they form a sub-clade within the Orang Asli. Based on the cytochrome b gene, the Iban clustered with the Orang Asli in the same clade. We found evidence for considerable gene flow between Orang Asli and Iban. We concluded that the Orang Asli, Iban and the main ethnic groups of Malaysia are probably derived from a common ancestor. This is in agreement with a single-route migration theory, but it does not dismiss a two-route migration theory. 相似文献