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Mitochondrial DNA evolution in the genus Equus 总被引:7,自引:0,他引:7
Employing mitochondrial DNA (mtDNA) restriction-endonuclease maps as the
basis of comparison, we have investigated the evolutionary affinities of
the seven species generally recognized as the genus Equus. Individual
species' cleavage maps contained an average of 60 cleavage sites for 16
enzymes, of which 29 were invariant for all species. Based on an average
divergence rate of 2%/Myr, the variation between species supports a
divergence of extant lineages from a common ancestor approximately 3.9 Myr
before the present. Comparisons of cleavage maps between Equus przewalskii
(Mongolian wild horse) and E. caballus (domestic horse) yielded estimates
of nucleotide sequence divergence ranging from 0.27% to 0.41%. This range
was due to intraspecific variation, which was noted only for E. caballus.
For pairwise comparisons within this family, estimates of sequence
divergence ranged from 0% (E. hemionus onager vs. E. h. kulan) to 7.8% (E.
przewalskii vs. E. h. onager). Trees constructed according to the parsimony
principle, on the basis of 31 phylogenetically informative restriction
sites, indicate that the three extant zebra species represent a
monophyletic group with E. grevyi and E. burchelli antiquorum diverging
most recently. The phylogenetic relationships of E. africanus and E.
hemionus remain enigmatic on the basis of the mtDNA analysis, although a
recent divergence is unsupported.
相似文献
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The consequence of harvesting young leaves of cassava as vegetable on the vulnerability of the crop to cassava mosaic disease (CMD) and on storage root yield was investigated using 30 cassava genotypes planted in IITA fields located in the humid forest (Port Harcourt?:?Onne), forest-savannah transition (Ibadan), southern guinea savannah (Mokwa) and northern guinea savannah (Zaria) agroecologies in Nigeria. Tender apical leaves and shoots of the cassava genotypes were removed from forty plants per cassava genotype with the same number of plants considered as control. Whitefly infestation, disease incidence (DI) and symptom severity (ISS) of the disease were assessed at monthly interval for six months and also at the ninth month after planting (MAP). Yield reduction due to this treatment was calculated as percentage harvest index (HI). Whitefly population fluctuated throughout the period of observation at all locations with higher population obtained generally for treated plants compared to control plants. Sprouting leaves of some treated genotypes were observed with severe mosaic symptoms, while corresponding control showed no mosaic symptoms. Contrarily, no remarkable difference was observed in Zaria between the mean ISS of treated and control cassava genotypes. There was a highly significant difference (P?<?0.01) in DI and ISS among cassava genotypes across all locations. Also, there was a highly significant interaction (P?<?0.01) in symptom severity between location (loc) and genotype, genotype and treatment (trt), loc and trt. Interaction between loc, genotypes and trt with regard to DI was highly significant at 2, 3 and 4 MAP, while with ISS, the interaction was highly significant all through the counting period. There was a positive relationship between DI and ISS on plants of genotypes 96/1039 and ISU. The percentage HI (27.4) of treated plants of genotype 95/0166 in Ibadan was remarkably lower than the value obtained for corresponding control (41.9) plants. Also, sharp distinction in% HI of treated (39.5) and control (43.8) ISU was observed in Onne with their respective ISS values as 3.7 and 3.2. Therefore, harvesting tender apical leaves and shoots of cassava as vegetables should be discouraged as it increases the severity of CMD infection in the regenerating shoots of cassava with attendant storage root yield reduction. 相似文献
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Moreno-Valenzuela OA Minero-García Y Brito-Argáez L Carbajal-Mora E Echeverría O Vázquez-Nin G Loyola-Vargas VM 《Molecular biotechnology》2003,23(1):11-18
We investigated the intracellular distribution of tryptophan decarboxylase (TDC) (EC 4.1.1.28) in Catharanthus roseus hairy roots using immunofluorescence and immunogold techniques. TDC was detected by immunofluorescence localization in the
cytosol and in the apoplastic region of the meristematic cells of the roots, with a slight enrichment in the epidermal cells
of the root cap and in the meristematic region. In the enlargement zone, TDC was localized only in the first three layers
of the cortex. In the maturation zone, the enzyme was not present. Immunogold studies confirmed that the enzyme was localized
in the cytosol of the meristematic region, and intense gold labeling was found in the apoplastic zone. A protein fraction
isolated from the apoplastic zone and assayed for TDC activity showed high activity. 相似文献
5.
Echevarría-Machado I Sánchez-Cach LA Hernández-Zepeda C Rivera-Madrid R Moreno-Valenzuela OA 《Molecular biotechnology》2005,31(2):129-135
A protocol is described for rapid DNA isolation from Malvaceae plant species and different tissues of Bixaceae that contain
large amounts of polysaccharides, polyphenols, and pigments that interfere with DNA extractions. The method is a modification
of Dellaporta et al. The current protocol is simple, and no phenolchloroform extraction, ethanol, or isopropranol precipitation
is required. The method is based in the incubation of soluble DNA with silica, mix in batch during the extraction. The procedure
can be completed in 2 h and many samples can be processed at the same time. DNA of excellent quality was recovered and used
for polymerase chain reaction (PCR) amplification, restriction enzyme digestion, and Southern blot analysis. The method was
used with healthy Bixa orellana and virus-infected Malvaceae plants. 相似文献
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TO Sogbanmu AO Osibona OA Oguntunde AA Otitoloju 《African Journal of Aquatic Science》2018,43(3):281-292
Physiological, biochemical and histological indices in Clarias gariepinus broodstock, and teratogenic indices in embryos exposed to sublethal concentrations of naphthalene, phenanthrene and pyrene were investigated in 2014 using a static-renewal bioassay protocol. Phenanthrene (1.41 mg l?1) was the most toxic, followed by pyrene (1.53 mg l?1) and naphthalene (7.21 mg l?1), based on 96 h LC50 values. Hepatosomatic indices were significantly higher in naphthalene- and pyrene-treated males compared with solvent controls, whereas fecundity in females was significantly lower by factors of 2.4 (naphthalene), 2.8 (phenanthrene) and 2.4 (pyrene), compared with controls. Catalase levels were lower in female phenanthrene-treated fish compared with controls. Histological alterations observed in PAH-treated fish include oedema, inflammatory cells, epithelial lifting and hyperplasia in the gills, vacuolation, haemosiderin pigments and sinusoidal congestion in the liver, and degenerated zona radiata in the ovary. Teratogenic effects were not observed, as evidenced by the lack of histological alterations in embryos spawned from pre-exposed broodstock. Sex-specific responses and the utility of biomarkers at cellular and individual levels of organisation are therefore demonstrated for holistic evaluations of polycyclic aromatic hydrocarbons in ecotoxicological studies. 相似文献
8.
Effect of differentiation on the regulation of indole alkaloid production in Catharanthus roseus hairy roots 总被引:4,自引:0,他引:4
O. A. Moreno-Valenzuela R. M. Galaz-Avalos Y. Minero-García V. M. Loyola-Vargas 《Plant cell reports》1998,18(1-2):99-104
In vitro cultures of hairy root derived from Catharanthus roseus accumulate higher levels of indole alkaloids than cell suspension cultures. Hairy roots were interconverted to undifferentiated
cells by manipulation of the culture medium. When the concentration of micronutrients in the culture medium was five times
that of Phillips and Collins (1979) medium, cell suspensions formed from the hairy roots. The alkaloid content was five times
lower in the cell suspensions than in the control, but upon regeneration of the roots the alkaloid content regained its original
level. The formation of cell suspensions from hairy roots was also accompanied by a reduction in tryptophan decarboxylase
and the strictosidine synthase activity to less than 5% and 30%, respectively. 3-Hydroxymethylglutaryl coenzyme A reductase
activity was the same in the cell suspension and in the regenerated line.
Received: 12 February 1998 / Revision received: 21 May 1998 / Accepted: 5 June 1998 相似文献
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Robles-Hernández L J Hernández-Huerta AC González-Franco OA Hernández-Rodríguez A Núñez-Barrios R Pérez-Leal 《Phyton》2015,84(2):253-261
Chili pepper is one of the main crops of economic importance in Mexico, and Fusarium wilting is a disease that limits its production. In addition, the inappropriate use of agrochemicals in farming activities generate environmental and health problems. Therefore, in this study the effectiveness of Streptomyces sp PRIO41 was evaluated as a (1) biocontrol agent of Fusarium spp and (2) plant growth promoter bacteria. Assays of pathogenicity and virulence of Fusarium spp. in jalapeño pepper seeds, and interactions of these pathogens with Streptomyces PRIO41 were evaluated under two nutritional conditions. In the greenhouse, the effectiveness of Streptomyces sp. PRIO41 was determined as a (1) biocontrol of Fusarium, and (2) plant growth promoter of wilt of pepper plants. The results showed that all fungal isolates caused symptoms in pepper seeds and seedlings with different degrees of virulence. Interactions in vitro showed that Streptomyces showed the most effective range of virulence against Fusarium isolates in the poor medium (37.6%-100%), with fungicidal effects in some cases. In the greenhouse, Streptomyces PRIO41 reduced Fusarium wilting up to a 40%, and positively affected all vegetative growth parameters, particularly plant height, leaf area, root length, and leaf and root dry biomasses. This study showed the potential of Streptomyces PRIO41 as a biocontrol agent of Fusarium spp., and as a biofertilizer of pepper plants. 相似文献