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1.
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
2.
Vera Gamulin Alexander Skorokhod Vadim Kavsan Isabel M. Müller Werner E. G. Müller 《Journal of molecular evolution》1997,44(3):242-252
We have analyzed the gene that encodes receptor tyrosine kinase (RTK) from the marine sponge Geodia cydonium, which belongs to the most ancient and simple metazoan groups, the Porifera. RTKs are enzymes found only in metazoa. The sponge
gene contains two introns in the extracellular part of the protein. However, the rest of the protein (transmembrane and intracellular
part), including the tyrosine kinase (TK)-domain, is encoded by a single exon. In contrast, all TK genes, so far known only
from higher animals (vertebrates), contain several introns especially in the TK-domain. The TK-domain of G. cydonium shows similarity with numerous members of receptor as well as nonreceptor TKs. Phylogenetic analysis of the sponge TK-domain
indicates that this enzyme branched off first from the common tree of metazoan TK proteins. Consequently, we assume that introns,
found in the TK-domains of genes from higher animals, were inserted into these genes after splitting off the sponge taxa from
other metazoan organisms (over 600 million years ago). Our results support the view that ancient genes were not ``in pieces.'
Received: 8 August 1996 / Accepted: 4 November 1996 相似文献
3.
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
4.
5.
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
6.
On the basis of 548 helminthological dissections the main foci of Anisakis infection of Caspian seal and the character of pathomorphological process in the stomach infected with the nematode Anisakis schupakovi have been established. 相似文献
7.
Stimulation of protein (collagen) synthesis in sponge cells by a cardiac myotrophin-related molecule from Suberites domuncula. 总被引:1,自引:0,他引:1
H C Schr?der A Krasko R Batel A Skorokhod S Pahler M Kruse I M Müller W E Müller 《FASEB journal》2000,14(13):2022-2031
The body wall of sponges (Porifera), the lowest metazoan phylum, is formed by two epithelial cell layers of exopinacocytes and endopinacocytes, both of which are associated with collagen fibrils. Here we show that a myotrophin-like polypeptide from the sponge Suberites domuncula causes the expression of collagen in cells from the same sponge in vitro. The cDNA of the sponge myotrophin was isolated; the potential open reading frame of 360 nt encodes a 120 aa long protein (Mr of 12,837). The sequence SUBDOMYOL shares high similarity with the known metazoan myotrophin sequences. The expression of SUBDOMYOL is low in single cells but high after formation of primmorph aggregates as well as in intact animals. Recombinant myotrophin was found to stimulate protein synthesis by fivefold, as analyzed by incorporation studies using [3H] lysine. In addition, it is shown that after incubation of single cells with myotrophin, the primmorphs show an unusual elongated, oval-shaped appearance. It is demonstrated that in the presence of recombinant myotrophin, the cells up-regulate the expression of the collagen gene. The cDNA for S. domuncula collagen was isolated; the deduced aa sequence shows that the collagenous internal domain is rather short, with only 24 G-x-y collagen triplets. We conclude that the sponge myotrophin causes in homologous cells the same/similar effect as the cardiac myotrophin in mammalian cells, where it is involved in initiation of cardial ventricular hypertrophy. We assume that an understanding of sponge molecular cell biology will also contribute to a further elucidation of human diseases, here of the cardiovascular system. 相似文献
8.
Seasonal changes in the coloration of the clypeus, mesonotum, and abdomen were studied in populations of the paper wasp, Polistes dominulus (Christ) in southern Ukraine. The color patterns in the populations were found to be different before and after hibernation. The frequencies of color morphs observed in the autumns of different years are similar, while the frequencies observed in spring vary from year to year. A tendency for pleometrosis is manifested by females of different color morphs in different years. The nest usurpers have darker patterns of the clypeus. A polyfunctional role of the coloration and pattern is supposed. 相似文献
9.
Alexander Skorokhod Peter Helmbold Benedikt Brors Peter Schirmacher Alexander Enk Roland Penzel 《PloS one》2013,8(3)
Malignant melanoma is a highly-aggressive type of malignancy with considerable metastatic potential and frequent resistance to cytotoxic agents. BRAF mutant protein was recently recognized as therapeutic target in metastatic melanoma. We present a newly-developed U-BRAFV600 approach – a universal pyrosequencing-based assay for mutation detection within activation segment in exon 15 of human braf. We identified 5 different BRAF mutations in a single assay analyzing 75 different formalin-fixed paraffin-embedded (FFPE) samples of cutaneous melanoma metastases from 29 patients. We found BRAF mutations in 21 of 29 metastases. All mutant variants were quantitatively detectable by the newly-developed U-BRAFV600 assay. These results were confirmed by ultra-deep-sequencing validation (∼60,000-fold coverage). In contrast to all other BRAF state detection methods, the U-BRAFV600 assay is capable of automated quantitative identification of at least 36 previously-published BRAF mutations. Under the precaution of a minimum of 3% mutated cells in front of a background of wild type cells, U-BRAFV600 assay design completely excludes false wild-type results. The corresponding algorithm for classification of BRAF-mutated variants is provided. The single-reaction assay and data analysis automation makes our approach suitable for the assessment of large clinical sample sizes. Therefore, we suggest U-BRAFV600 assay as a most powerful sequencing-based diagnostic tool to automatically identify BRAF state as a prerequisite to targeted therapy. 相似文献
10.
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