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The molecular evolution of mammalian Y-linked DNA sequences is of special
interest because of their unique mode of inheritance: most Y- linked
sequences are clonally inherited from father to son. Here we investigate
the use of Y-linked sequences for phylogenetic inference. We describe a
comparative analysis of a 515-bp region from the male sex- determining
locus, Sry, in 22 murine rodents (subfamily Murinae, family Muridae),
including representatives from nine species of Mus, and from two additional
murine genera--Mastomys and Hylomyscus. Percent sequence divergence was
< 0.01% for comparisons between populations within a species and was
0.19%-8.16% for comparisons between species. Our phylogenetic analysis of
12 murine taxa resulted in a single most- parsimonius tree that is highly
concordant with phylogenies based on mitochondrial DNA and allozymes. A
total evidence tree based on the combined data from Sry, mitochondrial DNA,
and allozymes supports (1) the monophyly of the subgenus Mus, (2) its
division into a Palearctic group (M. musculus, M. domesticus, M.
spicilegus, M. Macedonicus, and M. spretus) and an Oriental group (M.
cookii++, M. cervicolor, and M. caroli), and (3) sister-group relationships
between M. spicilegus and M. macedonicus and between M. cookii and M.
cervicolor. We argue that Y- chromosome DNA sequences represent a valuable
new source of characters for phylogenetic inference.
相似文献
4.
Ronald H. Reeder Donald D. Brown Peter K. Wellauer Igor B. Dawid 《Journal of molecular biology》1976,105(4):507-516
The non-transcribed spacer regions in Xenopus laevis ribosomal DNA vary in length, even within a single nucleolar organizer. The pattern of spacer lengths is sufficiently different from one nucleolar organizer to another to allow the pattern to be used as a genetic marker. We have analyzed the spacer patterns of rDNA2 from a total of 50 progeny from three separate matings. Spacer patterns were inherited with no detectable change in all but two cases. The reproducibility of the patterns among siblings and their stable inheritance between generations rule out sudden mechanisms for gene evolution, such as the master-slave model, and support more gradual mechanisms.Two animals out of 50 showed marked changes in their rDNA spacer patterns. It is not possible at present to decide which of several possible mechanisms were responsible for the observed changes. 相似文献
5.
PK Hepler 《The Journal of cell biology》1980,86(2):490-499
Membranes in the mitotic apparatus have been investigated ultrastructually in dividing cells of barley (Hordeum vulgare). After osmium tetroxide- potassium ferricyanide or ferrocyanide postfixation (OsFeCN) of material that had been fixed in glutaraldehyde in the presence of Ca(++), the nuclear envolope (NE)-endoplasmic reticulum (ER) complex is selectively stained, permitting observations on the cellular pattern and structural ramifications of this membrane system that have not been previously recognized. Specifically, it is observed that membrane system that have not been previously recognized. Specifically, it is observed that during mitosis the NE-ER forms a continuous membrane system that ensheathes and isolates the mitotic apparatus (MA). Elements of ER progressively accumulate in the region of the spindle pole, becoming most concentrated by early anaphase. Within the MA itself, there are striking spindle- membrane associations; in particular, tubular elements of predominantly smooth NE-ER invade the spindle interior selectively along kinetochore microtubules. The membrane elements at the pole and surrounding the MA consist of tubular reticulum and fenestrated lamellae. Membranes of the MA thus resemble in considerable detail the tubular network and fenestrated elements of the sarcoplasmic reticulum of muscle. It is suggested that the NE-ER of the dividing barley cell may function in one or both of the following ways: (a) to control the concentration of free Ca(++) in the MA and (b) to serve as an anchor to chromosome motion. 相似文献
6.
Nine white-rot fungal strains were screened for biodecolourization of brilliant green, cresol red, crystal violet, congo red
and orange II. Dichomitus squalens, Phlebia fascicularia and P. floridensis decolourized all of the dyes on solid agar medium and possessed better decolourization ability than Phanerochaete chrysosporium when tested in nitrogen-limited broth medium. Journal of Industrial Microbiology & Biotechnology (2002) 28, 201–203 DOI: 10.1038/sj/jim/7000222
Received 12 July 2001/ Accepted in revised form 22 October 2001 相似文献
7.
MNK Clottey R Asmah PK Ofori-Danson MY Ameworwor AY Karikari 《African Journal of Aquatic Science》2016,41(4):473-480
The effects of cage fish farming on physico-chemical and bacteriological water quality in Lake Volta, Ghana, were investigated in 2013–2014. Farmed and unfarmed (control) areas of the lake were selected for monitoring. Nutrients, temperature, dissolved oxygen, conductivity, turbidity, pH, total coliforms, Pseudomonas and Vibrio spp. in the water were monitored monthly. Analyses of the water samples were carried out according to standard procedures. Physico-chemical quality of the water in both farm and control sites were within ranges typical of minimally impacted water and did not vary significantly between the two contrasting sites. The bacteriological analysis, however, revealed contamination of the lake water by fish farming. The bacterial counts at the farmed sites were significantly higher (p < 0.05) than those of the control sites, with figures at the farmed sites ranging from 132 to 1 708 cfu 100 ml?1 for total coliforms, 514 to 5 170 cfu 100 ml?1 Pseudomonas spp. and 14 to 516 cfu 100 ml?1 for Vibrio spp. The results suggested that cage fish farming has increased bacterial loads in the lake water, but has had minimal impact on its physico-chemical quality. 相似文献
8.
Active and passive cation transport and L antigen hertogeneity in low potassium sheep red cells
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Several lines of experimental evidence are presented suggesting that the L antigens in low potassium (LK) sheep red cells are associated with separate Na(+)K(+) pump flux is distinct from the action of anti-L(l) on K(+) leak flux, implying that K(+) leak transport sites may not be converted into active pumps by the L antiserum. Treatment of LK red cells with trypsin completely abolished both the stimulation of K(+) pump flux and the enhancement of the rate of ouabain binding brought about by anti- L. That this effect is due to a total destruction of the L(p) determinant associated with the LK pump was evident from the complete failure of anti-L(p) to bind to trypsinized LK red cells. The L(p) antigen can be effectively protected against the trypsin attack by prior incubation with anti-L, indicating that the sites for antibody binding and trypsin action may be closely adjacent at the structural level. Trypsin treatment, however, did not interfere with anti-L(l) reducing ouabain insensitive K(+) leak influx, nor did it prevent binding of anti-L(ly), the hemolytically active L antibody which is probably identical with anti-L(l). The functional independence of the L(p) and L(l) sites was documented by the observation that anti-L(l) still reduced K(+) leak influx in LK cells with experimentally induced high potassium concentrations, at which K(+) pump flux is fully suppressed, whether or not anti-L(p) was binding to the L(p) antigen associated with the LK pump. 相似文献
9.
Secondary structure maps of long single strands of amplified ribosomal DNA from two closely related species of frogs, Xenopus laevis and X. mulleri, have been compared. The secondary structure pattern of the gene region is identical in both ribosomal DNAs while the patterns in the non-transcribed spacers2 differ. In X. mulleri, the spacer shows an extended region without any secondary structure adjacent to the 28 S ribosomal RNA sequence. In contrast, the same region in the X. laevis spacer has extensive secondary structure. A comparison of secondary structure maps and denaturation maps of these two ribosomal DNAs (Brown et al., 1972) reveals that the portion without secondary structure in the X. mulleri spacer corresponds to an early melting A + T-rich region. As in X. laevis ribosomal DNA, Escherichia coli restriction endonuclease (EcoRI) makes two cuts in each repeating unit of amplified ribosomal DNA from X. mulleri. The position of the cleavage sites is identical in the two species as judged from secondary structure mapping of the two classes of EcoRI fragments generated. The small fragments of X. mulleri ribosomal DNA are homogeneous in size with a duplex molecular weight of 3.0 × 106, and contain about 85% of the 28 S ribosomal RNA gene and about 17% of the 18 S ribosomal RNA gene. The large fragments are heterogeneous in size with molecular weights ranging from 4.2 to 4.9 × 106, and contain the remaining portions of the gene regions and the nontranscribed spacer. Heteroduplexes made between large fragments of different lengths show only deletion loops. The position of these loops indicates that the length heterogeneity resides in the non-transcribed spacer region. Electrophoretic analysis of EcoRI digests of chromosomal ribosomal DNA from X. mulleri demonstrates that this DNA is heterogeneous in length as well. 相似文献
10.
Diagnosis of triple negative breast cancer using expression data with several machine learning tools
Breast cancer is one of the top three commonly caused cancers worldwide. Triple Negative Breast Cancer (TNBC), a subtype of breast cancer, lacks expression of the oestrogen receptor, progesterone receptor, and HER2. This makes the prognosis poor and early detection hard. Therefore, AI based neural models such as Binary Logistic Regression, Multi-Layer Perceptron and Radial Basis Functions were used for differential diagnosis of normal samples and TNBC samples collected from signal intensity data of microarray experiment. Genes that were significantly upregulated in TNBC were compared with healthy controls. The MLP model classified TNBC and normal cells with anaccuracy of 93.4%. However, RBF gave 74% accuracy and binary Logistic Regression model showed an accuracy of 90.0% in identifying TNBC cases. 相似文献