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121.
In vertebrates and the cephalochordate, amphioxus, the closest vertebrate
relative, Hox genes are linked in a single cluster. Accompanying the
emergence of higher vertebrates, the Hox gene cluster duplicated in either
a single step or multiple steps, resulting in the four-cluster state
present in teleosts and tetrapods. Mammalian Hox clusters (designated A, B,
C, and D) extend over 100 kb and are located on four different chromosomes.
Reconstructing the history of the duplications and its relation to
vertebrate evolution has been problematic due to the lack of alignable
sequence information. In this study, the problem was approached by
conducting a statistical analysis of sequences from the fibrillar-type
collagens (I, II, III, and IV), genes closely linked to each Hox cluster
which likely share the same duplication history as the Hox genes. We find
statistical support for the hypothesis that the cluster duplication
occurred as multiple distinct events and that the four-cluster situation
arose by a three- step sequential process.
相似文献
122.
Goto Masahiro Ono Tsutomu Nakashio Fumiyuki Hatton T. Alan 《Biotechnology Techniques》1996,10(3):141-144
Summary The extraction behavior of native and heated-denatured -chymotrypsin has been investigated with two different reversed micellar systems. A large difference in the degree of extraction was observed for the native relative to the denatured -chymotrypsin. In particular, mixed reversed micelles formulated with DOLPA (dioleyl phosphoric acid) and AOT show a high selectivity for the active -chymotrypsin. 相似文献
123.
The bean PAL2 and PAL3 promoters confer expression in overlapping sets of tissue types in transgenic tobacco. The PAL3 promoter contains motifs that resemble two AC cis elements which are required for tissue-specific expression of the PAL2 promoter. The functions of these motifs in the PAL3 promoter were determined by analysis of mutated PAL3 promoter-GUS constructs in transgenic tobacco. This revealed that the AC motifs are necessary for tissue-specific expression of the PAL3 promoter. Therefore, a key role is indicated for AC elements, which are Myb-protein binding sites, in regulating tissue-specific expression of the bean PAL gene family. 相似文献
124.
125.
The Olifants River, a tributary of the Limpopo River system, is one of the most polluted rivers in South Africa. In May 2011 the concentrations of metals in fish muscle tissue from two impoundments, Loskop and Flag Boshielo dams, on the Olifants River were measured and a human health risk assessment conducted to investigate whether it was safe to consume Labeo rosae from these impoundments. Labeo rosae is one of the most common pan fish in these impoundments and is readily available to rural communities. Metals are accumulating in the muscle tissue of L. rosae even although the fish populations appear to be healthy. At Loskop Dam all L. rosae analysed exceeded the recommended hazard quotient (HQ) of 1 for antimony, and less than 50% exceeded that for lead. At Flag Boshielo Dam, the recommended HQ was exceeded for lead in less than 50% of L. rosae analysed, and more than 50% exceeded that for antimony. The weekly consumption of 150?g of L. rosae muscle tissue from these impoundments may pose an unacceptable health risk to rural communities. 相似文献
126.
127.
Ruggero Tenni Daniela Tavella Patricia Donnelly Nicola Di Ferrante Leighton Hill Carolyn Leach Dorothy Hatton 《Biochemical and biophysical research communications》1980,92(4):1071-1075
The solubility of collagen synthesized by cultured skin fibroblasts derived from three patients affected by juvenile-onset diabetes mellitus and two normal controls has been compared. The diabetic collagen is much more soluble in 1.0 M NaCl pH 7.5 and in 0.5 M acetic acid. This excessive solubility is partially corrected by the addition to the diabetic cultures of a naturally-occuring flavonoid, (+)-catechin. 相似文献
128.
G. Stokes Hatton 《BMJ (Clinical research ed.)》1901,2(2125):840-844
129.
Catabolism of human transferrin and human asialotransferrin was simultaneously studied in guinea pigs by means of total body radioactivity measurements. Total body activity representing transferrin decreased at a constant rate with an average half-life of 88 h. Decrease of the total body activity representing asialotransferrin exhibited at least two rates; the half-life of the fast initial component averaged at 25 h, whereas the half-life of the slower component averaged at 55 h. Transition occurred between the 50th and 80th hours of the experiments. The complex character of the elimination curves could not be explained by differences in the iron content of asialotransferrin, by the presence of transferrin variants or of denatured protein in the injected material, by residual sialic acid in the preparations, by accumulation of radioactive terminal catabolic products in the body, by an association of asialotransferrin with any other macromolecular plasma constituent, by changing conditions for mass action, or by a continuing return of labeled protein from the extravascular space. Injection of bovine asialotransferrin into guinea pigs did not result in complex total body curves. Analyses of guinea pig tissues demonstrated that human asialotransferrin had marked affinity for the liver and none for the kidney, lung, or spleen. These observations are consistent with the hypothesis that the glycopeptides in human transferrin are heterogeneous in that removal of the sialyl residues exposes structures with different affinities for the hepatic asialoglycoprotein receptor. The precise chemical basis for the metabolic heterogeneity is unknown. 相似文献
130.
Susanne I. Schmidt Hans Jürgen Hahn Tom J. Hatton William F. Humphreys 《Hydrobiologia》2007,583(1):1-19
The exchange of water with groundwater is a key determinant of water quality and faunal assemblage. Water exchange not only
occurs with running waters, but also through percolation, interception (soil, porous alluvium), and evaporation. The aim of
this study was to identify how different types of exchange were related to the groundwater faunal assemblage of an alluvial
aquifer. Hydrological exchange is largely governed by pore space and thus ultimately by geological formation. In the Marbling
Brook catchment of Western Australia the different geological formations did not eventuate in hydrochemically distinct groundwater
zones. The cluster analysis of faunal assemblages revealed five groups within the faunal samples which did not reflect spatial
patterns such as geological, chemical or topographic features. Discriminant analysis showed that these five groups were best
characterized by a range of abiotic features including dissolved oxygen, land-use, and temperature. These variables signal
different types and intensities of exchange with the surface.
Handling editor: K. Martens 相似文献