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1.
mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species 总被引:4,自引:0,他引:4
Reconstructions of the human-African great ape phylogeny by using
mitochondrial DNA (mtDNA) have been subject to considerable debate. One
confounding factor may be the lack of data on intraspecific variation. To
test this hypothesis, we examined the effect of intraspecific mtDNA
diversity on the phylogenetic reconstruction of another Plio- Pleistocene
radiation of higher primates, the fascicularis group of macaque (Macaca)
monkey species. Fifteen endonucleases were used to identify 10 haplotypes
of 40-47 restriction sites in M. mulatta, which were compared with similar
data for the other members of this species group. Interpopulational,
intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of
divergence time and branching order incorporating this variation were
substantially different from those based on single representatives of each
species. We conclude that intraspecific mtDNA diversity is substantial in
at least some primate species. Consequently, without prior information on
the extent of genetic diversity within a particular species, intraspecific
variation must be assessed and accounted for when reconstructing primate
phylogenies. Further, we question the reliability of hominoid mtDNA
phylogenies, based as they are on one or a few representatives of each
species, in an already depauperate superfamily of primates.
相似文献
2.
The Sm-like protein Hfq is required for gene regulation by small RNAs (sRNAs) in bacteria and facilitates base pairing between sRNAs and their mRNA targets. The proximal and distal faces of the Hfq hexamer specifically bind sRNA and mRNA targets, but they do not explain how Hfq accelerates the formation and exchange of RNA base pairs. Here, we show that conserved arginines on the outer rim of the hexamer that are known to interact with sRNA bodies are required for Hfq’s chaperone activity. Mutations in the arginine patch lower the ability of Hfq to act in sRNA regulation of rpoS translation and eliminate annealing of natural sRNAs or unstructured oligonucleotides, without preventing binding to either the proximal or distal face. Stopped-flow FRET and fluorescence anisotropy show that complementary RNAs transiently form a ternary complex with Hfq, but the RNAs are not released as a double helix in the absence of rim arginines. RNAs bound to either face of Hfq quench the fluorescence of a tryptophan adjacent to the arginine patch, demonstrating that the rim can simultaneously engage two RNA strands. We propose that the arginine patch overcomes entropic and electrostatic barriers to helix nucleation and constitutes the active site for Hfq’s chaperone function. 相似文献
3.
4.
Expression of the epithelial cell-specific heterotetrameric adaptor complex AP-1B is required for the polarized distribution of many membrane proteins to the basolateral surface of LLC-PK1 kidney cells. AP-1B is distinguished from the ubiquitously expressed AP-1A by exchange of its single 50-kD mu subunit, mu1A, being replaced by the closely related mu1B. Here we show that this substitution is sufficient to couple basolateral plasma membrane proteins, such as a low-density lipoprotein receptor (LDLR), to the AP-1B complex and to clathrin. The interaction between LDLR and AP-1B is likely to occur in the trans-Golgi network (TGN), as was suggested by the localization of functional, epitope-tagged mu1 by immunofluorescence and immunoelectron microscopy. Tagged AP-1A and AP-1B complexes were found in the perinuclear region close to the Golgi complex and recycling endosomes, often in clathrin-coated buds and vesicles. Yet, AP-1A and AP-1B localized to different subdomains of the TGN, with only AP-1A colocalizing with furin, a membrane protein that uses AP-1 to recycle between the TGN and endosomes. We conclude that AP-1B functions by interacting with its cargo molecules and clathrin in the TGN, where it acts to sort basolateral proteins from proteins destined for the apical surface and from those selected by AP-1A for transport to endosomes and lysosomes. 相似文献
5.
Summary. This paper reports on an original process to synthesize N-carboxyanhydrides, which consists of nitrosating N-carbamoylamino acids with a NO/O2 gas mixture in acetonitrile. The synthesis of several N-carbamoylamino acids of L-lysine was described using potassium cyanate in water. The latter were then nitrosated to yield the corresponding NCA with more or less efficiency. Indeed, the NCA carrying an acid-sensitive protecting group led to a partial deprotection to give the L-lysine NCA salt. The NCA of N-trifluoroacetyl-L-lysine, N-benzyloxycarbonyl-L-lysine and -benzyl-L-glutamate were successfully synthesized with satisfactory yields. Their polymerizability was compared to that of the N-trifluoroacetyl-L-lysine NCA initiated by n-hexylamine in N,N-dimethylformamide. It also showed that this new process of NCA synthesis could be applied to the synthesis of polypeptides and more generally to the protein chemistry. 相似文献
6.
Lui WW Collins BM Hirst J Motley A Millar C Schu P Owen DJ Robinson MS 《Molecular biology of the cell》2003,14(6):2385-2398
The adaptor appendage domains are believed to act as binding platforms for coated vesicle accessory proteins. Using glutathione S-transferase pulldowns from pig brain cytosol, we find three proteins that can bind to the appendage domains of both the AP-1 gamma subunit and the GGAs: gamma-synergin and two novel proteins, p56 and p200. p56 elicited better antibodies than p200 and was generally more tractable. Although p56 and gamma-synergin bind to both GGA and gamma appendages in vitro, immunofluorescence labeling of nocodazole-treated cells shows that p56 colocalizes with GGAs on TGN46-positive membranes, whereas gamma-synergin colocalizes with AP-1 primarily on a different membrane compartment. Furthermore, in AP-1-deficient cells, p56 remains membrane-associated whereas gamma-synergin becomes cytosolic. Thus, p56 and gamma-synergin show very strong preferences for GGAs and AP-1, respectively, in vivo. However, the GGA and gamma appendages share the same fold as determined by x-ray crystallography, and mutagenesis reveals that the same amino acids contribute to their binding sites. By overexpressing wild-type GGA and gamma appendage domains in cells, we can drive p56 and gamma-synergin, respectively, into the cytosol, suggesting a possible mechanism for selectively disrupting the two pathways. 相似文献
7.
8.
Muma JB Lund A Siamudaala VM Munang'andu HM Munyeme M Matope G Nielsen K DJønne B Godfroid J Tryland M Skjerve E 《Journal of wildlife diseases》2010,46(4):1063-1069
One of the diseases of veterinary and public health importance affecting the Kafue lechwe (Kobus leche kafuensis) on the Kafue flats is brucellosis, for which only scant information is available. During the 2003 (October), 2004 (December), and 2008 (July-December) hunting seasons in the Kafue flats, we conducted a study to determine the seroprevalence of Brucella spp. in the Kafue lechwe and to evaluate serologic tests for detection of Brucella spp. antibodies in lechwe. The Rose Bengal Test (RBT), competitive enzyme-linked immunosorbent assay (cELISA), and fluorescence polarization assay (FPA) were used. A total of 121 Kafue lechwe were hunted for disease investigations in 2003, 2004, and 2008 in the Kafue Flat Game Management Area. Of these, 21.6%, (95% confidence interval [CI]: 14.2-29.1%) had detectable antibodies to Brucella spp. The Kafue lechwe in Lochnivar National Park had higher antibody results than those in Blue Lagoon National Park (odds ratio=3.0; 95% CI: 0.94-9.4). Infection levels were similar in females (21.6%) and males (21.7%). Results were similar among RBT, FPA, cELISA tests, suggesting that these could effectively be used in diagnosing brucellosis in the Kafue lechwe. Our study demonstrates the presence of Brucella infections in the Kafue lechwe in two national parks located in the Kafue flats and further highlights the suitability of serologic assays for testing the Kafue lechwe. Because the Kafue lechwe is the most hunted wildlife species in Zambia, hunters need to be informed of the public health risk of Brucella spp. infection. 相似文献
9.
Susan DJ Chapple Anna M Crofts S Paul Shadbolt John McCafferty Michael R Dyson 《BMC biotechnology》2006,6(1):49-15
Background
A variety of approaches to understanding protein structure and function require production of recombinant protein. Mammalian based expression systems have advantages over bacterial systems for certain classes of protein but can be slower and more laborious. Thus the availability of a simple system for production and rapid screening of constructs or conditions for mammalian expression would be of great benefit. To this end we have coupled an efficient recombinant protein production system based on transient transfection in HEK-293 EBNA1 (HEK-293E) suspension cells with a dot blot method allowing pre-screening of proteins expressed in cells in a high throughput manner. 相似文献10.