Protozoan parasites including Plasmodia, Leishmania, Trypanosoma, Entamoeba, Trichomonas and others cause diseases in humans and domestic livestock having far-reaching socio-economic implications. They show remarkable
propensity to survive within hostile environments encountered during their life cycle, and the identification of molecules
that enable them to survive in such milieu is a subject of intense research. Currently available knowledge of the parasite
cell surface architecture and biochemistry indicates that sialic acid and its principle derivatives are major components of
the glycocalyx and assist the parasite to interact with its external environment through functions ranging from parasite survival,
infectivity and host-cell recognition. This review highlights the present state of knowledge with regard to parasite sialobiology
with an emphasis on its mode(s) of acquisition and their emerging biological roles, notably as an anti-recognition molecule
thereby aiding the pathogen to evade host defense mechanisms. Published in 2004.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
Calmodulin has been purified in large quantities from goat (Capra hiscus) testis. The procedure includes heat treatment, hydrophobic interaction chromatography, and gel filtration. Goat testis calmodulin closely resembles other mammalian testis calmodulin studied so far. The protein has an extinction coefficient value (E1cm1%
) of 2.09 at 280 nm, a Stokes radius of 23.2 Å at 0.15 M KCl, and a frictional ratio of 1.38. Ca2+, and Tb3+ binding studies demonstrate that the protein has four Ca2+-binding sites with aKd of 52.5 µM. Goat testis calmodulin shows close similarity to other calmodulins in the amino acid composition and in demonstrating an altered migration on SDS/PAGE upon Ca2+ binding. The protein also exhibits anomalously high values for molecular weight and Stokes radius as determined from the analytical gel chromatography and a change in its elution volume with the change of salt concentration in the eluant. These results have been discussed in view of the recently available knowledge from the crystallographic studies of rat testis calmodulin. 相似文献
A portion of the beta-actin mRNA of mammalian cells is believed to lack a poly(A) tail, because of its failure to bind to oligo(dT)-cellulose. S1 mapping and Northern blot analysis of this mRNA shows it to contain a poly(A) sequence of about 60 nucleotides. Only about 20-40 nucleotides are available for interaction with oligo(dT). The rest is masked, presumably by base-pairing with a poly(U) stretch present in the 3' non-coding region of the mRNA. A similar configuration occurs in the bulk of the actin mRNA, which carries a poly(A) tail with sizes ranging from approximately 60 to 200 nucleotides. 相似文献
Adeno-associated virus (AAV) type 2 is an important virus due to its use as a safe and effective human gene therapy vector
and its negative association with certain malignancies. AAV, a dependo-parvovirus, autonomously replicates in stratified squamous
epithelium. Such tissue occurs in the nasopharynx and anogenitals, from which AAV has been clinically isolated. Related autonomous
parvoviruses also demonstrate cell tropism and preferentially replicate in oncogenically transformed cells. Combining these
two attributes of parvovirus tropism, squamous and malignant, we assayed if AAV might replicate in squamous cervical carcinoma
cell isolates. 相似文献
Plasmonic nanoparticles are of great importance owing to their highly responsive ‘localized surface plasmon resonance’ (LSPR) behaviour to self-agglomeration/aggregation leading to the development of various nanosensors. Herein, we demonstrated the definite self-assembly of citrate functionalized silver nanoparticles (AgNPs) into a one-dimensional linear chain in presence of charged lead ions (Pb2+), one of the most toxic heavy metal pollutants. We have explored detail mechanism using a variety of spectroscopic tools and electron microscopy. The self-aggregation of AgNPs leads to the generation of new LSPR modes due to coupling of nearby existing modes. The conclusion of our experimental findings is duly supported by our developed numerical modelling based on the quasi-static approximation that the generated new LSPR modes are solely due to formation of chain-like aggregation of AgNPs. We have also monitored the LSPR spectra in the presence of other metal ions; however, only Pb2+ found to give such unique self-assembled geometry may due to its high interaction affinity with citrate. These findings play a key role for citrate functionalised AgNPs to be used as a low cost highly selective and sensitive lead ion sensor for potential application in industrial lead pollution monitoring. We have further varied several sensor parameters such as AgNPs size, concentration, and the allowed reaction time for it to be practically implemented as an efficient lead sensor meeting the Environmental Protection Agency recommendations.
Graphical abstract
The possible sensing mechanism of citrate-functionalized silver nanoparticles towards Pb2?+?followed by unique chain-like aggregation for potential atmospheric and industrial lead pollution monitoring.
During the last two decades, the DNA barcode development towards microbial community has increased dramatically. DNA barcode development is related to error-free and quick species identification which aid in understanding the microbial biodiversity, as well as the diseases related to microbial species. Here, we seek to evaluate the so-called barcoding initiatives for the microbial communities and the emerging trends in this field. In this paper, we describe the development of DNA marker-based DNA barcoding system, comparison between routine species identification and DNA barcode, and microbial biodiversity and DNA barcode for microbial communities. Two major topics, such as the molecular diversity of viruses and barcode for viruses have been discussed at the same time. We demonstrate the current status and the maker of DNA barcode for bacteria, algae, fungi, and protozoa. Furthermore, we argue about the promises, limitations, and present and future challenges of microbial barcode development. 相似文献