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Stage-specific Expression (stage-specific + expression)
Selected AbstractsStage-specific Expression of Leukaemia Inhibitory Factor and its Receptor in Rabbit Pre-implantation Embryo and Uterine Epithelium During Early PregnancyREPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2004T Lei Contents Leukaemia inhibitory factor (LIF) has been shown to play an important role in the development and implantation of blastocysts in mice. In the current study, the reverse transcription,polymerase chain reaction (RT-PCR) was employed to examine the expression patterns of LIF and its receptor (LIFR) genes in rabbit embryos during pre-implantation development, and the uterine expression of LIF and LIFR was also evaluated by Western blotting. Transcripts for LIFR were detected within morula and blastocyst-stage embryos, while the LIF mRNA was only found in blastocysts (from early to fully expanded blastocoel cavities), indicating that embryo-derived LIF can act in an autocrine manner on the process of blastocyst formation. The expression levels of LIF and LIFR in uterine epithelium were gradually increased during pre-implantation period and reached their highest levels on days 6.5 of pregnancy, just before the time of blastocyst implantation, suggest that paracrine LIF circuit should exist between the endometrium and the early embryos, which may be involved in the embryo-maternal dialogue and important for the blastocyst implantation. The data present here show the stage-specific and dynamic expression patterns of LIF and LIFR, both in embryos and endometrium, during early pregnancy in rabbits, which indicated that LIF might play an important role in the pre-implantation development and subsequent implantation of rabbit embryos. [source] Stage-specific expression of Caenorhabditis elegans ribonuclease H1 enzymes with different substrate specificities and bivalent cation requirementsFEBS JOURNAL, Issue 2 2006Hiromi Kochiwa Ribonuclease H1 (RNase H1) is a widespread enzyme found in a range of organisms from viruses to humans. It is capable of degrading the RNA moiety of DNA,RNA hybrids and requires a bivalent ion for activity. In contrast with most eukaryotes, which have one gene encoding RNase H1, the activity of which depends on Mg2+ ions, Caenorhabditis elegans has four RNase H1-related genes, and one of them has an isoform produced by alternative splicing. However, little is known about the enzymatic features of the proteins encoded by these genes. To determine the differences between these enzymes, we compared the expression patterns of each RNase H1-related gene throughout the development of the nematode and the RNase H activities of their recombinant proteins. We found gene-specific expression patterns and different enzymatic features. In particular, besides the enzyme that displays the highest activity in the presence of Mg2+ ions, C. elegans has another enzyme that shows preference for Mn2+ ion as a cofactor. We characterized this Mn2+ -dependent RNase H1 for the first time in eukaryotes. These results suggest that there are at least two types of RNase H1 in C. elegans depending on the developmental stage of the organism. [source] Molecular cloning and sequence analysis of an ascidian egg ,-N-acetylhexosaminidase with a potential role in fertilizationDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2003Ryo Koyanagi ,-N-Acetylhexosaminidase, which is found almost ubiquitously in sperm of invertebrates and vertebrates, supposedly mediates a carbohydrate-based transient sperm,egg coat binding. In ascidians and mammals, ,-hexosaminidase released at fertilization from eggs has been proposed to modify sperm receptor glycoproteins of the egg envelope, thus setting up a block to polyspermy. Previously, it was shown that in potential sperm receptor glycoproteins of the ascidian Phallusia mammillata, N-acetylglucosamine is the prevailing glycoside residue and that the egg harbors three active molecular forms of ,-hexosaminidase. In the present study, P. mammillata,-hexosaminidase cDNA was isolated from an ovarian cDNA library and characterized. The deduced amino acid sequence showed a high similarity with other known ,-hexosaminidases; however, P. mammillata,-hexosaminidase had a unique potential N-glycosylation site. A phylogenetic analysis suggested that P. mammillata,-hexosaminidase developed independently after having branched off from the common ancestor gene of the chordate enzyme before two isoforms of the mammalian enzyme appeared. In situ hybridization revealed stage-specific expression of ,-hexosaminidase mRNA during oogenesis in the oocyte and in the accessory test and follicle cells. This suggests that the three egg ,-hexosaminidase forms are specific for the oocyte, test cells and follicle cells. [source] The VpreB1 enhancer drives developmental stage-specific gene expression in vivoEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2003Steve Licence Abstract In adult mice, the VpreB genes are expressed in bone marrow progenitor (pro-) and precursor (pre-) B,cells. As part of the pre-B,cell receptor, the proteins are crucial for the proliferation of these cells and consequently normal B,lymphocyte development. Using cell lines, we identified a lineage- and developmental-stage-specific VpreB1 enhancer. Here, we analyze its specificity in vivo by generating transgenic mice in which expression of a reporter gene (human CD122) is regulated by the VpreB1 enhancer in the context of its own promoter. All transgenic lines expressed thereporter gene in the bone marrow in a copy number-independent manner, whereas expression levels were integration site-dependent. While the enhancer is not tissue specific, within the B,cell lineage the expression pattern of human CD122 mimicked that of endogenous VpreB1. Thus, low levels were detected in pro-B,cells, high levels in pre-BI and slightly lower levels in pre-BII cells; no expression was detected in immature/mature B,cells. Furthermore, when in vitro cultured transgenic pre-B,cells differentiated into immature B,cells there was concomitant down-regulation of human CD122 andendogenous VpreB1. Thus the VpreB1 enhancer is sufficient to ensure developmental stage-specific expression of a reporter gene in B,lymphocytes in vivo. [source] Expression and characterization of ,-glucosidase III in the dwarf honeybee, Apis florea (Hymenoptera: Apoidea: Apidae)INSECT SCIENCE, Issue 4 2007CHANPEN CHANCHAO Abstract Alpha-glucosidase is synthesized in the hypopharyngeal glands located in the head of worker bees including Apis florea. To analyze the developmental stage-specific expression of the ,-glucosidase gene in A. florea, total RNA was isolated from eggs, and the heads of nurse and forager bees. By reverse transcription polymerase chain reaction (RT-PCR), it was shown that the highest expression levels of the ,-glucosidase III gene, in the three examined developmental stadia, were found in forager bees, with much lower expression levels in nurse bees and no detectable expression in eggs. A complete ,-glucosidase III cDNA was obtained by RT-PCR and sequenced. The 1 701 bp cDNA nucleotide sequence and the predicted 567 amino acids it encodes were assayed by BLASTn, BLASTp and BLASTx programs and revealed a 95% and 94% similarity to the A. mellifera,-glucosidase III gene at the DNA and amino acid sequence levels, respectively. For purification of the active encoded enzyme, forager bee heads were homogenized in sodium phosphate buffer solution and the crude extract (0.30 U/mg) sequentially precipitated with 95% saturated ammonium sulfate (0.18 U/mg), and purified by DEAE cellulose ion exchange chromatography (0.17 U/mg), and gel filtration on Superdex 200 (0.52 U/mg). After resolution through sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a single enzymically active band (73 kDa) was identified from renatured substrate gels. Excision of this band, elution of the protein and tryptic peptide digestives identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) revealed six matching masses to the A. mellifera (Q17958) and predicted A. florea,-glucosidase III protein with 12% coverage, supporting the probable purification of the same ,-glucosidase III protein as that encoded by the cloned cDNA. [source] Host,pathogen protein interactions predicted by comparative modelingPROTEIN SCIENCE, Issue 12 2007Fred P. Davis Abstract Pathogens have evolved numerous strategies to infect their hosts, while hosts have evolved immune responses and other defenses to these foreign challenges. The vast majority of host,pathogen interactions involve protein,protein recognition, yet our current understanding of these interactions is limited. Here, we present and apply a computational whole-genome protocol that generates testable predictions of host,pathogen protein interactions. The protocol first scans the host and pathogen genomes for proteins with similarity to known protein complexes, then assesses these putative interactions, using structure if available, and, finally, filters the remaining interactions using biological context, such as the stage-specific expression of pathogen proteins and tissue expression of host proteins. The technique was applied to 10 pathogens, including species of Mycobacterium, apicomplexa, and kinetoplastida, responsible for "neglected" human diseases. The method was assessed by (1) comparison to a set of known host,pathogen interactions, (2) comparison to gene expression and essentiality data describing host and pathogen genes involved in infection, and (3) analysis of the functional properties of the human proteins predicted to interact with pathogen proteins, demonstrating an enrichment for functionally relevant host,pathogen interactions. We present several specific predictions that warrant experimental follow-up, including interactions from previously characterized mechanisms, such as cytoadhesion and protease inhibition, as well as suspected interactions in hypothesized networks, such as apoptotic pathways. Our computational method provides a means to mine whole-genome data and is complementary to experimental efforts in elucidating networks of host,pathogen protein interactions. [source] | ||||||||||||||||