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PubMedDate not supplied

Death of mouse embryos that lack a functional gene for glucose phosphate isomerase.

A null allele of the Gpi-1s structural gene, that encodes glucose phosphate isomerase (GPI-1; E.C. 5.3.1.9), arose in a mutation experiment and was designated Gpi-1sa-m1H. The viability of homozygotes has been investigated. No offspring homozygous for the null allele were produced by intercrossing two heterozygotes, so the homozygous condition was presumed to be embryonic lethal. Embryos were produced by crossing Gpi-1sa/null heterozygous females and Gpi-1sb/null heterozygous males. Homozygous null embryos were identified at different stages of development by electrophoresis and staining either for GPI-1 alone or GPI-1 plus phosphoglycerate kinase (PGK) activity. At 6 1/2 and 7 1/2 days post coitum homozygous null embryos were present at approximately the expected 25% frequency (37/165; 22.4% overall) although at 7 1/2 days the homozygous null embryos tended to be small. By 8 1/2 days most homozygous null embryos were developmentally retarded and had not developed significantly further than at 7 1/2 days; some were dead or dying. By 9 1/2 days the homozygous null conceptus was characterised by a small implantation site that contained trophoblast and often a small amount of extraembryonic membrane. Surviving trophoblast tissue was also detectable at 10 1/2 days. Previous studies have shown that oocyte-coded GPI-1 persists only until 5 1/2 or 6 1/2 days. Survival of homozygous null embryos to 7 1/2 or 8 1/2 days and survival of certain extraembryonic tissue to 10 1/2 days suggests that the homozygous null condition may not be cell-lethal although it is certainly embryo-lethal. Mutant cells that are deficient in glycolysis may use the pentose phosphate shunt to bypass the block in glycolysis created by the deficiency of glucose phosphate isomerase, and/or might be rescued by the transport, from the maternal blood, of energy sources other than glucose (such as glutamine). Either strategy may only permit slow cell growth that would not be adequate to support normal embryogenesis. Transport of maternal nutrients would be more efficient to the trophoblast and extraembryonic membranes and this may help to explain why these tissues survive for longer than the embryo itself. The morphological similarity between homozygous nulls and androgenetic conceptuses, where the trophoblast also survives better than the embryo, is discussed.

Animals↗
PubMed2005

A spectrum of functional genes mobilized after Trichinella spiralis infection in skeletal muscle.

Trichinella spiralis infection causes the transformation of infected muscle cells, which leads to nurse cell formation. To search for the candidate genes responsible for nurse cell formation, cDNA microarray analysis of muscle tissues was performed before and after Trichinella infection. The Atlas mouse 1.2 cDNA expression microarray revealed the expression profiles of 1176 known genes. Out of these, 311 gene expressions were detected in normal and/or infected muscles. After the infection, 184 out of the 311 genes increased in expression by more than 3-fold. These included genes responsible for cell differentiation, proliferation, cell cycle and apoptosis. Thus this study suggested candidate genes for further investigation to dissect the molecular mechanisms of nurse cell formation.

Animals↗
PubMed2000

Structural genomics and its importance for gene function analysis.

Structural genomics projects aim to solve the experimental structures of all possible protein folds. Such projects entail a conceptual shift from traditional structural biology in which structural information is obtained on known proteins to one in which the structure of a protein is determined first and the function assigned only later. Whereas the goal of converting protein structure into function can be accomplished by traditional sequence motif-based approaches, recent studies have shown that assignment of a protein's biochemical function can also be achieved by scanning its structure for a match to the geometry and chemical identity of a known active site. Importantly, this approach can use low-resolution structures provided by contemporary structure prediction methods. When applied to genomes, structural information (either experimental or predicted) is likely to play an important role in high-throughput function assignment.

Animals↗
PubMed2026

Differential expression of neuronal function genes follows a tissue-specific temporal dynamic during Deformed Wing Virus infection in honey bees.

Deformed Wing Virus type A (DWV-A) is one of the primary threats to honeybees (Apis mellifera), significantly impacting their nervous system physiology and behavior. While its neurotropic nature is well-recognized, the temporal dynamics of the neuronal transcriptomic response following oral infection, the natural transmission route, remains poorly understood. In this study, we analyzed gene expression in the heads of worker bees orally inoculated with DWV-A over a 16-day time course (1, 4, 7, 10, 13, and 16 days post-inoculation). RNA-seq analysis at day 10 identified 147 differentially expressed genes associated with different biological processes that are critical to the organism, including cellular metabolism and neuronal activity. RT-qPCR validation revealed a persistent downregulation of key genes related to glutamatergic system (eaat-2, neto, and kainate) and sensory perception-related genes in the antennae. Notably, the simultaneous co-expression of nurse-associated and forager-associated marker genes suggests that DWV-A infection induces an asynchrony in behavioral maturation. Our findings demonstrate that DWV-A disrupts neuronal homeostasis and peripheral sensory perception in a tissue-specific and time-dependent manner, providing a molecular framework to understand the behavioral impairment and the loss of coordination at the colony level.

Animals↗
PubMed2002

Mechanism of action of hammerhead ribozymes and their applications in vivo: rapid identification of functional genes in the post-genome era by novel hybrid ribozyme libraries.

A hammerhead ribozyme was demonstrated to be a metalloenzyme. By controlling the metal-binding ability of the hammerhead ribozyme in the presence or absence of a specific sequence of interest, we engineered an allosterically controllable ribozyme, designated the maxizyme. Hybrid ribozymes were then constructed by coupling the site-specific cleavage activity of a hammerhead ribozyme with the unwinding activity of an endogenous RNA helicase. This leads to extremely efficient cleavage of target mRNA, not only in vitro, but also in vivo, and eliminates one of the major problems arising in the application of ribozymes for cleavage of mRNA in vivo : that many target sites on the RNA were previously inaccessible to cleavage owing to secondary and/or tertiary structure formation. Since hybrid ribozymes can efficiently attack target sites within mRNA, libraries were made of hybrid ribozymes with randomized binding arms, which were then introduced into cells. This procedure made it possible to readily identify the relevant genes associated with a specific phenotype, such as in apoptosis and cancer metastasis pathways. This application of a randomized library of hybrid ribozymes represents a simple, yet powerful, method for the identification of genes associated with specific phenotypes in the post-genome era. Moreover, vector-based siRNA (short-interfering RNA for RNA interference, RNAi) can also be used for the creation of the libraries and for the subsequent confirmation of the identified genes, relevant in the examined phenotype.

Gene Expression Profiling↗
PubMed2006

Use of functional genes to quantify denitrifiers in the environment.

During the last decade, application of molecular methods using cultivation-independent approaches has provided new insights into the composition and structure of denitrifying communities in various environments. However, little is known about their abundance, and quantification is still performed using cultivation-based approaches, which are not only biased by the inability to cultivate of many micro-organisms but also fastidious and time-consuming. Two types of cultivation-independent approaches have recently been developed to quantify denitrifiers. The first type, which is based on the hybridization technique, comprises the use of Southern hybridization and DNA arrays. The second type, based on PCR, comprises the use of MPN (most probable number)-PCR, competitive PCR or real-time PCR. In this review, these different approaches will be presented with examples of their application in environmental studies.

Environment↗
PubMed2004

Correction of ATM gene function by aminoglycoside-induced read-through of premature termination codons.

Approximately 14% of genetic mutations in patients with ataxia-telangiectsia (A-T) are single-nucleotide changes that result in primary premature termination codons (PTCs), either UAA, UAG, or UGA. The purpose of this study was to explore a potential therapeutic approach for this subset of patients by using aminoglycosides to induce PTC read-through, thereby restoring levels of full-length ATM (A-T mutated) protein. In experiments using a modified in vitro cDNA coupled transcription/translation protein truncation test, 13 A-T cell lines carrying PTC mutations in different contexts exhibited read-through expression of ATM fragments, with three of four aminoglycosides tested. In ex vivo experiments with lymphoblastoid cell lines, we used radiosensitivity, radioresistant DNA synthesis, and irradiation-induced autophosphorylation of ATM Ser-1981 to show that the aminoglycoside-induced full-length ATM protein was functional and corrected, to various extents, the phenotype of A-T cells. These results encourage further testing of other compounds in this class, as well as follow up animal studies. Because some A-T patients with 5-20% of normal levels of ATM protein show slower neurological progression, A-T may prove to be a good model for aminoglycoside-induced read-through therapy.

Aminoglycosides↗