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At least 271 records · Page 15Linked to original sources
PubMed1999

Identification of thymus specific and developmentally regulated genes by an improved version of the mRNA differential display technique.

During embryogenesis in mouse, the thymus is seeded by waves of hematopoietic stem cells that provide the first peripheral T lymphocytes after birth. It is known that embryo thymocytes and adult thymocytes have different phenotypic and functional features. The identification of genes expressed in the thymus only during embryogenesis would help to understand the molecular basis underlying these characteristics. We used the mRNA differential display technique to compare gene expression between thymus and kidney from embryo (171/2 days) and adult mice. This technique is the method of choice for comparing gene expression because it is able to display rapidly and simultaneously the mRNA complement from several different types of cells. The major drawback of the method is that it leads to the cloning of many false positives and therefore needs a high throughput method to screen for the truly differentially expressed cDNAs. We combined advantages from previously described methods in order to develop a new version of the mRNA differential display technique that is fast, cheap, and reliable. Instead of oligo dT priming, we used random hexameres for the reverse transcription of total RNA and 10-mer primers for the amplification of internal parts of the cDNAs. We obtained reproducible and clean patterns of discrete bands. We were able to easily identify DNAs differentially amplified between embryo and adult tissues (embryo specific; E 58.73), between thymus and kidney (thymus specific; Thy 52.54), or between embryo and adult thymus (embryo thymus specific; E Thy 58.73) cDNA fragments. After reamplification, cloning, and sequencing of these DNA fragments, it appeared that in most cases, one band corresponded to a single DNA sequence. On a northern blot, each of these candidate genes recognized a transcript that is differentially expressed as expected. Thus, we report an optimized, reproducible, and fast mRNA differential display method that overcomes the usual problems met with the originally described technique or its reported modifications.

Animals↗
PubMed1989

Cloning of developmentally regulated genes from Leishmania major and expression following heat induction.

The protozoa Leishmania undergo morphological and biochemical transformation from the promastigote to the amastigote form during their life cycle. To characterize this transformation process, we constructed a cDNA library for the promastigote stage of Leishmania major and used differential cDNA hybridization to identify cDNA sequences expressed at different abundance in promastigotes or amastigotes of L. major. P100/11E is a single copy gene whose 1600-nucleotide mRNA is enriched in promastigotes. P101/10 is a repeated gene whose 3300-nucleotide transcript is enriched in amastigotes. These developmentally regulated genes are not linked in the genome of L. major and are located on separate chromosome bands. The abundance of the P101/10 transcript increases severalfold during the transformation process at 37 degrees C in vitro and is thermally induced within 3 h after transfer of promastigotes from 27 to 37 degrees C. Examination of beta-tubulin gene expression showed that the relative abundance of the 3400-nucleotide beta-tubulin RNA is decreased at 37 degrees C in vitro. Our results indicate that the expression of two developmentally regulated genes of L. major is controlled at the level of mRNA abundance and provide direct evidence that thermal induction plays a general role in regulating gene expression in Leishmania.

Animals↗
PubMed2002

OSTF1: a HD-GL2 family homeobox gene is developmentally regulated during early embryogenesis in rice.

In many eukaryotic organisms, homeobox genes are important regulators that specify the cell fate and body plan in early embryogenesis. In this study, a gene designated OSTF1 (Oryza sativa transcription factor 1) encoding a homeodomain protein in rice was isolated and characterized. The encoded OSTF1, although sharing only approximately 51% sequence identity with other HD-GL2 members, contains four characteristic motifs (an N-terminal acidic region, a homeodomain, a truncated leucine zipper, and a START domain). OSTF1 was detected as a single copy gene in rice. The transcripts were absent in young panicle or mature spikelet before anthesis, but appeared very early in the pollinated grain with a transient profile. In vegetative tissues examined, expression was only detectable in root. In situ hybridization analysis on developing grains revealed that OSTF1 was strongly and uniformly expressed in the embryo at the globular stage and preferentially localized to the protoderm at 3-6 d after pollination. Expression was also detectable in the integument and throughout the endosperm. Although OSTF1 is not closely related to the remaining HD-GL2 members in sequences, this gene exhibits an analogous epidermis-preferential expression pattern.

Amino Acid Sequence↗
PubMed2000

Isolation and analysis of a new developmentally regulated gene from amastigotes of Leishmania mexicana mexicana.

Leishmania differentiates from the promastigote to the amastigote stage during its digenetic life cycle. Characterization of the developmentally regulated genes during that process would help to elucidate the mechanisms of gene regulation. In this study, specific fragments of mRNAs from the amastigote stage of L. mexicana mexicana were discriminated from those of the promastigote and metacyclic stages by differential display. This technique combined with spliced-leader polymerase chain reaction allowed isolation of the complete gene VG7A5. The sequence of this gene did not align with any published L. mexicana sequence. More than one copy of this gene was identified in the genome by Southern-blot analysis and was transcribed exclusively in the amastigote stage. At 20 bp upstream from the splice AG site it has a trans-splicing polypyrimidine tract. The gene encodes the subcellular localization motifs 5'-GGACT and AAGCT-3' in the 3' untranslated region of the mRNA. The open reading frame of the gene VG7A5 predicts a polypeptide of 587 amino acid residues that has a KGRR amidation motif near its carboxyl terminus, suggesting that in the mammalian host this protein may be involved in the process of acute inflammation.

5' Untranslated Regions↗
PubMed2001

Differential expression of the fibroin gene in developmental stages of silkworm, Antheraea mylitta (Saturniidae).

Fibroin gene expression during the larval developmental stages of the Saturniid silkworm, Antheraea mylitta, was analyzed. Northern blot analysis of larval silk gland total RNA using the fibroin gene as a probe showed that fibroin is expressed in the intermoult stages and repressed during the moulting stages. Abundance of fibroin transcripts gradually increased from the third to fifth intermoult stage, reaching a peak in the fifth intermoult. Transcripts declined during the early spinning stage. Western blot analysis of fibroin protein production with anti-fibroin antibody confirmed the differential fibroin expression, in accordance with fibroin mRNA synthesis. Dot blot hybridization of genomic DNA isolated from each larval developmental stage with the labelled fibroin gene showed that at the genomic level, the relative concentration of the fibroin gene was constant throughout the developmental stages. Our data confirm that fibroin gene expression in A. mylitta, like in B. mori, is transcriptionally controlled and shows differential temporal variations.

Animals↗
PubMed1984

Accumulation of alpha-mannosidase-1 in Dictyostelium discoideum requires many developmentally essential genes.

alpha-Mannosidase-1, one of the earliest known developmentally controlled gene products in the cellular slime mold Dictyostelium discoideum, accumulates intracellularly during both axenic growth and development. The accumulation of alpha-mannosidase-1 activity prematurely ceases in all of 125 randomly isolated aggregation-deficient mutants at discrete times in development resulting in significantly reduced levels of cellular enzyme activity. This suggests that, unlike other developmentally controlled enzymes in this organism, the continued accumulation of alpha-mannosidase-1 activity is controlled by a large number of genes essential for early development. alpha-Mannosidase-1 misregulation and the aggregation-deficient phenotype are caused by the same mutation since (1) morphological revertants exhibit a coreversion to both fruiting ability and wild-type alpha-mannosidase-1 accumulation and (2) normal enzyme accumulation depends on the ability to aggregate and ultimately fruit in a conditional aggregation-deficient mutant. This type of regulation does not appear to be due to differences in enzyme secretion or changes in the overall rate of total protein synthesis. Aggregation-deficient mutants continue to synthesize protein beyond the time in development at which alpha-mannosidase-1 accumulation ceases. Our studies indicate that most of the 50-125 genes required for aggregation in Dictyostelium are also required for the normal accumulation of alpha-mannosidase-1 activity.

Dictyostelium↗
PubMed1995

Non-viral gene transfer: applications in developmental biology and gene therapy.

The main limitation of non-viral gene transfer methods is their relatively low efficiency in vivo. However, a number of approaches can be taken to improve their performances, whether the aim is studying gene function during development or employing these techniques for gene therapy. Three non-viral delivery systems that we have been particularly involved in in developing are described: the cationic lipid, dioctadecylamidoglycylspermine (DOGS), the cationic polymer polyethylenimine (PEI) and free DNA. The application of each of these methods to different in vivo situations is presented: the use of DOGS for transfecting embryos and the developing mammalian nervous system; the recent application of PEI to the nervous system; and how naked DNA can be employed for transfecting different muscles and brain. The relative efficiencies are compared on the basis of luciferase reporter gene expression assessed in each tissue with the most appropriate vector system. Finally, the perspectives for constructing composite vectors combining safety and efficiency are considered briefly.

Animals↗
PubMed1989

Isolation and characterization of recombinant cDNA clones corresponding to developmentally regulated genes in pig liver.

To identify clones that corresponded to developmentally regulated genes in pig liver, recombinant cDNA libraries were constructed from early fetal (d 40), late fetal (d 110) and adult liver mRNA. Each library was screened by probing with total cDNA prepared from mRNA at different stages of development. Nine clones that gave distinct developmental patterns when hybridized to liver RNA isolated from various stages of development were subsequently isolated and partially sequenced. The cognate proteins for seven of these clones were identified by searching a national DNA sequence resource (Bionet) for similar sequences. Clones hybridizing to mRNA that was most abundant early in development were alpha fetoprotein, alpha 1 antiprotease, alpha globin and an unidentified clone. The mRNA for beta and gamma fibrinogen were most abundant perinatally. The abundance of mRNA for albumin, haptoglobin and a second unidentified clone was low in fetal liver, but increased to adult levels between birth and 3 d of age. These clones provide probes to study the relationship between factors affecting fetal growth and expression of specific genes throughout the development.

Animals↗
PubMed1993

Altering the spatial determinations in the mouse embryos by manipulating the Hox genes.

Developmental genetics in Drosophila led to the isolation of the homeotic genes which are involved in the cellular positional information. In vertebrates, homologous genes have been characterized and play similar roles in the spatial determination. However, the subtle mechanisms by which positional identity is specified by the Hox genes co-expression are little known. The Hoxc-8 null mutation can induce homeosis at the anterior margin of Hoxc-8 expression, where the mosaicism observed suggests that, at least in the segmented paraxial mesoderm, the number of cells expressing a Hox gene is a determinant parameter. A combinatorial model is also suggested by several genetic experiments where the level of Hox genes expression is modified. Expression of some related Hox genes in Hoxc-8 homozygous mutants is not altered, suggesting the absence of genetic interregulations between these genes.

Animals↗
PubMed1989

Developmentally regulated gene from Leishmania encodes a putative membrane transport protein.

We have cloned a developmentally regulated gene from the parasitic protozoan Leishmania enrietti. The mRNA from this gene accumulates to a much higher level in the promastigote stage of the parasite life cycle that lives in the gut of the insect vector than in the amastigote stage of the parasite that lives inside the macrophages of the mammalian host. The predicted protein encoded by this gene is homologous to the human erythrocyte glucose transporter and to several sugar-transport proteins from Escherichia coli. These structural similarities strongly suggest that the cloned gene encodes a membrane transport protein that is developmentally induced when the parasite enters its insect vector. Regulated membrane transporters may be required for the parasite to adapt to the environment of the insect gut.

Amino Acid Sequence↗
PubMed1989

Molecular analysis of a developmentally regulated gene required for Dictyostelium aggregation.

We have previously shown that the developmentally regulated gene D2 is induced during aggregation by pulses of cAMP, which act via the cell surface receptor and consequent signal transduction pathways (W. Rowekamp and R.A. Firtel, 1980, Dev. Biol. 79, 409-418; S.K.O. Mann and R.A. Firtel, 1987, Mol. Cell. Biol. 7, 458-469; S.K.O. Mann, C. Pinko, and R.A. Firtel, 1988, Dev. Biol., in press). In this manuscript, we compare the complete derived amino acid sequence for D2 to two cloned and sequenced eukaryotic esterases and examine the requirement of the D2 gene product for development. Amino acid sequence data comparisons suggest that D2 encodes a serine esterase with strong sequence identity to Torpedo acetylcholine esterase and a Drosophila esterase. The protein has a putative leader sequence, suggesting that it is shunted into vesicles. Using an antisense gene construct driven by a Discoidin I promoter, whose transcriptional activity depends on the growth conditions of the cells, we show that inhibition of D2 mRNA accumulation results in an abnormal developmental program that includes the absence of normal streaming and incomplete aggregate formation and subsequent development. We suggest that D2 encodes an esterase function required for proper aggregation and subsequent development.

Acetylcholinesterase↗
PubMed1987

Expression of many developmentally regulated genes in Myxococcus depends on a sequence of cell interactions.

Certain developmental mutants of Myxococcus xanthus can be complemented extracellularly by wild-type cells. These mutants behave as if they are defective in cell-cell interactions that are required for development. There may be several different interactions because the mutants belong to four extracellular complementation groups (A, B, C, and D). We report here that B- and C- mutations change the pattern of gene expression during Myxococcus development as detected by transcriptional fusions to lacZ mediated by Tn5 lac. The mutant C locus reduced or abolished developmental beta-galactosidase expression from 15 lac fusions that normally begin to be expressed in wild-type cells after 6 hr of development. Expression of these C-dependent lac fusions was restored to C- mutants by adding wild-type cells. The C- mutation did not affect the expression of 10 lac fusions that normally begin to be expressed before 6 hr of development, indicating that the C-mediated cell-cell interaction is required beginning at about 6 hr of development. Cells require the B+ function very early in development because a B- mutation reduced or abolished developmental beta-galactosidase expression from all 26 lac fusions tested, including some that normally begin to be expressed at the onset of development. In a C- mutant and in a B- mutant, some lac fusions responded with reduced beta-galactosidase expression, whereas other fusions, which would normally begin beta-galactosidase expression at about the same time during development, expressed no beta-galactosidase, indicating that developmental genes within a given temporal class display different sensitivities to the absence of cell-cell interactions. Requirements for B+ and C+ function, as well as the previously described A+ function, appear to lie on the same developmental pathway.

DNA Transposable Elements↗
PubMed2006

A framework to monitor environment-induced major genes for developmental trajectories: implication for a prenatal cocaine exposure study.

Whether there are specific genes involved in response to different environmental agents and how such genes regulate developmental trajectories during lifetime are of fundamental importance in health, clinical and pharmaceutical research. In this article, we present a novel statistical model for monitoring environment-induced genes of major effects on longitudinal outcomes of a trait. This model is derived within the maximum likelihood framework, incorporated by mathematical aspects of growth and developmental processes. A typical structural model is implemented to approximate time-dependent covariance matrices for the longitudinal trait. This model allows for a number of biologically meaningful hypothesis tests regarding the effects of major genes on overall growth trajectories or particular stages of development. It can be used to test whether and how major genetic effects are expressed differently under altered environmental agents. In a well-designed case-control study, our model has been employed to detect cocaine-dependent genes that affect growth trajectories for head circumference during childhood. The detected gene triggers significant effects on growth curves in both cocaine-exposed (case) and unexposed groups (control), but with different extents. Significant genotype-environment interactions due to this so-called environment-sensitive gene are promising for further studies toward its genomic mapping using polymorphic molecular markers.

Adult↗
PubMed2001

Analyses of mrp genes during Myxococcus xanthus development.

Myxococcus xanthus is a gram-negative soil bacterium that undergoes development under starvation conditions. Our previous study identified a new genetic locus, mrp, which is required for both fruiting body formation and sporulation. The locus encodes two transcripts: mrpAB, which consists of a histidine kinase and an NtrC-like response regulator, and mrpC, a cyclic AMP receptor protein family transcription activator. In this study, we used genetic and biochemical analyses to investigate the possible interactions between the mrp genes and other known developmental genes and events. These studies show that the mrp genes possibly function after A-signaling and (p)ppGpp but before C-signaling and that they regulate various early and late developmental genes and events.

Bacterial Proteins↗