PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Transient expression”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources
PubMed1985

Transient expression of glial fibrillary acidic protein in developing oligodendrocytes in vitro.

Expression of galactocerebroside (GC) and glial fibrillary acidic protein (GFAP) was studied in oligodendrocyte-enriched cultures of newborn mouse brains. In the cultures, GC was detectable as early as 1 day in vitro (1-DIV). Using double immunofluorescence labeling, some GC-positive cells were also stained homogeneously by the anti-GFAP serum. The intensity of GFAP staining increased until 9-DIV when the GC-positive cells revealed the typical morphology of oligodendrocytes, and the GFAP staining faded thereafter. The GFAP staining pattern of the GC-positive cells was not changed upon exposure to demecolcine, even though the GC-negative, GFAP-positive astrocytes showed perinuclear aggregation of GFAP. No intermediate filaments were observed in the oligodendrocytes by electron microscopy. The results suggest that the oligodendrocytes may have soluble GFAP in a certain period of early development.

Animals↗
PubMed1986

Transient expression of neurofilament-like (RT97) immunoreactivity in cerebellar granule cells.

The expression of the 200-kDa neurofilament subunit in developing rat cerebellar granule cells in vivo and in vitro was examined by immunocytochemistry and immunoblotting. Granule cells in vitro were found to express neurofilament-like immunoreactivity. In cryostat sections, neurofilament immunoreactivity was evident between P6 and P13 as a band of staining in the molecular layer indicative of staining of parallel fibres. No labelling of parallel fibres was seen at P18 or in adult animals.

Animals↗
PubMed1988

Transient expression of somatostatin receptors in the rat cerebellum during development.

Somatostatin and somatostatin receptors have not been identified in adult rat cerebellum. In contrast, during the development, somatostatin-containing neurons have been visualized in the deep layers of the cerebellum. The present study shows that during ontogenesis, somatostatin receptors are present in close association with the external granule cell layer of the cerebellum. No correlation was found between the location of immunoreactive somatostatin and the distribution of somatostatin receptors. The disappearance of somatostatin receptors, from postnatal day 13 to 23, was concomitant with the involution of the external germinal layer.

Age Factors↗
PubMed1993

Many spinal cord cells transiently express low molecular weight forms of glutamic acid decarboxylase during embryonic development.

At early developmental stages in the rat spinal cord (embryonic day 13), when neuronal progenitors are still proliferating, most differentiating neurons express truncated forms of glutamic acid decarboxylase (GAD) (approximately 25 kDa) which are the products of alternative splicing of the GAD67 gene. These truncated proteins do not appear to synthesize gamma-aminobutyric acid (GABA). The amino acid is detected in cells only after alternative splicing of the GAD67 gene generates a full-length, 67 kDa enzymatically active form of GAD. Both the 67 kDa GAD and GABA colocalize and appear diffusely distributed in the cytoplasm of embryonic neurons. GABA does not appear associated with synaptic vesicles until after birth, when its intracellular distribution becomes punctate and it colocalizes with synaptophysin. At this time, it also colocalizes with an immunologically distinct 65 kDa GAD protein encoded by a second GAD gene (GAD65). Expression of different GAD-related proteins with distinct intracellular distributions during development suggests that GABA, the product of these enzymes, may have trophic or metabolic roles during spinal cord differentiation.

Animals↗
PubMed1995

c-fos and jun-B mRNAs are transiently expressed in fetal rodent suprachiasmatic nucleus following dopaminergic stimulation.

We examined the time-course of expression of c-fos and jun-B mRNAs in the fetal rat suprachiasmatic nuclei (SCN) following maternal cocaine injection on gestational day 20. Both c-fos and jun-B mRNA levels increased within 20 min, peaked at 40 min and declined to baseline by 120 min after cocaine treatment (30 mg/kg). In mice, the D1-dopamine agonist, SKF 38393, induced c-fos and jun-B mRNAs in the fetal SCN and striatum. Regulated expression of immediate early genes in the fetal SCN may play a role in entrainment of the fetal clock.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1996

Transient expression of lyn gene in Purkinje cells during cerebellar development.

Expression of the lyn gene, a member of sarcoma proto-oncogene family, was analyzed immunohistochemically during cerebellar development in the rat. Lyn immunoreactivity was intense in axons, dendrites and somata of Purkinje cells from gestational day 18 to postnatal day 15 and then decreased. lyn gene expression clearly followed the appearance and the maturation of dendritic arbors. A rapid decrease in Lyn protein, after the 18th postnatal day, left only a few scattered positive Purkinje cell somata in the adult. External and undifferentiated internal granule cells were weak in Lyn immunoreactivity but gradually increased during development. Clusters of positive granule cells were found along the Purkinje cell layer with parasagittal bands crossing the granular layer by 21 days. These bands persisted into adulthood. Cerebellar nuclei lacked immunoreactivity in early development but only fastigial neurons began to acquire lyn gene expression by the 15th postnatal day. The corresponding appearance of the lyn gene expression and the formation of Purkinje cell dendritic arbors suggests that Lyn protein is involved in dendrogenesis. On the other hand, the late onset of immunoreactivity in fastigial neurons and granule cells implies a role in cell maintenance.

Animals↗
PubMed1995

Transient expression mediated by the Trypanosoma cruzi rRNA promoter.

Plasmid constructs containing a putative Trypanosoma cruzi rRNA promoter and transcription start point upstream from the bacterial chloramphenicol acetyltransferase (CAT) reporter gene were transfected into cultured T. cruzi epimastigotes to verify the presence of a promoter activity. Constructs bearing the putative promoter and a 3' trans-splicing acceptor site in the proper orientation yielded approx. two orders of magnitude greater CAT expression than that previously observed with the T. cruzi spliced leader (SL) gene promoter. In contrast, similar constructs lacking the known 3' splice site yielded reduced but readily measurable expression suggesting that sequences near the promoter may function as cryptic 3' splice sites. A repeated sequence upstream from the putative basal rRNA promoter in a position analogous to rRNA gene enhancer elements in other eukaryotes did not enhance expression from the T. cruzi rRNA promoter. Finally, these constructs were functional in some but not all T. cruzi isolates, and were inactive in other kinetoplastid species, suggesting that the T. cruzi rRNA promoter may have a limited host range.

Animals↗
PubMed1987

Postnatal transient expression of long-lasting descending inhibitory effect on spinal reflexes in the rat.

In the spinal cord isolated from neonatal rats, stimulation of the ipsilateral lateral column at the thoracic level strongly inhibited monosynaptic segmental reflex in the lumbar cord for about 60 s. The descending inhibition was not associated with any changes in the membrane potential or conductance in lumbar motoneurons when the excitatory postsynaptic potentials in response to stimulation of the dorsal root were depressed. The descending inhibition was diminished with age and could not be detected at 5 months of age. It is suggested that certain inhibitory pathways in the descending spinal tract are rearranged during postnatal development of rats.

Age Factors↗
PubMed1992

Transient expression of estrogen-receptor-like immunoreactivity (ER-LI) in the facial nucleus of the neonatal rat.

Estrogen receptor-like immunoreactivity (ER-LI) was detected in the medial subnucleus of the facial nucleus by immunocytochemistry in both male and female neonatal rats, but not in the adult rat. Identity of the motoneurons in this subnucleus projecting to the corresponding facial muscles and the cells with ER-LI positive signals was examined by retrograde tracing. The majority of the cells marked with the tracer did not carry ER-LI signals.

Animals↗
PubMed1993

Transient expression of calretinin during development of chick cerebellum. Comparison with calbindin-D28k.

Calcium ions play a critical role in neural development. Insights into the ontogeny of Ca2+ homeostasis were gained by investigating the developmental expression of two E-F hand calcium-binding proteins. Calretinin and calbindin were monitored through their immunoreactivity in the developing chick cerebellum (from E6 to E20). Calbindin was detected from E13 and in Purkinje cells only. Intensity of labelling increased with Purkinje cell development. Calretinin presented a transitory immunoreactivity between E11 and E20 in the internal granular cell layer. This cell layer contains cells which will differentiate into Golgi and granular cells which are calretinin-negative in adult chick cerebellum. Calretinin immunoreactivity presented a peak (both in number of cells and in intensity) at E15 and fell dramatically after E20 while calbindin immunoreactivity was restricted to the Purkinje cells and increased with the development of these cells.

Animals↗
PubMed1990

Transient expression of somatostatin mRNA in the auditory system of neonatal rat.

Postnatal changes of preprosomatostatin mRNA expression in the rat auditory system were examined using in situ hybridization histochemical techniques. It was found that during postnatal days 1 and 2 most of the neurons in the dorsal and ventral cochlear nuclei, and large numbers of neurons in the inferior colliculus, paralemniscal nucleus, and lateral lemniscal nucleus, expressed somatostatin mRNA with a strong intensity. During postnatal development a marked decrease in the number and intensity of neurons expressing somatostatin mRNA was seen. These findings suggested that somatostatin was actively produced in the cochlear nuclei at a very early stage but that production later became reduced or ceased during postnatal ontogeny.

Aging↗
PubMed1996

Transient expression of the mitogen-activated protein kinase phosphatase MKP-1 (3CH134/ERP1) in the rat brain after limbic epilepsy.

The immediate early gene-encoded enzyme, MAP kinase phosphatase 1 (MKP-1), is thought to be a key element in controlling cellular signalling pathways activated by MAP kinases. Since MAP kinase have been demonstrated to participate in neuronal stimulus-transcription coupling following seizure activity, the present study investigated the induction of MKP-1 in the rat brain after limbic epilepsy. MKP-1 expression was studied with a polyclonal antiserum by Western blots, immunocytochemistry and immuno-electron microscopy at different time periods between 1 and 24 h after kainic acid-induced limbic seizures. MKP-1 induction was identified in dentate granule cells of the hippocampus but not in pyramidal neurons, furthermore in neurons of the outer layers of the neocortex, as well as in neurons of the lateral nucleus of the bed of the stria terminalis. Immuno-electron microscopy demonstrated that MKP-1 was localized in the neuronal nucleus, where the substrate of MKP-1, activated MAP kinases, are also found. In view of the restricted areas of MKP-1 expression and the widespread areas of altered MAP kinases activity it can be concluded that in the majority of CNS populations other mechanisms than MKP-1 induction are responsible for the shut-off of MAP kinases following seizure activity. MKP-1 may contribute in the specific subpopulations where it is induced to the post-translational control of inducible transcription factors of the fos, jun and myc family.

Animals↗
PubMed1984

A cell surface antigen present on cultured cerebellar neurones appears to be transiently expressed during cerebellar development in the rat.

A monoclonal antibody has been produced from a fusion of NSO myeloma cells and splenocytes from a mouse immunized with cultures from early postnatal rat cerebellum. The binding of this antibody designated 69A1 is concentrated in the molecular layer of the developing rat cerebellum during the first two weeks postnatally but falls below the level of detection during the third week. Immunoelectron microscopy has shown antibody binding in the molecular layer to be confined to the parallel fibres of the granule neurones. The disappearance of binding coincides with a period during which the formation of new parallel fibres is completed and rapid synaptogenesis within the molecular layer begins.

Animals↗
PubMed1985

Transient expression of the chloramphenicol acetyltransferase gene in cultured mosquito cells.

A recombinant plasmid in which the bacterial chloramphenicol acetyltransferase (CAT) gene is under the control of the Drosophila heat-shock protein (hsp) 70 promoter has been introduced into cultured mosquito (Aedes albopictus) cells using 1,5-dimethyl-1,5-diazaundecamethylene polymethobromide (polybrene) and dimethylsulfoxide (DMSO). CAT activity was induced by incubating transfected cells at 37 degrees C, and high levels of enzyme activity were maintained for more than 24 h after the temperature shock. Transfected DNA was maintained in the cells for at least 4 days. These experiments document an effective method for introducing purified DNA into cultured mosquito cells.

Acetyltransferases↗
PubMed1988

Transient expression in mammalian cells of the bacterial reporter gene encoding mercuric reductase: effects of various regulatory elements.

The effect of several transcriptional regulatory elements on gene expression in mammalian cells was investigated. As a reporter gene we have used the bacterial gene merA coding for the enzyme mercuric reductase. Several plasmids were constructed with different promoter/enhancer sequences (pSV/E, pSV/L, pMT, pRSV or pAd) at the 5' end and different splicing (small intron of the T antigen of SV40 or the second intron of the rabbit beta-globin gene) and/or polyadenylation signals (AEn, ALn or AR beta Gn) at the 3' end of the merA gene. Expression was measured in five different mammalian cell lines. In COS cells the highest level of expression is obtained with pSV/L and the lowest level with pSV/E. In HeLa, CV-1, Ltk-, and CHO cells merA expression is relatively high, under control of pRSV and pMT and relatively low under control of pSV/L and pAd. The introns studied have a negative effect on the expression of merA. The presence of a polyadenylation signal downstream from the gene is essential for its expression. The three different polyadenylation signals studied give a similar stimulatory effect on the level of expression of the merA gene.

Animals↗
PubMed1991

Transient expression of deletion mutants of the herpes simplex virus thymidine kinase-encoding gene in mouse fibroblast cells.

Previous studies have shown that at least three polypeptides of 43, 39 and 38 kDa are translated from separate AUG codons of the thymidine kinase (TK) encoding mRNA of herpes simplex virus type 1. In addition, small tk-specific transcripts initiated within the tk coding region were observed. However, functional activity of these three proteins and their role in establishing of the TK+ cell phenotype is not yet clear. In order to locate the 5' boundary of the gene encoding functionally active TK, we constructed a set of deletion mutants with truncated 5' ends and examined their ability to provide a TK+ phenotype after microinjection into nuclei of LTK- cells. The results demonstrate that nucleotide sequences upstream from the second ATG codon can be removed without affecting the TK+ phenotype. Deletion of the second start codon and its downstream region inactivates the TK function. Those deletion mutants which contain only the third ATG codon are TK-. Thus, the 38-kDa polypeptide that initiates at the third start codon is not endowed with the TK+ activity. Constructs containing deletions up to nt +210 and lacking all 5'-end canonical and aberrant transcription control regions, as well as first start codon, can provide the TK+ function.

Animals↗
PubMed1995

Cloning and transient expression of genes encoding the human alpha 4 and beta 2 neuronal nicotinic acetylcholine receptor (nAChR) subunits.

Partial cDNA clones generated by RT-PCR were used as probes to clone the cDNAs encoding the human alpha 4 and beta 2 neuronal nicotinic acetylcholine receptor (nAChR) subunits. The 2.1-kb alpha 4 cDNA shows 84 and 76% identity to the rat and chicken cDNA sequences, respectively. The deduced amino-acid sequence shares 89 and 84% similarity, respectively, with the corresponding rat and chicken proteins, with most of the divergence occurring in the cytoplasmic domain. The 1721-nucleotide beta 2 sequence was identical to the human beta 2 sequence previously reported. Transfection of the alpha 4 and beta 2 clones into HEK293 cells resulted in the formation of binding sites that display high affinity towards [3H] cytisine, a characteristic of the alpha 4 beta 2 subtype produced in vivo.

Amino Acid Sequence↗