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Biomedical subjects

E D Jarvis

Publications and source records attributed to E D Jarvis.

At least 19 recordsLinked to original sources
PubMed2000

A membrane-associated progesterone-binding protein, 25-Dx, is regulated by progesterone in brain regions involved in female reproductive behaviors.

The ventromedial hypothalamus (VMH) plays a central role in the regulation of the female reproductive behavior lordosis, a behavior dependent upon the sequential activation of receptors for the ovarian steroid hormones estradiol (E) and progesterone (P). These receptors function as transcription factors to alter the expression of target genes. To discover behaviorally relevant genes targeted by E and P in the VMH, we used the differential display PCR to identify messenger RNAs that are differentially expressed in the hypothalamus of ovariectomized (ovx) rats treated with E alone compared with ovariectomized rats treated with E and P. We show here that one interesting mRNA within the hypothalamus that is repressed by P after E priming encodes the protein 25-Dx, the rat homolog of the human membrane-associated P-binding protein Hpr6.6. Neurons in the brain containing the highest levels of 25-Dx are located in several nuclei of the basal forebrain, including the VMH. 25-Dx expression is also higher in the hypothalamus of female P receptor "knockout" mice than in their wild-type littermates. These findings suggest a mechanism in which the activation of nuclear P receptor represses expression of a membrane P receptor, 25-Dx, during lordosis facilitation.

Animals↗
PubMed2000

Behaviourally driven gene expression reveals song nuclei in hummingbird brain.

Hummingbirds have developed a wealth of intriguing features, such as backwards flight, ultraviolet vision, extremely high metabolic rates, nocturnal hibernation, high brain-to-body size ratio and a remarkable species-specific diversity of vocalizations. Like humans, they have also developed the rare trait of vocal learning, this being the ability to acquire vocalizations through imitation rather than instinct. Here we show, using behaviourally driven gene expression in freely ranging tropical animals, that the forebrain of hummingbirds contains seven discrete structures that are active during singing, providing the first anatomical and functional demonstration of vocal nuclei in hummingbirds. These structures are strikingly similar to seven forebrain regions that are involved in vocal learning and production in songbirds and parrots--the only other avian orders known to be vocal learners. This similarity is surprising, as songbirds, parrots and hummingbirds are thought to have evolved vocal learning and associated brain structures independently, and it indicates that strong constraints may influence the evolution of forebrain vocal nuclei.

Animals↗
PubMed2000

A relationship between behavior, neurotrophin expression, and new neuron survival.

The high vocal center (HVC) controls song production in songbirds and sends a projection to the robust nucleus of the archistriatum (RA) of the descending vocal pathway. HVC receives new neurons in adulthood. Most of the new neurons project to RA and replace other neurons of the same kind. We show here that singing enhances mRNA and protein expression of brain-derived neurotrophic factor (BDNF) in the HVC of adult male canaries, Serinus canaria. The increased BDNF expression is proportional to the number of songs produced per unit time. Singing-induced BDNF expression in HVC occurs mainly in the RA-projecting neurons. Neuronal survival was compared among birds that did or did not sing during days 31-38 after BrdUrd injection. Survival of new HVC neurons is greater in the singing birds than in the nonsinging birds. A positive causal link between pathway use, neurotrophin expression, and new neuron survival may be common among systems that recruit new neurons in adulthood.

Animals↗
PubMed2000

Molecular mapping of brain areas involved in parrot vocal communication.

Auditory and vocal regulation of gene expression occurs in separate discrete regions of the songbird brain. Here we demonstrate that regulated gene expression also occurs during vocal communication in a parrot, belonging to an order whose ability to learn vocalizations is thought to have evolved independently of songbirds. Adult male budgerigars (Melopsittacus undulatus) were stimulated to vocalize with playbacks of conspecific vocalizations (warbles), and their brains were analyzed for expression of the transcriptional regulator ZENK. The results showed that there was distinct separation of brain areas that had hearing- or vocalizing-induced ZENK expression. Hearing warbles resulted in ZENK induction in large parts of the caudal medial forebrain and in 1 midbrain region, with a pattern highly reminiscent of that observed in songbirds. Vocalizing resulted in ZENK induction in nine brain structures, seven restricted to the lateral and anterior telencephalon, one in the thalamus, and one in the midbrain, with a pattern partially reminiscent of that observed in songbirds. Five of the telencephalic structures had been previously described as part of the budgerigar vocal control pathway. However, functional boundaries defined by the gene expression patterns for some of these structures were much larger and different in shape than previously reported anatomical boundaries. Our results provide the first functional demonstration of brain areas involved in vocalizing and auditory processing of conspecific sounds in budgerigars. They also indicate that, whether or not vocal learning evolved independently, some of the gene regulatory mechanisms that accompany learned vocal communication are similar in songbirds and parrots.

Animals↗
PubMed1999

The 70-kDa heat shock cognate protein (Hsc73) gene is enhanced by ovarian hormones in the ventromedial hypothalamus.

Estrogen (E) and progesterone (P) orchestrate many cellular responses involved in female reproductive physiology, including reproductive behaviors. E- and P-binding neurons important for lordosis behavior have been located within the ventromedial hypothalamus (VMH), and several hormone-responsive genes have been observed there as well. In attempts to identify additional E- and P-responsive genes in the VMH that may contribute to sexual behaviors, we used the differential display mRNA screening technique. One of the genes identified encodes the 73-kDa heat shock cognate protein (Hsc73). Quantitative in situ hybridization analysis of brains from naturally cycling female rats revealed a significant increase in Hsc73 mRNA in the VMH and arcuate nucleus of animals during proestrus compared with those at diestrus-1. To confirm that these increases were steroid hormone dependent, we compared vehicle-treated ovariectomized females with ovariectomized females treated with estradiol benzoate and P. Northern analysis and in situ hybridizations showed that the Hsc73 gene is enhanced by E and P in the pituitary and subregions of the VMH. Incidentally, by examining the primary amino acid sequence of rat, human, and chicken progesterone receptors, we noticed that putative Hsc73 binding sites are conserved across species with similar sites existing in the androgen and glucocorticoid receptors. Together these findings suggest a possible mechanism through which E could influence the activities of progesterone, androgen, and glucocorticoid receptors, by enhancing the expression of Hsc73 in cells where these proteins colocalize.

Amino Acid Sequence↗
PubMed1998

For whom the bird sings: context-dependent gene expression.

Male zebra finches display two song behaviors: directed and undirected singing. The two differ little in the vocalizations produced but greatly in how song is delivered. "Directed" song is usually accompanied by a courtship dance and is addressed almost exclusively to females. "Undirected" song is not accompanied by the dance and is produced when the male is in the presence of other males, alone, or outside a nest occupied by its mate. Here, we show that the anterior forebrain vocal pathway contains medial and lateral "cortical-basal ganglia" subdivisions that have differential ZENK gene activation depending on whether the bird sings female-directed or undirected song. Differences also occur in the vocal output nucleus, RA. Thus, although these two vocal behaviors are very similar, their brain activation patterns are dramatically different.

Animals↗
PubMed1998

Classification and genetic characterization of pattern-forming Bacilli.

One of the more natural but less commonly studied forms of colonial bacterial growth is pattern formation. This type of growth is characterized by bacterial populations behaving in an organized manner to generate readily identifiable geometric and predictable morphologies on solid and semi-solid surfaces. In our first attempt to study the molecular basis of pattern formation in Bacillus subtilis, we stumbled upon an enigma: some strains used to describe pattern formation in B. subtilis did not have the phenotypic or genotypic characteristics of B. subtilis. In this report, we show that these strains are actually not B. subtilis, but belong to a different class of Bacilli, group I. We show further that commonly used laboratory strains of B. subtilis can co-exist as mixed cultures with group I Bacilli, and that the latter go unnoticed when grown on frequently used laboratory substrates. However, when B. subtilis is grown under more stringent semiarid conditions, members of group I emerge in the form of complex patterns. When B. subtilis is grown under less stringent and more motile conditions, B. subtilis forms its own pattern, and members of group I remain unnoticed. These findings have led us to revise some of the mechanistic and evolutionary hypotheses that have been proposed to explain pattern growth in Bacilli.

Bacillus↗
PubMed1997

Selective expression of insulin-like growth factor II in the songbird brain.

Neuronal replacement occurs in the forebrain of juvenile and adult songbirds. To address the molecular processes that govern this replacement, we cloned the zebra finch insulin-like growth factor II (IGF-II) cDNA, a factor known to regulate neuronal development and survival in other systems, and examined its expression pattern by in situ hybridization and immunocytochemistry in juvenile and adult songbird brains. The highest levels of IGF-II mRNA expression occurred in three nuclei of the song system: in the high vocal center (HVC), in the medial magnocellular nucleus of the neostriatum (mMAN), which projects to HVC, and to a lesser extent in the robust nucleus of the archistriatum (RA), which receives projections from HVC. IGF-II mRNA expression was developmentally regulated in zebra finches. In canary HVC, monthly changes in IGF-II mRNA expression covaried with previously reported monthly differences in neuron incorporation. Combining retrograde tracers with in situ hybridization and immunocytochemistry, we determined that the HVC neurons that project to area X synthesize the IGF-II mRNA, whereas the adjacent RA-projecting neurons accumulate the IGF-II peptide. Our findings raise the possibility that within HVC IGF-II acts as a paracrine signal between nonreplaceable area X-projecting neurons and replaceable RA-projecting neurons, a mode of action that is compatible with the involvement of IGF-II with the replacement of neurons. Additional roles for IGF-II expression in songbird brain are likely, because expression also occurs in some brain areas outside the song system, among them the cerebellar Purkinje cells in which neurogenesis is not known to occur.

Amino Acid Sequence↗
PubMed1997

Brain gene regulation by territorial singing behavior in freely ranging songbirds.

To investigate the ecological relevance of brain gene regulation associated with singing behavior in songbirds, we challenged freely ranging song sparrows with conspecific song playbacks within their breeding territories. Males responded by approaching the speaker, searching for an intruder and actively singing. In situ hybridization of brain sections revealed significantly higher expression of the transcriptional regulator ZENK in challenged birds than in unstimulated controls in several auditory structures and song control nuclei. We conclude that singing behavior in the context of territorial defense is associated with gene regulation in brain centers that control song perception and production, and that behaviorally regulated gene expression can be used to investigate brain areas involved in the natural behaviors of freely ranging animals.

Animals↗
PubMed1997

Motor-driven gene expression.

There is increased neuronal firing in the high vocal center (a motor nucleus) and other song nuclei of canaries, Serinus canaria, and zebra finches, Taeniopygia guttata, whenever these songbirds sing or hear song. These observations suggested that song perception involved sensory and motor pathways. We now show that the act of singing, but not hearing song, induces a rapid and striking increase (up to 60-fold) in expression of the transcriptional regulator ZENK in the high vocal center and other song nuclei. This motor-driven gene expression is independent of auditory feedback, since it occurs in deafened birds when they sing and in muted birds when they produce silent song. Conversely, hearing song, but not the act of singing, induces ZENK expression in parts of the auditory forebrain. Our observations show that even though the same auditory stimulus activates sensory and motor pathways, perception and production of song are accompanied by anatomically distinct patterns of gene expression.

Animals↗
PubMed1997

Identification of aberrantly regulated genes in diseased skin using the cDNA differential display technique.

It is hypothesized that psoriasis may be caused by aberrant gene expression. In an effort to identify and clone psoriasis-specific genes, we compared gene expression in normal, tape-stripped (wounded), and psoriatic skin using the cDNA differential display technique. Four genes not previously described in psoriasis--connexin 26, a gap junction protein; squamous cell carcinoma antigen-1 (SCCA1), a serine protease inhibitor; and mitochondrial NAD subunits 5 and 6--were identified as having very high expression levels in psoriatic skin. In situ hybridizations showed that connexin 26 mRNA was expressed 10-fold higher in psoriatic and 4-fold higher in tape-stripped epidermis than in controls. SCCA1 showed a 40-fold increase in mRNA expression, whereas mitochondrial NAD5 and NAD6 expression was increased 10- and 20-fold, respectively, in psoriatic skin. Northern blots confirmed the increased expression of connexin 26, SCCA1, and NAD6 genes in psoriatic skin. Immunohistochemistry showed that connexin 26 protein was strongly expressed in spinous keratinocytes from psoriatic skin and chronic wounds, but was absent in normal epidermis. These studies demonstrate the usefulness of this approach for identifying genes that are conditionally expressed in growth-activated human skin.

Antigens, Neoplasm↗
PubMed1993

Two tRNA gene clusters associated with rRNA operons rrnD and rrnE in Bacillus subtilis.

Sequence analysis of cloned rescued DNA fragments from a Bacillus subtilis strain with an inserted recombinant plasmid in ribosomal operon rrnE revealed the presence of two tRNA genes for Met and Asp at the 3' end of the operon. Probing chromosomal DNA from a strain carrying a plasmid inserted in rrnD with a fragment containing the genetically unassigned cluster of 16 tRNA genes revealed that the cluster is located immediately following the rrnD operon. Our findings show that all 10 rrn operons in B. subtilis are associated with tRNA gene clusters.

Amino Acid Sequence↗
PubMed1990

The structure of the trpE, trpD and 5' trpC genes of Bacillus pumilus.

The nucleotide (nt) sequences of the Bacillus pumilus trpE, trpD and 5' portions of trpC genes have been determined. Genetic analysis suggested the presence of an internal promoter upstream from the trpC gene, yet no typical consensus sequences were found. The nt and amino acid sequence homologies between the B. pumilus, Bacillus subtilis and Escherichia coli trp genes are presented.

Amino Acid Sequence↗
PubMed1990

Genetic structure and DNA sequences at junctions involved in the rearrangements of Bacillus subtilis strains carrying the trpE26 mutation.

Studies on the region upstream to ribosomal operon rrnD of Bacillus subtilis led to the characterization of two of the four chromosomal junctions involved in the rearrangements (a translocation and an inversion) of the strains carrying the trpE26 mutation. Genetic analysis, by integrative mapping, showed linkage of rrnD to cysB and hisA (both on segment A) in the trpE26-type strains. Physical analysis showed that the region upstream to rrnD is now linked to the trpE-ilvA chromosome segment as demonstrated by analyzing restriction site-polymorphism between 168 and trpE26-type strains. Similar experiments confirmed the previous genetic data on linkage in these areas in strains carrying novel rearrangements derived from the trpE26-type strains: stable merodiploids and inversions. The nucleotide sequence of the area 5' to rrnD in both types of strains (168 and trpE26), the region downstream of the citG gene and the region carrying the trpE26 mutation (made available to us by D. Henner) provided evidence for the molecular basis of the differences in structure, allowed the identification of the break points and revealed the presence of a polypurine region upstream to rrnD as seen in other systems in B. subtilis. No extensive homology was found between pairs of junctions so far sequenced. The models proposed by C. Anagnostopoulos for the role of DNA sequences of intrachromosomal homology involved in the transfer of the trpE26 mutation and the formation of novel arrangements require therefore reevaluation.

Amino Acid Sequence↗
PubMed1988

Chromosomal organization of rRNA operons in Bacillus subtilis.

Integrative mapping with vectors containing ribosomal DNA sequences were used to complete the mapping of the 10 rRNA gene sets in the endospore forming bacterium Bacillus subtilis. Southern hybridizations allowed the assignment of nine operons to distinct BclI restriction fragments and their genetic locus identified by transductional crosses. Nine of the ten rRNA gene sets are located between 0 and 70 degrees on the genomic map. In the region surrounding cysA14, two sets of closely spaced tandem clusters are present. The first (rrnJ and rrnW) is located between purA16 and cysA14 closely linked to the latter; the second (rrnI, rrnH and rrnG) previously mapped within this area is located between attSPO2 and glpT6. The operons at or near the origin of replication (rrnO,rrnA and rrnJ,rrnW) represent "hot spots" of plasmid insertion.

Bacillus subtilis↗