Contrasted Reactivity to Oxygen Tensions inFrankiasp. Strain CcI3 throughout Nitrogen Fixation and Assimilation

Reconciling the irreconcilable is a primary struggle in aerobic nitrogen-fixing bacteria. Although nitrogenase is oxygen and reactive oxygen species-labile, oxygen tension is required to sustain respiration. In the nitrogen-fixingFrankia, various strategies have been developed through evolution to control the respiration and nitrogen-fixation balance. Here, we assessed the effect of different oxygen tensions onFrankiasp. strain CcI3 growth, vesicle production, and gene expression under different oxygen tensions. Both biomass and vesicle production were correlated with elevated oxygen levels under both nitrogen-replete and nitrogen-deficient conditions. The mRNA levels for the nitrogenase structural genes (nifHDK) were high under hypoxic and hyperoxic conditions compared to oxic conditions. The mRNA level for the hopanoid biosynthesis genes (sqhC andhpnC) was also elevated under hyperoxic conditions suggesting an increase in the vesicle envelope. Under nitrogen-deficient conditions, thehup2 mRNA levels increased with hyperoxic environment, whilehup1 mRNA levels remained relatively constant. Taken together, these results indicate thatFrankiaprotects nitrogenase by the use of multiple mechanisms including the vesicle-hopanoid barrier and increased respiratory protection.

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Differential Gene Expression of Steroid 5α-Reductase 2 in Core Needle Biopsies from Malignant and Benign Prostatic Tissue1

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.82.7.4080 ◽

1997 ◽

Vol 82 (7) ◽

pp. 2210-2214

Author(s):

Catarina Bjelfman ◽

Torbjörn G. Söderström ◽

Einar Brekkan ◽

Bo Johan Norlén ◽

Lars Egevad ◽

...

Keyword(s):

Gene Expression ◽

Messenger Rna ◽

Mrna Level ◽

Transrectal Ultrasound ◽

Mrna Levels ◽

Prostate Hyperplasia ◽

Noncancerous Tissue ◽

Core Needle ◽

Total Rna ◽

Prostate Diseases

Androgens are implicated in the development of prostate cancer (CAP) and benign prostate hyperplasia. The conversion of testosterone to the more potent metabolite dihydrotestosterone by prostate-specific steroid 5α-reductase type 2 (5α-red2) is a key mechanism in the action of androgens in the prostate and is important in the promotion and progression of prostate diseases. Manipulation of the turnover of androgens is thus fundamental in the pharmacological treatment strategy. We have developed a sensitive solution hybridization method for quantification of the gene expression of 5α-red2 in core needle biopsies of the prostate. The 5α-red2-specific messenger RNA (mRNA) levels were measured in 50 human prostate transrectal ultrasound-guided core biopsies obtained from 31 outpatients (median age 72, range 57–88 yr) undergoing biopsy for diagnostic purposes. Significant differences were observed in the gene expression of 5α-red2 between cancerous and noncancerous tissue. In the 14 biopsies judged cancerous, the median 5α-red mRNA levels were 3.5 amol/ng total RNA compared with 12.0 amol/ng total RNA in the biopsies showing no cancer (P = 0.0018). The median 5α-red2 mRNA level in noncancerous tissue was thus 3.4 times higher than in the cancerous specimens.

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Developmental expression of pIgR gene in sheep mammary gland and hormonal regulation

Journal of Dairy Research ◽

10.1017/s0022029901005362 ◽

2002 ◽

Vol 69 (1) ◽

pp. 13-26 ◽

Cited By ~ 22

Author(s):

AURORE RINCHEV-ALARNOLD ◽

LUCETTE BELAIR ◽

JEAN DJIANE

Keyword(s):

Gene Expression ◽

Mammary Gland ◽

Hormonal Regulation ◽

Mrna Level ◽

Immunohistochemical Analysis ◽

Developmental Expression ◽

Secretory Iga ◽

Mrna Levels ◽

Immunoglobulin Receptor ◽

Pregnancy And Lactation

Secretory IgA found in external secretions are constituted by polymeric IgA (pIgA) bound to the extra-cellular part of the polymeric immunoglobulin receptor (pIgR). The receptor mediates transcytosis of pIgA across epithelial cells. The aim of the present study was to analyse the evolution of pIgR expression in the sheep mammary gland during the development of the mammary gland and to analyse its hormonal regulation. Gene expression of the pIgR was analysed in sheep mammary gland during pregnancy and lactation. By Northern Blot analysis, we observed that low levels of pIgR mRNA are expressed until day 70 of pregnancy. Accumulation of pIgR mRNA started during the third part of pregnancy and intensified 3 d after parturition to reach highest levels during established lactation (day 70). In situ hybridization analysis was used to confirm the increase in pIgR gene expression per mammary epithelial cell. In order to examine the hormonal regulation of the pIgR expression, virgin ewes were hormonally treated. Treatment with oestradiol and progesterone increased pIgR mRNA levels slightly. Subsequent addition of glucocorticoids induced a significant accumulation of pIgR mRNA in the mammary gland of the treated animals. Immunohistochemical analysis was performed to verify that the increase of pIgR mRNA level was associated with enhancement of the pIgR protein in mammary cells. No increase of pIgR mRNA levels were observed if PRL secretion was blocked by bromocryptine injections throughout the hormonal procedure. In conclusion, the present experiments suggest that the enhancement of pIgR levels during lactation result from combined effects of both prolactin and glucocorticoids.

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Differential regulation of γ-glutamylcysteine synthetase heavy and light subunit gene expression

Biochemical Journal ◽

10.1042/bj3260167 ◽

1997 ◽

Vol 326 (1) ◽

pp. 167-172 ◽

Cited By ~ 82

Author(s):

Jiaxin CAI ◽

Zong-Zhi HUANG ◽

Shelly C. LU

Keyword(s):

Oxidative Stress ◽

Gene Expression ◽

Steady State ◽

Mrna Level ◽

Rat Hepatocytes ◽

Mrna Levels ◽

Subunit Gene ◽

Subunit Mrna ◽

Glutamylcysteine Synthetase ◽

Steady State Mrna Level

γ-Glutamylcysteine synthetase (GCS) is the rate-limiting enzyme in the biosynthesis of glutathione and is composed of a heavy and a light subunit. Although the heavy subunit is enzymically active alone, the light subunit plays an important regulatory role by making the holoenzyme function more efficiently. In the current study we examined whether conditions which are known to influence gene expression of the heavy subunit also influence that of the light subunit, and the mechanisms involved. Treatment of cultured rat hepatocytes with hormones such as insulin and hydrocortisone, or plating hepatocytes under low cell density increased the steady-state mRNA level of the heavy subunit only. Treatment with diethyl maleate (DEM), buthionine sulphoximine (BSO) and t-butylhydroquinone (TBH) increased the steady state mRNA level and gene transcription rates of both subunits. These treatments share in common their ability to induce oxidative stress and activate nuclear factor κB (NF-κB). Treatment with protease inhibitors 7-amino-1-chloro-3-tosylamido-2-heptanone (TLCK) or L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK) had no influence on the basal NF-κB and GCS subunit mRNA levels, but blocked the activation of NF-κB by DEM, BSO and TBH, and the increase in GCS heavy subunit mRNA level by BSO and TBH. On the other hand, the DEM-, BSO- and TBH-induced increase in GCS light-subunit mRNA level was unaffected by TLCK and TPCK. Thus only the heavy subunit is hormonally regulated and growth sensitive, whereas both subunits are regulated by oxidative stress. Signalling through NF-κB is involved only in the oxidative-stress-mediated changes in the heavy subunit gene expression.

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Treatment with PPARαAgonist Clofibrate Inhibits the Transcription and Activation of SREBPs and Reduces Triglyceride and Cholesterol Levels in Liver of Broiler Chickens

PPAR Research ◽

10.1155/2015/347245 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 6

Author(s):

Lijun Zhang ◽

Chunyan Li ◽

Fang Wang ◽

Shenghua Zhou ◽

Mingjun Shangguan ◽

...

Keyword(s):

Gene Expression ◽

Broiler Chickens ◽

Target Genes ◽

Nuclear Protein ◽

Mrna Level ◽

Control Group ◽

Mrna Levels ◽

Protein Levels ◽

Cholesterol Levels ◽

Regulation Mechanisms

PPARαagonist clofibrate reduces cholesterol and fatty acid concentrations in rodent liver by an inhibition of SREBP-dependent gene expression. In present study we investigated the regulation mechanisms of the triglyceride- and cholesterol-lowering effect of the PPARαagonist clofibrate in broiler chickens. We observed that PPARαagonist clofibrate decreases the mRNA and protein levels of LXRαand the mRNA and both precursor and nuclear protein levels of SREBP1 and SREBP2 as well as the mRNA levels of the SREBP1 (FASNandGPAM) and SREBP2 (HMGCRandLDLR) target genes in the liver of treated broiler chickens compared to control group, whereas the mRNA level ofINSIG2, which inhibits SREBP activation, was increased in the liver of treated broiler chickens compared to control group. Taken together, the effects of PPARαagonist clofibrate on lipid metabolism in liver of broiler chickens involve inhibiting transcription and activation of SREBPs and SREBP-dependent lipogenic and cholesterologenic gene expression, thereby resulting in a reduction of the triglyceride and cholesterol levels in liver of broiler chickens.

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Transcriptional Activities of the Microbial Consortium Living with the Marine Nitrogen-Fixing Cyanobacterium Trichodesmium Reveal Potential Roles in Community-Level Nitrogen Cycling

Applied and Environmental Microbiology ◽

10.1128/aem.02026-17 ◽

2017 ◽

Vol 84 (1) ◽

Cited By ~ 6

Author(s):

Michael D. Lee ◽

Eric A. Webb ◽

Nathan G. Walworth ◽

Fei-Xue Fu ◽

Noelle A. Held ◽

...

Keyword(s):

Gene Expression ◽

Nitrogen Fixation ◽

Microbial Communities ◽

Nitrogen Cycling ◽

Carbon Fixation ◽

Community Respiration ◽

Ecological Niches ◽

Nitrogen Fixing ◽

Content Type ◽

Globally Distributed

ABSTRACTTrichodesmiumis a globally distributed cyanobacterium whose nitrogen-fixing capability fuels primary production in warm oligotrophic oceans. Like many photoautotrophs,Trichodesmiumserves as a host to various other microorganisms, yet little is known about how this associated community modulates fluxes of environmentally relevant chemical species into and out of the supraorganismal structure. Here, we utilized metatranscriptomics to examine gene expression activities of microbial communities associated withTrichodesmium erythraeum(strain IMS101) using laboratory-maintained enrichment cultures that have previously been shown to harbor microbial communities similar to those of natural populations. In enrichments maintained under two distinct CO2concentrations for ∼8 years, the community transcriptional profiles were found to be specific to the treatment, demonstrating a restructuring of overall gene expression had occurred. Some of this restructuring involved significant increases in community respiration-related transcripts under elevated CO2, potentially facilitating the corresponding measured increases in host nitrogen fixation rates. Particularly of note, in both treatments, community transcripts involved in the reduction of nitrate, nitrite, and nitrous oxide were detected, suggesting the associated organisms may play a role in colony-level nitrogen cycling. Lastly, a taxon-specific analysis revealed distinct ecological niches of consistently cooccurring major taxa that may enable, or even encourage, the stable cohabitation of a diverse community withinTrichodesmiumconsortia.IMPORTANCETrichodesmiumis a genus of globally distributed, nitrogen-fixing marine cyanobacteria. As a source of new nitrogen in otherwise nitrogen-deficient systems, these organisms help fuel carbon fixation carried out by other more abundant photoautotrophs and thereby have significant roles in global nitrogen and carbon cycling. Members of theTrichodesmiumgenus tend to form large macroscopic colonies that appear to perpetually host an association of diverse interacting microbes distinct from the surrounding seawater, potentially making the entire assemblage a unique miniature ecosystem. Since its first successful cultivation in the early 1990s, there have been questions about the potential interdependencies betweenTrichodesmiumand its associated microbial community and whether the host's seemingly enigmatic nitrogen fixation schema somehow involved or benefited from its epibionts. Here, we revisit these old questions with new technology and investigate gene expression activities of microbial communities living in association withTrichodesmium.

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Regulation of pituitary inhibin/activin subunits and follistatin gene expression by GnRH in female rats

Journal of Endocrinology ◽

10.1530/joe-10-0485 ◽

2011 ◽

Vol 210 (1) ◽

pp. 71-79 ◽

Cited By ~ 7

Author(s):

Petra Popovics ◽

Zoltan Rekasi ◽

Alan J Stewart ◽

Magdolna Kovacs

Keyword(s):

Gene Expression ◽

Mrna Level ◽

Inhibin B ◽

Female Rats ◽

Pituitary Cells ◽

Mrna Levels ◽

Short Term ◽

Α Subunit ◽

Long Term Treatment

Pituitary inhibin B, activin B, and follistatin are local regulators of FSH. Activin B is a homodimeric molecule (βB–βB), while inhibin B contains an α and a βB subunit. The regulation of gene expression of α, βB, and follistatin by local and endocrine hormones was examined in pituitaries from female rats and in perifused pituitary cells by RT-PCR. Ovariectomy (OVX) induced an elevation in the mRNA level of α and βB subunits and follistatin. Short-term (4 h) treatment of pituitary cells with GnRH decreased both the inhibin α and the inhibin/activin βB subunit mRNA levels, while long-term treatment (20 h) with 100 nM GnRH stimulated the expression of both subunits. In contrast, the mRNA level of follistatin was elevated after the short-term GnRH treatment. Long-term exposure of pituitary cells to estradiol and inhibin B suppressed the mRNA expression of βB and had no effect on the expression of α subunit and follistatin. Our results demonstrate that the increased expressions of inhibin/activin subunits and follistatin in the post-OVX period can be induced by the lack of gonadal negative feedback, resulting in a high GnRH environment in the pituitary. This study reports for the first time that GnRH administered in high doses and for a long period stimulates the gene expression of inhibin/activin subunits and thereby may contribute to the stimulatory effect of OVX on the expression of these genes.

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Modulation of cytokeratin and actin gene expression and fibrillar organization in cultured rat hepatocytes

Biochemistry and Cell Biology ◽

10.1139/o92-170 ◽

1992 ◽

Vol 70 (10-11) ◽

pp. 1238-1248 ◽

Cited By ~ 5

Author(s):

Normand Marceau ◽

Andrée Grenier ◽

Micheline Noel ◽

Donald Mailhot ◽

Anne Loranger

Keyword(s):

Gene Expression ◽

Dimethyl Sulfoxide ◽

Intermediate Filaments ◽

Mrna Level ◽

Rat Hepatocytes ◽

Culture Conditions ◽

Actin Gene ◽

Mrna Levels ◽

Cultured Rat Hepatocytes ◽

Hepatocyte Spheroids

Intermediate filaments of rat hepatocytes are composed of cytokeratins 8 and 18 (CK8 and CK18, respectively). Recent work from our laboratory has indicated a close relationship between the synthesis of these cytokeratins, their organization into intermediate filaments, and the promotion of growth and differentiation of cultured rat hepatocytes by insulin, epidermal growth factor, and dexamethasone. In the present study, we examined the mRNA expression, level of protein synthesis, and fibrillar distribution of cytokeratins 8 and 18 and actin in hepatocytes, isolated from normal and dexamethasone-injected rats and cultured as monolayers or spheroids in the presence of insulin, or from normal rat hepatocytes, cultured as monolayers in the presence of dexamethasone, insulin, and dimethyl sulfoxide. The CK8 mRNA level was lower in hepatocytes isolated from noninjected rats and cultured as either monolayers or spheroids, than in those from dexamethasone-injected rats. However, the CK18 mRNA level varied in a manner that was different from that of CK8 mRNA, showing that the modes of expression of the two genes were independent. The various changes in hepatocyte culture conditions led to variations in albumin mRNA levels that largely followed those observed in CK8 mRNA levels. In the case of actin, the amount of mRNAs varied from relatively high levels in hepatocyte monolayers to extremely low levels in hepatocyte spheroids, even though in both cases the cells were isolated from dexamethasone-injected rats. These changes in mRNA levels did not necessarily correlate with changes in the synthesis of cytokeratins 8 and 18, and actin. Changes in culture conditions induced a major reorganization in the distribution of cytokeratin intermediate filaments and actin filament between the region near the surface membrane and the cytoplasm. The most divergent patterns in cytokeratin intermediate filaments and actin filament distributions were observed between hepatocytes cultured as spheroidal aggregates and as monolayers in the presence of dimethyl sulfoxide. The former condition resulted in patterns of cytokeratin and actin gene expression and fibrillar organization that best matched those in situ. In the latter condition, inappropriate patterns were obtained, in spite of the fact that dimethyl sulfoxide treated hepatocytes are known to exhibit survival and functional activities equivalent to that of hepatocyte spheroids. These results demonstrate for the first time that the survival and functional activity (i.e., albumin production) of rat hepatocytes in vitro is not necessarily correlated with a particular pattern of cytokeratin and actin gene expression and fibrillar arrangement.Key words: gene expression, cytokeratins, intermediate filaments, cytoskeleton, hepatocytes.

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Tight Control of Respiration by NADH Dehydrogenase ND5 Subunit Gene Expression in Mouse Mitochondria

Molecular and Cellular Biology ◽

10.1128/mcb.20.3.805-815.2000 ◽

2000 ◽

Vol 20 (3) ◽

pp. 805-815 ◽

Cited By ~ 90

Author(s):

Yidong Bai ◽

Rebecca M. Shakeley ◽

Giuseppe Attardi

Keyword(s):

Gene Expression ◽

Nadh Dehydrogenase ◽

Mrna Level ◽

Mouse Cell ◽

Synthesis Rate ◽

Mrna Levels ◽

Wild Type ◽

Normal Number ◽

Nd5 Gene ◽

Cell Variant

ABSTRACT A mouse cell variant carrying in heteroplasmic form a nonsense mutation in the mitochondrial DNA-encoded ND5 subunit of the respiratory NADH dehydrogenase has been isolated and characterized. The derivation from this mutant of a large number of cell lines containing between 4 and 100% of the normal number of wild-type ND5 genes has allowed an analysis of the genetic and functional thresholds operating in mouse mitochondria. In wild-type cells, ∼40% of the ND5 mRNA level was in excess of that required for ND5 subunit synthesis. However, in heteroplasmic cells, the functional mRNA level decreased in proportion to the number of wild-type ND5 genes over a 25-fold range, pointing to the lack of any compensatory increase in rate of transcription and/or stability of mRNA. Most strikingly, the highest ND5 synthesis rate was just sufficient to support the maximum NADH dehydrogenase-dependent respiration rate, with no upregulation of translation occurring with decreasing wild-type mRNA levels. These results indicate that, despite the large excess of genetic potential of the mammalian mitochondrial genome, respiration is tightly regulated by ND5 gene expression.

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Transcript of protein kinase A knock-down modulates feeding behavior and neuropeptide Y gene expression in phenylpropanolamine-treated rats

Physiological Genomics ◽

10.1152/physiolgenomics.00110.2007 ◽

2007 ◽

Vol 31 (2) ◽

pp. 306-314 ◽

Cited By ~ 8

Author(s):

Yih-Shou Hsieh ◽

Shun-Fa Yang ◽

Shu-Chen Chu ◽

Dong-Yih Kuo

Keyword(s):

Gene Expression ◽

Protein Kinase ◽

Neuropeptide Y ◽

Protein Kinase A ◽

Mrna Level ◽

Camp Response Element Binding ◽

Antisense Oligodeoxynucleotide ◽

Mrna Levels ◽

Knock Down ◽

Kinase A

Neuropeptide Y (NPY) is an appetite-controlling neuromodulator that contributes to the appetite-suppressing effect of phenylpropanolamine (PPA). Aims of this study were to investigate whether protein kinase A (PKA) signaling is involved in regulating NPY gene expression and PPA-induced anorexia. Rats were given daily with PPA for 5 days. Changes in daily food intake and hypothalamic NPY, PKA, cAMP response element binding protein (CREB), and pro-opiomelanocortin (POMC) gene expression were measured and compared. To further determine if PKA was involved, intracerebroventricular infusions of antisense oligodeoxynucleotide were performed at 60 min before daily PPA treatment in freely moving rats. Results showed that daily PKA, CREB, and POMC expression were increased following PPA treatment, which showed a closely reverse relationship with alterations of decreased feeding behaviors and NPY mRNA levels. Results also showed that PKA knock-down could block PPA-induced anorexia as well as restore NPY mRNA level, indicating the involvement of PKA signaling in the regulation of NPY gene expression. It is suggested that hypothalamic PKA signaling may participate in the central regulation of PPA-mediated appetite suppression via the modulation of hypothalamic NPY gene expression. The present findings reveal that manipulations at the molecular level of PKA or cAMP may allow the development of therapeutic agents to improve the undesirable properties of PPA or other amphetamine-like anorectic drugs.

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Gene expression of the three members of hepatocyte nuclear factor-3 is differentially regulated by nutritional and hormonal factors

Journal of Endocrinology ◽

10.1677/joe.0.167r001 ◽

2000 ◽

Vol 167 (1) ◽

pp. R1-R5 ◽

Cited By ~ 14

Author(s):

M Imae ◽

Y Inoue ◽

Z Fu ◽

H Kato ◽

T Noguchi

Keyword(s):

Gene Expression ◽

Mrna Level ◽

Regulation Of Gene Expression ◽

Diabetic Rats ◽

Physiological Status ◽

Mrna Levels ◽

Dependent Manner ◽

Nuclear Factor ◽

Hepatocyte Nuclear Factor ◽

Protein Free Diet

Hepatocyte nuclear factor-3 (HNF-3) belongs to a large family of forkhead transcription factors and is made up of three members (HNF-3alpha, -3beta and -3gamma). It has been shown that HNF-3 regulates a number of metabolically important genes. However, the mechanisms underlying this regulation of HNF-3 activity by hormones and nutrition have not yet been well elucidated. In attempting to explore the regulation of gene expression of HNF-3 members by physiological status, we analyzed the effects of insulin, dexamethasone and protein malnutrition on the hepatic mRNA level of each member. Male Wistar rats were fed on a 12% casein diet, 12% gluten diet (deficient in lysine and threonine) or a protein-free diet for 1 week. The protein-free diet and gluten diet caused a 3. 7-fold increase in HNF-3g mRNA in the liver and did not affect the mRNA level of either HNF-3alpha or HNF-3beta. Daily administration of dexamethasone caused the mRNA levels of HNF-3alpha and HNF-3beta to increase (2.3- and 1.4-fold, respectively), but had no effect on the HNF-3gamma mRNA level. In diabetic rats that had been injected with streptozotocin, an elevation of the hepatic mRNA levels of HNF-3beta and HNF-3gamma was observed (1.6-and 1.9-fold, respectively). Insulin replacement in the diabetic rats decreased both mRNA levels in a dose-dependent manner. HNF-3alpha mRNA was not affected by insulin status. These results show that the genes of the three members of the HNF-3 family respond differently to hormonal and nutritional factors suggesting that the activities of HNF-3 members are regulated, at least in part, by the levels of their gene expression.

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