MUC1 gene polymorphism in three Nelore lines selected for growth and its association with growth and carcass traits

The objective of this study was to describe the VNTR polymorphism of the mucin 1 gene (MUC1) in three Nelore lines selected for yearling weight to determine whether allele and genotype frequencies of this polymorphism were affected by selection for growth. In addition, the effects of the polymorphism on growth and carcass traits were evaluated. Birth, weaning and yearling weights, rump height, Longissimus muscle area, backfat thickness, and rump fat thickness, were analyzed. A total of 295 Nelore heifers from the Beef Cattle Research Center, Instituto de Zootecnia de Sertozinho, were used, including 41 of the control line, 102 of the selection line and 152 of the traditional. The selection and traditional lines comprise animals selected for higher yearling weight, whereas control line animals are selected for yearling weight close to the average. Five alleles were identified, with allele 1 being the most frequent in the three lines, especially in the lines selected for higher means for yearling weight. Heterozygosity was significantly higher in the control line. Association analyses showed significant effects of allele 1 on birth weight and weaning weight while the allele 3 exert significant effects on yearling weight and back fat thickness. Despite these findings, application of this marker to marker-assisted selection requires more consistent results based on the genotyping of a larger number of animals in order to increase the accuracy of the statistical analyses.

Cytoprotective role of heme oxygenase-1 and heme degradation derived end products in liver injury

The activation of heme oxygenase-1 (HO-1) appears to be an endogenous defensive mechanism used by cells to reduce inflammation and tissue damage in a number of injury models. HO-1, a stress-responsive enzyme that catabolizes heme into carbon monoxide (CO), biliverdin and iron, has previously been shown to protect grafts from ischemia/reperfusion and rejection. In addition, the products of the HO-catalyzed reaction, particularly CO and biliverdin/bilirubin, have been shown to exert protective effects in the liver against a number of stimuli, as in chronic hepatitis C and in transplanted liver grafts. Furthermore, the induction of HO-1 expression can protect the liver against damage caused by a number of chemical compounds. More specifically, the CO derived from HO-1-mediated heme catabolism has been shown to be involved in the regulation of inflammation; furthermore, administration of low concentrations of exogenous CO has a protective effect against inflammation. Both murine and human HO-1 deficiencies have systemic manifestations associated with iron metabolism, such as hepatic overload (with signs of a chronic hepatitis) and iron deficiency anemia (with paradoxical increased levels of ferritin). Hypoxia induces HO-1 expression in multiple rodent, bovine and monkey cell lines, but interestingly, hypoxia represses expression of the human HO-1 gene in a variety of human cell types (endothelial cells, epithelial cells, T cells). These data suggest that HO-1 and CO are promising novel therapeutic molecules for patients with inflammatory diseases. In this review, we present what is currently known regarding the role of HO-1 in liver injuries and in particular, we focus on the implications of targeted induction of HO-1 as a potential therapeutic strategy to protect the liver against chemically induced injury.

Role of caveolin-1 in the proliferation of solid tumours in vitro

Caveolin-1 (Cav-1), the essential structural constituent of caveolae, which are flask-shaped invaginations of the plasma membrane, has been found to play a key role in the modulation of cell proliferation and cancer development. It seems to act as an oncosuppressor or a promoter of growth, depending on the histotype, stage and grade of each tumour. The aim of this study was to analyze the effects of Caveolin-1 gene silencing on the proliferation of human lung cancer and osteosarcoma in vitro. Our data show that Cav-1 silencing blocks the growth in both metastatic lung cancer cell lines analyzed, suggesting a proliferation promoting action of the protein in these cells. A marked decrease of phospho-Akt, phospho-ERK, STAT3, cyclin D1, CDK4 and consequently of phospho-Rb expression was evident in the cells treated with Cav-1 siRNA. With regards to osteosarcoma, we demonstrated that the suppression of Cav-1 results in the blocking of MG-63 and in the slowing down of HOS proliferation, suggesting a role for Cav-1 as a promoter of tumour growth in these cell lines. A marked decrease of phospho-Akt, cyclin E, CDK2 and phospho-Rb and an increase of p21 expression levels were evident in the cells treated with Cav-1 siRNA. Our results suggest two new cell cycle inhibiting pathways, mediated by Cav-1 knock-down, and provide new insights into the molecular mechanisms underlying the tumour-promoting role of Cav-1 in lung cancer and osteosarcoma. In this work we also investigated the role of estrogens in lung cancer and the functional cross-talk between Cav-1 and estrogens/estrogen receptors in it. Our results show that 17β-estradiol induces proliferation either in RAL or in SCLC-R1 cells and that both cell lines are sensitive to 4-OHT antiproliferative effect. The sensitivity to estrogen stimulation seems to be gender- and/or histological type-independent in metastatic lung cancer in vitro.

RNA non-codificanti indotti da danno al DNA regolano il fattore di trascrizione HIF-1α

Recenti analisi sull’intero trascrittoma hanno rivelato una estensiva trascrizione di RNA non codificanti (ncRNA), le quali funzioni sono tuttavia in gran parte sconosciute. In questo lavoro è stato dimostrato che alte dosi di camptotecina (CPT), un farmaco antitumorale inibitore della Top1, aumentano la trascrizione di due ncRNA antisenso in 5’ e 3’ (5'aHIF-1α e 3'aHIF-1α rispettivamente) al locus genico di HIF-1α e diminuiscono i livelli dell’mRNA di HIF-1α stesso. Gli effetti del trattamento sono Top1-dipendenti, mentre non dipendono dal danno al DNA alla forca di replicazione o dai checkpoint attivati dal danno al DNA. I ncRNA vengono attivati in risposta a diversi tipi di stress, il 5'aHIF-1α è lungo circa 10 kb e possiede sia il CAP in 5’ sia poliadenilazione in 3’ (in letteratura è noto che il 3'aHIF-1α è un trascritto di 1,7 kb, senza 5’CAP né poliadenilazione). Analisi di localizzazione intracellulare hanno dimostrato che entrambi sono trascritti nucleari. In particolare 5'aHIF-1α co-localizza con proteine del complesso del poro nucleare, suggerendo un suo possibile ruolo come mediatore degli scambi della membrana nucleare. È stata dimostrata inoltre la trascrizione dei due ncRNA in tessuti di tumore umano del rene, evidenziandone possibili ruoli nello sviluppo del cancro. È anche noto in letteratura che basse dosi di CPT in condizioni di ipossia diminuiscono i livelli di proteina di HIF-1α. Dopo aver dimostrato su diverse linee cellulari che i due ncRNA sopracitati non potessero essere implicati in tale effetto, abbiamo studiato le variazioni dell’intero miRnoma alle nuove condizioni sperimentali. In tal modo abbiamo scoperto che il miR-X sembra essere il mediatore molecolare dell’abbattimento di HIF-1α dopo trattamento con basse dosi di CPT in ipossia. Complessivamente, questi risultati suggeriscono che il fattore di trascrizione HIF-1α venga finemente regolato da RNA non-codificanti indotti da danno al DNA.

Funktionelle Analyse der Polaritäts- und Tumorsuppressorgene hugl-1 und hugl-2 mittels siRNA-vermitteltem Gen-Silencing und konditionalem Gen-Knockout

Das menschliche Gen human giant larvae (hugl) ist ein Homolog des hochkonservierten Drosophila Gens lethal giant larvae (lgl), welches in Epithelzellen die Funktion eines neoplastischen Tumorsuppressors und Polaritätsregulators einnimmt. Ein Verlust oder eine verminderte Expression beider Homologe des Gens, hugl-1 und hugl-2, geht einher mit dem Auftreten und der Progression verschiedener epithelialer Tumorerkrankungen wie malignen Melanomen und Brust-, Kolon- oder Lungentumoren. Die exakte Funktion der Homologe Hugl-1 und Hugl-2 bezüglich der Regulation und Aufrechterhaltung der epithelialen Zellpolarität sowie ihre Rolle in der Genese humaner Tumore ist jedoch weitgehend unbekannt. Gänzlich unbekannt ist auch die Bedeutung von Hugl-1 und Hugl-2 als Polaritätsregulatoren für die Ausbildung und den Erhalt der T-Zellmorphologie und -funktion. Ziel der vorliegenden Arbeit war es daher, die Polaritäts- und Tumorsuppressorgene hugl-1 und hugl-2 in funktionellen Analysen mittels siRNA-vermitteltem Gen-Silencing in Epithelzellen und T-Lymphozyten zu charakterisieren. Darüber hinaus wurden die Funktionen und Eigenschaften von mgl-2, dem murinen Homologen von hugl-2, im Cre/loxP-vermittelten konditionalen Knockout Mausmodell in vivo analysiert.rnrnZur Charakterisierung der biologischen Effekte von Hugl-1 und Hugl-2 auf das Wachstumsverhalten, Migration und Invasion von Epithelzellen wurden in dieser Arbeit erfolgreich unterschiedliche shRNA-Expressionskonstrukte generiert sowie Hugl-supprimierte Zelllinien etabliert. In vitro Studien sowie in vivo Tumorigenizitätsanalysen lieferten übereinstimmend Hinweise darauf, dass verminderte Hugl-1- und Hugl-2-Expressionsspiegel eine signifikante Rolle in der Vermittlung invasiver und tumorigener Eigenschaften von Epithelzellen spielen. Dabei rief der Verlust beider Homologe deutlich stärkere Reaktionen hervor als die Suppression eines einzelnen Homologen. Zudem wiesen die Überexpression des Zellzyklusregulators Cyclin D1 sowie die Hyperproliferation von Hugl-1- und/oder Hugl-2-depletierten Epithelzellen auf eine wichtige Rolle der beiden Homologe in der Zellzyklusprogression und Zellproliferation hin. Ein geringer Expressionsstatus von Hugl-1 und -2 schien darüber hinaus mit einer verstärkten Resistenzbildung gegenüber Chemotherapeutika zu korrelieren. Im Rahmen dieser Arbeit konnte weiterhin gezeigt werden, dass die untersuchten T-Lymphozyten nur Hugl-1 exprimieren und dass letzteres notwendig für den F-Aktin-vermittelten Erhalt der T-Zellpolarität und -morphologie ist. Hugl-1-supprimierte, über voneinander unabhängige Signalwege (TCR- oder Chemokinrezeptor) stimulierte T-Lymphozyten wiesen eine bedeutende Störung der Lamellipodien- und Uropodausbildung auf und ließen eine Interaktion von Hugl-1 auf Ebene des F Aktins vermuten. Des Weiteren zeigte sich, dass der Polaritätsregulator Hugl-1 die CD3/TCR-induzierte Zelladhäsion positiv beeinflusst. Die Analyse der T-Zellmigration und -motilität offenbarte in Übereinstimmung dazu die Wichtigkeit von Hugl-1 für die Polarisierung und Migration der T-Zellen sowohl im Chemokingradienten als auch auf mDCs. rnrnFür die Aufklärung der funktionellen Rolle von mgl-2 in vivo wurde in dieser Arbeit eine Tamoxifen-induzierbare, Cre/loxP-vermittelte konditionale Mauslinie generiert und analysiert. Die mgl-2-deletierten Tiere wiesen weder signifikante phänotypische Unterschiede noch Abweichungen in der Organanatomie auf und ließen daher auf eine Kompensation durch das im Darmepithel koexprimierte und möglicherweise funktionell redundante mgl-1 Gen schließen.rn

Mutations of the transcription factor PU.1 are not associated with acute lymphoblastic leukaemia

The transcription factor PU.1 plays a crucial role during normal haematopoiesis in both myeloid cells and B-lymphocytes. Mice with a disruption in both alleles of the PU.1 locus were found to lack macrophages and B cells and had delayed appearance of neutrophils. In addition, critical decrease of PU.1 expression is sufficient to cause acute myeloid leukaemia (AML) and lymphomas in mice. Recently, we reported that heterozygous mutations in the PU.1 gene are present in some patients with AML. Thus, we hypothesised that PU.1 mutations might also contribute to the development of acute leukaemias of the B-cell lineage. Here, we screened 62 patients with B-cell acute lymphoblastic leukaemia (B-ALL) at diagnosis for genomic mutations by direct sequencing of all five exons of the PU.1 gene. We found no genomic alteration of the PU.1 gene suggesting that PU.1 mutations are not likely to be common in B-ALL.

Evidence that N-acetylcysteine inhibits TNF-alpha-induced cerebrovascular endothelin-1 upregulation via inhibition of mitogen- and stress-activated protein kinase

N-acetylcysteine (NAC) is neuroprotective in animal models of acute brain injury such as caused by bacterial meningitis. However, the mechanism(s) by which NAC exerts neuroprotection is unclear. Gene expression of endothelin-1 (ET-1), which contributes to cerebral blood flow decline in acute brain injury, is partially regulated by reactive oxygen species, and thus a potential target of NAC. We therefore examined the effect of NAC on tumor necrosis factor (TNF)-alpha-induced ET-1 production in cerebrovascular endothelial cells. NAC dose dependently inhibited TNF-alpha-induced preproET-1 mRNA upregulation and ET-1 protein secretion, while upregulation of inducible nitric oxide synthase (iNOS) was unaffected. Intriguingly, NAC had no effect on the initial activation (i.e., IkappaB degradation, nuclear p65 translocation, and Ser536 phosphorylation) of NF-kappaB by TNF-alpha. However, transient inhibition of NF-kappaB DNA binding suggested that NAC may inhibit ET-1 upregulation by inhibiting (a) parallel pathway(s) necessary for full transcriptional activation of NF-kappaB-mediated ET-1 gene expression. Similar to NAC, the MEK1/2 inhibitor U0126, the p38 inhibitor SB203580, and the protein kinase inhibitor H-89 selectively inhibited ET-1 upregulation without affecting nuclear p65 translocation, suggesting that NAC inhibits ET-1 upregulation via inhibition of mitogen- and stress-activated protein kinase (MSK). Supporting this notion, cotreatment with NAC inhibited the TNF-alpha-induced rise in MSK1 and MSK2 kinase activity, while siRNA knock-down experiments showed that MSK2 is the predominant isoform involved in TNF-alpha-induced ET-1 upregulation.

Upregulation of endothelin converting enzyme-1 in host liver during chronic cardiac allograft rejection

Endothelin regulates cytokine expression in vitro and in vivo. This study investigated the effects of chronic allograft rejection on hepatic endothelin-converting enzyme-1 (ECE-1) gene expression and endothelin-1 (ET-1) plasma clearance. Using the Lewis-F344 minor histocompatibility mismatch model of heterotopic cardiac transplantation, hepatic ECE-1 gene expression was measured by real-time polymerase chain reaction and host plasma clearance of ET-1 was measured 8 weeks after transplantation in the absence of immunosuppression. In animals undergoing allograft rejection, hepatic ECE-1 gene expression increased 2-fold (P < 0.05), whereas no effect of rejection on ET-1 clearance from plasma was observed. In summary, upregulation of ECE-1 gene expression occurs in the liver of the host during chronic allograft rejection. Because the liver represents both a key organ for cytokine production and for endothelin metabolism, increased hepatic ECE-1-mediated ET-1 synthesis may contribute to host responses and cytokine production during allograft rejection.

Heme oxygenase-1 is a critical regulator of nitric oxide production in enterohemorrhagic Escherichia coli-infected human enterocytes

Enterohemorrhagic Escherichia coli (EHEC) are the causative agent of hemolytic-uremic syndrome. In the first stage of the infection, EHEC interact with human enterocytes to modulate the innate immune response. Inducible NO synthase (iNOS)-derived NO is a critical mediator of the inflammatory response of the infected intestinal mucosa. We therefore aimed to analyze the role of EHEC on iNOS induction in human epithelial cell lines. In this regard, we show that EHEC down-regulate IFN-gamma-induced iNOS mRNA expression and NO production in Hct-8, Caco-2, and T84 cells. This inhibitory effect occurs through the decrease of STAT-1 activation. In parallel, we demonstrate that EHEC stimulate the rapid inducible expression of the gene hmox-1 that encodes for the enzyme heme oxygenase-1 (HO-1). Knock-down of hmox-1 gene expression by small interfering RNA or the blockade of HO-1 activity by zinc protoporphyrin IX abrogated the EHEC-dependent inhibition of STAT-1 activation and iNOS mRNA expression in activated human enterocytes. These results highlight a new strategy elaborated by EHEC to control the host innate immune response.

Localization of DJ-1 mRNA in the mouse brain

DJ-1 is mutated in autosomal recessive, early onset Parkinson's disease but the exact localization of the DJ-1 gene product in the mammalian brain is largely unknown. We aimed to evaluate the DJ-1 mRNA expression pattern in the mouse brain. Serial coronal sections of brains of five male and five female adult mice were investigated by using in situ hybridization with a DJ-1 specific 35S-labeled oligonucleotide probe. Hybridized sections were analyzed after exposure to autoradiography films and after coating with a photographic emulsion. DJ-1 was heterogeneously expressed throughout the mouse central nervous system. A high expression of DJ-1 mRNA was detected in neuronal and non-neuronal populations of several structures of the motor system such as the substantia nigra, the red nucleus, the caudate putamen, the globus pallidus, and the deep nuclei of the cerebellum. Furthermore, DJ-1 mRNA was also highly expressed in non-motor structures including the hippocampus, the olfactory bulb, the reticular nucleus of the thalamus, and the piriform cortex. The high expression of DJ-1 mRNA in brain regions involved in motor control is compatible with the occurrence of parkinsonian symptoms after DJ-1 mutations. However, expression in other regions indicates that a dysfunction of DJ-1 may contribute to additional clinical features in patients with a DJ-1 mutation.

Human NR5A1/SF-1 mutations show decreased activity on BDNF (brain-derived neurotrophic factor), an important regulator of energy balance: testing impact of novel SF-1 mutations beyond steroidogenesis

CONTEXT Human NR5A1/SF-1 mutations cause 46,XY disorder of sex development (DSD) with broad phenotypic variability, and rarely cause adrenal insufficiency although SF-1 is an important transcription factor for many genes involved in steroidogenesis. In addition, the Sf-1 knockout mouse develops obesity with age. Obesity might be mediated through Sf-1 regulating activity of brain-derived neurotrophic factor (BDNF), an important regulator of energy balance in the ventromedial hypothalamus. OBJECTIVE To characterize novel SF-1 gene variants in 4 families, clinical, genetic and functional studies were performed with respect to steroidogenesis and energy balance. PATIENTS 5 patients with 46,XY DSD were found to harbor NR5A1/SF-1 mutations including 2 novel variations. One patient harboring a novel mutation also suffered from adrenal insufficiency. METHODS SF-1 mutations were studied in cell systems (HEK293, JEG3) for impact on transcription of genes involved in steroidogenesis (CYP11A1, CYP17A1, HSD3B2) and in energy balance (BDNF). BDNF regulation by SF-1 was studied by promoter assays (JEG3). RESULTS Two novel NR5A1/SF-1 mutations (Glu7Stop, His408Profs*159) were confirmed. Glu7Stop is the 4th reported SF-1 mutation causing DSD and adrenal insufficiency. In vitro studies revealed that transcription of the BDNF gene is regulated by SF-1, and that mutant SF-1 decreased BDNF promoter activation (similar to steroid enzyme promoters). However, clinical data from 16 subjects carrying SF-1 mutations showed normal birth weight and BMI. CONCLUSIONS Glu7Stop and His408Profs*159 are novel SF-1 mutations identified in patients with 46,XY DSD and adrenal insufficiency (Glu7Stop). In vitro, SF-1 mutations affect not only steroidogenesis but also transcription of BDNF which is involved in energy balance. However, in contrast to mice, consequences on weight were not found in humans with SF-1 mutations.

Towards the identification of a tumor suppressor gene on chromosome 3p12: Physical mapping and candidate gene screening

Renal cell carcinoma (RCC) is the most common malignant tumor of the kidney. Characterization of RCC tumors indicates that the most frequent genetic event associated with the initiation of tumor formation involves a loss of heterozygosity or cytogenetic aberration on the short arm of human chromosome 3. A tumor suppressor locus Nonpapillary Renal Carcinoma-1 (NRC-1, OMIM ID 604442) has been previously mapped to a 5–7 cM region on chromosome 3p12 and shown to induce rapid tumor cell death in vivo, as demonstrated by functional complementation experiments. ^ To identify the gene that accounts for the tumor suppressor activities of NRC-1, fine-scale physical mapping was conducted with a novel real-time quantitative PCR based method developed in this study. As a result, NRC-1 was mapped within a 4.6-Mb region defined by two unique sequences within UniGene clusters Hs.41407 and Hs.371835 (78,545Kb–83,172Kb in the NCBI build 31 physical map). The involvement of a putative tumor suppressor gene Robo1/Dutt1 was excluded as a candidate for NRC-1. Furthermore, a transcript map containing eleven candidate genes was established for the 4.6-Mb region. Analyses of gene expression patterns with real-time quantitative RT-PCR assays showed that one of the eleven candidate genes in the interval (TSGc28) is down-regulated in 15 out of 20 tumor samples compared with matched normal samples. Three exons of this gene have been identified by RACE experiments, although additional exon(s) seem to exist. Further gene characterization and functional studies are required to confirm the gene as a true tumor suppressor gene. ^ To study the cellular functions of NRC-1, gene expression profiles of three tumor suppressive microcell hybrids, each containing a functional copy of NRC-1, were compared with those of the corresponding parental tumor cell lines using 16K oligonucleotide microarrays. Differentially expressed genes were identified. Analyses based on the Gene Ontology showed that introduction of NRC-1 into tumor cell lines activates genes in multiple cellular pathways, including cell cycle, signal transduction, cytokines and stress response. NRC-1 is likely to induce cell growth arrest indirectly through WEE1. ^

Genome-wide gene-gene interaction analysis for cardiovascular disease

Numerous studies have been carried out to try to better understand the genetic predisposition for cardiovascular disease. Although it is widely believed that multifactorial diseases such as cardiovascular disease is the result from effects of many genes which working alone or interact with other genes, most genetic studies have been focused on identifying of cardiovascular disease susceptibility genes and usually ignore the effects of gene-gene interactions in the analysis. The current study applies a novel linkage disequilibrium based statistic for testing interactions between two linked loci using data from a genome-wide study of cardiovascular disease. A total of 53,394 single nucleotide polymorphisms (SNPs) are tested for pair-wise interactions, and 8,644 interactions are found to be significant with p-values less than 3.5×10-11. Results indicate that known cardiovascular disease susceptibility genes tend not to have many significantly interactions. One SNP in the CACNG1 (calcium channel, voltage-dependent, gamma subunit 1) gene and one SNP in the IL3RA (interleukin 3 receptor, alpha) gene are found to have the most significant pair-wise interactions. Findings from the current study should be replicated in other independent cohort to eliminate potential false positive results.^

Regulation of Bcl-2 expression by the product of the prostate apoptosis response gene -4, Par-4

Elevated expression levels of the bcl-2 proto-oncogene have been correlated with the appearance of androgen independence in prostate cancer. Although bcl-2 was first cloned as the t (14:18) translocation breakpoint from human follicular B cell lymphoma, the mechanism of overexpression of bcl-2 is largely undefined for advanced prostate cancer, there being no gross alterations in the gene structure. We investigated the role of the product of the prostate apoptosis response gene-4 (Par-4) and the product of the Wilms' tumor 1 gene (WT1) in the regulation of Bcl-2 expression in prostate cancer cell lines. We observed growth arrest and apoptosis, upon decreasing Bcl-2 protein and transcript in the high Bcl-2 expressing, androgen-independent prostate cancer cell lines, by all trans-retinoic acid treatment but this did not occur in the androgen-dependent cell lines expressing low levels of Bcl-2. Changes in localization of Par-4, and an induction in the expression of WT1 protein accompanied the decrease in the Bcl-2 protein and transcript following all trans-retinoic acid treatment, in the androgen-independent prostate cancer cell line. In stable clones expressing ectopic Par-4 we observed decreased Bcl-2 protein and transcript. This was accompanied by an induction in WT1 expression. Finally, we detected Par-4 and WT1 proteins binding to a previously identified WT1 binding site on the bcl-2 promoter both in vitro and in vivo leading to a decrease in transcription from the bcl-2 promoter. We conclude that Par-4 regulates Bcl-2 through a WT1 binding site on the bcl-2 promoter. ^

Characterization of the NOP -1 opsin photoreceptor in the filamentous fungus Neurospora crassa

Light absorption is an important process for energy production and sensory perception in many organisms. In the filamentous fungus, Neurospora crassa, blue-light is an important regulator of both asexual and sexual development, but the identity of the blue-light receptor is unknown. The work presented in this dissertation initiated the characterization of the putative N. crassa opsin photoreceptor, NOP-1. Opsins were thought to exist only in the archaea and mammals until the discovery of nop-1. All opsins have the same conserved structure of seven transmembrane helical domains with a lysine residue in the seventh helix specific for forming a Schiff-base linkage with retinal. The predicted NOP-1 protein sequence is equally similar to archaeal rhodopsins and a newly identified fungal opsin-related protein group (ORPs). ORPs maintain the seven transmembrane helical structure of opsins, but lack the conserved lysine residue for binding retinal. An ORP gene, orp-1 was identified in N. crassa and this work includes the cloning and sequence analysis of this gene. Characterization of NOP-1 function in N. crassa development began with the construction of a Δnop-1 deletion mutant. Extensive phenotypic analysis of Δnop-1 mutants revealed only subtle defects during development primarily under environmental conditions that induce a stress response. NOP-1 was overexpressed in the heterologous system Pichia pastoris, and it was demonstrated that NOP-1 protein bound all-trans retinal to form a green-light absorbing pigment (λmax = 534 nm) with a photochemical reaction cycle similar to archaeal sensory rhodopsins. nop-1 gene expression was monitored during N. crassa development. nop-1 transcript is highly expressed during asexual sporulation (conidiation) and transcript levels are abundant in the later stages of conidial development. nop-1 expression is not regulated by blue-light or elevated temperatures. Potential functions for NOP-1 were discovered through the transcriptional analysis of conidiation-associated genes in Δnop-1 mutants. NOP-1 exhibits antagonistic transcriptional regulation of conidiation-associated genes late in conidial development, by enhancing the carotenogenic gene, al-2 and repressing the conidiation-specific genes, con-10 and con-13. ^