CGS 8216: receptor binding characteristics of a potent benzodiazepine antagonist

CGS 8216 is a novel nonbenzodiazepine that inhibited 3H-flunitrazepam (3H-FLU) binding to rat synaptosomal membranes in vitro at subnanomolar concentrations. It prevented the in vivo labeling of brain benzodiazepine receptors by 3H-FLU with the same potency as diazepam when given orally to mice. Pharmacologic tests showed that it was devoid of benzodiazepine-like activity but it antagonized the actions of diazepam in these tests. It did not interact with alpha- or beta- adrenergic, H1-histaminergic or GABA receptors but it inhibited adenosine-activation of cyclic AMP formation. Studies with 3H-CGS 8216 demonstrated that it bound specifically and with high affinity to rat forebrain membranes and was displaced by drugs with an order of potencies similar to that observed when 3H-diazepam and 3H-FLU were used as radioligands. The regional distribution of 3H-CGS 8216 binding sites in the brain was also similar to that of 3H-FLU. Dissociation of 3H-CGS 8216 binding was slow at 0 degrees C but increased with temperature and was almost complete within 1 min at 37 degrees C. Scatchard analyses were linear, yielding KD values of 0.044, 0.11 and 0.18 nM at 0, 25 and 37 degrees C, respectively; the Bmax value did not change appreciably with temperature and was approximately 1000 fmoles/mg protein. Using 3H-FLU, the value for Bmax as well as for the KD increased with temperature. The total number of binding sites determined for 3H-FLU was greater than that for 3H-CGS 8216 at each temperature. CGS 8216 exhibited mixed-type inhibition of 3H-FLU binding. GABA did not stimulate 3H-CGS 8216 binding whereas it enhanced 3H-FLU binding. CGS 8216 may be a useful ligand for probing the antagonist properties of the benzodiazepine receptor and is likely to exhibit interesting therapeutic effects.

Racial differences in optic nerve head parameters

Results of previous studies have strongly indicated that the prevalence of elevated intraocular pressure is greater in blacks than in whites and that blacks are more susceptible than whites to glaucomatous damage at any given level of pressure. It has also been suggested that a larger disc area might predispose an eye to glaucomatous damage. We investigated the possibility that clinically quantifiable differences might exist in optic disc parameters between normotensive white and black patients. Disc area, cup-to-disc ratio, and cup volume measured with a video-ophthalmograph (Rodenstock Optic Disc Analyzer) were significantly larger in blacks than in whites, while there was no difference in the disc rim area between the two groups. We derived a mathematical model of the optic disc that relates posterior displacement of the lamina cribrosa to the disc area, distensibility of the disc, and intraocular pressure.

ALX 5407: a potent, selective inhibitor of the hGlyT1 glycine transporter

High-affinity glycine transport in neurons and glial cells is a primary means of inactivating synaptic glycine. We have synthesized a potent selective inhibitor of glycine transporter 1 (GlyT1), and characterized its activity using a quail fibroblast cell line (QT6). The glycine transporters GlyT1A, GlyT1B, GlyT1C, and GlyT2 were stably expressed in QT6 cells. The transporters expressed in these cells exhibited appropriate characteristics as described previously for these genes: Na(+)/Cl(-) dependence, appropriate K(m) values for glycine uptake, and appropriate pharmacology, as defined in part by the ability of N-methyl glycine (sarcosine) to competitively inhibit glycine transport. Furthermore, the characteristics of the transporters in the cell lines recapitulate the characteristics of glycine transporters observed in tissue preparations. We developed a sarcosine derivative, (R)-(N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl])sarcosine (ALX 5407), and examined its activity against the cloned glycine transporters. ALX 5407 completely inhibited glycine transport in the GlyT1 cells, with an IC(50) value of 3 nM, but had little or no activity at the human GlyT2 transporter, at other binding sites for glycine, or at other neurotransmitter transporters. The inhibition of glycine transport was essentially irreversible. ALX 5407 represents a novel tool in the investigation of N-methyl-D-aspartate-receptor function. This class of drug may lead to novel therapies in the treatment of schizophrenia.

Biocompatibility of chemical-vapour-deposited diamond

The biocompatibility of chemical-vapour-deposited (CVD) diamond surfaces has been assessed. Our results indicate that CVD diamond is as biocompatible as titanium (Ti) and 316 stainless steel (SS). First, the amount of adsorbed and 'denatured' fibrinogen on CVD diamond was very close to that of Ti and SS. Second, both in vitro and in vivo there appears to be less cellular adhesion and activation on the surface of CVD diamond surfaces compared to Ti and SS. This evident biocompatibility, coupled with the corrosion resistance and notable mechanical integrity of CVD diamond, suggests that diamond-coated surfaces may be highly desirable in a number of biomedical applications.

Radical retropubic prostatectomy: bladder neck preservation versus reconstruction

PURPOSE

We compare bladder neck contracture, urinary continence and positive surgical margin rates after bladder neck preservation and excision with radical retropubic prostatectomy.

MATERIALS AND METHODS

A retrospective analysis of clinical and pathological findings, and followup of 220 patients who underwent radical retropubic prostatectomy was performed. Patients were divided into 3 groups of bladder neck preservation (101), "tennis racket" reconstruction (63) and anterior bladder tube reconstruction (56).

RESULTS

Mean followup was 19.7, 36.7 and 16.2 months, respectively, for bladder neck preservation, tennis racket reconstruction and anterior bladder tube reconstruction. Overall, bladder neck contracture occurred in 22 of 220 cases (10%), including 5 of 101 (5%) with bladder neck preservation, 7 of 63 (11%) with tennis racket reconstruction and 10 of 56 (18%) with anterior bladder tube reconstruction, which approached statistical significance (p = 0.061). Urinary continence was assessed by a third party telephone interview of 165 patients. Continence rates at 1 year were 93% for bladder neck preservation, 96% for tennis racket reconstruction and 97% for anterior bladder tube reconstruction, which was not statistically significant (p = 0.68). Positive margin rates were 27.4% with bladder neck preservation versus 30.5% with excision, which was not significantly different.

CONCLUSIONS

There are no statistically significant differences in return of urinary continence, bladder neck contracture rates or positive margins between bladder neck preservation and excision.

Genetic grouping for the isolates of avian infectious bronchitis virus in Taiwan

In order to differentiate recent isolates of avian infectious bronchitis virus (IBV) in Taiwan, polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and direct sequencing methods were used to type 25 IBV Taiwan isolates. Two conserved sequences that flank the hypervariable region I (HVR I) in the N-terminus of S1 protein gene were chosen as primers. Sequences of 228-231 base pairs (bp) were amplified by PCR from 25 Taiwan isolates and 4 reference strains (H120, Conn, JMK, Holte). PCR products were digested with 5 restriction endonucleases, BsoFI, DdeI, MboII, AluI, RsaI, and different IBV isolates were grouped according to their RFLP patterns. The RFLP patterns of the 4 reference strains in this study matched the published sequences in GenBank. Except 1 vaccine strain, the other 24 Taiwan isolates were different from these 4 and 18 other IBV strains whose sequences were published. The data from PCR-RFLP and sequencing of IBV genomes showed that the 24 Taiwan isolates can be divided into 2 distinct groups, I and II. Seven RFLP patterns are identified in group I and only 1 in group II.

Glycation mediated lens crystallin aggregation and cross-linking by various sugars and sugar phosphates in vitro

Glycation of lens crystallins results in protein conformational changes, oxidation, browning and aggregation. Though glucose is the major sugar, other sugars and sugar phosphates generated as intermediates of metabolic pathways are present in the lens, albeit at low concentrations. In this study we incubated bovine lens soluble fraction with various sugars and sugar phosphates (5mM for 10 days). The reactivity was in the order trioses > tetroses > pentoses > hexoses. High molecular weight (HMW) aggregates were also formed at a comparable rate. Increased levels of fluorescence were associated with the HMW aggregates with fast reacting sugars. The phosphorylated derivatives were only slightly more reactive than their respective sugars. Interestingly, fructose-1,6-diphosphate was more reactive and cross-linked more readily than fructose-6-phosphate. Gel electrophoresis under reducing and nonreducing conditions showed formation of disulfide linked protein aggregates with slow reacting sugars such as glucose and non-disulfide covalent linked protein aggregates with fast reacting sugars such as erythrose. In contrast, if 0.1 m DTT was present in erythrose incubations (a fast reacting sugar), the HMW aggregate formation was significantly reduced. In order to show the reactivity among the slow reacting hexoses, we incubated lens proteins with 1 M hexoses for 30 days and the results showed that galactose was more reactive and showed higher cross-linking than fructose and glucose. These results thus indicate that relatively low levels of some sugars and sugar phosphates in the lens could be compensated by enhanced lens protein cross-linking and the combined effect could be rather significant with respect to cataractogenesis.

Gap gene properties of the pair-rule gene runt during Drosophila segmentation

The Drosophila Runt protein is a member of a new family of transcriptional regulators that have important roles in processes extending from pattern formation in insect embryos to leukemogenesis in humans. We used ectopic expression to investigate runt's function in the pathway of Drosophila segmentation. Transient over-expression of runt under the control of a Drosophila heat-shock promoter caused stripe-specific defects in the expression patterns of the pair-rule genes hairy and even-skipped but had a more uniform effect on the secondary pair-rule gene fushi tarazu. Surprisingly, the expression of the gap segmentation genes, which are upstream of runt in the segmentation hierarchy was also altered in hs/runt embryos. A subset of these effects were interpreted as due to an antagonistic effect of runt on transcriptional activation by the maternal morphogen bicoid. In support of this, expression of synthetic reporter gene constructs containing oligomerized binding sites for the Bicoid protein was reduced in hs/runt embryos. Finally, genetic experiments demonstrated that regulation of gap gene expression by runt is a normal component of the regulatory program that generates the segmented body pattern of the Drosophila embryo.

Comparative physical and genetic maps of the virulence plasmids of Salmonella enterica serovars typhimurium, enteritidis, choleraesuis, and dublin

Using fragment profiling, PCR, and Southern hybridization, we found that Salmonella enterica serovar Choleraesuis harbored virulence plasmids of various sizes, whereas serovars Typhimurium, Enteritidis, and Dublin carried a plasmid of a unique size. Also, the virulence plasmid of Typhimurium contained genes in the same order detected in the other three plasmids, all of which contained deletions.

Responsiveness of human T lymphocytes to bacterial superantigens presented by cultured rheumatoid arthritis synoviocytes

OBJECTIVE

Type B fibroblastic synoviocytes are abundant in inflamed joints of patients with rheumatoid arthritis (RA), and can secrete cytokines and other mediators of inflammation. The aim of this study was to determine whether cell lines derived from RA type B synoviocytes could also serve as accessory cells for T lymphocyte activation.

METHODS

Cells from RA synoviocyte lines, with or without preculture in interferon-gamma (IFN gamma), were cultured with purified peripheral blood T cells, in the presence or absence of superantigens or other accessory cell-dependent T cell mitogens. T cell proliferation was measured by thymidine incorporation, and synoviocyte surface markers were analyzed by flow cytometry.

RESULTS

RA type B synoviocyte lines were potent accessory cells for T cell responses to bacterial superantigens or lectins, and direct cell-cell contact was required. Preculture in IFN gamma augmented synoviocyte expression of major histocompatibility complex (MHC) class II molecules and of ligands for some T cell costimulatory receptors, but synoviocyte accessory cell function was evident even in the absence of IFN gamma. Blocking studies using monoclonal antibodies supported the notion of a role CD2, CD11a/CD18 and MHC class II molecules in synoviocyte-dependent T cell activation. Monoclonal antibodies against IFN gamma, interleukin-1 beta (IL-1 beta), IL-6, IL-8, and tumor necrosis factor alpha failed to block the T cell proliferative responses, but anti-IL-2 was strongly inhibitory.

CONCLUSION

Cultured RA and type B synoviocytes can perform some of the functions of professional antigen-presenting cells. If such cells have similar properties in vivo, they may be important participants in activation of immune responses, in addition to their previously described synthetic and proinflammatory roles. If RA synovial tissue T cells, like normal peripheral blood T cells, can respond to superantigens presented by synoviocytes, this interaction could be important in the pathogenesis of RA.

CGS 19755 is a potent and competitive antagonist at NMDA-type receptors

The N-Methyl-D-aspartate (NMDA)-type receptor blocking properties of CGS 19755, a novel, rigid analog of 2-amino-5-phosphonopentanoate, were demonstrated in vitro by the ability of the compound to block NMDA-evoked [3H]acetylcholine release (pA2 = 5.93). CGS 19755 (0.045 and 0.224 mmol/kg i.p.) was shown to be active in vivo as well by its ability to block harmaline-induced increases in cerebellar cGMP. Finally, CGS 19755 blocked sound-induced seizures in DBA/2 mice completely at doses of 1.0 nmol i.c.v. or 0.1 mmol/kg i.p. Taken together, these data indicate that CGS 19755 is a potent and competitive NMDA antagonist in vitro which is also active in vivo.

Improvement of Schwann cell attachment and proliferation on modified hyaluronic acid strands by polylysine

Hyaluronic acid (HyA) has the intrinsic ability to promote cell proliferation and reduce scar formation. However, the clinical use of HyA has so far been limited because of its water solubility and nonadhesive characteristics. Increasing interest in HyA as a clinically useful biomaterial has prompted our study of altering HyA's physical properties to render it a potential component of nerve grafts. In this study, strands of HyA were cross-linked by glutaraldehyde (Glut), coated with polylysine, and then inoculated with Schwann cells (SCs). Results in vivo and in vitro demonstrated that cross-linked HyA strands were water insoluble and thus less biodegradable. Poly-D-lysine-resurfaced strands showed significant SC attachment of 350-400 cells/mm(2), compared to uncoated controls (0-10 cells/mm(2), p < 0.01). Fibroblast control groups showed an attachment of 40-100 cells/mm(2) on coated strands. Immunostaining for proliferating cells showed SCs as and fibroblasts as +. Cells neither adhered to nor proliferated on the modified HyA strands that were not resurfaced. The results suggest that polylysine promotes SC attachment and proliferation to glutaraldehyde-cross-linked HyA strands, the product being a three-dimensional composite with low solubility that may have potential application in nerve grafts.

Homocysteic acid as a putative excitatory amino acid neurotransmitter: I. Postsynaptic characteristics at N-methyl-D-aspartate-type receptors on striatal cholinergic interneurons

The actions of the stereoisomers of homocysteic acid (HCA) were characterized at N-methyl-D-aspartate (NMDA)-type receptors which mediate excitatory amino acid-evoked [3H]acetylcholine ([3H]ACh) release from striatal cholinergic interneurons. Like NMDA, L-HCA and D-HCA evoked the release of [3H]ACh formed from [3H]choline in striatal slices. The concentration-response curve for L-HCA was virtually superimposable on that for NMDA, yielding an equal EC50 value (56.1 microM) and maximal response. However, D-HCA was weaker, with an EC50 value of 81.1 microM, and an apparently smaller maximal response. L-HCA-evoked [3H]ACh release was inhibited by the same categories of compounds which inhibit NMDA-evoked [3H]ACh release: the divalent ion Mg2+ (IC50 = 25.8 microM); competitive NMDA antagonists 2-amino-7-phosphonoheptanoate (IC50 = 51.2 microM) and 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (IC50 = 20.1 microM); and the dissociative anesthetics tiletamine (IC50 = 0.59 microM) and MK-801 (IC50 = 0.087 microM). Like NMDA, L-HCA produced a tachyphylaxis in this system. Tachyphylaxis to NMDA resulted in a decrease response to L-HCA, and conversely, tachyphylaxis to L-HCA resulted in a decrease response to NMDA. The results suggest that L-HCA is an agonist at the NMDA-type receptor and may represent an endogenous ligand for this excitatory amino acid receptor.

Inhibition of neuronal activity of the substantia nigra by noxious stimuli and its modification by the caudate nucleus

In urethane-anesthetized rats discharges of neurons of substantia nigra, pars compacta (SNC) were recorded extracellularly after natural somatic sensory stimulation and electrical stimulation of peripheral sensory nerves. (1) Among different modalities of somatic sensory stimulation tested, noxious stimuli were effective in reducing spontaneous discharges of SNC neurons. The inhibition appeared with a concomitant increase of spike amplitude. The same inhibitory effect was obtained by stimulating the sciatic nerve (SC) repetitively. In response to single shock stimulation of the SC the inhibition occurred at an average latency of 39.6 msec (S.E. 1.6 msec) and lasted for 221.6 msec on average (S.E. 10.8 msec). (2) The SC-induced inhibition of SNC neurons failed to reliably block ortho- and antidromic discharges evoked from the caudate nucleus (Cd). (3) In rats with the Cd lesioned the SC-induced inhibition was longer lasting than in controls. When the Cd was stimulated concurrently with SC stimulation, the inhibition from the SC was weakened. (4) In a majority of SNC neurons, their inhibition by SC stimulation, their inhibition by SC stimulation was antagonized by intravenous injection of haloperidol.

Electronic-based lifestyle interventions in overweight or obese perinatal women: a systematic review and meta-analysis

Electronic-based (e-based) lifestyle interventions provide potential and cost-effective delivery of remote interventions for overweight and obese perinatal women. To date, no meta-analysis has reported the efficacy of maternal and neonatal outcomes. Seven electronic databases were searched from inception up to July 13, 2016, including the Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, EMBASE, ProQuest Dissertations and Theses, PsycINFO, PubMed and Scopus. Among the 1,145 studies retrieved, 14 randomized controlled trials were selected among 17 publications. The Cochrane risk of bias tool was used to appraise the quality assessment. The meta-analyses demonstrated a significant result for limiting gestational weight gain, losing postnatal weight in 1-2 months, increasing self-reported moderate and vigorous physical activity and reducing caloric intake using diet-related software. Our review shows that an e-based lifestyle intervention is an acceptable approach. The findings reveal the variability in intervention methods and provide limited conclusive evidence. Thus, future studies should examine the efficacy and essential components as well as the various approaches using optimal portions of in-person and phone sessions. Further evaluations comparing the effectiveness of different e-based lifestyle intervention approaches toward activity-related and diet-related outcomes are necessary.

Subpallidal-pedunculopontine projections but not subpallidal-mediodorsal thalamus projections contribute to spontaneous exploratory locomotor activity

The contribution of the pedunculopontine nucleus to exploratory locomotion was investigated in rats. Locomotor activity recorded in a standard open-field apparatus was increased more than two-fold when wooden panels were inserted. This novelty-elicited locomotion was reduced significantly when procaine was injected bilaterally into the pedunculopontine nucleus but not when procaine was injected bilaterally into the mediodorsal thalamus, a second major projection site of the subpallidal area. These results support observations from earlier studies implicating hippocampal-accumbens-subpallidal-pedunculopontine projections in exploratory locomotion.

Epigenetic therapies by targeting aberrant histone methylome in AML: molecular mechanisms, current preclinical and clinical development

While the current epigenetic drug development is still largely restricted to target DNA methylome, emerging evidence indicates that histone methylome is indeed another major epigenetic determinant for gene expression and frequently deregulated in acute myeloid leukaemia (AML). The recent advances in dissecting the molecular regulation and targeting histone methylome in AML together with the success in developing lead compounds specific to key histone methylation-modifying enzymes have revealed new opportunities for effective leukaemia treatment. In this article, we will review the emerging functions of histone methyltransferases and histone demethylases in AML, especially MLL-rearranged leukaemia. We will also examine recent preclinical and clinical studies that show significant promises of targeting these histone methylation-modifying enzymes for AML treatment.

Statin use reduces the risk of dementia in elderly patients: a nationwide data survey and propensity analysis

OBJECTIVES

The objective of this study was to examine the association between the use of statins and the risk of newly diagnosed dementia in an elderly population.

DESIGN, SETTING AND PARTICIPANTS

Random samples of 1,000,000 individuals covered by the National Health Insurance in Taiwan were included in the analysis. All participants were 65 years or older without dementia and either did or did not start treatment with statins from 1 August 1997 to 31 December 2010. Patients with established dementia before the start of treatment were excluded. Baseline characteristics were matched (by propensity score) in those who did and did not receive statins.

RESULTS

A total of 57,669 subjects were included in the analysis with approximately 12 years of follow-up. Propensity score matching identified 2003 patients who received statins and another 2003 patients who did not with comparable baseline characteristics. Adjusted hazard ratios (HRs) for dementia were significantly inversely associated with total or daily equivalent statin dosage (total accumulated dose: HRs 0.829, 0.720 and 0.385 from T1 to T3 vs. control, P < 0.001 for trend; mean daily dose: HRs 0.667, 0.798 and 0.503 from T1 to T3 vs. control, P < 0.001). The results remained robust after propensity adjustment.

CONCLUSION

Independent of traditional risk factors, there was a decrease in newly diagnosed cases of dementia in elderly patients who had received a high total or daily dose of statins. The more potent statins (e.g. atorvastatin and rosuvastatin) seemed to be particularly effective in the prevention of dementia.

Two distinct lineages of macaque gamma herpesviruses related to the Kaposi's sarcoma associated herpesvirus

BACKGROUND

KSHV, Kaposi's sarcoma-associated herpesvirus, is a necessary cofactor for the development of Kaposi's sarcoma (KS). We have previously reported KSHV-related DNA sequences in retroperitoneal fibromatosis (RF) tissue from two species of macaque. The putative herpesvirus was called RFHV for RF-associated herpesvirus. These data suggested that KSHV is a human representative of a larger family of primate herpesviruses.

OBJECTIVE

To identify and characterize other members of a putative family of KSHV-related herpesviruses in macaques in order to obtain information on the evolutionary history of KSHV infection in humans.

STUDY DESIGN

Lymphoid tissue cells and blood leukocytes from rhesus-, cynomolgus- and pigtailed-macaques were tested for the presence of unknown herpesviruses using degenerate primer-driven PCR amplification. The sequences obtained were compared against known herpesvirus sequences.

RESULTS

We have identified new herpesvirus DNA sequences in each of the three macaque species. Sequence comparisons indicate that these new viruses are most related to each other and form a separate phylogenetic lineage within the gamma herpesviruses. Screening of PBMC from Indonesian-origin quarantine animals suggests that these viruses (MGV, macaque gamma virus) are species-specific, and highly prevalent in the wild. They are readily cultured in vivo, and share a common tissue tropism with the previously identified RFHV.

CONCLUSIONS

MGV and RFHV represent two independent introductions of an ancestral gamma herpesvirus into macaque precursors.

Demonstrating the pharmacogenetic effects of angiotensin-converting enzyme inhibitors on long-term prognosis of diastolic heart failure

The objective of this study was to evaluate the effects of angiotensin-converting enzyme (ACE) inhibitors and pharmacogenetic interaction on the survival of the patients with diastolic heart failure (DHF). A total of 285 subjects with DHF confirmed by echocardiography were recruited in the period between 1995 and 2003. Baseline characteristics (age, sex, prior history, medication, and echocardiographic findings) and genetic polymorphisms (ACE gene insertion/deletion (I/D) polymorphism; T174M, M235T, G-6A, A-20C, G-152A, and G-217A polymorphisms of the angiotensinogen (AGT) gene; and A1166C polymorphisms of the angiotensin II type I receptor (AT1R)) were collected and matched (by propensity score) in those who received and those who did not receive ACE inhibitors. The patients were followed up to 10 years. Kaplan-Meier curves and Cox regression models were used to demonstrate the survival trend. The 85 patients who received ACE inhibitors and the other 85 patients who did not were found to have comparable baseline characteristics and polymorphism distribution. Prescription of ACE inhibitors was associated with a significant decrease in overall mortality (hazard ratio (HR), 0.45; 95% confidence interval (CI), 0.24-0.83; P=0.01), and a lower rate of cardiovascular events at 4000 days (HR, 0.53; 95% CI, 0.32-0.90; P=0.02). In addition, ACE I/D gene D allele was associated with higher overall mortality as compared with the I allele (HR, 2.04; P=0.003). This effect was diminished in those who received ACE inhibitors. The use of ACE inhibitor was associated with a significant decrease in long-term mortality and cardiovascular events in the patients with DHF. Genetic variants in the renin-angiotensin system genes were also associated, but their effects could be modified by the use of ACE inhibitors.

A role for ultraspiracle, the Drosophila RXR, in morphogenetic furrow movement and photoreceptor cluster formation

Many of the same genes needed for proper eye and limb development in vertebrates, such as hairy, hedgehog, patched and cyclic AMP-dependent protein kinase A, are responsible for patterning Drosophila imaginal discs, the tissues that will give rise to the adult cuticle structures. This is well demonstrated in the control of morphogenetic furrow movement and differentiation in the eye imaginal disc. We report that ultraspiracle, the gene encoding the Drosophila cognate of the Retinoid X Receptor, is required for normal morphogenetic furrow movement and ommatidial cluster formation. Examination of the expression of genes involved in regulating the furrow suggests that ultraspiracle defines a novel regulatory pathway in eye differentiation.

Pair-rule expression of the Drosophila fushi tarazu gene: a nuclear receptor response element mediates the opposing regulatory effects of runt and hairy

The segmentation genes runt and hairy are required for the proper transcriptional regulation of the pair-rule gene fushi tarazu during the blastoderm stage of Drosophila embryogenesis. The expression of different fushi tarazu reporter genes was examined in runt and hairy mutant embryos, as well as in runt over-expressing embryos in order to identify DNA elements responsible for mediating these regulatory effects. The results indicated that runt and hairy act through a common 32 base-pair element. This element, designated as fDE1, contains a binding site for a small family of orphan nuclear receptor proteins that are uniformly expressed in blastoderm embryos. The pair-rule expression of reporter gene constructs containing multimerized fDE1 elements depends on activation by runt and repression by hairy. Examination of reporter genes with mutated fDE1 elements provided further evidence that this element mediates both transcriptional activation and repression. Genetic experiments indicated that the opposing effects of runt and hairy were not due solely to cross-regulatory interactions between these two genes and that fDE1-dependent expression is regulated by factors in addition to runt and hairy.