Two-Step Synthesis of Boron-Fused Double Helicenes

Novel boron-fused double [5]­helicenes were synthesized from hexabromobenzene in two steps via Hart reaction and demethylative cyclization. The parent helicene shows excellent ambipolar conductivity, which can be explained by unique 3D π-stacking with a brickwork arrangement. Moreover, the introduction of four <i>tert</i>-butyl groups suppresses racemization, enabling optical resolution. The enantiomerically pure helicene shows deep blue fluorescence with Commission Internationale de l′Eclairage coordinates of (0.15, 0.08) and circularly polarized luminescence activity

Increased levels of vesicle proteins in the <i>pag-3(gv650)</i> mutant are dependent on wild type IDA-1 activity.

<p>(A) Complete loss of IDA-1 activity due to the <i>ida-1</i> null deletion allele <i>ok409</i> results in a moderate, but significant, reduction in the levels of some vesicle-associated proteins (SNT-1 and RAB-3, *P<0.05) as indicated quantitatively at left and by Western blot signal to the right. All values are given as a percentage of wild type that is arbitrarily set to 100% as indicated by an open box. Error bars indicated variation of individual antibody level. (B) The level of the vesicle cargo component serotonin was compared in HSN neurons by immunofluorescent staining in the indicated four strains. Images show close up of HSN cell body of an adult animal orientated with anterior to the left and dorsal to the top. Exposure times were identical for all images. Scale bar represents 20 µm for all images. (C) The SNT-1 levels were compared by Western blots (shown at top and quantified below) in four different mutant backgrounds as indicated. Note that the increased SNT-1 in <i>gv560</i> mutants (**, P<0.01) is reduced to wild type levels when the IDA-1 activity is removed in the <i>ida-1(ok409);pag-3(gv560)</i> double mutants. (D) Quantitative analysis of the images show in panel C confirmed that the signal intensity increases seen in the <i>gv560</i> mutant background are reduced to wild type levels in the <i>ida-1(ok409);pag-3(gv560)</i> double mutants (**, P<0.01). Note that the double mutant levels are not identical to <i>ida-1(ok409)</i>, suggesting there may be a small, IDA-1-independent effect of the <i>pag-3</i> mutation on serotonin.</p

Neurosecretory phenotypes of <i>pag-3(gv650)</i> are enhanced and are dependent on wild type IDA-1 activity.

<p>(A) An egg-laying assay was used to monitor neurosecretory behavior in wild type and mutant animals as described in the text. The average number eggs laid in <i>pag-3(gv560)</i> mutant animals is much higher than that in wild type animals (**, p<0.01), indicative of increased neurosecretion in the <i>pag-3</i> mutant. Both <i>ida-1(ok409)</i> single mutant and <i>ida-1(ok409);pag-3(gv560)</i> double mutants laid less eggs than wild type controls (*, p<0.05), demonstrating that <i>ida-1</i> is epistatic to <i>pag-3</i> for this phenotype. Data presented as the mean±SE (n = 10). (B) <i>pag-3(gv560)</i> mutants are hypersensitive to aldicarb. Shown are the aldicarb dose-response curves for wild type (N2), <i>pag-3(gv560)</i>, and <i>ida-1(ok409)</i> single mutants and <i>ida-1(ok409);pag-3(gv560)</i> double mutants. Increased neurosecretion makes animals hypersensitive to aldicarb (reduced survival), as is seen in the <i>pag-3(gv560)</i> mutant. The hypersensitivity of <i>pag-3(gv560)</i> animals is suppressed to below wild type levels in the <i>ida-1(ok409);pag-3(gv560)</i> double mutants. The one hundred percent value represents the number of progeny produced from a starting population of wild type L1 larvae over a 96 hr period in the absence of aldicarb. Curves are representative of duplicate experiments in three independent assays. (C) Wild type animals or <i>pag-3(gv560)</i> mutants alone have no dauer phenotype at 25°C compared to the <i>daf-28(sa191)</i> temperature sensitive allele that gives rise to ∼43% dauers at this temperature. The <i>pag-3(gv560)</i> mutation suppresses the <i>daf-28(sa191)</i> mutant dauer phenotype from ∼43% to ∼9% (p<0.01).</p

The <i>gv560</i> mutation is an allele of the gene <i>pag-3</i>, which encodes a zinc-finger transcription factor.

<p>(A) The genetic interval in which <i>gv560</i> was mapped genetically is shown with a 6.5-kb stretch of genomic DNA from the region shown below. The 11 exons of <i>pag-3</i> (boxes) were sequenced to identify the <i>gv560</i> allele as a C to T mutation resulting in a change in an evolutionarily conserved amino acid (S223F) in exon 7 as indicated by an arrow. (B) Trans heterozygous <i>gv560/pag-3(ls20)</i> animals showed the same phenotypes (IDA-1::GFP up regulation and extra neurons) as either the <i>gv560</i> or <i>pag-3(ls20)</i> homozygous single mutants (see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1000447#pgen-1000447-g001" target="_blank">Figure 1D</a>). (C) <i>pag-3(gv560)</i> phenotypes are rescued by a 6.5-kb PCR product that contains the putative promoter and all exons and introns of the wild type <i>pag-3</i> gene. In both panels B and C, the mid-section of an adult animal is shown with anterior to the left and dorsal at top, each imaged with identical exposure times. Scale bar represents 40 µm. (D) The percent of P9–P12 derived cells expressing the IDA-1::GFP transgene was compared in N2, <i>gv560</i>, and the rescued strain by counting 100 worms in each group, demonstrating nearly full rescue by the wild type <i>pag-3</i> transgene (**, P<0.01). (E) The <i>gv560</i> allele results in a S223F mutation in the fourth zinc-finger region. Several previously identified alleles of <i>pag-3</i> are also indicated. (F–H) Cell autonomous rescue of the GFP up regulation phenotype with a wild type encoding PAG-3 transgene. Representative ventral view images of P<i>_ida-1</i>IDA-1::GFP levels in VC4 and VC5 (anterior to the left) in <i>pag-3(gv560)</i> animals (F) and animals harboring a potentially rescuing transgene (G) using identical exposure conditions. Partial rescue was achieved by expressing the full-length <i>pag-3</i> cDNA under the <i>cat-1</i> promoter (−3 kb) from an extrachromosomal transgene. The P<i>_cat-1</i> and P<i>_ida-1</i> promoters used in these experiments have overlapping activity in VC4, VC5, and the HSNs, the only sites for which partial rescue was observed, demonstrating cell autonomy for PAG-3 activity. (H) Quantitative analysis of GFP levels in VC4 and VC5 neuron cell bodies from images of 15 animals for each strain using NIH ImageJ software. On average, animals harboring an extrachromosomal rescuing <i>pag-3</i> transgene had a ∼31% (P<0.01) reduction in the levels of IDA-1::GFP in VC4 and VC5 when compared to non-rescued mutants; ALA neuron GFP intensity was not altered in the rescued animals (not shown). Scale bar represents 40 µm.</p

mRNA Levels of Vesicle-related Genes Assayed by RT-PCR.

<p>Total RNA was prepared from young adult N2 or <i>pag-3(gv560)</i> animals.</p

Changes in IDA-1 and other dense core vesicle proteins in <i>pag-3(gv650)</i> mutants.

<p>(A) Transgenic IDA-1::GFP and endogenous IDA-1 levels in <i>gv560</i> mutants are elevated 5-fold and 8-fold, respectively, in <i>pag-3(gv650)</i> mutants compared to wild type animals as determined by Western blot analysis. Quantitative analysis is shown to the left and blot signals to the right. SNT-1 and SNB-1 in the <i>gv560</i> mutant are increased 2.9-fold and 1.8-fold, respectively, whereas RAB3 and UNC-31 levels remained unchanged. Tubulin levels served as the protein loading control. **, P<0.01, *, P<0.05. (B) The DCV cargo component serotonin is elevated 2.5-fold (P<0.01) in the HSN neurons of <i>gv560</i> mutants versus controls as shown by immunofluorescent staining of whole animals with an anti-serotonin antibody; exposure times and settings for both images was identical. As indicated in the diagram at top, the adult animals imaged are oriented with anterior to the left and dorsal to the top. Scale bar represents 20 µm.</p

Changes in the presynaptic region number of dense core vesicle in <i>pag-3</i> and <i>ida-1</i> mutants.

<p>Electron micrographs of unidentified ventral cord neurons showing the characteristic presynaptic density (black arrows) from wild type animals (A), <i>pag-3(gv560)</i> mutants (B), <i>ida-1(ok409)</i> mutants (C), and <i>ida-1(ok409);pag-3(gv560)</i> double mutants (D). Large dense core vesicle-like structures are indicated by white arrows in all panels. The scale bar represents 100 nm for all images. (E) The average number of DCVs per presynaptic region was quantified relative to wild type controls. The <i>pag-3(gv560)</i> mutants have an increased number of DCVs, whereas the <i>ida-1(ok409)</i> single mutants and <i>ida-1(ok409);pag-3(gv560)</i> double mutants have significantly decreased numbers (**p<0.01, *p<0.05). Note also that the DCVs in <i>pag-3(gv560)</i> mutants (panel B) are consistently smaller in size and often irregularly shaped. Error bars are one standard deviation.</p

Up-regulation of the IDA-1::GFP translational reporter gene in normal and ectopic neurons in <i>gv560</i> mutant animals.

<p>(A) Schematic diagram of the integrated IDA-1::GFP translational fusion reporter transgene in strain KM246 that was used for genetic screens. SP, signal peptide; TM, transmembrane domain; PTP, protein-tyrosine phosphatase-like domain. (B) Schematic diagram of a <i>C. elegans</i> hermaphrodite showing the positions of relevant cell bodies from the left lateral view with anterior to the left and dorsal to the top. (C) Ventral view of IDA-1::GFP transgene expression in VC4, VC5, VC6, PHC, and HSN neurons in wild type animals. (D) IDA-1::GFP levels in <i>gv560</i> mutant animals is markedly increased in VC4 and VC5 neurons and also is observed in four additional neurons (P9–P12 descendants) in the posterior region. (E) IDA-1::GFP in the cell body of the ALA neuron in the head of a wild type (left panel) and <i>gv560</i> mutant (right panel) animal; images were collected with identical exposure times. (F) P<i>_lin-11</i>GFP reporter expression in VC1-6 cells in a wild type animal. (G) P<i>_lin-11</i>GFP reporter expression confirmed that the additional posterior neurons observed in <i>gv560</i> mutants are derived from P9–P12. (H) IDA-1::GFP expression is observed in extra neurons derived from P9–P12 in <i>ced-3</i> mutant animals, but, it is not upregulated in VC or HSN neurons (only HSN(R) is visible in this focal plane). (I) Average intensities of IDA-1::GFP for five VC4 (left) or VC5 (right) neurons in each strain were quantitated and compared between wild type controls and <i>gv560</i> or <i>ced-3(n717)</i> mutants. **, P<0.01. All images are of adult animals oriented with anterior to the left and (where possible) dorsal towards the top. Scale bars indicate 40 µm.</p