In a genetic screen in a drnl-2 background, we isolated a loss-offunction allele in miR319a (miR319a 129 ). Previously, miR319a has been postulated to play a role in leaf development based on the dramatic curled-leaf phenotype of plants that ectopically express miR319a (jaw-D). miR319a 129 mutants exhibit defects in petal and stamen development; petals are narrow and short, and stamens exhibit defects in anther development. The miR319a 129 loss-of-function allele contains a single-base change in the middle of the encoded miRNA, which reduces the ability of miR319a to recognize targets. Analysis of the expression patterns of the three members of the miR319 gene family (miR319a, miR319b, and miR319c) indicates that these genes have largely non-overlapping expression patterns suggesting that these genes have distinct developmental functions. miR319a functions by regulating the TCP transcription factors TCP2, TCP3, TCP4, TCP10, and TCP24; the level of RNA expression of these TCP genes is down-regulated in jaw-D and elevated in miR319a 129 . Several lines of evidence demonstrate that TCP4 is a key target of miR319a. First, the tcp4 soj6 mutant, which contains a mutation in the TCP4 miRNAbinding site complementary to the miR319a 129 mutation, suppresses the flower phenotype of miR319a 129 . Second, expression of wild-type TCP4 in petals and stamens (i.e., AP3:TCP4) has no effect on flower development; by contrast, a miRNA-resistant version of TCP4, when expressed in petals and stamens (i.e., pAP3:mTCP4) causes these organs not to develop. Surprisingly, when AP3:TCP4 is present in a miR319a 129 background, petal and stamen development is severely disrupted, suggesting that proper regulation by miR319a of TCP4 is critical in these floral organs.DRNL ͉ flower development ͉ forward genetics ͉ microRNA ͉ stamen M icroRNAs (miRNAs) are 21-24 nucleotide regulatory RNAs that function in diverse aspects of plant biology (1) such as biotic and abiotic stress responses (2), metabolism (3), hormone signaling (4), transcription (5), development (6), and the regulation of miRNA machinery itself (7,8). Most studies of plant miRNAs focus on alleles that ectopically express the miRNA. In miRNA overexpression lines, the RNA levels of target genes are downregulated resulting in a phenotype that mimics the loss-of-function phenotypes of miRNA target mutants (9, 10). Loss-of-function alleles in miRNA genes are rare because most often miRNAs are redundantly encoded in plant genomes. Thus, mutation of a single miRNA gene usually does not result in a mutant phenotype. In the few miRNA loss-of-function mutants that are available (5,6,11,12), the RNA levels of target genes are elevated, which is expected if the miRNA can no longer function to degrade target mRNAs. miR319a was initially characterized based on the dramatic leaf phenotype that results from overexpression of miR319a, as in the jaw-D allele that results in a jagged and wavy (jaw) leaf-phenotype (13). The best-characterized targets of miR319 are a subset of TCP transcription factors...

Environmental context. Levels of atmospheric dimethylsulfide (DMS) and its oxidation products are reputed to affect the microphysics of clouds and the amount of incoming solar radiation to the ocean. Studies of DMS and its precursor compound dimethylsulfoniopropionate (DMSP) at two inshore fringing coral reefs in the Great Barrier Reef highlight pronounced seasonal, diurnal and tidal variation of these compounds, with dissolved DMS and DMSP significantly correlated with sea surface temperatures (SSTs) up to 30°C. During a coral bleaching episode at one of the reef sites, dissolved DMS concentrations decreased when SSTs exceeded 30°C, a result replicated in chamber experiments with staghorn coral. The results raise interesting questions on the role of these organosulfur substances in corals and whether DMS emissions from coral reefs could have an effect on regional climate in the Great Barrier Reef. Abstract. A study of dissolved dimethylsulfide (DMSw), dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp), and atmospheric dimethylsulfide (DMSa) was carried out at two inshore fringing coral reefs (Orpheus Island and Magnetic Island) in the Great Barrier Reef (GBR) to investigate the variation of these organosulfur substances with season, sea surface temperature, tides, and time of day. Highest concentrations of these organosulfur substances occurred in the summer months at both reefs, with lowest concentrations occurring during winter, suggesting a biological source of these compounds from the reef flats. At the Orpheus Island reef, where more measurements were made, DMSw and DMSPd were significantly correlated with tidal height during the flooding tide over the reef (r = 0.37, P < 0.05; r = 0.58, P < 0.01 respectively), and elevated DMSw and DMSa concentrations generally occurred in the daylight hours, possibly reflecting photosynthetic production of DMSw from the reef flats. Chamber experiments with the staghorn coral Acropora formosa confirmed that corals produce DMSw in the day. DMSw (r = 0.43, P < 0.001) and DMSPd (r = 0.59, P < 0.001) were significantly positively correlated with sea surface temperatures (SST) at the Orpheus Island reef. During severe coral bleaching at the eutrophic Magnetic Island reef in the summer, DMSw concentrations decreased at SSTs greater than 30°C, suggesting that reef production of DMSw decreases during elevated SSTs. This was later confirmed in chamber experiments with Acropora formosa, which showed that when this coral was exposed to temperatures at its bleaching threshold (31°C), decreased production of DMSw occurred. These results suggest that DMS and DMSP in coral zooxanthellae may be functioning as antioxidants, but further experiments are needed to substantiate this.

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Thermal tolerance tests on Acropora millepora, a common Indo-Pacific hard coral, have shown that adult corals can acquire increased thermal tolerance by shuffling existing type C to type D Symbiodinium zooxanthellae when subjected to increased seawater temperatures. We report here dimethylsulphoniopropionate (DMSP) concentrations in A. millepora and examine links between DMSP concentrations, zooxanthellae clade, and bleaching tolerance. DMSP analysis on native and transplanted corals from three locations in the Great Barrier Reef indicated that the lower thermal tolerance in type C zooxanthellae coincided with variable DMSP concentrations, whilst the more thermal tolerant type D zooxanthellae had more stable areal DMSP concentrations as seawater temperatures increased. Our results suggest this increased thermal tolerance in type D zooxanthellae may reflect the ability of these coral symbionts to conserve their antioxidant DMSP levels to relatively constant concentrations, enabling the coral to overcome the build-up of oxygen free radicals in the cytoplasm of A. millepora. A conceptual diagram illustrates how the antioxidants DMS (P) participate in the bleaching process by scavenging oxygen free radicals and form DMSO, thus moderating coral bleaching and increasing thermotolerance.

Meta-analyses report larger amygdala in subjects with bipolar disorder compared to schizophrenia. However, few studies have compared the size of amygdala in psychotic bipolar disorder with schizophrenia. Here we examine size of amygdala in a sample of 36 patients with psychotic bipolar disorder, 31 patients with schizophrenia and 27 healthy comparison subjects. Patients with schizophrenia had smaller amygdala compared with patients with psychotic bipolar disorder (p=0.014). These results suggest that change in volume of amygdala may represent a morphologic feature distinguishing psychotic bipolar disorder from schizophrenia.