Floral organs are specified by the combinatorial action of MADSdomain transcription factors, yet the mechanisms by which MADSdomain proteins activate or repress the expression of their target genes and the nature of their cofactors are still largely unknown. Here, we show using affinity purification and mass spectrometry that five major floral homeotic MADS-domain proteins (AP1, AP3, PI, AG, and SEP3) interact in floral tissues as proposed in the "floral quartet" model. In vitro studies confirmed a flexible composition of MADSdomain protein complexes depending on relative protein concentrations and DNA sequence. In situ bimolecular fluorescent complementation assays demonstrate that MADS-domain proteins interact during meristematic stages of flower development. By applying a targeted proteomics approach we were able to establish a MADS-domain protein interactome that strongly supports a mechanistic link between MADS-domain proteins and chromatin remodeling factors. Furthermore, members of other transcription factor families were identified as interaction partners of floral MADS-domain proteins suggesting various specific combinatorial modes of action.protein complex isolation | transcriptional regulation | chromatin activation | histone marks F lower development is one of the best understood developmental processes in plants. According to the classic ABC model (1), floral organs in the model plant species Arabidopsis are specified by the combinatorial activity of three functional gene classes. The A class genes represented by APETALA1 (AP1) and APETALA2 (AP2) specify sepal identity, and together with B class genes APETALA3 (AP3) and PISTILLATA (PI), they determine the identity of petals. The C class gene AGA-MOUS (AG) alone determines carpel identity and, together with B class genes, it specifies stamen identity. The ABC model was extended to the ABCE model, in which E class genes [SEPAL-LATA1-4 (SEP1-4)] are required for the specification of all four types of floral organs (2, 3). Based on genetic and yeast n-hybrid protein interaction data, it was later proposed in the "floral quartet model" that floral organs are specified by combinatorial protein interactions of ABCE-class MADS-domain transcription factors, which are thought to assemble into organ-specific quaternary protein complexes that bind to two CArG boxes, DNA consensus sequence CC[A/T] 6 GG, in regulatory regions of target genes (4, 5). E-class proteins have a special role in this model as major mediators of higher-order complex formation. Although interactions that were predicted in this model were further supported by additional in vitro DNA-binding assays and protoplast , formation and composition of these complexes in endogenous tissues remained unknown.Heterologous interaction studies in yeast and genetic data suggest recruitment of transcriptional coregulators such as SEUSS (SEU) and LEUNIG (LUG) by floral MADS-domain proteins (9). Ovule-specific MADS-domain protein complexes were found to form higher-order interactions with BELL1 (BEL1), a mem...

We report a compact fiber in-line Mach-Zehnder interferometer for refractive index sensing with high sensitivity and precise sensing location. One arm of the interferometer contains a microcavity formed by removing part of the fiber core near the core and cladding interface by femtosecond laser micromachining, and the other arm remains in line with the remaining part of the fiber core. Such a fiber in-line Mach-Zehnder interferometer exhibits an extremely high refractive-index-sensitivity of −9370 nm/RIU (refractive index unit) within the refractive index range between 1.31 and 1.335.

In this study, we used formalin-fixed paraffin-embedded melanocytic tumors to demonstrate reproducible alterations in microRNA expression in nevi compared with melanomas using a microarray platform. We validated those results in an independent set of nevi and melanomas by quantitative RT-PCR. miR-205 demonstrated a statistically significant, progressive diminution in expression from nevi to primary melanomas to metastatic melanomas. Enforced miR-205 expression in melanoma cells profoundly impairs cell motility and migration along with significantly decreased F-actin polymerization with only a modest reduction in cell proliferation. Using a xenograft model, melanoma cells overexpressing miR-205 exhibit a reduced migratory capacity compared with control tumor cells. Mechanistically, miR-205 overexpression results in decreased expression of the zinc-finger E-box binding homeobox 2 (ZEB2) mRNA and protein.This coincides with increased expression of E-cadherin mRNA and protein. Furthermore, re-introduction of ZEB2 into melanoma cells overexpressing miR-205 rescues these phenotypic effects and results in a restoration of cell migration and F-actin polymerization with a concomitant reduction in E-cadherin expression. Together, these results provide in vitro and in vivo evidence for miR-205 as a critical suppressor of melanoma cell migration.

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With the advantages of completely controlling the phase, amplitude, and polarization in subwavelength range, metalenses have drawn intensive attentions in high resolution two-photon micro-endoscopic fluorescence imaging system. However, chromatic dispersion and severe scattering of biological tissue significantly reduce excitation-collection efficiency in the traditional two-photon imaging system based on traditional metalenses designed in the air background. Here, an excitation and emission dual-wavelength confocal and polarization-insensitive metalens designed in the biological tissue environment was proposed by adopting the composite embedding structure and spatial multiplexing approach. The metalens with numerical aperture (NA) of 0.895 can focus the excitation (915 nm) and emission (510 nm) beams to the same focal spot in the mouse cortex. According to the theoretical simulation of two-photon fluorescence imaging, the lateral resolution of the collected fluorescent spots via the proposed metalens can be up to 0.42 µm. Compared to the metalens designed in the air environment, the collection efficiency of fluorescent spot is improved from 5.92% to 14.60%. Our investigation has opened a new window of high resolution and minimally invasive imaging in deep regions of biological tissues.

We introduce a femtosecond-laser-based technique for selective opening of airholes in photonic crystal fibers (PCFs). With this technique, selective filling and inflation of the airholes in the PCF cladding are demonstrated. The technique may find important applications in tailoring or altering PCF characteristics and make it possible to seamlessly integrate various components/functions into PCFs. © 2010 Optical Society of America OCIS codes: 060.2310, 060.2340, 060.2400.The photonic crystal fiber (PCF) with a periodic array of airholes running along its length has attracted significant interest recently [1,2]. The precise arrangement of airholes and their index profiles throughout the cladding region allow various types of PCFs with novel properties to be designed. Endlessly single-mode operation, lightguidance in hollow air-core, and very high nonlinearity and birefringence are a few of the novel properties of PCFs that may not be achieved with conventional singlemode fibers (SMFs) [3,4]. Apart from the high level of flexibility in the PCF fabrication process, novel functionality may be added to PCFs by postprocessing [5][6][7][8].Techniques for postprocessing PCFs include tapering and inscription of periodic structures that are widely adopted for conventional fibers and selective filling or pressurization of airholes, which is unique to PCFs. Examples of PCF postprocessing include selective filling of airholes with an index tunable polymer to realize birefringence tunability [5], inflating/deflating airholes to reduce splice loss and to achieve in-fiber mode conversion [6,7], and infiltrating submicrometer gold into a selected hole of a polarization maintaining PCF to achieve polarizationand wavelength-dependent transmission [8]. All these examples rely on the selective opening or closing of airholes within the cladding region. We previously demonstrated selective filling of PCFs by using a conventional fusion splicer [9], but it lacks the freedom to choose arbitrary airholes for filling. In this Letter, we report a technique for selective opening of airholes and demonstrate the selective filling and inflation of arbitrary holes in the PCF cladding. Our approach starts by sealing all the airholes of a PCF by a thin layer of silica and then drilling individual holes through the layer by a femtosecond IR laser (fs-laser). With reference to Fig. 1(a), the PCF is first spliced to a conventional SMF by a fusion splicer. The SMF is then cleaved at a location about 30 μm from the splicing point. The splicing parameters are adjusted so that airhole deformation during splicing is minimized, while the splice is reasonably strong to survive the cleaving [10]. The thin layer of SMF seals all the airholes, but the end facet of the PCF beneath the thin silica layer can be clearly viewed under a microscope, allowing an individual airhole to be selected and located. Figure 1(b) shows the microscopic view of the end facet of a large-mode-area PCF [LMA-10, NKT Photonics A/S, scanning electron micrograph (SEM) photograph is sho...

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We report Q-switched pulse operation of holmium (Ho(3+))-doped ZrF(4)-BaF(2)-LaF(3)-AlF(3)-NaF (ZBLAN) at ∼1190  nm in an all-fiber ring laser by using a fiber-optic graphene saturable absorber, which was fabricated by depositing graphene onto the flat surface of a side-polished D-shaped fiber. Stable Q-switched operation was established at a pump power of 180 mW with a repetition rate of 24 kHz and pulse width of 5.7 μs. When the pump power was increased to 1125 mW, 0.44 μJ Q-switched pulses with a repetition rate of 111 kHz and a pulse width of 0.8 μs were generated.