The microtubule regulator EFA-6 forms spatially restricted cortical foci dependent on its intrinsically disordered region and interactions with tubulins.

Microtubules (MTs) are dynamic components of the cytoskeleton and play essential roles in morphogenesis and maintenance of tissue and cell integrity. Despite recent advances in understanding MT ultrastructure, organization, and growth control, how cells regulate MT organization at the cell cortex remains poorly understood. The EFA-6/EFA6 proteins are recently identified membrane-associated proteins that inhibit cortical MT dynamics. Here, combining visualization of endogenously tagged C. elegans EFA-6 with genetic screening, we uncovered tubulin-dependent regulation of EFA-6 patterning. In the mature epidermal epithelium, EFA-6 forms punctate foci in specific regions of the apical cortex, dependent on its intrinsically disordered region (IDR). We further show the EFA-6 IDR is sufficient to form biomolecular condensates in vitro. In screens for mutants with altered GFP::EFA-6 localization, we identified a novel gain-of-function (gf) mutation in an α-tubulin tba-1 that induces ectopic EFA-6 foci in multiple cell types. tba-1(gf) animals exhibit temperature-sensitive embryonic lethality, which is partially suppressed by efa-6(lf), indicating the interaction between tubulins and EFA-6 is important for normal development. TBA-1(gf) shows reduced incorporation into filamentous MTs but has otherwise mild effects on cellular MT organization. The ability of TBA-1(gf) to trigger ectopic EFA-6 foci formation requires ß-tubulin TBB-2 and the chaperon EVL-20/Arl2. The tba-1(gf)-induced EFA-6 foci display slower turnover, contain the MT-associated protein TAC-1/TACC, and require the EFA-6 MTED. Our results reveal a novel crosstalk between cellular tubulins and cortical MT regulators in vivo.

Polarization- and Gate-Tunable Optoelectronic Reverse in 2D Semimetal/Semiconductor Photovoltaic Heterostructure.

Polarimetric photodetector can acquire higher resolution and more surface information of imaging targets in complex environments due to the identification of light polarization. To date, the existing technologies yet sustain the poor polarization sensitivity (<10), far from market application requirement. Here, the photovoltaic detectors with polarization- and gate-tunable optoelectronic reverse phenomenon are developed based on semimetal 1T'-MoTe2 and ambipolar WSe2 . The device exhibits gate-tunable reverse in rectifying and photovoltaic characters due to the directional inversion of energy band, yielding a wide range of current rectification ratio from 10-2 to 103 and a clear object imaging with 100 × 100 pixels. Acting as a polarimetric photodetector, the polarization ratio (PR) value can reach a steady state value of ≈30, which is compelling among the state-of-the-art 2D-based polarized detectors. The sign reversal of polarization-sensitive photocurrent by varying the light polarization angles is also observed, that can enable the PR value with a potential to cover possible numbers (1→+∞/-∞→-1). This work develops a photovoltaic detector with polarization- and gate-tunable optoelectronic reverse phenomenon, making a significant progress in polarimetric imaging and multifunction integration applications.

Maternal Ribosomes Are Sufficient for Tissue Diversification during Embryonic Development in C. elegans.

Caenorhabditis elegans provides an amenable system to explore whether newly composed ribosomes are required to progress through development. Despite the complex pattern of tissues that are formed during embryonic development, we found that null homozygotes lacking any of the five different ribosomal proteins (RPs) can produce fully functional first-stage larvae, with similar developmental competence seen upon complete deletion of the multi-copy ribosomal RNA locus. These animals, relying on maternal but not zygotic contribution of ribosomal components, are capable of completing embryogenesis. In the absence of new ribosomal components, the resulting animals are arrested before progression from the first larval stage and fail in two assays for postembryonic plasticity of neuronal structure. Mosaic analyses of larvae that are a mixture of ribosome-competent and non-competent cells suggest a global regulatory mechanism in which ribosomal insufficiency in a subset of cells triggers organism-wide growth arrest.

Effects of Spatial Patch Arrangement and Scale of Covarying Resources on Growth and Intraspecific Competition of a Clonal Plant.

Spatial heterogeneity in two co-variable resources such as light and water availability is common and can affect the growth of clonal plants. Several studies have tested effects of spatial heterogeneity in the supply of a single resource on competitive interactions of plants, but none has examined those of heterogeneous distribution of two co-variable resources. In a greenhouse experiment, we grew one (without intraspecific competition) or nine isolated ramets (with competition) of a rhizomatous herb Iris japonica under a homogeneous environment and four heterogeneous environments differing in patch arrangement (reciprocal and parallel patchiness of light and soil water) and patch scale (large and small patches of light and water). Intraspecific competition significantly decreased the growth of I. japonica, but at the whole container level there were no significant interaction effects of competition by spatial heterogeneity or significant effect of heterogeneity on competitive intensity. Irrespective of competition, the growth of I. japonica in the high and the low water patches did not differ significantly in the homogeneous treatments, but it was significantly larger in the high than in the low water patches in the heterogeneous treatments with large patches. For the heterogeneous treatments with small patches, the growth of I. japonica was significantly larger in the high than in the low water patches in the presence of competition, but such an effect was not significant in the absence of competition. Furthermore, patch arrangement and patch scale significantly affected competitive intensity at the patch level. Therefore, spatial heterogeneity in light and water supply can alter intraspecific competition at the patch level and such effects depend on patch arrangement and patch scale.

Effects of patch contrast and arrangement on benefits of clonal integration in a rhizomatous clonal plant.

The availabilities of light and soil water resources usually spatially co-vary in natural habitats, and the spatial pattern of such co-variation may affect the benefits of physiological integration between connected ramets of clonal plants. In a greenhouse experiment, we grew connected or disconnected ramet pairs [consisting of a proximal (relatively old) and a distal (relative young) ramet] of a rhizomatous herb Iris japonica in four heterogeneous environments differing in patch arrangement (reciprocal vs. parallel patchiness of light and soil water) and patch contrast (high vs. low contrast of light and water). Biomass of the proximal part, distal part and clonal fragment of I. japonica were all significantly greater in the intact than in the severed treatment, in the parallel than in the reciprocal patchiness treatment and in the high than in the low contrast treatment, but the effect of severing the connection between ramet pairs did not depend on patch arrangement or contrast. Severing the connection decreased number of ramets of the distal part and the clonal fragment in the parallel patchiness arrangement, but not in the reciprocal patchiness arrangement. Therefore, the spatial arrangement of resource patches can alter the effects of clonal integration on asexual reproduction in I. japonica.