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Distal appendages (DAPs) are nanoscale, pinwheel-like structures protruding from the distal end of the centriole that mediate membrane docking during ciliogenesis, marking the cilia base around the ciliary gate. Here we determine a super-resolved multiplex of 16 centriole-distal-end components. Surprisingly, rather than pinwheels, intact DAPs exhibit a cone-shaped architecture with components filling the space between each pinwheel blade, a new structural element we term the distal appendage matrix (DAM). Specifically, CEP83, CEP89, SCLT1, and CEP164 form the backbone of pinwheel blades, with CEP83 confined at the root and CEP164 extending to the tip near the membrane-docking site. By contrast, FBF1 marks the distal end of the DAM near the ciliary membrane. Strikingly, unlike CEP164, which is essential for ciliogenesis, FBF1 is required for ciliary gating of transmembrane proteins, revealing DAPs as an essential component of the ciliary gate. Our findings redefine both the structure and function of DAPs. Distal appendages (DAPs) at the cilia base mediate membrane docking during ciliogenesis. Here the authors use super-resolution microscopy to map 16 centriole distal end components, revealing the structure of the backbone of the DAP, as well as a previously undescribed distal appendage matrix.

Subdistal appendages (sDAPs) are centriolar elements that are observed proximal to the distal appendages (DAPs) in vertebrates. Despite the obvious presence of sDAPs, structural and functional understanding of them remains elusive. Here, by combining super-resolved localization analysis and CRISPR-Cas9 genetic perturbation, we find that although DAPs and sDAPs are primarily responsible for distinct functions in ciliogenesis and microtubule anchoring, respectively, the presence of one element actually affects the positioning of the other. Specifically, we find dual layers of both ODF2 and CEP89, where their localizations are differentially regulated by DAP and sDAP integrity. DAP depletion relaxes longitudinal occupancy of sDAP protein ninein to cover the DAP region, implying a role of DAPs in sDAP positioning. Removing sDAPs alter the distal border of centrosomal γ-tubulins, illustrating a new role of sDAPs. Together, our results provide an architectural framework for sDAPs that sheds light on functional understanding, surprisingly revealing coupling between DAPs and sDAPs.

The molecular basis of plant osmosensing remains unknown. Arabidopsis (Arabidopsis thaliana) Histidine Kinase1 (AHK1) can complement the osmosensitivity of yeast (Saccharomyces cerevisiae) osmosensor mutants lacking Synthetic Lethal of N-end rulel and SH3-containing Osmosensor and has been proposed to act as a plant osmosensor. We found that ahk1 mutants in either the Arabidopsis Nossen-0 or Columbia-0 background had increased stomatal density and stomatal index consistent with greater transpirational water loss. However, the growth of ahk1 mutants was not more sensitive to controlled moderate low water potential (ψ w ) or to salt stress. Also, ahk1 mutants had increased, rather than reduced, solute accumulation across a range of low ψ w severities. ahk1 mutants had reduced low ψ w induction of ∆¹-Pyrroline-5-Carboxylate Synthetasel (P5CS1) and 9-cis-Epoxycarotenoid Dioxygenase3, which encode rate-limiting enzymes in proline and abscisic acid (ABA) synthesis, respectively. However, neither Pro nor ABA accumulation was reduced in ahk1 mutants at low ψ w . P5CS1 protein level was not reduced in ahk1 mutants. This indicated that proline accumulation was regulated in part by posttranscriptional control of P5CS1 that was not affected by AHK1. Expression of AHK1 itself was reduced by low ψ w , in contrast to previous reports. These results define a role of AHK1 in controlling stomatal density and the transcription of stress-responsive genes. These phenotypes may be mediated in part by reduced ABA sensitivity. More rapid transpiration and water depletion can also explain the previously reported sensitivity of ahk1 to uncontrolled soil drying. The unimpaired growth, ABA, proline, and solute accumulation of ahk1 mutants at low ψ w suggest that AHK1 may not be the main plant osmosensor required for low ψ w tolerance.

Vertebrate centrioles normally propagate through duplication, but in the absence of preexisting centrioles, de novo synthesis can occur. Consistently, centriole formation is thought to strictly rely on self-assembly, involving self-oligomerization of the centriolar protein SAS-6. Here, through reconstitution of de novo synthesis in human cells, we surprisingly found that normal looking centrioles capable of duplication and ciliation can arise in the absence of SAS-6 self-oligomerization. Moreover, whereas canonically duplicated centrioles always form correctly, de novo centrioles are prone to structural errors, even in the presence of SAS-6 self-oligomerization. These results indicate that centriole biogenesis does not strictly depend on SAS-6 self-assembly, and may require preexisting centrioles to ensure structural accuracy, fundamentally deviating from the current paradigm. Cells pass on their characteristics or “traits” to new generations in the form of DNA molecules. DNA provides the instructions to make proteins, which may then assemble into larger structures without using any external templates in a process called self-assembly. However, when a cell divides, DNA is not the only element that is passed on to the daughter cells; many large protein structures that have assembled in mother cells are also divided between the daughter cells. The daughter cells may then produce extra copies of these protein structures, but it is not known whether the pre-existing structures are involved in this process. Centrioles are complex structures made of proteins and play a crucial role in cell division. One of the main components of centrioles is a protein called SAS-6. Recent studies have shown that SAS-6 molecules can bind to each other to form “oligomers”. This process, which is called self-oligomerization, has been proposed to drive the formation of centrioles. Now, Wang et al. examine whether centrioles can form properly in cells when no other centrioles are present. The experiments show that centrioles can indeed form, but they are prone to structural errors. In contrast, centrioles that form in the presence of older centrioles are essentially free of errors. The experiments used human eye cells that were missing the gene that encodes SAS-6. These cells could not make centrioles, but when SAS-6 was re-introduced into these cells, new centrioles formed. Unexpectedly, re-introducing a mutant form of SAS-6 that cannot form oligomers into the cells still allowed new centrioles to form, which shows that self-oligomerization of SAS-6 is not essential for the assembly of centrioles. Together, Wang et al.’s findings challenge the idea that SAS-6 self-oligomerization is involved in the formation of centrioles, and suggest that preexisting centrioles may help to minimize errors in the formation of new centrioles.

Helper-component proteinase (HC-Pro), encoded by potyviruses, function as viral suppressors of RNA silencing (VSRs). Despite their conserved role, HC-Pros share approximately 40% similarity, implying potential differences in VSR efficiency, particularly in their ability to inhibit HEN1 methyltransferase activity. This study investigated the inhibitory potential of HC-Pros from different potyviruses in transgenic plants. P1/HC-Pro from turnip mosaic virus (P1/HC-Pro Tu ) exhibited the most potent inhibition of HEN1, followed by P1/HC-Pro from zucchini yellow mosaic virus (P1/HC-Pro Zy ), while P1/HC-Pro from tobacco etch virus (P1/HC-Pro Te ) showed the weakest inhibitory effect. These differential effectual effects corresponded to variations in unmethylated microRNAs (unMet-miRNAs) accumulation across the transgenic lines. Fluorescence resonance energy transfer (FRET) analysis indicated that HC-Pro Tu recruits HEN1 and ATG8a to HC-Pro bodies (H-bodies) and indirectly associates with AGO1, potentially influencing the assembly of the RNA-induced silencing complex (RISC) and leading to the accumulation of free-form miRNA duplexes. The ability of HC-Pro Tu to sequester HEN1 and AGO1 in H-bodies may, therefore, modulate miRNA loading. This observation aligns with the finding that P1/HC-Pro Tu plants harbored approximately 50% unMet-miRNAs and exhibited the lowest AGO1 levels, suggesting a positive correlation between HEN1 inhibition and autophagic degradation of AGO1. Interestingly, unMet-miRNAs are absent in the AGO1 of P1/HC-Pro Tu plants but reappeared in P1/HC-Pro Tu /hen1-8/heso1-1 plants, accompanied by signs of AGO1 recovery. These findings highlight the functional diversity of HC-Pro VSRs and provide new insights into their differential effects on miRNA methylation, RISC assembly, and the regulation of RNA silencing pathways. This study demonstrated that different types of HC-Pros from potyviruses exhibit varying capacities to inhibit HEN1. This results in distinct levels of autophagic AGO1 degradation, which in turn leads to differences in RNA silencing suppression efficiency.

Background Endolithic microbes in coral skeletons are known to be a nutrient source for the coral host. In addition to aerobic endolithic algae and Cyanobacteria , which are usually described in the various corals and form a green layer beneath coral tissues, the anaerobic photoautotrophic green sulfur bacteria (GSB) Prosthecochloris is dominant in the skeleton of Isopora palifera . However, due to inherent challenges in studying anaerobic microbes in coral skeleton, the reason for its niche preference and function are largely unknown. Results This study characterized a diverse and dynamic community of endolithic microbes shaped by the availability of light and oxygen. In addition, anaerobic bacteria isolated from the coral skeleton were cultured for the first time to experimentally clarify the role of these GSB. This characterization includes GSB’s abundance, genetic and genomic profiles, organelle structure, and specific metabolic functions and activity. Our results explain the advantages endolithic GSB receive from living in coral skeletons, the potential metabolic role of a clade of coral-associated Prosthecochloris (CAP) in the skeleton, and the nitrogen fixation ability of CAP. Conclusion We suggest that the endolithic microbial community in coral skeletons is diverse and dynamic and that light and oxygen are two crucial factors for shaping it. This study is the first to demonstrate the ability of nitrogen uptake by specific coral-associated endolithic bacteria and shed light on the role of endolithic bacteria in coral skeletons.

Lung cancer ranks among the most common malignancies, and is the leading cause of cancer-related mortality worldwide. Chemotherapy for lung cancer can be made more specific to tumor cells, and less toxic to normal tissues, through the use of ligand-mediated drug delivery systems. In this study, we investigated the targeting mechanism of the ligand-mediated drug delivery system using a peptide, SP5-2, which specifically binds to non-small cell lung cancer (NSCLC) cells. Conjugation of SP5-2 to liposomes enhanced the amount of drug delivered directly into NSCLC cells, through receptor-mediated endocytosis. Functional SP5-2 improved the therapeutic index of Lipo-Dox by enhancing therapeutic efficacy, reducing side effects, and increasing the survival rate of tumor-bearing mice in syngenic, metastatic and orthotopic animal models. Accumulation of SP5-2-conjugated liposomal doxorubicin (SP5-2-LD) in tumor tissues was 11.2-fold higher than that of free doxorubicin, and the area under the concentration-time curve (AUC0-72 hours) was increased 159.2-fold. Furthermore, the experiment of bioavailability was assessed to confirm that SP5-2 elevates the uptake of the liposomal drugs by the tumor cells in vivo. In conclusion, the use of SP5-2-conjugated liposomes enhances pharmacokinetic properties, improves efficacy and safety profiles, and allows for controlled biodistribution and drug release.

orchids have a spectacular floral morphology with a highly evolved lip that offers a landing platform for pollinators. The typical morphological orchid lip features are essential for the special pollination mechanism of flowers. Previously, we found that in the lip, a member of the AP2/EREBP protein family was highly expressed. Here, we further confirmed its high expression and characterized its function during lip development. Phylogenetic analysis showed that AP2/EREBP belongs to the Va2 subgroup of ERF transcription factors. We named it PeERF1. We found that was only expressed at stage 5, as flowers opened. This coincided with both thickening of the cuticle and development of nanoridges. We performed knockdown expression of using CymMV-based virus-induced gene silencing in either the conserved domain, producing -silenced plants, or the specific domain, producing silenced plants. Using cryo-SEM, we found that the number of nanoridges was reduced only in the -silenced group. This change was found on both the abaxial and adaxial surfaces of the central lip lobe. Expression of was reduced significantly in -silenced plants. In cutin biosynthesis genes, expression of both and was significantly decreased in both groups. The expression of was reduced significantly only in the -silenced plants. Although expression was reduced in both silenced plants, but to a lesser degree. The expression of was significantly reduced in the petal-like lip of a big-lip variant. and in the lip were also reduced, but . Furthermore, heterologous overexpression of in the genus produced leaves that were shiny on the adaxial surface. Taken together, our results show that in orchids PeERF1 plays an important role in formation of nanoridges during lip epidermis development.

A novel chitosan immobilization technique that entraps photocatalyst and microbes was developed and applied to decompose decabromodiphenyl ether (BDE-209) in a clay slurry microcosm. The optimized conditions for immobilization were obtained by mixing 1.2% (w/v) chitosan dissolved in 1% (v/v) acetic acid with nano-TiO2 particles and the BDE-209-degrading bacterial mixed culture. This aqueous mixture was injected into 1% (w/v) water solution containing sodium tripolyphosphate to form spherical immobilized beads. The surface of the immobilized beads was reinforced by 0.25% (v/v) glutaraldehyde cross-linking. These beads had enough mechanical strength during BDE-209 degradation to maintain their shape in the system at a stirring rate of 200-rpm, while undergoing continuous 365 nm UVA irradiation. This novel TiO2-Yi-Li immobilized chitosan beads system allowed a successful simultaneous integration of photolysis, photocatalysis and biodegradation to remove BDE-209. The remaining percentage of BDE-209 was 41% after 70 days of degradation using this system. The dominant bacteria in the BDE-209-degrading bacterial mixed culture during remediation were Chitinophaga spp., Methyloversatilis spp., Terrimonas spp. and Pseudomonas spp. These bacteria tolerated the long-term UVA irradiation and high-level free radicals present, while utilizing BDE-209 as their primary carbon resource. This new method has great potential for the treatment of a range of pollutants.

In the early development of Trochodendron aralioides (Trochodendraceae) inflorescences lateral flowers are initiated after the appearance of the floral pherophylls (subtending bracts). The terminal flower is preceded by metaxyphylls and is initiated earlier than the uppermost lateral flowers of the botryoid inflorescence. Small scales (interpreted as rudimentary perianth organs) precede the stamens. These scales are more distinct in the terminal flower than in the lateral flowers. In the radially symmetrical terminal flower, small scales (or metaxyphylls) and stamens are initiated in a spiral during early development. At anthesis, stamen phyllotaxis appears irregular or approximately whorled as a result of the rapid elongation and irregular slight curvature of the stamen filaments which distorts the originally regular pattern. Finally, the numerous carpels arise simultaneously in a single whorl. It takes about 9 months for flowers to develop and the 2-year reproductive cycle of T. aralioides is typical of many trees. The floral development of T. aralioides is compared with that of other basal eudicots. The bottle-shaped, unicellular stigmatic papillae and long, decurrent stigma of basally united carpels are similar to those of the Buxales, suggesting a close relationship.