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Soybean cyst nematodes (Heterodera glycines) produce secreted effector proteins that function as peptide mimics of plant CLAVATA3/ESR (CLE)-like peptides probably involved in the developmental reprogramming of root cells to form specialized feeding cells called syncytia. The site of action and mechanism of delivery of CLE effectors to host plant cells by the nematode, however, have not been established. In this study, immunologic, genetic and biochemical approaches were used to reveal the localization and site of action of H. glycines-secreted CLE proteins in planta. We present evidence indicating that the nematode CLE propeptides are delivered to the cytoplasm of syncytial cells, but ultimately function in the apoplast, consistent with their proposed role as ligand mimics of plant CLE peptides. We determined that the nematode 12-amino-acid CLE motif peptide is not sufficient for biological activity in vivo, pointing to an important role for sequences upstream of the CLE motif in function. Genetic and biochemical analysis confirmed the requirement of the variable domain in planta for host-specific recognition and revealed a novel role in trafficking cytoplasmically delivered CLEs to the apoplast in order to function as ligand mimics.

Allopolyploids are organisms possessing more than two complete sets of chromosomes from two or more species and are frequently more vigorous than their progenitors. To address the question why allopolyploids display hybrid vigor, we compared the natural allopolyploid Arabidopsis suecica to its progenitor species Arabidopsis thaliana and Arabidopsis arenosa. We measured chlorophyll content, CO₂ assimilation, and carbohydrate production under varying light conditions and found that the allopolyploid assimilates more CO₂ per unit chlorophyll than either of the two progenitor species in high intensity light. The increased carbon assimilation corresponds with greater starch accumulation, but only in strong light, suggesting that the strength of hybrid vigor is dependent on environmental conditions. In weaker light A. suecica tends to produce as much primary metabolites as the better progenitor. We found that gene expression of LIMIT DEXTRINASE1, a debranching enzyme that cleaves branch points within starch molecules, is at the same level in the allopolyploid as in the maternal progenitor A. thaliana and significantly more expressed than in the paternal progenitor A. arenosa. However, expression differences of β-amylases and GLUCAN-WATER DIKINASE1 were not statistically significantly elevated in the allopolyploid over progenitor expression levels. In contrast to allopolyploids, autopolyploid A. thaliana showed the same photosynthetic rate as diploids, indicating that polyploidization alone is likely not the reason for enhanced vigor in the allopolyploid. Taken together, our data suggest that the magnitude of heterosis in A. suecica is environmentally regulated, arises from more efficient photosynthesis, and, under specific conditions, leads to greater starch accumulation than in its progenitor species.

SCF-type E3 ubiquitin ligases provide specificity to numerous selective protein degradation events in plants, including those that enable survival under environmental stress. SCF complexes use F-box (FBX) proteins as interchangeable substrate adaptors to recruit protein targets for ubiquitylation. FBX proteins almost universally have structure with two domains: A conserved N-terminal F-box domain interacts with a SKP protein and connects the FBX protein to the core SCF complex, while a C-terminal domain interacts with the protein target and facilitates recruitment. The F-BOX STRESS INDUCED (FBS) subfamily of plant FBX proteins has an atypical structure, however, with a centrally located F-box domain and additional conserved regions at both the N- and C-termini. FBS proteins have been linked to environmental stress networks, but no ubiquitylation target(s) or biological function has been established for this subfamily. We have identified two WD40 repeat-like proteins in Arabidopsis that are highly conserved in plants and interact with FBS proteins, which we have named FBS INTERACTING PROTEINs (FBIPs). FBIPs interact exclusively with the N-terminus of FBS proteins, and this interaction occurs in the nucleus. FBS1 destabilizes FBIP1, consistent with FBIPs being ubiquitylation targets SCFFBS1 complexes. This work indicates that FBS proteins may function in stress-responsive nuclear events, and it identifies two WD40 repeat-like proteins as new tools with which to probe how an atypical SCF complex, SCFFBS, functions via FBX protein N-terminal interaction events.

Background: Little is known about the potential adverse hepatic effects of HMG-CoA reductase inhibitors (‘statins’) in patients with existing liver disease; therefore, we examined the risk of liver toxicity with lovastatin exposure in these patients. Methods: A retrospective cohort study was performed using data from a large integrated health plan in Northern California, USA. Patients with laboratory or clinical evidence of liver disease were identified and their exposure to lovastatin was determined. The primary outcome was a pattern of liver-test abnormalities associated with a poor prognosis among patients with drug-induced liver disease, based on Hy’s Rule. Secondary outcomes included liver injury (defined as moderate or severe, depending on the degree of ALT level elevations) or the development of either clinical cirrhosis or liver failure. Incidence rate ratios (IRRs) were calculated and multivariate analyses conducted using extended Cox models. Results: A total of 93 106 patients met the entry criteria. Lovastatin exposure was associated with a lower incidence of all endpoints, including the primary outcome (IRR = 0.28, 95% CI 0.12, 0.55), moderate liver injury (IRR = 0.56, 95% CI 0.47, 0.65), severe liver injury (IRR = 0.50, 95% CI 0.29, 0.81) and the occurrence of either cirrhosis or liver failure (IRR = 0.29, 95% CI 0.21, 0.38); adjustment for age and sex resulted in some attenuation of this reduction in incidence. The observed effects were generally consistent across a range of baseline liver-disease diagnoses and greater cumulative lovastatin exposure was associated with fewer outcome events for some endpoints. Conclusions: In this retrospective analysis, exposure to lovastatin was not associated with an increased risk of adverse hepatic outcomes. These results do not support concern regarding lovastatin-related hepatotoxicity in patients with existing liver disease.

ABSTRACT SCF-type E3 ubiquitin ligases use F-box (FBX) proteins as interchangeable substrate adaptors to recruit protein targets for ubiquitylation. FBX proteins almost universally have structure with two domains. A conserved N-terminal F-box domain interacts with a SKP protein and connects the FBX protein to the core SCF complex, while a C-terminal domain interacts with the protein target and facilitates recruitment. The F-BOX STRESS INDUCED (FBS) subfamily of four plant FBX proteins has atypical domain structure, however, with a centrally located F-box domain and additional conserved regions at both the N- and C-termini. FBS proteins have been linked to environmental stress networks, but no ubiquitylation target(s) or exact biological function has been established for this subfamily. We have identified two WD40 repeat-like proteins in Arabidopsis that are highly conserved in plants and interact with FBS proteins, which we have named FBS INTERACTING PROTEINs (FBIPs). FBIPs interact exclusively with the N-terminus of FBS proteins, and this interaction occurs in the nucleus. FBS1 destabilizes FBIP1, consistent with FBIPs being ubiquitylation targets of SCFFBS complexes. Furthermore, we found that FBIP1 interacts with NIGT1.1, a GARP-type transcriptional repressor that regulates nitrate and phosphate starvation signaling and responses. Collectively, these interactions between FBS, FBIP, and NIGT1.1 proteins delineate a previously unrecognized SCF-connected transcription regulation module that works in the context of phosphate and nitrate starvation, and possibly other environmental stresses. Importantly, this work also identified two uncharacterized WD40 repeat-like proteins as new tools with which to probe how an atypical SCF complex, SCFFBS, functions via FBX protein N-terminal interaction events. Competing Interest Statement The authors have declared no competing interest.

In this paper, we propose that spiritual approaches rooted in the practice of Hawai‘i ritual provide a powerful portal to revealing, supporting, and enhancing our collective aloha (love, fondness, reciprocity, as with a family member) for and dedication to the places and processes that we steward. We provide a case study from Hawai‘i, where we, a group of conservation professionals known as Hālau ‘Ōhi’a, have begun to foster a collective resurgence of sacred commitment to the places and processes we steward through remembering and manifesting genealogical relationships to our landscapes through Indigenous Hawaiian ritual expression. We discuss how a ritual approach to our lands and seas makes us better stewards of our places, better members of our families and communities, and more fulfilled individuals. We assert that foundations of the spiritual and the sacred are required for effectively advancing the science of sustainability, the management of natural resources, and the conservation of nature.