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• Anthocyanin and proanthocyanidin (PA) accumulation is regulated by both myeloblastosis (MYB) activators and repressors, but little information is available on hierarchical interactions between the positive and negative regulators. Here, we report on a R2R3-MYB repressor in peach, designated PpMYB18, which acts as a negative regulator of anthocyanin and PA accumulation. • PpMYB18 can be activated by both anthocyanin- and PA-related MYB activators, and is expressed both at fruit ripening and juvenile stages when anthocyanins or PAs, respectively, are being synthesized. • The PpMYB18 protein competes with MYB activators for binding to basic Helix Loop Helixes (bHLHs), which develops a fine-tuning regulatory loop to balance PA and anthocyanin accumulation. In addition, the bHLH binding motif in the R3 domain and the C1 and C2 repression motifs in the C-terminus of PpMYB18 both confer repressive activity of PpMYB18. • Our study also demonstrates a modifying negative feedback loop, which prevents cells from excess accumulation of anthocyanin and PAs, and serves as a model for balancing secondary metabolite accumulation at the transcriptional level.

Identified as essential mechanisms promoting alternative stable states, positive feedbacks have been the focus of most former studies on the potential for catastrophic shifts in drylands. Conversely, little is known about how negative feedbacks could counterbalance the effects of positive feedbacks. A decrease in vegetation cover increases the connectivity of bare-soil areas and entails a global loss of runoff-driven resources from the ecosystem but also a local increase in runoff transferred from bare-soil areas to vegetation patches. In turn, these global resource losses and local resource gains decrease and increase vegetation cover, respectively, resulting in a global positive and a local negative feedback loop. We propose that the interplay of these two interconnected ecohydrological feedbacks of opposite sign determines the vulnerability of dryland ecosystems to catastrophic shifts. To test this hypothesis, we developed a spatially explicit model and assessed the effects of varying combinations of feedback strengths on the dynamics, resilience, recovery potential, and spatial structure of the system. Increasing strengths of the local negative feedback relative to the global positive feedback decreased the risk of catastrophic shifts, facilitated recovery from a degraded state, and promoted the formation of banded vegetation patterns. Both feedbacks were most relevant at low vegetation cover due to the nonlinear increase in hydrological connectivity with decreasing vegetation. Our modelling results suggest that catastrophic shifts to degraded states are less likely in drylands with strong source–sink dynamics and/or strong response of vegetation growth to resource redistribution and that feedback manipulation can be useful to enhance dryland restoration.

Leaf architecture directly determines canopy structure, and thus, grain yield in crops. Leaf droopiness is an agronomic trait primarily affecting the cereal leaf architecture but the genetic basis and underlying molecular mechanism of this trait remain unclear. Here, we report that DROOPY LEAF1 (DPY1), an LRR receptor-like kinase, plays a crucial role in determining leaf droopiness by controlling the brassinosteroid (BR) signaling output in Setaria, an emerging model for Panicoideae grasses. Loss-of-function mutation in DPY1 led to malformation of vascular sclerenchyma and low lignin content in leaves, and thus, an extremely droopy leaf phenotype, consistent with its preferential expression in leaf vascular tissues. DPY1 interacts with and competes for SiBAK1 and as a result, causes a sequential reduction in SiBRI1–SiBAK1 interaction, SiBRI1 phosphorylation, and downstream BR signaling. Conversely, DPY1 accumulation and affinity of the DPY1–SiBAK1 interaction are enhanced under BR treatment, thus preventing SiBRI1 from overactivation. As such, those findings reveal a negative feedback mechanism that represses leaf droopiness by preventing an overresponse of early BR signaling to excess BRs. Notably, plants overexpressing DPY1 have more upright leaves, thicker stems, and bigger panicles, suggesting potential utilization for yield improvement. The maize ortholog of DPY1 rescues the droopy leaves in dpy1, suggesting its conserved function in Panicoideae. Together, our study provides insights into how BR signaling is scrutinized by DPY1 to ensure the upward leaf architecture.

• The patterning of adaxial–abaxial tissues plays a vital role in the morphology of lateral organs, which is maintained by antagonism between the genes that specify adaxial and abaxial tissue identity. The homeo-domain leucine zipper class III (HD-ZIP III) family genes regulate adaxial identity; however, little information is known about the physical interactions or transcriptionally regulated downstream genes of HD-ZIP III. • In this study, we identified a dominant rice mutant, lateral floret 1 (lf1), which has defects in lateral organ polarity. LF1 encodes the HD-ZIP III transcription factor, which expressed in the adaxial area of lateral organs. • LF1 can activate directly the expression of LITTLE ZIPPER family gene OsZPR4 and HD-ZIP II family gene OsHOX1, and OsZPR4 and OsHOX1 respectively interact with LF1 to form a heterodimer to repress the transcriptional activity of LF1. LF1 influences indole-3-acetic acid (IAA) content by directly regulating the expression of OsYUCCA6. Therefore, LF1 forms negative feedback loops between OsZPR4 and OsHOX1 to affect IAA content, leading to the regulation of lateral organs polarity development. • These results reveal the cross-talk among HD-ZIP III, LITTLE ZIPPER, and HD-ZIP II proteins and provide new insights into the molecular mechanisms underlying the polarity development of lateral organs.

Diverse extracellular proteins negatively regulate WNT signaling. One such regulator is adenomatosis polyposis coli down-regulated 1 (APCDD1), a conserved single-span transmembrane protein. In response to WNT signaling in a variety of tissues, APCDD1 transcripts are highly up-regulated. We have determined the three-dimensional structure of the extracellular domain of APCDD1, and this structure reveals an unusual architecture consisting of two closely apposed β-barrel domains (ABD1 and ABD2). ABD2, but not ABD1, has a large hydrophobic pocket that accommodates a bound lipid. The APCDD1 ECD can also bind to WNT7A, presumably via its covalently bound palmitoleate, a modification that is common to all WNTs and is essential for signaling. This work suggests that APCDD1 functions as a negative feedback regulator by titrating WNT ligands at the surface of responding cells.

The ocean surface and subsurface biophysical responses and their feedbacks to super typhoon Nida were comprehensively investigated based on a substantial dataset of multiple-satellite observations, Argo profiles, and reanalysis data. Nida experienced two Category 5 stages: a rapid intensification stage that was fast moving along a straight-line track, and a rapid weakening stage that was slowly moving along a sharp-left sudden-turning track. During the straight-line stage, Nida caused an average sea surface temperature (SST) cooling of 1.44 °C and a chlorophyll-a (chl-a) concentration increase of 0.03 mg m−3. During the sudden-turning stage, cyclonic sudden-turning induced a strong cold cyclonic eddy (SSHA < −60 cm) by strong upwelling, which caused the maximum SST cooling of 6.68 °C and a long-lasting chl-a bloom of 0.6 mg m−3 on the left-hand side of the track, resulting in substantial impacts on the ocean ecological environment. Furthermore, the enhanced ocean cold wake and the longer air–sea interaction in turn decreased the average inner-core SST of 4 °C and the corresponding enthalpy flux of 780 W m−2, which induced a notable negative feedback to the typhoon intensity by weakening it from Category 5 to Category 2. The left bias response and notable negative feedback are special due to sharp-left sudden-turning of typhoon. Comparing with the previously found slow translation speed (~4 m s−1) of significant ocean response, the negative feedback requires even more restriction of translation speed (<2 m s−1) and sharp sudden-turning could effectively relax restrictions by making equivalent translation speed lower and air-sea interaction time longer. Our findings point out that there are some unique features in ocean–typhoon interactions under sudden-turning and/or lingering tracks comparing with ordinary tracks.

In ant foraging, the manner of group-mass recruitment demonstrates remarkable adaptability between tandem running and mass recruitment. In contrast to tandem running, where a leader recruits only one worker, the first phase of group-mass recruitment is characterized by strong invitations from leaders that result in a large group of recruits leaving the nest together in a rush, thereby accelerating the process of recruiting towards discovered resources. Furthermore, unlike sole mass recruitment, the influence of leaders during this first phase enhances the accuracy of information about food qualities and ensures a more rational allocation of recruits compared to simply following a dominant pheromone trail. In this study, we propose a model that integrates the Kelly criterion for the first phase of group-mass recruitment, followed by a post-Kelly strategy incorporating a delayed Pólya urn with two stages for the second phase of group-mass recruitment. The analytical process and simulation demonstrate that the Kelly criterion aims to maximize recruitment intensity during the initial foraging phase, employing crowd tactics to capture all available food sources and enhance competitiveness with other food-exploiting species. On the other hand, the post-Kelly strategy elucidates how the crowding negative feedback mitigates congestion resulting from overexploitation and improves overall efficiency in food exploitation.

Purpose Drawing upon the feedback intervention theory, this study aims to focus on the concept of negative feedback change (increase or decrease) to analyze the dynamics of performance feedback and its relationships with goal orientation, feedback utility and task performance. Design/methodology/approach The authors conducted a two-wave survey by tracking 195 employees and their supervisors from two representative semiconductor-related equipment companies in China for one month. Findings Results showed that learning goal orientation positively moderates, and performance-approach goal orientation negatively moderates the indirect relationship between negative feedback change and employees’ task performance through employees’ perceptions of feedback utility. Originality/value This study provides new directions for performance feedback research by treating negative feedback from a dynamic perspective and addressing the mediating and moderating mechanisms. Furthermore, the findings also remind managers to not only consider feedback actions at a single moment but also manage it as a series of actions in the ongoing stream of time.

Zebrafish larvae show a rapid increase in cortisol in response to acute stressors, followed by a decline. While these responses are documented, both the duration of the refractory period to repeated stressors and the role of glucocorticoid receptors (GR) in specific phases of the glucocorticoid negative feedback are still being clarified. We explored these questions using water vortices as stressors, combined with GR blockage and measurements of whole-body cortisol in zebrafish larvae subjected to single and repeated stress protocols. Cortisol levels were elevated 10 min after stress onset and returned to baseline within 30-40 min, depending on the stressor strength. In response to homotypic stress, cortisol levels rose above baseline if the second stressor occurred 60 or 120 min after the first, but not with a 30-min interval. This suggests a rapid cortisol-mediated feedback loop with a refractory period of at least 30 min. Treatment with a GR blocker delayed the return to baseline and suppressed the refractory period, indicating GR-dependent early-phase feedback regulation. These findings are consistent with mammalian models and provide a framework for further analyses of early-life cortisol responses and feedback in zebrafish larvae, ideal for non-invasive imaging and high-throughput screening.

The influences of bypass current and wire feed speed are utilized to change the metal droplet transfer mode for bypass coupling wire-arcing additive manufacturing (BC-WAAW). To fully understand the influence of experimental factors on the wire melting process, this study establishes a mathematical model for the wire melting process, and several simulation experiments are carried out to prove the effectiveness of this mathematical model. The influence of changing the filler wire process on the stability of the wire melting process is simulated. A negative feedback control method with a single input and single output is proposed, which can control the stability of the wire melting process. The results show that the established mathematical model can well reflect the wire melting process in bypass coupling arcing additive manufacturing. The wire feed speed has a strong influence on the wire extension. The negative feedback control method can realize real-time control of filler wire process stability. The deposition process is more stable in the arcing additive manufacturing process, and the forming accuracy of a single multilayer deposition wall is further improved.