Hydrogen peroxide (H2O2) is a stable component of reactive oxygen species, and its production in plants represents the successful recognition of pathogen infection and pathogen-associated molecular ...patterns (PAMPs). This production of H₂O₂ is typically apoplastic but is subsequently associated with intracellular immunity pathways that regulate disease resistance, such as systemic acquired resistance and PAMP-triggered immunity. Here, we elucidate that an Arabidopsis (Arabidopsis thaliana) aquaporin (i.e. the plasma membrane intrinsic protein AtPIP1;4) acts to close the cytological distance between H₂O₂ production and functional performance. Expression of the AtPIP1;4 gene in plant leaves is inducible by a bacterial pathogen, and the expression accompanies H₂O₂ accumulation in the cytoplasm. Under de novo expression conditions, AtPIP1;4 is able to mediate the translocation of externally applied H₂O₂ into the cytoplasm of yeast (Saccharomyces cerevisiae) cells. In plant cells treated with H₂O₂, AtPIP1;4 functions as an effective facilitator of H₂O₂ transport across plasma membranes and mediates the translocation of externally applied H₂O₂ from the apoplast to the cytoplasm. The H₂O₂-transport role of AtPIP1;4 is essentially required for the cytoplasmic import of apoplastic H₂O₂ induced by the bacterial pathogen and two typical PAMPs in the absence of induced production of intracellular H₂O₂. As a consequence, cytoplasmic H₂O₂ quantities increase substantially while systemic acquired resistance and PAMP-triggered immunity are activated to repress the bacterial pathogenicity. By contrast, loss-of-function mutation at the AtPIP1;4 gene locus not only nullifies the cytoplasmic import of pathogen-and PAMP-induced apoplastic H₂O₂ but also cancels the subsequent immune responses, suggesting a pivotal role of AtPIP1;4 in apocytoplastic signal transduction in immunity pathways.
Let X be a variety defined over an algebraically closed field k of characteristic 0, let N\in \mathbb{N}, let g:X\dashrightarrow X be a dominant rational self-map, and let ...A:\mathbb{A}^N\longrightarrow \mathbb{A}^N be a linear transformation defined over k(X), i.e., for a Zariski open dense subset U\subset X, we have that for x\in U(k), the specialization A(x) is an N-by- N matrix with entries in k. We let f:X\times \mathbb{A}^N\dashrightarrow X\times \mathbb{A}^N be the rational endomorphism given by (x,y)\mapsto (g(x), A(x)y). We prove that if the determinant of A is nonzero and if there exists x\in X(k) such that its orbit \mathcal {O}_g(x) is Zariski dense in X, then either there exists a point z\in (X\times \mathbb{A}^N)(k) such that its orbit \mathcal {O}_f(z) is Zariski dense in X\times \mathbb{A}^N or there exists a nonconstant rational function \psi \in k(X\times \mathbb{A}^N) such that \psi \circ f=\psi . Our result provides additional evidence to a conjecture of Medvedev and Scanlon.
The aims of this paper are to answer several conjectures and questions about the multiplier spectrum of rational maps and giving new proofs of several rigidity theorems in complex dynamics by ...combining tools from complex and non-Archimedean dynamics. A remarkable theorem due to McMullen asserts that, aside from the flexible Lattès family, the multiplier spectrum of periodic points determines the conjugacy class of rational maps up to finitely many choices. The proof relies on Thurston’s rigidity theorem for post-critically finite maps, in which Teichmüller theory is an essential tool. We will give a new proof of McMullen’s theorem (and therefore a new proof of Thurston’s theorem) without using quasiconformal maps or Teichmüller theory. We show that, aside from the flexible Lattès family, the length spectrum of periodic points determines the conjugacy class of rational maps up to finitely many choices. This generalizes the aforementioned McMullen’s theorem. We will also prove a rigidity theorem for marked length spectrum. Similar ideas also yield a simple proof of a rigidity theorem due to Zdunik. We show that a rational map is exceptional if and only if one of the following holds: (i) the multipliers of periodic points are contained in the integer ring of an imaginary quadratic field, and (ii) all but finitely many periodic points have the same Lyapunov exponent. This solves two conjectures of Milnor.
Let
f
:
X
→
X
be a surjective endomorphism of a normal projective surface. When
deg
f
≥
2
, applying an (iteration of)
f
-equivariant minimal model program (EMMP), we determine the geometric ...structure of
X
. Using this, we extend the second author’s result to singular surfaces to the extent that either
X
has an
f
-invariant non-constant rational function, or
f
has infinitely many (disjoint) Zariski-dense forward orbits; this result is also extended to adelic topology (which is finer than Zariski topology).
Nitrogen (N) is a major limiting factor for plant growth and crop production. The use of N fertilizer in forestry production is increasing each year, but the loss is substantial. Mastering the ...regulatory mechanisms of N uptake and transport is a key way to improve plant nitrogen use efficiency (NUE). However, this has rarely been studied in pecans. In this study, 10 AMT and 69 NRT gene family members were identified and systematically analyzed from the whole pecan genome using a bioinformatics approach, and the expression patterns of AMT and NRT genes and the uptake characteristics of NH4+ and NO3− in pecan were analyzed by aeroponic cultivation at varying NH4+/NO3− ratios (0/0, 0/100,25/75, 50/50, 75/25,100/0 as CK, T1, T2, T3, T4, and T5). The results showed that gene duplication was the main reason for the amplification of the AMT and NRT gene families in pecan, both of which experienced purifying selection. Based on qRT-PCR results, CiAMTs were primarily expressed in roots, and CiNRTs were majorly expressed in leaves, which were consistent with the distribution of pecan NH4+ and NO3− concentrations in the organs. The expression levels of CiAMTs and CiNRTs were mainly significantly upregulated under N deficiency and T4 treatment. Meanwhile, T4 treatment significantly increased the NH4+, NO3−, and NO2− concentrations as well as the Vmax and Km values of NH4+ and NO3− in pecans, and Vmax/Km indicated that pecan seedlings preferred to absorb NH4+. In summary, considering the single N source of T5, we suggested that the NH4+/NO3− ratio of 75:25 was more beneficial to improve the NUE of pecan, thus increasing pecan yield, which provides a theoretical basis for promoting the scale development of pecan and provides a basis for further identification of the functions of AMT and NRT genes in the N uptake and transport process of pecan.
Nitrogen (N) limits plant productivity, and its uptake and assimilation may be regulated by N sources, N assimilating enzymes, and N assimilation genes. Mastering the regulatory mechanisms of N ...uptake and assimilation is a key way to improve plant nitrogen use efficiency (NUE). However, it is poorly known how these factors interact to influence the growth process of pecans. In this study, the growth, nutrient uptake and N assimilation characteristics of pecan were analyzed by aeroponic cultivation at varying
NH
4
+
/
NO
3
−
ratios (0/0, 0/100,25/75, 50/50, 75/25,100/0 as CK, T1, T2, T3, T4, and T5). The results showed that T4 and T5 treatments optimally promoted the growth, nutrient uptake and N assimilating enzyme activities of pecan, which significantly increased aboveground biomass, average relative growth rate (RGR), root area, root activity, free amino acid (FAA) and total organic carbon (TOC) concentrations, nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (Fd-GOGAT and NADH-GOGAT), and glutamate dehydrogenase (GDH) activities. According to the qRT-PCR results, most of the N assimilation genes were expressed at higher levels in leaves and were mainly significantly up-regulated under T1 and T4 treatments. Correlation analysis showed that a correlation between N assimilating enzymes and N assimilating genes did not necessarily exist. The results of partial least squares path model (PLS-PM) analysis indicated that N assimilation genes could affect the growth of pecan by regulating N assimilation enzymes and nutrients. In summary, we suggested that the
NH
4
+
/
NO
3
−
ratio of 75:25 was more beneficial to improve the growth and NUE of pecan. Meanwhile, we believe that the determination of plant N assimilation capacity should be the result of a comprehensive analysis of N concentration, N assimilation enzymes and related genes.
Bacteria play determining roles in forest soil environment and contribute to essential functions in the cycling of nitrogen (N) and phosphorus (P). Understanding the effects of different fertilizer ...applications, especially successive fertilization, on soil properties and bacterial community could reveal the impacts of fertilization on forest soil ecology and shed light on the nutrient cycling in forest system. This study aimed to evaluate the impacts of successive mineral N (NH
4
NO
3
) and P (NaH
2
PO
4
) fertilization at different rates, alone or together, on soil bacterial biomass and communities at 0–5, 5–10, and 10–20 cm. Compared with the control, N fertilization decreased soil pH, but P alone or with N fertilization had negligibly negative impacts on soil pH. Different mineral fertilizer applications, alone or together, showed no significant effects on soil organic matter contents, relative to the control treatment. Bacterial biomass remained stable to different fertilizations but decreased with sampling depths. Sole N or P fertilization, rather than combined fertilizations, significantly changed soil bacterial community structures. Our results demonstrated that mineral N or P fertilization alone significantly affected bacterial community structures rather than biomass in the plantation soils.
Key points
• Impacts of successive mineral fertilization on soil bacteria were determined.
• Mineral fertilization showed negligible impacts on bacterial biomass.
• N additions stimulated Chloroflexi relative abundances.
• Mineral N or P fertilization significantly altered bacterial community structure.
In this paper, we study arithmetic dynamics in arbitrary characteristic, in particular in positive characteristic.
Applying the arithmetic degree and canonical height in positive characteristic, we ...prove the Dynamical Mordell–Lang Conjecture for automorphisms of projective surfaces of positive entropy, the Zariski Dense Orbit Conjecture for automorphisms of projective surfaces and for endomorphisms of projective varieties with large first dynamical degree.
We also study ergodic theory for constructible topology. For example, we prove the equidistribution of backward orbits for finite flat endomorphisms with large topological degree. As applications, we give a simple proof for weak dynamical Mordell–Lang and prove a counting result for backward orbits without multiplicities. This gives some applications for equidistributions on Berkovich spaces.
Studies have shown that low childhood socioeconomic status (SES) is associated with a high prevalence of depressive symptoms. Childhood trauma, as a potential consequence of low SES, may play an ...important part, but the mediation effect of childhood trauma remains to be elucidated.
A cross-sectional survey was conducted among 1,807 university students. The MacArthur Scale of Subjective Social Economic Status-Youth Version, Childhood Trauma Questionnaire, and Beck Depression Inventory were used to measure childhood SES, childhood trauma, and current depressive symptoms, respectively. A structural equation model (SEM) was employed to demonstrate the mediating role of childhood trauma on the association between childhood SES and depressive symptoms.
The SEM demonstrated that childhood SES had significant indirect effects upon depressive symptoms
childhood trauma. Childhood trauma accounted for 89.3% of the total effect, indicating a profound mediation effect.
The effect of childhood SES on the depressive symptoms of young adults was mediated by childhood trauma, which emphasizes the importance of early prevention and intervention of child neglect/abuse.
In this paper we prove the following theorem. Let $f$ be a dominant endomorphism of a smooth projective surface over an algebraically closed field of characteristic $0$. If there is no nonconstant ...invariant rational function under $f$, then there exists a closed point whose orbit under $f$ is Zariski dense. This result gives us a positive answer to the Zariski dense orbit conjecture proposed by Medvedev and Scanlon, by Amerik, Bogomolov and Rovinsky, and by Zhang, for endomorphisms of smooth projective surfaces. Moreover, we define a new canonical topology on varieties over an algebraically closed field which has finite transcendence degree over $\mathbb{Q}$. We call it the adelic topology. The adelic topology is stronger than the Zariski topology and an irreducible variety is still irreducible in this topology. Using the adelic topology, we propose an adelic verison of the Zariski dense orbit conjecture. This version is stronger then the original one and it quantifies how many such orbits there are. We also proved this adelic version for endomorphisms of smooth projective surfaces. Moreover, we proved the adelic verison of the Zariski dense orbit conjecture for endomorphisms of abelian varieties and split polynomial maps. This yields new proofs for the original version in this two cases. In Appendix A, we study the endomorphisms on the $k$-affinoid spaces. We show that for certain endomorphism $f$ on a $k$-affinoid space $X$, the attractor $Y$ of $f$ is a Zariski closed subset and the dynamics of $f$ semi-conjugates to its restriction on $Y.$ A special case of this result is used in the proof of the main theorem. In Appendix B, written in collaboration with Thomas Tucker, we prove the Zariski dense orbit conjecture for endomorphisms of $(\mathbb{P}^1)^N.$
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