Ethylene is a well-established negative regulator of nodulation, yet how ethylene biosynthesis and perception are spatially coordinated during early symbiotic signaling remains unresolved. Here, we investigate the dynamics of ethylene responses in Medicago (Medicago truncatula) using transcriptomics, promoter-reporter analyses, loss-of-function approaches and a synthetic reporter. We show that the activity of the ethylene-responsive EBSn reporter shifts from inner root tissues under nonsymbiotic conditions to the outer cortex and epidermis following rhizobial inoculation, revealing a spatial reprogramming of ethylene signaling. Among the 8 Medicago 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASE (ACS) genes, MtACS3 is induced in outer root cell layers upon rhizobia application, while MtACS10 is repressed in the inner cortex and pericycle, mirroring the shift in ethylene perception. Functional analysis demonstrates that MtACS10 restricts nodule initiation, whereas MtACS3 modulates the number of infection threads, prevents nodule clustering, and contributes to the radial positioning of nodule primordia. Rhizobial induced ectopic ACS expression in the root interior counteracts MtACS10 repression and blocks nodulation, highlighting the requirement for spatially confined downregulation of ethylene biosynthesis. Together, these findings establish a framework in which localized shifts in ethylene biosynthesis, mediated by distinct Medicago ACS genes, balance infection and organogenesis while co-defining the spatial limits of the root susceptible zone.

Nitrogen-fixing nodule symbiosis is an ecologically and economically important trait in legumes and some related species. A critical step in the evolution of nodulation is the recruitment of NODULE INCEPTION (NIN); a homolog of the nitrate-sensing NIN-LIKE PROTEIN (NLP) transcription factors. However, whether adaptations have occurred in the NIN protein upon its recruitment in symbiosis remains elusive. Here we show that non-symbiotic NIN orthologs can function in intracellular infection and even nodule initiation, indicating that these properties of NIN predate the evolution of nodulation. Concurrent with the evolution of nodulation, symbiotic NIN proteins were optimized for their role in symbiosis by acquiring nitrate independent functionality, including constitutive nuclear localization. A single amino acid substitution in the non-symbiotic Arabidopsis AtNLP2 enhances its nuclear localization under low nitrate conditions, making it functionally comparable to the symbiotic Parasponia PanNIN. Our study provides insight in the evolutionary trajectory and molecular adaptation that allowed NIN to function as the central regulator of nitrogen-fixing nodule symbiosis.

SUMMARY Legume nodule formation is induced by rhizobia secreted Nod factors (NFs). It has been shown that NF receptors also accumulate in the apex of Medicago truncatula nodules. However, the NF signaling induced transcriptional changes in there have never been studied. Here, we studied this by using NF signaling mutant TE7, a weak allele of IPD3, blocked in rhizobial release. Nodule apices were isolated with laser microdissection and used for transcriptional analysis. We identified 1655 NF signaling controlled genes in nodule apex. By comparing this with the transcriptome data from VAMP721d&e RNAi nodule apices, we identified a subset of 445 genes whose expression depends on NF signaling and rhizobial release. Further, we compared the set of genes controlled by NF signaling in nodule apices with that controlled in root epidermis, and these showed only a small overlap. NIN is induced by NF signaling both in the root epidermis and in the nodule. By overexpression of NIN in TE7 and knock down of NIN in wildtype nodules we showed that NF signaling controlled rhizobial release depends on NIN. NF signaling controls a distinct set of genes in nodules, the function of which depends at least in part on NIN.

PLETHORA transcription factors (PLTs) are master regulators of plant development. Loss of shoot meristematic PLTs leads to reduced phyllotactic regularity and robustness in Arabidopsis and increased inflorescence branching in tomato. Whether these factors have similar functions in other species is not known. To address this knowledge gap, we integrated phylogenetic, transcriptomic, and genome-wide in vitro binding strategies with quantitative shoot architecture phenotyping of a panel of cucumber TILLING mutants of each CsPLT homolog. We determined that CsPLT3/7 and CsPLT5 are expressed in complementary domains in the cucumber shoot apex. DAP-seq data indicated that both transcription factors recognised an ANT-like consensus motif and bound to SAM-organising genes. We identified strong phenotypic defects in multiple Csplt3/7 mutants. In mature seeds, Csplt3/7 mutants formed a flat apex instead of a shoot apical meristem, from which secondary meristems emerged during subsequent seedling development. Mature Csplt3/7 shoots exhibited defects in internode length regularity, stem architecture, flower morphology, and axillary organ initiation. Moreover, phyllotactic patterns were slightly shifted from a spiral towards a distichous orientation. We present one of the first pieces of evidence that the PLT3/7 clade fulfils both conserved and diversified roles in shoot development across taxonomic family boundaries.

Nitrogen-fixing nodule symbiosis is an ecologically and economically important trait in legumes and some related species. A critical step in the evolution of nodulation is the recruitment of NODULE INCEPTION (NIN); a homolog of the nitrate-sensing NIN-LIKE PROTEIN (NLP) transcription factors. However, whether adaptations have occurred in the NIN protein upon its recruitment in symbiosis remains elusive. Here we show that non-symbiotic NIN orthologs can function in intracellular infection and even nodule initiation, demonstrating that these properties of NIN predate the evolution of nodulation. Concurrent with the evolution of nodulation, symbiotic NIN proteins were optimized for their role in symbiosis by acquiring nitrate independent functionality, including constitutive nuclear localization. A single amino acid substitution in Arabidopsis AtNLP2 enhances its nuclear localization under low nitrate conditions, making it functionally comparable to a symbiotic NIN. These findings highlight that NIN was predisposed to function in nodulation at the time of its recruitment into nitrogen-fixing symbiosis. Our study provides novel insight in how and why non-symbiotic NIN orthologues could be recruited to function in nitrogen-fixing root nodule symbiosis. ### Competing Interest Statement Some findings in this manuscript are considered for patent application. Enabling Nutrient Symbioses in Agriculture (ENSA) that is funded by Bill & Melinda Gates Agricultural Innovations, INV- 57461 China Scholarship Council, 201506300062, 201906170085, 202008150090 Nederlandse Organisatie voor Wetenschappelijk Onderzoek, VI.Veni.212.132

The importance of auxin in plant organ development, including root nodule formation, is well known. The spatiotemporal distribution pattern of auxin during nodule development has been illustrated using auxin reporter constructs. However, our understanding of how this pattern is established and maintained remains elusive. Here, we studied how the auxin gradient is associated with the spatiotemporal expression patterns of known auxin biosynthesis and transport genes at different stages of nodule development in Medicago (Medicago truncatula). In addition, we examined the Medicago PIN-FORMED10 (MtPIN10) expression pattern and polar positioning on the cell membrane during nodule primordium development to investigate auxin flux. RNA interference and the application of auxin biosynthesis inhibitors were used to demonstrate the importance of auxin biosynthesis and transport at the initial stages of nodulation. Our results show that upon rhizobium inoculation before the first cell divisions, a specific subset of Medicago YUCCA (MtYUC) and MtPIN genes, as well as Medicago LIKE AUXIN RESISTANT2 (MtLAX2), are expressed in the pericycle and contribute to the creation of an auxin maximum. Overall, we demonstrate that the dynamic spatiotemporal expression of both MtYUC and MtPIN genes results in specific auxin outputs during the different stages of nodule primordia and nodule meristem formation.

The hallmark of the legume lncRNA EARLY NODULIN40 (ENOD40), involved in rhizobium-induced nodulation, is the presence of a highly conserved stretch of 24 nucleotides, designated box2, preceded by a small open-reading-frame (sORF) coding for a peptide of 12 to 13 amino acids. Although there is a well-established link between ENOD40 and nodulation, it is not fully clear by which mechanism ENOD40 functions in this process. Here, we show that a region harboring box2 can complement nodule formation in an ENOD40 knock-out mutant (enod40-1-2/1). The sequence of box2 bears the characteristics of a miR169 target mimic. We show that the artificial target mimic MIM169defg can indeed complement the reduced capability of nodule formation in enod40-1-2/1, and that box2 exhibits target mimic activity in a transient luciferase assay. In addition, the introduction of a miR169-resistant form of MtNF-YA1 also elevates the capacity to form nodules in enod40-1-2/1. We conclude that ENOD40 effectuates nodule initiation by posttranscriptional upregulation of the miR169 target NF-YA1, which encodes an essential transcription factor in this step of the nodulation process.

In the current warming climate, many organisms in seasonal environments advance their timing of reproduction to benefit from resource peaks earlier in spring. For migrants, the potential to advance reproduction may be constrained by their migration strategies, notably their ability to advance arrival at the breeding grounds. Recent studies show various changes in migration strategies, including wintering closer to the breeding grounds, earlier departure from the wintering grounds or faster travels by spending less time at stopover sites. However, whether such changes lead to earlier arrival or earlier breeding remains an open question. We studied changes in migration and reproduction timing in 12 populations of nine migratory birds, including seabirds, shorebirds, birds of prey and waterfowl breeding at Arctic sites bordering the Greenland and Barents Sea, a region undergoing rapid climate warming. The timing of migration and reproduction was derived from tracking and field data and analysed to study (1) how timing has changed in response to the changing moment of snowmelt at the breeding grounds and (2) what adjustments in migration strategies this involved. We found that in years with early snowmelt, egg-laying in multiple populations advanced, but only two waterfowl populations also advanced arrival in the Arctic. In contrast, arrival in the Arctic generally advanced with time, even when snowmelt or egg-laying dates did not advance. Earlier arrival with time was mostly explained by populations traveling to the Arctic faster, likely spending less time at stopover sites. Inability to forecast conditions in the Arctic may limit birds to adjust migration timing to annually varying snowmelt, but we show that several species, particularly waterfowl, are able to travel faster and advance the timing of migration over the years. The question remains whether this reflects adaptations to Arctic climate change or other factors, for example, environmental changes along the migratory route.

The stability of carnosine, pyrrolylcarnosine (PC) and salicylcarnosine (SC) to the action of leucine aminopeptidase, carboxypeptidases B and Y was evaluated. It was found that proteolysis of carnosine, PC and SC under the action of leucine aminopeptidase does not occur. Carboxypeptidases B and Y, as well as the enzyme system of blood plasma and plasma membranes of rat brain cells, degraded peptides containing β-alanyl, N-pyrrolyl, N-salicylic fragments to varying degrees. In all cases, histidine is formed. The formation of pyrrole or salicylic acid does not occur. It was found that carnosine, PC and SC showed high stability to the action of amino- and carboxypeptidases in in vitro experiments.

Advances in tracking technologies have revealed the diverse migration patterns of birds, which are critical for range mapping and population estimation. Population trends are usually estimated in breeding ranges where birds remain stationary, but for species that breed in remote areas like the Arctic, these trends are often assessed in over-wintering ranges. Assessing population trends during the wintering season is challenging due to the extensive movements of birds in these ranges, which requires a deep understanding of the movement dynamics. However, these movements remain understudied, particularly in the mid-latitudes, where many Arctic breeders overwinter, increasing uncertainty in their ranges and numbers. Here, we show that the Arctic breeding raptor Rough-legged buzzard, which overwinters in the mid-latitudes, has a specific wintering strategy. After migrating ca. 1500 km from the Arctic to mid-latitudes, the birds continue to move throughout the entire over-wintering period, traveling another 1000 km southwest and then back northeast as the snowline advances. This continuous movement makes their wintering range dynamic throughout the season. In essence, this movement represents an extension of the quick migration process, albeit at a slower pace, and we have termed this migration pattern ‘foxtrot migration’, drawing an analogy to the alternating fast and slow movements of the foxtrot dance. These results highlight the potential errors in range mapping from single mid-winter surveys and emphasize the importance of this migration pattern in assessing the conservation status of bird species. Understanding this migration pattern could help to correctly estimate bird populations in over-wintering ranges, which is especially important for species that nest in hard-to-reach regions such as the Arctic.

The behavioral and functional states preceding the onset of specific parkinsonian symptoms were studied at an early (presymptomatic) stage of hemi-parkinsonian syndrome development in rodents and monkeys. The consecutive steps of neuropathological traits development—cognitive impairments developing from weeks 1–2 of rotenone exposure, minor motor impairments on weeks 3–4 before the development of pronounced motor dysfunction, and some biochemical indicators—were studied using the model of hemi-parkinsonian syndrome in rodents induced by chronic administration of low doses of rotenone toxin. The characteristics of visually guided saccades (VGS) while an instrumental conditioning task performing were studied using the model of hemi-parkinsonian syndrome in nonhuman primates (Macaca mulatta) chronically treated with low doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxin. As MPTP syndrome progresses, an increase in the latencies of VGS and a decline in their accuracy with the retention of an instrumental conditioning performance have been shown. The negative behavioral effects in rodents and primates and biochemical effects in rodents manifested at the presymptomatic stage of the disease, suggest to consider them as early markers of a hemi-parkinsonian syndrome.

Researchers have identified Avastrovirus as a significant genus of bird viruses, linked to various avian diseases such as enteritis, growth retardation, nephritis and hepatitis. These infections can cause substantial economic losses in agrocultureand have a widespread impact on global food production. Although there have been numerous studies on these viruses, most of them-mainly focuses on poultry. Research on astroviruses in wild bird populations has revealed a wide genetic diversity of these viruses, yet our understanding of their biological and ecological characteristics remains limited. In this study, we for the first time detected avastrovirus in wild migratory birds of the families Anatidae and Columbidae from Sakhalin Island, North Pacific Ocean. Phylogenetic analysis revealed the presence of Avastrovirus 2 in wild doves and Avastrovirus 3 in wild ducks. These findings provide valuable insights into the circulation of astroviruses in wild bird populations of Sakhalin Island, which lies along the East Asian-Australasian Flyway.

The new conjugate compound pyrrolylcarnosine was synthesized from the natural antioxidant carnosine and the aromatic five-membered nitrogen heterocycle pyrrole. The synthesis of pyrrolylcarnosine was described. Its physicochemical properties and biological activity in various oxidative stress models were evaluated. The results showed that pyrrolylcarnosine was characterized by resistance to hydrolysis by serum carnosinase and exhibited high antioxidant activity in model experiments. It had a neuroprotective effect under oxidative stress induced by the neurotoxin AAPH, increasing the viability of a differentiated culture of human neuroblastoma SH-SY5Y and protecting it from death. In general, the results indicated creation of a new drug based on pyrrolylcarnosine was promising.

Abstract Advances in tracking technologies have revealed the diverse migration patterns of birds, which are critical for range mapping and population estimation. While population trends are typically estimated in breeding ranges where birds remain stationary, trends are commonly assessed in non-breeding ranges for species that breed in inaccessible regions such as the Arctic. This task is challenging due to the extensive movements of birds in these ranges, which require a deep understanding of the dynamics of these movements. However, these movements remain understudied, particularly in the mid-latitudes, where many Arctic breeders winter, increasing the risk of misestimating their ranges and numbers. Here, we show that the Arctic breeding raptor Rough-legged buzzard, which overwinters in the mid-latitudes, has a specific wintering strategy: during the entire non-breeding season, they move about 1000 km back and forth under the influence of the advancing snowline, making their non-breeding area dynamic. In essence, this movement represents an extension of the quick migration process, albeit at a slower pace, and we have termed this migration pattern ‘foxtrot migration,’ drawing an analogy to the alternating fast and slow movements of the foxtrot dance. These results highlight the potential errors in range mapping from single mid-winter surveys and emphasize the importance of this migration pattern in assessing the conservation status of bird species. Understanding this migration pattern helps to correctly estimate bird populations in non-breeding areas, which is especially important for species that nest in hard-to-reach regions such as the Arctic.

На основе природного антиоксиданта карнозина и ароматического пятичленного азотистого гетероцикла пиррола нами было синтезировано новое конъюгированное соединение — пирролилкарнозин. В данном исследовании описан синтез пирролилкарнозина, дана оценка его физико-химических свойств и биологической активности в различных моделях окислительного стресса. Результаты проведенного исследования показали, что пирролилкарнозин характеризуется устойчивостью к гидролизу сывороточной карнозиназой, высокой антиоксидантной активностью в модельных экспериментах и оказывает нейропротекторное действие в условиях индукции окислительного стресса нейротоксином ААРН, повышая жизнеспособность дифференцированной культуры нейробластомы человека SH-SY5Y и защищая ее от гибели. В целом, полученные результаты указывают на перспективность создания нового лекарственного средства на основе пирролилкарнозина.

The experimental study of the pharmacokinetic characteristics of a new pyrrole derivative of carnosine, pyrrolylcarnosine, was carried out. Based on the results of the experiment, the basic pharmacokinetic parameters of the drug are expected. The tissues and organs bioavailability was studied. The tropism of pyrrolylcarnosine to the organs of elimination and the ability of pyrrolylcarnosine to penetrate into the heart muscle tissue were shown.