Foxp and Skor family proteins control differentiation of Purkinje cells from Ptf1a- and Neurog1-expressing progenitors in zebrafish.

Cerebellar neurons, such as GABAergic Purkinje cells (PCs), interneurons (INs) and glutamatergic granule cells (GCs) are differentiated from neural progenitors expressing proneural genes, including ptf1a, neurog1 and atoh1a/b/c. Studies in mammals previously suggested that these genes determine cerebellar neuron cell fate. However, our studies on ptf1a;neurog1 zebrafish mutants and lineage tracing of ptf1a-expressing progenitors have revealed that the ptf1a/neurog1-expressing progenitors can generate diverse cerebellar neurons, including PCs, INs and a subset of GCs in zebrafish. The precise mechanisms of how each cerebellar neuron type is specified remains elusive. We found that genes encoding the transcriptional regulators Foxp1b, Foxp4, Skor1b and Skor2, which are reportedly expressed in PCs, were absent in ptf1a;neurog1 mutants. foxp1b;foxp4 mutants showed a strong reduction in PCs, whereas skor1b;skor2 mutants completely lacked PCs, and displayed an increase in immature GCs. Misexpression of skor2 in GC progenitors expressing atoh1c suppressed GC fate. These data indicate that Foxp1b/4 and Skor1b/2 function as key transcriptional regulators in the initial step of PC differentiation from ptf1a/neurog1-expressing neural progenitors, and that Skor1b and Skor2 control PC differentiation by suppressing their differentiation into GCs.

SKOR1 mediates FER kinase-dependent invasive growth of breast cancer cells.

High expression of the non-receptor tyrosine kinase FER is an independent prognostic factor that correlates with poor survival in breast cancer patients. To investigate whether the kinase activity of FER is essential for its oncogenic properties, we developed an ATP analogue-sensitive knock-in allele (FERASKI). Specific FER kinase inhibition in MDA-MB-231 cells reduces migration and invasion, as well as metastasis when xenografted into a mouse model of breast cancer. Using the FERASKI system, we identified Ski family transcriptional corepressor 1 (SKOR1) as a direct FER kinase substrate. SKOR1 loss phenocopies FER inhibition, leading to impaired proliferation, migration and invasion, and inhibition of breast cancer growth and metastasis formation in mice. We show that SKOR1 Y234, a candidate FER phosphorylation site, is essential for FER-dependent tumor progression. Finally, our work suggests that the SKOR1 Y234 residue promotes Smad2/3 signaling through SKOR1 binding to Smad3. Our study thus identifies SKOR1 as a mediator of FER-dependent progression of high-risk breast cancers.

Gata2, Nkx2-2 and Skor2 form a transcription factor network regulating development of a midbrain GABAergic neuron subtype with characteristics of REM-sleep regulatory neurons.

The midbrain reticular formation (MRF) is a mosaic of diverse GABAergic and glutamatergic neurons that have been associated with a variety of functions, including sleep regulation. However, the molecular characteristics and development of MRF neurons are poorly understood. As the transcription factor, Gata2 is required for the development of all GABAergic neurons derived from the embryonic mouse midbrain, we hypothesized that the genes expressed downstream of Gata2 could contribute to the diversification of GABAergic neuron subtypes in this brain region. Here, we show that Gata2 is required for the expression of several GABAergic lineage-specific transcription factors, including Nkx2-2 and Skor2, which are co-expressed in a restricted group of post-mitotic GABAergic precursors in the MRF. Both Gata2 and Nkx2-2 function is required for Skor2 expression in GABAergic precursors. In the adult mouse and rat midbrain, Nkx2-2-and Skor2-expressing GABAergic neurons locate at the boundary of the ventrolateral periaqueductal gray and the MRF, an area containing REM-off neurons regulating REM sleep. In addition to the characteristic localization, Skor2+ cells increase their activity upon REM-sleep inhibition, send projections to the dorsolateral pons, a region associated with sleep control, and are responsive to orexins, consistent with the known properties of midbrain REM-off neurons.

NK-derived exosome miR-1249-3p inhibits Mycobacterium tuberculosis survival in macrophages by targeting SKOR1.

Murine Natural Killer cells were cultivated in vitro to isolate NK-derived exosomes. Subsequent quantification via qPCR confirmed enrichment of miR-1249-3p. Ana-1 murine macrophages were cultured in vitro and subsequently inoculated with Mycobacterium tuberculosis (MTB) strain H37Rv. NK-exo and NK-exo miR-1249-3p were separately applied to the infection model, followed by immunological assays conducted post-48-hour co-culture. Western blot analyses corroborated that NK-exo exhibited exosomal marker proteins Granzyme A (GzmA), Granzyme B (GzmB), and Perforin (PFN), alongside a notable enrichment of miR-1249-3p. Functionally, NK-exo augmented the expression levels of Caspase-9,-8, and -3, as well as PARP, while attenuating the expression of NLRP3, ASC, and Cleaved-Caspase-1. Furthermore, qPCR demonstrated an up-regulation of Caspase-9, -8, and -3, along with pro-apoptotic factors Bax and Bid, and a concomitant down-regulation of the anti-apoptotic factor Bcl-2. The expression levels of inflammatory markers ASC, NLRP3, Cleaved-Caspase-1, and IL-1ß were concomitantly decreased. ELISA findings indicated diminished levels of TNF-α and ROS secretion. NK-exo miR-1249-3p specifically targeted and attenuated the expression of SKOR-1, engendering up-regulation of apoptosis-associated proteins and down-regulation of inflammation-related proteins, consequently affecting cellular fate.Our empirical evidence substantiates that NK-exo induces macrophage apoptosis, thereby mitigating MTB survival. Furthermore, NK-exo miR-1249-3p directly targets and inhibits SKOR-1 expression, leading to macrophage apoptosis and consequently hampering the proliferation of MTB. The data implicate the potential therapeutic relevance of NK-exo and miR-1249-3p in managing drug-resistant tuberculosis.

Modulation of K+ translocation by AKT1 and AtHAK5 in Arabidopsis plants.

Root cells take up K+ from the soil solution, and a fraction of the absorbed K+ is translocated to the shoot after being loaded into xylem vessels. K+ uptake and translocation are spatially separated processes. K+ uptake occurs in the cortex and epidermis whereas K+ translocation starts at the stele. Both uptake and translocation processes are expected to be linked, but the connection between them is not well characterized. Here, we studied K+ uptake and translocation using Rb+ as a tracer in wild-type Arabidopsis thaliana and in T-DNA insertion mutants in the K+ uptake or translocation systems. The relative amount of translocated Rb+ to the shoot was positively correlated with net Rb+ uptake rates, and the akt1 athak5 T-DNA mutant plants were more efficient in their allocation of Rb+ to shoots. Moreover, a mutation of SKOR and a reduced plant transpiration prevented the full upregulation of AtHAK5 gene expression and Rb+ uptake in K+ -starved plants. Lastly, Rb+ was found to be retrieved from root xylem vessels, with AKT1 playing a significant role in K+ -sufficient plants. Overall, our results suggest that K+ uptake and translocation are tightly coordinated via signals that regulate the expression of K+ transport systems.

Physiological and molecular mechanisms mediating xylem Na+ loading in barley in the context of salinity stress tolerance.

Time-dependent kinetics of xylem Na+ loading was investigated using a large number of barley genotypes contrasting in their salinity tolerance. Salt-sensitive varieties were less efficient in controlling xylem Na+ loading and showed a gradual increase in the xylem Na+ content over the time. To understand underlying ionic and molecular mechanisms, net fluxes of Ca2+ , K+ and Na+ were measured from the xylem parenchyma tissue in response to H2 O2 and ABA; both of them associated with salinity stress signalling. Our results indicate that NADPH oxidase-mediated apoplastic H2 O2 production acts upstream of the xylem Na+ loading and is causally related to ROS-inducible Ca2+ uptake systems in the root stelar tissue. It was also found that ABA regulates (directly or indirectly) the process of Na+ retrieval from the xylem and the significant reduction of Na+ and K+ fluxes induced by bumetanide are indicative of a major role of chloride cation co-transporter (CCC) on xylem ion loading. Transcript levels of HvHKT1;5_like and HvSOS1_like genes in the root stele were observed to decrease after salt stress, while there was an increase in HvSKOR_like gene, indicating that these ion transporters are involved in primary Na+ /K+ movement into/out of xylem.

The c-Ski family member and transcriptional regulator Corl2/Skor2 promotes early differentiation of cerebellar Purkinje cells.

Purkinje cells (PCs) provide the primary output from the cerebellar cortex, which controls movement and posture, and loss of PCs causes severe cerebellar dysfunction. The mechanisms underlying cell fate determination and early differentiation of PC remain largely unknown. Here we show that the c-Ski family member and transcriptional regulator Corl2 is required for correct differentiation of PCs. In Corl2 knock-out embryos, initial PC specification appeared largely normal, but in a subset of presumptive PCs generated near the ventral border of the PC domain, cell fate choice was compromised and cells showed a mixed identity expressing the interneuron marker Pax2 as well. Additionally, selection and maintenance of the transmitter phenotype was compromised in most developing PCs in the mutants. During later differentiation steps, induction of PC marker genes was significantly suppressed, suggesting that maturation was delayed in the absence of Corl2. Consistently, defects in migration, cell polarization and dendrite formation were observed in mutant PCs, although their axonal trajectories appeared normal. These phenotypes closely resembled those of mutants for Rora, an essential regulator of PC differentiation. However, Rora expression was not significantly changed in the Corl2 mutants, indicating that Corl2 does not simply act upstream of Rora to promote PC differentiation. ChIP experiments revealed that Corl2 bound to the promoter regions of several PC-selective genes, which are also known to be direct downstream targets of RORα. Altogether, our results identified a novel regulatory program of PC differentiation involving Corl2, which might cooperate with the RORα pathway.

Human α-synuclein overexpression upregulates SKOR1 in a rat model of simulated nigrostriatal ageing.

Parkinson's disease (PD) is characterised by progressive loss of dopaminergic (DA) neurons from the substantia nigra (SN) and α-synuclein (αSyn) accumulation. Age is the biggest risk factor for PD and may create a vulnerable pre-parkinsonian state, but the drivers of this association are unclear. It is known that ageing increases αSyn expression in DA neurons and that this may alter molecular processes that are central to maintaining nigrostriatal integrity. To model this, adult female Sprague-Dawley rats received a unilateral intranigral injection of adeno-associated viral (AAV) vector carrying wild-type human αSyn (AAV-αSyn) or control vector (AAV-Null). AAV-αSyn induced no detrimental effects on motor behaviour, but there was expression of human wild-type αSyn throughout the midbrain and ipsilateral striatum at 20 weeks post-surgery. Microarray analysis revealed that the gene most-upregulated in the ipsilateral SN of the AAV-αSyn group was the SKI Family Transcriptional Corepressor 1 (SKOR1). Bioenergetic state analysis of mitochondrial function found that SKOR1 overexpression reduced the maximum rate of cellular respiration in SH-SY5Y cells. Furthermore, experiments in SH-SY5Y cells revealed that SKOR1 overexpression impaired neurite growth to the same extent as αSyn, and inhibited BMP-SMAD-dependent transcription, a pathway that promotes DA neuronal survival and growth. Given the normal influence of ageing on DA neuron loss in human SN, the extent of αSyn-induced SKOR1 expression may influence whether an individual undergoes normal nigrostriatal ageing or reaches a threshold for prodromal PD. This provides new insight into mechanisms through which ageing-related increases in αSyn may influence molecular mechanisms important for the maintenance of neuronal integrity.

Genome-wide identification of Shaker K+ channel family in Nicotiana tabacum and functional analysis of NtSKOR1B in response to salt stress.

Soil salinization poses a mounting global ecological and environmental threat. The identification of genes responsible for negative regulation of salt tolerance and their utilization in crop improvement through gene editing technologies emerges as a swift strategy for the effective utilization of saline-alkali lands. One efficient mechanism of plant salt tolerance is maintaining the proper intracellular K+/Na+ ratio. The Shaker K+ channels play a crucial role in potassium absorption, transport, and intracellular potassium homeostasis in plant cells. Here, the study presents the first genome-wide identification of Shaker K+ channels in Nicotiana tabacum L., along with a detailed bioinformatic analysis of the 20 identified members. Transcriptome analysis revealed a significant up-regulation of NtSKOR1B, an outwardly-rectifying member predominantly expressed in the root tissue of tobacco seedlings, in response to salt stress. This finding was then confirmed by GUS staining of ProNtSKOR1B::GUS transgenic lines and RT-qPCR analysis. Subsequently, NtSKOR1B knockout mutants (ntskor1) were then generated and subjected to salt conditions. It was found that ntskor1 mutants exhibit enhanced salt tolerance, characterized by increased biomass, higher K+ content and elevated K+/Na+ ratios in both leaf and root tissues, compared to wild-type plants. These results indicate that NtSKOR1B knockout inhibits K+ efflux in root and leaf tissues of tobacco seedlings under salt stress, thereby maintaining higher K+/Na+ ratios within the cells. Thus, our study identifies NtSKOR1B as a negative regulator of salt tolerance in tobacco seedlings.

Outward-rectifying potassium channels GORK and SKOR function in regulation of root growth under salt stress in Arabidopsis thaliana.

Plants often face high salinity as a significant environmental challenge with roots being the first responders to this stress. Maintaining K+/Na+ ratio within plant cells is crucial for survival, as the intracellular K+ level decreases and the intracellular Na+ level increases under saline conditions. However, knowledge about the molecular regulatory mechanisms of K+ loss in response to salt stress through outward-rectifying K+ channels in plants is largely unknown. In this study, we found that the Arabidopsis double mutant gorkskor, in which the GORK and SKOR genes are disrupted, showed an improved primary root growth under salt stress compared to wild-type (WT) and the gork and skor single-mutant plants. No significant differences in the sensitivity to mannitol stress between the WT and gorkskor mutant were observed. Accumulation of ROS induced by salt stress was reduced in the gorkskor roots. The gorkskor mutant seedlings had significantly higher K+ content, lower Na+ content, and a greater resultant K+/Na+ ratio than the WT under salt stress. Moreover, salt-stress-induced elevation of cytosolic free Ca2+ concentration was reduced in the gorkskor roots. Taken together, these results suggest that Arabidopsis Shaker-type outward-rectifying K+ channels GORK and SKOR may redundantly function in regulation of primary root growth under salt stress and are involved in not only the late-stage response (e.g. K+ leakage) but also the early response including ROS production and [Ca2+]cyt elevation.

Interactions among Merlin, Arkadia, and SKOR2 mediate NF2-associated Schwann cell proliferation in human.

NF2-Related Schwannomatosis (previously referred to as Neurofibromatosis Type 2, or NF2) is a genetic-associated disease resulting from mutations in the gene, NF2. NF2 encodes the merlin protein, which acts as a tumor suppressor. Bilateral vestibular schwannoma (VS) is a hallmark of NF2. Although the exactly molecular mechanism mediating NF2-driven schwannomatosis remain unclear, it is known that defective Merlin protein functionality leads to abnormal cell proliferation. Herein, we utilized a human induced pluripotent stem cell (hiPSC)-based Schwann cell (SC) model to investigate the role of merlin in human SCs. SCs were derived from hiPSCs carrying a NF2 mutation (c.191 T > C; p. L64P), its isogenic wild-type control cell line, and a NF2 patient-derived hiPSC line. NF2 mutant SCs showed abnormal cellular morphology and proliferation. Proteomic analyses identified novel interaction partners for Merlin - Arkadia and SKOR2. Our results established a new model in which merlin interacts with Arkadia and SKOR2 and this interaction is required for the proper activation of the SMAD-dependent pathway in TGFß signaling.

Xylem K+ loading modulates K+ and Cs+ absorption and distribution in Arabidopsis under K+-limited conditions.

Potassium (K+) is an essential macronutrient for plant growth. The transcriptional regulation of K+ transporter genes is one of the key mechanisms by which plants respond to K+ deficiency. Among the HAK/KUP/KT transporter family, HAK5, a high-affinity K+ transporter, is essential for root K+ uptake under low external K+ conditions. HAK5 expression in the root is highly induced by low external K+ concentration. While the molecular mechanisms of HAK5 regulation have been extensively studied, it remains unclear how plants sense and coordinates K+ uptake and translocation in response to changing environmental conditions. Using skor mutants, which have a defect in root-to-shoot K+ translocation, we have been able to determine how the internal K+ status affects the expression of HAK5. In skor mutant roots, under K+ deficiency, HAK5 expression was lower than in wild-type although the K+ concentration in roots was not significantly different. These results reveal that HAK5 is not only regulated by external K+ conditions but it is also regulated by internal K+ levels, which is in agreement with recent findings. Additionally, HAK5 plays a major role in the uptake of Cs+ in roots. Therefore, studying Cs+ in roots and having more detailed information about its uptake and translocation in the plant would be valuable. Radioactive tracing experiments revealed not only a reduction in the uptake of 137Cs+ and 42K+in skor mutants compared to wild-type but also a different distribution of 137Cs+ and 42K+ in tissues. In order to gain insight into the translocation, accumulation, and repartitioning of both K+ and Cs+ in plants, long-term treatment and split root experiments were conducted with the stable isotopes 133Cs+ and 85Rb+. Finally, our findings show that the K+ distribution in plant tissues regulates root uptake of K+ and Cs+ similarly, depending on HAK5; however, the translocation and accumulation of the two elements are different.

Molecular Analyses of V0v Spinal Interneurons and Identification of Transcriptional Regulators Downstream of Evx1 and Evx2 in these Cells.

Background: V0v spinal interneurons are highly conserved, glutamatergic, commissural neurons that function in locomotor circuits. We have previously shown that Evx1 and Evx2 are required to specify the neurotransmitter phenotype of these cells. However, we still know very little about the gene regulatory networks that act downstream of these transcription factors in V0v cells. Methods: To identify candidate members of V0v gene regulatory networks, we FAC-sorted WT and evx1;evx2 double mutant zebrafish V0v spinal interneurons and expression-profiled them using microarrays and single cell RNA-seq. We also used in situ hybridization to compare expression of a subset of candidate genes in evx1;evx2 double mutants and wild-type siblings. Results: Our data reveal two molecularly distinct subtypes of V0v spinal interneurons at 48 h and suggest that, by this stage of development, evx1;evx2 double mutant cells transfate into either inhibitory spinal interneurons, or motoneurons. Our results also identify 25 transcriptional regulator genes that require Evx1/2 for their expression in V0v interneurons, plus a further 11 transcriptional regulator genes that are repressed in V0v interneurons by Evx1/2. Two of the latter genes are hmx2 and hmx3a. Intriguingly, we show that Hmx2/3a, repress dI2 interneuronal expression of skor1a and nefma, two genes that require Evx1/2 for their expression in V0v interneurons. This suggests that Evx1/2 might regulate skor1a and nefma expression in V0v interneurons by repressing Hmx2/3a expression. Conclusions: This study identifies two molecularly distinct subsets of V0v spinal interneurons, as well as multiple transcriptional regulators that are strong candidates for acting downstream of Evx1/2 to specify the essential functional characteristics of these cells. Our data further suggest that in the absence of both Evx1 and Evx2, V0v spinal interneurons initially change their neurotransmitter phenotypes from excitatory to inhibitory and then, later, start to express markers of distinct types of inhibitory spinal interneurons, or motoneurons. Taken together, our findings significantly increase our knowledge of V0v and spinal development and move us closer towards the essential goal of identifying the complete gene regulatory networks that specify this crucial cell type.

Molecular analyses of zebrafish V0v spinal interneurons and identification of transcriptional regulators downstream of Evx1 and Evx2 in these cells.

BACKGROUND: V0v spinal interneurons are highly conserved, glutamatergic, commissural neurons that function in locomotor circuits. We have previously shown that Evx1 and Evx2 are required to specify the neurotransmitter phenotype of these cells. However, we still know very little about the gene regulatory networks that act downstream of these transcription factors in V0v cells. METHODS: To identify candidate members of V0v gene regulatory networks, we FAC-sorted wild-type and evx1;evx2 double mutant zebrafish V0v spinal interneurons and expression-profiled them using microarrays and single cell RNA-seq. We also used in situ hybridization to compare expression of a subset of candidate genes in evx1;evx2 double mutants and wild-type siblings. RESULTS: Our data reveal two molecularly distinct subtypes of zebrafish V0v spinal interneurons at 48 h and suggest that, by this stage of development, evx1;evx2 double mutant cells transfate into either inhibitory spinal interneurons, or motoneurons. Our results also identify 25 transcriptional regulator genes that require Evx1/2 for their expression in V0v interneurons, plus a further 11 transcriptional regulator genes that are repressed in V0v interneurons by Evx1/2. Two of the latter genes are hmx2 and hmx3a. Intriguingly, we show that Hmx2/3a, repress dI2 interneuron expression of skor1a and nefma, two genes that require Evx1/2 for their expression in V0v interneurons. This suggests that Evx1/2 might regulate skor1a and nefma expression in V0v interneurons by repressing Hmx2/3a expression. CONCLUSIONS: This study identifies two molecularly distinct subsets of zebrafish V0v spinal interneurons, as well as multiple transcriptional regulators that are strong candidates for acting downstream of Evx1/2 to specify the essential functional characteristics of these cells. Our data further suggest that in the absence of both Evx1 and Evx2, V0v spinal interneurons initially change their neurotransmitter phenotypes from excitatory to inhibitory and then, later, start to express markers of distinct types of inhibitory spinal interneurons, or motoneurons. Taken together, our findings significantly increase our knowledge of V0v and spinal development and move us closer towards the essential goal of identifying the complete gene regulatory networks that specify this crucial cell type.

New resources for the Drosophila 4th chromosome: FRT101F enabled mitotic clones and Bloom syndrome helicase enabled meiotic recombination.

Genes on the long arm of the Drosophila melanogaster 4th chromosome are difficult to study because the chromosome lacks mitotic and meiotic recombination. Without recombination numerous standard methods of genetic analysis are impossible. Here, we report new resources for the 4th. For mitotic recombination, we generated a chromosome with an FRT very near the centromere in 101F and a derivative that carries FRT101F with a distal ubiquitously expressed GAL80 transgene. This pair of chromosomes enables both unmarked and MARCM clones. For meiotic recombination, we demonstrate that a Bloom syndrome helicase and recombination defective double mutant genotype can create recombinant 4th chromosomes via female meiosis. All strains will be available to the community via the Bloomington Drosophila Stock Center. Additional resources for studies of the 4th are in preparation and will also be made available. The goal of the 4th Chromosome Resource Project is to accelerate the genetic analysis of protein-coding genes on the 4th, including the 44 genes with no demonstrated function. Studies of these previously inaccessible but largely conserved genes will close longstanding gaps in our knowledge of metazoan development and physiology.

Down regulation of transcripts involved in selective metabolic pathways as an acclimation strategy in nitrogen use efficient genotypes of rice under low nitrogen.

To understand the molecular mechanism of nitrogen use efficiency (NUE) in rice, two nitrogen (N) use efficient genotypes and two non-efficient genotypes were characterized using transcriptome analyses. The four genotypes were evaluated for 3 years under low and recommended N field conditions for 12 traits/parameters of yield, straw, nitrogen content along with NUE indices and 2 promising donors for rice NUE were identified. Using the transcriptome data generated from GS FLX 454 Roche and Illumina HiSeq 2000 of two efficient and two non-efficient genotypes grown under field conditions of low N and recommended N and their de novo assembly, differentially expressed transcripts and pathways during the panicle development were identified. Down regulation was observed in 30% of metabolic pathways in efficient genotypes and is being proposed as an acclimation strategy to low N. Ten sub metabolic pathways significantly enriched with additional transcripts either in the direction of the common expression or contra-regulated to the common expression were found to be critical for NUE in rice. Among the up-regulated transcripts in efficient genotypes, a hypothetical protein OsI_17904 with 2 alternative forms suggested the role of alternative splicing in NUE of rice and a potassium channel SKOR transcript (LOC_Os06g14030) has shown a positive correlation (0.62) with single plant yield under low N in a set of 16 rice genotypes. From the present study, we propose that the efficient genotypes appear to down regulate several not so critical metabolic pathways and divert the thus conserved energy to produce seed/yield under long-term N starvation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-020-02631-5.

Adult Movement Defects Associated with a CORL Mutation in Drosophila Display Behavioral Plasticity.

The CORL family of CNS-specific proteins share a Smad-binding region with mammalian SnoN and c-Ski protooncogenes. In this family Drosophila CORL has two mouse and two human relatives. Roles for the mouse and human CORL proteins are largely unknown. Based on genome-wide association studies linking the human CORL proteins Fussel15 and Fussel18 with ataxia, we tested the hypothesis that dCORL mutations will cause adult movement disorders. For our initial tests, we conducted side by side studies of adults with the small deletion Df(4)dCORL and eight control strains. We found that deletion mutants exhibit three types of behavioral plasticity. First, significant climbing defects attributable to loss of dCORL are eliminated by age. Second, significant phototaxis defects due to loss of dCORL are partially ameliorated by age and are not due to faulty photoreceptors. Third, Df(4)dCORL males raised in groups have a lower courtship index than males raised as singles though this defect is not due to loss of dCORL Subsequent tests showed that the climbing and phototaxis defects were phenocpied by dCORL21B and dCORL23C two CRISPR generated mutations. Overall, the finding that adult movement defects due to loss of dCORL are subject to age-dependent plasticity suggests new hypotheses for CORL functions in flies and mammals.

H2S pretreatment mitigates the alkaline salt stress on Malus hupehensis roots by regulating Na+/K+ homeostasis and oxidative stress.

Hydrogen sulfide (H2S) plays an important role in the plant salt stress response. The main component of salt stress is neutral salt (NaCl); NaHCO3 and Na2CO3 play a key role in soil alkaline due to the influence of pH. Malus hupehensis Rehd. var. pingyiensis Jiang (Pingyi Tiancha, PYTC) is a salt-sensitive apple rootstock. Seedlings of PYTC pretreated with NaHS (an H2S donor) were exposed to an alkaline salt solution, and then the plant growth, root architecture, oxidative damage, Na+/K+ homeostasis and gene expression of MhSOS1 and MhSKOR were investigated. The results showed that NaHS pretreatment increased the endogenous H2S content in seedlings, significantly alleviated the alkaline salt stress-induced growth inhibition and oxidative damage by inducing antioxidant enzymes activities, and sustained the root activity and root architecture of PYTC in the alkaline salt solution. NaHS pretreatment significantly decreased the root Na+ content and increased K+ content to maintain the homeostasis of Na+/K+, and effect the expression of MhSOS1 and MhSKOR at the transcription level in the presence of the alkaline salt. Our study reveals that application of H2S could mitigate the toxic effect of alkaline salt stress on Malus hupehensis seedlings, thus providing a foundation for improved plant tolerance to alkaline salt stress.

ABA-dependent K+ flux is one of the important features of the drought response that distinguishes Catalpa from two different habitats.

Abscisic acid (ABA)-induced stomatal closure can improve drought tolerance in higher plants. However, the relationship between ABA-related ion flux and improved drought resistance in the roots of woody plants is unclear. To investigate this relationship, we employed a noninvasive micro-test technique (NMT) to detect potassium (K+) flux in Catalpa fargesii and C. fargesii f. duclouxii after treatment with polyethylene glycol (PEG) and ABA. PEG treatment slightly increased the free proline content in both Catalpa species. However, simultaneous treatment with ABA and PEG resulted in a large increase in free proline content. Treatment with PEG led to a significant increase in K+ efflux, and both ABA and tetraethylammonium (TEA, a K+ channel inhibitor) blocked this efflux under short-term (1 d) and long-term (7 d) drought conditions. Furthermore, we detected SKOR (stelar K+ outward-rectifying channel) gene expression in roots, and the results showed that PEG significantly increased SKOR expression in C. fargesii f. duclouxii, but SKOR expression was inhibited by ABA in Catalpa fargesii. These findings indicate that ABA improves drought tolerance by inhibiting K+ efflux in Catalpa, but distinct ABA response patterns exist. Drought-tolerant species have better potassium retention are dependent on ABA, and can accumulate more proline than other species. SKOR is also ABA-dependent and sensitive to ABA, and K+ flux is a target of the ABA-mediated drought response.