Implementation of CsLIS/NES in linalool biosynthesis involves transcript splicing regulation in Camellia sinensis.

Volatile terpenoids produced in tea plants (Camellia sinensis) are airborne signals interacting against other ecosystem members, but also pleasant odorants of tea products. Transcription regulation (including transcript processing) is pivotal for plant volatile terpenoid production. In this study, a terpene synthase gene CsLIS/NES was recovered from tea plants (C. sinensis cv. "Long-Men Xiang"). CsLIS/NES transcription regulation resulted in 2 splicing forms: CsLIS/NES-1 and CsLIS/NES-2 lacking a 305 bp-fragment at N-terminus, both producing (E)-nerolidol and linalool in vitro. Transgenic tobacco studies and a gene-specific antisense oligo-deoxynucleotide suppression applied in tea leaves indicated that CsLIS/NES-1, localized in chloroplasts, acted as linalool synthase, whereas CsLIS/NES-2 localized in cytosol, functioned as a potential nerolidol synthase, but not linalool synthase. Expression patterns of the 2 transcript isoforms in tea were distinctly different and responded differentially to the application of stress signal molecule methyl jasmonate. Leaf expression of CsLIS/NES-1, but not CsLIS/NES-2, was significantly induced by methyl jasmonate. Our data indicated that distinct transcript splicing regulation patterns, together with subcellular compartmentation of CsLIS/NE-1 and CsLIS/NE-2 implemented the linalool biosynthesis regulation in tea plants in responding to endogenous and exogenous regulatory factors.

Arabidopsis mutant sk156 reveals complex regulation of SPL15 in a miR156-controlled gene network.

BACKGROUND: The Arabidopsis microRNA156 (miR156) regulates 11 members of the SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) family by base pairing to complementary target mRNAs. Each SPL gene further regulates a set of other genes; thus, miR156 controls numerous genes through a complex gene regulation network. Increased axillary branching occurs in transgenic Arabidopsis overexpressing miR156b, similar to that observed in loss-of-function max3 and max4 mutants with lesions in carotenoid cleavage dioxygenases. Arabidopsis miR156b was found to enhance carotenoid levels and reproductive shoot branching when expressed in Brassica napus, suggesting a link between miR156b expression and carotenoid metabolism. However, details of the miR156 regulatory network of SPL genes related to carotenoid metabolism are not known. RESULTS: In this study, an Arabidopsis T-DNA enhancer mutant, sk156, was identified due to its altered branching and trichome morphology and increased seed carotenoid levels compared to wild type (WT) ecovar Columbia. Enhanced miR156b expression due to the 35S enhancers present on the T-DNA insert was responsible for these phenotypes. Constitutive and leaf primodium-specific expression of a miR156-insensitive (mutated) SPL15 (SPL15m) largely restored WT seed carotenoid levels and plant morphology when expressed in sk156. The Arabidopsis native miR156-sensitive SPL15 (SPL15n) and SPL15m driven by a native SPL15 promoter did not restore the WT phenotype in sk156. Our findings suggest that SPL15 function is somewhat redundant with other SPL family members, which collectively affect plant phenotypes. Moreover, substantially decreased miR156b transcript levels in sk156 expressing SPL15m, together with the presence of multiple repeats of SPL-binding GTAC core sequence close to the miR156b transcription start site, suggested feedback regulation of miR156b expression by SPL15. This was supported by the demonstration of specific in vitro interaction between DNA-binding SBP domain of SPL15 and the proximal promoter sequence of miR156b. CONCLUSIONS: Enhanced miR156b expression in sk156 leads to the mutant phenotype including carotenoid levels in the seed through suppression of SPL15 and other SPL target genes. Moreover, SPL15 has a regulatory role not only for downstream components, but also for its own upstream regulator miR156b.

Effects of a coumarin derivative, 4-methylumbelliferone, on seed germination and seedling establishment in Arabidopsis.

The root system is central for plant adaptation to soil heterogeneity and is organized primarily by root branching. To search for compounds that regulate root branching, a forward chemical genetics screen was employed, and 4-methylumbelliferone (4-MU), a coumarin derivative, was found to be a potent regulator of lateral root formation. Exogenous application of 4-MU to Arabidopsis thaliana seeds affected germination and led to reduced primary root growth, the formation of bulbous root hairs, and irregular detached root caps accompanied by reorganization of the actin cytoskeleton in root tips before seedling establishment. Abundant lateral roots formed after exposure to 125 µM 4-MU for 22 days. Molecular, biochemical, and phytochemical approaches were used to determine the effect of 4-MU on root growth and root branching. Arabidopsis seedlings grown in the presence of 4-MU accumulated this compound only in roots, where it was partially transformed by UDP-glycosyltransferases (UGTs) into 4-methylumbelliferyl-ß-D-glucoside (4-MU-Glc). The presence of 4-MU-Glc in seedling roots was consistent with the upregulation of several genes that encode UGTs in the roots. This shows that UGTs play an integral role in the detoxification of 4-MU in plants. The increased expression of two auxin efflux facilitator genes (PIN2 and PIN3) in response to 4-MU and the lack of response of the auxin receptor TIR1 and the key auxin biosynthetic gene YUCCA1 suggest that auxin redistribution, rather than auxin biosynthesis, may directly or indirectly mediate 4-MU-induced root branching.

Metabolic engineering of isoflavone genistein in Brassica napus with soybean isoflavone synthase.

Genistein, 4',5,7-trihydroxyisoflavone, is an isoflavonoid compound predominantly restricted to legumes and known to possess phyto-oestrogenic and antioxidative activities. The key enzyme that redirects phenylpropanoid pathway intermediates from flavonoids to isoflavonoids is the isoflavone synthase (IFS). Brassica napus is a non-legume oilseed crop with vegetative tissues producing phenylpropanoids and flavonoids, but does not naturally accumulate isoflavones due to the absence of IFS. To demonstrate whether exogenous IFS is able to use endogenous substrate to produce isoflavone genistein in oilseed crop, the soybean IFS gene (GmIFS2) was incorporated into B. napus plants. The presence of GmIFS2 in B. napus was shown to direct the synthesis and accumulation of genistein derivatives in leaves up to 0.72 mg g(-1) DW. In addition, expression levels for most B. napus genes in the phenylpropanoid pathway were altered. These results suggest that the heterologous GmIFS2 enzyme is functionally active at using the B. napus naringenin as a substrate to produce genistein in oilseed rape.

Cloning and functional characterization of a chalcone isomerase from Trigonella foenum-graecum L.

Flavonoids belong to a group of plant natural products with variable phenolic structures and play important roles in protection against biotic and abiotic stress. Fenugreek (Trigonella foenum-graecum L.) seeds and stems contain flavonol glycosides and isoflavone derivatives. Up to now, the molecular features of fenugreek flavonoid biosynthesis have not been characterized. Here we present cloning of a cDNA encoding a chalcone isomerase (namely TFGCHI-1) from the leaves of T. foenum-graecum which convert chalcones to flavanones in vitro. Transformation of Arabidopsis loss-of-function TT5 (CHI) mutant with a TFGCHI-1 cDNA complemented TT5 and produced higher levels of flavonol glycosides than wild-type Col-0.

Effects of the timing of laparoscopic cholecystectomy after endoscopic retrograde cholangiopancreatography on liver, bile, and inflammatory indices and cholecysto-choledocholithiasis patient prognoses.

OBJECTIVES: This study explored the effects of the timing of laparoscopic cholecystectomy (LC) after endoscopic retrograde cholangiopancreatography (ERCP) on liver function, bile biochemical indices, inflammatory reactions, and cholecysto-choledocholithiasis patient prognoses. METHODS: A total of 103 cholecysto-choledocholithiasis patients were stratified into control (CG; n=51; LC at 4-7 d after ERCP) and observation groups (OG; n=52; LC at 1-3 d after ERCP) using a random number table. RESULTS: The surgical time was shorter and intraoperative blood loss was less in OG than in CG, and the two groups were not statistically different in terms of time to the first passage of gas through anus, length of postoperative hospital stay, conversion rate to laparotomy, and stone-free rate. Four weeks after LC, alanine aminotransferase (ALT), total bilirubin (TBil), albumin (ALB), and glutamyl transpeptidase (GGT) levels declined in both groups, but the difference was not statistically significant. Three days after LC, total bile acid (TBA) levels increased, and cholesterol (CHO), unconjugated bilirubin (UCB), and TBiL levels were reduced in both groups, but were not statistically different (p>0.05). Three days after LC, interleukin (IL)-6, procalcitonin (PCT), and high-sensitivity C-reactive protein (hs-CRP) levels in the serum and bile increased in both groups and were lower in OG. The total incidence of perioperative complications was 1.92% in OG, which was lower than 15.69% in the CG. CONCLUSION: For cholecysto-choledocholithiasis patients, LC at 1-3 d after ERCP can shorten surgical times, reduce intraoperative blood loss, improve liver function and bile biochemistry, relieve inflammatory reactions, reduce complications, and improve prognoses.

Prognostic significance of preoperative platelet-lymphocyte ratio in a Chinese cohort patient with colorectal cancer.

Cancer-related systemic inflammation affects many aspects of malignancy. The platelet-to-lymphocyte ratio (PLR), an easily applicable inflammatory marker based on platelet and lymphocyte counts, is associated with the clinical outcome of some cancers. The present study aimed to investigate the prognostic significance of the preoperative PLR in a cohort of colorectal cancer (CRC) patients. A total of 138 patients with CRC were enrolled in this retrospective study. The optimal cutoff value for the PLR was calculated using receiver operating curve (ROC) analysis. The correlation of PLR with the clinicopathological characteristics of patients was explored. Cox proportional hazard analysis was applied to determine the independent prognostic effect of PLR. PLR of 248 yielded the most optimal predictive value for the prognosis of CRC [area under the curve (AUC) = 0.820]. High level of PLR was significantly associated with lymph node and distance metastasis (P<0.001 and = 0.003, respectively), vascular and perinural invasion (P<0.001), advanced TNM stage (P<0.001), and poor differentiation (P = 0.037). Furthermore, the univariable analysis showed a significant impact of increased PLR on OS (HR = 4.326, 95% CI: 2.903-6.445, P<0.001), while this association remained significant in multivariable analysis (adjusted HR = 4.605, 95% CI: 2.786-7.611, P<0.001). Our findings indicated that elevated preoperative PLR might have potential value in predicting poor outcome in patients with CRC.

Data on green tea flavor determinantes as affected by cultivars and manufacturing processes.

This paper presents data related to an article entitled "Green tea flavor determinants and their changes over manufacturing processes" (Han et al., 2016) [1]. Green tea samples were prepared with steaming and pan firing treatments from the tender leaves of tea cultivars 'Bai-Sang Cha' ('BAS') and 'Fuding-Dabai Cha' ('FUD'). Aroma compounds from the tea infusions were detected and quantified using HS-SPME coupled with GC/MS. Sensory evaluation was also made for characteristic tea flavor. The data shows the abundances of the detected aroma compounds, their threshold values and odor characteristics in the two differently processed tea samples as well as two different cultivars.

Metabolic Flux Redirection and Transcriptomic Reprogramming in the Albino Tea Cultivar 'Yu-Jin-Xiang' with an Emphasis on Catechin Production.

In this study, shade-induced conversion from a young pale/yellow leaf phenotype to a green leaf phenotype was studied using metabolic and transcriptomic profiling and the albino cultivar 'Yu-Jin-Xiang' ('YJX') of Camellia sinensis for a better understanding of mechanisms underlying the phenotype shift and the altered catechin and theanine production. Shaded leaf greening resulted from an increase in leaf chlorophyll and carotenoid abundance and chloroplast development. A total of 1,196 differentially expressed genes (DEGs) were identified between the 'YJX' pale and shaded green leaves, and these DEGs affected 'chloroplast organization' and 'response to high light' besides many other biological processes and pathways. Metabolic flux redirection and transcriptomic reprogramming were found in flavonoid and carotenoid pathways of the 'YJX' pale leaves and shaded green leaves to different extents compared to the green cultivar 'Shu-Cha-Zao'. Enhanced production of the antioxidant quercetin rather than catechin biosynthesis was correlated positively with the enhanced transcription of FLAVONOL SYNTHASE and FLAVANONE/FLAVONOL HYDROXYLASES leading to quercetin accumulation and negatively correlated to suppressed LEUCOANTHOCYANIDIN REDUCTASE, ANTHOCYANIDIN REDUCTASE and SYNTHASE leading to catechin biosynthesis. The altered levels of quercetin and catechins in 'YJX' will impact on its tea flavor and health benefits.

Effects of the timing of laparoscopic cholecystectomy after endoscopic retrograde cholangiopancreatography on liver, bile, and inflammatory indices and cholecysto-choledocholithiasis patient prognoses

OBJECTIVES: This study explored the effects of the timing of laparoscopic cholecystectomy (LC) after endoscopic retrograde cholangiopancreatography (ERCP) on liver function, bile biochemical indices, inflammatory reactions, and cholecysto-choledocholithiasis patient prognoses. METHODS: A total of 103 cholecysto-choledocholithiasis patients were stratified into control (CG; n=51; LC at 4-7 d after ERCP) and observation groups (OG; n=52; LC at 1-3 d after ERCP) using a random number table. RESULTS: The surgical time was shorter and intraoperative blood loss was less in OG than in CG, and the two groups were not statistically different in terms of time to the first passage of gas through anus, length of postoperative hospital stay, conversion rate to laparotomy, and stone-free rate. Four weeks after LC, alanine aminotransferase (ALT), total bilirubin (TBil), albumin (ALB), and glutamyl transpeptidase (GGT) levels declined in both groups, but the difference was not statistically significant. Three days after LC, total bile acid (TBA) levels increased, and cholesterol (CHO), unconjugated bilirubin (UCB), and TBiL levels were reduced in both groups, but were not statistically different (p>0.05). Three days after LC, interleukin (IL)-6, procalcitonin (PCT), and high-sensitivity C-reactive protein (hs-CRP) levels in the serum and bile increased in both groups and were lower in OG. The total incidence of perioperative complications was 1.92% in OG, which was lower than 15.69% in the CG. CONCLUSION: For cholecysto-choledocholithiasis patients, LC at 1-3 d after ERCP can shorten surgical times, reduce intraoperative blood loss, improve liver function and bile biochemistry, relieve inflammatory reactions, reduce complications, and improve prognoses.

Green tea flavour determinants and their changes over manufacturing processes.

Flavour determinants in tea infusions and their changes during manufacturing processes were studied using Camellia sinensis cultivars 'Bai-Sang Cha' ('BAS') possessing significant floral scents and 'Fuding-Dabai Cha' ('FUD') with common green tea odour. Metabolite profiling based on odour activity threshold revealed that 'BAS' contained higher levels of the active odorants ß-ionone, linalool and its two oxides, geraniol, epoxylinalool, decanal and taste determinant catechins than 'FUD' (p<0.05). Enhanced transcription of some terpenoid and catechin biosynthetic genes in 'BAS' suggested genetically enhanced production of those flavour compounds. Due to manufacturing processes, the levels of linalool and geraniol decreased whereas those of ß-ionone, linalool oxides, indole and cis-jasmone increased. Compared with pan-fire treatment, steam treatment reduced the levels of catechins and proportion of geraniol, linalool and its derivatives, consequently, reducing catechin-related astringency and monoterpenol-related floral scent. Our study suggests that flavour determinant targeted modulation could be made through genotype and manufacturing improvements.

SCARECROW-LIKE15 interacts with HISTONE DEACETYLASE19 and is essential for repressing the seed maturation programme.

Epigenetic regulation of gene expression is critical for controlling embryonic properties during the embryo-to-seedling phase transition. Here we report that a histone deacetylase19 (HDA19)-associated regulator, scarecrow-like15 (SCL15), is essential for repressing the seed maturation programme in vegetative tissues. SCL15 is expressed in and GFP-tagged SCL15 predominantly localizes to, the vascular bundles particularly in the phloem companion cells and neighbouring specialized cells. Mutation of SCL15 leads to a global shift in gene expression in seedlings to a profile resembling late embryogenesis in seeds. In scl15 seedlings, many genes involved in seed maturation are markedly derepressed with concomitant accumulation of seed 12S globulin; this is correlated with elevated levels of histone acetylation at a subset of seed-specific loci. SCL15 physically interacts with HDA19 and direct targets of HDA19-SCL15 association are identified. These studies reveal that SCL15 acts as an HDA19-associated regulator to repress embryonic traits in seedlings.

Determination of quality constituents in the young leaves of albino tea cultivars.

Albino tea has received increased attention due to its brisk flavour. To identify changes in the key chemical constituents conveying important qualities to albino tea, the metabolite profiles of four albino cultivars and one green tea cultivar were analysed. Compared to the green tea control, significantly decreased contents of chlorophyll (Chl) (p<0.01), total carotenoids (p<0.05), caffeine (p<0.01), and total catechins (p<0.05) were found in albino tea leaves with a few exceptions, whereas increases were noted in the Chl a/b ratio and the contents of both zeaxanthin and free amino acids, including theanine. Multivariate analysis identified catechins and carotenoids as the most important contributors to the metabolic profile variance between the albino and green tea cultivars. High levels of amino acids, along with low levels of chlorophylls, catechins and caffeine, contribute to the qualities of albino tea, which include reduced astringency and bitterness, along with a strong umami taste.

Modulation of root branching by a coumarin derivative.

A healthy root system is crucial to plant growth and survival. To maintain efficiency of root function, plants have to dynamically modulate root system architecture through various adaptive mechanisms such as lateral root formation to respond to a changing and diversified soil environment. Exogenous application of a coumarin derivative, 4-methylumbelliferone (4-MU), in Arabidopsis thaliana inhibits seed germination by mainly reducing primary root growth. UDP-glycosyltransferases play an integral role in the biochemical mechanism of 4-MU detoxification in plant roots.1 However, 4-MU treatment also dramatically led to increased lateral root initiation, elongation and density. Moreover, marked root bending at the root-hypocotyl junction and auxin redistribution appeared to contribute to the 4-MU-mediated lateral root formation. We propose that 4-MU would serve as a useful chemical tool to study auxin-mediated root branching.

ASIL1 is required for proper timing of seed filling in Arabidopsis.

In flowering plants, seed development and seed filling are intricate genetically programmed processes that correlate with changes in metabolite levels and that are spatially and temporally regulated by a complex signaling network mediated mainly by sugars and hormones. ASIL1, a member of the plant-specific trihelix family of DNA-binding transcription factors, was isolated based on its interaction with the GT-element of the Arabidopsis thaliana 2S albumin At2S3 promoter. Mutation of ASIL1 derepressed expression of a subset of embryonic genes resulting in accumulation of 2S albumin and embryo-specific lipids in leaves. It was recently reported that mutation of ASIL1 led to early embryo development in Arabidopsis. In this study, we demonstrated that ASIL1 acts as a temporal regulator of seed filling. In developing siliques, mutation of ASIL1 led to earlier expression of master regulatory genes LEC2, FUS3 and ABI3 as well as genes for seed storage reserves. Moreover, the 12S globulin accumulated to a much higher level in the developing seeds of asil1-1 compared to wild type. To our knowledge, this is the first evidence that ASIL1 not only functions as a negative regulator of embryonic traits in seedlings but also contributes to the maintenance of precise temporal control of seed filling. Thus, ASIL1 represents a novel component of the regulatory framework controlling embryonic gene expression in Arabidopsis.

Purple canola: Arabidopsis PAP1 increases antioxidants and phenolics in Brassica napus leaves.

Anthocyanins, other flavonoids, and phenolic acids belong to a group of plant natural products with antioxidant activity and may play important roles in plant protection against biotic and abiotic stress and in protection against human diseases. In the present study, the Arabidopsis regulatory gene Production of Anthocyanin Pigment 1 (AtPAP1) was expressed in Brassica napus (canola), and its presence enhanced the antioxidant capacity in transgenic leaves up to 4-fold. Transgenic plants had intense purple coloration, cyanidin and pelargonidin levels were enhanced 50-fold, and quercetin and sinapic acid were 5-fold higher. Consistent with these phytochemical and biological changes, expression for most genes in the flavonoid and phenolic acid biosynthetic pathways was also stimulated.

Plasma membrane localization and potential endocytosis of constitutively expressed XA21 proteins in transgenic rice.

The rice pattern recognition receptor (PRR) XA21 confers race-specific resistance in leaf infection by bacterial blight Xathomonas oryzae pv. oryzae (Xoo), and was shown to be primarily localized to the endoplasmic reticulum (ER) when expressed with its native promoter or overexpressed in the protoplast. However, whether the protein is still ER-localization in the intact cell when overexpressed remains to be identified. Here, we showed that XA21, its kinase-dead mutant XA21P(K736EP), and the triple autophosphorylation mutant XA21P(S686A/T688A/S699A) GFP fusions were primarily localized to the plasma membrane (PM) when overexpressed in the intact transgenic rice cell, and also localized to the ER in the transgenic protoplast. The transgenic plants constitutively expressing the wild-type XA21 or its GFP fusion displayed race-specific resistance to Xoo at the adult and seedling stages. XA21 and XA21P(K736EP) could be internalized probably via the SCAMP-positive early endosomal compartment in the protoplast, suggesting that XA21 might be endocytosed to initiate resistance responses during pathogen infection. We also established a root infection system and demonstrated that XA21 also mediated race-specific resistance responses to Xoo in the root. Our current study provides an insight into the nature of the XA21-mediated resistance and a practical approach using the root cell system to further dissect the cellular signaling of the PRR during the rice-Xoo interaction.

Repression of seed maturation genes by a trihelix transcriptional repressor in Arabidopsis seedlings.

The seed maturation program is repressed during germination and seedling development so that embryonic genes are not expressed in vegetative organs. Here, we describe a regulator that represses the expression of embryonic seed maturation genes in vegetative tissues. ASIL1 (for Arabidopsis 6b-interacting protein 1-like 1) was isolated by its interaction with the Arabidopsis thaliana 2S3 promoter. ASIL1 possesses domains conserved in the plant-specific trihelix family of DNA binding proteins and belongs to a subfamily of 6b-interacting protein 1-like factors. The seedlings of asil1 mutants exhibited a global shift in gene expression to a profile resembling late embryogenesis. LEAFY COTYLEDON1 and 2 were markedly derepressed during early germination, as was a large subset of seed maturation genes, such as those encoding seed storage proteins and oleosins, in seedlings of asil1 mutants. Consistent with this, asil1 seedlings accumulated 2S albumin and oil with a fatty acid composition similar to that of seed-derived lipid. Moreover, ASIL1 specifically recognized a GT element that overlaps the G-box and is in close proximity to the RY repeats of the 2S promoters. We suggest that ASIL1 targets GT-box-containing embryonic genes by competing with the binding of transcriptional activators to this promoter region.

Isolation and characterization of a GCN5-interacting protein from Arabidopsis thaliana.

An Arabidopsis protein, AtEML, was isolated based on its interaction with the histone acetyltransferase AtGCN5 in a yeast two-hybrid screen. RNA blot and RT-PCR analysis showed that AtEML is expressed in flowers, leaves, stems and siliques. The promoter region of AtEML has several cis-acting elements associated with response to biotic and abiotic stress conditions, and the accumulation of the AtEML transcript was found to be regulated by cold and salt treatments. In vitro and in vivo protein-protein interaction assays indicated that AtEML interacts with AtGCN5 through the N-terminal region. Furthermore, AtEML was shown to activate expression of the lacZ reporter gene in yeast through recruitment of AtGCN5. Such recruitment was accompanied by an increase in histone H3 acetylation at the promoter driving lacZ expression, as determined by chromatin immunoprecipitation. A higher level of AtEML gene expression was detected in the Arabidopsis gcn5 knockout mutant as compared to wild type Arabidopsis, indicating that AtEML expression is regulated by AtGCN5. These results suggest that AtEML may be a transcription factor that co-ordinates the expression of target stress regulated genes through involvement in recruiting AtGCN5 to their promoters.

An auxin-responsive SCARECROW-like transcriptional activator interacts with histone deacetylase.

Members of the plant-specific GRAS family of putative transcription factors are involved in various aspects of plant development. SCARECROW (SCR) is a member of this protein family and plays a significant role in the radial patterning of both roots and shoots. However, little is known about the regulation of SCR expression and its mode of action in plants. Here, we report on the isolation and characterization of a Brassica napus SCARECROW-like protein, BnSCL1, isolated by selecting for proteins that interact with the Arabidopsis histone deacetylase AtHDA19 in a yeast two-hybrid screen. BnSCL1 contains domains conserved in the GRAS family of proteins, interacts with AtHDA19 through a VHIID domain, and exerts transcription activation of reporter genes . BnSCL1 is expressed predominantly in the roots, where its expression is regulated by auxin, as it also is in shoots and mature leaves. These results indicate that BnSCL1 is a member of the GRAS family, and suggest that its mode of action in plant auxin response may involve interaction with HDA19.