The two title compounds comprise two acid molecules and one base molecule linked by O—H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit.
The crystal structures of title hydrogen-bonded co-crystals, 2C12H16O3·C12H10N2, (I), and 2C13H18O3·C12H10N2, (II), have been determined at 93 K. In (I), the asymmetric unit consists of one 4-(n-pentyloxy)benzoic acid molecule and one half-molecule of (E)-1,2-bis(pyridin-4-yl)ethene, which lies about an inversion centre. The asymmetric unit of (II) comprises two crystallographically independent 4-(n-hexyloxy)benzoic acid molecules and one 1,2-bis(pyridin-4-yl)ethene molecule. In each crystal, the acid and base components are linked by O—H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit of the acid and the base. The 2:1 units are linked via C—H⋯π and π–π interactions [centroid–centroid distances of 3.661 (2) and 3.909 (2) Å for (I), and 3.546 (2)–3.725 (4) Å for (II)], forming column structures. In (II), the base molecule is orientationally disordered over two sets of sites approximately around the N⋯N molecular axis, with an occupancy ratio of 0.647 (4):0.353 (4), and the average structure of the 2:1 unit adopts nearly pseudo-C
2 symmetry. Both compounds show liquid-crystal behaviour.
crystal structure; (E)-1,2-bis(pyridin-4-yl)ethene; 4-(n-pentyloxy)benzoic acid; 4-(n-hexyloxy)benzoic acid hydrogen-bonded liquid crystal
Crystal structures of four co-crystals of (E)-1,2-di(pyridin-4-yl)ethene with 4-alkoxybenzoic acids have been determined. Each compound comprises two acid molecules and one base molecule, which are held together by O—H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit.
The crystal structures of four hydrogen-bonded co-crystals of 4-alkoxybenzoic acid–(E)-1,2-di(pyridin-4-yl)ethene (2/1), namely, 2C8H8O3·C12H10N2, (I), 2C9H10O3·C12H10N2, (II), 2C10H12O3·C12H10N2, (III) and 2C11H14O3·C12H10N2, (IV), have been determined at 93 K. In compounds (I) and (IV), the asymmetric units are each composed of one 4-alkoxybenzoic acid molecule and one half-molecule of (E)-1,2-di(pyridin-4-yl)ethene, which lies on an inversion centre. The asymmetric unit of (II) consists of two crystallographically independent 4-ethoxybenzoic acid molecules and one 1,2-di(pyridin-4-yl)ethene molecule. Compound (III) crystallizes in a non-centrosymmetric space group (Pc) and the asymmetric unit comprises four 4-n-propoxybenzoic acid molecules and two (E)-1,2-di(pyridin-4-yl)ethane molecules. In each crystal, the acid and base components are linked by O—H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit of the acid and the base. In (I), (II) and (III), intermolecular C—H⋯O interactions are observed. The 2:1 units of (I) and (II) are linked via C—H⋯O hydrogen bonds, forming tape structures. In (III), the C—H⋯O hydrogen bonds, except for those formed in the units, link the two crystallographically independent 2:1 units. In (IV), no C—H⋯O interactions are observed, but π–π and C—H⋯π interactions link the units into a column structure.
crystal structure; (E)-1,2-di(pyridin-4-yl)ethene; 4-alkoxybenzoic acid; hydrogen-bonded liquid crystal
It is estimated that approximately 10% of pancreatic cancers have a familial component. Many inheritable genetic syndromes are associated with increased risk of pancreatic cancer, such as Peutz-Jeghers syndrome, hereditary breast-ovarian cancer and familial atypical multiple mole melanoma, but these conditions account for only a minority of familial pancreatic cancers. Previous studies have identified an increased prevalence of non-invasive precursor lesions, including pancreatic intraepithelial neoplasia, in the pancreata of patients with a strong family history of pancreatic cancer. A detailed investigation of the histopathology of invasive familial pancreatic cancer could provide insights into the mechanisms responsible for familial pancreatic cancer, as well as aid early detection and treatment strategies.
We have conducted a blinded review of the pathology of 519 familial and 651 sporadic pancreatic cancers within the National Familial Pancreas Tumor Registry. Patients with familial pancreatic cancer were defined as individuals from families in which at least a pair of first-degree relatives have been diagnosed with pancreatic cancer.
Overall, there were no statistically significant differences in histologic subtypes between familial and sporadic pancreatic cancers (p > 0.05). In addition, among surgical resection specimens within the study cohort, no statistically significant differences in mean tumor size, location, perineural invasion, angiolymphatic invasion, lymph node metastasis and pathologic stage were identified (p > 0.05).
Similar to sporadic pancreatic cancer, familial pancreatic cancer is morphologically and prognostically a heterogeneous disease.
Pancreatic cancer; familial; hereditary; pathology; morphology; histology
Crystal structures of three co-crystals of 1,2-bis(pyridin-4-yl)ethane with 4-alkoxybenzoic acids have been determined. The asymmetric unit of each compound comprises two crystallographically independent acid molecules and one base molecule, which are held together by O—H⋯N hydrogen bonds, forming linear hydrogen-bonded 2:1 units.
The crystal structures of three hydrogen-bonded co-crystals of 4-alkoxybenzoic acid–1,2-bis(pyridin-4-yl)ethane (2/1), namely, 2C9H10O3·C12H12N2, (I), 2C10H12O3·C12H12N2, (II), and 2C11H14O3·C12H12N2, (III), have been determined at 93, 290 and 93 K, respectively. In (I), the asymmetric unit consists of one 4-ethoxybenzoic acid molecule and one half-molecule of 1,2-bis(pyridin-4-yl)ethane, which lies on an inversion centre. In (II) and (III), the asymmetric units each comprise two crystallographically independent 4-alkoxybenzoic acid molecules and one 1,2-bis(pyridin-4-yl)ethane molecule. In each crystal, the two components are linked by O—H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1unit of the acid and the base. Similar to the structure of 2:1 unit of (I), the units of (II) and (III) adopt nearly pseudo-inversion symmetry. The 2:1 units of (I), (II) and (III) are linked via C—H⋯O hydrogen bonds, forming tape structures.
crystal structure; 1,2-bis(pyridin-4-yl)ethane; 4-alkoxybenzoic acid; hydrogen-bonded liquid crystal
Crystal structures of three co-crystals of bis(4-alkoxybenzoic acid) and 4,4′-bipyridyl have been determined at 93 K. The asymmetric unit of each compound comprises two crystallographically independent acid molecules and one base molecule, which are held together by O—H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit.
The crystal structures of three hydrogen-bonded co-crystals of 4-alkoxybenzoic acid–4,4′-bipyridyl (2/1), namely, 2C9H10O3·C10H8N2, (I), 2C10H12O3·C10H8N2, (II) and 2C11H14O3·C10H8N2, (III), have been determined at 93 K. Although the structure of (I) has been determined in the space group P21 with Z = 4 [Lai et al. (2008 ▸). J. Struct. Chem.
49, 1137–1140], the present study shows that the space group is P21/n with Z = 4. In each crystal, the components are linked by O—H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit of the acid and the base. The 2:1 unit of (I) adopts nearly pseudo-C
2 symmetry, viz. twofold rotation around an axis passing through the mid-point of the central C—C bond of 4,4′-bipyridyl, while the units of (II) and (III), except for the terminal alkyl chains, have pseudo-inversion symmetry. The 2:1 units of (I), (II) and (III) are linked via C—H⋯O hydrogen bonds, forming sheet, double-tape and tape structures, respectively.
crystal structure; 4,4′-bipyridyl; 4-alkoxybenzoic acid; hydrogen-bonded liquid crystal
Autophagy is an evolutionarily conserved process leading to the degradation of intracellular components in eukaryotes, which is important for nutrient recycling especially in response to starvation conditions. Nutrient recycling is an essential process that underpins productivity in crop plants, such that remobilized nitrogen derived from older organs supports the formation of new organs or grain-filling within a plant. We extended our understanding of autophagy in a model plant, Arabidopsis thaliana, to an important cereal, rice (Oryza sativa). Through analysis of transgenic rice plants stably expressing fluorescent marker proteins for autophagy or chloroplast stroma, we revealed that chloroplast proteins are partially degraded in the vacuole via Rubisco-containing bodies (RCBs), a type of autophagosomes containing stroma. We further reported evidence that the RCB pathway functions during natural leaf senescence to facilitate subsequent nitrogen remobilization into newly expanding leaves. Thus, our recent studies establish the importance of autophagy in biomass production of cereals.
autophagy; chloroplasts; crop plants; nitrogen remobilization; protein degradation; rice
Crystal structures of morpholinium hydrogen bromanilate have been determined at 130, 145 and 180 K. The asymmetric unit comprises one morpholinium cation and two halves of crystallographically independent bromanilate monoanions. The conformations of the two independent bromanilate anions are different from each other with respect to the O—H orientation. The two different anions are linked alternately into a chain though a short O—H⋯O hydrogen bond, in which the H atom is disordered over two positions.
Crystal structures of the title compound (systematic name: morpholin-4-ium 2,5-dibromo-4-hydroxy-3,6-dioxocyclohexa-1,4-dien-1-olate), C4H10NO+·C6HBr2O4
−, were determined at three temperatures, viz. 130, 145 and 180 K. The asymmetric unit comprises one morpholinium cation and two halves of crystallographically independent bromanilate monoanions, which are located on inversion centres. The conformations of the two independent bromanilate anions are different from each other with respect to the O—H orientation. In the crystal, the two different anions are linked alternately into a chain along  through a short O—H⋯O hydrogen bond, in which the H atom is disordered over two positions. The refined site-occupancy ratios, which are almost constant in the temperature range studied, are 0.49 (3):0.51 (3), 0.52 (3):0.48 (3) and 0.50 (3):0.50 (3), respectively, at 130, 145 and 180 K, and no significant difference in the molecular geometry and the molecular packing is observed at the three temperatures. The morpholinium cation links adjacent chains of anions via N—H⋯O hydrogen bonds, forming a sheet structure parallel to (-111).
crystal structure; bromanilic acid; morpholine; hydrogen-bonding; proton disorder
Early T-cell precursor-acute lymphoblastic leukemia (ETP-ALL) has been identified as a high-risk subtype of pediatric T-cell acute lymphoblastic leukemia (T-ALL). Conventional chemotherapy is not fully effective for this subtype of leukemia; therefore, potential therapeutic targets need to be explored. Analysis of the gene expression patterns of the transcription factors in pediatric T-ALL revealed that MEF2C and FLT3 were expressed at higher levels in ETP-ALL than typical T-ALL. Using human T-ALL and BaF3 cell lines with high expression levels of MEF2C, the present study tested whether the BCL2 inhibitor (ABT-737) restores the sensitivity to prednisolone (PSL), because MEF2C causes PSL resistance, possibly by augmenting the anti-apoptotic activity of BCL2. Treatment with PSL and ABT-737 caused a significant reduction in the IC50 of PSL in the MEF2C-expressing LOUCY cells, in addition to the MEF2C-transduced BaF3 cells, but not in the non-MEF2C-expressing Jurkat cells. The combination treatment significantly accelerated the killing of primary leukemic blast cells of ETP-ALL with high expression levels of MEF2C, which were co-cultured with murine stromal cells. These findings suggest that BCL2 inhibitors may be a therapeutic candidate in vivo for patients with ETP-ALL with high expression levels of MEF2C.
The structures of two isomeric compounds of isoquinoline with 3-chloro-2-nitrobenzoic acid and 4-chloro-2-nitrobenzoic acid have been determined at 190 K. In each compound, the acid and base molecules are held together by a short hydrogen bond between a carboxy O atom and a base N atom. In the hydrogen-bonded unit of the former, the H atom is disordered over two positions, while in the latter, an acid–base interaction involving H-atom transfer occurs and the H atom is located at the N site.
In each of the title isomeric compounds, C9H7.3N·C7H3.7ClNO4, (I), and C9H8N·C7H3ClNO4, (II), of isoquinoline with 3-chloro-2-nitrobenzoic acid and 4-chloro-2-nitrobenzoic acid, the two components are linked by a short hydrogen bond between a base N atom and a carboxy O atom. In the hydrogen-bonded unit of (I), the H atom is disordered over two positions with N and O site occupancies of 0.30 (3) and 0.70 (3), respectively, while in (II), an acid–base interaction involving H-atom transfer occurs and the H atom is located at the N site. In the crystal of (I), the acid–base units are connected through C—H⋯O hydrogen bonds into a tape structure along the b-axis direction. Inversion-related adjacent tapes are further linked through π–π interactions [centroid–centroid distances = 3.6389 (7)–3.7501 (7) Å], forming a layer parallel to (001). In the crystal of (II), the acid–base units are connected through C—H⋯O hydrogen bonds into a ladder structure along the a-axis direction. The ladders are further linked by another C—H⋯O hydrogen bond into a layer parallel to (001).
crystal structure; short hydrogen bond; chloro- and nitro-substituted benzoic acid; isoquinoline
It is unclear whether combined leg and arm high-intensity interval training (HIIT) improves fitness and morphological characteristics equal to those of leg-based HIIT programs. The aim of this study was to compare the effects of HIIT using leg-cycling (LC) and arm-cranking (AC) ergometers with an HIIT program using only LC. Effects on aerobic capacity and skeletal muscle were analyzed. Twelve healthy male subjects were assigned into two groups. One performed LC-HIIT (n=7) and the other LC- and AC-HIIT (n=5) twice weekly for 16 weeks. The training programs consisted of eight to 12 sets of >90% VO2 (the oxygen uptake that can be utilized in one minute) peak for 60 seconds with a 60-second active rest period. VO2 peak, watt peak, and heart rate were measured during an LC incremental exercise test. The cross-sectional area (CSA) of trunk and thigh muscles as well as bone-free lean body mass were measured using magnetic resonance imaging and dual-energy X-ray absorptiometry. The watt peak increased from baseline in both the LC (23%±38%; P<0.05) and the LC–AC groups (11%±9%; P<0.05). The CSA of the quadriceps femoris muscles also increased from baseline in both the LC (11%±4%; P<0.05) and the LC–AC groups (5%±5%; P<0.05). In contrast, increases were observed in the CSA of musculus psoas major (9%±11%) and musculus anterolateral abdominal (7%±4%) only in the LC–AC group. These results suggest that a combined LC- and AC-HIIT program improves aerobic capacity and muscle hypertrophy in both leg and trunk muscles.
arm-cranking ergometer; cycling ergometer; aerobic capacity; skeletal muscle
In flowering plants, the tapetum, the innermost layer of the anther, provides both nutrient and lipid components to developing microspores, pollen grains, and the pollen coat. Though the programmed cell death of the tapetum is one of the most critical and sensitive steps for fertility and is affected by various environmental stresses, its regulatory mechanisms remain mostly unknown. Here we show that autophagy is required for the metabolic regulation and nutrient supply in anthers and that autophagic degradation within tapetum cells is essential for postmeiotic anther development in rice. Autophagosome-like structures and several vacuole-enclosed lipid bodies were observed in postmeiotic tapetum cells specifically at the uninucleate stage during pollen development, which were completely abolished in a retrotransposon-insertional OsATG7 (autophagy-related 7)-knockout mutant defective in autophagy, suggesting that autophagy is induced in tapetum cells. Surprisingly, the mutant showed complete sporophytic male sterility, failed to accumulate lipidic and starch components in pollen grains at the flowering stage, showed reduced pollen germination activity, and had limited anther dehiscence. Lipidomic analyses suggested impairment of editing of phosphatidylcholines and lipid desaturation in the mutant during pollen maturation. These results indicate a critical involvement of autophagy in a reproductive developmental process of rice, and shed light on the novel autophagy-mediated regulation of lipid metabolism in eukaryotic cells.
anther; autophagy; male sterility; pollen development; rice
Autophagy is an intracellular process leading to vacuolar degradation of cytoplasmic components, which is important for nutrient recycling. Autophagic degradation of chloroplastic proteins via Rubisco-containing bodies is activated in leaves upon low sugar availability in Arabidopsis and our recent study reveals the contribution of autophagy to nighttime energy availability for growth. Whereas metabolic analysis supports that autophagic proteolysis provides a supply of alternative energy sources such as amino acids during sugar deficit, changes in a large number of metabolites due to autophagy deficiency are also observed. Here, we performed statistical characterization of that metabolic data. Principal component analysis clearly separated wild type and autophagy-deficient atg5 mutant samples, pointing to significant effects of autophagy deficiency on metabolite profiles in Arabidopsis leaves. Thirty-six and four metabolites were significantly increased and decreased in atg5 compared with wild type, respectively. These results imply that autophagic proteolysis is linked to plant metabolic processes.
Arabidopsis; autophagy; chloroplast; energy availability; metabolite profiling; Rubisco-containing body
In the title compound [systematic name: bis(4-methoxy-3,4-dihydroquinazolin-1-ium) 2,5-dichloro-3,6-dioxocyclohexa-1,4-diene-1,4-diolate], 2C9H11N2O+·C6Cl2O4
2−, the chloranilate anion lies about an inversion center. The 4-methoxy-3,4-dihydroquinazolin-1-ium cations are linked on both sides of the anion via bifurcated N—H⋯(O,O) and weak C—H⋯O hydrogen bonds, giving a centrosymmetric 2:1 aggregate. The 2:1 aggregates are linked by another N—H⋯O hydrogen bond into a tape running along [1-10]. The tapes are further linked by a C—H⋯O hydrogen bond into a layer parallel to the ab plane.
In the crystal structure of the title compound [systematic name: bis(triethylammonium) 2,5-dichloro-3,6-dioxocyclohexa-1,4-diene-1,4-diolate], 2C6H16N+·C6Cl2O4
2−, the chloranilate anion lies on an inversion center. The triethylammonium cations are linked on both sides of the anion via bifurcated N—H⋯(O,O) and weak C—H⋯O hydrogen bonds to give a centrosymmetric 2:1 aggregate. The 2:1 aggregates are further linked by C—H⋯O hydrogen bonds into a zigzag chain running along [01-1].
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
LC3; autolysosome; autophagosome; flux; lysosome; phagophore; stress; vacuole
In the title compound, C14H13ClN2O, the fused hydropyrimidine ring adopts an envelope conformation with one of the methylene C atoms at the flap. The three-membered ring is approximately perpendicular to the attached isoquinoline ring system, with a dihedral angle of 89.44 (11)°. In the crystal, molecules are linked by a weak C—H⋯π interaction, forming a helical chain along the c axis.
The asymmetric unit of the triclinic polymorph of the title compound (systematic name: 4-cyanopyridinium 2,5-dichloro-4-hydroxy-3,6-dioxocyclohexa-1,4-dien-1-olate), C6H5N2
−, consists of two crystallographically independent cation–anion units, in each of which the cation and the anion are linked by an N—H⋯O hydrogen bond. In the units, the dihedral angles between the cation and anion rings are 78.43 (11) and 80.71 (11)°. In the crystal, each unit independently forms a chain through N—H⋯O and O—H⋯N hydrogen bonds; one chain runs along the c axis while the other runs along . Weak C—H⋯O, C—H⋯N and C—H⋯Cl interactions are observed between the chains.
The asymmetric unit of the title compound, C13H9NO3, consists of two crystallographically independent molecules. In each molecule, the tetrahydrofuran (THF) ring adopts an envelope conformation with one of the methylene C atoms positioned at the flap. The dihedral angles between the mean plane of the THF and the benzofuran ring system are 70.85 (5) and 89.59 (6)°. In the crystal, molecules are stacked in a column along the a-axis direction through C—H⋯O hydrogen bonds, with columns further linked by C—H⋯N and C—H⋯O interactions.
Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit (RBCS) is encoded by a nuclear RBCS multigene family in many plant species. The contribution of the RBCS multigenes to accumulation of Rubisco holoenzyme and photosynthetic characteristics remains unclear. T-DNA insertion mutants of RBCS1A (rbcs1a-1) and RBCS3B (rbcs3b-1) were isolated among the four Arabidopsis RBCS genes, and a double mutant (rbcs1a3b-1) was generated. RBCS1A mRNA was not detected in rbcs1a-1 and rbcs1a3b-1, while the RBCS3B mRNA level was suppressed to ∼20% of the wild-type level in rbcs3b-1 and rbcs1a3b-1 leaves. As a result, total RBCS mRNA levels declined to 52, 79, and 23% of the wild-type level in rbcs1a-1, rbcs3b-1, and rbcs1a3b-1, respectively. Rubisco contents showed declines similar to total RBCS mRNA levels, and the ratio of Rubisco-nitrogen to total nitrogen was 62, 78, and 40% of the wild-type level in rbcs1a-1, rbcs3b-1, and rbcs1a3b-1, respectively. The effects of RBCS1A and RBCS3B mutations in rbcs1a3b-1 were clearly additive. The rates of CO2 assimilation at ambient CO2 of 40 Pa were reduced with decreased Rubisco contents in the respective mutant leaves. Although the RBCS composition in the Rubisco holoenzyme changed, the CO2 assimilation rates per unit of Rubisco content were the same irrespective of the genotype. These results clearly indicate that RBCS1A and RBCS3B contribute to accumulation of Rubisco in Arabidopsis leaves and that these genes work additively to yield sufficient Rubisco for photosynthetic capacity. It is also suggested that the RBCS composition in the Rubisco holoenzyme does not affect photosynthesis under the present ambient [CO2] conditions.
Arabidopsis; RbcL; RBCS multigene family; Rubisco
In the crystal structure of the title compound, C4H10NO+·C6HCl2O4
−·CH4O, the components are held together by bifurcated O—H⋯(O,O), O—H⋯(O,Cl) and N—H⋯(O,O) hydrogen bonds into a centrosymmetric 2+2+2 aggregate. The aggregates are further connected by another bifurcated N—H⋯(O, O) hydrogen bond, forming a double-tape structure along the b axis. A weak C—H⋯O interaction is observed between the tapes.
In the title co-crystal, 2C7H4ClNO4·C4H4N2, the pyrazine molecule is located on an inversion centre, so that the asymmetric unit consists of one molecule of 4-chloro-2-nitrobenzoic acid and a half-molecule of pyrazine. The components are connected by O—H⋯N and C—H⋯O hydrogen bonds, forming a 2:1 unit. In the hydrogen-bonded unit, the dihedral angle between the pyrazine ring and the benzene ring of the benzoic acid is 16.55 (4)°. The units are linked by intermolecular C—H⋯O hydrogen bonds, forming a sheet structure parallel to (04). A C—H⋯O hydrogen-bond linkage is also observed between these sheets.
Autophagy is an intracellular process for the vacuolar degradation of cytoplasmic components and is important for nutrient recycling during starvation. Chloroplasts can be partially mobilized to the vacuole by autophagy via spherical bodies named Rubisco-containing bodies (RCBs). Although chloroplasts contain approximately 80% of total leaf nitrogen and represent a major carbon and nitrogen source for recycling, the relationship between leaf nutrient status and RCB production remains unclear. We analyzed the effects of nutrient factors on the appearance of RCBs in Arabidopsis leaves and postulated that a close relationship exists between the autophagic degradation of chloroplasts via RCBs and leaf carbon status but not nitrogen status in autophagy. The importance of carbohydrates in RCB production during leaf senescence can be further argued. During nitrogen-limited senescence, as leaf carbohydrates were accumulated, RCB production was strongly suppressed. During the life span of leaves, RCB production increased with the progression of leaf expansion and senescence, while the production declined in late senescent leaves with a remarkable accumulation of carbohydrates, glucose and fructose. These results suggest that RCB production may be controlled by leaf carbon status during both induced and natural senescence.
arabidopsis (Arabidopsis thaliana); autophagy; chloroplast; nutrient response; leaf senescence; carbohydrate
In the title compound, C7H4ClNO4·C9H7N, the two components are connected by an O—H⋯N hydrogen bond. In the hydrogen-bonded unit, the dihedral angle between the quinoline ring system and the benzene ring of benzoic acid is 3.15 (7)°. In the crystal, units are linked by intermolecular C—H⋯O hydrogen bonds, forming a tape along the c axis. The tapes are stacked along the b axis through a C—H⋯O hydrogen bond into a layer parallel to the bc plane.
In the crystal structure of the title compound, C18H18O4, the full molecule is generated by the application of an inversion centre. The molecule is essentially planar, with an r.m.s. deviation of 0.017 (1) Å for all non-H atoms. The molecules are linked through intermolecular C—H⋯O interactions to form a molecular sheet parallel to the (02) plane.
The crystal structures of two solid phases of the title compound, C4H5N2
−·H2O, have been determined at 225 and 120 K. In the high-temperature phase, stable above 198 K, the transition temperature of which has been determined by 35Cl nuclear quadrupole resonance and differential thermal analysis measurements, the three components are held together by O—H⋯O, N⋯H⋯O, C—H⋯O and C—H⋯Cl hydrogen bonds, forming a centrosymmetric 2+2+2 aggregate. In the N⋯H⋯O hydrogen bond formed between the pyrimidin-1-ium cation and the water molecule, the H atom is disordered over two positions, resulting in two states, viz. pyrimidin-1-ium–water and pyrimidine–oxonium. In the low-temperature phase, the title compound crystallizes in the same monoclinic space group and has a similar molecular packing, but the 2+2+2 aggregate loses the centrosymmetry, resulting in a doubling of the unit cell and two crystallographically independent molecules for each component in the asymmetric unit. The H atom in one N⋯H⋯O hydrogen bond between the pyrimidin-1-ium cation and the water molecule is disordered, while the H atom in the other hydrogen bond is found to be ordered at the N-atom site with a long N—H distance [1.10 (3) Å].