3-(4-Methyl-3-pentenyl)-2(5H)-furanone, alpha,alpha-acariolide and 4-(4-methyl-3-pentenyl)-2(5H)-furanone, alpha,beta-acariolide: new monoterpene lactones from the astigmatid mites, Schwiebea araujoae and Rhizoglyphus sp. (Astigmata: Acaridae)

A new monoterpene lactone from the acarid mite, Schwiebea araujoae, was elucidated without its isolation by GC/FT-IR and GC/MS analyses to be 3-(4-methyl-3-pentenyl)-2(5H)-furanone (1) and tentatively named as alpha,alpha-acariolide. The structure of 1 was identified by its synthesis from alpha-bromo-gamma-butyrolactone via 4 reaction steps. The synthesized compound gave the same GC/MS and GC/FT-IR spectra as those of the natural product. The other monoterpene lactone was likewise elucidated from the unidentified Rhizoglyphus mite to be 4-(4-methyl-3-pentenyl)-2(5H)-furanone (2) and named as alpha,beta-acariolide; it was also identified by its synthesis in 5 reaction steps from the same butyrolactone as the starting material. GC/MS and GC/FT-IR spectra of the preparation were identical to those of the natural product.     

Cell division and cell enlargement in isolated Cucurbita cotyledons grown in darkness and in light

The spatial and temporal patterns of post-embryonal cell growth and cell division were characterised in excised cotyledons of vegetable marrow (Cucurbita pepo L. var. giromontia Alef.) incubated in water. The concurrent roles of these two processes in cotyledon growth were determined using paradermal sections of the first palisade layer of developing cotyledons. Tissue specificity was observed in the pattern of cell division. The daughter cells derived from an initial cell, which had already differentiated before imbibition of the seeds, were tightly packed in a cluster, which enabled us to monitor cell division during early cotyledon development. Heterogeneity of cell size was recognised during the process of cell proliferation in the cluster, suggesting that cell division is uncoupled from control of cell size. There was significantly more cell division in the marginal part of the cotyledons than in other parts, suggesting high activity of the marginal meristem. Light enhanced cell and cotyledon enlargement, but had no effect on the number of divisions. This study elucidated the cellular basis of post-germinative Cucurbita cotyledon morphogenesis and development. Electronic Publication     

Gas-phase disproportionation of nitric oxide at elevated pressures

T.P. Melia's chemical kinetics study of the disproportionation of nitric oxide (NO), 3NO →NO₂ + N₂O , (Melia, T.P. (1965) J. Inorg. Nucl. Chem., 27, 95-98), which is the most quoted quantitative investigation presently available, revealed a rather strong dependence of the effective rate constant, Kk ', of Melia's third-order rate law,- d[NO]/d t = Kk'[NO]₃, on the initial pressure of NO. In order to estimate extent of accumulation of NO₂ and N₂O as a function of time by integration of the rate law, we have evaluated the dependence of the effective rate constant as a function of pressure and thus as a function of time on the basis of the non-ideality of NO gas. Although our approach is crude in that the non-idealities of NO₂ and N₂O and other NO_x products and a probable deviation of the gas mixture from the Dalton's law have not been considered, it provides a means for approximately estimating the rate of accumulation of NO₂ and N₂O based on Melia's data. According to these calculations, the extent of the disproportionation is generally negligible at low initial pressures, e.g. 5 atm or less, while at 200 atm, the mole fractions of NO₂ and N₂O can become as high as 12-13% only after 10 days. These values are alarmingly high for handling pressured NO- in N₂-mixture in either research or clinical settings. This information must be borne in mind when compressed NO in commercial cylinders is employed in high precision experiments. Disproportionation of NO under pressure also deserves attention in inhalation of low doses of NO in the treatment of diseases characterized by pulmonary hypertension and hypoxemia.     

(E)-2-(2-Hydroxyethylidene)-6-methyl-5-heptenal (alpha-acariolal) and (E)-2-(2-hydroxyethyl)-6-methyl-2,5-heptadienal (beta-acariolal), two new types of isomeric monoterpenes from Caloglyphus polyphyllae (Acari: Acaridae)

The opisthonotal gland secretion of the acarid mite, Caloglyphus polyphyllae, contained two new monoterpenes, (E)-2-(2-hydroxyethylidene)-6-methyl-5-heptenal (1) and (E)-2-(2-hydroxyethyl)-6-methyl-2,5-heptadienal (2), to which we have given the trivial names alpha- and beta-acariolal in relation to alpha- and beta-acaridial (3 and 4), respectively. Elucidation of the structure of 1 was established mainly from 1H-NMR and GC/MS spectral data after partial purification, together with the fact that 1 was recovered in the more-polar fraction from a silica gel column than alpha- and beta-acaridial (3 and 4) present in the secretion. Compound 2 was obtained in the same fraction as a mixture with 1. Based on the facts that 2 had the same molecular weight by GC/MS and the same polarity as that of 1, compound 2 was assumed to be a structural analog of 1. The structures of compounds 1 and 2 were confirmed by their synthesis in nine and ten respective steps starting from alpha-bromo-gamma-butyrolactone.     

Morphological and molecular variation in Mitchella undulata,with special reference to the systematic treatment of the dwarf form from Yakushima

Morphological and molecular variation in Mitchella undulata Siebold et Zucc. was examined to evaluate the genetic basis for recognizing the dwarf variety, M. undulata var. minor Masamune. Considerable variation in leaf size in M. undulata, but no obvious morphological discontinuities, were found between the normal and dwarf varieties. Instead, a weak cline running from the Pacific Ocean to the Sea of Japan was found. Anatomical observations of leaf blades revealed that the large variation in leaf size can be attributed to variation in the number of leaf cells and not to differences in cell size. A molecular analysis based on sequences of rDNA internal transcribed spacer regions indicated that there were two major genotypes in M. undulata with minor variation in haplotypes resulting from additional substitutions or putative recombination. The dwarf form from Yakushima was neither genetically uniform nor apparently differentiated from other populations. From these results, we conclude that the dwarf form of M. undulata should be treated at the rank of forma.     

Unequal cleavage in the early Tubifex embryo

Unequal cleavage that produces two blastomeres of different size is a cleavage pattern that many animals in a variety of phyla, particularly in Spiralia, adopt during early development. This cleavage pattern is apparently instrumental for asymmetric segregation of developmental potential, but it is also indispensable for normal embryogenesis in many animals. Mechanically, unequal cleavage is achieved by either simple unequal cytokinesis or by forming a polar lobe at the egg's vegetal pole. In the present paper, the mechanisms for unequal cytokinesis involved in the first three cleavages in the oligochaete annelid Tubifex are reviewed. The three unequal cleavages are all brought about by an asymmetrically organized mitotic apparatus (MA). The MA of the first cleavage is monastral in that an aster is present at one pole of a bipolar spindle but not at the other. This monastral form, which arises as a result of the involvement of a single centrosome in the MA assembly, is both necessary and sufficient for unequal first cleavage. The egg cortex during the first mitosis is devoid of the ability to remodel spindle poles. In contrast to the non-cortical mechanisms for the first cleavage, asymmetry in the MA organization at the second and third cleavages depends solely on specialized properties of the cell cortex, to which one spindle pole is physically connected. A cortical attachment site for the second cleavage spindle is generated de novo at the cleavage membrane resulting from the first cleavage; it is an actin-based, cell contact-dependent structure. The cortical microtubule attachment site for the third cleavage, which functions independently of contact with other cells, is not generated at the cleavage membrane resulting from the second cleavage, but is located at the animal pole; it may originate from the second polar body formation and become functional at the 4-cell stage.     

Induction of 72-kDa Inducible Heat Shock Protein (HSP72) in Cultured Rat Astrocytes After Energy Depletion

Abstract: Protein synthesis is important in the readaptive processes for cultured astrocytes after hypoxia and subsequent reoxygenation. We have identified 72-kDa inducible heat shock protein (HSP72) as a major stress protein in reoxygenated astrocytes. To assess the mechanism for reoxygenation-mediated induction of HSP72, a reporter gene that consists of a human HSP promoter fused to the luciferase gene was transfected into cultured astrocytes. Analysis of cellular energy nucleotides showed an increase of the ADP/ATP ratio after reoxygenation, which synchronized with activation of the HSP promoter. Activation of the HSP promoter was also observed after an addition of iodoacetic acid to hypoxic astrocytes, which reached the maximum when the ADP/ATP ratio reached 50%, but further decline in the energy profile caused inactivation of this promoter. Inhibition of protein synthesis after reoxygenation resulted in temporary restoration of the energy profile and suppression of the DNA binding activity of the heat shock factor. Addition of quercetin greatly decreased the [³H]leucine incorporation in the polysome fraction without any effect on the mature mRNA formation. These data suggest that the energy depletion in reoxygenation triggers induction of HSP72 after reoxygenation, which may act as a pivotal mediator in the stress response of reoxygenated astrocytes by facilitating protein synthesis.     

A Physical Map of Arabidopsis thaliana Chromosome 3 Represented by Two Contigs of CIC YAC, P1, TAC and BAC Clones

We have constructed a physical map of Arabidopsis thaliana chromosome3 by ordering the clones from CIC YAC, P1, TAC and BAC librariesusing the sequences of a variety of genetic and EST markersand terminal sequences of clones. The markers used were 112DNA markers, 145 YAC end sequences, and 156 end sequences ofP1, TAC and BAC clones. The entire genome of chromosome 3, exceptfor the centromeric and telomeric regions, was covered by twolarge contigs, 13.6 Mb and 9.2 Mb long. This physical map willfacilitate map-based cloning experiments as well as genome sequencingof chromosome 3. The map and end sequence information are availableon the KAOS (Kazusa Arabidopsis data Opening Site) web siteat http://www.kazusa.or.jp/arabi/.