bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Efficiency Plant Regeneration From Callus Induced on Mature Indica Rice Caryopses
Authors: Kunanuvatchaidach R , Godwin ID , Adkins SW
Published: December 2005

High frequency callus production was achieved following the culturing of mature caryopses on Murashige and Skoog (MS) medium containing MS vitamins, 10 then 5 μM 2,4-dichlorophenoxyacetic acid, 59 mM sucrose, 3 g L-1 casein hydrolysate and 8 g L-1 agar. Six south-east Asian Indica rice (Oryza sativa L.) cultivars produced embryogenic structures after 6 weeks of culture at 26 ± 1°C. Efficiency in embryogenic response of genotypes differed, Kurkaruppan = FR13A > Khao Dawk Mali 105 = Nam Sagui 19 = RD7 > Pin Gaew 56. Additives such as mannitol, tryptophan and ABA nor manipulation of light environment improved callus initiation or embryogenic callus formation. The use of a number of different plantlet regeneration media either free of plant growth regulators or containing auxins (indole-3-acetic acid and α-naphthaleneacetic acid), cytokinins (kinetin and 6-benzylaminopurine) and an ethylene producing chemical (1 -aminocyclopropane carboxylic acid) showed that the plant: growth regulator-free medium or the one supplemented with 1-aminocyclopropane carboxylic acid (5 μM) and kinetin mu 5 μM) were best for plantlet formation. However, a single recommendation could not be made for all cultivars. One further culture modification involving a mild osmotic stress (polyethylene glycol 100 g L-1) in R-2 liquid medium enhanced plantlet regeneration in Nam Sagui 19 two-fold but Khao Dawk Mali 105 was recalcitrant to this treatment. Plantlets (700) produced from all treatments subsequently developed into plants, most of which were morphologically normal, in the greenhouse.
Conservation of the Grassy White Box Woodlands: Relative Contributions of Size and Disturbance to Floristic Composition and Diversity of Remnants
Authors: Prober SM , Thiele KR
Published: December 2005

Before European settlement, grassy white box woodlands were the dominant vegetation in the east of the
wheat-sheep belt of south-eastern Australia. Tree clearing, cultivation and pasture improvement have led
to fragmentation of this once relatively continuous ecosystem, leaving a series of remnants which
themselves have been modified by livestock grazing. Little-modified remnants are extremely rare. We
examined and compared the effects of fragmentation and disturbance on the understorey flora of
woodland remnants, through a survey of remnants of varying size, grazing history and tree clearing. In
accordance with fragmentation theory, species richness generally increased with remnant size, and, for
little-grazed remnants, smaller remnants were more vulnerable to weed invasion. Similarly, tree
clearing and grazing encouraged weed invasion and reduced native species richness. Evidence for
increased total species richness at intermediate grazing levels, as predicted by the intermediate
disturbance hypothesis, was equivocal. Remnant quality was more severely affected by grazing than by
remnant size. All little-grazed remnants had lower exotic species abundance and similar or higher native
species richness than grazed remnants, despite their extremely small sizes (< 6 ha). Further, small, littlegrazed
remnants maintained the general character of the pre-European woodland understorey, while
grazing caused changes to the dominant species. Although generally small, the little-grazed remnants
are the best representatives of the pre-European woodland understorey, and should be central to any
conservation plan for the woodlands. Selected larger remnants are needed to complement these,
however, to increase the total area of woodland conserved, and, because most little-grazed remnants are
cleared, to represent the ecosystem in its original structural form. For the maintenance of native plant
diversity and composition in little-grazed remnants, it is critical that livestock grazing continues to be
excluded. For grazed remnants, maintenance of a site in its current state would allow continuation of
past management, while restoration to a pre-European condition would require management directed
towards weed removal, and could take advantage of the difference noted in the predominant life-cycle
of native (perennial) versus exotic (annual or biennial) species.
Key Periods in the Evolution of the Cenozoic Vegetation and Flora in Western Tasmania: the Late Pliocene
Authors: MacPhail MK , Colhoun EA , Fitzsimons SJ
Published: December 2005

Fossil pollen and spores in organic-rich sediments in a side gully in the Linda Valley, western Tasmania, preserve one of the most detailed records of a Late Pliocene flora and vegetation available to date in Australia. This includes Araucariaceae, Beauprea Brongn. & Gris. and a number of sub-canopy broadleaf trees now confined to warm temperate-tropical habitats. Changes in community dominance are interpreted in terms of alluvial events and point to the existence of altitudinally zoned plant communities in western Tasmania-Microstrobos J. Garden & L. Johnson heathland on the higher slopes and Nothofagus (Brassospora) Hill & Read-Lagarostrobos franklinii (J.D.Hook.) Quinn evergreen rainforest with or without Dacrydium Sol. ex Lamb. emmend. de Laub. at lower elevations. The evidence demonstrates the survival of Nothofagus (Brassospora) spp in western Tasmania at a time when other published data imply the taxon was virtually eliminated from the south-eastern mainland. It is proposed that increasingly seasonal climates drove an 'ecological wedge' into a former continuum of wet forest types along the east coast of Australia, with Plio-Pleistocene glaciation being ultimately responsible for the demise, of what had become relict populations, of Brassospora spp. in western Tasmania.
Functional Anatomy of the Oil Glands of Melaleuca alternifolia (Myrtaceae)
Authors: List S , Brown PH , Walsh KB
Published: December 2005

The structure and development of the oil glands of Melaleuca alternifolia (Maiden & Betche) Cheel is described with reference to the production of essential oil. Oil glands were first apparent in immature leaves (ca. node 3) and continued to form, while density per unit area decreased, as the leaf expanded. The number of glands in a leaf reached a maximum prior to full leaf expansion. A genetic component related to oil gland density was indicated by a lower variation in the number of glands in the most recently fully expanded leaf within a plant than between plants of the same seed source. Oil yield was not, however, correlated with oil gland density. The cavity of the gland formed schizogenously or schizo-lysigenous. No significant variation was recorded in Be yield and composition of the oil over a 48 h period. Short term (8 day) water stress did not effect oil yield or composition. These observations are consistent with the concept of a one-way developmental pathway for oil gland formation and oil content. Varying nitrogen and phosphorus nutrition and light levels over a 3 month period did not influence oil gland density or specific oil yield from leaves formed under the imposed conditions. The effect of plant nutrition on oil production must therefore be explained by the effect on biomass production. The glands were capped by modified epidermal cells. Oil was observed to pass through these cells when the leaf was subjected to vacuum, and may allow a gradual loss of oil from the glands under field conditions.
Fruit Development of Pistacia vera (Anacardiaceae) in Relation to Embryo Abortion and Abnormalities at Maturity
Authors: Shuraki YD , Sedgley M
Published: December 2005

This study investigated fruit development of the Pistacia vera L. cultivars Kerman and Sirora using bright field microscopy. Normal fruit development was compared with that of seedless (blank) and small seeded (semi-blank) fruits to identify the stages at which degeneration occurred. In normal fruits, pericarp growth took place up to week 4 after pollination and preceded embryo, endosperm and funicle proliferation between weeks 4 and 16. Endocarp (shell) and exocarp (hull) development occurred between weeks 8 and 16. Blank and semi-blank fruits were identified by slower growth and lack of exocarp colouration. Blank fruits resulted from one of five patterns of ovule degeneration caused by funicle degeneration, embryo sac absence, embryo sac degeneration, lack of pollen tube penetration of the embryo sac, or failure of endosperm cellularisation. Funicle degeneration was the most common cause of blanking and was observed either at the site of pollen tube penetration or at the chalazal end of both pollinated and unpollinated ovules. Degeneration of funicular tissue extended towards the vascular bundles. Small seeded or semi-blank fruit resulted from degeneration of the cotyledons during the latter stage of embryo development.
Heritable Chilling Tolerance Improvement in Rice Through Somaclonal Variation and Cell Line Selection
Authors: Bertin P , Kinet JM , Bouharmont J
Published: December 2005

Embryo-derived calli of four rice varieties (Oryza sativa L.) were submitted to different continuous or discontinuous periods of chilling stress at 4°C, with a total length varying from 2 to 6 weeks. Other calli were cultivated during different times without cold stress. The reduction of plant regeneration percentages induced by low temperature was more pronounced in the more cold-sensitive varieties. Regenerated plants (R0) and their descendants in R1, R2 and R3 generations were cold-screened together with control plants. A mass selection was applied to the control plants during three successive generations. In all varieties, significantly higher chilling survival rates were obtained in R3 with in vitro grown plants than with control plants. Higher plant survival rates were obtained with the more chilling-sensitive varieties when a short discontinuous chilling treatment or no treatment had been applied, with the intermediate variety with short or intermediate treatments, and with the more cold-tolerant variety with longer, continuous treatments. The relative importance of pre-existing versus in vitro-induced variation and of epigenetic versus heritable variation, along with the significance of such cold tolerance improvement for breeding purposes are discussed.
Factors Limiting the Recruitment of Eucalyptus salmonophloia in Remnant Woodlands. III. Conditions Necessary for Seed Germination
Authors: Yates CJ , Hobbs RJ , Bell RW
Published: December 2005

Characteristics of the germination strategy of Eucalyptus salmonophloia are described, and whether the germination niche is limiting recruitment of E. salmonophloia seedlings in remnant woodlands is discussed. Germination in E. salmonophloia proceeds with favourable soil temperature and water conditions on a variety of substrates. However, at temperatures above and below the optimum for germination (25°C), enforced dormancy occurs and germination is retarded. In these situations, dormancy is simply overcome when temperatures return to optimum. Seeds can remain moist at sub-optimum temperatures for prolonged periods without losing viability. Furthermore E. salmonophloia seeds are capable of withstanding a cycle of wetting and drying with undiminished germination capacity. Conditions suitable for germination occur at the beginning of the winter wet season in SW Australia when soil temperatures are still suitable and soil moisture and atmospheric humidity are frequently high. These germination characteristics minimize the chances of seeds germinating at times when the probability of seedling establishment is low (e.g. summer). This is particularly important because E. salmonophloia only establishes a temporary soil, seed-reserve following large scale disturbances, and therefore the opportunities for recruitment may be quite rare. In remnant woodland when ants were excluded and a soil seed-bank was created artificially, seeds germinated, but no seedlings survived. This suggests that the destruction of seeds by ants during inter-disturbance periods is having little effect on recruitment because seedlings are unlikely to establish. Unfavourable conditions for germination are unlikely to be responsible for the lack of E. salmonophloia seedling recruitment in remnant woodlands.Further research is needed to identify the factors critical for
seedling establishment; changes in resource availability following large-scale disturbances and
associated tree death are important in this respect.
Regeneration in a Pole-Stage Forest of Eucalyptus regnans Subjected to Different Fire Intensities in 1982
Authors: Ashton DH , Martin DG
Published: December 2005

In 1982, fire burnt stands of Eucalyptus regnans F.Muell. in a relatively dry site in Victoria. In one area,
the fire killed both canopy and understorey; in an adjacent area, only understorey was destroyed.
Regeneration in the two areas was similar over the following year, but diverged thereafter to produce
understoreys with different species dominance. In both stands, a poor supply of mature E. regnans seed
in the crowns at the time of the fire resulted in relatively low initial density of seedlings: in the firekilled
stand, this meant that closure of the canopy of the stratum was delayed for 5 or 6 years; however,
in the understorey-killed stand, none of the E. regnans seedlings survived for 2 years. The soil seed
bank was reduced more severely in the fire-killed than in the understorey-killed stand, although not all
seed germinated in the first year. Vegetative regeneration of herbs and shrubs occurred from shallower
layers of soil in the understorey-killed than in the fire-killed stand. An increase in soil fertility after the
fire, as measured by seedling bioassay, was apparent only in the first season after the fire and was
correlated with higher levels of available P. In the understorey-killed stand, fertility in the topsoil was
greater than that in the fire-killed stand, and growth in diameter at breast height of dominant trees was
significantly greater than in adjacent unburnt stands in the first few years after the fire. By comparison,
when fire burnt through a site of higher rainfall after the maturation of the current crop of canopy-stored
seed, regeneration was initially denser and growth considerably greater than that in the drier site. The
study demonstrated that the course of secondary succession depends on site quality, timing of the fire in
relation to seed production, soil seed germination, vegetative growth from protected organs, the severity
of the fire, the presence or absence of browsing, and, in the long term, the frequency of recurrent fire.
Susceptibility of Plant Species in Banksia Woodlands on the Swan Coastal Plain, Western Australia, to Infection by Phytophthora cinnamomi
Authors: Shearer BL , Dillon M
Published: December 2005

Estimates of the susceptibility of plant species in Banksia woodland to Phytophthora cinnamomi Rands were obtained by determining the incidence of plant death and frequency of isolation of the pathogen, among species occurring in 46 disease centres on the Swan Coastal Plain south of Perth, Western Australia. In the disease centres, dicotyledons outnumbered monocotyledons. About half of all species occurring in the disease centres were from four families of dicotyledons, with the largest number of species from the Myrtaceae, Proteaceae and Papilionaceae. The greatest number of species of monocotyledons were from the Anthericaceae and Cyperaceae. No deaths were recorded for 47% of species found in three or more disease centres. These species were mainly from the Cyperaceae, Haemodoraceae, Myrtaceae and Papilionaceae. The species that tended to die frequently in disease centres were mainly from the Papilionaceae, Proteaceae, Epacridaceae, Xanthorrhoeaceae and the Zamiaceae. Phytophthora cinnamomi was isolated from 26 of the 95 species occurring in three or more disease centres. For most species, the frequency of isolation of P. cinnamomi from recently dead plants was much less than the frequency of dead plants sampled. Isolation from plants was less frequent than from adjacent soil. The pathogen was isolated from recently dead plants or soil mainly for species of the Proteaceae, Myrtaceae, Papilionaceae, Dasypogonaceae, Iridaceae and Xanthorrhoeaceae. Cross-tabulation of species by incidence of plant death and isolation of P. cinnamomi from plant and soil, provided the opportunity to classify the response of plant species to infection by P. cinnamomi.
Reflection of Near-Ultraviolet Radiation From Flowers of Australian Native Plants
Authors: Dyer AG
Published: December 2005

Eighty-six species of Australian native plants were assessed in the near-ultraviolet (UV-A) (320-400 nm) and visible regions of the electromagnetic spectrum. Relationships between flower colour, size, symmetry and UV-A reflection were examined. The frequency of species in this sample that reflected UV-A radiation was found to be consistent with major overseas studies. A quantitative photographic study of the spectral reflection from the yellow flower of Hibbertia obtusifolia DC. (Dilleniaceae) was conducted for radiation with wavelengths of 280-800 nm. How an insect with UV-A-, blue- and green-sensitive photoreceptors might see H. obtusifolia as a two-coloured flower, and how this could aid a floral visitor's orientation is discussed.
Ecogeographical Analysis of Hakea (Proteaceae) in South-Western Australia, With Special Reference to Leaf Morphology and Life Form
Authors: Groom PK , Lamont BB
Published: December 2005

The genus Hakea Schrader (Proteaceae) has its world centre of diversity in south-western Australia; the majority (c. 70%) of species are endemic to this region. To examine the distribution of Hakea within south-western Australia, canonical correspondence analysis (CCA) was used on species presence and bioclimatic parameters in 0.5° x0.5° latitude-longitude grid cells. Of the 12 bioclimatic attributes initially applied, annual temperature and rainfall data, and indices of their variation, were best related to species distribution. Clustering of the species (on the CCA ordination) produced five distinct groups (not including species near the origin of the ordination) roughly representing floristic regions of southwestern Australia (Avon, Irwin, Eyre-Roe, southern Darling, northern-central Darling). Species distribution was then related to four morphological groups based on their leaf type (broad, terete) and post-fire life form (non-sprouter, resprouter). The highest percentage of terete-leaved non-sprouters occurred in areas of low-moderate rainfall and large annual temperature ranges (Avon and Eyre-Roe clusters), whereas terete-leaved resprouters displayed a very patchy distribution, accounting for less than 20% of the hakeas present in most of the grid cells. Broad-leaved resprouters dominated areas of strongly seasonal rainfall (Irwin and northern-central Darling clusters), with few species occurring in the drier Avon and Eyre-Roe districts. Broad-leaved non-sprouters were best represented in areas of low annual temperature (southern Darling and Eyre-Roe clusters). The distribution of non-sprouters and resprouters may be due to climatic factors affecting seedling recruitment and/or fire frequencies. Leaf morphology appears to be more directly related to species distribution, as broad leaves are favoured in regions of medium-high, seasonal rainfall (less stressful habitats) while terete leaves are better adapted to tolerate hot, dry environments.
Distribution and Floristics of Terricolous Lichens in Soil Crusts in Arid and Semi-Arid New South Wales, Australia
Authors: Eldridge DJ
Published: December 2005

This paper examines the distribution of terricolous lichens at a regional scale across seven landscape types over 60 000 km2 in western New South Wales. Data are also presented on the distribution of lichens within a geomorphic sequence of runoff and runon zones on a red earth soil near Cobar. On a regional scale, 48 taxa from 23 genera were collected from 282 sites in semi-arid and arid eastern Australia, Of these, 74% were crustose or squamulose, and the remainder (26%) were foliose. Six genera (Acarospora, Endocarpon, Catapyrenium, Diploschistes, Peltula and Xanthoparmelia) accounted for 57% of species. Landscape type was a poor predictor of lichen floristics or crust cover. Instead, a core group of species comprising Collema coccophorum, Heppia despreauxii, Endocarpon rogersii, E. simplicatum var. bisporum, E. pallidum, Psora decipiens, Peltula patellata ssp. australiensis, Catapyrenium squamulosum and Synalissa symphorea, occurred in all landscape types. Plains with red earths had the greatest mean number of species per site (11.2) and the greatest mean crust cover (27.7%). Plains of calcareous earths yielded the greatest number of species (38). Across all sites, crust cover was a poor predictor of lichen species richness. However, on landscape types with non-calcareous soils, mean crust cover explained 88% of the variation in mean number of species. Whilst there was no difference in total number of species across a sequence of geomorphic zones, crust cover was significantly greater in the interception zones (79.0%) compared with either the run-on (6.6%) or run-off (24.0%) zones. These distributional data are compared with other published and unpublished studies from similar areas in Australia. The role of terricolous crusts as indicators of ecosystem health, and the influence of land management on crust cover and subsequent landscape stability are discussed.
DNA Binding Compounds. VII. Synthesis, Characterization and DNA Binding Capacity of 1,2-Dicarba-closo-dodecaborane Bibenzimidazoles Related to the DNA Minor Groove Binder Hoechst 33258
Authors: Bateman Stuart A. , Kelly David P. , White Jonathan M. , Martin Roger F.
Published: December 2005

A series of bibenzimidazole derivatives based on the known DNA minor groove
binder Hoechst 33258 have been prepared to include a
1,2-dicarba-closo-dodecaborane cage for potential use in
boron neutron capture therapy (BNCT). The carborane derivatives (5){(7)
were chosen to reduce the steric inhibition of minor groove DNA binding
displayed by the previously prepared carborane ligand (4). The synthesis and
preliminary DNA binding studies of these bibenzimidazole derivatives are
presented herein.
Iron(II) and Nickel(II) Complexes of 6-(Pyrazol-1-yl)-2,2' -bipyridine
Authors: Baker Anthony T. , Matthews Jeremy P.
Published: December 2005

Iron(II) and nickel(II) complexes of 6-(pyrazol-1-yl)-2,2′-bipyridine
(pzbpy) have been prepared and characterized by magnetic susceptibility
measurements and electronic spectroscopy. The magnetic behaviour of the
iron(II) complexes and the electronic spectra of the nickel(II) complex
indicate that pzbpy is a relatively strong-field ligand though its field
strength is not as high as that of 2,2′:6′,2″-terpyridine.
Comparisons of the field strength of terimine and analogous ligands are
presented.
Structural studies of some 1-polymethyleneimino-2,4-dinitrobenzenesand related compounds; crystal structure of 1-(cis-2′,6′-dimethylpiperidin-1′-yl)-2,4-dinitrobenzene
Authors: Mackay Maureen F. , Gale Douglas J. , Wilshire John F. K.
Published: December 2005

The ultraviolet and 1H n.m.r. spectra of some
1-polymethyleneimino-2,4-dinitrobenzenes and related compounds are discussed.
The effect of trifluoroacetic acid on these spectra was also investigated;
with 1-azetidinyl-2,4-dinitrobenzene, acid-catalysed ring opening was
observed. The solid-state conformation of
1-(cis-2′,6′-dimethylpiperidin-1′-yl)-2,4-dinitrobenzene
has been defined by single-crystal X-ray crystallography. Triclinic crystals
belong to the space group P–1 with
a 8.165(1), b 7.865(1),
c 11.148(1) Å, α 95.23(1), β 106.00(1),
γ 92.63(1)˚ and Z 2. The structure was refined
to a final R of 0.048 for the 2222 observed data. In the
crystal, the phenyl ring adopts a slight boat conformation, while the amino
and o-nitro groups are significantly twisted from the
mean plane of the ring.
Exploration of the Paternò - Büchi Reaction as a Potential Route to the Oxetan Ring of Taxol®
Authors: Gan Chee Yong , Lambert John N. , Gable Robert W.
Published: December 2005

Two photochemical pathways to paclitaxel-like oxetan rings have been examined.
In the first approach, an intramolecular Paternò–BÜchi
reaction on a 6,7-enal was attempted without success. The intermolecular
variation using a bicyclic alkene in the presence of either benzaldehyde or
acetophenone delivered oxetans whose regiochemistry was the same as that found
in paclitaxel but opposite in stereochemistry. The crystal structures of a key
intermediate diol and a photochemically generated oxetan are
reported.
Crystal and Molecular Structures of Ru3(µ-dppm)(CO)9 {PPh2(C6H4N=CHPh-2)}
Authors: Bruce Michael I. , Kühl Olaf , Skelton Brian W. , White Allan H.
Published: December 2005

The crystal and molecular structures of
Ru3(µ-dppm)(CO)9
{PPh2(C6H4N=CHPh-2)}
are reported.
β-Acarbose. VII. Approaches Towards the Synthesis of Some N-Linked Carba-Oligosaccharides
Authors: Tilbrook Matthew G. , Stick Robert V. , Williams Spencer J.
Published: December 2005

3,4-Anhydro-1,6-dideoxy-1,6-episeleno-β-D-glucose was treated with
cyclohexylamine to afford an amino diol which was subsequently converted into
a cyclic carbamate, a compound shown to be a moderately successful glycosyl
donor. Treatment of the same 3,4-anhydro sugar and the 1,6-epithio analogue
with a 1-epivalienamine derivative afforded the corresponding secondary amines
which were converted into the analogous cyclic carbamates. The epithio
analogue was unsuccessful as a glycosyl donor, failing to glycosylate a
carbohydrate alcohol. On the other hand, the episeleno compound appeared to
function as a glycosyl donor but decomposition of the product occurred under
the conditions necessary for its isolation.
Dihydro-1,2,4-triazin-6(1H)-ones. III. Oxidation Products of 1-Methyl-3-phenyl- 4,5-dihydro-1,2,4-triazin-6(1H)-one
Authors: Collins David J. , Hughes Timothy C. , Johnson Wynona M.
Published: December 2005

1-Methyl-3-phenyl-4,5-dihydro-1,2,4-triazin-6(1H)-one
(1) undergoes aerial oxidation to give a mixture of 1-
methyl-3-phenyl-1,2,4-triazin-6(1H)-one (2) and
1-methyl-3-phenyl-1,4-dihydro-1,2,4-triazine-5,6-dione (3). The dehydro
derivative (2) was cleanly prepared by the oxidation of (1) with
2,3-dichloro-5,6-dicyano-1,4- benzoquinone (ddq). The dehydro derivative (2)
underwent a surprising rearrangement to the triazole (12) upon oxidation with
OxoneR. Several attempts at unambiguous synthesis of the
α-dicarbonyl derivative (3) were unsuccessful; it was obtained, together
with the 1,4-dimethyl derivative (13) by methylation of 3-phenyl-1,4-
dihydro-1,2,4-triazine-5,6-dione (4) with sodium hydride and methyl iodide.
Synthesis and Structure of the Dinuclear Tungsten(V) Complex {HB(Me2C3N2H)3}WS(µ-S)2WS(S2PPh2)
Authors: Eagle Aston A. , Gable Robert W. , Young Charles G.
Published: December 2005

The complex LW V S(µ-S) 2 W
V S(S 2 PPh
2 ) [L =
tris(3,5-dimethylpyrazol-1-yl)hydroborate] results from the reaction of
LW VI O 2 Cl with PPh 3 in
refluxing pyridine, followed by the addition of NH 4 S
2 PPh 2 and reflux for a further 4
days. Crystals of LWS(µ-S) 2 WS(S
2 PPh 2 )·0.5CH
2 Cl 2 are monoclinic and belong
to space group Cc with a
12.356(2), b 30.067(6), c
22.082(4) Å, β 96.08(2)° and
Z 8. Refinement of 10507 data measured with Mo Kα
radiation converged at R 0.0466 and
R w 0.1421. The two independent
molecules in the unit cell are dinuclear with a
syn-[W 2 S
2 (µ-S) 2 ]
2+ core. One tungsten centre is further coordinated
by a tridentate L ligand, making it six-coordinate with a distorted octahedral
geometry while the other bears a bidentate dithiophosphinate ligand and is
five-coordinate and square- pyramidal in geometry. The terminal
thio–tungsten distances average 2.120 Å, and the parameters of the
core [W–W av. 2.832 Å, W–(µ-S) av. 2.311 Å,
S–W–S av. 100.2°, W–S–W av. 75.2°] are
typical of syn-[W 2 S
2 (µ-S) 2 ]
2+ complexes.
The Structure of Chalybaeizanic Acid and Quaesitic Acid, Two New Lichen Depsidones Related to Salazinic Acid
Authors: Elix John A. , Wardlaw Judith H.
Published: December 2005

The depsidones chalybaeizanic acid
(1,4,10-trihydroxy-8-methyl-3,7-dioxo-1,3-dihydro-7
H-isobenzofuro-
[4,5-b][1,4]benzodioxepin-5,11-dicarbaldehyde)
(4) and quaesitic acid (11-formyl-1,4,10-trihydroxy-8-
methyl-3,7-dioxo-1,3-dihydro-7
H-isobenzofuro[4,5-b][1,4]benzodioxepin-5-methyl
hydrogen fumarate) (5) have been isolated from the lichens
Xanthoparmelia amphixanthoides and
Hypotrachyna quaesita respectively, and their structures
determined by a combination of spectroscopic evidence, partial synthesis,
derivatization or degradation reactions.
Synthesis of Homophthalates from Allenic Diesters: Conversion into Viocristin and Analogues, and Application to 6-Methylpretetramid.
Authors: Cameron Donald W. , Caliskan Ece , Griffiths Peter G.
Published: December 2005

Oxy-substituted homophthalic anhydrides have been synthesized by cycloaddition
of di- and tri-oxy butadienes to the allenic diester (1). By base-catalysed
cycloaddition to appropriate benzoquinones they have afforded new syntheses of
viocristin (19), isoviocristin (20) and analogous 1,4-anthraquinones. Related
chemistry has led to the naphthalene (34) and the anhydride (35),
intermediates in published syntheses of semivioxanthin and 6-
methylpretetramid respectively.
Pigments of Fungi. LVI.
Dermocanarin 7, a New Naphthalene - Dihydroanthracenone - Oxanthrone Trimer from an Australian Dermocybe Toadstool
Authors: Buchanan Malcolm S. , Gill Melvyn , Yu Jin , Phonh-Axa Somphone
Published: December 2005

Dermocanarin 7 (3), a unique combination of a macrocyclic lactone of the
dermocanarin class with an oxanthrone, is isolated from an indigenous
Australian toadstool belonging to the genus Dermocybe.
The structure of dermocanarin 7 (3) is determined mainly from spectroscopic
data, while the absolute stereochemistry at the three chiral centres and at
the chiral axis follows from the c.d. spectrum of (3) and the results of NOESY
and other n.m.r. experiments.
New Aryl Edge - Edge Packing Interactions Involving the N-Oxide Functional Group.
Authors: Nguyen Vi T. , Scudder Marcia L. , Rahman A. Noman M. M. , Bishop Roger , Craig Donald C.
Published: December 2005

The X-ray crystal structures of
5b,6,12b,13-tetrahydropentaleno[1,2-b:4,5-b´]diquinoline
5,12-dioxide (5) and
(6α,7α,14α,15α)-7,15-dibromo-6,7,14,15-tetrahydro-6,14-methanocycloocta[1,2-b:5,6-b´]diquinoline
5,13- dioxide (6) reveal two new packing modes of potential importance as
supramolecular synthons for molecular assembly. Both involve intermolecular
edge–edge association of an aryl ring and an
N-oxide functionality. One is a bifurcated
Ar–H···O(N)···H–Ar
interaction which on repetition gives infinite chains of the molecules. The
second is a 10-membered centrosymmetric dimer also involving
Ar–H···O–N interactions but which merely
links two neighbouring molecules of (6). The latter arrangement is a
structural analogue of a recently reported dimeric centrosymmetric
eight-membered Ar–H···N synthon.
Exploratory Studies on the Synthesis of the Unusual Diterpenoid Tropone Harringtonolide.
Authors: Rogers Daniel H. , Frey Barbara , Roden Francis S. , Russkamp Friedrich-Wilhelm , Willis Anthony C. , Mander Lewis N.
Published: December 2005

Various approaches to the total synthesis of the unusual diterpenoid tropone
(2), discovered in the yew species
Cephalotaxus harringtonia and
C. hainanensis, are described. The rhodium-catalysed
intramolecular cyclopropanation reaction of an aryl ring by means of the
transition metal catalysed reaction of a diazoacetyl function was used to
assemble the 5/7 ring system and to provide a cycloheptatrienyl precursor
to the tropone moiety, e.g.(28)→(29) and (38) →(39). In the most
promising approach, the carbocyclic system was assembled by means of the aldol
reaction (42) →(43) with the newly formed α-hydroxyl being employed
subsequently in the formation of the δ-lactone function of (44). The
tropone ring may be formed from the methoxycycloheptatriene moiety simply by
treatment with mercuric nitrate. Tropone (45) was formed from (44) in this
way, but attempts to convert it into harringtonolide by means of transannular
oxidation based on the 4-hypoiodite failed. The crystal structure of an
intermediate is reported.
Deprotonation and Alkylation of 2-Methyl-4,5,6,7-tetrahydro-3H-azepine
Authors: Brimble Margaret A. , Gorsuch Stephen
Published: December 2005

The deprotonation of
2-methyl-4,5,6,7-tetrahydro-3H-azepine (5) using lithium
diisopropylamide was effected at −30°C in tetrahydrofuran. Addition
of deuterium oxide resulted in >95% incorporation of deuterium at
the exocyclic position. Addition of a range of electrophiles to the
organolithium species afforded moderate yields of the alkylation products
wherein substitution at the exocyclic position had occurred.
New Macrocyclic Ligands. IX. N-Benzylated Macrocycles Incorporating O2N2-, O3N2- and O2N3-Donor Sets.
Authors: Kim Jeong , Lee Youngran , Lindoy Leonard F. , Lee Shim Sung , Strixner Tania
Published: December 2005

The syntheses of N-benzylated macrocyclic ligands
incorporating O2N2-,
O3N2- and
O2N3-donor sets, and ring sizes
from 15- to 18-membered, is described. The new derivatives were obtained by
benzylation of the previously reported parent macrocycles with benzyl bromide
in acetonitrile containing suspended sodium carbonate or bicarbonate. The
X-ray structure determination of a tribenzylated product containing a
17-membered, O2N3-donor
macrocyclic ring is described.
John T. Pinhey
Authors: Ridley Damon
Published: December 2005

… international status through a ‘named reaction’ …
From IUPAC. Guidelines for publication of research from force-field calculations
Authors: Raber Douglas J , White Allan H
Published: December 2005

A synthesis of N-acetyl-4-deoxyneuraminic acid (11) from
N-acetylneuraminic acid (1) via the corresponding
unsaturated derivative (4) is described. This synthesis of the important
N-acetylneuraminic acid aldolase (EC 4.1.3.3) inhibitor
overcomes several difficulties associated with two previously published
syntheses.
Effects of granular nematicides on Valencia orange trees infested with Tylenchulus semipenetrans
Authors: Harris AR
Published: December 2005

Three granular nematicides were applied at six-seven week intervals to soil around Valencia orange trees infested with the citrus nematode, Tylenchulus semipenetrans. Fenamiphos [two and three applications of 10 kg active ingredient (a.i.)/ha] and aldicarb (three applications of 8 kg a.i./ha) temporarily reduced populations of T. semipenetrans in roots, but fruit yields did not increase in the two subsequent harvests. 1,2-dibromo-3-chloropropane (D.B.C.P.) (two applications of 40 kg a.i./ha) had no effect on either nematode populations or yield. The nematicides did not affect the percentage of California red scale parasitized by biological control agents. Aldicarb residues were found in orange pulp, juice and rind eight months after application, but low residues of D.B.C.P. were found only in rind, and no fenamiphos residues were detected.
Variation in nutritive value of plant parts of subterranean clover (Trifolium subterraneum L.)
Authors: Ru Y. J. , Fortune J. A.
Published: December 2005

While it has been reported that leaves of
subterranean clover are less digestible than stems, there is a lack of
information on the variability of nutritive value of plant parts of
subterranean clover. To determine the variation in nutritive value of leaf,
petiole, stem and burr, an experiment with 26 cultivars of subterranean clover
was conducted at Shenton Park Field Station, Perth, Western Australia. The
cultivars were divided into 3 maturity groups according to flowering time and
each cultivar was sown in blocks comprising 4 replicates. The plots were
grazed by sheep at 2-weekly intervals. Plants were sampled at the vegetative
stage before grazing and after the cessation of flowering. Dry matter
digestibility (DMD) and nitrogen concentration of leaves, petioles, stems and
burrs were determined. At the vegetative stage, there was no difference in DMD
(P>0.05) among plant parts for most cultivars, and
leaf had the highest (P<0.05) nitrogen concentration
(4.8–5.4%). After the cessation of flowering, leaf had the
highest DMD and nitrogen concentration (P<0.05). The
DMD of plant parts differed significantly among cultivars
(P<0.05). There was a slight decrease in DMD over
time for leaves and a significant decrease in DMD for stems and petioles.
These results suggest the main objective of grazing management of subterranean
clover swards should be to increase the proportion of leaf material in the
swards and that selection of leafy varieties by breeding could improve the
late season digestibility of subterranean clover. Such management and breeding
strategies would have value when the cultivars are in mixed pastures or used
with supplements in summer.
Development of a hemp (Cannabis sativa L.) simulation model 1.General introduction and the effect of temperature on the pre-emergent development of hemp
Authors: Lisson S. N. , Mendham N. J. , Carberry P. S.
Published: December 2005

In recent times, there has been a revival of
interest in hemp (Cannabis sativa L.), principally as a
source of fibre in paper and pulp manufacture. Studies assessing the
production potential and optimum crop management of hemp could benefit from
the use of a simulation model that captures crop growth and development
processes in response to management, genotypic, soil and climate factors. Such
a model would complement the more traditional agronomic field trial programs
by helping to identify the need, extent and nature of such trials, and by
extrapolating limited field results across both temporal and spatial
dimensions.
The hemp model described in the final paper in this series, divides crop
phenology into 5 phases, the first of which includes the pre-emergent
processes of germination and the subsequent elongation of hypocotyl and
radicle. This first paper reports on a study into the response of these
pre-emergent processes to temperature. The primary objectives were to
establish a simple model for predicting the duration from sowing to emergence
and to obtain estimates for the cardinal temperatures of hemp growth and
development. Cardinal temperatures are required for the estimation of thermal
time, which drives phenological development and canopy expansion in the hemp
model.
The germination response of the hemp cultivar Kompolti was measured at 13
different temperatures in incubators set between 1 and 55˚C. Similarly,
the response of radicle and hypocotyl elongation to temperature was measured
at 8 different temperatures in incubators set between 10 and 40˚C.
Development rates for each phase of pre-emergent development were then
calculated from time response plots of germinant number, hypocotyl and radicle
length. Finally, piecewise linear models were fitted to plots of development
rate versus temperature in order to calculate thermal time durations for each
phase and cardinal temperatures for hemp growth and development. Estimates of
the optimum and maximum temperatures from the elongation study were relatively
consistent, with average values of 28.6 and 40.7˚C, respectively. Base
temperature estimates were less consistent, ranging from 1.4˚C for the
hypocotyl linear phase, to 6.2˚C for the radicle lag phase. This
variability made it difficult to identify a common base temperature for use in
the hemp model. However, there was some evidence to support previously
reported base temperature estimates ranging from 0 to 2.5˚C. Assuming a
common base temperature of 1˚C, the average thermal time requirements for
germination and the lag and linear phases of hypocotyl elongation were
24.1˚Cd, 44.5˚Cd and 1.34˚Cd/mm, respectively.
A taxonomic revision and morphological variation within Eucalyptus series Subulatae subseries Oleaginae (Myrtaceae), including the oil mallee complex, of south-western Australia
Authors: Nicolle D. , Byrne M. , Whalen M.
Published: December 2005

Morphological variation within Eucalyptus series Subulatae subseries Oleaginae, a group of mallee taxa distributed in south-western Australia, was assessed by adult and seedling characteristics. A total of 36 adult morphological characters and 20 seedling characters was included in phenetic analyses of 82 individuals representing 29 populations covering all the taxa and the broad geographical distribution of the series. The phenetic analyses indicate relatively weak separation of all previously recognised taxa within E. subser. Oleaginae, except for E. longissima (previously referred to as E. grasbyi), which is distinctive in its seedling morphology, and to a lesser degree, E. ultima, which is also most easily distinguished by seedling morphology. E. eremicola, E. peeneri and E. sublucida are not well differentiated from one another, differing significantly only in adult leaf colour and gloss. The three previously recognised species of the oil mallee complex (E. kochii, E. plenissima and E. ‘horistes’) are also only weakly differentiated from one another. Two variants within E. kochii were observed to differ from each other in several adult vegetative and floral characteristics and are recognised at the subspecific level. A new taxonomy for E. subser. Oleaginae is presented, based on phenetic analyses combined with extensive field, glasshouse and herbarium examination of all taxa in the subseries. A new species is described (E. longissima Nicolle sp. nov.) to accommodate populations of mallees previously erroneously referred to E. grasbyi. New combinations are made for E. peeneri [E. eremicola subsp. peeneri (Blakely) Nicolle comb. nov.] and E. oleosa var. borealis [E. kochii subsp. borealis (C. Gardner) Nicolle comb. nov.] and two new subspecies of E. kochii are described (subspp. amaryssia Nicolle and yellowdinensis Nicolle). Eucalyptus sublucida is considered to be synonymous with E. eremicola subsp. peeneri. Keys to the taxa within the subseries are presented.
Intraprotein transfer of the quinone analogue inhibitor 2,5-dibromo-3-methyl-6-isopropyl-
p
-benzoquinone in the cytochrome b
6
f
complex
Authors: Yan Jiusheng , Kurisu Genji , Cramer William A.
Published: December 2005

Details are presented of the structural analysis of the cytochrome
b
6
f
complex from the thermophilic cyanobacterium,
Mastigocladus laminosus
, in the presence of the electrochemically positive (
p
)-side quinone analogue inhibitor, 2,5-dibromo-3-methyl-6-isopropylbenzoquinone (DBMIB). One DBMIB binding site was found. This site is peripheral to the quinone binding space defined by the binding sites of other
p
-side inhibitors previously resolved in cytochrome
bc
1
/
b
6
f
complexes. This high-affinity site resides in a
p
-side interfacial niche bounded by cytochrome
f
, subunit IV, and cytochrome
b
6
, is close (8 Å) to the
p
-side heme
b
, but distant (19 Å) from the [2Fe-2S] cluster. No significant electron density associated with the DBMIB was found elsewhere in the structure. However, the site at which DBMIB can inhibit light-induced redox turnover is within a few Å of the [2Fe-2S] cluster, as shown by the absence of inhibition in mutants of
Synechococcus
sp. PCC 7002 at iron sulfur protein-Leu-111 near the cluster. The ability of a minimum amount of initially oxidized DBMIB to inhibit turnover of WT complex after a second light flash implies that there is a light-activated movement of DBMIB from the distal peripheral site to an inhibitory site proximal to the [2Fe-2S] cluster. Together with the necessary passage of quinone/quinol through the small Q
p
portal in the complex, it is seen that transmembrane traffic of quinone-like molecules through the core of cytochrome
bc
complexes can be labyrinthine.
Determination of an ensemble of structures representing the intermediate state of the bacterial immunity protein Im7
Authors: Gsponer Joerg , Hopearuoho Harri , Whittaker Sara B.-M. , Spence Graham R. , Moore Geoffrey R. , Paci Emanuele , Radford Sheena E. , Vendruscolo Michele
Published: December 2005

We present a detailed structural characterization of the intermediate state populated during the folding and unfolding of the bacterial immunity protein Im7. We achieve this result by incorporating a variety of experimental data available for this species in molecular dynamics simulations. First, we define the structure of the exchange-competent intermediate state of Im7 by using equilibrium hydrogen-exchange protection factors. Second, we use this ensemble to predict Φ-values and compare the results with the experimentally determined Φ-values of the kinetic refolding intermediate. Third, we predict chemical-shift measurements and compare them with the measured chemical shifts of a mutational variant of Im7 for which the kinetic folding intermediate is the most stable state populated at equilibrium. Remarkably, we found that the properties of the latter two species are predicted with high accuracy from the exchange-competent intermediate that we determined, suggesting that these three states are characterized by a similar architecture in which helices I, II, and IV are aligned in a native-like, but reorganized, manner. Furthermore, the structural ensemble that we obtained enabled us to rationalize the results of tryptophan fluorescence experiments in the WT protein and a series of mutational variants. The results show that the integration of diverse sets of experimental data at relatively low structural resolution is a powerful approach that can provide insights into the structural organization of this conformationally heterogeneous three-helix intermediate with unprecedented detail and highlight the importance of both native and non-native interactions in stabilizing its structure.
Giα and Gβ subunits both define selectivity of G protein activation by α2-adrenergic receptors
Authors: Gibson Scott K. , Gilman Alfred G.
Published: December 2005

Previous studies of the specificity of receptor interactions with G protein subunits in living cells have relied on measurements of second messengers or other downstream responses. We have examined the selectivity of interactions between α2-adrenergic receptors (α2R) and various combinations of Giα and Gβ subunit isoforms by measuring changes in FRET between Giα–yellow fluorescent protein and cyan fluorescent protein–Gβ chimeras in HeLa cells. All combinations of Giα1, -2, or -3 with Gβ1, -2, or -4 were activated to some degree by endogenous α2Rs as judged by agonist-dependent decreases in FRET. The degree of G protein activation is determined by the combination of Giα and Gβ subunits rather than by the identity of an individual subunit. RT-PCR analysis and small interfering RNA knockdown of α2R subtypes, followed by quantification of radiolabeled antagonist binding, demonstrated that HeLa cells express α2a- and α2b-adrenergic receptor isoforms in a 2:1 ratio. Increasing receptor number by overexpression of the α2aR subtype minimized the differences among coupling preferences for Giα and Gβ isoforms. The molecular properties of each Giα, Gβ, and α2-adrenergic receptor subtype influence signaling efficiency for the α2-adrenergic receptor-mediated signaling pathway.
Programming of Time-to-Peak Force for Brief Isometric Force Pulses: Effects on Reaction Time
Authors: Schröter Hannes
Published: December 2005

According to the parallel force unit model (PFUM) the programming of an isometric force pulse requires the specification of the number of force units and force unit duration. The programming of a force pulse with minimal time-to-peak force is an exception, however, as force unit duration is limited by the minimal possible value, which should be easier to adjust than larger force unit durations. Therefore, the duration of the programming process should be shorter for these force pulses and hence should result in shorter reaction time (RT). Four experiments assessed this prediction using a response precueing procedure. In each experiment the participants produced isometric flexions with their left or right index finger, and time-to-peak force was manipulated within a block. The results are consistent with the predictions of PFUM. The results, however, are at variance with alternative accounts which assume that RT depends primarily on response duration or rate of force production.