bluuebunny/crossref_metadata_2025 huggingface dataset:
Native Salivary Chromosomes of Drosophila melanogaster: Retrospect and Prospect
Authors: J Hill Ronald
Published: November 2018

A method has been developed which, for the first time, allows the preparation of mappable cytological spreads of salivary chromosomes from D. melanogaster without exposure to acid fixatives. These isolated native chromosomes show the best preservation of ultrastructure observed to date-ribonucleoprotein particles may be seen to be organized in linear arrays in transcriptionally active puffs and the repeating nucleosome module is present. Native salivary chromosomes are proving useful for the localization of nuclear proteins both at the light microscope and ultrastructural levels. They display only background-level binding of antibodies specific for the Z-DNA conformation. However, Z-DNA immunoreactivity is activated by exposure to acid fixative, first in interbands and then in bands. The Z-conformation in the chromosomes is held in place by elastic torsional strain which appears in the DNA following acid fixation. Native D. melanogaster salivary chromosomes offer promise for enabling the probing of the chromatin of known genetic loci for properties dependent on the preservation of macromolecular integrity.
DNA Synthesis in Relation to Hyphal Branching and Wall Composition in Allomyces macrogynus
Authors: Youatt Jean
Published: November 2018

In A. macrogynus the first replication of DNA occurred after germination, at the time of the first branching of rhizoids. Before the second replication galactan in the wall exceeded the glucan content and was not firmly attached. After the second DNA replication hyphallengthening commenced with an increase in the content of glucan but the walls lacked rigidity. At the time of the third replication walls underwent a change which commenced at the hyphal tip and worked back to the rhizoids, converting the hyphae to a rigid, cylindrical shape. Branching commenced after the fourth replication of DNA. Multiple branching occurred when mature plants were transferred to glucose-histidine-methionine solution without further DNA synthesis. Hyphal branching was used to show that A. macrogynus was able to use methionine, methionine sulfoxide, methionine sulfone, sodium sulfide, cysteine, cystathionine and homocysteine but not cystine. Thioacetamide supported growth through many subcultures showing that A. macrogynus can synthesize its sulfur amino acids.
Capillary Blood Flow in the Endometrium and Myometrium of Conscious Sheep: Effect of Catheterization of Uterine Arteries
Authors: Brown BW , Fraser IS , Mattner PE
Published: November 2018

Measures of capillary blood flow in the uterine tissues of conscious ewes were obtained by the use of microspheres. Total uterine capillary blood flow was significantly greater (P < 0'01) at oestrus than at day 8 of the oestrous cycle [69' 5 � (s.e.m.) 11' 9, cf. 15' 3 � I' 2 ml min -1, n = 7], reflecting increases of a similar order in both the endometrium and the myometrium. At these stages of the oestrous cycle, endometrial capillary blood flow constituted 83' 6 and 80' 5%, respectively, of the total uterine capillary flow.
Effect of Erythrocyte Spectrin on Actin Self-Association
Authors: Tilley Leann , Ralston GB
Published: November 2018

The polymerization of pyrene-labelled skeletal muscle actin has been monitored in the presence of chromatographically purified spectrin dimers and tetramers. A small but consistent effect of spectrin binding on the critical concentration was observed for actin polymerized in the presence of 1 mM MgCI2. These data were analysed using the principle of linked functions.
A Rapid, Sensitive and Reliable Assay for Inhibin Bioactivity
Authors: WK Lee V , Colvin Noelene , Quigg Helen , Atley Lynne , McMaster Julie , Leversha Lorraine , Burger HG
Published: November 2018

A rapid 2-day quantitative assay for inhibin bioactivity based on FSH secretion from pituitary cells of immature female rats is described. The bioassay exhibited steeper slopes, improved precision and greater (fourfold) sensitivity compared with a previously established pituitary FSH cell content assay. Whole pituitary glands were used for the preparation of pituitary cells and the method for cell dispersion required a single enzymatic treatment with trypsin. Cells (180000 viable cells per well) were dispensed into culture media containing inhibin and incubated for 48 h. Media were removed and assayed for FSH by radioimmunoassay. Using a ram rete testis fluid preparation as standard the inhibin dose-response curves of 25 consecutive experiments showed indices of precision of - O� 08(mean)[range - 0�04 to - 0�17] and Finney's G values of 0�017[0�003-0�06]. The mean ED40 was 0�17 units of in hi bin activity per well with interassay variation of 16�2% at this point of the dose-response curve. The assay had a practical capacity of 400 wells, permitting the measurement of dose-response curves of at least 40 unknowns with three dose points and triplicate wells per dose. The assay is specific for inhibin-containing preparations from several animal species. Overall, the assay is simple, precise, and sensitive, indicative of its applicability to the measurement of inhibin samples with low inhibin bioactivity and to the screening of large numbers of fractions during inhibin purification.
Genome-level identification of cell wall invertase genes in wheat for the study of drought tolerance
Authors: Webster Hollie , Keeble Gabriel , Dell Bernard , Fosu-Nyarko John , Mukai Y. , Moolhuijzen Paula , Bellgard Matthew , Jia Jizeng , Kong Xiuying , Feuillet Catherine , Choulet Frédéric , International Wheat Genome Sequencing Consortium  , Appels Rudi
Published: November 2018

In wheat (Triticum aestivum L.) drought-induced pollen sterility is a major contributor to grain yield loss and is caused by the downregulation of the cell wall invertase gene IVR1. The IVR1 gene catalyses the irreversible hydrolysis of sucrose to glucose and fructose, the essential energy substrates which support pollen development. Downregulation of IVR1 in response to drought is isoform specific and shows variation in temporal and tissue-specific expression. IVR1 is now prompting interest as a candidate gene for molecular marker development to screen wheat germplasm for improved drought tolerance. The aim of this study was to define the family of IVR1 genes to enable: (1) individual isoforms to be assayed in gene expression studies; and (2) greater accuracy in IVR1 mapping to the wheat genetic map and drought tolerance QTL analysis. Using a cell wall invertase-specific motif as a probe, wheat genomics platforms were screened for the presence of unidentified IVR1 isoforms. Wheat genomics platforms screened included the IWGSC wheat survey sequence, the wheat D genome donor sequence from Aegilops tauschii Coss, and the CCG wheat chromosome 3B assembly: contig506. Chromosome-specific sequences homologous to the query motif were isolated and characterised. Sequence annotation results showed five previously unidentified IVR1 isoforms exist on multiple chromosome arms and on all three genomes (A, B and D): IVR1–3A, IVR1–4A, IVR1–5B, IVR1.2–3B and IVR1-5D. Including three previously characterised IVR1 isoforms (IVR1.1–1A, IVR1.2–1A and IVR1.1–3B), the total number of isoform gene family members is eight. The IVR1 isoforms contain two motifs common to cell wall invertase (NDPN and WECPDF) and a high degree of conservation in exon 4, suggesting conservation of functionality. Sequence divergence at a primary structure level in other regions of the gene was evident amongst the isoforms, which likely contributes to variation in gene regulation and expression in response to water deficit within this subfamily of IVR1 isoforms in wheat.
Component traits of plant water use are modulated by vapour pressure deficit in pearl millet (Pennisetum glaucum (L.) R.Br.)
Authors: Kholová Jana , Zindy Paul , Malayee Srikanth , Baddam Rekha , Murugesan Tharanya , Kaliamoorthy Sivasakthi , Hash C. Tom , Votrubová Olga , Soukup Aleš , Kočová Marie , Niang Mareme , Vadez Vincent
Published: November 2018

Traits influencing plant water use eventually define the fitness of genotypes for specific rainfall environments. We assessed the response of several water use traits to vapour pressure deficit (VPD) in pearl millet (Pennisetum glaucum (L.) R.Br.) genotypes known to differ in drought adaptation mechanisms: PRLT 2/89–33 (terminal drought-adapted parent), H 77/833–2 (terminal drought-sensitive parent) and four near-isogenic lines introgressed with a terminal drought tolerance quantitative trait locus (QTL) from PRLT 2/89–33 (ICMR01029, ICMR01031, ICMR02042, and ICMR02044). Plant water use traits at various levels of plant organisation were evaluated in seven experiments in plants exposed either transiently or over the long term to different VPD regimes: biomass components, transpiration (water usage per time unit) and transpiration rate (TR) upon transient VPD increase (g H2O cm–2 h–1)), transpiration efficiency (g dry biomass per kg H2O transpired), leaf expansion rate (cm per thermal time unit) and root anatomy (endodermis dimensions)). High VPD decreased biomass accumulation by reducing tillering, the leaf expansion rate and the duration of leaf expansion; decreased root endodermis cell size; and increased TR and the rate of TR increase upon gradual short-term VPD increases. Such changes may allow plants to increase their water transport capacity in a high VPD environment and are genotype-specific. Some variation in water use components was associated with terminal drought adaptation QTL. Knowledge of water use traits’ plasticity in growth environments that varied in evaporative demand, and on their genetic determinacy, is necessary to develop trait-based breeding approaches to complex constraints.
Contrasting the population genetic structure of two velvet worm taxa (Onychophora : Peripatopsidae : Peripatopsis) in forest fragments along the south-eastern Cape, South Africa
Authors: Daniels Savel R. , Dreyer Megan , Sharma Prashant P.
Published: November 2018

During the present study, we examined the phylogeography and systematics of two species of velvet worm (Peripatopsis Pocock, 1894) in the forested region of the southern Cape of South Africa. A total of 89 P. moseleyi (Wood-Mason, 1879) and 65 P. sedgwicki (Purcell, 1899) specimens were collected and sequenced for the cytochrome c oxidase subunit I mtDNA (COI). In addition, a single P. sedgwicki specimen per sample locality was sequenced for the 18S rRNA locus. Furthermore, morphological variation among P. sedgwicki sample localities were explored using traditional alpha taxonomic characters. DNA sequence data were subjected to phylogenetic analyses using Bayesian inference and population genetic analyses using haplotype networks and analyses of molecular variance (AMOVAs). Phylogenetic results revealed the presence of four and three clades within P. moseleyi and P. sedgwicki respectively. Haplotype networks were characterised by the absence of shared haplotypes between clades, suggesting genetic isolation, a result corroborated by the AMOVA and highly significant FST values. Specimens from Fort Fordyce Nature Reserve were both genetically and morphologically distinct from the two remaining P. sedgwicki clades. The latter result suggests the presence of a novel lineage nested within P. sedgwicki and suggests that species boundaries within this taxon require re-examination.
Gauge Explicit Quantum Mechanics and Perturbation Theory
Authors: Stewart A. M.
Published: November 2018

A version of quantum and statistical mechanics, including perturbation theory,
is described in which explicit electromagnetic gauge arbitrariness is
maintained at every stage. Any gauge may be used for a calculation provided
that the wave equation operator is gauge invariant.
'Hunting porcupines': citizen scientists contribute new knowledge about rare coral reef species.
Authors: Chin Andrew
Published: November 2018

There has been growing interest in engaging citizen scientists in the collection of environmental data to inform
conservation efforts and decision making, and to augment formal monitoring programmes. Citizen scientists can collect
data across large spatial and temporal scales that cannot be feasibly covered through traditional research and monitoring
programmes. The ‘Porcupine Ray Hunt’ was a pilot study that engaged the Australian recreational SCUBA diving
community in collecting information on the porcupine ray Urogymnus asperrimus, an easily identifiable but rare and
poorly understood species. ‘Crowd sourcing’ of recreational divers was achieved by advertising the programme through
diving publications, the internet, e-mail lists and social media (facebook and blogs). Dive clubs, dive shops and research
stations also advertised the project. Recreational divers were required to submit photographs and observations for
verification and 29 new valid records were received. Submissions also included video footage of foraging and mating
behaviour. The submissions received doubled the number of existing records on the species in Australia, identified
distribution ‘hot spots’, provided a depth range for the species and extended the species’ range. In doing so, the project
demonstrated the potential for citizen scientists to contribute valuable knowledge about rare species, addressing some
of the knowledge gaps concerning the porcupine ray and providing preliminary data for future research.
The Energy Loss Distributions of 1 MeV Electrons in Aluminium Foils
Authors: McDonell JA , Hanson MA , Wilson PR
Published: November 2018

The energy loss distributions for 1 MeV electrons traversing aluminium foils of various thicknesses have been investigated experimentally. Several of the foils were of thicknesses such that the distributions were expected to show considerable effects due to multiple scattering. It was found that the most probable energy losses were in good agreement with those predicted by the calculations of Hebbard and Wilson (1955).
Observations on the Penetrating Component of Extensive Air Showers
Authors: Officer VC , Eccles PJ
Published: November 2018

The variation in the composition of the penetrating component of extensive air showers at sea-level has been investigated as a function of shower density. The proportion of N-particles in the penetrating component was observed to decrease as the shower density decreased. It is suggested that this behaviour is due to the filtering action of the atmosphere on the more absorbable particles in the nuclear cascade which has passed maximum development.
Linear Superposition in Visco?Elasticity and Theories of Delayed Effects
Authors: Love ER
Published: November 2018

Writers on elastic after-working or "visco-elasticity" have given a formula expressing the stress-history as an integral involving the strain-history linearly. If this is to be based directly on experiment, linear superposition is a necessary physical datum; but it is not sufficient, and examples are given to demonstrate this. Necessary and sufficient conditions are established in this paper, and expressed in physical as well as in mathematical terms; they may admit physical verification in some degree. Histories both with and without beginning are considered.
The Scattering of 121 KeV Electrons and Positrons
Authors: Tassie LJ
Published: November 2018

The angular distribution of the single scattering of 121 keV positrons in gold and of 121 keV electrons and positrons in argon is calculated for an exponentially screened field. The single scattering distributions are integrated numerically to give mean square angles of multiple scattering, and hence the percentage difference in the r.m.s. angles of multiple scattering of electrons and positrons.
Abnormal Parity Solutions of the Wess-Zumino Consistency Conditions for Chiral SU(L)xSU(L) Symmetry
Authors: Christos GA
Published: November 2018

We obtain the general abnormal parity solutions of the Wess-Zumino consistency conditions for chiral SU(L)xSU(L) symmetry. We find an additional non-trivial solution which cannot be obtained from the usual Bardeen non-abelian anomaly through the addition of a local Lagrangian counter-term.
The Quantisation of the Screening Constant
Authors: J Miller Ian
Published: November 2018

Relationships are given in which the 'screening defect' is expressed in terms of the quantum numbers n and I for both the ground and excited states of neutral atoms for which the electron configuration can be considered as one electron and a core of completed shells. It is further shown that the same functions determine the ground-state energies for any series of neutral atoms with the same outer shell configuration. An explanation is offered in terms of wavefunctions with fewer nodes than the corresponding hydrogen wavefunctions.
Spatial Non-uniformity in Discharges in Low Pressure Helium and Neon
Authors: Fletcher J , Purdie PH
Published: November 2018

Low current, low pressure, steady state Townsend discharges in helium and neon gas have been investigated using the photon flux technique. Such discharges have been found to exhibit spatial non-uniformity resulting in luminous layers throughout the discharge. The separation and structure of these layers has been investigated experimentally in both gases along with the wavelength distribution of the photon flux. A Monte Carlo simulation of the discharge in neon has been used to gain information on the cross sections necessary to describe these discharges. It is found that direct excitaton of ground state atoms to the resonance level of each gas is less than indicated by some published cross section data.
Photons in Curved Space?Time
Authors: F Crawford David
Published: November 2018

Because photons are described by quantum mechanical wavefunctions that have a nonzero spatial extent it follows that they can be influenced by curved space-time. It is generally assumed that this tidal interaction is far too small to have a significant effect. This paper argues that there is a significant effect that results in an interaction between the photon and the material causing the curved space-time in which the photon loses energy to low energy secondary photons. The energy loss is a function of the space-time curvature and is proportional to distance. The only situation fully considered is that of a photon in curved space-time due to a uniform distribution of matter. Because the energy loss rate is very small it is difficult to observe in the laboratory and therefore its major applications are in astronomy. If the intergalactic density of matter is n hydrogen atoms m - 3, then the predicted value for the 'Hubble' constant (assuming no universal expansion) is 51�68 n1 /2 km s - 1 Mpc - 1. The theory can solve the virial mass discrepancy observed in clusters of galaxies and it makes a definite prediction about their relative magnitudes. Other astronomical applications are considered.
Application of Melnikov's Method to the Reduced KdV Equation
Authors: Roessler J
Published: November 2018

The Melnikov method for estimating distances between invariant manifolds is applied to the perturbed system of ordinary differential equations obtained from the KdV equation, reduced by a travelling wave ansatz and including a diffusion term. The calculation is performed after one integration and the result is compared with numerical work carried out on the full system.
Recent Developments in Nuclear Physics
Authors: EO Ericson Torleif
Published: November 2018

Nuclei exhibit features that are described in superficially contradictory terms according to the different degrees of freedom that are excited by probes of different scale in space and in time. After giving some examples I concentrate on the hadron degrees of freedom such as the nucleon, the pion and the .6. isobar. These are the effective degrees of freedom on the level of intermediate resolution: about 0�5-1 fm in distance and correspondingly in time. A prime example is the deuteron :which has a nearly model-independent description in terms of pion physics to very high precision. In nuclear matter the pion propagates in close analogy to the propagation of light in a dielectric. This permits the explanation of a number of features in nuclei related to the chiral symmetry limit in which the pion mass vanishes. A consequence of this description is the analogy of the equations for the pion and its effective field with the Maxwell equations for a dielectric. A pionic collective mode should appear strongly and with characteristic properties for a well chosen probe. It is difficult to explore its properties directly and in particular physical pions are not useful for this purpose. I will discuss different alternatives involving 'virtual pion beams'. There is recent evidence for such a collective state in forward charge exchange reactions throughout the periodic system.
Quantum Measurements in Atomic Optics
Authors: Walls DF , Collett MJ , Storey EP , Tan SM
Published: November 2018

We consider atoms traversing a cavity filled with an optical field. When the atoms are well detuned from the optical resonance the output momentum distribution of the atoms is found to be a sensitive probe of the photon statistics of the light field. Near resonance spontaneous emission smears the diffractive peaks. We obtain a good fit to the experimental data of Gould et at. (1991). As the atoms pass through the optical field they impart a position-dependent phase shift to the field. By making a quadrature phase measurement on the optical field a position measurement of the atom is achieved. We show that it is possible to prepare the atom in a 'contractive state' which beats the standard quantum limit for position measurements.
A Cyclic Symmetry Principle in Physics
Authors: Green HS
Published: November 2018

Many areas of modern physics are illuminated by the application of a symmetry principle, requiring the invariance of the relevant laws of physics under a group of transformations. This paper examines the implications and some of the applications of the principle of cyclic symmetry, especially in the areas of statistical mechanics and quantum mechanics, including quantized field theory. This principle requires invariance under the transformations of a finite group, which may be a Sylow 7r-group, a group of Lie type, or a symmetric group. The utility of the principle of cyclic invariance is demonstrated in finding solutions of the Yang-Baxter equation that include and generalize known solutions. It is shown that the Sylow 7r-groups have other uses, in providing a basis for a type of generalized quantum statistics, and in parametrising a new generalization of Lie groups, with associated algebras that include quantized algebras.
The Sigma Term: Leading Non-Analytic Behaviour Of Decuplet Contributions
Authors: Jameson I , Rawlinson AA , Thomas AW
Published: November 2018

We examine the analytic structure, in powers of the quark mass (m), of the chiral loop corrections to the pion-nucleon sigma term arising from coupling to the lowest mass baryon decuplet. The leading non-analytic term is found to go like m2 In(m/2a) (with a the delta-nucleon mass splitting), and to be quite significant numerically.
Distorted-wave Born and Impulse Approximations for Electron-Atom Ionisation
Authors: McCarthy IE
Published: November 2018

The distorted-wave Born and impulse approximations set the standard for the calculation of the ionisation of atoms by electrons. The approximations are derived from formal scattering theory. Their computational forms are given and a program for their numerical calculation is described. Input and output data are given for a trial run.
Radio Sources Observed with the Culgoora Circular Array
Authors: Slee OB
Published: November 2018

I present a final updated and recalibrated list of sources that were observed with the Culgoora circular array in the interval 1970~1984. The present list contains all the sources that were contained in the Culgoora-1, 2, 3 Lists plus additional sources resulting from a survey of 353 Abell clusters of galaxies. The electronic version of the Culgoora List, with appropriate documentation, is available from the Einstein On-Line Service.
Diffusion Monte Carlo Study of Electrons in Two-dimensional Layers
Authors: Rapisarda Francesco , Senatore Gaetano
Published: November 2018

We investigate the phase diagram of electrons in two dimensions at T = 0 by means of accurate diffusion Monte Carlo simulations within the fixed-node approximation. At variance with previous studies, we find that in an isolated layer Slater-Jastrow nodes yield stability of the fully polarised fluid at intermediate coupling, before freezing into a triangular crystal sets in. We have also studied coupled layers of electrons and of electrons and holes. Preliminary results show that at large coupling, as two layers are brought together from infinity, inter-layer correlation first stabilises the crystalline phase at distances of the order of the in-plane inter-particle spacing. As the distance is further decreased the effect of correlation, as expected, turns into an enhanced screening, which disrupts the crystalline order in favour of liquid phases.
Monte Carlo Investigation of Shot-noise Suppression in Nondegenerate Ballistic and Diffusive Transport Regimes
Authors: Reggiani L. , Reklaitis A. , González T. , Mateos J. , Pardo D. , Bulashenko O. M.
Published: November 2018

We review recent theoretical investigations of shot-noise suppression in
nondegenerate semiconductor structures surrounded by two contacts acting as
thermal reservoirs. Calculations make use of an ensemble Monte Carlo simulator
self-consistently coupled with a one-dimensional Poisson solver. By taking the
doping of the injecting contacts and the applied voltage as variable
parameters, the influence of elastic and inelastic scattering as well as of
tunneling between heterostructures in the active region is investigated. In
the case of a homogeneous structure at T = 300 K
the transition from ballistic to diffusive transport regimes under different
contact injecting statistics is analysed and discussed. Provided significant
space-charge effects take place inside the active region, long-range Coulomb
interaction is found to play an essential role in suppressing shot noise at
applied voltages much higher than the thermal value. In the elastic diffusive
regime, momentum space dimensionality is found to modify the suppression
factor γ, which within numerical uncertainty takes values respectively of
about ⅓, ½ and 0·7 in the 3D, 2D and 1D cases. In the
inelastic diffusive regime, shot noise is suppressed to the thermal value. In
the case of single and multiple barrier non-resonant heterostructures made by
GaAs/AlGaAs at 77 K, the mechanism of suppression is identified in the
carrier inhibition to come back to the emitter contact after having been
reflected from a barrier. This condition is realised in the presence of strong
inelastic scattering associated with emission of optical phonons. At
increasing applied voltages for a two-barrier structure, shot noise is
suppressed up to about a factor of 0·50 in close analogy with the
corresponding resonant barrier-diode. For an increasing number of barriers,
shot noise is found to be systematically suppressed to a more significant
level by following approximately a 1/(N + 1)
behaviour, N being the number of barriers. This
mechanism of suppression is expected to conveniently improve the
signal-to-noise ratio of these devices.
Time-dependent Quantum Waveguide Theory: A Study of Nano Ring Structures
Authors: Midgley S. , Wang J. B.
Published: November 2018

As electronic circuits get progressingly smaller to the nanometre scale, the
quantum wave nature of the electrons starts to play a dominant role. It is
thus possible for the devices to operate by controlling the phase of the
quantum electron waves rather than the electron density as in present-day
devices. This paper presents a highly accurate numerical method to treat
quantum waveguides with arbitrarily complex geometry. Based on this model, a
variety of quantum effects can be studied and quantified.
Exact causal bulk viscous stiff cosmologies.
Authors: Mak M. K. , Harko T.
Published: November 2018

An exact solution of the gravitational field equations is presented for a
homogeneous flat Friedmann-Robertson-Walker universe filled with a causal bulk
viscous fluid obeying the Zeldovich stiff equation of state and having bulk
viscosity coefficient proportional to the fourth root of the energy density.
Phase transition properties of a finite ferroelectric superlattice from the transverse Ising model.
Authors: Wang Xiao-Guang , Liu Ning-Ning , Pan Shao-Hua , Yang Guo-Zhen
Published: November 2018

We consider a finite ferroelectric superlattice in which the elementary unit
cell is made up of 1 atomic layers of type
A and n atomic layers of type
B. Based on the transverse Ising model we examine the
phase transition properties of the ferroelectric superlattice. Using the
transfer matrix method we derive the equation for the Curie temperature of the
superlattice. Numerical results are given for the dependence of the Curie
temperature on the thickness and exchange constants of the superlattice.
A Comparison of Potassium and Chloride Uptake by Tradescantia albiflora Leaf Cells at Different KCI Concentrations
Authors: Johansen C , Luttge U
Published: November 2018

Light stimulates K+ and Cl- uptake into T. albiflora leaf slices from solutions through which N*2 is bubbled, and not from aerated solutions, at KCl concentrations of 0.5, 5 and 20 mM. The metabolic inhibitors CCCP, DCMU and oligomycin affect K+ and Cl- uptake similarly at each of these KCl concentrations. The results suggest that both K+ and Cl- uptake under all conditions studied are driven by energy derived from a cytoplasmic pool of ATP. In aerobic solutions in the light ATP can be supplied by either oxidative phosphorylation or photophosphorylation while in N*2-bubbled solutions in the light non-cyclic photophosphorylation and possibly oxidative phosphorylation, utilizing photosynthetically evolved O*2, provide ATP. As Cl- uptake appears to be independent of K+ uptake, it is suggested that ion uptake by T. albiflora leaf cells may occur according to a mechanism which has been proposed for other green cells, where K+ and CI- are thought to exchange for H+ and OH- respectively.
Anatomy and Movement of The Column in Stylidium
Authors: Findlay G.P , Findlay N
Published: November 2018

The flower of the trigger-plant Stylidium has stamens and style fused into a single column. A bend in the column, upon suitable stimulation by nectar-gathering insects, reverses its curvature in 10-30 ms, depending on species, causing the column to flip rapidly through an angle of 2-5 radians from its normal position against the anterior modified petal, the labellum, until it comes to rest against the posterior petals. This rapid movement or 'firing' provides a mechanism for cross-fertilization of the flowers. The column, after this rapid excursion then slowly resets to its original position in times from 200 to 700 s. Detailed measurements of the time courses of firing and resetting in several species of Stylidium have been made. During the firing, except for a short period of 1-10 ms in which it accelerates from rest under a force up to 50 g, the column moves with approximately constant angular velocity. This characteristic linear behaviour contrasts markedly with the distinctly non-linear time course of resetting. The dependence of firing and resetting rates on temperature has been investigated.
A light-microscope study of the anatomy of the column shows that the mobile bend region possesses an internal anatomy strikingly different from the rest of the column. The bend consists of an inner core of three distinct longitudinal layers of thick-walled collenchymatous cells, surrounded by parenchymatous cells.
A model in which changes in length pf the anatomically posterior outer layer of the core are greater than in the other layers is proposed to account for the movement of the column.
Influence of Irradiance on H+ Efflux and Cl- Influx in Chara corallina: An Investigation Aimed at Testing Two Cl- Transport Models
Authors: Lucas W.J , Smith F.A
Published: November 2018

Parallel studies on the influence of irradiance on net H+ efflux and *36Cl- uptake were conducted on C. corallina. Following the dark-to-light transition, a lag period of 8-15 min was observed before net H+ efflux activity could be discerned experimentally. Decreasing the irradiance did not significantly lengthen this lag period. Studies on *36Cl- uptake revealed that a lag period of 40-60 min was required before the Cl- transport system attained maximum activity, governed by the prevailing experimental conditions.
These results are discussed in relation to the Cl- transport hypotheses proposed by Spear et al. and by Smith. It would seem that the hypothesis of Spear et al., in its present form, is invalid for Chara corallina. The results were inconclusive in terms of support (or otherwise) for a Cl-/OH- antiporter. However, the Cl-/OH- antiporter hypothesis originally proposed by Smith will require significant modification, especially in terms of the energy supply.
Effect of Oxygen and carbon Diozide Concentrations on Gross Dark CO2 Fixation and Dark Respiration in Bryophyllim diagremontiaum
Authors: Kaplan A , Gale J , Poljakoff-Mayber A
Published: November 2018

Effects of O2 and CO2 concentrations on the rates of net and gross dark CO2 fixation in B. daigremontianum were examined. Raising [CO2]i from 60 to 420 �ll-� resulted in a decrease in the rate of dark respiration, increase in the rate of gross dark fixation (GDF) and shortened the time taken to reach maximum rate of GDF. However, cumulative GDF was relatively unaffected by [CO2]i at that range. At 14�C, lowering [O2] from 21 to 1.5 % had little effect on the rates and time course of dark respiration and GDF. However, at 24�C, this caused a drop in the rate of dark respiration, changed the time dependence of GDF and slightly increased cumulative GDF. Consequently, at 24�C cumulative net CO2 uptake was 3 .3 times higher at 1 .5 % versus 21% O2. These data are discussed in view of the suggested hypothesis that the amount of available substrate, at the end of the light period, is a principal component of the regulation of the amount of gross dark fixation and dark respiration in the following dark period.
Transient Inhibition of Translocation in Ipomoea alba L. by Small Temperature Reductions
Authors: Pickard W.F , Minchin P.E.H , Troughton J.H
Published: November 2018

The response of translocation in I. alba to stepwise heating and cooling of 80-mm segments of stem was studied by pulse labelling with naturally loaded 11C. Translocation was indifferent to positive- going temperature steps within its normal physiological range; it was, however, momentarily disrupted by negative-going steps, even as small as that from 27.1�C to 21.4�C, i.e. 5.7�C.
Molecular Structure and Gibberellin Activity. II.* Further Studies on Helminthosporic Acid Analogues
Authors: Turner J.V , Mander L.N , Coombe B.G
Published: November 2018

The gibberellin-like activity of twelve synthetic helminthosporins has been examined in the barley endosperm bioassay. (�)-14-Norhelminthospor-7(12)-en-13-oic acid (5) was more potent than GA*9 and elicited similar responses in the assay measuring production of a-amylase, sugar and refractive compounds. Responses to acid (5) and GA*3 were retarded similary by abscisic acid. Log-doseresponse curves after 41 and 65 h incubation were of two types: linear with two C4-cyclohexyl helminthosporins and GA*3; and biphasic with two norhelminthosporins, showing initially a shallow curve then a steep slope at high concentrations. Structure-activity comparisons reveal that an alkyl group at C7 on a helminthosporin bridge contributes significantly to activity, but an olefinic bond has a minor effect. Three different orientations of the bridge carboxyl group did not materially alter activity. Oxygenated cyclohexyl helminthosporins had less biological activity than the deoxygenated analogue, perhaps reflecting a critical orientation of a hydroxyl group in the A ring of the more potent gibberellins.
Growth and Osmoregulation of Chlorella emersonii in NaCl and Neutral Osmotica
Authors: Setter T.L , Greenway H
Published: November 2018

Cell division of C. emersonii ceased for 21 h following transfer of cells from 1 to 335 mM NaCl [osmotic potential (�*s) = - 1.64 MPa], while the cells became bigger and the increase in volume of the algal material was reduced by only 30%.
After cells had grown for 5-8 days in 335 mM NaCl, relative growth rates for both cell numbers and protein were 30-40 % lower than in 1 mM NaCl. These adapted cells were about fourfold bigger, and contained 3-4.5 times more protein per cell, than cells grown in 1 mM NaCl.
Growth was reduced to a similar extent by NaCl and by slowly permeating mannitol and raffinose at a �*s of - 1.64 MPa. In contrast, rapidly permeating ethylene glycol (mol. wt 62) inhibited growth to a much smaller extent.
Cells grown in NaCl (at a �*s of - 1.64 MPa) accumulated proline and to a lesser extent sucrose. Proline and sucrose accumulation was the same in raffinose and NaCl, less in mannitol, and did not occur at all in cells grown in rapidly permeating ethylene glycol.
Thus, NaCl exerted few specific ion effects. Furthermore, growth reductions and accumulation of proline and sucrose were somehow related to the required osmoregulation, i.e. the control of turgor potential and/or volume, rather than to low internal water potentials.
NaCl did not affect starch levels and exogenous glucose and glutamate did not stimulate growth of cells adapted to 335 mM NaCl. Thus, the growth reductions were presumably due to a restraint on the metabolic machinery, rather than to a lack of organic carbon and nitrogen sources.
Accumulation of Proline and Sucrose during the First Hours after Transfer of Chlorella emevsonii to High NaCl
Authors: Greenway H , Setter T.L
Published: November 2018

Net synthesis of proline, the main osmotic solute in C. emersonii, showed a lag of at least 15 min
following transfer of cells from 1 m~ NaCl to concentrations ranging between 25 and 335 m~ NaCl.
During the subsequent period of rapid net proline synthesis, the maximum rates were approximately
linearly related to the decreases in external osmotic potential (YJ until the cells plasmolysed. Beyond
the point of incipient plasmolysis, further large decreases in Y* did not change the maximum rates
of proline synthesis. The steady-state levels of proline were lower, and were reached faster, the
smaller the decreases in external Ys. Overall these results support the notion that turgor potential
has a regulating role in the synthesis of osmotic solutes.
Sucrose synthesis showed no lag and was rapid even in plasmolysed cells.
Cycloheximide inhibited formation of proline but not of sucrose. This, together with the lag
phase of 15 min in proline synthesis, indicated that transfer of C. emersonii to high NaCl induced
de novo synthesis of enzymes involved in proline formation.
Effects of DCMU and darkness were also measured. Cells transferred to 125 m~ NaCl still
showed substantial net synthesis of sucrose, but not of proline. Supply of glucose in the dark did
not lead to proline formation, but it did stimulate proline synthesis which occurred when glutamate
was supplied.
Nitrate Reduction by a Dicarboxylate Shuttle in a Reconstituted System from Spinach Leaves
Authors: Woo K.C , Jokinen Mark , Canvin D.T
Published: November 2018

A reconstituted system of supernatant and mitochondria from spinach leaves reduced NO3- in
the presence of NAD+. A faster rate (2-6 times) of NO3- reduction was obtained when oxaloacetate
(OAA) and glycine were present. The reduction of NO3- in the presence of OAA and glycine was
sensitive to inhibition by n-butyl malonate, suggesting that the dicarboxylate exchange carrier was
involved in the transport of malate out of the mitochondria. The capacity of the dicarboxylate
shuttle to reduce NO,- was 63 % that of the in vitvo nitrate reductase activity in the supernatant
Effect of Cytokinins on the Expansion and Metabolism of Excised Cucumber Cotyledons
Authors: Tsui C , Guo-qing Tao , Hui-ying Chen , Yan-ru Son , Han-ping Lian , Zhe Tong , Shu-huan Li , Xian-zhang Li
Published: November 2018

Expansion of excised cucumber (Cucumis sativus L.) cotyledons was stimulated by treatment with
cytokinin, and commenced after a lag period of about 4 h.
Expansion induced by benzyladenine (BA) was due mainly to increase of fresh weight, but cell
number increased slightly. Hydrolysis of protein and lipid was stimulated by BA, and soluble
sugars increased simultaneously. However, there was no significant change in the dry weight of
cotyledons during the period of expansion. It is assumed that the transformation of lipid to sugar
in the cotyledon is stimulated by BA. The respiration of cotyledons was evidently stimulated by
BA and was entirely inhibited by respiratory inhibitors, e.g. NaN,, malonate and dinitrophenol.
Inhibitors of protein and nucleic acid synthesis, such as chloramphenicol and actinomycin D,
inhibited only the BA-induced expansion. They had no effect on the expansion of controls. These
results suggest that different biochemical processes are involved in the expansion of cotyledons
induced by BA and in controls. The former is related not only to respiration but also to the synthesis
of protein and nucleic acid. BA increased DNA and RNA content per cotyledon. The increase
of total RNA is due mainly to the increase of 25 S and 18 S rRNA.
Respiration-dependent Movements of the Column of Stylidium gvaminifolium
Authors: Findlay G.P , Findlay N
Published: November 2018

The column of the trigger plant, Stylidium graminifolium, when fully set responds to mechanical
stimuli by flipping through an angle of about 4 radians in a fast firing movement lasting about
15-30 ms, and then slowly resetting to its original position in about 400 s. After resetting there is an
absolute refractory period of about 500 s during which no further response to stimuli can be initiated,
followed by a relative refractory period when graded responses increasing in rate and magnitude
with time can be obtained. The resetting movement and the process, occurring during the refractory
period, allowing subsequent firing to occur, are inhibited when the air surrounding the column is
replaced by nitrogen. The firing movement, however, is not affected by these anaerobic conditions.
Thus the firing movement is caused by passive physical forces, rapidly utilizing potential energy
from a store built up during the previous resetting and refractory periods. Removal of the labellum,
which the column touches when set, causes the column to oscillate with amplitude of about 3-3.5
radians and period of 1-2 ks. When the column is held at a constant angular displacement it develops
an oscillatory torque with similar period. These oscillations are inhibited at all stages of the cycle
by anaerobic conditions. It appears that the oscillatory behaviour is not a slowed-down firing process
followed by normal resetting, but is linked throughout the cycle to the metabolic energy supply.
Proline, Betaine and Other Organic Solutes protect Enzymes against Heat Inactivation
Authors: Paleg L.G , Douglas T.J , van Daal A , Keech D.B
Published: November 2018

Proline and betaine, in a concentration-dependent manner, protect several different enzymes with
a wide range of thermal sensitivities, and from different sources, against the in vitvo inactivating
effects of heat. Since a number of solutes (D-proline, hydroxyproline, glycine, valine and glycerol),
in addition to proline and betaine, demonstrate this effect, it is concluded that the interaction between
solute and enzyme protein is a general one with respect to both effector and receptor molecules.
The nature of the response is unknown, although it may be related to the maintenance of conformational
characteristics and integrity of the proteins by the solutes.
Phosphate Uptake by Spirodela and Lemna during Early Phosphorus Deficiency
Authors: McPharlin I.R , Bieleski R.L
Published: November 2018

Growth, internal P concentration and Pi uptake was investigated in sterile cultures of Spirodela oligorrhiza (Kurz) Hegelm. and Lemna major L. plants during early P-deficiency. Within 12 h of transfer to a P-deficient medium, Pi uptake rates by P-deficient (- P) plants were enhanced 30-120% compared with P adequate (+ P) controls at 1-1000 �M external [Pi]. The enhancement in Pi uptake rates with P-deficiency normally preceded, and was more pronounced than, other effects of P-deficiency such as reduced growth, reduced internal [P] and appearance of visual symptoms. Enhanced Pi uptake rates in - P compared with +P plants resupplied with Pi was more closely correlated with a fall in the internal [Pi] (r = -0.93 to -0.98) than with a fall in the concentration of three other P fractions (i.e. ester P, lipid P, and residual P). The role of tissue [Pi] in Spirodela and Lemna plants as a possible determinant of Pi uptake rates is discussed. Kinetic analysis showed that enhanced Pi uptake in -P compared with + P plants resupplied with Pi was the result of a 2-4-fold increase in V*max of two first- order systems and not by an increased affinity (i.e. reduced K*m) of the carrier for the phosphate ion.
Editorial: Reflections on the Porous Boundaries of Primary Care
Authors: Walker Rae
Published: November 2018

In this issue of the Australian Journal of Primary Health we publish a typically diverse set of papers. The diversity leads into reflections on how well we address diversity in the field and where we should consider casting a little more light.
The Challenges of Recruiting and Retaining GPs in Research: Findings from a Smoking Cessation Project
Authors: McKay-Brown Lisa , Borland Ron , Balmford James , J Segan Catherine , Andrews Catherine , Tasker Caroline , Piterman Leon
Published: November 2018

This paper uses process evaluation to describe the challenges faced in recruiting and retaining general practitioners (GPs) into a smoking cessation Randomised Controlled Trial (RCT) that tested "in-practice" versus "referral to the Quitline" delivery of national smoking cessation guidelines within general practice. GPs expressed interest in participating in the research either through Divisions of General Practice or through a targeted mail-out to localised networks. The project aimed to recruit and retain 60 GPs. Initially 111 GPs expressed interest in the project, with 44 GPs (40% of those expressing interest) taking part. Using localised networks provided a higher rate of interest than using Divisions of General Practice. GPs allocated to the in-practice condition were more likely to withdraw from the project (46% vs. 30%). The main reason GPs cited when withdrawing from the project was that they were "too busy to recruit". Recruiting and retaining GPs to smoking cessation research is an ongoing challenge with multiple recruitment strategies needed and considerable effort required to ensure GPs comply with the requirements of the research. Barriers to recruitment and retention are of concern and can significantly affect the implementation of large-scale research projects.