A preliminary survey of Chlamydia psittaci genotypes from native and introduced birds in New Zealand

AIM: To describe the Chlamydia psittaci genotypes in samples from native and introduced birds from New Zealand by analysis of the sequence variation of the ompA gene.

METHODS: DNA was extracted from samples collected from a non-random sample of birds; either swabs from live asymptomatic birds or birds with clinical signs, or formalin-fixed, paraffin-embedded (FFPE) samples from historical post-mortem cases. The presence of C. psittaci in all samples had been confirmed using a quantitative PCR assay. The C. psittaci ompA gene was amplified and sequenced from samples from 26 native and introduced infected birds comprising 12 different species. These sequences were compared to published available C. psittaci genotypes.

RESULTS: Genotypes A and C of C. psittaci were identified in the samples. Genotype A was identified in samples from nine birds, including various native and introduced species. Genotype C was identified in samples from 16 different waterfowl species, and a mixed infection of both genotypes was found in a kaka (Nestor meridionalis). In native birds, C. psittaci infection was confirmed in seven new host species.

CONCLUSIONS AND CLINICAL RELEVANCE: Two genotypes (A and C) of C. psittaci were found in samples from a wider range of both native and introduced species of birds in New Zealand than previously reported. Both genotypes have been globally associated with significant disease in birds and humans. These initial results suggest the host range of C. psittaci in New Zealand birds is under-reported. However, the prevalence of C. psittaci infection in New Zealand, and the associated impact on avian and public health, remains to be determined. There are biosecurity implications associated with the importation of birds to New Zealand if there is a limited diversity of C. psittaci genotypes present.     

Phytoplankton community structure and the drawdown of nutrients and CO2 in the southern ocean

Data from recent oceanographic cruises show that phytoplankton community structure in the Ross Sea is related to mixed layer depth. Diatoms dominate in highly stratified waters, whereas Phaeocystis antarctica assemblages dominate where waters are more deeply mixed. The drawdown of both carbon dioxide (CO2) and nitrate per mole of phosphate and the rate of new production by diatoms are much lower than that measured for P. antarctica. Consequently, the capacity of the biological community to draw down atmospheric CO2 and transport it to the deep ocean could diminish dramatically if predicted increases in upper ocean stratification due to climate warming should occur.     

Comparison of homozygous and heterozygous self-compatible seedlings in an almond breeding programme

Homozygous self-compatible almond cultivars have not been reported. It is unclear if they are more inferior than heterozygotes or simply have not yet been detected. To investigate if homozygous individual are generally inferior, the self-compatibility genotype, homozygous or heterozygous, was determined by stylar ribonuclease assay in a population of 241 almond trees obtained by self-fertilisation of self-compatible selections. The resulting zymograms showed that 129 of the seedlings were homozygous and 112 heterozygous. For three years the differences observed between these two classes of self-compatible individuals were analysed with respect to 16 agronomic characteristics. In general, there were no important differences between the two classes. Both showed a low degree of productivity, probably as a result of their inbred origin. Some selected homozygous individuals were used in crosses, which were planned so as to ensure the self-compatibility of 100% of the descendants and to eliminate the laborious task of testing the seedlings for self-compatibility. This revised version was published online in August 2006 with corrections to the Cover Date.     

Combining apetalous parthenocarpy with columnar growth habit in apple

Summary ‘Wijcik’, a sport of ‘McIntosh’ with columnar growth habit, was crossed with ‘Wellington Bloomless’, which has apetalous flowers and bears parthenocarpic seedless fruit if not pollinated. The seedlings segregated for columnar versus normal habit but all had normal flowers and fruit. Four columnar seedlings were crossed with ‘Spencer Seedless’, another apetalous cultivar, and the resulting seedlings segregated not only for plant habit but also for apetalous versus normal flowers, approximately 1 : 1. Thus apetaly is controlled by a recessive gene, for which the symbolape is proposed. Apetalous columnar apples may be useful for planting in very high density orchards, cropping without pollination and thus not dependent on bees, pollinator varieties and warm weather at flowering time; moreover, being seedless they may avoid biennial bearing tendencies that are attributable to developing seeds inhibiting fruit bud formation.     

Carbonic acid in the gas phase and its astrophysical relevance

In outer space, high-energy irradiation of cryogenic ice mixtures of abundant water and carbon dioxide is expected to form solid carbonic acid. Experiments and thermodynamic analyses show that crystalline carbonic acid sublimates without decomposition. Free-energy considerations based on highly accurate molecular quantum mechanics, in combination with vapor pressures resulting from experimental sublimation rates, suggest that in the gas phase, a monomer and dimer of carbonic acid are in equilibrium, comparable to that of formic acid. Gaseous carbonic acid could be present in comets, on Mars and outer solar system bodies, in interstellar icy grains, and in Earth's upper atmosphere.     

Pathogenicity and virulence of south African isolates of Venturia inaequalis

European Journal of Plant Pathology - Many abiotic and biotic factors can negatively affect the production and productivity of coconut cropping systems. The incidence of Lasiodiplodia species in...     

Microclimate modifications,growth and yield of intercrops under Hardwickia binata Roxb. based agroforestry system

An experiment was conducted by planting Hardwickia binata Roxb. at 200, 400 and 800 trees ha^???1, intercrops viz., Brassica campestris (mustard) and Glycine max (soybean) were sown from the second year onwards in winter and summer respectively at the National Research Centre for Agroforestry, Jhansi, U.P., India with the objectives of evaluating agrosilvicultural potential of the system and to study the effect of tree densities on ecophysiology of understorey crops. Tree growth was affected by both density and intercrop in the initial years of growth. Photosynthetic photon flux density (PPFD) available to the intercrops reduced with increasing densities. Transpiration rate and stomatal conductance in intercrops decreased due to the presence of trees. No significant changes in leaf temperature were observed till the fifth year of the growing season. Yield was significantly higher in pure crop in comparison with all the densities in mustard. Soybean yield under 200 trees ha^???1 was comparable to that of the pure crop. Trees at the density of 200 trees ha^???1 provided a conducive microenvironment to the intercrops.     

Correlation of ribonuclease zymograms and incompatibility genotypes in almond

Proteins were extracted from styles of 29 self-incompatible cultivars of almond and separated using non-equilibrium pH gradient electro-focusing, and the gels were stained for ribonuclease activity. Mutually incompatible cultivars had similar banding patterns and, for the 24 cultivars already genotyped in France or California, the bands correlated well with the reported alleles. The band corresponding to S₁ of the French labelling system was indistinguishable from that corresponding to S_b of the Californian labelling system, and a controlled cross confirmed that these alleles are identical. The band corresponding to the Californian S_a was distinct from the bands corresponding to French alleles and, to harmonise the allele labels, it was redesignated S₅. The genotypes of five uncharacterised self-incompatible cultivars were inferred from zymograms as follows: ‘Desmayo Largueta’ and ‘Glorieta’, S₁S₅, ‘Masbovera’, S₁S₉, ‘Tarragones’, S₂S₉, and ‘Tokyo’, S₆S₇. The alleles designated S₆ and S₉ have not previously been reported. Nine self-compatible cultivars or selections were analysed, and each showed a band corresponding to an incompatibility allele as well as a common band; however, the correspondence of this common band to S_f, the allele for self-compatibility, is unproven. This revised version was published online in July 2006 with corrections to the Cover Date.     

The European Prunus mapping project Progress in the almond linkage map

Summary Six European research groups are collaborating to develop genetic markers and linkage maps for use inPrunus breeding programmes. A basic map with 200 RFLPs and 50 more markers including isozymes and RAPDs will be constructed using two highly segregating populations: an interspecific peach × almond F₂ and a cherry F₂. Then, the parents of eleven almond, cherry, peach or plum breeding progenies segregating for target characters will be screened for polymorphisms at the marker loci, and a set of reduced maps, one per progeny, will be constructed with markers spaced 20–30 cM and covering the whole genome. Cosegregation analysis of markers and characters of interest will allow us to find linkages between markers and major genes or quantitative trait loci responsible for the expression of these traits. A map with 72 markers, 7 isozymes and 65 RFLPs, has been developed at the IRTA-Cabrils laboratory using an intraspecific almond progeny, ‘Ferragnes’ × ‘Mono’. Probes for the analysis of RFLPs were obtained from almond genomic and cDNA libraries. The level of polymorphism for RFLPs and the distribution of markers in the chromosomes of almond are discussed.