Productivity, carbon assimilation and intra-annual change in tropical reef platform seagrass communities of the Torres Strait, north-eastern Australia

Detailed data on seagrass distribution, abundance, growth rates and community structure information were collected at Orman Reefs in March 2004 to estimate the above-ground productivity and carbon assimilated by seagrass meadows. Seagrass meadows were re-examined in November 2004 for comparison at the seasonal extremes of seagrass abundance. Ten seagrass species were identified in the meadows on Orman Reefs. Extensive seagrass coverage was found in March (18,700 ha) and November (21,600 ha), with seagrass covering the majority of the intertidal reef-top areas and a large proportion of the subtidal areas examined. There were marked differences in seagrass above-ground biomass, distribution and species composition between the two surveys. Major changes between March and November included a substantial decline in biomass for intertidal meadows and an expansion in area of subtidal meadows. Changes were most likely a result of greater tidal exposure of intertidal meadows prior to November leading to desiccation and temperature-related stress. The Orman Reef seagrass meadows had a total above-ground productivity of 259.8 t DW day-1 and estimated carbon assimilation of 89.4 t C day-1 in March. The majority of this production came from the intertidal meadows which accounted for 81% of the total production. Intra-annual changes in seagrass species composition, shoot density and size of meadows measured in this study were likely to have a strong influence on the total above-ground production during the year. The net estimated above-ground productivity of Orman Reefs meadows in March 2004 (1.19 g C m-2 day-1) was high compared with other tropical seagrass areas that have been studied and also higher than many other marine, estuarine and terrestrial plant communities.

High-resolution melt-curve analysis of random amplified polymorphic DNA (RAPD-HRM) for the characterisation of pathogenic leptospires: intra-serovar divergence, interserovar convergence, and evidence of attenuation in Leptospira reference collections.

High-resolution melt-curve analysis of random amplified polymorphic DNA (RAPD-HRM) is a novel technology that has emerged as a possible method to characterise leptospires to serovar level. RAPD-HRM has recently been used to measure intra-serovar convergence between strains of the same serovar as well as inter-serovar divergence between strains of different serovars. The results indicate that intra-serovar heterogeneity and inter-serovar homogeneity may limit the application of RAPD-HRM in routine diagnostics. They also indicate that genetic attenuation of aged, high-passage-number isolates could undermine the use of RAPD-HRM or any other molecular technology. Such genetic attenuation may account for a general decrease seen in titres of rabbit hyperimmune antibodies over time. Before RAPD-HRM can be further advanced as a routine diagnostic tool, strains more representative of the wild-type serovars of a given region need to be identified. Further, RAPD-HRM analysis of reference strains indicates that the routine renewal of reference collections, with new isolates, may be needed to maintain the genetic integrity of the collections.

Stem injection: a control technique often overlooked for exotic woody weeds

In the rangelands of northern Australia, basal bark, cut stump, hand applied residual herbicides and foliar spraying have traditionally been the main herbicide techniques for control of individual exotic woody weeds growing within scattered to medium density infestations. In this paper we report on the preliminary results of stem injection as an alternate technique for the control of yellow oleander ( Cascabela thevetia (L.) Lippold), a woody weed that is difficult to kill. A randomised complete block experiment comprising 12 herbicide treatments (including a control) and three replicates was undertaken. Two rates of triclopyr + picloram, hexazinone, glyphosate, 2,4- D + picloram and metsufuron methyl and one rate of imazapyr were tested. At 15 months after application, triclopyr + picloram, glyphosate, 2,4-D + picloram and imazapyr all recorded high mortality (>90%) for at least one application rate. These results suggest that stem injection warrants further investigation as a control technique for other exotic woody weeds growing in rangelands.

Rapid microsatellite marker development for African mahogany ( Khaya senegalensis, Meliaceae) using next-generation sequencing and assessment of its intra-specific genetic diversity.

Khaya senegalensis (African mahogany or dry-zone mahogany) is a high-value hardwood timber species with great potential for forest plantations in northern Australia. The species is distributed across the sub-Saharan belt from Senegal to Sudan and Uganda. Because of heavy exploitation and constraints on natural regeneration and sustainable planting, it is now classified as a vulnerable species. Here, we describe the development of microsatellite markers for K. senegalensis using next-generation sequencing to assess its intra-specific diversity across its natural range, which is a key for successful breeding programs and effective conservation management of the species. Next-generation sequencing yielded 93943 sequences with an average read length of 234bp. The assembled sequences contained 1030 simple sequence repeats, with primers designed for 522 microsatellite loci. Twenty-one microsatellite loci were tested with 11 showing reliable amplification and polymorphism in K. senegalensis. The 11 novel microsatellites, together with one previously published, were used to assess 73 accessions belonging to the Australian K. senegalensis domestication program, sampled from across the natural range of the species. STRUCTURE analysis shows two major clusters, one comprising mainly accessions from west Africa (Senegal to Benin) and the second based in the far eastern limits of the range in Sudan and Uganda. Higher levels of genetic diversity were found in material from western Africa. This suggests that new seed collections from this region may yield more diverse genotypes than those originating from Sudan and Uganda in eastern Africa.

Effect of physiological and experiential state of Bactrocera tryoni flies on intra-tree foraging behavior for food (bacteria) and host fruit

Using caged guava trees in Queensland, Australia, provided with food and oviposition sites, the foraging behaviour of females of the tephritid Bactrocera tryoni was investigated in relation to hunger for protein, the presence or absence of bacteria as a source of protein, the degree of prior experience with host fruit and quality of host fruit for oviposition. One aim was to evaluate whether it is immature or mature B. tryoni females that are responsible for initially inoculating host fruit surfaces with "fruit-fly-type" bacteria, the odour of which is known to attract B. tryoni females. Three-week-old immature females provided with sucrose but deprived of protein from eclosion had a much greater propensity than 3-week-old protein-fed mature females to visit vials containing fruit-fly-type bacteria, irrespective of whether vials were associated with adjacent host fruit or not. In the absence of associated bacteria in vials, immature females had a much lower propensity than mature females to visit host fruit. In the presence of bacteria in vials, however, propensity of immature and mature females to visit fruit was about equal. Mature (but not immature) females were more inclined to visit fruit that ranked higher for oviposition (nectarines) than fruit that ranked lower (sweet oranges). Mature females that attempted oviposition during a single 3-min exposure period to a nectarine prior to release were much more likely to find a nectarine than were mature females naive to fruit or immature females with or without prior contact with fruit. Exposure to a nectarine before release did not affect the propensity of either mature or immature females to alight on an odourless visual model of a nectarine, however. As judged by numbers of leaves visited, protein-deprived immature females were more active than protein-fed mature females, irrespective of the sorts of resources on a tree. It was concluded that: the 1st B. tryoni females to arrive on the fruit of a host tree and therefore inoculate the fruit with fruit-fly-type bacteria were unlikely to be sexually immature, but to be mature as a result of having earlier acquired protein elsewhere; the odour of colonies of fruit-fly-type bacteria when associated with host fruit attracted protein-hungry but not protein-fed females; and the odour of the fruit itself attracted mature females (especially experienced ones) but not immature females.

Follicle stimulating hormone secretion and dominant follicle growth during treatment of Bos indicus heifers with intra-vaginal progesterone releasing devices, oestradiol benzoate, equine chorionic gonadotrophin and prostaglandin F-2 alpha

The aim of this study was to investigate the effects on follicle stimulating hormone (FSH) secretion and dominant follicle (OF) growth, of treatment of Bos indicus heifers with different combinations of intra-vaginal progesterone releasing devices (IPRD), oestradiol benzoate (ODB), PGF(2 alpha), and eCG. Two-year-old Brahman (BN; n=30) and Brahman-cross (BNX; n=34) heifers were randomly allocated to three IPRD-treatments: (i) standard-dose IPRD [CM 1.56 g; 1.56 g progesterone (P-4); n = 17]; (ii) half-dose IPRD (CM 0.78 g; 0.78 g p(4); n=15); (iii) half-dose IPRD + 300 IU eCG at IPRD removal (CM 0.78 g+G; n=14); and, (iv) non-IPRD control (2 x PGF(2 alpha); n=18) 500 mu g cloprostenol on Days -16 and -2. IPRD-treated heifers received 250 mu g PGF(2 alpha) at IPRD insertion (Day 10) and IPRD removal (Day -2) and 1 mg ODB on Day -10 and Day -1. Follicular dynamics were monitored daily by trans-rectal ultrasonography from Day -10 to Day 1. Blood samples for determination of P-4 were collected daily and samples for FSH determination were collected at 12 h intervals from Day -9 to Day -2. A significant surge in concentrations of FSH was observed in the 2 x PGF(2 alpha), treatment 12 h prior and 48 h after follicular wave emergence, but not in the IPRD-treated heifers. Estimated mean concentrations of total plasma P-4 during the 8 days of IPRD insertion was greater (P<0.001) in the CM 1.56 g P-4 treated heifers compared to the CM 0.78 g P-4 treated heifers (18.38 ng/ml compared with 11.09 ng/ml, respectively). A treatment by genotype interaction (P=0.036) was observed in the mean plasma P4 concentration in heifers with no CL during IPRD insertion, whereby BN heifers in the CM 1.56 g treatment had greater plasma P-4 than the BNX heifers on Days-9, -7, -6, -5, and -4. However, there was no genotype effect in the CM 0.78 g +/- G or the 2 x PGF(2 alpha) treatment. Treatment had no effect on the DF growth from either day of wave emergence (P=0.378) or day of IPRD removal (P=0.780) to ovulation. This study demonstrates that FSH secretion in B. indicus heifers treated with a combination of IPRD's and ODB to synchronise ovulation was suppressed during the period of IPRD insertion but no significant effect on growth of the DF was observed. (C) 2013 Elsevier B.V. All rights reserved.

Molecular diversity of Chickpea chlorotic dwarf virus in Sudan: High rates of intra-species recombination – a driving force in the emergence of new strains

In Sudan Chickpea chlorotic dwarf virus (CpCDV, genus Mastrevirus, family Geminiviridae) is an important pathogen of pulses that are grown both for local consumption, and for export. Although a few studies have characterised CpCDV genomes from countries in the Middle East, Africa and the Indian subcontinent, little is known about CpCDV diversity in any of the major chickpea production areas in these regions. Here we analyse the diversity of 146 CpCDV isolates characterised from pulses collected across the chickpea growing regions of Sudan. Although we find that seven of the twelve known CpCDV strains are present within the country, strain CpCDV-H alone accounted for ∼73% of the infections analysed. Additionally we identified four new strains (CpCDV-M, -N, -O and -P) and show that recombination has played a significant role in the diversification of CpCDV, at least in this region. Accounting for observed recombination events, we use the large amounts of data generated here to compare patterns of natural selection within protein coding regions of CpCDV and other dicot-infecting mastrevirus species.