Agricultural landscape modification increases the abundance of an important food resource: Mistletoes, birds and brigalow

Agricultural landuse alters landscape pattern, with important consequences for native species. Complex responses to changes in landscape pattern may be observed for species with strong inter-specific relationships. We investigate how the abundance of an ecologically important food resource, the grey mistletoe (Amyema quandang), is influenced by the interactive influences of human-modified landscape pattern, bird disperser abundance and host condition. Mistletoe abundance was estimated in brigalow (Acacia harpophylla) dominated remnants in three separate study areas with differing landscape patterns. Negative binomial generalised linear models of mistletoe abundance were tested with combinations of seven explanatory variables: study area, landscape connectivity and edge contrast, patch shape, bird disperser abundance, brigalow foliage cover and basal area of standing dead trees. Ranking of model averaged parameter estimates showed that study area, bird disperser abundance, patch shape, dead trees and connectivity had the strongest influence on A. quandang abundance. Mistletoe abundance apparently increased with landscape modification, particularly in narrow linear patches, but may be limited by the availability of seed dispersers and host condition. Given high landscape modification and ongoing degradation, management should be targeted towards maintaining brigalow remnant condition to ensure bird and mistletoe populations can be supported in the long-term.     

The age and amount of regrowth forest in fragmented brigalow landscapes are both important for woodland dependent birds

In highly-modified agricultural landscapes, regrowth (secondary) forest on abandoned farmland offers the potential for passive landscape restoration for biodiversity conservation. While numerous studies have investigated the ecological values of regrowth for fauna recovery at the local-level (1-10 ha), there is a dearth of studies quantifying the contribution of regrowth forest at the landscape-level (100-1000s ha). To address this critical knowledge gap we question how the age and amount of regrowth forest in the landscape influence species richness and abundance of mature forest dependent species? Using woodland dependent birds in fragmented sub-tropical brigalow landscapes in southern Queensland, Australia, we applied model averaging and hierarchical partitioning analyses to test and rank the relative importance of the amount of regrowth forest in the landscape in three age classes (<15, 15-30, and >30 years) compared to local (grazing disturbance, abundance of aggressive miners, mistletoe abundance and patch age) and landscape measures of habitat (amount of mature forest and number of mature forest patches). Response variables included the species richness of woodland dependent birds and sub-groupings of foraging guilds, and the abundance of selected individual species. The importance of explanatory variables differed considerably among response groups. Local attributes, such as patch age and the abundance of mistletoe plants, had the strongest influences on woodland dependent birds. However, we found that the amount of regrowth forest, particularly >30 years, also had a strong influence on both species richness and abundance. This study confirms that regrowth, especially older regrowth, can make an important contribution to landscape restoration in highly-modified agricultural landscapes.     

Cinnamon bark proanthocyanidins as reactive carbonyl scavengers to prevent the formation of advanced glycation endproducts

Cinnamon bark has been reported to be effective in the alleviation of diabetes through its antioxidant and insulin-potentiating activities. In this study, the inhibitory effect of cinnamon bark on the formation of advanced glycation endproducts (AGEs) was investigated in a bovine serum albumin (BSA)-glucose model. Several phenolic compounds, such as catechin, epicatechin, and procyanidin B2, and phenol polymers were identified from the subfractions of aqueous cinnamon extract. These compounds showed significant inhibitory effects on the formation of AGEs. Their antiglycation activities were not only brought about by their antioxidant activities but also related to their trapping abilities of reactive carbonyl species such as methylglyoxal (MGO), an intermediate reactive carbonyl of AGE formation. Preliminary study on the reaction between MGO and procyanidin B2 revealed that MGO-procyanidin B2 adducts are primary products which are supposed to be stereoisomers. This is the first report that proanthocyanidins can effectively scavenge reactive carbonyl species and thus inhibit the formation of AGEs. As proanthocyanidins behave in a similar fashion as aminoguanidine (AG), the first AGE inhibitor explored in clinical trials, they show great potential to be developed as agents to alleviate diabetic complications.     

A versatile method for assessing pathogenicity of Hymenoscyphus fraxineus to ash foliage

We describe a method for inoculating rachises of Fraxinus excelsior (European or common ash) with Hymenoscyphus fraxineus, which is faster than previous methods and allows associated foliar symptoms to be assessed on replicate leaves. A total of ten ash seedlings were inoculated with five isolates of H. fraxineus and lesion development assessed over four weeks. A five‐point disease progress scale of symptom development was developed from no lesion (0), lesion on rachis (1), “pre‐top dead,” with curling of distal leaflets and bending of the rachis (2), top dead, with wilting and death of distal leaflets (3) to leaf abscission (4). The method revealed variation in aggressiveness of H. fraxinus isolates and may be suitable for assessing the resistance of F. excelsior and other Fraxinus species to dieback. The in vitro growth rate of H. fraxineus isolates was highly correlated with both disease progress and the length of rachis lesions on susceptible plants, indicating that it can be used as a preliminary step in selecting isolates with high aggressiveness for use in resistance screening.     

Different in-planta and ex-planta activities of 7-chloro-4-(2-[trifluoromethyl]phenoxy)quinoline against Pyricularia grisea due to volatilization

7-Chloro-4-[2-(trifluoromethyl)phenoxy]quinoline (L Y248908) strongly inhibits mycelial growth of Pyricularia grisea in ex-planta assays but, when applied to the foliage of rice seedlings, its protective and curative properties against P. grisea are poor. The principal cause for this difference was found to be volatilization of LY248908 from treated foliage. Variations in fungal sensitivity (due to strain or development stage) and compound loss due to translocation, sequestration, metabolism, or degradation were shown not to be significant.     

Testing landscape metrics as indicators of habitat loss and fragmentation in continuous eucalypt forests (Queensland,Australia)

Landscape metrics are widely applied in landscape ecology to quantify landscape structure. However, many are poorly tested and require rigorous validation if they are to serve as reliable indicators of habitat loss and frag-mentation, such as Montreal Process Indicator 1.1e. We apply a landscape ecology theory, supported by explor-atory and confirmatory statistical techniques, to empirically test landscape metrics for reporting Montreal Process Indicator 1.1e in continuous dry eucalypt forests of sub-tropical Queensland, Australia. Target biota examined included: the Yellow-bellied Glider (Petaurus australis); the diversity of nectar and sap feeding glider species including P. australis, the Sugar Glider P. breviceps, the Squirrel Glider P. norfolcensis, and the Feathertail GliderAcrobates pygmaeus; six diurnal forest birds species; total diurnal bird species diversity; and the density of nec-tar-feeding diurnal bird species. Two scales of influence were considered: the stand-scale (2 ha), and a series of radial landscape extents (500 m –2 km;78–1250 ha) surrounding each fauna transect. For all biota, stand-scale structural and compositional attributes were found to be more influential than landscape metrics. For the Yellow-belliedGlider, the proportion of trace habitats with a residual element of old spotted-gum/ironbark eucalypt trees was a significant landscape metric at the 2 km landscape extent. This is a measure of habitat loss rather than habitat fragmentation. For the diversity of nectar and sap feeding glider species, the proportion of trace habitats with a high coefficient of variation in patch size at the 750 m extent was a significant landscape metric. None of the landscape metrics tested was important for diurnal forest birds. We conclude that no single landscape metricadequately captures the response of the regions forest biota per se. This poses a major challenge to regional reporting of Montreal Process Indicator 1.1e, fragmentation of forest types.This revised version was published online in May 2005 with corrections to the Cover Date.     

Imaging diagnosis: pneumothorax and focal peritonitis in a dog due to migration of an inhaled grass awn

A 1-year-old working Kelpie developed pneumothorax and focal peritonitis after inhalation of a grass awn that migrated from the lung, through the diaphragm, into the peritoneal cavity. Radiographic evidence of sternal lymph node enlargement was fundamental in the diagnosis of intraperitoneal disease and prompted abdominal ultrasound leading to definitive diagnosis.     

Phosphodiesterase isoenzymes in equine platelets and their influence on platelet adhesion

OBJECTIVE: To determine the phosphodiesterase (PDE) isoenzymes in equine platelets and evaluate their influence on platelet adhesion. SAMPLE POPULATION: Platelets obtained from healthy New Forest Pony geldings that ranged from 12 to 20 years of age (mean +/- SEM, 17.3 +/- 1.1 years). PROCEDURES: PDE isoenzyme activity in equine platelets was determined by use of a 2-step radioactive assay. Functional importance of PDE isoenzymes was established by use of selective inhibitors in a colorimetric adhesion assay. RESULTS: PDE1, PDE2, PDE3, and PDE5 and small amounts of PDE4 were found in equine platelets. Inhibition of PDE3 abolished platelet adhesion almost completely, whereas inhibition of PDE4 and PDE5 had little effect. CONCLUSIONS AND CLINICAL RELEVANCE: Function of equine platelets can be influenced by inhibition of PDE3. Selective PDE3 inhibitors may be clinically useful to regulate platelet function. They offer the advantage of increased potency with fewer adverse effects, compared with those for nonselective PDE inhibitors.     

Temperature and Salinity Tolerances of the Tropical Spiny Lobster,Panulirus ornatus

Interest in the development of aquaculture of the tropical spiny lobster, Panulirus ornatus, has increased markedly over the past 10 yr because of strong market demand and high prices. In Australia, economic conditions will necessitate that a semi‐intensive approach be taken, possibly involving managed environmental conditions. Identification of optimal temperature and salinity levels will be necessary, and therefore two experiments were performed to examine these two parameters. Juvenile lobsters were grown in tanks at five temperatures (19, 22, 25, 28 and 31 C). Growth was significantly affected by temperature (P < 0.01), and maximal growth occurred at 25–31 C. Examination of the temperature effect on molt increment and intermolt period indicated that 27 C was the optimal temperature, at which molt increment was greatest and intermolt period the least. Temperature also had a significant (P < 0.01) positive effect on apparent feed intake (AFI). Juvenile lobsters were also exposed to four different salinities (20, 25, 30 and 35 ppt) over a period of 91 d. Significant differences (P < 0.01) were apparent for both survival and growth. Lowest survival occurred at 35 ppt which may be attributable to higher cannibalism at that salinity. Growth was highest at 35 ppt and progressively less at lower salinities. Although full marine salinity (35 ppt) will generate best performance of P. ornatus, its capacity to tolerate reduced salinity will provide greater opportunity to develop commercial aquaculture.