Leaf photosynthetic traits of 14 tropical rain forest species in relation to leaf nitrogen concentration and shade tolerance

Variability of leaf traits related to photosynthesis was assessed in seedlings from 14 tree species growing in the tropical rain forest of French Guiana. Leaf photosynthetic capacity (maximum rate of carboxylation and maximum rate of electron transport) was estimated by fitting a biochemical model of photosynthesis to response curves of net CO2 assimilation rate versus intercellular CO2 mole fraction. Leaf morphology described by leaf mass per unit leaf area (LMA), density and thickness, as well as area- and mass-based nitrogen (N) and carbon (C) concentrations, were recorded on the same leaves. Large interspecific variability was detected in photosynthetic capacity as well as in leaf structure and leaf N and C concentrations. No correlation was found between leaf thickness and density. The correlations between area- and mass-based leaf N concentration and photosynthetic capacity were poor. Conversely, the species differed greatly in relative N allocation to carboxylation and bioenergetics. Principal component analysis (PCA) revealed that, of the recorded traits, only the computed fraction of total leaf N invested in photosynthesis was tightly correlated to photosynthetic capacity. We also used PCA to test to what extent species with similar shade tolerances displayed converging leaf traits related to photosynthesis. No clear-cut ranking could be detected among the shade-tolerant groups, as confirmed by a one-way ANOVA. We conclude that the large interspecific diversity in photosynthetic capacity was mostly explained by differences in the relative allocation of N to photosynthesis and not by leaf N concentration, and that leaf traits related to photosynthetic capacity did not discriminate shade-tolerance ranking of these tropical tree species.     

Luminex-based triplex immunoassay for the simultaneous detection of soy, pea, and soluble wheat proteins in milk powder

An automated fluorescent microsphere-based flow cytometric triplex immunoassay, using the Luminex 100 flow analyzer with MultiAnalyte Profiling (xMAP) technology, was developed for the simultaneous detection of proteins from three vegetable sources as potential fraudulent adulterants in milk powder. In the final triplex inhibition immunoassay, soluble wheat proteins (SWP) and proteins from soy and pea were coupled to three different microsphere sets. A mixture of these microsphere sets was transferred to a microtiter plate well together with the sample and a mixture of three affinity-purified polyclonal antibodies raised against the proteins and labeled with a fluorophore (Alexa 532). After incubation for 1.5 h at room temperature in the dark, the fluorescence intensities on the microspheres were directly measured (no wash procedure) in the Luminex during 10 s per well (100 microspheres per set). The sensitivities of the three assays for plant protein extracts were determined as 0.5-0.6 microg/mL at 50% inhibition. For the detection of the vegetable proteins in milk powder, the samples were dissolved in buffer (0.1 g in 10 mL) and further diluted (20 times) to create a 50% inhibition at approximately 0.5% of the vegetable proteins in the total protein content of milk powder. With the help of calibration standards, prepared under conditions comparable to those for sample materials, the triplex immunoassay proved to be quantitative above 0.1%, although concentrations in high-heated milk powders were underestimated. Due to the xMAP technology, in which 100 different microsphere sets can be distinguished, this triplex immunoassay can easily be extended to detect other possible adulterants.     

Looks can deceive: Molecular identity of an intraerythrocytic apicomplexan parasite in Australian gliders

Two yellow-bellied gliders (Petaurus australis) had an intraerythrocytic parasite closely related to the cyst-forming coccidia (Apicomplexa: Sarcocystidae). The parasitaemia persisted for 3 months or more but was observed to clear within 3 years in captivity. The parasite appears not to significantly debilitate its infected host. Traditionally, using morphological identification, the intraerythrocytic parasite would have been classified within the Hepatozoon species typically found in red blood cells. However, molecular diagnostic techniques targeting the parasite's SSU rDNA and LSU rDNA demonstrated the unusual identity of this blood parasite and disputed its identity as a haemogregarine parasite of the genus Hepatozoon. The sequence was compared with available sequences from diverse mammalian and non-mammalian blood parasites (malaria, piroplasms, hemosporidia and sarcosporidia). The intraerythrocytic blood parasite was found to be most closely related to the cyst-forming coccidia including Besnoitia spp., Cystoisospora spp., Hammondia spp., Hyaloklossia lieberkuehni, Neospora caninum, Sarcocystis spp. and Toxoplasma gondii. The life cycle of this intraerythrocytic parasite remains unknown. The presented DNA identification demonstrates its suitability for an improved identification of blood parasites.     

Decline and likely extinction of a northern Australian native rodent, the Brush-tailed Rabbit-rat Conilurus penicillatus

Contemporary fire patterns are considered the most likely cause for regional population decline amongst small to medium mammals in northern tropical Australia. Here we assess the extinction risk faced by a vulnerable north Australian native rodent, the Brush-tailed Rabbit-rat Conilurus penicillatus in relation to fire frequency. This species has recently suffered a significant contraction in range. We provide the first quantitative evidence to demonstrate the immediate threat destructive wildfires and regular annual fire pose to the long-term population persistence of C. penicillatus. We show that late-dry season fires cause a reduction in both juvenile and adult survival probabilities. However, abundance declined at the unburnt as well as a frequently burnt site, suggesting that fire exclusion alone does not guarantee the species’ long-term persistence. Our model projections indicate that the remaining populations of C. penicillatus on the Northern Territory mainland risk extirpation within the next ten years. Conservation requires decisive management action to ameliorate extensive and destructive fires. A multi-faceted management plan needs to focus on restoring a fire management regime which generates a fine-scale mosaic of burnt and unburnt habitat, and the release of captive bred animals into fenced reserves free of exotic predators.     

Randomized controlled trial of the efficacy of cyclosporine in the treatment of atopic dermatitis in dogs

OBJECTIVE: To evaluate efficacy of cyclosporine A, administered at either of 2 dosages, in dogs with atopic dermatitis (AD). DESIGN: Multicenter randomized controlled trial. ANIMALS: 91 dogs with AD. PROCEDURE: Dogs were assigned to receive placebo (30 dogs), cyclosporine at a low dosage (2.5 mg/kg [1.1 mg/lb], PO, q 24 h for 6 weeks; 30 dogs), or cyclosporine at a high dosage (5.0 mg/kg [2.3 mg/lb], PO, q 24 h for 6 weeks; 31 dogs). RESULTS: After 6 weeks, mean percentage reductions, compared with baseline scores, in scores of lesion severity were 34, 41, and 67% for dogs treated with the placebo, cyclosporine at the low dosage, and cyclosporine at the high dosage, respectively. Similarly, mean percentage reductions in pruritus scores were 15, 31, and 45%, respectively. Percentage reductions in skin lesion and pruritus scores were significantly higher for dogs given cyclosporine at the high dosage than for dogs given the placebo. Treatment efficacy was significantly associated with whether dogs had a history of seasonal AD. Percentage reductions in skin lesion and pruritus scores were high for dogs treated with cyclosporine at the highest dosage that had a history of nonseasonal AD. Dogs in all groups with seasonal AD improved during the study period. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that oral administration of cyclosporine at a dosage of 5.0 mg/kg once daily is effective in reducing severity of pruritus and skin lesions in dogs with AD, especially those with nonseasonal disease.     

Analysis and management of resistance to chemotherapeutants in salmon lice,Lepeophtheirus salmonis (Copepoda: Caligidae)

In Northern Europe and Canada, the salmon louse, Lepeophtheirus salmonis (Kr?yer), seriously affects the marine phase of salmon production. Although the problem is long-standing, the development of sustainable methods of pest management has been unable to keep pace with the intensification of production, leading to large-scale reliance on very few chemotherapeutants. This runs the risk of selecting for genetically determined resistance in target organisms. There are many examples of similar evolutionary adaptations in arthropod pests of arable crops, livestock and human health. Several hundred pest species are now documented as being resistant to one or more chemical classes of insecticides and acaricides. Many of these compounds are identical or closely related to ones currently employed against salmon lice. It is, therefore, opportune to consider what lessons have been learnt from contending with resistance in terrestrial organisms, the implications for sustainable use of chemotherapeutants in aquaculture, and the potential for developing effective resistance management strategies. An EU-funded project named SEARCH (QLK2-CT-2000-00809) has been initiated to explore in more detail the diagnosis, incidence, dynamics and management of resistance to chemotherapeutants in L salmonis.     

The stock structure of grey mackerel Scomberomorus semifasciatus in Australia as inferred from its parasite fauna

The scombrid Scomberomorus semifasciatus is an important component of inshore fisheries in tropical Australia. Data on the parasite fauna of 593 fish from areas off northern and eastern Australia were examined for evidence of discrete fish populations. The parasites used were juveniles of Pterobothrium pearsoni, Callitetrarhynchus gracilis, Anisakis simplex (sensu latu) and Terranova sp. Tukey Kramer pairwise comparisons gave significant differences in the abundances of two or more parasites between fish from the east coast, the eastern Gulf of Carpentaria and the remainder of northern Australia. Multivariate analysis gave further evidence of differences and the results suggest that at least 4 populations or stocks of grey mackerel occur along the northern and eastern coastline of Australia.     

Post-genomics of microsporidia, with emphasis on a model of minimal eukaryotic proteome: a review

The genome sequence of the microsporidian parasite Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 contains about 2,000 genes that are representative of a non-redundant potential proteome composed of 1,909 protein chains. The purpose of this review is to relate some advances in the characterisation of this proteome through bioinformatics and experimental approaches. The reduced diversity of the set of E. cuniculi proteins is perceptible in all the compilations of predicted domains, orthologs, families and superfamilies, available in several public databases. The phyletic patterns of orthologs for seven eukaryotic organisms support an extensive gene loss in the fungal clade, with additional deletions in E. cuniculi. Most microsporidial orthologs are the smallest ones among eukaryotes, justifying an interest in the use of these compacted proteins to better discriminate between essential and non-essential regions. The three components of the E. cuniculi mRNA capping apparatus have been especially well characterized and the three-dimensional structure of the cap methyltransferase has been elucidated following the crystallisation of the microsporidial enzyme Ecm1. So far, our mass spectrometry-based analyses of the E. cuniculi spore proteome has led to the identification of about 170 proteins, one-quarter of these having no clearly predicted function. Immunocytochemical studies are in progress to determine the subcellular localisation of microsporidia-specific proteins. Post-translational modifications such as phosphorylation and glycosylation are expected to be soon explored.     

Assessment of cocoa input needs using soil types and soil spectral analysis

In this study, diffuse reflectance spectroscopy (DRS) approach was examined for making input recommendations in the smallholder cocoa farms of Papua New Guinea (PNG). Soil samples were collected from four provinces of PNG. Soil samples from four different depths (0–10, 10–30, 30–60 and 60–90 cm) of 32 profiles in each of these site were used to create a database of soil chemical and physical properties. Spectral reflectance values at 1 nm interval covering visible to shortwave‐infrared (350–2,500 nm) were collected for each of these soil samples to develop partial least squares regression models. Soil textural fractions, soil organic carbon contents and available N were well predicted by the DRS approach with R² values larger than 0.75. Moderate to poor estimation efficiencies were observed for remaining parameters. Nevertheless, the estimated soil attributes and their corresponding measured soil parameters were used as inputs to an input recommendation model of soil diagnosis to create input recommendation for a targeted cocoa yield of 1,000 kg dry cocoa beans ha^‐1 Resulting input recommendations were similar for both of these input sources (measured and DRS‐estimated) suggesting that the DRS approach may provide an easy way to create input recommendations.