Diurnal and seasonal variations in leaf hydraulic conductance in evergreen and deciduous trees

We studied changes in the hydraulic conductance of leaves (K(leaf)) between dawn and dusk during the growth period (July) and at midday at the beginning of autumn in four tree species. The main objectives of the study were to check the extent of diurnal and seasonal changes in K(leaf) and the relationships between K(leaf), irradiance and leaf gas exchange. Two evergreen (Aleurites moluccana and Persea americana) and two deciduous trees (Platanus orientalis and Quercus rubra) were studied. Leaf hydraulic conductance was measured every 2 h between 0700 and 1900 h in July and compared with values measured between 0900 and 1300 h in October. Other variables measured were photosynthetically active radiation (PAR), leaf conductance to water vapor (gL) and water potential (psiL). In July, K(leaf) varied by up to 75% in Pe. americana on a diurnal basis and by at least 44% in Q. rubra. The diurnal time course of K(leaf) showed a distinct increase between dawn and late morning (1100 h) and a subsequent decrease in the evening in A. moluccana and Pl. orientalis, whereas in the other two species, K(leaf) was highest just after dawn and lowest in the evening. In October, K(leaf) of all the species studied was lower than in July, with differences of 20 to 28% for A. moluccana and Pl. orientalis and of 66 to over 70% in Pe. americana and Q. rubra, respectively. Significant correlations were found between PAR and K(leaf) (in all species) as well as between gL and K(leaf) (in three out of four species). Leaf habit (evergreen or deciduous) did not influence absolute values of K(leaf) or its diurnal variation.     

Essential oils of commonly used plants as inhibitors of peroxynitrite-induced tyrosine nitration

The essential oils obtained from fifteen relevant and commonly used plants belonging to Cruciferae, Lamiaceae, Lauraceae, Apiaceae, and Zingiberaceae were screened using an in vitro model of peroxynitrite-induced tyrosine nitration. Almost complete inhibition of 3-nitrotyrosine formation (91% at 300 microg/ml) was achieved only with the essential oil obtained from the leaves of Laurus nobilis. 1,8-Cineol, accounting for a 50% of this essential oil, which resulted as inactive in this model, thus evidencing a major role for the minor volatile compounds present in the leaves.     

Comparison of methods used in European National Forest Inventories for the estimation of volume increment: towards harmonisation

Key message

The increment estimation methods of European NFIs were explored by means of 12 essential NFI features. The results indicate various differences among NFIs within the commonly acknowledged methodological frame. The perspectives for harmonisation at the European level are promising.

Context

The estimation of increment is implemented differently in European National Forest Inventories (NFIs) due to different historical origins of NFIs and sampling designs and field assessments accommodated to country-specific conditions. The aspired harmonisation of increment estimation requires a comparison and an analysis of NFI methods.

Aims

The objective was to investigate the differences in volume increment estimation methods used in European NFIs. The conducted work shall set a basis for harmonisation at the European level which is needed to improve information on forest resources for various strategic processes.

Methods

A comprehensive enquiry was conducted during Cost Action FP1001 to explore the methods of increment estimation of 29 European NFIs. The enquiry built upon the preceding Cost Action E43 and was complemented by an analysis of literature to demonstrate the methodological backgrounds.

Results

The comparison of methods revealed differences concerning the NFI features such as sampling grids, periodicity of assessments, permanent and temporary plots, use of remote sensing, sample tree selection, components of forest growth, forest area changes, sampling thresholds, field measurements, drain assessment, involved models and tree parts included in estimates.

Conclusion

Increment estimation methods differ considerably among European NFIs. Their harmonisation introduces new issues into the harmonisation process. Recent accomplishments and the increased use of sample-based inventories in Europe make perspectives for harmonised reporting of increment estimation promising.

     

Trichinella zimbabwensis in wild reptiles of Zimbabwe and Mozambique and farmed reptiles of Ethiopia

In 1995, a new species of Trichinella (Trichinella zimbabwensis) was discovered in farmed Nile crocodiles (Crocodylus niloticus) in Zimbabwe, where the mode of transmission was the consumption of the meat of slaughtered crocodiles, used as feed. To determine whether T. zimbabwensis affects poikilotherm vertebrates in the wild, monitor lizards (Varanus niloticus) and Nile crocodiles were collected in Zimbabwe and Mozambique. In 5 (17.6%) of the 28 monitor lizards from Zimbabwe, T. zimbabwensis larvae were identified. For the wild Nile crocodiles from Mozambique, species-level identification was not possible, yet immunohistochemical analysis revealed that 8 (20%) of the 40 animals harboured non-encapsulated Trichinella sp. larvae, which probably belonged to T. zimbabwensis. This is the first report of T. zimbabwensis in wild reptiles, and the findings are consistent with reports that vertebrates with scavenger and cannibalistic behaviour are the most important hosts of Trichinella spp. The wide distribution of monitor lizards and crocodiles in Africa and the development of national crocodile breeding programs in many African countries should be taken into consideration when evaluating the risk of transmission of this parasite to mammals, including humans.     

Evidence of fish and human pathogens associated with doctor fish (Garra rufa,Heckel, 1843) used for cosmetic treatment

Doctor fish (Garra rufa, Heckel, 1843) are increasingly used for cosmetic treatment raising particular concerns regarding the potential transmission of infections to clients. Investigations of microbial causes undertaken in two outbreaks of mortality among G. rufa used for cosmetic treatment revealed the presence of multiple bacteria, including both fish and human pathogens such as Aeromonas veronii, A. hydrophila, Vibrio cholerae, Shewanella putrefaciens, Mycobacterium marinum and M. goodii. This range of bacteria indicates an intense microbial proliferation involving multiple pathogens, most likely induced by the poor health condition of the fish. Most of the detected pathogens are well‐known agents of zoonosis. Indeed, M. goodii is an emerging nosocomial human pathogen that has never been detected in fish to date, nor in other animals. This first detection of M. goodii associated with fish infection points out a new zoonotic potential for this pathogen. These findings point out that handling, poor environmental conditions and the presence of fish pathogens, that can compromise the immune system of fish, can result in a mixed microbial proliferation and increase the spread of waterborne bacteria, including zoonosis agents. Accordingly, the microbiological surveillance of fish used for cosmetic treatment is extremely important, particularly in association with mortality outbreaks.     

Phylogenetic,genetic, and phenotypic diversity of Pseudomonas syringae pv. syringae strains isolated from citrus blast and black pit in Tunisia

Citrus blast and black pit caused by Pseudomonas syringae pv. syringae (Pss) is the only bacterial disease reported in Tunisian Citrus orchards. The phylogenetic relationship between Pss strains was studied based on multilocus sequence analysis (MLSA), using partial sequences of housekeeping genes rpoD, rpoB, gyrB, cts, and pfk for 14 representative Pss Citrus strains, including the reference strain LMG5496. The MLSA revealed that the studied Tunisian Citrus strains are closely related to LMG5496 and cluster in phylogroup 02. Based on the cts gene, the majority of Citrus strains clustered in clades “a” and “b”. However, five strains were placed in a newly defined clade “g”. We describe the presence of six different type III secreted effectors (T3SEs). These were found with frequencies of 100% for the effector hopAN1 and the helper hrpK1, 65% for hopT1-2, and 14% for hopN1, hopR1, and hopQ1-2. Investigation of copper resistance showed that 67% of our Pss Citrus strains from Tunisia are resistant to copper sulphate in vitro, and the copper resistance genes copABCDR were detected in 23% of the strains. Our results present new data concerning the genetic diversity and phylogeny, presence of T3SEs, and copper resistance within the Pss populations that affect Citrus in Tunisia.     

Determination of aloesin and aloeresin A for the detection of aloe in beverages

This work describes a sensitive high-performance liquid chromatography (HPLC) method for the quantification of aloesin and aloeresin A in alcoholic beverages containing aloe as a flavoring agent. The compounds were prepared from Aloe ferox juice. Sephadex LH20 and ion-exchange resin AG1X2 column chromatography were used for aloesin. Aloeresin A was obtained by Sephadex LH20 and silica gel column chromatography followed by purification on Discovery DSC-18 solid-phase extraction tubes. A 98 mg amount of aloesin (>99% purity) and 34 mg of aloeresin A (>98% purity) were recovered from 2.5 g of aloe juice. The HPLC method was validated, and intra- and interday performances were established. In-house validation was carried out by analyzing samples of beverages with and without aloe as a flavoring agent.     

Arbuscular mycorrhizal fungi of a Mediterranean island (Pianosa), within a UNESCO Biosphere Reserve

In this work we have determined the community composition of spore-forming arbuscular mycorrhizal fungi (AMF) in a maquis site on Pianosa island, a protected area within the Tuscan Islands UNESCO Biosphere Reserve, Italy. We have analysed rhizosphere soil of the dominant plant species Pistacia lentiscus, Smilax aspera, Rosmarinus officinalis and of the endemic plant Helichrysum litoreum. The AMF species recovered were: Scutellospora dipurpurescens, Glomus coronatum, Glomus mosseae, Glomus etunicatum, Glomus geosporum, Glomus viscosum, Entrophospora sp., Pacispora sp. and Glomus rubiforme. The identification of native S. dipurpurescens and G. coronatum was carried out on spores isolated from rhizosphere soil of H. litoreum, by combining morphological traits and 18S (SSU) and ITS rDNA sequences. Therefore, AMF species of Pianosa rhizosphere soils represent an important repository for the conservation and maintenance in their natural habitat of such beneficial symbionts, key microorganisms of soil fertility.