Alnus

Alnus trees associate with ectomycorrhizal (ECM) fungi and nitrogen-fixing Frankia bacteria and, although their ECM fungal communities are uncommonly host specific and species poor, it is unclear whether the functioning of Alnus ECM fungal symbionts differs from that of other ECM hosts. We used exoenzyme root tip assays and molecular identification to test whether ECM fungi on Alnus rubra differed in their ability to access organic phosphorus (P) and nitrogen (N) when compared with ECM fungi on the non-Frankia host Pseudotsuga menziesii. At the community level, potential acid phosphatase (AP) activity of ECM fungal root tips from A. rubra was significantly higher than that from P. menziesii, whereas potential leucine aminopeptidase (LA) activity was significantly lower for A. rubra root tips at one of the two sites. At the individual species level, there was no clear relationship between ECM fungal relative root tip abundance and relative AP or LA enzyme activities on either host. O...

The aim of the study was to compare the airborne concentrations of allergenic pollen produced by three early flowering tree taxa (Corylus, Alnus, Betula) in the cities of Warsaw (central Poland), Lublin (eastern Poland) and Szczecin (western Poland) during the years 2000-2001. Measurements were performed by the volumetric method. Pollen seasons were defined as the periods in which 95% of the total catch occurred. The highest concentration and annual pollen count of Corylus was measured in Lublin in both seasons, while the highest annual pollen counts of Alnus and Betula were noted in Warsaw, where the annual pollen count of Betula in 2001 was four times higher than in 2000 and equalled 5,376 grains in m3 per 24 h. Significant differences in the pollen count of the examined taxa were observed between two seasons: the pollen count of Corylus was higher in 2000 than in 2001, while for Alnus and Betula the opposite was the case. The longest pollen seasons were observed at low annual pol...

Genetic admixture is supposed to be an important trigger of species expansions because it can create the potential for selection of genotypes suitable for new climatic conditions. Up until now, however, no continent-wide population genetic study has performed a detailed reconstruction of admixture events during natural species expansions. To fill this gap, we analysed the postglacial history of Alnus glutinosa, a keystone species of European swamp habitats, across its entire distribution range using two molecular markers, cpDNA and nuclear microsatellites. CpDNA revealed multiple southern refugia located in the Iberian, Apennine, Balkan and Anatolian Peninsulas, Corsica and North Africa. Analysis of microsatellites variation revealed three main directions of postglacial expansion: 1) from the northern part of the Iberian Peninsula to Western and Central Europe and subsequently to the British Isles, 2) from the Apennine Peninsula to the Alps, and 3) from the eastern part of the Balka...

Melatonin plays different physiological functions ranging from the regulation of circadian rhythms to tumor inhibition, owing to its antioxidant, immunomodulatory and anti-aging properties. Due to its pleiotropic functions, melatonin has been shown to elicit cytoprotective processes in normal cells and trigger pro-apoptotic signals in cancer cells. The therapeutic potential of melatonin analogues prompted us to investigate the in vitro and in vivo antitumor activity of new melatonin derivatives and explore the underlying molecular mechanisms. The experiments revealed that the new melatonin analogues inhibited the growth of melanoma and breast cancer cells in a dose- and time-dependent manner. In addition, our results indicated that melatonin derivative UCM 1037 could induce apoptosis in melanoma and breast cancer cells, as well as cell necrosis, in MCF-7. Together, apoptosis and necrosis could be two possible mechanisms to explain the cytotoxic effect of the melatonin analogue again...

The development and decline of alder floodplain forests and alder carrs along the Tyrrhenian coasts, in relation to sea level changes, geomorphological processes, human activity, and climate change are presented and discussed. A number of 22 pollen records, complemented by Alnus macrofossil data, document the presence of widespread alder populations in the coastal Tyrrhenian floodplains throughout the Holocene, although with different density from one site to the other, mostly depending on local hydrological conditions. The role of climate changes in the dynamics of floodplain forests appears uncertain. In the last two centuries, major reclamation works disrupted this natural vegetation to obtain fertile plains that are now exploited for agricultural purposes, industrial activities, urban areas and related infrastructures. Only a few remnants of the original alder forests are preserved by international conservation conventions, as biodiversity reservoirs of severely endangered habitats. However, the vanished alder forests, which proved to be able to rapidly recover several times through the Holocene, may still have some potential to be restored.

The name Alnus viridis (Chaix) DC., based on Betula viridis Chaix (1785), has traditionally been
attributed to green alders although it is based on a later basionym. Alnus alnobetula (Ehrh.) K. Koch
based on Betula alnobetula Ehrh. (1783) is the correct name for green alders. In light of the increasing
use and recognition of the name Alnus alnobetula (Ehrh.) K. Koch in the literature. I herein propose
new nomenclatural combinations to account for the Japanese and Chinese subspecies respectively:
Alnus alnobetula subsp. maximowiczii (Callier ex C.K. Schneid.) J. Chery and Alnus alnobetula subsp.
mandschurica (Callier ex C.K. Schneid.) J. Chery. Recent phylogenetic analyses place these two taxa in
the green alder species complex, suggesting that they should be treated as infraspecific taxa under the
polymorphic Alnus alnobetula.

The uptake of 226Ra from the contaminated soil was compared in three woody species: alder (Alnus glutinosa), birch (Betula pendula) and elder (Sambucus nigra). The 226Ra activities increased during the vegetation periods (in 2003, 2004 and 2005) both in the leaves and flowers+seeds. The highest accumulation was found in birch, reaching 0.41 Bq/g DW in the leaves (at the end of the vegetation period in 2003). The lowest 226Ra accumulation was determined in alder. The extent of 226Ra accumulation in the leaves of woody species demonstrates that these pioneer woody species can be used as remediation alternative to the use of herbs, provided that the removal of fallen leaves could be achieved in the end of vegetation period.

The nodule-forming actinobacterial genus Frankia can generally be divided into 4 taxonomic clusters, with clusters 1, 2, and 3 representing nitrogen-fixing strains of different host infection groups and cluster 4 representing atypical, generally non-nitrogen-fixing strains. Recently, quantitative PCR (qPCR)-based quantification methods have been developed for frankiae of clusters 1 and 3; however, similar approaches for clusters 2 and 4 were missing. We amended a database of partial 23S rRNA gene sequences of Frankia strains belonging to clusters 1 and 3 with sequences of frankiae representing clusters 2 and 4. The alignment allowed us to design primers and probes for the specific detection and quantification of these Frankia clusters by either Sybr Green- or TaqMan-based qPCR. Analyses of frankiae in different soils, all obtained from the same region in Illinois, USA, provided similar results, independent of the qPCR method applied, with abundance estimates of 10 × 10(5) to 15 × 10...

The objective of this study was to determine patterns of ectomycorrhizas (ECM) and arbuscular mycorrhizas (AM) colonization associated with Alnus acuminata (Andean alder), in relation to soil parameters (electrical conductivity, field H2O holding capacity, pH, available P, organic matter, and total N) at two different seasons (autumn and spring). The study was conducted in natural forests of A. acuminata situated