X-ray microdensitometry applied to subfossil tree-rings: growth characteristics of ancient pines from the southern boreal forest zone in Finland at intra-annual to centennial time-scales

A collection of subfossil wood of Pinus sylvestris (Scots pine) was exposed to X-ray densitometry. The collection of 64 samples from the southern boreal forest zone was dendrochronologically cross-dated to a.d. 673-1788. Growth characteristics were determined by performing density profiles including the following parameters: minimum density, earlywood and latewood boundary density, maximum density, earlywood width, earlywood density, latewood width, latewood density, annual ring width and annual ring density. Seven out of the nine parameters were found to contain non-climatic growth trends and six were found to be heteroscedastic in their variance. Tree-specific records were indexed, to remove the non-climatic growth trends and stabilize the variance, and combined into nine parameter-specific tree-ring chronologies. Growth characteristics of the pines changed in parallel with the generally agreed climatic cooling from the Medieval Warm Period to the Little Ice Age: pine tree-rings showed decreasing maximum densities from the period a.d. 975-1150 to a.d. 1450–1625. A concomitant change in the intra-annual growth characteristics was detected between these periods. The findings indicate that not only the trees growing near the species’ distributional limits are sensitive to large-scale climatic variations but also the trees growing in habitats remote from the timberline have noticeably responded to past climate changes.     

A simple non-invasive protocol to establish primary cell lines from tail and toe explants for cytogenetic studies in Australian dragon lizards (Squamata: Agamidae)

Primary cell lines were established from cultures of tail and toe clips of five species of Australian dragon lizards: Tympanocryptis pinguicolla, Tympanocryptis sp., Ctenophorus fordi, Amphibolurus norrisi and Pogona vitticeps. The start of exponential cell growth ranged from 1 to 5 weeks. Cultures from all specimens had fibroblastic morphology. Cell lines were propagated continuously up to ten passages, cryopreserved and recovered successfully. We found no reduction in cell viability after short term (<6 months) storage at −80 °C. Mitotic metaphase chromosomes were harvested from these cell lines and used in differential staining, banding and fluorescent in situ hybridisation. Cell lines maintained normal diploidy in all species. This study reports a simple non-invasive method for establishing primary cell lines from Australian dragon lizards without sacrifice. The method is likely to be applicable to a range of species. Such cell lines provide a virtually unlimited source of material for cytogenetic, evolutionary and genomic studies.     

Plant Conservation in the Caribbean Island Biodiversity Hotspot

While the Caribbean is a recognized “biodiversity hotspot”, plant conservation has not received adequate attention; particularly, given the high levels of endemism in many plant groups. Besides establishing protected areas, there needs to be a sustained effort to study the taxonomy, systematics and ecology of the flora. Recent phylogenetic studies have shown high levels of endemism and conservation studies indicate a large propotion of the flora is threatened with extinction. Eight recommendations are given for plant conservation in the region.     

Allelopathic impact of artificially applied coumarin on <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f.sp. <Emphasis Type="Italic">niveum</Emphasis>

Watermelon production is threatened by fusarium wilt caused by Fusarium oxysporum f.sp. niveum (FON) in continuous cultivation system. Some elements, mainly allelochemicals, released from living roots or decayed plants might be associated with the disease. The purpose of this work was to evaluate the possible impact of coumarin, one kind of watermelon allelochemical, on FON. Furthermore, possible new mechanisms might be investigated during the ecological interactions of plant-microbe. Results showed that coumarin strongly inhibited growth of FON leading to a decrease in its biomass, dry weight of mycelia of FON in a liquid culture. The dry weight was decreased by 62.9% compared with control. The hyphal growth of FON on plates was stopped at high (>400 mg l⁻¹) concentrations of coumarin. At 320 mg l⁻¹, sporulation and enzyme activities of FON were also severely suppressed by coumarin. The yield of conidia, and the activities of proteinase, cellulase, and amylase were reduced by 98.9%, 79.7%, 29.8% and 15.9% respectively. However, conidial germination and mycotoxin (MT) production of FON were greatly stimulated, being increased by 55.7% and 14.9 fold at 320 mg l⁻¹ respectively. We conclude that coumarin acted as an allelochemical substance to inhibit growth and pathogenic enzyme activities of FON but to stimulate mycotoxin production and conidial germination. It was suggested that coumarin acted as a signal transduction element bridging plant and pathogen in the process of plant-microbe interactions.     

Growth Factors and Steroid Mediated Regulation of Cytoskeletal Protein Expression in Serum-Deprived Primary Astrocyte Cultures

In this research we aimed to investigate the interactions between growth factors (GFs) and dexamethasone (DEX) on cytoskeletal proteins GFAP and vimentin (VIM) expression under different experimental conditions. Condition I: 24 h pretreatment with bFGF, subsequent 72 h switching in serum-free medium (SFM) and final addition of GFs, alone or by two in the last 24 h, after a prolonged (60 h) DEX treatment. Condition II: 36 h pretreatment with DEX (with bFGF in the last 24 h), followed by SFM for 60 h and final addition for 24 h with growth factors alone or two of them togheter. Western blot analysis data showed a marked GFAP expression in cultures submitted to Condition I comparing results to untreated or treated controls. VIM expression was instead significantly reduced after GFs addition in the last 24 h of 60 h DEX treatment, respect to control DEX-pretreated ones. Referring data to untreated controls, VIM expression was significantly enhanced after GFs addition. GFAP showed also a significant increase in astrocytes submitted to Condition II, respect to untreated or treated control cultures. VIM expression was up and down regulated under Condition II. Collectively, our findings evidence an interactive dialogue between GFs and DEX in astroglial cultures, co-pretreated with DEX and bFGF, regulating cytoskeletal network under stressfull conditions. Special issue article in honor of Dr. Anna Maria Giuffrida-Stella.     

Magnesium Supplementation did not Affect the Increasing Bone Zinc Concentration in Rats Given Excess Calcium as Carbonate

We investigated the effect of magnesium supplementation on zinc distribution in rats given excess calcium as carbonate. Rats were given a control diet (5 g/kg calcium and 0.5 g/kg magnesium), a high calcium diet (HC, 25 g/kg calcium and 0.5 g/kg magnesium) or the high calcium diet supplied with magnesium (HCM, 25 g/kg calcium and 2.5 g/kg magnesium) for 4 weeks. Calcium carbonate and magnesium oxide were used for increasing these mineral concentrations in diets. Although feed intake did not differ among the groups, the excess calcium suppressed feed efficiency, irrespective of dietary magnesium concentration. Femoral magnesium concentration was lower in the HC group than in the control and the HCM groups. Femoral zinc concentration was higher in the HC group and the HCM group than in the control group. The zinc concentration in the kidney was lower in the HC group and the HCM group than in the control group. The excess calcium did not affect zinc concentration in plasma and other tissues such as the liver, testis, and spleen, irrespective of dietary magnesium. These results suggest that the increasing bone zinc and the decreasing renal zinc do not result from magnesium insufficiency in rats given excess calcium as carbonate.     

Selected airborne allergenic fungal spores and meteorological factors in Szczecin,Poland, 2004–2006

Airborne fungal spore concentrations in Szczecin, Poland, were studied between 2004 and 2006 with the objective of determining a seasonal variation in the concentrations of selected fungal spore types in relation to meteorological parameters. The presence of spores of five taxa, namely, Cladosporium, Ganoderma, Alternaria, Leptosphaeria and Didymella, was recorded using a volumetric method (Hirst type). Fungal spores were present in the air in large numbers during the summer, with the highest concentrations recorded mainly in June, July and August. The peak concentrations of two of the studied spore types, Ganoderma and Alternaria, occurred in August, while the concentrations of Cladosporium, Leptosphaeria and Didymella spores were the highest in July. Multiple regression analysis was performed for three fungal seasons—2004, 2005 and 2006. Spore concentration was found to be positively correlated with the minimum temperature. For some spore types, there was also a significant correlation between concentrations, relative humidity and rain.     

Short-term variation of nutritive and metabolic parameters in <Emphasis Type="Italic">Temora longicornis</Emphasis> females (Crustacea,Copepoda) as a response to diet shift and starvation

Changes in fatty acid patterns, digestive and metabolic enzyme activities and egg production rates (EPR) were studied in the small calanoid copepod Temora longicornis. Female copepods were collected in spring 2005 off Helgoland (North Sea). In the laboratory one group of copepods was fed with the cryptophycean Rhodomonas baltica for a period of 3 days. Another group of copepods was maintained without food. According to the fatty acid patterns, animals from the field were feeding on a more detrital, animal-based and to a minor extent to a diatom-based diet. Under laboratory conditions, females rapidly accumulated fatty acids such as 18:4 (n-3), 18:3 (n-3) and 18:2 (n-6) which are specific of R. baltica. Diatom-specific fatty acids such as 16:1 (n-7) were strongly reduced. In fed animals the activities of digestive and metabolic enzymes remained constant and egg production rates were highest on day 2. Starving animals, in contrast, showed significantly reduced faecal pellet production and EPR. Proteolytic enzyme activity decreased rapidly within 24 h and remained at a low level until the end of the experiment. Citrate synthase decreased continuously as well. T. longicornis rapidly reacts to dietary changes and food depletion. It has limited energy stores and, thus, strongly depends on continuous food supply.     

Modeling the spontaneous initiation of the polymerization of methyl methacrylate

The mechanism of the spontaneous initiation of the polymerization of methyl methacrylate (MMA) was investigated theoretically. The six minimum energy paths (MEP) of the possible reactions were calculated using the density functional theory (DFT) in conjunction with the B3LYP functional and 6-31G* basis set. The Diels-Alder initiation mechanism (path (I) and path (II)) with remarkably high energy barriers is not applicable to MMA. Four favorable paths were found (path (III), path (IV), path (V) and path (VI)), which are supporting the Flory mechanism. Path (V) has the lowest active energy. Therefore this path is considered as the main path for the spontaneous polymerization of MMA. Figure The mechanism of the spontaneous initiation of the polymerization of methyl methacrylate (MMA) was investigated theoretically. The six minimum energy paths (MEP) of the possible reactions were calculated using the density functional theory (DFT) in conjunction with the B3LYP functional and 6-31G* basis set.