Short term effects of simulated acid mist on gas exchange of Eucalyptus globulus1

The effects of simulated acid mist treatment on net photosynthesis were determined on Eucalyptus globulus trees. Net assimilation decreased for all the three levels but after 3—4 days recovered only in the pH 3.5 one. Acidity effects are discussed in terms of morphological change to the leaves and as alteration of stomatal and mesophyll resistances. 1 Research work supported by C.N.R., Italy. Special grant I.P.R.A. sub-project 1. paper N. 2014     

Light-energy processing and freezing-tolerance traits in red spruce and black spruce: species and seed-source variation

Red spruce (Picea rubens Sarg.) and black spruce (Picea mariana (Mill.) B.S.P.) are genetically and morphologically similar but ecologically distinct species. We determined intraspecific seed-source and interspecific variation of red spruce and black spruce, from across the near-northern margins of their ranges, for several light-energy processing and freezing-tolerance adaptive traits. Before exposure to low temperature, red spruce had variable fluorescence (Fv) similar to black spruce, but higher photochemical efficiency (Fv/Fm), lower quantum yield, lower chlorophyll fluorescence (%), and higher thermal dissipation efficiency (qN), although the seed-source effect and the seed-source x species interaction were significant only for Fv/Fm. After low-temperature exposure (-40 degrees C), red spruce had significantly lower Fv/Fm, quantum yield and qN than black spruce, but higher chlorophyll fluorescence and relative fluorescence. Species, seed-source effect, and seed-source x species interaction were consistent with predictions based on genetic (e.g., geographic) origins. Multi-temperature exposures (5, -20 and -40 degrees C) often produced significant species and temperature effects, and species x temperature interactions as a result of species-specific responses to temperature exposures. The inherent physiological species-specific adaptations of red spruce and black spruce were largely consistent with a shade-tolerant, late-successional species and an early successional species, respectively. Species differences in physiological adaptations conform to a biological trade-off, probably as a result of natural selection pressure in response to light availability and prevailing temperature gradients.     

Aluminium chloride‐induced toxicity in zebrafish larvae

Embryos at shield stage and larvae at protruding mouth stage were exposed to different concentrations of aluminium chloride (AlCl₃) for 72 h with the purpose to analyse their phenotype and lethality. After 24, 48 and 72 h of treatment, higher toxicity of the metal was observed on larvae with minimal lethal concentration of 0.25, 0.20 and 0.08 mm , respectively, while for embryos the corresponding values were 40, 25 and 16 mm . We observed pericardial oedema and alteration of heart rate in 50% of larvae after 48 h of exposure to 100 μm . In larvae exposed to the same concentration, there was also a neurological injury at the level of glial cells, with the number of glial fibrillary acidic protein‐positive cells being significantly reduced. This study confirms the toxic nature of this metal and shows that aluminium could also interestingly represent a cardiotoxin in addition to its neurotoxic ability.     

Staining of heterochromatin bands and the determination of rye chromosomes in triticale (wheat × rye hybrid)

Summary Fifteen lines of triticale were studied using the C-banding staining method. A typical, complete chromosomal complement was found in 11 lines, while the remaining lines demonstrated some variations. A slight modification in the technique is discussed.Supported in part by CSRS/USDA Grant No. 801-15-03A.     

Antioxidant properties of sour cherries (Prunus cerasus L.): role of colorless phytochemicals from the methanolic extract of ripe fruits

Many edible plant metabolites are known to be useful as cellular antioxidants. In the search for antioxidative chemicals from native fruits of the Campania region of Italy, Prunus cerasus L., an acidic cherry widely used for culinary purposes, has been studied. Fruit crude extracts (MeOH, EtOAc, and hexane) were submitted to an antioxidative screening using specific assay media characterized from the presence of highly reactive radical species (DPPH*, ABTS*+, O2*-, NO) or lipoperoxidation markers. The reducing power of the samples was also determined. It was observed that the most polar extracts in MeOH and EtOAc were able to exercise a massive and dose-increasing antioxidative capacity. The peculiar efficacy of the same extracts was revealed by investigating their protein and deoxyribose oxidation capacity. A preliminary analysis of total phenol, flavonoid, and anthocyanin contents together with biological screening data put the basis on P. cerasus fruit phytochemical investigation of methanolic extract. Twenty secondary metabolites were isolated and characterized by spectroscopic (especially 1D and 2D NMR) and spectrometric techniques. 1-(4-Hydroxyphenyl)-1,2-ethanediol-1,2-bis-1-O-beta-D-glucopyranoside (3), (4-hydroxy-3-methoxyphenyl)methanol-1-O-beta-D-gentiobioside (4), epicatechin-3-malate (14), and epicatechin-3-(1'-methyl)malate (15) were isolated for the first time. All of the compounds were evaluated for their radical scavenging activity on DPPH*, O2*-, and NO. Flavonoids and quinic acid derivatives were found to be the more antioxidative substances.     

Evaluation of the Microalgae Paste Viability Produced in a Mollusk Hatchery in Southern Brazil

The present study was conducted to define a methodology to produce and store small‐scale microalgae paste to be used in a mollusk hatchery. Microalgae were cultured in 500 L fiberglass tanks, under temperature of 20 ± 2 C, Guillard f/2 culture medium, and continuous light intensity of 203–226 μmol photons/m²/sec. Cultures were centrifuged at 2000 g at the exponential growth phase. Microalgae cell quality after centrifugation and during storage was determined by analyses with Evan’s blue stain and by counting the number of total marine bacteria. Treatments with and without additive were applied to the microalgae paste produced, which was distributed into 100 mL plastic containers, capped, and stored under refrigeration at 4 ± 1 C. Results indicated that in the Chaetoceros muelleri paste, centrifugation did not damage the cells and the number of total marine bacteria reduced significantly from 2.9 × 10⁶ to 8.3 × 10⁵ colony‐forming units per milliliter. Chaetoceros muelleri and Chaetoceros calcitrans pastes stored with addition of 0.1% ascorbic acid had a shelf life shorter than 2 wk. For the treatment without additive, results with Evan’s blue stain showed that cells (99%) remained viable until the sixth week of storage for C. muelleri and seventh week of storage for Skeletonema sp. and C. calcitrans. The number of bacteria did not increase during storage for C. calcitrans and Skeletonema (P > 0.05). For C. muelleri, an increase in bacteria (P < 0.05) was observed after the sixth week of storage. This study demonstrated the feasibility to produce and store microalgae paste for a period of 2–8 wk, which allows it to be used as food source and also optimizes the use of microalgae cultured in laboratory.     

Biohybrid artificial pancreas: long-term implantation studies in diabetic, pancreatectomized dogs

Diabetic complications such as neuropathy, retinopathy, and renal and cardiovascular disease continue to pose major health risks for diabetic patients. Consequently, much effort has focused on approaches that could replace conventional insulin therapy and provide more precise regulation of blood glucose levels. The biohybrid perfused artificial pancreas was designed to incorporate islet tissue and a selectively permeable membrane that isolates this tissue from the immune system of the recipient. Biohybrid pancreas devices containing canine islet allografts were implanted in ten pancreatectomized dogs requiring 18 to 32 units of injected insulin daily. These implants resulted in good control of fasting glucose levels in six of these animals without further exogenous insulin for periods of up to 5 months.     

PAMELA measurements of cosmic-ray proton and helium spectra

Protons and helium nuclei are the most abundant components of the cosmic radiation. Precise measurements of their fluxes are needed to understand the acceleration and subsequent propagation of cosmic rays in our Galaxy. We report precision measurements of the proton and helium spectra in the rigidity range 1 gigavolt to 1.2 teravolts performed by the satellite-borne experiment PAMELA (payload for antimatter matter exploration and light-nuclei astrophysics). We find that the spectral shapes of these two species are different and cannot be described well by a single power law. These data challenge the current paradigm of cosmic-ray acceleration in supernova remnants followed by diffusive propagation in the Galaxy. More complex processes of acceleration and propagation of cosmic rays are required to explain the spectral structures observed in our data.     

Is the fragility of a liquid embedded in the properties of its glass?

When a liquid is cooled below its melting temperature, it usually crystallizes. However, if the quenching rate is fast enough, the system may remain in a disordered state, progressively losing its fluidity upon further cooling. When the time needed for the rearrangement of the local atomic structure reaches approximately 100 seconds, the system becomes "solid" for any practical purpose, and this defines the glass transition temperature Tg. Approaching this transition from the liquid side, different systems show qualitatively different temperature dependencies of the viscosity, and accordingly they have been classified by introducing the concept of "fragility." We report experimental observations that relate the microscopic properties of the glassy phase to the fragility. We find that the vibrational properties of the glass well below Tg are correlated with the fragility value. Consequently, we extend the fragility concept to the glassy state and indicate how to determine the fragility uniquely from glass properties well below Tg.     

Electronic transitions in perovskite: possible nonconvecting layers in the lower mantle

We measured the spin state of iron in magnesium silicate perovskite (Mg(0.9),Fe(0.1))SiO(3) at high pressure and found two electronic transitions occurring at 70 gigapascals and at 120 gigapascals, corresponding to partial and full electron pairing in iron, respectively. The proportion of iron in the low spin state thus grows with depth, increasing the transparency of the mantle in the infrared region, with a maximum at pressures consistent with the D" layer above the core-mantle boundary. The resulting increase in radiative thermal conductivity suggests the existence of nonconvecting layers in the lowermost mantle.