Triiodothyronine accelerates the synthesis of Synapsin I in developing neurons from fetal rat brain cultured in a synthetic medium

The effect of Triiodothyronine (T3) on Synapsin I appearance in rat cortical neurons has been investigated in vitro. Neuronal cultures from 16-day-old fetal rat brain grown in the absence of T3, express immunohystochemically detectable Synapsin I at the 14th day in vitro. The addition of the hormone to the culture medium determines an early (at the 7th day in vitro) appearance of fluorescent dots specific for Synapsin I.     

The plant extracellular transglutaminase: what mammal analogues tell

The extracellular transglutaminases (TGs) in eukaryotes are responsible for the post-translational modification of proteins through different reactions, cross-linking being the best known. In higher plants, extracellular TG appears to be involved in roles similar to those performed by the mammalian counterparties. Since TGs are pleiotropic enzymes, to fully understand the role of plant enzymes it is possible to compare them with animal TGs, the most studied being TG of type 2 (TG2). The extracellular form of TG2 stabilizes the matrix and modulates the interaction of the integrin-fibronectin receptor, causing the adhesion of cells to the extracellular matrix; TG2 plays a role also in the pathogenicity. Extracellular TGs have also been identified in the cell wall of fungi, such as Candida and Saccharomyces, where they cross-link structural glycoproteins, and in Phytophthora, where they are involved in pathogenicity; in the alga Chlamydomonas, TGs link polyamines to glycoproteins thereby favouring the strengthening of cell wall. In higher plants, TG localized in the cell wall of flower petals appears to be involved in the structural reinforcement as well as senescence and cell death of the flower corolla. In the pollen cell wall an extracellular TG co-localizes with substrates and cross-linked products; it is required for the apical growth of pollen tubes. The pollen TG is also secreted into the extracellular matrix possibly allowing the migration of pollen tubes during fertilisation. Although pollen TGs seem to be secreted via vesicles transported along actin filaments, a different mechanism from the classical ER-Golgi pathway is possible, similar to TG2.     

Monitoring airborne genotoxicants in the rubber industry using genotoxicity tests and chemical analyses

This research was designed to examine the presence of mutagenic/carcinogenic compounds in airborne pollutants in the rubber industry using an integrated chemical/biological approach. Inhalable airborne particulate matter (PM-10: <10 μm) was collected in four rubber factories using a high-volume sampler equipped with a cascade impactor for particle fractionation. The organic extracts of two different fractions (0.5–10 μm and <0.5 μm) were examined for mutagenicity with the Ames test and for in vitro DNA-damaging activity in human leukocytes by single-cell microgel electrophoresis (Comet assay). The extracts were also studied by gas chromatography/mass spectrometry (GC/MS) for polycyclic aromatic hydrocarbon (PAH) content. Nitrosamines in ambient air were sampled on cartridges and analysed by GC with a thermal energy analyser (TEA) detector. Airborne volatile genotoxins were monitored in situ using a clastogenicity plant test (Tradescantia/micronuclei test). The results showed that airborne particulates were mainly very fine (<0.5 μm) and that trace amounts of genotoxic nitrosamines (N-nitrosodimethylamine: 0.10–0.98 μg/m³; N-nitrosomorpholine: 0.77–2.40 μg/m³) and PAH (total PAH: 0.34–11.35 μg/m³) were present in air samples. Some extracts, particularly those obtained from the finest fractions, were mutagenic with the Ames test and genotoxic with the Comet assay. In situ monitoring of volatile mutagens using the Tradescantia/micronuclei test gave positive results in two working environments. The results showed the applicability of this integrated chemical–biological approach for detecting volatile and non-volatile genotoxins and for monitoring genotoxic hazards in the rubber industry.     

Patterns of post-glacial spread and the extent of glacial refugia of European beech (Fagus sylvatica)

Aim  Establishing possible relationships between the magnitudes of the glacial distribution of the European beech, Fagus sylvatica L., and its post-glacial spread.
Location  Europe.
Methods  A database of over 400 pollen records has been used to locate Fagus populations at the end of the last glacial and during the post-glacial in Europe and to assess the areal extent of their past distribution.
Results  The rate of late-glacial and post-glacial increase in the number of pollen sites where Fagus was locally present conforms well to a logistic model of population growth. This suggests that the area occupied by beech populations expanded exponentially from the glacial refugia for a duration of over 10,000 years, until about 3500 yr bp . In the past three millennia beech populations increased at a slower rate, tending towards an equilibrium value.
Main conclusions  The conformity of the increase in beech distribution to the classical logistic model of population growth indicates that: (1) a multiplicative biological process was the main factor shaping the pattern of the post-glacial expansion of F. sylvatica in Europe, (2) climate conditions, human activity and competition may have influenced its rate of spread, and (3) beech populations did not expand with a moving closed front, but with a diffuse spread from scattered nuclei. The distribution of Fagus in Europe at the end of the last glacial appears to have been of two orders of magnitude less extensive than at present. Pleistocene refugia were likely to have been a mosaic of sparse stands of small populations scattered in multiple regions. Fagus populations appear to have increased very slowly and to a moderate extent in southern Europe, where they are now declining slightly. The central European populations increased quickly and extensively, reaching northern Europe, and are now approaching their carrying capacity.     

First record of Palisada maris-rubri (Ceramiales, Rhodophyta) from the Mediterranean Sea along with three proposed transfers to the genus Palisada

The first occurrence of Palisada maris-rubri (K.W. Nam et Saito) K.W. Nam (Ceramiales, Rhodomelaceae) from the Mediterranean Sea, is reported. To date the species was known only from tetrasporic specimens from the type locality (Ras Muhammed, Sinai, Egypt, Red Sea). Mediterranean thalli share nearly all vegetative and reproductive features with Red Sea specimens showing more robust thalli with axes to 3 mm broad and ultimate branchlets to 1000 µm broad, absence of intercellular spaces between medullary cells and epidermal cells in transverse section with a palisade arrangement. Male and cystocarpic thalli are recorded for the first time. Moreover, the analysis of characters of three species of Chondrophycus previously known from the Mediterranean Sea ( C. patentirameus (Montagne) K.W. Nam, C. tenerrimus (Cremades) G. Furnari et al. and C. thuyoides (Kützing) G. Furnari) led us to conclude that they belong to the genus Palisada . The following new combinations are formally proposed: P. patentiramea (Montagne) Serio et al., P. thuyoides (Kützing) Serio et al., P. tenerrima (Cremades) Serio et al.     

Auxin-like activity of 1,2-benzisothiazole derivatives

The 1,2-benzisothiazol-3-yl-acetic and -3-yl-butyric acids and their ethyl esters, amides and nitriles are generally active in the split pea stem test, induce an increase in both length and fresh weight of pea internodes, inhibit the development of pea roots, and, with some exceptions (1,2-benzisothiazol-3-yl-butyric amide and nitrile), induce the production of ethylene by pea segments. Moreover they stimulate cell multiplication and raise the degree of hydration of Helianthus tuberosus explants grown in vitro. These activities are often similar or sometimes higher than those of IAA. By contrast, the 1,2-benzisothiazole derivatives having a side chain with an odd number of carbon atoms (-3-yl-carboxylic and propionic acids, amides, ethyl esters and nitriles) are inactive or show a far lower activity.     

Enzyme inactivation and stabilization studies in an ultrafiltration reactor

Summary An ultrafiltration membrane enzymatic reactor is used in connection with different reacting systems.The experimental conditions are such that the enzyme, which operates at fairly high concentration levels because of the concentration polarization phenomena taking place in the reactor, is still in soluble form.The analysis of the system unsteady-state response enables the identification of the mechanism of enzyme deactivation and the extraction of the kinetic parameters of both the deactivation and the main reaction.The stabilizing effect observed in connection with enzyme entrapment within an inert gel deposited onto the U.F. membrane active surface is also discussed.List of Symbols A U.F. membrane cross sectional area cm² - C_E Enzyme concentration mg/ml - C_EI Enzyme concentration at the active membrane surface mg/ml - C_E Mean enzyme concentration mg/ml - c _s ^o Substrate concentration in the feed m moles/ml - c _s ^u Substrate concentration in the outlet m moles/ml - D_E Enzyme diffusivity cm²/s - Km michaelis constant mM - k₂ Kinetic constant of the enzymatic reaction m moles/mg s - k_d Kinetic constant of the enzyme deactivation reaction s^–1 - N^o Initial amount of active enzyme mg - N(t) Active enzyme amount at reaction time t mg - Q Flow rate ml/s - r Rate of the main reaction m moles/ml s - t Reaction time s - t^* Reaction time at which product concentration in the outlet is within ± 2% of the steady-state value s - v Fluid velocity cm/s - V Cell volume ml - V_B Volume within which 99% of the enzyme fed is contained at the steady-state ml - V_S Volume within which 99% of the total substrate concentration drop occurs at the steady-state ml - x Distance upstream the membrane measured from the membrane surface cm     

Conformational and functional properties of hemoglobin in water–organic cosolvent mixtures: Effect of ethylene glycol and glycerol on oxygen affinity

We report on the effects that the presence of ethylene glycol or glycerol has on the oxygen affinity of hemoglobin. We attribute these effects to an altered equilibrium between T and R quaternary conformations of hemoglobin and separate them into bulk-electrostatic and non-bulk-electrostatic contributions to the standard free-energy difference between the R and T states.