Characterisation of cyclodextrin glucanotransferase fromBacillus circulans ATCC 21783 in terms of cyclodextrin production

Cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) fromBacillus circulans ATCC 21783 was purified by ultrafiltration and a consecutive starch adsorption. Total enzyme yield of 75.5% and purification factor of 13.7 were achieved. CGTase was most active at 65°C, possessed two clearly revealed pH-optima at 6.0 and 8.6 and retained from 75 to 100% of its initial activity in a wide range of pH, between 5.0 and 11.0. The cyclising activity was enhanced by 1 mM CaCl₂ or 4 mM CoCl₂. The enzyme was thermostable up to 70°C, and 64% of the original activity remained at 70°C after 30 min heat treatment. Up to 41% conversion into cyclodextrins was obtained from 40 g l^?1 starch without using any additives. This CGTase produced two types of cyclodextrins, beta and gamma, in a ratio 73:27 after 4 h reaction time at 65°C. This feature of the enzyme could be of interest for industrial cyclodextrin production.     

Long-Term Treatment with Losartan Attenuates Seizure Activity and Neuronal Damage Without Affecting Behavioral Changes in a Model of Co-morbid Hypertension and Epilepsy

Over the last 10 years, accumulated experimental and clinical evidence has supported the idea that AT₁ receptor subtype is involved in epilepsy. Recently, we have shown that the selective AT₁ receptor antagonist losartan attenuates epileptogenesis and exerts neuroprotection in the CA1 area of the hippocampus in epileptic Wistar rats. This study aimed to verify the efficacy of long-term treatment with losartan (10 mg/kg) after kainate-induced status epilepticus (SE) on seizure activity, behavioral and biochemical changes, and neuronal damage in a model of co-morbid hypertension and epilepsy. Spontaneous seizures were video- and EEG-monitored in spontaneously hypertensive rats (SHRs) for a 16-week period after SE. The behavior was analyzed by open field, elevated plus maze, sugar preference test, and forced swim test. The levels of serotonin in the hippocampus and neuronal loss were estimated by HPLC and hematoxylin and eosin staining, respectively. The AT₁ receptor antagonism delayed the onset of seizures and alleviated their frequency and duration during and after discontinuation of treatment. Losartan showed neuroprotection mostly in the CA3 area of the hippocampus and the septo-temporal hilus of the dentate gyrus in SHRs. However, the AT₁ receptor antagonist did not exert a substantial influence on concomitant with epilepsy behavioral changes and decreased 5-HT levels in the hippocampus. Our results suggest that the antihypertensive therapy with an AT₁ receptor blocker might be effective against seizure activity and neuronal damage in a co-morbid hypertension and epilepsy.     

Comparative Characteristics of Growth and Photosynthesis of Sun and Shade Leaves from Normal and Pendulum Walnut (Juglans regia L.) Trees

Pendulum walnut leaves exhibited various adaptive responses related to the regulation of photon interception such as specific downward orientation, greater leaf area, and larger pigment pool. Changes in the regulation of PS2 such as higher thermal dissipation (NPQ) and lower quantum efficiency (Φ_PS2) that protect the photosynthetic apparatus against damages were also found. The growth and photosynthetic features of pendulum walnut leaf are interpreted as adaptations that allow the pendulum walnut tree to compensate the impaired ability by appropriate growth to ensure the energy needs for photosynthesis, respectively for biomass formation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Marine isolates of Trichoderma spp. as potential halotolerant agents of biological control for arid-zone agriculture

The scarcity of fresh water in the Mediterranean region necessitates the search for halotolerant agents of biological control of plant diseases that can be applied in arid-zone agriculture irrigated with saline water. Among 29 Trichoderma strains previously isolated from Mediterranean Psammocinia sp. sponges, the greatest number of isolates belong to the Trichoderma longibrachiatum-Hypocrea orientalis species pair (9), H. atroviridis/T. atroviride (9), and T. harzianum species complex (7), all of which are known for high mycoparasitic potential. In addition, one isolate of T. asperelloides and two putative new species, Trichoderma sp. O.Y. 14707 and O.Y. 2407, from Longibrachiatum and Strictipilosa clades, respectively, have been identified. In vitro salinity assays showed that the ability to tolerate increasing osmotic pressure (halotolerance) is a strain- or clade-specific property rather than a feature of a species. Only a few isolates were found to be sensitive to increased salinity, while others either were halotolerant or even demonstrated improved growth in increasingly saline conditions. In vitro antibiosis assays revealed strong antagonistic activity toward phytopathogens due to the production of both soluble and volatile metabolites. Two marine-derived Trichoderma isolates, identified as T. atroviride and T. asperelloides, respectively, effectively reduced Rhizoctonia solani damping-off disease on beans and also induced defense responses in cucumber seedlings against Pseudomonas syringae pv. lachrimans. This is the first inclusive evaluation of marine fungi as potential biocontrol agents.     

Natural history of SLC11 genes in vertebrates: tales from the fish world

Background  

The SLC11A1/Nramp1 and SLC11A2/Nramp2 genes belong to the SLC11/Nramp family of transmembrane divalent metal transporters, with SLC11A1 being associated with resistance to pathogens and SLC11A2 involved in intestinal iron uptake and transferrin-bound iron transport. Both members of the SLC11 gene family have been clearly identified in tetrapods; however SLC11A1 has never been documented in teleost fish and is believed to have been lost in this lineage during early vertebrate evolution. In the present work we characterized the SLC11 genes in teleosts and evaluated if the roles attributed to mammalian SLC11 genes are assured by other fish specific SLC11 gene members.     

Extracellular polymer substance synthesized by a halophilic bacterium Chromohalobacter canadensis 28

Applied Microbiology and Biotechnology - Halophilic microorganisms are producers of a lot of new compounds whose properties suggest promising perspectives for their biotechnological exploration....     

Growth and Endogenous Cytokinins of Juniper Shoots as Affected by High Metal Concentrations

The growth and the content of endogenous cytokinins (CKs) of current-year-old shoots from juniper plants (Juniperus communis L.) growing over and off ore site were compared. The juniper shoots from ore site (M plants) had higher metal content and exhibited delayed growth. Less bases and nucleosides of Z- and iP- type CK and more iP-conjugates were present in the M shoots. These changes were probably due to inhibited CK export from the roots and/or altered CK metabolism forming less biologically active CKs.     

Virion architecture unifies globally distributed pleolipoviruses infecting halophilic archaea

Our understanding of the third domain of life, Archaea, has greatly increased since its establishment some 20 years ago. The increasing information on archaea has also brought their viruses into the limelight. Today, about 100 archaeal viruses are known, which is a low number compared to the numbers of characterized bacterial or eukaryotic viruses. Here, we have performed a comparative biological and structural study of seven pleomorphic viruses infecting extremely halophilic archaea. The pleomorphic nature of this novel virion type was established by sedimentation analysis and cryo-electron microscopy. These nonlytic viruses form virions characterized by a lipid vesicle enclosing the genome, without any nucleoproteins. The viral lipids are unselectively acquired from host cell membranes. The virions contain two to three major structural proteins, which either are embedded in the membrane or form spikes distributed randomly on the external membrane surface. Thus, the most important step during virion assembly is most likely the interaction of the membrane proteins with the genome. The interaction can be driven by single-stranded or double-stranded DNA, resulting in the virions having similar architectures but different genome types. Based on our comparative study, these viruses probably form a novel group, which we define as pleolipoviruses.