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1.
The present study was conducted to evaluate the effect of different salt concentrations (50 and 200 mM NaCl) on growth, permeability properties (electrolyte leakage, cell viability) and activity of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) in roots of maize seedlings. Both salt concentrations significantly affected growth and permeability properties of maize seedling roots and this negative effect increased with concentration of salt and duration of experiments. On the other hand salinity induced only small changes in the activities of GS and GDH, usually small increase in the activity was observed. To characterise the possible protective effect of silicon (Si) on maize roots exposed to saline stress, different concentrations of Si were simultaneously applied to both, low (50 mM) and high (200 mM) salt concentrations. Possible protective effects of Si on studied parameters were analysed in time range of 3 days treatment with the most positive effect on salt-induced root growth inhibition at high salt concentration and electrolyte leakage. The results show significant increase in GDH activity under all the tested conditions, although the mechanisms underlying this increase have not been elucidated. The results indicate that silicon may ameliorate the salt-induced root growth inhibition and increase the plant vigour at stressful conditions.  相似文献   
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Genetically transformed alfalfa (Medicago sativa L., cv. Zajearska 83) plantlets were obtained by inoculating somatic embryos with Agrobacterium tumefaciens strains A281/pGA472 and LBA4404/pBI121. Single somatic embryos, 5–7 mm long, were released from a repetitively embryogenic culture, wounded, and cocultivated with the bacteria. The agar-solidified culture medium contained mineral salts, vitamins, 40 g l–1 sucrose, 1 g l–1 yeast extract and 0.05 mg l–1 BA. Five clones, transformed with A281/pGA472, and 4 clones transformed with LBA4404/pBI121, were selected for proliferation by repetitive somatic embryogenesis, on media containing 100 mg l–1 of kanamycin. The transformation of kanamycin-resistant clones was confirmed by assaying the activity of neomycin phosphotransferase II and/or -glucuronidase enzymes, and by the Southern blot analysis. It is suggested that the transformation/regeneration system based on somatic embryogenesis may be suitable for establishing transgenic alfalfa lines. The relatively low frequency of embryo transformation is compensated for by abundant proliferation in secondary somatic embryogenesis.Abbreviations BA 6-benzyladenine - GUS -glucuronidase - Km kanamycin - NPTII neomycin phosphotransferase II - X-gluc 5-bromo-4-chloro-3-indolyl--glucuronic acid - BM basal medium  相似文献   
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Possibilities of adventitious buds induction on the cotyledons obtained from sterile seedlings ofAbies concolor xAbies grandis hybrid were investigated. The following variables influencing bud induction and their further development were studied: the effect of expiant age, the effect of different growth regulators and their concentrations and duration of their application. The most suitable expiants proved to be the cotyledons of 7 d old seedlings. The most efficient cytokinin was benzylaminopurine (S mg l?1) in combination with napthaleneacetic acid (0.01 mg l?1). The most optimal duration of treatment was 17 to 21 d culture of explants on induction medium. Shoot growth was achieved on basal medium to which 14 mg 1?1 spermidine was added.  相似文献   
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Summary The formation of 10 g polyols/L (glycerol, arabitol, xylitol) during L-lactic acid synthesis byRhizopus arrhizus was observed. Consumption of polyols after glucose exhaustion was discovered resulting in a subsequent rise in the lipid content of the mycelium. Lactate utilization was not detected.  相似文献   
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According to the common view, weak acid uncouplers increase proton conductance of biological (and phospholipid bilayer) membranes, thus effecting H+ fluxes driven by their electrochemical gradients. Under certain conditions, however, uncouplers can induce unexpected effects opposite to the dissipation of H+ gradients. Results are presented here demonstrating CCCP-induced proton influx into Saccharomyces cerevisiae cytosol driven by the electrochemical potentials of CCCP and its CCCP? anions, independent of electrochemical H+-gradient. Another view of week acid uncouplers’ action is proposed that is logically consistent with these observations.  相似文献   
8.
Based on light and scanning electron microscopical studies, a new nematode parasite, Lobocapillaria austropacifica n. sp. (Capillariidae), is described from the gall-bladder of the marine fish (obtuse barracuda) Sphyraena obtusata Cuvier (Perciformes: Sphyraenidae) from off the eastern Pacific coast of Australia, for which a new genus Lobocapillaria n. g. is established. This new genus is mainly characterised by a single row of stichocytes, the presence of two large, conspicuously elongated lateral caudal lobes and a pair of subventral papillae at their base in males, a flat spicule distended laterally towards its proximal end and provided with superficial rough transverse grooves, a spicular canal and a very long, aspinose spicular sheath with a conspicuous expansion near its proximal end when evaginated. Capillaria sphyraeni Parukhin, 1971 is transferred to Lobocapillaria as L. sphyreni (Parukhin, 1971) n. comb. A key to capillariid genera containing species parasitic in fishes is provided.  相似文献   
9.
The Drosophila salivary glands (SGs) were well known for the puffing patterns of their polytene chromosomes and so became a tissue of choice to study sequential gene activation by the steroid hormone ecdysone. One well‐documented function of these glands is to produce a secretory glue, which is released during pupariation to fix the freshly formed puparia to the substrate. Over the past two decades SGs have been used to address specific aspects of developmentally‐regulated programmed cell death (PCD) as it was thought that they are doomed for histolysis and after pupariation are just awaiting their fate. More recently, however, we have shown that for the first 3–4 h after pupariation SGs undergo tremendous endocytosis and vacuolation followed by vacuole neutralization and membrane consolidation. Furthermore, from 8 to 10 h after puparium formation (APF) SGs display massive apocrine secretion of a diverse set of cellular proteins. Here, we show that during the period from 11 to 12 h APF, the prepupal glands are very active in calcium oxalate (CaOx) extrusion that resembles renal or nephridial excretory activity. We provide genetic evidence that Prestin, a Drosophila homologue of the mammalian electrogenic anion exchange carrier SLC26A5, is responsible for the instantaneous production of CaOx by the late prepupal SGs. Its positive regulation by the protein kinases encoded by fray and wnk lead to increased production of CaOx. The formation of CaOx appears to be dependent on the cooperation between Prestin and the vATPase complex as treatment with bafilomycin A1 or concanamycin A abolishes the production of detectable CaOx. These data demonstrate that prepupal SGs remain fully viable, physiologically active and engaged in various cellular activities at least until early pupal period, that is, until moments prior to the execution of PCD.  相似文献   
10.
Infectious diseases and parasitism are major environmental forces decreasing fitness, and thus individual strategies aimed at preventing pathogen infections, either in an individual or their offspring, should be favoured by natural selection. The mineral fraction and some organic compounds in the shells of bird eggs are considered physical and chemical barriers against pathogen penetration to the embryo. However, eggshell pigment deposition has only recently been considered as a mechanism to resist pathogen penetration into the egg. By wiping the eggshell surface, the amount of pigment and some cuticle proteins were experimentally manipulated for the first time in nature. The effects on egg hatchability and offspring viability measured as nestling condition, immunocompetence and probability of recruitment were investigated in the common kestrel Falco tinnunculus. Protoporphyrin IX and biliverdin IXα to a lesser extent were the only identified pigments. The concentration of protoporphyrin IX and cuticle proteins were significantly reduced in the wiped with respect to the control treatment. Our study shows no evidence of a detrimental effect of the reduction of eggshell pigments on egg hatchability, mortality of the chicks during the nesting period, nestling body condition, nestling local immune response to PHA antigen or probability of recruitment. Further research will be necessary to elucidate the direct role of protoporphyrins and other pigments in egg bacterial infection.  相似文献   
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