Antibiotic resistance in Nicotiana.

The mode of action, and mechanism of resistance of many antibiotics are known since antibiotic resistance markers are commonly used in microbial genetics. Some of them, such as streptomycin, kanamycin and chloramphenicol selectively inhibit protein synthesis on the ''bacterial type'' ribosomes of the chloroplasts and mitochondria. Resistance to these antibiotics is, in some cases, coded by the organellar DNA, so these mutations are convenient markers in studies on organelle segregation, recombination and function in fungi and a 1 gae 1 The need for marker mutations in plant cell genetics, and our interest in cytoplasmic organelles, suggested to us the selection of antibiotic resistant cell lines in cell cultures of two species belonging to the genus Nicotiana~ N. tabacum and N. sylvestris. Streptomycin, kanamycin and chloramphenicol resistant lines described in flowering plants (N. tabacum~ N. sylvestris~ Petunia hybrida) and the moss, Physcomitrella patens~ have been reviewed. In the next sections some recent results on streptomycin, chloramphenicol and kanamycin resistance from our laboratory will follow

Antibiotic resistance in Nicotiana.

The mode of action, and mechanism of resistance of many antibiotics are known since antibiotic resistance markers are commonly used in microbial genetics. Some of them, such as streptomycin, kanamycin and chloramphenicol selectively inhibit protein synthesis on the ''bacterial type'' ribosomes of the chloroplasts and mitochondria. Resistance to these antibiotics is, in some cases, coded by the organellar DNA, so these mutations are convenient markers in studies on organelle segregation, recombination and function in fungi and a 1 gae 1 The need for marker mutations in plant cell genetics, and our interest in cytoplasmic organelles, suggested to us the selection of antibiotic resistant cell lines in cell cultures of two species belonging to the genus Nicotiana~ N. tabacum and N. sylvestris. Streptomycin, kanamycin and chloramphenicol resistant lines described in flowering plants (N. tabacum~ N. sylvestris~ Petunia hybrida) and the moss, Physcomitrella patens~ have been reviewed. In the next sections some recent results on streptomycin, chloramphenicol and kanamycin resistance from our laboratory will follow

The Beta-1-Receptor Blocker Nebivolol Elicits Dilation of Cerebral Arteries by Reducing Smooth Muscle [Ca2+]i

RATIONALE: Nebivolol is known to have beta-1 blocker activity, but it was also suggested that it elicits relaxation of the peripheral arteries in part via release of nitric oxide (NO). However, the effect of nebivolol on the vasomotor tone of cerebral arteries is still unclear. OBJECTIVE: To assess the effects of nebivolol on the diameter of isolated rat basilar arteries (BA) in control, in the presence of inhibitors of vasomotor signaling pathways of know action and hemolysed blood. METHODS AND RESULTS: Vasomotor responses were measured by videomicroscopy and the intracellular Ca2+ by the Fura-2 AM ratiometric method. Under control conditions, nebivolol elicited a substantial dilation of the BA (from 216±22 to 394±20 μm; p CONCLUSIONS: Nebivolol seems to have an important dilator effect in cerebral arteries, which is mediated via several vasomotor mechanisms, converging on the reduction of smooth muscle Ca2+ levels. As such, nebivolol may be effective to improve cerebral circulation in various diseased conditions, such as hemorrhage

Impact of the stringency of cell selection on plastid segregation in protoplast fusion-derived Nicotiana regenerates.

Vegetative segregation of a mixed plastid population in protoplast fusion-derived cell lines can be directed by a selection favouring the multiplication of one of the parental plastid types. This report defines some of the critical conditions leading to a homogeneous plastid population in cybrid plants generated by protoplast fusion between Nicotiana plumbaginifolia and an albino and streptomycin-resistant N. tabacum plastid mutant. Light (1,500 Ix) conferred a strong selective advantage to chloroplasts versus albino plastids, while the lack of this effect in dim light (300 Ix) indicated that a sufficient light intensity is essential to the phenomenon. Selection on streptomycin-containing medium in the dark, however, led to the preferential multiplication of resistant plastids. Streptomycin selection of resistant chloroplasts in the light, consequently, results in a plastid selection of doubled stringency. In another experiment a definite, but leaky, selection for chloroplast recombination (selection for greening on streptomycin-containing medium in dim light) was used to reveal various recombination products. Protoplast fusion in fact resulted in cybrid plants showing only simple chimeric segregation of unchanged parental plastids. These results demonstrate the essential requirement for stringent plastid selection, as defined by cell culture conditions, to precede the formation of shoots expected to possess the desired plastid genetic composition

Impact of the stringency of cell selection on plastid segregation in protoplast fusion-derived Nicotiana regenerates.

Vegetative segregation of a mixed plastid population in protoplast fusion-derived cell lines can be directed by a selection favouring the multiplication of one of the parental plastid types. This report defines some of the critical conditions leading to a homogeneous plastid population in cybrid plants generated by protoplast fusion between Nicotiana plumbaginifolia and an albino and streptomycin-resistant N. tabacum plastid mutant. Light (1,500 Ix) conferred a strong selective advantage to chloroplasts versus albino plastids, while the lack of this effect in dim light (300 Ix) indicated that a sufficient light intensity is essential to the phenomenon. Selection on streptomycin-containing medium in the dark, however, led to the preferential multiplication of resistant plastids. Streptomycin selection of resistant chloroplasts in the light, consequently, results in a plastid selection of doubled stringency. In another experiment a definite, but leaky, selection for chloroplast recombination (selection for greening on streptomycin-containing medium in dim light) was used to reveal various recombination products. Protoplast fusion in fact resulted in cybrid plants showing only simple chimeric segregation of unchanged parental plastids. These results demonstrate the essential requirement for stringent plastid selection, as defined by cell culture conditions, to precede the formation of shoots expected to possess the desired plastid genetic composition

Plants in Microgravity: Molecular and Technological Perspectives

Plants are vital components of our ecosystem for a balanced life here on Earth, as a source of both food and oxygen for survival. Recent space exploration has extended the field of plant biology, allowing for future studies on life support farming on distant planets. This exploration will utilize life support technologies for long-term human space flights and settlements. Such longer space missions will depend on the supply of clean air, food, and proper waste management. The ubiquitous force of gravity is known to impact plant growth and development. Despite this, we still have limited knowledge about how plants can sense and adapt to microgravity in space. Thus, the ability of plants to survive in microgravity in space settings becomes an intriguing topic to be investigated in detail. The new knowledge could be applied to provide food for astronaut missions to space and could also teach us more about how plants can adapt to unique environments. Here, we briefly review and discuss the current knowledge about plant gravity-sensing mechanisms and the experimental possibilities to research microgravity-effects on plants either on the Earth or in orbit

Abiotic stress response of near-isogenic spring durum wheat lines under different sowing densities

A detailed study was made of changes in the plant development, morphology, physiology and yield biology of near-isogenic lines of spring durum wheat sown in the field with different plant densities in two consecutive years (2013–2014). An analysis was made of the drought tolerance of isogenic lines selected for yield QTLs (QYld.idw-2B and QYld.idw-3B), and the presence of QTL effects was examined in spring sowings. Comparisons were made of the traits of the isogenic pairs QYld.idw-3B++ and QYld.idw-3B−− both within and between the pairs. Changes in the polyamine content, antioxidant enzyme activity, chlorophyll content of the flag leaf and the normalized difference vegetation index (NDVI) of the plot were monitored in response to drought stress, and the relationship between these components and the yield was analyzed. In the case of moderate stress, differences between the NIL++ and NIL−− pairs appeared in the early dough stage, indicating that the QYld.idw-3B++ QTL region was able to maintain photosynthetic activity for a longer period, resulting in greater grain number and grain weight at the end of the growing period. The chlorophyll content of the flag leaf in phenophases Z77 and Z83 was significantly correlated with the grain number and grain weight of the main spike. The grain yield was greatly influenced by the treatment, while the genotype had a significant effect on the thousand-kernel weight and on the grain number and grain weight of the main spike. When the lines were compared in the non-irrigated treatment, significantly more grains and significantly higher grain weight were observed in the main spike in NIL++ lines, confirming the theory that the higher yields of the QYld.idw-3B++ lines when sown in spring and exposed to drought stress could be attributed to the positive effect of the “Kofa” QTL on chromosome 3B

From Newborn to Senescence Morphological and Functional Remodeling Leads to Increased Contractile Capacity of Arteries

Aging induces substantial morphological and functional changes in vessels. We hypothesized that due to morphological remodeling the total contractile forces of arteries increase, especially in older age as a function of age. Mean arterial blood pressure of rats and morphological and functional characteristics of isolated carotid arteries rats, from newborn to senescent, were assessed. The arterial blood pressure of rats increased significantly from 0.25 to the age of 6 months, and then it reached a level, which was maintained until age of 30 months. Wall lumen and wall thickness increased with age, mostly due to media (smooth muscle) thickening, whereas wall tension gradually reduced with age. Contractions of arteries to nonreceptor-mediated vasomotor agent (KCl, 60mM) increased in three consecutive age groups, whereas contractility first increased (until 2 months), then it did not change further with aging. Norepinephrine-induced contractions initially increased in young age and then did not change further in older age. These findings suggest that during normal aging due to remodeling of arterial wall (smooth muscle) the contractile capacity of arteries increases, which seems to be independent from systemic blood pressure. Thus, arterial remodeling can favor the development of increased circulatory resistance in older age

Antibiotic resistance in Nicotiana.

The mode of action, and mechanism of resistance of many antibiotics are known since antibiotic resistance markers are commonly used in microbial genetics. Some of them, such as streptomycin, kanamycin and chloramphenicol selectively inhibit protein synthesis on the ''bacterial type'' ribosomes of the chloroplasts and mitochondria. Resistance to these antibiotics is, in some cases, coded by the organellar DNA, so these mutations are convenient markers in studies on organelle segregation, recombination and function in fungi and a 1 gae 1 The need for marker mutations in plant cell genetics, and our interest in cytoplasmic organelles, suggested to us the selection of antibiotic resistant cell lines in cell cultures of two species belonging to the genus Nicotiana~ N. tabacum and N. sylvestris. Streptomycin, kanamycin and chloramphenicol resistant lines described in flowering plants (N. tabacum~ N. sylvestris~ Petunia hybrida) and the moss, Physcomitrella patens~ have been reviewed. In the next sections some recent results on streptomycin, chloramphenicol and kanamycin resistance from our laboratory will follow