Cold Stress, Freezing Adaptation, Varietal Susceptibility of Olea europaea L.: A Review.

Olive (Olea europaea L.) is an evergreen xerophytic tree characterizing vegetative landscape and historical-cultural identity of the Mediterranean Basin. More than 2600 cultivars constitute the rich genetic patrimony of the species cultivated in approximately 60 countries. As a subtropical species, the olive tree is quite sensitive to low temperatures, and air temperature is the most critical environmental factor limiting olive tree growth and production. In this present review, we explored the detrimental effects caused of low temperatures on olive cultivars, and analyzed the most frequently experimental procedures used to evaluate cold stress. Then, current findings freezing stress physiology and gene are summarized in olive tree, with an emphasis on adaptive mechanisms for cold tolerance. This review might clear the way for new research on adaptive mechanisms for cold acclimation and for improvement of olive growing management.

Differentially expressed genes in Hirudo medicinalis ganglia after acetyl-L-carnitine treatment.

Acetyl-L-carnitine (ALC) is a naturally occurring substance that, when administered at supra-physiological concentration, is neuroprotective. It is involved in membrane stabilization and in enhancement of mitochondrial functions. It is a molecule of considerable interest for its clinical application in various neural disorders, including Alzheimer's disease and painful neuropathies. ALC is known to improve the cognitive capability of aged animals chronically treated with the drug and, recently, it has been reported that it impairs forms of non-associative learning in the leech. In the present study the effects of ALC on gene expression have been analyzed in the leech Hirudo medicinalis. The suppression subtractive hybridisation methodology was used for the generation of subtracted cDNA libraries and the subsequent identification of differentially expressed transcripts in the leech nervous system after ALC treatment. The method detects differentially but also little expressed transcripts of genes whose sequence or identity is still unknown. We report that a single administration of ALC is able to modulate positively the expression of genes coding for functions that reveal a lasting effect of ALC on the invertebrate, and confirm the neuroprotective and neuromodulative role of the substance. In addition an important finding is the modulation of genes of vegetal origin. This might be considered an instance of ectosymbiotic mutualism.

Modulation of myelin basic protein gene expression by acetyl-L-carnitine.

Acetyl-L-carnitine (ALC), the acetyl ester of L-carnitine, is a naturally occurring molecule which plays an essential role in intermediary and mitochondrial metabolism. It has also neurotrophic and antioxidant actions, demonstrating efficacy and high tolerability in the treatment of neuropathies of various etiologies. ALC is a molecule of considerable interest for its clinical application in various neural disorders, although little is known regarding its effects on gene expression. Suppression subtractive hybridization methodology was used for the generation of subtracted complementary DNA libraries and the subsequent identification of differentially expressed transcripts in the rat brain after chronic ALC treatments. We provided evidence for a downregulation of the expression of all of the isoforms of myelin basic protein gene following prolonged ALC treatment, indicating a possible role in the modulation of myelin basic protein turnover, stabilizing and maintaining myelin integrity.

Isolation and expression analysis of low temperature-induced genes in white poplar (Populus alba).

Poplar is an important crop and a model system to understand molecular processes of growth, development and responses to environmental stimuli in trees. In this study, we analyzed gene expression in white poplar (Populus alba) plants subjected to chilling. Two forward suppression-subtractive-hybridization libraries were constructed from P. alba plants exposed to low non-freezing temperature for 6 or 48h. Hundred and sixty-two cDNAs, 54 from the 6-h library and 108 from the 48-h library, were obtained. Isolated genes belonged to six categories of genes, specifically those that: (i) encode stress and defense proteins; (ii) are involved in signal transduction; (iii) are related to regulation of gene expression; (iv) encode proteins involved in cell cycle and DNA processing; (v) encode proteins involved in metabolism and energetic processes; and (vi) are involved in protein fate. Different expression patterns at 3, 6, 12, 24, 48h at 4 degrees C and after a recovery of 24h at 20 degrees C were observed for isolated genes, as expected according to the class in which the gene putatively belongs. Forty-four of 162 genes contained DRE/LTRE cis-elements in the 5' proximal promoter of their orthologs in Populus trichocarpa, suggesting that they putatively belong to the CBF regulon. The results contribute new data to the list of possible candidate genes involved in cold response in poplar.

In the rat brain acetyl-L-carnitine treatment modulates the expression of genes involved in neuronal ceroid lipofuscinosis.

Acetyl-L-carnitine (ALC) is a naturally occurring substance that, when administered at supraphysiological concentration, is neuroprotective. It is a molecule of considerable interest for its clinical application in various neural disorders, including Alzheimer's disease and painful neuropathies. Suppression subtractive hybridization methodology was used for the generation of subtracted cDNA libraries and the subsequent identification of differentially expressed transcripts in the rat brain after ALC treatment. The method generates an equalized representation of differentially expressed genes irrespective of their relative abundance and it is based on the construction of forward and reverse cDNA libraries that allow the identification of the genes which are regulated by ALC. We report that ALC treatment: (1) upregulates lysosomal H(+)/ATPase gene expression and (2) downregulates myelin basic protein gene expression. The expression of these genes is altered in some forms of neuronal ceroid lipofuscinosis (NCL) pathologies. In this case, ALC might rebalance the disorders underlying NCL disease represented by a disturbance in pH homeostasis affecting the acidification of vesicles transported to lysosomal compartment for degradation. This study provides evidence that ALC controls genes involved in these serious neurological pathologies and provides insights into the ways in which ALC might exert its therapeutic benefits.

Identification of differentially expressed genes induced by ozone stress in sensitive and tolerant poplar hybrids.

The differential expression of genes induced by an acute ozone treatment was analysed in two poplar clones, i.e. Populus deltoides x maximowiczii, Eridano clone, and Populus x euoramericana, I-214 clone, respectively, sensitive and tolerant to this pollutant, performing suppression subtractive hybridization (SSH). From the obtained cDNA libraries several clones were obtained, which corresponded to differentially regulated genes. Preliminary expression analyses of four genes, Fs23A-LRP, Ft33B-CaBP, Ft312B-WRKY, and Ft32C-WAK identified by the primary screening, were conducted by semi-quantitative RT-PCR to evaluate the ozone responsiveness of the libraries. The most interesting finding is the co-activation of a wall associated kinase and a WRKY transcription factor in response to O(3) stress.

Acetyl-L-carnitine up-regulates expression of voltage-dependent anion channel in the rat brain.

Acetyl-L-carnitine (ALC) exerts unique neuroprotective, neuromodulatory, and neurotrophic properties, which play an important role in counteracting various pathological processes, and have antioxidative properties, protecting cells against lipid peroxidation. In this study, suppression subtractive hybridization (SSH) method was applied for the generation of subtracted cDNA libraries and the subsequent identification of differentially expressed transcripts after treatment of rats with ALC. The technique generates an equalized representation of differentially expressed genes irrespective of their relative abundance and it is based on the construction of forward and reverse cDNA libraries that allow the identification of the genes that are regulated after ALC treatment. In the present paper, we report the identification of the gene of mitochondrial voltage-dependent anion channel (VDAC) protein which is positively modulated by the ALC treatment. VDAC is a small pore-forming protein of the mitochondrial outer membrane. It represents an interesting tool for Ca(2+) homeostasis, and it plays a central role in apoptosis. In addition, VDAC seems to have a relevant role in the synaptic plasticity.

Identification of differentially expressed genes induced in the rat brain by acetyl-L-carnitine as evidenced by suppression subtractive hybridisation.

Acetyl-L-carnitine (ALC) is a molecule widely present in the central nervous system (CNS) formed by the reversible acetylation of carnitine. It acts by stimulating energy metabolism. Reported neurobiological effects of this substance include modulation of brain energy and phospholipid metabolism; cellular macromolecules (including neurotrophic factors and neurohormones); synaptic transmission of multiple neurotransmitters. ALC is of considerable interest for its clinical application in Alzheimer's disease and in the treatment of painful neuropathies. There are experimental data that it affects attention and antagonizes deterioration of ability to learn, improving long-term memory. Moreover, ALC influences nonassociative learning of sensitization type in Hirudo medicinalis. These findings are suggesting that ALC might exert its effects by means of new protein synthesis. ALC or saline solution was injected intraperitoneally each day for 21 days in rats. Poly(A)+ RNAs were isolated from control and treated rat brain. Suppression subtractive hybridisation (SSH) method was applied for the generation of subtracted cDNA libraries and the subsequent identification of differentially expressed transcripts after treatments. The technique generates an equalized representation of differentially expressed genes irrespective of their relative abundance, and it is based on the construction of forward and reverse cDNA libraries that allow the identification of the genes that are regulated or switched off/on after ALC treatment. We identified two modulated genes, the isoform gamma of 14-3-3 protein and a precursor of ATP synthase lipid-binding protein, and one gene switched on by the treatment, the heat shock protein hsp72.