Correlations between the compositional properties of human genes,codon usage,and amino acid composition of proteins

Summary We have analyzed the correlation that exists between the GC levels of third and first or second codon position for about 1400 human coding sequences. The linear relationship that was found indicates that the large differences in GC level of third codon positions of human genes are paralleled by smaller differences in GC levels of first and second codon positions. Whereas third codon position differences correspond to very large differences in codon usage within the human genome, the first and second codon position differences correspond to smaller, yet very remarkable, differences in the amino acid composition of encoded proteins. Because GC levels of codon positions are linearly correlated with the GC levels of the isochores harboring the corresponding genes, both codon usage and amino acid composition are different for proteins encoded by genes located in isochores of different GC levels. Furthermore, we have also shown that a linear relationship with a unity slope and a correlation coefficient of 0.77 exists between GC levels of introns and exons from the 238 human genes currently available for this analysis. Introns are, however, about 5% lower in GC, on average, than exons from the same genes.     

Structure,electronic properties,and NBO and TD-DFT analyses of nickel(II), zinc(II), and palladium(II) complexes based on Schiff-base ligands

In this work we studied the structural and electronic properties of the metal–Schiff base complexes Ni\( {\mathrm{L}}_2^2 \) (1), Pd\( {\mathrm{L}}_2^1 \) (2), Zn\( {\mathrm{L}}_2^2 \) (3), and Ni\( {\mathrm{L}}_2^1 \)(4), where L¹ and L² are Schiff bases synthesized from salicylaldehyde and 2-hydroxy-5-methylbenzaldehyde, respectively. Natural bond analysis showed that in complexes 1 and 2, the metal ion coordinates to the ligands through electron donation from lone pairs on ligand nitrogen and oxygen atoms to s and d orbitals on the metal ion. In complex 3, metal–N and metal–O bonds are formed through charge transfer from the lone pairs on nitrogen and oxygen atoms to an s orbital of Zn. Dimethylation of the phenolate rings in the ligands decreases the energy gap and redshifts the spectrum of the nickel complex. The main absorptions observed were assigned on the basis of singlet-state transitions. The simulated spectra of the two complexes 1 and 2 are characterized by excited states with ligand-to-ligand charge-transfer (LLCT), metal-to-ligand charge-transfer (MLCT), ligand-to-metal charge-transfer (LMCT), and metal-centered (MC) character.

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Graphical abstract Geometric structure of the palladium complex.

     

Comparison of pistachio hull essential oils from different Tunisian localities

Pistachio (Pistacia vera L.) fruit is well known for its oleaginous and edible seed. Less information is available about the hull constituted by the epicarp and the mesocarp. This part of the fruit contains an essential oil that can be valorized. Tunisia is one of the countries cultivating pistachio trees. This work presents essential oil composition of pistachio hulls (Mateur variety) from different geographical localities: Grombalia (North-East), Kairouan (Middle) and Sfax (Middle-East). Yields were more important in Sfax samples (0.53% on a dry weight basis). Alpha-terpinolene was the major compound for Grombalia fruits (35.7%), whereas Kairouan and Sfax samples where characterized by alpha-pinene (42.5 and 43.8% respectively). For all samples, monoterpene hydrocarbons predominated (more than 79.8% of the essential oil).     

Variations in the essential oil composition from different parts of Coriandrum sativum L. cultivated in Tunisia

Essential oils obtained by hydrodistillation from different organs (flowers, leaves, stems and roots) of Tunisian coriander (Coriandrum sativum L.) was analyzed. GC and GC-MS analysis enabled us to identify 64 compounds and revealed great qualitative and quantitative differences between the analyzed parts. In all organs, the main compound was (E)-2-dodecenal, followed by (E)-2-tridecenal, gamma-cadinene, (Z)-myroxide, neryl acetate and eugenol. Multivariate analysis (PCA) revealed a high similarity in the essential oils composition between upper leaves and flowers in one hand and basal leaves, roots and stems on the other hand. Further, it has been reported an organ-dependant distribution of essential oil compounds.     

Nitrogen effects on proteins, chlorophylls and fatty acids during the growth of Arthrospira platensis

Spirulina platensis (=Arthrospira platensis) is a tunisian strain which has been isolated for the first time in Oued Essed (Sousse, Sidi Bou Ali). Biomass evolution, proteins, chlorophylls and fatty acids composition of this alga were monitored by varying nitrogen concentrations in the culture medium. Nitrogen stress was provoked by adding sodium nitrate (NaNO3) in the culture medium with concentrations varying from 0 to 5 g/l. Results obtained showed that nitrogen depletion increased total proteins and total chlorophylls. The addition of NaNO3 (5g/l) led to an increase of total fatty acids amounts and modify fatty acids composition. Optimal quantities of palmitic, gamma -linolenic and oleic acids were obtained with NaNO3 free-cultures. Thus, the tunisian strain has valuable biological substances, worthy to determine the optimal conditions for its propagation.     

Super-resolution Microscopy Approaches for Live Cell Imaging

By delivering optical images with spatial resolutions below the diffraction limit, several super-resolution fluorescence microscopy techniques opened new opportunities to study biological structures with details approaching molecular structure sizes. They have now become methods of choice for imaging proteins and their nanoscale dynamic organizations in live cells. In this mini-review, we describe and compare the main far-field super-resolution approaches that allow studying endogenous or overexpressed proteins in live cells.     

Transfer of the AQP1 cDNA for the correction of radiation-induced salivary hypofunction

The treatment of most patients with head and neck cancer includes ionizing radiation (IR). Salivary glands in the IR field suffer significant and irreversible damage, leading to considerable morbidity. Previously, we reported that adenoviral (Ad)-mediated transfer of the human aquaporin-1 (hAQP1) cDNA to rat [C. Delporte, B.C. O'Connell, X. He, H.E. Lancaster, A.C. O'Connell, P. Agre, B.J. Baum, Increased fluid secretion after adenoviral-mediated transfer of the aquaporin-1 cDNA to irradiated rat salivary glands. Proc. Natl. Acad. Sci. U S A. 94 (1997) 3268-3273] and miniature pig [Z. Shan, J. Li, C. Zheng, X. Liu, Z. Fan, C. Zhang, C.M. Goldsmith, R.B. Wellner, B.J Baum, S. Wang. Increased fluid secretion after adenoviral-mediated transfer of the human aquaporin-1 cDNA to irradiated miniature pig parotid glands. Mol. Ther. 11 (2005) 444-451] salivary glands ∼16 weeks following IR resulted in a dose-dependent increase in salivary flow to ≥80% control levels on day 3. A control Ad vector was without any significant effect on salivary flow. Additionally, after administration of Ad vectors to salivary glands, no significant lasting effects were observed in multiple measured clinical chemistry and hematology values. Taken together, the findings show that localized delivery of AdhAQP1 to IR-damaged salivary glands is useful in transiently increasing salivary secretion in both small and large animal models, without significant general adverse events. Based on these results, we are developing a clinical trial to test if the hAQP1 cDNA transfer strategy will be clinically effective in restoring salivary flow in patients with IR-induced parotid hypofunction.