Composition and Chemical Variability of the Essential Oil from Aerial Parts of Cladanthus scariosus,an Endemic Species to the Moroccan High Atlas

Cladanthus scariosus (Ball) Oberpr. & Vogt is endemic to Moroccan High Atlas. It is known under the vernacular names Irezghi or Irezgui. Three essential oil samples have been isolated from aerial parts and analyzed by combination of chromatographic and spectroscopic techniques [gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC/MS) and ¹³C-NMR spectroscopy]. The compositions of oil samples were dominated by monoterpenes: α-pinene sabinene, and terpinen-4-ol. Chamazulene and dihydrochamazulene isomers as well as various hemiterpene esters and analogs have been identified. To evidence a chemical variability, statistical analysis performed on 13 oil sample compositions allowed partitioning into three groups, mainly differentiated by their contents of sabinene, camphor, borneol, terpinen-4-ol, and germacrene D.     

Biostimulants Derived from Moroccan Seaweeds: Seed Germination Metabolomics and Growth Promotion of Tomato Plant

Polysaccharides extracted from seaweeds can function as plant biostimulants. The aim of this study was to assess the effects of Polysaccharide Enriched Extracts (PEEs) obtained from 17 Moroccan seaweeds, on tomato seed germination and plant growth. Three concentrations (0.02, 0.05 and 0.1 mg mL⁻¹) of PEEs were applied to tomato seeds to evaluate their effect on 3 germination parameters: germination percentage (GP), germination speed (GS) and mean germination time (MGT). Metabolomic analysis by GC–MS was subsequently performed on seedlings. In the second experiment, four PEEs concentrations (0.02, 0.05, 0.1 and 0.2 mg mL⁻¹) were used as foliar spray or as soil application to tomato plants. Their growth parameters (number of leaves, shoot length, fresh and dry weight of stem and roots) and biochemical parameters (chlorophyll a and b) were measured. Results indicated a significant increase of GP and GS associated with a significant reduction of MGT of tomato seeds treated with 0.02 mg mL⁻¹ of PEEs obtained from Gigartina sp., Gigartina pistillata, Chondracanthus acicularis, Gelidium crinale, Schizymenia dubyi, Cystoseira. foeniculacea and Fucus spiralis. Similar results were also obtained by application of higher PEEs concentration (0.1 mg mL⁻¹) extracted from Ulva rigida, Codium tomentosum, Codium decorticatum and Bifurcaria bifurcata. Metabolomic analysis on seedlings detected the presence of some metabolites which could possibly be involved in seed germination enhancement or inhibition. The results of the second experiment showed that the same PEEs cited above at the same concentrations enhanced plant dry weight and chlorophyll a content except Gigartina sp., C. foeniculacea and C. decorticatum. Furthermore, soil application of PEEs was more effective in improving plant growth parameters than foliar application. The study shows the potential of PEEs from Moroccan seaweed to be used as biostimulants for a sustainable agriculture.

     

Comparison Between poly(dG-dC)·poly(dG-dC) and DNA Modified by cis-diamminedichloroplatinum (II): Immunological and Spectroscopic Studies

Abstract

The importance of the base composition and of the conformation of nucleic acids in the reaction with the drug cis-diamminedichloroplatinum(II) has been studied by competition experiments between the drug and several double-stranded polydeoxyribonucleotides. Binding to poly(dG)·poly(dC) is larger than to poly (dG-dC)·poly(dG-dC). There is no preferential binding in the competition between poly(dG-dC) ·poly(dG-dC), poly(dA-dC) ·poly(dG-dT) and poly(dA-dG)·poly(dC-dT). In the competition between poly(dG-dC) ·poly (dG-dC) (B conformation) and poly(dG-br⁵dC) ·poly(dG-br⁵dC) (Z conformation), the drug binds equally well to both polynucleotides. In natural DNA, modification of guanine residues in (GC)_n·(GC)_nsequences by the drug has been revealed by the inhibition of cleavage of these sequences by the restriction enzyme BssHII. By means of antibodies to platinated poly(dG-dC), it is shown that some of the adducts formed in platinated poly(dG-dC) are also formed in platinated pBR322 DNA. The type of adducts recognized by the antibodies is not known. Thin layer chromatography of the products after chemical and enzymatic hydrolysis of platinated poly(dG-dC) suggests that interstrand cross-links are formed. Finally, the conformations of poly(dG-m⁵dC) modified either by cis-diamminedichloroplatinum(II) or by trans-diammine- dichloroplatinum(II) have been compared by circular dichroism. Both the cis-isomer and the trans-isomer stabilize the Z conformation when they bind to poly(dG-m⁵dC) in the Z conformation. When they bind to poly(dG-m⁵dC) in the B conformation, the conformations of poly(dG-m⁵dC) modified by the cis or the trans-isomer are different. Moreover, the cis-isomer facilitates the B form-Z form transition of the unplatinated regions while the trans-isomer makes it more difficult.     

Aminoglycoside-derived cationic lipids as efficient vectors for gene transfection in vitro and in vivo

Background

Cationic lipids are at present very actively investigated for gene transfer studies and gene therapy applications. Basically, they rely on the formation of DNA/lipid aggregates via electrostatic interactions between their cationic headgroup and the negatively charged DNA. Although their structure/activity relationships are not well understood, it is generally agreed that the nature of the positive headgroup impacts on their transfection activity. Thus, we have directed our efforts toward the development of cationic lipids with novel cationic moieties. In the present work, we have explored the transfection potential of the lipophilic derivatives of the aminoglycoside kanamycin A. Indeed, aminoglycosides, which are natural polyamines known to bind to nucleic acids, provide a favorable scaffold for the synthesis of a variety of cationic lipids because of their structural features and multifunctional nature.

Methods and results

We report here the synthesis of a cationic cholesterol derivative characterized by a kanamycin A headgroup and of its polyguanidinylated derivative. The amino‐sugar‐based cationic lipid is highly efficient for gene transfection into a variety of mammalian cell lines when used either alone or as a liposomal formulation with the neutral phospholipid dioleoylphosphatidylethanolamine (DOPE). Its polyguanidinylated derivative was also found to mediate in vitro gene transfection. In addition, colloidally stable kanamycin‐cholesterol/DOPE lipoplexes were found to be efficient for gene transfection into the mouse airways in vivo.

Conclusions

These results reveal the usefulness of cationic lipids characterized by headgroups composed of an aminoglycoside or its guanidinylated derivative for gene transfection in vitro and in vivo. Copyright © 2002 John Wiley & Sons, Ltd.

     

Ameliorative Effect of Chrysin on Adenine-Induced Chronic Kidney Disease in Rats

Chrysin (5, 7- dihydroxyflavone) is a flavonoid with several pharmacological properties that include antioxidant, anti-inflammatory and antiapoptotic activities. in this work, we investigated some effects of three graded oral doses of chrysin (10, 50 and 250 mg/kg) on kidney structure and function in rats with experimental chronic renal disease (CKD) induced by adenine (0.25% w/w in feed for 35 days), which is known to involve inflammation and oxidative stress. Using several indices in plasma, urine and kidney homogenates, adenine was found to impair kidney function as it lowered creatinine clearance and increased plasma concentrations of creatinine, urea, neutrophil gelatinase-associated lipocalin and N-Acetyl-beta-D-glucosaminidase activity. Furthermore, it raised plasma concentrations of the uremic toxin indoxyl sulfate, some inflammatory cytokines and urinary albumin concentration. Renal morphology was severely damaged and histopathological markers of inflammation and fibrosis were especially increased. In renal homogenates, antioxidant indices, including superoxide dismutase and catalase activities, total antioxidant capacity and reduced glutathione were all adversely affected. Most of these adenine – induced actions were moderately and dose -dependently mitigated by chrysin, especially at the highest dose. Chrysin did not cause any overt adverse effect on the treated rats. The results suggest that different doses of chrysin produce variable salutary effects against adenine-induced CKD in rats, and that, pending further pharmacological and toxicological studies, its usability as a possible ameliorative agent in human CKD should be considered.     

Effects of density-dependent migrations on stability of a two-patch predator-prey model

We consider a predator-prey model in a two-patch environment and assume that migration between patches is faster than prey growth, predator mortality and predator-prey interactions. Prey (resp. predator) migration rates are considered to be predator (resp. prey) density-dependent. Prey leave a patch at a migration rate proportional to the local predator density. Predators leave a patch at a migration rate inversely proportional to local prey population density. Taking advantage of the two different time scales, we use aggregation methods to obtain a reduced (aggregated) model governing the total prey and predator densities. First, we show that for a large class of density-dependent migration rules for predators and prey there exists a unique and stable equilibrium for migration. Second, a numerical bifurcation analysis is presented. We show that bifurcation diagrams obtained from the complete and aggregated models are consistent with each other for reasonable values of the ratio between the two time scales, fast for migration and slow for local demography. Our results show that, under some particular conditions, the density dependence of migrations can generate a limit cycle. Also a co-dim two Bautin bifurcation point is observed in some range of migration parameters and this implies that bistability of an equilibrium and limit cycle is possible.     

Escherichia coli HdeB is an acid stress chaperone

We cloned, expressed, and purified the hdeB gene product, which belongs to the hdeAB acid stress operon. We extracted HdeB from bacteria by the osmotic-shock procedure and purified it to homogeneity by ion-exchange chromatography and hydroxyapatite chromatography. Its identity was confirmed by mass spectrometry analysis. HdeB has a molecular mass of 10 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which matches its expected molecular mass. We purified the acid stress chaperone HdeA in parallel in order to compare the two chaperones. The hdeA and hdeB mutants both display reduced viability upon acid stress, and only the HdeA/HdeB expression plasmid can restore their viability to close to the wild-type level, suggesting that both proteins are required for optimal protection of the bacterial periplasm against acid stress. Periplasmic extracts from both mutants aggregate at acidic pH, suggesting that HdeA and HdeB are required for protein solubilization. At pH 2, the aggregation of periplasmic extracts is prevented by the addition of HdeA, as previously reported, but is only slightly reduced by HdeB. At pH 3, however, HdeB is more efficient than HdeA in preventing periplasmic-protein aggregation. The solubilization of several model substrate proteins at acidic pH supports the hypothesis that, in vitro, HdeA plays a major role in protein solubilization at pH 2 and that both proteins are involved in protein solubilization at pH 3. Like HdeA, HdeB exposes hydrophobic surfaces at acidic pH, in accordance with the appearance of its chaperone properties at acidic pH. HdeB, like HdeA, dissociates from dimers at neutral pH into monomers at acidic pHs, but its dissociation is complete at pH 3 whereas that of HdeA is complete at a more acidic pH. Thus, we can conclude that Escherichia coli possesses two acid stress chaperones that prevent periplasmic-protein aggregation at acidic pH.     

Kinetics of albumin- and alpha-fetoprotein-production during rat liver development

Synthesis of most of the plasma proteins is one of the main functions of the hepatocytes. Albumin synthesis is quantitatively the most abundant. In the present study we investigated albumin- and alpha-fetoprotein-gene-expression, and the function of the secretory apparatus during rat liver development. To this purpose we used the method of radioactive biosynthetic labeling of newly synthesized albumin and alpha-fetoprotein (AFP) to monitor the secretory capacity of endodermal cells derived from ventral foregut region (embryonic day 10, E10), and of embryonic and fetal hepatoblasts. Synthesis and secretion of albumin and AFP were already detected in the low numbered ventral foregut endodermal cells; fibrinogen synthesis was detectable in the E12 hepatoblasts, which were in higher number. The whole secretory machinery was functional from the earliest stages of liver development, and the speed of secretion was comparable with that of the adult hepatocytes. There was almost 4-fold increase of hepatoblasts cell volume in fetal stage compared with embryonic stage. The model used suggests that the hepatocyte secretory apparatus is already functional before the emergence of the liver bud. This is the first comparative report to analyze the hepatocyte secretory function, cell proliferation and cell volume during liver development.