Elias Baydoun

The immobility of pectic substances in injured tomato leaves and its bearing on the identity of the wound hormone

It has been suggested that pectic polysaccharides (or oligosaccharides cleaved from them) are liberated from the cell wall upon wounding of leaf tissue, and that they act as long-distance hormones evoking a defence response in neighbouring uninjured leaves (P.D. bishop et al. 1981, Proc. Natl. Acad. Sci. USA 78, 3536–3540, and cited literature). We have tested this hypothesis by infiltration of radioactive pectic fragments (rhamnogalacturonans and homogalacturonans of degrec of polymerisation down to 6) into wounds on tomato leaves. No radioactivity was exported from the treated leaf. [14C]Sucrose, applied in the same way, was effectively translocated, probably via the phloem. We suggest that pectic substances are not themselves long-distance wound hormones. The possibility remains that pectic substances, solubilised on wounding, act in the immediate vicinity of the wound to stimulate the dispatch of a second messenger, which would be the long-distance wound hormone.

Antimicrobial resistance of Listeria monocytogenes isolated from dairy-based food products.

In this study Listeria monocytogenes (L. monocytogenes) was isolated from three traditionally consumed Lebanese dairy-based food products. One hundred and sixty four samples (45 samples of Baladi cheese, 36 samples of Shankleesh and 83 of Kishk) were collected from the Bekaa Valley in the Northeast region of Lebanon. Suspected Listeria colonies were selected and initially identified by using standard biochemical tests. Initial identification of the positive L. monocytogenes colonies was confirmed at the molecular level by Polymerase Chain Reaction (n=30) and the confirmed isolates were evaluated for their susceptibility to 10 commonly used antimicrobials. All of the 30 isolates were confirmed to be L. monocytogenes yielding a PCR product of approximately 660 base pairs (bp). L. monocytogenes was detected in 26.67%, 13.89% and 7.23% of the Baladi cheese, Shankleesh and Kishk samples, respectively. The highest resistance in L. monocytogenes isolates was noted against oxacillin (93.33%) followed by penicillin (90%). The results provide an indication of the contamination levels of dairy-based foods in Lebanon and highlight the emergence of multi-drug resistant Listeria in the environment.

Biotechnology and the developing world

The life sciences offer opportunities for revolutionizing human welfare activities. Enriched by inputs from genomic research, biotechnology is a major force for development in all countries. Entwined with culture and socio-ethical values, biotechnology contributes to solving problems like food and water insecurity that impede national development and threaten peace in the developing world. The lack of facilities and professional skills in biotechnology limits R & D initiatives in the developing and the least developed countries (LDCs); and, restricts their full participation in take-off activities in national and self-reliant regional ventures in sustainable development. The practice of biotechnology different in many developing countries is nevertheless impressive. The establishment of biotechnology parks and medicinal plant farms in several developing countries is indicative of biotechnology being accorded high policy status in national development; of its significance in the eradication of poverty; and of its use in the empowerment of women in applying the technology for human and social welfare. This review provides several examples of different types of biotech activities that are being employed for development in the developing world.

In vivo Degradation and Extracellular Polymer-Binding of Xyloglucan Nonasaccharide, a Naturally-Occurring Anti-Auxin

Summary 1-10 nM Xyloglucan nonasaccharide (XG9) and its naturally-occurring acylated derivatives (XG9·Ac) antagonise the growth-promoting action of 1μM 2,4-dichlorophenoxyacetic acid in pea stem segments. To investigate the mechanisms involved in controlling the in vivo concentrations of these biologically-active oligosaccharides, we 3 H-labelled XG9 and XG9·Ac in their xylose or fucose residues, fed them at 10 nM to rapidly-growing Spinacia cell cultures, and monitored their fate by gel-permeation chromatography. Very little breakdown to low-M r products took place, and little 3 H entered or bound to the cells. However, a proportion of the 3 H appeared to become linked to a soluble, extracellular polymer. The linkage was stable to 31% acetic acid and to 0.5M NaOH at 25°C, but Trichoderma cellulase was able to disrupt it, liberating a [ 3 H]oligosaccharide similar to XG9. We speculate that XG9 and XG9·Ac became attached to soluble extracellular xyloglucans by transglycosylation.

The apoptotic and anti-proliferative activity of 'Origanum majorana' extracts on human leukemic cell line

Scientists are constantly searching for phytochemicals and compounds with anti-cancer and antioxidant activity. In this study, the anti-proliferative activity of plant extracts from Origanum majorana (marjoram) was tested on human lymphoblastic leukemia cell line Jurkat. Cytotoxicity was examined using non-radioactive cytotoxicity assay and the IC(50) was calculated. At non-cytotoxic concentrations, the viability of cells decreased with increase of concentration of plant extract. The anti-proliferative effect was also found to be dose-dependent. Analysis via flow cytometry shows that marjoram extracts stimulated apoptosis. Induction of apoptosis was caused by an up-regulation of p53 protein levels and down-regulation of Bcl-2alpha. Marjoram exhibited a strong scavenging activity (SC(50)=0.03mg dry weight). The conclusions from this study suggest that marjoram extracts exhibit anti-proliferative effect and high antioxidant activity. For that it merits further investigation as a potential therapeutic agent.

[2-3H]Mannose Incorporation in Cultured Plant Cells: Investigation of L-Galactose Residues of the Primary Cell Wall

Summary D -[2-3H]Mannose was tested as a precursor for the labelling of L -galactose residues in cell wall polysaccharides where D -galactose residues predominate. Cultured cells of spinach, rose and maize rapidly took up [2-3H]mannose (e.g. 50 % in 4–8 min). About 90 % of the 3H supplied was converted to 3H2O, the remaining 10 % being incorporated into polymers. Of the 3H incorporated into spinach polymers, 43 % was recovered in D -mannose, 37 % in L -fucose and 5 % in L -galactose residues. D -Galactose residues were not labelled. The L -[3H]galactose residues appeared to be in the pyranose form, and were released from the polymer in the form of short oligosaccharides upon treatment with «Driselase». L -[3H]Galactose residues were found in the phenol/acetic acid/H20 soluble, cold water soluble, pectic and hemicellulosic fractions of the total cell polymers, and were thus not confined to any one particular polymer. The D -galactose: L -galactose ratio in spinach polymers was ca. 70:1.

Antibacterial Activity of the Extracts Obtained from Rosmarinus officinalis, Origanum majorana, and Trigonella foenum-graecum on Highly Drug-Resistant Gram Negative Bacilli

Our aim was to determine the antimicrobial activity of three selected plants ( Rosmarinus officinalis, Origanum majorana, and Trigonella foenum-graecum) against Extended Spectrum Beta Lactamase (ESBL)—producing Escherichia coli and Klebsiella pneumoniae— and to identify the specific plant fraction responsible for the antimicrobial activity. The plants were extracted with ethanol to yield the crude extract which was further subfractionated by different solvents to obtain the petroleum ether, the dichloromethane, the ethyl acetate, and the aqueous fractions. The Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentrations (MBC) were determined using broth microdilution. The MICs ranged between 1.25 and 80  𝜇 g / 𝜇 l . The majority of these microorganisms were inhibited by 80 and 40  𝜇 g / 𝜇 l of the crude extracts. The petroleum ether fraction of Origanum majorana significantly inhibited 94% of the tested strains. Ethyl acetate extracts of all selected plants exhibited relatively low MICs and could be therefore described as strong antibacterial.

Microbial transformation of nandrolone with Cunninghamella echinulata and Cunninghamella blakesleeana and evaluation of leishmaniacidal activity of transformed products

Therapeutic potential of nandrolone and its derivatives against leishmaniasis has been studied. A number of derivatives of nandrolone (1) were synthesized through biotransformation. Microbial transformation of nandrolone (1) with Cunninghamella echinulata and Cunninghamella blakesleeana yielded three new metabolites, 10β,12β,17β-trihydroxy-19-nor-4-androsten-3-one (2), 10β,16α,17β-trihydroxy-19-nor-4-androsten-3-one (3), and 6β,10β,17β-trihydroxy-19-nor-4-androsten-3-one (4), along with four known metabolites, 10β,17β-dihydroxy-19-nor-4-androsten-3-one (5), 6β,17β-dihydroxy-19-nor-4-androsten-3-one (6) 10β-hydroxy-19-nor-4-androsten-3,17-dione (7) and 16β,17β-dihydroxy-19-nor-4-androsten-3-one (8). Compounds 1-8 were evaluated for their anti-leishmanial activity. Compounds 1 and 8 showed a significant activity in vitro against Leishmania major. The leishmanicidal potential of compounds 1-8 (IC50=32.0±0.5, >100, 77.39±5.52, 70.90±1.16, 54.94±1.01, 80.23±3.39, 61.12±1.39 and 29.55±1.14 μM, respectively) can form the basis for the development of effective therapies against the protozoal tropical disease leishmaniasis.

The Antiproliferative Effect of Kefir Cell-Free Fraction on HuT-102 Malignant T Lymphocytes

Kefir is produced by adding kefir grains (a mass of proteins, polysaccharides, bacteria, and yeast) to pasteurized milk; it has been shown to control several cellular types of cancer, such as Sarcoma 180 in mice, Lewis lung carcinoma, and human mammary cancer. Human T-cell lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia, which is a fatal disease with no effective treatment. The current study aims at investigating the effect of a cell-free fraction of kefir on HuT-102 cells, which are HTLV-1-positive malignant T-lymphocytes. Cells were incubated with different kefir concentrations: the cytotoxicity of the compound was evaluated by determining the percentage viability of cells. The effect of all the noncytotoxic concentrations of kefir cell-free fraction on the proliferation of HuT-102 cells was then assessed. The levels of transforming growth factor (TGF)-alpha mRNA upon kefir treatment were then analyzed using reverse transcriptase polymerase chain reaction. Finally, the growth inhibitory effects of kefir on cell cycle progression and/or apoptosis were assessed by flow cytometry. The maximum cytotoxicity recorded at 80 microg/microL for 48 hours was only 43%. The percent reduction in proliferation was very significant, dose and time dependent, and reached 98% upon 60-microg/microL treatment for 24 hours. Kefir cell-free fraction caused the downregulation of TGF-alpha, which is a cytokine that induces the proliferation and replication of cells. Finally, a marked increase in cell cycle distribution was noted in the pre-G1 phase. In conclusion, kefir is effective in inhibiting proliferation and inducing apoptosis of HTLV-1-positive malignant T-lymphocytes. Therefore, further in vivo investigation is highly recommended.

Genotypic variation in the germination of common bean in response to cold temperature stress

Beans (Phaseolus vulgaris) are regarded as a susceptible crop to suboptimal temperatures. In temperate regions, low temperatures reduce establishment of beans when planted early in the growing season. Seeds of 14 cultivars/lines or beans were germinated in petri dishes at a constant 8, 10, 12, or 18°C or at 12 h alternating temperatures of 10/8, 12/8 or 18/8°C. Differences in germination percentages and rates between cultivars/lines were significant, especially at low temperatures. Cultivars/lines that germinated best and quickly at constant 8°C were ‘Volare’, ‘Great Northern (G.N.) Tara’, ‘G.N. Belneb # 1’, ‘G.N. Spinel’, and ‘San Cristobal’. Germination percent and rate of ‘Pinto-UI-111’ and ‘Canadian Wonder’ increased significantly when temperatures were increased by 2 to 4°C for 12 h per 24 h, compared with a constant 8°C. Whereas, germination of ‘G.N. Belneb # 1’ was reduced. Polyacrylamide gel electrophoresis was used to study the effect of cold treatment on polypeptide patterns of seven cultivars/lines. Seeds were germinated at 18°C constant for 96 h or at 18°C for 48 h followed by 48 h at 2 or 8°C. During cold treatment the synthesis of some polypeptides increased. ‘Volare’, ‘G.N. Tara’ ‘Pinto-UI-111’ and ‘Canadian Wonder’ showed changes in polypeptide patterns, while Alubia-33-1, ‘Michigan 84100’ and BAT-1225 showed no changes in polypeptide patterns if compared to the control (96 h at 18°C in the dark). This suggests a likely essential role of these proteins in the development of chilling tolerance.