Hany A. El-Shemy

Potassium deficiency affects water status and photosynthetic rate of the vegetative sink in green house tomato prior to its effects on source activity

The potassium requirement of green house tomatoes is very high for vegetative growth and fruit production. Potassium deficiency in plants takes long time for expression of visible symptoms. The objective of this study is to detect the deficiency early during the vegetative growth and define the roles of aquaporin and K-channel transporters in the process of regulation of water status and source-sink relationship. The tomato plants were grown hydroponically inside green house of Hiroshima University, Japan and subjected to different levels of K in the rooting medium. Potassium deficiency stress decreased photosynthesis, expansion and transport of ¹⁴C assimilates of the source leaf, but the effects became evident only after diameter expansion of the growing stem (sink) was down-regulated. The depression of stem diameter expansion is assumed to be associated with the suppression of water supply more than photosynthate supply to the organ. The stem diameter expansion is parameterized by root water uptake and leaf transpiration rates. The application of aquaporin inhibitor (AgNO₃) decreased leaf water potential, stem expansion and root hydraulic conductance within minutes of application. Similar results were obtained for application of the K-channel inhibitors. These observations suggested a close relationship between stem diameter expansion and activities of aquaporins and K-channel transporters in roots. The deficiency of potassium might have reduced aquaporin activity, consequently suppressing root hydraulic conductance and water supply to the growing stem for diameter expansion and leaf for transpiration. We conclude that close coupling between aquaporins and K-channel transporters in water uptake of roots is responsible for regulation of stem diameter dynamics of green house tomato plants.

Active principle from Moringa oleifera Lam leaves effective against two leukemias and a hepatocarcinoma

Medicinal plants are important elements of indigenous medical system that have persisted in developing countries. Many of the pharmacological principles currently used as anticancer agents were first isolated from plants. However, some important anticancer agents are still extracted from plants because they cannot be synthesized chemically on a commercial scale due to their complex structures that often contain several chiral centers. The aim of this study was to test different extracts from the leaves of Moringa or drumstick tree ( Moringa oleifera ) for activity against leukemia and hepatocarcinoma cells in vitro . The extracts could kill majority (70 - 86%) of the abnormal cells among primary cells harvested from 10 patients with acute lymphoblastic leukemia (ALL) and 15 with acute myeloid leukemia (AML) as well as a culture of hepatocarcinoma cells (75% death), but most significantly by the hot water and ethanol extracts. In conclusion, M. oleifera may have potential for use as source of natural treatment for diseases such as cancer.

Allelopathic Effects of Water Hyacinth [Eichhornia crassipes]

Eichhornia crassipes (Mart) Solms is an invasive weed known to out-compete native plants and negatively affect microbes including phytoplankton. The spread and population density of E. crassipes will be favored by global warming. The aim here was to identify compounds that underlie the effects on microbes. The entire plant of E. crassipes was collected from El Zomor canal, River Nile (Egypt), washed clean, then air dried. Plant tissue was extracted three times with methanol and fractionated by thin layer chromatography (TLC). The crude methanolic extract and five fractions from TLC (A–E) were tested for antimicrobial (bacteria and fungal) and anti-algal activities (green microalgae and cyanobacteria) using paper disc diffusion bioassay. The crude extract as well as all five TLC fractions exhibited antibacterial activities against both the Gram positive bacteria; Bacillus subtilis and Streptococcus faecalis; and the Gram negative bacteria; Escherichia coli and Staphylococcus aureus. Growth of Aspergillus flavus and Aspergillus niger were not inhibited by either E. crassipes crude extract nor its five fractions. In contrast, Candida albicans (yeast) was inhibited by all. Some antialgal activity of the crude extract and its fractions was manifest against the green microalgae; Chlorella vulgaris and Dictyochloropsis splendida as well as the cyanobacteria; Spirulina platensis and Nostoc piscinale. High antialgal activity was only recorded against Chlorella vulgaris. Identifications of the active antimicrobial and antialgal compounds of the crude extract as well as the five TLC fractions were carried out using gas chromatography combined with mass spectroscopy. The analyses showed the presence of an alkaloid (fraction A) and four phthalate derivatives (Fractions B–E) that exhibited the antimicrobial and antialgal activities.

Antitumor Properties and Modulation of Antioxidant Enzymes Activity by Aloe vera Leaf Active Principles Isolated via Supercritical Carbon Dioxide Extraction

The aim of this study was to evaluate the potential anticancer properties and modulatory effect of selected Aloe vera (A. vera) active principles on antioxidant enzyme activities. Thus, three anthraquinones (Namely: aloesin, aloe-emodin and barbaloin) were extracted from A. vera leaves by supercritical fluid extraction and subsequently purified by high performance liquid chromatography. Additionally, the N-terminal octapeptide derived from verectin, a biologically active 14 kDa glycoprotein present in A. vera, was also tested. In vivo, active principles exhibited significant prolongation of the life span of tumor-transplanted animals in the following order: barbaloin> octapeptide> aloesin > aloe-emodin. A. vera active principles exhibited significant inhibition on Ehrlich ascite carcinoma cell (EACC) number, when compared to positive control group, in the following order: barbaloin> aloe-emodin > octapeptide > aloesin. Moreover, in trypan blue cell viability assay, active principles showed a significant concentration-dependent cytotoxicity against acute myeloid leukemia (AML) and acute lymphocytes leukemia (ALL) cancerous cells. Furthermore, in MTT cell viability test, aloe-emodin was found to be active against two human colon cancer cell lines (i.e. DLD-1 and HT2), with IC(50) values of 8.94 and 10.78 microM, respectively. Treatments of human AML leukemic cells with active principles (100 microg ml(-1)) resulted in varying intensities of internucleosomal DNA fragmentation, hallmark of cells undergoing apoptosis, in the following order: aloe-emodin> aloesin> barbaloin> octapeptide. Intererstingly, treatment of EACC tumors with active principles resulted in a significant elevation activity of key antioxidant enzymes (SOD, GST, tGPx, and LDH). Our data suggest that the tested A. vera compounds may exert their chemo-preventive effect through modulating antioxidant and detoxification enzyme activity levels, as they are one of the indicators of tumorigenesis. These findings are discussed in the light of the potential of A. vera plant extracts for developing efficient, specific and non-toxic anticancer drugs that are affordable for developing countries.

High temperature effects on photosynthate partitioning and sugar metabolism during ear expansion in maize (Zea mays L.) genotypes

Short hot and dry spells before, or during, silking have an inordinately large effect on maize (Zea mays L.; corn) grain yield. New high yielding genotypes could be developed if the mechanism of yield loss were more fully understood and new assays developed. The aim here was to determine the effects of high temperature (35/27 degrees C) compared to cooler (25/18 degrees C) temperatures (day/night). Stress was applied for a 14 d-period during reproductive stages prior to silking. Effects on whole plant biomass, ear development, photosynthesis and carbohydrate metabolism were measured in both dent and sweet corn genotypes. Results showed that the whole plant biomass was increased by the high temperature. However, the response varied among plant parts; in leaves and culms weights were slightly increased or stable; cob weights decreased; and other ear parts of dent corn also decreased by high temperature. Photosynthetic activity was not affected by the treatments. The (13)C export rate from an ear leaf was decreased by the high temperature treatment. The amount of (13)C partitioning to the ears decreased more than to other plant parts by the high temperature. Within the ear decreases were greatest in the cob than the shank within an ear. Sugar concentrations in both hemicellulose and cellulose fractions of cobs in sweet corn were decreased by high temperature, and the hemicellulose fraction in the shank also decreased. In dent corn there was no reduction of sugar concentration except in the in cellulose fraction, suggesting that synthesis of cell-wall components is impaired by high temperatures. The high temperature treatment promoted the growth of vegetative plant parts but reduced ear expansion, particularly suppression of cob extensibility by impairing hemicellulose and cellulose synthesis through reduction of photosynthate supply. Therefore, plant biomass production was enhanced and grain yield reduced by the high temperature treatment due to effects on sink activity rather than source activity. Heat resistant ear development can be targeted for genetic improvement.

Resveratrol enhances the cytotoxic profile of docetaxel and doxorubicin in solid tumour cell lines in vitro

Objectives:  Resveratrol, with its robust antioxidant activity, has frequently been suggested as potentially having activity in cancer prevention and some recent reports have indicated that it has cancer treatment potential for several types of neoplasia. It has been found to block p‐glycoprotein and to protect against several chemotherapeutic agents’ side effects. In this study, we assessed interactive characteristics of resveratrol with docetaxel and doxorubicin and further investigated molecular bases of this interaction in cells of three different solid tumour lines (MCF‐7, HeLa and HepG2).

Willow Leaves' Extracts Contain Anti-Tumor Agents Effective against Three Cell Types

Many higher plants contain novel metabolites with antimicrobial, antifungal and antiviral properties. However, in the developed world almost all clinically used chemotherapeutics have been produced by in vitro chemical synthesis. Exceptions, like taxol and vincristine, were structurally complex metabolites that were difficult to synthesize in vitro. Many non-natural, synthetic drugs cause severe side effects that were not acceptable except as treatments of last resort for terminal diseases such as cancer. The metabolites discovered in medicinal plants may avoid the side effect of synthetic drugs, because they must accumulate within living cells. The aim here was to test an aqueous extract from the young developing leaves of willow (Salix safsaf, Salicaceae) trees for activity against human carcinoma cells in vivo and in vitro. In vivo Ehrlich Ascites Carcinoma Cells (EACC) were injected into the intraperitoneal cavity of mice. The willow extract was fed via stomach tube. The (EACC) derived tumor growth was reduced by the willow extract and death was delayed (for 35 days). In vitro the willow extract could kill the majority (75%–80%) of abnormal cells among primary cells harvested from seven patients with acute lymphoblastic leukemia (ALL) and 13 with AML (acute myeloid leukemia). DNA fragmentation patterns within treated cells inferred targeted cell death by apoptosis had occurred. The metabolites within the willow extract may act as tumor inhibitors that promote apoptosis, cause DNA damage, and affect cell membranes and/or denature proteins.

Evaluation of amino acid content and nutritional quality of transgenic soybean seeds with high-level tryptophan accumulation

Anthranilate synthase (AS) is a key regulatory enzyme in tryptophan (Trp) biosynthesis and is subject to feedback inhibition by Trp. The gene encoding a mutated feedback-resistant α subunit of rice AS (OASA1D) under the control of either a soybean glycinin gene promoter or the 35S promoter of cauliflower mosaic virus for seed-specific or constitutive expression, respectively, was introduced into soybean [Glycine max (L.) Merrill] by particle bombardment. A total of seven different transgenic lines that showed markedly increased accumulation of free Trp in their seeds were developed. The overproduction of free Trp was stably inherited in subsequent generations without any apparent detrimental effect on plant growth or reproduction. The total Trp content of transgenic seeds was also about twice that of nontransgenic seeds, whereas the amount of protein-bound Trp was not substantially affected by OASA1D expression. In spite of the marked increase in free Trp content, metabolic profiling by high-performance liquid chromatography coupled with mass spectrometry revealed little change in the amounts of other aromatic compounds in the transgenic seeds. We developed a rapid and feasible system based on farmed rainbow trout to evaluate the nutritional quality of a limited quantity of transgenic soybean seeds. Supplementation of fish food with OASA1D transgenic soybean seeds or with nontransgenic seeds plus crystalline Trp increased the growth rate of the farmed fish. These results indicate transformation with OASA1D is a reliable approach to improve the nutritional quality of soybean (or of other grain legumes) for human and animal food.

Isolation of soybean plants with stable transgene expression by visual selection based on green fluorescent protein

Particle bombardment is a common platform for soybean transformation but tends to cause transgene silencing due to the integration of rearranged or multiple copies of transgenes. We now describe the isolation of a total of 44 independent transgenic soybean plants after transformation by particle bombardment with one of two gene constructs, pHV and pHVS. Both constructs contain the hygromycin phosphotransferase gene (hpt) as a selectable marker and a modified glycinin gene (V3-1) for evaluation of homology-dependent silencing of endogenous glycinin genes; pHVS also contains sGFP(S65T), which encodes a modified form of green fluorescent protein (GFP), as a reporter gene in the flanking region of V3-1. Fluorescence microscopy revealed that the leaves of 8 of the 25 independent transgenic plants obtained with pHVS expressed GFP; most of these GFP-positive plants also contained V3-1 mRNA and an increased glycinin content in their seeds, and they exhibited simple banding patterns on Southern blots that were indicative of a low copy number of each of the three transgenes. In contrast, most of the transgenic plants obtained with pHVS that did not express GFP, as well as most of those obtained with pHV, lacked endogenous glycinin in their seeds and exhibited more complex patterns of transgene integration. The use of a reporter gene such as sGFP(S65T) in addition to an antibiotic resistance gene may thus help to reduce the problem of gene silencing associated with direct DNA transformation systems and facilitate the recovery of transgenic plants that stably express the gene of interest.

Modulatory role of lipoic acid on lipopolysaccharide-induced oxidative stress in adult rat Sertoli cells in vitro

Inflammatory reactions to microbial infections may cause male infertility. The mechanisms of inhibition of spermatogenesis can be studied in vitro using rat Sertoli cells. Bacterial lipopolysaccharides (LPS) induce acute inflammations. So LPS treated Sertoli cells can be used to test for new therapeutic compounds. The present study aimed to investigate the protective efficacy of dl-alpha-lipoic acid (LA) on lipopolysaccharide (LPS)-induced oxidative stress in adult rat Sertoli cells. Sertoli cells were divided into 4 groups. Group I served as a control incubated with water (vehicle). Groups II and IV were incubated with 100 microM LA for 24h before incubating Groups III and IV with 50 microg/ml lipopolysaccharide (LPS) for 12h. In Group III cells (LPS-treated, no LA) the lactate concentration was decreased whereas hydrogen peroxide production and lipid peroxidation were significantly increased. Moreover, the activities of antioxidant enzymes such as superoxide dismutase, glutathione peroxidase, catalase, glutathione-S-transferase, glutathione reductase were reduced. The concentrations of antioxidant molecules such as reduced glutathione and vitamin C were significantly decreased. The activities of enzymes normally elevated in Sertoli cells, gamma-glutamyl transpeptidase and beta-glucuronidase, were significantly decreased. Treatment with LA (100 microM) for 24h before LPS-treatment (Group IV), prevented these changes in enzyme activities and metabolite concentrations. Therefore, LA may have a cyto-protective role during LPS-induced inflammation in adult rat Sertoli cells.