Hesham Shafik | Natinal research center (original) (raw)
Papers by Hesham Shafik
Annales De Limnologie-international Journal of Limnology, Dec 1, 1997
The growth and cell composition of C. meneghiniana in P-, Nor Si-Mmited continuous cultures under... more The growth and cell composition of C. meneghiniana in P-, Nor Si-Mmited continuous cultures under different dilutions are discussed. Carbon, nitrogen and phosphorus content per cell or per unit cell volume increased with growth rate in all chemostats. Maximum growth rate depends on the type of limiting nutrient. The maximum growth rates are. 1.65 ± 0.04,0.73 ± 0.07 and 0.95 ± 0.08 d" 1 for P-, N-and Si-limited cultures respectively. These values are close to those calculated by Droop, Caperon, Goldman and Monod models. The concentrations of N and P in the river Danube are much higher than the requirements for growth and uptake of C. meneghiniana. This indicates that neither P nor N are limiting to the growth of C. meneghiniana in natural habitat. Croissance de Cyclotella meneghiniana Kutz. II. Croissance et composition cellulaire à différents taux de croissance en fonction de nutriments limitants Mots clés : Cyclotella meneghiniana, croissance, composition cellulaire, nutriment limitant, culture en continu. La croissance et la composition cellulaire de C. meneghiniana soumis à des concentrations limitantes en P, N et Si en culture continue à des taux de dilution différents sont discutés. Le contenu cellulaire en carbone, azote et phosphore par cellule ou par unité de volume augmente avec le taux de croissance dans toutes les conditions précitées. Le taux maximum de croissance dépend du type de nutriment limitant. Ces valeurs sont très proches de celles calculées à partir des modèles de Droop, Caperon, Goldman et Monod. Dans le Danube, les concentrations en N et P sont beaucoup plus élevées que les besoins pour la croissance et l'assimilation de C. meneghiniana. Cela indique que ni N ni P ne sont limitants pour la croissance de C. meneghiniana en milieu naturel.
Journal of Radioanalytical and Nuclear Chemistry, Jul 25, 2023
The aim of study was the production of polyclonal antibody of erythropoietin hormone (Anti-EPO) t... more The aim of study was the production of polyclonal antibody of erythropoietin hormone (Anti-EPO) to determine EPO in human serum by liquid-phase radioimmunoassay (RIA). Production of anti-EPO was performed by immunizing Balb/C mice with EPO antigen using primary immunization and four booster doses. EPO tracer (125 I-EPO) was prepared using Chloramine-T method. Additionally, EPO standards were mad. Furthermore, the assay was optimized and validated in additional studies. In conclusion, the elaborated EPO-RIA system exhibits a simple, accurate, specific and sensitive method for determining EPO concentration in human serum and might be suitable for clinical diagnosis of myeloproliferative diseases.
Journal of Radioanalytical and Nuclear Chemistry, 2014
Various adjuvants have been used to enhance the immune response against specific antigens. So the... more Various adjuvants have been used to enhance the immune response against specific antigens. So the objective of this work describes the immune stimulating activity of layered double hydroxide (LDH) particles incorporate with mineral oil as a new formulation of adjuvant as compared to known Freund's adjuvant for production of alpha-fetoprotein polyclonal antibody (anti-AFP) for estimation of alpha fetoprotein (AFP) in human serum by radioimmunoassay technique. In this concern, the study comprised two groups of white New Zealand rabbits, 2-2.5 kg body weight and each group comprised three rabbits. The first group vaccinated with AFP antigen emulsified with Freund's adjuvant and the second group vaccinated with AFP antigen emulsified with LDH formulation. The obtained data show that the highest displacement using LDH adjuvant reached (74.2, 61.7 and 66.5 %) while the corresponding values with Freund's adjuvant recorded (64.8, 60.3 and 54.6 %) which indicates that the use of LDH adjuvant as a cellular vehicle is a more suitable choice. Also, the preparation of AFP tracer using lactoperoxidase oxidation method and its purification using gel chromatography on PD-10 column were carried out. Different factors affecting the optimization of the assay process were studied. Validation testes of the assay were carried out. The reproducibility as measured by the intraand inter-assay variations is satisfactory. The recovery and dilution testes indicated accurate calibration and appropriate matrix. The present technique agreed well with the currently used commercial kit (Siemens, IRMA kit). In conclusion, the liquid phase double antibody RIA technique proved to be sensitive, specific, precis and accurate for routine laboratory use.
Egyptian journal of phycology, Dec 30, 2012
Since the rediscovery of picophytoplankton (PPP) in 1978-1979, the information and method of stud... more Since the rediscovery of picophytoplankton (PPP) in 1978-1979, the information and method of studying of these living organisms have improving quickly. This review collects the most important methods for studding these tiny planktonic which play a significant role in all aquatic ecosystems. In addition to, give an over view on the results obtained on the contributions, abundant and role of these groups in different habitats and they correlation with physical, chemical and environmental parameters, such as temperature, light intensity and quality, salinity, pH, trophic state, and grazing. The development of gene sequencing, the molecular approach and phylogenetic analysis give an advanced direction to taxonomy of PPP and their relation and interactions to environmental factor, therefore the review shows the new results of this topic.
Alfarama Journal of basic & applied sciences (Online), Apr 12, 2020
This research was carried out to screen and characterize the rmophilic bacteria that have the abi... more This research was carried out to screen and characterize the rmophilic bacteria that have the ability to produce cellulase enzyme. Bacterial strains were isolated from the sediment samples collected from Ras-Sedr's hot spring located in Ras-Sedr, Egypt. For cellulolytic activity testing, Carboxymethylcellulose (CMC) agar was used as growth medium. Seven bacterial isolates showed variable zones of CMC clearance. Evaluation of cellulase enzyme thermal activity was carried out at varying temperatures from 35°C to 85°C and the impact of pH on cellulase activity was evaluated at different pH levels of 5-9. Molecular identification for the isolates also conducted based on 16S rRNA gene sequencing. At 55°C and pH 7, all the seven bacterial isolates showed their optimum growth conditions. Strains were gram positive, have rod shape cells, spore forming and motile with the ability to produce thermostable cellulase. The results of the phylogenetic analysis reveal a high degree of sequence similarity between the isolated bacteria involved in this research and Geobacillus sp. These thermophiles have the ability to produce useful thermostable cellulase enzyme of industrial significance, which in turn indicates that Ras-Sedr's hot spring considered a prospective source of economically significant microorganisms which needs more studies through further researches.
Saudi Journal of Biological Sciences, May 1, 2020
This work aims to outline the dynamics of trophic links between the three main microbial componen... more This work aims to outline the dynamics of trophic links between the three main microbial components (bacteria, nanoflagellates, and ciliates) of the Farasan Archipelago in order to establish a baseline for future research in this area. The Farasan Archipelago lies along the southwestern coast of the Saudi Arabia, southern Red Sea between 16°20 0-17°10 0 N and 41°30 0-42°30 0 E and had been declared as marine and terrestrial reserve by the year 1996. Three different sites were chosen for this study, with each site visited bimonthly for 18 months from September 2016 to February 2018. Bacteria, nanoflagellates and ciliates were enumerated in order to explore the complex interactions between the main microbial categories in sea waters of the Farasan Archipelago. High abundances were recorded during the present study for bacteria (8.7 Â 10 6 bacteria ml À1), nanoflagellates (3.7 Â 10 4 TNAN ml À1) and ciliates (40.4 ciliates ml À1). The paper discusses the various potential pathways controlling the complex interactions between these microbial groups in this part of the southern Red Sea. It is concluded that a linear trophic chain consisting of bacteria; heterotrophic nanoflagellates; filter feeding ciliates is a major route by which the production of bacteria is transferred to the higher consuming levels, thereby confirming the high importance of t bottom-up control (food supply), alongside top-down control (predation) in regulating bacterial abundances in the Farasan Archipelago. During the present investigation, each nanoflagellate ingested between 11 and 87 bacteria in one hour, while each ciliate consumed between 20 and 185 nanoflagellates every hour. These calculated grazing rates of protistan eukaryotes confirmed the role of heterotrophic nanoflagellates as the main consumers of bacteria, and the role of ciliates as the major control for the heterotrophic nanoflagellate population dynamics, and thus the top predators within the microbial plankton assemblage in the Farasan Archipelago.
International Review of Hydrobiology, 1998
Aliquots of a water sample taken from the mesotrophic basin of Lake Balaton in August were incuba... more Aliquots of a water sample taken from the mesotrophic basin of Lake Balaton in August were incubated in three identical (2 liter) chemostats. Nutrients (35 pg POI-P. I-' week-' and 350 pg N03-N. I-' week-') were added by weekly pulses to the first culture and by continuous supply to the other two. The third culture was enriched continuously with Na-acetate (5 mg. I-' week-'). Pulsed nutrient supply resulted in permanent coexistence of three algal species (Mougeotia sp., Syedra acus v. radians and Lyngbya limnetica) while the continuous supply (second culture) led to the predominance of Lyngbya lirnnetica. The Na-acetate addition experiment showed, that in the absence of carbon limitation, picophytoplankton were able to compete successfully with bacteria. The results indicate that indigenous phytoplankton can only thrive when bacterial growth is limited by carbon.
Saudi Journal of Biological Sciences, Jul 1, 2014
Mutation research, Jun 1, 1980
Radiochimica Acta, Jun 15, 2015
In heterogeneous conditions, water soluble Chitosan-Vitamin C Complex (CSVC) is successfully synt... more In heterogeneous conditions, water soluble Chitosan-Vitamin C Complex (CSVC) is successfully synthesized via the ionic interaction between-degraded CS and VC. Chitosan (CS) of low molecular weight (MW) is prepared using-irradiation method. The coupling of CS and vitamin C (VC) is carried out by the chemical treatment of VC with the-degraded CS. The formation of CSVC complex instead of physical mixture is confirmed by FT-IR and UV spectrometry. Characterization by transmission electron microscope (TEM) and dynamic light scattering (DLS) shows the formation of a nanostructure in 40 nm range. The preparation of labeled CSVC was performed using chloramines-T oxidation method. The labeling feasibility of CSVC nanostructure by Iodine-125 (125 I) is investigated. The optimized conditions of labeling are thought to be 50 μg of oxidizing agent, pH 3, and one minute reaction time. The Biodistribution activity of 125 I radiolabeled CSVC nanostructure (125 I-CSVC) is examined on a group of different ascites tumor bearing mice. Calculation of the biodistribution percentages shows that the tumor, liver, and kidney are the targeting organs of 125 I-CSVC nanostructure.
Archiv für Hydrobiologie, Dec 3, 2001
The cyanoprokaryote Cylindrospermopsis raciborskii bloomed many times in Lake Balaton. Some physi... more The cyanoprokaryote Cylindrospermopsis raciborskii bloomed many times in Lake Balaton. Some physical parameters and nitrogen forms controlling the growth of C raciborskii were investigated in batch and flow-through cultures. The optimum light intensity was 121 ± 13 μmol m -2 s -1 , while light requirement for growth was low (I k was between 22 and 26 μmol m -2 s -1 ). The optimum temperature was 30 °C, and the maximum growth rate was depending on the nitrogen source. The maximum growth rate lies between 0.84 and 0.88 d -1 when the atmospheric nitrogen (N 2 ) was the sole nitrogen source. When the NH 4 -N was the nitrogen source, the maximum growth rate reached a value of 1.6 d -1 . C. raciborskii has fixed the atmospheric nitrogen even if other nitrogen source as NO 3 -N was available. The strategy of growth may depend on: 1 - nitrogen fixation, when other algae were nitrogen limited; 2 - fast PO 4 -P uptake even if very low concentration is available; and 3 - it has low light requirement, and high temperature.
Hydrobiologia, 2003
Morphological characteristics of Cylindrospermopsis raciborskii were investigated in batch cultur... more Morphological characteristics of Cylindrospermopsis raciborskii were investigated in batch culture under Pstarvation and in continuous cultures at two growth rates with different N forms. The species displayed an enormous morphological variability under controlled condition. In the P-starved batch culture very short and extreme morphology trichomes with conical or drop-shape heterocytes were formed. In continuous culture extremely long, twisted filaments were found near the maximum growth rate. Rarely, C. raciborskii formed intercalary heterocytes.
Freshwater Biology, Dec 1, 2005
1. This study introduces delayed fluorescence (DF) excitation spectroscopy as an on-line tool for... more 1. This study introduces delayed fluorescence (DF) excitation spectroscopy as an on-line tool for in situ monitoring of the composition and biomass of various colour classes of phytoplankton when they are photosynthetically active (cyanobacteria, chlorophytes, chromophytes and cryptophytes). The DF data are validated by comparison with those from conventional methods (weekly microscopic counts and the measurement of chlorophyll concentration). 2. The composition of phytoplankton as assessed by DF agreed reasonably well with the results from microscopic counts, particularly when differences in chlorophyll-specific DF integrals of the various colour classes were taken into account. 3. Integrals of DF spectra were converted into concentration of chlorophyll a using empirical factors derived from field data. The value of the conversion factor was nearly twice as high when the relative abundance of cyanobacteria was low (<15%) than when it was high. The converted DF-chl time series agreed well with chlorophyll measurements particularly when blooms were developing. As the DF method is inherently free of the interference caused by pigment degradation products, the discrepancy between the two data sets increased during the collapse of blooms and when sediment resuspension was intense. 4. Fourier spectrum analysis of the time series of DF-chl indicated that samples must be taken, at a minimum, every 2-3 days to capture the dynamics of phytoplankton. As a consequence, the dynamics of various algal blooms, including their timing, duration and net growth rate, could be estimated with greater confidence than by using conventional methods alone. 5. On-line DF spectroscopy is an advanced technique for monitoring daily the biomass and composition of the photosynthetically active phytoplankton in aquatic environments, including turbid shallow lakes. At present, the detection limit is around 1 mg DF-chl a m)3 in terms of total biomass but confidence in estimates of phytoplankton composition declines sharply below about 5 mg chl a m)3. 6. On-line DF spectroscopy represents a promising approach for monitoring phytoplankton. It will be useful in water management where it can act as an early-warning system of declines in water quality. In basic ecological research it can supplement
Turkish Journal of Fisheries and Aquatic Sciences, Jun 1, 2014
The Bitter Lake is the central and most important water body of the Suez Canal as it contains 85%... more The Bitter Lake is the central and most important water body of the Suez Canal as it contains 85% of the water of the canal system. This study reports the microplankton found occurring in the surface water of the Bitter Lake at monthly intervals from November 2008 until November 2009. A total of 130 taxa were identified, among which 67 taxa were of Bacillariophyceae, 15 Dinophyceae, 11 Chlorophyceae, 11 Cyanophyceae, 1 Euglenophyceae, 18 Tintinnidae, 4 Foraminiferidae, as well as 3 of Rotifera. Species diversity, numerical abundances and dynamics were analyzed for each taxon at three sites inside the Bitter Lake. At each of these sites Bacillariophyceae were predominant in the standing crop forming 67.2% of the total microplankton community with an average of 11,594 ind. L-1. The Dinophyceae occupied the second rank constituting about 16.5% of the total microplankton. Increase of microplankton abundance started in spring with maximum values being attained in late summer and early autumn (August), with an average of 37,498 ind. L-1 , while January was characterized by the lowest density (9,251 ind. L-1). Relatively higher diversity values were recorded at the northern part of the lake and a progressive decline in diversity was observed southward. Nutrient concentrations in the lake waters were very low, with silicate varying between 0.52-1.34 µM, phosphate between 0.14 and 0.55 µM and nitrate between 0.82-3.16 µmol L-1. Moreover, chlorophyll a fluctuated between 0.4 and 0.89 µg L-1. Data from microplankton analyses, nutrient (P) and chlorophyll a concentrations and transparency measurements were used to assess the ecosystem health of the Bitter Lake according to OECD, Canadian, and Quebec classification criteria, and it is concluded that the Bitter Lake be classified as an ultraoligotrophic lake.
Acta Biologica Hungarica, Mar 1, 2003
The freshwater cyanoprokaryote Cylindrospermopsis raciborskii has become increasingly prevalent i... more The freshwater cyanoprokaryote Cylindrospermopsis raciborskii has become increasingly prevalent in tropical and temperate water bodies worldwide. The morphological characteristics of this species were investigated under different growth rates in continuous cultures (at steady state) and in batch (phosphorus starved) cultures with different mineral nitrogen forms. The species displays an enormous morphological variability under controlled condition. The occurrence of extreme long twisted filaments was found near the maximum growth rate and under high ammonium concentration. Rarely the heterocytes of Cylindrospermopsis raciborskii arise intercalarly between two neighbouring cells (i.e. intercalary heterocytes were found). The morphological features are highly effected by environmental conditions and nutrient availability. Under P-starvation extreme morphology appeared. The specifications of C. africana and C. cuspis overlap with that of C. raciborskii accordingly this is not clear characteristic feature to distinguish species. A pure culture of a pro-or eukaryote alga growing in continuous cultures is a good method for giving a suitable overview on all morphological possibilities of a tested organism.
Annales De Limnologie-international Journal of Limnology, Sep 1, 1997
A strain of Cyclotella meneghiniana was isolated from the River Danube. The optimum irradiance an... more A strain of Cyclotella meneghiniana was isolated from the River Danube. The optimum irradiance and temperature for growth were determined in batch cultures. The optimum temperature for growth was 25 °C. The estimated saturated irradiance was near 125 uE m 2 s 1. The calculated I k for growth and photosynthesis were 30 ± 3 and 44 ± 6 uE nr 2 s 1 respectively. A continuous culture technique was used to test the growth and cell composition at the transition state between batch, nutrient sufficiency, and a low rate of nutrient supply. Algal response was characterized by high intracellular N and C with negative growth rate. At a low dilution rate (0.06 d 1), the continuous culture theory was not followed. This critical rate is characterized by low chlorophyll-a content per cell and may depend on the mode of nutrition.
Hydrobiologia, 2003
Ammonium and nitrate uptake and N 2-fixation of the heterocystous cyanoprokaryote Cylindrospermop... more Ammonium and nitrate uptake and N 2-fixation of the heterocystous cyanoprokaryote Cylindrospermopsis raciborskii was examined in continuous cultures under different nitrogen concentrations and dilution rates using the 15 N technique. It was found that at luxury phosphorus supply (5 mg PO 4-P l −1) the biomass was similar in all cultures irrespective of the amount and portioning (continuous or pulsed) of available nitrogen forms. The added ammonium and nitrate was fully taken up by C. raciborskii and the remaining nitrogen demand was met by N 2fixation. Different ammonium concentrations (300, 750, 1500 and 3000 µg 15 N l −1) added at the same dilution rate did not affect the growth of C. raciborskii. In the culture supplied with pulsed ammonium, N 2-fixation was detected prior to ammonium addition only. After the ammonium pulse, the N 2-fixation continued for a while then decreased and stopped. In addition, the inflowing ammonium was fully taken up by the organism. The rate of nitrogen fixation reached its original level after 8-24 hours, depending on the dilution rate. It can be suggested that the nitrogen fixation system stopped and was then activated again depending on the nitrogen content of the cells.
African Journal of Aquatic Science, Aug 27, 2010
... Menlo Park, California: Benjamin Cummings. Dewedar A, Bahgat M, Shabana EE. 2009. ... Journal... more ... Menlo Park, California: Benjamin Cummings. Dewedar A, Bahgat M, Shabana EE. 2009. ... Journal of Applied Bacteriology 140: 163188. El-Bana M, Khedr AH, van Hecke P, Bogaert J. 2002. Vegetation composition of a threatened hypersaline lake (Lake Bardawil), North Sinai. ...
Alfarama Journal of basic & applied sciences (Online), Jul 1, 2021
Navicula arenaria Donkin 1861 is a marine microalga belongs to class of bacillariophycea. Recentl... more Navicula arenaria Donkin 1861 is a marine microalga belongs to class of bacillariophycea. Recently, microalgae and their products are used as biological control of diseases caused by phytopathogenic fungi. This is considered environmentally ecofriendly method to overcome the plant damage caused by soil borne pathogenic fungi and thereby economic loss. Therefore, this study aimed to investigate in vitro the antifungal activity of N. arenaria isolate PS 31 extracellular and intracellular metabolites against two taxa of soil borne phytopathogenic fungi; Macrophomina phaseolina and Fusarium oxysporum. N. arenaria PS 31 hexane extract was the most effective extract on growth inhibition of both phytopathogenic fungi. There is no significant difference between miconazole and N. arenaria hexane extract of 5.6 mg/ml on growth inhibition of F. oxysporum. The inhibitory effect of hexane extract at 5.6, 4.2 and 2.8 mg/ml and ethyl acetate extract at 35% (v/v) was higher than controls. Ethyl acetate extract was effective on growth inhibition of M. phaseolina (29.67%). GC-MS analysis of N. arenaria hexane fraction revealed the presence of potent antifungal compounds such as Phenol, 2,2'-methylenebis[6-(1,1-dimethylethyl)-4methyl-, din -octyl phthalate, cholestane-3,5-diol, 5-acetate,(3.beta.,5.alpha.), Cholestan-3ol,(3.beta.,5.beta.)-and beta.-Sitosterol. These results suggest that N. arenaria hexane extract can be used in biological control of plant diseases caused by M. phaseolina and F. oxysporum.
Annales De Limnologie-international Journal of Limnology, Dec 1, 1997
The growth and cell composition of C. meneghiniana in P-, Nor Si-Mmited continuous cultures under... more The growth and cell composition of C. meneghiniana in P-, Nor Si-Mmited continuous cultures under different dilutions are discussed. Carbon, nitrogen and phosphorus content per cell or per unit cell volume increased with growth rate in all chemostats. Maximum growth rate depends on the type of limiting nutrient. The maximum growth rates are. 1.65 ± 0.04,0.73 ± 0.07 and 0.95 ± 0.08 d" 1 for P-, N-and Si-limited cultures respectively. These values are close to those calculated by Droop, Caperon, Goldman and Monod models. The concentrations of N and P in the river Danube are much higher than the requirements for growth and uptake of C. meneghiniana. This indicates that neither P nor N are limiting to the growth of C. meneghiniana in natural habitat. Croissance de Cyclotella meneghiniana Kutz. II. Croissance et composition cellulaire à différents taux de croissance en fonction de nutriments limitants Mots clés : Cyclotella meneghiniana, croissance, composition cellulaire, nutriment limitant, culture en continu. La croissance et la composition cellulaire de C. meneghiniana soumis à des concentrations limitantes en P, N et Si en culture continue à des taux de dilution différents sont discutés. Le contenu cellulaire en carbone, azote et phosphore par cellule ou par unité de volume augmente avec le taux de croissance dans toutes les conditions précitées. Le taux maximum de croissance dépend du type de nutriment limitant. Ces valeurs sont très proches de celles calculées à partir des modèles de Droop, Caperon, Goldman et Monod. Dans le Danube, les concentrations en N et P sont beaucoup plus élevées que les besoins pour la croissance et l'assimilation de C. meneghiniana. Cela indique que ni N ni P ne sont limitants pour la croissance de C. meneghiniana en milieu naturel.
Journal of Radioanalytical and Nuclear Chemistry, Jul 25, 2023
The aim of study was the production of polyclonal antibody of erythropoietin hormone (Anti-EPO) t... more The aim of study was the production of polyclonal antibody of erythropoietin hormone (Anti-EPO) to determine EPO in human serum by liquid-phase radioimmunoassay (RIA). Production of anti-EPO was performed by immunizing Balb/C mice with EPO antigen using primary immunization and four booster doses. EPO tracer (125 I-EPO) was prepared using Chloramine-T method. Additionally, EPO standards were mad. Furthermore, the assay was optimized and validated in additional studies. In conclusion, the elaborated EPO-RIA system exhibits a simple, accurate, specific and sensitive method for determining EPO concentration in human serum and might be suitable for clinical diagnosis of myeloproliferative diseases.
Journal of Radioanalytical and Nuclear Chemistry, 2014
Various adjuvants have been used to enhance the immune response against specific antigens. So the... more Various adjuvants have been used to enhance the immune response against specific antigens. So the objective of this work describes the immune stimulating activity of layered double hydroxide (LDH) particles incorporate with mineral oil as a new formulation of adjuvant as compared to known Freund's adjuvant for production of alpha-fetoprotein polyclonal antibody (anti-AFP) for estimation of alpha fetoprotein (AFP) in human serum by radioimmunoassay technique. In this concern, the study comprised two groups of white New Zealand rabbits, 2-2.5 kg body weight and each group comprised three rabbits. The first group vaccinated with AFP antigen emulsified with Freund's adjuvant and the second group vaccinated with AFP antigen emulsified with LDH formulation. The obtained data show that the highest displacement using LDH adjuvant reached (74.2, 61.7 and 66.5 %) while the corresponding values with Freund's adjuvant recorded (64.8, 60.3 and 54.6 %) which indicates that the use of LDH adjuvant as a cellular vehicle is a more suitable choice. Also, the preparation of AFP tracer using lactoperoxidase oxidation method and its purification using gel chromatography on PD-10 column were carried out. Different factors affecting the optimization of the assay process were studied. Validation testes of the assay were carried out. The reproducibility as measured by the intraand inter-assay variations is satisfactory. The recovery and dilution testes indicated accurate calibration and appropriate matrix. The present technique agreed well with the currently used commercial kit (Siemens, IRMA kit). In conclusion, the liquid phase double antibody RIA technique proved to be sensitive, specific, precis and accurate for routine laboratory use.
Egyptian journal of phycology, Dec 30, 2012
Since the rediscovery of picophytoplankton (PPP) in 1978-1979, the information and method of stud... more Since the rediscovery of picophytoplankton (PPP) in 1978-1979, the information and method of studying of these living organisms have improving quickly. This review collects the most important methods for studding these tiny planktonic which play a significant role in all aquatic ecosystems. In addition to, give an over view on the results obtained on the contributions, abundant and role of these groups in different habitats and they correlation with physical, chemical and environmental parameters, such as temperature, light intensity and quality, salinity, pH, trophic state, and grazing. The development of gene sequencing, the molecular approach and phylogenetic analysis give an advanced direction to taxonomy of PPP and their relation and interactions to environmental factor, therefore the review shows the new results of this topic.
Alfarama Journal of basic & applied sciences (Online), Apr 12, 2020
This research was carried out to screen and characterize the rmophilic bacteria that have the abi... more This research was carried out to screen and characterize the rmophilic bacteria that have the ability to produce cellulase enzyme. Bacterial strains were isolated from the sediment samples collected from Ras-Sedr's hot spring located in Ras-Sedr, Egypt. For cellulolytic activity testing, Carboxymethylcellulose (CMC) agar was used as growth medium. Seven bacterial isolates showed variable zones of CMC clearance. Evaluation of cellulase enzyme thermal activity was carried out at varying temperatures from 35°C to 85°C and the impact of pH on cellulase activity was evaluated at different pH levels of 5-9. Molecular identification for the isolates also conducted based on 16S rRNA gene sequencing. At 55°C and pH 7, all the seven bacterial isolates showed their optimum growth conditions. Strains were gram positive, have rod shape cells, spore forming and motile with the ability to produce thermostable cellulase. The results of the phylogenetic analysis reveal a high degree of sequence similarity between the isolated bacteria involved in this research and Geobacillus sp. These thermophiles have the ability to produce useful thermostable cellulase enzyme of industrial significance, which in turn indicates that Ras-Sedr's hot spring considered a prospective source of economically significant microorganisms which needs more studies through further researches.
Saudi Journal of Biological Sciences, May 1, 2020
This work aims to outline the dynamics of trophic links between the three main microbial componen... more This work aims to outline the dynamics of trophic links between the three main microbial components (bacteria, nanoflagellates, and ciliates) of the Farasan Archipelago in order to establish a baseline for future research in this area. The Farasan Archipelago lies along the southwestern coast of the Saudi Arabia, southern Red Sea between 16°20 0-17°10 0 N and 41°30 0-42°30 0 E and had been declared as marine and terrestrial reserve by the year 1996. Three different sites were chosen for this study, with each site visited bimonthly for 18 months from September 2016 to February 2018. Bacteria, nanoflagellates and ciliates were enumerated in order to explore the complex interactions between the main microbial categories in sea waters of the Farasan Archipelago. High abundances were recorded during the present study for bacteria (8.7 Â 10 6 bacteria ml À1), nanoflagellates (3.7 Â 10 4 TNAN ml À1) and ciliates (40.4 ciliates ml À1). The paper discusses the various potential pathways controlling the complex interactions between these microbial groups in this part of the southern Red Sea. It is concluded that a linear trophic chain consisting of bacteria; heterotrophic nanoflagellates; filter feeding ciliates is a major route by which the production of bacteria is transferred to the higher consuming levels, thereby confirming the high importance of t bottom-up control (food supply), alongside top-down control (predation) in regulating bacterial abundances in the Farasan Archipelago. During the present investigation, each nanoflagellate ingested between 11 and 87 bacteria in one hour, while each ciliate consumed between 20 and 185 nanoflagellates every hour. These calculated grazing rates of protistan eukaryotes confirmed the role of heterotrophic nanoflagellates as the main consumers of bacteria, and the role of ciliates as the major control for the heterotrophic nanoflagellate population dynamics, and thus the top predators within the microbial plankton assemblage in the Farasan Archipelago.
International Review of Hydrobiology, 1998
Aliquots of a water sample taken from the mesotrophic basin of Lake Balaton in August were incuba... more Aliquots of a water sample taken from the mesotrophic basin of Lake Balaton in August were incubated in three identical (2 liter) chemostats. Nutrients (35 pg POI-P. I-' week-' and 350 pg N03-N. I-' week-') were added by weekly pulses to the first culture and by continuous supply to the other two. The third culture was enriched continuously with Na-acetate (5 mg. I-' week-'). Pulsed nutrient supply resulted in permanent coexistence of three algal species (Mougeotia sp., Syedra acus v. radians and Lyngbya limnetica) while the continuous supply (second culture) led to the predominance of Lyngbya lirnnetica. The Na-acetate addition experiment showed, that in the absence of carbon limitation, picophytoplankton were able to compete successfully with bacteria. The results indicate that indigenous phytoplankton can only thrive when bacterial growth is limited by carbon.
Saudi Journal of Biological Sciences, Jul 1, 2014
Mutation research, Jun 1, 1980
Radiochimica Acta, Jun 15, 2015
In heterogeneous conditions, water soluble Chitosan-Vitamin C Complex (CSVC) is successfully synt... more In heterogeneous conditions, water soluble Chitosan-Vitamin C Complex (CSVC) is successfully synthesized via the ionic interaction between-degraded CS and VC. Chitosan (CS) of low molecular weight (MW) is prepared using-irradiation method. The coupling of CS and vitamin C (VC) is carried out by the chemical treatment of VC with the-degraded CS. The formation of CSVC complex instead of physical mixture is confirmed by FT-IR and UV spectrometry. Characterization by transmission electron microscope (TEM) and dynamic light scattering (DLS) shows the formation of a nanostructure in 40 nm range. The preparation of labeled CSVC was performed using chloramines-T oxidation method. The labeling feasibility of CSVC nanostructure by Iodine-125 (125 I) is investigated. The optimized conditions of labeling are thought to be 50 μg of oxidizing agent, pH 3, and one minute reaction time. The Biodistribution activity of 125 I radiolabeled CSVC nanostructure (125 I-CSVC) is examined on a group of different ascites tumor bearing mice. Calculation of the biodistribution percentages shows that the tumor, liver, and kidney are the targeting organs of 125 I-CSVC nanostructure.
Archiv für Hydrobiologie, Dec 3, 2001
The cyanoprokaryote Cylindrospermopsis raciborskii bloomed many times in Lake Balaton. Some physi... more The cyanoprokaryote Cylindrospermopsis raciborskii bloomed many times in Lake Balaton. Some physical parameters and nitrogen forms controlling the growth of C raciborskii were investigated in batch and flow-through cultures. The optimum light intensity was 121 ± 13 μmol m -2 s -1 , while light requirement for growth was low (I k was between 22 and 26 μmol m -2 s -1 ). The optimum temperature was 30 °C, and the maximum growth rate was depending on the nitrogen source. The maximum growth rate lies between 0.84 and 0.88 d -1 when the atmospheric nitrogen (N 2 ) was the sole nitrogen source. When the NH 4 -N was the nitrogen source, the maximum growth rate reached a value of 1.6 d -1 . C. raciborskii has fixed the atmospheric nitrogen even if other nitrogen source as NO 3 -N was available. The strategy of growth may depend on: 1 - nitrogen fixation, when other algae were nitrogen limited; 2 - fast PO 4 -P uptake even if very low concentration is available; and 3 - it has low light requirement, and high temperature.
Hydrobiologia, 2003
Morphological characteristics of Cylindrospermopsis raciborskii were investigated in batch cultur... more Morphological characteristics of Cylindrospermopsis raciborskii were investigated in batch culture under Pstarvation and in continuous cultures at two growth rates with different N forms. The species displayed an enormous morphological variability under controlled condition. In the P-starved batch culture very short and extreme morphology trichomes with conical or drop-shape heterocytes were formed. In continuous culture extremely long, twisted filaments were found near the maximum growth rate. Rarely, C. raciborskii formed intercalary heterocytes.
Freshwater Biology, Dec 1, 2005
1. This study introduces delayed fluorescence (DF) excitation spectroscopy as an on-line tool for... more 1. This study introduces delayed fluorescence (DF) excitation spectroscopy as an on-line tool for in situ monitoring of the composition and biomass of various colour classes of phytoplankton when they are photosynthetically active (cyanobacteria, chlorophytes, chromophytes and cryptophytes). The DF data are validated by comparison with those from conventional methods (weekly microscopic counts and the measurement of chlorophyll concentration). 2. The composition of phytoplankton as assessed by DF agreed reasonably well with the results from microscopic counts, particularly when differences in chlorophyll-specific DF integrals of the various colour classes were taken into account. 3. Integrals of DF spectra were converted into concentration of chlorophyll a using empirical factors derived from field data. The value of the conversion factor was nearly twice as high when the relative abundance of cyanobacteria was low (<15%) than when it was high. The converted DF-chl time series agreed well with chlorophyll measurements particularly when blooms were developing. As the DF method is inherently free of the interference caused by pigment degradation products, the discrepancy between the two data sets increased during the collapse of blooms and when sediment resuspension was intense. 4. Fourier spectrum analysis of the time series of DF-chl indicated that samples must be taken, at a minimum, every 2-3 days to capture the dynamics of phytoplankton. As a consequence, the dynamics of various algal blooms, including their timing, duration and net growth rate, could be estimated with greater confidence than by using conventional methods alone. 5. On-line DF spectroscopy is an advanced technique for monitoring daily the biomass and composition of the photosynthetically active phytoplankton in aquatic environments, including turbid shallow lakes. At present, the detection limit is around 1 mg DF-chl a m)3 in terms of total biomass but confidence in estimates of phytoplankton composition declines sharply below about 5 mg chl a m)3. 6. On-line DF spectroscopy represents a promising approach for monitoring phytoplankton. It will be useful in water management where it can act as an early-warning system of declines in water quality. In basic ecological research it can supplement
Turkish Journal of Fisheries and Aquatic Sciences, Jun 1, 2014
The Bitter Lake is the central and most important water body of the Suez Canal as it contains 85%... more The Bitter Lake is the central and most important water body of the Suez Canal as it contains 85% of the water of the canal system. This study reports the microplankton found occurring in the surface water of the Bitter Lake at monthly intervals from November 2008 until November 2009. A total of 130 taxa were identified, among which 67 taxa were of Bacillariophyceae, 15 Dinophyceae, 11 Chlorophyceae, 11 Cyanophyceae, 1 Euglenophyceae, 18 Tintinnidae, 4 Foraminiferidae, as well as 3 of Rotifera. Species diversity, numerical abundances and dynamics were analyzed for each taxon at three sites inside the Bitter Lake. At each of these sites Bacillariophyceae were predominant in the standing crop forming 67.2% of the total microplankton community with an average of 11,594 ind. L-1. The Dinophyceae occupied the second rank constituting about 16.5% of the total microplankton. Increase of microplankton abundance started in spring with maximum values being attained in late summer and early autumn (August), with an average of 37,498 ind. L-1 , while January was characterized by the lowest density (9,251 ind. L-1). Relatively higher diversity values were recorded at the northern part of the lake and a progressive decline in diversity was observed southward. Nutrient concentrations in the lake waters were very low, with silicate varying between 0.52-1.34 µM, phosphate between 0.14 and 0.55 µM and nitrate between 0.82-3.16 µmol L-1. Moreover, chlorophyll a fluctuated between 0.4 and 0.89 µg L-1. Data from microplankton analyses, nutrient (P) and chlorophyll a concentrations and transparency measurements were used to assess the ecosystem health of the Bitter Lake according to OECD, Canadian, and Quebec classification criteria, and it is concluded that the Bitter Lake be classified as an ultraoligotrophic lake.
Acta Biologica Hungarica, Mar 1, 2003
The freshwater cyanoprokaryote Cylindrospermopsis raciborskii has become increasingly prevalent i... more The freshwater cyanoprokaryote Cylindrospermopsis raciborskii has become increasingly prevalent in tropical and temperate water bodies worldwide. The morphological characteristics of this species were investigated under different growth rates in continuous cultures (at steady state) and in batch (phosphorus starved) cultures with different mineral nitrogen forms. The species displays an enormous morphological variability under controlled condition. The occurrence of extreme long twisted filaments was found near the maximum growth rate and under high ammonium concentration. Rarely the heterocytes of Cylindrospermopsis raciborskii arise intercalarly between two neighbouring cells (i.e. intercalary heterocytes were found). The morphological features are highly effected by environmental conditions and nutrient availability. Under P-starvation extreme morphology appeared. The specifications of C. africana and C. cuspis overlap with that of C. raciborskii accordingly this is not clear characteristic feature to distinguish species. A pure culture of a pro-or eukaryote alga growing in continuous cultures is a good method for giving a suitable overview on all morphological possibilities of a tested organism.
Annales De Limnologie-international Journal of Limnology, Sep 1, 1997
A strain of Cyclotella meneghiniana was isolated from the River Danube. The optimum irradiance an... more A strain of Cyclotella meneghiniana was isolated from the River Danube. The optimum irradiance and temperature for growth were determined in batch cultures. The optimum temperature for growth was 25 °C. The estimated saturated irradiance was near 125 uE m 2 s 1. The calculated I k for growth and photosynthesis were 30 ± 3 and 44 ± 6 uE nr 2 s 1 respectively. A continuous culture technique was used to test the growth and cell composition at the transition state between batch, nutrient sufficiency, and a low rate of nutrient supply. Algal response was characterized by high intracellular N and C with negative growth rate. At a low dilution rate (0.06 d 1), the continuous culture theory was not followed. This critical rate is characterized by low chlorophyll-a content per cell and may depend on the mode of nutrition.
Hydrobiologia, 2003
Ammonium and nitrate uptake and N 2-fixation of the heterocystous cyanoprokaryote Cylindrospermop... more Ammonium and nitrate uptake and N 2-fixation of the heterocystous cyanoprokaryote Cylindrospermopsis raciborskii was examined in continuous cultures under different nitrogen concentrations and dilution rates using the 15 N technique. It was found that at luxury phosphorus supply (5 mg PO 4-P l −1) the biomass was similar in all cultures irrespective of the amount and portioning (continuous or pulsed) of available nitrogen forms. The added ammonium and nitrate was fully taken up by C. raciborskii and the remaining nitrogen demand was met by N 2fixation. Different ammonium concentrations (300, 750, 1500 and 3000 µg 15 N l −1) added at the same dilution rate did not affect the growth of C. raciborskii. In the culture supplied with pulsed ammonium, N 2-fixation was detected prior to ammonium addition only. After the ammonium pulse, the N 2-fixation continued for a while then decreased and stopped. In addition, the inflowing ammonium was fully taken up by the organism. The rate of nitrogen fixation reached its original level after 8-24 hours, depending on the dilution rate. It can be suggested that the nitrogen fixation system stopped and was then activated again depending on the nitrogen content of the cells.
African Journal of Aquatic Science, Aug 27, 2010
... Menlo Park, California: Benjamin Cummings. Dewedar A, Bahgat M, Shabana EE. 2009. ... Journal... more ... Menlo Park, California: Benjamin Cummings. Dewedar A, Bahgat M, Shabana EE. 2009. ... Journal of Applied Bacteriology 140: 163188. El-Bana M, Khedr AH, van Hecke P, Bogaert J. 2002. Vegetation composition of a threatened hypersaline lake (Lake Bardawil), North Sinai. ...
Alfarama Journal of basic & applied sciences (Online), Jul 1, 2021
Navicula arenaria Donkin 1861 is a marine microalga belongs to class of bacillariophycea. Recentl... more Navicula arenaria Donkin 1861 is a marine microalga belongs to class of bacillariophycea. Recently, microalgae and their products are used as biological control of diseases caused by phytopathogenic fungi. This is considered environmentally ecofriendly method to overcome the plant damage caused by soil borne pathogenic fungi and thereby economic loss. Therefore, this study aimed to investigate in vitro the antifungal activity of N. arenaria isolate PS 31 extracellular and intracellular metabolites against two taxa of soil borne phytopathogenic fungi; Macrophomina phaseolina and Fusarium oxysporum. N. arenaria PS 31 hexane extract was the most effective extract on growth inhibition of both phytopathogenic fungi. There is no significant difference between miconazole and N. arenaria hexane extract of 5.6 mg/ml on growth inhibition of F. oxysporum. The inhibitory effect of hexane extract at 5.6, 4.2 and 2.8 mg/ml and ethyl acetate extract at 35% (v/v) was higher than controls. Ethyl acetate extract was effective on growth inhibition of M. phaseolina (29.67%). GC-MS analysis of N. arenaria hexane fraction revealed the presence of potent antifungal compounds such as Phenol, 2,2'-methylenebis[6-(1,1-dimethylethyl)-4methyl-, din -octyl phthalate, cholestane-3,5-diol, 5-acetate,(3.beta.,5.alpha.), Cholestan-3ol,(3.beta.,5.beta.)-and beta.-Sitosterol. These results suggest that N. arenaria hexane extract can be used in biological control of plant diseases caused by M. phaseolina and F. oxysporum.