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Articles 1381 - 1410 of 1681
Full-Text Articles in Biology
Quorum Sensing In Gram-Negative Bacteria, Gülgün Boşgelmez Tinaz
Quorum Sensing In Gram-Negative Bacteria, Gülgün Boşgelmez Tinaz
Turkish Journal of Biology
It has become increasingly and widely recognised that bacteria do not live as isolated entities but instead exist as communities that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions. A well-characterised example of such intercellular communication is quorum sensing. Quorum sensing depends on the production of diffusible signal molecules termed autoinducers or pheromones, which enable a bacterium to monitor its own cell population density. A variety of physiological processes in a range of bacterial species is regulated by quorum sensing. Examples include bioluminescence, antibiotic biosynthesis, swarming, biofilm differentiation, conjugation and the production of virulence …
Adventitious Shoot Organogenesis And Plant Regeneration From Cotyledons Of Diploid Diyarbakır Watermelon (Citrullus Lanatus Cv. "Sürme"), Vedat Pi̇ri̇nç, Ahmet Onay, Fi̇li̇z Adiyaman, Çi̇ğdem Işikalan, Engi̇n Ti̇lkat, Davut Başaran
Adventitious Shoot Organogenesis And Plant Regeneration From Cotyledons Of Diploid Diyarbakır Watermelon (Citrullus Lanatus Cv. "Sürme"), Vedat Pi̇ri̇nç, Ahmet Onay, Fi̇li̇z Adiyaman, Çi̇ğdem Işikalan, Engi̇n Ti̇lkat, Davut Başaran
Turkish Journal of Biology
Adventitious shoots were obtained from the diploid Diyarbakır watermelon cultivar "Sürme" by culturing cotyledons on shoot regeneration medium for 3 weeks. The effects of two cytokinins, benzyl amino purine (BA) and kinetine (Kin), on shoot organogenesis were examined. The number of shoots per explant were approximately more than 50% higher when 0.5 mg/l BA was used compared to the most effective kinetin concentration (1 mg/l). Plants were obtained by transferring 1 to 2 cm shoots to MS medium supplemented with 1-4 mg/l naphthalene acetic acid. Most of the regenerated plants (more than 50%) were successfully transplanted to the field. This …
Epipelic And Epilithic Algae Of Lower Parts Of Yanbolu River (Trabzon, Turkey), Bülent Şahi̇n
Epipelic And Epilithic Algae Of Lower Parts Of Yanbolu River (Trabzon, Turkey), Bülent Şahi̇n
Turkish Journal of Biology
The algae of Yanbolu River were investigated in samples collected from different habitats (epipelic, epilithic) at two stations between October 2000 and September 2001. The flora consisted of 78 taxa belonging to the Bacillariophyta (47 taxa), Cyanophyta (16 taxa), Chlorophyta (14 taxa) and Euglenophyta (1 taxon). The Bacillariophyta was the dominant form of algal flora. Amphora ovalis var. pediculus, Ceratoneis arcus, Cymbella affinis, C. minuta, Didymosphenia geminata, Melosira varians and Synedra ulna were the most frequent taxa in the algal flora. While the maximum density of the epipelic community was 29,555 cells/cm*2 at station I in June, it was 27,756 …
Investigation Of The Microfungal Flora Of The Bird Paradise National Park In Bandırma, Balıkesir (Turkey), Ayşe Di̇lek Azaz
Investigation Of The Microfungal Flora Of The Bird Paradise National Park In Bandırma, Balıkesir (Turkey), Ayşe Di̇lek Azaz
Turkish Journal of Biology
Fifteen soil samples taken from the Bird Paradise National Park in Bandırma were investigated using the soil dilution plate and soil washing methods. Thirty-three species and four different sterile microfungal taxa were identified. Twenty-eight of these species belonged to the Hyphomycetes and 5 to the Mucorales. The genus with the highest species diversity found in the study area was Penicillium, represented by 16 species. Some chemical properties of the soil samples were also established. Quantitative analysis based on the soil dilution plate method revealed a statistically significant difference between soil samples subjected to the rising water level of the lake …
Characterization Of Salivaricin B, A Protein Expressed By Lactobacillus Salivarius M7, Osman Çataloluk, Candan G. Gürakan
Characterization Of Salivaricin B, A Protein Expressed By Lactobacillus Salivarius M7, Osman Çataloluk, Candan G. Gürakan
Turkish Journal of Biology
Salivaricin B (SalB) is a protein encoded by Lactobacillus salivarius M7. This protein is insensitive to proteolytic enzymes, such as pepsin, trypsin, and chymotrypsin, but is partially sensitive to proteinase K. SalB is also stable and maintains its activity over a range of pHs, from 3 to 9. SalB was found to be effective against many closely related lactic acid bacteria such as, L. fermentum, L. plantarum, L. acidophilus and distantly related gram-positive bacteria, including Listeria monocytogenes, Streptococcus faecalis, Staphylococcus aureus and Staph. epidermidis. The mode of action of SalB was obviously bactericidal, and death occurs without bacterial lysis. The …
Modification By Compositional Antimutagens Of The Key Stages Of A Mutation Process, Urkhan Alekperov, Ali Aliev, Afet Rustamova, Saida Jafarova
Modification By Compositional Antimutagens Of The Key Stages Of A Mutation Process, Urkhan Alekperov, Ali Aliev, Afet Rustamova, Saida Jafarova
Turkish Journal of Biology
In experiments with Escherichia coli B/r WP2(trpE-), mice marrow cells and human lymphocytes the antimutagenic activity of an extract from Zizyphus mill was performed. The extract was tested separately and in mixture with Triticum aestivum. In experiments with different treatment schemes it has been established that the extract from wheat sprouts added to an antimutagenic preparation from Zizyphus mill intensifies the genoprotective properties of the Zizyphus mill extract.
The Effects Of Dietary Fatty Acids On The Fatty Acid Composition In The Phospholipid Fraction Of Gambusia Affinis, Eli̇f İpek Cengi̇z, Erhan Ünlü, Mehmet Başhan
The Effects Of Dietary Fatty Acids On The Fatty Acid Composition In The Phospholipid Fraction Of Gambusia Affinis, Eli̇f İpek Cengi̇z, Erhan Ünlü, Mehmet Başhan
Turkish Journal of Biology
The present study represents an investigation into the effect of dietary fatty acids on the fatty acid composition of the phospholipid fraction of Gambusia affinis, a small freshwater fish living in a source located on the campus of Dicle University. The fatty acid composition of the phospholipid fraction was analysed by gas chromatography for fish collected from the freshwater source, which were naturally fed, and also fish fed an artificial diet with a w6/w3 ratio of 5.5:1 for 30 days. The level of w3 in the fish fed artificially for 30 days was higher than in those collected from the …
Evaluation Of The Reproductive Potential And Competition Between Two Entomopathogenic Nematodes, Steinernema Feltiae Filipjev, 1934 (Rhabditida: Steinernematidae) And Heterorhabditis Bacteriophora, Poinar 1976 (Rhabditida: Heterorhabditidae), Işik Oğuzoğlu Ünlü, Nurdan Özer
Evaluation Of The Reproductive Potential And Competition Between Two Entomopathogenic Nematodes, Steinernema Feltiae Filipjev, 1934 (Rhabditida: Steinernematidae) And Heterorhabditis Bacteriophora, Poinar 1976 (Rhabditida: Heterorhabditidae), Işik Oğuzoğlu Ünlü, Nurdan Özer
Turkish Journal of Biology
The emergence in Galleria mellonella (L.) larva, which was infected by Steinernema feltiae and Heterorhabditis bacteriophora, began on the ninth day after exposure to the former nematode and the sixth day of exposure to the latter nematode (25 ± 0.5 ºC). The average number of nematodes developing in each host was as 13,829, and the range was from 4365 to 27,510 for S. feltiae infection. The average number of nematodes per host was 141,562, and the range was 50,905 - 271,593 for H. bacteriophora infection. When the 2 different species were inoculated simultaneously into the same host, H. bacteriophora caused …
The Effect Of Tannery Effluent On The Colonization Rate Of Plankters: A Microcosm Study, Yalavarthi Naga Koteswari, Ravichandran Ramanibai
The Effect Of Tannery Effluent On The Colonization Rate Of Plankters: A Microcosm Study, Yalavarthi Naga Koteswari, Ravichandran Ramanibai
Turkish Journal of Biology
The present study describes a multispecies toxicity test that uses community level responses of plankton samples from a natural lake using polyurythane foam (PF) as artificial substrate. These substrates were suspended and left for a period of 14 days. Colonized substrates were then placed in a series of microcosms dosed with a gradient of tannery effluent from 1 to 15% concentration. The species composition and abundance of the planktonic communities in PF substrate with the exposure of 4 different concentration of tannery effluent (1%, 3%, 5% and 15%) were assessed on days 1, 3, 7, 14, 21 and 28. Species …
Classification Of Strains Of Bacillus Sphaericus By Different Statistical Methods, Nazi̇me Mercan, Atalay Çağlar, Belma Aslim, Yavuz Beyatli
Classification Of Strains Of Bacillus Sphaericus By Different Statistical Methods, Nazi̇me Mercan, Atalay Çağlar, Belma Aslim, Yavuz Beyatli
Turkish Journal of Biology
In this study, the sensitivies of 21 strains of Bacillus sphaericus to 20 different antibiotics were determined with the antibiotic disc susceptibility test. By measuring the diameters of the inhibition zones in terms of millimetres, the obtained values were analysed using the SPSS for Windows package and classifications were made. With these analyses, 21 strains were clustered into 5 groups. In our study, strains IAB 59 and 2297 were placed into a separate class. In addition, those antibiotics which caused a differentation in strains and a discrimination of strains according to the level of antibiotic effect were determined.
Host Finding Behavior Of Two Different Turkish Isolates Of Entomopathogenic Nematode Species, Heterorhabditis Bacteriophora, Poinar 1976 (Rhabditida: Heterorhabditidae), İ. Alper Susurluk, Işik O. Ünlü, İlker Kepenekci̇
Host Finding Behavior Of Two Different Turkish Isolates Of Entomopathogenic Nematode Species, Heterorhabditis Bacteriophora, Poinar 1976 (Rhabditida: Heterorhabditidae), İ. Alper Susurluk, Işik O. Ünlü, İlker Kepenekci̇
Turkish Journal of Biology
The movement of 2 different isolates of an insect parasitic nematode species (Heterorhabditis bacteriophora Tur-H2 and H. bacteriophora Tur-H1) in vertical columns was tested under laboratory conditions. We have found significant differences in the movements of H. bacteriophora Tur-H2 and H. bacteriophora Tur-H1 towards the Galleria mellonella larvae as a host. The maximum nematode infection rate inside the host was observed on the third day of the trial period for both species. We have recorded the number and the given percentage of infective juveniles (IJs) of H. bacteriophora Tur-H2 that moved towards the G. mellonella larvae within 24, 48, 72, …
Melatonin Implants Have No Effect On The Testis Volume And Body Weight In Mongolian Gerbils, Alper Karakaş, Bülent Gündüz
Melatonin Implants Have No Effect On The Testis Volume And Body Weight In Mongolian Gerbils, Alper Karakaş, Bülent Gündüz
Turkish Journal of Biology
Photoperiod is an important environmental cue in the regulation of reproductive activity in Mongolian gerbils. Photoperiodic information is ultimately transduced into a hormonal signal by the pineal gland. We examined the effect of constant-release melatonin capsules on the testicular size and body weights of male Mongolian gerbils exposed to a long (14L: 10D) photoperiod. Three groups were formed: control (n = 10), intact + melatonin implant (n = 10) and pinealectomy + melatonin implant (n = 10). The testes and body weights of the gerbils were recorded every week for 8 weeks. Body weights (76 ± 2.0 g intact + …
Failure Of Regeneration Of Sensory Nerve Fibers Following Neonatal Denervation And Crush Lesion In Rats, Jumah Shakhanbeh, Khaled Khleifat
Failure Of Regeneration Of Sensory Nerve Fibers Following Neonatal Denervation And Crush Lesion In Rats, Jumah Shakhanbeh, Khaled Khleifat
Turkish Journal of Biology
The effects of chronic neonatal denervation and a crush lesion on the regenerative capacity of sensory nerve fibers were studied in rats. After 50 weeks of postnatal denervation, the amplitudes of compound action potentials (CAPs) of A\alpha\beta-, A\delta- and C-fibers were reduced to 14.3%, 18.2% and 37.4%, respectively (P < 0.005). Similarly, after a crush lesion, the amplitudes of CAPs were reduced to 34.3%, 38.8% and 51.6%, respectively (P < 0.005). The conduction velocities, thresholds and maximum strength of stimulation of nerve fibers were normal. Neurogenic plasma extravasation into the skin due to antidromic nerve stimulation was reduced to 27.5% and 30.3% after postnatal denervation and the crush lesion, respectively (P < 0.005). These results indicate that neonatal sensory nerve injury induces permanent neurodegeneration of peripheral sensory nerve fibers as demonstrated by the inhibition of afferent conduction property and efferent neurogenic plasma extravasation response.
The Analysis Of Partial Dominance Of Intragenic Mutations At The Adh Locus In Drosophila Melanogaster At Two Different Alcohol Concentrations, Vatan Taşkin
Turkish Journal of Biology
The dominance of a de novo mutation determines its effect on the viability of the first and succeeding generations; therefore, it is a major factor in estimating the risk from mutations to human health. It is well established that large deletions lead to significant dominance, but until the recent development of molecular methods for amplification and sequencing of mutations it was not possible to determine the dominance of specific intragenic changes in DNA. The purpose of this study was to determine the dominance for a series of Adh-null mutations, each with a minimum mutation of a transition at one base …
Analysis Of The Effects Of Transcription Factors Gcr2p And Sgc1p On The Control Of The Suc2 Gene Expression In Saccharomyces Cerevisiae, Sezai̇ Türkel, Tülay Turgut, İpek Savaşçioğlu
Analysis Of The Effects Of Transcription Factors Gcr2p And Sgc1p On The Control Of The Suc2 Gene Expression In Saccharomyces Cerevisiae, Sezai̇ Türkel, Tülay Turgut, İpek Savaşçioğlu
Turkish Journal of Biology
The transcription of the SUC2 gene is regulated by glucose repression and the derepression mechanism in the yeast Saccharomyces cerevisiae. The Mig1p-Tup1p-Ssn6p repressor complex, hexokinase PII and nucleosomes are required for the repression of the SUC2 gene. The Snf/Swi and SAGA complexes act on Mig1p and nucleosomes in low glucose media. SUC2 transcription thus becomes activated. In this study, it is shown that the transcription factors Gcr2p and Sgc1p are also required for the high level transcription of the SUC2 gene. SUC2 transcription and the invertase synthesis decreased at significant levels in gcr2 and sgc1 mutant yeast cells. In addition, …
Anti-Genotoxic Effect Of Ascorbic Acid On Mutagenic Dose Of Three Alkylating Agents, Bülent Kaya
Anti-Genotoxic Effect Of Ascorbic Acid On Mutagenic Dose Of Three Alkylating Agents, Bülent Kaya
Turkish Journal of Biology
The antimutagenic effect of ascorbic acid (vitamin C) was investigated by using the Drosophila wing spot test. In this assay, 3-day-old transheterozygous larvae for the multiple wing hair (mwh, 3-0.3) and flare (flr, 3-38.8) genes were treated with 3 direct acting mutagens: ethyl methanesulfonate (EMS), methyl methanesulfonate (MMS) and N-nitroso N-ethylurea (ENU). The results obtained from 3 reference mutagens were clearly genotoxic in the Drosophila wing somatic mutation and recombination test. The calculated concentration of ascorbic acid as recommended dietary allowance (RDA) did not induce the frequency of the mutant clones recorded. When co-treatment experiments with ascorbic acid were carried …
Isolation Of Trichoderma Spp. And Determination Of Their Antifungal, Biochemical And Physiological Features, Çi̇ğdem Küçük, Meri̇h Kivanç
Isolation Of Trichoderma Spp. And Determination Of Their Antifungal, Biochemical And Physiological Features, Çi̇ğdem Küçük, Meri̇h Kivanç
Turkish Journal of Biology
It is well known that Trichoderma spp. can be used as a biological control agent. In this study, Trichoderma isolates were obtained from 31 different Eskisehir soil samples. The biocontrol and antifungal effects of these isolates against various plant pathogen fungi were determined. We found that all filtrates of Trichoderma harzianum T9, T10, T15 and T19 were effective against plant pathogens Fusarium culmarum, F. oxysporum, F. moniliforme, Rhizoctonia solani, Sclerotium rolfsii, Gaeumannomyces graminis var. tritici and Drechslera sorokiniana. Among these isolates, T. harzianum T19 showed a wide range of inhibitory effects on plant pathogens. F. oxysporum was found to be …
Antimicrobial Activity Of Viscum Album L. Subsp. Abietis (Wiesb), Ömer Ertürk, Hati̇ce Kati, Nuretti̇n Yayli, Zi̇hni̇ Demi̇rbağ
Antimicrobial Activity Of Viscum Album L. Subsp. Abietis (Wiesb), Ömer Ertürk, Hati̇ce Kati, Nuretti̇n Yayli, Zi̇hni̇ Demi̇rbağ
Turkish Journal of Biology
Viscum album L. subsp. abietis (Wiesb.) (Loranthaceae) is extensively used for treatment in traditional medicine. This plant was collected in the region of Artvin, northern Turkey. Different concentrations of n-hexane extract were tested using the agar diffusion technique against 6 bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae and Proteus vulgaris), and 1 fungus (Candida albicans). We determined that fractions 6 and 7 of n-hexane extract of V. album subsp. abietis showed antimicrobial activity against the micro-organisms tested.
The Development Of A Modified Method For Isolating Plasmids From Exopolysaccharide Producing Lactobacillus Species Using Conventional Plasmid Isolation Methods, Osman Çataloluk
Turkish Journal of Biology
Lactic acid bacteria (LAB) are a key element in the dairy industry. The gene products encoded by the plasmids of LAB carry out fermentation. To date, many successful plasmid isolation studies have been conducted with Escherichia coli, Staphilococcus, Streptococcus, Salmonella, Listeria and many strains of LAB. However, since LAB comprise a conglomerate of seven different genera, each with its own physiological and morphological characteristics, and produce a large amount of exopolysaccharide coat, it is extremely difficult to obtain plasmids by conventional methods. A field isolate of lactobacillus known as Lactobacillus salivarius M7 was utilized to obtain plasmids by all known …
Antimicrobial Activities Of Various Medicinal And Commercial Plant Extracts, D. Ayfer Ateş, Özlem Turgay
Antimicrobial Activities Of Various Medicinal And Commercial Plant Extracts, D. Ayfer Ateş, Özlem Turgay
Turkish Journal of Biology
The antibacterial activities of the alcohol, ethyl acetate, acetone and chloroform extracts of 5 plant species were studied. The extracts of Pimpinella anisum (L.) (anise, aniseed) (seed), Coriandrum sativum (L.) (coriander, cilantro) (seed), Glycyrrhiza glabra (L.) (liquorice) (root), Cinnamomum cassia Blume (cassia bark, Chinese cinnamon) (bark), and Juniperus oxycedrus (L.) (juniper) (seed) were tested in vitro against 13 bacterial species and strains by the agar diffusion method. Bacillus brevis FMC 3, Bacillus cereus EU, Bacillus megaterium DSM 32, Bacillus subtilis IMG 22, Bacillus subtilis var. niger ATCC 10, Enterococcus faecalis, Klebsiella pneumoniae FMC 5, Listeria monocytogenes SCOTT A, Micrococcus luteus …
Entomopathogenic Nematodes (Steinernematidae And Heterorhabditidae) For Biological Control Of Soil Pests, Selçuk Hazir, Harry K. Kaya, S. Patricia Stock, Nevi̇n Keski̇n
Entomopathogenic Nematodes (Steinernematidae And Heterorhabditidae) For Biological Control Of Soil Pests, Selçuk Hazir, Harry K. Kaya, S. Patricia Stock, Nevi̇n Keski̇n
Turkish Journal of Biology
Several species of entomopathogenic nematodes in the families Steinernematidae (Steinernema) and Heterorhabditidae (Heterorhabditis) are being produced commercially and used as biological control agents against many soil insect pests and insects in cryptic habitats in many parts of the world. These nematodes, which are mutualistically associated with bacteria (Steinernema with Xenorhabdus bacteria and Heterorhabditis with Photorhabdus bacteria), offer a number of advantages because they have a broad host range, kill their hosts within 48 h, can be easily produced in vivo and in vitro, can be applied with standard spray equipment, are safe to humans and other non-target organisms, have no …
In Vivo And In Vitro Micrografting Of Pistachio, Pistacia Vera L. Cv. "Siirt", Ahmet Onay, Vedat Pi̇ri̇nç, Fi̇li̇z Adiyaman, Çi̇ğdem Işikalan, Engi̇n Ti̇lkat, Davut Başaran
In Vivo And In Vitro Micrografting Of Pistachio, Pistacia Vera L. Cv. "Siirt", Ahmet Onay, Vedat Pi̇ri̇nç, Fi̇li̇z Adiyaman, Çi̇ğdem Işikalan, Engi̇n Ti̇lkat, Davut Başaran
Turkish Journal of Biology
In this study, the success of in vivo and in vitro micrografts of pistachio (Pistacia vera L. cv. "Siirt") materials are presented. The only variable tested was age (1, 5, 10, and 30-year-old trees). Ten- to 12-day-old axenic seedlings germinated in vitro or seedlings (3 to 5 months-old) grown in pots in vivo were used as rootstocks. Shoot tips collected from the four age classes of mature trees of pistachio were the source of scions. Firm contact between the scion and rootstock was assured through the use of parafilm tape at the graft junction for in vivo micrografts. The in …
Electrophoretic Aspects Of Blood Serum Proteins Of The Genus Apodemus In The Black Sea Region, Reyhan Çolak
Electrophoretic Aspects Of Blood Serum Proteins Of The Genus Apodemus In The Black Sea Region, Reyhan Çolak
Turkish Journal of Biology
Globulin and albumin proteins of Apodemus populations in the Black Sea region were examined using SDS-PAGE (sodium dodecyl sulphate - polyacrylamide gel electrophoresis). There were 7-11 bands in the globulin region and 1-3 bands in the prealbumin zone. It was determined that there were variations in both the globulin region and the prealbumin zone in populations of this genus. A band was observed in the postalbumin zone with different electrophoretic mobilities including slow and fast. This different mobility in the postalbumin zone separated Apodemus specimens into two different populations in sympatry. These findings showed that at least two populations of …
Partial Purification Of Intestinal Triglyceride Lipase From Cyprinion Macrostomus Heckel, 1843 And Effect Of Ph On Enzyme Activity, Naci̇ Değerli̇, M. Ali̇ Akpinar
Partial Purification Of Intestinal Triglyceride Lipase From Cyprinion Macrostomus Heckel, 1843 And Effect Of Ph On Enzyme Activity, Naci̇ Değerli̇, M. Ali̇ Akpinar
Turkish Journal of Biology
Intestinal triglyceride lipase (TG) of Cyprinion macrostomus after precipitation with 30% polyethylene glycol (PEG), was partially purified by hydrophobic interaction chromatography on phenyl sepharose CL-4B, and the effect of pH on this enzyme activity was determined titrimetrically. Intestinal tissue homogenates were precipitated using 30% PEG-8000, and then applied onto a phenyl sepharose CL-4B column for hy-drophobic interaction chromatography. The lipase that bound to this hydrophobic resin and was partially purified by this single step application was then eluted from this resin with taurocholic acid and Triton X-100 elution. This purified enzyme effectively hydrolysed natural olive oil substrate under the experimental …
Hydroxyurea Induces P53 Accumulation And Apoptosis In Human Cervical Carcinoma Cells, Hakan Akça, Osman Ni̇dai̇ Özeş
Hydroxyurea Induces P53 Accumulation And Apoptosis In Human Cervical Carcinoma Cells, Hakan Akça, Osman Ni̇dai̇ Özeş
Turkish Journal of Biology
Cervical carcinoma is one type of cancer with a high mortality rate in women. In this research, we investigated the cytotoxic, antiproliferative and apoptosis-inducing effects of hydroxyurea on a human cervical carcinoma cell line, HeLa. We found that hydroxyurea has cytotoxic and antiproliferative effects on HeLa cells in a dose-dependent manner. We also found that hydroxyurea can increase cellular levels of p53 and p21, and induce DNA fragmentation in a dose-dependent manner. We concluded that the observed antiproliferative, cytotoxic and apoptosis inducing activities of hydroxyurea might be mediated by the induction of p53 and its transcriptional target, p21.
Analysis Of The Effects Of Hyperosmotic Stress On The Derepression Of Invertase Activities And The Growth Of Different Baker's Yeast Strains, Sezai̇ Türkel, Tülay Turgut
Analysis Of The Effects Of Hyperosmotic Stress On The Derepression Of Invertase Activities And The Growth Of Different Baker's Yeast Strains, Sezai̇ Türkel, Tülay Turgut
Turkish Journal of Biology
The growth of baker's yeast Saccharomyces cerevisiae in medium containing sucrose requires a high level of extracellular invertase enzyme activity. However, the expression of invertase is under the strict control of glucose repression in S. cerevisiae. In addition, invertase enzyme activity is also affected by physiological stress conditions that baker's yeast is exposed to during the various stages of industrial level production and downstream processing. We analyzed the effect of hyperosmotic stress on the derepression of invertase activities of a haploid laboratory yeast strain and three different industrial baker's yeast strains. Our results indicated that hyperosmotic stress interferes with the …
Effect Of Experimental Diabetes Mellitus On Plasma Lactate Dehydrogenase And Glutamic Oxaloacetic Transaminase Levels In Rabbits, İsmai̇l Çeli̇k, Eşref Yeği̇n, Fehmi̇ Odabaşoğlu
Effect Of Experimental Diabetes Mellitus On Plasma Lactate Dehydrogenase And Glutamic Oxaloacetic Transaminase Levels In Rabbits, İsmai̇l Çeli̇k, Eşref Yeği̇n, Fehmi̇ Odabaşoğlu
Turkish Journal of Biology
Hyperglycemia was induced in 20 male, white, New Zealand rabbits (2-3 kg) (Oryctolagus cuniculus huxley) by alloxan (100 mg/kg body weight, I.V.) and maintained for 16 weeks without insulin treatment. Blood samples were taken from both diabetic and non-diabetic rabbits at the same time for measurement of plasma enzymes. Levels of glutamic oxalacetic transaminase (GOT) and lactate dehydrogenase (LDH) were determined after treatment. The levels of LDH and GOT were 155.6 ± 41.9 U/L and 47.0 ± 20.4 U/L in the control group respectively. These parameters were 286.9 ± 142.9 U/L and 93.9 ± 62.5 U/L in the diabetic group …
Protoplast Fusion In Sugar Beet (Beta Vulgaris L.), Songül Gürel, Ekrem Gürel, Zeki̇ Kaya
Protoplast Fusion In Sugar Beet (Beta Vulgaris L.), Songül Gürel, Ekrem Gürel, Zeki̇ Kaya
Turkish Journal of Biology
In this study, attempts were made to fuse the suspension-derived protoplasts of a sugar beet breeding line (ÇBM315) with the mesophyll-derived protoplasts of three breeding lines (M114, ELK345 and M1017), which were obtained from our previous experiments. Combinations of three different PEG concentrations (20%, 25% or 30%) and three different treatment durations (15, 20 or 25 min) were tested. The fusion efficiency was determined by measuring the viability, heterokaryon frequency and plating efficiency (PE) of the fused protoplasts after four weeks of culture. In general, 25% PEG combined with 20 min treatment duration produced the highest fusion frequency, but the …
Accumulation Of Poly-\Beta-Hydroxybutyrate In Streptomyces Species During Growth With Different Nitrogen Sources, Aysel Uğur, Nuretti̇n Şahi̇n, Yavuz Beyatli
Accumulation Of Poly-\Beta-Hydroxybutyrate In Streptomyces Species During Growth With Different Nitrogen Sources, Aysel Uğur, Nuretti̇n Şahi̇n, Yavuz Beyatli
Turkish Journal of Biology
The accumulation of poly-\beta-hydroxybutyric acid (PHB) in 27 Streptomyces isolates with different taxonomical properties was investigated. The amount of synthesized PHB was determined as crotonic acid by spectrophotometry. Eighty percent of the tested isolates accumulated PHB between 0.3 and 7.6% of dry mycelial weight. PHB was produced by a selectant of Streptomyces isolates in media containing different nitrogen sources (KNO_3, glycine, peptone, proteose peptone, L-asparagine, tryptone and malt extract), each combined with 2 g/l glucose as the carbon source. The most effective PHB production was observed on glycine/glucose medium with a 7.6% dry mycelial weight. Nitrogen limiting conditions were inhibitory …
Embryo Culture In Barley (Hordeum Vulgare L.), Betül Bürün, Esi̇n Çoban Poyrazoğlu
Embryo Culture In Barley (Hordeum Vulgare L.), Betül Bürün, Esi̇n Çoban Poyrazoğlu
Turkish Journal of Biology
The effects of medium and sterilization on the mature embryo culture of barley (Hordeum vulgare L.) were studied. Among the different media used, the highest plantlet development from embryos was obtained in Randolph and Cox medium (92.1%), followed by Murashige and Skoog (MS) (91.3%), half-strength MS (1/2 MS) (87.7%) and B5 (85.7%). Among the sterilization methods studied, sodium hypochlorite sterilization followed by treatment of antibiotic solution and sterilization HgCl_2 application was found to be more effective than the other methods. However, no statistically significant negative effect of HgCl_2 on the plantlet development from embryos was observed.