Browsing by Subject "Animals"

Now showing 1 - 20 of 68

Open Access
4,5-dianilinophtalimide protects neuroendocrine cells against serum deprivation-induced stress and apoptosis
(2013) Ergin V.; Erdogan, M.; Karasu Ç.; Menevşe, A.
OBJECTIVE: The aim of this study was to reveal the effects of 4,5-dianilinophthalimide (DAPH), which inhibits amyloid β fibrillization, against serum deprivation (SD)-induced apoptosis and the possible mechanisms in differentiated PC12 neuron cells. METHODS: Firstly, we evaluated whether DAPH protects cell viability exposed to SD by MTT assay. Next, we examined the changes of phospho-p38 MAPK (Thr180/Tyr182), phospho-HSP27 (Ser82), phospho-c-JUN (Ser73) and cleaved-CASP3 (Asp175) profiles by immunoblotting, in PC12 cells exposed to SD. Intracellular reactive oxygen species (ROS) level was also measured. RESULTS: SD induced apoptosis accompanied by up-regulation of phospho-p38 MAPK (Thr180/Tyr182), phospho-HSP27 (Ser82), phospho-c-JUN (Ser73), cleaved-CASP3 (Asp175) and intracellular ROS content. Co-treatment with nontoxic doses of DAPH prevented apoptosis by the attenuation of activated proteins and reduction of ROS level. These results suggest that serum deprivation-induced apoptosis inhibited by DAPH administration. CONCLUSION: We have provided for the first evidence that DAPH has a neuroprotective effect on SD-caused stress, probably via contributing the reestablishment of redox homeostasis. © 2013 Neuroendocrinology Letters.
Open Access
“And to every beast of the earth and to every bird of the heaven and to everything that creeps on the earth”: animals in Byzantium
(2022-05) Mulla, Ayşenur
This thesis examines the relationship between the Byzantines and animals (in particular small ones like worms and bees) in terms of practical, socio-economic, and religious terms mainly using the written sources (hagiographies, ancient scientific sources, miracle stories, or legal documents), archaeological, zooarchaeological, and architectural remains from different areas of the Byzantine Empire. The main idea of the thesis stems from socio-cultural and religious studies of the Byzantine society, which (with the exception of a few scholars like Sophia Germanidou, Henrietta Kroll, Nancy Sevcenko, and Tristan Schmidt, who have studied the Byzantine animals and their mentality about the world of bestiary), has mostly focused on the economics of animals and their rearing. In fact, and contrary to the mainstream historiography, this study tries to bridge a gap between the role of the animals, especially the smallest ones like worms, bees, insects, and silkworms, as they have tended to be forgotten when examining the socio-cultural and economic dynamics of Byzantine society at large. Bearing in mind the limits and the problems of sources, both primary and secondary, the main goal of this thesis is to scrutinize the Byzantine narrative about these animals, to recreate the Byzantine perception and utilization of the other living beings as well as to understand the multi-faceted benefits of the presence of animals in the daily life of the Byzantines.
Open Access
Angiogenic peptide nanofibers repair cardiac tissue defect after myocardial infarction
(Acta Materialia Inc, 2017) Rufaihah, A. J.; Yasa, I. C.; Ramanujam, V. S.; Arularasu, S. C.; Kofidis, T.; Güler, Mustafa O.; Tekinay, A. B.
Myocardial infarction remains one of the top leading causes of death in the world and the damage sustained in the heart eventually develops into heart failure. Limited conventional treatment options due to the inability of the myocardium to regenerate after injury and shortage of organ donors require the development of alternative therapies to repair the damaged myocardium. Current efforts in repairing damage after myocardial infarction concentrates on using biologically derived molecules such as growth factors or stem cells, which carry risks of serious side effects including the formation of teratomas. Here, we demonstrate that synthetic glycosaminoglycan (GAG) mimetic peptide nanofiber scaffolds induce neovascularization in cardiovascular tissue after myocardial infarction, without the addition of any biologically derived factors or stem cells. When the GAG mimetic nanofiber gels were injected in the infarct site of rodent myocardial infarct model, increased VEGF-A expression and recruitment of vascular cells was observed. This was accompanied with significant degree of neovascularization and better cardiac performance when compared to the control saline group. The results demonstrate the potential of future clinical applications of these bioactive peptide nanofibers as a promising strategy for cardiovascular repair. Statement of Significance We present a synthetic bioactive peptide nanofiber system can enhance cardiac function and enhance cardiovascular regeneration after myocardial infarction (MI) without the addition of growth factors, stem cells or other biologically derived molecules. Current state of the art in cardiac repair after MI utilize at least one of the above mentioned biologically derived molecules, thus our approach is ground-breaking for cardiovascular therapy after MI. In this work, we showed that synthetic glycosaminoglycan (GAG) mimetic peptide nanofiber scaffolds induce neovascularization and cardiomyocyte differentiation for the regeneration of cardiovascular tissue after myocardial infarction in a rat infarct model. When the peptide nanofiber gels were injected in infarct site at rodent myocardial infarct model, recruitment of vascular cells was observed, neovascularization was significantly induced and cardiac performance was improved. These results demonstrate the potential of future clinical applications of these bioactive peptide nanofibers as a promising strategy for cardiovascular repair.
Open Access
Animals and diplomacy: on the prospect for interspecies diplomacy
(SAGE Publications, 2023-08-10) Fougner, Tore
If diplomacy is considered an alternative to war, can the ongoing human ‘war against animals’ be replaced with diplomacy between humans and other animals? While many scholars and practitioners of diplomacy can be expected to dismiss such an idea out of hand, this essay encourages us to think more seriously and thoroughly about what it might imply to engage diplomatically with nonhuman animals. Doing so requires a somewhat unconventional conception of diplomacy, and some scholars have already done much to rethink diplomacy in suitable ways (despite the persistent anthropocentrism). Combining such work with political science scholarship on human-animal relations, indigenous peoples’ relations with animals, various notions of animal ambassadorship and the study of animal behaviour in natural settings, the essay argues that interspecies diplomacy is possible and urges scholars to further explore this and how the possibility in question can be translated into reality.
Open Access
Antiangiogenic response after 70% hepatectomy and its relationship with hepatic regeneration and angiogenesis in rats
(2010) Dogrul, A.B.; Colakoglu, T.; Kosemehmetoglu, K.; Birben, E.; Yaman, E.; Gedikoglu G.; Abbasoglu O.
Background: The aim of this study was to evaluate the antiangiogenic response and its relation to regeneration and angiogenesis after 70% hepatectomy in a rat model. Methods: Sixty-four Wistar albino rats were included in the study. Animals were allocated into 8 groups (n = 8). After a 70% hepatectomy, liver regeneration, angiogenesis, and antiangiogenic response were evaluated in the remnant liver on days 0, 1, 2, 3, 5, 7, 10, and 14. Regeneration and angiogenesis were determined with immunoreactivity to proliferating cell nuclear antigen and vascular endothelial growth factor. Antiangiogenic response was evaluated by detecting collagen 18 m RNA with reverse transcriptase polymerase chain reaction. Results: We showed that liver regeneration peaked at day 1, whereas angiogenesis in the periportal and perisinusoidal areas reached their peak values on days 3 and 7, respectively. Both regeneration and angiogenic activity around perisinusoidal hepatocytes returned to basal activity on the day 10. Antiangiogenic response first appeared on day 5, reached a peak on day 10, and returned to basal values on day 14. Conclusion: Collagen18 mRNA expression is present in the normal liver during the regenerative process. We suggest that the stimulus that causes the cessation of regeneration process may come from hepatocytes, and collagen 18 produced by hepatocytes may modulate this event by inhibiting the angiogenesis. © 2010 Mosby, Inc. All rights reserved.
Open Access
Application of a customized pathway-focused microarray for gene expression profiling of cellular homeostasis upon exposure to nicotine in PC12 cells
(2004) Konu Ö.; Xu X.; Ma J.Z.; Kane J.; Wang J.; Shi, S.J.; Li, M.D.
Maintenance of cellular homeostasis is integral to appropriate regulation of cellular signaling and cell growth and division. In this study, we report the development and quality assessment of a pathway-focused microarray comprising genes involved in cellular homeostasis. Since nicotine is known to have highly modulatory effects on the intracellular calcium homeostasis, we therefore tested the applicability of the homeostatic pathway-focused microarray on the gene expression in PC-12 cells treated with 1 mM nicotine for 48 h relative to the untreated control cells. We first provided a detailed description of the focused array with respect to its gene and pathway content and then assessed the array quality using a robust regression procedure that allows for the exclusion of unreliable measurements while decreasing the number of false positives. As a result, the mean correlation coefficient between duplicate measurements of the arrays used in this study (control vs. nicotine treatment, three samples each) has increased from 0.974±0.017 to 0.995±0.002. Furthermore, we found that nicotine affected various structural and signaling components of the AKT/PKB signaling pathway and protein synthesis and degradation processes in PC-12 cells. Since modulation of intracellular calcium concentrations ([Ca2+]i) and phosphatidylinositol signaling are important in various biological processes such as neurotransmitter release and tissue pathogenesis including tumor formation, we expect that the homeostatic pathway-focused microarray potentially can be used for the identification of unique gene expression profiles in comparative studies of drugs of abuse and diverse environmental stimuli, such as starvation and oxidative stress. © 2003 Elsevier B.V. All rights reserved.
Open Access
An approximate stance map of the spring mass hopper with gravity correction for nonsymmetric locomotions
(IEEE, 2009) Arslan, Ömür; Saranlı, Uluç; Morgül, Ömer
The Spring-Loaded Inverted Pendulum (SLIP) model has long been established as an effective and accurate descriptive model for running animals of widely differing sizes and morphologies, while also serving as a basis for several hopping robot designs. Further research on this model led to the discovery of several analytic approximations to its normally nonintegrable dynamics. However, these approximations mostly focus on steady-state running with symmetric trajectories due to their linearization of gravitational effects, an assumption that is quickly violated for locomotion on more complex terrain wherein transient, non-symmetric trajectories dominate. In this paper, we introduce a novel gravity correction scheme that extends on one of the more recent analytic approximations to the SLIP dynamics and achieves good accuracy even for highly non-symmetric trajectories. Our approach is based on incorporating the total effect of gravity on the angular momentum throughout a single stance phase and allows us to preserve the analytic simplicity of the approximation to support our longer term research on reactive footstep planning for dynamic legged locomotion. We compare the performance of our method in simulation to two other existing analytic approximations and show that it outperforms them for most physically realistic non-symmetric SLIP trajectories while maintaining the same accuracy for symmetric trajectories. © 2009 IEEE.
Open Access
Behavioural analyses of quinine processing in choice, feeding and learning of larval drosophila
(2012) El-Keredy, A.; Schleyer, M.; König, C.; Ekim, A.; Gerber, B.
Gustatory stimuli can support both immediate reflexive behaviour, such as choice and feeding, and can drive internal reinforcement in associative learning. For larval Drosophila, we here provide a first systematic behavioural analysis of these functions with respect to quinine as a study case of a substance which humans report as "tasting bitter". We describe the dose-effect functions for these different kinds of behaviour and find that a half-maximal effect of quinine to suppress feeding needs substantially higher quinine concentrations (2.0 mM) than is the case for internal reinforcement (0.6 mM). Interestingly, in previous studies (Niewalda et al. 2008, Schipanski et al 2008) we had found the reverse for sodium chloride and fructose/sucrose, such that dose-effect functions for those tastants were shifted towards lower concentrations for feeding as compared to reinforcement, arguing that the differences in dose-effect function between these behaviours do not reflect artefacts of the types of assay used. The current results regarding quinine thus provide a starting point to investigate how the gustatory system is organized on the cellular and/or molecular level to result in different behavioural tuning curves towards a bitter tastant. © 2012 El-Keredy et al.
Open Access
Biosystems engineering of prokaryotes with tumor-killing capacities
(Bentham Science Publishers Ltd., 2016) Kalyoncu, E.; Olmez, T. T.; Ozkan, A. D.; Sarioglu, O. F.
Certain bacteria selectively attack tumor tissues and trigger tumor shrinkage by producing toxins and modulating the local immune system, but their clinical utility is limited because of the dangers posed by systemic infection. Genetic engineering can be used to minimize the risks associated with tumor-targeting pathogens, as well as to increase their efficiency in killing tumor cells. Advances in genetic circuit design have led to the development of bacterial strains with enhanced tumor-targeting capacities and the ability to secrete therapeutics, cytotoxic proteins and prodrug-cleaving enzymes, which allows their safe and effective use for cancer treatment. The present review details the recent advances in the design and application of these modified bacterial strains.
Open Access
The bonobo genome compared with the chimpanzee and human genomes
(2012) Prüfer, K.; Munch, K.; Hellmann I.; Akagi, K.; Miller J.R.; Walenz, B.; Koren, S.; Sutton G.; Kodira, C.; Winer, R.; Knight J.R.; Mullikin J.C.; Meader, S.J.; Ponting, C.P.; Lunter G.; Higashino, S.; Hobolth, A.; Dutheil J.; Karakoç, E.; Alkan, C.; Sajjadian, S.; Catacchio, C.R.; Ventura, M.; Marques-Bonet, T.; Eichler, E.E.; André, C.; Atencia, R.; Mugisha L.; Junhold J.; Patterson, N.; Siebauer, M.; Good J.M.; Fischer, A.; Ptak, S.E.; Lachmann, M.; Symer, D.E.; Mailund, T.; Schierup, M.H.; Andrés, A.M.; Kelso J.; Pääbo, S.
Two African apes are the closest living relatives of humans: the chimpanzee (Pan troglodytes) and the bonobo (Pan paniscus). Although they are similar in many respects, bonobos and chimpanzees differ strikingly in key social and sexual behaviours, and for some of these traits they show more similarity with humans than with each other. Here we report the sequencing and assembly of the bonobo genome to study its evolutionary relationship with the chimpanzee and human genomes. We find that more than three per cent of the human genome is more closely related to either the bonobo or the chimpanzee genome than these are to each other. These regions allow various aspects of the ancestry of the two ape species to be reconstructed. In addition, many of the regions that overlap genes may eventually help us understand the genetic basis of phenotypes that humans share with one of the two apes to the exclusion of the other. © 2012 Macmillan Publishers Limited. All rights reserved.
Open Access
Cd81 Interacts with the T Cell Receptor to Suppress Signaling
(2012) Cevik, S.I.; Keskin, N.; Belkaya, S.; Ozlu, M.I.; Deniz, E.; Tazebay, U.H.; Erman, B.
CD81 (TAPA-1) is a ubiquitously expressed tetraspanin protein identified as a component of the B lymphocyte receptor (BCR) and as a receptor for the Hepatitis C Virus. In an effort to identify trans-membrane proteins that interact with the T-cell antigen receptor (TCR), we performed a membrane yeast two hybrid screen and identified CD81 as an interactor of the CD3delta subunit of the TCR. We found that in the absence of CD81, in thymocytes from knockout mice, TCR engagement resulted in stronger signals. These results were recapitulated in T cell lines that express low levels of CD81 through shRNA mediated silencing. Increased signaling did not result from alterations in the levels of TCR on the surface of T lymphocytes. Although CD81 is not essential for normal T lymphocyte development, it plays an important role in regulating TCR and possibly pre-TCR signal transduction by controlling the strength of signaling. CD81 dependent alterations in thymocyte signaling are evident in increased CD5 expression on CD81 deficient double positive (DP) thymocytes. We conclude that CD81 interacts with the T cell receptor to suppress signaling. © 2012 Cevik et al.
Open Access
Chemical and topographical modification of PHBV surface to promote osteoblast alignment and confinement
(John Wiley & Sons, Inc., 2008) Kenar, H.; Kocabas, A.; Aydınlı, Atilla; Hasirci, V.
Proper cell attachment and distribution, and thus stronger association in vivo between a bone implant and native tissue will improve the success of the implant. In this study, the aim was to achieve promotion of attachment and uniform distribution of rat mesenchymal stem cell-derived osteoblasts by introducing chemical and topographical cues on poly(3-hydroxybutyrate-co-3- hydroxyvalerate) (PHBV) film surfaces. As the chemical cues, either alkaline phosphatase was covalently immobilized on the film surface to induce deposition of calcium phosphate minerals or fibrinogen was adsorbed to improve cell adhesion. Microgrooves and micropits were introduced on the film surface by negative replication of micropatterned Si wafers. Both chemical cues improved cell attachment and even distribution on the PHBV films, but Fb was more effective especially when combined with the micropatterns. Cell alignment (<10° deviation angle) parallel to chemically modified microgrooves (1, 3, or 8 μm groove width) and on 10 μm-thick Fb lines printed on the unpatterned films was achieved. The cells on unpatterned and 5 μm-deep micropitted films were distributed and oriented randomly. Results of this study proved that microtopographies on PHBV can improve osseointegration when combined with chemical cues, and that microgrooves and cell adhesive protein lines on PHBV can guide selective osteoblast adhesion and alignment.
Open Access
Chitosan scaffolds with BMP-6 loaded alginate microspheres for periodontal tissue engineering
(2012) Soran, Z.; Aydin, R.S.T.; Gumusderelioglu, M.
The aim of this study is to develop an effective growth factor releasing scaffold-microsphere system for promoting periodontal tissue engineering. Bone morphogenetic protein-6 (BMP-6)-loaded alginate microspheres in narrow size distribution were produced by optimising electrospraying conditions. The addition of these microspheres to chitosan gels produced a novel scaffold in which not only the pore sizes and interconnectivity were preserved, but also a controlled release vehicle was generated. Loading capacity was adjusted as 50ng or 100ng BMP-6 for each scaffold and the controlled release behaviour of BMP-6 from chitosan scaffolds was observed during seven days. Cell culture studies were carried out with rat mesenchymal stem cells derived from bone marrow in three groups; chitosan scaffolds, chitosan scaffolds containing BMP-6-loaded alginate microspheres and chitosan scaffolds with free BMP-6 in culture medium. Results showed that controlled delivery of BMP-6 from alginate microspheres has a significant effect on osteogenic differentiation. © 2012 Informa UK Ltd All rights reserved.
Open Access
Comparison of Au(III) and Ga(III) ions' binding to calf thymus DNA: Spectroscopic characterization and thermal analysis
(Humana Press Inc., 2014) Sarioglu O.F.; Tekiner-Gursacli, R.; Ozdemir, A.; Tekinay, T.
Metals have been studied as potential chemotherapeutic agents for cancer therapies due to their high reactivity toward a wide variety of substances. The characterization of metal ion-binding capacities is essential to understand the possible effects of metals on target biomolecules. In the present study, biochemical effects of Au(III) and Ga(III) ions on calf thymus DNA (ctDNA) were studied comparatively via bioanalytical, spectroscopic, and thermal methods. Briefly, UV-Vis absorbance spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy were utilized for spectroscopic characterization, and isothermal titration calorimetry (ITC) measurements were performed for thermal analysis. Our results reveal that both Au(III) and Ga(III) ions are capable of interacting with ctDNA, and Au(III) ions display a more favorable interaction and a higher binding affinity. ITC analyses indicate that the Au(III)-DNA interaction displays a binding affinity (Ka) around 1.43×106 M -1, while a Ka around 1.17×105 M -1 was observed for the Ga(III)-DNA binding. It was suggested that both metal ions are unlikely to change the structural B-conformation while interacting with ctDNA. © 2014 Springer Science+Business Media.
Open Access
Contact guidance enhances the quality of a tissue engineered corneal stroma
(John Wiley & Sons, Inc., 2008) Vrana, E.; Builles, N.; Hindie, M.; Damour O.; Aydınlı, Atilla; Hasirci, V.
Corneal stroma is a very complex structure, composed of 200 lamellae of oriented collagen fibers. This highly complex nature of cornea is known to be important for its transparency and mechanical integrity. Thus, an artificial cornea design has to take into account this complex structure. In this study, behavior of human corneal keratocytes on collagen films patterned with parallel channels was investigated. Keratocytes proliferated well on films and reached confluency after 7 days in the incubation medium. Nearly all of the cells responded to the patterns and were aligned in contrast to the cells on unpatterned surfaces. Collagen type I and keratan sulfate secreted by keratocytes on patterned films appeared to be aligned in the direction of the patterns. The films showed an intermediate degradation over the course of a month. On the whole, transparency of the films increased with degradation and decreased by the presence of the cells. The decrease was, however, low and transparency level was maintained on the patterned films while on the unpatterned films a sharp decrease in transparency was followed by an improvement. This was due to the more organized distribution of cells and the oriented secretion of extracellular matrix molecules on patterned collagen films. Thus, these results suggest that application of contact guidance in cornea tissue engineering may facilitate the remodeling process, hence decrease the rehabilitation period.
Open Access
Copy number variation of individual cattle genomes using next-generation sequencing
(2012) Bickhart, D.M.; Hou, Y.; Schroeder, S.G.; Alkan C.; Cardone, M.F.; Matukumalli L.K.; Song J.; Schnabel, R.D.; Ventura M.; Taylor J.F.; Garcia J.F.; Van Tassell, C.P.; Sonstegard, T.S.; Eichler, E. E.; Liu G.E.
Copy number variations (CNVs) affect a wide range of phenotypic traits; however, CNVs in or near segmental duplication regions are often intractable. Using a read depth approach based on next-generation sequencing, we examined genome - wide copy number differences among five taurine (three Angus, one Holstein, and one Hereford) and one indicine (Nelore) cattle. Within mapped chromosomal sequence, we identified 1265 CNV regions comprising ∼55.6-Mbp sequence-476 of which (~38%) have not previously been reported. We validated this sequence-based CNV call set with array comparative genomic hybridization (aCGH), quantitative PCR (qPCR), and fluorescent in situ hybridization (FISH), achieving a validation rate of 82% and a false positive rate of 8%. We further estimated absolute copy numbers for genomic segments and annotated genes in each individual. Surveys of the top 25 most variable genes revealed that the Nelore individual had the lowest copy numbers in 13 cases (∼52%, χ 2 test; P-value <0.05). In contrast, genes related to pathogen- and parasite-resistance, such as CATHL4 and ULBP17, were highly duplicated in the Nelore individual relative to the taurine cattle, while genes involved in lipid transport and metabolism, including APOL3 and FABP2, were highly duplicated in the beef breeds. These CNV regions also harbor genes like BPIFA2A (BSP30A) and WC1, suggesting that some CNVs may be associated with breed-specific differences in adaptation, health, and production traits. By providing the first individualized cattle CNV and segmental duplication maps and genome-wide gene copy number estimates, we enable future CNV studies into highly duplicated regions in the cattle genome. © 2012 by Cold Spring Harbor Laboratory Press.
Open Access
Design of a novel MRI compatible manipulator for image guided prostate interventions
(IEEE, 2005-02) Krieger, A.; Susil, R. C.; Ménard, C.; Coleman, J. A.; Fichtinger, G.; Atalar, Ergin; Whitcomb, L. L.
This paper reports a novel remotely actuated manipulator for access to prostate tissue under magnetic resonance imaging guidance (APT-MRI) device, designed for use in a standard high-field MRI scanner. The device provides three-dimensional MRI guided needle placement with millimeter accuracy under physician control. Procedures enabled by this device include MRI guided needle biopsy, fiducial marker placements, and therapy delivery. Its compact size allows for use in both standard cylindrical and open configuration MRI scanners. Preliminary in vivo canine experiments and first clinical trials are reported.
Open Access
Development of a thulium (Tm:YAP) laser system for brain tissue ablation
(2011) Bilici, T.; Mutlu, S.; Kalaycioglu H.; Kurt, A.; Sennaroglu, A.; Gulsoy, M.
In this study, a thulium (Tm:YAP) laser system was developed for brain surgery applications. As the Tm:YAP laser is a continuous-wave laser delivered via silica fibers, it would have great potential for stereotaxic neurosurgery with highest local absorption in the IR region. The laser system developed in this study allowed the user to set the power level, exposure time, and modulation parameters (pulse width and on-off cycles). The Tm:YAP laser beam (200-600 mW, 69-208 W/cm 2) was delivered from a distance of 2 mm to cortical and subcortical regions of ex-vivo Wistar rat brain tissue samples via a 200-μm-core optical fiber. The system performance, dosimetry study, and ablation characteristics of the Tm:YAP laser were tested at different power levels by maximizing the therapeutic effects and minimizing unwanted thermal side-effects. The coagulation and ablation diameters were measured under microscope. The maximum ablation efficiency (100 × ablation diameter/coagulation diameter) was obtained when the Tm:YAP laser system was operated at 200 mW for 10 s. At this laser dose, the ablation efficiency was found to be 71.4% and 58.7% for cortical and subcortical regions, respectively. The fiber-coupled Tm:YAP laser system in hence proposed for the delivery of photothermal therapies in medical applications. © 2011 Springer-Verlag London Ltd.
Open Access
Differences in the accumulation and distribution profile of heavy metals and metalloid between male and female crayfish (Astacus leptodactylus)
(2013) Tunca, E.; Ucuncu, E.; Ozkan, A.D.; Ulger, Z.E.; Cansizoǧlu, A.E.; Tekinay, T.
Concentrations of selected heavy metals and a metalloid were measured by ICP-MS in crayfish (Astacus leptodactylus) collected from Lake Hirfanli, Turkey. Aluminum (Al), chromium (52Cr, 53Cr), copper ( 63Cu, 65Cu), manganese (Mn), nickel (Ni) and arsenic (As) were measured in the exoskeleton, gills, hepatopancreas and abdominal muscle tissues of 60 crayfish of both genders. With the exception of Al, differences were determined between male and female cohorts for the accumulation trends of the above-mentioned elements in the four tissues. It was also noted that the accumulation rates of Ni and As were significantly lower in gill tissue of females compared to males and no significant difference was observed for Cu isotopes in female crayfish. Cluster Analysis (CA) recovered similar results for both genders, with links between accumulations of Ni and As being notable. Accumulation models were described separately for male and female crayfish using regression analysis, and are presented for models where R2 > 0.85. © 2013 Springer Science+Business Media New York.
Open Access
DNA methylation in eukaryotes
(TÜBİTAK, 1997) Pınarbaşı, Ergün
In prokaryotes, DNA methylation protects the bacteriaÕs DNA against degradation by restriction enzymes and corrects error in DNA replication by means of the mismatch repair system. In 1964, the first DNA methyltransferase was identified in E. coli. The avaiability of sequence-specific restriction enzymes and methyltransferases led to a major breakthrough in the field of molecular biology. In eukoryotes, DNA methylation appears to have a different role. It has been implicated in the control of several cellular processes, including differentiation, gene regulation and embryonic development. A series of discoveries over the past few years has generated new interest in DNA methylation. It has been found that in mice in particular DNA methyltransferase is essential for normal embryonic development. Cytosine methylation may also contribute to C-T transition mutations, accounting for about one-third of all somatic and germline mutations in humans.