Biyoloji Bölümü Koleksiyonu

Bu koleksiyon için kalıcı URI

https://hdl.handle.net/20.500.12428/2205

Listeleniyor 1 - 20 / 79

Effects of Different Doses of Lavender (Lavandula angustifolia) on Pubertal Development and Hormones in Male Syrian Hamsters (Mesocricetus auratus)
(Wiley, 2025) Balkan, Emine İnci; Kıral, İlke Ceren; Gündüz, Bülent
AIM:The effects of lavender, known for its calming effect, on the nervous system and reproductive system are being investigated. This study examines the development of male offspring exposed to different doses of lavender extract from the pregnancy period onwards. METHODS:Eight adult female and forty adult male offspring Syrian hamsters in a long photoperiod (16L) were assigned to four groups: the control group, the groups that received 50 mg/kg, the groups that received 100 mg/kg, and the groups that received 200 mg/kg lavender extract applied. Lavender extract was injected to the pregnant females in the experimental group during the last week of pregnancy and throughout the lactation period. From the 15th day after birth, male offspring were separated into groups of 5, with blood samples taken at midday and midnight. The doses were injected for 40 days. Weekly testis measurements were taken. Changes in serum leptin and testosterone hormones taken at the end of the experiment were determined. Testis histology was examined. RESULTS:The experimental groups showed no significant difference in leptin levels (p>0.05), although testosterone levels remained lower than in the control group (p<0.05). Testicular weights in the 100 mg/kg and 200 mg/kg groups were significantly lower than in the control group (p<0.05). Additionally, there was a decrease in Leydig cells and spermatogenesis in testicular histology in these groups. CONCLUSIONS:The physiological effects of plant extracts are not well studied, despite the fact that lavender is being used more and more in various fields. However, it is also known that higher dosages lower testosterone hormone levels and suppress the reproductive system in mature animals. This study evaluated the effects of various doses of lavender on the reproductive development of pubertal offspring from pregnancy onward, and for the first time, it was found to have negative impacts on development.
Discrepancies in the number of lines of arrested growth (LAG) in the tissues of the humerus and phalanx of sea turtles
(Springer Heidelberg, 2025) Sandık, Emre; Sönmez, Bektaş; Yalçın Özdilek, Şükran
Information on the age of vertebrate species such as sea turtles is crucial for planning management and conservation actions. The age of sea turtles has been estimated by skeletochronological analysis using skeletal growth marks in different bones. This study focused on the consistency of the number of visible lines of arrested growth (LAG) observed from the humerus and phalanx bone used for age estimation in Chelonia mydas and Caretta caretta. We collected 67 humeri and phalanges of C. mydas (n = 47) and C. caretta (n = 20) from Samanda & gbreve; beach, eastern Mediterranean in 2020-2022. LAG in the humerus and phalanx of the same individual were counted by two readers, and their consistency with each other was determined by percent agreement (PA), average percent error (APE), and coefficient of variation (CV). The significance of the difference between them was determined by the McNemar test. The mean number of visible LAG counted from the humerus is greater than the mean number of visible LAG counted from the phalanx, i.e., the humerus contains more growth marks than the phalanx. However, in individuals up to 15 LAG in C. mydas and 10 LAG in C. caretta, the mean number of visible LAG observed in both bone tissues is compatible. This was supported by the differences in the resorption rates calculated in both bones, indicating that the number of LAG lost due to resorption may also differ between these two bone types. It is recommended that the back calculation and/or correction factor applied for the humerus be avoided for the phalanx.
Investigation of the probiotic effects of Lactobacillus sakei 2-3 and Candida zeylanoides Y12-3 strains in rainbow trout (Oncorhynchus mykiss, Walbaum 1792)
(Springer, 2025) Taha, Mohanad Dheyaa; Didinen, Behire Işıl; Yılmaz, Sevdan; Gürkan, Mert; Kenanoğlu, Osman Nezih
This study aimed to assess individual and combined effects of candidate probiotic strains C. zeylanoides Y12-3 and L. sakei 2-3 on growth, hematological parameters, serum immunological parameters, serum biochemistry, histopathology, histomorphology, expression of immune and antioxidant enzyme genes, and disease resistance against L. garvieae in rainbow trout. The fish were fed four different feeds (control, L. sakei 2-3, C. zeylanoides Y12-3, and L. sakei 2-3 + C. zeylanoides Y12-3) for 60 days. At the end of the experiment, growth parameters, serum glucose levels, serum lysozyme activity, and expression of immune and antioxidant enzyme genes were significantly increased in the probiotic groups. Additionally, triglyceride levels decreased in the probiotic groups compared to the control group, whereas serum ALT levels did not change. The villus width and the number of goblet cells increased in the proximal intestines of the fish in C. zeylanoides and L. sakei + C. zeylanoides groups. L. sakei 2-3 showed higher superoxide anion production, expression of immune genes (IgM, IL-B1, lysozyme, TNF-alpha, HSP70) in the kidney, antioxidant enzyme genes (GPX, GST, SOD) in the liver compared to C. zeylanoides. TNF-alpha, HSP70), and antioxidant enzyme genes (GPX, GST, SOD) compared to C. zeylanoides. L. sakei and the combination of L. sakei + C. zeylanoides provided resistance to L. garvieae compared to the control group. However, C. zeylanoides was similar to the other two probiotic groups regarding disease resistance against L. garvieae. However, histopathological examinations revealed reversible changes in the proximal intestine, anterior kidney, and liver of fish in the C. zeylanoides and L. sakei + C. zeylanoides groups. Hence, future studies are still required to explore the effects of shorter-term use of the C. zeylanoides strain in rainbow trout to prevent undesirable effects on tissues. In brief, the findings, as mentioned above, showed that L. sakei 2-3 and C. zeylanoides Y12-3 could be potential probiotic candidates for use in rainbow trout farming. Moreover, the probiotic effects of both strains on different fish species should also be studied.
Prevention of Browning during in vitro Cultures of Verbascum scamandri
(World Researchers Associations, 2025) Cambaz, E.; Çördük, Nurşen
Browning, a common problem in plant tissue cultures, can hinder callus production and the synthesis of secondary metabolites. This study investigates browning in the in vitro callus culture of Verbascum scamandri, a plant species with significant medicinal potential. This study aims to evaluate the efficacy of various browning inhibitors. In the study, leaf explants from 15-week-old plants grown in vitro were used to investigate browning in callus cultures. Explants were cultured in MS basal medium supplemented with 3% sucrose, 0.7% phyto agar and 2 mg/L Kinetin, which was chosen for its high callus proliferation. Treatments included various concentrations (50, 100, 200 and 300 mg/L) and combinations of browning inhibitors (PEG, PVP, AA, CA, AC and AA+CA), as well as dark culture conditions. The density of browning and callus was recorded and calculated after 28 days including texture and color data of induced calli. According to the results, it was found that the most effective treatment for the prevention of browning is culturing in dark conditions. Additionally, it was observed that in this treatment, the density of callus induction was higher and the induced calli did not brown and had a compact texture. © 2025 World Researchers Associations. All rights reserved.
Melatonin-leptin interaction and obesity-related genes
(Trakya University, 2025) Gündüz, Bülent; Balkan, Emine İnci
Most living organisms have circadian clocks which maintain rhythm in internal cycles of behavior, physiology, and metabolism, allowing them to anticipate the earth's 24hour rotation. In mammals, circadian integration of metabolic systems optimizes energy gathering and usage across the light and dark cycles. Disruption of circadian rhythms may lead to metabolic dysfunctions such as obesity and obesity-related disorders. The molecular and hormonal mechanism behind obesity is mostly related to mRNA expressions in hypothalamus, and leptin, and melatonin hormone levels. In obesity and related disorders, the chronobiotic hormone melatonin regulates physiological functions such as energy metabolism, body fat, and reproduction by cross-interacting with leptin. Leptin signals satiety by inhibiting Neuropeptide Y/Agouti-Related Peptide (NPY/AgRP genes in hypothalamus and exerts its effects on food intake, body weight, and the reproductive system. In this review, the molecular and hormonal mechanisms behind obesity were discussed. © 2025 Gündüz & Balkan.
Effects of Altitude and Temperature on Erythrocyte Morphology of Emys orbicularis (Linnaeus, 1758) and Mauremys rivulata (Valenciennes, 18330)
(ABADER (Adıyaman Bilimsel Araştırmalar Derneği), 2021) Bayrakçı, Yusuf; Yenmiş, Melodi; Mermer, Ahmet; Tok, Cemal Varol; Ayaz, Dinçer
The decrease in erythrocyte size of animals live at high altitudes yields an evolutionary advantage to survive by providing adaptation to colder temperatures and low partial oxygen pressures. We examined the effect of geographical changes on the erythrocyte morphology of two terrapins, Emys orbicularis and Mauremys rivulata, and analyzed whether such erythrocyte characteristics as size and volume changed at high altitudes and different temperatures. We found out that the erythrocyte characteristics varied both within and between the populations. They varied depending on altitude for E. orbicularis and on temperature for M. rivulata. However, the erythrocyte characteristics were not correlated with the environmental parameters, except between sunshine duration and erythrocyte length, size, and nucleus volume for E. orbicularis. Yüksek rakımlarda yaşayan hayvanlarda eritrosit boyutlarındaki azalma, düşük sıcaklıklara ve düşük kısmi oksijen basıncına adaptasyon sağlayarak hayatta kalmalarına evrimsel bir avantaj kazandırmaktadır. Coğrafik değişikliklerin eritrosit morfolojisi üzerindeki etkilerini iki tatlısu kaplumbağası türü olan Emys orbicularis ve Mauremys rivulata’da inceledik ve boyut ve hacim gibi eritrosit özelliklerinin yüksek rakım ve farklı sıcaklıklarda değişip değişmediğini analiz ettik. Eritrosit özelliklerinin hem populasyon içerisinde hem de populasyonlar arasında farklılık gösterdiğini belirledik. E. orbicularis için yüksekliğe bağlı olarak, M. rivulata içinse sıcaklığa bağlı olarak değişiklik göstermektedir. Bununla birlikte, E. orbicularis için güneşlenme süresi ile eritrosit uzunluğu, büyüklüğü ve nukleus hacmi arasındaki korelasyon dışında, eritrosit özellikleri ile çevresel parametreler arasında korelasyon görülmemektedir.
Çevik Kurbağa (Rana dalmatina Bonaparte,1839) (Anura: Ranidae) Örneklerinde Yaş Tayini ve Bazı Büyüme Parametrelerinin İncelenmesi Üzerine Bir Ön Çalışma
(ABADER (Adıyaman Bilimsel Araştırmalar Derneği), 2021) Genç, Özge; Tok, Cemal Varol
In this study, a total of 16 Agile frog, Rana dalmatina species preserved in the ZDEU-COMU collection and collected from Çanakkale (4 ♂♂, 4 ♀♀) and Kırklareli (7♂♂, 1♀) were examined to estimate their age and the relationship between age and body size using the skeletochronology method. In addition, both femora and phalanx of the samples were evaluated together. Sexual maturity ages were found to be 2-3 in male and female individuals of both populations. The age ranges from 2-4 in males and 3-5 in females. According to this study, there was a positive correlation between length and age (r=0.740). In addition, no difference was observed in terms of LAG numbers compared to the age rings in the femora and Phalanx bones of the samples.
Fabrication and Characterization of Saffron Stamen Aqueous Extract Controlled Release System as Potential Topical Treatment of Thermal Burn Wounds
(John Wiley and Sons Inc, 2021) Özdemir, Burak; Pişkin, Mehmet Burçin; Gök, Bahar; Demir, Neslihan; Budama-Kılınç, Yasemin
In our study, we aimed the preparation of Saffron stamen aqueous extract (SSAE) loaded chitosan nanoparticles (CNPs) to be used topically for thermal burns. First, biological activity tests such as DNA binding, DNA cleavage and antibacterial activity were performed to determine the effectiveness of SSAE to be encapsulated. Additionally, a genotoxicity test was performed for the reliability of SSAE. Ionic gelation method was used for encapsulation, and SSAE-loaded CNPs were obtained. Average particle size, zeta potential, polydispersity index (PdI), morphology, and releasing kinetics of the SSAE-loaded CNPs and blank CNPs were determined. DNA binding showed that SSAE interacted with DNA electrostatically. It was determined that all doses of SSAE used in hydrolytic and oxidative DNA cleavage experiments cleave DNA. As a result of the Ames / Salmonella test, it was found that 1,25 mg SSAE was not genotoxic. Then, this concentration was used in nanoparticle synthesis. As a result of DLS analysis, it was determined that SSAE-loaded CNPs have an average size of 57.61±1.234 nm, 0.175±0.008 PdI, and +14±0.755 mV zeta potential. Encapsulation efficiency and loading capacity of SSAE-loaded CNPs calculated as 71.76 % and 2,64 % respectively. As a result of releasing kinetics, it was determined that 79.54 % of SSAE was released after 168 hours. Antibacterial results revealed that SSAE loaded CNPs were more effective against bacteria than blank SSAE.
The vertebrate biodiversity of Turkey
(Springer International Publishing, 2021) Karataş, Ahmet; Filiz, Halit; Erciyas-Yavuz, Kiraz; Özeren, Saniye Cevher; Tok, Cemal Varol
The present lists show that Turkish vertebrate fauna consists of 1728 species. Fish species form its half part (51.74%) with 530 marine and 402 inland fish species. However, the total number is 894, since 38 of them are living in salty, brackish, and freshwater. At the class level, Petromyzonti is represented by 4, Elasmobranchii by 65, Holocephali by 1, Actinopteri by 824, Amphibia by 36, Reptilia by 140, Aves by 485, and Mammalia by 173 species. A total number of 189 inland fish-1 Petromyzonti and 188 Actinopteri-13 amphibian, 20 reptile, and 5 mammal species are endemic to Turkey. The endemism rate out of the total vertebrate species is 13.14%. According to the given conservation status, at least five species are extinct, and 215 species are globally threatened.
COLL 490-Colloidal p(4-VP) particles and composites for biomedical application
(Amer Chemical Soc, 2009) Özay, Özgür; Aktaş, Nahit; Dülger, Başaran; Sılan, Coşkun; John, Vijay T.; Şahiner, Nurettin
[Anstract Not Available]
The Potential Error on the Quercus pyrenaica Honeydew Honey Identifications
(Sage Publications Inc, 2022) Battal, Fatih; Kaya, Serhat; Köseoğlu, Merve
[Anstract Not Available]
Porous and modified HA particles as potential drug delivery systems
(Elsevier Science Bv, 2012) Şahiner, Nurettin; Sılan, Coşkun; Sağbaş, Selin; Ilgın, Pınar; Bütün, Sultan; Erduğan, Hüseyin; Ayyala, Ramesh S.
Composite silica-hyaluronic acid (Si-HA) micro particles were synthesized, employing tetraethyl orthosilicate (TEOS) in the presence of linear HA and a crosslinker, divinyl sulfone (DVS) via a water-in-oil microemulsion polymerization technique. Porous HA (PHA) hydrogel particles were generated after removal of silica particles upon treatment of HA composites with hydrofluoric acid (FIF). Furthermore, HA particles were quaternized (QHA) by chemical modification using 3-chloro-2-hydroxypropyl trimethyl ammonium chloride as a quarternization agent. The size of HA based particles were ranged between 1.26 and 2.95 mu m. The PHA particles have a surface area of 2.7 m(2)/g confirmed by the surface area measurements. Modified HA particles were used in the absorption and release studies of two model drugs in PBS, trimethoprim (TMP) and sodium diclofenac (SDF) which are acidic and basic in nature, respectively. The ability to control the size, charge and porosity of the HA particles which showed almost linear drug release profiles. (C) 2012 Elsevier Inc. All rights reserved.
Evaluation of environmental degradation in the Karamenderes River in relation to anthropogenic stressors
(Parlar Scientific Publications (P S P), 2009) Koçum, Esra; Akgül, Füsun
Nutrient concentrations and phytoplankton biomass were monitored with reference to several anthropogenic pressures in the Karamenderes River (Canakkale, NW Turkey) and in its catchment through a seasonal sampling program of three sites. Both spatial and temporal variations in chl a, nitrate and nitrite and temporal variation in ammonium, phosphate and silicate were significant. Despite intense application of chemical fertilizers in agricultural areas within the catchment and elevated riverine nitrate concentrations phosphate levels were low, potentially keeping chl. a levels in oligotrophic range. Considering the important role of phosphorus in freshwater eutrophication and complex dynamics of phosphorus leaching from soil, the healthy functioning of this ecosystem critically depends on management plans that consider the long term risks associated with phosphate transfer from agricultural soils into the river.
COVID-19 Pandemisinde Korku, Algılanan Tehdit ve Kaygı: Bilişsel Kontrol/Esneklik ve Belirsizliğe Tahammülsüzlüğün Aracılık Rolü
(Turkiye Sinir Ve Ruh Sagligi Dernegi, 2024) Akgül, Özge; Önder Uzgan, Betül; Tetik, Melike; Aykaç, Cansu
Amaç: Bu çalışmada COVID-19 korkusu, algılanan COVID-19 tehdidi, kaygı, bilişsel kontrol/esneklik ve belirsizliğe tahammülsüzlük arasındaki ilişkilerin değerlendirilmesi amaçlanmıştır. Ayrıca bilişsel kontrol/esneklik ve belirsizliğe tahammülsüzlüğün aracı rolü araştırılmıştır. ABSTRACT Fear, Perceived Threat, and Anxiety During COVID-19 Pandemic: The Mediating Role of Cognitive Control/Flexibility and Intolerance of Uncertainty Yöntem: 18-55 yaş arası 224 gönüllü çalışmaya dahil edilmiştir. Tüm katılımcılara bilişsel kontrol ve esneklik ölçeği, belirsizliğe tahammülsüzlük ölçeği, COVID-19 korkusu ölçeği, algılanan COVID-19 tehdit formu ve Beck kaygı ölçekleri çevrimiçi bir ortam aracılığıyla uygulanmıştır. Bu bağlamda verilere, Pearson korelasyon analizi, lineer regresyon ve aracılık analizleri uygulanmıştır. Bulgular: Bilişsel kontrol ve esneklik, Belirsizliğe Tahammülsüzlük, Beck Anksiyete, COVID-19 korkusu, Algılanan COVID-19 Tehdidi değişkenleri arasında istatistiksel olarak anlamlı ilişkiler saptanmıştır (p<0,01). Lineer regresyon analizi; Beck kaygı ölçeği, belirsizliğe tahammülsüzlük ve bilişsel kontrol/esneklik ölçek puanlarının COVID-19 korkusunu ve algılanan COVID-19 tehdidini önemli ölçüde yordadığını göstermiştir (p<0,001). Ayrıca aracılık analizleri belirsizliğe tahammülsüzlüğün ve bilişsel kontrol/esnekliğin, kaygı ile algılanan COVID-19 tehdidi arasında aracı faktörler olduğunu ortaya koymuştur (p<0,01) Sonuç: COVID-19 korkusu ile tehdit algısı, kaygı, belirsizliğe tahammülsüzlük ve bilişsel kontrol mekanizmaları arasında ilişki bulunmaktadır. Bu doğrultuda bireylerin ruh sağlığı iyiliğinin artırılması açısından bilişsel kontrol/esneklik ve belirsizliğe tahammülsüzlüğün etkisinin bireyler üzerinde çalışılabilmesi, pandeminin psikolojik belirtilerini hafifletecek profesyonel desteğin yanında sunulabilir.
One-step fabrication of biocompatible carboxymethyl cellulose polymeric particles for drug delivery systems
(Elsevier Sci Ltd, 2011) Bütün, Sultan; İnce, Fatma Gül; Erduğan, Hüseyin; Şahiner, Nurettin
Carboxymethyl cellulose (CMC) particles were synthesized in one step employing inverse micelle microemulsion polymerization using divinyl sulfone as crosslinking agent. These synthesized particles were further modified and demonstrated as drug delivery system. Acyclovir was chosen as the model drug. The synthesized CMC particles were made magnetic responsive by encasing independently prepared magnetic ferrite particles (Fe(3)O(4)) in CMC polymeric particles during the synthesis as magnetic-CMC (m-CMC). The particles were characterized by using dynamic light scattering (DLS), zeta potential measurements (ZP). FT-IR spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analyzer (TGA). The synthesized particles have wide size distribution ranging from 100 to 10,000 nm. The further modification of CMC and magnetic Fe(3)O(4) containing CMC polymeric particles crosslinked at different ratios was performed successfully by introducing new functional groups to the CMC networks. It was determined that these particles obtained from the natural CMC polymers have a potential range of application as drug and targeted drug delivery system in biomedical field. (C) 2011 Elsevier Ltd. All rights reserved.
Phytoplankton stoichiometry reflects the variation in nutrient concentrations and ratios in a nitrogen-enriched coastal lagoon
(Taylor & Francis Ltd, 2017) Sütçü, Ayşe; Koçum, Esra
Human impacts on carbon, nitrogen and phosphorus cycles have differentially increased the flux of C, N and P to the coastal zone creating an altered environment with respect to nutrient stoichiometry for production and transfer of organic matter. Such changes can be more pronounced in closed and semi-enclosed ecosystems. The spatio-temporal variability in chl a, phytoplankton C, N and P content and stoichiometry were measured along with nutrients to reveal relations between them in a coastal lagoon. High nitrate concentrations and low availability of phosphate produced skewed nutrient stoichiometry that reflected itself in the large deviations of PC:PN and PN:PP from their corresponding Redfield ratios while the dynamic nature of fluctuations in nutrient concentrations led to wide variations in phytoplankton C, N and P content and in their ratios. The findings of the study provide insights into the possible alterations in phytoplankton stoichiometry in similar ecosystems receiving high inputs which is not balanced with phosphorus and/or where P-reduction is the mode of eutrophication control as both can produce skewed nutrient stoichiometry.
Monitoring of phytoplankton biomass and nutrients in a polluted stream
(Inderscience Enterprises Ltd, 2007) Koçum, Esra; Dursun, Onur
The spatial and temporal variations in the concentrations of nutrients (NH4+, NO2-, PO43-, SiO3-) and chlorophyll a were monitored simultaneously in a slow-flowing watercourse (Saricay Stream, Turkey), which runs in a rural-urban gradient. Chlorophyll a concentrations ranged between 0.044 mu g l(-1) and 206.15 mu g l(-1) and, in general, the higher concentrations of chlorophyll a and ammonium were measured downstream of the raw sewage outfalls. Nitrate was by far the most abundant form of inorganic nitrogen, and its concentration ranged between 411.71 mu M and 87.251 mu M. Silicates and phosphates were always potentially limiting to biomass relative to nitrogen. Agricultural run-off and point discharges from urban sources greatly affected the chemical composition of the water in the Saricay Stream and drove the system towards eutrophication.
Analysis of Variations in Phytoplankton Community Size-Structure along a Coastal Trophic Gradient
(Coastal Education & Research Foundation, 2014) Koçum, Esra; Sütçü, Ayşe
The phytoplankton community size structure is a significant factor in the ecological and biogeochemical functioning of marine ecosystems. Various environmental factors, including nutrients, can cause variations in the size structure of phytoplankton community, ultimately determining the potential for downward carbon transport and productivity in marine ecosystems. In the present study, microscale spatial variation in phytoplankton size structure was investigated at two coastal stations having different nutrient environments. The variation in phytoplankton size structure was characterized by a significantly (p < 0.05) higher contribution of larger cells and diminishing abundance of picoplankton under increasing nutrient concentrations observed at both sites, although at different threshold unfractionated phytoplankton chlorophyll a biomass levels. The average percent contributions of picoplankton to total biomass were 30.02 and 19.07% at less enriched site I and at enriched site II, respectively. Thus, we concluded that the variation in phytoplankton size structure was led by the factors that regulated the contribution of large phytoplankton cells; that is, the dominance of picoplankton was only possible when nutrient concentrations precluded accumulation of the larger size classes in the phytoplankton community.
Regulation of phytoplankton primary production along a hypernutrified estuary
(Inter-Research, 2002) Koçum, Esra; Nedwell, DB; Underwood, GJC
The influence of nutrients on algal biomass and primary production was investigated in the estuary of the River Colne, a turbid hypernutrified estuary on the east coast of England. Different approaches were used to examine nutrient regulation of both algal biomass formation and algal primary production in the Colne Estuary. Stoichiometric nutrient ratios indicated that silicate was always potentially limiting to biomass relative to nitrogen and phosphorus, and there were only small numbers of diatoms present in the phytoplankton community. Addition of silicate stimulated diatom growth. At the freshwater end of the estuary, low N:P ratios resulting from the input of effluent from sewage treatment works with high P levels created a potential for N limitation of algal biomass production. The N:P ratios at the seaward end of the estuary were much higher, suggesting greater potential for P limitation of algal biomass formation. This is the reverse of the usual assumption for P limitation in freshwater and N limitation in seawater. Nutrient depletion experiments corroborated the indication of greater N limitation of phytoplankton in the upper estuary. Ammonium rather than nitrate was used first by the algae despite being at much lower concentrations than nitrate. F-ratios measured with N-15 ammonium or nitrate showed that, except on 1 occasion in the upper estuary, > 95 % of the N uptake was from ammonium. Despite the high nutrient concentrations in the estuary, algal productivity was strongly limited by light availability. This, combined with the freshwater flushing time for the Colne Estuary (14 d), probably meant that depletion of nutrients and imposition of nutrient limitation on algal growth would only occur outside the estuary in the coastal zone.
Effects of subchronic exposure to zinc nanoparticles on tissue accumulation, serum biochemistry, and histopathological changes in tilapia (Oreochromis niloticus)
(Wiley, 2017) Kaya, Hasan; Duysak, Müge; Akbulut, Mehmet; Yılmaz, Sevdan; Gürkan, Mert; Arslan, Zikri; Demir, Veysel
Zinc nanoparticles (ZnNPs) are among the least investigated NPs and thus their toxicological effects are not known. In this study, tilapia (Oreochromis niloticus) were exposed to 1 and 10 mg/L suspensions of small size (SS, 40-60 nm) and large size (LS, 80-100 nm) ZnNPs for 14 days under semi-static conditions. Total Zn levels in the intestine, liver, kidney, gill, muscle tissue, and brain were measured. Blood serum glucose (GLU), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and lactate dehydrogenase (LDH) were examined to elucidate the physiological disturbances induced by ZnNPs. Organ pathologies were examined for the gills, liver, and kidney to identify injuries associated with exposure. Significant accumulation was observed in the order of intestine, liver, kidney, and gills. Zn levels exhibited time- and concentration-dependent increase in the organs. Accumulation in kidney was also dependent on particle size; NPs SS-ZnNPs were trapped more effectively than LS-ZnNPs. No significant accumulation occurred in the brain (p>0.05) while Zn levels in muscle tissue increased only marginally (p0.05). Significant disturbances were noted in serum GOT and LDH (p<0.05). The GPT levels fluctuated and were not statistically different from those of controls (p>0.05). Histopathological tubular deformations and mononuclear cell infiltrations were observed in kidney sections. In addition, an increase in melano-macrophage aggregation intensity was identified on the 7th day in treatments exposed to LS-ZnNPs. Mononuclear cell infiltrations were identified in liver sections for all treatments. Both ZnNPs caused basal hyperplasia in gill sections. Fusions appeared in the gills after the 7th day in fish treated with 10 mg/L suspensions of SS-ZnNPs. In addition, separations in the secondary lamella epithelia were observed. The results indicated that exposure to ZnNPs could lead to disturbances in blood biochemistry and cause histopathological injuries in the tissues of O. niloticus. (c) 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1213-1225, 2017.

Güncel Gönderiler