A new bio-active asymmetric-Schiff base: synthesis and evaluation of calf thymus DNA interaction, topoisomerase IIα inhibition, in vitro antiproliferative activity, SEM analysis and molecular docking studies.

In this paper, the asymmetric-Schiff base 2-(4-(2-hydroxybenzylideneamino)benzylideneamino)benzoic acid (SB-2) was newly synthesized and characterized by various spectroscopic methods. The interaction of SB-2 with calf thymus DNA was investigated by UV-vis, fluorescence spectroscopy and molecular docking methods. It was determined that SB-2 effectively binds to DNA via the intercalation mode. DNA electrophoretic mobility experiments displayed that topoisomerase IIα could not cleave pBR322 plasmid DNA in the presence of SB-2, confirming that the Schiff base acts as a topo II suppressor. In the molecular docking studies, SB-2 was found to show an affinity for both the DNA-topoisomerase IIα complex and the DNA. In vitro antiproliferative activity of SB-2 was screened against HT-29 (colorectal) and HeLa (cervical) human tumor cell lines by MTT assay. SB-2 diminished the cell viability in a concentration- and incubation time-dependent manner. The ability of SB-2 to measure DNA damage in tumor cells was evaluated with cytokinesis-block micronucleus assay after incubation 24 h and 48 h. Light and scanning electron microscopy experiments of tumor cells demonstrated an incubation time-dependent increase in the proportion of apoptotic cells (nuclear condensation and apoptotic bodies) suggesting that autophagy and apoptosis play a role in the death of cells. Based on the obtained results, it may be considered that SB-2 is a candidate for DNA-targeting antitumor drug.Communicated by Ramaswamy H. Sarma.

Escherichia coli Enumeration in a Capillary-Driven Microfluidic Chip with SERS.

Pathogen detection is still a challenging issue for public health, especially in food products. A selective preconcentration step is also necessary if the target pathogen concentration is very low or if the sample volume is limited in the analysis. Plate counting (24-48 h) methods should be replaced by novel biosensor systems as an alternative reliable pathogen detection technique. The usage of a capillary-driven microfluidic chip is an alternative method for pathogen detection, with the combination of surface-enhanced Raman scattering (SERS) measurements. Here, we constructed microchambers with capillary microchannels to provide nanoparticle-pathogen transportation from one chamber to the other. Escherichia coli (E. coli) was selected as a model pathogen and specific antibody-modified magnetic nanoparticles (MNPs) as a capture probe in a complex milk matrix. MNPs that captured E. coli were transferred in a capillary-driven microfluidic chip consisting of four chambers, and 4-aminothiophenol (4-ATP)-labelled gold nanorods (Au NRs) were used as the Raman probe in the capillary-driven microfluidic chip. The MNPs provided immunomagnetic (IMS) separation and preconcentration of analytes from the sample matrix and then, 4-ATP-labelled Au NRs provided an SERS response by forming sandwich immunoassay structures in the last chamber of the capillary-driven microfluidic chip. The developed SERS-based method could detect 101-107 cfu/mL of E. coli with the total analysis time of less than 60 min. Selectivity of the developed method was also tested by using Salmonella enteritidis (S. enteritidis) and Staphylococcus aureus (S. aureus) as analytes, and very weak signals were observed.

Construction of a sensitive and selective plasmonic biosensor for prostate specific antigen by combining magnetic molecularly-imprinted polymer and surface-enhanced Raman spectroscopy.

Selective and sensitive detection of cancer biomarkers in serum samples is critical for early diagnosis of cancer. Prostate specific antigen is an important biomarker of prostate cancer, which ranks high among cancer-related deaths of men over 50 years old. Herein, a novel analytical method was introduced for detection of PSA by combining high selectivity of molecularly-imprinted polymers and high sensitivity of surface-enhanced Raman spectroscopy (SERS). Firstly, magnetic nanoparticles were grafted with an imprinted layer by using tannic acid as a functional monomer, diethylenetriamine as a cross-linker and prostate specific antigen as a template molecule. Detailed surface characterization and re-binding experiment results indicated that the imprinting of the antigen was successful with an imprinting factor of 5.58. The prepared magnetic molecularly imprinted polymers (MMIPs) were used as an antibody-free capture probe and labeled with gold nanoparticles that were modified with anti-PSA and a Raman reporter, namely 5,5'-dithiobis-(2-nitrobenzoic acid). Thus, a plasmonic structure (sandwich complex) was formed between MMIP and the SERS label. The limit of detection and limit of quantification of the designed sensor were 0.9 pg/mL and 3.2 pg/mL, respectively. The sensor also showed high recovery rates (98.0-100.1% for healthy person and 99.0-101.3% for patient) with low standard deviations (less than 4.3% for healthy person and less than 3.3% for patient) for PSA in serum samples. Compared with the traditional immunoassays, the proposed method has several advantages like low cost, reduced detection procedure, fast response, high sensitivity and selectivity. It is believed that the proposed method can be potentially used for selective and sensitive determination of tumor marker of prostate cancer in clinical applications.

Accessory glands of male reproductive system in Pseudochorthippus parallelus parallelus (Zetterstedt, 1821) (Orthoptera: Acrididae): A light and electron microscopic study.

The accessory glands of male reproductive system in insects play a significant role in the reproduction process by protecting sperm in spermatheca, preventing female to accept other males after mating and stimulating oviposition. The number, structure, and arrangement of the tubules of accessory glands can change from species to species. In this study, the accessory glands belonging the male reproductive system in Pseudochorthippus parallelus parallelus (Zetterstedt, 1821) (Orthoptera, Acrididae) were examined with stereomicroscope, light microscope, scanning (SEM), and transmission (TEM) electron microscopes at Gazi University, Faculty of Science in 2017-2019. P. parallelus parallelus is a widespread species that is located at the extending areas from Italy to the Northern Europe and also in Turkey. The accessory glands of P. parallelus parallelus' male reproductive system are composed of about 10 tubules. The tubules can be classified into two groups according to the thickness of their muscle tissues. Both groups have single layered epithelial cells with mitochondria, well-developed endoplasmic reticulum, spherical nucleus with electron dense chromatin, secretory vesicles and multivesicular bodies in their cytoplasm. In addition, apocrine type secretion is seen in epithelial cells.

Tracing Size and Surface Chemistry-Dependent Endosomal Uptake of Gold Nanoparticles Using Surface-Enhanced Raman Scattering.

Surface-enhanced Raman scattering (SERS)-based single-cell analysis is an emerging approach to obtain molecular level information from molecular dynamics in a living cell. In this study, endosomal biochemical dynamics was investigated based on size and surface chemistry-dependent uptake of gold nanoparticles (AuNPs) on single cells over time using SERS. MDA-MB-231 breast cancer cells were exposed to 13 and 50 nm AuNPs and their polyadenine oligonucleotide-modified forms by controlling the order and combination of AuNPs. The average spectra obtained from 20 single cells were analyzed to study the nature of the biochemical species or processes taking place on the AuNP surfaces. The spectral changes, especially from proteins and lipids of endosomal vesicles, were observed depending on the size, surface chemistry, and combination as well as the duration of the AuNP treatment. The results demonstrate that SERS spectra are sensitive to trace biochemical changes not only the size, surface chemistry, and aggregation status of AuNPs but also the endosomal maturation steps over time, which can be simple and fast way for understanding the AuNP behavior in single cell and useful for the assisting and controlling of AuNP-based gene or drug delivery applications.

Surface-enhanced Raman spectroscopy based 3D spheroid culture for drug discovery studies.

Three-dimensional (3D) spheroid cultures are more realistic tissue mimicking structures for drug discovery studies. However, analysis of 3D spheroid cultures is a challenge task because available techniques are destructive, which results with the loss of biochemical information confined in a spatial arrangement inside of spheroids. In this study, a surface-enhanced Raman scattering (SERS) based non-destructive approach is reported to study 3D cultures. Since the technique uses gold nanoparticles (AuNPs) as SERS substrates, the cells treated with AuNPs are used for the preparation of spheroids. Since SERS spectra originate from molecular species near AuNPs and their aggregates in endolysosomes, the obtained spectral information can provide significant level of information about biomolecular processes taking place in endolysosomes and dependently in cells. The performance of the approach is evaluated by monitoring the spectral changes upon external stimuli with Doxorubicin (Dox) and Paclitaxel (Pac). A layer-by-layer depth-scan SERS analysis of Dox and Pac treated spheroids reveals the spectral changes at around 555 cm-1 and 675 cm-1 originating from cholesterol and guanine, respectively, compared to control (un-treated) spheroids. Higher spectral variation is observed from the inner to the outer layers of spheroid surface. The results demonstrate that the approach can be used to monitor the intracellular responses, which are in correlation with endolysosomal pathway according to the depth-layers of intact and living 3D spheroids upon external stimuli.

Morphological and histological structure of the male reproductive system of the water strider Gerris lacustris (Linnaeus 1758) (Gerridae, Heteroptera).

This work presents the male reproductive system morphology and histology of the water strider Gerris lacustris (Linnaeus 1758) (Gerridae, Heteroptera) using light microscopy and scanning electron microscopy. The male reproductive system of G. lacustris comprise of a pair of testes, two vasa deferentia, two seminal vesicles, an ejaculatory duct. There is no bulbus ejaculatorius and the long vas deferantia uniting to form a simple ductus ejaculatorius which is connected to the aedeagus. The testes are white colored and this cylindiric-shaped structure lies along genital abdominal segment. The testicular follicles have three different development zones (growth zone, maturation zone, differentiation zone). Each testis has two follicles, which are not lined by a common peritoneal sheath and involving many cysts arranged in a progressive order of maturation from the distal to the proximal region; spermiogenesis occurs in mature males, finishing with the organization of sperm bundles. The testes are connected to the seminal vesicles, specialized sperm storage places, by the vas deferentia.

Tamoxifen-Related Thrombosis: An Experimental Study in Rat Venous Microvascular Anastomosis Model.

Tamoxifen is an estrogen receptor modulator and has been shown to increase risk for microvascular flap complications. This study aimed to investigate the clinical and histopathological effects of tamoxifen use in venous microvascular anastomosis model in rats. The role of vitamin E combination therapy and discontinuing tamoxifen therapy preoperatively were also evaluated.Forty rats were equally divided into 4 groups as follows: group 1 was given saline by oral gavage, group 2 was given tamoxifen citrate, group 3 was given tamoxifen citrate and vitamin E, and in group 4, tamoxifen citrate was given everyday except between days 12 and 16. In each group, femoral veins were dissected in each side and end-to-end anastomosis was performed in one side. Clinical and histopathological evaluations were performed. The ratio of total endothelial area to total vein area in a cross-sectional view of the vein was evaluated and compared.All veins with anastomosis in postoperative 15 minutes were found to be patent. In postoperative 1 week in groups 1 to 4, visible thrombus were present in 1, 3, 2, and 3 samples, respectively. Vitamin E group showed similar histopathological findings with control group. The ratio of endothelial layer to total vein cross-sectional area was increased in groups 2 and 4 in all samples. The increase was statistically significant between groups 2NA and 3NA (P = 0.023) and 2A and 1A (P = 0.006).Chronic tamoxifen consumption in the presence of anastomosis have led to prominent endothelial proliferation in rat femoral veins. Vitamin E combination therapy reversed this endothelial proliferation and should be focused in future studies.

Structural and ultrastructural features of the Malpighian tubules of Dolycoris baccarum (Linnaeus 1758), (Heteroptera: Pentatomidae).

The morphology and ultrastructure of the Malpighian tubules of Dolycoris baccarum were analyzed by scanning (SEM) and transmission (TEM) electron microscopy in order to determine their functional organization. The Malpighian tubules are compared with similar structures of other insects based on cell structure and functional organization. The Malpighian tubules of D. baccarum extend from the midgut-hindgut region of the digestive tract. The Malpighian tubules are divided into two regions: the proximal segment is short and flattened and the distal segment is long, stringy in shape and free in hemolymph. The tubules are generally long and narrow. There is a large number of trachea around the tubules. They consist of a single layer of epithelial cells. It is observed in the TEM observation that the epithelial cells have numerous microvilli at the apical side of the cells. At the basal side of the cells, there is a great number of membrane foldings and mitochondria among them. Besides some spherites, mitochondria, lysosome-like bodies, and large or small granules can be distinguished in the cells. With this study, we aimed to demonstrate the ultrastructure of the Malpighian tubules of D. baccarum and differences or similarities with other species.

Gold-Coated Iron Composite Nanospheres Targeted the Detection of Escherichia coli.

We report the preparation and characterization of spherical core-shell structured Fe3O4-Au magnetic nanoparticles, modified with two component self-assembled monolayers (SAMs) consisting of 3-mercaptophenylboronic acid (3-MBA) and 1-decanethiol (1-DT). The rapid and room temperature synthesis of magnetic nanoparticles was achieved using the hydroxylamine reduction of HAuCl4 on the surface of ethylenediaminetetraacetic acid (EDTA)-immobilized iron (magnetite Fe3O4) nanoparticles in the presence of an aqueous solution of hexadecyltrimetylammonium bromide (CTAB) as a dispersant. The reduction of gold on the surface of Fe3O4 nanoparticles exhibits a uniform, highly stable, and narrow particle size distribution of Fe3O4-Au nanoparticles with an average diameter of 9 ± 2 nm. The saturation magnetization value for the resulting nanoparticles was found to be 15 emu/g at 298 K. Subsequent surface modification with SAMs against glucoside moieties on the surface of bacteria provided effective magnetic separation. Comparison of the bacteria capturing efficiency, by means of different molecular recognition agents 3-MBA, 1-DT and the mixed monolayer of 3-MBA and 1-DT was presented. The best capturing efficiency of E. coli was achieved with the mixed monolayer of 3-MBA and 1-DT-modified nanoparticles. Molecular specificity and selectivity were also demonstrated by comparing the surface-enhanced Raman scattering (SERS) spectrum of E. coli-nanoparticle conjugates with bacterial growth media.

Influence of gastrointestinal system conditions on adhesion of exopolysaccharide-producing Lactobacillus delbrueckii subsp. bulgaricus strains to caco-2 cells

This study aimed to assess the transit tolerance of potential probiotic dairy Lactobacillus strains in human uppergastrointestinal tract in vitro, and to evaluate the effect of EPS production on the viability and adhesion of these strains. Survival and adhesion of two exopolysaccharide (EPS)-producing L. delbrueckii subsp. bulgaricus strains (B3 and B2) and E. coli ATCC11229 were assessed after the exposure of different pH (gastric juice) and gastric plus pancreatic juice challenges. In the artificial gastric juice (pH 2), both the viability of the strain B3 and B2 was decreased. Artificial juice treatments significantly reduced the adhesion to caco-2 cells (P< 0.05). High EPS-producing B3 survived better in the adverse gastrointestinal conditions and showed better ability of adhesion to Caco-2 cells when assessed for competition with E. coli ATCC 11229 compared to low EPS-producing B2. This investigation showed that EPS production could be affected or be involved in the viability, adherence and competition of L. delbrueckii subsp. bulgaricus strains and support the potential of B3 strain for development of new probiotic products.

Cadmium(II) sequestration characteristics by two isolates of Synechocystis sp. in terms of exopolysaccharide (EPS) production and monomer composition.

We investigated cadmium(II) resistance and its association with exopolysaccharide (EPS) production in cyanobacteria. Increased EPS production was associated with Cd(II) resistance. The most resistant isolate, Synechocystis sp. BASO670, secreted the greatest amount of EPS (548 mg/L). EPS production by Synechocystis sp. BASO670 and Synechocystis sp. BASO672 was increased following exposure to 15 and 35 ppm Cd(II). Monomer composition of EPS belonging to each isolate was changed after Cd(II) treatment. Uronic acid contents of Cd(II) treated cells were higher than control cells of each isolate. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis confirmed that a considerable amount of metals had precipitated on the cell surface. Fourier transform infrared (FT-IR) spectrum analysis of EPSs belonging to both isolates indicated the presence of C-H and C-O group, which may serve as binding sites for divalent cations.

Toxicity and uptake of iron ions by Synechocystis sp. E35 isolated from Kucukcekmece Lagoon, Istanbul.

The study demonstrates the potential of using unicellular cyanobacteria species, isolated from Kucukcekmece Lake, Turkey, for biological Iron removal from aqueous solutions. EC(50) at 96h was estimated to be 13.92 mg/L for Synechocystis sp. E35. The optimum pH value and incubation temperature for the resistant isolate were 7.0 and 23 degrees C, respectively. The Iron biosorption/bioaccumulation by Synechocystis sp. E35 was evaluated by fractionating the Fe content as the remaining metal in supernatant, the adsorbed metal on the cell surface and the intracellular accumulation. Synechocystis sp. E35 adsorbed appreciable quantities of Iron ions on the cell surface within 5 min. Metal ions were adsorbed onto the surface of cells followed by active uptake resulting in the transportation of the metal ions across the cell membrane and into the cytoplasm. Intracellular metal uptake increased with increasing metal concentrations from 10 to 15 mg/L. Extracellular polysaccharides (EPSs) were clearly seen in SEM images of Synechocystis sp. E35 grown at a 10mg/L metal concentration. EPS region was analyzed with Energy Dispersive X-Ray Analysis (EDXA) and the SEM images further confirmed our experimental observations about the Iron biosorption/bioaccumulation mechanism.

Effects of endosulfan on Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae) larvae.

Thaumetopoea pityocampa larvae are very harmful to pines and they also cause allergic reactions in men and animals. In this study, different concentrations of endosulfan were administered to T. pityocampa larvae via pine needles which were prepared by the dipping method. The data obtained were statistically evaluated using probit analysis and a LC(50/48 hrs) value for T. pityocampa larvae found to be 1.679 mg/l. Also, 12, 24, 36 and 48 hrs after 1.679 mg/1 endosulfan treatment, ultrastructural changes in the midgut epithelium of T. pityocampa were investigated. No pathological changes were observed after 12 hrs, swelling and vacuolization of mitochondria and dilation ofendoplasmic reticulum after 24 hrs, swelling ofmitochondria and breaking of mitochondrial cristae and dissolving of nucleoplasm after 36 hrs, finally large vacuoles in the midgut epithelium cells were observed after 48 hrs.