Transvection at the Eyes Absent Gene of Drosophila

The Drosophila eyes absent (eya) gene is required for survival and differentiation of eye progenitor cells. Loss of gene function in the eye results in reduction or absence of the adult compound eye. Certain combinations of eya alleles undergo partial complementation, with dramatic restoration of eye size. This interaction is sensitive to the relative positions of the two alleles in the genome; rearrangements predicted to disrupt pairing of chromosomal homologs in the eya region disrupt complementation. Ten X-ray-induced rearrangements that suppress the interaction obey the same general rules as those tha disrupt transvection at the bithorax complex and the decapentaplegic gene. Moreover, like transvection in those cases, the interaction at eya depends on the presence of normal zeste function. The discovery of transvection at eya suggests that transvection interactions of this type may be more prevalent than generally thought.     

Development of the Drosophila retina,a neurocrystalline lattice

Pattern formation in the Drosophila retina proceeds by the recruitment of cells, along a morphogenetic front, into a lattice. At the advancing front, marked by a dorso-ventral furrow in the eye imaginal disc, cells are organized into ommatidial precursors, each containing cells destined to become photoreceptors 2, 3, 4, 5, and 8. Behind the front, a mitotic wave produces photoreceptors 1, 6, and 7, plus the remaining cells needed to complete the ommatidia. During the third larval instar, the front sweeps anteriorly across the eye disc, leaving a highly ordered pattern in its wake. Preceding the dorso-ventral furrow is a groove that bisects the eye disc into dorsal and ventral halves and presumably plays a role in establishing the equatorial symmetry line. Cell lineage plays little role in pattern formation in the eye. Genetic mosaics show that the cells of each ommatidium are not derived from a single mother cell; the cells appear to be recruited at random at the morphogenetic front. Similarly, the mirror symmetry above and below the equator is not established by a clonal mechanism; a single clone can contribute cells to ommatidia on both sides of the equator.     

Development of Vaccine Prototype Against Zika Virus Disease of Peptide-Loaded PLGA Nanoparticles and Evaluation of Cytotoxicity

Zika virus has recently evolved from an obscure mosquito-borne pathogen to an international public health concern. People with Zika virus disease can have indications including mild fever, skin rash, conjunctivitis, muscle pain, malaise or headache. Effective vaccines are needed for controlling and preventing the disease. In the current study, we aim to design the substructure for vaccine against Zika virus by forming antigenic peptide epitope of the disease. Zika peptide loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles have been fabricated in the present work as a potential artificial vaccine. UV and FT-IR Spectrophotometers and ZetaSizer were used for studying the nanoparticles, and Scanning Electron Microscope was used for morphological examination. The nanoparticles (NPs) yield, encapsulation efficiency, the peptide loading capacity were determined and in vitro release of the peptide was studied. Cytotoxic effects of the various concentrations of Zika peptide, blank PLGA nanoparticles and Zika peptide loaded PLGA nanoparticles on ECV304 human epithelial cells were determined via MTT assay. The present paper could be considered as one of the important steps in the use of nanoparticles for constructing the new generation of vaccination systems.

     

Extension of Drosophila melanogaster life span with a GPCR peptide inhibitor

G protein-coupled receptors (GPCRs) mediate signaling from extracellular ligands to intracellular signal transduction proteins. Methuselah (Mth) is a class B (secretin-like) GPCR, a family typified by their large, ligand-binding, N-terminal extracellular domains. Downregulation of mth increases the life span of Drosophila melanogaster; inhibitors of Mth signaling should therefore enhance longevity. We used mRNA display selection to identify high-affinity (K(d) = 15 to 30 nM) peptide ligands that bind to the N-terminal ectodomain of Mth. The selected peptides are potent antagonists of Mth signaling, and structural studies suggest that they perturb the interface between the Mth ecto- and transmembrane domains. Flies constitutively expressing a Mth antagonist peptide have a robust life span extension, which suggests that the peptides inhibit Mth signaling in vivo. Our work thus provides new life span-extending ligands for a metazoan and a general approach for the design of modulators of this important class of GPCRs.     

Antioxidative metabolism in down syndrome

Down syndrome is the most common cause of mental retardation, affecting 1 in 700–800 liveborn infants. Although numerous biochemical abnormalities accompanying the syndrome have not yet been completely clarified, the antioxidant defense system enzymes have shown to be altered due to increased gene dosage on chromosome 21 and overproduction of superoxide dismutase (SOD-1 or Cu/Zn SOD). The purpose of this study was to investigate the activities of SOD-1 and glutathione peroxidase (GSH-Px) enzymes and the levels of their cofactors zinc (Zn), copper (Cu) and selenium (Se) in plasma of 20 Down syndrome patients. In comparison with age and sex-matched controls (n=15), plasma GSH-Px, SOD, and Cu levels were significantly decreased in the patient group, but Zn and Se concentrations remained unchanged. This study was presented as a poster in 29th Annual Meeting of European Society of Human Genetics held in Genoa in May, 1997.     

Bioluminescence Imaging of Clavibacter michiganensis subsp. michiganensis Infection of Tomato Seeds and Plants

Clavibacter michiganensis subsp. michiganensis is a Gram-positive bacterium that causes wilting and cankers, leading to severe economic losses in commercial tomato production worldwide. The disease is transmitted from infected seeds to seedlings and mechanically from plant to plant during seedling production, grafting, pruning, and harvesting. Because of the lack of tools for genetic manipulation, very little is known regarding the mechanisms of seed and seedling infection and movement of C. michiganensis subsp. michiganensis in grafted plants, two focal points for application of bacterial canker control measures in tomato. To facilitate studies on the C. michiganensis subsp. michiganensis movement in tomato seed and grafted plants, we isolated a bioluminescent C. michiganensis subsp. michiganensis strain using the modified Tn1409 containing a promoterless lux reporter. A total of 19 bioluminescent C. michiganensis subsp. michiganensis mutants were obtained. All mutants tested induced a hypersensitive response in Mirabilis jalapa and caused wilting of tomato plants. Real-time colonization studies of germinating seeds using a virulent, stable, constitutively bioluminescent strain, BL-Cmm17, showed that C. michiganensis subsp. michiganensis aggregated on hypocotyls and cotyledons at an early stage of germination. In grafted seedlings in which either the rootstock or scion was exposed to BL-Cmm17 via a contaminated grafting knife, bacteria were translocated in both directions from the graft union at higher inoculum doses. These results emphasize the use of bioluminescent C. michiganensis subsp. michiganensis to help better elucidate the C. michiganensis subsp. michiganensis-tomato plant interactions. Further, we demonstrated the broader applicability of this tool by successful transformation of C. michiganensis subsp. nebraskensis with Tn1409::lux. Thus, our approach would be highly useful to understand the pathogenesis of diseases caused by other subspecies of the agriculturally important C. michiganensis.Clavibacter michiganensis subsp. michiganensis is a Gram-positive, aerobic bacterium that belongs to a group of plant-pathogenic actinomycetes (37). Infections by C. michiganensis subsp. michiganensis cause bacterial canker and wilt in tomato, which is considered one of the most destructive and economically significant diseases of this crop. Severe epidemics can cause up to 80% yield loss, mainly due to wilting and death of plants and lesions on fruit. Bacterial canker was first discovered in Michigan greenhouses in 1909 and has now been reported to occur in most tomato production areas around the world (11, 40).Plant wounds facilitate but are not required for infection by C. michiganensis subsp. michiganensis, which invades the xylem vessels and causes vascular disease with high titers (10⁹ bacteria/g of plant tissue) (2, 29), impairing water transport and leading to plant wilting, canker stem lesions, and death (17, 23). Alternatively, asymptomatic infections can be induced by C. michiganensis subsp. michiganensis during late stages of plant development, resulting in the production of contaminated seeds, a major source of outbreaks of C. michiganensis subsp. michiganensis infections in tomato production (13, 34). Traditional bacterial-disease management measures, such as applications of antibiotics and copper bactericides, have not been successful against this disease, and canker-resistant tomato cultivars are not available. As a result, C. michiganensis subsp. michiganensis has been included under international quarantine regulation (10, 11). Consequently, seed testing and maintaining pathogen-free seeds and transplants is currently the most appropriate approach to minimize the spread of disease (23). However, even a low C. michiganensis subsp. michiganensis transmission rate (0.01%) from seed to seedling can cause a disease epidemic under favorable conditions (5). Due to overcrowding of seedlings during transplant production, the pathogen can easily spread through splashing of irrigation water and leaf contact. Despite its apparent significance in C. michiganensis subsp. michiganensis epidemiology, the mechanism of seed-to-seedling transmission of C. michiganensis subsp. michiganensis is not well understood.Another critical point for disease spread is the grafting process, which is now a common practice for the majority of plants used in production greenhouses. Desirable tomato cultivars (scions) are grafted onto rootstocks that provide greater vigor, longevity, or, in some cases, disease resistance (26). Grafting requires cutting both rootstock and scion, providing a quick way for C. michiganensis subsp. michiganensis to spread from plant to plant. However, grafting is a relatively recent innovation in tomato production, and little is known about how grafting affects the dynamics of C. michiganensis subsp. michiganensis infection. Developing adequate control measures for C. michiganensis subsp. michiganensis is complicated by the complexity of genetic manipulation of Gram-positive bacteria, which impairs analysis and characterization of pathogenesis mechanisms (23). Consequently, there is a need to develop molecular techniques that would allow a better understanding of C. michiganensis subsp. michiganensis infections.One method of interest is using engineered bioluminescent bacteria to monitor plant-pathogen interactions in real time. By exploiting natural light-emitting reactions that are encoded by the luxCDABE genes, bioluminescent bacteria have been used to assess gene expression and to monitor the internalization and distribution of bacteria in hosts (3, 6, 7, 8, 9, 12, 15, 24, 31, 35, 36). In particular, bioluminescent phytopathogenic Xanthomonas campestris pathovars and Pseudomonas spp. have been used to track bacterial movement and distribution in host plants (7, 8, 15, 31, 36), as well as to assess host susceptibility quantitatively (15). Likewise, the lux genes have also been transferred to beneficial bacteria, such as Rhizobium leguminosarum and Pseudomonas spp. to visualize colonization patterns in rhizospheres (3, 9).The genes that carry the function of light emission are luxAB, which express luciferase enzymes that catalyze the bioluminescent reaction, while luxCDE encode the enzymes required for biosynthesis of a fatty aldehyde substrate necessary for the reaction (28, 39). Bioluminescence involves an intracellular oxidation of the reduced form of flavin mononucleotide and the fatty aldehyde by luciferase in the presence of molecular oxygen; therefore, bacterial bioluminescence also requires oxygen, a source of energy (38). Cells that express the lux operon spontaneously emit photons that can be captured by a sensitive charge-coupled-device (CCD) camera, enabling imaging and visualization of bacterial cells (22). Luciferase activity depends on the metabolic integrity of the cell, while the number of photons emitted correlates with the biomass of living bacteria (12, 31). Furthermore, since the half-life of luciferase binding to its substrate is several seconds (28), captured light events reflect processes in real time and are not artifacts of accumulated signals. Consequently, live imaging of bioluminescence provides a sensitive means of visualizing bacterial colonization and invasion of hosts and allows real-time representation and examination of pathogen-plant interactions (24, 36).Very little information is available about the mechanisms of C. michiganensis subsp. michiganensis pathogenesis and its colonization of seeds and subsequent transmission to seedlings. This is largely attributable to a lack of tools and difficulties in genetically manipulating this Gram-positive bacterium (30). However, recent development of an insertion sequence element IS1409 (Tn1409)-based efficient transposon mutagenesis system for C. michiganensis subsp. michiganensis has increased our knowledge of the pathogenesis of tomato canker (16, 25). To better understand the dynamics of seed-to-seedling transmission of C. michiganensis subsp. michiganensis, as well as movement of C. michiganensis subsp. michiganensis in grafted plants, we constructed a bioluminescent C. michiganensis subsp. michiganensis strain using the Tn1409 transposon mutagenesis system. Our results demonstrated the utility of using a bioluminescent C. michiganensis subsp. michiganensis strain as a novel approach to elucidate the interaction of plants with this economically important pathogen.     

Light activation of an innate olfactory avoidance response in Drosophila

How specific sensory stimuli evoke specific behaviors is a fundamental problem in neurobiology. In Drosophila, most odorants elicit attraction or avoidance depending on their concentration, as well as their identity [1]. Such odorants, moreover, typically activate combinations of glomeruli in the antennal lobe of the brain [2-4], complicating the dissection of the circuits translating odor recognition into behavior. Carbon dioxide (CO2), in contrast, elicits avoidance over a wide range of concentrations [5, 6] and activates only a single glomerulus, V [5]. The V glomerulus receives projections from olfactory receptor neurons (ORNs) that coexpress two GPCRs, Gr21a and Gr63a, that together comprise a CO2 receptor [7-9]. These CO2-sensitive ORNs, located in the ab1 sensilla of the antenna, are called ab1c neurons [10]. Genetic silencing of ab1c neurons indicates that they are necessary for CO2-avoidance behavior [5]. Whether activation of these neurons alone is sufficient to elicit this behavior, or whether CO2 avoidance requires additional inputs (e.g., from the respiratory system), remains unclear. Here, we show that artificial stimulation of ab1c neurons with light (normally attractive to flies) elicits the avoidance behavior typical of CO2. Thus, avoidance behavior appears hardwired into the olfactory circuitry that detects CO2 in Drosophila.     

In vitro antimicrobial activity of propolis samples from different geographical origins against certain oral pathogens

Propolis is an agent having antimicrobial properties, however, its composition can vary depending on the area where it is collected. In the present study, the antimicrobial activity of five propolis samples, collected from four different regions in Turkey and from Brazil, against nine anaerobic strains was evaluated. Ethanol extracts of propolis (EEP) were prepared from propolis samples and we determined minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of EEP on the growth of test microorganisms by using agar dilution method. All strains were susceptible and MIC values ranged from 4 to 512 microg/ml for propolis activity. Propolis from Kazan-Ankara showed most effective MIC values to the studied microorganisms. MBC values of Kazan-Ankara EEP samples were ranged from 8 to 512 microg/ml. Death was observed within 4 h of incubation for Peptostreptococcus anaerobius and micros and Lactobacillus acidophilus and Actinomyces naeslundii, while 8 h for Prevotella oralis and Prevotella melaninogenica and Porphyromonas gingivalis, 12 h for Fusobacterium nucleatum, 16 h for Veillonella parvula. It was shown that propolis samples were more effective against Gram positive anaerobic bacteria than Gram negative ones. The organic chemical compositions of EEPs were determined by high-resolution gas chromatography coupled to mass spectrometry (GC-MS). The main compounds of EEPs were flavonoids such as pinobanksin, quercetin, naringenin, galangine, chrysin and aromatic acids such as cafeic acid. Because of increased antimicrobial resistance, propolis may be kept in mind in the treatment of oral cavity diseases.     

Impact of tannic acid on blood pressure,oxidative stress and urinary parameters in L-NNA-induced hypertensive rats

Hypertension is a major health problem with increasing prevalence around the world. Tannic acid is water-soluble polyphenol that is present in tea, green tea, coffee, red wine, nuts, fruits and many plant foods. It has been reported to serve as an antioxidant or a pro-oxidant depending on the type of cells and its concentration. The purpose of our study was to evaluate the effect of tannic acid on systolic blood pressure, oxidative stress and some urinary parameters in the rat model of essential hypertension. Blood pressures of all rats were measured using the tail-cuff method. The nitric oxide synthase inhibitor N (omega)-nitro-L-arginine was administered orally at a dose of 0.5 g/l/day for 15 days to rats in order to create an animal model of hypertension. Tannic acid was intraperitoneally injected at a dose of 50 mg/kg for 15 days. Superoxide dismutase, catalase activity and the concentration of malondialdehyde (MDA) were determined in blood plasma and homogenates of heart, liver and kidney. In order to evaluate renal functions, urine pH, urine volume, urine creatine, uric acid, and urea nitrogen values were measured. Compared with the hypertension group, a decrease in MDA concentrations of heart tissue (p < 0.01), urea nitrogen values (p < 0.01) and urine volumes (p < 0.001) were established in hypertension + tannic acid group. There was also a decrease in blood pressure values (20th and 30th days) of this group, but there was no a statistical difference according to hypertension group. The findings of our research show the effect of tannic acid in lowering blood pressure in hypertensive rats.     

Tall cell variant of papillary carcinoma arising from a thyroglossal cyst: report of a case with diagnosis by fine needle aspiration cytology

BACKGROUND: Papillary carcinoma arising from a thyroglossal duct cyst (TDC) is the most frequent malignancy arising from this embryologic remnant of the thyroglossal duct. The preoperative fine needle aspiration cytology (FNAC) of such neoplasms has rarely been cited. Approximately 170 TDC cases have been reported in the literature worldwide, diagnosed solely on histopathology. CASE: A 63-year-old woman presented with an anterior midline neck mass of years' duration. A hypodense cyst was located at the level of the hyoid bone. FNAC of the midline neck mass showed bloody, mucoid material and numerous atypical, elongated cells. The aspirated material was reported as "papillary carcinoma possibly arising from the thyroglossal duct," and the diagnosis was confirmed by histopathologic investigation on resection material. CONCLUSION: Tall cell variant is a rare variant of papillary carcinoma and has a poor prognosis. The differential diagnosis includes Hürthle cell lesions, oncocytic papillary thyroid carcinoma and Warthin-like papillary carcinoma.