Nazife Yigit

Antimicrobial activity of endemic Crataegus tanacetifolia (Lam.) Pers and observation of the inhibition effect on bacterial cells.

Up to now an increasing number of antibiotic‐resistant bacteria have been reported and thus new natural therapeutic agents are needed in order to eradicate these pathogens. Through the discovery of plants such as Crataegus tanacetifolia (Lam.) Pers that have antimicrobial activity, it will be possible to discover new natural drugs serving as chemotherapeutic agents for the treatment of nosocomial pathogens and take these antibiotic‐resistant bacteria under control. The objective of the present study was to determine antimicrobial activity and the activity mechanism of C. tanacetifolia plant extract. The leaves of C. tanacetifolia, which is an endemic plant, were extracted using methanol and tested against 10 bacterial and 4 yeast strains by using a drop method. It was observed that the plant extract had antibacterial effects on Bacillus subtilis, Shigella, Staphylococcus aureus, and Listeria monocytogenes among the microorganisms that were tested. Minimum inhibitory concentration (MIC) results obtained at the end of an incubation of 24 h were found to be ≥6.16 mg ml−1 for B. subtilis, <394 mg ml−1 for Shigella, and ≥3.08 mg ml−1 for L. monocytogenes and S. aureus and minimum bactericidal concentration (MBC) were found as ≥24.63 mg ml−1 for B. subtilis, ≥394 mg ml−1 for Shigella, ≥6.16 mg ml−1 for L. monocytogenes, and ≥98.5 mg ml−1 for S. aureus. According to the MBC results, it was found that the plant extract had bactericidal effects and in order to explain the activity mechanism and cell deformation of bacterial strains treated with plant extract, the scanning electron microscopy (SEM) was used. The results of SEM showed that the treated cells appeared shrunken and there was degradation of the cell walls. This study, in which the antibacterial effect of C. tanacetifolia was demonstrated, will be a base for further investigations on advanced purification and effect mechanism of action of its active compounds. Copyright

Antibacterial activity of venom from funnel web spider Agelena labyrinthica (Araneae: Agelenidae)

Since the number of microorganisms that are resistant to antibiotics has been increasing steadily, the need for combating these pathogens requires new pharmaceutical agents. To produce these substances, new models have been developed in recent decades. In our study, the venom of Agelena labyrinthica (Clerck, 1757) (Araneae: Agelenidae) was tested against ten bacterial strains, specifically, testing 1/100, 1/10 and 1/1 fractions of diluted venom against these bacteria. While the 1/100 dilution was successful in only one of ten bacterial strains, the 1/10 and the 1/1 were effective on six of ten bacterial strains. The most effective results, among these three different concentrations, were observed on Bacillus subtilis. The other five strains that were also sensitive to the dilutions showed similar inhibition zones. Morphological alterations on bacterial cells and comparison with normal cells were accomplished by scanning electron microscopy (SEM). The venom-treated cells, due to their loss of cytoplasm, shrank and presented cell wall depression.

The venom gland of the scorpion species Euscorpius mingrelicus (Scorpiones: Euscorpiidae): morphological and ultrastructural characterization

The histology and ultrastructure of venom glands in the scorpion Euscorpius mingrelicus (Kessler, 1874) are described and illustrated in the current study for the first time by employing light microscopy and transmission electron microscopy (TEM). The venom apparatus is composed of a pair of venom glands and a stinger, both situated in the last segment of the metasoma. The venom glands are completely separate but similar. The two glands are segregated within the telson by striated muscle bundles, and their outer surfaces are surrounded by a cuticle. An internal layer constitutes the secretory epithelium. This epithelium is made up of simple columnar cells. The nucleus and organelles involved in cellular synthetic activity are situated basally. In the apical portion, near the gland lumen, there are many secretory granules of different sizes, shapes and electron densities.

Fine structural analysis of the stinger in venom apparatus of the scorpion Euscorpius mingrelicus (Scorpiones: Euscorpiidae)

In this study, the morphology, histology and fine structure of the stinger, a part of the venom apparatus of Euscorpius mingrelicus (Kessler, 1874) (Scorpiones: Euscorpiidae) were studied by light microscopy and transmission electron microscopy (TEM). The stinger, located at the end section of the telson, is sickle-shaped. The venom is ejected through a pair of venom pores on its subterminal portion. Both venom ducts extend along the stinger without contact with each other since they are separated by connective tissue cells. The stinger cuticle is composed of two layers. Additionally, there are many pore canals and some hemolymph vessels in the cuticle. This work constitutes the first histological and fine structure study on Euscorpius mingrelicus stinger.