INTRACELLULAR LOCALIZATION OF KYNURENINE IN THE FATBODY OF DROSOPHILA

Light blue fluorescent globules accumulate in the cells of the anterior region of the fatbody of Drosophila larvae near the time of pupation. This fluorescent material appears in the Ore-R wild type strain as well as mutant strains in which the synthesis of both the red and brown eye pigments is affected. The vermilion mutant, which is characterized by the absence of the brown pigment component in the eye, was the only strain among those examined which did not develop the light blue fluorescent globules. Utilizing chromatographic techniques together with the information gained by examination of the mutant strains, the fluorescent material has been identified as kynurenine. Of particular interest is the manner of appearance of the fluorescent material in the vicinity of the nuclear membrane of the fat cells.     

Functional Significance of the Crystal Cells in the Larva of Drosophila melanogaster

Cytoplasmic crystalline inclusions are found in some larval haemocytes of Drosophila melanogaster. Blackening can be experimentally induced in these cells, and previously it was suggested that either the substrate or enzyme for the tyrosine-tyrosinase system leading to melanin production in Drosophila larvae is found in these inclusions in the crystal cells. The present report is an attempt to further localize the enzyme and substrate. Larvae have been fed on food containing α-C¹⁴-tyrosine and autoradiographs of the blood cells taken from these larvae subsequently prepared. The C¹⁴ activity in the crystal cells is restricted to the crystal inclusions in the cells and is significantly higher than that found in the other type of haemocytes, the plasmatocytes. When samples of the blood cells are incubated in DOPA solution, the extra-crystalline cytoplasm becomes blackened while the crystals themselves remain colorless. These observations are consistent with the hypothesis that the substrate is localized in the crystal inclusions whereas enzyme is found in the surrounding cytoplasm. An in vivo structural isolation would serve to separate enzyme and substrate rather than an inhibition by dehydrogenases as postulated by previous authors. In vitro examination with the phase microscope has shown that the crystal cells rupture easily and the crystals dissolve in the haemolymph. Therefore any treatment which tends to disrupt the structural integrity of the cell will allow the enzyme and substrate to come together. Humoral factors preceding metamorphosis might account for the in vivo release of the enzymatic reaction by initially altering the permeability of the cell.     

Design,in Silico Studies and Biological Evaluation of New Chiral Thiourea and 1,3-Thiazolidine-4,5-dione Derivatives

In this study, new chiral thiourea and 1,3-thiazolidine-4,5-dione derivatives were synthesized, it was aimed to evaluate the various biological activities and molecular docking of these compounds. Firstly, the new thioureas ( 1 – 16 ) were obtained by reacting 1-naphthylisothiocyanate with different chiral amines. Then, the chiral thioureas were cyclized with oxalyl chloride to obtain 1,3-thiazolidine-4,5-dione derivatives ( 17 – 32 ). All compounds were evaluated with several in vitro antioxidant and enzyme inhibition activities. Compound 30 was the most active compound against AChE, with a value of IC₅₀=8.09±0.58 μM. On the other hand, all compounds were tested in silico absorption, distribution, metabolism, and excretion (ADME) assays to better understand their bioavailability. These physicochemical properties, pharmacokinetics, and drug-likeness of all compounds were calculated using SwissADME. Furthermore, according to molecular docking analyses compound 30 exhibited significant binding affinities for all enzymes. Based on our overall observations, compound 30 could be recommended as a potential lead for the therapuetic of Alzheimer's.     

GENETIC CONTROL OF CYTODIFFERENTIATION

The cells of the anterior region of the larval fatbody of Drosophila melanogaster accumulate kynurenine at the end of the third larval instar, whereas the cells of the posterior region are involved in pteridine metabolism. Through a series of transplantation experiments it has been demonstrated that the anterior fat cells synthesize kynurenine. The mutant vermilion lacks kynurenine, and the anterior fat cells of this mutant strain lack the autofluorescence characteristic of kynurenine. When the non-allelic suppressor gene is combined with vermilion, the synthesis of kynurenine is restored in the anterior fat cells, and some of the cells of the posterior region contain kynurenine as well. A similar extension in the number of cells containing kynurenine can be induced in the normal Ore-R strain by feeding the precursor tryptophan. It has been concluded that the absence of a physiological process in a differentiated cell does not necessarily represent a loss of the genetic potential for that process. The normal allele at the suppressor locus inhibits the occurrence of kynurenine in the posterior fat cells, whereas the mutant allele su²-s allows the expression of this potential. An inducer such as tryptophan can overcome this inhibition in the normal strain, and as a result the cells which are normally differentiated as "isoxanthopterin cells" may produce kynurenine as well.     

Leptopilina heterotoma and L. boulardi: strategies to avoid cellular defense responses of Drosophila melanogaster

Eggs of three strains of the cynipid parasitoid Leptopilina heterotoma and a Tunisian strain (G317) of L. boulardi are not encapsulated by hemocytes of Drosophila melanogaster hosts, but the eggs of a Congolese strain (L104) of L. boulardi are encapsulated. To determine the reason for the difference in host response against the parasitoid eggs, lamellocytes (hemocytes that encapsulate foreign objects and form capsules around endogenous tissues in melanotic tumor mutants) were examined in host larvae parasitized by the five Leptopilina strains. Parasitization by the three L. heterotoma strains affected the morphology of host lamellocytes and suppressed endogenous melanotic capsule formation in melanotic tumor hosts. L104 did not alter the morphology of host lamellocytes nor block tumor formation in melanotic tumor mutant hosts. The morphology of some lamellocytes was affected by G317 parasitization but host lamellocytes were still capable of forming melanotic tumors and encapsulating dead supernumerary parasitoid larvae. Therefore, the eggs of strains affecting lamellocyte morphology are protected from encapsulation by the host's blood cells. L. heterotoma eggs float freely in the host hemocoel but L. boulardi eggs are attached to host tissue surfaces. Lamellocytes cannot infiltrate the attachment site so the capsule around the L104 egg remains incomplete. The wasp larva uses this gap in the capsule as an escape hatch for emergence.     

Calcium hypochlorite on mouse embryonic fibroblast cells (NIH3T3) in vitro cytotoxicity and genotoxicity: MTT and comet assay

Molecular Biology Reports - Antimicrobial irrigation solutions are widely used under clinical settings. Their effect on dental tissue is a subject of recent research, which aims for a safer...