Ingrowth by photoreceptor axons induces transcription of a retrotransposon in the developing Drosophila brain

The development of the lamina, the first optic ganglion of the fly visual system, depends on inductive cues from the innervating photoreceptor axons. lacZ expression from a P-element insertion, A72, occurs in the anlage of the lamina coincident with axon ingrowth from the eye imaginal disc. In eyeless mutants lacking photoreceptor axons, lacZ expression did not occur. The P-element was found to have inserted within the 3′ long terminal repeat (LTR) of a ‘17.6′ type retrotransposon. The expression pattern of 17.6 transcripts in the brain in wild-type and eyeless mutants paralleled the expression of the lacZ reporter. Analysis of 17.6 cis-regulatory sequences indicates that the lamina-specific expression is due to the combined action of an enhancer element in the LTR and a repressor element within the internal body of the retrotransposon. The regulation of the 17.6 retrotransposon provides a model for the study of innervation-dependent gene expression in postsynaptic cells during neurogenesis

The Predicted Binding Site and Dynamics of Peptide Inhibitors to the Methuselah GPCR from Drosophila melanogaster

Peptide inhibitors of Methuselah (Mth), a G protein-coupled receptor (GPCR), were reported that can extend the life span of Drosophila melanogaster. Mth is a class B GPCR, which is characterized by a large, N-terminal ectodomain that is often involved with ligand recognition. The crystal structure of the Mth ectodomain, which binds to the peptide inhibitors with high affinity, was previously determined. Here we report the predicted structures for RWR motif peptides in complex with the Mth ectodomain. We studied representatives of both Pro-class and Arg-class RWR motif peptides and identified ectodomain residues Asp139, Phe130, Asp127, and Asp78 as critical in ligand binding. To validate these structures, we predicted the effects of various ligand mutations on the structure and binding to Mth. The binding of five mutant peptides to Mth was characterized experimentally by surface plasmon resonance, revealing measured affinities that are consistent with predictions. The electron density map calculated from our MD structure compares well with the experimental map of a previously determined peptide/Mth crystal structure and could be useful in refining the current low-resolution data. The elucidation of the ligand binding site may be useful in analyzing likely binding sites in other class B GPCRs

Breeding properties of Tinca tinca (L., 1758) living in Kapulukaya Reservoir (Kirikkale, Turkey)

This study involves the investigation of Tinca tinca (L., 1758) living in Kapulukaya Reservoir in Turkey. It was observed that the fish reach sexual maturity at the age of III and the breeding period starts in May and ends in July. The mean monthly gonadosomatic indices varied from 1.38 ±0.06 (in October) to 8.01±1.03 (in May). According to monthly variations of the GSI, spawning of the tench takes place between May (8.01 ± 1.03) and June (5.50 ± 0.57). The average egg number per fish was estimated to be 23403 ± 17047 . The eggs diameters varied from 0.50 mm to 1.33 mm (mean 0.86 mm). The relations between the fecundity (F) and body length (L) and body weight (W) were found as F = 0.037799 × L 1.0212 (r = 0.70) and F = 0. 00000175 × W 2.8696 (r = 0.62)

Short communication: Growth properties of tench (Tinca tinca L., 1758) living in Hirfanlı Reservoir (Kırşehir, Turkey)

Tinca tinca is originally from the Near East and West-Siberia and nowadays is spread all over the world. Previous reports showed that they abundantly present in the rivers flowing to the Black Sea and various lakes as well as in rivers in Central Anatolia. It has no economical importance due to its slow growth rate and tasteless meat. There are many publications on the growth and the bio-ecology and feeding of T. tinca. This study was carried out to investigate the growth properties, such as weight, length and condition factor, in T. tinca inhabit in Hirfanlı Reservoir built in 1959 on Kızılırmak River with the altitude of 856m and volume of 7.63 x10^9m^3. The study was carried out from August 1996 to July 1997 on 241 T. tinca species

Subcellular localization of transcripts in Drosophila photoreceptor neurons: chaoptic mutants have an aberrant distribution

Photoreceptor neurons in the Drosophila retina are long (100 mu) and narrow, providing a system for the study of the intracellular distribution of transcripts and proteins. The chaoptic gene is expressed exclusively in photoreceptor neurons, and mutations of the gene result in reduced developmental competence of cells to generate normal rhabdomeric membranes. The mutant protein exhibited altered distribution both in developing and adult photoreceptor neurons. Furthermore, the transcript distribution in mutants was altered, decreasing with distance from the nucleus, instead of the normal uniform distribution throughout the cell soma. The deficit of transcript concentration correlated with the severity of developmental defect in rhabdomere formation along the cell. In contrast, the distribution of the opsin transcript was not affected by the chaoptic mutation. To observe RNA localization at the ultrastructural level, a high-resolution, electron microscopic in situ hybridization protocol was developed. The results indicate that the normal chaoptic transcript is present on the rough endoplasmic reticulum, which may be a vehicle for specific transcript distribution

Electron Tomographic Studies of Mitochondrial Crista Topology: “Swirl” Mitochondria of Drosophila Flight Muscle

Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Florida, USA, August 5 – August 9, 2007

Generation of cDNA expression libraries enriched for in-frame sequences

Bacterial cDNA expression libraries are made to reproduce protein sequences present in the mRNA source tissue. However, there is no control over which frame of the cDNA is translated, because translation of the cDNA must be initiated on vector sequence. In a library of nondirectionally cloned cDNAs, only some 8% of the protein sequences produced are expected to be correct. Directional cloning can increase this by a factor of two, but it does not solve the frame problem. We have therefore developed and tested a library construction methodology using a novel vector, pKE-1, with which translation in the correct reading frame confers kanamycin resistance on the host. Following kanamycin selection, the cDNA libraries contained 60–80% open, in-frame clones. These, compared with unselected libraries, showed a 10-fold increase in the number of matches between the cDNA-encoded proteins made by the bacteria and database protein sequences. cDNA sequencing programs will benefit from the enrichment for correct coding sequences, and screening methods requiring protein expression will benefit from the enrichment for authentic translation products

Serum Endothelin-1 and Transforming Growth Factor-β Levels in the Newborns With Respiratory Distress

The purpose of this present study was to evaluate the serum levels of ET-1 and TGF-β in the newborns with respiratory distress. In this study, newborns with respiratory distress hospitalized into the Newborn Intensive Care Unit were included. The highest values of ET-1 and TGF-β were obtained from newborns with diagnosis as meconium aspiration syndrome (5.70 ± 5.87 pg/mL and 3.75 ± 1.94 pg/mL, resp) in the sample obtained in the first six hours after birth, and these are statistically different from control group (P < .05). Also, same results were obtained for newborns with respiratory distress syndrome (3.37 ± 1.59 pg/mL and 2.05 ± 0.98 pg/mL, resp). After oxygen treatment, ET-1 values obtained in the first six hours of life were decreased regularly in the following days (P < .05). In the differentiating diagnosis of the respiratory distress of newborns, the investigation of ET-1 and TGF-β levels is meaningful. The ET-1 levels investigated in the first six hours is more useful in determining the prognosis, and repeating ET-1 levels in the following days is more meaningful to determine clinical response