Dissecting the Function of Ack Family Kinases in Drosophila Through Understanding Their Interactions with Dock and CDC42

Deregulation of Ack (Activated Cdc42-associated Kinase) family of non-receptor tyrosine kinases in mammals correlates with poor prognosis in cancers and has been implicated in promoting metastasis. In Drosophila, Ack family is constituted of two kinases: Ack and PR2. To further understand the in vivo function of this family we have conducted two projects: First we, we characterized the developmental defects of a null mutation in Drosophila Ack, which bears a high degree of sequence similarity to mammalian ACK1 but lacks a CRIB domain. We show that Ack, while not essential for viability, is critical for sperm formation. This function depends on Ack tyrosine kinase activity and is required cell autonomously in differentiating male germ cells at or after the spermatocyte stage. Ack associates predominantly with endocytic clathrin sites in spermatocytes, but disruption of Ack function has no apparent effect on clathrin localization and receptor-mediated internalization of Boss (Bride of sevenless) protein in eye discs. Instead, Ack is required for the subcellular distribution of Dock (dreadlocks), the Drosophila homolog of the SH2- and SH3-containing adapter protein Nck. Moreover, Dock forms a complex with Ack, and the localization of Dock in male germ cells depends on its SH2 domain. Together, our results suggest that Ack-dependent tyrosine phosphorylation recruits Dock to promote sperm differentiation. Second, despite the fact that ACK1 has been originally identified by its ability to bind to activated Cdc42, the physiological relevance of this binding has not been described. To test the significance of this interaction, we have established an over-expression system of various Cdc42 constructs in Drosophila germ cells. Similar to Drosophila embryos, expression of constitutively active Cdc42 (Cdc42G12V) in Drosophila spermatocytes results in cytokinesis defects, suggesting the step(s) affected by excessive Cdc42 activity is both meiotic and mitotic. Cdc42G12V is recruited to the site of cytokinesis ring constriction in germ cells where an increase in the level of tyrosine phosphorylation is also observed. This implies that a tyrosine kinase/substrate responds to Cdc42 activation. Indeed, loss-of-function mutations in PR2 but not Ack suppresses Cdc42G12V-dependent cytokinesis defect, suggesting that PR2 acts downstream of Cdc42. Moreover, PR2 is co-IPed with activated Cdc42 but not wild type Cdc42. Finally we show that Cdc42 G12V alters the subcellular localization of PR2 recruiting it to the site of cellular division

Some New Concepts of Shape Memory Effect of Polymers

In this study some new concepts regarding certain aspects related to shape memory polymers are presented. A blend of polylactic acid (PLA) (80%) and polybutylene succinate (PBS) (20%) was prepared first by extrusion, then by injection molding to obtain the samples. Tensile, stress-relaxation and recovery tests were performed on these samples at 70 °C. The results indicated that the blend can only regain 24% of its initial shape. It was shown that, this partial shape memory effect could be improved by successive cycles of shape memory tests. After a fourth cycle, the blend is able to regain 82% of its shape. These original results indicated that a polymer without (or with partial) shape memory effect may be transformed into a shape memory polymer without any chemical modification. In this work, we have also shown the relationship between shape memory and property memory effect. Mono and multi-frequency DMA (dynamic mechanical analyzer) tests on virgin and 100% recovered samples of polyurethane (PU) revealed that the polymer at the end of the shape memory tests regains 100% of its initial form without regaining some of its physical properties like glass transition temperature, tensile modulus, heat expansion coefficient and free volume fraction. Shape memory (with and without stress-relaxation) tests were performed on the samples in order to show the role of residual stresses during recovery tests. On the basis of the results we have tried to show the origin of the driving force responsible for shape memory effect

Dipeptide repeat proteins inhibit homology-directed DNA double strand break repair in C9ORF72 ALS/FTD

BACKGROUND: The C9ORF72 hexanucleotide repeat expansion is the most common known genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two fatal age-related neurodegenerative diseases. The C9ORF72 expansion encodes five dipeptide repeat proteins (DPRs) that are produced through a non-canonical translation mechanism. Among the DPRs, proline-arginine (PR), glycine-arginine (GR), and glycine-alanine (GA) are the most neurotoxic and increase the frequency of DNA double strand breaks (DSBs). While the accumulation of these genotoxic lesions is increasingly recognized as a feature of disease, the mechanism(s) of DPR-mediated DNA damage are ill-defined and the effect of DPRs on the efficiency of each DNA DSB repair pathways has not been previously evaluated. METHODS AND RESULTS: Using DNA DSB repair assays, we evaluated the efficiency of specific repair pathways, and found that PR, GR and GA decrease the efficiency of non-homologous end joining (NHEJ), single strand annealing (SSA), and microhomology-mediated end joining (MMEJ), but not homologous recombination (HR). We found that PR inhibits DNA DSB repair, in part, by binding to the nucleolar protein nucleophosmin (NPM1). Depletion of NPM1 inhibited NHEJ and SSA, suggesting that NPM1 loss-of-function in PR expressing cells leads to impediments of both non-homologous and homology-directed DNA DSB repair pathways. By deleting NPM1 sub-cellular localization signals, we found that PR binds NPM1 regardless of the cellular compartment to which NPM1 was directed. Deletion of the NPM1 acidic loop motif, known to engage other arginine-rich proteins, abrogated PR and NPM1 binding. Using confocal and super-resolution immunofluorescence microscopy, we found that levels of RAD52, a component of the SSA repair machinery, were significantly increased iPSC neurons relative to isogenic controls in which the C9ORF72 expansion had been deleted using CRISPR/Cas9 genome editing. Western analysis of post-mortem brain tissues confirmed that RAD52 immunoreactivity is significantly increased in C9ALS/FTD samples as compared to controls. CONCLUSIONS: Collectively, we characterized the inhibitory effects of DPRs on key DNA DSB repair pathways, identified NPM1 as a facilitator of DNA repair that is inhibited by PR, and revealed deficits in homology-directed DNA DSB repair pathways as a novel feature of C9ORF72-related disease

ANTIFUNGAL ACTIVITY OF CHITOSAN AGAINST Rhizopus stolonifer

These days instead of chemical pesticides, various natural alternatives have been used for the management of post-harvest diseases. This research was carried out to evaluate the antifungal potential of different chitosan concentrations viz., 5, 10, and 15 mg/µl against Rhizopus stolonifer by the agar dilution and well diffusion methods. The evaluation was carried out after seven days of incubation by measuring the inhibition of R. stolonifer mycelial growth. Results of the study revealed that the chitosan had a significant inhibitory effect on mycelial growth and maximum mycelial growth inhibition was reported at the 10 and 15 mg/µl concentrations and these two treatments are not significantly different. Based on these results, the best concentration (15 mg/µl) was further evaluated by the well diffusion technique. The average inhibition zones formed by the higher concentration was 25mm. Results of the study suggested that chitosan can be used for the management of post-harvesting diseases of tomatoes

A study on the characteristics of Algerian Hassi-Messaoud asphaltenes:Algerian Hassi-Messaoud asphaltenes: solubility and precipitation

This study focuses on detailed characterizations of asphaltene fractions extracted from the Algerian Hassi-Messaoud oil field. It was found that the extracted asphaltenes are not completely soluble in toluene, instead two fractions of asphaltenes were obtained upon solubilizing the heptane-precipitated neat asphaltenes in toluene. Extensive characterizations of the toluene-soluble and insoluble fractions were carried out using elemental analysis, Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (ssNMR). It was suggested that the high oxygen content and uneven compositional structures are the main contributors to asphaltene instability. The toluene-insoluble fractions were found to have higher polarity and aromaticity as well as more oxygen content than the neat asphaltenes and toluene-soluble fractions

The spectrum of MEFV gene mutations and genotype-phenotype correlation in Egyptian patients with familial Mediterranean fever

Background: Familial Mediterranean fever (FMF) is an autosomal recessive disease mainly affecting subjects of the Mediterranean origin. It is an auto-inflammatory periodic disorder that is caused by mutations in the Mediterranean fever gene (MEFV) located on chromosome 16.Methods: The current study was designed to assess the prevalence and frequency of different MEFV gene mutations among 104 FMF clinically diagnosed Egyptian patients and to evaluate the change extent in the values of some biochemical markers (ESR, CRP, Fibrinogen-C, SAA and IL1) in different participants with different FMF severity scores.Results: According to allele status 28 patients (27%) were homozygous mutation carriers, 38 (36.5%) were with compound heterozygous mutations and 38 (36.5%) were identified as heterozygous for one of the studied mutations. Of the studied mutations, M694I, E148Q, V726A, M680I, and M694V accounted for 28.1%, 26.8%, 16.9%, and 11.3% of mutations respectively. The R761H and P369S mutations were rarely encountered mutations (1.4%). The clinical features with M694I were associated with more severe clinical course. There is a drastic elevation in the levels of estimated parameters as their levels were increased as long as the severity of the disease increased.Conclusions: The diagnosis of FMF cannot be performed on the basis of genetic testing or clinical criteria alone. So, we recommended the combination between clinical and molecular profiling for FMF diagnosis and scoring

First trimester spontaneous rupture of an unscarred uterus in a multiparous woman: a case report

The rupture of an unscarred uterine is a rare life-threatening event that usually occurs late in pregnancy or during labor. Spontaneous uterine rupture, as in our case, is extremely uncommon and rarely diagnosed before laparotomy. Herein, we present a case of spontaneous uterine rupture in a 32 year old multiparous woman with no previous uterine surgery. The patient presented with acute abdomen at 11 weeks of gestation. Preoperative diagnosis based on clinical and ultra-sonographic findings was ruptured ectopic pregnancy. However, emergency laparotomy showed uterine rupture with extrusion of a dead fetus within intact amniotic sac in the abdomen. The defect was repaired in layers and the patient was discharged in a good condition after five days of hospital stay. Multiparity is a risk factor for spontaneous uterine rupture even in the first trimester. It should be kept in mind in any pregnant multiparous woman presenting with acute abdomen and shock. The absence of vaginal spotting and lack of history of uterine surgery give a false sense of security