Co-ordination between membrane oriC sequestration factors and a chromosome partitioning protein, TolC (MukA)

oriC DNA in the hemimethylated (but not in the fully methylated) state reacts with an Escherichia coli K-12 outer membrane preparation. This reaction is drastically reduced when the membrane preparation of a seqA null mutant is used. An in vitro reconstitution of the activity was undertaken by adding a partially purified SeqA protein to a seqA mutant membrane without success. A possible reason for this failure might be a profound modification of the outer membrane of the seqA mutant (as revealed by the fact that membrane from the mutant sediments more slowly than that from the wild type during ultracentrifugation). There is also a reduction in the content of OmpF protein. Moreover, one of the minor outer membrane proteins involved in partitioning of newly synthesized chromosomes, the TolC (MukA) protein, was also found to be downregulated in the seqA mutant. This is also true of the hobH mutant grown in a high-osmolarity medium. Mutants of both seqA and hobH stop dividing after hyperosmotic shock, forming filaments (as observed in dam mutants).     

Liraglutide ameliorated peripheral neuropathy in diabetic rats: Involvement of oxidative stress,inflammation and extracellular matrix remodeling

Diabetic peripheral neuropathy is one of the most common microvascular complications that occurs with both type 1 and type 2 diabetes mellitus. It has a significant negative impact on patients’ quality of life; as it starts with loss of limbs’ sensation and may lead to lower limb amputation. This study aimed at investigating the effect of liraglutide on peripheral neuropathy in diabetic rats. Experimental diabetes was induced by single intraperitoneal injections of nicotinamide (50 mg/kg) and streptozotocin (52.5 mg/kg). Rats were allocated into five groups. Two groups were given saline or liraglutide (0.8 mg/kg, s.c.). Three diabetic groups were either untreated or treated with liraglutide (0.8 mg/kg, s.c.) or pregabalin (10 mg/kg, i.p.). After 2 weeks of treatment, behavioral, biochemical, histopathological, and immunohistochemical investigations were performed. Treatment with liraglutide‐restored animals’ body weight, normalized blood glucose, decreased glycated hemoglobin, and increased insulin levels. In parallel, it normalized motor coordination and the latency withdrawal time of both tail flick and hind paw cold allodynia tests and reversed histopathological alterations. Treatment with liraglutide also normalized malondialdehyde, matrix metalloproteinase‐2 and ‐9 contents in sciatic nerve. Likewise, it decreased sciatic nerve nitric oxide and interleukin‐6 contents, DNA fragmentation and expression of cyclooxygenase‐2. Meanwhile, it increased superoxide dismutase and interleukin‐10 contents in sciatic nerve. These findings indicate the neuroprotective effect of liraglutide against diabetic peripheral neuropathy probably via modulating oxidative stress, inflammation, and extracellular matrix remodeling.

     

Cigarette Smoking and Hyperglycemia Increase Renal Response to Low Levels of Cadmium in Welders: Cystatin C as a Sensitive Marker

The present study was undertaken to investigate the utility of cystatin C (CysC) as an early biomarker of cadmium (Cd)-induced renal injury. The study was carried out on 50 adult male individuals divided into five groups of 10 individuals as follows: control, welders, smoker welders, diabetic welders, and smoker diabetic welders. The results indicated that plasma levels of CysC, creatinine, urea, and uric acid were significantly higher in welders compared to control individuals. In addition, the levels of whole blood Cd, lipid peroxidation, and protein oxidation products as well as erythrocyte osmotic fragility were significantly higher in welders compared to control individuals. In contrast, the levels of plasma albumin and whole blood glutathione were significantly decreased in welders compared to control individuals. The alterations of the measured parameters were enhanced in the presence of smoking and hyperglycemia besides exposure to welding fumes. These results suggest that CysC can be used as a sensitive biomarker of the early stages of Cd-induced renal injury.     

Proteomic Analysis of Intact Flagella of Procyclic Trypanosoma brucei Cells Identifies Novel Flagellar Proteins with Unique Sub-localization and Dynamics

Cilia and flagella are complex organelles made of hundreds of proteins of highly variable structures and functions. Here we report the purification of intact flagella from the procyclic stage of Trypanosoma brucei using mechanical shearing. Structural preservation was confirmed by transmission electron microscopy that showed that flagella still contained typical elements such as the membrane, the axoneme, the paraflagellar rod, and the intraflagellar transport particles. It also revealed that flagella severed below the basal body, and were not contaminated by other cytoskeletal structures such as the flagellar pocket collar or the adhesion zone filament. Mass spectrometry analysis identified a total of 751 proteins with high confidence, including 88% of known flagellar components. Comparison with the cell debris fraction revealed that more than half of the flagellum markers were enriched in flagella and this enrichment criterion was taken into account to identify 212 proteins not previously reported to be associated to flagella. Nine of these were experimentally validated including a 14-3-3 protein not yet reported to be associated to flagella and eight novel proteins termed FLAM (FLAgellar Member). Remarkably, they localized to five different subdomains of the flagellum. For example, FLAM6 is restricted to the proximal half of the axoneme, no matter its length. In contrast, FLAM8 is progressively accumulating at the distal tip of growing flagella and half of it still needs to be added after cell division. A combination of RNA interference and Fluorescence Recovery After Photobleaching approaches demonstrated very different dynamics from one protein to the other, but also according to the stage of construction and the age of the flagellum. Structural proteins are added to the distal tip of the elongating flagellum and exhibit slow turnover whereas membrane proteins such as the arginine kinase show rapid turnover without a detectible polarity.Cilia and flagella are prominent organelles of many eukaryotic cells. The names “cilia” and “flagella” are often related to historical reasons but they correspond to the same entity: a cylindrical organelle surrounded by a membrane and composed of an axoneme, a set of nine doublet microtubules originating from the basal body. Motile cilia usually contain a central pair of single microtubules and various substructures involved in the generation or the control of flagellar or ciliary beating, such as dynein arms, radial spokes, or central pair projections. This structural organization is remarkably well conserved across evolution, being encountered from protists to mammals (1). The conservation is also found at the molecular level as observed by comparative genomics between species with or without cilia and flagella (2, 3). Nevertheless, proteomic analysis revealed that in addition to the common core, many components unique to each group of eukaryotes are also present (4–8).The cilium represents a separate compartment from the cell body and does not contain any ribosomes or vesicles of any kind. The base of cilia and flagella contains projections that link each microtubule triplet of the basal body to the flagellum membrane (9). This region has been proposed to act as a barrier restricting entry of cytoplasmic proteins and ensuring retention of flagellum matrix elements (10). The transition zone is found in-between this area and the axoneme and contains several complexes of proteins (many of whom are mutated in the case of ciliopathies, genetic diseases affecting cilia function and/or formation) that contribute to the definition of the ciliary compartment (11, 12). Recent data showed that dextrans of low molecular weight are free to diffuse in the ciliary compartment as well as in the nucleus, whereas molecules of higher size (30 kDa or above) could not access these organelles. This led to the finding that a structure equivalent to the nucleopore complex is localized at the basal body area and could control access to the ciliary compartment (13). Finally, a septin barrier appears to be present close to the basis of the cilium and could control the trafficking of specific ciliary membrane proteins (14). The existence of a specific compartment comprising a large number of skeletal, matrix, and membrane proteins raises the issue of its internal organization. Key questions include the distribution of proteins, the mechanisms involved in specific distribution and the turnover during the life of the organelle.We selected to address these basic phenomena in the protist Trypanosoma brucei, well known as the etiological agent of sleeping sickness in Africa, but that is also an amenable model for cilia studies (15). It possesses a single flagellum that contains a typical 9 + 2 axoneme emerging from a depression of the cell surface called the flagellar pocket. This structure can be related to the ciliary pocket found at the base of different types of cilia in mammalian cells (16, 17). The axoneme is flanked by a lattice-like structure called the paraflagellar rod (PFR)¹ that is present as soon as the flagellum emerges from the pocket and runs to its distal end (18). The PFR contains at least 30 different proteins (19) and has been proposed to contribute to cell motility because its ablation results in cell paralysis in T. brucei (20) and in the related parasite Leishmania mexicana (21). The flagellum is attached to the cell body for most of its length, with the PFR lying close to the cell body side where a specific cytoskeletal structure termed the flagellum attachment zone (FAZ) is found (22). It is made of a unique filament composed of trypanosome-specific proteins (23, 24) and of four specialized microtubules flanked by the smooth endoplasmic reticulum (25). The flagellum plays key cellular functions as it drives cell motility (4, 26, 27), controls cell morphogenesis (28) and is responsible for parasite attachment during invasion of the salivary glands in the tsetse fly (29). Moreover, it could perform sensory functions and contribute to detection of the environment during the parasite life cycle (30). Recent data revealed the essential role of flagellum beating during fly invasion (31) but surprisingly reduction of forward motility did not affect infectivity in a mouse model (32).Purification of intact flagella from trypanosomes is a challenging task because of the adhesion to the cell body. Detergent and high-salt treatment have been used to efficiently purify the skeletal fraction of the flagellum that contains the axoneme, the PFR, and the basal body but that also includes the kinetoplast (mitochondrial genome), the FAZ, and the flagellar pocket collar (4, 33, 34). However, membrane and matrix components are totally lost during this procedure. For example, none of the intraflagellar transport (IFT) proteins that normally traffic in the flagellum matrix along peripheral microtubules (35) could be detected in samples purified by this procedure (4). We therefore decided to purify intact flagella by using a mutant strain called FLA1^RNAi where expression of an mRNA encoding a protein essential for flagellum attachment to the cell body (36) can be conditionally knocked-down by RNAi (37). FLA1^RNAi cells exhibit detached flagella from the main cell body, with the exception of the anchoring point at the basal body (37). By mechanical shearing, we found out that flagella could be severed from the cell body while preserving their membrane and their matrix elements. After purification, flagellar fractions were exhaustively characterized at the level of light and electron microscopy and their content was determined by mass spectrometry that confirmed the presence of the majority of known flagellar markers and revealed novel flagellar components. Three previously characterized proteins (the arginine kinase and two 14-3-3 proteins) and 10 hypothetical proteins were investigated in detail. Out of these 13 candidate proteins, 10 turned out to be associated to the flagellum whereas the others could not be detected experimentally. The novel ones were termed FLAM, for Flagellum Members. Remarkably, these proteins showed very specific location patterns within the flagellum including the membrane, the distal tip of the axoneme or the first proximal half of the axoneme, and displayed unexpected variations in their turnover rate. Overall, we revealed the existence of multiple subdomains within the flagellum with very specific dynamics, further demonstrating the highly sophisticated organization of the organelle.     

AIF promotes chromatinolysis and caspase‐independent programmed necrosis by interacting with histone H2AX

Programmed necrosis induced by DNA alkylating agents, such as MNNG, is a caspase‐independent mode of cell death mediated by apoptosis‐inducing factor (AIF). After poly(ADP‐ribose) polymerase 1, calpain, and Bax activation, AIF moves from the mitochondria to the nucleus where it induces chromatinolysis and cell death. The mechanisms underlying the nuclear action of AIF are, however, largely unknown. We show here that, through its C‐terminal proline‐rich binding domain (PBD, residues 543–559), AIF associates in the nucleus with histone H2AX. This interaction regulates chromatinolysis and programmed necrosis by generating an active DNA‐degrading complex with cyclophilin A (CypA). Deletion or directed mutagenesis in the AIF C‐terminal PBD abolishes AIF/H2AX interaction and AIF‐mediated chromatinolysis. H2AX genetic ablation or CypA downregulation confers resistance to programmed necrosis. AIF fails to induce chromatinolysis in H2AX or CypA‐deficient nuclei. We also establish that H2AX is phosphorylated at Ser139 after MNNG treatment and that this phosphorylation is critical for caspase‐independent programmed necrosis. Overall, our data shed new light in the mechanisms regulating programmed necrosis, elucidate a key nuclear partner of AIF, and uncover an AIF apoptogenic motif.     

Genetic variance between some Egyptian Date Palm cultivars using PCR-based markers with emphasis on the prevalence of Al wijam disease

Date Palm is one of the most important crops in Egypt. At present, Egypt ranked second in world date production. The objectives of this study are the identification the genetic variance between some local varieties of Date Palm, in line with the establishment of a molecular diagnostic method to study the aetiology and the prevalence of Al Wijam disease. Date palm plantations have been suffering from number of pests and diseases infestation, mainly due to Dubas Bug, Red Palm Weevil, Lesser Date moth, and Al Wijam disease. Genomic DNAs were extracted from 18 Date Palm cultivars collected from Date Palm Research Institute, ARC using three different extraction methods. Nine common cultivars (Zaghlool, Hayani, Oraibi, Samani, Sultan, Bent-Aisha, Amrey, Aglani, and Barhee) and nine Siwi cultivars (Siwi, Fryhee, Taktakt, Quaipe, Karama Ghazally, Helw Ghanem, Gorm Agazal, and Oshbeigel,) were used in this study. In order to determine the genetic polymorphism and discriminate between each of these cultivars, RAPD and ISSR analysis were conducted on the isolated DNA samples from each cultivar. DNA fingerprints of the studied cultivars were conducted using 10 RAPD and eight ISSR primers. Dendrograms representing genetic relationships as well as genetic similarity matrices were performed for the studied cultivars using the UPGMA (Unweighted Pair Group Method with Arithmetic Average). Furthermore, 40 date palm trees representing the studied cultivars were collected from El-Marazik, El-Badrasheen, El-Wahat, and Demiate Governorates to study the prevalence of Al-Wijam disease using the DNA hybridisation technique. Symptoms including retardation in terminal bud growth, whole crown of leaves (rosetting symptoms), and yellow longitudinal lines on the midribs were observed. Non-radioactive Dig-labeled probes specific for 16s rDNA region of virus like agents were used to detect the infected trees.     

Carbonic anhydrase inhibitors: Benzenesulfonamides incorporating cyanoacrylamide moieties are low nanomolar/subnanomolar inhibitors of the tumor-associated isoforms IX and XII

A series of benzenesulfonamides incorporating cyanoacrylamide moieties (tyrphostine analogues) have been obtained by reaction of sulfanilamide with ethylcyanoacetate followed by condensation with aromatic/heterocyclic aldehydes, isothiocyanates or diazonium salts. The new compounds have been investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4. 2.1.1), and more specifically against the cytosolic human (h) isoforms hCA I and II, as well as the transmembrane, tumor-associated ones CA IX and XII, which are validated antitumor targets. Most of the new benzenesulfonamides were low nanomolar or subnanomolar CA IX/XII inhibitors whereas they were less effective as inhibitors of CA I and II. The structure–activity relationship for this class of effective CA inhibitors is also discussed. Generally, electron donating groups in the starting aldehyde reagent favored CA IX and XII inhibition, whereas halogeno, methoxy and dimethylamino moieties led to very potent CA XII inhibitors.     

Validation of alternative methods for the analysis of drinking water and their application to Escherichia coli

In Europe, the Drinking Water Directive of the European Commission indicates which methods (most of which are CEN/ISO-standardized methods) should be used for the analysis of microbiological parameters (European Commission, Environment, Council Directive 98/83/EC of 3 November 1998). According to the Directive, alternative methods “may be used, providing it can be demonstrated that the results obtained are at least as reliable as those produced by the methods specified.” The prerequisite for the routine use of any alternative method is to provide evidence that this method performs equivalently to the corresponding reference method. In this respect, the ISO 16140 standard (ISO, ISO 16140. Microbiology of Food and Animal Feeding Stuffs—Protocol for the Validation of Alternative Methods, 2003) represents a key issue in generating such a procedure based on an interlaboratory study. A new statistical tool, called the accuracy profile, has been developed to better interpret the data. The study presented here is based upon the enumeration of Escherichia coli bacteria in water. The reference method may require up to 72 h to provide a confirmed result. The aim of this publication is to present data for an alternative method by which results can be obtained in 18 h (Colilert-18/Quanti-Tray) based upon defined substrate technology (DST). The accuracy profile is a statistical and graphical decision-making tool and consists of simultaneously combining, in a single graphic, β expectation tolerance intervals (β-ETIs) and acceptability limits (λ). The study presents the validation criteria calculated at the three levels of contamination used in the trial for a β equal to 80% and a λ equal to ±0.3 and combines the accuracy profiles of Escherichia coli for a λ of ±0.3 log₁₀ unit/100 ml, a λ of ±0.4 log₁₀ unit/100 ml, and a β of 80% or 90%. Several interesting conclusions can be drawn from these data. The accuracy profile method has been applied to the validation of the Colilert-18/Quanti-Tray method against reference method ISO 9308-1 (ISO, ISO 9308-1. Water Quality—Detection and Enumeration of Escherichia coli and Coliform Bacteria. Part 1. Membrane Filtration Method, 2000), using a β of 80% and a λ of 0.4; the alternative method can be validated between 1.00 and 2.05 log₁₀ units/100 ml, equivalent to 10 to 112 CFU/100 ml.