Search

Of the most common infectious diseases that occur mainly by uropathogenic Escherichia coli (UPEC) is urinary tract infections (UTIs). The purpose of this study was to investigate virulence factors, antibiotic resistance, and phylogenetic groups among UPEC strains isolated from patients with UTI in southern Iraq. A total of 100 UPEC isolates were collected from urine samples of UTI patients from various hospitals in southern Iraq, and confirmed by morphological and biochemical tests. Antimicrobial susceptibility testing on isolates was performed by disk diffusion method. Multiplex PCR technique was used to evaluate the phylogenetic groups and the presence of six virulence factor genes; type 1 fimbria (fimH), A-fimbrial adhesion (afa), hemolysin (hly), fimbrial adhesins P (papC), cytotoxic necrosis factor 1 (cnf1), and aerobactin (aer). The majority of isolates belonged to the phylogenetic groups of B2 (55%) and D (32%). The most prevalent virulence factors were fimH (96%), followed by aer (47%), papC (36%), cnf1 (17%), hly (15%), and afa (8%). Phenotypic testing showed that the isolates were most resistant to piperacillin, ticarcillin, amoxicillin/clavulanic acid (92%, 91%, and 88%, respectively) and most sensitive to amikacin and imipenem, respectively. The maximum antibiotic resistance and virulence factors were observed in the phylogenetic group B2. The results showed that the UPEC isolates had all six virulence factors with high frequency and the highest drug resistance. Besides, the results showed a direct relationship between virulence factors, gene diversity, phylogenetic background, and antimicrobial resistance in the UPEC isolates.

Background: Acinetobacter is one of the most important pathogens that causes a high prevalence of infection in clinical centers. Natural products are major sources of new anti-infective agents and considered as an alternative medicine for the treatment of infectious diseases. Objective: This study aims to evaluate the antibacterial activity of aqueous and methanol extract of Artemisia annua on the clinically isolated Acinetobacter and the combination of the plant extract with amikacin and imipenem. Methods: The aqueous and methanol extract of the aerial parts of this plant was prepared by maceration. Antibacterial activity was determined by the Broth microdilution method . The presence of adeI and adeB genes in Acinetobacter isolates was investigated. The combination effects of antibiotics were performed using the checkerboard method. The effect of plant extract on bacterial efflux pumps was also investigated. Results: MIC values of the methanol extract of A. annua were from 4.46 mg/ml to 8.92 mg/ml. The effects of the interaction of the plant extract with the amikacin and imipenem represent a significant synergistic influence. Findings indicated that the plant extract was able to inhibit the efflux pump remarkably. Conclusion: The combination of the plant extract with amikacin and imipenem can be used in the treatment of infections caused by antibiotic-resistant Acinetobacter and probably other infectious diseases.

Background: Carbapenem-resistant Acinetobacter baumannii strains are one of the most severe factors in hospital infection worldwide, in which the beta-lactamase enzyme is one of the main resistance mechanisms. Objectives: This study aimed to evaluate the presence of carbapenem-resistant beta-lactamase genes and determine antibiotic resistance patterns in the clinical isolates of A. baumannii from patients hospitalized in the Shahid Kamyab Hospital, Mashhad, Iran. Methods: Out of 286 collected isolates from patients hospitalized in Shahid Kamyab Hospital (from March 2017 to June 2017), 31 isolates were confirmed to be A. baumannii using biochemical tests. Antibiotic susceptibility testing was conducted using the disc diffusion method according to the CLSI standard protocols. The presence of beta-lactamase genes, namely blaVEB, blaPER, blaAmpC, blaVIM, blaIMP, blaSHV, and blaTEM, was detected using polymerase chain reaction. Results: In this study, 31 isolates were identified as A. baumannii, all of which revealed high resistance to ceftazidime, cefixime, ceftriaxone, meropenem, imipenem, cefotaxime and cephalexin. In this case, the lowest resistance (19.35%) was observed against polymixin B. Moreover, blaAmpC, blaTEM, blaSHV, blaPER, and blaVIM were observed in 93.54% (29), 51.61% (16), 48.38% (15), 41.93% (13), and 77% (24) of the isolates, respectively. However, blaVEB and blaIMP were observed in none of the isolates. Conclusions: The results showed high carbapenem resistance and high frequency of beta-lactamase resistance genes among the clinical isolates of A. baumannii.

Keratinases are enzymes with the most diverse sources and applications. Different forms of keratinase have been applied in environment and variety of industries, highlighting the necessity for novel potential keratinases, which could be applicable in variety of industries. Accordingly, the present study aimed to identify and characterize a novel keratinase producing bacterium with high potential in variety of industries. In the present study, the native isolate of Bacillus sp. FUM125 was isolated, identified and optimized for the keratinolytic activity. The keratinase was purified and characterized using biochemical assays. The Bacillus sp. FUM125 isolate was identified as Bacillus mojavensis R-OH-1 with 99.8% similarity. The isolate showed the maximum keratinolytic activity at pH of 8.5 after 24-hour incubation at 37°C (2.1-fold enzyme production). According to the biochemical analysis, the keratinase belonged to a serine protease family, whit 33.5 kDa molecular weight and was stable in a wide range of pH and temperature with maximum keratinolytic activity at 60°C and pH 8. Among the metal ions, K+, Ca2+, Na2+ and Mg2+ increased the enzyme activity. The activity was increased by the reducing agents of DTT and beta-mercaptoethanol. Based on the substrate profile findings, the enzyme was active in various soluble and insoluble substrates. The enzyme showed a half-life of 98 min in the optimal temperature and the ratio of keratinolytic:caseinolytic to be 0.95. Our enzyme with higher temperature and pH stability compared to existing commercial enzymes can be considered as a potential candidate for use in various industries.

Bromophenol blue (BPB)-doped nano-droplets are recognized as a synthesis of BPB dye and transparent dispersion of nano-droplets (ND), in a continuous phase of oils. In this regard, to discover the effect of ND size on nonlinear optical properties of BPB, a solution of BPB-doped ND with heptane oil and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as a surfactant has been prepared and therefore investigated with Z-scan technique. The consequences have revealed that the nonlinear refractive (NLR) index, of the BPB-doped ND has been improved by comparison with BPB aqueous solution. The second-order hyperpolarizability of the BPB-doped ND has been also reduced subsequent a reduction in ND size owing to reducing dye aggregation. Moreover, the BPB-doped ND in the company of laser radiation has been utilized in order to study of antibacterial photodynamic therapy of Staphylococcus aureus (S. aureus) by nonlinear absorption. As a consequence, the bacteria colonies have been also exceedingly declined in the group treated with the BPB-doped ND.

Biosynthesis of silver nanoparticles (AgNPs) by marine bacteria especially luminescent Vibrio species is least investigated. In this study, AgNPs were first synthesized by the culture supernatant of a luminescent bacterium (Vibrio sp. B4L) and then, the prepared samples were characterized employing several techniques. The antibacterial activity of the AgNPs was investigated against Escherichia coli and Staphylococcus aureus using disk diffusion agar and broth microdilution methods. The growth curve, Reactive Oxygen Species (ROS) formation, and Lactate Dehydrogenase (LDH) activity of the samples were measured along with Field Emission Scanning Electron Microscopy (FESEM) observation and inhibition of biofilm formation. Dynamic light scattering (DLS) analysis showed that the average particle size of the synthesized AgNPs was in the range of about 32.67–107.18 nm and the polydispersity index (PDI) of 0.1120 indicated the formation of monodispersed particles. The average zeta potential of AgNPs obtained −36.15 mV, showing the high stability of biosynthetic nanoparticles. Antibacterial studies indicated that not only the AgNPs had antibacterial activity but also increased the antibacterial properties of tetracycline when used in combination. ROS production was enhanced in a dose-dependent manner. A high difference in LDH activities was found between AgNPs treated cells and the control group. FESEM images revealed membrane disruption and lysis in AgNPs treated cells. The formation of E. coli biofilm was 100% inhibited at 62.5 µg/ml showing that our bacteriogenic AgNPs can be a potential alternative remedies for controlling antibiotic-resistant pathogens.

Background and Objectives: In recent years, reports of Acinetobacter strains resistant to all known antibiotics have caused a great concern in medical communities. Overexpression of efflux pumps is one of the major causes of resistance in bacteria. The aim of this study was to investigate the role of efflux pumps in conferring resistance to imipenem in clinically important Acinetobacter spp; Acinetobacter baumannii and Acinetobacter lwoffii. Materials and Methods: A total number of 46 clinical Acinetobacter isolates, including 33 A. baumannii and 13 A. lwoffii isolates, previously collected from Shahid Kamyab and Ghaem hospitals of Mashhad, Iran were used in this study. Imipenem susceptibility testing was carried out by the disc diffusion method. Imipenem minimum inhibitory concentration (MIC) for resistant Acinetobacter isolates were determined both in the presence and absence of the efflux pumps inhibitor, carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Results: Resistance to imipenem was observed in 38 isolates including 30 A. baumannii and 8 A. lwoffii isolates. Experiments in the presence of CCCP showed a 2 to 16384 fold reduction in imipenem MICs in 14 A. baumannii and 2 A. lwoffii isolates. Conclusion: The results obtained showed high levels of resistance to imipenem and contribution of efflux pumps in conferring resistance in both Acinetobacter species in this study. Moreover, imipenem efflux mediated resistance highlights the importance of this mechanism not only in A. baumannii but also in non-baumannii Acinetobacter Spp. which have been neglected in antibiotic resistance studies.

Acinetobacter species are defined as multidrug-resistant pathogens and the development of resistance against antimicrobials is a major problem in the treatment of infections caused by them. This study aimed to evaluate the antibacterial activity of aqueous and methanol extracts of Salvia chorassanica and Artemisia khorassanica on multidrug-resistant Acinetobacter isolates and also examining the interaction of the methanol extract of the plants with the combination of amikacin and imipenem. First, the presence of adeI and adeB genes in bacterial isolates was investigated. The aqueous and methanol extracts of the leaves of the plants were prepared by ‏Maceration method. Minimum Inhibition Concentration (MIC) values were determined to evaluate the antibacterial activities of plant extracts and antibiotics. Combined effects of the antibiotics with plant extracts were performed using the checkerboard method. The accumulation assay was used to examine the inhibitory effects of plant extracts on the bacterial efflux pump. MIC results indicated that the methanol extracts were effective against Acinetobacter species. FICI values indicated that the combination of antibiotics with methanol plant extracts improves bacterial sensitivity to antibiotics. The extracts also exhibited efflux pump inhibitory activities. Consequently, combination of the plant extracts with antibiotics could enhance the antibiotic susceptibility of resistant pathogens.

Background and Objectives: In recent years, reports of Acinetobacter strains resistant to all known antibiotics have caused a great concern in medical communities. Overexpression of efflux pumps is one of the major causes of resistance in bacteria. The aim of this study was to investigate the role of efflux pumps in conferring resistance to imipenem in clinically important Acinetobacter spp; Acinetobacter baumannii and Acinetobacter lwoffii. Materials and Methods: A total number of 46 clinical Acinetobacter isolates, including 33 A. baumannii and 13 A. lwoffii isolates, previously collected from Shahid Kamyab and Ghaem hospitals of Mashhad, Iran were used in this study. Imipenem susceptibility testing was carried out by the disc diffusion method. Imipenem minimum inhibitory concentration (MIC) for resistant Acinetobacter isolates were determined both in the presence and absence of the efflux pumps inhibitor, carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Results: Resistance to imipenem was observed in 38 isolates including 30 A. baumannii and 8 A. lwoffii isolates. Experiments in the presence of CCCP showed a 2 to 16384 fold reduction in imipenem MICs in 14 A. baumannii and 2 A. lwoffii isolates. Conclusion: The results obtained showed high levels of resistance to imipenem and contribution of efflux pumps in conferring resistance in both Acinetobacter species in this study. Moreover, imipenem efflux mediated resistance highlights the importance of this mechanism not only in A. baumannii but also in non-baumannii Acinetobacter Spp. which have been neglected in antibiotic resistance studies.

In the last few years, gold nanoparticle biosensors have been developed for rapid, precise, easy and inexpensive with high specificity and sensitivity detection of human, plant and animal pathogens. Klebsiella pneumoniae serotype K2 is one of the common gram-negative pathogens with high prevalence. Therefore, it is essential to provide the effective and exclusive method to detect the bacteria. Klebsiella pneumoniae serotype K2 strain ATCC9997 genomic DNA was applied to establish the detection protocol either with thiol-capped oligonucleotide probes and gold nanoparticles or polymerase chain reaction based on K2A gene sequence. In the presence of the genomic DNA and oligonucleotide probes, a change in the color of gold nanoparticles and maximum changes in wavelength at 550-650 nm was achieved. In addition, the result showed specificity of 15 × 105 CFU/mL and 9 pg/μL by gold nanoparticles probes. The lower limit of detection obtained by PCR method was 1 pg/μL. Moreover, results demonstrated a great specificity of the designed primers and probes for colorimetric detection assay and PCR. Colorimetric detection using gold nanoparticle probe with advantages such as the lower time required for detection and no need for expensive detection instrumentation compared to the biochemical and molecular methods could be introduced for rapid, accurate detection of the bacteria.

Background and Objectives: Traditional culture methods for detection of food-borne pathogens, a major public health problem, are simple, easily adaptable and very practical, but they can be laborious and time consuming. In this study, we eliminated culturing steps by developing a new separation method and therefore, decreased the detection time of food-borne pathogens (Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes) to a few hours. Materials and Methods: We used alkaline water and different alkaline buffers to elute bacteria from the lettuce surface as a model for ready-to-eat vegetables. Buffers used were as follows: 1) 0.05 M glycine; 2) 0.05 M glycine -100 mM Tris base -1% (w/v) beef extract; 3) buffer peptone water; 4) buffer phosphate saline. Buffers were adjusted to pH of 9, 9.5 and 10. In order to elute the bacteria, the lettuce pieces were suspended into buffers and shacked for 30, 45 and 60 min. Moreover, a multiplex PCR method for the simultaneous detection of food-borne pathogens was performed. Results: The results showed that buffer peptone water at pH 9.5 for 45 min have high ability to elute bacteria from the lettuce surface and the bacteria can be detected using multiplex PCR. Conclusion: We developed a new rapid and efficient method for simultaneous separation of food-borne pathogens. This method eliminates culturing stages and permits the detection and identification of target pathogens in a few hours.

Dye-doped droplets are known as mixtures of dyes with uniform solutions of water droplets in a continuous phase of oils with surfactants. To observe the relationship between water droplet structures and surfactant types on optical properties of dyes, a mixture of methyl orange (MO)-doped droplet prepared with benzane and hexane as oils and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as a surfactant was thus examined using Z-scan instrument, spectrophotometer, and fluorimeter in the present study. The findings revealed that nonlinear refractive (NLR) index, nonlinear absorption (NLA) coefficient, as well as fluorescence intensity of the MO had enhanced following a reduction in the droplet water content induced by changes in the non-centrosymmetric charge density distribution of this pH indicator. Moreover, the MO-doped droplet in a continuous phase of benzene investigated by 1H nuclear magnetic resonance (NMR) spectroscopy indicated that the MO had been located in the droplet in the vicinity of the hydrophilic part of the surfactant. Furthermore, the MO-doped droplets along with laser radiation were employed to perform antibacterial photodynamic therapy (APDT) of Staphylococcus aureus (S. aureus). It was ultimately concluded that the bacteria colony had also extremely diminished in the group treated by the MO-doped droplet.

[ES]El objetivo del presente trabajo fue estudiar el papel de Cfh3p en la celda síntesis de la pared y en la morfogénesis en Schizosaccharomyces pombe., [EN]The objective of the present work was to study the role of Cfh3p in cell wall synthesis and in morphogenesis in Schizosaccharomyces pombe.

Potassium dichromate (KD) is a common inorganic pigment used as a photosensitizer (PS) for photodynamic therapy (PDT). Numerous works in this area have so far reflected on organic dye and its colloidal system with linear absorption in PDT, while a few studies have been completed on potentials of nonlinear absorption (NLA) of inorganic KD for this type of treatment. Therefore, absorbance, nuclear magnetic resonance (NMR), and nonlinear optical (NLO) properties of KD and its formulations were described in detail. The pigment was also found to be positioned within the inner part of the droplet prepared with water, oil, and surfactant. The impact associated with the length of hydrocarbon-chain of anionic surfactant micelles and reverse micelles (RMs) on the NLO properties of KD was further investigated. The results revealed that the pigment had more interactions with the micelles prepared with a small-length-scale surfactant. The NLA and the second-order hyper-polarizabilities of KD were correspondingly proportional to the size of the RMs in an inverse manner. Moreover, encapsulation of the pigment in the RMs led to a reduction in the aggregation of the pigment and subsequently increased their NLA. Quantum calculations have been done to achive optimized geometry, dipole moment and band gap of KD and dimer of KD (2KD). It was demonstrated that using KD in a smaller size of RMs as PSs along with NLA via laser irradiation (LI) could be a very efficient method for treatment of Staphylococcus aureus (S.aureus).

Background: The development of multidrug-resistant Acinetobacter species has created serious problems in nosocomial infections. Understanding the underlying resistance mechanisms and their significance in conferring resistance to different antibiotics is the first step to develop strategies for fighting or reversing the current resistance. Objectives: The aim of this study was to investigate the role of efflux pumps in decreasing susceptibility to amikacin in Acinetobacter clinical isolates. Methods: Forty-six clinical Acinetobacter isolates were collected from 2 teaching hospitals of Mashhad, Iran. Susceptibility testing was conducted by the disc diffusion method. Amikacin minimum inhibitory concentration (MIC) for resistant Acinetobacter isolates was determined according to the Clinical and Laboratory Standards Institute (CLSI) guidelines either with or without the efflux pumps inhibitor, carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Conventional polymerase chain reaction (PCR) was used to analyze the presence of pump genes. Results: Acinetobacter isolates were identified as 2 species; Acinetobacter baumannii and A. lwoffii. Susceptibility testing showed high levels of resistance to amikacin in 27 isolates, including both A. baumannii and A. lwoffii, among which 20 A. baumannii isolates showed a 2- to 524288-fold reduction in amikacin MIC in the presence of CCCP, while no reduction occurred in amikacin MIC in resistant A. lwoffii isolates. The PCR results showed high frequencies of adeB, abeM, and adeI genes in Acinetobacter isolates yet the adeE gene was not found in any of the isolates. Conclusions: The obtained results indicated the importance of efflux pumps in conferring resistance to amikacin in clinical isolates of A.baumannii, yet not in A. lwoffii.

The effect of length scale of triblock oil-soluble polymer (poly (e-caprolactone)–poly butadiene-poly (e-caprolactone)) (PCL-PB-PCL) on the properties of a water-in-oil (W/O) droplet microemulsion (R ~ 5.5 nm) has been studied as a function of the amount of added telechelic polymer. Small-angle X-ray scattering (SAXS) measurements show that the size of the droplets is not affected by the polymer addition but it induces attractive interactions at low concentration and repulsive ones at high polymer content. Measurements of the diffusion coefficient by dynamic light scattering (DLS) show different relaxations in mixed systems. The fast diffusion coefficient increases with increase in polymer concentration. At higher polymer content, the network formation leads to an additional slow relaxation mode in DLS that can be related to the formation of clusters of microemulsion droplets interconnected by the polymer. The collective diffusion of slow relaxations decreases with increase of polymer concentrations.

In the study, an eco-friendly synthesis of silver nanoparticles (AgNPs) has been reported using aqueous extract of Scrophularia striata flower. The extract acts as reducing as well as stabilizing agent. To obtain the optimized conditions for synthesis of AgNPs, the effect of process variables such as extract concentration, concentration ratio of the reactants and time were studied using UV-Vis spectroscopy. The UV-Vis results showed a peak at 440 nm corresponding to the surface plasmon resonance in the optimized conditions (10% extract concentration, 1 : 1.5 concentration ratio of the reactants and time of 24 h). The synthesized AgNPs were also characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). According to the XRD patterns, the size of the AgNPs was calculated in the range of 8—12nm. The FESEM images showed the spherical shape of AgNPs. The FTIR spectrum showed the presence of various functional groups such as hydroxyl, amine and carbonyl groups. Finally, the antibacterial activity of the synthesized AgNPs was evaluated against Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). The results showed that the colloidal solution of AgNPs has antibacterial activity against both different strains of bacteria.

In this study the silver nanoparticles (AgNPs) were synthesized by reduction of silver ions using benzoin as a radical initiator under UV light. Polyvinyl alcohol (PVA) was used as a stabilizing agent. The AgNPs were characterized with UV-Vis spectrophotometry, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and FT-IR. The results exhibited the spherical shape of nanoparticles with size of 20–30 nm. The synthesized AgNPs were evaluated for their antibacterial activities against the Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Two types of bacteria were effectively inhibited by synthesized AgNPs.

In this paper we show that in Schizosaccharomyces pombe, mating-specific cell adhesion is dependent on the exocyst subunit Sec8p, but independent of the exocyst subunit Exo70p. In the absence of Exo70p, the forespore membrane does not develop properly and the leading edge protein Meu14p is abnormally distributed. Additionally, the spindle pole body is aberrant in a significant number of exo70Δ asci. In both the sec8-1 and the exo70Δ mutants, the development of the spore cell wall is impaired. These results show that different steps of sexual development are differentially regulated by the exocyst and suggest the existence of exocyst subcomplexes with distinct roles in mating.

El pdf del artículo es la versión pre-print.-- et al., In fungi, success of mating requires that both cells agglutinate, modify their extracellular envelopes, and fuse their plasma membranes and nuclei to produce a zygote. Here we studied the role of the Schizosaccharomyces pombe Dni1 protein in the cell fusion step of mating. Dni1p is a tetraspan protein bearing a conserved cystein motif similar to that present in fungal claudin-related proteins. Dni1p expression is induced during mating and Dni1p concentrates as discrete patches at the cell-cell contact area and along the mating bridge. Proper Dni1p localization depends on Fus1p, actin and integrity of lipid rafts. In dni1Δ mutants, cell differentiation and agglutination are as efficient as in the wild-type strain, but cell fusion is significantly reduced at temperatures above 25°C. We found that the defect in cell fusion was not associated with an altered cytoskeleton, with an abnormal distribution of Fus1p, or with a defect in calcium accumulation, but with a severe disorganization of the plasma membrane and cell wall at the area of cell-cell contact. These results show that Dni1p plays a relevant role in co-ordinating membrane organization and cell wall remodelling during mating, a function that has not been described for other proteins in the fission yeast. © 2009 Blackwell Publishing Ltd., This work has been supported by Grant BFU2007-61866 from the CICYT and Grants SA128/04, SA104A/07 and GR231 from the Junta de Castilla y León, Spain. J.Á. C.-R. and R.M.-G. were supported by fellowship from the MEC, Spain, and M.R.S. was supported by a fellowship from the Government of Iran.

10 páginas, 6 figuras.-- El pdf del artículo es la versión post-print., In Schizosaccharomyces pombe, Bgs1/Cps1p is a β(1,3)-glucan synthase required for linear β(1,3)-glucan synthesis and primary septum formation. Here, we have studied the regulation of Bgs1p by Cfh3/Chr4p, a member of a family of conserved adaptor proteins, which resembles the chitin synthase regulator Chs4p from Saccharomyces cerevisiae and Candida albicans. cfh3Δ cells showed a genetic interaction with cps1-191, and Cfh3p co-immunoprecipitated with Bgs1/Cps1p. In the absence of cfh3+, cells were more sensitive to digestion by glucanases, and both Calcofluor staining and glucan synthesis were reduced. We found that in a wild-type strain, β(1,3)-glucan synthesis was reduced under stress conditions. In the cfh3Δ, cps1-191, and cfh3Δ cps1-191 strains, β(1,3)-glucan synthesis was further reduced, and growth was impaired under stress conditions, suggesting that Cfh3p and Bgs1p might play a role in ensuring growth in unfavorable environments. In a cfh3Δ mutant, Bgs1p was delocalized when the cells were distressed, but a blockade in endocytosis prevented this delocalization. Finally, we found that the SEL1 repeats are required for Cfh3p function. These results show that Cfh3p is a regulatory protein for Bgs1p and that its function is particularly necessary when the cells are undergoing stress., This work was supported by Grant BFU2007-61866 from the CICYT and Grants SA104A/07 and GR231 from the Junta de Castilla y León, Spain.

The involvement of Schizosaccharomyces pombe prm1+ in cell fusion during mating and its relationship with other genes required for this process have been addressed. S. pombe prm1Δ mutant exhibits an almost complete blockade in cell fusion and an abnormal distribution of the plasma membrane and cell wall in the area of cell-cell interaction. The distribution of cellular envelopes is similar to that described for mutants devoid of the Fig1-related claudin-like Dni proteins; however, prm1+ and the dni+ genes act in different subpathways. Time-lapse analyses show that in the wild-type S. pombe strain, the distribution of phosphatidylserine in the cytoplasmic leaflet of the plasma membrane undergoes some modification before an opening is observed in the cross wall at the cell- cell contact region. In the prm1Δ mutant, this membrane modification does not take place, and the cross wall between the mating partners is not extensively degraded; plasma membrane forms invaginations and fingers that sometimes collapse/retract and that are sometimes strengthened by the synthesis of cell-wall material. Neither prm1Δ nor prm1Δ dniΔ zygotes lyse after cell-cell contact in medium containing and lacking calcium. Response to drugs that inhibit lipid synthesis or interfere with lipids is different in wild-type, prm1Δ, and dni1Δ strains, suggesting that membrane structure/organization/dynamics is different in all these strains and that Prm1p and the Dni proteins exert some functions required to guarantee correct membrane organization that are critical for cell fusion. © 2014 by the Genetics Society of America., Financial support to H.V.M. from the Comisión Interministerial de Ciencia Y Tecnología (Spain)/European Union Fondo Europeo de Desarrollo Regional program (grant BFU2010-15085) made this work possible. M.A.C. and N.d.L were supported by Formación de Personal Universitario fellowships from the Ministry of Science, and M.H. was supported by a Junta de Ampliación de Estudios predoctoral fellowship from the Consejo Superior de Investigaciones Científicas, Spain.

This is an open-access article distributed under the terms of the Creative Commons Attribution License., In yeast, cytokinesis requires coordination between nuclear division, acto-myosin ring contraction, and septum synthesis. We studied the role of the Schizosaccharomyces pombe Bgs1p and Cfh3p proteins during cytokinesis under stress conditions. Cfh3p formed a ring in the septal area that contracted during mitosis; Cfh3p colocalized and co-immunoprecipitated with Cdc15p, showing that Cfh3p interacted with the contractile acto-myosin ring. In a wild-type strain, a significant number of contractile rings collapsed under stress conditions and this number increased dramatically in the cfh3Δ, bgs1cps1-191, and cfh3Δ bgs1/cps1-191. Our results show that after osmotic shock Cfh3p is essential for the stability of the (1,3) glucan synthase Bgs1p in the septal area, but not at the cell poles. Finally, cells adapted to stress; they repaired their contractile rings and re-localized Bgs1p to the cell surface some time after osmotic shock. A detailed analysis of the cytokinesis machinery in the presence of KCl revealed that the actomyosin ring collapsed before Bgs1p was internalized, and that it was repaired before Bgs1p re-localized to the cell surface. In the cfh3Δ, bgs1/cps1-191, and cfh3Δ bgs1/cps1-191 mutants, which have reduced glucan synthesis, the damage produced to the ring had stronger consequences, suggesting that an intact primary septum contributes to ring stability. The results show that the contractile actomyosin ring is very sensitive to stress, and that cells have efficient mechanisms to remedy the damage produced in this structure. © 2012 Sharifmoghadam et al., Financial support to the Instituto de Biología Funcional y Genómica (IBFG) from the Fundación Ramón Areces and to our group from the Comisión Interministerial de Ciencia y Tecnología (CICYT) (Spain)/European Union FEDER (Fondo Europeo de Desarrollo Regional) program (grant BFU2007-61866) made this work possible. Dr. Curto was supported by a contract for training in research and technological innovation by Junta de Castilla y León and by Formación de Personal Investigador (FPU) fellowship. Dr. de León and Dr. Hoya were supported by FPU and Junta de Ampliación de Estudios (JAE)-PREDOC fellowships from the Ministry of Science and Consejo Superior de Investigaciones Científicas (CSIC), Spain, respectively.

El pdf del artículo es la versión pre-print., Chs5p is a component of the exomer, a coat complex required to transport the chitin synthase Chs3p from the trans-Golgi network to the plasma membrane. The Chs5p N-terminal region exhibits fibronectin type III (FN3) and BRCT domains. FN3 domains are present in proteins that mediate adhesion processes, whereas BRCT domains are involved in DNA repair. Several fungi-including Schizosaccharomyces pombe, which has no detectable amounts of chitin-have proteins similar to Chs5p. Here we show that the FN3 and BRCT motifs in Chs5p behave as a module that is necessary and sufficient for Chs5p localization and for cargo delivery. The N-terminal regions of S. cerevisiae Chs5p and S. pombe Cfr1p are interchangeable in terms of Golgi localization, but not in terms of exomer assembly, showing that the conserved function of this module is protein retention in this organelle and that the interaction between the exomer components is organism-specific. © 2010 Springer Basel AG., This work has been supported by grants BFU2007- 61866 from the CICYT and GR231 from the Junta de Castilla y León, Spain. NdL was supported by a fellowship from the Spanish Ministry of Science. RMG and PBS were supported by postgraduate I3P fellowships from the Spanish council of research (CSIC).

In this paper we show that in Schizosaccharomyces pombe, mating-specific cell adhesion is dependent on the exocyst subunit Sec8p, but independent of the exocyst subunit Exo70p. In the absence of Exo70p, the forespore membrane does not develop properly and the leading edge protein Meu14p is abnormally distributed. Additionally, the spindle pole body is aberrant in a significant number of exo70Delta asci. In both the sec8-1 and the exo70Delta mutants, the development of the spore cell wall is impaired. These results show that different steps of sexual development are differentially regulated by the exocyst and suggest the existence of exocyst subcomplexes with distinct roles in mating.

El pdf del artículo es la versión pre-print., In fungi, cell adhesion is required for flocculation, mating and virulence, and it is mediated by covalently bound cell wall proteins termed adhesins. Map4, an adhesin required for mating in Schizosaccharomyces pombe, is N-glycosylated and O-glycosylated, and is an endogenous substrate for the mannosyl transferase Oma4p. Map4 has a modular structure with an N-terminal signal peptide, a serine and threonine (S/T)-rich domain that includes nine repeats of 36 amino acids (rich in serine and threonine residues, but lacking glutamines), and a C-terminal DIPSY domain with no glycosylphosphatidyl inositol (GPI)-anchor signal. Map4 can be extracted from cell walls with SDS/mercaptoethanol sample buffer or with mild alkali solutions. After extensive extraction with hot sample buffer, no more protein can be released by β-glucanases or alkali. Additionally, none of the cysteine residues of the protein is required for its retention at the cell wall. These results show that Map4 is not directly bound to β-glucans and point to the existence of alkali- and SDS/mercaptoethanol-sensitive linkages between cell wall proteins. The N-terminal S/T-rich regions are required for cell wall attachment, but the C-terminal DIPSY domain is required for agglutination and mating in liquid and solid media. © 2008 The Authors., This work has been supported by Grant BFU2007-61866 from the CICYT and Grant SA104A/07 from the Junta de Castilla y León, Spain. M.R.S. is supported by a fellowship from the Government of Iran.

This is an open-access article distributed under the terms of the Creative Commons Attribution License., The regulation of cell wall synthesis by the clathrin light chain has been addressed. Schizosaccharomyces pombe clc1Δ mutant was inviable in the absence of osmotic stabilization; when grown in sorbitol-supplemented medium clc1Δ cells grew slowly, formed aggregates, and had strong defects in morphology. Additionally, clc1Δ cells exhibited an altered cell wall composition. A mutant that allowed modulating the amount of Clc1p was created to analyze in more detail the dependence of cell wall synthesis on clathrin. A 40% reduction in the amount of Clc1p did not affect acid phosphatase secretion and bulk lipid internalization. Under these conditions, β(1,3)glucan synthase activity and cell wall synthesis were reduced. Also, the delivery of glucan synthases to the cell surface, and the secretion of the Eng1p glucanase were defective. These results suggest that the defects in the cell wall observed in the conditional mutant were due to a defective secretion of enzymes involved in the synthesis/remodelling of this structure, rather than to their endocytosis. Our results show that a reduction in the amount of clathrin that has minor effects on general vesicle trafficking has a strong impact on cell wall synthesis, and suggest that this is the reason for the lethality of clc1Δ cells in the absence of osmotic stabilization., Financial support to our group from the MICINN (http://www.idi.mineco.gob.es/. Spain)/European Union FEDER program (grant BFU2010-15085) made this work possible. NdL and MAC were supported by FPU fellowships from the Ministry of Science, and MH was supported by a JAE-PREDOC fellowship from Consejo Superior de Investigaciones Cientificas, Spain.