scholarly journals 4-Hydroxyphenylpyruvate Dioxygenase Thermolability Is Responsible for Temperature-Dependent Melanogenesis inAeromonas salmonicidasubsp.salmonicida

2018 ◽  
Vol 85 (1) ◽  
Author(s):  
Yunqian Qiao ◽  
Jiao Wang ◽  
He Wang ◽  
Baozhong Chai ◽  
Chufeng Rao ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Cold Water ◽  
Biological Significance ◽  
Adaptive Strategy ◽  
Homogentisic Acid ◽  
Aeromonas Salmonicida ◽  
Culture Temperature ◽  
Temperature Dependent ◽  
Content Type ◽  
Water Fish

ABSTRACTAeromonas salmonicidasubsp.salmonicidais a major pathogen affecting fisheries worldwide and is a well-known pigmented member of theAeromonasgenus. This subspecies produces melanin at ≤22°C. However, melanogenesis decreases as the culture temperature increases and is completely suppressed at 30°C to 35°C, while bacterial growth is unaffected. The mechanism and biological significance of this temperature-dependent melanogenesis remain unclear. Heterologous expression of anA. salmonicidasubsp.salmonicida4-hydroxyphenylpyruvate dioxygenase (HppD), the most critical enzyme in the homogentisic acid (HGA)-melanin synthesis pathway, results in thermosensitive pigmentation inEscherichia coli, suggesting that HppD plays a key role in this process. In this study, we demonstrated that the thermolability of HppD is responsible for the temperature-dependent melanization ofA. salmonicidasubsp.salmonicida. Substitutions of three residues, S18T, P103Q, and L119P, inA. salmonicidasubsp.salmonicidaHppD increased the thermostability of this enzyme and resulted in temperature-independent melanogenesis. Moreover, the replacement of the corresponding residues in HppD fromAeromonas mediastrain WS, which forms pigment independent of temperature, with those ofA. salmonicidasubsp.salmonicidaHppD resulted in thermosensitive melanogenesis. A structural analysis suggested that mutations at these sites, especially at position P103, strengthen the secondary structure of HppD and greatly improve its thermal stability. Additionally, we found that the HppD sequences of allA. salmonicidasubsp.salmonicidaisolates were identical and that two of the three residues were clearly distinct from those of otherAeromonasstrains.IMPORTANCEAeromonas salmonicidasubsp. salmonicidais the causative agent of furunculosis, a bacterial septicemia of cold-water fish of theSalmonidaefamily. Although otherAeromonasspecies can produce melanin,A. salmonicidasubsp.salmonicidais the only member of this genus that has been reported to exhibit temperature-dependent melanization. Here, we demonstrated that thermosensitive melanogenesis inA. salmonicidasubsp.salmonicidastrains is due to the thermolability of 4-hydroxyphenylpyruvate dioxygenase (HppD). Additionally, we confirmed that this thermolabile HppD exhibited higher activity at low temperatures than its mesophilic homologues, suggesting this as an adaptive strategy of this enzyme to the psychrophilic lifestyle ofA. salmonicidasubsp.salmonicida. The strictly conservedhppDsequences amongA. salmonicidasubsp.salmonicidaisolates and the specific possession of P103 and L119 residues could be used as a reference for the identification ofA. salmonicidasubsp.salmonicidaisolates.

scholarly journals 4-hydroxyphenylpyruvate dioxygenase thermolability is responsible for temperature-dependent melanogenesis inAeromonas salmonicidasubsp.salmonicida

2018 ◽  
Author(s):  
Yunqian Qiao ◽  
Jiao Wang ◽  
He Wang ◽  
Baozhong Chai ◽  
Chufeng Rao ◽  
...  
Keyword(s):  
Cold Water ◽  
Biological Significance ◽  
Adaptive Strategy ◽  
Aeromonas Salmonicida ◽  
Temperature Dependent ◽  
Ideal Model ◽  
Melanin Production ◽  
Water Fish ◽  
Insight Into

AbstractAeromonas salmonicidasubsp.salmonicida(A.s.s) is a major pathogen affecting fisheries worldwide. It is a well-known member of the pigmentedAeromonasspecies, which produces melanin at ≤ 22 °C. However, melanogenesis decreases as the culture temperature increases and is completely suppressed at 30-35 °C while bacterial growth is not affected. The mechanism and biological significance of this temperature-dependent melanogenesis are not clear. Heterologous expression of anA.s.s.4-hydroxyphenylpyruvate dioxygenase (HppD), the most crucial enzyme in the HGA-melanin synthesis pathway, results in thermosensitive pigmentation inEscherichia coli, suggesting that HppD plays a key role in this process. In the current study, we demonstrated that the extreme thermolability of HppD is responsible for the temperature-dependent melanization ofA.s.s.Substitutions in three residues, Ser18, Pro103, or Leu119 of HppD fromA.s.sincreases the thermolability of this enzyme and results in temperature-independent melanogenesis. Moreover, replacing the corresponding residues of HppD fromAeromonasmedia strain WS, which forms pigment independent of temperature, with those ofA.s.sHppD leads to thermosensitive melanogenesis. Structural analysis suggested that mutations at these sites, especially at position P103, can strengthen the secondary structure of HppD and greatly improve its thermal stability. In addition, we found that HppD sequences of allA.s.sisolates are identical and that two of the three residues are completely conserved withinA.s.sisolates, which clearly distinguishes these from otherAeromonasstrains. We suggest that this property represents an adaptive strategy to the psychrophilic lifestyle ofA.s.s.ImportanceAeromonas salmonicidasubsp.salmonicida(A.s.s) is the causative agent of furunculosis, a bacterial septicemia of cold water fish of theSalmonidaefamily. As it has a well-defined host range,A.s.shas become an ideal model to investigate the co-evolution of host and pathogen. For many pathogens, melanin production is associated with virulence. Although other species ofAeromonascan produce melanin,A.s.sis the only member of this genus that has been reported to exhibit temperature-dependent melanization. Here we demonstrate that thermosensitive melanogenesis inA.s.sstrains is due to the thermolability of 4-hydroxyphenylpyruvate dioxygenase (HppD). The strictly conservedhppDsequences amongA.s.sand the exclusive thermosensitive pigmentation of these strains might provide insight into the role of melanin in the adaptation to a particular host, and offer a novel molecular marker to readily differentiateA.s.sstrains from otherA. salmonicidasubspecies andAeromonasspecies.

scholarly journals The effects of environmental temperature on the properties of myofibrillar adenosine triphosphatase from various species of fish

1973 ◽  
Vol 133 (4) ◽  
pp. 735-738 ◽  
Author(s):  
Ian A. Johnston ◽  
Neil Frearson ◽  
Geoffrey Goldspink
Keyword(s):  
Low Temperatures ◽  
Half Life ◽  
Adenosine Triphosphatase ◽  
Environmental Temperature ◽  
Cold Water ◽  
Warm Water ◽  
Adenosine Triphosphatase Activity ◽  
Water Fish ◽  
Different Temperatures ◽  
Myotomal Muscle

1. Myofibrillar adenosine triphosphatase (ATPase) activities were measured for white myotomal muscle of 19 species of fish. 2. The activity was measured at different temperatures and after periods of preincubation at 37°C. 3. The inactivation half-life at 37°C depended on environmental temperature, increasing as the temperature increased. 4. Cold-water fish had higher myofibrillar adenosine triphosphatase activity at low temperatures than had warm-water fish. 5. The significance of these results is discussed.

scholarly journals A Novel Restriction-Modification System Is Responsible for Temperature-Dependent Phage Resistance in Listeria monocytogenes ECII

2012 ◽  
Vol 78 (6) ◽  
pp. 1995-2004 ◽  
Author(s):  
Jae-Won Kim ◽  
Vikrant Dutta ◽  
Driss Elhanafi ◽  
Sangmi Lee ◽  
Jason A. Osborne ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Low Temperatures ◽  
Phage Resistance ◽  
Type Ii ◽  
Temperature Dependent ◽  
Epidemic Clone ◽  
Modification System ◽  
Content Type ◽  
Restriction Modification System ◽  
Restriction Modification

ABSTRACTListeria monocytogenesepidemic clone II (ECII) strains are unusual in being completely resistant to phage when grown at low temperatures (≤30°C). In the current study we constructed and characterized amariner-based mutant (J46C) of the ECII strain H7550-CdSthat lacked temperature-dependent resistance to phage. The transposon was localized in LMOh7858_2753 (open reading frame [ORF] 2753), a member of a 12-ORF genomic island unique to ECII strains. ORF 2753 and ORF 2754 exhibited homologies to restriction endonucleases and methyltransferases associated with type II restriction-modification (RM) systems.In silico-based predictions of the recognition site for this putative RM system were supported by resistance of DNA from ECII strains to digestion by BfuI, a type II restriction enzyme specific for GTATCC (N6/5). Similarly to J46C, a mutant harboring an in-frame deletion of ORF 2753 was susceptible to phage regardless of temperature of growth (25°C or 37°C). Genetic complementation restored phage resistance in 25°C-grown cells of ORF 2753 mutants. Reverse transcription (RT) and quantitative real-time PCR data suggested enhanced transcription of ORF 2753 at low temperatures (≤25°C) compared to 37°C. In contrast, available transcriptional data suggested that the putative methyltransferase (ORF 2754) was constitutively expressed at all tested temperatures (4 to 37°C). Thus, temperature-dependent resistance ofL. monocytogenesECII to phage is mediated by temperature-dependent expression of the restriction endonuclease associated with a novel RM system (LmoH7) unique to this epidemic clone.

DEVELOPMENT OF AN INDICATION SCHEME FOR AEROMONAS SALMONICIDA BACTERIA USING BACTERIOPHAGES

2020 ◽  
pp. 184-190
Author(s):  
N. I Molofeeva ◽  
◽  
А.I. Kaldyrkaev ◽  
А.G. Shestakov ◽  
◽  
...  
Keyword(s):  
Causative Agent ◽  
Cold Water ◽  
External Environment ◽  
Aeromonas Salmonicida ◽  
Distribution Area ◽  
The World ◽  
Water Fish ◽  
Ulyanovsk Region ◽  
Pure Cultures ◽  
Short Time

The causative agent of furunculosis Aeromonas salmonicida is widely spread around the world and usually affects many cold-water fish (trout), salmon, and less often fish from other families. Currently, there is no scheme for indicating the bacterium of the species A. salmonicida from objects of the external environment, using bacteriophages and accumulation media, which complicates the study of the distribution area of the mentioned microorganism and rapid indication of the pathogen. For this reason, the aim of the study was to develop a scheme for the indication of A. salmonicida bacteria using bacteriophages. To identify field strains of A. salmonicida, we examined 56 samples of water objects in Ulyanovsk and the Ulyanovsk region. Using the environment of accumulation of A. Sl.1 and the differential diagnostic environment A.Sl.2.7 A. salmonicida strains were isolated and typed from 56 samples. We have developed a scheme for the indication of A. salmonicida bacteria based on the modification of the phage titer increase reaction (RSF) using the accumulation medium A.Sl.1. This scheme allows detecting A. salmonicida in the amount of 103m.K./ml within 24 hours. The proposed scheme has the potential to be modified and applied to a whole range of microorganisms, sensitive and specific, allowing to detect bacteria in the substrate in a short time, in the presence of foreign microflora without isolation of pure cultures.

Cell cycle arrest and astrocytic differentiation resulting from PTEN expression in glioma cells

1999 ◽  
Vol 91 (5) ◽  
pp. 822-830 ◽  
Author(s):  
Jun-ichi Adachi ◽  
Katsumi Ohbayashi ◽  
Tomonari Suzuki ◽  
Tomio Sasaki
Keyword(s):  
Expression System ◽  
Biological Significance ◽  
Glioma Cells ◽  
Genetic Alterations ◽  
Pten Expression ◽  
Human Glioma ◽  
Wild Type ◽  
Content Type ◽  
Astrocytic Differentiation ◽  
Fine Print

Object. Genetic alterations of the PTEN gene (also known as MMAC1 or TEP1) have frequently been identified in high-grade gliomas, indicating that inactivation of PTEN plays a crucial role in human glioma progression. The aim of this study was to assess the biological significance of PTEN inactivation in the development of glioma.Methods. The authors introduced wild-type PTEN complementary DNA into four human glioma cell lines (T98G, U-251MG, U-87MG, and A172) containing endogenous aberrant PTEN alleles. The number of colonies transfected with the wild-type PTEN was reduced to 15 to 32% of those found after transfection of a control vector, suggesting growth suppression by the exogenous PTEN. To analyze phenotypic alterations produced by PTEN expression, T98G-derived clones with inducible PTEN expression were further established using a tetracycline-regulated inducible gene expression system. Induction of PTEN expression suppressed the in vitro growth of T98G cells with accumulation of G1 phase cells. Furthermore, when cells were cultured in the presence of the extracellular matrix (ECM), PTEN expression caused distinct morphological changes, with multiple and elongated cytoplasmic processes similar to those of normal astrocytes. The level of glial fibrillary acidic protein, an intermediate protein specifically expressed in differentiated astrocytes, was upregulated concomitantly.Conclusions. These findings strongly indicate that exogenous PTEN expression inhibits the proliferation of glioma cells by inducing G1 arrest and elicits astrocytic differentiation in the presence of the ECM. Inactivation of PTEN would play an important role in the enhancement of unregulated growth of undifferentiated glioma cells.

scholarly journals Microencapsulation of oil droplets using cold water fish gelatine/gum arabic complex coacervation by membrane emulsification

2013 ◽  
Vol 53 (1) ◽  
pp. 362-372 ◽  
Author(s):  
Emma Piacentini ◽  
Lidietta Giorno ◽  
Marijana M. Dragosavac ◽  
Goran T. Vladisavljević ◽  
Richard G. Holdich
Keyword(s):  
Cold Water ◽  
Gum Arabic ◽  
Complex Coacervation ◽  
Oil Droplets ◽  
Membrane Emulsification ◽  
Water Fish

MAGNETIC BEHAVIOUR OF UPdAl, UCuGa AND UCuSn

1993 ◽  
Vol 07 (01n03) ◽  
pp. 850-854 ◽  
Author(s):  
V.H. TRAN ◽  
R. TROĆ
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Low Temperatures ◽  
Magnetic Behaviour ◽  
Type Structure ◽  
Complex Structures ◽  
Temperature Dependent ◽  
Antiferromagnetic Ordering

Magnetic susceptibility and electrical resistivity have been measured on UCuGa, UCu1+xSn1−x, (x=0 and 0.1), and UPdAl. The first two compounds, crystallizing in the hexagonal CaIn2-type structure, show at low temperatures an antiferromagnetic ordering probably with complex structures. UPdAl, which adopts the orthorhombic TiNiSi-type structure, was found to be a weakly temperature-dependent paramagnet down to 4.2 K.

scholarly journals Untangling mechanisms of crude oil toxicity: Linking gene expression, morphology and PAHs at two developmental stages in a cold-water fish

2021 ◽  
Vol 757 ◽  
pp. 143896
Author(s):  
Elin Sørhus ◽  
Carey E. Donald ◽  
Denis da Silva ◽  
Anders Thorsen ◽  
Ørjan Karlsen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Crude Oil ◽  
Developmental Stages ◽  
Cold Water ◽  
Water Fish ◽  
Oil Toxicity

Laser pulses and rotation effects with the temperature-dependent properties in micropolar thermoelastic solids with microtemperatures

2019 ◽  
Vol 15 (2) ◽  
pp. 418-436 ◽  
Author(s):  
Mohamed I.A. Othman ◽  
Ramadan S. Tantawi ◽  
Mohamed I.M. Hilal
Keyword(s):  
Earthquake Engineering ◽  
Human Body ◽  
Design Methodology ◽  
Laser Pulses ◽  
Temperature Dependent ◽  
Thermoelastic Medium ◽  
Content Type ◽  
Thermoelastic Solid ◽  
Temperature Dependent Properties ◽  
Physical Quantities

PurposeThe purpose of this paper is to report effect of rotation of micropolar thermoelastic solid with microtemperatures heated by laser pulses. The problem was solved analytically to obtain the expressions of the physical quantities.Design/methodology/approachThe analytical method used was the normal mode.FindingsNumerical results for the physical quantities were presented graphically and the results were analyzed. The comparisons were established in variant cases of the effects used and then shown graphically.Originality/valueIn the present work, the authors shall discuss the effect of rotation and temperature-dependent properties with the laser pulses in the micropolar thermoelastic medium with microtemperatures. This problem is very important in more empirical branches such as the human body and earthquake engineering.

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