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Calculation of the new climatological standard normals for the period 1991–2020 was a motivation to carry out the homogenization of the required climatic variables in the Spanish Meteorological Agency (AEMET). The national observation network has undergone changes along its history that often introduce non-climatic interferences to the series. On the other hand, for the calculation of various parameters and climatic indices, it is essential to have complete daily series. With this in mind, homogenization of daily series of precipitation, maximum and minimum temperatures, sunshine hours, relative humidity, station level pressure, mean wind speed, and maximum wind gust was carried out. This paper shows how the homogenization process was performed, covering the period 1975–2020 with carefully selected daily data sets from the national climatological database. The homogenization software Climatol v.4.0 was used for this process, and derived variables such as average temperature, sea level pressure, and vapor pressure were calculated from their related homogenized series. The peculiarities and issues of each variable are explored and, finally, the homogenization results were used to readily calculate the 1991–2020 climatological standard normals with the dedicated software CLINO_tool v.1.5. [ABSTRACT FROM AUTHOR]

Among pollution remediation technologies, advanced oxidation processes (AOPs) are genuinely efficient since they are based on the production of strong, non-selective oxidants, mainly hydroxyl radicals (·OH), by a set of physicochemical methods. The biological counterparts of AOPs, which may be referred to as advanced bio-oxidation processes (ABOPs), have begun to be investigated since the mechanisms of induction of ·OH production in fungi are known. To contribute to the development of ABOPs, advanced oxidation of a wide number of dyes by the white-rot fungus Pleurotus eryngii, via a quinone redox cycling (QRC) process based on Fenton's reagent formation, has been described for the first time. The fungus was incubated with 2,6-dimethoxy-1,4-benzoquinone (DBQ) and Fe3+-oxalate, with and without Mn2+, leading to different ·OH production rates, around twice higher with Mn2+. Thanks to this process, the degradative capacity of the fungus increased, not only oxidising dyes it was not otherwise able to, but also increasing the decolorization rate of 20 dyes by more than 7 times in Mn2+ incubations. In terms of process efficacy, it is noteworthy that with Mn2+ the degradation of the dyes reached values of 90–100% in 2–4 h, which are like those described in some AOPs based on the Fenton reaction. [ABSTRACT FROM AUTHOR]

Measurements in seven sites in the Campus of the University of the Balearic Islands (UIB; Mallorca, Spain) during an experimental campaign to study the contribution of local surface heterogeneities on the surface energy budget at one point have been used to characterize the differences in extreme daily temperatures between the sites during a summer month. Absolute temperature differences in this month reached up to 1.92 (with a median of 0.73) and 2.02 (median of 1.21)°C for daily maximum and minimum, respectively. Higher differences in the minimum temperature can be attributed to the stably stratified and weak turbulent conditions at night that enhance local differences in the surface energy fluxes, especially in an area with strong variability of the surface characteristics like the UIB Campus. Instead, during daytime, maximum temperature differences are smoothed due to the convection and the horizontal advection due to the sea‐breeze. Two sites with longer records allowed to study the seasonal variations of these differences, which were substantially lower in the colder months. These results suggest that relocation of observatories, even at distances as short as 200 m, may introduce important inhomogeneities in the temperature series. Therefore, raw values of series from nearby stations should not be used to infill missing data in other series without adequate statistical adjustments. [ABSTRACT FROM AUTHOR]

The homogenization of climate observational series is a needed process before undertaking confidently any study of their internal variability, since changes in the observation methods or in the surroundings of the observatories, for instance, can introduce biases in the data of the same order of magnitude than the underlying climate variations and trends. Many methods have been proposed in the past to remove the unwanted perturbations from the climatic series, and some of them have been implemented in software packages freely available on the Internet. The Spanish project MULTITEST was intended to test their performance in an automatic way with synthetic monthly series of air temperature and atmospheric precipitation, to update inter‐comparison results from former projects, especially those of the COST Action ES0601. Several networks representing different climates and station densities were used to test a variety of homogenization packages on hundreds of random samples. Results were evaluated mainly in the form of root mean squared errors and errors in the trend of the series, showing that ACMANT, followed by Climatol, minimized these errors. However, other packages performed also relatively well, even outperforming them when there were simultaneous biases of the same sign in most or all the test series. [ABSTRACT FROM AUTHOR]

Using observations and model simulations from the 5th and 6th phases of the Coupled Model Intercomparison Project (CMIP5 and CMIP6, respectively), this study evaluated changes in monthly, seasonal, and annual precipitation over Bolivia from 1950 to 2019. Results demonstrate that observed precipitation is characterized by strong interannual and decadal variability. However, long‐term precipitation trends were not identified on the annual scale. Similarly, changes in seasonal precipitation were almost nonsignificant (p >.05) for the study period. Spatially, albeit with its complex orography, no substantial regional variations in observed precipitation trends can be identified across Bolivia. In contrast, long‐term precipitation trends, based on CMIP5 and CMIP6 models, suggest a dominance of negative trends, mainly during austral winter (JJA) (−10%) and spring (SON) (−15%). These negative trends were more pronounced in the lowlands of Bolivia (−20%). Overall, these contradictory results highlight the need for validating precipitation trend outputs from model simulations, especially in areas of complex topography like Bolivia. [ABSTRACT FROM AUTHOR]

Byline: Martín. Hove, Jorge. Gil, Teresa. Rodríguez, Ángel. Lomas, Jesús. Casajús, Antonio. López-Farré, José. Guijarro Retrorectal cystic hamartomas, or tailgut cysts, are complex congenital cystic lesions which arise from embryologic [...]

Introduction: Essential tremor (ET) is one of the most prevalent movement disorders in adults and may be highly disabling for some. Magnetic resonance image-guided high-intensity focused ultrasound (MRIgFUS) has been shown to control tremor efficaciously and with acceptable risk. To date, paresthesia and ataxia are the most common adverse effects (AE). Nevertheless, the impact of MRIgFUS thalamotomy on balance is not well established. Methods: Thirty-two patients underwent MRIgFUS for ET and completed 6 months of follow-up. Tremor severity and functional disability were assessed using the Essential Tremor Rating Scale and the Quality of Life in Essential Tremor Questionnaire. The Berg Balance Scale (BBS) was applied to objectively measure balance status. Results: All treatments were successful. The sonication target was 1–2 mm above the depth of the intercommissural line. Procedures lasted less the 2 h, with an average of 8 sonications per patient. Twenty-four patients were included in the tremor analysis. The hand tremor score was improved by 76% after 6 months of follow-up and 87% of patients self-reported marked improvement (≥75%). Disability scores showed marked improvement (78%), leading to a significant improvement in quality of life. At the final follow-up, 48% of the patients reported no side effects. When present, AE were generally transient and were considered mild in 96% of affected patients. Paresthesia and subjective feeling of unsteadiness were the most common persistent complaints (23% and 20%, respectively). Regarding objective ataxia, BBS scores remained stable throughout follow-up for most patients. Only 2 patients suffered a mild worsening of balance although no patients experienced moderate or severe ataxia. Conclusions: Subjective feeling of unsteadiness is one of the most frequent AE after MRIgFUS, although objective ataxia is infrequent and mild. Selecting the most appropriate lesion location and procedural parameters should increase treatment benefits while reducing side effects. [ABSTRACT FROM AUTHOR]

A dense monthly precipitation dataset of Ireland and Northern Ireland was homogenized with several modern homogenization methods. The efficiency of these homogenizations was tested by examining the similarity of homogenization results both in the real data homogenization and in the homogenization of a simulated dataset. The analysis of homogenization results shows that the real dataset is characterized by a large number of, but mostly small, non‐climatic biases, and a moderate reduction of such biases can be achieved with homogenization. Finally, a combination of the ACMANT and Climatol homogenization results was applied to improve the data accuracy before the trend calculations. These two methods were selected for their proven high accuracy, missing data tolerance and ability to complete time series via the infilling of missing values before the trend calculations. Metadata were used within the Climatol method. To facilitate this analysis the study area was split into smaller climatic regions by using the Ward clustering method. Five climatic zones consistent with the known spatial patterns of precipitation in Ireland were established. Linear regression fitting and the Mann‐Kendall test were applied. Low frequency fluctuations were also examined by applying a Gaussian filter. The results show that the precipitation amount generally increases in the study area, particularly in the northwestern region. The most significant increasing trends for the whole study period (1941–2010) are found for late winter and spring precipitation, as well as for the annual totals. In the period from the early 1970s the increase of precipitation is general in all seasons of the year except in winter, but the statistical significance of this increase is weak. [ABSTRACT FROM AUTHOR]

Time series homogenization for 299 of the available precipitation records for the island of Ireland (IENet) was performed. Four modern relative homogenization methods, that is, HOMER, ACMANT, CLIMATOL and AHOPS were applied to this network of station series where contiguous intact monthly records range from 30 to 70 years within the base period 1941–2010. Break detection results are compared between homogenization methods, and coincidences with available documentary information (metadata) were analysed. The lowest (highest) number of breaks were detected with HOMER (ACMANT). Large differences of break frequency were found, namely ACMANT and AHOPS detected 8 times as many breaks than HOMER, while the break frequency with CLIMATOL was intermediate. Also, the ratio of series classified to be homogeneous varies widely between the methods. It is 85% with HOMER, 60% with CLIMATOL, 31% with AHOPS, while only 22% with ACMANT. In a further experiment, all the available time series for Ireland and Northern Ireland, (910 series) were used with ACMANT and CLIMATOL to explore the stability of break frequency for the same 299 series examined in the base experiment. While overall break frequency slightly increased (by 6–13%), the break positions notably changed for individual time series. The number of breaks changed for 59% (23%) of the series with ACMANT (CLIMATOL). For the breaks detected coincidentally by at least three methods including ACMANT and CLIMATOL in the base experiment, the second experiment confirmed the break positions in 86–87% of the breaks. The consequences of these results in relation to the reliability of statistical homogenization are discussed. Sometimes markedly different step functions provide comparable good approaches. However, the accuracy of homogenized time series cannot be related directly to the instability of break detection results. [ABSTRACT FROM AUTHOR]

Daily and sub‐daily homogenization of climate variables have been intensively investigated in the last decades, but to the best of our knowledge, this is the first study on homogenization of hourly temperature in Romania. This paper describes the creation of a homogenized hourly air temperature data set at a country scale by combining data from four independent meteorological networks. The air temperature measurements for the period 2009 and 2017 were obtained from the following networks: Romanian National Meteorological Administration (ANM), National Network for Monitoring Air Quality (RNMCA), Regional Basic Synoptic Network (RBSN), and Meteorological Terminal Aviation Routine Weather Report network (METAR). The climatological limits, persistence, temporal variation (step test), and spatial consistency were the quality control tests used to isolate the errors due to malfunctioning of the temperature sensors, data coding or transmission. The Climatol homogenization method was successfully applied for identifying and correcting any suspicious values. The missing data were filled by considering the similarities between each station and the reference series. Comparing the output with the original data, it is apparent that the removal of the break points, correction and homogenization resulted in a new data set with statistical properties very similar to the raw data, but more reliable for climate research due to the increased homogeneity. Eventually, the procedure can be implemented in operational use for collecting more data from other networks. [ABSTRACT FROM AUTHOR]

Bacterial antibiotic resistance is one of the main healthcare problems currently. Apart from reducing antibiotic efficacy, it has awakened the interest of scientists due to its association with bacterial fitness and virulence. Interestingly, antibiotic resistance can be a source of both increased fitness and decreased fitness, even though the molecular basis of these relationships remains unknown. The aim of this work is to define the effects of sub‐MIC concentrations of cefotaxime, an antibiotic extensively used in clinical practice, on the physiology and virulence of Yersinia ruckeri and to determine the importance of these sub‐MIC concentrations for the selection of antibiotic‐resistant mutants in the aquatic environment. Results indicated that exposure to sub‐MIC concentrations of cefotaxime selected Y. ruckeri populations with irreversible alterations in the physiology, such as slow growth, aggregation in liquid cultures and modification of the colony morphology. These bacteria also displayed changes in the OMPs and LPS profiles and a full attenuation of virulence. An overexpression of the envelope stress regulator RpoE was also detected after exposure to the antibiotic. In conclusion, exposure to cefotaxime selected, at high frequency, Y. ruckeri strains that survive the antibiotic stress at the expense of a fitness cost and the loss of virulence. [ABSTRACT FROM AUTHOR]

A new high‐resolution (5 km) gridded daily precipitation dataset for Tunisia between 1979 and 2015 is introduced. This product combines 960 rain gauges with the SAFRAN analysis to produce the precipitation gridded data. A validation approach on two different datasets reveals that the SAFRAN analysis outperforms other standard interpolation methods such as Inverse Distance, Nearest Neighbors, Ordinary Kriging or Residual Kriging with altitude. When compared to EOBS, a widely used gridded dataset over Europe, a strong negative bias in EOBS precipitation is found. However due to the aridity and the low density of rain gauges in south Tunisia, results in this region must be analyzed with care. The SAFRAN product could be useful for various purposes such as climate model evaluation, climate studies, hydrological modelling to support the planning and management of surface water resources in Tunisia. [ABSTRACT FROM AUTHOR]

Finding the keys to understanding the infectious process of Yersinia ruckeri was not a priority for many years due to the prompt development of an effective biotype 1 vaccine which was used mainly in Europe and USA. However, the gradual emergence of outbreaks in vaccinated fish, which have been reported since 2003, has awakened interest in the mechanism of virulence in this pathogen. Thus, during the last two decades, a large number of studies have considerably enriched our knowledge of many aspects of the pathogen and its interaction with the host. By means of both conventional and a variety of novel strategies, such as cell GFP tagging, bioluminescence imaging and optical projection tomography, it has been possible to determine three putative Y. ruckeri infection routes, the main point of entry for the bacterium being the gill lamellae. Moreover, a wide range of potential virulence factors have been highlighted by specific gene mutagenesis strategies or genome-wide transposon/plasmid insertion-based screening approaches, such us in vivo expression technology (IVET) and signature tagged mutagenesis (STM). Finally, recent proteomic and whole genomic analyses have allowed many of the genes and systems that are potentially implicated in the organism's pathogenicity and its adaptation to the host environmental conditions to be elucidated. Altogether, these studies contribute to a better understanding of the infectious process of Y. ruckeri in fish, which is crucial for the development of more effective strategies for preventing or treating enteric redmouth disease (ERM). [ABSTRACT FROM AUTHOR]

This work presents a catalog of daily precipitation fields in the Balearic Islands created with data from AEMET (State Meteorological Agency) assistant observations, including records from 1912. The original digital daily data file has been interpolated onto a regular 100 m-resolution grid (namely PREGRIDBAL), defined with the aim of becoming a valid standard for future methodological improvements and catalog upgrades. Daily precipitation amounts on each grid point are calculated using an analysis method based on ordinary kriging, using the daily anomaly with respect to the annual mean for all available observations each day. Due to quality concerns, the time span for products derived from the catalog is limited to the 1950-2009 period, when the number of operating stations reached 200. Therefore, from the time series of daily maps, monthly-, annual-, quinquennial-, and decadal-accumulations are produced. Similarly, the catalog allowed for quantification of climate trends in rainfall amounts in the Balearic Islands, with the significant advantage of minimizing the biases originated from heterogeneities in the spatial distribution of stations across the archipelago. Results show a general decrease in precipitation during the 1950-2009 period. From 1950 to 1979, the average annual precipitation across the islands was 624.3 mm, while from 1980 to 2009 it diminished to 555.36 mm. Changes in precipitation patterns, which vary among the different areas, are also detected. The most significant reductions are found in the northern half of the archipelago and especially in Mallorca, where the Tramuntana mountain range stands out. All seasonal trends show a decrease, with values ranging between 1 and 3 mm decade-1, with the exception of autumn, which reaches a positive trend up to 7 mm decade-1. October shows the most dramatic decrease (-10:34 mm decade-1) and, conversely, September and November show an increase in precipitation (3.28 and 1.82 mm decade-1, respectively) with a statistical significance above 85% across almost the entire archipelago, and even exceeding 95% in Eivissa and Formentera. [ABSTRACT FROM AUTHOR]

Background: 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) lyase deficiency is a rare inborn error of metabolism characterized by recurrent metabolic crises caused by fasting, intercurrent illness and excessive physical exercise. Non ketotic hypoglycemia is normally the cause of primary symptoms but without an immediate treatment the illness can evolve into a worsening metabolic state resembling the Reye's syndrome that may cause the patient's death. We report a case with some clinical and therapeutic features not previously described. Case presentation: Patient with HMG-CoA lyase deficiency whom after diagnosis at 2 years of age was re- admitted 12 years later, after severe metabolic decompensation following consumption of alcohol. Despite a quick correction of hypoglycemia, within the following few hours, the patient fell into a coma. Suspecting intracranial hypertension (ICH), the patient required mechanical ventilation. Although liver cytolysis was minimal, hyperamoniemia reached 1394 µmol/L, returning to normal, a few hours after administering sodium phenylacetate and sodium benzoate, whose use has not been reported in these patients. Brain edema was evidenced in the computed tomography and by the magnetic resonance imaging that determined that the edema was cytotoxic, as quantified with the restriction of diffusion in the apparent diffusion coefficient map. During the recovery of the ICH, we belatedly, detected vasospasm moderate-severe that was treated with nimodipine. Currently, the patient maintains clinical normality. Conclusions: The alcohol consumption must be avoided in patients with HMG-CoA lyase deficiency. In our patient hyperamoniemia was effectively treated with sodium phenylacetate and sodium benzoate. Magnetic resonance imaging showed and quantified the cytotoxic brain edema. Belatedly, a cerebral vasospasm was an additional mechanism of cerebral injury. None of these observations has been previously reported. [ABSTRACT FROM AUTHOR]

Retroperitoneal cystic mesothelioma is a very rare lesion. The pathogeny is unclear and establishing a preoperative diagnosis versus others retroperitoneal cystic lesions is difficult. Thus, with increasing experience in laparoscopic retroperitoneal surgery, the use of this approach for exploration of a retroperitoneal mass of unknown origin may provide an alternative to classic open surgery and all the benefits of laparoscopy. We present two cases treated laparoscopycally and review the literature. [ABSTRACT FROM AUTHOR]

This work presents a catalog of daily precipitation in the Balearic Islands created with data from AEMET assistant observers, including registers since 1912. The original digital daily data file has been interpolated onto a regular 100m resolution grid (namely PREGRIDBAL), defined with the aim of becoming a valid standard for future methodological improvements and catalog upgrades. Daily precipitation amounts on each grid-point are calculated using an analysis method based on ordinary Kriging, using the daily anomaly with respect to the annual mean for all available observations each day. Due to quality concerns, the time span for products derived from the catalogue is limited to the 1950-2009 period. Therefore, from the elementary daily maps, monthly-, annual-, quinquennial-, and decadal-accumulations are produced. Similarly, the catalog allowed for quantification of climate trends in rainfall amounts in the Balearic Islands, with the significant advantage of minimising the biases originated from heterogeneities in the spatial distribution of stations across the archipelago. Results show a general decrease in precipitation during the 1950-2009 period. From 1950 to 1979, the average annual precipitation across the islands was 624,3mm, while from 1980 to 2009 diminished to 555,36mm. Changes in precipitation patterns, which vary among the different areas, are also detected. Most significant reductions (over 80% significance on the trend) are found in the north half of the archipelago and especially in Mallorca, where the Tramuntana mountain range stands out. All seasonal trends show a decrease, with values ranging between 1 and 3mm per decade, with the exception of autumn, which reaches up to 7mm per decade. October shows the most dramatic decrease (-10,34mm per decade) and, conversely, September and November show an increase in precipitation (3,28 and 1,82mm per decade, respectively) with a statistical significance above 85% in almost all the archipelago, and even exceeding 95% in the Pitiüses. [ABSTRACT FROM AUTHOR]

Plasma membrane integrity is essential for cell life. Any major break on it immediately induces the death of the affected cell. Different molecules were described as disrupting this cell structure and thus showing antitumor activity. We have previously defined that elisidepsin (Irvalec®, PM02734) inserts and self-organizes in the plasma membrane of tumor cells, inducing a rapid loss of membrane integrity, cell permeabilization and necrotic death. Here we show that, in sensitive HCT-116 colorectal cells, all these effects are consequence of the interaction of elisidepsin with glycosylceramides in the cell membrane. Of note, an elisidepsin-resistant subline (HCT-116-Irv) presented reduced levels of glycosylceramides and no accumulation of elisidepsin in the plasma membrane. Consequently, drug treatment did not induce the characteristic necrotic cell death. Furthermore, GM95, a mutant derivative from B16 mouse melanoma cells lacking ceramide glucosyltransferase (UGCG) activity and thus the synthesis of glycosylceramides, was also resistant to elisidepsin. Over-expression of UGCG gene in these deficient cells restored glycosylceramides synthesis, rendering them sensitive to elisidepsin, at a similar level than parental B16 cells. These results indicate that glycosylceramides act as membrane targets of elisidepsin, facilitating its insertion in the plasma membrane and the subsequent membrane permeabilization that leads to drug-induced cell death. They also indicate that cell membrane lipids are a plausible target for antineoplastic therapy. [ABSTRACT FROM AUTHOR]

Virulence gene expression in pathogenic bacteria is modulated by environmental parameters. A key factor in this expression is temperature. Its effect on virulence gene expression in bacteria infecting warm-blooded hosts is well documented. Transcription of virulence genes in these bacteria is induced upon a shift from low environmental to a higher host temperature (37◦C). Interestingly, host temperatures usually correspond to the optimum for growth of these pathogenic bacteria. On the contrary, in ectothermic hosts such as fish, molluscs, and amphibians, infection processes generally occur at a temperature lower than that for the optimal growth of the bacteria. Therefore, regulation of virulence gene expression in response to temperature shift has to be modulated in a different way to that which is found in bacteria infecting warm-blooded hosts. The current understanding of virulence gene expression and its regulation in response to temperature in fish-pathogenic bacteria is limited, but constant extension of our knowledge base is essential to enable a rational approach to the problem of the bacterial fish diseases affecting the aquaculture industry. This is an interesting issue and progress needs to be made in order to diminish the economic losses caused by these diseases. The intention of this review is, for the first time, to compile the scattered results existing in the field in order to lay the groundwork for future research. This article is an overview of those relevant virulence genes that are expressed at temperatures lower than that for optimal bacterial growth in different fish-pathogenic bacteria as well as the principal mechanisms that could be involved in their regulation. [ABSTRACT FROM AUTHOR]

Flavobacterium psychrophilum is a Gram-negative fish pathogen that causes important economic losses in aquaculture worldwide. Although the genome of this bacterium has been determined, the function and relative importance of genes in relation to virulence remain to be established. To investigate their respective contribution to the bacterial pathogenesis, effective tools for gene inactivation are required. In the present study, a markerless gene deletion system has been successfully developed for the first time in this bacterium. Using this method, the F. psychrophilum fcpB gene, encoding a predicted cysteine protease homologous to Streptococcus pyogenes streptopain, was deleted. The developed system involved the construction of a conjugative plasmid that harbors the flanking sequences of the fcpB gene and an I-SceI meganuclease restriction site. Once this plasmid was integrated in the genome by homologous recombination, the merodiploid was resolved by the introduction of a plasmid expressing I-SceI under the control of the fpp2 F. psychrophilum inducible promoter. The resulting deleted fcpB mutant presented a decrease in extracellular proteolytic activity compared to the parental strain. However, there were not significant differences between their LD50 in an intramuscularly challenged rainbow trout infection model. The mutagenesis approach developed in this work represents an improvement over the gene inactivation tools existing hitherto for this “fastidious” bacterium. Unlike transposon mutagenesis and gene disruption, gene markerless deletion has less potential for polar effects and allows the mutation of virtually any non-essential gene or gene clusters. [ABSTRACT FROM AUTHOR]

Flavobacterium psychrophilum is an important fish pathogen, responsible for Cold Water Disease, with a significant economic impact on salmonid farms worldwide. In spite of this, little is known about the bacterial physiology and pathogenesis mechanisms, maybe because it is difficult to manipulate, being considered a fastidious microorganism. Mutants obtained using a Tn4351 transposon were screened in order to identify those with alteration in colony morphology, colony spreading and extracellular proteolytic activity, amongst other phenotypes. A F. psychrophilum mutant lacking gliding motility showed interruption of the FP1638 locus that encodes a putative type-2 glycosyltransferase (from here on referred to as fpgA gene, Flavobacterium psychrophilum glycosyltransferase). Additionally, the mutant also showed a decrease in the extracellular proteolytic activity as a consequence of down regulation in the fpgA mutant background of the fpp2-fpp1 operon promoter, responsible for the major extracellular proteolytic activity of the bacterium. The protein glycosylation profile of the parental strain showed the presence of a 22 kDa glycosylated protein which is lost in the mutant. Complementation with the fpgA gene led to the recovery of the wild-type phenotype. LD50 experiments in the rainbow trout infection model show that the mutant was highly attenuated. The pleiotropic phenotype of the mutant demonstrated the importance of this glycosyltranferase in the physiology and virulence of the bacterium. Moreover, the fpgA mutant strain could be considered a good candidate for the design of an attenuated vaccine. [ABSTRACT FROM AUTHOR]

Background The heat sensitive factor (HSF) of the fish pathogen Yersinia ruckeri was previously identified as an unusual band on SDS-PAGE. According to this, Y. ruckeri strains were classified in HSF+ and HSF- in terms of the presence/absence of the factor. Experiments carried out by injection challenge with HSF+ strains caused high mortalities in rainbow trout. In contrast, HSF- strains did not cause mortality. In conclusion, HSF appeared to be a relevant virulence factor in Y. ruckeri. Results We report here the identification and study of the gene coding for the enzyme involved in the production of HSF. Culture media containing SDS and Coomassie brilliant blue dye was used to screen a mini-Tn5 Km2 mutant library of Y. ruckeri 150. Blue colonies lacking a surrounding creamy deposit, a phenotype described in former studies as HSF-, were identified. DNA sequence analysis of a selected mutant revealed that this had a transposon interruption in a chromosome-located gene which codes for a heat sensitive alkyl sulphatase of 78.7 kDa (YraS; Yersinia ruckeri alkyl sulphatase) which is able to degrade SDS to 1- dodecanol. As it was expected, the introduction of the yraS gene into an HSF- strain turned this into HSF+. Surprisingly, although the protein allows Y. ruckeri to degrade SDS, the bacterium could not use this compound as the sole carbon source. Moreover, the yraS mutant showed a similar level of SDS resistance to the parental strain. It was the interruption of the acrA gene which made Y. ruckeri sensitive to this compound. LD50 experiments showed a similar virulence of the yraS mutant and parental strain. Conclusions The HSF of Y. ruckeri is the product of the alkyl sulphatase YraS, able to degrade SDS to 1- dodecanol. This degradation is not linked to the utilization of SDS as a carbon source and surprisingly, the enzyme is not involved in bacterial virulence or in the high SDS resistance displayed by the bacterium. This role is played by the AcrAB-TolC system. [ABSTRACT FROM AUTHOR]

Bacterial cold water disease ( BCWD) is a globally distributed freshwater fish disease caused by the Gram-negative bacterium F lavobacterium psychrophilum. It is a particularly devastating infection in fry salmonids and may lead to high levels of mortality. In spite of its economic impact on fish farms, neither the biology of the bacterium nor the bacterium-host interactions are well understood. This review provides a synopsis of the major problems related to critical remaining questions about research into the use of vaccines against F. psychrophilum and the development of a commercial vaccine against this disease. Studies using sera from convalescent rainbow trout have shown the antigenic properties of different proteins such as OmpH, OmpA and FspA, as well as low and high molecular mass lipopolysaccharide of F . psychrophilum, which are potential candidates for subunit vaccines. Inactivated F . psychrophilum bacterins have been successfully tested as vaccines under laboratory conditions by both immersion and intraperitoneal routes. However, the efficacy and the practical usefulness of these preparations still have to be proved. The use of attenuated and wild-type strains to immunize fish showed that these systems offer high levels of protection. Nevertheless, their application clashes with the regulations for environmental protection in many countries. In conclusion, protective vaccines against BCWD are theoretically possible, but substantial efforts still have to be made in order to permit the development of a commercial vaccine. [ABSTRACT FROM AUTHOR]