Digenean trematodes of Seriolella porosa (Pisces, Centrolophidae) in San Matías Gulf, Argentina

Seriolella porosa (Silver warehou) is an important fish resource in the Argentine Sea. No previous studies have been carried out to date on its parasite fauna. The present study aims to (i) identify the digenean trematodes that parasitize Silver warehou, (ii) estimate parasite frequency and abundance, and (iii) establish their relationship with fish size and sex. A total of 100 specimens of S. porosa from San Matías Gulf, Argentina were examined between September and October 2006. Host size and sex were determined. Parasites extracted from the stomach lumen were fixed, conserved in 5% formalin, and stained with Langeron's hydrochloric carmine. The following parameters were also determined: dispersion coefficient, prevalence, intensity, and parasite abundance. Differences in parasitism were assessed using non-parametric tests. Four adult digenean species were found in the stomach, namely Lecithocladium cristatum, Aponurus laguncula, Elytrophalloides oatesi and Gonocerca cf. phycidis. L. cristatum was not only dominant but also the most prevalent and abundant species. None of the digeneans showed interspecific association with each other and therefore they might follow different patterns of colonization (i. e., different intermediate hosts, seasonal and/or spatial distribution of the infective stages). Significant differences were observed among the digeneans analyzed in respect to the sex of the host. Results from this study show that Silver warehou plays a key role as a final host of a significant number of digeneans in the ecosystem. This study is the first step in an attempt to further determine the larval stages in intermediate hosts in San Matías Gulf.Centro de Estudios Parasitológicos y de Vectore

Digenean trematodes of Seriolella porosa (Pisces, Centrolophidae) in San Matías Gulf, Argentina

Seriolella porosa (Silver warehou) is an important fish resource in the Argentine Sea. No previous studies have been carried out to date on its parasite fauna. The present study aims to (i) identify the digenean trematodes that parasitize Silver warehou, (ii) estimate parasite frequency and abundance, and (iii) establish their relationship with fish size and sex. A total of 100 specimens of S. porosa from San Matías Gulf, Argentina were examined between September and October 2006. Host size and sex were determined. Parasites extracted from the stomach lumen were fixed, conserved in 5% formalin, and stained with Langeron's hydrochloric carmine. The following parameters were also determined: dispersion coefficient, prevalence, intensity, and parasite abundance. Differences in parasitism were assessed using non-parametric tests. Four adult digenean species were found in the stomach, namely Lecithocladium cristatum, Aponurus laguncula, Elytrophalloides oatesi and Gonocerca cf. phycidis. L. cristatum was not only dominant but also the most prevalent and abundant species. None of the digeneans showed interspecific association with each other and therefore they might follow different patterns of colonization (i. e., different intermediate hosts, seasonal and/or spatial distribution of the infective stages). Significant differences were observed among the digeneans analyzed in respect to the sex of the host. Results from this study show that Silver warehou plays a key role as a final host of a significant number of digeneans in the ecosystem. This study is the first step in an attempt to further determine the larval stages in intermediate hosts in San Matías Gulf.Centro de Estudios Parasitológicos y de Vectore

Altered expression of genes implicated in xylan biosynthesis affects penetration resistance against powdery mildew

Heteroxylan has recently been identified as an important component of papillae, which are formed during powdery mildew infection of barley leaves. Deposition of heteroxylan near the sites of attempted fungal penetration in the epidermal cell wall is believed to enhance the physical resistance to the fungal penetration peg and hence to improve pre-invasion resistance. Several glycosyltransferase (GT) families are implicated in the assembly of heteroxylan in the plant cell wall, and are likely to work together in a multi-enzyme complex. Members of key GT families reported to be involved in heteroxylan biosynthesis are up-regulated in the epidermal layer of barley leaves during powdery mildew infection. Modulation of their expression leads to altered susceptibility levels, suggesting that these genes are important for penetration resistance. The highest level of resistance was achieved when a GT43 gene was co-expressed with a GT47 candidate gene, both of which have been predicted to be involved in xylan backbone biosynthesis. Altering the expression level of several candidate heteroxylan synthesis genes can significantly alter disease susceptibility. This is predicted to occur through changes in the amount and structure of heteroxylan in barley papillae.Jamil Chowdhury, Stefanie Lück, Jeyaraman Rajaraman, Dimitar Douchkov, Neil J. Shirley, Julian G. Schwerdt, Patrick Schweizer, Geoffrey B. Fincher, Rachel A. Burton and Alan Littl

Case studies to enhance graduate employability: Indigenous employment and supports

This is one in a series of case studies to enhance graduate employability. This case study on the context of Indigenous employment and supports is based on interviews and focus groups with 14 people across the stakeholder groups of employed graduates, students in internships, educators,career development professionals and employers from six different universities

Digenean trematodes of Seriolella porosa (Pisces, Centrolophidae) in San Matías Gulf, Argentina

Seriolella porosa (Silver warehou) is an important fish resource in the Argentine Sea. No previous studies have been carried out to date on its parasite fauna. The present study aims to (i) identify the digenean trematodes that parasitize Silver warehou, (ii) estimate parasite frequency and abundance, and (iii) establish their relationship with fish size and sex. A total of 100 specimens of S. porosa from San Matías Gulf, Argentina were examined between September and October 2006. Host size and sex were determined. Parasites extracted from the stomach lumen were fixed, conserved in 5% formalin, and stained with Langeron's hydrochloric carmine. The following parameters were also determined: dispersion coefficient, prevalence, intensity, and parasite abundance. Differences in parasitism were assessed using non-parametric tests. Four adult digenean species were found in the stomach, namely Lecithocladium cristatum, Aponurus laguncula, Elytrophalloides oatesi and Gonocerca cf. phycidis. L. cristatum was not only dominant but also the most prevalent and abundant species. None of the digeneans showed interspecific association with each other and therefore they might follow different patterns of colonization (i. e., different intermediate hosts, seasonal and/or spatial distribution of the infective stages). Significant differences were observed among the digeneans analyzed in respect to the sex of the host. Results from this study show that Silver warehou plays a key role as a final host of a significant number of digeneans in the ecosystem. This study is the first step in an attempt to further determine the larval stages in intermediate hosts in San Matías Gulf.Centro de Estudios Parasitológicos y de Vectore

How to survey displaced workers in Switzerland ? Sources of bias and ways around them

Studying career outcomes after job loss is challenging because individually displaced worker form a self-selected group. Indeed, the same factors causing the workers to lose their jobs, such as lack of motivation, may also reduce their re-employment prospects. Using data from plant closures where all workers were displaced irrespective of their individual characteristics offers a way around this selection bias. There is no systematic data collection on workers displaced by plant closure in Switzerland. Accordingly, we conducted our own survey on 1200 manufacturing workers who had lost their job 2 years earlier. The analysis of observational data gives rise to a set of methodological challenges, in particular nonresponse bias. Our survey addressed this issue by mixing data collection modes and repeating contact attempts. In addition, we combined the survey data with data from the public unemployment register to examine the extent of nonresponse bias. Our analysis suggests that some of our adjustments helped to reduce bias. Repeated contact attempts increased the response rate, but did not reduce nonresponse bias. In contrast, using telephone interviews in addition to paper questionnaires helped to substantially improve the participation of typically underrepresented subgroups. However, the survey respondents still differ from nonrespondents in terms of age, education and occupation. Interestingly, these differences have no significant impact on the substantial conclusion about displaced workers' re-employment prospects

Another building block in the plant cell wall: Barley xyloglucan xyloglucosyl transferases link covalently xyloglucan and anionic oligosaccharides derived from pectin

Published online 16 August 2020.We report on the homo‐ and hetero‐transglycosylation activities of the HvXET3 and HvXET4 xyloglucan xyloglucosyl transferases (XET; EC 2.4.1.207) from barley (Hordeum vulgare L.), and the visualisation of these activities in young barley roots using Alexa Fluor 488‐labelled oligosaccharides. We discover that these isozymes catalyse the transglycosylation reactions with the chemically defined donor and acceptor substrates, specifically with the xyloglucan donor and the penta‐galacturonide [α(1‐4)GalAp]5 acceptor – the homogalacturonan (pectin) fragment. This activity is supported by 3D molecular models of HvXET3 and HvXET4 with the docked XXXG donor and [α(1‐4)GalAp]5 acceptor substrates at the ‐4 to +5 subsites in the active sites. Comparative sequence analyses of barley isoforms and seed‐localised TmXET6.3 from nasturtium (Tropaeolum majus L.) permitted the engineering of mutants of TmXET6.3 that could catalyse the hetero‐transglycosylation reaction with the xyloglucan/[α(1‐4)GalAp]5 substrate pair, while wild‐type TmXET6.3 lacked this activity. Expression data obtained by real‐time quantitative PCR of HvXET transcripts and a clustered heatmap of expression profiles of the gene family revealed that HvXET3 and HvXET6 co‐expressed but did not share the monophyletic origin. Conversely, HvXET3 and HvXET4 shared this relationship, when we examined the evolutionary history of 419 glycoside hydrolase 16 family members, spanning monocots, eudicots, and a basal Angiosperm. The discovered hetero‐transglycosylation activity in HvXET3 and HvXET4 with the xyloglucan/[α(1‐4)GalAp]5 substrate pair is discussed against the background of roles of xyloglucan‐pectin heteropolymers and how they may participate in spatial patterns of cell wall formation and re‐modelling, and affect the structural features of walls.Barbora Stratilová, Sergej Šesták, Jozef Mravec, Soňa Garajová, Zuzana Pakanová, Kristína Vadinová, Danica Kučerová, Stanislav Kozmon, Julian G. Schwerdt, Neil Shirley Eva Stratilová and Maria Hrmov

Apprenticeship Training in Germany – Investment or Productivity Driven?

The German dual apprenticeship system came under pressure in recent years because enterprises were not willing to offer a sufficient number of apprenticeship positions. A frequently made argument is that the gap could be closed if more firms would be willing to incur net costs during the training period. This paper investigates for the first time whether German enterprises on average indeed incur net costs during the apprenticeship period, i.e. if the impact of an increase in the share of apprentices on contemporary profits is negative. The paper uses the representative linked employer-employee panel data of the IAB (LIAB) and takes into account possible endogeneity of training intensity and unobserved heterogeneity in the profit estimation by employing panel system GMM methods. An increase in the share of apprentices has no effect on profits. This can be interpreted as a first indication that most establishments in Germany do not invest more in apprentices than their productivity effects during the apprenticeship period