Untersuchungen zum Einfluss des D-Laktatblutspiegels auf Azidose, Körperhaltung und Verhalten bei Kälbern mit Neugeborenendurchfall

Some calves with neonatal diarrhea and distinctly disturbed general condition have elevated blood levels of D-lactate and respond poorly to the usual correction of acidosis. This observation led to this prospective study with the objective to elucidate whether calves with elevated D-lactate levels require higher doses of sodium bicarbonate and more frequent treatments than calves with normal D-lactate levels. Among the calves admitted to the clinic between September, 2002, and March, 2003, 73 calves with an age of up to 3 weeks were included in this study. Further selection criteria were diarrhea (according to the history or upon admission), and metabolic acidosis with a base excess below -10 mmol/l. Exclusion criteria were hypoglycemia, hyperkalemia, evidence of myodystrophy, severe bronchopneumonia, and navel ill requiring surgical intervention. Within the period of investigation (24 hours) the calves received a standardized therapy but no anti-inflammatory drugs and no oral rehydration solutions. Dosage of sodium bicarbonate was calculated using the formula body weight x base deficit x 0.6 and administered in a volume of 2.5 liters within 3.5 hours. During the subsequent 20 hours the calves received infusions of 0.9 % sodium chloride in volumes corresponding to the estimated fluid loss. Blood samples were taken before the infusion and after four and 24 hours and assayed for D-lactate concentration and base excess; additionally, behavior and posture of the calves were recorded. Voluntary milk intake at the first regular feeding after the end of the investigation was also recorded. Approximately 85 % of the calves had elevated D-lactate levels. Significant correlations between D-lactate levels and both behavior and posture were found, allowing for a relatively reliable diagnosis of hyper-D-lactatemia on the basis of clinical signs. Posture and behavior seemed to be more strongly influenced by D-lactate than by degree of acidosis. No correlations were found between either D-lactate level or base excess, and milk intake. Mean D-lactate concentration decreased very little after the first four hours, whereas a distinct drop was observed after the subsequent 20 hours. A possible explanation for this finding is that metabolism of D-lactate increases after the normalization of blood pH. Significant correlations between D-lactate levels and base excess after the sodium bicarbonate infusion indicate that calves with elevated D-lactate levels have received to little buffer. Furthermore significant correlations between D-lactate levels and base excess after 24 hours indicate that those calves, which still had elevated D-lactate levels after this period of time, in most cases required a repeated treatment with buffer. Conclusion: Calves with clinical evidence of D-lactate acidosis require higher doses of buffer and possibly repeated treatments

Digital-Inclusive Transformation and Teacher Preparedness for Foreign Language Education – A Bilateral German-Norwegian Perspective

Digitalisation and inclusion can be understood as transversal topics in pre- and in-service teachers’ professional development. Both topics have attracted considerable research activity. However, questions of digital-inclusive transformation have only rarely been discussed within the field of foreign language teaching. Researchers in the field state a pressing need to increase digital-inclusive transformation uptake in foreign language teacher education programmes to develop a transformation ‘mindset’ in (educational) stakeholders and (future) teachers. Transformation processes in education, however, interact with preparedness for digitalisation and inclusion among pre- and in-service teachers, since the attitude and the willingness of teachers to adapt to digital reality play a decisive role in improving the quality of (digitally enhanced) teaching and learning. Currently, little is known about the interrelationship between the preparedness to use digital technology for foreign language teaching and learning and the preparedness to include foreign language learners with diverse learning needs (DLN) in the digital-inclusive classroom. To this end, this bilateral cross-country study investigates factors that constitute an attitudinal component of foreign language teachers’ perceived preparedness for using digital technology with learners with diverse learning needs in Germany and Norway. The Teacher of English Preparedness to Diverse Learning Needs in the digital inclusive classroom questionnaire was administered to 221 participants. The results show a fresh perspective on preparedness for digitally enhanced inclusive teaching linked to educational system requirements for foreign language teaching. Importantly, confidence when using digital technology in the inclusive classroom is decisive. For teacher education, it is vital that the attitudinal component of teacher preparedness receives more attention throughout teacher training. It should be related to previous experience of teachers with DT in digital-inclusive environments and be part of a heuristic conceptualisation of teacher preparedness for digitalinclusive contexts

Competition and feeding ecology in two sympatric Xenopus species (Anura: Pipidae)

CITATION: Vogt, S., et al. 2017. Competition and feeding ecology in two sympatric Xenopus species (Anura: Pipidae). PeerJ, 5:e3130, doi:10.7717/peerj.3130/table-1.The original publication is available at https://peerj.comPublication of this article was funded by the Stellenbosch University Open Access Fund.The widespread African clawed frog (Xenopus laevis) occurs in sympatry with the IUCN Endangered Cape platanna (Xenopus gilli) throughout its entire range in the south-western Cape, South Africa. In order to investigate aspects of the interspecific competition between populations of X. laevis and X. gilli, an assessment of their niche differentiation was conducted through a comprehensive study on food composition and trophic niche structure at two study sites: the Cape of Good Hope (CoGH) and Kleinmond. A total of 399 stomach contents of X. laevis (n = 183) and X. gilli (n = 216) were obtained together with samples of available prey to determine food preferences using the Electivity index (E*), the Simpson’s index of diversity (1 − D), the Shannon index (H′), and the Pianka index (Ojk). Xenopus gilli diet was more diverse than X. laevis, particularly in Kleimond where the Shannon index was nearly double. Both species were found to consume large amounts of tadpoles belonging to different amphibian species, including congeners, with an overall higher incidence of anurophagy than previously recorded. However, X. laevis also feeds on adult X. gilli, thus representing a direct threat for the latter. While trophic niche overlap was 0.5 for the CoGH, it was almost 1 in Kleinmond, suggesting both species utilise highly congruent trophic niches. Further, subdividing the dataset into three size classes revealed overlap to be higher in small frogs in both study sites. Our study underlines the importance of actively controlling X. laevis at sites with X. gilli in order to limit competition and predation, which is vital for conservation of the south-western Cape endemic.https://peerj.com/articles/3130/Publisher's versio

Responses of <i>Staphylococcus aureus</i> exposed to HCl and organic acid stress

Staphylococcus aureus is an important food poisoning bacterium. In food preservation, acidification is a well-known method. Permeant weak organic acids, like lactic and acetic acids, are known to be more effective against bacteria than inorganic strong acids (e.g., HCl). Growth experiments and metabolic and transcriptional analyses were used to determine the responses of a food pathogenic S. aureus strain exposed to lactic acid, acetic acid, and HCl at pH 4.5. Lactic and acetic acid stress induced a slower transcriptional response and large variations in growth patterns compared with the responses induced by HCl. In cultures acidified with lactic acid, the pH of the medium gradually increased to 7.5 during growth, while no such increase was observed for bacteria exposed to acetic acid or HCl. Staphylococcus aureus increased the pH in the medium mainly through accumulation of ammonium and the removal of acid groups, resulting in increased production of diacetyl (2,3-butanedione) and pyrazines. The results showed flexible and versatile responses of S. aureus to different types of acid stress. As measured by growth inhibition, permeant organic acid stress introduced severe stress compared with the stress caused by HCl. Cells exposed to lactic acid showed specific mechanisms of action in addition to sharing many of the mechanisms induced by HCl stress. </jats:p

Are invasive populations characterized by a broader diet than native populations?

International audienceBackground. Invasive species are among the most significant threats to biodiversity. The diet of invasive animal populations is a crucial factor that must be considered in the context of biological invasions. A broad dietary spectrum is a frequently cited characteristic of invasive species, allowing them to thrive in a wide range of environments. Therefore, empirical studies comparing diet in invasive and native populations are necessary to understand dietary requirements, dietary flexibility, and the associated impacts of invasive species.Methods. In this study, we compared the diet of populations of the African clawed frog, Xenopus laevis in its native range, with several areas where it has become invasive. Each prey category detected in stomach contents was assigned to an ecological category, allowing a comparison of the diversity of ecological traits among the prey items in the diet of native and introduced populations. The comparison of diets was also performed using evenness as a niche breadth index on all sampled populations, and electivity as a prey selection index for three out of the six sampled populations.Results. Our results showed that diet breadth could be either narrow or broad in invasive populations. According to diet and prey availability, zooplankton was strongly preferred in most cases. In lotic environments, zooplankton was replaced by benthic preys, such as ephemeropteran larvae.Discussion. The relative proportions of prey with different ecological traits, and dietary variability within and between areas of occurrence, suggest that X. laevis is a generalist predator in both native and invasive populations. Shifts in the realized trophic niche are observed, and appear related to resource availability. Xenopus laevis may strongly impact aquatic ecosystems because of its near complete aquatic lifestyle and its significant consumption of key taxa for the trophic relationships in ponds