Origins and fate of fungi and bacteria in the gut of Lumbricus terrestris L. studied by image analysis

The effect of the passage through the gut of the earthworm Lumbricus terrestris L. on fungi and bacteria ingested with decomposing leaves of Taraxacum officinale and with soil was quantified using image analysis tools. Both leaf and soil material were labeled with fluorescent latex microbeads to allow a quantification of the food sources in the fore-, mid-, and hindgut of the earthworms. The content of leaf material in the gut varied in a range between 4 and 59% of the total gut content in different earthworms and the different parts of the intestine of individual animals. Filamentous fungi in the gut compartments were found to originate mainly from leaf material (7700±1800 μg (g leaf (dry wt.))−1), however, the major part was disrupted before arriving in the intestine. Remaining hyphae in the foregut with a biomass of up to 900±150 μg (g gut content (dry wt.))−1 were completely digested during passage through the earthworm gut. Spores of fungi were not detected in our studies. Bacterial cell numbers in the gut compartments ranged from 63±5×108 to 327±16×108 (g gut content (dry wt.))−1 and were significantly higher than the numbers found in the soil (50±1×108 cells (g soil (dry wt.))−1). Cell numbers usually increased from fore- to hindgut. This increase was not correlated to contents of organic material and only partially due to a multiplication of bacterial cells. Numbers of dividing cells accounted in total for approximately 12% of all bacteria, increasing significantly from fore- to hindgut, counts were from 10±1×108 to 25±2×108 (g gut content (dry wt.))−1, respectively. Average cell volumes of bacteria calculated from cell size distributions in leaf and soil material differed significantly, being 0.197 and 0.063 μm3, respectively. In the gut compartments, average cell volumes ranged from 0.043 to 0.070 μm3, which may indicate the disruption of large cells originating from the leaves before arriving in the foregu

Assessing the national identity and sense of belonging of students in Germany with immigration backgrounds

Students in Germany score low on national identity when it is measured with national symbols Students with immigration backgrounds show lower national identity scores in 20 countries Over 90% of German students with immigration backgrounds feel a sense of belonging to Germany. Research instruments measuring national identity must consider transnationality and fluidity. Purpose: This paper aims to analyse the data regarding the national identification and sense of belonging of secondary school students with and without immigration backgrounds collected through the International Civic and Citizenship Study 2016. It also assesses whether the research instruments used are suitable for the German context. Method: Likert scale items measured national identification. Acculturation theory based categories were employed to measure the sense of belonging.  Differences between students across and within countries were assessed using t tests. Findings: Students with immigration backgrounds tend to present statistically lower scores for the scale ‘attitudes toward country of residence’ in 20 of 24 participating countries. In international comparison, German students with and without immigration backgrounds score relatively low on all five items of the scale. Despite achieving significantly lower scores for national identification, 90% of students in Germany with immigration backgrounds feel a sense of belonging to Germany

Analysis of Frankia populations in three soils devoid of actinorhizal plants

Frankia populations were analyzed in three soils devoid of actinorhizal plants but containing monocultures of birch (Betula pendula Roth), pine (Pinus sylvestris L.) or spruce (Picea abies (L.) Karsten). Bioassays using seedlings of Alnus incana as capture plants resulted in nodulation capacities of 3160±7, 2267±13, and 2747±6 nodulation units g−1 of these soils, respectively. Comparative sequence analysis of an actinomycetes-specific insertion in domain III of the 23S rRNA allowed a grouping of isolates obtained from nodules of the capture plants into three distinct groups of the Alnus host infection group. This separation was confirmed by the analysis of genomic fingerprints of the isolates generated by rep-PCR fingerprinting with the BOX primer. Genomic fingerprints also demonstrated that all isolates differed from each other. The isolates accounted for a significant proportion of the Frankia population in root nodules of the capture plants as shown by in situ hybridization with specific probes. However, only those Frankia strains isolated from soil of the birch stand via Alnus seemed to represent the total Frankia population in root nodules. Nodules induced after inoculation with soil from the pine or spruce stand also contained Frankia populations which were not isolated during this study and which could not be identified by in situ hybridization. Depending upon whether the soil originated from a birch, pine or spruce stand, different Frankia populations were found in the nodules of the capture plants. Because a nested PCR on nucleic acids extracted from these different soils did not indicate differences in the diversity of the total Frankia populations, it was concluded that Frankia populations in nodules of the capture plants represent the fraction of physiologically active, infecting frankiae in the soils rather than the total Frankia populatio