Ciliate community structure and interactions within the planktonic food web in two alpine lakes of contrasting transparency

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Behavioural Type Affects Space Use in a Wild Population of Crows (Corvus corone)

While personality‐dependent dispersal is well studied, local space use has received surprisingly little attention in this context, despite the multiple consequences on survival and fitness. Regarding the coping style of individuals, recent studies on personality‐dependent space use within a habitat indicate that ‘proactive’ individuals are wider ranging than ‘reactive’ ones. However, such studies are still scarce and cover limited taxonomic diversity, and thus, more research is needed to explore whether this pattern generalises across species. We examined the link between coping style and space use in a population of crows (Corvus corone) freely inhabiting the urban zoo of Vienna, Austria. We used a binary docility rating (struggle during handling vs. no struggle) and a tonic immobility test to quantify individual coping style. Individual space use was quantified as the number of different sites at which each crow was observed, and we controlled for different number of sightings per individual by creating a space use index. Only the binary docility rating showed repeatability over time, and significantly predicted space use. In contrast to previous studies, we found that reactive crows (no struggle during handling) showed wider ranging space use within the study site than proactive individuals (who struggled during handling). The discrepancy from previous results suggests that the relationship between behavioural type and space use may vary between species, potentially reflecting differences in socioecology.     

S100A11 plays a role in homologous recombination and genome maintenance by influencing the persistence of RAD51 in DNA repair foci

The repair of DNA double-strand breaks (DSBs) by homologous recombination (HR) is an essential process in maintenance of chromosomal stability. A key player of HR is the strand exchange factor RAD51 whose assembly at sites of DNA damage is tightly regulated. We detected an endogenous complex of RAD51 with the calcium-binding protein S100A11, which is localized at sites of DNA repair in HaCaT cells as well as in normal human epidermal keratinocytes (NHEK) synchronized in S phase. In biochemical assays, we revealed that S100A11 enhanced the RAD51 strand exchange activity. When cells expressing a S100A11 mutant lacking the ability to bind Ca²⁺, a prolonged persistence of RAD51 in repair sites and nuclear γH2AX foci was observed suggesting an incomplete DNA repair. The same phenotype became apparent when S100A11 was depleted by RNA interference. Furthermore, down-regulation of S100A11 resulted in both reduced sister chromatid exchange confirming the restriction of the recombination capacity of the cells, and in an increase of chromosomal aberrations reflecting the functional requirement of S100A11 for the maintenance of genomic stability. Our data indicate that S100A11 is involved in homologous recombination by regulating the appearance of RAD51 in DSB repair sites. This function requires the calcium-binding activity of S100A11.     

Effect of organic carbon sources and environmental factors on cell growth and lipid content of Pavlova lutheri

The present study aimed to investigate the effects of organic carbon sources, cultivation methods, and environmental factors on growth and lipid content of Pavlova lutheri for biodiesel production. In the 250-mL flask bioreactors, P. lutheri was cultivated in the modified artificial seawater (ASW) medium containing glucose, glycerol, sodium acetate, or sucrose as an organic carbon substrate. The effects of different growth conditions (phototrophic, mixotrophic, and heterotrophic) and environmental factors such as photoperiod, light intensity, and salinity were evaluated. Growth of P. lutheri was inhibited under heterotrophy but was enhanced in mixotrophy as compared to phototrophy. Biomass and lipid content of P. lutheri were significantly (p < 0.05) affected by changing photoperiod, light intensity, and salinity. Higher biomass concentration and lipid content were observed at a light intensity of 100 ± 2 μmol photons m−2 s−1, 18 h photoperiod, and 30% salinity, in a modified ASW medium supplemented with 10 mmol sucrose. An increase in biomass concentration from 320 ± 25.53 to 1106 ± 18.52 mg L−1 and high lipid content of 31.11 ± 1.65% (w/w) were observed with the optimized culture conditions, demonstrating a significant (p < 0.05) enhancement in biomass and lipid content due to the improved culture conditions. The present study emphasizes the possible use of sucrose for biomass and lipid production with P. lutheri under the optimized culture conditions. Using low-cost and relatively easy accessible feedstock such as sucrose would be a valuable alternative for growing microalgae with enhanced lipid content.