The importance of fission–fusion social group dynamics in birds

Almost all animal social groups show some form of fission–fusion dynamics, whereby group membership is not spatio‐temporally stable. These dynamics have major implications at both population and individual levels, exerting an important influence on patterns of social behaviour, information transfer and epidemiology. However, fission–fusion dynamics in birds have received relatively little attention. We review the existing evidence for fission–fusion sociality in birds alongside a more general explanation of the social and ecological processes that may drive fission–fusion dynamics. Through a combination of recent methodological developments and novel technologies with well‐established areas of ornithological research, avian systems offer great potential to further our understanding of fission–fusion social systems and the consequences they have at an individual and population level. In particular, investigating the interaction between social structure and environmental covariates can promote a deeper understanding of the evolution of social behaviour and the adaptive value of group living, as well as having important consequences for applied research.     

Shielding effect of monovalent and divalent cations on solid-phase DNA hybridization: surface plasmon resonance biosensor study

Solid-phase hybridization, i.e. the process of recognition between DNA probes immobilized on a solid surface and complementary targets in a solution is a central process in DNA microarray and biosensor technologies. In this work, we investigate the simultaneous effect of monovalent and divalent cations on the hybridization of fully complementary or partly mismatched DNA targets to DNA probes immobilized on the surface of a surface plasmon resonance sensor. Our results demonstrate that the hybridization process is substantially influenced by the cation shielding effect and that this effect differs substantially for solid-phase hybridization, due to the high surface density of negatively charged probes, and hybridization in a solution. In our study divalent magnesium is found to be much more efficient in duplex stabilization than monovalent sodium (15 mM Mg²⁺ in buffer led to significantly higher hybridization than even 1 M Na⁺). This trend is opposite to that established for oligonucleotides in a solution. It is also shown that solid-phase duplex destabilization substantially increases with the length of the involved oligonucleotides. Moreover, it is demonstrated that the use of a buffer with the appropriate cation composition can improve the discrimination of complementary and point mismatched DNA targets.     

Analysis of extra‐pair paternity and conspecific brood parasitism in mallards Anas platyrhynchos using non‐invasive techniques

A method that was based on non‐invasive sampling of genetic material was used to determine the rates of extra‐pair paternity (EPP) and conspecific brood parasitism (CBP) in mallards. Maternal and offspring DNA were extracted from feathers in nest material and hatched eggshell membranes. Using 8 microsatelite loci, extra‐pair offspring were detected in 48% of nests and accounted for 9.3% of all offspring. In addition, 10.1% of the offspring were confirmed to result from CBP, and 24% of all nests contained at least 1 offspring from CBP. Rates of conspecific nest parasitism were higher than those of related species, which might have been due to higher breeding densities at our study site. The incidence of EPP was distributed randomly (i.e. did not deviate from bionomial distribution) throughout the population, indicating that variations in pre‐copulatory (e.g. female choice, mate guarding) or post‐copulatory processes (e.g. sperm competition, cryptic female choice) do not affect the distribution of EPP among breeding pairs markedly. Yet, our data provide evidence of variation in the risk of being parasitized among breeding females. The occurrence of CBP and EPP was unaffected by the timing of the breeding attempt or breeding synchrony.     

Mechanisms determining the morphology of the peripheral ER

The endoplasmic reticulum (ER) consists of the nuclear envelope and a peripheral network of tubules and membrane sheets. The tubules are shaped by the curvature-stabilizing proteins reticulons and DP1/Yop1p, but how the sheets are formed is unclear. Here, we identify several sheet-enriched membrane proteins in the mammalian ER, including proteins that translocate and modify newly synthesized polypeptides, as well as coiled-coil membrane proteins that are highly upregulated in cells with proliferated ER sheets, all of which are localized by membrane-bound polysomes. These results indicate that sheets and tubules correspond to rough and smooth ER, respectively. One of the coiled-coil proteins, Climp63, serves as a "luminal ER spacer" and forms sheets when overexpressed. More universally, however, sheet formation appears to involve the reticulons and DP1/Yop1p, which localize to sheet edges and whose abundance determines the ratio of sheets to tubules. These proteins may generate sheets by stabilizing the high curvature of edges.     

Grip force variability and its effects on children's handwriting legibility, form, and strokes

A comprehensive understanding of the underlying biomechanical processes during handwriting is needed to accurately guide clinical interventions. To date, quantitative measurement of such biomechanical processes has largely excluded measurements of the forces exerted radially on the barrel of the writing utensil (grip forces) and how they vary over time during a handwriting task. An instrumented writing utensil was deployed for a direct measurement of kinematic and temporal information during a writing task, as well as forces exerted on the writing surface and on the barrel of the pen. The writing utensil was used by a cohort of 35 students (19 males), 16 in first grade and 19 in second grade, as they performed the Minnesota Handwriting Assessment (MHA) test. Quantitative grip force variability measures were computed and tested as correlates of handwriting legibility, form, and strokes. Grip force variability was shown to correlate strongly with handwriting quality, in particular for students classified by the MHA as nonproficient writers. More specifically, static grip force patterns were shown to result in poor handwriting quality and in greater variation in handwriting stroke durations. Grip force variability throughout the writing task was shown to be significantly lower for nonproficient writers (t-test, p<0.01) while the number of strokes and per-stroke durations were shown to be higher (p<0.03). The results suggest that grip force dynamics play a key role in determining handwriting quality and stroke characteristics. In particular, students with writing difficulties exhibited more static grip force patterns, lower legibility and form scores, as well as increased variation in stroke durations. These findings shed light on the underlying processes of handwriting and grip force modulation and may help to improve intervention planning.     

Factors influencing the production of stilbenes by the knotweed, <Emphasis Type="Italic">Reynoutria</Emphasis> × <Emphasis Type="Italic">bohemica</Emphasis>

Background  

Japanese knotweed, Reynoutria japonica, is known for its high growth rate, even on adverse substrates, and for containing organic substances that are beneficial to human health. Its hybrid, Reynoutria × bohemica, was described in the Czech Republic in 1983 and has been widespread ever since. We examined whether Reynoutria × bohemica as a medicinal plant providing stilbenes and emodin, can be cultivated in spoil bank substrates and hence in the coalmine spoil banks changed into arable fields. We designed a pot experiment and a field experiment to assess the effects of various factors on the growth efficiency of Reynoutria × bohemica on clayish substrates and on the production of stilbenes and emodin in this plant.