Effect of swimming with the use of aqua fitness elements and interval hypoxic training on the physical fitness of boys aged 11-12 years

Aim: to establish the integrated effect of training sessions using elements of aqua fitness and interval hypoxic training on the special physical fitness of swimmers. Material: young swimmers participated in the study (n = 64, age 11-12, sporting experience - 2-3 years). The research was carried out in stages: before the experiment began, and then in 8, 16 and 24 weeks later. Frequency of classes in all groups was 6 times a week. Results: the ability to work in anaerobic alactatic, lactate and aerobic energy supply zones was studied. It was established that such training sessions help to improve the performance and capacity of the anaerobic alactatious system. The feasibility of such combination is proved by the growth of performance indicators in areas of aerobic, anaerobic alactatic and lactate energy supply. Conclusions: The feasibility of such training sessions is explained by: minimizing the negative impact on the children’s body of exercises on the development of force in conditions of the aquatic environment; improving the functional capabilities of the body

The effect of experienced individuals on navigation by king penguin chick pairs

Group members' individual experience can have important influences when navigating collectively. However, how exactly they structure group travel performance is still not fully understood. This study investigated how navigation and leadership dynamics are affected by the presence of an experienced individual in king penguin, Aptenodytes patagonicus, chick pairs. We tested pairs of chicks in which two partners differed in their level of prior navigational experience. Naïve pairs consisted of two chicks that had no previous homing experience. In mixed pairs, one chick was naïve, but the other chick had previous homing experience. Our results showed that in mixed pairs the navigational performance of naïve chicks improved if they travelled together with an experienced partner compared to when they walked alone. Experienced chicks, however, maintained their relatively high speeds and efficiencies irrespective of whether they walked with a partner or independently. We also observed a shift in leadership dynamics: in naïve pairs, both chicks took turns in leading and following, while in mixed pairs, experienced chicks tended to lead throughout. Our work provides a valuable empirical system in which to test theoretical models of leadership and information transfer within groups

Resolution of navigational conflict in king penguin chicks

Conflicts may arise within a moving animal group if its members have different preferred destinations. Many theoretical models suggest that in maintaining group cohesion conflicting preferences can have an overwhelming influence on decision making. However, empirical studies, especially on wild animals, remain limited. Here, we introduce a new study system for investigating collective decision making: king penguins, Aptenodytes patagonicus. Their gregarious lifestyle, the colony's organization into subgroups and group travel make king penguins especially interesting for studying collective movements. Chicks spend their first year of life in groups with other chicks (crèches), and if displaced will return to their crèche. We examined how different levels of navigational conflict affect such homing, by comparing the performance of pairs of chicks from the same crèche with pairs from different crèches. The majority of chicks in both treatments travelled at least part of the journey together; when doing so they were more efficient and faster than individuals travelling alone. Chicks took turns in leading and following. Chicks with a common destination (same-crèche pairs) were more precise at homing and less likely to split up than those with a conflict over preferred destinations (different-crèche pairs). Our results support some, but not all, predictions derived from theoretical models

Reactivation of the Paternal X Chromosome in Early Mouse Embryos

It is generally accepted that paternally imprinted X inactivation occurs exclusively in extraembryonic lineages of mouse embryos, whereas cells of the embryo proper, derived from the inner cell mass (ICM), undergo only random X inactivation. Here we show that imprinted X inactivation, in fact, occurs in all cells of early embryos and that the paternal X is then selectively reactivated in cells allocated to the ICM. This contrasts with more differentiated cell types where X inactivation is highly stable and generally irreversible. Our observations illustrate that an important component of genome plasticity in early development is the capacity to reverse heritable gene silencing decisions

Studies of biominerals and related novel nanoscale composite materials

Biomineralised structures are composite materials formed in diverse biological systems. Their composition, distribution and functions are described together with several technological applications. Illustrative examples include the use of coral in reconstructive surgery and the development of flexible macro-defect-free concrete. Recent studies of biomineralisation in the chiton Cryptoplax striata have further extended understanding of the initial stages of iron biomineral formation, a prominent feature of radula teeth structure in the marine molluscs, chitons and limpets. In the marine gastropod Nerita atramentosa, a novel motif of tooth structure is reported, where granules (300 nm - 1.5 μm) are embedded in the organic matrix. Further studies of biomineralisation at the nanoscale level, utilising the hollow spherical protein ferritin and several polysaccharides, reveal the nanotechnological possibilities of such research, creating varied multi-layered nanocomposites and extended arrays

Establishment of histone H3 methylation on the inactive X chromosome requires transient recruitment of Eed-Enx1 polycomb-group complexes.

AbstractPrevious studies have implicated the Eed-Enx1 Polycomb group complex in the maintenance of imprinted X inactivation in the trophectoderm lineage in mouse. Here we show that recruitment of Eed-Enx1 to the inactive X chromosome (Xi) also occurs in random X inactivation in the embryo proper. Localization of Eed-Enx1 complexes to Xi occurs very early, at the onset of Xist expression, but then disappears as differentiation and development progress. This transient localization correlates with the presence of high levels of the complex in totipotent cells and during early differentiation stages. Functional analysis demonstrates that Eed-Enx1 is required to establish methylation of histone H3 at lysine 9 and/or lysine 27 on Xi and that this, in turn, is required to stabilize the Xi chromatin structure