Astrocytes and diffusive spread of substances in brain extracellular space

Brain function is based on communication between individual cells, neurons and glia. From a traditional point of view, neurons play a central role in the fast transfer of information in the central nervous system while astrocytes, major type of glia, serve as housekeeping elements maintaining homeostasis of the extracellular microenvironment. This view has dramatically changed in recent years as many findings ascribe new roles to astrocytes. It is becoming evident that astrocytes communicate with neurons via chemical signals released to the extracellular space (ECS). Astrocytes also have communication systems of their own, such as calcium waves that use gap junctions in combination with purinergic signaling through the ECS. Here we discuss yet another important role for astrocytes: that they regulate diffusion of signaling molecules and therapeutic agents in the extracellular microenvironment by contributing to the structural properties of ECS. There is a wealth of morphological data showing that each astrocyte is an exclusive occupant of a small volume of brain tissue, and that many fine astrocytic processes ensheathe neuronal processes and bodies. The functional significance of these unique morphological features is largely unknown with the exception of astrocytic coverage of synaptic formations. At the synapses, astrocytic processes play an active role by restricting neurotransmitter diffusion to the synaptic cleft and its immediate vicinity. Recent work suggests that astrocytic processes work in a similar fashion throughout the ECS and thus control the diffusive spread of substances over both short and long distances

Response of transient soil waterlogging on shoot growth pattern and root architecture of finger millet and barnyard millet seedlings

Millets, as key crops in semi-arid and arid tropical regions, are gaining recognition for their nutritional benefits and resilience to challenging conditions. Finger millet and barnyard millet, in particular, stand out for their nutrient profiles and adaptability. However, research on their response to waterlogging, a major abiotic stress, remains limited. This study aimed to examine the immediate response of finger millet and barnyard millet seedlings to transient waterlogging conditions, focusing on their growth patterns and changes in root architecture to understand their morpho-physiological adaptive strategy. Seedlings were subjected to varying durations of waterlogging: control, 48, 74, and 120 hours to assess parameters such as shoot and root characteristics, leaf growth, and tolerance indices. Results showed a decrease in root length and an increase in shoot length with prolonged waterlogging. Root and shoot biomass, along with seedling dry weight, rose as waterlogging durations increased. Significant increases were observed in root surface area, volume, and the number of root tips and forks. Leaf area initially expanded but declined after 72 hours of waterlogging, accompanied by changes in specific leaf area and chlorophyll concentration. Tolerance indices, such as root-to-shoot ratio, decreased under waterlogging conditions, with finger millet exhibiting higher tolerance than barnyard millet. These findings provide insights into the adaptive strategies of millets under waterlogging, which is valuable for crop management and breeding for enhanced stress tolerance

Oxidation products of DNA, lipid and protein among the individuals progressing towards metabolic syndrome

Oxidative stress (OS) is an early event and at the same time also a consequence in the pathology of MetS. We investigated if oxidation markers of DNA, lipid and protein increased with an increase in the risk parameters of MetS. Participants (male:70, female:90 ≥ 20 yrs) were categorized based on the number of risk factors they had as 3 Risk, 2 Risk, 1 Risk and 0 Risk for MetS and were evaluated for various oxidation markers. Protein carbonyl and advanced oxidation protein product (protein oxidation marker) differed significantly between the four study group while malondialdehyde and hydroxynonenal (lipid peroxidation marker) did not. “8-OH dG” (DNA oxidation marker) differed significantly (P< 0.05) while total antioxidant capacity did not demonstrate significant difference in its values across the group (P> 0.05). Pairwise comparison for statistically significant markers(Protein oxidation markers and 8-OH dG), demonstrated that only 8-OH dG differed significantly between 0 Risk- 3 Risk (P< 0.012) but not between 0 Risk -2 Risk and 0 Risk-1 Risk. Oxidative stress markers of DNA, lipid and protein do not increase with an increase in the risk parameters of MetS. However, it is indeed high in MetS with 3 and more risk parameters. Presence of 2 or 1 Risk also increases OS compared to 0 Risk. There is oxidative stress damage in MetS to lipid and protein but DNA damage was of significant consequence

Astrocytes and diffusive spread of substances in brain extracellular space

Brain function is based on communication between individual cells, neurons and glia. From a traditional point of view, neurons play a central role in the fast transfer of information in the central nervous system while astrocytes, major type of glia, serve as housekeeping elements maintaining homeostasis of the extracellular microenvironment. This view has dramatically changed in recent years as many findings ascribe new roles to astrocytes. It is becoming evident that astrocytes communicate with neurons via chemical signals released to the extracellular space (ECS). Astrocytes also have communication systems of their own, such as calcium waves that use gap junctions in combination with purinergic signaling through the ECS. Here we discuss yet another important role for astrocytes: that they regulate diffusion of signaling molecules and therapeutic agents in the extracellular microenvironment by contributing to the structural properties of ECS. There is a wealth of morphological data showing that each astrocyte is an exclusive occupant of a small volume of brain tissue, and that many fine astrocytic processes ensheathe neuronal processes and bodies. The functional significance of these unique morphological features is largely unknown with the exception of astrocytic coverage of synaptic formations. At the synapses, astrocytic processes play an active role by restricting neurotransmitter diffusion to the synaptic cleft and its immediate vicinity. Recent work suggests that astrocytic processes work in a similar fashion throughout the ECS and thus control the diffusive spread of substances over both short and long distances

Gut microbiota composition in himalayan and andean populations and its relationship with diet, lifestyle and adaptation to the high-altitude environment

Human populations living at high altitude evolved a number of biological adjustments to cope with a challenging environment characterised especially by reduced oxygen availability and limited nutritional resources. This condition may also affect their gut microbiota composition. Here, we explored the impact of exposure to such selective pressures on human gut microbiota by considering different ethnic groups living at variable degrees of altitude: the high-altitude Sherpa and low-altitude Tamang populations from Nepal, the high-altitude Aymara population from Bolivia, as well as a low-altitude cohort of European ancestry, used as control. We thus observed microbial profiles common to the Sherpa and Aymara, but absent in the low-altitude cohorts, which may contribute to the achievement of adaptation to high-altitude lifestyle and nutritional conditions. The collected evidences suggest that microbial signatures associated to these rural populations may enhance metabolic functions able to supply essential compounds useful for the host to cope with high altitude-related physiological changes and energy demand. Therefore, these results add another valuable piece of the puzzle to the understanding of the beneficial effects of symbiosis between microbes and their human host even from an evolutionary perspective

Reconstructing the complex colonisation histories of lizards across Mediterranean archipelagos

Aim: The Mediterranean Basin is a global biodiversity hotspot and has one of the longest histories of human–biota interactions. Islands host a large fraction of Mediterranean diversity and endemism, but the relative importance of natural versus human-mediated colonisation processes in shaping the distribution and genetic structure of Mediterranean island fauna remains poorly understood. Here, we combine population genomics, demographic models and palaeoshoreline reconstructions to establish the island-colonisation dynamics of wall lizards in Mediterranean archipelagos. Location: Four Mediterranean archipelagos in Italy and Croatia. Taxon: The wall lizard Podarcis siculus. Methods: We used ddRAD sequencing to genotype 140 lizards from 23 island and mainland populations. Analyses of admixture and site frequency spectra were used to reconstruct population structure, demographic history and variation of gene flow through time. Genomic results were integrated with palaeogeographical reconstructions and were compared to archaeological evidence of human presence on these islands. Results: Although many island populations of this species are assumed to be non-native, we find that many islands were colonised long before any known human settlements (230,000–12,000 years ago). This natural colonisation most likely occurred through land bridges during glacial marine regression or by over-sea rafting. On the other hand, islands distant from the continent were often colonised recently, and some of the estimated island colonisation times match historical records of human arrival. We also determine that long-established island populations generally show lower genetic diversity compared to proximate mainland populations, contrary to recently colonised islands that must have experienced higher rates of post-colonisation gene flow. Main Conclusion: Our integrated approach provides us with the power to accurately quantify the origin, timing and mode of island colonisation. This framework helps to clarify the biogeographical and evolutionary history of island populations, with important implications for conservation and management of island biodiversity