Biology subjects

G, R.

Publications and source records attributed to G, R..

4 recordsLinked to original sources

bioRxiv2024

Do invasive tetrapods conserve their climatic niches?

Invasive species are the second biggest threat to biodiversity after habitat fragmentation. The species list was collated from the Global Invasive Species Database (GISD) and the Centre for Agricultural and Bioscience International (CABI), and the species occurrence data were downloaded from the Global Biodiversity Information Facility (GBIF). This study examines the niche dynamics of 152 invasive tetrapods and finds that 60% of the species have very low or low niche overlap across the native and introduced regions. There are species with very high niche overlap, such as the Cane toad, Brahminy blind snake, Eurasian collared dove, Whitehead marmoset and Asian house shrew. Around 30% (=46) of species are showing considerable niche expansion. Similarly, 21 species (5 amphibians, 6 reptiles, 6 birds and 4 mammals) show no expansion in the introduced region. The introduction pattern presents that 46 invasive tetrapods are native to Asia, whereas 43 of them are introduced to North America.

ecology↗

bioRxiv2023

Coherence-based interhemispheric EEG functional connectivity changes in distinct frequency bands during eyes open meditation

Meditation is a self-regulatory process practiced primarily to reduce stress, manage emotions and mental health. The objective was to study the information exchange between symmetric electrodes across the hemispheres during meditation using functional connectivity (FC) measures. We investigate the changes in the coherence between EEG electrode pairs during the meditation practiced by long-term Brahmakumaris Rajyoga meditators with open eyes and during listening to music by controls as the comparable task. Two distinct FC measures derived from coherency, namely, magnitude squared coherence (MSC) and imaginary part of coherency (ICoh) are used to study the changes in interhemispheric coherence. During baseline conditions, higher MSC is found in meditators in frontocentral and centroparietal regions and higher |ICoh| globally in higher beta and gamma bands than controls. Further, in meditators, the MSC significantly increases in higher theta and alpha bands in the frontal and parietal regions and |ICoh| significantly decreases across all regions and bands except in the alpha band during meditation. However, the control subjects with no knowledge of meditation show no change in theta or alpha MSC or |ICoh| during the music session. Distinct patterns of changes are observed with the two FC measures in different frequency bands during meditation in the meditators and music-listening session in the control subjects indicating varied information processing between the right and left hemispheres and differences in the FC measures used. We found increased MSC and decreased |ICoh| between the frontal electrodes implying increased self-awareness in meditators. The MSC between the occipital electrodes in meditators is less than the controls in baseline condition indicating a possible modified visual information processing in Rajyoga meditators due to the long-term practice of meditation with open eyes. Overall, the changes in MSC indicate increased functional integration during meditation supporting the hypothesis of cortical integration theory.

neuroscience↗

bioRxiv2022

Regenerative Agriculture Augments Bacterial Community Structure for a Healthier Soil and Agriculture

Use of chemical fertilization and pesticides not only harm the environment but also have detrimental consequences on human health. In recent years, there has been a major emphasis worldwide on natural agriculture methods. Regenerative agriculture is known across the world as a combination of nature-friendly farming practices such as no-till, cover cropping, crop-rotation, agro-forestry and use of organic home-based/farm-based ingredients to revive soil health. In India, a number of farmers are slowly adopting these practices using home-based mixtures and farmyard manure for soil rejuvenation and pest management. In order to evaluate the efficacy of the regenerative agriculture practices, this study compared conventional and regenerative agriculture plots for their soil bacterial and nutrient profiles. Two crops - ragi and vegetable (tomato/beans), and different lengths ([≤]3 and >5 years) of regenerative practices were additional metrics considered to understand variabilities due to crop-type and period of application. We found that all regenerative practices were effective in bringing about an enrichment for soil bacteria with a more heterogeneous composition. Additionally, the regenerative vegetable (RV) plots had an enhanced representation of Actinobacteriota, Chloroflexi, Cyanobacteria and Patescibacteria in comparison to conventional vegetable (CV) plots and Barren land (BL). Similarly, the regenerative ragi (RR) plots saw higher representation of Firmicutes and Actinobacteriota in comparison to conventional ragi (CR) plots and BL. The RV plots were also found to be enriched for Plant Growth Promoting Rhizobacteria (PGPRs) - Pseudomonas sp., and RR plots were enriched for Bacillus sp., and Mesorhizobium sp., which are known to play significant roles in vegetable and ragi growth respectively. Interestingly, long-term regenerative agriculture was able to support good nutrient composition while enhancing Soil Organic Carbon (SOC) levels. In all, the regenerative agriculture practices were found to be effective in improving bacterial community structure and simultaneously improving soil health. We found that BL soil with eucalyptus plantation showed least bacterial diversity suggesting detrimental impact on soil health.

ecology↗

bioRxiv2019

No association of mitochondrial DNA levels in trophectodermal cells with the developmental competence of the blastocyst and pregnancy outcomes

Study questionCan mitochondrial DNA (mtDNA) levels in trophectodermal cells of the blastocyst predict the blastocyst quality, ploidy status, implantation rate and clinical outcomes?\n\nSummary answermtDNA levels in trophectodermal cells of the blastocyst do not associate with the blastocyst quality, ploidy status, implantation potential and clinical outcomes, but can differentiate between aneuploid and euploid blastocysts.\n\nWhat we already knowmtDNA levels in the trophectodermal cells have been suggested to be associated with blastocyst morphology, ploidy and implantation rates, and has been proposed as biomarker to access blastocyst quality and predict clinical outcomes. However, discrepancies exist if mtDNA levels could serve as a marker for the same.\n\nStudy design and durationRetrospective analysis of mtDNA levels in trophectodermal cells obtained from blastocysts undergoing preimplantation genetic testing for aneuploidy (PGT-A) at Craft Hospital & Research Center, Kerala from January 2016-July 2017.\n\nParticipants/materials and methodsStudy included data from 287 blastocyst from (61) couples who underwent PGT-A using next generation sequencing (NGS). Levels of mtDNA in trophectodermal cells of the blastocyst were estimated by the NGS. Comparison of mtDNA levels with maternal age, blastocyst morphology, ploidy status, implantation rates, miscarriage rates and live birth rate was done.\n\nMain resultsThe levels of mtDNA in the trophectoderm of the blastocyst did not correlate with maternal age. There was no significant difference in the mtDNA levels between grade 1 and grade 2 blastocyst. Euploid blastocyst had significantly lower amounts of mtDNA levels in trophectodermal cells of the blastocyst were compared to aneuploid blastocyst. No significant differences were seen between mtDNA levels and implanting and non-implanting blastocysts or those resulted into miscarriage or live birth.\n\nLimitationsThe study is limited by a small sample size and hence type II error cannot be ruled out.\n\nWider ImplicationsThe study does not support the potential use of mtDNA levels in the trophectodermal cells as biomarker for blastocyst quality and predicting clinical outcomes needs.\n\nStudy funding/competing interest(s)There is no external funding for the study. There is no conflict of interest.

developmental biology↗