Organizational Heterogeneity of Vertebrate Genomes

Genomes of higher eukaryotes are mosaics of segments with various structural, functional, and evolutionary properties. The availability of whole-genome sequences allows the investigation of their structure as “texts” using different statistical and computational methods. One such method, referred to as Compositional Spectra (CS) analysis, is based on scoring the occurrences of fixed-length oligonucleotides (k-mers) in the target DNA sequence. CS analysis allows generating species- or region-specific characteristics of the genome, regardless of their length and the presence of coding DNA. In this study, we consider the heterogeneity of vertebrate genomes as a joint effect of regional variation in sequence organization superimposed on the differences in nucleotide composition. We estimated compositional and organizational heterogeneity of genome and chromosome sequences separately and found that both heterogeneity types vary widely among genomes as well as among chromosomes in all investigated taxonomic groups. The high correspondence of heterogeneity scores obtained on three genome fractions, coding, repetitive, and the remaining part of the noncoding DNA (the genome dark matter - GDM) allows the assumption that CS-heterogeneity may have functional relevance to genome regulation. Of special interest for such interpretation is the fact that natural GDM sequences display the highest deviation from the corresponding reshuffled sequences

Vulnerability and impacts of climate change on forest and freshwater wetland ecosystems in Nepal: A review

Climate change (CC) threatens ecosystems in both developed and developing countries. As the impacts of CC are pervasive, global, and mostly irreversible, it is gaining worldwide attention. Here we review vulnerability and impacts of CC on forest and freshwater wetland ecosystems. We particularly look at investigations undertaken at different geographic regions in order to identify existing knowledge gaps and possible implications from such vulnerability in the context of Nepal along with available adaptation programs and national-level policy supports. Different categories of impacts which are attributed to disrupting structure, function, and habitat of both forest and wetland ecosystems are identified and discussed. We show that though still unaccounted, many facets of forest and freshwater wetland ecosystems of Nepal are vulnerable and likely to be impacted by CC in the near future. Provisioning ecosystem services and landscape-level ecosystem conservation are anticipated to be highly threatened with future CC. Finally, the need for prioritizing CC research in Nepal is highlighted to close the existing knowledge gap along with the implementation of adaptation measures based on existing location specific traditional socio-ecological system