Significant loss of mitochondrial diversity within the last century due to extinction of peripheral populations in eastern gorillas

Species and populations are disappearing at an alarming rate as a direct result of human activities. Loss of genetic diversity associated with population decline directly impacts species' long-term survival. Therefore, preserving genetic diversity is of considerable conservation importance. However, to assist in conservation efforts, it is important to understand how genetic diversity is spatially distributed and how it changes due to anthropogenic pressures. In this study, we use historical museum and modern faecal samples of two critically endangered eastern gorilla taxa, Grauer's (Gorilla beringei graueri) and mountain gorillas (Gorilla beringei beringei), to directly infer temporal changes in genetic diversity within the last century. Using over 100 complete mitochondrial genomes, we observe a significant decline in haplotype and nucleotide diversity in Grauer's gorillas. By including historical samples from now extinct populations we show that this decline can be attributed to the loss of peripheral populations rather than a decrease in genetic diversity within the core range of the species. By directly quantifying genetic changes in the recent past, our study shows that human activities have severely impacted eastern gorilla genetic diversity within only four to five generations. This rapid loss calls for dedicated conservation actions, which should include preservation of the remaining peripheral populations.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Increased chromosome 20 copy number detected by fluorescence in situ hybridization (FISH) in malignant melanoma

DNA amplification is an important mechanism of tumor progression that allows cancer cells to up-regulate the expression of critical genes such as oncogenes and genes conferring drug resistance. Recent studies using comparative genomic hybridization (CGH) revealed increased DNA copies of 20q sequences in 7 melanoma cell lines and 8 archival metastatic melanoma lesions. To evaluate chromosome 20 abnormalities in more detail and to resolve discrepancies between karyotype and CGH findings, we performed FISH analysis of metaphase cells in 13 melanoma cell lines (including the 7 lines used for CGH) and 9 primary melanoma specimens by using a whole chromosome paint specific for chromosome 20. All 13 cell lines (100%) and 8/9 primary tumors (89%) showed extra copies of chromosome 20 relative to tumor ploidy. Additionally, 6/14 cell lines (43%) and 2/8 primary tumors (25%) showed translocated chromosome 20 material previously undetected by standard cytogenetics. Cytologic evidence for gene amplification was also found in one cell line, which contained an add(20)(p 13), with additional DNA being derived from 20q sequences. These data suggest that overrepresentation of a gene or genes important for melanoma pathogenesis resides on the long arm of chromosome 20.link_to_subscribed_fulltex