Project description:How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Native Americans diversified into two basal genetic branches around 13 KYA, one in North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians and Australo-Melanesians, the latter possibly through the ancestors of Aleutian Islanders. Putative relict populations in South America, including the historical Pericúes and Fuego-Patagonians, are not directly related to modern Australo-Melanesians.
Project description:Esophageal squamous cell carcinoma (ESCC) is an aggressive cancer with one of the highest world incidences in the Eastern Cape region of South Africa. Several genome wide studies have been performed on ESCC cohorts from Asian countries, North America, Malawi and other parts of the world but none has been conducted on ESCC tumors from South Africa to date, where the molecular pathology and etiology of this disease remains unclear. We report here tumor associated copy number changes observed in 51 ESCC patients’ samples from the Eastern Cape province of South Africa. We extracted tumor DNA from 51 archived ESCC specimens and interrogated tumor associated DNA copy number changes using Affymetrix® 500K SNP array technology. The Genomic Identification of Significant Targets in Cancer (GISTIC) algorithm was applied to identify significant focal regions of gains and losses. Gains of the top recurrent cancer genes were validated by fluorescence in situ hybridization and their protein expression assessed by immunohistochemistry. Twenty-three significant focal gains were identified across samples. Gains involving the CCND1, MYC, EGFR and JAG1 loci recapitulated those described in studies on Asian and Malawian cohorts. The two most significant gains involved the chromosomal sub-bands 3q28, encompassing the TPRG1 gene and 11q13.3 including the CTTN, PPFIA1and SHANK2 genes. There was no significant homozygous loss and the most recurrent hemizygous deletion involved the B3GAT1 gene on chromosome11q25. Focal gains on 11q13.3 in 37% of cases (19/51), consistently involved CTTN and SHANK2 genes. Twelve of these cases (23,5%), had a broader region of gain that also included the CCND1, FGF19, FGF4 and FGF3 genes. SHANK2 and CTTN are co-amplified in several cancers, these proteins interact functionally together and are involved in cell motility. Immunohistochemistry confirmed both Shank2 (79%) and cortactin (69%) protein overexpression in samples with gains of these genes. In contrast, cyclin D1 (65%) was moderately expressed in samples with CCND1 DNA gain. This study reports copy number changes in a South African ESCC cohort and highlights similarities and differences with cohorts from Asia and Malawi. Our results strongly suggest a role for CTTN and SHANK2 in the pathogenesis of ESCC in South Africa.
Project description:If copy number variants (CNVs) are predominantly deleterious, we would expect them to be more efficiently purged from populations with a large effective population size (Ne) than from populations with a small Ne. Malaria parasites (Plasmodium falciparum) provide an excellent organism to examine this prediction, because this protozoan shows a broad spectrum of population structures within a single species, with large, stable, outbred populations in Africa, small unstable inbred populations in South America and with intermediate population characteristics in South East Asia. We characterized 122 single-clone parasites, without prior laboratory culture, from malaria-infected patients in 7 countries in Africa, SE Asia and S. America using a high density SNP/CNV microarray. We scored 134 high-confidence CNVs across the parasite exome, including 33 deletions and 102 amplifications, which ranged in size from <500bp to 59kb, as well as 10,107 flanking, biallelic SNPs. Overall, CNVs were rare, small and skewed towards low frequency variants, consistent with the deleterious model. Relative to African and SE Asian populations, CNVs were significantly more common in S. America, showed significantly less skew in allele frequencies, and were significantly larger. On this background of low frequency CNV, we also identified several high-frequency CNVs under putative positive selection using an FST outlier analysis. These included known adaptive CNVs containing rh2b and pfmdr1, and several other CNVs (e.g. DNA helicase, and 3 conserved proteins) that require further investigation. Our data are consistent with a significant impact of genetic structure on CNV burden in an important human pathogen.
Project description:In the present study, endogenous cysteine S-nitrosation site and S-nitrosated proteins were identified by iodo-TMT labeling during somatic embryogenesis in Brazilian pine, an endangered native conifer of South America.
Project description:If copy number variants (CNVs) are predominantly deleterious, we would expect them to be more efficiently purged from populations with a large effective population size (Ne) than from populations with a small Ne. Malaria parasites (Plasmodium falciparum) provide an excellent organism to examine this prediction, because this protozoan shows a broad spectrum of population structures within a single species, with large, stable, outbred populations in Africa, small unstable inbred populations in South America and with intermediate population characteristics in South East Asia. We characterized 122 single-clone parasites, without prior laboratory culture, from malaria-infected patients in 7 countries in Africa, SE Asia and S. America using a high density SNP/CNV microarray. We scored 134 high-confidence CNVs across the parasite exome, including 33 deletions and 102 amplifications, which ranged in size from <500bp to 59kb, as well as 10,107 flanking, biallelic SNPs. Overall, CNVs were rare, small and skewed towards low frequency variants, consistent with the deleterious model. Relative to African and SE Asian populations, CNVs were significantly more common in S. America, showed significantly less skew in allele frequencies, and were significantly larger. On this background of low frequency CNV, we also identified several high-frequency CNVs under putative positive selection using an FST outlier analysis. These included known adaptive CNVs containing rh2b and pfmdr1, and several other CNVs (e.g. DNA helicase, and 3 conserved proteins) that require further investigation. Our data are consistent with a significant impact of genetic structure on CNV burden in an important human pathogen. SNP/CGH hybridisation of 175 malaria parasite samples
Project description:The principal objective of this work was to investigate the somatic copy number changes that influence the risk of head and neck cancer occurrence and outcome from two large comprehensive case series in Europe and South America. A second objective was to investigate how these somatic changes interact with environmental and host risk factors such including HPV infection, alcohol and smoking.
Project description:Recent outbreaks of Zika virus (ZIKV) in South and Central America have highlighted significant neurological side effects. Concurrence with the inflammatory neuropathy Guillain-Barré syndrome (GBS) is observed in 1:4000 ZIKV cases. Whether the neurological symptoms of ZIKV infection are a consequence of autoimmunity or direct neurotoxicity is unclear.
Project description:This phase 2, randomized, active-controlled, open-label, parallel group, multicenter study will be conducted at up to 18 study centers in the US, Central America, and South America. Adult subjects with metastatic colorectal cancer (CRC) who failed first-line chemotherapy will participate in the study, which will be conducted on an outpatient basis. It is anticipated that 100 subjects will be enrolled to obtain approximately 90 evaluable subjects.
Project description:Coccidioidomycosis, or Valley Fever, is a lung disease caused by inhaling Coccidioides fungi, prevalent in the Southwestern U.S., Mexico, and parts of Central and South America. Climate change is contributing to the spread of this disease. Many cases are asymptomatic, some are often misdiagnosed, and a small subset can progress to severe illness. To better understand lung responses during late Coccidioides infection, we used 10x Visium spatial transcriptomics. We analyzed non-infected lung (D0) and infected lung at 14 days post-infection (D14).