The prehistoric peopling of Southeast Asia

The human occupation history of Southeast Asia (SEA) remains heavily debated. Current evidence suggests that SEA was occupied by Hòabìnhian hunter-gatherers until ~4000 years ago, when farming economies developed and expanded, restricting foraging groups to remote habitats. Some argue that agricultural development was indigenous; others favor the “two-layer” hypothesis that posits a southward expansion of farmers giving rise to present-day Southeast Asian genetic diversity. By sequencing 26 ancient human genomes (25 from SEA, 1 Japanese Jōmon), we show that neither interpretation fits the complexity of Southeast Asian history: Both Hòabìnhian hunter-gatherers and East Asian farmers contributed to current Southeast Asian diversity, with further migrations affecting island SEA and Vietnam. Our results help resolve one of the long-standing controversies in Southeast Asian prehistory.

Ancient genomes document multiple waves of migration in Southeast Asian prehistory

Southeast Asia is home to rich human genetic and linguistic diversity, but the details of past population movements in the region are not well known. Here, we report genome-wide ancient DNA data from 18 Southeast Asian individuals spanning from the Neolithic period through the Iron Age (4100 to 1700 years ago). Early farmers from Man Bac in Vietnam exhibit a mixture of East Asian (southern Chinese agriculturalist) and deeply diverged eastern Eurasian (hunter-gatherer) ancestry characteristic of Austroasiatic speakers, with similar ancestry as far south as Indonesia providing evidence for an expansive initial spread of Austroasiatic languages. By the Bronze Age, in a parallel pattern to Europe, sites in Vietnam and Myanmar show close connections to present-day majority groups, reflecting substantial additional influxes of migrants.

Increased level of immunogold labeling of epoxy sections by rising the temperature significantly beyond 100 degrees C in the antigen retrieval medium

The purpose of this study was to compare the level of immunogold labeling of epoxy sections when the sections were subjected to antigen retrieval at different temperatures. Renal swine tissue with glomerular immune complex deposits with reactivity against IgG and C3 was embedded in epoxy resin. Sections from these blocks were exposed to antigen retrieval by heating in citrate solution at temperatures in the range of 25-135 degrees C. Immunogold labeling with anti-IgG and anti-C3 was performed on the heated sections. The level of immunogold labeling increased significantly in the direction of increased heat. Interestingly, the level of immunogold labeling was significantly higher when exposed to heating in the autoclave (121 and 135 degrees C) than at temperatures just below the normal boiling point. Sections stained with anti-C3 turned from almost negative labeling when heated at 95 degrees C to strong positive labeling when heated at 135 degrees C (11 times increased). The intensity of the immunogold labeling with anti-IgG increased almost three times when raising the temperature in the retrieval medium from 95 to 135 degrees C. The practical significance of these results is that antigen retrieval of epoxy sections should be performed by heating in aqueous solutions at 135 degrees C or higher to obtain maximum immunolabeling.