Reconstructing Native American Population History

The peopling of the Americas has been the subject of extensive genetic, archaeological and linguistic research; however, central questions remain unresolved1–5. One contentious issue is whether the settlement occurred via a single6–8 or multiple streams of migration from Siberia9–15. The pattern of dispersals within the Americas is also poorly understood. To address these questions at higher resolution than was previously possible, we assembled data from 52 Native American and 17 Siberian groups genotyped at 364,470 single nucleotide polymorphisms. We show that Native Americans descend from at least three streams of Asian gene flow. Most descend entirely from a single ancestral population that we call “First American”. However, speakers of Eskimo-Aleut languages from the Arctic inherit almost half their ancestry from a second stream of Asian gene flow, and the Na-Dene-speaking Chipewyan from Canada inherit roughly one-tenth of their ancestry from a third stream. We show that the initial peopling followed a southward expansion facilitated by the coast, with sequential population splits and little gene flow after divergence, especially in South America. A major exception is in Chibchan-speakers on both sides of the Panama Isthmus, who have ancestry from both North and South America

The protective effect of the Vacha rhizome extract on chronic stress-induced immunodeficiency in rat

Context: Chronic stress is an inevitable factor in the modern day society which affects cell mediated as well as humoral immunity. There is a need to prevent stress effects with traditionally used herbs. Objective: The present study was undertaken to investigate the immunoprotective effect of Vacha (Acorus calamus L. Acoraceae) rhizome under stressful condition. Materials and methods: Soxlet extraction of Vacha rhizome was performed with increasing polarity of solvents, i.e., petroleum ether to ethanol. The extract was concentrated by distilling off the solvent in flash evaporator and dried in desiccators. The benzene extract was found to have anti-stress property in our earlier studies and hence it was used in the present experiment. Extract was administered every day for 4 weeks orally to adult female rats prior to exposure to stress, restraint (1 h) and forced swimming exercise (15 min). Results: Vacha rhizome extract significantly prevented the stress induced reduction in total and differential leukocytes count, immunoglobulin content, bone marrow cellularity and viability, lymphocytes counts in lymphoid organs, islands of white pulp of spleen (ED50 = 10 mg, p < 0.001) and a significant increase in circulating immune complexes and apoptotic index of lymphoid organs (ED50 = 10 mg, p < 0.001) compared to controls. Discussion and conclusion: The present study clearly indicates that Vacha extract not only prevents stress-induced suppression of immunity and structural involution of lymphoid organs, but also boosts immunity in normal rats. Therefore, it is suggested that Vacha extract administration maintains normal immunity despite the body experiencing stress

Genetic determinants of swarming in Rhizobium etli.

Swarming motility is considered to be a social phenomenon that enables groups of bacteria to move coordinately atop solid surfaces. The differentiated swarmer cell population is embedded in an extracellular slime layer, and the phenomenon has previously been linked with biofilm formation and virulence. The gram-negative nitrogen-fixing soil bacterium Rhizobium etli CNPAF512 was previously shown to display swarming behavior on soft agar plates. In a search for novel genetic determinants of swarming, a detailed analysis of the swarming behavior of 700 miniTn5 mutants of R. etli was performed. Twenty-four mutants defective in swarming or displaying abnormal swarming patterns were identified and could be divided into three groups based on their swarming pattern. Fourteen mutants were completely swarming deficient, five mutants showed an atypical swarming pattern with no completely smooth edge and local extrusions, and five mutants displayed an intermediate swarming phenotype. Sequence analysis of the targeted genes indicated that the mutants were likely affected in quorum-sensing, polysaccharide composition or export, motility, and amino acid and polyamines metabolism. Several of the identified mutants displayed a reduced symbiotic nitrogen fixation activity.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Racial and Ethnic Diagnostic Patterns in Schizophrenia Spectrum Disorders

The literature on racial and ethnic diagnostic patterns (as these pertain to schizophrenia spectrum disorders) is reviewed in this chapter. The chapter begins with a review of the literature on the diagnostic patterns among racial and ethnic minorities in the USA and abroad, followed by a review of racial/ethnic differences in symptom severity, symptom expression, and prevalence rates. This is then followed by a review of the empirical literature that offers explanations about why differential diagnostic patterns are observed. This review explores the question of whether differential patterns are due to inherent differences between racial/ethnic groups or if clinician biases and/or decision-making processes are contributing to differential diagnostic practices. Finally, literature that points to cultural mistrust, paranoia, and other environmental factors (e.g., stress) as potential variables that may contribute to the differential diagnostic patterns among racial/ethnic groups is reviewed. These reviews suggest that Black patients are three to four times more likely to receive a schizophrenia spectrum diagnosis. Findings also suggest that racial/ethnic variations may exist on a symptom level, with greater differences observed among positive symptom profiles. This review suggests that unawareness of cultural differences in symptom expression, cultural mistrust, and environmental factors (e.g., low SES) may be related to greater likelihood of receiving a schizophrenia spectrum diagnosis but do not fully account for the diagnostic discrepancies observed among racial/ethnic groups. To better understand these relationships, we conclude with recommendations to improve diagnostic accuracy and cultural competence (e.g., greater reliance on the Cultural Formulation Interview) and suggestions for future research that may further clarify the racial/ethnic diagnostic conundrum (e.g., using analog research studies)