RESUMO
Woolly mammoths in mainland Alaska overlapped with the region's first people for at least a millennium. However, it is unclear how mammoths used the space shared with people. Here, we use detailed isotopic analyses of a female mammoth tusk found in a 14,000-year-old archaeological site to show that she moved ~1000 kilometers from northwestern Canada to inhabit an area with the highest density of early archaeological sites in interior Alaska until her death. DNA from the tusk and other local contemporaneous archaeological mammoth remains revealed that multiple mammoth herds congregated in this region. Early Alaskans seem to have structured their settlements partly based on mammoth prevalence and made use of mammoths for raw materials and likely food.
Assuntos
Mamutes , Humanos , Animais , Feminino , Recém-Nascido , Mamutes/genética , DNA , Canadá , Alaska , FósseisRESUMO
Polyploidization is an important mechanism for introducing diversity into a population and promoting evolutionary change. It is believed that most, if not all, angiosperms have undergone whole genome duplication events in their evolutionary history, which has led to changes in genome structure, gene regulation, and chromosome maintenance. Previous studies have shown that polyploidy can coincide with meiotic abnormalities and somatic cytogenetic mosaics in Arabidopsis allotetraploids, but it is unclear whether this phenomenon can contribute to novel diversity or act as a mechanism for speciation. In this study we tested the hypothesis that mosaic aneuploidy contributes to the formation of incipient diversity in neoallopolyploids. We generated a population of synthesized Arabidopsis allohexaploids and monitored karyotypic and phenotypic variation in this population over the first seven generations. We found evidence of sibling line-specific chromosome number variations and rapidly diverging phenotypes between lines, including flowering time, leaf shape, and pollen viability. Karyotypes varied between sibling lines and between cells within the same tissues. Cytotypic variation correlates with phenotypic novelty, and, unlike in allotetraploids, remains a major genomic destabilizing factor for at least the first seven generations. While it is still unclear whether new stable aneuploid lines will arise from these populations, our data are consistent with the notion that somatic aneuploidy, especially in higher level allopolyploids, can act as an evolutionary relevant mechanism to induce rapid variation not only during the initial allopolyploidization process but also for several subsequent generations. This process may lay the genetic foundation for multiple, rather than just a single, new species.
Assuntos
Arabidopsis/genética , Evolução Biológica , Poliploidia , Aneuploidia , Biodiversidade , Cromossomos de Plantas , Genoma de Planta , Instabilidade Genômica , Mitose , Fenótipo , Pólen/metabolismoRESUMO
A preliminary study was conducted with sisomicin, a new aminoglycoside antibiotic. The drug was administered to 40 patients in doses varying from 1.5 to 3.75 mg/kg/day. Sisomicin proved to be an effective therapy in urinary tract infections and to a lesser extent in wound infections caused by gram-negative rods; favorable results have been observed in 91.6% and in 66.6% of the patients presenting these infections. Toxic reactions involving the hearing function, renal function, and general tolerance were infrequent: they occurred in less than 5% of the patients in this series. (However in approximately 22% of the patients, there was a transient appearance of granular casts in the urine.