The end of the Kachemak tradition on the Kenai Peninsula, southcentral Alaska

The Kachemak tradition was established by ca. 3000 B.P. in Kachemak Bay. Probably somewhat later a variant termed Riverine Kachemak, with a population adapted to salmon and terrestrial resources, appeared on the northern Kenai Peninsula. The Kachemak tradition people seem to have abandoned Kachemak Bay by ca. 1400 B.P. Seven of 12 available Kachemak tradition dates predate 1400 B.P. even at two sigma. Scattered younger dates are thus suspect outliers. The end of Riverine Kachemak tradition has been placed at ca. 1000 B.P., at which time the population was supposedly replaced by in-migrating groups ancestral to the Dena'ina Athapaskans. Close examination of the numerous available radiocarbon dates shows that most Riverine Kachemak dates cluster in the early centuries of the First Millennium A.D. and most Dena'ina dates substantially postdate 1000 A.D. Probably the Riverine Kachemak and Dena'ina peoples never met on the Kenai River. However, the correspondence in date ranges between Kachemak Bay and Riverine Kachemak is striking, suggesting their fates were linked. Both traditions collapsed by 1400-1500 B.P. The causes are probably multiple but do not include cultural replacement.     

Immune challenge retards seasonal reproductive regression in rodents: evidence for terminal investment

Animals must balance investments in different physiological activities to allow them to maximize fitness in the environments they inhabit. These adjustments among reproduction, growth and survival are mandated because of the competing high costs of each process. Seasonally breeding rodents generally bias their investments towards reproduction when environmental conditions are benign, but shift these investments towards processes that promote survival, including immune activity, when environmental conditions deteriorate. Because survival probability of non-tropical small mammals is generally low in winter, under certain circumstances, these animals may not allocate resources to survival mechanisms in an effort to produce as many offspring as possible in the face of increased probability of death. Such 'terminal investments' have been described in passerines, but there are few examples of such phenomena in small mammals. Here, we show that male Siberian hamsters (Phodopus sungorus) challenged with lipopolysaccharide (a component of gram-negative bacteria that activates the immune system) induced a small, but significant, retardation of seasonal regression of the reproductive system relative to saline-injected hamsters. This delayed reproductive regression likely reflects a strategy to maintain reproductive function when survival prospects are compromised by infection.     

Generation of T-cell receptor retrogenic mice

T-cell receptor (TCR) transgenic (Tg) mice have revolutionized our understanding of many aspects of T-cell biology. Whereas they provide an almost unlimited source of T cells with a single specificity, breeding them onto different backgrounds and/or new knockout/knock-in mouse models is often time-consuming (6 months to several years), which can make the process costly and can significantly delay research. This protocol describes a new method for expressing defined TCR-alpha and TCR-beta proteins from a single 2A peptide-linked multicistronic retroviral vector in mice, using retrovirus-mediated stem cell gene transfer. We refer to these as 'retrogenic' (Rg) mice ('retro' from retrovirus and 'genic' from Tg) to avoid confusion with traditional transgenic mice. We have successfully used this approach to express over 50 different TCRs on several different mouse backgrounds in as little as 6 weeks.     

Analyzing chromatin remodeling complexes using shotgun proteomics and normalized spectral abundance factors

Mass spectrometry-based approaches are commonly used to identify proteins from multiprotein complexes, typically with the goal of identifying new complex members or identifying post-translational modifications. However, with the recent demonstration that spectral counting is a powerful quantitative proteomic approach, the analysis of multiprotein complexes by mass spectrometry can be reconsidered in certain cases. Using the chromatography-based approach named multidimensional protein identification technology, multiprotein complexes may be analyzed quantitatively using the normalized spectral abundance factor that allows comparison of multiple independent analyses of samples. This study describes an approach to visualize multiprotein complex datasets that provides structure function information that is superior to tabular lists of data. In this method review, we describe a reanalysis of the Rpd3/Sin3 small and large histone deacetylase complexes previously described in a tabular form to demonstrate the normalized spectral abundance factor approach.