The skeletal biology of the Virginia Indians

Statistical analysis of one eastern and two western Virginia Indian skeletal samples reveals a general association between geographical and biological distance. However, the data suggest the importance of gene flow as a factor in minimizing local microdifferentiation. Females appear to contribute a disproportionate share to gene flow. This may be attributed to the widespread and apparently frequent practice of acquiring females and children through capture during recurring warfare.     

Biophysical studies of cholesterol effects on chromatin

Changes in chromatin structure regulate gene expression and genome maintenance. Molecules that bind to the nucleosome, the complex of DNA and histone proteins, are key modulators of chromatin structure. Previous work indicated that cholesterol, a ubiquitous cellular lipid, may bind to chromatin in vivo, suggesting a potential function for lipids in modulating chromatin architecture. However, the molecular mechanisms of cholesterol's action on chromatin structure have remained unclear. Here, we explored the biophysical impact of cholesterol on nucleosome and chromatin fibers reconstituted in vitro and characterized in silico the cholesterol binding to the nucleosome. Our findings support that cholesterol assists 10 and 30 nm chromatin formation and induces folding of long chromatin fibers as a result of direct interaction of the cholesterol to six nucleosomal binding sites.     

Ideas in theoretical biology

The potential and realized impact of Bohm's views on biology are briefly discussed.     

An Improved Boosting to Amplify Signal with Isobaric Labeling (iBASIL) Strategy for Precise Quantitative Single-cell Proteomics

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Highlights

• •Higher AGC significantly improves quantitation quality in single-cell analysis.
• •The boosting-to-sample ratio should be carefully evaluated and optimized.
• •iBASIL allows for precise quantitation of 1,500 proteins from 104 AML single cells.
• •iBASIL recapitulates major biological differences in different AML single cells.

     

The sweet jelly of Combretum lanceolatum flowers (Combretaceae): a cornucopia resource for bird pollinators in the Pantanal, western Brazil

 The pollination biology of the neotropical scandent shrub Combretum lanceolatum was studied in the seasonally-flooded Pantanal region in western Brazil. This plant bears horizontally oriented inflorescences, whose yellowish green flowers begin to expand at dusk and are fully open at dawn. Instead of fluid nectar the flowers produce sweet gelatinous secretion in form of pellets. The glandular complex of the flower is composed of the inner wall of the receptacle and its tubular extension, being equivalent to the nectariferous disk of the nectar-producing species within the genus. The jelly is produced at night, contains mannan and is imbibed by free hexoses. It originates by swelling and disintegration of the inner wall, after contact with the nectar generated concomitantly in the mesophyll. Combretum lanceolatum is unique within the genus in its production of jelly pellets instead of liquid nectar. A new term, the jelly-flower, is proposed for flowers with this kind of reward. The pellet is not replaced once removed by a bird, and thus resembles a fruit in its availability to consumers, another unique feature that distinguishes this species within the genus. The jelly pellets offered by the many flowered branches attract a great diversity of bird visitors (28 species from eight families), which feed on this copious food resource and pollinate the flowers. The most effective pollinators probably are thrushes, tanagers, and orioles. Flocking parakeets and macaws sometimes feed on the petals, thus acting as flower plunderers. Combretum lanceolatum presents a high fruit set under natural conditions, which likely favours its spreading and becoming a weed species. Received July 11, 2000 Accepted November 18, 2000     

From trickle to flood: the large-scale,cryptic invasion of California by tropical fruit flies

Since 1954, when the first tropical tephritid fruit fly was detected in California, a total of 17 species in four genera and 11 386 individuals (adults/larvae) have been detected in the state at more than 3348 locations in 330 cities. We conclude from spatial mapping analyses of historical capture patterns and modelling that, despite the 250+ emergency eradication projects that have been directed against these pests by state and federal agencies, a minimum of five and as many as nine or more tephritid species are established and widespread, including the Mediterranean, Mexican and oriental fruit flies, and possibly the peach, guava and melon fruit flies. We outline and discuss the evidence for our conclusions, with particular attention to the incremental, chronic and insidious nature of the invasion, which involves ultra-small, barely detectable populations. We finish by considering the implications of our results for invasion biology and for science-based invasion policy.     

Meaning in Nature: Organic Manufacture?

The paper examines Marcello Barbieri’s (2007) Introduction to Biosemiotics. Highlighting debate within the biosemiotic community, it focuses on what the volume offers to those who explain human intellect in relation to what Turing called our ‘physical powers.’ In scrutinising the basis of world-modelling, parallels and contrasts are drawn with other work on embodied-embedded cognition. Models dominate biology. Is this a qualitative fact or does it point to biomechanisms? In evaluating the 18 contributions, it is suggested that the answers will shape the field. First, they will decide if biochemistry and explanatory reduction can be synergised by biosemantics. Second, they will show if our intellectual powers arise from biology. Does thinking use—not a language faculty—but what Marko? and colleagues call semiosis by the living? Resolution of such issues, it is suggested, can change how we view cognition. Above all, if the biomechanists win the day, cultural models can be regarded as extending natural meaning. On such a view, biomechanisms prompt us to act and perceive as we model our own natural models. This fits Craik’s vision: intellect gives us the alphanumerical ‘symbols’ that allow thoughts to have objective validity. For the biomechanist, this is explained—not by brains alone—but, rather, by acting under the constraints of historically extended sensoria.     

Reproduction of the rare monocarpic species Saxifraga mutata L.

The aim of the study is to investigate the impact of reproduction and genetic variation on the persistence of populations of the prealpine, monocarpic Saxifraga mutata L. The species grows on erosion slopes or rocks, and its local populations are often small and isolated. Crossing experiments resulted in better seed-set than selfing, but both yielded viable seeds. Agamospermy did not occur. In an early-successional species like S. mutata , successful selfing is important in the colonization of new habitats. Flowers of S. mutata were visited by Syrphidae and unspecialized Hymenoptera. A germination rate of 40% was reached in cultivation after 20 weeks but germination continued until the end of the experiment after 92 weeks. Seeds stored dry for 30 months at room temperature mostly lost their germinability. In natural habitats, seedlings were found almost throughout the year with a peak in spring. Suitable safe sites were small patches of open soil, bare marl on erosion slopes, and rock crevices. AU individuals investigated were diploid with 2n = 26. Allozyme electrophoresis showed a lack of segregation within the populations. Intra- and interpopulation genetic variation was low. These results were in partial disagreement with theoretical expectations in a mixed mating species. It is concluded that demographic rather than genetic processes are the main cause of extinction of populations of S. mutata , at least in the short-term.