Patterns of Stem Cell Divisions Contribute to Plant Longevity

The lifespan of plants ranges from a few weeks in annuals to thousands of years in trees. It is hard to explain such extreme longevity considering that DNA replication errors inevitably cause mutations. Without purging through meiotic recombination, the accumulation of somatic mutations will eventually result in mutational meltdown, a phenomenon known as Muller’s ratchet. Nevertheless, the lifespan of trees is limited more often by incidental disease or structural damage than by genetic aging. The key determinants of tree architecture are the axillary meristems, which form in the axils of leaves and grow out to form branches. The number of branches is low in annual plants, but in perennial plants iterative branching can result in thousands of terminal branches. Here, we use stem cell ablation and quantitative cell-lineage analysis to show that axillary meristems are set aside early, analogous to the metazoan germline. While neighboring cells divide vigorously, axillary meristem precursors maintain a quiescent state, with only 7–9 cell divisions occurring between the apical and axillary meristem. During iterative branching, the number of branches increases exponentially, while the number of cell divisions increases linearly. Moreover, computational modeling shows that stem cell arrangement and positioning of axillary meristems distribute somatic mutations around the main shoot, preventing their fixation and maximizing genetic heterogeneity. These features slow down Muller’s ratchet and thereby extend lifespan.

87Sr/86Sr ratios of middle Miocene to Pleistocene planktonic foraminifers from ODP Site 117-722 (Table 3)

Continuous magnetostratigraphy and biostratigraphy made it possible to construct a detailed late Neogene record of 87Sr/86Sr isotopic ratios of ocean water, as measured in the tests of planktonic foraminifers. Sediments recovered during Leg 117, in the western Arabian Sea, provide a continuous, high resolution sedimentary record from the early Miocene to present. The late Miocene to Recent is marked by rapidly increasing 87Sr/86Sr ratios in seawater, which results in a chronostratigraphical resolution varying from 0.2 Ma to 1.5 Ma. The 87Sr/86Sr seawater curve has a stepwise character similar to the one determined by DePaolo on Site 590B, in the Tasman Sea, and to the one determined by McKenzie on Site 653A, in the Mediterranean, confirming its use as a chronostratigraphic tool for this time span. Periods of rapid increase in the 87Sr/86Sr isotopic ratio of seawater are correlated with important changes in tectonic and climatic conditions. Experiments showed that bulk carbonate sediment samples have differing 87Sr/86Sr ratios from those of planktonic and benthic foraminifers from the same depth.

Archaeological sites in China during the Neolithic and Bronze Age

A total of 51,074 archaeological sites from the early Neolithic to the early Iron Age (c. 8000-500 BC), with a spatial extent covering most regions of China (c. 73-131°E and c. 20-53°N), were analysed over space and time in this study. Site maps of 25 Chinese provinces, autonomous regions and municipalities, published in the series 'Atlas of Chinese Cultural Relics', were used to extract, digitalise and correlate its archaeological data. The data were, in turn, entered into a database using a self-developed mapping software that makes the data, in a dynamic way, analysable as a contribution to various scientific questions, such as population growth and migrations, spread of agriculture and changes in subsistence strategies. The results clearly show asynchronous patterns of changes between the northern and southern parts of China (i.e. north and south of the Yangtze River, respectively) but also within these macro-regions. In the northern part of China (i.e. along the Yellow River and its tributaries and in the Xiliao River basin), the first noticeable increase in the concentration of Neolithic sites occurred between c. 5000 and 4000 BC; however, highest site concentrations were reached between c. 2000 and 500 BC. Our analysis shows a radical north-eastern shift of high site-density clusters (over 50 sites per 100 * 100 km grid cell) from the Wei and middle/lower Yellow Rivers to the Liao River system sometime between 2350 BC and 1750 BC. This shift is hypothetically discussed in the context of the incorporation of West Asian domesticated animals and plants into the existing northern Chinese agricultural system. In the southern part of China, archaeological sites do not show a noticeable increase in the absolute number of sites until after c. 1500 BC, reaching a maximum around 1000 BC.

Theologiae R.P. Fr. Suarez e Societate Jesu, summa, seu compendium /

Table of contents at end of each volume.

D. Martin Luthers Werke.

This book is a pre-publication prospectus of the Weimar Edition of Luther's Works. It contains a table of contents as well as the anticipated publication date for each forthcoming volume. As they are printed, each volume of Luther's works will be divided into four "series": I: Werke; II: Tischreden; III: Deutsche Bibel; IV: Briefe.

The roll of the Royal College of Physicians of London : comprising biographical sketches of all the eminent physicians whose names are recorded in the Annals from the foundation of the college in 1518 to its removal in 1825, from Warwick Lane to Pall Mall East /

Includes indexes.

An ecclesiastical history, ancient and modern : from the birth of Christ to the beginning of the eighteenth century /

Chronological tables and indexes in v. 6.

The Turnament of Totenham and the Feest. Two early ballads printed from a manuscript preserved in the public library of the University of Cambridge.

Edited by Thomas Wright. Ascribed in early editions to Gilbert Pilkington, who was probably only the transcriber of part of the manuscript. cf. Camb. univ. Cat. of mss., v. 2, p. 505, and Dict. nat. biog.

A topographical and historical description of the county of York; containing an account of its towns, cathedral, castles, antiquities, churches, monuments, public edifices, picturesque scenery, the residences of the nobility, gentry, &c. accompanied with biographical notices of eminent and learned men to whom this county has given birth.

A separate issue, with new t.-p., of a part of v. 16 of The beauties of England and Wales.

The history of Fairfield, Fairfield County, Connecticut, from the settlement of the town in 1639 to 1818,

No more published.

An universal history : from the earliest accounts to the present time /

Articles by George Sale, George Psalmanazar, Archibald Bower, George Shelvocke, John Campbell, John Swinton, and others, cf. Brit.mus. Catalogue.

An index to the wills and inventories now preserved in the Probate registry, at Chester ...

Report of the Record Society for the year 1896/97 contained in v. 1, 1897/98 in v. 2.

A history of the French novel (to the close of the 19th century) /

Includes "bibliographical notes" (vol. 1, p. 479-482) and index.

Admissions to Trinity College, Cambridge ...

"Members of Kings's hall" by A.E. Stamp: v. 1, p. [79]-140.

Histoire naturelle de l'ame /

Includes "Lettre critique de Mr. de la Mettrie sur L'histoire naturelle de l'ame. A madame la marquise du Chatelet," 12 pages at the end.