The [(G/C)3NN]n motif: a common DNA repeat that excludes nucleosomes.

Nucleosomes, the basic structural elements of chromosomes, consist of 146 bp of DNA coiled around an octamer of histone proteins, and their presence can strongly influence gene expression. Considerations of the anisotropic flexibility of nucleotide triplets containing 3 cytosines or guanines suggested that a [5'(G/C)3 NN3']n motif might resist wrapping around a histone octamer. To test this, DNAs were constructed containing a 5'-CCGNN-3' pentanucleotide repeat with the Ns varied. Using in vitro nucleosome reconstitution and electron microscopy, a plasmid with 48 contiguous CCGNN repeats strongly excluded nucleosomes in the repeat region. Competitive reconstitution gel retardation experiments using DNA fragments containing 12, 24, or 48 CCGNN repeats showed that the propensity to exclude nucleosomes increased with the length of the repeat. Analysis showed that a 268-bp DNA containing a (CCGNN)48 block is 4.9 +/- 0.6-fold less efficient in nucleosome assembly than a similar length pUC19 fragment and approximately 78-fold less efficient than a similar length (CTG)n sequence, based on results from previous studies. Computer searches against the GenBank database for matches with a [(G/C)3NN]48 sequence revealed numerous examples that frequently were present in the control regions of "TATA-less" genes, including the human ETS-2 and human dihydrofolate reductase genes. In both cases the (G/C)3NN repeat, present in the promoter region, co-maps with loci previously shown to be nuclease hypersensitive sites.

The adipocyte specific transcription factor C/EBPalpha modulates human ob gene expression.

The ob gene product, leptin, apparently exclusively expressed in adipose tissue, is a signaling factor regulating body weight homeostasis and energy balance. ob gene expression is increased in obese rodents and regulated by feeding, insulin, and glucocorticoids, which supports the concept that ob gene expression is under hormonal control, which is expected for a key factor controlling body weight homeostasis and energy balance. In humans, ob mRNA expression is increased in gross obesity; however, the effects of the above factors on human ob expression are unknown. We describe the structure of the human ob gene and initial functional analysis of its promoter. The human ob gene's three exons cover approximately 15 kb of genomic DNA. The entire coding region is contained in exons 2 and 3, which are separated by a 2-kb intron. The first small 30-bp untranslated exon is located >10.5 kb upstream of the initiator ATG codon. Three kilobases of DNA upstream of the transcription start site has been cloned and characterized. Only 217 bp of 5' sequence are required for basal adipose tissue-specific expression of the ob gene as well as enhanced expression by C/EBPalpha. Mutation of the single C/EBPalpha site in this region abolished inducibility of the promoter by C/EBPalpha in cotransfection assays. The gene structure will facilitate our analysis of ob mutations in human obesity, whereas knowledge of sequence elements and factors regulating ob gene expression should be of major importance in the prevention and treatment of obesity.

ndhF sequence evolution and the major clades in the sunflower family.

An extensive sequence comparison of the chloroplast ndhF gene from all major clades of the largest flowering plant family (Asteraceae) shows that this gene provides approximately 3 times more phylogenetic information than rbcL. This is because it is substantially longer and evolves twice as fast. The 5' region (1380 bp) of ndhF is very different from the 3' region (855 bp) and is similar to rbcL in both the rate and the pattern of sequence change. The 3' region is more A+T-rich, has higher levels of nonsynonymous base substitution, and shows greater transversion bias at all codon positions. These differences probably reflect different functional constraints on the 5' and 3' regions of ndhF. The two patterns of base substitutions of ndhF are particularly advantageous for phylogenetic reconstruction because the conserved and variable segments can be used for older and recent groups, respectively. Phylogenetic analyses of 94 ndhF sequences provided much better resolution of relationships than previous molecular and morphological phylogenies of the Asteraceae. The ndhF tree identified five major clades: (i) the Calyceraceae is the sister family of Asteraceae; (ii) the Barnadesioideae is monophyletic and is the sister group to the rest of the family; (iii) the Cichorioideae and its two basal tribes Mutisieae and Cardueae are paraphyletic; (iv) four tribes of Cichorioideae (Lactuceae, Arctoteae, Liabeae, and Vernonieae) form a monophyletic group, and these are the sister clade of the Asteroideae; and (v) the Asteroideae is monophyletic and includes three major clades.

Compendium physicæ ex authoribus extractum, 1714

Manuscript copy of Charles Morton’s Compendium Physicae prepared by copyist Robert Ward in 1714. The leather-bound volume includes text and drawings, and there is an index to the chapters of the book at the end of the volume. "Thomas Greaves's book Octob 1 Anno Salutis 1714" inscribed on flyleaf. Thomas Greaves may refer to the Charlestown physician and judge and member of the Harvard Class of 1703.

Nantucket Shoals, Massachusetts, 1786 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: A pilot's chart of Nantukket Shoals, by Captn. Thomas Jones, Jnr., of Falmouth in the county of Barnsable, Apr. 7, 1786. Scale [ca. 1:219,400]. Covers Nantucket Sound, Massachusetts and surrounding land. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Massachusetts State Plane Coordinate System, Mainland Zone (in Feet) (Fipszone 2001). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. This nautical chart shows coastal features such as lighthouses, rocks, shoals, currents, channels, points, coves, harbors, islands, and more. Depths are shown by soundings and shading. Land features include settlements, wind mills, and more. This layer is part of a selection of digitally scanned and georeferenced historic maps of Massachusetts from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of regions, originators, ground condition dates (1755-1922), scales, and purposes. The digitized selection includes maps of: the state, Massachusetts counties, town surveys, coastal features, real property, parks, cemeteries, railroads, roads, public works projects, etc.

Porosity and sound velocity measured in sediment core CIROS-1

The CIROS-1 drillhole, which in 1986 reached a depth of 700 m below the seafloor, is still the only deep hole that can provide information on the velocity structure of the upper crust in McMurdo Sound and the Ross Sea, Antarctica. A careful review and quality control of the downhole logging data of CIROS-1 resulted in a new porosity depth function that is consistent with porosity data from the MSSTS-1 and CRP-1 drillholes. Using existing porosity-velocity equations, it was possible for the first time to obtain reliable velocity information for the upper 700 m of strata off the Victoria Land coast. The calculated synthetic seismograms, based on downhole velocity and density data, fit very well with the existing seismic lines IT90A-71, PD90-12, and NBP9601-89. The quality of the correlation confirms that the average velocity of the top 700 m of strata is about 2 000-2 300 m/s, and not 2 800-3 000 m/s, as was previously assumed. In consequence, these distinctly lower velocities result in shallower depths for the seismic unconformities V3/V4 andV4/V5 and thus may have important implications for further drilling off Cape Roberts.

Pamphlets - homoeopathic.

Title from spine.

Latest contemporary portraits,

"Second printing, April, 1928."

Cheechako into sourdough,

Mode of access: Internet.

Latest contemporary portraits,

David Graham Phillips: the greatest American novelist.--Eleonora Duse.--Henri Barbusse.--Lord Bryce.--George Russell (A.E.)--Mrs. Humphry Ward.--Eugene V. Debs.--Charles Schwab: the master of Bethlehem.--Prince Peter Kropotkin.--Paul Bourget.--Thomas Hardy.--Ehrlich of "606".--Louis Sullivan: a great architect.--Eugene Fromentin: the painter writer.--Sir Herbert Tree.--Flaubert and his letters.--Hatred in art: Leon Bloy.--Three generations of Morgans.--The brothers de Goncourt and realism.--Lord Hartington.--Ambassador Bernstorff.--A talk with A.E. Housman.--Paul Deschanel.--Frederic Harrison: the last of the Victorians.--Annie Besant: rebel and reformer.--John Churton Collins.--Hyndman, the communist.--Horace Traubel.--Joseph Caillaux.

Alexander Balus. [music] : an oratorio /

Original work composed in 1747, first produced in 1748.

Défense des trois chapitres (à Justinien) /

Includes bibliographical references (p. [135]-138) and indexes.

Sea-sickness: cause, prevention, and cure. Voyaging for health, with an appendix on ship-surgeons. A concise practical treatise

Mode of access: Internet.

Sediment suspension and turbulence in an oscillating flume /

"April 1977."

A challenge to historians,

Mode of access: Internet.