Naturliebhaberei und Jugend : Fortsetzung

Von Johs. Peter

Naturliebhaberei und Jugend

Von Johs. Peter

Mein erster Zuchterfolg bei Molge pyrrhogastra, Rotbauchmolch aus Japan

Von Johs. Peter

Effect of Water Stress on Cell Division and Cdc2-Like Cell Cycle Kinase Activity in Wheat Leaves1

In wheat (Triticum aestivum) seedlings subjected to a mild water stress (water potential of −0.3 MPa), the leaf-elongation rate was reduced by one-half and the mitotic activity of mesophyll cells was reduced to 42% of well-watered controls within 1 d. There was also a reduction in the length of the zone of mesophyll cell division to within 4 mm from the base compared with 8 mm in control leaves. However, the period of division continued longer in the stressed than in the control leaves, and the final cell number in the stressed leaves reached 85% of controls. Cyclin-dependent protein kinase enzymes that are required in vivo for DNA replication and mitosis were recovered from the meristematic zone of leaves by affinity for p13suc1. Water stress caused a reduction in H1 histone kinase activity to one-half of the control level, although amounts of the enzyme were unaffected. Reduced activity was correlated with an increased proportion of the 34-kD Cdc2-like kinase (an enzyme sharing with the Cdc2 protein of other eukaryotes the same size, antigenic sites, affinity for p13suc1, and H1 histone kinase catalytic activity) deactivated by tyrosine phosphorylation. Deactivation to 50% occurred within 3 h of stress imposition in cells at the base of the meristematic zone and was therefore too fast to be explained by a reduction in the rate at which cells reached mitosis because of slowing of growth; rather, stress must have acted more immediately on the enzyme. The operation of controls slowing the exit from the G1 and G2 phases is discussed. We suggest that a water-stress signal acts on Cdc2 kinase by increasing phosphorylation of tyrosine, causing a shift to the inhibited form and slowing cell production.

A plan of Cambridge Green, 1780 September 14

Small pen-and-ink and watercolor drawing of Cambridge Green created by Harvard senior John Davis, presumably as part of his undergraduate mathematical coursework. The map surveys Cambridge Commons and includes a few rough outlines of College buildings and the Episcopal church, and notes the burying ground, and the roads to Charlestown, Menotomy, the pond, Watertown, and the bridge. The original handwritten text is faded and was annotated with additional text by Davis including the note "[taken in my Senior year at H. College Septr 1780] Surveyed in concert with classmates, Atkins, Hall 1st, Howard, Payne, &c.- J. Davis." There is a note that "Atkins afterwards took the name of Tying." Davis refers to Dudley Atkins Tyng, Joseph Hall, Bezaleel Howard, and Elijah Paine, all members of the Harvard Class of 1781.

Account book : manuscript, 1793-1869

Account of cash paid out to various people.

Carbon printing,

Imprint covered by label: London, Iliffe & Sons, limited.

The birds of Dorsetshire; a contribution to the natural history of the county,

Mode of access: Internet.

Bell-founders in Lancashire and Cheshire and the adjacent counties, in the seventeenth and eighteenth centuries; a paper, read before the Historic Society of Lancashire and Cheshire, 6th March, 1890.

Mode of access: Internet.

In my Indian garden / with a preface by Edwin Arnold.

An enlarged edition of the author's Nugae Indicae.

Joannes Matthaeus and his tract "De rerum inventoribus".

Pt. I, read before the Society Dec. 4, 1901; Pt. II, read Dec. 18, 1916.

Colouring matters for dyeing textiles; with numerous engravings and diagrams,

"The matter has been revised and brought up to date by Mr. A. R. Foster."--Pref.

The Daśakumâracarita of Daṇḍin /

Part 2 edited by Peter Peterson.

The Cosmopolitan.

Editor: John B. Walker, 1889-1905.

Sociology, or the science of institutions,

"Extract from the twentieth annual report of the Bureau of American Ethnology."