The Jolly Student : Characteristic March-Two-Step

https://digitalcommons.library.umaine.edu/mmb-ps/1326/thumbnail.jp

Association of the Dictyostelium 30 kDa actin bundling protein with contact regions

\u27Contact regions\u27 are plasma membrane domains derived from areas of intercellular contact between aggregating Dictyostelium amebae (H.M. Ingalls et al. (1986). Proc. Nat. Acad. Sci. USA 83, 4779). Purified contact regions contain a prominent actin-binding protein with an M(r) of 34,000. Immunoblotting with monoclonal antibodies identifies this polypeptide as a 34,000 M(r) actin-bundling protein (known as 30 kDa protein), previously shown to be enriched in filopodia (M. Fechheimer (1987). J. Cell Biol. 104, 1539). About four times more 30 kDa protein by mass is associated with contact regions than is found in total plasma membranes isolated from aggregating cells. In agreement with these observations, immunostaining of the 30 kDa protein in aggregating cells reveals a prominent localization along the plasma membrane at sites of intercellular contact. By contrast, alpha-actinin does not appear to be significantly enriched at sites of cell to cell contact. Binding experiments using purified plasma membranes, actin and 30 kDa protein indicate that the 30 kDa protein is associated with the plasma membrane primarily through interactions with actin filaments. Calcium ions are known to decrease the interaction of actin with 30 kDa protein in solution. Surprisingly, membrane-associated complexes of actin and the 30 kDa protein are much less sensitive to dissociation by micromolar levels of free calcium ions than are complexes in solutions lacking membranes

Avian W and mammalian Y chromosomes convergently retained dosage-sensitive regulators

After birds diverged from mammals, different ancestral autosomes evolved into sex chromosomes in each lineage. In birds, females are ZW and males are ZZ, but in mammals females are XX and males are XY. We sequenced the chicken W chromosome, compared its gene content with our reconstruction of the ancestral autosomes, and followed the evolutionary trajectory of ancestral W-linked genes across birds. Avian W chromosomes evolved in parallel with mammalian Y chromosomes, preserving ancestral genes through selection to maintain the dosage of broadly expressed regulators of key cellular processes. We propose that, like the human Y chromosome, the chicken W chromosome is essential for embryonic viability of the heterogametic sex. Unlike other sequenced sex chromosomes, the chicken W chromosome did not acquire and amplify genes specifically expressed in reproductive tissues. We speculate that the pressures that drive the acquisition of reproduction-related genes on sex chromosomes may be specific to the male germ line

Ding dong ding dong ding dong, comes the sweet refrain, [first line of chorus]

Performers: Reese V. ProsserPiano and Voice (with lyrics

Dairy science, 1970

Environmental pollution and the Ohio farmer / W. M. Edwards -- The effect of rubber vs. plastic inflations on milking rate and udder health / R. M. Porter, H. E. Kaeser, R. D. Buller and F. R. Allaire -- Ground soybeans in dairy rations / J. W. Hibbs and H. R. Conrad -- High moisture corn for lactating dairy cows / D. L. Palmquist -- Cows milk well when grazing high protein forage / H. R. Conrad, R. W. Wallenius and R. W. Van Keuren -- Effects of feeding high levels of grain to growing Holstein heifers / D. E. Pritchard -- Selection of a feeding program for dairy cows / H. M. Keener and H. R. Conrad -- Antigen-antibody interactions and reproductive performance / H. C. Hines -- Chromosomal abnormalities as a cause of infertility and embryo death / N. S. Fechheimer -- The cause of abnormalities with which calves are born / L. O. Gilmore and N. S. Fechheime