Techniques were developed for extracting histones from isolated
chromatin of encysted embryos of Artemia salina. Histone extracts
from embryos collected at eight time intervals after rehydration and
initiation of development were analyzed by electrophoresis for qualitative
and quantitative changes in composition. Histone to DNA ratios
were determined for the same...
Glutamine synthetase in the embryonic chick neural retina
shows a 50 fold increase in activity between the 16th and 17th day of
embryonic development. This increase in enzyme activity results
from de novo enzyme synthesis thus making it a useful marker of
differential gene expression. A precocious rise in activity...
Developmental changes in the enzymes acetylcholinesterase
(EC 3.1.1.7) and pseudocholinesterase (EC 3.1.1.8) were
examined in ovo and in vitro in the neural retina of the
developing chick. In addition, investigations of cellular
interactions and hormones as possible control mechanisms of
enzyme synthesis were made.
The specific activity of acetylcholinesterase, a...
Glycosaminoglycans, highly anionic long chains of repeating disaccharides,
are present in the extracellular matrix of almost all
vertebrate tissues. In addition to their structural role in adult
tissues, these molecules have been implicated as mediators of
important developmental processes such as cell migration, cell-cell
recognition and adhesion, and cytodifferentiation. The...
Sialic acids are involved in many cellular interactions. They can serve as an adhesion ligand or act as an inhibitor to cellular adhesion by charge repulsion or by masking potential ligands. Although sialic acids are implicated in the process of blastocyst implantation, their expression and regulation in uterine epithelium of...
Plant sexual reproduction requires a broad array of molecular mechanisms to proceed successfully. Some of these mechanisms are well-studied, but our knowledge of them as a whole is fundamentally incomplete. Pollen tube growth is a key part of this process, facilitating the delivery of the sperm cells to the female...
Tension relationships were determined in steel cable passed through a stump notch and anchored to another object. Tensions were measured in the cable coming into and leaving the notch with one full wrap on the stump. Data was collected from two sites with two test stumps (15.7 to 37.5 inches...
