We have analysed genetic systems of flower development and of root gravitropism of higher plant using Arabidopsis thaliana, which has several features suited for molecular genetic studies. Through isolation and analyses of many mutants which carry genetic defect(s) in the processes of floral development or of root gravitropic response, sets of genes involved in those processes are identified.
In a lower invertebrate hydra, growth factors appear to be released after food intake. We found that the growth factors depressed the feeding response. We also found a phasic increase of acidic FGF activity after food intake in cerebrospinal fluid from canulated rats. These observations suggest a close relationship between food intake and growth factors from hydra to mammals.
Protein translocation across the membrane is a key reaction in the biogenesis of noncytoplasmic proteins. Topogenic signals carried on various portions of the polypeptide, as well as proteinaceous factors play essential roles in the asymmetric protein-membrane interaction. Factors mediating co-translational translocation as well as factors modulating the folding pathway of polypeptides for post-translational translocation have been identified. The SecY protein of E. coli is an integral membrane component that facilitates the translocation step, possibly by forming a channel for polypeptide passage.
During head assembly of the double-stranded DNA bacteriophages, DNA is packaged into a preformed protein shell, called the prohead, with the aid of noncapsid, packaging proteins. We have constructed a defined in vitro system for packaging of phage T3 DNA. In the defined system, DNA is translocated synchronously into the prohead. From the analysis of the defined in vitro system, the molecular mechanism of DNA translocation is discussed.
Many sequence specific DNA-binding proteins induce structural distortions upon binding to DNA such as DNA bending and DNA looping. The cAMP receptor protein of Escherichia coli assumes the role of the prototypical DNA-bending protein. The functional role of protein-induced DNA bending remain to be solved. DNA looping has been demonstrated between repressor molecules bound cooperatively at separated sites in some regulatory systems. Thus regulatory proteins can influence the activity of another protein at a distance.
Mother-infant pair of Japanese greater horseshoe bat shows discriminative nursing. The key of their recognition was traced in vocal interaction in retrieval behavior. The significane of main character, synchronization of their pulse was considered on reference to our telecommunication.
Self-organization, which proceeds continuously with macroscopic order due to internal force alone in many biological systems, is embodied by the coupling of a primary and some partial systems to control the primary system slowly in general. By developing a simple dynamic and a chemical network model for self-organization, the behavior or unstability of such a coupled system is discussed with transition parameter k, which represents the change in the internal force and the sign change gives the potential bifurcation. This dynamical theory is further applied to membrane excitation based on the catastrophe theory.
A series of studies on the conformation, properties, and antitumor activity of schizophyllan, an extracellular β-1, 3-D-glucan, in aqueous solution are reviewed. The polysaccharide exists as a triple-stranded helix in aqueous solution if the molecular weight is higher than 105. This helical structure is responsible for the potent antitumor activity of the glucan.
Our recent FT-IR-ATR (Fourier Transform-Infrared-Attenuated Total Reflection) spectroscopic studies on eye tissues and internal organs have demonstrated that this technique is very useful and unique in investigating biological molecules near the surface of biological tissues in a nondestructive manner.