Expression of Frizzled genes in the developing chick eye

Frizzleds are transmembrane receptors that can transduce signals dependent upon binding of Wnts, a large family of secreted glycoproteins homologous to the Drosophila wingless (wg) gene product and critical for a wide variety of normal and pathological developmental processes. In the nervous system, Wnts and Frizzleds play an important role in anterior-posterior patterning, cell fate decisions, proliferation, and synaptogenesis. However, little is known about the role of Frizzled signaling in the developing eye. We isolated cDNAs for ten chick Frizzleds and analyzed the spatial and temporal expression patterns during eye development in the chick embryo. Frizzled-1 to -9 are specifically expressed in the eye at various stages of development and show a complex and partially overlapping pattern of expression.     

Bayesian restoration of ion channel records using hidden Markov models

Hidden Markov models have been used to restore recorded signals of single ion channels buried in background noise. Parameter estimation and signal restoration are usually carried out through likelihood maximization by using variants of the Baum-Welch forward-backward procedures. This paper presents an alternative approach for dealing with this inferential task. The inferences are made by using a combination of the framework provided by Bayesian statistics and numerical methods based on Markov chain Monte Carlo stochastic simulation. The reliability of this approach is tested by using synthetic signals of known characteristics. The expectations of the model parameters estimated here are close to those calculated using the Baum-Welch algorithm, but the present methods also yield estimates of their errors. Comparisons of the results of the Bayesian Markov Chain Monte Carlo approach with those obtained by filtering and thresholding demonstrate clearly the superiority of the new methods.     

Different antagonist binding properties of human and rat histamine H3 receptors

Different histamine H3-receptor antagonists have been tested in displacement studies at human and rat H3 receptors in stably transfected cells. Based on an actual rhodopsin structure, models for receptor antagonist interaction were developed for receptors of both species. Similarities and discrepancies in binding profiles can be explained, but not quantified by hydrophilic interactions with Asp114 and an important lipophilic binding pocket modified by two nearby amino acids.     

Presence of the bacterial hemoglobin gene improves α-amylase production of a recombinantEscherichia coli strain

A recombinant plasmid (pMK57) was constructed by cloning theBacillus stearothermophilus α-amylase gene into pUC8; plasmid pMK79 was then derived from pMK57 by inserting the bacterial (Vitreoscilla) hemoglobin gene into the latter plasmid. Both pMK57 and pMK79 were transformed intoEscherichia coli strain JM103 to make strains MK57 and MK79, respectively. Both MK57 and MK79 produced α-amylase and MK79 produced hemoglobin. MK79 outgrew MK57 in shake flasks in LB medium, the advantage of the former appearing in late log phase. MK79 produced more α-amylase than MK57, on both per cell and per volume bases, in both mid and late log phases; the maximum advantage of MK79 (on a per volume basis) occurred in late log phase, at which time it produced 3.3 times as much α-amylase as MK57. The numbers of copies per cell of both pMK57 and pMK79 were significantly lower than that of pUC8.     

Cloning and expression of the Vitreoscilla hemoglobin gene in pseudomonads: effects on cell growth

The gene (vgb) encoding the hemoglobin (VtHb) of Vitreoscilla sp. was cloned into a broad-host-range vector and stably transformed into Pseudomonas putida, Pseudomonas aeruginosa, and Xanthomonas maltophilia. vgb was stably maintained and expressed in functional form in all three species. When growth of the P. aeruginosa and X. maltophilia transformants in Luria-Bertani medium was compared with that of each corresponding untransformed strain, the VtHb-producing strains reached slightly higher maximum viable cell numbers, had significantly increased viability after extebded times in culture, and, like E. coli that produces VtHb, had significantly lower respiration rates. The VtHb-producing strain of P. putida also reached a slightly higher maximum viable cell number than its corresponding untransformed strain, but was significantly less viable after extended times in culture and, unlike the case in E. coli, had a generally higher respiration rate than the untransformed strain. When growth was monitored by absorbance, the results were similar to those obtained with viable cell counts.