Myxine formosana, a new species of hagfish (Myxiniformes: Myxinidae) from the southwestern waters of Taiwan

Myxine formosana, a new hagfish species, is described on the basis of the specimens from the Pacific Ocean southwest of Taiwan at depths 588–1500 m. It is five-gilled and white-headed with a three-cusp multicusp on the anterior set of cusps and a two-cusp multicusp on the posterior set. Myxine formosana, M. circifrons, M. mccoskeri, and M. robinsi are superficially rather similar, but M. formosana has low to vestigal caudal finfolds. It is the first record of the genus Myxine from Taiwan. Received: October 25, 2000 / Revised: March 17, 2001 / Accepted: April 21, 2001     

A tethered catalysis, two-hybrid system to identify protein-protein interactions requiring post-translational modifications

We have modified the yeast two-hybrid system to enable the detection of protein-protein interactions that require a specific post-translational modification, using the acetylation of histones and the phosphorylation of the carboxyl terminal domain (CTD) of RNA polymerase II as test modifications. In this tethered catalysis assay, constitutive modification of the protein to be screened for interactions is achieved by fusing it to its cognate modifying enzyme, with the physical linkage resulting in efficient catalysis. This catalysis maintains substrate modification even in the presence of antagonizing enzyme activities. A catalytically inactive mutant of the enzyme is fused to the substrate as a control such that the modification does not occur; this construct enables the rapid identification of modification-independent interactions. We identified proteins with links to chromatin functions that interact with acetylated histones, and proteins that participate in RNA polymerase II functions and in CTD phosphorylation regulation that interact preferentially with the phosphorylated CTD.     

Increased A beta peptides and reduced cholesterol and myelin proteins characterize white matter degeneration in Alzheimer's disease

Relative to the gray matter, there is a paucity of information regarding white matter biochemical alterations and their contribution to Alzheimer's disease (AD). Biochemical analyses of AD white matter combining size-exclusion, normal phase, and gas chromatography, immunoassays, and Western blotting revealed increased quantities of Abeta40 and Abeta42 in AD white matter accompanied by significant decreases in the amounts of myelin basic protein, myelin proteolipid protein, and 2',3'-cyclic nucleotide 3'-phosphodiesterase. In addition, the AD white matter cholesterol levels were significantly decreased while total fatty acid content was increased. In some instances, these white matter biochemical alterations were correlated with patient apolipoprotein E genotype, Braak stage, and gender. Our observations suggest that extensive white matter axonal demyelination underlies Alzheimer's pathology, resulting in loss of capacitance and serious disturbances in nerve conduction, severely damaging brain function. These white matter alterations undoubtedly contribute to AD pathogenesis and may represent the combined effects of neuronal degeneration, microgliosis, oligodendrocyte injury, microcirculatory disease, and interstitial fluid stasis. To accurately assess the success of future therapeutic interventions, it is necessary to have a complete appreciation of the full scope and extent of AD pathology.     

Characterization of a Saccharomyces cerevisiae mutant with oversecretion phenotype

An oversecreting mutant of Saccharomyces cerevisiae was obtained from about 400 meiotic segregants derived from thediploid cells made by crossing the HBsAg-induced mutant NI-C with the wild-type strain Sey6211. When transformed with a plasmid containing mouse alpha-amylase cDNA, the mutant (NI-C-D4) exhibited an increased capacity (up to 13-fold) for the secretion of mouse alpha-amylase, higher than the parental strains and other standard wild-type strains. It was also shown that alpha-amylase secreted by the oversecreting mutant had a higher activity and contained more of the non-glycosylated form than the glycosylated form. This isolated oversecreting, low-glycosylation mutant may prove to be a potential S. cerevisiae host for the production of foreign proteins. Further genetic analysis suggested that the mutation responsible for the mutant's oversecretion was partially dominant and that both the oversecretion and low-glycosylation phenotypes were governed by a single chromosome mutation. These pleiotrophic phenotypes may be attributed to a defect in the synthesis of an ER-resident chaperone.     

Selection of valid and reliable EEG features for predicting auditory and visual alertness levels

A selection procedure with three rules, high efficiency, low individual variability, and low redundancy, was developed to screen electroencephalogram (EEG) features for predicting behavioral alertness levels. A total of 24 EEG features were derived from temporal, frequency spectral, and statistical analyses. Behavioral alertness levels were quantified by correct rates of performance on an auditory and a visual vigilance task, separately. In the auditory task study, a subset of three EEG features, the relative spectral amplitudes in the alpha (alpha%, 8-13 Hz) and theta (theta%, 4-8 Hz) bands, and the mean frequency of the EEG spectrum (MF), was found to be the best combination for predicting the auditory alertness level. In the visual task study, the mean frequency of the beta band (Fbeta, 13-32 Hz) was the only EEG feature selected. The application of an averaging subwindow procedure within a moving time window to EEG analysis increased the predictive power of EEG features and decreased the disturbing effect of movement artifacts on the EEG data.     

Beyond the catalytic core of ALDH: a web of important residues begins to emerge

Site-directed mutagenesis was performed in class 3 aldehyde dehydrogenase (ALDH) on both strictly conserved, non-glycine residues, Glu-333 and Phe-335. Both lie in Motif 8 and are indicated to be of central catalytic importance from their positions in the tertiary structure. In addition, a highly conserved residue at the end of Motif 8, Pro-337, and Asp-247, which interacts with the main chain of Motif 8, were also mutated. All substitutions were conservative. Kinetic values clearly show that Glu-333 and Phe-335 are crucial to efficient catalysis, along with Asp-247. Pro-337 appears to have a different role, most likely relating to folding.