Conservative Site Research Articles

Mutations in MTO2 Related to tRNA Modification Impair Mitochondrial Gene Expression and Protein Synthesis in the Presence of a Paromomycin Resistance Mutation in Mitochondrial 15 S rRNA

Nuclear gene(s) have been shown to modulate the phenotypic expression of mitochondrial DNA mutations. We report here the identification and characterization of the yeast nuclear gene MTO2 encoding an evolutionarily conserved protein involved in mitochondrial tRNA modification. Interestingly, mto2 null mutants expressed a respiratory-deficient phenotype when coexisting with the C1409G mutation of mitochondrial 15 S rRNA at the very conservative site for human deafness-associated 12 S rRNA A1491G and C1409T mutations. Furthermore, the overall rate of mitochondrial translation was markedly reduced in a yeast mto2 strain in the wild type mitochondrial background, whereas mitochondrial protein synthesis was almost abolished in a yeast mto2 strain carrying the C1409G allele. The other interesting feature of mto2 mutants is the defective expression of mitochondrial genes, especially CYTB and COX1, but only when coexisting with the C1409G allele. These data strongly indicate that a product of MTO2 functionally interacts with the decoding region of 15 S rRNA, particularly at the site of the C1409G or A1491G mutation. In addition, we showed that yeast and human Mto2p localize in mitochondria. The isolated human MTO2 cDNA can partially restore the respiratory-deficient phenotype of yeast mto2 cells carrying the C1409G mutation. These functional conservations imply that human MTO2 may act as a modifier gene, modulating the phenotypic expression of the deafness-associated A1491G or C1409T mutation in mitochondrial 12 S rRNA.

Estrogen modulates the expression of L-arginine:glycine amidinotransferase in chick liver.

Identification of estrogen-responsive genes is important to understand the molecular mechanisms of estrogen action. Suppression subtractive hybridization was employed to screen estrogen-responsive genes in chick liver. A single injection of estrogen into 6-week-old chick induced up-regulation of several known genes encoded for yolk proteins, such as Vitellogenin I and II and very low density lipoprotein II (apo-VLDL II). One novel sequence displayed a dramatic change (3-fold increase) in response to estrogen treatment. This cDNA fragment was extended and the resultant sequence was analyzed. Translated amino acid sequence was 90, 88, 83 and 87% identical to the L-arginine:glycine amidinotransferase of pig, rat, frog and human, respectively. The sequence has a conservative catalytic site of L-arginine: glycine amidinotransferase. The expression pattern of this gene in organs is consistent with previous reports of L-arginine:glycine amidinotransferase in chick. Thus, this clone represented the chicken L-arginine:glycine amidinotransferase. It appeared that estrogen-induced alteration of arginine:glycine amidinotransferase was not dependent on protein synthesis, because concurrent administration of cycloheximide did not affect the estrogen-mediated expression pattern. This is the first study demonstrating that L-arginine:glycine amidinotransferase is a target of the estrogen receptor.

On-Site Wastewater Treatment Using Wisconsin Mounds on Difficult Sites

ABSTRACT THE Wisconsin mound system, using relatively conservative soil site criteria, has been accepted by many states as an alternative for sites not suitable for the in-ground soil absorption system. An experimental program was initiated in 1978 to evaluate soil site limitations for the Wisconsin mound by installing full size units on home sites with failing systems. Based on evaluation of over 40 systems, 11 of which are described in detail, mounds can be placed (a) on sites with high water tables approaching 25 cm of the surface, (b) on slowly permeable soils with permeabilities in the moderately low to low categories, (c) on slopes up to 20-25%, (d) over existing in-ground systems, and (e) on filled sites. The performance of the sites has been very good. During extremely wet weather on the more slowly permeable soils, there may be some leakage at the toe of the mound. The quality of the leakage is very good with very low fecal coliform counts. Mounds can be placed on much more restrictive sites if the system is designed using linear loading rates that fit the site and if correct construction and siting procedures are followed.

Introduction to the special session on construction noise

As an introduction to the session on construction noise at University Park, PA, the state of the art in construction equipment and site noise prediction, measurement and control will be reviewed. Typical construction equipment and site noise levels will be indicated. Standard procedures to measure equipment noise levels, particuarly SAE J88 and J88a, will be reviewed. Construction-site noise levels predicted by adding worst-case equipment noise levels, result in conservative site levels, since not all equipment operate simultaneously. Alternative techniques to predict either maximum likely, equivalent (Leq) or statistical (Ln) noise levels instead of maximum noise levels will be described. The existing state of the art in construction noise control will be illustrated in terms of noise control for portable air compressors and pile drivers.