Yeast Kre2 Defines a New Gene Family Encoding Probable Secretory Proteins, and Is Required for the Correct N-Glycosylation of Proteins

We have cloned, sequenced and disrupted the KRE2 gene of Saccharomyces cerevisiae, identified by killer-resistant mutants with a defective cell wall receptor for the toxin. The KRE2 gene is close to PHO8 on chromosome 4, and encodes a predicted 49-kD protein, Kre2p, that probably enters the secretory pathway. Haploid cells carrying a disruption of the KRE2 locus grow more slowly than wild-type cells at 30 degrees, and fail to grow at 37 degrees. At 30 degrees, kre2 mutants showed altered N-linked glycosylation of proteins, as the average size of N-linked outer chains was reduced. We identified two other genes, YUR1 on chromosome 10, and KTR1 on chromosome 15, whose predicted products share 36% identity with Kre2p over more than 300 amino acid residues. Yur1p has an N-terminal signal sequence like Kre2p, while Ktr1p has a predicted topology consistent with a type 2 membrane protein. In all cases the conserved regions of these proteins appear to be on the lumenal side of secretory compartments, suggesting related function. KRE2, KTR1 and YUR1 define a new yeast gene family.     

Chemoprevention clinical trials.

As part of a program to develop drugs which will delay or prevent cancer in humans, the Chemoprevention Branch, National Cancer Institute, National Institutes of Health, is sponsoring 12 Phase I and 22 Phase II and III clinical trials. Three agent classes are significantly advanced in the trials. These are the retinoids, including 13-cis-retinoic acid, retinol, and 4-hydroxyphenylretinamide (nine studies), beta-carotene (seven studies), and calcium compounds (three studies). In addition, six promising new compounds are in Phase I or Phase II trials. These are: piroxicam, ibuprofen, oltipraz (a dithiolthione), difluoromethylornithine, glycyrrhetinic acid, and N-acetylcysteine. Key concepts related to the development of cancer chemopreventive agents are (1) the need for long-term administration, (2) the need for oral route of administration, (3) the matching of toxic side effects to degree of cancer risk.     

Plate-Induced tumors of BALB/3T3 cells exhibiting foci of differentiation into pericytes,chondrocytes, and fibroblasts

The BALB/3T3 clone A31 mouse embryo cell line has been used by many investigators as a model “normal” “fibroblast” line for a variety of in vitro studies. It has been shown, however, that these cells are not “normal” because they will produce tumors within 2–4 months if 3 × 10⁴ cells are implanted subcutaneously in BALB/c mice attached to 0.2 × 5 × 10-mm plastic plates. Previous studies also suggested that these cells were not fibroblasts because they gave rise to tumors with the characteristics of vascular endothelium not fibroblasts. We now report that BALB/3T3 (clone A31), BALB/3T3-T, a proadipocyte subclone of clone A31 cells, and six recent subclones of BALB/3T3-T cells show additional differentiation patterns when tumors derived by implantation of these cells attached to plastic plates are examined. Differentiation into pericytes, chondrocytes, and fibroblasts was observed. We conclude that the BALB/3T3 clone A31 cell line and related lines are multipotent mesenchymal cells which are capable of differentiation into a variety of cell types.     

Selective growth of malignant cells by in vitro incubation on Teflon

The selective growth of malignant cells on non-adhesive Teflon substrates is reported. Neoplastically transformed cell lines of human and murine origin proliferated on Teflon whereas similarly seeded normal non-tumorigenic cells were unable to undergo cell division and subsequent growth. This substrate should be especially useful in establishing primary cultures from human tumor material.     

Influence of nutrition on reproduction in the ewe with special emphasis on progesterone concentration.

Influence of nutrition on lambing rate and progesterone levels was studied in Rambouillet ewes. In the first experiment, two groups of 10 ewes each were individually fed on a diet containing either high (3.04 kg/day) or low (1.89 kg/day) levels of total digestible nutrients. Ewes on the High Plane of nutrition had lower pregnancy rates and fewer lambs than the ewes on the Low Plane. Plasma progesterone concentration was not significantly different between treatment groups when compared before and after mating.In the second experiment two groups of 25 ewes each were grazed on pasture and supplemented with a pelleted concentrate. One group was fed to gain weight, while the other group was fed to maintain their body weight. There was no significant difference in lambing rate between these two groups.     

Allometric Models for Predicting Aboveground Biomass in Two Widespread Woody Plants in Hawaii

Allometric models are important for quantifying biomass and carbon storage in terrestrial ecosystems. Generalized allometry exists for tropical trees, but species‐ and site‐specific models are more accurate. We developed species‐specific models to predict aboveground biomass in two of the most ubiquitous natives in Hawaiian forests and shrublands, Metrosideros polymorpha and Dodonaea viscosa. The utility of the M. polymorpha allometry for predicting biomass across a range of sites was explored by comparing size structure (diameter at breast height vs. tree height) of the trees used to develop the models against trees from four M. polymorpha‐dominated forests along a precipitation gradient (1630–2380 mm). We also compared individual tree biomass estimated with the M. polymorpha model against existing generalized equations, and the D. viscosa model with an existing species‐specific model. Our models were highly significant and displayed minimal bias. Metrosideros polymorpha size structures from the three highest precipitation sites fell well within the 95% confidence intervals for the harvested trees, indicating that the models are applicable at these sites. However, size structure in the area with the lowest precipitation differed from those in the higher rainfall sites, emphasizing that care should be taken in applying the models too widely. Existing generalized allometry differed from the M. polymorpha model by up to 88 percent, particularly at the extremes of the data range examined, underestimating biomass in small trees and overestimating in large trees. The existing D. viscosa model underestimated biomass across all sizes by a mean of 43 percent compared to our model. The species‐specific models presented here should enable more accurate estimates of biomass and carbon sequestration in Hawaiian forests and shrublands.     

Use of freeze-cracking in ontogenetic research in <Emphasis Type="Italic">Macrostomum lignano</Emphasis> (Macrostomida,Rhabditophora)

A method for studying whole mount flatworm embryos based on freeze-cracking of the eggs is described. This method allows successful immunohistological and immunocytological studies of whole mount embryos. It does not require the use of sharpened needles or a microinjection system to puncture the eggshell. Moreover, this method is more practical and less time-consuming than classical puncturing and much cheaper than the use of a microinjection system. The advantages of this method are illustrated by results of several immunolocalisation experiments in the macrostomid flatworm Macrostomum lignano. The optimal procedure and crucial steps for this method are discussed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.