Effects of light, temperature, gibberellin (GA3) and their interaction on coleoptile and leaf elongation of tall, semi-dwarf and dwarf wheat

Near-isogenic wheat lines differing in height-reducing (Rht) alleles, in each of two cultivars, were used to investigate the effects of light intensity and of their interaction with temperature and GA₃ application, on the elongation of the coleoptile and the first seedling leaf. Darkness caused a conspicuous increase in the lengths of the coleoptile and of the sheath and lamina of the first leaf, in GA₃ treated and untreated seedlings of all genotypes grown at 11 and 25°C. The genotype effects and the effects of light intensity and GA₃ application on leaf length were ascribed entirely to their effects on the rate of leaf elongation since the duration of leaf elongation was not affected by these factors. Temperature elevation from 11 to 25°C caused a 55% shortening of the duration of leaf elongation and a concomitant increase in elongation rate, which diminished with increased genotypic dwarfness. Accordingly, temperature elevation resulted in a significant reduction in leaf-length of the light-grown dwarf genotypes and the dark-grown dwarf and semi-dwarf genotypes. It is suggested that this temperature × light × genotype interaction effect is due to environmental dependent upper limits of elongation rate set by the Rht alleles.Abbreviations PAR Photosynthetic Active Radiation     

Age-related differences in TGF-α and proto-oncogenes expression in rat liver after a low dose of carbon tetrachloride

The resiliency of rats during early postnatal development to CCl₄ or to an interactive hepatotoxicity of chlordecone (CD) + CCl₄ has been shown to be due to an efficient stimulation of tissue repair. The objective of the current study was to investigate if this is due to efficient expression of transforming growth factor-α (TGF-α) and proto-oncogenes. Postnatally developing (20 day old) and adult (60 day old) male Sprague–Dawley rats were challenged with a single low dose of CCl₄ (100 μL/kg, ip) or corn oil. Liver samples were collected during a time course (0–96 h) after the administration of CCl₄ and used to examine TGF-α and early (c-fos) and late (H-ras and K-ras) proto-oncogenes mRNA expressions. Significant increases in TGF-α, H-ras, and K-ras gene expressions were evident as early as 12 hours after CCl₄ and peaked between 24 and 48 hours in an age-dependent manner as detected by slot-blot analysis. Results of the study revealed three- and twofold increases in TGF-α gene expression in 20 and 60 day old rats, respectively, after CCl₄. There were 3.5- and 2.5-fold increases in H-ras and 4.4- and 3.4-fold increases in K-ras in 20 and 60 day old rats, respectively. In contrast, a 10-fold increase in c-fos mRNA expression was evident in 20 day old rats 1 hour after CCl₄ treatment, returning to the baseline value by 3 hours, whereas in 60 day old rats, this increase was less than twofold. The overall findings of this study indicate that TGF-α and the early and late proto-oncogene mRNA expressions were enhanced in an age- and time-dependent manner in response to a low dose of CCl₄. These results further strengthen the view that the remarkable resiliency of rats to hepatotoxicants during early postnatal development is due to substantial increases in stimulation of hepatocellular regeneration and tissue repair mechanisms, leading to regression of liver injury and recovery. © 1996 John Wiley & Sons, Inc.     

Fewer protective cytotoxic T-cell epitopes than T-helper-cell epitopes on vesicular stomatitis virus.

Cytotoxic T-lymphocyte (CTL) and T-helper-cell responses in various mouse strains were monitored. Protective CTL responsiveness against three proteins of vesicular stomatitis virus was H-2 linked and inducible only in half of the 15 combinations tested (each of five H-2 haplotypes combined with each of three viral proteins), whereas biologically relevant T-helper-cell responses were inducible in all. This suggests that vesicular stomatitis virus exhibits more T-helper-cell than CTL epitopes.     

BRCA1 maps proximal to D17S579 on chromosome 17q21 by genetic analysis

Previous studies have demonstrated linkage between early-onset breast cancer and ovarian cancer and genetic markers on chromosome 17q21. These markers define the location of a gene (BRCA1) which appears to be inherited as an autosomal dominant susceptibility allele. We analyzed five families with multiple affected individuals for evidence of linkage to the BRCA1 region. Two of the five families appear to be linked to BRCA1. One apparently linked family contains critical recombinants, suggesting that the gene is proximal to the marker D17S579 (Mfd188). These findings are consistent with the maximum-likelihood position estimated by the Breast Cancer Linkage Consortium and with recombination events detected in other linked families. Linkage analysis was greatly aided by PCR-based analysis of paraffin-embedded normal breast tissue from deceased family members, demonstrating the feasibility and importance of this approach. One of the two families with evidence of linkage between breast cancer and genetic markers flanking BRCA1 represents the first such family of African-American descent to be reported in detail.     

Daily Rhythms of Body Temperature in Acornys russatus: The Response to Chemical Signals Released by Acomys cahirinus

Two species of spiny mice of the genus Acomys—the golden spiny A. russaturs and the common spiny A. cuhirinus—are syrnpatnc in the and and hot parts of the Rift Valley in Israel. The coexistence of these two species is due to exclusion of A. russatus mice by A. cuhirinus mice from nocturnal activity. The aim of this research was to study if odor signals released by A. cahirinus mice can play a role in the exclusion of A. russatus mice. A. russatus mice with an implanted transmitter recording body temperature (T_b) were kept alone in a metabolic chamber under constant conditions of ambient temperature (27°C) and photoperiod (12 h light: 12 h dark). After 5 days of recording, chemical signals from an A. cuhirinus mouse were added through the air tube going into the metabolic chamber of the A. russatus mice. This treatment caused a shift of ∼ 2 h inT_b daily rhythm of the naive tested A. russutus mice, whereas no shift was observed in A. russatus mice that had been kept in the same room with the A. cahirinus mouse before measurements. These results strongly support the idea that chemical signals released by A. cahirinus mice can entrain the T_b rhythms of A. russatus mice. Therefore, it may be assumed that the exclusion of A. russatus mice from nocturnal activity by A. cuhirinus mice could be achieved through the odor released by the latter.     

Canadian outpatients and advance directives: poor knowledge and little experience but positive attitudes.

OBJECTIVE: To examine the knowledge of, previous experience with, attitudes toward and perceived barriers to completing advance directives among outpatients at two general medicine clinics. DESIGN: Cross-sectional questionnaire administered in face-to-face structured interviews. SETTING: General internal-medicine outpatient clinics at a university teaching hospital. PATIENTS: One hundred and five adult outpatients who could communicate in spoken English and who consented to be interviewed. RESULTS: Of 167 patients approached, 58 were excluded because they could not communicate in spoken English, and 4 refused to participate. Of the remaining 105 patients, 17 (16%) knew about living wills, 12 (11%) about durable powers of attorney for health care and 4 (4%) about advance directives. Twenty-three (22%) had thought about their preferences for life-sustaining treatment, 20 (19%) had discussed them, none had written them down, and 45 (43%) had thought about choosing a proxy. Sixty-one (58%) wanted to think about their preferences for treatment, 65 (62%) wanted to discuss them, 32 (30%) wanted to write them down, and 80 (76%) wanted to choose a proxy. The perceived barriers to completing an advance directive were inability to write, the belief that an advance directive was unnecessary, a fatalistic attitude, previous discussion of preferences, a desire to leave the decision to doctors, uncertainty about preferences, a desire to discuss preferences rather than document them, a desire to wait until the situation arose, a desire to write down preferences in the future and a desire to avoid thinking about preferences or advance directives. Respondents with more knowledge of life-sustaining treatments were more likely to want to complete an advance directive. CONCLUSIONS: Outpatients have positive attitudes toward advance directives, but their knowledge and experience are limited. These data underscore the need for patient education and for policies to eliminate the barriers to completing advance directives that patients face.