The influence of urban land use on seed dispersal and wetland invasibility

Urban habitats are generally considered highly invaded by exotic species due to the frequency and extent of disturbance caused by human activities and development. Our previous study had demonstrated that forested wetlands within residential areas are more extensively invaded than wetlands within industrial–commercial areas. In this study, we investigate whether the structure of the forest edge and seed dispersal can explain the differential in the invasion of wetlands surrounded by industrial and residential land use. Our results indicate that edges of industrially bordered wetlands are denser, with vegetation concentrated at the boundary of tree growth, whereas the edges of residentially bordered wetlands are more open and diffuse. This difference influences the number of seeds and species capable of dispersing into the wetland. Less dense edges resulted in a higher number of seeds entering residential wetlands; however, there were no differences in the numbers of exotic seeds or exotic species in the seed rain residential and industrial wetlands. Although seed dispersal could not directly explain differences in the current extent of invasion of these sites, seed dispersal did follow corridor pathways, including ditches and trails that breach the edges and extend through the wetlands. These disturbances act as corridors for seed dispersal into both types wetlands and may play a role in introducing new species to the interior of the wetland, an outcome supported by a higher number of exotic species in the seed banks of residential sites. Our results suggest that both the type of adjoining land use and the provision of access to people on trails in urban wetlands can affect the composition of these communities.     

Cytoplasmic and nuclear pyrimidine ribonucleotide pools in HeLa cells

A comparison of the rate of approach to equilibrium U:C labeling for two species of RNA whose base composition is known has been described previously as a method to determine the similarity or difference in the pyrimidine ribonucleotide pools from which the RNA species are synthesized. The procedure is now utilized to examine the pools used for the synthesis of HeLa cell nuclear RNA, mitochondrial RNA and poliovirus RNA. The results indicate that poliovirus RNA molecules derive from a pyrimidine precursor pool indistinguishable from that used for the synthesis of both heterogeneous nuclear RNA and 45 S ribosomal RNA in the nucleus, but that a separate and distinct pool is used for the synthesis of mitochondrial RNA. In addition, a comparison of the radioactivity ultimately found in UMP and CMP in a single species of RNA labeled in the presence or absence of actinomycin D shows that the conversion of uridine to cytidine nucleotides is significantly slowed in the presence of the drug. Direct measurement of the ratios of radioactivity in these RNA precursors in the acid-soluble pool confirm this observation.     

In Vitro Synthesis of Proteins by Membrane-Bound Polyribosomes from Vesicular Stomatitis Virus-Infected HeLa Cells

Membrane-bound polysomes from vesicular stomatitis virus (VSV)-infected HeLa cells synthesize predominantly three proteins in an in vitro protein synthesizing system. These three proteins have different molecular weights than the viral structural proteins, i.e., 115,000, 88,000, and 72,000. Addition of preincubated L or HeLa cell S10 or HeLa cell crude initiation factors stimulates amino acid incorporation and, furthermore, alters the pattern of proteins synthesized. Stimulated membrane-bound polysomes synthesize predominantly viral protein G and lesser amounts of N, NS, and M. In vitro synthesized proteins G and N are very similar to virion proteins G and N based on analysis of tryptic methionine-labeled peptides. Most methionine-labeled tryptic peptides of virion G protein contain no carbohydrate moieties, since about 90% of sugar-labeled peptides co-chromatograph with only about 10% of methionine-labeled peptides. Sucrose gradient analysis of the labeled RNA present in VSV-infected membrane-bound polysomes reveals a relative enrichment in a class of viral RNA sedimenting slightly faster than the total population of the 13 to 15S mRNA, as compared to a VSV-infected crude cytoplasmic extract. A number of proteins, other than the viral structural proteins, are synthesized in the cytoplasm of five lines of VSV-infected cells. One of these proteins has the same molecular weight as the major in vitro synthesized protein, P(88). In vitro synthesized protein P(88) does not appear to be a precursor of viral structural proteins G, N, or M based on pulse-chase experiments and tryptic peptide mapping. Nonstimulated membrane-bound polysomes from uninfected HeLa cells synthesize the same size distribution of proteins as nonstimulated VSV-infected membrane-bound polysomes.     

Reduction of Visceral Adipose Tissue and Improvement of Metabolic Indices: Effect of Dexfenfluramine in NIDDM

Increased visceral adipose tissue is thought to contribute to impaired glucose tolerance. We studied 10 men with non-insulin dependent diabetes (NIDDM) before and after a 12-week intervention study using dexfenfluramine. Subjects had a mean body mass index (BMI) of 26.4 ± 1.7 kg\m² and had an abdominal distribution of body fatness (waist-to hip ratio >0.9). Anthropometric indices, biochemistry, macronutrient intake from 7-day food records as well as a euglycaemic glucose clamp and magnetic resonance imaging (MRI) were performed at week 0 and week 12. Abdominal adipose tissue area measured by MRI was reduced from 854 ± 270 cm² to 666 ± 231 cm² (p=0.003) due mainly to a selective 32% reduction in visceral fat area from 484 ± 230 cm² to 333 ± 72 cm² (p=0.002). Insulin sensitivity improved from 0.29 ± 0.13 [min^?1 (mU/L)] to 0.54 ± 0.21 [min^?1 (mU/L)] (p=0.01) and C-peptide levels reduced from 0.77 ± 0.24 μmol/L to 0.58 ± 0.15 μmol/L (p=0.002). The reductions in fasting glucose and glycated haemoglobin failed to achieve significance. Fasting total cholesterol and triglyceride levels significantly reduced (p=<0.001 and p=0.021 respectively). There was a reduction in total energy intake (p=0.005) due to a significant reduction in calories obtained from fat (p<0.001). Thus dexfenfluramine was shown to be a useful adjunct therapy for the reduction of visceral fat in abdominally-obese men with NIDDM with an associated improvement in insulin sensitivity.     

Knowledge and attitudes toward human cloning in Israel

The success of mammal cloning in 1997 has brought the issue of human cloning into public discussion. Human cloning has several aspects and potential applications for use in both reproductive and non-reproductive matters. The aim of this study was to evaluate the knowledge and attitudes toward human cloning in Israel. Data from 120 respondents (68 health professionals and 52 non-health professionals), all Jewish, Hebrew speaking with at least 15 years of education each, were collected using two questionnaires that dealt with knowledge and attitudes toward human cloning. Results showed that although health professionals had significantly more knowledge that non-health professionals, all respondents had poor knowledge about cloning. No difference in attitudes was found between the groups. Most respondents opposed human cloning, but more positive attitudes toward non-reproductive cloning were found. The results are discussed in the context of the deficit model. The findings indicate a need to provide information about human cloning to allow people to form their attitudes based on factual knowledge.