Physical properties of myosin from aortic smooth muscle.

Porcine aortic myosin is a smooth muscle contractile protein similar to its striated muscle counterpart. Electrophoresis in sodium dodecyl sulfate indicates that the molecule consists of three classes of subunits with polypeptide chain molecular weights of 192,000, 19,000, and 15,000. At 277 nm the absorption spectrum gives an extinction coefficient for aortic myosin of 0.558 cm2/mg; the circular dichroism spectrum of the protein indicates that aortic myosin contains about 70% of its residues in the alpha-helical configuration. Amino acid analysis shows that the smooth muscle myosin has significantly more arginine and leucine and significantly less valine and isoleucine than rabbit skeletal muscle myosin. Other studies yielded these data: Vapp = 0.716 mL/g [eta] = 0.213 mL/mg, S20, w = 5.84 x 10(-13)S. Similar studies with rabbit skeletal muscle myosin indicate that Vapp = 0.711 mL/g and S20, w = 6.36 x 10(-13)S. These properties suggest that aortic myosin, like skeletal muscle myosin, behaves hydrodynamically like a rigid rod.     

Decline in measles mortality: nutrition,age at infection,or exposure?

The mortality from measles was studied in an urban area of Guinea-Bissau one year before and five years after the introduction of a vaccination programme. The years after the introduction of immunisation saw a decline in mortality among unvaccinated children with measles. This decline occurred despite a lower age at infection and an increasing prevalence of malnourished children. State of nutrition (weight for age) did not affect the outcome of measles infection. The incidence of isolated cases, however, increased in the period after the introduction of measles vaccination. As mortality was lower among these cases, diminished clustering explained some of the reduction in mortality. Comparison between the urban district and a rural area inhabited by the same ethnic group showed a lower age at infection, less clustering of cases, and lower case fatality ratios in the urban area.Endemic transmission of measles in urban districts leads to less clustering of cases, which may help explain the usually lower case fatality ratios in these areas. As measles vaccination increases herd immunity and diminishes clustering of cases, it may reduce mortality even among unvaccinated children who contract the disease.     

Floral scent in dioeciousSalix (Salicaceae)—a cue determining the pollination system?

Floral scents of male and female inflorescences of three dioeciousSalix species were collected by head-space adsorption, and analysed by GC-MS. InSalix caprea andS. cinerea 1,4-dimethoxy benzene was the main compound, and male and female scents showed a high degree of resemblance. No dominant compound was found inS. repens and malefemale scent similarity was low. Floral scent inSalix is likely a strong orientation cue, guiding pollinators between male and female plants ensuring pollen transfer and pollination. We suggest that a high degree of male-female floral scent resemblance is coupled to a high degree of insect pollination. Floral scent does not promote reproductive isolation betweenS. caprea andS. cinerea.     

Iodoazomycin riboside (1-(5'-iodo-5'-deoxyribofuranosyl)-2-nitroimidazole), a hypoxic cell marker. I. Synthesis and in vitro characterization

Misonidazole (MISO), a selective radiosensitizer of hypoxic cells, forms adducts with cellular biomolecules with rates which are 30-50 X higher under hypoxic as compared to aerobic conditions of incubation. This technique of sensitizer adduct formation was proposed as a possible means of measuring the hypoxic fraction of solid tumors by noninvasive procedures. Iodoazomycin riboside (5'-IAZR) and 5'-[125I]AZR were synthesized and chemically characterized. Measurements of in vitro cytotoxicity and radiosensitizing ability with EMT-6 tumor cells in vitro indicated that 5'-IAZR is approximately 3 X more toxic and effective than is azomycin riboside (AZR) and approximately 10 X more toxic and effective than is MISO. 5'-[125I]AZR was shown to selectively bind to hypoxic EMT-6 cells at rates which were 2.5-3 X faster than those of MISO. The absolute rates of binding of 5'-IAZR to hypoxic cells at concentrations of 10-100 microM are the highest observed in this laboratory for any hypoxic cell radiosensitizer tested to date. These data suggest that 5'-IAZR, when labeled with an appropriate radioisotope (e.g., 131I), might be a useful marker for hypoxic cells in solid tumors amenable to noninvasive detection. Additional studies with animal tumor models appear to be warranted.     

Floral scent variation in the Pyrola rotundifolia complex in Scandinavia and Western Greenland

The variation in floral scent composition within and among populations of four taxa belonging to the Pyrola rotundifolia complex was analyzed using Principal Component Analysis. Two major groups were recognized, P. norvegica and P. grandiflora on the one side and P. rotundifolia s. str. on the other. Benzaldehyde dominated the scent of the first group and methoxy benzenes and phenyl propanoids that of the second group. A large variation in the floral scent chemistry was found both within some of the studied populations as well as among them. The floral scent composition of P. rotundifolia ssp. maritima was no more different from P. rotundifolia ssp. rotundifolia , than the differences between populations of P. rotundifolia ssp. rotundifolia . The findings are in partial agreement with the current delimitation of the taxa in the P. rotundifolia complex.     

Hybridization between Taeniatherum caput-medusae and Triticum aestívum (Poaceae)

Hybrid plants were obtained in an intergeneric cross between Taenìatherum caputmedusae (2n = 2x = 14) and Triticum aestívum (2n = 6x = 42). The chromosome number was as expected 2n = 28. Morphologically the offspring looked like Triticum aestívum . Analysis of meiotic metaphase I showed an unexpected high number of bi- and trivalents which is ascribed to homoeologous pairing of chromosomes from T. aestivum . It is concluded that the genome of Taeniatherum has effects on the pairing regulation system present in T. aestívum .     

DNA markers for downy mildew resistance genes in sorghum.

The random amplified polymorphic DNA technique was used to find markers for a downy mildew resistance gene in sorghum. Of the 674 random primers screened for polymorphism, 2 amplified fragments were linked to a downy mildew resistance gene in sorghum line SC414. Utilization of an existing restriction fragment length polymorphism mapping population (IS3620C x BTx623) also revealed two markers that are linked to a different resistance gene in another sorghum line, BTx623.     

Conversion of cephalosporin-c into 7-phenoxy-acetamido-cephalosporanic acid by acyltransferase of mutants of Penicillium chrysogenum

Summary We have tested the acyl-transferase of penicillin producing strains and penicillin-less mutants of Penicillium chrysogenum for their ability to exchange the d--aminoadipic acid side chain of cephalosporin-C with phenoxyacetic acid. We found the reaction in both types of strains.     

Vegetation types and patterns in Senegal based on multivariate analysis of field and NOAA-AVHRR satellite data

Abstract. Woody vegetation was studied in 44 sites in Senegal. Species composition and density were analysed with TWINSPAN and Canonical Correspondence Analysis; 16 vegetation types were defined. A supervised, multispectral and multitemporal classification of day and night, dry season NOAA-AVHRR imagery was used to identify their distribution with a classification accuracy ranging from 60–100%.