Population Genetic Structure of Phytophthora infestans in Ecuador.

ABSTRACT The population genetic structure of Phytophthora infestans in Ecuador was assessed from 101 isolates collected from 1990 to 1992 and 111 isolates collected in 1993. All isolates were analyzed for mating type and allozyme genotype. Both samples were dominated (>95%) by a clonal lineage (EC-1) defined from neutral markers: 90/100 genotype for glucose-6-phosphate isomerase, 96/100 genotype for peptidase, A1 mating type, and a previously unreported nuclear DNA fingerprint. The remaining isolates belonged to the US-1 clonal lineage, which has a worldwide distribution. Isolates in the 1993 sample were analyzed for virulence and metalaxyl sensitivity. All representatives of EC-1 had complex patho-types, with three pathotypes representing >60% of the collection. There was variation for metalaxyl sensitivity. There was no evidence for geographical substructuring on the basis of neutral markers, but there was evidence for limited substructuring based on metalaxyl sensitivity and specific virulence. We hypothesize that EC-1 has been recently introduced to Ecuador.

Disadvantaged women and smoking.

High rates of smoking are found among disadvantaged women, and there is a demand for cessation interventions specifically targeted to meet their needs. This project used a number of information sources to examine the factors associated with these women's smoking behaviours and the potential barriers and supports to cessation. Few of the women-centred cessation programs whose representatives were contacted were appropriate for, or available to, disadvantaged women in Canada. Interviews with 386 disadvantaged women revealed that their smoking was intimately linked with their life situation of poverty, isolation and caregiving; smoking was a mechanism for coping with the stress of their lives. Agencies outside traditional tobacco control organizations, such as women's centres, were well positioned to initiate or expand services that support smoking cessation for these women and were trusted by the women who used their services. The findings have implications for programs, research and policy.

Smoking among disadvantaged women: causes and cessation.

This study aimed to identify social-psychological factors associated with smoking and smoking cessation among disadvantaged women. Individual and group interviews were conducted with disadvantaged women in Atlantic Canada. Participants were predominantly poor, unemployed, geographically isolated, and single parents. The factors associated with smoking included coping with stresses, loneliness, powerlessness, low self-efficacy, social pressures, and addiction. Support from peers (i.e., women in similar circumstances) and partners was considered important. Health professionals and traditional cessation programs were not perceived as supportive. Participants viewed women's centres and women's agencies as appropriate deliverers of cessation programs. Methodological issues are discussed.

Structure and properties of the rapidly sedimenting replicating complex of staphylococcal phage K DNA.

Rapidly sedimenting complexes (RSCs) of replicating phage K DNA, isolated by rate zonal centrifugation in sucrose gradients, contain bacterial membrane lipids and protein. During the first half of the latent period the number of DNA molecules in a RSC increased from 1 to about 27. Digestion by Pronase caused the complexes to dissociate and release virion lengths of DNA which sedimented slowly like free mature DNA. RSCs treated with SDS disintegrated and released tangled DNA molecules, each about one virion length in size, but these structures retained their fast sedimentation characteristic. Chloramphenicol (CM) at 100 micrograms/ml did not completely inhibit complex formation or DNA replication, indicating that pre-existing host proteins were involved in these processes. CM reduced DNA replication by 50 to 80%. It is concluded that phage K DNA replicates attached to the cytoplasmic membrane of the host.

The morphology of staphylococcal bacteriophage K and DNA metabolism in infected Staphylococcus aureus.

The morphology and dimensions of bacteriophage K particles were determined by electron microscopy. This virus had an icosahedral head (approx. 70 nm diam.) and a long (210 nm) thin (15 nm) contractile tail which terminated in a complex basal appendage. The precise dimensions of the particles were dependent on the negative stain employed. The buoyant densities of the K virus particle and its DNA were 1 X 479 g/ml and 1 X 689 g/ml respectively. The DNA had a base composition of 30% G + C, a contour length of 16 X 1 micron and a calculated mol. wt. of 33 X 10(6). With Staphylococcus aureus (NCTC 9318) as host, the latent period was 25 min, the eclipse period 14 min and the average burst size 60 p.f.u./bacterium. Infection resulted in inhibition of host DNA synthesis and degradation of the bacterial DNA: the products were used for tee synthesis of phage DNA. The kinetics of DNA synthesis is infected and uninfected bacteria were examined. There was no initial cessation of DNA synthesis in the infected bacteria.