Sixteen SSR markers were used to identify genetic relationships of 43 coconut accessions conserved ex-situ in field gene banks of the Coconut Research Institute of Sri Lanka (CRISL). The 16 SSR markers clearly unveiled the genetic relationships of Sri Lankan coconut populations. Gene diversity and polymorphism information content (PIC) were relatively higher in the common 'tall' coconut and Pacific tall coconut than in autogamous dwarf form of coconut. The SSR assessment unveiled the genetic lineages based on evolutionary mechanisms signifying the narrow genetic base of coconut germplasm, with most of the diversity confining to 'tall' coconut. The main genetically different coconut groups identified were 'tall', 'San Ramon and alike' and 'dwarf'. These have already been utilised in coconut improvement programmes and the study emphasizes the need for enrichment of the gene pool by exotic introductions. The overall results also supports the hypothesis that coconut disseminated from it's center/s of origin in far east to Indo Atlantic regions via America.

Strains of Escherichia coli isolated from persons with dysentery-like diarrheal disease were demonstrated to adhere to the surface of cultured HEp-2 (human epithelial) cells under conditions that removed nonpathogenic control bacteria and to cause hemagglutination of human red blood cells. The plasmid content of 13 stains surveyed was found to be variable with respect to resistance to antibiotics and the presence of small cryptic plasmids. Conjugal transfer to resistance plasmids from two of the clinical isolates to a number of nonpathogenic laboratory and field isolates of E. coli was not accompanied by transfer of the capacity either for specific interaction with cultured HEp-2 cells or for hemagglutination of human red blood cells. Furthermore, cured derivatives of the enteroinvasive strains retained positive reactions in the assay systems.

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Data are presented suggesting that the most critical factor determining whether an Hfr dnaAts strain can synthesize deoxyribonucleic acid and form colonies at temperatures that are nonpermissive for corresponding F- strains is neither the site of insertion of F nor the presence of additional mutations in the F particle or the chromosome; it is whether the particle is capable of autonomous replication at the temperature used. Consequently, suppression of the DnaA phenotype in Hfr strains occurs at 40 C but not, in most of them, at 42 C without the occurrence of additional mutations. The site of insertion of F may also be important since it is shown that in one Hfr dnaA strain partial suppression does occur at 42 C. In addition, it is shown that strains exhibiting suppression by integration of F at 40 C on minimal agar plates do not do so at this temperature on nutrient agar plates.

Three highly repetitive DNA sequences Rp36, Rp217 and Rp234, have been isolated from Anopheles culicifacies Giles sensu lato. The cloned DNA sequences were found at a higher copy number in species B and C, than in species A of the A. culicifacies complex. These sequences may therefore be used as DNA probes to distinguish species A from the other two species, using a 200-fold dilution of a single mosquito DNA extract in a dot-blot hybridization assay. Rp36 and Rp217 have been completely sequenced. Internal repeats were absent in Rp36. Two related core sequences of 13 and 16 bp were found tandemly repeated in Rp217. These probes enable the rapid detection of species A of A. culicifacies in field investigations.