A highly polymorphic DNA marker linked to adult polycystic kidney disease on chromosome 16

Adult polycystic kidney disease (APCKD) is a common and often lethal multi-organ disease with an autosomal dominant pattern of inheritance; approximately 1 in 1,000 people carry the mutant gene. The major pathological abnormality is the development and progressive enlargement of cysts in several organs including the liver, pancreas and spleen as well as the kidneys. The basic biochemical defect which leads to the formation of cysts remains unknown. Cyst development, which is not retarded by any known therapy, leads to irreversible renal failure and death at a mean age of 51 unless dialysis or transplantation are used. Patients with the disease account for 9% of chronic dialysis requirement. The first symptoms tend to occur in the fourth decade, after most patients have reproduced. Presymptomatic diagnosis depends on the ultrasonographic detection of cysts, but exclusion cannot be achieved by this means; 34% of at-risk patients in the second decade and 14% in the third will go on to develop cysts after negative diagnosis. The low sensitivity of diagnostic techniques in this critical age-range imposes severe limitations on genetic counselling and the condition cannot be identified prenatally. Hence we have searched for a linkage marker for APCKD; we show here that the APCKD locus is closely linked to the alpha-globin locus on the short arm of chromosome 16 (zeta = 25.85, theta = 0.05).     

Lack of substrate specificity on the speed of amoeboid locomotion inNaegleria gruberi

Summary Comparison of locomotory rates ofNaegleria on glass, agar, plastic and fluorocarbon oil under a range of defined electrolyte concentrations showed the speed of amoeboid movement to be independent of the substrate's nature.Acknowledgments. We would like to thank Les Cooper for technical assistance, the Science Research Council for support and the 3M Company for the gift of FC75 oil.     

Cloned fragments of the plasmid ColV,I-K94 specifying virulence and serum resistance.

A cloned BamH1-generated fragment of ColV,I-K94 increased the virulence of Escherichia coli, causing an approximately 100-fold reduction in LD50 for chicks. A genetic determinant for resistance to the bactericidal effects of serum was mapped to a 5,300 base-pair sequence within the fragment. Neither colicin V nor immunity to colicin V affected the pathogenicity of E. coli for chicks.