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Most plant genes occur as members of multigene families where new copies arise through duplication. Duplicate genes that do not confer an adaptive advantage to the plant are expected to rapidly erode into pseudogenes owing to the accumulation of transpositions, insertion/deletion mutations and nucleotide changes. Nonfunctional copies will drift to fixation within a few million years and ultimately erode beyond recognition. Duplicate genes that are retained over longer periods of evolutionary time must be positively selected based on some adaptive advantage conferred on the plant species. We explore the dynamics of the recruitment of new duplicate genes for chalcone synthase, the enzyme that catalyzes the first committed step of flavonoid biosynthesis, and for the myb family of transcriptional activators. Our analyses show that new chs genes are recruited into the genome of grasses at a rate of one new copy every 15 to 25 million years. In contrast, the myb gene family is much older and many duplicate copies appear to predate the separation of the angiosperm lineage from other seed plants. The general pattern suggests a rapid adaptive proliferation of new chs genes but a more ancient elaboration of regulatory gene functions. Our analyses also reveal accelerated rates of protein evolution following gene duplication and evidence is presented for interlocus exchange among duplicate gene loci.

In this nonenzymatic colorimetric method, dichlorobenzoquinone chloroimine is used as a color reagent to measure uric acid in urine. This method is less subject to the interferences that make enzymatic methods unreliable and is inexpensive, simple, and fast.

The in vivo functioning of the urea cycle in the Rett syndrome (RS) was investigated using alanine load test. The test was carried out in girls with RS and their mothers. These results were compared with those on normal females, males and obligate carriers for ornithine carbamoyltransferase deficiency. Post load hyperammonaemia was not seen in any of the RS girls who were not on medication (valproate). Increased orotate excretion was found in some of the RS girls and mothers. The pattern of urinary excretion of orotate in RS girls and their mothers after a standardised alanine load was similar to that found in female carriers of OCT deficiency. This finding can be explained by a mutant OCT, subject to the Lyon effect, and linked to the gene abnormality in RS or by the presence of an abnormal X-linked mitochondrial protein synthesised in cytoplasma and positioned in close proximity to OCT. Such a protein abnormality could also affect mitochondrial functions in other cells, e.g. in the developing brain.

Two newborn infants, male (A) and female (B), with lethal hyperammonaemia are described in the same family. In both, symptoms started on the second day of life. Lethargy and hypotonia were the most prominent initial findings and were followed by convulsions and coma. In both, blood ammonia levels rose to 570 mumol/u (795 microgram/100 ml) a few hours before death, which occurred on the third and fourth day of life respectively. Assay of liver urea cycle enzymes in baby B showed a complete absence of mitochondrial carbamyl phosphate synthetase activity.

The effect of hydrocortisone or Panax ginseng, and/or a combination of hydrocortisone and Panax ginseng on phytohaemagglutinin (PHA-P)-induced transformation of peripheral blood lymphocytes were studied in 4 normal healthy adult volunteers. Increasing concentrations of Panax ginseng 0.16-1.60 micrograms X ml-1 caused a dose-related inhibition of PHA-P transformation of lymphocytes. A combination of 500 micrograms X ml-1 hydrocortisone and 0.80 micrograms X ml-1 Panax ginseng produced a greater suppression of PHA-P stimulation than either drug used alone. This suggests that Panax ginseng has a steroid-like effect in vitro, and may have a potentiating effect with hydrocortisone on T-cell-mediated immunity.

The clinical, radiological, and biochemical features of 2 male children with mannosidosis are described. Superficially they appeared to suffer from Hurler's syndrome, but the facies, eye signs, radiological and cytological features were atypical. Excess urinary oligosaccharides were found by thin-layer chromatography. The diagnosis was confirmed by determining the acidic alpha-mannosidase activity of leucocytes and cultured skin fibroblasts. Prenatal diagnosis is possible from cultured amniotic cells.