An indigenous plant food used by lactating mothers in west Africa: the nutrient composition of the leaves of Kigelia africana in Ghana.

Although the leaves of Kigelia africana are used to make a palm-nut soup which is consumed mainly by lactating women in many parts of sub-Saharan Africa, little is known about the nutrient qualities of this underutilized and underappreciated plant food. Leaves of Kigelia africana, called "sausage tree" in English and "nufuten" in the Twi language of Ghana, were collected in Kumasi and analyzed for their content of nutritionally important fatty acids, amino acids, minerals, and trace elements. The dried leaves contained 1.62% fatty acids, of which α-linolenic acid and linolenic acid accounted for 44% and 20%, respectively, of the total. Protein accounted for 12.6% of the dry weight and, except for lysine, its overall essential amino acid profile compared favorably to a World Health Organization protein standard for school children. Kigelia leaf contained considerable amounts of many essential elements, including calcium (7,620 µg/g), iron (161 µg/g), magnesium (2,310 µg/g), manganese (14.6 µg/g), zinc (39.9 µg/g), and chromium (0.83 µg/g); selenium, however, was not detected. These data indicate that Kigelia africana leaf compares favorably with many other commonly-consumed green leafy vegetables such as spinach and provides a rational basis for promoting the conservation and propagation of the plant and encouraging its wider use in the diets of populations in sub-Saharan Africa.

Repair replication and photorepair of DNA in larvae of Drosophila melanogaster.

Repair replication of DNA has been studied in first instar larvae of Drosophila melanogaster with isopycnic centrifugation techniques. Larvae were fed BUdR, FUdR, streptomycin, penicillin, and Fungazone for two to four hours prior to exposure to UV, X-rays, MMS, or EMS. Feeding was continued for four hours in the presence of (3)HBUdR and DNA was isolated from whole larvae. Repair replication is stimulated by each of these agents. MMS is about 10 times as potent as EMS in stimulating repair synthesis. A dose of 200 ergs/mm(2) largely saturates the level of repair replication observed after UV irradiation. Repair replication rises between 0 and 80,000 R of X-rays before falling off. Semiconservative synthesis is seriously inhibited above a dose of 40,000 R of X-rays. Photorepair has been detected as a reduction in repair synthesis resulting from post-irradiation exposure to photoreactivating light. The same treatment has no detectable effect on X-ray-stimulated repair replication. Repair replication is insensitive to the presence of caffeine or hydroxyurea during the final incubation, although semiconservative synthesis is strongly inhibited by these agents. A mixture of BUdR and (3)HTdR can be used to replace (3)HBUdR in detecting repair replication.

Identification of a second locus in Drosophila melanogaster required for excision repair.

The mus(2)201 locus in Drosophila is defined by two mutant alleles that render homozygous larvae hypersensitive to mutagens. Both alleles confer strong in vivo somatic sensitivity to treatment by methyl methanesulfonate, nitrogen mustard and ultraviolet radiation but only weak hypersensitivity to X-irradiation. Unlike the excision-defective mei-9 mutants identified in previous studies, the mus(2)201 mutants do not affect female fertility and do not appear to influence recombination proficiency or chromosome segregation in female meiocytes.--Three independent biochemical assays reveal that cell cultures derived from embryos homozygous for the mus(2)D1 allele are devoid of detectable excision repair. 1. Such cells quantitatively retain pyrimidine dimers in their DNA for 24 hr following UV exposure. 2. No measurable unscheduled DNA synthesis is induced in mutant cultures by UV treatment. 3. Single-strand DNA breaks, which are associated with normal excision repair after treatment with either UV or N-acetoxy-N-acetyl-2-aminofluorene, are much reduced in these cultures. Mutant cells possess a normal capacity for postreplication repair and the repair of single-strand breaks induced by X-rays.

Attomole level protein sequencing by Edman degradation coupled with accelerator mass spectrometry.

Edman degradation remains the primary method for determining the sequence of proteins. In this study, accelerator mass spectrometry was used to determine the N-terminal sequence of glutathione S-transferase at the attomole level with zeptomole precision using a tracer of (14)C. The transgenic transferase was labeled by growing transformed Escherichia coli on [(14)C]glucose and purified by microaffinity chromatography. An internal standard of peptides on a solid phase synthesized to release approximately equal amounts of all known amino acids with each cycle were found to increase yield of gas phase sequencing reactions and subsequent semimicrobore HPLC as did a lactoglobulin carrier. This method is applicable to the sequencing of proteins from cell culture and illustrates a path to more general methods for determining N-terminal sequences with high sensitivity.