Quantitation of fourteen urinary alpha-amino acids using isobutane gas chromatography chemical ionization mass spectrometry with 13C amino acids as internal standards

Isobutane chemical ionization gas chromatography mass spectometry of the N-trifluoroacetyl-carboxy-n-butyl ester derivatives of amino acids, using a commercial per-13C-amino acid mixture as internal standards, provided a sensitive and specific method for quantitative analysis of fourteen urinary alpha-amino acids. A computer controlled quadrupole mass spectrometer was used in a selected ion monitoring mode to record the ion current due to the protonated molecular ions of each alpha-amino acid/13C analogue pair. BASIC programmes located peak maxima, and using previously established standard curves, calculated the amino acid content on the bases of both peak height and peak area ratios. Duplicate amino acid analyses are possible on 5 microliter of urine. Instrumental analysis required 25 minutes, automated data processing 10 minutes, and sample preparation 2 hours. Detection limits approached 1 ng with a typical mean standard deviation of 2% for the instrumental analysis.     

Wetlands of Sub-Saharan Africa: distribution and contribution of agriculture to livelihoods

Wetlands contribute in diverse ways to the livelihoods of millions of people in Sub-Saharan Africa. In many places they are inextricably linked to cropping and livestock management systems. At the same time, increasing population in conjunction with efforts to increase food security is escalating pressure to expand agriculture within wetlands. The environmental impact of wetland agriculture can, however, have profound social and economic repercussions for people dependent on ecosystem services other than those provided directly by agriculture. Currently, the basis for making decisions about the extent to which wetlands can be sustainably used for agriculture is weak. This paper provides an overview of wetland distribution, type and condition across Sub-Saharan Africa. Findings from an investigation of wetland use conducted in Tanzania are presented. These highlight the reliance of communities on both wetland agriculture and natural resources, and show that the nature of household dependence varies significantly from place to place and as socio-economic status changes. Consequently, incentives to manage wetland resources will differ markedly, not only from one location to another, but also across socio-economic groups within the same community. This complexity highlights the need for critical analysis of the social and economic factors that underpin the dynamics of wetland resource use in the development of sustainable management plans.     

SURVIVAL OF AN UNIRRADIATED SALMONELLA TYPHIMURIUM MARKER STRAIN INOCULATED IN POULTRY FEEDS AFTER IRRADIATION

The present study was designed to compare unirradiated Salmonella typhimurium survival during storage after inoculation in either irradiated or unirradiated poultry feed. The effects of irradiation (5 kGy) on the indigenous feed microflora and on the survival of marker strain of S. typhimurium contaminated after irradiation treatment were determined during 56 days of storage of either soybean meal (SBM) or meat and bone meal (MBM) based feeds. The initial aerobic bacterial populations were reduced more than 90% in both SBM (4.96 to 4.08 ± 0.03 log₁₀ CPU/g feed) and MBM (5.12 to 3.90 ± 0.03) by irradiation. Irradiation treatment reduced the average fungal counts during 56 days of storage in both SBM (4.24 to 2.74 ± 0.03) and MBM (4.38 to 2.15 ± 0.03) containing feeds. However, unirradiated S. typhimurium populations inoculated after irradiation of the feed were not different in either irradiated or nonirradiated SBM and MBM based feeds. Therefore, the differences in fungal versus bacterial sensitivity among the feed types and storage times suggests that gamma irradiation can alter the makeup of indigenous microbial populations in feed but this does not appear to have a discernible influence on subsequent survival of unirradiated S. typhimurium added as a dry inoculum after irradiation.     

Reproductive patterns of selected understorey trees in the Malaysian rain forest: the sexual species

HA, C. O., SANDS, V. E., SOEPADMO, E. & JONG, K., 1988. Reproductive patterns of selected understorey trees in the Malaysian rain forest: the sexual species. Investigations were carried out on the floral, fruit and seed biology, and the embryology of representatives of the Sapindaceae and Bombacaceae which occur in the lower canopy of the lowland rain forest of Peninsular Malaysia. Pollination studies indicated cross-compatibility and outbreeding in all species examined, associated with self-compatibility in the polygamous monecious Pometia pinnata and Allophylus cobbe and, to a limited extent, in the effectively dioecious Xerospermum intermedium . In these sapindaceous species, together with the self-incompatible androdioecious Nephelium lappaceum , the structurally hermaphrodite flowers were determined embryologically to be functionally female with no anther dehiscence. The self-incompatible Durio griffithii of the Bombacaceae, and X. intermedium, N. lappaceum and P. pinnata were shown by embryological studies to form a sexual zygote. The observations on these outcrossing species are considered in relation to their potential for gene exchange and their contribution to the maintenance of species diversity in the lowland rain forest.