Cultivation can increase harvesting pressure on overexploited plant populations.

Captive breeding and cultivation of overharvested species is frequently proposed as a conservation strategy, yet there is little evidence under what conditions, if at all, the strategy is effective. We created a bioeconomic model to investigate the socioeconomic conditions favoring cultivation over wild harvesting and likely impacts on the wild population. We parameterize the model with the case study of illegal xaté palm (Chamaedorea ernesti-augusti) harvesting in Belize and Guatemala. We examine how changes in law enforcement, a price premium for cultivated leaf, land ownership, and alternative income might affect decisions to cultivate and the impact of cultivation on wild populations. We show that those switching to cultivation are largely not wild harvesters because of barriers such as land ownership. We also find that if harvesters do switch to cultivation, they may have a negative effect on the wild population through harvesting of material to set up plantations. We found increasing alternative income reduces harvesting pressure and suggests the provision of alternative livelihoods would more directly reduce pressure on the wild population. Although schemes to encourage cultivation seem an appealing conservation intervention, we urge caution in assuming that people will readily adopt cultivation of wild harvested species or that this would necessarily reduce impacts on wild populations.

QTLs associated with root traits increase yield in upland rice when transferred through marker-assisted selection.

Altering root morphology of rice (Oryza sativa L.) cultivars could improve yields in drought-prone upland ecosystems. Marker-assisted backcross breeding was used to introgress four QTLs for root traits into an upland rice cultivar. The QTLs had previously been identified under experimental conditions in a different genetic background. The introgressed lines and the recurrent parent were grown for 6 years by resource-poor farmers in upland sites in Eastern India and yields recorded. In combination the QTLs significantly increased yield by 1 t ha(-1) under relatively favourable field conditions. In less favourable trials, the QTL effects were not detected due to greater heterogeneity in soil-water availability in very low yielding environments and consequent yield variability. Root studies under controlled conditions showed that lines with the introgressions had longer roots throughout tillering than the recurrent parent (14 cm longer 2 weeks after sowing). Therefore, both improved roots and increased yield can be attributed to the introgression of QTLs. This is the first demonstration that marker-assisted backcross breeding (MABC) to introgress multiple root QTLs identified under controlled conditions is an effective strategy to improve farmers' yields of upland rice. The strategy was used to breed a novel upland rice cultivar that has been released in India as Birsa Vikas Dhan 111.

In vitro inactivation of mammalian methionine synthase by nitric oxide.

The research described here provides one mechanism of uniting current effects of nitric oxide (NO) with the elevated levels of homocysteine detected in patients with cardiovascular and other disease. Time- and dose-dependent studies of the inhibition of purified mammalian methionine synthase by NO were performed. The in vitro study gave an effective IC50 value of 3 mu mol L-1. Methionine synthase converts cellular homocysteine to methionine and is a major enzyme in the biosynthetic pathways for folates, S-adenosylmethionine and biological methylations, sulphur amino acids and polyamines. Nitric oxide-induced inactivation of methionine synthase alters the levels of these metabolites and could therefore provide a connection between the cardiovascular effects of NO, the plasma homocysteine levels and cardiovascular diseases that is complementary to the more traditional NO-induced stimulation of guanylate cyclase and the convertion of homocysteine to oxidized sulphur amino acids.

Correlation of nonstressed fetal heart rate with sequential contraction stress test.

Two hundred seven high-risk patients were studied prospectively by standardized nonstressed fetal heart rate monitoring followed immediately by contraction stress testing (CST). Of the 604 combined procedures examined, 90.2% of nonstress tests (NST) were interpreted as reactive; none was associated with a positive CST. Of the nonreactive NSTs, 37% were followed by positive CSTs. These data support the contention that a reactive NST performed in compliance with a standard protocol is unlikely to be associated with a positive CST.

Amniotic fluid phosphatidylglycerol and phosphatidylinositol separated by stepwise-development thin-layer chromatography.

We describe a stepwise-development thin-layer-chromatographic technique for separating phosphatidylglycerol and phosphatidylinositol in samples of amniotic fluid. Plates are prepared from silica gel G slurried in a 50 g/L ammonium sulfate solution. Phospholipid phosphorus determination is not needed. Phospholipid phosphorus determination is not needed. Phosphatidylglycerol and phosphatidylinositol, measured densitometrically, are expressed as ratios to the sphingomyelin present. These ratios are correlated with the lecithin/sphingomyelin ratio and age of gestation in normal and abnormal pregnancies.

In vitro biosynthesis of TSH- and LH-releasing factors by the human placenta.

Human chorionic membrane and human placental tissue contain substances with the same elution volume as hypothalamic TRF and LRF standards during separation by carboxyl-methyl-cellulose ion-exchange chromatography. Homogenates prepared from fresh human placentas delivered at term caused release of TSH (thyroid-stimulating hormone) and LH (luteinizing hormone) when bioassayed in rats. After dialysis of placental homogentes, synthesis of biologically active TSH-and LH-releasing factors can be shown to occur in vitro following the addition of appropriate precursor amino acids and cofactors.