Dalea

Abstract: Potential sources of fixed nitrogen in a Colorado desert environment were examined by the acetylene reduction method at the Deep Canyon Desert Research Center, near Palm Desert, California. In field and greenhouse studies all members of the genera Astragalus, Dalea, Lotus, Lupinus, Melilotus, and Prosopis examined formed active nodules (acetylene reduction) with indigenous soil bacteria. No evidence of nodulation was found forAcacia greggii, Cercidiumfloridum, orHoffmannseggia microphylla. Lotus tomentellus was estimated to fix 0.1 kg N ha-1 by the time of flowering under field conditions. Several members of the genus Dalea showed substantial rates of acetylene reduction in the greenhouse: D. emoryi, 16.1 + 3.5, D. mollissima, 11.4 + 3.7, D. schottii 2.9 + 1.7, D. spinosa 2.5 + 0.4 ,moles ethylene plant-' hr -1. In greenhouse assays where water was supplied continuously, blue-green algal-lichen crusts reduced acetylene at an average rate of 11.0 + 5.7 nmoles ethylene cm-2 hr-1 with a maximum of 57.1. But when in situ assays were done following irrigation of a field plot with 2.3 cm of water, much lower activities were observed with a maximum activity of only 6.4 nmoles cm-2 hr-1.

Abstract: A study of the diversity of legumes in the northern part of the state of Nuevo Leon was undertaken. 38 genera, 94 species and 26 infraspecific taxa of legumes were recorded. The family Fabaceae comprises 18 genera and 42 species, Mimosaceae 10 and 30 and Caesalpiniaceae 10 and 22 respectivelly. The genera with highest number of species are Acacia (12), Dalea (10), Mimosa (6), Senna (5), Caesalpinia (4) and Bauhinia (4). Shrubby legumes are the most abundant in the zone, representing 47% (46 species); the herbaceous ones constitute 46% (45) and the arboreal ones comprise 7% (7). The highest number of taxa was recorded on semithorn shrubland (52) piedmont scrub (48), oak-pine forest (44), while the mezquite shrublands shelter the lowest number of species (23).

Abstract: New potential treatments for disseminated fungal infections are needed, especially for infections caused by the commonly drug-resistant pathogens Candida albicans and C. glabrata. These pathogens cause systemic candidiasis, a significant cause of mortality in immune-compromised patients. ABC transporters of the pleiotropic drug resistance subfamily, such as Cdr1p of C. albicans, play an important role in antifungal resistance and are potential bioassay targets for antifungal therapies against drug-resistant pathogens. We observed strong antifungal growth inhibitory activity in the methanol extract of Dalea formosa roots. This extract afforded six new isoflavonoids, sedonans A-F (1-6), a new but-2-enolide, 4'-O-methylpuerol A (7), and the new pterocarpan ent-sandwicensin (8). The structures and absolute configurations of these compounds were assigned using spectroscopic and chiroptical techniques. The direct antifungal activity of 1 against C. glabrata (MIC = 20 μM) was higher than that of fluconazole. Sedonans A-F and ent-sandwicensin were also active against Saccharomyces cerevisiae strains that express differing ABC transporter-associated resistance mechanisms but differed in their susceptibility to Cdr1p-mediated detoxification. A sedonan A (1)/ent-sandwicensin (8) combination exhibited synergistic growth inhibition. The results demonstrate that multiple crude extract compounds are differentially affected by efflux-mediated resistance and are collectively responsible for the observed bioactivity.