Does Off-Farm Work Discourage Soil Conservation? Incentives and Disincentives Throughout Two Honduran Hillside Communities

   Soil conservation is widely regarded a critical component of sustainable livelihood strategies for the hillsides of Honduras. However, neoliberal polices have reduced economic incentives for agricultural intensification. Recent studies indicate off-farm work opportunities address poverty in a way conservation and development efforts do not. Yet off-farm work may discourage poor farmers from practicing soil conservation. A middle ground is needed. This study indicates micro-credit can substitute for off-farm work and encourage soil conservation practice. Many regions throughout Honduras have had extensive contact with soil conservation programs and would benefit more from credit services than redundant technological extension.

Computation of plasma hemoglobin nitric oxide scavenging in hemolytic anemias

Intravascular hemoglobin limits the amount of endothelial-derived nitric oxide (NO) available for vasodilation. Cell-free hemoglobin scavenges NO more efficiently than red blood cell-encapsulated hemoglobin. Hemolysis has recently been suggested to contribute to endothelial dysfunction based on a mechanism of NO scavenging by cell-free hemoglobin. Although experimental evidence for this phenomenon has been presented, support from a theoretical approach has, until now, been missing. Indeed, due to the low amounts of cell-free hemoglobin present in these pathological conditions, the role of cell-free hemoglobin scavenging of NO in disease has been questioned. In this study, we model the effects of cell-free hemoglobin on NO bioavailability, focusing on conditions that closely mimic those under known pathological conditions. We find that as little as 1 microM cell-free intraluminal hemoglobin (heme concentration) can significantly reduce NO bioavailability. In addition, extravasation of hemoglobin out of the lumen has an even greater effect. We also find that low hematocrit associated with anemia increases NO bioavailability but also leads to increased susceptibility to NO scavenging by cell-free hemoglobin. These results support the paradigm that cell-free hemoglobin released into plasma during intravascular hemolysis in human disease contributes to the experimentally observed reduction in NO bioavailability and endothelial dysfunction.     

Low-dose intravenous nitrite improves hemodynamics in a canine model of acute pulmonary thromboembolism

Acute pulmonary thomboembolism (APT)-induced pulmonary hypertension can be counteracted by activating the nitric oxide (NO)-cGMP pathway. Recent studies have demonstrated that the naturally occurring anion nitrite (NO₂^-) is a bioactive storage reservoir for NO, and is reduced to NO under conditions of hypoxia and acidosis. We hypothesized that nitrite infused intravenously could attenuate the hemodynamic changes associated with APT. APT was induced with autologous blood clots injected into the right atrium in mongrel dogs. After APT (or saline), the dogs received an intravenous nitrite (or saline) infusion (6.75 μmol/kg over 15 min and then 0.28 μmol/kg/min) and hemodynamic evaluations were carried out for 2 h. Plasma nitrite concentrations were measured using ozone-based reductive chemiluminescence methodologies. APT decreased cardiac index (CI) and increased pulmonary vascular resistance index (PVRI); these effects were improved during infusions of sodium nitrite. Accordingly, nitrite infusion increased cardiac index by 28%, reduced the PVRI by 48%, and the systemic vascular resistance index (SVRI) by 21% in embolized dogs, suggesting a greater effect on the ischemic embolized vascular system than the systemic circulation following embolization. Interestingly, in nonembolized control dogs the same nitrite infusion decreased MAP and CI (all P < 0.05). The nitrite infusion increased plasma nitrite concentrations by approximately 2 μM, and produced dose-dependent effects on PVRI, MAP, and SVRI. Remarkably, blood levels of nitrite as low as 500 nM decreased PVRI and SVRI in this model, suggesting a potential role of nitrite in physiological blood flow regulation. These results suggest that a low-dose nitrite infusion produces beneficial hemodynamic effects in a dog model of APT. These findings suggest a new therapeutic application for nitrite and support emerging evidence for a surprisingly potent and potentially physiological vasoactivity of nitrite.     

Molecular phylogeny in endemic weevils: revision of the genera of Macaronesian Cryptorhynchinae (Coleoptera: Curculionidae)

A molecular phylogeny and lineage age estimates are presented for the Macaronesian representatives of the weevil subfamily Cryptorhynchinae, using two mitochondrial genes (cytochrome c oxidase subunit 1 and 16S). The Bayesian reconstruction is supplemented by observations on morphology, ecology, and reproductive biology. The present study often corroborates the groups previously outlined in higher‐level informal taxonomies. These and further groups are now assigned new taxonomic status. The following genera and subgenera are described (formerly Acalles): Aeoniacalles gen. nov. , Canariacalles gen. nov. , Ficusacalles gen. nov. , Madeiracalles gen. nov. , Silvacalles gen. nov. (with Tolpiacalles subgen. nov. , Tagasastacalles subgen. nov. ), Sonchiacalles gen. nov. , Echiumacalles gen. nov. (monotypic), Lauriacalles gen. nov. (monotypic), and Pseudodichromacalles gen. nov. (monotypic; formerly Dichromacalles). For the western Palaearctic genus Acalles Schoenherr, 1825 the first subgenus Origoacalles subgen. nov. is described and for the genus Onyxacalles Stüben, 1999 the first subgenus Araneacalles subgen. nov. ; Paratorneuma Roudier 1956 resyn. Except for one species of Acalles (Origoacalles), all of these new higher taxa are endemic to the Macaronesian Islands. All new taxa are presented, together with their host plants and further data, in a synoptic tabular overview. Based on the results of our phylogenetic analysis, we advocate the hypothesis that the evolution of the species in the new genera (of which most group into a ‘Macaronesian clade’) began in the comparatively arid succulent bush zone and that the shady and humid laurel forest of the thermo‐Canarian and thermo‐Madeiran zone was entered much later. Our reconstruction implies that the Canarian and Madeiran archipelagos were colonized by Cryptorhynchinae at least seven times from the continent but saw only one considerable adaptive radiation. It also becomes apparent that it is the ancestor species of the genus Canariacalles– and not Pseudodichromacalles– that features a close connection to the south‐western European and north‐western African species of Dichromacalles s.s. Finally, a key is presented for all genera and subgenera of the Macaronesian Cryptorhynchinae. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 40–87.     

Pollination strategies in Cretan Arum lilies

Flowers of the genus Arum are known to attract dung‐breeding flies and beetles through olfactory deceit. In addition to this strategy, the genus has evolved several other pollination mechanisms. The present study aimed to characterize the pollination strategies of the Cretan Arum species by investigating the flowering phenology, thermogeny, inflorescence odours, and the pollinating fauna. The results obtained show that Arum cyrenaicum and Arum concinnatum emit a strong dung smell and exhibit the distinctive features associated with this pollination syndrome. Both species are highly thermogenic, have a similar odour profile and attract small‐bodied Diptera. Although sharing the same habitat, these two plant species are never found growing sympatrically as a result of the early blooming period of A. cyrenaicum. By contrast, Arum creticum and Arum idaeum have evolved a more traditional and mutually beneficial pollination mechanism. The stinking smell has been replaced by a more flower‐like odour that attracts bees (Lasioglossum sp.) and, occasionally, bugs (Dionconotus cruentatus). Although attracting the same pollinator, the main compound present in the odour of A. creticum is different from that of A. idaeum. Principal component analysis (PCA), based on physiologically active components of the flower odours determined by testing on the antenna of the Lasioglossum bee, revealed two different clusters, indicating that pollinators can potentially discriminate between the odours of the two species. A further PCA on the main floral odour volatiles as identified by gas chroatography‐mass spectroscopy from all the Arum species under investigation displayed odour‐based similarities and differences among the species. The PCA‐gas chomotography‐electroantennographic detection active peaks analysis showed that the two species, A. creticum and A. idaeum, form two groups and are clearly separated from A. cyrenaicum and A. concinnatum, which, conversely, cluster together. The evolutionary forces and selective pressures leading to diversification of pollination mechanisms in the Cretan Arum spp. are discussed. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 991–1001.     

Imaging hemoglobin oxygen saturation in sickle cell disease patients using noninvasive visible reflectance hyperspectral techniques: effects of nitric oxide

Sickle cell disease is characterized by microvascular occlusion and hemolytic anemia, factors that impair tissue oxygen delivery. We use visible reflectance hyperspectral imaging to quantitate skin tissue hemoglobin oxygen saturation (HbO2) and to determine whether changes in blood flow during nitric oxide (NO) stimulation or gas administration (therapies proposed for this disease) improve skin tissue oxygen saturation in five patients with sickle cell disease. Compared with six healthy African-American subjects, sickle cell patients exhibited higher forearm blood flows (7.4 +/- 1.8 vs. 3.2 +/- 0.4 ml.min-1.100 ml tissue-1, P = 0.037) but significantly reduced percentages of skin HbO2 (61.0 +/- 0.2 vs. 77.5 +/- 0.2%, P < 0.001). Administration of acetylcholine to patients increased blood flow by 15.1 +/- 3.8 ml.min-1.100 ml tissue-1 and the percentage of skin HbO2 by 4.1 +/- 0.3% (P = 0.02, P < 0.001, respectively, from baseline values). Sodium nitroprusside, a direct NO donor, increased blood flow by 3.9 +/- 1.1 ml/min and the percentage of skin HbO2 by 2.9 +/- 0.3% (P = 0.02, P < 0.001, respectively). NO inhalation had no effect on forearm blood flow, yet increased the percentage of skin HbO2 by 2.3 +/- 0.3% (P < 0.001). Percentages of skin HbO2 were exponentially related to blood flow (R = 0.97, P < 0.001), indicating a limit to skin tissue oxygen saturation at high blood flows. Thus, for acetylcholine infusion leading to blood flows sevenfold greater than those of healthy resting African-American subjects, patients still exhibited lower percentages of skin HbO2 (65.2 +/- 0.2 vs. 77.5 +/- 0.2%, P < 0.001). Visible reflectance hyperspectral imaging demonstrates that either the stimulation or the administration of NO pharmacologically or by gas inhalation improves, but does not normalize, skin tissue oxygen saturation in patients with sickle cell disease.