Amino acid content and nectar choice by forager honeybees (Apis mellifera L.)

Dual choice feeding tests were performed to determine a preference of forager honeybees for specific amino acids. Artificial nectar containing proline was preferred over those containing only sugars. Nectar containing alanine was preferred on the first day, but preference was no longer significant thereafter. On the contrary, a negative response was found for serine. When the bees were given the choice between two nectars enriched with different compounds, proline was preferred above both alanine and serine, and alanine above serine

The long-term impact of Italian colonial roads in the Horn of Africa, 1935-2000

Between 1935 and 1940 the Italians built an extensive road network to facilitate the occupation of Ethiopia and secure control over the Horn of Africa, but were expelled in 1941. This provides a unique case study to examine the long-run effect of cheap transport networks on the concentration of economic activity in developing countries. The results show that cells located next to Italian paved roads are significantly richer today and that the relationship is causal. Persistence is explained by a combination of direct and indirect mechanisms: colonial roads attracted economic activity through lower transport costs until 1960. After that date, the advantage of treated locations persisted only indirectly through increasing returns to scale

Stress-driven increase in proline levels, and not proline levels themselves, correlates with the ability to withstand excess salt in a group of 17 Italian rice genotypes

In most plant species, a rapid increase in free proline content occurs following exposure to hyperosmotic stress conditions. However, inconsistent results were reported concerning the role of such an increase on the plant response to water shortage or excess salt. Therefore, the possibility that proline accumulation may help the cell to withstand stress conditions, or that it simply represents a stress marker, is still a matter of debate. A possible relationship between proline accumulation and salt tolerance was investigated in a set of 17 Italian rice varieties. Rice seedlings were exposed to increasing salt concentrations during germination and early growth. The resulting levels of free proline were measured separately in shoots and roots and compared to those in untreated controls. Results were related to the corresponding ability of a given genotype to tolerate stress conditions. Neither absolute proline levels in untreated or in salt-stressed seedlings showed a straightforward relationship to the relative tolerance to salt, estimated as conductivity values able to reduce growth by 10 or 50%. Conversely, a highly significant correlation was found between the increase in proline levels in shoots and the ability to withstand stress. The results strengthen a recent hypothesis suggesting than an increase in proline metabolic rates, more than the resulting proline content, may help the cell to counteract the effects of abiotic stress conditions

The effect of settler farming on indigenous agriculture: Evidence from Italian Libya

What effect did the settlement of European farmers have on the indigenous agricultural sector during the colonial period? On the one hand, European immigrants imported skills and capital but, on the other, they took control of local resources. By looking at the short-term effect of Italian farming in colonial Libya, I shed new light on this question. Through regression analysis on a novel village dataset covering the entire country, I show that, in 1939, proximity to Italian farms was associated with significantly lower land productivity relative to distant locations. Lower yields can be explained by the adoption of land-extensive cultivation techniques, implemented by indigenous farmers to counteract a labour drain operated by Italian farms through factor markets. The combined mitigating effect of monetary wages and land-extensive farming only partially compensated for the fall in income linked to reduced land productivity

The long-term impact of Italian colonial roads in the Horn of Africa, 1935-2015

This article exploits the quasi-natural experiment provided by the extensive road network that was built across the Horn of Africa during the Italian occupation of Ethiopia (1936–1941), to examine how a first-mover advantage in transportation can affect the spatial distribution of economic activity in developing countries over the long run. The results show that Italian paved roads rendered areas located within 10 km of them significantly more populated, urbanized and luminous around 2010, relative to comparable, more distant locations. Early roadbuilding lifted first-mover locations out of isolation and allowed for net welfare gains, thanks to a reduction in transport costs and specialization. To this day, first-mover locations continue to diverge from the control group, due to a coordination mechanism that led to an oversupply of governmental facilities in the post-colonial period

The long-term impact of the Italian colonial expenditures in the Horn of Africa

A growing body of literature analyses the relationship between colonialism and long-term development, but largely overlooks the effect of colonial public investments on transportation infrastructure, schooling and sanitary facilities. In my research, I exploit the case study of Italian colonial investments in the Horn of Africa between 1934 and 1941, to unveil the relationship between such investments and present-day inequalities in terms of level of development and living standards and to explore the mechanisms that explain the persistence of colonial investments over time. I create three geo-referenced (a grid dataset and two individual) datasets by matching historical data on colonial investments, collected from both archival and printed primary sources, with micro-level open-source contemporary data for development and modern surveys for living standards to perform OLS and probit regression analysis. Firstly, I regress proxies for level of development, such as population density and light density at night, on dummies for being within 20km from colonial roads. Secondly, I regress measures of living standards, such as female literacy, BMI and children holding a sanitary card, on binary variables for living less than 10km away from a colonial schools and hospitals. Several robustness checks are performed to address the possible endogenous placement of colonial facilities including IV estimation, placebo treatment and nearest neighbour score matching. The data show a strong, positive and statistically significant relationship between proximity to colonial roads and economic development, on the one hand, and proximity to schooling, sanitary facilities and living standards, on the other. This demonstrates that areas endowed with more generous investments from the colonial period perform better in terms of economic development and living standards at present. The analysis also points out that the effect persisted mainly through phenomena of path-dependency and re-location.</p

Differential accumulation of γ–aminobutyric acid in elicited cells of two rice cultivars showing contrasting sensitivity to the blast pathogen.

Intracellular free amino acid pools were quantified in suspension cultured cells of a blast-sensitive and a blast-resistant rice genotype at increasing time after the treatment with Magnaporthe oryzae cell wall hydrolysates. Besides some expected variations in free phenylalanine, a remarkable early increase of γ–aminobutyric acid (GABA) levels was evident in both cultivars. Glutamate decarboxylase activity and protein levels were unaffected. GABA homeostasis was recovered in the sensitive cultivar 48 h after the treatment. On the contrary, a further GABA accumulation and a general increase of most amino acids were found at this later stage in the resistant genotype, which showed a higher decrease of cell viability as a consequence of elicitor addition. Data support a recently-hypothesized role of GABA metabolism in the plant response to fungal pathogens

A differential tolerance to mild salt stress conditions among six Italian rice genotypes does not rely on Na+ exclusion from shoots

Rice is very sensitive to salt stress at the seedling level, with consequent poor crop establishment. A natural variability in susceptibility to moderate saline environments was found in a group of six Italian temperate japonica rice cultivars, and the physiological determinants for salt tolerance were investigated. Cation (Na+, K+ and Mg++) levels were determined in shoots from individual rice plantlets grown in the absence or in the presence of inhibitory, yet sublethal salt levels, and at increasing time after salt treatments. Significant variations were found among genotypes, but these were unrelated to the relative tolerance, which seems to result from neither mechanism(s) for reduced Na+ translocation to the aerial part, nor its increased retrieval from the xylem mediating Na+ exclusion from leaves. Accordingly, thiobarbituric acid reactive substance levels raised in leaf tissues of salt-treated seedlings, and osmo-induced proline accumulation was found in all genotypes. Data suggest that the difference in salt tolerance most likely depends on mechanisms for osmotic adjustment and/or antioxidative defence

Amino acid content and nectar preference in forager honeybees

Dual choice feeding tests were performed to verify a preference of forager honeybees for artificial nectars supplemented with various amino acids. Proline-containing nectar was preferred over a solution containing only sugars. Daily individual consumption was initially higher also for alanine-containing nectar, but the difference became not statistically significant afterwards. On the contrary, a negative response was found for serine. When the test was carried out with two nectars enriched with different amino acids, the same preference hierarchy was evident