Crop row spacing and its influence on the partitioning of evapotranspiration by winter-grown wheat in Northern Syria

A study was conducted during the 1996–97 crop growth season at ICARDA in northern Syria, to investigate the influence of wheat canopy architecture on the partitioning of moisture between soil evaporation and crop transpiration, on a soil with high hydraulic conductivity. The study was conducted on the long-term two course wheat-lentil rotation trial, established on a swelling clay soil (Calcixerollic xerochrept). The wheat canopy architecture was manipulated by sowing the crop at either of two row-spacings, 0.17 or 0.30 m, both at a constant sowing rate equivalent to 120 kg ha^–1. In this study, evapotranspiration from the crop was inferred from changes in soil moisture content over time, evaporation and rainfall interception were measured daily using microlysimetry, drainage was estimated as being the difference between potential daily evapotranspiration, and the evapotranspiration estimated from the soil water deficit. Between sowing and day 80 (tillering stage), evapotranspiration was calculated to consist mainly of soil evaporation. However, after day 80, transpiration became an increasingly dominant component of evapotranspiration. For both row-spacings, cumulative evapotranspiration over the season was approximately 373 mm. In the narrow-row crop, transpiration and soil evaporation were approximately 185 mm and 183 mm of water respectively. Conversely for the wide row-spaced crop, 172 mm of water was transpired while about 205 mm of water evaporated from the soil surface. While green leaf area index did not differ between row-spacings, the architecture of the crops as a result of sowing affected solar radiation penetration such that more incident radiation was intercepted at the soil surface of the wide row-spaced crop. This is likely to have made some contribution to the elevated levels of evaporation from the soil beneath the canopy of the wide-sown crop.     

EAACI position paper on occupational rhinitis

The present document is the result of a consensus reached by a panel of experts from European and non-European countries on Occupational Rhinitis (OR), a disease of emerging relevance which has received little attention in comparison to occupational asthma. The document covers the main items of OR including epidemiology, diagnosis, management, socio-economic impact, preventive strategies and medicolegal issues. An operational definition and classification of OR tailored on that of occupational asthma, as well as a diagnostic algorithm based on steps allowing for different levels of diagnostic evidence are proposed. The needs for future research are pointed out. Key messages are issued for each item.     

The Background of Mitochondrial DNA Haplogroup J Increases the Sensitivity of Leber's Hereditary Optic Neuropathy Cells to 2,5-Hexanedione Toxicity

Leber''s hereditary optic neuropathy (LHON) is a maternally inherited blinding disease due to mitochondrial DNA (mtDNA) point mutations in complex I subunit genes, whose incomplete penetrance has been attributed to both genetic and environmental factors. Indeed, the mtDNA background defined as haplogroup J is known to increase the penetrance of the 11778/ND4 and 14484/ND6 mutations. Recently it was also documented that the professional exposure to n-hexane might act as an exogenous trigger for LHON. Therefore, we here investigate the effect of the n-hexane neurotoxic metabolite 2,5-hexanedione (2,5-HD) on cell viability and mitochondrial function of different cell models (cybrids and fibroblasts) carrying the LHON mutations on different mtDNA haplogroups. The viability of control and LHON cybrids and fibroblasts, whose mtDNAs were completely sequenced, was assessed using the MTT assay. Mitochondrial ATP synthesis rate driven by complex I substrates was determined with the luciferine/luciferase method. Incubation with 2,5-HD caused the maximal loss of viability in control and LHON cells. The toxic effect of this compound was similar in control cells irrespective of the mtDNA background. On the contrary, sensitivity to 2,5-HD induced cell death was greatly increased in LHON cells carrying the 11778/ND4 or the 14484/ND6 mutation on haplogroup J, whereas the 11778/ND4 mutation in association with haplogroups U and H significantly improved cell survival. The 11778/ND4 mutation on haplogroup U was also more resistant to inhibition of complex I dependent ATP synthesis by 2,5-HD. In conclusion, this study shows that mtDNA haplogroups modulate the response of LHON cells to 2,5-HD. In particular, haplogroup J makes cells more sensitive to its toxic effect. This is the first evidence that an mtDNA background plays a role by interacting with an environmental factor and that 2,5-HD may be a risk element for visual loss in LHON. This proof of principle has broad implications for other neurodegenerative disorders such as Parkinson''s disease.     

Mapping of HLA epitopes recognized by H-2-restricted cytotoxic T lymphocytes specific for HLA using recombinant genes and synthetic peptides

Immunization of DBA/2 (H-2d) mice with syngeneic P815 tumor cell transfectants that express HLA class I genes elicits CTL that recognize HLA in the context of H-2Kd molecules. Anti-HLA-CW3 CTL cross-react to a variable extent on the related alleles A3 and A24. Using a panel of target cells expressing native or recombinant HLA genes, we could map the epitope recognized by a CTL clone specific for CW3 to the second external (alpha 2) domain of CW3. Moreover, the epitope recognized by this clone could be mimicked by incubating P815 (HLA negative) target cells with a synthetic peptide corresponding to the C-terminal 12 amino acids of the CW3 alpha 2 domain (residues 171 to 182). Other independent anti-CW3 CTL clones with different fine specificities recognized the same CW3 peptide. In contrast, CTL clones specific for HLA-A24 or HLA-A3 that did not lyse P815-CW3 transfectants did not recognize this peptide. The CW3 peptide could be recognized on other tumor cell targets that were also of H-2d origin, but not on those of H-2b or H-2k origin. The requirement for the expression of H-2Kd by the target cells was directly demonstrated using L cell Kd transfectants. Our results suggest that the CTL response of DBA/2 mice immunized with P815-CW3 transfectants is predominantly Kd restricted and focused on epitopes contained within the 12 C-terminal amino acids of the alpha 2 domain.     

Competition between unrelated peptides recognized by H-2-Kd restricted T cells

P815 (H-2d) target cells incubated with synthetic peptides corresponding to region 170-182 of HLA or to region 141-161 of influenza nucleoprotein (NP) are lysed by DBA/2 derived cytolytic T cells (CTL) specific for HLA or by BALB/c derived CTL-specific for NP, respectively. Both peptide Ag are recognized in the context of Kd. We show herein that these unrelated, nonhomologous peptides clearly compete reciprocally for recognition by the appropriate Kd restricted CTL. In contrast, different NP peptides that are recognized by other CTL restricted by HLA-B37, H-2-Db or KK, either failed to compete or were much less efficient as competitors than NP peptides recognized in the context of Kd. The efficiency of a peptide as a competitor correlated with its potency as an Ag. The most efficient competitor was a variant peptide of NP 147-158 with R156 deleted, which had been previously shown to be 1,000 times more efficient as an Ag than its natural homolog. Our results suggest that peptides recognized by CTL in the context of the same MHC class I restriction element may bind to the same or interdependent site(s) on the restriction molecule.