Roles for leakiness and O2 evolution in explaining lower-than-theoretical quantum yields of photosynthesis in the PEP-CK subtype of C4 plants.

Theoretically, the PEP-CK C4 subtype has a higher quantum yield of CO2 assimilation ( Φ CO 2 ) than NADP-ME or NAD-ME subtypes because ATP required for operating the CO2-concentrating mechanism is believed to mostly come from the mitochondrial electron transport chain (mETC). However, reported Φ CO 2 is not higher in PEP-CK than in the other subtypes. We hypothesise, more photorespiration, associated with higher leakiness and O2 evolution in bundle-sheath (BS) cells, cancels out energetic advantages in PEP-CK species. Nine species (two to four species per subtype) were evaluated by gas exchange, chlorophyll fluorescence, and two-photon microscopy to estimate the BS conductance (gbs) and leakiness using a biochemical model. Average gbs estimates were 2.9, 4.8, and 5.0 mmol m-2 s-1 bar-1, and leakiness values were 0.129, 0.179, and 0.180, in NADP-ME, NAD-ME, and PEP-CK species, respectively. The BS CO2 level was somewhat higher, O2 level was marginally lower, and thus, photorespiratory loss was slightly lower, in NADP-ME than in NAD-ME and PEP-CK species. Differences in these parameters existed among species within a subtype, and gbs was co-determined by biochemical decarboxylating sites and anatomical characteristics. Our hypothesis and results partially explain variations in observed Φ CO 2 , but suggest that PEP-CK species probably use less ATP from mETC than classically defined PEP-CK mechanisms.

Awareness of European practitioners toward uncommon tropical diseases: are we prepared to deal with mass migration? Results of an international survey.

PURPOSE: The recent rise in migration from Africa through the Mediterranean basin into Europe has resulted in an increased incidence of uncommon diseases such as schistosomiasis and genito-urinary tuberculosis, which were previously largely unknown in this region. This study aimed to evaluate the insight of European urologists into diagnosing and managing these disease conditions and to determine whether they were adequately prepared to deal with the changing disease spectrum in their countries. METHODS: A survey including specific questions about the diagnosis and management of 'tropical' urological diseases was distributed among urologists working in Europe and Africa. Multivariate logistic regression models were performed to detect the continent (African or European) effect on knowledge of and insight into tropical urological diseases. RESULTS: A total of 312 surveys were administered. African and European respondents accounted for 109 (36.09%) and 193 (63.91%) respondents, respectively. The multivariate logistic regression analysis demonstrated a significant deficiency in the knowledge of tropical urological diseases in the European cohort compared with the African cohort (p < 0.05). Moreover, in the European cohort, markedly superior knowledge of tropical urological diseases was observed for respondents who had previously worked in a developing country. CONCLUSIONS: Though European urologists are not required to have the same insight as African urologists, they showed a very unsatisfactory knowledge of tropical urological diseases. The experience of working in a developing country could improve the knowledge of European urologists regarding tropical urological diseases.