Isohydric species are not necessarily more carbon limited than anisohydric species during drought.

Isohydry (i.e., strong regulation of leaf water potential, Ψl) is commonly associated with strict stomatal regulation of transpiration under drought, which in turn is believed to minimize hydraulic risk at the expense of reduced carbon assimilation. Hence, the iso/anisohydric classification has been widely used to assess drought resistance and mortality mechanisms across species, with isohydric species being hypothetically more prone to carbon starvation and anisohydric species more vulnerable to hydraulic failure. These hypotheses and their underlying assumptions, however, have rarely been tested under controlled, experimental conditions. Our objective is to assess the physiological mechanisms underlying drought resistance differences between two co-occurring Mediterranean forest species with contrasting drought responses: Phillyrea latifolia L. (anisohydric and more resistant to drought) and Quercus ilex L. (isohydric and less drought resistant). A total of 100 large saplings (50 per species) were subjected to repeated drought treatments for a period of 3 years, after which Q. ilex showed 18% mortality whereas no mortality was detected in P. latifolia. Relatively isohydric behavior was confirmed for Q. ilex, but higher vulnerability to cavitation in this species implied that estimated embolism levels were similar across species (12-52% in Q. ilex vs ~30% in P. latifolia). We also found similar seasonal patterns of stomatal conductance and assimilation between species. If anything, the anisohydric P. latifolia tended to show lower assimilation rates than Q. ilex under extreme drought. Similar growth rates and carbon reserves dynamics in both species also suggests that P. latifolia was as carbon-constrained as Q. ilex. Increasing carbon reserves under extreme drought stress in both species, concurrent with Q. ilex mortality, suggests that mortality in our study was not triggered by carbon starvation. Our results warn against making direct connections between Ψl regulation, stomatal behavior and the mechanisms of drought-induced mortality in plants.

[Infective morbidity of replacement therapy in congenital coagulation deficiencies and its effects on demand of coagulation factors]. / La morbilidad infecciosa del tratamiento sustitutivo en los déficit congénitos de coagulación y su repercusión en la demanda de los factores de coagulación.

BACKGROUND: Analysis of the infective morbidity and mortality secondary to replacement hemotherapy in the population with congenital coagulation deficiencies (CCD) and their consequences on the demand for coagulation factors. METHODS: The 46 patients with CCD diagnosed in the autonomous community (AC) of the Balearic Islands (32 with hemophilia A, 6 with hemophilia B, 4 with von Willebrand's disease 2 with factor VII, 1 with factor X, and 1 with factor XII deficiencies) were investigated for infective morbidity and use of blood products from 1982 to 1987. RESULTS: 97% of the patients had some hepatitis marker, 77% had antibodies against human immunodeficiency virus (HIV) and 17% fulfilled the criteria for the acquired immunodeficiency syndrome (AIDS). There were 7 deaths (15%). The morbidity and mortality increased with age and use of blood products. There was a 46% reduction in factor VIII use between 1982 and 1986, from a mean yearly consumption per hemophiliac patient of 33444 international units (IU) to 18080 IU. CONCLUSIONS: The study results show a high prevalence of hepatitis and HIV, an important reduction in the demand of manufactured coagulation factors and a 15% reduction in the population with CCD during the study years.