Characterization of phosphoinositide kinases in normal and sickle anaemia red cells

PtdIns and PtdInsP kinases from normal erythrocyte (AA) membranes and sickle cell anaemia erythrocyte (SS) membranes have been characterized. PtdIns kinase was studied in native membranes under conditions in which PtdInsP kinase and PtdInsP phosphatase do not express any activity. Kinetic analysis of the AA and SS PtdIns kinases indicate similar K_m values for PtdIns and ATP but higher V_max values for SS PtdIns kinase. PtdInsP kinase was partially purified from erythrocyte ghosts by NaCl extraction. The kinetic parameters of PtdInsP kinase determined under these conditions were similar in AA and SS NaCl extracts. These data suggest the presence of some effector of PtdIns kinase in SS cell membranes, resulting in a greater activity of the enzyme. This leads consequently, to increase the PtdInsP pool and to activate PtdInsP kinase, in agreement with our previous observations of a greater [³²P]Pi incorporation in both polyphosphoinositides in SS cells relatively to AA cells.     

Connecting the dots: from nanodomains to physiological functions of REMORINs

REMORINs (REMs) are a plant-specific protein family, proposed regulators of membrane-associated molecular assemblies and well-established markers of plasma membrane nanodomains. REMs play a diverse set of functions in plant interactions with pathogens and symbionts, responses to abiotic stresses, hormone signaling and cell-to-cell communication. In this review, we highlight the established and more putative roles of REMs throughout the literature. We discuss the physiological functions of REMs, the mechanisms underlying their nanodomain-organization and their putative role as regulators of nanodomain-associated molecular assemblies. Furthermore, we discuss how REM phosphorylation may regulate their functional versatility. Overall, through data-mining and comparative analysis of the literature, we suggest how to further study the molecular mechanisms underpinning the functions of REMs.     

Male Gender,Increased Blood Viscosity,Body Mass Index and Triglyceride Levels Are Independently Associated with Systemic Relative Hypertension in Sickle Cell Anemia

Patients with sickle cell anemia (SCA) have usually lower diastolic, systolic and mean blood pressure (BP) than the general population. However, BP values ≥120/70 mmHg considerably increase the risk for acute and chronic complications in SCA. The aim of this study was to identify biological factors associated with relative hypertension in adults with SCA. We compared the hematological, lipid and hemolytic profiles, as well as blood viscosity, between SCA patients with normal BP (<120/70 mmHg, n = 54) and those with relative hypertension (BP≥120/70 mmHg, n = 43). Our results demonstrated that male gender (OR: 3.49; 95%CI 1.20 to 10.16, p<0.05), triglycerides (OR: 9.19; 95% CI 2.29 to 36.95, p<0.01), blood viscosity (OR: 1.35; 95% CI 1.01 to 1.81, p<0.05) and body mass index (OR: 1.37; 95% CI 1.14 to 1.64, p<0.01) were independent risks factors for relative hypertension in SCA. No association was found between the BP status and the positive history of painful vaso-occlusive crisis or acute chest syndrome. An association between triglycerides level and the occurrence of these two major acute complications was detected. Our study suggests that male gender, increased triglycerides level, BMI and blood viscosity could increase the risk for developing relative hypertension in SCA. In addition, our results support a role of moderately elevated triglycerides in the pathophysiology of vaso-occlusive events.     

Hematological and hemorheological Determinants of the Six-Minute Walk Test Performance in Children with Sickle Cell Anemia

The six-minute walk test is a well-established submaximal exercise reflecting the functional status and the clinical severity of sickle cell patients. The aim of the present cross-sectional study was to investigate the biological determinants of the six-minute walk test performance in children with sickle cell anemia. Hematological and hemorheological parameters, pulmonary function and the six-minute walk test performance were determined in 42 children with sickle cell anemia at steady state. The performance during the six-minute walk test was normalized for age, sex and height and expressed as percentage of the predicted six-minute walk distance. We showed that a high level of anemia, a low fetal hemoglobin expression and low red blood cell deformability were independent predictors of a low six-minute walk test performance. This study describes for the first time the impact of blood rheology in the six-minute walk test performance in children with sickle cell anemia.     

Fear and stress reactions in two species of duck and their hybrid

Susceptibility to fear and stress has often been studied in birds using selection experiments. Crosses between different species of the same genus have also been used to study the type of transmission observed for "fixed action patterns." In this experiment we used a cross between two species (male muscovy and female pekin ducks) to study the genetic transmission of various characteristics of fear reactions and adrenal activity. Males of the three genetic types (two parental species and the hybrid) were submitted to tonic immobility and fear of man tests. Blood was collected for corticosterone assay before and after physiological stress or injection of 5 microg/kg of immediate synacthen (ACTH agonist). The muscovy duck showed lower levels of fear reactions than the pekin duck in the majority of behavioral tests (six of eight). Corticosterone levels were also nearly always the lowest in muscovy ducks (five of six). Generally speaking, the muscovy duck appeared to be less fearful and less susceptible to stress than the pekin duck. The mule duck was similar to one parent, midway between the two, or showed heterosis for fear of man at 10 weeks of age (more fearful than the two parents). Corticosterone levels were midway between the two parents in the mule duck with only one exception, i.e., where the pekin duck was dominant. The existence of heterosis for fear is surprising, as this character is classically considered to be submitted to stabilizing selection. The transmission of corticosterone levels and other fear characteristics is, however, compatible with stabilizing selection. The results are discussed in terms of adaptability.     

Molecular phylogeny of French Guiana Hylinae: implications for the systematic and biodiversity of the Neotropical frogs

In this study we used nucleotide sequences from a segment of mitochondrial 16S ribosomal DNA gene to investigate the evolutionary relationships of some French Guiana Hylinae. New sequences, representing the members of different French Guiana frogs-five specimens of the Scinax genus, two Hyla, one Osteocephalus, one Hyalinobatrachium and two Rana as out-group-were examined. In addition, 26 sequences available from GenBank database representing the other subfamilies of the Hylidae were added to our study. This work allowed us to clarify relationships within the four hylids subfamilies (Pelodryadinae, Phyllomedusinae, Hemiphractinae and Hylinae) and the phylogenetic placement of the enigmatic Scinax genus within the Hylidae. We found that: (1) the Scinax genus displays a high level of differentiation in comparison to two other genera (Litoria and Hyla) belonging to 'Hylidae' family; (2) the Hylinae are paraphyletic given the position of the Litoria, which was the sister-group of the Hyla and the Osteocephalus genera; (3) the anterior works and our results (based on two different data sets) showed the paraphyly of the Hylidae questioning the validity of this family; (4) the reassessment of these different taxonomic groups will induce a huge implication on the estimation (past, present and future) of the biodiversity (in Neotropical frogs).     

Selective enzymic esterification of free fatty acids with n-butanol under microwave irradiation and under classical heating

Selective enzymic esterification of free fatty acids, obtained from blackcurrant oil by chemical saponification, with n-butanol using four immobilized lipases under microwave irradiation and under classical heating was studied. A positive effect of microwave irradiation on chemical yields of the products of the enzymic reactions and specificity of lipases were observed in comparison with a controlled heating in an incubator equipped with shaking (classical heating) applied during the identical enzyme-mediated processes. The maximum quantity of -linolenic acid (30%) was obtained with Lipozyme used as biocatalyst of the reaction under microwave irradiation. The maximum quantity of butyl -linolenate (20%) was obtained by a Pseudomonas cepacia lipase catalyzed esterification under classical heating.