Optimization of multi-environment trials for genomic selection based on crop models.

KEY MESSAGE: We propose a statistical criterion to optimize multi-environment trials to predict genotype × environment interactions more efficiently, by combining crop growth models and genomic selection models. Genotype × environment interactions (GEI) are common in plant multi-environment trials (METs). In this context, models developed for genomic selection (GS) that refers to the use of genome-wide information for predicting breeding values of selection candidates need to be adapted. One promising way to increase prediction accuracy in various environments is to combine ecophysiological and genetic modelling thanks to crop growth models (CGM) incorporating genetic parameters. The efficiency of this approach relies on the quality of the parameter estimates, which depends on the environments composing this MET used for calibration. The objective of this study was to determine a method to optimize the set of environments composing the MET for estimating genetic parameters in this context. A criterion called OptiMET was defined to this aim, and was evaluated on simulated and real data, with the example of wheat phenology. The MET defined with OptiMET allowed estimating the genetic parameters with lower error, leading to higher QTL detection power and higher prediction accuracies. MET defined with OptiMET was on average more efficient than random MET composed of twice as many environments, in terms of quality of the parameter estimates. OptiMET is thus a valuable tool to determine optimal experimental conditions to best exploit MET and the phenotyping tools that are currently developed.

Honeybee locomotion is impaired by Am-CaV3 low voltage-activated Ca2+ channel antagonist.

Voltage-gated Ca2+ channels are key transducers of cellular excitability and participate in several crucial physiological responses. In vertebrates, 10 Ca2+ channel genes, grouped in 3 families (CaV1, CaV2 and CaV3), have been described and characterized. Insects possess only one member of each family. These genes have been isolated in a limited number of species and very few have been characterized although, in addition to their crucial role, they may represent a collateral target for neurotoxic insecticides. We have isolated the 3 genes coding for the 3 Ca2+ channels expressed in Apis mellifera. This work provides the first detailed characterization of the honeybee T-type CaV3 Ca2+ channel and demonstrates the low toxicity of inhibiting this channel. Comparing Ca2+ currents recorded in bee neurons and myocytes with Ca2+ currents recorded in Xenopus oocytes expressing the honeybee CaV3 gene suggests native expression in bee muscle cells only. High-voltage activated Ca2+ channels could be recorded in the somata of different cultured bee neurons. These functional data were confirmed by in situ hybridization, immunolocalization and in vivo analysis of the effects of a CaV3 inhibitor. The biophysical and pharmacological characterization and the tissue distribution of CaV3 suggest a role in honeybee muscle function.

Bread wheat milling behavior: effects of genetic and environmental factors, and modeling using grain mechanical resistance traits.

KEY MESSAGE: Genetic (Pinb-D1 alleles) and environment (through vitreousness) have important effects on bread wheat milling behavior. SKCS optimal values corresponding to soft vitreous or hard mealy grains were defined to obtain the highest total flour yield. Near-isogenic lines of bread wheat that differ in hardness, due to distinct puroindoline-b alleles (the wild type, Pinb-D1a, or the mutated forms, Pinb-D1b or Pinb-D1d), were grown in different environments and under two nitrogen fertilization levels, to study genetic and environmental effects on milling behavior. Milling tests used a prototype mill, equipped with two break steps, one sizing step, and two reduction steps, and this enabled 21 individual or aggregated milling fractions to be collected. Four current grain characters, thousand grain weight, test weight, grain diameter, and protein content, were measured, and three characters known to influence grain mechanical resistance, NIRS hardness, SKCS hardness index, and grain vitreousness (a character affecting the grain mechanical behavior but generally not studied). As expected, the wild type or mutated forms of Pinb-D1 alleles led to contrasted milling behavior: soft genotypes produced high quantities of break flour and low quantities of reduction flour, whereas reverse quantities were observed for hard genotypes. This different milling behavior had only a moderate influence on total flour production. NIRS hardness and vitreousness were, respectively, the most important and the second most important grain characters to explain milling behavior. However, contrary to NIRS hardness, vitreousness was only involved in endosperm reduction and not in the separation between the starchy endosperm and the outer layers. The highest flour yields were obtained for SKCS values comprised between 30 and 50, which corresponded either to soft vitreous or hard mealy grains. Prediction equations were defined and showed a good accuracy estimating break and reduction flours portions, but should be used more cautiously for total flour.

Pathological fractures in children: Diagnosis and treatment options.

A fracture is defined as pathological when it arises in a bone tissue that has been modified and reshaped by a local or systemic pathological process. In children, pathological fractures can be secondary to several conditions, ranging from metabolic diseases to tumors, infections or neuromuscular pathologies. History, clinical examination and radiologic assessment are essential to making a diagnosis, to identifying the underlying cause and to planning the right treatment of a pathological fracture. Treatment must be tailored to both the fracture and the underlying cause. The objective of this work is to present the diagnostic approach and the course to follow when a child presents with a pathological fracture. The most common causes of pathological fractures, as well as their characteristics, will be described. Pathological fractures occurring in osteogenesis imperfecta and in abused children as well as stress fractures will not be discussed.

PDGFRß(+) cells in human and experimental neuro-vascular dysplasia and seizures.

INTRODUCTION: Neuro-vascular rearrangement occurs in brain disorders, including epilepsy. Platelet-derived growth factor receptor beta (PDGFRß) is used as a marker of perivascular pericytes. Whether PDGFRß(+) cell reorganization occurs in regions of neuro-vascular dysplasia associated with seizures is unknown. METHODS: We used brain specimens derived from epileptic subjects affected by intractable seizures associated with focal cortical dysplasia (FCD) or temporal lobe epilepsy with hippocampal sclerosis (TLE-HS). Tissues from cryptogenic epilepsy, non-sclerotic hippocampi or peritumoral were used for comparison. An in vivo rat model of neuro-vascular dysplasia was obtained by pre-natal exposure to methyl-axozy methanoic acid (MAM). Status epilepticus (SE) was induced in adult MAM rats by intraperitoneal pilocarpine. MAM tissues were also used to establish organotypic hippocampal cultures (OHC) to further assess pericytes positioning at the dysplastic microvasculature. PDGFRß and its colocalization with RECA-1 or CD34 were used to segregate perivascular pericytes. PDGFRß and NG2 or IBA1 colocalization were performed. Rat cortices and hippocampi were used for PDGFRß western blot analysis. RESULTS: Human FCD displayed the highest perivascular PDGFRß immunoreactivity, indicating pericytes, and presence of ramified PDGFRß(+) cells in the parenchyma and proximal to microvessels. Tissues deriving from human cryptogenic epilepsy displayed a similar pattern of immunoreactivity, although to a lesser extent compared to FCD. In TLE-HS, CD34 vascular proliferation was paralleled by increased perivascular PDGFRß(+) pericytes, as compared to non-HS. Parenchymal PDGFRß immunoreactivity co-localized with NG2 but was distinct from IBA1(+) microglia. In MAM rats, we found pericyte-vascular changes in regions characterized by neuronal heterotopias. PDGFRß immunoreactivity was differentially distributed in the heterotopic and adjacent normal CA1 region. The use of MAM OHC revealed microvascular-pericyte dysplasia at the capillary tree lining the dentate gyrus (DG) molecular layer as compared to control OHC. Severe SE induced PDGFRß(+) immunoreactivity mostly in the CA1 region of MAM rats. CONCLUSION: Our descriptive study points to microvascular-pericyte changes in the epileptic pathology. The possible link between PDGFRß(+) cells, neuro-vascular dysplasia and remodeling during seizures is discussed.

Relationships between wheat grain physical characteristics studied through near-isogenic lines with distinct puroindoline-b allele.

KEY MESSAGE: Genetic (different forms of puroindoline-b) and environment (through variations in vitreousness), have important effects on wheat grain mechanical properties. The two methods of hardness measurements (NIRS, SKCS) do not give the same information. Bread wheat near-isogenic lines differing in hardness, due to distinct puroindoline-b alleles (the wild type, Pinb-D1a, or the mutated forms, Pinb-D1b or Pinb-D1d), were grown for three years in seven sites and under two nitrogen fertilization levels, to study genetic and environmental effects on grain mechanical properties. Two methods, Near-Infrared Reflectance Spectroscopy (NIRS) and Single Kernel Characterization System (SKCS), currently used for grain hardness characterization, were carried out. Grain vitreousness, which is known to affect the grain mechanical behavior but is generally not studied, was also measured, as well as three other characters (Thousand Grain Weight, Test Weight and protein content). The relationships between the different characters were studied. Results revealed a clear effect of the different Pinb-D1 alleles on NIRS hardness, and a marked impact of the environmental conditions on vitreousness. SKCS hardness was influenced by both Pinb-D1 alleles and environmental conditions. The relationship between SKCS and NIRS hardness was strong when considering together soft and hard genotypes, but moderate within a class of genetical hardness. Vitreousness had only a weak effect on NIRS hardness, whereas vitreousness and SKCS values were strongly correlated, with two distinct regressions for soft and hard genotypes. Vitreousness was positively related to protein content, especially in the case of hard genotypes, which were able to reach high vitreousness values never observed for soft genotypes.

A comparison of the simplified olecranon and digital methods of assessment of skeletal maturity during the pubertal growth spurt.

Assessment of skeletal age is important in children's orthopaedics. We compared two simplified methods used in the assessment of skeletal age. Both methods have been described previously with one based on the appearance of the epiphysis at the olecranon and the other on the digital epiphyses. We also investigated the influence of assessor experience on applying these two methods. Our investigation was based on the anteroposterior left hand and lateral elbow radiographs of 44 boys (mean: 14.4; 12.4 to 16.1 ) and 78 girls (mean: 13.0; 11.1 to14.9) obtained during the pubertal growth spurt. A total of nine observers examined the radiographs with the observers assigned to three groups based on their experience (experienced, intermediate and novice). These raters were required to determined skeletal ages twice at six-week intervals. The correlation between the two methods was determined per assessment and per observer groups. Interclass correlation coefficients (ICC) evaluated the reproducibility of the two methods. The overall correlation between the two methods was r = 0.83 for boys and r = 0.84 for girls. The correlation was equal between first and second assessment, and between the observer groups (r ≥ 0.82). There was an equally strong ICC for the assessment effect (ICC ≤ 0.4%) and observer effect (ICC ≤ 3%) for each method. There was no significant (p < 0.05) difference between the levels of experience. The two methods are equally reliable in assessing skeletal maturity. The olecranon method offers detailed information during the pubertal growth spurt, while the digital method is as accurate but less detailed, making it more useful after the pubertal growth spurt once the olecranon has ossified.

Effect of status epilepticus and antiepileptic drugs on CYP2E1 brain expression.

P450 metabolic enzymes are expressed in the human and rodent brain. Recent data support their involvement in the pathophysiology of epilepsy. However, the determinants of metabolic enzyme expression in the epileptic brain are unclear. We tested the hypothesis that status epilepticus (SE) or exposure to phenytoin or phenobarbital affects brain expression of the metabolic enzyme CYP2E1. SE was induced in C57BL/6J mice by systemic kainic acid. Brain CYP2E1 expression was evaluated 18-24h after severe SE by immunohistochemistry. Co-localization with neuronal nuclei (NEUN), glial fibrillary acidic protein (GFAP) and CD31 was determined by confocal microscopy. The effect of phenytoin, carbamazepine and phenobarbital on CYP2E1 expression was evaluated in vivo or by using organotypic hippocampal cultures in vitro. CYP2E1 expression was investigated in brain resections from a cohort of drug-resistant epileptic brain resections and human endothelial cultures (EPI-EC). Immunohistochemistry showed an increase of CYP2E1 expression limited to hippocampal CA2/3 and hilar neurons after severe SE in mice. CYP2E1 expression was also observed at the astrocyte-vascular interface. Analysis of human brain specimens revealed CYP2E1 expression in neurons and vascular endothelial cells (EC). CYP2E1 was expressed in cultured human EC and over-expressed by EPI-EC. When analyzing the effect of drug exposure on CYP2E1 expression we found that, in vivo or in vitro, ethanol increased CYP2E1 levels in the brain and liver. Treatment with phenytoin induced localized CYP2E1 expression in the brain whereas no significant effects were exerted by carbamazepine or phenobarbital. Our data indicate that the effect of acute SE on brain CYP2E1 expression is localized and cell specific. Exposure to selected anti-epileptic drugs could play a role in determining CYP2E1 brain expression. Additional investigation is required to fully reproduce the culprits of P450 enzyme expression as observed in the human epileptic brain.

Functional results of displaced proximal humerus fractures in children treated by elastic stable intramedullary nail.

PURPOSE: Displaced proximal humerus fractures within the pediatric population can be treated by elastic stable intramedullary nailing (ESIN). The main objective of our study is to evaluate functional outcome of the displaced proximal humeral fractures treated by ESIN within the pediatric group using a standardized evaluation scale. The secondary goal is to compare functional outcome of epiphyseal and metaphyseal injuries and functional outcome of children younger and older than 10 years of age. MATERIALS AND METHODS: From March 2010 to December 2011, 27 children had been treated surgically using ESIN for displaced fractures at the proximal extremity of the humerus. These fractures were displaced and closed without neurovascular insult. Patients were followed radiographically and clinically on a regular basis. After hardware removal, the functional outcomes had been homogeneously assessed by using the French edition of the QuickDash(®) evaluation scale. The descriptive statistics including mean, standard deviation, and confidence interval have been realized. RESULTS: We included 27 children who were operated on consecutively (10 boys, 17 girls). The mean age at the time of operation is 11.2 ± 2.7 years (range 7.1-15.9). The mean angulation is 55.9° ± 20.3° (range 20-90). The mean apposition is 52.8 % ± 33.1 (range 10-100). The mean follow-up period is 15.2 ± 5.6 months (range 6.1-28.5). Results were considered good for children between 7.1 and 15.9 years old with epiphyseal and meataphyseal fractures. The mean QuickDash(®) score is 2.0 (range 0-6.5), with 14 cases showing a score of 0 (58.3 %), 2 cases with 4.3 (8.3 %), 4 cases with 4.5 (16.7 %), and 4 cases with a score of 6.5 (16.7 %). Ranges of movement were preserved. The patients regained their daily and sportive activity over the time without pain or discomfort. CONCLUSION: Our study showed a good outcome of functional results within a pediatric population who had a sustained displaced proximal humeral fracture and treated by ESIN. Using a standardized evaluation scale is recommended in order to be able to evaluate the patients in a homogeneous manner.

[Giant ameloblastoma of the mandible]. / Améloblastome géant mandibulaire.

INTRODUCTION: Giant ameloblastomas are more common in developing countries. They raise a serious problem of management. We present the case of one of the largest ameloblastoma ever reported. CASE REPORT: A 48-year-old Congolese female patient was referred for mandibular swelling having begun 23 years before and now inducing severe functional disorders. A cephalic CT scan revealed a multicystic mass, 30×18×10cm in size, with a typical "soap bubble" presentation, and with thinned and inflated cortical bone. The treatment was sub-total segmental mandibulectomy with immediate reconstruction using a fibular free flap, modeled on the sampling site by four ostectomies. The pathological examination confirmed the diagnosis of a benign follicular and plexiform ameloblastoma. The excess of soft tissue was treated with a right commissuroplasty on the 15th postoperative day. There was no complication. DISCUSSION: Radical treatment followed by immediate reconstruction using a free flap is the treatment of choice for giant mandibular ameloblastomas, when considering immediate functional and esthetic benefits. This is a prime concern for patients with a difficult access to health care and for whom long-term follow-up is not feasible.

15-year follow-up of a case of amelogenesis imperfecta: importance of psychological aspect and impact on quality of life.

BACKGROUND: Amelogenesis imperfecta (AI) represents a group of hereditary conditions which affects enamel formation in the primary and permanent dentitions. Gene mutations alter the quality and/or quantity of enamel. AI often has severe consequences for the patient such as high tooth sensitivity, low aesthetic quality of the dentition, and poor mechanical properties of the dental tissues. This can result in reduced oral health-related quality of life. CASE REPORT: We present the case of a child affected by AI which had been diagnosed at the age of 9 years. Teeth presented many enamel defects. The patient presented thin brown to yellow enamel and the surface was rough and granular. He revealed short clinical crowns, occlusal wear with exposed dentine in posterior areas. He also presented a lateral open bite and lingual lateral interposition due to partial destruction of deciduous molars. Panoramic radiograph showed no differences between enamel and dentine appearance and also coronary destruction of permanent molars. TREATMENT: The initial treatment consisted of adaptation of composite resins on permanent incisors to improve aesthetics. Preformed metal crowns were placed on first permanent molars to prevent their premature destruction. FOLLOW-UP: This was disrupted for a variety of reasons. Fourteen years later, after a dental nomadism, the patient consulted by chance a dentist who identified his genetic pathology and was aware of its consequences. Extensive prosthodontic treatment was needed, but oral hygiene was poor and gingivitis remained. CONCLUSION: Dealing with high loss of motivation has been one of the main challenges because this patient had a lot of psychological problems. He was concerned, as are many patients affected by AI or other enamel abnormalities. This paper highlights the difficulties of long-term care of this dental abnormality. Psychological aspects of the quality of life, which is a common feature in patients suffering from many kinds of enamel anomalies, are very important.

Validation of quantitative polymerase chain reaction methodology for monitoring DNA as a surrogate marker for species material contamination in porcine heparin.

Heparin is a widely used intravenous anticoagulant comprising of a very complex mixture of glycosaminoglycan chains, mainly derived from porcine intestinal mucosa. The species of origin and the absence of contaminants from other species are important determinants of the different physicochemical characteristics of heparin. They also determine the potential for introducing infectious and adventitious agents into heparin batches destined for medicinal use. We perform routine quantitative polymerase chain reaction (Q-PCR) release tests to confirm the quality of all crude heparin batches, including those used for the manufacture of enoxaparin sodium. Here we further demonstrate that the assessment of the DNA content in crude heparin is a good surrogate marker of contamination at the mucosa level. After spiking porcine mucosa with ovine mucosa and processing this material to form crude heparin, we were able to observe similar ratios of species-specific DNA in both the starting and end products. Experiments performed with 3,000 and 1,500 ppm contamination found these concentrations to be well above the detection limit for our assay of heparin batches. Additionally this Q-PCR method can be used to detect contamination in mucosa, thus providing a tool capable of monitoring for contaminants throughout the crude heparin manufacturing process. Q-PCR analysis of industrial crude heparin samples has confirmed over time the value of this method to assess the pure porcine origin of heparin.

Genome-wide association analysis to identify chromosomal regions determining components of earliness in wheat.

The modification of flowering date is considered an important way to escape the current or future climatic constraints that affect wheat crops. A better understanding of its genetic bases would enable a more efficient and rapid modification through breeding. The objective of this study was to identify chromosomal regions associated with earliness in wheat. A 227-wheat core collection chosen to be highly contrasted for earliness was characterized for heading date. Experiments were conducted in controlled conditions and in the field for 3 years to break down earliness in the component traits: photoperiod sensitivity, vernalization requirement and narrow-sense earliness. Whole-genome association mapping was carried out using 760 molecular markers and taking into account the five ancestral group structure. We identified 62 markers individually associated to earliness components corresponding to 33 chromosomal regions. In addition, we identified 15 other significant markers and seven more regions by testing marker pair interactions. Co-localizations were observed with the Ppd-1, Vrn-1 and Rht-1 candidate genes. Using an independent set of lines to validate the model built for heading date, we were able to explain 34% of the variation using the structure and the significant markers. Results were compared with already published data using bi-parental populations giving an insight into the genetic architecture of flowering time in wheat.

[Consumption of fruit juices and fruit drinks: impact on the health of children and teenagers, the dentist's point of view]. / Impact des jus de fruits et des boissons fruitées sur la santé de l'enfant et de l'adolescent: le point de vue du chirurgien dentiste.

OBJECTIVES: The French dietary guidelines published in 2001 recommend daily consumption of 5 portions of fruit or vegetable. Despite this advice, the consumption of fruit in France, especially in the north of France, is low, whereas sale of 100% fruit juices, fruit drinks, and fruit-flavored beverages is increasing. The impact of contemporary changes in beverage patterns on dental caries has received less attention than the impact on childhood obesity. Nevertheless, the cariogenic potential of soft drinks is known. Drinking fruit juices, fruit drinks, or fruit-flavored beverages over a long period of time and continuous sipping could therefore be harmful for the teeth. The aim of this study was to examine the sugar content of such beverages. METHODOLOGY: Four different major supermarkets were visited to select a representative sample of beverages for sale. Fruit juices, nectars, fruit drinks (water and fruit juices) and fruit-flavored waters were included. Lemonades, teas, and drinks containing artificial sweetener were not included. The data were collected in April 2010 by reading nutrition labels. The variables studied were the sugar content (g/100mL), the presence of added sugar, and the percentage of fruit juices. A descriptive analysis of the variables studied was conducted. The mean sugar content of the French population's favorite juices (orange, grapefruit, pineapple, apple, and grape) was compared to the sugar content of a corresponding 100-g portion of fresh fruit. The data were processed using Microsoft Excel. RESULTS: Hundred and eighty-seven different beverages were analyzed: 89 fruit juices, 26 nectars, 51 fruit drinks (sparkling or flat), and 21 fruit-flavored waters. Unlike fruit-flavored waters, nectars and fruit drinks contained fruit juices. Nectars and fruit drinks contained an average of 44.5% (± 10.7%) and 10.5% (± 3.8%) fruit juice, respectively. The sugar content varied from 0 g/100mL to 17.5 g/100mL. The average sugar content was 2.4 (± 2.1) g/100mL, 8.8 (± 2.3) g/100mL, 10.7 (± 1.9) g/100mL, and 10.8 (± 1) g/100mL for fruit-flavored waters, fruit drinks, fruit juices, and nectars, respectively. High sugar content was reported for grape juice, with an average of 15.6 (± 1.9) g/100mL. Nectars, fruit drinks, and 71.4% of fruit-flavored waters contained added sugar. CONCLUSION: These beverages are rich in sugar and labels should better inform consumers on the sugar content. Dental caries is a chronic disease of childhood, which has common risk factors with obesity. General practitioners, dieticians, and dentists must work together to provide preventive guidance: fruit juice intake has to be limited and other beverages restricted to occasional use; fruit juice may contribute to only one portion of the recommended five a day.

RGK GTPase-dependent CaV2.1 Ca2+ channel inhibition is independent of CaVbeta-subunit-induced current potentiation.

RGK (Rad-Gem-Rem) GTPases have been described as potent negative regulators of the Ca(2+) influx via high-threshold voltage-activated Ca(2+) channels. Recent work, mostly performed on Ca(V)1.2 Ca(2+) channels, has highlighted the crucial role played by the channel auxiliary Ca(V)beta subunits and identified several GTPase and beta-subunit protein domains involved in this regulation. We now extend these conclusions by producing the first complete characterization of the effects of Gem, Rem, and Rem2 on the neuronal Ca(V)2.1 Ca(2+) channels expressed with Ca(V)beta(1) or Ca(V)beta(2) subunits. Current inhibition is limited to a decrease in amplitude with no modification in the voltage dependence or kinetics of the current. We demonstrate that this inhibition can occur for Ca(V)beta constructs with impaired capacity to induce current potentiation, but that it is lost for Ca(V)beta constructs deleted for their beta-interaction domain. The RGK C-terminal last approximately 80 amino acids are sufficient to allow potent current inhibition and in vivo beta-subunit/Gem interaction. Interestingly, although Gem and Gem carboxy-terminus induce a completely different pattern of beta-subunit cellular localization, they both potently inhibit Ca(V)2.1 channels. These data therefore set the status of neuronal Ca(V)2.1 Ca(2+) channel inhibition by RGK GTPases, emphasizing the role of short amino acid sequences of both proteins in beta-subunit binding and channel inhibition and revealing a new mechanism for channel inhibition.

Bioaccumulation of palladium by Desulfovibrio fructosivorans wild-type and hydrogenase-deficient strains.

Wild-type Desulfovibrio fructosivorans and three hydrogenase-negative mutants reduced Pd(II) to Pd(0). The location of Pd(0) nanoparticles on the cytoplasmic membrane of the mutant retaining only cytoplasmic membrane-bound hydrogenase was strong evidence for the role of hydrogenases in Pd(0) deposition. Hydrogenase activity was retained at acidic pH, shown previously to favor Pd(0) deposition.

Grain characterization and milling behaviour of near-isogenic lines differing by hardness.

Wheat grain hardness is a major factor affecting the milling behaviour and end-product quality although its exact structural and biochemical basis is still not understood. This study describes the development of new near-isogenic lines selected on hardness. Hard and soft sister lines were characterised by near infrared reflectance (NIR) and particle size index (PSI) hardness index, grain protein content, thousand kernel weight and vitreousness. The milling behaviour of these wheat lines was evaluated on an instrumented micromill which also measures the grinding energy and flour particle size distribution was investigated by laser diffraction. Endosperm mechanical properties were measured using compression tests. Results pointed out the respective effect of hardness and vitreousness on those characteristics. Hardness was shown to influence both the mode of fracture and the mechanical properties of the whole grain and endosperm. Thus, this parameter also acts on milling behaviour. On the other hand, vitreousness was found to mainly play a role on the energy required to break the grain. This study allows us to distinguish between consequences of hardness and vitreousness. Hardness is suggested to influence the adhesion forces between starch granules and protein matrix whereas vitreousness would rather be related to the endosperm microstructure.

Voltage- and calcium-dependent inactivation in high voltage-gated Ca(2+) channels.

Calcium influx into cardiac myocytes via voltage-gated Ca channels is a key step in initiating the contractile response. During prolonged depolarizations, toxic Ca(2+) overload is prevented by channel inactivation occurring through two different processes identified by their primary trigger: voltage or intracellular Ca(2+). In physiological situations, cardiac L-type (Ca(V)1.2) Ca(2+) channels inactivate primarily via Ca(2+)-dependent inactivation (CDI), while neuronal P/Q (Ca(V)2.1) Ca(2+) channels use preferentially voltage-dependent inactivation (VDI). In certain situations however, these two types of channels have been shown to be able to inactivate by both processes. From a structural view point, the rearrangement occurring during CDI and VDI is not precisely known, but functional studies have underlined the role played by at least 2 channel sequences: a C-terminal binding site for the Ca(2+) sensor calmodulin, essential for CDI, and the loop connecting domains I and II, essential for VDI. The conserved regulation of VDI and CDI by the auxiliary channel beta subunit strongly suggests that these two mechanisms may use a set of common protein-protein interactions that are influenced by the auxiliary subunit. We will review our current knowledge of these interactions. New data are presented on L-P/Q (Ca(V)1.2/Ca(V)2.1) channel chimera that confirm the role of the I-II loop in VDI and CDI, and reveal some of the essential steps in Ca(2+) channel inactivation.

Detection and mapping of QTL for earliness components in a bread wheat recombinant inbred lines population.

Earliness, an adaptative trait and factor of variation for agronomic characters, is a major trait in plant breeding. Its constituent traits, photoperiod sensitivity (PS), vernalization requirement (VR) and intrinsic earliness (IE), are largely under independent genetic controls. Mapping of major genes and quantitative trait loci (QTL) controlling these components is in progress. Most of the studies focusing on earliness considered it as a whole or through one (or two) of its components. The purpose of this study was to detect and map QTL for the three traits together through an experimental design combining field trials and controlled growth conditions. QTL were mapped in a population of F(7) recombinant inbred lines derived by single-seed descent from a cross between two French varieties, 'Renan' and 'Recital'. A map was previously constructed, based on 194 lines and 254 markers, covering about 77% of the genome. Globally, 13 QTL with a LOD>2.5 were detected, of which four control PS, five control VR and four control IE. Two major photoperiod sensitive QTL, together explaining more than 31% of the phenotypic variation, were mapped on chromosomes 2B and 2D, at the same position as the two major genes Ppd-B1 and Ppd-D1. One major VR QTL explaining (depending on the year) 21.8-39.6% of the phenotypic variation was mapped on 5A. Among the other QTL, two QTL of PS and VR not referenced so far were detected on 5A and 6D, respectively. A VR QTL already detected on 2B in a connected population was confirmed.

Ca2+-dependent interaction of BAPTA with phospholipids.

Starting from a comparative study of different Ca2+ chelators on the G-protein-induced inhibition of the CaV2.1 Ca channels, we demonstrate that BAPTA and DM-nitrophen are able to interact, in a Ca2+- and lipid-dependent manner, with phospholipid monolayers. Critical insertion pressure and sensitivity to charged lipids indicated that insertion in the lipid film may occur in biological membranes as those found on Xenopus oocytes. This novel property is not found for EGTA and EDTA and may participate to the unusual ability of BAPTA-related molecules to chelate Ca2+ ions in the very close vicinity of the plasma membrane, where most of the Ca2+-dependent signalling triggered by voltage-gated Ca2+ currents occurs.