Epidemiology and molecular characterization of adult genetic myopathies in a southeastern region of Spain

INTRODUCTION

Genetic myopathies constitute a collection of rare diseases that significantly impact patient functionality and quality of life. Early diagnosis of genetic myopathies can prevent future complications and provide families with genetic counselling. Despite the substantial impact of genetic myopathies on the adult population, the global epidemiology of these disorders is inadequately addressed in the literature.

AIMS

To enhance understanding of both the epidemiology and genetics of these disorders within the province of Alicante, situated in southeastern Spain.

MATERIAL AND METHODS

Between 2020 and 2022, a prospective observational study was conducted at the Alicante Health Area-General Hospital, enrolling patients aged 16 years or older with suspected genetic myopathies. Sociodemographic, clinical, and genetic data were collected. The reference date for prevalence calculation was established as December 31, 2022. Official demographic data of the health area were used to set the population at risk.

RESULTS

In total, 83 patients were identified with confirmed genetically related myopathy, resulting in an overall prevalence of 29.59 cases per 100,000 inhabitants. The diagnostic yield for molecular genetic testing was found to be 69.16%. The most prevalent genetic myopathies identified included myotonic dystrophy (27.5%), dystrophinopathies (15.7%), and facioscapulohumeral dystrophy (15.7%).

CONCLUSION

The prevalence of GMs can vary considerably depending on the geographical region and the studied population. The analysis of diagnostic yield suggests that genetic studies should be considered useful in the diagnosis of genetic myopathies.

Detection and distribution of two dominant alleles associated with the sweet kernel phenotype in almond cultivated germplasm

Almond [Prunus dulcis Miller (D. A. Webb), syn. Prunus amygdalus L.)] is the major tree nut crop worldwide in terms of production and cultivated area. Almond domestication was enabled by the selection of individuals bearing sweet kernels, which do not accumulate high levels of the toxic cyanogenic glucoside amygdalin. Previously, we showed that the Sweet kernel (Sk) gene, controlling the kernel taste in almond, encodes a basic helix loop helix (bHLH) transcription factor regulating the amygdalin biosynthetic pathway. In addition, we characterized a dominant allele of this gene, further referred to as Sk-1, which originates from a C¹⁰³⁶→T missense mutation and confers the sweet kernel phenotype. Here we provide evidence indicating that the allele further referred to as Sk-2, originally detected in the cultivar "Atocha" and arising from a T⁹⁸⁹→G missense mutation, is also dominantly inherited and confers the sweet kernel phenotype in almond cultivated germplasm. The use of single nucleotide polymorphism (SNP) data from genotyping by sequencing (GBS) for population structure and hierarchical clustering analyses indicated that Sk-2 occurs in a group of related genotypes, including the widespread cultivar "Texas", descending from the same ancestral population. KASP and dual label functional markers were developed for the accurate and high-throughput selection of the Sk-1 and Sk-2 alleles, and the genotyping of a panel of 134 almond cultivars. Overall, our results provide further insights on the understanding of the almond cultivation history. In addition, molecular marker assays and genotypic data presented in this study are expected to be of major interest for the conduction of almond breeding programs, which often need to select sweet kernel individuals in segregant populations.

Advancing Endodormancy Release in Temperate Fruit Trees Using Agrochemical Treatments

Endodormancy in temperate fruit trees like Prunus is a protector state that allows the trees to survive in the adverse conditions of autumn and winter. During this process, plants accumulate chill hours. Flower buds require a certain number of chill hours to release from endodormancy, known as chilling requirements. This step is crucial for proper flowering and fruit set, since incomplete fulfillment of the chilling requirements produces asynchronous flowering, resulting in low quality flowers, and fruits. In recent decades, global warming has endangered this chill accumulation. Because of this fact, many agrochemicals have been used to promote endodormancy release. One of the first and most efficient agrochemicals used for this purpose was hydrogen cyanamide. The application of this agrochemical has been found to advance endodormancy release and synchronize flowering time, compressing the flowering period and increasing production in many species, including apple, grapevine, kiwi, and peach. However, some studies have pointed to the toxicity of this agrochemical. Therefore, other non-toxic agrochemicals have been used in recent years. Among them, Erger^® + Activ Erger^® and Syncron^® + NitroActive^® have been the most popular alternatives. These two treatments have been shown to efficiently advance endodormancy release in most of the species in which they have been applied. In addition, other less popular agrochemicals have also been applied, but their efficiency is still unclear. In recent years, several studies have focused on the biochemical and genetic variation produced by these treatments, and significant variations have been observed in reactive oxygen species, abscisic acid (ABA), and gibberellin (GA) levels and in the genes responsible for their biosynthesis. Given the importance of this topic, future studies should focus on the discovery and development of new environmentally friendly agrochemicals for improving the modulation of endodormancy release and look more deeply into the effects of these treatments in plants.

Identification of early and late flowering time candidate genes in endodormant and ecodormant almond flower buds

Flower bud dormancy in temperate fruit tree species, such as almond [Prunus dulcis (Mill.) D.A. Webb], is a survival mechanism that ensures that flowering will occur under suitable weather conditions for successful flower development, pollination and fruit set. Dormancy is divided into three sequential phases: paradormancy, endodormancy and ecodormancy. During the winter, buds need cultivar-specific chilling requirements (CRs) to overcome endodormancy and heat requirements to activate the machinery to flower in the ecodormancy phase. One of the main factors that enables the transition from endodormancy to ecodormancy is transcriptome reprogramming. In this work, we therefore monitored three almond cultivars with different CRs and flowering times by RNA sequencing during the endodormancy release of flower buds and validated the data by quantitative real-time PCR in two consecutive seasons. We were thus able to identify early and late flowering time candidate genes in endodormant and ecodormant almond flower buds associated with metabolic switches, transmembrane transport, cell wall remodeling, phytohormone signaling and pollen development. These candidate genes were indeed involved in the overcoming of the endodormancy in almond. This information may be used for the development of dormancy molecular markers, increasing the efficiency of temperate fruit tree breeding programs in a climate-change context.

Almond diversity and homozygosity define structure, kinship, inbreeding, and linkage disequilibrium in cultivated germplasm, and reveal genomic associations with nut and seed weight

Almond [Prunus dulcis Miller (D.A. Webb)] is the main tree nut species worldwide. Here, genotyping-by-sequencing (GBS) was applied to 149 almond cultivars from the ex situ collections of the Italian Council for Agricultural Research (CREA) and the Spanish National Research Council (CSIC), leading to the detection of 93,119 single-nucleotide polymorphisms (SNPs). The study of population structure outlined four distinct genetic groups and highlighted diversification between the Mediterranean and Californian gene pools. Data on SNP diversity and runs of homozygosity (ROHs) allowed the definition of kinship, inbreeding, and linkage disequilibrium (LD) decay in almond cultivated germplasm. Four-year phenotypic observations, gathered on 98 cultivars of the CREA collection, were used to perform a genome-wide association study (GWAS) and, for the first time in a crop species, homozygosity mapping (HM), resulting in the identification of genomic associations with nut, shell, and seed weight. Both GWAS and HM suggested that loci controlling nut and seed weight are mostly independent. Overall, this study provides insights on the almond cultivation history and delivers information of major interest for almond genetics and breeding. In a broader perspective, our results encourage the use of ROHs in crop science to estimate inbreeding, choose parental combinations minimizing the risk of inbreeding depression, and identify genomic footprints of selection for specific traits.

Ascorbic acid and prunasin, two candidate biomarkers for endodormancy release in almond flower buds identified by a nontargeted metabolomic study

Temperate fruit trees belonging to Prunus species have the ability to suspend (induce dormancy) and resume growth periodically in response to environmental and seasonal conditions. Endodormancy release requires the long-term accumulation of chill. Upon accumulation of cultivar-specific chill requirements, plants enter the state of ecodormancy, which means the ability to grow has been restored, depending on the fulfilment of heat requirements. As many different metabolic pathways are implicated in endodormancy release, we have performed a metabolomic analysis, using the ultra-high-performance liquid chromatography-quadrupole time-of-flying (UPLC-QToF) technique. We assayed flower buds in different stages of endodormancy in four almond cultivars with different flowering times: the extra-early Desmayo Largueta, the late Antoñeta, the extra-late Penta, and the ultra-late Tardona. An orthogonal projection to latent-structure discriminant-analysis model was created to observe differences between endodormant and ecodormant flower buds. The metabolites showing the most significant variation were searched against the Metlin, HMDB, and KEGG libraries, which allowed us to identify 87 metabolites. These metabolites were subsequently assigned to specific pathways, such as abscisic acid biosynthesis, phenylpropanoid biosynthesis, and D-sorbitol metabolism, among others. The two metabolites that exhibited the most significant variations in all the cultivars studied with fold changes of up to 6.49 were ascorbic acid and prunasin. For the first time, these two metabolites have been proposed as potential biomarkers for endodormancy release in almond. Given the high synteny present between the Rosaceae species, these results could be extrapolated to other important crops like peach, plum, cherry, or apricot, among others.

[Drug exposure associated with exacerbation of symptoms in patients with myasthenia gravis]

INTRODUCTION

Numerous drugs have been related to exacerbation of myasthenia gravis. So far there are no studies examining the extent of use of drugs related to exacerbation of myasthenia gravis.

AIMS

We sought to assess the extent of use of drugs related to exacerbations and the annual incidence rate of exacerbations in a cohort of myasthenia gravis patients. We explored possible risk factors of severe exacerbations.

PATIENTS AND METHODS

We performed a retrospective cohort study. We included adult patients followed in neurology department. We estimated frequencies, rates and built a recurrent events model.

RESULTS

We included 91 patients. 94.51% of patients had at least one prescription of a drug. 51 patients had at least one prescription of a drug contraindicated according to its drug label. 145 exacerbation episodes were reported in 50 patients. The annual incidence rate of exacerbation episodes was 0.35. 48 exacerbations were severe (in 18 patients). The annual incidence rate of severe exacerbation episodes was 0.12. Generalized myasthenia gravis and thymectomy were associated with a higher risk of severe exacerbation episodes.

CONCLUSIONS

Our patients were extensive and widespread exposed to drugs during the follow-up period but we did not find and association with severe exacerbation episodes. Just over half of the patients had at least one exacerbation episode during the study period, most of them were mild. Further studies with larger sample sizes are necessary to corroborate these conclusions and to study possible correlations between the use of drugs and the risk of exacerbation episodes.

Mutation of a bHLH transcription factor allowed almond domestication

Wild almond species accumulate the bitter and toxic cyanogenic diglucoside amygdalin. Almond domestication was enabled by the selection of genotypes harboring sweet kernels. We report the completion of the almond reference genome. Map-based cloning using an F₁ population segregating for kernel taste led to the identification of a 46-kilobase gene cluster encoding five basic helix-loop-helix transcription factors, bHLH1 to bHLH5. Functional characterization demonstrated that bHLH2 controls transcription of the P450 monooxygenase-encoding genes PdCYP79D16 and PdCYP71AN24, which are involved in the amygdalin biosynthetic pathway. A nonsynonymous point mutation (Leu to Phe) in the dimerization domain of bHLH2 prevents transcription of the two cytochrome P450 genes, resulting in the sweet kernel trait.

Elucidation of the Amygdalin Pathway Reveals the Metabolic Basis of Bitter and Sweet Almonds (Prunus dulcis)

Almond (Prunus dulcis) is the principal Prunus species in which the consumed and thus commercially important part of the fruit is the kernel. As a result of continued selection, the vast majority of almonds have a nonbitter kernel. However, in the field, there are trees carrying bitter kernels, which are toxic to humans and, consequently, need to be removed. The toxicity of bitter almonds is caused by the accumulation of the cyanogenic diglucoside amygdalin, which releases toxic hydrogen cyanide upon hydrolysis. In this study, we identified and characterized the enzymes involved in the amygdalin biosynthetic pathway: PdCYP79D16 and PdCYP71AN24 as the cytochrome P450 (CYP) enzymes catalyzing phenylalanine-to-mandelonitrile conversion, PdUGT94AF3 as an additional monoglucosyl transferase (UGT) catalyzing prunasin formation, and PdUGT94AF1 and PdUGT94AF2 as the two enzymes catalyzing amygdalin formation from prunasin. This was accomplished by constructing a sequence database containing UGTs known, or predicted, to catalyze a β(1→6)-O-glycosylation reaction and a Basic Local Alignment Search Tool search of the draft version of the almond genome versus these sequences. Functional characterization of candidate genes was achieved by transient expression in Nicotiana benthamiana Reverse transcription quantitative polymerase chain reaction demonstrated that the expression of PdCYP79D16 and PdCYP71AN24 was not detectable or only reached minute levels in the sweet almond genotype during fruit development, while it was high and consistent in the bitter genotype. Therefore, the basis for the sweet kernel phenotype is a lack of expression of the genes encoding the two CYPs catalyzing the first steps in amygdalin biosynthesis.

Synteny-Based Development of CAPS Markers Linked to the Sweet kernel LOCUS, Controlling Amygdalin Accumulation in Almond (Prunus dulcis (Mill.) D.A.Webb)

The bitterness and toxicity of wild-type seeds of Prunoideae is due to the cyanogenic glucoside amygdalin. In cultivated almond (Prunus dulcis (Mill.) D.A. Webb), a dominant mutation at the Sk locus prevents amygdalin accumulation and thus results in edible sweet kernels. Here, we exploited sequence similarity and synteny between the genomes of almond and peach (Prunus persica (L.) Batsch) to identify cleaved amplified polymorphic sequence (CAPS) molecular markers linked to the Sk locus. A segregant F₁ population was used to map these markers on the Sk genomic region, together with Sk-linked simple sequence repeat (SSR) markers previously described. Molecular fingerprinting of a cultivar collection indicated the possibility to use CAPS polymorphisms identified in this study in breeding programs arising from different parental combinations. Overall, we highlight a set of codominant markers useful for early selection of sweet kernel genotypes, an aspect of primary importance in almond breeding. In addition, by showing collinearity between the physical map of peach and the genetic map of almond with respect to the Sk genomic region, we provide valuable information for further marker development and Sk positional cloning.

β-Glucosidase activity in almond seeds

Almond bitterness is the most important trait for breeding programs since bitter-kernelled seedlings are usually discarded. Amygdalin and its precursor prunasin are hydrolyzed by specific enzymes called β-glucosidases. In order to better understand the genetic control of almond bitterness, some studies have shown differences in the location of prunasin hydrolases (PH, the β-glucosidase that degrades prunasin) in sweet and bitter genotypes. The aim of this work was to isolate and characterize different PHs in sweet- and bitter-kernelled almonds to determine whether differences in their genomic or protein sequences are responsible for the sweet or bitter taste of their seeds. RNA was extracted from the tegument, nucellus and cotyledon of one sweet (Lauranne) and two bitter (D05-187 and S3067) almond genotypes throughout fruit ripening. Sequences of nine positive Phs were then obtained from all of the genotypes by RT-PCR and cloning. These clones, from mid ripening stage, were expressed in a heterologous system in tobacco plants by agroinfiltration. The PH activity was detected using the Feigl-Anger method and quantifying the hydrogen cyanide released with prunasin as substrate. Furthermore, β-glucosidase activity was detected by Fast Blue BB salt and Umbelliferyl method. Differences at the sequence level (SNPs) and in the activity assays were detected, although no correlation with bitterness was found.

Transcriptome and Metabolite Changes during Hydrogen Cyanamide-Induced Floral Bud Break in Sweet Cherry

Release of bud dormancy in perennial woody plants is a temperature-dependent process and thus flowering in these species is heavily affected by climate change. The lack of cold winters in temperate growing regions often results in reduced flowering and low fruit yields. This is likely to decrease the availability of fruits and nuts of the Prunus spp. in the near future. In order to maintain high yields, it is crucial to gain detailed knowledge on the molecular mechanisms controlling the release of bud dormancy. Here, we studied these mechanisms using sweet cherry (Prunus avium L.), a crop where the agrochemical hydrogen cyanamide (HC) is routinely used to compensate for the lack of cold winter temperatures and to induce flower opening. In this work, dormant flower buds were sprayed with hydrogen cyanamide followed by deep RNA sequencing, identifying three main expression patterns in response to HC. These transcript level results were validated by quantitative real time polymerase chain reaction and supported further by phytohormone profiling (ABA, SA, IAA, CK, ethylene, JA). Using these approaches, we identified the most up-regulated pathways: the cytokinin pathway, as well as the jasmonate and the hydrogen cyanide pathway. Our results strongly suggest an inductive effect of these metabolites in bud dormancy release and provide a stepping stone for the characterization of key genes in bud dormancy release.

Cyanogenic Glucosides and Derivatives in Almond and Sweet Cherry Flower Buds from Dormancy to Flowering

Almond and sweet cherry are two economically important species of the Prunus genus. They both produce the cyanogenic glucosides prunasin and amygdalin. As part of a two-component defense system, prunasin and amygdalin release toxic hydrogen cyanide upon cell disruption. In this study, we investigated the potential role within prunasin and amygdalin and some of its derivatives in endodormancy release of these two Prunus species. The content of prunasin and of endogenous prunasin turnover products in the course of flower development was examined in five almond cultivars - differing from very early to extra-late in flowering time - and in one sweet early cherry cultivar. In all cultivars, prunasin began to accumulate in the flower buds shortly after dormancy release and the levels dropped again just before flowering time. In almond and sweet cherry, the turnover of prunasin coincided with increased levels of prunasin amide whereas prunasin anitrile pentoside and β-D-glucose-1-benzoate were abundant in almond and cherry flower buds at certain developmental stages. These findings indicate a role for the turnover of cyanogenic glucosides in controlling flower development in Prunus species.

Bottom-Up Elucidation of Glycosidic Bond Stereochemistry

The lack of robust, high-throughput, and sensitive analytical strategies that can conclusively map the structure of glycans has significantly hampered progress in fundamental and applied aspects of glycoscience. Resolution of the anomeric α/β glycan linkage within oligosaccharides remains a particular challenge. Here, we show that "memory" of anomeric configuration is retained following gas-phase glycosidic bond fragmentation during tandem mass spectrometry (MS²). These findings allow for integration of MS² with ion mobility spectrometry (IM-MS²) and lead to a strategy to distinguish α- and β-linkages within natural underivatized carbohydrates. We have applied this fragment-based hyphenated MS technology to oligosaccharide standards and to de novo sequencing of purified plant metabolite glycoconjugates, showing that the anomeric signature is also observable in fragments derived from larger glycans. The discovery of the unexpected anomeric memory effect is further supported by IR-MS action spectroscopy and ab initio calculations. Quantum mechanical calculations provide candidate geometries for the distinct anomeric fragment ions, in turn shedding light on gas-phase dissociation mechanisms of glycosidic linkages.

Chemical control of flowering time

Flowering at the right time is of great importance; it secures seed production and therefore species survival and crop yield. In addition to the genetic network controlling flowering time, there are a number of much less studied metabolites and exogenously applied chemicals that may influence the transition to flowering as well as flower opening. Increased emphasis on research within this area has the potential to counteract the negative effects of global warming on flowering time, especially in perennial crop plants. Perennial crops have a requirement for winter chill, but winters become increasingly warm in temperate regions. This has dramatic effects on crop yield. Different strategies are therefore being developed to engineer flowering time to match local growing conditions. The majority of these efforts are within plant breeding, which benefits from a substantial amount of knowledge on the genetic aspects of flowering time regulation in annuals, but less so in perennials. An alternative to plant breeding approaches is to engineer flowering time chemically via the external application of flower-inducing compounds. This review discusses a variety of exogenously applied compounds used in fruit farming to date, as well as endogenous growth substances and metabolites that can influence flowering time of annuals and perennials.

Carotid atherosclerosis is not associated with lower bone mineral density and vertebral fractures in patients with systemic lupus erythematosus

Background

Low bone mineral density (BMD) and vertebral fractures (VF) have been associated with atherosclerosis in the general population. We sought to investigate the relationship between BMD and VF and carotid atherosclerosis in women with systemic lupus erythematosus (SLE).

Methods

We studied 122 women with SLE. All patients had BMD, carotid intima-media thickness (IMT), and carotid artery atherosclerotic plaque assessment by ultrasound.

Results

Mean age at study entry was 44 years and mean disease duration was 11 years. Carotid plaque was found in 13 (11%) patients (9 postmenopausal and 4 premenopausal). Patients in the highest IMT quartile were more likely to be older ( p = 0.001), have a higher body mass index ( p = 0.008), and exhibit dyslipidemia at study entry ( p = 0.041), compared with the lower three quartiles. BMD at the lumbar spine was lower in patients in the highest IMT quartile compared with the lower quartiles in the multivariate logistic analysis, however, there was no association between lumbar or total hip BMD and IMT ( p = 0.91 and p = 0.6, respectively). IMT measurements did not differ according to the presence or absence of VF (0.08 ± 0.12 vs. 0.06 ± 0.03 mm, p = 0.11). A trend towards higher incidence of VF was found in patients with carotid plaque compared with those without (33% vs. 21%; p = 0.2).

Conclusions

In patients with SLE, the presence of carotid atherosclerosis is not associated with low BMD or VF.

Recent advancements to study flowering time in almond and other Prunus species

Flowering time is an important agronomic trait in almond since it is decisive to avoid the late frosts that affect production in early flowering cultivars. Evaluation of this complex trait is a long process because of the prolonged juvenile period of trees and the influence of environmental conditions affecting gene expression year by year. Consequently, flowering time has to be studied for several years to have statistical significant results. This trait is the result of the interaction between chilling and heat requirements. Flowering time is a polygenic trait with high heritability, although a major gene Late blooming (Lb) was described in "Tardy Nonpareil." Molecular studies at DNA level confirmed this polygenic nature identifying several genome regions (Quantitative Trait Loci, QTL) involved. Studies about regulation of gene expression are scarcer although several transcription factors have been described as responsible for flowering time. From the metabolomic point of view, the integrated analysis of the mechanisms of accumulation of cyanogenic glucosides and flowering regulation through transcription factors open new possibilities in the analysis of this complex trait in almond and in other Prunus species (apricot, cherry, peach, plum). New opportunities are arising from the integration of recent advancements including phenotypic, genetic, genomic, transcriptomic, and metabolomics studies from the beginning of dormancy until flowering.

Comparative genomics analysis in Prunoideae to identify biologically relevant polymorphisms

Prunus is an economically important genus with a wide range of physiological and biological variability. Using the peach genome as a reference, sequencing reads from four almond accessions and one sweet cherry cultivar were used for comparative analysis of these three Prunus species. Reference mapping enabled the identification of many biological relevant polymorphisms within the individuals. Examining the depth of the polymorphisms and the overall scaffold coverage, we identified many potentially interesting regions including hundreds of small scaffolds with no coverage from any individual. Non-sense mutations account for about 70 000 of the 13 million identified single nucleotide polymorphisms (SNPs). Blast2GO analyses on these non-sense SNPs revealed several interesting results. First, non-sense SNPs were not evenly distributed across all gene ontology terms. Specifically, in comparison with peach, sweet cherry is found to have non-sense SNPs in two 1-aminocyclopropane-1-carboxylate synthase (ACS) genes and two 1-aminocyclopropane-1-carboxylate oxidase (ACO) genes. These polymorphisms may be at the root of the nonclimacteric ripening of sweet cherry. A set of candidate genes associated with bitterness in almond were identified by comparing sweet and bitter almond sequences. To the best of our knowledge, this is the first report in plants of non-sense SNP abundance in a genus being linked to specific GO terms.

Prunasin hydrolases during fruit development in sweet and bitter almonds

Amygdalin is a cyanogenic diglucoside and constitutes the bitter component in bitter almond (Prunus dulcis). Amygdalin concentration increases in the course of fruit formation. The monoglucoside prunasin is the precursor of amygdalin. Prunasin may be degraded to hydrogen cyanide, glucose, and benzaldehyde by the action of the β-glucosidase prunasin hydrolase (PH) and mandelonitirile lyase or be glucosylated to form amygdalin. The tissue and cellular localization of PHs was determined during fruit development in two sweet and two bitter almond cultivars using a specific antibody toward PHs. Confocal studies on sections of tegument, nucellus, endosperm, and embryo showed that the localization of the PH proteins is dependent on the stage of fruit development, shifting between apoplast and symplast in opposite patterns in sweet and bitter cultivars. Two different PH genes, Ph691 and Ph692, have been identified in a sweet and a bitter almond cultivar. Both cDNAs are 86% identical on the nucleotide level, and their encoded proteins are 79% identical to each other. In addition, Ph691 and Ph692 display 92% and 86% nucleotide identity to Ph1 from black cherry (Prunus serotina). Both proteins were predicted to contain an amino-terminal signal peptide, with the size of 26 amino acid residues for PH691 and 22 residues for PH692. The PH activity and the localization of the respective proteins in vivo differ between cultivars. This implies that there might be different concentrations of prunasin available in the seed for amygdalin synthesis and that these differences may determine whether the mature almond develops into bitter or sweet.

Clarifying omics concepts, challenges, and opportunities for Prunus breeding in the postgenomic era

The recent sequencing of the complete genome of the peach, together with the availability of new high-throughput genome, transcriptome, proteome, and metabolome analysis technologies, offers new possibilities for Prunus breeders in what has been described as the postgenomic era. In this context, new biological challenges and opportunities for the application of these technologies in the development of efficient marker-assisted selection strategies in Prunus breeding include genome resequencing using DNA-Seq, the study of RNA regulation at transcriptional and posttranscriptional levels using tilling microarray and RNA-Seq, protein and metabolite identification and annotation, and standardization of phenotype evaluation. Additional biological opportunities include the high level of synteny among Prunus genomes. Finally, the existence of biases presents another important biological challenge in attaining knowledge from these new high-throughput omics disciplines. On the other hand, from the philosophical point of view, we are facing a revolution in the use of new high-throughput analysis techniques that may mean a scientific paradigm shift in Prunus genetics and genomics theories. The evaluation of scientific progress is another important question in this postgenomic context. Finally, the incommensurability of omics theories in the new high-throughput analysis context presents an additional philosophical challenge.

Tissue and cellular localization of individual beta-glycosidases using a substrate-specific sugar reducing assay

Traditional methods to localize beta-glycosidase activity in tissue sections have been based on incubation with the general substrate 6-bromo-2-naphthyl-beta-d-glucopyranoside. When hydrolysed in the presence of salt zinc compounds, 6-bromo-2-naphthyl-beta-d-glucopyranoside affords the formation of an insoluble coloured product. This technique does not distinguish between different beta-glycosidases present in the tissue. To be able to monitor the occurrence of individual beta-glycosidases in different tissues and cell types, we have developed a versatile histochemical method that can be used for localization of any beta-glycosidase that upon incubation with its specific substrate releases a reducing sugar. Experimentally, the method is based on hydrolysis of the specific substrate followed by oxidation of the sugar released by a tetrazolium salt (2,3,5-triphenyltetrazolium chloride) that forms a red insoluble product when reduced. The applicability of the method was demonstrated by tissue and cellular localization of two beta-glucosidases, amygdalin hydrolase and prunasin hydrolase, in different tissues and cell types of almond. In those cases where the analysed tissue had a high content of reducing sugars, this resulted in strong staining of the background. This interfering staining of the background was avoided by prior incubation with sodium borohydride. The specificity of the devised method was demonstrated in a parallel localization study using a specific antibody towards prunasin hydrolase.

beta-Glucosidases as detonators of plant chemical defense

Some plant secondary metabolites are classified as phytoanticipins. When plant tissue in which they are present is disrupted, the phytoanticipins are bio-activated by the action of beta-glucosidases. These binary systems--two sets of components that when separated are relatively inert--provide plants with an immediate chemical defense against protruding herbivores and pathogens. This review provides an update on our knowledge of the beta-glucosidases involved in activation of the four major classes of phytoanticipins: cyanogenic glucosides, benzoxazinoid glucosides, avenacosides and glucosinolates. New aspects of the role of specific proteins that either control oligomerization of the beta-glucosidases or modulate their product specificity are discussed in an evolutionary perspective.

Bitterness in almonds

Bitterness in almond (Prunus dulcis) is determined by the content of the cyanogenic diglucoside amygdalin. The ability to synthesize and degrade prunasin and amygdalin in the almond kernel was studied throughout the growth season using four different genotypes for bitterness. Liquid chromatography-mass spectrometry analyses showed a specific developmentally dependent accumulation of prunasin in the tegument of the bitter genotype. The prunasin level decreased concomitant with the initiation of amygdalin accumulation in the cotyledons of the bitter genotype. By administration of radiolabeled phenylalanine, the tegument was identified as a specific site of synthesis of prunasin in all four genotypes. A major difference between sweet and bitter genotypes was observed upon staining of thin sections of teguments and cotyledons for beta-glucosidase activity using Fast Blue BB salt. In the sweet genotype, the inner epidermis in the tegument facing the nucellus was rich in cytoplasmic and vacuolar localized beta-glucosidase activity, whereas in the bitter cultivar, the beta-glucosidase activity in this cell layer was low. These combined data show that in the bitter genotype, prunasin synthesized in the tegument is transported into the cotyledon via the transfer cells and converted into amygdalin in the developing almond seed, whereas in the sweet genotype, amygdalin formation is prevented because the prunasin is degraded upon passage of the beta-glucosidase-rich cell layer in the inner epidermis of the tegument. The prunasin turnover may offer a buffer supply of ammonia, aspartic acid, and asparagine enabling the plants to balance the supply of nitrogen to the developing cotyledons.

[Clinical features of migraine according to the questionnaire 'Alcoi-92' in the Comtat area]

INTRODUCTION

Headache is one of the commonest reasons for consultation and it might be useful to know its characteristics in order to determine which patients may need medical attention.

OBJECTIVES

To carry out a randomized transverse study in a rural population using the validated questionnaire 'Alcoi-92', and to determine the clinical characteristics of the headaches detected.

PATIENTS AND METHODS

A door to door survey was done by randomized selection of 790 persons aged over 18 and living in the Comarca del Comtat. A validated self-questionnaire was sent and this was followed by an interview with a doctor.

RESULTS

Five hundred and forty-eight persons were interviewed. The standard prevalence of migraine is 19.6% with a sex incidence of 1:2.4 and an average age of 46.1 years. The average age of onset was 20.64 years. There were family histories of cerebrovascular accidents in 26.4% and of migraine in 57.1%. There were no differences in the use of toxic substances, of socio-economic status or of marital status. The commonest pre-existing pathology was arterial hypertension. The number of episodes of headache was one to seven per year in 50% of those with migraine, with an average duration of 4-24 hours, predominantly bilateral presentation and pulsatile in character with moderate repercussion in everyday activities. The commonest associated symptoms were photophobia and sonophobia. There were prodromal symptoms in 36.9%, most commonly confusion and photopsy.

CONCLUSION

The questionnaire 'Alcoi-92' has been shown to be a useful tool for definition of the clinical characteristics of migraine.

[A descriptive study of migraine in a rural population of Area del Comtat]

INTRODUCTION

Headache is one of the commonest causes of consultation in neurology. There are many studies of the prevalence of migraine showing considerable variation in the results obtained.

OBJECTIVES

To find the prevalence of migraine, with and without an aura, by means of a randomized transverse study carried out in a previously selected rural population, using the validated questionnaire 'Alcoi-92'. To find the overall prevalence of migraine, specifically regarding age and sex and adjusted for the European population.

PATIENTS AND METHODS

A door-to-door study was made by random selection of 790 persons aged over 18, in three towns in the comarca del Comtat, Alacant, Spain. A self-questionnaire was sent to all persons studies and subsequently they were seen by a medical interviewer.

RESULTS

We interviewed 548 persons (overall response rate 78%). The average age was 52.5 +/- 19.3 years. Sex distribution of the population interviewed showed a predominance of females (52.9%) as compared to males (47.1%). According to the type of headache: other types of headache 62.32%, persons with no previous history of headache 20.07%, amplified migraine 16.6%, typical migraine 12.6%, cluster type migraine 0.18%.

CONCLUSIONS

The overall prevalence of amplified migraine was 16.6%. According to diagnostic groups the frequency of migraine with aura was 2.9%, migraine without aura 9.7% and typical migraine 12.6%. A predominance of women was seen in all types of migraine. The frequency of migraine, adjusted for the European population was 19.6%. Prevalence during the past year, as a measure of activity of the disorder was 15.7%.