Selection index and molecular markers in reciprocal recurrent selection in maize

Reciprocal recurrent selection among full-sib families is one of the outstanding methodologies of maizeimprovement, since gains are possible in the per se and/or in cross populations. Here the selection index proposed by Smithand Hazel was used in the cited methodology; besides, an additional phase involving RAPD markers was introduced topreserve the genetic variability of the selected genotypes and identify contaminants before their recombination. Multivariatetechniques of grouping and discriminant analyses were used for this purpose, to assure the continuance of the improvementprogram and amplify the genetic distance between the populations Cimmyt and Piranão, which were used for an intervarietalhybrid. The molecular technique proved useful to identify contaminants and helpful in the choice of the genotypes to berecombined to maximize heterosis among populations. The technique can be included in recurrent selection programs, mainlythose that target the development of hybrids

Label-Free Quantitative Proteomics of Embryogenic and Non-Embryogenic Callus during Sugarcane Somatic Embryogenesis

<div><p>The development of somatic cells in to embryogenic cells occurs in several stages and ends in somatic embryo formation, though most of these biochemical and molecular changes have yet to be elucidated. Somatic embryogenesis coupled with genetic transformation could be a biotechnological tool to improve potential crop yields potential in sugarcane cultivars. The objective of this study was to observe somatic embryo development and to identify differentially expressed proteins in embryogenic (E) and non-embryogenic (NE) callus during maturation treatment. E and NE callus were cultured on maturation culture medium supplemented with different concentrations (0.0, 0.75, 1.5 and 2.0 g L^-1) of activated charcoal (AC). Somatic embryo formation and differential protein expression were evaluated at days 0 and 21 using shotgun proteomic analyses. Treatment with 1.5 g L^-1 AC resulted in higher somatic embryo maturation rates (158 somatic embryos in 14 days) in E callus but has no effect in NE callus. A total of 752 co-expressed proteins were identified through the SUCEST (The Sugarcane EST Project), including many housekeeping proteins. E callus showed 65 exclusive proteins on day 0, including dehydrogenase, desiccation-related protein, callose synthase 1 and nitric oxide synthase. After 21 days on maturation treatment, 14 exclusive proteins were identified in E callus, including catalase and secreted protein. NE callus showed 23 exclusive proteins on day 0 and 10 exclusive proteins after 21 days on maturation treatment, including many proteins related to protein degradation. The induction of maturation leads to somatic embryo development, which likely depends on the expression of specific proteins throughout the process, as seen in E callus under maturation treatment. On the other hand, some exclusive proteins can also specifically prevent of somatic embryos development, as seen in the NE callus.</p></div

Unique proteins that were identified in embryogenic (E) or non-embryogenic (NE) sugarcane callus under maturation treatment.

<p>Confidence scores were calculated by ProteinLynx Global Server (PLGS).</p><p>Unique proteins that were identified in embryogenic (E) or non-embryogenic (NE) sugarcane callus under maturation treatment.</p

Pie charts showing the functional classification of the co-expressed proteins.

<p>Functional classification of the co-expressed proteins from embryogenic (E) and non-embryogenic (NE) callus before (0) and after 21 days of maturation treatment (E-0, E-21, NE-0 and NE-21).</p

Venn diagram and pie charts displaying the numbers and functions of unique and co-expressed proteins.

<p>The number of unique and co-expressed proteins from embryogenic(E) and non-embryogenic (NE) callus during maturation treatment and the functional classification of unique proteins from embryogenic (E) and non-embryogenic (NE) callus at 0 and 21 days of maturation treatment (E-0, E-21, NE-0 and NE-21).</p

Alpha-glucosidase promotes hemozoin formation in a blood-sucking bug: An evolutionary history

Background: Hematophagous insects digest large amounts of host hemoglobin and release heme inside their guts. In Rhodnius prolixus, hemoglobin-derived heme is detoxified by biomineralization, forming hemozoin (Hz). Recently, the involvement of the R. prolixus perimicrovillar membranes in Hz formation was demonstrated. Methodology/Principal Findings: Hz formation activity of an α-glucosidase was investigated. Hz formation was inhibited by specific α-glucosidase inhibitors. Moreover, Hz formation was sensitive to inhibition by Diethypyrocarbonate, suggesting a critical role of histidine residues in enzyme activity. Additionally, a polyclonal antibody raised against a phytophagous insect α-glucosidase was able to inhibit Hz formation. The α-glucosidase inhibitors have had no effects when used 10 h after the start of reaction, suggesting that α-glucosidase should act in the nucleation step of Hz formation. Hz formation was seen to be dependent on the substrate-binding site of enzyme, in a way that maltose, an enzyme substrate, blocks such activity. dsRNA, constructed using the sequence of α-glucosidase gene, was injected into R. prolixus females' hemocoel. Gene silencing was accomplished by reduction of both α-glucosidase and Hz formation activities. Insects were fed on plasma or hemin-enriched plasma and gene expression and activity of α-glucosidase were higher in the plasma plus hemin-fed insects. The deduced amino acid sequence of α-glucosidase shows a high similarity to the insect α-glucosidases, with critical histidine and aspartic residues conserved among the enzymes. Conclusions/Significance: Herein the Hz formation is shown to be associated to an a-glucosidase, the biochemical marker from Hemipteran perimicrovillar membranes. Usually, these enzymes catalyze the hydrolysis of glycosidic bond. The results strongly suggest that α-glucosidase is responsible for Hz nucleation in the R. prolixus midgut, indicating that the plasticity of this enzyme may play an important role in conferring fitness to hemipteran hematophagy, for instance. © 2009 Mury et al