<Emphasis Type="Italic">UGP</Emphasis> gene expression and UDP-glucose pyrophosphorylase enzymatic activity in grafting annonaceous plants

Grafting is commonly used to propagate commercial fruit species to ensure that the genetic characteristics of selected clones are maintained. However, the biochemical and molecular mechanisms involved in the graft incompatibility of woody trees are not well understood. We investigated the effect of grafting in vegetative growth, UDP-glucose pyrophosphorylase expression and activity of Annonaceous grafted plants: atemoya (Annona cherimola Mill. x Annona squamosa L.) ‘Thompson’ grafted onto different rootstocks, araticum-de-terra-fria (Annona emarginata Schltdl. H. Rainer “var. terra-fria”), araticum-mirim (Annona emarginata Schltdl. H. Rainer “var. mirim”) and biribá (Annona mucosa Schltdl. H. Rainer) at different post-grafting times. The growth of atemoya grafted onto araticum-mirim was lower than that of the rootstocks araticum-de terra-fria and biribá. The results also indicated that grafting alters UGPase gene expression; showing the combination atemoya grafted onto araticum-de-terra-fria (a compatible union) the higher levels of gene expression during the early stages of grafting development. However, no significant differences were detected in UGPase enzyme activity between the graft combinations. In addition, SDS-PAGE and MALDI-TOF analyses detected similar UGPase amino acid sequences in ungrafted atemoya samples to cherimoya (Annona cherimola Mill.), a female parent of the atemoya hybrid. These findings suggest that expression of the UGPase protein is related to graft compatibility in grafted Annona plants.     

Effect of EEG Biofeedback on Cognitive Flexibility in Children with Attention Deficit Hyperactivity Disorder With and Without Epilepsy

Attention deficit hyperactivity disorder (ADHD) is one of the most common developmental disorders in school-aged children. Symptoms consistent with ADHD have been observed in 8–77 % of children with epilepsy. Researchers have been motivated to search for alternative forms of treatment because 30 % of patients with ADHD cannot be treated by psychostimulants. Several studies support the use of a multimodal treatment approach that includes neurofeedback (NF) for the long-term management of ADHD. These studies have shown that NF provides a sustained effect, even without concurrent treatment with stimulants. We aimed to assess cognitive flexibility in ADHD children with and without temporal lobe epilepsy (TLE), and to evaluate the effects of NF on cognitive flexibility in these groups of children. We prospectively evaluated 69 patients with ADHD aged 9–12 years. The control group was 26 ADHD children without TLE who received no treatment. The first experimental group comprised 18 children with ADHD. The second experimental group comprised 25 age-matched ADHD children with TLE. This group was further divided in two subgroups. One subgroup comprised those with mesial temporal lobe epilepsy (16 patients, 9 with hippocampal sclerosis and 7 with hippocampal atrophy), and the other with lateral temporal lobe epilepsy (9 patients, 5 with temporal lobe dysplasia, 3 with temporal lobe cysts, and 1 with a temporal lobe cavernoma). We treated their ADHD by conducting 30 sessions of EEG NF. Reaction time and error rates on the Trail Making Test Part B were compared before and after treatment, and significant differences were found for all groups of patients except those who had mesial temporal lobe epilepsy with hippocampal atrophy. Our results demonstrate that in most cases, NF can be considered an alternative treatment option for ADHD children even if they have TLE. Additional studies are needed to confirm our results.     

Selection,constraint, and the evolution of coloration in African starlings

Colorful plumage plays a prominent role in the evolution of birds, influencing communication (sexual/social selection), and crypsis (natural selection). Comparative studies have focused primarily on these selective pressures, but the mechanisms underlying color production can also be important by constraining the color gamut upon which selection acts. Iridescence is particularly interesting to study the interaction between selection and color‐producing mechanisms because a broad range of colors can be produced with a shared template, and innovations to this template further expand this by increasing the parameters interacting to produce colors. We examine the patterns of ornamentation and dichromatism evolution in African starlings, a group remarkably diverse in color production mechanisms, social systems, and ecologies. We find that the presence of iridescence is ancestral to the group, being predominantly lost in females and cooperative breeders, as well as species with less labile templates. Color‐producing mechanisms interact and are the main predictors of plumage ornamentation and elaboration, with little influence of selective pressures in their evolution. Dichromatism, however is influenced by social system and the loss of iridescence. Our results show the importance of considering both selection and constraints, and the different roles that they may have, in the evolution of ornamentation and dimorphism.     

Solid-phase synthesis of a combinatorial library of dihydroceramide analogues and its activity in human alveolar epithelial cells

Solid-phase synthesis of a small combinatorial library of dihydroceramide analogues as mixtures of erythro and threo diastereomers is described. Some dihydroceramide analogues cause growth arrest and apoptosis in a dose-dependent manner in human alveolar epithelial cells. This activity is likely due to the threo isomers, as evidenced by cellular studies with a pair of diastereomerically pure N-acyldihydrosphingosines. The apoptotic activity reported in this work provides information for the design of new compounds that may provide the basis for the generation of biochemical tools for the study of different pathologies where ceramide and/or dihydroceramide are involved.     

Asymmetric CLASP-dependent nucleation of noncentrosomal microtubules at the trans-Golgi network

Proper organization of microtubule arrays is essential for intracellular trafficking and cell motility. It is generally assumed that most if not all microtubules in vertebrate somatic cells are formed by the centrosome. Here we demonstrate that a large number of microtubules in untreated human cells originate from the Golgi apparatus in a centrosome-independent manner. Both centrosomal and Golgi-emanating microtubules need gamma-tubulin for nucleation. Additionally, formation of microtubules at the Golgi requires CLASPs, microtubule-binding proteins that selectively coat noncentrosomal microtubule seeds. We show that CLASPs are recruited to the trans-Golgi network (TGN) at the Golgi periphery by the TGN protein GCC185. In sharp contrast to radial centrosomal arrays, microtubules nucleated at the peripheral Golgi compartment are preferentially oriented toward the leading edge in motile cells. We propose that Golgi-emanating microtubules contribute to the asymmetric microtubule networks in polarized cells and support diverse processes including post-Golgi transport to the cell front.     

Y chromosome microdeletions in Brazilian fertility clinic patients

Microdeletions in Yq are associated with defects in spermatogenesis, while those in the AZF region are considered critical for germ cell development. We examined microdeletions in the Y chromosomes of patients attended at the Laboratory of Human Reproduction of the Clinical Hospital of the Federal University of Goiás as part of a screening of patients who plan to undergo assisted reproduction. Analysis was made of the AZF region of the Y chromosome in men who had altered spermograms to detect possible microdeletions in Yq. Twenty-three patients with azoospermia and 40 with severe oligozoospermia were analyzed by PCR for the detection of six sequence-tagged sites: sY84 and sY86 for AZFa, sY127 and sY134 for AZFb, and sY254 and sY255 for AZFc. Microdeletions were detected in 28 patients, including 10 azoospermics and 18 severe oligozoospermics. The patients with azoospermia had 43.4% of their microdeletions in the AZFa region, 8.6% in the AZFb region and 17.4% in the AZFc region. In the severe oligozoospermics, 40% were in the AZFa region, 5% in the AZFb region and 5% in the AZFc region. We conclude that microdeletions can be the cause of idiopathic male infertility, supporting conclusions from previous studies.     

Conceptions of meiosis: misunderstandings among university students and errors

We have designed and tested an exercise to detect misconceptions among students about meiosis, a fundamental concept in genetics. A total of 30 students responded to a questionnaire, all of whom were in the fifth semester of the Biology bachelor’s degree program offered by the Faculty of Science of the National Autonomous University of Mexico. Our analysis showed that students have a poor understanding of the fundamental processes of meiosis and that they have trouble distinguishing them. When asked to diagram part of the process, none were able to produce a complete and accurate representation.     

A mechanistic view of enzyme inhibition and peptide hydrolysis in the active site of the SARS-CoV 3C-like peptidase

The 3C-like main peptidase 3CL(pro) is a viral polyprotein processing enzyme essential for the viability of the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV). While it is generalized that 3CL(pro) and the structurally related 3C(pro) viral peptidases cleave their substrates via a mechanism similar to that underlying the peptide hydrolysis by chymotrypsin-like serine proteinases (CLSPs), some of the hypothesized key intermediates have not been structurally characterized. Here, we present three crystal structures of SARS 3CL(pro) in complex with each of two members of a new class of peptide-based phthalhydrazide inhibitors. Both inhibitors form an unusual thiiranium ring with the nucleophilic sulfur atom of Cys145, trapping the enzyme's catalytic residues in configurations similar to the intermediate states proposed to exist during the hydrolysis of native substrates. Most significantly, our crystallographic data are consistent with a scenario in which a water molecule, possibly via indirect coordination from the carbonyl oxygen of Thr26, has initiated nucleophilic attack on the enzyme-bound inhibitor. Our data suggest that this structure resembles that of the proposed tetrahedral intermediate during the deacylation step of normal peptidyl cleavage.