Neural correlates of peer evaluation in irritable adolescents: Linking anticipation to receipt of social feedback

Elevated irritability during adolescence predicts mental health issues in adulthood. Social interactions commonly elicit symptoms of irritability. Prior research has traditionally examined neural activity during the anticipation of, and immediate reaction to, social feedback separately in irritable adolescents. However, studies suggest that irritable adolescents demonstrate altered brain activation when anticipating feedback, and these alterations may have downstream effects on the neural activity when actually presented with feedback. Thus, the goal of this study was to characterize the influence of irritability on the relationship between brain function during anticipation and receipt of social feedback. We leveraged the Virtual School task to mimic social interactions using dynamic stimuli. Parallel region of interest (ROI) analyses tested effects of anticipatory bilateral amygdala (or dorsal anterior cingulate cortex; dACC) activation on the dACC (or bilateral amygdala) activation during receipt of peer feedback. Parallel exploratory whole-brain analyses were conducted to identify the effects of anticipatory bilateral amygdala or dACC activation on other regions during receipt of peer feedback. In ROI analyses, more vs. less irritable adolescents showed distinct relationships between anticipatory bilateral amygdala activation and dACC activation when receiving predictably mean feedback. Across both whole-brain analyses, anticipatory bilateral amygdala and dACC activation were separately associated with activation in socioemotional regions of the brain during subsequent feedback. These relationships were modulated by irritability, and the valence and predictability of the feedback. This suggests that irritable adolescents may engage in altered emotion processing and regulation strategies, depending on the valence and predictability of social feedback.

A novel sugar beet cyst nematode effector 2D01 targets the Arabidopsis HAESA receptor-like kinase

Plant-parasitic cyst nematodes use a stylet to deliver effector proteins produced in oesophageal gland cells into root cells to cause disease in plants. These effectors are deployed to modulate plant defence responses and developmental programmes for the formation of a specialized feeding site called a syncytium. The Hg2D01 effector gene, coding for a novel 185-amino-acid secreted protein, was previously shown to be up-regulated in the dorsal gland of parasitic juveniles of the soybean cyst nematode Heterodera glycines, but its function has remained unknown. Genome analyses revealed that Hg2D01 belongs to a highly diversified effector gene family in the genomes of H. glycines and the sugar beet cyst nematode Heterodera schachtii. For functional studies using the model Arabidopsis thaliana-H. schachtii pathosystem, we cloned the orthologous Hs2D01 sequence from H. schachtii. We demonstrate that Hs2D01 is a cytoplasmic effector that interacts with the intracellular kinase domain of HAESA (HAE), a cell surface-associated leucine-rich repeat (LRR) receptor-like kinase (RLK) involved in signalling the activation of cell wall-remodelling enzymes important for cell separation during abscission and lateral root emergence. Furthermore, we show that AtHAE is expressed in the syncytium and, therefore, could serve as a viable host target for Hs2D01. Infective juveniles effectively penetrated the roots of HAE and HAESA-LIKE2 (HSL2) double mutant plants; however, fewer nematodes developed on the roots, consistent with a role for this receptor family in nematode infection. Taken together, our results suggest that the Hs2D01-AtHAE interaction may play an important role in sugar beet cyst nematode parasitism.

Hypermorphic SERK1 Mutations Function via a SOBIR1 Pathway to Activate Floral Abscission Signaling

In Arabidopsis (Arabidopsis thaliana), the abscission of floral organs is regulated by two related receptor-like protein kinases, HAESA (HAE) and HAESA-LIKE2 (HSL2). In complex with members of the SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) family of coreceptor protein kinases, HAE and HSL2 are activated when bound by INFLORESCENCE DEFICIENT IN ABSICSSION, a proteolytically processed peptide ligand, activating the expression of genes encoding secreted cell wall remodeling and hydrolase enzymes. hae hsl2 mutants fail to induce expression of these genes and retain floral organs indefinitely. Here, we report identification of an allelic series of hae hsl2 suppressor mutations in the SERK1 coreceptor protein kinase gene. Genetic and transcriptomic evidence indicates that these alleles represent a novel class of gain-of-function mutations that activate signaling independently of HAE/HSL2. We show that, surprisingly, the suppression effect does not rely on the protein kinase activity of SERK1 and that activation of signaling relies on the receptor-like kinase gene SUPPRESSOR OF BIR1 (SOBIR1). The effect of these mutations can be mimicked by loss of function of BAK1-INTERACTING RECEPTOR-LIKE KINASE1 (BIR1), a known negative regulator of SERK-SOBIR1 signaling. These results suggest that BIR1 negatively regulates SERK-SOBIR1 signaling during abscission and that the identified SERK1 mutations likely interfere with this negative regulation.

Transcriptomic evidence for distinct mechanisms underlying abscission deficiency in the Arabidopsis mutants haesa/haesa-like 2 and nevershed

Objective

In Arabidopsis, the abscission of floral organs is regulated by two related receptor-like protein kinases, HAESA and HAESA–like 2 (HAE/HSL2). Signaling by HAE/HSL2 leads to expression of genes encoding secreted cell wall remodeling and hydrolase enzymes. hae hsl2 mutants fail to induce expression of these genes and retain floral organs indefinitely. Mutants in the gene NEVERSHED (NEV) also fail to abscise floral organs and phenotypically resemble hae hsl2. NEV encodes an ADP-ribosylation factor GTPase-activating protein that localizes to the trans-Golgi network and early endosome. nev displays altered Golgi morphology and aberrations in vesicular trafficking. The mechanism by which nev fails to abscise is presently unknown. It has been hypothesized that nev fails to activate HAE/HSL2 signaling. In this study we use RNA-Sequencing to test this hypothesis.

Results

We show that the transcriptional alterations in hae hsl2 and nev are highly divergent. hae hsl2 displays a clear reduction in expression of genes associated with cell wall remodeling and pectin degradation, while nev displays vast transcriptional changes associated with response to pathogens. These results suggest that the mechanism of the defect between hae hsl2 and nev are distinct.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3864-x) contains supplementary material, which is available to authorized users.

Human Skeletal Stem Cell Response to Multiscale Topography Induced by Large Area Electron Beam Irradiation Surface Treatment

The healthcare socio-economic environment is irreversibly changing as a consequence of an increasing aging population, consequent functional impairment, and patient quality of life expectations. The increasing complexity of ensuing clinical scenarios compels a critical search for novel musculoskeletal regenerative and replacement strategies. While joint arthroplasty is a highly effective treatment for arthritis and osteoporosis, further innovation and refinement of uncemented implants are essential in order to improve implant integration and reduce implant revision rate. This is critical given financial restraints and the drive to improve cost-effectiveness and quality of life outcomes. Multi-scale modulation of implant surfaces, offers an innovative approach to enhancement in implant performance. In the current study, we have examined the potential of large area electron beam melting to alter the surface nanotopography in titanium alloy (Ti6Al4V). We evaluated the in vitro osteogenic response of human skeletal stem cells to the resultant nanotopography, providing evidence of the relationship between the biological response, particularly Collagen type I and Osteocalcin gene activation, and surface nanoroughness. The current studies demonstrate osteogenic gene induction and morphological cell changes to be significantly enhanced on a topography Ra of ~40 nm with clinical implications therein for implant surface treatment and generation.

Advances in abscission signaling

Abscission is a process in plants for shedding unwanted organs such as leaves, flowers, fruits, or floral organs. Shedding of leaves in the fall is the most visually obvious display of abscission in nature. The very shape plants take is forged by the processes of growth and abscission. Mankind manipulates abscission in modern agriculture to do things such as prevent pre-harvest fruit drop prior to mechanical harvesting in orchards. Abscission occurs specifically at abscission zones that are laid down as the organ that will one day abscise is developed. A sophisticated signaling network initiates abscission when it is time to shed the unwanted organ. In this article, we review recent advances in understanding the signaling mechanisms that activate abscission. Physiological advances and roles for hormones in abscission are also addressed. Finally, we discuss current avenues for basic abscission research and potentially lucrative future directions for its application to modern agriculture.

Leaf shedding as an anti-bacterial defense in Arabidopsis cauline leaves

Plants utilize an innate immune system to protect themselves from disease. While many molecular components of plant innate immunity resemble the innate immunity of animals, plants also have evolved a number of truly unique defense mechanisms, particularly at the physiological level. Plant's flexible developmental program allows them the unique ability to simply produce new organs as needed, affording them the ability to replace damaged organs. Here we develop a system to study pathogen-triggered leaf abscission in Arabidopsis. Cauline leaves infected with the bacterial pathogen Pseudomonas syringae abscise as part of the defense mechanism. Pseudomonas syringae lacking a functional type III secretion system fail to elicit an abscission response, suggesting that the abscission response is a novel form of immunity triggered by effectors. HAESA/HAESA-like 2, INFLORESCENCE DEFICIENT IN ABSCISSION, and NEVERSHED are all required for pathogen-triggered abscission to occur. Additionally phytoalexin deficient 4, enhanced disease susceptibility 1, salicylic acid induction-deficient 2, and senescence-associated gene 101 plants with mutations in genes necessary for bacterial defense and salicylic acid signaling, and NahG transgenic plants with low levels of salicylic acid fail to abscise cauline leaves normally. Bacteria that physically contact abscission zones trigger a strong abscission response; however, long-distance signals are also sent from distal infected tissue to the abscission zone, alerting the abscission zone of looming danger. We propose a threshold model regulating cauline leaf defense where minor infections are handled by limiting bacterial growth, but when an infection is deemed out of control, cauline leaves are shed. Together with previous results, our findings suggest that salicylic acid may regulate both pathogen- and drought-triggered leaf abscission.

Disrupting ER-associated protein degradation suppresses the abscission defect of a weak hae hsl2 mutant in Arabidopsis

In Arabidopsis thaliana, the process of abscission, or the shedding of unwanted organs, is mediated by two genes, HAESA (HAE) and HAESA-LIKE 2 (HSL2), encoding receptor-like protein kinases (RLKs). The double loss-of-function mutant hae-3 hsl2-3 is completely deficient in floral abscission, but, interestingly, the hae-3 hsl2-9 mutant displays a less severe defect. This mutant was chosen for an ethyl methanesulfonate (EMS) screen to isolate enhancer and suppressor mutants, and two such suppressors are the focus of this study. Pooled DNA from the F₂ generation of a parental backcross was analyzed by genome sequencing to reveal candidate genes, two of which complement the suppressor phenotype. These genes, EMS-MUTAGENIZED BRI1 SUPPRESSOR 3 (EBS3) and EBS4, both encode mannosyltransferases involved in endoplasmic reticulum (ER)-associated degradation (ERAD) of proteins. Further analysis of these suppressor lines revealed that suppressor mutations are acting solely on the partially functional hsl2-9 mutant receptor to modify the abscission phenotype. Expressing a hsl2-9-yellow fluorescent protein (YFP) transgene in ebs3 mutants yields a higher fluorescent signal than in EBS3/ebs3, suggesting that these mutants restore abscission by disrupting ERAD to allow accumulation of the hsl2-9 receptor, which probably escapes degradation to be trafficked to the plasma membrane to regain signaling.

Core Mechanisms Regulating Developmentally Timed and Environmentally Triggered Abscission

Drought-triggered abscission is a strategy used by plants to avoid the full consequences of drought; however, it is poorly understood at the molecular genetic level. Here, we show that Arabidopsis (Arabidopsis thaliana) can be used to elucidate the pathway controlling drought-triggered leaf shedding. We further show that much of the pathway regulating developmentally timed floral organ abscission is conserved in regulating drought-triggered leaf abscission. Gene expression of HAESA (HAE) and INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) is induced in cauline leaf abscission zones when the leaves become wilted in response to limited water and HAE continues to accumulate in the leaf abscission zones through the abscission process. The genes that encode HAE/HAESA-LIKE2, IDA, NEVERSHED, and MAPK KINASE4 and 5 are all necessary for drought-induced leaf abscission. Our findings offer a molecular mechanism explaining drought-triggered leaf abscission. Furthermore, the ability to study leaf abscission in Arabidopsis opens up a new avenue to tease apart mechanisms involved in abscission that have been difficult to separate from flower development as well as for understanding the mechanistic role of water and turgor pressure in abscission.

Serine 231 and 257 of Agamous-like 15 are phosphorylated in floral receptacles

The large dynamic range of gene expression changes accompanying floral organ abscission can be explained by a molecular positive feedback loop that regulates the process. In short, a mitogen-activated protein kinase (MAPK) cascade, positioned genetically downstream from the abscission receptor HAESA (HAE), phosphorylates the transcription factor, AGAMOUS-like 15 (AGL15), allowing HAE to be expressed. However, it is unknown which residues of AGL15 are phosphorylated and precisely how phosphorylation alters AGL15 function. Here we report that serine 231 and 257 of AGL15 are phosphorylated in floral receptacles. Effects of phosphorylation on AGL15 are discussed.

Analysis of Phosphorylation of the Receptor-Like Protein Kinase HAESA during Arabidopsis Floral Abscission

Receptor-like protein kinases (RLKs) are the largest family of plant transmembrane signaling proteins. Here we present functional analysis of HAESA, an RLK that regulates floral organ abscission in Arabidopsis. Through in vitro and in vivo analysis of HAE phosphorylation, we provide evidence that a conserved phosphorylation site on a region of the HAE protein kinase domain known as the activation segment positively regulates HAE activity. Additional analysis has identified another putative activation segment phosphorylation site common to multiple RLKs that potentially modulates HAE activity. Comparative analysis suggests that phosphorylation of this second activation segment residue is an RLK specific adaptation that may regulate protein kinase activity and substrate specificity. A growing number of RLKs have been shown to exhibit biologically relevant dual specificity toward serine/threonine and tyrosine residues, but the mechanisms underlying dual specificity of RLKs are not well understood. We show that a phospho-mimetic mutant of both HAE activation segment residues exhibits enhanced tyrosine auto-phosphorylation in vitro, indicating phosphorylation of this residue may contribute to dual specificity of HAE. These results add to an emerging framework for understanding the mechanisms and evolution of regulation of RLK activity and substrate specificity.

From Gigabyte to Kilobyte: A Bioinformatics Protocol for Mining Large RNA-Seq Transcriptomics Data

RNA-Seq techniques generate hundreds of millions of short RNA reads using next-generation sequencing (NGS). These RNA reads can be mapped to reference genomes to investigate changes of gene expression but improved procedures for mining large RNA-Seq datasets to extract valuable biological knowledge are needed. RNAMiner--a multi-level bioinformatics protocol and pipeline--has been developed for such datasets. It includes five steps: Mapping RNA-Seq reads to a reference genome, calculating gene expression values, identifying differentially expressed genes, predicting gene functions, and constructing gene regulatory networks. To demonstrate its utility, we applied RNAMiner to datasets generated from Human, Mouse, Arabidopsis thaliana, and Drosophila melanogaster cells, and successfully identified differentially expressed genes, clustered them into cohesive functional groups, and constructed novel gene regulatory networks. The RNAMiner web service is available at http://calla.rnet.missouri.edu/rnaminer/index.html.

Scalable high-mobility MoS2 thin films fabricated by an atmospheric pressure chemical vapor deposition process at ambient temperature

Nano-scale MoS2 thin films are successfully deposited on a variety of substrates by atmospheric pressure chemical vapor deposition (APCVD) at ambient temperature, followed by a two-step annealing process. These annealed MoS2 thin films are characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), micro-Raman, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-VIS-NIR spectrometry, photoluminescence (PL) and Hall Effect measurement. Key optical and electronic properties of APCVD grown MoS2 thin films are determined. This APCVD process is scalable and can be easily incorporated with conventional lithography as the deposition is taking place at room temperature. We also find that the substrate material plays a significant role in the crystalline structure formation during the annealing process and single crystalline MoS2 thin films can be achieved by using both c-plane ZnO and c-plane sapphire substrates. These APCVD grown nano-scale MoS2 thin films show great promise for nanoelectronic and optoelectronic applications.

Gasoline toxicology: overview of regulatory and product stewardship programs

Significant efforts have been made to characterize the toxicological properties of gasoline. There have been both mandatory and voluntary toxicology testing programs to generate hazard characterization data for gasoline, the refinery process streams used to blend gasoline, and individual chemical constituents found in gasoline. The Clean Air Act (CAA) (Clean Air Act, 2012: § 7401, et seq.) is the primary tool for the U.S. Environmental Protection Agency (EPA) to regulate gasoline and this supplement presents the results of the Section 211(b) Alternative Tier 2 studies required for CAA Fuel and Fuel Additive registration. Gasoline blending streams have also been evaluated by EPA under the voluntary High Production Volume (HPV) Challenge Program through which the petroleum industry provide data on over 80 refinery streams used in gasoline. Product stewardship efforts by companies and associations such as the American Petroleum Institute (API), Conservation of Clean Air and Water Europe (CONCAWE), and the Petroleum Product Stewardship Council (PPSC) have contributed a significant amount of hazard characterization data on gasoline and related substances. The hazard of gasoline and anticipated exposure to gasoline vapor has been well characterized for risk assessment purposes.

Letting go is never easy: abscission and receptor-like protein kinases

Abscission is the process by which plants discard organs in response to environmental cues/stressors, or as part of their normal development. Abscission has been studied throughout the history of the plant sciences and in numerous species. Although long studied at the anatomical and physiological levels, abscission has only been elucidated at the molecular and genetic levels within the last two decades, primarily with the use of the model plant Arabidopsis thaliana. This has led to the discovery of numerous genes involved at all steps of abscission, including key pathways involving receptor-like protein kinases (RLKs). This review covers the current knowledge of abscission research, highlighting the role of RLKs. [Figure: see text] John C. Walker (Corresponding author).

A simple in vitro method to measure autophosphorylation of protein kinases

Receptor-like protein kinases (RLKs) are a large and important group of plant proteins involved in numerous aspects of development and stress response. Within this family, homo-oligermization of receptors followed by autophosphorylation of the intracellular protein kinase domain appears to be a widespread mechanism to regulate protein kinase activity. In vitro studies of several RLKs have identified autophosphorylation sites involved in regulation of catalytic activity and signaling in vivo. Recent work has established that multiple RLKs are biochemically active when expressed in E. coli and readily autophosphorylate prior to purification or subsequent manipulation. This observation has led us to develop a simplified method for assaying RLK phosphorylation status as an indirect measure of intrinsic autophosphorylation activity. The method involves expressing a recombinant RLK protein kinase domain in E. coli, followed by SDS-PAGE of boiled cell lysate, and sequential staining with the phosphoprotein stain Pro-Q Diamond and a colloidal Coomassie total protein stain. We show this method can be used to measure and quantify in vitro autophosphorylation levels of recombinant wildtype and mutant versions of the Arabidopsis RLK HAESA, as well as to detect transphosphorylation activity of recombinant HAESA against a protein kinase inactive version of itself. Our method has several advantages over traditional protein kinase assays. It does not require protein purification, transfer, blotting, or radioactive reagents. It allows for rapid and quantitative assessment of autophosphorylation levels and should have general utility in the study of any autophosphorylating protein kinase expressed in E. coli.

Transcriptional profiling of the Arabidopsis abscission mutant hae hsl2 by RNA-Seq

BACKGROUND

Abscission is a mechanism by which plants shed entire organs in response to both developmental and environmental signals. Arabidopsis thaliana, in which only the floral organs abscise, has been used extensively to study the genetic, molecular and cellular processes controlling abscission. Abscission in Arabidopsis requires two genes that encode functionally redundant receptor-like protein kinases, HAESA (HAE) and HAESA-LIKE 2 (HSL2). Double hae hsl2 mutant plants fail to abscise their floral organs at any stage of floral development and maturation.

RESULTS

Using RNA-Seq, we compare the transcriptomes of wild-type and hae hsl2 stage 15 flowers, using the floral receptacle which is enriched for abscission zone cells. 2034 genes were differentially expressed with a False Discovery Rate adjusted p < 0.05, of which 349 had two fold or greater change in expression. Differentially expressed genes were enriched for hydrolytic, cell wall modifying, and defense related genes. Testing several of the differentially expressed genes in INFLORESCENCE DEFICIENT IN ABSCISSION (ida) mutants shows that many of the same genes are co-regulated by IDA and HAE HSL2 and support the role of IDA in the HAE and HSL2 signaling pathway. Comparison to microarray data from stamen abscission zones show distinct patterns of expression of genes that are dependent on HAE HSL2 and reveal HAE HSL2- independent pathways.

CONCLUSION

HAE HSL2-dependent and HAE HSL2-independent changes in genes expression are required for abscission. HAE and HSL2 affect the expression of cell wall modifying and defense related genes necessary for abscission. The HAE HSL2-independent genes also appear to have roles in abscission and additionally are involved in processes such as hormonal signaling, senescence and callose deposition.

A MAPK cascade downstream of ERECTA receptor-like protein kinase regulates Arabidopsis inflorescence architecture by promoting localized cell proliferation

Spatiotemporal-specific cell proliferation and cell differentiation are critical to the formation of normal tissues, organs, and organisms. The highly coordinated cell differentiation and proliferation events illustrate the importance of cell-cell communication during growth and development. In Arabidopsis thaliana, ERECTA (ER), a receptor-like protein kinase, plays important roles in promoting localized cell proliferation, which determines inflorescence architecture, organ shape, and size. However, the downstream signaling components remain unidentified. Here, we report a mitogen-activated protein kinase (MAPK; or MPK) cascade that functions downstream of ER in regulating localized cell proliferation. Similar to an er mutant, loss of function of MPK3/MPK6 or their upstream MAPK kinases (MAPKKs; or MKKs), MKK4/MKK5, resulted in shortened pedicels and clustered inflorescences. Epistasis analysis demonstrated that the gain of function of MKK4 and MKK5 transgenes could rescue the loss-of-function er mutant phenotype at both morphological and cellular levels, suggesting that the MPK3/MPK6 cascade functions downstream of the ER receptor. Furthermore, YODA (YDA), a MAPKK kinase, was shown to be upstream of MKK4/MKK5 and downstream of ER in regulating inflorescence architecture based on both gain- and loss-of-function data. Taken together, these results suggest that the YDA-MKK4/MKK5-MPK3/MPK6 cascade functions downstream of the ER receptor in regulating localized cell proliferation, which further shapes the morphology of plant organs.

DVL genes play a role in the coordination of socket cell recruitment and differentiation

Specialized plant cells arise from undifferentiated cells through a series of developmental steps. The decision to enter into a certain differentiation pathway depends in many cases on signals from neighbouring cells. The ability of cells to engage in short-range intercellular communication permits the coordination of cell actions necessary in many developmental processes. Overexpression of genes from the DEVIL/ROTUNDIFOLIA (DVL/ROT) family results in severe developmental alterations, but very little is known about their mechanism of action. This work presents evidence that suggests a role for these genes in local signalling, specifically in the coordination of socket cell recruitment and differentiation. Overexpression of different DVL genes results in protuberances at the base of the trichomes surrounded by several rows of elongated epidermal cells, morphologically similar to socket cells. Localized overexpression of DVL4 in trichomes and socket cells during early developmental stages activates expression of socket cell markers in additional cells, farther away from the trichome. The same phenomenon is observed in an activation tagged line of DVL1, which also shows an increase in the number of socket cells in contact with the trichome. The roles of individual DVL genes have been difficult to discover since their overexpression phenotypes are quite similar. In gl1 leaves that lack trichomes and socket cells DVL1 expression shows a 69% reduction, suggesting that this gene could be involved in the coordination of socket cell development in wild-type plants.

Depression in Down syndrome: a review of the literature

BACKGROUND

Depression has been frequently reported in individuals with Down Syndrome (DS). The aim of this article is to provide a comprehensive, critical review of the clinically relevant literature concerning depression in DS, with a focus on epidemiology, potential risk factors, diagnosis, course characteristics and treatment.

METHODS

We searched the PUBMED database (January 2011) using the keywords ("Depressive Disorder [MESH]" OR "Depression [MESH]" OR "depress* [All Fields]") AND ("Down Syndrome [MESH]" OR "Down syndrome [All Fields]" OR "Down's syndrome [All Fields]"). Review articles not adding new information, single case reports and papers focusing on subjects other than depression in DS were excluded.

RESULTS

The PUBMED search resulted in 390 articles, of which 30 articles were finally included. Recent information does not support earlier suggestions of an increased prevalence of depression in DS compared to other causes of Intellectual Disability (ID). However, individuals with DS show many vulnerabilities and are exposed to high levels of stressors that could confer an increased risk for the development of depression. Apart from general risk factors, several potential risk factors are more specific for DS, including smaller hippocampal volumes, certain changes in neurotransmitter systems, deficits in language and working memory, attachment behaviours and frequently occurring somatic disorders. Protective factors might play a role in reducing the vulnerability to depression. The diagnosis of depression in DS is mainly based upon observable characteristics, and therefore, the use of modified diagnostic criteria is advised. Although several common treatments, including antidepressants, electroconvulsive therapy and psychotherapy seem effective, there is evidence of undertreatment of depression in DS.

CONCLUSIONS

There are important limitations to our current clinical knowledge of depression in DS. Future studies should include systematic evaluations of pharmacotherapeutic and psychotherapeutic interventions.

Development of lymphocyte subpopulations in preterm infants

In preterm neonates the immune system is thought to be less developed at birth, but very little is known about the actual size of lymphocyte subpopulations, and even less about the maturation of these subpopulations during the first months after a premature birth. To evaluate the development of lymphocyte subpopulations in preterm infants during the first 3 months after birth, we performed a prospective longitudinal study in two hospitals in the Netherlands. Preterm neonates (n = 38) of all post-menstrual ages were included and blood samples were taken from cord blood, and at 1 week, 6 weeks, and 3 months. Lymphocyte subpopulations were measured by four-colour flow cytometry. The data were compared with follow-up data obtained in healthy term neonates (n = 8), and with single samples from school age children (n = 5) and adults (n = 5). Overall, we found a similar pattern of post-natal development of lymphocyte subpopulations in the term and preterm infants. Both B lymphocytes and helper and cytotoxic T lymphocytes mainly consist of naive cells at birth and during the 3 months of follow-up in all neonatal age groups. So, the preterm immune system seems to be able to generate an outburst of naive T and B lymphocytes from the thymus and bone marrow within the same time span after the start of post-natal antigenic stimulation from the environment as the term immune system, but, with lower post-menstrual age, the absolute counts of naive helper T lymphocytes are lower.

Periodization: current review and suggested implementation for athletic rehabilitation

BACKGROUND

Clinicians are constantly faced with the challenge of designing training programs for injured and noninjured athletes that maximize healing and optimize performance. Periodization is a concept of systematic progression-that is, resistance training programs that follow predictable patterns of change in training variables. The strength training literature is abundant with studies comparing periodization schemes on uninjured, trained, and untrained athletes. The rehabilitation literature, however, is scarce with information about how to optimally design resistance training programs based on periodization principles for injured athletes. The purpose of this review is to discuss relevant training variables and methods of periodization, as well as periodization program outcomes. A secondary purpose is to provide an anecdotal framework regarding implementation of periodization principles into rehabilitation programs.

EVIDENCE ACQUISITION

A Medline search from 1979 to 2009 was implemented with the keywords periodization, strength training, rehabilitation, endurance, power, hypertrophy, and resistance training with the Boolean term AND in all possible combinations in the English language. Each author also undertook independent hand searching of article references used in this review.

RESULTS

Based on the studies researched, periodized strength training regimens demonstrate improved outcomes as compared to nonperiodized programs.

CONCLUSIONS

Despite the evidence in the strength training literature supporting periodization programs, there is a considerable lack of data in the rehabilitation literature about program design and successful implementation of periodization into rehabilitation programs.

Isolation of cloned cDNAs to auxin-responsive poly(A)RNAs of elongating soybean hypocotyl

Auxin-responsive cDNA clones have been isolated from a cDNA library prepared from elongating soybean hypocotyl poly(A)(+)RNA. The expression of two such sequences has been assessed by RNA blot hybridization analyses during normal developmental transitions in the soybean hypocotyl and during incubation of sections excised from the region of cell elongation. The concentrations of these poly(A)(+)RNAs are higher in the elongating zone than in the apical and mature zones of the hypocotyl. Both poly(A)(+)RNAs are depleted during incubation of the sections in the absence of auxin. The loss of one of these sequences (pJCW1) is prevented by the addition of auxin to the incubation medium while the other sequence (pJCW2) increases above the initial level in the presence of auxin. The addition of auxin to auxin-depleted tissue in which the sequences are depleted results in rapid accumulation of these poly(A)(+)RNAs; pJCW1 accumulates to the control level while pJCW2 increases well above the control level. These data along with others [Baulcombe, D. C. & Key, J. L. (1980) J. Biol. Chem. 255, 8907-8913] demonstrate directly a highly selective effect of auxin on the expression of a small number of mRNAs in tissues undergoing both cell elongation and cell division in response to auxin. Although the data are suggestive of a close association betwen auxin action and altered gene expression, a causal relationship is not established. It seems highly unlikely, however, that such specific effects of auxin on gene expression are unimportant in auxin physiology.

DNA sequences required for anaerobic expression of the maize alcohol dehydrogenase 1 gene

Expression of the maize alcohol dehydrogenase 1 (Adh1) gene is transcriptionally regulated under conditions of anaerobic stress. DNA sequences required for the expression of Adh1 have been identified by a functional analysis of in vitro constructed hybrid genes consisting of the Adh1 promoter fused to the chloramphenicol acetyltransferase coding region. A series of 5' deletions, 3' deletions, hybrid promoters, and linker scanning mutants of the Adh-CAT hybrid gene were introduced into maize protoplasts by electroporation and assayed for chloramphenicol acetyltransferase activity after incubation of the protoplasts under different oxygen tensions. The results indicate that a 40-base-pair DNA sequence within the Adh1 promoter is required for anaerobically regulated expression of the hybrid gene. Clustered point mutations in this sequence show that it is composed of two essential regions, each approximately 15 base pairs, separated by a 10-base-pair DNA sequence that does not appear to be important for anaerobic expression. Attachment of this 40-base-pair element to an unrelated promoter shows that this DNA sequence is both necessary and sufficient for induction of gene expression by low oxygen stress.

Bioinformatic identification of plant peptides

Plant peptides play a number of important roles in defence, development and many other aspects of plant physiology. Identifying additional peptide sequences provides the starting point to investigate their function using molecular, genetic or biochemical techniques. Due to their small size, identifying peptide sequences may not succeed using the default bioinformatic approaches that work well for average-sized proteins. There are two general scenarios related to bioinformatic identification of peptides to be discussed in this paper. In the first scenario, one already has the sequence of a plant peptide and is trying to find more plant peptides with some sequence similarity to the starting peptide. To do this, the Basic Local Alignment Search Tool (BLAST) is employed, with the parameters adjusted to be more favourable for identifying potential peptide matches. A second scenario involves trying to identify plant peptides without using sequence similarity searches to known plant peptides. In this approach, features such as protein size and the presence of a cleavable amino-terminal signal peptide are used to screen annotated proteins. A variation of this method can be used to screen for unannotated peptides from genomic sequences. Bioinformatic resources related to Arabidopsis thaliana will be used to illustrate these approaches.

Genetic interactions between the miRNA164-CUC2 regulatory module and BREVIPEDICELLUS in Arabidopsis developmental patterning

The proper regulation of enlargement and patterning of plant lateral organs is essential for plant functionality. In an earlier work, we characterized the role of a microRNA (miRNA)-transcription factor regulatory module, miRNA164-CUC2, in the enlargement and patterning of multiple lateral organs in Arabidopsis. This regulatory module genetically interacts with another transcription factor, CRC, in fruit development patterning. Here, we characterize the genetic interaction of this module with a homeodomain transcription factor, BREVIPEDICELLUS (BP), that has been shown to play roles in leaf development patterning.

A microRNA-transcription factor module regulates lateral organ size and patterning in Arabidopsis

Precise regulatory mechanisms are necessary to properly control the enlargement and patterning of plant lateral organs. However, our understanding of the regulatory modules that govern both of these processes is limited. An emerging theme in plant development is microRNA (miRNA)-mediated gene regulation of transcription factors, including several NAC domain family members such as CUP-SHAPED COTYLEDON2 (CUC2). We uncovered a novel allele of CUC2, cuc2-1D, that revealed important functions of miRNAs and CUC2 in a regulatory module governing lateral organ enlargement and patterning. cuc2-1D carried a single point mutation in the CUC2 miRNA target site, disrupting miRNA targeting. Disruption of the tight balance between CUC2 and its targeting miRNA, miRNA164, led to over-accumulation of CUC2 mRNA and expansion of the CUC2 expression domain. cuc2-1D plants had enlarged vegetative and reproductive lateral organs relative to wild-type plants. Mechanistically, these enlarged organs resulted from an increase in cell proliferation that occurred over a longer developmental time frame relative to wild-type. This organ enlargement was dependent on the receptor-like kinase, ERECTA (ER). This and lateral organ patterning phenotypes in cuc2-1D suggest that miRNA164 and CUC2 are critical regulators of both processes. Therefore, we propose that miRNA164 and CUC2 form a central regulatory module that acts as a governor of lateral organ patterning and expansion.

A microRNA-transcription factor module regulates lateral organ size and patterning in Arabidopsis

Precise regulatory mechanisms are necessary to properly control the enlargement and patterning of plant lateral organs. However, our understanding of the regulatory modules that govern both of these processes is limited. An emerging theme in plant development is microRNA (miRNA)-mediated gene regulation of transcription factors, including several NAC domain family members such as CUP-SHAPED COTYLEDON2 (CUC2). We uncovered a novel allele of CUC2, cuc2-1D, that revealed important functions of miRNAs and CUC2 in a regulatory module governing lateral organ enlargement and patterning. cuc2-1D carried a single point mutation in the CUC2 miRNA target site, disrupting miRNA targeting. Disruption of the tight balance between CUC2 and its targeting miRNA, miRNA164, led to over-accumulation of CUC2 mRNA and expansion of the CUC2 expression domain. cuc2-1D plants had enlarged vegetative and reproductive lateral organs relative to wild-type plants. Mechanistically, these enlarged organs resulted from an increase in cell proliferation that occurred over a longer developmental time frame relative to wild-type. This organ enlargement was dependent on the receptor-like kinase, ERECTA (ER). This and lateral organ patterning phenotypes in cuc2-1D suggest that miRNA164 and CUC2 are critical regulators of both processes. Therefore, we propose that miRNA164 and CUC2 form a central regulatory module that acts as a governor of lateral organ patterning and expansion.

14-3-3 and FHA domains mediate phosphoprotein interactions

Many aspects of plant growth and development require specific protein interactions to carry out biochemical and cellular functions. Several proteins mediate these interactions, two of which specifically recognize phosphoproteins: 14-3-3 proteins and proteins with FHA domains. These are the only phosphobinding domains identified in plants. Both domains are present in animals and plants, and are used by plant proteins to regulate metabolic, developmental, and signaling pathways. 14-3-3s regulate sugar metabolism, proton gradients, and control transcription factor localization. FHA domains are modular domains often found in multidomain proteins that are involved in signal transduction and plant development.

The FHA domain proteins DAWDLE in Arabidopsis and SNIP1 in humans act in small RNA biogenesis

Proteins containing the forkhead-associated domain (FHA) are known to act in biological processes such as DNA damage repair, protein degradation, and signal transduction. Here we report that DAWDLE (DDL), an FHA domain-containing protein in Arabidopsis, acts in the biogenesis of miRNAs and endogenous siRNAs. Unlike mutants of genes known to participate in the processing of miRNA precursors, such as dcl1, hyponastic leaves1, and serrate, ddl mutants show reduced levels of pri-miRNAs as well as mature miRNAs. Promoter activity of MIR genes, however, is not affected by ddl mutations. DDL is an RNA binding protein and is able to interact with DCL1. In addition, we found that SNIP1, the human homolog of DDL, is involved in miRNA biogenesis and interacts with Drosha. Therefore, we uncovered an evolutionarily conserved factor in miRNA biogenesis. We propose that DDL participates in miRNA biogenesis by facilitating DCL1 to access or recognize pri-miRNAs.

Haplo-insufficiency of MPK3 in MPK6 mutant background uncovers a novel function of these two MAPKs in Arabidopsis ovule development

The plant life cycle includes diploid sporophytic and haploid gametophytic generations. Female gametophytes (embryo sacs) in higher plants are embedded in specialized sporophytic structures (ovules). Here, we report that two closely related mitogen-activated protein kinases in Arabidopsis thaliana, MPK3 and MPK6, share a novel function in ovule development: in the MPK6 mutant background, MPK3 is haplo-insufficient, giving female sterility when heterozygous. By contrast, in the MPK3 mutant background, MPK6 does not show haplo-insufficiency. Using wounding treatment, we discovered gene dosage-dependent activation of MPK3 and MPK6. In addition, MPK6 activation is enhanced when MPK3 is null, which may help explain why mpk3(-/-) mpk6(+/-) plants are fertile. Genetic analysis revealed that the female sterility of mpk3(+/-) mpk6(-/-) plants is a sporophytic effect. In mpk3(+/-) mpk6(-/-) mutant plants, megasporogenesis and megagametogenesis are normal and the female gametophyte identity is correctly established. Further analysis demonstrates that the mpk3(+/-) mpk6(-/-) ovules have abnormal integument development with arrested cell divisions at later stages. The mutant integuments fail to accommodate the developing embryo sac, resulting in the embryo sacs being physically restricted and female reproductive failure. Our results highlight an essential function of MPK3 and MPK6 in promoting cell division in the integument specifically during ovule development.

Phosphoprotein and Phosphopeptide Interactions with the FHA Domain from Arabidopsis Kinase-Associated Protein Phosphatase

FHA domains are phosphoThr recognition modules found in diverse signaling proteins, including kinase-associated protein phosphatase (KAPP) from Arabidopsis thaliana. The kinase-interacting FHA domain (KI-FHA) of KAPP targets it to function as a negative regulator of some receptor-like kinase (RLK) signaling pathways important in plant development and environmental responses. To aid in the identification of potential binding sites for the KI-FHA domain, we predicted (i) the structure of a representative KAPP-binding RLK, CLAVATA1, and (ii) the functional surfaces of RLK kinase domains using evolutionary trace analysis. We selected phosphopeptides from KAPP-binding Arabidopsis RLKs for in vitro studies of association with KI-FHA from KAPP. Three phosphoThr peptide fragments from the kinase domain of CLV1 or BAK1 were found to bind KI-FHA with KD values of 8-20 microM, by NMR or titration calorimetry. Their affinity is driven by favorable enthalpy and solvation entropy gain. Mutagenesis of these three threonine sites suggests Thr546 in the C-lobe of the BAK1 kinase domain to be a principal but not sole site of KI-FHA binding in vitro. The brassinosteroid receptor BRI1 and KAPP are shown to associate in vivo and in vitro. Further genetic studies indicate that KAPP may be a negative regulator of the BRI1 signaling transduction pathway. 15N-Labeled KI-FHA was titrated with the GST-BRI1 kinase domain and monitored by NMR. BRI1 interacts with the same 3/4, 4/5, 6/7, 8/9, and 10/11 recognition loops of KI-FHA, with similar affinity as the phosphoThr peptides.

Stomatal development and patterning are regulated by environmentally responsive mitogen-activated protein kinases in Arabidopsis

Stomata are specialized epidermal structures that regulate gas (CO(2) and O(2)) and water vapor exchange between plants and their environment. In Arabidopsis thaliana, stomatal development is preceded by asymmetric cell divisions, and stomatal distribution follows the one-cell spacing rule, reflecting the coordination of cell fate specification. Stomatal development and patterning are regulated by both genetic and environmental signals. Here, we report that Arabidopsis MITOGEN-ACTIVATED PROTEIN KINASE3 (MPK3) and MPK6, two environmentally responsive mitogen-activated protein kinases (MAPKs), and their upstream MAPK kinases, MKK4 and MKK5, are key regulators of stomatal development and patterning. Loss of function of MKK4/MKK5 or MPK3/MPK6 disrupts the coordinated cell fate specification of stomata versus pavement cells, resulting in the formation of clustered stomata. Conversely, activation of MKK4/MKK5-MPK3/MPK6 causes the suppression of asymmetric cell divisions and stomatal cell fate specification, resulting in a lack of stomatal differentiation. We further establish that the MKK4/MKK5-MPK3/MPK6 module is downstream of YODA, a MAPKKK. The establishment of a complete MAPK signaling cascade as a key regulator of stomatal development and patterning advances our understanding of the regulatory mechanisms of intercellular signaling events that coordinate cell fate specification during stomatal development.

The Arabidopsis unannotated secreted peptide database, a resource for plant peptidomics

In the era of genomics, if a gene is not annotated, it is not investigated. Due to their small size, genes encoding peptides are often missed in genome annotations. Secreted peptides are important regulators of plant growth, development, and physiology. Identification of additional peptide signals by sequence homology searches has had limited success due to sequence heterogeneity. A bioinformatics approach was taken to find unannotated Arabidopsis (Arabidopsis thaliana) peptides. Arabidopsis chromosome sequences were searched for all open reading frames (ORFs) encoding peptides and small proteins between 25 and 250 amino acids in length. The translated ORFs were then sequentially queried for the presence of an amino-terminal cleavable signal peptide, the absence of transmembrane domains, and the absence of endoplasmic reticulum lumenal retention sequences. Next, the ORFs were filtered against the The Arabidopsis Information Resource 6.0 annotated Arabidopsis genes to remove those ORFs overlapping known genes. The remaining 33,809 ORFs were placed in a relational database to which additional annotation data were deposited. Genome-wide tiling array data were compared with the coordinates of the ORFs, supporting the possibility that many of the ORFs may be expressed. In addition, clustering and sequence similarity analyses revealed that many of the putative peptides are in gene families and/or appear to be present in the rice (Oryza sativa) genome. A subset of the ORFs was evaluated by reverse transcription-PCR and, for one-fifth of those, expression was detected. These results support the idea that the number and diversity of plant peptides is broader than currently assumed. The peptides identified and their annotation data may be viewed or downloaded through a searchable Web interface at peptidome.missouri.edu.

DAWDLE, a forkhead-associated domain gene, regulates multiple aspects of plant development

Phosphoprotein-binding domains are found in many different proteins and specify protein-protein interactions critical for signal transduction pathways. Forkhead-associated (FHA) domains bind phosphothreonine and control many aspects of cell proliferation in yeast (Saccharomyces cerevisiae) and animal cells. The Arabidopsis (Arabidopsis thaliana) protein kinase-associated protein phosphatase includes a FHA domain that mediates interactions with receptor-like kinases, which in turn regulate a variety of signaling pathways involved in plant growth and pathogen responses. Screens for insertional mutations in other Arabidopsis FHA domain-containing genes identified a mutant with pleiotropic defects. dawdle (ddl) plants are developmentally delayed, produce defective roots, shoots, and flowers, and have reduced seed set. DDL is expressed in the root and shoot meristems and the reduced size of the root apical meristem in ddl plants suggests a role early in organ development.

A petal breakstrength meter for Arabidopsis abscission studies

BACKGROUND

Abscission is the regulated dropping of plant organs, such as leaves or flower petals. This process involves a break down of the cell wall between layers of cells in the abscission zone, causing the organ to become detached. The model plant Arabidopsis thaliana undergoes floral organ abscission. Various experimental methods have been used to study Arabidopsis floral organ abscission, including measuring the petal breakstrength, or the amount of force required to pull a petal from the receptacle. Petal breakstrength provides a quantitative insight into the physical integrity of the petal abscission zone.

RESULTS

We developed a petal breakstrength meter that allows rapid data acquisition on a personal computer. We present the design of the device and show its utility in measuring Arabidopsis petal breakstrength for abscission studies.

CONCLUSION

This petal breakstrength meter should enable researchers to perform the petal breakstrength assay as a routine part of the characterization of environmental and genetic factors affecting abscission.

Annual report of the National Influenza Surveillance Scheme, 2005

Surveillance of influenza in Australia is based on laboratory isolation of influenza viruses, sentinel general-practitioner reports of influenza-like illness, and absenteeism data from a major national employer. In 2005, 4,575 cases of laboratory-confirmed influenza-like illness were reported, which was 115 per cent higher than in 2004. The influenza season started in the first week of June, with peak activity in early August, a month earlier than in 2004. Influenza A was the predominant type notified (73%), while influenza B activity continued to increase compared to previous years. During 2005, the influenza notification rate amongst persons aged over 65 years (22 cases per 100,000 population) was 70 per cent higher than the mean rate of the last four years. One thousand one hundred and seventy-four influenza isolates from Australia were antigenically analysed: 689 were A(H3N2), 210 were A(H1N1) strains and 275 were influenza B viruses. Continued antigenic drift was seen with the A(H3N2) viruses from the previous reference strains with approximately one quarter of isolates being distinguishable from A/Wellington/1/2004-like viruses and more closely matched to A/California/7/2004-like viruses.

Early cytokine production is associated with protection from murine cerebral malaria

Cerebral malaria (CM) is an infrequent but serious complication of Plasmodium falciparum infection in humans. Animal and human studies suggest that the pathogenesis of CM is immune mediated, but the precise mechanisms leading to cerebral pathology are unclear. In mice, infection with Plasmodium berghei ANKA results in CM on day 6 postinoculation (p.i.), while infection with the closely related strain P. berghei K173 does not result in CM. Infection with P. berghei K173 was associated with increased plasma gamma interferon (IFN-gamma) at 24 h p.i. and with increased splenic and hepatic mRNAs for a range of cytokines (IFN-gamma, interleukin-10 [IL-10], and IL-12) as well as the immunoregulatory enzyme indoleamine 2,3-dioxygenase. In contrast, P. berghei ANKA infection was associated with an absence of cytokine production at 24 h p.i. but a surge of IFN-gamma production at 3 to 4 days p.i. When mice were coinfected with both ANKA and K173, they produced an early cytokine response, including a burst of IFN-gamma at 24 h p.i., in a manner similar to animals infected with P. berghei K173 alone. These coinfected mice failed to develop CM. In addition, in a low-dose P. berghei K173 infection model, protection from CM was associated with early production of IFN-gamma. Early IFN-gamma production was present in NK-cell-depleted, gammadelta-cell-depleted, and Jalpha281(-/-) (NKT-cell-deficient) mice but absent from beta2-microglobulin mice that had been infected with P. berghei K173. Taken together, the results suggest that the absence of a regulatory pathway involving IFN-gamma and CD8(+) T cells in P. berghei ANKA infection allows the development of cerebral immunopathology.

BAS1 and SOB7 act redundantly to modulate Arabidopsis photomorphogenesis via unique brassinosteroid inactivation mechanisms

Active brassinosteroids (BRs), such as brassinolide (BL) and castasterone (CS), are growth-promoting plant hormones. An Arabidopsis cytochrome P450 monooxygenase (CYP734A1, formerly CYP72B1), encoded by the BAS1 gene, inactivates BRs and modulates photomorphogenesis. BAS1 was identified as the overexpressed gene responsible for a dominant, BR-deficient mutant, bas1-D. This mutant was isolated in an activation-tagged screen designed to identify redundant genes that might not be identified in classic loss-of-function screens. Here we report the isolation of a second activation-tagged mutant with a BR-deficient phenotype. The mutant phenotype is caused by the overexpression of SOB7 (CYP72C1), a homolog of BAS1. We generated single and double null-mutants of BAS1 and SOB7 to test the hypothesis that these two genes act redundantly to modulate photomorphogenesis. BAS1 and SOB7 act redundantly with respect to light promotion of cotyledon expansion, repression of hypocotyl elongation and flowering time in addition to other phenotypes not regulated by light. We also provide biochemical evidence to suggest that BAS1 and SOB7 act redundantly to reduce the level of active BRs, but have unique mechanisms. Overexpression of SOB7 results in a dramatic reduction in endogenous CS levels, and although single null-mutants of BAS1 and SOB7 have the same level of CS as the wild type, the double null-mutant has twice the amount. Application of BL to overexpression lines of BAS1 or SOB7 results in enhanced metabolism of BL, though only BAS1 overexpression lines confer enhanced conversion to 26-OHBL, suggesting that SOB7 and BAS1 convert BL and CS into unique products.

Activation of the WUS gene induces ectopic initiation of floral meristems on mature stem surface in Arabidopsis thaliana

A gain-of-function Arabidopsis mutant was identified via activation tagging genetic screening. The mutant exhibited clustered ectopic floral buds on the surface of inflorescence stems. The mutant was designated as sef for stem ectopic flowers. Our detailed studies indicate that the ectopic flower meristems are initiated from the differentiated cortex cells. Inverse PCR and sequence analysis indicated that the enhancer-containing T-DNA from the activation tagging construct, SKI015, was inserted upstream of the previously cloned WUS gene encoding a homeodomain protein. Studies from RT-PCR, RNA in situ hybridization and transgenic plant analysis further confirmed that the phenotypes of sef are caused by the overexpression of WUS. Our results suggest that overexpression of WUS could trigger the cell pluripotence and reestablish a new meristem in cortex. The type of new meristems caused by WUS overexpression was dependent upon the developmental and physiological stages of a plant. With the help of some undefined factors in the reproductive organs the new meristems differentiated into floral buds. In a vegetative growth plant, however, only the new vegetative buds can be initiated upon the overexpression of WUS. These studies provide new insights of WUS on flower development.