A proliferative burst during preadolescence establishes the final cardiomyocyte number.

It is widely believed that perinatal cardiomyocyte terminal differentiation blocks cytokinesis, thereby causing binucleation and limiting regenerative repair after injury. This suggests that heart growth should occur entirely by cardiomyocyte hypertrophy during preadolescence when, in mice, cardiac mass increases many-fold over a few weeks. Here, we show that a thyroid hormone surge activates the IGF-1/IGF-1-R/Akt pathway on postnatal day 15 and initiates a brief but intense proliferative burst of predominantly binuclear cardiomyocytes. This proliferation increases cardiomyocyte numbers by ~40%, causing a major disparity between heart and cardiomyocyte growth. Also, the response to cardiac injury at postnatal day 15 is intermediate between that observed at postnatal days 2 and 21, further suggesting persistence of cardiomyocyte proliferative capacity beyond the perinatal period. If replicated in humans, this may allow novel regenerative therapies for heart diseases.

HALF FILLED promotes reproductive tract development and fertilization efficiency in Arabidopsis thaliana.

Successful fertilization in angiosperms requires the growth of pollen tubes through the female reproductive tract as they seek out unfertilized ovules. In Arabidopsis, the reproductive tract begins with the stigma, where pollen grains initially adhere, and extends through the transmitting tract of the style and ovary. In wild-type plants, cells within the transmitting tract produce a rich extracellular matrix and undergo programmed cell death to facilitate pollen movement. Here, we show that the HAF, BEE1 and BEE3 genes encode closely related bHLH transcription factors that act redundantly to specify reproductive tract tissues. These three genes are expressed in distinct but overlapping patterns within the reproductive tract, and in haf bee1 bee3 triple mutants extracellular matrix formation and cell death fail to occur within the transmitting tract. We used a minimal pollination assay to show that HAF is necessary and sufficient to promote fertilization efficiency. Our studies further show that HAF expression depends on the NTT gene and on an auxin signaling pathway mediated by the ARF6, ARF8 and HEC genes.

Origins of pressure dependent permeability in unconventional hydrocarbon reservoirs.

Unconventional hydrocarbon assets represent a rapidly expanding proportion of North American oil and gas production. Similar to the incipient phase of conventional oil production at the turn of the twentieth century, there are ample opportunities to improve production efficiency. In this work we demonstrate that pressure dependent permeability degradation exhibited by unconventional reservoir materials is due to the mechanical response of a few commonly encountered microstructural constituents. In particular, the mechanical response of unconventional reservoir materials may be conceptualized as the superposed deformation of matrix (or ~ cylindrical/spherical), and compliant (or slit) pores. The former are representative of pores in a granular medium or a cemented sandstone, while the latter represent pores in an aligned clay compact or a microcrack. As a result of this simplicity, we demonstrate that permeability degradation is accounted for through a weighted superposition of conventional permeability models for these pore architectures. This approach permits us to conclude that the most severe pressure dependence is due to imperceptible bedding parallel delamination cracks in the oil bearing argillaceous (clay-rich) mudstones. Finally, we demonstrate that these delaminations tend to populate layers that are enriched with organic carbon. These findings are a basis for improving recovery factors through the development of new completion techniques to exploit, then mitigate pressure dependent permeability in practice.

The formation and function of the female reproductive tract in flowering plants.

In angiosperms, sexual reproduction requires a sperm cell, contained within a pollen tube, to fertilize the egg cell. The pollen tubes are capable of growth but have a difficult journey, as egg cells are buried within the ovary of the carpel. Several tissues, known collectively as the reproductive tract, develop within the carpel to facilitate the journey of the pollen tube. The genes involved in the formation and function of the reproductive tract have largely remained a mystery but are crucial for successful fertilization. This review summarizes recent advances in our understanding of the genetic control of reproductive tract development.

The NTT gene is required for transmitting-tract development in carpels of Arabidopsis thaliana.

BACKGROUND: The majority of pollen-tube growth in Arabidopsis occurs in specialized tissue called the transmitting tract. Little is currently known about how the transmitting tract functions because of a lack of mutants affecting its development. We have identified such a mutant and we used it to investigate aspects of pollen-tube growth. RESULTS: Reverse genetics was used to identify mutations in a gene, No Transmitting Tract (NTT), encoding a C2H2/C2HC zinc finger transcription factor specifically expressed in the transmitting tract. The ntt mutants have a negative effect on transmitting-tract development. Stage-specific analysis of transmitting-tract development was carried out and was correlated with investigations of pollen-tube behavior. In ntt mutants, pollen tubes grow more slowly and/or terminate prematurely, and lateral divergence is accentuated over apical-to-basal movement. Normal transmitting-tract development is shown to involve a process of programmed cell death (PCD) that is facilitated by, but does not depend upon, pollination. CONCLUSIONS: This is the first report of a gene that is specifically required for transmitting-tract development in Arabidopsis. Mutations in NTT cause reduced fertility by severely inhibiting pollen-tube movement. The data support the idea that the function of the transmitting tract is to increase fertilization efficiency, particularly in the lower half of the ovary. This occurs by facilitating pollen-tube growth through differentiation and then death of transmitting-tract cells.

Physical distancing and risk of COVID-19 in small-scale fisheries: a remote sensing assessment in coastal Ghana.

The novel coronavirus is predicted to have dire implications on global food systems including fisheries value chains due to restrictions imposed on human movements in many countries. In Ghana, food production, both agriculture and fisheries, is exempted from restrictions as an essential service. The enforcement of COVID-19 prevention protocols, particularly social distancing, has been widely reported in Ghana's agricultural markets whereas casual observations and media reports on fish landing sites suggest no such enforcements are in place. This study aimed to provide sound scientific evidence as a basis for informed policy direction and intervention for the artisanal fishing sector in these challenging times. We employed an unmanned aerial vehicle in assessing the risk of artisanal fishers to the pandemic using physical distancing as a proxy. From analysis of cumulative distribution function (G-function) of the nearest-neighbour distances, this study underscored crowding at all surveyed fish landing beaches, and identified potential "hotspots" for disease transmission. Aerial measurements taken at times of peak landing beach activity indicated that the highest proportion of people, representing 56%, 48%, 39% and 78% in Elmina, Winneba, Apam and Mumford respectively, were located at distances of less than one metre from their nearest neighbour. Risk of crowding was independent of the population at the landing beaches, suggesting that all categories of fish landing sites along the coast would require equal urgency and measured attention towards preventing and mitigating the spread of the disease.

Relocation of study participants for rare and ultra-rare disease trials: Ethics and operations.

Clinical trials for investigational new products to treat rare and ultra-rare diseases typically involve a limited number of research sites recruiting from a small pool of patients dispersed over a large geographical area. When remote access is not possible and participants must be present at a trial site, participation in research may require individuals and their families/caregivers to travel great distances, often at significant cost personally and financially and, frequently, for the duration of the trial. This article addresses the ethical and practical issues associated with the practice of sponsors offering financial and other assistance for relocation to trial sites from significant geographical distances, providing both foundational analysis of the ethical issues as well as actionable policy-level guidance on how to best approach these situations.

Identifying network structure similarity using spectral graph theory.

Most real networks are too large or they are not available for real time analysis. Therefore, in practice, decisions are made based on partial information about the ground truth network. It is of great interest to have metrics to determine if an inferred network (the partial information network) is similar to the ground truth. In this paper we develop a test for similarity between the inferred and the true network. Our research utilizes a network visualization tool, which systematically discovers a network, producing a sequence of snapshots of the network. We introduce and test our metric on the consecutive snapshots of a network, and against the ground truth. To test the scalability of our metric we use a random matrix theory approach while discovering Erdös-Rényi graphs. This scaling analysis allows us to make predictions about the performance of the discovery process.

Plant development. Genetic control of distal stem cell fate within root and embryonic meristems.

The root meristem consists of populations of distal and proximal stem cells and an organizing center known as the quiescent center. During embryogenesis, initiation of the root meristem occurs when an asymmetric cell division of the hypophysis forms the distal stem cells and quiescent center. We have identified NO TRANSMITTING TRACT (NTT) and two closely related paralogs as being required for the initiation of the root meristem. All three genes are expressed in the hypophysis, and their expression is dependent on the auxin-signaling pathway. Expression of these genes is necessary for distal stem cell fate within the root meristem, whereas misexpression is sufficient to transform other stem cell populations to a distal stem cell fate in both the embryo and mature roots.

Dysregulation of catalase activity in newborn myocytes during hypoxia is mediated by c-Abl tyrosine kinase.

In the adult heart, catalase (CAT) activity increases appropriately with increasing levels of hydrogen peroxide, conferring cardioprotection. This mechanism is absent in the newborn for unknown reasons. In the present study, we examined how the posttranslational modification of CAT contributes to its activation during hypoxia/ischemia and the role of c-Abl tyrosine kinase in this process. Hypoxia studies were carried out using primary cardiomyocytes from adult (>8 weeks) and newborn rats. Following hypoxia, the ratio of phosphorylated to total CAT and c-Abl in isolated newborn rat myocytes did not increase and were significantly lower (1.3- and 4.2-fold, respectively; P < .05) than their adult counterparts. Similarly, there was a significant association (P < .0005) between c-Abl and CAT in adult cells following hypoxia (30.9 ± 8.2 to 70.7 ± 13.1 au) that was absent in newborn myocytes. Although ubiquitination of CAT was higher in newborns compared to adults following hypoxia, inhibition of this did not improve CAT activity. When a c-Abl activator (5-(1,3-diaryl-1H-pyrazol-4-yl)hydantoin [DPH], 200 µmol/L) was administered prior to hypoxia, not only CAT activity was significantly increased (P < .05) but also phosphorylation levels were also significantly improved (P < .01) in these newborn myocytes. Additionally, ischemia-reperfusion (IR) studies were performed using newborn (4-5 days) rabbit hearts perfused in a Langendorff method. The DPH given as an intracardiac injection into the right ventricle of newborn rabbit resulted in a significant improvement (P < .002) in the recovery of developed pressure after IR, a key indicator of cardiac function (from 74.6% ± 6.6% to 118.7% ± 10.9%). In addition, CAT activity was increased 3.92-fold (P < .02) in the same DPH-treated hearts. Addition of DPH to adult rabbits in contrast had no significant effect (from 71.3% ± 10.7% to 59.4% ± 12.1%). Therefore, in the newborn, decreased phosphorylation of CAT by c-Abl potentially mediates IR-induced dysfunction, and activation of c-Abl may be a strategy to prevent ischemic injury associated with surgical procedures.

Bioactive nanoparticles improve calcium handling in failing cardiac myocytes.

AIMS: To evaluate the ability of N-acetylglucosamine (GlcNAc) decorated nanoparticles and their cargo to modulate calcium handling in failing cardiac myocytes (CMs). MATERIALS & METHODS: Primary CMs isolated from normal and failing hearts were treated with GlcNAc nanoparticles in order to assess the ability of the nanoparticles and their cargo to correct dysfunctional calcium handling in failing myocytes. RESULTS & CONCLUSION: GlcNAc particles reduced aberrant calcium release in failing CMs and restored sarcomere function. Additionally, encapsulation of a small calcium-modulating protein, S100A1, in GlcNAc nanoparticles also showed improved calcium regulation. Thus, the development of our bioactive nanoparticle allows for a 'two-hit' treatment, by which the cargo and also the nanoparticle itself can modulate intracellular protein activity.

Effects of periodontal instrumentation on quality of life and illness in patients with chronic obstructive pulmonary disease: a pilot study.

PURPOSE: To assess if patients with chronic obstructive pulmonary disease (COPD) receiving periodontal debridement for treatment of chronic periodontitis with ultrasonic or hand instrumentation experienced changes in quality of life or incidents of illness following treatment or no treatment. METHODS: The study design was a 3 group, randomized, controlled pre- and post-test experimental pilot study. Volunteers with COPD and chronic periodontitis (n=30) were recruited from physician offices or fliers and randomly assigned to 1 of 3 groups. Of those, 2 groups had periodontal debridement using either magnetostrictive ultrasonic instrumentation (n=10) or hand instrumentation (n=10). A control group (n=10) received no treatment. Primary outcomes, quality of life and illness were measured by the St. George's Respiratory Questionnaire (SGRQ-A) and Illness Questionnaire, respectively. Subjects completed the questionnaires as pre-tests at baseline and as post-tests 4 weeks post-treatment/no treatment. Repeated measures ANOVA was used to compare groups on continuous variables (p ≤ 0.05) measured by SGRQ-A total scores and symptoms, activities and impacts subscales. Percentages, frequencies and cross tabulations were calculated for categorical data. RESULTS: SGRQ-A and Illness Questionnaire scores showed no significant differences between groups in quality of life or illness following periodontal debridement. Total SGRQ-A scores decreased slightly for all groups with no significant difference among groups (p=0.138) and no interaction (p=0.794). Cross tabulations showed no relationship between indicators of self-reported illness before and after treatment/no treatment. No adverse events were reported. CONCLUSION: Based on this small-scale study, it seems periodontal debridement for chronic periodontitis has no effect on quality of life and illness in patients with COPD, and it may be performed with ultrasonic or hand instruments without adverse events.

Cardioprotection from oxidative stress in the newborn heart by activation of PPARγ is mediated by catalase.

Regulation of catalase (CAT) by peroxisome proliferator-activated receptor-γ (PPARγ) was investigated to determine if PPARγ activation provides cardioprotection from oxidative stress caused by hydrogen peroxide (H(2)O(2)) in an age-dependent manner. Left ventricular developed pressure (LVDP) was measured in Langendorff perfused newborn or adult rabbit hearts, exposed to 200µM H(2)O(2), with perfusion of rosiglitazone (RGZ) or pioglitazone (PGZ), PPARγ agonists. We found: (1) H(2)O(2) significantly decreased sarcomere shortening in newborn ventricular cells but not in adult cells. Lactate dehydrogenase (LDH) release occurred earlier in newborn than in adult heart, which may be due, in part, to the lower expression of CAT in newborn heart. (2) RGZ increased CAT mRNA and protein as well as activity in newborn but not in adult heart. GW9662 (PPARγ blocker) eliminated the increased CAT mRNA by RGZ. (3) In newborn heart, RGZ and PGZ treatment inhibited release of LDH in response to H(2)O(2) compared to H(2)O(2) alone. GW9662 decreased this inhibition. (4) LVDP was significantly higher in both RGZ+H(2)O(2) and PGZ+H(2)O(2) groups than in the H(2)O(2) group. Block of PPARγ abolished this effect. In contrast, there was no effect of RGZ in adult. (5) The cardioprotective effects of RGZ were abolished by inhibition of CAT. In conclusion, PPARγ activation is cardioprotective to H(2)O(2)-induced stress in the newborn heart by upregulation of catalase. These data suggest that PPARγ activation may be an effective therapy for the young cardiac patient.

Stretch-activated channel activation promotes early afterdepolarizations in rat ventricular myocytes under oxidative stress.

Mechanical stretch and oxidative stress have been shown to prolong action potential duration (APD) and produce early afterdepolarizations (EADs). Here, we developed a simulation model to study the role of stretch-activated channel (SAC) currents in triggering EADs in ventricular myocytes under oxidative stress. We adapted our coupling clamp circuit so that a model ionic current representing the actual SAC current was injected into ventricular myocytes and added as a real-time current. This current was calculated as I(SAC) = G(SAC) * (V(m) - E(SAC)), where G(SAC) is the stretch-activated conductance, V(m) is the membrane potential, and E(SAC) is the reversal potential. In rat ventricular myocytes, application of G(SAC) did not produce sustained automaticity or EADs, although turn-on of G(SAC) did produce some transient automaticity at high levels of G(SAC). Exposure of myocytes to 100 microM H(2)O(2) induced significant APD prolongation and increase in intracellular Ca(2+) load and transient, but no EAD or sustained automaticity was generated in the absence of G(SAC). However, the combination of G(SAC) and H(2)O(2) consistently produced EADs at lower levels of G(SAC) (2.6 +/- 0.4 nS, n = 14, P < 0.05). Pacing myocytes at a faster rate further prolonged APD and promoted the development of EADs. SAC activation plays an important role in facilitating the development of EADs in ventricular myocytes under acute oxidative stress. This mechanism may contribute to the increased propensity to lethal ventricular arrhythmias seen in cardiomyopathies, where the myocardium stretch and oxidative stress generally coexist.

The risks and impacts of portering on the well-being of children in Nepal.

A variety of underlying conditions increase the likelihood of children entering the labor force. Nearly half of Nepal's population between 5 and 14 years of age is economically active, many in conditions classified by the International Labor Organization as 'the worst forms of child labor'. In order to assess the relationship between portering and well-being outcomes, including diet, nutrition status, injury and social and behavioral risks, a cross-sectional study was conducted among long distance child porters in Eastern Nepal. Porters were consistently less well off than their non-portering peers according to a variety of indicators. Porters were 2.2 (95% CI: 1.4-3.4) times as likely not to have attended school in the past month and frequency of attendance was significantly lower among porters. Porters had worse diets and significantly lower Body mass indexes than controls; prevalence of anemia was 30% and the risk of anemia was 1.9 (95% CI: 1.1-3.1) times greater for porters as compared with controls. Injury rates within the past year were similar between the two groups, with 88% of participants reporting being injured. Prevalence of alcohol use among porters was 38% and porters were 2.9 (95 CI: 1.7-4.9) times more likely to consume alcohol than controls. Risk of sexual assault was 10.1 (95 CI: 2.3-43.9) times greater among porters as compared with their non-portering peers, and 91% indicated they felt portering negatively impacted their general well-being. Findings indicate that despite the Nepalese government's legislative efforts to regulate to the portering industry, portering children experience a substantially increased risk of negative physical, emotional and educational outcomes due to their involvement in exploitive and dangerous work. The long-term ramifications of portering are harmful to the well-being of children, and in the long run, lack of education may reduce employment options and the chance to escape from a life of continued poverty.

Evidence of a genomic biomarker in normal human epithelial mammary cell line, MCF-10A, that is absent in the human breast cancer cell line, MCF-7.

This study investigated the use of DNA amplification fingerprinting (DAF) to identify biomarkers useful in the elucidating genetic factors that lead to carcinogenesis. The DNA amplification fingerprinting (DAF) technique was used to generate fingerprint profiles of a normal human mammary epithelial cell line (MCF-10A) and a human breast cancer cell line (MCF-7). When compared with one another, a polymorphic biomarker gene (262 base pairs (bps)) was identified in MCF-10A but was not present in MCF-7. This gene was cloned from the genomic DNA of the MCF-10A cell line, and subjected to Genbank database analysis. The analysis of the nucleotide sequence polymorphic marker (Genbank account: AC079630) shows that this biomarker has 100% homology with the nucleotide sequence of human chromosome 12 BAC RP11-476D10 (bps 19612-19353). The nucleotide sequence was used for possible protein translation product and the result obtained indicated that the gene codes for hypothetical protein XF2620. In order to evaluate the effects that the 262 bps biomarker would have on the morphology of MCF-7 cells, it was transfected into MCF-7 cells. There were observable changes in the morphology of the transfected cells. These changes included an increase in cell elongation and a decrease in cell aggregation.

Dephosphorylation specificities of protein phosphatase for cardiac troponin I, troponin T, and sites within troponin T.

Protein dephosphorylation by protein phosphatase 1 (PP1), acting in concert with protein kinase C (PKC) and protein kinase A (PKA), is a pivotal regulatory mechanism of protein phosphorylation. Isolated rat cardiac myofibrils phosphorylated by PKC/PKA and dephosphorylated by PP1 were used in determining dephosphorylation specificities, Ca(2+)-stimulated Mg(2+)ATPase activities, and Ca(2+) sensitivities. In reconstituted troponin (Tn) complex, PP1 displayed distinct substrate specificity in dephosphorylation of TnT preferentially to TnI, in vitro. In situ phosphorylation of cardiomyocytes with calyculin A, a protein phosphatase inhibitor, resulted in an increase in the phosphorylation stiochiometry of TnT (0.3 to 0.5 (67%)), TnI (2.6 to 3.6 (38%)), and MLC2 (0.4 to 1.7 (325%)). These results further confirmed that though MLC2 is the preferred target substrate for protein phosphatase in the thick filament, the Tn complex (TnI and TnT) from thin filament and C-protein in the thick filament are also protein phosphatase substrates. Our in vitro dephosphorylation experiments revealed that while PP1 differentially dephosphorylated within TnT at multiple sites, TnI was uniformly dephosphorylated. Phosphopeptide maps from the in vitro experiments show that TnT phosphopeptides at spots 4A and 4B are much more resistant to PP1 dephosphorylation than other TnT phosphopeptides. Mg(2+)ATPase assays of myofibrils phosphorylated by PKC/PKA and dephosphorylated by PP1 delineated that while PKC and PKA phosphorylation decreased the Ca(2+)-stimulated Mg(2+)ATPase activities, dephosphorylation antagonistically restored it. PKC and PKA phosphorylation decreased Ca(2+) sensitivity to 3.6 microM and 5.0 microM respectively. However, dephosphorylation restored the Mg(2+)ATPase activity of PKC (99%) and PKA (95%), along with the Ca(2+) sensitivities (3.3 microM and 3.0 microM, respectively).

A streamlined method for systematic, high resolution in situ analysis of mRNA distribution in plants.

BACKGROUND: In situ hybridisation can provide cellular, and in some cases sub-cellular, resolution of mRNA levels within multicellular organisms and is widely used to provide spatial and temporal information on gene expression. However, standard protocols are complex and laborious to implement, restricting analysis to one or a few genes at any one time. Whole-mount and reverse transcriptase-PCR (RT-PCR) based protocols increase throughput, but can compromise both specificity and resolution. With the advent of genome-wide analysis of gene expression, there is an urgent need to develop high-throughput in situ methods that also provide high resolution. RESULTS: Here we describe the development of a method for performing high-throughput in situ hybridisations that retains both the high resolution and the specificity of the best manual versions. This refined semi-automated protocol has the potential for determining the spatial and temporal expression patterns of hundreds of genes in parallel on a variety of tissues. We show how tissue sections can be organized on microscope slides in a manner that allows the screening of multiple probes on each slide. Slide handling, hybridisation and processing steps have been streamlined providing a capacity of at least 200 probes per week (depending on the tissue type). The technique can be applied easily to different species and tissue types, and we illustrate this with wheat seed and Arabidopsis floral meristems, siliques and seedlings. CONCLUSION: The approach has the high specificity and high resolution of previous in situ methods while allowing for the analysis of several genes expression patterns in parallel. This method has the potential to provide an analysis of gene expression patterns at the genome level.