The CIN-TCP transcription factors promote commitment to differentiation in Arabidopsis leaf pavement cells via both auxin-dependent and independent pathways.

Cells in organ primordia undergo active proliferation at an early stage to generate sufficient number, before exiting proliferation and entering differentiation. However, how the actively proliferating cells are developmentally reprogrammed to acquire differentiation potential during organ maturation is unclear. Here, we induced a microRNA-resistant form of TCP4 at various developmental stages of Arabidopsis leaf primordium that lacked the activity of TCP4 and its homologues and followed its effect on growth kinematics. By combining this with spatio-temporal gene expression analysis, we show that TCP4 commits leaf cells within the transition zone to exit proliferation and enter differentiation. A 24-hour pulse of TCP4 activity was sufficient to impart irreversible differentiation competence to the actively dividing cells. A combination of biochemical and genetic analyses revealed that TCP4 imparts differentiation competence by promoting auxin response as well as by directly activating HAT2, a HD-ZIP II transcription factor-encoding gene that also acts downstream to auxin response. Our study offers a molecular link between the two major organ maturation factors, CIN-like TCPs and HD-ZIP II transcription factors and explains how TCP activity restricts the cell number and final size in a leaf.

Physiological and Transcriptomic Analysis of Arabidopsis thaliana Responses to Ailanthone, a Potential Bio-Herbicide.

Many plants naturally synthesize and secrete secondary metabolites that exert an allelopathic effect, offering compelling alternatives to chemical herbicides. These natural herbicides are highly important for sustainable agricultural practices. Ailanthone is the chemical responsible for the herbicidal effect of Ailanthus altissima, or "tree of heaven". The molecular studies involving ailanthone's effect on plant growth are limited. In the current study, we combined whole-transcriptome and physiology analysis of three Arabidopsis thaliana ecotypes treated with ailanthone to identify the effect of this allelopathic chemical on genes and plant growth. Our physiology results showed 50% reduced root growth, high proline accumulation, and high reactive-oxygen-species accumulation in response to ailanthone stress. Deep transcriptome analysis revealed 528, 473, and 482 statistically significant differentially expressed genes for Col-0, Cvi-0, and U112-3 under ailanthone stress, including 131 genes shared among the three accessions. The common genes included 82 upregulated and 42 downregulated genes and varied in expression at least twofold. The study also revealed that 34 of the 131 genes had a similar expression pattern when Arabidopsis seedlings were subjected to other herbicides. Differentially expressed genes significantly induced in response to ailanthone included DTXL1, DTX1, ABCC3, NDB4, UGT74E2, and AZI1. Pathways of stress, development and hormone metabolism were significantly altered under ailanthone stress. These results suggest that ailanthone triggers a significant stress response in multiple pathways similar to other herbicides.

The TCP4 Transcription Factor Directly Activates TRICHOMELESS1 and 2 and Suppresses Trichome Initiation.

Trichomes are the first line of defense on the outer surface of plants against biotic and abiotic stresses. Because trichomes on leaf surfaces originate from the common epidermal progenitor cells that also give rise to pavement cells and stomata, their density and distribution are under strict genetic control. Regulators of trichome initiation have been identified and incorporated into a biochemical pathway wherein an initiator complex promotes trichome fate in an epidermal progenitor cell, while an inhibitor complex suppresses it in the neighboring cells. However, it is unclear how these regulator proteins, especially the negative regulators, are induced by upstream transcription factors and integrated with leaf morphogenesis. Here, we show that the Arabidopsis (Arabidopsis thaliana) class II TCP proteins activate TRICHOMELESS1 (TCL1) and TCL2, the two established negative regulators of trichome initiation, and reduce trichome density on leaves. Loss-of-function of these TCP proteins increased trichome density whereas TCP4 gain-of-function reduced trichome number. TCP4 binds to the upstream regulatory elements of both TCL1 and TCL 2 and directly promotes their transcription. Further, the TCP-induced trichome suppression is independent of the SQUAMOSA PROMOTER BINDING PROTEIN LIKE family of transcription factors, proteins that also reduce trichome density at later stages of plant development. Our work demonstrates that the class II TCP proteins couple leaf morphogenesis with epidermal cell fate determination.

The TCP4 transcription factor regulates trichome cell differentiation by directly activating GLABROUS INFLORESCENCE STEMS in Arabidopsis thaliana.

Trichomes are the first cell type to be differentiated during the morphogenesis of leaf epidermis and serve as an ideal model to study cellular differentiation. Many genes involved in the patterning and differentiation of trichome cells have been studied over the past decades, and the majority of these genes encode transcription factors that specifically regulate epidermal cell development. However, the upstream regulators of these genes that link early leaf morphogenesis with cell type differentiation are less studied. The TCP proteins are the plant-specific transcription factors involved in regulating diverse aspects of plant development including lateral organ morphogenesis by modulating cell proliferation and differentiation. Here, we show that the miR319-regulated class II TCP proteins, notably TCP4, suppress trichome branching in Arabidopsis leaves and inflorescence stem by direct transcriptional activation of GLABROUS INFLORESCENCE STEMS (GIS), a known negative regulator of trichome branching. The trichome branch number is increased in plants with reduced TCP activity and decreased in the gain-of-function lines of TCP4. Biochemical analyses show that TCP4 binds to the upstream regulatory region of GIS and activates its expression. Detailed genetic analyses show that GIS and TCP4 work in same pathway and GIS function is required for TCP4-mediated regulation of trichome differentiation. Taken together, these results identify a role for the class II TCP genes in trichome differentiation, thus providing a connection between organ morphogenesis and cellular differentiation.

Activation of YUCCA5 by the Transcription Factor TCP4 Integrates Developmental and Environmental Signals to Promote Hypocotyl Elongation in Arabidopsis.

Cell expansion is an essential process in plant morphogenesis and is regulated by the coordinated action of environmental stimuli and endogenous factors, such as the phytohormones auxin and brassinosteroid. Although the biosynthetic pathways that generate these hormones and their downstream signaling mechanisms have been extensively studied, the upstream transcriptional network that modulates their levels and connects their action to cell morphogenesis is less clear. Here, we show that the miR319-regulated TCP (TEOSINTE BRANCHED1, CYCLODEA, PROLIFERATING CELL FACTORS) transcription factors, notably TCP4, directly activate YUCCA5 transcription and integrate the auxin response to a brassinosteroid-dependent molecular circuit that promotes cell elongation in Arabidopsis thaliana hypocotyls. Furthermore, TCP4 modulates the common transcriptional network downstream to auxin-brassinosteroid signaling, which is also triggered by environmental cues, such as light, to promote cell expansion. Our study links TCP function with the hormone response during cell morphogenesis and shows that developmental and environmental signals converge on a common transcriptional network to promote cell elongation.

Polymorphism of Polymeric Amino Acid Regions in Fungal Proteins and Correlation with Altered Echinocandin and Azole Susceptibility.

Polymorphism of polymeric amino acid (polyX) regions within fungal proteins represents a potential mechanism for rapid genotypic adaptation to environmental pressures, including antifungal exposure. Polyglutamine (polyQ) was the most abundant repeat in the proteomes of 8 diverse fungal species and was preferentially found in regulatory proteins. In Candida glabrata, polyX polymorphisms were characterized in 36 proteins implicated in azole or echinocandin susceptibility. General transcriptional repressor Tup1A exhibited Q44/Q45 polymorphism, and Hog1 signaling component Ssk2 exhibited N44/N45 polymorphism in phylogenetically matched echinocandin- and azole-susceptible/resistant strains, respectively.

Design, semisynthesis and cytotoxic activity of novel ester derivatives of betulinic acid-1,2,4 oxadiazoles.

Taking into consideration of the biological activity of betulinic acid derivatives containing a oxadiazole ring, the semisynthetic betulinic acid-1,2,4-oxadiazole esters (14-25) were synthesized starting from betulinic acid (1) and 5-(bromomethyl)-3-aryl-1,2,4-oxadiazoles (2-13) and final compounds were tested for cytotoxic activity on three human cancer cell lines in vitro. All tested compounds showed good cytotoxic activity. The structures of synthesized compounds are established based on infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry.

Sphingolipids mediate differential echinocandin susceptibility in Candida albicans and Aspergillus nidulans.

The cell wall synthesis-inhibiting echinocandins, including caspofungin and micafungin, play important roles in the treatment of candidiasis and aspergillosis. Previous studies revealed that, in the haploid yeast Candida glabrata, sphingolipid biosynthesis pathway mutations confer caspofungin reduced susceptibility (CRS) but micafungin increased susceptibility (MIS). Here, we describe one Candida albicans strain (of 10 tested) that similarly yields CRS-MIS mutants at relatively high frequency. Mutants demonstrated increased levels of long-chain bases (sphingolipid pathway intermediates) and, unique to this strain, loss of His104/Pro104 heterozygosity in the TSC13-encoded enoyl reductase. CRS-MIS was similarly observed in a C. albicans homozygous fen1Δ fen12Δ laboratory strain and in diverse wild-type strains following exogenous long-chain-base treatment. Analogous to these results, CRS-MIS was demonstrated in an Aspergillus nidulans basA mutant encoding defective sphingolipid C4-hydroxylase and in its wild-type parent exposed to long-chain bases. Sphingolipids likely modulate echinocandin interaction with their Fks membrane target in all susceptible fungi, with potential implications for optimizing therapy with existing antifungals and the development of novel agents.

The tarani mutation alters surface curvature in Arabidopsis leaves by perturbing the patterns of surface expansion and cell division.

The leaf surface usually stays flat, maintained by coordinated growth. Growth perturbation can introduce overall surface curvature, which can be negative, giving a saddle-shaped leaf, or positive, giving a cup-like leaf. Little is known about the molecular mechanisms that underlie leaf flatness, primarily because only a few mutants with altered surface curvature have been isolated and studied. Characterization of mutants of the CINCINNATA-like TCP genes in Antirrhinum and Arabidopsis have revealed that their products help maintain flatness by balancing the pattern of cell proliferation and surface expansion between the margin and the central zone during leaf morphogenesis. On the other hand, deletion of two homologous PEAPOD genes causes cup-shaped leaves in Arabidopsis due to excess division of dispersed meristemoid cells. Here, we report the isolation and characterization of an Arabidopsis mutant, tarani (tni), with enlarged, cup-shaped leaves. Morphometric analyses showed that the positive curvature of the tni leaf is linked to excess growth at the centre compared to the margin. By monitoring the dynamic pattern of CYCLIN D3;2 expression, we show that the shape of the primary arrest front is strongly convex in growing tni leaves, leading to excess mitotic expansion synchronized with excess cell proliferation at the centre. Reduction of cell proliferation and of endogenous gibberellic acid levels rescued the tni phenotype. Genetic interactions demonstrated that TNI maintains leaf flatness independent of TCPs and PEAPODs.

CINCINNATA-Like TCP Transcription Factors in Cell Growth - An Expanding Portfolio.

Post-mitotic cell growth is a key process in plant growth and development. Cell expansion drives major growth during morphogenesis and is influenced by both endogenous factors and environmental stimuli. Though both isotropic and anisotropic cell growth can contribute to organ size and shape at different degrees, anisotropic cell growth is more likely to contribute to shape change. While much is known about the mechanisms that increase cellular turgor and cell-wall biomass during expansion, the genetic factors that regulate these processes are less studied. In the past quarter of a century, the role of the CINCINNATA-like TCP (CIN-TCP) transcription factors has been well documented in regulating diverse aspects of plant growth and development including flower asymmetry, plant architecture, leaf morphogenesis, and plant maturation. The molecular activity of the CIN-TCP proteins common to these biological processes has been identified as their ability to suppress cell proliferation. However, reports on their role regulating post-mitotic cell growth have been scanty, partly because of functional redundancy among them. In addition, it is difficult to tease out the effect of gene activity on cell division and expansion since these two processes are linked by compensation, a phenomenon where perturbation in proliferation is compensated by an opposite effect on cell growth to keep the final organ size relatively unaltered. Despite these technical limitations, recent genetic and growth kinematic studies have shown a distinct role of CIN-TCPs in promoting cellular growth in cotyledons and hypocotyls, the embryonic organs that grow solely by cell expansion. In this review, we highlight these recent advances in our understanding of how CIN-TCPs promote cell growth.

The effect of 3-nitrooxypropanol, a potent methane inhibitor, on ruminal microbial gene expression profiles in dairy cows.

BACKGROUND: Enteric methane emissions from dairy cows are an environmental problem as well as a gross feed energy loss to the animal. Methane is generated in the rumen by methanogenic archaea from hydrogen (H2) + carbon dioxide and from H2 + methanol or methylamines. The methanogenic substrates are provided by non-methanogens during feed fermentation. Methane mitigation approaches have yielded variable results, partially due to an incomplete understanding of the contribution of hydrogenotrophic and methylotrophic archaea to methanogenesis. Research indicates that 3-nitrooxypropanol (3-NOP) reduces enteric methane formation in dairy cows by inhibiting methyl-coenzyme M reductase (MCR), the enzyme responsible for methane formation. The purpose of this study was to utilize metagenomic and metatranscriptomic approaches to investigate the effect of 3-NOP on the rumen microbiome and to determine the fate of H2 that accumulates less than expected under inhibited methanogenesis. RESULTS: The inhibitor 3-NOP was more inhibitory on Methanobrevibacter species than methanol-utilizing Methanosphaera and tended to reduce the gene expression of MCR. Under inhibited methanogenesis by 3-NOP, fluctuations in H2 concentrations were accompanied by changes in the expression of [FeFe] hydrogenases in H2-producing bacteria to regulate the amount of H2 production. No previously reported alternative H2 sinks increased under inhibited methanogenesis except for a significant increase in gene expression of enzymes involved in the butyrate pathway. CONCLUSION: By taking a metatranscriptomic approach, this study provides novel insights on the contribution of methylotrophic methanogens to total methanogenesis and regulation of H2 metabolism under normal and inhibited methanogenesis by 3-NOP in the rumen. Video Abstract.

Modern techniques of teaching and learning in medical education: a descriptive literature review.

This article was migrated. The article was marked as recommended. OBJECTIVES: Education is a dynamic process that has to be refined periodically. Lack of innovative teaching techniques in academics makes medical curricula inadequate in making a significant stride towards the future. The objective of this review is to describe and assess alternative methods of teaching and learning which can be supplementive or alternative to traditional lectures for promoting active student participation and smooth flow of information. METHODS: A review of literature is performed with PubMed and EBSCO using the keywords: "learning" OR "didactic learning" OR "alternative learning" OR "modern learning techniques" AND "medical education". Databases were searched and 500 studies were identified out of which 200 were selected for further screening based on inclusion criteria and exclusion criteria. Articles were surveyed based on their relevance and significance to our study objectives with both qualitative and quantitative studies were examined. RESULTS: Case-based learning, evidence-based medicine, problem-based learning, simulation-based learning, e-learning, peer-assisted learning, observational learning, flipped classroom and team based learning are some of the modern learning methodologies. The various learning methods discussed attend to individual learning differences allowing students to broaden their thinking and professional knowledge by improving logical and critical thinking, clinical reasoning, and time management. Early introduction of integrative approaches develop student competency and leadership equipping students for a smooth transit into the clinical practice. CONCLUSION: This study highlights the importance and challenges of modern learning systems. With technological advancement and wider implications of medical information, students require innovative skills through inter-professional learning. It is necessary to introduce and implement flexible medical curricula that accommodates distinct modern teaching to effectively balance and bridge the gap between traditional teaching methodologies and modern educational requirements.

Impact of accreditation on Caribbean medical schools' processes.

BACKGROUND: Caribbean graduates contribute significantly to the US healthcare workforce. The accreditation requirements of local governments vary from one Caribbean island to another island. The Educational Commission for Foreign Medical Graduates (ECFMG) requirement that all future applicants be graduates from accredited medical schools drove Caribbean medical schools to seek accreditation. Accreditation has been found to significantly impact the educational processes of Canadian medical schools. Our study aims at investigating Caribbean medical school leaders' perceptions of the impact of accreditation on their school's processes. METHODS: This qualitative study and data analysis were done using a framework analysis. Academic leaders and faculty members from three different types of Caribbean medical schools (accredited, denied-accreditation schools, never applied for accreditation) were interviewed using semi-structured interviews. RESULTS: A total of 12 participants from six different Caribbean medical schools participated in the interview process. Themes of processes influenced by accreditation at Caribbean medical schools were similar to those found in the Canadian context and align with best practices of Continuous Quality Improvement (CQI). CONCLUSIONS: Caribbean medical schools are changing their educational processes as a result of accreditation requirements. Some processes are not maintained in a continuous manner, raising questions about the development of a true CQI culture.

CONTEXTE: Les diplômés des Caraïbes contribuent de manière significative au personnel de santé Américain. Les exigences des gouvernements Caraïbes en matière d'agrément varient d'une île à l'autre. L'Educational Commission for Foreign Medical Graduates, ECFMG (Commission de l'éducation pour les diplômés en médecine étrangers), exige que les candidats soient diplômés de facultés de médecine agréées, ce qui a incité les facultés de médecine des Caraïbes à solliciter l'agrément. Il a été démontré que l'agrément affectait de manière importante les processus éducatifs des écoles de médecine canadiennes. Notre étude vise à examiner les perceptions des directions des facultés de médecine des Caraïbes quant aux répercussions de l'agrément sur leurs processus. MÉTHODES: La présente étude qualitative et l'analyse des données ont été réalisées selon la méthodologie du cadre logique. Les responsables universitaires et les membres du corps professoral de facultés de médecine des Caraïbes se trouvant dans trois cas de figure différents (facultés agrées, facultés auxquelles l'agrément a été refusé et facultés n'ayant jamais sollicité l'agrément) ont été interrogés par le biais d'entretiens semi-structurées. RÉSULTATS: Douze participants de six facultés de médecine de la région des Caraïbes ont participé aux entretiens. Des thèmes similaires se dégagent en ce qui concerne les processus influencés par l'agrément dans les facultés de médecine caribéennes et canadiennes, en particulier l'adoption des pratiques exemplaires en matière d'amélioration continue de la qualité (ACQ). CONCLUSIONS: Les facultés de médecine des Caraïbes modifient leurs processus éducatifs afin de remplir les exigences d'agrément. Certains processus ne sont pas maintenus de manière continue, ce qui soulève des interrogations quant à l'implantation d'une véritable culture de l'ACQ.

Active suppression of leaflet emergence as a mechanism of simple leaf development.

Angiosperm leaves show extensive shape diversity and are broadly divided into two forms; simple leaves with intact lamina and compound leaves with lamina dissected into leaflets. The mechanistic basis of margin dissection and leaflet initiation has been inferred primarily by analysing compound-leaf architecture, and thus whether the intact lamina of simple leaves has the potential to initiate leaflets upon endogenous gene inactivation remains unclear. Here, we show that the CINCINNATA-like TEOSINTE BRANCHED1, CYCLOIDEA, PROLIFERATING CELL FACTORS (CIN-TCP) transcription factors activate the class II KNOTTED1-LIKE (KNOX-II) genes and the CIN-TCP and KNOX-II proteins together redundantly suppress leaflet initiation in simple leaves. Simultaneous downregulation of CIN-TCP and KNOX-II in Arabidopsis leads to the reactivation of the stemness genes KNOX-I and CUPSHAPED COTYLEDON (CUC) and triggers ectopic organogenesis, eventually converting the simple lamina to a super-compound form that appears to initiate leaflets indefinitely. Thus, a conserved developmental mechanism promotes simple leaf architecture in which CIN-TCP-KNOX-II forms a strong differentiation module that suppresses the KNOX-I-CUC network and leaflet initiation.

Epidemiological Differences of COVID-19 Over the World.

Background Coronavirus disease 2019 (COVID-19), originally, from Wuhan, China, has now spread to most countries across the globe and devastated global healthcare systems. The impact of this disease has, however, shown baffling variations in prevalence in different regions of the world. The aim of this short review is to identify differential national COVID-19 prevalence of COVID-19, as well as to suggest these epidemiological differences.  Methods A review of studies was conducted using PubMed and Google Scholar search engines. Search tactics were centered on COVID-19 ("COVID-19" AND "coronavirus") and BCG vaccination ("BCG vaccination" OR "Bacillus Calmette-Guérin" OR "vaccine") Results It is found that national prevalence differences may be linked with BCG childhood immunization history. A statistically insignificant difference was observed in COVID-19 prevalence when comparing countries with a BGC policy and countries without it (P> 0.05). This inconclusivity suggests the influence of confounders in this study. Conclusions National differences in COVID-19 cases can be attributable to immunologic regulations, such as BCG vaccination protocols. Caution should be taken in establishing a correlation between COVID-19 prevalence and BCG vaccination, partly due to the weak quality of statistical data on COVID-19 related to poor testing rates in countries with BCG vaccination policy. Nonetheless, the analysis of the epidemiological aspects of COVID-19 will shed light on future efforts towards effective control and prevention.

Escalation of an Otherwise Curable Cancer: Retroperitoneal Mass Destruction Associated With Testicular Seminoma in a Psychiatric Patient.

We report the case of a 31-year-old male patient with underlying psychiatric illness and substance abuse who presented to the emergency department with a chief complaint of abdominal pain. CT scan of the abdomen revealed a large retroperitoneal mass wrapping around the aorta and obstructing the left ureter causing hydronephrosis. Physical examination found a painless left testicular mass. The ultrasound revealed a left scrotal mass measuring 32 x 24 x 16 mm with evidence of increased vascularity and calcifications. The patient underwent ureteral stent placement and left testicular orchiectomy with the pathology evaluation revealing seminoma. Although follow-up care plans were made, the patient relapsed IV heroin abuse causing failure to attend oncological treatment appointments. Two months later upon readmission, a repeat of the CT scan of the abdomen and pelvis showed a persistent large left retroperitoneal mass with an increase in size and significant mass effect. The patient would be ultimately considered for hospice if lack of compliance were to continue for his chemotherapy, along with his comorbid underlying substance abuse and psychiatric illness. This case highlights the effect of mental illness on medical care and treatment, demonstrating how a treatable malignancy may result in greater morbidity and mortality in psychiatric populations.

Lack of Patient Knowledge Regarding the Adverse Effects of Analgesics With High Doses Leading to Elevation of Creatinine and Major Consequences - A Case Report.

We present a case of a 49-year-old male with complaints of back pain and not being able to urinate. The patient was suffering from back pain for the last four days and followed up with the chiropractor, but the pain persisted. The patient took eight ibuprofen tablets (1600 mg) within those four days to relieve the pain. Lab workup showed a blood urea nitrogen (BUN) of 175 mg/dL, creatinine level of 32.87mg/dL, and an anion gap metabolic acidosis. With close monitoring and dialysis in the hospital, the creatinine came down to 11.92mg/dL. Ultrasound-guided renal biopsy showed that the patient developed acute interstitial nephritis. The patient was treated with prednisone and later discharged with a creatinine level of 8.60mg/dL. Before he was discharged, he was declared to have end-stage renal disease and placed on outpatient dialysis. Only a few case reports are recorded in the literature with such a high elevation of creatinine levels.

Molecular cartography of leaf development - role of transcription factors.

Organ elaboration in plants occurs almost exclusively by an increase in cell number and size. Leaves, the planar lateral appendages of plants, are no exception. Forward and reverse genetic approaches have identified several genes whose role in leaf morphogenesis has been inferred from their primary effect on cell number and size, thereby distinguishing them as either promoters or inhibitors of cell proliferation and expansion. While such classification is useful in studying size control, a similar link between genes and shape generation is poorly understood. Computational modelling can provide a conceptual framework to re-evaluate the known genetic information and assign specific morphogenetic roles to the transcription factor-encoding genes. Here we discuss recent advances in our understanding of the roles of transcription factors in the planar growth of leaf lamina in two orthogonal dimensions.

Generation of Inducible Transgenic Lines of Arabidopsis Transcription Factors Regulated by MicroRNAs.

Transcription factors play key regulatory roles in all the life processes across kingdoms. In plants, the genome of a typical model species such as Arabidopsis thaliana encodes over 1500 transcription factors that regulate the expression dynamics of all the genes in time and space. Therefore, studying their function by analyzing the loss and gain-of-function lines is of prime importance in basic plant biology and its agricultural application. However, the current approach of knocking out genes often causes embryonic lethal phenotype, while inactivating one or two members of a redundant gene family yields little phenotypic changes, thereby making the functional analysis a technically challenging task. In such cases, inducible knock-down or overexpression of transcription factors appears to be a more effective approach. Restricting the transcription factors in the cytoplasm by fusing them with animal glucocorticoid/estrogen receptors (GR/ER) and then re-localizing them to the nucleus by external application of animal hormone analogues has been a useful method of gene function analysis in the model plants. In this chapter, we describe the recent advancements in the GR and ER expression systems and their use in analyzing the function of transcription factors in Arabidopsis.