Young Stem Research Articles

Botanical and genetic characters of Erythrina × neillii cultivated in Egypt

Erythrina×neillii Mabberley & Lorence, Fabaceae, is a sterile hybrid between E. herbacea L. and E. humeana Spreng. Nothing was traced about its genetic, macro and micromorphology. Therefore, it was deemed of interest to study its botanical characters, in addition to the DNA fingerprint to help in the identification of the plant. The anatomical characters of the old stem and its bark are characterized by the presence of cork cells, bast fibers and sclereids. Pericycle is sclerenchymatous forming crystal sheath. The epidermises of the leaf and young stem are characterized by the presence of anomocytic and paracytic stomata, non-glandular, unicellular and multicellular two armed hairs, and glandular club shaped hair. Calcium oxalate is present in the form of crystal sheath and prisms. Secretory cavities are distributed in the phloem and cortex. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used as one of the molecular methods to differentiate between the samples of Erythrina. The DNA of Erythrina was extracted and analyzed using seven-mer random primers. Randomly Amplified Polymorphic DNA were recognized. This characterization allows certification of the authenticity of Erythrina×neillii, in order to provide quality control for the plant.

Anatomy and Morphological Study of Mentigi Gunung (Vaccinium varingiaefolium (Blume) Miq.) in Area of Mount Batok-Indonesia

<p>Mentigi Gunung (<em>Vaccinium varingiaefolium</em> (Blume) Miq.), endemic plant of Java which dominates sub-alpine area of Mount Batok. This study aimed to characterize plant’s anatomical and morphological structure for conservation purpose. Microscopic and macroscopic approaches used for organs observation. Morphological observation showed that this plant has a tap root, circular stem with lenticels on its surface. It has red young stem with a lot of trichomes, brown old stem, oval leaves with integer margins. Leaves have stone cells, cuticles, idioblasts. Young leaves are red and turn green. Flowers are purple with five sepals, five petals, 10 androecium and one syncarp gynoecium. Trichomes spread all over flower structures. The type of microspore is tetraeder. The gynoecium sits on the receptacle composed of five carpellum with inpherus ovulus. The fruits are green, globular, with trichomes and turn black when ripe. It has stone cells with purple cytoplasm and golden brown seeds. Vascular bundle is opened collateral type; the type is parasitic with kidney-shaped guard cells.</p><div><p class="Els-keywords"><strong>Keywords:</strong> Anatomy; morphology; mentigi gunung; <em>Vaccinium varingiaefolium</em> (Blume) Miq.</p></div>

Dual roles for bone marrow-derived Sca-1 cells in cardiac function.

Recruitment of stem cells from the bone marrow (BM) is an important aspect of cardiac healing that becomes inefficient with age. We investigated the role of young stem cell antigen 1 (Sca-1)-positive BM cells on the aged heart by microarray analysis after BM reconstitution. Sca-1+ and Sca-1- BM cells from young green fluorescent protein (GFP)-positive mice were used to reconstitute the BM of aged mice. Myocardial infarction (MI) was induced 3 mo later. GFP+ cells were more abundant in the BM, blood, and heart of Sca-1+ mice, which corresponded to preserved cardiac function after MI. At baseline, Sca-1+ BM reconstitution increased cardiac expression of serum response factor, vascular endothelial growth factor A, and myogenic genes, but reduced the expression of Il-1β. After MI, inflammation was identified as a key difference between Sca-1- and Sca-1+ groups, as cytokine expression and cell surface markers associated with inflammatory cells were up-regulated with Sca-1+ reconstitution. Mac-3 and F4/80 staining showed that the postinfarction heart was composed of a mixture of GFP+ (donor) macrophages, GFP- (host) macrophages, and GFP+ cells that did not contribute to the macrophage population. This study demonstrates that Sca-1+ BM cells regulate cardiac healing though an acute inflammatory response and also before injury by stimulating formation of a beneficial cardiac niche.-Tobin, S. W., Li, S.-H., Li, J., Wu, J., Yeganeh, A., Yu, P., Weisel, R. D., Li, R.-K. Dual roles for bone marrow-derived Sca-1 cells in cardiac function.

Written in bone: young bone makes young blood.

Ageing of bone marrow haematopoietic stem cells has been mostly associated with cell‐intrinsic mechanisms. New findings published in The EMBO Journal now show that reduced levels of the secreted matrix protein osteopontin in old bone marrow stroma cause ageing‐associated features in HSCs. In line, old HSCs are functionally rejuvenated by interaction with protease‐cleaved osteopontin fragment, and perform like young blood stem cells in vivo .

Micromorphology of stem surface in three species of Bambusa (Poaceae, Bambusoideae) with a focus on its impact on plant-insect interactions

The aim of this study was to analyse the microstructure of the young stem (culm) surface in tree bamboo species of the genus Bambusa (B. chungii, B. emeiensis and B. multiplex). We examined the outermost layers of culm sheaths and internodes using scanning electron microscopy. The species studied show differences in the presence of trichomes and waxes on sheaths and internodes: only trichomes on sheaths of B. emeiensis, only 3-dimensional epicuticular wax coverage on internodes of B. chungii and sheaths of B. multiplex, and a combination of trichomes and waxes on sheaths of B. chungii and internodes of B. multiplex. Trichomes in all three species studied are of the same type (non-glandular, non-branched) with a similar structure (unicellular, hollow inside, with thin wall) and shape, but have different dimensions. The epicuticular wax coverage in both B. chungii and B. multiplex are composed of longitudinally aggregated rodlets. The degree of coiling and dimensions of the aggregates as well as diameter of the terete rodlets, their number in rows, and the number of rows in aggregates differ among the species. The contribution of trichomes and the epicuticular wax coverage to the plant protective function against insects is discussed. Hairy and waxy stem surfaces, hampering the access of ants to aphid colonies via reducing ant attachment ability, represent the phenomenon called stem guard syndrome.

Autophagy maintains the metabolism and function of young and old stem cells.

With age, hematopoietic stem cells (HSCs) lose their ability to regenerate the blood system, and promote disease development. Autophagy is associated with health and longevity, and is critical for protecting HSCs from metabolic stress. Here, we show that loss of autophagy in HSCs causes accumulation of mitochondria and an activated metabolic state, which drives accelerated myeloid differentiation mainly through epigenetic deregulations, and impairs HSC self-renewal activity and regenerative potential. Strikingly, the majority of HSCs in aged mice share these altered metabolic and functional features. However, ~ 1/3 of aged HSCs exhibit high autophagy levels and maintain a low metabolic state with robust long-term regeneration potential similar to healthy young HSCs. Our results demonstrate that autophagy actively suppresses HSC metabolism by clearing active, healthy mitochondria to maintain quiescence and stemness, and becomes increasingly necessary with age to preserve the regenerative capacity of old HSCs.

Stoichiometric variation of halophytes in response to changes in soil salinity.

Variation in soil salt may change the stoichiometry of a halophyte by altering plant ecophysiology, and exert different influences on various plant organs, which has potentially important consequences for the nutrition of consumers as well as nutrient cycling in a saline ecosystem. Using a greenhouse pot experiment, we investigated the effect of salinity variability on the growth and stoichiometry of different organs of Suaeda glauca and Salicornia europaea - two dominant species of important ecological and economic value in the saline ecosystem. Our results showed that appropriate salt stimulated the growth of both species during the vigorous growth period, while high salt suppressed growth. Na significantly increased with increased salt in the culture, whereas concentrations of other measured elements and K:Na ratio for both species significantly decreased at low salt treatments, and became more gradual under higher salt conditions. Furthermore, with the change of salt in culture, variations in leaf (degenerated leaf for S.europaea, considered as young stem) stoichiometry, except N:P ratio, were large and less in stems (old stems for S.europaea) than in roots, reflecting physiological and biochemical reactions in the leaf in response to salt stress, supported by sharp changes in trends. These results suggest that appropriate saline conditions can enhance biological C fixation of halophytes; however, increasing salt could affect consumer health and decrease cycling of other nutrients in saline ecosystems.

Hormone Distribution and Transcriptome Profiles in Bamboo Shoots Provide Insights on Bamboo Stem Emergence and Growth.

Growth and development are tightly co-ordinated events in the lifetime of living organisms. In temperate bamboo plants, spring is the season when environmental conditions are suitable for the emergence of new shoots. Previous studies demonstrated that bamboo plants undergo an energy-consuming 'fast stem growth' phase. However, the events during the initiation of stem elongation in bamboo are poorly understood. To understand the onset of bamboo stem growth, we performed hormone and transcriptome profiling of tissue regions in newly elongating shoots of the Moso bamboo Phyllostachys edulis. The growth hormones auxins, cytokinins and gibberellins accumulated in the shoot apex, while the stress hormones ABA, salicylic acid (SA) and jasmonic acid (JA) are predominantly found in the lower part of the stem. The mature basal part of the stem showed enrichment of transcripts associated with cell wall metabolism and biosynthesis of phenylpropanoid metabolites, such as lignin. In the young upper stem region, expression of cell formation- and DNA synthesis-related genes was enriched. Moreover, the apical region showed enhanced expression of genes involved in meristem maintenance, leaf differentiation and development, abaxial/adaxial polarity and flowering. Our findings integrate the spatial regulation of hormones and transcriptome programs during the initiation of bamboo stem growth.

Social group membership increases STEM engagement among preschoolers.

The American educational system currently yields disappointing levels of science, technology, engineering, and math (STEM) engagement and achievement among students. One way to remedy this may be to increase children's motivation in STEM from an early age. This study examined whether a social cue-being part of an experimental "minimal group"-increases STEM engagement in preschoolers (N = 141; 4.5-year-olds). Using a within-subjects design, participants were assigned to a group and an individual condition (counterbalanced for order) before they worked on a math task and a spatial task. Children persisted longer on, placed more pieces correctly, reported higher self-efficacy, and were more interested in the group STEM task than the individual STEM task. In addition, we conducted a continuously cumulating meta-analysis (CCMA) to combine the results of the current experiment with two previous experiments. These findings suggest that incorporating nonacademic social factors, such as group membership, into current STEM curricula could be an effective way to boost young children's STEM motivation. (PsycINFO Database Record

Human umbilical cord-derived mesenchymal stromal cells protect against premature renal senescence resulting from oxidative stress in rats with acute kidney injury

BackgroundMesenchymal stromal cells (MSCs) represent an option for the treatment of acute kidney injury (AKI). It is known that young stem cells are better than are aged stem cells at reducing the incidence of the senescent phenotype in the kidneys. The objective of this study was to determine whether AKI leads to premature, stress-induced senescence, as well as whether human umbilical cord-derived MSCs (huMSCs) can prevent ischaemia/reperfusion injury (IRI)-induced renal senescence in rats.MethodsBy clamping both renal arteries for 45 min, we induced IRI in male rats. Six hours later, some rats received 1 × 106 huMSCs or human adipose-derived MSCs (aMSCs) intraperitoneally. Rats were euthanised and studied on post-IRI days 2, 7 and 49.ResultsOn post-IRI day 2, the kidneys of huMSC-treated rats showed improved glomerular filtration, better tubular function and higher expression of aquaporin 2, as well as less macrophage infiltration. Senescence-related proteins (β-galactosidase, p21Waf1/Cip1, p16INK4a and transforming growth factor beta 1) and microRNAs (miR-29a and miR-34a) were overexpressed after IRI and subsequently downregulated by the treatment. The IRI-induced pro-oxidative state and reduction in Klotho expression were both reversed by the treatment. In comparison with huMSC treatment, the treatment with aMSCs improved renal function to a lesser degree, as well as resulting in a less pronounced increase in the renal expression of Klotho and manganese superoxide dismutase. Treatment with huMSCs ameliorated long-term kidney function after IRI, minimised renal fibrosis, decreased β-galactosidase expression and increased the expression of Klotho.ConclusionsOur data demonstrate that huMSCs attenuate the inflammatory and oxidative stress responses occurring in AKI, as well as reducing the expression of senescence-related proteins and microRNAs. Our findings broaden perspectives for the treatment of AKI.

Dynamic adhesive environment alters the differentiation potential of young and ageing mesenchymal stem cells

Dynamic adhesive environment alters the differentiation potential of young and ageing mesenchymal stem cells

Pharmacognostic Assesment of the Endemic and Vulnerable Medicinal Climber-Cayratia pedata (Lam.) Gagnep. var. glabra Gamble and Its Antibacterial Activity.

Objective:The objective of this study is to evaluate a meticulous pharmacognostic cram is to supplement constructive information with regard to its identification, characterization, and standardization of endemic and endangered medicinal climber Cayratia pedata var. glabra and also screening the antibacterial activity of this climber.Materials and Methods:The morphological characters of study plant, microscopic examination of leaf powder, anatomy of young stem, physicochemical analysis of plant powder, extractive values, phytochemical analysis, powder with different chemical reagents, fluorescence analysis of plant powder, and other World Health Organization (WHO) recommended for standardization were analyzed. The antibacterial activity of this study plant is also analyzed.Results:C. pedata var. glabra belongs to the family Vitaceae, commonly known as “Kattuppirandai” is one such endemic and endangered species in Thaisholai, Nilgiris South Division, Western Ghats. With the patronage of veteran ethnic group traditional knowledge of this region, the species C. pedata var. glabra was selected for the pharmacognostical examination and antibacterial screening. There were no pharmacognostical reports of this plant, specifically to determine the anatomical and other physicochemical standards required for its quality control. The current study deals with pharmacognostical parameters for the aerial parts of study plant, which mainly consists of macromorphological and microanatomical characters, physicochemical constants (ash values and extractive values), fluorescence analysis, and phytochemical screening, one of the WHO accepted parameter for the identification of medicinal plants. The pharmacognostical exploration was undertaken for this species with the purpose of sketch the pharmacopeial standards. The antibacterial activity of this plant confirms the therapeutic power.Conclusion:The information obtained from pharmacognostical studies will be of used for supplementary pharmacological and therapeutical evaluation of the species and will assist in standardization for quality, purity, and authentication with the help, of which adulteration and substitution can be prevented. The antibacterial activity of this plant confirm the traditional knowledge of local healers on the wound healing property of this species and also suggest this plant species can be used as a promising source for the development of new pharmaceuticals that address the therapeutic needs to cure infectious diseases.SUMMARY The species C. pedata var. glabra was selected for present research work, since this species is listed in Red data book and has a wider use for different ailments among the tribal population of Thiashola due to its high medicinal value. Pharmacognostical profile was generated from macroscopical analysis, microscopical studies, powder analysis, physico-chemical constituent values, fluorescence analysis and preliminary phytochemical evaluation. The antibacterial activity of this plant confirms the therapeutic power. Abbreviations Used: WHO: World Health Organization; IUCN: International Union for the Conservation of Nature.

Tissue-Specific Expression Profiling of Seedling Stage in Early-Maturity Mutant Induced by Carbon Ion Beam in Sweet Sorghum

<p class="MDPI17abstract">An early-maturity mutant KFJT-1 has been screened out after carbon ion irradiation in sweet sorghum (<em>Sorghum bicolor</em> (L.) Moench). In this study, tissue specific digital gene expression analysis was performed between the KFJT-1 mutant and the wild type KFJT-CK at seedling stage. The results showed that a total of 717, 2160 and 2,331 tags-mapped genes were differently expressed in roots, stems and leaves of young seedling, respectively. In KFJT-1, 557 (77.7%) genes were up-regulated and 160 (22.3%) genes were down-regulated in young root; 1,232 (57.0%) genes were up-regulated and 928 (43.0%) were down-regulated in young stem; and 1,577 (67.7%) genes were up-regulated and 754 (32.3%) genes were down-regulated in young leaf. Functional annotation revealed that most induced genes functioned as “binding”, “synthase activity”, “transferase” and “transporter activity” which involved in the biological processes of metabolic and response to stimulus. Surprisingly, the up-regulated genes in KFJT-1 were classified into four KEGG pathways: “alpha-Linolenic acid metabolism”, “flavonoid biosynthesis”, “inositol phosphate metabolism” and “fatty acid biosynthesis”, which related to the stress resistance and supported the outstanding agronomic traits of KFJT-1 in the process of plant growth and development. Among the DEGs, a critical photoreceptor from photoperiod pathway <em>PHYA</em> gene was significantly up-regulated in leaf and root of KFJT-1, suggesting the mutation could occur on the genomic upstream of <em>PHYA</em>. This work may provide helpful insights to further understand the mutation mechanism in sweet sorghum.</p>

Hematopoietic Stem Cells Respond Heterogeneously to Inflammatory Signals in an Age-Dependent Manner

Hematopoietic stem cells (HSCs) have the unique responsibility to produce balanced immune cell output throughout an organism's life. Importantly, they must do so robustly despite a plethora of external stress, including frequent inflammatory challenge. With age, the accumulation of these stresses leads to impaired HSC function and myeloid-biased output. Aged HSCs are also more prone to pathological hematopoiesis, such as myeloproliferative disorder, leukemia and autoimmune diseases. However, little is known about the subcellular mechanisms that govern the inflammatory response of HSCs with age, which in turn might contribute to pathologic transformation.We show that young hematopoietic stem and progenitor cells (HSPCs) demonstrate a robust transcriptional response to toll-like receptor (TLR) ligands. Interestingly, this response is similar to that of mature immune cell types such as dendritic cells. Using single-cell proteomic assays, we found that young HSPCs secrete a diverse array of myeloid and lymphoid cytokines. However, when challenged with TLR ligands in vivo, young mice acutely increase myeloid-biased output but return rapidly to baseline hematopoietic output of both lymphoid and myeloid cells. Moreover, inflammatory challenge of young long-term HSCs in vitro did not perturb the function and output of these cells in bone marrow reconstitution experiments.In contrast to their counterparts from young mice, we found HSPCs obtained from aged mice have a diminished ability to secrete cytokines in response to TLR ligands. Furthermore, they secrete a homogenous subset of myeloid-biased cytokines. When challenged with TLR ligands in vivo, aged mice acutely increased myeloid output and maintain elevated myeloid output for several months implying memory of the inflammatory challenge. Consistent with this, we also found that pre-stimulation of aged HSCs prior to bone marrow transplant results in a sustained increase in myeloid output compared to unstimulated aged HSCs.To elucidate the differential heterogeneity between young and aged HSPCs in response to TLR signaling, we next performed single-cell RNA sequencing (RNA-seq) experiments. We found that the sustained myeloid output in aged mice after TLR stimulation is largely due to expansion of a myeloid-biased HSC subset in the aged HSC pool. By characterizing the gene expression networks that define these myeloid-biased HSCs under stimulation conditions, we were then able to identify a myeloid-biased HSC subset in both the unperturbed young and aged HSC pools. Moreover, we found that these cells are more abundant in aged mice at steady-state, and that these HSCs demonstrate a unique response to inflammatory challenge. We further identify putative transcriptional regulators, including Klf4, Klf5, Ikzf1 and Stat3, among others, that define gene expression in these myeloid-biased HSCs. We further show that loss of function of these factors can differentially alter myeloid output in young and aged mice both in vitro and in vivo.Our results demonstrate that there is a differential response of young and aged HSCs to inflammatory signals. Using single-cell RNA-seq and protein secretion studies, we elucidate the molecular heterogeneity of the HSC pool at steady state and with TLR stimulation. By resolving heterogeneous subsets of cells in both the young and aged HSC pool, and by uncovering the transcriptional regulators that influence their function, we thus propose a new model of inflammatory hematopoiesis that may have implications to understanding age-related defects in immune development. DisclosuresNo relevant conflicts of interest to declare.

Propagation pattern of Machaerium Lunatum (Linn F) ducke in five different soil types

Machaerium lunatum is a perennial shrub that grows in aquatic environment especially on the banks of fresh, brackish and marine habitats especially in tidal zones. A study of the possibility of the propagation of this plant outside its natural aquatic environment, what part of the stem will grow and what soil type will be most suitable for it was carried out. Mature, medium and very young stem propagules and five soil types were used for this purpose and include (a) riverbed soil, from the natural habitat of the plant, (b) sandy soil, (c) clay soil, (d) Humus soil and (e) a mixture of sandy + Humus soil. The study was carried out for five weeks at the University of Port Harcourt Ecological Centre. The parameters used to measure the performance were plant height, leaf number, leaf area, and the number of sprouted nodes. At the end of the study, it was found that humus soil had the highest figure for plant height (4.6±1.14) closely followed by riverbed soil (4.5±2.4). For number of leaves riverbed soil performed better than the other soil types (19.1± 7.1). Sandy soil performed better than others (1.5±0.3) for leaf area while for sprouted node Humus soil was higher (1.75± 0.8) than the others. This result shows that M. lunatum can be propagated outside its natural environment, and humus soil can support the growth better than the other soil types. This study will also provide a template for further studies on this plant since its importance in the Niger Delta cannot be overemphasized. Keywords: Machaerium lunatum , Propagation, Humus soil, River-bed soil, Sandy soil, Aquatic environment

A Prospective Study of Alemtuzumab as a Second-Line Agent for Steroid-Refractory Acute Graft-versus-Host Disease in Pediatric and Young Adult Allogeneic Hematopoietic Stem Cell Transplantation

We describe a single-center prospective study of alemtuzumab as a second-line agent for steroid-refractory (SR) acute graft-versus-host disease (aGVHD) in pediatric and young adult allogeneic hematopoietic stem cell transplant recipients. Alemtuzumab was administered for grades II to IV aGVHD if patients did not improve within 5 days or worsened within 48 hours after corticosteroids. Interim analyses of alemtuzumab levels and response were performed after every 5 patients enrolled, resulting in 3 dosing cohorts, as follows: (1) .2 mg/kg alemtuzumab subcutaneously on days 1 to 5 (maximum of 31 mg over 5 days) and .2 mg/kg/dose (not exceeding 10 mg/dose) on days 15, 22, and 29; (2) .2 mg/kg alemtuzumab subcutaneously on days 1 to 5 (maximum of 43 mg over 5 days) and .2 mg/kg/dose on day 7, 10, 15, 22, and 29; and (3) .2 mg/kg subcutaneously on days 1 to 5 and .2 mg/kg/dose on day 7, 10, 15, and 22. Alemtuzumab levels were assessed before starting alemtuzumab and at days 1, 3, 6, 10, and 14 and weekly until day 99, where day 1 was the day of first alemtuzumab dose. Fifteen patients (median age, 10 years; range, 1.4 to 27) received alemtuzumab for grades II (6%), III (74%), and IV (20%) SR-aGVHD. The overall response rate was 67%, with complete response (CR) in 40%, partial response (PR) in 27%, and no response in 33%. The median day 6 alemtuzumab level was 2.79 µg/mL (interquartile range, 1.34 to 4.89) in patients with CR compared with .62 µg/mL (interquartile range, .25 to 1.45) in patients with PR + no response (P < .05). Ninety percent (n = 9) of patients with a CR or PR reduced corticosteroid doses within 8 weeks from first alemtuzumab dose. Side effects included fever (26%) and transient thrombocytopenia (53%). Asymptomatic viremias occurred in all patients but invasive viral disease occurred in 2 patients. One patient developed Epstein-Barr virus–post-transplantation lymphoproliferative disorder. Eighty percent (n = 12) of patients were alive at 6 months, of whom 53% (n = 8) were free of GVHD whereas 13% (n = 2) developed chronic GVHD. Alemtuzumab is an effective second-line agent for children and young adults with SR-aGVHD. Higher alemtuzumab levels are associated with CR. A real-time dose adjusted alemtuzumab study is needed to further optimize the dose of alemtuzumab in aGVHD.

English

MYB transcription factors in plant play a critical role in regulating response to abiotic stress or adverse environments. In our previous study, DGEP data revealed GmMYB92 is involved in soybean tolerance to abiotic stress. Here, we analyzed the spatial and temporal expression of GmMYB92 and found GmMYB92 mainly expressed in roots, young stem and flower tissues during the whole growth stages, and significantly induced by ABA, salt, low temperature (4°C) and PEG6000 (drought) treatments, and the time points for induction expression varied among different treatments. Bioinformatic analysis of GmMYB92 promoter region contained many stress-related cis-elements, such as, HSE for heat stress, ARE for anaerobic induction, TC-rich repeat element for defense and stress responsiveness and a CAT-box for specific-expression element in meristem expression. Hereafter, the GmMYB92 promoter region with a 1,951bp DNA fragment including start codon was cloned to drive GUS gene expression to form a chimeric expression cassette used for Arabidopsis Thaliana transformation by means of floral dip. GUS histochemical staining was conducted to characterize the GmMYB92 promoter activity in different tissues including root, stem, leaf, flower and pod from transgenic Arabidopsis Thaliana. The results showed that the gus gene under the control of GmMYB92 promoter mainly expressed in root, young stem and flower, which was consistent with the expression pattern in soybean plant. Our study supply a basis support to further insight into MYB transcription factor’s role in the complicated regulation network related to different genes and the mechanism in stress-resistance in plants.

Estructura de bosques de pino pátula bajo manejo en Ixtlán de Juárez, Oaxaca, México

Se evaluó y comparó la diversidad de especies arbóreas y la composición estructural de bosques de pino pátula (Pinus patula Schl et Cham) bajo diferentes condiciones silvícolas, en Ixtlán de Juárez, Oaxaca, México. Se registró información sólo para ejemplares mayores de 7,5 cm de diámetro normal. La diversidad se estimó a través del Índice Shannon (H’), la composición estructural se definió mediante tres características, mezcla de especies, distribución espacial y diferenciación de tamaños, a través de los índices, Mezcla de Gadow (Mi), Uniformidad de Ángulos (Wi) y Dominancia (Ui), respectivamente. El análisis se realizó comparando cuatro condiciones silvícolas denominadas, latizal, fustal joven, fustal medio y fustal viejo. Los resultados mostraron que la mayor diversidad arbórea se presentó en los bosques fustal medio y fustal viejo. El mayor grado de mezcla se presentó en la condición fustal viejo. La distribución del arbolado en el terreno, en los cuatro ambientes, presentó un patrón de distribución aleatorio y la dominancia de pino pátula va en aumento conforme la condición se desarrolla.

RNA Splicing Modulation Selectively Impairs Leukemia Stem Cell Maintenance in Secondary Human AML

Age-related human hematopoietic stem cell (HSC) exhaustion and myeloid-lineage skewing promote oncogenic transformation of hematopoietic progenitor cells into therapy-resistant leukemia stem cells (LSCs) in secondary acute myeloid leukemia (AML). While acquisition of clonal DNA mutations has been linked to increased rates of secondary AML for individuals older than 60 years, the contribution of RNA processing alterations to human hematopoietic stem and progenitor aging and LSC generation remains unclear. Comprehensive RNA sequencing and splice-isoform-specific PCR uncovered characteristic RNA splice isoform expression patterns that distinguished normal young and aged human stem and progenitor cells (HSPCs) from malignant myelodysplastic syndrome (MDS) and AML progenitors. Insplicing reporter assays and pre-clinical patient-derived AMLmodels, treatment with a pharmacologic splicing modulator, 17S-FD-895, reversed pro-survival splice isoform switching and significantly impaired LSC maintenance. Therapeutic splicing modulation, together with monitoring splice isoform biomarkers of healthy HSPC aging versus LSC generation, may be employed safely and effectively to prevent relapse, the leading cause of leukemia-related mortality.

Cell Wall Heterogeneity in Root Development of Arabidopsis.

Plant cell walls provide stability and protection to plant cells. During growth and development the composition of cell walls changes, but provides enough strength to withstand the turgor of the cells. Hence, cell walls are highly flexible and diverse in nature. These characteristics are important during root growth, as plant roots consist of radial patterns of cells that have diverse functions and that are at different developmental stages along the growth axis. Young stem cell daughters undergo a series of rapid cell divisions, during which new cell walls are formed that are highly dynamic, and that support rapid anisotropic cell expansion. Once the cells have differentiated, the walls of specific cell types need to comply with and support different cell functions. For example, a newly formed root hair needs to be able to break through the surrounding soil, while endodermal cells modify their walls at distinct positions to form Casparian strips between them. Hence, the cell walls are modified and rebuilt while cells transit through different developmental stages. In addition, the cell walls of roots readjust to their environment to support growth and to maximize nutrient uptake. Many of these modifications are likely driven by different developmental and stress signaling pathways. However, our understanding of how such pathways affect cell wall modifications and what enzymes are involved remain largely unknown. In this review we aim to compile data linking cell wall content and re-modeling to developmental stages of root cells, and dissect how root cell walls respond to certain environmental changes.