Permanent Tissues Research Articles

Comparative proteomic analysis of dental pulp from supernumerary and normal permanent teeth

ObjectivesTo obtain and compare the protein profiles of supernumerary and normal permanent dental pulp tissues.Materials and methodsDental pulp tissues were obtained from supernumerary and normal permanent teeth. Proteins were extracted and analyzed by liquid chromatography-tandem mass spectrometry (LC/MS-MS). Protein identification and quantification from MS data was performed with MaxQuant. Statistical analysis was conducted using Metaboanalyst to identify differentially expressed proteins (DEPs) (P-value < 0.05, fold-change > 2). Gene Ontology enrichment analyses were performed with gProfiler.ResultsA total of 3,534 proteins were found in normal dental pulp tissue and 1,093 in supernumerary dental pulp tissue, with 174 DEPs between the two groups. This analysis revealed similar functional characteristics in terms of cellular component organization, cell differentiation, developmental process, and response to stimulus, alongside exclusive functions unique to normal permanent dental pulp tissues such as healing, vascular development and cell death. Upon examination of DEPs, these proteins were associated with the processes of wound healing and apoptosis.ConclusionsThis study provides a comprehensive understanding of the protein profile of dental pulp tissue, including the first such profiling of supernumerary permanent dental pulp. There are functional differences between the proteomic profiles of supernumerary and normal permanent dental pulp tissue, despite certain biological similarities between the two groups. Differences in protein expression were identified, and the identified DEPs were linked to the healing and apoptosis processes.Clinical relevanceThis discovery enhances our knowledge of supernumerary and normal permanent pulp tissue, and serves as a valuable reference for future studies on supernumerary teeth.

Cortisol in deciduous tooth tissues: A potential metric for assessing stress exposure in archaeological and living populations

ObjectiveCortisol is a glucocorticoid hormone produced by the hypothalamic-pituitary-adrenal axis that is regularly assessed in modern human and non-human populations in saliva, blood, and hair as a measure of stress exposure and stress reactivity. While recent research has detected cortisol concentrations in modern and archaeological permanent dental tissues, the present study assessed human primary (deciduous) teeth for cortisol concentrations. Materials and MethodsFifty-one dentine and enamel samples from nine modern and 10 archaeological deciduous teeth were analyzed for cortisol concentrations via enzyme-linked immunosorbent assay (ELISA). ResultsDetectable concentrations of cortisol were identified in 15 (of 32) dentine and 8 (of 19) enamel samples coming from modern and archaeological deciduous teeth. ConclusionsThis study is the first known analysis of cortisol from deciduous dental tissues, demonstrating the potential to identify measurable concentrations. SignificanceThe ability to analyze deciduous teeth is integral to developing dental cortisol methods with multiple potential future applications, including research on the biological embedding of stress in the skeleton. This study marks a key step in a larger research program to study stress in primary dentition from living and archaeological populations. LimitationsMultiple samples generated cortisol values that were not detectable with ELISA. Minimum quantities of tissue may be required to generate detectable levels of cortisol. Suggestions for Further ResearchFuture research should include larger sample sizes and consideration of intrinsic biological and extrinsic preservation factors on dental cortisol. Further method validation and alternative methods for assessing dental cortisol are needed.

Alveólise em elementos decíduos associada com traumatismo dentário: Relato de caso

A alveólise é caracterizada como a reabsorção da tábua óssea alveolar com subsequente exposição da raiz do dente decíduo na cavidade bucal. Apresenta etiologia não esclarecida, apesar de frequentemente estar associada com infecções decorrentes de cárie e o traumatismo dentário. Objetivou-se neste estudo relatar um caso clínico de uma paciente de 6 anos de idade, sexo feminino, que compareceu a Unidade Básica de Saúde de uma cidade no interior da Paraíba, com alveólise após trauma dentário. Ao exame clínico observou-se a presença de alveólise nos elementos 51 e 52, lesão que foi marcada pela mobilidade dos elementos dentários e extensa lesão gengival no sentindo vertical, inciso-apical, na região vestibular (51). A raiz do elemento 51 apresentava-se exposta sem a proteção do osso alveolar e da mucosa e a do 52 com exposição da região apical. O tratamento indicado foi a exodontia dos elementos supracitados e acompanhamento clínico dos demais. A conduta clínica foi iniciada com uma adaptação psicológica da paciente, pois esta tivera sofrido um trauma e sentia dor na região. O protocolo clínico foi a anestesia tópica da região; anestesia terminal infiltrativa; sindesmotomia, luxação e exérese. Conclui-se que tratando-se de uma emergência odontológica é necessário a remoção de dentes decíduos com alveólise evitando-se lesões nos dentes permanentes subsequentes e tecidos moles adjacentes. O acompanhamento clínico dos demais elementos é de fundamental importância. A odontopediatria necessita de mais relatos de caso nessa temática para que a etiologia e conduta clínica possam seguir os preceitos da odontologia baseada em evidências.

Radiation diagnostics of cervical invasive resorption and treatment planning according to cone beam computed tomography

Resorption of permanent tooth tissues is always a patho-logical process, the cause of which is not known, and an asymptomatic course in the early stages makes it difficult to diagnose. The pathogenesis of the disease and clini-cal and radiological prisms have been studied, as well as the main predisposing factors for the occurrence of re-sorption are known. Objective: timely detection of the disease by doctors in dental patients remains relevant. The purpose of this study is to find the possibility of early and accurate diagnosis of cervical invasive dental resorp-tion and to plan treatment based on the obtained data of targeted cone-beam computed tomography. Mate-rial and metods: data from outpatient records of dental patients with detected dental resorption. We analyzed cases of cervical invasive resorption in 67 patients. When applying, patients complained about the condition of the causal tooth with diagnosed resorption only in isolated cases, and the diagnosis was made according to compu-ter tomography. Cone beam computed tomography was also the only method that allowed determining the entry point of cervical and invasive resorption, and with this in mind, planning the location of the dosupa for treatment. Diagnostics of resorption is based mainly on x-ray me-thods, and mainly on cone-beam computed tomography (CBCT) data. Results: complaints about teeth related to resorption were made by only 11.9% of patients out of the total number of people who were diagnosed with cervical invasive resorption. Complaints related to issues of various discomfort due to the presence of defects, dis-coloritis of the teeth, pain in the area of the causal tooth was indicated by 2 people. 67.2% of patients were diag-nosed with various clinical forms of periodontitis. 26.9% are undergoing or were undergoing orthodontic treat-ment. 7.5% of the subjects had a history of dental trauma. The average age: in the group of men was 39.4 years, in women — 42.9 years. The entry point of cervical invasive resorption was most often determined in the incisors and canines of the upper and lower jaw. The localization of the entry point was most often determined on the ves-tibular surface of the teeth in 31.1%, on the oral surface in 35.6%, on the approximal surfaces in 26.7%. the Asymp-tomatic course of CIR suggests the priority of using mo-dern methods of full-fledged informative high-tech x-ray examination of dental patients, in particular, CLCT. The ability to determine the localization of the resorption en-try point according to CLCT data, allows you to plan sur-gery for treatment. Conclusion: the developed standard for examination of patients using cone-beam computed tomography makes it possible to diagnose early cervical invasive resorption when drawing up a treatment plan for a primary patient and in all cases planning primary or re-peated endodontic treatment.

How Water Can Affect Keratin: Hydration‐Driven Recovery of Bighorn Sheep (Ovis Canadensis) Horns

AbstractKeratin is one of the most common structural biopolymers exhibiting high strength, toughness, and low density. It is found in various tissues such as hairs, feathers, horns, and hooves with various functionalities. For instance, horn keratin absorbs a large amount of energy during intraspecific fights. Keratinized tissues are permanent tissues because of their basic composition consisting of dead keratinized cells that are not able to remodel or regrow once broken or damaged. The lack of a self‐healing mechanism presents a problem for horns, as they are under continued high risk from mechanical damage. In the present work, it is shown for the first time that a combination of material architecture and a water‐assisted recovery mechanism, in the horn of bighorn sheep, endows them with shape and mechanical property recoverability after being subjected to severe compressive loading. Moreover, the effect of hydration is unraveled, on the material molecular structure and mechanical behavior, by means of synchrotron wide angle X‐ray diffraction, Fourier transform infrared spectroscopy, nanoindentation, and in situ and ex situ tensile tests. The recovery and remodeling mechanism is anisotropic and quite distinct to the self‐healing of living tissue such as bones.

Membrane proteome characterization of periodontal ligament cell sets from deciduous and permanent teeth.

Physiological roles for the periodontal ligament (PDL) include tooth eruption and anchorage, force absorption, and provision of proprioceptive information. Despite the advances in understanding the biology of PDL cells, there is a lack of information regarding the molecular signature of deciduous (DecPDL) and permanent (PermPDL) PDL tissues. Thus, the present study was designed to characterize the membrane proteome of DecPDL and PermPDL cells. Primary PDL cells were obtained (n=6) and a label-free quantitative proteome of cell membrane-enriched components was performed. Proteome findings were validated by quantitative polymerase chain reaction and Western blot assays in fresh human tissues (n=8) and primary cell cultures (n=6). In addition, confocal microscopy was used to verify the expression of target factors in the PDL cell cultures. Comparative gene ontology enrichment analysis evidenced that most stickling differences involved "endomembrane system" (PICALM, STX4, and LRP10), "hydrolase activity" (NCSTN and XRCC6), "protein binding" (PICALM, STX4, GPNMB, VASP, extended-synaptotagmin 2 [ESYT2], and leucine-rich repeat containing 15 [LRRC15]), and "isomerase activity" (FKBP8). Data are available via ProteomeXchange with identifier PXD010226. At the transcript level, high PICALM in DecPDL and ESYT2 and LRRC15 in PermPDL were confirmed in fresh PDL tissues. Furthermore, Western blot analysis confirmed increased levels of PICALM, LRRC15, and ESYT2 in cells and/or fresh tissues, and confocal microscopy confirmed the trends for PICALM and LRRC15 expression in PDL cells. We report the first comprehensive characterization of the membrane protein machinery of DecPDL and PermPDL cells, and together, we identified a distinct molecular signature for these cell populations, including unique proteins for DecPDL and PermPDL.

Histochemical Study of Xylem Cells in In Vitro Culture of Iris sibirica L.

In this study, lignin content data are presented for annual regenerant Iris sibirica plants, comparable to those in six-year-old intact plants. The structure of the shoots of Iris sibirica grown on artificial nutrient media was studied by the histochemical method. Features of the formation of the xylem in Iris sibirica on artificial nutrient media were revealed. Regenerants very quickly developed a complex system consisting of vascular bundles containing sieve tubes, vessels and tracheids, and hydrocyte systems. Hydrocytes of Iris sibirica were tracheids with lignified thickening, but, in contrast to tracheids and vessels of xylem (they are formed based on procambium or cambium—special lateral primary or secondary meristem), hydrocytes differentiated from the cells of permanent tissues (like phellogen), which probably possessed meristematic activity at the time of differentiation. In Iris sibirica hydrocytes covered the vascular bundle by the thick layer and strung along it up to a certain height. High lignin content in young regenerant Iris sibirica plants was due to the formation of the dense tissue from lignified tracheal elements. The study of the differentiation of xylem elements under controlled conditions can serve as a model for our understanding of wood formation processes.

Signal transduction growth factors: the effective governance of transcription and cellular adhesion in cancer invasion

Giulio Bizzozero classified the tissues concerning their capacity to self-renew during the adult life in labile, stable and permanent tissues. In 1940 Viktor Hamburger and Rita Levi Montalcini exposed the possibility to induce the growth of permanent cells thanks to a specific ligand Nerve Growth Factor (NGF). Stanley Cohen purified a protein the Epidermal Growth Factor (EGF), able to induce epidermis proliferation and to elicit precocious eye disclosure and teeth eruption, establishing the “inverse” relationships between the proliferation and differentiation. These two biological effects induced by EGF were according to EGFR signaling is involved in a large array of cellular functions such as proliferation, survival, adhesion, migration and differentiation. This review is focused on the key role of growth factors signaling and their downstream effectors in physiological and in pathological phenomena, the authors highlight the governance of Growth factors during the EMT in cancer invasion.

Morphological Characterization of Buds Being Donors of Apex for Molecular Confirmation of Differentiation of Meristem into Permanent Tissues of Stone Fruit Trees (Prunus sp.)

Molecular confirmation of the process of differentiation of meristematic tissue of plants is primarily based on histomorphological characterization of the tissues carrying these processes. For perennial plants – fruit trees, the knowledge of these processes is important to define runtime type and pomotechnical treatments but also to identify the genes responsible for determination of the apices into a generative phase of differentiation. Which apex extraction techniques will be applied depends on the structure of buds, i.e. whether an apex differentiates only into generative elements – pure flower buds, or the differentiation goes into two directions: differentiation of leaf primordium with axillar meristematic dome and differentiation of generative elements of flowers in the peak or lateral zone of an apex – mixed buds. The fruit trees of the genus Prunus have purely flower buds and for this purpose the whole apex is taken, between protection – cover leaves, on lateral positions of all collateral buds at shoot nodes. The moment of initiation of determination and the dynamics of differentiation of generative buds are different at different type of shoots on a tree. It is therefore necessary to know the shoots growth cessation time which is in correlation with apex determination. Fruit trees of the genus Prunus are ending the growth of shoots by rejection of shoot peaks, and the cast away time depends on the type, length and the position of shoots.

ГИСТОХИМИЧЕСКОЕ ИЗУЧЕНИЕ КЛЕТОК КСИЛЕМЫ У IRIS SIBIRICA L. В КУЛЬТУРЕ IN VITRO

This paper presents the data content of the lignin from annual plants-regenerants Iris sibirica is comparable to the content of a 6-year-old intact plants. With the aim of identifying conditions of accelerated lignification studied the structure of the shoots of Iris sibirica , grown on artificial nutrient media, using the methods of histochemistry. Peculiarities of the formation of the xylem from Iris sibirica on artificial nutrient media. Very quickly regenerants developed a complex system consisting of conducting bundles containing sieve tubes, vessels and tracheids, and as a network of gidrozit. Hydrocity Iris sibirica in its structure is tracheids with significiance the swelling, but, in contrast to tracheids and vessels of xylem (they are formed on the basis of procube or cambium – lateral special primary or secondary meristem), hydrocity differentiated from the cells of permanent tissues (like phellogen), which probably at the time of differentiation possessed meristematic activity. From Iris sibirica hydrocity thick layer envelops the conductive beam and accompanied him along the escape at a certain height. Due to the formation of the thick fabric of significiance tracheal elements, young regenerants Iris sibirica was high lignin content. The study of the differentiation of xylem elements in the laboratory can serve as a model for our understanding of the processes of formation of wood.

Positive frozen section margins predict local recurrence in R0-resected squamous cell carcinoma of the head and neck

The purpose of this study was to analyse the impact of surgical margins on tumour recurrence and survival of patients with carcinomas of the head and neck. A cohort of 156 patients with primary squamous cell carcinoma of the head and neck treated by local resection with negative margins and neck dissection between 2004 and 2012 was investigated. Margin status in frozen sections and permanent paraffin tissues were analysed and compared to clinical and histopathological parameters as well as to tumour recurrence (local, regional and distant) and disease-specific survival (DSS). Close margins (<5mm) on permanent sections were correlated to high-grade differentiation (p=0.070), lymphangiosis (p=0.009) and positive neck nodes (p=0.025) implicating regional and distant recurrence (p=0.001) as well as unfavorable DSS (p=0.002). Positive margins on initial frozen section analysis revised into negative margins during further surgery were the strongest predictor for local recurrence in uni- and multivariate analysis (p<0.001, hazard ratio 3.34). However, positive frozen section margins were not significantly predictive for DSS (p=0.150). Significant predictors for DSS in univariate analysis were local recurrence (p=0.026), T-stage (p=0.02), N-stage (p<0.001), grading (p=0.02) and lymphangiosis (p=0.001). Multivariate DSS analysis revealed lymph node metastasis (p=0.005) and local recurrence (p=0.017) as significant negative predictors. Close margins on permanent sections are associated with aggressive tumour characteristics, regional and distant metastasis implicating worse DSS. The accuracy of frozen section analysis seems limited as positive frozen section margins revised into negative margins bear a high risk of local recurrence.

Distinctive genetic activity pattern of the human dental pulp between deciduous and permanent teeth.

Human deciduous and permanent teeth exhibit different developmental processes, morphologies, histological characteristics and life cycles. In addition, their pulp tissues react differently to external stimuli, such as the pulp sensitivity test, dental trauma and pulp therapy materials. These suggest differences in gene expression and regulation, and in this study we compared gene-expression profiles of the human dental pulp from deciduous and permanent teeth. Pulp tissues from permanent premolars and deciduous molars aged 11–14 years were extirpated and mRNA was isolated for cDNA microarray analysis, and quantitative real-time PCR (qPCR). Other teeth were used for immunohistochemical analysis (IHC). Microarray analysis identified 263 genes with a twofold or greater difference in expression level between the two types of pulp tissue, 43 and 220 of which were more abundant in deciduous and permanent pulp tissues, respectively. qPCR analysis was conducted for eight randomly selected genes, and the findings were consistent with the cDNA microarray results. IHC confirmed that insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) was broadly expressed in deciduous dental pulp tissue, but minimally expressed in permanent dental pulp tissue. Immunohistochemical analysis showed that calbindin 1 (CALB1), leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), and gamma-aminobutyric acid A receptor beta 1 (GABRB1) were abundantly expressed in permanent predentin/odontoblasts, but only minimally expressed in deciduous dental pulp tissue. These results show that deciduous and permanent pulp tissues have different characteristics and gene expression, suggesting that they may have different functions and responses to therapies focused on pulp or dentin regeneration.

The oncoprotein v-Myb activates transcription of Gremlin 2 during in vitro differentiation of the chicken neural crest to melanoblasts

The neural crest (NC) is a transient dynamic structure of ectodermal origin, found in early vertebrate embryos. The multipotential NC cells migrate along well defined routes, differentiate to various cell types including melanocytes and participate in the formation of various permanent tissues. As there is only limited information about the molecular mechanisms controlling early events in melanocyte specification and development, we exploited the AMV v-Myb transcriptional regulator, which directs differentiation of in vitro chicken NC cells to the melanocyte lineage. This activity is strictly dependent on v-Myb specifically binding to the Myb recognition DNA element (MRE). The two tamoxifen-inducible v-Myb alleles were constructed one which recognizes the MRE and one which does not. These were activated in ex ovo NC cells, and the expression profiles of resulting cells were analyzed using Affymetrix microarrays and RT-PCR. These approaches revealed up-regulation of the BMP antagonist Gremlin 2 mRNA, and down-regulation of mRNAs encoding several epithelial genes including KRT19 as very early events following the activation of melanocyte differentiation by v-Myb. The enforced v-Myb expression in neural tubes of chicken embryos resulted in detectable presence of Gremlin 2 mRNA. However, expression of Gremlin 2 in NC cells did not promote formation of melanocytes suggesting that Gremlin 2 is not the master regulator of melanocytic differentiation.

Levels and distribution of organochlorine pollutants in primary dental tissues and bone of lamb

This study examined the bioconcentration of selected organochlorine pollutants, tetra- and hexa-chlorobiphenyls with planar (PCB-80, PCB-169) and non-planar (PCB-54, PCB-155) structure, and persistent organochlorine pesticides with planar [hexachlorobenzene (HCB)] and non-planar [1,1-bis (4-chlorophenyl)-2,2-dichloroethene (4,4′-DDE)] structure in primary dental tissues (pulp, dentine, and enamel) and mandibular bone of lactationally exposed lambs, and compared it with the organochlorines distribution pattern in permanent dental tissues and bone. Also, the role of pollutants physicochemical properties and tissue specific characteristics in the bioconcentration was assessed. Residual levels of individual pollutants were analyzed by high-resolution gas chromatography with electron-capture detection. Our results showed that transfer of organochlorines to primary hard dental tissues was higher than to permanent hard dental tissues. Metabolically more stable, planar, and toxic organochlorines (e.g. PCB-169 and HCB) predominated in primary hard dental tissues, where they may represent a potential risk for developmental dental defects.

Comparative Gene Expression Analysis of the Human Periodontal Ligament in Deciduous and Permanent Teeth

There are histological and functional differences between human deciduous and permanent periodontal ligament (PDL) tissues. The aim of this study was to determine the differences between these two types of tissue at the molecular level by comparing their gene expression patterns. PDL samples were obtained from permanent premolars (n = 38) and anterior deciduous teeth (n = 31) extracted from 40 healthy persons. Comparative cDNA microarray analysis revealed several differences in gene expression between the deciduous and permanent PDL tissues. These findings were verified by qRT-PCR (quantitative reverse-transcription–polymerase chain reaction) analysis, and the areas where genes are expressed were revealed by immunohistochemical staining. The expressions of 21 genes were up-regulated in deciduous relative to PDL tissues, and those of 30 genes were up-regulated in permanent relative to deciduous PDL tissues. The genes that were up-regulated in deciduous PDL tissues were those involved in the formation of the extracellular matrix (LAMC2, LAMB3, and COMP), tissue development (IGF2BP, MAB21L2, and PAX3), and inflammatory or immune reactions leading to tissue degradation (IL1A, CCL21, and CCL18). The up-regulated genes in permanent PDL tissues were related to tissue degradation (IL6 and ADAMTS18), myocontraction (PDE3B, CASQ2, and MYH10), and neurological responses (FOS, NCAM2, SYT1, SLC22A3, DOCK3, LRRTM1, LRRTM3, PRSS12, and ARPP21). The analysis of differential gene expressions between deciduous and permanent PDL tissues aids our understanding of histological and functional differences between them at the molecular level.

Seasonal Uptake and Partitioning of Macronutrients in Mature ‘Concord’ Grape

Understanding how grape (Vitis L.) vines store nutrients in permanent tissues, how much nutrient vines take up from the soil, and how nutrients are partitioned and redistributed throughout the plant is critical to the development of sound nutrient management practices. This study investigated the seasonal patterns of macronutrient uptake and redistribution in whole ‘Concord’ grape (Vitis labruscana Bailey) vines. The study was conducted in a 42-year-old own-rooted ‘Concord’ vineyard. The site was a furrow-irrigated fine sandy loam. In 2006 and 2007, four vines were excavated at winter pruning, budbreak, three- to four-leaf stage, bloom, veraison, harvest, and postharvest. Each vine was separated into different organs, dried, and weighed to determine biomass, and then ground and analyzed for C, N, P, K, Ca, and Mg. The results showed that the seasonal dynamics of nutrient contents shared a consistent pattern: translocation of nutrients from woody tissues to actively growing organs at the beginning of the season; nutrient uptake from bloom to veraison (P and Mg in 2006), bloom to harvest (N, P, K, and Ca), or veraison to harvest (P and Mg in 2007); and nutrient movement to woody tissues occurring after veraison until leaf fall with no further nutrient uptake. There was a very high accumulation of Ca in permanent structures of the vine, reflecting the high Ca and CaCO3 found in the soils of the region. As a result, the vines had a higher Ca content than all other nutrients throughout the growing season, which is different from findings in other growing areas.

The role of dental pulp cells in resorption of deciduous teeth

To address the question whether dental pulp cells of exfoliating human deciduous teeth have some roles for controlling or regulating the root resorption via secreting key molecules (OPG, RANKL, CSF-1, TGFbeta, MCP-1 and Cbfa-1) in osteoclastogenesis, we used a sensitive reverse transcriptase polymerase chain reaction (RT-PCR) method for detection of mRNA expressions for the cytokines listed. The dental pulps were retrieved from incisor and molar teeth in the late stage of shedding (n = 30) and from sound premolar teeth extracted for orthodontic reasons (control group; n = 30). The RT-PCR assays were used to identify targeted gene expression. Of the cytokines examined, RANKL and CSF-1 expressions showed significantly higher occurrence in deciduous dental pulps than in permanent teeth pulpal tissues (P < .040). The findings may suggest an interactive role for pulp tissue cells in the physiologic root resorption process. The cells of dental pulp may have some cytokine-producing cells which mediate monocyte-macrophage lineage to form osteo/odontoclasts, and the RANKL/RANK system might be involved in human deciduous teeth resorption.

Transcriptional control of chondrocyte fate and differentiation

Chondrogenesis is an essential process in vertebrates. It leads to the formation of cartilage growth plates, which drive body growth and have primary roles in endochondral ossification. It also leads to the formation of permanent cartilaginous tissues that provide major structural support in the articular joints and respiratory and auditory tracts throughout life. Defects in chondrogenesis cause chondrodysostoses and chondrodysplasias. These skeletal malformation diseases account for a significant proportion of birth defects in humans and can dramatically affect a person's expectancy and quality of life. Chondrogenesis occurs when pluripotent mesenchymal cells commit to the chondrocyte lineage, and through a series of differentiation steps build and eventually remodel cartilage. This review summarizes and discusses our current knowledge and lack of knowledge about the chondrocyte differentiation pathway, from mesenchymal cells to growth plate and articular chondrocytes, with a main focus on how it is controlled by tissue patterning and cell differentiation transcription factors, such as, but not limited to, Pax1 and Pax9, Nkx3.1 and Nkx3.2, Sox9, Sox5 and Sox6, Runx2 and Runx3, and c-Maf.

Partitioning and mobilization of starch and N reserves in grapevine (Vitis vinifera L.)

We followed C and N reserves of grapevines grown in trenches under semi-controlled conditions over a 3-year period after planting. Temporal mobilization of stored C and N and subsequent distribution of reserve materials within the vines were described in parallel with 15N uptake, particularly during the third growing season. Storage C in the perennial tissues (roots, trunk, canes) was mainly made of starch, which accumulated in the ray parenchyma of the wood. In the permanent tissues, starch and total nitrogen contents were found to decrease early in the development (bleeding sap, budbreak) whereas, on a concentration basis, they decreased only after stage 7 (first leaf fully expanded). Starch started to accumulate again in the perennial tissues during flowering. The same observation was made with total nitrogen, although N levels were much lower than those of starch. The 15N study showed that N uptake by the roots started at budbreak and increased with vine development, becoming predominant over reserve mobilization only after the onset of flowering. Taken together, these results indicate that the spring growth period can be divided into three main phases: In the first (dormancy to budbreak), significant losses of C and N proceed mainly via root necrosis. In the second period (first leaf to the onset of bloom), a strong mobilization of starch (and, to a lower extent, of N) occurred for supporting vegetative and reproductive growth. At that point, most of the C and N reserves used on the spring flush were those of the roots, rather than those of the old wood (trunk, canes). In the third period (bloom and early berry development), the mobilization process became low and was relieved by N uptake (and CO2 assimilation) supplying nutrients to the sink structures.

Pourquoi les Monocotylédones? Une introduction pour une clé

The Monocots are short of secondary permanent tissues: the loss of cambium makes the ramifications of the vegetative axis mechanically difficult. This loss explains the monocotyledonous charactereristics as the lack of woody structure, the parallel-veined leaves, the replacement of primary root by adventitious roots, the mode of propagation like sympodic types present in perennial bulbs and rhizomes. The presence at the embryo level of only one cotyledon is also the result of the non-branching seedling. The low percentage of epigeal germination is explainable by the fact the seed leaf acquires no chlorophyll and is limited to a sucking function. In another connection, the absence of cork renders the aerial axis frost-tender and confines many taxons to warm areas.