Inhibition of FGF receptor impairs primitive endoderm differentiation in bovine embryos.

The first cellular differentiation event in the pre-implantation embryo results in the trophectoderm (TE) and the inner cell mass (ICM). A second event occurs in the latter, resulting in the epiblast and the primitive endoderm (PE). This second differentiation is still not fully characterized in bovine development, although it is likely to involve FGF signalling. Thus, in this study, we tested the hypothesis that stimulation or inhibition of the FGF pathway during bovine embryo in vitro culture would only interfere with PE differentiation if maintained until later blastocyst stages. At first, we characterized the expression of PE marker SOX17 at different blastocyst stages. Then, we treated in vitro produced embryos during different windows of time: days 5.0-7.0 (D5-D7), D7-D9, and D5-D9 with 1 µg/ml FGF4 and 1 µg/ml heparin or 1 mM FGFR inhibitor, AZD4547. We observed that the SOX17-positive cell number only increases in late-stage blastocysts compared to early stages. Treatment of embryos with FGF4 did not change the number of SOX17-positive cells, while inhibition of FGFR signalling reduced SOX17-positive cells from D5-D7 and completely ablated SOX17 expression when kept until D9. In conclusion, FGFR inhibition repressed PE differentiation in bovine embryos at all time points, although stimulation with FGF4 did not interfere with PE cell numbers.

Effects of fetal bovine serum on trophectoderm and primitive endoderm cell allocation of in vitro-produced bovine embryos.

Supplementing embryonic culture medium with fetal bovine serum (FBS) renders this medium undefined. Glucose and growth factors present in FBS may affect the results of cell differentiation studies. This study tested the hypothesis that FBS supplementation during in vitro culture (IVC) alters cell differentiation in early bovine embryo development. Bovine embryos were produced in vitro and randomly distributed into three experimental groups at 90 h post insemination (90 hpi): the KSOM-FBS group, which consisted of a 5% (v/v) FBS supplementation; the KSOM33 group, with the renewal of 33% of medium volume; and the KSOM-Zero group, without FBS supplementation nor renewal of the culture medium. The results showed that the blastocyst rate (blastocyst/oocytes) at 210 hpi in the KSOM-FBS group was higher than in the KSOM-Zero group but not different from the KSOM33 group. There were no significant changes in metabolism-related aspects, such as fluorescence intensities of CellROX Green and MitoTracker Red or reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD+). Immunofluorescence analysis of CDX2 revealed that the lack of FBS or medium supplementation reduced the number of trophectoderm (TE) cells and total cells. Immunofluorescence analysis revealed a reduction of SOX17-positive cell numbers after FBS supplementation compared with the KSOM33 group. Therefore, we concluded that FBS absence reduced blastocyst rates; however, no reduction occurred when there was a 33% volume renewal of the medium at 90 hpi. We also concluded that FBS supplementation altered TE and primitive endoderm cell allocation during early bovine embryo development.

Nodal and <i>churchill1</i> position the expression of a notch ligand during <i>Xenopus</i> germ layer segregation.

In vertebrates, Nodal signaling plays a major role in endomesoderm induction, but germ layer delimitation is poorly understood. In avian embryos, the neural/mesoderm boundary is controlled by the transcription factor CHURCHILL1, presumably through the repressor ZEB2, but there is scarce knowledge about its role in other vertebrates. During amphibian gastrulation, Delta/Notch signaling refines germ layer boundaries in the marginal zone, but it is unknown the place this pathway occupies in the network comprising Churchill1 and Nodal. Here, we show that <i>Xenopus churchill1</i> is expressed in the presumptive neuroectoderm at mid-blastula transition and during gastrulation, upregulates <i>zeb2</i>, prevents <i>dll1</i> expression in the neuroectoderm, and favors neuroectoderm over endomesoderm development. Nodal signaling prevents <i>dll1</i> expression in the endoderm but induces it in the presumptive mesoderm, from where it activates Notch1 and its target gene <i>hes4</i> in the non-involuting marginal zone. We propose a model where Nodal and Churchill1 position Dll1/Notch1/Hes4 domains in the marginal zone, ensuring the delimitation between mesoderm and neuroectoderm.

Impaired Gene Expression Due to Iodine Excess in the Development and Differentiation of Endoderm and Thyroid Is Associated with Epigenetic Changes.

Background: Thyroid hormone (TH) synthesis is essential for the control of development, growth, and metabolism in vertebrates and depends on a sufficient dietary iodine intake. Importantly, both iodine deficiency and iodine excess (IE) impair TH synthesis, causing serious health problems especially during fetal/neonatal development. While it is known that IE disrupts thyroid function by inhibiting thyroid gene expression, its effects on thyroid development are less clear. Accordingly, this study sought to investigate the effects of IE during the embryonic development/differentiation of endoderm and the thyroid gland. Methods: We used the murine embryonic stem (ES) cell model of in vitro directed differentiation to assess the impact of IE on the generation of endoderm and thyroid cells. Additionally, we subjected endoderm and thyroid explants obtained during early gestation to IE and evaluated gene and protein expression of endodermal markers in both models. Results: ES cells were successfully differentiated into endoderm cells and, subsequently, into thyrocytes expressing the specific thyroid markers Tshr, Slc5a5, Tpo, and Tg. IE exposure decreased the messenger RNA (mRNA) levels of the main endoderm markers Afp, Crcx4, Foxa1, Foxa2, and Sox17 in both ES cell-derived endoderm cells and embryonic explants. Interestingly, IE also decreased the expression of the main thyroid markers in ES cell-derived thyrocytes and thyroid explants. Finally, we demonstrate that DNA methyltransferase expression was increased by exposure to IE, and this was accompanied by hypermethylation and hypoacetylation of histone H3, pointing to an association between the gene repression triggered by IE and the observed epigenetic changes. Conclusions: These data establish that IE treatment is deleterious for embryonic endoderm and thyroid gene expression.

La reactividad constitucional del sujeto: una piedra de rosetta interdisciplinaria / A reatividade constitucional do sujeito. Uma pedra de roseta interdisciplinar / Subject’s constitutional reactivitya: interdisciplinary rosetta stone

Aprender a identificar de manera integral, mixta y dinámica la constitución de un sujeto significa, por un lado, ayudarlo a autoconocerse en su manera de reaccionar (por eso se habla de reactividad constitucional y no más de biotipos o rasgos), de desarrollarse (madurar o destruirse), de relacionarse y aceptar a los demás tal como son; por otro lado, sirve para personalizar diagnóstico, terapia y pronóstico. La historia del constitucionalismo y un esquema sinóptico interdisciplinario (filosofía griega, teología, medicina hipocrática, galénica, homeopática, china, ayurvédica y holística, biología, embriología, bioquímica, fisiopatología, neurología, endocrinología, psicología y espiritualidad) muestra una precisa correspondencia y un denominador común sobre la base de la teoría constitucional embriológica que habla de endoblasto, mesoblasto y ectoblasto. Una coherencia que dura por más de 24 siglos en occidente y pasa también las barreras culturales (oriente y occidente) y paradigmáticas (biomedicina y homeopatía), no puede ser casual.

To learn to identify in an integral, mixed and dynamic way the subject’s constitution means, on one hand, to help him to a self-knowledgement of his reactive way (for this, we speak of constitutional reactivity and no more of biotipe or trait), to develop himself (to mature or to destroy), to join and accept the others like they are; on the other way, it serve to personalize diagnosis, therapy and prognosis. The constitution history and a synoptic interdisciplinary diagram (Greek philosophy, theology, hippocratic, galenic, homeopatic, chinese, ayurvedic and holistic medicines, biology, embriology, biochemistry, physiopathology, neurology, endocrinology, psychology and spirituality) shows a precise link and a common denominator according to an embriologic constitutional theory, that speaks about endoblast, mesoblast and ectoblast. A coherence thas lasts for more than 24 centuries in occident and goes through even the cultural borders (eastern and western world) and paradigmatic logics (biomedicine and homeopaty) cannot be casual.

Aprender a identificar de maneira integral, mista e dinâmica a constituição de um sujeito significa, por um lado, ajudá-lo a se autoconhecer na sua maneira de reagir (por isso se fala de reatividade constitucional e não mais de biotipos ou traços), de desenvolver-se (amadurecer ou destruir-se), de relacionar-se e aceitar os demais taisl como são; por outro lado, serve para personalizar diagnóstico, terapia e prognóstico. A história do constitucionalismo e um esquema sinóptico interdisciplinar (filosofia grega, teologia, medicina hipocrática, galênica, homeopática, chinesa, ayurvédica e holística, biologia, embriologia, bioquímica, fisiopatologia, neurologia, endocrinologia, psicologia e espiritualidade) mostra uma precisa correspondência e um denominador comum sobre a base da teoria constitucional embriológica que fala de endoblasto, mesoblasto e ectoblasto. Uma coerência que dura por mais de 24 séculos no ocidente e ultrapassa também as barreiras culturais (oriente e ocidente) e paradigmáticas (biomedicina e homeopatia), não pode ser casual.

Sipuncula: an emerging model of spiralian development and evolution.

Sipuncula is an ancient clade of unsegmented marine worms that develop through a conserved pattern of unequal quartet spiral cleavage. They exhibit putative character modifications, including conspicuously large first-quartet micromeres and prototroch cells, postoral metatroch with exclusive locomotory function, paired retractor muscles and terminal organ system, and a U-shaped digestive architecture with left-right asymmetric development. Four developmental life history patterns are recognized, and they have evolved a unique metazoan larval type, the pelagosphera. When compared with other quartet spiral-cleaving models, sipunculan development is understudied, challenging and typically absent from evolutionary interpretations of spiralian larval and adult body plan diversity. If spiral cleavage is appropriately viewed as a flexible character complex, then understudied clades and characters should be investigated. We are pursuing sipunculan models for modern molecular, genetic and cellular research on evolution of spiralian development. Protocols for whole mount gene expression studies are established in four species. Molecular labeling and confocal imaging techniques are operative from embryogenesis through larval development. Next-generation sequencing of developmental transcriptomes has been completed for two species with highly contrasting life history patterns, Phascolion cryptum (direct development) and Nephasoma pellucidum (indirect planktotrophy). Looking forward, we will attempt intracellular lineage tracing and fate-mapping studies in a proposed model sipunculan, Themiste lageniformis. Importantly, with the unsegmented Sipuncula now repositioned within the segmented Annelida, sipunculan worms have become timely and appropriate models for investigating the potential for flexibility in spiralian development, including segmentation. We briefly review previous studies, and discuss new observations on the spiralian character complex within Sipuncula.

Dinâmica da inversão do saco vitelino em preás (Galea spixii Wagler, 1831) / Dynamics of yolk sac inversion in galea (Galea spixii Wagler, 1831)

O objetivo deste trabalho foi estudar o período de inversão do saco vitelino bem como a dinâmica resultante deste processo na gestação inicial em preás, utilizando-se microscopia de luz, microscopia eletrônica de varredura e de transmissão. No décimo segundo dia de gestação observou-se o desenvolvimento dos endodermas parietal e visceral delimitando a cavidade do saco vitelino. O endoderma parietal foi evidenciado revestindo a superfície fetal da placenta corioalantoidea bem como contornando o espaço delimitado pela decídua capsular. Estes endodermas apresentaram formato prismático e encontraram-se separados do trofoblasto por uma desenvolvida membrana de Reichert. Já o endoderma visceral continha vasos vitelínicos e possuía vilosidades apenas em determinadas áreas. No décimo quarto dia de gestação verificou-se a inversão do saco vitelino, caracterizada pela degeneração do endoderma parietal e trofoblasto mural, associado ao desaparecimento gradual da membrana de Reichert. Como consequência deste fenômeno, o endoderma visceral passou a constituir uma interface com o epitélio uterino. Após a inversão, o endoderma parietal que permaneceu íntegro foi aquele que se apoiava na superfície da placenta corioalantóidea, apresentando células em formato colunar alto e característica de epitélio pseudoestratificado. O endoderma visceral apresentou numerosas vilosidades apicais principalmente em regiões próximas a placenta corioalantóidea. Com o contínuo desenvolvimento do embrião e placenta corioalantóidea, observou-se o surgimento de importante área de aposição entre os endodermas visceral e parietal. A inversão do saco vitelino representou uma disposição anatômica favorável ao desenvolvimento embrionário, além de ser uma característica evolutiva nesta espécie de roedor.

The aim of this study was to study the time of yolk sac inversion as well as the dynamics resulting from this process in galea throughout pregnancy. For this, conventional histological techniques, scanning electron microscopy and transmission electron microscopy were used. Parietal and visceral endoderm delimiting the yolk sac cavity was observed at 12 days of pregnancy. The parietal endoderm was coating the fetal surface of the chorioallantoic placenta as well as delimiting the decidua capsularis area. This endoderm had prismatic format and were apart from the trophoblast by an enlarged Reichert's membrane. The visceral endoderm had vitelline vessels and there were villi only in certain areas. At 14 days of pregnancy the yolk sac inversion was characterized by the degeneration of parietal endoderm and mural trophoblast, and also the gradual disappearance of the Reichert's membrane. So it made the visceral endoderm establish an interface with the uterine epithelium. After the inversion, the parietal endoderm which remained intact was the one that rested on the chorioallantoic placenta surface. It presented cells with high columnar format and pseudostratified epithelium featured. The visceral endoderm presented many apical villi, especially in areas close to the chorioallantoic placenta. The continued development of the embryo and chorioallantoic placenta evidenced the emergence of an important apposition area between visceral and parietal endoderm. The yolk sac inversion represented an anatomical arrangement in favor of the embryo development as well as an evolutionary trait in this rodent species.

Dinâmica da inversão do saco vitelino em preás (Galea spixii Wagler, 1831) / Dynamics of yolk sac inversion in galea (Galea spixii Wagler, 1831)

O objetivo deste trabalho foi estudar o período de inversão do saco vitelino bem como a dinâmica resultante deste processo na gestação inicial em preás, utilizando-se microscopia de luz, microscopia eletrônica de varredura e de transmissão. No décimo segundo dia de gestação observou-se o desenvolvimento dos endodermas parietal e visceral delimitando a cavidade do saco vitelino. O endoderma parietal foi evidenciado revestindo a superfície fetal da placenta corioalantoidea bem como contornando o espaço delimitado pela decídua capsular. Estes endodermas apresentaram formato prismático e encontraram-se separados do trofoblasto por uma desenvolvida membrana de Reichert. Já o endoderma visceral continha vasos vitelínicos e possuía vilosidades apenas em determinadas áreas. No décimo quarto dia de gestação verificou-se a inversão do saco vitelino, caracterizada pela degeneração do endoderma parietal e trofoblasto mural, associado ao desaparecimento gradual da membrana de Reichert. Como consequência deste fenômeno, o endoderma visceral passou a constituir uma interface com o epitélio uterino. Após a inversão, o endoderma parietal que permaneceu íntegro foi aquele que se apoiava na superfície da placenta corioalantóidea, apresentando células em formato colunar alto e característica de epitélio pseudoestratificado. O endoderma visceral apresentou numerosas vilosidades apicais principalmente em regiões próximas a placenta corioalantóidea. Com o contínuo desenvolvimento do embrião e placenta corioalantóidea, observou-se o surgimento de importante área de aposição entre os endodermas visceral e parietal. A inversão do saco vitelino representou uma disposição anatômica favorável ao desenvolvimento embrionário, além de ser uma característica evolutiva nesta espécie de roedor.(AU)

The aim of this study was to study the time of yolk sac inversion as well as the dynamics resulting from this process in galea throughout pregnancy. For this, conventional histological techniques, scanning electron microscopy and transmission electron microscopy were used. Parietal and visceral endoderm delimiting the yolk sac cavity was observed at 12 days of pregnancy. The parietal endoderm was coating the fetal surface of the chorioallantoic placenta as well as delimiting the decidua capsularis area. This endoderm had prismatic format and were apart from the trophoblast by an enlarged Reichert's membrane. The visceral endoderm had vitelline vessels and there were villi only in certain areas. At 14 days of pregnancy the yolk sac inversion was characterized by the degeneration of parietal endoderm and mural trophoblast, and also the gradual disappearance of the Reichert's membrane. So it made the visceral endoderm establish an interface with the uterine epithelium. After the inversion, the parietal endoderm which remained intact was the one that rested on the chorioallantoic placenta surface. It presented cells with high columnar format and pseudostratified epithelium featured. The visceral endoderm presented many apical villi, especially in areas close to the chorioallantoic placenta. The continued development of the embryo and chorioallantoic placenta evidenced the emergence of an important apposition area between visceral and parietal endoderm. The yolk sac inversion represented an anatomical arrangement in favor of the embryo development as well as an evolutionary trait in this rodent species.(AU)

Embryonic development of endoderm in chicken (Gallus gallus domesticus).

The poultry industry is a sector of agribusiness which represents an important role in the country's agricultural exports. Therefore, the study about embryogenesis of the domestic chicken (Gallus gallus domesticus) has a great economic importance. The aim of this study was to evaluate embryonic development of the endoderm in chicken (Gallus gallus domesticus). Forty fertilized eggs of domestic chickens, starting from the 1st day of gestation and so on until the 19 days of the incubation were collected from the Granja São José (Amparo, SP, Brazil). Embryos and fetus were fixed in 10% formaldehyde solution, identified, weighed, measured, and subjected to light and scanning electron microscopy. The endoderm originates the internal lining epithelium of the digestive, immune, respiratory systems, and the organs can be visualized from the second day (48 h) when the liver is formed. The formation of the digestive system was complete in the 12th day. Respiratory system organs begin at the fourth day as a disorganized tissue and undifferentiated. Their complete differentiation was observed at the 10 days of incubation, however, until the 19 days the syrinx was not observed. The formation of immune system at 10th day was observed with observation of the spleen, thymus, and cloacal bursa. The study of the organogenesis of the chicken based on germ layers is very complex and underexplored, and the study of chicken embryology is very important due the economic importance and growth of the use of this animal model studies such as genetic studies.

Desarrollo del Aparato Digestivo / Digestive System Development

El aparato digestivo deriva del endodermo y el mesodermo, que forman su epitelio y la musculatura lisa respectivamente. Al igual que en el resto de los sistemas, existe un interacción epitelio-mesenquimática mediada por moléculas como Hedgehog, BMP y FoxF1 que determinan el crecimiento intestinal en sus ejes principales. Los genes Hox, junto con el resto de las moléculas, participan en la regionalización del sistema digestivo. En sus inicios lo denominaremos intestino primitivo, formado por un tubo endodérmico que deriva del saco vitelino; dividiéndose en intestino anterior, medio y posterior. En esta revisión veremos cómo estos 3 segmentos darán origen a las diferentes estructuras del sistema digestivo en los vertebrados.

The digestive system is derived from the endoderm and mesoderm, which form its epithelium and smooth muscle, respectively. As in the other systems, there is an epithelial-mesenchymal interactions mediated by molecules such as Hedgehog, BMP and FoxF1, determining intestinal growth in the main axes. The Hox genes, together the rest of the molecules, involved in the regionalization of the digestive system. In the beginning we call it primitive gut, consisting of a tube derived of endodermal yolk sac, divided into foregut, midgut and hindgut. In this review we will see how these 3 segments give rise to different structures of the digestive system in vertebrates.

Molecular analysis of the differentiation potential of murine mesenchymal stem cells from tissues of endodermal or mesodermal origin.

Mesenchymal stem cells (MSCs) have received great attention due to their remarkable regenerative, angiogenic, antiapoptotic, and immunosuppressive properties. Although conventionally isolated from the bone marrow, they are known to exist in all tissues and organs, raising the question on whether they are identical cell populations or have important differences at the molecular level. To better understand the relationship between MSCs residing in different tissues, we analyzed the expression of genes related to pluripotency (SOX2 and OCT-4) and to adipogenic (C/EBP and ADIPOR1), osteogenic (OMD and ALP), and chondrogenic (COL10A1 and TRPV4) differentiation in cultures derived from murine endodermal (lung) and mesodermal (adipose) tissue maintained in different conditions. MSCs were isolated from lungs (L-MSCs) and inguinal adipose tissue (A-MSCs) and cultured in normal conditions, in overconfluence or in inductive medium for osteogenic, adipogenic, or chondrogenic differentiation. Cultures were characterized for morphology, immunophenotype, and by quantitative real-time reverse transcription-polymerase chain reaction for expression of pluripotency genes or markers of differentiation. Bone marrow-derived MSCs were also analyzed for comparison of these parameters. L-MSCs and A-MSCs exhibited the typical morphology, immunophenotype, and proliferation and differentiation pattern of MSCs. The analysis of gene expression showed a higher potential of adipose tissue-derived MSCs toward the osteogenic pathway and of lung-derived MSCs to chondrogenic differentiation, representing an important contribution for the definition of the type of cell to be used in clinical trials of cell therapy and tissue engineering.

Genetic diversity of root anatomy in wild and cultivated Manihot species.

An anatomical study of roots was conducted on two wild Manihot species, namely M. glaziovii and M. fortalezensis, and two cassava varieties, M. esculenta Crantz variety UnB 201 and M. esculenta variety UnB 122, to identify taxonomic differences in primary growth. Anatomical characters of cassava roots have been rarely investigated. Their study may help cassava breeders to identify varieties with economically important characters, such as tolerance to drought. We investigated tap and lateral adventitious roots of two specimens of each clone or species. Free-hand cross-sections of roots were drawn; these had been clarified with 20% sodium hypochlorite solution, stained with 1% safranin-alcian blue ethanolic solution, dehydrated in ethanol series and butyl acetate and mounted in synthetic resin. Anatomical differences among Manihot species and varieties were found in the epidermal and exodermal cell shape and wall thickness, content of cortical parenchyma, and number of xylem poles. Wall thickness of the epidermis and exodermis of tap root were similar in all species, while in the lateral root there were differences in cell shape and wall thickness. Epidermal cells with thick walls were found in the tap root of all species and in lateral roots of cassava varieties. This character is apparently associated with tolerance to drought and disease. The variation in the number of xylem poles of cassava varieties was larger (4-8) than in wild species (4-6), and appears to support the hybrid origin of cassava.

Delta-Notch signaling is involved in the segregation of the three germ layers in Xenopus laevis.

In vertebrates, the induction of the three germ layers (ectoderm, mesoderm and endoderm) has been extensively studied, but less is known about how they segregate. Here, we investigated whether Delta-Notch signaling is involved in this process. Activating the pathway in the marginal zone with Notch(ICD) resulted in an expansion of endodermal and neural ectoderm precursors, leaving a thinner mesodermal ring around the blastopore at gastrula stage, when germ layers are segregated. On the other hand, when the pathway was blocked with Delta-1(STU) or with an antisense morpholino oligonucleotide against Notch, the pan-mesodermal brachyury (bra) domain was expanded and the neural border was moved animalwards. Strikingly, the suprablastoporal endoderm was either expanded when Delta-1 signaling was blocked, or reduced after the general knock-down of Notch. In addition, either activating or blocking the pathway delays the blastopore closure. We conclude that the process of delimiting the three germ layers requires Notch signaling, which may be finely regulated by ligands and/or involve non-canonical components of the pathway. Moreover, Notch activity must be modulated at appropriate levels during this process in order to keep normal morphogenetic movements during gastrulation.

Differential Shh, Bmp and Wnt gene expressions during craniofacial development in mice.

In this study, Bmp-4, Wnt-5a and Shh gene expressions were compared during early craniofacial development in mice by comparative non-isotopic in situ hybridization. Wild-type C57BL/6J mice were studied at various stages of embryonic development (from 8.5- to 13.5-day-old embryos--E8.5-13.5). During early odontogenesis, transcripts for Bmp-4, Shh and Wnt-5a were co-localised at the tooth initiation stage. At E8.5, Shh mRNA expression was restricted to diencephalon and pharyngeal endoderm. Before maxillae and mandible ossification, Bmp-4 and Wnt-5a signals were detected in the mesenchymal cells and around Meckel's cartilage. During palatogenesis, Shh was expressed only in the epithelium and Wnt-5a only in the mesenchyme of the elevating palatal shelves. During tongue development, Shh expression was found in mesenchyme, probably contributing to tongue miogenesis, while Wnt-5a signal was in the epithelium, possibly during placode development and papillae formation. Taken together, these findings suggest that Bmp-4, Shh and Wnt-5a gene expressions may act together on the epithelial-mesenchymal interactions occurring in several aspects of the early mouse craniofacial development, such as odontogenesis, neuronal development, maxillae and mandible ossification, palatogenesis and tongue formation.

Comparative analysis of Xenopus VegT, the meso-endodermal determinant, identifies an unusual conserved sequence.

The transcription factor, VegT, is the meso-endodermal determinant in Xenopus laevis. We examined VegT orthologs from several anuran amphibians and the urodele amphibian, the Mexican axolotl. In addition to the conserved T-box, the DNA-binding domain, the orthologs share a conserved 57 amino acid domain at the C-terminal. Most striking is a 17-nucleotide (nt) sequence near the 3' end of the open reading frame. The 17 nts are absolutely conserved among the anurans, whose last common ancestor lived 200 million years ago. As an initial test of the function of the 17 nts, 27 or 49 amino acids, which include the six amino acids coded by the 17 (+1) nts, were deleted from the C-terminal of VegT. These truncated VegT's retained some transcriptional activity, indicating that the 17 nts are not absolutely required for this function. The function of the highly conserved 17 nts is unknown. Two possibilities are that the conserved 17 nts interact with the cytoskeleton or that they are a target for regulation by a microRNA.

The pulvinus endodermal cells and their relation to leaf movement in legumes of the Brazilian cerrado.

Legume pulvini have a clearly delimited endodermis, whose variable content has been associated with the velocity and type of leaf movement: pulvini in leaves with fast nastic movement contain starch grains; pulvini in leaves with slow nastic movements have calcium oxalate crystals as well as starch grains in the endodermis. However, the studies carried out to date have involved few legume species. This study therefore purported to examine the consistency of this hypothesis in other legumes. Thus, the structure and content of the pulvinus endodermal cells of nine legumes of the Brazilian cerrado, with different types and velocities of leaf movement, were investigated: slow nyctinastic and heliotropic movements ( BAUHINIA RUFA, COPAIFERA LANGSDORFFII, SENNA RUGOSA - Caesalpinioideae; ANDIRA HUMILIS and DALBERGIA MISCOLOBIUM - Faboideae; STRYPHNODENDRON POLYPHYLLUM - Mimosoideae), slow heliotropic movement ( ZORNIA DIPHYLLA - Faboideae), and fast seismonastic and slow nyctinastic and heliotropic movements ( MIMOSA RIXOSA and MIMOSA FLEXUOSA - Mimosoideae). Samples were prepared following standard plant anatomy and ultrastructure techniques. The endodermis of all the species contains starch grains. In the species displaying only slow movements, calcium oxalate prismatic crystals were observed in addition to starch grains, except in ZORNIA DIPHYLLA. In conclusion, oxalate crystals occur only in endodermal cells of pulvini that display slow movements, while starch grains are always present in pulvinus endodermal cells of plants with any kind of movement.

Meristematic activity of the Endodermis and the Pericycle in the primary thickening in monocotyledons: considerations on the "PTM"

A proposta deste trabalho é mostrar uma nova interpretação do meristema de espessamento primário em monocotiledôneas. Anatomia dos órgãos vegetativos das seguintes espécies foi examinada: Cephalostemon riedelianus (Rapataceae), Cyperus papyrus (Cyperaceae), Lagenocarpus rigidus, L. Junciformis (Cyperaceae), Echinodorus paniculatus (Alismataceae) and Zingiberofficinale (Zingiberaceae). A atividade meristemática da endoderme foi observada nas raizes de todas as espécies, no caule de Cyperus, Cephalostemum e Lagenocarpus rigidus, e no traço foliar de Cyperus e folha de Echinodorus. Considerando a continuidade dos tecidos através da raiz, caule e folha, as autoras concluem que no caule o periciclo permanece ativo durante a vida da planta, como um gerador de tecidos vasculares. O "Meristema de Espessamento Primário" é o periciclo em fase meristemática, juntamente com a endoderme e suas derivadas (ou apenas o periciclo). Próximo ao ápice caulinar, esses tecidos se assemelham a um único meristema, dando origem ao córtex interno e aos tecidos vasculares.

Meristematic activity of the Endodermis and the Pericycle in the primary thickening in monocotyledons: considerations on the "PTM".

This paper proposes a new interpretation for primary thickening in monocotyledons. The anatomy of the vegetative organs of the following species was examined: Cephalostemon riedelianus (Rapataceae), Cyperus papyrus (Cyperaceae), Lagenocarpus rigidus, L. junciformis (Cyperaceae), Echinodorus paniculatus (Alismataceae) and Zingiber officinale (Zingiberaceae). The endodermis with meristematic activity was observed in the root of all the species, in the stem of Cyperus, Cephalostemum and Lagenocarpus rigidus, and in the leaf trace of Cyperus and leaf of Echinodorus. Considering the continuity of tissues through the root, stem and leaf, the authors conclude that in the stem the pericycle remains active throughout the life of the plant as the generator of the vascular tissue. The "Primary Thickening Meristem" is in fact the pericycle plus the endodermis and its derivatives (or only the pericycle). Close to the stem apex, the assemblage of seems to be a unique meristem, giving rise to the inner cortex and vascular tissues.

Morphogenesis of extraembryonic membranes and placentation in Mabuya mabouya (Squamata, Scincidae).

Topological and histological analyses of Mabuya mabouya embryos at different developmental stages showed an extraembryonic membrane sequence as follows: a bilaminar omphalopleure and progressive mesodermal expansion around the whole yolk sac at gastrula stages; mesodermal split and formation of an exocoelom in the entire embryonic chamber at neurula stages; beginning of the expansion of the allantois into the exocoelom to form a chorioallantoic membrane at pharyngula stages; complete extension of the allantois into the exocoelom between limb-bud to preparturition stages. Thus, a placental sequence could be enumerated: bilaminar yolk sac placenta; chorioplacenta; allantoplacenta. All placentas are highly specialized for nutrient absorption from early developmental stages. The bistratified extraembryonic ectoderm possesses an external layer with cuboidal cells and a microvillar surface around the whole yolk sac, which absorbs uterine secretions during development of the bilaminar yolk sac placenta and chorioplacenta. During gastrulation, with mesodermal expansion a dorsal absorptive plaque forms above the embryo and several smaller absorptive plaques develop antimesometrially. Both structures are similar histologically and are active in histotrophic transfer from gastrula stages until the end of development. The dorsal absorptive plaque will constitute the placentome and paraplacentome during allantoplacental development. At late gastrula-early neurula stages some absorptive plaques form chorionic concavities or chorionic bags that are penetrated by a long uterine fold and seem to have a specialized histotrophic and/or metabolic role. The extraembryonic mesoderm does not ingress into the yolk sac and neither an isolated yolk mass nor a yolk cleft are formed. This derived pattern of development may be related to the drastic reduction of the egg size and obligatory placentotrophy from early developmental stages. Our results show new specialized placentotrophic structures and a novel arrangement of extraembryonic membrane morphogenesis for Squamata.