Differential effects of thyroid hormone manipulation and ß adrenoceptor agonist administration on uncoupling protein mRNA abundance in adipose tissue and thermoregulation in neonatal pigs

We have shown that there is significant disparity in the expression of uncoupling proteins (UCP) 2 and 3 between modern-commercial and ancient-Meishan porcine genotypes, commercial pigs also have higher plasma triiodothyronine (T(3)) in on the first day of life. T(3) and the sympathetic nervous system are both known to regulate UCPs in rodents and humans; their role in regulating these proteins in the pig is unknown. This study examined whether thyroid hormone manipulation or administration of a selective beta3 adrenoceptor agonist (ZD) influenced plasma hormones, colonic temperature and UCP expression in adipose tissue of two breeds of pig. To mimic the differences observed in thyroid hormone status, piglets from Meishan and commercial litters were randomly assigned to control (1 ml/kg water), T(3) (10 mg/kg) (Meishan only), methimazole (a commonly used antithyroid drug) (50 mg/kg) (commercial only) or ZD (10 mg/kg) oral administration for the first 4 days of postnatal life. Adipose tissue UCP2/3 mRNA abundance was measured on day 4 using PCR. T(3) administration raised plasma T(3) concentrations and increased colonic temperature on day 4. UCP3 mRNA abundance was higher in Meishan, than commercial piglets (p = 0.042) and was downregulated following T(3) administration (p = 0.014). Irrespective of genotype, ZD increased UCP2 mRNA abundance (Meishan p = 0.05, commercial p = 0.03). Expression of neither UCP2 nor 3 was related to colonic temperature, regardless of treatment. In conclusion, we have demonstrated a dissociation between thyroid hormones and the sympathetic nervous system in the regulation of UCPs in porcine adipose tissue. We have also suggested that expression of adipose tissue UCP2 and 3 are not related to body temperature in piglets.

Comparative genomics suggests that an ancestral polyploidy event leads to enhanced root nodule symbiosis in the Papilionoideae

Root nodule symbiosis (RNS) is one of the most efficient biological systems for nitrogen fixation and it occurs in 90% of genera in the Papilionoideae, the largest subfamily of legumes. Most papilionoid species show evidence of a polyploidy event occurred approximately 58 million years ago. Although polyploidy is considered to be an important evolutionary force in plants, the role of this papilionoid polyploidy event, especially its association with RNS, is not understood. In this study, we explored this role using an integrated comparative genomic approach and conducted gene expression comparisons and gene ontology enrichment analyses. The results show the following: (1) approximately a quarter of the papilionoid-polyploidy-derived duplicate genes are retained; (2) there is a striking divergence in the level of expression of gene duplicate pairs derived from the polyploidy event; and (3) the retained duplicates are frequently involved in the processes crucial for RNS establishment, such as symbiotic signalling, nodule organogenesis, rhizobial infection and nutrient exchange and transport. Thus, we conclude that the papilionoid polyploidy event might have further refined RNS and induced a more robust and enhanced symbiotic system. This conclusion partly explains the widespread occurrence of the Papilionoideae.

Ethylene and polyamine interactions in morphogenesis of Passiflora cincinnata: effects of ethylene biosynthesis and action modulators, as well as ethylene scavengers

Ethylene is a plant hormone that is of fundamental importance to in vitro morphogenesis, but in many species, it has not been thoroughly studied. Its relationship with polyamines has been studied mainly because the two classes of hormones share a common biosynthetic precursor, S-adenosylmethionine (SAM). In order to clarify whether competition between polyamines and ethylene influences in vitro morphogenetic responses of Passiflora cincinnata Mast., a climacteric species, different compounds were used that act on ethylene biosynthesis and action, or as ethylene scavengers. Treatment with the ethylene inhibitor, aminoethoxyvinylglycine (AVG) caused a greater regeneration frequency in P. cincinnata, whereas treatment with the ethylene precursor, 1-aminocyclopropane-1-carboxylic-acid (ACC) lessened regeneration frequencies. The data suggested that levels of polyamines and ethylene are not correlated with morphogenic responses in P. cincinnata. It was ascertained that neither the absolute ethylene and polyamine levels, nor competition between the compounds, correlated to the obtained morphogenic responses. However, sensitivity to, and signaling by, ethylene appears to play an important role in differentiation. This study reinforces previous reports regarding the requirement of critical concentrations and temporal regulation of ethylene levels for morphogenic responses. Temporal regulation also appeared to be a key factor in competition between the two biosynthetic pathways, without having any effects on morphogenesis. Further studies investigating the silencing or overexpression of genes related to ethylene perception, under the influence of polyamines in cell differentiation are extremely important for the complete understanding of this process.

A novel regeneration system for a wild passion fruit species (Passiflora cincinnata Mast.) based on somatic embryogenesis from mature zygotic embryos

The objective of the present work was to induce somatic embryogenesis from zygotic embryos of Passiflora cincinnata Masters. Zygotic embryos formed calli on media with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4.5 mu M benzyladenine (BA) after 30 days of in vitro culture. A concentration of 18.1 mu M 2,4-D resulted in the largest number of somatic embryos. Embryogenic calli were yellowish and friable, forming whitish proembryogenic masses. Morphologically, embryogenic cells were small and had large nuclei and dense cytoplasm, whereas non-embryogenic cells were elongated, with small nuclei and less dense cytoplasm. Calli cultured under white light on basal Murashige and Skoog`s medium with activated charcoal produced embryos in all developmental stages. There were differences among the treatments, with some leading to the production of calli with embryos and some only to callus formation. Some abnormalities were associated with somatic embryos, including fused axes, fused cotyledons and polycotyledonary embryos. Production of secondary somatic embryos occurred in the first cycle of primary embryo development. Secondary embryos differentiated from the surface of the protodermal layer of primary embryos with intense cell proliferation, successive mitotic divisions in the initial phase of embryoid development, and a vascular system formed with no connection to the parental tissue. This secondary embryogenic system of P. cincinnata is characterized by intense proliferation and maintenance of embryogenic competence after successive subcultures. This reproducible protocol opens new prospects for massive propagation and is an alternative to the current organogenesis-based transformation protocol.

Distribution of small Rho GTPases in the developing rat submandibular gland

During the rat submandibular gland (SMG) development, organogenesis and cytodifferentiation depend on the actin cytoskeleton, which is regulated by small Rho GTPases. These proteins link cell surface receptors to pathways that regulate cell motility, polarity, gene expression, vesicular trafficking, proliferation and apoptosis. The aim of this study was to evaluate, by immunohistochemistry, the distribution pattern of RhoA, RhoB, RhoC, Rac1 and Cdc42 during cytodifferentiation of the rat SMG and in male adults. All GTPases were found in epithelial and mesenchymal tissues throughout gland development. Rac1 appeared to be important for parenchyma expansion at the beginning of cytodifferentiation, while RhoC, Cdc42 and the inactive phosphorylated form of Rac1 seemed associated with lumen formation and cell polarization in terminal tubules. RhoA and RhoB labeling was evident throughout development. All GTPases were differentially expressed in the adult gland, suggesting that they play specific roles during differentiation and function of the rat SMG.

Developmental changes in the expression of creatine synthesizing enzymes and creatine transporter in a precocial rodent, the spiny mouse

Background : Creatine synthesis takes place predominately in the kidney and liver via a two-step process involving AGAT (L-arginine:glycine amidinotransferase) and GAMT (guanidinoacetate methyltransferase). Creatine is taken into cells via the creatine transporter (CrT), where it plays an essential role in energy homeostasis, particularly for tissues with high and fluctuating energy demands. Very little is known of the fetal requirement for creatine and how this may change with advancing pregnancy and into the early neonatal period. Using the spiny mouse as a model of human perinatal development, the purpose of the present study was to comprehensively examine the development of the creatine synthesis and transport systems.

Results : The estimated amount of total creatine in the placenta and brain significantly increased in the second half of pregnancy, coinciding with a significant increase in expression of CrT mRNA. In the fetal brain, mRNA expression of AGAT increased steadily across the second half of pregnancy, although GAMT mRNA expression was relatively low until 34 days gestation (term is 38–39 days). In the fetal kidney and liver, AGAT and GAMT mRNA and protein expression were also relatively low until 34–37 days gestation. Between mid-gestation and term, neither AGAT or GAMT mRNA or protein could be detected in the placenta.

Conclusion : Our results suggest that in the spiny mouse, a species where, like the human, considerable organogenesis occurs before birth, there appears to be a limited capacity for endogenous creatine synthesis until approximately 0.9 of pregnancy. This implies that a maternal source of creatine, transferred across the placenta, may be essential until the creatine synthesis and transport system matures in preparation for birth. If these results also apply to the human, premature birth may increase the risk of creatine deficiency.

ZebRA: an overview of retinoic acid signaling during zebrafish development

Retinoic acid (RA), the main active vitamin A derivative, is crucial for embryo development, regulating cellular processes, embryo patterning and organogenesis. Many studies performed in mammalian or avian models have successfully undertaken the investigation of the role played by RA during embryogenesis. Since the early 1980s, the zebrafish (Danio rerio) has emerged as a powerful developmental model to study the in vivo role of RA during embryogenesis. Unlike mammalian models, zebrafish embryogenesis is external, not only allowing the observation of the translucent embryo from the earliest steps but also providing an easily accessible system for pharmacological treatment or genetic approaches. Therefore, zebrafish research largely participates in deciphering the role of RA during development. This review aims at illustrating different concepts of RA signaling based on the research performed on zebrafish. Indeed, RA action relies on a multitude of cross-talk with other signaling pathways and requires a coordinated, dynamic and fine-regulation of its level and activity in both temporal and spatial dimensions. This review also highlights major advances that have been discovered using zebrafish such as the observation of the RA gradient in vivo for the first time, the effects of RA signaling in brain patterning, its role in establishing left-right asymmetry and its effects on the development of a variety of organs and tissues including the heart, blood, bone and fat. This review demonstrates that the zebrafish is a convenient and powerful model to study retinoic acid signaling during vertebrate embryogenesis. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

Urea-based osmoregulation in the developing embryo of oviparous cartilaginous fish (Callorhinchus milii) : contribution of the extraembryonic yolk sac during the early developmental period

Marine cartilaginous fish retain a high concentration of urea to maintain the plasma slightly hyperosmotic to the surrounding seawater. In adult fish, urea is produced by hepatic and extrahepatic ornithine urea cycles (OUCs). However, little is known about the urea retention mechanism in developing cartilaginous fish embryos. In order to address the question as to the mechanism of urea-based osmoregulation in developing embryos, the present study examined the gene expression profiles of OUC enzymes in oviparous holocephalan elephant fish (Callorhinchus milii) embryos. We found that the yolk sac membrane (YSM) makes an important contribution to the ureosmotic strategy of the early embryonic period. The expression of OUC enzyme genes was detectable in the embryonic body from at least stage 28, and increased markedly during development to hatching, which is most probably due to growth of the liver. During the early developmental period, however, the expression of OUC enzyme genes was not prominent in the embryonic body. Meanwhile, we found that the mRNA expression of OUC enzymes was detected in the extra-embryonic YSM; the mRNA expression of cmcpsIII in the YSM was much higher than that in the embryonic body during stages 28-31. Significant levels of enzyme activity and the existence of mitochondrial-type cmgs1 transcripts in the YSM supported the mRNA findings. We also found that the cmcpsIII transcript is localized in the vascularized inner layer of the YSM. Taken together, our findings demonstrate for the first time that the YSM is involved in urea-based osmoregulation during the early to mid phase of development in oviparous cartilaginous fish.

Placas maxilo-dentárias em Rincossauros Hyperodapedon Huxley, 1859. Histologia e morfogênese maxilo-dental: nova abordagem.

O estudo das estruturas da placas maxilo-dentárias dos rincossauros Hyperodapedon Huxley, 1859, do Triássico da Formação Santa Maria, em nova abordagem histológica e ontogênica resultou na identificação da natureza do esmalte aprismático verdadeiro, de variados elementos histológicos dentinários e osteológicos, e de um centro de ossificação periosteal primário. Também foram encontradas evidências histológicas dos mecanismos de fusionamento maxilo-dentinário e amelo-maxilar. Com estes elementos, inferimos os modelos de organogênese dental, da ontogênese maxilar e dos mecanismos de fusionamento maxilodental. Encontrou-se uma singular e raríssima coroa dental, imatura e ainda não erupcionada, na região posterior da placa dental e assim evidenciou-se a correta posição da margem odontogenicamente ativa. Adicionalmente inferiu-se a localização da posição da lâmina dentária embrionária. Constatou-se a não formação de alvéolos dentários, de cemento radicular e do espaço necessário à formação do ligamento periodontal e, assim, se deduziu a não formação do folículo dental embriônico. As presenças de especiais elementos anatômicos e histológicos nos tecidos ósseos periapicais evidenciam o crescimento radicular contínuo, enquanto a forma e o fusionamento radicular imediato depõe a favor de uma função dentária fisiológica diferenciada para as baterias dentárias maxilares dos Rincossauros do gênero Hyperodapedon. Os mecanismos que possibilitaram o controle embriônico para a deposição das lamelas de tecido ósseo coronal e seu preciso fusionamento sobre o esmalte dentário, declinam por modificações nas funções tardias do órgão reduzido do esmalte e pela presença de uma membrana oral com funções osteogênicas e também protetivas, situada nas porções posteriores da placa maxilo-dentária em desenvolvimento. Mudanças heterocrônicas no tempo de diferenciação das células da crista neural embriônica e em seus derivados, como a lâmina dentária e órgãos dentários embrionários ou correlacionadas com a organogênese das placas maxilo-dentárias e seus anexos periodontais, todos como condições plesiomórficas para Diápsidas Triássicos, poderiam ser as causas responsáveis pela origem e evolução deste estranho aparelho estomatognático nos clados de Hyperodapedon sp..

Crescimento e estruturas do sistema digestório de larvas de pacu alimentadas com dieta microencapsulada produzida experimentalmente

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Brycon gouldingi (Teleostei, Characidae): aspects of the embryonic development in a new fish species with aquaculture potential

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Meios de cultura no desenvolvimento de ápices caulinares de mamoneira (Ricinus communis L.) in vitro

A pesquisa da composição do meio de cultura mais adequado à espécie vegetal e ao tipo de explante empregado é o fator de maior relevância da cultura de tecidos. O cultivo de ápice caulinar com recuperação da planta matriz é uma técnica de grande impacto para a propagação de plantas in vitro, regeneração de plantas livres de vírus, conservação de germoplasma e modificação genética. Objetivou-se, neste trabalho, avaliar composições do meio de cultivo para organogênese direta in vitro a partir de ápices caulinares pertencentes à população FCA-UNESP-PB de mamoneira (Ricinus communis L.), com vistas à propagação clonal de genótipos elite. Foram testadas quatro formulações: MS básico (T1), MS modificado 1 (T2), MS modificado 2 (T3) e WPM (T4), em delineamento experimental inteiramente casualizado, com 20 repetições em cada tratamento, sendo a repetição 1 ápice caulinar/frasco. O T3 apresentou-se superior e diferiu significativamente dos outros tratamentos apresentando 35% dos ápices caulinares diferenciados e desenvolvidos; seguiu-se o T2 com 10% e os tratamentos T1 e T4 não apresentaram diferenciação de tecidos. Os resultados permitiram concluir que os balanceamentos de sais minerais nos meios de cultura avaliados, especialmente a relação NO3 / NH4 e ausência de FeSO4.7H2O, indicaram grande influência no desenvolvimento de ápices caulinares de mamoneira.

Cultura de embrião e indução de brotos in vitro para micropropagação do pinhão-manso

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeitos dos esteroides anabólicos androgênicos sobre o útero e parâmetros reprodutivos de ratas adultas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural analysis of the Pimelodus maculatus (Lacépède, 1803) embryogenesis (Siluriformes: Pimelodidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)