Axl -Gas6 signaling counteracts adenovirus type 5 E1A-mediated cell growth suppression and proapoptotic activity

The adenovirus type 5 E1A (abbreviated E1A) has previously been known as an immortalization oncogene because E1A is required for transforming oncogenes, such as ras and E1B, to transform cells in primary cultures. However, E1A has also been shown to downregulate the overexpression of the Her-2/neu oncogene, resulting in suppression of transformation and tumorigenesis induced by that oncogene. In addition, E1A is able to promote apoptosis induced by anticancer drugs, irradiation, and serum deprivation. Many tyrosine kinases, such as the EGF receptor, Her-2/Neu, Src, and Axl are known to play a role in oncogenic signals in transformed cells. To study the mechanism underlying the E1A-mediated tumor-suppressing function, we exploited a modified tyrosine kinase profile assay (Proc. Natl. Acad. Sci, 93, 5958–5962, 1996) to identify potential tyrosine kinases regulated by E1A. RT-PCR products were synthesized with two degenerate primers derived from the conserved motifs of various tyrosine kinases. A tyrosine kinase downregulated by E1A was identified as Axl by analyzing the Alu I-digested RT-PCR products. We isolated the DNA fragment of interest, and found that E1A negatively regulated the expression of the transforming receptor tyrosine kinase Axl at the transcriptional level. To study whether downregulation of the Axl receptor is involved in E1A-mediated growth suppression, we transfected axl cDNA into E1A-expressing cells (ip1-E1A) to establish cells that overexpressed Axl (ip1-E1A-Axl). The Axl ligand Gas6 triggered a greater mitogenic effect in these ip1-E1A-Axl cells than in the control cells ip1-E1A and protected the Axl-expressing cells from serum deprivation-induced apoptosis. Further study showed that Akt is required for Axl-Gas6 signaling to prevent ip1-E1A-Axl cells from serum deprivation-induced apoptosis. These results indicate that downregulation of the Axl receptor by E1A is involved in E1A-mediated growth suppression and E1A-induced apoptosis, and thereby contributes to E1A's anti-tumor activities. ^

Age, annual coral growth rates and stable isotopes of coral sample Ningaloo

116-year record of coral skeletal delta18O is presented from a colony of Porites lutea from Ningaloo Reef, western Australia. Interannual variability of sea-surface temperatures (SST) inferred from skeletal delta18O is dominated by a 9.5-year period, and may constitute a characteristic signal of the Leeuwin Current. On long-terms coral skeletal delta18O indicates a near-continuous increase of SST at Ningaloo Reef over one century. The skeletal delta18O time series was checked for the presence of seasonal cooling events resulting from major volcanic eruptions. An ~1 °C cooling is evident following the eruption of Pinatubo in 1991, which reproduces the results of previous investigations. However, only weak or no signals can be related to the eruptions of Krakatau (1883) and Agung (1963).

Seawater carbonate chemistry and early development of the sea urchin Lytechinus variegatus in a laboratory experiment using artificial seawater

Land-based aquaculture facilities often utilize additional bicarbonate sources such as commercial sea salts that are designed to boost alkalinity in order to buffer seawater against reductions in pH. Despite these preventative measures, many facilities are likely to face occasional reductions in pH and corresponding reductions in carbonate saturation states due to the accumulation of metabolic waste products. We investigated the impact of reduced carbonate saturation states (Omega Ca, Omega Ar) on embryonic developmental rates, larval developmental rates, and echinoplutei skeletal morphometrics in the common edible sea urchin Lytechinus variegatus under high alkalinity conditions. Commercial artificial seawater was bubbled with a mixture of air and CO2 gas to reduce the carbonate saturation state. Rates of embryonic and larval development were significantly delayed in both the low and extreme low carbonate saturation state groups relative to the control at a given time. Although symmetry of overall skeletal body lengths was not affected, allometric relationships were significantly different between treatment groups. Larvae reared under ambient conditions had significantly greater postoral arm and overall body lengths relative to body lengths than larvae grown under extreme low carbonate saturation state conditions, indicating that extreme changes in the carbonate system affected not only developmental rates but also larval skeletal shape. Reduced rates of embryonic development and delayed and altered larval skeletal growth are likely to negatively impact larval culturing of L. variegatus in land-based, intensive culture situations where calcite and aragonite saturation states are lowered by the accumulation of metabolic waste products.

Seawater carbonate chemistry and larval development and settlement of the sea urchin Arbacia lixula in a laboratory experiment

We studied the effects of temperature and pH on larval development, settlement and juvenile survival of a Mediterranean population of the sea urchin Arbacia lixula. Three temperatures (16, 17.5 and 19 °C) were tested at present pH conditions (pHT 8.1). At 19 °C, two pH levels were compared to reflect present average (pHT 8.1) and near-future average conditions (pHT 7.7, expected by 2100). Larvae were reared for 52-days to achieve the full larval development and complete the metamorphosis to the settler stage. We analyzed larval survival, growth, morphology and settlement success. We also tested the carry-over effect of acidification on juvenile survival after 3 days. Our results showed that larval survival and size significantly increased with temperature. Acidification resulted in higher survival rates and developmental delay. Larval morphology was significantly altered by low temperatures, which led to narrower larvae with relatively shorter skeletal rods, but larval morphology was only marginally affected by acidification. No carry-over effects between larvae and juveniles were detected in early settler survival, though settlers from larvae reared at pH 7.7 were significantly smaller than their counterparts developed at pH 8.1. These results suggest an overall positive effect of environmental parameters related to global change on the reproduction of A. lixula, and reinforce the concerns about the increasing negative impact on shallow Mediterranean ecosystems of this post-glacial colonizer.

Mixed effects of elevated pCO2 on fertilisation, larval and juvenile development and adult responses in the mobile subtidal scallop Mimachlamys asperrima (Lamarck, 1819)

Ocean acidification is predicted to have severe consequences for calcifying marine organisms especially molluscs. Recent studies, however, have found that molluscs in marine environments with naturally elevated or fluctuating CO2 or with an active, high metabolic rate lifestyle may have a capacity to acclimate and be resilient to exposures of elevated environmental pCO2. The aim of this study was to determine the effects of near future concentrations of elevated pCO2 on the larval and adult stages of the mobile doughboy scallop, Mimachlamys asperrima from a subtidal and stable physio-chemical environment. It was found that fertilisation and the shell length of early larval stages of M. asperrima decreased as pCO2 increased, however, there were less pronounced effects of elevated pCO2 on the shell length of later larval stages, with high pCO2 enhancing growth in some instances. Byssal attachment and condition index of adult M. asperrima decreased with elevated pCO2, while in contrast there was no effect on standard metabolic rate or pHe. The responses of larval and adult M. asperrima to elevated pCO2 measured in this study were more moderate than responses previously reported for intertidal oysters and mussels. Even this more moderate set of responses are still likely to reduce the abundance of M. asperrima and potentially other scallop species in the world's oceans at predicted future pCO2 levels.

The effects of growth phase and salinity on the hydrogen isotopic composition of alkenones produced by coastal haptophyte algae

The isotopic fractionation of hydrogen during the biosynthesis of alkenones produced by marine haptophyte algae has been shown to depend on salinity and, as such, the hydrogen isotopic composition of alkenones is emerging as a palaeosalinity proxy. The relationship between fractionation and salinity has previously only been determined during exponential growth, whilst it is not yet known in which growth phases natural haptophyte populations predominantly exist. We have therefore determined the relationship between the fractionation factor, alpha alkenones-water, and salinity for C37 alkenones produced in different growth phases of batch cultures of the major alkenone-producing coastal haptophytes Isochrysis galbana (strain CCMP 1323) and Chrysotila lamellosa (strain CCMP 1307) over a range in salinity from ca. 10 to ca. 35. alpha alkenones-water was similar in both species, ranging over 0.841-0.900 for I. galbana and 0.838-0.865 for C. lamellosa. A strong (0.85 <= R**2 <= 0.97; p < 0.0001) relationship between salinity and fractionation factor was observed in both species at all growth phases investigated. This suggests that alkenone dD has the potential to be used as a salinity proxy in coastal areas where haptophyte communities are dominated by these coastal species. However, there was a marked difference in the sensitivity of alpha alkenones-water to salinity between different growth phases: in the exponential growth phase of I. galbana, alpha alkenones-water increased by 0.0019 per salinity unit (S 1), but was less sensitive at 0.0010 S 1 and 0.0008 S 1 during the stationary and decline phases, respectively. Similarly, in C. lamellosa alpha alkenones-water increased by 0.0010 S 1 in the early stationary phase and by 0.0008 S 1 during the late stationary phase. Assuming the shift in sensitivity of alpha alkenones-water to salinity observed at the end of exponential growth in I. galbana is similar in other alkenone-producing species, the predominant growth phase of natural populations of haptophytes will affect the sensitivity of the alkenone salinity proxy. The proxy is likely to be most sensitive to salinity when alkenones are produced in a state similar to exponential growth.

Growth dynamics and yield of melon as influenced by nitrogen fertilizer

Nitrogen (N) is an important nutrient for melon (Cucumis melo L.) production. However there is scanty information about the amount necessary to maintain an appropriate balance between growth and yield. Melon vegetative organs must develop sufficiently to intercept light and accumulate water and nutrients but it is also important to obtain a large reproductive-vegetative dry weight ratio to maximize the fruit yield. We evaluated the influence of different N amounts on the growth, production of dry matter and fruit yield of a melon ‘Piel de sapo’ type. A three-year field experiment was carried out from May to September. Melons were subjected to an irrigation depth of 100% crop evapotranspiration and to 11 N fertilization rates, ranging 11 to 393 kg ha –1 in the three years. The dry matter production of leaves and stems increased as the N amount increased. The dry matter of the whole plant was affected similarly, while the fruit dry matter decreased as the N amount was increased above 112, 93 and 95 kg ha –1 , in 2005, 2006 and 2007, respectively. The maximum Leaf Area Index (LAI), 3.1, was obtained at 393 kg ha –1 of N. The lowest N supply reduced the fruit yield by 21%, while the highest increased the vegetative growth, LAI and Leaf Area Duration (LAD), but reduced yield by 24% relative to the N93 treatment. Excessive applications of N increase vegetative growth at the expense of reproductive growth. For this melon type, rates about 90-100 kg ha –1 of N are sufficient for adequate plant growth, development and maximum production. To obtain fruit yield close to the maximum, the leaf N concentration at the end of the crop cycle should be higher than 19.5 g kg –1

Genomic analyses of flowering transition and inflorescence development in grapevine = Análisis genómicos de la transición floral y del desarrollo de la inflorescencia en la vid

The general objective of this work is to analyze the regulatory processes underlying flowering transition and inflorescence and flower development in grapevine. Most of these crucial developmental events take place within buds growing during two seasons in two consecutive years. During the first season, the shoot apical meristem within the bud differentiates all the basic elements of the shoot including flowering transition in lateral primordia and development of inflorescence primordia. These events practically end with bud dormancy. The second season, buds resume shoot growth associated to flower formation and development. In grapevine, the lateral meristems can give rise either to tendril or inflorescence primordia that are homologous organs. With this purpose, we performed global transcriptome analyses along the bud annual cycle and during inflorescence and tendril development. In addition, we approach the genomic analysis of the MIKC type MADS-box gene family in grapevine to identify all its members and assign them putative biological functions. Regarding buds developmental cycle, the results indicate that the main factors explaining the global gene expression differences were the processes of bud dormancy and active growth as well as stress responses. Non dormant buds exhibited up-regulation in functional categories typical of actively proliferating and growing cells (photosynthesis, cell cycle regulation, chromatin assembly) whereas in dormant ones the main functional categories up-regulated were associated to stress response pathways together with transcripts related to starch catabolism. Major transcriptional changes during the dormancy period were associated to the para/endodormancy, endo/ecodormancy and ecodormancy/bud break transitions. Global transcriptional analyses along tendril and inflorescence development suggested that these two homologous organs share a common transcriptional program related to cell proliferation functions. Both structures showed a progressive decrease in the expression of categories such as cell-cycle, auxin metabolism/signaling, DNA metabolism, chromatin assembly and a cluster of five transcripts belonging to the GROWTH-REGULATING FACTOR (GRF) transcription factor family, that are known to control cell proliferation in other species and determine the size of lateral organs. However, they also showed organ specific transcriptional programs that can be related to their differential organ structure and function. Tendrils showed higher transcription of genes related to photosynthesis, hormone signaling and secondary metabolism than inflorescences, while inflorescences have higher transcriptional activity for genes encoding transcription factors (especially those belonging to the MADS-box gene family). Further analysis along inflorescence development evidenced the relevance of additional functions likely related to processes of flower development such as fatty acid and lipid metabolism, jasmonate signaling and oxylipin biosynthesis. The transcriptional analyses performed highlighted the relevance of several groups of transcriptional regulators in the developmental processes studied. The expression profiles along bud development revealed significant differences for some MADS-box subfamilies in relation to other plant species, like the members of the FLC and SVP subfamilies suggesting new roles for these groups in grapevine. In this way, it was found that VvFLC2 and VvAGL15.1 could participate, together with some members of the SPL-L family, in dormancy regulation, as was shown for some of them in other woody plants. Similarly, the expression patterns of the VvFLC1, VvFUL, VvSOC1.1 (together with VvFT, VvMFT1 and VFL) genes could indicate that they play a role in flowering transition in grapevine, in parallel to their roles in other plant systems. The expression levels of VFL, the grapevine LEAFY homolog, could be crucial to specify the development of inflorescence and flower meristems instead of tendril meristems. MADS-box genes VvAP3.1 and 2, VvPI, VvAG1 and 3, VvSEP1-4, as well as VvBS1 and 2 are likely associated with the events of flower meristems and flower organs differentiation, while VvAP1 and VvFUL-L (together with VvSOC1.1, VvAGL6.2) could be involved on tendril development given their expression patterns. In addition, the biological function ofVvAP1 and VvTFL1A was analyzed using a gene silencing approach in transgenic grapevine plants. Our preliminary results suggested a possible role for both genes in the initiation and differentiation of tendrils. Finally, the genomic analysis of the MADS-box gene family in grapevine revealed differential features regarding number and expression pattern of genes putatively involved in the flowering transition process as compared to those involved in the specification of flower and fruit organ identity. Altogether, the results obtained allow identifying putative candidate genes and pathways regulating grapevine reproductive developmental processes paving the way to future experiments demonstrating specific gene biological functions. RESUMEN El objetivo general de este trabajo es analizar los procesos regulatorios subyacentes a la inducción floral así como al desarrollo de la inflorescencia y la flor en la vid. La mayor parte de estos eventos cruciales tienen lugar en las yemas a lo largo de dos estaciones de crecimiento consecutivas. Durante la primera estación, el meristemo apical contenido en la yema diferencia los elementos básicos del pámpano, lo cual incluye la inducción de la floración en los meristemos laterales y el subsiguiente desarrollo de primordios de inflorescencia. Estos procesos prácticamente cesan con la entrada en dormición de la yema. En la segunda estación, se reanuda el crecimiento del pámpano acompañado por la formación y desarrollo de las flores. En la vid, los meristemos laterales pueden dar lugar a primordios de inflorescencia o de zarcillo que son considerados órganos homólogos. Con este objetivo llevamos a cabo un estudio a nivel del transcriptoma de la yema a lo largo de su ciclo anual, así como a lo largo del desarrollo de la inflorescencia y del zarcillo. Además realizamos un análisis genómico de la familia MADS de factores transcripcionales (concretamente aquellos del tipo MIKC) para identificar todos sus miembros y tratar de asignarles posibles funciones biológicas. En cuanto al ciclo de desarrollo de la yema, los resultados indican que los principales factores que explican las diferencias globales en la expresión génica fueron los procesos de dormición de la yema y el crecimiento activo junto con las respuestas a diversos tipos de estrés. Las yemas no durmientes mostraron un incremento en la expresión de genes contenidos en categorías funcionales típicas de células en proliferación y crecimiento activo (como fotosíntesis, regulación del ciclo celular, ensamblaje de cromatina), mientras que en las yemas durmientes, las principales categorías funcionales activadas estaban asociadas a respuestas a estrés, así como con el catabolismo de almidón. Los mayores cambios observados a nivel de transcriptoma en la yema coincidieron con las transiciones de para/endodormición, endo/ecodormición y ecodormición/brotación. Los análisis transcripcionales globales a lo largo del desarrollo del zarcillo y de la inflorescencia sugirieron que estos dos órganos homólogos comparten un programa transcripcional común, relacionado con funciones de proliferación celular. Ambas estructuras mostraron un descenso progresivo en la expresión de genes pertenecientes a categorías funcionales como regulación del ciclo celular, metabolismo/señalización por auxinas, metabolismo de ADN, ensamblaje de cromatina y un grupo de cinco tránscritos pertenecientes a la familia de factores transcripcionales GROWTH-REGULATING FACTOR (GRF), que han sido asociados con el control de la proliferación celular y en determinar el tamaño de los órganos laterales en otras especies. Sin embargo, también pusieron de manifiesto programas transcripcionales que podrían estar relacionados con la diferente estructura y función de dichos órganos. Los zarcillos mostraron mayor actividad transcripcional de genes relacionados con fotosíntesis, señalización hormonal y metabolismo secundario que las inflorescencias, mientras que éstas presentaron mayor actividad transcripcional de genes codificantes de factores de transcripción (especialmente los pertenecientes a la familia MADS-box). Análisis adicionales a lo largo del desarrollo de la inflorescencia evidenciaron la relevancia de otras funciones posiblemente relacionadas con el desarrollo floral, como el metabolismo de lípidos y ácidos grasos, la señalización mediada por jasmonato y la biosíntesis de oxilipinas. Los análisis transcripcionales llevados a cabo pusieron de manifiesto la relevancia de varios grupos de factores transcripcionales en los procesos estudiados. Los perfiles de expresión estudiados a lo largo del desarrollo de la yema mostraron diferencias significativas en algunas de las subfamilias de genes MADS con respecto a otras especies vegetales, como las observadas en los miembros de las subfamilias FLC y SVP, lo cual sugiere que podrían desempeñar nuevas funciones en la vid. En este sentido, se encontró que los genes VvFLC2 y VvAGL15.1 podrían participar, junto con algunos miembros de la familia SPL-L, en la regulación de la dormición. De un modo similar, los patrones de expresión de los genes VvFLC1, VvFUL, VvSOC1.1 (junto con VvFT, VvMFT1 y VFL) podría indicar que desempeñan un papel en la regulación de la inducción de la floración en la vid, como se ha observado en otros sistemas vegetales. Los niveles de expresión de VFL, el homólogo en vid del gen LEAFY de A. thaliana podrían ser cruciales para la especificación del desarrollo de meristemos de inflorescencia y flor en lugar de meristemos de zarcillo. Los genes VvAP3.1 y 2, VvPI, VvAG1 y 3, VvSEP1-4, así como VvBS1 y 2 parecen estar asociados con los eventos de diferenciación de meristemos y órganos florales, mientras que VvAP1 y VvFUL-L (junto con VvSOC1.1 y VvAGL6.2) podrían estar implicados en el desarrollo del zarcillo dados sus patrones de expresión. Adicionalmente, se analizó la función biológica de los genes VvAP1 y VvTFL1A por medio de una estrategia de silenciamiento génico. Los datos preliminares sugieren un posible papel para ambos genes en la iniciación y diferenciación de los zarcillos. Finalmente, el análisis genómico de la familia MADS en vid evidenció diferencias con respecto a otras especies vegetales en cuanto a número de miembros y patrón de expresión en genes supuestamente implicados en la inducción de la floración, en comparación con aquellos relacionados con la especificación de identidad de órganos florales y desarrollo del fruto. En conjunto, los resultados obtenidos han permitido identificar posibles rutas y genes candidatos a participar en la regulación de los procesos de desarrollo reproductivo de la vid, sentando las bases de futuros experimentos encaminados a conocer la funciones biológicas de genes específicos.

Infrastructure Finance in Developing Countries by State and Multilateral Development Banks

Infrastructure concession is an alternative widely used by governments to increase investment. In the case of the road sector, the main characteristics of the concessions are: long-term projects, high investments in the early years of the contract and high risks. A viability analysis must be carried out for each concession and consider the characteristics of the project. When the infrastructure is located in a developing country, political and market growth uncertainties should be add in the concession project analysis, as well as economic instability, because they present greater risks. This paper is an analysis of state bank participation in road infrastructure finance in developing countries. For this purpose, we studied road infrastructure financing and its associated risks, and also the features of developing countries. Furthermore, we considered the issue of state banks and multilateral development banks that perform an important role by offering better credit lines than the private banks, in terms of cost, interest and grace period. Based on this study, we analyzed the Brazilian Development Bank - BNDES – and their credit supply to road infrastructure concessions. The results show that BNDES is the main financing agent for long-term investment in the sector, offering loans with low interest rates in Brazilian currency. From this research we argue that a single state bank should not alone support the increasing demand for finance in Brazil. Therefore, we conclude that there is a need to expand the supply of credit in Brazil, by strengthening private banks in the long-term lending market.

Requirement of STAT5b for sexual dimorphism of body growth rates and liver gene expression

The signal transducer and activator of transcription, STAT5b, has been implicated in signal transduction pathways for a number of cytokines and growth factors, including growth hormone (GH). Pulsatile but not continuous GH exposure activates liver STAT5b by tyrosine phosphorylation, leading to dimerization, nuclear translocation, and transcriptional activation of the STAT, which is proposed to play a key role in regulating the sexual dimorphism of liver gene expression induced by pulsatile plasma GH. We have evaluated the importance of STAT5b for the physiological effects of GH pulses using a mouse gene knockout model. STAT5b gene disruption led to a major loss of multiple, sexually differentiated responses associated with the sexually dimorphic pattern of pituitary GH secretion. Male-characteristic body growth rates and male-specific liver gene expression were decreased to wild-type female levels in STAT5b−/− males, while female-predominant liver gene products were increased to a level intermediate between wild-type male and female levels. Although these responses are similar to those observed in GH-deficient Little mice, STAT5b−/− mice are not GH-deficient, suggesting that they may be GH pulse-resistant. Indeed, the dwarfism, elevated plasma GH, low plasma insulin-like growth factor I, and development of obesity seen in STAT5b−/− mice are all characteristics of Laron-type dwarfism, a human GH-resistance disease generally associated with a defective GH receptor. The requirement of STAT5b to maintain sexual dimorphism of body growth rates and liver gene expression suggests that STAT5b may be the major, if not the sole, STAT protein that mediates the sexually dimorphic effects of GH pulses in liver and perhaps other target tissues. STAT5b thus has unique physiological functions for which, surprisingly, the highly homologous STAT5a is unable to substitute.

Regulation of transforming growth factor β- and activin-induced transcription by mammalian Mad proteins

Members of the transforming growth factor β (TGF-β) superfamily are involved in diverse physiological activities including development, tissue repair, hormone regulation, bone formation, cell growth, and differentiation. At the cellular level, these functions are initiated by the interaction of ligands with specific transmembrane receptors with intrinsic serine/threonine kinase activity. The signaling pathway that links receptor activation to the transcriptional regulation of the target genes is largely unknown. Recent work in Drosophila and Xenopus signaling suggested that Mad (Mothers against dpp) functions downstream of the receptors of the TGF-β family. Mammalian Mad1 has been reported to respond to bone morphogenetic protein (BMP), but not to TGF-β or activin. We report here the cloning and functional studies of a novel mammalian Mad molecule, Mad3, as well as a rat Mad1 homologue. Overexpression of Mad3 in a variety of cells stimulated basal transcriptional activity of the TGF-β/activin-responsive reporter construct, p3TP-Lux. Furthermore, expression of Mad3 could potentiate the TGF-β- and activin-induced transcriptional stimulation of p3TP-Lux. By contrast, overexpression of Mad1 inhibited the basal as well as the TGF-β/activin induced p3TP-Lux activity. These findings, therefore, support the hypothesis that Mad3 may serve as a mediator linking TGF-β/activin receptors to transcriptional regulation.

The role of thyroid hormone in zebrafish and axolotl development

Exogenous thyroid hormone (TH) induces premature differentiation of the zebrafish pectoral fins, which are analogous to the forelimbs of tetrapods. It accelerates the growth of the pelvic fins but not precociously. Goitrogens, which are chemical inhibitors of TH synthesis by the thyroid gland, inhibit the transition from larva to juvenile fish including the formation of scales, and pigment pattern; they stunt the growth of both pectoral and pelvic paired fins. Inhibition by goitrogens is rescued by the simultaneous addition of thyroxine. The effect of adding TH to the rearing water of the postembryonic Mexican axolotl was reinvestigated under conditions that permit continued growth and development. In addition to morphological changes that have been described, TH greatly stimulates axolotl limb growth causing the resulting larva to be proportioned as an adult in about two months. This study extends the known evolutionary relatedness of tetrapod limbs and fish fins to include the TH stimulation of salamander limb and zebrafish fin growth, and suggests that TH is required to complete the life cycle of a typical bony fish and a salamander at the same developmental stage that it controls anuran and flounder metamorphosis.

Association of Smads with lymphoid enhancer binding factor 1/T cell-specific factor mediates cooperative signaling by the transforming growth factor-β and Wnt pathways

The transforming growth factor-β (TGFβ) and Wnt/wingless pathways play pivotal roles in tissue specification during development. Activation of Smads, the effectors of TGFβ superfamily signals, results in Smad translocation from the cytoplasm into the nucleus where they act as transcriptional comodulators to regulate target gene expression. Wnt/wingless signals are mediated by the DNA-binding HMG box transcription factors lymphoid enhancer binding factor 1/T cell-specific factor (LEF1/TCF) and their coactivator β-catenin. Herein, we show that Smad3 physically interacts with the HMG box domain of LEF1 and that TGFβ and Wnt pathways synergize to activate transcription of the Xenopus homeobox gene twin (Xtwn). Disruption of specific Smad and LEF1/TCF DNA-binding sites in the promoter abrogates synergistic activation of the promoter. Consistent with this observation, introduction of Smad sites into a TGFβ-insensitive LEF1/TCF target gene confers cooperative TGFβ and Wnt responsiveness to the promoter. Furthermore, we demonstrate that TGFβ-dependent activation of LEF1/TCF target genes can occur in the absence of β-catenin binding to LEF1/TCF and requires both Smad and LEF1/TCF DNA-binding sites in the Xtwn promoter. Thus, our results show that TGFβ and Wnt signaling pathways can independently or cooperatively regulate LEF1/TCF target genes and suggest a model for how these pathways can synergistically activate target genes.

Ecological approaches and the development of “truly integrated” pest management

Recent predictions of growth in human populations and food supply suggest that there will be a need to substantially increase food production in the near future. One possible approach to meeting this demand, at least in part, is the control of pests and diseases, which currently cause a 30–40% loss in available crop production. In recent years, strategies for controlling pests and diseases have tended to focus on short-term, single-technology interventions, particularly chemical pesticides. This model frequently applies even where so-called integrated pest management strategies are used because in reality, these often are dominated by single technologies (e.g., biocontrol, host plant resistance, or biopesticides) that are used as replacements for chemicals. Very little attention is given to the interaction or compatibility of the different technologies used. Unfortunately, evidence suggests that such approaches rarely yield satisfactory results and are unlikely to provide sustainable pest control solutions for the future. Drawing on two case histories, this paper demonstrates that by increasing our basic understanding of how individual pest control technologies act and interact, new opportunities for improving pest control can be revealed. This approach stresses the need to break away from the existing single-technology, pesticide-dominated paradigm and to adopt a more ecological approach built around a fundamental understanding of population biology at the local farm level and the true integration of renewable technologies such as host plant resistance and natural biological control, which are available to even the most resource-poor farmers.

Essential role for mammalian copper transporter Ctr1 in copper homeostasis and embryonic development

The trace metal copper (Cu) plays an essential role in biology as a cofactor for many enzymes that include Cu, Zn superoxide dismutase, cytochrome oxidase, ceruloplasmin, lysyl oxidase, and dopamine β-hydroxylase. Consequently, Cu transport at the cell surface and the delivery of Cu to intracellular compartments are critical events for a wide variety of biological processes. The components that orchestrate intracellular Cu trafficking and their roles in Cu homeostasis have been elucidated by the studies of model microorganisms and by the characterizations of molecular basis of Cu-related genetic diseases, including Menkes disease and Wilson disease. However, little is known about the mechanisms for Cu uptake at the plasma membrane and the consequences of defects in this process in mammals. Here, we show that the mouse Ctr1 gene encodes a component of the Cu transport machinery and that mice heterozygous for Ctr1 exhibit tissue-specific defects in copper accumulation and in the activities of copper-dependent enzymes. Mice completely deficient for Ctr1 exhibit profound growth and developmental defects and die in utero in mid-gestation. These results demonstrate a crucial role for Cu acquisition through the Ctr1 transporter for mammalian Cu homeostasis and embryonic development.