Novel Players in the Integrin Signaling Orchestra: TCPTP and MDGI

Metastases are the major cause of cancer deaths. Tumor cell dissemination from the primary tumor utilizes dysregulated cellular adhesion and upregulated proteolytic degradation of the extracellular matrix for progeny formation in distant organs. Integrins are transmembrane adhesive receptors mediating cellcell and cellmatrix interactions that are crucial for regulating cell migration, invasion, proliferation, and survival. Consequently, increased integrin activity is associated with augmented migration and invasion capacity in several cancer types. Heterodimeric integrins consist of an alpha - and beta-subunit that are held together in a bent conformation when the receptor is inactive, but extension and separation of subdomains is observed during receptor activation. Either inside-out or outside-in activation of receptors is possible through the intracellular molecule binding to an integrin cytoplasmic domain or extracellular ligand association with an integrin ectodomain, respectively. Several regulatory binding partners have been characterized for integrin cytoplasmic beta-domains, but the regulators interacting with the cytoplasmic alpha-domains have remained elusive. In this study, we performed yeast two-hybrid screens to identify novel binding partners for the cytoplasmic integrin alpha-domains. Further examination of two plausible candidates revealed a significant coregulatory role of an integrin alpha-subunit for cellular signaling processes. T-cell protein tyrosine phosphatase (TCPTP) showed a specific interaction with the cytoplasmic tail of integrin alpha1. This association stimulated TCPTP phosphatase activity, leading to negative regulation of epidermal growth factor receptor (EGFR) signaling and diminished anchorage-independent growth. Another candidate, mammary-derived growth inhibitor (MDGI), exhibited binding to several different integrin cytoplasmic alpha-tails through a conserved GFFKR sequence. MDGI overexpression in breast cancer cells altered EGFR trafficking and caused a remarkable accumulation of EGFR in the cytoplasm. We further demonstrated in vivo that MDGI expression induced a novel form of anti-EGFR therapy resistance. Moreover, MDGI binding to α-tails retained integrin in an inactive conformation attenuating integrin-mediated adhesion, migration, and invasion. In agreement with these results, sustained MDGI expression in breast cancer patients correlated with an increased 10-year distant disease-free survival. Taken together, the integrin signaling network is far from a complete view and future work will doubtless broaden our understanding further.

Anatomia de lesões foliares causadas pelo vírus da Mancha Clorótica do Clerodendrum, transmitido pelo ácaro Brevipalpus phoenicis em diferentes espécies

O gênero botânico Clerodendrum pertence à família Lamiaceae e compreende várias espécies ornamentais, Manchas cloróticas e necróticas em folhas de coração-sangrento foram observadas pela primeira vez em um jardim de Piracicaba, SP, associadas à infestação com Brevipalpus phoenicis (Acari: Tenuipalpidae). Exames de secções de tecidos das lesões foliares ao microscópio eletrônico revelaram ocorrência de efeitos citopáticos do tipo nuclear e concluiu-se que os sintomas eram causados por um vírus transmitido por Brevipalpus (VTB), o qual foi designado de mancha clorótica de Clerodendrum (Clerodendrum Chlorotic Spot Virus- ClCSV). O ClCSV é transmitido mecanicamente de coração-sangrento para coração-sangrento. Em ensaios preliminares foi transmitido por B. phoenicis e mecanicamente para várias outras plantas, além da ocorrência de sua disseminação natural por este ácaro para outras espécies. Visando complementar a caracterização do ClCSV foram feitos estudos sobre alterações anatômicas em folhas de plantas infectadas pelo ClCSV. Foram examinadas secções histológicas de folhas sadias e infectadas pelo ClCSV de C. x speciosum e de outras hospedeiras como Hibiscus schizopetalus, Salvia leucantha, Malvaviscus arboreus e Annona muricata. Constatou-se que o ClCSV causa alterações celulares semelhantes nas diferentes hospedeiras e os sintomas causados por este vírus são similares aos causados por outros vírus transmitidos por Brevipalpus como o vírus da leprose dos citros citoplasmático (Citrus Lepros Virus Cytoplasmic- CiLV-C) e nuclear (Citrus Leprosis Virus Nuclear- CiLV-N), mancha anular do cafeeiro (Coffee Ringspot Virus- CoRSV), mancha anular de Solanum violaefolium (Solanum violaefolium Ringspot Virus- SvRSV) e "Orchid Fleck Vírus" (OFV), representadas por hipertrofia e hiperplasia frequentemente acompanhadas de necrose nos tecidos do parênquima paliçádico e lacunoso.

Nuclear Matrix in Apoptotic Cell Death and Cell Proliferation. The role of Nuclear Mitotic Apparatus (NuMA) Protein

The nucleus is a membrane enclosed organelle containing most of the genetic information of the cell in the form of chromatin. The nucleus, which can be divided into many sub-organelles such as the nucleoli, the Cajal bodies and the nuclear lamina, is the site for several essential cellular functions such as the DNA replication and its regulation and most of the RNA synthesis and processing. The nucleus is often affected in disease: the size and the shape of the nucleus, the chromatin distribution and the size of the nucleoli have remained the basis for the grading of several cancers. The maintenance of the vertebrate body shape depends on the skeleton. Similarly, in a smaller context, the shape of the cell and the nucleus are mainly regulated by the cytoskeletal and nucleoskeletal elements. The nuclear matrix, which by definition is a detergent, DNase and salt resistant proteinaceous nuclear structure, has been suggested to form the nucleoskeleton responsible for the nuclear integrity. Nuclear mitotic apparatus protein, NuMA, a component of the nuclear matrix, is better known for its mitotic spindle organizing function. NuMA is one of the nuclear matrix proteins suggested to participate in the maintenance of the nuclear integrity during interphase but its interphase function has not been solved to date. This thesis study concentrated on the role of NuMA and the nuclear matrix as structural and functional components of the interphase nucleus. The first two studies clarified the essential role of caspase-3 in the disintegration of the nuclear structures during apoptosis. The second study also showed NuMA and chromatin to co-elute from cells in significant amounts and the apoptotic cleavage of NuMA was clarified to have an important role in the dissociation of NuMA from the chromatin. The third study concentrated on the interphase function of NuMA showing NuMA depletion to result in cell cycle arrest and the cytoplasmic relocalization of NuMA interaction partner GAS41. We suggest that the relocalization of the transcription factor GAS41 may mediate the cell cycle arrest. Thus, this study has given new aspects in the interactions of NuMA, chromatin and the nuclear matrix.

Ultrastructural characterization of bovine umbilical cord blood cells

The umbilical cord blood (UCB) is an important source of pluripotent stem cells, which motivated researches on ontogeny and transplantation. The morphological characterization of umbilical cord cells is the first step to establish subsequent experiments on these areas. Although some information on humans can be found, no data on UCB is available for bovines. Therefore, this work is the first attempt to conduct an ultrastructural characterization of bovine umbilical cord blood. Blood was collected from the umbilical cord of twenty fetuses by punction of the umbilical vein. Samples were processed for whole leucocytes observation by centrifugation and the buffy coat was collected. Cells were washed and pelleted and prepared according to the standard protocol of the transmission electron microscopy. The presence of cells with morphologic characteristics compatible with the precursors from the erythrocytic, neutrophilic, eosinophilic, basophilic, and lymphocytic lineages was observed. Atypical cells with peculiar morphological features, strongly similar to apoptotic cells, were seen. Bovine neutrophils with three types of cytoplasmic granules were also found in the blood. The ultrastructural characteristics of observed bovine UCB cells where similar to those found in other species, suggesting that bovines could possibly constitute an experimental model for approaches on UCB cells research.

Analyses of the development and glycoproteins present in the ovarian follicles of Poecilia vivipara (Cyprinodontiformes, Poeciliidae)

The morphofunctional aspects of oogenesis of Poecilia vivipara were studied aiming to understand the reproductive biology and development of species with internal fertilization, particularly those belonging to the family Poeciliidae. The stages of gonadal maturation and follicular development were characterized using mesoscopic, histological, histochemical, and lectin cytochemical analyses. Through mesoscopic evaluation the ovarian development was classified in six phases of development: immature, in maturation I, in maturation II, mature I, mature II, and post-spawn. Based on microscopic examination of the ovaries, we identified the presence of oocytes types I and II during the previtellogenic phase and types III, IV, and V during the vitellogenic phase. As oogenesis proceeded the oocyte cytosol increased in volume and presented increased cytoplasmic granule accumulation, characterizing vitellogenesis. The zona radiata (ZR) increased in thickness and complexity, and the follicular epithelium, which was initially thin and consisting of pavimentous cells, in type III oocytes exhibited cubic simple cells. The histochemical and cytochemical analyses revealed alterations in the composition of the molecular structures that form the ovarian follicle throughout the gonadal development. Our study demonstrated differences in the female reproductive system among fish species with internal and external fertilization and we suggest P. vivipara can be used as experimental model to test environmental toxicity.

Decreased expression of cardiac troponin C is associated with cardiac lesions in Amorimia exotropica poisoned cattle

The plants which cause sudden death of cattle in Brazil occupy a leading position for losses in the cattle industry. Amorimia exotropica is one of the plants pertaining to this group. Diagnostic findings in these cases may be inconclusive; further knowledge is necessary. This paper identifies cardiac lesions through anti-cardiac troponin C (cTnC) immunehistochemistry performed in tissues from cattle poisoned after consumption of A.exotropica in southern Brazil. Heart fragments from nine A. exotropica-poisoned cattle were studied immunohistochemically using anti-human cTnC as the primary antibody. In the hearts from all of the poisoned cattle, there was a sharp decrease in the cTnC expression level in the cytoplasm of groups of cardiomyocytes. A significant decrease in anti-cTnC immunoreactivity occurred particularly in degenerated or necrotic cardiomyocytes. Occasional groups of cells showed complete loss of immunolabeling. In the remaining intact cardiomyocytes from poisoned cattle and in cardiomyocytes from six cattle that died from other causes there was intense cytoplasmic staining.

Immunohistochemical study of genital and extragenital forms of canine transmissible venereal tumor in Brazil

Aiming to provide insight and discussing the problems related to the diagnosis and differential diagnosis of canine transmissible venereal tumor (CTVT), especially in its extragenital form, immunohistochemical evaluation was performed and a comparison was established by analysis of the microscopic appearance of 10 genital CTVTs and 13 exclusively extragenital CTVTs previously diagnosed by cytology and histopathology. CTVTs samples were incubated with biotinylated antibodies raised against specific membrane (anti-macrophage) and cytoplasmic antigens (anti-lysozyme, anti-S-100 protein, anti-vimentin and anti-CD18) and subsequently developed using streptavidin-biotin peroxidase and streptavidin-biotin-alkaline phosphatase methods. A strong reactivity with the anti-vimentin antibody was found in 100% of the tumors tested (22/22). No reactivity was found for the anti-lysozyme, anti-macrophage, anti-S-100 protein and anti-CD18. No histopathological or immunoreactivity differences between genital and extragenital CTVTs were found. These findings do not corroborate the hypothesis of histiocytic origin of CTVT (no reactivity to anti-lysozyme, anti-macrophage and anti-CD 18 antibodies). In addition, the antibody panel used is useful to narrow the differential diagnosis for lymphomas, histiocytic tumors, amelanotic melanomas, and poorly differentiated epithelial neoplasias, among others.

Accidental and experimental Closantel intoxication in Uruguayan sheep

Abstract An outbreak of Closantel intoxication in sheep in Uruguay is described. The outbreak occurred in a group of 1300 weaning lambs treated orally with a 10% solution of Closantel. One hundred forty eight lambs showed clinical signs of intoxication and 14 died. The clinical signs included mydriasis, nystagmus, and negative pupillary reflex, bilateral blindness, bump into objects, and lateral movement of the head. No macroscopic lesions were observed. The histological lesions of the retina were cytoplasmic vacuolization in ganglion cells and in cells of the inner and outer nuclear layers with different degrees of atrophy. Vacuolization and axonal degeneration were observed in the optic nerve, with multifocal areas of fibrosis and infiltration by lymphocytes and Gitter cells. To reproduce the intoxication, four sheep were given two, four and 10 times the therapeutic dose of Closantel (0.1g/kg of BW). Only the animals receiving 10 times the recommended dose showed clinical signs. The histological examination of the lesions in experimental sheep showed similar results to those described in the accidental outbreak, except for the absence of optic nerve fibrosis and inflammation, characterizing an acute phase. Axonal myelin sheaths loss, fibroblasts and collagen fibers were observed in the ultrastructural study of the optic nerve of accidental intoxicated animals. The optic nerve of experimentally intoxicated animals had vacuoles that separated the myelin sheaths of axons. To prevent outbreaks it is suggested to weigh the animals before Closantel administration to avoid errors in dose calculation.

Analysis of open CNC architecture for machine tools

The evolution of digital circuit technology, leadind to higher speeds and more reliability allowed the development of machine controllers adapted to new production systems (e.g., Flexible Manufacturing Systems - FMS). Most of the controllers are developed in agreement with the CNC technology of the correspondent machine tool manufacturer. Any alterations or adaptation of their components are not easy to be implemented. The machine designers face up hardware and software restrictions such as lack of interaction among system's elements and impossibility of adding new function. This is due to hardware incompatibility and to software not allowing alterations in the source program. The introduction of open architecture philosophy propitiated the evolution of a new generation of numeric controllers. This brought the conventional CNC technology to the standard IBM - PC microcomputer. As a consequence, the characteristics of the CNC (positioning) and the microcomputer (easy of programming, system configuration, network communication etc) are combined. Some researchers have addressed a flexible structure of software and hardware allowing changes in the hardware basic configuration and all control software levels. In this work, the development of open architecture controllers in the OSACA, OMAC, HOAM-CNC and OSEC architectures is described.

Fluorescence-based imaging of cellular defect in lysinuric protein intolerance (LPI)

Fluoresenssiperusteiset kuvantamismenetelmät lysinurisen proteiini-intoleranssin (LPI) soluhäiriön tutkimuksessa Lysinurinen proteiini-intoleranssi on suomalaiseen tautiperintöön kuuluva autosomaalisesti peit¬tyvästi periytyvä sairaus, jonka aiheuttaa kationisten aminohappojen kuljetushäiriö munuaisten ja ohutsuolen epiteelisolujen basolateraalikalvolla. Aminohappojen kuljetushäiriö johtaa moniin oirei¬siin, kuten kasvuhäiriöön, osteoporoosiin, immuunijärjestelmän häiriöihin, oksenteluun ja runsaspro¬teiinisen ravinnon nauttimisen jälkeiseen hyperammonemiaan. LPI-geeni SLC7A7 (solute carrier family 7 member 7) koodaa y+LAT1 proteiinia, joka on basolateraali¬nen kationisten ja neutraalien aminohappojen kuljettimen kevyt ketju, joka muodostaa heterodimee¬rin raskaan alayksikön 4F2hc:n kanssa. Tällä hetkellä SLC7A7-geenistä tunnetaan yli 50 LPI:n aiheut¬tavaa mutaatiota. Tässä tutkimuksessa erityyppisiä y+LAT1:n LPI-mutaatiota sekä yhdeksän C-terminaalista polypep¬tidiä lyhentävää deleetiota kuvannettiin nisäkässoluissa y+LAT1:n GFP (green fluorescent protein) -fuusioproteiineina. Tulokset vahvistivat muissa soluissa tehdyt havainnot siitä, että 4F2hc on edel¬lytyksenä y+LAT1:n solukalvokuljetukselle, G54V-pistemutantti sijaitsee solukalvolla samoin kuin vil¬lityyppinen proteiini, mutta lukukehystä muuttavia ja proteiinia lyhentäviä mutantteja ei kuljeteta solukalvoon. Lisäksi havaittiin, että poikkeuksena tästä säännöstä ovat y+LAT1-deleetioproteiinit, joista puuttui korkeintaan 50 C-terminaalista aminohappoa. Nämä lyhentyneet kuljettimet sijaitsevat solukalvolla kuten villityyppiset ja LPI-pistemutanttiproteiinit. Dimerisaation osuutta kuljetushäiriön synnyssä tutkittiin käyttämällä fluorescence resonance energy transfer (FRET) menetelmää. Heterodimeerin alayksiköistä kloonattiin ECFP (cyan) ja EYFP (yellow) fuusioproteiinit, joita ilmennettiin nisäkässoluissa, ja FRET mitattiin virtaussytometri-FRET -menetel¬mällä (FACS-FRET). Tutkimuksissa kaikkien mutanttien havaittiin dimerisoituvan yhtä tehokkaasti. Kul¬jetushäiriön syynä ei siten ole alayksiköiden dimerisaation estyminen mutaation seurauksena. Tutkimuksessa havaittiin, että kaikki mutantti-y+LAT1-transfektiot tuottavat vähemmän transfektoi¬tuneita soluja kuin villityyppisen y+LAT1:n transfektiot. Solupopulaatioissa, joihin oli tranfektoitu lu¬kukehystä muuttava tai stop-kodonin tuottava mutaatio havaittiin suurempi kuolleisuus kuin saman näytteen transfektoitumattomissa soluissa, kun taas villityyppistä tai G54V-pistemutanttia tuottavas¬sa solupopulaatiossa oli pienempi kuolleisuus kuin saman näytteen fuusioproteiinia ilmentämättö¬missä soluissa. Tulos osoittaa mutanttiproteiinien erilaiset vaikutukset niitä ilmentäviin soluihin, joko suoraan y+LAT1:n tai 4F2hc:n kautta aiheutuneina. LPIFin SLC7A7 lähetti-RNA:n määrä ei merkittävästi poikennut villityyppisen määrästä fibroblasteissa ja lymfoblasteissa. SLC7A7:n promoottorianalyysissä oli osoitettavissa säätelyalueita geenin 5’ ei-koo¬daavalla alueella sekä ensimmäisten kahden intronin alueella. LPI-taudin tautimekanismin kannalta keskeisin tekijä on kuitenkin aminohappokuljetuksen häiriö, jonka vaikutuksesta näistä aminohapoista riippuvaiset prosessit elimistössä eivät toimi normaalisti. Havaittu virheellinen y+LAT1/4F2hc kuljetuskompleksin sijainti edellyttää lisätutkimuksia sen mahdol¬lisen kliinisen merkityksen selvittämiseksi.

Chromatoid body mediated RNA regulation in mouse male germline

Male germ cell differentiation, spermatogenesis is an exceptional developmental process that produces a massive amount of genetically unique spermatozoa. The complexity of this process along with the technical limitations in the germline research has left many aspects of spermatogenesis poorly understood. Post-meiotic haploid round spermatids possess the most complex transcriptomes of the whole body. Correspondingly, efficient and accurate control mechanisms are necessary to deal with the huge diversity of transcribed RNAs in these cells. The high transcriptional activity in round spermatids is accompanied by the presence of an uncommonly large cytoplasmic ribonucleoprotein granule, called the chromatoid body (CB) that is conjectured to participate in the RNA post-transcriptional regulation. However, very little is known about the possible mechanisms of the CB function. The development of a procedure to isolate CBs from mouse testes was this study’s objective. Anti-MVH immunoprecipitation of cross-linked CBs from a fractionated testicular cell lysate was optimized to yield considerable quantities of pure and intact CBs from mice testes. This protocol produced reliable and reproducible data from the subsequent analysis of CB’s protein and RNA components. We found that the majority of the CB’s proteome consists of RNA-binding proteins that associate functionally with different pathways. We also demonstrated notable localization patterns of one of the CB transient components, SAM68 and showed that its ablation does not change the general composition or structure of the CB. CB-associated RNA analysis revealed a strong accumulation of PIWI-interacting RNAs (piRNAs), mRNAs and long non-coding RNAs (lncRNAs) in the CB. When the CB transcriptome and proteome analysis results were combined, the most pronounced molecular functions in the CB were related to piRNA pathway, RNA post-transcriptional processing and CB structural scaffolding. In addition, we demonstrated that the CB is a target for the main RNA flux from the nucleus throughout all steps of round spermatid development. Moreover, we provided preliminary evidence that those isolated CBs slice target RNAs in vitro in an ATPdependent manner. Altogether, these results make a strong suggestion that the CB functions involve RNA-related and RNA-mediated mechanisms. All the existing data supports the hypothesis that the CB coordinates the highly complex haploid transcriptome during the preparation of the male gametes for fertilization. Thereby, this study provides a fundamental basis for the future functional analyses of ribonucleoprotein granules and offers also important insights into the mechanisms governing male fertility.

Five Baltic Ports Togehter: Forecasts, Trends and Recommendations

The ports of Stockholm, Tallinn, Helsinki, Naantali and Turku play key roles in making the Central Baltic region accessible. Effective, competitive, eco-friendly and safe port procedures and solutions for the transportation of goods are of major importance for trade in the Baltic Sea region. This report presents the most essential results and recommendations of the PENTA project, which focused on how ports could better comprehend and face current and future challenges facing carriage of goods by sea. Each of the four work packages (WPs) of the PENTA project analysed the changes from a different perspective. WP2 focused on traffic flows between the PENTA ports. Its main emphasis was on the ports, shipowners, and logistics companies that are the key parties in freight transport and on the changes affecting the economy of those ports. In WP3 noise as an environmental challenge for ports was investigated and the analysis also shed light on the relationship between the port and the city. In WP4 procedures related to safety, security and administrative procedures were researched. The main emphasis was on identifying the requirements for the harmonisation of those procedures. Collaboration is highlighted throughout this report. In order to prepare for the future, it was found that ports need to respond to growing competition, increasing costs and shifts in customer demand by strengthening their existing partnerships with other actors in the maritime cluster. Cargo and passenger transport are the main sources of income for most ports. Cargo traffic between the PENTA ports is expected to grow steadily in the future and the outlook for passenger traffic is positive. However, to prepare for the future, ports should not only secure the core activities which generate revenue but also seek alternative ways to make profit. In order to gain more transit traffic, it is suggested that ports conduct a more thorough study of the future requirements for doing business with Russia. The investigation of noise at ports revealed two specific dilemmas that ports cannot solve alone. Firstly, the noise made by vessels and, secondly, the relationship between the port and the surrounding city. Vessels are the most important single noise source in the PENTA ports and also one of the hardest noise sources to handle. Nevertheless, port authorities in Finland and Sweden are held responsible for all noise in the port area, including noise produced by vessels, which is noise the port authority can only influence indirectly. Building housing by waterfront areas close to ports may also initiate disagreements because inhabitants may want quiet areas, whereas port activities always produce some noise from their traffic. The qualitative aspects of the noise question, cooperating with the stakeholders and the communicating of issues related to noise are just as important. We propose that ports should follow the logic of continuous improvement in their noise management. The administrative barriers discussed in this report are mainly caused by differences in international and national legislation, variations in the customs procedures of each country, the incompatibility of the IT systems used in maritime transport, noncompliance with regulations regarding dangerous goods, and difficulties in applying Schengen regulations to vessels from non-EU countries. Improving the situation is out of the hands of the ports to do alone and requires joint action on a variety of levels, including the EU, national authorities and across administrative borders.

Sistemas reprodutivos e polinização em espécies simpátricas de Erythroxylum P. Br. (Erythroxylaceae) do Brasil

Foram investigadas a biologia reprodutiva e a polinização de Erythroxylum campestre St. Hil., E. suberosum St. Hil. e E. tortuosum Mart., ocorrentes na Fazenda Água Limpa, Brasília, DF. Estas espécies são simpátricas, comumente encontradas em cerrados abertos e florescem em média quatro meses por ano. As três espécies são distílicas, isto é, apresentam flores com estiletes longos (longistiladas) e flores com estiletes curtos (brevistiladas), ambas com estames em posicionamentos correspondentes. As flores são similares, pequenas, suavemente perfumadas, de cor creme claro, diurnas, produtoras de néctar (concentração média de sacarose de 20,2%) e duram um dia. Os testes de polinização artificial revelaram que E. suberosum e E. tortuosum são auto-incompatíveis e só formaram frutos de polinizações legítimas. Porém, E. campestre é parcialmente auto-compatível. Em todas as espécies a produção de frutos resultantes de polinização natural, foi maior que aquela de polinizações artificiais. Com exceção de E. campestre, os estudos de microscopia de fluorescência revelaram que os tubos polínicos resultantes de auto-polinização em flores longistiladas foram bloqueados no estilete e em flores brevistiladas no estigma. As três espécies foram indistintamente visitadas por 14 espécies de vespas, 14 de abelhas e duas de dípteros. As vespas dos gêneros Brachygastra, Polistes, Polybia e Pepsis foram consideradas polinizadores efetivos devido à eficiência ao contactarem os estigmas. As abelhas Trigona spinipes e Apis mellifera foram consideradas polinizadores ocasionais.

Pollination ecology of Tabebuia aurea (Manso) Benth. & Hook. and T. ochracea (Cham.) Standl. (Bignoniaceae) in Central Brazil cerrado vegetation

The pollination ecology and breeding systems of Tabebuia aurea (Manso) Benth. & Hook., and T. ochracea (Cham.) Standl. were investigated in an area of cerrado vegetation in the Federal District of Brazil. These species occur sympatrically, flower massively and synchronously for a month, during the dry season (July to September). Both have diurnal anthesis, with similar floral structures, a yellow tubular corolla and produce nectar. Fourteen species of bees visited both Tabebuia species, but, only three Centris species and Bombus morio, were considered potential pollinators, because of their high frequency on the flowers and their efficiency in carrying pollen. Tests on the breeding systems of T. aurea and T. ochracea demonstrated that boths species are self-incompatible, with late-acting self-incompatibility. The proportion of fruit set from cross pollination (T. aurea 17.2% and T. ochracea 12.3%) in both species was low considering the great number of flowers displayed. This suggests a lack of maternal resources for fruit-set. The great amount of seeds per fruit (about 92 in T. aurea and 285 in T. ochracea) may represent an investment of maternal resources allocated on higher quality of fertilized ovules.

Pollination biology in Jacaranda copaia (Aubl.) D. Don. (Bignoniaceae) at the "Floresta Nacional do Tapajós", Central Amazon, Brazil

Jacaranda copaia (Aubl.) D. Don is a pioneer tree widespread in the Brazilian Amazon, usually found colonizing forest gaps and altered areas, and the forest fragment edges. This study investigated aspects of the floral biology, breeding system and pollinators of J. copaia trees. Flowering lasts from August to November, during the low rainfall period extending up to four weeks per tree and 3-4 months for the population as a whole, characterizing a cornucopia flowering pattern. The fruit set ends in the beginning of the rainy season, with wind dispersed winged seeds. Fruit set from open pollination was 1.06% (n = 6,932). Hand pollination using self-pollen (n = 2,099) did not set fruits. Cross-pollination resulted in 6.54% fruit set (n = 2,524), representing six times more than the natural pollination rate (1.06%, n = 6,932). Flowers excluded from insect visitation (automatic self-pollination) did not set fruits (n = 5,372). Pollen tube growth down to ovary was detected under fluorescence microcoscopy in cross-pollinated and selfed pistils. The species is an obligate allogamous plant, with late-acting self-incompatibility system. Approximately 40 species of native bees visited the flowers, but the main pollinators were medium-sized solitary bees as Euglossa and Centris species due to the compatibility between their body sizes with the corolla tube, direct contact with the reproductive structures and high frequency of visits.