João Pais

The Paleogene and Neogene of Western Iberia (Portugal): A Cenozoic Record in the European Atlantic Domain

The Portuguese mainland, located in western Iberia, represents a key area for understanding the evolution of the European Atlantic margin during the Cenozoic and the establishment of relations with the Mediterranean, in particular through the transition area between those two oceans which is well documented in the Algarve region.

Raunsgaardispermum lusitanicum gen. et sp. nov., a new seed with in situ pollen from the Early Cretaceous (probably Berriasian) of Portugal: Further support for the Bennettitales‐Erdtmanithecales‐Gnetales link

A new genus and species, Raunsgaardispermum lusitanicum, is described from the Bombarral formation, Early Cretaceous (probably Berriasian) of Portugal. The new taxon is based on small well‐preserved, lignitised seeds, about 1.2 – 2.1 mm long and 0.9 – 1.26 mm wide, ovoid to broadly elliptic in outline with a distinct pointed micropylar region. The seed wall is composed by a thin membranous integument extended apically into a long tubular micropyle. The integument is enclosed almost completely by an outer envelope except for a small circular opening for micropylar region. The outer envelope is bivalved and sclerenchymatous, ornamented by narrow longitudinal ridges. Papillae are present apically on the inner surface of the seed envelope adjacent to the micropylar tube. Monocolpate, tectate‐psilate‐punctate pollen grains, about 26 – 29 µm long and 14 – 16 µm wide, were observed in situ in the micropyle of one seed and on the outer surface of several others. The seeds show an interesting character combination of distinct ephedroid seed characters coupled with pollen characters of Bennettitales and Erdtmanithecales and add further evidence to the link between Bennettitales, Erdtmanithecales and Gnetales.

Fossil Kajanthus lusitanicus gen. et sp . nov. from Portugal: Floral evidence for Early Cretaceous Lardizabalaceae (Ranunculales, basal eudicot)

Abstract A new fossil flower, Kajanthus lusitanicus gen. et sp. nov, is described from the Early Cretaceous (late Aptian–early Albian) Chicalhão site near the village of Juncal, western Portugal, based on a single coalified specimen. The flower is small, actinomorphic, trimerous and bisexual, slightly compressed and with floral organs tightly adhering. The perianth is organised in more than two whorls. The inner two whorls consist of six bulky, apparently fleshy parts. The outer perianth whorls consist of narrow parts. There are six stamens, arranged in two whorls. The filaments are thick and anthers tetrasporangiate. The pollen sacs are protruding with extrorse dehiscence. Pollen observed in situ is tricolpate, tectate, finely punctate-perforate, compressed and more or less spherical in polar view with a diameter of about 15 µm. The gynoecium is superior and composed of three free carpels. Non-destructive virtual sectioning of the single flower using synchrotron radiation X-ray tomographic microscopy revealed the presence of several curved ovules in each carpel, arranged in two longitudinal rows on marginal placentae. The character suite of the Kajanthus flower is only found in extant Lardizabalaceae (Ranunculales), where it is particularly close to Sinofranchetia, a monotypic genus that is now endemic to China.

Pliocene flora from S. Pedro da Torre deposits (Minho, NW Portugal)

ABSTRACT This paper deals with the systematic and botanical description of the microfloral elements from the Pliocene S. Pedro da Torre section (NW Portugal) and the description of the palaeoenvironment and palaeoclimate, for use as a correlation attempt with other Pliocene deposits. The S. Pedro da Torre section represents one of the main sites which may help us to understand the vegetation and the paleoenvironment of the Pliocene north-western Iberian Peninsula. Nearly 70 different taxa were indentified (including bryophytes, ferns, gymnosperms and angiosperms), which indicate a palaeowetland setting, dominated by arboreal vegetation that developed under humid and warm climatic conditions.

Erdtmanitheca portucalensis, a new pollen organ from the Early Cretaceous (Aptian–Albian) of Portugal with Eucommiidites-type pollen

Abstract A new lignitised, slightly compressed pollen organ, Erdtmanitheca portucalensis, with affinities to extinct Erdtmanithecales from the Early Cretaceous (Aptian–Albian) of Vale de Água (Lusitanian Basin, western Portugal), is described. The pollen organ is composed of loosely arranged microsporophylls radiating from a central core. The estimated number of microsporophylls is about 100–150. The microsporophylls are sessile and ellipsoidal to barrel-shaped with a flattened or slightly apically depression containing about ten narrow sporangia. The sporangia enclose abundant well-preserved pollen grains of Eucommiidites-type. Pollen grains found in situ are elliptical in equatorial outline, about 16.0–27.2 μm long and 11.9–16.4 μm wide. The main (distal) colpus is long with expanded rounded ends. It is flanked by two subsidiary colpi in an almost equatorial position. The surface of the pollen wall is psilate and occasionally punctate. The ektexine is composed of a distinct tectum, granular infratectal layer and a thin foot layer. The endexine is thick and laminar. The new Early Cretaceous Portuguese pollen-organ is similar in several respects to that of Erdtmanitheca texensis described from the Late Cretaceous of Texas, USA. The new fossil species further documents the importance of the Bennettitales-Erdtmanithecales-Gnetales group in the Early Cretaceous floras of Portugal extending the stratigraphic and geographical distribution of the genus with regard to systematic and phylogenetic significance of the Eucommiidites-producing plants that may have been co-occurring with the Early Cretaceous diversification of angiosperms. It is ascertained that perforate tectum occurs in pollen grains with a well-developed foot layer as well as in pollen grains in which a foot layer is poorly developed or lacking, and that pollen features do not support a separation of the Erdtmanithecales seeds and pollen organs.

Determination of apovincaminic acid in human plasma by high-performance liquid chromatography

An isocratic high-performance liquid chromatographic method is described for the quantitative analysis of low concentrations of apovincaminic acid (AVA) in blood plasma. AVA, interfering plasma components and primidone (used as the internal standard) were separated on a reversed-phase column of LiChrospher 60 RP-Select B (125 mm x 3 mm i.d.; 5 microns) (Merck). A UV-Vis detector was used at a wavelength of 254 nm. Each chromatographic separation was completed in 14 min and the results showed a relative recovery which varied between 95.9 and 116%, a good overall precision (relative standard deviation, 7.00%) and sensitivity over a linear range of 5.00-300 ng ml-1 (R = 0.999) for AVA in plasma. The method was applied to the analysis of plasma samples obtained from healthy subjects treated with one single oral dose of 20 mg of vinpocetine. The results indicate the method to be suitable for pharmacokinetic studies.

Evolution of forest cover in Portugal: A review of the 12th–20th centuries

Portugal’s forests in the 12th century were dominated by the Fagaceae represented by Quercus and Castanea, and several pine species. From the 12th century onwards, forests underwent changes in their management starting with protection and ultimately leading to intense exploitation. The massive naval construction during the maritime expansion (mainly in the 15th–16th centuries) involved felling of approximately 5 million trees mainly Quercus suber, Pinus pinea and other Quercus species. Cumulative fuel-wood consumption of 959 Mm3 during 1300–1854 was attributed to demographic expansion while the deforestation rate during 1636–1854 accounted for a minimum of 72.6% and a maximum of 96% of total forest cover. The volume of timber used in railway sleepers from 1856 onwards might have reached 0.5 Mm3. The last quarter of the 20th century increased the forest cover of Portugal through the World Bank program of Eucalyptus globulus reforestation.

Evolution of Forest Cover in Portugal: From the Miocene to the Present

The transition of the Upper Oligocene throughout the Miocene was characterized by a cooling phase responsible for the extinction of several Palaeotropical taxa and the expansion of Arctotertiary taxa (Abies spp. Alnus spp.). Despite the dominant presence of sub-tropical, and tropical species in the Miocene these species were replaced in the Upper Miocene by large temperate forests of Populus, Salix, Carpinus, Castanea, Quercus , Acer, among others. During the Pliocene a progressive extinction of thermophyllous species and an increase in elements of the Mediterranean flora—Quercus, Olea, Ericaceae and Cistaceae occurred in the Iberian Peninsula. The Pleistocene cooling was responsible for profound changes in the Earths flora and fauna, although the low latitude of the Iberian Peninsula spared several taxa. In Southern Europe some thermophyllous species (Sequoia, Taxodium, Keteleeria) were present until the Gunz glaciation. In Portugal, the forests in the XII century were dominated by plants of the Fagaceae Family (Quercus spp and Castanea spp) but still with the presence of elements from the late Laurisilva. From the XII century onwards, forests underwent changes in their management, from protection until strong exploitation especially due to the maritime expansion and shipbuilding activities (XV and XVI centuries) and from 1636 onwards the demographic pressure. In the last quarter of the XIX century and beginning of the twentieth century afforestation programs were implemented throughout the mainland. In the last half century, industrial private forest (pulp and paper industry) had largely increased the area under Eucalyptus globulus, which reach at present 812,000 ha.

A new species of the spore genus Costatoperforosporites from Early Cretaceous deposits in Portugal and its taxonomic and palaeoenvironmental significance

Abstract A new species of spore, Costatoperforosporites friisiae sp. nov., is described from the Early Cretaceous (late Aptian–early Albian) deposits of Catefica in the Lusitanian Basin, western Portugal. Although the morphology of the muri is clearly of the Cicatricosisporites type, the presence of micropores on these sculptural elements and within the intervening grooves is a particularly distinctive feature and more typical of spores that have been attributed previously to Costatoperforosporites. As a result, this genus is emended not only to accommodate Costatoperforosporites friisiae but also to differentiate it more clearly from other, similar, murornate genera. It is considered to represent the family Anemiaceae. So far, Costatoperforosporites friisiae has only been encountered in the Catefica palynoflora. The presence of many other pteridophyte spores, especially of schizaealean derivation, together with abundant cheirolepidiacean remains at this locality, strongly suggests a warm, moist climate and diverse source vegetation.

Surface active glycosides: Synthesis and toxicity studies

C wall and secreted proteins are the vehicles for the interaction between fungi and their host. Most of these proteins are glycosylated and this posttranslational modification is essential for their localization and function. Although the role for glycoproteins in these interactions has been studied in fungal animal pathogens for many years, almost nothing is known for phytopathogens fungi. Ustilago maydis has raised as an excellent model for the study of plant-pathogen interactions and its relation with the maize plant is one of the systems in which studies can be tackled from both plant and pathogen perspective. In the last years our group is focused on the study of the role for Nand O-glycosylation during the maize infection for this fungus. We have identified many of the proteins involved in both process, demonstrate that Nand O-glycosylation are both essential for virulence and identified mutants in different stages across the infection process. So we have shown that mutants for Pmt4 (O-mannosyltransferase) are not able to form appressorium, a structure required for plant penetration, mutants for Gls1 (glucosidase I) cannot progress into the plant once the plant has been penetrated and Gas2 (glucosidase II b-subunit) mutants are unable to induce plant tumor formation after a defective progression into the plant. By applying in silico analysis we have identified Pmt4 targets which are essential to complete plant infection. Now we are using 2D gel analysis to identify cytoplasmic, secreted and cell wall glycoproteins involved in the infection process.P is a major heparan sulfate (HS) proteoglycan in the arterial wall. Previous studies have localized perlecan to atherosclerotic lesions and its expression correlates with lesion progression. The retention of atherogenic lipoproteins in the arterial wall is an early step in the development of atherosclerosis and this retention is presumably mediated by the ionic interaction between the negatively charged HS and the basic amino acids of apolipoprotein B-100. Perlecan contains a core protein and three HS side chains. Its core protein has five domains (I-V) with disparate structures and domain II is highly homologous to the ligand-binding portion of low-density lipoprotein receptor (LDLR). The functional significance of this domain has been unknown. Here, we show that the perlecan domain II interacts with LDL. Importantly, the interaction largely relies on O-linked glycans that are only present in the secreted domain II. Among the five repeat units of domain II, most of the glycosylation sites are from the second unit, which is highly divergent and rich in serine/threonine but no cysteine residues. Interestingly, most of the glycans are capped by the negatively charged sialic acids, which are critical for LDL binding. We further demonstrate an additive effect of HS and domain II on LDL binding. Unlike LDLR, which directs LDL uptake through endocytosis, this study uncovers a novel feature of the perlecan LDLR-like domain II in receptor-mediated lipoprotein retention, which depends on its glycosylation. Thus, the arterial perlecan glycosylation may provide an attractive non-lipid target to decrease the progression of atherosclerosis.L cancer is currently the leading cause of cancer-related death worldwide, accounting for approximately a third of all cancer diagnoses and related-deaths. Non-small cell lung cancer (NSCLC) represents nearly 80% of lung tumors; the two most common NSCLC histological types are squamous cell carcinoma (SCC) and adenocarcinoma (ADCA). Several diagnosis procedures detecting altered glycosylation have been developed and incorporated as assistant procedures in clinical oncology. The synthesis of mucintype O-glycans is started in a reaction catalyzed by UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts). This is a complex family of enzymes of at least 20 members in humans. We previously found that GALNT13, the gene encoding GalNAc-T13 isoenzyme, is a strong predictor of poor clinical outcome in neuroblastoma patients. In the present study, we evaluated GalNAc-T13 expression in human NSCLC. We produced a monoclonal antibody (MAb T13.5) that was used to assess the expression profile of the GalNAc-T13 protein in a well-defined population of 443 surgically resected NSCLC patients with 7 years of follow-up. We found that ADCAs expressed higher levels of the enzyme than SCCs. GalNAc-T13 expression correlated significantly with worse overall survival in ADCA patients treated with neoadjuvant chemotherapy. These data suggest that GalNAc-T13 could be a novel marker associated to chemoresistance in lung adenocarcinomas.