University of the Algarve

About: University of the Algarve is a education organization based out in Faro, Portugal. It is known for research contribution in the topics: Population & Tourism. The organization has 3649 authors who have published 10303 publications receiving 233536 citations.

Simple and rapid RNA extraction from freeze-dried tissue of brown algae and seagrasses

Abstract: An inexpensive and rapid RNA extraction protocol for brown algae and seagrasses is presented, based on homogenization in a simple CTAB buffer and selective precipitation of RNA with lithium chloride. The protocol avoids the use of toxic chaotropic agents and phenol; high concentrations of dithiothreitol are used to inhibit RNase activity and to prevent oxidative cross-linking of nucleic acids by phenolics. A relatively high throughput of about 100 samples in 24 h can be achieved for, for example, Northern analysis. Yields of 50–200 µg g−1 fresh weight are comparable with those obtained for higher plants using commercially available kits. Tests of the extraction procedure demonstrate that high quality, intact RNA can be obtained from a variety of lyophilized brown algal tissues, even after prolonged storage at room temperature. Lyophilization is therefore suggested as an alternative to freezing tissue at −70°C to −80°C. The RNA obtained was used directly in several downstream applications to detect Fucus p...

Habitat continuity and stepping-stone oceanographic distances explain population genetic connectivity of the brown alga Cystoseira amentacea.

Abstract: Effective predictive and management approaches for species occurring in a metapopulation structure require good understanding of interpopulation connectivity. In this study, we ask whether population genetic structure of marine species with fragmented distributions can be predicted by stepping-stone oceanographic transport and habitat continuity, using as model an ecosystem-structuring brown alga, Cystoseira amentacea var. stricta. To answer this question, we analysed the genetic structure and estimated the connectivity of populations along discontinuous rocky habitat patches in southern Italy, using microsatellite markers at multiple scales. In addition, we modelled the effect of rocky habitat continuity and ocean circulation on gene flow by simulating Lagrangian particle dispersal based on ocean surface currents allowing multigenerational stepping-stone dynamics. Populations were highly differentiated, at scales from few metres up to thousands of kilometres. The best possible model fit to explain the genetic results combined current direction, rocky habitat extension and distance along the coast among rocky sites. We conclude that a combination of variable suitable habitat and oceanographic transport is a useful predictor of genetic structure. This relationship provides insight into the mechanisms of dispersal and the role of life-history traits. Our results highlight the importance of spatially explicit modelling of stepping-stone dynamics and oceanographic directional transport coupled with habitat suitability, to better describe and predict marine population structure and differentiation. This study also suggests the appropriate spatial scales for the conservation, restoration and management of species that are increasingly affected by habitat modifications.

Paragangliomas/Pheochromocytomas: Clinically Oriented Genetic Testing

Abstract: Paragangliomas are rare neuroendocrine tumors that arise in the sympathetic or parasympathetic nervous system. Sympathetic paragangliomas are mainly found in the adrenal medulla (designated pheochromocytomas) but may also have a thoracic, abdominal, or pelvic localization. Parasympathetic paragangliomas are generally located at the head or neck. Knowledge concerning the familial forms of paragangliomas has greatly improved in recent years. Additionally to the genes involved in the classical syndromic forms: VHL gene (von Hippel-Lindau), RET gene (Multiple Endocrine Neoplasia type 2), and NF1 gene (Neurofibromatosis type 1), 10 novel genes have so far been implicated in the occurrence of paragangliomas/pheochromocytomas: SDHA, SDHB, SDHC, SDHD, SDHAF2, TMEM127, MAX, EGLN1, HIF2A, and KIF1B. It is currently accepted that about 35% of the paragangliomas cases are due to germline mutations in one of these genes. Furthermore, somatic mutations of RET, VHL, NF1, MAX, HIF2A, and H-RAS can also be detected. The identification of the mutation responsible for the paraganglioma/pheochromocytoma phenotype in a patient may be crucial in determining the treatment and allowing specific follow-up guidelines, ultimately leading to a better prognosis. Herein, we summarize the most relevant aspects regarding the genetics and clinical aspects of the syndromic and nonsyndromic forms of pheochromocytoma/paraganglioma aiming to provide an algorithm for genetic testing.

The reproductive biology of the two-banded sea bream (Diplodus vulgaris) from the southwest coast of Portugal

Abstract: Summary The study of the reproduction of Diplodus vulgaris (Geoff.) as part of a base-line study of the fishery resources of the south-west coast of Portugal, was based on the analysis of the spawning season, gonad maturation, size at maturity, fecundity and hermaphroditism. The spawning season is relatively long, from December to March, with peaks in January and February. No significant differences were found either in the sex ratio (M : F = 1.01) over the year or by size. The size at first maturity (L50) for all sexes and undetermined individuals combined was 18.33 cm total length (TL), with no significant differences between males and females. The estimated L50 is considerably greater than the minimum legal size in Portugal of 15.0 cm. Mean absolute fecundity (Fa) was 131 127 oocytes, ranging from 31 523 to 250 608. The relationship between absolute fecundity and total length (TL) (Fa = 25 398 TL – 484 426) and somatic weight (SW) (Fa = 878.8SW – 71 416) was of the linear type. The mean number of oocytes per gram of somatic weight was 526, ranging from 194 to 887. The reproductive strategy of this species is characterized by a rudimentary hermaphroditism with possible protandry, as evidenced by the existence of individuals in sexual transition.

Dichloro and dimethyl dioxomolybdenum(VI)–diazabutadiene complexes as catalysts for the epoxidation of olefins

Abstract: The dioxomolybdenum(VI) complex [MoO2Cl2{p-tolyl(CH3DAB)}] has been prepared in good yield by reaction of the solvent adduct MoO2Cl2(THF)2 with one equivalent of the bidentate ligand N,N-p-tolyl-2,3-dimethyl-1,4-diazabutadiene. Treatment of the dichloro complex with the Grignard reagent CH3MgCl gives the dimethyl derivative [MoO2(CH3)2{p-tolyl(CH3DAB)}]. The complexes are highly active and selective catalysts for the homogeneous epoxidation of cyclooctene using tert-butyl hydroperoxide (TBHP) as the oxidant. In both cases, the initial activity is ca. 175 mol mol−1Mo h−1 and cyclooctene oxide is obtained quantitatively within 4 h. It was possible to recover the dimethyl complex at the end of the reaction and reuse it in a second run with only a small decrease in activity. The complexes are also active and selective for the epoxidation of other olefins, such as 1-octene, 2-octene, cyclododecene and (R)-(+)-limonene, with TBHP. The catalytic production of cyclooctene oxide was investigated in detail, varying either the reaction temperature or the initial concentrations of substrate, oxidant and catalyst precursor. Kinetic studies show that the catalyst precursor–oxygen donor complex formation is first-order in TBHP and in the metal complex [MoO2Cl2{p-tolyl(CH3DAB)}]. A specific rate of 3.2 mol−1 dm3 s−1 was found for catalyst formation at 25 °C. Activation parameters for this reaction have also been measured (ΔH≠ = 48 ± 3 kJ mol−1, ΔS≠ = −112 ± 10 J mol−1 K−1).