Melanin is crucial for growth of the black yeast Hortaea werneckii in its natural hypersaline environment

Melanin has an important role in the ability of fungi to survive extreme conditions, like the high NaCl concentrations that are typical of hypersaline environments. The black fungus Hortaea werneckii that has been isolated from such environments has 1,8-dihydroxynaphthalene-melanin incorporated into the cell wall, which minimises the loss of glycerol at low NaCl concentrations. To further explore the role of melanin in the extremely halotolerant character of H. werneckii, we studied the effects of several melanin biosynthesis inhibitors on its growth, pigmentation and cell morphology. The most potent inhibitors were a 2,3-dihydrobenzofuran derivative and tricyclazole, which restricted the growth of H. werneckii on high-salinity media, as shown by growth curves and plate-drop assays. These inhibitors promoted release of the pigments from the H. werneckii cell surface and changed the medium colour. Inhibitor-treated H. werneckii cells exposed to high salinity showed both decreased and increased cell lengths. We speculate that this absence of melanin perturbs the integrity of the cell wall in H. werneckii, which affects its cell division and exposes it to the harmful effects of high NaCl concentrations. Surprisingly, melanin had no effect on H. werneckii survival under H₂O₂ oxidative stress.     

E-cadherin roles in animal biology: A perspective on thyroid hormone-influence

The establishment, remodeling and maintenance of tissular architecture during animal development, and even across juvenile to adult life, are deeply regulated by a delicate interplay of extracellular signals, cell membrane receptors and intracellular signal messengers. It is well known that cell adhesion molecules (cell-cell and cell-extracellular matrix) play a critical role in these processes. Particularly, adherens junctions (AJs) mediated by E-cadherin and catenins determine cell-cell contact survival and epithelia function. Consequently, this review seeks to encompass the complex and prolific knowledge about E-cadherin roles during physiological and pathological states, particularly focusing on the influence exerted by the thyroid hormone (TH).     

Enantioselective Ethylation of Various Aldehydes Catalyzed by Readily Accessible Chiral Diols

Four chiral C₂‐symmetric diols were synthesized in a straightforward three‐step reaction and demonstrated excellent enantioselectivities and good overall yields. Their catalytic activities were examined via the addition of diethylzinc to various aldehydes. The enantioselective addition of diethylzinc to 2‐methoxybenzaldehyde gave the corresponding chiral secondary alcohol with high yields (up to 95%) and moderate to good enantiomeric excess (up to 88%). All synthesized ligands were evaluated in the addition of diethylzinc to various aldehydes in the presence of an additional metal such as Ti(IV) complexes. Chirality 28:593–598, 2016. © 2016 Wiley Periodicals, Inc.     

Relative DNA content in diploid,polyploid, and multiploid species of <Emphasis Type="Italic">Paspalum</Emphasis> (Poaceae) with relation to reproductive mode and taxonomy

It is generally accepted that polyploids have downsized basic genomes rather than additive values with respect to their related diploids. Changes in genome size have been reported in correlation with several biological characteristics. About 75 % of around 350 species recognized for Paspalum (Poaceae) are polyploid and most polyploids are apomictic. Multiploid species are common with most of them bearing sexual diploid and apomictic tetraploid or other ploidy levels. DNA content in the embryo and the endosperm was measured by flow cytometry in a seed-by-seed analysis of 47 species including 77 different entities. The relative DNA content of the embryo informed the genome size of the accession while the embryo:endosperm ratio of DNA content revealed its reproductive mode. The genome sizes (2C-value) varied from 0.5 to 6.5 pg and for 29 species were measured for the first time. Flow cytometry provided new information on the reproductive mode for 12 species and one botanical variety and supplied new data for 10 species concerning cytotypes reported for the first time. There was no significant difference between the mean basic genome sizes (1Cx-values) of 32 sexual and 45 apomictic entities. Seventeen entities were diploid and 60 were polyploids with different degrees. There were no clear patterns of changes in 1Cx-values due to polyploidy or reproductive systems, and the existing variations are in concordance with subgeneric taxonomical grouping.     

Meaningful traits for grouping plant species across arid ecosystems

Grouping species may provide some degree of simplification to understand the ecological function of plants on key ecosystem processes. We asked whether groups of plant species based on morpho-chemical traits associated with plant persistence and stress/disturbance resistance reflect dominant plant growth forms in arid ecosystems. We selected twelve sites across an aridity gradient in northern Patagonia. At each site, we identified modal size plants of each dominant species and assessed specific leaf area (SLA), plant height, seed mass, N and soluble phenol concentration in green and senesced leaves at each plant. Plant species were grouped according with plant growth forms (perennial grasses, evergreen shrubs and deciduous shrubs) and plant morphological and/or chemical traits using cluster analysis. We calculated mean values of each plant trait for each species group and plant growth form. Plant growth forms significantly differed among them in most of the morpho-chemical traits. Evergreen shrubs were tall plants with the highest seed mass and soluble phenols in leaves, deciduous shrubs were also tall plants with high SLA and the highest N in leaves, and perennial grasses were short plants with high SLA and low concentration of N and soluble phenols in leaves. Grouping species by the combination of morpho-chemical traits yielded 4 groups in which species from one growth form prevailed. These species groups differed in soluble phenol concentration in senesced leaves and plant height. These traits were highly correlated. We concluded that (1) plant height is a relevant synthetic variable, (2) growth forms adequately summarize ecological strategies of species in arid ecosystems, and (3) the inclusion of plant morphological and chemical traits related to defenses against environmental stresses and herbivory enhanced the potential of species grouping, particularly within shrubby growth forms.     

The diet of the Antarctic fur seal<Emphasis Type="Italic"> Arctocephalus gazella</Emphasis> at Harmony Point,South Shetland Islands: evidence of opportunistic foraging on penguins?

The analysis of 523 scats collected at Harmony Point, Nelson Island, South Shetland Islands, from January to March in 2001 and 2002, indicated that the diet of non-breeding male Antarctic fur seals Arctocephalus gazella was diverse and composed of both pelagic and benthic-demersal prey. Overall, the Antarctic krill Euphausia superba and fish were the most frequent and numerous prey, followed by penguins, cephalopods (mainly squid) and gastropods. Myctophids represented 86.5% and 65.8% of the fish mass in 2001 and 2002 respectively, with Gymnoscopelus nicholsi being the main prey. Interestingly, penguin remains were present in 39.0% and 31.9% of the samples in 2001 and 2002, respectively and these birds were the main prey by reconstituted mass (74.0% and 76.1% in both seasons). The occurrence of penguins in the diet of A. gazella at Harmony Point is discussed in terms of the foraging strategy employed by seals and the temporal availability of prey.     

<Emphasis Type="Italic">Gloeocapsopsis aurea</Emphasis>, a new subaerophytic cyanobacterium from maritime Antarctica

The cyanobacterial flora of maritime Antarctica appears to contain many endemic species and only few cosmopolitan or wider-distributed taxa. Several morphospecies that have been erroneously identified in the past following available keys from temperate or tropical zones belong in fact to little-known and poorly described Antarctic cyanobacteria. Here we describe the taxonomy of one such example, the colonial species Gloeocapsopsis aurea . This cyanobacterium produces irregular, packet-like colonies that form black mats, films and crusts. Based on analysis of algal samples from Punta Cierva (Antarctic Peninsula) and King George Island (South Shetland Islands), this taxon is widely distributed in coastal, deglaciated areas of the maritime Antarctic. It is an important, often dominating, ecotype, mostly colonising irrigated rocks but also found in a variety of other aquatic and semi-aquatic habitats under a wide range of conductivities, pH and nutrient regimes.     

Enzymatic determination of zinc in vegetables using apocarbonic anhydrase

A new enzymatic method has been developed to determine trace amounts of Zn2+ in vegetables. The basis of the method is that apocarbonic anhydrase regains its activity in proportion to the concentration of Zn2+ present in solution. Bovine carbonic anhydrase was purified from erythrocyte haemolysate by affinity chromatography and the bound Zn2+ removed by dialysis of purified enzyme against a solution of pyridine-2, 6-dicarboxylic acid. Pure (100%) apoenzyme was obtained. The concentration of Zn2+ in vegetable samples was determined using the enzymatic method and by atomic absorption spectroscopy. Determinations made using the two methods were not significantly different one from another.