Genetic analysis of an osmotic sensitive

Summary The genetic analysis of VY1160 sorbitol dependent, osmotic sensitive yeast mutant led to the identification of three different nuclear recessive mutations. Two of them, designated sorb^- and ts1 are closely linked to one another. The mutation sorb^- determines the lysis, while the mutation tsl increases the ability for lysis of the sorbitol dependent cells. The third mutation ts2 segregates independently from the other two and confers the sensitivity of VY1160 mutant cells towards rifampicin.     

The mechanism of action of Cu2+ on the frog skin.

The mechanism of action of Cu2+ when applied to the external side of the frog skin preparation was investigated. Cu2+ acts most probably on the external barrier of this preparation, since it increases the transport pool of Na+ proportionally to the increase in the short circuit current (Isc). Cu2+ does not open new routes for the Na+ entry since the stimulated Isc is still completely abolished by amiloride. The Isc dependence of Na+ concentration in the external medium is modified by copper, since the Km value increases in addition to changes in V. It is suggested that copper acts at the external barrier Na channels in a way similar to that proposed by Zeiske and Lindemann ((1974) Biochim. Biophys. Acta 352, 323--326) for benzoylimidazole-2 guanidine and benzoylthiazole-2 guanidine and by Dick and Lindemann ((1975) Pflügers Arch. ges. Physiol. 355, R72) for para-chloromercuribenzenosulfonate and para-chloromercuribenzoate.     

First record of anomalous otoliths of Menticirrhus americanus in the South Atlantic

Sagitta otoliths are usually formed of calcium carbonate polymorphs as aragonite. The objective of this study was to verify which carbonate polymorph is predominant in the sagitta otolith of Menticirrhus americanus and check whether this pattern remains in otoliths with morphological alterations. Otoliths of M. americanus were obtained from five sites on the southeast‐south coast of Brazil (São Sebastião (SS) 23°45′S–45°24′O, n = 29; Cananéia‐Iguape Estuarine Complex (CI) 25°02′S–47°54′O, n = 30; Paranaguá Estuarine Complex (PEC) 25°28′S–48°20′O, n = 35; Itapoá (IT) 26°07′S–48°36′O, n = 31; Laguna (LA) 28°28′S–48°46′O, n = 13). The characterization of carbonate polymorphs of otoliths was performed through Raman spectroscopy, a photonic and non‐destructive technique that analyzes molecular vibrations induced by laser. We analyzed 138 pairs of M. americanus otoliths, of which eight otoliths from different pairs presented morphological alterations (SS n = 1, CEP n = 5, IT n = 1, LA n = 1). The Raman spectra show that normal otoliths, that is, without morphological alterations, presented only aragonite in their structure. Among the otoliths that presented morphological alterations, the Raman spectra allowed to identify in six otoliths the deposition of aragonite and in only two otoliths the deposition of vaterite (one specimen of the PEC and one of SS).     

The ecology of a late Visean forest at Catcraig (East Lothian,Scotland) based on multiproxy study of paleosol and root-casts

The Middle Longcraig Limestone (late Visean) at Catcraig, Scotland, is densely covered with large (about 1 m in diameter) hollows, which are surrounded by numerous fossilized roots. The latter represent the positions of tree-sized plants belonging to a fossil forest. This paper aims to reconstruct its ecology based on paleosol properties, size and spatial distribution of root-casts, rooting system morphology and characteristics of coalified plant remnants. The obtained data are consistent with the supposition that the Visean peat wetland forest of Catcraig represents a Cordaitalean dominated community composed of mono-sized, most probably, even-aged giant trees. The peaty paleosol (Histosol) contains pyrite and siderite, indicating reducing and acidic conditions, whilst the abundant presence of gypsum testifies periods of elevated salinity. The adaptation of trees to such conditions is supported by morphologically evident large root mass (typically more than 1000 individual roots per cast). Good preservation of plant tissues in peat, in addition to other paleosol and rooting system characteristics allow us to conclude that the trees occupied seacoast settings or lagoons, which were not permanently flooded.     

Toward an understanding of broad-scale patterns of the habitat suitability of fountain grass (Cenchrus setaceus (Forssk.) Morrone,Poaceae)

Plant Ecology - Understanding the factors contributing to the introduction and spread of invasive species is crucial to help develop management strategies to control and eradicate them in sensitive...