Variability on morphological and ecological seed traits of Limonium avei (De Not.) Brullo & Erben (Plumbaginaceae)

Limonium avei is an annual species occurring in the salt‐marshes and in limited surfaces of rocky areas around the Mediterranean coasts. Seed lots from five populations of this species, along a latitudinal gradient, were analyzed using an image analysis system to detect differences in seed morphology among populations. Germination requirements at constant (5–25°C) and alternating temperatures (25/10°C), both in light and in darkness, were evaluated for all populations, as well as the effect of the calyx removal on final seed germination and its rate. Morpho‐colorimetric analysis clearly identified seeds from different populations, habitats and substrates without misattributions among them. The calyx slowed the germination process, influencing both final germination and rate with respect to naked seeds. Seeds from all populations germinated with significantly higher percentages in the light, with respect to those incubated in the darkness, and showed rapid germination (time in days to reach 50% of germination: 0.5 days) at the warmer tested temperature (25°C). High germination (>80%) was also detected for seeds of all the investigated populations, except for those from the Apulian region (South Italy, ca. 60%). Our results highlight that L. avei has a high variability in seed morphology, probably habitat induced, and a fast germination response for all populations. Rapid germination may be an adaptive strategy that allows L. avei seeds to take advantage of transient favorable conditions during the germination stage, to ensure seedling establishment under the unpredictable rainfall pattern in the Mediterranean climate.     

Diversity of bacteria and archaea from two shallow marine hydrothermal vents from Vulcano Island

Extremophiles - To obtain new insights into community compositions of hyperthermophilic microorganisms, defined as having optimal growth temperatures of 80 °C and above, sediment and...     

Frequently asked questions about chlorophyll fluorescence,the sequel

Using chlorophyll (Chl) a fluorescence many aspects of the photosynthetic apparatus can be studied, both in vitro and, noninvasively, in vivo. Complementary techniques can help to interpret changes in the Chl a fluorescence kinetics. Kalaji et al. (Photosynth Res 122:121–158, 2014a) addressed several questions about instruments, methods and applications based on Chl a fluorescence. Here, additional Chl a fluorescence-related topics are discussed again in a question and answer format. Examples are the effect of connectivity on photochemical quenching, the correction of F _V /F _M values for PSI fluorescence, the energy partitioning concept, the interpretation of the complementary area, probing the donor side of PSII, the assignment of bands of 77 K fluorescence emission spectra to fluorescence emitters, the relationship between prompt and delayed fluorescence, potential problems when sampling tree canopies, the use of fluorescence parameters in QTL studies, the use of Chl a fluorescence in biosensor applications and the application of neural network approaches for the analysis of fluorescence measurements. The answers draw on knowledge from different Chl a fluorescence analysis domains, yielding in several cases new insights.     

Survival of Vibrio cholerae 01 in common foodstuffs during storage at different temperatures

Survival of Vibrio cholerae El Tor serotype Inaba was examined in pasteurized milk, freshwater fish, raw beef and raw chicken at a variety of temperatures. Both food type and incubation temperature affected survival. At the lowest temperatures, V. cholerae remained viable in meats for up to 90 d at—5°C and 300 d at —25°C. In milk, however, it was not detectable after 34 d at —5°C and 150 d at —25°C. At 7°C it survived 32 d, on average, in milk and only 18–20 d in the other foods. At room temperatures survival periods were shorter, never exceeding 10 d, and it was not detected after 2 d incubation at 35°C in chicken and fish.     

Ultrastructure of the paraphysis in Bufo bufo larvae

A study of the ultrastructure and function of the paraphysis in Bufo bufo larvae was carried out. The structure is a tubular-ramified gland made up of numerous tubules with monolayered epithelial walls surrounded by connective tissue and sinusoids. The epithelial cells secrete glycoprotein to contribute to production of the cephalorachidian fluid. The role of the paraphysis in the transport of fluids and electrolytes from the blood to the cephalorachidian fluid in regulation of ionic and osmotic homeostasis is discussed. © 1994 Wiley-Liss, Inc.     

Study of fumarase activity in non-conventional media. Part II

The hydration of fumarase and the dehydration ofl-malate catalysed by fumarase were investigated in water/methanol and water/formamide one phase systems. The effects of the amount of organic solvent on the maximum velocity (V_max), the Michael is-Menten constant (K_M) and the equilibrium constant (K_eq) were studied for both the reaction media. The denaturing power of both methanol and formamide was observed together with the familiar decrease of the K_M. Fumarase catalysis in water/methanol systems was further investigated by evaporating the organic solvent and evaluating the degree of reversibility of the inactivation. Reversibility of formamide denaturation was also investigated. The effects of phosphate concentration in the reaction medium with different amounts of methanol was investigated following the variation of the kinetic parameters of the hydration reaction. At high concentrations of phosphate an inhibiting effect appeared. Time-dependent denaturation was also investigated and a remarkable instability of fumarase in systems with percentages (v/v) of formamide higher than 10% was observed. 10% formamide proved to be less deactivating than the other non-conventional reaction media so far employed.     

pH dependence of the baker's yeast conversion of 4-benzoyloxy-crotonaldehyde into the 1-benzoate of (2R) 1,2,4-butanetriol

In the baker's yeast mediated conversion of 4-benzoyloxycrotonaldeyde (5) ito the 1-benzoate of (2R) 1,2,4-butanetriol (7) there is a market dependence of the ee values from the pH, nearly racemic materials being obtained over pH 4.6.     

Homologies, analogies, synapomorphies and homoplasies: problems and considerations.

The author discusses, on the evidence of some typical examples, some problems in the assessment of homologies which have surfaced by the integration of ultrastructural and genetic evidences in the assessment of the morphologic and evolutionary significance of structures. He thence considers problems of correct assessment of homologies as true apomorphic rather than homoplastic traits and which are often overlooked in the construction of cladistic matrixes. His conclusions are that a more comprehensive approach in morphological research should be stressed and that a strong effort is badly needed for the development of classical comparative anatomy versus the present trend towards ultra specialized studies; moreover, at the present stage of research, the available evidence is generally quite insufficient for the development of reliable matrixes of data, so that a more empirical and pragmatic approach is much safer.