Search results for "Systematics"
showing 10 items of 6702 documents
Meiofauna and benthic microbial biomass in a semi-enclosed mediterranean marine system (Stagnone di Marsala, Italy)
2004
Microbial and meiofaunal dynamics and their relationships with the biochemical composition of the sedimentary organic matter were investigated in a semi-enclosed marine system (Marsala lagoon, Western Sicily, Mediterranean Sea). Sediment samples were collected on a monthly basis from March 1996 to February 1997 in four stations located along a N–S transect characterized by different hydrodynamic regimes. Total sedimentary organic matter concentration ranged from 5.681.11 to 156.2812.63 mg g1, while the biopolymeric fraction of organic carbon (BPC, measured as sum of the lipids, carbohydrates and proteins) accounted for only a small fraction (24%) of total organic matter. Total meiofaunal de…
Holothuria tubulosa Gmelin 1791 (Holothuroidea, Echinodermata) enhances organic matter recycling in Posidonia oceanica meadows
2014
Abstract The role of Holothuria tubulosa in organic matter recycling of Posidonia oceanica detritus was estimated in a laboratory feeding experiment. The individual mean ingestion rate of seagrass detritus by holothurians was evaluated and carbon and nitrogen stable isotopes, carbon and nitrogen content and C:N ratio analyzed in H. tubulosa , P. oceanica detritus and surface sediment. Results showed that H. tubulosa is capable of ingesting from 30% to 100% of the detritus produced by P. oceanica meadows, depending on the holothurian density. Stable isotope analysis provided evidence for the assimilation of seagrass detritus by H. tubulosa as their signatures were compatible with 1 trophic l…
Sur la présence de matières organiques mésocénozoïques dans des humus actuels (bassin de Chaillexon, Doubs, France)
1998
Abstract The optical analysis in the Chaillexon watershed (Doubs, France), of the present soils' humus layers' organic matter points out the contribution of Meso-Cenozoic organic matter in addition to the one produced by vegetal cover. Their relative occurrence varies in each layer: in the reverse of that of vegetal organic matter, the relative amount of Meso-Cenozoic organic matter increases according to the depth. That result shows that the total organic matter amounts in soils (and its evaluation) do not only depend on the net primary production and that geological formations have to be taken into account. Moreover, it suggests that present and past detrital supplies are concerned with ‘…
Protein and amino acid composition of the tergal gland secretions ofBlatta orientalis andEurycotis floridana (Dictyoptera: Blattidae)
1994
Summary Nymphs and adult females ofBlatta orientalis and nymphs ofEurycotis floridana produce a proteinaceous sticky secretion which accumulates on the last abdominal tergites. The proteic patterns do not differ between individuals of the same species. HPLC analyses show that all the common amino acids are found in both species, aspartic and glutamic acids representing 24 to 37% of the total amount of amino acids. InB. orientalis, glutamic acid is the more abundant amino acid whereas inE. floridana it is the aspartic acid. The secretion appears and accumulates rapidly on isolated insects. Behavioural assays revealed that these secretions have a defensive role.
A chemotaxonomic survey of Sonchus subgenus Sonchus
1993
Abstract Five species of Sonchus subgenus Sonchus were surveyed for their phenolic constituents. Seven flavonoids were identified: luteolin, luteolin-7-glucoside, apigenin, apigenin-3-glucoside, quercetin, quercetin-3-glucoside and quercetin-3-galactoside; three were phenolic acids; caffeic, chlorogenic and isochlorogenic; and two were coumarins: aesculetin and cichoriin. Their systematic significance for this genus is discussed.
Lactobacillus vini sp. nov., a wine lactic acid bacterium homofermentative for pentoses.
2006
Six strains with more than 99·5 % 16S rRNA gene sequence similarity, identical internal spacer region profiles and restriction analysis of the amplified 16S rRNA gene patterns were isolated from fermenting grape musts during independent studies carried out in France and Spain many years apart. Strains are Gram-positive, motile, facultatively anaerobic rods that do not exhibit catalase activity and have the ability to utilize pentose sugars (ribose and/or l-arabinose), although they are homofermentative bacteria. Strains ferment pentoses exclusively yielding lactic acid as the end product. A broad set of molecular techniques has been applied to characterize these strains and the results show…
Immediate early response of the marine sponge Suberites domuncula to heat stress: Reduction of trehalose and glutathione concentrations and glutathio…
1997
The marine sponge Suberites domuncula was used to identify early markers for thermal stress. Cubes from sponges have been kept for 30 min at 31°C (10 °C higher than the ambient temperature). After this treatment the sponge cubes were kept again at 21°C. To demonstrate that the animals reacted to the elevated temperature, the expression of heat shock protein (HSP) was determined. Using an antibody raised against HSP70, it was found by Western blotting that the animals specifically express a 45 kDa polypeptide after heat treatment. It was shown that even after 10 min of heat treatment the steady-state concentration of trehalose drops by 40% from a base level of 13 nmol/mg protein. The activit…
Locust flight metabolism studied in vivo by 31P NMR spectroscopy
1991
Flight metabolism of locusts has been extensively studied, but biochemical and physiological methods have led to conflicting results. For this reason the non-invasive and non-destructive method of 31P NMR spectroscopy was used to study migratory locusts, Locusta migratoria, at rest and during flight. 1. In the flight muscle of resting locusts the ratio of phosphoarginine to ATP was the same whether determined by NMR (1.76) or biochemically, but the NMR-visible content of inorganic phosphate (Pi) was only 40% of ATP, i.e., much lower than total Pi as determined biochemically. This suggests that most of the Pi in flight muscle is not free, and hence not available as substrate or effector for …
Orbitally induced limestone/marlstone rhythms in the Albian—Cenomanian Cismon section (Venetian region, northern Italy): Sedimentology, calcareous an…
1996
Abstract A multidisciplinary study of the upper Albian—Cenomanian portion of the Cismon section (Venetian region, northern Italy) was undertaken in order to characterize the cyclic alternations of carbonate-rich and carbonate-poor layers and to investigate their possible origin and cyclic patterns. Limestone semicouplets are characterized by abundant radiolarians and micarbs (micron-sized calcitic fragments), common planktonic foraminifera, strong bioturbation, good oxygenation as expressed by the Mn* and V/(V+Ni) parameters, high Si/Al ratio, low K/Al, in the absence of pyrite and organic matter. The marlstone semicouplets are, on the contrary, frequently laminated, rich in pyrite and orga…
Novel host-specific iron acquisition system in the zoonotic pathogenVibrio vulnificus
2015
Summary Vibrio vulnificus is a marine bacterium associated with human and fish (mainly farmed eels) diseases globally known as vibriosis. The ability to infect and overcome eel innate immunity relies on a virulence plasmid (pVvbt2) specific for biotype 2 (Bt2) strains. In the present study, we demonstrated that pVvbt2 encodes a host-specific iron acquisition system that depends on an outer membrane receptor for eel transferrin called Vep20. The inactivation of vep20 did not affect either bacterial growth in human plasma or virulence for mice, while bacterial growth in eel blood/plasma was abolished and virulence for eels was significantly impaired. Furthermore, vep20 is an iron-regulated ge…