Typology of environmental conditions at the onset of winter phytoplankton blooms in a shallow macrotidal coastal ecosystem, Arcachon Bay (France)

Phytoplankton dynamics were assessed in the macrotidal ecosystemof Arcachon Bay through high-frequency surveys over a 5-yearperiod in order to characterize typology of environmental conditionsat the onset of the productive period. Temporal variations ofhydrological and biological parameters were examined in externaland internal waters of the lagoon, during the winter–springperiods from 1999 to 2003. An additional survey was performedduring winter–spring 2005 in order to study the verticalstructure of the water column. The occurrence of winter phytoplanktonblooms between January and March emerged as a recurrent event.The early onset of the productive period is influenced by thebiological functioning of adjacent Bay of Biscay oceanic waters.It is hypothesized that under a propitious hydrodynamic regime,phytoplankton inocula from the Bay of Biscay enter in the ArcachonBay where cells presumably find favourable conditions for theirfast development. The timing of the onset of those winter bloomsin Arcachon Bay seems to be mainly influenced by the presenceof anticyclonic weather conditions (associated with an increasein incident irradiance) during late winter (i.e. by February),while the water column does not show any particular stabilizationnor stratification liable to facilitate the onset of these blooms.Moreover, these winter blooms dominated by diatoms led to anearly nutrient depletion which could have inevitable consequenceson the structuration of the food web during spring and summer.     

Plasma Concentrations of Brain-derived Neurotrophic Factor in Patients Undergoing Minor Surgery: A Randomized Controlled Trial

We measured perioperative plasma concentrations of brain-derived neurotrophic factor (BDNF), a major mediator of synaptic plasticity in the central nervous system, in males, 30-65 years old, undergoing lumbar or cervical discotomy. Patients were randomly allocated to a general anesthetic with propofol induction and maintenance or with thiopental induction and isoflurane maintenance. BDNF plasma concentrations were measured before induction (baseline), 15 min after induction but before start of surgery, at skin closure, in the post-anesthetic care unit, and 24 h postoperatively. Data from 26 patients (13 in each group) were analyzed. At each time point, BDNF plasma concentrations showed large variability. At baseline, concentrations were 631 +/- 337 (mean +/- SD) pg ml(-1) in the propofol group and were 549 +/- 512 pg ml(-1) in the thiopental-isoflurane group (P = 0.31). At 15 min, concentrations significantly decreased in the propofol group (247 +/- 219 pg ml(-1), P = 0.0012 compared with baseline) but remained unchanged in the thiopental-isoflurane group (597 +/- 471 pg ml(-1), P = 0.798 compared with baseline). At skin closure and in the post-anesthetic care unit, concentrations were not different from baseline in both groups. At 24 h, concentrations significantly decreased below baseline in both groups (propofol: 232 +/- 129 pg ml(-1), P = 0.0015; thiopental-isoflurane: 253 +/- 250 pg ml(-1), P = 0.016). In the propofol group, there was a weak but statistically significant positive correlation (R2 = 0.38, P = 0.026) between the duration of surgery and BDNF plasma concentrations at skin closure. These data suggest that in males undergoing elective minor surgery, BDNF plasma concentrations show a specific pattern that is influenced by the anesthetic technique and, possibly, by the duration of surgery.     

A minimally invasive approach for correction of chin ptosis

Although ptosis of the tip of the chin is common and can be seen in persons of any age, it is frequently seen in older patients seeking facial rejuvenation. A variety of techniques have been described to correct ptosis of the chin. The authors describe a minimally invasive method that can be used correct chin ptosis. This technique uses a small intraoral incision to place a U-shaped Prolene suture that gathers the soft tissue of the chin and elevates it above the lower border of the mandibular symphysis. A retrospective review of 314 cases performed in conjunction with face lifts between January of 1994 and January of 2000 was performed to evaluate this technique. There were no significant complications, and long-term results have been very satisfactory and lasting.     

Activation and germination of Bacillus thuringiensis spores in Manduca sexta larval gut fluid

Incubation of Bacillus thuringiensis HD-1 spores in the larval gut fluid of Manduca sexta (tobacco hornworm) resulted in increased viable counts, conversion to phase-dark spores, and a loss of absorbance in spore suspensions, indicative of spore germination. Heat-activated and untreated spores incubated in water did not exhibit these changes. Only when spores were heat activated and incubated in germinants L-alanine and adenosine did changes in the spores approximate those observed in gut fluid. These data suggest that M. sexta larval gut fluid induces the activation and germination of B. thuringiensis spores.     

Treponema pallidum 3-phosphoglycerate mutase is a heat-labile enzyme that may limit the maximum growth temperature for the spirochete

In the causative agent of syphilis, Treponema pallidum, the gene encoding 3-phosphoglycerate mutase, gpm, is part of a six-gene operon (tro operon) that is regulated by the Mn-dependent repressor TroR. Since substrate-level phosphorylation via the Embden-Meyerhof pathway is the principal way to generate ATP in T. pallidum and Gpm is a key enzyme in this pathway, Mn could exert a regulatory effect on central metabolism in this bacterium. To study this, T. pallidum gpm was cloned, Gpm was purified from Escherichia coli, and antiserum against the recombinant protein was raised. Immunoblots indicated that Gpm was expressed in freshly extracted infective T. pallidum. Enzyme assays indicated that Gpm did not require Mn(2+) while 2,3-diphosphoglycerate (DPG) was required for maximum activity. Consistent with these observations, Mn did not copurify with Gpm. The purified Gpm was stable for more than 4 h at 25 degrees C, retained only 50% activity after incubation for 20 min at 34 degrees C or 10 min at 37 degrees C, and was completely inactive after 10 min at 42 degrees C. The temperature effect was attenuated when 1 mM DPG was added to the assay mixture. The recombinant Gpm from pSLB2 complemented E. coli strain PL225 (gpm) and restored growth on minimal glucose medium in a temperature-dependent manner. Increasing the temperature of cultures of E. coli PL225 harboring pSLB2 from 34 to 42 degrees C resulted in a 7- to 11-h period in which no growth occurred (compared to wild-type E. coli). These data suggest that biochemical properties of Gpm could be one contributing factor to the heat sensitivity of T. pallidum.     

Conus venoms: a source of toxins which interact with membrane- potential-dependent sodium channels

Marine snails of the genus Conus, as they are carnivorous predators, have a venom apparatus used to capture their prey. The toxins contained in the venoms of Conidae, called conotoxins, are of a particular high degree of diversity and represent powerful tools in the neuroscience field. Indeed, these toxins specifically bind with a high affinity to receptors and ionic channels. Therefore, they provide original pharmacological tools which receive increasing investigation both to identify and study some functions of the nervous systems and to characterize new types and closely related subtypes of receptors or ionic channels. The voltage-gated sodium channel, because of its fundamental role in cell membrane excitability, is the specific target of a large number of animal and vegetal toxins. Actually, at least seven toxin receptor sites have been identified on this channel-protein. These toxins, and in particular conotoxins, are used to precise the role of different types and/or closely related subtypes of sodium channels in the peripheral and central nervous systems. The focus of the present review is to summarize our current knowledge of the consequences of physiological interactions between different conotoxin families and sodium channels.     

Response surface methodology, an approach to predict the effects of a lactoperoxidase system, Nisin, alone or in combination, on Listeria monocytogenes in skim milk

Experimental designs using Response Surface Methodology (RSM) were used to determine effects and interactions of Nisin (0-200 i.u. ml-1), pH values (5.4-6.6), incubation time (0-36 h or 0-144 h) and the lactoperoxidase-thiocyanate-hydrogen peroxide system (LPS) on Listeria monocytogenes CIP 82110 in skim milk, at 25 degrees C. The LPS varied from level 0-2; LPS at level 1 consisted of lactoperoxidase (35 mg l-1), thiocyanate (25 mg l-1) and H2O2, which was supplied exogenously by glucose-oxidase (1 mg l-1) and glucose (0.2 g l-1); LPS activity was dependent on LPS level and incubation time. In the presence of LPS at level 1, a bacteriostatic phase was followed by growth, whereas at a higher level, a bactericidic phase was observed. Nisin response was time- and pH-dependent. Nisin was bactericidic at acidic pH values and for a short incubation time (12 h) only; then, a re-growth phase was observed. Nisin and LPS in combination gave an original response which lacked the transitory bactericidal effect of Nisin and had a continuously bactericidal affect, leading to 10 cfu ml-1 of L. monocytogenes at 144 h; the response was greatly affected by incubation time. Predicted values were in good agreement with experimental values. Response Surface Methodology is a useful experimental approach for rapid testing of the effects of inhibitors.