Interactions of the HIV-1 fusion peptide with large unilamellar vesicles and monolayers. A cryo-TEM and spectroscopic study

We have examined the interaction of the human immunodeficiency virustype 1 fusion peptide (23 amino acid residues) and of a Trp-containing analog with vesicles composed of dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine and cholesterol (molar ratio, 1:1:1). Both the native and the Trp-substituted peptides bound the vesicles to the same extent and induced intervesicular lipid mixing with comparable efficiency. Infrared reflection-absorption spectroscopy data are compatible with the adoption by the peptide of a main beta-sheet structure in a cospread lipid/peptide monolayer. Cryo-transmission electron microscopy observations of peptide-treated vesicles reveal the existence of a peculiar morphology consisting of membrane tubular elongations protruding from single vesicles. Tryptophan fluorescence quenching by brominated phospholipids and by water-soluble acrylamide further indicated that the peptide penetrated into the acyl chain region closer to the interface rather than into the bilayer core. We conclude that the differential partition and shallow penetration of the fusion peptide into the outer monolayer of a surface-constrained bilayer may account for the detected morphological effects. Such single monolayer-restricted interaction and its structural consequences are compatible with specific predictions of current theories on viral fusion.     

Mosasaurus beaugei Arambourg, 1952 (Squamata, Mosasauridae) from the Late Cretaceous phosphates of Morocco

Mosasaurus beaugei Arambourg, 1952 was based on isolated teeth from the Maastrichtian phosphatic deposits of Morocco. The recent discovery of new material, including skull and mandibular remains, improves our knowledge of this species. M. beaugei shares the following synapomorphies with the genus Mosasaurus: large teeth bearing two prominent carinae and with asymmetrical labial and lingual surfaces, the labial one being flattened and strongly facetted and the lingual one being convex; premaxillae with a small pointed rostrum and dentary without rostrum; palatal elements closely united; coronoid with very large ventromedial process overlying the prearticular. M. beaugei is characterised by the following autapomorphies: 12-13 maxillary teeth; marginal teeth bearing 3-5 prisms on the labial surface and 8-9 on the lingual one; palatine with posterior border concave and perpendicular to the long axis of the skull; splenial visible laterally on half of the dentary ventral surface; coronoid with anterior wing well developed and bearing two notches. M. beaugei is only known to date in the Maastrichtian phosphates of Morocco.     

Classification of Leptospira isolated in Peru]

Antigenic properties of 23 leptospira cultures isolated in Peru were studied by immunological absorption. Two new individual leptospira serovars were classified as huanuco with a reference strain M-4, representing a new Huanuco serological group, and san-martini with a reference strain CT-63 belonging to the Hebdomadis serological group. Besides for the first time in the American part of the world serovar budapest belonging to Icterohaemorrhagiae serological group was recorded; also the first finding of serovar pyrogenes of the pyrogenes serological group was certified.     

Is weight an important parameter when measuring copepod growth?

We studied in situ weight increment of Calanus helgolandicus developing under field conditions. Weight increment between successive stages was rather similar for early nauplii (NII-NV ∼2.00 μgC μgC⁻¹) and for early copepodites (NVI-CIII mean: ∼2.40 μgC μgC⁻¹) but lower for late copepodites (CIV ∼0.80 and CV ∼0.20 μgC μgC⁻¹). Weight increment of CIV and particularly CV was found to be closely linked to the method used to estimate the weight: either (i) directly measured weights, or (ii) weights estimated from a length-weight regression. The weight of CV, which has a relatively long stage duration, shows wide variations within the stage while length variations within stage are very low. For example, on the 17th of August, some CV had a carbon weight three times higher than other ones. The main cause of variation is the age of the individuals within the stage.We recommend direct weight measurement rather than the use of length-weight regression to estimate weight increment. However, and especially for stages with large variations in weight, whether the individuals are at the mid-point of their stage should be checked.     

Secondary production of Calanus helgolandicus in the Western English Channel

The objective of this study was to investigate the production of Calanus helgolandicus off Plymouth, Western English Channel, from April to August 1998 comparing a range of different methods. The abundance of all developmental stages from NI to adult was determined. Body carbon and nitrogen and length were measured on individual NVI to adults. Female egg production was also monitored. All developmental stages were generally represented but four main periods of recruitment were determined. Two periods of low egg production were observed on the 13th and on the 27th of July: (i) the first was due to the arrival of newly moulted or not yet fertilised females in the population and (ii) the second low period was possibly due to the senescence of the females. Finally, the total production of C. helgolandicus was estimated using four different methods: the weight increment, the egg production, Huntley and Lopez and Hirst and Lampitt methods. Depending on the methods used, the production accumulated over the period from May 14 to August 10 ranged between 12 and 45 mg C m⁻³.     

Spring zooplankton distribution in the Bay of Biscay from 1998 to 2006 in relation with anchovy recruitment

The objective of this study was to investigate whether successiverecruitment failures in the anchovy fishery in the Bay of Biscaywere due to changes in the zooplankton biomass or composition.Image analysis and automatic recognition were used to analysezooplankton samples collected during diel egg production methodspring surveys from 1998 to 2006. We were not able to detectany trend in zooplankton biomass during this period. The zooplanktonspatial distribution showed permanent features with large organismsbeing more abundant over the shelf break and outer areas. Finally,we found a negative correlation between anchovy recruitmentand zooplankton biomass which suggests that the 2002–2006failures in anchovy recruitment in the Bay of Biscay are notdue to a decrease in mesozooplankton biomass.     

A method for capturing and GPS tracking breeding White-backed Woodpeckers Dendrocopos leucotos

ABSTRACT

Capsule: The use of mist nets placed at more than 9?m high and small GPS tags fitted with a pelvic harness, and equipped to download remotely, allows the capture and tracking of breeding White-backed Woodpeckers Dendrocopos leucotos.

Aims: To describe and test a method for capturing, ringing and GPS-marking medium-sized woodpeckers.

Methods: Birds were captured using an overlapping mist net system located between two poles with a minimum height of 9.25?m and a maximum of 12.95?m, previously designed for catching bats. Once captured, the birds were ringed and fitted them with a remote download GPS tag, weighing 3.4?g.

Results: Twenty individuals (17 adults and 3 juveniles) from 14 territories were captured during the 28 sampling days. All marked breeders continued with chick provisioning and in 12 of the territories were successful in fledging young. We found no significant difference in the number of fledglings between nests where the breeders were captured and tagged with devices (1.71?±?0.19 se) and nests where the breeders were not captured (1.71?±?0.29 se). The GPS tags allowed us to obtain a mean of 102.6 (±15.91 se) locations for each bird during a tracking period averaging 57.8 (±10.4 se) days. Despite the steep slope and the high forest canopy in the hábitat, 77.09% of GPS locations were accurate to within 20?m.

Conclusion: Our results showed that this method allows us to obtain important information about the habitat use of this species during the breeding period without any apparent effect on reproductive success.