Les vertébrés dévoniens de l'Iran central: II — Coelacanthiformes,Struniiformes, Osteolepiformes

The Frasnian vertebrate-bearing localities of the Kerman region (Central Iran) yielded remains referred here to the Coelacanthiformes, the Struniiformes and the Osteolepiformes. The Coelacanthiformes are represented by the genus Diplocercides, and the Struniiformes by Onychodus firouzi n. sp. and Strunius rolandi (Gross). Some isolated scales and dermal bone fragments are referred here to an undetermined Osteolepididae. This «crossopterygian fauna from Iran is closely similar to those known from the Upper Devonian of Northern Europe.     

Les vertebres devoniens de l'Iran central. III: Antiarches

The Upper Devonian of the Kerman region (Central Iran) has yielded but a few remains of antiarchs. Some ofthem may be referred to the almost world-wide distributed genus Asterolepis, whereas others are suggestive of the genera Byssacanthus and Stegolepis, previously recorded only from the Middle and Upper Devonian of Soviet Union.     

Purification and properties of methanol dehydrogenase from Methylophaga marina

Purification of methanol dehydrogenase from Methylophaga marina, in order to avoid the instability observed in crude extracts, was achieved initially by a rapid procedure using mainly an aqueous two-phase partition system composed of polyethylene glycol 1000 (50%, v/v) and potassium phosphate (50%, w/v). The purified enzyme gave a single band of protein after SDS-polyacrylamide gel electrophoresis. Antiserum raised against purified methanol dehydrogenase was used to detect possible protein contaminants in the enzyme preparation. The enzyme is an NAD-independent dehydrogenase containing pyrrolquinoline quinone (PQQ) as a prosthetic group. It is made of two apparently identical subunits giving a total MW of 145,000 for the native enzyme. The isoelectric point is 6.4. In addition to methanol and formaldehyde, multicarbon primary alcohols and aldehydes as well as secondary alcohols can be used as substrates. Except for ammonium chloride, which is a necessary activator in vitro, no effector was found which could modify the rate of enzyme activity under standard conditions of the assay. Although the main properties of this methanol dehydrogenase are similar to those already described in the literature, it does not belong in any of the five categories described by Anthony.     

Both sulfate-reducing bacteria and Enterobacteriaceae take part in marine biocorrosion of carbon steel

AIMS: In order to evaluate the part played in biocorrosion by microbial groups other than sulfate-reducing bacteria (SRB), we characterized the phylogenetic diversity of a corrosive marine biofilm attached to a harbour pile structure as well as to carbon steel surfaces (coupons) immersed in seawater for increasing time periods (1 and 8 months). We thus experimentally checked corroding abilities of defined species mixtures. METHODS AND RESULTS: Microbial community analysis was performed using both traditional cultivation techniques and polymerase chain reaction cloning-sequencing of 16S rRNA genes. Community structure of biofilms developing with time on immersed coupons tended to reach after 8 months, a steady state similar to the one observed on a harbour pile structure. Phylogenetic affiliations of isolates and cloned 16S rRNA genes (rrs) indicated that native biofilms (developing after 1-month immersion) were mainly colonized by gamma-proteobacteria. Among these, Vibrio species were detected in majority with molecular methods while cultivation techniques revealed dominance of Enterobacteriaceae such as Citrobacter, Klebsiella and Proteus species. Conversely, in mature biofilms (8-month immersion and pile structure), SRB, and to a lesser extent, spirochaetes were dominant. CONCLUSIONS: Corroding activity detection assays confirmed that Enterobacteriaceae (members of the gamma-proteobacteria) were involved in biocorrosion of metallic material in marine conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: In marine biofilms, metal corrosion may be initiated by Enterobacteriaceae.     

Fatty acid composition of rat liver mitochondrial phospholipids during ethanol inhalation

Male Sprague-Dawley rats were exposed to increasing concentrations (15-22 mg/l) of ethanol vapor over a 4-day period. Phospholipids were analyzed in liver mitochondria isolated from ethanol-treated and pair-weighted control animals. After a 2-day inhalation period, the proportion of monoenoic acids in total phospholipids increased, whereas that of arachidonic acid decreased. These changes were more striking in phosphatidylcholine (PC) than in phosphatidylethanolamine (PE). The decrease in 20:4 may be related to increased lipid peroxidation. After a 4-day inhalation period, quite different changes in phospholipid fatty acids were found. They consisted in a trend towards a more unsaturated system, the proportion of 20:4 being increased in PC and that of 22:6 in PE. This increase in polyunsaturated acids might be related to a direct ethanol effect on lipid structure and/or metabolism that would be linked to the high blood alcohol level present at this stage of ethanol intoxication.     

Motion from the past. A new method to infer vestibular capacities of extinct species

The vestibular system detects head movement in space and maintains visual and postural stability. The semicircular canal system is responsible for registering head rotation. How it responds to head rotation is determined by the rotational axis and the angular acceleration of the head, as well as the sensitivity and orientation of each semicircular canal. The morphological parameters of the semicircular canals are supposed to allow an optimal detection of head rotations induced by some behaviours, especially locomotor. We propose a new method of semicircular canal analysis, based on the computation of central streamlines of virtually reconstructed labyrinths. This method allows us to ascertain the functional structure of the semicircular canal system and to infer its capacity to detect particular head rotations, induced by particular behaviours. In addition, this method is well-suited for datasets provided by any kind of serial sectioning methods, from MRI to μCT scanning and even mechanical serial sectioning, of extant and extinct taxa.     

Age‐Related Differences in Daily Attention Patterns in Preschool,Kindergarten, First‐Grade,and Fifth‐Grade Pupils

The purpose of this study was to examine age‐related differences in the daily attention patterns of preschool, kindergarten, first‐grade, and fifth‐grade pupils by means of a cross‐sectional sample of 4–11‐year‐old French students. The importance of this study comes from the need to understand attention and apply the information it provides in educational settings. The first study conducted in a school setting with three age groups (4–5‐, 6–7‐, and 10–11‐year‐olds) demonstrated a rapid rhythmicity (60 minute period) for preschoolers (4–5 years old), with higher performance at the beginning of a teaching session. This pattern evolved until the fifth grade (10–11‐year‐olds), after which the temporal variation in attention was comparable to that of working adults, with fluctuations occurring on a half‐day basis. The children's scores on crossing‐out tests rose during the morning, declined in the early afternoon, and then rose again later during the afternoon. The second study enhanced our understanding of the change of the rhythm in attention of 4–7‐year‐old pupils. The rapid daily rhythmicity, linked to a session effect, seems to gradually disappear as children move from preschool 2 to kindergarten (4–5‐ to 5–6‐year‐olds) and then on to first grade (6–7‐year‐olds), where the daily attention patterns are closer to the standard pattern found by chronopsychology studies. The evolving patterns obtained from group means were confirmed by analysis of individual patterns. Exploratory statistical analysis of the data provided greater detail on the observed interindividual patterns, indicating that within each school grade, the attention patterns of some children are similar to the standard pattern while the attention patterns of others are more atypical. Deviations were mainly found in the 5–6‐year‐old age range (kindergarteners). The greatest ‘mixture’ of patterns was observed in the kindergartners (5–6‐year‐olds). Age plays a role not only in modifying daily changes but also in the distribution of interindividual differences in daily fluctuations, which occur most when children are of kindergarten age (5–6 years of age).     

Rab7A is required for efficient production of infectious HIV-1

Retroviruses take advantage of cellular trafficking machineries to assemble and release new infectious particles. Rab proteins regulate specific steps in intracellular membrane trafficking by recruiting tethering, docking and fusion factors, as well as the actin- and microtubule-based motor proteins that facilitate vesicle traffic. Using virological tests and RNA interference targeting Rab proteins, we demonstrate that the late endosome-associated Rab7A is required for HIV-1 propagation. Analysis of the late steps of the HIV infection cycle shows that Rab7A regulates Env processing, the incorporation of mature Env glycoproteins into viral particles and HIV-1 infectivity. We also show that siRNA-mediated Rab7A depletion induces a BST2/Tetherin phenotype on HIV-1 release. BST2/Tetherin is a restriction factor that impedes HIV-1 release by tethering mature virus particles to the plasma membrane. Our results suggest that Rab7A contributes to the mechanism by which Vpu counteracts the restriction factor BST2/Tetherin and rescues HIV-1 release. Altogether, our results highlight new roles for a major regulator of the late endocytic pathway, Rab7A, in the late stages of the HIV-1 replication cycle.