L'Ariétitidé du Lias de Corse

Only one piece of liassic ammonite is known in Corsica (SE of St. Florent in the “unité of Tuda”). It is a Arietitidae, probably Paltechioceras or Vermiceras (top or bottom of Sinemurian). The Lias of Tuda, similar to that of “écailles de Corté”, belongs to parautochtonous external realm.     

L'adeninephosphoribosyltransferase des pousses de topinambour Helianthus tuberosus

An extract from Jerusalem artichoke shoots exhibited important adeninephosphoribosyltransferase activity. Only partial purification was possible because of the great instability of the enzyme. Phosphate ions and thiol reducing substances were necessary to stabilize it. The optimal temperature and pH were 40–45° and 5.5 to 6.5. The enzyme showed an absolute requirement for divalent cation: Mn²⁺ > Mg²⁺ = CO²⁺ = Zn²⁺ ? Ca²⁺. Kinetic studies gave K_m values of 6.4 × 10^?1 M for phosphoribosylpyrophosphate (PRPP) and 5.5 × 10^?6 M for adenine. AMP exercised a strong product inhibition, competitive towards PRPP (K_i = 10^?4 M). Inhibition by phosphate and pyrophosphate ions was also observed. The results suggested that the adeninephosphoribosyltransferase of Helianthus tuberosus has a key role in the purine salvage pathway.     

Further experiments on larval behaviour of the tubicolous polychaete Spirorbis inornatus L'Hardy & Quiévreux

Laboratory experiments indicate that there are many ecologically isolated populations of Spirorbisinornatus L'Hardy & Quiévreux, each tending to select the algal substratum which supported their parents. In some algae certain parts of the thallus are particularly favourable for settlement and, in some areas, this involves adaptation of the local population, e.g. to settle on fronds of Laminaria in sheltered localities. Other parts are unfavourable and these are generally the parts which are most illuminated in their natural orientation (e.g. the upper sides of Himanthalia buttons and the outer sides of Laminaria holdfast branches). These parts are active in producing antibiotics, which may thus have an antifouling role, deterring settlement of larvae whether or not those larvae come from populations adapted to settling upon other parts of the thallus.Most larvae from populations on the turf-alga Chondrus settle without any pelagic phase, whereas the majority from populations on Himanthalia and Laminaria holdfasts become pelagic. The proportions choosing holdfasts in laboratory experiments are high, however, suggesting that the need for skill in such choice, by these pelagic populations, more than balances any effect from outcrossing.     

L'action differentielle des hormones juveniles sur la metamorphose chez Locusta migratoria

The morphogenetic effect on metamorphosis of the three juvenile hormones is studied under experimental conditions that permit accurate conclusions in Locusta migratoria. Injections are made at the beginning on the last larval instar, which is the best time for action at the optimum level on the control of metamorphosis. Racemic hormones in stereochemical form comparable to that of natural compounds were used. Doses were chosen between 5 and 50 μg in order to give clear morphogenetic effects and give effects at a physiological level.A chronological study showed that juvenile hormones have the most important morphogenetic effect when injected in the first 40 hr of the last larval instar. Oiled solutions, stored at 4°C, lost only a small part of their morphogenetic activity after 9 months.Among the three hormones, JH-III presented the weaker morphogenetic effect, very significantly different from that of JH-I and JH-II. It has been possible to dissociate the effects of JH-I and JH-II on metamorphosis, JH-I giving a more potent action.     

L'ichthyofaune des marnes messiniennes des environs de Gabbro (Toscane,Italie): Signification paleoecologique

Five species of fossil Fishes, of which three are new (Aphanius italicus nov. sp., Palaeoatherina etrusca nov. sp. and Gobius ignotus nov. sp.) occur in the Messinian marls from Gabbro (Tuscany, Italy). This association allows to consider this locality as constituted in a continental basin with a variable salt content.     

L'alcool deshydrogénase de tomate (Lycopersicon esculentum): Étude cinétique et mécanisme d'action

In order to investigate the enzymatic mechanism of tomato alcohol dehydrogenase, kinetic studies were carried out at pH 5.8 and 9.4 for the forward and reverse reactions, respectively. Primary double reciprocal plots for several fixed concentrations of the associated substrate in all cases intersect, suggesting a sequential mechanism. Exploitation of secondary plots (slope-intercept values on the primary plots versus the reciprocals of the non-varied substrates) gives the following values: K_ms 500 μM for MeCHO, 30 μM for NADH, 2700 μM for EtOH, 12 μM for NAD⁺; K_is 40 μM for MeCHO, 3 μM for NADH, 10⁴ μM for EtOH and 45 μM for NAD⁺. The results obtained in product inhibition studies agree with an ordered bi-bi mechanism for both forward and reverse reactions. Application of Cleland's rules shows that the coenzyme was the first substrate to complex with the enzyme in both cases.     

Alcaloïdes des écorces de tronc et des écorces de racine de L'Hunteria elliotii

Nine known indole alkaloids were isolated from the stem and root barks of Hunteria elliotii: aspidofractinine, eburnamenine, eburnamine, isoeburnamine, eburnamonine, kopsinine, pleiocarpamine, quebrachamine and vincadifformine, along with o-ethyleburnamine.     

Material Studies of Lipid Vesicles in the Lα and Lα-Gel Coexistence Regimes

In this work, we utilize micropipette aspiration and fluorescence imaging to examine the material properties of lipid vesicles made from mixtures of palmitoyloleoylphosphocholine (POPC) and dipalmitoylphosphatidylcholine (DPPC). At elevated temperatures/low DPPC fractions, these lipids are in a miscible liquid crystalline (L_α) state, whereas at lower temperatures/higher DPPC fractions they phase-separate into L_α and gel phases. We show that the elastic modulus, K, and critical tension, τ_c, of L_α vesicles are independent of DPPC fraction. However, as the sample temperature is increased from 15°C to 45°C, we measure decreases in both K and τ_c of 20% and 50%, respectively. The elasticity change is likely driven by a change in interfacial tension. We describe the reduction in critical tension using a simple model of thermally activated membrane pores. Vesicles with two-phase coexistence exhibit material properties that differ from L_α vesicles including critical tensions that are 20–40% lower. Fluorescence imaging of phase coexistent POPC/DPPC vesicles shows that the DPPC-rich domains exist in an extended network structure that exhibits characteristics of a solid. This gel network explains many of the unusual material properties of two-phase membranes.     

L'Ichthyofaune des marnes messiniennes des environs de senigallia (Marche,Italie): Signification paleoecologique et paleogeographique

The revision of the fish fauna from the Messinian marls of Senigallia (Marche, Italy) leads to the reduction of the faunal list of the fossil Fishes found in this locality to only four species. One new genus is created: Cryptolebias new. gen.. This fish fauna characterizes an environment with a variable salt content: it may have been more or less temporarily connected with the sea, although it was also exposed to noticeable continental influences, as demonstrated by the occurrence of Amphibians and Reptiles (Ophidians).     

Publisher's note

During the late spring and early summer 1976, laboratory cultured cells of five marine algae were enclosed in dialysis sacks and grown in situ, in Ligurian coastal waters.Skeletonema costatum (Greville) Cleve did not grow at all. Hemiselmis virescens Droop stayed alive, but did not grow significantly. Platymonas suecica (Butcher) Manton &; Parke grew on cell reserves. Only Phaeodactylum tricornutum Bohlin and Thalassiosira pseudonana Hasle &; Heimdal took up nutrients from sea water when all reserves were exhausted. When division ended, all cells were capable of growing when sub-cultured, but physiologically were only slightly active. During immersion in oligotrophic waters, cell contents adapted quickly from nutrient-rich to nutrient-limited growth conditions. During adjustment to equilibrium with natural conditions, the three species became impoverished mainly in phosphorus (67–88% of initial values), ATP (54–92%), and chlorophyll a (59–89%); losses of nitrogen were lower (24–53%).To obtain algal material similar to that in the wild, the data suggest that the cells have to be kept in situ only until they divide five times, which usually requires no more than a week. Counting the cell density each day is probably the most convenient method of control, and each culture should be counted, because the difference of growth between aliquot dialysis cultures can be important (up to 28%).Data obtained for “wild-like” cells of Platymonas suecica, Phaeodactylum tricornutum, Thalassiosira pseudonana, and a wild contaminant population of Cylindrotheca closterium Rabenhorst with biochemical analysis used to run the Droop's model and with enrichment bioassays demonstrate that, during the period studied, phosphorus was the limiting factor for the algal growth. Bioassays also demonstrate that there were some specific variations; some algae were permanently limited by phosphorus, while for a few others nitrogen and phosphorus could be equally limiting.     

Kin selection and male androphilia in Samoan fa'afafine

The Kin Selection Hypothesis for male androphilia posits that genes for male androphilia can be maintained in the population if the fitness costs of not reproducing directly are offset by enhancing inclusive fitness. In theory, androphilic males can increase their inclusive fitness by directing altruistic behavior toward kin, which, in turn, allows kin to increase their reproductive success. Previous research conducted in Western countries has failed to find any support for this hypothesis. The current study tests this basic prediction of the Kin Selection Hypothesis for male androphilia by comparing the altruistic tendencies of androphilic and gynephilic males in the Polynesian nation of Independent Samoa. In Independent Samoa, androphilic males are known locally as fa'afafine. Altruistic tendencies were assessed using a Kin Selection Questionnaire. Comparisons of the altruistic tendencies of fa'afafine and gynephilic men revealed that these two groups did not differ in terms of their overall generosity and allocation of financial resources toward kin, nor did they differ in terms of general neediness or financial resources obtained from kin. Fa'afafine did, however, report greater avuncular tendencies than gynephilic men. Although the greater avuncular tendencies of fa'afafine support the basic prediction of the Kin Selection Hypothesis for male androphilia, further research is needed before one can conclude that these elevated tendencies represent a specially designed adaptation for promoting the fitness of kin. We discuss a number of sociocultural factors that might promote the expression of avuncular tendencies by androphilic males in Independent Samoa. Our results underscore the importance of testing functional hypotheses in evolutionarily appropriate environments.     

L'effet «Dumbbell dans le Concept d'évolution polyphasée

Dumbbell model rectification.     

Women's voice pitch lowers after pregnancy

Women's voice pitch (the perceptual correlate of fundamental frequency, F0) varies across the menstrual cycle and lowers after menopause, and may represent a putative signal of women's fertility and reproductive age. Yet, despite dramatic changes in women's sex hormone levels and bodies during and after pregnancy, previous between-subject and case studies have not found systematic changes in F0 due to pregnancy. Here, we tracked within-individual variation in 20 mothers' voices during their first pregnancy, as well as up to 5?years before conception and 5?years postpartum. Voice recordings from 20 age-matched nulliparous women were measured as a control. Linear Mixed Models indicated that F0 mean, range and variation changed significantly following pregnancy in mothers, controlling for age at time of recording, whereas we did not observe any F0 changes across corresponding timeframes in our sample of nulliparous controls. Mothers' voices became significantly lower-pitched and more monotonous during the first year postpartum compared to during pregnancy or before. These F0 parameters did not decrease within-individuals over a 5-year period prior to conception above and beyond the effects of ageing. Although voice pitch decreased following pregnancy, mothers' F0 parameters reverted after the first year postpartum, approaching pre-pregnancy levels. Our results demonstrate that pregnancy has a transient and perceptually salient masculinizing effect on women's voices.     

Alcaloides d'Araliopsis soyauxii. Isolement d'un nouvel alcaloide,l'Araliopsine

Six alkaloids have been isolated from root bark of Araliopsis soyauxii. Five are known, maculine, flindersiamine, skimmianine, (?) ribalinine, (+) isoplatydesmine and the sixth, araliopsine is new; its structure has been established as hydroxyisopropyldihydrofuro-2-quinolone. From the trunk bark four alkaloids have been isolated: flindersiamine, kokusaginine (?) ribalinine, (+) isoplatydesmine.     

Cinetique d'action de l'acide 2-chloro ethylphosphonique sur les polyribosomes du latex d'Hevea brasiliensis

Effects of 2-chloroethylphosphonic acid on the latex of Hevea brasiliensis were studied during 7 days after its application on the tapping panel of the tree. Ribosome polymerisation shows a dramatic rise within 12 hr after treatment. This shift is overcome at first without rRNA synthesis. Increase of latex production and latex pH exhibit similar features and start 24 hr after application of the, stimulant. After 4 days, rRNA concentration and the stability of the lutoïds (microvacuoles with lysosomal characteristics) change significantly.     

Phenylpolyenes d'Aspergillus niger: structure et proprietes de l'asperrubrol

When grown on a synthetic medium containing Zn²⁺ and Cd²⁺ in toxic concentrations and a high concentration of Mg²⁺, the mycelium of Aspergillus niger ATCC 9029 is pigmented yellow. Four pigments have been chromatographically separated. Two are still unknown; the others are asperenone and asperrubrol. Asperrubrol is the methyl ester of a dimethyl 13-phenyl-3-ol-2,4,6,8,10,12-tridecahexaenoic acid. One of the methyl groups is on C₂ and the other is probably at C₈. Asperrubrol has been obtained as the enol of the all trans molecule; ketoe nolisation can be obtained by action of heat or alkalis. When grown on the same medium, 13 of 17 strains of A. niger produced asperrubrol and asperenone.     

Action de l'hormone juvenile et de certains mimetiques sur l'epithelium intestinal chez Galleria mellonella

We have investigated the influence of juvenile hormone (JH) on the intestinal epithelium of G. mellonella, in vivo and in vitro. The larvae undergoing a supernumerary instar present a typical larval epithelium with columnar (CL) and globlet (CF) cells; the spinning period is characterized by a delay and a loss of synchronism in the process of differentiation of intermediates cells (Ci) typical of the pharate pupa. The larval-pupal intermediates show true mosaïcs in which Ci and CF are juxtaposed; however, the ratio of Ci in the epithelium progressively increases.The injection of JH at the beginning of spinning induces the appearance of CF just as Ci should normally grow. Hormone administration during the second half of the spinning period modifies the differentiation of epithelial cells: they become taller. We consider them to be cells engaged in pharate pupal differentiation, and which have then been partially oriented toward larval differentiation.These results show that the intestinal epithelium is a competent tissue, the sensibility of which to JH, is higher than that of the epidermis. The basal cell plasticity is very important and the action of JH on their differentiation may lead to CL or CF, to tall cells, and to Ci, depending on hormonal rate. In vitro, the experiments show that the action of JH is probably direct on the target tissue. The fact that JH can act very late as a modifier of the differentiation of the growing epithelial cells exclude the possibility that the hormone exercises its control through DNA replication.     

Collaborative and competitive motivations uniquely impact infants' racial categorization

Human history has been plagued by violent inter-group conflicts. Such conflicts are arguably grounded on group biases – particularly, a tendency to favor “ingroups” over “outgroups” – manifested in adults, children, and infants. A question these findings prompt is what motivates social categorization? Here it is shown that priming 14-month-old infants (N?=?144) with collaborative or competitive interactions affects their capacity to form racial categories, and that this effect varies according to the gender of the exemplars being categorized. Specifically, whereas racial categorization of women was facilitated by collaboration, racial categorization of men was facilitated by competition. The presence of these differential effects in infancy is consistent with the idea that social categorization is driven by fundamental functions of group relations.