Échinodermes de l'Ordovicien supérieur (Ashgill) de Sardaigne et d'Algérie

Research on the influence of sea level variations on the benthic faunas have been carried out in the Upper Ordovician of Sardinia. Study of the depositional facies and sequence analysis of the upper part (Lower Ashgill) of the Portixeddu Formation led to the identification of the sedimentary environments. Cystoids and crinoids are associated to bryozoans and brachiopods in most levels. The numerical analysis of associations and megaguilds shows that crinoids and cystoids have a higher frequency in the proximal and median facies of the upper offshore. The columnal association characterized by Conspectocrinus celticus and the coronoid Mespilocystites tregarvanicus has been discovered in the upper part of the formation. This material and complementary samples from Upper Ordovician of Sardinia and Kabylia (Algeria) bring additional data on the systematic and show the wide distribution of this fauna outside of the Ibero-armorican domain. The distribution of this echinoderm association supports a palaeogeographical position of the Ibero-armorican domain and Sardinia within the north gondwanan margin during the Lower Palaeozoic.     

A phylogenetic analysis of basal Anseriformes, the fossil Presbyornis, and the interordinal relationships of waterfowl

A phylogenetic analysis of 123 morphological characters of basal waterfowl (Aves: Anseriformes) and other selected avian orders confirmed that the screamers (Anhimae: Anhitn-idae) are the sister-group of other waterfowl (Anseres), and that the magpie goose (Anseranatidae: Anseranas semipalmata) is the sister group of other modern waterfowl exclusive of screamers (Anatidae sensu stricto). The analysis also supports the traditional hypothesis of the gallinaceous birds (Galliformes) as the sister group of the Anseriformes. Presbyornis, a fossil from the early Eocene of Wyoming and averred by Olson & Feduccia as showing that the Anseriformes were derived from shorebirds (Charadriiformes), was found to represent the sister group of the Anatidae. Associated hypotheses by Olson & Feduccia concerning the implications of Presbyornis for the phylogenetic relationships of flamingos (Phoenicopteriformes), the position of the Anhimidae within the waterfowl, relationships among modern Anatidae, and a plausible evolutionary scenario for waterfowl also are rejected. Analyses revealed that cranial characters were critical to the establishment of the Galliformes as the sister group of the Anseriformes; exclusion of the Anhimidae, especially in combination with Anseranas, also undermined the support for this inference. Placement of Presbyornis as the sister group of the Anatidae casts doubt on the role suggested by Feduccia of ‘transitional shorebirds' in the origin of modern avian orders, and calls into question the concept of ‘fossil mosaics’. The phylogenetic hypothesis is used to reconstruct an evolutionary scenario for selected ecomorphological characters in the galliform-anseriform transition, to predict the most parsimonious states of these characters for Presbyornis, and to propose a phylogenetic classification of the higher-order taxa of waterfowl. This re-examination of Presbyornis also is used to exemplify the fundamental methodological shortcomings of the intuitive approach to the reconstruction of phylogenetic relationships.     

人工合成多样性突变文库研究进展*

突变文库的构建是定向进化研究过程中一个关键步骤,主要利用天然存在的系统或者人工合成的分子技术来产生多样性核酸分子文库,为制备和筛选具有一定特性的蛋白酶、多肽、人工抗体等提供庞大的遗传基因库,也可用于合成生物学中相关基因元件的研究与筛选,为目标生物制品的高效工业化生产提供动力。随着对突变文库构建技术研究的日益深入,各种文库构建策略相继被开发出来,并在生物能源、生物化工、生物医药、生物试剂和食品工业等方面得到了广泛的应用。然而,定向进化中的文库构建策略多有不同,各种突变文库构建技术的核心方法也在不断创新。主要介绍近年来实验室中人工合成多样性文库的前沿技术,并对文库构建技术在自动化和智能化方向的发展进行了展望。     

L’habitat en grotte au Néolithique : vers une estimation de l’intensité des occupations

The archaeological excavation of the cave of the Gardon has brought to light a dilated and nearly continuous stratigraphy for the Neolithic era. The analysis of lithic industry has showed the existence of variations between those neolithic layers, which are independents of the technological processes of tools productions. Four criteria allow us to characterize the occupation’s type of each layer. Compared to the excavations data and to sedimentological analysis, these results allow us to display the evolution of the intensity of occupations of the cave throughout the whole Neolithic.     

Scanning motion,ocellar morphology and orientation mechanisms in the phototaxis of the nematode Mermis nigrescens

Summary The putative ocellus of Mermis females consists of a hollow cylinder of dense hemoglobin pigmentation located in the anterior tip. The exact location of the photoreceptive nerve endings, however, is unknown. During phototaxis a continual bending or scanning motion of the head (anterior 2 mm) causes the orientation of the tip to swing about the direction of the source. By turning off (shuttering) the light source whenever the tip orientation was to one side of the source direction, the average orientation of the base of the head, and eventually the body orientation, was caused to be biased about 28° to the opposite side. Because the shuttering was synchronized with the scanning motion, the scanning motion must be involved in the maintenance of orientation to light. The direction of the bias rules out a two-signal comparison mechanism of orientation and demonstrates that a deviation of the tip from the source direction must decrease, rather than increase, the illumination of the photoreceptors. These findings, and the ocellar morphology, require that the photoreceptors be located inside the hollow tube of pigmentation where they can be shadowed by the pigment during deviations of the tip. Focusing by the curved anterior end should cause a similar modulation of the illumination at this location. The occasional episodes of transverse phototaxis can be explained by the leakiness of the pigment walls to transverse illumination. Analysis of the motion of the anterior in the presence and absence of shuttering indicates that the orientation of the base of the head, due to the motion of the neck, is controlled by the signals generated during one or more cycles of the scanning motion of the head. The orientation may be regulated by the phase relationship between the photoreceptor signal and putative proprioceptive signals that indicate the bending in the head.     

An NMR Study of the Spatial Structure and Intramolecular Dynamics of Modified Analogues of Steroid Hormones

Special features of the use of homo- and heteronuclear correlation methods of NMR in one and two dimensions for studying the spatial structure and intramolecular dynamics of modified analogues of steroid hormones (MASH) are considered. The application of these methods to the assignment of resonances in the high-field ¹H NMR region and to the determination of the most stereospecifically important parameters, such as the vicinal constants of spin–spin coupling (³ J _H–H) and nuclear Overhauser effects (NOE), are discussed using the example of NMR studies of some estrogens and androgens at 300 MHz and on the basis of literature data. The most efficient combination of the methods and the necessary modification of each of them may be chosen considering the spectral and relaxation parameters of MASH in liquid medium, including the anisotropy of the overall diffusive motion. The characteristics of MASH are the wide use of correlations through long-range couplings (COSY-45 and DQF-COSY), the application of the ^4,5 J _H–H constants for the determination of spatial structure, and the advantage of heteronuclear HSQC methods with and without ¹³C decoupling over the corresponding HMQC methods in both resolution and sensitivity. In the conformationally rigid MASH molecules, the anisotropy of the MASH diffusive motion in liquid adversely affects the determination of interproton distances by the calibrating processing method for the NOE difference and NOESY spectra: it results in both overestimated and underestimated distance values depending on the polar angle ratios of the reference and the determined distances. Under certain conditions, conformationally mobile MASH demonstrate the additional contribution of the scalar relaxation mechanism between the indirectly (scalarly) bound protons. This mechanism is responsible for the underestimated values of NOE and the corresponding errors in the distance determination.     

Evolutionary expansion of the Monogenea

The evolutionary expansion of the monogeneans has taken place in parallel with the diversification of the fish-like vertebrates. In this article the main trends in monogenean evolution are traced from a hypothetical skin-parasitic ancestor on early vertebrates. Special consideration is given to the following topics: early divergence between skin feeders and blood feeders; diversification and specialization of the haptor for attachment to skin; transfer from host to host, viviparity and the success of the gyrodactylids; predation on skin parasites and camouflage; colonization of the buccal and branchial cavities; diversification and specialization of the haptor for attachment to the gills; phoresy in gill parasites; the development of endoparasitism and the origin of the cestodes; the success of dactylogyroidean gill parasites; the uniqueness of the polyopisthocotyleans; ovoviviparity and the colonization of the tetrapods. Host specificity has been the guiding force of coevolution between monogeneans and their vertebrate hosts, but the establishment of monogeneans on unrelated hosts sharing the same environment (host-switching) may have been underestimated. Host-switching has provided significant opportunities for evolutionary change of direction and is probably responsible for the establishment of monogeneans on cephalopod molluscs, on the hippopotamus and possibly on chelonians. There are indications that host-switching may be more common in monogeneans that spread by direct transfer of adults/juveniles from host to host. A limitation on the further expansion of monogeneans is the need for water for the dispersal of the infective larva (oncomiracidium).     

Ultrastructural aspects of storage lipid mobilization in the tapetum of Lilium hybrida var. enchantment

Stages in the formation and degradation of pollenkitt in the anther of Lilium have been investigated using the electron microscope. This material, which appears to be a complex of lipid and carotenoids, is formed during the autolysis of the tapetal cells by the fusion of lipidic inclusions with globules derived from plastids. Autolysis of the tapetal cells is progressive for it commences with the disintegration of many cytoplasmic components, followed by the breakdown of storage lipids. The plasma membrane maintains its integrity during these events apparently, by proliferation, aiding in the transfer of the products of hydrolysis into the loculus. During the course of lipid breakdown, a striking vacuolar system is formed in the tapetal cytoplasm, presumably containing the products of this hydrolysis. The source of membranes for this system is clearly the lipid globules themselves. The generation of the membrane apparently involves the participation of electronopaque material, possibly enzymic, contained within the lipid globules.     

L’industrie du site néandertalien de la grotte de Vindija (Croatie) : une révision des matières premières lithiques

The new analysis of the Middle Paleolithic industry from the cave Vindija (Croatia), showed a necessity of revision of the previous obtained data especially considering the use and origin of the raw materials (Kurtanjek and Marci, 1990). The results presented in this study pointed out some new aspects of interpretation. First, the significance of quartz in the Middle Paleolithic was underestimated. At the same time it is obvious that the major change in the use of the raw material was at the beginning of the Upper Paleolithic and of the Epigravettian, especially in the use of chert. The second change is registered in the use of chert between Middle and Upper Paleolithic: the chalky nodules of chert are more frequent in the Upper Paleolithic then the river pebbles used in the production of Middle Paleolithic artefacts. Still, the origin of this new raw material is at the moment unknown.     

On the influence of fishes on the evolution of benthic crustaceans

Though the interweavement of trophic chains in marine ecosystems of the past cannot be reconstructed, as the abundance, nutrition, reproductive rates and other aspects of the biology of fossil species are not known, it is possible to correlate trends in the evolution of single groups of animals, in the presented case the Crustacea, with the influence of other evolving organisms. The evolution of carnivorous, buoyant, well swimming modern fishes probably induced profound changes in marine ecosystems and influenced the evolution of crustaceans. Indications for these interactions are a. the absence or rare occurrence of defenseless archaic crustaceans in habitats, which are populated by teleostean fishes and the survival of some of these forms in refuges like caves and subterranean waters, and b. the reduction of the pleon in the course of the mesozoic evolution of the Decapoda, which occurs parallel to the radiation of the Teleostei, namely in the period between the early Jurassic and the Tertiary. The shortening of the pleon is interreted as a consequence of the stepwise change from a hyperbenthic to a more benthic Iife-stJe and the abandonment of the caridoid escape reaction. Other adaptations are also construed as results from the selective pressure produced by predators. Extant crustaceans which are able to coexist with fishes, among the macrozoobenthos especially the Decapoda and Peracarida, have a variety of protective adaptations, which help to reduce predation.     

Seasonal distribution and abundance of tsetse flies (Glossina spp.) in the Faro and Deo Division of the Adamaoua Plateau in Cameroon

Ten years after the large-scale tsetse control campaigns in the important cattle rearing areas of the Faro and Deo Division of the Adamaoua Plateau in Cameroon, the seasonal distribution and abundance of tsetse flies (Glossina spp.) were determined. During a period of 12 consecutive months (January-December 2005), the tsetse population was monitored along four trap transects consisting of a total of 32 traps and two flyround transects traversing the study area, which comprised the tsetse-infested valley, a buffer zone and the supposedly tsetse-free plateau. Throughout the study period, a total of 2195 Glossina morsitans submorsitans and 23 Glossina tachinoides were captured in the traps and 1007 G. m. submorsitans (78.8% male flies) were captured along the flyround transects. All G. tachinoides and almost all G. m. submorsitans were captured in the valley. Five G. m. submorsitans were captured in traps located in the buffer zone, whereas no flies were captured in traps located on the plateau. The index of apparent abundance (IAA) of G. m. submorsitans was substantially higher in the areas close to game reserves. In the remaining part of the valley, where wildlife is scarce and cattle are present during transhumance (dry season), the IAA of tsetse was substantially lower. In this part of the valley, the abundance of tsetse seemed to be associated with the presence of cattle, with the highest IAA during transhumance when cattle are present and the lowest apparent abundance during the rainy season when cattle have moved to the plateau. It is concluded that the distribution of tsetse in a large part of the valley undergoes substantial seasonal changes depending on the presence or absence of cattle. The repercussions of those findings for the control of tsetse in the valley and the probability of reinvasion of the plateau are discussed.     

果实膨大期喷布磷酸二氢钾对三月红荔枝果实贮藏性的影响

在三月红荔枝(Litchi chinensis cv.Sanyuehong)果实膨大期对树冠喷施0.2%磷酸二氢钾(KP)水溶液,以探讨磷酸二氢钾对荔枝果实贮藏性的影响。结果表明:(1) KP处理的果实在贮藏期前17d,失重率及果肉可溶性固形物、酸、VitC、花色素苷等指标的变化趋势与对照基本相似;(2) KP处理的果肉可溶性蛋白质含量变化与对照有明显差异,而果皮的可溶性蛋白质含量在贮藏期前10d变化动态与对照一致,此后呈相反的变化趋势;(3)果皮POD活性显著高于果肉,KP处理和对照的果肉POD活性在贮藏第3d后、果皮POD活性在第17d前分别具有相似变化趋势;(4)果肉中CAT活性在贮藏第3~17d期间都显著或极显著高于果皮,KP处理和对照果肉、果皮CAT活性动态变化均为单峰曲线。     

Kinetic analysis of a general model of activation of aspartic proteinase zymogens

Starting from a simple general reaction mechanism of activation of aspartic proteinase zymogens involving an uni- and a bimolecular simultaneous route, the time course equation of the concentration of the zymogen and of the activated enzyme have been derived. From these equations, an analysis quantifying the relative contribution to the global process of the two routes has been carried out for the first time. This analysis suggests a way to predict the time course of the relative contribution as well as the effect of the initial zymogen and activating enzyme concentrations, on the relative weight. An experimental design and kinetic data analysis is suggested to estimate the kinetic parameters involved in the reaction mechanism proposed. Finally, we apply some of our results to experimental data obtained by other authors in experimental studies of the activation of some aspartic proteinase zymogens.     

Tumors in the remains of Ancient Egyptians

A survey of the tumors found in the remains of the Ancient Egyptians shows the occurrence of all the kinds of tumors which would be expected to be preserved in the osteological evidence. On the other hand, findings of tumors in the soft tissues of mummies are only exceptional. The frequency of tumors seems to be lower than in recent years, probably because of the shorter mean duration of life. The pathological lesions preserved in bony structure reveal not only osseous tumors, but also the presence of some tumors of soft tissues eroding the bone. To the survey of cases described in the literature, original findings of a calcified myoma uteri and of a probable epipharyngeal carcinoma are added. Because our knowledge on the history of tumors is not yet comprehensive, much more attention should be devoted to the search for them, starting from the moment of excavation of any cemetery.     

La gestion du quartz au Pléistocène moyen et supérieur. Trois exemples d’Europe Méridionale

Quartz is one of the main lithic resources employed along the Pleistocene for the manufacturing of tools. The abundance in all kind of environments leads to its frequent presence in archaeological sites. In spite of its suitability for knapping, the scarcity of specific researches on quartz industries has led to a view of this raw material as a second-rate resource, only used when flint was not available in the surroundings. Quite in opposition to this prejudice, the familiarity with the petrological and mechanical properties of the different varieties of quartz has led the Middle/Upper Pleistocene groups to a rational and differential exploitation of the available resources. There is a distinct selection of the varieties attending to the purposes of the exploitation and configuration. The patterns of exploitation of the cores are very standardized, based on longitudinal extractions and documenting the bipolar flaking technique. Moreover, when the raw material is of good quality, more sophisticated reduction methods such as the discoidal or the Levallois may be employed. On the other hand, for the purposes of configuration a clearly differential management of the raw material is attested: thus quartz is used for the small products (denticulates, side-scrapers, notches), while other stones (quartzite, porphyry and others) are devoted to the manufacturing of those tools demanding a more complex control of the elaboration (bifaces, cleavers, etc.). Either acting as the main lithic resource or as a complement to other raw materials, we can observe through the technological analysis of these lithic collections the great conceptual complexity depending on the needs to be fulfilled. Raw material quality allowing, the state-of-the-art technology of knapping can be applied to the quartz and, therefore, we should not understand its use as a consequence of environmental constrictions but rather as a result of the variability of the procurement strategies and management of lithic resources among the prehistoric communities.     

Homeosis, morphogenetic gradient and the determination of floral identity in the inflorescences ofPhilodendron solimoesense (Araceae)

A comparative developmental study of the inflorescence ofPhilodendron solimoesense was conducted using scanning electron microscopy. The spadix ofP. solimoesense is characterized by unisexual flowers. Staminate flowers are initiated on the upper portion of the spadix while pistillate flowers develop on the lower portion of the spadix. An intermediate zone located between the upper male and lower female portion of the inflorescence consists of sterile male flowers. Within this intermediate zone a row of flowers exhibit polarity with respect to the identity of sexual organs. Stamens are initiated on the flank of the floral meristem facing the upper male zone and carpels are initiated on the portion of the floral meristem facing the lower female zone. The resulting flowers therefore assume a bisexual identity. At the level of the inflorescence, all floral buds are initiated along a series of contact parastichies and the continuity of these parastichies is not disrupted at any level in the male, intermediate, and female zones on the spadix. Results from this study support the presence of a morphogenetic gradient acting at the level of the inflorescence and appears to be independent of the boundaries of floral primordia.     

The influence of explant orientation and contact with the medium on the pathway of shoot regeneration in vitro in epicotyl cuttings of Troyer citrange

The effect of orientation as regards to gravity, and that of contact with the medium of culture, on shoot regeneration at the cut edges of epicotyl explants of Troyer citrange (Citrus sinensis (L.) Osbeck×Poncirus trifoliata (L.) Raf.) have been separated. The shoot regeneration pathway was not affected by the orientation of the explants as regards to gravity, and was determined by explant polarity and the contact with the culture medium. At the apical edge of the explants, the contact with the medium shifted the pathway of shoot regeneration from a direct one to an indirect one, with formation of a callus. This callus formation was cytokinin-dependent, but the change in the pathway of organogenesis was not caused by the increase in cytokinin availability resulting from the contact with the medium. In contact with the media, regeneration at the basal edge of the explants occurred through an indirect pathway after callus formation. No regeneration occurred, at the basal edge, if the contact with the media was prevented. The orientation of the explants as regards to gravity affected shoot formation through the direct pathway of organogenesis. The number of buds differentiated, and that of growing shoots increased when the orientation of the explants departed from the vertical upright position.     

Madonna dell'Arma (San Remo, Italie) : expression locale de la végétation ligure au cours du Paléolithique moyen

Pollen analysis of Madonna dell’Arma cave inside part (Liguria, Italy) allowed us to reconstitute, at local scale, the Ligurian coastal vegetation between the end of the last interglacial period and the beginning of the pleniglacial. This transition period shows an important representation of arboreal cover and a persistence of thermophilous elements that allowed us to considerate the western Liguria as a periglacial refuge. During the end of the last interglacial, xerophytic, halophytic herbs and shrubs taken over from a Mediterranean pre-forest unit in the first slopes constituted the coastal zone. The nearness of Argentina torrent and the Armea influenced, in the coast, the existence of marshy zones colonized by hygrophilous trees. In the Ligurian lowlands spread out sclerophyllous and mesophilous forests according to altitude. The beginning of the pleniglacial is indicated in the sequence by increases of Pinus, Cupressaceae and Artemisia in the context of a decline in the thermophilous components. This picture of vegetation has become integrated into the multidisciplinary studies of the site and contributed to the elaboration of palaeoclimatic hypothesis similar as those revealed by the fauna.     

The influence of mass,volume and density on the frequency of recovery of fossil hominid hand and wrist bones

A study of the mass, volume and density of each of the wrist and hand bones of male and female human skeletons was undertaken. It was found that the mass and volume (i.e. size) of the bones are well correlated with the relative frequencies of preservation ofAustralopithecus and earlyHomo wrist and hand bones from fossil hominid sites in Africa. In general, the larger the bone, the greater its preservation frequency. In contrast to findings on bovid bones, the density of hand and wrist bones is not well correlated with the frequency of such bones recovered from these sites. These findings may be explained in terms of the agents of deposition of the bones, the physical nature of the deposit, and the methods of extraction of the fossils from the deposit.     

Biocontrol of Slugs in Protected Lettuce Using the Rhabditid Nematode Phasmarhabditis hermaphrodita

In two experiments, the rhabditid nematode Phasmarhabditis hermaphrodita, a parasite of slugs, was cultured in vitro and applied as a drench to soil at four dose rates (3 108, 1 109, 3 109 and 1 1010 ha-1) 1 or 4 days before planting lettuce seedlings in a polythene tunnel. The effects of the four nematode doses on slug damage during the first 3 weeks after planting and on the numbers of slugs found within and below lettuce plants at harvest were measured. Results were then compared with untreated plots and with plots where methiocarb pellets were applied at the recommended field rate. In the first experiment, methiocarb pellets significantly reduced the percentage of plants damaged by slugs, but the nematode did not. In the second experiment, methiocarb pellets and the second highest dose of nematodes significantly reduced the percentage of plants damaged by slugs. The different effect of the nematode in the two experiments may have resulted from differences in the timing of nematode application and/or differences in the pattern of slug damage between experiments. At the end of the first experiment, the highest two doses of nematodes and methiocarb pellets had significantly reduced the number of slugs found within lettuce plants at harvest and on the soil surface below the plants. At the end of the second experiment, analysis of variance showed no significant effects of any treatment on slug numbers or biomass, but regression analysis showed significant negative relationships between nematode dose and total slug numbers, numbers of Arion ater agg. and biomass of Deroceras reticulatum. In both experiments, increasing nematode dose significantly reduced the numbers of slugs found contaminating the harvested lettuce. At the end of the second experiment, the mean weight of individuals of A. ater agg. increased with rising nematode dose.