L'appareil de Golgi des Ciliés. Ultrastructure, particulièrement chez Paramecium

Electronmicroscopic study of Coleps, Colpidium, Stylonychia, and especially of Paramecium confirmed the presence of the Golgi complex in these fresh-water ciliates. The complex consisted of numerous dictyosomes scattered throughout the cytoplasm. Each dictyosome included a few flat, partly reticulated saccules lying parallel to a cistern of rough endoplasmic reticulum which was free of ribosomes on the side exposed to the dictyosome. A unique layer of vesicles, characterized by constant size and a thick wall, separated the endoplasmic reticulum from the dictyosomes. The vesicles could be regarded as transition vesicles. Coated vesicles were seen in continuity with some of the flattened saccules. The possible role of the Golgi complex in the physiology of ciliates is discussed.     

Multimodal pyrethroid resistance in malaria vectors, Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus s.s. in western Kenya

Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus s.s. are the most important species for malaria transmission. Pyrethroid resistance of these vector mosquitoes is one of the main obstacles against effective vector control. The objective of the present study was to monitor the pyrethroid susceptibility in the 3 major malaria vectors in a highly malaria endemic area in western Kenya and to elucidate the mechanisms of pyrethroid resistance in these species. Gembe East and West, Mbita Division, and 4 main western islands in the Suba district of the Nyanza province in western Kenya were used as the study area. Larval and adult collection and bioassay were conducted, as well as the detection of point mutation in the voltage-gated sodium channel (1014L) by using direct DNA sequencing. A high level of pyrethroid resistance caused by the high frequency of point mutations (L1014S) was detected in An. gambiae s.s. In contrast, P450-related pyrethroid resistance seemed to be widespread in both An. arabiensis and An. funestus s.s. Not a single L1014S mutation was detected in these 2 species. A lack of cross-resistance between DDT and permethrin was also found in An. arabiensis and An. funestus s.s., while An. gambiae s.s. was resistant to both insecticides. It is noteworthy that the above species in the same area are found to be resistant to pyrethroids by their unique resistance mechanisms. Furthermore, it is interesting that 2 different resistance mechanisms have developed in the 2 sibling species in the same area individually. The cross resistance between permethrin and DDT in An. gambiae s.s. may be attributed to the high frequency of kdr mutation, which might be selected by the frequent exposure to ITNs. Similarly, the metabolic pyrethroid resistance in An. arabiensis and An. funestus s.s. is thought to develop without strong selection by DDT.     

Trans-continental visible morph-frequency variation at homologous loci in two species of spider, Enoplognatha ovata s.s. & E. latimana

The spiders Enoplognatha ovata s.s. and E. latimana are sibling species which share a number of visible genetic polymorphisms. Data on colour and black-spotting morph frequencies in these species have been collected from 67 sites in western Europe. Sixty nine percent of the collections contained both species. In all adequately-sized samples, both species were polymorphic for colour and, in general, exhibited the same rank order of morphs lineata and redimita. (The top dominant morph, ovata, has not been found in E. latimana). Colour-morph frequencies are not correlated between species in sympatric populations from mainland Europe and from a previously studied area in Pembrokeshire, South Wales. Although associations with certain climatic variables are evident in E. ovata they are not consistent between transects, making their biological significance unclear. For black spotting, E. ovata s.s. is nearly fixed for spotting throughout mainland Europe but is highly variable in the Pembrokeshire populations. E. latimana is polymorphic in both areas. In Europe, spotting frequencies in E. latimana show significant associations with climatic factors but, again, their biological significance is not obvious. In E. ovata s.s. the variance in both colour and spotting frequencies among populations in Pembrokeshire is significantly greater than that in the whole of mainland Europe. The implications of these and previous results are considered in the context of the persistence of visible polymorphisms across species and the forces which determine morph frequencies in local populations.     

« Statut de Berger » des communautés atlasiques, néolithisées du Maghreb oriental, dès 7000 BP

Neolithization through karstic rocky territories from Eastern Maghreb is supported by a special form of pastoralism. Between 7000-5000 BP, a prominent sheep and goat animal husbandry represents a shepherd’ permanent objective, while domestic cattle seems to play a saving role. Aurès reaches allowed us to study a global shepherd living, initiated by small groups, labelled as Neolithic of Capsian Tradition, stricto sensu (NCT). A new approach focuses here on non local archaeological finds from the Capéletti cave, a residential key-site located on the slopes of the Khanguet Si Mohamed Tahar amphitheatre (1540m), gives the lead to explore a winter lowland transhumance behaviour, which was a yearly extension of a summer upland behaviour. Through synchronized data, selected among exotic cultural documents, such as polished stone axes and adzes; marine and ivory-ornaments; and lowland botanic remains from marshes, such as elements of a steppic and salted vegetation, trapped inside sheep fleece, new evidences emerged which were linked, then, with new data based on flocks evaluation as alive animals. This study gives precision on:

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the shepherd’s long term objective;

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the initial and natural animal husbandry which moved, through an empirical management, on an increasing and controlled sheep, goat and cattle breeding;

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the non local cultural goods broad-spectrum, coveted by the shepherds;

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the flock meat/animal goods, coveted by peddling nomadic people;

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the exchange act and its conventions;

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how and when vanished epipaleolithic traditions of this NCT facies, through shepherds’ deliberate and progressive exchanges;

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and how and when, outside farming process, might have appeared, on lowlands and hilly areas, a typical open countryside landscape, strictly linked with this ongoing pastoralism.

This first local Status of the Shepherd which was the main objective of this neolithization may have settled and spread out through Maghreb territories, an Atlasic Pastoral Society.     

Description de Quelques Espèces de Ciliés Hyménostomes des Genres Sathrophilus Corliss, 1960, Cyclidium O. F. Müller, 1786, Histiobalantium Stokes, 1886

RESUME. Les structures buccales de Sathrophilus vernalis Dragesco & Grolière, 1969 sont détaillées. La morphogenèse buccale de l'opisthe, semi-autonome, avec participation du scuticus et d'une cinétie postorale droite, s'accompagne d'une re-constitution de l'appareil buccal du proter. La morphologie buccale de Cyclidium sphagnetorum Šràmek-Hušek, 1949 est comparée à celles de Cyclidium citrullus Cohn, 1865 et Cyclidium glaucoma O. F. Müller, 1786. La stomatogenèse Histiobalantium majus Kahl, 1933 débute par une prolifération du scuticus vers la gauche.
SYNOPSIS. Buccal structures of Sathrophilus vernalis Dragesco & Grolière, 1969 are described. The semiautonomous buccal morphogenesis of the opisthe, involving the participation of the scuticus and the right postoral kinety, is accompanied by the reconstitution of the buccal apparatus of the proter. The buccal structure of Cyclidium sphagnetorum Šràmek-Hušek, 1949 is compared to those of Cyclidium citrullus Cohn, 1865 and Cyclidium glaucoma O. F. Müller, 1786. Stomatogenesis of Histiobalantidium majus Kahl, 1933 starts with a proliferation of the scuticus towards the left.     

Floral nectaries in Sapindaceae <Emphasis Type="Italic">s.s.</Emphasis>: morphological and structural diversity,and their systematic implications

We investigated the morphology and structure of the floral nectary in 11 Neotropical genera belonging to the subfamilies Dodonaeoideae and Paullinioideae (Sapindaceae) from southern South America representing three tribes (Dodonaeaeae, Paullinieae, and Melicocceae), in relation to other floral traits in species with contrasting morphological flower characteristics. Nectary organization was analyzed under light, stereoscopic, and scanning electron microscopes; Diplokeleba floribunda N.E. Br. was also observed using transmission electron microscopy. Our comparative data may contribute to the understanding of floral nectary evolution and systematic value in this family. The nectaries were studied in both staminate and pistillate flowers. All the floral nectaries are typical of Sapindaceae: extrastaminal, receptacular, structured, and persistent. The anatomical analysis revealed a differentiated secretory parenchyma and an inner non-secretory parenchyma; the nectary is supplied by phloem traces and, less frequently, by phloem and xylem traces. Nectar is secreted through nectarostomata of anomocytic type. The anatomical analysis showed the absence of nectary in the three morphs of Dodonaea viscosa flowers. Nectary ultrastructure is described in D. floribunda. In this species, the change in nectary color is related to progressive accumulation of anthocyanins during the functional phase. We found relatively small variation in the nectary structural characteristics compared with large variation in nectary morphology. The latter aspect agreed with the main infrafamilial groupings revealed by recent phylogenetic studies, so it is of current valuable systematic importance for Sapindaceae. In representatives of Paullinieae, the reduction of the floral nectary to 4–2 posterior lobes should be interpreted as a derived character state.     

Recycling,reproduction, and life's origins

Kinetic considerations make it most improbable that any reproducing system could arise spontaneously in a prebiotic soup containing a large variety of organic molecules, as commonly postulated. This batch process can be contrasted with a completely recycling network of reactions maintained by an influx of energy. So long as the network includes at least two bimolecular reactions it is likely to support pathways for chemical reproduction. However, such reproducing systems will be simple in both kinetic and structural terms. Subsequent evolution will lead to much more complex reproducing structures although the kinetic complexities, measuring the varieties of reactions between these structures and their media, will remain relatively simple.     

Microstachys crassifolia sp. nov. (Euphorbiaceae) from Chapada dos Veadeiros,Goiás,Brazil

Microstachys crassifolia, a new species from Chapada dos Veadeiros region in the State of Goias, central Brazil, is here described and illustrated. Its habit and general morphology resembles that of M. nana Silva & Esser, an endemic species from the State of Paraná, southern Brazil. Both species are hemicryptophytes from grasslands, with a well‐developed underground system, glabrous leaves and reddish inflorescences and fruits, but M. crassifolia has fleshy leaves without glands while M. nana has membranaceous leaves with pateliform, submarginal glands.     

Comparative wood anatomy of Andromedeae s.s., Gaultherieae, Lyonieae and Oxydendreae (Vaccinioideae, Ericaceae s.l.)

The wood anatomical structure of 11 out of 13 genera from four tribes of the Vaccinioideae, namely Andromedeae s.s. , Gaultherieae, Lyonieae and Oxydendreae (Ericaceae s.l. ), is described using light and scanning electron microscopy. Several features of the secondary xylem support the tribal classification based on molecular data: arrangement of vessel-ray pitting, height of multiseriate rays and the shape of the body ray cells. Oxydendreae are clearly defined from the other representatives by various wood anatomical features. Gaultherieae can be distinguished from Lyonieae by differences in vessel perforation plates, vessel-ray pitting, height and structure of multiseriate rays, and occurrence of prismatic crystals, but the wood of Andromedeae s.s. is similar to Gaultherieae. Moreover, Andromedeae s.s. , Oxydendreae and Vaccinieae are characterized by their pith structure, whereas considerable variation in the pith cells is found in Lyonieae and Gaultherieae.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 161–179.