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Comptes Rendus Biologies

Alastair A Macdonald, Darren J Shaw
The growth of the maxillary canine teeth of the babirusa (genus Babyrousa) was studied on a sample of 149 adult male babirusa skulls from twenty-two international museum and private collections. Skulls from Buru, Sulawesi and the Togian Islands were represented. The continuous growth process was summarised into five stages ('A'-'E') according to the position of the tip of the tooth over the bones of the skull. The supracutaneous portion of the tooth grew in a curve-linear fashion dorso-caudally, and was orientated such that the tips grew towards the midline of the cranium...
May 8, 2018: Comptes Rendus Biologies
Rosa Carotenuto, Margherita Tussellino
At the beginning of diplotene, the oocyte of Xenopus laevis is a cell of about 10-20 microns destined to increase 10,000-fold its size when the oocyte becomes filled with yolk platelets and has accumulated a great number of pigment granules in a half of its periphery. Its internal architecture is gradually accomplished during growth because of several factors, especially because of cytoskeletal changes. In the fully-grown oocyte, the cytoskeleton appears to sustain the eccentrically located germinal vesicle through arms radiating from the cortex to the germinal vesicle, a unique organization not to be found in other Amphibians...
April 25, 2018: Comptes Rendus Biologies
Pablo Castillejo, Susana Chamorro, Luis Paz, Carla Heinrich, Ivonne Carrillo, Jose G Salazar, Juan C Navarro, Eduardo A Lobo
Epilithic diatom communities are particularly suitable for the evaluation of freshwater quality. In Ecuador, however, no water quality index includes this biotic parameter. This work is the first attempt in the country to determine the composition of epilithic diatom communities associated with different degrees of eutrophication. This was accomplished by measuring physical, chemical and microbiological variables at five sampling sites along the Pita River, Ecuador, from August to December 2016. The results indicate a clear gradient of eutrophication from sampling sites P1 (good water) in the upper reaches to P5 (bad water) located in the lower reaches...
April 11, 2018: Comptes Rendus Biologies
Denis Allemand, Paola Furla
Cnidarians (corals and sea anemones) harbouring photosynthetic microalgae derive several benefits from their association. To allow this association, numerous symbiotic-dependent adaptations in both partners, resulting from evolutionary pressures, have been selected. The dinoflagellate symbionts (zooxanthellae) are located inside a vesicle in the cnidarian host cell and are therefore exposed to a very different environment compared to the free-living state of these microalgae in terms of ion concentration and carbon content and speciation...
April 9, 2018: Comptes Rendus Biologies
Anne-Gaëlle Goubet, Romain Daillère, Bertrand Routy, Lisa Derosa, Paula M Roberti, Laurence Zitvogel
Accumulating evidence points to the impact of the gut microbiota in regulating various chronic inflammatory disorders such as cancers. The intestinal microbiome is not only influencing the spontaneous course of colon malignancies but also acts at distant sterile sites of neoplasia, mostly playing a detrimental role. By providing microbial-associated molecular patterns and potentially antigens sharing molecular mimicry with tumor antigens, our commensals modulate the local and the systemic immune tonus, eventually influencing tumor microenvironment...
April 6, 2018: Comptes Rendus Biologies
Gérard Eberl
The intestinal microbiota is essential for digestion, the production of physiological metabolites, and defense. More than 1013 bacteria are present in the intestine, inspiring awe as well as fear of potential infections. By definition, the immune system protects us from infection, and is given the task to recognize dangerous pathogens from useful mutualists. Nevertheless, the definition of pathogens and mutualists is often contextual, and the immune system reacts to all types of microbes. In fact, immune reactivity to microbiota is necessary for the development of the immune system...
April 6, 2018: Comptes Rendus Biologies
Karina Bivar Xavier
The mammalian gastrointestinal tract harbors a diverse and complex resident bacterial community, which interacts with the host in many beneficial processes required for optimal host health. We are studying the importance of bacterial cell-cell communication mediated by the interspecies quorum-sensing signal autoinducer-2 (AI-2) in the beneficial properties of the gut microbiota. Our recent work provided the first evidence that AI-2 produced by Escherichia coli can influence the species composition of this community in the mouse gut...
April 6, 2018: Comptes Rendus Biologies
Wilson R Lourenço, Dinh-Sac Pham, Thi-Hang Tran, Thi-Hang Tran
Two new species of scorpion belonging to the family Pseudochactidae and to the genus Vietbocap are described based on specimens collected in the Thien Duong cave, which belongs to the Vom cave system, in the Phong Nha-Ke Bang National Park, Quang Binh Province, Vietnam. The previously described species from this cave, Vietbocap thienduongensis Lourenço & Pham, 2012 was collected in the initial section of the cave (1500 to 1800m from the cave entrance) and proved to be a true troglobitic element. The diagnosis of this species, only known from males, is completed based on females collected at 750m from the cave entrance...
March 30, 2018: Comptes Rendus Biologies
Philippe Lherminier
We distinguish two types of predations: the predation of matter-energy equals the food chain, and the informative predation is the capture of the information brought by the sexual partners. The cell or parent consumes energy and matter to grow, multiply and produce offspring. A fixed amount of resources is divided by the number of organisms, so individual growth and numerical multiplication are limited by depletion resources of the environment. Inversely, fertilization does not destroy information, but instead produces news...
March 29, 2018: Comptes Rendus Biologies
Massimo Venditti, Chiara Fasano, Alessandra Santillo, Francesco Aniello, Sergio Minucci
Dishevelled-associated activator of morphogenesis 1 (DAAM1) is a protein belonging to the formin family, which regulates, together with the small GTPase RhoA, the nucleation and the assembly of actin fibres through Wnt-Dishevelled PCP pathway. Its role has been investigated in essential biological processes, such as cell polarity, movement and adhesion during morphogenesis and organogenesis. In this work, we studied the expression of DAAM1 mRNA and protein by PCR and Western blot analyses and its co-localization with actin in adult mouse seminal vesicles by immunofluorescence...
March 20, 2018: Comptes Rendus Biologies
Alain Dejean, Arthur Compin, Maurice Leponce, Frédéric Azémar, Camille Bonhomme, Stanislas Talaga, Laurent Pelozuelo, Yann Hénaut, Bruno Corbara
In an inundated Mexican forest, 89 out of 92 myrmecophytic tank bromeliads (Aechmea bracteata) housed an associated ant colony: 13 sheltered Azteca serica, 43 Dolichoderus bispinosus, and 33 Neoponera villosa. Ant presence has a positive impact on the diversity of the aquatic macroinvertebrate communities (n=30 bromeliads studied). A Principal Component Analysis (PCA) showed that the presence and the species of ant are not correlated to bromeliad size, quantity of water, number of wells, filtered organic matter or incident radiation...
March 19, 2018: Comptes Rendus Biologies
Sara Falvo, Gabriella Chieffi Baccaria, Giuseppe Spaziano, Luigi Rosati, Massimo Venditti, Maria Maddalena Di Fiore, Alessandra Santillo
The Harderian gland (HG) of the rat (Rattus norvegicus) secretes copious amounts of lipids, such as cholesterol. Here we report a study of the expressions of the StAR protein and key steroidogenic enzymes in the HG of male and female rats. The objective of the present investigation was to ascertain (a) whether the rat HG is involved in steroid production starting with cholesterol, and (b) whether the pattern of gene and protein expressions together with the enzymatic activities display sexual dimorphism. The results demonstrate, for the first time, the expression of StAR gene and protein, and Cyp11a1, Hsd3b1, Hsd17b3, Srd5a1, Srd5a2 and Cyp19a1 genes in the rat HG...
March 2018: Comptes Rendus Biologies
Yann Hénaut, Bruno Corbara, Frédéric Azémar, Régis Céréghino, Olivier Dézerald, Alain Dejean
Cupiennius salei (Ctenidae) individuals frequently live in association with tank bromeliads, including Aechmea bracteata, in Quintana Roo (Mexico). Whereas C. salei females without egg sacs hunt over their entire host plant, females carrying egg sacs settle above the A. bracteata reservoirs they have partially sealed with silk. There they avoid predators that use sight to detect their prey, as is known for many bird species. Furthermore, if a danger is more acute, these females dive with their egg sacs into the bromeliad reservoir...
March 2018: Comptes Rendus Biologies
Tousheng Huang, Huayong Zhang, Liming Dai, Xuebing Cong, Shengnan Ma
This research investigates the formation of banded vegetation patterns on hillslopes affected by interactions between sediment deposition and vegetation growth. The following two perspectives in the formation of these patterns are taken into consideration: (a) increased sediment deposition from plant interception, and (b) reduced plant biomass caused by sediment accumulation. A spatial model is proposed to describe how the interactions between sediment deposition and vegetation growth promote self-organization of banded vegetation patterns...
March 2018: Comptes Rendus Biologies
Nicolas Bacaër
This study focuses on the extinction rate of a population that follows a continuous-time multi-type branching process in a random environment. Numerical computations in a particular example inspired by an epidemic model suggest an explicit formula for this extinction rate, but only for certain parameter values.
March 2018: Comptes Rendus Biologies
Bruno Corbara, Pablo Servigne, Alain Dejean, James M Carpenter, Jérôme Orivel
In French Guiana, the arboreal nests of the swarm-founding social wasp Protopolybia emortualis (Polistinae) are generally found near those of the arboreal dolichoderine ant Dolichoderus bidens. These wasp nests are typically protected by an envelope, which in turn is covered by an additional carton 'shelter' with structure resembling the D. bidens nests. A few wasps constantly guard their nest to keep D. bidens workers from approaching. When alarmed by a strong disturbance, the ants invade the host tree foliage whereas the wasps retreat into their nest...
March 2018: Comptes Rendus Biologies
Yan Qun Peng, Ling Ling Fan, Fu Ying Mao, Yun Sheng Zhao, Rui Xu, Yu Jie Yin, Xin Chen, De Guang Wan, Xin Hui Zhang
Polygala tenuifolia Willd. is an important protected species used in traditional Chinese medicine. In the present study, amplified fragment length polymorphism (AFLP) markers were employed to characterize the genetic diversity in wild and cultivated P. tenuifolia populations. Twelve primer combinations of AFLP produced 310 unambiguous and repetitious bands. Among these bands, 261 (84.2%) were polymorphic. The genetic diversity was high at the species level: percentage of polymorphic loci (PPL)=84.2%, Nei's gene diversity (h)=0...
March 2018: Comptes Rendus Biologies
Rafael N Carvalho
Paradiscocyrtus neglectus Mello-Leitão, 1927 is here redescribed and for the first time illustrated. A neotype is proposed to clarify the taxonomic status of this species and to differentiate it from the other two species of Paradiscocyrtus and related genera (e.g., Discocyrtus). Two junior synonyms of this species, currently allocated in Discocyrtus Holmberg, 1876 are here detected. This harvestman is endemic from areas above 2000 meters of altitude, occurring in the Campos Rupestres montane savannas terrestrial eco-region in the states of Minas Gerais and Rio de Janeiro, Brazil...
March 2018: Comptes Rendus Biologies
Jie Jiao, Xiangrong Jia, Pei Liu, Qiaomei Zhang, Feng Liu, Cunde Ma, Pengzhou Xi, Zongsuo Liang
Morphological markers as well as two types of molecular markers, inter-sample sequence repeat (ISSR) and start codon targeted (SCoT) are suitable for species identification of the polygonati rhizoma germplasms. In this paper, we adopted these methods for the identification of rhizomes collected from 47 areas in China. Based on their morphological characters, the collected germplasms were classified into two populations, one with alternate leaf arrangement and the other with verticillate leaf arrangement, and they were comprised of five species and fourteen subgroups...
February 2018: Comptes Rendus Biologies
Annam Pavan-Kumar, Rajan Kumar, Pranali Pitale, Kang-Ning Shen, Philippe Borsa
The blue-spotted maskray, previously N. kuhlii, consists of up to eleven lineages representing separate species. Nine of these species (N. australiae, N. bobwardi, N. caeruleopunctata, N. malaccensis, N. moluccensis, N. orientale, N. vali, N. varidens, N. westpapuensis) have already been formally described and two (Indian Ocean maskray and Ryukyu maskray) remain undescribed. Here, the Indian Ocean maskray is described as a new species, Neotrygon indica sp. nov. Specimens of the new species were generally characterized on their dorsal side by a moderately large number of small ocellated blue spots, a low number of medium-sized ocellated blue spots, the absence of large ocellated blue spots, a high number of dark speckles, a few dark spots, and a conspicuous occipital mark...
February 2018: Comptes Rendus Biologies
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