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991.
Monogononts reproduce by parthenogenesis punctuated by events of mixis that generate ‘resting eggs’, which actually are embryos
whose development is arrested. We document the nuclei number and position of the resting eggs of nine rotifer species (Brachionus plicatilis, B. calyciflorus, B. manjavacas, Plationus patulus, Epiphanes senta, E. chihuahuaensis, Rhinoglena frontalis, Lecane bulla and Sinantherina socialis) in the attempt to assess the stage at which dormant embryos are arrested. The morphology of the entire embryos was reconstructed
visualising nuclear DNA using confocal microscopy, and their developmental stage identified. Two groups of species were identified:
dormant embryos of one group possessed on average less than 30 nuclei, with low variation within and between species, and
the stage may correspond to early gastrula; embryos in the second group contain relatively more nuclei, averaging around 40–60,
with higher variation within species. The two groups of species seem not to reflect any phylogenetic relationship. Consequences
of the dormant embryo stages are discussed. 相似文献
992.
Serotonin is a neurotransmitter present throughout animal kingdom that controls a number of crucial functions in different
taxa. In this study we document the role of serotonin in a bdelloid rotifer, Macrotrachela quadricornifera. Following life table experimental protocol, we recorded age-specific fecundity and survival rates of cohorts that received
WAY 100135 maleate, a selective antagonist of the serotonin receptor 1A. The antagonist was provided from the age of 4 days
(age at first reproduction) until death to one cohort group, and during 15 days to another group. Both groups were cultivated
regularly, and their life history traits were recorded. Treated rotifers continued to produce eggs, but most eggs were never
oviposited and eventually ruptured the mother’s body wall. The retained eggs, being parthenogenetic began embryogenesis and
some could hatch inside the mother’s body cavity (pseudocoel). When WAY was suspended, most treated rotifers oviposited all
their eggs. About 75% of these eggs developed, but development was 1–2 days longer than in controls. Most newborns reached
sexual maturity, although their maturity was delayed as well. Eggs produced after WAY suspension hatched as much as the controls
(~100%). WAY possibly did not affect egg production, but prevented regular oviposition. Nevertheless, viability was reduced
and development took longer during WAY treatment. Results suggest that in bdelloid rotifers serotonin is involved in the control
of egg laying and development, among other features, as it does in most animals, from nematodes to chordates. 相似文献
993.
David Pecqueur Francesca Vidussi Eric Fouilland Emilie Le Floc’h Sebastien Mas Christian Salles Marie-George Tournoud Behzad Mostajir 《Hydrobiologia》2011,673(1):13-27
Episodic river flash floods, characteristic of Mediterranean climates, are suspected to greatly affect the functioning of
microbial food webs. For the first time, the abundance, biomass and diversities of microbial food web components were studied
before and during 4 consecutive days after a flash flood that occurred in November 2008, in the surface waters of five stations
along a salinity gradient from 20 to 36 in the Thau lagoon. Eukaryotic pico- and nanophytoplankton were discharged from the
river into the lagoon and increased by 30- and 70-fold, respectively. Bacteria increased by only 2-fold in the lagoon, from
around 4–8 × 106 cells ml−1, probably benefiting from river nutrient input. Chlorophyll a increased 4-fold, and pigment biomarkers showed that the dinophyceae, prasinophyceae and prymnesiophyceae were sensitive
to the flood perturbation, whereas the bacillariophyceae, cryptophyceae and chlorophyceae were resistant and/or transported
to the lagoon from the river. Predator responses were more complex as total heterotrophic flagellate abundance decreased slightly,
whereas those of specific naked ciliates increased, particularly for Uronema sp. The flood also induced a specific change in diversity, from a community dominated by Strobilidium spiralis to a community dominated by Uronema sp. The tintinnid community was particularly sensitive to the flood event as the abundance of all species decreased greatly.
The high increases in biomass, mainly brought by the river during the flood, could have eventually sedimented to the benthic
layer and/or been transported further into the lagoon, supporting the pelagic food web, or have even been exported to the
Mediterranean Sea. 相似文献
994.
Ciaramella A Spalletta G Bizzoni F Salani F Caltagirone C Bossù P 《Cellular immunology》2011,269(2):82-89
Dendritic cells (DCs) are central in regulating both innate and acquired immunity, but their possible age-related functional modifications are still unclear. Here we have analyzed the effect of age on LPS-treated monocyte-derived DCs (MDDCs). A negative correlation between age and cell expression of ICAM-1, CD25 and IL-10 was observed in a group of healthy donors. This has been confirmed by a significantly reduced expression of the same molecules in cells of subgrouped elderly versus younger individuals. On the contrary, a positive correlation between age and cell expression of IL-6 and IL-18 has been reported in all the subjects and further supported by a significant increase of the two pro-inflammatory cytokines in cells of elderly versus young subjects.Our data indicate that aging can impair the expression of ICAM-1 and CD25 and skew the production of cytokines, including IL-18, which concur to make a pro-inflammatory milieu. Altogether, the present results point to additional molecules whose role might be relevant in immunosenescence of human DCs, confirming that these cells undergo functional changes during aging. 相似文献
995.
996.
WCI,a novel wheat chymotrypsin inhibitor: purification,primary structure,inhibitory properties and heterologous expression 总被引:1,自引:0,他引:1
Di Maro A Farisei F Panichi D Severino V Bruni N Ficca AG Ferranti P Capuzzi V Tedeschi F Poerio E 《Planta》2011,234(4):723-735
A novel chymotrypsin inhibitor, detected in the endosperm of Triticum aestivum, was purified and characterized with respect to the main physical–chemical properties. On the basis of its specificity, this
inhibitor was named WCI (wheat chymotrypsin inhibitor). WCI is a monomeric neutral protein made up of 119 residues and molecular
mass value of 12,933.40 Da. Automated sequence and mass spectrometry analyses, carried out on several samples of purified
inhibitor, evidenced an intrinsic molecular heterogeneity due to the presence of the isoform [des-(Thr)WCI], accounting for
about 40% of the total sample. In vitro, WCI acted as a strong inhibitor of bovine pancreatic chymotrypsin as well as of chymotryptic-like
activities isolated from the midgut of two phytophagous insects, Helicoverpa armigera (Hüb.) and Tenebrio molitor L., respectively. No inhibitory activities were detected against bacterial subtilisins, bovine pancreatic trypsin, porcine
pancreatic elastase or human leukocyte elastase. The primary structure of WCI was significantly similar (45.7–89.1%) to those
of several proteins belonging to the cereal trypsin/α-amylase inhibitor super-family and showed the typical sequence motif
of this crowed protein group. The cDNA of the inhibitor (wci-cDNA) was isolated from wheat immature caryopses and employed to obtain a recombinant product in E. coli. Experimental evidences indicated that the recombinant inhibitor was localized in the inclusion bodies from which it was
recovered as soluble and partially active protein by applying an appropriate refolding procedure. WCI reactive site localization,
as well as its inhibitory specificity, was investigated by molecular modeling approach. 相似文献
997.
Zenoni S Fasoli M Tornielli GB Dal Santo S Sanson A de Groot P Sordo S Citterio S Monti F Pezzotti M 《The New phytologist》2011,191(3):662-677
? Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. ? PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. ? The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. ? These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism. 相似文献
998.
Partial migration in roe deer: migratory and resident tactics are end points of a behavioural gradient determined by ecological factors 总被引:1,自引:0,他引:1
Francesca Cagnacci Stefano Focardi Marco Heurich Anja Stache A. J. Mark Hewison Nicolas Morellet Petter Kjellander John D. C. Linnell Atle Mysterud Markus Neteler Luca Delucchi Federico Ossi Ferdinando Urbano 《Oikos》2011,120(12):1790-1802
Ungulate populations exhibiting partial migration present a unique opportunity to explore the causes of the general phenomenon of migration. The European roe deer Capreolus capreolus is particularly suited for such studies due to a wide distribution range and a high level of ecological plasticity. In this study we undertook a comparative analysis of roe deer GPS location data from a representative set of European ecosystems available within the EURODEER collaborative project. We aimed at evaluating the ecological factors affecting migration tactic (i.e. occurrence) and pattern (i.e. timing, residence time, number of migratory trips). Migration occurrence varied between and within populations and depended on winter severity and topographic variability. Spring migrations were highly synchronous, while the timing of autumn migrations varied widely between regions, individuals and sexes. Overall, roe deer were faithful to their summer ranges, especially males. In the absence of extreme and predictable winter conditions, roe deer seemed to migrate opportunistically, in response to a tradeoff between the costs of residence in spatially separated ranges and the costs of migratory movements. Animals performed numerous trips between winter and summer ranges which depended on factors influencing the costs of movement such as between‐range distance, slope and habitat openness. Our results support the idea that migration encompasses a behavioural continuum, with one‐trip migration and residence as its end points, while commuting and multi‐trip migration with short residence times in seasonal ranges are intermediate tactics. We believe that a full understanding of the variation in tactics of temporal separation in habitat use will provide important insights on migration and the factors that influence its prevalence. 相似文献
999.
Basini G Grasselli F Bussolati S Baioni L Bianchi F Musci M Careri M Mangia A 《Steroids》2011,76(13):1433-1436
We previously demonstrated the presence of 2-methoxyestradiol (2-ME) in swine follicular fluid. Present study was aimed first of all to investigate if swine granulosa cell produce 2-ME; in addition, we tried to assess a potential effect of hypoxia in modulating 2-ME output. Finally, we explored the effect of 2-ME in an angiogenesis bioassay set up in our lab. Our data show that cultured granulosa cells are able to produce 2-ME; interestingly, the secretion of the hormone appeared to be stimulated by hypoxia. Angiogenesis bioassay points out that 2-ME displays an inhibitory effect on neovascularisation. Therefore our data suggest that 2-ME could be a local effector in determining the fine tuning responsible for follicle angiogenesis. These data deserve special attention since the ovary is a valuable experimental model in angiogenesis research. 相似文献
1000.
Eloe EA Malfatti F Gutierrez J Hardy K Schmidt WE Pogliano K Pogliano J Azam F Bartlett DH 《Applied and environmental microbiology》2011,77(22):8145-8153
Cultivated psychropiezophilic (low-temperature- and high-pressure-adapted) bacteria are currently restricted to phylogenetically narrow groupings capable of growth under nutrient-replete conditions, limiting current knowledge of the extant functional attributes and evolutionary constraints of diverse microorganisms inhabiting the cold, deep ocean. This study documents the isolation of a deep-sea bacterium following dilution-to-extinction cultivation using a natural seawater medium at high hydrostatic pressure and low temperature. To our knowledge, this isolate, designated PRT1, is the slowest-growing (minimal doubling time, 36 h) and lowest cell density-producing (maximal densities of 5.0 × 106 cells ml−1) piezophile yet obtained. Optimal growth was at 80 MPa, correlating with the depth of capture (8,350 m), and 10°C, with average cell sizes of 1.46 μm in length and 0.59 μm in width. Through detailed growth studies, we provide further evidence for the temperature-pressure dependence of the growth rate for deep-ocean bacteria. PRT1 was phylogenetically placed within the Roseobacter clade, a bacterial lineage known for widespread geographic distribution and assorted lifestyle strategies in the marine environment. Additionally, the gene transfer agent (GTA) g5 capsid protein gene was amplified from PRT1, indicating a potential mechanism for increased genetic diversification through horizontal gene transfer within the hadopelagic environment. This study provides a phylogenetically novel isolate for future investigations of high-pressure adaptation, expands the known physiological traits of cultivated members of the Roseobacter lineage, and demonstrates the feasibility of cultivating novel microbial members from the deep ocean using natural seawater. 相似文献