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NAM SO GREGORY E. MAES FILIP A. M. VOLCKAERT 《Biological journal of the Linnean Society. Linnean Society of London》2006,89(4):719-728
Larvae of the sutchi catfish Pangasianodon hypophthalmus were collected during peak downstream drift in the Lower Mekong river on four occasions over an 8-week period during the 2003 spawning season, and genotyped using seven microsatellite loci. We provide evidence for several heterogeneous groups within and among the temporally discrete larval peak samples. Strong evidence for a significant deficit of heterozygotes was observed for each larval sample and the pooled sample, possibly due to population admixture. Although individual-based assignment tests suggested that each larval peak sample was admixed, significant but low genetic differentiation was observed among larval samples ( F ST = 0.0052, P < 0.01). The lack of significant relatedness confirms the multifamily composition of each larval group, excluding family bias to explain the observed genetic heterogeneity. Both the entire larval peak and each temporally separated larval peak originated from spawning groups with heterogeneous allelic composition involving several distinct spawning events. We propose three explanations to account for our findings: (1) the ecological match/mismatch hypothesis; (2) the genetic 'sweepstakes' selection hypothesis; and (3) life-history-specific characteristics of the spawning populations. Finally, an intra-annual shift in the contribution of the spawning populations to the larval drift was detected on successive occasions. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 719–728. 相似文献
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The aim of this study was to compare the viability of human osteoblasts cryopreserved with Me2SO to that of fresh human iliac cancellous bone using cell culture techniques. Osteoblasts were obtained by spontaneous outgrowth of human iliac cancellous bone specimens in experiment I. In experiment II, human iliac cancellous bone was frozen with 10% Me2SO at -80 degrees C for 2 weeks and osteoblasts grew spontaneously after thawing at 37 degrees C by removing Me2SO with sucrose. The cells were grown in culture flasks containing DMEM as a culture medium, supplemented with 10% fetal calf serum. They were kept at 37 degrees C in a humidified atmosphere of 95% air and 5% CO2. Cells from the second passage were plated at a density of 5 times 10(3) cells/cm2 in 24-well plates. For detection of viability and differentiation, WST-1 assay, determination of alkaline phosphatase activity, concentration of procollagen I peptide, concentration of osteocalcin, and indirect immunofluorescence for osteopontin, collagen type I, integrin beta1, and fibronectin were applied. Experiments were conducted at four stages of confluence (days 4, 7, 14, and 21 after plating the cells). Based on the results of this study, we conclude that osteoblast-like cells survived cryopreservation and synthesized a range of markers that were consistent with this cell type. 相似文献
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Sang‐Sup SO Tae‐Hwan HWANG Waseem AKRAM Jhong‐Kyung CHOI Jong‐Jin LEE 《Entomological Research》2012,42(3):158-162
The present study relates to a methanol extract of the seed coat of Ginkgo biloba, and tested particularly on the third instar larvae of Spodoptera exigua. The extract was found to have an inhibitory effect on the growth of the larvae besides bringing a change in the nutrient reserves in the body of the insect. Topical application of five different doses of the methanol extract resulted in a mortal effect to third instar larvae of S. exigua that is very much dependent on the dose as well as duration of exposure. Lower doses revealed lower mortality after 24 h of application. At doses of 1.00, 2.00, 4.00, 8.00 and 16.00 ng/larva, mortalities were 9.25, 26.07, 50.32, 56.28 and 92.44%, respectively. The dose for 50% mortality (LD50) of methanol extracts by applied by a topical method with 1 µL of acetone solution was 1.92 ng/larva. Nutrient reserves like protein, glycogen and lipid are known to regulate pupation and adult emergence. These reserves have been found to be lower in treated larvae, indicating the insecticidal role of methanol extracts from G. biloba against third instar larvae of S. exigua. 相似文献
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RICLEF GROLLE MAY LING SO 《Botanical journal of the Linnean Society. Linnean Society of London》2003,142(2):229-235
Riccia fruticulosa O.F.Müll., 1782 from Norway is a valid name, referring to Riccardia palmata (Hedw.) Carruth. In 1785 Dickson misidentified British plants of a blue Metzgeria as R. fruticulosa . The European blue species of Metzgeria is conspecific with M. violacea (Ach.) Dumort., which replaces M. fruticulosa auct. The true origin of the type of Jungermannia violacea Ach., 1805 is probably Tierra del Fuego (rather than Dusky Bay, New Zealand), where the species is widespread. Reports from Australasia, Asia and Africa are all erroneous. The blue colour of Jungermanniales is found only in living plants and is derived from the oil-bodies. In contrast, that of Metzgeria appears only after death; its biological function is unknown. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 142 , 229−235. 相似文献
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Abstract. 1. Larval rearing densities of Hemipyrellia ligurriens (Wiedemann) (Diptera: Calliphoridae) in standardized carrion were manipulated in order to investigate changes in life-history parameters in response to larval competition for food.
2. Competition was of the typical scramble type. Survivorship remained high at densities up to 32 larvae g liver-1 but decreased rapidly as larval density increased further.
3. Emergent adults were undersized with reduced fecundity and longevity. Variations in adult body size apparently reduced the effects of competition on larval mortality.
4. Females of dry weight corresponding to only 10.4% of the potential maximum emerged at the highest rearing densities of 128 larvae g liver-1. However, these females had a nearly four-fold increase in reproductive investment (per unit weight) when compared to the largest individuals.
5. The duration of larval development declined when competition was intense (i.e. at high larval densities).
6. The short adult life of H.ligurriens, combined with the unpredictability of larval habitat availability, may reduce the value of long-range dispersal so that females 'do better' by maintaining reproductive investment despite a concomitant decline in dispersal ability. 相似文献
2. Competition was of the typical scramble type. Survivorship remained high at densities up to 32 larvae g liver
3. Emergent adults were undersized with reduced fecundity and longevity. Variations in adult body size apparently reduced the effects of competition on larval mortality.
4. Females of dry weight corresponding to only 10.4% of the potential maximum emerged at the highest rearing densities of 128 larvae g liver-1. However, these females had a nearly four-fold increase in reproductive investment (per unit weight) when compared to the largest individuals.
5. The duration of larval development declined when competition was intense (i.e. at high larval densities).
6. The short adult life of H.ligurriens, combined with the unpredictability of larval habitat availability, may reduce the value of long-range dispersal so that females 'do better' by maintaining reproductive investment despite a concomitant decline in dispersal ability. 相似文献
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As the human lung is exposed to a variety of microbial pathogens in the environment, a first line of defense is built up by
pulmonary cells like bronchial/alveolar epithelial cells and alveolar macrophages. These cells express several pattern recognition
receptors (PRRs) recognizing highly conserved microbial motifs and initiating the production of chemokines and pro- and anti-inflammatory
cytokines acting as transmembrane or intracellular receptors. This might not only lead to acute but also to chronic inflammation
which is discussed as an underlying mechanism in the pathogenesis of different lung diseases. 相似文献
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Among 73 postnatal ossification centers, sister-sister (SS) corretions involving age at appearance tend to exceed brother-brother (BB) and sister-brother (SB) correlations by an average of 0.16. This excess of SS over BB and SB ossification timing similarity is not a function of type of center, limb or location, and is in accordance with the hypothesis of partial X-linkage. It is estimated that the larger proportion of genetically determined variance in postnatal ossification timing may be attributed to genes on the X chromosome. 相似文献
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Differentiation-associated modulation of heparan sulfate structure and function in CaCo-2 colon carcinoma cells 总被引:3,自引:2,他引:1
Salmivirta M; Safaiyan F; Prydz K; Andresen MS; Aryan M; Kolset SO 《Glycobiology》1998,8(10):1029-1036
Heparan sulfate species expressed by different cell and tissue types differ
in their structural and functional properties. Limited information is
available on differences in regulation of heparan sulfate biosynthesis
within a single tissue or cell population under different conditions. We
have approached this question by studying the effect of cell
differentiation on the biosynthesis and function of heparan sulfate in
human colon carcinoma cells (CaCo-2). These cells undergo spontaneous
differentiation in culture when grown on semipermeable supports; the
differentiated cells show phenotypic similarity to small intestine
enterocytes. Metabolically labeled heparan sulfate was isolated from the
apical and basolateral media from cultures of differentiated and
undifferentiated cells. Compositional analysis of disaccharides, derived
from the contiguous N-sulfated regions of heparan sulfate, indicated a
greater proportion of 2-O- sulfated iduronic acid units and a smaller
amount of 6-O-sulfated glucosamine units in differentiated than in
undifferentiated cells. By contrast, the overall degree of sulfation, the
chain length and the size distribution of the N-acetylated regions were
similar regardless the differentiation status of the cells. The structural
changes were found to affect the binding of heparan sulfate to the long
isoform of platelet-derived growth factor A chain but not to fibroblast
growth factor 2. These findings show that heparan sulfate structures change
during cell differentiation and that heparan sulfate-growth factor
interactions may be affected by such changes.
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