Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 20

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
A new osmylid neuropteran insect Archaeosmylidia fusca gen. et sp. nov. is described from the Middle Jurassic locality of Daohugou (Inner Mongolia, China). Its forewing venation differs from that of other hitherto known osmylids by a set of plesiomorphic features. This genus is considered here as representing a basal group of Osmylidae. The Permian–Triassic family Archeosmylidae comprises the genera Archeosmylus, Babykamenia, and Lithosmylidia. Archaeosmylidia and Archeosmylidae share the few−branched CuP, the absence of zigzag vein pattern, and the scarcity of the crossveins in the radial space.Weestimate that Osmylidae might have originated in the Triassic from some “archeosmylid−like” ancestor.
Drought stress causes yield loss in rice by inhibiting panicle exsertion which is driven by peduncle elongation near flowering. To elucidate the mechanism of peduncle elongation, we examined the drought sensitivity of corresponding genes encoding xyloglucan endotransglycosylase/hydrolase (XTH), a cell wall-loosening enzyme essential for cell elongation in the peduncle elongation zone at heading stage. When drought was imposed 6 days before heading, peduncle elongation rate (PER) was inhibited significantly at heading and 1 day after heading. Eleven OsXTH genes were isolated and their expression in rice peduncle determined. The expression of 11 OsXTH genes showed different patterns of response to drought stress. OsXTH3 was completely suppressed by drought. Transcript levels for OsXTH19, -20, -24, -27 and -28 genes were markedly down-regulated at a series of drought stresses. By contrast, OsXTH5 was up-regulated. Also, the behavior of leaf gas exchange and peduncle abscisic acid (ABA) level was determined under drought conditions. The results indicated that stomatal conductance was 83% lower than that in control plants and peduncle ABA increased ninefold with drought stress. Peduncle ABA content correlated highly with leaf stomatal conductance and PER (r = 0.85** and 0.88**). The expression in OsXTH5, -19, -20, -24 and -28, corresponded to changes in PER and ABA. We conclude that ABA could be involved in inducing the retardation of PER and changes of expression of OsXTH genes. OsXTH5, -19, -20, -24 and -28 genes may play a role in rice peduncle elongation. In addition, interactions among genes may affect PER under drought.
C-repeat/dehydration-responsive element binding factors (CBF/DREBs) play a vital regulatory role in abiotic stress responses in plants. We isolated the ZmDBP4 gene, a member of the A-1 subgroup of the CBF/DREB subfamily, from maize seedlings. A ZmDBP4::hGFP fusion protein was found to localize into the nucleus upon introduction into epidermal onion cells. As a trans-acting factor, the ZmDBP4 protein activated CRT/DRE-containing genes under normal growth conditions in transgenic Arabidopsis plants. ZmDBP4 transcription was highly activated by cold and moderately by drought in ABA-independent manner. Isolation of the ZmDBP4 promoter revealed some cis-acting elements responding to stresses. Overexpression of ZmDBP4 improved drought and cold-stress tolerance in transgenic Arabidopsis plants. Our results suggested that ZmDBP4 produces a functional factor that may play a regulatory role in abiotic stress response.
Examinations were carried out in 46 intensive farms in northern China to investigate avian Chlamydophila psittaci. Five hundred and twenty-five avian sera were selected for examining antibodies to C. psittaci by ELISA. One hundred and fifty-five clinical samples from throat swabs and oviduct tissues were tested for the presence of chlamydial antigen using IDEIA™ PCE chlamydia dual amplification immunoassay, and 60 samples were tested by ompA gene-based PCR. C. psittaci antibodies were detected in 387 (77.8%) out of 525 serum samples, with seroprevalences ranging from 50% to 100%. Among the tested samples, 98/150 (65.3%) in broilers, 173/210 (82.3%) in ducks, and 116/165 (70.3%) in laying hens were detected to be positive, respectively. Using PCE-ELISA test kits, in 91 out of 155 clinical samples the presence of antigen was confirmed, while 64 samples were negative. Forty-three PCR's were tested as positive out of 60 samples, while 17 samples were confirmed to be negative. Both higher positive antibodies and the presence of antigens were found in avian flocks associated with typical clinical signs suggestive of chlamydiosis. This study showed a severe prevalence of C. psittaci among different species of domestic birds in China.
The yarkand hareLepus yarkandensis Günther, 1875 is one of the endemic mammals in China. We used mitochondrial control region (D-loop) sequences to investigate the genetic variation, population structure and phylogeography of the Yarkand hare from Xinjiang Uighur Autonomous Region. The Yarkand hare holds a high level of haplotype diversity in most populations. In contrast, we found a relatively low level of gene diversity in Niya and Shule populations. The pairwise mismatch distribution suggested a pattern of population expansion. Fu’s test of neutrality was significant for the total population (F s=−10.458), which also suggested a recent population expansion. The pattern of diversification among populations was not consistent with its geographic distributions. Significant divergence was found among some populations, however, no significant divergence among other populations. The results indicate some degree of dispersal of individuals may exist among populations in recent history. Due to past isolation and habitat fragmentation, genetic variation was reduced within populations and division among populations increased. In order to conserve genetic diversity of the Yarkand hare in isolated populations, in the future, it may be advisable to translocate individuals between isolated populations to maintain current levels of genetic variation.
Multivariate statistical techniques, hierarchical cluster analysis (HCA), and principal component analysis (PCA) integrating graphical method (Piper trilinear graphical diagram) were applied to the factor identification of ground water quality in a coastal aquifer, Fujian province, South China. Ground water samples were collected at 12 sites in January (dry season) and July 2011 (wet season). Eleven ground water quality parameters (pH, TH, TDS, Ca²⁺, Mg²⁺, Na⁺ , Cl⁻, SO₄²⁻, HCO₃⁻, NO₃⁻, Mn) were selected in order to perform multivariate statistical analysis. During both the past-monsoon and the summer seasons, PCA results revealed the existence of three significant principal components revealing how processes like salinization, water-rock interaction, and anthropogenic pollution influence ground water quality. Three factors which together explain 90.3% and 83.3% of the total variance in the summer and post-monsoon dataset were retained and interpreted. Cluster analysis using the Ward method with squared Euclidean distance measure was performed, which indicated the distribution of the studied wells according to their water quality. Water samples from 12 wells were clustered into three distinct groups to depict different hydrochemical facies. The results proved that multivariate analysis methods like HCA and PCA could be useful for evaluating ground water pollution and identifying ground water hydrochemistry.
A new tealliocaridid eumalacostracan is described from the Late Carboniferous Tupo Formation (Ningxia, China). Laevitealliocaris xiaheyanensis gen. et sp. nov. is represented by a single specimen, characterised by the possession of a short rostrum without dorsal spine, a short postcervical carina and only one weak branchial carina, both tuberculate, and a short sixth pleonal somite. This is the first unequivocal record of tealliocaridids outside Euramerica, which occurrence along the eastern inner margin of the Palaeotethys suggests that these crustaceans were more widely distributed than previously recognised, very likely extending to the whole intertropical area. The new occurrence demonstrates that tealliocaridids had strong dispersal capacities, interestingly challenging their affinities with peracarids, which today do not have free-living larvae, unlike decapod crustaceans.
RT-qPCR is a widely used method in gene expression and transcriptome studies. Normalization based on reference genes is necessary to accurately analyze RtqPCR data. Thus, an accurate and systematic evaluation of these reference genes before experiments are conducted is necessary. In this study, 18 candidate reference genes were evaluated under various experimental conditions covering a range of tissue types and cultivars, NaCl, CaCl2 and temperature treatments, hormones (6-BA, ABA and NAA) and a set of osmotic stress (mannitol and PEG6000) treatments. Gene expression across 48 pear samples was evaluated using geNorm, NormFinder and BestKeeper statistical algorithms. Actin2/7 (ACT2/7), ubiquitin extension protein (UBI) and Yellow-leaf-specific gene 8 (YLS8) exhibited the most stable expression across all the pear samples tested. While in the other experimental groups, different sets of samples had their own best reference genes. In addition, the gene expression of PbCBL7, a member of the calcineurin B-like protein, was measured across all the 48 samples using the best three reference genes, it displayed variation in gene expression across different tissues and cultivars, and exhibited diverse up- or down-regulated expression patterns under various treatments, which indicate that PbCBL7 may play a role in response to specific abiotic stress in pear. These results are valuable for future research on gene expression and abiotic stress tolerance in pear.
Angiopoietin-1 (Ang-1) belongs to a novel family of endothelial growth factors that function as ligands for an endothelialspecific receptor tyrosine kinase (Tie-2). The Ang-1/Tie-2 system may contribute to angiogenesis and vascular remodeling by mediating interactions of endothelial cells with smooth muscle cells and pericytes. The spatial distribution and temporal expression of Ang-1 and Tie-2 in the rat brain were studied following collagenase-induced intracerebral hemorrhage (ICH), by immunohistochemistry and reverse transcription-polymerase chain (RT-PCR) analysis, respectively. Immunohistochemical analysis revealed that some Ang-1 or Tie-2-positive dilated vessels resided around the hematoma and extended into the clot. RT-PCR analysis showed that Ang-1 and Tie-2 mRNA signal was detected at 2 days and persisted for 28 days after ICH. These findings suggest that ICH could lead to upregulation of Ang-1 and the receptor Tie-2 mRNA.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.