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61.
Two hundred and eight taxa of bryophytes, including two hundred and seven species, are reported from extreme northern Yukon. Five hepatic and eighteen moss taxa represent new records for the Yukon, which areAnastrophyllum hellerianum (Nees) Schust.,Scapania degenii Schiffn. in K. Müll.,Riccardia palmata (Hedw.) Carruth.,Mannia sibirica (K. Müll.) Frye & Clark,Sauteria alpina (Nees) Nees,Sphagnum orientale Savich,Dicranum spadiceum Zett.,Anoectangium aestivum (Hedw.) Mitt.,Barbula coreensis (Card.) Saito,B. platyneura C. Müll. & Kindb.,Pottia obtusifolia C. Müll.,Splachnum vasculosum Hedw.,Bryum acutiforme Limpr. ex Hag.,B. bimum (Brid.) Turn.,B. intermedium (Brid.) Bland.,B. neodamense Itzigs.,Cinclidium latifolium Lindb.,Timmia comata Lindb. & Arn.,Orthothecium acuminatum Bryhn,Cratoneuron arcticum Steere,Drepanocladus brevifolius (Lindb.) Warnst.,D. intermedius (Lindb.) Warnst., andD. lycopodioides (Brid.) Warnst. Many of the other collections represent significant extensions of ranges to the arctic sector of the Yukon Territory. 相似文献
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Shoot apices of Spinacia oleracea plants have been induced toflower either by: (a) subjecting leaves to 24 h long day, or(b) exposure to a short photoperiod but displaced by 8 h (displacedshort day) in the usual 24 h short-day cycle, or (c) exposureto low temperature (5 °C) during the dark period of thenormal short day. A quantitative cytochemical assay of pentosephosphate pathway activity during floral induction indicatesan approximate doubling of the rate of activity when comparedto that of vegetative apices (short day) (21 °C). Exposure to either low temperature, or a displaced short photoperiodstimulates pentose phosphate pathway activity in the shoot apexin a manner similar to that seen by long-day induction. Thischange in metabolic activity is accompanied by changes in theshape of the shoot apex which resembles that seen at an earlystage during floral induction. Spinacia oleracea, pentose phosphate pathway, shoot apex, glucose-6-phosphate dehydrogenase, floral induction, chilling, displaced short day 相似文献
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Hamza Gadhoumi Martinez-Rojas Enriqueta Tounsi Moufida Saidani Hayouni EL Akrem 《Biology Bulletin》2021,48(6):667-672
Biology Bulletin - Erodium glaucophyllum, Erodium hirtum and Erodium guttatum were medicinal herbs from a southern Mediterranean known for its health benefits. There is a strong demand for the find... 相似文献
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Polly J Phillips-Mason Sonya EL Craig Susann M Brady-Kalnay 《Cell Adhesion & Migration》2011,5(4):298-305
Dissolution of cell-cell adhesive contacts and increased cell-extracellular matrix adhesion are hallmarks of the migratory and invasive phenotype of cancer cells. These changes are facilitated by growth factor binding to receptor protein tyrosine kinases (RTKs). In normal cells, cell-cell adhesion molecules (CAMs), including some receptor protein tyrosine phosphatases (RPTPs), antagonize RTK signaling by promoting adhesion over migration. In cancer, RTK signaling is constitutive due to mutated or amplified RTKs, which leads to growth factor independence or autonomy. An alternative route for a tumor cell to achieve autonomy is to inactivate cell-cell CAMs such as RPTPs. RPTPs directly mediate cell adhesion and regulate both cadherin-dependent adhesion and signaling. In addition, RPTPs antagonize RTK signaling by dephosphorylating molecules activated following ligand binding. Both RPTPs and cadherins are downregulated in tumor cells by cleavage at the cell surface. This results in shedding of the extracellular, adhesive segment and displacement of the intracellular segment, altering its subcellular localization and access to substrates or binding partners. In this commentary we discuss the signals that are altered following RPTP and cadherin cleavage to promote cell migration. Tumor cells both step on the gas (RTKs) and disconnect the brakes (RPTPs and cadherins) during their invasive and metastatic journey.Key words: receptor protein tyrosine kinase, receptor-like protein tyrosine phosphatase, cadherins, cell adhesion, signal transduction, phospholipase C gamma, protein kinase C, catenins, IQGAP1 protein, regulated intramembrane proteolysis 相似文献
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The present study was initiated to determine whether dietary supplemental L-carnitine and ascorbic acid affect growth performance, carcass yield and composition, abdominal fat and plasma L-carnitine concentration of broiler chicks reared under normal and high temperature. During the experiment, two temperature regimes were employed in two experimental rooms, which were identical but different in environmental temperature. The regimes were thermoneutral (20-22°C for 24 h) or recycling hot (34-36°C for 8 h and 20-22°C for 16 h). One-day-old broiler chicks (ROSS) were used in the experiment. A 2 x 2 x 2 factorial arrangement was employed with two levels (0 and 50 mg/kg) of supplemental L-carnitine and two levels (0 or 500 mg/kg) of supplemental ascorbic acid in drinking water under thermoneutral or high temperature regimes. Body weight gain was affected by high temperature. However, body weight gain was significantly improved in animals receiving supplemental L-carnitine, ascorbic acid or L-carnitine + ascorbic acid compared to animals receiving unsupplemented diet under high temperature. On the other hand, supplemental L-carnitine or L-carnitine + ascorbic acid reduced body weight gain under thermoneutral condition. Supplemental ascorbic acid significantly improved feed conversion efficiency, the improvement was relatively greater under high temperature. The L-carnitine content in the plasma was higher in the groups receiving supplemental L-carnitine and ascorbic acid under high temperature, while broilers fed supplemental L-carnitine and ascorbic acid had a decreased level of plasma L-carnitine concentration under normal temperature. It is concluded that dietary supplemental L-carnitine or L-carnitine + ascorbic acid may have positive effects on body weight gain, carcass weight under high temperature conditions. 相似文献
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