Effect of cellulases on spontaneous fusion of maize protoplasts

Summary The effect of protoplast-isolating enzymes on spontaneous fusion of maize protoplasts (Zea mays L. cv. Black Mexican Sweet) was investigated using a convenient ethidium bromide nuclear staining procedure. After 2–2.5 hour digestion in an enzyme solution containing 1% Cellulysin, 0.5% Rhozyme, and 0.02% Pectolyase Y-23, 50–75% of the protoplasts contained multiple nuclei. The cellulase Cellulysin was identified as the factor causing the spontaneous protoplast fusion; when Cellulysin was replaced by CELF cellulase, most protoplasts were uninucleate. Calcium and other components in the enzyme solution did not affect spontaneous fusion. Cellulysin also increased the percentage of multinucleate protoplasts from rice and asparagus suspensions. Presence of multiple nuclei might affect genetic manipulations involving protoplasts.     

低温胁迫下凤眼莲叶片的适应——脱落酸和可溶性蛋白质含量升高

本文报道低温胁迫下风眼莲叶片脱落酸(ABA)、可溶性蛋白质和水势的测定结果。低温胁迫时脱落酸和可溶性蛋白质含量远高于对照,(前者含量最高可达对照的4倍,后者可达到对照的2.75倍),而且脱落酸和蛋白质含量随温度降低而升高。蛋白质的生物合成抑制剂亚胺环己酮证明,可溶性蛋白质含量升高,原因是有部分是新合成的。在各种低温处理下获得了几乎相同于对照的叶片水势。我们推测:低温胁迫下,脱落酸水平的相应变化不是由于低温诱导水分胁迫所致,而是低温胁迫本身诱导。     

Evidence against the role of alpha 1-adrenoceptor reserve in buffering the inhibitory effect of nifedipine on the contractility of canine vascular smooth muscle

The relationship between the postsynaptic alpha 1-adrenoceptor reserve and the sensitivity of vasoconstriction induced by alpha-adrenoceptor agonists to the dihydropyridine Ca2+ entry blocker nifedipine was investigated in isolated muscle strips of dog mesenteric artery (DMA) and saphenous vein (DSV). The amplitudes of the contractile responses of DMA induced by phenylephrine were the same as those in DSV in the presence and in the absence of extracellular Ca2+. The use of 3 x 10(-9) M phenoxybenzamine to irreversibly block the alpha 1-adrenoceptors revealed a marked difference in the size of the alpha 1-adrenoceptor reserve between DMA (40%) and DSV (7%). In spite of a larger receptor reserve, the contractile responses induced by phenylephrine in DMA were more sensitive to nifedipine compared with those in DSV. These results suggest that the postsynaptic alpha 1-adrenoceptor reserve in vascular smooth muscle, at least in DMA and DSV, does not play an important role in buffering the inhibitory effect of nifedipine on the contractile response to a full agonist of alpha 1-adrenoceptors. Other factors, such as the difference in the membrane depolarizing effect, the ability to utilize intracellular Ca2+ for contraction, and the possible existence of alpha 1-adrenoceptor subtypes, may contribute to the different inhibitory effects of nifedipine on these blood vessels.     

Genome-wide analysis of N1-methyl-adenosine modification in human tRNAs

The N¹-methyl-Adenosine (m¹A58) modification at the conserved nucleotide 58 in the TΨC loop is present in most eukaryotic tRNAs. In yeast, m¹A58 modification is essential for viability because it is required for the stability of the initiator-tRNA^Met. However, m¹A58 modification is not required for the stability of several other tRNAs in yeast. This differential m¹A58 response for different tRNA species raises the question of whether some tRNAs are hypomodified at A58 in normal cells, and how hypomodification at A58 may affect the stability and function of tRNA. Here, we apply a genomic approach to determine the presence of m¹A58 hypomodified tRNAs in human cell lines and show how A58 hypomodification affects stability and involvement of tRNAs in translation. Our microarray-based method detects the presence of m¹A58 hypomodified tRNA species on the basis of their permissiveness in primer extension. Among five human cell lines examined, approximately one-quarter of all tRNA species are hypomodified in varying amounts, and the pattern of the hypomodified tRNAs is quite similar. In all cases, no hypomodified initiator-tRNA^Met is detected, consistent with the requirement of this modification in stabilizing this tRNA in human cells. siRNA knockdown of either subunit of the m¹A58-methyltransferase results in a slow-growth phenotype, and a marked increase in the amount of m¹A58 hypomodified tRNAs. Most m¹A58 hypomodified tRNAs can associate with polysomes in varying extents. Our results show a distinct pattern for m¹A58 hypomodification in human tRNAs, and are consistent with the notion that this modification fine tunes tRNA functions in different contexts.     

Aquatic macroinvertebrate assemblages in wetlands of Northeastern China

Hydrobiologia - Lake Malaŵi cichlids have evolved rapidly, extensively, and in some cases iteratively to fill an array of ecological niches; however, neither species richness nor trophic...     

YAP regulates periodontal ligament cell differentiation into myofibroblast interacted with RhoA/ROCK pathway

During orthodontic tooth movement (OTM), periodontal ligament cells (PDLCs) receive the mechanical stimuli and transform it into myofibroblasts (Mfbs). Indeed, previous studies have demonstrated that mechanical stimuli can promote the expression of Mfb marker α-smooth muscle actin (α-SMA) in PDLCs. Transforming growth factor β1 (TGF-β1), as the target gene of yes-associated protein (YAP), has been proven to be involved in this process. Here, we sought to assess the role of YAP in Mfbs differentiation from PDLCs. The time-course expression of YAP and α-SMA was manifested in OTM model in vivo as well as under tensional stimuli in vitro. Inhibition of RhoA/Rho-associated kinase (ROCK) pathway using Y27632 significantly reduced tension-induced Mfb differentiation and YAP expression. Moreover, overexpression of YAP with lentiviral transfection in PDLCs rescued the repression effect of Mfb differentiation induced by Y27632. These data together suggest a crucial role of YAP in regulating tension-induced Mfb differentiation from PDLC interacted with RhoA/ROCK pathway.     

Models and Algorithms for Hub and Spoke Locations for Emergency Service Facilities in Response to Serious Emergency Incidents

This article examines the location-allocation of emergency service facilities as a research subject. The research presents the setup of the single allocation set covering location-allocation models for emergency service facilities under strong time constraints, in view of the shortage of hub & spoke network bypass. The article also presents an extension to the single allocation set covering location-allocation model (SASCP) and the SASCP model with bypass constraints (γ-SASCP) for emergency service facilities under large-scale emergency requirements. For the two models, an improved genetic algorithm was designed and the two models were respectively solved, with the effectiveness of the algorithm verified by a specific example. The impacts of change of parameters such as time discount rate, maximum time constraints, and bypass ratio on the model's results are compared and analyzed, based on solved results by the specific example.     

Prediction of the Mechanism of Action of Fusaricidin on Bacillus subtilis

Long-term use of antibiotics has engendered a large number of resistant pathogens, which pose a serious threat to human health. Here, we investigated the mechanism of fusaricidin antibacterial activity toward Bacillus subtilis and characterized the pathways responsible for drug resistance. We found that σ^w, an extracytoplasmic function sigma factor, plays an important role in the resistance to fusaricidins during the initial 5 minutes of drug addition. Approximately 18 genes were induced more than 3-fold, of which 66.7% are known to be regulated by σ^w. Over the following 3 h, fusaricidins induced 194 genes more than three-fold, and most were associated with classes of antibiotic-responsive stimulons. Moreover, the fusaricidin treatment increased the catabolism of fatty and amino acids but strongly repressed glucose decomposition and gluconeogenesis. In summary, our data provide insight into the mechanism of fusaricidin activity, on which we based our suggested strategies for the development of novel antibiotic agents.