Efficient protoplast isolation from fungi using commercial enzymes

Several commercial polysaccharases have been compared for their ability to liberate protoplasts from fungi. These enzymes were found to contain side activities capable of hydrolysing fungal cell walls. Protoplasts have been commonly isolated from fungi using enzyme systems prepared by workers in their own laboratories. However, these procedures are time consuming and considerable variation may be found between different batches of enzyme. The present study shows that high yields of protoplasts can be prepared from a variety of fungi using relatively cheap commercial enzymes. The yields obtained were normally as good as or better than those previously produced.     

Mediation of pinocytosis in cultured arterial smooth muscle and endothelial cells by platelet-derived growth factor

Pinocytosis was measured in monkey aortic smooth muscle cells (SMC), bovine aortic endothelial cells, and Swiss 3T3 cells in culture as cellular uptake of [U-(14)C]sucrose and horseradish peroxidase (HRP) from the tissue culture medium. Monkey arterial SMC and Swiss 3T3 cells were maintained in a quiescent state of growth at low cells density in medium containing 5 percent monkey plasma-derived serum (PDS). Replacement of PDS with 5 percent monkey whole blood serum (WBS) from the same donor, or addition to PDS of partially purified platelet-derived growth factor(s) (PF), resulted in a marked stimulation of pinocytosis as well as of cellular proliferation. In SMC, enhancement of the rate of pinocytosis occurred 4-6 h after exposure to WBS or PF, and the rate was up to twofold higher than the rate in medium containing PDS. In contrast, [(3)H]thymidine uptake by SMC did not increase until 12-16 h after exposure to PF. In endothelial cells the presence of PF or WBS did not enhance either the rate of pinocytosis or the rate of proliferation over that in PDS. Thus, endothelial cells did not become quiescent at subconfluent densities in PDS but maintained rates of proliferation and pinocytosis that were equivalent to those in WBS. By autoradiography, the fraction of labeled nuclei in SMC cultures 24 h after change of medium increased from 0.061 +/- 0.004 in quiescent cultures to 0.313 +/- 0.028 after exposure to WBS or PF. In contrast, labeling indices of endothelial cells were similar for cultures grown in PDS, WBS, or PF at any single time point after change of medium. These findings suggest that the rate of pinocytosis maybe be coupled in some fashion to growth regulation, which may be mediated in part by specific growth factors, such as that derived from the thrombocyte.     

Talking rot ... and mildew on textiles

Nature has evolved some very elegant elementary mechanisms for re-cycling of organic substances in the environment. These processes are normally beneficial. This article describes why microorganisms may attack textiles during production and in use, causing financial losses, and what can be done to prevent this happening.     

Na(+) entry via store-operated channels modulates Ca(2+) signaling in arterial myocytes

In manynonexcitable cells, hormones and neurotransmitters activateNa⁺ influx and mobilizeCa²⁺ from intracellular stores.The stores are replenished by Ca²⁺influx via "store-operated"Ca²⁺ channels (SOC). The mainroutes of Na⁺ entry in these cellsare unresolved, and no role forNa⁺ in signaling has beenrecognized. We demonstrate that the SOC are a majorNa⁺ entry route in arterialmyocytes. Unloading of the Ca²⁺stores with cyclopiazonic acid (a sarcoplasmic reticulumCa²⁺ pump inhibitor) and caffeineinduces a large externalNa⁺-dependent rise in thecytosolic Na⁺ concentration. Onecomponent of this rise in cytosolicNa⁺ concentration is likely due toNa⁺/Ca²⁺exchange; it depends on elevation of cytosolicCa²⁺ and is insensitive to 10 mMMg²⁺ and 10 µMLa³⁺. Another component isinhibited by Mg²⁺ andLa³⁺, blockers of SOC; thiscomponent persists in cells preloaded with1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraaceticacid to buffer Ca²⁺ transients andpreventNa⁺/Ca²⁺exchange-mediated Na⁺ entry. ThisNa⁺ entry apparently is mediatedby SOC. The Na⁺ entry influencesNa⁺ pump activity andNa⁺/Ca²⁺exchange and has unexpectedly large effects on cell-wideCa²⁺ signaling. The SOC pathwaymay be a general mechanism by which Na⁺ participates in signaling inmany types of cells.

     

Control of stem cell fate by engineering their micro and nanoenvironment

Stem cells are capable of long-term self-renewal and differentiation into specialised cell types, making them an ideal candidate for a cell source for regenerative medicine. The control of stem cell fate has become a major area of interest in the field of regenerative medicine and therapeutic intervention. Conventional methods of chemically inducing stem cells into specific lineages is being challenged by the advances in biomaterial technology, with evidence highlighting that material properties are capable of driving stem cell fate. Materials are being designed to mimic the clues stem cells receive in their in vivo stem cell niche including topographical and chemical instructions. Nanotopographical clues that mimic the extracellular matrix(ECM) in vivo have shown to regulate stem cell differentiation. The delivery of ECM components on biomaterials in the form of short peptides sequences has also proved successful in directing stem cell lineage. Growth factors responsible for controlling stem cell fate in vivo have also been delivered via biomaterials to provide clues to determine stem cell differentiation. An alternative approach to guide stem cells fate is to provide genetic clues including delivering DNA plasmids and small interfering RNAs via scaffolds. This review, aims to provide an overview of the topographical, chemical and molecular clues that biomaterials can provide to guide stem cell fate. The promising features and challenges of such approaches will be highlighted, to provide directions for future advancements in this exciting area of stem cell translation for regenerative medicine.     

Response of photosynthetic apparatus to moderate high temperature in contrasting wheat cultivars at different oxygen concentrations

The photosynthetic responses to moderately high temperatures (38 degrees C, imposed at 21% or 2% O(2) in air and 1500 mumol m(-2) s(-1)) were compared in wheat (Triticum aestivum L.) cultivars grown in northern regions of Ukraine and expected to be relatively sensitive to high temperatures ('North' cultivars) and in cultivars grown in southern regions and expected to be relatively heat-tolerant ('South' cultivars). Heating intact leaves in 21% O(2) for 1 h decreased CO(2) assimilation by c. 63% in 'North' cultivars and only c. 32% in 'South' cultivars, with a decrease in PSII activity being observed in only one of the 'North' cultivars. Carboxylation efficiency was decreased by about 2.7-fold in 'North' cultivars with no significant effect in 'South' cultivars. The maximum rates of carboxylation by Rubisco in vivo, V(cmax), estimated from Farquhar's model, increased more than 2-fold in 'South' cultivars and remained unchanged in 'North' cultivars while the maximum rate of RuBP regeneration, J(max), decreased by 53% and 21% in 'North' and 'South' cultivars, respectively. Where the heat treatment was imposed in 2% O(2) this increased (as compared with treatment at 21% O(2)) the inhibitory effect on CO(2) assimilation in tolerant cultivars, but decreased it in sensitive ones. The results suggested that differences in tolerance of moderately high temperatures in wheat relate to the stability of the Rubisco function and to RuBP regeneration activity rather than to the effects on PSII activity or stomatal control.     

Genetic covariance between indices of body condition and immunocompetence in a passerine bird

Background  

Condition-dependence is a ubiquitous feature of animal life histories and has important implications for both natural and sexual selection. Mate choice, for instance, is typically based on condition-dependent signals. Theory predicts that one reason why condition-dependent signals may be special is that they allow females to scan for genes that confer high parasite resistance. Such explanations require a genetic link between immunocompetence and body condition, but existing evidence is limited to phenotypic associations. It remains unknown, therefore, whether females selecting males with good body condition simply obtain a healthy mate, or if they acquire genes for their offspring that confer high immunocompetence.