The detection of chemotaxis-related changes in the swimming behavior of mammalian spermatozoa in a spatial chemoattractant gradient has hitherto been an intractable problem. The difficulty is that the fraction of responsive cells in the sperm population is very small and that the large majority of the cells, though non-responsive, are motile too. Assessment of the chemotactic effects in a spatial gradient is also very sensitive to the quality of sperm tracking. To overcome these difficulties we propose a new approach, based on the analysis of the distribution of instantaneous directionality angles made by spermatozoa in a spatial gradient versus a no-gradient control. Although the use of this parameter does not allow identification of individual responding cells, it is a reliable measure of directionality, independent of errors in cell tracking caused by cell collisions, track crossings, and track splitting. The analysis identifies bias in the swimming direction of a population relative to the gradient direction. It involves statistical chi2 tests of the very large sample of measured angles, where the critical chi2 values are adjusted to the sample size by the bootstrapping procedure. The combination of the newly measured parameter and the special analysis provides a highly sensitive method for the detection of a chemotactic response, even a very small one.
Both rigid plastics and soft hydrogels find ample applications in engineering and medicine but bear their own disadvantages that limit their broader applications. Bonding these mechanically dissimilar materials may resolve these limitations, preserve their advantages, and offer new opportunities as biointerfaces. Here, a robust adhesion strategy is proposed to integrate highly entangled tough hydrogels and diverse plastics with high interfacial adhesion energy and strength.
Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China; Laoshan Laboratory, Qingdao, 266237, China.
Coastal bays link terrestrial and oceanic carbon reservoirs and play important roles in marine carbon cycles. Particulate organic carbon (POC) produced by phytoplankton is a major autochthonous carbon source in coastal bays. Previous studies on the fate of POC produced by phytoplankton mainly focused on the relationship between phytoplankton and zooplankton in classic food webs, while our knowledge on the roles of bacterioplankton is still limited, particularly in bays under highly intensive aquaculture activities.
Key Laboratory of Low-carbon Green Agriculture in Northwestern China, Ministry of Agriculture and Rural Affairs, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China. Electronic address:
Plastic films mulching, a management strategy designed to boost agricultural productivity, significantly impacts soil fertility and the turnover of soil organic carbon (SOC). Aggregates in the soil play a crucial role in this SOC cycling. Yet, the effect of mulching on the changes in organic carbon components and the mineralization at the aggregate scale is still not well understood.
The mutant selection window (MSW) is a range of antimicrobial concentrations, where some bacteria are killed, while others survive. Within this interval resistance may develop. Antimicrobial peptides (AMPs) are a promising class of antimicrobials that generally act by perturbing the integrity of bacterial membranes.
When processing lucuma (), waste such as shells and seeds is generated, which is a source of bioactive compounds. Recently, lucuma seed (LS), especially its oily fraction, has been studied for containing phytosterols and tocopherols, powerful antioxidants with health benefits. This study proposes lucuma seed oil (LSO) extraction using supercritical fluid (SCF) to improve the quality of the extract and minimize the environmental impact.
