Many cellular processes are associated with membrane remodeling. The BAR domain protein family plays a key role in the formation and detection of local membrane curvatures and in attracting other proteins, including the regulators of actin dynamics. Based on their structural and phylogenetic properties, BAR domains are divided into several groups which affect membrane in various ways and perform different functions in cells. However, recent studies have uncovered evidence of functional differences even within the same group. This review discusses the principles underlying the interactions of different groups of BAR domains, and their individual representatives ,with membranes.
The pollen morphology and ultrastructure of Cycas micholitzii, C. simplicipinna, Cycandra profusa, Ceratozamia mexicana, and Ginkgo biloba are studied. Pollen germination is also studied in C. mexicana and G. biloba. Although dehydrated pollen grains appear monosulcate, the study of hydrated pollen shows that the aperture occupies nearly half of the pollen surface and represents a pore rather than a sulcus. In the Ginkgoales, the inaperturate ectexine is characterized by a thick solid tectum, infratectum of columella-like elements or large granules, and distinct foot layer. On the contrary, in the Cycadales, the ectexine consists of a thin tectum, alveolar infratectum, and poorly discernable foot layer. Members of the Ginkgoales have a distinct distal aperture, which is constituted by an intine, endexine, and thin ectexine. In the modern Cycadales, an ectexine is well developed throughout the pollen perimeter; in the supposed aperture region the ectexine is not reduced in thickness, although it is characterized by a thinner tectum and thinner walls of infratectal alveoli. In Cycandra profusa, no unequivocal aperture region has been found. Thickened regions were observed in the intine of both the Cycadales and Ginkgoales.
Grass pollen is one of the major causes of allergy. Aerobiological monitoring is a necessary element of the complex of anti-allergic measures, but the similar pollen morphology of Poaceae species makes it challenging to discriminate species in airborne pollen mixes, which impairs the quality of aerobiological monitoring. One of the solutions to this problem is the metabarcoding approach employing DNA barcodes for taxonomical identification of species in a mix by high-throughput sequencing of the pollen DNA. A diverse set of 14 grass species of different genera were selected to create a local reference database of nuclear ITS1, ITS2, 5′-ETS, and plastome trnL-F DNA barcodes. Sequences for the database were Sanger sequenced from live field and herbarium specimens and collected from GenBank. New Poaceae-specific primers for 5′-ETS were designed and tested to obtain a 5′-ETS region less than 600 bp long, suitable for high-throughput sequencing. The DNA extraction method for single-species pollen samples and mixes was optimized to increase the yield for amplification and sequencing of pollen DNA. Barcode sequences were analyzed and compared by the barcoding gap and intra- and interspecific distances. Their capability to correctly identify grass pollen was tested on artificial pollen mixes of various complexity. Metabarcoding analysis of the artificial pollen mixes showed that nuclear DNA barcodes ITS1, ITS2, and 5′-ETS proved to be more efficient than the plastome barcode in both amplification from pollen DNA and identification of grass species. Although the metabarcoding results were qualitatively congruent with the actual composition of the pollen mixes in most cases, the quantitative results based on read-counts did not match the actual ratio of pollen grains in the mixes.