In the present study, a high percentage of Japanese anglerfish, Lophius litulon (Jordan, 1902), contained a microsporidian infection of the nervous tissues. Xenomas were removed and prepared for standard wax histology and transmission electron microscopy (TEM). DNA extractions were performed on parasite spores and used in PCR and sequencing reactions. Fresh spores measured 3.4 × 1.8 µm and were uniform in size with no dimorphism observed. TEM confirmed that only a single developmental cycle and a single spore form were present. Small subunit (SSU) rDNA sequences were >99.5% similar to those of Spraguea lophii (Doflein, 1898) and Glugea americanus (Takvorian et Cali, 1986) from the European and American Lophius spp. respectively. The microsporidian from the nervous tissue of L. litulon undoubtedly belongs in the genus Spraguea Sprague et Vávra, 1976 and the authors suggest a revision to the generic description of Spraguea to include monomorphic forms and the transfer of Glugea americanus to Spraguea americana comb. n. Since no major differences in ultrastructure or SSU rDNA sequence data exist between Spraguea americana and the microsporidian from the Japanese anglerfish, they evidently belong to the same species. This report of Spraguea americana is the first report of a Spraguea species from L. litulon and indeed from the Pacific water mass.
It is easily seen that the graphs of harmonic conjugate functions (the real and imaginary parts of a holomorphic function) have the same nonpositive Gaussian curvature. The converse to this statement is not as simple. Given two graphs with the same nonpositive Gaussian curvature, when can we conclude that the functions generating their graphs are harmonic? In this paper, we show that given a graph with radially symmetric nonpositive Gaussian curvature in a certain form, there are (up to) four families of harmonic functions whose graphs have this curvature. Moreover, the graphs obtained from these functions are not isometric in general.
The purpose of the work is to establish the correlation between the change of absolute rotation poles of major tectonic plates based on continuous GNSS stations data. The work investigates 2804 continuous GNSS stations located on Pacific, North American, Eurasian, African, Antarctic, Australian and South American plates during 2002-2021. The components of recent horizontal displacements of continuous GNSS stations have been determined and a map of their distribution pattern has been constructed. The absolute rotation pole in ITRF2014/IGS14 reference frame of the studied tectonic plates has been determined. The obtained values are in good agreement with modern plate models. The definition of average annual rotation poles has been developed and their analysis has been carried out to research the dynamics of their change in time. It has been established that the change in the average annual rotation poles of the North American, African and South American plates occurs synchronously, while their change is asynchronous to the Pacific plate. Simultaneous changes in the average annual rotation poles of Antarctic and African plates were have also been identified.