Redescription of Nothobomolochus triceros (Bassett-Smith, 1898) (Copepoda, Cyclopoida, Bomolochidae), with descriptions of the male and copepodids V-II of the species

Nothobomolochus triceros (Bassett-Smith, 1898), based on specimens recovered from the original host Pampus argenteus (Euphrasen, 1788) in Japan, are redescribed, and the male, both sexes of copepodids V and IV, and sex undetermined copepodids III and II of the species are described for the first time. The maxilliped is sexually dimorphic only in the adult in Bomolochidae, on the other hand, the rostral plate, antennule, and legs 1, 4, and 5 are sexually dimorphic in Nothobomolochus throughout the adult and copepodids V-IV. Sex is as yet undetermined in copepodids III and II in the genus.

Redescription of Triceracolax pagri Izawa, 2021 (Copepoda, Cyclopoida, Bomolochidae), with descriptions of copepodids IV and III of the species

Triceracolax pagri Izawa, 2021 is redescribed on the basis of specimens of both sexes recovered from the bucco-branchial cavity of the original host, Pagrus major (Temminck & Schlegel, 1843). Both sexes of copepodid IV and the male copepodid III, collected together with the adults, are described for the first time, and sexually dimorphic features in late copepodid stages are discussed.

Redescription of Naricolax sphyraenae Izawa, 2020 (Copepoda, Cyclopoida, Bomolochidae), with a correctional description of copepodid IV of the species

As in the original description of Naricolax sphyraenae Izawa, 2020, copepodid IV female of the species was described based on a wrong judgement of the sex, the species is redescribed and both sexes of copepodid IV of the species are correctively described, while additionally copepodid V male of the species is described for the first time, based on specimens newly collected from the original host, Sphyraena pinguis Günther, 1874 (Pisces, Sphyraenidae) from Japan.

Description of Megacolax gen. nov. and redescription of Megacolax insolitus (Ho & Lin, 2003) (Copepoda, Cyclopoida, Bomolochidae) parasitic in the nasal cavity of the silver pomfret Pampus argenteus (Euphrasen, 1788) (Pisces, Stromateidae)

Megacolax gen. nov. (Copepoda, Cyclopoida, Bomolochidae) is established to accommodate Naricolax insolitus Ho & Lin, 2003, and next Megacolax insolitus (Ho & Lin, 2003) emended is redescribed based on specimens of both sexes recovered from the nasal cavity of the original host, Pampus argenteus (Euphrasen, 1788) (Pisces, Stromateidae) in Japan. The male is described for the first time for the species.

Taxonomy and phylogeny of Aphanomycopsis bacillariacearum, a holocarpic oomycete parasitoid of the freshwater diatom genus Pinnularia

Investigations into simple holocarpic oomycetes are challenging, because of the obligate biotrophic nature of many lineages and the periodic presence in their hosts. Thus, despite recent efforts, still, the majority of species described remains to be investigated for their phylogenetic relationships. One of these species is Aphanomycopsis bacillariacearum, the type species of the genus Aphanomycopsis. Species of Aphanomycopsis are endobiotic holocarpic parasites of diverse hosts (e.g., diatoms, desmids, dinoflagellates). All species classified in this genus were assigned to it based on the presence of branching hyphae and the formation of two generations of zoospores, of which the first one is not motile. Originally, Aphanomycopsis with its type species, A. bacillariacearum, had been classified in the Saprolegniaceae. However, the genus has undergone multiple taxonomic reassignments (to Ectrogellaceae, Lagenidiaceae, and Leptolegniellaceae) in the past. To settle the taxonomy and investigate the phylogenetic placement of Aphanomycopsis, efforts were undertaken to isolate A. bacillariacearum from its original host, Pinnularia viridis and infer its phylogenetic placement based on nrSSU (18S) sequences. By targeted isolation, the diatom parasitoid was rediscovered from Heiðarvatn lake, Höskuldsstaðir, Iceland. Phylogenetic reconstruction shows that A. bacillariacearum from Pinnularia viridis is embedded within the Saprolegniales, and largely unrelated to both diatom-infecting oomycetes in the Leptomitales (Ectrogella, Lagenisma) and those placed within the early-diverging lineages (Miracula, Diatomophthora) of the Oomycota.

MushPEC: Correcting Post-entrapment Processes Affecting Melt Inclusions Hosted in Olivine Antecrysts

Olivine-hosted melt inclusions (MIs) are widely used as a tool to study the early stages of magmatic evolution. There are a series of processes that affect MI compositions after trapping, including post-entrapment crystallization (PEC) of the host mineral at the MI boundaries, exsolution of volatile phases into a “shrinkage bubble” and diffusive exchange between a MI and its host. Classical correction schemes applied to olivine-hosted MIs include PEC correction through addition of olivine back to the melt until it reaches equilibrium with the host composition and “Fe-loss” correction due to Fe-Mg diffusive exchange. These corrections rely on the assumption that the original host composition is preserved. However, for many volcanic samples the crystal cargo is thought to be antecrystic, and the olivine composition may thus have been completely re-equilibrated during long crystal storage times. Here, we develop a novel MI correction scheme that is applicable when the original host crystal composition has not been preserved and the initial MI composition variability can be represented by simple fractional crystallization (FC). The new scheme allows correction of MI compositions in antecrystic hosts with long and varied temperature histories. The correction fits a set of MI compositions to modelled liquid lines of descent generated by FC. A MATLAB® script (called MushPEC) iterates FC simulations using the rhyolite-MELTS algorithm. In addition to obtaining the corrected MI compositions, the application of this methodology provides estimations of magmatic conditions during MI entrapment. A set of MIs hosted in olivine crystals of homogeneous composition (Fo77–78) from a basaltic tephra of Akita-Komagatake volcano was used to test the methodology. The tephra sample shows evidence of re-equilibration of the MIs to a narrow Mg# range equivalent to the carrier melt composition. The correction shows that olivine hosts were stored in the upper crust (c. 125 – 150 MPa) at undersaturated H2O contents of c. 1 – 2 wt% H2O).

Population genetics and host specificity of Varroa destructor mites infesting eastern and western honeybees

In a globalized world, parasites are often brought in contact with new potential hosts. When parasites successfully shift host, severe diseases can emerge at a large cost to society. However, the evolutionary processes leading to successful shifts are rarely understood, hindering risk assessment, prevention, or mitigation of their effects. Here, we screened populations of Varroa destructor, an ectoparasitic mite of the honeybee genus Apis, to investigate their genetic structure and reproductive potential on new and original hosts. From the patterns identified, we deduce the factors that influenced the macro- and microevolutionary processes that led to the structure observed. Among the mite variants identified, we found two genetically similar populations that differed in their reproductive abilities and thus in their host specificity. These lineages could interbreed, which represents a threat due to the possible increased virulence of the parasite on its original host. However, interbreeding was unidirectional from the host-shifted to the nonshifted native mites and could thus lead to speciation of the former. The results improve our understanding of the processes affecting the population structure and evolution of this economically important mite genus and suggest that introgression between shifted and nonshifted lineages may endanger the original host.

Watermark-based Copyright Protection Using Invariant Features for Remote Sensing Images

<p>With the development of remote sensing technology, the copyright protection of remote sensing images has become an urgent problem to be solved. In this paper, a blind watermarking scheme based on invariant features is applied. In the embedding process, the stable image features are firstly extracted from the original host using block DCT, and the embedding positions are constructed adaptively according to feature processing theory. Then, the watermark is embedded into the low-frequency coefficients by modifying the DC coefficients. For watermark extraction, according to the invariant image features in each region, the watermark location and the watermark information can be extracted without the original host. Experimental results show that the proposed watermarking is not only invisible and robust against common image processing, such as noise addition, image filtering, and JPEG compression, but also robust against cropping attack.</p>

COVID-19 Evolves in Human Hosts

Today, we are all threatened by an unprecedented pandemic: COVID-19. How different is it from other coronaviruses? Will it be attenuated or become more virulent? Which animals may be its original host? In this study, we analyzed 377 publicly available complete genome sequences for the COVID-19 virus, the previously known flu-causing coronaviruses (HCov-229E, HCov-OC43, HCov-NL63 and HCov-HKU1) and the lethal, pathogenic P3/P4 viruses, SARS, MERS, Victoria, Lassa, Yamagata, Ebola, and Dengue. We found strong similarities between the current circulating COVID-19 and SARS and MERS, as well as COVID-19 in rhinolophines and pangolins. On the contrary, COVID-19 shares little similarity with the flu-causing coronaviruses and the other P3/P4 viruses. Strikingly, we observed divergence of COVID-19 strains isolated from human hosts has steadily increased from December 2019 to March 2020, suggesting COVID-19 is actively evolving in human hosts. From all existing human COVID-19 genome sequences, we calculated the first common model that represents the shared sequences of the human COVID-19 strains, which provides important information for vaccine and antibody development. Geographic and time-course analysis of the evolutionary trees of the human COVID-19 reveals possibly heterogeneous evolutional paths among strains from 21 countries. This finding has important implications to the management of COVID-19 and the development of vaccines.

Steganography Genetic Algorithm Hyperparameter Tuning through Response Surface Methodology

Steganography consists of hidding bits of an information source into a host source. In image processing, a common way of doing the hiding process is to break each byte from the message information and embbed into the message bytes in a way that the differences among the original host and the embedded one is minimized. A genetic algorithm can be used to find the proper combination of bits in order to minimize such differences, but some hyperparameters need to be optimized in order to get an optimized performance. This work investigates the application of Response Surface Methodology in order to find the best hyperparameters of a genetic algorithm applied to image steganography.