Rapid expansion of the invasive-like red macroalga,Chondria tumulosa (Rhodophyta), on the coral reefs of the Papahānaumokuākea Marine National Monument

A cryptogenic, invasive-like red macroalga, Chondria tumulosa, was first observed in 2016 forming thick mats on the forereef of Manawai Atoll within Papahānaumokuākea Marine National Monument. Subsequent expeditions revealed an increased abundance of this alga. In 2021, unattached C. tumulosa was observed forming a network of dark, meandering accumulations throughout the atoll's inner lagoon. High-resolution satellite imagery revealed that these accumulations became visible in 2015 (length: ~0.74 km; area: ~0.88 km²) and increased 56-fold in length and 115-fold in area by 2021 (length: 41.32 km; area: 101.34 km²). An exponential expansion rate of ~16.02 km · y⁻¹ (length), ~44.75 km² · y⁻¹ (area). This study presents the comprehensive temporal and spatial expansion of C. tumulosa accumulations for Manawai Atoll since its discovery, providing ecologist and resource managers with a proxy to gauge the overall abundance trend of this invasive-like alga.     

Group 12 metal complexes with inner-salt, bis(N,N-disubstituted amino)carbeniumdithiocarboxylate. Asymmetric stretching vibration of thiocarboxylate and reduction potential as probes for the coordination mode

A series of Group 12 metal complexes with bis(N,N-disubstituted amino)carbeniumdithiocarboxylates (RL) have prepared by the reaction of metal perchlorate with RL in EtOH or CH₂Cl_2, and characterized by the X-ray structural analysis, IR spectrum, and electrochemical measurements. The composition of metal and RL and the coordination mode, such as monodentate, chelate, and bridging or capping, depend on both the central metal ion and the substituent on the diaminocarbenium moiety. The useful criteria for the coordination mode are found to be the wavenumber of the -CS₂ asymmetric stretching vibration in the solid state, and the ligand-based reduction potential in solution.     

Developmental expression of otoconin-22 in the bullfrog endolymphatic sac and inner ear.

In amphibians, calcium carbonate crystals are present in the endolymphatic sac and the inner ear. The formation of these crystals is considered to be facilitated by a protein called otoconin-22. We examined the spatial and temporal expression of otoconin-22 during the development of the bullfrog (Rana catesbeiana) using RT-PCR, in situ hybridization (ISH), and immunofluorescence techniques. By RT-PCR, otoconin-22 mRNA was first detected in embryos at Shumway stage 20, and this expression pattern continues in late stages. The first otoconin-22 mRNA-positive reaction was detected in stage 22 embryos in the placode of the endolymphatic sac. Otoconin-22 protein was observed in the epithelial cells of the endolymphatic sac at stage 24. On the other hand, a whole-mount ISH technique showed the first expression of otoconin-22 mRNA in the inner ear, in addition to the endolymphatic sac, at the mid-phase of Shumway stage 25. We discuss the role of otoconin-22 in the formation of calcium carbonate crystals in the endolymphatic sac and inner ear.     

NUB1-mediated targeting of the ubiquitin precursor UbC1 for its C-terminal hydrolysis.

NEDD8 is a ubiquitin-like protein that controls vital biological events through its conjugation to target proteins. Previously, we identified a negative regulator of the NEDD8 conjugation system, NEDD8 ultimate buster-1 (NUB1), that recruits NEDD8 and its conjugates to the proteasome for degradation. Recently, we performed yeast two-hybrid screening with NUB1 as bait and isolated a ubiquitin precursor UbC1 that is composed of nine tandem repeats of a ubiquitin unit through alpha-peptide bonds. Interestingly, NUB1 interacted with UbC1 through its UBA domain. Further study revealed that the UBA domain interacted with alpha-peptide bond-linked polyubiquitin, but not with isopeptide bond-linked polyubiquitin, indicating that the UBA domain of NUB1 is a specific acceptor for the linear ubiquitin precursor. A functional study revealed that an unidentified protein that was immunoprecipitated with NUB1 served as a ubiquitin C-terminal hydrolase for UbC1. Thus, NUB1 seems to form a protein complex with the unidentified ubiquitin C-terminal hydrolase and recruit UbC1 to this complex. This might allow the ubiquitin C-terminal hydrolase to hydrolyze UbC1, in order to generate ubiquitin monomers. Northern blot analysis showed that the mRNAs of both NUB1 and UbC1 were enriched in the testis. Furthermore, in situ hybridization showed that both mRNAs were strongly expressed in seminiferous tubules of the testis. These results may imply that the UbC1 hydrolysis mediated by NUB1 is involved in cellular functions in the seminiferous tubules such as spermatogenesis.