Notes on Gracilaria (Gracilariales, Rhodophyta) from Tosa Bay and adjacent waters I : Gracilaria chorda, Gracilaria gigas and Gracilaria incurvata.

Three species of Gracilaria (Gracilariales, Rhodophyta): Gracilaria chorda Holmes, Gracilaria gigas Harvey, and Gracilaria incurvata Okamura growing at Tosa Bay and adjacent waters (Kochi Prefecture, Japan) were reported and their characteristic features described. G. chorda as well as G. gigas was founded at Uranouchi Inlet, Tosa City (central Tosa Bay). The morphology of G. chorda varied greatly among the different habitats and seasons. Some young plants collected from April to May had long chord-like appearances without branchlets, while the older plants collected from June to July showed numerous filiform branchlets. However, reproductive organs of these plants agree well with the descriptions by Ohmi (1958) and Yamamoto (1978). Although the old fronds of G. gigas were similar to in shape to the aged plant of G. chorda in terms of vegetative appearance, it differed from the latter in regard to its spermatangial features and the presence of traversing filaments in the cystocarp. G. incurvata was found at Uranouchi Inlet and was also found at Kashiwajima, Ohtsuki town, and at Oh-hama, Tosashimizu City (western Tosa Bay). This species closely resembled G. textorii in regard to its flattened appearance, while the reproductive characteristics of this species also resembled those of the latter. However, a curved or twisted shape was shown only in G. incurvata

Morphological and molecular phylogenetic studies of a red alga, Halymenia durvillei, (Halymeniaceae, Halymeniales) from Indo-Pacific

Morphological and molecular phylogenetic studies were made on recently collected Halymenia plants widely from Japan, the Philippines, Indonesia, Malaysia and Thailand. Although the external morphology (branching pattern, blade width, or degree of dentation) was very variable, no special differences were found in their vegetative and reproductive structures. The features are close to Halymenia durvillei. Our rbcL gene sequence analysis has shown that the branched Halymenia plants are all included in a distinct, monophyletic clade, separate from those including the foliose plants. The branched plants studied here are, therefore, concluded to belong in a single species, Halymenia durvillei, irrespective of their great external variations. As Halymenia microcarpa clearly fall within the range of external variations of H. durvillei, it was concluded to be synonymous with H. durvillei. The taxonomic interrelationship among the four varieties (var. formosa, var. ceylanica, var. denudata and var. edentata) remained unresolved, although apprently encompassed within the morphological range of H. durvillei

The phenology of epiphytic diatoms and epifauna observed on Zostera marina of Arikawa Bay, Nagasaki Prefecture, Japan

We present a descriptive account of the dynamics of epiphytic diatoms, epifauna, and the leaf surface area of Zostera marina in a shallow water ecosystem. We hypothesized that the growth stage of the host macrophyte (i.e., leaf surface area) influenced the presence of epiflora and epifauna, as well as that the leaf surface area and epifaunal population density affected the cell density and species composition of epiphytic diatoms. To evaluate this hypothesis, we quantified the leaf surface area of a host macrophyte (Zostera marina), the presence of epifauna, and the community of epiphytic diatoms that could be observed on the leaves of Z. marina during the period from May 2017 to December 2018. We conducted a descriptive analysis of the time-series observations of leaf surface area, epiphytic diatom density, and epifauna population density. Epiphytic diatom density was low and epifauna density was high during the growing season of Z. marina. Epiphytic diatom density was high and epifauna density was low during the maturation and senescence periods of Z. marina. Our analysis shows that epifauna densities lagged epiflora densities by at least four months, and that epiflora densities lagged leaf area by four months. Therefore, we hypothesized that herbivorous gastropods and amphipods could alter species composition via their preference of food items (active choice) or by ingesting more of the species that were structurally more available (passive preference)

Preliminary report on the molecular phylogeny of the Laurencia complex (Rhodomelaceae)

A molecular phylogenetic analysis of three closely related red algal genera, Laurencia, Chondrophycus and Osmundea (Rhodomelaceae) that are often called the Laurencia complex or Laurencia sensu lato, mainly of the north-western Pacific species, was carried out based on rbcL gene sequences. The sequence data downloaded from GenBank were also included in our analysis. The monophyly of the clade of Osmundea species was supported by high bootstrap value. All examined species of Laurencia sensu stricto with typical features (four periaxial cells per vegetative axial segment, longitudinally oriented secondary pit-connections between contiguous superficial cortical cells, corps en cerise within superficial cortical and trichoblast cells) also constituted a monophyletic clade with high bootstrap value. On the other hand, Chondrophycus species were divided into two separated clades with relatively high bootstrap values respectively. Furthermore, L. flexilis, which has four periaxial cells per vegetative axial segment but lacks secondary pit-connections between contiguous superficial cortical cells, constituted an independent monophyletic clade with high bootstrap value. These results suggest that only two groups, Osmundea and the typical Laurencia, are monophyletic and Chondrophycus is polyphyletic within the Laurencia complex. The phylogenetic position of L. flexilis, an intermediate species between the typical Laurencia and Chondrophycus, must be clarified to determine the key features to distinguish Chondrophycus and Laurencia sensu stricto. Further investigations based on the other genes are expected

Novel method for immunofluorescence staining of mammalian eggs using non-contact alternating-current electric-field mixing of microdroplets

Recently, a new technique was developed for non-catalytically mixing microdroplets. In this method, an alternating-current (AC) electric field is used to promote the antigen-antibody reaction within the microdroplet. Previously, this technique has only been applied to histological examinations of flat structures, such as surgical specimens. In this study, we applied this technique for the first time to immunofluorescence staining of three-dimensional structures, specifically, mammalian eggs. We diluted an antibody against microtubules from 1:1,000 to 1:16,000, and compared the chromatic degree and extent of fading across dilutions. In addition, we varied the frequency of AC electricfield mixing from 5 Hz to 46 Hz and evaluated the effect on microtubule staining. Microtubules were more strongly stained after AC electric-field mixing for only 5 minutes, even when the concentration of primary antibody was 10 times lower than in conventional methods. AC electric-field mixing also alleviated microtubule fading. At all frequencies tested, AC electric-field mixing resulted in stronger microtubule staining than in controls. There was no clear difference in a microtubule staining between frequencies. These results suggest that the novel method could reduce antibody consumption and shorten immunofluorescence staining time

Structural aging of human neurons is the opposite of the changes in schizophrenia

Human mentality develops with age and is altered in psychiatric disorders, though their underlying mechanism is unknown. In this study, we analyzed nanometer-scale three-dimensional structures of brain tissues of the anterior cingulate cortex from eight schizophrenia and eight control cases. The distribution profiles of neurite curvature of the control cases showed a trend depending on their age, resulting in an age-correlated decrease in the standard deviation of neurite curvature (Pearson's r = -0.80, p = 0.018). In contrast to the control cases, the schizophrenia cases deviate upward from this correlation, exhibiting a 60% higher neurite curvature compared with the controls (p = 7.8 x 10^(-4)). The neurite curvature also showed a correlation with a hallucination score (Pearson's r = 0.80, p = 1.8 x 10^(-4)), indicating that neurite structure is relevant to brain function. We suggest that neurite curvature plays a pivotal role in brain aging and can be used as a hallmark to exploit a novel treatment of schizophrenia. This nano-CT paper is the result of our decade-long analysis and is unprecedented in terms of number of cases.Comment: 24 pages, 5 figures. arXiv admin note: text overlap with arXiv:2007.0021

The RRM domain of poly(A)-specific ribonuclease has a noncanonical binding site for mRNA cap analog recognition

The degradation of the poly(A) tail is crucial for posttranscriptional gene regulation and for quality control of mRNA. Poly(A)-specific ribonuclease (PARN) is one of the major mammalian 3′ specific exo-ribonucleases involved in the degradation of the mRNA poly(A) tail, and it is also involved in the regulation of translation in early embryonic development. The interaction between PARN and the m7GpppG cap of mRNA plays a key role in stimulating the rate of deadenylation. Here we report the solution structures of the cap-binding domain of mouse PARN with and without the m7GpppG cap analog. The structure of the cap-binding domain adopts the RNA recognition motif (RRM) with a characteristic α-helical extension at its C-terminus, which covers the β-sheet surface (hereafter referred to as PARN RRM). In the complex structure of PARN RRM with the cap analog, the base of the N7-methyl guanosine (m7G) of the cap analog stacks with the solvent-exposed aromatic side chain of the distinctive tryptophan residue 468, located at the C-terminal end of the second β-strand. These unique structural features in PARN RRM reveal a novel cap-binding mode, which is distinct from the nucleotide recognition mode of the canonical RRM domains