Exploring the trends of adaptation and evolution of sclerites with regards to habitat depth in sea pens.

Octocorals possess sclerites, small elements comprised of calcium carbonate (CaCO3) that are important diagnostic characters in octocoral taxonomy. Among octocorals, sea pens comprise a unique order (Pennatulacea) that live in a wide range of depths. Habitat depth is considered to be important in the diversification of octocoral species, but a lack of information on sea pens has limited studies on their adaptation and evolution across depth. Here, we aimed to reveal trends of adaptation and evolution of sclerite shapes in sea pens with regards to habitat depth via phylogenetic analyses and ancestral reconstruction analyses. Colony form of sea pens is suggested to have undergone convergent evolution and the loss of axis has occurred independently across the evolution of sea pens. Divergences of sea pen taxa and of sclerite forms are suggested to depend on habitat depths. In addition, their sclerite forms may be related to evolutionary history of the sclerite and the surrounding chemical environment as well as water temperature. Three-flanged sclerites may possess the tolerance towards the environment of the deep sea, while plate sclerites are suggested to be adapted towards shallower waters, and have evolved independently multiple times. The common ancestor form of sea pens was predicted to be deep-sea and similar to family Pseudumbellulidae in form, possessing sclerites intermediate in form to those of alcyonaceans and modern sea pens such as spindles, rods with spines, and three-flanged sclerites with serrated edges sclerites, as well as having an axis and bilateral traits.

O-acetylesterase activity of Bifidobacterium bifidum sialidase facilities the liberation of sialic acid and encourages the proliferation of sialic acid scavenging Bifidobacterium breve.

Bifidobacterium bifidum possesses two extracellular sialidases (SiaBb1 and SiaBb2) that release free sialic acid from mucin sialoglycans, which can be utilized via cross-feeding by Bifidobacterium breve that, otherwise, is prevented from utilizing this nutrient source. Modification of sialic acids with O-acetyl esters is known to protect mucin glycans from degradation by bacterial sialidases. Compared to SiaBb2, SiaBb1 has an additional O-acetylesterase (Est) domain. We aimed to elucidate the role of the SiaBb1 Est domain from B. bifidum in sialic acid cross-feeding within Bifidobacterium. Pre-treatment of mucin secreted from bovine submaxillary glands (BSM) using His6 -tagged-Est and -SiaBb2 released a higher amount of sialic acid compared to the pre-treatment by His6 -SiaBb2. Growth of B. breve increased with an increase in nanE expression when supplemented with both His6 -Est- and His6 -SiaBb2-treated BSM. These results indicate that the esterase activity of the SiaBb1 Est domain enhances the efficiency of SiaBb2 to cleave sialic acid from mucin. This free sialic acid can be utilized by coexisting sialic acid scavenging B. breve via cross-feeding. Here, we provide the molecular mechanism underlying the unique sialoglycan degradation property of B. bifidum which is mediated by the complementary activities of SiaBb1 and SiaBb2 in the context of sialic acid cross-feeding.

Two new species of the genus Chironephthya (Octocorallia, Alcyonacea, Nidaliidae, Siphonogorgiinae) from the Gulf of Thailand.

Two new species of the genus Chironephthya, C. sirindhornae sp. nov. and C. cornigera sp. nov., are described based on three specimens collected from the Gulf of Thailand. Both species are well distinguished from the previously described species of the genus Chironephthya by their colonies consisting of multiple stems that stand upright from a common base, and by a significantly thinner canal wall without large spindles. As a result of phylogenetic analyses using COI, mtMutS, and 28S rDNA sequences of these two species, these three specimens constituted an independent small clade within a large mixed clade of Siphonogorgia and Chironephthya, with the two species slightly different from each other. The discrepancy in the morphology suggested the erection of a new genus to accommodate these species, however, as the subclade was included in a large mixed clade of Siphonogorgia and Chironephthya, we place these species within genus Chironephthya. Our results further highlight the continuing confusion between Siphonogorgia and Chironephthya, and demonstrate the need for taxonomic revision of these genera.

Molecular phylogeny and diversity of sea pens (Cnidaria: Octocorallia: Pennatulacea) with a focus on shallow water species of the northwestern Pacific Ocean.

The order Pennatulacea, commonly known as sea pens, are colony-forming benthos belonging within subclass Octocorallia (Anthozoa, Cnidaria). Sea pens are found worldwide from shallow to deep waters, and they are important components in sandy and muddy environments. Thus far, there has been only one molecular study focusing on the phylogenetic relationships within the order Pennatulacea, which mainly treated deep-sea species, and thus information on shallow water species is still lacking. On a regional scale, the diversity of sea pens in the northwestern Pacific, including Japan and Palau, has not been well investigated. In this research, we aimed to: (1) more accurately resolve the phylogenetic relationships of sea pens with the inclusion of shallow water species, and (2) obtain a better understanding of the diversity of sea pens in Japan and Palau. Specimens were collected by SCUBA and dredging from the Ryukyu Islands in southern Japan, and from mainland Japan and Palau, and identified to at least the genus level by their morphological traits. Construction of phylogenetic trees with concatenated sequences including the mitochondrial mutS-like protein DNA mismatch repair gene mtMutS and the NADH dehydrogenase subunit 2 ND2 region were performed. The p-distances of mtMutS were calculated for estimation of species number following McFadden et al. (2011). Molecular data for 12 families and 20 genera of sea pens were used in this study. This most comprehensive study including shallow water taxa provided us with more knowledge of phylogenetic relationships. The resulting phylogenetic trees showed a topology distinguished by four large clades (clades 1-4). Families Veretillidae and Echinoptilidae are shown as not the earliest-diverging taxa. Virgulariidae and Scleroptilidae are shown as polyphyletic groups, and our results reconfirm that families Pennatulidae, Kophobelemnidae and Umbellulidae are not monophyletic groups. Overall, we collected and examined an estimated 18 species from the Ryukyu Islands, 16 species from mainland Japan, and five species from Palau. Some of these specimens represented new records from Ryukyu Islands and Palau. Previous records of these sea pens did not exist likely due to a lack of diversity research in sandy and muddy areas. These results demonstrate that many sea pens discoveries likely remain in shallow waters of the Pacific.