Three new species of the family Aoridae collected from Sagami Bay, central Japan (Crustacea: Amphipoda).

Three new species of the amphipod family Aoridae Stebbing, 1899 were collected from the bottom of a 40400 m depth in Sagami Bay, central Japan. Aora biarticulata sp. nov. is characterized by the accessory flagellum with 2 articles, the weakly setose male gnathopod 1 and the male gnathopod 2 with setose carpus and propodus. Aoroides sagamiensis sp. nov. has a distinctive male gnathopod 1 with poorly setose basis and heavily setose merus. Grandidierella gracilis sp. nov. has stridulating ridges on the carpus of the male gnathopod 1. This new species can be distinguished from its related congeners by the teeth arrangement on the male gnathopod 1 carpus, the poorly setose antennae, the sparsely setose posterior margins of the pereopods 6, 7 bases, and the ordinary form of the male gnathopod 2.

Metarhachotropis parva, a new genus and species of Eusiridae (Crustacea: Amphipoda) from Sagami Bay, central Japan.

The monotypic genus Metarhachotropis (Crustacea: Amphipoda: Eusiridae) is erected with M. parva sp. nov. from Sagami Bay, central Japan, as its type species. This new genus is characterized by the massive head with large rostrum, the very short coxae and the strongly produced coxa 1. Metarhachotropis resembles Eusirella Chevreux, 1908 and Rhachotropis Smith, 1883; however, it can be distinguished from Eusirella by the ordinary length of the maxilla 1 palp, and from Rhachotropis by the smooth body.

Five species of the family Odiidae (Crustacea: Amphipoda) collected from Japan, with descriptions of a new genus and four new species.

Five species of the family Odiidae (Amphipoda), including four new species, are recorded from Japan: Metodius cyanomaculatus sp. nov.; M. leucomaculatus sp. nov.; Postodius albifacies sp. nov.; P. sanguineus sp. nov.; and Antarctodius japonicus Ariyama, 2011. Morphological characters and coloration of these species are described in detail. Metodius gen. nov. is established for the two new species and is characterized by the very short and bare palp of the maxilla 1 and the large gnathopod 2 propodus. Keys to the odiid genera and the Postodius species in the world are provided. The genera can be distinguished from one another by the shapes of maxilla 1, maxilliped, pereopod 7, and telson. The Postodius species differs in the shapes of gnathopod 2, and pereopods 3, 7. Female of A. japonicus is firstly recorded. In this species, the presence of an accessory flagellum and a gill on the coxa 7 is confirmed.

Blockade of the interaction between BMP9 and endoglin on erythroid progenitors promotes erythropoiesis in mice.

Bone morphogenetic protein-9 (BMP9), a member of the transforming growth factor ß (TGFß) superfamily, plays important roles in the development and maintenance of various cell lineages via complexes of type I and type II TGFß receptors. Endoglin is a coreceptor for several TGFß family members, including BMP9, which is highly expressed in a particular stage of differentiation in erythroid cells as well as in endothelial cells. Although the importance of the interaction between BMP9 and endoglin for endothelial development has been reported, the contribution of BMP9 to endoglin-expressing erythroid cells remains to be clarified. To address this point, we prepared an anti-BMP9 antibody that blocks the BMP9-endoglin interaction. Of note, challenge with the antibody promotes erythropoiesis in wild-type mice but not in a mouse model of renal anemia in which erythropoietin (EPO) production in the kidneys is genetically ablated. While endoglin-positive erythroid progenitors are mainly maintained as progenitors when bone marrow-derived lineage-negative and cKit-positive cells are cultured in the presence of EPO and stem cell factor, the erythroid-biased accumulation of progenitors is impeded by the presence of BMP9. Our findings uncover an unrecognized role for BMP9 in attenuating erythroid differentiation via its interaction with endoglin on erythroid progenitors.

The complete mitochondrial genome of the estuarine amphipod Grandidierella osakaensis (Crustacea: Amphipoda).

The complete mitochondrial genome sequence of an estuarine amphipod Grandidierella osakaensis was determined. The mitochondrial genome was 14,658 bp in length with 37 mitochondrial genes (13 protein-coding genes [PCGs], 2 ribosomal RNAs [rRNAs], and 22 transfer RNAs [tRNAs]). The order of PCGs of G. osakaensis was identical to those of other two Grandidierella species. A maximum likelihood-based phylogenetic analysis showed that G. osakaensis formed a monophyletic clade with the other two Grandidierella species within the infraorder Corophiida. The mitochondrial genome sequence obtained in this study provides useful information for further phylogenetic and ecological studies.

Species of the Maera-clade collected from Japan. Part 4: addenda to genera Maera Leach, 1814 and Quadrimaera Krapp-Schickel Ruffo, 2000, with revised keys to Japanese species of the clade (Crustacea: Amphipoda: Maeridae).

Two new species of Maera Leach, 1814 and Quadrimaera Krapp-Schickel Ruffo, 2000 included in the Maera-clade are described from Japan. Maera denticoxa sp. nov. was collected from Iwate and Hokkaido Prefectures and can be distinguished from its congeners by the small notches on the posteroventral margins of coxae 1-6. Quadrimaera angulata sp. nov. from north of Tanegashima Island in Kagoshima Prefecture is characterized by the distal tooth on the mandibular palp article 1, the rounded palm of the female gnathopod 2, and the angular posterodistal margin of the pereopod 7 basis. Keys to Japanese species of the Maera-clade are provided. In total, seventeen species included in the clade occur in Japan.

Six species of Grandidierella collected from the Ryukyu Archipelago in Japan, with descriptions of four new species (Crustacea: Amphipoda: Aoridae).

Six species of the amphipod genus Grandidierella Coutière, 1904 were collected from coastal areas of the Ryukyu Archipelago in Japan. Four species are new to science and the other two are new to Japan. Grandidierella contigua sp. nov. has a characteristic male gnathopod 1 with three teeth on the carpus, the proximal tooth of which is very small and contiguous with the large middle tooth. Grandidierella gilesi Chilton, 1921 is characterized by the densely setose gnathopods and the divergent merus of the gnathopod 2 in both sexes. Grandidierella halophila Wongkamhaeng, Pholpunthin Azman, 2012 possesses a long posteromedial projection on the male coxa 2. Grandidierella japonicoides sp. nov. closely resembles G. japonica Stephensen, 1938 in having stridulating ridges on the male gnathopod 1 carpus, but the former can be distinguished from the latter in the presence of a posteromedial projection on the male coxa 2 and the shapes of the gnathopod 1 carpus in both sexes. Grandidierella nana sp. nov. is a small species and has a wide and short carpus in the male gnathopod 1. Grandidierella pseudosakaensis sp. nov. is similar to G. osakaensis Ariyama, 1996; however, the former is different from the latter in the absence of a posterodistal projection on the male gnathopod 1 ischium and the growth process of the male gnathopods. A key to Grandidierella species in the Ryukyu Archipelago is provided.

Species of the Maera-clade collected from Japan. Part 3: genera Maera Leach, 1814, Meximaera Barnard, 1969 and Orientomaera Ariyama, 2018 (addendum), with a key to Japanese species of the clade (Crustacea: Amphipoda: Maeridae).

Two species of Maera Leach, 1814, a species of Meximaera Barnard, 1969 and a species of Orientomaera Ariyama, 2018 included in the Maera clade, are described from Japan. Maera loveni (Bruzelius, 1859) was collected from the Sea of Japan and can be distinguished from its congeners by the very large body size and the gnathopod 2 palm defined by a blunt tooth bearing a strong robust seta. Maera sagamiensis sp. nov. from Sagami Bay is characterized by the presence of small notches on the coxae 1-3. Meximaera mooreana (Myers, 1989) was collected from Wakayama Prefecture and has two distinct characters: the male gnathopod 2 with wide basis and the very long uropod 3. Morphological characters of the Japanese specimens resemble well those in the literature, but the mandibular palp article 1 is projected acutely. Orientomaera incisa sp. nov. was recently collected from Wakayama Prefecture and its gnathopods 2 in both sexes bear a distinctive incision on the palm. Keys to species of Meximaera in the world and Japanese species of the Maera-clade are provided. Fifteen species included in the Maera-clade occur in Japan.

Two species of Ceradocus collected from coastal areas in Japan, with description of a new species (Crustacea: Amphipoda: Maeridae).

Two species of the amphipod genus Ceradocus Costa, 1853 were collected from coastal areas in Japan: C. kiiensis sp. nov. from Wakayama Prefecture and C. laevis Oleröd, 1970 from Okinawa Prefecture. Both of the species share the asymmetrical male gnathopod 2, the larger male gnathopod 2 with strongly oblique palm and the uropod 3 with wide rami. Ceradocus kiiensis also has the palm with a single excavation in the larger male gnathopod 2 and the pleonites 1-3 with many dorsal teeth. This new species can be distinguished from its congeners by the absence of the anterodistal projection on the basis of the larger male gnathopod 2, the presence of the posterior teeth on the pleonal epimera 1-2, and others. Ceradocus laevis is characterized by the palm having triangular and small trapezoidal projections in the larger male gnathopod 2, the pereopods 5-7 bases with rounded posterodistal lobe, the pleonites and urosomites lacking dorsal teeth, and the pleonal epimera 1-2 without posterior teeth. This species can be easily distinguished from C. kiiensis by the smooth dorsal margins of the pleonites. A key to Ceradocus species in Japan is provided.

Species of the Maera-clade collected from Japan. Part 2: genera Austromaera Lowry Springthorpe, 2005 and Quadrimaera Krapp-Schickel Ruffo, 2000 (Crustacea: Amphipoda: Maeridae).

One species of Austromaera Lowry Springthorpe, 2005 and four species of Quadrimaera Krapp-Schickel Ruffo, 2000 included in the Maera clade, are described from Japan. Austromaera ariakensis sp. nov. is described, based on collections from Ariake Sea and can be distinguished from its congeners by the acutely produced coxa 1 and the merus of gnathopod 2 with a small posterodistal spine. Quadrimaera gotoensis sp. nov. from Goto Islands in Nagasaki Prefecture has a small quadrate excavation on the middle palmar margin of the male gnathopod 2. This new species is different from Q. mirandella Appadoo, Myers Fagoonee, 2002 having such an excavation, in the larger posterodistal tooth of the male gnathopod 2 propodus and the wider bases of the pereopods 5-7. Quadrimaera pacifica (Schellenberg, 1938) was collected from many localities from Iwate Prefecture to Ariake Sea. This species is characterized by the transverse palm of the male gnathopod 2 with the large posterodistal tooth, the small rounded excavation in the middle and the anterior lobe narrower and produced more distally than the posterior lobe. Morphology of Q. pacifica is variable in the posterior excavation of the male gnathopod 2 palm, the uropod 3 rami and the distal end of the telson. Quadrimaera quadrimana (Dana, 1853) from the south of Yakushima Island in Kagoshima Prefecture has a distinct palm of the male gnathopod 2 with three excavations. Quadrimaera setibasis sp. nov. collected from the intertidal zone in Osaka Prefecture has a setose basis of the pereopod 6 like Q. schellenbergi (Ruffo 1938), but the bases of the pereopods 5 and 7 are not setose. A key to species of Austromaera in the world is provided.

Species of the Maera-clade collected from Japan. Part 1: genera Maeropsis Chevreux, 1919 and Orientomaera gen. nov. (Crustacea: Amphipoda: Maeridae).

The Maera-clade is a group of maerid amphipod genera which has neither a falcate mandibular palp nor medially setose inner plates of maxillae 1 and 2. Two species of Maeropsis Chevreux, 1919 and four species of Orientomaera gen. nov. included in the clade, are described from Japan. Maeropsis okinawensis sp. nov. is described, based on collections from Okinawa Prefecture. It resembles M. cobia Krapp-Schickel, 2009, M. paphavasitae Wongkamhaeng, Coleman Pholpunthin, 2013, and M. serratipalma (Nagata, 1965). This new species differs from the latter three species in the long uropod 3. Maeropsis serratipalma is redescribed and newly recorded from Kanagawa, Osaka and Wakayama Prefectures. The new genus, Orientomaera, is described and is characterized by the mandibular palp article 1 without a distal tooth and the oblique palm of the gnathopod 2 with many robust setae. Orientomaera comprises four species: O. brevispina (Kim Kim, 1991) comb. nov. from Iwate, Fukui, Kyoto and Wakayama Prefectures and Ariake Sea; O. decipiens sp. nov. from Osaka and Wakayama Prefectures; O. obliquua sp. nov. from Osaka and Wakayama Prefectures; O. rotundicoxa sp. nov. from Kanagawa and Wakayama Prefectures. These species can be distinguished from one another by the coxa 1, the gnathopod 2 propodus, the pereopod 6 basis and the telson. Keys to species of Maeropsis and Orientomaera in the world are provided.

Five species of the family Cyproideidae (Crustacea: Amphipoda) from Japan, with the description of a new genus and two new species.

Five species of the family Cyproideidae (Crustacea: Amphipoda) are described from shallow sea in Japan. Cyproidea liodactyla Hirayama, 1978 was collected from Kanagawa and Shizuoka Prefectures and Ariake Sea. Morphological character of the antenna 1 in these specimens is different from the original description. Examining the paratypes of C. liodactyla, the shape of the antenna 1 in the holotype is revealed to be abnormal. Cyproidea okinawensis sp. nov. was collected from Okinawa Island. Its morphological characters resemble C. liodactyla and C. robusta Ren, 2006; however, this new species is different from the former in the smaller eyes, the narrower coxa 5 and the coloration, and from the latter in the ovoid telson. Metacyproidea gen. nov. is established with M. makie sp. nov. from Hachijo Island in Tokyo Prefecture as its type species. This new genus resembles Cyproidea, especially in the peduncular article 2 of antenna 1 with a distinct distal tooth and the posterodorsal end of urosomites with a strong projection. However, Metacyproidea can be distinguished from Cyproidea by the coalesced urosomites 2-3 and the antenna 1 with a 10-16-articulated flagellum. Moolapheonoides acutifalcatus Kobayashi & Ishimaru, 2005 and Terepeltopes dolichorhunia Hirayama, 1983 were also collected from Wakayama and Fukui Prefectures and Kanagawa, Shizuoka and Yamaguchi Prefectures, respectively. A key to species of the family Cyproideidae in Japan is provided.

Lysophosphatidylcholine acyltransferase 1 protects against cytotoxicity induced by polyunsaturated fatty acids.

The degree of fatty acid unsaturation in membrane phospholipids affects many membrane-associated functions and can be influenced by dietary consumption of fatty acids such as saturated fatty acids and polyunsaturated fatty acids (PUFAs). Cells must adapt to changes in composition of membrane fatty acids by regulating lipid-metabolizing enzymes. In this study, we investigated how cells respond to loading with excess PUFAs, such as arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. A lipidomics analysis revealed that dipalmitoylphosphatidylcholine (DPPC) was increased after the production of PUFA-containing phospholipids in cells loaded with PUFAs. An RNA interference screen of lipid-metabolizing enzymes revealed that lysophosphatidylcholine acyltransferase 1 (LPCAT1) was involved in the DPPC production. Moreover, LPCAT1 knockdown markedly enhanced the cytotoxicity induced by excess PUFAs. PUFA-induced cytotoxicity was dependent on caspase and unfolded protein response (UPR) sensor proteins inositol requiring 1α and protein kinase R-like endoplasmic reticulum kinase, suggesting that excess PUFAs trigger UPR-mediated apoptosis. In murine retina, in which PUFAs are highly enriched, DPPC was produced along with increase of PUFA-containing phospholipids. In LPCAT1 knockout mice, DPPC level was reduced and UPR was activated in the retina. Our results provide insight into understanding of the retinal degeneration seen in rd11 mice that lack LPCAT1.-Akagi, S., Kono, N., Ariyama, H., Shindou, H., Shimizu, T., Arai, H. Lysophosphatidylcholine acyltransferase 1 protects against cytotoxicity induced by polyunsaturated fatty acids.

Three new species of the Eriopisa group (Crustacea: Amphipoda: Eriopisidae) from Japan, with the description of a new genus.

Three new species of the Eriopisa group (Crustacea: Amphipoda: Eriopisidae) are described from coastal areas in Japan. Paraflagitopisa gen. nov. is established with P. excavata sp. nov. as its type species. This new genus is characterized by (1) entire lateral cephalic lobe, (2) unfused flagellum of antenna 2, (3) 3-articulated mandibular palp, (4) carpus of gnathopod 1 longer than propodus, (5) transverse palm of gnathopod 1, and (6) slender outer ramus of uropod 3 with long second article, and can be distinguished from the closely related genus, Flagitopisa, by the article 2 of mandibular palp longer than article 3, the undilated bases of pereopods 3-4, and the slender inner ramus of uropod 3. Psammogammarus lobatus sp. nov. is characterized by (1) male gnathopod 2 with excavated palm, (2) posterodistally projected bases of pereopods 5-7, (3) quadrate posteroventral corner of pleonal epimeron 3, (4) short inner ramus of uropod 3, and (5) article 2 of uropod 3 outer ramus longer than article 1. Victoriopisa wadai sp. nov. has the following characters: (1) eyes absent, (2) peduncle of antenna 1 not heavily setose, (3) accessory flagellum with 1-2 articles, (4) flagellum of antenna 2 composed of 2 long and 3 short articles, (5) gnathopod 2 in both sexes with excavated palm, (6) merus of pereopod 7 moderately expanded, and (7) ventral margin of pleonite 2 slightly setose. Key to species of the Eriopisa group in Japan is provided.

Membrane lipid saturation activates IRE1α without inducing clustering.

The unfolded protein response (UPR) is an adaptive stress response that responds to the accumulation of unfolded proteins in the lumen of the endoplasmic reticulum (ER) and that adjusts the protein-folding capacity to the needs of the cell. Perturbation of cellular lipids also activates the UPR. Lipid-induced UPR has attracted much attention because it is associated with the pathology of some metabolic diseases. However, how the lipid-induced UPR is activated remains unclear. We previously showed that palmitic acid treatment or knockdown of stearoyl-CoA desaturase in HeLa cells promotes membrane lipid saturation and activates the UPR. In this study, we compared UPR activation by membrane lipid saturation with UPR activation by conventional ER stressors that cause the accumulation of unfolded proteins such as tunicamycin and thapsigargin. Membrane lipid saturation induced autophosphorylation of inositol-requiring 1α (IRE1α) and protein kinase RNA-like ER kinase, but not the conversion of activating transcription factor-6α to the active form. A conventional ER stressor induced clustering of fluorescently tagged IRE1α fusion protein, but palmitic acid treatment did not, suggesting that IRE1α was activated without large cluster formation by membrane lipid saturation. Together, these results suggest membrane lipid saturation, and unfolded proteins activate the UPR through different mechanisms.

Decrease in membrane phospholipid unsaturation induces unfolded protein response.

Various kinds of fatty acids are distributed in membrane phospholipids in mammalian cells and tissues. The degree of fatty acid unsaturation in membrane phospholipids affects many membrane-associated functions and can be influenced by diet and by altered activities of lipid-metabolizing enzymes such as fatty acid desaturases. However, little is known about how mammalian cells respond to changes in phospholipid fatty acid composition. In this study we showed that stearoyl-CoA desaturase 1 (SCD1) knockdown increased the amount of saturated fatty acids and decreased that of monounsaturated fatty acids in phospholipids without affecting the amount or the composition of free fatty acid and induced unfolded protein response (UPR), evidenced by increased expression of C/EBP homologous protein (CHOP) and glucose-regulated protein 78 (GRP78) mRNAs and splicing of Xbox-binding protein 1 (XBP1) mRNA. SCD1 knockdown-induced UPR was rescued by various unsaturated fatty acids and was enhanced by saturated fatty acid. Lysophosphatidylcholine acyltransferase 3 (LPCAT3), which incorporates preferentially polyunsaturated fatty acids into phosphatidylcholine, was up-regulated in SCD1 knockdown cells. Knockdown of LPCAT3 synergistically enhanced UPR with SCD1 knockdown. Finally we showed that palmitic acid-induced UPR was significantly enhanced by LPCAT3 knockdown as well as SCD1 knockdown. These results suggest that a decrease in membrane phospholipid unsaturation induces UPR.