A complete dietary review of Japanese birds with special focus on molluscs

Birds often hold important positions in the food webs of ecosystems. As a result, interactions between birds and their prey have attracted attention not only in ecology, but also in fields like agriculture and conservation. Avian food resources are well researched in Japan, however there is no database critically reviewing molluscs as a food resource for birds. Here, we present a new database reviewing dietary information for all Japanese bird species. In addition to addressing general diet categories and specific food habits for each bird, we include detailed data on the molluscan prey observed for all species that consume them. The information within this database was collected through intense literary review to provide a complete look at bird species historically present around the country. We also include new information on snail species found in the upper digestive tract of harvested wild birds. This database is publicly available in the Zenodo repository. The information should aid research around the Japanese archipelago, especially projects involving birds or molluscs

Dynamic alteration of Orbit localization in germline stem cells (GSCs) and spermatogonial division.

<p>(A–H) GFP-Orbit (green) and DNA (blue) are shown. (D, F, G, H) anti-γ-tubulin immunostaining (red). (I) GFP-tubulin (green), anti-Orbit immunostaining (red), and DNA (blue). (J, K) GFP-tubulin (green), anti-spectrin antibody immunostaining (red), and DNA (blue). (A) Tip of a testis from a <i>nos-Gal4>UAS-GFP-Orbit</i> male. Hub cells are encircled by a dotted line. Orbit is localized on the spectrosome of a GSC (larger arrowhead), kinetochores of a GSC at metaphase (smaller arrowhead), central spindle microtubules of a presumptive GSC (smaller arrow), and fusome plug formed at the midbody of a presumptive GSC (larger arrow). (B) A gonialblast undergoing the first division at metaphase. (C) Late anaphase of a gonialblast. (D) In the second spermatogonial division, two centrosomes (red) are connected by a single spectrosome (arrowhead). Orbit is more abundant on spectrosomes and around centrosomes attached to the spectrosome, than on distal centrosomes. (E) A 2-cell cyst of dividing spermatogonia at anaphase. Note the contractile ring (arrowhead) between two cells. (F) Two 4-cell cysts and part of a 16-cell cyst at interphase. Most of the centrosomes (red) are not associated with fusomes at interphase. (G) An 8-cell cyst in which γ-tubulin foci (yellow) have become evident at the onset of the third mitotic division. (H) Prophase to prometaphase of the third spermatogonial division. Every centrosome pair (red) orients towards the fusome, and one of the two centrosomes (arrowheads) is captured by the fusome. (I) Immunostaining of an 8-cell cyst at metaphase. Orbit is localized on kinetochores and part of the fusome (arrowheads). (J, K) An 8-cell spermatogonial cyst undergoing mitosis; (J) normal control male and (K) <i>orbit⁷</i> mutant male. The mutant fusome appears to be disconnected. At least two mitotic spindles (arrows) have been detached from the fusome.</p

Close association of Orbit with F-actin contained in a fusome of a spermatocyte cyst.

<p>(A–C″) CFP and YFP fluorescence images, and fluorescence resonance energy transfer (FRET)/CFP emission ratio images in spermatocytes. (A–A″) Positive control for FRET experiment in early spermatocytes. Co-expression of CFP-histone 2B (A) to YFP-histone 2B (A′) was induced in early spermatocytes using the UAS/Gal4 system. (A″) A FRET/CFP emission ratio was calculated using MetaMorph software. The distribution of the ratio between the minimum value (darkest blue) and maximum value (lightest red) is represented by the 8-step color indicator in the intensity-modulated display mode. Note the distinct YFP emission in nuclei of early spermatocytes after CFP excitation. It is well known that histone H2B forms a dimer in a nucleosome, and therefore, the YFP emission is generated because of FRET from CFP to YFP. (B–B″) CFP and FRET/CFP ratio images of spermatocytes with co-expression of Venus-Orbit and CFP-actin. CFP (B) and FRET/CFP ratio images (B″) of spermatocytes with co-expression of Venus-Orbit and CFP-actin. (C–C″) A spermatocyte with co-expression of CFP-actin (C) and YFP-Asl (C′), as a negative control for the FRET experiment. (D) The average FRET relative intensity in nuclei of spermatocytes with co-expression of CFP-Histone 2B and YFP-Histone 2B, fusomes of spermatocytes with co-expression of CFP-actin and Venus-Orbit, and fusomes in spermatocytes with co-expression of CFP-actin and YFP-Asl. The FRET relative intensity was calculated and represented according to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058220#pone.0058220-Tsvetkov1" target="_blank">[44]</a>. (E) F-actin and Orbit are components of fusomes extending in a spermatocyte cyst. RFP-actin (red), GFP-Orbit (green), and DNA (blue) are shown. (F) F-actin depolymerization induced by treatment with cytochalasin D does not influence Orbit localization on fusomes, or maintenance of the fusome structure. Scale bar = 10 µm.</p

The <i>orbit</i> gene is required for development of fusomes and ring canals in spermatocyte cysts.

<p>(A, B) Immunostaining of early spermatocyte cysts from normal males and from <i>orbit⁷</i> mutant males by using anti-α-spectrin antibody for fusome visualization (red) and anti-phospho-tyrosine for ring canal observation (green). DNA staining (blue). Note the abnormal fusomes, which failed to elongate (arrow) or branch in the mutant cysts. The ring canal marker failed to be incorporated in the lumen of ring canals (arrowhead). (C) A normal branched fusome structure with constant thickness in a wild-type early spermatocyte cyst at the S2 stage. (D) A less-branched fusome structure in the mutant spermatocyte cyst. The abnormal fusome becomes thinner in places or disconnected (arrows). (E) Immunodetection of ring canals in early spermatocyte cysts using anti- phospho-tyrosine antibody. Note the formation of ring canals with constant diameter between every nucleus (blue) in wild-type spermatocytes. Note also that normal ring canals are shaped by a continuous hollow structure (inset). (F) In early spermatocytes from <i>orbit⁷</i> mutant males, disconnected ring canals are observed in the mutant cysts (inset). Abnormal ring canals with larger diameters (arrows) are observed in early spermatocytes from <i>orbit⁷</i> mutant males. Scale bar = 10 µm.</p

Inhibition of microtubule polymerization does not influence the maintenance of Orbit localization on fusomes.

<p>Green is GFP-tubulin, red is mRFP-Orbit, and blue is DAPI staining. (A) An early spermatocyte cyst incubated without colchicine. Note the cytoplasmic microtubule structures and distinct Orbit localization on growing fusomes. (B) An early spermatocyte cyst treated with colchicine; a branched fusome structure is intact. (C, D) Microtubule degradation by colchicine treatment: (C), a metaphase I cell without colchicine treatment; (D), a meiotic cell treated with colchicine. Scale bar = 10 µm.</p

Orbit/CLASP Is Required for Germline Cyst Formation through Its Developmental Control of Fusomes and Ring Canals in <em>Drosophila</em> Males

<div><p>Orbit, a <i>Drosophila</i> ortholog of microtubule plus-end enriched protein CLASP, plays an important role in many developmental processes involved in microtubule dynamics. Previous studies have shown that Orbit is required for asymmetric stem cell division and cystocyte divisions in germline cysts and for the development of microtubule networks that interconnect oocyte and nurse cells during oogenesis. Here, we examined the cellular localization of Orbit and its role in cyst formation during spermatogenesis. In male germline stem cells, distinct localization of Orbit was first observed on the spectrosome, which is a spherical precursor of the germline-specific cytoskeleton known as the fusome. In dividing stem cells and spermatogonia, Orbit was localized around centrosomes and on kinetochores and spindle microtubules. After cytokinesis, Orbit remained localized on ring canals, which are cytoplasmic bridges between the cells. Thereafter, it was found along fusomes, extending through the ring canal toward all spermatogonia in a cyst. Fusome localization of Orbit was not affected by microtubule depolymerization. Instead, our fluorescence resonance energy transfer experiments suggested that Orbit is closely associated with F-actin, which is abundantly found in fusomes. Surprisingly, F-actin depolymerization influenced neither fusome organization nor Orbit localization on the germline-specific cytoskeleton. We revealed that two conserved regions of Orbit are required for fusome localization. Using <i>orbit</i> hypomorphic mutants, we showed that the protein is required for ring canal formation and for fusome elongation mediated by the interaction of newly generated fusome plugs with the pre-existing fusome. The <i>orbit</i> mutation also disrupted ring canal clustering, which is essential for folding of the spermatogonia after cytokinesis. Orbit accumulates around centrosomes at the onset of spermatogonial mitosis and is required for the capture of one of the duplicated centrosomes onto the fusome. Moreover, Orbit is involved in the proper orientation of spindles towards fusomes during synchronous mitosis of spermatogonial cysts.</p> </div

Orbit immunostaining and expression of Orbit fused with fluorescence tags in testis tip cells.

<p>(A) Lower magnification view of cells derived from testis tip. Microtubules (green), anti-Orbit immunostaining (red), and DNA (blue) are shown. Orbit is localized on a spectrosome in a 2-cell cyst (smaller filled arrowhead), and on a fusome in an 8-cell cyst (smaller filled arrow). It is also localized on ring canals in a 16-cell cyst (open arrowhead). The larger arrow shows Orbit localization on pieces of fusome formed in a partial spermatocyte cyst at the S2b stage, i.e., the early stage of the growth phase. Inset; a 4-cell spermatogonial cyst at metaphase. (B) Hub cells (arrow) surrounded by several germline stem cells (GSCs). Orbit (red) is highly concentrated in the cytoplasm of hub cells, and on single spectrosomes (arrowheads) in the GSCs. (C) Orbit immunolocalization on ring canals in an early spermatocyte cyst. (D) Expression of GFP-Orbit in an early spermatocyte cyst at the S3 stage, i.e., the middle of the growth phase (green in D, D′). Anti-spectrin immunostaining (red in D, D″) to visualize the fusome is shown. (E) Expression of mRFP-Orbit in a partial spermatid cyst at the onion stage (red in E, E′). Anti-phospho-tyrosine immunostaining (green in E, E″) to visualize ring canals is indicated. Scale bar = 10 µm.</p

Orbit/CLASP Is Required for Myosin Accumulation at the Cleavage Furrow in <i>Drosophila</i> Male Meiosis

<div><p>Peripheral microtubules (MTs) near the cell cortex are essential for the positioning and continuous constriction of the contractile ring (CR) in cytokinesis. Time-lapse observations of <i>Drosophila</i> male meiosis showed that myosin II was first recruited along the cell cortex independent of MTs. Then, shortly after peripheral MTs made contact with the equatorial cortex, myosin II was concentrated there in a narrow band. After MT contact, anillin and F-actin abruptly appeared on the equatorial cortex, simultaneously with myosin accumulation. We found that the accumulation of myosin did not require centralspindlin, but was instead dependent on Orbit, a <i>Drosophila</i> ortholog of the MT plus-end tracking protein CLASP. This protein is required for stabilization of central spindle MTs, which are essential for cytokinesis. Orbit was also localized in a mid-zone of peripheral MTs, and was concentrated in a ring at the equatorial cortex during late anaphase. Fluorescence resonance energy transfer experiments indicated that Orbit is closely associated with F-actin in the CR. We also showed that the myosin heavy chain was in close proximity with Orbit in the cleavage furrow region. Centralspindlin was dispensable in Orbit ring formation. Instead, the Polo-KLP3A/Feo complex was required for the Orbit accumulation independently of the Orbit MT-binding domain. However, <i>orbit</i> mutations of consensus sites for the phosphorylation of Cdk1 or Polo did not influence the Orbit accumulation, suggesting an indirect regulatory role of these protein kinases in Orbit localization. Orbit was also necessary for the maintenance of the CR. Our data suggest that Orbit plays an essential role as a connector between MTs and the CR in <i>Drosophila</i> male meiosis.</p></div

Genetic interaction between <i>orbit</i> and <i>zip</i> in male meiotic cytokinesis appeared in onion stage spermatids.

<p>Genetic interaction between <i>orbit</i> and <i>zip</i> in male meiotic cytokinesis appeared in onion stage spermatids.</p