Did food resource shortage cause Ryukyu-ayu extinction on Okinawa-jima Island? A clue based on morphological approach

Ichthyological Research - The Ryukyu-ayu population on Okinawa-jima Island went extinct suddenly in the late 1970s, but the cause remains unclear. Reports say that genetic diversity was not...     

Morphological development of larval and juvenile Alectis indica (Perciformes: Carangidae) reared in captivity

Larvae and juveniles of Alectis indica reared in captivity are described based on 47 specimens (3.2–32.0 mm in body length: BL). Development was typical for the tribe Carangini except for the presence of elongated fin filaments. Elongated dorsal-fin filaments were present at preflexion (3.2 mm BL). During flexion, the anal- and pelvic-fin rays elongated and the body deepened. The full complement of fin spines and rays was present by 7.1 mm BL. The larvae of A. indica could be differentiated from those of Alectis ciliaris, which also inhabits in the Indo-Pacific waters, by the presence of a ventral series of melanophores on the tail, elongated pelvic fins, and the timing of anal-fin spine migration. The rounded body and elongated fin rays of A. indica cause it to resemble venomous Cubomedusae.     

Abnormal gait,reduced locomotor activity and impaired motor coordination in Dgcr2-deficient mice

It has been suggested that the DGCR2 gene plays a role in the pathogenesis of 22q11.2 deletion syndrome. To analyze its function, we used our Dgcr2-knock-out/EGFP-knock-in mice (Dgcr2-KO mice). At 20-26 weeks of age, approximately 20% of Dgcr2-KO mice showed gait abnormalities with trembling and difficulty in balancing. Footprint test revealed awkward movements in Dgcr2-KO mice soon after they were placed on the floor. Once they started walking, their stride lengths were not different from wild-type mice. In short-term open field test, Dgcr2-KO mice travelled a significantly shorter distance and walked more slowly than wild-type mice during the initial 5 min after being placed in a new environment. In long-term open field test, Dgcr2-KO mice exhibited reduced cage activity compared to wild-type mice on the first day, but not on later days. Dgcr2-KO mice showed reduced latency to fall in the rotarod test, and the latency was not improved in the 3-day test. Histology revealed sparseness of cerebellar Purkinje cells in Dgcr2-KO mice. Our results suggest that Dgcr2 plays a role in motor control related to Purkinje cell function and that the deficiency of DGCR2 contributes at least to some of the symptoms of patients of 22q11.2 deletion syndrome.     

EHBP1L1 coordinates Rab8 and Bin1 to regulate apical-directed transport in polarized epithelial cells

The highly conserved Rab guanosine triphosphatase (GTPase) Rab8 plays a role in exocytosis toward the polarized plasma membrane in eukaryotic cells. In murine Rab8-deficient small intestine cells, apical proteins are missorted into lysosomes. In this study, we identified a novel Rab8-interacting protein complex containing an EH domain–binding protein 1–like 1 (EHBP1L1), Bin1/amphiphysin II, and dynamin. Biochemical analyses showed that EHBP1L1 directly bound to GTP-loaded Rab8 and Bin1. The spatial dependency of these complexes at the endocytic recycling compartment (ERC) was demonstrated through overexpression and knockdown experiments. EHBP1L1- or Bin1-depleted or dynamin-inhibited small intestine organoids significantly accumulated apical membrane proteins but not basolateral membrane proteins in lysosomes. Furthermore, in EHBP1L1-deficient mice, small intestine cells displayed truncated and sparse microvilli, suggesting that EHBP1L1 maintains the apical plasma membrane by regulating apical transport. In summary, our data demonstrate that EHBP1L1 links Rab8 and the Bin1–dynamin complex, which generates membrane curvature and excises the vesicle at the ERC for apical transport.