著者

Endo Hideki Niizawa Nobuharu Komiya Teruyuki Kawada Shinichiro Kimura Junpei Itou Takuya Koie Hiroshi Sakai Takeo

出版者

Zoological Society of Japan

雑誌

Zoological science (ISSN:02890003)

巻号頁・発行日

vol.24, no.10, pp.1005-1011, 2007-10

被引用文献数

2 17

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The gross anatomy of the mastication system of the giant anteater (Myrmecophaga tridactyla) was examined by means of three-dimensional image analysis. The anteater rotates the mandibles medially and laterally to control its tongue when it is elongated and to house it when it is relaxed. Three-dimensional CT image analysis demonstrated that the shape and size of the oral cavity changes drastically when the mandibles are rotated. The oral cavity expands bilaterally when the dorsal part of the mandibles bend medially. Macroscopic observations and muscle-weight data supported the observation that the superficial temporal and medial pterygoid muscles act as the main medial and lateral rotators of the mandible, respectively. The low height of the mandibular ramus and the incomplete zygomatic arch in this species represent adaptations for the rotational movement of the mandibles, since they both contribute to the medially oriented transmission of force from the temporal muscles and to preventing collision between the mandibles and the cranium during the rotational movement.

著者

Masaki Tadakatsu Endo Katsuhiko Kumagai Kanji

出版者

Zoological Society of Japan

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.5, no.5, pp.p1051-1057, 1988-10

被引用文献数

1

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In the butterfly, Polygonia c-aureum L., a physiological mechanism underlying the photoperiodic control of seasonal-morph development involves a summer-morph-producing factor (SMPH). Amounts of SMPH present in the brain-extracts of Polygonia pupae as well as in those of the silkmoth. Bombyx mori, were evaluated by Polygonia pupal assay for SMPH. The factors responsible for SMPH-activity in the Polygonia and Bombyx brain-extracts were heat-stable (95℃ for 5min), but they were thought to be peptide hormones since the brain-extracts became SMPH-inactive by hydrolyzing with trypsin (24hr at 25℃). According to the Sephadex G-50 gel-filtration pattern of SMPH-activity, the ultimate molecular weight of SMPH was though to be 4500, which is almost the same size as the small prothoracicotropic hormone purified from the silkmoth, B. mori (4K-PTTH or bombixin: M. W. 4400). This finding is also supported by evidence in our present study that 2 (out of 4) Sephadex G-50 fractions judged as being SMPH-active showed 4K-PTTH-activity by Papilio pupal assay. However, the factor showing SMPH-activity was not thought to be identical with the one showing 4K-PTTH-activity in P. c-aureum since they were separated by reversed-phase HPLC.

著者

Kurihara Takeo Shikatani Mayu Nakayama Kouji Nishida Mutsumi

出版者

Zoological Society of Japan

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.23, no.11, pp.999-1008, 2006-11

被引用文献数

11

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In many benthic organisms with a planktonic larval stage, local populations have different morphology. Such difference may arise from some of the following proximate mechanisms. “Local recruitment (LR)”: no larvae move between local populations, and segregated populations possess alleles coding for locally adaptive morphology. “Intragenerational selection (IS)”: larvae move between local populations, and individuals with alleles for locally adaptive morphology survive after recruitment. “Phenotypic plasticity (PP)”: larvae move between local populations and show phenotypic plasticity to adapt to a locality after recruitment. We examined which mechanism explains our finding that a planktonic developer Turbo coronatus coronatus (Gastropoda) had significantly longer spines on its shell on more exposed shores at scales of < 2 km. Experiments at Ishigaki Island, Okinawa, Japan, showed the following results. (a) Shorter- and longer-spined populations occurring within 2 km showed non-significant ϕ low st values (−0.0040 to 0.00095) for the mitochondrial DNA COI region. This suggests no segregation of the local populations, supporting the mechanisms IS and PP. (b) T. c. coronatus generated significantly longer spines 70 days after being transplanted to the habitat of a longer-spined population, supporting IS and PP. (c) Individuals caged in the sea for 79 days generated longer spines than individuals in the laboratory, supporting PP. In conclusion, shore-specific morphology of T. c. coronatus arises most likely from phenotypic plasticity and possibly from intragenerational selection.

著者

Matsui Masafumi Nishikawa Kanto Misawa Yasuchika Tanabe Shingo

出版者

Zoological Society of Japan

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.24, no.7, pp.746-751, 2007-07

被引用文献数

5

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We conducted an electrophoretic survey to examine systematic relationships of a lotic-breeding salamander Hynobius okiensis endemic to Dogo Island of the Oki Islands, Japan, with several lentic and lotic-breeding Japanese species. Genetically H. okiensis with 2n=56 chromosomes was closer to the lentic-breeding H. nebulosus group (H. nebulosus and H. dunni) with the same chromosome number than to the lotic-breeding H. naevius group (H. naevius and H. kimurae) and H. boulengeriwith 58 chromosomes. Chromosome number reduction from 58 to 56, possibly accompanied with a change in breeding environment from streams to still waters, is estimated to have first occurred in the nebulosus group of Hynobius. A reversal only in breeding habits then seems to have followed in steep, montane environments of the small island of Dogo, resulting in the speciation of H. okiensis.

著者

Sawada Isamu Koyasu Kazuhiro

出版者

Zoological Society of Japan

雑誌

Zoological Science (ISSN:02890003)

巻号頁・発行日

vol.8, no.3, pp.p575-578, 1991-06

被引用文献数

2