321 research outputs found

    Dual effect of sympathetic hyperfunction on blood vessels in spontaneously hypertensive and stroke-prone spontaneously hypertensive rats

    Get PDF
    The sympathetic nervous system has been considered to be hyperactive from the very beginning after birth in spontaneously hypertensive and stroke-prone spontaneously hypertensive rats. This is a primary factor for the development and maintenance of hypertension via structural and functional alterations of the arteries and the heart. It is also described that the sympathetic hyperfunction probably play a protective role in necrosis of vascular smooth muscle cells in spontaneously hypertensive and stroke-prone spontaneously hypertensive rats.Biomedical Reviews 1996; 6: 57-68

    PITHD1 is essential for male fertilization

    Get PDF
    The proteasome is a protein-degrading molecular complex that is necessary for protein homeostasis and various biological functions, including cell cycle regulation, signal transduction, and immune response. Proteasome activity is finely regulated by a variety of proteasome-interacting molecules. PITHD1 is a recently described molecule that has a domain putatively capable of interacting with the proteasome. However, it is unknown as to whether PITHD1 can actually bind to proteasomes and what it does in vivo. Here we report that PITHD1 is detected specifically in the spermatids in the testis and the cortical thymic epithelium in the thymus. Interestingly, PITHD1 associates with immunoproteasomes in the testis, but not with thymoproteasomes in the thymus. Mice deficient in PITHD1 exhibit severe male infertility accompanied with morphological abnormalities and impaired motility of spermatozoa. Furthermore, PITHD1 deficiency reduces proteasome activity in the testis and alters the amount of proteins that are important for fertilization capability by the sperm. However, the PITHD1-deficient mice demonstrate no detectable defects in the thymus, including T cell development. Collectively, our results identify PITHD1 as a proteasome-interacting protein that plays a nonredundant role in the male reproductive system

    Ecological study of three hydrozoan species associated with three different nassariid gastropod species in the Seto Inland Sea

    Get PDF
    広島県竹原市近海において潮間帯に生息する腹足類アラムシロにエボシクラゲ属の1種,潮下帯に生息する腹足類ムシロガイ,キヌボラにそれぞれタマクラゲ,ミサキアミネウミヒドラのポリプが共生し,これらの調査期間中の共生率はそれぞれ9.1%,93.8%,83.8%であることが明らかとなった。これらの組合せには例外がみられず,宿主特異性は高かった。エボシクラゲ属の1 種の生殖体は6,9月,タマクラゲは8月のみ出現していたが,ミサキアミネウミヒドラは4–7,9,11,12月と頻繁に出現していた。また,ムシロガイ,キヌボラに比べて,アラムシロが底質中に潜行している時間は長い傾向が認められた。3種のポリプのうち,エボシクラゲ属の1種のみ厚い囲皮を備えるが,この形態は宿主が潮間帯に生息するため,干出による乾燥への適応であるかもしれない。また,このことが本種の共生率が低い原因の一つとして考えられる。Polyps of three hydrozoan species associated with three gastropod species of the family Nassariidae were observed in the Seto Inland Sea, Japan: (1) Leuckartiara sp. with Nassarius festivus occurring in the intertidal zone as well as (2) Cytaeis uchidae with N. livescens and (3) Stylactaria misakiensis with N. japonicus occurring in the sublittoral zone. Each hydrozoan species was highly host-specific, without any exceptional combination. The host utilization rates of the three hydrozoan species were markedly different; as such, the host utilization rate of Leuckartiara sp. occurring in the intertidal zone was less than 10%, whereas that of C. uchidae and S. misakiensis occurring in the subtidal zone ranged from 84% to 94%. Sexual reproduction was limited to summers in Leuckartiara sp. and C. uchidae, but it occurred yearround in S. misakiensis. The burying behavior of host shells differed among the three species; specifically, the intertidal N. festivus was buried in the sediments for over 20 h a day, while the subtidal C. uchidae and S. misakiensis were buried for less than 7 h a day. The ecological differences among the examined hydrozoan species associated with specific nassarrid hosts likely strengthen their niche segregation

    Tephra-stratigraphical study of the 1988-1989 eruption of Tokachi-dake Volcano, central Hokkaido

    Get PDF
    Twenty-three small-scale eruptions took place at Tokachi-dake from December 16, 1988 to March 5, 1989. The pyroclastic fall deposits, ballistic fragments, and pyroclastic surge and flow deposits were dispersed over the flank and leeward areas of the volcano. Because the pyroclasts of each eruption were well-preserved in snow during the winter, the stratigraphy and distribution of these deposits could be studied in detail. The volume of the pyroclastic fall deposits are nearly equal to those of the pyroclastic surge and flow deposits. The total volume of these pyroclasts is estimated to be 7.4×105 m3. Judging from the sequential changes of the volume and composition of the pyroclasts, the characteristic features of the eruption can be summarized as follows: At first, a vent was opened by ejection of altered rock fragments in December, 1988. Then, essential fragments were ejected in January, 1989. Finally the activity level of magma declined and the altered rock fragments content increased again in February to March, 1989

    PITHD1 is a proteasome-interacting protein essential for male fertilization

    Get PDF
    Hiroyuki Kondo, Takafumi Matsumura, Mari Kaneko, Kenichi Inoue, Hidetaka Kosako, Masahito Ikawa, Yousuke Takahama, Izumi Ohigashi, PITHD1 is a proteasome-interacting protein essential for male fertilization, Journal of Biological Chemistry, Volume 295, Issue 6, 2020, Pages 1658-1672, ISSN 0021-9258, https://doi.org/10.1074/jbc.RA119.011144

    The 1988-1989 explosive eruption of Tokachi-dake, central Hokkaido, Its sequence and mode

    Get PDF
    On December 16, 1988, after 26 years of dormancy since the last eruption in 1962, Tokachi-dake began to erupt from the 62-II crater. The eruption started with phreatic explosions. Then, on December 19, the activity changed into phreatomagmatic explosions of Vulcanian type and continued intermittently until March 5, 1989. Although the composition of the essential ejecta, mafic andesite, is similar to those of 1926 and 1962 eruptions, the mode of the present eruption is considerably diffrent The present eruption consists of a series of 23 discrete cannon-like explosions, being frequently accompanied with small-scale pyrcclastic surges and flows. The total volume of ejecta amounts to approximately 6×105 m3, of which about 20% is essential ejecta. A complete sequence of events was compiled and distribution maps of the ash-fall, ballistic blocks, and pyroclastic surges and flows were drawn for each of the larger eruptions. The pyrrolastic surges and flows of the present eruption were small scale, low temperature pyroclastic flows, rich in accessory clasts and unaccompanied by sector collapse. Therefore, the sudden melting of snow causing disastrous mudflows, as in the case of the 1926 eruption, fortunately did not occur
    corecore