Patch-Clamp Study on Ion Channels in the Tonoplast of Nitellopsis obtusa

Cytoplasmic drops covered with the tonoplast were prepared frominternodal cells of Nitellopsis grown in fresh water. Applyingthe patch-clamp technique and the microinjection technique tosuch drops, we characterized the ion channels in the tonoplast.Both in cell-free patches and in the cytoplasmic-drop-attachedpatches, the tonoplast K⁺ channel was identified. The permeabilityratio between Na⁺ and K⁺ was calculated to be 0.2. This channelwould provide a molecular basis for the Na⁺/K⁺ exchange at thetonoplast. In cell-free patches, the K⁺channel was not activatedby Ca²⁺. However, in the case of attached patches, microinjectionof Ca²⁺ into a drop activated the K⁺ channel with a lag of afew seconds, suggesting that some cytoplasmic factor(s) maymediate the activation of the K⁺ channel by Ca²⁺. The conductanceof this channel was not changed by cytoplasmic Ca²⁺, but theprobability of opening increased markedly. In addition to theK⁺ channel, a second type of channel was also identified incell-free patches. This channel may be the Cl^– channel. ³ Present address: Department of Insect Physiology and Behavior,National Institute of Sericultural and Entomological Science,Tsukuba, Ibaraki, 305 Japan (Received August 6, 1990; Accepted December 6, 1990)     

Cyanoprotein: Developmental stage,sex and diapause-dependent expression,and synthesis regulation by juvenile hormone in the bean bug,Riptortus clavatus

Cyanoprotein (CP) synthesis was studied in nymphal and nondiapause adult, diapause adult, and juvenile hormone (JH) treated adult bean bugs, Riptortus clavatus. Hemolymph collected from bugs injected with [³⁵S]-methionine was analyzed by native polyacrylamide gel electrophoresis (PAGE) and fluorography, and CP synthesis was also determined quantitatively by rocket immunoelectrophoresis of hemolymph and counting. In the nymphal stages synthesis of CP-1, 2, 3, and 4 (with CP-4 synthesis predominant) reached a maximum at mid-instar and was not detected at each ecdysis, so that the synthetic activity of CPs changed cyclically in each instar. During the nymphal stages CP synthesis showed the same pattern and level in both females and males, and both diapause and nondiapause oriented bugs. In the adult stage, however, CP synthesis differed in the two sexes and nondiapause or diapause conditions. In nondiapause males CP synthesis was not detected in the adult, but in nondiapause females CP (only CP-1) was synthesized through the reproductive stages. CP-1 accumulated in the egg yolk together with vitellogenin. In diapause adults (both females and males) CP-1 to 4 were synthesized at a very low rate for over 2 months and accumulated in the hemolymph. JH or JH analog (JHA) methoprene and also long day condition, which terminate diapause, switched the main CP synthesis CP-4 to CP-1 in females. CP synthesis in diapause males stopped after JH(A) treatment. The activities of CP synthesis, thus, changed in developmental stages, sexes, and diapause. This is an excellent system for study of specific gene expression and switching controlled by insect hormones and sex. © 1992 Wiley-Liss, Inc.     

The direct involvement of cAMP-dependent protein kinase in the regulation of collagen synthesis by parathyroid hormone (PTH) and PTH-related peptide in osteoblast-like osteosarcoma cells (UMR-106).

The present study was performed to characterize the direct involvement of cAMP-dependent protein kinase (PKA) in the regulation of collagen synthesis by parathyroid hormone (PTH) and PTH-related peptide (PTHrP) in osteoblastic osteosarcoma cells, UMR-106. Sp-cAMPS (10(-4)M), a direct activator of PKA, as well as dibutyryl cAMP (dbcAMP, 10(-4)M) significantly inhibited collagen synthesis. Human (h) PTH-(1-34) (10(-7)M) and hPTHrP (10(-7) M) inhibited collagen synthesis to the same degree. Although Rp-cAMPS, which acted directly as an antagonist in the activation of PKA, did not affect collagen synthesis by itself, it significantly antagonized dbcAMP- and Sp-cAMPS-induced inhibition of collagen synthesis. Moreover, Rp-cAMPS antagonized PTH- and PTHrP-induced inhibition of collagen synthesis to the same degree. The present study first indicated that the activation of PKA was directly linked to the regulation of collagen synthesis by PTH in osteoblast and that PTHrP had the same effect on collagen synthesis presumably through the same mechanism as PTH.     

Case report on the death of a wild chimpanzee (Pan troglodytes verus)

The present paper gives a case report on the death of a wild young chimpanzee (Pan troglodytes verus) at Bossou, Guinea. The corpse of a 6.5-year-old male was found, and an autopsy suggested that he had died from some non-epidemic disease or from poisoning. Morphological measurements of the skeleton revealed that the chimpanzee was much smaller than corresponding individuals in captivity. The dental formula of the chimpanzee coincided with those of 5- to 5.5-year-olds in captivity. The death of this chimpanzee suggests that some of the individuals who had disappeared at Bossou had died of natural causes.     

Increase of Specific Activity, Electrophoretic Type-Transition and Gene Expression of Alkaline Phosphatase during Endodermal Differentiation of F9 Mouse Embryonal Carcinoma Cells

In F9 mouse embryonal carcinoma cells, the specific activity of alkaline phosphatase (ALPase) increases markedly during endodermal differentiation induced by retinoic acid (RA) treatment, but the specific 5'-nucleotidase activity of a similar ecto-phosphatase increases only temporally. Polyacrylamide disc gel electrophoresis showed that F9 cells express only type I ALPase, whereas RA-treated F9 cells express both type I and type II ALPases. Type II ALPase is a minor form on day 1 of RA treatment and becomes the major form on day 4. RA-treated F9 cells also expressed mRNAs for endoderm cell-specific molecules, such as α-fetoprotein, type IV collagen and laminin B1 chain, but their expression of M₂-type pyruvate kinase mRNA of an essential non-ectoenzyme remains constant throughout endodermal differentiation. Northern blot analyses showed that type I ALPase was encoded by a liver (L)/bone (B)/kidney (K)/placenta (P)-type mRNA. The expression of L/B/K/P-type ALPase mRNA was induced in RA-treated F9 cells, but its increase preceded that of ALPase specific activity. These results suggest that the expression of L/B/K-type ALPase is regulated at the translational and/or post-translational level. The differential inhibition of ALPases by L-phenylalanine/L-homoarginine and the thermal inactivation (56°C for 60 min) inferred that type II ALPase was also an L/B/K-type isozyme.     

Discovery of benzimidazole derivatives as orally active renin inhibitors: Optimization of 3,5-disubstituted piperidine to improve pharmacokinetic profile

We previously identified 2-tert-butyl-4-[(3-methoxypropyl)amino]-N-(2-methylpropyl)-N-[(3S,5R)-5-(morpholin-4-ylcarbonyl)piperidin-3-yl]pyrimidine-5-carboxamide 3 as a potent renin inhibitor. Since 3 showed unacceptably low bioavailability (BA) in rats, structural modification, using SBDD and focused on physicochemical properties was conducted to improve its PK profile while maintaining renin inhibitory activity. Conversion of the amino group attached at the 4-position of pyrimidine to methylene group improved PK profile and decreased renin inhibitory activity. New central cores with carbon side chains were explored to improve potency. We had designed a series of 5-membered azoles and fused heterocycles that interacted with the lipophilic S3 pocket. In the course of modification, renin inhibitory activity was enhanced by the formation of an additional hydrogen bonding with the hydroxyl group of Thr77. Consequently, a series of novel benzimidazole derivatives were discovered as potent and orally bioavailable renin inhibitors. Among those, compound 13 exhibited more than five-fold of plasma renin inhibition than aliskiren in cynomolgus monkeys at dose ratio.     

Primatology: the beginning

The journal Primates was founded by Kinji Imanishi (1902–1992) in 1957: It is the oldest and longest-running international primatology journal in the world. In this series of dialogues between Tetsuro Matsuzawa, Editor-in-Chief of Primates and the General Director of the Japan Monkey Centre (JMC) and Juichi Yamagiwa, former Editor-in-Chief of Primates and the Museum Director of the JMC, we look back at the achievements of our spiritual ancestors in primate research and talk about the back story of Imanishi and his fellow primatologists: founding the JMC as a research institute focused on primates and launching this journal. What was their motivation? What challenges did they face? What is their continued influence on the field right up to the present? What will be the legacy of our influence on the discipline?