Differences in liver homogenates from Donryu, Fischer, Sprague-Dawley and Wistar strains of rat in the drug-metabolizing enzyme assay and the salmonella/hepatic S9 activation test

Comparison studies for detecting differences between liver microsome and S9 preparations from 4 strains (Donryu, Fischer, Sprague-Dawley, Wistar) of young male rats were carried out with pretreatment of the animals by inducers such as PCBs and PB plus 5,6-BF. Each microsome fraction was assayed for the enzymic activity of metabolism of model substrates such as aniline, benzophetamine, BP, DMN and 7-ethoxycoumarin. The hepatic S9 sample was also compared, as regards its metabolizing ability to activate 9 pre-mutagens (2AA, AAF, o-AAT, BP, DAB, DMBA, DMN, m-PDA, quinoline) to directly acting mutagens in the Salmonella/hepatic S9 activation test by using TA98, TA100 and TA1537 strains with or without cytochrome P450 inhibitors (SKF-525A, metyrapone, 7,8-benzoflavone).In the enzymic assay with PCBs-induced microsomes, BP hydroxylation revealed a strain-specific difference: the microsomes from Fischer and Wistar rats were more effective for metabolizing BP than those from the other strains of rat. The effect of induction by PB plus 5,6-BF for Fischer rats showed relatively higher enzymic activity in the same induction group. Other microsomes prepared from rats with and without induction by PB plus 5,6-BF did not show a clear-cut strain dependency in the enzymic activities assayed.In the mutation experiments with hepatic S9 samples, the examination of DAB and quinoline revealed a marked strain difference when S9 samples prepared from PCBs-pretreated and PB-plus-5,6-BF-induced rats were used: the S9 sample from Fischer rats was available for activating the two pre-mutagens to directly acting mutagens. No marked difference in the metabolic activation of the remaining 7-pre-mutagens was observed on other S9 preparations.In examinations of mutagenicity activities with the use of three inhibitors, the two S9 preparations made with the two induction methods showed inhibition profiles closely similar to each other. However, there were minor differences in the profiles by these inhibitors.From these findings it was concluded that Fischer rat-liver S9 is useful for detecting mutagens in the metabolic activation test, when induction by PB plus 5,6-BF was used in the Ames Salmonella test.     

Kinetics of the Unrolling of the Second Leaves Detached from Rice Seedlings by Blue Light

Unrolling due to blue light (B) irradiation of the second leavesdetached from 8-day-old rice (Oryza saliva L.) seedlings wassimilar to that reported previously for nondetached leaves.The effect of B was counteracted by irradiation with red light(R). The counteracting effect of R was reversed by subsequentirradiation with far-red light (FR). When the detached leaf was irradiated with B passed througha 1-mm-wide slit 5, 8, 10, 12 or 15 mm from the leaf tip, irradiation10 mm from the leaf tip was the most effective. The effect of a 1 mm-wide-B irradiation 10 mm from the leaftip was counteracted by a 1 mm-wide-R irradiation at the sameposition, but not by irradiations at the other points. The counteractingeffect of R was reversed by a 1 mm-wide-FR irradiation at thesame position. This suggests that the excitation or the reactionof the B photoreceptor(s) is affected directly by the PFR formof phytochrome. The dose-response curve for the unrolling caused by B showeda simple Bunsen-Roscoe relation without two peaks, which differsfrom that for the phototropism in Avena caused by B. (Received August 21, 1980; Accepted December 20, 1980)     

Isolation and some properties of extracellular d-glucosyltransferases and d-fructosyltransferases from Streptococcus mutans serotypes c, e, and f

Extracellular d-glucosyltransferases (GTase) and d-fructosyltransferases (FTase) were isolated from Streptococcus mutans IB (serotype c), B14 (e), and OMZ175 (f) by chromatofocusing, followed by hydroxyapatite column chromatography. The GTases isolated from serotypes c, e, and f are basic proteins (pI 7.4). The serotype c and e enzymes have two protein components having M_r 173 000 and 158 000 and the enzyme of the serotype f one component having M_r 156 000. The GTases of all the serotypes showed a K_m value for sucrose of 10–14mm and an optimum pH 5.5–6.0 for enzyme activity, and their activities were enhanced by the presence of primer Dextran T10. The α-d-glucans synthesized by the purified GTases are water soluble and primarily consist of (1→6)-α-d-glucosidic linkage (41–66 mol/100 mol) and α-d-(1→3,6)-branch linkage (6–20 mol/100 mol), but significant proportions of α-d-(1→3), α-d-(1→4), and α-d-(1→3,4) linkages (11, 6, and 14 mol/100 mol, respectively) were detected in the serotype c α-d-glucan. The isolated FTases of the serotypes c, e, and f are acidic enzymes (pI 4.6) and consist of two components having M_r 84 000 and 76 000 for the serotype c enzyme, and 106 000 and 84 000 for the serotypes e and f enzymes, respectively. The K_m value for sucrose was 6, 10, and 17mm for the serotypes c, e, and f enzymes, respectively, and the optimum pH of enzymic activity 5.5–6.0. Reactivity with Concanavalin A, susceptibility to acid hydrolysis, and paper chromatography of the hydrolyzates suggested that the water-soluble β-d-fructans synthesized by the purified FTases were of the inulin-type and had chemical structures somewhat different among the serotypes.     

Life cycle of an endangered riffle beetle,Leptelmis gracilis Sharp (Coleoptera: Elmidae), in the Hiikawa River system,Shimane prefecture,Japan

We studied the life cycle of the riffle beetle Leptelmis gracilis Sharp, 1888 from a population located in a river stream with lotic environments. Samples were collected monthly, between September 2018 and August 2019, from a tributary of the Hiikawa River in Izumo city, Shimane Prefecture, Honshu, Japan. Larvae were separated into five distinct groups based on size. The first and last instar larval sizes were identified through rearing methods. From these results, we determined that the larval stage of this species consists of five instars. From the monthly evaluations, the number of individuals corresponding to each instar period suggested that last-instar larvae were dominant in May and that new adults emerged from July to August. Landing and pupation were estimated to occur from May to June. Monthly observations revealed that mature eggs were present in the female abdomen from April to June, as well as from August to September. It is, therefore, predicted that overwintering adults mainly oviposit from spring to early summer, while new adults oviposit from late summer to early autumn.     

Molecular cloning of putative chloroplastic cysteine synthase in Leucaena leucocephala

Journal of Plant Research - Cysteine biosynthesis is directed by the successive commitments of serine acetyltransferase, and O-acetylserine (thiol) lyase (OASTL) compounds, which subsequently frame...     

Characteristics of microbial fermentation and potential digestibility of fiber in the hindgut of dugongs (Dugong dugon)

The number of microorganisms in the hindgut of dugongs (Dugong dugon) were estimated and their in vitro volatile fatty acid (VFA) production and degradation of eelgrass measured. Scanning electron microscopy showed that some rod bacteria attached to the surface of plant tissue degraded and eroded the cell walls. Number of starch-, lactate-, cellobiose-, pectin-, xylan- and cellulose-utilizing bacteria, sulfate-reducing bacteria and methane-producing bacteria were estimated at 10⁹ ～ 10¹⁰ colony forming units g^?1. Microorganisms degraded the cellulose and noncellulolytic components of the eelgrass, and about 47.3% of dry matter was degraded after 36?h in vitro incubation. The total VFA concentration was 10.5?mmol?dL^?1 at 36?h incubation, which included 55.7?mol% acetate, 18.0?mol% n-butyrate and 15.1?mol% propionate. The gas composition of in vitro fermentation was 68.4% carbon dioxide, 22.2% methane and 9.4% hydrogen.     

Contextual Effects of Scene on the Visual Perception of Object Orientation in Depth

We investigated the effect of background scene on the human visual perception of depth orientation (i.e., azimuth angle) of three-dimensional common objects. Participants evaluated the depth orientation of objects. The objects were surrounded by scenes with an apparent axis of the global reference frame, such as a sidewalk scene. When a scene axis was slightly misaligned with the gaze line, object orientation perception was biased, as if the gaze line had been assimilated into the scene axis (Experiment 1). When the scene axis was slightly misaligned with the object, evaluated object orientation was biased, as if it had been assimilated into the scene axis (Experiment 2). This assimilation may be due to confusion between the orientation of the scene and object axes (Experiment 3). Thus, the global reference frame may influence object orientation perception when its orientation is similar to that of the gaze-line or object.     

Human cathelicidin antimicrobial peptide LL-37 promotes lymphangiogenesis in lymphatic endothelial cells through the ERK and Akt signaling pathways

Molecular Biology Reports - LL-37, the only member of the cathelicidin family of cationic antimicrobial peptides in humans has been shown to exhibit a wide variety of biological actions in addition...     

Identification of a New Interaction Mode between the Src Homology 2 Domain of C-terminal Src Kinase (Csk) and Csk-binding Protein/Phosphoprotein Associated with Glycosphingolipid Microdomains

Proteins with Src homology 2 (SH2) domains play major roles in tyrosine kinase signaling. Structures of many SH2 domains have been studied, and the regions involved in their interactions with ligands have been elucidated. However, these analyses have been performed using short peptides consisting of phosphotyrosine followed by a few amino acids, which are described as the canonical recognition sites. Here, we report the solution structure of the SH2 domain of C-terminal Src kinase (Csk) in complex with a longer phosphopeptide from the Csk-binding protein (Cbp). This structure, together with biochemical experiments, revealed the existence of a novel binding region in addition to the canonical phosphotyrosine 314-binding site of Cbp. Mutational analysis of this second region in cells showed that both canonical and novel binding sites are required for tumor suppression through the Cbp-Csk interaction. Furthermore, the data indicate an allosteric connection between Cbp binding and Csk activation that arises from residues in the βB/βC loop of the SH2 domain.