Evaluation of downward movements of Japanese eel Anguilla japonica inhabiting brackish water areas

This study evaluated the size and age distributions and otolith microchemistry of the Japanese eel Anguilla japonica in freshwater and brackish water areas in the Aki and Tsuchikawa rivers for 1 year, and in brackish water areas in the Asahi River for 3 years to understand the movements of Japanese eels between continental habitats of different salinity after recruitment (n = 759). For all three rivers, the total length (L_T) and age distributions were consistent; yellow eels captured in the upper brackish water (Aki River: 353.5 ± 77.4 mm and 3.0 ± 0.8 years; Tsuchikawa River: 287.7 ± 87.3 mm and 3.7 ± 1.3 years; Asahi River: 418.2 ± 112.1 mm and 4.2 ± 1.7 years) were smaller and younger than not only those in the fresh water of the two rivers but also those in the lowest brackish water sampling areas (Aki River: 436.0 ± 71.6 mm and 3.8 ± 1.1 years; Tsuchikawa River: 370.9 ± 121.7 mm and 4.9 ± 2.3 years; Asahi River: 558.5 ± 85.9 mm and 5.7 ± 1.7 years). In the Asahi River, these tendencies were found throughout the 3 years. Otolith analysis indicated that the majority of the eels captured in the lowest brackish water areas had moved down from upstream. These results suggest that Japanese eels inhabiting saline water generally move from the upper estuary as they grow. The upper estuary can be an important area for the management of this species because these eels spend their early continental growth life there.     

Fish oils and aggression or hostility

Fish oils have long been known to protect the heart from ischemic heart disease and fatal arrhythmia. Recently they have also been suggested to protect the heart in a literal sense! Although not all reports on fish oils and psychiatric disorder support the latter notion, many of them claim that fish oils were effective. The point is that, different from currently prescribed psychiatric medicines, fish oils do not do harm to any part of the body. We have been working on the effects of fish oils on aggressive behavior and hostility. Unfortunately this area of research is not mature yet. The number of related papers is rather limited, so we will take aggression and/or hostility in a broader sense including oppositional behavior, violence etc. in this review. We found fourteen intervention studies checking the effects of fish oils on aggressive behavior. Eleven of them showed the aggression/hostility-controlling effects of fish oils one way or another. We did not try to summarize those effects by meta-analysis, because we thought that the methods of research were too heterogeneous. The mechanisms as to how fish oils affect aggression/hostility is not clear yet, but several possible mechanisms have been postulated. Among them, activation of the serotonergic neuron system is the most promising. The research area of fish oils and aggression/hostility is clearly important from the medical and social points of view.     

Effect of Inositol Deficiency on Cellular Permeability of the Inositol Exacting Yeast

Inositol deficiency caused the abnormalities of permeability of the cell envelope of the inositol exacting yeasts. In the case of Schizosaccharomyces pombe, in which the marked leakage of cellular free-pool fraction was not detected, the uptake activity of glucose or methylglucoside decreased in inositol deficiency, especially in aerobic condition. Investigations on the compositions of lipids and fatty acids showed that the change in fatty acid composition was not so remarkable as that in phosphatides in inositol deficiency. One of the main causes of low transport activity may be due to the change in phosphatides, but not due to that in fatty acids, possibly. Intracellular contents of glucose was not less in inositol deficiency than in sufficiency. These results suggest that inositol deficiency caused the low activity of uptake, which might not be, however, the primary cause of low fermentative activity.

In the case of Saccharomyces cerevisiae Ino^– mutant A–21–20, the similar results about permeability and lipid analyses were obtained in inositol deficiency.     

Effects of Inositol Deficiency on Respiratory and Fermentative Activities of Inositol-exacting Yeast,Schizosaccharomyces pombe

Inositol deficiency of Schizosaccharomyces pombe did not induce significant change of contents of various cellular components except for phospholipids and inositol. The most remarkable decrease in inositol content by the deficiency occurred in the mitochondrial fraction. Electronmicroscopic observation of the inositol-deficient cells of Sch. pombe showed no remarkable thickening of cell wall as occurred in the inositol-exacting mutant of Saccharomyces cerevisiae Strain A–21–20.

Marked loss of fermentative activity under the aerobic condition was caused from inositol deficiency without significant change of activities of respiration and anaerobic fermentation. This seemed to indicate elevated regulatory control of the fermentative activity by oxygen in the inositol-deficient Sch. pombe.

Phosphorylative activities of intact cells and the isolated mitochondria coupled with oxidation was also remarkably suppressed by inositol deficiency.     

Effect of Various Inhibitors on Lipase Action of Thermophilic Fungus Humicola lanuginosa S-38

The hydrolysis of olive oil by the Humicola lipase was inhibited by the addition of n-alcohols, fatty acids and surface active agents. The inhibition of n-alcohols was overcomed by the addition of more substrate but not by the addition of more enzyme. The inhibition of fatty acids and bile salts was eliminated by adding calcium ion. It was concluded that the inhibition of the Humicola lipase by n-alcohols, fatty acids and bile salts was not due to inactivation of the enzyme directly but due to the displacing of the substrate from the oil/water interface, thus blocking the enzyme from the substrate.     

Biological Activity and Mode of Action of a Specific Antiphage Substance,AFS

Purified AFS (anti-filamentous phage substance) produced by Streptomyces lavendulae AM–7a showed specific antiphage activity against the male specific, deoxyribonucleic acid-containing filamentous phages of Escherichia coli without any activity against other DNA-phages nor the male-specific ribonucleic acid-containing phages of E. coli. AFS brought about no inactivation of free particles of filamentous phage, fl, nor the receptor of the host cells for the phage, while it showed strong killing effect against the fl-infected host cells at the concentration below 0.01 μg/ml. Antiphage activity of AFS might be due to its highly specific killing effect only on the E. coli cells infected with the filamentous DNA phages, while it exerted no effect on the growth of the unifected E. coli nor other microorganisms. Killing by AFS seemed to require the energy metabolism of the phage-infected host cells. Macro-molecular synthesis and respiration of the infected host cells were inhibited soon after the addition of small amounts of AFS without any cell lysis.     

Mass spectrometric and mutational analyses reveal Lys-6-linked polyubiquitin chains catalyzed by BRCA1-BARD1 ubiquitin ligase

The breast and ovarian cancer suppressor BRCA1 acquires significant ubiquitin ligase activity when bound to BARD1 as a RING heterodimer. Although the activity may well be important for the role of BRCA1 as a tumor suppressor, the biochemical consequence of the activity is not yet known. Here we report that BRCA1-BARD1 catalyzes Lys-6-linked polyubiquitin chain formation. K6R mutation of ubiquitin dramatically reduces the polyubiquitin products mediated by BRCA1-BARD1 in vitro. BRCA1-BARD1 preferentially utilizes ubiquitin with a single Lys residue at Lys-6 or Lys-29 to mediate autoubiquitination of BRCA1 in vivo. Furthermore, mass spectrometry analysis identified the Lys-6-linked branched ubiquitin fragment from the polyubiquitin chain produced by BRCA1-BARD1 using wild type ubiquitin. The BRCA1-BARD1-mediated Lys-6-linked polyubiquitin chains are deubiquitinated by 26 S proteasome in vitro, whereas autoubiquitinated CUL1 through Lys-48-linked polyubiquitin chains is degraded. Proteasome inhibitors do not alter the steady state level of the autoubiquitinated BRCA1 in vivo. Hence, the results indicate that BRCA1-BARD1 mediates novel polyubiquitin chains that may be distinctly edited by 26 S proteasome from conventional Lys-48-linked polyubiquitin chains.     

Delimitation of cryptic species of the Scytosiphon lomentaria complex (Scytosiphonaceae,Phaeophyceae) in Japan,based on mitochondrial and nuclear molecular markers

Scytosiphon lomentaria (Scytosiphonaceae, Ectocarpales) is believed to include some cryptic species, particularly in the Pacific. We attempted to delimit these species in Japan using mitochondrial cox1 and cox3 and nuclear ITS2 and the second intron of the centrin gene (cetn‐int2). Fifty‐three cox1+cox3 mitotypes, 26 ITS2 ribotypes and 45 cetn‐int2 haplotypes were found in 107 samples collected from 33 localities in Japan. Based on phylogenetic analyses, similar sequence types were grouped into ten mitogroups, eight ribogroups and six cetn‐int2 haplogroups (sequence‐type groups). From the molecular trees and combinations of the mito‐, ribo‐ and haplogroups, three cryptic species were apparent (Groups I–III). Group I, widely distributed on Pacific coasts, was highly supported by all molecular trees, whereas Groups II (North Pacific) and III (Northwestern Pacific and Australasia) were more closely related to each other. However, sequence‐type‐group combinations that would be characteristic of hybrids between Groups II and III were not detected, suggesting no gene flow between the two Groups. Further investigations of an additional 127 sympatrically growing plants supported the absence of gene flow between Groups II and III. Four samples did not belong to any of the Groups I–III and possibly represent additional species.     

Discovery of Two Novel Viruses Expands the Diversity of Single-Stranded DNA and Single-Stranded RNA Viruses Infecting a Cosmopolitan Marine Diatom

Recent studies have suggested that diatom viruses are an important factor affecting diatom population dynamics, which in turn are important in considering marine primary productivity. The marine planktonic diatom Chaetoceros tenuissimus Meunier is a cosmopolitan species and often causes blooms off the western coast of Japan. To date, two viruses, C. tenuissimus DNA virus (CtenDNAV) type I and CtenRNAV type I, have been identified that potentially affect C. tenuissimus population dynamics in the natural environment. In this study, we successfully isolated and characterized two additional novel viruses (CtenDNAV type II and CtenRNAV type II). This paper reports the basic characteristics of these new viruses isolated from surface water or sediment from the Hiroshima Bay, Japan. The physiological and morphological characteristics of the two new viruses were similar to those of the previously isolated viruses. However, the amino acid sequences of the structural proteins of CtenDNAV type II and CtenRNAV type II were clearly distinct from those of both type I viruses, with identity scores of 38.3% and 27.6%, respectively. Our results suggest that at least four genetically distinct viruses sharing the same diatom host are present in western Japan and affect the population dynamics of C. tenuissimus. Moreover, the result that CtenRNAV type II lysed multiple diatom species indicates that RNA viruses may affect various diatom populations in the natural environment.