Distribution of Japanese temperate bass, <Emphasis Type="Italic">Lateolabrax japonicus</Emphasis>, eggs and pelagic larvae in Ariake Bay

We collected eggs and larvae of the Japanese temperate bass, Lateolabrax japonicus, and present horizontal and temporal changes of distribution relative to development and growth during the species pelagic life history in Ariake Bay. Sampling was conducted from the inner to central region (11 sampling stations) of Ariake Bay using a plankton net (80 cm diameter, 0.5-mm mesh) from November 2000 to February 2001. Both eggs and larvae were collected most abundantly in mid-December. The CPUE of eggs in the surface layer was higher than the middle layer, which is in contrast to that at the larval stage. Most eggs were collected around the central and western regions of the bay. The distribution of eggs shifted vertically to the middle layer with development. Yolk-sac larvae were collected in the central region of the bay, and preflexion and flexion larvae were more abundantly collected in the inner region of the bay. The body length of larvae around the inner bay was larger than in the central region. The pelagic life history can be summarized as follows: eggs are distributed around the central region of the bay and eggs and larvae expand their distribution to the inner and shallower waters with growth. We conclude that the shift of vertical distribution in pelagic stages and the hydrographic features of the middle layer form one of the mechanisms enabling the inshore migration of L. japonicus.     

Dietary daidzein,but not genistein,has a hypocholesterolemic effect in non-ovariectomized and ovariectomized female Sprague-Dawley rats on a cholesterol-free diet

We compared the effects of two major isoflavones, daidzein and genistein, on lipid metabolism in rats. Daidzein (150 mg/kg diet), genistein (150 mg/kg diet), daidzein and genistein (1:1, 300 mg/kg diet), or control diets were fed to 4 groups of 6-week-old ovariectomized (Ovx) and non-Ovx Sprague Dawley rats for 4 weeks. Dietary daidzein, but not genistein, reduced serum and hepatic total cholesterol levels significantly relative to that by the control group, regardless of whether the rats had undergone ovariectomy. Genistein did not exhibit any physiological effects on lipid levels, but did affect genes involved in cholesterol metabolism. These results indicate that daidzein and genistein may influence lipid regulation via differing modes of action.     

Pairing strategy after today’s failure: unpaired termites synchronize mate search using photic cycles

Animals must search for other individuals under spatially and temporally fluctuating environments. During mate searches, search timing is critical to increase encounter rate and internal oscillating clocks often play important roles in synchronization. On the other hands, some species living in areas with no or reduced periodicity do not show endogenous circadian rhythm, where little is known about how they determine search timing. Termites usually live within logs and underground with little light fluctuations, but also come out of their nests during mating flight season. After swarming, termites run on the ground to search for mates. If they fail to find mates on the flight day, they need to continue searching until a day to succeed. Here we found that unpaired termites show daily search–rest cycles and restrict searching activity to a certain period of the day by responding to photic cycles. The search–rest cycles were diel rhythmic and synchronized with light–dark cycles. Termites also showed periodic (period length ≈ 18 h) search–rest patterns under constant darkness. These results indicate that the diel rhythm is caused by the internal oscillating clocks which are entrained to the photic cycles. The search activity in light–dark cycles was observed only at a specific time during the light period, which matches approximately the time of swarming flight. Our results suggest that termites adaptively regulate their daily searching activity, if they fail to encounter mates at the flight day.     

DIX Domains of Dvl and Axin Are Necessary for Protein Interactions and Their Ability To Regulate β-Catenin Stability

The N-terminal region of Dvl-1 (a mammalian Dishevelled homolog) shares 37% identity with the C-terminal region of Axin, and this related region is named the DIX domain. The functions of the DIX domains of Dvl-1 and Axin were investigated. By yeast two-hybrid screening, the DIX domain of Dvl-1 was found to interact with Dvl-3, a second mammalian Dishevelled relative. The DIX domains of Dvl-1 and Dvl-3 directly bound one another. Furthermore, Dvl-1 formed a homo-oligomer. Axin also formed a homo-oligomer, and its DIX domain was necessary. The N-terminal region of Dvl-1, including its DIX domain, bound to Axin directly. Dvl-1 inhibited Axin-promoted glycogen synthase kinase 3beta-dependent phosphorylation of beta-catenin, and the DIX domain of Dvl-1 was required for this inhibitory activity. Expression of Dvl-1 in L cells induced the nuclear accumulation of beta-catenin, and deletion of the DIX domain abolished this activity. Although expression of Axin in SW480 cells caused the degradation of beta-catenin and reduced the cell growth rate, expression of an Axin mutant that lacks the DIX domain did not affect the level of beta-catenin or the growth rate. These results indicate that the DIX domains of Dvl-1 and Axin are important for protein-protein interactions and that they are necessary for the ability of Dvl-1 and Axin to regulate the stability of beta-catenin.     

DNA Replication of Human Papillomavirus Type 31 Is Modulated by Elements of the Upstream Regulatory Region That Lie 5′ of the Minimal Origin

The viral replication factors E1 and E2 of papillomaviruses are necessary and sufficient to replicate plasmids containing the minimal origin of DNA replication in transient assays. Under physiological conditions, the upstream regulatory region (URR) governs expression of the early viral genes. To determine the effect of URR elements on E1 and E2 expression specifically, and on the regulation of DNA replication during the various phases of the viral life cycle, we carried out a systematic replication study with entire genomes of human papillomavirus type 31 (HPV31), a high-risk oncogenic type. We constructed a series of URR deletions, spacer replacements, and point mutations to analyze the role of the keratinocyte enhancer (KE) element, the auxiliary enhancer (AE) domain, and the L1-proximal end of the URR (5′-URR domain) in DNA replication during establishment, maintenance, and vegetative viral DNA amplification. Using transient and stable replication assays, we demonstrate that the KE and AE are necessary for efficient E1 and E2 gene expression and that the KE can also directly modulate viral replication. KE-mediated activation of replication is dependent on the position and orientation of the element. Mutation of either one of the four Ap1 sites, the single Sp1 site, or the binding site for the uncharacterized footprint factor 1 reduced replication efficiency through decreased expression of E1 and E2. Furthermore, the 5′-URR domain and the Oct1 DNA binding site are dispensable for viral replication, since such HPV31 mutants are able to replicate efficiently in a transient assay, maintain a stable copy number over several cell generations, and amplify viral DNA under vegetative conditions. Interestingly, deletion of the 5′-URR domain leads to increased transient and stable replication levels. These findings suggest that elements in the HPV31 URR outside the minimal origin modulate viral replication through both direct and indirect mechanisms.     

Purification and characterization of an endo-polygalacturonase from a mutant of Saccharomyces cerevisiae.

An extracellular endo-polygalacturonase (PGase) produced by a mutant of Saccharomyces cerevisiae was isolated. The enzyme was regarded, immunologically, as a PGase belonging to the Kluyveromyces marxianus group. The enzyme had properties similar to the PGase from K. marxianus in heat and pH stability, and N-terminal amino acid sequence. However, the enzyme showed different properties in optimum pH and temperature, molecular weight, and reactivity in antiserum against PGase from K. marxianus, indicating that the enzyme has a different molecular structure from the PGase from K. marxianus.     

Organization, Structure, and Evolution of the Nonadult Rat β-Globin Gene Cluster

The β-globin gene cluster of Wistar rat was extensively cloned and the embryonic genes were mapped and sequenced. Four overlapping λ Dash recombinant clones cover about 31 kb and contain four nonadult β-globin genes, 5′–ε1–γ1–γ2–ψγ3–3′. The ε1 and γ2 are active genes, since their protein products were detected in the fetal stage of the rat (Iwahara et al., J Biochem 119:360–366, 1996). The γ1 locus might be a pseudogene, since the ATA box in the promoter region is mutated to GTA; however, no other defect is observed. The ψγ3 locus is a truncated pseudogene because a 19-base deletion, which causes a shift of the reading frame, is observed between the second nucleotide of the putative codon 68 and codon 76. A sequence comparison suggests that the ψγ3 might be produced by a gene conversion event of the proto-γ-globin gene set. Possible histories of the evolution of rat nonadult β-globin genes are discussed. Received: 6 August 1998 / Accepted: 12 February 1999     

关于日本扁柏人工林光能利用效率的研究（I）——群落生产结构与现存量、生长量和光能利用效率

本研究用相关生长法与分层割取法相结合测定的21年生日本扁柏人工林的现存量为160t／ha,生长量为16.5t／ha·a,净光能利用率为0.64%。在日本福岡地区这样的光能利用率不算高。根据各层的干物质重与D2·H的相关生长关系计算了各部分的垂直分布。以太阳能多点测定计测算了林冠上部和林冠内各层太阳辐射量的季节变化。绘制了生产结构图。通过对林冠各部位叶的测定,证明了充分郁闭的日本扁柏林同日本柳杉林一样,可以区分为圆锥形、圆柱形树冠。其叶面积数和叶量密度分别为：35±5cm2／g,495g／m3;45±5cm2／g,222g／m3。以材积解析和群落生产结构、光能分布为依据论述了生产结构对光能利用的限制。