Characterization of Aquimarina hainanensis isolated from diseased mud crab Scylla serrata larvae in a hatchery

Mass mortality due to necrosis signs occurred in hatchery-reared zoea stage larvae of the mud crab Scylla serrata in Okinawa, Japan, and a causative bacterium was isolated. In this study, we identified and characterized the bacterium by genome analysis, biochemical properties and pathogenicity. The bacterium was a Gram-negative, non-motile, long rod, forming yellow colonies on a marine agar plate. It grew at 20–33°C (not at 37°C) and degraded chitin and gelatin. Phylogenetic analysis of the 16S rRNA gene sequence identified the bacterium as Aquimarina hainanensis. Genome sequence data obtained from Illumina MiSeq generated 29 contigs with 3.56 Mbp in total length and a G + C content of 32.5%. The predicted 16 chitinase genes, as putative virulence factors, had certain homologies with those of genus Aquimarina. Experimental infection with the bacterium conducted on larvae of four crustacean species, brine shrimp Artemia franciscana, freshwater shrimp Caridina multidentata, swimming crab Portunus trituberculatus and mud crab S. serrata, revealed that this bacterium was highly virulent to these species. The present study suggests that the bacterium caused mass mortality in mud crab seed production was A. hainanensis and can be widely pathogenic to crustaceans.     

大叶榉愈伤组织诱导与继代培养的影响因素

以大叶榉种子的子叶、胚轴、顶芽、嫩枝叶片和茎段等为外植体 ,对大叶榉进行愈伤组织诱导及继代培养研究 .结果表明 :不同外植体的愈伤组织诱导能力有差异 ,其诱导率按高低顺序排列依次为子叶、胚轴、叶片、茎段和顶芽 ;愈伤组织质地、颜色、生长速度与基本培养基、外源激素有很大的关系 ,基本培养基以 WPM培养基最好 ;最佳诱导培养基不适合继代保存 ;在培养基中附加抗氧化剂并调整激素种类 ,可较好地防止褐变现象     

Acorn dispersal and predation patterns of four tree species by wood mice in abandoned cut-over land

We compared patterns of acorn dispersal and predation by wood mice among four tree species (Quercus serrata, Quercus crispula, Castanea crenata, and Juglans mandshurica var. sieboldiana) that are abundant in cool temperate woodlands. We devised an acorn dispersal experiment using 400 magnet-inserted acorns and a magnetic locator in a 1.8-ha study plot, which spanned a cut-over area and an adjacent deciduous forest. Ten wire mesh baskets, each containing 40 acorns (10 acorns per species), were placed on the border between these two habitat types. About 13.0% (n = 52) of the total acorns remained in the baskets, while 77.3% (n = 309) were dispersed throughout the study plot and subsequently retrieved using the magnetic locator. Microhabitat, distance, and burial depth of transported acorns were significantly different among species. In the cut-over area, J. mandshurica var. sieboldiana acorns were dispersed under fallen trees or branches and near stumps, and were buried deeply in the soil. Dispersal distances of J. mandshurica var. sieboldiana acorns were significantly greater than those of Q. serrata acorns. The number and microhabitat of transported acorns significantly differed between habitat types. J. mandshurica var. sieboldiana acorns were dispersed in the cut-over area rather than in the forest. For all four species, the numbers of acorns delivered to fallen trees or branches, stumps, and crumbled soil with overhang under any vegetation type were greater in the cut-over area than in the forest.     

Screening of extracts of Japanese woods for melanin biosynthesis inhibition

The effects of 120 methanol extracts prepared from bark and heartwood of 69 types of Japanese wood on the melanin production of B16 melanoma cells were examined. The melanin content of B16 melanoma cells was determined spectrophotometrically at 405nm. The extracts were also examined for their effects on cell viability. We found that the methanol extracts of Fagus crenata (buna, wood, 100μg/ml), Sapium sebiferum (Nankinhaze, wood, bark, 10μg/ml), and Zelkova serrata (keyaki, wood, 10μg/ml) greatly inhibited the melanin production of B16 melanoma cells without significant cytotoxicity. However, these extracts did not inhibit tyrosinase activity at the concentration of 100μg/ml. These findings indicate that the depigmenting mechanism of these extracts involves the suppression of some pigmenting signals in stimulating melanogenesis rather than the inhibition of tyrosinase activity. Part of this study was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003     

榉树茎尖的培养

选用成年榉树 Schneideriana 的当年生嫩枝作为外植体,经常规消毒后,接种于附加不同质量浓度的激素BA、NAA、2,4-D的MS培养基上,诱导茎尖萌芽.结果表明:诱导芽萌发的最适宜的培养基为MS BA( 1.0 mg·L-1),继代培养后,在每个芽的基部又可长出3～7个小芽;小芽在MS BA(0.5 mg·L-1) CH(500 mg·L-1)培养基上培养30～40 d,即可长成小植株;在 1/2MS IBA(0.5 mg·L-1)的生根培养基上培养3～4周后可形成正常植株.     

The influences of boiling and drying treatments on the behaviors of tension wood with gelatinous layers in <Emphasis Type="Italic">Zelkova serrata</Emphasis>

This study examined how boiling and drying treatments influenced various physical properties of the tension wood with gelatinous fibers (G-fibers) of a 29-yearold Zelkova branch. By boiling treatment, tension wood with numerous G-fibers contracted considerably in the longitudinal direction and the longitudinal Young’s modulus decreased in spite of the water-saturated condition. The drying treatment caused green tension wood and boiled tension wood with numerous G-fibers to shrink longitudinally and increased their longitudinal Young’s moduli. These specific behaviors in tension wood were highly correlated with the proportion of G-fibers in a specimen and were probably caused by the microscopic behavior of cellulose microfibril (CMF) in the gelatinous layers (G-layers). The longitudinal shrinkage of tension wood due to drying suggests the existence of a hygro-sensible, noncrystalline region in the CMF, which is abundant in the G-layer. Furthermore, the noncrystalline region in the CMF softens during boiling treatment, resulting in the reduction of the longitudinal Young’s modulus in tension wood. The longitudinal contraction of tension wood with G-fibers by boiling might be caused by the tensile growth stress remaining in green G-layers. However, no changes were detected in the 004 d-spacing of cellulose crystal in tension wood from the boiling and drying treatments, regardless of the proportion of G-fibers.     

育苗基质对榉树容器苗质量的影响

【目的】为了筛选出适于榉树容器苗生长的最佳基质配比,以提高榉树容器苗的培育质量。【方法】以泥炭土、珍珠岩、蛭石、锯木屑和腐殖土5种材料为原料,按照一定的比例配制成6种基质,以此6种配方基质为供试的育苗基质(其处理编号分别为T1、T2、T3、T4、T5、T6),选择10 cm×5 cm×5 cm的无纺布袋作为育苗容器,进行了榉树容器育苗试验。测定了榉树容器苗的出苗率、形态指标、生物量及生理指标等19个指标,并采用隶属函数法对以不同配方基质培育的容器苗的苗木质量进行了综合评价。【结果】6种基质处理的出苗率从大到小依次为T3>T5>T1>T2>T6>T4,其中T3基质处理的出苗率最高,T4基质处理的出苗率最低,T3基质处理的出苗率是T4基质处理的出苗率的3.47倍;T1基质处理的苗高、地径均极显著高于其他基质处理的,T2基质处理的叶片数显著高于除T1和T5外的其他基质处理的。T2基质处理的侧枝数显著高于其他基质处理的,不同基质处理间容器苗的高径比、侧根数、主根长均无显著差异;T1基质处理的茎干质量、根干质量、苗木干质量及其质量指数均极显著高于其他基质处理的,不同基质处理间容器苗的茎根比无显著差异;T1基质处理的根系活力强度和叶绿素a含量均极显著高于除T2外的其他基质处理的,T2基质处理的叶绿素总量极显著高于除T1外的其他基质处理的,不同基质处理间容器苗的叶绿素b、叶绿素a/b之值均无显著差异,T4基质处理的净光合速率最低,极显著低于其他基质处理的。【结论】采用模糊数学的隶属函数法综合评价得出:以T1基质(其配比为:腐殖土∶泥炭土∶珍珠岩=2∶1∶1)培育的榉树容器苗其质量最好,这种配方基质是榉树容器苗的最佳育苗基质。     

锯缘青蟹死亡的组织病理学初步观察

对2008年8月福建省泉州市某海水场养殖锯缘青蟹中发生的死亡现象，开展锯缘青蟹的组织病理学研究。解剖可见肌肉明显坏死、溶解；头胸甲储积大量暗黄色体液，经福尔马林固定成固态物质；光镜下发现病蟹的中肠腺上皮细胞坏死、细胞质中出现大型的包涵体；电镜下发现病蟹的细胞质中有长约为500hm、宽约为200hm杆状结构的疑似杆状病毒存在。     

大叶榉人工栽培技术研究

榉树是国家二级保护树种，人工大面积栽培在国内尚未见报道。实践证明，榉树人工造林后生长良好。１年生苗高平均可在１ｍ以上，最高达１。７５ｍ，１０年生树，年平均高生长０．７８ｍ，胸径０．７２ｃｍ，优于同等条件下的马尾松，次于杉树，是优良的速生硬阔叶树种。人工林５０年可达工艺成熟，每亩年平均利润约７０００元，宜种子繁殖。