Effect of dietary history and algal traits on feeding rate and food preference in the green sea urchin Strongylocentrotus droebachiensis

Feeding behaviour is influenced by a variety of factors, including nutritional requirements, the quality of available foods, and environmental conditions. We examined the effect of two factors, food morphology and dietary history, on the feeding rate and preference of the sea urchin Strongylocentrotus droebachiensis. Standardizing food shape and structure did not alter urchins' expected preference for the native kelp Laminaria longicruris over the invasive alga Codium fragile ssp. tomentosoides. However, when foods containing L. longicuris were shaped to mimic the algae, the C. fragile mimic was consumed more rapidly than the kelp mimic. Dietary history had no effect on single diet feeding rate. Urchins feeding on C. fragile consistently consumed twice as much (by mass) as those fed kelp, regardless of their previous diet. Despite higher feeding rates on C. fragile, urchins feeding on this alga were unable to compensate for its low energetic content and ingested less energy. Dietary history had a short-term effect on food preference, with urchins tending to prefer less familiar foods. Our findings suggest that urchins feed on C. fragile at a high rate, due to ease of handling and/or compensatory feeding, and that they do not a have strict preference hierarchy. Rather, food choice appears to reflect active maintenance of a mixed diet.     

Prenylated acetophenones from Melicope obscura and Melicope obtusifolia ssp. obtusifolia var. arborea and their distribution in Rutaceae

Four prenylated acetophenones 2,6-dihydroxy-4-geranyloxyacetophenone (1), 4-geranyloxy-2,6,β-trihydroxyacetophenone (2), 2,6-dihydroxy-4-geranyloxy-3-prenylacetophenone (3), and 4-geranyloxy-3-prenyl-2,6,β-trihydroxyacetophenone (4) have for the first time been isolated from Melicope obscura (1 and 2) and Melicope obtusifolia ssp. obtusifolia var. arborea (3 and 4). The distribution of prenylated acetophenones in Rutaceae is reviewed and the results, including the new records, indicate that prenylated acetophenones are valuable as chemotaxonomic markers for the subfamily Rutoideae, tribe Xanthoxyleae sensu Engler.     

Molecular diversity of Photobacterium damselae ssp. piscicida from cultured amberjacks (Seriola spp.) in Japan by pulsed-field gel electrophoresis and plasmid profiles

AIMS: This study deals with a pulsed-field gel electrophoresis (PFGE) for discriminating between the genetic variants of Photobacterium damselae ssp. piscicida, and characterizing of Japanese field isolates by PFGE together with plasmid profiles and antimicrobial resistances. METHODS AND RESULTS: A total of 74 field isolates from cultured Japanese amberjacks were used for PFGE. SmaI and NotI enabled to clearly differentiate strains and we obtained 24 of combined PFGE profiles which were distinct from those of classical Japanese and USA reference strains, and classified them into three groups (Ia-Ic). By plasmid size, we could classify these field isolates into three plasmid types, pA-pC. The predominant PFGE-type Ia was closely associated with plasmid-type pA, and Ib showed a moderate association with pB. Ic was closely associated with pC, and multiresistant isolates were not observed in this type. Whole-genomic variations were also observed between isolates having identical detection areas, fish species and detection-date by PFGE. CONCLUSION: Molecular diversity of P. damselae ssp. piscicida could be detected by PFGE, and some relations among the PFGE-type, plasmid-type and antimicrobial resistances were observed in Japanese field isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: This study indicated that some genetic transition might have occurred in P. damselae ssp. piscicida around the Japanese seas, and PFGE can be a valuable tool for the epidemiological study of this highly homogeneous subspecies.     

Quantitative analysis of a stand of Pinus densiflora undergoing succession to Quercus mongolica ssp. crispula : II. Growth and population dynamics of Q. mongolica ssp. crispula under the P. densiflora canopy

We report here the results of an 8-year study of the growth and population dynamics of Quercus mongolica ssp. crispula in a Pinus densiflora stand in a state of succession. In 1998, there were 169 Q. mongolica ssp. crispula individuals in a 400-m² plot under the P. densiflora canopy. This number remained nearly constant between 1998 and 2005. Mean recruitment of new individuals was 11 year⁻¹, while mean mortality was 12 year⁻¹. Of the 35 individuals ≥60 cm in height existing in 1998, 30 were still surviving in 2005. We were able to represent the height growth of Q. mongolica ssp. crispula individuals as H=30 [1+21.96 exp(−0.0839t)]⁻¹, with t = years since 1998 and H = height in meters. Using this equation we predict that by 2015 the mean height of Q. mongolica ssp. crispula trees in the stand will exceed those of understory trees, such as Rhus trichocarpa and Prunus maximowiczii. Once above the understory stratum, the Q. mongolica ssp. crispula trees can be expected to grow more rapidly due to the better light conditions, thereby rapidly reaching the canopy stratum of the P. densiflora stand.     

Reversible inhibition of the pollen germination and the stigma penetration in Crocus vernus ssp. vernus (Iridaceae) following fumigations with NO2, CO, and O3 Gases

We assessed the pollen hydration, the pollen germination, and the stigma papilla penetration of CROCUS VERNUS subsp. VERNUS (Iridaceae) after 2 h fumigations with O (3), NO (2), and CO gases within humidified (90 - 100 % RH) box experiments. When the pollen and the pistil were separately fumigated, the pollen retained the capacity to emit a tube which penetrated papilla, and the stigma papillae retained the receptivity; when the pistils were first pollinated and then fumigated, the capacity of pollen to hydrate was not affected, but the germination was significantly reduced. The vulnerability to gases became evident at 0.3 ppm O (3), 0.2 ppm NO (2), and 0.5 ppm CO. The inhibition curves as a function of the gas concentrations were of an exponential type, and they saturated at 2 ppm NO (2), 25 ppm CO, and 0.5 ppm O (3), with germination percentages of 17 %, 27 %, and 60 %, respectively. Both the pollen germination and the papilla penetration were fully restored by prolonging for 60 - 90 min the incubation at 90 - 100 % RH, after the cessation of fumigations. The vulnerability of the pollen-papilla system is discussed.     

驴源兽疫链球菌的分离鉴定及多位点序列分型分析

【目的】本研究采集了新疆地区驴腺疫病料,从样品中分离鉴定可疑病原菌并对其进行基因水平的分型与进化分析。【方法】对采集的新疆地区某驴场驴腺疫病驴颌下淋巴结拭子进行细菌分离培养,对2个分离株(HT111、HT321)进行染色、培养、生化试验、药敏试验,对其16S rRNA及SeM基因进行测序和进化分析,并通过PCR扩增7个管家基因,利用多位点序列分型(MLST)方法鉴定其分子分型。【结果】2个分离株均属马链球菌兽疫亚种,其中HT111对测试的13种抗生素中的3种(青霉素、克拉霉素和四环素)耐药,HT321对8种抗生素(阿莫西林、头孢呋辛、头孢噻呋、青霉素、克拉霉素、克林霉素、土霉素和四环素)耐药。序列分型发现了一种新的ST型为ST420 (HT321),分离株HT111为ST179型。【结论】本研究在新疆地区首次分离了驴源马链球菌兽疫亚种,并鉴定出一个新的ST型(ST420),为驴腺疫的流行病学提供了参考数据。     

秸秆浸提液漂浮栽培对不结球白菜产量及相关品质特性的影响

以1/4园试营养液为对照,以腐熟发酵的农业秸秆(苋菜和番茄植株残体)浸提液模拟富含N、P的水体进行不结球白菜(Brassica campestris ssp.chinensis Makino)的漂浮栽培,对茎叶的单株鲜质量和干质量及叶片的VC、可溶性蛋白质、蔗糖、果糖、葡萄糖含量及可溶性糖总含量进行了比较分析。结果表明:在24 d的栽培周期内,随生长时间的延长,处理组和对照组茎叶的单株鲜质量和干质量均呈增加趋势,但从第10天开始,处理组茎叶的单株鲜质量和干质量均显著低于对照组。栽培初期叶片VC含量均最高且处理组叶片VC含量显著低于对照组;从第10天开始,叶片VC含量降低,但处理组叶片VC含量与对照组无显著差异。处理组与对照组叶片可溶性蛋白质含量均呈波动的变化趋势,但总体差异不显著。处理组叶片蔗糖含量总体上与对照组差异不显著,仅在第24天显著低于对照组。处理组叶片的果糖含量均高于对照组,特别是在第24天为对照组的1.81倍,差异显著。叶片葡萄糖含量均呈先升高后降低的趋势,可溶性糖总含量则呈波动的变化趋势,对照组叶片葡萄糖含量和可溶性糖总含量总体上高于处理组,但差异不显著。研究结果显示:用秸秆浸提液漂浮栽培,虽然不结球白菜的生长量(即产量)有所减少,但相关的品质指标变化不大,对果糖合成和积累还有一定的促进作用,因而,此种秸秆浸提液可用于栽培商品不结球白菜。     

Chemical composition and antimicrobial activity of the essential oil of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica)

The chemical composition and the antimicrobial activity of the essential oil isolated from the needles of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica) from Croatia were investigated. The chemical composition of the essential oil was determined by GC and GC/MS analyses, and the main compounds identified were α-pinene, β-pinene, germacrene D, and β-caryophyllene. Disc-diffusion and broth-microdilution assays were used for the in vitro antimicrobial screening. The Dalmatian black pine essential oil exhibited a great potential of antibacterial activity against Gram-positive bacteria (MIC=0.03-0.50% (v/v)) and a less pronounced activity against Gram-negative bacteria (MIC=0.12-3.2% (v/v)). The volatile compounds also inhibited the growth of all fungi tested, including yeast.