头孢藻属中国新记录种

头孢藻属(Cephaleuros)是一类寄生性藻,在分类学上位于绿藻门石莼纲橘色藻目橘色藻科。国内对头孢藻属的研究多见于它对经济作物和观赏植物的危害,而分类学研究较缺乏。为了全面系统地了解中国头孢藻属的多样性,于2012-2018年先后在多个省份采集头孢藻属标本60余份,并对其进行了形态分类学研究。结果显示,头孢藻属中国新记录种有6种,分别为:寄生头孢藻(Cephaleuros parasiticus Karsten)、德鲁特头孢藻(Cephaleuros drouetii Thompson&Wujek)、肿毛头孢藻(Cephaleuros tumidae-setae Thompson&Wujek)、散生头孢藻(Cephaleuros diffusus Thompson&Wujek)、宽阔头孢藻(Cephaleuros expansa Thompson&Wujek)、亨宁头孢藻(Cephaleuros henningsii Schmidle),对6个种的形态学特征进行了详细描述,并提供了照片资料。

木薯新发藻斑病在中国的发生调查及病原鉴定

2010～2015年,笔者在对中国木薯主栽区的病害调查中发现了一种新的叶斑病。该病在云南、海南、广西、江西、福建等地区均有发生,生长中后期爆发流行,初步分析低温是该病成灾的关键因子。病原在叶片上形成黄褐色或黑褐色、近圆形、中央灰白色毛毡状的病斑,发病叶片大量脱落,严重影响木薯的长势和产量。对来自不同地区的病样进行显微观察。结果表明：病原在寄主组织上均形成有隔的孢囊梗,单生或丛生,其上着生数个圆形、黄色的孢子囊,表明其为寄生性头孢藻。

Optimal Light Intensity and Nitrogen-to-Phosphorus Ratio for Growth of Nitzschia capitellata Hust.

Objective] The aim was to explore the potential of Nitzschia capitel ata as excel ent baits and bioenergy, and the optimal light intensity and nitrogen-to-phos-phorus （N/P） ratio suitable for its growth were researched as wel . [Method] With light intensity gradient set, Nitzschia capitel ata was cultured with the same nutrients at （25 ±1） ℃ and light cycle at 12 h/d to select optimal light intensity. Then, Nitzschia capitel ata was cultured with the same condition, and nitrogen-to-phospho-rus ratios at 5∶1, 6∶1, 7∶1 and 8∶1. [Result] With light intensity at 3 000 lx, specific growth rate and standing stock achieved the highest at 0.51 d-1 and 7.97×104 cel s/ml. The growth condition with nitrogen-to-phosphorus ratio at 6∶1 was the most suitable for Nitzschia capitel ata growth. [Conclusion] The optimal light intensity and nitrogen-to-phosphorus ratio were 3 000 lx and 6∶1, respectively, for Nitzschia capitel ata.

ENCLOSURE EXPERIMENTS ON AND LACUSTRINE PRACTICE FOR ELIMINATING MICROCYSTIS BLOOM

Microcystis bloom, one of the most objectionable characteristics of eutrophication in tropical and subtropical waters, occurred in Donghu Lake (East Lake) of Wuhan every summer from the 1970s up to 1984, but from 1985 up to now failed to occur there. The cause of its disappearance remained in obscurity until recently. In situ enclosure experiments in the lake for three years showed that the stocking of the filter-feeding silver carp (Hypophthalmichthys molitrix) and big-head carp (Aristichthys nobilis) played a decisive role in eliminating Microcystis bloom from the lake; but that recurrence of the bloom is possible under certain conditions. This paper presents the details and the results of enclosure experiments. The authors’ analysis of fish biomass data obtained by echo-sounding and the fishery production of the lake over the years, revealed that the recurrence of Microcystis bloom can be prevented so long as the combined biomass of silver carp and big-head carp remains at or exceeds 50 g per cubic meter of lakewater, as was the case in the lake’s 1985 fish yield of 1015 t.

Habitat suitability analysis of eelgrass Zostera marina L. in the subtidal zone of Xiaoheishan Island

We present a GIS-based habitat suitability index(HSI) model to identify suitable areas for Zostera marina L. restoration in the subtidal zone of Xiaoheishan Island. The controlling factors in the model,in order of importance,are Secchi depth,sediment composition,water temperature,salinity,current velocity,water depth and nutrient quality. Specific factor piecewise functions have been used to transform parameter values into normalized quality indexes. The weight of each factor was defined using expert knowledge and the analytic hierarchy process(AHP) method. All of the data thus obtained were interpolated using the inverse distance weighted(IDW) interpolation method to create maps for the entire region. In this study,the analysis of habitat suitability in the subtidal zone of Xiaoheishan Island was conducted for four seasons. According to the GIS-based HSI model,the optimal habitat of Z ostera marina L. appears in spring,although habitat remains suitable all year round. On the whole,the optimum site for eelgrass restoration is located in the eastern region,followed by the western and southern regions. We believe that the GIS-based HSI model could be a promising tool to select sites for Z ostera marina L. restoration and could also be applicable in other types of habitat evaluation.

Salinity Tolerance and Genetic Diversity of the Dinoflagellate Oxyrrhis marina

To evaluate the relationship between salinity tolerance and genetic diversity of plankton,we collected a wild species of plankton from Taipingjiao,Qingdao.The fragment of ITS1-5.8S rDNA-ITS2 was extracted and sequenced.The results showed that the plankton belongs to Oxyrrhis marina.The salinity tolerance of O.marina ranges from 4 to 60.Seven selected groups were built up to evaluate salinity tolerance and to assess genetic diversity by RAPD.The salinity tolerance comparison revealed considerable differences among groups:the strains of O.marina in group 4 could survive under salinity from 4 to 32,while the strains selected for salinity 60 died under the salinity lower than 16.Analysis of genetic diversity of the seven groups showed that the mean genetic diversity index value was 0.28,but it was only 0.16 in selected group of 4 and was 0.24 for group 60.The result of AMOVA suggested a significantly positive relationship between the salinity tolerance and genetic diversity of O.marina (P<0.01).This study indicates that consideration of intraspecific genetic divergence in O.marina might be indispensable when using it as a model in the study of salinity tolerance of wild plankton.

Effect of Alexandrium tamarense on three bloom-forming algae

We investigated the allelopathic properties of Alexandrium tamarense(Laboar) Balech on the growth of Prorocentrum donghaiense Lu,Chattonella marina(Subrahmanyan) Hara et Chihara and Heterosigma akashiwo(Hada) Hada in a laboratory experiment.We examined the growth of A.tamarense,C.marina,P.donghaiense and H.Akashiwo in co-cultures and the effect of filtrates from A.tamarense cultures in various growth phases,on the three harmful algal bloom(HAB)-forming algae.In co-cultures with A.tamarense,both C.marina and H.akashiwo were dramatically suppressed at high cell densities;in contrast,the growth of P.donghaiense varied in different inoculative ratios of A.tamarense and P.donghaiense.When the ratio was 1:1(P.donghaiense:A.tamarense),growth of P.donghaiense was inhibited considerably,while the growth of P.donghaiense was almost the same as that of the control when the ratio was 9:1.The growth difference of P.donghaiense,C.marina and H.akashiwo when co-cultured with A.tamarense indicated that the allelopathic effect may be one of the important factors in algal competition and phytoplankton succession involving A.tamarense.In addition,the filtrate from A.tamarense culture had negative impacts on these three HAB algae,and such inhibition varied with different growth phases of A.tamarense in parallel with reported values of PSP toxin content in Alexandrium cells.This implied that PSP toxin was possibly involved in allelopathy of A.tamarense.However,the rapid decomposition and inactivation of PSP toxin above pH7 weakened this possibility.Further studies on the allelochemicals responsible for the allelopathy of A.tamarense need to be carried out in future.

就是不明

reckon 的自行车的锁坏了,于是去买了一把新锁,准备下楼上课时换上,走到楼下才发现锁忘了带下来,无奈上课时间快到了,只好对着楼上的 yama 大喊:"喂,yama,帮我把那个车锁拿下来!""什么?把……厕所拿下来?"你自己不会上来吗?"

永乐宮元代建筑彩画

永乐宫由宫門至重阳殿五座建筑,都保存着彩画。現存元代彩画只有三清殿、純阳殿、重阳殿三座主要的建筑。以三清殿的彩画最为精致,純阳殿次之,重阳殿比較粗劣。在这三座殿里除重阳殿为彻上露明造外,三清、純阳二殿全有天花,殿内的梁架有草栿和明栿之分。在草栿的部分全沒有彩画。

明陵的琉璃砖刻彩画

北京昌平区明代十三陵是我国现在保存的最大的明代建筑群之一,它从明代初年(十五世纪初)的长陵直到明代末年(十七世纪初)的思陵止。