Dissolved humic substances – ecological driving forces from the individual to the ecosystem level?

1. This review focuses on direct and indirect interactions between dissolved humic substances (HS) and freshwater organisms and presents novel opinions and hypotheses on their ecological significance. Despite their abundance in freshwaters, the role of HS is still inadequately understood. These substances have been considered too large to be taken up by freshwater organisms. On the contrary, here we present evidence that dissolved HS are indeed taken up and interact directly and/or indirectly with freshwater organisms. 2. We show that dissolved HS exert a mild chemical stress upon aquatic organisms in many ways; they induce molecular chaperones (stress shock proteins), induce and modulate biotransformation enzymes and modulate (mainly inhibiting) the photosynthetic release of oxygen by freshwater plants. Furthermore, they produce an oxidative stress, which may lead to membrane oxidation. HS modulate the multixenobiotic resistance activity and probably other membrane‐bound pumps. This property may lead to the increased bioaccumulation of xenobiotic chemicals. Furthermore, they can modulate the numbers of offspring in a nematode and feminise fish and amphibians. The ecological consequences of this potential remain obscure at present. HS also have the potential to act as chemical attractants (as shown with a nematode). 3. In some macrophytes and algae we show that HS interfere with photosynthesis and growth. For instance, the presence of HS suppresses cyanobacteria more than eukaryotic algae. By applying a quantitative structure activity relationship approach, we show that quinones in the HS interfere with photosynthetic electron transport. We show that even Phragmites leachate can act as a kind of phytotoxin. HS also have the potential to suppress fungal growth, as shown with the water mould Saprolegnia parasitica and force the fungus to respond by spore production. 4. In very soft, humic freshwaters, such as the Rio Negro, Brazil, HS stimulate the uptake of essential ions, such as Na and Ca, at extremely low pH (3.5–4.0) and prevent the ionoregulatory disturbance induced by acid waters, thereby enabling fish to survive in these environments. 5. We discuss whether or not HS are directly utilised by aquatic microorganisms or via exoenzymes, which may be washed in from the terrestrial catchment. There is accumulating evidence that the quality of the HS controls microbial growth. In total, net‐heterotrophy may result from HS‐mediated suppression of primary production by the quinone structures and/or from HS‐mediated support of microbial growth. As there is also evidence that HS have the potential to support photoautotrophic growth and suppress microbial growth, the opposite community effect could result. Consequently, dissolved organic carbon (DOC) has to be chemically characterised, rather than simply measuring bulk DOC concentration. 6. In sum, dissolved HS interact with freshwater organisms in a variety of ways in unenriched humic lakes. In addition to the well known effects of HS on light regime, for example, and the direct and indirect supply with carbon (energy), other interactions may be much more subtle. For instance, HS may induce internal biochemical stress defence systems and have the potential to cause acclimatisation and even adaptation. We are just at the beginning of understanding these interactions between dissolved HS and freshwater organisms.     

颍上八里河自然保护区鹭卵3种重金属残留分析

2005年5月,采集了淮河地区颍上八里河集群繁殖的夜鹭(Nycticorax nycticorax)和小白鹭(Egrettagarzetta)鸟卵共18枚,用原子吸收法测定了卵壳、内容物中重金属Cd、Pb、Cr的残留量。结果表明,所有卵壳样品中均检出一定水平的Cd、Pb和Cr残留量,夜鹭卵壳中重金属残留量为Pb>Cr>Cd,小白鹭卵壳中重金属残留量为Cr>Pb>Cd,卵壳中Pb和Cr残留量的种间差异都不显著,但Cd的种间差异显著;在2种鹭卵内容物中,Cr都被检出,在夜鹭卵内容物样品中,Pb只被部分检出,Cd在2种鹭卵内容物样品中都没有被检出,3种重金属在内容物中残留量的种间差异都不显著。2种鹭卵壳中Pb和Cd残留量极其显著地高于卵内容物,但Cr的这种残留分布上的差异不显著。本研究进一步证明卵壳可用作重金属污染物的指示物,监测和评价湿地生态系统中重金属的污染状况。     

颍上八里河自然保护区鹭卵p3种重金属残留分析

2005年5月,采集了淮河地区颍上八里河集群繁殖的夜鹭（Nycticorax nycticorax）和小白鹭（Egretta garzetta）鸟卵共18枚,用原子吸收法测定了卵壳、内容物中重金属Cd、Pb、Cr的残留量。结果表明,所有卵壳样品中均检出一定水平的Cd、Pb和Cr残留量,夜鹭卵壳中重金属残留量为Pb〉Cr〉Cd,小白鹭卵壳中重金属残留量为Cr〉Pb〉Cd,卵壳中Pb和Cr残留量的种间差异都不显著,但Cd的种间差异显著;在2种鹭卵内容物中,Cr都被检出,在夜鹭卵内容物样品中,Pb只被部分检出,Cd在2种鹭卵内容物样品中都没有被检出,3种重金属在内容物中残留量的种间差异都不显著。2种鹭卵壳中Pb和Cd残留量极其显著地高于卵内容物,但Cr的这种残留分布上的差异不显著。本研究进一步证明卵壳可用作重金属污染物的指示物,监测和评价湿地生态系统中重金属的污染状况。     

辽宁老铁山雀形目鸟类秋季迁徙初探

2000~2004年秋在辽宁旅顺老铁山自然保护区,通过鸟类环志和直接观察的方法,对该地区雀形目(Passeriformes)鸟类秋季迁徙规律进行了研究。5年共环志11 040只雀形目鸟类,发现8种保护区新记录种。结果表明,鸟类迁徙高峰大都集中在10月中下旬;气候条件与鸟类迁徙关系密切;不同年份优势种及种群数量均不同;鸟类的迁徙具有一定的顺序性和集群现象,但不同种类迁徙的种群大小又有差别;2004年雀形目鸟类的种类和数量都明显少于前4年,略有下降趋势。     

1株裂殖壶菌(Schizochytrium sp.)的分离鉴定

采用松树花粉诱集法从乐清湾红树林分离到一株纯培养物,其特点为：营养菌体为椭圆球形,单核;营养菌体的细胞壁由许多紧压在一起的致密鳞片层构成,在细胞壁不连续处可分辨鳞片;营养菌体形成外质网,它产生于外质网形成体;营养菌体以产生游动孢子行无性繁殖,游动孢子为双鞭毛;无性繁殖过程中形成四分体结构。据此鉴定为裂殖壶菌（Schizochytrium sp．）。     

Interspecific delimitation and phylogenetic origin of Pugionium(Brassicaceae)

Pugionium(Brassicaceae)is a small genus that occurs in central Asian deserts.The interspecific delimitation and taxonomic treatments of this genus are disputed and its phylogenetic origin remains unknown. In the present study,we examined these issues based on morphological and molecular data obtained for the first time.We used statistical methods to examine inter-and intraspecific morphological variations.The results suggest that only two species,namely P.dolabratum and P.cornutum,can be warranted for all examined populations and specimens,whereas three species(P.calcaratum,P.cristatum,and P.pterocarpum)should be incorporated into P. dolabratum.This delimitation was further supported by the molecular data:all populations of P.dolabratum,P. calcaratum,P.cristatum,and P.pterocarpum shared the same internal transcribed spacer genotype,whereas those from P.cornutum had another type.Phylogenetic analyses of Pugionium and representative genera of Brassicaceae based on ndhF sequences suggest that this genus is sister to the genus Megacarpaea,which,together,comprise a well-supported lineage with Farsetia,Lobularia,Iberis,and Ionopsidium,whereas the two other genera that were previously suggested to be closely related to this genus(Isatis and Bunias)were placed in the other lineages.We further discuss the origin of Pugionium and suggest that it probably originated in central Asia when the climate became drier from the late Miocene.     

GFP示踪观察移植瘤原代培养细胞的生长规律

采用GFP稳定表达的细胞系(293-BAC)接种裸鼠形成移植瘤.取肿瘤组织进行原代培养,通过GFP示踪和细胞形态学变化,观察了肿瘤组织中细胞的生长规律.肿瘤细胞释放并生长在组织块附近,向周围空间延伸.种植时散落的薄层组织细胞则直接贴壁生长.生长的鼠源间质细胞占总细胞量的1%～3%,散在或在组织新生肿瘤细胞外围集中生长.原代培养的细胞在传代5代以后,其中的鼠源细胞消失.经过成瘤和传代过程的肿瘤细胞生长性能稳定、来源纯净,是相关研究的好材料.观察到的细胞生长规律可为移植瘤的相关研究提供参考.     

蓝猪耳离体受精初试

用体内-体外方法分离了蓝猪耳精细胞。用酶解和解剖方法分离了其成熟卵细胞。分离的精、卵细胞用电融合介导尝试了体外诱导融合。在合适的渗透压（6％甘露醇）和合适的氯化钙（0．04％CaCl2·2H2O）溶液中,用交流电场为30～35V10-25s使精、卵细胞排队;用直流电场400～600V45-50μs65脉冲穿孔条件可诱导30％的精、卵细胞融合和70％以上的卵细胞之间的融合。尝试了人工合子的单细胞培养但未获成功。诱导蓝猪耳精、卵细胞融合的条件与玉米和水稻不同。     

The laboratory evaluation of repellent effect of camouflage face paint mixed with DEET to Aedes albopictus

参照中华人民共和国国家标准GB/T 17322.10-1998和《军队特需药品研发勤务技术指导原则(试行)》规定的测试方法,测试了避蚊胺和水溶性二氧化钛处理迷彩油(CFP)对白纹伊蚊Aedes albopictus的驱避效果,为研发我军专用的防蚊虫迷彩油提供依据.结果表明:在3种颜色迷彩油中加入DEET后,不影响DEET的驱蚊效果;添加不同浓度DEET对蚊虫的驱避效果差异显著,20％dEET和25％dEET+迷彩油对白纹伊蚊的平均防护时间均达到或超过10h,达到《军队特需药品研发勤务技术指导原则(试行)》规定的标准,15％dEET+迷彩油平均防护时间不足10h,未达《军队特需药品研发勤务技术指导原则(试行)》规定的标准.研究表明:将适量DEET与迷彩油混合涂抹于皮肤可能作为演习或战时的伪装和防蚊的一种有效的综合保护措施.     

宁夏灵武市沟眶象发生特点

系统调查沟眶象Eucryptorrhynchus chinensis(Olivier)在宁夏灵武市的发生情况和特点发现:沟眶象以成虫和幼虫在土壤中越冬,成虫有2个发生高峰期,越冬结束后以成虫越冬的沟眶象出土出现第1个高峰期,以幼虫越冬的沟眶象经化蛹羽化出土出现第2个高峰期;幼虫危害臭椿根部形成的瘤状物可以作为鉴别沟眶象危害的特征;沟眶象幼虫在土壤中垂直分布范围集中在0～45 cm深土层,约占80%;成虫出土孔集中在距臭椿树干基部75 cm范围内,占88%。据此建议土壤施药化学防治沟眶象时,施药深度不宜低于45 cm,施药点距树干基部水平距离不得少于75 cm,且树周各个方向均需施药。每年10月末沟眶象开始"入土"、翌年4月末开始"出土",在沟眶象"入土"结束后但未冻土之前的11中旬和土壤解冻之后但尚未"出土"前的4月中旬,这两个时期土壤施药防治效果较好;防治沟眶象的同时,还应适时采取打孔注药、熏蒸等措施防治臭椿(Ailanthus altissima(Mill.)Swingle)树干内的臭椿沟眶象Eucryptorrhynchus brandti(Harold)。