中国北方上新世降温事件及其对温度纬度梯度变化的影响

西伯利亚地台的新元古代到早寒武世间的钙藻化石特别丰富,为研究钙藻化石的发育历史提供了模式。在几次演化事件背景下记录了演化的两次转折,其中一个是藻类的普遍钙化,还有一个是Botomian晚期到Toyonian早期之间在西伯利亚地台缺失钙藻化石记录,而在其它地区包括西伯利亚地台的边缘(Altay—Sayan地区),钙藻的丰度却达到了最大。     

Function of calcium phosphate renal concrements in extant Nautilus: a paradigm for Cambrian-relict short-term mineral reserve equivalent to vertebrate bone

Renal uroliths (concrements) of calcium phosphate have long been known to exist in both growing and mature (non-growing) Nautilus specimens, but to date no evidence-based explanation for their existence has been available. The currently favored speculation is that they function as a calcium reserve for shell and septal calcification. Here we present new observational and experimental data that are consistent with the hypothesis that they serve as a mineral/ion reserve, allowing short-term (<1 day) addition of ionized calcium and phosphorus to blood and other body fluids, in a way analogous to that of vertebrate bone. In both in-ocean experiments and during long-term observation of captive nautiluses, concrements disappear during two different, energy-intensive activities involving removal of anions and cations from newly secreted cameral liquid in the chamber formation cycle, and during dives to depths requiring high osmotic pressures within the canaliculi of the siphuncular epithelium to keep previously emptied chambers from flooding due to suddenly increased ambient hydrostatic pressure. New concrements reappear at other points in the chamber formation cycle and when normal living depth is restored. The use of concrements as an ion reserve and the Cambrian ancestry of nautiloids indicate that Nautilus may exemplify a solution to the problem of energy supply in newly evolved swimmers of the Cambrian radiation independent of that seen in fish.     

Chemistry and structure of skeletal growth rings in the black coral Antipathes fiordensis (Cnidaria,Antipatharia)

The skeleton of the black coral Antipathes fiordensis is a laminar structure displaying major and minor growth rings. The skeleton is composed primarily of protein and chitin organized into successive microlayers. Each microlayer is tightly bound to the next by an organic cement that is periodically opaque in section, and occurs as clusters throughout the skeleton. In contrast, the skeletal microlayers themselves are never opaque. The apposition of multiple, opaque cement lines between skeletal layers is primarily responsible for the growth ring pattern.     

Response of epiphytic algae to nutrient loading and fish density in a shallow lake: a mesocosm experiment

Studies on the effect of eutrophication on the ecology of shallow lakes, usually pay scant attention to changes within the epiphytic algal community, though the contribution of this to the ecosystem dynamics is transcendental. In order to test the influence of nutrient loadings and fish densities in the structure of algal epiphyton in a shallow lake, an experiment was performed using in situ mesocosms. Nutrient additions were related to significant decreases in the total epiphyton biovolume and that of bacillariophyceans and zygnematophyceans, but with increases in the abundance of cyanobacteria. The different response of algal groups at the higher nutrient concentrations (increases or decreases in their abundance and/or biovolume) can be related to their ecophysiological constraints such as different resistance to toxicant ammonium accumulation. Plant-associated macroinvertebrates numbers were positively correlated with total numbers of epiphyton. The presence of planktivorous fish enhanced the abundance and biovolume of all algal groups, except cyanobacteria. Fishes enhanced the abundance of plant-associated animals and of total epiphyton. Fish indirect effects (e.g., nutrients release) and their dietary particularities were among the factors that together with nutrients influenced epiphyton growth. The role of indirect effects of fishes and the importance of their dietary particularities are stressed as key factors to understand the processes controlling epiphyton ecology and the food web structure of shallow lakes. Handling editor: D. Ryder.     

澄黄滨珊瑚、大管孔珊瑚和丛生盔形珊瑚排卵前后小穗生长特征

澄黄滨珊瑚、大管孔珊瑚和丛生盔形珊瑚排卵前后分别采集珊瑚小穗,在实验室条件下进行为期60 d的养殖,观察其生长特性,结果表明:3种珊瑚排卵前后骨骼密度变化在1.541—2.137 g/cm3之间,差异不显著。3种珊瑚小穗的生长率表现出相对一致的变化趋势,同一规格珊瑚小穗排卵前期生长率明显高于排卵后期;同一时期大规格珊瑚小穗生长率明显高于小规格珊瑚小穗,而且养殖中后期生长较快,养殖前期生长较慢,差异显著(P0.05)。澄黄滨珊瑚小穗边缘组织延伸度排卵后期大于排卵前期,大管孔珊瑚小穗边缘组织延伸度排卵前期大于排卵后期,以上两种珊瑚的小规格珊瑚小穗与大规格珊瑚小穗组织延伸度相当。随着养殖时间的持续,丛生盔形珊瑚小穗螅体增殖速率加快,各养殖阶段螅体数差异显著(P0.05),珊瑚小穗规格和养殖季节对其小穗螅体增殖数量没有显著影响。3种珊瑚小穗生长指标间多呈显著正相关,仅大管孔珊瑚小穗初始直径、初始重量与组织延伸度间,以及丛生盔形珊瑚小穗初始重量与初始螅体数量、生长率间相关性不明显。     

Do reef corals age?

Hydra is emerging as a model organism for studies of ageing in early metazoan animals, but reef corals offer an equally ancient evolutionary perspective as well as several advantages, not least being the hard exoskeleton which provides a rich fossil record as well as a record of growth and means of ageing of individual coral polyps. Reef corals are also widely regarded as potentially immortal at the level of the asexual lineage and are assumed not to undergo an intrinsic ageing process. However, putative molecular indicators of ageing have recently been detected in reef corals. While many of the large massive coral species attain considerable ages (>600 years) there are other much shorter‐lived species where older members of some populations show catastrophic mortality, compared to juveniles, under environmental stress. Other studies suggestive of ageing include those demonstrating decreased reproduction, increased susceptibility to oxidative stress and disease, reduced regeneration potential and declining growth rate in mature colonies. This review aims to promote interest and research in reef coral ageing, both as a useful model for the early evolution of ageing and as a factor in studies of ecological impacts on reef systems in light of the enhanced effects of environmental stress on ageing in other organisms.     

Bigger? Fatter? Or is faster growth better? Considerations on condition in larval and juvenile coral-reef fish

Abstract Analyses of condition data are conspicuous by their paucity in the extensive tropical reef-fish literature. Researchers typically quantify abundance at settlement, with little regard for the demonstrably variable quality of newly settled fishes. Condition may be functionally classified by indices of growth (e.g. the RNA-DNA index or peripheral growth increments of the otolith), starvation (e.g. height of midgut mucosal cells), storage (e.g. lipid content), or morphometry (e.g. dry weight/length’), all of which are variably correlated with each other. At present all indices are species-, stage-, technique- and therefore often investigation-specific, as laboratory-reared larvae for calibrating field-collected condition indices are often specific to the rearing procedure. RNA indices are particularly appropriate for estimating larval condition. In pelagic juveniles, or in recently settled juveniles, the width of peripheral growth increments of the otolith estimates average growth rate in length or dry weight during the previous few days, which discerns increasing from decreasing condition. Increment width changes in otoliths are particularly responsive to starvation events, and are correlated with RNA indices. Growth indices have great potential for determining which individuals were growing faster, thereby reducing their pelagic duration, and thus increasing their survival potential. The recent debate regarding whether bigger larvae have better survival could be re-addressed, by determining if larvae with faster growth indices have relatively enhanced survival.     

Age Structure and Growth of the Dusky Damselfish, Stegastes Fuscus, From Tamandaré Reefs, Pernambuco, Brazil

Age structure and growth of Stegastes fuscus were investigated during the present study. Individuals were collected monthly by divers using nets and spears in the reefs off Tamandaré, Pernambuco, Brazil. Otoliths were removed from 346 individuals and sectioned transversally to determine individual age. Otolith sections showed a clear pattern of opaque and translucent bands. Opaque bands were counted and initially attributed to the age of individual fish. To determine the periodicity of band formation, a validation experiment was performed, in which individuals (n = 8) were injected with tetracycline (50mgkg^-1) and kept in the laboratory for periods of three months to one year. Results of the validation experiment showed that one opaque band is deposited per year. The age of individuals collected from January to December 1995 ranged between 0 and 15 years. Analysis of margins of monthly collected individuals suggested that opaque bands are deposited during the dry season, between September and March. Readings of tetracycline-marked otoliths corroborated these results. The length-at-age curve yielded a growth constant (K) of 0.19y^-1. The high variability of the length-at-age data indicated high variability in individual growth. Length–frequency data were also used to obtain growth parameters. The growth constant, as determined with these data was 0.6y^-1 and differed markedly from K values determined from length-at-age data. It was concluded that length-frequency data are not suitable to determine growth of this species. The present study showed that otoliths are a reliable structure for aging S. fuscus, which showed to be a relatively long-lived and slow-growing tropical reef species.     

猪表皮生长因子在植物乳杆菌中的表达及其活性检测

为获得一株高效表达猪表皮生长因子(p EGF)的重组植物乳杆菌,并检测其生物活性,从仔猪肠道内容物中分离植物乳杆菌,选择其中生物活性最强的一株(Lp-1)为宿主。以商品化乳杆菌表达载体p IAβ8为骨架,干酪乳杆菌超强组成型启动子SCP、M6前体蛋白信号肽SP、猪表皮生长因子p EGF等为元件,构建表达p EGF的植物乳杆菌重组表达载体p SCPSE。用电转化方法 (2.0 k V,2 000?,25μF,4.0 ms)将重组载体p SCPSE转化入宿主菌Lp-1中获得重组植物乳杆菌Lp-p SCPSE。以Tricine-SDS-PAGE法和p EGF ELISA特异性检测试剂盒检测目的蛋白的表达;用培养12 h的阳性转化子菌体给刚断奶的BALB/c小鼠灌胃,2次/d,连续10 d,以断奶小鼠的体重、肠绒毛长度和隐窝深度的变化为指标,检测目的蛋白的生物活性。Tricine-SDS-PAGE检测和小鼠实验结果显示,重组植物乳杆菌的培养上清中出现6 k Da左右p EGF的特异性条带,且表达p EGF的重组植物乳杆菌能显著增加(P0.05)断奶小鼠的体重、肠绒毛高度和肠隐窝深度。结果表明,p EGF在植物乳杆菌中成功表达,且具有良好的生物学活性。     

Reassessment of the mode of life of Pagetia Walcott, 1916 (Trilobita: Eodiscidae) based on a cluster of intact exuviae from the Kaili Formation (Cambrian) of Guizhou, China

Pagetia is the most abundant trilobite in the Kaili Formation (lower to middle Cambrian). During the course of studying the museum collections of Kaili trilobites ( n  > 1000), a cluster containing 22 pagetiid individuals at various growth stages is noted. Specimens record the growth range from the degree 0 meraspid to late holaspid phases. Based on the relative completeness of the moults except for missing free cheeks, these specimens are interpreted as intact exuviae that had undergone minimal transport prior to burial. If Kaili pagetiids had pelagic or planktonic living habits as previously suggested, it would be difficult to explain the presence of intact exuviae in clusters. Therefore, Kaili pagetiids are interpreted here as having a benthic mode of life after the onset of the meraspid phase.