Electric pulses to prepare feeder cells for sustaining and culturing of undifferentiated embryonic stem cells

Current challenges in embryonic-stem cell (ESC) research include the inability of sustaining and culturing of undifferentiated ESCs over time. Growth-arrested feeder cells are essential to the culture and sustaining of undifferentiated ESCs, and they are currently prepared using gamma-radiation and chemical inactivation. Both techniques have severe limitations. In this study, we developed a new, simple and effective technique (pulsed electric fields, PEFs) to produce viable growth-arrested cells (RTS34st) and used them as high-quality feeder cells to culture and sustain undifferentiated zebrafish ESCs over time. The cells were exposed to 25 sequential 10-ns electric pulses (10nsEPs) of 25, 40 and 150 kV/cm with 1-s pulse interval, or 2 sequential 50-μs electric pulses (50μsEPs) of 2.83, 1.78 and 0.78 kV/cm with 5-s pulse interval, respectively. We found that the cellular effects of PEFs depended directly upon the duration, number and electric field strength of the pulses, showing the feasibility of tuning them to produce various types of growth-arrested cells for culturing undifferentiated ESCs. Both 10nsEPs of 40 kV/cm produced by a 10nsEP generator and 50μsEPs of 1.78 kV/cm provided by inexpensive and widely available conventional electroporators, generated high-quality growth-arrested feeder cells for proliferation of undifferentiated ESCs over time. PEFs can therefore be used to replace radiation and chemical inactivation methods for preparation of growth-arrested feeder cells for advancing ESC research.     

Coccolithus pelagicus, a productivity proxy related to moderate fronts off Western Iberia

The traditional interpretation of Coccolithus pelagicus as a cold water proxy is examined based on its distribution patterns in the water column off the Portuguese coast (using data from eleven cruises) and in Holocene surface sediment samples and Quaternary cores from the same region.Coccolithus pelagicus is common in the Portuguese upwelling system, an area where surface waters are predominantly of subtropical origin. Although revealing an affinity for low temperature upwelled waters, the species was found in waters up to 18°C associated with riverine plume and shelf-break fronts. C. pelagicus seemed to consistently occupy a particular ecological niche, between other phytoplankton groups, related to moderate turbulence conditions combined with nutrient availability. From this behaviour, it is proposed that C. pelagicus can be used as a tracer of the periphery of areas of enhanced productivity.Coccolithus pelagicus preferences for fronts of moderate temperature and salinity gradients are tentatively used to explain particular features of its sedimentary record. The repeated increase of C. pelagicus in thanatocoenoses (surface sediment assemblages) close to three river mouths, on the Portuguese shelf, are interpreted as a positive response to the development of riverine plumes. On the other hand, inconsistencies in the correlation between sea surface cooler-glacial and warmer-interglacial isotope stages and the relative abundance pattern of C. pelagicus during the Late Quaternary, as registered in two Galicia Bank piston cores (42°N), are tentatively explained in terms of shifts in the extent of the outer limit of the local palaeoproductivity belt off the Iberian Peninsula.     

Advantages of social foraging in crab spiders: Groups capture more and larger prey despite the absence of a web

Among group‐living spiders, subsocial representatives in the family of crab spiders (Thomisidae) are a special case, as they build protective communal leaf nests instead of extensive communal capture webs. It could thus be inferred that antipredator benefits (e.g., enhanced protection in larger nests) rather than foraging‐related advantages (e.g., capture of more and larger prey) promote sociality in this family. Nonetheless, subsocial crab spiders do share prey, and if this behaviour does not reflect mere food scramble but has a cooperative character, crab spiders may offer insights into the evolution of social foraging applicable to many other cooperative predators that hunt without traps. Here, we performed a comparative laboratory feeding experiment on three of the four subsocial crab spider species—Australomisidia ergandros, Australomisidia socialis and Xysticus bimaculatus—to determine if crab spiders derive advantages from foraging in groups. In particular, we tested artificially composed groups of five sibling spiderlings vs. single siblings in terms of prey capture success and prey size preference. Across species, groups had higher prey capture success (measured in terms of capture rates and capture latency) and were more likely to attack large, sharable prey—dynamics leading to reduced food competition among group members in favour of living and foraging in groups. Within groups, we further compared prey extraction efficiency among the three applied social foraging tactics: producing, scrounging and feeding alone. In A. ergandros, individuals were exceptionally efficient when using the non‐cooperative scrounger tactic, which entails feeding on the prey provided by others. Thus, our multispecies comparison confirms foraging advantages in maintaining a cooperative lifestyle for crab spiders, but also demonstrates the relevance of research into exploitation of cooperative foraging in this family.     

From grey to green: Efficacy of eco‐engineering solutions for nature‐based coastal defence

Climate change is increasing the threat of erosion and flooding along coastlines globally. Engineering solutions (e.g. seawalls and breakwaters) in response to protecting coastal communities and associated infrastructure are increasingly becoming economically and ecologically unsustainable. This has led to recommendations to create or restore natural habitats, such as sand dunes, saltmarsh, mangroves, seagrass and kelp beds, and coral and shellfish reefs, to provide coastal protection in place of (or to complement) artificial structures. Coastal managers are frequently faced with the problem of an eroding coastline, which requires a decision on what mitigation options are most appropriate to implement. A barrier to uptake of nature‐based coastal defence is stringent evaluation of the effectiveness in comparison to artificial protection structures. Here, we assess the current evidence for the efficacy of nature‐based vs. artificial coastal protection and discuss future research needs. Future projects should evaluate habitats created or restored for coastal defence for cost‐effectiveness in comparison to an artificial structure under the same environmental conditions. Cost‐benefit analyses should take into consideration all ecosystem services provided by nature‐based or artificial structures in addition to coastal protection. Interdisciplinary research among scientists, coastal managers and engineers is required to facilitate the experimental trials needed to test the value of these shoreline protection schemes, in order to support their use as alternatives to artificial structures. This research needs to happen now as our rapidly changing climate requires new and innovative solutions to reduce the vulnerability of coastal communities to an increasingly uncertain future.     

植物园活植物信息管理计算机化的现状及前景

植物园活植物信息管理系统是植物园适应时代和自身发展需要,首先在西方发展起来的一种新的植物园活植物信息管理手段,本文综述了植物园活植物信息管理系统发展的基础和国内外发展的现状,分析了活植物信息计算机化过程中存在的问题及发展前景     

An enemy of your enemy is your friend: Impact of predators on aggregation behavior of gammarids

Predation pressure may affect many aspects of prey behavior, including forming groups and changes in social interactions. We studied the aggregation behavior of competing gammarids Dikerogammarus villosus and Pontogammarus robustoides (Amphipoda, Crustacea) to check whether they modify their preferences for conspecifics or heterospecifics in response to predator (the racer goby Babka gymnotrachelus) kairomones in the presence or absence of stone shelters (alternative protection source). Both species exhibited preferences toward shelters occupied by conspecifics over empty shelters and conspecifics apart from shelters, suggesting that their aggregation depends not only on habitat heterogeneity, but also on their social interactions. Moreover, gammarids in the presence of shelters (safer conditions) preferred conspecifics over heterospecifics, but predator kairomones made them form aggregations irrespective of species. In the predator presence, P. robustoides increased its aggregation level only in the sheltered conditions, whereas D. villosus exhibited this response only in the absence of shelters, suggesting that this behavior can protect it against predators. Therefore, we tested the antipredator effectiveness of D. villosus aggregations by exposing them to fish predation. Gobies foraged most effectively on immobile single gammarids compared to moving and aggregated individuals. Fish also avoided aggregated prey, confirming the protective character of aggregations. We have demonstrated that the predator presence increases aggregation level of prey gammarids and affects their social behavior by reducing antagonistic interactions and avoidance between competing species. This is likely to affect their distribution and functioning in the wild, where predator pressure is a standard situation.     

应用活细胞RNA检测纳米技术检测乳腺上皮细胞MCF-10A及乳腺癌细胞MCF-7中miR-142-3p的表达

传统的核酸检测技术如放射性核素、荧光、化学修饰的探针以及核酸扩增等技术无法检测活细胞中核酸的表达量。而活细胞RNA纳米检测技术和传统的检测技术相比,利用纳米金颗粒为探针能对活细胞进行检测,实验步骤更为简单,可以在自然的、无扩增的条件下观察RNA,这可真实地反应基因表达与表型之间的关系。miRNA是一类非编码RNA,其长度为20～24个碱基,在生命活动中起重要的作用。本文应用活细胞RNA检测纳米技术结合荧光定量PCR分别检测正常的乳腺上皮细胞系及乳腺上皮癌细胞系中内源性miR-142-3p的表达,发现乳腺癌细胞系内源性miR-142-3p的表达显著高于正常乳腺上皮细胞系中miR-142-3p的表达,结果提示miR-142-3p可能在乳腺癌细胞发生发展中起到调控作用。