黄颡鱼黑色素细胞原代培养及迁移相关基因克隆分析

黑素皮质素受体-1(MC1R)在鱼体中对黑色素细胞的分化及迁移起主要的调控作用,而且在神经系统和免疫系统中表现出不同功能。本研究对黄颡鱼表皮黑色素细胞的培养条件进行探索,并在此基础上对MC1R基因进行克隆,为后续研究黄颡鱼黑色素异常的细胞及分子机理研究提供基础。结果表明,黄颡鱼表皮黑色素细胞在27 ℃培养条件下,72 h开始贴壁生长,培养基中添加20 %小牛血清培养效果比添加10%小牛血清好。MC1R基因克隆方面,黄颡鱼MC1R基因全长为936 bp,编码312个氨基酸,与剑尾鱼(Xiphophorus maculates)、孔雀鱼(Poecilia reticulata)、条斑星鲽(Verasper moseri)、海鲈(Dicentrarchus labrax)、大菱鲆(Psetta maxima)等5种鱼类MC1R基因的同源性分别为97%、96%、90%、90%、90%,系统分析结果显示,黄颡鱼MC1R基因在进化树上的位置与黄颡鱼的分类所处位置基本吻合。证明黄颡鱼表皮黑色素细胞原代培养的条件为：27℃,添加20% 小牛血清,所克隆基因为黄颡鱼MC1R基因。     

Effect of the appetite stimulant cyproheptadine on deoxynivalenol ‐ induced reductions in feed consumption and weight gain in the mouse 1

Abstract

Deoxynivalenol (DON, vomitoxin), a Fusarium mycotoxin, is suspected of inducing its anorectic/feed refusal activity through a serotoninergic (5HT) mechanism, possible via 5HT₂‐receptors. In this study the efficiency of cyproheptadine (CYP), a serotonin antagonist and known appetite stimulant, to attenuate the adverse effect of DON was investigated in mice. CYP was administered in the feed for two days before animals began receiving the DON, which was also added to the feed. Both agents were administered concurrently thereafter for a 12‐day period. Dosing levels included various combinations of the two compounds, ranging from 0–16 ppm DON and 0–20 ppm CYP.

Results showed that CYP could effectively offset the reduction in feed intake caused by dietary DON, but only when dose levels were optimized (CYP appeared to have a narrow effective dose range, which was also dependent on the DON concentration). In fact, optimum CYP doses were able to enhance feed intake in DON‐fed mice above control levels, indicating that more than just a direct block of the toxin's effect was occurring. Conversely though, the effect of CYP on weight gain (WG) was ambiguous. At the lower CYP doses (≤ 5 ppm), alone or in combination with the lowest DON level tested (4 ppm), a modest positive effect was noted, but at the higher DON concentrations (≥ 8 ppm) the overall WG generally remained depressed, and tended to be reduced further by increasing doses of CYP.

These results provide additional support that serotoninergic mechanisms probably play a role in mediating DON‐induced reduction in feed intake. Where and how DON actually initiates its anorectic effect, however, has not been resolved.     

Organizational identification: Extending our understanding of social identities through social networks

Although organizational identification is founded on social identity and symbolic interactionist theories, current theories emphasize a social identity whereby organizational members categorize themselves and others based on roles and membership in an organization or work unit. In contrast symbolic interactionism, which resides in interpersonal relationships, is rarely theorized or empirically assessed in studies of organizational identification. We use survey data collected at an academic institution to explore how the strength and structure of an individual's social network both directly influences organizational identification as well as moderates the relation between social identity, or categorical, antecedents and organizational identification. Our results show that the size of an individual's network as well as the interaction between relationship strength and prestige better explain organizational identification than do antecedents based solely on categorization and social comparison processes. Thus networks of relationships, which have been a foundational but much neglected premise and process for organizational identification, are brought back into a theory of organizational identification. Copyright © 2010 John Wiley & Sons, Ltd.     

A Biomimetic Approach to the Detection and Identification of Estrogen Receptor Agonists in Surface Waters Using Semipermeable Membrane Devices (SPMDs) and Bioassay-Directed Chemical Analysis (12 pp)

Goal, Scope and Background Some anthropogenic pollutants posses the capacity to disrupt endogenous control of developmental and reproductive processes in aquatic biota by activating estrogen receptors. Many anthropogenic estrogen receptor agonists (ERAs) are hydrophobic and will therefore readily partition into the abiotic organic carbon phases present in natural waters. This partitioning process effectively reduces the proportion of ERAs readily available for bioconcentration by aquatic biota. Results from some studies have suggested that for many aquatic species, bioconcentration of the freely-dissolved fraction may be the principal route of uptake for hydrophobic pollutants with logarithm n-octanol/water partition coefficient (log Kow) values less than approximately 6.0, which includes the majority of known anthropogenic ERAs. The detection and identification of freely-dissolved readily bioconcentratable ERAs is therefore an important aspect of exposure and risk assessment. However, most studies use conventional techniques to sample total ERA concentrations and in doing so frequently fail to account for bioconcentration of the freely-dissolved fraction. The aim of the current study was to couple the biomimetic sampling properties of semipermeable membrane devices (SPMDs) to a bioassay-directed chemical analysis (BDCA) scheme for the detection and identification of readily bioconcentratable ERAs in surface waters. Methods SPMDs were constructed and deployed at a number of sites in Germany and the UK. Following the dialytic recovery of target compounds and size exclusion chromatographic clean-up, SPMD samples were fractionated using a reverse-phase HPLC method calibrated to provide an estimation of target analyte log Kow. A portion of each HPLC fraction was then subjected to the yeast estrogen screen (YES) to determine estrogenic potential. Results were plotted in the form of 'estrograms' which displayed profiles of estrogenic potential as a function of HPLC retention time (i.e. hydrophobicity) for each of the samples. Where significant activity was elicited in the YES, the remaining portion of the respective active fraction was subjected to GC-MS analysis in an attempt to identify the ERAs present. Results and Discussion Estrograms from each of the field samples showed that readily bioconcentratable ERAs were present at each of the sampling sites. Estimated log Kow values for the various active fractions ranged from 1.92 to 8.63. For some samples, estrogenic potential was associated with a relatively narrow range of log Kow values whilst in others estrogenic potential was more widely distributed across the respective estrograms. ERAs identified in active fractions included some benzophenones, various nonylphenol isomers, benzyl butyl phthalate, dehydroabietic acid, sitosterol, 3-(4-methylbenzylidine)camphor (4-MBC) and 6-acetyl-1,1,2,4,4,7-hexamethyltetralin (AHTN). Other tentatively identified compounds which may have contributed to the observed YES activity included various polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives, methylated benzylphenols, various alkylphenols and dialkylphenols. However, potential ERAs present in some active fractions remain unidentified. Conclusions and Outlook Our results show that SPMD-YES-based BDCA can be used to detect and identify readily bioconcentratable ERAs in surface waters. As such, this biomimetic approach can be employed as an alternative to conventional methodologies to provide investigators with a more environmentally relevant insight into the distribution and identity of ERAs in surface waters. The use of alternative bioassays also has the potential to expand SPMD-based BDCA to include a wide range of toxicological endpoints. Improvements to the analytical methodology used to identify ERAs or other target compounds in active fractions in the current study could greatly enhance the applicability of the methodology to risk assessment and monitoring programmes.     

Microecosystem Analysis of the Structure and Functions of Forest Biogeocenoses

The microecosystem approach and an adequate system of quantitative methods have been used to study the relationship between the chorologic changes in the structure and functions of edificator tree stand and other components of the pine (Pinus sylvestris L.) forest cenoecosystems of the Transural and Northern Turgai regions. Significant correlations of the density of pine undergrowth with the litter thickness; of its growth with root competition, stand closeness, and, to a lower degree, photosynthetically active radiation (PAR); and of the numbers of small mammals and groups of soil mesofauna with herbaceous phytomass have been found. The possibility of the synthesis of population-ecological, synecological, and biogeocenological methods has been demonstrated.     

APPLICATION OF SCS INFILTRATION MODEL1

ABSTRACT: The SCS infiltration model was applied to the Ralston Creek watershed in eastern Iowa. The criteria to determine the various model parameters were revised to obtain a better agreement between the observed and computed total runoffs. A procedure to calibrate the infiltration model is presented. The infiltration model was used in conjunction with an overland flow model to develop flood hydrographs. The results indicate that SCS infiltration model adequately describe the distribution of losses.     

EVALUATION OF INFLOW TO MIRROR LAKE,NEW HAMPSHIRE1

ABSTRACT: Measured stream discharge plus calculated ground water discharge (total measured runoff) were compared with runoff calculated by the unit-runoff method for the two largest watersheds of Mirror Lake for 1981–1983. Runoff calculated by the unit-runoff method, using Hubbard Brook watershed 3 as the index watershed, was greater than the total measured runoff into Mirror Lake during periods of high flow and slightly less than the total measured runoff into Mirror Lake during periods of low flow. Annual calculated unit runoff was 17 to 37 percent greater than total measured runoff. Differences in monthly runoff are far greater, ranging from 0 to greater than 100 percent. For high flows the calculated unit runoff is about 2 times greater than total measured runoff. For low flows the northwest basin of Mirror Lake has the greatest ground water contribution compared to the other two basins. In contrast, Hubbard Brook watershed 3 has the least ground water contribution.     

Mentoring with(in) care: A co‐constructed auto‐ethnography of mutual learning

Research into workplace mentoring is principally focussed on predictors and psychosocial and instrumental outcomes, while there is scarcely any in‐depth research into relational characteristics, outcomes and processes. This article aims to illustrate these relational aspects. It reports a co‐constructed auto‐ethnography of a dyadic mentoring relationship as experienced by mentor and protégé. The co‐constructed narrative illustrates that attentiveness towards each other and a caring attitude, alongside learning‐focussed values, promote a high‐quality mentoring relationship. This relationship is characterised, among other things, by person centredness, care, trust and mutual influence, thereby offering a situation in which mutual learning and growth can occur. Learning develops through and in relation and is enhanced when both planned and unplanned learning takes place. In addition, the narrative makes clear that learning and growth of both those involved are intertwined and interdependent and that mutual learning and growth enrich and strengthen the relationship. It is concluded that the narrative illustrates a number of complex relational processes that are difficult to elucidate in quantitative studies and theoretical constructs. It offers deeper insight into the initiation and improvement of high‐quality mentoring relationships and emphasises the importance of further research into relational processes in mentoring relationships. Copyright © 2015 John Wiley & Sons, Ltd.     

Microfluidic photomechanic infrared receptors in a pyrophilous flat bug

Infrared (IR) receptors are so far known only in boid and crotalid snakes and in three genera of pyrophilous beetles that seek out forest fires. Pyrophilous insects can also be found in other orders, however, so it can be hypothesised that IR receptors also occur in some of these species. We investigated the pyrophilous Australian flat bug Aradus albicornis and found a small number of dome-shaped sensilla (diameter 13 microm) on the prothorax, which have previously not been described. Ultrastructural investigations revealed that the sensilla are characterised by a fluid-filled inner compartment enclosed in a round cuticular shell. The cuticular apparatus is innervated by the dendrite of a ciliary mechanoreceptor, which is fluidically coupled to the inner compartment. Electrophysiological recordings demonstrated that the sensilla respond to brief warming by red laser light or to broadband IR radiation. Depending on the radiation intensity (4.4-549 mW/cm(2) tested, threshold measured as 11.3 mW/cm(2)), first spike latencies varied between 3.4 and 7.5 ms. Thus, our findings demonstrate that A. albicornis most probably possesses photomechanic IR sensilla resembling the metathoracic IR sensilla of buprestid beetles of the genus Melanophila. In the Melanophila sensillum, IR radiation causes thermal expansion of a fluid, which rapidly deforms the dendritic membrane of a mechanosensory cell. The existence of photomechanic IR receptors in both beetles and bugs demonstrates a remarkable convergent evolution towards this particular biophysical transduction mechanism and suggests that it provides selective advantages over other possible solutions.     

Alkaloid tolerance in Manduca sexta and phylogenetically related sphingids (Lepidoptera: Sphingidae)

Summary. Nicotine tolerance is well known for Manduca sexta. It also occurs in several other sphingids of the subfamilies Macroglossinae and Sphinginae. Only members of the subfamily Smerinthinae appear to be more susceptible to nicotine intoxication. Phylogenetic trees have been reconstructed from mitochondrial 16S rDNA and nuclear DNA to map nicotine tolerance.?The nicotine binding site of both α-subunits of nicotinic acetylcholine receptors (nAChR) have been amplified and sequenced. No apparent amino acid substitution can be seen in the putative nicotine binding site of the α-subunits of nAChR from nicotine tolerant and nicotine sensitive sphingids. Thus, a simple target-site modification can be ruled out as a cause for nicotine tolerance. This finding agrees with feeding experiments: larvae of M. sexta and other sphingids of the Macroglossinae and Sphinginae not only tolerated nicotine, but also many other alkaloids that affect neuroreceptors other than acetylcholine receptors (nAChR, mAChR).?Only 10 to 20% of nicotine injected into larvae of nicotine-tolerant taxa could be recovered later as free nicotine, nicotine N-oxide or cotinine, i.e., 80 to 90% must have been converted to polar conjugates or degradation products which are not detectable with the methods applied. Usually more than 98% of the recoverable alkaloids were found in the faeces. Excretion reached a maximum 6 h after injection in tolerant taxa. Larvae of Manduca sexta, which were reared on a nicotine-rich diet, showed higher nicotine degradation and faster nicotine elimination than na?ve larvae. Application of the cytochrome P450 inhibitor SKF 525A (proadifen) reduced the formation of nicotine N-oxide and the rate of alkaloid degradation. Thus, an inducible detoxification mechanism, coupled with a rapid and inducible excretion, appear to be a strategy in Sphingidae that helps them to live on host plants rich in otherwise toxic secondary metabolites. Received 23 March 2001; accepted 4 August 2001.