两种获取鱼类线粒体DNA的方法比较

直接从鱼类组织提取线粒体DNA和先提取基因组DNA再用相应引物PCR扩增所需mtDNA某一区域序列片段是获取鱼类mtDNA切实可行的两种方法。对这两种方法在使用过程中的注意事项、各自的优缺点及应用范围进行了较为细致的比较,为更好地利用mtDNA这一重要分子标记研究鱼类mtDNA的遗传多态提供参考。     

How to obtain individual urine samples from undisturbed marmoset families

An apparatus and a method are described, which allow simultaneous urine collection from all individual members of undisturbed marmoset families. The monkeys have been trained, after leaving their sleeping box, to enter single adjacent compartments where they are rewarded. There the monkeys micturate within minutes and the clean urine runs directly into cryotubes. These simultaneously collected urine samples open up the opportunity for investigation of the relationship between endocrine function and behavioral dynamics within entire marmoset groups. © 1993 Wiley-Liss, Inc.     

How to catch foliage-dwelling spiders (Araneae) in maize fields and their margins: a comparison of two sampling methods

The foliage‐dwelling spider fauna was collected in maize fields and on stinging nettles in adjacent margins in Bavaria, South Germany. Two different sampling methods were evaluated: drop cloth sampling and suction sampling. The overall catch was dominated by juvenile spiders, web‐building spiders, and spiders of the families Theridiidae, Linyphiidae, Tetragnathidae and Araneidae (in decreasing order). Field margins harboured more species than maize fields, whereas the total spider abundance was higher in the maize crop. Web‐building spiders such as Theridiidae and Linyphiidae were prominent in maize by individual numbers. Suction sampling with a small suction device proved to be a more efficient and consistent sampling method for foliage‐dwelling spiders than drop cloth sampling. Density and species richness of foliage‐dwelling spiders in maize was shown to be fairly high, implying that spiders of higher strata may play a more important role in biological control than suspected up to now.     

A comparison between two methods of extracting chlorophyll-a from different phytoplankton samples

Summary A comparison has been made between chlorophyll-a estimations based on the cold acetone extraction procedure and on the hot ethanol extraction method. When comparing the results obtained with both methods a standard deviation of 20% must be taken into account. A correlation between extraction efficiency and phytoplankton species composition could not be found. Although the chlorophyll-a yield in ethanol extracts is not better than that in acetone extracts, there are several advantages in using the ethanol method, particularly the short extraction period and the cheaper procedure.     

Rapid and reliable DNA extraction techniques from trypan-blue-stained mycorrhizal roots: comparison of two methods

Two improved DNA extraction techniques from trypan-blue-stained root fragments were developed and compared for rapid and reliable analyses. In Method A, 1 cm trypan-blue-stained mycorrhizal root fragments were individually isolated, crushed by bead beating, and purified with Chelex-100 (Bio-Rad). In Method B, DNA extraction was carried out using an UltraClean microbial DNA isolation kit (MoBio Laboratories). DNA was extracted from the mycorrhizal roots of four plant species, quantified by UV absorbance, and PCR-amplified with primers specific to arbuscular mycorrhizal fungi. Although PCR inhibitors might still exist when using Method A, appropriate dilution and employment of nested-PCR overcame this problem. Method B removed PCR inhibitors, but sometimes, depending on the mycorrhizal colonization within the root fragments, it also required nested PCR. In conclusion, both methods enabled us to handle many samples in a short time. Method B provided greater reliability and Method A provided better cost performance. Both techniques can be useful for PCR-based applications to identify species and estimate species composition after measuring mycorrhizal colonization rate with trypan blue staining.     

Simple methods to obtain preliminary growth estimates for fishes

Explored were methods to derive preliminary information on growth from other known life history parameters such as maximum size and size and age at first maturity. Use was made of the fact that with asymptotic length known, only one point is needed to determine the general shape of a von Bertalanffy growth curve. An empirical relationship was used to predict asymptotic length from maximum observed length. We used mean size reached at age 1 or 2 or mean age and size at first maturity, as is often provided in the literature, to derive preliminary von Bertalanffy growth curves. Results of this approach were then compared with published growth estimates. We used an empirical relationship to predict length at first maturity from asymptotic length when only the age at first maturity was given in the literature. Temperate fishes usually have restricted spawning periods lasting a few months per year and maturity is typically reached in the first, second, third, or later year, i.e. in steps of 12 months, with larger species maturing later. We used data in FishBase ( http://www.fishbase.org ) to establish typical ranges for age at first maturity and growth performance of temperate fishes as a function of maximum size. We present an approach that uses this framework to derive preliminary growth estimates for species of which only the maximum size is known.     

How to obtain labeled proteins and what to do with them

We review new and established methods for the chemical modification of proteins in living cells and highlight recent applications. The review focuses on tag-mediated protein labeling methods, such as the tetracysteine tag and SNAP-tag, and new developments in this field such as intracellular labeling with lipoic acid ligase. Recent promising advances in the incorporation of unnatural amino acids into proteins are also briefly discussed. We describe new tools using tag-mediated labeling methods including the super-resolution microscopy of tagged proteins, the study of the interactions of proteins and protein domains, the subcellular targeting of synthetic ion sensors, and the generation of new semisynthetic metabolite sensors. We conclude with a view on necessary future developments, with one example being the selective labeling of non-tagged, native proteins in complex protein mixtures.     

A comparison of two methods and different media for isolatingFrankia from Casuarina root nodules

Four species of Casuarina were raised in the glasshouse and inoculated with nodules collected from nine different geographical areas within Australia. Isolations ofFrankia were attempted from 10 of the Casuarina-Frankia nodule combinations using two methods, a nodule dissection and a filtration method. With both techniquesFrankia isolates were obtained from four of the 10Frankia sources. Spores were not observed in sections of nodules from the four sources from whichFrankia was isolated, whereas spores were observed in the remaining six nodule sources. For selected nodule sources a range of isolation media were tried, but no improvement in the isolation success rate was achieved. The effect of host species on ease of isolation was studied. The results obtained suggested it was theFrankia strain and not the host plant species which determined the ease of isolation from Casuarina nodules.     

Detection of low pathogenic avian influenza viruses in wild ducks from Canada: comparison of two sampling methods

Surveillance for avian influenza viruses in wild birds was initiated in Canada in 2005. In 2006, in order to maximize detection of highly pathogenic avian influenza viruses, the sampling protocol used in Canada's Inter-agency Wild Bird Influenza Survey was changed. Instead of collecting a single cloacal swab, as previously done in 2005, cloacal and oropharyngeal swabs were combined in a single vial at collection. In order to compare the two sampling methods, duplicate samples were collected from 798 wild dabbling ducks (tribe Anatini) in Canada between 24 July and 7 September 2006. Low pathogenic avian influenza viruses were detected significantly more often (P<0.0001) in combined oropharyngeal and cloacal samples (261/798, 33%) than in cloacal swabs alone (205/798, 26%). Compared to traditional single cloacal samples, combined samples improved virus detection at minimal additional cost.     

How to efficiently obtain accurate estimates of flower visitation rates by pollinators

Regional declines in insect pollinators have raised concerns about crop pollination. Many pollinator studies use visitation rate (pollinators/time) as a proxy for the quality of crop pollination. Visitation rate estimates are based on observation durations that vary significantly between studies. How observation duration relates to the accuracy of the visitation rate estimate is, however, unknown. We studied this relationship using six day-long observations (06:00 h–19:00 h) in leek-seed production fields (totalling 78 h). We analysed beyond which point in time observing longer did not significantly improve the accuracy of the visitation rate estimate (minimum observation duration). We furthermore explored the relationship between the minimum observation duration and visitation rate, time of day and temperature. We found that the minimum observation duration (mean ± SD: 24 ± 11.9 min) was significantly related to visitation rate, where the observation time required to obtain accurate estimates decreased with increasing visitation rate. Minimum observation duration varied greatly between days and between fields but not within days. Within days, the visitation rates differed significantly only between the hour-intervals 06:00 h–07:00 h (lowest visitation rate) and 09:00 h–11:00 h (highest rate). Minimum observation duration decreased up to around 22 °C beyond which it remained fairly stable. Surprisingly, even after three day-long observations on the same plant we found new pollinator species visiting the flowers, suggesting that species-richness estimates based on plant observations alone probably underestimate true species richness. Because especially between-day variation in visitation rate on single plants can be large, reliable estimates of the pollinator visitation rate during the plant’s flowering time require observations on multiple days. Standardising the number of pollinators rather than the time to observe (standardised pollinator timing approach: time to n-pollinator visits) may provide more consistent accurate assessments of visitation rate, especially for studies that use gradients in visitation rates to examine the contribution of pollinators to crop pollination.     

Making predictions of mangrove deforestation: a comparison of two methods in Kenya

Deforestation of mangroves is of global concern given their importance for carbon storage, biogeochemical cycling and the provision of other ecosystem services, but the links between rates of loss and potential drivers or risk factors are rarely evaluated. Here, we identified key drivers of mangrove loss in Kenya and compared two different approaches to predicting risk. Risk factors tested included various possible predictors of anthropogenic deforestation, related to population, suitability for land use change and accessibility. Two approaches were taken to modelling risk; a quantitative statistical approach and a qualitative categorical ranking approach. A quantitative model linking rates of loss to risk factors was constructed based on generalized least squares regression and using mangrove loss data from 1992 to 2000. Population density, soil type and proximity to roads were the most important predictors. In order to validate this model it was used to generate a map of losses of Kenyan mangroves predicted to have occurred between 2000 and 2010. The qualitative categorical model was constructed using data from the same selection of variables, with the coincidence of different risk factors in particular mangrove areas used in an additive manner to create a relative risk index which was then mapped. Quantitative predictions of loss were significantly correlated with the actual loss of mangroves between 2000 and 2010 and the categorical risk index values were also highly correlated with the quantitative predictions. Hence, in this case the relatively simple categorical modelling approach was of similar predictive value to the more complex quantitative model of mangrove deforestation. The advantages and disadvantages of each approach are discussed, and the implications for mangroves are outlined.     

Microbiological air analysis in dental surgeries: A comparison between two methods

The microbiological quality of indoor air is creating an increasing interest especially as far as places at risk such as hospitals, clinics, medical and odontological surgeries are concerned. Working with the odontologists of our province we have been carrying out a research aimed at preventing cross-infection in odontology. Data obtained from the microbiological analysis of the air in 36 surgeries using S.A.S were discussed during the V National Congress of Aerobiology. During that congress the need of setting a standardized technique of air sampling in indoor environments emerged and two routes have been identified: (1) the gravimetric technique on open plate exposed for an hour close to the dental unit and (2) the use of the volumetric sampler which gives qualitative data expressed as colonies forming units per cubic metre of air. However, both of these techniques present some problems: using the first a loss of micro-organisms has been noticed due to the variability of the air fluxes and the different weight of the biological particles; using the second one the bacterial charge is also undervalued, because of the stress suffered by the bacteria with the use of the volumetric sampler. In the light of these statements we decided to use both in dental surgeries to be able to compare the results obtained. Our project is expected to carry out at least one inspection and the relative sampling (indoor air, water of the dental unit, air of the syringe, disinfectant solution, surface tampons, biological test of sterility) in each dental surgery in the territory of our health Unit, located in Ferrara, Northern Italy.