The placement, recovery, and loss of scatter hoards by eastern chipmunks,Tamias striatus

Although eastern chipmunks typically larder hoard food in theirburrows, some scatter hoarding occurs, especially by newly emergedjuveniles and by females with young. To examine patterns ofscatter hoard placement and their adaptive significance, weused standard food provisioning tests followed by continuousmonitoring to determine the longevity and fate of scatter hoards.Longevity of scatter hoards was low (median 74 min) and pilferagewas high (46%). Chipmunks placed scatter hoards away from thepatch, closer to their burrow and within the defended area ofprimary use. Scatter hoard placement was affected by the numberof competitors at the patch. However, juveniles and femaleswith young differed slightly in their responses. competitorsthat approached scatteihoards were sometimes chased away bythe scatter hoard's owner, and the scatter hoard was moved toanother location by the owner. Females with young recoveredtheir largest scatter hoards first, but there was little additionalpattern in scatter hoard recovery. An experiment using simulatedscatter hoards showed that scatter hoards farther from a patchof food lasted longer and that disturbing and marking scatterhoards reduced their longevity. These observations indicate:(1) that scatter hoard placement is more related to avoidingpilferage of completed caches than to rapidly sequestering fooditems from an ephemeral patch and (2) that optimal cache distributionmay be affected by the cache-defense ability of individuals,by the relationship between competitor density and cache securitynear the patch, and by the territorial behavior of neighboringconspecifics.     

Molecular integrity of monoclonal antibodies produced by hybridoma cells in batch culture and in continuous-flow culture with integrated product recovery

The molecular integrity of monoclonal antibodies (MCAB) produced by murine hybridoma cell line TB/C3 was studied in batch and continuous-flow cultures. In batch culture, one band of MCAB was detected initially by Western blotting of sodium dodecyl sulfate (SDS)-polyacrylamide gels run under unreduced conditions, but heterogenous MCAB bands appeared as the culture aged. The latter were due to the degradation of MCAB by proteases active at the neutral pH of the culture. The deleterious effect of proteases was minimized in the continuous-flow cultures which were integrated for product recovery. The MCAB of high quality was purified over 26 days from a culture grown at a dilution rate of 0.025 h(-1) (experiment 1). However, at a lower dilution rate of 0.015 h(-1) (experiment 2), the integrity of MCAB was compromised after the initial 13 days of culture. This was shown to be due to the variation in the carbohydrate content of MCAB produced, as judged by the increased sialylation of heavy chains and the varied reactivity of MCAB with lectins (Maackia amurensis agglutinin, Galanthus nivalis agglutinin, and Datura stramonium agglutinin) as the age of the culture increased. The concentration of the purified MCAB samples by enzyme-linked immunosorbent assay (ELISA) (used normally) was usually higher than that estimated by absorbance at 280 nm. Best correlation between the two methods (ELISA-280 nm ratio of 1.02-1.25) was obtained with experiment 1 samples. This ratio increased in experiment 2 and batch culture samples as the heterogeneity of MCAB produced increased, being 1.03-2.94 and 2.53-4.62, respectively. Therefore, ELISA overestimated MCAB concentration when the molecular integrity of the latter was compromised. The ELISA-A(280) nm ratio might hence provide a useful indicator for assessing the quality of MCAB produced. Comparison of SDS-polyacrylamide gels stained with Coomassie Brilliant Blue R and silver showed that the former correlated better with the MCAB activity stain, whereas the silver stained both the protein- and carbohydrate-rich components. Comparison of the patterns produced with these two stains might therefore offer another parameter to monitor the overall integrity of MCAB produced. Finally, the data presented have important implications on the validity of using long-term and intensive cultures for generating MCAB because such cultures would be subjected to the additive effects reported for batch and continuous modes of growth. (c) 1993 John Wiley & Sons, Inc.     

Emulsion liquid membrane extraction of lactic acid from aqueous solutions and fermentation broth

Studies on the batch extraction of lactic acid using an emulsion liquid membrane system are reported. The membrane phase consists of the tertiary amine carrier Alamine 336 and the surfactant Span 80 dissolved in n-heptane/paraffin and aqueous solutions of sodium carbonate in the internal phase. The effects of internal phase reagent, extraction temperature, and initial external phase pH on the extraction efficiency and the emulsion swelling are examined. A statistical factorial experiment on extraction from clarified lactic acid fermentation broth was carried out to obtain knowledge of the performance of the extraction system from a broth. The extraction efficiency from the fermentation broth is found to be lower as compared to aqueous solutions of pure lactic acid. The effect of pH and the presence of other ionic species on selectivity are discussed. (c) 1993 John Wiley & Sons, Inc.     

Development of a recovery and recycle process for a pseudomonas lipase used for large-scale enzymatic synthesis

Enzymes are potential catalysts for a wide range of large-scale chemical synthesis steps, particularly when the creation of a specific chiral center is desired. The efficient recycling of the enzyme catalyst and the removal of carryover impurities were crucial factors in the improvement of a stereoselective ester hydrolysis step used in the synthesis of a selective leukotriene antagonist. In this enzymatic reaction step, the substrate and product were both largely insoluble, while the enzyme was soluble in the aqueous reaction mixture. Microfiltration and ultrafiltration of the slurry reaction mother liquor indicated near 100% enzyme protein recovery, while activity recovery was about 70% to 80%. These activity losses might be accounted for by enzyme degradation (1 to 2 mg/L . h) during the 40-hour reaction period. Dissolved impurities, principally a diacid byproduct, in the enzyme recycling stream were reduced 60% to 70% by either lowering the solution pH to 4.0 or raising the solution ionic strength to 1 M. (c) 1993 John Wiley & Sons, Inc.     

脂肪酶水解植物油的研究

本文报导了薄层层析法及高压液相色谱法定性定量地测定植物油甘油酯的组成,对不同来源的脂肪酶对植物油的水解进行了研究。实验结果表明,不同来源的脂肪酶对植物油(橄榄油)的水解性不同,同一脂肪酶水解不同种类的植物油,脂肪酶的水解率也不同,脂肪酶水解植物油有最适pH和最适温度。     

Seagrass ecosystem multifunctionality under the rise of a flagship marine megaherbivore

Large grazers (megaherbivores) have a profound impact on ecosystem functioning. However, how ecosystem multifunctionality is affected by changes in megaherbivore populations remains poorly understood. Understanding the total impact on ecosystem multifunctionality requires an integrative ecosystem approach, which is especially challenging to obtain in marine systems. We assessed the effects of experimentally simulated grazing intensity scenarios on ecosystem functions and multifunctionality in a tropical Caribbean seagrass ecosystem. As a model, we selected a key marine megaherbivore, the green turtle, whose ecological role is rapidly unfolding in numerous foraging areas where populations are recovering through conservation after centuries of decline, with an increase in recorded overgrazing episodes. To quantify the effects, we employed a novel integrated index of seagrass ecosystem multifunctionality based upon multiple, well-recognized measures of seagrass ecosystem functions that reflect ecosystem services. Experiments revealed that intermediate turtle grazing resulted in the highest rates of nutrient cycling and carbon storage, while sediment stabilization, decomposition rates, epifauna richness, and fish biomass are highest in the absence of turtle grazing. In contrast, intense grazing resulted in disproportionally large effects on ecosystem functions and a collapse of multifunctionality. These results imply that (i) the return of a megaherbivore can exert strong effects on coastal ecosystem functions and multifunctionality, (ii) conservation efforts that are skewed toward megaherbivores, but ignore their key drivers like predators or habitat, will likely result in overgrazing-induced loss of multifunctionality, and (iii) the multifunctionality index shows great potential as a quantitative tool to assess ecosystem performance. Considerable and rapid alterations in megaherbivore abundance (both through extinction and conservation) cause an imbalance in ecosystem functioning and substantially alter or even compromise ecosystem services that help to negate global change effects. An integrative ecosystem approach in environmental management is urgently required to protect and enhance ecosystem multifunctionality.     

兴安薄荷挥发油的成分

兴安薄荷（Mentha dahurica Fisch.ex Benth.）为唇形科薄荷属（Mentha L.）多年生草本植物,产于我国黑龙江、吉林、内蒙古东北部。俄罗斯远东地区以及日本北方也有分布。在我国东北有作中药薄荷入药的。其化学成分研究甚少,仅俄国Pulatova报道其含有香豆素类成分。为开发利用我国薄荷植物资源,作者对全国薄荷属植物进行了野外调查,并对其资源、生物学性状、孢粉学和化学等进行了较系统的研究,现仅就兴安薄荷挥发油中化学成分分析结果作一报道。     

石菖蒲中一新倍半萜

石菖蒲（Acorus gramineus Soland）的精油经GC/MS/DS检测,硅胶加压柱层分离,得到一新的倍半萜,其在精油中的含量达60.30％,通过波谱方法确定了结构,并命名为石菖蒲酮（gramenone）。     

Fire affects wood formation dynamics and ecophysiology of Pinus pinaster Aiton growing in a dry Mediterranean area

The increase in frequency and intensity of wildfires is seriously affecting forest ecosystems, especially in drought-prone areas. Trees’ recovery after fire is related to direct tree damage and is influenced by climate conditions, such as warm temperature and water shortage. In this study, we evaluate the post-fire effects on a Pinus pinaster Aiton forest growing in a hot and dry area of the Mediterranean region by comparing burned trees with severe crown reduction against unburned and not-defoliated trees. Inter-annual analyses of dendrochronology and stable isotopes in tree rings were combined with xylogenesis monitoring to investigate the effects of fire on tree growth, ecophysiological processes and wood formation. Tree-ring and isotope data showed a growth reduction and a decrease in photosynthetic activity in the burned trees, compared to control individuals, in the three years after fire. Further, the monitoring of cambial activity demonstrated a negative influence of warm and dry periods on wood formation, low xylem production, a delay in phenology and a reduction in xylem plasticity in burned trees. Our findings suggest that substantial photosynthetic limitations caused by crown defoliation and recurrent drought events could lead to severe growth decrease and reduction of trees ability to regain the pre-disturbance productivity rates.     

Selected factors limiting the microbial degradation of recalcitrant compounds

Summary The focus of this review is to examine some of the reasons biodegradation may not take place in the environment even though its occurrence in the laboratory has been demonstrated. Some approaches for dealing with chemical persistence will be discussed. In addition, the potential of bioremediation as an in situ clean-up technology will be considered.