Glutathione antioxidant status of frozen meat samples

Lipid oxidation is a process, which results in rancidity and deterioration of fats posing a major problem in food industry. Antioxidants are of interest, which presumably protects food from oxidative deterioration during storage. The glutathione antioxidant system of different meat samples were noticed for six months under refrigerated storage. Activity of glutathione reductase (GR) and level of glutathione (GSH) decreased during six months storage in all the four meat samples. The glutathione peroxidase (GSH-Px) and glutathione-S-transferase (GST) activity increased gradually during storage. It seems possible that glutathione antioxidant system protected the meat samples against quality loss during its storage.     

Influence of acorn size and storage duration on moisture content, germination and survival of Quercus petraea (Mattuschka)

This study was conducted to evaluate how acom size (small, medium and large) and acorn storage duration (0, 5 and 17 months) influenced Quercus petraea (Mattuschka) moisture content and germination. Acorn size and storage duration did not significantly affect acorn moisture content, but they significantly affected acorn germination performance. When averaged for three acorn sizes, loss of germination performance occurred after 17 months of storage even when the moisture content did not reduce significantly and remain at the initial level (32.6%). Maximum germination percentage was observed in large and medium size classes before storage (93 and 95%, respectively) and after 5-month storage (94 and 93%, respectively), but after 17-month storage medium acorn size class exhibited the highest germination (68%). Small seed size class exhibited the lowest germination percentage and rate in each acorn storage duration. Acorn size also significantly affected seedling emergence and survival in the nursery and seedling emergence and survival was the lowest in small seed size class (85 and 80%, respectively). Although seedling survival of one-year seedlings in the nursery increased up to large seed size class, maximum survival in nursery conditions was observed in large and medium size classes (89 and 91%, respectively). Thus, acorn size grading in Q. petraea may result in higher germination performance within in a seedbed.     

冷藏技术对发光细菌活性及毒性测试性能的影响

由于发光细菌的在线毒性监测技术受到了细菌生物活性稳定性保持问题的制约,探索一种脱脂牛奶菌悬液冷藏复苏方法,以提高发光细菌活性的保持时间。比较了明亮发光杆菌新鲜菌液冷藏、冻干粉菌悬液冷藏和脱脂牛奶菌悬液冷藏对发光细菌生物活性的影响,同时,比较了不同渗透压调节液对菌悬液急性毒性测试的灵敏度和稳定性的影响。结果表明,质量分数为25%的脱脂牛奶可提高发光细菌生物活性的稳定性,菌悬液冷藏7d后复苏,相对发光率仍可达92%。2%NaCl和10%蔗糖为渗透压调节液时,冷藏至第7天的发光细菌脱脂牛奶菌悬液对重金属毒性测试的灵敏度,与新鲜菌液基本相同,但添加蔗糖降低了其对有机物的测试灵敏度。利用发光细菌脱脂牛奶冷藏菌悬液对Zn~(2+)进行连续7d的毒性测试,EC_(50)的变异系数小于15%,结果稳定性良好。     

Root biomass and carbon storage in oriental spruce and beech stands in Artvin, Turkey

In this study, influence of slope position (south-facing vs. north-facing), species type and sampling time on fine (0-2 mm), small (2-5 mm) and coarse (5-10 mm) root biomass and carbon storage of oriental spruce (Picea orientalis) and oriental beech (Fagus orientalis) were investigated. Mean total root biomass of oriental spruce was 20160 kg ha(-1) in south-facing slopes and 17140 kg ha(-1) in north-facing slopes. Mean total belowground C storage of oriental spruce was 7861 kg ha(-1) in south-facing slopes and 6840 kg ha(-1) in north-facing slopes. Similarly, biomass and C storage of oriental beech were 17190 and 6690 kg ha(-1) in south-facing slopes, and 13260 and 5200 kg ha(-1) in north-facing slopes, respectively. Oriental spruce had significantly higher fine root biomass than did oriental beech in south-facing slopes. Fine root biomass was significantly higher in fall than in spring in south-facing slopes.     

Response of ecological storage and conservation to land use transformation: A case study of a mining town in China

Rapid land use transformation shaped by agriculture, industrialization and population urbanization has a great influence on ecological environment. Based on theory of ecosystem service functions, this study aims at revealing the response of ecological storage and conservation to each unit area of land use transformation. Taking Cishan Town, a mining town in China, as a case study, this paper estimates the “past-present-future” ecological storage impacted by the process, result and possibility of land use transformation. The local land use and industrial distribution show that the active areas of land use transformation are also the areas of concentration of human (industrial) activities. Ecological storage shows the different responses to land use ways. And then this study combines the ecological storage indices with the indices of ecosystem pattern and land condition into the“5A” framework (active state, active degree, active possibility, active balance and active condition) for grading ecological conservation, and then assigns all regions of Cishan Town into different grades through membership functions for complex mapping of ecological conservation. The research results show that the ecological conservation in Cishan goes toward two extreme grades (best grade and worst grade). Uneven and unbalanced land use transformation is the main cause of that. Hence, rational and timely reflection of impact of land use transformation on ecological storage and conservation can assist land use planners and local government in adjusting land use ways and balancing regional ecology and economy.     

Land Use, Lag Times and the Detection of Demographic Change: The Case of the Acorn Woodpecker

Changes in land-use patterns that alter habitat may have a delayed negative effect on animal species occupying that habitat, and thus such effects may not be recognized for years. In Water Canyon, located in the Magdalena Mountains of southcentral New Mexico, we studied a relatively stable population of the cooperatively breeding Acorn Woodpecker ( Melanerpes formicivorus ) from 1975 to 1984. These woodpeckers rely on self-constructed storage sites, or "granary trees," to hold the acorns used during the winter and spring. Most granaries were in dead trunks and limbs of the narrow-leafed cottonwood trees ( Populus angustifolia . Storage sites form the primary basis for differential quality among territories. Groups of woodpeckers with large storage facilities (high-quality territories) have greater annual reproductive success and survival than do pairs or groups with poorly developed storage sites. In the summers of 1994 and 1995 we censused the original study site, which had held 21 territories. Most territories that had contained birds a decade earlier were unoccupied. This drastic decline was correlated with the loss of nearly all large storage facilities because of the collapse of the granary trees. Most neighboring territories with lesser storage facilities also were vacant. The lack of production of new, high-quality granaries for the period 1975–1995 probably is due inpart to the age structure of the cottonwood trees, which is distinctly bimodal: nearly all trees are either very young or old. There are now fewer old, partly dead trees that could provide granary sites. The scarcity of middle-aged trees reflects a period of intensive cattle grazing in Water Canyon, during which time production of young cottonwoods was suppressed.     

ABA对米槠和格氏栲种子发育的影响

采用酶联免疫分析法（ＥＬＩＳＡ） 提取和测定米槠和格氏栲发育过程中果实内ＡＢＡ含量,并用不同浓度ＡＢＡ喂养,测定果实不同发育期对外源ＡＢＡ的敏感性．用放射性同位素法测定ＡＢＡ对贮藏蛋白质的积累作用,结果表明：在米槠和格氏栲种子发育过程中内源ＡＢＡ 含量逐渐上升,两者均在１０ 月５ 日达到峰值,米槠为１６４８ ｎｇｇ,格氏栲为１ ４６８ ｎｇｇ,随后ＡＢＡ含量均逐渐下降．果实成熟采收时,ｃ（ＡＢＡ） 仅为高峰时的１９．随着果实的发育对外加ＡＢＡ的敏感性逐渐变小,ｃ（ＡＢＡ）＝１０－４ ｍｏｌＬ－１ 可以完全抑制１０ 月２５ 日（ 米槠） 和１０ 月１５ 日（ 格氏栲） 前种子发芽,但对完全成熟的种子ｃ（ＡＢＡ）＝１０－２ ｍｏｌＬ－１ 亦不能抑制发芽．ＡＢＡ 对成熟前期胚的贮藏蛋白质合成无影响,但能促进成熟中后期胚的贮藏蛋白质的积累作用,ＡＢＡ维持米槠和格氏栲贮藏蛋白质合成和积累作用表现在转录水平上．     

Effects of different mowing frequencies on soil carbon and nitrogen changes in leymus chinensis steppe of Hulun Buir北大核心CSCD

Mowing is the main management of Hulun Buir grasslands in Inner Mongolia; therefore, understanding the changes of soil organic carbon (SOC), total nitrogen (TN), and carbon sequestration under different mowing frequencies will provide an important scientific basis for grassland carbon sink management in Inner Mongolia. Three treatment plots were devised in the study area, including enclosed sample (Y), mowing every other year (2G), and mowing once a year (1G), where SOC, TN content and storage were investigated. The results showed that with increased mowing frequency, the SOC and TN content showed a decreasing trend in the 0-30 cm depth soil layer. The SOC and TN content were different in each soil layer, which decreased gradually with increasing soil depth in Y and 2G plots, whereas increased gradually in 1G plots. The soil carbon storage was significantly correlated with the soil nitrogen storage, and both showed a significant linear decrease with increased mowing frequency, which showed as carbon and nitrogen loss. In 2G plots, the soil carbon storage decreased by 17.1% and soil nitrogen storage decreased by 20.8%. In 1G plots, the soil carbon storage decreased by 21.6% and soil nitrogen storage decreased by 29.3%. The results showed that the change of soil carbon and nitrogen was sensitive to mowing frequency for the Hulun Buir grassland. It is possible to reduce the loss of carbon and nitrogen by reasonably controlling mowing frequency, and the sustainable use of grassland could be achieved with appropriate fertilization. Keywords. © 2018 Science Press. All rights reserved.     

Energy and environmental applications of carbon nanotubes

Energy and environment are major global issues inducing environmental pollution problems. Energy generation from conventional fossil fuels has been identified as the main culprit of environmental quality degradation and environmental pollution. In order to address these issues, nanotechnology plays an essential role in revolutionizing the device applications for energy conversion and storage, environmental monitoring, as well as green engineering of environmental friendly materials. Carbon nanotubes and their hybrid nanocomposites have received immense research attention for their potential applications in various fields due to their unique structural, electronic and mechanical properties. Here, we review the applications of carbon nanotubes (1) in energy conversion and storage such as in solar cells, fuel cells, hydrogen storage, lithium ion batteries and electrochemical supercapacitors, (2) in environmental monitoring and wastewater treatment for the detection and removal of gas pollutants, pathogens, dyes, heavy metals and pesticides and (3) in green nanocomposite design. Integration of carbon nanotubes in solar and fuel cells has increased the energy conversion efficiency of these energy conversion applications, which serve as the future sustainable energy sources. Carbon nanotubes doped with metal hydrides show high hydrogen storage capacity of around 6?wt% as a potential hydrogen storage medium. Carbon nanotubes nanocomposites have exhibited high energy capacity in lithium ion batteries and high specific capacitance in electrochemical supercapacitors, in addition to excellent cycle stability. High sensitivity and selectivity towards the detection of environmental pollutants are demonstrated by carbon nanotubes based sensors, as well as the anticipated potentials of carbon nanotubes as adsorbent to remove environmental pollutants, which show high adsorption capacity and good regeneration capability. Carbon nanotubes are employed as reinforcement material in green nanocomposites, which is advantageous in supplying the desired properties, in addition to the biodegradability. This article presents an overview of the advantages imparted by carbon nanotubes in electrochemical devices of energy applications and green nanocomposites, as well as nanosensor and adsorbent for environmental protection.     

Influence of ozone on the sampling and storage of volatile organic compounds in canisters

A dynamic dilution system was used for the study of the influence of ozone on the sampling and storage of volatile organic compounds (VOCs) at 0, 4, 7 and 14 days in “TO-Can” canisters at two ozone concentrations, 60 and 150 ppbv. Among the 31 ozone precursors VOCs, a representative mixture containing five alkenes, five aromatics, acetylene and 1,3 butadiene was selected using the Clausius–Clapeyron equation. Here, we demonstrate that the presence of ozone have no influence on the concentrations of VOCs after 14 days storage period and consequently no problem of representativity of the sampling appears after 14 days of storage. The main explanation is the degradation of ozone in contact with deactivated walls of canisters.     

Carbohydrate storage and light requirements of tropical moist and dry forest tree species

In many plant communities, there is a negative interspecific correlation between relative growth rates and survival of juveniles. This negative correlation is most likely caused by a trade-off between carbon allocation to growth vs. allocation to defense and storage. Nonstructural carbohydrates (NSC) stored in stems allow plants to overcome periods of stress and should enhance survival. In order to assess how species differ in carbohydrate storage in relation to juvenile light requirements, growth, and survival, we quantified NSC concentrations and pool sizes in sapling stems of 85 woody species in moist semi-evergreen and dry deciduous tropical forests in the rainy season in Bolivia. Moist forest species averaged higher NSC concentrations than dry forest species. Carbohydrate concentrations and pool sizes decreased with the light requirements of juveniles of the species in the moist forest but not in the dry forest. Combined, these results suggest that storage is especially important for species that regenerate in persistently shady habitats, as in the understory of moist evergreen forests. For moist forest species, sapling survival rates increased with NSC concentrations and pool sizes while growth rates declined with the NSC concentrations and pool sizes. No relationships were found for dry forest species. Carbon allocation to storage contributes to the growth-survival trade-off through its positive effect on survival. And, a continuum in carbon storage strategies contributes to a continuum in light requirements among species. The link between storage and light requirements is especially strong in moist evergreen forest where species sort out along a light gradient, but disappears in dry deciduous forest where light is a less limiting resource and species sort out along drought and fire gradients.     

Sperm precedence, mating interval, and a novel mechanism of paternity bias in a beetle (Tenebrio molitor L.)

When females mate with more than one male, the ensuing sperm competition leads to the evolution of male mechanisms that skew paternity. Males of the yellow mealworm beetle (Tenebrio molitor) transfer a spermatophore to females during copulation, but sperm release and storage occur later. We investigated how the interval between two matings with different males affects sperm precedence by varying the interval between the copulations so that the second mating was either: (1) before sperm release from the first spermatophore (<5 min); (2) after sperm release but before spermatophore ejection (15–20 min); (3) after spermatophore ejection but before sperm storage (4 h), or (4) after complete sperm storage (24 h). We collected offspring over a period of 2 weeks and determined paternity by protein electrophoresis. There was second-male sperm precedence in all treatments, but when the interval was <5 min, the second male usually (86% of cases) had complete sperm precedence (i.e., P ₂=1). Investigations into the mechanism of second-male sperm precedence during <5-min mating intervals indicate that sperm release from the first spermatophore is inhibited, a phenomenon which has not been previously documented. Received: 31 January 2000 / Revised: 9 June 2000 / Accepted: 26 August 2000     

Ecological correlates of social organization in a communally breeding bird,the acorn woodpecker,Melanerpes formicivorus

Summary Acorn woodpeckers (Melanerpes formicivorus) were studied during the summers of 1976 and 1977 in the Chiricahua Mountains of Arizona to determine the ecological correlates of variations in unit size, storage behavior, and home range. Unit size varied from two to five adults, acorn storage capacity varied from 0 to 5,000 individual holes per unit, and home range size varied from 5.2 to 51.2 ha.There was a consistent but nonsignificant trend for units inhabiting pine-oak woodland to be larger and to maintain more food storage holes than units in oak-juniper or oak woodland. Pine-oak woodland had the highest oak species number, density, and basal area of any community in the study area, and showed the least annual variation in percent of oaks producing acorns during the study. However, pineoak woodland also had the lowest acorn productivity per hectare.More than four times as many oak trees produced acorns in 1977 than in 1976. Following the poor 1976 crop, unit home range size increased so that the mean number of oaks contained per home range size increased more than three and a half times in 1977. The number of woodpecker units containing nonbreeding adults decreased from 90% in 1976 to 20% in 1977. These data suggest that the size and reliability of acorn crops control the composition of acorn woodpecker social units.A comparison of acorn woodpecker population parameters in the Chiricahua Mountains and at the Hastings Reservation, California, was made, using data of MacRoberts and MacRoberts (1976). The California population was significantly more dense and maintained more storage trees and more individual storage holes per unit, but there was no evidence that more California units contained nonbreeding adults than did Chiricahua units.A model is presented that emphasizes the importance of acorn crop reliability as the major determinant of acorn woodpecker social organization (Fig. 2). Annual crop fluctuations affect the winter survival and dispersion of woodpecker units, and the density of the population in the following spring. Bad acorn years will result in decreased saturation of woodpecker nesting habitat by established groups. The model predicts a corresponding decrease in the frequency of units with helpers, as young adults take advantage of opportunities to breed on their own. Longer-term crop reliability determines the benefitcost ratio for establishing and maintaining food storage facilities. The observed geographic variation in storage behavior between California and Arizona populations is suggested to reflect differences in the long-term return on investment in expensive storage facilities.     

Modelling carbon storage in highly fragmented and human-dominated landscapes: Linking land-cover patterns and ecosystem models

To extend coupled human–environment systems research and include the ecological effects of land-use and land-cover change and policy scenarios, we present an analysis of the effects of forest patch size and shape and landscape pattern on carbon storage estimated by BIOME-BGC. We evaluate the effects of including within-patch and landscape-scale heterogeneity in air temperature on carbon estimates using two modelling experiments. In the first, we combine fieldwork, spatial analysis, and BIOME-BGC at a 15-m resolution to estimate carbon storage in the highly fragmented and human-dominated landscape of Southeastern Michigan, USA. In the second, we perform the same analysis on 12 hypothetical landscapes that differ only in their degree of fragmentation. For each experiment we conduct four air-temperature treatments, three guided by field-based data and one empirically informed by local National Weather Service station data. The three field data sets were measured (1) exterior to a forest patch, (2) from the patch edge inward to 60 m on east-, south-, and west-facing aspects, separately, and (3) interior to that forest patch. Our field-data analysis revealed a decrease in maximum air temperature from the forest patch edge to a depth of 80 m. Within-patch air-temperature values were significantly different (α = 0.01) among transects (c.v. = 13.28) and for all measurement locations (c.v. = 30.58). Results from the first experiment showed that the interior treatment underestimated carbon storage by ～8000 Mg C and the exterior treatment overestimated carbon storage by 30,000 Mg C within Dundee Township, Southeastern Michigan, when compared to a treatment that included within-patch heterogeneity. In the second experiment we found a logarithmic increase in carbon storage with increasing fragmentation (r² = 0.91). While a number of other processes (e.g. altered disturbance frequency or severity) remain to be included in future experiments, this combined field and modelling study clearly demonstrated that the inclusion of within-patch and landscape heterogeneity, and landscape fragmentation, each have a strong effect on forest carbon cycling and storage as simulated by a widely used ecosystem process model.     

Simulation study of the Lower Cretaceous geothermal reservoir for aquifer thermal energy storage

Environmental Geochemistry and Health - The aquifer thermal energy storage (ATES) has gained attention in several countries as an installation for increasing the energy efficiency of geothermal...     

Temporal and spatial variation in protein,carbohydrate, and lipid levels in <Emphasis Type="Italic">Corallium rubrum</Emphasis> (Anthozoa,Octocorallia)

Red coral (Corallium rubrum) is an important component of the Mediterranean coralligenous habitat. The present study analyzes the relationship between energy storage molecule concentration (i.e. tissue balance of protein–carbohydrate–lipid levels) and the gonadal output in two populations located at different depths (16–18 m and 40–45 m depth) through a seasonal cycle (2002–2003). In June 2003, another six populations have been sampled to compare medium-scale geographical variation. The colonies sampled were less than 6 cm high, thus representing the majority of the population in the studied area. There was no clear relationship between energy storage (i.e. carbohydrate and lipid levels) and gonadal output, nor in the seasonal cycle or the spatial variation. A clear-cut seasonal trend of energy storage was detected only in the shallower population. The water temperature was warmer at 20 m depth and the water transparency (Secchi disk) was also higher (lower seston concentration) in 2003 when the same periods in 2002 and 2003 were compared (May–August). Carbohydrates seemed to be more sensitive to food constraints than lipids. The partial mortality detected in summer 2003 in the sampling area appeared to be recorded in the carbohydrate and lipid levels of this species, especially in the shallow population. The biochemical levels prove to be a useful tool to detect unusual environmental conditions that may cause partial or total mortality in benthic suspension feeders.     

1987-2008年南四湖湿地植被碳储量时空变化特征

利用研究区1987、1997和2008年的LandsatTM／ETM＋卫星遥感数据,结合实地采样调查和收集的资料,计算3个时期山东省南四湖湿地各植被类型的面积和碳储量;同时依照不同覆被类型（植被类型）的平均碳储量将各覆被类型的斑块划分为不同储碳等级,绘制3个时期的南四湖湿地植被碳格局图,分析植被碳储量的时空变化特征、变化产生的原因和变化对湿地的潜在影响。研究结果表明：研究前期（1987年）植被储碳格局存在着明显的植被碳储量以湖南北中心线向两岸增大的带状特征,研究中后期（1997-2008年）带状储碳格局不断破碎化并最终消失。整个研究期高储碳等级的斑块面积不断减小,低储碳等级的斑块面积增加。湿地植被碳储量呈现前期基本稳定后期显著减少的特征,1987、1997和2008年湿地植被碳储量均值分别为1．07、1．08和O．64TgC,1987-1997年湿地植被碳储量平均年增加0．001TgC,变化幅度不大;1997-2008年年减少0．04TgC,下降较明显。其中自然植被碳储量在整个研究期内持续减少,人工植被碳储量呈现先增加后减少的波动变化特征,分析认为这一变化特征产生的主要原因是南四湖地区多因子驱动的土地覆被变化活动。通过区域湿地植被的碳平衡动态分析认为,植被碳储量（碳库）的减少可能会导致整个湿地碳储量的入不敷出,使整个湿地碳汇能力下降甚至可能变为碳源。     

Differential use of stored sperm during oviposition in the damselfly Calopteryx splendens xanthostoma (Charpentier)

Female Calopteryx splendens xanthostoma (Charpentier) (Odonata), have two discrete sperm storage organs, the bursa copulatrix and the paired spermathecae. We used the Random Amplified Polymorphic DNA(RAPD) profiling technique to determine from which sperm storage organ spermatozoa were used to fertilise eggs during behaviourally distinct oviposition bouts. During oviposition bouts following remating sperm from the bursa copulatrix are largely used to fertilise eggs, but when females avoid remating before an oviposition bout the sperm used to fertilise eggs are derived mainly from the paired spermathecae. Our observations suggest that female C. s. xanthostoma can avoid male paternity assurance mechanisms by a combination of behavioural and anatomical adaptation: the reason(s) they do so is unclear. Received: 28 November 1995/Accepted after revision: 5 August 1996     

Ultrastructural localization of metal binding sites in the kidney of the Antarctic scallop Adamussium colbecki

The functional morphology of kidney cells and the intracellular localization of metal storage sites were studied by electron microscopy and X-ray microanalysis in the Antarctic scallop Adamussium colbecki (Smith) collected at Gerlache Inlet, Terra Nova Bay, Antarctic in December 1990. Kidney cells of A. colbecki show the same basic cytoarchitecture of other Pectinidae, but the nephrolithes localized in the main vacuoles show a low degree of mineralization. The sites of heavy metal storage are: (1) the main vacuole of the renal cell, where Fe, Zn and Cu are associated with concretions, (2) the basal membranes and (3) the lysosomes of amoebocytes, in which Ag, Se, Fe and Cu occur in electron-dense particles. Finally a hypothesis for the formation and role of the Ag–Se rich particles is discussed.     

Docosahexaenoic acid accumulation in thraustochytrids: search for the rationale

Thraustochytrid protists characteristically accumulate high amounts of lipids, much of which is comprised of the polyunsaturated fatty acid, docosahexaenoic acid (DHA). Since DHA is important in human health, thraustochytrids have attracted much attention from the point of view of biotechnology. However, the biological rationale of DHA production in the storage lipids of these organisms is not clear. We carried out three experiments to study this. (1) The fate of lipids in thraustochytrids during development was studied by staining lipids of vegetative cells with the fluorescent vital stain for lipids, namely Nile blue, following the growth of the cells. The fluorescent lipid bodies decreased in abundance in freshly formed motile limaciform amoeboid cells and subsequently disappeared when they moved away. When vegetative cells produced vast extensions of plasma membrane, the ectoplasmic net elements (EN), the fluorescent lipids appeared to be transported to them. (2) Changes in lipids and DHA during starvation were examined in cells with enhanced lipid and DHA contents and those in which they were not enhanced. Cells in which lipids and DHA were enhanced by refrigerating them for 48 h survived starvation for a longer period. Compared to cells that had not been refrigerated, total fatty acids, as well as DHA were marginally higher in pre-refrigerated cells, while palmitic acid levels were lower. Starvation of cells resulted in a gradual decrease of absolute concentrations and percentage levels of DHA after 8 days, while percentage of palmitic acid levels increased. (3) The relationship between DHA and specific gravity of cells was studied by comparing cells pre-refrigerated as above with those which were not pre-refrigerated. Refrigerated cells with increased lipids and DHA showed higher specific gravities than non-refrigerated cells. We suggest the following roles for storage lipids and DHA in thraustochytrids: (1) lipids serve as energy sources during movement of cells and for production of EN; (2) DHA in storage lipids become distributed in the plasma membrane when EN are formed; (3) DHA is preferably utilized as a fatty acid energy reserve during starvation and (4) an unknown mechanism results in negative buoyancy of cells when total lipids and DHA are marginally enhanced. DHA in storage lipids might be crucial to the survival of thraustochytrid cells.