水稻杂交后代表观直链淀粉质量分数与蜡质基因(CT)n微卫星多态性的相关性

以来自２ 个水稻杂交组合的后代遗传群体为材料,研究了蜡质基因（ Ｗｘ） 微卫星标记（ＣＴ）ｎ 多态性与稻米表观直链淀粉质量分数（ ｗ（ＡＡ）） 之间的相关性． 第１ 个群体是浙农８０１０ 与嘉育２９３ 的杂交Ｆ６ 代育种品系,双亲均为籼稻,ｗ（ＡＡ） 分别为８ ．７％ 和２５．６ ％ ,Ｗｘ 基因型为分别为（ＣＴ）１８（ＣＴ）１８ 和（ＣＴ）１１（ＣＴ）１１ ．另一群体为ＣＭ１０１ 与ＩＧＲＡ４０９ 杂交Ｆ５ 家系,亲本ＣＭ１０１ 为一个粳型糯稻,Ｗｘ 基因型为（ＣＴ）１８（ＣＴ）１８ ;ＩＧＲＡ４０９ 为籼稻,ｗ（ＡＡ） ＝ ２７．５％ ,Ｗｘ 基因型为（ＣＴ）１１（ＣＴ）１１ ．结果发现,在２ 个杂交组合的后代群体中,高ｗ（ＡＡ） 材料Ｗｘ 基因型均为（ＣＴ）１１（ＣＴ）１１ ,低ｗ（ＡＡ） 及糯稻的均为（ＣＴ）１８（ＣＴ）１８ ,中等ｗ（ＡＡ） 材料的则为（ＣＴ）１８（ＣＴ）１１ 的杂合体．统计分析表明,Ｗｘ 基因型与ｗ（ＡＡ）之间存在显著的相关性,在浙农８０１０×嘉育２９３ 和ＣＭ１０１ ×ＩＧＲＡ４０９ 两个群体中相关系数分别达０ ．９５０９ 和０．９７０４．     

Do you not like Pigou, or do you not understand him? Tax aversion and revenue recycling in the lab

Tax-aversion reduces the likelihood that price rationing can be a politically viable tool for environmental protection. We examine the case of the classic Pigouvian tax to control a negative externality, and consider how recycling the revenues, labeling of the tax and information about its purpose affects the support for taxation. We test the support for taxation within a single-price market experiment, in which purchases by some buyers impose external costs on others. Observing behavior consistent with tax-aversion, we also find that recycling the revenues to more narrowly targeted groups seems to increase support for taxation. In the absence of narrow revenue recycling, labeling a Pigouvian instrument as a ‘tax’ may significantly lower the likelihood of voter support.     

210Pb as a dietary indicator in the Antarctic pelagic community

The naturally occurring radionuclide ²¹⁰Po is useful as a tracer of diets of marine organisms. Data for ²¹⁰Pb, the grandparent of ²¹⁰Po, are less abundant: we therefore report here ²¹⁰Pb concentrations in a substantial collection of marine biota obtained from the Antarctic Ocean during the SIBEX II cruise in 1985. The general levels of ²¹⁰Pb are within the range of previously published data but, as in the case of ²¹⁰Po, there are differences which can be associated with variations in the diet of the organism. The levels of ²¹⁰Pb in the krill Euphausia superba show seasonal changes which can be interpreted in terms of changing diet. In a simple classification of the pelagic food chain, the levels of ²¹⁰Pb tend to increase from omnivores to filter-feeders to predators.     

Polonium-210 and lead-210 in marine food chains

²¹⁰Po and ²¹⁰Pb have been measured systematically in whole animals, muscle and hepatopancreas of crustaceans and of molluscan cephalopods representative of a pelagic and benthic food chain. The same nuclides were also measured in liver, pyloric caecum, stomach contents and muscle of tuna. The concentration factors from sea water to whole animals were approximately constant along both food chains, being of the order of 10⁴ for ²¹⁰Po and 10² for ²¹⁰Pb. The highest concentration factors were found in shrimp of the genus Sergestes. In muscle, the concentration factors were an order of magnitude less; in the hepatopancreas, they were an order of magnitude higher, reaching 10⁶ in shrimp of the genus Sergestes. Such concentrations imply alpha-radiation doses of the order of 10 rem per year and more in this organ, which contains about 50 to 90% of the ²¹⁰Po in the whole animal in the 11 species analyzed. A detailed study of the intracellular behaviour of ²¹⁰Po in the hepatopancreas is clearly indicated. ²¹⁰Po can be used as a sensitive natural tracer in biological systems. Thus, feeding Meganyctiphanes norvegica in the laboratory on food low in ²¹⁰Po led to an approximate value of about 61/2 days for the biological half-life of ²¹⁰Po in the hepatopancreas of this euphausiid. Furthermore, the data on ²¹⁰Po and ²¹⁰Pb in the cephalopod hepatopancreas allowed the time of conservation of frozen squid which had been bought at the market to be estimated.     

Seasonal availability and sensitivity of two field-collected mayflies for the development of a standardized toxicity test

Ecologically relevant toxicity tests may provide the best protection of sensitive aquatic fauna, but without established culturing or test methodology for such organisms, results may be unreliable and difficult to repeat. Further, field-collected organisms may not be feasible for routine testing purposes, as often required for permitted discharges. This study examined the feasibility of testing two field-collected mayflies, Isonychia bicolor and Maccaffertium spp., over a 1-year period. Seasonal comparisons of availability indicated I. bicolor and Maccaffertium spp. were most abundant during the winter months, resulting in 31 and 49 % of total organisms collected in 2009, while summer was the most difficult time to collect either species. Initial testing in January 2009 resulted in the highest no observable effect concentration (NOEC) values for survivorship (8 g NaCl for I. bicolor and 4 and 8 g NaCl/L for Maccaffertium spp.) when tested at 9°C. Subsequent tests conducted at 20–23°C resulted in 7-day NOEC values substantially lower (mean?=?1.44 and 1.59 g NaCl/L). Geometric means of exuviae indicated a dose-dependent response for I. bicolor exposed to NaCl, while no dose-dependent response was observed for Maccaffertium spp. with average number of molts varying from 4.93 in the 0.5 g NaCl/L concentration to 3.80 for control organisms followed by 2.24 (1 g NaCl/L). Averages again increased to 3.09 in the 2 g NaCl/L concentration, but declined in the highest concentrations (4–10 g NaCl/L). Based on the results of this feasibility study, field-collected mayflies appear to be too unpredictable in test responses, and therefore, such tests would be unreliable as stand-alone indicators of effluent toxicity.     

Polonium-210 content of marine shrimp: Variation with biological and environmental factors

The concentrations of ²¹⁰Po and ²¹⁰Pb were determined in more than 30 species of marine shrimp. Samples were collected in the years 1977 to 1980; most were from the Mediterrancean Sea near Monaco, the remainder from Kuwait, South Africa, USA and Great Britain. The median ²¹⁰Po concentration was 8.0 pCi g^-1 dry wt in the whole shrimp and 85 pCi g^-1 dry in the hepatopancreas; the corresponding ²¹⁰Po:²¹⁰Pb activity ratios were 77 and 138, respectively. The range of concentrations covered more than two orders of magnitude for both nuclides. The variations in the levels of ²¹⁰Po, in particular, could be related to biological and environmental factors; thus, penaeid shrimp had ²¹⁰Po at median concentrations some three to four times higher than carid shrimp, and there was a steady increase in the median ²¹⁰Po concentration as one moved from estuarine to coastal to pelagic to deep-pelagic species. ²¹⁰Po levels were highest in 3 species of deep-pelagic penaeids, where a median ²¹⁰Po concentration in the whole shrimp of 43 pCi g^-1 dry wt was found. The natural radiation dose received by the hepatopancreas of such individuals will be of the order of 100 rem per yr. Elevated ²¹⁰Po was also found in 4 species collected near Kuwait. The ²¹⁰Po data are interpreted as indicating changes in the food regime of different shrimp; specifically it is suggested that ²¹⁰Po-rich items such as hepatopancreas, faecal pellets and organic particulates are likely to be important in the diet of shrimp which feed at depth in the ocean. It is suggested further that the ultimate availability of ²¹⁰Po to the foodchain depends on its form in sea water, and the need for information concerning the degree of organic binding of ²¹⁰Po in natural waters in stressed.     

POLLUTANT REMOVAL FROM COAL-ASH BASIN EFFLUENT1

ABSTRACT: The drainage system for an ash basin serving a coal-fired power plant at the Savannah River Project, Aiken, South Carolina, has been studied for 15 months to determine abiotic and biotic characteristics and mechanisms of pollutant removal. Measurements made included temperature, dissolved oxygen, pH, turbidity, alkalinity, conductance, flow rate, sulfate, nitrate, and phosphate. In addition, neutron activation analysis was employed to determine concentrations of 40 chemical elements in water, benthos, bacterial, plant, invertebrate, and vertebrate samples collected at six sampling stations. Five-day toxicity tests were performed using organisms from within and from outside the system. Conductance, pH, alkalinity and sulfate concentration varied little throughout the system. Temperature, dissolved oxygen, turbidity, nitrate, phosphate, and flow rate decreased at stations farther removed from the ash basin. Concentrations of most chemical elements measured were greatest in benthos (75 percent of total) and least in water (less than one percent of total), indicating that a major removal mechanism was sedimentation of suspended particulate matter. Eight elements (Br, Ca, C1, Cd, Na, Sb, Se, and Zn) were more highly concentrated in one or more biotic forms than in benthos. Among heavy metals only Cr was concentrated to a greater extent by plants than by animals. Midges were the greatest concentrators of Fe, Cu, Cr, Hg, Co, Sb, and As among all organisms. Plants concentrated only 15 percent of the total heavy metal concentration found in the benthos. Light, metals were more highly concentrated in animals than in plants, although all plants were found to possess 19 percent of the concentration present in the benthos and water. As and Sb were in low concentration within the system; however, on a percentage basis, these potentially toxic elements were relatively highly concentrated by a number of organisms. Active metals (Ca, Na, and K) and halogens (CI, Br, and I) were highly concentrated by most organisms. Active metals were more concentrated in crayfish and mosquito fish, Gambusia affinis, than in benthos, whereas most organisms had higher concentrations of halogens than were found in benthic sediments. Primary producers within the system were least efficient in concentration of all elements except Mn. Consumers (invertebrates and vertebrates) were found to possess highest concentrations of all other elements. Organisms found within the drainage system were observed to be able to survive a five-day toxicity test at any point within the system, whereas organisms not existing within the system were observed to vary in their resistance to the drainage system environment. The findings of this study demonstrate the necessity for the operation of entire food chains in pollutant removal and indicate potential means for increasing cycling efficiency by selective addition of resistant consumers to such a system.     

RESPONSES OF HETEROTHROPHIC BACTERIAL POPULATIONS TO pH CHANGES IN COAL ASH EFFLUENT1

ABSTRACT: Total culturable heterotrophic bacteria in a coal ash basin and drainage system were monitored over a period of two years. In the first year heavy (bottom) ash was sluiced to the basin resulting in a pH of 6.5. During the second year fly ash was precipitated and added to the sluice lowering the basin pH to 4.6. Sulfate concentrations during 1975 ranged from 16–73 ppm (mean 33) and in 1976 from 44–88 ppm (mean 72). Mean annual basin temperatures were 28.8 and 26.0 C, respectively. Approximately 1500 m in the receiving swamp below the basin, mean pH and temperature were 6.8 and 22.2 C for the first year, and 5.4 and 22.1 C for the second. Total culturable bacteria and diversity (colony types) were reduced at all sampling stations by 44 and 30 percent, respectively, whereas the percentage of the population comprised of chromagenic bacteria increased by 51 percent at the lower pH; Data indicated the pH had a greater effect than did water temperature when temperature was within the range of 15–25 C. The predominant genera within the system in the first year were Bacillus, Sarcina, Achromobacter, Flavobacterium, and Pseudomonas. In the second year, at the lower pH, predominant genera were Pseudomonas, Flavobacterium, Chromobacterium, Bacillus, and Brevibacterium.