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61.
Preliminary gut analysis of a recent Great Lakes invader, the round goby, Neogobius melanostomus (7.0–8.4 cm), collected from
the Detroit River, showed that they ate zebra mussels (58%), snails (6%), and other invertebrates (36%), including aquatic
insects (Hexagenia), softshelled crayfish, and zooplankton. Because zebra mussels, Dreissena polymorpha, predominated as prey,
we investigated the ability of round gobies to consume different size classes of zebra mussels. In laboratory experiments,
we examined feeding preferences of three size classes of round gobies (5.5–6.9 cm; 7.0–8.4 cm; 8.5–10.3 cm standard length)
on four different size classes of zebra mussels (6.0–9.9 mm, 10.0–12.9 mm, 13.0–15.9 mm, 16.0–18.9 mm). All sizes of round
gobies ate zebra mussels < 10.0 mm. Only the largest size class of round gobies ate larger zebra mussels (10.0–12.9 mm) when
all prey sizes were presented. The association between the total mass of zebra mussels available and the amount consumed by
round gobies increased positively up to about 6.5 g of available mussels and then levelled off. Round gobies consumed an average
of 1.0 g of mussels in 24 h. There was a significant positive relationship between gape size and standard length of round
gobies. Although larger round gobies (over the size range of fish in our study) are able to consume larger zebra mussels,
small mussels were preferred. Our findings suggest that the preference of small zebra mussels by round gobies has the potential
to alter the size structure of zebra mussel populations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
62.
The coldwater crayfish Orconectes eupunctus is endemic to the Spring and Eleven Point Rivers of Arkansas and Missouri, and appears to have been displaced from a portion
of its range by the recently introduced ringed crayfish Orconectes neglectus. We examined competition among juveniles as a potential mechanism for this crayfish species displacement through laboratory
and field experiments. Orconectes eupunctus juveniles survived and grew in stream cages in their former range, implicating biotic interactions rather than habitat degradation
in the displacement. Laboratory experiments revealed O. neglectus juveniles were dominant in the presence of limited food, whereas size rather than species determined occupancy of limited
shelter. In a field competition experiment using stream cages, O. neglectus juveniles did not inhibit growth or reduce survival of O. eupunctus juveniles. Consequently, laboratory evidence of O. neglectus dominance did not correspond with competition under field conditions. Combined with previous studies examining the effects
of O. neglectus on O. eupunctus, these results suggest that competition may not be a factor in this crayfish species displacement. Alternate mechanisms for
the apparent displacement of O. eupunctus by O. neglectus, such as differential predation or reproductive interference, should be investigated. 相似文献
63.
棉花根际亲和性高效促生细菌的分离筛选 总被引:3,自引:0,他引:3
为了从棉花根际土壤筛选能与棉花凝集素具有亲和作用的高效促生细菌,以选择性培养基从棉花根部初步筛选具有固氮能力、解磷能力及解钾能力的促生细菌,再以异硫氰酸磺(FITC)标记的棉花凝集素为复筛工具,从棉花根际促生细菌中筛选能与棉花凝集素结合的亲和性菌株,分别挑选2株固氮菌、2株解磷细菌和2株解钾细菌作为微生物肥料接种到棉花根部进行盆栽试验.观察其在根部定殖情况.结果是在选择性平板上有20%~30%的菌株具有凝集素染色阳性.盆栽试验显示,接种的6株亲和性菌株能在棉花根部成功定殖,根际细菌数量约是灭活对照的`0倍.通过初步鉴定,固氮菌株N1111为固氮菌属(Azotobacter),N2121属于德克斯氏菌属(Derxia);解磷菌株P2126属于黄单胞菌属(Xanthomonas),P1108菌株为假单胞菌属(Pseudomonas);解钾菌株K2204和K2116属于芽孢杆菌属(Bacillus). 相似文献
64.
分析了《基础生物化学》(第二版)实验教材中实验“酵母核糖核酸组分鉴定”中存在的问题,提出了改进建议。 相似文献
65.
66.
PINGPING WU JINJIAN LIU YANGCHUN XU QIRONG SHEN JIANWEN ZOU SHIWEI GUO 《Global Change Biology》2011,17(6):2196-2210
The impact of agricultural management on global warming potential (GWP) and greenhouse gas intensity (GHGI) is not well documented. A long‐term fertilizer experiment in Chinese double rice‐cropping systems initiated in 1990 was used in this study to gain an insight into a complete greenhouse gas accounting of GWP and GHGI. The six fertilizer treatments included inorganic fertilizer [nitrogen and phosphorus fertilizer (NP), nitrogen and potassium fertilizer (NK), and balanced inorganic fertilizer (NPK)], combined inorganic/organic fertilizers at full and reduced rate (FOM and ROM), and no fertilizer application as a control. Methane (CH4) and nitrous oxide (N2O) fluxes were measured using static chamber method from November 2006 through October 2009, and the net ecosystem carbon balance was estimated by the changes in topsoil (0–20 cm) organic carbon (SOC) density over the 10‐year period 1999–2009. Long‐term fertilizer application significantly increased grain yields, except for no difference between the NK and control plots. Annual topsoil SOC sequestration rate was estimated to be 0.96 t C ha?1 yr?1 for the control and 1.01–1.43 t C ha?1 yr?1 for the fertilizer plots. Long‐term inorganic fertilizer application tended to increase CH4 emissions during the flooded rice season and significantly increased N2O emissions from drained soils during the nonrice season. Annual mean CH4 emissions ranged from 621 kg CH4 ha?1 for the control to 1175 kg CH4 ha?1 for the FOM plots, 63–83% of which derived from the late‐rice season. Annual N2O emission averaged 1.15–4.11 kg N2O–N ha?1 in the double rice‐cropping systems. Compared with the control, inorganic fertilizer application slightly increased the net annual GWPs, while they were remarkably increased by combined inorganic/organic fertilizer application. The GHGI was lowest for the NP and NPK plots and highest for the FOM and ROM plots. The results of this study suggest that agricultural economic viability and GHGs mitigation can be simultaneously achieved by balanced fertilizer application. 相似文献
67.
全球野外实验网络是近年来兴起的生态学实验方法,产生了“协同分布式实验”(CDE)、“分布式协作实验”(DCE)的野外实验网络和英国生物学记录中心(BRC)的野外观察网络等具体方法,但均存在尺度小、周期短或数据偏差问题.野外实验网络的协议设计应秉持实验优于观察测量、数据数量优于数据质量和尺度优于操作的原则.综合上述方法,本研究提出利用公众科学(citizen science)获得大范围、多尺度和长周期的数据,采用环境因子作为协变量对公众参与者的实验数据集进行验证后,将其作为后验概率与作为主观概率的生态学家实验数据集进行比对,以完成数据有效性验证,克服公众参与者数据质量瑕疵,并提出了相应的统计学模型.讨论了生态学实验数据中应用先验概率、先验与后验概率的逻辑关系以及后验概率发现演化过程新关系的可能性.这种方法更符合统计学采样规范,并增加了大尺度时空的样本量.该方法有望为生态学研究所寻找的一般性理论提供方法支持,新方法可称之为“协同分布式实验2.0”(CDE 2.0). 相似文献
68.
69.
目的:探讨生物化学检验技术实验教学(Experimental biochemistry inspection teaching,EBIT)与开放式综合实验设计(Open comprehensive experiment design,OCED)的初步效果,为EBIT教学提供新型选择方案。方法:选择2012届我们所带教医学检验专业的2个班级111例学生作为研究对象,分别归入观察组和对照组,其中观察组56例,对照组55例。对照组EBIT中予以传统的模式,观察组则采用OCED模式。对比两组实验成绩、教学效果的满意度。结果:观察组的合格率显著高于对照组,差异有统计学意义(P<0.05)。观察组对教学效果的满意度显著高于对照组,差异有统计学意义(P<0.05)。结论:OCED方式应用于EBIT过程中,可获得较好的教学效果,值得推荐。 相似文献
70.
改革微生物实验教学 强化技能训练 总被引:6,自引:1,他引:5
为了提高学生的微生物实验技能,通过实验教学研究,对高职微生物实验教学进行了改革探讨。采用逻辑连贯性实验设计、加强基础实验教学、开设综合性实验强化实验技能训练。创新实验教学方法,运用多媒体展示、讲练融合增强实践动手能力。推行徒手练习、加强实验指导与严格规范操作,建立较完善的综合考核机制以调动学生实验的积极性和主动性,促进学生实验技能的提升与实验教学质量的提高。 相似文献