Data for: INFLUENCE OF MATERNAL AGE ON THE EFFECTS OF SELENO-L-METHIONINE IN THE MODEL ORGANISM DAPHNIA PULEX UNDER STANDARD AND HEAT STRESS CONDITIONS

We evaluated the influence of maternal age on the effects of seleno-methionine (SeMet) for lifespan, reproduction, and heat-stress resistance in D. pulex. Populations of animals were maintained under previously established laboratory culture protocol conditions. All D. pulex cultures were maintained in COMBO media at a density of 20 animals per 1 L media. COMBO media and Animate stock solutions were prepared as described by Kilham, Kreeger, Lynn, Goulden, & Herrera, 1998. For dose-finding study a total of five SeMet treatment concentrations were analyzed: 0-g SeMet/L, 1-g SeMet/L, 2-g SeMet/L, 4-g SeMet/L, and 8-g SeMet/L. The highest treatment (8-g SeMet/L) is the concentration of SeMet at which 50% of the population were dead (LD 50) in adult Daphnia magna after a 48-hour exposure48. A 50% dilution was applied to obtain the remaining treatments. In the control group (0-g SeMet/L) no additional Se was added. Each SeMet treatment was assessed using a population of n=20 individuals, that were followed as populations throughout their lifespan. Mortality and presence of offspring were recorded throughout the lifespan of each population. Daphnia pulex maternal populations were established from the third brood of our laboratory maintenance D. pulex culture (maternal age ~ 12 days). Neonates ( 24 hours of age; n=80) were obtained from the maintenance population and randomized into four maternal populations. These maternal populations each consisted of n=20 individuals that were housed in 1 L beakers containing 1,000 ml COMBO media and allowed to age under standard laboratory maintenance conditions. All experimental animals exposed to SeMet were obtained from these maternal populations when the mothers were 8-days of age (early life (2nd-3rd) brood) and when the mothers were 32-days of age (late life (12th-14th) brood).
For the lifespan analysis, offspring from maternal populations were combined into a single pool from which offspring were randomized into three SeMet treatment groups [(1 maternal population x 3 SeMet treatments) x 25 replicates per SeMet treatment]. This was conducted once when the maternal populations produced an early life brood and repeated when the maternal populations produced a late life brood. For the heat induced stress analysis, offspring were tracked by maternal population. Within the maternal population tracks, offspring were randomized into the three SeMet treatments and housed as populations, creating one experimental group for each maternal population. This was repeated for replicate groups to ensure that each SeMet treatment is assessed in 8 populations for each maternal age group; giving a total of n=24 exposure groups per maternal age [(4 maternal populations x 3 SeMet treatments) x 2 replicates].
Daphnia were submitted to the Virginia-Maryland College of Veterinary Medicine Toxicology Lab for quantification of Se content by atomic absorption spectrometry.

本研究旨在评估母体年龄对硒蛋氨酸（SeMet）对蜉蝣属（D. pulex）寿命、繁殖和耐热应激影响的影响。动物种群在先前确立的实验室培养方案条件下进行维持。所有蜉蝣属的培养均在COMBO培养基中进行，密度为每升培养基20只动物。COMBO培养基和Animate储备溶液的制备方法参照Kilham、Kreeger、Lynn、Goulden及Herrera于1998年的描述。在剂量寻找研究中，分析了五种SeMet处理浓度：0-g SeMet/L、1-g SeMet/L、2-g SeMet/L、4-g SeMet/L和8-g SeMet/L。最高处理浓度（8-g SeMet/L）为SeMet在48小时暴露后导致蜉蝣属成虫死亡50%的浓度（LD 50）。将此浓度稀释50%以获得其余处理浓度。在对照组（0-g SeMet/L）中未添加额外的硒。每个SeMet处理均使用n=20个体的种群进行评估，并追踪其整个生命周期。记录了每个种群在整个生命周期内的死亡率及其后代的存在。蜉蝣属母体种群由实验室维持的D. pulex培养的第三代（母体年龄约为12天）建立。从维持种群中获取的新生儿（年龄≤24小时；n=80）被随机分配到四个母体种群中。每个母体种群由n=20个体组成，被安置在含有1,000毫升COMBO培养基的1升烧杯中，并在标准实验室维持条件下进行老化。所有接触SeMet的实验动物均来自这些母体种群，当母体年龄为8天（早期（第2-3代）产卵）和32天（晚期（第12-14代）产卵）时获取。对于寿命分析，母体种群的后代被合并为一个单一群体，从中随机分配到三个SeMet处理组[(1个母体种群 x 3个SeMet处理) x 每个SeMet处理25个重复]。当母体种群产生早期产卵时进行一次，当母体种群产生晚期产卵时重复进行。对于热应激诱导的分析，通过母体种群追踪后代。在母体种群追踪中，后代被随机分配到三个SeMet处理组，并以种群的形式进行饲养，为每个母体种群创建一个实验组。重复进行重复组以确保每个SeMet处理在每个母体年龄组中均被评估8次；总共为每个母体年龄组提供n=24个暴露组[(4个母体种群 x 3个SeMet处理) x 2个重复]。蜉蝣属样本被提交至弗吉尼亚-马里兰大学兽医学院毒理学实验室，通过原子吸收光谱法进行硒含量的量化。