研究型生物化学实验设计与实践

以"鲫鱼脑乙酰胆碱酯酶(AChE)的活性测定及影响因素"为内容设计了一个研究型生物化学教学实验.要求学生课前查阅文献了解乙酰胆碱酯酶活性测定的应用,拟定实验方案,课上通过实验讨论底物浓度、缓冲液pH值、反应温度对酶活力的影响,课后以科研论文的形式写出实验报告.教学效果调查显示,学生对相关知识点的理解和掌握程度、学习主动性、分析问题解决问题的能力及创新能力都有了显著提高.     

浅谈黄粉虫

黄粉虫,也叫大黄粉虫、黄粉甲,又名面包虫或麸子虫,属昆虫纲拟步行甲科粉甲属.黄粉虫一年为一个世代,其生活史包括卵、幼虫、蛹、成虫四个时期,属于完全变态昆虫.<生物学>(七年级上册)第38页提到黄粉虫的探究实验,笔者通过观察、实验等对黄粉虫有了以下了解:     

黄粉虫马氏管显微结构观察及功能分析

对黄粉虫老龄幼虫的马氏管进行了解剖、显微镜及电镜观察,结果表明：黄粉虫幼虫马氏管多为6根,着生在前后肠的交界处,并常超过体长.马氏管不同部位有不同的结构,决定了其具有不同的功能,其与肠壁细胞分泌的多浆物质组成隐肾管复合体,便于从粪便中回收水分,维持体内水分、盐分的平衡.黄粉虫幼虫马氏管结构观察和功能分析对研究其代谢生命活动的正常进行及进一步开发利用、进化研究等都具有重要意义.     

稀土元素对黄粉虫生长繁殖的影响

用含不同剂量稀土的饲料喂养黄粉虫，发现在每公斤饲料中添加100mg氧化镧可使黄粉虫的一些重要的生理指标发生明显的变化：①在生长力方面，幼虫的生长速度显著加快，幼虫的存活率有所提高；②在繁殖力方面，雌虫提前两天产卵，雌虫的产卵期缩短了5天，雌虫的产卵量显著提高，实验结果还表明稀土在黄粉虫体内的蓄积量很低，稀土处理50天的幼虫主要营养成分含量无显著变化．     

黑里河自然保护区昆虫资源（二）

3.3蜻蜓目(Odonata) 3．3．1生物学特性古蜻蜓类远在石炭纪化石中已有发现,是起源较早的昆虫．成虫与稚虫都为肉食性,幼虫喜食浮游及蚊类幼虫,成虫捕食蚊类、小形蛾类、叶蝉等．是一类重要益虫．有时亦同类相残．大形者,亦能取食小鱼和蝌蚪．头大,活动自如,后部是空的,松松地连在胸部,就像一个圆球与旋轴,使头部能上下、左右转动．触角刚毛状．复眼甚大,占头部的大部分,视觉相当敏锐,能看见空中小虫,冲上去攻击．两对翅膜质,透明,脉序网状,翅前缘近翅顶处常有翅痣．蜻蜓的交配也在飞行中进行．雌虫将卵产在水中,所谓“蜻蜓点水”就是产卵时的表演．     

驴粪作为黄粉虫饲料的研究

畜禽粪便无害化处理和资源化利用已成为社会普遍关注和急需解决的焦点问题.为探寻大型养驴场驴粪资源化利用和绿色处理途径,本研究进行了黄粉虫采食和分解驴粪的研究.将驴粪和黄粉虫常规饲料(玉米面、豆浆渣、干馒头)按梯度比例混合后,比较不同驴粪含量组(0%-100%)黄粉虫幼虫的死虫率、虫长、蛹重以及驴粪消耗量等参数,评价黄粉虫幼虫对驴粪作为饲料的适应性.实验结果表明,驴粪可以作为黄粉虫饲养的一种饲料.驴粪添加量对各组黄粉虫平均体长影响不大.适当的驴粪量有助于增加蛹的平均重量,驴粪添加量为20%时蛹重最大.驴粪含量40%时,有利于黄粉虫幼虫对驴粪的分解处理,也可以节约常规饲料.食物中驴粪含量越高对饲养的黄粉虫幼虫死亡率影响越大.     

有机磷毒物中毒的机制

有机磷毒物(有机磷农药和化学神经性毒剂)中毒的机制,主要是有机磷毒物与乙酰胆碱酯酶(AChE)结合成中毒酶,AChE失去催化水解乙酰胆碱(ACh)的活性;导致胆碱能神经突触间隙ACh大量蓄积。大量ACh对受体的作用大大增强和延长,导致中枢和周围胆碱能神经系统功能紊乱;此外,毒物也可直     

胆碱酯酶与有机磷农药中毒

有机磷农药中毒的机制,主要是有机磷农药与乙酰胆碱酯酶(AChE)结合成中毒酶,AChE失去催化水解乙酰胆碱(Ach)的活性;导致胆碱能神经突触间隙ACh大量蓄积.大量ACh对受体的作用大大增强和延长,导致中枢和周围胆碱能神经系统功能紊乱;此外,农药也可直接作用于胆碱能受体.中毒酶形成后有3种去向.     

浅谈潮虫——鼠妇和卷甲虫

鼠妇和卷甲虫都是节肢动物门、甲壳纲、软甲亚纲、等足目，潮虫亚目的动物，是一类小型陆生的甲壳纲动物，成虫体长一般在2～15mm之间，最大者可达30mm。体长卵圆形，背腹扁平。身体分头部、胸部和腹部三部分。头部有触角2对，第1触角很小，第2触角发达；胸部发达，有胸肢8对.     

科苑集粹

天蚕蛾属大型蛾类,品种很多,有的成虫展翅可达25～30厘米,颇为漂亮。它的幼虫,长相奇特,体色艳丽。尤为令人惊奇的是头部有一双奇大无比的眼睛,还有那一只巨大的牛鼻子,样子十分可笑。     

Expression of Drosophila melanogaster acetylcholinesterase (DmAChE) gene splice variants in Pichia pastoris and evaluation of its sensitivity to organophosphorus pesticides

Acetylcholinesterase(AChE) is a key enzyme used to detect organophosphorus pesticide residues by the enzyme inhibition method.An accidental discovery of a mutant strain with AChE activity was made in our laboratory during the process of AChE expression by Pichia pastoris.The pPIC9 K-Drosophila melanogaster acetylcholinesterase(DmAChE)-like expression vector was constructed by codon optimization of this mutant strain,which was transformed into P.pastoris GS115,and positive clones were selected on yeast peptone dextrose(YPD) plate with G418 at 4.0 mg/mL.The GS115-pPIC9 K-DmAChE-like strain was subjected to 0.5% methanol induction expression for 120 h,with a protein band at 4.3 kDa found by the tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) pattern of the fermentation supernatant.After preliminary purification by ammonium sulfate precipitation,the enzyme activity was detected to be 76.9 U/(mL·min).In addition,the pesticide sensitivity test proved that DmAChE-like is selective and sensitive to organophosphorus pesticides.     

Hyphens for disambiguating phrases: effectiveness for young and older adults

The purpose of this study was to investigate whether hyphens that disambiguate phrasing in ambiguous sentences influence reading rate and reading comprehension for younger and older adults. Moreover, as working memory (WM) has been implicated in age-related changes in sentence comprehension for both auditory and written materials, we asked if it contributed to comprehension of our sentences with hyphenated and non-hyphenated ambiguous noun phrases (NPs), predicting that the hyphens would reduce WM load. Twenty younger (M?=?24?years) and 20 older (M?=?73?years) adults read sentences with either ambiguous or non-ambiguous NPs that were either hyphenated or not. Both reading times for the sentences and accuracy on Yes/No questions were measured. Results indicated that younger adults read sentences more rapidly than the older participants whether sentences were presented word-by-word or as complete sentences. Both younger and older adults read sentences with ambiguous hyphenated NPs faster than sentences with ambiguous non-hyphenated NPs. Yes/No question accuracy distinguished reading of the sentences with ambiguous hyphenated phrases from those with ambiguous non-hyphenated phrases for older, but not for younger adults. Regression analyses showed that age contributed to both accuracy and reading times on this task, whereas WM did not.     

Children are not like older adults: a diffusion model analysis of developmental changes in speeded responses

Children (n = 130; M(age) = 8.51-15.68 years) and college-aged adults (n = 72; M(age) = 20.50 years) completed numerosity discrimination and lexical decision tasks. Children produced longer response times (RTs) than adults. R. Ratcliff's (1978) diffusion model, which divides processing into components (e.g., quality of evidence, decision criteria settings, nondecision time), was fit to the accuracy and RT distribution data. Differences in all components were responsible for slowing in children in these tasks. Children extract lower quality evidence than college-aged adults, unlike older adults who extract a similar quality of evidence as college-aged adults. Thus, processing components responsible for changes in RTs at the beginning of the life span are somewhat different from those responsible for changes occurring with healthy aging.     

A Global Developmental Trend in Cognitive Processing Speed

Children respond more slowly than young adults on a variety of information-processing tasks. The global trend hypothesis posits that processing speed changes as a function of age, and that all component processes change at the same rate. A unique prediction of this hypothesis is that the overall response latencies of children of a particular age should be predictable from the latencies of young adults performing the same tasks--without regard to the specific componential makeup of the task. The current effort tested this prediction by examining the performance of 4 age groups (10-, 12-, 15-, and 19-year-olds) on 4 different tasks (choice reaction time, letter matching, mental rotation, and abstract matching). An analysis that simultaneously examined performance on all 4 tasks provided strong support for the global trend hypothesis. By plotting each child group's performance on all 4 tasks as a function of the young adult group's performance in the corresponding task conditions, precise linear functions were revealed: 10-year-olds were approximately 1.8 times slower than young adults on all tasks, and 12-year-olds were approximately 1.5 times slower, whereas 15-year-olds appeared to process information as fast as young adults.     

Functional reading difficulties in Denmark

In this first Danish study of adult reading skills, 1124 adults between 18 and 67 years of age participated in an interview about reading habits and skills, and 445 were tested individually at home using six common texts. Great care was taken to ascertain that subjects were representative of the whole adult population and that the texts covered most types of everyday reading. Three percent of the participants were found to have severe functional reading difficulties and a further 9 percent to have moderate difficulties. Regression analyses found several unique predictors of reading difficulties: age (adults over 45 years reading more poorly than younger adults), limited basic education, no vocational training nor higher education, and a small amount of reading needed at work. The rate of poor readers was about four times higher among persons with low income than among others. Men and women read equally well although men tended to rate themselves lower as readers than women did. Methodological issues and some educational implications are discussed.     

Community involvement of persons with severe retardation living in community residences

A national survey was conducted with 294 community residential facilities (CRFs) serving adults with severe retardation. Respondents were asked to rate 38 community-based activities twice: one rating representing the activity involvement of the residents living in the CRFs, and one rating representing the perceived activity involvement of "average," well-integrated community members. Nonhandicapped community members were perceived to have significantly more involvement in 30 activities than adults living in CRFs. Group home and foster home residents were perceived to be more involved in employment or day activities outside the residence, use of health care services, walking or wheelchair strolling for pleasure, and use of parks or zoos than nonhandicapped community members.     

Speech and Language Difficulties in Children With and Without a Family History of Dyslexia

According to recent psychological theories of situation model construction, readers routinely and quickly construct inferences that elaborate causal antecedents of explicit events in the text, but not inferences about causal consequences. The process of forecasting lengthy causal chains into the future is taxing on working memory, so these inferences are either not constructed or their construction consumes a comparatively large amount of reading time. This study collected self-paced sentence reading times from younger and older adults who read expository texts on scientific and technological mechanisms. Readers were also measured on working memory span, general world knowledge, reasoning ability, and reading frequency. Multiple regression analyses on the reading times revealed that (a) causal consequence inferences were more time consuming than causal antecedent inferences and (b) noncausal elaborative inferences were not constructed. The pattern of beta weights for inference variables was remarkably similar for younger and older adults and was unaffected by other measures of individual differences. The process of constructing causal inferences is therefore stable and predictable across different groups of readers.     

An Event‐Related Potential Study of Adolescents' and Young Adults' Judgments of Moral and Social Conventional Violations

The neurocognitive development of moral and conventional judgments was examined. Event‐related potentials were recorded while 24 adolescents (13 years) and 30 young adults (20 years) read scenarios with 1 of 3 endings: moral violations, conventional violations, or neutral acts. Participants judged whether the act was acceptable or unacceptable when a rule was assumed or removed. Across age, reaction times were faster for moral than conventional violations when a rule was assumed. Adolescents had larger N2 amplitudes than adults for moral and neutral, but not conventional, acts. N2 amplitudes were larger when a rule was removed than assumed for moral, but not conventional, violations. These findings suggest that the neurocognitive mechanisms underlying moral and conventional judgments continue to develop beyond early adolescence.     

Outcomes and satisfaction of two optional cadaveric dissection courses: A 3‐year prospective study

Teaching time dedicated to anatomy education has been reduced at many medical schools around the world, including Nova Medical School in Lisbon, Portugal. In order to minimize the effects of this reduction, the authors introduced two optional, semester‐long cadaveric dissection courses for the first two years of the medical school curriculum. These courses were named Regional Anatomy I (RAI) and Regional Anatomy II (RAII). In RAI, students focus on dissecting the thorax, abdomen, pelvis, and perineum. In RAII, the focus shifts to the head, neck, back, and upper and lower limbs. This study prospectively analyzes students' academic achievement and perceptions within the context of these two, newly‐introduced, cadaveric dissection courses. Students' satisfaction was assessed anonymously through a questionnaire that included items regarding students' perception of the usefulness of the courses for undergraduate teaching, as well as with regards to future professional activity. For each of the three academic years studied, the final score (1 to 20) in General Anatomy (GA), RAI, and RAII was on average 14.26 ± 1.89; 16.94 ± 1.02; 17.49 ± 1.01, respectively. The mean results were lower in GA than RAI or RAII (P < 0.001). Furthermore, students who undertook these courses ranked them highly with regards to consolidating their knowledge of anatomy, preparing for other undergraduate courses, and training for future clinical practice. These survey data, combined with data on participating students' academic achievement, lend strong support to the adoption of similar courses as complementary and compulsory disciplines in a modern medical curriculum. Anat Sci Educ 10: 127–136. © 2016 American Association of Anatomists.