不同耐旱基因型玉米根系生理性状研究

为了研究玉米根系生理性状与耐旱性的关系,以生长于田间的玉米掖单13(耐旱)和丹玉13(不耐旱)为试验材料,分别于苗期、拔节期、孕穗期和灌浆期测定其根系分布、保水力、吸收面积、氧化力、硝酸还原酶活性以及总糖和还原糖含量等项指标.结果表明:耐旱基因型玉米在21 cm以下土层中的根干重以及根系氧化力极显著高于不耐旱基因型玉米根系(P＜0.01);根系保水力、可溶性糖含量、还原糖含量以及硝酸还原酶活性显著高于不耐旱基因型玉米根系(P＜0.05);根系总吸收面积和活跃吸收面积在两基因型玉米根系之间差异不显著(P＞0.05).这些结果表明,根系所具有的吸水、保水能力和生物节水能力对玉米耐旱能力的发挥起着重要作用.     

Increased incidence of tumor metastases in female mice

Most of the tumor cells injected into the tail vein of mice fail to survive at the site of arrest in the lungs, but the percentage of surviving cells is higher in females than in males. The surviving cells, however, grow at a similar and constant rate in both sexes.     

玉米不同耐旱性品种根系构型和动态建成研究

以不同耐旱性玉米为试验材料,利用根箱冲洗根系的方法进行取材,研究并比较不同耐旱性玉米根系在黑土中的构型分布和动态建成。结果表明:在整个生育期内,耐旱品种较不耐旱品种根系干重大,根系相对发达;耐旱品种玉米根系在水平方向和垂直方向上的分布广,平均单株占有空间大,深层土壤中的根干重以及深层土壤中的根重占总根重的比率大,深层根系优势明显。     

A mutation of the circadian system in golden hamsters

A mutation has been found that dramatically shortens the period of the circadian locomotor rhythm of golden hamsters. The pattern of inheritance of this mutation suggests that it occurred at a single, autosomal locus (tau). Wild-type animals have rhythms with free-running periods averaging about 24 hours; animals heterozygous for the mutation have periods of about 22 hours, whereas homozygous animals have rhythms with periods close to 20 hours. Animals that carry the mutant alleles exhibit abnormal entrainment to 24-hour light:dark cycles or are unable to entrain.     

Increased incidence of lymphoma after injections of mice with cells differing at weak histocompatibility loci

Newborns of two congenic strains of mice, in which the incidence of leukemia is low, differing only at the weak H-1 locus, were. injected at birth with adult spleen cells of the parent and of the congenic strain. A marked increase in the incidence of lymphoma ensued in those mice of both strains injected with cells from the other strain. The experiment lends some support to the idea that transplantation immunologic mechanisms may play a role in the genesis of lymphomas.     

耐热性不同的番茄品种荧光特性和抗氧化体系对高温胁迫的响应

以番茄耐热品种＂中杂9号＂和感热品种＂串珠樱桃＂为试材,研究了在25～50℃高温胁迫条件下耐热性不同的两个品种在叶绿素荧光、抗氧化体系和膜透性方面的差异。结果表明,耐热性强的品种具有较高的PSⅡ最大光化学效率（Fv/Fm）、实际PSⅡ光化学转化效率（φPSⅡ）、光化学猝灭系数（qP）、较高的依赖叶黄素循环耗散过剩激发能的能力（NPQ）、有活性的反应中心数量多（RC/CS）,捕获的光量多（ABS/CS）。另一方面,耐热性强的品种抗氧化酶,包括超氧化物歧化酶（SOD）活性、过氧化氢酶（CAT）活性和过氧化物酶（POD）活性以及抗氧化剂抗坏血酸（AsA）含量均高于不耐热品种。     

耐抽薹萝卜品种比较试验

对7个本地常用的耐抽薹萝卜在产量、耐抽薹性、商品性等方面进行比较,认为白雪春2号、特新白玉春、韩白雪3个品种表现出产量高、根形好、根皮全白、耐抽薹性好等优点,适合在本地推广栽培。     

Polyamines and antioxidant defense system are associated with cold tolerance in centipedegrass

Physiological responses to low temperature were analyzed in a chilling-tolerant centipedegrass (Eremochloa ophiuroides) accession, Shao Guan (SG), in comparison to the commercial cultivar, Common. Lower levels of ion leakage and higher chlorophyll (Chl) concentration were observed in SG than in Common during chilling stress. The maximum photochemical efficiency, the actual photosystem II (PSII) efficiency, photochemical quenching efficiency, and net photosynthetic rate were decreased during chilling stress in both genotypes, with higher levels of these parameters shown by SG than Common. In addition, higher activities of superoxide dismutase (SOD), catalase (CAT), ascorbate-peroxidase (APX) and glutathione reductase (GR), and higher concentrations of ascorbic acid (AsA) and glutathione (GSH) were observed in SG than in Common. Moreover, higher concentrations of putrescine (Put), spermidine (Spd), and spermine (Spm) were observed in SG than in Common. Correlation analysis indicated that SOD, CAT, APX and GR activities, and AsA and GSH concentrations showed high correlation to Put, while APX, GR, and AsA concentrations were correlated to Spd. Exogenous Put or Spd increased antioxidant enzyme activities and chilling tolerance. The results suggested that polyamine-regulated antioxidants are important for chilling tolerance in centipedegrass and protect plants against chilling induced oxidative damage.     

Role of melanopsin in circadian responses to light

Melanopsin has been proposed as an important photoreceptive molecule for the mammalian circadian system. Its importance in this role was tested in melanopsin knockout mice. These mice entrained to a light/dark cycle, phase-shifted after a light pulse, and increased circadian period when light intensity increased. Induction of the immediate-early gene c-fos was observed after a nighttime light pulse in both wild-type and knockout mice. However, the magnitude of these behavioral responses in knockout mice was 40% lower than in wild-type mice. Although melanopsin is not essential for the circadian clock to receive photic input, it contributes significantly to the magnitude of photic responses.     

Homograft tolerance in mice: use of urethan and sublethal irradiation

Adult mice [CBA/J (H-2(k))], which received either a single sublethal dose of x-radiation (500 rad) or urethan plus 500 rad, were given intravenous injections of C3H/HeJ (H-2(k)) spleen or bone marrow cells (18 to 42 x 10(6) cells per mouse) or both, for 3 days. C3H/HeJ tail-skin homografts were retained (over 130 days) by these mice, whereas BALB/cJ (H-2(d)) homografts all were rejected within 33 days. Similarly irradiated or urethan-treated controls (or controls treated with a combination of both), which did not receive C3H cells, rejected both homografts. Specific homograft tolerance is induced in adult mice by this procedure.     

赛程安排的数学模型与计算机求解

要求安排n支球队(n≥5)参赛的单循环赛,并使各队做到尽量公平的赛程安排,用手工编排很难做到公平、合理,并且效率不高。利用数学建模轮转和配对的方法,给出了合理、公平的最佳赛程安排,并用QBASIC高级语言在计算机上实现了算法。     

核黄素对盐胁迫下杜梨叶片抗氧化系统的影响

为探讨外源核黄素对盐胁迫下杜梨叶片抗氧化系统的影响,以梨砧木杜梨幼苗为供试材料,在水培条件下,研究了外源施加不同浓度核黄素对200 mmol/L Na Cl胁迫下其叶片抗氧化酶活性、活性氧产生、膜质过氧化和抗氧化物质含量的影响。结果显示:Na Cl胁迫3 d后,杜梨叶片中超氧化物歧化酶(SOD)活性减弱,过氧化物酶(POD)、过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)、谷胱甘肽过氧化物酶(GSH-Px)、抗坏血酸过氧化物酶(APX)的活性增强,抗氧化物质谷胱甘肽(GSH)和抗坏血酸(As A)合成下降,活性氧(O2·-、H2O2)和丙二醛(MDA)大量积累。施加外源核黄素能增强Na Cl胁迫下杜梨叶片中SOD、POD、CAT、GR、GSH-Px和APX的活性,提高GSH和As A的含量,减少O2·-和H2O2的产生,降低脂质过氧化程度,有效缓解盐胁迫对杜梨叶片的过氧化伤害,其中以10μmol/L浓度的核黄素处理效果最为显著。     

光照对小鼠下丘脑视上核及乳腺组织钟基因Clock表达的影响

分析光照对泌乳期小鼠下丘脑视上核(SCN)及乳腺组织内生物钟基因Clock表达的影响.采用荧光定量RT-PCR法测定不同光照条件下SCN和乳腺组织中Clock基因的昼夜表达规律.试验发现Clock基因的mRNA不但在SCN,而且在乳腺组织也具有昼夜节律性表达.在光照-黑暗交替光制下,SCN和乳腺组织Clock基因的mRNA表达的峰值相位存在约6 h的相位差;在全黑暗条件下,Clock基因的mRNA表达存在昼夜节律,SCN和乳腺组织Clock基因的mRNA表达的峰值相位基本同步.结果显示,Clock基因的昼夜节律表达具内源性特征;光照影响Clock基因mRNA的表达.     

Rapid loss of tolerance induced in weanling NZB and B-W F1 mice

Young adult mice (30 to 43 days old) of autoimmune NZB and BIW F(1) strains failed to develop immunologic tolerance when treated with ultracentrifuged bovine gamma globulin and then challenged 12 days later. By contrast, weanling NZB and B/ W F(1) mice (18 to 25 days) as well as weanling C3H mice (16 to 19 days) became tolerant and had no serum antibody 12 days after challenge. The C3H mice remained unresponsive, but NZB and B! W F(1) mice produced antibody between days 27 and 41. The rapid loss of previously established tolerance to foreign antigens could have its parallel in the loss of tolerance to autoantigens with subsequent development of lupus nephritis and Coombs' positive hemolytic anemia in these animals.     

不同密度对耐密型玉米新品种产量的影响

对3个高产耐密型玉米品种进行了密植定额试验研究,结果表明,在中等肥力下,先行3号、郑单958、浚单20的666．7m^2适宜种植密度分别是4000、4500、4500株,此种植密度下单产分别为643．5、696．3、617．3kg。     

大白菜耐热性的生理研究 Ⅲ.酶性和非酶性活性氧清除能力与耐热性

耐热性不同的２个大白菜品种经３８℃高温胁迫后Ｏ－２含量明显增加，但耐热的亚蔬１号增幅远小于不耐热的“１０６”品种．高温胁迫使亚蔬１号的超氧物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）和抗坏血酸过氧化物酶（ＡＳＰ）活性提高，“１０６”品种除ＣＡＴ活性稍有提高外，ＳＯＤ和ＡＳＰ活性均下降．２个品种还原型谷胱甘肽（ＧＳＨ）含量增加不明显，但亚蔬１号仍稍高于“１０６”品种；抗坏血酸（ＡｓＡ）含量均减少，亚蔬１号降幅小于“１０６”品种．结果显示，在高温胁迫下，亚蔬１号较“１０６”品种具有较高的酶性和非酶性活性氧清除能力     

转基因大豆对雄性鼠生殖系统的安全性评估

以含转基因豆粕饲料喂食小鼠,观察对雄性小鼠生殖系统的影响。喂食小鼠120d后,通过PCR方法检测外源基因在睾丸中的存在情况;对睾丸组织制作石蜡切片,观察睾丸组织的病理损伤情况;通过流式细胞术检测睾丸组织中各生殖周期细胞比例;通过彗星电泳检测小鼠精子DNA损伤情况。结果表明:在睾丸组织中未检测到外源基因;睾丸组织切片未发现明显的病理学变化;试验组与对照组小鼠睾丸组织中各生殖周期精细胞比例无显著差异;未检测到精子DNA损伤。说明喂食转基因饲料对小鼠的生殖系统无显著影响。     

菜心耐热性评价及酶促抗氧化系统对高温胁迫的响应

为鉴定不同菜心品种的耐热性,以热害指数为评价指标对19份材料进行耐热性评价,并在此基础上研究了酶促抗氧化系统对人工模拟高温胁迫及恢复的响应。结果表明:通过热害指数分析,筛选出耐热品种5个、中等耐热品种11个、不耐热品种3个。对耐热品种CX10、中等耐热品种CX17和不耐热品种CX13进行人工模拟高温处理发现,37℃高温胁迫时菜心叶片的电导率、MDA含量显著升高,SOD、POD和CAT的活性,以及Mn-SOD、POD和CAT基因表达量显著增加。从增加幅度来看,耐热材料中的电导率、MDA含量增幅明显低于不耐热材料,SOD、POD和CAT的活性,以及Mn-SOD、POD和CAT基因表达量则以耐热材料中增幅最大。在胁迫恢复3 d时,与胁迫时相比,所有指标均呈下降趋势,但仍高于对照。以上结果说明,高温胁迫影响了菜心酶促抗氧化系统的正常代谢,即使高温解除后也不能恢复至正常状态,但耐热材料可通过调节自身的酶促系统减轻胁迫带来的伤害。     

Mutant Strains of Rhizobium japonicum with Increased Ability to Fix Nitrogen for Soybean

A strain of Rhizobium japonicum used in commercial inoculants was mutagenized and screened by a rapid effectiveness assay with soybean plants. Two mutant strains nodulated the roots earlier than the wild type and also expressed greater symbiotic nitrogen-fixing activity than the wild type in the presence and absence of fixed nitrogen. In addition, one of the mutants formed more root nodules than the wild type. Plants inoculated with these strains had increased dry weights ( approximately 60 percent) and nitrogen content ( approximately 100 percent) when grown in growth chambers.