基因型和胚龄对小麦未成熟胚离体培养反应的影响

本文对34种基因型的小麦未成熟胚在离体培养中的反应进行了比较。结果表明,94％的供试基因型愈伤组织诱导率都可达到80％以上,若排除供体植株环境条件的不同和接种过程中的人为因素可能造成的影响,不同基因型的愈伤组织诱导率看来没有根本的差异。愈伤组织分化率因基因型的不同变动在0—60％之间,平均为32.7％。虽然同一基因型的盾片愈伤组织分化率在不同年份中有所不同,但是愈伤组织是否具有再生能力?看来是个稳定的遗传性状。因此小麦未成熟胚对愈伤组织诱导的反应和愈伤组织的再生能力可能具有不同的遗传基础。本文的结果还表明,虽然最适于培养的未成熟胚的大小为1毫米左右,伹小至0.3毫米的未成熱胚仍能以几乎100％的频率形成愈伤组织,60％左右的愈伤组织能分化出再生檀株,只是所需的时间比1毫米左右的胚较长。     

HBsAg重组DNA转化中国地鼠卵巢细胞二氢叶酸还原酶阴性突变株的细胞染色体变化及致瘤性

整合了含乙型肝炎病毒表面抗原(HBsAg)基因和dhfr基因的CHO-dhfr~-细胞,其染色体的畸变率和畸变类型都比亲代CHO-dhfr~-细胞高。但转化前后两系细胞的重要特性都未发生变异,即两者的染色体总数无差别,都是20条。两系细胞株接种裸鼠,均未发现有致瘤性。     

糙叶败酱挥发油镇静作用的研究

本文观察了败酱科植物糙叶败酱(Patrinia scabra Bunge)根和根茎中制得的挥发油的镇静作用,井与黄花败酱挥发油做了比较。结果表明,此油灌胃给予数组小鼠,剂量0.45ml/kg,显示如下的作用:[1]能显著延长由于腹腔注射戊巴比妥钠(50mg/kg)引起的小鼠睡眠时间,但其作用强度弱于黄花败酱挥发油。(2)一次灌胃给予小鼠大剂量10.46g/kg的糙叶败酱挥发油,连续观察10天,动物外观正常,无一死亡,体重增加与对照组相似。     

大肠杆菌棉子糖操纵子α—半乳糖苷酶表达的调节控制

The alpha-galactosidase, coded for by the first structural gene rafA in the plasmid determined raf operon was an inducible enzyme. In contrast to lac or mel operon, raf operon has more strict structural specificity for inducers. The enzyme can be induced by melibiose and raffinose, or weakly by D-galactose, but not by structurally related sugars such as lactose, PNPG etc.. The alpha-galactosidase forming capacity as function of growth curve reached a single peak at the end of the logarithmic phase of the growth. The structure and regulation of raf operon is similar to those of lac operon. The repressormor-mediated negative control plays a major role in the regulation of raf operon, and cAMP-CAP mediated positive control is also involved in the regulation. When 0.4% glucose was added into the medium with other carbon sources, the expression of the enzyme was repressed by 2-3 fold. Transient catabolite repression has been observed neither in inducible nor constitutive alpha-galactosidase expression. Based on alpha-galactosidase assay, in mutant strains CA8306(cya) and CA8445 (cya, crp) the expression level of raf operon was only 9% and 2.5% of that in wild type strain respectively. The glucose effect or the repression in cya mutant can be abolished by 1-5 mmol cAMP. The constitutive alpha-galactosidase expression in cya and cry double mutant (CA8445) remains repressible by glucose, but irreversible by cAMP, suggesting cAMP-CAP complex is not the exclusive mediator of the catablite repression.(ABSTRACT TRUNCATED AT 250 WORDS)     

鲢、鳙在天然条件下的摄食强度(Ⅱ)武汉东湖鲢、鳙周年摄食强度的研究

武汉东湖的鲢(Hypophthalmichthy molitrix)鳙(Aristichthys nobilis)在天然条件下摄食强度具季节性变化。摄食强度高峰处于夏季,低谷处于冬季。在实验条件下,按周年采样期间水温变化范围,测定鱼的肠管排空率。食物通过鱼肠管时间(Y_p—h)与水温(X_t—℃)的关系为: 鲢Y_p=270.63 X_t~(0.6408) 鳙Y_p=280.46 X_t~(0.6642) 根据修正后Bajkov公式(D=C (24.A)/n),估算鱼的日粮。鱼日粮(Y_D)与水温(X_t)关系为: 鲢Y_D=0.2683e~(0.1503X_t) 鳙Y_D=0.0075X_t~(2.2715) 计算鱼在天然条件下周年月粮及年粮。鲢、鳙对天然饵料年消耗量分别为18.924公斤及17.39公斤,饵料系数分别为18.02及13.38。     

High frequency differences between high and low voltage electrocorticograms in the ovine fetus

Dawes (1986) has stated that, "The difference between high and low voltage activity depends solely on the presence in the latter of higher amplitude oscillations with relatively low frequency superimposed on the low voltage components as shown by spectral analysis". We have tested the constancy of the high frequency section of the power spectrum of the electrocorticogram in 7 near-term sheep fetuses. Under sterile conditions we implanted biparietal electrodes in the dura and a ground lead subcutaneously on the scalp. Five days after the surgery, with the animal standing quietly in the laboratory, we acquired the fetal electrocorticograms. Data were acquired during several high and low voltage electrocorticographic cycles in each animal. Two hundred power spectra were obtained during high and low voltage fetal electrocortical activity and statistically analyzed by paired t-test to discern differences in power between the high and low voltage pattern at each frequency (n = 7). We found that at all frequencies between 4 and 12 cycles/s the high voltage electrocorticogram had significantly more power than the low voltage electrocorticogram (P less than 0.05). This is in accordance with the established literature. We also observed that from 17 through 24 cycles/s the low voltage electrocorticogram is significantly higher than the high voltage electrocorticogram (P less than 0.05). In this frequency range the power of the high voltage expressed as a percentage of the power of the low voltage were respectively, 80, 74, 71, 66, 64, 64, 67, 64. These differences are of considerable magnitude and may be physiologically important.     

“引黄济青”输水沿线水生生物分布与蓄水库富营养化关系的研究

“引黄济青”是国家“七五”重点工程,由黄河下游博兴县境内打渔张闸引水,在渠首沉沙后,再经惠民、东营、潍坊和青岛的10个县区约253km的明渠输送,到达唠山县棘洪滩蓄水库蓄存,实现向青岛市日供水3.0×10~5m~3。明渠输水过程中,来白沿线的营养物质会污染水体,加之输水在库中滞留时间长,会不会发生富营养化,这是社会普遍关注的问题。     

稀土元素对甜菜种子萌发,幼苗生长及块根产量的影响

本文研究了稀土元素对甜菜的生物效应。结果表明,稀土元素可显著地提高种子萌发率,促进幼苗生长,增加幼苗根系活力、叶片净光合速率与块根产量,并明显地降低了甜菜叶片细胞膜在低温下的透性,即提高了叶片的抗寒力。     

Effect of density on age-specific mortality in Drosophila: a density supplementation experiment

Age-specific mortality rates were studied at two adult density levels in four inbred lines of Drosophila melanogaster. In experimental populations, adult densities were maintained at constant levels throughout the experiment by replacing dead flies with live, marked mutants. In control populations, densities declined naturally as the cohorts aged. For all experimental populations the best mortality model is the two-stage Gompertz model, with slower mortality acceleration at older ages. Flies in the experimental populations generally lived longer than flies in control populations, regardless of sex, genotype, or initial density level. The data demonstrate that deceleration of age-specific mortality rates at older ages is not caused by declining cohort densities. Mortality deceleration is a real phenomenon that raises serious questions about the evolution of senescence.     

以异源四倍体体细胞杂种为父本杂交培育三倍体柑桔植株的研究

以 3个柑桔原生质体融合而来的四倍体体细胞杂种为父本 ,与二倍体单胚性种柚子 (Citrusgrandis)以及单多胚混合型品种“华农本地早”桔 (C.reticulata)有性杂交 ,授粉后 90 d,发现种子干瘪 ,大部分种子的胚败育。将干瘪种子在 MT附加 1mg/L GA3 或 50 0 mg/L麦芽浸出物的培养基中 ,经培养抢救 ,有 2 5.6%的种子萌发成苗或继续进行胚的生长 ,后者进一步诱导能形成丛芽 ,经试管嫁接或诱导生根形成完整植株。共获得 6个组合 73棵完整植株 ,染色体数检查表明 ,2 0株为三倍体 (2 n=3x=2 7) ,32株为二倍体 (2 n=2 x=18) ,8株为非整倍体 ,其它 13株还有待于进一步检查。