镍胁迫对玉米苗根系生长及膜保护系统的影响

[目的]研究镍(Ni<'2+>)胁迫对玉米(Zea mays L.)根系生长及膜保护系统的影响.[方法]以玉米为材料,研究了不同浓度Ni<'2+> 胁迫对玉米幼苗根系生长、根系活力及根系中超氧化物歧化酶(SOD)、过氧化物酶(POD)活性和丙二醛(MDA)含量的影响.[结果]不同浓度Ni<'2+> 处理对玉米幼苗根系具有低浓度的促进效应和高浓度的抑制效应,且随着浓度的增加抑制效应逐渐增强.根系长度、鲜重、根系活力、SOD活性、POD 活性、MDA 含量在3个处理阶段(10、30、30 d)变化趋于相同;随着玉米幼苗的生长,各项指标变化更加明显.根系活力在Ni<'2+>浓度为50 mg/kg(土)时最强,随着Ni<'2+>浓度的升高而逐渐减弱;根系保护酶系统中SOD和POD活性随着Ni<'2+>浓度的增加而呈现先升高后下降的变化趋势,在Ni<'2+>浓度为50 mg/kg(土)时出现峰值;根系细胞内MDA 含量在低Ni<'2+>浓度处理下增幅较小,Ni<'2+>浓度在100～800 mg/kg(土)时增加显著.[结论]Ni<'2+> 浓度低于50 mg/kg(土)时对玉米幼苗期根系的生长有促进作用,而超过该浓度则表现为抑制作用,Ni<'2+>浓度越高,抑制作用越明显.     

不同水分条件对蚬木幼苗生长的影响

[目的]阐明水分条件对蚬木幼苗生长的影响.[方法]通过盆栽控水试验,研究9种水分处理下蚬木苗高、地径生长量和叶绿素 含量的变化.[结果]不同控水条件下,蚬木苗高和地径增长量及叶绿素含量均存在显著差异;适宜的水分条件有利于提高幼苗的生长和叶绿素含量,而水分胁迫,如不供水或连续7 d浇水会降低蚬木幼苗生长量和叶绿素含量.[结论]蚬木苗期对水分比较敏感,应加强苗期的水分管理.     

芘胁迫对玉米幼苗生长及生理指标的影响

[目的]探讨芘胁迫对玉米幼苗生长及生理指标的影响.[方法]通过水培试验,研究了4个浓度(0、0.5、1.0和2.0 mg/L)的芘对2种玉米市祥1号(敏感品种)和广甜3号(耐性品种)幼苗生长及生理指标的影响.[结果]在试验浓度范围内,随芘浓度的升高,市祥1号叶绿素a和叶绿素b含量呈先升高后降低的趋势,相对生长量和绝对生长速率呈下降趋势,根系和叶片丙二醛(MDA)含量呈上升趋势;广甜3号相对生长量、绝对生长速率和叶绿素a含量呈先上升后下降趋势,叶绿素b和根系MDA含量呈上升趋势,叶片MDA含量呈下降趋势.与对照相比,市祥1号在0.5～1.0 mg/L芘处理对叶绿素a和叶绿素b含量显著增加,芘浓度≥2.0 mg/L时则显著降低,芘浓度≥1.0 mg/L时根系和叶片MDA含量显著增加,而相对生长量和绝对生长速率显著降低;广甜3号在芘浓度≥1.0 mg/L时叶绿素a和叶绿素b含量显著增加.芘浓度与敏感品种市祥1号的相对生长量和绝对生长速率呈显著负相关,与根系MDA含量呈显著正相关;芘浓度与耐性品种广甜3号叶绿素b含量和根系MDA含量呈显著正相关.[结论]为玉米苗期的管理措施提供了依据.     

壳寡糖对玉米种子萌发及幼苗生长的影响

[目的]研究壳寡糖对玉米(Zea mays L.)种子萌发及幼苗生长的影响.[方法]利用不同浓度壳寡糖处理玉米种子及幼苗,研究壳寡糖对玉米种子萌发及幼苗生长的影响.[结果]壳寡糖能够有效地提高玉米种子胚乳淀粉酶活力,提高胚根、胚芽的生长速率,促进玉米种子萌发;同时,壳寡糖还可提高玉米幼苗叶片叶绿素含量以及根系活力,促进幼苗生长.其中,浓度为0.1 μg/ml壳寡糖的促进作用最为明显.[结论]壳寡糖具有促进玉米种子萌发及幼苗生长的作用.该研究可为壳寡糖的应用提供理论支持.     

外源水杨酸对番茄耐盐性的影响

[目的]探讨外源水杨酸(SA)对番茄耐盐性的影响,为SA在番茄生产中的应用提供理论依据.[方法]在盐胁迫条件下,对番茄喷施不同浓度(1、2、5 mmol/L)的SA,测定其叶片叶绿素含量、可溶性糖含量、过氧化物酶(POD)活性、相对电导率及根系活力,研究外源SA处理对番茄幼苗耐盐性的影响.[结果]外源SA能不同程度地提高番茄叶片叶绿素含量、可溶性糖含量、POD活性和根系活力,而降低叶片相对电导率.其中浓度2 mmol/L SA对叶绿素含量、POD活性和相对电导率的影响最佳,而浓度5 mmol/L SA对可溶性糖和根系活力的影响较大.[结论]外源SA能够提高番茄幼苗的耐盐性,但适宜施用浓度和施用周期尚需进一步研究.     

水分胁迫对二、四倍体薄皮甜瓜苗期生理生化特性的影响

[目的]揭示甜瓜倍性与抗旱性的关系,为多倍体甜瓜抗旱育种提供理论依据.[方法]测定并比较二倍体和同源四倍体薄皮甜瓜在水分胁迫下苗期的生长指标、叶片水分状况、叶绿素舍量、可溶性糖含量、脯氨酸含量.[结果]在水分胁迫下,二倍体和同源四倍体薄皮甜瓜苗期株高、茎粗、干物质重量、叶绿素含量都有不同程度减少,而叶片中可溶性糖和脯氨酸含量均呈上升趋势,说明水分胁迫抑制了二、四倍体薄皮甜瓜植株的生长.四倍体的薄皮甜瓜株高胁迫指数、茎径胁迫指数、干物质胁迫指数、叶绿素含量、相对可溶性糖含量和脯氨酸含量显著高于二倍体,二倍体叶片中自由水含量和水分饱和亏明显高于四倍体,说明四倍体薄皮甜瓜在苗期抗旱性比二倍体强.[结论]多倍体育种可以作为甜瓜抗性育种的一种有效途径.     

烯效唑对小麦幼苗生长的影响

[目的]研究不同浓度烯效唑浸种对小麦幼苗生长的影响.[方法]分别用0、20、40、60 mg/L烯效唑浸种处理,研究其对小麦幼苗形态指标和生理指标的影响.[结果]与对照相比,20、40、60 mg/L烯效唑处理后,幼苗株高分别降低9.35、10.78、12.16 cm,根干重分别增加7.18%、4.39%、1.73%.根冠比分别增加30.3%、20.5%、16.4%.总叶绿素含量分别增加8.9%、27.1%、37.8%,丙二醛含量分别降低28.7%、16.1%、6.9%,呼吸强度分别降低61.1%、19.6%、16.9%;烯效唑浓度为20 和40 mg/L时,根系活力分别增加53.8%、19.4%,而60 mg/L时根系活力比对照组降低11.3%.[结论]小麦生产过程中,烯效唑使用浓度以20 mg/L为宜.     

不同pH对甘草种子萌发及幼苗生长的影响

[目的]研究甘草种子萌发和幼苗生长的最适pH,优化甘草中药材产业化栽培技术.[方法]用不同pH溶液(pH 3,5,6,7,8,9,10,11)处理甘草种子7 d,分别计算其发芽率、发芽势、发芽指数,并测定胚根胚芽长度及整株幼苗鲜重;采用水培法,以不同pH的营养液(pH为5,6,7,8,9)培养甘草幼苗,30 d后测定其生物量、药用成分,蛋白质,氨基酸,可溶性总糖,淀粉,丙二醛含量以及硝酸还原酶和过氧化物酶活性等指标.[结果]pH为6时甘草种子的发芽率最高、出苗整齐,且发芽后胚芽长度及幼苗鲜重均有最大值;溶液培养pH为6时,甘草生物量、甘草酸、蛋白质、淀粉等含量最高,同时其硝酸还原酶和过氧化物酶活性也最大.[结论]pH6时最利于甘草种子的萌发,幼苗生长及药用成分的积累.     

调节剂浸种对马铃薯不同芽位母薯生理代谢及根系形态的调控效应

[目的]通过比较不同芽位马铃薯母薯生理代谢及根系形态的变化,分析了植物生长调节剂对马铃著生长的调控效应.[方法]采用盆栽试验,浸种使用不同植物生长调节剂,研究母薯生理代谢及根系理化性状变化,探讨植物生长调节剂对马铃薯生育进程的影响.[结果]DTA-6可以提高顶部芽位母薯播后21 d内还原糖含量,对播后42～56 d根系长度、根系体积及根系干重均有提高的调控效应;DTA-6可以提高基部芽位母薯播后7～28 d内可溶性糖含量,但减少播后42～49 d根系干物质积累.SODM对顶部芽位母薯的调控效应与DTA-6基本相同,但是它对可溶性糖含量提高的效果好于DTA-6.就基部芽位母薯而言,SODM可以提高播后7～28 d内可溶性糖含量,降低播后42～49 d内根系干物质的积累,但调控效应较弱.[结论]植物生长调节剂能够通过调控马铃署母薯生理代谢及根系形态的变化进而影响马铃薯生长发育进程.     

Pb胁迫对柳树根系形态和生理特性的影响

[目的]评价柳树对重金属Pb的忍耐能力及应用于植物修复的潜力.[方法]采用溶液培养研究了不同浓度Pb胁迫对苏柳172和垂柳2种柳树的根系形态、根系活力以及叶片保护酶活性和渗透调节物质的影响.[结果]Pb处理显著抑制2种柳树的根系伸长,垂柳根系表面积、根体积、根平均直径先增后降,苏柳172根系表面积、根体积、根平均直径均受到Pb的显著抑制.2种柳树的根系活力均下降:超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性和脯氨酸(Pro)含量均先增加后下降;可溶性蛋白含量、叶绿紊含量在一定程度内均降低,只是变化的幅度和进程不同.[结论]为柳树应用于重金属修复具有重要的参考价值.     

Growth of mandibular prognathism after pubertal growth peak

Until recently, the signal transduction pathways involved in the processes of tumor growth have been poorly understood. In the present study, we investigated cell surface receptors which utilize phosphatidylinositol (Pl) turnover/Ca2+ mobilization as a signal transduction pathway to regulate cell growth in a metastatic human lung carcinoma cell line, PG. We found that purinoceptor agonists, including ATP and its analogs, and bombesin, an amphibian tetradeca-peptide of mammalian homology gastrin-releasing peptide, induced rapid transient increase of cytoplasmic-free Ca2+ in PG cells loaded with fura-2. The Ca2+ responses were derived both from release from internal stores and the opening of plasma membrane Ca2+ channels. HPLC analysis of inositol 1,4,5-triphosphate (Ins(1,4,5)P3) and its isomers showed a receptor-linked phospholipase C activation by ATP and bombesin. Although ATP and bombesin were both able to induce Pl turnover and Ca2+ mobilization in PG cells, they had differential growth regulatory effects on PG cells. Treatment with bombesin stimulated PG cell growth while treatment with ATP inhibited significantly PG cell growth. Pharmacological studies showed that the purinoceptors on PG cells were of the P2 subtype. Other hydrolysis-resistant P2 purinoceptor agonists, including ATP gamma S and AMP-PNP, were as effective as ATP in stimulating Pl turnover and Ca2+ mobilization as well as in inhibiting PG cell growth in vitro, suggesting the potential usefulness of such ATP analogs in clinical trials. Preliminary results suggest G protein involvement in the differential regulation of ATP and bombesin signal transduction pathways.     

Growth of rats' kidneys after unilateral uretero-caval anastomosis

1. The relative significance of reduced excretion of urinary constituents and reduced renal mass, as stimuli to growth of one kidney after the other has been removed, has been investigated. 2. To abolish the excretory function of one kidney without removing it, the right ureter was drained into the vena cava through a compound cannula for 6 weeks. Uretero-caval anastomoses were performed in twenty-four male rats at 10 weeks of age: six survived without evidence of ureteric obstruction (and a further five with minimal obstruction). 3. The rats with anastomoses grew less than six other rats from which the right kidney had been removed or six which had been submitted to a sham operation, and their plasma urea and creatinine concentrations were higher. 4. Relative to body weight, the dry weight of each kidney after uretero-caval anastomosis without obstruction was 18% greater than after sham operation; taking both kidneys together, the total increase was almost as much as in the left kidney alone after right nephrectomy (46%). 5. Histologically and in terms of DNA concentration, the growth of both kidneys after uretero-caval anastomosis was of the same kind as in the left kidney after right nephrectomy. 6. The return of urine from one kidney into the blood provided a powerful stimulus to renal growth in spite of the restraining effect of increased renal mass.     

Growth hormone levels in acromegaly after external radiotherapy

A 56-year-old acromegalic patient was treated with conventional radiotherapy. One year after treatment, the patient's growth hormone level was normal and remained so for a full year. Subsequently, the growth hormone level returned to the pretreatment, acromegalic range. The attainment of a normal growth hormone level after treatment of acromegaly is no assurance that the level will remain normal. Repeated growth hormone level determinations are necessary before cure can be considered permanent.     

Growth characteristics of the aortic arch after the Norwood operation

OBJECTIVES: We sought to characterize the growth of the reconstructed aortic arch after the Norwood operation (NO). BACKGROUND: The first stage of surgical palliation of hypoplastic left heart syndrome (HLHS), the NO, includes augmentation of the aortic arch with homograft. Growth characteristics of the reconstructed aortic arch, which is comprised of both native aortic tissue and homograft, have not been characterized. METHODS: Retrospectively, we examined the serial echocardiograms of 50 patients with HLHS who underwent NO to determine the diameter of the reconstructed transverse arch. Measurements were taken immediately after NO and at two other points (1 to 11 years of age). In addition, the autopsy specimens of 10 other patients with HLHS who underwent NO were examined to determine the contribution of native aortic tissue to the overall size of the reconstructed arch at the time of death (12 to 34 months). RESULTS: The diameter of the transverse aorta increased after NO in all subjects. Its rate of growth paralleled that seen in the normal population, though the reconstructed arch had a significantly larger diameter throughout childhood. Examination of autopsy specimens demonstrated a mean increase in circumference of the native aortic tissue of 0.67 cm (p value <0.01), whereas there was no significant change in homograft circumference. CONCLUSIONS: After reconstruction of the aortic arch in HLHS, the diameter of the arch continues to increase throughout childhood, and this increase is due to growth of the native aortic tissue.     

Growth hormone in postmenopausal women after long-term oral estrogen replacement therapy

Studies of estrogen effects on growth hormone (GH) and its pulsatile release in postmenopausal women have typically utilized estrogen replacement therapy (ERT) of relatively short duration (days to weeks). The purpose of this study was to compare GH measures from healthy postmenopausal women who were on oral ERT for 3 years or more (n = 24; mean ERT duration = 16.1 years) with women not on ERT (NERT; n = 40). Blood samples were drawn remotely every 20 min for 24 h and then analyzed for mean 24-h GH, mean GH during sleep, and mean 24-h insulin-like growth factor-I (IGF-I). GH peak analyses were also performed. Mean 24-h GH and GH during sleep were significantly higher and IGF-I was significantly lower in ERT women compared with NERT women. In addition, use of long-term ERT was associated with more GH peaks relative to women not on ERT, but no change in GH peak amplitude or area. GH was not related to age in either group. GH was strongly and negatively correlated with measures of adiposity in NERT women but not in ERT women. In conclusion, long-term oral ERT is associated with increased circulating GH and decreased IGF-I levels, even after many years of treatment.     

Growth and development four years after treatment for the Trichuris dysentery syndrome

A follow-up study is reported of 18 children 4 y after treatment for the Trichuris dysentery syndrome (TDS) and matched control children. The TDS children were initially severely stunted and had extremely low developmental levels. They showed catch-up in height of 1.9 z-scores even though they remained in very poor environments. Their intelligence quotients, school achievement and cognitive function remained significantly lower than those of the controls. Controlling for their earlier developmental levels, the TDS children showed a small improvement in mental development relative to the controls.     

Growth of growth hormone-treated and nontreated children before and after tethered spinal cord release

Children with myelomeningocele (MM) are very short and respond to treatment with recombinant human growth hormone (RHGH) with an acceleration in growth. Following primary closure of the MM, a tethered spinal cord may produce neurologic and orthopedic deformities. We compared the short-term growth rate and length standard deviation score (L-SDS) for stature of 13 prepubertal children with MM (7 males, 6 females, mean age 6.1 +/- 2.5 years) before and after symptomatic tethered spinal cord release (TCR) to an untreated asymptomatic matched control group. We also compared these data to 7 prepubertal children with MM and growth hormone inadequacy who had TCR and were then treated with RHGH. TCR significantly increased the growth rate compared with matched controls (p < 0.01); however, TCR and RHGH in combination provided an increased gain in growth rate and L-SDS over TCR alone (p < 0.01). Tethered spinal cord influences the growth rate of children with MM. Further study is necessary to evaluate the relationship of the tethered spinal cord to growth and treatment of growth failure.