两种石蒜生长发育期鳞茎可溶性糖、蛋白质及POD活性的变化

以中国石蒜(Lycoris chinensis)与石蒜(Lycoris radiata)为材料,研究其生长发育期鳞茎可溶性糖、蛋白质含量及POD活性的变化。结果表明,在花芽分化前期,2种石蒜鳞茎可溶性糖、可溶性蛋白质含量均增加,并出现峰值,但从花芽分化后期直到花期结束,可溶性糖含量均持续下降;在花期,2种石蒜鳞茎可溶性蛋白质含量均处于高水平,花谢后明显下降;石蒜展叶期间鳞茎可溶性蛋白质含量明显增加,而中国石蒜花谢后可溶性蛋白质含量处于低水平。在花芽分化前期,2种石蒜鳞茎POD活性呈直线上升,但后期POD活性略有降低;花期后,2种石蒜鳞茎POD活性出现短暂的低谷,随后随着气温的降低而出现一致性上升。     

等渗盐分、干旱胁迫下冬小麦叶片部分渗透调节物质的动态变化

分别以PEG-6000、NaCl模拟干旱胁迫及盐胁迫,采用水培方法研究了抗旱耐盐冬小麦沧-6001在干旱胁迫、盐胁迫条件下叶片可溶性糖、脯氨酸和可溶性蛋白质含量的动态变化以及Na⁺、K⁺在地上部和根系的分布。结果表明可溶性糖和可溶性蛋白变化趋势相似,其含量随干旱胁迫或盐胁迫时间延长而增加,但在胁迫处理后期下降,并且随胁迫强度增加,二者出现下降时间提前;脯氨酸在干旱胁迫条件下快速积累达到峰值后下降但在胁迫处理后期再次增加,在盐胁迫条件下,随胁迫强度的增加和胁迫时间的延长而增加;Na⁺在干旱胁迫下随胁迫程度增加而下降,盐胁迫条件下随胁迫程度的增加而增加,K⁺在干旱胁迫或盐胁迫下均随胁迫程度的增加而下降,且在根系中下降的速度大于地上部。     

兴安鹿蹄草（Pyrola dahurica (H.Andr.) Kom.）雪盖前后丙二醛及渗透调节物质含量的变化

研究了自然生境下生长的兴安鹿蹄草（Pyrola dahurica (H.Andr.) Kom.）根状茎及叶片中渗透调节物质、膜脂过氧化产物在雪盖前后的变化。结果表明,在雪盖前期（10月1日~12月15日）兴安鹿蹄草根状茎及叶片中丙二醛（MDA）含量先增高,尔后下降,翌年春季雪盖后期（3月1日~4月15日）MDA含量明显低于雪盖前期,雪盖前期根状茎的丙二醛（MDA）含量低于叶片,雪盖后期高于叶片。可溶性糖、可溶性蛋白质含量在雪盖前期随着温度的下降而升高,11月中旬达到最大,尔后下降,脯氨酸含量先下降尔后升高。雪盖后期渗透调节物质含量高于雪盖前期,可溶性糖含量随气温的升高而下降,可溶性蛋白质与脯氨酸含量随气温升高而大幅度升高,而且成明显正相关。根状茎的可溶性糖含量在雪盖前期、雪盖后期低于叶片,可溶性蛋白质与脯氨酸含量在雪盖前期、雪盖后期高于叶片。兴安鹿蹄草主要通过渗透调节物质含量的变化来适应雪盖前期及雪盖后期低温环境而安全越冬。     

角倍蚜对盐肤木叶片物质代谢的影响

角倍形成初期,倍子内游离氨基酸总量增加,以几种正常叶片中含量较少的必需氨基酸增长最为明显,而可溶性糖的含量减少,碳氮比下降,有利于角倍蚜的生长繁殖;角倍形成后期,虽然倍子内游离氨基酸总量仍在继续增加,但几种重要的必需氨基酸含量却明显下降,并且可溶性糖含量成倍增加、碳氮比低于叶片,不利于角倍蚜的生长繁殖。角倍中单宁的含量约占干重的56％,而角倍蚜体内单宁含量仅为其寄主的0．84％,角倍蚜的排泄物和蜕中单宁含量分别是虫体的37．5和4．8倍,因此这可能是角倍蚜克服寄主体内单宁伤害的重要途径。     

兴安鹿蹄草(Pyrola dahurica (H.Andr.) Kom.)雪盖前后丙二醛及渗透调节物质含量的变化

研究了自然生境下生长的兴安鹿蹄草(Pyrola dahurica(H.Andr.)Kom.)根状茎及叶片中渗透调节物质、膜脂过氧化产物在雪盖前后的变化。结果表明,在雪盖前期(10月1日～12月15日)兴安鹿蹄草根状茎及叶片中丙二醛(MDA)含量先增高,尔后下降,翌年春季雪盖后期(3月1日～4月15日)MDA含量明显低于雪盖前期,雪盖前期根状茎的丙二醛(MDA)含量低于叶片,雪盖后期高于叶片。可溶性糖、可溶性蛋白质含量在雪盖前期随着温度的下降而升高,11月中旬达到最大,尔后下降,脯氨酸含量先下降尔后升高。雪盖后期渗透调节物质含量高于雪盖前期,可溶性糖含量随气温的升高而下降,可溶性蛋白质与脯氨酸含量随气温升高而大幅度升高,而且成明显正相关。根状茎的可溶性糖含量在雪盖前期、雪盖后期低于叶片,可溶性蛋白质与脯氨酸含量在雪盖前期、雪盖后期高于叶片。兴安鹿蹄草主要通过渗透调节物质含量的变化来适应雪盖前期及雪盖后期低温环境而安全越冬。     

皱皮木瓜果实发育后期品质变化及其成熟阶段的划分初探

以湖北长阳产皱皮木瓜为材料,测定果实发育后期果实鲜质量、果长、果径、果色、果实硬度以及果肉干物质量、可溶性糖含量、总酸含量和总黄酮含量等品质指标的动态变化,划分不同成熟阶段,为判断果实适宜采收期、实现优质生产提供理论参考。结果表明:(1)皱皮木瓜果实发育后期果实鲜质量、果长、果径、果肉干物质量和可溶性糖含量均呈现上升趋势;果色由绿色、黄绿色渐变为淡黄色到黄色;果实硬度、果肉总酸和总黄酮含量呈先上升后下降趋势。(2)各品质指标快速变化的时间区域存在差异,果实鲜质量在花后105~150d增加较快,果色在150d后逐渐变黄,果实硬度在花后135~165d快速下降,果肉总酸、总黄酮含量则在花后105~120d快速增加至峰值。(3)根据主成分分析结果和各品质指标的变化特点,可初步将皱皮木瓜果实发育后期划分为未成熟(花后105d之前)、早期成熟(花后120~150d)和成熟(花后165~180d)3个阶段。研究表明,随着果实成熟度的提高,皱皮木瓜果实鲜质量、果色、果肉干物质量、可溶性糖含量等指标不断升高,果实硬度逐渐下降,其食用加工品质不断提升,而在早期成熟阶段(花后120~150d)果实的药用品质则相对较高。     

亚洲玉米螟幼虫对氮、糖的吸收和利用

本文以不同含氮和含糖量的系列人工饲料为材料,研究了亚洲玉米螟Ostrinia fur nacalis(Guen6e)幼虫对氮和糖的吸收和利用。结果表明：幼虫对饲料中氮的吸收能力随虫龄增加而下降,对糖的吸收能力则随之而增强;5龄幼虫对糖的吸收能力随所食饲料中氮含量的增加而增强,而对氮的吸收则与饲料糖含量关系不大,5龄幼虫对氮和糖的消耗速率均随饲料含糖量增加而加快,但幼虫的氮利用率和虫体含氮量则随之下降;幼虫的氮消耗速率随饲料含氮量的增加而增加,而氮利用率则下降,5龄幼虫的氮利用率比3龄幼虫的氮利用率低,导致虫体含氮量的迅速下降。这些结果说明饲料中氮含量影响幼虫对糖的吸收,高龄幼虫对糖的需要量增加而对氮的需要则较稳定,饲料中糖比氮更重要。     

光照对柑橘果皮类胡萝卜素和色泽形成的影响

以“红柿柑”为试材,在柑橘果实膨大末期通过套袋遮光处理以抑制果皮光合作用,研究光照对果皮糖、叶绿素、类胡萝卜素及果实外观色泽的影响。结果表明,遮光后果皮叶绿素含量迅速下降引起果实转色提早,但各种类胡萝卜素含量及总量并未提高,而是显著下降;至果实成熟时由于遮光与光照处理的果皮叶绿素均消失,遮光果实类胡萝卜素含量低颜色变淡,与光照处理相比,遮光前期果皮糖含量下降不大,而后期下降明显;若在后期去袋照光,果皮糖含量上升,与此相应,类胡萝卜素,尤其是β-隐黄质的积累增加,颜色加深,表明光对果皮类胡萝卜素合成尤其是β-隐黄质的积累有促进作用,其原因是光以环境信号的方式影响果皮的类胡萝卜素形成。     

猕猴桃果实采后成熟过程中糖代谢及其调节

20℃下采后猕猴桃果实中淀粉酶活性快速上升于果实软化启动阶段,随着果实进入快速软化阶段,淀粉迅速水解,葡萄糖和果糖快速积累,SPS活性增加,酸性转化酶活性下降,蔗糖积累;至果实软化后期,SPS活性降低,蔗糖含量下降.AsA和低温可抑制淀粉酶活性、己糖积累、SPS活性上升和酸性转化酶活性下降,延缓蔗糖积累,相反,乙烯则可促进淀粉酶活性,加速淀粉降解和己糖积累进而直接或间接增加SPS活性,促使蔗糖积累.采后猕猴桃果实的SPS活性变化中有己糖激活效应和蔗糖反馈抑制效应.AsA、低温和乙烯等对糖代谢的调节主要是通过对SPS活性的影响而实现的.     

生长调节物质和可溶性糖含量对丹参中丹酚酸类物质积累的影响

采用盆栽实验研究了生长调节物质水杨酸（SA）、茉莉酸甲酯（MeJA）、赤霉素（GA3）对不同生长时期丹参植株中非结构糖含量、碳/氮比及根中丹酚酸类物质积累的影响;并进一步测定培养基中不同浓度蔗糖、葡萄糖、果糖对丹参毛状根中丹酚酸类物质积累的影响,对盆栽实验的结论进行了验证。结果显示,SA处理的丹参幼苗及花后期植株中蔗糖含量有增加趋势,而MeJA处理的丹参幼苗及花后期植株及GA3处理的丹参花后期植株中蔗糖积累均有降低趋势;且SA、MeJA和GA3处理对花后期植株地上和地下部分碳/氮比的影响不同。然而,SA和MeJA处理的丹参幼苗及花后期植株地上部分和根中还原糖含量、GA3处理的花后期植株根中还原糖含量均显著增加;同时,SA和MeJA处理的丹参幼苗根中迷迭香酸含量,以及SA、MeJA、GA3处理的花后期植株根中迷迭香酸含量和丹酚酸类总量显著增加。毛状根培养结果进一步证明,葡萄糖促进毛状根中迷迭香酸的产生,增加丹酚酸类总量,毛状根中迷迭香酸、丹酚酸B的积累及丹酚酸类总量与培养基中蔗糖浓度不相关。可见,丹参（植株）根中丹酚酸类物质的产生和积累受SA、MeJA和GA3的诱导,其与碳/氮比及植株中蔗糖含量没有相关性,推测植株中葡萄糖含量的增加促进根中丹酚酸类物质的积累。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.