拟南芥叶绿体分裂蛋白PARC6影响子叶与真叶的生长

在DNA、RNA及细胞水平上鉴定了叶绿体异常分裂纯合突变株parc6,子叶白化纯合突变株sco2,同时以真叶异常分裂及子叶白化双重突变株sl2作为参照,通过向培养基中施加不同浓度的蔗糖含量来探究叶绿体异常分裂对子叶和真叶生长的影响。结果显示,sco2突变株子叶白化,而真叶生长正常;parc6突变株子叶生长势及生活力显著低于野生型对照,相当于sco2突变株,而子叶白化与真叶异常分裂双重突变株sl2生长严重受阻。parc6突变株真叶的生长势与生活力也显著低于野生型,但相较于子叶则有所恢复。parc6突变株子叶生长受阻表型可以通过在培养基上补充碳源而得到恢复,sco2突变株子叶生长受阻表型可以通过补充碳源得到恢复,但叶绿体荧光参数相较于野生型仍有差异。蓝色温和凝胶电泳结合二向聚丙烯酰胺凝胶电泳结果表明parc6突变株的子叶及真叶光系统高级结构组装正常,说明parc6异常分裂的叶绿体无法生成足够的能量进而影响子叶及真叶的生长。进化分析表明,PARC6与SCO₂存在共同进化的趋势,说明子叶发育与叶绿体分裂存在一定的联系。结果指示,叶绿体大小与植物生长尤其是子叶的发育存在密切...     

大豆和苜蓿种子中葫芦巴碱含量的测定

用高效液相色谱法测定大豆和苜蓿种子内葫芦巴碱的含量的结果表明：以氨基键合柱为固定相,乙腈和水为流动相,可快速而比较准确的测定种子中葫芦巴碱含量。大豆和苜蓿种子中葫芦巴碱的含量高于葫芦巴植物的,可作为提取葫芦巴碱的原料。     

大豆种子储藏性磷对幼苗适应低磷胁迫的作用

选用种子大小不同、磷效率不同的两个大豆品种‘巴西10号’(B10)和‘本地2号’(L2),在不同供磷条件下进行营养液浇灌沙培,从大豆萌发至2片三出复叶完全展开期测定植株主要器官总磷、可溶性磷浓度、子叶可溶性蛋白、酸性磷酸酶比活性、植酸酶比活性的变化动态,探讨储藏性磷在大豆幼苗期适应磷胁迫中的作用。结果发现:(1)磷效率不同的两个大豆品种的种子中磷含量差异显著。(2)大豆萌发和幼苗生长过程中子叶的磷逐渐转入根、茎、叶中,并以转入叶中的磷最多,其中磷高效品种B10在发芽过程中子叶磷向各个器官转移的总磷量要高于磷低效品种L2,且持续时间长。(3)大豆萌发和幼苗生长过程中外源供磷水平显著影响子叶磷的转移,在外源供磷充足条件下各器官中总磷均高于低供磷条件,子叶中磷和外源磷存在补偿关系。(4)磷高效品种B10子叶中酸性磷酸酶活性在低磷条件下显著高于高磷条件,但磷低效品种L2在高、低磷间无显著差异。研究表明,大豆种子储藏性磷在幼苗期耐低磷能力建立方面具有重要作用。     

喜树种子萌发和幼苗发育过程中喜树碱含量的变化

在喜树种子萌发过程中 ,胚乳中喜树碱含量始终最高 ,但呈降低趋势 ;种皮中喜树碱含量较低 ,呈波动型上升 ;子叶和胚轴中喜树碱含量变化不明显。种子萌发后 ,随着幼苗的发育 ,子叶中喜树碱含量逐渐升高 ,出现最大值后迅速下降 ,胚轴、根和真叶中喜树碱含量持续降低 ,幼苗发育到一定时间后趋于稳定     

芸薹属中几个物种碳酸酐酶活性的比较

检测芸薹属中几种植物的碳酸酐酶在根、茎、叶中的分布和活性以及叶片净光合速率和锌元素含量的结果表明：碳酸酐酶在甘蓝型油菜的根、茎、叶中均有分布,叶中的碳酸酐酶活性最大,茎中的次之,根中的最小。不同芸薹属植物中碳酸酐酶活性的大小依序为：甘蓝型油菜〉白菜型油菜〉芜菁〉埃塞俄比亚芥。以甘蓝型油菜为例,碳酸酐酶活性的日变化呈双峰曲线,在整个生育期的变化趋势是先上升后下降,抽薹期间的碳酸酐酶活性最高。碳酸酐酶活性与净光合速率以及与锌元素含量之间均呈现显著的正相关。     

苦豆子中生物碱的分布及其在生长期内的含量变化

采用高效液相仪测定苦豆子植株不同部位和不同生长期间的生物碱含量。结果表明：苦豆子植株不同部位的总生物碱含量为21.346-41mg．g-1（DW）,以种子中为最高,花、根、果皮、根状茎、叶片、地上茎次之,复叶轴中最低;苦参碱含量为0．55-1．30m2．g-1（DW）,含量由高到低依次为种子〉花〉根〉果皮〉根状茎〉叶片〉地上茎〉复叶轴;氧化苦参碱和氧化槐果碱含量分别为3．76～12．29mg．g-1（DW）和3．36—13．33mg·g-1（DW）,这2种生物碱含量由高到低依次为种子〉花〉根〉果皮〉根状茎〉地上茎〉复叶轴〉叶片：根、根状茎、地上茎、叶中的苦参碱、氧化苦参碱和氧化槐果碱含量在7月份达到峰值;总生物碱含量在8月达到峰值。     

罗布麻苗期生长习性观察

多年生罗布麻在土温6℃时休眠芽开始伸长,且在陆续出土的习性。在陕西关中平原区,一般年份的3月中正旬开始露出苗芽尖,到5月份基本停止,种子播种的实生苗第1年在5对真叶的前地上部生长极缓慢,而根系深入地下,约为茎高的1倍。罗布麻子叶的色泽,形态,叶脉外形等以及苗期的叶形,叶色,茎色,匍匐性等在类型间皆有差异。红、白麻易于区别。罗布麻苗期茎节的生长速度与气温关系密切,苗期分枝的增长速度在地区类型间差异较大。     

大豆子叶衰老的细胞学观察

以萌发后不同时期的大豆子叶为材料,通过普通光镜和荧光显微镜观察,分析了不同时期子叶细胞的结构变化及子叶细胞内蛋白质和淀粉含量的组织化学变化.结果表明,随着种子萌发时期的延长,子叶细胞内的蛋白质和淀粉含量逐渐减少,在子叶衰老过程中,细胞内蛋白质首先消耗殆尽,淀粉的消耗速度较蛋白质慢;大豆子叶细胞在萌发后第18天时出现典型的植物编程性死亡的形态学特征,子叶细胞内营养物质的消耗诱发子叶细胞发生细胞凋亡.     

甜瓜叶系统发育动态研究

在露地、温室和不同整枝条件下研究了甜瓜子叶面积发育、单个真叶面积、单株叶面积和叶面积指数(LAI)动态,建立了子叶、真叶而积与叶径的相关关系。结果表明：甜瓜子叶的面积在破心期前迅速增长,幼苗期结束时基本完成面积扩展,子叶面积与子叶纵横径乘积之间具有高度线性关系;甜瓜真叶面积随叶龄增大呈对数增长模式,叶片横径可作为田间叶面积估算的可靠指标;甜瓜单株叶面积及群体LAI随生育期的进展呈S型变化,于果实膨大期达到峰值;不同甜瓜品种间叶系统发育模式差异不明显,但幼苗前期的叶面积大小与种子大小有关。整枝方式影响伸蔓期之后的叶系统扩展速度,因此也影响单株叶面积或LAI增长曲线的具体形状。露地甜瓜重孙蔓上发生的叶片属于无效消耗器官,应予严格控制。     

大豆再生体系的研究

选用东北地区主栽品种‘黑农41’的子叶节和胚尖作为外植体,建立了‘黑农41’的子叶节和胚尖再生体系,并对2种再生体系进行了比较.结果表明子叶节最适芽诱导培养基为MSB5+1.0 mg/L6-BA+0.2 mg/LIBA,最适生根培养基为MSB5+1.0mg/LIBA;胚尖最适芽诱导培养基为MSB5 +0.2 mg/L6-BA +0.2 mg/LIBA,最适生根培养基为MSB5+2.0 mg/LIBA,子叶节更适合作为遗传转化的受体材料.     

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.     

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.     

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.     

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.