肝细胞生长因子对主要器官/组织损伤的修复作用

肝细胞生长因子(HGF)是一种多功能的生长因子,它参与多种细胞的增殖、迁移和形态发生。HGF对多种成熟的器官／组织有营养修复作用,促进肝、肾、肺等损伤器官的再生,同时也是神经系统新的营养因子之一。本综合近年来有关献对HGF在主要器官或组织损伤中的修复作用作一概括性介绍。     

The role of plant growth regulators on direct and indirect plant regeneration from various organs of <Emphasis Type="Italic">Leucaena leucocephala</Emphasis>

Prolific differentiation of shoot buds of Leucaena leucocephala was induced from the different plant parts viz. cotyledon, hypocotyl and leaf. Adventitious shoot bud formation was recorded with prudent application of N⁶-2- (isopentenyl) adenosine and 15% (v/v) coconut water. Coconut water alone was unable to produce any beneficial effect with regard to the shoot bud proliferation but the response was augmented with the increase in concentration of N⁶-2- (isopentenyl) adenosine. However supra-optimal level of N⁶-2-(isopentenyl) adenosine was inhibitory. Best response was recorded from the cotyledon explant at 2 mg dm⁻³ N⁶-2-(isopentenyl) adenosine compared to the other two explants. Comparative assessment was undertaken following the same experimental protocol in liquid shake culture. The regenerated shoot buds were subcultured in plant growth regulator-free medium where leafy shoot emergence was recorded. Optimum regeneration of roots was observed in these shoots in presence of 1 mg dm⁻³ α-naphthalene acetic acid. Plantlets were finally hardened following standard procedures before transplantation to the field. In another experimental set up, the de-embryonated cotyledons regenerated shoot buds via callus formation. The regenerated shoots and plantlets obtained through callus mediated organogenesis could be used for rapid multiplication and also for the genetic improvement of individual clones of Leucaena leucocephala.     

Effect of plant growth regulators on ovary culture of coconut (<Emphasis Type="Italic">Cocos nucifera</Emphasis> L.)

Coconut is a cross pollinating palm, propagated only by seeds. Tissue culture is the only vegetative propagation method available for coconut. Consistent callogenesis was obtained by culturing unfertilised ovaries at -4 stage in CRI 72 medium containing 100 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.1% activated charcoal. Callusing was improved by application of 9 μM thidiazuron (TDZ). Embryogenic calli were subcultured onto somatic embryogenesis induction medium containing 66 μM 2,4-D. Stunted growth was observed in the somatic embryos after subculture onto CRI 72 medium containing abscisic acid (ABA). Maturation of somatic embryos could be achieved in Y₃ medium without growth regulators. Conversion of somatic embryos was induced by adding gibberellic acid (GA₃) to conversion medium containing 5 μM 6-benzyladenine (BA) while 2-isopentyl adenine (2iP) increased the frequency of plant regeneration. A total of 83 plantlets was produced from 32 cultured ovaries.     

光强对三种喀斯特植物幼苗生长和光合特性的影响

以块根紫金牛、地枫皮和秀丽海桐的2年生幼苗为材料,通过搭建遮阴棚设置3个光照强度,对其不同光强下的形态结构、生物量分配以及光合特性进行了比较研究,以探讨光强对喀斯特植物幼苗生长和光合特性的影响。结果表明:遮阴促进了3种喀斯特植物幼苗株高、总叶面积和冠面积等形态指标的增长。总体而言,3种植物幼苗的根生物量比和根冠比均随光强的增大而显著增大,叶生物量比、叶面积比和比叶面积均随光强的增大而显著降低。强光显著降低了地枫皮与块根紫金牛的净光合速率(Pn),非气孔限制是其Pn下降的主要因素;秀丽海桐的Pn随光强的升高而显著增大。遮阴显著增加了地枫皮和秀丽海桐的单位面积叶绿素含量,强光显著增加了块根紫金牛的单位面积类胡萝卜素含量、叶绿素a/b和类胡萝卜素/叶绿素比。地枫皮和块根紫金牛在50%遮阴强度下的总生物量最大,秀丽海桐总生物量随光强增大而显著增大。3种喀斯特植物幼苗对不同的光环境表现出较强的适应性,但强光不利于地枫皮和块根紫金牛幼苗的生长,而秀丽海桐幼苗对光的适应性很强。     

Study of different Trichoderma strains on growth characteristics and silymarin accumulation of milk thistle plant

Abstract

Biological control involves the use of beneficial organisms such as Trichoderma that promote positive responses by the plant. Trichoderma species produce and/or release a variety of compounds, including cell wall degrading enzymes and secondary metabolites, which enhance root development, crop productivity and resistance to biotic and abiotic stresses. This study examines the effects of the five Trichoderma strains (M7, KHB, G124-1, G46-3 and G46-7) on milk thistle including morphological characteristics and silymarin accumulation. This research indicated that treating milk thistle by M7 strain, significantly increased the highest branch length of plants, while strain KHB induced the production of silychristin, isosilybin and silymarin. Finally, strain G46-7 dramatically increased silydianin content in milk thistle plant. The findings suggested that certain Trichoderma strains are positive elicitors for promoting growth characteristics and silymarin accumulation in Silybum marianum (L.) Gaertn.     

Efficient transformation of Arabidopsis thaliana: comparison of the efficiencies with various organs,plant ecotypes and Agrobacterium strains

Summary The efficiency of Agrobacterium-mediated transformation of Arabidopsis thaliana was compared with different organs, Arabidopsis ecotypes, and Agrobacterium strains. Efficiency of shoot regeneration was examined using hypocotyl, cotyledon and root explants prepared from young seedlings. Hypocotyl expiants had the highest regeneration efficiency in all of the four Arabidopsis ecotypes tested, when based on a tissue culture system of callus-inducing medium (CIM: Valvekens et al. 1988) and shoot-inducing medium (SIM: Feldmann and Marks 1986). Histochemical analysis using the ß-glucuronidase (GUS) reporter gene showed that the gusA gene expression increased as the period of preincubation on CIM was extended, suggesting that dividing cells are susceptible to Agrobacterium infection. In order to obtain transgenic shoots, hypocotyl explants preincubated for 7 or 8 days on CIM were infected with Agrobacterium containing a binary vector which carries two drug-resistant genes as selection markers, and transferred to SIM for selection of transformed shoots. Of four Arabidopsis ecotypes and of three Agrobacterium strains examined, Wassilewskija ecotype and EHA101 strain showed the highest efficiency of regeneration of transformed shoots. By combining the most efficient factors of preincubation period, Arabidopsis ecotype, tissue, and bacterial strain, we obtained a transformation efficiency of about 80–90%. Southern analysis of 124 transgenic plants showed that 44% had one copy of inserted T-DNA while the others had more than one copy.Abbreviations AIM Agrobacterium infection medium - CIM callus-inducing medium - CTAB cetyltrimethylammonium bromide - 2,4-D 2,4-dichlorophenoxy-acetic acid - GUS ß-glucuronidase - hph hygromycin phosphotransferase - IAA indole-3-acetic acid - IBA indole-3-butyric acid - 2ip N -(2-isopentenyl) adenine - NPTII neomycin phosphotransferase II - RIM root-inducing medium - 35S cauliflower mosaic virus 35S promoter - SIM shoot-inducing medium     

Effects of environmental conditions and space on species turnover for three plant functional groups in Brazilian savannas

AimsDifferent plant functional groups display diverging responses to the same environmental gradients. Here, we assess the effects of environmental and spatial predictors on species turnover of three functional groups of Brazilian savannas (Cerrado) plants—trees, palms and lianas—across the transition zone between the Cerrado and Amazon biomes in central Brazil.     

A comparison of irradiance and phosphorus effects on the growth of three submerged macrophytes

A fully factorial pond experiment was designed using two irradiance levels and two phosphorus concentrations to investigate irradiance and phosphorus effects on the growth of three submerged macrophytes: common waterweed (Elodea canadensis), Eurasian water milfoil (Myriophyllum spicatum), and water stargrass (Zosterella dubia). Results revealed that higher irradiance (230 μmol s⁻¹ m⁻² vs. 113 μmol s⁻¹ m⁻² at 2 m depth) had significant positive effects on submerged macrophyte growth: increasing the number of individuals (seven-fold), the number of species surviving (two-fold), aboveground biomass (11-fold), belowground biomass (10-fold), and total biomass (11-fold), whereas elevated sediment phosphorus (2.1–3.3 mg g⁻¹ vs. 0.7 mg g⁻¹ dry sediment) did not have any significant impact. However, responses to irradiance differ among macrophyte species due to their morphology and physiology. Waterweed increased in numbers of individuals and total biomass under high irradiance while biomass per individual remained the same (∼0.02 g). The other species increased both in numbers and biomass per individual. These results suggest that increased irradiance rather than decreased phosphorus loading is the main driver of changes in submerged macrophytes in North American temperate lake ecosystems.     

A comparison of the prevalence of Spirocerca lupi in three groups of dogs with different life and hunting styles

The prevalence of Spirocerca lupi in 260 privately owned dogs with different life and hunting styles in Greece was based on the examination of randomly taken faecal samples using Teleman's sedimentation technique. The dogs did not demonstrate any clinical signs of spirocerciasis. Although the prevalence was 10%, it was found to be significantly higher in trace hunting dogs (21%), than in scent hunting dogs (5%) and household pets (0%). There was no relationship between prevalence and age/sex of dogs. The impact of life and hunting styles on the prevalence of S. lupi in the dog and that of the faecal examination technique, are discussed.     

Short-term effects of two aphid species on plant growth and root respiration of three leguminous species

The short-term effects of cowpea aphids ( Aphis craccivora Koch) and pea aphids ( Acyrthosiphon pisum Harris), both Homoptera: Aphididae, on plant growth and respiration of excised, intact roots of cowpea [ Vigna unguiculata (L.) Walp. cv. Caloona], broadbean ( Vicia faba L. cv. Aquadulce) and garden pea ( Pisum sativum L. cv. Victory Freezer) seedlings were investigated, but not all plant-aphid combinations were used. Plant and root mean relative growth rates were significantly reduced within 10 days in the infested plants. Rates of total root respiration were was also significantly reduced in all infested plants within 10 days, presumably because of the reduced availability of translocate to the roots. The contribution of the cytochrome pathway to root respiration was significantly greater in control than in infested plants. The activity and engagement of the alternative respiratory pathway was also greater in control plants, and was absent in infested plants after 10 days infestation in all cases but one. These data indicate that the roots of aphid-infested plants were more efficient, in terms of energy conversion, than their respective controls.     

施硒对三个香蕉品种植株生长、生理及果实品质的影响

该文以‘南天黄'' ‘中蕉9号'' ‘红香蕉''三个香蕉品种为材料,研究土壤淋施硒酸钠溶液对香蕉植株生长、果实产量和品质,以及叶片MDA、脯氨酸、硒含量的影响。结果表明:(1)每株0.25、0.50 g施硒处理能显著促进三个香蕉品种株高的增长,对‘南天黄'' ‘红香蕉''基茎围的增长促进作用显著,对‘中蕉9号''基茎围促进作用不显著。(2)施硒对植株营养生长过程中叶片MDA含量的影响较小,仅在部分时间段MDA含量显著升高或降低; 每株0.25、0.50 g的硒酸钠处理能显著降低三个香蕉品种叶片中脯氨酸含量。施硒对香蕉叶片中硒含量具有显著影响,施硒浓度越高,叶片中硒含量也越高。(3)施硒能显著提高各香蕉品种单株产量,对‘中蕉9号'' ‘红香蕉''单果重促进作用显著,对‘南天黄''单果重促进作用不显著; 每株0.25 g施硒处理,‘中蕉9号''的单株产量为24.38 kg、单果重为165.86 g,分别比对照高出了12.80%、14.69%。(4)土施适宜浓度的硒酸钠能提高香蕉果实中维生素C、钾含量,‘南天黄'' ‘中蕉9号'' ‘红香蕉''三个香蕉品种施硒后维生素C含量最高可达12.7、13.9、10.6 mg·100g^-1,比对照分别提高了12.72%、18.84%、29.39%; 钾含量最高可达349、279、397 mg·100g^-1,比对照分别提高29.62%、33.28%、47.77%。(5)硒处理浓度越高,果实中硒含量也越高; 对照处理的香蕉果实硒含量未达到富硒标准,每株经0.25、0.50 g硒酸钠处理后三个香蕉品种的果实硒含量均达到富硒标准。综上认为,土壤淋施硒酸钠溶液能提高香蕉果实中的硒含量,促进香蕉植株生长、提升果实品质,且对降低叶片中MDA和脯氨酸含量具有一定影响,但对不同香蕉品种的影响效果存在差异,该研究结果为富硒香蕉的生产栽培提供了理论依据。