石刁柏花粉植株诱导及其起源鉴定的研究

采用高渗蔗糖溶液预处理石刁柏花药可以显著抑制花药体细胞分裂和提高花粉愈伤组织诱导率。愈伤组织在转入含低浓度激素的培养基中分化得到了花粉植株。其中单倍体、二倍体、四倍体和非整洁体分别占４．３％、６４．５％、１７．２％和１４．０％。单倍体的频率随愈伤组织培养时间延长而下降,石刁柏幼茎中莽草酸脱氢酶同工酶的多态性表现稳定,用其作为遗传标记结合细胞学方法可以鉴定花粉植株的起源。     

Functional molecular aspects of the NADH dehydrogenases of plant mitochondria

There are multiple routes of NAD(P)H oxidation associated with the inner membrane of plant mitochondria. These are the phosphorylating NADH dehydrogenase, otherwise known as Complex I, and at least four other nonphosphorylating NAD(P)H dehydrogenases. Complex I has been isolated from beetroot, broad bean, and potato mitochondria. It has at least 32 polypeptides associated with it, contains FMN as its prosthetic group, and the purified enzyme is sensitive to inhibition by rotenone. In terms of subunit complexity it appears similar to the mammalian and fungal enzymes. Some polypeptides display antigenic similarity to subunits fromNeurospora crassa but little cross-reactivity to antisera raised against some beef heart complex I subunits. Plant complex I contains eight mitochondrial encoded subunits with the remainder being nuclear-encoded. Two of these mitochondrial-encoded subunits, nad7 and nad9, show homology to corresponding nuclear-encoded subunits inNeurospora crassa (49 and 30 kDa, respectively) and beef heart CI (49 and 31 kDa, respectively), suggesting a marked difference between the assembly of CI from plants and the fungal and mammalian enzymes. As well as complex I, plant mitochondria contain several type-II NAD(P)H dehydrogenases which mediate rotenone-insensitive oxidation of cytosolic and matrix NADH. We have isolated three of these dehydrogenases from beetroot mitochondria which are similar to enzymes isolated from potato mitochondria. Two of these enzymes are single polypeptides (32 and 55 kDa) and appear similar to those found in maize mitochondria, which have been localized to the outside of the inner membrane. The third enzyme appears to be a dimer comprised of two identical 43-kDa subunits. It is this enzyme that we believe contributes to rotenone-insensitive oxidation of matrix NADH. In addition to this type-II dehydrogenases, several observations suggest the presence of a smaller form of CI present in plant mitochondria which is insensitive to rotenone inhibition. We propose that this represents the peripheral arm of CI in plant mitochondria and may participate in nonphosphorylating matrix NADH oxidation.     

光合细菌H3菌株色素分析

H3菌株系由盐田微生物层中分离获得的光合细菌株。具有丰富的天然色素。经活细胞色素光谱吸收峰值测定,色素经有机溶剂提取、硅胶薄板层析、SDS－PAGE电泳等,结果表明H3菌株的主要色素包括细菌叶绿素a、细菌脱镁叶绿素（Bacteriophaeophytin）和三种类胡萝卜素。总胡萝卜素含量占细胞于重的0．6％,胡萝卜素蛋白复合体的分子量约11,000.培养条件的差异对色素形成及相对含量有不同程度的影响。     

Comparative Physiology and Behaviour of the Mycoparasites Pythium acanthophoron, P. oligandrum and P. mycoparasiticum

Pythium acanthophoron (two isolates) was as aggressive as P. oligandrum in hyphal interactions with Fusarium oxysporum on water agar films. It caused rapid post-contact lysis or cytoplasmic coagulation of the host, and often branched and penetrated the host at contact points. P. acanthophoron grew across a range of fungi on pre-colonized agar plates; the range was narrower than for P. oligandrum but broader than for P. mycoparasiticum. In chemically defined liquid media, P. acanthophoron was unique among the six known mycoparasitic Pythium spp. in requiring organic nitrogen but not thiamine. It also grew on mannitol as the sole carbon source in the presence of calcium or sterols or both. However, individual isolates of the three mycoparasitic species showed different responses to calcium and the sterols ergosterol, cholesterol and beta-sitosterol when grown on mannitol. All three mycoparasites required components of molasses, carrot extract or sunflower seed extract to produce oogonia in culture; they formed few oogonia on potato extract, with or without dextrose, even when supplied with sterols. The three mycoparasites were less tolerant of high NaCl levels in culture than were three phytopathogens (P. aphanidermatum, P. ultimum, P. graminicola), in contrast to a previous report for P. oligandrum and P. ultimum. These in vitro studies suggest that P. acanthophoron has potential for use as a biocontrol agent instead of, or in addition to, P. oligandrum.     

光质对石刁柏愈伤组织培养中生长和过氧化物酶的影响

报道了在石刁柏愈伤组织培养中,采用５种不同光质处理,对愈伤组织生长及其过氧化物酶（ＰＯＤ）活性及同工酶的影响,实验表明,不同光质处理对生长有不同的效应,蓝光、红光下的培养物生长较快。不同光质对培养物质的ＰＯＤ活性亦有不同效应,ＰＯＤ同工酶谱亦有不同,蓝光、红光下的培养物,ＰＯＤ活性较高。ＰＯＤ活性变化与愈伤组织生长呈正相关。     

Relationship of alpha MSH-specific neurons to the arcuate opiocortin neuronal system as determined by dual antigen immunocytochemical procedures

The cross-immunoreactivity, topography, and fiber projections of the alpha MSH-immunoreactive specific neurons in the forebrain of the rat appear to be distinctly different from that of the neurons in the hypothalamic arcuate opiocortin system. The cell bodies, immunoreactive only to -MSH, have a specific pattern of distribution in the dorsal and lateral hypothalamic regions from the level of the retrochiasmatic region to the premammillary area of the posterior hypothalamus. Immunoreactive fibers of these cells appear to extend into regions of the cerebral cortex and hippocampus. An antomical relationship between the immunostained fibers and/or terminals of the arcuate opiocortin pool of neurons and the -MSH-immunoreactive perikarya is described utilizing the ABC (Avidin-Biotin-Peroxidase Complex) and ABC-GO (Glucose Oxidase) or glucose oxidase-antiglucose oxidase complex methods of immunocytochemistry in which two tissue antigens with contrasting colors are demonstrated in the same tissue section.     

Age-specific survivorship analysis ofHeliothis spp. Populations on cotton

Population dynamics of Heliothis virescens (F.) and Heliothis zea (Boddie ) (Lepidoptera: Noctuidae) eggs and larvae were studied for two years in a small plot of cotton, Gossypium hirsutum (L.). Due to morphological and ecological similarities, the pooled Heliothis population was considered for most of the analyses. Two generations of Heliothis eggs and larvae were completed during each year. Stage recruitment was estimated for the eggs and larval instars 2–6, and recruitment variances were estimated by a Monte Carlo method. A modified form of the Weibull distribution was developed and used as a model to characterize survivorship curves for each of the four Heliothis generations. A Type I survivorship curve (mortality rate increasing with age) was inferred for both Generation 1 (early season) data sets, whereas a Type II survivorship curve (mortality rate constant and thus independent of age) was inferred for both Generation 2 (late season) data sets. The shapes of the survivorship curves for the individual H. virescens and H. zea populations were inferred to be the same as those for the pooled populations. Analysis of the contributions of various factors to Heliothis stage-specific mortality indicated that natural enemies (predators and parasites) and the availability of food for larvae were responsible for between-generation differences in survivorship patterns.     

药用野生稻GBSS基因的系统发育及组织特异性表达

淀粉作为主要的碳水化合物在储藏能量方面发挥至关重要的作用。颗粒结合型淀粉合酶(GBSS)与直链淀粉的合成息息相关。尽管该酶的编码基因已在许多栽培植物中被分离和确定, 但有关它们在作物野生近缘种中的序列分歧和表达的研究却相对较少。该研究以药用野生稻(Oryza officinalis)为研究对象, 定性和定量地分析了GBSS编码基因的序列特点、与其它植物同源基因的进化关系以及在叶和种子中的表达情况。系统发育分析表明, 该酶在禾本科植物中分别由GBSSI和GBSSII基因编码。在药用野生稻中, 这2种基因所编码蛋白的氨基酸序列一致性为62%, 并且它们在不同器官内呈现时空分化表达, 其中GBSSI在种子中超强表达, GBSSII则主要在叶片表达。     

On the evolution of the bacterial major sigma factors

Summary The existence of internal sequence homologies between the N-terminal halves of the gram-negative bacterial major sigma factors and their C-terminal halves, which correspond to minor factors, is reported. In the case of Escherichia-Salmonella sigma-70, an apparent homology was even found between the C-terminal helix-turn-helix DNA-binding motif and the corresponding region of the peptide N half, which, however, is not directly engaged in promoter recognition. It is proposed that major sigma factors may have originated by duplication and fusion of a DNA unit related to the ancestral gene for the whole sigma family. Coevolution of major sigma structures and complex promoters is suggested.     

石刁柏体细胞胚胎发生过程中蛋白质及同工酶变化的研究

本文报道石刁柏胚性愈伤组织的可溶性蛋白质含量与组分、过氧化物酶和酯酶的活力及同工酶带均比其体细胞胚的要少。而在体细胞胚胎发生过程中,过氧化物酶和酯酶活力、可溶性蛋白质含量均以球形胚为最低,子叶分化期胚为最高而呈递增趋势;可溶性蛋白质组分以子叶分化期胚、成熟胚为最多,球形胚、香蕉形胚为最少;过氧化物酶同工酶带以梨形胚为最多,子叶分化期胚、成熟胚为最少;酯酶同工酶则以子叶分化期胚为最多,成熟胚为最少。胚性愈伤组织与体细胞胚均有其特异性可溶性蛋白质及同工酶带,可作为体细胞胚胎发生的分子标记。