Initiation of morphogenic cell-suspension and protoplast cultures of barley (Hordeum vulgare L.)

Cell-suspension cultures were initiated from embryogenic calli of various barley cultivars. Seven fast-growing suspension lines were obtained from four different cultivars (cvs. Dissa, Emir, Golden Promise and Igri). Two of these cell suspensions showed morphogenic capacity. From a cell suspension of cv. Dissa, albino plantlets were regenerated when aggregates were cultured on solid medium. Aggregates of cv. Igri usually stopped differentiation at the globular stage, but occasionally formed scutellum-like structures. Five suspension lines were used for protoplast isolation and culture. Dividing protoplasts were obtained from all lines, but with cv. Igri a few divisions only and no further development were observed. Protoplasts from the various lines differed in the time of first division (2–14 d), division frequency (0.09–70.9%) and efficiency of colony formation (0.09–7.3%). Protoplasts isolated from the morphogenic cell suspension of cv. Dissa developed compact calli which sporadically regenerated albino plantlets.Abbreviations CC, MS, N6, SH, Kao8p culture media; see Material and methods - cv chltivar - dicamba 3,6-dichloro-o-anisic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - picloram 4-amino-3,5,6-trichloropicolinic acid     

The histogenesis of somaclones from tomato (Lycopersicon esculentum Mill.) cotyledons

Summary A histological study ofin vitro cultured cotyledonary expiants of tomato (Lycopersicon esculentum) was performed in order to determine the site (differentiated tissue or developing callus) and the mode of plant regeneration.Results have shown that callus develops at the excision sites of cotyledonary expiants and that shoots are formed exclusively within the unorganized callus: excision areas are the only morphogenetic sites and the proximal excision is the preferred site for plant regeneration.Shoots differentiate by organogenesis within the superficial region of the callus. Few neocambial cells cooperate in the neoformation. Origin from a single cell is highly unlikely since rarely observed single activated cells never developed into shoots.Regenerated plants may be chimeras if invitro culture induces genetic diversity in the initial cells.Abbreviations IAA Indole-3-acetic acid - c callus - d vegetative dome - s shoot - ad adaxial - ab abaxial - t tracheid - p parenchyma - S sieve tube     

从“湖北光敏感核不育水稻”的未受精子房和花药培养出单倍体植株

采用10种诱导培养基,培养湖北光敏感核不育水稻农垦58品种的未受精子房和花药。共培养未受精子房2790个,获得胚囊愈伤组织17块,最高诱导频率达3.33%,其中2块分化出绿苗。培养花药16740个,获得花药愈伤组织15块,最高诱导频率为0.92%,其中3块分化出苗,2丛白苗,1株绿苗。胚囊植株和花粉植株经根尖染色体检查为单倍体,2n=x=12。实验证明,液体培养、2,4-D0.2-0.5 mg/1、低温预处理对诱导胚囊愈伤组织及花粉愈伤组织的形成具良好效果。     

Effect of transferrin on amphibian limb regeneration: a blastema cell culture study

Summary In order to study mitogenic control during axolotl limb regeneration, we have developed a primary blastema cell culture as a very sensitive bioassay for blastema mitogens. Transferrin, an iron-binding glycoprotein which has been shown to be the neurotrophic factor for muscle cells, is the mitogen which has been analysed in the present report. Addition of approximately 2 g human transferrin/ ml of serum-free culture medium enhances blastema cell proliferation 11-fold over control levels and 2-fold over that produced by the addition of nerve extracts or purified growth factors extracted from nerve tissues (basic and acidic fetal growth factor, FGF). At a higher concentration (20 g/ml), transferrin alone has no mitogenic effect unless the medium is also supplemented with FeCl₃ (100 M). The results are discussed with regard to the sensitivity of the blastema cell culture bioassay and in the context of the neurotrophic theory of urodele limb regeneration.     

Peptidergic neurons of the crab,Cardisoma carnifex,in defined culture maintain characteristic morphologies under a variety of conditions

Summary Peptidergic neurons dissociated from the neurosecretory cell group, the X-organ, of adult crabs (Cardisoma carnifex) show immediate outgrowth on unconditioned plastic dishes in defined medium. Most of the neurons can be categorized as small cells, branchers or veilers. A fourth type, superlarge, found occasionally, has a soma diameter greater than 40 m and multipolar outgrowth. We report here the effects on morphology that follow alterations of the standard defined culturing conditions. The three common types of neurons are present when cells are grown in crab saline or saline with l-glutamine and glucose (saline medium). Changes of pH between 7.0 to 7.9 have no effect. Osmolarity changes cause transient varicosities in small cells. In some veilers, pits rapidly appear in the veil and then disappear within 35 min. In cultures at 26° C instead of 22° C, veilers extend processes from the initial veil in a pattern similar to branchers, and the processes of adjacent veilers sometimes form appositions. Culturing in higher [K⁺]_o medium ([K⁺]_o=15–110 mM; standard=11 mM) has no long-term effect, but growth is arrested by [K⁺]_o greater than 30 mM. Cultures were also grown in media in which [Ca²⁺]_o ranged from 0.1 M to 26 mM (standard=13 mM). Outgrowth occured from all neuronal types in all [Ca²⁺]_o tested. Thus, the expression of different outgrowth morphologies occurs under a wide variety of culturing conditions.     

桑树叶肉原生质体培养再生植株

近年来,木本植物原生质作诱导再生植株的研究越来越受到国内外学者关注。但在林木树种中,迄今成功的种类仍然不多,在文     

Plant regeneration from haploid cell suspension-derived protoplasts of Mediterranean rice (Oryza sativa L. cv. Miara)

More than 750 plants were regenerated from protoplasts isolated from microspore callus-derived cell suspensions of the Mediterranean japonica rice Miara, using a nurse-feeder technique and N6-based culture medium. The mean plating efficiency and the mean regeneration ability of the protocalluses were 0.5% and 49% respectively. Flow cytometric evaluation of the DNA contents of 7 month old-cell and protoplast suspensions showed that they were still haploid. Contrastingly, the DNA contents of leaf cell nuclei of the regenerated protoclones ranged from 1C to 5C including 60% 2C plants. This was consistent with the morphological type and the fertility of the mature plants. These results and the absence of chimeric plants suggest that polyploidization occurred during the early phase of protoplast culture.Abbreviations BAP 6-benzylamino purine - 2,4-D 2,4-dichlorophenoxyacetic acid - FDA fluorescein diacetate - GA3 gibberellic acid - NAA -naphthaleneacetic acid - PAS periodic acid Schiff - PCM protoplast culture medium - PCV packed cell volume     

Effects of the stereochemical orientation of phenethylamines and imidazolines on alpha-adrenergic receptor-mediated DNA synthesis in primary cultured rat hepatocytes.

The hepatic alpha 1-adrenergic receptor mediates a variety of hepatic functions including respiration, glycogenolysis, gluconeogenesis, and growth. We have utilized a rat primary hepatocyte culture system to show that the alpha 1-adrenergic receptor can be activated in a stereoselective manner by a series of phenethylamines and catecholimidazolines resulting in the stimulation of DNA synthesis as determined by [3H]thymidine incorporation. The phenethylamines adhered to the Easson-Stedman hypothesis with a rank order of potency of (-)-(R)-norepinephrine (NE) greater than (+)-(S)-NE greater than the desoxy analog dopamine (DA) for the stimulation of DNA synthesis. However, the 2-substituted catecholimidazolines did not follow this trend and demonstrated an order of potency of the desoxy analog 3,4-dihydroxybenzyl imidazoline (DHT) greater than or equal to (-)-(R)-2-(3,4,alpha-trihydroxybenzyl)imidazoline (TBI) greater than (+)-(S)-TBI. 4-Substituted catecholimidazolines were less potent as inducers of DNA synthesis than the corresponding 2-substituted analogs with an order of potency of (+)-(R)-4-(3,4-dihydroxybenzyl)imidazoline (DBI) greater than (+,-)-(R,S)-DBI greater than (-)-(S)-DBI. When the beta-hydroxyl moiety of NE is replaced with an amino group as in 3,4-dihydroxyphenylethylenediamine, the isomers are less active than the beta-hydroxylated analogs and also demonstrate no stereoselectivity for the stimulation of DNA synthesis. These results demonstrate that the hepatic alpha 1-adrenergic receptor can recognize various isomeric forms of these compounds and that hepatocellular growth can be modulated in a stereoselective manner by phenethylamines and imidazolines.     

The gap theory in forest dynamics

Since the late 1970s, ecologists interested in forest dynamics have focused their attention to the responses of individuals, populations and communities to “gaps” which are openings created in the forest canopy. This review intended to introduce some collective knowledge on major subjects of the gap theory in forest dynamics, in relation to gap-disturbance regimes, tree regeneration behaviour and community structure.     

Growth and photosynthetic response of nine tropical species with long-term exposure to elevated carbon dioxide

Summary Seedlings of nine tropical species varying in growth and carbon metabolism were exposed to twice the current atmospheric level of CO₂ for a 3 month period on Barro Colorado Island, Panama. A doubling of the CO₂ concentration resulted in increases in photosynthesis and greater water use efficiency (WUE) for all species possessing C₃ metabolism, when compared to the ambient condition. No desensitization of photosynthesis to increased CO₂ was observed during the 3 month period. Significant increases in total plant dry weight were also noted for 4 out of the 5 C₃ species tested and in one CAM species, Aechmea magdalenae at high CO₂. In contrast, no significant increases in either photosynthesis or total plant dry weight were noted for the C₄ grass, Paspallum conjugatum. Increases in the apparent quantum efficiency (AQE) for all C₃ species suggest that elevated CO₂ may increase photosynthetic rate relative to ambient CO₂ over a wide range of light conditions. The response of CO₂ assimilation to internal C_i suggested a reduction in either the RuBP and/or Pi regeneration limitation with long term exposure to elevated CO₂. This experiment suggests that: (1) a global rise in CO₂ may have significant effects on photosynthesis and productivity in a wide variety of tropical species, and (2) increases in productivity and photosynthesis may be related to physiological adaptation(s) to increased CO₂.