Plant regeneration from cotyledon protoplasts of Brassica carinata

Protoplasts isolated from cotyledons of Brassica carinata, underwent sustained division when cultured at 5.0 × 10⁴ ml^-1 in modified 8p medium (KM8P) with 1.0% (w/v) Seaplaque agarose. Cell colonies produced callus when agarose droplets, in which the protoplasts were embedded, were transferred to K8 medium with 0.6% (w/v) Sigma Type I or Type VII agarose at day 16, giving a plating efficiency of 1.6%. Seventy percent of the protoplast derived-tissues produced shoot buds after subculture to MS medium containing 3.0% (w/v) sucrose, 1.125 mgl^-1 BAP, 0.035 mgl^-1 GA and 0.6% (w/v) Type I agarose, resulting in shoot formation from 1.1% of the protoplasts originally plated. Protoplast-derived colonies transferred to hormone-free MS medium with 1.0% (w/v) sucrose and 0.6% (w/v) Type I agarose produced roots. The latter gave rise to shoots after excision from the parent callus and culture on MS medium with 3.0% sucrose, 0.225 mgl^-1 BAP, and 0.6% (w/v) Type I agarose. Shoots regenerated directly from protoplast-derived calli, or indirectly from roots, developed prolific root systems when placed on hormone-free MS medium with 1.0% (w/v) sucrose and 0.6% (w/v) Type I agarose.Abbreviations BAP 6-benzylaminopurine - CH casein hydrolysate - 2,4-D 2,4-dichlorophenoxyacetic acid - GA gibberellic acid - K kinetin - NAA -naphthaleneacetic acid - MES 2(N-morpholino)ethanesulphonic acid, 2,iP-6(,-dimethylallyamino) purine - IAA indole-3-acetic acid - Z zeatin - ZR zeatin riboside     

Somatic embryogenesis from pea embryos and shoot apices

Conditions were defined for plant regeneration via somatic embryogenesis in pea, using explants from immature zygotic embryos or from shoot apices. For the induction of somatic embryos, an auxin (picloram or 2,4-dichlorophenoxyacetic acid) was required. Embryogenic callus originated from embryonic axis tissue of immature embryos and from the axillary-bud region and the plumula of shoot apices. A clear effect of embryo size on somatic embryogenesis was shown. There were differences in frequency of somatic embryogenesis among the five genotypes used in the study. Additions of BA to auxin-containing medium reduced embryo production. Histological examinations confirmed the embryogenic nature of the immature embryo cultures and revealed that somatic embryos originated from the meristematic areas near the callus surface.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - NAA naphthaleneacetic acid - picloram 4-amino-3,5,6-trichloropicolinic acid     

The effect of in vitro pretreatments on subsequent shoot organogenesis from excised Rubus and Malus leaves

Shoot regeneration from Rubus leaves was obtained on a medium containing MS salts, vitamins and sugars, Staba vitamins, casein hydrolysate (100 mg l^–1) and 10 M thidiazuron. Shoot regeneration from Malus leaves was obtained on N⁶ rice anther medium with 5 M thidiazuron. In vitro pretreatment of source shoots with either colchicine or thidiazuron enhanced the organogenic potential of detached leaves of two Rubus hybrids. The response to colchicine was quadratic and occurred at non-mutagenic concentrations (75–250 M). The response to thidiazuron was exponential between 0 and 5 M. When applied as a pretreatment, the effectiveness of several different cytokinins (benzyladenine, thidiazuron, zeatin) at enhancing Malus and Rubus organogenesis was related to the shoot proliferation activity of the cytokinin and to treatment-induced variation in leaf and petiole size.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - IBA indolebutyric acid - MS Murashige & Skoog basal medium devoid of plant growth regulators - OI organogenesis-initiating subculture - PTI colchicine pretreatment subculture - PTII cytokinin pretreatment subculture - NAA naphthaleneacetic acid - TDZ thidiazuron - zeatin trans-zeatin     

Induction of callus and plant regeneration in Vicoa indica

Callus cultures were initiated from the stem and leaf explants of aseptically grown Vicoa indica. A simple method is described for plant regeneration from callus and the rapid multiplication of the plants thus obtained. Callus initiation was optimum in Gamborg B5 (B5) basal medium containing either 2.0 mg l^-1 naphthaleneacetic acid (NAA) with 0.2 mg l^-1 kinetin (Kn) or 2.0 mg l^-1 6-benzylaminopurine (BAP) with 0.2 mg l^-1 NAA. The calli initiated on B5 medium were able to proliferate on both Murashige and Skoog (MS) and B5 basal medium. Shoot primordia were obtained from greenish callus on passage to B5 basal medium containing 3.0 mg l^-1 BAP and 1.0 mg l^-1 Kn. On further subculture onto B5 medium containing 0.2 mg l^-1 Kn the shoot primordia developed into plantlets.     

In vitro plantlet formation from juice vesicle callus of satsuma (Citrus unshiu Marc.)

Callus was induced from juice vesicles of satsuma mandarin on Murashige & Skoog medium supplemented with -naphthaleneacetic acid (NAA), kinetin (K) and gibberellin (GA). Adventitious embryoids arose from the callus tissue on the medium containing 1 mgl^–1 NAA alone. The embryoids grew into embryos which resulted in a plantlet on medium containing 1 mgl^–1 GA.Abbreviations GA gibberellin - K kinetin - NAA -naphthaleneacetic acid     

Prosaposin Facilitates Sciatic Nerve Regeneration In Vivo

Abstract: Prosaposin, a multifunctional protein, is the precursor of saposins, which activate sphingolipid hydrolases. In addition to acting as a precursor for saposins, prosaposin has been shown to rescue hippocampal CA1 neurons from lethal ischemic damage in vivo and to promote neurite extension of neuroblastoma cells in vitro. Here we show that prosaposin, when added to a collagen-filled nerve guide after sciatic nerve transection in guinea pigs, increased dramatically the number of regenerating nerve fibers within the guide. To identify the target neurons of prosaposin during peripheral nerve regeneration, we determined the degree of atrophy and chromatolysis of neurons in the spinal anterior horn and dorsal root ganglia on the prosaposin-treated and untreated side. The effect of prosaposin on large spinal neurons and small neurons of the dorsal root ganglion was more conspicuous. Subsequent immunohistochemistry demonstrated that the atrophy of cholinergic large neurons in the anterior horn is prevented to significant extent by prosaposin treatment. These findings suggest that prosaposin promotes peripheral nerve regeneration by acting on α-motor neurons in the anterior horn and on small sensory neurons in the dorsal root ganglion. The present study raises the possibility of using prosaposin as a tool for the treatment of peripheral nerve injuries.     

Effect of distance,aggregation, and habitat on levels of seed predation for two mammal — dispersed neotropical rain forest tree species

The effect of seed aggregation and distance from conspecific trees on seed predation was experimentally examined for two neotropical tree species, Macoubea guianensis (Apocynaceae) and Pouteria sp. (Sapotaceae) in a lowland tropical rain forest in northeastern Peru. Results of these experiments are discussed in the context of the Janzen-Connell model (Janzen 1970; Connell 1971), which predicts decreased seed survival near parent trees due to either density-or distance-responsive mortality, and Howe's model (Howe 1989) which predicts that trees with seeds dispersed in clumps (aggregated) will not suffer density-dependent predation, and will have higher survival of seeds near the parent tree than other trees. We also examined whether predation on seeds of these species was affected by seed placement in or near 30-m-wide strips regenerating after clear-cutting. Both species appeared to be mammal-dispersed but differed in how frugivores handled seeds, seed size, overall fruit crop size, and gemination time. Neither of the two species studied appeared to suffer seed predation in a manner predicted by the Janzen-Connell model, and patterns of seed predation for only one of the species was similar to predictions of Howe's model. For neither species did seed predation along the edge of, or in the center of, regenerating clear cuts differ from predation 15 m into the primary forest. For Pouteria, seed predation in and near regnerating strips was significantly greater than around forest trees, but the opposite pattern held for Macoubea. Overall, seed predation was much greater on Macoubea. The difference in seed predation for these two species was most likely a result of differences in the types of seed predators that attacked these two species.     

Plant regeneration in Kentucky bluegrass (Poa pratensis L.) via coleoptile tissue cultures

Summary Plant regeneration in Kentucky bluegrass (Poa pratensis L. cv. Touchdown) via culture of seedling tissues was investigated. When coleoptile, leaf, and stem sections of dark-germinated seedlings were cultured on Murashige and Skoog (MS) medium, different types of callus were produced, depending on the expiant source and growth regulator combinations. Only compact-friable callus (type 3) and moderately compact, friable callus (type 2) produced shoots upon subculture. The nonstructured watery callus (type 4) produced roots without shoots. Shoot differentiation from callus tissues was highest when the culture medium contained 0.2 mgL^–1 picloram + 0.01 mgL^–1 -naphthaleneacetic acid (NAA). Calli grown from coleoptiles had higher shoot regeneration frequency (32%) than that obtained from either stem sections (12%) or young leaf tissues (2%) of the same seedlings. Some organogenic callus lines produced exclusively green plants, while others produced albino shoots or a mixture of green and albino shoots. The green plants were multiplied in a medium containing 0.1 mgL^–1 BAP plus either 0.2 mgL^–1 picloram or 0.1 mgL^–1 indole-3-acetic acid (IAA). Over 90% of the cultures in the shoot proliferation medium produced roots in 4 weeks. The rooted plants were successfully established in soil medium and grown in the greenhouse.Abbreviations BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - MS Murashige and Skoog (1962) medium - NAA -naphthaleneacetic acid - picloram 4-amino-3,5,6-trichloropicolinic acid - TDZ thidiazuron     

肝再生的调控及原癌基因表达

肝脏再生过程中受到多种体液因素的调控。肝细胞生长因子（ＨＧＦ）、肝刺激因子（ＨＳＳ）等对肝细胞有促分裂作用;转化生长因子β１（ＴＧＦβ１）等则具有抑制作用。此外,肝再生还需要去甲肾上腺素（ＮＥ）、胰岛素等辅助分裂原的存在,共同调节肝再生。肝细胞分裂增殖与原癌基因表达密切相关。肝细胞从静息期进入细胞周期,以及在整个细胞周期中,某些原癌基因有特征性的表达。     

Prolific shoot regeneration from immature embryo explants of sainfoin (Onobrychis viciifolia Scop.)

Summary Immature cotyledons and embryo axes of sainfoin were cultured on Murashige and Skoog (MS) media supplemented with various concentrations of 6-benzylaminopurine (BAP) and a-naphthaleneacetic acid (NAA) to induce adventitious shoot regeneration. The highest frequency of shoot regeneration occurred following an initial callus growth on a MS medium containing 0.5 mg/l BAP and 2 mg/l NAA. Immature embryo axes showed higher regeneration capacity than immature cotyledons, however, shoot elongation was best achieved on immature cotyledons. Regenerated shoots were excised and rooted in half strength MS medium with 1 mg/l indole-butyric acid (IBA) or 1 mg/l NAA. The rooted plantlets were finally transferred to compost.